JP3744971B2 - Two-component developer and image forming method - Google Patents

Description

から算出される比表面積Ｓ₂との比（Ｓ₁／Ｓ₂）が、好ましくは１．２〜２．０、より好ましくは１．３〜１．８、さらに好ましくは１．４〜１．７であることも一つの特徴である。
【００６５】
Ｓ₁／Ｓ₂が１．２より小さいと、キャリアの表面が平滑になってしまうことでキャリア芯材への樹脂の密着性が低下し、結果としてトナー飛散やカブリ，画像ムラが発生してしまう。Ｓ₁／Ｓ₂が２．０より大きいと、キャリア表面の凹凸が大きくなり過ぎ、磁性キャリア芯材粒子表面の樹脂被覆層が不均一になりやすく、結果として、帯電の均一性が得られなくなり、カブリ，トナー飛散が生じやすく、さらにキャリア付着も発生しやすくなる。
【００６６】
さらに、本発明の効果をより一層効果的にするためには、キャリアの見掛密度は好ましくは１．２〜３．２ｇ／ｃｍ²、より好ましくは１．５〜２．８ｇ／ｃｍ²とすることが良い。見掛密度が上記範囲の下限値より小さいと、キャリア付着が発生しやすくなり、上記範囲の上限値より大きいと二成分系現像剤の循環が悪くなり、トナー飛散が発生しやすくなるだけでなく、画質劣化も早まってしまう。
【００６７】
本発明をより効果的にするためにはキャリアの電流値は２０〜３００μＡ、より好ましくは３０〜２５０μＡ、更に好ましくは４０〜２００μＡであることが望ましい。
【００６８】
電流値が２０μＡより小さいと、キャリア表面での電荷の移動が十分に行われず、トナーへの帯電付与能が低下してしまい、カブリ，トナー飛散が発生しやすくなり、３００μＡより大きいと、感光体ドラムへのキャリア付着，バイアスリークが発生しやすくなり、画像欠陥が生じやすくなる。
【００６９】
キャリアの磁気特性は現像スリーブに内蔵されたマグネットローラーによって影響され、二成分系現像剤の現像特性及び搬送性に大きく影響を及ぼすものである。
【００７０】
本発明においては、マグネットローラーを内蔵した現像スリーブ上で、マグネットローラーを固定して現像スリーブを単体で回転し、磁性粒子からなるキャリアと絶縁性カラートナーを有する二成分系現像剤を現像担持体である現像スリーブ上で循環搬送し、該二成分系現像剤にて静電潜像保持体表面に保持された静電潜像を現像するに際して、▲１▼該マグネットローラーが反発極を有する極構成とし、▲２▼現像領域における磁束密度を５００〜１２００ガウスとし、▲３▼キャリアの飽和磁化が２０〜７０Ａｍ²／ｋｇのとき、カラー複写において画像の均一性や階調再現性にすぐれ好適である。
【００７１】
キャリアの飽和磁化が、７０Ａｍ²／ｋｇ（３０００エルステッドの印加磁場に対し）を超える場合であると、現像時に感光体上の静電潜像に対向した現像スリーブ上のキャリアとトナーにより構成されるブラシ状の穂立ちが固く締まった状態となり、階調性や中間調の再現が低下し、２０Ａｍ²／ｋｇ未満であると、トナー及びキャリアを現像スリーブ上に良好に保持することが困難になり、キャリア付着やトナー飛散が生じ易くなる。
【００７２】
ＭｇＯを含有するフェライトキャリアとしては、例えば特開昭５９−１１５９号公報，特開昭５８−１２３５５１号公報，特開昭５５−６５４０６号公報に記載されているが、これらは粒度分布がコントロールされておらず、単に１〜９μｍのトナーと組み合せただけでは、帯電の安定性，耐久性等満足のいくものではなく、本発明とは異なるものである。
【００７３】
さらに、特開平２−３３１５９号公報には、ＭｇＯを含有させても良い記載は有るが、積極的にＭｇＯを採用し、その表面活性を活用し、粒度分布のコントロール及び樹脂被覆キャリアの耐久性向上の示唆はなく、本発明とは異なるものである。
【００７４】
本発明に使用される硬化剤としては、下記一般式（ＩＩＩ）
【００７５】
【化３】

で示されるオキシムタイプの硬化剤が好適である。すなわち、シリコーン樹脂中の残存反応基の適度なコントロール、保存安定性、コストの面でオキシムタイプのシランカップリング剤は非常に優れている。
【００７６】
反応性の高いカップリング剤として酢酸タイプ（アセトキシシラン），アセトンタイプ（プロペノキシシラン）が知られているが、前述のキャリア芯材粒子とシリコーン樹脂との安定な反応を達成し、反応基を適度に残存させる条件設定が非常に難しいため、生産安定性に劣ることがわかっており、本発明には好ましくない。
【００７７】
本発明における硬化剤は、例えば、下記（１）〜（４）で示すものが挙げられる。
【００７８】
【化４】

【００７９】
上記硬化剤の添加量は、シロキサン固型分１００重量部に対して好ましくは０．１〜１０重量部、より好ましくは０．５〜５重量部が良い。０．１重量部未満では、十分な架橋効果が得られず、１０重量部を超える場合には、残渣が十分に除去できなかったり反応不十分の化合物が残存してしまい、帯電特性、強度が低下してしまう。本発明において、シロキサン固型分は、１２０℃における不揮発成分を示す。
【００８０】
本発明において、樹脂被覆層に用いられる反応性シリコーン樹脂に含有することができるアミノシランカップリング剤としては、例えば下記（５）〜（１３）に示すものが挙げられる。
【００８１】
【化５】

【００８２】
これらは、１種または２種以上使用することができる。この中で本発明に好適に使用されるのは、相溶性，反応性，安定性の点で、１個の水素原子を有する窒素原子を少なくとも一つ有する以下のカップリング剤である。
【００８３】
【化６】

【００８４】
上記カップリング剤の添加量は、シロキサン固型分１００重量部に対して好ましくは０．１〜８重量部、より好ましくは０．３〜５重量部が良い。０．１重量部未満では十分な添加効果が得られず、帯電性の劣化、被覆強度の低下が生じやすく、８重量部を超えると十分な反応が行われず、逆に被覆強度の低下が生じてしまう。
【００８５】
本発明においては、カップリング剤としては、さらに下記一般式（ＩＶ）
Ｒ_4-a−Ｓｉ−Ｘａ 式（ＩＶ）
（式中、Ｒ_4-aは、ビニル基，メタクリル基，エポキシ基，アミノ基，メルカプト基およびそれらの誘導体からなるグループから選択される置換基を示し、Ｘはハロゲンまたはアルコキシ基を示す。）で示されるカップリング剤を併用しても良い。
【００８６】
このようなカップリング剤としては、下記（１４）〜（１６）で示すものが挙げられる。
（１４）ＣＨ₃＝ＣＨ−Ｓｉ−（ＯＣＨ₃）₃
（１５）ＣＨ₃−Ｓｉ−（ＯＣＨ₃）₃
（１６）ＣＨ₃−Ｓｉ−（ＯＣ₂Ｈ₅）₃
【００８７】
磁性キャリア芯材粒子表面に樹脂被覆層を形成する方法としては、樹脂組成物を適当な溶媒に溶解し、得られる溶液中に磁性キャリア芯材粒子を浸漬し、しかる後に、脱溶媒，乾燥，高温焼付けする方法、あるいは磁性キャリア芯材粒子を流動化系中で浮遊させ、前記樹脂組成物の溶解した溶液を噴霧・塗付し、乾燥，高温焼付けする方法、単に磁性キャリア芯材粒子と樹脂組成物の粉体あるいは水系エマルションとを混合する方法等がいずれも使用できる。
【００８８】
本発明において好ましく用いられる方法は、ケトン類，アルコール類の如き極性溶媒を５重量％以上、好ましくは２０重量％以上含む溶媒１００重量部中に水を０．１〜５重量部、好ましくは０．３〜３重量部含有させた混合溶媒を使用する方法が、反応性シリコーンレジンを磁性キャリア芯材粒子に強固に付着させるために好ましい。水が０．１重量部未満では、反応性シリコーンレジンの加水分解反応が十分に行われず、磁性キャリア芯材粒子表面への薄層かつ均一な被覆が難しくなり、５重量部を超えると、反応制御が難しくなり、逆に被覆強度が低下してしまう。
【００８９】
本発明は、キャリアとトナーとを混合して二成分系現像剤を調製するが、その混合比率は二成分系現像剤中のトナー濃度として、１〜１２重量部、好ましくは２〜９重量％にすると通常良好な結果が得られる。トナー濃度が１重量％未満では画像濃度が低くなり、１２重量％を超えるとカブリや機内飛散を増加せしめ、二成分系現像剤の耐用寿命を短める。
【００９０】
本発明の二成分系現像剤は、上記のキャリアとトナーによって構成されるものであり、上記キャリアと組合わせて二成分系現像剤を構成するトナーの好ましい構成について説明する。
【００９１】
本発明に用いられるトナーは、トナー粒子及び０．００１乃至０．２μｍの重量平均粒径を有する表面処理された無機微粒子を外添剤として有するものであり、このトナー粒子及び外添剤を有するトナーは、１乃至９μｍの重量平均粒径を有するものがトナーの好ましい第１の形態である。
【００９２】
トナーの外添剤として用いる無機微粉体としては、例えばアルミナ、酸化チタン及びシリカが挙げられるが、この中でも特にアルミナ又は酸化チタン微粒子がトナーの帯電をより安定化するため好ましい。
【００９３】
さらに、上記無機微粉体は疎水化処理されていることが、トナーの帯電量の温度や湿度の如き環境依存性を少なくするため及びトナー表面からの遊離を防止するために良い。この疎水化処理剤としては、例えばシランカップリング剤，チタンカップリング剤，アルミニウムカップリング剤の如きカップリング剤，シリコーンオイル，フッ素系オイル，各種変性オイルの如きオイルが挙げられる。
【００９４】
上記の疎水化処理剤の中でも特にカップリング剤が、トナーの帯電の安定化，流動性付与の点で好ましい。
【００９５】
よって、本発明に用いる外添剤としては、特に好ましくは、カップリング剤を加水分解しながら表面処理を行ったアルミナまたは酸化チタン微粒子が、帯電の安定化，流動性の付与の点で極めて有効である。
【００９６】
上記の疎水化処理された無機微粉体は、好ましくは２０乃至８０％、より好ましくは４０乃至８０％の疎水化度を有することが良い。
【００９７】
無機微粉体の疎水化度が２０％より小さいと、高湿下での長期放置による帯電量低下が大きく、ハード側での帯電促進の機構が必要となり、装置の複雑化となり、疎水化度が８０％を超えると無機微粉体自身の帯電コントロールが難しくなり、結果として低湿下でトナーがチャージアップしやすくなる。
【００９８】
上記の疎水化処理された無機微粉体は、０．００１μｍ乃至０．２μｍ、好ましくは０．００５μｍ乃至０．１５μｍの重量平均粒径を有することが、トナーの流動性付与及び耐久時におけるトナー表面からの遊離防止の点で良い。
【００９９】
この重量平均粒径が０．００１μｍ未満の場合には、トナー粒子の表面に埋め込まれやすくなりトナー劣化が生じて耐久性が逆に低下しやすい。
【０１００】
０．２μｍを超える場合には、トナーの流動性が充分に得られ難く、トナーの帯電が不均一になりやすく、結果としてトナー飛散やカブリが生じやすい。
【０１０１】
上記の疎水化処理された無機微粉体は、４００ｎｍの光長における光透過率が４０％以上であることが好ましい。
【０１０２】
すなわち、本発明に使用される無機微粉体は、一次粒子径が小さいものであっても、実際トナー中に含有させた場合、必ずしも一次粒子の状態で分散しているわけでなく、二次粒子で存在している場合もありうる。したがって、いくら一次粒子径が小さくても、二次粒子としての挙動する実効径が大きくては、本発明の効果は低減してしまう。しかるに、可視領域の下限波長である４００ｎｍにおける光透過率が高いものほど、二次粒子径が小さく、流動性付与能，カラートナーの場合におけるＯＨＰの投影像の鮮明さの点で良好な結果が期待できる。４００ｎｍを選択した理由は紫外と可視の境界領域であり、光波長の１／２以下の粒径のものは透過するといわれていることからも、それ以上の波長の透過率は当然大きくなり、あまり意味のないものである。
【０１０３】
本発明において、トナー粒子及び外添剤を有するトナーは、１乃至９μｍ、好ましくは２乃至８μｍの重量平均粒径を有することが、高画質化と高耐久性の両立の点で良い。
【０１０４】
このトナーの重量平均粒径が１μｍ未満の場合には、キャリアとの混合性が低下し、トナー飛散，カブリ等の欠陥を生じ、９μｍを超える場合には、微小ドット潜像の再現性の低下、あるいは転写時の飛び散り等が生じ高画質化の妨げとなる。
【０１０５】
本発明に使用されるトナーに含有される着色剤としては、公知の染顔料、例えばフタロシアニンブルー、インダスレンブルー、ピーコックブルー、パーマネントレッド、レーキレッド、ローダミンレーキ、ハンザイエロー、パーマネントイエロー、ベンジジンイエローを使用することができる。その含有量としては、ＯＨＰ用フィルムの透過性に対し敏感に反映するよう、結着樹脂１００重量部に対して好ましくは１２重量部以下、より好ましくは０．５〜９重量部が良い。
【０１０６】
本発明に用いるトナーには必要に応じてトナーの特性を損ねない範囲で添加剤を混合しても良いが、そのような添加剤としては、例えばテフロン、ステアリン酸亜鉛、ポリフッ化ビニリデンの如き滑剤、あるいは定着助剤（例えば低分子量ポリエチレン、低分子量ポリプロピレンなど）、有機樹脂粒子等があげられる。
【０１０７】
本発明に用いるトナーの製造にあたっては、熱ロール、ニーダー、エクストルーダーの如き熱混練機によって構成材料を良く混練した後、機械的な粉砕，分級によって得る方法、結着樹脂溶液中に着色剤の如きトナー原料を分散した後、噴霧乾燥することにより得る方法、又は、結着樹脂を構成し得る重合性単量体に所定材料を混合した後、この乳化懸濁液を重合させることによりトナーを得る重合トナー製造方法が応用できる。
【０１０８】
本発明のトナーに使用する結着樹脂としては、各種の樹脂が用いられる。
【０１０９】
例えば、ポリスチレン、スチレン−ブタジエン共重合体、スチレン−アクリル共重合体の如きスチレン系共重合体、ポリエチレン、エチレン−酢酸ビニル共重合体、エチレン−ビニルアルコール共重合体のようなエチレン系共重合体、フェノール系樹脂、エポキシ系樹脂、アクリルフタレート樹脂、ポリアミド樹脂、ポリエステル樹脂、マレイン酸系樹脂があげられる。いずれの樹脂もその製造方法等は特に制約されるものではない。
【０１１０】
これらの樹脂の中で、特に負帯電能の高いポリエステル系樹脂を用いた場合に本発明の効果は絶大である。すなわち、ポリエステル系樹脂は、定着性にすぐれ、カラートナーに適している反面、負帯電能が強く帯電が過大になりやすいが、本発明の前述のキャリアと組合わせるトナーの結着樹脂としてポリエステル樹脂を用いると弊害は改善され、優れたトナーが得られる。
【０１１１】
特に、下記式（Ｖ）
【０１１２】
【化７】

