JP3935273B2 - Image forming method - Google Patents

Description

〔式中、Ｒは、有機基を示す。〕
【００４５】
上記一般式（Ｉ）は様々な構造のものがあるが、例えば２価フェノールとカーボネート前駆体とを溶液法又は溶融法で反応せしめて製造されるあらゆる公知のポリカーボネートを使用することができ、一例を挙げれば下記一般式（ＩＩ）
【００４６】
【外２】

〔式中、Ｒ² は、水素原子、脂肪族炭化水素基、芳香族置換基であり、このＲ² が複数の場合、それらは同一であってもよいし、異なっていてもよく、ｍは、０〜４の数であり、Ｚは、単結合、脂肪族炭化水素基、芳香族置換基、−Ｓ−、−ＳＯ−、−ＳＯ₂ −、−Ｏ−又は−ＣＯ−で表わされる結合を示す。〕
で表わされる構造の繰返し単位を有する重合体が挙げられる。
【００４７】
このポリカーボネート樹脂は、様々なものを充当することができるが、通常は一般式（ＩＩＩ）〜（Ｖ）
【００４８】
【外３】

〔式中、Ｒ² は、水素原子、脂肪族炭化水素基、芳香族置換基であり、このＲ² が複数の場合、それらは同一であってもよいし、異なっていてもよく、ｍは、０〜４の数であり、Ｚは、単結合、脂肪族炭化水素基、芳香族置換基、−Ｓ−、−ＳＯ−、−ＳＯ₂ −、−Ｏ−又は−ＣＯ−で表わされる結合を示す。〕
で表わされる二価フェノールとホスゲンまたは炭酸エステル化合物の如きカーボネート前駆体とを反応させることによって容易に製造することができる。
【００４９】
すなわち、例えば、塩化メチレンの如き溶媒中において、公知の酸受容体や分子量調節剤の存在下、二価フェノールとホスゲンのようなカーボネート前駆体との反応により、あるいは二価フェノールとジフェニルカーボネートのようなカーボネート前駆体とのエステル交換反応によって製造される。
【００５０】
上記一般式（ＩＩＩ）〜（Ｖ）で表わされる二価フェノールとしては様々なものがあり、２，２−ビス（４−ヒドロキシフェニル）プロパン〔通称：ビスフェノールＡ〕をはじめ、例えば、ビス（４−ヒドロキシフェニル）メタン、ビス（４−ヒドロキシフェニル）フェニルメタン、ビス（４−ヒドロキシフェニル）ナフチルメタン、ビス（４−ヒドロキシフェニル）−（４−イソプロピルフェニル）メタン、ビス（３，５−ジメチル−４−ヒドロキシフェニル）メタン、１，１−ビス（４−ヒドロキシフェニル）エタン、１−ナフチル−１，１−ビス（４−ヒドロキシフェニル）エタン、１−フェニル−１，１−ビス（４−ヒドロキシフェニル）エタン、１，２−ビス（４−ヒドロキシフェニル）エタン、２−メチル−１，１−ビス（４−ヒドロキシフェニル）プロパン、２，２−ビス（３，５−ジメチル−４−ヒドロキシフェニル）プロパン、１−エチル−１，１−ビス（４−ヒドロキシフェニル）プロパン、２，２−ビス（３−メチル−４−ヒドロキシフェニル）プロパン、１，１−ビス（４−ヒドロキシフェニル）ブタン、２，２−ビス（４−ヒドロキシフェニル）ブタン、１，４−ビス（４−ヒドロキシフェニル）ブタン、２，２−ビス（４−ヒドロキシフェニル）ペンタン、４−メチル−２，２−ビス（４−ヒドロキシフェニル）ペンタン、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサン、２，２−ビス（４−ヒドロキシフェニル）ヘキサン、４，４−ビス（４−ヒドロキシフェニル）ヘプタン、２，２−ビス（４−ヒドロキシフェニル）ノナン、１，１０−ビス（４−ヒドロキシフェニル）デカン及び１，１−ビス（４−ヒドロキシフェニル）シクロデカンの如きジヒドロキシアリールアルカン類；ビス（４−ヒドロキシフェニル）スルホン及びビス（３，５−ジメチル−４−ヒドロキシフェニル）スルホンの如きジヒドロキシアリールスルホン類；ビス（４−ヒドロキシフェニル）エーテル及びビス（３，５−ジメチル−４−ヒドロキシフェニル）エーテルの如きジヒドロキシアリールエーテル類；４，４′−ジヒドロキシベンゾフェノン及び３，３′、５，５′−テトラメチル−４，４′−ジヒドロキシベンゾフェノールの如きジヒドロキシアリールケトン類；ビス（４−ヒドロキシフェニル）スルフィド、ビス（３−メチル−４−ヒドロキシフェニル）スルフィド及びビス（３，５−ジメチル−４−ヒドロキシフェニル）スルフィドの如きジヒドロキシアリールスルフィド類；ビス（４−ヒドロキシフェニル）スルホキシドの如きジヒドロキシアリールスルホキシド類；４，４′−ジヒドロキシジフェニルの如きジヒドロキシジフェニル類；ヒドロキノン、ゾルシノール及びメチルヒドロキノンの如きジヒドロキシベンゼン類；１，５−ジヒドロキシナフタレン、２，６−ジヒドロキシナフタレンの如きジヒドロキシナフタレン類が挙げられる。これらの二価フェノールは、それぞれ単独で用いてもよいし、２種以上を組み合わせて用いてもよい。
【００５１】
炭酸エステル化合物としては、ジフェニルカーボネートの如きジアリールカーボネート；及びジメチルカーボネート、ジエチルカーボネートの如きジアルキルカーボネート；が挙げられる。
【００５２】
本発明で使用されるポリカーボネート系樹脂は、これらの二価フェノールの１種を用いたホモポリマー２種以上を用いたコポリマー、もしくはブレンド物が用いられる。さらに、多官能性芳香族化合物を上記二価フェノール及び／又はカーボネート前駆体と反応させて得られる熱可塑性ランダム分岐ポリカーボネート樹脂であってもよい。
【００５３】
ポリカーボネート系樹脂のガラス転移温度や粘弾性を調節するために、上記の二価フェノールの一部をエチレングリコール、ジエチレングリコール、トリエチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，４−ブタンジオール、ネオペンチルグリコール、１，４−ビス（ヒドロキシメチル）シクロヘキサン、１，４−ビス（２−ヒドロキシエチル）ベンゼン、１，４−シクロヘキサンジメタノール、ポリエチレングリコール、プロピレングリコール、水素添加ビスフェノールＡおよびその誘導体、ビスフェノールＡのエチレンオキサイド付加物、ビスフェノールＡのプロピレンオキサイド付加物、グリセリン、トリメチロールプロパン、ペンタエリスリトールの如き多価アルコールに置き換えた形の変性ポリカーボネート系樹脂も好適に使用される。この場合、単純に二価フェノール類の一部と置き換えて前記した方法により製造することも可能であるが、他の製造方法の一例として、二価フェノールと脂肪族あるいは芳香族のビスクロロホルメートとをピリジンを触媒としてメチレンクロライド溶媒中で反応させる方法が例示されるが、もちろんその他の製造方法による合成も可能である。
【００５４】
さらに、本発明においてはポリカーボネート系樹脂として、上述したポリカーボネートとポリスチレン、スチレン−（メタ）アクリル共重合体、ポリエステル、ポリウレタン、エポキシ樹脂、ポリオレフィン、ポリアミド、ポリスルホン、ポリシアノアリールエーテル、ポリアリーレンスルフィドの如き他の重合体を合致するためのモノマーとのブロック共重合体やアルキル（メタ）アクリレートモノマー、（メタ）アクリル酸モノマー、マレイン酸モノマー、又はスチレン系モノマーをグラフトしたグラフト変性共重合体の使用も可能である。
【００５５】
本発明においては、トナー中のポリカーボネート系樹脂の含有量は特に制限されないが、結着樹脂全体の重量を基準として０．１〜５０重量％、好ましくは０．２〜４０重量％、より好ましくは０．３〜３０重量％、さらに好ましくは０．５〜３０重量％であることが良い。通常トナーは、高分子量樹脂や架橋樹脂と低分子量樹脂とを結着樹脂として併用することにより、トナーの粘弾性の設計を行って、低温および高温のオフセットを防止することが一般に行われているが、結着樹脂中のポリカーボネート系樹脂の含有量が５０重量％を超えてしまうと、この様な設計のトナーを製造することが困難となり、耐久性と定着性のバランスをとることが難しくなる。結着樹脂中のポリカーボネート系樹脂の含有量が０．１重量％未満であると、本発明の効果である優れた耐久性が得にくくなる。
【００５６】
本発明の画像形成方法におけるトナー用結着樹脂として用いられるポリカーボネート系樹脂の分子量は特に制限されないが、後述するゲルパーミエーションクロマトグラフィー（ＧＰＣ）において測定した分子量分布において、ピーク分子量が１０００〜５０００００の分子量領域にあるものが好ましく、さらに好ましくは２０００〜１０００００の分子量領域にあることが良い。ピーク分子量が分子量１０００よりも低いトナー融着等の耐久性に悪影響が出る場合があり、分子量５０００００よりも高いと耐久性はより一層向上するものの、溶融粘度が高くなりすぎ、定着性とのバランスがとりにくくなる。本発明において使用されるポリカーボネート系樹脂を製造するに際し、適当な分子量調節剤、粘弾性改善のための分岐剤、反応を促進するための触媒等を必要に応じて使用することができる。
【００５７】
本発明の画像形成方法用のトナーに使用される結着樹脂において、ポリカーボネート系樹脂と併用される他の樹脂としては、一般に用いられるスチレン−アクリル系樹脂、スチレン−ブタジエン系樹脂、ポリエステル系樹脂及びエポキシ系樹脂が挙げられ、特にスチレン−アクリル系樹脂、ポリエステル系樹脂及びエポキシ系樹脂が好適に使用される。これらの樹脂はあらゆる公知の方法により製造すればよく、例えばスチレン−アクリル系樹脂は、それらを形成するための単量体を重合することにより得ることができる。具体的には、スチレン、ｏ（ｍ−，ｐ−）−メチルスチレン、ｍ（ｐ−）−エチルスチレンの如きスチレン系単量体、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体、ブタジエン、イソプレン、シクロヘキセン、（メタ）アクリロニトリル、アクリルアミドの如きエン系単量体が好ましく用いられる。これらは単独、または一般的には出版物ポリマーハンドブック第２版ＩＩＩ−ｐ１３９〜１９２（Ｊｏｈｎ Ｗｉｌｅｙ ＆ Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を適宜混合して用いられる。理論ガラス転移温度が４０℃未満の場合にはトナーの保存安定性や耐久安定性の面から問題が生じやすく、一方７５℃を超える場合にはトナーの定着点の上昇をもたらす。特にフルカラー画像を形成するためのカラートナーの場合においては各色トナーの定着時の混色性が低下し色再現性に乏しく、さらにＯＨＰ画像の透明性が低下するため好ましくない。
【００５８】
本発明の画像形成方法に係わるトナーは、ＴＨＦ可溶分のＧＰＣによる分子量分布において、分子量１０００以下の成分中に含まれるポリカーボネート系樹脂の繰り返し単位を構造中に有する成分の含有量が、該トナーを基準として１５．０重量％以下である場合、耐久性がより向上する。
【００５９】
一般に、ポリカーボネート系樹脂中に含有される不純物の種類としては、該ポリカーボネート系樹脂の種類や製造方法によっても異なり、該ポリカーボネート系樹脂の原料、副原料、副生成物、これらの分解物、重合触媒、重合停止剤、重合溶媒及び酸化防止剤の如き様々な化合物がある。一例を挙げれば、塩素化された脂肪族および芳香族炭化水素（例えばジクロロメタン）、ホスゲン、フェノール、ｔ−ブチルフェノール、有機アミン、塩化ナトリウム、１分子中に２個以上の水酸基を有する芳香族化合物（例えば２，２−ビス（３−メチル−４−ヒドロキシフェニル）プロパンの如き該ポリカーボネート系樹脂の単量体として用いられた二価フェノール）、１分子中に２個以上の水酸基を有する脂肪族化合物（例えば１，４−ブタンジオールの如き該ポリカーボネート系樹脂の単量体として用いられたジオール）、ポリカーボネートオリゴマー、１分子中に２個以上の水酸基を有する化合物と重合停止剤とが炭酸を介してエステル結合した化合物（例えば二価フェノールとｐ−ターシャリーブチルフェノールとが炭酸を介してエステル結合した化合物）、１分子中に２個以上の水酸基を有する芳香族化合物のモノおよび／またはジホルメート類（例えばフェニレンビスクロロホルメート）、１分子中に２個以上の水酸基を有する脂肪族化合物のモノおよび／またはジホルメート類（例えばエチレンビスクロロホルメート）、ジアリールカーボネート（例えばジフェニルカーボネート）、ジアルキルカーボネート（例えばジメチルカーボネート）がある。
【００６０】
これらの不純物のうち、ジクロロメタンなどの低沸点の化合物や塩化ナトリウムなどの水溶性化合物は、該ポリカーボネート系樹脂の製造工程で比較的容易に除去することができるが、高沸点の不純物については通常ポリカーボネート系樹脂中に残留することが多い。これらの高沸点で低分子量の不純物のうち、、該ポリカーボネート系樹脂の製造時に用いる１分子中に２個以上の水酸基を有する単量体（例えば二価フェノール類）および該ポリカーボネート系樹脂の繰り返し単位を構造中に有する分子量１０００以下の成分（ポリカーボネートオリゴマーや水酸基を１分子中に２個以上有する化合物と１価フェノールなどの重合停止剤が炭酸を介してエステル結合した化合物）を多く含有するトナーを製造した場合、本発明における重要な技術ポイントである耐久性（現像剤担持体、感光体、中間転写体への融着）の低下のみならず、トナーの帯電量の低下（画像濃度低下やカブリ増加）、トナーの環境安定性の低下、フェノール系不純物の空気酸化による着色（画像の変色）、定着時の不純物臭気、不純物の結晶化によるＯＨＰ透過性の低下、粉砕法におけるトナー製造工程の一つである溶融混練工程での結着樹脂の予期せぬ架橋、重合法トナーの製造時のフェノール系不純物の重合禁止作用など、様々な重大な問題が起こり、長期の使用に不具合を生じる。
【００６１】
こういったトナーの様々な性能、耐久性に悪影響を与える化合物は、ポリカーボネート系樹脂の繰り返し単位を構造中に有する分子量１０００以下の成分だけでなく、ポリカーボネート系樹脂の単量体及びその誘導体につてもあてはまるが、該単量体及びその誘導体の含有量は、ポリカーボネート系樹脂の繰り返し単位を構造中に有する分子量１０００以下の成分の含有量と比例関係があり、このポリカーボネート系樹脂の繰り返し単位を構造中に有する分子量１０００以下の成分の含有量をトナーに対して１５．０重量％以下にしておけば、前記の諸問題を生じないことが本発明者らの種々の検討により判明した。さらに、トナーの性能、特性をさらに高めるためには、ポリカーボネート系樹脂の繰り返し単位を有する分子量１０００以下の成分の含有量を１０．０重量％以下にすることがより好ましく、特に好ましくは５．０重量％である。もちろんトナーの分析を種々行っても、ポリカーボネート系樹脂の繰り返し単位を構造中に有する分子量１０００以下の化合物が、全く検出されないほど再沈殿により精製されたポリカーボネート系樹脂を、結着樹脂として使用することが最も好ましい。
【００６２】
トナーがＧＰＣ測定による分子量分布において、分子量１０００以下の成分中に含まれるポリカーボネート系樹脂の繰り返し単位を構造中に有する成分を１５．０重量％より多く含有する場合には、トナーの耐久性が低下し、保存安定性の悪化や多数枚プリントアウトした際の画像濃度変化が大きくなる。また、環境変化に伴う転写効率の変動やカブリの増加を生じることがある。
【００６３】
本発明において、トナーのＴＨＦ可溶分のＧＰＣによる分子量分布において、分子量１０００以下の成分中に含まれるポリカーボネート系樹脂の繰り返し単位を構造中に有する成分の定性および定量分析は、様々な方法で実施することができる。例えば、トナーを核磁気共鳴スペクトル（¹ Ｈ−ＮＭＲ、¹³Ｃ−ＮＭＲ）、赤外吸収スペクトル（ＩＲ）、ラマンスペクトル、紫外吸収スペクトル（ＵＶ）、質量スペクトル（ＭＳ）等のスペクトル分析、元素分析、ＧＰＣ、ガスクロマトグラフィー（ＧＣ）、液体クロマトグラフィー（ＨＰＬＣ）、その他の化学分析により分析すればよい。トナー自体では分析が困難な場合には、テトラヒドロフラン、トルエンの如き結着樹脂を溶解する溶剤でトナーをソックスレー抽出し、濾液をエバポレーターで濃縮後、前記の分析を行えばよい。さらに、液体クロマトグラフィーやＧＰＣにより分子量１０００以下の成分を分取したサンプルや、単独の、あるいは混合した溶媒で抽出したサンプルについて上記分析を行うなど、様々な分析手段の採用が可能である。これらの分析手段は単独で、また必要に応じて組み合わせて用いることが可能である。さらに、トナー中の分子量１０００以下の成分をＧＰＣにより分取し、この分取した成分を例えばアルカリで完全に加水分解した後、¹ Ｈ−ＮＭＲ、¹³Ｃ−ＮＭＲおよびＩＲの如き分析手段で該ポリカーボネート系樹脂の製造時に用いた１分子中に２個以上の水酸基を有する単量体（例えば二価フェノール類）の定性および定量分析を行うという方法もある。もちろんこの際に定量される単量体の含有量は、ＧＰＣ分子量１０００以下のポリカーボネートオリゴマーや水酸基を１分子中に２個以上有する化合物と１価フェノールの如き重合停止剤とが炭酸を介してエステル結合した化合物の加水分解により生成した単量体と、もともと該ポリカーボネート系樹脂中に含有されていた（重合時の）残留単量体の総和であるが、この総和の含有量を（別途に重合停止剤の定性、定量を行った後に）ポリカーボネートオリゴマー、および単量体と重合停止剤とが炭酸を介してエステル結合した化合物の含有量に換算した値が、トナーに対して１５．０重量％以下であれば、結果としてポリカーボネート系樹脂の繰り返し単位を構造中に有するＧＰＣ分子量１０００以下の化合物の含有量も１５．０重量％を超えることはありえず、本発明によるトナーの分析方法の一つの手段として採用することができる。
【００６４】
トナーのＴＨＦ可溶分及び樹脂の分子量分布は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により測定される。具体的なＧＰＣの測定方法としては、樹脂等のサンプルをテトラヒドロフラン（ＴＨＦ）に室温で２４時間かけて溶解した溶液を、ポア径が０．２μｍの耐溶剤性メンブランフィルターで濾過してサンプル溶液とし、以下の条件で測定する。尚、サンプル調製は、ＴＨＦに可溶な成分の濃度が０．４〜０．６重量％になるようにＴＨＦの量を調整する。
装置：高速ＧＰＣ ＨＬＣ８１２０ ＧＰＣ（東ソー社製）
カラム：Ｓｈｏｄｅｘ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７の７連（昭和電工社製）
溶離液：テトラヒドロフラン
流速：１．０ｍｌ／ｍｉｎ
オーブン温度：４０．０℃
試料注入量：０．０１ｍｌ
【００６５】
また、試料の分子量の算出にあたっては、標準ポリスチレン樹脂（東ソー社製ＴＳＫ スタンダード ポリスチレン Ｆ−８５０、Ｆ−４５０、Ｆ−２８８、Ｆ−１２８、Ｆ−８０、Ｆ−４０、Ｆ−２０、Ｆ−１０、Ｆ−４、Ｆ−２、Ｆ−１、Ａ−５０００、Ａ−２５００、Ａ−１０００、Ａ−５００）により作成した分子量校正曲線を使用する。
【００６６】
本発明においては、ポリカーボネート系樹脂がトナー粒子の表面に含有しているトナーを用いることが、トナーの耐久性をより向上させることができることからより好ましい。
【００６７】
トナー粒子の表面にポリカーボネート系樹脂が存在することの確認は、あらゆる分析手段を用いて実施することができる。一例を挙げれば、まずＴＥＭによりトナーの断層面観察を行い、トナー表面部分にコントラストがついているか確認する。表面にポリカーボネート系樹脂が存在する場合には、その部分にコントラストがつく。具体的には、常温硬化性のエポキシ樹脂中にトナー粒子を充分分散させた後４０℃の雰囲気下で２日間硬化させ得られた硬化物に染色を施した後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出して透過電子顕微鏡を用いトナーの断層面を観察する。本発明においては、用いるワックス成分と外殻を構成する結着樹脂との若干の結晶化度の違いを利用して材料間のコントラストをつけるため四三酸化ルテニウム染色法を、必要により四三酸化オスミウムと併用して用いることが好ましい。
【００６８】
次いで、光音響分光法（ＰＡＳ＝Ｐｈｏｔｏａｃｏｕｓｔｉｃ Ｓｐｅｃｔｒｏｓｃｏｐｙ）を用い、可動鏡のスキャンスピードを変えることで、得られたトナー粒子表面の組成を赤外線吸収スペクトル（ＩＲ）／ＰＡＳにより分析する。前記のＴＥＭ観察でトナー表面に連続に、又は不連続にコントラストが観察され、かつ、ＩＲ／ＰＡＳによる分析でポリカーボネート系樹脂が確認されれば、トナー表面にポリカーボネート系樹脂が存在していると判断できる。
【００６９】
又、ＩＲ／ＰＡＳの他にもラマン分光法と上記ＰＡＳを組み合わせたトナー表面の組成分析、ＥＳＣＡ（Ｅｌｅｃｔｒｏｎ Ｓｐｅｃｔｒｏｓｃｏｐｙ ｆｏｒ Ｃｈｅｍｉｃａｌ Ａｎａｌｙｓｉｓ）によるトナー表面の元素分析、エネルギー分散型Ｘ線分光器や電子線エネルギー分析器を取り付けた電子顕微鏡によるトナー表面の元素分析など様々な分析手段がある。これらの分析手段は単独で、又必要に応じて組み合わせて用いられる。
【００７０】
後述する重合法により本発明のトナーを製造する場合には、得られたトナー粒子のＴＨＦ可溶分のＧＰＣによる分子量分布において、分子量５０００〜１０万の領域にメインピークを有し、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）の比（Ｍｗ／Ｍｎ）２〜３００を有することが好ましい。
【００７１】
本発明に係るトナーは、画像解析装置で測定した形状係数ＳＦ−１の値が１００〜１６０であり、形状係数ＳＦ−２の値が１００〜１４０であることが好ましく、形状係数ＳＦ−１の値が１００〜１４０であり、形状係数ＳＦ−２の値が１００〜１２０であれば更に好ましい。更に前記の条件を満たし、かつ、（ＳＦ−２）／（ＳＦ−１）の値が１．０以下であれば、特に好ましい。
【００７２】
本発明において、形状係数を示すＳＦ−１とは、例えば日立製作所製ＦＥ−ＳＥＭ（Ｓ−８００）を用いた倍率５００倍に拡大したトナー像を１００個無作為にサンプリングし、その画像情報はインターフェイスを介して例えばニコレ社製画像解析装置（Ｌｕｚｅｘ ＩＩＩ）を導入し解析を行い、下式より算出し得られた値を形状係数ＳＦ−１と定義する。
【００７３】
【外４】

