JP2004058660A - Thermoreversible recording medium, thermoreversible recording label, thermoreversible recording member, image processing apparatus and image processing method - Google Patents

Abstract

[PROBLEMS] To sufficiently erase an image even when heating is performed using a thermal head for a very short time in the order of milliseconds, and to achieve sufficient erasability without changing erasing energy after image formation. Provided is a thermoreversible recording medium or the like which can maintain an image even when left at a high temperature for a long period of time to form an image having excellent storability, contrast, and visibility.
A heat-sensitive layer containing a resin and an organic low-molecular-weight compound and having a transparency that reversibly changes depending on the temperature is provided. (1) The heat-sensitive layer has a glass transition temperature change of -10 to 5 ° C. And a transparency temperature range of 30 ° C. or more, (2) the resin contains an acrylic polyol resin, and the glass transition temperature change in the heat-sensitive layer is −10 to 5 ° C., (3) the resin contains an acrylic resin, And (4) a thermoreversible recording medium in which the resin contains an acrylic polyol resin and the transparentization temperature range in the heat-sensitive layer is 30 ° C. or more.
[Selection diagram] Fig. 1

Description

【化２】

前記構造式（４−１）及び（４−２）中、ｍ及びｎは、０〜３０が好ましい。
【００９９】
Ｒ^８−Ｘ−Ｒ^９　　　　　　　　　　　　　　　　構造式（５）
前記構造式（５）中、Ｘは、シュウ酸ジアミド結合又はジアシルヒドラジド結合を表す。Ｒ^８及びＲ^９は、ＣＨ_３（ＣＨ_２）_ｍ−、又はＣＨ_３（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。ｍ及びｎは、０〜３０の整数を表す。
【０１００】
【化３】

前記構造式（６）中、Ｘ及びＹは、ウレタン結合、スルホニル結合、尿素結合、アミド結合、シュウ酸ジアミド結合、及びジアシルヒドラジド結合から選択される少なくともいずれかを表す。Ｒ^１０及びＲ^１２は、−（ＣＨ_２）_ｍ−、又は−（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。Ｒ^１１は、ＣＨ_３（ＣＨ_２）_ｍ−、又はＣＨ_３（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。ｍ及びｎは、０〜３０の整数を表す。Ａは、フェニル基、シクロヘキシル基、又は下記構造式（６−１）〜（６−２）のいずれかの基を表す。
【化４】

前記構造式（７）中、Ｘは、ウレタン結合、スルホニル結合、尿素結合、アミド結合、シュウ酸ジアミド結合、又はジアシルヒドラジド結合を表す。Ｒ^１０及びＲ^１２は、−（ＣＨ_２）_ｍ−、又は−（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。ｍ及びｎは、０〜３０の整数を表す。Ａは、フェニル基、シクロヘキシル基、又は下記構造式（６−１）〜（６−２）のいずれかの基を表す。
【０１０１】
【化５】

【０１０２】
【化６】

前記構造式（６−２）中、ｌは、１〜３の整数を表す。Ｚは、Ｒ^１３ＯＣＯ−、Ｒ^１３Ｏ−、又はＲ^１３−を表す。Ｒ^１３は、ＣＨ_３（ＣＨ_２）_ｍ−、又はＣＨ_３（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。ｍ及びｎは、０〜３０の整数を表す。
【０１０３】
【化７】

【０１０４】
【化８】

【０１０５】
前記構造式（８）及び（９）中、Ｘは、ウレタン結合、スルホニル結合、尿素結合、アミド結合、シュウ酸ジアミド結合及びジアシルヒドラジド結合から選ばれるいずれかを表す。Ｒ^１４は、−（ＣＨ_２）_ｍ−、又は−（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。Ｒ^１５は、ＣＨ_３（ＣＨ_２）_ｍ−、又はＣＨ_３（ＣＨ_２）_ｍ−Ｏ−（ＣＨ_２）_ｎ−を表す。ｍ及びｎは、０〜３０の整数を表す。
【０１０６】
前記直鎖炭化水素含有化合物の好ましい具体例としては、下記構造式（１０）〜（２６）のいずれかで表されるものが挙げられる。
Ｒ^１６−ＯＯＣＮＨ−Ｒ^１７−ＮＨＣＯＯ−Ｒ^１８　　　　構造式（１０）
Ｒ^１６−ＮＨＣＯＯ−Ｒ^１７−ＯＯＣＮＨ−Ｒ^１８　　　　構造式（１１）
Ｒ^１６−ＳＯ_２−Ｒ^１７−ＳＯ_２−Ｒ^１８　　　　　　　　構造式（１２）
Ｒ^１６−ＮＨＣＯＣＯＮＨ−Ｒ^１８　　　　　　　　　　　構造式（１３）
Ｒ^１６−ＣＯＮＨＮＨＣＯ−Ｒ^１８　　　　　　　　　　　構造式（１４）
Ｒ^１６−ＮＨＣＯ−Ｒ^１７−ＮＨＣＯＮＨ−Ｒ^１８　　　　構造式（１５）
Ｒ^１６−ＣＯＮＨ−Ｒ^１７−ＮＨＣＯＮＨ−Ｒ^１８　　　　構造式（１６）
Ｒ^１６−ＮＨＣＯＯ−Ｒ^１７−ＮＨＣＯＮＨ−Ｒ^１８　　　構造式（１７）
Ｒ^１６−ＮＨＣＯＮＨ−Ｒ^１７−ＮＨＣＯＮＨ−Ｒ^１８　　構造式（１８）
Ｒ^１６―ＮＨＣＯＯ−Ｒ^１７−ＯＯＣＮＨ−Ｒ^１８　　　　構造式（１９）
ただし、前記構造式（１０）〜（１９）中、Ｒ^１６及びＲ^１８は、アルキル基を表す。Ｒ^１７は、メチレン基、下記構造式（１０−１）又は下記構造式（１０−２）で表される基を表す。
【０１０７】
【化９】

【化１０】

ただし、前記構造式（１０−１）〜（１０−２）中、ｍ及びｎは、０〜２０の整数を表す。
【０１０８】
【化１１】

【０１０９】
【化１２】

【０１１０】
【化１３】

【０１１１】
【化１４】

【０１１２】
【化１５】

【０１１３】
【化１６】

【０１１４】
【化１７】

【０１１５】
前記構造式（１０）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１１ＯＯＣＮＨ（ＣＨ_２）_６ＮＨＣＯＯ（ＣＨ_２）_１１ＣＨ_３　　　　　　　　　融点：１１３℃
ＣＨ_３（ＣＨ_２）_１７ＯＯＣＮＨ（ＣＨ_２）_６ＮＨＣＯＯ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　融点：１１９℃
ＣＨ_３（ＣＨ_２）_２１ＯＯＣＮＨ（ＣＨ_２）_６ＮＨＣＯＯ（ＣＨ_２）_２１ＣＨ_３　　　　　　　　　融点：１２１℃
【化１８】

【０１１６】
前記構造式（１１）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯＯ（ＣＨ_２）_２ＯＯＣＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　　融点：１１５℃
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯＯ（ＣＨ_２）_４ＯＯＣＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　　融点：１１９℃
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯＯ（ＣＨ_２）_６ＯＯＣＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　　融点：１１１℃
【化１９】

【０１１７】
前記構造式（１２）で表される化合物の好ましい具体例としては、以下のものが挙げられる。

【０１１８】
前記構造式（１３）で表される化合物の好ましい具体例としては、以下のものが挙げられる。

【０１１９】
前記構造式（１４）で表される化合物の好ましい具体例としては、以下のものが挙げられる。

【０１２０】
前記構造式（１５）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯ（ＣＨ_２）_４ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　　融点：１４４℃
ＣＨ_３Ｏ（ＣＨ_２）_３ＮＨＣＯ（ＣＨ_２）_１１ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　融点：１４０℃
ＣＨ_３ＣＨ_２Ｏ（ＣＨ_２）_３ＮＨＣＯ（ＣＨ_２）_１１ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　融点：１３５℃
【０１２１】
前記構造式（１６）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１６ＣＯＮＨ（ＣＨ_２）_６ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　　融点：１４９℃
【０１２２】
前記構造式（１７）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯＯ（ＣＨ_２）_２ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　融点：１２７℃
【０１２３】
前記構造式（１８）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
ＣＨ_３（ＣＨ_２）_１７ＮＨＣＯＮＨ（ＣＨ_２）_６ＮＨＣＯＮＨ（ＣＨ_２）_１７ＣＨ_３　　　　　　　　　融点：１７７℃
【０１２４】
前記構造式（１９）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２０】

