JP3780198B2 - Color image forming developer kit and image forming method - Google Patents

Description

【００４２】
イエロートナー粒子に上記の如き縮合アゾ系顔料とイエロー染料を特定の比率で含有させることにより、トナー粒子内での着色剤の分散状態が改善され、イエロートナー自身の特性が向上するだけでなく、後述するマゼンタ現像剤やシアン現像剤との組み合わせにより良好なフルカラー画像を得ることが出来る。
【００４３】
特に、用いられる縮合アゾ系顔料が、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ９３、同９４、同９５、同１２８、同１６６の群から選ばれるいずれかであり、且つ、イエロー染料が、Ｃ．Ｉ．Ｓｏｌｖｅｎｔ Ｙｅｌｌｏｗ ９３、同１０５、同１１２、同１６２、同１６３、Ｃ．Ｉ．Ｄｉｓｐｅｒｓ Ｙｅｌｌｏｗ４２、同６４、同１６０、同２０１の群から選ばれるいずれか（それぞれカラーインデックス第４版記載の名称による）である場合、その改善効果は一層良好なものとなる。
【００４４】
マゼンタ現像剤中のマゼンタトナー粒子は、下記構造式（２）で示されるキナクリドン系顔料と下記構造式（３）で示されるモノアゾ系顔料を含有し、その総含有量が１〜２０質量％で、含有量の質量比率が、キナクリドン系顔料：モノアゾ系顔料＝２５：７５〜７５：２５ となるように調製される。
【００４５】
【化８】

〔Ｘ₁とＸ₂は、水素原子、又はアルキル基、アルコキシ基、ハロゲン基から選ばれる置換基を示す。〕
【００４６】
【化９】

【００４７】
マゼンタトナー粒子においても、上記の如きキナクリドン系顔料とモノアゾ系顔料を特定の比率で含有させることにより、トナー粒子内での着色剤の分散状態が改善され、マゼンタトナー自身の特性が向上するだけでなく、前述の如きイエロー現像剤やシアン現像剤との組み合わせにより良好なフルカラー画像を得ることが出来る。
【００４８】
特に、用いられるキナクリドン系顔料が、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２、同２０２、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｖｉｏｌｅｔ １９の群から選ばれるいずれか、及び／又はそれらの固溶体顔料であり、且つ、モノアゾ系顔料が、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ５、同３１、同１４６、同１４７、同１５０、同１７６、同１８４、同１８５、または同２６９の群から選ばれるいずれか（それぞれカラーインデックス第４版記載の名称による）である場合、その改善効果は一層良好なものとなる。
【００４９】
シアン現像剤のシアントナー粒子は、フタロシアニン系顔料を含有し、その含有量が１〜１０質量％となるように調製される。特に、シアン現像剤のトナー粒子に用いられるフタロシアニン系顔料が、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５、同１５：１、同１５：２、同１５：３、同１５：４、同１６、の群から選ばれるいずれか（それぞれカラーインデックス第４版記載の名称による）である場合、前述の如きマゼンタ現像剤やイエロー現像剤との組み合わせにより良好なフルカラー画像を得ることが出来る。
【００５０】
上記の如くトナー粒子中の着色剤の種類と含有量を特定することにより、トナー粒子内の着色剤の含有状態を改善することが可能となり、忠実な色再現を達成した高精細で高解像度のフルカラー画像形成がなされる。また、同時に複数のトナー層を一度に定着しなければならないカラー画像形成時や定着ローラーへのオフセット防止用液体の塗布量が少ない定着装置を用いた場合であっても、加熱定着に対するトナー粒子内の着色剤の影響を最小限に抑制することで、定着装置の定着ローラー等の定着部材表面にトナーが付着残余することを未然に防止することが出来るので、多数枚プリントアウト時においても良好な色再現を安定して得ることを知見し、本発明を完成するに至った。
【００５１】
本発明のカラー画像形成用現像剤キットは、イエロー現像剤、マゼンタ現像剤、及びシアン現像剤の３色の有彩色現像剤以外に、色調調整等の目的で他の有彩色現像剤や黒色現像剤を構成に加えることが可能である。また、本発明に係るトナー粒子は、トナー特性に悪影響を及ぼさない範囲内で上記の如き着色剤以外のものを単独又は混合、或いは固溶体の状態で併用することが出来る。
【００５２】
黒色現像剤用の黒色着色剤には、カーボンブラック、磁性体、又は上述の如きイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用出来る。
【００５３】
本発明に好ましく用いられるカーボンブラックは、窒素吸着比表面積が１００ｍ²／ｇ以下であることが好ましく、窒素吸着比表面積が１００ｍ²／ｇよりも大きくなるとトナー中への分散が困難となり、トナーの帯電性や着色力に問題を生じる。また、重合法によりトナーを製造する際にはモノマーの重合性にも影響を及ぼすため使用に適さない。
【００５４】
尚、カーボンブラックの窒素吸着比表面積の測定は、「ＡＳＴＭ Ｄ３０３７−７９」に準拠して行う。
【００５５】
本発明に係る現像剤中のトナー粒子は、フロー式粒子像測定装置で計測される個数基準の円相当径−円形度スキャッタグラムにおいて、円相当個数平均径Ｄ１（μｍ）が２〜１０μｍ、平均円形度が０．９５０〜０．９９５で、円形度標準偏差が０．０４０未満であり、且つ、結着樹脂の主成分がスチレン−（メタ）アクリル系樹脂であり、該結着樹脂のテトラヒドロフラン（ＴＨＦ）の可溶分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）におけるピーク分子量が５０００〜３万で、ＴＨＦ不溶分が５〜３５質量％となるようにトナー粒子の粒子形状と結着樹脂成分を精密に制御することにより、トナー特性をバランス良く改善することが出来る。
【００５６】
即ち、トナー粒子の円相当個数平均径Ｄ１（μｍ）を２〜１０μｍ、より好ましくは３〜６μｍと小粒径化することにより、画像の輪郭部分、特に文字画像やラインパターンの現像での再現性が良好なものとなる。
【００５７】
一般にトナー粒子を小粒径化すると必然的に微小粒子のトナーの存在率が高くなる為、トナーを均一に帯電させることが困難となり画像カブリを生じるばかりか、画像形成装置とのマッチングにも支障を招いていた。
【００５８】
しかしながら、本発明に係る現像剤は、トナー粒子の円形度頻度分布の平均円形度を０．９５０〜０．９９５、好ましくは０．９６５〜０．９９５、より好ましくは０．９７５〜０．９９０とすることにより、従来では困難であった小粒径を呈するトナーの転写性が大幅に改善されると共に低電位潜像に対する現像能力が格段に向上する。特に上記の如き傾向は、デジタル方式の微小スポット潜像を現像する場合や中間転写体を用い多数回の転写を行うフルカラーの画像形成の際に非常に有効で、画像形成装置とのマッチングも良好なものとなる。
【００５９】
更に、本発明に係る現像剤は、トナー粒子の円形度頻度分布の円形度標準偏差を０．０４０未満、好ましくは０．０３５未満、より好ましくは０．０１５以上０．０３０未満とすることにより、トナー担持体上にトナーの薄層を形成する際に、トナー帯電量を適切なものとすることが可能となり、前述の如き問題を大幅に改善することが出来る。
【００６０】
ところで、一般に上記のような特定の粒度分布や形状分布を呈するトナーを用いた場合、トナー担持体の表面にトナーの薄層を形成する際にトナー粒子のすり抜け現象を生じ、度々著しい画像劣化を引き起こすことがある。しかしながら本発明のトナーにおいては、トナー粒子に含有される着色剤の種類と含有量を特定することによってトナー粒子内での着色剤の分散状態が改善され、トナーへの電荷付与を迅速に、しかも均一に行うことが出来るので上記の如き画像劣化を未然に防止することが出来る。
【００６１】
本発明におけるトナーの円相当径、円形度、及びそれらの頻度分布とは、トナー粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明ではフロー式粒子像測定装置「ＦＰＩＡ−１０００型」（東亜医用電子社製）を用いて測定を行い、下式を用いて算出した。
【００６２】
【数１】

【００６３】
ここで、「粒子投影面積」とは二値化されたトナー粒子像の面積であり、「粒子投影像の周囲長」とは該トナー粒子像のエッジ点を結んで得られる輪郭線の長さと定義する。
【００６４】
本発明における円形度はトナー粒子の凹凸の度合いを示す指標であり、トナー粒子が完全な球形の場合には１．０００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【００６５】
本発明において、トナーの個数基準の粒径頻度分布の平均値を意味する円相当個数平均径Ｄ１（μｍ）と粒径標準偏差ＳＤｄは、粒度分布の分割点ｉでの粒径（中心値）をｄｉ、頻度をｆｉとすると次式から算出される。
【００６６】
【数２】

【００６７】

【００６８】
【数３】

【００６９】
具体的な測定方法としては、容器中に予め不純固形物などを除去したイオン交換水１０ｍｌを用意し、その中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルホン酸塩を加えた後、更に測定試料を０．０２ｇを加え、均一に分散させる。分散手段としては、超音波分散機「ＵＨ−５０型」（エスエムテー社製）に振動子として５φのチタン合金チップを装着したものを用い、５分間分散処理を行い、測定用の分散液とする。その際、該分散液の温度が４０℃以上にならないように適宜冷却する。
【００７０】
トナー粒子の形状測定には、前記フロー式粒子像測定装置を用い、測定時のトナー粒子濃度が３０００〜１万個／μＬとなるように該分散液濃度を再調整し、トナー粒子を１０００個以上計測する。計測後、このデータを用いてトナー粒子の円相当径や円形度頻度分布等を求める。
【００７１】
尚、本発明に係るトナー粒子は、上記の如く粒子形状を制御することにより比表面積は減少していくので、トナー粒子に含有される着色剤の種類と含有量を特定する効果が著しいものとなる。
【００７２】
本発明に係る現像剤のトナー粒子に用いられる結着樹脂としては、一般的に用いられているスチレン−（メタ）アクリル共重合体、ポリエステル樹脂、エポキシ樹脂、スチレン−ブタジエン共重合体が挙げられ、特にスチレン−（メタ）アクリル系樹脂を主成分とすることが上記の如き着色剤との親和性の観点から好ましい。また、該結着樹脂のテトラヒドロフラン（ＴＨＦ）の可溶分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）におけるピーク分子量が５０００〜３万で、ＴＨＦ不溶分が５〜３５質量％となるようにトナー粒子の粒子形状と結着樹脂成分を精密に制御することにより、トナー特性をバランス良く改善することが出来る。
【００７３】
本発明において、結着樹脂成分のＴＨＦ可溶分のＧＰＣは以下の条件で測定される。尚、試料は予め溶媒に１２時間以上分散／溶解させた後、耐溶剤性メンブランフィルター（ポア径：０．４５μｍ）で濾過したものを用いる。
【００７４】

【００７５】
本発明において結着樹脂のＴＨＦ不溶分とは、トナー粒子中の樹脂組成物のＴＨＦに対して不溶性となった樹脂成分の質量割合を示し、架橋成分を含む樹脂組成物の架橋の程度を示す目安となるが、ＴＨＦ不溶分が０質量％であっても必ずしも架橋していないという訳ではない。ＴＨＦ不溶分とは、以下のように測定された値をもって定義する。
【００７６】
即ち、トナー粒子を０．５〜１．０ｇ範囲で秤量し（Ｗ₁ｇ）、「円筒濾紙Ｎｏ．８６Ｒ」（東洋濾紙製）に入れ、そのままソックスレー抽出器にセットし、ＴＨＦ１００〜２００ｍｌを用いて２０時間抽出する。次いで、ＴＨＦによって抽出された可溶成分を回収し、その質量（Ｗ₂ｇ）を求める。一方、該トナー粒子中に含まれている顔料等の他の構成成分のうち、ＴＨＦに可溶な成分の質量（Ｗ₃ｇ）と不溶な成分の質量（Ｗ₄ｇ）を別途、公知の方法で測定しておき、下記の式に従ってトナー粒子中の結着樹脂のＴＨＦ不溶分を算出する。
【００７７】
【数４】