〔式中、ＭＸＬＮＧはトナーの絶対最大長を示し、ＡＲＥＡはトナーの投影面積を示す。〕
【００７４】
更に、形状係数ＳＦ−２は、下記式より算出して得られた値をいう。
【００７５】
【外５】

〔式中、ＰＥＲＩは、トナーの周長を示し、ＡＲＥＡはトナーの投影面積を示す。〕
【００７６】
形状係数ＳＦ−１はトナーの丸さの度合いを示し、形状係数ＳＦ−２はトナー粒子の凹凸の度合いを示している。これらの形状係数を制御することにより、多数枚の画出しにおける感光体上・トナー担持体上・中間転写体上のトナー融着を改善でき、本発明の画像形成方法における耐久性を更に向上させることができる。
【００７７】
１６０＜ＳＦ−１の場合、球形から離れて不定形に近づき、現像器内でトナーが破砕され易く、粒度分布が変動したり、帯電量分布がブロードになりやすく、感光体上の非画像部へのトナーの現像、所謂カブリが生じやすい。又、トナーの接触面積が大きくなるため、感光体上・トナー担持体上・中間転写体上に付着しやすくなり、トナー融着の一因となるため好ましくない。
【００７８】
１４０＜ＳＦ−２の場合、転写材へのトナーの転写効率の低下を招き、転写残トナーが増加するため、本発明の特徴の一つである中間転写体を用いる構成においてはクリーニング部材を強く押し当てる必要が生じ、トナー融着が促進されることになるため、好ましくない。
【００７９】
（ＳＦ−２）／（ＳＦ−１）の値が１．０を超える場合、トナー粒子の表面が滑らかではなく、多数の凹凸をトナー粒子が有しており、感光体から中間転写体への転写時および中間転写体から転写材への転写時に転写効率が低下する傾向にあり、やはりトナー融着が促進される構成にならざるをえなく、好ましくない。
【００８０】
特に上記の如き傾向は、特に、中間転写体を用いた複数のトナー像を現像／転写せしめるフルカラー画像形成装置を用いた場合に顕在化する。すなわち、フルカラー画像の生成においては中間転写体上に４色分のトナー像が形成された後、転写材上へ一括して転写されるため、転写残トナー量がどうしても多くなるからである。
【００８１】
更にその場合、転写工程が実質２回行われるため、転写効率の低下率は著しくトナーの利用効率の低下を招き問題となる。デジタルフルカラー複写機やプリンターにおいては、色画像原稿を予めＢ（ブルー）フィルター、Ｇ（グリーン）フィルター、Ｒ（レッド）フィルターを用い色分解した後、感光体上に２０〜７０μｍのドット潜像を形成し、Ｙ（イエロー）トナー、Ｍ（マゼンタ）トナー、Ｃ（シアン）トナー、Ｂ（ブラック）トナーの各色トナーを用いて原色混合作用を利用し原稿に忠実な多色カラー画像を再現する必要がある。この際、感光体上又は中間転写体上には、Ｙトナー、Ｍトナー、Ｃトナー、Ｂトナーが原稿やＣＲＴの色情報に対応して多量にトナーが乗るため本発明に使用される各カラートナーは、極めて高い転写性が要求され、それを実現させるためにはトナーの形状係数ＳＦ−１およびＳＦ−２が上記条件を満足しているトナー粒子が好ましい。
【００８２】
本発明の画像形成方法には、重量平均粒径が、２μｍ〜１０μｍ、好ましくは２〜９μｍ、より好ましくは４μｍ〜８μｍを有するトナーを用いる場合、非常に高画質な画像を長期間安定に得ることができる。
【００８３】
一般に、トナーの粒径が細かくなると、現像時の解像度が向上することが知られているものの、トナー全体の表面積が増えることに加え、トナー粉体としての流動性および撹拌性が低下し、個々の粒子を均一に帯電させることが困難となることに加え、感光体や中間転写体などへの付着力が増大し、トナー融着の要因となる。
【００８４】
しかしながら、トナーのＳＦ−１およびＳＦ−２を本発明に記した如く規制することにより、粒径の小さいトナーであっても個々の粒子を均一に帯電させることが可能となることに加え、分子量１０００以下の成分の含有量が少ないポリカーボネート系樹脂を含有させることによりトナー粒子間の凝集が抑制され、高精細な画像を長期に渡って得ることができる。
【００８５】
トナーの粒度分布は種々の方法によって測定できる。本発明においてはコールターカウンターを用いて行った。
【００８６】
例えば測定装置としてはコールターカウンターＴＡ−ＩＩ型（コールター社製）を用い、個数分布および体積分布を出力するインターフェイス（日科機製）およびパーソナルコンピューターを接続し、電解液は１級塩化ナトリウムを用いて約１％ＮａＣｌ水溶液を調製する。例えばＩＳＯＴＯＮ 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１０〜１５０ｍｌ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ホン酸塩）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機で約１〜３分間分散処理を行い、前記コールターカウンターＴＡ−ＩＩ型により、アパチャーとして例えば１００μｍアパチャーを用い、本発明に係るトナー粒径を求める。
【００８７】
本発明の画像形成方法に係わるトナーに用いられるワックス成分としては、例えばパラフィンワックスおよびその誘導体、マイクロクリスタリンワックスおよびその誘導体、フィツシャートロプシュワックスおよびその誘導体、ポリオレフィンワックスおよびその誘導体、カルナバワックスおよびその誘導体、高級脂肪酸およびその金属塩、高級脂肪族アルコール、高級脂肪族エステル、脂肪族アミドワックス、ケトン、硬化ヒマシ油およびその誘導体、植物系ワックス、動物性ワックス、鉱物系ワックス、ペトラクタムが挙げられる。誘導体は、酸化物や、ビニル系モノマーとのブロック共重合物、グラフト変性物を含む。
【００８８】
これらのワックス成分の内でも、示差走査熱量計により測定されるＤＳＣ曲線において、昇温時に４０〜１３０℃の領域に最大吸熱ピークを有するものが好ましく、好ましくは４０〜９０℃の領域に有するものがより好ましい。上記温度領域に最大吸熱ピークを有することにより、低温定着に大きく貢献しつつ、離型性をも効果的に発現する。該最大吸熱ピークが４０℃未満であるとワックス成分の自己凝集力が弱くなり、結果として耐高温オフセット性が悪化する。一方、該最大吸熱ピークが１３０℃を超えると定着温度が高くなり低温オフセットが発生しやすくなるとともに、定着画像表面を適度に平滑化せしめることが困難となるため、特にカラートナーに用いた場合には混色性低下の点から好ましくない。更に、水系媒体中で造粒／重合を行い重合方法により直接トナーを得る場合、該最大吸熱ピーク温度が高いと主に造粒中にワックス成分が析出する等の問題を生じ好ましくない。
【００８９】
ワックス成分の最大吸熱ピーク温度の測定は、「ＡＳＴＭ Ｄ ３４１８−８」に準じて行う。測定には、例えばパーキンエルマー社製ＤＳＣ−７を用いる。装置検出部の温度補正はインジウムと亜鉛の融点を用い、熱量の補正についてはインジウムの融解熱を用いる。測定サンプルにはアルミニウム製のパンを用い、対照用に空パンをセットし、昇温速度１０℃／ｍｉｎで温度１０℃〜１８０℃まで昇温し測定を行う。
【００９０】
本発明においては、これらのワックス成分の添加量は特に含有量としては、トナー全体に対して０．１〜５０重量％、好ましくは０．５〜３０重量％の範囲が好ましい。含有量が０．１重量％未満ではオフセット抑制効果に乏しく、５０重量％を超えてしまうと長期間の保存性が悪化すると共に、他のトナー材料の分散性が悪くなり、画像特性の低下につながる。
【００９１】
本発明の画像形成方法に係わるトナーに用いられる着色剤は、以下に示すイエロー着色剤、マゼンダ着色剤およびシアン着色剤が挙げられ、黒色着色剤としてカーボンブラック、磁性体、チタンブラックあるいはこれらの混合物、又は以下に示すイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用される。
【００９２】
イエロー着色剤としては、縮合アゾ化合物、イソインドリノン化合物、アンスラキノン化合物、アゾ金属錯体、メチン化合物、アリルアミド化合物に代表される化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８、１８０が好適に用いられる。
【００９３】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物、アンスラキノン、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物、ペリレン化合物などが用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８：２、４８：３、４８：４、５７：１、８１：１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４が特に好ましい。
【００９４】
シアン着色剤としては、銅フタロシアニン化合物およびその誘導体、アンスラキノン化合物、塩基染料レーキ化合物などが利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６が特に好適に利用できる。
【００９５】
これらの着色剤は、単独又は混合しさらには固溶体の状態で用いることができる。着色剤は、色相、彩度、明度、耐候性、ＯＨＰ透明性、分散性の点から選択される。該着色剤の添加量は、トナー中の粘着樹脂１００重量部に対し１〜２０重量部含有されていることが好ましい。１重量部未満では十分な着色力が得られず、２０重量部を超えるとＯＨＰ画像の透明性が低下する。
【００９６】
更に本発明の画像形成方法に係わるトナーは、黒色着色剤として磁性材料を使用し、磁性トナーとしても使用し得る。この際使用することのできる磁性材料としては、マグネタイト、ヘマタイト、フェライトなどの酸化鉄、鉄、コバルト、ニッケルのような金属あるいはこれらの金属のアルミニウム、コバルト、銅、鉛、マグネシウム、スズ、亜鉛、アンチモン、ベリリウム、ビスマス、カドニウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムのような金属の合金およびその混合物があげられる。
【００９７】
これらの磁性体は平均粒径が２μｍ以下、好ましくは０．１〜０．５μｍ程度のものである。トナー粒子中に含有させる磁性体の量としては樹脂１００重量部に対し２０〜２００重量部、特に好ましくは４０〜１５０重量部である。又、１０Ｋエルステッド印加での磁気特性が保磁力（Ｈｃ）２０〜３００エルステッド、飽和磁化（σｓ）５０〜２００ｅｍｕ／ｇ、残留磁化（σｒ）２〜２０ｅｍｕ／ｇの磁性体が好ましい。
【００９８】
本発明の画像形成方法に係わるトナーに用いられる荷電制御剤としては、公知のものが利用でき、特に帯電スピードが速く、かつ、一定の帯電量を安定して維持できる荷電制御剤が好ましい。更に、トナー粒子を直接重合法を用いて製造する場合には、重合阻害性が低く、水系分散媒体への可溶化物が実質的にない荷電制御剤が特に好ましい。具体的な化合物としては、ネガ系荷電制御剤としてサリチル酸、ナフトエ酸、ダイカルボン酸の如き芳香族カルボン酸の金属化合物、アゾ染料あるいはアゾ顔料の金属塩又は金属錯体、スルホン酸又はカルボン酸基を側鎖に持つ高分子型化合物、ホウ素化合物、尿素化合物、ケイ素化合物、カリックスアレーン等が挙げられる。ポジ系荷電制御剤として四級アンモニウム塩、該四級アンモニウム塩を側鎖に有する高分子型化合物、グアニジン化合物、イミダゾール化合物等が挙げられる。該荷電制御剤は樹脂１００重量部に対し０．５〜１０重量部使用することが好ましい。しかしながら、本発明において荷電制御剤の添加は必須ではなく、現像剤規制（ブレード）部材やトナー担持体との摩擦帯電を積極的に利用することでトナー粒子中に必ずしも荷電制御剤を含む必要はない。
【００９９】
本発明の画像形成方法に係わるトナーの製造方法としては様々な方法が挙げられるが、例えば粉砕法により製造する場合には、ポリカーボネート系樹脂を含む結着樹脂、ワックス成分、着色剤および／又は磁性体、荷電制御剤又はその他の添加剤等をヘンシェルミキサー、ボールミルの如き混合機により充分混合し、加圧ニーダーやエクストルーダーの如き熱混練機を用いて溶融混練し、冷却固化後に固形物を機械的又はジェット気流下でターゲットに衝突させ、所望のトナー粒径に微粉砕化する。次いで、分級工程を経て粒度分布をシャープにする。微粉砕化後あるいは分級工程後に、必要に応じてトナー粒子の平滑化および球形化処理を行っても良い。更に、分級粉を微粒子シリカ微粒子の如き流動化剤とヘンシェルミキサーの如き混合機により充分混合することで本発明のトナーを得ることができる。上記粉砕法による製造方法を採用する場合に、ポリカーボネート系樹脂と他の樹脂をキシレンの如き有機溶剤に（必要により加熱）溶解して均一に混合し、その後溶剤を除去した結着樹脂混合物を原料として用いれば、ガラス転移温度の高いポリカーボネート系樹脂であってもトナー中への分散が良好となり、特に好ましい製造方法となる。
【０１００】
更に、その他のトナーの製造方法として、分級粉に超微粉化したポリカーボネート系樹脂を加えて充分混合し、トナー表面にポリカーボネート系樹脂を熱的あるいは機械的に固着させる方法もあり、この場合、分級粉中の結着樹脂にポリカーボネート系樹脂が含まれていてもよいし、全く含まれていなくてもよい。又、固着させた後にトナー粒子の平滑化および球形化処理を行ってもよい。
【０１０１】
更に、重合法により本発明のトナーを製造する場合には、重合系にポリカーボネート系樹脂を添加し、特公昭３６−１０２３１号公報、特開昭５９−５３８５６号公報、特開昭５９−６１８４２号公報に述べられているような懸濁重合方法を用いて直接トナーを製造する方法、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを製造する分散重合方法又は水溶性重合開始剤存在下で直接重合しトナーを製造するソープフリー重合法に代表される乳化重合方法などにより本発明のトナーを得ることができる。又、重合法によりポリカーボネート系樹脂を含有しない重合体粒子を製造し、その後、重合体粒子の表面に微粒子状のポリカーボネート系樹脂を付着させ、必要に応じて粒子の平滑化および球形化処理を行う方法も採用することができる。又、その他の方法として、特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用いポリカーボネート系樹脂を含有するトナー原料混合物を空気中に霧化し球形トナーを得る方法などが例示される。
【０１０２】
前記したトナーの製造方法のうち、溶融スプレー法はルーゼックスで測定したトナーの球状係数であるＳＦ−１値を１００〜１６０に納めることができても、得られたトナーの粒度分布が広くなりやすい。他方、分散重合法は、得られるトナーは極めてシャープな粒度分布を示すが、使用する材料の選択が狭いことや有機溶剤の利用が廃溶剤の処理や溶剤の引火性に関する観点から製造装置が複雑で煩雑化しやすい。又、乳化重合方法は、トナーの粒度分布が比較的揃うという利点はあるが、一般に生成する粒子の粒度は非常に細かく、トナーとしてそのまま使用することは困難である。更に、使用した水溶性重合開始剤の末端や乳化剤がトナー粒子表面に存在し、環境特性を悪化させることがある。
【０１０３】
一方、トナー粒子の平滑化および球形化処理による製造方法、および重合法による製造方法は、ＳＦ−１の値を１００〜１６０、ＳＦ−２の値を１００〜１４０の範囲に収めることが容易であり、好ましい製造方法といえる。又、重合法により本発明のトナーを製造する方法は、ＳＦ−１の値を１００〜１４０、ＳＦ−２の値を１００〜１２０、（ＳＦ−２）／（ＳＦ−１）の値を１．０以下に制御することが非常に容易であり、又、たとえ溶融温度の高いポリカーボネート系樹脂であっても、使用する単量体組成物中に溶解すれば使用できるので、使用できるポリカーボネート系樹脂の種類が多く、特に好ましい製造方法である。
【０１０４】
本発明のトナーに含有されるポリカーボネート系樹脂は、トナー中に如何なる形状、状態で含有されていてもよく、他の結着樹脂と相溶した状態であっても、相分離した状態であってもよい。例えば、前記した粉砕法でポリカーボネート系樹脂と他の結着樹脂を溶融混練する場合、この溶融混練工程で必ずしもポリカーボネート系樹脂も溶融されている必要はなく、溶融された他の結着樹脂の中に分散した状態であってもよい。このような場合には、トナー中のポリカーボネート系樹脂は併用される他の結着樹脂中に分散された状態となる。ポリカーボネート系樹脂と他の結着樹脂をキシレンの如き有機溶剤を用いてあらかじめ均一に溶解混合した場合には、ポリカーボネート系樹脂が他の樹脂中に微分散、または場合により相溶化されるため問題はないが、この様な均一化操作を実施せずにポリカーボネート系樹脂の粉末と他の結着樹脂を混練し、かつ、該ポリカーボネート系樹脂の溶融温度未満で混練を行う場合には、ポリカーボネート系樹脂粉末がそのままの粒径でトナー中に分散されることとなるため、例えば１μｍ以下、好ましくは０．５μｍ以下に微粉砕したポリカーボネート系樹脂を用いるのがよい。
【０１０５】
更には、重合法とトナー粒子の平滑化および球形化処理を組み合わせた製造方法、重合法により直接ポリカーボネート系樹脂が連続に、又は、不連続に表面に存在しているトナーを製造する方法がより好ましい。この方法では、ＳＦ−１の値を１００〜１４０、ＳＦ−２の値を１００〜１２０、（ＳＦ−２）／（ＳＦ−１）の値を１．０以下に制御することが容易であり、更に、透過型電子顕微鏡（ＴＥＭ）を用いた前記トナーの断層面観察において、ポリカーボネート系樹脂が連続に、又は、不連続に表面に存在しており、その内部にビニル系単量体から得られる結着樹脂とワックス成分が存在し、ワックス成分が結着樹脂中に実質的に球状および／又は紡錘形の島状に分散されているため、環境による帯電特性の変動が少なく、転写性、現像性、低温定着性、耐ブロッキング性などに優れたトナーを得ることができ、非常に好ましい製造方法である。
【０１０６】
トナーの製造方法として重合法を利用する場合、トナー粒子の粒度分布制御や粒径の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件（例えばローターの周速、パス回数、撹拌羽根形状等の撹拌条件や容器形状）又は、水溶液中での固形分濃度等を制御することにより所定のトナー粒子を得ることができる。
【０１０７】
直接重合法によりトナーを製造する際、用いられる重合開始剤として例えば、２，２’−アゾビス（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系又はジアゾ系重合開始剤；ベンゾイルパーオキサイド、メチルエチルケトンパーオキサイド、ジイソプロピルパーオキシカーボネート、クメンヒドロパーオキサイド、２，４−ジクロロベンゾイルパーオキサイド、ラウロイルパーオキサイドの如き過酸化物系重合開始剤が用いられる。該重合開始剤の使用量は、目的とする重合度により変化するが一般的には重合性単量体に対し０．５〜２０重量％が用いられる。重合開始剤の種類は、重合法により若干異なるが、十時間半減期温度を参考に、単独又は混合して使用される。又、重合度を制御するために公知の架橋剤、連鎖移動剤、重合禁止剤などを更に添加して用いても良い。
【０１０８】
トナーの製造法として分散安定剤を用いた懸濁重合法を利用する場合、用いる分散安定剤としては、無機化合物としてリン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカおよびアルミナが挙げられる。有機化合物としては、ポリビニルアルコール、ゼラチン、ヒドロキシエチルセルロース、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースおよびそのナトリウム塩およびポリアクリル酸およびその塩、デンプンが挙げられる。これらの分散安定剤は、重合性単量体１００重量部に対して０．２〜２０重量部を使用することが好ましい。
【０１０９】
分散安定剤として、無機化合物を用いる場合、市販のものをそのまま用いても良いが、細かい粒子を得るために、分散媒体中にて該無機化合物の微粒子を生成しても良い。例えば、リン酸三カルシウムの場合、拘束撹拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合すると良い。
【０１１０】
これら分散安定剤の微細な分散のために、０．００１〜０．１重量部の界面活性剤を併用しても良い。これは上記分散安定剤の作用を促進するためのものであり、例えば、ドデシルベンゼン硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等が挙げられる。
【０１１１】
本発明の画像形成方法に係わるトナーの製造方法として直接重合法を用いる場合においては、以下の如き製造方法が可能である。
【０１１２】
重合性単量体中に、ワックス成分、着色剤、荷電制御剤、重合開始剤その他の添加剤を加え、ホモジナイザー、超音波分散機等によって均一に溶解または分散した単量体組成物を、分散安定剤を含有する水相中に通常の撹拌機またはホモミキサー、ホモジナイザー等により分散させる。好ましくは単量体組成物の液滴が所望のトナー粒子のサイズを有するように撹拌速度、撹拌時間を調整し造粒する。その後は分散安定剤の作用により、粒子状態が維持され、かつ、粒子の沈降が防止される程度の撹拌を行えばよい。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行うのがよい。重合反応後半に昇温をしてもよく、さらに、本発明における画像形成方法では耐久性の向上の目的で、未反応の重合性単量体、副生成物等を除去するための反応後半、または、反応終了後に一部水系媒体を反応系から留去してもよい。反応終了後、生成したトナー粒子を洗浄、濾過により回収し、乾燥する。懸濁重合法においては、通常単量体組成物１００重量部に対して水３００〜３０００重量部を分散媒体として使用するのが好ましい。
【０１１３】
本発明の画像形成方法に係わるトナーは、結着樹脂中にポリカーボネート系樹脂を含有することが必須であり、先述したように、結着樹脂の０．１〜５０重量％がポリカーボネート系樹脂であることが好ましいが、該ポリカーボネート系樹脂の定性および定量分析は様々な方法で実施することができる。例えば、トナーを該磁気共鳴スペクトル（ ¹Ｈ−ＮＭＲ、¹³Ｃ−ＮＭＲ）、赤外吸収スペクトル（ＩＲ）、ラマンスペクトル、紫外吸収スペクトル（ＵＶ）、質量スペクトル（ＭＳ）の如きスペクトル分析、元素分析、その他の化学分析など様々な方法により分析すればよい。また、トナー自体では分析が困難な場合には、テトラヒドロフラン、トルエン等の結着樹脂を溶解する溶剤でトナーをソックスレー抽出し、濾液をエバポレーターで濃縮後、前記の分析を行えばよい。さらに、ＧＰＣにより分取したサンプルや単独の、あるいは混合した溶媒で分別抽出したサンプルについて上記分析を行うなど、様々な分析手段の採用が可能である。これらの分析手段は単独で、また必要に応じて組み合わせて用いることが可能である。
【０１１４】
本発明の現像剤は、さらに流動性向上剤を添加して用いても良い。流動性向上剤としては、トナー粒子に添加することにより添加後の流動性が向上しうるものであれば特に限定されるものではない。例えば、シリカ微粉体、酸化チタン微粉体、アルミナ微粉体、それらの表面を疎水化処理したもの等を単体あるいは２種以上を併用して用いることができる。
【０１１５】
本発明の画像形成方法においては、種々の帯電方法が用いられる。もちろん、帯電部材を感光体に当接させる接触帯電法も好適に使用される。その場合、一般のトナーを使った場合、クリーニングの後の残トナーが後工程である直接帯電部材に付着すると、帯電不良を引き起こし、画像上に帯電ムラが発生する。従って、帯電手段が感光体に接することのないコロナ放電等に比べて、残トナーの量は、より少なく、付着し難くする必要がある。従って、直接帯電法においては、ＳＦ−１、ＳＦ−２、（ＳＦ−２）／（ＳＦ−１）を厳密に規定したトナーを使う必要がある。
【０１１６】
本発明の画像形成方法における現像工程の条件としては、少なくともトナー担持体に担持されているトナー層と感光体表面が接触しているものであり、好ましくはトナー担持体表面からトナー層を取り除いた状態でトナー担持体表面が感光体表面が接触していることが良く、より好ましくは反転現像方法を用いるということが良い。さらにクリーニングブレードの如きクリーニング手段を別途設けず、現像装置自体が感光体上の転写残トナーの回収を行うクリーナレスプロセスを併用することにより、装置の大幅な小型化が可能となる。このとき、現像時あるいは現像前後の空白時には、直流あるいは交流成分のバイアスを印加し、現像を行うと共に、感光体上の転写残トナーを回収出来るような電位に制御される。このとき直流成分は、明部電位と暗部電位の間に位置する。
【０１１７】
トナー担持体としては、弾性ローラを用い、弾性ローラ表面にトナーをコーティングしこれを感光体表面と接触させる方法も用いられる。この場合、トナーを介して感光体と感光体表面に対向する弾性ローラ間に働く電界によって、現像工程において、クリーナプロセスでは転写残トナーのクリーニングも行われるので、弾性ローラ表面あるいは、表面近傍が電位をもち、感光体表面とトナー担持表面の狭い間隙で電界を有する必要性がある。このため、弾性ローラの弾性ゴムが中抵抗領域に抵抗制御されて感光体表面との導通を防ぎつつ電界を保つか、または導電性ローラの表面層に薄層の絶縁層を設ける方法も利用できる。さらには、導電性ローラ上に感光体表面に対向する側を絶縁性物質により被覆した導電性樹脂スリーブあるいは、絶縁性スリーブで感光体に対向しない側に導電層を設けた構成も可能である。また、トナー担持体として剛体ローラを用い、感光体をベルトのごときフレキシブルなものとした構成も可能である。トナー担持体としての現像ローラの抵抗としては１０² 〜１０⁹ Ω・ｃｍの範囲が好ましい。
【０１１８】
トナー担持体の表面形状としては、その表面粗度Ｒａ（μｍ）を０．２〜３．０となるように設定すると、高画質及び高耐久性を両立できる。該表面粗度Ｒａはトナー搬送能力及びトナー帯電能力と相関する。該トナー担持体の表面粗度Ｒａが３．０を超えると、該トナー担持体上のトナー層の薄層化が困難となるばかりか、トナーの帯電性が改善されないので画質の向上は望めない。３．０以下にすることでトナー担持体表面のトナーの搬送能力を制御し、該トナー担持体上のトナー層を薄層化すると共に、該トナー担持体とトナーの接触回数が多くなるため、該トナーの帯電性も改善されるので相乗的に画質が向上する。一方、表面粗度Ｒａが０．２よりも小さくなると、トナーコート量の制御が難しくなる。
【０１１９】
本発明において、トナー担持体の表面粗度Ｒａは、ＪＩＳ表面粗さ「ＪＩＳＢ０６０１」に基づき、表面粗さ測定器（サーフコーダＳＥ−３０Ｈ、株式会社小坂研究所社製）を用いて測定される中心線平均粗さに相当する。具体的には、粗さ曲線からその中心線の方向に測定長さａとして２．５ｍｍの部分を抜き取り、この抜き取り部分の中心線をＸ軸、縦倍率の方向をＹ軸、粗さ曲線をｙ＝ｆ（ｘ）で表したとき、次式によって求められる値をミクロメートル（μｍ）で表したものを言う。
【０１２０】
【外６】