（式中、Ｒはエチレンまたはプロピレン基を示し、ｘ，ｙはそれぞれ１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。）
で示されるビスフェノール誘導体もしくは置換体、をジオール成分とし、２価以上のカルボン酸、その酸無水物またはその低級アルキルエステルをカルボン酸成分（例えばフマル酸、マレイン酸、無水マレイン酸、フタル酸、テレフタル酸、トリメリット酸、ピロメリット酸）とし、上記ジオール成分と上記カルボン酸成分とを共縮重合したポリエステル樹脂がシャープな溶融特性を有するのでより好ましい。
【０１１３】
本発明に用いられるトナーは、重量平均粒径１〜９μｍを有し、かつポリエステル樹脂を有するバインダー樹脂を含み酸価１〜２０ＫＯＨｍｇ／ｇを有することが、トナーの好ましい第２の形態である。
【０１１４】
すなわち、上記の１〜２０ＫＯＨｍｇ／ｇの酸価を有するトナーを使用することで、特に上記の特定の磁性フェライト成分で形成された磁性キャリア芯材粒子を樹脂被覆層で被覆したキャリアとの帯電安定性が向上し、迅速帯電が可能となり、画像比率の高いオリジナルを使用した場合でも、長期にわたって、カブリ、トナー飛散のない二成分系現像剤が達成される。
【０１１５】
ここで、酸価が１ＫＯＨｍｇ／ｇより小さい場合は、帯電の立ち上がりが低下し、結果としてカブリが悪化しやすく、また、酸価が２０ＫＯＨｍｇ／ｇより大きいと、高湿下の帯電性が低下し結果としてカブリ、トナー飛散が生じてしまう。
【０１１６】
本発明に用いるトナーにおいては、トナーの酸価を１〜２０ＫＯＨｍｇ／ｇにコントロールし、かつトナーの低温定着性及び耐久性を向上させるために、結着樹脂の酸成分として三価以上の多価カルボン酸を０．１〜２０ｍｏｌ％、より好ましくは０．１〜１０ｍｏｌ％含有することが良い。さらに、好ましくは、前記ポリエステル樹脂を有するバインダー樹脂を含むトナーのガラス転移温度（Ｔｇ）が４５〜７０℃の範囲にあり、１０⁵ポイズの見掛け粘度を示す温度（Ｔｍ）が８〜１２０℃の範囲にあることが好ましい。
【０１１７】
特に好ましくは、前記のトナーの好ましい第１の形態で説明した上記式（Ｖ）で示されるビスフェノール誘導体もしくは置換体をジオール成分とし、２価以上のカルボン酸またはその酸無水物またはその低級アルキルエステルをカルボン酸成分（例えばフマル酸、マレイン酸、無水マレイン酸、フタル酸、テレフタル酸、トリメリット酸、ピロメリット酸）とし、上記ジオール成分と上記カルボン酸成分とを共縮重合したポリエステル樹脂がシャープな溶融特性を有するのでより好ましい。
【０１１８】
すなわち、ポリエステル系樹脂は、定着性に優れ、カラートナーに適している反面、負帯電能が強く、帯電が過大になりやすいが、前述の酸価１〜２０ＫＯＨｍｇ／ｇ、好ましくは２〜１８ＫＯＨｍｇ／ｇ、さらに好ましくは３〜１５ＫＯＨｍｇ／ｇの酸価を有するトナーおよび上記の磁性フェライト成分で形成された磁性キャリア芯材粒子表面を樹脂被覆層で被覆したキャリアとを使用することによって、上記弊害は改善され、優れた二成分系現像剤が得られる。
【０１１９】
本発明のトナーに使用する結着樹脂としては、さらに各種の材料樹脂を前述のポリエステル樹脂と組合せて使用しても良い。
【０１２０】
例えば、ポリスチレン、スチレン−ブタジエン共重合体、スチレン−アクリル共重合体等のスチレン系共重合体、ポリエチレン、エチレン−酢酸ビニル共重合体、エチレン−ビニルアルコール共重合体のようなエチレン系共重合体、フェノール系樹脂、エポキシ系樹脂、アクリルフタレート樹脂、ポリアミド樹脂、マレイン酸系樹脂があげられる。いずれの樹脂もその製造方法等は特に制約されるものではない。
【０１２１】
さらに、このトナーは、トナー粒子に外添剤を添加して用いることが好ましく、この外添剤としては、トナーの好ましい第１の形態で記載したものを用いることが好ましい。
【０１２２】
次に上記二成分系現像剤を用いた本発明の画像形成方法について説明する。
【０１２３】
本発明の画像形成方法は、トナー及びキャリアを有する二成分系現像剤を現像剤担持体上で循環搬送し、潜像保持体とそれに対向する現像剤担持体の現像領域で潜像保持体に保持されている潜像を該現像剤担持体上の二成分系現像剤のトナーで現像するものである。
【０１２４】
キャリアの磁気特性は現像スリーブに内蔵されたマグネットローラーによって影響され、現像剤の現像特性及び搬送性に大きく影響を及ぼすものである。
【０１２５】
本発明の画像形成方法においては、現像スリーブ（現像剤担持体）とこれに内蔵されたマグネットローラーのうち、例えばマグネットローラーを固定して現像スリーブを単体で回転し、磁性粒子からなるキャリアと絶縁性カラートナーからなる二成分系現像剤を現像スリーブ上で循環搬送し、該二成分系現像剤にて静電潜像保持体表面に保持された静電潜像を現像するものである。
【０１２６】
本発明の画像形成方法においては、前述の通り▲１▼該マグネットローラーが反発極を有する５極構成とし、▲２▼現像領域における磁束密度が５００〜１２００ガウスであり、▲３▼キャリアの飽和磁化が２０〜７０Ａｍ²／ｋｇである場合には、カラー複写において画像の均一性や階調再現性にすぐれ好適である。
【０１２７】
本発明の画像形成方法においては、現像領域で現像バイアスを印加して静電潜像を二成分系現像剤のトナーで現像することが好ましい。
【０１２８】
特に好ましい現像バイアスについて以下に詳述する。
【０１２９】
本発明の画像形成方法においては、現像領域で潜像保持体から現像剤担持体にトナーを向かわせる第１電圧と、現像剤担持体から潜像保持体にトナーを向かわせる第２電圧と、該第１電圧と該第２電圧の間の第３電圧を現像剤担持体に印加し、潜像保持体と現像剤担持体との間に現像電界を形成することにより、潜像保持体に保持されている潜像を現像剤担持体上の二成分系現像剤のトナーで現像することが好ましい。
【０１３０】
さらに、前述の潜像保持体から現像剤担持体にトナーを向かわせる第１電圧と現像剤担持体から潜像保持体にトナーを向かわせる第２電圧とを現像剤担持体に印加する合計時間（Ｔ₁）よりも、該第１電圧と該第２電圧との間の第３電圧を現像剤担持体に印加する時間（Ｔ₂）を長くすることが、潜像保持体上でトナーを再配列させ潜像に忠実に再現する目的で特に好ましい。
【０１３１】
具体的には、現像領域で潜像保持体と現像剤担持体との間に、潜像保持体から現像剤担持体にトナーが向かう電界と現像剤担持体から潜像保持体にトナーが向かう電界を少なくとも１回形成した後に、潜像保持体の画像部ではトナーが現像剤担持体から潜像保持体に向かい、潜像保持体の非画像部では、トナーが潜像保持体から現像剤担持体に向かう電界を所定時間形成することにより潜像保持体に保持されている潜像を現像剤担持体に担持されている二成分系現像剤のトナーで現像するものであり、この潜像保持体から現像剤担持体にトナーが向かう電界と現像剤担持体から潜像保持体にトナーが向かう電界を形成する合計時間（Ｔ₁）より潜像保持体の画像部ではトナーが現像剤担持体から潜像保持体に向かい、潜像保持体の非画像部では、トナーが潜像保持体から現像剤担持体に向かう電界を形成する時間（Ｔ₂）の方を長くすることが好ましい。
【０１３２】
前述の特定の現像電界、すなわち交番電界を形成して現像する現像方法で、定期的に交番をオフする現像電界を用いて現像を行なった場合にキャリア付着がより発生しづらいものである。この理由は、いまだ明確ではないが以下のように考えられる。
【０１３３】
すなわち、従来の連続的な正弦波あるいは矩形波においては、高画質濃度を達成しようとして電界強度を強くすると、トナーとキャリアは一体となって潜像保持体と現像剤担持体の間を往復運動し、結果として潜像保持体にキャリアが強く摺擦し、キャリア付着が発生する。この傾向は微粉キャリアが多い程顕著である。
【０１３４】
しかるに、本発明の如き特定の交流電界を印加すると、１パルスではトナーあるいはキャリアが現像剤担持体と潜像保持体間を往復しきらない往復運動をするため、その後の潜像保持体の表面電位と現像バイアスの直流成分の電位差Ｖ_contがＶ_cont＜０の場合には、Ｖ_contがキャリアを現像剤担持体から飛翔させるように働くが、キャリアの磁気特性とマグネットローラーの現像領域での磁束密度をコントロールすることによって、キャリア付着は防止でき、Ｖ_cont＞０の場合には、磁界の力およびＶ_contがキャリアを現像剤担持体側に引きつけるように働き、キャリア付着は発生しない。
【０１３５】
本発明の画像形成方法に用いることが可能な静電潜像担持体の好ましい形態について図６を用いて説明する。
【０１３６】
静電潜像保持体１は導電性支持体４１上に感光層４３及び保護層４４が設けられており、少なくとも該保護層４４が静電潜像保持体１表面の摩擦抵抗を低下させる為に、フッ素原子含有樹脂粒子を含有しており、且つ該保護層４４が機械研磨され、該保護層４４の平均面粗さが、好ましくはＪＩＳ規格Ｂ０６１で定義される１０点平均面粗さＲ_z（以下、単に平均面粗さと略す）が０．０１〜１．５μｍであることが良い。
【０１３７】
この平均面粗さが上記範囲内であればクリーニングブレード５０と静電潜像保持体１表面との摩擦も充分に小さく、また繰り返し使用によっても画像欠陥が表れてくる事はなく、さらに、ハイライト再現も非常に優れたものになる。
【０１３８】
静電潜像保持体１表面の摩擦係数を有効に下げ得るフッ素原子含有樹脂微粒子の含有率は、保護層４４中においては保護層４４の全重量を基準として５〜４０重量％、好ましくは１０〜４０重量％が良い。保護層４４の膜厚は、好ましくは０．０５μｍから８．０μｍの範囲であり、より好ましくは０．１μｍから６．０μｍの範囲であることが良い。
【０１３９】
本発明において感光層４３部分にもフッ素原子含有樹脂微粒子を含有する場合には、薄膜の保護層４４に較べて感光層４３は厚いため、該微粒子の含有量は制限される。具体的には、感光層４３中の含有率は、感光層４３の全重量を基準として好ましくは１０重量％以下であり、より好ましくは７重量％以下である。
【０１４０】
感光層４３中のフッ素原子含有樹脂微粒子量を制限しても、感光層４３の総厚が厚い場合、特に、フォトキャリアーが主に感光層４３の支持体側で発生する場合には、光散乱による感度劣化、画像均一性の低下が著しい。感光層４３が薄すぎても、感光層４３の電気容量の増加による感度低下や帯電能の低下を引き起こすことがある。さらに、感光層４３中に該微粒子を含まない場合においても、感光層４３を極端に厚くすることは好ましくない。その理由は、該微粒子を含む保護層４４が感光層４３の上に積層されるため、保護層４４は光散乱層となり、特に、フォトキャリアーが主に感光層の支持体側で発生する場合、フォトキャリアーの発生部が光散乱層から遠いほど、つまり、感光層４３が厚いほど散乱後の光の光路長が長くなり、光散乱の影響が大きくなってしまうからである。
【０１４１】
従って、感光層４３の厚さは保護層４４との合計で好ましくは１０〜３５μｍ、より好ましくは１５〜３０μｍである。感光層４３中に含有される該微粒子はできるだけ少量であることが好ましく、それで感光層４３と保護層４４との合計膜厚中の該微粒子の平均含有率は、感光層４３と保護層４４の全重量を基準として１７．５重量％以下であることが良い。
【０１４２】
本発明において、静電潜像保持体に用いられるフッ素原子含有樹脂微粒子はポリテトラフルオロエチレン、ポリクロロトリフルオロエチレン、ポリフッ化ビニリデン、ポリジクロロジフルオロエチレン、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体、テトラフルオロエチレン−エチレン共重合体、及びテトラフルオロエチレン−ヘキサフルオロプロピレン−パーフルオロアルキルビニルエーテル共重合体から選ばれた１種または２種以上から構成されているものである。市販のフッ素原子含有樹脂微粒子をそのまま用いることが可能である。０．３万〜５００万の分子量のものが使用可能であり、０．０１〜１０μｍ、好ましくは０．０５〜２．０μｍの粒径のものが使用可能である。
【０１４３】
本発明において、静電潜像保持体の感光層４３は有機光導電性物質として、少なくとも電荷発生材料及び電荷輸送材料を含有する。
【０１４４】
電荷発生材料の例としては、フタロシアニン顔料、多環キノン顔料、トリスアゾ顔料、ジスアゾ顔料、アゾ顔料、ペリレン顔料、インジゴ顔料、キナクリドン顔料、アズレニウム塩染料、スクアリウム染料、シアニン染料、ピリリウム染料、チオピリリウム染料、キサンテン色素、キノンイミン色素、トリフェニルメタン色素、スチリル色素、セレン、セレン−テルル合金、アモルファスシリコン、硫化カドミウムが挙げられる。
【０１４５】
電荷輸送材料の例としては、ピレン化合物、Ｎ−アルキルカルバゾール化合物、ヒドラゾン化合物、Ｎ，Ｎ−ジアルキルアニリン化合物、ジフェニルアミン化合物、トリフェニルアミン化合物、トリフェニルメタン化合物、ピラゾリン化合物、スチリル化合物、スチルベン化合物、ポリニトロ化合物、ポリシアノ化合物、さらに、これらの化合物をポリマー上に固定したペンダントポリマーが挙げられる。
【０１４６】
前記のフッ素原子含有樹脂微粒子、電荷発生材料、電荷輸送材料を、それぞれ成膜性を有する結着樹脂中に分散、含有させて、各保護層、感光層を形成する場合が多い。その様な結着樹脂としては、ポリエステル、ポリウレタン、ポリアクリレート、ポリエチレン、ポリスチレン、ポリカーボネート、ポリアミド、ポリプロピレン、ポリイミド、フェノール樹脂、アクリル樹脂、シリコーン樹脂、エポキシ樹脂、ユリア樹脂、アリル樹脂、アルキッド樹脂、ポリアミド−イミド、ナイロン、ポリサルフォン、ポリアリルエーテル、ポリアセタール、ブチラール樹脂が挙げられる。
【０１４７】
次に、静電潜像保持体の層構成を述べる。導電性支持体４１は、鉄、銅、金、銀、アルミニウム、亜鉛、チタン、鉛、ニッケル、スズ、アンチモン、インジウムの如き金属や合金、或いは前記金属の酸化物、カーボン、導電性ポリマーが使用可能である。形状は円筒形、円柱形の如きドラム形状と、ベルト形状、シート状のものとがある。前記導電性材料は、そのまま成形加工される場合、塗料として用いられる場合、蒸着される場合や、エッチング、プラズマ処理により加工される場合もある。塗料の場合には、支持体として前記の金属や合金は勿論、紙、プラスチックも用いられる。
【０１４８】
静電潜像保持体１における感光層４３は、単層構成であっても、積層構成であってもよい。積層構成の場合には、少なくとも電荷発生層４３ａと電荷輸送層４３ｂにより構成されるが、導電性支持体４１側に電荷発生層４３ａが設けられる場合と、電荷輸送層４３ｂが設けられる場合とでは帯電極性、使用するトナー極性が異なる。電荷発生層４３ａの膜厚としては、好ましくは０．００１〜６μｍが良く、より好ましくは０．０１〜２μｍである。電荷発生層４３ａに含有される電荷発生材料の含有率は、電荷発生層の全重量を基準として１０〜１００重量％であることが好ましく、より好ましくは５０〜１００重量％である。電荷輸送層の厚さは、前記感光層４３の膜厚から前記電荷発生層４３ａの膜厚を差し引いたものである。電荷輸送層４３ｂ中に含まれる電荷輸送材の含有量は、電荷発生層の全重量を基準として２０〜８０重量％が好ましく、より好ましくは３０〜７０重量％である。
【０１４９】
導電性支持体４１と感光層４３との間に下引き層４２を設けても良い。下引き層４２は、界面での電荷注入制御や接着層として機能する。下引き層４２は、主に結着樹脂から成るが、前記金属や合金、またはそれらの酸化物、塩類、界面活性剤などを含んでいてもよい。下引き層４２を形成する結着樹脂としては、前記感光層４３の結着樹脂として挙げたものを使用でき、下引き層の膜厚は、０．０５〜７μｍが好ましく、より好ましくは０．１〜２μｍである。
【０１５０】
保護層は、前述した様に感光層の上に設けられ、少なくとも高濃度のフッ素原子を含有する樹脂微粒子と結着樹脂とから構成されることが好ましい。
【０１５１】
静電潜像保持体の製造方法として蒸着又は塗布の方法が用いられる。塗布による方法は、薄膜から厚膜まで広い範囲で、しかもさまざまな組成の膜が形成可能である。具体的には、バーコレーター、ナイフコーター、浸漬塗布、スプレー塗布、ビーム塗布、静電塗布、ロールコーター、アトライター、粉体塗布の如き塗布方法を用いて塗布される。
【０１５２】
保護層を塗布する際に用いられる塗料は、結着樹脂及び溶剤中に、前記フッ素原子含有樹脂微粒子を分散させることにより得られる。分散の方法としては、ボールミル、超音波、ペイトンシェーカー、レッドデビル、サンドミルの如き方法が用いられる。導電性微粉や顔料、電荷発生材料が顔料の場合も同様の分散方法を用いることができる。
【０１５３】
本発明の画像形成方法を実施し得る画像形成装置を図１を用いて説明する。
【０１５４】
図１において、画像形成装置は、静電潜像保持体としての感光ドラム１を有し、現像装置４にて、現像容器１６の内部は、隔壁１７によって現像室（第１室）Ｒ₁と撹拌室（第２室）Ｒ₂とに区画され、撹拌室Ｒ₂の上方には隔壁１７を隔ててトナー貯蔵室Ｒ₃が形成されている。現像室Ｒ₁及び撹拌室Ｒ₂内には現像剤１９が収容されており、トナー貯蔵室Ｒ₃内には補給用トナー（非磁性トナー）１８が収容されている。なお、トナー貯蔵室Ｒ₃には補給口２０が設けられ、補給口２０を経て消費されたトナーに見合った量の補給用トナー１８が撹拌室Ｒ₂内に落下補給される。
【０１５５】
現像室Ｒ₁内には搬送スクリュー１３が設けられており、この搬送スクリュー１３の回転駆動によって現像室Ｒ₁内の現像剤１９は、現像スリーブ１１の長手方向に向けて搬送される。同様に、貯蔵室Ｒ₂内には搬送スクリュー１４が設けられ、搬送スクリュー１４の回転によって、補給口２０から撹拌室Ｒ₂内に落下したトナーを現像スリーブ１１の長手方向に沿って搬送する。
【０１５６】
現像剤１９は、非磁性トナーと磁性キャリアとを有した二成分系現像剤である。
【０１５７】
現像容器１６の感光ドラム１に近接する部位には開口部が設けられ、該開口部から現像スリーブ１１が外部に突出し、現像スリーブ１１と感光ドラム１との間には間隙が設けられている。非磁性材にて形成される現像スリーブ１１には、バイアスを印加するためのバイアス印加手段３０が配置されている。
【０１５８】
現像スリーブ１１内に固定された磁界発生手段としてのマグネットローラ、即ち磁石１２は、上述したように、現像磁極Ｓ₂とその下流に位置する磁極Ｎ₂と、現像剤１９を搬送するための磁極Ｎ₃、Ｓ₁、Ｎ₁とを有する。磁石１２は、現像磁極Ｓ₂が感光ドラム１に対向するように現像スリーブ１１内に配置されている。現像磁極Ｓ₂は、現像スリーブ１１と感光ドラム１との間の現像部の近傍に磁界を形成し、該磁界によって磁気ブラシが形成される。
【０１５９】
現像スリーブ１１の上方に配置され、現像スリーブ１１上の現像剤１９の層厚を規制する規制ブレード１５は、アルミニウム、ＳＵＳ３１６の如き非磁性材料で作製される非磁性ブレード１５の端部と現像スリーブ１１面との距離は３００〜１０００μｍ、好ましくは４００〜９００μｍである。この距離が３００μｍより小さいと、磁性キャリアがこの間に詰まり現像剤層にムラを生じやすいと共に、良好な現像を行うのに必要な現像剤を塗布することが出来ず、濃度の薄いムラの多い現像画像しか得られないという問題点がある。現像剤中に混在している不用粒子による不均一塗布（いわゆるブレードづまり）を防止するためには４００μｍ以上が好ましい。１０００μｍより大きいと現像スリーブ１１上へ塗布される現像剤量が増加し所定の現像剤層厚の規制が行えず、感光ドラム１への磁性キャリア粒子の付着が多くなると共に現像剤の循環，非磁性ブレード１５による現像規制が弱まりトナーのトリボが不足しカブリやすくなるという問題点がある。
【０１６０】
角度θ１は−５°〜３５°、好ましくは０°〜２５°である。θ１＜−５°の場合、現像剤に働く磁気力，鏡映力，凝集力等により形成される現像剤薄層がまばらでムラの多いものとなり、θ＞３５°の場合は非磁性ブレードでは現像剤塗布量が増加し、所定の現像剤量を得ることが難しい。
【０１６１】
この磁性キャリア粒子層は、スリーブ１１が矢印方向に回転駆動されても磁気力，重力に基づく拘束力とスリーブ１１の移動方向への搬送力との釣合によってスリーブ表面から離れるに従って動きが遅くなる。もちろん重力の影響により落下するものもある。
【０１６２】
従って磁極Ｎ₁とＮ₂の配設位置と磁性キャリア粒子の流動性及び磁気特性を適宜選択する事により磁性キャリア粒子層はスリーブに近い程磁極Ｎ₁方向に搬送し移動層を形成する。この磁性キャリア粒子の移動により現像スリーブ１１の回転に伴なって現像領域へ現像剤は搬送され現像に供される。２１は、上流側トナー飛散抑制部であり、２２は下流側トナー飛散抑制部であり、この上流側トナー飛散抑制部２１及び下流側トナー飛散抑制部２２によってトナー飛散の発生を抑えている。
【０１６３】
本発明の画像形成方法を実施し得る画像形成装置の他の例を図７を用いて説明する。
【０１６４】
図７に示す現像装置は、現像容器１０２の現像室１４５内に、矢印ａ方向に回転される静電潜像保持体１０１に対向して現像剤担持体としての非磁性現像スリーブ（現像剤担持体）１２１を備え、この現像スリーブ１２１内に磁界発生手段としての磁性ローラー１２２が不動に放置されており、磁性（マグネット）ローラー１２２は略頂部の位置から矢印ｂの回転方向に順にＳ₁、Ｎ₁、Ｓ₂、Ｎ₂、Ｎ₃に着磁されている。
【０１６５】
現像室１４５内には、トナー１４０と磁性キャリア１４３とを混合した二成分系現像剤１４１が収容されている。
【０１６６】
この現像剤１４１は、現像室１４５の一端で上端開口の隔壁１４８の図示しない一方の開口を通って現像容器１０２の撹拌室１４２内に送られると、トナー室１４７から撹拌室１４２内に供給されたトナー１４０が補給され、撹拌室１４２内の第１現像剤撹拌・搬送手段１５０によって混合しながら、撹拌室１４２の他端に搬送される。撹拌室１４２の他端に搬送された現像剤１４１は、隔壁１４８の図示しない他方の開口を通って現像室１４５内に戻され、そこで現像室１４５内の第２現像剤撹拌・搬送手段１５１と、現像室１４５内上部で搬送手段１５１による搬送方向と逆方向に現像剤を搬送する第３現像剤撹拌・搬送手段により、撹拌・搬送されながら現像スリーブ１２１に供給される。
【０１６７】
現像スリーブ１２１に供給された現像剤１４１は、上記の磁石ローラ１２２の磁力の作用により磁気的に拘束され、現像スリーブ１２１上に担持され、現像スリーブ１２１の略頂部上に設けた現像剤規制部材ブレード１２３での規制によって現像スリーブ１２１上で現像剤１４１の薄層に形成されながら、現像スリーブ１２１の矢印ｂ方向への回転に伴い静電潜像保持体１０１と対向した現像部１１０へと搬送され、そこで静電潜像保持体１０１上の静電潜像の現像に供される。現像に消費されなかった残余の二成分系現像剤１４１は、現像スリーブ１２１の回転により現像容器１０２内に回収される。１０３は上流側トナー飛散抑制部であり、１０４は下流側トナー飛散抑制部であり、この上流側トナー飛散抑制部１０３及び下流側トナー飛散抑制部１０４によってトナー飛散の発生を抑えている。
【０１６８】
現像容器１０２内では同極のＮ₂、Ｎ₃間での反発磁界により現像スリーブ１２１上に磁気的に拘束されている現像残りの残余の二成分系現像剤１４１を剥取るようになっている。上記の磁極Ｎ₂により二成分系現像剤１４１が磁力線に沿って穂立ちしたときのトナー飛散を防止するために、現像容器１０２の下部には弾性シール部材１３１がその一端を現像剤１４１と接触するようにして、固定、設置されている。
【０１６９】
さらに、本発明者らは、カラー画像形成方法の画像濃度、ハイライト再現性、細線再現性について鋭意検討した結果、後述の特定の粒度分布を有したトナーを、前述の特定の現像電界を形成した現像方法を用いた画像形成方法に用いたときに、高画像濃度、ハイライト再現、細線再現に優れた高画質化が達成できることを見い出したのである。
【０１７０】
すなわち、本発明で用いられるトナーは、少なくともトナー粒子と外添剤を含有し、該トナーの重量平均粒径が３〜７μｍであり、該トナーは５．０４μｍ以下の粒径を有するトナーを４０個数％より多く含有し、４μｍ以下の粒径を有するトナーを１０〜７０個数％含有し、８μｍ以上の粒径を有するトナーを２〜２０体積％含有し、１０．０８μｍ以上の粒径を有するトナーを０〜６体積％含有しているものが好ましい。
【０１７１】
前述の粒度分布を有するトナーは、感光体上に形成された潜像に忠実に再現することが可能であり、網点及びデジタルのような微小なドット潜像の再現性にも優れ、特にハイライト部の階調性及び解像性に優れた画像を与える。更に、コピー又はプリントアウトを続けた場合でも高画質を保持し、且つ、高濃度の画像の場合でも、従来の非磁性トナーより少ないトナー消費量で良好な現像を行うことが可能であり、経済性及び、複写機又はプリンター本体の小型化にも利点を有するものである。
【０１７２】
しかしながら、本来、潜像再現性に優れたトナーであっても従来の連続的な正弦波あるいは矩形波においては、ハイライト潜像のように現像コントラストの小さい潜像にあっては電界強度が十分でないため、連続パルスでは、トナーが潜像保持体に到達しない割合が大きくなる。すなわち、上記の条件下のバイアスにおいては、トナーは現像剤担持体から潜像保持体に到達しないような振動運動をする。
【０１７３】
しかるに、本発明は現像領域で後述するような特定の現像電界を形成したことで、がさつきのない、良好なハイライト画像を得ることができる。すなわち、１パルスではトナーが現像剤担持体と静電潜像保持体間を往復しきらないよう振動運動するのは同じであるが、その後静電潜像保持体の表面電位と現像バイアスの直流成分の電位差Ｖ_contがＶ_cont＜０の場合には直流成分が現像剤担持体側にトナーを引きつけるように働き、トナーが現像剤担持体側に偏り、逆にＶ_cont＞０の場合においては直流成分が潜像電位に応じて、静電潜像保持体側にトナーを引きつけるように働き、潜像電位にみあった量のトナーが静電潜像保持体側に偏る。また、このような条件下で現像すると、潜像保持体上に到達したトナーはそこで振動を繰り返し、潜像部へ集中してくる。このためドット形状が均一化されてムラのない良好な画像を得ることができる。
【０１７４】
以上のことから、上記のような条件の現像バイアスで潜像を顕像化すると、ハイライト潜像の場合においても、ドットの欠落が発生しなくなる。さらに、潜像保持体上で振動を繰り返すことにより、潜像部にトナーが集中し、１つ１つのドットが忠実に再現され、二成分系現像剤においては磁気ブラシの接触状態によるムラのない均一なハーフトーン画像が出力できるようになる。
【０１７５】
以下に、本発明における測定方法について述べる。
【０１７６】
（１）キャリアの磁気特性の測定
装置は、ＢＨＵ−６０型磁化測定装置（理研測定製）を用いる。測定試料は約１．０ｇ秤量し内径７ｍｍφ、高さ１０ｍｍのセルにつめ、前記の装置にセットする。測定は印加磁場を徐々に加え最大３，０００エルステッドまで変化させる。次いで印加磁場を減少せしめ、最終的に記録紙上に試料のヒステリシスカーブを得る。これより、飽和磁化，残留磁化，保磁力を求める。
【０１７７】
（２）キャリアの粒度分布の測定
装置は、マイクロトラック粒度分析計（日機装株式会社）のＳＲＡタイプを使用し０．７〜１２５μｍのレンジ設定で行い、体積基準から５０％粒径を算出した。
【０１７８】
（３）キャリアの電流値の測定
▲１▼ キャリア８００ｇを秤量し、１５分以上環境に暴露する。（室内温度２２〜２５℃、湿度５０〜５４％）
▲２▼ マグネットローラーを内蔵し、穂立規制ブレードを設けた導電性のスリーブと対向して１ｍｍの距離に対向電極を設けた装置を用意する。
▲３▼ スリーブと対向電極間にキャリアを磁気吸引させる。
▲４▼ スリーブ内のマグネットローラーを回転させて対向電極に穂立させたキャリアを接触させ、スリーブと対向電極の間に５００Ｖの直流電圧を負荷し、直列させた１ＭΩ，１０ＫΩの抵抗の両端における電圧降下を測り、この値から電流値を計算で求める。
【０１７９】
（４）トナー粒度（重量平均粒径）の測定
トナーの平均粒径及び粒度分布はコールターカウンターＴＡ−ＩＩ型あるいはコールターマルチサイザー（コールター社製）を用いて測定可能であるが、本発明においてはコールターマルチサイザー（コールター社製）を用い、個数分布，体積分布を出力するインターフェイス（日科機製）及びＰＣ９８０１パーソナルコンピューター（ＮＥＣ製）を接続し、電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。たとえば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜５ｍｌ加え、更に測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行ない前記コールターマルチサイザーによりアパーチャーとして１００μｍアパーチャーを用いて、２μｍ以上のトナーの体積，個数を測定して体積分布と個数分布とを算出した。それから、本発明に係わる体積分布から求めた体積基準の体積平均粒径（Ｄ_v：各チャンネルの中央値をチャンネルの代表値とする）及び重量平均粒径（Ｄ₄）、個数分布から求めた個数基準の長さ平均粒径（Ｄ₁）、及び体積分布から求めた体積基準の粒子比率（８．００μｍ以上及び３．１７μｍ以下））、個数分布から求めた個数基準の粒子比率（５μｍ以下及び３．１７μｍ以下）を求めた。
【０１８０】
（５）外添剤（無機微粉体）の重量平均粒径の測定
測定装置はマイクロトラック粒度分析計Ｍｏｄｅｌ ９２３０ＵＰＡ（日機装（株）社製）を使用し、以下の如く測定する。
１） ５０ｃｃのガラスビーカーにエタノール２０ｍｌを入れる。
２） Ｒｅｆｌｅｃｔｅｄ Ｐｏｗｅｒが２００ｍＶとなるように試料を添加する。
３） 超音波発生機ＵＤ２００（トミー精工（株）製）で３分間分散させる。
４） サンプル分散液を６ｍｌ採り、２２℃の温度条件で３回測定し、体積粒径分布より、重量平均粒径を算出し平均値をとる。
【０１８１】
（６）無機微粉体の疎水化度の測定
メタノール測定試験は、疎水化された表面を有する無機微粉体の疎水化度を確認する実験的試験である。
【０１８２】
処理された無機微粉体の疎水化度を評価するために本明細書において規定される“メタノール滴定試験”は次の如く行う。
【０１８３】
供試無機微粉体０．２ｇを容量２５０ｍｌの三角フラスコ中の水５０ｍｌに添加する。メタノールをビューレットから無機微粉体の全量が湿潤されるまで滴定する。この際フラスコ内の溶液はマグネチックスターラーで常時撹拌する。その終点は無機微粉体の全量が液体中に懸濁されることによって観察され、疎水化度は終点に達した際のメタノールおよび水の液状混合物中のメタノールの百分率として表わされる。
【０１８４】
（７）光透過率の測定
▲１▼ 試料 ０．１０ｇ
アルキッド樹脂 １３．２０ｇ
（大日本インキ製ベッコゾール１３２３−６０−ＥＬ）
メラミン樹脂 ３．３０ｇ
（大日本インキ製スーパーベッカミンＪ−８２０−６０）
シンナー ３．５０ｇ
（関西ペイント製アラミックシンナー）
ガラスメディア ５０．００ｇ
【０１８５】
上記配合を１５０ｃｃガラス瓶に採取し、レッドデビル社製ペイントコンディショナーにて１時間分散を行う。
【０１８６】
▲２▼ 分散終了後、ＰＥＴフィルムの表面とドクターブレードとの間隔を２ｍｍに設定し、ＰＥＴフィルムに前記分散液を塗布する。
【０１８７】
▲３▼ ▲２▼を１２０℃×１０分間加熱し、焼き付けを行う。
【０１８８】
▲４▼ ▲３▼のシートを日本分光製Ｕ−ＢＥＳＴ ５０にて３２０〜８００ｎｍの範囲で光透過率を測定した。
【０１８９】
（８）比表面積の測定
島津粉比表面積測定装置（ＳＳ−１００型）を用いて下記の手順により行う。
１） 試料鉄粉充填のためパウダーテスターのオートスライダックの電源を入れ１００Ｖに調整する。
２） パスダーテスターの切替えスイッチをタップにしてタイマーを１分間に調整する（５０回±１回／１分間）。
３） プラスチック試料筒にフルイ板を入れその上にろ紙を一枚敷き、その上に試料を試料筒の１／３まで入れる。
４） 試料筒をパウダーテスターのタップ架台にセットし、スタートボタンを入れる（１分間タップ）。
５） さらにタップした試料筒に試料を試料筒の２／３まで入れる。
６） 上記４項と同一作業を行う。
７） 試料筒の上に補足筒（プラスチック）を差し込み、試料をその上から山盛りに入れる。
８） 上記４項、６項と同一作業を行う。
９） タップした試料筒をタップ架台から取り出し、補足筒を抜き取り余分の試料をヘラでカットする。
１０） 比表面積の測定管のＳ目盛まで水を満たす。
１１） 試料筒を測定管に接続する（試料充填後、すり合わせ面にグリスを塗る）。
１２） 下部流出口のコックを開き、測定管の水面が０目盛りを通過する時に、ストップウォッチを始動させる（下部流出水はビーカーで受ける）。
１３） ２０目盛（単位はｃｃ）まで水面が低下する時間を計る。
１４） 試料筒を取り外し、試料の重量を測定する。
１５） 比表面積の計算
【０１９０】
下記の計算式で比表面積を算出する。
【０１９１】
【数１】