【００７８】
重合法により直接トナー粒子を得る方法においては、それらを形成するための単量体が用いられる。具体的にはスチレン；ｏ−（ｍ−，ｐ−）メチルスチレン、ｍ−（ｐ−）エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体；ブタジエン、イソプレン、シクロヘキセン、（メタ）アクリロニトリル、アクリル酸アミドの如きエン系単量体が好ましく用いられる。これらは、単独、または、一般的には出版物ポリマーハンドブック第２版ＩＩＩ−Ｐ１３９〜１９２（Ｊｏｈｎ Ｗｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を適宜混合して用いられる。理論ガラス転移温度が４０℃未満の場合にはトナーの保存安定性や耐久安定性の面から問題が生じやすく、一方７５℃を超える場合はトナーの定着点の上昇をもたらし、定着性や色再現性の悪化を招く。
【００７９】
さらに、本発明においては、トナー粒子の機械的強度と色再現性を高めるために結着樹脂の合成時に架橋剤を用いることが好ましい。
【００８０】
本発明に係るトナーに用いられる架橋剤としては、２官能の架橋剤として、ジビニルベンゼン、ビス（４−アクリロキシポリエトキシフェニル）プロパン、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコール＃２００、＃４００、＃６００の各ジアクリレート、ジプロピレングリコールジアクリレート、ポリプロピレングリコールジアクリレート、ポリエステル型ジアクリレート（ＭＡＮＤＡ日本化薬）、及び上記のジアクリレートをメタクリレートに代えたものが挙げられる。
【００８１】
多官能の架橋剤としては、ペンタエリスリトールトリアクリレート、トリメチロールエタントリアクリレート、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート及びそのメタクリレート、２，２−ビス（４−メタクリロキシ、ポリエトキシフェニル）プロパン、ジアリルフタレート、トリアリルシアヌレート、トリアリルイソシアヌレート及びトリアリルトリメリテートが挙げられる。
【００８２】
これらの架橋剤は、他のビニル系単量体１００質量部に対して、好ましくは０．０５〜１０質量部、より好ましくは０．１〜５質量部であることが良い。
【００８３】
本発明において、上述の結着樹脂と共にポリエステル樹脂やポリカーボネート樹脂等の極性を有する樹脂（以下、「極性樹脂」と称す）を併用することが出来る。トナー中に極性樹脂を添加することによって、トナー粒子中の着色剤の含有状態を好ましい状態にすることが容易となる。
【００８４】
例えば、後述する懸濁重合法等により直接トナーを製造する場合には、分散工程から重合工程に至る重合反応時に上記の如き極性樹脂を添加すると、トナー粒子となる重合性単量体組成物と水系分散媒体の呈する極性のバランスに応じて、添加した極性樹脂がトナー粒子の表面に薄層を形成したり、トナー粒子表面から中心に向け傾斜性をもって存在するように制御することが出来る。この時、本発明に係る着色剤と相互作用を有するような極性樹脂を用いることによって、トナー粒子中への着色剤の存在状態を望ましい形態にすることが可能で、特に酸価が１〜４０ｍｇＫＯＨ／ｇを呈する極性樹脂を用いることが好ましい。
【００８５】
上記極性樹脂の添加量は、結着樹脂１００質量部に対して１〜２５質量部使用するのが好ましく、より好ましくは２〜１５質量部である。１質量部未満ではトナー粒子中での極性樹脂の存在状態が不均一となり、逆に２５質量部を超えるとトナー粒子表面に形成される極性樹脂の薄層が厚くなるため、何れの場合も系着色剤の含有状態を制御するのが困難になり、その機能を十分に発現することが出来ない。
【００８６】
また、上記の如き極性樹脂はそれぞれ一種類の重合体に限定されるわけではなく、例えば反応性ポリエステル樹脂を同時に二種類以上用いることや、ビニル系重合体を二種類以上用いることが可能であり、さらに全く種類の異なる重合体、例えば反応性の無いポリエステル樹脂、エポキシ樹脂、ポリカーボネート樹脂、ポリオレフィン、ポリ酢酸ビニル、ポリ塩化ビニル、ポリアルキルビニルエーテル、ポリアルキルビニルケトン、ポリスチレン、ポリ（メタ）アクリルエステル、メラミンホルムアルデヒド樹脂、ポリエチレンテレフタレート、ナイロン、ポリウレタン等様々な重合体を必要に応じてバインダー樹脂に添加することが出来る。
【００８７】
本発明において使用し得るワックス成分としては、具体的には、パラフィンワックス、マイクロクリスタリンワックス、ペトロラクタム等の石油系ワックス及びその誘導体、モンタンワックス及びその誘導体、フィッシャートロプシュ法による炭化水素ワックス及びその誘導体、ポリエチレンに代表されるポリオレフィンワックス及びその誘導体、カルナバワックス、キャンデリラワックス等の天然ワックス及びそれらの誘導体等が挙げられ、誘導体には酸化物や、ビニルモノマーとのブロック共重合物、グラフト変性物も含まれる。また、高級脂肪族アルコール等のアルコール；ステアリン酸、パルミチン酸等の脂肪酸或いはその化合物；酸アミド、エステル、ケトン、硬化ヒマシ油及びその誘導体、植物ワックス、動物ワックスが挙げられる。これらは単独、もしくは併用して用いることができる。
【００８８】
これらの中でも、ポリオレフィン、フィッシャートロプシュ法による炭化水素ワックス、石油系ワックス、高級アルコール、若しくは、高級エステルを使用した場合に、現像性や転写性の改善効果が更に高くなる。なお、これらのワックス成分には、トナーの帯電性に影響を与えない範囲で酸化防止剤が添加されていてもよい。また、これらのワックス成分は、結着樹脂１００質量部に対して１〜３０質量部使用するのが好ましい。
【００８９】
本発明に用いられるワックス成分としては、「ＡＳＴＭ Ｄ３４１８−８２」に準じて測定されたＤＳＣ曲線における主体吸熱ピーク温度（融点）が３０〜１５０℃、より好ましくは４０〜１２０℃、特に好ましくは５０〜９０℃の範囲にある化合物が好ましい。
【００９０】
上記の如き熱特性を呈するワックス成分を用いることにより、得られるトナーの良好な定着性はもとより、該ワックス成分による離型効果が効率良く発現され、十分な定着領域が確保されることにより、良好な色再現性を呈するカラー画像が得られると共に、従来から知られるワックス成分による現像性、耐ブロッキング性や画像形成装置への悪影響を排除することが出来る。特に、トナーの粒子形状が球形化するに従い、トナーの比表面積は減少していくので、ワックス成分の熱特性と分散状態を制御することは非常に効果的なものとなる。
【００９１】
ワックス成分の主体吸熱ピーク温度（融点）の測定には、例えば「ＤＳＣ−７」（パーキンエルマー社製）を用いる。装置検出部の温度補正にはイリジウムと亜鉛の融点を用い、熱量の補正についてはイリジウムの融解熱を用いる。測定に際しては、測定サンプルをアルミニウム製パンに入れたものと、対照用にアルミニウム製パンのみのもの（空パン）をセットし、２０〜１８０℃の測定領域を昇温速度１０℃／ｍｉｎで昇温した時に得られるＤＳＣ曲線から主体吸熱ピーク温度（融点）が求められる。尚、ワックス成分のみを測定する場合には、測定時と同一条件で昇温−降温を行って前履歴を取り除いた後に測定を開始する。また、トナー中に含まれた状態のワックス成分を測定する場合には、前履歴を取り除く操作を行わず、そのままの状態で測定を行なう。
【００９２】
本発明に係るトナー粒子には、摩擦帯電量や帯電速度を微調整することを目的として、公知の荷電制御剤を併用することができ、特に帯電速度が速く、且つ、一定の帯電量を安定して維持できる荷電制御剤が好ましい。更に、トナー粒子を直接重合法により製造する場合には、重合阻害性が無く水系分散媒体への可溶化物の無い荷電制御剤が好ましい。具体的化合物としては、ネガ系荷電制御剤としてサリチル酸、ナフトエ酸、ダイカルボン酸の如きカルボン酸の金属化合物；スルホン酸又はカルボン酸基を側鎖に持つ高分子型化合物；ホウ素化合物；尿素化合物；ケイ素化合物；カリークスアレーン等が挙げられる。ポジ系荷電制御剤として、四級アンモニウム塩；該四級アンモニウム塩を側鎖に有する高分子型化合物；グアニジン化合物；イミダゾール化合物等が挙げられる。
【００９３】
本発明に係る現像剤はトナー粒子と共に無機微粉体を添加する。これにより、現像性、転写性、帯電安定性、流動性及び耐久性が向上する。
【００９４】
本発明に好ましく用いられる無機微粉体としては、公知のものが使用可能であるが、特にシリカ，アルミナ，チタニアあるいはその複酸化物の中から選ばれることが好ましい。更には、シリカであることがより好ましい。例えば、かかるシリカは硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及びアルコキシド，水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、また、Ｎａ₂ＯやＳＯ₃ ^2-等の製造残渣の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム，塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能でありそれらも包含する。
【００９５】
本発明に用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与え、トナー１００質量部に対して０．３〜８質量部使用され、好ましくは０．５〜５質量部である。
【００９６】
上記の如き比表面積が制御された無機微粉末を用いることによって、トナー表面近傍に着色剤が存在するような場合においてもトナー粒子への水分吸着量の抑制がなされ、帯電量や帯電速度の制御効果が増大する。また、着色剤による静電潜像担持体や中間転写体等への汚染や削れに起因する画像不良を未然に防止する。更に、トナーに適度な流動性が付与されるので、トナーの均一帯電性が相乗的に良化し、連続で多数枚プリントアウトを繰り返しても、上記の如き優れた効果が維持される。
【００９７】
比表面積が３０ｍ²／ｇ未満の場合には、トナーに適度な流動性を付与することが困難であり、また、着色剤に起因するトナー担時体の汚染への防止効果が小さくなってしまう。比表面積が４００ｍ²／ｇを超える場合には、連続して多数枚プリントアウト時に該無機微粉末がトナー粒子表面に埋め込まれるために、トナーの流動性が低下する場合がある。
【００９８】
また、無機微粉末の添加量が０．３質量部未満の場合には、添加効果が発現されず、８質量部を超えると、トナーの帯電性や定着性に問題を生じるだけでなく、遊離した無機微粉体により画像形成装置とのマッチングが著しく悪化する。
【００９９】
また、本発明に用いられる無機微粉体は、必要に応じ、疎水化、帯電性制御等の目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機硅素化合物、有機チタン化合物等の処理剤、或いは種々の処理剤を併用して処理されていることも可能であり好ましい。
【０１００】
比表面積の測定には、比表面積測定装置「オートソーブ１」（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法により比表面積を算出した。
【０１０１】
更に、無機微粉体は、高い帯電量を維持し、高転写率と画像形成装置への良好なマッチングを達成する為に、少なくともシリコーンオイルで処理されることが好ましい。
【０１０２】
本発明に係るトナーにおいては、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばポリ弗化エチレン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末などの研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末などの流動性付与剤；ケーキング防止剤、或いは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることも出来る。
【０１０３】
本発明の乾式トナーは、そのまま一成分系現像剤として或いは、キャリアと混合して二成分系現像剤として使用することができる。
【０１０４】
二成分系現像剤として用いる場合、例えば、トナーと混合させる磁性キャリアとしては、鉄、銅、亜鉛、ニッケル、コバルト、マンガン、クロム等より選ばれる元素から、単独又は複合フェライト状態で構成される。この際に使用する磁性キャリアの形状は、球状、扁平、不定形等のものがあり、更に、磁性キャリアの表面状態の微細構造（例えば、表面凹凸性）を適宜に制御したものを用いることも出来る。また、表面を樹脂で被覆した樹脂被覆キャリアも好適に用いることが出来る。使用するキャリアの平均粒径は、好ましくは１０〜１００μｍ、より好ましくは２０〜５０μｍである。また、これらのキャリアとトナーを混合して二成分系現像剤を調製する場合の現像剤中のトナー濃度は、好ましくは２〜１５質量％程度である。
【０１０５】
本発明の乾式トナーを製造する方法としては、結着樹脂、着色剤、ワックス成分等を加圧ニーダー等により溶融混練した後、冷却した混練物を所望のトナー粒径に微粉砕し、更に微粉砕物を分級して粒度分布を調整してトナーにする粉砕法；特公昭３６−１０２３１号公報、特開昭５９−５３８５６号公報及び特開昭５９−６１８４２号公報に記載されている懸濁重合法を用いて直接トナーを製造する方法；特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用いて溶融混練物を空気中に霧化して球状トナーを製造する方法；及びソープフリー重合法に代表される乳化重合法等、公知の方法を用いることが可能である。
【０１０６】
ところで、トナー粒子中に添加される着色剤は、一般に親水性の官能基を多く有しているため、水系分散媒体中で重合性単量体組成物の造粒粒子を重合してトナー粒子を形成する際、分散質である重合性単量体組成物と水系媒体の界面に向け移行し、結果としてトナー粒子表面近傍で再凝集を生じる場合がある。このような場合、得られたトナー粒子の帯電量や帯電速度のみならず、加熱定着等に対して悪影響を及ぼし、画像形成装置とのマッチングに支障をきたすようになる。
【０１０７】
これに対して、本発明者等は、上記の如き着色剤を所望の配合量の範囲内に適宜調整しながら、重合性単量体組成物の一部分と共に予め分散／混合した後に懸濁重合法によりトナーを製造することによって、それら着色剤をトナー粒子の内部に良好な状態で固定化することが出来ることを見出した。例えば、マゼンタ現像剤のトナー粒子の場合、キナクリドン系着色剤とモノアゾ系着色剤を重合性単量体組成物の一部分と共に予め分散／混合した顔料分散組成物を製造し、これを残りの重合性単量体組成物と共に懸濁重合法によるトナーの製造に供することにより、キナクリドン系着色剤やモノアゾ系着色剤の単独での再凝集が防止しされると共に、トナー粒子中にキナクリドン系着色剤とモノアゾ系着色剤の相互作用を保ったまま内包化することが可能となり、得られるトナー粒子に望ましい帯電特性や発色性、更には定着性を付与することが出来る。また、画像形成装置とのマッチングも著しく向上する。上記の如き効果は、顔料分散組成物を製造する際に、荷電制御剤や上述の如き極性樹脂を共存させることによって一層良好なものとなる。
【０１０８】
本発明に係るトナーの製造方法において、水系分散媒体を調製する場合に使用する分散剤としては、公知の無機系及び有機系の分散剤を用いることができる。具体的には、無機系の分散剤としては、例えば、リン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸マグネシウム、炭酸カルシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナ等が挙げられる。また、有機系の分散剤としては、例えば、ポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、デンプン等を用いることができる。
【０１０９】
また、市販のノニオン、アニオン、カチオン型の界面活性剤の利用も可能である。例えば、ドデシル硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等を用いることが出来る。
【０１１０】
本発明に係るトナーの製造方法においては、無機系の難水溶性の分散剤が好ましく、しかも酸に可溶性である難水溶性無機分散剤を用いるとよい。また、本発明においては、難水溶性無機分散剤を用い、水系分散媒体を調製する場合に、これらの分散剤が重合性ビニル系単量体１００質量部に対して、０．２〜２．０質量部となるような割合で使用することが好ましい。また、本発明においては、重合性単量体組成物１００質量部に対して３００〜３，０００質量部の水を用いて水系分散媒体を調製することが好ましい。
【０１１１】
本発明において、上記したような難水溶性無機分散剤が分散された水系分散媒体を調製する場合には、市販の分散剤をそのまま用いて分散させてもよいが、細かい均一な粒度を有する分散剤粒子を得るために、水等の液媒体中で、高速撹拌下、上記したような難水溶性無機分散剤を生成させて調製してもよい。例えば、リン酸三カルシウムを分散剤として使用する場合、高速撹拌下でリン酸ナトリウム水溶液と塩化カルシウム水溶液を混合してリン酸三カルシウムの微粒子を形成することで、好ましい分散剤を得ることが出来る。
【０１１２】
次に、本発明のトナーの製造方法に使用する重合性単量体組成物について説明する。該重合性単量体組成物は、少なくとも、重合性ビニル系単量体、キナクリドン系着色剤、及びモノアゾ系着色剤、好ましくは、これに加えて荷電制御剤、ワックス成分、更に必要に応じて各種の添加物を溶解、混合して調製される。
【０１１３】
この際に用いる重合性ビニル系単量体としては、前記に挙げたような重合性単量体を理論ガラス転移温度（Ｔｇ）が４０〜７５℃を示すように適宜混合して用いられる。特に、Ｔｇが高い場合には、フルカラー画像を形成するためのカラートナーを製造した場合において、各色トナーの定着時の混色性が低下し、色再現性に乏しく、更にＯＨＰ画像の透明性が低下するため好ましくない。
【０１１４】
また、本発明に係るトナーの製造方法に用いる重合開始剤としては、具体的には、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系又はジアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシドの如き過酸化物系重合開始剤が用いられる。これらの重合開始剤の使用量は、目的とする重合度により変化するが、一般的には、重合性ビニル系単量体１００質量部に対して５〜２０質量部用いられる。重合開始剤の種類は、重合法により若干異なるが、１０時間半減期温度を参考に、単独又は混合して使用される。
【０１１５】
重合性単量体組成物中には、重合度を制御するため、公知の架橋剤、連鎖移動剤及び重合禁止剤等を更に添加し用いてもよい。これらの添加剤は、前記重合性単量体組成物中に予め添加しておくこともできるし、また、必要に応じて、重合反応の途中で適宜に添加することもできる。
【０１１６】
本発明の画像形成方法は、複数の画像形成ステップを順次繰り返すことによって、フルカラー画像を形成する画像形成方法において、
第１の画像形成ステップ以降によって既に上述した有彩色現像剤による画像形成が開始された後に、最終画像形成ステップによって黒色現像剤による画像が形成されることによってフルカラー画像形成が成し遂げられ、
各画像形成ステップが、少なくとも（ａ）静電潜像を担持するための像担持体を帯電する帯電工程；（ｂ）帯電された像担持体に像露光によって静電潜像を形成する露光工程；（ｃ）該静電潜像をトナー担持体の表面に担持されているトナーによって現像し、トナー像を形成する現像工程；（ｄ）該像担持体の表面に形成されたトナー像を中間転写体を介して、又は介さずに転写材に転写する転写工程； 及び（ｅ）転写工程後に該像担持体表面に残存しているトナーをクリーニング除去するクリーニング工程；を有し、クリーニングされた像担持体を用いて上記（ａ）乃至（ｅ）の工程を繰り返し、
且つ、転写材上に転写されたトナー像を加熱定着して定着画像を形成する定着工程を有している。
【０１１７】
次に、添付図面を参照しながら、本発明の画像形成方法について説明する。
【０１１８】
図１は本発明の画像形成方法をフルカラー画像形成装置に適応した一例であり、複数の画像形成部にて各々異なった色のトナー像を形成し、これらを同一転写材上に順次重ね合わせて転写することで多色画像を形成する画像形成方法を用いたフルカラー画像形成装置を示す概略的説明図である。
【０１１９】
フルカラー画像形成装置本体には、第１の画像形成ユニットＰａ、第２の画像形成ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄが併設されており、各々の画像形成装置ユニットで異なった色のトナー像が現像された後、転写材搬送ベルトによって搬送される転写材上に転写され、更に加熱加圧定着されることによってフルカラー画像が得られる。
【０１２０】
上記画像形成装置に併設される各画像形成ユニットの構成について、第１の画像形成ユニットＰａを例に挙げて説明する。
【０１２１】
第１の画像形成ユニットＰａには、静電潜像担持体として直径２４ｍｍφの感光体ドラム１９ａを具備し、感光体ドラム１９ａは矢印ａの方向に回転移動する。
【０１２２】
帯電手段として、直径１２ｍｍφの一次帯電ローラー１６ａが感光体ドラム１９ａの表面に接するように配設されている。一次帯電ローラー１６ａにより均一に一次帯電された感光体ドラム１９ａには、露光装置１３ａより画像信号に応じて照射されるレーザー光１４ａによって静電潜像が形成される。
【０１２３】
現像装置１７ａは、感光体ドラム１９ａの表面上に形成された静電潜像を現像してトナー像を形成する為の現像手段を有しており、第１色目のトナーと該トナーの薄層を表面に担持した直径１８ｍｍφの現像ローラー１５ａがトナーの薄層を介して感光体ドラム１９ａに接するように配設されており、第１色目のトナー像が現像される。
【０１２４】
感光体ドラム１９ａ上に現像された第１色目のトナー像は、ベルト状の転写材担持体２０によって搬送されてくる転写材（記録材）Ｓの表面に転写手段としての転写ブレード１１ａによって転写される。この転写ブレード１１ａは、転写材担持体２０の裏面に当接して、バイアス印加手段１２ａによって転写バイアスを印加し得るものである。
【０１２５】
転写が終了した感光体ドラム１９ａの表面は、クリーニング装置１８ａにより転写残余のトナーが除去され、引き続き行われる次の静電潜像形成の為に供せられる。
【０１２６】
本発明に係る画像形成装置は、第１の画像形成ユニットＰａと同様の構成で、現像装置に保有されるトナーの色が異なる第２の画像形成装置ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄの４つの画像形成装置ユニットを併設するものである。例えば、第１の画像形成装置ユニットＰａにはイエロートナー、第２の画像形成装置ユニットＰｂにはマゼンタトナー、第３の画像形成装置ユニットＰｃにはシアントナー、更に第４の画像形成装置ユニットＰｄにはブラックトナーを各々用い、各画像形成装置ユニットの転写部で各色トナー像が転写材上に順次転写される。この際、この工程中にレジストレーションを合わせつつ転写材を移動させ、同一転写材上に各色トナーは重ね合わされ、終了すると分離帯電器２１によって転写材担持体２０上から転写材Ｓが分離され、搬送ベルトの如き搬送手段によって定着器２３に送られ、ただ一回の定着によって所望のフルカラー画像が得られる。
【０１２７】
図１において、転写材担持体２０は無端のベルト状部材であり、このベルト部材は画像形成の進行に伴い、駆動ローラー８０によって矢印ｅの方向に移動する。転写材担持体２０の周囲には、ベルト従動ローラー８１、ベルト除電装置８２、及びベルトクリーニング装置８３が配設され、また、一対のレジストローラー２４が転写材ホルダー内の転写材Ｓを転写材担持体に搬送する為に設けられている。
【０１２８】
上記の如き画像形成装置において、転写手段としては、転写材担持体の裏面側に当接する転写ブレードに代えて、ローラー状の転写ローラーを用いたり、コロナ帯電器の如き非接触の帯電手段を用いることも可能である。
【０１２９】
また、転写材を搬送する為の搬送手段としては、加工の容易性や耐久性の観点からテトロン繊維のメッシュを用いた搬送ベルトやポリエチレンテレフタレート系樹脂、ポリイミド系樹脂、及びウレタン系樹脂の如き薄い誘電体シートを用いた搬送ベルトが用いられるが、ドラム式の搬送手段を有する構成としても良い。
【０１３０】
上記の如き画像形成装置では、各画像形成装置ユニットの転写部において、同一転写材上に各色トナー像を順次転写する為、先に転写されたトナー像が後から転写されてくるトナー像を担持する感光体ドラムと接する。この際、先に転写が完了している転写材上のトナー像を形成するトナー粒子中に不安定な帯電状態にあるものが存在する場合、続いて転写が行われる感光体ドラムに引き戻される所謂「再転写現象」を生じ、画質低下を招く発端となる。しかしながら、本発明においては、有彩色現像剤の各々のトナー粒子中の着色剤の種類と含有量を特定することで、上記の如き画像不良を未然に防止することが出来る。
【０１３１】
尚、本発明のカラー画像形成用現像剤キットは、静電潜像担持体に形成された静電潜像を現像することによって形成したトナー像を中間転写体に転写する一次転写工程、及び中間転写体に転写されたトナー像を転写材に転写する二次転写工程を有する画像形成装置にも良好に適応することが可能である。
【０１３２】
本発明の画像形成方法に用いられる加熱加圧手段とは、転写材上のトナー画像を加熱加圧定着して定着画像を形成するものであり、前記加熱加圧手段は、（ｉ）少なくとも加熱体を有する回転加熱部材と該回転加熱部材と相互圧接してニップ部を形成する回転加圧部材を有し、（ｉｉ）転写材上のトナー画像との接触面に塗布されるオフセット防止用液体の消費量が０〜０．０２５ｍｇ／ｃｍ²（転写材の単位面積基準）に設定されており、（ｉｉｉ）前記ニップ部で転写材を挟持搬送しながら、前記回転加熱部材と回転加圧部材によって転写材上のトナー画像を加熱加圧するものである。
【０１３３】
加熱定着手段の一部を構成する回転加熱部材とは、転写材上のトナー画像を定着するための熱を付与するためのものであって、（ｉ）熱ローラー方式の加熱加圧手段に用いられ、内部にトナー画像に熱を付与する為の加熱体を有する円筒状部材、（ｉｉ）フィルム方式の加熱加圧手段に用いられ、内部にトナー画像に熱を付与する為の支持体に固定支持させた加熱体を有し、該加熱体に圧接されながら移動駆動する円筒状の耐熱性エンドレスフィルム状部材、（ｉｉｉ）電磁誘導方式の加熱加圧手段に用いられ、内部に磁界発生手段を有し、該磁界発生手段の作用で電磁誘導発熱することによってトナー画像に熱を付与する為の発熱層を有する円筒状の耐熱性エンドレスフィルム状部材、等である。
【０１３４】
また、回転加圧部材とは、前記回転加熱部材と相互圧接してニップ部を形成し、該ニップ部で転写材を挟持搬送しながら転写材上のトナー画像を加熱加圧するものである。
【０１３５】
本発明の画像形成方法において、転写材上のトナー画像との接触面に塗布されるオフセット防止用液体の消費量は０〜０．０２５ｍｇ／ｃｍ²（転写材の単位面積基準）で、より好ましくは、オフセット防止用液体が全く塗布されない状態に設定される。これによって上記の如きオフセット防止用液体に起因する問題点を未然に解決することが出来ると共に、上記の如き現像剤を用いることで加熱加圧手段の性能を長期にわたって維持し、優れた定着画像を得ることが可能となる。
【０１３６】
オフセット防止用液体の消費量の測定には、対象となる加熱加圧手段の最大通紙域に対応した一般事務用再生紙（再生パルプの配合率≧７０％）を用い、該再生紙を１００枚分通紙した際に消費されるオフセット防止用液体の重量（ｍｇ）を用いた再生紙の総面積（ｃｍ²）で除した値（ｍｇ／ｃｍ²）をもって定義される。
【０１３７】
上記の如き形状分布を呈するトナー粒子は、一般に比表面積や体積が小さくなる傾向があり、例えば、キナクリドン系着色剤のように針状結晶を呈する顔料組成物を添加した場合、針状結晶の先端部等がトナー粒子の表面近傍に偏在したり、また、甚だしい場合には、再凝集体が粒子表面に沿って配列したような状態となり、トナー粒子の表面抵抗や帯電特性に悪影響を及ぼし、現像特性や転写特性、画像形成装置とのマッチングを低下させるばかりか、加熱加圧定着手段に対しては、特に、転写材上のトナー画像との接触面にオフセット防止用液体の塗布量が少ない加熱加圧定着手段を用いる場合に影響が見られ、連続で多数枚プリントアウトを繰り返したり、転写材上に複数のトナー層が形成されるカラー画像を定着する際に定着装置が急激に温度低下を引き起こすような際に、定着画像表面に「画像剥がれ」と称される直径２ｍｍ程度の定着不良を数ヶ所にわたって生じる。この際、加熱加圧定着手段にも、剥がれ落ちた定着画像の微小な破片がオフセットする為、加熱加圧定着手段に重大な問題を生じる。特に上記の如き加熱加圧手段を用いる場合に顕在化する。
【０１３８】
しかしながら、本発明に係るトナー粒子は、着色剤の種類と含有量を特定することでトナー粒子内の分散状態を改善し、着色剤の再凝集等を抑制することが出来るので、上記の如き問題を事前に予防することが出来る。
【０１３９】
【実施例】
以下、具体的実施例によって本発明を説明するが、本発明はなんらこれらに限定されるものではない。
【０１４０】
（トナーの製造例１）
高速撹拌装置クレアミックス（エムテクニック社製）を具備した２リットル用４つ口フラスコ中に、イオン交換水７００ｇと０．１ｍｏｌ／Ｌ−Ｎａ₃ＰＯ₄水溶液８００ｇを投入し、高速撹拌装置の回転数を１５０００ｒｐｍに設定し、６０℃に加温せしめた。ここに１．０ｍｏｌ／Ｌ−ＣａＣｌ₂水溶液７０重量部を添加し、微小な難水溶性分散剤Ｃａ₃（ＰＯ₄）₂を含む水系分散媒体を調製した。更に希塩酸により水系分散媒体のｐＨが５．５となるように再調製した。
【０１４１】
一方、分散質として、
・スチレン単量体 ７７質量部
・２−エチルヘキシルアクリレート単量体 ２３質量部
・ジビニルベンゼン単量体 ０．２質量部
・縮合アゾ系顔料 ３質量部
（Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ ９３）
・イエロー染料 ３質量部
（Ｃ．Ｉ．Ｓｏｌｖｅｎｔ Ｙｅｌｌｏｗ １６２）
・ポリエステル樹脂 ５質量部
（ピーク分子量＝４５００、酸価＝２５ｍｇＫＯＨ／ｇ）
・ジ−ｔｅｒｔ−ブチルサリチル酸 １質量部
・エステルワックス（融点＝６５℃） １５質量部
からなる混合物をアトライター（三井金属社製）を用い３時間分散させた後、２，２’−アゾビス（２，４−ジメチルバレロニトリル）３質量部を添加し、重合性単量体組成物を調製した。
【０１４２】
次に、前記水系分散媒体中に該重合性単量体組成物を投入し、内温６５℃のＮ₂雰囲気下で、高速撹拌装置の回転数を１５０００ｒｐｍに維持しつつ、１０分間撹拌し、該重合性単量体組成物を造粒した。その後、撹拌装置をパドル撹拌羽根を具備したものに換え、２００ｒｐｍで撹拌しながら同温度に保持し、重合性ビニル系単量体の重合転化率が９５％に達したところで０．１ｍｏｌ／ＬのＮａＯＨ水溶液を添加して水系分散媒体のｐＨを１０に変更した。更に反応温度を８５℃に昇温し、重合転化率がほぼ１００％になったところで重合反応を完了した。
【０１４３】
重合終了後、加熱減圧下で残存モノマーを留去し、次いで、冷却後に希塩酸を添加して難水溶性分散剤を溶解せしめた。更に水洗浄を数回繰り返した後、円錐型リボン乾燥機（大川原製作所製）を用い、乾燥処理を行い、重合体粒子（Ｙ−１）を得た。
【０１４４】
上記重合体粒子（Ｙ−１）１００質量部とオイル処理シリカ微粉体（ＢＥＴ法比表面積＝２００ｍ²／ｇ）１．２質量部と疎水化処理酸化チタン微粉体（ＢＥＴ法比表面積＝５０ｍ²／ｇ）０．３質量部をヘンシェルミキサー（三井金属社製）で乾式混合してトナー（Ｙ−１）とした。
【０１４５】
該トナー（Ｙ−１）の円相当個数平均径は５．２μｍで、円形度頻度分布における平均円形度は０．９８３、円形度標準偏差は０．０１９であった。また、トナー粒子を構成する結着樹脂成分のＴＨＦの可溶分のＧＰＣにおけるピーク分子量は１．８万で、ＴＨＦ不溶分は２０質量％であった。
【０１４６】
（トナーの製造例２、３）
着色剤として用いた縮合アゾ系顔料とイエロー染料、及びジビニルベンゼン単量体の添加量を変更すると共に、トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｙ−２）と（Ｙ−３）を得た後、トナー（Ｙ−２）と（Ｙ−３）を調製した。
【０１４７】
（トナーの製造例４）
下記混合物をアトライター（三井金属社製）を用い４時間分散し、顔料分散組成物を調製した。

