JP2004061730A - Electrophotographic developing developer, electrophotographic developing method using the electrophotographic developing developer, and method for manufacturing electrophotographic developing carrier used for the electrophotographic developing developer - Google Patents

Abstract

A developer which has good dot reproducibility, good granularity in highlight portions, little edge effect, high image density, high image quality with little background smear, and hardly causes carrier adhesion. I will provide a. Another object of the present invention is to provide a developer container containing a developer and an image forming apparatus equipped with the container. Further, a method for manufacturing a carrier is provided.
The developer for electrophotographic development is obtained by mixing toner particles having a weight average particle diameter Dt of at most 8 μm containing at least a binder resin and a colorant with a carrier, and forming a carrier core material constituting the carrier. The weight average particle diameter is 20 to 45 μm, the content of particles having a particle diameter of 44 μm or less in the carrier core material is 80% by weight or more, and the content of particles having a particle diameter of 22 μm or less is 5.0% by weight or less. In addition, the magnetic moment at 1 KOe of the carrier core material is 40 emu / g or more, and the high resistance coating layer is formed on the surface of the carrier core material and the low resistance coating layer B is formed thereon.
[Selection diagram] None

Description

【００４３】
上記（１）式中、Ｒ^１は水素原子、ハロゲン原子、ヒドロキシ基、メトキシ基、炭素数１〜４の低級アルキル基、またはアリール基（フェニル基、トリル基など）を示し、Ｒ^２は炭素数１〜４のアルキレン基、またはアリーレン基（フェニレン基など）を示す。
【００４４】
上記（２）式のアリール基において、その炭素数は６〜２０、好ましくは６〜１４である。このアリール基には、ベンゼン由来のアリール基（フェニル基）の他、ナフタレンやフェナンスレン、アントラセン等の縮合多環式芳香族炭化水素由来のアリール基及びビフェニルやターフェニル等の鎖状多環式芳香族炭化水素由来のアリール基等が包含される。
該アリール基には、各種の置換基が結合していてもよい。
【００４５】
上記（２）式のアリーレン基において、その炭素数は６〜２０、好ましくは６〜１４である。このアリーレン基には、ベンゼン由来のアリーレン基（フェニレン基）の他、ナフタレンやフェナンスレン、アントラセン等の縮合多環式芳香族炭化水素由来のアリーレン基及びビフェニルやターフェニル等の鎖状多環式芳香族炭化水素由来のアリーレン基等が包含される。
該アリーレン基には、各種の置換基が結合していてもよい。
【００４６】
本発明では、前記シリコーン樹脂としてストレートシリコーン樹脂を用いることができる。このようなものとしては、ＫＲ２７１、ＫＲ２７２、ＫＲ２８２、ＫＲ２５２、ＫＲ２５５、ＫＲ１５２（信越化学工業社製）、ＳＲ２４００、ＳＲ２４０６（東レダウコーニングシリコーン社製）などが挙げられる。
【００４７】
本発明では、前記シリコーン樹脂として変性シリコーン樹脂を用いることができる。このようなものとしては、エポキシ変性シリコーン、アクリル変性シリコーン、フェノール変性シリコーン、ウレタン変性シリコーン、ポリエステル変性シリコーン、アルキッド変性シリコーンなどが挙げられる。
【００４８】
上記変性シリコーン樹脂の具体例としては、エポキシ変性物：ＥＳ−１００１Ｎ、アクリル変性シリコーン：ＫＲ−５２０８、ポリエステル変性物：ＫＲ−５２０３、アルキッド変性物：ＫＲ−２０６、ウレタン変性物：ＫＲ−３０５（以上、信越化学工業社製）、エポキシ変性物：ＳＲ２１１５、アルキッド変性物：ＳＲ２１１０（東レダウコーニングシリコーン社製）などが挙げられる。
【００４９】
本発明で用いる前記シリコーン樹脂には、アミノシランカップリング剤を適量（０．００１〜３０重量％）含有させることができるが、このようなものとしては以下のようなものが挙げられる。
【００５０】
【化３】

【００５１】
更に、本発明では、高抵抗被覆層Ａ、及び抵抗被覆層Ｂを構成する樹脂として、以下に示すものを単独または上記シリコーン樹脂と混合して使用することも可能である。
ポリスチレン、クロロポリスチレン、ポリ−α−メチルスチレン、スチレン−クロロスチレン共重合体、スチレン−プロピレン共重合体、スチレン−ブタジエン共重合体、スチレン−塩化ビニル共重合体、スチレン−酢酸ビニル共重合体、スチレン−マレイン酸共重合体、スチレン−アクリル酸エステル共重合体（スチレン−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−アクリル酸オクチル共重合体、スチレン−アクリル酸フェニル共重合体等）、スチレン−メタクリル酸エステル共重合体（スチレン−メタクリル酸メチル共重合体、スチレン−メタクリル酸エチル共重合体、スチレン−メタクリル酸ブチル共重合体、スチレン−メタクリル酸フェニル共重合体等）、スチレン−α−クロルアクリル酸メチル共重合体、スチレン−アクリロニトリル−アクリル酸エステル共重合体などのスチレン系樹脂、エポキシ樹脂、ポリエステル樹脂、ポリエチレン樹脂、ポリプロピレン樹脂、アイオノマー樹脂、ポリウレタン樹脂、ケトン樹脂、エチレン−エチルアクリレート共重合体、キシレン樹脂、ポリアミド樹脂、フェノール樹脂、ポリカーボネート樹脂、メラミン樹脂など。
【００５２】
高抵抗被覆層Ａ及び低抵抗被覆層Ｂの抵抗率は、導電性微粉末を被覆樹脂層に添加することにより調整できる。該導電性微粉末としては、導電性ＺｎＯ、Ａｌ等の金属又は金属酸化物粉、種々の方法で調製されたＳｎＯ_２又は種々の元素をドープしたＳｎＯ_２、ＴｉＢ_２、ＺｎＢ_２、ＭｏＢ_２等のホウ化物、炭化ケイ素、ポリアセチレン、ポリパラフェニレン、ポリ（パラ−フェニレンスルフィド）ポリピロール、ポリエチレン等の導電性高分子、ファーネスブラック、アセチレンブラック、チャネルブラック等のカーボンブラック等が挙げられる。
【００５３】
これらの導電性微粉末は、以下の方法、即ち、コーティングに使用する溶媒、あるいは被覆用樹脂溶液に導電性微粉末を投入後、ボールミル、ビーズミルなどメディアを使用した分散機、あるいは高速回転する羽根を備えた攪拌機を使用することによって均一に分散することができる。
【００５４】
又、高抵抗被覆層Ａや低抵抗被覆層Ｂの抵抗率の調整は、キャリア粒子上に被覆される被覆層Ａや被覆層Ｂの膜厚の制御によっても可能である。
【００５５】
高抵抗被覆層Ａの膜厚みは、好ましくは０．０５μｍ以上、より好ましくは、０．１μｍ以上に形成される。被覆層Ａを均一に塗布するためには、被覆用樹脂を希釈して、溶媒中の樹脂を固形分を出来るだけ少なくして、時間をかけてキャリア芯材粒子の表面を塗布することが望ましい。
【００５６】
低抵抗被覆層Ｂの厚みは、好ましくは０．０２〜１μｍ、より好ましくは０．０３〜０．８μｍに形成される。
【００５７】
高抵抗被覆層Ａや低抵抗被覆層Ｂの厚みはきわめて薄いので、これらの被覆層を有するキャリア粒子から構成されるキャリアの重量平均粒径Ｄｗ、粒度分布と、芯材粒子からなるキャリア芯材の重量平均粒径Ｄｗ、粒度分布は実質的に同じである。
【００５８】
本発明においては、磁性材料等を粉砕し、その粉砕物粒子を所定の粒径が得られるように分級することによりキャリア芯材を作製し、この分級により得られたキャリア芯材の各粒子の表面に前記高抵抗被覆層Ａを形成し、その上に低抵抗被覆層Ｂを形成することにより、キャリアを作製することが好ましい。又、磁性材料等を粉砕して破砕物粒子とし、該破砕物粒子の表面に前記高抵抗被覆層Ａを形成し、その上に低抵抗被覆層Ｂを形成してから、分級することによりキャリアを作製することも好ましい。
【００５９】
本発明においては、該高抵抗被覆層Ａが、キャリア芯材を希釈された樹脂で被覆することにより形成され、低抵抗被覆層Ｂが、該被覆層Ａの上に希釈された樹脂で被覆することにより形成されていることが好ましい。かかる方法を流動床型コーティング装置を用いて行えば、本発明のキャリアを効率的に作製することができる。
【００６０】
又、本発明においては、該高抵抗被覆層Ａが、乳化重合などで作製された樹脂微粒子をキャリア芯材と混合することにより、キャリア芯材表面に、樹脂微粒子を被覆率７０％以上となるように混合付着させ、さらに加熱または機械的な混合あるいは衝撃力加えることにより、溶剤を使用しないで成膜することが可能である。
尚、この場合の低抵抗被覆層Ｂは、前述したように希釈された樹脂で被覆することにより形成されていてもよければ、抵抗被覆層Ａと同様に、樹脂微粒子を必要量混合付着させ、さらに加熱または機械的な混合あるいは衝撃力加えることにより形成されていてもよい。
【００６１】
キャリア芯材表面に、樹脂微粒子を混合付着させる際に、被覆率が７０％未満であると、成膜処理した状態でもキャリア芯材表面が露出するおそれがある。被覆率は、下記（２）式により算出される。
【数２】