【０１９２】
ＳＷ：粉体の比表面積 ｃｍ²／ｇ
ｅ：試料充填層の空隙率
ρ：粉体の密度 ｇ／ｃｍ²
η：流体の粘性係数 ｇ／ｃｍ・ｓｅｃ
Ｌ：試料層の厚さ ｃｍ
Ｑ：試料層透過流体量 ｃｃ
ΔＰ：試料層両端の圧力差 ｇ／ｃｍ²
Ａ：試料層の断面積 ｃｍ²
ｔ：Ｑｃｃの流体（空気）が試料層を透過するのに要する時間 ｓｅｃ
Ｗ：試料の重量 ｇ
【０１９３】
（９）キヤリアの密度の測定
島津製作所製のアキュピック１３３０を使用し、キャリアを１０ｃｍ²の測定用セルにごく軽くタッピングしながら容器の８分目程度まで充填し、４０℃に設定した真空乾燥機で２４時間乾燥した後、重量を測定してから本体に挿入し、ヘリウムガスの充填圧力を１３４．４５ＫＰａで１０回パージした後、充填圧力１３４．４５ＫＰａ、平衡圧０．０３４５ＫＰａで５回測定した平均値をキャリアの密度とした。
【０１９４】
（１０）酸価測定法
サンプル２〜１０ｇを２００〜３００ｍｌの三角フラスコに秤量し、メタノール：トルエン＝３０：７０の混合溶媒約５０ｍｌ加えて樹脂を溶解する。溶解性が悪いようであれば少量のアセトンを加えてもよい。０．１％のブロムチモールブルーとフェノールレッドの混合指示薬を用い、あらかじめ標定されたＮ／１０カ性カリ〜アルコール溶液で滴定し、アルコールカリ液の消費量からつぎの計算で酸価を求める。
【０１９５】
酸価＝ＫＯＨ（ｍｌ数）×Ｎ×５６．１／試料重量
（ただしＮはＮ／１０ＫＯＨのファクター）
【０１９６】
（１１）ガラス転移温度Ｔｇの測定
本発明においては、示差熱分析測定装置（ＤＳＣ測定装置）、ＤＳＣ−７（パーキンエルマー社製）を用い測定する。
【０１９７】
測定試料は５〜２０ｍｇ、好ましくは１０ｍｇを精密に秤量する。
【０１９８】
これをアルミパン中に入れ、リファレンスとして空のアルミパンを用い、測定温度範囲３０℃〜２００℃の間で、昇温速度１０℃／ｍｉｎで常温常湿下で測定を行う。
【０１９９】
この昇温過程で、温度４０〜１００℃の範囲におけるメインピークの吸熱ピークが得られる。
【０２００】
このときの吸熱ピークが出る前と出た後でのベースラインの中間点の線と示差熱曲線との交点を本発明におけるガラス転移温度Ｔｇとする。
【０２０１】
（１２）軟化点温度（Ｔｍ）
フローテスターＣＦＴ−５００型（島津製作所製）を用いる。試料は６０ｍｅｓｈパス品を約１．０ｇ秤量する。これを成形器を使用し、１００ｋｇ／ｃｍ²の加重で１分間加圧する。
【０２０２】
この加圧サンプルを下記の条件で、常温常湿（温度約２０〜３０℃、湿度３０〜７０％ＲＨ）でフローテスター測定を行い、温度−見掛け粘度曲線を得る。得られたスムース曲線より、試料が５０体積％流出した時の温度（＝Ｔ_1/2）を求め、これを軟化点温度（Ｔｍ）とする。
【０２０３】
ＲＡＴＥ ＴＥＭＰ ６．０ Ｄ／Ｍ（℃１分）
ＳＥＴ ＴＥＭＰ ５０．０ ＤＥＧ（℃）
ＭＡＸ ＴＥＭＰ １８０．０ ＤＥＧ
ＩＮＴＥＲＶＡＬ ３．０ ＤＥＧ
ＰＲＥＨＥＡＴ ３００．０ ＳＥＣ（秒）
ＬＯＡＤ ２０．０ ＫＧＦ（ｋｇ）
ＤＩＥ（ＤＩＡ） １．０ ＭＭ（ｍｍ）
ＤＩＥ（ＬＥＮＧ） １．０ ＭＭ（ｍｍ）
ＰＬＵＮＧＥＲ １．０ ＣＭ²（ｃｍ²）
【０２０４】
【実施例】
以下に本発明の実施例を示すが、本発明はなんらこれに限定されるものではない。「部」は「重量部」を意味する。
【０２０５】
（磁性キャリア芯材粒子の製造例１〜３）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）２０部，ＭｎＯ ２０部，Ｆｅ₂Ｏ₃ ６０部をそれぞれ微粒化した後、水を添加混合し造粒した後、１１００℃にて焼成し表１に示すような粒度調整をした後、平均粒径３５．７μｍ，２５．６μｍ及び６１．３μｍのフェライトキャリア芯材粒子（飽和磁化５８Ａｍ²／ｋｇ）Ａ，Ｂ及びＣをそれぞれ得た。
【０２０６】
（磁性キャリア芯材粒子の製造例４）
ＭｇＯ １５部，ＮｉＯ １０部，Ａｌ₂Ｏ₃ ３部，Ｆｅ₂Ｏ₃ ７２部を使用する以外は製造例１と同様にして、平均粒径３６．３μｍのフェライトキャリア芯材粒子（飽和磁化６０Ａｍ²／ｋｇ）Ｄを得た。
【０２０７】
（磁性キャリア芯材粒子の製造例５）
Ａｇ₂Ｏ（溶解度１．７４ｍｇ／１００ｍｌ）３部，ＭｎＯ ２７部，Ｆｅ₂Ｏ₃ ７０部を使用する以外は製造例１と同様にして、平均粒径３９．３μｍのフェライトキャリア芯材粒子（飽和磁化６５Ａｍ²／ｋｇ）Ｅを得た。
【０２０８】
（磁性キャリア芯材粒子の製造例６）
ＢａＯ（溶解度１ｇ以上／１００ｍｌ）２０部，ＺｎＯ ２０部，Ｆｅ₂Ｏ₃ ６０部を使用する以外は製造例１と同様にして、平均粒径３６．０μｍのフェライトキャリア芯材粒子（飽和磁化５７Ａｍ²／ｋｇ）Ｆを得た。
【０２０９】
（磁性キャリア芯材粒子の製造例７）
Ｋ₂Ｏ（溶解度１ｇ以上／１００ｍｌ）５部，ＮｉＯ ２０部，Ｆｅ₂Ｏ₃ ７３部を使用する以外は製造例１と同様にして、平均粒径３６．８μｍのフェライトキャリア芯材粒子（飽和磁化５５Ａｍ²／ｋｇ）Ｇを得た。
【０２１０】
（磁性キャリア芯材粒子の製造例８）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）３５部，ＭｎＯ ５部，Ｆｅ₂Ｏ₃６０部を使用する以外は製造例１と同様にして、平均粒径３７．５μｍのフェライトキャリア芯材粒子（飽和磁化４７Ａｍ²／ｋｇ）Ｈを得た。
【０２１１】
（磁性キャリア芯材粒子の製造例９）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）０．００２部，ＭｎＯ ２５部，Ｆｅ₂Ｏ₃ ７４．９９８部を使用する以外は製造例１と同様にして、平均粒径３５．５μｍのフェライトキャリア芯材粒子（飽和磁化６３Ａｍ²／ｋｇ）Ｉを得た。
【０２１２】
（磁性キャリア芯材粒子の製造例１０）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）１０部，ＭｎＯ ８０部，Ｆｅ₂Ｏ₃ １０部を使用する以外は製造例１と同様にして、平均粒径３５．８μｍのフェライトキャリア芯材粒子（飽和磁化１５Ａｍ²／ｋｇ）Ｊを得た。
【０２１３】
（磁性キャリア芯材粒子の製造例１１）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）２５部，ＭｎＯ ０部，Ｆｅ₂Ｏ₃７５部を使用する以外は製造例１と同様にしたが、粒子合一が激しく、キャリア粒子が得られなかった。
【０２１４】
（磁性キャリア芯材粒子の製造例１２）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）２０部，ＭｎＯ ６５部，Ｆｅ₂Ｏ₃ １５部を使用する以外は製造例１と同様にして、平均粒径３６．３μｍのフェライトキャリア芯材粒子（飽和磁化２０Ａｍ²／ｋｇ）Ｋを得た。
【０２１５】
（磁性キャリア芯材粒子の製造例１３）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）３部，ＭｎＯ １部，Ｆｅ₂Ｏ₃ ９６部を使用する以外は製造例１と同様にして、平均粒径３８．５μｍのフェライトキャリア芯材粒子（飽和磁化７０Ａｍ²／ｋｇ）Ｌを得た。
【０２１６】
（キャリアの製造例１〜７）
トルエン２０部，ブタノール２０部，水２０部，氷４０部を四つ口フラスコにとり、撹拌しながらＣＨ₃ＳｉＣｌ₃ １５モルと（ＣＨ₃）₂ＳｉＣｌ₂ １０モルとの混合物４０部を加え、更に３０分間撹拌した後、６０℃で１時間縮合反応を行った。その後シロキサンを水で十分に洗浄し、トルエン−メチルエチルケトン−ブタノール混合溶媒に溶解して固型分１０％のシリコーンワニスを調製した。
【０２１７】
このシリコーンワニスにシロキサン固型分１００部に対して２．０部のイオン交換水および２．０部の下記硬化剤
【０２１８】
【化８】

と、３．０部の下記アミノシランカップリング剤
【０２１９】
【化９】

を同時添加し、キャリア被覆溶液Ｉを作製した。
【０２２０】
この被覆溶液Ｉを塗布機（岡田精工社製：スピラコータ）により、前述の磁性キャリア芯材粒子１００部Ａ〜Ｇに樹脂コート量が１．０部となるように塗布し、それぞれコーティングキャリア１〜７を得た。
【０２２１】
（キャリア製造例８）
キャリアの製造例１において用いたアミノシランカップリング剤を下記アミノシランカップリング剤
【０２２２】
【化１０】

に変えた樹脂溶液（ＩＩ）を使用することを除いては、キャリアの製造例１と同様にしてコーティングキャリア８を得た。
【０２２３】
（キャリア製造例９）
キャリア製造例１において用いたシロキサン及び硬化剤を使用しないコーティング溶液（ＩＩＩ）を使用することを除いては、キャリア製造例１と同様にしてコーティングキャリア９を得た。
【０２２４】
（キャリア製造例１０）
キャリア製造例１において用いたアノミシランカップリング剤を使用しない樹脂溶液（ＩＶ）をを使用することを除いては、キャリア製造例１と同様にしてコーティングキャリア１０を得た。
【０２２５】
（キャリア製造例１１〜１５）
キャリア製造例１〜７で用いた磁性キャリア芯材粒子Ａ〜Ｇに代えて磁性キャリア芯材粒子Ｈ〜Ｌを用いることを除いては、キャリア製造例１〜７と同様にして、コーティングキャリア１１〜１５をそれぞれ得た。
【０２２６】
表１に上記で得たキャリア１〜１５のそれぞれの物性を示す。
【０２２７】
【表１】

【０２２８】
（トナーの製造例１）
プロポキシ化ビスフェノールとフマル酸を １００部
縮合して得られたポリエステル樹脂
フタロシアニン顔料 ４部
ジ−ｔｅｒｔ−ブチルサリチル酸のクロム錯体 ４部
【０２２９】
上記原料をヘンシェルミキサーにより十分予備混合を行い、二軸押出式混練機により溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度に粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。さらに得られた微粉砕物を分級して、重量平均粒径が５．８μｍの黒色の粉体（トナー粒子）を得た。
【０２３０】
上記黒色粉体１００部と、水媒体中でｎ−Ｃ₄Ｈ₉−Ｓｉ−（ＯＣＨ₃）₃を親水性アナターゼ型酸化チタン微粉末１００部に対して２０部で処理した重量平均粒径０．０５μｍ，疎水化度５５％及び光透過率７０％を有するアナターゼ型酸化チタン微粉末１．５部とをヘンシェルミキサーで混合しシアントナーａを得た。
【０２３１】
（トナーの製造例２）
トナーの製造例１で用いたアナターゼ型酸化チタン微粉末を焼結せずに水和物のまま処理して、重量平均粒径０．０００８μｍ，疎水化度５０％及び光透過率７０％を有するチタン化合物に代えたことを除いては、トナーの製造例１と同様にしてシアントナーｂを得た。
【０２３２】
（トナーの製造例３）
トナーの製造例１で用いたアナターゼ型酸化チタン微粉末を重量平均粒径０．４μｍ，疎水化度７０％及び光透過率２０％を有する顔料用ルチル型酸化チタン２０％に代えたことを除いては、トナーの製造例１と同様にしてシアントナーｃを得た。
【０２３３】
（トナーの製造例４）
トナーの製造例１で用いたアナターゼ型酸化チタン微粉末をさらに１００ｃｐのジメチルシリコーンオイルで処理して、重量平均粒径０．０５μｍ，疎水化度６５％及び光透過率６５％を有する酸化チタン微粒子に代えたことを除いては、トナーの製造例１と同様にしてシアントナーｄを得た。
【０２３４】
（トナーの製造例５）
トナーの製造例１で用いたアナターゼ型酸化チタン微粉末を、気相中で１００ｃｐのジメチルシリコーンオイルで処理して重量平均粒径０．０２μｍ，疎水化度９０％及び光透過率３５％を有するシリカ微粒子に代えたことを除いては、トナーの製造例１と同様にしてシアントナーｅを得た。
【０２３５】
実施例１
前述のシアントナーａとキャリア１とをトナー濃度７％で混合して二成分系現像剤を作製し、図２に示した交番電界を使用したカラー複写機ＣＬＣ７００（キヤノン製）を用い、現像コントラスト３００Ｖで、画像面積比率２５％のオリジナル原稿を用いて、温度／湿度が２３℃／６５％ＲＨ下，３０℃／８０％ＲＨ下，２０℃／１０％ＲＨ下でそれぞれ１万枚の画出しをした結果を表２に示した。表２より、上述の二成分系現像剤は耐刷試験における変動も小さく、１万枚後の飛散も問題なく、非常に良好であることがわかる。
【０２３６】
実施例２
実施例１で用いたキャリア１に代えて、表１に示すキャリア２を用い、さらにトナー濃度を９％にすることを除いては実施例１と同様にして二成分系現像剤を調製し、同様に評価を行った。結果を表２に示す。
【０２３７】
参考例１
実施例１で用いたキャリア１に代えて、表１に示すキャリア３を用い、さらにトナー濃度を５％にすることを除いては実施例１と同様にして二成分系現像剤を調製し、同様に評価を行った。結果を表２に示す。
【０２３８】
実施例３〜５及び参考例２
実施例１で用いたキャリア１に代えて、表１に示すキャリア４，５，８及び１０を表２に示す通りそれぞれ使用することを除いては実施例１と同様にして二成分系現像剤を調製し、同様に評価を行った結果を表２に示す。
【０２３９】
比較例１〜３
実施例１で用いたキャリア１に代えて、表１に示すキャリア６，７及び９を表２に示す通りそれぞれ使用することを除いては実施例１と同様にして二成分系現像剤を調製し、同様に評価を行った結果を表２に示す。
【０２４０】
比較例４〜９
実施例１で用いたキャリア１に代えて、表１に示すキャリア１１〜１５を表２に示す通りそれぞれ使用することを除いては、実施例１と同様にして二成分系現像剤を調製し、同様に評価を行った結果を表２に示す。
【０２４１】
【表２】

【０２４２】
（キャリア製造例１６及び１７）
キャリアの製造例１において、イオン交換水の添加量を０部および７部に変えることを除いてはキャリアの製造例１と同様にして、コーティングキャリア１６及び１７をそれぞれ得た。
【０２４３】
実施例６
キャリア１６を使用する以外は、実施例１同様に評価を行ったところ、実用上問題ないレベルではあるが、２０℃／１０％ＲＨ下で１．５％と若干カブリが悪化し、耐久性が低下した。これは、水を使用しなかったために樹脂被覆が十分に行われなかったためと推測される。
【０２４４】
実施例７
キャリア１７を使用する以外は、実施例１同様に評価を行ったところ、実用上問題ないレベルではあるが、トナー濃度が制御範囲の上限にあるとき、３０℃／８０％ＲＨ下で若干トナー飛散が発生した。これは、水使用量が多かったために、樹脂の自己架橋が進み過ぎ、キャリア芯材表面との密着性が若干低下したためと推測される。
【０２４５】
実施例８
実施例１で用いたトナーａに代えてトナーｂを用いることを除いては、実施例１と同様にして二成分系現像剤を調製し、同様にして評価したところ、初期の画質は良好だったものの２０℃／１０％ＲＨ下でのベタの均一性がわずかに低下し、カブリも１．６％と若干悪化した。
【０２４６】
実施例９
実施例１で用いたトナーａに代えてトナーｃを用いることを除いては、実施例１と同様にして二成分系現像剤を調製し、同様にして評価したところ、３０℃／８０％ＲＨ下でトナー飛散がわずかに発生した。またカブリも１．７％と低下した。
【０２４７】
実施例１０
実施例１で用いたトナーａに代えてトナーｄを用いることを除いては、実施例１と同様にして二成分系現像剤を調製し、同様にして評価したところ、カブリは０．９％と良好になったものの、２０℃／１０％ＲＨ下でのベタの均一性が若干低下したものの良好な結果が得られた。
【０２４８】
参考例３
実施例１で用いたトナーａに代えてトナーｅを用いることを除いては、実施例１と同様にして二成分系現像剤を調製し、同様に評価したところ、２０℃／１０％ＲＨ下でベタの均一性が若干低下し、３０℃／８０％ＲＨ下でカブリが１．５％と若干悪化したものの良好な結果が得られた。
【０２４９】
実施例１１
実施例１で用いたトナーａとコーティングキャリア１とを組合わせた二成分系現像剤を用い、図１に示す画像形成装置を用いて、現像スリーブが現像主極９６０ガウスを持つ５極構成のマグネットローラーを内蔵し、図４の交番電界を重畳して、現像条件をＶ_cont＝２３０Ｖ，Ｖ_back＝−１３０Ｖに設定して、温度／湿度が２３℃／６０％ＲＨ下で画出し試験を行った。
【０２５０】
その結果１万枚耐久後でも１．０％のカブリで２０℃／１０％ＲＨ下でのベタ均一性ともに問題なく非常に良好な結果が得られた。
【０２５１】
実施例１２
実施例１１で用いた交番電界に代えて図３に示す交番電界を用いることを除いては、実施例１１と同様にして画出し試験を行った。
【０２５２】
その結果、２０℃／１０％ＲＨ下でのベタの均一性が若干低下し、カブリが１．４％と若干低下したものの良好な結果が得られた。
【０２５３】
実施例１３
実施例１１で用いた交番電界に代えて図５に示す交番電界を用いることを除いては、実施例１１と同様にして画出し試験を行った。
【０２５４】
その結果、２０℃／１０％ＲＨ下のベタ均一性が若干低下したものの良好な結果が得られた。
【０２５５】
（磁性キャリア芯材粒子の製造例１４）
ＭｇＯ（溶解度０．６２ｍｇ／１００ｍｌ）２０部，ＭｎＯ ２０部，Ｆｅ₂Ｏ₃ ６０部をそれぞれ微粒化した後、水を添加混合し造粒した後、１１００℃にて焼成し表３に示すような粒度調整をした後、平均粒径３５．７μｍのフェライトキャリア芯材粒子（飽和磁化５８Ａｍ²／ｋｇ）Ｍを得た。
【０２５６】
（磁性キャリア芯材粒子の製造例１５）
ＭｇＯ １５部，ＭｎＯ １５部，ＳｉＯ₂ ３部，Ｆｅ₂Ｏ₃ ６７部を使用し、１３００℃で焼成する以外は製造例１６と同様にして、平均粒径３８．３μｍのフェライトキャリア芯材粒子（飽和磁化６０Ａｍ²／ｋｇ）Ｎを得た。
【０２５７】
（磁性キャリア芯材粒子の製造例１６）
ＭｇＯ ３部，Ｌｉ₂Ｏ ５部，Ｆｅ₂Ｏ₃ ９２部を使用する以外は製造例１５と同様にして、平均粒径４０．５μｍのフェライトキャリア芯材粒子（飽和磁化５７Ａｍ²／ｋｇ）Ｏを得た。
【０２５８】
（磁性キャリア芯材粒子の製造例１７）
ＭｇＯ ２０部，Ａｌ₂Ｏ₃ ５部，Ｆｅ₂Ｏ₃ ７５部を使用する以外は製造例１６と同様にして、平均粒径４３．２μｍのフェライトキャリア芯材粒子（飽和磁化５７Ａｍ²／ｋｇ）Ｐを得た。
【０２５９】
（キャリアの製造例１８〜２１）
キャリアの製造例１〜７で用いた磁性キャリア芯材粒子Ａ〜Ｇに代えて磁性キャリア芯材粒子Ｍ〜Ｐを用い、さらに被覆溶液Ｉの樹脂コート量を０．５重量％に変更することを除いては、キャリアの製造例１〜７と同様にしてコーティングキャリア１８〜２１をそれぞれ得た。
【０２６０】
（キャリアの製造例２２）
スチレン−２エチルヘキシルアクリレート−メチルメタクリレート（５０：２０：３０）共重合体５０部およびフッ化ビニリデン−４フッ化エチレン（５０：５０）共重合体５０部を混合して、トルエン−メチルエチルケトン混合溶媒に溶解して、調製した被覆溶液Ｖを塗布する以外は、キャリアの製造例１６〜１９と同様にしてコーティングキャリア２２を得た。
【０２６１】
表３に上記で得たキャリア１８〜２２のそれぞれの物性を示す。
【０２６２】
【表３】