【０１４８】
更に、別容器にて、
・スチレン単量体 ４０質量部
・ｎ−ブチルアクリレート単量体 １７質量部
・ジビニルベンゼン単量体 ０．２質量部
・エステルワックス（融点＝６０℃） ７質量部
からなる混合物に前記顔料分散組成物５７質量部を添加し、６０℃に加温しながら分散、溶解せしめた後、２，２−アゾビス（２，４−ジメチルバレロニトリル）３質量部を添加し、分散質としての重合性単量体組成物を調製した。
【０１４９】
トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｍ−１）を得た後、トナー（Ｍ−１）を調製した。
【０１５０】
（トナーの製造例５〜７）
着色剤として用いたキナクリドン系顔料とモノアゾ系顔料、及びジビニルベンゼン単量体の添加量を変更すると共に、トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｍ−２）〜（Ｍ−４）を得た後、トナー（Ｍ−２）〜（Ｍ−４）を調製した。
【０１５１】
（トナーの製造例８〜１０）
フタロシアニン系着色剤としてＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３を用いると共に、トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｃ−１）〜（Ｃ−３）を得た後、トナー（Ｃ−１）〜（Ｃ−３）を調製した。
【０１５２】
（トナーの製造例１１）
着色剤としてカーボンブラック（平均粒径＝３５ｎｍ）６質量部と荷電制御剤としてモノアゾ系Ｆｅ錯体２質量部を用いると共に、トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｂｋ−１）を得た後、トナー（Ｂｋ−１）を調製した。
【０１５３】
（比較用トナーの製造例１〜３）
着色剤の種類と添加量を変更すると共に、トナー製造時における重合反応時の設定温度、水系分散媒体のｐＨ、及びｐＨ切り替え時の重合転化率を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（ｙ−１）、（ｍ−１）、（ｍ−２）を得た後、トナー（ｙ−１）、（ｍ−１）、（ｍ−２）を調製した。
【０１５４】
（トナーの製造例１２〜１５）
上記重合体粒子（Ｙ−１）、（Ｍ−１）、（Ｃ−１）、及び（Ｂｋ−１）各々１００質量部に、疎水化処理酸化チタン微粉体（ＢＥＴ法比表面積＝２７０ｍ²／ｇ）１．０質量部とオイル処理シリカ微粉体（ＢＥＴ法比表面積＝５０ｍ²／ｇ）０．５質量部をヘンシェルミキサー（三井金属社製）で乾式混合したトナー（Ｙ−１ｂ）、（Ｍ−１ｂ）、（Ｃ−１ｂ）、及び（Ｂｋ−１ｂ）とした後、これらのトナー８質量部に対して樹脂コートキヤリア９２質量部をナウターミキサー（ホソカワミクロン社製）で均一に乾式混合して二成分現像剤（Ｙ−１ｂ）、（Ｍ−１ｂ）、（Ｃ−１ｂ）、及び（Ｂｋ−１ｂ）とした。
【０１５５】
（比較用トナーの製造例４〜５）
上記重合体粒子（ｙ−１）と（ｍ−１）を用いる以外は、前記トナーの製造例１２と同様にして二成分現像剤（ｙ−１ｂ）と（ｍ−１ｂ）を調製した。
【０１５６】
上記トナーの製造例、及び比較用トナーの製造例で用いた着色剤処方、及び得られたトナーの諸性状を表１及び２にまとめて示した。
【０１５７】
【表１】