【００６２】
キャリア芯材の粒子表面に高抵抗被覆層Ａ、及び抵抗被覆層Ｂを形成するための方法としては、前記の方法に限定されず、スプレードライ法、浸漬法など公知の方法が使用できる。
【００６３】
前記分級には、風力分級やふるい分級（ふるい分け）や振動ふるい等が包含されるが、本発明においては、超音波発振器付きの振動ふるい機を用いることが好ましい。振動ふるい機のふるい（金網）に超音波振動を与えながら、粉砕されたキャリア芯材を分級すると、ふるい（金網）の小さな網目が詰まることを容易に防ぐことができるので、２２μｍ未満の小径粒子であっても効率よく分級することができる。
【００６４】
その粉砕物粒子を所定の粒径が得られるように分級することによりキャリア芯材を作製し、この分級により得られたキャリア芯材の各粒子の表面に前記高抵抗被覆層Ａを形成し、その上に低抵抗被覆層Ｂを形成することにより、この樹脂被覆粒子を分級することにより、キャリアを作製することも好ましい。この場合の分級においても、前記超音波発振器付きの振動ふるい機を用いることが好ましい。
【００６５】
上記金網を振動させる超音波振動は、高周波電流をＰＺＴ振動子からなるコンバータに供給して超音波振動に変換することにより発生させることが好ましい。コンバータにより発生した超音波振動は、金網に固定した共振部材に伝達され、該共振部材はその超音波振動により共振し、共振部材が固定されている金網を振動させる。金網を振動させる周波数は、好ましくは２０〜５０ｋＨｚ、より好ましくは３０〜４０ｋＨｚである。共振部材の形状は、金網を振動させるのに適した形状であればよく、通常はリング状である。金網を振動させる振動方向は、垂直方向が好ましい。
【００６６】
本発明で用いる超音波発振器付きの振動ふるい機は、上述したように、共振リングによって超音波振動を金網面に伝える構造を有することが好ましい。
図１に、好ましい超音波発振器付振動ふるい機の構造の一例を示す。図１において、１は振動ふるい器、２は円筒容器、３はスプリング、４はベース（支持台）、５は金網、６は共振リング、７は高周波電流ケーブル、８はコンバータ、９はリング状フレームを示す。図１に示した超音波発振器付振動ふるい器（円形ふるい機）を作動させるには、ケーブル７を介して高周波電流をコンバータ８に供給する。コンバータ８に供給された高周波電流は超音波振動に変換される。コンバータ８で発生した超音波振動は、そのコンバータ８が固定されている共振リング８及びそれに連設するリング状フレーム９を垂直方向に振動させる。この共振リング６の振動により、共振リング６とフレーム９に固定されている金網５が垂直方向に振動する。超音波発振器付きの振動ふるい機は販売されており、例えば、晃栄産業（株）より製品名「ウルトラソニック」として入手可能である。
【００６７】
本発明の現像剤は、少なくとも結着樹脂と着色剤を含むトナー粒子からなるトナーと、前述した特定範囲の粒径分布、特定範囲の抵抗値、および特定範囲の磁気特性を有する小粒径キャリアとが少なくとも混合されている。本発明で用いるトナー粒子の重量平均粒径Ｄｔは８μｍ以下であり、６μｍ以下であることが好ましい。トナー粒子の重量平均粒径が８μｍを超えると、特に、粒状性、および地汚れの良好な現像剤を得ることができない虞がある。
尚、本明細書におけるトナー粒子の重量平均粒径Ｄｔの測定は、コールターカウンターなどを使用して測定することができる。
【００６８】
本発明で用いられるトナー粒子は、熱可塑性樹脂を主成分とする結着樹脂中に、着色剤、微粒子、そして帯電制御剤、離型剤等を含有したものであり、本発明においては、上記重量平均粒径を有するものであれば、重合法、造粒法などの各種の製法によって作製された不定形または球形のトナーを用いることができる。また、磁性トナー及び非磁性トナーのいずれも使用可能である。
【００６９】
本発明で用いられるトナーを構成する結着樹脂（バインダー）は特に限定されないが、次に説明するものが、単独あるいは混合して好ましく使用される。
【００７０】
スチレン系樹脂として、ポリスチレン、ポリビニルトルエン等のスチレン及びその置換体の単重合体、スチレン−ｐ−クロルスチレン共重合体、スチレン−プロピレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−メタアクリル酸メチル共重合体、スチレン−メタアクリル酸エチル共重合体、スチレン−メタアクリル酸ブチル共重合体、スチレン−α−クロルメタアクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−マレイン酸共重合体、スチレン−マレイン酸エステル共重合体等のスチレン系共重合体；アクリル系バインダーとして、ポリメチルメタクリレート、ポリブチルメタクリレーが挙げられ、その他、ポリ塩化ビニル、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリエステル、ポリウレタン、エポキシ樹脂、ポリビニルブチラール、ポリアクリル酸樹脂、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、脂肪族または脂肪族炭化水素樹脂、芳香族系石油樹脂、塩素化パラフィン、パラフィンワックスなどが挙げられる。
【００７１】
又、ポリエステル樹脂は、スチレン系やアクリル系樹脂に比して、トナーの保存時の安定性を確保しつつ、より溶融粘度を低下させることが可能である。このようなポリエステル樹脂は、例えば、アルコールとカルボン酸との重縮合反応によって得ることができる。
【００７２】
上記アルコールとしては、ポリエチレングリコール、ジエチレングリコール、トリエチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，４−プロピレングリコール、ネオペンチルグリコール、１，４−ブテンジオールなどのジオール類、１，４−ビス（ヒドロキシメチル）シクロヘキサン、ビスフェノールＡ、水素添加ビスフェノールＡ、ポリオキシエチレン化ビスフェノールＡ、ポリオキシプロピレン化ビスフェノーＡなどのエーテル化ビスフェノール類、これらを炭素数３〜２２の飽和もしくは不飽和の炭化水素基で置換した２価のアルコール単位体、その他の２価のアルコール単位体、ソルビトール、１，２，３，６−ヘキサンテトロール、１，４−ソルビタン、ペンタエスリトールジペンタエスリトール、トリペンタエスリトール、蔗糖、１，２，４−ブタントリオール、１，２，５−ペンタントリオール、グリセロール、２−メチルプロパントリオール、２−メチル−１，２，４−ブタントリオール、トリメチロールエタン、トリメチロールプロパン、１，３，５−トリヒドロキシメチルベンゼン等の三価以上の高アルコール単量体が挙げられる。
【００７３】
前記ポリエステル樹脂を得るために用いられるカルボン酸としては、例えばパルミチン酸、ステアリン酸、オレイン酸等のモノカルボン酸、マレイン酸、フマール酸、メサコン酸、シトラコン酸、テレフタル酸、シクロヘキサンジカルボン酸、コハク酸、アジピン酸、セバチン酸、マロン酸、これらを炭素数３〜２２の飽和もしくは不飽和の炭化水素基で置換した２価の有機酸単量体、これらの酸の無水物、低級アルキルエステルとリノレイン酸からの二量体、１，２，４−ベンゼントリカルボン酸、１，２，５−ベンゼントリカルボン酸、２，５，７−ナフタレントリカルボン酸、１，２，４−ナフタレントリカルボン酸、１，２，４−ブタントリカルボン酸、１，２，５−ヘキサントリカルボン酸、１，３−ジカルボキシル−２−メチル−２−メチレンカルボキシプロパン、テトラ（メチレンカルボキシル）メタン、１，２，７，８−オクタンテトラカルボン酸エンボール三量体酸、これらの酸の無水物等の三価以上の多価カルボン酸単量体が挙げられる。
【００７４】
エポキシ系樹脂として、ビスフェノールＡとエポクロルヒドリンとの重縮合物等があり、例えば、エポミックＲ３６２、Ｒ３６４、Ｒ３６５、Ｒ３６６、Ｒ３６７、Ｒ３６９（以上、三井石油化学工業（株）製）、エポトートＹＤ−０１１、ＹＤ−０１２、ＹＤ−０１４、ＹＤ−９０４、ＹＤ−０１７、（以上、東都化成（株）製）エポコ−ト１００２、１００４、１００７（以上、シェル化学社製）等の市販のものが挙げられる。
【００７５】
本発明で用いるトナーを構成する着色剤としては、カーボンブラック、ランプブラック、鉄黒、群青、ニグロシン染料、アニリンブルー、フタロシアニンブルー、ハンザイエローＧ、ローダミン６Ｇ、レーキ、カルコオイルブルー、クロムイエロー、キナクリドン、ベンジジンイエロー、ローズベンガル、トリアリルメタン系染料、モノアゾ系、ジスアゾ系、染顔料など、従来公知のいかなる染顔料をも単独あるいは混合して使用し得る。
【００７６】
本発明においては、トナーに磁性体を含有させて磁性トナーとすることも可能である。磁性体としては、鉄、コバルトなどの強磁性体、マグネタイト、ヘマタイト、Ｌｉ系フェライト、Ｍｎ−Ｚｎ系フェライト、Ｃｕ−Ｚｎ系フェライト、Ｎｉ−Ｚｎフェライト、Ｂａフェライトなどの微粉末が使用できる。
【００７７】
また本発明で用いるトナーにおいては、トナーの摩擦帯電性を充分に制御する目的で、いわゆる帯電制御剤、例えばモノアゾ染料の金属錯塩、ニトロフミン酸およびその塩、サリチル酸、ナフトエ塩、ジカルボン酸のＣｏ、Ｃｒ、Ｆｅ等の金属錯体アミノ化合物、第４級アンモニウム化合物、有機染料などを含有させることができる。
【００７８】
また本発明で用いるトナーには、必要に応じて離型剤を添加してもよい。
該離型剤としては、低分子量ポリプロピレン、低分子量ポリエチレン、カルナウバワックス、マイクロクリスタリンワックス、ホホバワックス、ライスワックス、モンタン酸ワックス等を単独または混合して用いることができるが、これらに限定されるものではない。
【００７９】
また本発明で用いるトナーには、添加剤を添加することができる。良好な画像を得るためには、トナーに十分な流動性を付与することが肝要である。これには、一般に流動性向上材として疎水化された金属酸化物の微粒子や、滑剤などの微粒子を外添することが有効であり、金属酸化物、有機樹脂微粒子、金属石鹸などを添加剤として用いることが可能である。これら添加物の具体例としては、テフロン（Ｒ）、ステアリン酸亜鉛のごとき滑剤や、酸化セリウム、炭化ケイ素などの研磨剤；例えば表面を疎水化したＳｉＯ_２、ＴｉＯ_２等の無機酸化物などの流動性付与剤；ケーキング防止剤として知られるもの、および、それらの表面処理物などが挙げられる。トナーの流動性を向上させるためには、特に、疎水性シリカが好ましく用いられる。
【００８０】
本発明の現像剤においては、キャリアに対するトナーの被覆率は、２５％〜９５％が好ましく、３０〜９０％がより好ましい。トナー被覆率が２５％以下になると画像濃度が低下傾向となる。また９５％以上になると地汚れが増え、粒状性もやや悪くなる。
【００８１】
上記キャリアに対するトナーの被覆率は、下記（３）式で算出される。
【数３】
被覆率（％）＝（Ｗｔ／Ｗｃ）×（ρｃ／ρｔ）×（Ｄｃ／Ｄｔ）×（１／４）×１００　　（３）
（３）式中、Ｄｃはキャリアの重量平均粒径（μｍ）、Ｄｔはトナーの重量平均粒径（μｍ）、Ｗｔはトナーの重量（ｇ）、Ｗｃはキャリアの重量（ｇ）、ρｔはトナー真密度（ｇ／ｃｍ^３）、ρｃはキャリア真密度（ｇ／ｃｍ^３）をそれぞれ表す。トナーの真比重は、１．２５ｇ／ｃｍ^３とした。
【００８２】
本発明の現像剤においては、キャリアに対するトナーの被覆率が５０％のときのトナー帯電量が、１０〜３５μｃ／ｇであることが好ましい。かかる現像剤を使用すると、キャリア付着、エッジ効果、画像濃度、粒状性、および地汚れ、いずれの品質も良好な現像剤が得られる。帯電量が１０μｃ／ｇ以下になると地汚れが増える傾向となり、３５μｃ／ｇ以上になると、画像濃度が低下傾向となり、またエッジ効果も増える。
【００８３】
本発明の現像方法は、前記した本発明の現像剤を用いて潜像を現像する方法である。該方法においては、外部から印加する現像バイアスとして、直流電圧に交流電圧を重畳させた交流電圧を印加すると、充分な画像濃度が得られる。特に、ハイライトの粒状性が良好となる。更に、現像バイアスとして、直流電圧のみを印加すると、キャリア付着、エッジ効果が大幅に改善され、また、地汚れ対する余裕度が大きくなるため、キャリアに対するトナー被覆率を上げること、またトナー帯電量、および現像バイアスを下げることが可能となり、画像濃度アップを図ることが出来るので好ましい。
【００８４】
本発明の電子写真用現像剤容器は、前記した本発明の現像剤が収納させたものである。この場合の容器としては、従来公知の各種のものを用いることができる。
【００８５】
本発明の画像形成装置は、その現像容器として、前記した本発明の現像容器を用いたものである。この場合の画像形成装置としては、従来公知の各種のものを用いることができる。
【００８６】
【実施例】
以下本発明について実施例に基づき詳細に説明する。但し、これらの実施例は本発明をなんら限定するものではない。尚、以下において、「部」は重量部を表わす。
まず、実施例、比較例で使用するトナーＩ、トナーＩＩを作製した。
【００８７】
トナーＩ
ポリエステル樹脂１００部と、キナクリドン系マゼンタ顔料３．５部と、含フッ素４級アンモニウム塩４部とをブレンダーにて十分に混合した後、２軸式押出機にて溶融混練し、押出して放冷した後カッターミルで粗粉砕し、ついでジェット気流式微粉砕機で微粉砕し、さらに風力分級機を用いて分級して、重量平均平均粒径Ｄｔ７．６μｍ（表２に示す。）、真比重１．２５ｇ／ｃｍ^３のトナー母粒子を得た。更に、このトナー母粒子１００部に対して、疎水性シリカ微粒子（Ｒ９７２：日本アエロジル社製）０．８部を加え、ヘンシェルミキサーで混合して、トナーＩを得た。
【００８８】
トナーＩＩ
上記トナーＩと同様な方法で、重量平均粒径Ｄｔ５．８μｍ（表２に示す。）、真比重１．２５ｇ／ｃｍの母体トナーを作製し、これに疎水性シリカ微粒子（Ｒ９７２）１．０部を加え、ヘンシェルミキサーで混合して、トナーＩＩを得た。
【００８９】
実施例１
シリコーン樹脂（ＳＲ２４１１、トーレダウコーニングシリコーン社製）を希釈して、シリコーン樹脂溶液（固形分：２．５％）を作製した。
次に、流動床型コーティング装置を用いて、表１に示した性状を持つキャリア芯材粒子１（ＣｕＺｎ系フェライト、１ＫＯｅの磁気モーメント４３ｅｍｕ／ｇ）５Ｋｇの各粒子表面上に、上記のシリコーン樹脂溶液を、９０℃の雰囲気下で約２０ｇ／ｍｉｎの割合で塗布し、この状態のキャリアを少量サンプリングして、更に２４０℃で２時間加熱した。蛍光Ｘ線により膜厚を測定したところ、０．１μｍのシリコーン樹脂からなる高抵抗被覆層Ａが形成されていた。
【００９０】
更にシリコーン固形分１００部に対し、カーボン７部、アミノシランカップリング剤、Ｈ_２ＮＣＨ_２ＣＨ_２ＮＨＣＨ_２Ｓｉ（ＯＣＨ_３）_３を３部添加して、高抵抗被覆層Ａと低抵抗被覆層Ｂの合計膜厚０．５８μｍの被覆層を形成し、キャリアＡを得た。
被覆層Ａの抵抗は、ＬｏｇＲ_Ａ＝１６．１Ωｃｍ、被覆層Ａの上に被覆層Ｂを積層した被覆層の抵抗値は、ＬｏｇＲ＝１０．５Ωｃｍであった。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＡのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【００９１】
前記トナーＩと、キャリアＡを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、ハイライトの粒状性、キャリア付着、エッジ効果、画像濃度、地汚れ、２０Ｋラン後の地汚れを試験し、画像の品質を確認し、その信頼性を調べた。結果を、表２に示す。
【００９２】
【表１】