【０１２５】
前記構造式（２０）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２１】

【化２２】

【０１２６】
前記構造式（２２）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２３】

【０１２７】
前記構造式（２３）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２４】

【０１２８】
前記構造式（２４）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２５】

【０１２９】
前記構造式（２５）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２６】

【０１３０】
前記構造式（２６）で表される化合物の好ましい具体例としては、以下のものが挙げられる。
【化２７】

【０１３１】
前記直鎖炭化水素含有化合物と前記低融点の有機低分子化合物との混合質量比（低融点の有機低分子化合物：直鎖炭化水素含有化合物）としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、９５：５〜５：９５が好ましく、９０：１０〜１０：９０がより好ましく、８０：２０〜２０：８０が特に好ましい。前記混合質量比が前記数値範囲内にないと、前記低融点の有機低分子化合物が多すぎるときに、透明化温度幅が狭くなり、消去性が十分でないことがあり、前記直鎖炭化水素含有化合物が多すぎるときに画像を形成することができないことがある。
【０１３２】
前記低融点の有機低分子化合物又は前記高融点の有機低分子化合物以外に、他の有機低分子化合物を併用する場合、該他の有機低分子化合物としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、高級脂肪酸、高級脂肪酸のエステル、高級脂肪酸のエーテル、などが挙げられる。
前記高級脂肪酸としては、例えば、ラウリン酸、ドデカン酸、ミリスチン酸、ペンタデカン酸、パルミチン酸、ステアリン酸、ベヘン酸、ノナデカン酸、アラギン酸、オレイン酸、などが挙げられる。前記高級脂肪酸のエステルとしては、例えば、ステアリン酸メチル、ステアリン酸テトラデシル、ステアリン酸オクタデシル、ラウリン酸オクタデシル、パルミチン酸テトラデシル、ベヘン酸ドデシル、などが挙げられる。前記高級脂肪酸のエーテルとしては、例えば、Ｃ_１６Ｈ_３３−Ｏ−Ｃ_１６Ｈ_３３、などが挙げられる。前記高級脂肪酸のチオエーテルとしては、例えば、Ｃ_１６Ｈ_３３−Ｓ−Ｃ_１６Ｈ_３３、Ｃ_１８Ｈ_３７−Ｓ−Ｃ_１８Ｈ_３７、Ｃ_１２Ｈ_２５−Ｓ−Ｃ_１２Ｈ_２５、Ｃ_１９Ｈ_３９−Ｓ−Ｃ_１９Ｈ_３９、Ｃ_１２Ｈ_２５−Ｓ−Ｓ−Ｃ_１２Ｈ_２５、などが挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。これらの中でも、高級脂肪酸、特にパルミチン酸、ペンタデカン酸、ノナデカン酸、アラキン酸、ステアリン酸、ベヘン酸、リグノセリン酸等の炭素数１６以上の高級脂肪酸が好ましく、炭素数１６〜２４の高級脂肪酸が更に好ましい。
【０１３３】
前記感熱層におけるその他の成分としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、画像の形成を容易にする観点からは、界面活性剤、可塑剤、などが挙げられる
前記界面活性剤としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、陰イオン界面活性剤、陽イオン界面活性剤、非イオン界面活性剤、両性界面活性剤、などが挙げられる。
前記可塑剤としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、リン酸エステル、脂肪酸エステル、フタル酸エステル、二塩基酸エステル、グリコール、ポリエステル系可塑剤、エポキシ系可塑剤、などが挙げられる。
【０１３４】
前記感熱層の厚みとしては、特に制限はなく、目的に応じて適宜選択することができ、例えば、１〜３０μｍが好ましく、２〜２０μｍがより好ましい。
前記感熱層の厚みが、薄すぎると、白濁度が低下しコントラストが低くなることがあり、厚すぎると、層内での熱の分布が発生し均一に透明化することが困難となることがある。なお、前記有機低分子化合物の前記感熱層中の含有量を増加させると、白濁度を増加させることができる。
【０１３５】
本発明の熱可逆記録媒体は、前記感熱層のほかに、更に必要に応じて適宜選択した、支持体、着色層、空気層、光反射層、接着層、中間層、保護層、接着剤層、粘着層等のその他の層を有していてもよい。これら各層は、単層構造であってもよいし、積層構造であってもよい。
【０１３６】
前記熱可逆記録媒体の層構成としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、実開平２−３８７６号公報に記載されているように、支持体上に、感熱層と磁性材料を主成分とする磁気感熱層を有すると共に、少なくとも感熱層直下又は支持体の感熱層対応部分が着色されている層構成、特開平３−１３０１８８号公報に記載されているように、支持体上に、磁気感熱層、該磁気感熱層の上に光反射層、該光反射層の上に感熱層が設けられているような層構成、等が挙げられる、なお、前記磁気感熱層は、支持体の裏面、又は支持体と感熱層との間に設けることが好ましい。
【０１３７】
前記支持体としては、その形状、構造、大きさ等については、特に制限はなく、目的に応じて適宜選択することができ、前記形状としては、例えば平板状などが挙げられ、前記構造としては、単層構造であってもいし、積層構造であってもよく、前記大きさとしては、前記熱可逆記録媒体の大きさ等に応じて適宜選択することができる。
前記支持体の材料としては、例えば、無機材料、有機材料、などが挙げられる。前記無機材料としては、例えば、ガラス、石英、シリコン、酸化シリコン、酸化アルミニウム、ＳｉＯ_２、金属等が挙げられる。前記有機材料としては、例えば、紙、ポリエチレンテレフタレート、ポリカーボネート、ポリスチレン、ポリメチルメタクリレート等が挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。
前記支持体の厚みとしては、特に制限はなく、目的に応じて適宜選択するこができ、１００〜２，０００μｍが好ましく、１００〜１，０００μｍがより好ましい。
【０１３８】
前記熱可逆記録媒体には、前記感熱層を保護する目的で保護層を設けることができる。前記保護層の材料としては、シリコーンゴム、シリコーン樹脂（例えば、特開昭６３−２２１０８７号公報）、ポリシロキサングラフトポリマー（例えば、特開昭６３−３１７３８５号公報）、紫外線硬化樹脂又は電子線硬化樹脂（例えば、特開平２−５６６号公報）、などが挙げられる。
これらの材料を塗布する際には、通常、溶剤が用いられる。前記溶剤としては、前記感熱層における前記樹脂及び前記有機低分子化合物を溶解し難いものが好ましく、例えば、ｎ−ヘキサン、メチルアルコール、エチルアルコール、イソプロピルアルコール等のアルコール系溶剤、などが挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよく、コスト面でアルコール系溶剤が好ましい。
【０１３９】
前記保護層は、前記感熱層のアクリル樹脂を硬化するのと同時に硬化させることができる。この場合、前記支持体上に前記感熱層を形成した後、前記保護層を塗布、乾燥する。その後、熱、紫外線、電子線照射等を行い、それぞれの層を硬化させる。
前記保護層の厚みとしては、特に制限はなく、目的に応じて適宜選択することができ、例えば、０．１〜１０．０μｍが好ましい。前記保護層の厚みが０．１μｍ未満であると、前記感熱層の保護効果が十分でないことがあり、１０．０μｍを超えると、熱感度が低下することがある。
【０１４０】
前記熱可逆記録媒体には、保護層形成液の溶剤やモノマー成分等から感熱層を保護する目的で、前記保護層と前記感熱層との間に中間層を設けることができる（例えば、特開平１−１３３７８１号公報参照）。前記中間層の材料としては、感熱層中の樹脂の材料として挙げたもの以外に、熱可塑性樹脂、熱硬化性樹脂等の樹脂成分を用いることができる。該樹脂成分としては、例えば、ポリエチレン、ポリプロピレン、ポリスチレン、ポリビニルアルコール、ポリビニルブチラール、ポリウレタン、飽和ポリエステル、不飽和ポリエステル、エポキシ樹脂、フェノール樹脂、ポリカーボネート、ポリアミド、などが挙げられる。
前記中間層の厚みとしては、特に制限はなく、目的に応じて適宜選択するこができ、０．５〜１０μｍが好ましい。
【０１４１】
前記熱可逆記録媒体には、前記支持体と前記感熱層との間に視認性を向上させる目的で、着色層を設けることが好ましい。前記着色層は、着色剤及び樹脂バインダーを含有する溶液、又は分散液を対象面に塗布し、乾燥するか、あるいは、単に着色シートを貼り合せることにより形成することができる。
前記着色剤としては、上層である前記感熱層の透明及び白濁の変化を反射画像として認識できるものであれば特に制限はなく、例えば、赤、黄、青、紺、紫、黒、茶、灰、橙、緑等の色を有する染料、顔料等が使用される。なお、前記樹脂バインダーとしては、各種熱可塑性樹脂、熱硬化性樹脂、紫外線硬化性樹脂などが使用される。
【０１４２】
前記熱可逆記録媒体には、カラー印刷層を設けることができる、前記カラー印刷層における着色剤としては、従来のフルカラー印刷に使用されるカラーインク中に含まれる各種の染料及び顔料等が挙げられ、前記樹脂バインダーとしては各種の熱可塑性、熱硬化性、紫外線硬化性又は電子線硬化性樹脂、等が挙げられる。該カラー印刷層の厚みとしては、印刷色濃度に対して適宜変更されるため、所望の印刷色濃度に合わせて選択することができる。
【０１４３】
前記熱可逆記録媒体は、前記支持体と前記感熱層との間に、空気層による非密着部を有していてもよい。前記感熱層に用いられる前記有機高分子化合物の屈折率が１．４〜１．６程度であり、空気の屈折率１．０との差が大きいため、該空気層を有すると、前記感熱層と前記非密着部との界面で光が反射し、該感熱層が白濁状態の時に白濁度を増幅することができ、視認性を向上させることができ、該空気層による非密着部を表示部として好適に用いることができる。
前記空気層は、断熱層としても機能するため、感熱度を向上させることができ、また、クッション層としても機能し、サーマルヘッドからの圧力を分散させることができ、前記感熱層の変形、粒子状の前記有機低分子化合物の拡散等を防ぎ、繰返し耐久性を向上させることができる。
【０１４４】
また、前記熱可逆記録媒体には、ヘッドマッチング層を設けてもよい。前記ヘッドマッチング層の材料としては、耐熱性樹脂、無機顔料、などが挙げられる。前記耐熱性樹脂としては、前記保護層中に用いられる耐熱性樹脂と同じものが好適に用いられる。前記無機顔料としては、例えば、炭酸カルシウム、カオリン、シリカ、水酸化アルミニウム、アルミナ、ケイ酸アルミニウム、水酸化マグネシウム、炭酸マグネシウム、酸化マグネシウム、酸化チタン、酸化亜鉛、硫酸バリウム、タルク、等が挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。前記無機顔料の粒径としては、例えば、０．０１〜１０．０μｍが好ましく、０．０５〜８．０μｍがより好ましい。該無機顔料の添加量としては、前記耐熱性樹脂１質量部に対し、０．００１〜２質量部が好ましく、０．００５〜１質量部がより好ましい。
【０１４５】
なお、前記保護層、前記カラー印刷層、前記ヘッドマッチング層中に含まれる樹脂を、熱、紫外線、電子線等により硬化させる場合には、前記感熱層の樹脂を紫外線架橋させるために用いた架橋剤、光重合開始剤、光重合促進剤を添加することが好ましい。
【０１４６】
前記熱可逆記録媒体を製造する方法としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、（１）前記樹脂及び前記有機低分子化合物を溶媒中に溶解乃至分散させた熱可逆記録媒体用組成物を支持体上に塗布し、該溶媒を蒸発させてシート状等にするのと同時に又はその後に架橋する方法、（２）前記樹脂のみを溶解した溶媒に前記有機低分子化合物を分散させた熱可逆記録媒体用組成物を支持体上に塗布し、該溶媒を蒸発させてシート状等にすると同時に又はその後に架橋する方法、（３）溶媒を用いず、前記樹脂と前記有機低分子化合物とを加熱溶融して互いに混合し、この溶融混合物をシート状等に成形して冷却した後に架橋する方法、などが好適に挙げられる。なお、これらにおいて、前記支持体を用いることなく、シート状の熱可逆記録媒体として成形することもできる。
【０１４７】
前記（１）又は（２）において用いる溶剤としては、前記樹脂及び前記有機低分子化合物の種類等によって異なり一概には規定することはできないが、例えば、テトラヒドロフラン、メチルエチルケトン、メチルイソブチルケトン、クロロホルム、四塩化炭素、エタノール、トルエン、ベンゼン、などが挙げられる。
なお、前記有機低分子化合物は、前記感熱層中では粒子状に分散して存在している。
【０１４８】
前記熱可逆記録媒体用組成物には、コーティング材料用としての高度な性能を発現させる目的で、各種顔料、消泡剤、顔料、分散剤、スリップ剤、防腐剤、架橋剤、可塑剤等を添加してもよい。
前記熱可逆記録媒体用組成物の塗布方法としては、特に制限はなく、公知の方法の中から適宜選択することができ、例えば、噴霧コート法、ローラーコート法、バーコート法、エアナイフコート法、刷毛塗り法、ディッピング法、等が挙げられる。
前記熱可逆記録媒体用組成物の乾燥条件としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、室温〜１４０℃の温度で、１０分間〜１時間程度、などが挙げられる。
【０１４９】
前記感熱層における前記樹脂を硬化させるには、加熱、紫外線照射、電子線照射などにより行うことができる。これらの手段で硬化させる方法としては、具体的には、アクリル共重合体（アクリル樹脂）とポリイソシアネート化合物とを反応させることにより硬化させる。
【０１５０】
前記紫外線照射は、公知の紫外線照射装置を用いて行うことができ、該装置としては、例えば、光源、灯具、電源、冷却装置、搬送装置等を備えたものが挙げられる。
前記光源としては、例えば、水銀ランプ、メタルハライドランプ、カリウムランプ、水銀キセノンランプ、フラッシュランプなどが挙げられる。該光源の波長は、前記熱可逆記録媒体用組成物に添加されている光重合開始剤及び光重合促進剤の紫外線吸収波長に応じて適宜選択することができる。
前記紫外線照射の条件としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、前記樹脂を架橋するために必要な照射エネルギーに応じてランプ出力、搬送速度等を決めればよい。
【０１５１】
前記電子線照射は、公知の電子線照射装置を用いて行うことができ、該電子線照射装置は、走査型（スキャンビーム）又は非走査型（エリアビーム）の２種に大別でき、その条件としては照射面積、照射線量等に応じて選択することができる。また、電子線照射条件は、樹脂を架橋するために必要な線量に応じて、電子流、照射幅、搬送スピードを考慮し、下記数式から決定することができる。
Ｄ＝（△Ｅ／△Ｒ）・η・Ｉ／（Ｗ・Ｖ）
前記数式中、Ｄは、必要線量（Ｍｒａｄ）を表す。△Ｅ／△Ｒは、平均エネルギー損失を表す。ηは、効率を表す。Ｉは、電子流（ｍＡ）を表す。Ｗは、照射幅（ｃｍ）を表す。Ｖは、搬送速度（ｃｍ／ｓ）を表す。
なお、工業的には、前記数式を簡略化し、下記数式を用いることが好ましい。
Ｄ・Ｖ＝Ｋ・Ｉ／Ｗ
なお、装置定格は、Ｍｒａｄ・ｍ／ｍｉｎで表され、電子流定格は、２０〜５００ｍＡ程度が選択される。
【０１５２】
前記感熱層における前記樹脂を硬化させた場合、前記感熱層の硬度を向上させることができる。なお、サーマルヘッド等を用い圧力を加えながら同時に加熱する場合には、画像形成−消去を繰り返すうちに、粒子状の前記有機低分子化合物の周囲の前記樹脂が変形し、細かく分散された前記有機低分子化合物が次第に大きな径の粒子となり、光を散乱させる効果が少なくなり（白濁度が低下し）、最終的には、画像コントラストが低下する。したがって、前記感熱層の硬さは該感熱層の耐久性にとって重要であり、該感熱層の硬さが強い程、耐久性が良好である。また、加熱時（１００〜１４０℃）における前記感熱層が硬い方がよく、該感熱層の硬さは、例えば、ＮＥＣ製の薄膜硬度計ＭＨＡ−４００を用いて測定することができる。
【０１５３】
また、前記感熱層中の前記樹脂と前記有機低分子化合物の粒子との界面及び／又は粒子状の該有機低分子化合物の内部に、屈折率と異なる空隙が存在すると、白濁状態での画像濃度が向上し、コントラストを向上させることができる。この場合、該空隙の大きさとしては、不透明状態を検知するために用いる光の波長の１／１０以上であるのが好ましい。
【０１５４】
前記熱可逆記録媒体に形成される画像は、透過画像として視認可能であってもよいし、反射画像としても視認可能であってもよい。
前記反射画像として用いる場合、前記感熱層の背面に光を反射する反射層を設けるのが好ましい。この場合、前記感熱層の厚みを薄くすることができ、該感熱層の厚みを薄くしてもコントラストを上げることができる点で有利である。該反射層としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、Ａｌ、Ｎｉ、Ｓｎ等を蒸着した層、などが挙げられる（例えば、特開昭６４−１４０７９号公報参照）。
【０１５５】
前記熱可逆記録媒体は、熱を選択的に与えることによって前記感熱層を選択的に加熱し、透明地に白濁画像、白濁地に透明画像を形成することができ、その変化は何回も繰り返しすることが可能である。そして、前記感熱層の背面に着色シートを配置すれば、白地に着色シートの色の画像、又は着色シートの色の地に白地の画像を形成することができる。また、ＯＨＰ（オーバーヘッドプロジェクター）などで投影すれば、白濁部は暗部になり、透明部は光が透過しスクリーン上では明部となる。
【０１５６】
前記熱可逆記録媒体に対する画像の形成及び消去は、公知の画像処理装置を用いて行うことができ、後述する本発明の画像処理装置を用いて行うのが好ましい。例えば、前記感熱層は、前記樹脂と該樹脂中に分散された有機低分子化合物とを含み、温度「Ｔ_０」以下の常温では「白濁」状態（不透明）である。この感熱層を加熱していくと、温度「Ｔ_１」から徐々に透明になり始め、温度「Ｔ_２」〜「Ｔ_３」まで加熱すると、該感熱層は「透明」状態となる。この「透明」状態から再び「Ｔ_０」以下の常温に戻しても、該感熱層は「透明」状態のまま維持される。つまり、温度「Ｔ_１」付近から前記樹脂が軟化し始め、温度が上昇するにつれ、該樹脂と前記有機低分子化合物とは共に膨張するものの、該有機低分子化合物の方が前記樹脂より膨張度が大きいため、該有機低分子化合物が、該樹脂との界面における空隙を徐々に減少させ、その結果、透明度が徐々に上がる。温度「Ｔ_２」〜「Ｔ_３」では、前記有機低分子化合物が半溶融状態となり、残存する空隙を、半溶融状態となった該有機低分子化合物が埋めることにより「透明」状態となる。この状態のまま該感熱層が冷却されると、前記有機低分子化合物が比較的高温で結晶化し体積変化が生ずる。このとき、前記樹脂は軟化状態にあるため、前記有機低分子化合物の結晶化による体積変化に追随可能であり、該有機低分子化合物と該樹脂との界面に空隙が生ずることなく、「透明」状態が維持される。また、前記感熱層を温度「Ｔ_４」以上に加熱すると、該感熱層は、最大透明度と最大不透明度との中間の「半透明」状態になる。次に、この温度を下げていくと、「透明」状態となることなく、「白濁」状態（不透明）となる。つまり、前記有機低分子化合物が、温度「Ｔ_４」以上で完全に溶融した後、過冷却状態となり温度「Ｔ_０」より少し高温で結晶化する。その際、前記樹脂が前記有機低分子化合物の結晶化による体積変化に追随不能であり、該有機低分子化合物と該樹脂との界面に空隙が生ずるため、「白濁」状態となる。
【０１５７】
前記画像処理装置としては、例えば、前記熱可逆記録媒体に対し、画像の形成を行うための画像形成手段と、画像の消去を行うための画像消去手段とを備えたものが好適に挙げられ、これらの中でも、処理時間が短かい点で、前記画像形成手段と前記画像消去手段とを兼用した画像形成兼消去手段を備えたものが好ましく、具体的には、サーマルヘッドを用い、該サーマルヘッドに印加するエネルギーを変化させることにより画像を処理可能な画像処理装置、又は、画像形成手段がサーマルヘッドであり、画像消去手段がサーマルヘッド、セラミックヒータ（アルミナ基板上に発熱抵抗体をスクリーン印刷した発熱体）、ホットスタンプ、ヒートローラ、ヒートブロック等の発熱体を接着させる接触押圧型手段、あるいは温風や赤外線などを用いた非接触型手段のうち一つから選択される画像処理装置などが挙げられる。
【０１５８】
本発明の熱可逆記録媒体は、前記可逆表示可能な感熱層と情報記憶部とを、同一のカードに設け（一体化させ）、該情報記憶部の記憶情報の一部を感熱層に表示することにより、カード所有者等は特別な装置がなくてもカードを見るだけで情報を確認することができ、利便性に優れる。
なお、前記情報記憶部としては、特に制限はないが、例えば、磁気記録、ＩＣ、非接触ＩＣ、光メモリが好ましい。前記感熱層としては、通常用いられる酸化鉄、バリウムフェライト等と塩ビ系やウレタン系樹脂、ナイロン系樹脂等を用い、支持体上に塗工形成されるか、又は蒸着・スパッタリング等の方法により樹脂を用いず形成される。前記感熱層は支持体における該感熱層とは反対側の面に設けてもよいし、支持体と該感熱層との間、該感熱層上の一部に設けてもよい。また、表示に用いる可逆感熱材料をバーコード、２次元コード等により記憶部に用いてもよい。これらの中では磁気記録、ＩＣが更に好ましい。
【０１５９】
本発明の熱可逆記録媒体によると、サーマルヘッドを用いてミリ秒単位の極小時間加熱した場合でも十分に画像が消去され、画像形成経時後に消去エネルギーが変化しないため、十分な消去性が維持され、高温で長時間放置しても保存性、コントラスト、視認性等に優れた画像が形成される。
前記熱可逆記録媒体は、リライタブルな各種ポイントカード等に好適に使用することができ、以下の本発明の熱可逆記録ラベル、熱可逆部材、画像処理装置及び画像処理方法などに特に好適に使用することができる。
【０１６０】
（熱可逆記録ラベル及び熱可逆記録部材）
本発明の熱可逆記録ラベルは、本発明の前記熱可逆記録媒体における画像を形成する面と反対側の面（支持体の上に前記感熱層を有する場合には、該支持体における前記感熱層を形成した面の反対側の面）に接着剤層及び粘着剤層の少なくともいずれかを有してなり、更に必要に応じて適宜選択したその他の層を有してなる。
【０１６１】
前記接着剤層乃至前記粘着剤層の形状、構造、大きさ等については、特に制限はなく、目的に応じて適宜選択することができ、例えば、前記形状としては、シート状、フィルム状などが挙げられ、前記構造としては、単層構造であってもよいし、積層構造であってもよく、前記大きさとしては、前記感熱層よりも大きくてもよいし、小さくてもよい。
前記接着剤層乃至前記粘着剤層の材料としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、ユリア樹脂、メラミン樹脂、フェノール樹脂、エポキシ樹脂、酢ビ系樹脂、酢酸ビニル−アクリル系共重合体、エチレン−酢酸ビニル共重合体、アクリル系樹脂、ポリビニルエーテル系樹脂、塩化ビニル−酢酸ビニル系共重合体、ポリスチレン系樹脂、ポリエステル系樹脂、ポリウレタン系樹脂、ポリアミド系樹脂、塩素化ポリオレフィン系樹脂、ポリビニルブチラール系樹脂、アクリル酸エステル系共重合体、メタクリル酸エステル系共重合体、天然ゴム、シアノアクリレート系樹脂、シリコーン系樹脂、などが挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよく、また、ホットメルトタイプでもよく、また、剥離紙を用いてもよいし、無剥離紙タイプでもよい。
【０１６２】
前記熱可逆記録ラベルが前記接着剤層及び前記粘着剤層の少なくともいずれかを有していると、前記感熱層の塗布が困難な磁気ストライプ付塩化ビニル製カード等の厚手基板の全面又は一部に、貼付可能であり、磁気に記憶された情報の一部を表示可能とすることができる。
前記熱可逆記録ラベルは、フレキシブルディスク（ＦＤ）、ＭＤ、ＤＶＤ−ＲＡＭ、等の記録情報が書換可能なディスクを内蔵したディスクカートリッジ上の表示ラベルの代替品とすることができる。
【０１６３】
図５は、本発明の熱可逆記録ラベル１０をＭＤのディスクカートリッジ７０上に貼付した例を示す。この場合、ＭＤへの記憶内容の変更に応じて自動的に表示内容を変更するなどの用途への応用が可能である。なお、ＣＤ−ＲＷ等のディスクカートリッジを用いないディスクの場合には、直接ディスクに本発明の前記熱可逆記録ラベルを貼付してもよい。
図６は、本発明の熱可逆記録ラベル１０をＣＤ−ＲＷ７１上に貼付した例を示す。この場合、ＣＤ―ＲＷの変わりにＣＲ−Ｒ等の追記型ディスク上に、前記熱可逆記録ラベルを貼付して、そのＣＤ−Ｒに追記した記憶情報の一部を替換え表示することが可能である。
【０１６４】
図７は、ＡｇＩｎＳｂＴｅ系の相変化形記憶材料を用いた光情報記録媒体（ＣＤ−ＲＷ）上に、本発明の前記熱可逆記録ラベルを貼付した例である。このＣＤ−ＲＷの基本的な構成は、案内溝を有する基体１１１上に、第１誘電体層１１０、光情報記億層１０９、第２誘電体層１０８、反射放熱層１０７、中間層１０６がこの順に設けられ、基体１１１の裏面にハードコート層１１２を有する。このＣＤ―ＲＷの中間層１０６上に、本発明の熱可逆記録ラベル１０が貼付されている。熱可逆記録ラベル１０は、接着剤層及び粘着剤のいずれかの層１０５、支持体１０４、光反射層１０３、可逆感熱層１０２、及び保護層１０１をこの順に有してなる。なお、前記誘電体層は必ずしも前記感熱層の両側に設ける必要はないが、前記基体がポリカーボネート樹脂のように耐熱性が低い材料の場合には、第一誘電体層１１０を設けることが望ましい。
【０１６５】
図８は、本発明の熱可逆記録ラベル１０をビデオカセット７２上に貼付した例を示す。この場合、ビデオテープカセットへの記憶内容の変更に応じて自動的に表示内容を変更するなどの用途への応用が可能である。
【０１６６】
前記熱可逆記録機能を、カード、ディスク、ディスクカートリッジ、及びテープカセット上に設ける方法としては、前記熱可逆記録ラベルを貼る方法以外に、それらの上に前記感熱層を直接塗布する方法、予め別の支持体上に前記感熱層を形成しておき、前記カード、前記ディスク、前記ディスクカートリッジ及び前記テープカセット上に該感熱層を転写する方法、などが挙げられる。前記感熱層を転写する方法の場合には、前記感熱層上にホットメルトタイプなどの前記接着層や前記粘着層を設けておいてもよい。前記カード、前記ディスク、前記ディスクカートリッジ及びテープカセットなどのように剛直なものの上に前記熱可逆記録ラベルを貼付したり、前記感熱層を設ける場合には、サーマルヘッドとの接触性を向上させて画像を均一に形成するために弾力があり、クッションとなる層、又はシートを剛直な基体とラベル若しくは前記感熱層の間に設けることが好ましい。
【０１６７】
本発明の熱可逆記録媒体は、例えば、図９Ａに示すように、支持体１１上に、可逆性感熱層１３、及び保護層１４を設けてなるフィルム、図９Ｂに示すように、支持体１１上に、アルミニウム反射層１２、可逆性感熱層１３、及び保護層１４を設けてなるフィルム、図９Ｃに示すように、支持体１１上に、アルミニウム反射層１２、可逆性感熱層１３及び保護層１４を設け、支持体１１の裏面に磁気感熱層１６を設けてなるフィルム、などの態様をとることができる。
これら各態様のフィルム（熱可逆記録媒体）は、例えば、図１０Ａに示すように、印刷表示部２３を有する熱可逆記録カード２１に加工した形態として使用することができる。なお、図１０Ｂに示すように、カードの裏面側は磁気記録部２４が形成されている。
【０１６８】
また、図１１Ａに示す熱可逆記録部材（カード）は、支持体上に、アルミニウム反射層、可逆性感熱層、保護層を設けてなるフィルムをカード状に加工し、ＩＣチップを納める窪み部２５を形成すると共に、カード状に加工したものである。図１１Ａでは、カード状の熱可逆記録媒体に書き換え記録部２６がラベル加工されるとともに、カートの裏面側には所定箇所にＩＣチッブ埋め込み用窪み部２５が形成されている。この窪み部２５に、図１１Ｂに示すようにウエハ２３１が組込まれて固定される。ウエハ２３１は、ウエハ基板２３２上に、集積回路２３３が設けられると共に、集積回路２３３に電気的に接続されている複数の接触端子２３４がウエハ基板２３２に設けられる。この接触端子２３４はウエハ基板２３２の裏面側に露出しており、専用のプリンタ（リーダライタ）が、接触端子２３４に電気的に接触して所定の情報を読み出したり書き換えたりできるように構成されている。
【０１６９】
次に、前記熱可逆記録カードについて図１２を参照しつつ、その機能について説明する。図１２Ａは、集積回路２３３を示す概略の構成ブロック図である。また、図１２Ｂは、ＲＡＭの記憶データの一例を示す構成ブロック図である。集積回路２３３は、例えば、ＬＳＩで構成されており、その中には制御動作を所定の手順で実行することのできるＣＰＵ２３５と、ＣＰＵ２３５の動作プログラムデータを格納するＲＯＭ２３６と、必要なデータの書き込み及び読み出しができるＲＡＭ２３７を含む。更に、集積回路２３３は、入力信号を受けてＣＰＵ２３５に入力データを与えるとともにＣＰＵ２３５からの出力信号を受けて外部に出力する入出力インターフェース２３８と、図示を省略しているが、パワーオンリセット回路、クロック発生回路、パルス分周回路（割込パルス発生回路）、アドレスデコーダ回路とを含む。
ＣＰＵ２３５は、パルス分周回路から定期的に与えられる割込パルスに応じて、割込制御ルーチンの動作を実行することが可能となる。また、アドレスデコード回路は、ＣＰＵ２３５からのアドレスデータをデコードし、ＲＯＭ２３６、ＲＡＭ２３７、入出力インターフェース２３８にそれぞれ信号を与える。入出力インターフェース２３８には、複数（図１２中では８個）の接触端子２３４が接続されており、前記専用プリンタ（リーダライタ）からの所定データがこの接触端子２３４から入出力インターフェース２３８を介してＣＰＵ２３５に入力される。ＣＰＵ２３５は、入力信号に応答して、かつＲＯＭ２３６内に格納されたプログラムデータに従って、各動作を行い、かつ所定のデータ、信号を入出力インターフェース２３８を介してシートリーダライタに出力する。
【０１７０】
図１２Ｂに示すように、ＲＡＭ２３７は、複数の記憶領域２３９ａ〜２３９ｇを含む。例えば、領域２３９ａにはシート番号が記憶されている。例えば、記憶領域２３９ｂには、シート管理者の氏名、所属、電話番号等のＩＤデータが記憶されている。例えば、記憶領域２３９ｃには、使用者の使用しうる残存余白又は取り扱いに関する情報が記憶されている。例えば、記憶領域２３９ｄ、記憶領域２３９ｅ、記憶領域２３９ｆ及び記憶領域２３９ｇには、前管理責任者、前使用者に関する情報、などが記憶される。
【０１７１】
本発明の前記熱可逆記録ラベル及び前記熱可逆記録部材の少なくともいずれかは、特に制限はなく、各種画像処理方法及び画像処理装置により、画像処理することができが、後述する本発明の画像処理装置を用いて好適に画像の形成及び消去を行うことができる。
【０１７２】
（画像処理方法及び画像処理装置）
本発明の画像処理装置は、画像形成手段及び画像消去手段の少なくともいずれかを有し、更に必要に応じて適宜選択したその他の手段、例えば、搬送手段、制御手段等を有してなる。
本発明の画像処理方法は、前記本発明の前記熱可逆記録媒体を加熱して画像の形成及び消去の少なくともいずれかを行い、更に必要に応じて適宜選択したその他の工程、例えば、搬送工程、制御工程等を有してなる。
【０１７３】
本発明の画像処理方法は、本発明の画像処理装置により好適に実施することができ、前記本発明の熱可逆記録媒体を加熱して画像の形成及び画像の消去の少なくともいずれかは前記画像形成手段及び画像消去手段の少なくともいずれかにより行うことができ、前記その他の工程は前記その他の手段により行うことができる。
【０１７４】
−画像形成手段及び画像消去手段−
前記画像形成手段は、本発明の前記熱可逆記録媒体を加熱して画像を形成する手段である。また、前記画像消去手段は、前記本発明の熱可逆記録媒体を加熱して画像を消去する手段である。
前記画像形成手段としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、サーマルヘッド、レーザなどが挙げられる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。
前記画像消去手段としては、本発明の前記熱可逆記録媒体を加熱して画像を消去する手段であり、例えば、ホットスタンプ、セラミックヒータ、ヒートローラ、熱風等や、サーマルヘッド、レーザ等が挙げられる。これらの中では、セラミックヒータが好適である。前記セラミックヒータを用いることにより、装置が小型化でき、かつ安定した消去状態が得られ、コントラストのよい画像が得られる。前記セラミックヒータの設定温度としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、１１０℃以上が好ましく、１１２℃以上がより好ましく、１１５℃以上が特に好ましい。
【０１７５】
前記サーマルヘッドを用いることにより、更に小型化が可能となり、また、消費電力を低減することが可能であり、バッテリー駆動のハンディタイプの装置も可能となる。また、前記画像の記録及び消去を兼ねて一つのサーマルヘッドとすることができ、この場合は、更に小型化が可能となる。一つのサーマルヘッドで記録と消去とを行う場合、一旦前画像を全部消去した後、改めて新しい画像を記録してもよいし、画像毎にエネルギーを変えて一度に前の画像を消去し、新しい画像を記録していくオーバーライト方式も可能である。該オーバーライト方式においては、前記画像の記録及び消去を合わせた時間が少なくなり、記録のスピードアップにつながる。
前記感熱層と情報記憶部とを有する熱可逆記録部材（カード）を用いる場合、上記装置には、情報記億部の記億を読み取る手段と書き換える手段なども含まれる。
【０１７６】
前記搬送手段は、前記熱可逆記録媒体を順次搬送する機能を有している限り特に制限はなく、目的に応じて適宜選択することができ、例えば、搬送ベルト、搬送ローラ、搬送ベルトと搬送ローラとの組合せ、などが挙げられる。
【０１７７】
前記制御手段は、前記各工程を制御する機能を有する限り特に制限はなく、各工程の制御を行うことができ、例えば、シークエンサー、コンピュータ等の機器が挙げられる。
【０１７８】
本発明の画像処理装置により本発明の画像処理方法を実施する一の態様について、図１３を参照しながら説明する。図１３に示す画像処理装置は、前記加熱処理手段としてのサーマルヘッド５３と、セラミックヒータ３８と、磁気ヘッド３４と、搬送ローラ３１、４０及び４７とを備えている。
図１３Ａに示すように、この画像処理装置においては、最初、記録媒体の磁気感熱層に記億された情報を磁気ヘッドで読み取る。次に、セラミックヒータで可逆性感熱層に記録された画像を加熱消去する。更に、磁気ヘッドで読み取られた情報をもとにして、処理された新たな情報がサーマルヘッドにより、可逆性感熱層に記録される。その後、磁気感熱層の情報も新たな情報に書き替えられる。
図１３Ａに示す画像処理装置においては、感熱層の反対側に磁気感熱層を設けた熱可逆記録媒体１は往復の矢印で図示されている搬送路に沿って搬送され、或いは搬送路に沿って装置内を逆方向に搬送される。熱可逆記録媒体１は、磁気ヘッド３４及び搬送ローラ３１間で磁気感熱層に磁気記録乃至消去され、セラミックヒータ３８及び搬送ローラ４０間で画像消去のため加熱処理され、サーマルヘッド５３及び領域搬送ローラ４７間で画像形成される。その後、装置外に搬出される。先に説明したように、セラミックヒータ３８の設定温度は１１０℃以上が好ましく、１１２℃以上が更に好ましく、１１５℃以上が特に好ましい。ただし、磁気記録の書替えはセラミックヒータによる画像消去の前であってもよいし、後であってもよい。また、所望により、セラミックヒータ３８及び搬送ローラ４０間を通過後、又はサーマルヘッド５３及び搬送ローラ４７間を通過後、搬送路を逆方向に搬送される。セラミックヒータ３８よる再度の熱処理、サーマルヘッド５３による再度の印字処理を施すことができる。
【０１７９】
図１３Ｂの画像処理装置においては、出入口３０から挿入された熱可逆記録媒体１は、一点破線で図示されている搬送路５０に沿って進行し、或いは搬送路５０に沿って装置内を逆方向に進行する。出入口３０から挿入された熱可逆記録媒体１は、搬送ローラ３１及びガイドローラ３２により記録装置内を搬送される。搬送路５０の所定位置に到達するとセンサ３３により制御手段３４ｃを介してその存在を認識され、磁気ヘッド３４とプラテンローラ３５との間で磁気感熱層に磁気記録或いは記録消去され、ガイドローラ３６及び搬送ローラ３７間を通過し、ガイドローラ３９及び搬送ローラ４０間を通過し、センサ４３により、セラミックヒータ制御手段３８ｃを介してその存在を認識して作動するセラミックヒータ３８とプラテンローラ４４との間で画像消去のため加熱処理され、搬送ローラ４５、４６及び４７により搬送路５０内を搬送され、所定位置にてセンサ５１により、サーマルヘッド制御手段５３ｃを介してその存在を認識して作動するサーマルヘッド５３及びプラテンローラ５２間で画像形成され、搬送路５６ａから搬送ローラ５９及びガイドローラ６０により出口６１を経て装置外に搬出される。ここで、セラミックヒータ３８の設定温度としては、特に制限はなく、目的に応じて適宜選択することができ、上述したように、１１０℃以上が好ましく、１１２℃以上が更に好ましく、１１５℃以上が特に好ましい。
【０１８０】
また、所望により、搬送路切換手段５５ａを切り替えることにより搬送路５６ｂに導き、熱可逆記録媒体１の押圧により入力するリミットスイッチ５７ａの作動により逆方向に動く搬送ベルト５８によって、熱可逆記録媒体１を再度、サーマルヘッド５３及びプラテンローラ５２間で熱処理した後、搬送路切換手段５５ｂを切り替えることにより通じる搬送路４９ｂ、リミットスイッチ５７ｂ、搬送ベルト４８を介して順方向に搬送し、搬送路５６ａから搬送ローラ５９及びガイドローラ６０により出口６１を経て装置外に搬出することができる。更に、このような分岐した搬送路及び搬送切換手段は、セラミックヒータ３８の両側に設けることもできる。その場合には、センサ４３ａを、プラテンローラ４４と搬送ローラ４５との間に設けることが望ましい。
【０１８１】
本発明の画像処理装置及び画像処理方法によると、短時間で高速で処理可能であり、サーマルヘッド等により短時間の加熱時間でも、画像の形成及び消去を十分に行うことができ、長期保存後においても画像の消去性に優れ、高コントラストな画像を形成することができる。
【０１８２】
【実施例】
以下、本発明の実施例について説明するが、本発明はこれらの実施例に何ら限定されるものではない。
【０１８３】
（合成例１）
−アクリル樹脂（Ａ１）の合成−
スチレン１３２質量部、メタクリル酸メチル２９７質量部、アクリル酸２−エチルヘキシル５４質量部、アクリル酸４−ヒドロキシブチル１０８質量部、及びメタクリル酸９質量部を混合してモノマー混合物を作製した。
２リットルの四つ口フラスコ中に、溶剤としての酢酸ブチル３６０質量部、及び前記モノマー混合物５４０質量部を仕込んだ。残りの前記モノマー混合物に開始剤としてのカヤエステルＯ（化薬アクゾ社製）を６．６質量部添加して滴下用モノマー混合物を準備した。フラスコ内温度１２０℃に保持した後に前記滴下用モノマー混合物を４時間掛けて滴下し、滴下終了後に酢酸ブチル３０質量部を投入した。フラスコ内温度１２０℃のまま１時間保持し、追加開始剤としてのカヤエステルＯを１．２質量部と酢酸ブチルを３０質量部とからなる開始剤混合物を１時間置きに３回一括添加した。更に、フラスコ内温度１２０℃のまま１時間保持した後、フラスコ内温度を８０℃以下に冷却した時点でメチルエチルケトン（ＭＥＫ）３６０質量部を投入し、冷却して合成例１のアクリル樹脂（Ａ１）を合成した。なお、得られたアクリル樹脂（Ａ１）は缶詰して保存した。
得られたアクリル樹脂（Ａ１）の特性値は、粘度（気泡粘度計）が−Ｊ、加熱残分が４２．１質量％、酸価が４．１ｍｇＫＯＨ／ｇ、水酸基価が７０、重量平均分子量が３９，０００であった。また、アクリル樹脂の計算により求めたガラス転移温度（Ｔｇ）は４５℃、計算により求めた屈折率は１．５１１５であった。
【０１８４】
（実施例１）
−熱可逆記録媒体の作製−
まず、大日本インキ工業社製の磁気原反（メモリディック、ＤＳ−１７１１−１０４０：１８８μｍの厚みの透明ＰＥＴフィルム上に磁気感熱層及びセルフクリーニング層を塗工したもの）のＰＥＴフィルム側に、約４００Åの厚みとなるようにアルミニウム（Ａｌ）を真空蒸着して光反射層を設けた。光反射層の上に、塩化ビニル−酢酸ビニル−リン酸エステル共重合体（電気化学工業社製、デンカビニール＃１０００Ｐ）１０質量部、メチルエチルケトン４５質量部、及びトルエン４５質量部からなる接着層用塗布液を塗布し、加熱乾燥し、約０．５μｍの厚みとなるように接着層を設けた。次に、接着層上に、ステアリン酸ステアリル（日本油脂社製、Ｍ９６７６）５質量部、エイコサン２酸（岡村製油社製、ＳＬ−２０−９０）５質量部、合成例１のアクリル樹脂（Ａ１）２７質量部、イソシアネート化合物（日本ポリウレタン製、コロネート２２９８−９０Ｔ）３質量部、キシレン４０質量部、及びテトラヒドロフラン１６０質量部からなる感熱層用塗布液を塗布し、１３０℃にて３分間加熱乾燥して約１０μｍの厚みとなるように感熱層を設け、６０℃にて４８時間加熱して、硬化した。次に、感熱層上に、ウレタンアクリレート系紫外線硬化性樹脂（大日本インキ化学社製：ユニデックＣ７−１５７）の７５質量％酢酸ブチル溶液１０質量部、及びイソプロピルアルコール１０質量部からなる保護層用塗布液をワイヤーバーで塗布し、加熱乾燥した後、８０Ｗ／ｃｍの紫外線ランプで硬化させて、約２μｍの厚みの保護層を設けた。
以上により、実施例１の熱可逆記録媒体を作製した。
【０１８５】
（合成例２）
−アクリル樹脂（Ａ２）の合成−
合成例１において、前記モノマー混合物を、スチレン１３２質量部、メタクリル酸メチル３０９質量部、アクリル酸２−エチルヘキシル４２質量部、アクリル酸４−ヒドロキシブチル１０８質量部、メタクリル酸９質量部とのモノマー混合物６００質量部に変えた以外は、合成例１と同様にして、合成例２のアクリル樹脂（Ａ２）を合成した。
得られたアクリル樹脂（Ａ２）の溶液特性値は、粘度（気泡粘度計）が−Ｇ、加熱残分が４２．１質量％、酸価が４．１ｍｇＫＯＨ／ｇ、水酸基価が７０、重量平均分子量が４０，０００であった。また、アクリル樹脂（Ａ２）の計算により求めたガラス転移温度（Ｔｇ）は５０℃、計算により求めた屈折率は１．５１１５であった。
【０１８６】
（実施例２）
−熱可逆記録媒体の作製−
実施例１において、前記合成例１のアクリル樹脂（Ａ１）を前記合成例２のアクリル共重合体（Ａ２）に代えた以外は、実施例１と同様にして実施例２の熱可逆記録媒体を作製した。
【０１８７】
（合成例３）
−アクリル樹脂（Ａ３）の合成−
合成例１において、前記モノマー混合物を、スチレン１５０質量部、メタクリル酸メチル１２３質量部、メタクリル酸ベンジル１３２質量部、アクリル酸２−エチルヘキシル７８質量部、アクリル酸４−ヒドロキシブチル１０８質量部、メタクリル酸９質量部のモノマー混合物６００質量部に変えた以外は、合成例１と同様にして、合成例３のアクリル樹脂（Ａ３）を合成した。
得られたアクリル樹脂（Ａ３）の溶液特性値は、粘度（気泡粘度計）が−Ｄ、加熱残分が４１．５質量％、酸価が４．５ｍｇＫＯＨ／ｇ、水酸基価が７０、重量平均分子量が３８，０００であった。また、アクリル樹脂の計算により求めたガラス転移温度（Ｔｇ）は３０℃、計算により求めた屈折率は１．５３０８であった。
【０１８８】
（実施例３）
−熱可逆記録媒体の作製−
実施例１において、前記アクリル樹脂（Ａ１）をアクリル樹脂（Ａ３）に代え、前記イソシアネート化合物をコロネートＨＬ（日本ポリウレタン製）に代えた以外は、実施例１と同様にして、実施例３の熱可逆記録媒体を作製した。
【０１８９】
（合成例４）
−アクリル樹脂（Ａ４）の合成−
合成例１において、前記モノマー混合物を、スチレン１２０質量部、メタクリル酸メチル１５３質量部、メタクリル酸ベンジル１８０質量部、アクリル酸２−エチルヘキシル３０質量部、アクリル酸４−ヒドロキシブチル１０８質量部、及びメタクリルル酸９質量部のモノマー混合物６００質量部に変えた以外は、合成例１と同様にして、合成例４のアクリル樹脂（Ａ４）を合成した。
得られたアクリル樹脂（Ａ４）の溶液特性値は、粘度（気泡粘度計）が−Ｒ、加熱残分が５０．９質量％、酸価が５．１ｍｇＫＯＨ／ｇ、Ｔｇが４０℃、水酸基価が７０、重量平均分子量が４１，０００であった。また、アクリル樹脂の計算により求めた屈折率は１．５３２であった。
【０１９０】
（実施例４）
−熱可逆記録媒体の作製−
実施例１において、前記アクリル樹脂（Ａ１）をアクリル樹脂（Ａ４）に代えた以外は、実施例１と同様にして、実施例４の熱可逆記録媒体を作製した。
【０１９１】
（合成例５）
−アクリル樹脂（Ａ５）の合成例−
合成例１において、前記モノマー混合物を、スチレン１２５質量部、メタクリル酸メチル２９１質量部、アクリル酸２−エチルヘキシル６７質量部、アクリル酸４−ヒドロキシブチル１０８質量部、及びメタクリル酸９質量部とのモノマー混合物６００質量部に変えた以外は、合成例１と同様にして、合成例５のアクリル樹脂（Ａ５）を合成した。
得られたアクリル共重合体（Ａ５）の溶液特性値は、粘度（気泡粘度計）が−Ｃ、加熱残分が４０．４質量％、酸価が４．２ｇＫＯＨ／ｇ、Ｔｇが４０℃、水酸基価が７０、重量平均分子量が３７，８００であった。アクリル樹脂の計算により求めた屈折率は１．５１１３であった。
【０１９２】
（実施例５）
−熱可逆記録媒体の作製−
実施例１において、前記アクリル樹脂（Ａ１）を前記アクリル樹脂（Ａ５）に代えた以外は、実施例１と同様にして、実施例５の熱可逆記録媒体を作製した。
【０１９３】
（合成例６）
−アクリル樹脂（Ａ６）の合成−
合成例１において、前記モノマー混合物を、スチレン１００質量部、メタクリル酸メチル２９０質量部、アクリル酸ブチル９３質量部、アクリル酸４−ヒドロキシブチル１０８質量部、及びメタクリル酸９質量部とのモノマー混合物６００質量部に変えた以外は、合成例１と同様にして、合成例６のアクリル樹脂（Ａ６）を合成した。
得られたアクリル樹脂（Ａ６）の溶液特性値は、粘度（気泡粘度計）が−Ｄ、加熱残分が４０．２質量％、酸価４．１ｍｇＫＯＨ／ｇ、Ｔｇは４０℃、重量平均分子量は４２，０００であった。アクリル樹脂の計算により求めた屈折率は１．５１１６であった。
【０１９４】
（実施例６）
−熱可逆記録媒体の作製−
実施例１において、前記アクリル樹脂（Ａ１）を前記アクリル樹脂（Ａ６）代え、前記イソシアネート化合物をコロネートＨＬ（日本ポリウレタン製）に代えた以外は、実施例１と同様にして、実施例６の熱可逆記録媒体を作製した。
【０１９５】
（合成例７）
−アクリル樹脂（Ａ７）の合成−
合成例１において、前記モノマー混合物を、スチレン２１０質量部、メタクリル酸メチル２２９．２質量部、アクリル酸２−エチルヘキシル９０質量部、アクリル酸４−ヒドロキシブチル５８．８質量部、及びメタクリル酸１２質量部のモノマー混合物に変えた以外は、合成例１と同様にして、合成例７のアクリル樹脂（Ａ７）を合成した。
得られたアクリル樹脂（Ａ７）の溶液特性値は、粘度（気泡粘度計）が−Ｄ、加熱残分が４０質量％、酸価４．３ｍｇＫＯＨ／ｇ、ガラス転移温度（Ｔｇ）は５０℃、重量平均分子量は４０，０００であった。アクリル樹脂の計算により求めた屈折率は１．５２５７であった。
【０１９６】
（実施例７）
−熱可逆記録媒体の作製−
まず、大日本インキ工業社製の磁気原反（メモリディック、ＤＳ−１７１１−１０４０：厚み１８８μｍの透明ＰＥＴフィルム上に磁気感熱層及びセルフクリーニング層を塗工したもの）のＰＥＴフィルム側に、約４００Åの厚みとなるようにアルミニウム（Ａｌ）を真空蒸着して光反射層を設けた。次に、光反射層の上に、塩化ビニル−酢酸ビニル−リン酸エステル共重合体（電気化学工業社製、デンカビニール＃１０００Ｐ）１０質量部、メチルエチルケトン４５質量部、及びトルエン４５質量部からなる接着層用塗布液を塗布し、加熱乾燥し、約０．５μｍ厚みの接着層を設けた。次に、合成例７のアクリル樹脂（Ａ７）５０２質量部に対し、ステアリン酸ステアリル（ミヨシ油脂社製、ＳＳ９６）６３質量部を添加し、下記構造式（Ａ）で表されるイソシアネート化合物８質量部、下記構造式（Ｂ）で表されるイソシアネート化合物９質量部、及びメチルエチルケトン２２０質量部をガラス瓶中に直径約２ｍｍのセラミックビーズを入れてペイントシェーカー（浅田鉄工製）を用い３５時間分散した分散液Ａを調製した。
【０１９７】
【化２８】