【０２６３】
（ポリエステル樹脂合成例１）
ポリオキシプロピレン（２．２）−２，２ビス ４５ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
ポリオキシエチレン（２）−２，２−ビス ６ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
フマール酸 ４７ｍｏｌ％
無水トリメリット酸 ２ｍｏｌ％
【０２６４】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点９２℃に達したときに反応を終了させ、ポリエステル樹脂（Ｉ）を得た。
【０２６５】
該樹脂の酸価は９．５ＫＯＨｍｇ／ｇ，ガラス転移温度は５７．２℃であった。
【０２６６】
（ポリエステル樹脂合成例２）
ポリオキシプロピレン（２．２）−２，２ビス ４５ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
ポリオキシエチレン（２）−２，２−ビス ４ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
フマール酸 ４０ｍｏｌ％
テレフタル酸 １０ｍｏｌ％
無水トリメリット酸 １ｍｏｌ％
【０２６７】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点９１℃に達したときに反応を終了させ、ポリエステル樹脂（ＩＩ）を得た。
【０２６８】
該樹脂の酸価は２２．０ＫＯＨｍｇ／ｇ，ガラス転移温度は５５．３℃であった。
【０２６９】
（ポリエステル樹脂合成例３）
ポリオキシプロピレン（２．２）−２，２ビス ４５ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
ポリオキシエチレン（２）−２，２−ビス １０ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
フマール酸 ４３ｍｏｌ％
１，２，５−ヘキサントリカルボン酸 ２ｍｏｌ％
【０２７０】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点９５℃に達したときに反応を終了させ、ポリエステル樹脂（ＩＩＩ）を得た。
【０２７１】
該樹脂の酸価は０．８ＫＯＨｍｇ／ｇ，ガラス転移温度は５８．１℃であった。
【０２７２】
（ポリエステル樹脂合成例４）
ポリオキシプロピレン（２．２）−２，２ビス ４９ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
テレフタル酸 ４９ｍｏｌ％
２，５，７−ナフタレントリカルボン酸 ２ｍｏｌ％
【０２７３】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点９２℃に達したときに反応を終了させ、ポリエステル樹脂（ＩＶ）を得た。
【０２７４】
該樹脂の酸価は１７．１ＫＯＨｍｇ／ｇ，ガラス転移温度は５７℃であった。
【０２７５】
（ポリエステル樹脂合成例５）
ポリオキシプロピレン（２．２）−２，２ビス ５３ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
フマール酸 ４５ｍｏｌ％
１，２，７，８−オクタンテトラカルボン酸 ２ｍｏｌ％
【０２７６】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点９５℃に達したときに反応を終了させ、ポリエステル樹脂（Ｖ）を得た。
【０２７７】
該樹脂の酸価は２．２ＫＯＨｍｇ／ｇ，ガラス転移温度は５９℃であった。
【０２７８】
（ポリエステル樹脂合成例６）
ポリオキシプロピレン（２．２）−２，２ビス ５０ｍｏｌ％
（４−ヒドロキシフェニル）プロパン
テレフタル酸 ４９．５ｍｏｌ％
無水トリメリット酸 ０．５ｍｏｌ％
【０２７９】
上記原料にジブチル錫オキサイドを触媒として加え、窒素気流下にて２００℃にて縮重合反応を行い、ＡＳＴＭ Ｅ２８−５１Ｔに準ずる軟化点１０３℃に達したときに反応を終了させ、ポリエステル樹脂（ＶＩ）を得た。
【０２８０】
該樹脂の酸価は８．７ＫＯＨｍｇ／ｇ，ガラス転移温度は６１℃であった。
【０２８１】
（トナーの製造例７）
プロポキシ化ビスフェノールとフマル酸およびトリメリット酸 １００部
トリメリット酸を縮合して得られたポリエステル樹脂（Ｉ）
フタロシアニン顔料 ４部
ジ−ｔｅｒｔ−ブチルサリチル酸の金属錯体 ４部
【０２８２】
上記をヘンシェルミキサーにより十分予備混合を行い、二軸押出式混練機により溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度に粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。さらに得られた微粉砕物を分級して、重量平均粒径が５．８μｍである青色の粉体を得た。
【０２８３】
上記着色粉体１００部と水／ブタノール混合媒体中でｉｓｏ−Ｃ₄Ｈ₉−Ｓｉ−（ＯＣＨ₃）₃を２０部で処理したアルミナ微粉末平均粒径０．０２μｍ，疎水化度６５％１．５部とをヘンシェルミキサーで混合しシアントナーｆを得た。
【０２８４】
このトナーの酸価は、９．５ＫＯＨｍｇ／ｇ、Ｔｍは９０℃及びＴｇは５５℃であった。
【０２８５】
（トナーの製造例８）
トナーの製造例７において、アルミナのかわりに、水媒体中で、ｎ−Ｃ₄Ｈ₉−Ｓｉ−（ＯＣＨ₃）₃を２５部で処理した酸化チタン微粉末（平均粒径０．０３μｍ，疎水化度６０％）を使用する以外はトナーの製造例７と同様にしてシアントナーｇを得た。
【０２８６】
このトナーの酸価，Ｔｍ及びＴｇはトナーｆと同じであった。
【０２８７】
（トナーの製造例９〜１３）
トナーの製造例７において用いたポリエステル樹脂（Ｉ）に代えて、ポリエステル樹脂（ＩＩ）〜（ＶＩ）を使用する以外は同様にして表４に示すトナーｈ〜ｌを得た。
【０２８８】
上記で得られたトナーｆ〜ｌの構成及び物性を表４に示す。
【０２８９】
【表４】

【０２９０】
実施例１４及び１５
前述のシアントナーｆ及びｇとキャリア１８とをトナー濃度７％で混合して二成分系現像剤を作製し、カラー複写機ＣＬＣ７００（キヤノン製）を用い、静電潜像保持体の保護層中のフッ素原子含有樹脂粒子３０重量％を含有する静電潜像保持体（Ｉ）、および交番電界として図４に示す非連続の電界を印加し、現像コントラスト３００Ｖで、画像面積比率２５％のオリジナル原稿を用いて、２３℃／６５％ＲＨ下，３０℃／８０％ＲＨ下，２０℃／１０％ＲＨ下で１万枚の画出しをした結果を表５に示した。
【０２９１】
実施例１６〜１９
実施例１４及び１５で用いたシアントナーｆ及びｇに代えて、シアントナーｈ〜ｋを使用する以外は、実施例１４及び１５と同様にして画出しを行った結果を表５に示した。酸価が高いトナーｈ及び酸価が低いトナーｊを用いた実施例１６及び１７は、実施例１４及び１５に比べてトナー飛散が若干悪化したが、実用上問題のないレベルであった。
【０２９２】
実施例２０
実施例１４及び１５で用いたトナーｆ及びｇに代えてトナーｌを使用する以外は実施例１４及び１５と同様に行ったところ、画像光沢が低下し、画像濃度が若干低くなったものの表５に示す通り良好な結果が得られた。
【０２９３】
実施例２１〜２３
実施例１４及び１５で用いたキャリア１８に代えてキャリア１９〜２１を使用する以外は、実施例１４及び１５と同様に画出しを行ったところ、表５に示す通り良好な結果が得られた。
【０２９４】
参考例４
実施例１４及び１５で用いたキャリア１８に代えて、キャリア２２を使用する以外は、実施例１４及び１５と同様に画出しを行ったところ、コート材がシリコーン系レジンでないため、若干耐久性が低下したが、表５に示す通り良好な結果が得られた。
【０２９５】
実施例２４〜２６
実施例１４及び１５で用いた静電潜像保持体（Ｉ）に代えて静電潜像保持体の保護層中のフッ素原子含有樹脂粒子の含有量をそれぞれ２０％，６％及び０％に変更した静電潜像保持体（ＩＩ）〜（ＩＶ）を使用する以外は実施例１４及び１５と同様に行った結果を表５に示す。フッ素原子含有樹脂粒子含有量が減るに従って、ベタ均一性が若干悪化するが、実用上まったく問題はなかった。
【０２９６】
実施例２７及び２８
実施例１４及び１５で用いた交番電界に代えて、図５及び図２に示す交番電界をそれぞれ使用する以外は実施例１４及び１５と同様に行ったところ、表５に示す通り良好な結果が得られた。
【０２９７】
実施例２９
実施例１４及び１５で用いた交番電界に代えて、交番電界として、図３に示す連続電界を使用する以外は、実施例１４及び１５と同様に行ったところ、画像濃度が若干低下し、ベタ均一性も若干悪化したが、表５に示す通り実用上問題ないレベルであった。
【０２９８】
【表５】