【００９３】
【表２】

【００９４】
画像はイマジオカラー５０００（リコー製デジタルカラー複写機・プリンター複合機）を使用し、次の現像条件で作製した。
・現像ギャップ（感光体−現像スリーブ）：０．４０ｍｍ
・ドクターギャップ（現像スリーブ−ドクター）：０．７０ｍｍ
・感光体線速度２４５ｍｍ／ｓｅｃ
・（現像スリーブ線速度／感光体線速度）＝１．５０
・書込み密度：６００ｄｐｉ
・帯電電位（Ｖｄ）：−７００Ｖ
・画像部（べた原稿）にあたる部分の露光後の電位（Ｖ／）：−１００Ｖ
・現像バイアス：ＤＣ−５００Ｖ／交流バイアス成分：２ＫＨＺ、−２００Ｖ〜−１０００Ｖ、５０％ｄｕｔｙ
【００９５】
ハイライトの粒状性、エッジ効果、画像濃度、地汚れについての品質評価を下記基準に従って転写紙上で行い、キャリア付着についての品質評価を下記基準に従って、現像後転写前の感光体上で行った。又、２０Ｋラン後の地汚れについて下記基準で行い、信頼性の評価を行った。
【００９６】
（１）ハイライトの粒状性：
ランク見本を作製し１０段階で評価した。ランク１０が最良である。
【００９７】
（２）キャリア付着：
キャリア付着が発生すると、感光体ドラムや定着ローラーの傷の原因となり、画像品質の低下を招く。キャリア付着しても一部のキャリアしか紙に転写して来ない為、キャリア付着を直接感光体ドラム上で観察し評価した。また、画像パターンによってキャリア付着が発生する態様が異なる為、次の方法でキャリア付着の起こりにくさを評価した。
帯電電位（Ｖｄ）を−７００Ｖ、現像バイアス（Ｖｂ）をＤＣ−４００Ｖに固定し、地肌部（⇒未露光部）を現像し、感光体上の３０ｃｍ^２に付着したキャリアの個数を直接カウントして、キャリア付着の評価を行った。個数が少ないほどキャリア付着が起こりにくいことを表している。
この時の地肌ポテンシャルは、Ｖｂ−Ｖｄの値より３００Ｖである。
なお、現像交流バイアス印加時は、ＤＣバイアスＶｂ＝３００Ｖに対して±４００Ｖ重畳印加（周波数２ＫＨＺ、５０％ｄｕｔｙ）した。
【００９８】
（３）エッジ効果
帯電電位を−７００Ｖ、バイアス電位を−５５０Ｖ、ベタ部の電位を−１００Ｖに固定し、中間濃度の電位をＶｍとした。レーザーパワーの変調により中間濃度領域の電位を変化させ、ベタ画像部と、中間濃度領域の境界に白抜けが発生しなくなった電位を測定した。Ｖｍの絶対値が大きいほどエッジ効果が発生し難い現像剤である。
なお、交流バイアス印加の条件の際は、ＤＣバイアスに対して±４００Ｖ重畳印加（周波数２ＫＨＺ、５０％ｄｕｔｙ）した。
【表３】