【０１２１】
本発明の画像形成方法においては、トナー担持体は感光体の周速同方向に回転していてもよいし、逆方向に回転していてもよい。その回転が同方向である場合、トナー担持体の周速を感光体の周速に対し１．０５〜３．０倍となるように設定することが好ましい。
【０１２２】
トナー担持体の周速が、感光体の周速に対し１．０５倍未満であると、トナー層の受ける撹拌効果が不十分となり、良好な画像品質が望めない。また、ベタ黒画像等、広い面積にわたって多くのトナー量を必要とする画像を現像する場合、静電潜像へのトナー供給量が不足し画像濃度が薄くなる。周速比が高まれば高まるほど、現像部位に供給されるトナーの量は多く、潜像に対しトナーの脱着頻度が多くなり、不要な部分は掻き落とされ必要な部分には付与されるという繰り返しにより、潜像に忠実な画像が得られる。現像兼クリーニングという観点では、感光体上に密着した転写残のトナーが存在する場合、感光体表面とトナーの付着部分を周速差により物理的に引き剥がし電界により回収すると言う効果も期待できることから、周速比は高いほど転写残余のトナーの回収には都合がよい。但し、逆に周速比が３．０を超える場合には、上記の如きトナーの過剰な帯電によって引き起こされる種々の問題の他に、機械的ストレスによるトナーの劣化やトナー担持体へのトナー固着が発生、促進され、好ましくない。
【０１２３】
感光体としては、ａ−Ｓｅ、Ｃｄｓ、ＺｎＯ₂ 、ＯＰＣ、ａ−Ｓｉの様な光導電絶縁物質層を持つ感光ドラムもしくは感光ベルトが好適に使用される。
【０１２４】
ＯＰＣ感光体における有機系感光層の結着樹脂は、ポリカーボネート樹脂、ポリエステル樹脂、アクリル系樹脂が特に、転写性、クリーニング性がよく、クリーニング不良、感光体へのトナーの融着、外添剤のフィルミングが起こりにくく、好ましい。
【０１２５】
次に本発明の画像形成方法を添付図面を参照しながら以下に説明する。
【０１２６】
まず、クリーナレスプロセスを用いた場合の、単色での画像形成方法について図１を用いて説明する。
【０１２７】
図１において、１００は現像装置、１０９は感光体、１０５は紙の如き記録材、１０６は転写部材、１０７は定着用加圧ローラ、１０８は定着用加熱ローラ、１１０は感光体１０９に接触して直接帯電を行う一次帯電部材を示す。
【０１２８】
一次帯電部材１１０には、感光体１０９表面を一様に帯電するようにバイアス電源１１５が接続されている。
【０１２９】
現像装置１００はトナー１０４を収容しており、感光体１０９と接触して矢印方向に回転するトナー担持体１０２を具備する。さらに、トナー量規制及び帯電付与のための現像ブレード１０１、トナー１０４をトナー担持体１０２に付着させかつトナー担持体１０２との摩擦でトナーへの帯電付与を行うため矢印方向に回転する塗布ローラ１０３も備えている。トナー担持体１０２には現像バイアス電源１１７が接続されている。塗布ローラ１０３にもバイアス電源１１８が接続されており、負帯電性トナーを使用する場合は現像バイアスよりも負側に、正帯電性トナーを使用する場合は現像バイアスよりも正側に電圧が設定される。
【０１３０】
転写部材１０６には感光体１０９と反対極性の転写バイアス電源１１６が接続されている。ここで、感光体１０９とトナー担持体１０２の接触部分における回転方向の長さ、いわゆる現像ニップ幅０．２ｍｍ以上８．０ｍｍ以下が好ましい。０．２ｍｍ未満では現像量が不足して満足な画像濃度が得られず、転写残トナーの回収も不十分となる。８．０ｍｍを超えてしまうと、トナーの供給量が過剰となり、カブリが発生し易くなり、さらに、感光体の摩耗にも悪影響を及ぼす。
【０１３１】
トナー担持体としては、表面に弾性層を有する、いわゆる弾性ローラが好ましく用いられる。使用される弾性層の材料の硬度としては、２０〜６５度（ＪＩＳＡ）のものが好適に使用される。また、トナー担持体の抵抗としては、体積抵抗値で１０² 〜１０⁹ Ωｃｍ程度の範囲が好ましい。１０² Ωｃｍよりも低い場合、例えば感光体１０９の表面にピンホール等がある場合、過電流が流れる恐れがある。反対に１０⁹ Ωｃｍよりも高い場合は、摩擦帯電によるトナーのチャージアップが起こりやすく、画像濃度の低下を招きやすい。
【０１３２】
トナー担持体上のトナーコート量は、０．１ｍｇ／ｃｍ² 以上１．５ｍｇ／ｃｍ² 以下が好ましい。０．１ｍｇ／ｃｍ² よりも少ないと十分な画像濃度が得にくく、１．５ｍｇ／ｃｍ² よりも多くなると個々のトナー粒子全てを均一に摩擦帯電することが難しくなり、カブリ抑制の悪化の要因となる。さらに、０．２ｍｇ／ｃｍ² 以上０．９ｍｇ／ｃｍ² 以下がより好ましい。
【０１３３】
トナーコート量は現像ブレード１０１により制御されるが、この現像ブレード１０１はトナー層を介してトナー担持体１０２に接触している。この時の接触圧は、５ｇ／ｃｍ以上５０ｇ／ｃｍ以下が好ましい範囲である。接触圧が５ｇ／ｃｍよりも小さいとトナーコート量の制御に加え均一な摩擦帯電も難しくなり、カブリの発生の原因となる。接触圧が５０ｇ／ｃｍよりも大きくなるとトナー粒子が過剰な負荷を受けるため、粒子の変形や現像ブレードあるいはトナー担持体へのトナーの融着等が発生しやすくなる。
【０１３４】
トナーコート量の規制部材としては、トナーを圧接塗布するための弾性ブレード以外にも、金属ブレードあるいはローラ等を用いても良い。
【０１３５】
弾性の規制部材には所望の極性にトナーを帯電させるのに適した摩擦帯電系列の材質を選択することが好ましく、シリコーンゴム、ウレタンゴム、ＮＢＲの如きゴム弾性体、ポリエチレンテレフタレートの如き合成樹脂弾性体、ステンレス、銅、リン青銅の如き金属弾性体、それらの複合体が使用できる。
【０１３６】
また、弾性の規制部材とトナー担持体に耐久性が要求される場合には、金属弾性体に樹脂やゴムをスリーブ当接部に当たるように貼り合わせたり、コーティング塗布したものが好ましい。
【０１３７】
更に、弾性の規制部材中に有機物や無機物を添加してもよく、溶融混合させても良いし、分散させても良い。例えば、金属酸化物、金属粉、セラミックス、炭素同素体、ウィスカー、無機繊維、染料、顔料、又は界面活性剤を添加することにより、トナーの帯電性をコントロールできる。特に、弾性体がゴムや樹脂の成型体の場合には、シリカ、アルミナ、チタニア、酸化錫、酸化ジルコニア、酸化亜鉛の如き金属酸化物微粉末、カーボンブラク、一般にトナーに用いられる荷電制御材等を含有させることも好ましい。
【０１３８】
さらに、規制部材に直流電場及び／または交流電場を印加することによっても、トナーへのほぐし作用のため、均一薄層塗布性、均一帯電性がより向上し、充分な画像濃度の達成及び良質の画像を得ることができる。
【０１３９】
図１において、一次帯電部材１１０は矢印方向に回転する感光体１０９を一様に帯電する。ここで用いている一次帯電部材は、中心の芯金１１０ｂとその外周を形成した導電性弾性層１１０ａとを基本構成とする帯電ローラである。帯電ローラ１１０は、静電潜像担持体一面に押圧力を持って当接され、静電潜像担持体１の回転に伴い従動回転する。
【０１４０】
帯電ローラを用いたときの好ましいプロセス条件としては、ローラの当接圧が５〜５００ｇ／ｃｍであり、印加電圧としては直流電圧単独の帯電バイアスあるいは直流電圧に交流電圧を重畳した帯電バイアスが用いられる。特に限定されないが、本発明においては直流電圧のみの帯電バイアスが好適に用いられ、この場合の電圧値としては±０．２〜±５ｋＶの範囲で使用される。
【０１４１】
この他の帯電手段としては、帯電ブレードを用いる方法や、導電性ブラシを用いる方法がある。これらの接触帯電手段は、非接触のコロナ帯電に比べて、高電圧が不必要になったり、オゾンの発生が低減するといった効果がある。接触帯電手段としての帯電ローラおよび帯電ブレードの材質としては、導電性ゴムが好ましく、その表面に離型性被膜を設けても良い。離型性被膜としては、ナイロン系樹脂、ＰＶＤＦ（ポリフッ化ビニリデン）又はＰＶＤＣ（ポリ塩化ビニリデン）が適用可能である。
【０１４２】
一次帯電工程に次いで、発光素子からの露光１１１によって感光体１０９上に情報信号に応じた静電潜像を形成し、トナー担持体１０２と当接する領域においてトナーにより静電潜像を現像し可視像化する。さらに、本発明の画像形成方法において、特に感光体上にデジタル潜像を形成した現像システムと組み合わせることで、潜像を乱さないためにドット潜像に対して忠実に現像することが可能となる。次に、該可視像を転写部材１０６により非転写体１０５上に転写し、更に転写トナー１１２は被転写体１０５と共に加熱ローラ１０８と加圧ローラ１０７の間を通過して定着され、永久画像を得る。なお、加熱加圧定着手段としては、ここに示したハロゲンヒーターの如き発熱体を内蔵した加熱ローラとこれと押圧力をもって圧接された弾性体の加圧ローラを基本構成とする熱ローラ方式以外に、フィルムを介してヒーターにより加熱定着する方式も用いられる。
【０１４３】
一方、転写されずに感光体１０９上に残った転写残トナー１１３は、感光体１０９と一次帯電部材１１０の間を通過して、再び現像ニップ部に到達し、トナー担持体１０２によって現像器１００内に回収される。
【０１４４】
次に、中間転写体を用いた接触現像方式の、フルカラーでの画像形成方法について説明する。
【０１４５】
図２に示す装置システムにおいて、現像器２４−１、２４−２、２４−３、２４−４に、それぞれシアントナーを有する現像剤、マゼンタトナーを有する現像剤、イエロートナーを有する現像剤及びブラックトナーを有する現像剤が導入され、前述した現像方式等によって感光体１に形成された静電潜像を現像し、各色トナー像が感光体２１上に形成される。
【０１４６】
現像手段としては、例えば図３に示すような現像装置３１を具備する一成分系接触現像方式の現像手段を用い現像を行うことができる。具体的には、電源３６により直流あるいは交番電界をトナー担持体３７に印加しつつ、塗布ローラ３２より供給され、現像ブレード３３でコート量を規制されたトナー３４が感光体３５に接触している状態で現像を行なう。交番電界を用いる場合には、三角波、矩形波、正弦波、Ｄｕｔｙ比を変えた波形、定期的に交番をオフした波形を選択して用いることもできるが、本発明においては感光体への電圧的負荷の少ない直流電界が好適に使用され、印加電圧は感光体上の暗電位（帯電工程直後の電位）と明電位（露光工程後の電位）の間の適当な値に設定される。
【０１４７】
いずれの構成においても、トナー担持体の周速を感光体の周速に対し１．０５〜３．０倍となるように設定することが、より好ましい結果を与える。
【０１４８】
静電潜像担持体上のトナー画像は、電圧（例えば、±０．１〜±５ｋＶ）が印加されている中間転写体２５に一次転写され、転写残トナーは感光体と接するクリーニング手段２８でクリーニングされる。中間転写体表面は、クリーニングブレードを有するクリーニング手段２９でクリーニングされる。中間転写体上にトナー画像がある場合、トナー画像を乱さないようにクリーニング手段２９は、中間転写体表面から離される。
【０１４９】
中間転写体２５は、パイプ状の導電性芯金２５ｂと、その外周面に形成した中抵抗の弾性体層２５ａからなる。芯金２５ｂは、プラスチックのパイプに導電性メッキを施したものでも良い。
【０１５０】
中抵抗の弾性体層２５ａは、シリコーンゴム、テフロンゴム、クロロプレンゴム、ウレタンゴム、ＥＰＤＭ（エチレンプロピレンジエンの三元共重合体）などの弾性材料に、カーボンブラック、酸化亜鉛、酸化錫、炭化珪素の如き導電性付与剤を配合分散して電気抵抗値（体積抵抗率）を１０⁵ 〜１０¹¹Ω・ｃｍの中抵抗に調整した、ソリッドあるいは発泡肉質の層である。
【０１５１】
中間転写体２５は、静電潜像担持体２１に対して並行に軸受けさせて静電潜像担持体２１の下面部に接触させて配設してあり、静電潜像担持体２１と同じ周速度で矢印の反時計方向に回転する。
【０１５２】
静電潜像担持体２１の面に形成担持された第一色のトナー画像が、静電潜像担持体２１と中間転写体２５とが接する転写ニップ部を通過する過程で中間転写体２５の外面に対して順次に中間転写されていく。記録材へのトナー画像の転写後に、着脱自在なクリーニング手段２９により、中間転写体２５の表面がクリーニングされる。
【０１５３】
中間転写体２５に対して並行に軸受けさせて中間転写体２５の下面部に接触させて転写手段２７が配設され、転写手段２７は例えば転写ローラまたは転写ベルトであり、中間転写体２５と同じ周速度で矢印の時計方向に回転する。転写手段２７は直接中間転写体２５と接触するように配設されていてもよく、或いは、ベルトが中間転写体２５と転写手段２７との間に接触するように配置されても良い。
【０１５４】
転写ローラの場合、中心の芯金２７ｂとその外周を形成した導電性弾性層２７ａとを基本構成とするものである。
【０１５５】
中間転写体および転写ローラとしては、一般的な材料を用いることが可能である。中間転写体の弾性層の体積固有抵抗値をより小さく設定することで転写ローラへの印加電圧が軽減でき、転写材上に良好なトナー画像を形成できると共に転写材の中間転写体への巻き付きを防止することができる。特に中間転写体の弾性層の体積固有抵抗値が転写ローラの弾性層の体積固有抵抗値より１０倍以上であることが特に好ましい。
【０１５６】
例えば、転写ローラ２７の導電性弾性層２７ｂはカーボンの如き導電材を分散させたポリウレタン、エチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）の如き体積抵抗１０⁶ 〜１０¹⁰Ω・ｃｍ程度の弾性体でつくられている。芯金７ａには低電圧電源によりバイアスが印加されている。バイアス条件としては、±０．２〜１０ｋＶが好ましい。
【０１５７】
上述した接触現像方式を用い、現像兼クリーニングを行う場合に、感光体を一次帯電するための帯電手段として、帯電部材を感光体に当接させる接触帯電法を使用する場合、一般のトナーを使った場合、クリーニングの後の残トナーが後工程である接触帯電部材に付着すると、帯電不良を引き起こし、画像上に帯電ムラが発生する。従って、帯電手段が感光体に接することのないコロナ放電等に比べて、転写残トナーの量をより少なくする必要がある。従って、直接帯電法においては、ＳＦ−１、ＳＦ−２、（ＳＦ−２）／（ＳＦ−１）を前述した範囲に厳密に規定したトナーを使うことが好ましい。
【０１５８】
本発明に係わるトナーは、トナー粒子の表面形状を制御することにより、転写工程での転写効率が高く、転写残が少ないため、現像装置での現像兼クリーニングの際にクリーニング性に優れており、加えて、強靭なポリカーボネート系樹脂を含有しているので、接触帯電部材、感光体ドラム及び中間転写体上にフィルミングを生じにくい。さらに、多数枚耐久試験を行っても従来のトナーを使用した場合よりも、本発明のトナーにおいては外添剤のトナー粒子表面への埋没が少ないため、良好な画質を長期に渡って維持し得る。
【０１５９】
次いで転写材２６上のトナー画像は加熱加圧定着手段によって定着され、永久画像を得る。
【０１６０】
【実施例】
以下、具体的実施例によって本発明を説明するが、本発明は何らこれに限定されるものではない。
【０１６１】
樹脂（１）の製造例
反応容器にキシレン２００重量部を入れ還流温度まで昇温した。これにスチレン８５重量部、アクリル酸−ｎ−ブチル１５重量部、及び、ジ−ｔｅｒｔ−ブチルパーオキサイド２重量部の混合液を滴下後、キシレン還流下、７時間で溶液重合を完了し、低分子量樹脂溶液を得た。
【０１６２】
一方、スチレン７０重量部、アクリル酸ブチル２５重量部、マレイン酸モノブチル５重量部、ポリビニルアルコール０．２重量部、脱気水２００重量部、過酸化ベンゾイル０．１重量部を混合懸濁分散させた。上記懸濁分散溶液を加熱し、窒素雰囲気下において８５℃に２４時間保持して重合を完結させ、高分子量樹脂を得た。
【０１６３】
該高分子量樹脂３０重量部を前記の低分子量樹脂７０重量部を含有する溶液重合終了時の溶液中に投入し、溶媒中に完全に溶解せしめ混合を行い、その後、溶媒を留去して樹脂（１）を得た。
【０１６４】
得られた樹脂（１）を分析したところ、ＧＰＣによる分子量分布において、低分子量側ピーク分子量は１００００、高分子量側ピーク分子量は７５００００、重量平均分子量（Ｍｗ）は３６００００、数平均分子量（Ｍｎ）は６０００、Ｍｗ／Ｍｎは６０であり、さらにガラス転移温度（Ｔｇ）は６０℃であった。
【０１６５】
〔トナーの製造例〕
トナーの製造例１
・樹脂（１） １００重量部
・１，１−ビス（４−ヒドロキシフェニルシクロヘキサンポリカーボネート（ピーク分子量：５０００，Ｍｗ：６０００，Ｍｎ：２５００） １０重量部
・カーボンブラック（着色剤） ５重量部
・負電荷性制御剤（モノアゾ染料と鉄との化合物） ２重量部
・低分子量ポリエチレン（ＤＳＣピーク１０７℃） ５重量部
【０１６６】
上記材料をあらかじめ混合し、二軸押し出し機にて１３０℃で溶融混練を行った。この溶融混練物をハンマーミルにて粗砕し、１ｍｍメッシュパスのトナー粗砕物を得た。さらにこの粗砕物をジェット気流を利用した衝突式粉砕機で微粉砕した後、風力分級し、重量平均粒径９．３μｍの黒色粉（トナー粒子）（１）を得た。得られたトナー粒子（１）１００重量部に対して、ＢＥＴ法による比表面積が２００ｍ² ／ｇであるシリカ母体の表面をシランカップリング剤及びシリコーンオイルで疎水化処理して比表面積が１２０ｍ² ／ｇとなっている疎水性シリカを１．０重量部外添し、粉砕トナー（１）を得た。得られたトナー粒子及びトナーの諸物性を表１に示した。
【０１６７】
トナー（１）は、表１に示す通り、ＴＨＦ可溶分のＧＰＣによる分子量分布において、分子量１０００以下の成分をＧＰＣにより分取し、これを¹ Ｈ−ＮＭＲ、¹³Ｃ−ＮＭＲ及びＩＲにて分析を行ったところ、分子量１０００以下の成分中に含まれているポリカーボネート系樹脂の繰り返し単位を構造中に有する成分の含有量は、トナーの重量を基準として１．０重量％であった。
【０１６８】
トナー（１）の製造に用いた１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０１６９】
さらに、このトナーの断層面をＴＥＭ観察したところ、ポリカーボネート系樹脂及び低分子量ポリエチレンの非相溶の島状分散物がトナー全体に分散している様子が観察された。
【０１７０】
トナーの製造例２
トナーの製造例１で得られたトナー粒子（１）を、界面活性剤を含有する水溶液中に添加し、高速で撹拌しながら８５℃で２時間表面処理した後、ろ過、水洗、乾燥をして、重量平均径約９．６μｍの黒色粉（トナー粒子）（２）を得た。このトナー粒子（２）１００重量部に対して、重合トナーの製造例１で使用した疎水性シリカを１．０重量部外添し、球形化トナー（２）を得た。得られたトナー粒子及びトナーの諸物性を表１に示した。
【０１７１】
トナーの製造例３
低分子量ポリエチレンを用いず、トナーの製造例２と同様にして、トナー粒子（３）及び球形化トナー（３）を得た。得られたトナー粒子及びトナーの諸物性を表１に示す。
【０１７２】
トナーの製造例４
ポリカーボネート系樹脂（１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート）を用いず、他はトナーの製造例２と同様にして、トナー粒子（４）及び球形化トナー（４）を得た。得られたトナー粒子及びトナーの諸物性を表１に示す。
【０１７３】
トナーの製造例５
ポリカーボネート系樹脂（１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート）を４５重量部用いる以外は、トナーの製造例２と同様にして、トナー粒子（５）及び球形化トナー（５）を得た。得られたトナー粒子及びトナーの諸物性を表１に示す。
【０１７４】
トナーの製造例６
ピーク分子量が３５００、Ｍｗが４０００及びＭｎが１８００の１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートを用いる以外はトナーの製造例２と同様にして、トナー粒子（６）及び球形化トナー（６）を得た。
【０１７５】
トナー（６）の製造に用いた、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０１７６】
得られたトナー粒子及びトナーの諸物性を表１に示す。
【０１７７】
トナーの製造例７
樹脂（１）に代えて、スチレン−ブタジエン共重合体（Ｍｗ：１６３０００，Ｍｎ：１８３００，Ｍｗ／Ｍｎ：８．９）を用いて、トナーの製造例１と同様にして黒色分級粉を得た。得られた黒色分級粉を、界面活性剤を含有する水溶液中に添加し、高速で撹拌しながら９０℃で２時間表面処理した後、ろ過、水洗、乾燥をして、重量平均径約１０．５μｍのトナー粒子（７）を得た。このトナー粒子（７）１００重量部に対して、トナーの製造例１で使用した疎水性シリカを１．０重量部外添し、球形化トナー（７）を得た。得られたトナー粒子及びトナーの諸物性を表１に示した。
【０１７８】
トナーの製造例８
・樹脂（１） １００重量部
・カーボンブラック（着色剤） ５重量部
・負電荷性制御剤（モノアゾ染料と鉄との化合物） ２重量部
・低分子量ポリエチレン（ＤＳＣピーク１０７℃） ５重量部
【０１７９】
上記原材料を用い、トナーの製造例２と同様にして黒色粉を得た。得られた黒色粉１００重量部と微粉末状の１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート１０重量部をヘンシェルミキサーにて乾式混合した後、奈良機械社製ハイブリダイザーを用いて表面改質を行い、トナー粒子（８）を得、これを球形化トナー（８）とした。
【０１８０】
トナー（８）の製造に用いた、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０１８１】
このトナーの断層面をＴＥＭ観察したところ、ポリカーボネート系樹脂からなると思われる層が表面に観察され、低分子量ポリエチレンと思われる非相溶の島状分散物がトナー内部に分散している様子が観察された。得られたトナー粒子及びトナーの諸物性を表１に示した。
【０１８２】
トナーの製造例９
・樹脂（１） ５０重量部
・１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート（ピーク分子量：３０００，Ｍｗ：３５００，Ｍｎ：１０００） ５０重量部
・カーボンブラック（着色剤） ５重量部
・負電荷性制御剤（モノアゾ染料と鉄との化合物） ２重量部
・低分子量ポリエチレン（ＤＳＣピーク１０７℃） ５重量部
【０１８３】
上記材料をあらかじめ混合し、二軸押し出し機にて１３０℃で溶融混練を行った。この溶融混練物をハンマーミルにて粗砕し、１ｍｍメッシュパスのトナー粗砕物を得た。さらにこの粗砕物をジェット気流を利用した衝突式粉砕機で微粉砕した後、風力分級し、重量平均粒径９．３μｍの黒色粉（トナー粒子）（９）を得た。得られたトナー粒子（９）１００重量部に対して、ＢＥＴ法による比表面積が２００ｍ² ／ｇであるシリカ母体の表面をシランカップリング剤及びシリコーンオイルで疎水化処理して比表面積が１２０ｍ² ／ｇとなっている疎水性シリカを１．０重量部外添し、粉砕トナー（９）を得た。
【０１８４】
トナー粒子（９）の製造に用いた１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートは、再沈殿による精製をしなかったものである。
【０１８５】
得られたトナー粒子及びトナーの諸物性を表１に示す。
【０１８６】
トナーの製造例１０
２リットル用四つ口フラスコ中のイオン交換水７１０ｇに、０．１Ｍ−Ｎａ₃ ＰＯ₄ 水溶液５６０ｇを投入し、６０℃に加温した後、高速攪拌装置ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂ 水溶液８５ｇを徐々に添加し、微小な難水溶性分散安定剤を含む水系分散媒体を得た。
【０１８７】
一方、分散質として
・スチレン ８０重量部
・ｎ−ブチルアクリレート ２０重量部
・カーボンブラック（着色剤） ５重量部
・１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート（ピーク分子量：５０００，Ｍｗ：６０００，Ｍｎ：２６００） ５重量部
・カーボンブラック ５重量部
・負電荷性制御剤（モノアゾ染料と鉄との化合物） ２重量部
・エステルワックス（ＤＳＣピーク７０℃）５重量部
【０１８８】
上記処方のうち、着色剤とモノアゾ染料のＦｅ化合物とスチレンだけをアトライター（三井金属社製）を用いてカーボンブラックのマスターバッチ製造を行った。次にこのマスターバッチと上記処方の残りの材料を６０℃に加温し、溶解、分散して単量体混合物とした。さらに、６０℃に保持しながら、開始剤２，２′−アゾビス（２，４−ジメチルバレロニトリル）１０ｇを加えて溶解し、単量体組成物を調製した。
【０１８９】
前記ホモミキサーの２リットルフラスコ中で調製した水系分散媒体に、上記単量体組成物を投入した。６０℃で、窒素雰囲気としたＴＫホモミキサーを用いて、１００００ｒｐｍで２０分間撹拌し、単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ６０℃で６時間反応させた後、８０℃で１０時間重合させた。
【０１９０】
重合反応終了後反応生成物を冷却し、塩酸を加えてＣａ₃ （ＰＯ₄ ）₂ を溶解し、濾過、水洗、乾燥することにより、重量平均径約７．１μｍの黒色懸濁粒子（トナー粒子）（１０）を得た。
【０１９１】
得られたトナー粒子（１０）１００重量部に対して、トナーの製造例１で使用した疎水性シリカを１．５重量部外添し、重合トナー（１０）を得た。
【０１９２】
トナー（１０）の製造に用いた、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０１９３】
このトナーの断層面をＴＥＭ観察したところ、ポリカーボネート系樹脂からなる層が表面に観察され、低分子量ポリエチレンからなる球状分散物がトナー内部に分散している様子が観察された。
【０１９４】
得られたトナー粒子及び重合トナーの諸物性を表１に示した。
【０１９５】
トナーの製造例１１
エステルワックスを５０重量部用いる以外はトナーの製造例１０と同様にして、トナー粒子（１１）及び重合トナー（１１）を得た。
【０１９６】
得られたトナー粒子及び重合トナーの諸物性を表１に示した。
【０１９７】
トナーの製造例１２
ポリカーボネート系樹脂（１，１−ビス（４−ヒドロキシフェニル）シクロヘキサンポリカーボネート）を用いず、他はトナーの製造例１０と同様にして、トナー粒子（１２）及び重合トナー（１２）を得た。
【０１９８】
得られたトナー粒子及び重合トナーの諸物性を表１に示した。
【０１９９】
トナーの製造例１３
２リットル用四つ口フラスコ中のイオン交換水７１０ｇに、０．１Ｍ−Ｎａ₃ ＰＯ₄ 水溶液５６０ｇを投入し、６０℃に加温した後、高速撹拌装置ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂ 水溶液８５ｇを徐々に添加し、微小な難水溶性分散安定剤を含む水系分散媒体を得た。
【０２００】
一方、分散質として
・スチレン ８０重量部
・ｎ−ブチルアクリレート ２０重量部
・ビスフェノールＡ−ビフェノール−ヘキサメチレングリコール共重合ポリカーボネート（ピーク：分子量３００００，Ｍｗ：４２０００，Ｍｎ：１６０００）５重量部
・Ｃ．Ｉ．ピグメントブルー１５：３（着色剤） ５重量部
・荷電制御剤（２，５−ジ−ｔｅｒｔ−ブチルサリチル酸のＡｌ化合物） ２重量部
・エステルワックス（ＤＳＣピーク７０℃） ５重量部
【０２０１】
上記処方のうち、着色剤とジ−ｔ′ｅｒｔ−ブチルサリチル酸のＡｌ化合物とスチレンだけをエバラマイルダー（荏原製作所製）を用いて予備混合を行った。次に上記処方すべてを６０℃に加温し、溶解、分散して単量体混合物とした。さらに、６０℃に保持しながら、開始剤２，２′−アゾビス（２，４−ジメチルバレロニトリル）１０ｇを加えて溶解し、単量体組成物を調製した。
【０２０２】
前記ホモミキサーの２リットルフラスコ中で調製した水系分散媒体に、上記単量体組成物を投入した。６０℃で、窒素雰囲気としたＴＫホモミキサーを用いて、１００００ｒｐｍで２０分間撹拌し、単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ６０℃で６時間反応させた後、８０℃で１０時間重合させた。
【０２０３】
重合反応終了後反応生成物を冷却し、塩酸を加えてＣａ₃ （ＰＯ₄ ）₂ を溶解し、濾過、水洗、乾燥することにより、重量平均径約６．９μｍの着色懸濁粒子（トナー粒子）（１３）を得た。
【０２０４】
得られたトナー粒子（１３）１００重量部に対して、トナーの製造例１で用いた疎水性シリカを１．５重量部外添し、重合トナー（１３）を得た。
【０２０５】
トナー（１３）の製造に用いたビスフェノールＡ−ビフェノール−ヘキサメチレングリコール共重合ポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０２０６】
得られたトナー粒子及び重合トナーの諸物性を表１に示した。
【０２０７】
トナーの製造例１４
２リットル用四つ口フラスコ中のイオン交換水７１０ｇに、０．１Ｍ−Ｎａ₃ ＰＯ₄ 水溶液５２０ｇを投入し、６０℃に加温した後、高速撹拌装置ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂ 水溶液８５ｇを徐々に添加し、微小な難水溶性分散安定剤を含む水系分散媒体を得た。
【０２０８】
一方、分散質として
・スチレン ８０重量部
・ｎ−ブチルアクリレート ２０重量部
・１−フェニル−１，１−ビス（４−ヒドロキシフェニル）エタンポリカーボネート（ピーク分子量：２００００，Ｍｗ：３２０００，Ｍｎ：１００００） ５重量部
・Ｃ．Ｉ．ピグメントレッド２０２（着色剤） ５重量部
・荷電制御剤（２，５−ジ−ｔｅｒｔ−ブチルサリチル酸のＡｌ化合物） ２重量部
・エステルワックス（ＤＳＣピーク７０℃）５重量部
【０２０９】
上記処方のうち、着色剤とジ−ｔｅｒｔ−ブチルサリチル酸のＡｌ化合物とスチレンだけをエバラマイルダー（荏原製作所製）を用いて予備混合を行った。次に上記処方すべてを６０℃に加温し、溶解、分散して単量体混合物とした。さらに、６０℃に保持しながら、開始剤２，２′−アゾビス（２，４−ジメチルバレロニトリル）１０ｇを加えて溶解し、単量体組成物を調製した。
【０２１０】
前記ホモミキサーの２リットルフラスコ中で調製した分散媒体に、上記単量体組成物を投入した。６０℃で、窒素雰囲気としたＴＫホモミキサーを用いて、１００００ｒｐｍで２０分間撹拌し、単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ６０℃で６時間反応させた後、８０℃で１０時間重合させた。
【０２１１】
重合反応終了後反応生成物を冷却し、塩酸を加えてＣａ₃ （ＰＯ₄ ）₂ を溶解し、濾過、水洗、乾燥することにより、重量平均径約７．１μｍの着色懸濁粒子（トナー粒子）（１４）を得た。
【０２１２】
得られたトナー粒子（１４）１００重量部に対して、トナーの製造例１で用いた疎水性シリカを１．５重量部外添し、重合トナー（１４）を得た。
【０２１３】
トナー（１４）の製造に用いた１，１−ビス（４−ヒドロキシフェニル）エタンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０２１４】
得られたトナー粒子及び重合トナーの諸物性を表１に示した。
【０２１５】
トナーの製造例１５
分散質として以下の内容のものを用いた。
・スチレン ８０重量部
・ｎ−ブチルアクリレート ２０重量部
・２，２−ビス（３−メチル−４−ヒドロキシフェニル）プロパンポリカーボネート（ピーク分子量：８０００，Ｍｗ：１２０００，Ｍｎ：４０００） ５重量部
・Ｃ．Ｉ．ピグメントイエロー１７（着色剤） ５重量部
・荷電制御剤（２，５−ジ−ｔｅｒｔ−ブチルサリチル酸のＡｌ化合物） ２重量部
・エステルワックス（ＤＳＣピーク７０℃）５重量部
【０２１６】
上記処方内容で、トナーの製造例１３と同様の手法により、トナー粒子（１５）を製造し、同様にして重量平均径約７．０μｍの重合トナー（１５）を得た。
【０２１７】
トナー（１５）の製造に用いた２，２−ビス（３−メチル−４−ヒドロキシフェニル）プロパンポリカーボネートは、ジクロロメタンとイソプロパノールを用いて再沈殿をくり返し低分子量成分及び不純物が減少するように精製したものである。
【０２１８】
得られた重合トナー（１５）の諸物性を表１に示した。
【０２１９】
【表１】