【０１５８】
【表２】

【０１５９】
〈実施例１〉
図１に示した複数の画像形成部にて各々異なった色のトナー像を形成し、これらを同一転写材上に順次重ね合わせて転写することで多色画像を形成する画像形成方法を用いたフルカラー画像形成装置を用い、第１の画像形成装置ユニットＰａ、第２の画像形成ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄに上記トナーの製造例で得られたトナー（Ｙ−１）、（Ｍ−１）、（Ｃ−１）及び（Ｂｋ−１）を充填し、必要に応じて逐次補給しながら、常温常湿環境下において、各色トナーの印字比率が４面積％となるように作成したテストパターンを用い、転写材として「リサイクルペーパー ＥＮ−１００」（再生パルプの配合率＝１００％）を用い、１６枚／分（Ａ４サイズ紙）のプリントアウト速度で１万枚分のプリントアウト試験を行った。
【０１６０】
尚、定着装置には、分離爪やオフセット防止用液体の塗布機構が配設されていない熱ローラー方式の加熱加圧手段を用いた。加熱ローラーには、アルミニウム製の円筒状の芯金をプライマー処理した後、ジメチルシリコーンゴムの弾性層、更にプライマー層を介して厚さ５０μｍのＰＦＡ製チューブによる表面層を設けたものを用い、一方、加圧ローラーには、ＳＵＳ製の芯金をプライマー処理した後、ジメチルシリコーンゴムの弾性層を設け、更にプライマー層を介して厚さ５０μｍのＰＦＡチューブにより表面層を設けたものを用いた。また、加熱ローラーの円筒状の芯金の内部には加熱体としてハロゲンヒーターを配設し、加熱加圧手段の作動時に定着ローラーの表面温度が１８０℃となるようにし、更に、加熱ローラーと加圧ローラーには２４５Ｎ（２５ｋｇｆ）の当接圧を加え、幅３ｍｍのニップ部が形成されるように設定した。
【０１６１】
得られたプリントアウト画像は、色再現性、細線の再現性、画像耐光性に優れ、初期の状態の色再現性を維持しながらプリントアウト試験を終了した。
【０１６２】
また、プリントアウト画像には画像剥がれ等も発生しておらず、プリントアウト試験終了後、定着装置のローラー表面を目視により評価したところ、トナー付着等の問題はなく、画像形成装置とのマッチングにも優れることがわかった。
【０１６３】
これらの評価結果を表３にまとめて示した。
【０１６４】
〈実施例２〜５〉
各画像形成装置ユニットに上記トナーの製造例で得られた有彩色トナーを順次充填し、必要に応じて逐次補給しながら、実施例１と同様にしてプリントアウト試験を行ったところ、良好な結果を得た。
【０１６５】
これらの評価結果を表３にまとめて示した。
【０１６６】
〈比較例１〉
各画像形成装置ユニットに上記比較用トナーの製造例で得られた比較用の有彩色トナーを順次充填し、必要に応じて逐次補給しながら、実施例１と同様にしてプリントアウト試験を行ったところ、色再現性、細線の再現性、画像耐光性が十分なレベルではなかった。
【０１６７】
また、プリントアウト画像には画像剥がれ等の問題が発生しており、プリントアウト試験中に定着装置のローラー表面にプリントアウト画像が巻き付く等の現象が見られた。
【０１６８】
これらの評価結果を表３にまとめて示した。
【０１６９】
〈比較例２、３〉
各画像形成装置ユニットに上記比較用トナーの製造例で得られた比較トナー順次を充填し、必要に応じて逐次補給しながら、実施例１と同様にしてプリントアウト試験を行ったところ、色再現性、細線の再現性、画像耐光性、画像剥がれ、及び定着装置とのマッチング等が十分なレベルではなかった。
【０１７０】
これらの評価結果を表３にまとめて示した。
【０１７１】
〈実施例６〉
第１の画像形成装置ユニットＰａ、第２の画像形成ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄの各々を二成分接触現像用に改造し、上記トナーの製造例で得られた二成分現像剤（Ｙ−１ｂ）、（Ｍ−１ｂ）、（Ｃ−１ｂ）及び（Ｂｋ−１ｂ）を充填し、必要に応じてトナー（Ｙ−１ｂ）、（Ｍ−１ｂ）、（Ｃ−１ｂ）及び（Ｂｋ−１ｂ）を逐次補給しながら、実施例１と同様にしてプリントアウト試験を行った。
【０１７２】
得られたプリントアウト画像は、色再現性、細線の再現性、画像耐光性に優れ、初期の状態の色再現性を維持しながらプリントアウト試験を終了した。
【０１７３】
また、プリントアウト画像には画像剥がれ等も発生しておらず、プリントアウト試験終了後、定着装置のローラー表面を目視により評価したところ、トナー付着等の問題はなく、画像形成装置とのマッチングにも優れることがわかった。
【０１７４】
これらの評価結果を表３にまとめて示した。
【０１７５】
〈比較例４〉
第１の画像形成装置ユニットＰａ、第２の画像形成ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄの各々を二成分接触現像用に改造し、上記トナーの製造例、及び比較用トナーの製造例で得られた二成分現像剤（ｙ−１ｂ）、（ｍ−１ｂ）、（Ｃ−１ｂ）及び（Ｂｋ−１ｂ）を充填し、必要に応じてトナー（ｙ−１ｂ）、（ｍ−１ｂ）、（Ｃ−１ｂ）及び（Ｂｋ−１ｂ）を逐次補給しながら、実施例６と同様にしてプリントアウト試験を行ったところ、色再現性、細線の再現性、画像耐光性、画像剥がれ及び定着装置とのマッチング等が十分なレベルではなかった。
【０１７６】
これらの評価結果を表３にまとめて示した。
【０１７７】
【表３】

【０１７８】
上記実施例及び比較例中に記載の評価項目の説明とその評価基準について述べる。
【０１７９】
［プリントアウト試験］
〈１〉普通紙上の色空間体積
通常の複写機用普通紙（７５ｇ／ｍ²）上に得られたフルカラー画像を「スペクトロホトメーターＳＰ６８」（Ｘ−Ｒｉｔｅ社製）で測色することによって、国際照明委員会（ＣＩＥ）で規格されたＬ^*ａ^*ｂ^*表色系の明度Ｌ^*、赤〜緑の度合いを表すａ^*、及び黄〜青の度合いを表すｂ^*で決定される色空間立体を決定し、その色空間立体の体積を求めた。色空間立体の体積（数値）が大きい程、良好な色再現性を有することになる。
Ａ：２５０万以上
Ｂ：２００万以上、２５０万未満
Ｃ：１５０万以上、２００万未満
Ｄ：１５０万未満
【０１８０】
〈２〉細線の再現性
グラフィカルな画像の画質や階調性に関わる評価であり、図２に示すようなプリントアウト画像の細線の再現性を評価した。
Ａ：良好な細線の再現性を示す
Ｂ：軽微な細線の幅の変動が見られる
Ｃ：細線の細りや飛び散りが目立つ
Ｄ：所々で細線の断裂が見られ、再現性に劣る
【０１８１】
〈３〉投影画像の色再現性
トランスペアレンシーフィルム上に得られたフルカラー画像をオーバーヘッドプロジェクター「ＯＨＰ ９５５０」（３Ｍ社製）により透過画像とし、該透過画像を白色スクリーンに投影して得られた投影画像の２次色部分（赤色：イエロー５０％／マゼンタ５０％、緑色：シアン５０％／イエロー５０％、青色：マゼンタ５０％／シアン５０％）を目視により評価すると共に、分光放射輝度計（フォトリサーチ社製）で測色し、Ｌ^*ａ^*ｂ^*表色系で示される色空間立体を決定し、その色空間立体の体積を求めた。
【０１８２】
２次色部分の目視評価
Ａ：２次色（赤色、青色）の色再現性も鮮やかで、且つ透明性に優れる
Ｂ：１次色の色再現性や透明性に優れるが、２次色の再現性にやや劣る
Ｃ：１次色の色再現性や透明性にやや劣る
Ｄ：１次色の色再現性に劣り、クスミを生じる
【０１８３】
色空間立体の体積
Ａ：２５０万以上
Ｂ：２００万以上、２５０万未満
Ｃ：１５０万以上、２００万未満
Ｄ：１５０万未満
【０１８４】
〈４〉画像剥がれ
やや厚めの転写紙（１０５ｇ／ｍ²、Ａ４サイズ）上にトナー量が０．８ｍｇ／ｃｍ²程度となるようにベタ画像を作成し、得られた画像表面の画像剥がれの発生状況を目視により評価した。画像剥がれの箇所が少ない程、発生が抑制されたことになる。
Ａ：未発生
Ｂ：１箇所以上、５箇所以下
Ｃ：６箇所以上、１０箇所以下
Ｄ：１１箇所以上（或いは、直径２ｍｍ以上の画像剥がれが発生）
【０１８５】
〈５〉画像耐光性
転写紙上のトナー量が０．６ｍｇ／ｃｍ²程度のベタ画像を作成し、カーボンアークランプを光源とした紫外線オートフェードメーター「ＦＡＬ−ＡＵ」（スガ試験機社製）を用い、「ＪＩＳ Ｋ ７１０２」に準じて評価した。最大照射時間を２４０時間とし、光照射前後の画像濃度の維持率を算出し、画像の耐光性を評価した。画像濃度維持率（％）が１００％に近い程、画像耐光性に優れることになる。
Ａ：９０％以上
Ｂ：８０％以上、９０％未満
Ｃ：６５％以上、８０％未満
Ｄ：６５％未満
【０１８６】
［定着器とのマッチング評価］
プリントアウト試験終了後、加熱ローラーへの残留トナーの固着の様子とプリントアウト画像への影響を目視で評価した。
Ａ：トナーの固着は未発生
Ｂ：紙粉による汚染や端部へのトナーの固着が見られたが、定着画像への影響は軽微である
Ｃ：紙粉による汚染や端部へのトナーの固着によりプリントアウト画像の裏面に軽微なトナー汚れが発生しているものの、定着画像への影響は殆ど見られない
Ｄ：トナー固着による定着画像への影響やプリントアウト試験中にプリントアウト画像の巻き付きが発生
【０１８７】
【発明の効果】
以上説明したように、本発明によれば、複数の画像形成部にて各々異なった色のトナー像を形成し、これらを同一転写材上に順次重ね合わせて転写することで多色画像を形成する画像形成方法を用いた画像形成装置に、着色剤を特定した有彩色現像剤と黒色現像剤からなるカラー画像形成用現像剤キットを用いることで、広範囲の色再現を達成した高精細で高解像度のフルカラー画像形成がなされると共に、十分な画像耐光性を達成し、更にはオフセット防止用液体を用いない定着装置に適応した場合にも、定着装置の定着ローラー等の定着部材表面にトナーが付着残余することを未然に防止することが出来るので、多数枚プリントアウト時においても良好な色再現を安定して得ることが出来る。
【図面の簡単な説明】
【図１】本発明の実施例に用いたフルカラー画像形成装置の概略的説明図である。
【図２】細線の再現性を評価する為のライン画像の説明図である。
【符号の説明】
１５ａ 現像ローラー
１７ａ、１７ｂ、１７ｃ、１７ｄ 現像装置
１９ａ、１９ｂ、１９ｃ、１９ｄ 感光体ドラム
２０ 転写材担持体
２３ 定着器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chromatic development of at least three colors of at least a yellow developer, a magenta developer, and a cyan developer used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet method, or the like. The present invention relates to a color image forming developer kit composed of an agent and an image forming method using the color image forming developer kit.
[0002]
More particularly, the present invention relates to a color image forming developer kit used in a color image recording apparatus that can be used in a copying machine, a printer, a facsimile, a plotter, and the like, and an image forming method using the color image forming developer kit. .
[0003]
[Prior art]
Conventionally, electrophotographic methods are known in a number of ways as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is developed with toner, and if necessary, a direct or indirect means is used to make paper. After the toner image is transferred to such a transfer material, it is fixed by heating, pressing, heating and pressing, or solvent vapor to obtain a fixed image. Further, in the case of having a step of transferring the toner image, a step for removing the transfer residual toner on the photoreceptor is usually provided, and the above-described steps are repeated.
[0004]
Particularly in full-color image formation, an electrostatic latent image is generally composed of a chromatic developer composed of magenta (M) toner, cyan (C) toner, yellow (Y) toner, and the like, and black (Bk) toner. A multicolor image is reproduced by developing with a black developer and superimposing toner images of respective colors. Japanese Patent Publication Nos. 49-46951, 50-776, 53-47147, 53. -47175, 53-47176, and the like.
[0005]
In recent years, the field of application of an image forming apparatus using the electrophotographic method as described above is not only a copying machine for copying an original document, but also a printer as a computer output or a personal copy for an individual, It is rapidly developing to plain paper fax machines, and various demands are increasing. In addition, copying machines are becoming more sophisticated due to digitalization. In particular, downsizing, speeding up, and multi-coloring of the image forming apparatus are remarkable, and there is a strong demand for high reliability and high resolution.
[0006]
In response to the above demands, an image forming method is used in which a plurality of image forming portions form toner images of different colors, and these are sequentially transferred on the same transfer material to form a multicolor image. The full-color image forming apparatus has been widely used.
[0007]
FIG. 1 is a schematic explanatory view of a full-color image forming apparatus using an image forming method for forming a multicolor image as described above.
[0008]
The full-color image forming apparatus main body is provided with a first image forming apparatus unit Pa, a second image forming apparatus unit Pb, a third image forming apparatus unit Pc, and a fourth image forming apparatus unit Pd. The toner images of different colors are formed on the transfer material by repeating the steps (a) charging step, (b) exposure step, (c) development step, (d) transfer step, and (e) cleaning step. It is formed.
[0009]
In the image forming apparatus as described above, it is effective to increase the transferability and resistance to mechanical stress from the apparatus by making the toner particle shape spherical, but the specific surface area and volume of the toner particles are reduced. As a result, the dispersibility of the colorant inside the toner particles has an unexpected influence on the matching with the fixing device.
[0010]
Generally, a fixing device for fixing a toner image is of a heat roller type using a heating roller as a rotary heating member and a pressure roller as a rotary pressure member (hereinafter referred to as a fixing roller together). Although a heat fixing unit is used, when image formation is performed at a higher speed, a large amount of heat energy is instantaneously required while applying a high pressure. For this reason, unfavorable situations such as an increase in the size of the fixing device and a long preheating time at start-up have occurred. From these viewpoints, the toner used in the image forming apparatus as described above preferably exhibits a high sharp melt property when heated. Further, such a toner is excellent not only in low-temperature fixability but also in color mixing at the time of full-color image formation, so that it is possible to widen the color reproduction range of the obtained fixed image.
[0011]
However, since the toner as described above generally has high affinity with the fixing roller, it tends to cause an offset phenomenon in which the toner is transferred to the surface of the fixing roller at the time of fixing, and in particular, yellow toner, magenta toner, This occurs remarkably during color image formation in which a plurality of toner layers are formed of cyan toner and black toner.
[0012]
On the other hand, for the purpose of preventing the toner from adhering to the surface of the fixing roller, for example, the surface material of the fixing roller is further offset by using a material having excellent releasability from toner such as silicone rubber and fluorine resin. In order to prevent the phenomenon and the deterioration of the surface of the fixing roller, the surface of the fixing roller is coated with a thin film of an anti-offset liquid.
[0013]
However, although the method as described above is extremely effective in preventing the offset phenomenon, (1) since a device for supplying the liquid for preventing offset is necessary, the fixing device becomes complicated, and is small and inexpensive. (2) The applied anti-offset liquid soaks into the fixing roller during heating and induces delamination between the layers constituting the fixing roller. As a result, the life of the fixing roller is shortened. (3) Since the liquid for preventing offset adheres to the obtained fixed image, a sticky feeling is produced, or a transparency film used for an overhead projector, particularly for a presentation. When used as a transfer material, the transparency is impaired, so the desired color reproducibility cannot be obtained. (4) Offset prevention liquid There was a technical problem that contaminate the inside of the image forming apparatus, resulting in negative effects like.
[0014]
On the other hand, transfer materials used in the image forming apparatus as described above are also diversified. For example, as the type of paper used as a transfer material, not only the difference in weighing but also the material and content of raw materials and fillers are different at present. Among these transfer materials, there are various quality of transfer materials, such as those in which the constituent materials are easily detached and those that are easily attached to the constituent members of the fixing device. The fixing device is greatly affected by these transfer materials, and it is difficult to reduce the size and extend the life of the fixing device.
[0015]
In addition, the contaminants and toner derived from the transfer material are agglomerated and fixed on the fixing roller, causing a problem that the performance of the fixing device is deteriorated, and the quality of the fixed image is deteriorated due to peeling of the fixed matter. It was.
[0016]
Specifically, recycled paper using recycled pulp obtained by deinking paper once used has been widely used from the viewpoint of environmental protection and the like. However, recycled paper often contains various contaminants. For example, JP-A-3-28789, JP-A-4-65596, JP-A-4-147152, JP-A-5-110145. As disclosed in Japanese Patent Application Laid-Open No. 6-35221 and the like, in order to enable use in the image forming apparatus as described above, the content and configuration of impurities in the recycled paper are set. Need to be identified.
[0017]
Currently, recycled paper used in general offices has a ratio of recycled pulp such as used newspapers exceeding 70%, and the amount of recycled paper is expected to increase in the future, causing the above problems. Is concerned. Further, when a cleaning member for removing toner remaining on the fixing surface or a separating member for preventing the transfer material from being wound is provided on the surface of the heating roller, it is particularly preferable to use medium-sized waste paper such as newspapers and magazines as a raw material. It has been confirmed that the surface of the fixing roller is damaged or scraped by the medium pulp fibers contained in the paper powder detached from the recycled paper, and the functions of the cleaning member and the separating member are remarkably deteriorated. The phenomenon as described above tends to become a serious problem when a fixing device in which the application amount of the liquid for preventing offset to the fixing roller is small or a fixing device in which the liquid for preventing offset is not applied is used.
[0018]
As described above, it is very useful to apply the offset preventing liquid to the surface of the fixing roller of the fixing device, but it has various problems.
[0019]
Considering the recent demands of image forming apparatuses such as miniaturization and weight reduction and the quality of fixed images obtained, it is preferable to remove even the auxiliary apparatus for applying the liquid for preventing offset.
[0020]
Under such circumstances, technical development relating to heat and pressure fixing of toner is essential, and several measures have been proposed for these.
[0021]
Conventionally, a number of methods for adding a wax component such as low molecular weight polyethylene or polypropylene to the toner have been proposed in consideration of supplying the offset preventing liquid from the toner during heating without using an offset preventing liquid supply device. Yes. However, in order to achieve a sufficient effect, it is necessary to add a large amount of the wax component as described above to the toner. In this case, filming on the photoconductor or contamination of the surface of the toner carrier such as a carrier or sleeve Cause new problems such as image degradation. In addition, when the amount of the wax component added is small, it is necessary to provide a device for supplying a small amount of offset preventing liquid, or an auxiliary cleaning member such as a take-up type cleaning web or a cleaning pad. Arise. In particular, when a transparency film is used as a transfer material during full-color image formation, transparency of the fixed image and haze (cloudiness) are caused by high crystallization of the wax component and a difference in refractive index from the binder resin. The problem of worsening remains unresolved.
[0022]
Also, JP-B-52-3304, JP-B-52-3305, JP-A-57-52574, JP-A-60-217366, JP-A-60-252360, JP-A-60- No. 252361, JP-A 61-94062, JP-A 61-138259, JP-A 61-273554, JP-A 62-14166, JP-A 1-109359, JP Japanese Patent Application Laid-Open No. 2-79860 and Japanese Patent Application Laid-Open No. 3-50559 disclose techniques for including a wax component in the toner, but various properties required for the toner are obtained simply by adding the wax component to the toner. It is difficult to improve the image quality to a high degree, and matching with an image forming apparatus using a heat and pressure fixing method is not sufficient.
[0023]
Incidentally, it is known in the technical field to use various pigments and dyes as colorants for the purpose of improving the color reproducibility of a color toner image.
[0024]
In particular, magenta toner is not only important for reproducing red with high human visual sensitivity with yellow toner, but also has excellent developability when reproducing the flesh color of human images with complex tones, for example. Required. In addition, cyan toner must be able to achieve secondary color reproduction of blue, which is frequently used as a business color.
[0025]
Conventionally, quinacridone colorants, thioindigo colorants, xanthene colorants, monoazo colorants, perylene colorants, diketopyrrolopyrrole colorants, etc. are used alone or in combination for magenta toners. It is known.
[0026]
For example, JP-B-49-46951 discloses 2,9-dimethylquinacridone pigment, JP-A-55-26574 discloses thioindigo pigment, JP-A-59-57256 discloses xanthene dye, JP-A-11 JP-A-272014 proposes a toner using a monoazo pigment, JP-A-2-210259 discloses a diketopyrrolopyrrole pigment, and JP-B-55-42383 discloses an anthraquinone pigment.
[0027]
However, these colorants do not satisfy all conditions required for magenta toner, and there is room for improvement in toner color tone, light resistance, charging characteristics, and matching with an image forming apparatus. Was leaving.
[0028]
In JP-A-1-22477, a quinacridone organic pigment and a xanthene dye are used in combination, and in JP-A-2-13968, a quinacridone-type and methine-type colorant are used in combination to obtain a clear magenta toner. Further, a method for improving the chargeability and light resistance of toner and preventing dyeing on a fixing roller such as a silicone rubber roller is disclosed. Further, Japanese Patent Laid-Open No. 62-291669 (corresponding US Pat. No. 4,777,105) proposes a toner using a mixed crystal quinacridone pigment.
[0029]
On the other hand, in JP-A-11-52625, C.I. I. Pigment Red Class 48 red pigments and L^*a^*b^*B in the color system^*When a red pigment such as a cridon pigment having a value of −5 or less is used in combination at a mixing ratio of 2 to 30% by weight with respect to all pigments, a good magenta color toner can be obtained. A method for improving the light resistance and further improving the heat resistance of the fixing roller is disclosed.
[0030]
On the other hand, it is known to use a monoazo yellow colorant, a benzimidazolone colorant, a disazo yellow colorant, or the like alone or as a mixture for the yellow toner.
[0031]
For example, JP-A-8-262799 discloses C.I. I. A method for improving image light resistance while preventing image scattering and image fogging by using a benzimidazolone colorant typified by Pigment Yellow 180 or the like is disclosed.
[0032]
However, the toner described above hardly takes into account the influence of the colorant on the heat fixing method, and according to the knowledge of the present inventors, reaggregation easily occurs in the toner particles. When toner particles are produced by the above, the tendency becomes remarkable. In addition, when recycled paper with a recycled pulp content of more than 70% is used as a transfer material, or when a plurality of toner layers formed on the transfer material must be fixed at one time, or to a fixing roller No consideration is given to the case of using a fixing device with a small amount of application of the liquid for preventing offset, or a fixing device without application of the liquid for preventing offset.
[0033]
In JP 2000-75554 A and JP 2000-105485 A, C.I. I. A method for improving color reproducibility and image light fastness by using a yellow dye-based colorant typified by Solvent Yellow 162 or the like is disclosed. Further, JP 2000-75552 A discloses C.I. I. Toner using a condensed azo colorant typified by Pigment Yellow 93 and the like, and JP-A 2000-75552 discloses a toner using the condensed azo colorant and the yellow dye colorant in combination. Yes. Although the above toner has been improved with respect to the effects on color reproducibility and heat fixing method, it does not satisfy all the conditions required for reproducing a full color image, and particularly with magenta toner. There remains room for improvement in red reproducibility corresponding to the secondary color and matching with the image forming apparatus at that time.
[0034]
As mentioned above, regarding the system design of the color image forming apparatus using the heat fixing method, there is not yet sufficient comprehensive comprehensive correspondence including the colorant used for the toner.
[0035]
[Problems to be solved by the invention]
An object of the present invention is to provide a developer kit for forming a color image that solves the problems of the related art, and an image forming method using the developer kit for forming a color image.
[0036]
That is, the object of the present invention is to stably realize a high-quality image excellent in color reproducibility and fine line reproducibility over a long period of time, achieve sufficient image light resistance, and, in particular, an electrophotographic process, It has excellent characteristics that make it highly applicable when forming a color image where multiple toner layers formed on a transfer material must be fixed at once, or when using a fixing device with a small amount of liquid for preventing offset. The object is to provide a color image forming developer kit and an image forming method using the color image forming developer kit.
[0037]
[Means for Solving the Problems]
In view of the above, the present inventors have formed a multi-color image by forming toner images of different colors in a plurality of image forming sections and transferring them in sequence on the same transfer material. In the method, by specifying the type and blending amount of the colorant contained in the toner particles in the chromatic developer constituting the color image forming developer kit used in the image forming method, a high quality image can be obtained. The present invention has been completed by realizing that it can be stably realized over a long period of time and can be applied to an electrophotographic process at a high level.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the present invention.
[0039]
A developer kit for color image formation according to the present invention is a developer kit for color image formation composed of at least three chromatic color developers including a yellow developer, a magenta developer, and a cyan developer. Each chromatic developer has toner particles and inorganic fine powder containing at least a binder resin, a colorant, and a wax component.
[0040]
The yellow toner particles in the yellow developer include a condensed azo pigment represented by the following structural formula (1) and C.I. I. Solvent Yellow 9, 17, 24, 31, 35, 58, 93, 100, 102, 103, 105, 112, 162, 163, C.I. I. Disperses Yellow 42, 64, 82, 160, 201, and 224 selected from the group of yellow dyes (each according to the name described in Color Index 4th edition), and the total content is 1 It is prepared so that the mass ratio of the content is ˜20% by mass, and the condensed azo pigment: monoazo dye = 25: 75 to 75:25.
[0041]
[Chemical 7]