【０２９９】
上記実施例において、画像濃度，カブリ，耐久性（トナースペント），トナー飛散及びベタ均一性は、以下の評価方法に基づいて評価した。
【０３００】
［画像濃度］
濃度は反射濃度計ＲＤ９１８（マクベス社製）で測定した。
【０３０１】
◎：優 １．６〜１．７
○：良 １．７超〜１．８、１．４５〜１．６未満
△：可 １．８超〜１．９、１．３〜１．４５未満
×：不可 １．９超、１．３未満
【０３０２】
［カブリ］
カブリの評価は、東京電色社製のＲＥＦＬＥＣＴＯＭＥＴＥＲ ＭＯＤＥＬ
ＴＣ−６ＤＳを使用して測定し、シアントナー画像ではａｍｂｅｒフィルターを使用し、下記式より算出した。数値が小さい程、カブリが少ない。
【０３０３】
カブリ（反射率）（％）＝標準紙の反射率（％）−サンプルの非画像部の反射率（％）
【０３０４】
◎：０〜１．２％
○：１．２％超〜１．６％
△：１．６％超〜１．９％
×：１．９％超
【０３０５】
［トナースペント］
走査型電子顕微鏡で、２，０００倍で観察する。
【０３０６】
◎ トナースペントが認められず、帯電量も下がっていない。
○ ややトナースペントが認められるが、帯電量は下がっていない。
△ 凹部にトナースペントが多く認められるが、帯電量変化は小さい。
× 全体にトナースペントが認められ、帯電量変化が大きい。
【０３０７】
［トナー飛散］
トナー飛散は、現像容器の上流側トナー飛散抑制部及び下流側トナー飛散抑制部の外表面のトナーによる汚れ、及び現像容器以外のトナーによる汚れを観察し下記評価基準に基づいて評価した。
【０３０８】
◎ 全く認められない。
○ 現像容器の上流側トナー飛散抑制部外表面に汚れが若干認められるが、下流側トナー飛散抑制部外表面には汚れが認められない。
△ 現像容器の上流側トナー飛散抑制部の外表面及び下流側トナー飛散防止部の外表面には汚れが認められるが、現像容器以外には汚れが認められない。
× 現像容器以外まで汚れが認められる。
【０３０９】
［ベタ均一性］
◎ ＣＬＣ−ＳＫ紙で、１週間放置紙でまったく問題ない。
○ ＣＬＣ−ＳＫ紙で、３日間放置紙で問題ない。
△ ＣＬＣ−ＳＫ紙で、１晩放置紙で問題ない。
× ＣＬＣ−ＳＫ紙で、１晩放置紙でムラが有る。
【０３１０】
【発明の効果】
本発明のキャリア及び該キャリアを用いた二成分系現像剤においては、キャリアは特定のフェライト成分で形成された磁性キャリア芯材粒子表面を樹脂被覆層被覆したことにより、大画像面積のカラー原稿の連続複写を行っても画像濃度の低下及びカブリが生じ難く、トナーとキャリアの摩擦帯電のすみやかな立上がりが得られ、かつカブリのない鮮明な画像を多数枚耐久後まで維持することが可能であり、摩擦帯電特性の環境依存性が少なく、さらに現像器内での搬送性が良好であるという効果を有している。
【図面の簡単な説明】
【図１】本発明の画像形成方法に用いられる画像形成装置の概略図を示す。
【図２】実施例１で用いる交番電界を示す図である。
【図３】実施例１２で用いる交番電界を示す図である。
【図４】実施例１１で用いる交番電界を示す図である。
【図５】実施例１３で用いる交番電界を示す図である。
【図６】本発明の画像形成方法に用いることが可能な静電潜像保持体の好ましい形態を示す図である。
【図７】本発明の画像形成方法に用いられる画像形成装置の他の例を示す図である。[0001]
[Industrial application fields]
The present invention relates to a two-component developer used for developing an electrical latent image in an electrophotographic method or an electrostatic printing method, and more particularly to a two-component developer having significantly improved durability, image quality, and environmental characteristics, and The present invention relates to an image forming method using the two-component developer.
[0002]
[Prior art]
Carriers constituting the two-component developer are roughly classified into conductive carriers and insulating carriers, and oxidized or unoxidized iron powder is usually used as the conductive carrier. In the two-component developer containing the iron powder carrier as a component, there is a problem that the triboelectric chargeability with respect to the toner is unstable, and fogging is likely to occur in the formed visible image. That is, with the use of a two-component developer, toner particles adhere to and accumulate on the surface of the iron powder carrier particles (spent toner), so the electric resistance of the iron powder carrier particles increases and the bias current decreases. In addition, the triboelectric chargeability becomes unstable, and as a result, the image density of the visible image formed decreases and fogging increases. Therefore, if two-component developer containing iron powder carrier is used for continuous copying with an electronic copying machine, the two-component developer deteriorates with a small number of copies. It is necessary to replace it, and the cost becomes high after all.
[0003]
Insulative carriers are typically carriers in which the surface of a carrier core made of a ferromagnetic material such as iron, nickel, or ferrite is uniformly coated with an insulating resin. In the two-component developer using the insulating carrier, the toner particles are significantly less fused to the carrier surface than in the case of the conductive carrier, and at the same time, the triboelectric charging property between the toner and the carrier can be controlled. There is an advantage that it is suitable for a high-speed electrophotographic copying machine in that it is easy, has excellent durability and has a long service life.
[0004]
There are various characteristics required for insulating carriers, but especially important characteristics are appropriate charging, impact resistance, wear resistance, good adhesion between core and coating material, uniformity of charge distribution, etc. Can be mentioned.
[0005]
In view of the above required characteristics, the insulating carriers that have been used in the past still have problems to be improved, and the complete one is not known at present. For example, those using an acrylic resin as a coating material for a carrier are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 47-13954 and 60-208765. In particular, the molecular weight is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-208767. In this publication, the chargeability of the coated carrier is stabilized by maintaining the molecular weight constant. It has been known. However, in order to attach the coating resin to the carrier core material, it is easily affected by the conditions of the device and the environment in which the coating is performed, especially humidity, even if they are strictly controlled, the resin is stably attached to the core material, In order to provide sufficient chargeability and durability, there is still nothing satisfactory.
[0006]
On the other hand, a proposal has been made to improve durability by using a resin having a low surface energy as a coating layer in order to prevent the carrier from becoming spent such as toner fusion, and examples of the resin having a low surface energy include a silicone resin.
[0007]
Silicone resins have the advantage of high water repellency in addition to low surface energy and surface tension. On the other hand, since silicone resin has low adhesiveness, it has a problem that it is easily peeled off when used for a coating layer.
[0008]
In order to improve this problem, for example, a method using a resin-modified silicone resin (Japanese Patent Laid-Open No. 55-127469), a method of containing vinylsilane and reacting with another resin (Japanese Patent Laid-Open No. 56-32149), A method using a mixture of trialkoxysilane and ethyl cellulose (USP 3,840,464) and a method using a mixture of an organosilicone terpolymer and a polyphenylene resin (USP 3,849,127) have been proposed. However, a high temperature of 300 ° C. or higher is necessary for the formation of the coating film, or the compatibility between the silicone resin and other resins is low and the coating film becomes non-uniform so that the expected characteristics cannot be obtained. There was a problem to say.
[0009]
It has also been proposed to form a coating film at a relatively low curing temperature (Japanese Patent Laid-Open No. 55-127469), but the adhesiveness is insufficient and the toughness of the coating film is insufficient. If the carrier particles collide with the inner wall of the developing unit or the surface of the photosensitive member due to strong long-time stirring in the developing unit such as a high-speed copying machine, or the particles collide with each other, the silicone resin coating layer is easily worn. Peeling off due to wear or damage over time, and the frictional charge changes from charging between the toner and silicone resin to charging the toner and the carrier core material, so the charge amount of the toner is not kept constant and image quality deteriorates It was what brought about.
[0010]
Furthermore, in recent years, demands for high definition and high image quality of copying machines have increased in the market, and in this technical field, attempts have been made to achieve high image quality color by reducing the particle size of toner. As the particle size becomes smaller, the surface area per unit weight increases and the charge amount of the toner tends to increase, and the charging speed tends to slow, and there is a concern about durability deterioration such as low image density, fogging, and toner scattering. It is a place.
[0011]
That is, in developing the electrostatic latent image held on the electrostatic latent image holding member, the toner is mixed with a carrier having relatively large particles and used as a two-component developer for electrophotography. The composition of both the toner and the carrier is selected so that, for example, the toner has a polarity opposite to the charge on the photoconductive layer due to mutual contact friction. As a result of the contact friction between the two, the carrier electrostatically adheres the toner to the surface, transports the developer as a developer, and supplies the toner onto the photoconductive layer of the electrostatic latent image holding member.
[0012]
However, when such a two-component developer is used to continuously copy a large number of sheets with an electronic copying apparatus, a clear and good image can be obtained in the beginning. Thus, the image has poor gradation and sharpness with a remarkable edge effect.
[0013]
In color copying using chromatic toner, continuous tone is an important factor that affects image quality, and the edge effect that emphasizes only the periphery of the image after copying a large number of sheets results in the tone of the image. Is greatly impaired. For example, a pseudo contour due to the edge effect is formed in the vicinity of the actual contour.
[0014]
Furthermore, the image area used in the conventional black-and-white copy is 10% or less, and the image is almost a line image portion like a letter, a document, or a report. The area is at least 20% or more, and solid images with gradation such as photographs, catalogs, maps, and paintings occupy a considerable frequency or area.
[0015]
When such continuous copying is performed using a document having a large image area, a copy with a high image density is usually obtained in the initial stage. However, the toner supply to the two-component developer is not in time, and the density decreases. In this state, the replenished toner and the carrier are mixed in a state where charging is insufficient, causing fogging, and a partial increase or decrease in toner density (indicating the mixing ratio of toner and carrier) on the developing sleeve. There is a tendency that image blur and uniformity of image density cannot be obtained. This tendency is more remarkable when the diameter of the toner is reduced.
[0016]
This is because the toner inclusion amount (that is, the toner concentration) in the two-component developer is too low, or the rapid frictional charge rise between the replenishment toner and the carrier in the two-component developer is poor, and it is uncontrollable. Such insufficient development and fogging may occur due to insufficiently charged toner involved in development.
[0017]
As a color developer, the ability to always output a high-quality image by continuous copying of a document having a large image area is essential. Conventionally, in order to cope with a document having a large image area and a large amount of toner consumption, the development apparatus has been improved more than the development of the developer itself. That is, in order to increase the chance of contact of the developing sleeve with the electrostatic latent image, the peripheral speed of the developing sleeve is increased, or the developing sleeve has a large diameter.
[0018]
Although these measures increase the developing capability, contamination of the inside of the apparatus due to toner scattering from the developing device, and the life of the device being significantly limited due to overloading to the developing device drive, etc. occur. Furthermore, there are cases where a large amount of developer is introduced into the developing device to make up for the lack of developer development capacity. However, these also increase the weight of the entire device and increase the cost of the device. As described above, this results in an overload on the driving of the developing device and is not preferable.
[0019]
Therefore, improvement studies from both toner and carrier have been reported for the purpose of maintaining high image quality over a long period of time.
[0020]
Heretofore, several developers have been proposed for the purpose of improving image quality. For example, Japanese Patent Application Laid-Open No. 51-3244 proposes a non-magnetic toner intended to improve the image quality by regulating the particle size distribution. The toner is mainly composed of a toner having a particle size of 8 to 12 μm, and is relatively coarse. According to the study by the present inventors, it is difficult to make a uniform “paste” to the latent image. In addition, from the characteristic that 5 μm or less is 30% by number or less and 20 μm or more is 5% by number or less, the point that the particle size distribution is broad also tends to lower the uniformity. In order to form a clear image using toner having such coarse toner particles and a broad particle size distribution, the toner particles are overlapped to fill the gaps between the toner particles. There is also a problem that it is necessary to increase the image density, and the amount of toner consumption necessary to obtain a predetermined image density increases.
[0021]
Japanese Patent Application Laid-Open No. 54-72054 proposes a nonmagnetic toner having a sharper distribution than the former, but the particle size of the intermediate weight is as coarse as 8.5 to 11.0 μm, and high resolution is achieved. As a sex toner, there is still room for improvement.
[0022]
JP-A-58-129437 proposes a non-magnetic toner having an average particle diameter of 6 to 10 μm and a most frequent particle of 5 to 8 μm. There is a tendency that an image lacking sharpness is formed.
[0023]
According to the study by the present inventors, it has been found that toner particles having a size of 5 μm or less clearly reproduce the outline of the latent image and have a main function of dense toner paste onto the entire latent image. Particularly, in the electrostatic charge latent image on the photosensitive member, the electric field lines are concentrated, so that the electric field strength is higher in the edge portion that is the contour than in the inside, and the sharpness of the image quality is determined by the quality of the toner particles collected in this portion. According to the study by the present inventors, it has been found that the amount of particles of 5 μm or less is effective in solving the problem of sharpness of image quality.
[0024]
In view of this, the present inventors have proposed a toner containing 15 to 40% by number of toner particles having a size of 5 μm or less in Japanese Patent Laid-Open No. Hei 2-222966. High image quality is also desired.
[0025]
Japanese Patent Laid-Open No. 2-877 proposes a toner containing 17 to 60% by number of toner particles of 5 μm or less. This ensures that the image quality and image density are stable, but is consumed like a photographic original. It has also been found that when a large amount of originals are printed continuously, the toner particle size distribution changes only by measures as a toner, and it is difficult to always obtain a constant image.
[0026]
On the other hand, there are JP-A 51-3238, JP-A 58-144839 and JP-A 61-204646 which suggest the average particle size and particle size distribution of the carrier. Japanese Patent Application Laid-Open No. 51-3238 refers to a rough particle size distribution. However, magnetic properties that are closely related to the developability of the developer and the transportability in the developing device are not specifically disclosed. Furthermore, regarding the particle size of the carrier, all the carriers in the examples are about 80% by weight or more of 250 mesh or more, and the average particle size is also 60 μm or more.
[0027]
Japanese Laid-Open Patent Publication No. 58-144839 merely discloses the average particle diameter of the carrier and refers to the amount of fine powder that affects carrier adhesion to the photoreceptor and the amount of coarse powder that affects the sharpness of the image. However, the distribution is not described in detail in consideration of the characteristics of color copying.
[0028]
Japanese Patent Application Laid-Open No. 61-204646 uses a combination of a copying machine and an appropriate developer as the gist of the invention, and does not specifically describe the particle size distribution or magnetic characteristics of the carrier. Furthermore, there is no disclosure of why the developer is effective in the copying apparatus.
[0029]
Japanese Patent Application Laid-Open No. 49-70630 describes the magnetic force of a carrier, which is an iron powder having a specific gravity larger than that of ferrite as a carrier material and has a high saturation magnetism. Many iron powder carriers have been used in the past. However, since the specific gravity is large, the weight of the copying apparatus and the overload of the driving torque are likely to occur, and the environment dependency is also large.
[0030]
The ferrite carrier described in Japanese Patent Application Laid-Open No. 58-23032 is for a material having a lot of porous pores, and such a carrier is likely to cause an edge effect and has poor durability. It has been found to be unsuitable as a color carrier.
[0031]
Until now, there has been a demand for a developer capable of continuously copying an image having a large image area with a small amount of developer and satisfying the characteristic characteristic of color copying that does not produce an edge effect even after durability. The developer and carrier have been studied, but most of them have been proposed in consideration of black-and-white copying, and very few have been proposed as being applicable to full-color copying. Furthermore, there is a carrier having the ability to continue copying an image having an image area of 20% or more which is almost a solid image, the reduction of the edge effect, and the ability to maintain the uniformity of the image density in one copy. Long-awaited.
[0032]
Japanese Patent Laid-Open No. 2-281280 proposes a carrier having a narrow particle size distribution in which the abundance of fine powder and the abundance of coarse powder are controlled to achieve a carrier with improved development characteristics.
[0033]
However, as described above, the demand for high definition and high image quality of copiers is increasing in the market, and in this technical field, attempts have been made to achieve high image quality color by reducing the particle size of toner. However, as the particle size of the toner becomes finer, the surface area per unit weight tends to increase, and the amount of electric charge of the toner tends to increase, and there is a concern that the image density is low and durability is deteriorated.
[0034]
As described above, attempts have been made to further reduce the diameter of the carrier for the purpose of reducing the image density and preventing the deterioration of durability due to the finer toner particle diameter or improving the development efficiency. However, such a carrier does not have sufficient quality to cope with changes in the charge amount due to the environment or durability of the toner, and has all of high image density, high image quality, good anti-fogging and prevention of carrier adhesion. The reality is that it is difficult to achieve.
[0035]
[Problems to be solved by the invention]
An object of the present invention is to provide a two-component developer that solves the above-described problems and an image forming method using the two-component developer.
[0036]
That is, an object of the present invention is to provide a two-component developer that does not cause reduction in image density and blur even when a color original having a large image area is continuously copied, and an image forming method using the two-component developer. There is to do.
[0037]
A further object of the present invention is to provide a two-component developer having clear image characteristics free from fog and having excellent durability stability, and an image forming method using the two-component developer.
[0038]
Another object of the present invention is to provide a two-component developer capable of obtaining a rapid rise in frictional charging between a toner and a carrier, and an image forming method using the two-component developer.
[0039]
Another object of the present invention is to provide a two-component developer that is less dependent on the environment of frictional charging and an image forming method using the two-component developer.
[0040]
Another object of the present invention is to provide a two-component developer having good transportability in a developing device and an image forming method using the two-component developer.
[0042]
[Means and Actions for Solving the Problems]
  The present invention relates to a toner comprising at least toner particles and hydrophobized alumina microparticles or hydrophobized titanium oxide microparticles, and a magnetic carrier core particle and a resin coating layer covering the magnetic carrier core particle In a two-component developer having a carrier having
  The carrier core particles are represented by the following formula (I)
          (Fe₂O_Three)_x(A)_y(B)_z                    Formula (I)
  [In the formula, A is MgO, Ag.₂O or a mixture thereof, B represents Li₂O, MnO, CaO, SrO, Al₂O_Three, SiO₂Or a mixture thereof, x, y and z represent a weight ratio and the following conditions
  0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3,
  0 <z ≦ 0.795,x + y <1, z = 1-xy
Satisfied. ]
It is formed with a magnetic ferrite component indicated by
  The resin coating layer is an aminosilane coupling agent.And a curing agent represented by the following formula (III):A resin coating layer formed from a reactive silicone resin containing
  The carrier has a specific surface area S calculated by the air permeation method.₁And the specific surface area S calculated from the following formula (II)₂
          S₂= [6 / (ρ · D₅₀)] × 10^Four              Formula (II)
  [Wherein ρ represents the density of carriers, and D₅₀Indicates 50% particle size of the carrier. ]
Ratio to (S₁/ S₂) Is 1.3 to 1.8. A two-component developer is provided.
[0043]
  Further, the present invention provides a two-component developer having a toner and a carrier in a circulating manner by a developer carrier, and applies a developing bias having a discontinuous AC component to the developer carrier, thereby providing an electrostatic latent. An electrostatic latent image held on the electrostatic latent image carrier by forming a developing electric field in a development region between the image carrier and the developer carrier is carried on the developer carrier. An image forming method for developing with a two-component developer toner,
  The toner includes at least toner particles and hydrophobized alumina fine particles or hydrophobized titanium oxide fine particles,
  The carrier has carrier core particles and a resin coating layer covering the carrier core particles.
  The carrier core particles are represented by the following formula (I)
          (Fe₂O_Three)_x(A)_y(B)_z                    Formula (I)
  [In the formula, A is MgO, Ag.₂O or a mixture thereof, B represents Li₂O, MnO, CaO, SrO, Al₂O_Three, SiO₂Or a mixture thereof, x, y and z represent a weight ratio and the following conditions
  0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3,
  0 <z ≦ 0.795,x + y <1, z = 1-xy
Satisfied. ]
It is formed with a magnetic ferrite component indicated by
  The resin coating layer is an aminosilane coupling agent.And a curing agent represented by the following formula (III):A resin coating layer formed from a reactive silicone resin containing
  The carrier has a specific surface area S calculated by the air permeation method.₁And the specific surface area S calculated from the following formula (II)₂
          S₂= [6 / (ρ · D₅₀)] × 10^Four              Formula (II)
  [Wherein ρ represents the density of carriers, and D₅₀Indicates 50% particle size of the carrier. ]
Ratio to (S₁/ S₂) Is 1.3 to 1.8. An image forming method is provided.
[0044]
In the above formula (I), more preferably, x, y and z are the following conditions:
0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3,
x + y <1, z = 1-xy
It is preferable that the carrier core particles have an appropriate surface irregularity and have an appropriate water content, in terms of compatibility of resin adhesion and toughness. For the purpose of adjusting the crystal grain size of the surface of the magnetic carrier core particles with other metal elements in a range of 3% by weight or less that does not interfere with the effect of the ferrite component, for the purpose of preventing coalescence during firing, or the particle size distribution As a regulator, the magnetic ferrite component may be contained in the form of hydroxide, oxide, sulfide, fatty acid compound or the like.
[0045]
In the present invention, the case of x + y + z <1 in the formula (I) means that the above-mentioned optional other components are preferably contained in a range of up to 3% by weight. This will be described in Example 4 described later.
[0046]
In the above formula (I), when x is less than 0.2, the magnetic properties are low, and carrier scattering and scratches on the surface of the photosensitive member are likely to occur. When x exceeds 0.95, Core resistance tends to be low. When y is less than 0.005, it is difficult to obtain appropriate resistance and magnetic characteristics. When y exceeds 0.3, homogenization and spheroidization may not be achieved on the surface of carrier particles. When z is 0, that is, when (B) is not included, it is difficult to obtain a product with a sharp particle size distribution, and the surface of the photoconductor is damaged by the ultrafine powder of the carrier or unification at the time of baking is difficult. Become. When z exceeds 0.795, the magnetic properties are lowered and carrier scattering is deteriorated.
[0047]
In the above formula (I), it is more preferable that x, y and z satisfy the following conditions.
[0048]
0.4 ≦ x ≦ 0.9, 0.01 ≦ y ≦ 0.25,
0.01 ≦ z ≦ 0.2, x + y + z ≦ 1
[0049]
Furthermore, B in the above formula (I) of the magnetic ferrite component used in the present invention is Li₂O, MnO, CaO, SrO, Al₂O_Three, SiO₂Among them, MnO, CaO, and SiO are low in resistance drop even when a high voltage is applied.₂And Al₂O_ThreeIn particular, MnO and CaO are more preferable from the viewpoint of compatibility with the replenishing toner.
[0050]
Furthermore, a reactive silicone resin containing a specific curing agent is used as the resin used for the resin coating layer covering the surface of the magnetic carrier core particles formed of the ferrite component represented by the above formula (I). Is preferred.
[0051]
In order to improve the adhesion of magnetic carrier core particles, it has been proposed to use modified silicone resins, such as alkyd modification, epoxy modification, acrylic modification, polyester modification, phenol modification, melamine modification, and urethane modification. Although there is an example using such a modified silicone resin, the toner is easily fixed due to an increase in surface energy, which is not always satisfactory in terms of the durability of the developer.
[0052]
In order to improve the adhesiveness while maintaining a low surface energy, a method of using various additives in combination has been proposed (Japanese Patent Laid-Open No. 2-333159).
[0053]
These additives impart toughness in addition to the adhesive by reaction with the silicone resin or itself. However, what is disclosed in Japanese Patent Application Laid-Open No. 2-33159 is certainly improved in resistance as a coating resin, but it is not always necessary to form a thin coating layer on the surface of the carrier core material. The adhesion between the material and the coating resin is not satisfactory, and further improvements are desired.
[0054]
Therefore, as a result of intensive studies by the present inventors, the magnetic carrier core material particles contain 0.5 to 10 mg / 100 ml, preferably 0.5 to 2 mg / 100 ml of metal oxide having a solubility in water at 25 ° C. For the resin coating layer, a reactive silicone resin, preferably a curing agent represented by the general formula (III) described later, and more preferably a reactive silicone resin containing an aminosilane coupling agent is used on the magnetic carrier core particles. When this occurs, the appropriate moisture contained in the magnetic carrier core particles reacts with the remaining reactive groups in the silicone resin to achieve good adhesion and chargeability, resulting in a very high performance long-life carrier. It was found that can be obtained.
[0055]
Japanese Patent Application Laid-Open No. 2-333159 also describes that it contains the general formula (III) described later, but in the present invention, a metal oxide having a specific solubility is specified in the magnetic carrier core particles. The carrier is characterized in that it is contained in an amount and reacted with a reactive silicone resin, and as a result, a carrier with improved strength of the magnetic carrier core material particles and the resin coating layer is obtained. Are different.
[0056]
The magnetic carrier core particles suitably used in the present invention include MgO having a solubility of 0.62 mg / 100 ml, Ag having a solubility of 1.74 mg / 100 ml.₂Ferrite particles containing O, more preferably, ferrite containing at least 0.5 to 30% by weight of MgO in terms of oxide in terms of resistance stability of the core material is easy to homogenize and spheroidize on the surface. It is preferable because it contains moderate moisture.
[0057]
Furthermore, it is also one feature that the carrier coated with the resin coating layer of the present invention has a specific surface property and particle size distribution.
[0058]
That is, as a result of intensive studies on the image density, highlight reproducibility, and fine line reproducibility of the two-component developer, the present inventors have found that when a carrier having a specific particle size distribution and surface property is used, a high image density, They found that excellent image quality can be achieved by highlight reproduction and fine line reproduction.
[0059]
The carrier preferably used in the present invention is a carrier having a small average particle diameter, a uniform small particle diameter in which fine particles and coarse powder are controlled, and a certain degree of irregularities on the surface thereof. It is. Therefore, even if a resin having a small free energy is coated, the toner transportability is good, and the rise of the triboelectric charging property with the toner is preferably improved.
[0060]
As the carrier, the carrier has a 50% particle size (median diameter) of 15 to 60 μm, preferably 20 to 45 μm, and carrier particles smaller than 22 μm are 1 to 20% by weight, preferably 2 to 15% by weight, more preferably. Is contained in an amount of 4 to 12 wt%, and carrier particles smaller than 16 μm are contained in an amount of 0.01 to 3 wt%, preferably 0.01 to 2 wt%, more preferably 0.01 to 1 wt%. Is good. In the present invention, the 50% particle size means a particle size having a volume-based median cumulative value (50%).
[0061]
When the content of fine powder exceeds the upper limit of the above range, the resin cannot be stably coated, carrier adhesion occurs, smooth charging with the toner is prevented, and carrier particles smaller than 22 μm are less than 1% by weight, The magnetic brush becomes loose, the toner charge rises worse, causing toner scattering and fogging.
[0062]
Carrier particles of 62 μm or more are closely correlated with the sharpness of the image, and the content of the coarse powder is preferably 2 to 20% by weight. When the content of the coarse powder exceeds 20% by weight, the toner carrying ability of the carrier is lowered, the scattering of the toner to the non-image portion is increased, the resolution of the image is lowered, and the highlight reproducibility is lowered. If it is less than% by weight, the fluidity of the two-component developer is lowered, the developer is displaced in the developing device, and a stable image is hardly obtained.
[0063]
Furthermore, in the carrier used in the present invention, the specific surface area S calculated by the air permeation method.₁And the following formula (II)
[0064]
[Expression 1]

Specific surface area S calculated from₂Ratio to (S₁/ S₂) Is preferably 1.2 to 2.0, more preferably 1.3 to 1.8, and still more preferably 1.4 to 1.7.
[0065]
S₁/ S₂Is less than 1.2, the surface of the carrier becomes smooth, and the adhesion of the resin to the carrier core material decreases, resulting in toner scattering, fogging, and image unevenness. S₁/ S₂Is larger than 2.0, the unevenness on the surface of the carrier becomes too large, and the resin coating layer on the surface of the magnetic carrier core material particles tends to be non-uniform. As a result, the uniformity of charging cannot be obtained, and fog, toner scattering Is likely to occur, and carrier adhesion is also likely to occur.
[0066]
Furthermore, in order to make the effect of the present invention more effective, the apparent density of the carrier is preferably 1.2 to 3.2 g / cm.², More preferably 1.5 to 2.8 g / cm²It is good to do. When the apparent density is smaller than the lower limit of the above range, carrier adhesion is likely to occur. When the apparent density is larger than the upper limit of the above range, circulation of the two-component developer is deteriorated and toner scattering is likely to occur. , Image quality deterioration will also be accelerated.
[0067]
In order to make the present invention more effective, the carrier current value is preferably 20 to 300 μA, more preferably 30 to 250 μA, and still more preferably 40 to 200 μA.
[0068]
If the current value is less than 20 μA, the charge transfer on the carrier surface is not sufficiently performed, and the ability to impart charge to the toner is reduced, fogging and toner scattering are likely to occur. Carrier adhesion to the drum and bias leakage are likely to occur, and image defects are likely to occur.
[0069]
The magnetic characteristics of the carrier are influenced by a magnet roller built in the developing sleeve, and greatly affect the developing characteristics and transportability of the two-component developer.
[0070]
In the present invention, a two-component developer having a carrier made of magnetic particles and an insulating color toner is developed on a developing sleeve having a built-in magnet roller, the developing roller is fixed and the developing sleeve is rotated alone. When developing the electrostatic latent image held on the surface of the electrostatic latent image holding member with the two-component developer, the magnetic roller has a repulsive pole. (2) The magnetic flux density in the development region is 500 to 1200 gauss, and (3) the saturation magnetization of the carrier is 20 to 70 Am.²/ Kg is excellent in image uniformity and gradation reproducibility in color copying.
[0071]
Carrier saturation magnetization is 70 Am²/ Kg (with respect to an applied magnetic field of 3000 oersteds), the brush-like ears composed of the carrier and the toner on the developing sleeve facing the electrostatic latent image on the photoconductor are firmly tightened during development. And the gradation and halftone reproduction are reduced.²If it is less than / kg, it becomes difficult to satisfactorily hold the toner and carrier on the developing sleeve, and carrier adhesion and toner scattering tend to occur.
[0072]
Examples of ferrite carriers containing MgO are described in, for example, JP-A-59-1159, JP-A-58-123551, and JP-A-55-65406, but these have a controlled particle size distribution. However, simply combining with toner of 1 to 9 μm does not satisfy the charging stability and durability, and is different from the present invention.
[0073]
Furthermore, although JP-A-2-33159 discloses that MgO may be contained, MgO is positively employed, its surface activity is utilized, particle size distribution control and durability of the resin-coated carrier. There is no suggestion of improvement, which is different from the present invention.
[0074]
As the curing agent used in the present invention, the following general formula (III)
[0075]
[Chemical Formula 3]

An oxime type curing agent represented by That is, the oxime type silane coupling agent is very excellent in terms of appropriate control of residual reactive groups in the silicone resin, storage stability, and cost.
[0076]
Acetic acid type (acetoxy silane) and acetone type (propenoxy silane) are known as highly reactive coupling agents, but they have achieved a stable reaction between the carrier core particles described above and a silicone resin. Since it is very difficult to set the conditions for adequately remaining the product, it is known that the production stability is inferior, which is not preferable for the present invention.
[0077]
As for the hardening | curing agent in this invention, what is shown by following (1)-(4) is mentioned, for example.
[0078]
[Formula 4]

[0079]
The addition amount of the curing agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the siloxane solid. If the amount is less than 0.1 part by weight, a sufficient crosslinking effect cannot be obtained. If the amount exceeds 10 parts by weight, the residue cannot be removed sufficiently or an insufficiently reacted compound remains, and the charging characteristics and strength are low. It will decline. In the present invention, the siloxane solid component indicates a non-volatile component at 120 ° C.
[0080]
In this invention, as an aminosilane coupling agent which can be contained in the reactive silicone resin used for a resin coating layer, what is shown to following (5)-(13) is mentioned, for example.
[0081]
[Chemical formula 5]

[0082]
These can be used alone or in combination of two or more. Among them, the following coupling agents having at least one nitrogen atom having one hydrogen atom are preferred for use in the present invention in view of compatibility, reactivity and stability.
[0083]
[Chemical 6]