【０２２０】
〈実施例１〜３、５〜１１，比較例１〜３，参考例１〜２〉
電子写真装置として６００ｄｐｉレーザービームプリンタ（キヤノン製：ＬＢＰ−８６０）を用意した。プロセススピードは、６０ｍｍ／ｓに改造してある。
【０２２１】
このプロセスカートリッジにおけるクリーニングゴムブレードを取りはずし、装置の帯電方式をゴムローラを当接して行う直接帯電とし、印加電圧を直流成分（−１２００Ｖ）とした。
【０２２２】
次に、プロセスカートリッジにおける現像部分を改造した。トナー供給体であるステンレススリーブの代わりにカーボンブラックを分散したシリコーンゴムからなる中抵抗ゴムローラ（１６φ、硬度ＡＳＫＥＲ Ｃ４５度、抵抗１０⁵ Ω・ｃｍ）をトナー担持体とし、感光体に当接した。この時の現像ニップ幅は約３ｍｍとなるようにした。該トナー担持体の回転周速は、感光体との接触部分において同方向であり、該感光体回転周速に対し１５０％となるように駆動する。
【０２２３】
ここで用いる感光体としては、３０φ、２５４ｍｍのＡｌシリンダーを基体としたもので、これに、以下に示すような構成の層を順次浸漬塗布により積層して、感光体を作製した。
（１）導電性被覆層：酸化錫及び酸化チタンの粉末をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
（２）下引き層：変性ナイロン、及び共重合ナイロンを主体とする。膜厚０．６μｍ。
（３）電荷発生層：長波長域に吸収を持つチタニルフタロシアニン顔料をブチラール樹脂に分散したものを主体とする。膜厚０．６μｍ。
（４）電荷輸送層：ホール搬送性トリフェニルアミン化合物をポリカーボネート樹脂（オストワルド粘度法による分子量２万）に８：１０の重量比で溶解したものを主体とする。膜厚２０μｍ。
【０２２４】
トナー担持体にトナーを塗布する手段として、現像器内に発泡ウレタンゴムからなる塗布ローラを設け、該トナー担持体に当接させた。塗布ローラには、約−５５０Ｖの電圧を印加する。さらに、該トナー担持体上のトナーのコート層制御のために樹脂をコートしたステンレス製ブレードを、トナー担持体との接触圧が線圧約２０ｇ／ｃｍとなるように取付けた。概略を図１に示す。また、現像時の印加電圧をＤＣ成分（−４５０Ｖ）のみとした。
【０２２５】
これらのプロセスカートリッジの改造に適合するよう電子写真装置に以下のように改造及びプロセス条件設定を行った。
【０２２６】
改造された装置はローラ帯電器（直流のみを印加）を用い像担持体を一様に帯電する。帯電に次いで、レーザー光で画像部分を露光することにより静電潜像を形成し、トナーにより可視画像とした後に、電圧を印加したローラによりトナー像を転写材に転写するプロセスを持つ。概略を図１に示した。
【０２２７】
感光体帯電電位は、暗部電位を−６００Ｖとし、明部電位を−１５０Ｖとした。転写材としては、７５ｇ／ｍ² の紙を用いた。
【０２２８】
上記の画像形成装置により、表２で示す通り粉砕トナー（１）及び（９）、球形化トナー（２）〜（８）、及び重合トナー（１０）〜（１５）を用いて、温度１０℃／湿度１０％の条件下で耐久試験を行った。
【０２２９】
耐久性評価は印字面積比率３％で文字印刷を行い、以下のように評価した。
【０２３０】
トナーの帯電ローラ汚染は、ハーフトーン画像上に帯電部材汚染による帯電ムラが発生した枚数で判断した。
【０２３１】
トナーの感光体融着及びスリーブ融着は、ベタ黒画像上に白抜けが発生した段階で感光体表面及びスリーブ表面を観察し、融着の有無を確認した。融着が観察されなければ耐久性評価を継続した。
【０２３２】
帯電ローラ汚染、感光体融着及びスリーブ融着が発生しない場合１５００枚まで画像印刷を続けた。発生した枚数が多い程、トナーの耐久性が良好なことを意味する。
【０２３３】
耐久処理の転写性は、ベタ黒画像現像時の感光体上の転写残トナーをマイラーテープによりテーピングしてはぎ取り、紙上に貼ったもののマクベス濃度から、テープのみを貼ったもののマクベス濃度を差し引いた数値で評価した。従って、値の小さいほど転写性は良好である。
【０２３４】
耐久初期の解像力は潜像電界によって電界が閉じやすく、再現しにくい６００ｄｐｉにおける小径孤立１ドットの再現性によって評価した。
◎（非常に良好）：１００個中の欠損が５個以下
○（良好）：１００個中の欠損が６〜１０個
△（普通）：１００個中の欠損が１１〜２０個
×（悪い）：１００個中の欠損が２０個以上
【０２３５】
耐オフセット性は、初期から耐久１００枚までの画像サンプルの裏側に発生する汚れを観察し、発生枚数を数えた。
【０２３６】
カブリの測定は、東京電色社製のＲＥＦＬＥＣＴ ＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳを使用して測定した。
【０２３７】
フィルターは、重合トナー（１３）にはアンバーライトフィルターを、重合トナー（１５）にはブルーフィルターを、その他のトナーにはグリーンフィルターを用い、下記式より算出した。数値が小さい程、カブリが少ない。
【０２３８】
カブリ量（％）＝（プリントアウト前の白色度）−（プリント後の記録材の非画像形成部（白地部）の白色度）
【０２３９】
得られた結果を表２に示す。
【０２４０】
【表２】