[0042]
By containing the above-mentioned condensed azo pigment and yellow dye in a specific ratio in the yellow toner particles, not only the dispersion state of the colorant in the toner particles is improved, but the characteristics of the yellow toner itself are improved. A good full-color image can be obtained by a combination with a magenta developer or a cyan developer described later.
[0043]
In particular, the condensed azo pigments used are C.I. I. Pigment Yellow 93, 94, 95, 128, and 166, and the yellow dye is C.I. I. Solvent Yellow 93, 105, 112, 162, 163, C.I. I. In the case of any one selected from the group of Dispers Yellow 42, 64, 160, and 201 (each according to the name described in the color index fourth edition), the improvement effect becomes even better.
[0044]
The magenta toner particles in the magenta developer contain a quinacridone pigment represented by the following structural formula (2) and a monoazo pigment represented by the following structural formula (3), and the total content thereof is 1 to 20% by mass. The mass ratio of the content is prepared so that the quinacridone pigment: monoazo pigment = 25: 75 to 75:25.
[0045]
[Chemical 8]

[X₁And X₂Represents a hydrogen atom or a substituent selected from an alkyl group, an alkoxy group, and a halogen group. ]
[0046]
[Chemical 9]

[0047]
Also in the magenta toner particles, by adding the quinacridone pigment and the monoazo pigment as described above in a specific ratio, the dispersion state of the colorant in the toner particles is improved, and the characteristics of the magenta toner itself are improved. In addition, a good full-color image can be obtained by the combination with the yellow developer and the cyan developer as described above.
[0048]
In particular, the quinacridone pigment used is C.I. I. Pigment Red 122, 202, C.I. I. Pigment Violet 19 and / or a solid solution pigment thereof, and the monoazo pigment is C.I. I. Pigment Red 5, selected from the group of 31, 31, 146, 147, 150, 176, 184, 185, or 269 (each according to the name described in the color index 4th edition) The improvement effect becomes even better.
[0049]
The cyan toner particles of the cyan developer contain a phthalocyanine pigment and are prepared so that the content thereof is 1 to 10% by mass. In particular, phthalocyanine pigments used for cyan developer toner particles are C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, and 16 (each according to the name described in the color index 4th edition), A good full-color image can be obtained by a combination with the above-described magenta developer or yellow developer.
[0050]
By specifying the type and content of the colorant in the toner particles as described above, it becomes possible to improve the colorant content state in the toner particles and achieve high-definition and high-resolution that achieves faithful color reproduction. Full color image formation is performed. In addition, even when using a fixing device with a small amount of anti-offset liquid applied to the fixing roller when forming a color image where a plurality of toner layers must be fixed at the same time, By suppressing the influence of the colorant to a minimum, it is possible to prevent toner from adhering and remaining on the surface of the fixing member such as a fixing roller of the fixing device. The inventors have found that color reproduction can be stably obtained, and have completed the present invention.
[0051]
The developer kit for color image formation according to the present invention is not limited to the three chromatic developers such as yellow developer, magenta developer, and cyan developer, but other chromatic developers and black developers for the purpose of color tone adjustment. Agents can be added to the composition. In addition, the toner particles according to the present invention can be used alone or in combination with a solid solution other than the colorant as described above within a range that does not adversely affect the toner characteristics.
[0052]
As the black colorant for the black developer, carbon black, a magnetic material, or a mixture of the above-described yellow colorant / magenta colorant / cyan colorant mixed with black can be used.
[0053]
The carbon black preferably used in the present invention has a nitrogen adsorption specific surface area of 100 m.²/ G or less, and the nitrogen adsorption specific surface area is 100 m.²If it exceeds / g, it will be difficult to disperse in the toner, which will cause problems with the chargeability and coloring power of the toner. In addition, when a toner is produced by a polymerization method, it affects the polymerizability of the monomer and is not suitable for use.
[0054]
In addition, the measurement of the nitrogen adsorption specific surface area of carbon black is performed based on "ASTM D3037-79".
[0055]
The toner particles in the developer according to the present invention have a circle-equivalent number average diameter D1 (μm) of 2 to 10 μm and an average in a number-based circle-equivalent diameter-circularity scattergram measured by a flow particle image measuring device. The circularity is 0.950 to 0.995, the circularity standard deviation is less than 0.040, and the main component of the binder resin is a styrene- (meth) acrylic resin, and the tetrahydrofuran of the binder resin The particle shape of the toner particles and the binder resin component are adjusted so that the peak molecular weight in gel permeation chromatography (GPC) of the soluble part of (THF) is 5000 to 30,000 and the THF insoluble part is 5 to 35% by mass. By controlling precisely, toner characteristics can be improved in a well-balanced manner.
[0056]
That is, by reducing the particle equivalent number average diameter D1 (μm) of the toner particles to 2 to 10 μm, and more preferably 3 to 6 μm, the image is reproduced by developing an outline portion, particularly a character image or a line pattern. The property is good.
[0057]
In general, when the toner particle size is reduced, the presence rate of fine toner particles inevitably increases, so that it is difficult to uniformly charge the toner and image fogging occurs, and matching with the image forming apparatus is also hindered. Was invited.
[0058]
However, in the developer according to the present invention, the average circularity of the circularity frequency distribution of the toner particles is 0.950 to 0.995, preferably 0.965 to 0.995, more preferably 0.975 to 0.990. As a result, the transferability of a toner having a small particle diameter, which has been difficult in the past, is greatly improved and the developing ability for a low potential latent image is remarkably improved. In particular, the above-mentioned tendency is very effective when developing a digital microspot latent image or when forming a full-color image that is transferred many times using an intermediate transfer member, and also has good matching with an image forming apparatus. It will be something.
[0059]
Further, the developer according to the present invention has a circularity standard deviation of the circularity frequency distribution of the toner particles by less than 0.040, preferably less than 0.035, more preferably 0.015 or more and less than 0.030. When the toner thin layer is formed on the toner carrying member, the toner charge amount can be made appropriate, and the above-described problems can be greatly improved.
[0060]
By the way, in general, when a toner exhibiting a specific particle size distribution or shape distribution as described above is used, a toner particle slip-through phenomenon occurs when a thin layer of toner is formed on the surface of the toner carrier, and the image deterioration often occurs. May cause. However, in the toner of the present invention, by specifying the type and content of the colorant contained in the toner particles, the dispersion state of the colorant in the toner particles can be improved, and the charge application to the toner can be performed rapidly. Since it can be performed uniformly, it is possible to prevent image deterioration as described above.
[0061]
The equivalent-circle diameter, circularity, and frequency distribution of the toner in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow-type particle image measuring device “ Measurement was carried out using "FPIA-1000 type" (manufactured by Toa Medical Electronics Co., Ltd.), and calculation was performed using the following formula.
[0062]
[Expression 1]

[0063]
Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.
[0064]
The circularity in the present invention is an index indicating the degree of unevenness of toner particles, and is 1.000 when the toner particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated.
[0065]
In the present invention, the circle-equivalent number average diameter D1 (μm) and the particle size standard deviation SDd, which mean the average value of the particle number frequency distribution based on the number of toners, are the particle size (central value) at the dividing point i of the particle size distribution. Is di, and the frequency is fi.
[0066]
[Expression 2]

[0067]

[0068]
[Equation 3]

[0069]
As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a dispersion means, an ultrasonic disperser “UH-50 type” (manufactured by SMT Co., Ltd.) equipped with a 5φ titanium alloy chip as a vibrator is used and subjected to a dispersion treatment for 5 minutes to obtain a dispersion for measurement. . In that case, it cools suitably so that the temperature of this dispersion may not become 40 degreeC or more.
[0070]
To measure the shape of the toner particles, the flow type particle image measuring device is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 particles / μL, and 1000 toner particles are obtained. Measure above. After the measurement, this data is used to obtain the equivalent circle diameter, circularity frequency distribution, etc. of the toner particles.
[0071]
In addition, since the specific surface area of the toner particles according to the present invention is reduced by controlling the particle shape as described above, the effect of specifying the type and content of the colorant contained in the toner particles is remarkable. Become.
[0072]
Examples of the binder resin used for the toner particles of the developer according to the present invention include commonly used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins, and styrene-butadiene copolymers. In particular, a styrene- (meth) acrylic resin as a main component is preferable from the viewpoint of the affinity with the colorant as described above. Further, the toner particles have a peak molecular weight in the gel permeation chromatography (GPC) of the soluble content of tetrahydrofuran (THF) of the binder resin of 5000 to 30,000 and the THF insoluble content of 5 to 35% by mass. By precisely controlling the particle shape and the binder resin component, the toner characteristics can be improved in a well-balanced manner.
[0073]
In the present invention, GPC of the THF-soluble component of the binder resin component is measured under the following conditions. In addition, the sample is used after being dispersed / dissolved in a solvent for 12 hours or more and then filtered through a solvent-resistant membrane filter (pore diameter: 0.45 μm).
[0074]