【０１９８】
次に、前記分散液Ａ　４００質量部に、メチルエチルケトン２０９質量部、イソシアネート化合物（Ｅ−４０２−９０Ｔ；旭化学製）３５質量部、ｏ−キシレン１１５質量部、及びレベリング剤（ＳＴ１０２ＰＡ　ＭＥＫ１質量％溶液）４質量部からなる分散溶液を前記接着層上に塗布し、１２５℃にて１分間加熱乾燥して約１１μｍの厚みとなるように感熱層を設けた後、５０℃にて４８時間加熱して、硬化した。次に、感熱層上に実施例１と同様にして保護層を形成した。
以上により、実施例７の熱可逆記録媒体を製造した。
【０１９９】
（実施例８）
−熱可逆記録媒体の作製−
実施例７において、前記感熱層用塗布液において、前記構造式（Ａ）及び（Ｂ）で表されるイソシアネート化合物を添加しない以外は、実施例７と同様にして、実施例８の熱可逆記録媒体を作製した。
【０２００】
（比較例１）
−熱可逆記録媒体の作製−
まず、大日本インキ工業社製磁気原反（メモリディック、ＤＳ−１７１１−１０４０：厚み１８８μｍの透明ＰＥＴフィルム上に磁気感熱層及びセルフクリーニング層を塗工したもの）のＰＥＴフィルム側に、約４００Åの厚みとなるようにアルミニウム（Ａｌ）を真空蒸着して光反射層を設けた。次に、光反射層の上に、塩化ビニル−酢酸ビニル−リン酸エステル共重合体（電気化学工業社製、デンカビニール＃１０００Ｐ）１０質量部、メチルエチルケトン４５質量部、及びトルエン４５質量部からなる接着層用塗布液を塗布し、加熱乾燥し、約０．５μｍ厚みの接着層を設けた。次に、接着層上に、塩化ビニル−酢酸ビニル共重合体（日信化学工業製、ソルバインＣ、塩化ビニル／酢酸ビニル＝８７／１３（モル比））１２０質量部、ステアリン酸ヘキサデシル４０質量部、ドデカンニ酸１０質量部、ステアロン（１８−ペンタトリアコンタノン）１０質量部、及びＴＨＦ９４５質量部からなる感熱層用塗布液を塗布し、１２０℃にて２分間加熱乾燥して約１０μｍの厚みとなるように感熱層を設けた後、６０℃にて４８時間加熱して、硬化した。次に、感熱層上に、ウレタンアクリレート系紫外線硬化性樹脂（大日本インキ化学社製：ユニデックＣ７−１５７）の７５質量％酢酸ブチル溶液１０質量部、及びイソプロピルアルコール１０質量部からなる保護層用塗布液をワイヤーバーで塗布し、加熱乾燥後、８０Ｗ／ｃｍの紫外線ランプで硬化させ、約２μｍの厚みとなるように保護層を設けた。
以上により、比較例１の熱可逆記録媒体を作製した。
【０２０１】
（比較例２）
−熱可逆記録媒体の作製−
比較例１において、感熱層用塗布液として、塩化ビニル−酢酸ビニル共重合体（日信化学工業製、ソルバインＣ、塩化ビニル／酢酸ビニル＝８７／１３（モル比））８０質量部、ジヘキサデシルチオエーテル２８質量部、ドデカンニ酸１２質量部、及びＴＨＦ６３０質量部からなる感熱層用塗布液を用いた以外は、比較例１と同様にして、比較例２の熱可逆記録媒体を作製した。
【０２０２】
（比較例３）
−熱可逆記録媒体の作製−
比較例１において、前記接着層上に、ＶＭＣＨ（ＵＣＣ社製、塩化ビニルが８５〜８７質量％、ＭＡ（マレイン酸）が０．７〜１質量％、酢酸ビニルがバランスの共重合体）５０質量部、ドデカンニ酸２５質量部、ステアリルべヘネート６０質量部、１−９ノナンジオールアクリレート２０質量部、低Ｔｇアクリル系樹脂（東亞合成化学製、Ｓ２０４０、固形分３０質量％）１２０質量部、イルガキュア１８４（チバガイギー社製の硬化剤）１０質量部、ジメチルポリシロキサン−ポリオキシアルキレン共重合体レベリング剤（東レダウコーニングシリコン製、ＳＴ１０２ＰＡ）１０質量部、及びＴＨＦ９６２質量部からなる感熱層用塗布液を塗布し、１３０℃にて１分間加熱乾燥した後８０Ｗ／ｃｍ×２灯のＵＶ照射を行い、約１０μｍの厚みとなるように感熱層を設けた後、６０℃にて４８時間加熱して、硬化した以外は、比較例１と同様にして、比較例３の熱可逆記録媒体を作製した。
【０２０３】
（比較例４）
−熱可逆記録媒体の作製−
比較例１において、感熱層用塗布液として、ＶＹＨＨ（ＵＣＣ社製、塩ビニルが８５〜８７質量％、酢酸ビニルがバランスの共重合体）１２０質量部、ベヘニルべヘネート５０質量部、ドデカンニ酸１０質量部、低Ｔｇアクリル系樹脂（東亞合成化学製、Ｓ２０４０、固形分３０質量％）２４０質量部、イソシアネート化合物（日本ポリウレタン製、コロネートＬ）１０質量部、ジメチルポリシロキサン−ポリオキシアルキレン共重合体レベリング剤（東レダウコーニングシリコン製、ＳＴ１０２ＰＡ）１０質量部、及びＴＨＦ１１８３質量部からなる感熱層用塗布液に代えた以外は、比較例１と同様にして、比較例４の熱可逆記録媒体を作製した。
【０２０４】
（比較例５）
−熱可逆記録媒体の作製−
まず、塩化ビニル系共重合体（日本ゼオン社製、ＭＲ１１０）をＴＨＦに溶解した固形分１５質量％溶液５００質量部に対し、ＨＯＯＣ（ＣＨ_２）_５ＮＨＣＯ（ＣＨ_２）ＣＯＮＨ（ＣＨ_２）_５ＣＯＯＨ_１５を添加し、ガラス瓶中に直径約２ｍｍのセラミックビーズを入れてペイントシェーカー（浅田鉄工製）を用い４８時間分散して分散液Ａを調製した。
ベヘン酸（ミヨシ油脂社製、ベヘン酸９５）１１０質量部、エイコサンニ酸（岡村製油社製、ＳＬ−２０−９０）２５質量部、塩化ビニル系共重合体（日本ゼオン社製、ＭＲ１１０）３００質量部、ＴＨＦ１７０質量部、及びｏ−キシレン６０質量部を常法により混合して、分散液Ｂを調製した。
次に、前記分散液Ａ　８質量部、前記分散液Ｂ　２７０質量部、及びイソシアネート化合物（日本ポリウレタン工業社製、２２９８−９０Ｔ）６０質量部を混合して感熱層用塗布液を調製した。
次に、比較例１において、前記感熱層用塗布液を用いた以外は、比較例１と同様にして、比較例５の熱可逆記録媒体を作製した。
【０２０５】
（比較例６）
−熱可逆記録媒体の作製−
比較例１において、前記接着層上に、１，１８−オクタデカジカルボン酸ドデシル（ミヨシ油脂社製）４．７５質量部、エイコサン２酸（岡村製油社製、ＳＬ−２０−９９）５．２５質量部、塩化ビニル−酢酸ビニル共重合体（鐘淵化学工業社製；Ｍ２０１８、塩化ビニル８０質量％、酢酸ビニル２０質量％、平均重合度＝１８００）２８質量部、反応性ポリマー（新中村化学工業社製、ＮＫポリマーＢ−３０１５Ｈ）４．７質量部、ＴＨＦ２１５．５質量部、アミルアルコール２４質量部、及びジブチル錫ラウレート系安定剤（三共有機合成社製、Ｓｔａｎｎ　ＳＣＡＴ−１）０．８質量部からなる感熱層用塗布液を塗布し、加熱乾燥して約８μｍの厚みとなるように感熱層（可逆性感熱層）を設けた。次に、感熱層に対し、電子線照射装置として日新ハイボルテージ社製のエリアビーム型電子線照射装置ＥＢＣ−２００−ＡＡ２を用い、照射線量が１０Ｍｒａｄになるように調整して電子線照射を行い、比較例６の熱可逆記録媒体を作製した。
【０２０６】
（比較例７）
−熱可逆記録媒体の作製−
比較例１において、前記接着層上に、アクリル樹脂（ＬＲ−２６９、三菱レイヨン製）１００質量部、テトラエチレングリコールジアクリレート５０質量部、光重合開始剤（チバガイギー社製、イルガキュア１８４）２質量部、ポリエステル系可塑剤（ＤＩＣ社製、Ｐ−２９）２５質量部、ステアリン酸ステアリル４０質量部、エイコサンニ酸８質量部、及びテトラヒドロフラン１８０質量部からなる感熱層用塗布液を塗布し、１１０℃にて５分間加熱乾燥した後、１２０Ｗ／ｃｍ・１０ｍ／ｍｉｎの条件でＵＶ照射を行い、約１０μｍの厚みとなるように感熱層を設けた以外は、比較例１と同様にして、比較例７の熱可逆記録媒体を作製した。
【０２０７】
（実施例９）
−熱可逆記録ラベルの作製−
実施例４で作製した熱可逆記録媒体の支持体の感熱層面を設けてない側の面（裏面）に、約５μｍの厚みとなるようにアクリル系粘着剤層を設けた。
以上により、実施例１０の熱可逆記録ラベルを作製した。
【０２０８】
（実施例１０）
−熱可逆記録部材の作製及び評価−
実施例９で作製した熱可逆記録媒体の表面上にＵＶインク（ハクリＯＰニスＵＰ２　Ｔ＆ＫＴｏｋａ社製）による印刷を行い、これをカード状に切り出して記録及び消去手段（サーマルヘッド）とを有する記録装置を用いて、サーマルヘッドの記録エネルギーを熱可逆記録媒体の記録エネルギーの変化に合わせて調整して感熱層へ表示記録し、可視化し、記録及び消去を行った。更に、この表示記録の書き換えを５０回繰り返したが、記録及び消去は良好であった。
【０２０９】
（実施例１１）
−熱可逆記録部材の作製及び評価−
実施例９で作製した熱可逆記録ラベルをミニディスク（ＭＤ）カートリッジ上に貼り付けた。ＭＤに記憶された情報の一部（年月日、曲名など）を、記録及び消去手段（サーマルヘッド）とを有する記録装置を用いて、サーマルヘッドの記録エネルギーを媒体の記録エネルギーの変化に合わせて調整して感熱層へ表示記録し、可視化し、記録及び消去を行った。更に、この表示記録の書き換えを５０回繰り返したが、記録及び消去は良好であった。
【０２１０】
（実施例１２）
−熱可逆記録部材の作製及び評価−
実施例９で作製した熱可逆記録ラベルをＣＤ−ＲＷ上に貼り合わせて熱可逆表示機能付きの光情報記録媒体を作製した。この光情報記録媒体を用いて、ＣＤ−ＲＷドライブ（株式会社リコー社製、ＭＰ６２００Ｓ）で記憶した情報の一部（年月日、時刻など）を、記録及び消去手段（サーマルヘッド）を有する記録装置を用いて、サーマルヘッドの記録エネルギーを記録媒体の記録温度の変化に合わせて調整して感熱層へ表示記録し、可視化した。また、該ＣＤ−ＲＷドライブを用い、光情報記録媒体の記憶層の情報を書き換え、記録装置により消去手段を用い、先の記録を消去し新たにサーマルヘッドで、書き換えた情報を感熱層に書き換え、表示記録した。更に、この表示記録の書き換えを５０回繰り返したが、記録及び消去は良好であった。
【０２１１】
（実施例１３）
−熱可逆記録部材及び評価−
実施例９で作成した熱可逆記録ラベルをテープカセット上に貼り付けた。テープカセットに記憶された情報の一部（年月日、曲名など）を、記録及び消去手段（サーマルヘッド）を有する記録装置を用いて、サーマルヘッドの記録エネルギーをそれぞれの媒体の記録エネルギーの変化に合わせて調整して感熱層へ表示記録し、可視化し、記録及び消去を行った。更に、この表示記録の書き換えを５０回繰り返したが、記録及び消去は良好であった。
【０２１２】
次に、得られた実施例１〜９及び比較例１〜７の各熱可逆記録媒体について、以下のようにして、消去性、透明化温度幅、ガラス転移温度変化、耐アンモニア性、及び繰り返し耐久性について測定した。結果を表１及び表２に示す。
【０２１３】
＜消去性＞
感熱記録装置として八城電気社製印字試験装置を用い、サーマルヘッドとして京セラ（株）製ＫＢＥ−４０−８ＭＧＫ１を用いて、パルス幅２．０ｍｓｅｃ、印加電圧１１．０Ｖの条件で白濁画像形成を行った。その直後、サーマルヘッドによる印字条件をライン周期４．２ｍｓ、パルス幅２．９４ｍｓ、印字速度２９．７６ｍｍ／ｓに設定して印加エネルギーを０．０８５ｍｊ／ｄｏｔ〜０．３０ｍｊ／ｄｏｔまで適宜変更して透明化を行った。各々のエネルギーによる消去濃度をマクベスＲＤ−９１４濃度計（マクベス社製）にて測定し消去性を求めた。図４と同様にして消去濃度と消去エネルギーの関係をグラフにして消去可能エネルギー幅を求めた。また、最大に透明化した部位の濃度を最大透明濃度とし、その最大透明濃度と地肌との差を初期消去性とした。また、初期消去性と同一部位での濃度と地肌の差を経時消去性とした。実施例１〜６の結果を図１４〜図１９に示す。実施例７の結果を図２０に示す。比較例１〜６の結果を図２１〜図２６に示す。また、結果を表１に示す。
【０２１４】
＜透明化温度幅＞
前記透明化温度幅（ΔＴｗ）を、以下のようにして測定した。
予め、各熱可逆記録媒体を十分に白濁させた。次に、白濁した各熱可逆記録媒体について温度を変えて加熱し、透明になる温度を測定した。各熱可逆記録媒体の加熱には熱傾斜試験機（東洋精機社製ＨＧ−１００）を用いた。この熱傾斜試験機は５つの加熱ブロックを持ち、各ブロックは個別に温度を設定でき、加熱時間、圧力をコントロールすることも可能である。設定された条件で、一度に５つの異なる温度で熱可逆記録媒体を加熱することができる。具体的には、加熱時間を１．０秒とし、加熱時の圧力を約１．０ｋｇ／ｃｍ^２とする。加熱温度は、加熱しても白さが変化しない低温度から１〜５℃の等温度間隔で十分に白濁する温度まで加熱した。加熱した後、常温に冷却し、マクベスＲＤ−９１４反射濃度計（マクベス社製）を用い、各温度で加熱した部分の濃度を測定し、図３に示すように、横軸を熱傾斜試験機の設定温度、縦軸を反射濃度としたグラフを作成する。図３と同様にして透明化温度幅を求めた。実施例７の結果を図２７に示す。比較例１〜６の結果を図２８〜図３３に示す。また、結果を表１に示す。
【０２１５】
＜ガラス転移温度変化＞
示差熱層走査熱量として示差熱層走査熱量計６２００（ＳＩＩ社製）を用いてＤＳＣ測定を行った。各熱可逆記録媒体における感熱層の試料は、アルミニウム蒸着層上に塗布したものを希釈フッ化水素酸を用いて剥離し、その３ｍｇ〜６ｍｇをＤＳＣ測定用のアルミニウム製セルに入れて測定を行った。標準物質としては酸化アルミニウムを用いた。昇温速度は１５℃／ｍｉｎとした。
初期ガラス転移温度（Ｔｇｉ）は、ＤＳＣ測定用アルミニウム製セルに入れた試料を恒温槽中で１３０℃にて５分間加熱後に室温（２３℃）で３０分間放置した後に測定した。このときのＤＳＣ曲線から得られたガラス転移温度とし、経時ガラス転移温度は１３０℃にて５分間加熱後に室温で十分に冷却した後、３５℃雰囲気で１週間保存したものを測定した。このときのＤＳＣ曲線から得られたガラス転移温度を経時ガラス転移温度（Ｔｇａ）とした。
【０２１６】
＜耐アンモニア性＞
−透明化温度範囲試験−
実施例５及び７、並びに、比較例２及び５について、試験前の各熱可逆記録媒体の透明化温度範囲と、８質量％炭酸アンモニウム水溶液中に４８時間浸責した後の各熱可逆記録媒体の透明化温度範囲とを上記透明化温度範囲の測定方法により測定し、下記基準により評価した。
〔評価基準〕
○：変化なし
×：変化大
−画像濃度変化試験−
実施例５及び７について、塩基物質に浸漬していない各熱可逆記録媒体を白濁させたときの画像濃度を初期画像とし、熱可逆記録媒体を８質量％炭酸アンモニウム水溶液中に浸漬し、浸漬時間を１０分後、３０分後、１時間後、６時間後に変えて同じエネルギーで白濁させたときの画像濃度を測定した。
【０２１７】
＜繰り返し耐久性＞
実施例７及び８について、各熱可逆記録媒体について、サーマルヘッドを用いての繰返し耐久性を印字・消去を繰り返したときに画像濃度評価が０．５以上変化したときの回数を比較した。なお、最大５００回までの繰返し印字・消去の評価を行った。
【０２１８】
【表１】