【０２４１】
〈実施例１３及び比較例４〉
以下に示す実験条件にて、フルカラー画像での耐久評価を行った。
【０２４２】
図２は本実施例１２及び比較例４に適用される画像形成装置の断面の概略図であり、図３は画像形成装置の現像装置図である。
【０２４３】
感光体ドラム２１は、基材２１ａ上に有機光半導体を有する感光層２１ｂを有し、矢印方向に回転し、対向し接触回転する帯電ローラ２２（導電性弾性層２２ａ，芯金２２ｂ）により感光体ドラム２１上に約−６００Ｖの表面電位に帯電させる。露光２３において、ポリゴンミラーにより感光体上にデジタル画像情報に応じてオン−オフさせることで露光部電位が−１００Ｖ、暗部電位が−６００Ｖの静電荷像が形成される。現像器２４−１、２４−２、２４−３、２４−４に、それぞれ重合トナー（１３）、重合トナー（１４）、重合トナー（１５）、及び重合トナー（１０）または（１４）が導入され、非磁性一成分方式によって感光体２１に形成された静電潜像を反転現像し、各色トナー像が感光体２１上に形成される。該トナー像は各色毎の現像後順次中間転写体２５上に一次転写され、最後に記録材２６上に一括して二次転写される。この時、転写されずに感光体２１上に残ったトナーはクリーナー部材２８でクリーニングされ、中間転写体２５上に残ったトナーはクリーナー部材２９でクリーニングされる。
【０２４４】
中間転写体２５は、パイプ状の芯金２５ｂ上にカーボンブラックの導電付与部材をニトリル−ブタジエンラバー（ＮＢＲ）中に充分分散させた弾性層２５ａをコーティングしたものであり、該コート層２５ａの硬度は「ＪＩＳ Ｋ−６３０１」に準拠し２０度で、かつ体積固有抵抗値は１０⁹ Ω・ｃｍである。感光体２１から中間転写体２５への転写に必要な転写電流は約５μＡであり、これは電源より＋１０００Ｖを芯金２５ｂ上に付与することで得られた。
【０２４５】
転写ローラ２７の外径は２０ｍｍであり、該転写ローラ２７は直径１０ｍｍの芯金２７ｂ上にカーボンの導電性付与部材をエチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）の発泡体中に充分分散させたものをコーティングすることにより生成した弾性層２７ａを有し、弾性層２７ａの体積固有抵抗値は１０⁶ Ω・ｃｍで、「ＪＩＳ Ｋ−６３０１」の基準の硬度は３５度の値を示すものを用いた。転写ローラには電圧を印加して１５μＡの転写電流を流した。
【０２４６】
加熱定着装置Ｈにはオイル塗布機能のない熱ロール方式の定着装置を用いた。
【０２４７】
以上の設定条件で、温度３０℃／湿度８０％の条件下、印字面積１０％の画像を８枚／分（Ａ４サイズ）の通紙速度で、最長で連続１５００枚の耐久評価を行った。
【０２４８】
トナーの感光体融着及びスリーブ融着は、実施例１〜１２と同様に評価した。中間転写体上の融着は、ベタ黒画像上に白抜けが発生した段階で中間転写体表面を観察し、融着の有無を確認した。融着が観察されなければ耐久性評価を継続した。
【０２４９】
帯電ローラ汚染、感光体融着及びスリーブ融着が発生しない場合１５００枚まで画像印刷を続けた。発生した枚数が多い程、トナーの耐久性が良好なことを意味する。
【０２５０】
以上の評価結果を表３にまとめる。
【０２５１】
【表３】

【０２５２】
【発明の効果】
以上説明したように、本発明の画像形成方法によれば、定着性を損なわずに、接触現像方式における優れた耐久性が得られる。特に、クリーナレス構成、中間転写体を用いる構成に適用すれば、優れた現像性、転写性、耐トナー融着性を長期間安定が得られる。
【図面の簡単な説明】
【図１】本発明に好適な一成分画像形成装置の概略図である。
【図２】本発明に好適な中間転写体を用いたフルカラー用画像形成装置の概略図である。
【図３】本発明に好適な現像装置の概略的説明図である。
【符号の説明】
２１ 感光体（静電潜像担持体）
２４ 現像器
２５ 中間転写体
２６ 転写材
２７ 転写手段
３１ 現像装置
３４ 現像剤
３５ 感光体
３７ 現像剤担持体
１００ 現像装置
１０２ トナー担持体
１０４ トナー
１０５ 転写材
１０６ 転写部材
１０９ 感光体（静電荷像担持体）
１１０ 一次帯電部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method for developing an electrostatic latent image in an electrophotographic method or an electrostatic recording method.
[0002]
[Prior art]
Conventionally, electrophotographic methods are known in a number of ways as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is developed with toner, and direct or indirect means are used as necessary. After the toner image is transferred to a recording material such as paper, it is fixed by heating, pressing or solvent vapor to obtain a copy. The untransferred toner remaining without being transferred onto the photoreceptor is cleaned by various methods, and the above-described steps are repeated.
[0003]
An example of a general method for forming a full-color image will be described. A laser in which a photoreceptor (electrostatic latent image carrier) of a photoreceptor drum is uniformly charged by a primary charger and modulated by a magenta image signal of an original. Image exposure is performed with light, an electrostatic latent image is formed on the photosensitive drum, and the electrostatic latent image is developed by a magenta developer holding magenta toner to form a magenta toner image. Next, the magenta toner image developed on the photosensitive drum by the transfer charger is transferred onto the conveyed recording material using direct or indirect means.
[0004]
After the development of the electrostatic latent image, the photosensitive drum is neutralized by a neutralizing charger, cleaned by a cleaning unit, charged again by a primary charger, and similarly a cyan toner image is formed. Then, a cyan toner image is formed on the recording material to which the magenta toner image is transferred, and the toner images of four colors are transferred to the recording material in the same manner as yellow and black. The recording material having the four color toner images is fixed by the action of heat and pressure by a fixing roller to form a full color image.
[0005]
In recent years, such apparatuses have begun to be used not only in office copy machines for copying original documents, but also in the fields of laser beam printers as computer outputs or personal copying for individuals.
[0006]
In addition to the fields represented by such laser beam printers and personal copying, the deployment of plain paper fax machines using basic engines is also rapidly developing.
[0007]
For this reason, miniaturization, weight reduction, high speed, high image quality, and high reliability have been pursued more severely, and machines are configured with simpler elements in various respects. . As a result, the performance required for the toner becomes higher, and if the improvement in the performance of the toner cannot be achieved, a better machine cannot be realized. In recent years, with the various copying needs, demand for color copying is rapidly increasing, and in order to copy original color images more faithfully, higher image quality and higher resolution without image defects are desired.
[0008]
From these viewpoints, the toner used in the color image forming method must have good meltability and color mixing when heated, and has a low softening point and a low melt viscosity. It is preferable to use a high toner.
[0009]
By using such sharp melt toner, the color reproduction range of the copy can be widened, and a color copy faithful to the original image can be obtained at a higher speed.
[0010]
However, such a high-melting color toner generally has a high affinity with the fixing roller and tends to be offset to the fixing roller during fixing.
[0011]
In particular, in the case of a fixing device in a color image forming apparatus, since a plurality of toner layers of magenta, cyan, yellow, and black are formed on a transfer material, an offset tends to easily occur due to an increase in toner layer thickness.
[0012]
Conventionally, for the purpose of preventing toner from adhering to the surface of the fixing roller, for example, a method of adding a release agent such as low molecular weight polyethylene or low molecular weight polypropylene to the toner has been proposed.
[0013]
For example, Japanese Patent Publication No. 52-3304, Japanese Patent Publication No. 52-3305, and Japanese Patent Application Laid-Open No. 57-52574 have disclosed a technique for incorporating a wax as a releasing agent in the toner.
[0014]
Also, JP-A-3-50559, JP-A-2-79860, JP-A-1-109359, JP-A-62-1166, JP-A-61-227354, JP-A-61-94062. Japanese Patent Laid-Open Nos. 61-138259, 60-252361, 60-252360, and 60-217366 disclose techniques for containing waxes. .
[0015]
However, in the case of a black toner, a release agent having a relatively high crystallinity represented by polyethylene wax or polypropylene wax can be used to improve the high temperature offset resistance at the time of fixing. Due to the crystallinity of the release agent, the transparency of the OHP toner image is significantly inhibited when it is output. Furthermore, the blocking resistance is deteriorated, the image forming apparatus such as a printer or a copying machine is exposed to heat due to the temperature rise in the apparatus, and when the toner is left for a long time, the wax migrates to the toner surface and develops. Or get worse.
[0016]
Various attempts have been made to improve these problems from the binder resin side. That is, high temperature offset resistance at the time of fixing is improved by increasing the cross-linking component or high molecular weight component in the binder resin.
[0017]
Certainly, according to this method, the high temperature offset resistance can be improved to some extent, and further, the durability can be improved such as burying the external additive in the toner surface and fusing to the photosensitive member and the toner carrier. It can be seen.
[0018]
However, this method is contrary to the improvement of toner pulverization property and low-temperature fixability, and there is still room for improvement in compatibility between high-temperature offset resistance and durability and low-temperature fixability.
[0019]
On the other hand, when the toner image formed on the photoconductor in the development process is transferred to the transfer material in the transfer process, if residual transfer toner remains on the photoconductor as described above, the toner is cleaned in the cleaning process and is used as waste toner. It needs to be stored in a container. Conventionally, blade cleaning, fur brush cleaning, and roller cleaning have been used for this cleaning process. In either method, the transfer residual toner is mechanically scraped off or damped and collected in a waste toner container. Therefore, there has been an unavoidable problem caused by such a member being pressed against the surface of the photoreceptor. For example, it is possible to wear the photosensitive member by pressing the member strongly to shorten the life of the photosensitive member. From the standpoint of the apparatus, since the apparatus is inevitably enlarged in order to have such a cleaning apparatus, it has become a bottleneck when aiming to make the apparatus compact. Furthermore, from the viewpoint of ecology, a system that does not generate waste toner is desired in the sense of effective use of toner.
[0020]
Here, technologies relating to cleanerless are disclosed in Japanese Patent Application Laid-Open Nos. 59-133573, 62-203182, 63-133179, and 64-20587. No. 2, JP-A-2-302277, JP-A-5-2289, JP-A-5-53482, and JP-A-5-61383, but a desirable toner configuration is not mentioned.
[0021]
Furthermore, in the development and cleaning configuration that essentially does not have a cleaning device, it is essential to have a configuration in which the surface of the photoreceptor is rubbed with toner and a toner carrier, and for this reason, toner degradation due to long-term use, toner carrier surface degradation, Deterioration of durability characteristics remains as a problem, causing deterioration of the photoreceptor surface or wear, etc., and conventional toners that emphasize fixability cannot be sufficiently solved. desired.
[0022]
In the non-magnetic one-component contact development method, the technology of a polymerized toner that has an effect of suppressing the surface deterioration of the toner carrier and the surface of the photoreceptor is disclosed in JP-A-7-281485. Is general and nothing is said about the influence from the resin composition. Furthermore, there is no description regarding compatibility with fixing properties.
[0023]
Conventionally, in a full-color copying machine, four photoreceptors and a belt-like transfer belt are used, and an electrostatic latent image formed on each photoreceptor is developed using cyan, magenta, yellow, and black toners, and then the photoreceptor and the belt. After transferring the transfer material between the transfer members and transferring it between straight paths, a full color image is formed, or the transfer material is wound around the surface of the transfer member facing the photosensitive member by mechanical action such as electrostatic force or gripper, and developed. -A method of obtaining a full-color image as a result of performing the transfer process four times is generally used.
[0024]
In recent years, there has been an increasing need for various materials to be developed on small-size paper such as cardboard, cards, and postcards in addition to ordinary paper and overhead projector film (OHP) as full-color copying materials. In the method using the four photoconductors described above, since the transfer material is conveyed straight, the application range to various transfer materials is wide. However, it is necessary to accurately superimpose a plurality of toner images on the position of a predetermined transfer material. Yes, it is difficult to obtain high-quality images with good reproducibility even with a slight difference in registration. The transfer material transport mechanism is complicated, leading to a decrease in reliability and an increase in the number of parts. There is a problem of doing. In addition, when using thick paper with a large amount of weight by adsorbing and winding the transfer material on the surface of the transfer body, the trailing edge of the transfer material causes poor adhesion due to the stiffness of the transfer material, resulting in an image based on transfer. It causes defects and is not preferable. Similarly, image defects may occur on small-size paper.
[0025]
Therefore, a process configuration using an intermediate transfer member has been proposed as a configuration that can be applied to various transfer materials and can be miniaturized. For example, a full-color image device using a drum-shaped intermediate transfer member is already known from US Pat. No. 5,187,526 and Japanese Patent Laid-Open No. 4-16426.
[0026]
However, in a full-color image forming apparatus that transfers a plurality of toner images, the amount of toner increases on the intermediate transfer body and inevitably increases the amount of residual toner, compared to the case of black and white. It becomes necessary to increase the displacement force and the rubbing force with the cleaning member. For this reason, when a color toner having good fixability is used, fusing and filming are likely to occur on the surface of the intermediate transfer member, transfer efficiency is deteriorated, and toner images of four colors are transferred uniformly in full color. As a result, problems in terms of color unevenness and color balance are likely to occur, and it has been difficult to stably output high-quality full-color images. That is, also in this step, a toner having a good balance between fixability and durability is desired.
[0027]
By the way, as one of resins excellent in mechanical strength, electrical characteristics, aging resistance (weather resistance) and the like, polycarbonate is generally widely known and used in various applications. Several methods using polycarbonate as a binder resin have been disclosed for toners for developing electrostatic images. For example, Japanese Patent Application Laid-Open No. 46-28588 discloses an image forming method using a specific polycarbonate copolymer and a granular carrier. According to this publication, a toner having excellent blocking resistance can be obtained by using a specific polycarbonate copolymer as a binder resin. However, in this publication, a polycarbonate copolymer having a glass transition temperature of 70 to 95 ° C. is used as a binder resin, and since no wax component is contained in the toner, the low-temperature fixability is very poor and there is room for improvement. . Further, there is no description of the influence of impurities contained in the polycarbonate copolymer on the electrophotographic characteristics and the like. Further, in this publication, toner production methods by spray drying method and pulverization method are disclosed in Examples. However, the toner image from the obtained toner shape is transferred from the electrostatic image carrier to the transfer material. There is no description about the difference in transferability or the difference in charging uniformity.
[0028]
JP-A-63-208863 discloses a method of using a polycarbonate terpolymer having a specific structure having a glass transition temperature of about 50 ° C. as a binder resin for a toner for flash fixing. According to this publication, a toner having excellent fixability despite the fact that the polycarbonate terpolymer, which is a binder resin, does not thermally decompose during flash fixing and thus does not contain odors or eluates and does not contain a wax component. Can be obtained. However, on the other hand, only polycarbonate terpolymers with a low glass transition temperature are used as binder resins, so they have not reached satisfactory levels of blocking resistance and durability. Therefore, it is difficult to apply the toner to a fixing device in which the toner comes into contact with a heating body such as heat roll fixing.
[0029]
Further, US Pat. No. 4,457,998 discloses a toner having a structure in which a linear binder resin is incorporated in a highly crosslinked binder resin. It is said that a polycarbonate copolymer can be used as a crosslinked binder resin, a linear binder resin, or both. However, this patent specification does not describe any example using a polycarbonate copolymer, and the effect when the polycarbonate copolymer is used as a binder resin is unclear.
[0030]
In Japanese Patent Laid-Open No. 5-273382, in an image forming method using a developing roller having a large number of minute closed electric fields formed in the vicinity of the surface, a toner whose plate has an Izod impact value of 2 to 500 kg · cm / cm. When used, it is disclosed that filming on the developing roller can be prevented, and it is described that a mixture of styrene-acrylic resin and polycarbonate can be used as a binder resin as the toner.
[0031]
However, there is no specific description about the polycarbonate in the publication, and in the molecular weight distribution by GPC, the component having a repeating unit of polycarbonate contained in a component having a molecular weight of 1000 or less, and the molecular weight of the polycarbonate are examined. It has not been.
[0032]
Japanese Patent Application Laid-Open No. 6-43688 describes a method in which a polycarbonate copolymer having a specific structure exhibiting a thermotropic liquid crystallinity is used as a binder resin. The polycarbonate copolymer exhibiting a thermotropic liquid crystallinity usually has high crystallinity, exhibits a gentle thermal softening behavior up to the melting point, and further liquefies (melts) as the temperature rises, causing the viscosity to drop and the temperature to decrease. In order to show the property of deteriorating, the toner using the polycarbonate copolymer as a binder resin can be fixed with low energy even without containing a wax component in the toner while maintaining grindability and anti-blocking property. . However, since the toner according to the publication is composed of only one kind of binder resin, the viscosity at the time of melting the toner is too low, and a so-called high-temperature offset occurs in which the molten toner adheres to a fixing device such as a heat roll. The problem is not solved. Further, there is no specific description regarding the influence of impurities contained in the polycarbonate copolymer on the electrophotographic characteristics and the like, and the shape of the toner.
[0033]
There has been proposed a possibility of solving the above-mentioned various problems by suspension polymerization toner (Japanese Patent Publication No. 36-10231). In this suspension polymerization method, a monomer composition is prepared by uniformly dissolving or dispersing a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives). Then, the monomer composition is dispersed in a continuous phase (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and simultaneously subjected to a polymerization reaction, whereby toner particles having a desired particle size are obtained. Is what you get.
[0034]
In this suspension polymerization method, droplets of the monomer composition are generated in a dispersion medium having a large polarity such as water. Therefore, the component having a polar group contained in the monomer composition is an interface with the aqueous phase. Therefore, it is possible to form a so-called core / shell structure in which a nonpolar component is not easily present in the surface layer portion. That is, the toner produced by the polymerization method can satisfy the conflicting performances of low-temperature fixability, blocking resistance and durability, and high-temperature offset resistance by encapsulating the wax component as a release agent.
[0035]
If the advantages of the polycarbonate resin described above are incorporated into this polymerized toner and used under a cleaner-less configuration or a configuration using an intermediate transfer member, there is a possibility that a significant downsizing of the image forming apparatus can be achieved.
[0036]
In JP-A-8-305074, a cleanerless image forming method using a toner having a specific shape with a residual monomer of 1000 ppm or less is described. However, toner fusion to the surface of a photoreceptor or a toner carrier is described. There was room for further improvement.
[0037]
[Problems to be solved by the invention]
An object of the present invention is to use a special toner, and in a contactless development image forming process using a cleaner-less structure or an intermediate transfer member, durability such as resistance to toner deterioration and toner fusion resistance is maintained while maintaining low-temperature fixability. It is an object of the present invention to provide an image forming method capable of greatly improving the image quality.
[0038]
[Means for Solving the Problems]
The above object is achieved by the following configurations of the present invention.
[0039]
  The present invention relates to a charging step of charging an electrostatic latent image carrier; an exposure step of forming an electrostatic latent image on the charged electrostatic latent image carrier by exposure; the surface of the electrostatic latent image carrier and a toner carrier A developing step of contacting the toner layer formed by the toner carried on the body and developing the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image; and A transfer step of transferring a toner image formed on the electrostatic latent image carrier onto a transfer material;A fixing step of fixing the toner image transferred onto the transfer material by applying pressure and heat to the transfer material;In an image forming method havingThe toner carrier has an elastic layer on the surface,The toner contains at least a binder resin, a colorant, and a wax, and the binder resin contains at least a polycarbonate resin.The polycarbonate-based resin has a peak molecular weight in the region of molecular weight 2000 to 100,000 in the molecular weight distribution by gel permeation chromatography (GPC) soluble in tetrahydrofuran (THF), and the toner can be tetrahydrofuran (THF). 4. In a molecular weight distribution by gel permeation chromatography (GPC) of a solute, a component having a repeating unit of a polycarbonate-based resin contained in a component having a molecular weight of 1000 or less in the structure is based on the weight of the toner. Contains up to 0% by weightThe present invention relates to an image forming method.
[0040]
As a result of intensive investigations against the background of the prior art described above, the present inventors have found that polycarbonate is used as a part of a binder resin in an image forming method using a contact development method in which toner deterioration and toner fusion are likely to occur. The present inventors have found that a high-definition image can be stably obtained for a long period of time without impairing the fixability by using a toner using a resin.
[0041]
Furthermore, in the image forming method of the present invention, it was also found that durability and transfer efficiency are further improved by using a toner in which the content of a specific compound (impurity) is controlled.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
The image forming method of the present invention is at least composed of a binder resin, a colorant, and a wax component, and is characterized by using a toner containing a polycarbonate resin as the binder resin.
[0043]
The polycarbonate resin, which is an essential component in the toner used in the image forming method of the present invention, has a repeating unit represented by the following general formula (I) in the molecular structure.
[0044]
[Outside 1]