[0075]
In the present invention, the THF-insoluble content of the binder resin indicates the mass ratio of the resin component insoluble in THF in the resin composition in the toner particles, and indicates the degree of crosslinking of the resin composition containing the crosslinking component. As a guide, even if the THF-insoluble content is 0% by mass, it does not necessarily mean that it is not crosslinked. The THF-insoluble content is defined as a value measured as follows.
[0076]
That is, the toner particles are weighed in the range of 0.5 to 1.0 g (W₁g), put into “cylindrical filter paper No. 86R” (manufactured by Toyo filter paper), set as it is in a Soxhlet extractor, and extract with 100 to 200 ml of THF for 20 hours. The soluble component extracted with THF is then recovered and its mass (W₂g). On the other hand, among other components such as pigments contained in the toner particles, the mass (W_Threeg) and mass of insoluble component (W_Fourg) is separately measured by a known method, and the THF-insoluble content of the binder resin in the toner particles is calculated according to the following formula.
[0077]
[Expression 4]

[0078]
In a method for directly obtaining toner particles by a polymerization method, a monomer for forming them is used. Specifically, styrene; styrene monomers such as o- (m-, p-) methylstyrene, m- (p-) ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as dimethylaminoethyl acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide Preferably used. These may be used alone or in general so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-P139-192 (John Wiley & Sons) is 40-75 ° C. It is used by appropriately mixing the monomer. When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur in terms of storage stability and durability stability of the toner, while when it exceeds 75 ° C., the toner fixing point is increased, and the fixability and color reproduction are increased. It causes sexual deterioration.
[0079]
Furthermore, in the present invention, it is preferable to use a crosslinking agent during the synthesis of the binder resin in order to increase the mechanical strength and color reproducibility of the toner particles.
[0080]
Examples of the crosslinking agent used in the toner according to the present invention include divinylbenzene, bis (4-acryloxypolyethoxyphenyl) propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, , 4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 200, # 400, # 600 diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester type diacrylate (M NDA Nippon Kayaku), and those obtained by changing the methacrylates of the above diacrylate.
[0081]
Polyfunctional crosslinkers include pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate and its methacrylate, 2,2-bis (4-methacryloxy, polyethoxy Phenyl) propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and triallyl trimellitate.
[0082]
These cross-linking agents are preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of other vinyl monomers.
[0083]
In the present invention, a resin having polarity (hereinafter referred to as “polar resin”) such as a polyester resin and a polycarbonate resin can be used in combination with the above-described binder resin. By adding a polar resin to the toner, it is easy to make the colorant content in the toner particles favorable.
[0084]
For example, when a toner is directly produced by a suspension polymerization method, which will be described later, when a polar resin as described above is added during the polymerization reaction from the dispersion step to the polymerization step, a polymerizable monomer composition that becomes toner particles and Depending on the balance of polarity exhibited by the aqueous dispersion medium, the added polar resin can be controlled so as to form a thin layer on the surface of the toner particles or to have a gradient from the toner particle surface toward the center. At this time, by using a polar resin that interacts with the colorant according to the present invention, it is possible to make the presence state of the colorant in the toner particles into a desirable form, and particularly an acid value of 1 to 40 mgKOH. It is preferable to use a polar resin exhibiting / g.
[0085]
The addition amount of the polar resin is preferably 1 to 25 parts by mass, more preferably 2 to 15 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 1 part by mass, the presence state of the polar resin in the toner particles becomes non-uniform. Conversely, if the amount exceeds 25 parts by mass, the thin layer of the polar resin formed on the toner particle surface becomes thick. It becomes difficult to control the content of the colorant, and the function cannot be fully expressed.
[0086]
The polar resins as described above are not limited to one type of polymer. For example, two or more types of reactive polyester resins can be used simultaneously, or two or more types of vinyl polymers can be used. In addition, completely different types of polymers, such as non-reactive polyester resins, epoxy resins, polycarbonate resins, polyolefins, polyvinyl acetate, polyvinyl chloride, polyalkyl vinyl ethers, polyalkyl vinyl ketones, polystyrenes, poly (meth) acrylic esters Various polymers such as melamine formaldehyde resin, polyethylene terephthalate, nylon and polyurethane can be added to the binder resin as necessary.
[0087]
Specific examples of the wax component that can be used in the present invention include petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof according to the Fischer-Tropsch method. , Polyolefin waxes typified by polyethylene and derivatives thereof, natural waxes such as carnauba wax and candelilla wax, and derivatives thereof, and the like include oxides, block copolymers with vinyl monomers, and graft modified products. Is also included. Further, alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes. These can be used alone or in combination.
[0088]
Among these, when polyolefin, Fischer-Tropsch hydrocarbon wax, petroleum wax, higher alcohol, or higher ester is used, the effect of improving developability and transferability is further enhanced. These wax components may be added with an antioxidant within a range that does not affect the chargeability of the toner. Moreover, it is preferable to use 1-30 mass parts of these wax components with respect to 100 mass parts of binder resin.
[0089]
The wax component used in the present invention has a main endothermic peak temperature (melting point) in a DSC curve measured according to “ASTM D3418-82” of 30 to 150 ° C., more preferably 40 to 120 ° C., particularly preferably 50. Compounds in the range of ~ 90 ° C are preferred.
[0090]
By using the wax component exhibiting the thermal characteristics as described above, not only good fixability of the obtained toner, but also the release effect by the wax component is efficiently expressed, and a sufficient fixing area is ensured. In addition to obtaining a color image exhibiting excellent color reproducibility, it is possible to eliminate developability, blocking resistance and adverse effects on the image forming apparatus due to conventionally known wax components. In particular, since the specific surface area of the toner decreases as the toner particle shape becomes spherical, it is very effective to control the thermal characteristics and dispersion state of the wax component.
[0091]
For example, “DSC-7” (manufactured by Perkin Elmer) is used for measuring the main endothermic peak temperature (melting point) of the wax component. The melting point of iridium and zinc is used for temperature correction of the device detection unit, and the heat of fusion of iridium is used for correction of heat quantity. In the measurement, a sample in which the measurement sample was put in an aluminum pan and an aluminum pan only (empty pan) were set for the control, and the measurement range of 20 to 180 ° C. was increased at a heating rate of 10 ° C./min. The main endothermic peak temperature (melting point) is determined from the DSC curve obtained when warmed. When only the wax component is measured, the measurement is started after the temperature is raised and lowered under the same conditions as the measurement and the previous history is removed. When measuring the wax component contained in the toner, the measurement is performed as it is without performing the operation of removing the previous history.
[0092]
The toner particles according to the present invention can be used in combination with a known charge control agent for the purpose of finely adjusting the triboelectric charge amount and the charge speed. In particular, the charge speed is fast and a constant charge amount is stable. A charge control agent that can be maintained as such is preferred. Further, when the toner particles are produced by a direct polymerization method, a charge control agent that does not inhibit polymerization and has no solubilized product in an aqueous dispersion medium is preferable. Specific compounds include, as negative charge control agents, metal compounds of carboxylic acids such as salicylic acid, naphthoic acid and dicarboxylic acid; polymer compounds having sulfonic acid or carboxylic acid groups in the side chain; boron compounds; urea compounds; Silicon compound; calixarene and the like. Examples of the positive charge control agent include quaternary ammonium salts; polymer type compounds having the quaternary ammonium salt in the side chain; guanidine compounds; imidazole compounds.
[0093]
In the developer according to the present invention, an inorganic fine powder is added together with the toner particles. Thereby, developability, transferability, charging stability, fluidity and durability are improved.
[0094]
As the inorganic fine powder preferably used in the present invention, known ones can be used, and it is particularly preferable that the inorganic fine powder is selected from silica, alumina, titania or a double oxide thereof. Further, silica is more preferable. For example, the silica can be either a so-called dry process produced by vapor phase oxidation of silicon halide or alkoxide, or a so-called wet silica produced from alkoxide, water glass, etc. There are few silanol groups on the surface and inside the silica fine powder, and Na₂O or SO_Three ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0095]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²/ G range gives good results and is used in an amount of 0.3-8 parts by weight, preferably 0.5-5 parts by weight, per 100 parts by weight of toner.
[0096]
By using the inorganic fine powder having a controlled specific surface area as described above, the amount of water adsorbed on the toner particles can be suppressed even when a colorant is present near the toner surface, and the charge amount and charge speed can be controlled. The effect is increased. Further, image defects due to contamination or scraping of the electrostatic latent image carrier or intermediate transfer member by the colorant are prevented in advance. Further, since moderate fluidity is imparted to the toner, the uniform chargeability of the toner is synergistically improved, and the excellent effects as described above are maintained even when a large number of printouts are repeated continuously.
[0097]
Specific surface area is 30m²If it is less than / g, it is difficult to impart adequate fluidity to the toner, and the effect of preventing contamination of the toner carrier caused by the colorant is reduced. Specific surface area is 400m²When the amount exceeds / g, since the inorganic fine powder is embedded in the surface of the toner particles when a large number of sheets are continuously printed out, the fluidity of the toner may be lowered.
[0098]
Further, when the addition amount of the inorganic fine powder is less than 0.3 part by mass, the effect of addition is not manifested. When the addition amount exceeds 8 parts by mass, not only the charging property and fixing property of the toner are caused, but also the free The matching with the image forming apparatus is significantly deteriorated by the inorganic fine powder.
[0099]
In addition, the inorganic fine powder used in the present invention has a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a functional group as necessary for the purpose of hydrophobization and chargeability control. It is possible and preferable to use a silane coupling agent, a treating agent such as an organic silicon compound or an organic titanium compound, or various treating agents in combination.
[0100]
For measurement of the specific surface area, a specific surface area measuring device “Autosorb 1” (manufactured by Yuasa Ionics Co., Ltd.) was used to adsorb nitrogen gas on the sample surface, and the specific surface area was calculated by the BET multipoint method.
[0101]
Furthermore, the inorganic fine powder is preferably treated with at least silicone oil in order to maintain a high charge amount and achieve a high transfer rate and good matching with the image forming apparatus.
[0102]
In the toner according to the present invention, other additives such as a lubricant powder such as a polyethylene fluoride powder, a zinc stearate powder, a polyvinylidene fluoride powder; a cerium oxide powder, Polishing agents such as silicon powder and strontium titanate powder; fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents or conductivity-imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder In addition, a small amount of organic fine particles and inorganic fine particles having opposite polarities can be used as a developability improver.
[0103]
The dry toner of the present invention can be used as it is as a one-component developer or as a two-component developer by mixing with a carrier.
[0104]
When used as a two-component developer, for example, the magnetic carrier to be mixed with the toner is composed of an element selected from iron, copper, zinc, nickel, cobalt, manganese, chromium and the like alone or in a composite ferrite state. The shape of the magnetic carrier used at this time may be spherical, flat, irregular, or the like, and a magnetic carrier whose surface state fine structure (for example, surface irregularity) is appropriately controlled may be used. I can do it. A resin-coated carrier whose surface is coated with a resin can also be suitably used. The average particle diameter of the carrier to be used is preferably 10 to 100 μm, more preferably 20 to 50 μm. Further, when the two-component developer is prepared by mixing these carrier and toner, the toner concentration in the developer is preferably about 2 to 15% by mass.
[0105]
As a method for producing the dry toner of the present invention, a binder resin, a colorant, a wax component and the like are melt-kneaded with a pressure kneader and the like, and then the cooled kneaded product is finely pulverized to a desired toner particle size. A pulverization method in which a pulverized product is classified to adjust a particle size distribution to obtain a toner; suspensions described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842 A method of directly producing toner using a polymerization method; a method of producing a spherical toner by atomizing a melt-kneaded product in air using a disk or a multi-fluid nozzle described in JP-B-56-13945; and soap Known methods such as an emulsion polymerization method typified by a free polymerization method can be used.
[0106]
By the way, since the colorant added to the toner particles generally has many hydrophilic functional groups, the granulated particles of the polymerizable monomer composition are polymerized in an aqueous dispersion medium to form the toner particles. When forming, it may move toward the interface between the polymerizable monomer composition, which is a dispersoid, and the aqueous medium, resulting in reaggregation near the surface of the toner particles. In such a case, not only the charge amount and charging speed of the obtained toner particles but also adversely affect the heat fixing and the like, and hinder matching with the image forming apparatus.
[0107]
On the other hand, the present inventors have previously dispersed / mixed together with a part of the polymerizable monomer composition while appropriately adjusting the colorant as described above within the range of the desired blending amount, and then the suspension polymerization method. It was found that the colorant can be fixed in the toner particles in a good state by producing the toner. For example, in the case of toner particles of a magenta developer, a pigment dispersion composition in which a quinacridone colorant and a monoazo colorant are pre-dispersed / mixed together with a part of the polymerizable monomer composition is manufactured, and this is then used as the remaining polymerizable property. By using the monomer composition together with the suspension polymerization method for toner production, re-aggregation of the quinacridone colorant and monoazo colorant alone is prevented, and the quinacridone colorant in the toner particles It is possible to encapsulate while maintaining the interaction of the monoazo colorant, and it is possible to impart desirable charging characteristics, color developability, and fixing properties to the obtained toner particles. Also, matching with the image forming apparatus is significantly improved. The effects as described above are further improved by making the charge control agent and the polar resin as described above coexist when the pigment dispersion composition is produced.
[0108]
In the method for producing a toner according to the present invention, known inorganic and organic dispersants can be used as a dispersant used when preparing an aqueous dispersion medium. Specifically, as the inorganic dispersant, for example, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Examples include calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of organic dispersants include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch, and the like.
[0109]
Commercially available nonionic, anionic and cationic surfactants can also be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like can be used.
[0110]
In the method for producing a toner according to the present invention, an inorganic poorly water-soluble dispersant is preferable, and a poorly water-soluble inorganic dispersant that is soluble in an acid may be used. Moreover, in this invention, when preparing a water-based dispersion medium using a slightly water-soluble inorganic dispersing agent, these dispersing agents are 0.2-2. It is preferable to use it in such a ratio that it becomes 0 parts by mass. Moreover, in this invention, it is preferable to prepare an aqueous dispersion medium using 300-3,000 mass parts water with respect to 100 mass parts of polymerizable monomer compositions.
[0111]
In the present invention, when preparing an aqueous dispersion medium in which the above-mentioned poorly water-soluble inorganic dispersant is dispersed, a commercially available dispersant may be used as it is, but a dispersion having a fine uniform particle size may be used. In order to obtain agent particles, a slightly water-soluble inorganic dispersant as described above may be prepared in a liquid medium such as water under high-speed stirring. For example, when tricalcium phosphate is used as a dispersant, a preferred dispersant can be obtained by mixing aqueous sodium phosphate solution and aqueous calcium chloride solution under high speed stirring to form fine particles of tricalcium phosphate. .
[0112]
Next, the polymerizable monomer composition used in the toner production method of the present invention will be described. The polymerizable monomer composition comprises at least a polymerizable vinyl monomer, a quinacridone colorant, and a monoazo colorant, preferably, in addition to this, a charge control agent, a wax component, and further if necessary. It is prepared by dissolving and mixing various additives.
[0113]
As the polymerizable vinyl monomer used in this case, the polymerizable monomers as mentioned above are appropriately mixed and used so that the theoretical glass transition temperature (Tg) is 40 to 75 ° C. In particular, when Tg is high, when a color toner for forming a full-color image is produced, the color mixing property at the time of fixing each color toner is lowered, the color reproducibility is poor, and the transparency of the OHP image is further lowered. Therefore, it is not preferable.
[0114]
Specific examples of the polymerization initiator used in the toner manufacturing method according to the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyro. Azo or diazo polymerization such as nitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile Initiators; peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used. Although the usage-amount of these polymerization initiators changes with the target degree of polymerization, generally 5-20 mass parts is used with respect to 100 mass parts of polymerizable vinylic monomers. The kind of the polymerization initiator varies slightly depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.
[0115]
In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like may be further added to the polymerizable monomer composition. These additives can be added in advance to the polymerizable monomer composition, and can be appropriately added during the polymerization reaction, if necessary.
[0116]
The image forming method of the present invention is an image forming method for forming a full color image by sequentially repeating a plurality of image forming steps.
After image formation with the chromatic developer already described above is started after the first image formation step, full-color image formation is achieved by forming an image with the black developer in the final image formation step,
Each image forming step includes at least (a) a charging step for charging an image carrier for carrying an electrostatic latent image; (b) an exposure step for forming an electrostatic latent image on the charged image carrier by image exposure. (C) a developing step in which the electrostatic latent image is developed with toner carried on the surface of the toner carrier to form a toner image; (d) the toner image formed on the surface of the image carrier is intermediate A transfer step of transferring to a transfer material with or without a transfer member; and (e) a cleaning step of cleaning and removing toner remaining on the surface of the image carrier after the transfer step. Using the image carrier, the above steps (a) to (e) are repeated,
In addition, the image forming apparatus includes a fixing step of forming a fixed image by heating and fixing the toner image transferred onto the transfer material.
[0117]
Next, the image forming method of the present invention will be described with reference to the accompanying drawings.
[0118]
FIG. 1 shows an example in which the image forming method of the present invention is applied to a full-color image forming apparatus. Toner images of different colors are formed in a plurality of image forming units, and these are sequentially superimposed on the same transfer material. 1 is a schematic explanatory view showing a full-color image forming apparatus using an image forming method for forming a multicolor image by transferring.
[0119]
The full-color image forming apparatus main body is provided with a first image forming unit Pa, a second image forming unit Pb, a third image forming apparatus unit Pc, and a fourth image forming apparatus unit Pd. After the toner images of different colors are developed by the image forming apparatus unit, the toner images are transferred onto a transfer material conveyed by a transfer material conveyance belt, and further heated and pressed to obtain a full color image.
[0120]
The configuration of each image forming unit provided in the image forming apparatus will be described by taking the first image forming unit Pa as an example.
[0121]
The first image forming unit Pa includes a photosensitive drum 19a having a diameter of 24 mm as an electrostatic latent image carrier, and the photosensitive drum 19a rotates and moves in the direction of arrow a.
[0122]
As charging means, a primary charging roller 16a having a diameter of 12 mmφ is disposed so as to be in contact with the surface of the photosensitive drum 19a. An electrostatic latent image is formed on the photosensitive drum 19a uniformly primary-charged by the primary charging roller 16a by the laser light 14a irradiated in accordance with the image signal from the exposure device 13a.
[0123]
The developing device 17a has developing means for developing the electrostatic latent image formed on the surface of the photosensitive drum 19a to form a toner image. The first color toner and a thin layer of the toner are provided. A developing roller 15a having a diameter of 18 mm and carrying the toner is disposed so as to be in contact with the photosensitive drum 19a through a thin layer of toner, and the first color toner image is developed.
[0124]
The toner image of the first color developed on the photosensitive drum 19a is transferred to the surface of a transfer material (recording material) S conveyed by a belt-like transfer material carrier 20 by a transfer blade 11a as transfer means. The The transfer blade 11a is in contact with the back surface of the transfer material carrier 20, and can apply a transfer bias by the bias applying means 12a.
[0125]
After the transfer, the surface of the photosensitive drum 19a is used for subsequent electrostatic latent image formation after the transfer residual toner is removed by the cleaning device 18a.
[0126]
The image forming apparatus according to the present invention has the same configuration as that of the first image forming unit Pa, and the second image forming apparatus unit Pb and the third image forming apparatus unit Pc having different toner colors held in the developing device. , And the fourth image forming apparatus unit Pd. For example, the first image forming apparatus unit Pa is yellow toner, the second image forming apparatus unit Pb is magenta toner, the third image forming apparatus unit Pc is cyan toner, and the fourth image forming apparatus unit Pd. In this case, black toner is used, and each color toner image is sequentially transferred onto a transfer material in a transfer portion of each image forming apparatus unit. At this time, the transfer material is moved while aligning the registration during this process, and the toners of the respective colors are superimposed on the same transfer material. When the transfer is completed, the transfer material S is separated from the transfer material carrier 20 by the separation charger 21. It is sent to the fixing device 23 by a conveying means such as a conveying belt, and a desired full-color image is obtained by only one fixing.
[0127]
In FIG. 1, a transfer material carrier 20 is an endless belt-like member, and this belt member moves in the direction of arrow e by a driving roller 80 as image formation proceeds. Around the transfer material carrier 20, a belt driven roller 81, a belt static eliminating device 82, and a belt cleaning device 83 are disposed, and a pair of registration rollers 24 supports the transfer material S in the transfer material holder. It is provided for transporting to the body.
[0128]
In the image forming apparatus as described above, as a transfer unit, a roller-like transfer roller or a non-contact charging unit such as a corona charger is used instead of the transfer blade that contacts the back side of the transfer material carrier. It is also possible.
[0129]
In addition, as a transport means for transporting the transfer material, a transport belt using a Tetron fiber mesh, a polyethylene terephthalate resin, a polyimide resin, and a urethane resin are thin from the viewpoint of ease of processing and durability. A conveyance belt using a dielectric sheet is used, but a configuration having a drum-type conveyance unit may be used.
[0130]
In the image forming apparatus as described above, each color toner image is sequentially transferred onto the same transfer material in the transfer section of each image forming apparatus unit, so that the toner image to which the previously transferred toner image is transferred later is carried. In contact with the photosensitive drum. At this time, if there is an unstable charged toner particle that forms a toner image on the transfer material that has already been transferred, the so-called photosensitive drum that is subsequently transferred is called back. A “re-transfer phenomenon” occurs, which leads to a decrease in image quality. However, in the present invention, by specifying the type and content of the colorant in each toner particle of the chromatic developer, it is possible to prevent the image defects as described above.
[0131]
The color image forming developer kit of the present invention includes a primary transfer step of transferring a toner image formed by developing an electrostatic latent image formed on an electrostatic latent image carrier to an intermediate transfer member, and an intermediate It is possible to satisfactorily adapt to an image forming apparatus having a secondary transfer process for transferring a toner image transferred to a transfer body onto a transfer material.
[0132]
The heating and pressing means used in the image forming method of the present invention forms a fixed image by heating and fixing a toner image on a transfer material. The heating and pressing means includes (i) at least heating. (Ii) a liquid for preventing offset applied to a contact surface with a toner image on a transfer material, having a rotary heating member having a body and a rotary pressure member that forms a nip portion by mutual pressure contact with the rotary heating member Consumption of 0-0.025mg / cm²(Iii) The transfer material is heated and pressed by the rotary heating member and the rotary pressure member while holding and transferring the transfer material at the nip portion. It is.
[0133]
The rotary heating member constituting a part of the heat fixing means is for applying heat for fixing the toner image on the transfer material, and is used for (i) a heat roller type heat pressure means. A cylindrical member having a heating body for applying heat to the toner image, and (ii) used for a film-type heating and pressing means, and fixed to a support for applying heat to the toner image inside. A cylindrical heat-resistant endless film-like member having a supported heating body and driven to move while being in pressure contact with the heating body; (iii) used for electromagnetic induction heating and pressurizing means; A cylindrical heat-resistant endless film member having a heat generating layer for applying heat to the toner image by electromagnetic induction heat generation by the action of the magnetic field generating means.
[0134]
The rotary pressure member forms a nip portion by mutual pressure contact with the rotary heating member, and heats and presses the toner image on the transfer material while nipping and transferring the transfer material at the nip portion.
[0135]
In the image forming method of the present invention, the consumption of the offset preventing liquid applied to the contact surface with the toner image on the transfer material is 0 to 0.025 mg / cm.²More preferably, the offset preventing liquid is not applied at all (based on the unit area of the transfer material). As a result, the problems caused by the offset preventing liquid as described above can be solved in advance, and the performance of the heating and pressing means can be maintained over a long period of time by using the developer as described above, and an excellent fixed image can be obtained. Can be obtained.
[0136]
For measuring the consumption of the liquid for preventing offset, the recycled paper for general office use (recycled pulp blending ratio ≧ 70%) corresponding to the maximum paper passing area of the target heating and pressurizing means is used. Total area (cm) of recycled paper using the weight (mg) of anti-offset liquid consumed when passing through the sheet²) Divided by (mg / cm²) Is defined.
[0137]
The toner particles exhibiting the shape distribution as described above generally tend to have a small specific surface area and volume. For example, when a pigment composition that exhibits acicular crystals such as a quinacridone colorant is added, the tip of the acicular crystals If the toner particles are unevenly distributed in the vicinity of the surface of the toner particles, or if they are severe, the reagglomerates are arranged along the particle surface, adversely affecting the surface resistance and charging characteristics of the toner particles, and developing. In addition to lowering the characteristics, transfer characteristics, and matching with the image forming apparatus, the heating and pressure fixing unit is particularly heated with a small amount of offset preventing liquid applied to the contact surface with the toner image on the transfer material. There is an effect when using the pressure fixing means, and the fixing device is used for fixing a color image in which a large number of printouts are repeated continuously or a plurality of toner layers are formed on a transfer material. When that causes a temperature drop in the stimulation occurs over "image peeling" and several places poor fixing a diameter of about 2mm called the fixed image surface. At this time, since a minute piece of the fixed image that has been peeled off is also offset in the heat and pressure fixing means, a serious problem occurs in the heat and pressure fixing means. In particular, it becomes apparent when using the heating and pressing means as described above.
[0138]
However, the toner particles according to the present invention can improve the dispersion state in the toner particles by specifying the type and content of the colorant and suppress the reaggregation of the colorant. Can be prevented in advance.
[0139]
【Example】
Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited thereto.
[0140]
(Toner Production Example 1)
In a 4-liter flask for 2 liters equipped with a high-speed stirring device CLEARMIX (M-Technics), 700 g of ion-exchanged water and 0.1 mol / L-Na_ThreePO_Four800 g of the aqueous solution was added, the number of revolutions of the high-speed stirring device was set to 15000 rpm, and the mixture was heated to 60 ° C. Here 1.0 mol / L-CaCl₂70 parts by weight of an aqueous solution is added, and a minute water-insoluble dispersant Ca_Three(PO_Four)₂An aqueous dispersion medium containing was prepared. Further, it was re-prepared with diluted hydrochloric acid so that the pH of the aqueous dispersion medium became 5.5.
[0141]
On the other hand, as dispersoid,
・ 77 parts by mass of styrene monomer
・ 23 parts by mass of 2-ethylhexyl acrylate monomer
・ 0.2 parts by weight of divinylbenzene monomer
・ Condensed azo pigment 3 parts by mass
(C.I. Pigment Yellow 93)
・ 3 parts by weight of yellow dye
(C.I. Solvent Yellow 162)
・ Polyester resin 5 parts by mass
(Peak molecular weight = 4500, acid value = 25 mgKOH / g)
・ Di-tert-butylsalicylic acid 1 part by mass
-Ester wax (melting point = 65 ° C) 15 parts by mass
After dispersing the mixture consisting of 3 for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.), 3 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) is added, and the polymerizable monomer composition is added. Was prepared.
[0142]
Next, the polymerizable monomer composition is put into the aqueous dispersion medium, and N.sub.₂Under an atmosphere, the polymerizable monomer composition was granulated by stirring for 10 minutes while maintaining the rotation speed of the high-speed stirring device at 15000 rpm. Thereafter, the stirring device was replaced with a paddle stirring blade, and maintained at the same temperature while stirring at 200 rpm. When the polymerization conversion rate of the polymerizable vinyl monomer reached 95%, 0.1 mol / L An aqueous NaOH solution was added to change the pH of the aqueous dispersion medium to 10. Further, the reaction temperature was raised to 85 ° C., and the polymerization reaction was completed when the polymerization conversion rate was almost 100%.
[0143]
After completion of the polymerization, the residual monomer was distilled off under reduced pressure by heating, and after cooling, diluted hydrochloric acid was added to dissolve the hardly water-soluble dispersant. Further, after washing with water several times, a drying treatment was performed using a conical ribbon dryer (manufactured by Okawara Seisakusho) to obtain polymer particles (Y-1).
[0144]
100 parts by mass of the polymer particles (Y-1) and oil-treated silica fine powder (BET specific surface area = 200 m²/ G) 1.2 parts by mass and hydrophobized titanium oxide fine powder (BET specific surface area = 50 m²/ G) 0.3 parts by mass was dry-mixed with a Henschel mixer (manufactured by Mitsui Kinzoku Co., Ltd.) to obtain toner (Y-1).
[0145]
The toner (Y-1) had a circle-equivalent number average diameter of 5.2 μm, an average circularity in the circularity frequency distribution of 0.983, and a circularity standard deviation of 0.019. Further, the GPC peak molecular weight of the soluble component of THF of the binder resin component constituting the toner particles was 18,000, and the THF insoluble content was 20% by mass.
[0146]
(Toner Production Examples 2 and 3)
Change the addition amount of condensed azo pigment and yellow dye and divinylbenzene monomer used as colorants, set temperature during polymerization reaction during toner production, pH of aqueous dispersion medium, and polymerization at pH switching The polymer particles (Y-2) and (Y-3) were obtained in the same manner as in the toner production example 1 except that the conversion rate was changed, and then the toners (Y-2) and (Y-3) were added. Prepared.
[0147]
(Toner Production Example 4)
The following mixture was dispersed for 4 hours using an attritor (Mitsui Metals Co., Ltd.) to prepare a pigment dispersion composition.