【０２１９】
【表２】

【０２２０】
【発明の効果】
本発明によると、従来における問題を解決することができ、処理速度が速く、サーマルヘッドを用いてミリ秒単位の極小時間加熱した場合でも、十分に画像を消去することができ、画像形成経時後に、消去エネルギーが変化せず十分な消去性を維持し、高温で長時間放置しても保存性、コントラスト、視認性等に優れた画像を形成可能な熱可逆記録媒体、並びに、該熱可逆記録媒体を用いた、各種のラベル、カード等として好適な熱可逆記録ラベル、ディスク、ディスクカートリッジ、テープカセット等として好適な熱可逆記録部材、処理速度が速く、コントラスト、視認性等に優れた画像を形成可能な画像処理装置及び画像処理方法を提供することができる。
【図面の簡単な説明】
【図１】図１は、本発明の熱可逆記録媒体における温度と透明度変化との関係の一例を示すグラフである。
【図２】図２は、本発明の熱可逆記録媒体における温度と透明度変化との関係の一例を示すグラフである。
【図３】図３は、本発明の熱可逆記録媒体における、エネルギーの印加と消去エネルギー幅と反射濃度との関係の一例を示すグラフである。
【図４】図４は、ＤＳＣ測定によるエンタルピー緩和測定を示すグラフである。
【図５】図５は、本発明の熱可逆記録媒体ラベルをＭＤのディスクカートリッジ上に貼付した状態の一例を示す概略図である。
【図６】図６は、本発明の熱可逆記録ラベルをＣＤ−ＲＷ上に貼付した状態の一例を示す概略図である。
【図７】図７は、本発明の熱可逆記録ラベルを光情報記録媒体（ＣＤ−ＲＷ）上に貼付した状態の一例を示す概略断面図である。
【図８】図８は、本発明の熱可逆記録ラベルをビデオカセットに貼付した状態の一例を示す概略図である。
【図９】図９Ａは、支持体上に感熱層及び保護層を設けてなるフィルムを示す概略図。図９Ｂは、支持体上に反射層、感熱層及び保護層を設けてなるフィルムを示す概略図である。図９Ｃは、支持体上に反射層、感熱層及び保護層を設け、支持体の裏面に磁気感熱層を設けてなるフィルムを示す概略図である。
【図１０】図１０Ａは、本発明の熱可逆記録媒体の一例をカード状に加工したものの表面側の概略図である。図１０Ｂは、図１０Ａの裏面側の概略図である。
【図１１】図１１Ａは、本発明の熱可逆記録媒体の一例を他のカード状に加工した例の概略図である。図１１Ｂは、図１１ＡのＩＣチップ用窪み部に埋め込まれるＩＣチップの概略図である。
【図１２】図１２Ａは、集積回路を示す概略の構成ブロック図である。図１２Ｂは、ＲＡＭが複数の記憶領域を含むことを示す概略図である。
【図１３】図１３Ａは、面像の消去をセラミックヒータ、画像の形成をサーマルヘッドでそれぞれ行う場合の画像処理装置の概略図を示す。図１３Ｂは、本発明の画像処理装置の一例を示す概略図である。
【図１４】図１４は、実施例１における温度と透明度変化との関係を示すグラフである。
【図１５】図１５は、実施例２における温度と透明度変化との関係を示すグラフである。
【図１６】図１６は、実施例３における温度と透明度変化との関係を示すグラフである。
【図１７】図１７は、実施例４における温度と透明度変化との関係を示すグラフである。
【図１８】図１８は、実施例５における温度と透明度変化との関係を示すグラフである。
【図１９】図１９は、実施例６における温度と透明度変化との関係を示すグラフである。
【図２０】図２０は、実施例７における温度と透明度変化との関係を示すグラフである。
【図２１】図２１は、比較例１における温度と透明度変化との関係を示すグラフである。
【図２２】図２２は、比較例２における温度と透明度変化との関係を示すグラフである。
【図２３】図２３は、比較例３における温度と透明度変化との関係を示すグラフである。
【図２４】図２４は、比較例４における温度と透明度変化との関係を示すグラフである。
【図２５】図２５は、比較例５における温度と透明度変化との関係を示すグラフである。
【図２６】図２６は、比較例６における温度と透明度変化との関係を示すグラフである。
【図２７】図２７は、実施例７における反射濃度と温度との関係を示すグラフである。
【図２８】図２８は、比較例１における反射濃度と温度との関係を示すグラフである。
【図２９】図２９は、比較例２における反射濃度と温度との関係を示すグラフである。
【図３０】図３０は、比較例３における反射濃度と温度との関係を示すグラフである。
【図３１】図３１は、比較例４における反射濃度と温度との関係を示すグラフである。
【図３２】図３２は、比較例５における反射濃度と温度との関係を示すグラフである。
【図３３】図３３は、比較例６における反射濃度と温度との関係を示すグラフである。
【符号の説明】
１　　　熱可逆記録媒体
１０　　　熱可逆記録ラベル
１１　　　支持体
１２　　　アルミニウム反射層
１３　　　可逆性感熱層
１４　　　保護層
１６　　　磁気感熱層
２２　　　書き換え記録部
２３　　　印刷表示部
２４　　　磁気記録部
２５　　　窪み部
２６　　　書き換え記録部
３０　　　出入口
３１　　　搬送ローラ
３２　　　ガイドローラ
３３　　　センサ
３４　　　磁気ヘッド
３４ｃ　　制御手段
３５　　　プラテンローラ
３６　　　ガイドローラ
３７　　　搬送ローラ
３８　　　セラミックヒータ
３８ｃ　　セラミックヒータ制御手段
３９　　　ガイドローラ
４０　　　搬送ローラ
４３　　　センサ
４３ａ　　センサ
４４　　　プラテンローラ
４５　　　搬送ローラ
４６　　　搬送ローラ
４７　　　搬送ローラ
４８　　　搬送ベルト
４９ｂ　　搬送路
５０　　　搬送路
５１　　　センサ
５２　　　プラテンローラ
５３　　　サーマルヘッド
５３ｃ　　サーマルヘッド制御手段
５５ａ　　搬送路切換手段
５５ｂ　　搬送路切換手段
５６ａ　　搬送路
５６ｂ　　搬送路
５７ａ　　リミットスイッチ
５７ｂ　　リミットスイッチ
５８　　　搬送ベルト
５９　　　搬送ローラ
６０　　　ガイドローラ
６１　　　出口
７０　　　ＭＤディスクカートリッジ
７１　　　ＣＤ−ＲＷ
７２　　　ビデオカセット
１０１　　　保護層
１０２　　　可逆感熱層
１０３　　　光反射層
１０４　　　支持体
１０５　　　接着剤層又は粘着剤層
１０６　　　中間層
１０７　　　反射放熱層
１０８　　　第２誘電体層
１０９　　　光情報記憶層
１１０　　　第１誘電体層
１１１　　　基体
１１２　　　ハードコート層
２３１　　　ウエハ
２３２　　　ウエハ基板
２３３　　　集積回路
２３４　　　接触端子
２３５　　　ＣＰＵ
２３６　　　ＲＯＭ
２３７　　　ＲＡＭ
２３８　　　入出力インターフェース
２３９ａ〜２３９ｇ　記憶領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is suitable for applications such as a rewritable point card, a thermoreversible recording medium capable of quickly forming and erasing an image with excellent visibility, and a thermoreversible recording medium using the thermoreversible recording medium. The present invention relates to a reversible recording label, a thermoreversible recording member, an image processing device, and an image processing method.
[0002]
[Prior art]
The thermoreversible recording medium has a heat-sensitive layer in which the transparency changes reversibly depending on the temperature, and can easily form and erase an image at an arbitrary timing, so that it can be used as a rewritable point card or the like. In recent years, it has spread rapidly. Recently, as the thermoreversible recording medium, from the viewpoint of reducing the size and cost of the recording apparatus, it is possible to form and erase an image with only one thermal head without a special image erasing means. Therefore, the development of something that can be overwritten is desired.
[0003]
By the way, as those conventionally known as the thermoreversible recording media, for example, there are those in which an organic low-molecular compound such as a higher fatty acid is dispersed in a resin such as a vinyl chloride-vinyl acetate copolymer. (See Patent Document 1). However, in the case of the conventional thermoreversible recording medium, the temperature range width (hereinafter sometimes referred to as “transparency temperature range”) showing transparency (transparency) is as narrow as 2 to 4 ° C. There is a problem that it is not easy to control the temperature at the time of forming an image by utilizing light properties and opacity (light shielding properties). For this reason, it has been proposed to use a mixture of a higher fatty acid and an aliphatic dicarboxylic acid as the organic low molecular weight compound to widen the transparency temperature range to about 20 ° C. to erase an image (clear). (See Patent Documents 2 and 3). However, here, the opaque image can be erased (cleared) by heating for a relatively long time using a heat roller, a hot plate, or the like. However, when heating is performed for a minimum time of milliseconds using a thermal head, In addition, the temperature distribution increases in the thickness direction of the heat-sensitive layer, and the bottom of the heat-sensitive layer, which is far from the thermal head, is not sufficiently heated, so that the image cannot be sufficiently erased.
[0004]
Therefore, a thermoreversible recording medium capable of sufficiently erasing an image even when overwrite recording is performed using the thermal head has been proposed. For example, a thermoreversible recording medium containing a thioether and an aliphatic dibasic acid as the organic low-molecular compound has been proposed (see Patent Document 4). However, here, although the transparency temperature range when the thermoreversible recording medium is heated for a long time is widened, the image is still sufficiently erased when heating is performed for a minimum time of milliseconds using a thermal head. In addition, if the image is stored for a long time at a temperature higher than room temperature after the lapse of image formation, the erasing energy changes, making it difficult to erase the image, and there is a problem that sufficient erasability and contrast cannot be obtained.
Further, a method of containing an aliphatic thioether as an organic low molecular compound (see Patent Document 5) and a method of containing a higher fatty acid ester and an aliphatic dibasic acid as organic low molecular compounds (see Patent Document 6) are proposed. Have been. However, these methods use a resin with a glass transition temperature that is sufficiently higher than the crystallization temperature of the organic low-molecular-weight compound, so that heating with a thermal head for a minimum time of milliseconds causes the resin to soften sufficiently. Without erasing the image, it is difficult to erase the image if the image is stored for a long time at a temperature higher than room temperature after the lapse of image formation. There is no problem.
On the other hand, a method of containing a higher fatty acid hydrazide and an aliphatic saturated carboxylic acid as an organic low molecular compound (see Patent Document 7), and a method of containing a fatty acid ester and a fatty acid having a steroid skeleton as an organic low molecular compound (Patent Document 8) has been proposed. However, in these cases, the clearing temperature range is in the high temperature range and does not have a sufficient temperature range.Thus, when heating is performed for a minimum time of milliseconds using a thermal head, the image can be sufficiently erased. In addition, if the image is stored for a long time at a temperature higher than room temperature after image formation, the erasing energy changes and it becomes difficult to erase the image, and there is a problem that sufficient erasability and contrast cannot be obtained.
[0005]
On the other hand, it has been proposed to provide a temperature gradient relaxation layer on the surface of the heat-sensitive layer (see Patent Document 9). However, in this case, since the thickness of the heat-sensitive layer is large, when heating is performed for a minimum time of milliseconds using the thermal head, it is possible to sufficiently heat the bottom of the thermoreversible recording medium, that is, the side that does not contact the thermal head. It is not possible to perform image formation and erasure sufficiently, and if the image is stored at a temperature higher than room temperature for a long time after lapse of image formation, the erasing energy changes and the image becomes difficult to erase, and sufficient erasability and contrast are obtained. There is a problem that can not be obtained.
Further, a method of mixing a specific cross-linkable resin (see Patent Documents 10 to 11) and a method of containing a heat-sensitive polymer (see Patent Document 12) have been proposed. However, in these, although the erasability of the image is improved to some extent, if the image formation speed is heated for a very short time of milliseconds using a thermal head, sufficient erasability and contrast cannot be obtained. When stored at a temperature higher than room temperature for a long time after image formation, there is a problem that the erasing energy changes and sufficient erasability and contrast cannot be obtained.
[0006]
It has been proposed to use a resin having a glass transition temperature lower than the glass transition temperature of the resin base material in order to obtain a thermoreversible recording medium free from the above-mentioned problems (see Patent Document 13). However, in this case, there is a problem that the image retainability is not sufficient and the image disappears when stored at a temperature higher than room temperature after image formation, and a sufficient contrast cannot be obtained.
Further, it has been proposed to use a mixture of a chain isocyanate compound and a cyclic isocyanate compound as a cross-linking agent to reduce deterioration of the erasability of an image after image formation with time (see Patent Document 14). However, here, although the erasability of the image after image formation is improved by a static erasing method using a hot stamp or the like, the erasability of the image is reduced when heating is performed for a minimum time of milliseconds using a thermal head. There is a problem that the image cannot be sufficiently erased without improving.
Further, it has been proposed to mix a low-molecular-weight polyester resin having a freezing point of 30 ° C. or lower in a resin base material to lower the glass transition temperature (see Patent Documents 15 and 16). However, in these methods, there is a problem that the low-molecular-weight polyester resin migrates after the image is formed and the image disappears, a sufficient contrast cannot be obtained, and the low-molecular-weight polyester resin is precipitated.
[0007]
Therefore, even when heating is performed for a minimum time of milliseconds using a thermal head, an image can be sufficiently erased, and after lapse of image formation, sufficient erasability and contrast are maintained without changing the erasing energy, and At present, a thermoreversible recording medium capable of forming an image having excellent storage stability and visibility, and a related technique using the thermoreversible recording medium have not been provided yet.
[0008]
[Patent Document 1]
JP-A-55-154198
[Patent Document 2]
JP-A-2-1363
[Patent Document 3]
JP-A-3-2089
[Patent Document 4]
JP-A-11-115319
[Patent Document 5]
JP-A-2000-71623
[Patent Document 6]
JP-A-2000-71624
[Patent Document 7]
JP-A-7-101157
[Patent Document 8]
JP-A-8-282131
[Patent Document 9]
JP 2001-30633 A
[Patent Document 10]
JP-A-8-72416
[Patent Document 11]
JP-A-8-127183
[Patent Document 12]
JP-A-10-100457
[Patent Document 13]
Japanese Patent No. 3003745
[Patent Document 14]
JP 2000-198274 A
[Patent Document 15]
JP-A-2000-52662
[Patent Document 16]
JP-A-2002-113956
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention has a high processing speed and can sufficiently erase an image even when heating is performed for a minimum time of milliseconds using a thermal head. A thermoreversible recording medium capable of forming an image having excellent erasability, preservability even when left at high temperature for a long time, contrast, visibility, etc., and various labels using the thermoreversible recording medium, Thermoreversible recording label suitable as a card or the like, thermoreversible recording member suitable as a disc, disk cartridge, tape cassette, etc., an image processing apparatus and an image processing apparatus capable of forming an image with a high processing speed and excellent in contrast, visibility, etc. The aim is to provide a method.
[0010]
[Means for Solving the Problems]
The means for solving the above problems are as follows. That is,
<1> at least a heat-sensitive layer containing a resin and an organic low-molecular-weight compound, whose transparency reversibly changes depending on temperature, a glass transition temperature change in the heat-sensitive layer is −10 to 5 ° C., and A thermoreversible recording medium having a transparentization temperature range of 30 ° C. or more.
<2> at least a heat-sensitive layer containing a resin and an organic low-molecular-weight compound, whose transparency reversibly changes depending on temperature, wherein the resin contains an acrylic polyol resin, and a glass transition temperature change in the heat-sensitive layer Is -10 to 5 ° C.
<3> At least a heat-sensitive layer containing a resin and an organic low-molecular compound, the degree of transparency of which reversibly changes depending on the temperature, wherein the resin contains an acrylic resin, and the temperature range for clearing in the heat-sensitive layer is A thermoreversible recording medium characterized by being at least 40 ° C.
<4> At least a heat-sensitive layer containing a resin and an organic low-molecular-weight compound, whose transparency reversibly changes depending on temperature, wherein the resin contains an acrylic polyol resin, and a temperature range for clearing in the heat-sensitive layer Is 30 ° C. or higher.
<5> The thermoreversible recording medium according to any one of <1> to <4>, wherein the heat-sensitive layer has a glass transition temperature of 30 to 70 ° C.
<6> The thermoreversible recording medium according to any one of <1>, <3>, and <5>, wherein the resin contains an acrylic resin.
<7> The thermoreversible recording medium according to any one of <1> to <2> and <4> to <6>, wherein the resin contains an acrylic polyol resin.
<8> The thermoreversible recording medium according to any one of <1> to <7>, wherein the resin contains an acrylic polyol resin, and the acrylic polyol resin is crosslinked with an isocyanate compound.
<9> The thermoreversible recording medium according to <8>, wherein the amount of the isocyanate compound added is 1 to 50 parts by mass with respect to 100 parts by mass of the acrylic polyol resin.
<10> The thermoreversible recording medium according to any one of <2> and <4> to <9>, wherein the acrylic polyol resin has a glass transition temperature (Tg) determined from the following formula of 30 to 60 ° C. .
1 / Tg = Σ (Wi / Tgi)
In the above formula, Wi represents a mass fraction of the monomer i. Tgi represents the glass transition temperature (K) of the homopolymer of the monomer i.
<11> The thermoreversible recording medium according to any one of <2> and <4> to <10>, wherein the acrylic polyol resin has a hydroxyl value of 20 to 130 mgKOH / g.
<12> The thermoreversible recording medium according to any one of <2> and <4> to <11>, wherein the acrylic polyol resin has a refractive index of 1.45 to 1.60.
<13> The thermoreversible recording medium according to any one of <2> and <4> to <12>, wherein the acrylic polyol resin has a weight average molecular weight of 20,000 to 100,000.
<14> The thermoreversible recording medium according to any one of <1> to <13>, wherein the organic low-molecular compound is a compound containing no carboxyl group.
<15> The thermoreversible recording medium according to <14>, wherein the carboxyl group-free compound is any one selected from a fatty acid ester, a dibasic acid ester, and a polyhydric alcohol difatty acid ester.
<16> The thermoreversible recording medium according to any one of <1> to <15>, wherein an erasing energy width represented by the following formula when erasing an image immediately after image formation is 20 to 80%. .
Erasure energy width (%) = [(E ₂ -E ₁ ) / Ec] × 100
However, in the above formula, E ₁ Represents the lower limit (mj / dot) of the erasing energy, and E ₂ Represents the upper limit of the erasing energy (mj / dot), and Ec represents the erasing energy center value (E ₁ + E ₂ ) / 2 (mj / dot).
<17> When the image is erased after the lapse of image formation, the erasing energy width represented by the following formula is 20 to 80%, and the rate of change of the erasing energy width over time is 12% or less. To a thermoreversible recording medium according to any one of <16> to <16>.
Erasure energy width (%) = [(E ₂ -E ₁ ) / Ec] × 100
However, in the above formula, E ₁ Represents the lower limit (mj / dot) of the erasing energy, and E ₂ Represents the upper limit of the erasing energy (mj / dot), and Ec represents the erasing energy center value (E ₁ + E ₂ ) / 2 (mj / dot).
<18> The thermoreversible recording medium according to any one of <1> to <17>, having a support.
<19> The thermoreversible recording medium according to any one of <1> to <18>, further including one of an adhesive layer and a pressure-sensitive adhesive layer on a surface opposite to a surface on which an image is formed. This is a thermoreversible recording label.
<20> A thermoreversible recording member having an information storage unit and a reversible display unit, wherein the reversible display unit includes the thermoreversible recording medium according to any one of <1> to <18>. is there.
<21> A thermoreversible recording member including the thermoreversible recording medium according to <20>, wherein the information storage unit and the reversible display unit are integrated.
<22> The thermoreversible recording member according to any one of <20> to <21>, selected from a card, a disk, a disk cartridge, and a tape cassette.
<23> Image forming means for heating a thermoreversible recording medium to form an image on the thermoreversible recording medium, and image erasing for heating the thermoreversible recording medium to erase an image formed on the thermoreversible recording medium And a thermoreversible recording medium according to any one of <1> to <18>.
<24> The image processing apparatus according to <23>, wherein the image forming unit is a thermal head.
<25> The image processing apparatus according to any one of <23> to <24>, wherein the image erasing unit is one of a thermal head and a ceramic heater.
<26> At least the steps of heating the thermoreversible recording medium to form an image on the thermoreversible recording medium, and heating the thermoreversible recording medium and erasing the image formed on the thermoreversible recording medium An image processing method including any one of the above, wherein the thermoreversible recording medium is the thermoreversible recording medium according to any one of <1> to <18>.
<27> The image processing method according to <26>, wherein the image is formed using a thermal head.
<28> The image processing method according to any one of <26> to <27>, wherein the image is erased using one of a thermal head and a ceramic heater.
<29> The image processing method according to any one of <26> to <28>, wherein a new image is formed while erasing the image using a thermal head.
[0011]
The thermoreversible recording medium of the present invention comprises a resin and an organic low-molecular compound, and has at least a heat-sensitive layer whose transparency reversibly changes depending on temperature.In the first embodiment, the glass transition in the heat-sensitive layer The temperature change is −10 to 5 ° C., and the transparency temperature range is 30 ° C. or more. In the second embodiment, the resin contains an acrylic polyol resin, and the glass transition temperature change in the heat-sensitive layer is −10. To 5 ° C., in a third embodiment, the resin contains an acrylic resin, and the transparentization temperature range in the heat-sensitive layer is 40 ° C. or more, and in a fourth embodiment, the resin contains an acrylic polyol resin. And the transparentization temperature range in the heat-sensitive layer is 30 ° C. or more.
In the thermoreversible recording medium, when the resin is heated to a temperature higher than its softening temperature (Ts), the resin softens and voids formed at the interface between the resin and the organic low-molecular compound disappear. Is done. As a result, the image formed by the gap existing at the interface between the resin and the organic low-molecular compound is erased. When the heat-sensitive layer is cooled below the softening temperature (Ts) of the resin as it is, a state in which no void exists at the interface between the resin and the organic low-molecular compound is maintained, and the heat-sensitive layer maintains a transparent state. Then, the state where the image is erased is maintained. On the other hand, if the heat-sensitive layer is not cooled but is heated to a temperature higher than the melting point (Tm) of the organic low-molecular compound, the organic low-molecular compound melts in that portion. Thereafter, when the heat-sensitive layer is cooled to a temperature lower than the melting point (Tm) of the organic low-molecular compound and further lower than the softening temperature (Ts) of the resin, in that portion, the resin and the organic low-molecular compound are mixed. A void is formed at the interface, causing a cloudy state, and an image is formed.
In the thermoreversible recording media according to the first to fourth embodiments, at least two selected from the glass transition temperature change, the transparency temperature range, and the type of the resin are as described above, respectively. The image can be formed or erased by using a thermal head, and the image is sufficiently erased even when heated for a minimum time of milliseconds using a thermal head. Thus, an image excellent in storability, contrast, visibility and the like is formed even when left at a high temperature for a long time.
[0012]
The thermoreversible recording label of the present invention has one of an adhesive layer and a pressure-sensitive adhesive layer on the surface of the thermoreversible recording medium of the present invention opposite to the surface on which an image is formed. In the thermoreversible recording label, in the thermoreversible recording medium portion, the image is sufficiently erased even when heated for a minimum time of milliseconds using a thermal head, and the erasing energy does not change after the lapse of image formation. The erasability is maintained, and an image having excellent storability, contrast, visibility and the like is formed even when left at a high temperature for a long time. Further, since it has one of the adhesive layer and the pressure-sensitive adhesive layer, it can be applied to a wide range of applications such as a thick substrate such as a vinyl chloride card with a magnetic stripe, which is difficult to directly apply the heat-sensitive layer.
[0013]
The thermoreversible recording member of the present invention has an information storage section and a reversible display section, and the reversible display section is the thermoreversible recording medium of the present invention. In the thermoreversible recording member, a desired image is formed and erased at a desired timing in the reversible display section. At this time, even when heating is performed for a minimum time of milliseconds using a thermal head, the image is sufficiently erased, and the erasing energy does not change after the lapse of image formation. An image excellent in storability, contrast, visibility and the like is formed even when left unattended. On the other hand, in the information recording unit, desired information such as character information, image information, music information, and video information is recorded and erased by a recording method corresponding to the type of a card, a disk, a disk cartridge, a tape cassette, or the like. .
[0014]
The image processing apparatus of the present invention has at least one of an image forming unit for forming an image by heating the thermoreversible recording medium of the present invention and an image erasing unit for erasing the image. In the image processing apparatus, the image erasing unit heats the thermoreversible recording medium of the present invention. When the heat-sensitive layer in the thermoreversible recording medium is heated to a temperature equal to or higher than the softening temperature (Ts) of the resin, the resin softens in the heat-sensitive layer and is formed at the interface between the resin and the organic low-molecular compound. The formed voids disappear. As a result, the image formed by the gap existing at the interface between the resin and the organic low-molecular compound is erased. Then, as it is, the heat-sensitive layer is cooled to a temperature lower than the softening temperature (Ts) of the resin, a state in which no void exists at the interface between the resin and the organic low-molecular compound is maintained, and the heat-sensitive layer becomes a transparent state, The image is deleted. On the other hand, the image forming means heats the thermoreversible recording medium of the present invention. When the heat-sensitive layer in the thermoreversible recording medium is heated to a temperature equal to or higher than the softening temperature (Ts) of the resin, and further heated to a temperature equal to or higher than the melting point (Tm) of the organic low-molecular compound, the organic low-temperature compound The molecular compound melts. Thereafter, when the heat-sensitive layer is cooled to a temperature lower than the melting point (Tm) of the organic low-molecular compound and further lower than the softening temperature (Ts) of the resin, in that portion, the resin and the organic low-molecular compound are mixed. A void is formed at the interface, causing a cloudy state, and an image is formed.
[0015]
The image processing method of the present invention heats the thermoreversible recording medium of the present invention to form an image and / or erase an image. In the image processing method, when the thermoreversible recording medium of the present invention is heated, and the thermosensitive layer in the thermoreversible recording medium is heated to a temperature equal to or higher than the softening temperature (Ts) of the resin, the thermosensitive layer: The resin softens, and the voids formed at the interface between the resin and the organic low-molecular compound disappear. As a result, the image formed by the gap existing at the interface between the resin and the organic low-molecular compound is erased. Then, as it is, the heat-sensitive layer is cooled to a temperature lower than the softening temperature (Ts) of the resin, a state in which no void exists at the interface between the resin and the organic low-molecular compound is maintained, and the heat-sensitive layer becomes a transparent state, The image is deleted. On the other hand, the thermoreversible recording medium of the present invention is heated, the thermosensitive layer in the thermoreversible recording medium is heated to a temperature equal to or higher than the softening temperature (Ts) of the resin, and further equal to or higher than the melting point (Tm) of the organic low molecular compound. When the organic low-molecular-weight compound is heated, the organic low-molecular-weight compound melts in that portion. Thereafter, when the heat-sensitive layer is cooled to a temperature lower than the melting point (Tm) of the organic low-molecular compound and further lower than the softening temperature (Ts) of the resin, in that portion, the resin and the organic low-molecular compound are mixed. A void is formed at the interface, causing a cloudy state, and an image is formed.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Thermo-reversible recording medium)
The thermoreversible recording medium of the present invention contains at least a resin and an organic low-molecular compound, further contains other components appropriately selected as necessary, and at least a heat-sensitive layer whose transparency reversibly changes depending on temperature. Preferably, it has any one of the following first to fourth modes.
In the first embodiment, the glass transition temperature change in the heat-sensitive layer is -10 to 5C, and the transparency temperature range is 30C or more. In the second embodiment, the resin contains an acrylic polyol resin, and the heat-sensitive layer has a glass transition temperature change of -10 to 5C. In the third embodiment, the resin contains an acrylic resin, and a transparentization temperature range in the heat-sensitive layer is 40 ° C. or more. In the fourth embodiment, the resin contains an acrylic polyol resin, and a transparentization temperature range in the heat-sensitive layer is 30 ° C. or more.
[0017]
The transparency of the heat-sensitive layer reversibly changes from a transparent state to a cloudy state (hereinafter sometimes referred to as an “opaque state”) depending on the temperature. In the thermoreversible recording medium of the present invention, an image is formed and erased by utilizing the change in transparency in the heat-sensitive layer. The mechanism by which the transparency changes in the heat-sensitive layer is presumed, for example, as follows. That is, in the heat-sensitive layer, the organic low-molecular compound is dispersed in the resin (sometimes referred to as a “resin base material” or a “matrix resin”) in a particle form. When the heat-sensitive layer is in the “transparent state”, there is no void at the interface between the organic low-molecular compound dispersed in the resin and the resin and the resin, and light incident on the heat-sensitive layer is scattered. Without penetrating. As a result, the heat-sensitive layer becomes “transparent”. On the other hand, when the heat-sensitive layer is in the `` white turbid state '', a void exists at the interface between the organic low-molecular compound dispersed in the resin and the resin, and light incident on the heat-sensitive layer is It is largely refracted and scattered at the interface between the void and the low-molecular organic compound and at the interface between the void and the resin. As a result, the heat-sensitive layer becomes "white turbid". In other words, only the portion where the void exists is "opaque", and the other portions are "transparent", and a desired image is formed by the contrast between the opacity and the transparency. The “image” formed here includes characters, symbols, figures, pictures, images, any combination thereof, and the like.
[0018]
Here, formation and deletion of an image on the thermoreversible recording medium will be described with reference to the drawings. FIG. 1 is a graph showing an example of a change in transparency depending on a heating temperature of a thermosensitive layer in a thermoreversible recording medium. This graph is an example of the case where the resin is polyester or the like and the organic low molecular weight compound is a higher alcohol, a higher fatty acid or the like, but the material such as the resin or the organic low molecular weight compound is changed. May be slightly deformed.
[0019]
In FIG. 1, the heat-sensitive layer containing the resin and the organic low-molecular compound dispersed in the resin has a temperature of “T ₀ At normal temperature below, it is assumed to be in a "white turbid" state (opaque). As the heat-sensitive layer is heated, the temperature “T ₁ ”And gradually begin to become transparent, and the temperature“ T ₂ "~" T ₃ ”, The thermosensitive layer becomes“ transparent ”. From this “transparent” state, ₀ The temperature-sensitive layer is maintained in the "transparent" state even when the temperature is returned to the normal temperature below. That is, the temperature “T ₁ ), The resin starts to soften, and as the temperature rises, the resin and the organic low molecular weight compound expand together, but the organic low molecular weight compound has a larger degree of expansion than the resin, The low molecular compound gradually reduces the voids at the interface with the resin, resulting in a gradual increase in transparency. Temperature "T ₂ "~" T ₃ In the above, the organic low-molecular compound is in a semi-molten state, and the remaining voids are filled with the semi-molten organic low-molecular compound to be in a “transparent” state. When the heat-sensitive layer is cooled in this state, the organic low-molecular compound crystallizes at a relatively high temperature and changes in volume. At this time, since the resin is in a softened state, it is possible to follow a change in volume due to crystallization of the organic low-molecular compound, and no void is generated at the interface between the organic low-molecular compound and the resin, and thus “transparent” The state is maintained.
Further, the heat-sensitive layer is heated at a temperature “T ₄ Above, the thermosensitive layer will be in a "translucent" state intermediate between maximum transparency and maximum opacity. Next, when the temperature is lowered, the state becomes "opaque" (opaque) without becoming "transparent". That is, when the organic low-molecular-weight compound has a temperature “T ₄ After completely melting at the temperature above “T ₀ Crystallizes at slightly higher temperatures. At this time, the resin cannot follow the volume change due to the crystallization of the organic low-molecular compound, and a void is formed at the interface between the organic low-molecular compound and the resin, so that the resin becomes “white turbid”.
[0020]
As described above, the formation and erasure of an image on the thermoreversible recording medium are performed by utilizing the change in transparency of the heat-sensitive layer from a “transparent” state to a “white turbid” state. In the heat-sensitive layer, the change in the transparency from the “transparent” state to the “white turbidity” state includes the glass transition temperature (Tg), the degree of change of the glass transition temperature with time (ΔTg), the transparency temperature width (ΔTw), The initial erasing energy width, the rate of change of the erasing energy width with time, the softening point temperature of the resin or the organic low-molecular compound in the thermosensitive layer, and the deformation behavior at or above the softening point temperature are important.
[0021]
-Glass transition temperature (Tg)-
The glass transition temperature (Tg) of the heat-sensitive layer is not particularly limited and may be appropriately selected depending on the purpose. For example, 30 to 70 ° C is preferable, and 30 to 50 ° C is more preferable.
If the glass transition temperature (Tg) is less than 30 ° C., it may not be possible to sufficiently cloud at room temperature (hereinafter, 23 ± 3 ° C .; the same applies hereinafter). The repetition durability of the heat-sensitive layer may decrease.
[0022]
The glass transition temperature of the heat-sensitive layer is obtained from a curve (DSC) of a transition portion observed at the time of temperature rise, which is measured according to JIS K7121 (established in 1987, 1999 version). The transition temperature is the temperature at the intersection with the curve of the stepwise change portion. This is because the temperature at the intersection of a straight line that extends the low-temperature baseline to the high-temperature side and a tangent drawn at a point where the slope of the curve of the step change portion of the glass transition temperature becomes the maximum is defined as the "correction glass transition temperature". The temperature at the intersection of a straight line obtained by extending the base line on the high-temperature side to the low-temperature side and a tangent drawn at the point where the gradient becomes the maximum on the curve on the high-temperature side of the peak is referred to as “correction glass”. When "transition end temperature (Teg)" is set, it is equal to the midpoint between "Tig" and "Teg" in the vertical direction. When a peak appears on the high temperature side of the step change, the “corrected glass transition end temperature (Teg)” for obtaining the glass transition temperature is determined by using a straight line obtained by extending the high temperature side base line to the low temperature side and a high temperature of the peak. The temperature at the intersection of the tangent drawn at the point where the gradient of the tangent drawn at the point where the slope of the side curve has the maximum is the maximum.