[Wherein, R represents an organic group. ]
[0045]
The general formula (I) has various structures. For example, any known polycarbonate produced by reacting a dihydric phenol and a carbonate precursor by a solution method or a melt method can be used. In the following general formula (II)
[0046]
[Outside 2]

[In the formula, R² Is a hydrogen atom, an aliphatic hydrocarbon group or an aromatic substituent.² When there are plural groups, they may be the same or different, m is a number from 0 to 4, Z is a single bond, an aliphatic hydrocarbon group, an aromatic substituent,- S-, -SO-, -SO₂ A bond represented by-, -O- or -CO- is shown. ]
The polymer which has a repeating unit of the structure represented by these is mentioned.
[0047]
This polycarbonate resin can be applied to various materials, but is usually represented by the general formulas (III) to (V).
[0048]
[Outside 3]

[In the formula, R² Is a hydrogen atom, an aliphatic hydrocarbon group or an aromatic substituent.² When there are plural groups, they may be the same or different, m is a number from 0 to 4, Z is a single bond, an aliphatic hydrocarbon group, an aromatic substituent,- S-, -SO-, -SO₂ A bond represented by-, -O- or -CO- is shown. ]
It can be easily produced by reacting a dihydric phenol represented by the formula (1) with a carbonate precursor such as phosgene or a carbonate compound.
[0049]
That is, for example, in a solvent such as methylene chloride, in the presence of a known acid acceptor or molecular weight regulator, by reaction of a dihydric phenol with a carbonate precursor such as phosgene, or like a dihydric phenol and diphenyl carbonate. Produced by transesterification with a carbonate precursor.
[0050]
There are various dihydric phenols represented by the above general formulas (III) to (V), such as 2,2-bis (4-hydroxyphenyl) propane (common name: bisphenol A), for example, bis (4 -Hydroxyphenyl) methane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) naphthylmethane, bis (4-hydroxyphenyl)-(4-isopropylphenyl) methane, bis (3,5-dimethyl- 4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1-naphthyl-1,1-bis (4-hydroxyphenyl) ethane, 1-phenyl-1,1-bis (4-hydroxy) Phenyl) ethane, 1,2-bis (4-hydroxyphenyl) ethane, 2-methyl-1,1-bis (4- Droxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1-ethyl-1,1-bis (4-hydroxyphenyl) propane, 2,2-bis (3- Methyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane, 1,4-bis (4-hydroxyphenyl) butane, 2, 2-bis (4-hydroxyphenyl) pentane, 4-methyl-2,2-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy) Phenyl) hexane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxyphenyl) nonane, 1,10 Dihydroxyarylalkanes such as bis (4-hydroxyphenyl) decane and 1,1-bis (4-hydroxyphenyl) cyclodecane; bis (4-hydroxyphenyl) sulfone and bis (3,5-dimethyl-4-hydroxyphenyl) Dihydroxyaryl sulfones such as sulfones; dihydroxyaryl ethers such as bis (4-hydroxyphenyl) ether and bis (3,5-dimethyl-4-hydroxyphenyl) ether; 4,4'-dihydroxybenzophenone and 3,3 ' , 5,5'-tetramethyl-4,4'-dihydroxybenzophenols; bis (4-hydroxyphenyl) sulfides, bis (3-methyl-4-hydroxyphenyl) sulfides and bis (3 5-Dimethyl Dihydroxyaryl sulfides such as (l-4-hydroxyphenyl) sulfide; dihydroxyaryl sulfoxides such as bis (4-hydroxyphenyl) sulfoxide; dihydroxydiphenyls such as 4,4'-dihydroxydiphenyl; hydroquinone, solcinol and methylhydroquinone And dihydroxybenzenes such as 1,5-dihydroxynaphthalene and 2,6-dihydroxynaphthalene. These dihydric phenols may be used alone or in combination of two or more.
[0051]
Examples of the carbonate compound include diaryl carbonates such as diphenyl carbonate; and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate.
[0052]
As the polycarbonate resin used in the present invention, a copolymer or blend using two or more homopolymers using one of these dihydric phenols is used. Furthermore, the thermoplastic random branched polycarbonate resin obtained by making a polyfunctional aromatic compound react with the said dihydric phenol and / or a carbonate precursor may be sufficient.
[0053]
In order to adjust the glass transition temperature and viscoelasticity of the polycarbonate resin, a part of the above dihydric phenol is ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1, 4-butanediol, neopentyl glycol, 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (2-hydroxyethyl) benzene, 1,4-cyclohexanedimethanol, polyethylene glycol, propylene glycol, hydrogenated bisphenol A and its derivatives, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, substituted with polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol Sex polycarbonate resin is also preferably used. In this case, it is possible to simply replace a part of the dihydric phenol and to produce the same by the method described above. However, as another example of the production method, the dihydric phenol and the aliphatic or aromatic bischloroformate are used. And pyridine as a catalyst in a methylene chloride solvent. Of course, synthesis by other production methods is also possible.
[0054]
Furthermore, in the present invention, as the polycarbonate-based resin, the above-described polycarbonate and polystyrene, styrene- (meth) acrylic copolymer, polyester, polyurethane, epoxy resin, polyolefin, polyamide, polysulfone, polycyanoaryl ether, polyarylene sulfide, and the like. Use of block-modified copolymers with monomers to match other polymers and graft-modified copolymers grafted with alkyl (meth) acrylate monomers, (meth) acrylic acid monomers, maleic acid monomers, or styrenic monomers Is possible.
[0055]
In the present invention, the content of the polycarbonate resin in the toner is not particularly limited, but is 0.1 to 50% by weight, preferably 0.2 to 40% by weight, more preferably based on the total weight of the binder resin. It is good that it is 0.3-30 weight%, More preferably, it is 0.5-30 weight%. Normally, toners are designed to prevent low-temperature and high-temperature offsets by designing viscoelasticity of the toner by using a high-molecular-weight resin or a cross-linked resin and a low-molecular-weight resin as a binder resin. However, if the content of the polycarbonate resin in the binder resin exceeds 50% by weight, it becomes difficult to produce a toner having such a design, and it becomes difficult to balance the durability and the fixing property. . When the content of the polycarbonate-based resin in the binder resin is less than 0.1% by weight, it is difficult to obtain excellent durability that is an effect of the present invention.
[0056]
The molecular weight of the polycarbonate resin used as the binder resin for the toner in the image forming method of the present invention is not particularly limited, but the peak molecular weight is 1000 to 500,000 in the molecular weight distribution measured by gel permeation chromatography (GPC) described later. What exists in a molecular weight area | region is preferable, More preferably, it exists in the molecular weight area | region of 2000-100000. Durability such as toner fusion with a peak molecular weight lower than 1000 may be adversely affected. If the molecular weight is higher than 500,000, the durability will be further improved, but the melt viscosity will be too high and the balance with the fixing property will be increased. Is difficult to remove. In producing the polycarbonate resin used in the present invention, an appropriate molecular weight regulator, a branching agent for improving viscoelasticity, a catalyst for promoting the reaction, and the like can be used as necessary.
[0057]
In the binder resin used in the toner for the image forming method of the present invention, as other resins used in combination with the polycarbonate resin, generally used styrene-acrylic resins, styrene-butadiene resins, polyester resins and Epoxy resins are exemplified, and styrene-acrylic resins, polyester resins, and epoxy resins are particularly preferably used. These resins may be produced by any known method. For example, a styrene-acrylic resin can be obtained by polymerizing monomers for forming them. Specifically, styrene monomers such as styrene, o (m-, p-)-methylstyrene, m (p-)-ethylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, ( Meth) propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Preferred are (meth) acrylic acid ester monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, and ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide. Used. These may be used alone or in general so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-p139-192 (John Wiley & Sons) is 40-75 ° C. It is used by appropriately mixing the monomer. When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, whereas when it exceeds 75 ° C., the fixing point of the toner is increased. In particular, in the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is lowered, the color reproducibility is poor, and the transparency of the OHP image is further lowered.
[0058]
In the toner relating to the image forming method of the present invention, the content of a component having a repeating unit of a polycarbonate-based resin contained in a component having a molecular weight of 1000 or less in the molecular weight distribution by GPC of a THF soluble component is the toner. When the content is 15.0% by weight or less based on the above, durability is further improved.
[0059]
Generally, the type of impurities contained in the polycarbonate-based resin varies depending on the type of the polycarbonate-based resin and the manufacturing method, and the polycarbonate-based resin raw material, by-products, by-products, decomposition products thereof, and polymerization catalyst There are various compounds such as polymerization terminators, polymerization solvents and antioxidants. For example, chlorinated aliphatic and aromatic hydrocarbons (eg, dichloromethane), phosgene, phenol, t-butylphenol, organic amines, sodium chloride, aromatic compounds having two or more hydroxyl groups in one molecule ( For example, a dihydric phenol used as a monomer for the polycarbonate resin such as 2,2-bis (3-methyl-4-hydroxyphenyl) propane) and an aliphatic compound having two or more hydroxyl groups in one molecule (For example, a diol used as a monomer of the polycarbonate resin such as 1,4-butanediol), a polycarbonate oligomer, a compound having two or more hydroxyl groups in a molecule, and a polymerization terminator via carbonic acid. Ester-linked compounds (for example, dihydric phenol and p-tertiary butyl phenol are Ester-linked compounds) Mono and / or diformates of aromatic compounds having two or more hydroxyl groups in one molecule (for example, phenylenebischloroformate), aliphatic compounds having two or more hydroxyl groups in one molecule Mono- and / or diformates (eg ethylene bischloroformate), diaryl carbonates (eg diphenyl carbonate), dialkyl carbonates (eg dimethyl carbonate).
[0060]
Of these impurities, low-boiling compounds such as dichloromethane and water-soluble compounds such as sodium chloride can be removed relatively easily in the production process of the polycarbonate-based resin. It often remains in the resin. Among these high-boiling and low-molecular-weight impurities, monomers having two or more hydroxyl groups in one molecule (for example, dihydric phenols) used in the production of the polycarbonate resin and repeating units of the polycarbonate resin A toner containing a large amount of a component having a molecular weight of 1000 or less (a compound in which a polycarbonate oligomer or a compound having two or more hydroxyl groups in one molecule and a polymerization terminator such as a monohydric phenol ester-bonded via carbonic acid). When manufactured, not only the durability (fusing to the developer carrying member, the photosensitive member and the intermediate transfer member), which is an important technical point in the present invention, but also the toner charge amount (image density reduction and fogging) is reduced. Increase), decrease in environmental stability of toner, coloring due to air oxidation of phenolic impurities (discoloration of image), impurity odor during fixing, impure Of OHP permeability due to crystallization of the resin, unexpected crosslinking of the binder resin in the melt-kneading process, which is one of the toner manufacturing processes in the pulverization method, and the polymerization-inhibiting action of phenolic impurities during the production of the polymerization toner Various serious problems occur, causing troubles in long-term use.
[0061]
Compounds that adversely affect the various performances and durability of these toners include not only components having a repeating unit of polycarbonate resin in the structure but a molecular weight of 1000 or less, as well as monomers and derivatives of polycarbonate resin. The content of the monomer and the derivative thereof is proportional to the content of a component having a molecular weight of 1000 or less having a repeating unit of the polycarbonate resin in the structure, and the repeating unit of the polycarbonate resin has a structure. Various investigations by the present inventors have revealed that the above-mentioned problems do not occur if the content of the component having a molecular weight of 1000 or less is 15.0% by weight or less based on the toner. Further, in order to further improve the performance and characteristics of the toner, the content of the component having a repeating unit of polycarbonate resin having a molecular weight of 1000 or less is more preferably 10.0% by weight or less, particularly preferably 5.0. % By weight. Of course, a polycarbonate resin purified by reprecipitation so that a compound having a molecular weight of 1000 or less having a repeating unit of the polycarbonate resin in its structure is not detected at all even if the toner is analyzed in various ways should be used as the binder resin. Is most preferred.
[0062]
When the toner contains more than 15.0% by weight of a component having a repeating unit of polycarbonate resin contained in a component having a molecular weight of 1000 or less in the molecular weight distribution by GPC measurement, the durability of the toner is lowered. However, the storage stability is deteriorated and the change in image density becomes large when a large number of sheets are printed out. In addition, the transfer efficiency may vary due to environmental changes and fog may increase.
[0063]
In the present invention, the qualitative and quantitative analysis of the component having the repeating unit of the polycarbonate resin contained in the component having a molecular weight of 1000 or less in the molecular weight distribution by GPC of the THF soluble part of the toner is carried out by various methods. can do. For example, the toner may have a nuclear magnetic resonance spectrum (¹ H-NMR,¹³Spectral analysis such as C-NMR), infrared absorption spectrum (IR), Raman spectrum, ultraviolet absorption spectrum (UV), mass spectrum (MS), elemental analysis, GPC, gas chromatography (GC), liquid chromatography (HPLC ), Or other chemical analysis. If analysis is difficult with the toner itself, the toner may be Soxhlet extracted with a solvent that dissolves the binder resin, such as tetrahydrofuran and toluene, and the filtrate may be concentrated with an evaporator before the above analysis. Furthermore, various analysis means such as performing the above analysis on a sample obtained by separating components having a molecular weight of 1000 or less by liquid chromatography or GPC, or a sample extracted with a single or mixed solvent can be employed. These analysis means can be used alone or in combination as necessary. Further, a component having a molecular weight of 1000 or less in the toner is fractionated by GPC, and the fractionated component is completely hydrolyzed with, for example, alkali,¹ H-NMR,¹³There is also a method of performing qualitative and quantitative analysis of monomers having two or more hydroxyl groups in one molecule (for example, dihydric phenols) used in the production of the polycarbonate-based resin by analysis means such as C-NMR and IR. is there. Of course, the content of the monomer quantified in this case is a polycarbonate oligomer having a GPC molecular weight of 1000 or less, a compound having two or more hydroxyl groups in one molecule, and a polymerization terminator such as a monohydric phenol esterified via carbonic acid. This is the sum of the monomers generated by hydrolysis of the combined compounds and the residual monomers originally contained in the polycarbonate-based resin (at the time of polymerization). After the qualitative and quantitative determination of the terminator, the value converted to the content of the polycarbonate oligomer and the compound in which the monomer and the polymerization terminator are ester-bonded via carbonic acid is 15.0% by weight based on the toner. As a result, the content of the compound having a GPC molecular weight of 1000 or less having a repeating unit of the polycarbonate resin in the structure is also 15.0% by weight. It is not unlikely to obtain, can be employed as a means of analyzing a toner according to the present invention.
[0064]
The THF soluble content of the toner and the molecular weight distribution of the resin are measured by gel permeation chromatography (GPC). As a specific GPC measurement method, a solution obtained by dissolving a sample of resin or the like in tetrahydrofuran (THF) at room temperature for 24 hours is filtered through a solvent-resistant membrane filter having a pore diameter of 0.2 μm to obtain a sample solution. Measured under the following conditions. In addition, sample preparation adjusts the quantity of THF so that the density | concentration of the component soluble in THF may be 0.4 to 0.6 weight%.
Equipment: High-speed GPC HLC8120 GPC (manufactured by Tosoh Corporation)
Column: Seven series of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK)
Eluent: Tetrahydrofuran
Flow rate: 1.0 ml / min
Oven temperature: 40.0 ° C
Sample injection volume: 0.01ml
[0065]
In calculating the molecular weight of the sample, standard polystyrene resin (TSO standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F- manufactured by Tosoh Corporation) was used. 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500).
[0066]
In the present invention, it is more preferable to use a toner containing a polycarbonate resin on the surface of the toner particles because the durability of the toner can be further improved.
[0067]
Confirmation of the presence of the polycarbonate resin on the surface of the toner particles can be carried out using any analytical means. As an example, first, the tomographic surface of the toner is observed with a TEM to confirm whether the toner surface has a contrast. When polycarbonate-based resin is present on the surface, contrast is given to that portion. Specifically, after sufficiently dispersing toner particles in a room temperature curable epoxy resin and curing for 2 days in an atmosphere of 40 ° C., dyeing is performed, and then a microtome equipped with diamond teeth is formed. A flaky sample is cut out and the tomographic surface of the toner is observed using a transmission electron microscope. In the present invention, a ruthenium tetroxide dyeing method is used to make a contrast between materials by utilizing a slight difference in crystallinity between the wax component to be used and the binder resin constituting the outer shell. It is preferable to use in combination with osmium.
[0068]
Next, by using photoacoustic spectroscopy (PAS = Photoacoustic Spectroscopy) and changing the scan speed of the movable mirror, the composition of the obtained toner particle surface is analyzed by infrared absorption spectrum (IR) / PAS. If the contrast is observed continuously or discontinuously on the toner surface by the TEM observation and the polycarbonate resin is confirmed by IR / PAS analysis, it is judged that the polycarbonate resin is present on the toner surface. it can.
[0069]
In addition to IR / PAS, composition analysis of the toner surface combining Raman spectroscopy and the above PAS, elemental analysis of the toner surface by ESCA (Electron Spectroscopy for Chemical Analysis), energy dispersive X-ray spectrometer and electron beam energy There are various analysis means such as elemental analysis of the toner surface by an electron microscope equipped with an analyzer. These analysis means are used alone or in combination as necessary.
[0070]
When the toner of the present invention is produced by the polymerization method described later, the obtained toner particles have a main peak in the molecular weight region of 5000 to 100,000 in the molecular weight distribution by GPC of the THF-soluble matter, and the weight average molecular weight. It is preferable to have a ratio (Mw / Mn) of 2 to 300 of (Mw) and number average molecular weight (Mn).
[0071]
In the toner according to the present invention, the value of the shape factor SF-1 measured by the image analysis apparatus is 100 to 160, the value of the shape factor SF-2 is preferably 100 to 140, and the shape factor SF-1 More preferably, the value is 100 to 140, and the shape factor SF-2 is 100 to 120. Furthermore, it is particularly preferable if the above conditions are satisfied and the value of (SF-2) / (SF-1) is 1.0 or less.
[0072]
In the present invention, the SF-1 indicating the shape factor is a random sampling of 100 toner images magnified by 500 times using, for example, an FE-SEM (S-800) manufactured by Hitachi, Ltd. For example, an image analysis apparatus (Luzex III) manufactured by Nicole Inc. is introduced through the interface for analysis, and a value calculated from the following equation is defined as a shape factor SF-1.
[0073]
[Outside 4]

[In the formula, MXLNG represents the absolute maximum length of the toner, and AREA represents the projected area of the toner. ]
[0074]
Furthermore, the shape factor SF-2 refers to a value obtained by calculation from the following equation.
[0075]
[Outside 5]