[0084]
The amount of the coupling agent added is preferably 0.1 to 8 parts by weight, more preferably 0.3 to 5 parts by weight with respect to 100 parts by weight of the siloxane solid. If the amount is less than 0.1 parts by weight, a sufficient addition effect cannot be obtained, and the chargeability is likely to deteriorate and the coating strength decreases. If the amount exceeds 8 parts by weight, a sufficient reaction is not performed, and conversely the coating strength decreases. End up.
[0085]
In the present invention, the coupling agent is further represented by the following general formula (IV):
R_4-a-Si-Xa Formula (IV)
(Wherein R_4-aRepresents a substituent selected from the group consisting of a vinyl group, a methacryl group, an epoxy group, an amino group, a mercapto group and derivatives thereof, and X represents a halogen or an alkoxy group. ) May be used in combination.
[0086]
Examples of such a coupling agent include those shown in the following (14) to (16).
(14) CH_Three= CH-Si- (OCH_Three)_Three
(15) CH_Three-Si- (OCH_Three)_Three
(16) CH_Three-Si- (OC₂H_Five)_Three
[0087]
As a method of forming the resin coating layer on the surface of the magnetic carrier core particles, the resin composition is dissolved in an appropriate solvent, the magnetic carrier core particles are immersed in the resulting solution, and then the solvent is removed, dried, A method of baking at high temperature, or a method of floating magnetic carrier core particles in a fluidized system, spraying and applying a solution in which the resin composition is dissolved, drying and baking at high temperature, simply magnetic carrier core particles and resin Any method of mixing a powder of the composition or an aqueous emulsion can be used.
[0088]
The method preferably used in the present invention is 0.1 to 5 parts by weight of water, preferably 0 in 100 parts by weight of a solvent containing 5% by weight or more, preferably 20% by weight or more of a polar solvent such as ketones or alcohols. A method of using a mixed solvent containing 3 to 3 parts by weight is preferable for firmly attaching the reactive silicone resin to the magnetic carrier core particles. If the water content is less than 0.1 parts by weight, the reactive silicone resin will not be sufficiently hydrolyzed, and it will be difficult to coat the surface of the magnetic carrier core particles with a thin layer. Control becomes difficult and conversely the coating strength is reduced.
[0089]
In the present invention, a carrier and a toner are mixed to prepare a two-component developer, and the mixing ratio is 1 to 12 parts by weight, preferably 2 to 9% by weight, as the toner concentration in the two-component developer. In general, good results are obtained. When the toner concentration is less than 1% by weight, the image density becomes low. When the toner concentration exceeds 12% by weight, fogging and in-machine scattering increase, and the useful life of the two-component developer is shortened.
[0090]
The two-component developer of the present invention is composed of the above carrier and toner, and a preferred configuration of the toner constituting the two-component developer in combination with the carrier will be described.
[0091]
The toner used in the present invention has toner particles and surface-treated inorganic fine particles having a weight average particle diameter of 0.001 to 0.2 μm as external additives, and has the toner particles and the external additives. A toner having a weight average particle diameter of 1 to 9 μm is a preferable first form of the toner.
[0092]
Examples of the inorganic fine powder used as an external additive for the toner include alumina, titanium oxide and silica. Among these, alumina or titanium oxide fine particles are particularly preferable because they further stabilize the charging of the toner.
[0093]
Further, the inorganic fine powder is preferably hydrophobized in order to reduce the dependency of the toner charge amount on the environment such as temperature and humidity and to prevent the toner from being separated from the toner surface. Examples of the hydrophobizing agent include coupling agents such as silane coupling agents, titanium coupling agents, and aluminum coupling agents, and oils such as silicone oil, fluorine-based oil, and various modified oils.
[0094]
Among the above hydrophobizing agents, a coupling agent is particularly preferable from the viewpoint of stabilizing charging of the toner and imparting fluidity.
[0095]
Therefore, as the external additive used in the present invention, particularly preferably, alumina or titanium oxide fine particles subjected to surface treatment while hydrolyzing the coupling agent are extremely effective in terms of stabilizing the charge and imparting fluidity. It is.
[0096]
The inorganic fine powder subjected to the hydrophobic treatment preferably has a degree of hydrophobicity of preferably 20 to 80%, more preferably 40 to 80%.
[0097]
If the degree of hydrophobicity of the inorganic fine powder is less than 20%, the amount of charge will decrease significantly due to long-term standing under high humidity, and a mechanism for promoting charging on the hardware side will be required, which will complicate the device and increase the degree of hydrophobicity. If it exceeds 80%, it becomes difficult to control the charge of the inorganic fine powder itself, and as a result, the toner is likely to be charged up under low humidity.
[0098]
The inorganic fine powder subjected to the hydrophobization treatment has a weight average particle diameter of 0.001 μm to 0.2 μm, preferably 0.005 μm to 0.15 μm. Good in terms of preventing release from
[0099]
When the weight average particle size is less than 0.001 μm, the toner particles are easily embedded in the surface of the toner particles, and the toner is deteriorated, so that the durability is easily lowered.
[0100]
When it exceeds 0.2 μm, it is difficult to sufficiently obtain the fluidity of the toner, and the toner is likely to be non-uniformly charged. As a result, toner scattering and fogging are likely to occur.
[0101]
The inorganic fine powder subjected to the hydrophobization treatment preferably has a light transmittance of 40% or more at a light length of 400 nm.
[0102]
That is, the inorganic fine powder used in the present invention is not necessarily dispersed in the form of primary particles when actually contained in the toner, even if the primary particle size is small. It may be present in Therefore, no matter how small the primary particle size is, the effect of the present invention will be reduced if the effective diameter of the secondary particles is large. However, the higher the light transmittance at 400 nm which is the lower limit wavelength in the visible region, the smaller the secondary particle diameter, the better the fluidity imparting ability, and the clearness of the projected image of OHP in the case of color toner. I can expect. The reason why 400 nm is selected is the boundary region between ultraviolet and visible, and since it is said that a particle having a particle diameter of 1/2 or less of the light wavelength is transmitted, the transmittance of wavelengths longer than that naturally becomes large, so It is meaningless.
[0103]
In the present invention, the toner having toner particles and an external additive may have a weight average particle diameter of 1 to 9 μm, preferably 2 to 8 μm, from the viewpoint of achieving both high image quality and high durability.
[0104]
When the weight average particle diameter of the toner is less than 1 μm, the mixing property with the carrier is lowered, causing defects such as toner scattering and fogging, and when exceeding 9 μm, the reproducibility of the minute dot latent image is deteriorated. Alternatively, scattering at the time of transfer occurs, which hinders high image quality.
[0105]
Examples of the colorant contained in the toner used in the present invention include known dyes and pigments such as phthalocyanine blue, indanthrene blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, and benzidine yellow. Can be used. The content is preferably 12 parts by weight or less, more preferably 0.5 to 9 parts by weight with respect to 100 parts by weight of the binder resin so as to reflect sensitively the permeability of the OHP film.
[0106]
The toner used in the present invention may be mixed with an additive as long as it does not impair the properties of the toner. Examples of such an additive include lubricants such as Teflon, zinc stearate, and polyvinylidene fluoride. Or fixing aids (for example, low molecular weight polyethylene, low molecular weight polypropylene, etc.), organic resin particles, and the like.
[0107]
In the production of the toner used in the present invention, the constituent materials are well kneaded by a heat kneader such as a heat roll, kneader, extruder, etc., and then obtained by mechanical pulverization and classification. A method in which the toner raw material is dispersed and then spray-dried, or a predetermined material is mixed with a polymerizable monomer that can constitute a binder resin, and then the emulsion suspension is polymerized to obtain a toner. The obtained polymerized toner manufacturing method can be applied.
[0108]
Various resins are used as the binder resin used in the toner of the present invention.
[0109]
For example, polystyrene, styrene-butadiene copolymer, styrene copolymer such as styrene-acrylic copolymer, ethylene copolymer such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer. Phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, and maleic acid resin. Any resin is not particularly limited in its production method.
[0110]
Among these resins, the effect of the present invention is particularly great when a polyester resin having a high negative chargeability is used. That is, the polyester resin is excellent in fixability and suitable for color toners, but has a strong negative chargeability and is likely to be overcharged. However, the polyester resin is used as a binder resin for the toner combined with the carrier of the present invention. When the toner is used, the adverse effects are improved and an excellent toner can be obtained.
[0111]
In particular, the following formula (V)
[0112]
[Chemical 7]

(In the formula, R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)
And a carboxylic acid component (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid). A polyester resin obtained by co-condensation polymerization of the diol component and the carboxylic acid component is more preferable because it has sharp melting characteristics.
[0113]
The toner used in the present invention has a weight average particle diameter of 1 to 9 μm, includes a binder resin having a polyester resin, and has an acid value of 1 to 20 KOH mg / g.
[0114]
That is, by using the toner having an acid value of 1 to 20 KOHmg / g, charging stability with a carrier in which magnetic carrier core particles formed of the specific magnetic ferrite component are coated with a resin coating layer is used. Even if an original having a high image ratio is used, a two-component developer free from fogging and toner scattering can be achieved over a long period of time.
[0115]
Here, when the acid value is smaller than 1 KOHmg / g, the rising of the charge is lowered, and as a result, the fog tends to deteriorate. When the acid value is larger than 20 KOHmg / g, the chargeability under high humidity is lowered. As a result, fog and toner scattering occur.
[0116]
In the toner used in the present invention, in order to control the acid value of the toner to 1 to 20 KOHmg / g and improve the low-temperature fixability and durability of the toner, a trivalent or higher polyvalent acid is used as the acid component of the binder resin. It is good to contain carboxylic acid 0.1-20 mol%, More preferably, 0.1-10 mol%. More preferably, the toner containing the binder resin having the polyester resin has a glass transition temperature (Tg) in the range of 45 to 70 ° C.^FiveThe temperature (Tm) showing the apparent viscosity of the poise is preferably in the range of 8 to 120 ° C.
[0117]
Particularly preferably, the bisphenol derivative represented by the formula (V) described above in the first preferred embodiment of the toner or a substituted product thereof is used as a diol component, and a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof. Is a carboxylic acid component (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid), and a polyester resin obtained by co-condensation polymerization of the diol component and the carboxylic acid component is sharp. It is more preferable because it has excellent melting characteristics.
[0118]
That is, the polyester-based resin is excellent in fixability and suitable for color toners, but has a strong negative chargeability and tends to be excessively charged. However, the acid value is 1 to 20 KOHmg / g, preferably 2 to 18 KOHmg / g. g, more preferably a toner having an acid value of 3 to 15 KOHmg / g and a carrier obtained by coating the surface of magnetic carrier core particles formed of the magnetic ferrite component with a resin coating layer, An improved two-component developer can be obtained.
[0119]
As the binder resin used in the toner of the present invention, various material resins may be used in combination with the aforementioned polyester resin.
[0120]
For example, styrene copolymers such as polystyrene, styrene-butadiene copolymer, styrene-acrylic copolymer, ethylene copolymers such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer Phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, and maleic acid resin. Any resin is not particularly limited in its production method.
[0121]
Further, the toner is preferably used by adding an external additive to the toner particles, and as the external additive, the toner described in the first preferred embodiment of the toner is preferably used.
[0122]
Next, the image forming method of the present invention using the above two-component developer will be described.
[0123]
In the image forming method of the present invention, a two-component developer having a toner and a carrier is circulated and conveyed on a developer carrier, and the latent image carrier and a developer carrier opposite to the latent image carrier are formed on the latent image carrier. The held latent image is developed with toner of a two-component developer on the developer carrying member.
[0124]
The magnetic characteristics of the carrier are influenced by a magnet roller built in the developing sleeve, and greatly affect the developing characteristics and transportability of the developer.
[0125]
In the image forming method of the present invention, among the developing sleeve (developer carrier) and the magnet roller incorporated therein, for example, the magnet roller is fixed and the developing sleeve is rotated alone to insulate the carrier made of magnetic particles. A two-component developer made of a color toner is circulated and conveyed on the developing sleeve, and the electrostatic latent image held on the surface of the electrostatic latent image holding member is developed with the two-component developer.
[0126]
In the image forming method of the present invention, as described above, (1) the magnet roller has a five-pole configuration having a repulsive pole, (2) the magnetic flux density in the developing region is 500 to 1200 gauss, and (3) carrier saturation. Magnetization is 20 to 70 Am²/ Kg is excellent in image uniformity and gradation reproducibility in color copying.
[0127]
In the image forming method of the present invention, it is preferable to develop the electrostatic latent image with a toner of a two-component developer by applying a development bias in the development region.
[0128]
A particularly preferable developing bias will be described in detail below.
[0129]
In the image forming method of the present invention, a first voltage for directing the toner from the latent image holding member to the developer carrying member in the development region, a second voltage for directing the toner from the developer carrying member to the latent image holding member, A third voltage between the first voltage and the second voltage is applied to the developer carrying member to form a developing electric field between the latent image holding member and the developer carrying member. It is preferable to develop the held latent image with a toner of a two-component developer on the developer carrying member.
[0130]
Further, the total time for applying to the developer carrier the first voltage for directing the toner from the latent image carrier to the developer carrier and the second voltage for directing the toner from the developer carrier to the latent image carrier. (T₁), The time (T) during which the third voltage between the first voltage and the second voltage is applied to the developer carrier.₂) Is particularly preferable for the purpose of rearranging the toner on the latent image holding member and faithfully reproducing the latent image.
[0131]
Specifically, in the development area, between the latent image holding member and the developer carrying member, the toner flows from the latent image holding member to the developer carrying member and from the developer carrying member to the latent image holding member. After forming the electric field at least once, in the image portion of the latent image holding member, the toner moves from the developer carrying member to the latent image holding member, and in the non-image portion of the latent image holding member, the toner is transferred from the latent image holding member to the developer. The latent image held on the latent image carrier is developed with toner of a two-component developer carried on the developer carrier by forming an electric field directed to the carrier for a predetermined time. Total time (T) for forming an electric field from the carrier to the developer carrier and an electric field from the developer to the latent image carrier₁) In the image portion of the latent image carrier, the toner forms an electric field from the developer carrier to the latent image carrier, and in the non-image portion of the latent image carrier, the toner forms an electric field from the latent image carrier to the developer carrier. Time (T₂) Is preferably longer.
[0132]
In the developing method in which development is performed by forming the above-described specific developing electric field, that is, an alternating electric field, carrier development is less likely to occur when the developing electric field is periodically turned off. The reason for this is not clear yet, but can be considered as follows.
[0133]
In other words, in the conventional continuous sine wave or rectangular wave, when the electric field strength is increased in order to achieve high image quality density, the toner and the carrier are integrated to reciprocate between the latent image carrier and the developer carrier. As a result, the carrier strongly rubs against the latent image holding member, and carrier adhesion occurs. This tendency becomes more conspicuous as there are more fine powder carriers.
[0134]
However, when a specific alternating electric field as in the present invention is applied, the toner or carrier reciprocates between the developer carrying member and the latent image holding member in one pulse, and therefore the surface of the subsequent latent image holding member. Potential difference between DC component of potential and development bias V_contIs V_contIf <0, V_contWorks to fly the carrier from the developer carrier, but by controlling the magnetic properties of the carrier and the magnetic flux density in the developing region of the magnet roller, carrier adhesion can be prevented, and V_contIf> 0, the magnetic field force and V_contWorks to attract the carrier to the developer carrying member, and carrier adhesion does not occur.
[0135]
A preferred embodiment of the electrostatic latent image carrier that can be used in the image forming method of the present invention will be described with reference to FIG.
[0136]
The electrostatic latent image holding body 1 is provided with a photosensitive layer 43 and a protective layer 44 on a conductive support 41, so that at least the protective layer 44 reduces the frictional resistance of the surface of the electrostatic latent image holding body 1. The protective layer 44 is mechanically polished, and the average surface roughness of the protective layer 44 is preferably a 10-point average surface roughness R defined by JIS standard B061._z(Hereinafter, simply referred to as average surface roughness) is preferably 0.01 to 1.5 μm.
[0137]
If the average surface roughness is within the above range, the friction between the cleaning blade 50 and the surface of the electrostatic latent image holding member 1 is sufficiently small, and image defects do not appear even after repeated use. Light reproduction is also very good.
[0138]
The content of the fluorine atom-containing resin fine particles capable of effectively reducing the friction coefficient on the surface of the electrostatic latent image holding member 1 is 5 to 40% by weight, preferably 10%, based on the total weight of the protective layer 44 in the protective layer 44. ~ 40 wt% is good. The film thickness of the protective layer 44 is preferably in the range of 0.05 μm to 8.0 μm, more preferably in the range of 0.1 μm to 6.0 μm.
[0139]
In the present invention, when the photosensitive layer 43 part also contains fluorine atom-containing resin fine particles, the photosensitive layer 43 is thicker than the thin protective layer 44, so the content of the fine particles is limited. Specifically, the content in the photosensitive layer 43 is preferably 10% by weight or less, more preferably 7% by weight or less, based on the total weight of the photosensitive layer 43.
[0140]
Even when the amount of fluorine atom-containing resin fine particles in the photosensitive layer 43 is limited, when the total thickness of the photosensitive layer 43 is large, particularly when photocarriers are generated mainly on the support side of the photosensitive layer 43, light scattering causes Sensitivity degradation and image uniformity are significantly reduced. Even if the photosensitive layer 43 is too thin, it may cause a decrease in sensitivity and a decrease in charging ability due to an increase in the capacitance of the photosensitive layer 43. Further, even when the photosensitive layer 43 does not contain the fine particles, it is not preferable to make the photosensitive layer 43 extremely thick. The reason is that the protective layer 44 containing the fine particles is laminated on the photosensitive layer 43, so that the protective layer 44 becomes a light scattering layer, and particularly when photocarriers are generated mainly on the support side of the photosensitive layer, This is because the farther the carrier generation portion is from the light scattering layer, that is, the thicker the photosensitive layer 43, the longer the optical path length of the scattered light, and the greater the influence of light scattering.
[0141]
Therefore, the total thickness of the photosensitive layer 43 is preferably 10 to 35 μm, more preferably 15 to 30 μm in total with the protective layer 44. The amount of the fine particles contained in the photosensitive layer 43 is preferably as small as possible, so that the average content of the fine particles in the total film thickness of the photosensitive layer 43 and the protective layer 44 is as follows. It is preferable that it is 17.5% by weight or less based on the total weight.
[0142]
In the present invention, the fluorine atom-containing resin fine particles used in the electrostatic latent image carrier are polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. , A tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-ethylene copolymer, and a tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer. It is what. Commercially available fluorine atom-containing resin fine particles can be used as they are. Those having a molecular weight of 30,000 to 5,000,000 can be used, and those having a particle diameter of 0.01 to 10 μm, preferably 0.05 to 2.0 μm can be used.
[0143]
In the present invention, the photosensitive layer 43 of the electrostatic latent image holding member contains at least a charge generation material and a charge transport material as an organic photoconductive substance.
[0144]
Examples of charge generation materials include phthalocyanine pigments, polycyclic quinone pigments, trisazo pigments, disazo pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium salt dyes, squalium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, Xanthene dyes, quinoneimine dyes, triphenylmethane dyes, styryl dyes, selenium, selenium-tellurium alloys, amorphous silicon, and cadmium sulfide.
[0145]
Examples of charge transport materials include pyrene compounds, N-alkylcarbazole compounds, hydrazone compounds, N, N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, styryl compounds, stilbene compounds, Examples thereof include polynitro compounds, polycyano compounds, and pendant polymers in which these compounds are fixed on the polymer.
[0146]
In many cases, the protective layer and the photosensitive layer are formed by dispersing and containing the fluorine atom-containing resin fine particles, the charge generation material, and the charge transport material in a binder resin having film forming properties. Such binder resins include polyester, polyurethane, polyacrylate, polyethylene, polystyrene, polycarbonate, polyamide, polypropylene, polyimide, phenol resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, polyamide. -Imido, nylon, polysulfone, polyallyl ether, polyacetal, butyral resin are mentioned.
[0147]
Next, the layer structure of the electrostatic latent image holding member will be described. The conductive support 41 is made of a metal or alloy such as iron, copper, gold, silver, aluminum, zinc, titanium, lead, nickel, tin, antimony, or indium, or an oxide, carbon, or conductive polymer of the metal. Is possible. The shape includes a drum shape such as a cylindrical shape and a cylindrical shape, and a belt shape and a sheet shape. The conductive material may be molded as it is, used as a paint, deposited, or processed by etching or plasma treatment. In the case of paint, paper and plastic are used as a support as well as the above metals and alloys.
[0148]
The photosensitive layer 43 in the electrostatic latent image holding member 1 may have a single layer structure or a stacked structure. In the case of a laminated structure, it is composed of at least a charge generation layer 43a and a charge transport layer 43b. In the case where the charge generation layer 43a is provided on the conductive support 41 side and the case where the charge transport layer 43b is provided. Charging polarity and toner polarity used are different. The film thickness of the charge generation layer 43a is preferably 0.001 to 6 μm, more preferably 0.01 to 2 μm. The content of the charge generation material contained in the charge generation layer 43a is preferably 10 to 100% by weight, more preferably 50 to 100% by weight, based on the total weight of the charge generation layer. The thickness of the charge transport layer is obtained by subtracting the thickness of the charge generation layer 43a from the thickness of the photosensitive layer 43. The content of the charge transport material contained in the charge transport layer 43b is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the charge generation layer.
[0149]
An undercoat layer 42 may be provided between the conductive support 41 and the photosensitive layer 43. The undercoat layer 42 functions as charge injection control or an adhesive layer at the interface. The undercoat layer 42 is mainly made of a binder resin, but may contain the metal or alloy, or an oxide, salt, or surfactant thereof. As the binder resin for forming the undercoat layer 42, those mentioned as the binder resin for the photosensitive layer 43 can be used, and the thickness of the undercoat layer is preferably 0.05 to 7 μm, more preferably 0.00. 1 to 2 μm.
[0150]
As described above, the protective layer is preferably provided on the photosensitive layer and is composed of resin fine particles containing at least a high concentration of fluorine atoms and a binder resin.
[0151]
A vapor deposition or coating method is used as a method of manufacturing the electrostatic latent image holding member. The coating method can form films having various compositions in a wide range from a thin film to a thick film. Specifically, the coating is performed using a coating method such as a bar coater, knife coater, dip coating, spray coating, beam coating, electrostatic coating, roll coater, attritor or powder coating.
[0152]
The paint used for applying the protective layer is obtained by dispersing the fluorine atom-containing resin fine particles in a binder resin and a solvent. As a dispersion method, a method such as a ball mill, an ultrasonic wave, a Peyton shaker, a red devil, or a sand mill is used. A similar dispersion method can also be used when the conductive fine powder, pigment, or charge generation material is a pigment.
[0153]
An image forming apparatus capable of carrying out the image forming method of the present invention will be described with reference to FIG.
[0154]
In FIG. 1, the image forming apparatus has a photosensitive drum 1 as an electrostatic latent image holding member. In the developing device 4, the inside of the developing container 16 is separated by a partition 17 into a developing chamber (first chamber) R.₁And stirring chamber (second chamber) R₂And stirring chamber R₂The toner storage chamber R is spaced above the partition wall 17._ThreeIs formed. Development chamber R₁And stirring chamber R₂A developer 19 is accommodated in the toner storage chamber R._ThreeA supply toner (non-magnetic toner) 18 is accommodated in the interior. The toner storage chamber R_ThreeIs provided with a replenishing port 20, and an amount of replenishing toner 18 corresponding to the toner consumed through the replenishing port 20 is added to the stirring chamber R.₂Dropped into the inside.
[0155]
Development chamber R₁A conveying screw 13 is provided inside, and the developing chamber R is driven by the rotation of the conveying screw 13.₁The developer 19 is conveyed toward the longitudinal direction of the developing sleeve 11. Similarly, storage room R₂A conveying screw 14 is provided inside, and the rotation of the conveying screw 14 causes the stirring chamber R to be fed from the replenishing port 20.₂The toner dropped in is conveyed along the longitudinal direction of the developing sleeve 11.
[0156]
The developer 19 is a two-component developer having a nonmagnetic toner and a magnetic carrier.
[0157]
An opening is provided in a portion of the developing container 16 adjacent to the photosensitive drum 1, and the developing sleeve 11 protrudes from the opening, and a gap is provided between the developing sleeve 11 and the photosensitive drum 1. A bias applying means 30 for applying a bias is disposed on the developing sleeve 11 formed of a nonmagnetic material.
[0158]
As described above, the magnet roller as the magnetic field generating means fixed in the developing sleeve 11, that is, the magnet 12, is provided with the developing magnetic pole S.₂And magnetic pole N located downstream thereof₂And a magnetic pole N for transporting the developer 19_Three, S₁, N₁And have. The magnet 12 is a developing magnetic pole S.₂Is disposed in the developing sleeve 11 so as to face the photosensitive drum 1. Development magnetic pole S₂Forms a magnetic field in the vicinity of the developing portion between the developing sleeve 11 and the photosensitive drum 1, and a magnetic brush is formed by the magnetic field.
[0159]
The regulating blade 15 that is disposed above the developing sleeve 11 and regulates the layer thickness of the developer 19 on the developing sleeve 11 includes an end of the nonmagnetic blade 15 made of a nonmagnetic material such as aluminum or SUS316, and the developing sleeve. The distance from the eleventh surface is 300 to 1000 μm, preferably 400 to 900 μm. If this distance is smaller than 300 μm, the magnetic carrier is clogged in the meantime, and the developer layer is likely to be uneven, and the developer necessary for good development cannot be applied, and development with low unevenness in density is difficult. There is a problem that only images can be obtained. In order to prevent non-uniform application (so-called blade clogging) due to unnecessary particles mixed in the developer, 400 μm or more is preferable. If it is larger than 1000 μm, the amount of developer applied on the developing sleeve 11 increases, and the predetermined developer layer thickness cannot be regulated, and the magnetic carrier particles adhere to the photosensitive drum 1 and the developer is not circulated. There is a problem that development regulation by the magnetic blade 15 is weakened and toner tribo is insufficient and fogging easily occurs.
[0160]
The angle θ1 is −5 ° to 35 °, preferably 0 ° to 25 °. When θ1 <−5 °, the developer thin layer formed by the magnetic force acting on the developer, the reflection force, the cohesive force, etc. is sparse and uneven, and when θ> 35 °, the nonmagnetic blade The developer application amount increases and it is difficult to obtain a predetermined developer amount.
[0161]
Even when the sleeve 11 is rotationally driven in the direction of the arrow, the movement of the magnetic carrier particle layer becomes slower as it moves away from the sleeve surface due to the balance between the restraining force based on the magnetic force and gravity and the conveying force in the moving direction of the sleeve 11. . Of course, some fall under the influence of gravity.
[0162]
Therefore, magnetic pole N₁And N₂As the magnetic carrier particle layer is closer to the sleeve, the magnetic pole N₁The moving layer is formed by conveying in the direction. Due to the movement of the magnetic carrier particles, the developer is transported to the developing area as the developing sleeve 11 rotates and is used for development. Reference numeral 21 denotes an upstream toner scattering suppression unit, and reference numeral 22 denotes a downstream toner scattering suppression unit. The upstream toner scattering suppression unit 21 and the downstream toner scattering suppression unit 22 suppress the occurrence of toner scattering.
[0163]
Another example of an image forming apparatus that can carry out the image forming method of the present invention will be described with reference to FIG.
[0164]
The developing device shown in FIG. 7 has a nonmagnetic developing sleeve (developer carrying member) as a developer carrying member in the developing chamber 145 of the developing container 102 facing the electrostatic latent image holding member 101 rotated in the direction of arrow a. Body) 121, and a magnetic roller 122 as a magnetic field generating means is left stationary in the developing sleeve 121. The magnetic (magnet) roller 122 is moved in the order of the rotation of the arrow b in the order of the arrow b.₁, N₁, S₂, N₂, N_ThreeIs magnetized.
[0165]
In the developing chamber 145, a two-component developer 141 in which the toner 140 and the magnetic carrier 143 are mixed is accommodated.
[0166]
When the developer 141 is sent into the stirring chamber 142 of the developing container 102 through one opening (not shown) of the partition wall 148 at the upper end opening at one end of the developing chamber 145, the developer 141 is supplied from the toner chamber 147 into the stirring chamber 142. The toner 140 is replenished and conveyed to the other end of the agitating chamber 142 while being mixed by the first developer agitating / conveying means 150 in the agitating chamber 142. The developer 141 conveyed to the other end of the agitating chamber 142 is returned to the developing chamber 145 through the other opening (not shown) of the partition wall 148, where the developer 141 and the second developer agitating / conveying means 151 in the developing chamber 145 are connected. Then, the developer is supplied to the developing sleeve 121 while being agitated and conveyed by a third developer agitating / conveying means that conveys the developer in the upper part in the developing chamber 145 in the direction opposite to the conveying direction by the conveying means 151.
[0167]
The developer 141 supplied to the developing sleeve 121 is magnetically constrained by the magnetic force of the magnet roller 122, and is carried on the developing sleeve 121, and a developer regulating member provided on a substantially top portion of the developing sleeve 121. While being formed in a thin layer of the developer 141 on the developing sleeve 121 due to the restriction by the blade 123, the developing sleeve 121 is conveyed to the developing unit 110 facing the electrostatic latent image holding member 101 as the developing sleeve 121 rotates in the arrow b direction. The electrostatic latent image on the electrostatic latent image holding member 101 is then developed. The remaining two-component developer 141 that has not been consumed for development is collected in the developing container 102 by the rotation of the developing sleeve 121. Reference numeral 103 denotes an upstream toner scattering suppression unit, and reference numeral 104 denotes a downstream toner scattering suppression unit. The upstream toner scattering suppression unit 103 and the downstream toner scattering suppression unit 104 suppress the occurrence of toner scattering.
[0168]
N of the same polarity in the developer container 102₂, N_ThreeThe remaining two-component developer 141 that remains undeveloped magnetically on the developing sleeve 121 is peeled off by a repulsive magnetic field between them. Above magnetic pole N₂In order to prevent toner scattering when the two-component developer 141 rises along the lines of magnetic force, an elastic seal member 131 is placed at one end of the developer container 102 in contact with the developer 141. Fixed and installed.
[0169]
Furthermore, as a result of intensive studies on the image density, highlight reproducibility, and fine line reproducibility of the color image forming method, the present inventors have formed a specific development electric field described above with toner having a specific particle size distribution described below. It has been found that when used in an image forming method using the developing method, high image quality excellent in high image density, highlight reproduction, and fine line reproduction can be achieved.
[0170]
That is, the toner used in the present invention contains at least toner particles and an external additive, the toner has a weight average particle diameter of 3 to 7 μm, and the toner has a particle diameter of 5.04 μm or less. 10 to 70% by weight of toner having a particle size of 4 μm or less, more than 2% by volume, 2 to 20% by volume of toner having a particle size of 8 μm or more, and a particle size of 10.08 μm or more A toner containing 0 to 6% by volume of toner is preferable.
[0171]
The toner having the above-described particle size distribution can faithfully reproduce the latent image formed on the photoconductor, and is excellent in reproducibility of minute dot latent images such as halftone dots and digital images. An image having excellent gradation and resolution of the light portion is provided. Furthermore, even when copying or printing is continued, high image quality can be maintained, and even in the case of high density images, it is possible to perform good development with less toner consumption than conventional non-magnetic toners. This also has an advantage in reducing the size of the copying machine or printer main body.
[0172]
However, even if the toner has excellent latent image reproducibility, the conventional continuous sine wave or rectangular wave has a sufficient electric field strength for a latent image with a low development contrast such as a highlight latent image. Therefore, in the continuous pulse, the ratio that the toner does not reach the latent image holding member increases. That is, under the bias under the above conditions, the toner vibrates so as not to reach the latent image holding member from the developer carrying member.
[0173]
However, according to the present invention, since a specific development electric field as described later is formed in the development area, a good highlight image without roughness can be obtained. That is, in one pulse, it is the same that the toner vibrates so that it does not reciprocate between the developer carrier and the electrostatic latent image carrier, but thereafter the surface potential of the electrostatic latent image carrier and the DC of the development bias Component potential difference V_contIs V_contWhen <0, the direct current component works to attract the toner to the developer carrier, and the toner is biased toward the developer carrier, and vice versa._contWhen> 0, the direct current component acts to attract the toner to the electrostatic latent image holding body according to the latent image potential, and an amount of toner corresponding to the latent image potential is biased toward the electrostatic latent image holding body. Further, when developing under such conditions, the toner that reaches the latent image holding member repeats vibrations there and concentrates on the latent image portion. For this reason, the dot shape is made uniform, and a good image without unevenness can be obtained.
[0174]
From the above, when a latent image is visualized with a developing bias under the above conditions, no dot is lost even in the case of a highlight latent image. Further, by repeating the vibration on the latent image holding member, the toner concentrates on the latent image portion, and each dot is faithfully reproduced. In the two-component developer, there is no unevenness due to the contact state of the magnetic brush. A uniform halftone image can be output.
[0175]
Below, the measuring method in this invention is described.
[0176]
(1) Measurement of carrier magnetic properties
As the apparatus, a BHU-60 type magnetization measuring apparatus (manufactured by Riken Measurement) is used. About 1.0 g of the measurement sample is weighed and packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm, and set in the above-mentioned apparatus. In the measurement, an applied magnetic field is gradually applied and changed to a maximum of 3,000 Oersted. Next, the applied magnetic field is decreased, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, saturation magnetization, residual magnetization, and coercive force are obtained.
[0177]
(2) Measurement of carrier particle size distribution
The apparatus used was an SRA type of a Microtrac particle size analyzer (Nikkiso Co., Ltd.) and was set at a range of 0.7 to 125 μm, and a 50% particle size was calculated from the volume standard.
[0178]
(3) Measurement of carrier current value
(1) Weigh 800 g of the carrier and expose it to the environment for 15 minutes or more. (Indoor temperature 22-25 ° C, humidity 50-54%)
{Circle around (2)} A device is provided in which a counter roller is provided at a distance of 1 mm, facing a conductive sleeve having a built-in magnet roller and provided with a spike control blade.
(3) The carrier is magnetically attracted between the sleeve and the counter electrode.
(4) Rotate the magnet roller in the sleeve to bring the carrier raised on the counter electrode into contact, load a DC voltage of 500 V between the sleeve and the counter electrode, and connect both ends of the 1 MΩ and 10 KΩ resistors in series. Measure the voltage drop and calculate the current value from this value.
[0179]
(4) Measurement of toner particle size (weight average particle size)
The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter). In the present invention, the number distribution is obtained using a Coulter Multisizer (manufactured by Coulter). , An interface for outputting volume distribution (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) are connected, and 1% NaCl aqueous solution is prepared using first-grade sodium chloride as the electrolyte. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte solution in which the sample is suspended is subjected to a dispersion process for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toners of 2 μm or more are measured using the 100 μm aperture as an aperture by the Coulter Multisizer. The number distribution was calculated. Then, the volume-based volume average particle diameter (D_v: The median value of each channel is the representative value of the channel) and the weight average particle diameter (D_Four), The number average length average particle diameter (D₁) And a volume-based particle ratio (8.00 μm and 3.17 μm or less) obtained from the volume distribution) and a number-based particle ratio (5 μm or less and 3.17 μm or less) obtained from the number distribution.
[0180]
(5) Measurement of weight average particle diameter of external additive (inorganic fine powder)
The measuring apparatus uses a Microtrac particle size analyzer Model 9230UPA (manufactured by Nikkiso Co., Ltd.) and measures as follows.
1) Put 20 ml of ethanol in a 50 cc glass beaker.
2) Add the sample so that the Reflected Power is 200 mV.
3) Disperse with an ultrasonic generator UD200 (manufactured by Tommy Seiko Co., Ltd.) for 3 minutes.
4) Take 6 ml of the sample dispersion, measure 3 times under the temperature condition of 22 ° C., calculate the weight average particle size from the volume particle size distribution, and take the average value.
[0181]
(6) Measurement of hydrophobicity of inorganic fine powder
The methanol measurement test is an experimental test for confirming the degree of hydrophobicity of an inorganic fine powder having a hydrophobized surface.
[0182]
In order to evaluate the degree of hydrophobicity of the treated inorganic fine powder, the “methanol titration test” defined in this specification is performed as follows.
[0183]
0.2 g of the test inorganic fine powder is added to 50 ml of water in a 250 ml Erlenmeyer flask. Methanol is titrated from the burette until all of the inorganic fine powder is wet. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed by suspending the total amount of inorganic fine powder in the liquid, and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.
[0184]
(7) Measurement of light transmittance
▲ 1 ▼ Sample 0.10g
Alkyd resin 13.20g
(Dec Nippon Beccosol 1323-60-EL)
Melamine resin 3.30g
(Dainippon Ink Super Bekkamin J-820-60)
Thinner 3.50g
(Aramic thinner made by Kansai Paint)
Glass media 50.00g
[0185]
The above composition is collected in a 150 cc glass bottle and dispersed for 1 hour in a paint conditioner manufactured by Red Devil.
[0186]
(2) After the dispersion, the distance between the surface of the PET film and the doctor blade is set to 2 mm, and the dispersion is applied to the PET film.
[0187]
(3) (2) is heated at 120 ° C. for 10 minutes to be baked.
[0188]
(4) The light transmittance of the sheet (3) was measured in the range of 320 to 800 nm with U-BEST 50 manufactured by JASCO Corporation.
[0189]
(8) Measurement of specific surface area
The following procedure is performed using a Shimadzu powder specific surface area measuring apparatus (SS-100 type).
1) Turn on the power of the powder tester's auto slider for adjusting the sample iron powder to 100V.
2) Tap the passer tester switch and adjust the timer to 1 minute (50 ± 1 / minute).
3) Put a sieve plate in a plastic sample tube, place a sheet of filter paper on it, and put the sample up to 1/3 of the sample tube on it.
4) Set the sample tube on the powder tester's tap mount, and press the start button (tap for 1 minute).
5) Further, put the sample into the tapped sample cylinder up to 2/3 of the sample cylinder.
6) Perform the same operation as in item 4 above.
7) Insert a supplementary cylinder (plastic) on top of the sample cylinder and place the sample on top of it.
8) Perform the same work as items 4 and 6 above.
9) Remove the tapped sample tube from the tap mount, remove the supplementary tube, and cut the excess sample with a spatula.
10) Fill water up to the S scale of the specific surface area measuring tube.
11) Connect the sample tube to the measuring tube (after filling the sample, apply grease to the rubbing surface).
12) Open the cock at the lower outlet and start the stopwatch when the water level of the measuring tube passes the 0 scale (receive the lower effluent in a beaker).
13) Measure the time for the water level to drop to 20 scales (unit is cc).
14) Remove the sample tube and measure the weight of the sample.
15) Calculation of specific surface area
[0190]
The specific surface area is calculated by the following formula.
[0191]
[Expression 1]