[0023]
Specifically, the glass transition temperature of the heat-sensitive layer can be measured using, for example, a DSC measurement device. That is, first, the heat-sensitive layer in the thermoreversible recording medium is peeled off. At this time, as long as the glass transition temperature of the heat-sensitive layer can be measured, a small amount of a protective layer or an adhesive layer may be attached to the heat-sensitive layer. In addition, as a method of peeling the heat-sensitive layer, for example, when the heat-sensitive layer is applied on the aluminum vapor-deposited layer, remove the portion of the layer applied on the heat-sensitive layer such as a protective layer with sandpaper or the like. By dissolving the aluminum deposition portion with hydrochloric acid, hydrofluoric acid, or the like, a film-like heat-sensitive layer can be obtained. Next, the peeled heat-sensitive layer is placed in a DSC measurement cell made of aluminum or the like and subjected to measurement.
The DSC measurement device is not particularly limited and can be appropriately selected from known devices depending on the purpose. For example, a differential thermal layer scanning calorimeter 6200 manufactured by SII is preferably used. In the DSC measurement device, the amount of the sample is generally about 5 mg, the standard substance is aluminum oxide or the like, and the heating rate is about 15 ° C./min. If the amount of the sample is too small, the data has a large amount of noise, and if the amount is too large, it is difficult to transfer heat to the entire sample, and in any case, it is difficult to obtain accurate data.
[0024]
-Temporal change of glass transition temperature ([Delta] Tg)-
The time-dependent change (ΔTg) of the glass transition temperature of the heat-sensitive layer is required to be −10 to 5 ° C. in the first embodiment and the second embodiment, and −7 to 5 ° C. is more preferable. Preferably, in the third embodiment and the fourth embodiment, -10 to 5C is preferable, and -7 to 5C is more preferable.
When the time-dependent change (ΔTg) of the glass transition temperature is within the above-mentioned numerical range, the shift of the glass transition temperature of the heat-sensitive layer to the high temperature side after the lapse of image formation is reduced, and the erasability is maintained even after the lapse of image formation. Is good.
The degree of change of the glass transition temperature with time (ΔTg) means the glass transition temperature (Tga) after image formation lapse of time minus the glass transition temperature (Tgi) immediately after image formation (initial stage). Here, the “glass transition temperature (Tga) after image formation aging” refers to a temperature lower by 5 ° C. than the glass transition temperature (Tg) in the heat-sensitive layer (for example, 35 ° C. if the Tgi is 40 ° C.). ) Means the glass transition temperature measured after storage for one week.
[0025]
The temporal change (ΔTg) of the glass transition temperature can be measured, for example, as follows. That is, first, the sample of the thermosensitive layer is heated in a thermostat at 130 ° C., which is sufficiently higher than the softening temperature of the thermosensitive layer, for 5 minutes in a state where the sample of the thermosensitive layer is placed in the cell for DSC measurement. Soften. Next, the DSC measurement cell containing the softened sample of the heat-sensitive layer was taken out of the thermostat, allowed to cool at room temperature for 2 hours, and the resin in the heat-sensitive layer was changed to a glass state, and the measurement was performed by the above method. The glass transition temperature was defined as "glass transition temperature (Tgi) immediately after (initial) image formation".
[0026]
Immediately after the sample of the heat-sensitive layer is softened, the resin of the heat-sensitive layer is not sufficiently cooled, and the glass transition temperature cannot be accurately measured. As a result, accurate DSC measurement data of “glass transition temperature (Tgi) immediately after (initial) image formation” can be obtained. If the "glass transition temperature (Tgi) immediately after (initial) image formation" cannot be obtained even after leaving at room temperature for 30 minutes, the standing time is further extended to about 3 hours to leave the heat-sensitive layer. The resin takes a stable glass state, and the "glass transition temperature (Tgi) immediately after (initial) image formation" can be measured.
If the leaving time is too short, it may be difficult to accurately measure the “glass transition temperature (Tgi) immediately after (initial) image formation”. If the leaving time is too long, the “enthalpy relaxation” phenomenon occurs, and “ The glass transition temperature (Tgi) immediately after (initial) image formation may shift to a high temperature, and thus the leaving time is preferably about 30 minutes to 3 hours.
On the other hand, after the heating, the sample of the heat-sensitive layer is sufficiently cooled at room temperature (23 ° C.), and thereafter, at a temperature lower by 5 ° C. than the glass transition temperature (Tg) of the heat-sensitive layer (for example, in the above “immediately after image formation (initial)”). The glass transition temperature measured after storage for one week at a glass transition temperature (Tgi) of 40 ° C. (35 ° C.) is referred to as “glass transition temperature (Tga) after image formation lapse of time”.
[0027]
-Transparency temperature range (ΔTw)-
The transparency temperature range (ΔTw) is not particularly limited and can be appropriately selected depending on the intended purpose. For example, in the first embodiment and the third embodiment using an acrylic polyol resin as the resin, It is necessary to be 30 ° C. or higher, preferably 40 ° C. or higher, and when the upper limit is also specified, 30 to 90 ° C. is preferable, 40 to 90 ° C. is more preferable, 40 to 80 ° C. is particularly preferable, and the second In the embodiment, the temperature is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and when the upper limit is also defined, 30 to 90 ° C. is preferable, 40 to 90 ° C. is more preferable, and 40 to 80 ° C. is particularly preferable. In the fourth embodiment using a resin, the temperature needs to be 40 ° C. or higher, and if the upper limit is also specified, it is preferably 40 to 90 ° C., and more preferably 40 to 80 ° C.
The wider the transparentization temperature range (ΔTw), the better the erasability or high-speed erasability, and even when the thermal layer is heated for a short time by the thermal head, the heat-sensitive layer softens the resin or the organic low-molecular compound. Temperature, the erasing speed is high, and uniform erasing can be performed. On the other hand, when the temperature is lower than 30 ° C., the erasing property is reduced, and the erasing property by the thermal head may be insufficient. If the temperature exceeds 90 ° C., the clouding temperature becomes too high, so that a large amount of energy must be applied when forming a cloudy image, thereby shortening the life of the thermal head or reducing the durability of the thermoreversible recording medium. Sometimes.
[0028]
The clearing temperature range (ΔTw) is defined as follows. First, as shown in FIG. ₁ ~ T ₃ T after heating ₀ Upon cooling to the following temperatures, the transparency of the thermoreversible recording medium changes between a "white turbid" state and a "transparent" state. In FIG. 2, the transparency value (density) t in the maximum “cloudy” state ₁₁ , The transparency value (density) t in the maximum "transparent" state ₁₂ And the transparency value t in the maximum "cloudy" state ₁₁ The transparency value (density) obtained by adding the transparency value (density) corresponding to 80% of the difference from ₁₃ And This transparency value (density) t ₁₃ The temperature at which the above transparency is obtained is referred to as “transparency temperature”, and the range is referred to as “transparency temperature range (T ₄ ~ T ₅ )] And the width is referred to as “transparency temperature width (ΔTw = Tw ₅ -T ₄ ) ". At this time, when the transparency value (density) in the maximum “transparent” state is the non-image forming portion, that is, the transparency value (density) of the transparent portion not heated is “background density”, Transparency value (density) t in the state ₁₂ If the background density is higher than the background density, the “background density” is set to the transparency value (density) t. ₁₂ It is said.
[0029]
The clearing temperature range (ΔTw) can be measured, for example, as follows. That is, first, the thermoreversible recording medium that is not sufficiently opaque or is in a transparent state is made opaque by pressing it against a sufficiently heated hot plate or by heating in a thermostat. At this time, the heating time may be, for example, about 10 to 30 seconds when using the hot plate, or about 1 to 5 minutes when using the constant temperature bath. In addition, in order to confirm that the heating temperature is a sufficient temperature for clouding the thermoreversible recording medium, heating is performed again at a temperature slightly higher than the temperature (for example, a temperature higher by 10 ° C.), If the cloudiness density does not change before and after the reheating, it means that the heating temperature before the reheating was a sufficient temperature for the clouding. On the other hand, if the cloudiness density changes before and after the reheating, and if the cloudiness density after the reheating is higher than before the heating, the temperature is still low at the temperature before the reheating, and the cloudiness is reduced. Temperature was not enough for In this case, the heating temperature may be increased and heating may be repeated again.
Next, the thermoreversible recording medium in the cloudy state was heated while changing the temperature, and the temperature at which the thermoreversible recording medium became transparent was examined. For the heating of the thermoreversible recording medium, for example, a heat gradient tester (HG-100, manufactured by Toyo Seiki Co., Ltd.) having five heating blocks and setting and controlling the heating time, pressure, temperature, etc. for each block can be controlled. Can be suitably used. In this case, the heating time is 1.0 second, and the pressure is about 1.0 kg / cm. ² The temperature ranges from a low temperature at which the “white turbidity” state does not change even when heated, to a temperature sufficient for the white turbidity at an isothermal interval of 1 to 5 ° C. In order to prevent the thermoreversible recording medium from sticking to each heating block, the thermoreversible recording medium may be disposed on a thin (10 μm or less) film of polyimide or polyamide.
After heating as described above, the temperature was cooled to room temperature, and the density in the thermoreversible recording medium heated in each heating block was measured using a Macbeth RD-914 reflection densitometer (manufactured by Macbeth). Then, as shown in FIG. 2, the horizontal axis represents the heating temperature (the set temperature of the thermal gradient tester), and the vertical axis represents the reflection density (the reflection density in the thermoreversible recording medium). A graph is created by plotting the values and connecting adjacent points of the plot with straight lines. At this time, when a transparent support is used as the thermoreversible recording medium, the density is measured by laying a light absorbing sheet or a light reflecting sheet on the back surface of the thermoreversible recording medium.
As shown in FIG. 2, the graph usually has a substantially trapezoidal shape. In FIG. 2, "T ₀ Means the temperature at which the cloudiness density does not change even if the cloudy image is heated at that temperature and then cooled. "T ₁ "Represents the lowest temperature at which the cloudiness density changes when cooled at that temperature. "T ₂ "Represents the temperature at which the transparency value is at its maximum" transparent "state when heated after cooling at that temperature. "T ₃ "Represents the temperature at which the transparency value is at its maximum" white turbidity "when heated at that temperature and then cooled.
[0030]
−Initial erase energy width−
The initial erasing energy width is not particularly limited and may be appropriately selected depending on the intended purpose; however, a wider one generally has better erasability, for example, preferably 20 to 80%, and more preferably 30 to 75%. , 40 to 60% is particularly preferred.
If the initial erasing energy width is less than 20%, erasing may not be sufficiently performed in the case of short-time heating with a thermal head or the like, and if it exceeds 80%, the lower limit of the initial erasing energy width may be reduced. Value, the image heat resistance during high-temperature storage deteriorates, the upper limit of the initial erasing energy increases, and high energy must be applied to make the cloudy state, and image formation and erasure are repeated. Of the thermal head may be shortened, and the life of the thermal head may be shortened.
[0031]
The initial erasing energy width means a width of energy capable of erasing the cloudy image with a thermal head immediately after forming the cloudy image on the heat-sensitive recording material, and is defined as follows. That is, in FIG. 3, the transparency value (density) t in the maximum “white turbid” state ₁₁ , The transparency value (density) t in the maximum "transparent" state ₁₂ And the transparency value (density) t in the maximum "white turbid" state ₁₁ The transparency value (density) obtained by adding the transparency value (density) corresponding to 80% of the difference from ₁₃ And This transparency value (density) t ₁₃ The energy at which the above transparency is obtained is referred to as “initial erasing energy”, and the range is referred to as “erasing energy range (E ₁ ~ E ₂ ) ". The initial erasing energy range (E ₁ ~ E ₂ ), The lower limit value E of the erasing energy ₁ And upper limit E ₂ Is set as the initial erasing energy center value Ec. In addition, the initial erasing energy range (E ₁ ~ E ₂ ), The lower limit value E of the erasing energy in the initial erasing energy range with respect to the initial erasing energy center value (Ec). ₁ And upper limit E ₂ Difference (E ₂ -E ₁ ) Is calculated, and this is defined as the “initial erase energy width”.
Therefore, the initial erase energy width is represented by the following equation.
Initial erase energy width (%) = [(E ₂ -E ₁ ) / Ec] × 100
In the above formula, E ₁ Represents the lower limit (mj / dot) of the erasing energy in the initial erasing energy range, and E ₂ Represents the upper limit (mj / dot) of the erasing energy in the initial erasing energy range, and Ec represents the initial erasing energy center value (E ₁ + E ₂ ) / 2 (mj / dot).
[0032]
Here, the reason why the initial erasing energy width (%) is defined by the ratio to the initial erasing energy center value is as follows. That is, when the initial erasing energy width is in a low energy range, in erasing an image by heating using a thermal head, the thermoreversible recording medium is hardly affected by an environmental temperature change, and its surface and It is difficult to accumulate thermal energy from the thermal head because the temperature distribution between the thermal reversible recording medium and the rear surface is small. (The thermal diffusion of the thermoreversible recording medium in the horizontal plane direction does not affect adjacent dot areas in the thermoreversible recording medium. ). On the other hand, when the initial erasing energy width is in a high energy range, the thermoreversible recording medium is susceptible to an environmental temperature change, and has a large temperature distribution between the front surface and the back surface. Easily accumulates thermal energy from As described above, since the initial erasing energy width is easily affected by the energy range in which the initial erasing energy width is present, the initial erasing energy width is expressed as a ratio to the center value of the energy in order to reduce the influence. It is effective.
[0033]
The initial erasing energy width can be measured, for example, as follows. That is, first, the thermoreversible recording medium cooled to room temperature is heated at an arbitrary energy value by a thermal head (manufactured by Kyocera, KBE-40 head) using a printing tester (manufactured by Become Inc.). To delete.
The thermoreversible recording medium from which the image was erased was cooled to room temperature after heating, and the density of the thermoreversible recording medium was measured using a Macbeth RD-914 reflection densitometer (manufactured by Macbeth). Then, as shown in FIG. 3, the abscissa is the erasing energy (mj / dot), the ordinate is the reflection density (reflection density in the thermoreversible recording medium), and the density value for each erasing energy is plotted. A graph is created by connecting adjacent points of the plot with straight lines.
[0034]
As the measurement conditions of the initial erasing energy width, first, the printing conditions of the thermal head of the printing test apparatus are, for example, a pulse width of 2.94 msec, a line cycle of 4.2 msec, a printing speed of 30 mm / sec, and a platen roll pressure of 2 kg / cm. ² Set to. Next, the thermoreversible recording medium in the “transparent” state is heated at an arbitrary energy value, then cooled to room temperature, and the energy value at which the cloudy saturation concentration is obtained.
[0035]
As conditions for erasing and forming an image formed on the thermoreversible recording medium, the pulse width, the line cycle, and the printing speed are important conditions. Is preferably, for example, 19 to 60 mm / sec, more preferably 25 to 35 mm / sec, and the line cycle is, for example, 2.0 to 6.6 msec, preferably 3.5 to 4.5 msec. More preferably, the pulse width is, for example, preferably 2.0 to 5.0 msec, and more preferably 2.5 to 3.5 msec.
The thermal head is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a head other than the end face head may be used, but the main scanning line density of the thermal head is 8 dots / dot. mm is preferred. The upper limit energy value of the erasing energy range of the thermoreversible recording medium by the thermal head is preferably 0.8 mJ / dot or less. In this case, since high energy is not applied to the thermoreversible recording medium, image deterioration due to repetition of image formation and erasing can be suppressed, and the life of the thermal head in the printing apparatus is reduced. Can be suppressed. The wider the erasing energy range, the better the erasability of the image by the thermal head.
[0036]
In order to widen the initial erasing energy width, the heat-sensitive layer softens rapidly near the softening point temperature and has excellent thermal responsiveness and is high at room temperature even when heated for a short time by a thermal head or the like. Resins having viscoelasticity are preferred. This is advantageous in that a high contrast is obtained in the thermoreversible recording medium.
Methods for obtaining such a resin include, for example, the following two methods.
One is a method of incorporating a steric hindrance structure into the side chain of the resin. Examples of the structure acting as a steric hindrance include a linear alkyl group and a branched alkyl group. The number of carbon atoms of the linear alkyl group is, for example, preferably 2 to 20, more preferably 2 to 10, and particularly preferably 5 to 10. Specific examples of the straight-chain alkyl group include a butyl group and an ethylhexyl group.
The other is a method using a material capable of imparting flexibility to the resin. Examples of the material capable of imparting flexibility include a method using a crosslinking agent having a flexible structure, a method using a plasticizer, and the like. Examples of the crosslinking agent include a crosslinking agent having a chain isocyanate group. Examples of the plasticizer include a phthalic acid-based plasticizer.
When the resin obtained by these methods is used, the energy required for softening the heat-sensitive layer can be reduced, and the initial erasing energy width can be widened. Further, even after long-term storage, the polymer chains are less likely to aggregate and the above-mentioned "enthalpy relaxation" phenomenon is less likely to occur, so that the rate of change of the glass transition temperature after image formation time is reduced. On the other hand, when a resin in which the “enthalpy relaxation” phenomenon easily occurs is used for the heat-sensitive layer, the erasing energy shifts to a higher energy side after long-term storage, the erasing energy width over time becomes narrower, and the erasing cannot be performed sufficiently. Sometimes.
[0037]
−Erase energy width over time−
The temporal erasing energy width is not particularly limited and may be appropriately selected depending on the purpose. However, a wider erasing energy generally has better erasability, and for example, preferably 20 to 80%, and more preferably 30 to 75%. , 40 to 60% is particularly preferred.
If the erasing energy width over time is less than 20%, erasing may not be sufficiently performed in the case of short-time heating with a thermal head or the like. The lower the value, the lower the image heat resistance during high-temperature storage, the higher the upper limit of the erasing energy over time, and a higher energy must be applied to make the cloudy state. Of the thermal head may be shortened, and the life of the thermal head may be shortened. The temporal erasure energy width means the width of the energy capable of erasing the cloudy image with a thermal head after forming a cloudy image on the heat-sensitive recording material and then storing it at a high temperature for a long period of time. It is defined similarly and can be measured similarly.
[0038]
-Rate of change over time of erase energy width-
The rate of change of the erasing energy width with time is not particularly limited and can be appropriately selected depending on the purpose. For example, 12% or less is preferable, 10% or less is more preferable, and 7% or less is particularly preferable.
When the rate of change of the erasing energy width over time is 12% or less, the erasing energy width over time is stable, and even after aging, the same reflection density as when an image is erased with the initial erasing energy value is obtained. When the image is formed and erased by the same printing device after storage over time, the contrast is stable. On the other hand, when it exceeds 12%, the image is erased using the same thermal head and the like with the same erasing energy. In some cases, the image cannot be sufficiently erased even if the image is erased.
The reason is as follows. That is, as shown in FIG. 4, in the resin (polymer compound), a baseline change and a peak near the glass transition temperature are generally observed when the temperature is increased by DSC measurement. The peak is small immediately after the resin (polymer compound) is rapidly cooled after heating. However, after the resin (polymer compound) is stored at a temperature lower than the glass transition temperature after heating, a large endothermic peak is generated on the low temperature side of the glass transition temperature (see “Resin which changes greatly with time” in FIG. 4). The peak area of the endothermic peak increases with the extension of the storage time. Further, the glass transition temperature of the resin (polymer compound) shifts to a higher temperature side with the extension of the storage time. Looking at this phenomenon with respect to the thermoreversible recording medium, when an image (opaque image) is formed and left (stored) in a high-temperature environment for a long period of time after that, it is heated by a thermal head for a short time of the order of several msec. When an image formed on a thermoreversible recording medium is erased, the transparent reflection density and contrast generally decrease due to the fluctuation of the erasing energy width over time. This change in the erasing energy width over time is different from the initial erasing energy width when the image is erased by the thermal head immediately after the image formation, after the image formation lapse (after the image formation, the thermoreversible recording medium is exposed to a high temperature environment. (When left for a long time), the temporal erasing energy width is caused by narrowing. In the temporal erasing energy width, generally, no shift of the upper limit of the temporal erasing energy range is observed on the high energy side, On the low energy side, the lower limit of the temporal erasing energy range is large and shifts to the high energy side.
On the other hand, among resins, even after storage at a temperature lower than the glass transition temperature after heating, the phenomenon that the peak area does not increase or the glass transition temperature does not shift to a high temperature side is hardly observed (see FIG. 4, "Resin with little change over time"). Since the "enthalpy relaxation" phenomenon of the resin does not occur in the thermosensitive layer using the resin, the rate of change of the erasing energy width over time does not change to more than 12%, and the erasure of an image on the thermoreversible recording medium is prevented. This is advantageous in that the properties are not changed by long-term storage, and the erasability of the image is excellent.
[0039]
The rate of change with time of the erasing energy width means the rate of change with time of the energy width at which an image can be erased by heating with a thermal head. The smaller this value is, the smaller the initial erasing energy that can be erased immediately after image formation. This means that the change in the erasure energy width over time, which can be erased after aging after storage at a temperature equal to or lower than the softening point temperature of the thermosensitive layer after image formation, is small.
The rate of change of the erasing energy width with time can be obtained as follows. That is, first, an image (opaque image) is formed on the heat-sensitive layer by the thermal head, the erasing energy width after leaving at 35 ° C. for one week is calculated in the same manner as the initial energy width, and the value is referred to as “erasing with time”. Energy width E _D ". Next, the “initial erasing energy width E” immediately after the image was formed. _l And the "time-dependent change rate (%) of the erase energy width" can be calculated from the following equation.
Time-dependent change rate (%) of erasing energy width = [(E _I -E _D ) / E _I ] X 100
In the above formula, E _I Represents the initial energy width (mj / dot), and E _D Represents the energy width over time (mj / dot).
[0040]
In order to make the rate of change of the erasing energy width over time to 12% or less, it is preferable that physical properties do not change between the thermosensitive layer after image formation and the thermosensitive layer immediately after image formation, It is preferable to use a resin that does not cause the “enthalpy relaxation” phenomenon of the above-mentioned resin as the resin constituting the heat-sensitive layer.
[0041]
-Resin-
The resin is not particularly limited and can be appropriately selected depending on the intended purpose. For example, in the first embodiment, the resin preferably includes an acrylic resin, and among the acrylic resins, an acrylic polyol resin It is particularly preferable to include, in the third embodiment, the resin needs to include an acrylic resin, it is particularly preferable to include an acrylic polyol resin, and in the second embodiment and the fourth embodiment, It is necessary that the resin comprises an acrylic polyol resin.
In the case of the first embodiment and the third embodiment, the acrylic resin has a quick drying property at the time of film formation, easily forms a heat-sensitive layer, and is synthesized by radical polymerization. Temperature, viscoelasticity of the thermoreversible recording medium, easy molecular design from the viewpoint of controlling the transparency, it is possible to improve the erase energy width and heat resistance, etc., it is possible to suppress the aging change of the erase energy, In the case of the second embodiment and the fourth embodiment, the acrylic polyol resin is advantageous in that these advantages are more remarkable.
[0042]
The acrylic resin or the acrylic polyol resin, specifically, as a method for confirming that the resin used in the thermosensitive layer is the acrylic resin or the acrylic polyol resin, there is no particular limitation And various methods, for example, by comparing the absorption pattern of a standard acrylic resin with infrared absorption spectroscopy. Since the acrylic resin (the acrylic polyol resin) has a characteristic infrared absorption peak, for a certain resin, when the same infrared absorption peak as the acrylic resin (the acrylic polyol) can be detected, It can be confirmed that the resin is the acrylic resin (the acrylic polyol resin). Further, a copolymer of a (meth) acrylate monomer and another monomer (for example, an unsaturated monomer having a hydroxyl group) is obtained by peeling or shaving only the heat-sensitive layer and thermally decomposing the same by gas chromatography. Can be detected. By mass spectrometry, the monomer composition of the resin constituting the heat-sensitive layer can be specified, and as a result, it can be confirmed that the resin is the acrylic resin (acrylic polyol resin).
[0043]
Here, the acrylic resin is a resin obtained by copolymerizing a (meth) acrylic acid ester monomer and a monomer copolymerizable with the (meth) acrylic acid ester monomer. The content of the monomer is 50% by mass or more based on all the monomers.
Examples of the copolymerizable monomer include an unsaturated monomer having a carboxylic acid group, an unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomers.
[0044]
The (meth) acrylic acid ester monomer is not particularly limited and may be appropriately selected depending on the intended purpose. In general, monomers and oligomers used for an ultraviolet curing resin or an electron beam curing resin, etc. Preferred examples are given. Among these, those having a flexible structure are preferable, aliphatic compounds are preferable, and those having a chain structure are preferable for aromatic compounds.Moreover, monofunctional monomers to trifunctional or higher polyfunctional monomers are preferable. Bifunctional monomers are preferred.
Specific examples of the (meth) acrylic acid ester monomer include (meth) acrylic acid alkyl ester having an alkyl group, amino (meth) acrylic acid ester having an alkyl group, glycol di (meth) acrylic acid ester, and allyl. (Meth) acrylate, trimethylolpropane tri (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylonitribene (meth) acrylate, acrylamide, diacetone acrylamide, (meth) acrylonitrile , Benzyl (meth) acrylate, dimethylaminoethyl (meth) acrylate methyl chloride, allyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycidyl (meth) acrylate, etc. It is below. These may be used alone or in combination of two or more.
[0045]
The alkyl (meth) acrylate having an alkyl group is not particularly limited and may be appropriately selected depending on the purpose. For example, those having 1 to 18 carbon atoms are preferable, and those having 3 to 15 carbon atoms are preferable. Are more preferable, and specifically, methyl (meth)) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, cyclohexyl (meth) Acrylic esters, 2-ethylhexyl (meth) acrylic esters, lauryl (meth) acrylic esters, stearyl (meth) acrylic esters, and the like can be given.
If the carbon number of the alkyl group is too short, the flexibility of the acrylic resin may be lacking. If the carbon number is too long, methylene chains of side chains may be regularly arranged and the acrylic resin may lack flexibility. .
[0046]
The amino (meth) acrylate having an alkyl group is not particularly limited and can be appropriately selected depending on the intended purpose. For example, those having 1 to 5 carbon atoms are preferable, and specifically, dimethylamino Ethyl (meth) acrylate dimethylaminoethyl, (meth) acrylate and the like.
The glycol di (meth) acrylate is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, And the like.
[0047]
Among the (meth) acrylic acid ester monomers, the synthesized acrylic resin does not cause the “enthalpy relaxation” phenomenon, the shift of the glass transition temperature to a higher temperature side, and the like, and the acrylic resin is flexible. In view of having the above, the alkyl (meth) acrylate having the alkyl group is preferable, and among them, those having 1 to 18 carbon atoms are preferable, those having 3 to 15 carbon atoms are more preferable, and specifically, n-butyl (Meth) acrylate, i-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate And the like are particularly preferred.
Also, among the (meth) acrylic acid ester monomers, benzyl (meth) acryl acrylate is preferred because it can exhibit a high refractive index when adjusting the refractive index.
[0048]
The unsaturated monomer having a carboxylic acid group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include (meth) acrylic acid, itaconic acid, monobutyl itaconate, citraconic acid, and maleic acid. Monomethyl maleate, monobutyl maleate, 2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxypropyl succinate, 2- (meth) acryloyloxybutyl succinate, 2- (meth) acryloyl maleate Oxyethyl, 2- (meth) acryloyloxypropyl maleate, 4- (meth) acryloyloxybutyl maleate, 2-methacryloyloxyethyl hexahydrophthalate, and the like.
These may be used alone or in combination of two or more. Among these, unsaturated monomers containing a long-chain carboxylic acid such as 2-methacryloyloxyethyl hexahydrophthalate and 2- (meth) acryloyloxyethyl succinate are preferable in that the transparency of the thermoreversible recording medium can be improved. Are preferred.
[0049]
The unsaturated monomer having a hydroxyl group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ε-hydroxyalkyl (meth) acrylate and hydroxyalkyl (meth) acrylate. Caprolactone adduct, glycol di (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and alkyl (meth) acrylate. ) Acrylic esters and the like. Examples of the glycol di (meth) acrylate include ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, and the like.
The unsaturated monomer having a hydroxyl group can be suitably used when cross-linking with an isocyanate compound described below, and by appropriately selecting the structure of the isocyanate compound, it is possible to impart flexibility to the heat-sensitive layer. This is advantageous in that it can be performed. Among the unsaturated monomers having a hydroxyl group, 4-hydroxybutyl (meth) acrylate is particularly preferable in that it has excellent crosslinking reactivity with a polyisocyanate compound and long-term durability.
The hydroxyl valence (mg KOH / g, calculated solid) of the unsaturated monomer having a hydroxyl group is not particularly limited and may be appropriately selected depending on the purpose. For example, 20 to 130 mg KOH / g is preferable. .
[0050]