【００９９】
（４）画像濃度：
前記現像条件における、３０ｍｍ×３０ｍｍのベタ部の中心をＸ−Ｒｉｔｅ９３８分光測色濃度計で、５個所測定し平均値を画像濃度とした。
【０１００】
（５）地汚れ：
上記現像条件における地肌部の地汚れを１０段階で評価した。
ランクが高い程地汚れが少なく、ランク１０が最良である。
【０１０１】
（６）２０Ｋラン後の地汚れ
初期画像出しに使用したマゼンタトナーＡ、またはトナーＢを補給しながら画像面積率６％の文字画像チャートで２万枚のランニング評価を行なった。上記現像条件における地肌部の地汚れを１０段階で評価した。ランクが高い程地汚れ少なく、ランク１０が最良である。
【０１０２】
実施例２
低抵抗被覆層Ｂのカーボン量を３．８部にしたこと以外は、実施例１と全く同様にして、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１４．６ΩｃｍのキャリアＢを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＢのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１０３】
前記トナーＩと、キャリアＢを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１０４】
実施例３
低抵抗被覆層Ｂのカーボン量を５．０部、およびアミノシランカップリング剤量を２．５部にしたこと以外は、実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１３．１ΩｃｍのキャリアＣを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＣのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１０５】
前記トナーＩと、キャリアＣを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１０６】
実施例４
キャリア芯材１に替えて、２２μｍ以下の粒子の含有量が、０．３重量％である、キャリア芯材２を使用し、低抵抗被覆層Ｂのカーボン量を５．０部、およびアミノシランカップリング剤量を２．５部にしたこと以外は、実施例１と同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１３．１ΩｃｍのキャリアＤを得た。
キャリア芯材２の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材２の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＤのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１０７】
前記トナーＩと、キャリアＤを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１０８】
比較例１
高抵抗被覆層Ａを形成せず、低抵抗被覆層Ｂのみを、実施例１の合計膜厚と同じ厚さになるように形成したこと以外は実施例１と全く同様な方法で、被覆層Ｂの膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１０．５ΩｃｍのキャリアＥを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＥのＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ｂの膜厚（μｍ）をまとめて表１に示す。
【０１０９】
前記トナーＩと、キャリアＥを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１１０】
比較例２
４４μｍ以下の粒子の含有量が６９％である、芯材３を使用したこと以外は、実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１０．６ΩｃｍのキャリアＦを得た。
キャリア芯材３の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材３の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＦのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１１１】
前記トナーＩと、キャリアＦを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１１２】
比較例３
２２μｍ以下の粒子の含有量が、６．７％であるキャリア芯材４を使用したこと以外は、実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１０．４ΩｃｍのキャリアＧを得た。
キャリア芯材４の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材４の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＧのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１１３】
前記トナーＩと、キャリアＧを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１１４】
比較例４
磁気モーメントが３５ｅｍｕ／ｇのキャリア芯材５を使用したこと以外は実施例１と全く同様な方法で、キャリアＨを作製した。実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１０．５ΩｃｍのキャリアＨを得た。
キャリア芯材５の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材５の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＨのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１１５】
前記トナーＩと、キャリアＨを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１１６】
比較例５
高抵抗被覆層Ａを形成しないこと除いては、実施例２と全く同様な方法で、被覆層Ｂの合計膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１４．７ΩｃｍのキャリアＩを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＩのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ｂの膜厚（μｍ）をまとめて表１に示す。
【０１１７】
前記トナーＩと、キャリアＩを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１１８】
実施例５
低抵抗被覆層Ｂのカーボン量を８．５部、アミノシランカップリング剤量を５．０部にしたこと以外は、実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５９μｍ、キャリア抵抗ＬｏｇＲが９．４ΩｃｍのキャリアＪを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＢのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１１９】
前記トナーＩと、キャリアＪを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２０】
実施例６
低抵抗被覆層Ｂのカーボン量を２．５部に減らし、アミノシランカップリング剤量を２．０部にしたこと以外は、実施例１と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５９μｍ、キャリア抵抗ＬｏｇＲが１５．４ΩｃｍのキャリアＫを得た。
キャリア芯材１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＫのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１２１】
前記トナーＩと、キャリアＫを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２２】
実施例７
磁気モーメントが６３ｅｍｕ／ｇのキャリア芯材６を使用したこと以外は、実施例３と全く同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１３．２ΩｃｍのキャリアＬを得た。
キャリア芯材６の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材６の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＬのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１２３】
前記トナーＩと、キャリアＬを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２４】
実施例８
アミノシランカップリング剤の含有量を２．５部から４部に変更したこと以外は、実施例７と全く同様な方法で、７．６μｍトナーが５０％被覆したときのトナー帯電量が４０μｃ／ｇ、被覆層Ａと被覆層Ｂの合計膜厚が０．５６ミクロン、キャリア抵抗ＬｏｇＲが１３．２ΩｃｍのキャリアＭを得た。
キャリア芯材６の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材６の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＭのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１２５】
前記トナーＩと、キャリアＬを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２６】
実施例９
アミノシランカップリング剤の含有量を２．５部から１部に変更したこと以外は実施例７と全く同様な方法で、７．６μｍトナーが５０％被覆したときのトナー帯電量が８μｃ／ｇ、被覆層Ａと被覆層Ｂの合計膜厚が０．５８ミクロン、キャリア抵抗ＬｏｇＲが１３．２ΩｃｍのキャリアＮを得た。
キャリア芯材６の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材６の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＮのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１２７】
前記トナーＩと、キャリアＬを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２８】
実施例１０
実施例７で得たキャリアＬを使用して、７．６μｍトナーの被覆率が２０％となるように現像剤を調整した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１２９】
実施例１１
実施例７で得たキャリアＬを使用して、７．６μｍトナーの被覆率が１００％となるように現像剤を調整した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１３０】
実施例１２
磁気モーメントが７８ｅｍｕ／ｇのキャリア芯材７を使用したこと以外は、実施例１と全く同様に、被覆層Ａと被覆層Ｂの合計膜厚が０．５９ミクロン、キャリア抵抗ＬｏｇＲが１０．５ΩｃｍのキャリアＱを得た。
キャリア芯材７の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材７の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＱのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１３１】
前記トナーＩと、キャリアＱを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１３２】
実施例１３
キャリア芯材１に対して、ポリメチルメタクリレートの樹脂微粒子（ＭＰ１４５０，０．２５μｍ、綜研化学製）を、被覆率が８０％になるように乾式混合し、さらに、熱と機械的衝撃力を加えてキャリア芯材１の表面に成膜させ、高抵抗被覆層Ａを形成した。その上に実施例１と全く同様に、低抵抗被覆層Ｂを形成し、被覆層Ａと被覆層Ｂの合計膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１０．５ΩｃｍのキャリアＲを得た。
【０１３３】
前記トナーＩと、キャリアＲを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１３４】
実施例１４
表１に示す特性をもったマグネタイトからなるキャリア芯材８を使用して、実施例８と同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１３．２ΩｃｍのキャリアＳを得た。
キャリア芯材８の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材８の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＳのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１３５】
前記トナーＩと、キャリアＳを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１３６】
比較例６
高抵抗被覆層Ａを成形しないこと以外は、実施例１４と全く同様に、被覆層Ｂの膜厚が０．５８μｍ、キャリア抵抗ＬｏｇＲが１３．２ΩｃｍのキャリアＴを得た。
キャリア芯材８の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材８の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＴのＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１３７】
前記トナーＩと、キャリアＴを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１３８】
実施例１５
表１に示す特性をもった鉄粉芯材からなるキャリア芯材９を使用して、実施例８と同様な方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１３．３ΩｃｍのキャリアＵを得た。
キャリア芯材９の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材９の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＵのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１３９】
前記トナーＩと、キャリアＵを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４０】
比較例７
高抵抗被覆層Ａを成形しないこと以外は、実施例１５と全く同様な方法で、被覆層Ｂの膜厚が０．５７μｍ、キャリア抵抗ＬｏｇＲが１３．３ΩｃｍのキャリアＶを得た。
キャリア芯材９の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材９の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＶのＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ｂの膜厚（μｍ）をまとめて表１に示す。
【０１４１】
前記トナーＩと、キャリアＶを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４２】
実施例１６
マグネタイト粒子を分散させた樹脂からなる、磁気モーメントが５５ｅｍｕ／ｇのキャリア芯材１０を使用し、低抵抗被覆層Ｂのカーボン量を４．０部としたこと以外は、実施例８と同様の方法で、被覆層Ａと被覆層Ｂの合計膜厚が０．５９μｍ、キャリア抵抗ＬｏｇＲが１３．３ΩｃｍのキャリアＷを得た。
キャリア芯材１０の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１０の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＷのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１４３】
前記トナーＩと、キャリアＷを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４４】
比較例８
高抵抗被覆層Ａを成形しないこと以外は、実施例１６と全く同様な方法で、被覆層Ｂの膜厚が０．５９μｍ、キャリア抵抗ＬｏｇＲが１３．３ΩｃｍのキャリアＸを得た。
キャリア芯材の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＸのＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ｂの膜厚（μｍ）をまとめて表１に示す。
【０１４５】
前記トナーＩと、キャリアＸを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４６】
実施例１７
実施例１で得たキャリアＡに、前記トナーＩＩ（５．８ミクロントナー）を混合攪拌して現像剤を作製した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４７】
実施例１８
２２ミクロン以下の粒子の含有率が６．７％であるキャリア芯材４を、超音波振動子の設置された振動篩い機で分級し、２２μｍ以下の粒子の含有比率を２．８％まで減らしたキャリア芯材１１を使用して、実施例１とまったく同じ方法でキャリアＹを得た。
キャリア芯材１１の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１１の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＹのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１４８】
前記トナーＩと、キャリアＹを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１４９】
実施例１９
実施例１８で得たキャリア芯材１１をさらに、共振リングの設置された超音波振動ふるいを用いて、分級し、２２μｍ以下の粒子の含有比率を０．２％まで減らしたキャリア芯材１２を作製した。これを用い実施例１と同様の方法でキャリアＺを得た。
キャリア芯材１２の重量平均粒径Ｄｗ、粒径４４μｍ以下の粒子の含有割合（重量％）、粒径２２μｍ以下の粒子の含有割合（重量％）、キャリア芯材１２の１ＫＯｅにおける磁気モーメント（ｅｍｕ／ｇ）、キャリアＺのＬｏｇＲ_Ａ、ＬｏｇＲ、カーボン量（部）、アミノシランカップリング剤量（部）、被覆層Ａと被覆層Ｂの合計膜厚（μｍ）をまとめて表１に示す。
【０１５０】
前記トナーＩと、キャリアＺを用いて、現像剤を製造した。
得られた現像剤を用いて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１５１】
実施例２０
前記トナーＩと、キャリアＡを用いて実施例１で得た現像剤を用い、印加バイアス（ＤＣバイアスにＡＣバイアスを重畳）をＤＣバイアスに変えて画像形成を行い、実施例１と同様に、品質評価、信頼性の評価を行った。結果を、表２に示す。
【０１５２】
【発明の効果】
本発明の電子写真現像用現像剤を提供は、ドット再現性が良く、ハイライト部の粒状性が良好で、エッジ効果が少なく、高画像濃度であって、地汚れが少ない高画質が得られ、かつ、キャリア付着が起き難い。
【図面の簡単な説明】
【図１】超音波発振器付きの振動ふるい機の説明構造図を示す。
【図２】キャリアの電気抵抗率の測定に用いる抵抗測定セルの斜視図である。
【符号の説明】
１　振動ふるい機
２　円筒容器
３　スプリング
４　ベース
５　金網
６　共振リング
７　ケーブル
８　コンバータ（振動子）
９　リング状フレーム
１１　セル
１２　電極
１３　キャリア[0001]
[Industrial applications]
The present invention relates to a developer for electrophotographic development, an electrophotographic development method using the developer for electrophotography, and a method for producing a carrier for electrophotographic development used for the developer for electrophotography development.
[0002]
[Prior art]
The electrophotographic development system includes a so-called one-component development system that uses only toner as a main component, and the toner and a glass bead, a magnetic carrier, or a coat carrier whose surface is coated with a resin or the like. There is a two-component developing method that is used by mixing.
[0003]
Since the two-component developing method uses a carrier, the frictional charging area with respect to the toner is large, so that the charging characteristics are stable as compared with the one-component method, and it is advantageous to maintain high image quality for a long time. . Further, since the toner supply capacity to the developing area is high, it is often used particularly for high-speed machines. Also, in a digital electrophotographic system in which an electrostatic latent image is formed on a photoreceptor by a laser beam or the like and the latent image is visualized, a two-component developing method utilizing the above-mentioned features is widely used. I have.
[0004]
In the field of the two-component development system, in recent years, the minimum unit (1 dot) of the latent image has been minimized and the density has been increased in order to cope with an increase in resolution, highlight reproducibility, and colorization. In particular, it has become an important issue to develop a developing system that can faithfully develop these latent images (dots).
[0005]
Therefore, for the purpose of faithfully developing a latent image (dot), various proposals have been made from both sides of a process and a developer (toner, carrier). For example, on the process side, issues such as approaching the development gap, thinning the photoconductor, and reducing the diameter of the writing beam are being studied.
[0006]
On the other hand, as a developer, use of a toner having a small particle diameter has been studied in order to faithfully develop a latent image (dot), that is, to greatly improve dot reproducibility.
[0007]
However, the developer containing the small particle size toner has problems to be solved, such as generation of background stain and insufficient image density. In the case of a full-color toner having a small particle size, a resin having a low softening point is used in order to obtain a sufficient color tone. As a result, as compared with the case of black toner, the amount of spent on the carrier is increased, and there is a problem that the toner charge amount is reduced, the toner is scattered, and the background is easily stained.
[0008]
In order to solve the problem of the developer containing such a small particle size toner, it has been proposed to use a small particle size carrier. For example, the use of a small particle size carrier has the following advantages.
(1) Since the surface area is large, sufficient frictional charge can be given to each toner, and the generation of low charge amount toner and reverse charge amount toner is small. As a result, background stains are less likely to occur, and toner remnants and bleeding around the dots are reduced and dot reproducibility is improved.
(2) Since the surface area is large and the background stain is unlikely to occur, the average charge amount of the toner can be reduced, and a sufficient image density can be obtained. Therefore, the small particle size carrier can make up for the problem at the time of using the small particle size toner, and is particularly effective for extracting the advantage of the small particle size toner.
(3) The small particle size carrier forms a dense magnetic brush and has good fluidity, so that it has a feature that ear marks are hardly generated on an image.
[0009]
However, the conventional carrier having a small particle diameter is liable to adhere to the carrier, causing damage to the photoreceptor and fixing roller.
Usually, there are two types of carrier deposition. That is, the counter charge of the toner is accumulated in the carrier, and the other is that the carrier is induced by the electric field between the photoconductor and the developing sleeve due to the low carrier resistance, and the carrier is charged. . In each case, the charged carriers are attracted to the electric field, shake off the magnetic binding force, and adhere to the photoconductor.
On the other hand, the carrier receives a magnetic binding force from the magnet of the developing sleeve, thereby preventing the carrier from adhering. However, since the magnetic binding force is proportional to the cube of the particle size of the carrier, when the particle size of the carrier is small, the magnetic binding force is rapidly reduced, and the carrier adhesion is greatly increased. In addition, the carrier core material generally has a considerably low resistance. For this reason, if the resin film is uneven and has a thin portion, or if a portion of the carrier core material is exposed, the substantial resistance of the carrier is reduced. Since a small particle size carrier has a very small magnetic binding force, a decrease in resistance in particular increases carrier adhesion.
[0010]
In order to prevent the occurrence of the carrier adhesion, for example, Japanese Patent Application Laid-Open No. 4-198946 proposes treating the surface of a carrier core material in advance with a silane coupling agent or the like. However, in this method, although the strength of the resin film is increased, a non-uniform region of the film is also generated, so that the resistance is substantially reduced, and it has been difficult to prevent carrier adhesion due to charge induction.
[0011]
Also, the thicker the film, the higher the carrier resistance, and it is possible to considerably improve the carrier adhesion. However, on the other hand, since the edge effect becomes strong and the image density decreases, it has not been possible to solve the problem of achieving both high image quality and high reliability by using a small particle size carrier.
[0012]
[Problems to be solved by the invention]
The development of the present invention has good dot reproducibility, good granularity in highlights, little edge effect, high image density, high image quality with little background smear, and less likely to cause carrier adhesion. The purpose is to provide an agent. Another object of the present invention is to provide a developer container containing the developer, and to provide an image forming apparatus equipped with the developer container. Still another object of the present invention is to provide a method for producing the carrier.
[0013]
[Means for Solving the Problems]
The present inventors have examined the particle size of the carrier adhering to the photoreceptor. As a result, the carrier having a smaller particle size tends to adhere preferentially to the original particle size distribution. The present inventors have found that the proportion of particles having a particle size of less than 22 μm is overwhelmingly large in the carrier, and that the resistance of the carrier is very important in order to reduce carrier adhesion, and arrived at the present invention.
According to the present invention, the following invention is provided.
(1) In an electrophotographic developer obtained by mixing at least toner particles having a weight average particle diameter Dt of at most 8 μm containing at least a binder resin and a colorant, and a carrier, the weight of a carrier core material constituting the carrier The average particle size Dw is 20 to 45 μm, the content of particles having a particle size of 44 μm or less in the carrier core material is 80% by weight or more, and the content ratio of particles having a particle size of 22 μm or less is 5.0% by weight or less. And a magnetic moment at 1 KOe of the carrier core material is 40 emu / g or more, and a high resistance coating layer A is laminated on the surface of the carrier core material, and a high resistance coating layer is formed on the high resistance coating layer A. A developer for electrophotographic development, wherein a low-resistance coating layer B having a lower resistance than A is laminated.
(2) The logarithm (LogR) of the resistance value of the high resistance coating layer A _A ) Is 15.5 Ωcm or more (DC resistance of 500 V) and the logarithm of the resistance value of the resistance coating layer B (LogR) _B The developer for electrophotographic development according to the above (1), wherein the developer is 10.0 Ωcm to 15.0 Ωcm (DC resistance of 500 V).
(3) The logarithm (LogR) of the resistance value of the high resistance coating layer A _A ) Is 15.5 Ωcm or more (DC resistance of 500 V) and the logarithm of the resistance value of the resistance coating layer B (LogR) _B The developer for electrophotographic development according to the above (1), wherein the developer is 12.0 Ωcm to 14.00 Ωcm (DC resistance of 500 V).
(4) The developer for electrophotographic development according to any one of (1) to (3), wherein the content of particles having a particle size of 22 μm or less in the carrier core material is 1% by weight or less. .
(5) The electrophotographic developer according to any one of (1) to (4), wherein the carrier core material has a magnetic moment at 1 KOe of 60 emu / g or more.
(6) The developer according to any one of (1) to (4), wherein the magnetic moment of the carrier core material at 1 KOe is 76 emu / g or more.
(7) The electrophotographic development according to any one of (1) to (6), wherein the toner charge amount is 10 to 35 μc / g when the toner coverage on the carrier is 50%. Agent.
(8) The developer according to any one of (1) to (7), wherein the toner coverage is 25 to 95%.
(9) The high resistance coating layer A is formed by coating a carrier core material with a resin, and the low resistance coating layer B is formed by coating the coating layer A with a resin. The developer for electrophotographic development according to any one of the above (1) to (8).
(10) The high-resistance coating layer A is formed by mixing and adhering resin fine particles on the surface of the carrier core material so as to have a coating rate of 70% or more, and further heating or mechanically mixing or applying an impact force. The developer for electrophotographic development according to any one of the above (1) to (9), wherein
(11) The developer according to any one of (1) to (10), wherein the carrier core material is a ferrite particle.
(12) The developer according to any one of the above (1) to (10), wherein the carrier core material is magnetite particles.
(13) The developer according to any one of (1) to (10), wherein the carrier core material is iron powder particles.
(14) The developer for electrophotographic development according to any one of (1) to (10), wherein the carrier core material is a resin particle containing a magnetic material.
(15) The developer for electrophotographic development according to any one of (1) to (14), wherein the weight average particle diameter of the toner particles is 6.0 μm or less.
(16) An electrophotographic development method using the electrophotographic developer according to any one of (1) to (15).
(17) The electrophotographic developing method according to (16), wherein a DC voltage is used as a developing bias.
(18) In order to classify the carrier core material or the pulverized product particles used in the electrophotographic developer according to any one of the above (1) to (15), a vibrating sieve equipped with an ultrasonic oscillator is used. A method for producing a carrier for an electrophotographic developer, which is characterized in that:
(19) An electronic device characterized by using a vibration sieving machine with an ultrasonic oscillator for classifying the resin-coated carrier used in the electrophotographic developer according to any one of (1) to (15). A method for producing a carrier for photographic developer.
(20) The vibration sieving machine with an ultrasonic oscillator has a structure for transmitting ultrasonic vibrations to a wire mesh surface by a resonance ring installed on the sieving machine, according to the above (18) or (19). Method for producing a carrier for an electrophotographic developer.
(21) A developer container for electrophotographic development, wherein the developer for electrophotography according to any one of (1) to (15) is stored.
(22) An image forming apparatus provided with the developer container for electrophotographic development according to (21).
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The developer for an electrophotographic developer of the present invention (hereinafter, also simply referred to as a developer) is obtained by mixing at least toner particles having a small particle diameter of 8 μm or less containing at least a binder resin and a colorant, and a carrier core material. Developer. The toner particles having the small particle diameter and the binder resin will be described later.
Incidentally, the developer of the present invention includes those used in an electrostatic recording system, an electrostatic printing system and the like in addition to the electrophotographic system.
[0015]
The weight average particle diameter Dw of the carrier core material used in the present invention is from 20 to 45 μm, and more preferably from 25 to 40 μm. If the weight average particle diameter Dw of the carrier core material is larger than 45 μm, carrier adhesion is unlikely to occur, but if the toner concentration is increased in order to obtain a high image density, background contamination may easily occur. In addition, when the dot diameter of the latent image is small, the variation in dot reproducibility becomes large, and the graininess of the highlight portion may be deteriorated.
[0016]
Note that the carrier adhesion refers to a phenomenon in which the carrier adheres to an image portion or a background portion of the electrostatic latent image. The stronger the respective electric fields, the easier the carrier adheres, but the electric field is weakened by developing the toner in the image area, so that the carrier is less likely to adhere than in the background area. Even a small amount of carrier adhesion causes inconvenience such as causing damage to the photosensitive drum and the fixing roller. Therefore, it is preferable to reduce the amount as small as possible.
[0017]
The content ratio of particles having a particle size of 44 μm or less in the carrier core material is 80% by weight or more, and more preferably 85% or more. When the content ratio of the particles having a particle diameter of 44 μm or less is less than 80% by weight, the effect of the developer including the small particle diameter toner as described above, that is, the prevention of the occurrence of the background stain, the dust However, there is a possibility that effects such as good dot reproducibility with little bleeding, sufficient image density, and difficulty in producing ear traces in an image cannot be obtained.
[0018]
In this specification, the weight average particle size Dw regarding the carrier, the carrier core material and the toner is calculated based on the particle size distribution of particles measured on a number basis (the relationship between the number frequency and the particle size). .
The weight average particle diameter Dw in this case is represented by the following equation (1).
(Equation 1)
Dw = {1 /} (nD ³ )｝ × ｛Σ (nD ⁴ )｝ (1)
In the formula (1), D indicates the representative particle diameter (μm) of the particles present in each channel, and n indicates the total number of particles present in each channel.
The channel indicates a length for equally dividing the particle size range in the particle size distribution diagram. In the case of the present invention, a length of 2 μm is adopted.
The lower limit of the particle size stored in each channel was adopted as the representative particle size of the particles present in each channel.
[0019]
In the present specification, as a particle size analyzer for measuring the particle size distribution, a Microtrac particle size analyzer (Model HRA9320-X100: manufactured by Honeywell) was used.
The measurement conditions are as follows.
(1) Particle size range: 100 to 8 μm
(2) Channel length (channel width): 2 μm
(3) Number of channels: 46
[0020]
In the carrier core material used in the present invention, the content of particles having a particle size of 22 μm or less is 5.0% by weight or less, preferably 3.0% by weight or less, and more preferably 1.0% by weight or less. . When such a carrier core material is used, carrier adhesion can be effectively prevented. This is because the present inventors have found that the carrier having a small particle size tends to preferentially adhere to the original particle size distribution, and the ratio of particles having a particle size of less than 22 μm is overwhelming. This is due to the finding that there are many cases.
[0021]
Further, in the carrier core material used in the present invention, the magnetic moment at 1 KOe is 40 emu / g or more, preferably 60 emu / g or more, more preferably 76 emu / g or more. When a carrier core material having a magnetic moment of less than 40 emu / g is used, carrier adhesion may not be effectively prevented.
[0022]
The magnetic moment in this specification can be measured as follows.
Using a BH tracer (BHU-60 / manufactured by Riken Denshi Co., Ltd.), 1.0 g of carrier core material particles are packed in a cylindrical cell and set in an apparatus. The magnetic field is gradually increased and changed to 3000 Oe, then gradually reduced to zero, and then the magnetic field in the opposite direction is gradually increased to 3000 Oe. After the magnetic field is gradually reduced to zero, a magnetic field is applied in the same direction as the first. In this way, the BH curve is shown, and the magnetic moment of 1000 Oe is calculated from the figure.
[0023]
Further, the carrier core material used in the present invention has a high resistance coating layer A formed on the surface thereof, and a resistance coating layer B having a lower resistance than the high resistance coating layer A formed on the high resistance coating layer A. I have. As described above, the weight average particle diameter Dw of the carrier core material, the distribution of the particle diameter, the magnetic moment is within a specific range, and further, by providing the high resistance coating layer A and the resistance coating layer B, the edge effect is reduced, It is possible to obtain a developer having a high image density, a small amount of background stain, and hardly causing carrier adhesion.
[0024]
When the high-resistance coating layer A and the resistance coating layer B are provided, carrier adhesion due to charge induction (influence of a bias voltage and a development potential) due to the low-resistance of the small-sized carrier is prevented, Edge effects are prevented, image density is prevented from lowering, and background stains are prevented. This is because the inventors of the present invention have reported that carrier particles on which carrier adhesion has occurred using a carrier core material surface-treated with a silane coupling agent or the like (disclosed in JP-A-4-198946). It was obtained as a result of a detailed examination using a scanning electron microscope and fluorescent X-rays.
[0025]
That is, despite the surface treatment with a silane coupling agent or the like, the carrier particles adhering to the carrier have poor uniformity of the coating film as compared with the average carrier particles, and a part of the core material is The present inventors have discovered that many are exposed. If the carrier film becomes non-uniform and there is a portion with a small film thickness, or if a part of the carrier core material is exposed, the resistance of the carrier film becomes low, reflecting the low resistance of the carrier core material. In the case of a carrier having a small particle diameter, an uneven portion is present in the coating film, and when the resistance is reduced, carrier adhesion due to charge induction (influence of a bias voltage and a development potential) becomes severe.
[0026]
Based on the above findings, the present inventors previously formed a uniform high-resistance coating layer A on the surface of the carrier core material to substantially eliminate the exposed portion of the core material, and further provided a coating layer on top of the coating layer A. When a coating layer B having a lower resistance than that of A was formed, it was possible to obtain a developer having a small edge effect, a high image density, a small amount of background stain, and hardly causing carrier adhesion.
[0027]
The logarithm of the resistance value of the high resistance coating layer A (LogR _A ) Is preferably 15.5 Ωcm or more (DC resistance of 500 V), and is preferably provided so that the carrier core material is not substantially exposed. The uniformity of the coating layer A can be confirmed by X-ray fluorescence. The logarithm of the resistance value of the coating layer A (LogR _A ) Is less than 15.5 Ωcm, the carrier adhesion tends to increase due to the influence of the resistance of the carrier core material.
[0028]
The logarithm of the resistance value of the resistance coating layer B (LogR _B ) Is lower than the coating layer A, and the logarithm (LogR) of the resistance value of the coating layer in which the resistance coating layer B is laminated on the high resistance coating layer A is 10.0 Ωcm to 15.0 Ωcm (DC resistance of 500 V). Is preferred. When the resistance value is within the above range, a carrier with good carrier adhesion, a small edge effect, a high image density, a small background stain, and a good highlight granularity can be obtained. When the resistance value of the coating layer B is lower than 10.0 Ωcm, the edge effect is small and a high image density is obtained, but the carrier adhesion increases. If it is higher than 15.0 Ωcm, carrier adhesion is not a problem, but the edge effect is strong, the image density is low, and the graininess of highlight is also poor.
[0029]
In order to improve the edge effect and highlight graininess and obtain a high image density, the logarithm (LogR) of the resistance value of the entire coating layer in which the resistance coating layer B is laminated on the high resistance coating layer A is 12 More preferably, the resistance is in the range of 0.0 Ωcm to 14.0 Ωcm (DC resistance of 500 V).
[0030]
The resistance value in the present specification can be measured by the following method.
As shown in FIG. 2, a carrier 13 is filled in a cell 11 made of a fluororesin container containing electrodes 12a and 12b having a distance between electrodes of 2 mm and a surface area of 2 × 4 cm, and a DC voltage of 500 V is applied between both electrodes. The DC resistance is measured with a high resistance meter 4329A (4329A + LJK5HVLVWDQFH0HWHU; manufactured by Yokogawa Hewlett-Packard Co., Ltd.), and the logarithm LogR (Ωcm) of the electrical resistivity is calculated.
[0031]
Preferred carrier core materials used in the present invention include magnetic substances such as ferrite particles, magnetite particles, and iron powder particles. Further, the magnetic powder can be configured as a so-called resin dispersion carrier having a form in which a magnetic powder is dispersed in a known resin such as a phenol resin, an acrylic resin, or a polyester resin.
[0032]
However, the carrier core material used in the present invention is not limited to these. As described above, as long as the magnetic moment at 1 KOe is 40 emu / g or more, various conventionally known magnetic materials can be used. Can be used.
[0033]
When the carrier core material used in the present invention is ferrite particles, a large magnetic moment is generated even in a place where the magnetic field is small, such as at the exit of the developing region, so that carrier adhesion can be effectively prevented.
[0034]
Examples of the ferrite particles include magnetic particles such as Li-based ferrite, Mn-Zn-based ferrite, Mn-Mg-based ferrite, Cu-Zn-based ferrite, Ni-Zn-based ferrite, Ba-based ferrite, and Mn-based ferrite. This is a sintered body represented by the following formula (1).
[0035]
Embedded image
(MO) _x (NO) _y (Fe ₂ O ₃ ) _Z (1)
However, x + y + z = 100 mol%, M and N are metal atoms in Ni, Cu, Zn, Li, Mg, Mn, Sr, Ca, etc., respectively, and are a divalent metal oxide and a trivalent iron oxide. It is composed of a complete mixture with the product.
[0036]
When the carrier core material used in the present invention is magnetite particles, a large magnetic moment is generated even in a place where the magnetic field is small, such as at the exit of the developing region, which is effective for preventing carrier adhesion.
[0037]
Magnetite particles are FeO.Fe ₂ O ₃ Which has a magnetic moment at 1 KOe of 60 to 90 emu / g. Although the magnetite particles have a lower resistance than the ferrite particles, the carrier adhesion is effectively prevented by providing the high resistance coating layer A on the carrier core material surface.
[0038]
When the carrier core material used in the present invention is iron powder particles, the magnetic moment of 1 KOe is about 90 emu / g, and the true specific gravity is about 1.5 times that of ferrite particles. The magnetic moment per unit is about 1.5 times that of the ferrite particles, the magnetic binding force from the developing sleeve is large, and the carrier adhesion can be prevented by looking only at the magnetic characteristics. However, the iron powder particles have low resistance even if the surface is partially oxidized, and break down at an applied voltage of 100 V or less. Therefore, the effect on carrier adhesion is exhibited only when the high-resistance coating layer A is formed on the surface of the iron powder particles.
[0039]
In the present invention, a magnetic material such as ferrite, magnetite, and iron particles are dispersed in resin particles, and the resin particles containing 80 to 90% by weight of a magnetic material spherical by a polymerization method, a spray drying method, or the like are used as a carrier core material. Can be used as Since the resin particles have a high magnetic substance content and a large number of magnetic substances on the particle surface, the resistance of the particles is low. Therefore, the effect of carrier adhesion is exhibited only when the high resistance coating layer A is formed on the surface of the resin particles.
[0040]
The resin particles containing the magnetic material have a high resistance when the amount of the magnetic material is reduced (for example, when the amount of the magnetic material is about 50% by weight), but the magnetic moment of 1 KOe is only about 30 emu / g. Moreover, since the true specific gravity is only about １ ／ that of a normal magnetic substance (for example, magnetite), the magnetic moment per particle is about ４ of that of magnetite particles, and the magnetic binding force on the developing sleeve becomes extremely small. Therefore, carrier adhesion increases.
[0041]
In the present invention, as the resin that can be used to form the high-resistance coating layer A and the low-resistance coating layer B that the carrier core material has on its surface, conventionally known various resins used in the production of carriers are used. Although it can be used, a silicone resin containing a repeating unit represented by the following formula (2) is preferably used.
[0042]
Embedded image