[0148]
In a separate container,
・ 40 parts by mass of styrene monomer
-17 parts by mass of n-butyl acrylate monomer
・ 0.2 parts by weight of divinylbenzene monomer
Ester wax (melting point = 60 ° C) 7 parts by mass
57 parts by mass of the pigment dispersion composition was added to the mixture consisting of the components, dispersed and dissolved while heating to 60 ° C., and then 3 parts by mass of 2,2-azobis (2,4-dimethylvaleronitrile) was added. A polymerizable monomer composition as a dispersoid was prepared.
[0149]
The polymer particles (M-1) were prepared in the same manner as in Toner Production Example 1 except that the setting temperature during the polymerization reaction during the toner production, the pH of the aqueous dispersion medium, and the polymerization conversion rate during the pH switching were changed. After the toner was obtained, toner (M-1) was prepared.
[0150]
(Toner Production Examples 5 to 7)
Change the addition amount of quinacridone pigment and monoazo pigment and divinylbenzene monomer used as colorants, set temperature during polymerization reaction during toner production, pH of aqueous dispersion medium, and polymerization at pH switching Polymer particles (M-2) to (M-4) were obtained in the same manner as in Toner Production Example 1 except that the conversion rate was changed, and then toners (M-2) to (M-4) were obtained. Prepared.
[0151]
(Toner Production Examples 8 to 10)
As a phthalocyanine colorant, C.I. I. Pigment Blue 15: 3 was used, and the same procedure as in toner production example 1 was performed except that the set temperature during the polymerization reaction during the toner production, the pH of the aqueous dispersion medium, and the polymerization conversion rate during the pH switching were changed. After obtaining the polymer particles (C-1) to (C-3), toners (C-1) to (C-3) were prepared.
[0152]
(Toner Production Example 11)
6 parts by weight of carbon black (average particle size = 35 nm) is used as a colorant and 2 parts by weight of a monoazo Fe complex is used as a charge control agent. The set temperature at the time of the polymerization reaction during toner production, the pH of the aqueous dispersion medium, and the pH A polymer particle (Bk-1) was obtained in the same manner as in Toner Production Example 1 except that the polymerization conversion rate at the time of switching was changed, and then a toner (Bk-1) was prepared.
[0153]
(Comparative toner production examples 1 to 3)
Except for changing the type and amount of the colorant, and changing the set temperature during the polymerization reaction during the toner production, the pH of the aqueous dispersion medium, and the polymerization conversion rate during the pH switching, Similarly, after obtaining polymer particles (y-1), (m-1), and (m-2), toners (y-1), (m-1), and (m-2) were prepared.
[0154]
(Toner Production Examples 12 to 15)
The polymer particles (Y-1), (M-1), (C-1), and (Bk-1) are each 100 parts by mass, hydrophobized titanium oxide fine powder (BET specific surface area = 270 m).²/ G) 1.0 part by mass and oil-treated silica fine powder (BET specific surface area = 50 m²/ G) Toners (Y-1b), (M-1b), (C-1b), and (Bk-1b) obtained by dry mixing 0.5 parts by mass with a Henschel mixer (manufactured by Mitsui Kinzoku Co., Ltd.) 92 parts by mass of a resin-coated carrier is uniformly dry-mixed with 8 parts by mass of these toners using a Nauta mixer (manufactured by Hosokawa Micron), and two-component developers (Y-1b), (M-1b), (C- 1b) and (Bk-1b).
[0155]
(Comparative toner production examples 4 to 5)
Two-component developers (y-1b) and (m-1b) were prepared in the same manner as in Toner Production Example 12 except that the polymer particles (y-1) and (m-1) were used.
[0156]
Tables 1 and 2 summarize the colorant formulations used in the above toner production examples and comparative toner production examples, and various properties of the obtained toner.
[0157]
[Table 1]

[0158]
[Table 2]