The other ethylenically unsaturated monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene, and acetic acid. Vinyl and vinyl propionate. These may be used alone or in combination of two or more. Among these, styrene is preferred because it can exhibit a high refractive index when adjusting the refractive index.
[0051]
In the present invention, among the acrylic resins, the (meth) acrylic acid ester monomer is synthesized by using at least 50% by mass based on the total monomers, and has a plurality of hydroxyl groups, such as an isocyanate compound. Akle polyol resins that can be crosslinked by a crosslinking agent are particularly preferred.
[0052]
The glass transition temperature of the acrylic polyol resin is preferably 30 ° C to 60 ° C, more preferably 40 ° C to a glass transition temperature (hereinafter sometimes referred to as “calculated Tg”) calculated from the following equation (Fox equation). 50 ° C. is more preferred.
When the calculated Tg is less than 30 ° C., the image heat resistance of the heat-sensitive layer is deteriorated, and the image may not be able to be sufficiently erased even when stored at a high temperature of room temperature or more. Repeat recording may be difficult.
[0053]
The formula (Fox) is represented by the following formula, 1 / Tg = Σ (Wi / Tgi).
In the above formula, “Tg” represents the calculated Tg, “Wi” represents the mass fraction of the monomer i, and “Tgi” represents the glass transition temperature Tg (K) of the homopolymer of the monomer i.
[0054]
The hydroxyl value (mg KOH / g, calculated solid value) of the acrylic polyol resin is not particularly limited and can be appropriately selected depending on the purpose. For example, 20 to 130 mg KOH / g is preferable, and 30 to 80 mg KOH / g is preferable. g is more preferred. If the hydroxyl value is less than 20 mgKOH / g, the long-term durability of the heat-sensitive layer may decrease. If it exceeds 130 mgKOH / g, a sufficient erasing energy width of the heat-sensitive layer may not be obtained.
The hydroxyl value (mg KOH / g, solid calculated value) of the acrylic polyol resin is, for example, potassium hydroxide required to neutralize acetic acid generated when reacted at a specified temperature for 1 hour using an acetylating agent. Can be measured by expressing in milligrams of the following formula, but it is calculated by the formula of {(hydroxyl × composition ratio) × 1000 × 56.1 (KOH)} / (hydroxyl monomer molecular weight × 100) according to the monomer composition of the resin. You can also.
[0055]
The acid value (AV) of the acrylic polyol resin is not particularly limited and may be appropriately selected depending on the purpose. For example, 1 to 10 mgKOH / g is preferable, and 3 to 8 mgKOH / g is more preferable. When the acid value (AV) is less than 1 mgKOH / g, the transparency of the heat-sensitive layer may be improved. When it exceeds 10 mgKOH / g, long-term durability may be deteriorated.
The acid value (AV) of the acrylic polyol resin is determined, for example, by dissolving a sample in a mixed solution of alcohol and toluene, titrating with a prescribed alcoholic potassium solution using phenolphthalein as an indicator, and containing the acid value in 1 g of the sample. The mg value of potassium hydroxide required to neutralize the acid used was calculated, and ｛acid value = A × f × (1/2) × (56.1 / 1000) × (1000 / sample (g)) (A represents the consumption amount (ml) of N / 2 alcoholic potassium hydroxide, and f represents the titer of the N / 2 alcoholic potassium hydroxide solution). Can be measured.
[0056]
The weight average molecular weight (Mw) of the acrylic polyol resin is not particularly limited and can be appropriately selected depending on the purpose. For example, 20,000 to 100,000 is preferable, and 40,000 to 60,000 is preferable. More preferred. If the weight average molecular weight is too low, the durability is deteriorated, and the erasing characteristics may fluctuate when stored for a long time.If the weight average molecular weight is too high, the erasing energy width for erasing a cloudy image with short heat energy is narrow. Sometimes it becomes.
The weight average molecular weight (Mw) of the acrylic polyol resin can be measured by, for example, a light scattering method or a GPC device (HLC-8220GPC manufactured by Tosoh Corporation).
[0057]
The refractive index of the acrylic polyol resin is not particularly limited, and can be appropriately selected according to the refractive index ratio with the organic low-molecular compound used in the thermosensitive layer of the thermoreversible recording medium. It is preferably from 0.45 to 1.60, more preferably from 1.48 to 1.55.
The refractive index of the acrylic polyol resin can be measured by, for example, a digital refractometer (manufactured by ATAGO, RX-2000) of a photorefractive critical angle detection method, or can be calculated from a monomer composition formula. It can also be calculated by a calculation formula using characteristic values of the polymer by the Synthia method.
Incidentally, the larger the refractive index ratio of the refractive index of the acrylic polyol resin and the refractive index of the organic low-molecular compound used in the thermosensitive layer of the thermoreversible recording medium, the higher the turbidity tends to increase, the smaller In this case, the transparency can be prevented from lowering due to the scattered light, and when it is near 1, (the difference in refractive index between the two is small), the erasability can be improved.
[0058]
The acrylic polyol resin includes the (meth) acrylic ester monomer, the unsaturated monomer having a carboxylic acid group, the unsaturated monomer having a hydroxyl group, and the other ethylenically unsaturated monomer. The compound can be synthesized according to a known solution polymerization method, suspension polymerization method, emulsion polymerization method or the like using the polymer. The method for supplying these monomers into the polymerization system is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include conventionally known methods.
[0059]
The acrylic resin is preferably cross-linked using a cross-linking agent from the viewpoint of improving the durability of image printing / erasing repeatedly. The crosslinking can be performed by, for example, heat, ultraviolet light, electron beam, or the like. Among these, crosslinking by heat or ultraviolet rays is preferred because it can be easily performed at low cost and does not require long-term storage for curing.
[0060]
The cross-linking agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include (meth) acrylic monomers and isocyanate compounds. These may be used alone or in combination of two or more. These may be appropriately synthesized or commercially available products. Among these, isocyanate compounds are preferred.
Specific examples of the combination of the acrylic resin and the crosslinking agent include (1) a combination of a thermoplastic resin having an acryloyl group or a methacryloyl group and a (meth) acrylic monomer, and (2) having a hydroxyl group. Suitable examples include a combination of an acrylic resin (acrylic polyol resin) and an isocyanate compound.
[0061]
In the case of the combination of the (1) thermoplastic resin having an acryloyl group or a methacryloyl group with a (meth) acrylic monomer, there are two cross-linking methods, and one is to mix and heat an organic peroxide. This is a method in which a radical is generated by reacting an acryloyl group or a methacryloyl group of a resin with a monomer to crosslink the resin, and another method is to mix a photopolymerization initiator and irradiate ultraviolet rays to generate a radical. In this method, the acryloyl group or methacryloyl group of the resin is caused to react with a monomer to crosslink the resin. Among these, the method using an organic peroxide is preferable since crosslinking can be performed by heat and expensive equipment is not required for crosslinking.
[0062]
In the case of the combination of (2) the acrylic resin having a hydroxyl group (acrylic polyol resin) and an isocyanate compound, it is preferable to use a polyisocyanate compound having a plurality of isocyanate groups as the isocyanate compound. Examples of the polyisocyanate compound include trimethylolpropane adducts and glycol adducts of diisocyanates selected from toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), and isophorone diisocyanate (IPDI). Lactone ester adduct, ether adduct, buret type, isocyanurate-bonded type, and block-type polyisocyanates thereof.
[0063]
Further, as the isocyanate compound, it is preferable to use at least a chain isocyanate compound, and a chain isocyanate compound and a cyclic isocyanate compound may be used in combination, and a mixture of both may be used. Is preferred.
When only the chain type isocyanate compound is used, generally, the crosslinked resin becomes flexible and the erasability is improved, but the repeated durability and image storability tend to decrease, while only the cyclic isocyanate compound is used. In such a case, the crosslinked resin generally becomes rigid, and although the repetition durability and image storability are improved, the erasability tends to decrease. Therefore, by using a mixture of the chain isocyanate compound and the cyclic isocyanate compound, it is possible to achieve both erasability, durability, and heat resistance.
[0064]
The chain isocyanate compound is not particularly limited and may be appropriately selected depending on the intended purpose.For example, a chain compound having a hydroxyl group such as a diol or a triol, and an aliphatic isocyanate such as hexamethylene diisocyanate may be used. And those obtained by reacting these via one or more ethylene oxide, propylene oxide, caprolactone or aliphatic polyester chains.
[0065]
The weight average molecular weight of the chain isocyanate compound is not particularly limited and can be appropriately selected depending on the purpose. For example, the lower limit is preferably 700 or more, and the upper limit is preferably 5,000 or less. , 4,000 or less, more preferably 3,000 or less. If the weight average molecular weight is too small, the flexibility of the crosslinked thermosensitive layer is deteriorated, and the erasability may be reduced.If the weight average molecular weight is too large, the molecule becomes difficult to move, and strength and durability are reduced. There is.
[0066]
In addition, as a weight average molecular weight per one isocyanate group, the lower limit is preferably 150 or more, more preferably 200 or more, particularly preferably 250 or more, and the upper limit is preferably 2,000 or less, and 1,500. The following is more preferred, and the 1,000 or less is particularly preferred. If the weight-average molecular weight per one isocyanate group is too small, the flexibility of the crosslinked thermosensitive layer is deteriorated, and the erasability may be reduced. Durability may decrease.
[0067]
The cyclic isocyanate compound is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an isocyanate compound having a benzene ring or an isocyanurate ring. These may be used alone or in combination of two or more. Among these, a cyclic isocyanate compound having an isocyanurate ring is preferable in that yellowing hardly occurs, and a compound having a chain structure such as an alkylene chain in addition to the cyclic structure is preferable.
[0068]
The weight average molecular weight of the cyclic isocyanate compound is not particularly limited and can be appropriately selected depending on the purpose. For example, the lower limit is preferably 100 or more, more preferably 200 or more, and particularly preferably 300 or more. The upper limit is preferably 1,000 or less, more preferably 700 or less. If the weight average molecular weight is too small, the film is evaporated by heating during the formation of the coating film and the coating film cannot be crosslinked, and the durability may be reduced.If the weight average molecular weight is too large, only a rigid structure can be formed. May decrease.
[0069]
The addition amount of the isocyanate compound is not particularly limited and may be appropriately selected depending on the purpose. For example, 1 to 50 parts by mass is preferable with respect to 100 parts by mass of the acrylic resin (the acrylic polyol resin). It is more preferably 3 to 50 parts by mass, particularly preferably 5 to 40 parts by mass. When the addition amount of the isocyanate compound is less than 1 part by mass, the elastic modulus at high temperature becomes low, and the coating film is destroyed by heating with a thermal head or the like. If it exceeds, the refractive index decreases, and the transparent density may decrease.
[0070]
The amount of the isocyanate group in the isocyanate compound with respect to the hydroxyl group in the acrylic resin (the acrylic polyol resin) is not particularly limited and can be appropriately selected depending on the purpose. For example, 0.05 to 1 equivalent is used. Preferably, 0.1 to 1.0 equivalent is more preferred. When the amount is less than 0.05 equivalent, the elastic modulus at high temperature is low, and the coating film is destroyed by heating with a thermal head or the like, so that the durability may be inferior. In some cases, the refractive index decreases, and the transparent density decreases.
[0071]
A catalyst can be used for the purpose of accelerating the curing reaction between the acrylic resin (the acrylic polyol resin) and the isocyanate compound. The catalyst is not particularly limited and may be appropriately selected depending on the intended purpose.Examples include triethylenediamine, cobalt naphthenate, stannous chloride, tetra-n-butyltin, varnish chloride, trimethyltin hydroxide, Dimethyl stannic chloride, di-n-butyltin dilaurate, and the like. These may be used alone or in combination of two or more.
The amount of the catalyst used is not particularly limited and may be appropriately selected depending on the purpose. For example, the amount is preferably 0.1 to 2% by mass based on the resin solid content.
[0072]
-Low molecular organic compound-
The molecular weight of the organic low-molecular compound is lower than that of the resin. For example, the weight average molecular weight is preferably 100 to 2,000, and more preferably 150 to 1,000.
When the weight-average molecular weight is less than 100, the melting point is too low and the outer organic low molecular weight compound may not be crystallized. May not be able to be melted by heating due to heat, and may not be able to be clouded.
The weight average molecular weight can be measured, for example, by liquid chromatography.
[0073]
The organic low-molecular weight compound is not particularly limited as long as it is in the form of particles in the heat-sensitive layer, and can be appropriately selected depending on the purpose. For example, oxygen, nitrogen, sulfur, and halogen atoms It is preferable to include at least one selected from the group consisting of -OH, -COOH, -CONH, -COOR, -NH, -NH ₂ , -S-, -SS-, -O-, a halogen atom and the like.
The melting point of the organic low molecular weight compound is not particularly limited and can be appropriately selected depending on the purpose. Usually, the temperature is preferably from 30 to 200 ° C, and more preferably from 50 to 150 ° C. When the melting point is less than 30 ° C., the melting point is low, and the organic low-molecular compound may not be sufficiently crystallized in cooling after heating, so that image formation / erasing may not be performed. The thermal sensitivity is increased, and the organic low-molecular weight compound cannot be melted by heating with a thermal head, so that an image cannot be formed.
[0074]
Suitable examples of the organic low-molecular weight compound include a carboxyl group-containing compound and a carboxyl group-free compound having no carboxyl group at the terminal (hereinafter abbreviated as “carboxyl group-free compound”). These may be used alone or in combination of two or more. Among these, even when stored in an environment where a trace amount of a basic substance such as ammonia or amine is present, the melting point does not increase, the cloudy saturation energy to cloudy saturation temperature does not shift from high energy to high temperature, and thermal sensitivity Compounds not containing a carboxyl group are particularly preferred, for example, from the viewpoint that image formation is not reduced and image formation becomes impossible.
[0075]
The carboxyl group-containing compound is not particularly limited and can be appropriately selected depending on the intended purpose.For example, a saturated monocarboxylic acid, a saturated dicarboxylic acid, an unsaturated monocarboxylic acid, an unsaturated dicarboxylic acid, a saturated halogen fatty acid, Examples include unsaturated halogen fatty acids, allyl carboxylic acids, halogen allyl carboxylic acids, thiocarboxylic acids, and the like. The number of carbon atoms is not particularly limited and can be appropriately selected depending on the purpose. For example, 10 to 60 is preferable, 10 to 38 is more preferable, and 10 to 30 is particularly preferable. These may be used alone or in combination of two or more. Among these, saturated or unsaturated monocarboxylic acids, saturated or unsaturated dicarboxylic acids, allylcarboxylic acids, halogen allylcarboxylic acids, and thiocarboxylic acids are preferred.
[0076]
Examples of the saturated or unsaturated monocarboxylic acid include higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, aragic acid, and oleic acid. No. As the saturated or unsaturated dicarboxylic acid, an aliphatic dicarboxylic acid having a melting point of about 100 to 135 ° C. is preferable, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane Diacid, dodecandioic acid, tetradecandioic acid, pentadecandioic acid, hexadecandioic acid, heptadecandioic acid, octadecandioic acid, nonadecandioic acid, eicosantioic acid, heneicosantioic acid, docosantioic acid, and the like.
[0077]
The carboxyl group-free compound is not particularly limited and can be appropriately selected depending on the intended purpose. For example, at least one selected from oxygen, nitrogen, sulfur and halogen atoms in the molecule (for example, -OH And a halogen atom, etc.). Specific examples thereof include alkanol, alkanediol, halogenalkanol, halogenalkanediol, alkylamine, alkane, alkene, alkyne, halogenalkane, halogenalkene, halogenalkyne, cycloalkane, and cycloalkane. Alkene, cycloalkyne, saturated monocarboxylic acid ester, saturated dicarboxylic acid ester, unsaturated monocarboxylic acid ester, unsaturated dicarboxylic acid ester, saturated monocarboxylic acid amide, saturated dicarboxylic acid amide, unsaturated monocarboxylic acid amide, unsaturated dicarboxylic acid Bonamide, saturated ammonium monocarboxylate, ammonium salt of saturated dicarboxylic acid, ammonium salt of unsaturated monocarboxylic acid, ammonium salt of unsaturated dicarboxylic acid, saturated halogen fatty acid ester, saturated halogen fatty acid amide, ammonium salt of saturated halogen fatty acid, unsaturated Halogen fatty acid ester, unsaturated halogen fatty acid amide, unsaturated halogen fatty acid ammonium salt, allyl carboxylic acid ester, allyl carboxylic acid amide, allyl carboxylic acid ammonium salt, halogen allyl carboxylic acid ester, halogen allyl carboxylic acid amide, halogen allyl carboxylic acid ammonium Salts, thioalcohols, thiocarboxylic acid esters, thiocarboxylic acid amides, thiocarboxylic acid ammonium salts, thioalcohol carboxylic acid esters, and the like. These may be used alone or in combination of two or more.
[0078]
The number of carbon atoms in the non-carboxyl group-containing compound is not particularly limited and can be appropriately selected depending on the purpose. For example, 10 to 60 is preferable, and 10 to 38 is more preferable. The alcohol group portion in the ester in the carboxyl group-free compound may be saturated or unsaturated, and may be substituted with a halogen atom.
[0079]
Among the non-carboxyl group-containing compounds, those having a melting point of 40 to 70 ° C. and a low melting point are preferable, and for example, fatty acid esters, dibasic acid esters, and polyhydric alcohol difatty acid esters are preferable.
[0080]
The fatty acid ester has a lower melting point than a fatty acid having the same number of carbon atoms (in a two-molecule association state) and conversely has a higher carbon number than a fatty acid having the same melting point. This is advantageous in that deterioration of printing-erasing can be suppressed, white turbidity can be increased, high contrast can be achieved, and durability can be repeatedly improved. The deterioration of printing and erasing of the image is considered to be caused by a change in the dispersed state of the particulate organic low-molecular compound due to compatibility between the resin and the organic low-molecular compound during heating.
In the present invention, the fatty acid ester and the high-melting point organic low-molecular compound are used in combination to form a mixture, whereby the transparency temperature range can be widened and the erasability with a thermal head can be improved. As a result, even if the erasability is slightly changed by storage, erasing can be sufficiently performed, and the durability can be repeatedly improved from the characteristics of the material itself.
[0081]
The fatty acid ester is not particularly limited and may be appropriately selected depending on the intended purpose. For example, those represented by the following structural formula (1) are preferable.
R ¹ -COO-R ² Structural formula (1)
In the structural formula (1), R ¹ And R ² May be the same or different, and represent an alkyl group having 10 or more carbon atoms. The fatty acid esters may be used alone or in a combination of two or more.
[0082]
The number of carbon atoms of the fatty acid ester is not particularly limited and can be appropriately selected depending on the purpose. For example, 20 or more is preferable, 25 or more is more preferable, and 30 or more is particularly preferable. As the number of carbon atoms increases, the degree of white turbidity increases, and the repeated durability improves.
The melting point of the fatty acid ester is not particularly limited and can be appropriately selected depending on the purpose. For example, 40 ° C. or higher is preferable.
[0083]
Specific examples of the fatty acid ester represented by the structural formula (1) include esters of higher fatty acids such as methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate and dodecyl behenate: C ₁₆ H ₃₃ -OC ₁₆ H ₃₃ , C ₁₆ H ₃₃ -SC ₁₆ H ₃₃ , C ₁₈ H ₃₇ -SC ₁₈ H ₃₇ , C ₁₂ H ₂₅ -SC ₁₂ H ₂₅ , C ₁₉ H ₃₉ -SC ₁₉ H ₃₉ , C ₁₂ H ₂₅ -S-S-C ₁₂ H ₂₅ And ethers and thioethers.
[0084]
The dibasic acid ester is not particularly limited and may be appropriately selected depending on the intended purpose. For example, any of a monoester and a diester may be used, and for example, represented by the following structural formula (2) Those are preferred.
R ³ OOC- (CH) _n -COOR ⁴ Structural formula (2)
In the structural formula (2), R ³ And R ⁴ May be the same or different, and represent a hydrogen atom or an alkyl group having 10 or more carbon atoms (provided that R ³ And R ⁴ Are not hydrogen atoms at the same time). R ³ And R ⁴ Is preferably 20 or more, more preferably 25 or more, and particularly preferably 30 or more. n is preferably 0 to 40, more preferably 1 to 30, and particularly preferably 2 to 20. In addition, the melting point of the dibasic acid ester is more preferably 40 ° C. or higher.
[0085]
The polyhydric alcohol difatty acid ester is not particularly limited and may be appropriately selected depending on the intended purpose. For example, those represented by the following structural formula (3) are preferable.
CH ₃ (CH ₂ ) _m -2COO (CH ₂ ) _p OOC (CH ₂ ) _m -2CH ₃ Structural formula (3)
In the structural formula (3), p is preferably 2 to 40, more preferably 3 to 30, and particularly preferably 4 to 22. m is preferably 2 to 40, more preferably 3 to 30, and particularly preferably 4 to 22.
[0086]
The polyhydric alcohol difatty acid ester has a lower melting point than a fatty acid having the same carbon number, and conversely has a higher carbon number than a fatty acid having the same melting point. -It is advantageous in that deterioration of erasure can be suppressed, white turbidity can be increased, high contrast can be achieved, and durability can be repeatedly improved.
[0087]
As the organic low-molecular compound, a low-melting organic low-molecular compound and a high-melting organic low-molecular compound having a melting point higher than that of the low-melting organic low-molecular compound are combined and used. Is preferred in that it can be further expanded. The difference between the melting point of the low-melting point organic low-molecular compound and the melting point of the high-melting point organic low-molecular compound is not particularly limited and can be appropriately selected depending on the intended purpose. C. or higher is more preferable, and 50 C or higher is particularly preferable.
[0088]
The melting point of the low-melting organic low-molecular compound is not particularly limited and can be appropriately selected depending on the purpose. For example, 40 ° C to 100 ° C is preferable, and 50 ° C to 80 ° C is more preferable. The melting point of the high-melting organic low-molecular compound is not particularly limited and may be appropriately selected depending on the purpose. For example, 100 ° C to 200 ° C is preferable, and 110 ° C to 180 ° C is more preferable.
[0089]
The high melting point organic low molecular weight compound is preferably one having a melting point of 100 ° C. or higher, for example, aliphatic saturated dicarboxylic acid, ketone having a higher alkyl group, semicarbazone derived from the ketone, α-phosphono fatty acid, etc. Is mentioned. These may be used alone or in combination of two or more.
[0090]
Examples of the aliphatic saturated dicarboxylic acid include, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tetradecandioic acid, pentadecandioic acid, and hexadecandiodic acid. Acids, heptadecandioic acid, octadecandioic acid, nonadecandioic acid, eicosandioic acid, heneicosandioic acid, docosandioic acid, and the like.
Examples of the ketone include those that contain a ketone group and a higher alkyl group as essential constituent groups, and those that further contain an unsubstituted or substituted aromatic ring or an elementary ring. The total carbon number of the ketone is preferably 16 or more, more preferably 21 or more. The semicarbazone is derived from the ketone.
The α-phosphono fatty acid is, for example, E. coli. V. Kaurer et al. Ak. In accordance with the method of Oil Chemist's Soc, 41, 205 (1964), the fatty acid is brominated by the Hall-Volhard-Zelinskin reaction to obtain α-brominated acid bromide. Next, ethanol is added to the α-brominated acid bromide to obtain an α-bromo fatty acid ester. Next, the α-bromo fatty acid ester is heated and reacted with triethyl phosphite to form an α-phosphono fatty acid ester, which is hydrolyzed with concentrated hydrochloric acid to recrystallize the α-phosphono fatty acid as a product from toluene. As described above, α-phosphono fatty acid can be synthesized.
[0091]
In the present invention, the organic low-molecular weight compound may be appropriately combined, or the organic low-molecular weight compound may be combined with another material having a different melting point for the purpose of expanding the transparentization temperature range.
[0092]
The mixing mass ratio (organic low molecular weight compound: acrylic resin) of the organic low molecular weight compound and the acrylic resin (resin having a crosslinked structure) in the heat sensitive layer is not particularly limited and may be appropriately selected depending on the purpose. For example, 2: 1 to 1:16 is preferable, and 1: 2 to 1: 8 is more preferable.
When the mass ratio is within the above numerical range, it may be difficult to disperse the organic low-molecular compound in the resin, or it may be difficult to make the organic low-molecular compound opaque.
[0093]
In the present invention, when the fatty acid ester is used as the low-melting-point organic low-molecular-weight compound, a high-melting-point organic low-molecular-weight compound having a higher melting point than the low-melting-point fatty acid ester for the purpose of expanding the range of the clearing temperature It is preferable to mix and use with a straight chain hydrocarbon-containing compound. In this case, it is possible to improve the image erasing (transparency) by heating in a short time by a thermal head or the like, and further increase the margin of image erasing. This is advantageous in that erasing with a thermal head becomes possible without causing any problem.
[0094]
The straight-chain hydrocarbon-containing compound preferably has a total carbon number of 6 to 60, more preferably 8 to 50, and among them, cyclic hydrocarbon (for example, cyclohexane, cyclopentane, etc.), aromatic Group rings (eg, benzene, naphthalene, etc.), heterocycles (eg, cyclic ether, furan, pyran, morpholine, pyrrolidine, piperidine, pyrrole, pyridine, pyrazine, piperazine, pyrimidine, etc.), fused heterocycles (eg, benzopyrrolidine, indole) , Benzoxazine, quinoline, etc.) are preferable, and those having a phenylene structure (eg, a phenyl group), a cyclohexylene structure (eg, a cyclohexyl group), or a heterocyclic ring are more preferable. Those having at least one methyl group are particularly preferred.
[0095]
Specific examples of the linear hydrocarbon-containing compound include (1) a linear hydrocarbon-containing compound having a urethane bond, (2) a linear hydrocarbon-containing compound having a sulfonyl bond, and (3) having an oxalic acid diamide bond. A linear hydrocarbon-containing compound, (4) a linear hydrocarbon-containing compound having a diacylhydrazide bond, (5) a linear hydrocarbon-containing aliphatic compound having a urea bond and a urethane bond, and (6) a urea bond and an amide bond. (7) linear hydrocarbon-containing aliphatic compound having a plurality of urea bonds, (8) cyclic compound having a urea bond, (9) cyclic compound containing an amide bond And the like.
As the linear hydrocarbon-containing compound according to any one of the above (1) to (9), a compound having no carboxyl group is preferable, and a urethane bond (—NHCOO—) and a sulfonyl bond (—SO ₂ −), An amide bond (—CONH—), an oxalic acid diamide bond (—NHCOCONH—), a diacylhydrazide bond (—CONHNHCO—), or a compound having a polar group such as a urea bond (—HNCONH—). .
[0096]
The lower limit of the melting point of the linear hydrocarbon-containing compound is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, particularly preferably 130 ° C. or higher, and the upper limit is 180 ° C. or lower. Is preferably 160 ° C. or lower, more preferably 150 ° C. or lower. If the melting point is too low, the clarification temperature range cannot be expanded, and the erasability may decrease. If the melting point is too high, the sensitivity in forming a cloudy image may decrease.
[0097]
Examples of the linear hydrocarbon-containing compound include compounds represented by any of the following structural formulas (4) to (9).
R ⁵ -X-R ⁶ -Y-R ⁷ Structural formula (4)
In the structural formula (4), at least one of X and Y represents a urethane bond, a sulfonyl bond, or a urea bond, and the rest represents one selected from a urethane bond, a sulfonyl bond, a urea bond, and an amide bond. . R ⁵ And R ⁷ Is CH ₃ (CH ₂ ) _m -Or CH ₃ (CH ₂ ) _m -O- (CH ₂ ) _n -Represents R ⁶ Is-(CH ₂ ) _m -Represents any group of the following structural formulas (4-1) to (4-2).
[0098]
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In the structural formulas (4-1) and (4-2), m and n are preferably 0 to 30.
[0099]
R ⁸ -X-R ⁹ Structural formula (5)
In the structural formula (5), X represents an oxalic acid diamide bond or a diacyl hydrazide bond. R ⁸ And R ⁹ Is CH ₃ (CH ₂ ) _m -Or CH ₃ (CH ₂ ) _m -O- (CH ₂ ) _n Represents-. m and n represent an integer of 0 to 30.
[0100]
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In the structural formula (6), X and Y represent at least one selected from a urethane bond, a sulfonyl bond, a urea bond, an amide bond, an oxalic acid diamide bond, and a diacyl hydrazide bond. R ¹⁰ And R ¹² Is-(CH ₂ ) _m -Or-(CH ₂ ) _m -O- (CH ₂ ) _n Represents-. R ¹¹ Is CH ₃ (CH ₂ ) _m -Or CH ₃ (CH ₂ ) _m -O- (CH ₂ ) _n Represents-. m and n represent an integer of 0 to 30. A represents a phenyl group, a cyclohexyl group, or any one of the following structural formulas (6-1) to (6-2).
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In the structural formula (7), X represents a urethane bond, a sulfonyl bond, a urea bond, an amide bond, an oxalic acid diamide bond, or a diacyl hydrazide bond. R ¹⁰ And R ¹² Is-(CH ₂ ) _m -Or-(CH ₂ ) _m -O- (CH ₂ ) _n Represents-. m and n represent an integer of 0 to 30. A represents a phenyl group, a cyclohexyl group, or any one of the following structural formulas (6-1) to (6-2).
[0101]
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[0102]
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In the structural formula (6-2), 1 represents an integer of 1 to 3. Z is R ¹³ OCO-, R ¹³ O- or R ¹³ Represents-. R ¹³ Is CH ₃ (CH ₂ ) _m -Or CH ₃ (CH ₂ ) _m -O- (CH ₂ ) _n Represents-. m and n represent an integer of 0 to 30.
[0103]
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[0104]
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[0105]
In the structural formulas (8) and (9), X represents any one selected from a urethane bond, a sulfonyl bond, a urea bond, an amide bond, an oxalic acid diamide bond, and a diacyl hydrazide bond. R ¹⁴ Is-(CH ₂ ) _m -Or-(CH ₂ ) _m -O- (CH ₂ ) _n Represents-. R ^Fifteen Is CH ₃ (CH ₂ ) _m -Or CH ₃ (CH ₂ ) _m -O- (CH ₂ ) _n Represents-. m and n represent an integer of 0 to 30.
[0106]
Preferred specific examples of the linear hydrocarbon-containing compound include compounds represented by any of the following structural formulas (10) to (26).
R ¹⁶ -OOCNH-R ¹⁷ -NHCOO-R ¹⁸ Structural formula (10)
R ¹⁶ -NHCOO-R ¹⁷ -OOCNH-R ¹⁸ Structural formula (11)
R ¹⁶ -SO ₂ -R ¹⁷ -SO ₂ -R ¹⁸ Structural formula (12)
R ¹⁶ -NHCOCONH-R ¹⁸ Structural formula (13)
R ¹⁶ -CONHNHCO-R ¹⁸ Structural formula (14)
R ¹⁶ -NHCO-R ¹⁷ -NHCONH-R ¹⁸ Structural formula (15)
R ¹⁶ -CONH-R ¹⁷ -NHCONH-R ¹⁸ Structural formula (16)
R ¹⁶ -NHCOO-R ¹⁷ -NHCONH-R ¹⁸ Structural formula (17)
R ¹⁶ -NHCONH-R ¹⁷ -NHCONH-R ¹⁸ Structural formula (18)
R ¹⁶ -NHCOO-R ¹⁷ -OOCNH-R ¹⁸ Structural formula (19)
However, in the structural formulas (10) to (19), R ¹⁶ And R ¹⁸ Represents an alkyl group. R ¹⁷ Represents a methylene group or a group represented by the following structural formula (10-1) or the following structural formula (10-2).
[0107]
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However, in the structural formulas (10-1) to (10-2), m and n represent an integer of 0 to 20.
[0108]
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[0109]
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[0110]
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[0111]
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[0112]
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[0113]
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[0114]
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[0115]
Preferred specific examples of the compound represented by the structural formula (10) include the following.
CH ₃ (CH ₂ ) ₁₁ OOCNH (CH ₂ ) ₆ NHCOO (CH ₂ ) ₁₁ CH ₃ Melting point: 113 ° C
CH ₃ (CH ₂ ) ₁₇ OOCNH (CH ₂ ) ₆ NHCOO (CH ₂ ) ₁₇ CH ₃ Melting point: 119 ° C
CH ₃ (CH ₂ ) ₂₁ OOCNH (CH ₂ ) ₆ NHCOO (CH ₂ ) ₂₁ CH ₃ Melting point: 121 ° C
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[0116]
Preferred specific examples of the compound represented by the structural formula (11) include the following.
CH ₃ (CH ₂ ) ₁₇ NHCOO (CH ₂ ) ₂ OOCNH (CH ₂ ) ₁₇ CH ₃ Melting point: 115 ° C
CH ₃ (CH ₂ ) ₁₇ NHCOO (CH ₂ ) ₄ OOCNH (CH ₂ ) ₁₇ CH ₃ Melting point: 119 ° C
CH ₃ (CH ₂ ) ₁₇ NHCOO (CH ₂ ) ₆ OOCNH (CH ₂ ) ₁₇ CH ₃ Melting point: 111 ° C
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[0117]
Preferred specific examples of the compound represented by the structural formula (12) include the following.