[0043]
In the above formula (1), R ¹ Represents a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, a lower alkyl group having 1 to 4 carbon atoms, or an aryl group (a phenyl group, a tolyl group, etc.); ² Represents an alkylene group having 1 to 4 carbon atoms or an arylene group (such as a phenylene group).
[0044]
The aryl group of the above formula (2) has 6 to 20, preferably 6 to 14 carbon atoms. The aryl group includes an aryl group derived from benzene (phenyl group), an aryl group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene, and anthracene; and a chain polycyclic aromatic compound such as biphenyl and terphenyl. And aryl groups derived from aromatic hydrocarbons.
Various substituents may be bonded to the aryl group.
[0045]
In the arylene group of the above formula (2), the carbon number is 6 to 20, preferably 6 to 14. The arylene group includes an arylene group derived from benzene (a phenylene group), an arylene group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene, and anthracene; and a chain polycyclic aromatic compound such as biphenyl and terphenyl. And arylene groups derived from aromatic hydrocarbons.
Various substituents may be bonded to the arylene group.
[0046]
In the present invention, a straight silicone resin can be used as the silicone resin. Examples of such a material include KR271, KR272, KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406 (manufactured by Dow Corning Toray Silicone Co., Ltd.) and the like.
[0047]
In the present invention, a modified silicone resin can be used as the silicone resin. Examples of such a material include epoxy-modified silicone, acrylic-modified silicone, phenol-modified silicone, urethane-modified silicone, polyester-modified silicone, and alkyd-modified silicone.
[0048]
Specific examples of the modified silicone resin include an epoxy-modified product: ES-1001N, an acrylic-modified silicone: KR-5208, a polyester-modified product: KR-5203, an alkyd-modified product: KR-206, and a urethane-modified product: KR-305 ( Above, Shin-Etsu Chemical Co., Ltd.), epoxy-modified product: SR2115, alkyd-modified product: SR2110 (manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.
[0049]
The silicone resin used in the present invention may contain an aminosilane coupling agent in an appropriate amount (0.001 to 30% by weight), and examples thereof include the following.
[0050]
Embedded image