[Where PERI indicates the peripheral length of the toner, and AREA indicates the projected area of the toner. ]
[0076]
The shape factor SF-1 indicates the degree of roundness of the toner, and the shape factor SF-2 indicates the degree of unevenness of the toner particles. By controlling these shape factors, it is possible to improve toner fusing on the photoconductor, toner carrier, and intermediate transfer body when printing a large number of images, further improving the durability of the image forming method of the present invention. Can be made.
[0077]
In the case of 160 <SF-1, the toner moves away from the spherical shape and approaches an indeterminate shape, the toner is easily crushed in the developing unit, the particle size distribution is fluctuated, the charge amount distribution is likely to be broad, and the non-image area on the photoconductor Toner development, so-called fogging, tends to occur. Further, since the contact area of the toner becomes large, the toner easily adheres to the photosensitive member, the toner carrier, and the intermediate transfer member, which is not preferable because it causes toner fusion.
[0078]
In the case of 140 <SF-2, the transfer efficiency of the toner onto the transfer material is reduced and the transfer residual toner increases. Therefore, in the configuration using the intermediate transfer member which is one of the features of the present invention, the cleaning member is strongly This is not preferable because the toner needs to be pressed and toner fusion is promoted.
[0079]
When the value of (SF-2) / (SF-1) exceeds 1.0, the surface of the toner particles is not smooth, and the toner particles have a large number of irregularities. The transfer efficiency tends to decrease during transfer and transfer from the intermediate transfer member to the transfer material, and the toner fusion must be promoted.
[0080]
In particular, the above-described tendency becomes apparent when a full-color image forming apparatus that develops / transfers a plurality of toner images using an intermediate transfer member is used. That is, in the generation of a full-color image, toner images for four colors are formed on the intermediate transfer member and then transferred onto the transfer material at a time, so that the amount of residual toner is inevitably increased.
[0081]
Furthermore, in that case, since the transfer process is carried out substantially twice, the rate of decrease in transfer efficiency causes a significant decrease in toner utilization efficiency and becomes a problem. In digital full-color copying machines and printers, color image originals are color-separated in advance using a B (blue) filter, G (green) filter, and R (red) filter, and then a dot latent image of 20 to 70 μm is formed on the photoreceptor. It is necessary to form and reproduce a multicolor image faithful to the original by using a primary color mixing action using each color toner of Y (yellow) toner, M (magenta) toner, C (cyan) toner, and B (black) toner. There is. At this time, since a large amount of Y toner, M toner, C toner, and B toner is loaded on the photosensitive member or the intermediate transfer member corresponding to the color information of the document or CRT, each color used in the present invention is used. The toner is required to have extremely high transferability, and in order to achieve this, toner particles whose toner shape factors SF-1 and SF-2 satisfy the above conditions are preferable.
[0082]
In the image forming method of the present invention, when a toner having a weight average particle diameter of 2 μm to 10 μm, preferably 2 to 9 μm, more preferably 4 μm to 8 μm is used, a very high quality image can be stably obtained for a long period of time. be able to.
[0083]
In general, it is known that as the particle size of the toner becomes finer, the resolution at the time of development is improved. However, in addition to the increase in the surface area of the entire toner, the fluidity and agitation as the toner powder are reduced. In addition to making it difficult to uniformly charge the particles, the adhesion force to the photosensitive member and the intermediate transfer member is increased, which causes toner fusion.
[0084]
However, by regulating the toner SF-1 and SF-2 as described in the present invention, it becomes possible to uniformly charge individual particles even with a toner having a small particle diameter, By including a polycarbonate resin having a small content of 1000 or less, aggregation between toner particles is suppressed, and a high-definition image can be obtained over a long period of time.
[0085]
The particle size distribution of the toner can be measured by various methods. In the present invention, a Coulter counter was used.
[0086]
For example, a Coulter Counter TA-II type (manufactured by Coulter Co.) is used as a measuring device, an interface (manufactured by Nikkiki Co., Ltd.) for outputting the number distribution and volume distribution and a personal computer are connected. An approximately 1% NaCl aqueous solution is prepared. For example, ISOTON II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 10 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the particle diameter of the toner according to the present invention is determined by using the Coulter counter TA-II type using, for example, a 100 μm aperture.
[0087]
Examples of the wax component used in the toner relating to the image forming method of the present invention include paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fitzscher Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, carnauba wax and derivatives thereof. Higher fatty acids and metal salts thereof, higher aliphatic alcohols, higher aliphatic esters, aliphatic amide waxes, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, and petractams. Derivatives include oxides, block copolymers with vinyl monomers, and graft modified products.
[0088]
Among these wax components, those having a maximum endothermic peak in the region of 40 to 130 ° C., preferably in the region of 40 to 90 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter Is more preferable. By having the maximum endothermic peak in the above temperature range, the mold releasability is effectively expressed while greatly contributing to low-temperature fixing. When the maximum endothermic peak is less than 40 ° C., the self-cohesion force of the wax component becomes weak, and as a result, the high temperature offset resistance deteriorates. On the other hand, when the maximum endothermic peak exceeds 130 ° C., the fixing temperature becomes high and low temperature offset tends to occur, and it becomes difficult to appropriately smooth the fixed image surface. Is not preferable from the viewpoint of color mixing deterioration. Further, in the case where granulation / polymerization is performed in an aqueous medium and a toner is directly obtained by the polymerization method, if the maximum endothermic peak temperature is high, problems such as precipitation of a wax component mainly during granulation are undesirable.
[0089]
The maximum endothermic peak temperature of the wax component is measured according to “ASTM D 3418-8”. For the measurement, for example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. An aluminum pan is used as a measurement sample, an empty pan is set for control, and the temperature is raised from 10 ° C. to 180 ° C. at a heating rate of 10 ° C./min.
[0090]
In the present invention, the amount of these wax components added is particularly preferably in the range of 0.1 to 50% by weight, preferably 0.5 to 30% by weight, based on the total toner. If the content is less than 0.1% by weight, the effect of suppressing the offset is poor, and if it exceeds 50% by weight, the long-term storage stability is deteriorated, the dispersibility of other toner materials is deteriorated, and the image characteristics are deteriorated. Connected.
[0091]
Examples of the colorant used in the toner relating to the image forming method of the present invention include the following yellow colorant, magenta colorant, and cyan colorant. As the black colorant, carbon black, magnetic material, titanium black, or a mixture thereof. Alternatively, a mixture of yellow colorant / magenta colorant / cyan colorant shown below and toned in black is used.
[0092]
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180 are preferably used.
[0093]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.
[0094]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 can be particularly preferably used.
[0095]
These colorants can be used alone or mixed and further used in the form of a solid solution. The colorant is selected from the viewpoints of hue, saturation, lightness, weather resistance, OHP transparency, and dispersibility. The added amount of the colorant is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the adhesive resin in the toner. If it is less than 1 part by weight, sufficient coloring power cannot be obtained, and if it exceeds 20 parts by weight, the transparency of the OHP image is lowered.
[0096]
Further, the toner relating to the image forming method of the present invention uses a magnetic material as a black colorant, and can also be used as a magnetic toner. Magnetic materials that can be used in this case include iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel, or aluminum of these metals, cobalt, copper, lead, magnesium, tin, zinc, Metal alloys such as antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof.
[0097]
These magnetic materials have an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm. The amount of the magnetic substance to be contained in the toner particles is 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight, based on 100 parts by weight of the resin. Further, a magnetic material having a coercive force (Hc) of 20 to 300 oersted, a saturation magnetization (σs) of 50 to 200 emu / g, and a residual magnetization (σr) of 2 to 20 emu / g when 10 K oersted is applied is preferable.
[0098]
As the charge control agent used for the toner relating to the image forming method of the present invention, a known charge control agent can be used, and a charge control agent capable of maintaining a constant charge amount with high charging speed is particularly preferable. Further, when the toner particles are produced using a direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable. Specific compounds include metal compounds of aromatic carboxylic acids such as salicylic acid, naphthoic acid and dicarboxylic acid, metal salts or metal complexes of azo dyes or azo pigments, sulfonic acid or carboxylic acid groups as negative charge control agents. Examples thereof include a polymer compound having a side chain, a boron compound, a urea compound, a silicon compound, and a calixarene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound. The charge control agent is preferably used in an amount of 0.5 to 10 parts by weight with respect to 100 parts by weight of the resin. However, in the present invention, the addition of a charge control agent is not essential, and it is not always necessary to include the charge control agent in the toner particles by actively utilizing frictional charging with the developer regulating (blade) member or the toner carrier. Absent.
[0099]
There are various methods for producing the toner according to the image forming method of the present invention. For example, in the case of producing by a pulverization method, a binder resin containing a polycarbonate resin, a wax component, a colorant and / or a magnetic material is used. Body, charge control agent or other additives are thoroughly mixed by a mixer such as a Henschel mixer or ball mill, melt kneaded using a heat kneader such as a pressure kneader or extruder, and solidified after cooling and solidification. The target is collided with a target or under a jet stream and pulverized to a desired toner particle size. Next, the particle size distribution is sharpened through a classification step. After pulverization or classification, toner particles may be smoothed and spheroidized as necessary. Further, the toner of the present invention can be obtained by sufficiently mixing the classified powder with a fluidizing agent such as fine silica particles and a mixer such as a Henschel mixer. When adopting the above pulverization method, the polycarbonate resin and other resins are dissolved in an organic solvent such as xylene (heating if necessary) and mixed uniformly, and then the binder resin mixture from which the solvent has been removed is used as a raw material. As a result, even if a polycarbonate resin having a high glass transition temperature is used, the dispersion in the toner is good, and this is a particularly preferable production method.
[0100]
Furthermore, as another method for producing the toner, there is a method in which a polycarbonate resin that has been micronized into a classified powder is added and mixed well, and the polycarbonate resin is fixed to the toner surface thermally or mechanically. The binder resin in the powder may contain a polycarbonate resin, or may not contain at all. Further, the toner particles may be smoothed and spheroidized after being fixed.
[0101]
Further, when the toner of the present invention is produced by a polymerization method, a polycarbonate resin is added to the polymerization system, and Japanese Patent Publication No. 36-10231, Japanese Patent Publication No. 59-53856, Japanese Patent Publication No. 59-61842. A method for directly producing a toner by using a suspension polymerization method as described in the publication, and a dispersion polymerization method for directly producing a toner by using an aqueous organic solvent that is soluble in the monomer and insoluble in the obtained polymer. Alternatively, the toner of the present invention can be obtained by an emulsion polymerization method represented by a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polymerization initiator. Also, polymer particles containing no polycarbonate-based resin are produced by a polymerization method, and then a particulate polycarbonate-based resin is adhered to the surface of the polymer particles, and the particles are smoothed and spheroidized as necessary. A method can also be employed. Other methods include, for example, a method of obtaining a spherical toner by atomizing a toner raw material mixture containing a polycarbonate resin into air using a disk or a multi-fluid nozzle described in JP-B-56-13945. .
[0102]
Among the above-described toner production methods, the melt spray method is likely to have a wide particle size distribution of the obtained toner even if the SF-1 value, which is the spherical coefficient of the toner measured with Luzex, can be set to 100 to 160. . On the other hand, the dispersion polymerization method shows a very sharp particle size distribution, but the production equipment is complicated due to the narrow selection of materials used and the use of organic solvents in terms of waste solvent treatment and solvent flammability. It is easy to get complicated. The emulsion polymerization method has an advantage that the particle size distribution of the toner is relatively uniform, but generally the particle size of the generated particles is very fine and it is difficult to use the toner as it is. Furthermore, the terminal of the water-soluble polymerization initiator used and the emulsifier are present on the toner particle surface, which may deteriorate the environmental characteristics.
[0103]
On the other hand, the production method by smoothing and spheroidizing the toner particles and the production method by the polymerization method can easily keep the value of SF-1 in the range of 100 to 160 and the value of SF-2 in the range of 100 to 140. Yes, it can be said to be a preferable production method. Further, the method for producing the toner of the present invention by the polymerization method has an SF-1 value of 100 to 140, an SF-2 value of 100 to 120, and an (SF-2) / (SF-1) value of 1. It is very easy to control to 0.0 or less, and even a polycarbonate resin having a high melting temperature can be used if it is dissolved in the monomer composition to be used. This is a particularly preferable production method.
[0104]
The polycarbonate-based resin contained in the toner of the present invention may be contained in any shape and state in the toner, and is in a phase-separated state even in a state compatible with other binder resins. Also good. For example, when the polycarbonate resin and other binder resin are melt-kneaded by the above-described pulverization method, the polycarbonate-based resin does not necessarily have to be melted in this melt-kneading process. It may be in a dispersed state. In such a case, the polycarbonate resin in the toner is dispersed in the other binder resin used together. When polycarbonate resin and other binder resin are uniformly dissolved and mixed in advance using an organic solvent such as xylene, the problem is that the polycarbonate resin is finely dispersed in other resins or sometimes compatibilized. However, when kneading the polycarbonate resin powder and other binder resin without carrying out such a homogenization operation and kneading below the melting temperature of the polycarbonate resin, the polycarbonate resin Since the powder is dispersed in the toner with a particle size as it is, it is preferable to use a polycarbonate resin finely pulverized to, for example, 1 μm or less, preferably 0.5 μm or less.
[0105]
Furthermore, there is a production method that combines a polymerization method with toner particle smoothing and spheronization, and a method of producing a toner in which polycarbonate resin is continuously or discontinuously present on the surface by the polymerization method. preferable. In this method, it is easy to control the value of SF-1 to 100 to 140, the value of SF-2 to 100 to 120, and the value of (SF-2) / (SF-1) to 1.0 or less. Further, in the tomographic observation of the toner using a transmission electron microscope (TEM), the polycarbonate-based resin is present on the surface continuously or discontinuously, and is obtained from the vinyl-based monomer inside. The binder resin and the wax component are present, and the wax component is dispersed in the binder resin in a substantially spherical and / or spindle-shaped island shape. This is a very preferable production method because it is possible to obtain a toner excellent in heat resistance, low-temperature fixability, blocking resistance and the like.
[0106]
When a polymerization method is used as a toner production method, the particle size distribution control and particle size control of the toner particles can be controlled by changing the type and amount of a poorly water-soluble inorganic salt or a dispersing agent that acts as a protective colloid or mechanically. Predetermined toner particles can be obtained by controlling the apparatus conditions (for example, the circumferential speed of the rotor, the number of passes, the stirring conditions such as the shape of the stirring blades and the container shape) or the solid content concentration in the aqueous solution.
[0107]
When the toner is produced by the direct polymerization method, examples of the polymerization initiator used include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1 ′. -Azo or diazo polymerization initiators such as azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide Peroxide polymerization initiators such as methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used. The amount of the polymerization initiator used varies depending on the desired degree of polymerization, but is generally 0.5 to 20% by weight based on the polymerizable monomer. The kind of the polymerization initiator is slightly different depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature. In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor or the like may be further added.
[0108]
When a suspension polymerization method using a dispersion stabilizer is used as a toner production method, the dispersion stabilizer used is an inorganic compound such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, Examples include magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, hydroxyethyl cellulose, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, carboxymethyl cellulose and its sodium salt and polyacrylic acid and its salt, and starch. These dispersion stabilizers are preferably used in an amount of 0.2 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer.
[0109]
When an inorganic compound is used as the dispersion stabilizer, a commercially available one may be used as it is, but in order to obtain fine particles, fine particles of the inorganic compound may be generated in a dispersion medium. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution may be mixed under restrained stirring.
[0110]
For fine dispersion of these dispersion stabilizers, 0.001 to 0.1 parts by weight of a surfactant may be used in combination. This is for accelerating the action of the dispersion stabilizer, for example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, oleic acid Examples include calcium.
[0111]
In the case where the direct polymerization method is used as a toner manufacturing method according to the image forming method of the present invention, the following manufacturing method is possible.
[0112]
Add the wax component, colorant, charge control agent, polymerization initiator and other additives to the polymerizable monomer, and disperse the monomer composition that has been uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc. It is dispersed in an aqueous phase containing a stabilizer by a normal stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and stirring time so that the droplets of the monomer composition have the desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization is preferably carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction. Further, in the image forming method of the present invention, for the purpose of improving durability, the latter half of the reaction for removing unreacted polymerizable monomers, by-products, etc. Alternatively, after completion of the reaction, a part of the aqueous medium may be distilled off from the reaction system. After completion of the reaction, the produced toner particles are washed, collected by filtration, and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.
[0113]
The toner relating to the image forming method of the present invention must contain a polycarbonate resin in the binder resin, and as described above, 0.1 to 50% by weight of the binder resin is the polycarbonate resin. Preferably, however, the qualitative and quantitative analysis of the polycarbonate resin can be carried out in various ways. For example, the toner may have a magnetic resonance spectrum (¹H-NMR,¹³Analysis may be performed by various methods such as spectrum analysis such as C-NMR), infrared absorption spectrum (IR), Raman spectrum, ultraviolet absorption spectrum (UV), and mass spectrum (MS), elemental analysis, and other chemical analysis. If the analysis is difficult with the toner itself, the toner may be Soxhlet extracted with a solvent that dissolves the binder resin, such as tetrahydrofuran or toluene, and the filtrate may be concentrated with an evaporator before the above analysis is performed. Furthermore, various analysis means such as performing the above-described analysis on a sample separated by GPC, or a sample separated and extracted with a single or mixed solvent can be employed. These analysis means can be used alone or in combination as necessary.
[0114]
The developer of the present invention may further be used by adding a fluidity improver. The fluidity improver is not particularly limited as long as it can improve the fluidity after the addition to the toner particles. For example, silica fine powder, titanium oxide fine powder, alumina fine powder, and those whose surfaces have been subjected to a hydrophobic treatment can be used alone or in combination of two or more.
[0115]
In the image forming method of the present invention, various charging methods are used. Of course, a contact charging method in which the charging member is brought into contact with the photosensitive member is also preferably used. In this case, when a general toner is used, if the residual toner after cleaning adheres to the direct charging member, which is a subsequent process, charging failure occurs and charging unevenness occurs on the image. Accordingly, it is necessary to make the amount of residual toner smaller and difficult to adhere as compared with corona discharge or the like in which the charging unit does not contact the photoconductor. Therefore, in the direct charging method, it is necessary to use toner that strictly defines SF-1, SF-2, (SF-2) / (SF-1).
[0116]
The conditions for the development step in the image forming method of the present invention are at least the toner layer carried on the toner carrier and the surface of the photosensitive member are in contact, and preferably the toner layer is removed from the surface of the toner carrier. In this state, the surface of the toner carrying member is preferably in contact with the surface of the photosensitive member, and more preferably, a reversal development method is used. Furthermore, the cleaning device such as a cleaning blade is not separately provided, and the developing device itself uses a cleaner-less process for collecting the transfer residual toner on the photoconductor, whereby the size of the device can be greatly reduced. At this time, at the time of development or at the time of blanking before and after development, a bias of a direct current or alternating current component is applied to perform development, and at the same time, the potential is controlled so that the transfer residual toner on the photosensitive member can be collected. At this time, the direct current component is located between the light portion potential and the dark portion potential.
[0117]
As the toner carrying member, an elastic roller is used, and a method of coating the toner on the surface of the elastic roller and bringing it into contact with the surface of the photoreceptor is also used. In this case, due to the electric field acting between the photosensitive member and the elastic roller facing the surface of the photosensitive member via the toner, the transfer residual toner is also cleaned in the cleaning process in the developing process. Therefore, it is necessary to have an electric field in a narrow gap between the photoreceptor surface and the toner carrying surface. For this reason, it is possible to use a method in which the elastic rubber of the elastic roller is resistance controlled to the middle resistance region to keep the electric field while preventing conduction with the surface of the photoreceptor, or a method of providing a thin insulating layer on the surface layer of the conductive roller. . Furthermore, a conductive resin sleeve in which the side facing the surface of the photoreceptor is covered with an insulating material on the conductive roller, or a conductive layer is provided on the side not facing the photoreceptor with the insulating sleeve is also possible. Further, a configuration in which a rigid roller is used as the toner carrying member and the photosensitive member is flexible such as a belt is possible. The resistance of the developing roller as the toner carrier is 10² -10⁹ A range of Ω · cm is preferred.
[0118]
As the surface shape of the toner carrier, when the surface roughness Ra (μm) is set to 0.2 to 3.0, both high image quality and high durability can be achieved. The surface roughness Ra correlates with the toner conveying ability and the toner charging ability. If the surface roughness Ra of the toner carrier exceeds 3.0, it is difficult not only to make the toner layer on the toner carrier thin, but also the chargeability of the toner is not improved, so that improvement in image quality cannot be expected. . By controlling the toner carrying capacity on the surface of the toner carrier by adjusting to 3.0 or less, the toner layer on the toner carrier is thinned, and the number of contact between the toner carrier and the toner increases. Since the chargeability of the toner is also improved, the image quality is synergistically improved. On the other hand, when the surface roughness Ra is smaller than 0.2, it becomes difficult to control the toner coat amount.
[0119]
In the present invention, the surface roughness Ra of the toner carrier is measured using a surface roughness measuring device (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness “JISB0601”. Corresponds to the centerline average roughness. Specifically, a 2.5 mm portion as the measurement length a is extracted from the roughness curve in the direction of the center line, the center line of this extraction portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve is When expressed by y = f (x), it means a value obtained by the following formula expressed in micrometers (μm).
[0120]
[Outside 6]