[0159]
<Example 1>
An image forming method is used in which toner images of different colors are formed by a plurality of image forming units shown in FIG. 1, and these are sequentially superimposed and transferred onto the same transfer material to form a multicolor image. Using a full-color image forming apparatus, the first image forming apparatus unit Pa, the second image forming unit Pb, the third image forming apparatus unit Pc, and the fourth image forming apparatus unit Pd are obtained in the above toner manufacturing example. The toners (Y-1), (M-1), (C-1), and (Bk-1) are filled, and each color toner is printed in a normal temperature and humidity environment while being replenished as necessary. Using a test pattern created so that the ratio is 4 area%, using “Recycled Paper EN-100” (recycled pulp blending rate = 100%) as a transfer material, printing 16 sheets / min (A4 size paper) Out speed In went the print-out test of 10,000 sheets.
[0160]
The fixing device used was a heat roller type heating and pressing means in which a separation claw and an offset preventing liquid application mechanism were not provided. For the heating roller, an aluminum cylindrical metal core is primed, and then a dimethyl silicone rubber elastic layer and a surface layer made of a 50 μm thick PFA tube are used through the primer layer. As the pressure roller, a SUS cored bar was subjected to primer treatment, an elastic layer of dimethyl silicone rubber was provided, and a surface layer was further provided by a PFA tube having a thickness of 50 μm via the primer layer. In addition, a halogen heater is provided as a heating element inside the cylindrical core of the heating roller so that the surface temperature of the fixing roller is 180 ° C. when the heating / pressurizing unit is operated, and the heating roller and the heating core are heated. A contact pressure of 245 N (25 kgf) was applied to the pressure roller so that a nip portion with a width of 3 mm was formed.
[0161]
The obtained printout image was excellent in color reproducibility, fine line reproducibility, and image light fastness, and the printout test was completed while maintaining the initial color reproducibility.
[0162]
In addition, there was no image peeling in the printout image, and after the printout test was completed, the roller surface of the fixing device was visually evaluated. There was no problem of toner adhesion and the matching with the image forming device. Was also found to be excellent.
[0163]
These evaluation results are summarized in Table 3.
[0164]
<Examples 2 to 5>
Each image forming apparatus unit was filled with the chromatic color toner obtained in the above toner production example in order, and a printout test was conducted in the same manner as in Example 1 while replenishing sequentially as necessary. Got.
[0165]
These evaluation results are summarized in Table 3.
[0166]
<Comparative example 1>
Each image forming apparatus unit was sequentially filled with the comparative chromatic color toner obtained in the above-mentioned comparative toner production example, and a printout test was performed in the same manner as in Example 1 while replenishing sequentially as necessary. However, color reproducibility, fine line reproducibility, and image light resistance were not sufficient.
[0167]
In addition, problems such as image peeling occurred in the printout image, and a phenomenon such as the printout image being wound around the roller surface of the fixing device during the printout test was observed.
[0168]
These evaluation results are summarized in Table 3.
[0169]
<Comparative Examples 2 and 3>
Each image forming apparatus unit was sequentially filled with the comparative toners obtained in the comparative toner production examples, and a printout test was conducted in the same manner as in Example 1 while replenishing sequentially as necessary. The reproducibility, fine line reproducibility, image light resistance, image peeling, and matching with the fixing device were not sufficient levels.
[0170]
These evaluation results are summarized in Table 3.
[0171]
<Example 6>
Each of the first image forming apparatus unit Pa, the second image forming unit Pb, the third image forming apparatus unit Pc, and the fourth image forming apparatus unit Pd is modified for two-component contact development. The two-component developers (Y-1b), (M-1b), (C-1b), and (Bk-1b) obtained in the production examples are filled, and toners (Y-1b), (M -1b), (C-1b) and (Bk-1b) were sequentially supplied, and a printout test was conducted in the same manner as in Example 1.
[0172]
The obtained printout image was excellent in color reproducibility, fine line reproducibility, and image light fastness, and the printout test was completed while maintaining the initial color reproducibility.
[0173]
In addition, there was no image peeling in the printout image, and after the printout test was completed, the roller surface of the fixing device was visually evaluated. There was no problem of toner adhesion and the matching with the image forming device. Was also found to be excellent.
[0174]
These evaluation results are summarized in Table 3.
[0175]
<Comparative example 4>
Each of the first image forming apparatus unit Pa, the second image forming unit Pb, the third image forming apparatus unit Pc, and the fourth image forming apparatus unit Pd is modified for two-component contact development. The two-component developers (y-1b), (m-1b), (C-1b), and (Bk-1b) obtained in the production examples and the comparative toner production examples are filled, and if necessary, the toner A printout test was conducted in the same manner as in Example 6 while sequentially supplying (y-1b), (m-1b), (C-1b), and (Bk-1b). Reproducibility, image light resistance, image peeling, matching with a fixing device, and the like were not sufficient levels.
[0176]
These evaluation results are summarized in Table 3.
[0177]
[Table 3]

[0178]
The description of the evaluation items described in the examples and comparative examples and the evaluation criteria will be described.
[0179]
[Printout test]
<1> Color space volume on plain paper
Ordinary paper for ordinary copying machines (75 g / m²) By measuring the full-color image obtained above with "Spectrophotometer SP68" (manufactured by X-Rite), L standardized by the International Commission on Illumination (CIE)^*a^*b^*Lightness L of the color system^*A representing the degree of red to green^*, And b representing the degree of yellow to blue^*The color space solid determined by the above is determined, and the volume of the color space solid is obtained. The larger the volume (numerical value) of the color space solid, the better the color reproducibility.
A: Over 2.5 million
B: 2 million or more, less than 2.5 million
C: 1.5 million or more, less than 2 million
D: Less than 1.5 million
[0180]
<2> Fine line reproducibility
This is an evaluation related to the image quality and gradation of a graphical image, and the reproducibility of fine lines in a printout image as shown in FIG. 2 was evaluated.
A: Shows good fine line reproducibility
B: Minor fluctuations in the width of fine lines are observed
C: Thin lines and scattering are conspicuous
D: Fine lines are broken in some places, and reproducibility is poor
[0181]
<3> Color reproducibility of projected images
The full-color image obtained on the transparency film is converted into a transmission image by an overhead projector “OHP 9550” (manufactured by 3M), and the secondary color portion (red: red: Yellow: 50% / Magenta 50%, Green: Cyan 50% / Yellow 50%, Blue: Magenta 50% / Cyan 50%) were visually evaluated and measured with a spectral radiance meter (Photo Research). L^*a^*b^*The color space solid indicated by the color system was determined, and the volume of the color space solid was determined.
[0182]
Visual evaluation of secondary color
A: The color reproducibility of secondary colors (red and blue) is also vivid and excellent in transparency.
B: Excellent primary color color reproducibility and transparency, but slightly inferior secondary color reproducibility
C: Slightly inferior to primary color reproducibility and transparency
D: Inferior color reproducibility of primary color, resulting in blurring
[0183]
Color space volume
A: Over 2.5 million
B: 2 million or more, less than 2.5 million
C: 1.5 million or more, less than 2 million
D: Less than 1.5 million
[0184]
<4> Image peeling
Slightly thick transfer paper (105 g / m², A4 size) and the toner amount is 0.8 mg / cm²A solid image was prepared so as to have a degree, and the occurrence of image peeling on the surface of the obtained image was visually evaluated. As the number of image peeling portions is smaller, the occurrence is suppressed.
A: Not generated
B: 1 to 5 locations
C: 6 or more and 10 or less
D: 11 locations or more (or image peeling with a diameter of 2 mm or more occurs)
[0185]
<5> Image light resistance
The amount of toner on the transfer paper is 0.6 mg / cm²A solid image of the same degree was prepared and evaluated according to “JIS K 7102” using an ultraviolet auto fade meter “FAL-AU” (manufactured by Suga Test Instruments Co., Ltd.) using a carbon arc lamp as a light source. The maximum irradiation time was 240 hours, the image density maintenance ratio before and after the light irradiation was calculated, and the light resistance of the image was evaluated. The closer the image density maintenance rate (%) is to 100%, the better the image light resistance.
A: 90% or more
B: 80% or more and less than 90%
C: 65% or more and less than 80%
D: Less than 65%
[0186]
[Matching evaluation with fixing unit]
After completion of the printout test, the appearance of the residual toner on the heating roller and the influence on the printout image were visually evaluated.
A: No toner sticking
B: Contamination due to paper dust and toner sticking to the edge were observed, but the effect on the fixed image was slight.
C: Although slight toner contamination occurs on the back surface of the printout image due to contamination by paper dust or toner adhering to the edge, there is almost no effect on the fixed image.
D: Effect of fixing toner on fixed image and wrapping of printout image during printout test
[0187]
【The invention's effect】
As described above, according to the present invention, toner images of different colors are formed in a plurality of image forming units, and these are sequentially superimposed and transferred onto the same transfer material to form a multicolor image. By using a color image forming developer kit consisting of a chromatic developer with a specified colorant and a black developer in an image forming apparatus using the image forming method, a high-definition and high-quality image that achieves a wide range of color reproduction is achieved. When a full-color image with a resolution is formed, sufficient image light resistance is achieved, and even when it is applied to a fixing device that does not use an anti-offset liquid, toner remains on the surface of a fixing member such as a fixing roller of the fixing device. Since it is possible to prevent adhesion and residue, good color reproduction can be stably obtained even when many sheets are printed out.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a full-color image forming apparatus used in an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a line image for evaluating reproducibility of a thin line.
[Explanation of symbols]
15a Development roller
17a, 17b, 17c, 17d Developing device
19a, 19b, 19c, 19d Photosensitive drum
20 Transfer material carrier
23 Fixing device

Claims (12)

A developer kit for color image formation comprising at least three chromatic developers, a yellow developer, a magenta developer, and a cyan developer,
Each of the above chromatic developers has toner particles and inorganic fine powder containing at least a binder resin, a colorant and a wax component,
And as a colorant in the toner particles,
a. The yellow toner particles in the yellow developer include a condensed azo pigment represented by the following structural formula (1) and C.I. I. Solvent Yellow 9, 17, 24, 31, 35, 58, 93, 100, 102, 103, 105, 112, 162, 163, C.I. I. Disperses Yellow 42, 64, 82, 160, 201, 224, any one selected from the group of yellow dyes (each according to the name described in Color Index 4th edition), and the total content is 1 -20% by mass, and the mass ratio of the content is condensed azo pigment: monoazo dye = 25: 75 to 75:25,

b. The magenta toner particles in the magenta developer contain a quinacridone pigment represented by the following structural formula (2) and a monoazo pigment represented by the following structural formula (3), and the total content thereof is 1 to 20% by mass. The mass ratio of the content is quinacridone pigment: monoazo pigment = 25: 75 to 75:25,

[X ₁ and X ₂ represent a hydrogen atom or a substituent selected from an alkyl group, an alkoxy group, and a halogen group. ]

c. A developer kit for forming a color image, wherein the cyan toner particles in the cyan developer contain a phthalocyanine pigment and the content thereof is 1 to 10% by mass. 2. The developer kit for color image formation according to claim 1, comprising at least three chromatic color developers of a yellow developer, a magenta developer and a cyan developer, and a black developer. The toner particles in the developer have a circle-equivalent number average diameter D1 (μm) of 2 to 10 μm and an average circularity of 0 in a number-based circle-equivalent diameter-circularity scattergram measured by a flow particle image measuring device. 950 to 0.995, the circularity standard deviation is less than 0.040, the main component of the binder resin is a styrene-acrylic resin, and the soluble content of tetrahydrofuran (THF) in the binder resin 3. The developer kit for color image formation according to claim 1, having a peak molecular weight of 5,000 to 30,000 and a THF-insoluble content of 5 to 35% by mass in gel permeation chromatography (GPC). . A condensed azo pigment used for toner particles in a yellow developer is C.I. I. Pigment Yellow 93, 94, 95, 128, and 166, and the yellow dye is C.I. I. Solvent Yellow 93, 105, 112, 162, 163, C.I. I. The color image according to any one of claims 1 to 3, wherein the color image is any one selected from the group of Disperse Yellow 42, 64, 160, and 201 (each according to a name described in the color index fourth edition). Developer kit for formation. The quinacridone pigment used for the toner particles in the magenta developer is C.I. I. Pigment Red 122, 202, C.I. I. Pigment Violet 19 and / or a solid solution pigment thereof, and the monoazo pigment is C.I. I. Pigment Red 5, 31, 146, 147, 150, 176, 184, 185, or 269 (each according to the name described in Color Index 4th Edition) The developer kit for forming a color image according to any one of claims 1 to 3. The phthalocyanine pigment used for the toner particles in the cyan developer is C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, or 16 (each according to the name described in Color Index 4th Edition) A developer kit for forming a color image according to any one of claims 1 to 3. In an image forming method for forming a full-color image by sequentially repeating a plurality of image forming steps,
After image formation with a chromatic color developer is started after the first image formation step, full color image formation is achieved by forming an image with black developer in the final image formation step.
Each image forming step includes at least (a) a charging step for charging an image carrier for carrying an electrostatic latent image; (b) an exposure step for forming an electrostatic latent image on the charged image carrier by image exposure. (C) a developing step in which the electrostatic latent image is developed with toner carried on the surface of the toner carrier to form a toner image; (d) the toner image formed on the surface of the image carrier is intermediate A transfer step of transferring to a transfer material with or without a transfer member; and (e) a cleaning step of cleaning and removing toner remaining on the surface of the image carrier after the transfer step. Using the image carrier, the above steps (a) to (e) are repeated,
And a fixing step of forming a fixed image by heating and fixing the toner image transferred onto the transfer material,
The chromatic developer is a yellow developer, a magenta developer, and a cyan developer having toner particles and inorganic fine powder containing at least a binder resin, a colorant, and a wax component,
And as a colorant in the toner particles,
a. The yellow toner particles in the yellow developer include a condensed azo pigment represented by the following structural formula (1) and C.I. I. Solvent Yellow 9, 17, 24, 31, 35, 58, 93, 100, 102, 103, 105, 112, 162, 163, C.I. I. Disperses Yellow 42, 64, 82, 160, 201, 224, any one selected from the group of yellow dyes (each according to the name described in Color Index 4th edition), and the total content is 1 -20% by mass, and the mass ratio of the content is condensed azo pigment: monoazo dye = 25: 75 to 75:25,

b. The magenta toner particles in the magenta developer contain a quinacridone pigment represented by the following structural formula (2) and a monoazo pigment represented by the following structural formula (3), and the total content thereof is 1 to 20% by mass. The mass ratio of the content is quinacridone pigment: monoazo pigment = 25: 75 to 75:25,

[X ₁ and X ₂ represent a hydrogen atom or a substituent selected from an alkyl group, an alkoxy group, and a halogen group. ]

c. A cyan toner particle in a cyan developer contains a phthalocyanine pigment, and the content thereof is 1 to 10% by mass. The toner particles in the developer have a circle-equivalent number average diameter D1 (μm) of 2 to 10 μm and an average circularity of 0 in a number-based circle-equivalent diameter-circularity scattergram measured by a flow particle image measuring device. 950 to 0.995, the circularity standard deviation is less than 0.040, the main component of the binder resin is a styrene-acrylic resin, and the soluble content of tetrahydrofuran (THF) in the binder resin The image forming method according to claim 7, having a peak molecular weight of 5,000 to 30,000 and a THF-insoluble content of 5 to 35% by mass in gel permeation chromatography (GPC). A condensed azo pigment used for toner particles in a yellow developer is C.I. I. Pigment Yellow 93, 94, 95, 128, and 166, and the yellow dye is C.I. I. Solvent Yellow 93, 105, 112, 162, 163, C.I. I. 9. The image forming method according to claim 7, wherein the image forming method is any one selected from the group of Disperse Yellow 42, 64, 160, and 201 (each according to a name described in the color index fourth edition). The quinacridone pigment used for the toner particles in the magenta developer is C.I. I. Pigment Red 122, 202, C.I. I. Pigment Violet 19 and / or a solid solution pigment thereof, and the monoazo pigment is C.I. I. Pigment Red 5, 31, 146, 147, 150, 176, 184, 185, or 269 (each according to the name described in Color Index 4th Edition) The image forming method according to claim 7 or 8, wherein: The phthalocyanine pigment used for the toner particles in the cyan developer is C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, and 16 (each according to the name described in the color index 4th edition). The image forming method according to claim 7, wherein the image forming method is an image forming method. The heating and pressing means includes (i) a rotating heating member having at least a heating body, and a rotating and pressing member that forms a nip portion by mutual pressure contact with the rotating heating member, and (ii) a toner image on the transfer material; The consumption of the liquid for preventing offset applied to the contact surface is set to 0 to 0.025 mg / cm ² (based on the unit area of the transfer material). (Iii) The transfer material is nipped and conveyed at the nip portion. The image forming method according to claim 7, wherein the toner image on the transfer material is fixed while being heated and pressed by the rotary heating member and the rotary pressure member.

Images