[0051]
Further, in the present invention, as the resin constituting the high resistance coating layer A and the resistance coating layer B, the following resins may be used alone or in combination with the above silicone resin.
Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, Styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer Polymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, Styrene-phenyl methacrylate copolymer) Styrene resin such as styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, ketone resin, ethylene -Ethyl acrylate copolymer, xylene resin, polyamide resin, phenol resin, polycarbonate resin, melamine resin and the like.
[0052]
The resistivity of the high resistance coating layer A and the low resistance coating layer B can be adjusted by adding a conductive fine powder to the coating resin layer. Examples of the conductive fine powder include metal or metal oxide powder such as conductive ZnO and Al, and SnO prepared by various methods. ₂ Or SnO doped with various elements ₂ , TiB ₂ , ZnB ₂ , MoB ₂ And conductive polymers such as silicon carbide, polyacetylene, polyparaphenylene, poly (para-phenylene sulfide) polypyrrole, and polyethylene, and carbon blacks such as furnace black, acetylene black, and channel black.
[0053]
These conductive fine powders can be prepared by the following method, that is, after adding the conductive fine powder to a solvent used for coating or a resin solution for coating, a dispersing machine using a medium such as a ball mill or a bead mill, or a high-speed rotating blade Can be uniformly dispersed by using a stirrer equipped with
[0054]
The resistivity of the high-resistance coating layer A or the low-resistance coating layer B can be adjusted by controlling the thickness of the coating layer A or the coating layer B coated on the carrier particles.
[0055]
The film thickness of the high resistance coating layer A is preferably formed to be 0.05 μm or more, more preferably 0.1 μm or more. In order to apply the coating layer A uniformly, it is desirable to dilute the coating resin, reduce the solid content of the resin in the solvent as much as possible, and apply the surface of the carrier core particles over time. .
[0056]
The thickness of the low resistance coating layer B is preferably formed at 0.02 to 1 μm, more preferably 0.03 to 0.8 μm.
[0057]
Since the thickness of the high-resistance coating layer A and the low-resistance coating layer B is extremely small, the weight average particle diameter Dw and the particle size distribution of the carrier composed of the carrier particles having these coating layers and the carrier core material composed of the core material particles Have substantially the same weight average particle size Dw and particle size distribution.
[0058]
In the present invention, a magnetic material or the like is pulverized, a carrier core material is prepared by classifying the pulverized material particles so as to obtain a predetermined particle size, and each particle of the carrier core material obtained by the classification is prepared. It is preferable to form the carrier by forming the high resistance coating layer A on the surface and forming the low resistance coating layer B thereon. Further, the carrier is obtained by pulverizing a magnetic material or the like to form crushed particles, forming the high-resistance coating layer A on the surface of the crushed particles, forming the low-resistance coating layer B thereon, and then classifying. Is also preferable.
[0059]
In the present invention, the high resistance coating layer A is formed by coating a carrier core material with a diluted resin, and the low resistance coating layer B is coated with the diluted resin on the coating layer A. It is preferable that it is formed. If such a method is performed using a fluidized bed type coating apparatus, the carrier of the present invention can be efficiently produced.
[0060]
Further, in the present invention, the high-resistance coating layer A has a coating ratio of the resin fine particles on the surface of the carrier core material of 70% or more by mixing resin fine particles prepared by emulsion polymerization or the like with a carrier core material. In this way, it is possible to form a film without using a solvent by mixing and adhering, and further heating or mechanically mixing or applying an impact force.
In this case, if the low resistance coating layer B may be formed by coating with the diluted resin as described above, a required amount of resin fine particles are mixed and adhered similarly to the resistance coating layer A, Further, it may be formed by heating, mechanical mixing, or applying impact force.
[0061]
When the resin fine particles are mixed and adhered to the surface of the carrier core material, if the coverage is less than 70%, the surface of the carrier core material may be exposed even in a state where the film is formed. The coverage is calculated by the following equation (2).
(Equation 2)

[0062]
The method for forming the high-resistance coating layer A and the high-resistance coating layer B on the particle surface of the carrier core material is not limited to the above-mentioned method, and a known method such as a spray drying method or an immersion method can be used.
[0063]
The classification includes wind classification, sieving classification (sieving), vibration sieving, and the like. In the present invention, it is preferable to use a vibration sieving machine with an ultrasonic oscillator. By classifying the pulverized carrier core material while applying ultrasonic vibration to the sieve (wire mesh) of the vibrating sieve, small meshes of the sieve (wire mesh) can be easily prevented from being clogged. However, classification can be performed efficiently.
[0064]
A carrier core material is prepared by classifying the pulverized product particles so as to obtain a predetermined particle size, and the high resistance coating layer A is formed on the surface of each particle of the carrier core material obtained by the classification, It is also preferable to form a carrier by classifying the resin-coated particles by forming a low-resistance coating layer B thereon. Also in the classification in this case, it is preferable to use the vibration sieve equipped with the ultrasonic oscillator.
[0065]
It is preferable that the ultrasonic vibration for vibrating the wire net is generated by supplying a high-frequency current to a converter including a PZT vibrator and converting it into ultrasonic vibration. Ultrasonic vibration generated by the converter is transmitted to a resonance member fixed to the wire mesh, and the resonance member resonates by the ultrasonic vibration, and vibrates the wire mesh to which the resonance member is fixed. The frequency at which the wire net is vibrated is preferably 20 to 50 kHz, more preferably 30 to 40 kHz. The shape of the resonance member may be any shape as long as it is suitable for vibrating the wire mesh, and is usually a ring shape. The vibration direction for vibrating the wire mesh is preferably a vertical direction.
[0066]
As described above, the vibration sieving machine with the ultrasonic oscillator used in the present invention preferably has a structure for transmitting the ultrasonic vibration to the wire mesh surface by the resonance ring.
FIG. 1 shows an example of a preferred structure of a vibration sieve with an ultrasonic oscillator. In FIG. 1, 1 is a vibrating sieve, 2 is a cylindrical container, 3 is a spring, 4 is a base (support), 5 is a wire mesh, 6 is a resonance ring, 7 is a high-frequency current cable, 8 is a converter, and 9 is a ring shape. Indicates a frame. To operate the vibrating sieve (circular sieve) with the ultrasonic oscillator shown in FIG. 1, a high-frequency current is supplied to the converter 8 via the cable 7. The high-frequency current supplied to the converter 8 is converted into an ultrasonic vibration. The ultrasonic vibration generated by the converter 8 causes the resonance ring 8 to which the converter 8 is fixed and the ring-shaped frame 9 connected thereto to vibrate in the vertical direction. The vibration of the resonance ring 6 causes the resonance ring 6 and the wire mesh 5 fixed to the frame 9 to vibrate in the vertical direction. A vibration sieving machine with an ultrasonic oscillator is sold, for example, available from Koei Sangyo Co., Ltd. under the product name "Ultrasonic".
[0067]
The developer of the present invention comprises a toner comprising toner particles containing at least a binder resin and a colorant, and a small particle size carrier having a specific range of particle size distribution, a specific range of resistance, and a specific range of magnetic characteristics described above. And at least are mixed. The weight average particle diameter Dt of the toner particles used in the present invention is 8 μm or less, and preferably 6 μm or less. If the weight average particle size of the toner particles exceeds 8 μm, there is a possibility that a developer having particularly good graininess and background stain cannot be obtained.
The weight average particle diameter Dt of the toner particles in the present specification can be measured using a Coulter counter or the like.
[0068]
The toner particles used in the present invention contain a colorant, fine particles, a charge control agent, a release agent, and the like in a binder resin containing a thermoplastic resin as a main component. As long as the toner has a weight average particle size, an amorphous or spherical toner produced by various production methods such as a polymerization method and a granulation method can be used. Further, both magnetic toner and non-magnetic toner can be used.
[0069]
The binder resin (binder) constituting the toner used in the present invention is not particularly limited, but those described below are preferably used alone or in combination.
[0070]
Styrene-based resins include homopolymers of styrene such as polystyrene and polyvinyltoluene and substituted products thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-acrylic acid Methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer Polymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene- Isoprene copolymer, styrene-maleic acid Polymers, styrene-based copolymers such as styrene-maleic acid ester copolymers; examples of acrylic binders include polymethyl methacrylate and polybutyl methacrylate, and others, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, Polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. Can be
[0071]
Further, the polyester resin can further lower the melt viscosity while securing the stability during storage of the toner, as compared with a styrene or acrylic resin. Such a polyester resin can be obtained, for example, by a polycondensation reaction between an alcohol and a carboxylic acid.
[0072]
Examples of the alcohol include diols such as polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, and 1,4-butenediol; Etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene bisphenol A, which are saturated or unsaturated with 3 to 22 carbon atoms Dihydric alcohol units substituted with saturated hydrocarbon groups, other dihydric alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaethritol dipentane D Litol, tripentaethritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Higher trivalent or higher alcohol monomers such as methylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene are exemplified.
[0073]
Examples of the carboxylic acid used to obtain the polyester resin include palmitic acid, stearic acid, monocarboxylic acids such as oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, and succinic acid. , Adipic acid, sebacic acid, malonic acid, divalent organic acid monomers obtained by substituting these with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters and linolein Dimer from acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2 1,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl Trivalent or higher polyvalent carboxylic acid monomers such as 2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid embol trimer acid, and anhydrides of these acids Is mentioned.
[0074]
Examples of the epoxy resin include a polycondensate of bisphenol A and epochlorohydrin. For example, Epomic R362, R364, R365, R366, R367, R369 (all manufactured by Mitsui Petrochemical Industries, Ltd.), Epototo YD -011, YD-012, YD-014, YD-904, YD-017, commercially available products such as Epocoat 1002, 1004, 1007 (all manufactured by Tohto Kasei Co., Ltd.) (all manufactured by Shell Chemical Company) Is mentioned.
[0075]
Colorants constituting the toner used in the present invention include carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, Hansa Yellow G, rhodamine 6G, lake, calco oil blue, chrome yellow, and quinacridone. Any conventionally known dyes and pigments such as, for example, benzidine yellow, rose bengal, triallylmethane dyes, monoazo dyes, disazo dyes and pigments can be used alone or in combination.
[0076]
In the present invention, a magnetic material can be obtained by adding a magnetic material to the toner. As the magnetic material, a fine powder such as a ferromagnetic material such as iron or cobalt, magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Cu-Zn-based ferrite, Ni-Zn ferrite, or Ba ferrite can be used.
[0077]
In the toner used in the present invention, for the purpose of sufficiently controlling the triboelectric charging property of the toner, a so-called charge control agent, for example, a metal complex salt of a monoazo dye, nitrohumic acid and its salts, salicylic acid, a naphthoic salt, a dicarboxylic acid Co, An amino compound such as a metal complex such as Cr or Fe, a quaternary ammonium compound, or an organic dye can be contained.
[0078]
Further, a release agent may be added to the toner used in the present invention as needed.
As the release agent, low molecular weight polypropylene, low molecular weight polyethylene, carnauba wax, microcrystalline wax, jojoba wax, rice wax, montanic acid wax and the like can be used alone or in combination, but are not limited thereto. Not something.
[0079]
Additives can be added to the toner used in the present invention. In order to obtain a good image, it is important to impart sufficient fluidity to the toner. For this purpose, it is generally effective to externally add fine particles of a hydrophobic metal oxide or a fine particle such as a lubricant as a fluidity improving material, and use a metal oxide, an organic resin fine particle, a metal soap or the like as an additive. It can be used. Specific examples of these additives include lubricants such as Teflon (R) and zinc stearate, and abrasives such as cerium oxide and silicon carbide; ₂ , TiO ₂ And fluidity-imparting agents such as inorganic oxides; those known as anti-caking agents, and their surface-treated products. In order to improve the fluidity of the toner, hydrophobic silica is particularly preferably used.
[0080]
In the developer of the present invention, the coverage of the toner with respect to the carrier is preferably 25% to 95%, and more preferably 30% to 90%. When the toner coverage is 25% or less, the image density tends to decrease. On the other hand, when the content is 95% or more, the background dirt increases, and the granularity is slightly deteriorated.
[0081]
The coverage of the toner with respect to the carrier is calculated by the following equation (3).
[Equation 3]
Coverage (%) = (Wt / Wc) × (ρc / ρt) × (Dc / Dt) × (1/4) × 100 (3)
In the formula (3), Dc is the weight average particle diameter of the carrier (μm), Dt is the weight average particle diameter of the toner (μm), Wt is the weight of the toner (g), Wc is the weight of the carrier (g), and ρt is True toner density (g / cm ³ ), Ρc is the true carrier density (g / cm) ³ ) Respectively. The true specific gravity of the toner is 1.25 g / cm ³ And
[0082]
In the developer of the present invention, it is preferable that the toner charge amount is 10 to 35 μc / g when the toner coverage on the carrier is 50%. When such a developer is used, it is possible to obtain a developer having good carrier adhesion, edge effect, image density, granularity, and background contamination. When the charge amount is 10 μc / g or less, background contamination tends to increase, and when the charge amount is 35 μc / g or more, the image density tends to decrease and the edge effect also increases.
[0083]
The developing method of the present invention is a method of developing a latent image using the above-described developer of the present invention. In this method, when an AC voltage obtained by superimposing an AC voltage on a DC voltage is applied as a developing bias applied from the outside, a sufficient image density can be obtained. In particular, the graininess of highlights is improved. Further, when only a DC voltage is applied as a developing bias, carrier adhesion and an edge effect are significantly improved, and a margin for background contamination is increased. In addition, it is possible to lower the developing bias, and it is possible to increase the image density.
[0084]
The developer container for electrophotography of the present invention contains the above-described developer of the present invention. In this case, various conventionally known containers can be used.
[0085]
The image forming apparatus of the present invention uses the above-described developing container of the present invention as its developing container. As the image forming apparatus in this case, various conventionally known apparatuses can be used.
[0086]
【Example】
Hereinafter, the present invention will be described in detail based on examples. However, these examples do not limit the present invention at all. In the following, "parts" indicates parts by weight.
First, toners I and II used in Examples and Comparative Examples were prepared.
[0087]
Toner I
100 parts of a polyester resin, 3.5 parts of a quinacridone magenta pigment, and 4 parts of a fluorinated quaternary ammonium salt are sufficiently mixed in a blender, and then melt-kneaded by a twin-screw extruder, extruded, and cooled. After that, the mixture is coarsely pulverized by a cutter mill, finely pulverized by a jet air-flow type fine pulverizer, and further classified by an air classifier to obtain a weight average average particle size Dt of 7.6 μm (shown in Table 2) and a true specific gravity of 1. .25 g / cm ³ Was obtained. Further, 0.8 part of hydrophobic silica fine particles (R972: manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts of the toner base particles, and mixed with a Henschel mixer to obtain Toner I.
[0088]
Toner II
A mother toner having a weight average particle size Dt of 5.8 μm (shown in Table 2) and a true specific gravity of 1.25 g / cm was prepared in the same manner as in the toner I, and the hydrophobic silica fine particles (R972) 1.0 were added thereto. Parts were added and mixed with a Henschel mixer to obtain Toner II.
[0089]
Example 1
A silicone resin (SR2411, manufactured by Toray Dow Corning Silicone Co., Ltd.) was diluted to prepare a silicone resin solution (solid content: 2.5%).
Next, using a fluidized bed type coating apparatus, the above silicone resin was coated on the surface of each 5 kg of carrier core material particles 1 (CuZn ferrite, magnetic moment of 43 KOe / 43 emu / g) having the properties shown in Table 1. The solution was applied at a rate of about 20 g / min in an atmosphere of 90 ° C., a small amount of the carrier in this state was sampled, and the carrier was further heated at 240 ° C. for 2 hours. When the film thickness was measured by X-ray fluorescence, a high-resistance coating layer A made of a 0.1 μm silicone resin was formed.
[0090]
Further, 7 parts of carbon, aminosilane coupling agent, H ₂ NCH ₂ CH ₂ NHCH ₂ Si (OCH ₃ ) ₃ Was added to form a coating layer having a total film thickness of 0.58 μm of the high-resistance coating layer A and the low-resistance coating layer B, and a carrier A was obtained.
The resistance of the coating layer A is LogR _A = 16.1 Ωcm, and the resistance of the coating layer obtained by laminating the coating layer B on the coating layer A was LogR = 10.5 Ωcm.
The weight average particle diameter Dw of the carrier core material 1, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), and the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier A _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0091]
A developer was manufactured using the toner I and the carrier A.
An image is formed using the obtained developer, and the granularity of highlight, carrier adhesion, edge effect, image density, background stain, background stain after 20K run are tested, and the image quality is confirmed. The sex was examined. Table 2 shows the results.
[0092]
[Table 1]