[0118]
Preferred specific examples of the compound represented by the structural formula (13) include the following.

[0119]
Preferred specific examples of the compound represented by the structural formula (14) include the following.

[0120]
Preferred specific examples of the compound represented by the structural formula (15) include the following.
CH ₃ (CH ₂ ) ₁₇ NHCO (CH ₂ ) ₄ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 144 ° C
CH ₃ O (CH ₂ ) ₃ NHCO (CH ₂ ) ₁₁ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 140 ° C
CH ₃ CH ₂ O (CH ₂ ) ₃ NHCO (CH ₂ ) ₁₁ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 135 ° C
[0121]
Preferred specific examples of the compound represented by the structural formula (16) include the following.
CH ₃ (CH ₂ ) ₁₆ CONH (CH ₂ ) ₆ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 149 ° C
[0122]
Preferred specific examples of the compound represented by the structural formula (17) include the following.
CH ₃ (CH ₂ ) ₁₇ NHCOO (CH ₂ ) ₂ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 127 ° C
[0123]
Preferred specific examples of the compound represented by the structural formula (18) include the following.
CH ₃ (CH ₂ ) ₁₇ NHCONH (CH ₂ ) ₆ NHCONH (CH ₂ ) ₁₇ CH ₃ Melting point: 177 ° C
[0124]
Preferred specific examples of the compound represented by the structural formula (19) include the following.
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[0125]
Preferred specific examples of the compound represented by the structural formula (20) include the following.
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[0126]
Preferred specific examples of the compound represented by the structural formula (22) include the following.
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[0127]
Preferred specific examples of the compound represented by the structural formula (23) include the following.
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[0128]
Preferred specific examples of the compound represented by the structural formula (24) include the following.
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[0129]
Preferred specific examples of the compound represented by the structural formula (25) include the following.
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[0130]
Preferred specific examples of the compound represented by the structural formula (26) include the following.
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[0131]
The mixing mass ratio of the straight-chain hydrocarbon-containing compound to the low-melting organic low-molecular compound (low-melting organic low-molecular compound: straight-chain hydrocarbon-containing compound) is not particularly limited, and may be appropriately determined according to the purpose. For example, 95: 5 to 5:95 is preferable, 90:10 to 10:90 is more preferable, and 80:20 to 20:80 is particularly preferable. If the mixing mass ratio is not within the numerical range, when the amount of the low-melting organic low-molecular compound is too large, the clearing temperature range is narrowed, the erasability may not be sufficient, and the straight-chain hydrocarbon-containing When there are too many compounds, an image may not be able to be formed.
[0132]
In addition to the low-melting organic low-molecular compound or the high-melting organic low-molecular compound, when other organic low-molecular compounds are used in combination, the other organic low-molecular compounds are not particularly limited and may be used according to the purpose. It can be appropriately selected and includes, for example, higher fatty acids, esters of higher fatty acids, ethers of higher fatty acids, and the like.
Examples of the higher fatty acids include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, araginic acid, and oleic acid. Examples of the ester of the higher fatty acid include methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, dodecyl behenate, and the like. Examples of the ether of the higher fatty acid include, for example, C ₁₆ H ₃₃ -OC ₁₆ H ₃₃ , And the like. As the thioether of the higher fatty acid, for example, C ₁₆ H ₃₃ -SC ₁₆ H ₃₃ , C ₁₈ H ₃₇ -SC ₁₈ H ₃₇ , C ₁₂ H ₂₅ -SC ₁₂ H ₂₅ , C ₁₉ H ₃₉ -SC ₁₉ H ₃₉ , C ₁₂ H ₂₅ -S-S-C ₁₂ H ₂₅ , And the like. These may be used alone or in combination of two or more. Among these, higher fatty acids, particularly higher fatty acids having 16 or more carbon atoms such as palmitic acid, pentadecanoic acid, nonadecanoic acid, arachinic acid, stearic acid, behenic acid, and lignoceric acid are preferable, and higher fatty acids having 16 to 24 carbon atoms are further preferable. preferable.
[0133]
Other components in the heat-sensitive layer are not particularly limited and may be appropriately selected depending on the purpose. For example, from the viewpoint of facilitating image formation, a surfactant, a plasticizer, and the like are exemplified.
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. No.
The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a phosphate ester, a fatty acid ester, a phthalate ester, a dibasic ester, a glycol, a polyester plasticizer, and an epoxy plasticizer. Agents, and the like.
[0134]
The thickness of the heat-sensitive layer is not particularly limited and can be appropriately selected depending on the purpose. For example, 1 to 30 μm is preferable, and 2 to 20 μm is more preferable.
If the thickness of the heat-sensitive layer is too small, the turbidity may be reduced and the contrast may be lowered.If the thickness is too thick, heat distribution in the layer may occur and it may be difficult to achieve uniform transparency. is there. The turbidity can be increased by increasing the content of the organic low-molecular compound in the thermosensitive layer.
[0135]
The thermoreversible recording medium of the present invention may further comprise a support, a coloring layer, an air layer, a light reflection layer, an adhesive layer, an intermediate layer, a protective layer, and an adhesive layer, which are appropriately selected as needed in addition to the heat-sensitive layer. And other layers such as an adhesive layer. Each of these layers may have a single-layer structure or a laminated structure.
[0136]
The layer configuration of the thermoreversible recording medium is not particularly limited and can be appropriately selected depending on the purpose. For example, as described in JP-A-2-3876, a heat-sensitive JP-A-3-130188, which has a layer and a magnetic thermosensitive layer containing a magnetic material as a main component, and at least a portion directly under the thermosensitive layer or a portion corresponding to the thermosensitive layer of the support is colored, as described in JP-A-3-130188. A magnetic thermosensitive layer on a support, a light reflecting layer on the magnetic thermosensitive layer, a layer configuration in which a thermosensitive layer is provided on the light reflecting layer, and the like. The layer is preferably provided on the back side of the support or between the support and the thermosensitive layer.
[0137]
The shape, structure, size, and the like of the support are not particularly limited and can be appropriately selected depending on the purpose. Examples of the shape include a flat plate and the like. The size may be appropriately selected according to the size of the thermoreversible recording medium and the like.
Examples of the material of the support include an inorganic material and an organic material. As the inorganic material, for example, glass, quartz, silicon, silicon oxide, aluminum oxide, SiO ₂ , Metals and the like. Examples of the organic material include paper, polyethylene terephthalate, polycarbonate, polystyrene, polymethyl methacrylate, and the like. These may be used alone or in combination of two or more.
The thickness of the support is not particularly limited and may be appropriately selected depending on the purpose. The thickness is preferably 100 to 2,000 μm, more preferably 100 to 1,000 μm.
[0138]
The thermoreversible recording medium may be provided with a protective layer for the purpose of protecting the thermosensitive layer. Examples of the material for the protective layer include silicone rubber, silicone resin (for example, JP-A-63-221087), polysiloxane graft polymer (for example, JP-A-63-317385), ultraviolet curable resin, and electron beam curable resin. Resin (for example, JP-A-2-566).
When applying these materials, a solvent is usually used. The solvent is preferably one that does not easily dissolve the resin and the organic low-molecular compound in the heat-sensitive layer, and examples thereof include alcohol solvents such as n-hexane, methyl alcohol, ethyl alcohol, and isopropyl alcohol. These may be used alone or in combination of two or more. Alcohol solvents are preferred in view of cost.
[0139]
The protective layer can be cured at the same time as the acrylic resin of the heat-sensitive layer is cured. In this case, after forming the heat-sensitive layer on the support, the protective layer is applied and dried. Then, heat, ultraviolet rays, electron beam irradiation, etc. are performed to cure each layer.
The thickness of the protective layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the thickness is preferably 0.1 to 10.0 μm. If the thickness of the protective layer is less than 0.1 μm, the protective effect of the heat-sensitive layer may not be sufficient, and if it exceeds 10.0 μm, the thermal sensitivity may decrease.
[0140]
In the thermoreversible recording medium, an intermediate layer can be provided between the protective layer and the thermosensitive layer for the purpose of protecting the thermosensitive layer from a solvent, a monomer component, and the like of the protective layer forming liquid (for example, 1-113381 gazette). As the material of the intermediate layer, a resin component such as a thermoplastic resin or a thermosetting resin can be used in addition to those listed as the material of the resin in the thermosensitive layer. Examples of the resin component include polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide, and the like.
The thickness of the intermediate layer is not particularly limited and can be appropriately selected depending on the purpose.
[0141]
The thermoreversible recording medium is preferably provided with a colored layer between the support and the thermosensitive layer for the purpose of improving visibility. The colored layer can be formed by applying a solution or a dispersion containing a colorant and a resin binder to the target surface and drying, or simply attaching a colored sheet.
The colorant is not particularly limited as long as the change in transparency and white turbidity of the heat-sensitive layer, which is the upper layer, can be recognized as a reflection image, and for example, red, yellow, blue, dark blue, purple, black, brown, gray Dyes and pigments having colors such as orange, green and the like are used. As the resin binder, various thermoplastic resins, thermosetting resins, ultraviolet curable resins, and the like are used.
[0142]
In the thermoreversible recording medium, a color printing layer can be provided.Examples of the colorant in the color printing layer include various dyes and pigments contained in color inks used in conventional full-color printing. Examples of the resin binder include various thermoplastic, thermosetting, ultraviolet curable or electron beam curable resins. Since the thickness of the color print layer is appropriately changed with respect to the print color density, it can be selected according to the desired print color density.
[0143]
The thermoreversible recording medium may have a non-adhesion part by an air layer between the support and the thermosensitive layer. The refractive index of the organic polymer compound used for the heat-sensitive layer is about 1.4 to 1.6, and the difference from the refractive index of air is large. Light is reflected at the interface between the heat-sensitive layer and the non-contact portion, and when the heat-sensitive layer is in a cloudy state, the degree of white turbidity can be amplified. Can be suitably used.
Since the air layer also functions as a heat insulating layer, it can improve the degree of heat sensitivity, and also functions as a cushion layer, can disperse the pressure from a thermal head, and deforms and particles the heat sensitive layer. It is possible to prevent diffusion of the organic low-molecular compound in the form of, for example, and to improve durability repeatedly.
[0144]
Further, the thermoreversible recording medium may be provided with a head matching layer. Examples of the material of the head matching layer include a heat-resistant resin and an inorganic pigment. As the heat-resistant resin, the same heat-resistant resin used in the protective layer is preferably used. Examples of the inorganic pigment include calcium carbonate, kaolin, silica, aluminum hydroxide, alumina, aluminum silicate, magnesium hydroxide, magnesium carbonate, magnesium oxide, titanium oxide, zinc oxide, barium sulfate, and talc. . These may be used alone or in combination of two or more. The particle size of the inorganic pigment is, for example, preferably 0.01 to 10.0 μm, and more preferably 0.05 to 8.0 μm. The amount of the inorganic pigment to be added is preferably 0.001 to 2 parts by mass, more preferably 0.005 to 1 part by mass, per 1 part by mass of the heat-resistant resin.
[0145]
When the resin contained in the protective layer, the color printing layer, and the head matching layer is cured by heat, ultraviolet light, electron beam, or the like, the crosslinking used for crosslinking the resin of the heat-sensitive layer with ultraviolet light is used. It is preferable to add an agent, a photopolymerization initiator, and a photopolymerization accelerator.
[0146]
The method for producing the thermoreversible recording medium is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) the resin and the organic low-molecular compound are dissolved or dispersed in a solvent. A method of coating the composition for a thermoreversible recording medium on a support, and evaporating the solvent to form a sheet or the like at the same time or at the same time followed by crosslinking; A method in which a composition for a thermoreversible recording medium in which a molecular compound is dispersed is coated on a support, and the solvent is evaporated to form a sheet or the like and crosslinked at the same time or thereafter, and (3) the resin is used without using a solvent. And the above-mentioned organic low-molecular compound are heated and melted and mixed with each other, and the resulting molten mixture is formed into a sheet or the like, cooled, and then crosslinked, and the like. Incidentally, in these, it is also possible to form a sheet-like thermoreversible recording medium without using the support.
[0147]
The solvent used in the above (1) or (2) differs depending on the type of the resin and the organic low molecular weight compound and cannot be unconditionally specified. For example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, chloroform, Examples thereof include carbon chloride, ethanol, toluene, and benzene.
The organic low-molecular compound is present in the heat-sensitive layer in the form of particles dispersed therein.
[0148]
In the thermoreversible recording medium composition, various pigments, defoaming agents, pigments, dispersants, slip agents, preservatives, cross-linking agents, plasticizers, and the like, for the purpose of expressing advanced performance for coating materials. It may be added.
The method for applying the composition for a thermoreversible recording medium is not particularly limited and can be appropriately selected from known methods, for example, a spray coating method, a roller coating method, a bar coating method, an air knife coating method, A brush coating method, a dipping method and the like can be mentioned.
The drying conditions of the composition for a thermoreversible recording medium are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include room temperature to 140 ° C. and about 10 minutes to 1 hour. Can be
[0149]
The resin in the heat-sensitive layer can be cured by heating, ultraviolet irradiation, electron beam irradiation, or the like. As a method of curing by these means, specifically, curing is performed by reacting an acrylic copolymer (acrylic resin) with a polyisocyanate compound.
[0150]
The ultraviolet irradiation can be performed using a known ultraviolet irradiation device, and examples of the device include those provided with a light source, a lamp, a power supply, a cooling device, a transport device, and the like.
Examples of the light source include a mercury lamp, a metal halide lamp, a potassium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator added to the composition for a thermoreversible recording medium.
The conditions for the ultraviolet irradiation are not particularly limited and may be appropriately selected depending on the intended purpose.For example, the lamp output, the transport speed, and the like may be determined according to the irradiation energy required for crosslinking the resin. .
[0151]
The electron beam irradiation can be performed using a known electron beam irradiation device, and the electron beam irradiation device can be roughly classified into two types, a scanning type (scan beam) and a non-scanning type (area beam). Conditions can be selected according to the irradiation area, irradiation dose, and the like. The electron beam irradiation condition can be determined from the following formula in consideration of the electron flow, irradiation width, and transport speed according to the dose required for crosslinking the resin.
D = (△ E / △ R) · η · I / (W · V)
In the above formula, D represents a required dose (Mrad). ΔE / ΔR represents the average energy loss. η represents efficiency. I represents the electron current (mA). W represents the irradiation width (cm). V represents the transport speed (cm / s).
Note that, industrially, it is preferable to simplify the above formula and use the following formula.
DV = KI / W
The device rating is represented by Mrad · m / min, and the electron flow rating is selected to be about 20 to 500 mA.
[0152]
When the resin in the heat-sensitive layer is cured, the hardness of the heat-sensitive layer can be improved. In the case where heating is performed simultaneously while applying pressure using a thermal head or the like, the resin around the organic low-molecular compound in the form of particles is deformed and the finely dispersed organic compound is dispersed during repeated image formation and erasing. The low molecular compound gradually becomes particles having a large diameter, the effect of scattering light is reduced (the turbidity is reduced), and finally, the image contrast is reduced. Therefore, the hardness of the heat-sensitive layer is important for the durability of the heat-sensitive layer, and the higher the hardness of the heat-sensitive layer, the better the durability. Further, it is better that the heat-sensitive layer at the time of heating (100 to 140 ° C.) is hard, and the hardness of the heat-sensitive layer can be measured using, for example, a thin film hardness meter MHA-400 manufactured by NEC.
[0153]
Further, if a void having a different refractive index exists at the interface between the resin and the particles of the organic low-molecular compound in the heat-sensitive layer and / or inside the organic low-molecular compound in the form of particles, the image density in a cloudy state is obtained. And contrast can be improved. In this case, the size of the gap is preferably at least 1/10 of the wavelength of light used for detecting the opaque state.
[0154]
The image formed on the thermoreversible recording medium may be visible as a transmission image, or may be visible as a reflection image.
When used as the reflection image, it is preferable to provide a reflection layer for reflecting light on the back surface of the heat-sensitive layer. In this case, it is advantageous in that the thickness of the heat-sensitive layer can be reduced, and the contrast can be increased even if the thickness of the heat-sensitive layer is reduced. The reflective layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a layer on which Al, Ni, Sn, or the like is deposited (for example, JP-A-64-14079). reference).
[0155]
The thermoreversible recording medium can selectively heat the heat-sensitive layer by selectively applying heat to form a cloudy image on a transparent ground, and a transparent image on a cloudy ground, and the change is repeated many times. It is possible to do. If a colored sheet is arranged on the back of the heat-sensitive layer, an image of the color of the colored sheet on a white background or an image of a white background on the ground of the color of the colored sheet can be formed. Further, when projected by an OHP (overhead projector) or the like, the cloudy portion becomes a dark portion, the transparent portion transmits light, and becomes a bright portion on the screen.
[0156]
The formation and erasing of an image on the thermoreversible recording medium can be performed by using a known image processing apparatus, and is preferably performed by using an image processing apparatus of the present invention described later. For example, the heat-sensitive layer contains the resin and an organic low-molecular compound dispersed in the resin, and has a temperature of “T ₀ At normal temperatures below, it is in a "cloudy" state (opaque). As the heat-sensitive layer is heated, the temperature “T ₁ ”And gradually begin to become transparent, and the temperature“ T ₂ "~" T ₃ ”, The thermosensitive layer becomes“ transparent ”. From this “transparent” state, ₀ The temperature-sensitive layer is maintained in the "transparent" state even when the temperature is returned to the normal temperature below. That is, the temperature “T ₁ ), The resin starts to soften, and as the temperature rises, the resin and the organic low molecular weight compound expand together, but the organic low molecular weight compound has a larger degree of expansion than the resin, The low molecular compound gradually reduces the voids at the interface with the resin, resulting in a gradual increase in transparency. Temperature "T ₂ "~" T ₃ In the above, the organic low-molecular compound is in a semi-molten state, and the remaining voids are filled with the semi-molten organic low-molecular compound to be in a “transparent” state. When the heat-sensitive layer is cooled in this state, the organic low-molecular compound crystallizes at a relatively high temperature and changes in volume. At this time, since the resin is in a softened state, it is possible to follow a change in volume due to crystallization of the organic low-molecular compound, and no void is generated at the interface between the organic low-molecular compound and the resin, and thus “transparent” The state is maintained. Further, the heat-sensitive layer is heated at a temperature “T ₄ Above, the thermosensitive layer will be in a "translucent" state intermediate between maximum transparency and maximum opacity. Next, when the temperature is lowered, the state becomes "opaque" (opaque) without becoming "transparent". That is, when the organic low-molecular-weight compound has a temperature “T ₄ After completely melting at the temperature above “T ₀ Crystallizes at slightly higher temperatures. At this time, the resin cannot follow the volume change due to the crystallization of the organic low-molecular compound, and a void is formed at the interface between the organic low-molecular compound and the resin, so that the resin becomes “white turbid”.
[0157]
As the image processing device, for example, an image forming device for forming an image on the thermoreversible recording medium, and a device having an image erasing device for erasing an image are preferable. Among these, the one provided with an image forming and erasing unit which also serves as the image forming unit and the image erasing unit is preferable in that the processing time is short. Specifically, a thermal head is used. An image processing apparatus or an image forming unit capable of processing an image by changing the energy applied to the image forming unit is a thermal head, and the image erasing unit is a thermal head, a ceramic heater (a heating resistor is screen-printed on an alumina substrate). Heating element), hot stamp, heat roller, heat block, etc. And the like such as an image processing apparatus is selected from one of the non-contact type means had.
[0158]
In the thermoreversible recording medium of the present invention, the thermosensitive layer capable of reversible display and the information storage section are provided (integrated) on the same card, and a part of the information stored in the information storage section is displayed on the thermosensitive layer. Thereby, the card holder can check the information only by looking at the card without using any special device, which is excellent in convenience.
The information storage unit is not particularly limited, but is preferably, for example, magnetic recording, IC, non-contact IC, or optical memory. As the heat-sensitive layer, commonly used iron oxide, barium ferrite or the like and a vinyl chloride-based or urethane-based resin, a nylon-based resin, or the like, is coated and formed on a support, or a resin is formed by a method such as evaporation or sputtering. It is formed without using. The heat-sensitive layer may be provided on the surface of the support opposite to the heat-sensitive layer, or may be provided between the support and the heat-sensitive layer or on a part of the heat-sensitive layer. Further, a reversible thermosensitive material used for display may be used for the storage unit by a barcode, a two-dimensional code, or the like. Of these, magnetic recording and IC are more preferred.
[0159]
According to the thermoreversible recording medium of the present invention, an image is sufficiently erased even when heated for a minimum time of milliseconds using a thermal head, and the erasing energy does not change after image formation, so that sufficient erasability is maintained. Even when left at a high temperature for a long time, an image having excellent storage stability, contrast, visibility and the like is formed.
The thermoreversible recording medium can be suitably used for various rewritable point cards and the like, and is particularly preferably used for the following thermoreversible recording labels, thermoreversible members, image processing apparatuses, image processing methods, and the like of the present invention. be able to.
[0160]
(Thermoreversible recording label and thermoreversible recording member)
The thermoreversible recording label of the present invention includes a surface opposite to an image forming surface of the thermoreversible recording medium of the present invention (when the thermosensitive layer is provided on a support, the thermosensitive layer in the support is used). On the surface opposite to the surface on which is formed), at least one of an adhesive layer and a pressure-sensitive adhesive layer, and other layers appropriately selected as necessary.
[0161]
The shape, structure, size, and the like of the adhesive layer to the pressure-sensitive adhesive layer are not particularly limited and can be appropriately selected depending on the purpose. For example, the shape includes a sheet shape and a film shape. The structure may be a single-layer structure or a laminated structure, and the size may be larger or smaller than the heat-sensitive layer.
The material of the adhesive layer to the pressure-sensitive adhesive layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a urea resin, a melamine resin, a phenol resin, an epoxy resin, a vinyl acetate resin, and acetic acid. Vinyl-acrylic copolymer, ethylene-vinyl acetate copolymer, acrylic resin, polyvinyl ether resin, vinyl chloride-vinyl acetate copolymer, polystyrene resin, polyester resin, polyurethane resin, polyamide resin Chlorinated polyolefin-based resin, polyvinyl butyral-based resin, acrylate-based copolymer, methacrylate-based copolymer, natural rubber, cyanoacrylate-based resin, silicone-based resin, and the like. These may be used alone or in combination of two or more, and may be a hot-melt type, a release paper, or a non-release paper type.
[0162]
When the thermoreversible recording label has at least one of the adhesive layer and the pressure-sensitive adhesive layer, the entire or a part of a thick substrate such as a vinyl chloride card with a magnetic stripe where application of the heat-sensitive layer is difficult. In this case, a part of information magnetically stored can be displayed.
The thermoreversible recording label can be a substitute for a display label on a disk cartridge containing a rewritable disk such as a flexible disk (FD), MD, DVD-RAM, or the like.
[0163]
FIG. 5 shows an example in which the thermoreversible recording label 10 of the present invention is affixed on an MD disk cartridge 70. In this case, application to applications such as automatically changing the display content according to the change of the storage content in the MD is possible. In the case of a disk such as a CD-RW that does not use a disk cartridge, the thermoreversible recording label of the present invention may be directly attached to the disk.
FIG. 6 shows an example in which the thermoreversible recording label 10 of the present invention is attached on a CD-RW 71. In this case, the thermoreversible recording label can be attached to a write-once disc such as a CR-R instead of a CD-RW, and a part of the storage information added to the CD-R can be replaced and displayed. It is.
[0164]
FIG. 7 shows an example in which the thermoreversible recording label of the present invention is attached to an optical information recording medium (CD-RW) using an AgInSbTe-based phase change storage material. The basic configuration of this CD-RW is such that a first dielectric layer 110, an optical information storage layer 109, a second dielectric layer 108, a reflective heat dissipation layer 107, and an intermediate layer 106 are formed on a base 111 having a guide groove. The hard coat layer 112 is provided on the back surface of the base 111 in this order. On the intermediate layer 106 of the CD-RW, the thermoreversible recording label 10 of the present invention is attached. The thermoreversible recording label 10 includes an adhesive layer or a pressure-sensitive adhesive layer 105, a support 104, a light reflection layer 103, a reversible thermosensitive layer 102, and a protective layer 101 in this order. Note that the dielectric layer need not always be provided on both sides of the heat-sensitive layer. However, when the base is made of a material having low heat resistance such as a polycarbonate resin, it is desirable to provide the first dielectric layer 110.
[0165]
FIG. 8 shows an example in which the thermoreversible recording label 10 of the present invention is affixed on a video cassette 72. In this case, the present invention can be applied to applications such as automatically changing display contents in accordance with a change in storage contents in the video tape cassette.
[0166]
As a method of providing the thermoreversible recording function on a card, a disc, a disc cartridge, and a tape cassette, in addition to the method of applying the thermoreversible recording label, a method of directly applying the thermosensitive layer on them, A method in which the heat-sensitive layer is formed on the support, and the heat-sensitive layer is transferred onto the card, the disk, the disk cartridge, and the tape cassette. In the case of the method of transferring the heat-sensitive layer, the adhesive layer or the pressure-sensitive adhesive layer such as a hot-melt type may be provided on the heat-sensitive layer. When the thermoreversible recording label is affixed on a rigid object such as the card, the disk, the disk cartridge and the tape cassette, or when the heat-sensitive layer is provided, the contact with the thermal head is improved. In order to form an image uniformly, it is preferable to provide a layer or sheet which is elastic and serves as a cushion, between the rigid substrate and the label or the heat-sensitive layer.
[0167]
The thermoreversible recording medium of the present invention is, for example, as shown in FIG. 9A, a film in which a reversible thermosensitive layer 13 and a protective layer 14 are provided on a support 11, and as shown in FIG. A film comprising an aluminum reflective layer 12, a reversible thermosensitive layer 13, and a protective layer 14 provided thereon. As shown in FIG. 9C, on a support 11, an aluminum reflective layer 12, a reversible thermosensitive layer 13, and a protective layer are provided. 14, a film in which the magnetic thermosensitive layer 16 is provided on the back surface of the support 11, and the like.
The film (thermo-reversible recording medium) of each of these embodiments can be used, for example, as a form processed into a thermo-reversible recording card 21 having a print display unit 23 as shown in FIG. 10A. As shown in FIG. 10B, a magnetic recording section 24 is formed on the back side of the card.
[0168]
In addition, the thermoreversible recording member (card) shown in FIG. 11A is formed by processing a film in which an aluminum reflective layer, a reversible thermosensitive layer, and a protective layer are provided on a support into a card shape, and a recess 25 for accommodating an IC chip. And processed into a card shape. In FIG. 11A, a rewritable recording section 26 is label-processed on a card-like thermoreversible recording medium, and a recess 25 for embedding an IC chip is formed at a predetermined position on the back side of the cart. As shown in FIG. 11B, the wafer 231 is assembled and fixed in the recess 25. On the wafer 231, an integrated circuit 233 is provided on a wafer substrate 232, and a plurality of contact terminals 234 electrically connected to the integrated circuit 233 are provided on the wafer substrate 232. The contact terminals 234 are exposed on the back surface side of the wafer substrate 232, and are configured so that a dedicated printer (reader / writer) can read and rewrite predetermined information by electrically contacting the contact terminals 234. I have.
[0169]
Next, the function of the thermoreversible recording card will be described with reference to FIG. FIG. 12A is a schematic configuration block diagram illustrating the integrated circuit 233. FIG. 12B is a configuration block diagram illustrating an example of data stored in the RAM. The integrated circuit 233 includes, for example, an LSI. The integrated circuit 233 includes a CPU 235 capable of executing a control operation in a predetermined procedure, a ROM 236 storing operation program data of the CPU 235, and writing and reading of necessary data. A readable RAM 237 is included. Further, the integrated circuit 233 receives an input signal, provides input data to the CPU 235, and receives an output signal from the CPU 235 and outputs the input / output interface 238, and a power-on reset circuit (not shown). It includes a clock generation circuit, a pulse division circuit (interrupt pulse generation circuit), and an address decoder circuit.
The CPU 235 can execute the operation of the interrupt control routine according to the interrupt pulse periodically given from the pulse divider circuit. The address decode circuit decodes the address data from the CPU 235 and supplies signals to the ROM 236, the RAM 237, and the input / output interface 238, respectively. A plurality of (eight in FIG. 12) contact terminals 234 are connected to the input / output interface 238, and predetermined data from the dedicated printer (reader / writer) is transmitted from the contact terminals 234 via the input / output interface 238. It is input to the CPU 235. The CPU 235 performs each operation in response to the input signal and according to the program data stored in the ROM 236, and outputs predetermined data and signals to the sheet reader / writer via the input / output interface 238.
[0170]
As shown in FIG. 12B, the RAM 237 includes a plurality of storage areas 239a to 239g. For example, a sheet number is stored in the area 239a. For example, the storage area 239b stores ID data such as the name, affiliation, and telephone number of the sheet manager. For example, the storage area 239c stores information on the remaining margin or handling that can be used by the user. For example, the storage area 239d, the storage area 239e, the storage area 239f, and the storage area 239g store information related to a previous manager and a previous user.
[0171]
At least one of the thermoreversible recording label and the thermoreversible recording member of the present invention is not particularly limited, and can be subjected to image processing by various image processing methods and image processing apparatuses. It is possible to suitably form and erase images using the apparatus.
[0172]
(Image processing method and image processing device)
The image processing apparatus of the present invention includes at least one of an image forming unit and an image erasing unit, and further includes other units appropriately selected as needed, for example, a conveying unit and a control unit.
The image processing method of the present invention performs at least one of image formation and erasing by heating the thermoreversible recording medium of the present invention, and other steps appropriately selected as necessary, for example, a transporting step, It has a control step and the like.
[0173]
The image processing method of the present invention can be suitably performed by the image processing apparatus of the present invention, and at least one of image formation and image erasing by heating the thermoreversible recording medium of the present invention is performed by the image forming method. And the other steps can be performed by the other means.
[0174]
-Image forming means and image erasing means-
The image forming unit is a unit that forms an image by heating the thermoreversible recording medium of the present invention. Further, the image erasing means is means for erasing an image by heating the thermoreversible recording medium of the present invention.
The image forming unit is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a thermal head and a laser. These may be used alone or in combination of two or more.
The image erasing means is means for erasing an image by heating the thermoreversible recording medium of the present invention, and includes, for example, a hot stamp, a ceramic heater, a heat roller, hot air, a thermal head, a laser, and the like. . Of these, ceramic heaters are preferred. By using the ceramic heater, the device can be reduced in size, a stable erased state can be obtained, and an image with good contrast can be obtained. The set temperature of the ceramic heater is not particularly limited and can be appropriately selected depending on the purpose. For example, 110 ° C. or higher is preferable, 112 ° C. or higher is more preferable, and 115 ° C. or higher is particularly preferable.
[0175]
By using the thermal head, the size can be further reduced, the power consumption can be reduced, and a hand-held device driven by a battery can be realized. Further, one thermal head can be used for both recording and erasing of the image, and in this case, further downsizing can be achieved. When recording and erasing are performed by one thermal head, a new image may be recorded again after erasing all the previous images, or the previous image may be erased at once by changing the energy for each image, and a new image may be recorded. An overwrite method of recording an image is also possible. In the overwriting method, the time required for recording and erasing the image is reduced, and the recording speed is increased.
When a thermoreversible recording member (card) having the heat-sensitive layer and the information storage unit is used, the device includes a unit for reading and rewriting the storage unit of the information storage unit.
[0176]
The transport unit is not particularly limited as long as it has a function of sequentially transporting the thermoreversible recording medium, and can be appropriately selected depending on the purpose. For example, a transport belt, a transport roller, a transport belt and a transport roller And the like.
[0177]
The control means is not particularly limited as long as it has a function of controlling each step, and can control each step, and examples thereof include devices such as a sequencer and a computer.
[0178]
One mode of implementing the image processing method of the present invention by the image processing apparatus of the present invention will be described with reference to FIG. The image processing apparatus shown in FIG. 13 includes a thermal head 53 as the heating processing means, a ceramic heater 38, a magnetic head 34, and transport rollers 31, 40, and 47.
As shown in FIG. 13A, in this image processing apparatus, first, information stored in a magnetic thermosensitive layer of a recording medium is read by a magnetic head. Next, the image recorded on the reversible thermosensitive layer is heated and erased by a ceramic heater. Further, based on the information read by the magnetic head, processed new information is recorded on the reversible thermosensitive layer by the thermal head. Thereafter, the information of the magnetic thermosensitive layer is also rewritten with new information.
In the image processing apparatus shown in FIG. 13A, the thermoreversible recording medium 1 provided with a magnetic thermosensitive layer on the opposite side of the thermosensitive layer is conveyed along a conveying path shown by a reciprocating arrow, or along the conveying path. It is transported in the device in the reverse direction. The thermoreversible recording medium 1 is magnetically recorded or erased on the magnetic thermosensitive layer between the magnetic head 34 and the conveying roller 31, and is heated between the ceramic heater 38 and the conveying roller 40 for image erasing. An image is formed between the images. Then, it is carried out of the apparatus. As described above, the set temperature of the ceramic heater 38 is preferably 110 ° C. or higher, more preferably 112 ° C. or higher, and particularly preferably 115 ° C. or higher. However, the rewriting of the magnetic recording may be performed before or after the image is erased by the ceramic heater. Further, if desired, after passing between the ceramic heater 38 and the transport roller 40 or after passing between the thermal head 53 and the transport roller 47, the sheet is transported in the reverse direction on the transport path. The heat treatment by the ceramic heater 38 and the printing process by the thermal head 53 can be performed again.
[0179]
In the image processing apparatus of FIG. 13B, the thermoreversible recording medium 1 inserted from the entrance 30 advances along the transport path 50 indicated by a dashed line, or travels in the apparatus in the reverse direction along the transport path 50. Proceed to. The thermoreversible recording medium 1 inserted from the entrance 30 is conveyed in the recording apparatus by the conveying rollers 31 and the guide rollers 32. When it reaches a predetermined position on the transport path 50, its presence is recognized by the sensor 33 via the control means 34c, magnetic recording or erasing is performed on the magnetic thermosensitive layer between the magnetic head 34 and the platen roller 35, and the guide roller 36 and Between the conveyance roller 37, between the guide roller 39 and the conveyance roller 40, between the ceramic heater 38 and the platen roller 44, which operate by recognizing the presence thereof by the sensor 43 via the ceramic heater control means 38c. Is heated in order to erase the image, is conveyed in the conveyance path 50 by the conveyance rollers 45, 46 and 47, and operates by recognizing the presence thereof at a predetermined position via the thermal head control means 53c by the sensor 51. An image is formed between the head 53 and the platen roller 52, and the conveyance roller 59 It is unloaded outside the apparatus through the outlet 61 by Dorora 60. Here, the set temperature of the ceramic heater 38 is not particularly limited and can be appropriately selected depending on the purpose. As described above, 110 ° C. or higher is preferable, 112 ° C. or higher is more preferable, and 115 ° C. or higher is preferable. Particularly preferred.
[0180]
If desired, the transport belt switching means 55a is switched to the transport path 56b, and the transport belt 58 is moved in the reverse direction by the operation of the limit switch 57a which is input by pressing the thermoreversible recording medium 1. Is again heat-treated between the thermal head 53 and the platen roller 52, and then transported in the forward direction via the transport path 49b, the limit switch 57b, and the transport belt 48, which are connected by switching the transport path switching means 55b, and from the transport path 56a. The sheet can be carried out of the apparatus via the outlet 61 by the conveying roller 59 and the guide roller 60. Further, such a branched transport path and transport switching means may be provided on both sides of the ceramic heater 38. In that case, it is desirable to provide the sensor 43a between the platen roller 44 and the transport roller 45.
[0181]
According to the image processing apparatus and the image processing method of the present invention, high-speed processing can be performed in a short time, images can be sufficiently formed and erased even with a short heating time using a thermal head or the like. In this case, the image is excellent in erasability and a high-contrast image can be formed.
[0182]
【Example】
Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.
[0183]
(Synthesis example 1)
-Synthesis of acrylic resin (A1)-
132 parts by mass of styrene, 297 parts by mass of methyl methacrylate, 54 parts by mass of 2-ethylhexyl acrylate, 108 parts by mass of 4-hydroxybutyl acrylate, and 9 parts by mass of methacrylic acid were mixed to prepare a monomer mixture.
In a 2 liter four-necked flask, 360 parts by mass of butyl acetate as a solvent and 540 parts by mass of the monomer mixture were charged. 6.6 parts by mass of Kayaester O (manufactured by Kayaku Akzo) as an initiator was added to the remaining monomer mixture to prepare a monomer mixture for dropping. After maintaining the temperature in the flask at 120 ° C., the monomer mixture for dropping was dropped over 4 hours, and after the dropping, 30 parts by mass of butyl acetate was charged. The temperature in the flask was kept at 120 ° C. for 1 hour, and an initiator mixture consisting of 1.2 parts by mass of Kayaester O and 30 parts by mass of butyl acetate as an additional initiator was added all at once every three hours at once. Further, after maintaining the temperature in the flask at 120 ° C. for 1 hour, when the temperature in the flask was cooled to 80 ° C. or less, 360 parts by mass of methyl ethyl ketone (MEK) was charged and cooled, and the acrylic resin (A1) of Synthesis Example 1 was cooled. Was synthesized. In addition, the obtained acrylic resin (A1) was canned and stored.
The characteristic values of the obtained acrylic resin (A1) are as follows: viscosity (bubble viscometer) is -J, heating residue is 42.1% by mass, acid value is 4.1 mgKOH / g, hydroxyl value is 70, weight average molecular weight. Was 39,000. The glass transition temperature (Tg) obtained by calculation of the acrylic resin was 45 ° C., and the refractive index obtained by calculation was 1.5115.
[0184]
(Example 1)
-Production of thermoreversible recording medium-
First, on the PET film side of a magnetic material (Dynipp Ink Kogyo Co., Ltd. (Memory Dick, DS-1711-1040: a transparent heat-sensitive layer and a self-cleaning layer coated on a transparent PET film having a thickness of 188 μm)) Aluminum (Al) was vacuum-deposited to a thickness of about 400 ° to provide a light reflecting layer. For an adhesive layer comprising 10 parts by mass of a vinyl chloride-vinyl acetate-phosphate ester copolymer (manufactured by Denki Kagaku Kogyo Co., Denka Vinyl # 1000P), 45 parts by mass of methyl ethyl ketone, and 45 parts by mass of toluene on the light reflecting layer The coating solution was applied, dried by heating, and an adhesive layer was provided so as to have a thickness of about 0.5 μm. Next, on the adhesive layer, 5 parts by mass of stearyl stearate (manufactured by NOF CORPORATION, M9676), 5 parts by mass of eicosane diacid (manufactured by Okamura Oil Co., Ltd., SL-20-90), and the acrylic resin (A1 ) 27 parts by mass, an isocyanate compound (manufactured by Nippon Polyurethane, Coronate 2298-90T) 3 parts by mass, a coating solution for a heat-sensitive layer consisting of 40 parts by mass of xylene and 160 parts by mass of tetrahydrofuran, and dried by heating at 130 ° C. for 3 minutes. Then, a heat-sensitive layer was provided so as to have a thickness of about 10 μm, and was cured by heating at 60 ° C. for 48 hours. Next, on the heat-sensitive layer, a protective layer composed of 10 parts by mass of a 75% by mass butyl acetate solution of a urethane acrylate ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals, UNIDEC C7-157) and 10 parts by mass of isopropyl alcohol The coating solution was applied with a wire bar, dried by heating, and then cured with an ultraviolet lamp of 80 W / cm to provide a protective layer having a thickness of about 2 μm.
Thus, a thermoreversible recording medium of Example 1 was produced.
[0185]
(Synthesis example 2)
-Synthesis of acrylic resin (A2)-
In Synthesis Example 1, the monomer mixture was a monomer mixture of 132 parts by mass of styrene, 309 parts by mass of methyl methacrylate, 42 parts by mass of 2-ethylhexyl acrylate, 108 parts by mass of 4-hydroxybutyl acrylate, and 9 parts by mass of methacrylic acid. An acrylic resin (A2) of Synthesis Example 2 was synthesized in the same manner as in Synthesis Example 1 except that the amount was changed to 600 parts by mass.
The solution characteristic values of the obtained acrylic resin (A2) were as follows: viscosity (bubble viscometer) -G, heating residue: 42.1 mass%, acid value: 4.1 mgKOH / g, hydroxyl value: 70, weight average The molecular weight was 40,000. The glass transition temperature (Tg) of the acrylic resin (A2) obtained by calculation was 50 ° C., and the calculated refractive index was 1.5115.
[0186]
(Example 2)
-Production of thermoreversible recording medium-
The thermoreversible recording medium of Example 2 was prepared in the same manner as in Example 1 except that the acrylic resin (A1) of Synthesis Example 1 was replaced with the acrylic copolymer (A2) of Synthesis Example 2. Produced.
[0187]
(Synthesis example 3)
-Synthesis of acrylic resin (A3)-
In Synthesis Example 1, 150 parts by mass of styrene, 123 parts by mass of methyl methacrylate, 132 parts by mass of benzyl methacrylate, 78 parts by mass of 2-ethylhexyl acrylate, 108 parts by mass of 4-hydroxybutyl acrylate, 108 parts by mass of methacrylic acid An acrylic resin (A3) of Synthesis Example 3 was synthesized in the same manner as in Synthesis Example 1 except that the monomer mixture was changed to 600 parts by mass of 9 parts by mass.
The solution characteristic values of the obtained acrylic resin (A3) were such that the viscosity (bubble viscometer) was -D, the heating residue was 41.5% by mass, the acid value was 4.5 mgKOH / g, the hydroxyl value was 70, and the weight average. The molecular weight was 38,000. The glass transition temperature (Tg) obtained by calculation of the acrylic resin was 30 ° C., and the refractive index obtained by calculation was 1.5308.
[0188]
(Example 3)
-Production of thermoreversible recording medium-
In Example 1, the heat of Example 3 was changed in the same manner as in Example 1 except that the acrylic resin (A1) was replaced with the acrylic resin (A3) and the isocyanate compound was replaced with Coronate HL (manufactured by Nippon Polyurethane). A reversible recording medium was manufactured.
[0189]
(Synthesis example 4)
-Synthesis of acrylic resin (A4)-
In Synthesis Example 1, 120 parts by mass of styrene, 153 parts by mass of methyl methacrylate, 180 parts by mass of benzyl methacrylate, 30 parts by mass of 2-ethylhexyl acrylate, 108 parts by mass of 4-hydroxybutyl acrylate, and methacrylic acid. An acrylic resin (A4) of Synthesis Example 4 was synthesized in the same manner as in Synthesis Example 1 except that the monomer mixture was changed to 600 parts by mass of 9 parts by mass of luic acid.
The solution characteristic values of the obtained acrylic resin (A4) are as follows: viscosity (bubble viscometer) is -R, heating residue is 50.9 mass%, acid value is 5.1 mgKOH / g, Tg is 40 ° C, and hydroxyl value is Was 70 and the weight average molecular weight was 41,000. The refractive index of the acrylic resin obtained by calculation was 1.532.
[0190]
(Example 4)
-Production of thermoreversible recording medium-
A thermoreversible recording medium of Example 4 was produced in the same manner as in Example 1 except that the acrylic resin (A1) was replaced with the acrylic resin (A4).
[0191]
(Synthesis example 5)
-Synthesis example of acrylic resin (A5)-
In Synthesis Example 1, the monomer mixture was a monomer composed of 125 parts by mass of styrene, 291 parts by mass of methyl methacrylate, 67 parts by mass of 2-ethylhexyl acrylate, 108 parts by mass of 4-hydroxybutyl acrylate, and 9 parts by mass of methacrylic acid. An acrylic resin (A5) of Synthesis Example 5 was synthesized in the same manner as in Synthesis Example 1 except that the mixture was changed to 600 parts by mass.
The solution characteristic values of the obtained acrylic copolymer (A5) are as follows: viscosity (bubble viscometer) is -C, heating residue is 40.4 mass%, acid value is 4.2 gKOH / g, Tg is 40 ° C, The hydroxyl value was 70 and the weight average molecular weight was 37,800. The refractive index obtained by calculation of the acrylic resin was 1.5113.
[0192]
(Example 5)
-Production of thermoreversible recording medium-
A thermoreversible recording medium of Example 5 was produced in the same manner as in Example 1 except that the acrylic resin (A1) was changed to the acrylic resin (A5).
[0193]
(Synthesis example 6)
-Synthesis of acrylic resin (A6)-
In Synthesis Example 1, the monomer mixture was obtained by mixing a monomer mixture 600 with styrene 100 parts by mass, methyl methacrylate 290 parts by mass, butyl acrylate 93 parts by mass, 4-hydroxybutyl acrylate 108 parts by mass, and methacrylic acid 9 parts by mass. An acrylic resin (A6) of Synthesis Example 6 was synthesized in the same manner as in Synthesis Example 1 except that the amount was changed to parts by mass.
The solution characteristics of the obtained acrylic resin (A6) are as follows: viscosity (bubble viscometer) is -D, heating residue is 40.2 mass%, acid value is 4.1 mgKOH / g, Tg is 40 ° C, and weight average molecular weight. Was 42,000. The refractive index obtained by calculation of the acrylic resin was 1.5116.
[0194]
(Example 6)
-Production of thermoreversible recording medium-
In Example 1, the heat of Example 6 was changed in the same manner as in Example 1 except that the acrylic resin (A1) was replaced with the acrylic resin (A6) and the isocyanate compound was replaced with Coronate HL (manufactured by Nippon Polyurethane). A reversible recording medium was manufactured.
[0195]
(Synthesis example 7)
-Synthesis of acrylic resin (A7)-
In Synthesis Example 1, 210 parts by mass of styrene, 229.2 parts by mass of methyl methacrylate, 90 parts by mass of 2-ethylhexyl acrylate, 58.8 parts by mass of 4-hydroxybutyl acrylate, and 12 parts by mass of methacrylic acid in Synthesis Example 1. The acrylic resin (A7) of Synthesis Example 7 was synthesized in the same manner as in Synthesis Example 1 except that the monomer mixture was changed to parts.
The solution characteristic value of the obtained acrylic resin (A7) was such that the viscosity (bubble viscometer) was -D, the heating residue was 40% by mass, the acid value was 4.3 mgKOH / g, the glass transition temperature (Tg) was 50 ° C, The weight average molecular weight was 40,000. The refractive index obtained by calculation of the acrylic resin was 1.5257.
[0196]
(Example 7)
-Production of thermoreversible recording medium-
First, a magnetic material (Dainippon Ink Kogyo Co., Ltd. (Memory Dick, DS-1711-1040: a transparent 188 μm thick PET film coated with a magnetic thermosensitive layer and a self-cleaning layer)) was coated on the PET film side. Aluminum (Al) was vacuum deposited to a thickness of 400 ° to provide a light reflecting layer. Next, on the light reflection layer, 10 parts by mass of a vinyl chloride-vinyl acetate-phosphate ester copolymer (manufactured by Denki Kagaku Kogyo Co., Ltd., Denka Vinyl # 1000P), 45 parts by mass of methyl ethyl ketone, and 45 parts by mass of toluene An adhesive layer coating solution was applied and dried by heating to provide an adhesive layer having a thickness of about 0.5 μm. Next, with respect to 502 parts by mass of the acrylic resin (A7) of Synthesis Example 7, 63 parts by mass of stearyl stearate (SS96, manufactured by Miyoshi Oil & Fats Co., Ltd.) were added, and 8 parts by mass of an isocyanate compound represented by the following structural formula (A) Parts, 9 parts by mass of an isocyanate compound represented by the following structural formula (B), and 220 parts by mass of methyl ethyl ketone were placed in a glass bottle, and ceramic beads having a diameter of about 2 mm were put therein and dispersed using a paint shaker (manufactured by Asada Iron Works) for 35 hours. Liquid A was prepared.
[0197]
Embedded image