[0192]
SW: Specific surface area of powder cm²/ G
e: Porosity of sample packed bed
ρ: density of powder g / cm²
η: Fluid viscosity coefficient g / cm · sec
L: thickness of sample layer cm
Q: Sample layer permeating fluid amount cc
ΔP: Pressure difference between both ends of sample layer g / cm²
A: Cross-sectional area of sample layer cm²
t: Time required for the Qcc fluid (air) to pass through the sample layer sec
W: Weight of sample g
[0193]
(9) Measurement of carrier density
Using AccuPick 1330 made by Shimadzu Corporation, carrier is 10cm²Fill the container for about 8 minutes with very light tapping in the measurement cell, dry it with a vacuum dryer set at 40 ° C for 24 hours, measure the weight, insert it into the main body, and fill with helium gas After purging the pressure ten times at 134.45 KPa, the average value measured five times at a filling pressure of 134.45 KPa and an equilibrium pressure of 0.0345 KPa was taken as the carrier density.
[0194]
(10) Acid value measurement method
2-10 g of sample is weighed into a 200-300 ml Erlenmeyer flask and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is added to dissolve the resin. If solubility is poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, titration is performed with a pre-standardized N / 10 caustic potash to alcohol solution, and the acid value is obtained from the consumption of the alcohol potash solution by the following calculation.
[0195]
Acid value = KOH (ml) x N x 56.1 / sample weight
(N is a factor of N / 10KOH)
[0196]
(11) Measurement of glass transition temperature Tg
In this invention, it measures using a differential thermal analysis measuring device (DSC measuring device) and DSC-7 (made by Perkin Elmer).
[0197]
The sample to be measured is precisely weighed 5 to 20 mg, preferably 10 mg.
[0198]
This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise rate of 10 ° C./min at room temperature and humidity in a measurement temperature range of 30 ° C. to 200 ° C.
[0199]
In this temperature raising process, an endothermic peak of the main peak in the temperature range of 40 to 100 ° C. is obtained.
[0200]
At this time, the point of intersection between the intermediate line of the baseline and the differential heat curve before and after the endothermic peak appears is defined as the glass transition temperature Tg in the present invention.
[0201]
(12) Softening point temperature (Tm)
A flow tester CFT-500 type (manufactured by Shimadzu Corporation) is used. The sample weighs about 1.0 g of a 60 mesh pass product. Using a molding machine, 100 kg / cm²Apply pressure for 1 minute.
[0202]
The pressure sample is subjected to flow tester measurement at room temperature and normal humidity (temperature of about 20 to 30 ° C., humidity of 30 to 70% RH) under the following conditions to obtain a temperature-apparent viscosity curve. From the obtained smooth curve, the temperature (= T_1/2), And this is defined as the softening point temperature (Tm).
[0203]
RATE TEMP 6.0 D / M (℃ 1 minute)
SET TEMP 50.0 DEG (℃)
MAX TEMP 180.0 DEG
INTERVAL 3.0 DEG
PREHEAT 300.0 SEC (seconds)
LOAD 20.0 KGF (kg)
DIE (DIA) 1.0 MM (mm)
DIE (LENG) 1.0 MM (mm)
PLUNGER 1.0 CM²(Cm²)
[0204]
【Example】
Although the Example of this invention is shown below, this invention is not limited to this at all. “Parts” means “parts by weight”.
[0205]
(Production Examples 1 to 3 of magnetic carrier core particles)
20 parts MgO (solubility 0.62 mg / 100 ml), 20 parts MnO, Fe₂O_Three  After 60 parts were atomized, water was added and mixed, granulated, fired at 1100 ° C. and adjusted for particle size as shown in Table 1, and then average particle sizes of 35.7 μm, 25.6 μm and 61. 3 μm ferrite carrier core particles (saturation magnetization 58 Am²/ Kg) A, B and C were obtained respectively.
[0206]
(Production Example 4 of Magnetic Carrier Core Particles)
MgO 15 parts, NiO 10 parts, Al₂O_Three  3 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 36.3 μm (saturated magnetization 60 Am), except that 72 parts are used²/ Kg) D was obtained.
[0207]
(Production Example 5 of Magnetic Carrier Core Particles)
Ag₂3 parts of O (solubility 1.74 mg / 100 ml), 27 parts of MnO, Fe₂O_Three  Ferrite carrier core particles having an average particle diameter of 39.3 μm (saturation magnetization 65 Am), except that 70 parts are used²/ Kg) E was obtained.
[0208]
(Manufacturing Example 6 of Magnetic Carrier Core Particles)
BaO (solubility 1 g or more / 100 ml) 20 parts, ZnO 20 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 36.0 μm (saturation magnetization 57 Am) except that 60 parts are used in the same manner as in Production Example 1.²/ Kg) F was obtained.
[0209]
(Production Example 7 of Magnetic Carrier Core Particles)
K₂5 parts of O (solubility 1 g or more / 100 ml), 20 parts of NiO, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 36.8 μm (saturation magnetization 55 Am), except that 73 parts are used²/ Kg) G was obtained.
[0210]
(Production Example 8 of Magnetic Carrier Core Material Particles)
MgO (solubility 0.62mg / 100ml) 35 parts, MnO 5 parts, Fe₂O_ThreeFerrite carrier core particles having an average particle size of 37.5 μm (saturation magnetization 47 Am), except that 60 parts are used²/ Kg) H was obtained.
[0211]
(Production Example 9 of Magnetic Carrier Core Material Particles)
MgO (solubility 0.62mg / 100ml) 0.002 parts, MnO 25 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle diameter of 35.5 μm (saturation magnetization 63 Am), except that 74.998 parts are used²/ Kg) I was obtained.
[0212]
(Manufacturing Example 10 of Magnetic Carrier Core Particles)
10 parts of MgO (solubility 0.62 mg / 100 ml), 80 parts of MnO, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 35.8 μm (saturation magnetization 15 Am) except that 10 parts are used²/ Kg) J was obtained.
[0213]
(Manufacturing Example 11 of Magnetic Carrier Core Material Particles)
MgO (solubility 0.62mg / 100ml) 25 parts, MnO 0 parts, Fe₂O_ThreeAlthough it carried out similarly to manufacture example 1 except using 75 parts, particle coalescence was intense and the carrier particle was not obtained.
[0214]
(Production Example 12 of Magnetic Carrier Core Material Particles)
20 parts of MgO (solubility 0.62 mg / 100 ml), 65 parts of MnO, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 36.3 μm (saturation magnetization 20 Am), except that 15 parts are used²/ Kg) K was obtained.
[0215]
(Manufacturing Example 13 of Magnetic Carrier Core Particles)
3 parts of MgO (solubility 0.62 mg / 100 ml), 1 part of MnO, Fe₂O_Three  Ferrite carrier core particles having an average particle diameter of 38.5 μm (saturation magnetization of 70 Am) except that 96 parts are used²/ Kg) L was obtained.
[0216]
(Carrier Production Examples 1 to 7)
Take 20 parts of toluene, 20 parts of butanol, 20 parts of water and 40 parts of ice in a four-necked flask and mix with stirring._ThreeSiCl_Three  15 moles and (CH_Three)₂SiCl₂  After adding 40 parts of a mixture with 10 mol and further stirring for 30 minutes, a condensation reaction was carried out at 60 ° C. for 1 hour. Thereafter, the siloxane was thoroughly washed with water and dissolved in a toluene-methyl ethyl ketone-butanol mixed solvent to prepare a silicone varnish having a solid content of 10%.
[0217]
To this silicone varnish, 2.0 parts of ion-exchanged water and 2.0 parts of the following curing agent for 100 parts of siloxane solids
[0218]
[Chemical 8]

And 3.0 parts of the following aminosilane coupling agent
[0219]
[Chemical 9]

Were simultaneously added to prepare carrier coating solution I.
[0220]
This coating solution I was applied to 100 parts A to G of the above-described magnetic carrier core material particles with a coating machine (Okada Seiko Co., Ltd .: Spiracoater) so that the resin coating amount was 1.0 part. 7 was obtained.
[0221]
(Carrier Production Example 8)
The aminosilane coupling agent used in Carrier Production Example 1 is the following aminosilane coupling agent.
[0222]
Embedded image

A coated carrier 8 was obtained in the same manner as in Production Example 1 of the carrier except that the resin solution (II) changed to 1 was used.
[0223]
(Carrier production example 9)
A coated carrier 9 was obtained in the same manner as in Carrier Production Example 1 except that the coating solution (III) not using the siloxane and the curing agent used in Carrier Production Example 1 was used.
[0224]
(Carrier Production Example 10)
A coated carrier 10 was obtained in the same manner as in Carrier Production Example 1 except that the resin solution (IV) not using the anomisilane coupling agent used in Carrier Production Example 1 was used.
[0225]
(Carrier Production Examples 11 to 15)
The coated carrier 11 is the same as the carrier production examples 1 to 7 except that the magnetic carrier core material particles H to L are used instead of the magnetic carrier core material particles A to G used in the carrier production examples 1 to 7. ~ 15 were obtained respectively.
[0226]
Table 1 shows the physical properties of the carriers 1 to 15 obtained above.
[0227]
[Table 1]

[0228]
(Toner Production Example 1)
100 parts of propoxylated bisphenol and fumaric acid
Polyester resin obtained by condensation
Phthalocyanine pigment 4 parts
4 parts of chromium complex of di-tert-butylsalicylic acid
[0229]
The above raw materials are sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, cooled and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet fine pulverizer. Crushed. Further, the obtained finely pulverized product was classified to obtain black powder (toner particles) having a weight average particle diameter of 5.8 μm.
[0230]
100 parts of the above black powder and n-C in an aqueous medium_FourH₉-Si- (OCH_Three)_ThreeOf anatase-type titanium oxide fine powder having a weight average particle size of 0.05 μm, a hydrophobization degree of 55% and a light transmittance of 70%. Were mixed with a Henschel mixer to obtain cyan toner a.
[0231]
(Toner Production Example 2)
The anatase-type titanium oxide fine powder used in Toner Production Example 1 is treated as it is without being sintered, and has a weight average particle size of 0.0008 μm, a hydrophobicity of 50%, and a light transmittance of 70%. A cyan toner b was obtained in the same manner as in Toner Production Example 1 except that the titanium compound was used.
[0232]
(Toner Production Example 3)
Except that the anatase-type titanium oxide fine powder used in Toner Production Example 1 was replaced with 20% rutile titanium oxide for pigments having a weight average particle size of 0.4 μm, a hydrophobization degree of 70% and a light transmittance of 20%. Thus, cyan toner c was obtained in the same manner as in Toner Production Example 1.
[0233]
(Toner Production Example 4)
Fine particles of titanium oxide having a weight average particle diameter of 0.05 μm, a hydrophobization degree of 65% and a light transmittance of 65% by further treating the anatase-type titanium oxide fine powder used in Toner Production Example 1 with 100 cp of dimethyl silicone oil. A cyan toner d was obtained in the same manner as in Toner Production Example 1 except that
[0234]
(Toner Production Example 5)
The anatase-type titanium oxide fine powder used in Toner Production Example 1 is treated with 100 cp dimethyl silicone oil in the gas phase to have a weight average particle size of 0.02 μm, a hydrophobicity of 90%, and a light transmittance of 35%. A cyan toner e was obtained in the same manner as in Toner Production Example 1 except that the silica fine particles were replaced.
[0235]
Example 1
The above-mentioned cyan toner a and carrier 1 are mixed at a toner concentration of 7% to prepare a two-component developer, and using a color copying machine CLC700 (manufactured by Canon) using an alternating electric field shown in FIG. Using an original document with an image area ratio of 25% at 300V, 10,000 images were printed at 23 ° C / 65% RH, 30 ° C / 80% RH, and 20 ° C / 10% RH. The results are shown in Table 2. From Table 2, it can be seen that the above-mentioned two-component developer has very little fluctuation in the printing durability test, and the scattering after 10,000 sheets is satisfactory without any problem.
[0236]
Example 2
A two-component developer was prepared in the same manner as in Example 1 except that the carrier 2 shown in Table 1 was used instead of the carrier 1 used in Example 1 and the toner concentration was 9%. Evaluation was performed in the same manner. The results are shown in Table 2.
[0237]
Reference example 1
A two-component developer was prepared in the same manner as in Example 1 except that the carrier 3 shown in Table 1 was used instead of the carrier 1 used in Example 1 and the toner concentration was 5%. Evaluation was performed in the same manner. The results are shown in Table 2.
[0238]
Examples 3 to 5 and Reference Example 2
A two-component developer in the same manner as in Example 1 except that instead of the carrier 1 used in Example 1, the carriers 4, 5, 8 and 10 shown in Table 1 are used as shown in Table 2, respectively. Table 2 shows the results of the preparation and evaluation in the same manner.
[0239]
Comparative Examples 1-3
A two-component developer is prepared in the same manner as in Example 1 except that instead of the carrier 1 used in Example 1, the carriers 6, 7 and 9 shown in Table 1 are used as shown in Table 2, respectively. Table 2 shows the results of similar evaluation.
[0240]
Comparative Examples 4-9
A two-component developer was prepared in the same manner as in Example 1 except that instead of the carrier 1 used in Example 1, the carriers 11 to 15 shown in Table 1 were used as shown in Table 2, respectively. Table 2 shows the results of similar evaluation.
[0241]
[Table 2]