[0093]
[Table 2]

[0094]
Images were prepared using Imagio Color 5000 (a digital color copier / printer multifunction printer manufactured by Ricoh) under the following developing conditions.
・ Development gap (photoconductor-development sleeve): 0.40 mm
-Doctor gap (developing sleeve-doctor): 0.70 mm
・ Photoconductor linear velocity 245mm / sec
· (Developing sleeve linear velocity / photoconductor linear velocity) = 1.50
Write density: 600 dpi
-Charging potential (Vd): -700V
A potential (V /) after exposure of a portion corresponding to an image portion (solid document): -100 V
・ Developing bias: DC-500V / AC bias component: 2KHZ, -200V to -1000V, 50% duty
[0095]
Quality evaluation for highlight graininess, edge effect, image density, and background stain was performed on transfer paper according to the following criteria, and quality evaluation for carrier adhesion was performed on the photoreceptor after development and before transfer according to the following criteria. In addition, background soil after 20K run was evaluated according to the following criteria, and reliability was evaluated.
[0096]
(1) Granularity of highlight:
Rank samples were prepared and evaluated on a 10-point scale. Rank 10 is best.
[0097]
(2) Carrier adhesion:
When the carrier adheres, it causes damage to the photosensitive drum and the fixing roller, and lowers the image quality. Even if the carrier adhered, only a part of the carrier was transferred to the paper. Therefore, the carrier adhesion was directly observed on the photosensitive drum and evaluated. Further, since the manner in which carrier adhesion occurs differs depending on the image pattern, the following method was used to evaluate the difficulty of carrier adhesion.
The charging potential (Vd) is fixed at -700 V, and the developing bias (Vb) is fixed at DC-400 V, and the background (⇒ unexposed portion) is developed, and 30 cm on the photoreceptor is developed. ² The number of carriers adhered to the sample was directly counted to evaluate the carrier adhesion. The smaller the number, the more difficult the carrier adhesion.
The background potential at this time is 300 V from the value of Vb-Vd.
In addition, when the developing AC bias was applied, a DC bias Vb = 300 V and ± 400 V were superimposed (frequency 2 KHZ, 50% duty).
[0098]
(3) Edge effect
The charging potential was fixed at -700 V, the bias potential was fixed at -550 V, the solid portion potential was fixed at -100 V, and the potential of the intermediate density was set at Vm. The potential in the intermediate density region was changed by modulating the laser power, and the potential at which no white spots occurred at the boundary between the solid image portion and the boundary of the intermediate density region was measured. As the absolute value of Vm is larger, the edge effect is less likely to occur in the developer.
In addition, under the condition of the application of the AC bias, the DC bias was applied with a superposition of ± 400 V (frequency 2 KHZ, 50% duty).
[Table 3]