[0198]
Next, 209 parts by mass of methyl ethyl ketone, 35 parts by mass of an isocyanate compound (E-402-90T; manufactured by Asahi Chemical), 115 parts by mass of o-xylene, and a 1% by mass solution of a leveling agent (ST102PA MEK) were added to 400 parts by mass of the dispersion A. 4) A dispersion solution consisting of 4 parts by mass was applied on the adhesive layer, and was heated and dried at 125 ° C. for 1 minute to form a heat-sensitive layer having a thickness of about 11 μm, and then heated at 50 ° C. for 48 hours. And cured. Next, a protective layer was formed on the heat-sensitive layer in the same manner as in Example 1.
Thus, a thermoreversible recording medium of Example 7 was manufactured.
[0199]
(Example 8)
-Production of thermoreversible recording medium-
In Example 7, the thermoreversible recording of Example 8 was carried out in the same manner as in Example 7, except that the isocyanate compounds represented by the structural formulas (A) and (B) were not added to the coating solution for the thermosensitive layer. A medium was prepared.
[0200]
(Comparative Example 1)
-Production of thermoreversible recording medium-
First, about 400 mm of a magnetic material (Dainippon Ink Kogyo Co., Ltd. (Memory Dick, DS-1711-1040: a transparent 188 μm thick PET film coated with a magnetic thermosensitive layer and a self-cleaning layer)) was applied to the PET film side. The light reflecting layer was provided by vacuum-depositing aluminum (Al) to a thickness of. Next, on the light reflection layer, 10 parts by mass of a vinyl chloride-vinyl acetate-phosphate ester copolymer (manufactured by Denki Kagaku Kogyo Co., Ltd., Denka Vinyl # 1000P), 45 parts by mass of methyl ethyl ketone, and 45 parts by mass of toluene An adhesive layer coating solution was applied and dried by heating to provide an adhesive layer having a thickness of about 0.5 μm. Next, on the adhesive layer, 120 parts by mass of a vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Co., Ltd., Solvene C, vinyl chloride / vinyl acetate = 87/13 (molar ratio)), and 40 parts by mass of hexadecyl stearate , 10 parts by weight of dodecaneic acid, 10 parts by weight of stearone (18-pentatriacontanone), and 945 parts by weight of THF, and a heat-sensitive layer coating solution was applied thereto, and was dried by heating at 120 ° C. for 2 minutes to a thickness of about 10 μm. After the heat-sensitive layer was provided as described above, the coating was heated at 60 ° C. for 48 hours to be cured. Next, on the heat-sensitive layer, a protective layer composed of 10 parts by mass of a 75% by mass butyl acetate solution of a urethane acrylate ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals, UNIDEC C7-157) and 10 parts by mass of isopropyl alcohol The coating solution was applied with a wire bar, dried by heating, and then cured with an ultraviolet lamp of 80 W / cm, and a protective layer was provided to a thickness of about 2 μm.
Thus, a thermoreversible recording medium of Comparative Example 1 was produced.
[0201]
(Comparative Example 2)
-Production of thermoreversible recording medium-
In Comparative Example 1, 80 parts by mass of a vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Co., Ltd., Solvene C, vinyl chloride / vinyl acetate = 87/13 (molar ratio)), dihexa A thermoreversible recording medium of Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that a heat-sensitive layer coating solution composed of 28 parts by mass of decylthioether, 12 parts by mass of dodecanenilic acid, and 630 parts by mass of THF was used.
[0202]
(Comparative Example 3)
-Production of thermoreversible recording medium-
In Comparative Example 1, VMCH (a copolymer having a balance of 85 to 87% by mass of vinyl chloride, 0.7 to 1% by mass of MA (maleic acid), and a balance of vinyl acetate) of 50 (VMC) was formed on the adhesive layer. Parts by mass, 25 parts by mass of dodecanenic acid, 60 parts by mass of stearyl behenate, 20 parts by mass of 1-9 nonanediol acrylate, 120 parts by mass of low Tg acrylic resin (manufactured by Toagosei Chemicals, S2040, solid content 30% by mass), Irgacure 184 (a curing agent manufactured by Ciba-Geigy), 10 parts by mass of a dimethylpolysiloxane-polyoxyalkylene copolymer leveling agent (ST102PA manufactured by Toray Dow Corning Silicon), and a coating solution for a heat-sensitive layer consisting of 962 parts by mass of THF. After applying and drying by heating at 130 ° C. for 1 minute, UV irradiation of 80 W / cm × 2 lamps is performed to obtain a thickness of about 10 μm. A thermoreversible recording medium of Comparative Example 3 was produced in the same manner as in Comparative Example 1, except that the heat-sensitive layer was provided so as to obtain a cured layer, and then heated and cured at 60 ° C. for 48 hours.
[0203]
(Comparative Example 4)
-Production of thermoreversible recording medium-
In Comparative Example 1, as a heat-sensitive layer coating solution, 120 parts by mass of VYHH (manufactured by UCC, 85 to 87% by mass of vinyl chloride, a copolymer having a balance of vinyl acetate), 50 parts by mass of behenyl behenate, and 10 parts of dodecanenilic acid Parts by mass, 240 parts by mass of low Tg acrylic resin (manufactured by Toagosei Chemical Co., S2040, solid content: 30% by mass), 10 parts by mass of isocyanate compound (manufactured by Nippon Polyurethane, Coronate L), dimethylpolysiloxane-polyoxyalkylene copolymer The thermoreversible recording medium of Comparative Example 4 was prepared in the same manner as in Comparative Example 1 except that the coating solution for the heat-sensitive layer was composed of 10 parts by mass of a leveling agent (manufactured by Toray Dow Corning Silicon, ST102PA) and 1183 parts by mass of THF. did.
[0204]
(Comparative Example 5)
-Production of thermoreversible recording medium-
First, HOOC (CH) was added to 500 parts by mass of a 15 mass% solids solution of a vinyl chloride copolymer (MR110, manufactured by Zeon Corporation) in THF. ₂ ) ₅ NHCO (CH ₂ ) CONH (CH ₂ ) ₅ COOH _Fifteen Was added, and ceramic beads having a diameter of about 2 mm were put in a glass bottle and dispersed using a paint shaker (manufactured by Asada Iron Works) for 48 hours to prepare Dispersion A.
110 parts by mass of behenic acid (manufactured by Miyoshi Oil & Fat Co., Ltd., behenic acid 95), 25 parts by mass of eicosanoic acid (manufactured by Okamura Oil Co., Ltd., SL-20-90), 300 parts by mass of vinyl chloride copolymer (manufactured by Zeon Corporation, MR110) Parts, THF 170 parts by mass and o-xylene 60 parts by mass were mixed by a conventional method to prepare Dispersion B.
Next, 8 parts by mass of the dispersion A, 270 parts by mass of the dispersion B, and 60 parts by mass of an isocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd., 2298-90T) were mixed to prepare a coating solution for a heat-sensitive layer.
Next, a thermoreversible recording medium of Comparative Example 5 was produced in the same manner as in Comparative Example 1, except that the coating solution for a heat-sensitive layer was used.
[0205]
(Comparative Example 6)
-Production of thermoreversible recording medium-
In Comparative Example 1, 4.75 parts by mass of dodecyl 1,18-octadecadicarboxylate (manufactured by Miyoshi Oil & Fats Co.) and 5.25 parts of eicosane diacid (manufactured by Okamura Oil Co., Ltd., SL-20-99) on the adhesive layer. 28 parts by mass, 28 parts by mass of a vinyl chloride-vinyl acetate copolymer (manufactured by Kaneka Chemical Co., Ltd .; M2018, 80% by mass of vinyl chloride, 20% by mass of vinyl acetate, average degree of polymerization = 1800), a reactive polymer (Shin-Nakamura Chemical) 4.7 parts by mass of NK Polymer B-3015H manufactured by Kogyo Co., Ltd., 215.5 parts by mass of THF, 24 parts by mass of amyl alcohol, and a dibutyltin laurate-based stabilizer (Stann SCAT-1 manufactured by Sankyoki Gosei Co., Ltd.) A coating solution for a heat-sensitive layer consisting of 8 parts by mass was applied and dried by heating to form a heat-sensitive layer (reversible heat-sensitive layer) so as to have a thickness of about 8 μm. Next, for the heat-sensitive layer, an electron beam irradiation was performed by using an area beam type electron beam irradiation device EBC-200-AA2 manufactured by Nissin High Voltage Co., Ltd. as an electron beam irradiation device, adjusting the irradiation dose to 10 Mrad. Then, a thermoreversible recording medium of Comparative Example 6 was produced.
[0206]
(Comparative Example 7)
-Production of thermoreversible recording medium-
In Comparative Example 1, 100 parts by mass of an acrylic resin (LR-269, manufactured by Mitsubishi Rayon), 50 parts by mass of tetraethylene glycol diacrylate, and 2 parts by mass of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Geigy) on the adhesive layer. , A polyester plasticizer (manufactured by DIC, P-29), 25 parts by mass, 40 parts by mass of stearyl stearate, 8 parts by mass of eicosanoic acid, and 180 parts by mass of tetrahydrofuran were coated with a coating solution for a heat-sensitive layer. Comparative Example 7 was carried out in the same manner as in Comparative Example 1 except that UV irradiation was performed under the conditions of 120 W / cm · 10 m / min, and a heat-sensitive layer was provided so as to have a thickness of about 10 μm. Was prepared.
[0207]
(Example 9)
-Production of thermoreversible recording label-
An acrylic pressure-sensitive adhesive layer having a thickness of about 5 μm was provided on the surface of the support of the thermoreversible recording medium prepared in Example 4 on which the heat-sensitive layer surface was not provided (back surface).
Thus, a thermoreversible recording label of Example 10 was produced.
[0208]
(Example 10)
-Preparation and evaluation of thermoreversible recording member-
A printing apparatus having a printing with UV ink (manufactured by HAKURI OP Varnish UP2 T & K Toka Co.) on the surface of the thermoreversible recording medium manufactured in Example 9, cutting out this into a card shape and having a recording and erasing means (thermal head). Was used to adjust the recording energy of the thermal head in accordance with the change in the recording energy of the thermoreversible recording medium, and displayed and recorded on the thermosensitive layer, visualized, and recorded and erased. Further, the rewriting of the display record was repeated 50 times, and the recording and erasing were good.
[0209]
(Example 11)
-Preparation and evaluation of thermoreversible recording member-
The thermoreversible recording label produced in Example 9 was stuck on a mini disc (MD) cartridge. Using a recording device having recording and erasing means (thermal head), a part of the information (date, song name, etc.) stored in the MD is adjusted to change the recording energy of the medium with the recording energy of the medium. The temperature was adjusted and displayed and recorded on the thermosensitive layer, visualized, and recorded and erased. Further, the rewriting of the display record was repeated 50 times, and the recording and erasing were good.
[0210]
(Example 12)
-Preparation and evaluation of thermoreversible recording member-
The thermoreversible recording label produced in Example 9 was adhered on a CD-RW to produce an optical information recording medium having a thermoreversible display function. Using this optical information recording medium, a part of information (year, month, day, time, etc.) stored by a CD-RW drive (MP6200S, manufactured by Ricoh Co., Ltd.) is recorded by a recording and erasing means (thermal head). Using a device, the recording energy of the thermal head was adjusted in accordance with the change in the recording temperature of the recording medium, and was displayed and recorded on the thermosensitive layer and visualized. Also, using the CD-RW drive, the information in the storage layer of the optical information recording medium is rewritten, the erasing means is erased by the recording device, the previous recording is erased, and the rewritten information is rewritten by the thermal head to the thermosensitive layer. And recorded. Further, rewriting of this display record was repeated 50 times, and the recording and erasing were good.
[0211]
(Example 13)
-Thermoreversible recording member and evaluation-
The thermoreversible recording label prepared in Example 9 was stuck on a tape cassette. Using a recording device having recording and erasing means (thermal head), a part of the information (date, song name, etc.) stored in the tape cassette is used to change the recording energy of the thermal head to the recording energy of each medium. The display was recorded on the thermosensitive layer, visualized, and recorded and erased. Further, the rewriting of the display record was repeated 50 times, and the recording and erasing were good.
[0212]
Next, with respect to each of the obtained thermoreversible recording media of Examples 1 to 9 and Comparative Examples 1 to 7, erasability, transparency temperature range, glass transition temperature change, ammonia resistance, and repetition were as follows. The durability was measured. The results are shown in Tables 1 and 2.
[0213]
<Erasability>
Using a printing tester manufactured by Yashiro Electric Co., Ltd. as a thermal recording device and KBE-40-8MGK1 manufactured by Kyocera Corporation as a thermal head, forming a cloudy image under the conditions of a pulse width of 2.0 msec and an applied voltage of 11.0 V. went. Immediately thereafter, the printing conditions by the thermal head were set to a line period of 4.2 ms, a pulse width of 2.94 ms, and a printing speed of 29.76 mm / s, and the applied energy was appropriately changed from 0.085 mj / dot to 0.30 mj / dot. To make it transparent. The erase density at each energy was measured with a Macbeth RD-914 densitometer (manufactured by Macbeth) to determine the erasability. Similarly to FIG. 4, the relationship between the erasing density and the erasing energy was graphed to determine the erasable energy width. In addition, the density of the part that was made maximum transparent was defined as the maximum transparent density, and the difference between the maximum transparent density and the background was defined as the initial erasability. The difference between the density and the background at the same site as the initial erasability was defined as the erasure over time. The results of Examples 1 to 6 are shown in FIGS. The results of Example 7 are shown in FIG. The results of Comparative Examples 1 to 6 are shown in FIGS. Table 1 shows the results.
[0214]
<Transparency temperature range>
The clearing temperature range (ΔTw) was measured as follows.
Each thermoreversible recording medium was previously sufficiently turbid. Next, each of the cloudy thermoreversible recording media was heated while changing the temperature, and the temperature at which it became transparent was measured. A thermal gradient tester (HG-100 manufactured by Toyo Seiki Co., Ltd.) was used for heating each thermoreversible recording medium. This thermal gradient tester has five heating blocks, and each block can individually set a temperature, and can control a heating time and a pressure. Under the set conditions, the thermoreversible recording medium can be heated at five different temperatures at a time. Specifically, the heating time is set to 1.0 second, and the pressure at the time of heating is set to about 1.0 kg / cm. ² And The heating temperature was from a low temperature at which the whiteness did not change even when heated, to a temperature at which the whiteness became sufficiently cloudy at equal temperature intervals of 1 to 5 ° C. After heating, the temperature was cooled to room temperature, and the density of the portion heated at each temperature was measured using a Macbeth RD-914 reflection densitometer (manufactured by Macbeth). As shown in FIG. A graph is created in which the set temperature and the vertical axis are the reflection density. The transparency temperature range was determined in the same manner as in FIG. The result of Example 7 is shown in FIG. The results of Comparative Examples 1 to 6 are shown in FIGS. Table 1 shows the results.
[0215]
<Glass transition temperature change>
DSC measurement was performed using a differential thermal layer scanning calorimeter 6200 (manufactured by SII) as the differential thermal layer scanning calorie. The sample of the heat-sensitive layer in each thermoreversible recording medium was peeled off by using diluted hydrofluoric acid applied on the aluminum vapor-deposited layer, and 3 mg to 6 mg of the sample was put into an aluminum cell for DSC measurement and measured. Was. Aluminum oxide was used as a standard substance. The heating rate was 15 ° C./min.
The initial glass transition temperature (Tgi) was measured after a sample put in an aluminum cell for DSC measurement was heated at 130 ° C. for 5 minutes in a thermostat and left at room temperature (23 ° C.) for 30 minutes. The glass transition temperature obtained from the DSC curve at this time was measured. The glass transition temperature with time was measured after heating at 130 ° C. for 5 minutes, sufficiently cooling at room temperature, and then storing in a 35 ° C. atmosphere for one week. The glass transition temperature obtained from the DSC curve at this time was defined as the glass transition temperature over time (Tga).
[0216]
<Ammonia resistance>
-Transparency temperature range test-
For Examples 5 and 7, and Comparative Examples 2 and 5, the transparentizing temperature range of each thermoreversible recording medium before the test and each thermoreversible recording medium after being immersed in an 8% by mass aqueous solution of ammonium carbonate for 48 hours. Was measured by the above-mentioned method for measuring the transparency temperature range, and evaluated according to the following criteria.
〔Evaluation criteria〕
○: No change
×: Large change
-Image density change test-
For Examples 5 and 7, the image density when each thermoreversible recording medium not immersed in the base substance was opaque was used as the initial image, and the thermoreversible recording medium was immersed in an 8% by mass aqueous ammonium carbonate solution, and the immersion time was set. Was changed after 10 minutes, 30 minutes, 1 hour, and 6 hours, and the image density was measured when clouding was performed with the same energy.
[0219]
<Repeat durability>
In Examples 7 and 8, the number of times when the image density evaluation changed by 0.5 or more when printing and erasing were repeated was compared for each thermoreversible recording medium with respect to the repeated durability using a thermal head. The evaluation of repeated printing / erasing up to 500 times was performed.
[0218]
[Table 1]

[0219]
[Table 2]

[0220]
【The invention's effect】
According to the present invention, the conventional problems can be solved, the processing speed is fast, even when heating is performed for a minimum time of milliseconds using a thermal head, the image can be sufficiently erased, and after image formation, A thermoreversible recording medium capable of forming an image excellent in storability, contrast, visibility and the like even when left at a high temperature for a long time while maintaining sufficient erasability without changing the erasing energy; Using a medium, thermoreversible recording labels suitable as various labels, cards, etc., thermoreversible recording members suitable as discs, disk cartridges, tape cassettes, etc., images with high processing speed, excellent contrast, visibility, etc. An image processing apparatus and an image processing method that can be formed can be provided.
[Brief description of the drawings]
FIG. 1 is a graph showing an example of a relationship between a temperature and a change in transparency in a thermoreversible recording medium of the present invention.
FIG. 2 is a graph showing an example of a relationship between a temperature and a change in transparency in the thermoreversible recording medium of the present invention.
FIG. 3 is a graph showing an example of the relationship between the application of energy, the erase energy width, and the reflection density in the thermoreversible recording medium of the present invention.
FIG. 4 is a graph showing enthalpy relaxation measurement by DSC measurement.
FIG. 5 is a schematic diagram showing an example of a state in which the thermoreversible recording medium label of the present invention is attached to an MD disk cartridge.
FIG. 6 is a schematic view showing an example of a state in which the thermoreversible recording label of the present invention is stuck on a CD-RW.
FIG. 7 is a schematic cross-sectional view showing an example of a state in which the thermoreversible recording label of the present invention is stuck on an optical information recording medium (CD-RW).
FIG. 8 is a schematic diagram showing an example of a state in which the thermoreversible recording label of the present invention is attached to a video cassette.
FIG. 9A is a schematic view showing a film in which a heat-sensitive layer and a protective layer are provided on a support. FIG. 9B is a schematic view showing a film in which a reflective layer, a heat-sensitive layer, and a protective layer are provided on a support. FIG. 9C is a schematic view showing a film in which a reflective layer, a thermosensitive layer, and a protective layer are provided on a support, and a magnetic thermosensitive layer is provided on the back surface of the support.
FIG. 10A is a schematic diagram of a front surface side of an example of a thermoreversible recording medium of the present invention processed into a card shape. FIG. 10B is a schematic view of the back surface side of FIG. 10A.
FIG. 11A is a schematic view of an example in which an example of the thermoreversible recording medium of the present invention is processed into another card shape. FIG. 11B is a schematic diagram of an IC chip embedded in the IC chip recess of FIG. 11A.
FIG. 12A is a schematic configuration block diagram illustrating an integrated circuit. FIG. 12B is a schematic diagram showing that the RAM includes a plurality of storage areas.
FIG. 13A is a schematic diagram of an image processing apparatus in which a surface image is erased by a ceramic heater and an image is formed by a thermal head. FIG. 13B is a schematic diagram illustrating an example of the image processing apparatus of the present invention.
FIG. 14 is a graph showing a relationship between a temperature and a change in transparency in Example 1.
FIG. 15 is a graph showing a relationship between a temperature and a change in transparency in Example 2.
FIG. 16 is a graph showing a relationship between a temperature and a change in transparency in Example 3.
FIG. 17 is a graph showing a relationship between a temperature and a change in transparency in Example 4.
FIG. 18 is a graph showing a relationship between a temperature and a change in transparency in Example 5.
FIG. 19 is a graph showing a relationship between a temperature and a change in transparency in Example 6.
FIG. 20 is a graph showing a relationship between a temperature and a change in transparency in Example 7.
FIG. 21 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 1.
FIG. 22 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 2.
FIG. 23 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 3.
FIG. 24 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 4.
FIG. 25 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 5.
FIG. 26 is a graph showing a relationship between a temperature and a change in transparency in Comparative Example 6.
FIG. 27 is a graph showing the relationship between reflection density and temperature in Example 7.
FIG. 28 is a graph showing the relationship between the reflection density and the temperature in Comparative Example 1.
FIG. 29 is a graph showing the relationship between the reflection density and the temperature in Comparative Example 2.
FIG. 30 is a graph showing the relationship between the reflection density and the temperature in Comparative Example 3.
FIG. 31 is a graph showing the relationship between reflection density and temperature in Comparative Example 4.
FIG. 32 is a graph showing the relationship between the reflection density and the temperature in Comparative Example 5.
FIG. 33 is a graph showing a relationship between reflection density and temperature in Comparative Example 6.
[Explanation of symbols]
1 Thermoreversible recording medium
10. Thermo-reversible recording label
11 Support
12 Aluminum reflective layer
13 Reversible thermosensitive layer
14 Protective layer
16 Magnetic thermosensitive layer
22 Rewriting recording section
23 Print display section
24 Magnetic recording unit
25 hollow
26 Rewriting recording section
30 doorway
31 Transport roller
32 Guide roller
33 sensor
34 Magnetic Head
34c control means
35 Platen roller
36 Guide roller
37 Transport roller
38 Ceramic heater
38c Ceramic heater control means
39 Guide roller
40 transport roller
43 sensor
43a sensor
44 Platen roller
45 Transport roller
46 Transport roller
47 Transport roller
48 conveyor belt
49b transport path
50 transport path
51 sensors
52 Platen roller
53 thermal head
53c Thermal head control means
55a transport path switching means
55b conveyance path switching means
56a transport path
56b transport path
57a Limit switch
57b Limit switch
58 Conveyor belt
59 Transport roller
60 Guide roller
Exit 61
70 MD disk cartridge
71 CD-RW
72 video cassettes
101 Protective layer
102 Reversible thermosensitive layer
103 Light reflection layer
104 support
105 adhesive layer or pressure-sensitive adhesive layer
106 middle class
107 Reflection heat dissipation layer
108 second dielectric layer
109 Optical information storage layer
110 first dielectric layer
111 base
112 Hard coat layer
231 wafer
232 wafer substrate
233 Integrated Circuit
234 contact terminal
235 CPU
236 ROM
237 RAM
238 Input / output interface
239a to 239g Storage area

Claims (27)

A heat-sensitive layer containing a resin and an organic low-molecular-weight compound, the transparency of which reversibly changes depending on the temperature; the glass transition temperature change in the heat-sensitive layer is -10 to 5 ° C; A thermoreversible recording medium having a width of 30 ° C. or more. A resin and an organic low-molecular compound, at least a heat-sensitive layer whose transparency reversibly changes depending on temperature, wherein the resin contains an acrylic polyol resin, and a glass transition temperature change in the heat-sensitive layer is −10. A thermoreversible recording medium at a temperature of from 5 to 5 ° C. Including a resin and an organic low-molecular-weight compound, at least having a heat-sensitive layer whose transparency reversibly changes depending on temperature, wherein the resin contains an acrylic resin, and a clearing temperature range in the heat-sensitive layer is 40 ° C. or more. A thermoreversible recording medium characterized by the following. A resin and an organic low-molecular compound, at least a heat-sensitive layer whose transparency reversibly changes depending on temperature, wherein the resin contains an acrylic polyol resin, and a clearing temperature range in the heat-sensitive layer is 30 ° C. A thermoreversible recording medium characterized by the above. The thermoreversible recording medium according to any one of claims 1 to 4, wherein the heat-sensitive layer has a glass transition temperature of 30 to 70C. 6. The thermoreversible recording medium according to claim 1, wherein the resin contains an acrylic resin. The thermoreversible recording medium according to any one of claims 1 to 2, and 4 to 6, wherein the resin contains an acrylic polyol resin. The thermoreversible recording medium according to any one of claims 1 to 7, wherein the resin contains an acrylic polyol resin, and the acrylic polyol resin is crosslinked with an isocyanate compound. The thermoreversible recording medium according to any one of claims 2 and 4 to 8, wherein the acrylic polyol resin has a glass transition temperature (Tg) determined from the following formula of 30 to 60 ° C.
1 / Tg = Σ (Wi / Tgi)
In the above formula, Wi represents the mass fraction of the monomer i, and Tgi represents the glass transition temperature (K) of the homopolymer of the monomer i. The thermoreversible recording medium according to any one of claims 2 and 4 to 9, wherein the acrylic polyol resin has a hydroxyl value of 20 to 130 mgKOH / g. The thermoreversible recording medium according to any one of claims 2 and 4 to 10, wherein the acrylic polyol resin has a refractive index of 1.45 to 1.60. The thermoreversible recording medium according to any one of claims 2 and 4 to 11, wherein the acrylic polyol resin has a weight average molecular weight of 20,000 to 100,000. The thermoreversible recording medium according to any one of claims 1 to 12, wherein the low-molecular organic compound is a compound containing no carboxyl group. The thermoreversible recording medium according to any one of claims 1 to 13, wherein an erasing energy width represented by the following formula when erasing an image immediately after image formation is 20 to 80%.
Erasure energy width (%) = [(E ₂ −E ₁ ) / Ec] × 100
In the above formula, E ₁ represents a lower limit value (mj / dot) of the erase energy, E ₂ represents an upper limit value (mj / dot) of the erase energy, and Ec represents a central value of the erase energy (E ₁ + E _2). ) / 2 (mj / dot). 15. The erasing energy width represented by the following formula when erasing an image after image formation time is 20 to 80%, and a rate of change of the erasing energy width with time is 12% or less. C. The thermoreversible recording medium described in C.
Erasure energy width (%) = [(E ₂ −E ₁ ) / Ec] × 100
In the above formula, E ₁ represents a lower limit value (mj / dot) of the erase energy, E ₂ represents an upper limit value (mj / dot) of the erase energy, and Ec represents a central value of the erase energy (E ₁ + E _2). ) / 2 (mj / dot). The thermoreversible recording medium according to any one of claims 1 to 15, further comprising a support. A thermoreversible recording label, characterized in that the thermoreversible recording label according to any one of claims 1 to 16 has an adhesive layer or a pressure-sensitive adhesive layer on a surface opposite to a surface on which an image is formed. A thermoreversible recording member having an information storage unit and a reversible display unit, wherein the reversible display unit includes the thermoreversible recording medium according to any one of claims 1 to 16. 19. The thermoreversible recording member according to claim 18, wherein the information storage unit and the reversible display unit are integrated. 20. The thermoreversible recording member according to claim 18, wherein the thermoreversible recording member is selected from a card, a disk, a disk cartridge, and a tape cassette. Image forming means for heating the thermoreversible recording medium to form an image on the thermoreversible recording medium; and image erasing means for heating the thermoreversible recording medium to erase the image formed on the thermoreversible recording medium. An image processing apparatus comprising at least one of the above, and the thermoreversible recording medium is the thermoreversible recording medium according to any one of claims 1 to 16. 22. The image processing apparatus according to claim 21, wherein the image forming unit is a thermal head. 23. The image processing apparatus according to claim 21, wherein the image erasing means is one of a thermal head and a ceramic heater. Forming an image on the thermoreversible recording medium by heating the thermoreversible recording medium, and erasing the image formed on the thermoreversible recording medium by heating the thermoreversible recording medium. 17. An image processing method, comprising: the thermoreversible recording medium according to claim 1. The image processing method according to claim 24, wherein the image is formed using a thermal head. 26. The image processing method according to claim 24, wherein the image is erased using one of a thermal head and a ceramic heater. 27. The image processing method according to claim 24, wherein a new image is formed while erasing the image using a thermal head.

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