[0242]
(Carrier Production Examples 16 and 17)
In Carrier Production Example 1, coated carriers 16 and 17 were obtained in the same manner as in Carrier Production Example 1 except that the amount of ion-exchanged water added was changed to 0 part and 7 parts.
[0243]
Example 6
Except that the carrier 16 was used, the evaluation was performed in the same manner as in Example 1. As a result, the fog was slightly deteriorated to 1.5% at 20 ° C./10% RH, but the durability was low. Declined. This is presumed to be because the resin coating was not sufficiently performed because water was not used.
[0244]
Example 7
Except that the carrier 17 was used, the evaluation was performed in the same manner as in Example 1. As a result, although the level was practically no problem, when the toner concentration was at the upper limit of the control range, the toner was slightly scattered at 30 ° C./80% RH. There has occurred. This is presumably because the self-crosslinking of the resin progressed excessively due to the large amount of water used, and the adhesion to the surface of the carrier core material slightly decreased.
[0245]
Example 8
A two-component developer was prepared in the same manner as in Example 1 except that the toner b was used in place of the toner a used in Example 1, and the initial image quality was good when evaluated in the same manner. However, the uniformity of the solid at 20 ° C./10% RH slightly decreased, and the fog slightly deteriorated to 1.6%.
[0246]
Example 9
A two-component developer was prepared in the same manner as in Example 1 except that the toner c was used in place of the toner a used in Example 1, and evaluated in the same manner. As a result, 30 ° C./80% RH was obtained. A slight amount of toner scattering occurred below. In addition, the fog decreased to 1.7%.
[0247]
Example 10
A two-component developer was prepared in the same manner as in Example 1 except that the toner d was used instead of the toner a used in Example 1, and the fog was 0.9%. However, although the uniformity of the solid at 20 ° C./10% RH was slightly lowered, good results were obtained.
[0248]
Reference example 3
A two-component developer was prepared in the same manner as in Example 1 except that the toner e was used in place of the toner a used in Example 1, and evaluated in the same manner. However, the uniformity of the solid content was slightly lowered and the fog was slightly deteriorated to 1.5% at 30 ° C./80% RH, but good results were obtained.
[0249]
Example 11
Using a two-component developer in which the toner a and the coating carrier 1 used in Example 1 are combined, and using the image forming apparatus shown in FIG. 1, the developing sleeve has a five-pole configuration having a developing main pole of 960 gauss. Built-in magnet roller, superimpose the alternating electric field of FIG._cont= 230V, V_back= -130 V was set, and the image-drawing test was conducted at a temperature / humidity of 23 ° C./60% RH.
[0250]
As a result, even after the endurance of 10,000 sheets, 1.0% fogging and solid uniformity under 20 ° C./10% RH were obtained with no problem and very good results were obtained.
[0251]
Example 12
An image formation test was performed in the same manner as in Example 11 except that the alternating electric field shown in FIG. 3 was used instead of the alternating electric field used in Example 11.
[0252]
As a result, the uniformity of the solid at 20 ° C./10% RH was slightly lowered and the fog was slightly lowered to 1.4%, but good results were obtained.
[0253]
Example 13
An image formation test was performed in the same manner as in Example 11 except that the alternating electric field shown in FIG. 5 was used instead of the alternating electric field used in Example 11.
[0254]
As a result, good results were obtained although the solid uniformity under 20 ° C./10% RH was slightly reduced.
[0255]
(Manufacturing Example 14 of Magnetic Carrier Core Material Particles)
20 parts MgO (solubility 0.62 mg / 100 ml), 20 parts MnO, Fe₂O_Three  After atomizing 60 parts each, adding and mixing water, granulating, firing at 1100 ° C. and adjusting the particle size as shown in Table 3, ferrite core particles (average particle size 35.7 μm) ( Saturation magnetization 58Am²/ Kg) M was obtained.
[0256]
(Manufacturing Example 15 of Magnetic Carrier Core Particles)
MgO 15 parts, MnO 15 parts, SiO₂  3 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 38.3 μm (saturated magnetization 60 Am), except that 67 parts are used and fired at 1300 ° C.²/ Kg) N was obtained.
[0257]
(Manufacturing Example 16 of Magnetic Carrier Core Particles)
MgO 3 parts, Li₂O 5 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle diameter of 40.5 μm (saturation magnetization 57 Am) except that 92 parts are used²/ Kg) O was obtained.
[0258]
(Production Example 17 of magnetic carrier core material particles)
MgO 20 parts, Al₂O_Three  5 parts, Fe₂O_Three  Ferrite carrier core particles having an average particle size of 43.2 μm (saturation magnetization 57 Am), except that 75 parts are used²/ Kg) P was obtained.
[0259]
(Carrier Production Examples 18-21)
Instead of the magnetic carrier core particles A to G used in Carrier Production Examples 1 to 7, the magnetic carrier core particles MP are used, and the resin coating amount of the coating solution I is changed to 0.5% by weight. In the same manner as in Carrier Production Examples 1 to 7, coated carriers 18 to 21 were obtained.
[0260]
(Carrier Production Example 22)
50 parts of a styrene-2-ethylhexyl acrylate-methyl methacrylate (50:20:30) copolymer and 50 parts of a vinylidene fluoride-tetrafluoroethylene (50:50) copolymer are mixed and mixed in a toluene-methyl ethyl ketone mixed solvent. A coated carrier 22 was obtained in the same manner as in Production Examples 16 to 19 except that the coating solution V was dissolved and applied.
[0261]
Table 3 shows the physical properties of the carriers 18 to 22 obtained above.
[0262]
[Table 3]

[0263]
(Polyester resin synthesis example 1)
Polyoxypropylene (2.2) -2,2bis 45 mol%
(4-Hydroxyphenyl) propane
Polyoxyethylene (2) -2,2-bis 6mol%
(4-Hydroxyphenyl) propane
Fumaric acid 47mol%
Trimellitic anhydride 2 mol%
[0264]
Dibutyltin oxide is added to the above raw material as a catalyst, a condensation polymerization reaction is performed at 200 ° C. under a nitrogen stream, and the reaction is terminated when a softening point of 92 ° C. according to ASTM E28-51T is reached. )
[0265]
The acid value of the resin was 9.5 KOH mg / g, and the glass transition temperature was 57.2 ° C.
[0266]
(Polyester resin synthesis example 2)
Polyoxypropylene (2.2) -2,2bis 45 mol%
(4-Hydroxyphenyl) propane
Polyoxyethylene (2) -2,2-bis 4mol%
(4-Hydroxyphenyl) propane
Fumaric acid 40mol%
Terephthalic acid 10mol%
Trimellitic anhydride 1 mol%
[0267]
Dibutyltin oxide was added to the above raw material as a catalyst, and a condensation polymerization reaction was performed at 200 ° C. under a nitrogen stream. When the softening point 91 ° C. according to ASTM E28-51T was reached, the reaction was terminated. )
[0268]
The acid value of the resin was 22.0 KOHmg / g, and the glass transition temperature was 55.3 ° C.
[0269]
(Polyester resin synthesis example 3)
Polyoxypropylene (2.2) -2,2bis 45 mol%
(4-Hydroxyphenyl) propane
Polyoxyethylene (2) -2,2-bis 10mol%
(4-Hydroxyphenyl) propane
Fumaric acid 43mol%
1,2,5-hexanetricarboxylic acid 2 mol%
[0270]
Dibutyltin oxide is added to the above raw material as a catalyst, a condensation polymerization reaction is performed at 200 ° C. under a nitrogen stream, and the reaction is terminated when a softening point of 95 ° C. according to ASTM E28-51T is reached. )
[0271]
The acid value of the resin was 0.8 KOHmg / g, and the glass transition temperature was 58.1 ° C.
[0272]
(Polyester resin synthesis example 4)
Polyoxypropylene (2.2) -2,2bis 49 mol%
(4-Hydroxyphenyl) propane
Terephthalic acid 49mol%
2,5,7-Naphthalenetricarboxylic acid 2 mol%
[0273]
Dibutyltin oxide is added to the above raw material as a catalyst, a condensation polymerization reaction is performed at 200 ° C. under a nitrogen stream, and the reaction is terminated when a softening point of 92 ° C. according to ASTM E28-51T is reached. )
[0274]
The acid value of the resin was 17.1 KOHmg / g, and the glass transition temperature was 57 ° C.
[0275]
(Polyester resin synthesis example 5)
Polyoxypropylene (2.2) -2,2bis 53 mol%
(4-Hydroxyphenyl) propane
Fumaric acid 45mol%
1,2,7,8-octanetetracarboxylic acid 2 mol%
[0276]
Dibutyltin oxide is added to the above raw material as a catalyst, and a polycondensation reaction is performed at 200 ° C. under a nitrogen stream. When the softening point reaches 95 ° C. according to ASTM E28-51T, the reaction is terminated. )
[0277]
The acid value of the resin was 2.2 KOHmg / g, and the glass transition temperature was 59 ° C.
[0278]
(Polyester resin synthesis example 6)
Polyoxypropylene (2.2) -2,2bis 50 mol%
(4-Hydroxyphenyl) propane
Terephthalic acid 49.5 mol%
Trimellitic anhydride 0.5 mol%
[0279]
Dibutyltin oxide is added to the above raw material as a catalyst, a condensation polymerization reaction is performed at 200 ° C. under a nitrogen stream, and the reaction is terminated when a softening point of 103 ° C. according to ASTM E28-51T is reached. )
[0280]
The acid value of the resin was 8.7 KOHmg / g, and the glass transition temperature was 61 ° C.
[0281]
(Toner Production Example 7)
100 parts of propoxylated bisphenol, fumaric acid and trimellitic acid
Polyester resin obtained by condensation of trimellitic acid (I)
Phthalocyanine pigment 4 parts
Di-tert-butylsalicylic acid metal complex 4 parts
[0282]
The above is sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, cooled and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet type pulverizer. did. Further, the obtained finely pulverized product was classified to obtain a blue powder having a weight average particle diameter of 5.8 μm.
[0283]
Iso-C in 100 parts of the above colored powder and water / butanol mixed medium_FourH₉-Si- (OCH_Three)_ThreeWas mixed with a Henschel mixer to obtain an average particle size of 0.02 μm of alumina fine powder treated with 20 parts and 1.5 parts of hydrophobicity of 65% to obtain cyan toner f.
[0284]
The toner had an acid value of 9.5 KOH mg / g, Tm of 90 ° C. and Tg of 55 ° C.
[0285]
(Toner Production Example 8)
In Toner Production Example 7, n-C was used in an aqueous medium instead of alumina._FourH₉-Si- (OCH_Three)_ThreeA cyan toner g was obtained in the same manner as in Toner Production Example 7 except that titanium oxide fine powder (average particle size 0.03 μm, hydrophobicity 60%) treated with 25 parts of was used.
[0286]
This toner had the same acid value, Tm and Tg as toner f.
[0287]
(Toner Production Examples 9 to 13)
Toners h to l shown in Table 4 were obtained in the same manner except that polyester resins (II) to (VI) were used in place of the polyester resin (I) used in Toner Production Example 7.
[0288]
Table 4 shows the constitution and physical properties of the toners f to l obtained above.
[0289]
[Table 4]

[0290]
Examples 14 and 15
The above-mentioned cyan toners f and g and the carrier 18 are mixed at a toner concentration of 7% to prepare a two-component developer, and a color copier CLC700 (manufactured by Canon) is used to protect the electrostatic latent image holding member in the protective layer. The electrostatic latent image carrier (I) containing 30% by weight of fluorine atom-containing resin particles, and a non-continuous electric field shown in FIG. 4 as an alternating electric field was applied, and the development contrast was 300 V and the original image area ratio was 25%. Table 5 shows the results of printing 10,000 sheets using a manuscript at 23 ° C./65% RH, 30 ° C./80% RH, and 20 ° C./10% RH.
[0291]
Examples 16-19
Table 5 shows the results of image output in the same manner as in Examples 14 and 15 except that cyan toners h to k were used instead of cyan toners f and g used in Examples 14 and 15. . In Examples 16 and 17 using the toner h having a high acid value and the toner j having a low acid value, although the toner scattering was slightly worse than those in Examples 14 and 15, the level was not problematic in practical use.
[0292]
Example 20
Table 5 shows that the image gloss was lowered and the image density was slightly lowered when the same procedure as in Examples 14 and 15 was performed except that the toner l was used instead of the toners f and g used in Examples 14 and 15. As shown in the figure, good results were obtained.
[0293]
Examples 21-23
Except that the carriers 19 to 21 were used in place of the carrier 18 used in Examples 14 and 15, images were drawn in the same manner as in Examples 14 and 15, and good results were obtained as shown in Table 5. It was.
[0294]
Reference example 4
Except for using the carrier 22 in place of the carrier 18 used in Examples 14 and 15, the image was printed out in the same manner as in Examples 14 and 15, but the coating material was not a silicone resin, so it was slightly durable. However, as shown in Table 5, good results were obtained.
[0295]
Examples 24-26
Instead of the electrostatic latent image carrier (I) used in Examples 14 and 15, the content of fluorine atom-containing resin particles in the protective layer of the electrostatic latent image carrier is 20%, 6%, and 0%, respectively. Table 5 shows the results obtained in the same manner as in Examples 14 and 15 except that the changed electrostatic latent image carriers (II) to (IV) were used. As the fluorine atom-containing resin particle content decreases, the solid uniformity is slightly deteriorated, but there is no practical problem.
[0296]
Examples 27 and 28
When it carried out similarly to Example 14 and 15 except using the alternating electric field shown in FIG.5 and FIG.2 instead of the alternating electric field used in Examples 14 and 15, respectively, a favorable result was shown as shown in Table 5. Obtained.
[0297]
Example 29
In place of the alternating electric field used in Examples 14 and 15, except that the continuous electric field shown in FIG. 3 was used as the alternating electric field, the same operation as in Examples 14 and 15 was performed. Although the uniformity was also slightly deteriorated, as shown in Table 5, it was a level with no practical problem.
[0298]
[Table 5]

[0299]
In the above examples, image density, fog, durability (toner spent), toner scattering, and solid uniformity were evaluated based on the following evaluation methods.
[0300]
[Image density]
The density was measured with a reflection densitometer RD918 (manufactured by Macbeth).
[0301]
A: Excellent 1.6 to 1.7
○: Good 1.7 to 1.8, less than 1.45 to 1.6
Δ: Possible Over 1.8 to 1.9, less than 1.3 to 1.45
×: Impossible More than 1.9, less than 1.3
[0302]
[Fog]
The evaluation of fog is made by Tokyo Denshoku REFECTOMETER MODEL
Measurement was performed using TC-6DS, and an amber filter was used for a cyan toner image and was calculated from the following equation. The smaller the value, the less fog.
[0303]
Fog (reflectance) (%) = reflectance of standard paper (%) − reflectance of non-image part of sample (%)
[0304]
A: 0 to 1.2%
○: Over 1.2% to 1.6%
Δ: Over 1.6% to 1.9%
×: Over 1.9%
[0305]
[Toner spent]
Observe at 2,000 times with a scanning electron microscope.
[0306]
◎ Toner spent is not recognized and the charge level is not lowered.
○ Some toner spent is observed, but the charge amount is not lowered.
Δ: A lot of toner spent is observed in the recess, but the change in the charge amount is small.
X Toner spent is recognized throughout and the change in charge amount is large.
[0307]
[Toner scattering]
Toner scattering was evaluated based on the following evaluation criteria by observing dirt on the outer surface of the upstream toner scattering suppression portion and downstream toner scattering suppression portion of the developing container and toner contamination other than the developing container.
[0308]
◎ Not recognized at all.
○ Some dirt is observed on the outer surface of the upstream toner scattering suppression portion of the developing container, but no dirt is observed on the outer surface of the downstream toner scattering suppression portion.
Δ: Contamination is observed on the outer surface of the upstream toner scatter suppression portion and the outer surface of the downstream toner scatter prevention portion of the developing container, but no contamination is observed except for the developing container.
× Dirt is observed except for the developing container.
[0309]
[Solid uniformity]
◎ With CLC-SK paper, there is no problem with paper left for one week.
○ CLC-SK paper can be left undisturbed for 3 days.
△ CLC-SK paper can be left overnight for no problem.
X CLC-SK paper is uneven when left overnight.
[0310]
【The invention's effect】
In the carrier of the present invention and the two-component developer using the carrier, the carrier is coated with a resin coating layer on the surface of magnetic carrier core particles formed of a specific ferrite component, so that a color original having a large image area can be obtained. Even if continuous copying is performed, image density lowering and fogging are unlikely to occur, toner and carrier frictional charging can be quickly started, and a clear image without fogging can be maintained until after the endurance of many sheets. In addition, the triboelectric charging characteristic is less dependent on the environment, and further, the transportability in the developing device is good.
[Brief description of the drawings]
FIG. 1 is a schematic view of an image forming apparatus used in an image forming method of the present invention.
2 is a diagram showing an alternating electric field used in Example 1. FIG.
3 is a diagram showing an alternating electric field used in Example 12. FIG.
4 is a diagram showing an alternating electric field used in Example 11. FIG.
5 is a diagram showing an alternating electric field used in Example 13. FIG.
FIG. 6 is a view showing a preferred embodiment of an electrostatic latent image holding member that can be used in the image forming method of the present invention.
FIG. 7 is a diagram showing another example of an image forming apparatus used in the image forming method of the present invention.

Claims (14)

A toner including at least toner particles and hydrophobized alumina microparticles or hydrophobized titanium oxide microparticles; and a carrier having a magnetic carrier core material particle and a resin coating layer covering the magnetic carrier core material particle In a two-component developer,
The carrier core particles are represented by the following formula (I)
(Fe ₂ O ₃ ) _x (A) _y (B) _z formula (I)
[In the formula, A represents MgO, Ag ₂ O or a mixture thereof; B represents Li ₂ O, MnO, CaO, SrO, Al ₂ O ₃ , SiO ₂ or a mixture thereof; x, y and z represents a weight ratio and the following conditions 0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3,
0 <z ≦ 0.795, x + y <1, z = 1−xy
Satisfied. ]
It is formed with a magnetic ferrite component indicated by
The resin coating layer comprises an aminosilane coupling agent and the following formula (III)

A resin coating layer formed from a reactive silicone resin containing a curing agent represented by
The carrier has a specific surface area S ₁ calculated by the air permeation method and a specific surface area S ₂ calculated from the following formula (II).
S ₂ = [6 / (ρ · D ₅₀ )] × 10 ⁴ formula (II)
[Wherein ρ represents the density of the carrier, and D ₅₀ represents the 50% particle size of the carrier. ]
The two-component developer characterized in that the ratio (S ₁ / S ₂ ) is 1.3 to 1.8. 2. The two-component developer according to claim 1, wherein the carrier core material particles contain 0.5 to 30 wt% of MgO in terms of oxide. B in formula (I) are, MnO, CaO, two-component developer according to claim 1 or 2, characterized in that indicating the Al ₂ O _3, SiO ₂ or mixtures thereof. The carrier is in the presence of water, two-component developer according to any one of claims 1 to 3, characterized in that the reactive silicone resin is obtained by coating on the carrier core particles Agent. The two-component developer according to any one of claims 1 to 4 , wherein the carrier has a 50% particle size of 15 to 60 µm. The two-component developer according to any one of claims 1 to 5 , wherein the carrier has a particle size distribution containing 2 to 20% by weight of carrier particles of 62 µm or more. The carrier has a particle size distribution containing 1 to 20% by weight of carrier particles smaller than 22 μm, 2 to 20% by weight of carrier particles smaller than 16 μm, and 3% by weight or less of carrier particles of 88 μm or more. The two-component developer according to claim 6 . The carrier according to any one of claims 1 to 7, wherein the ratio ratio of the surface area S ₁ and the specific surface area _{S 2 (S 1 / S 2} ) is 1.4 to 1.7 two Component developer. The toner has a weight average particle diameter of 1 to 9 μm,
The two-component developer according to any one of claims 1 to 8 , wherein the alumina fine particles or titanium oxide fine particles have a weight average particle diameter of 0.001 to 0.2 µm. It said toner particles are contained a binder resin and a colorant, the binder resin, two-component developer according to any one of claims 1 to 9, characterized in that it comprises a polyester resin. The two-component developer according to any one of claims 1 to 10 , wherein the toner particles have an acid value of 2 to 18 KOHmg / g. The two-component developer circulates and conveys a two-component developer having toner and carrier by a developer carrier, and applies a development bias having a discontinuous AC component to the developer carrier. A developing electric field is formed in a developing area between the electrostatic latent image carrier and the developer carrier, and the electrostatic latent image held on the electrostatic latent image carrier is carried on the developer carrier. two-component developer according to any one of claims 1 to 11, characterized in that the two-component developer for use in an image forming method of developing with a toner of the two-component developer are. A two-component developer having toner and a carrier is circulated and conveyed by a developer carrier, and a developing bias having a discontinuous AC component is applied to the developer carrier to thereby develop the electrostatic latent image carrier and the developer. An electrostatic latent image held on the electrostatic latent image carrier by forming a developing electric field in a development area between the developer carrier and the two-component developer carried on the developer carrier. An image forming method for developing with toner,
The toner includes at least toner particles and hydrophobized alumina fine particles or hydrophobized titanium oxide fine particles,
The carrier has carrier core particles and a resin coating layer covering the carrier core particles.
The carrier core particles are represented by the following formula (I)
(Fe ₂ O ₃ ) _x (A) _y (B) _z formula (I)
[In the formula, A represents MgO, Ag ₂ O or a mixture thereof; B represents Li ₂ O, MnO, CaO, SrO, Al ₂ O ₃ , SiO ₂ or a mixture thereof; x, y and z represents a weight ratio and the following conditions 0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3,
0 <z ≦ 0.795, x + y <1, z = 1−xy
Satisfied. ]
It is formed with a magnetic ferrite component indicated by
The resin coating layer comprises an aminosilane coupling agent and the following formula (III)

A resin coating layer formed from a reactive silicone resin containing a curing agent represented by
The carrier has a specific surface area S ₁ calculated by the air permeation method and a specific surface area S ₂ calculated from the following formula (II).
S ₂ = [6 / (ρ · D ₅₀ )] × 10 ⁴ formula (II)
[Wherein ρ represents the density of the carrier, and D ₅₀ represents the 50% particle size of the carrier. ]
Image forming method, wherein the ratio of (S ₁ / S ₂₎ is 1.3 to 1.8. The two-component developer, an image forming method according to claim 13, which is a two-component developer according to any one of claims 2 to 11.

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