[0099]
(4) Image density:
The center of the solid portion of 30 mm × 30 mm under the above-mentioned developing conditions was measured at five places with an X-Rite 938 spectrocolorimeter, and the average value was defined as the image density.
[0100]
(5) Background dirt:
Under the above development conditions, the background stain on the background was evaluated on a 10-point scale.
The higher the rank, the less the background dirt, and the rank 10 is the best.
[0101]
(6) Dirt after 20K run
While replenishing the magenta toner A or toner B used for initial image output, running evaluation was performed on 20,000 sheets using a character image chart with an image area ratio of 6%. Under the above development conditions, the background stain on the background was evaluated on a 10-point scale. The higher the rank, the less the background soiling, and the rank 10 is the best.
[0102]
Example 2
Except that the amount of carbon in the low resistance coating layer B was 3.8 parts, the total film thickness of the coating layer A and the coating layer B was 0.57 μm and the carrier resistance LogR was 14. A carrier B of 6 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 1, the content ratio (% by weight) of particles having a particle size of 44 μm or less, the content ratio (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier B _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0103]
A developer was manufactured using the toner I and the carrier B.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0104]
Example 3
Except that the amount of carbon in the low-resistance coating layer B was 5.0 parts and the amount of the aminosilane coupling agent was 2.5 parts, the total amount of the coating layer A and the coating layer B was calculated in exactly the same manner as in Example 1. A carrier C having a thickness of 0.57 μm and a carrier resistance LogR of 13.1 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 1, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier C _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0105]
A developer was manufactured using the toner I and the carrier C.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0106]
Example 4
Instead of the carrier core material 1, a carrier core material 2 having a content of particles of 22 μm or less of 0.3% by weight was used, and the carbon amount of the low-resistance coating layer B was 5.0 parts, and aminosilane cup was used. Except that the amount of the ring agent was set to 2.5 parts, a carrier D having a total thickness of the coating layer A and the coating layer B of 0.57 μm and a carrier resistance LogR of 13.1 Ωcm was obtained in the same manner as in Example 1. Obtained.
The weight average particle diameter Dw of the carrier core material 2, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment (emu) at 1 KOe of the carrier core material 2 / G), LogR of carrier D _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0107]
A developer was manufactured using the toner I and the carrier D.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0108]
Comparative Example 1
Except that the high-resistance coating layer A was not formed, and only the low-resistance coating layer B was formed to have the same thickness as the total film thickness of the first embodiment, the coating layer was formed in the same manner as in the first embodiment. A carrier E having a B film thickness of 0.58 μm and a carrier resistance LogR of 10.5 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 1, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier E, amount of carbon (parts), amount of aminosilane coupling agent (parts), and film thickness (μm) of coating layer B are shown in Table 1.
[0109]
A developer was manufactured using the toner I and the carrier E.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0110]
Comparative Example 2
Except for using the core material 3 having a content of particles of 44 μm or less of 69%, the total film thickness of the coating layer A and the coating layer B was 0.58 μm, A carrier F having a resistance LogR of 10.6 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 3, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), and the magnetic moment (emu) at 1 KOe of the carrier core material 3 / G), LogR of carrier F _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0111]
A developer was manufactured using the toner I and the carrier F.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0112]
Comparative Example 3
Except for using the carrier core material 4 having a content of particles of 22 μm or less of 6.7%, the total film thickness of the coating layer A and the coating layer B is set to 0. A carrier G having a carrier resistance LogR of 10.4 Ωcm was obtained at 57 μm.
The weight average particle diameter Dw of the carrier core 4, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 4. / G), LogR of carrier G _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0113]
A developer was manufactured using the toner I and the carrier G.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0114]
Comparative Example 4
A carrier H was produced in exactly the same manner as in Example 1, except that the carrier core material 5 having a magnetic moment of 35 emu / g was used. In exactly the same manner as in Example 1, a carrier H having a total film thickness of the coating layer A and the coating layer B of 0.57 μm and a carrier resistance LogR of 10.5 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 5, the content ratio (% by weight) of particles having a particle size of 44 μm or less, the content ratio (% by weight) of particles having a particle size of 22 μm or less, the magnetic moment (emu) at 1 KOe of the carrier core material 5 / G), LogR of carrier H _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0115]
A developer was manufactured using the toner I and the carrier H.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0116]
Comparative Example 5
Except that the high-resistance coating layer A was not formed, a carrier I having a total thickness of the coating layer B of 0.58 μm and a carrier resistance LogR of 14.7 Ωcm was obtained in the same manner as in Example 2.
The weight average particle diameter Dw of the carrier core material 1, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier I _A , LogR, the amount of carbon (parts), the amount of the aminosilane coupling agent (parts), and the thickness (μm) of the coating layer B are shown in Table 1.
[0117]
A developer was manufactured using the toner I and the carrier I.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0118]
Example 5
Except that the amount of carbon in the low resistance coating layer B was 8.5 parts and the amount of the aminosilane coupling agent was 5.0 parts, the total film of the coating layer A and the coating layer B was produced in the same manner as in Example 1. A carrier J having a thickness of 0.59 μm and a carrier resistance LogR of 9.4 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 1, the content ratio (% by weight) of particles having a particle size of 44 μm or less, the content ratio (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier B _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0119]
A developer was manufactured using the toner I and the carrier J.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0120]
Example 6
Except that the amount of carbon in the low-resistance coating layer B was reduced to 2.5 parts and the amount of the aminosilane coupling agent was changed to 2.0 parts, the coating layers A and B were formed in exactly the same manner as in Example 1. A carrier K having a total thickness of 0.59 μm and a carrier resistance LogR of 15.4 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 1, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment (emu) at 1 KOe of the carrier core material 1 / G), LogR of carrier K _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0121]
A developer was manufactured using the toner I and the carrier K.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0122]
Example 7
Except that the carrier core material 6 having a magnetic moment of 63 emu / g was used, the total thickness of the coating layer A and the coating layer B was 0.57 μm, and the carrier resistance LogR was 13. A carrier L of 2 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core 6, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 6. / G), LogR of carrier L _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0123]
A developer was manufactured using the toner I and the carrier L.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0124]
Example 8
Except that the content of the aminosilane coupling agent was changed from 2.5 parts to 4 parts, the toner charge amount when the 7.6 μm toner was 50% coated was 40 μc / g in the same manner as in Example 7. A carrier M having a total thickness of the coating layer A and the coating layer B of 0.56 μm and a carrier resistance LogR of 13.2 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core 6, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 6. / G), LogR of carrier M _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0125]
A developer was manufactured using the toner I and the carrier L.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0126]
Example 9
Except that the content of the aminosilane coupling agent was changed from 2.5 parts to 1 part, the charge amount of the toner when the 7.6 μm toner was 50% coated was 8 μc / g. A carrier N having a total thickness of the coating layer A and the coating layer B of 0.58 μm and a carrier resistance LogR of 13.2 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core 6, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 6. / G), LogR of carrier N _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0127]
A developer was manufactured using the toner I and the carrier L.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0128]
Example 10
Using the carrier L obtained in Example 7, the developer was adjusted so that the coverage of the 7.6 μm toner was 20%.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0129]
Example 11
Using the carrier L obtained in Example 7, the developer was adjusted so that the coverage of the 7.6 μm toner became 100%.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0130]
Example 12
Except that the carrier core material 7 having a magnetic moment of 78 emu / g was used, the total thickness of the coating layer A and the coating layer B was 0.59 μm, and the carrier resistance LogR was 10.5 Ωcm, exactly as in Example 1. Was obtained.
The weight average particle diameter Dw of the carrier core 7, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 7. / G), LogR of carrier Q _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0131]
A developer was manufactured using the toner I and the carrier Q.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0132]
Example 13
To the carrier core material 1, polymethyl methacrylate resin fine particles (MP1450, 0.25 μm, manufactured by Soken Chemical Co., Ltd.) are dry-mixed so as to have a coverage of 80%, and heat and mechanical impact force are further applied. To form a film on the surface of the carrier core material 1 to form a high resistance coating layer A. A low-resistance coating layer B was formed thereon in exactly the same manner as in Example 1, and a carrier R having a total thickness of the coating layer A and the coating layer B of 0.58 μm and a carrier resistance LogR of 10.5 Ωcm was obtained.
[0133]
A developer was manufactured using the toner I and the carrier R.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0134]
Example 14
Using a carrier core material 8 made of magnetite having the characteristics shown in Table 1, the total thickness of the coating layer A and the coating layer B was 0.58 μm, and the carrier resistance LogR was 13 in the same manner as in Example 8. A carrier S of 0.2 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core 8, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 8. / G), LogR of carrier S _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0135]
A developer was manufactured using the toner I and the carrier S.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0136]
Comparative Example 6
Except that the high-resistance coating layer A was not formed, a carrier T having a coating layer B thickness of 0.58 μm and a carrier resistance LogR of 13.2 Ωcm was obtained in exactly the same manner as in Example 14.
The weight average particle diameter Dw of the carrier core 8, the content (% by weight) of particles having a particle size of 44 μm or less, the content (% by weight) of particles having a particle size of 22 μm or less, and the magnetic moment (emu) at 1 KOe of the carrier core 8. / G), LogR of carrier T, amount of carbon (parts), amount of aminosilane coupling agent (parts), and total film thickness (μm) of coating layers A and B are shown in Table 1.
[0137]
A developer was manufactured using the toner I and the carrier T.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0138]
Example 15
Using a carrier core material 9 made of an iron powder core material having the characteristics shown in Table 1, in the same manner as in Example 8, the total film thickness of the coating layer A and the coating layer B was 0.57 μm, and the carrier resistance was A carrier U having a LogR of 13.3 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 9, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), and the magnetic moment (emu) at 1 KOe of the carrier core material 9 / G), LogR of carrier U _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0139]
A developer was manufactured using the toner I and the carrier U.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0140]
Comparative Example 7
Except that the high-resistance coating layer A was not formed, a carrier V having a coating layer B thickness of 0.57 μm and a carrier resistance LogR of 13.3 Ωcm was obtained in exactly the same manner as in Example 15.
The weight average particle diameter Dw of the carrier core material 9, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), and the magnetic moment (emu) at 1 KOe of the carrier core material 9 / G), LogR of carrier V, amount of carbon (parts), amount of aminosilane coupling agent (parts), and thickness (μm) of coating layer B are shown in Table 1.
[0141]
A developer was manufactured using the toner I and the carrier V.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0142]
Example 16
The same as Example 8 except that a carrier core material 10 made of a resin in which magnetite particles were dispersed and having a magnetic moment of 55 emu / g was used, and the amount of carbon in the low-resistance coating layer B was 4.0 parts. By the method, a carrier W having a total thickness of the coating layer A and the coating layer B of 0.59 μm and a carrier resistance LogR of 13.3 Ωcm was obtained.
The weight average particle diameter Dw of the carrier core material 10, the content ratio (% by weight) of particles having a particle size of 44 μm or less, the content ratio (% by weight) of particles having a particle size of 22 μm or less, the magnetic moment (emu) at 1 KOe of the carrier core material 10 / G), LogR of carrier W _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0143]
A developer was manufactured using the toner I and the carrier W.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0144]
Comparative Example 8
Except that the high-resistance coating layer A was not formed, a carrier X having a coating layer B thickness of 0.59 μm and a carrier resistance LogR of 13.3 Ωcm was obtained in exactly the same manner as in Example 16.
The weight average particle diameter Dw of the carrier core material, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), the magnetic moment at 1 KOe of the carrier core material (emu / g) ), The LogR of the carrier X, the amount of carbon (parts), the amount of the aminosilane coupling agent (parts), and the thickness (μm) of the coating layer B are shown in Table 1.
[0145]
A developer was manufactured using the toner I and the carrier X.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0146]
Example 17
The toner II (5.8 micron toner) was mixed and stirred with the carrier A obtained in Example 1 to prepare a developer.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0147]
Example 18
The carrier core material 4 having a content of particles of 22 μm or less of 6.7% is classified by a vibrating sieve equipped with an ultrasonic vibrator to reduce the content of particles of 22 μm or less to 2.8%. Using the carrier core material 11 thus obtained, a carrier Y was obtained in exactly the same manner as in Example 1.
The weight average particle diameter Dw of the carrier core material 11, the content ratio (% by weight) of particles having a particle size of 44 μm or less, the content ratio (% by weight) of particles having a particle size of 22 μm or less, the magnetic moment (emu) at 1 KOe of the carrier core material 11 / G), LogR of carrier Y _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0148]
A developer was manufactured using the toner I and the carrier Y.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0149]
Example 19
The carrier core material 11 obtained in Example 18 was further classified by using an ultrasonic vibration sieve provided with a resonance ring, and the carrier core material 12 in which the content ratio of particles of 22 μm or less was reduced to 0.2% was obtained. Produced. Using this, a carrier Z was obtained in the same manner as in Example 1.
The weight average particle diameter Dw of the carrier core material 12, the content ratio of particles having a particle size of 44 μm or less (% by weight), the content ratio of particles having a particle size of 22 μm or less (% by weight), and the magnetic moment (emu) at 1 KOe of the carrier core material 12 / G), LogR of carrier Z _A , LogR, the amount of carbon (parts), the amount of aminosilane coupling agent (parts), and the total thickness (μm) of the coating layers A and B are shown in Table 1.
[0150]
A developer was manufactured using the toner I and the carrier Z.
An image was formed using the obtained developer, and quality evaluation and reliability evaluation were performed in the same manner as in Example 1. Table 2 shows the results.
[0151]
Example 20
Using the developer obtained in Example 1 by using the toner I and the carrier A, changing the applied bias (the AC bias is superimposed on the DC bias) to the DC bias, image formation is performed. Quality evaluation and reliability evaluation were performed. Table 2 shows the results.
[0152]
【The invention's effect】
Providing the developer for electrophotographic development of the present invention provides good dot reproducibility, good granularity in highlights, little edge effect, high image density, and high image quality with little background smear. In addition, carrier adhesion hardly occurs.
[Brief description of the drawings]
FIG. 1 is an explanatory structural view of a vibration sifter equipped with an ultrasonic oscillator.
FIG. 2 is a perspective view of a resistance measuring cell used for measuring the electrical resistivity of the carrier.
[Explanation of symbols]
1 vibrating sieve
2 cylindrical container
3 Spring
4 Base
5 Wire mesh
6 Resonance ring
7 Cable
8 Converter (vibrator)
9 Ring frame
11 cells
12 electrodes
13 career

Claims (22)

In an electrophotographic developer obtained by mixing at least toner particles having a weight average particle diameter Dt of at least 8 μm or less containing a binder resin and a colorant, and a carrier, the weight average particle diameter of a carrier core material constituting the carrier Dw is 20 to 45 μm, the content of particles having a particle size of 44 μm or less in the carrier core material is 80% by weight or more, and the content of particles having a particle size of 22 μm or less is 5.0% by weight or less, Further, the magnetic moment at 1 KOe of the carrier core material is 40 emu / g or more, and a high resistance coating layer A is formed on the surface of the carrier core material, and the resistance is higher than the high resistance coating layer A on the high resistance coating layer A. A low-resistance coating layer B having a low resistance is formed. The logarithm of the resistance value (LogR _A ) of the high-resistance coating layer A is 15.5 Ωcm or more (DC resistance of 500 V), and the entire coating layer in which the resistance coating layer B is formed on the high-resistance coating layer A 2. The developer according to claim 1, wherein the logarithm of the resistance value (LogR) is 10.0 Ωcm to 15.0 Ωcm (DC resistance of 500 V). The logarithm of the resistance value (LogR _A ) of the high-resistance coating layer A is 15.5 Ωcm or more (DC resistance of 500 V), and the entire coating layer in which the resistance coating layer B is formed on the high-resistance coating layer A The electrophotographic developer according to claim 1, wherein a logarithm of the resistance value (LogR) is 12.0 Ωcm to 14.00 Ωcm (DC resistance of 500 V). The electrophotographic developer according to any one of claims 1 to 3, wherein the content of particles having a particle size of 22 µm or less in the carrier core material is 1% by weight or less. 5. The developer according to claim 1, wherein the carrier core material has a magnetic moment at 1 KOe of 60 emu / g or more. The electrophotographic developer according to any one of claims 1 to 4, wherein the carrier core material has a magnetic moment at 1 KOe of 76 emu / g or more. The electrophotographic developer according to any one of claims 1 to 6, wherein the charge amount of the toner when the toner coverage on the carrier is 50% is 10 to 35 µc / g. The electrophotographic developer according to any one of claims 1 to 7, wherein the toner coverage is 25 to 95%. The high resistance coating layer A is formed by coating a carrier core material with a resin, and the low resistance coating layer B is formed by coating the coating layer A with a resin. An electrophotographic developer according to claim 1. The high resistance coating layer A is formed by mixing and adhering resin fine particles on the surface of the carrier core material so as to have a coverage of 70% or more, and further heating or mechanically mixing or applying an impact force. The developer for electrophotographic development according to any one of claims 1 to 9, wherein The developer according to any one of claims 1 to 10, wherein the carrier core material is ferrite particles. The developer according to claim 1, wherein the carrier core material is magnetite particles. The developer according to any one of claims 1 to 10, wherein the carrier core material is iron powder particles. The developer for electrophotographic development according to any one of claims 1 to 10, wherein the carrier core material is a resin particle containing a magnetic substance. 15. The developer according to claim 1, wherein a weight average particle diameter of the toner particles is 6.0 μm or less. An electrophotographic development method using the developer for electrophotography development according to claim 1. 17. The electrophotographic developing method according to claim 16, wherein a DC voltage is used as a developing bias. An electrophotographic developer, comprising: using a vibrating sieve equipped with an ultrasonic oscillator for classifying a carrier core material or a pulverized product particle used in the electrophotographic developer according to any one of claims 1 to 15. Method for producing carrier for agent. An electrophotographic developer carrier characterized by using a vibration sieving machine with an ultrasonic oscillator for classifying a resin-coated carrier used for the electrophotographic developer according to any one of claims 1 to 15. Production method. 20. The electrophotographic developer according to claim 18, wherein the vibration sieving machine with the ultrasonic oscillator has a structure for transmitting ultrasonic vibrations to a wire mesh surface by a resonance ring provided on the sieving machine. Carrier manufacturing method. A developer container for electrophotographic development, wherein the developer for electrophotography development according to claim 1 is stored. An image forming apparatus comprising the electrophotographic developer container according to claim 21.

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