[0121]
In the image forming method of the present invention, the toner carrier may be rotated in the same direction as the circumferential speed of the photosensitive member, or may be rotated in the opposite direction. When the rotation is in the same direction, it is preferable to set the peripheral speed of the toner carrier to be 1.05 to 3.0 times the peripheral speed of the photosensitive member.
[0122]
When the peripheral speed of the toner carrier is less than 1.05 times the peripheral speed of the photosensitive member, the stirring effect received by the toner layer becomes insufficient, and good image quality cannot be expected. In addition, when developing an image that requires a large amount of toner over a wide area, such as a solid black image, the amount of toner supplied to the electrostatic latent image is insufficient and the image density becomes low. The higher the peripheral speed ratio, the more toner is supplied to the development site, the more frequently the toner is desorbed from the latent image, and the unnecessary parts are scraped off and applied to the necessary parts. Thus, an image faithful to the latent image can be obtained. From the standpoint of development and cleaning, when there is residual toner that is in close contact with the photoconductor, it can be expected that the surface of the photoconductor and the portion where the toner is attached are physically peeled off due to the difference in peripheral speed and recovered by an electric field. The higher the peripheral speed ratio, the more convenient it is for collecting the residual toner. However, when the peripheral speed ratio exceeds 3.0, on the other hand, in addition to various problems caused by excessive charging of the toner as described above, the toner is deteriorated due to mechanical stress and the toner is fixed to the toner carrier. Is generated and promoted, which is not preferable.
[0123]
As the photoreceptor, a-Se, Cds, ZnO₂ A photosensitive drum or photosensitive belt having a photoconductive insulating material layer such as OPC and a-Si is preferably used.
[0124]
As the binder resin of the organic photosensitive layer in the OPC photoreceptor, polycarbonate resin, polyester resin, and acrylic resin are particularly good in transferability and cleaning properties, poor cleaning, toner fusion to the photoreceptor, and external additives. Filming hardly occurs, which is preferable.
[0125]
Next, the image forming method of the present invention will be described below with reference to the accompanying drawings.
[0126]
First, a monochromatic image forming method using the cleanerless process will be described with reference to FIG.
[0127]
In FIG. 1, 100 is a developing device, 109 is a photosensitive member, 105 is a recording material such as paper, 106 is a transfer member, 107 is a fixing pressure roller, 108 is a fixing heating roller, and 110 is in contact with the photosensitive member 109. 1 shows a primary charging member that performs direct charging.
[0128]
A bias power source 115 is connected to the primary charging member 110 so as to uniformly charge the surface of the photoconductor 109.
[0129]
The developing device 100 contains toner 104 and includes a toner carrier 102 that contacts the photoconductor 109 and rotates in the direction of the arrow. Further, a developing blade 101 for regulating the amount of toner and charging, and a coating roller 103 that rotates in the direction of the arrow in order to attach the toner 104 to the toner carrier 102 and to charge the toner by friction with the toner carrier 102. It also has. A developing bias power source 117 is connected to the toner carrier 102. A bias power supply 118 is also connected to the application roller 103, and a voltage is set on the negative side of the developing bias when negatively charged toner is used, and on the positive side of the developing bias when positively charged toner is used. Is done.
[0130]
A transfer bias power supply 116 having a polarity opposite to that of the photoconductor 109 is connected to the transfer member 106. Here, the length in the rotation direction at the contact portion between the photoconductor 109 and the toner carrier 102, that is, a so-called development nip width of 0.2 mm or more and 8.0 mm or less is preferable. If the thickness is less than 0.2 mm, the development amount is insufficient and a satisfactory image density cannot be obtained, and the transfer residual toner is not sufficiently collected. If it exceeds 8.0 mm, the amount of toner supplied becomes excessive, fogging is likely to occur, and the wear of the photosensitive member is also adversely affected.
[0131]
As the toner carrier, a so-called elastic roller having an elastic layer on its surface is preferably used. The hardness of the material of the elastic layer used is preferably 20 to 65 degrees (JISA). The resistance of the toner carrier is 10 in terms of volume resistance.² -10⁹ A range of about Ωcm is preferable. 10² If it is lower than Ωcm, for example, if there is a pinhole on the surface of the photoconductor 109, an overcurrent may flow. Conversely, 10⁹ When it is higher than Ωcm, the toner is likely to be charged up by frictional charging, and the image density is likely to be lowered.
[0132]
The toner coat amount on the toner carrier is 0.1 mg / cm² 1.5 mg / cm or more² The following is preferred. 0.1 mg / cm² If it is less than 1, it is difficult to obtain a sufficient image density, and 1.5 mg / cm² If it exceeds the upper limit, it becomes difficult to uniformly triboelectrically charge all of the individual toner particles, which causes deterioration of fog suppression. Furthermore, 0.2 mg / cm² 0.9 mg / cm² The following is more preferable.
[0133]
The toner coating amount is controlled by the developing blade 101, and the developing blade 101 is in contact with the toner carrier 102 through the toner layer. The contact pressure at this time is preferably in the range of 5 g / cm to 50 g / cm. If the contact pressure is less than 5 g / cm, in addition to controlling the toner coat amount, uniform triboelectric charging becomes difficult, causing fogging. When the contact pressure exceeds 50 g / cm, the toner particles are subjected to an excessive load, so that the deformation of the particles and the fusion of the toner to the developing blade or the toner carrier are likely to occur.
[0134]
As the toner coating amount regulating member, a metal blade, a roller, or the like may be used in addition to the elastic blade for press-contacting the toner.
[0135]
It is preferable to select a frictional charging material suitable for charging the toner to a desired polarity for the elastic regulating member, such as a rubber elastic body such as silicone rubber, urethane rubber or NBR, or a synthetic resin elastic material such as polyethylene terephthalate. Bodies, metal elastic bodies such as stainless steel, copper, phosphor bronze, and composites thereof.
[0136]
Further, when durability is required for the elastic regulating member and the toner carrying member, it is preferable that the metal elastic member is bonded or coated with a resin or rubber so as to contact the sleeve contact portion.
[0137]
Furthermore, an organic substance or an inorganic substance may be added to the elastic regulating member, and it may be melt-mixed or dispersed. For example, the chargeability of the toner can be controlled by adding a metal oxide, metal powder, ceramics, carbon allotrope, whisker, inorganic fiber, dye, pigment, or surfactant. In particular, when the elastic body is a molded body of rubber or resin, fine metal oxide powders such as silica, alumina, titania, tin oxide, zirconia oxide, and zinc oxide, carbon black, charge control materials generally used for toners, etc. It is also preferable to contain.
[0138]
Furthermore, by applying a DC electric field and / or an AC electric field to the regulating member, the uniform thin layer coating property and the uniform charging property are further improved due to the unraveling action on the toner. An image can be obtained.
[0139]
In FIG. 1, a primary charging member 110 uniformly charges a photoconductor 109 that rotates in the direction of an arrow. The primary charging member used here is a charging roller having a basic configuration of a central cored bar 110b and a conductive elastic layer 110a formed on the outer periphery thereof. The charging roller 110 is brought into contact with the entire surface of the electrostatic latent image carrier with a pressing force, and is rotated following the rotation of the electrostatic latent image carrier 1.
[0140]
As a preferable process condition when using the charging roller, the contact pressure of the roller is 5 to 500 g / cm, and the applied voltage is a charging bias of a DC voltage alone or a charging bias in which an AC voltage is superimposed on a DC voltage. It is done. Although not particularly limited, in the present invention, a charging bias of only a DC voltage is preferably used, and a voltage value in this case is used in a range of ± 0.2 to ± 5 kV.
[0141]
Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means have an effect that a high voltage is unnecessary and generation of ozone is reduced as compared with non-contact corona charging. The material of the charging roller and charging blade as the contact charging means is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable film, nylon resin, PVDF (polyvinylidene fluoride) or PVDC (polyvinylidene chloride) can be applied.
[0142]
Following the primary charging step, an electrostatic latent image corresponding to the information signal is formed on the photoconductor 109 by exposure 111 from the light emitting element, and the electrostatic latent image can be developed with toner in an area in contact with the toner carrier 102. Visualize. Furthermore, in the image forming method of the present invention, particularly in combination with a developing system in which a digital latent image is formed on a photoreceptor, it becomes possible to develop the dot latent image faithfully without disturbing the latent image. . Next, the visible image is transferred onto the non-transfer body 105 by the transfer member 106, and the transfer toner 112 is fixed by passing between the heating roller 108 and the pressure roller 107 together with the transfer target body 105. Get. In addition to the heat roller system, the heating and pressure fixing means includes a heating roller having a built-in heating element such as a halogen heater and an elastic pressure roller pressed against the heating roller with a pressing force. A system in which heat is fixed by a heater through a film is also used.
[0143]
On the other hand, the untransferred toner 113 that remains on the photosensitive member 109 without being transferred passes between the photosensitive member 109 and the primary charging member 110 and reaches the developing nip again, and is developed by the toner carrying member 102 by the developing device 100. Collected in.
[0144]
Next, a full color image forming method using a contact developing method using an intermediate transfer member will be described.
[0145]
In the apparatus system shown in FIG. 2, a developer having cyan toner, a developer having magenta toner, a developer having yellow toner, and black are respectively added to the developing devices 24-1, 24-2, 24-3, and 24-4. A developer having toner is introduced, and the electrostatic latent image formed on the photoconductor 1 is developed by the above-described development method or the like, and each color toner image is formed on the photoconductor 21.
[0146]
As the developing means, development can be performed using, for example, a one-component contact developing type developing means having a developing device 31 as shown in FIG. Specifically, the toner 34 supplied from the application roller 32 and whose coating amount is regulated by the developing blade 33 is in contact with the photoconductor 35 while applying a direct current or an alternating electric field to the toner carrier 37 by the power source 36. Develop in the state. In the case of using an alternating electric field, a triangular wave, a rectangular wave, a sine wave, a waveform in which the duty ratio is changed, or a waveform in which the alternating is periodically turned off can be selected and used. A direct current electric field with a small static load is preferably used, and the applied voltage is set to an appropriate value between the dark potential (potential immediately after the charging step) and the bright potential (potential after the exposure step) on the photoreceptor.
[0147]
In any configuration, it is more preferable to set the peripheral speed of the toner carrier to be 1.05 to 3.0 times the peripheral speed of the photosensitive member.
[0148]
The toner image on the electrostatic latent image bearing member is primarily transferred to the intermediate transfer member 25 to which a voltage (for example, ± 0.1 to ± 5 kV) is applied, and the residual toner is transferred by a cleaning unit 28 in contact with the photosensitive member. To be cleaned. The surface of the intermediate transfer member is cleaned by a cleaning unit 29 having a cleaning blade. When there is a toner image on the intermediate transfer member, the cleaning means 29 is separated from the surface of the intermediate transfer member so as not to disturb the toner image.
[0149]
The intermediate transfer member 25 includes a pipe-shaped conductive metal core 25b and an intermediate resistance elastic layer 25a formed on the outer peripheral surface thereof. The cored bar 25b may be a plastic pipe with conductive plating.
[0150]
The medium resistance elastic layer 25a is made of an elastic material such as silicone rubber, Teflon rubber, chloroprene rubber, urethane rubber, EPDM (ethylene propylene diene terpolymer), carbon black, zinc oxide, tin oxide, silicon carbide. The electrical conductivity value (volume resistivity) is 10 by mixing and dispersing a conductivity imparting agent such as^Five -10¹¹Solid or foamed layer adjusted to medium resistance of Ω · cm.
[0151]
The intermediate transfer member 25 is disposed in parallel with the electrostatic latent image carrier 21 and is in contact with the lower surface portion of the electrostatic latent image carrier 21, and is the same as the electrostatic latent image carrier 21. Rotates counterclockwise at the peripheral speed.
[0152]
The first color toner image formed and supported on the surface of the electrostatic latent image carrier 21 passes through the transfer nip where the electrostatic latent image carrier 21 and the intermediate transfer member 25 are in contact with each other. Intermediate transfer is sequentially performed on the outer surface. After the transfer of the toner image onto the recording material, the surface of the intermediate transfer body 25 is cleaned by a removable cleaning means 29.
[0153]
A transfer unit 27 is disposed in parallel with the intermediate transfer member 25 and brought into contact with the lower surface of the intermediate transfer member 25. The transfer unit 27 is, for example, a transfer roller or a transfer belt, and is the same as the intermediate transfer member 25. It rotates in the clockwise direction of the arrow at the peripheral speed. The transfer unit 27 may be disposed so as to be in direct contact with the intermediate transfer member 25, or may be disposed so that the belt is in contact between the intermediate transfer member 25 and the transfer unit 27.
[0154]
In the case of a transfer roller, the basic configuration is a central core metal 27b and a conductive elastic layer 27a that forms the outer periphery thereof.
[0155]
Common materials can be used for the intermediate transfer member and the transfer roller. By setting the volume resistivity value of the elastic layer of the intermediate transfer member to a smaller value, the voltage applied to the transfer roller can be reduced, a good toner image can be formed on the transfer material, and the transfer material can be wrapped around the intermediate transfer member. Can be prevented. In particular, the volume specific resistance value of the elastic layer of the intermediate transfer member is particularly preferably 10 times or more than the volume specific resistance value of the elastic layer of the transfer roller.
[0156]
For example, the conductive elastic layer 27b of the transfer roller 27 has a volume resistance 10 such as polyurethane in which a conductive material such as carbon is dispersed and ethylene-propylene-diene terpolymer (EPDM).⁶ -10^TenIt is made of an elastic body of about Ω · cm. A bias is applied to the cored bar 7a by a low voltage power source. The bias condition is preferably ± 0.2 to 10 kV.
[0157]
When using the contact development method described above and performing development and cleaning, when using the contact charging method in which the charging member is brought into contact with the photosensitive member as a charging means for primary charging of the photosensitive member, a general toner is used. In this case, if the residual toner after cleaning adheres to the contact charging member, which is a subsequent process, charging failure occurs and charging unevenness occurs on the image. Therefore, it is necessary to reduce the amount of toner remaining after transfer as compared with corona discharge or the like in which the charging unit does not contact the photoreceptor. Therefore, in the direct charging method, it is preferable to use toner in which SF-1, SF-2, (SF-2) / (SF-1) is strictly defined in the above-described range.
[0158]
The toner according to the present invention has a high transfer efficiency in the transfer process by controlling the surface shape of the toner particles and a small amount of transfer residue, and therefore has excellent cleaning properties when developing and cleaning in the developing device. In addition, since it contains a tough polycarbonate resin, filming is unlikely to occur on the contact charging member, the photosensitive drum, and the intermediate transfer member. Further, even when a multi-sheet durability test is performed, the toner of the present invention has less embedding of the external additive on the surface of the toner particles than when the conventional toner is used, so that good image quality can be maintained over a long period of time. obtain.
[0159]
Next, the toner image on the transfer material 26 is fixed by a heat and pressure fixing means to obtain a permanent image.
[0160]
【Example】
Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited thereto.
[0161]
Example of resin (1) production
200 parts by weight of xylene was placed in the reaction vessel and the temperature was raised to the reflux temperature. A solution mixture of 85 parts by weight of styrene, 15 parts by weight of acrylate-n-butyl and 2 parts by weight of di-tert-butyl peroxide was added dropwise thereto, and then the solution polymerization was completed in 7 hours under reflux of xylene. A molecular weight resin solution was obtained.
[0162]
On the other hand, 70 parts by weight of styrene, 25 parts by weight of butyl acrylate, 5 parts by weight of monobutyl maleate, 0.2 parts by weight of polyvinyl alcohol, 200 parts by weight of degassed water, and 0.1 parts by weight of benzoyl peroxide were mixed, suspended and dispersed. It was. The suspension dispersion was heated and maintained at 85 ° C. for 24 hours under a nitrogen atmosphere to complete the polymerization, thereby obtaining a high molecular weight resin.
[0163]
30 parts by weight of the high molecular weight resin is put into the solution at the end of the solution polymerization containing 70 parts by weight of the low molecular weight resin, completely dissolved in a solvent and mixed, and then the solvent is distilled off to remove the resin. (1) was obtained.
[0164]
When the obtained resin (1) was analyzed, in the molecular weight distribution by GPC, the low molecular weight side peak molecular weight was 10,000, the high molecular weight side peak molecular weight was 750,000, the weight average molecular weight (Mw) was 360,000, and the number average molecular weight (Mn) was 6000, Mw / Mn was 60, and the glass transition temperature (Tg) was 60 ° C.
[0165]
[Example of toner production]
Toner production example 1
・ Resin (1) 100 parts by weight
・ 1,1-bis (4-hydroxyphenylcyclohexane polycarbonate (peak molecular weight: 5000, Mw: 6000, Mn: 2500) 10 parts by weight
・ Carbon black (colorant) 5 parts by weight
・ Negative charge control agent (compound of monoazo dye and iron) 2 parts by weight
・ Low molecular weight polyethylene (DSC peak 107 ° C) 5 parts by weight
[0166]
The above materials were mixed in advance and melt kneaded at 130 ° C. with a twin screw extruder. This melt-kneaded product was roughly crushed with a hammer mill to obtain a 1 mm mesh pass toner crushed product. Further, the coarsely pulverized product was finely pulverized by a collision type pulverizer using a jet stream and then classified by wind to obtain black powder (toner particles) (1) having a weight average particle size of 9.3 μm. The specific surface area by the BET method is 200 m with respect to 100 parts by weight of the obtained toner particles (1).² The specific surface area is 120 m by hydrophobizing the surface of the silica matrix with a silane coupling agent and silicone oil.² 1.0 part by weight of hydrophobic silica having a weight of / g was externally added to obtain a pulverized toner (1). The obtained toner particles and various physical properties of the toner are shown in Table 1.
[0167]
As shown in Table 1, the toner (1) was obtained by fractionating a component having a molecular weight of 1000 or less by GPC in the molecular weight distribution by GPC of THF-soluble matter.¹ H-NMR,¹³Analysis by C-NMR and IR revealed that the content of a component having a repeating unit of a polycarbonate resin contained in a component having a molecular weight of 1000 or less in the structure was 1.0 on the basis of the weight of the toner. % By weight.
[0168]
The 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate used for the production of the toner (1) is purified by repeating reprecipitation using dichloromethane and isopropanol so as to reduce low molecular weight components and impurities.
[0169]
Further, when the tomographic surface of this toner was observed with a TEM, it was observed that an incompatible island-like dispersion of polycarbonate resin and low molecular weight polyethylene was dispersed throughout the toner.
[0170]
Toner Production Example 2
Toner particles (1) obtained in Toner Production Example 1 are added to an aqueous solution containing a surfactant, surface-treated at 85 ° C. for 2 hours with high-speed stirring, filtered, washed with water, and dried. Thus, black powder (toner particles) (2) having a weight average diameter of about 9.6 μm was obtained. 1.0 part by weight of hydrophobic silica used in Production Example 1 for polymerized toner was externally added to 100 parts by weight of the toner particles (2) to obtain a spheroidized toner (2). The obtained toner particles and various physical properties of the toner are shown in Table 1.
[0171]
Toner Production Example 3
Toner particles (3) and spheroidized toner (3) were obtained in the same manner as in Toner Production Example 2 without using low molecular weight polyethylene. Table 1 shows the toner particles and various physical properties of the toner.
[0172]
Toner Production Example 4
Toner particles (4) and spheroidized toner (4) were obtained in the same manner as in Toner Production Example 2 except that the polycarbonate resin (1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate) was not used. Table 1 shows the toner particles and various physical properties of the toner.
[0173]
Toner Production Example 5
Toner particles (5) and spheroidized toner (5) are obtained in the same manner as in Toner Production Example 2, except that 45 parts by weight of polycarbonate resin (1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate) is used. It was. Table 1 shows the toner particles and various physical properties of the toner.
[0174]
Toner Production Example 6
Toner particles (6) and spheroidized toners (spheroid toners) were prepared in the same manner as in Toner Production Example 2 except that 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate having a peak molecular weight of 3500, Mw of 4000 and Mn of 1800 was used. 6) was obtained.
[0175]
The 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate used for the production of the toner (6) is purified by repeating reprecipitation using dichloromethane and isopropanol so that low molecular weight components and impurities are reduced. .
[0176]
Table 1 shows the toner particles and various physical properties of the toner.
[0177]
Toner Production Example 7
Using the styrene-butadiene copolymer (Mw: 163000, Mn: 18300, Mw / Mn: 8.9) instead of the resin (1), a black classified powder was obtained in the same manner as in Toner Production Example 1. . The obtained black classified powder is added to an aqueous solution containing a surfactant, surface-treated at 90 ° C. for 2 hours while stirring at a high speed, filtered, washed with water, and dried to obtain a weight average diameter of about 10. 5 μm toner particles (7) were obtained. To 100 parts by weight of the toner particles (7), 1.0 part by weight of hydrophobic silica used in Toner Production Example 1 was externally added to obtain a spheroidized toner (7). The obtained toner particles and various physical properties of the toner are shown in Table 1.
[0178]
Toner Production Example 8
・ Resin (1) 100 parts by weight
・ Carbon black (colorant) 5 parts by weight
・ Negative charge control agent (compound of monoazo dye and iron) 2 parts by weight
・ Low molecular weight polyethylene (DSC peak 107 ° C) 5 parts by weight
[0179]
A black powder was obtained using the above raw materials in the same manner as in Toner Production Example 2. 100 parts by weight of the obtained black powder and 10 parts by weight of finely powdered 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate were dry-mixed with a Henschel mixer, and then surface modification was performed using a hybridizer manufactured by Nara Machinery Co., Ltd. Then, toner particles (8) were obtained, and this was designated as spherical toner (8).
[0180]
The 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate used for the production of the toner (8) is purified by repeating reprecipitation using dichloromethane and isopropanol so that low molecular weight components and impurities are reduced. .
[0181]
When the tomographic surface of this toner was observed with a TEM, a layer believed to be composed of a polycarbonate resin was observed on the surface, and an incompatible island-like dispersion believed to be low molecular weight polyethylene was dispersed inside the toner. It was done. The obtained toner particles and various physical properties of the toner are shown in Table 1.
[0182]
Toner Production Example 9
・ Resin (1) 50 parts by weight
・ 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate (peak molecular weight: 3000, Mw: 3500, Mn: 1000) 50 parts by weight
・ Carbon black (colorant) 5 parts by weight
・ Negative charge control agent (compound of monoazo dye and iron) 2 parts by weight
・ Low molecular weight polyethylene (DSC peak 107 ° C) 5 parts by weight
[0183]
The above materials were mixed in advance and melt kneaded at 130 ° C. with a twin screw extruder. This melt-kneaded product was roughly crushed with a hammer mill to obtain a 1 mm mesh pass toner crushed product. Further, the coarsely pulverized product was finely pulverized by a collision-type pulverizer using a jet stream and then classified by air to obtain black powder (toner particles) (9) having a weight average particle size of 9.3 μm. The specific surface area by the BET method is 200 m with respect to 100 parts by weight of the obtained toner particles (9).² The specific surface area is 120 m by hydrophobizing the surface of the silica matrix with a silane coupling agent and silicone oil.² 1.0 part by weight of hydrophobic silica / g was added externally to obtain a pulverized toner (9).
[0184]
The 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate used for the production of the toner particles (9) has not been purified by reprecipitation.
[0185]
Table 1 shows the toner particles and various physical properties of the toner.
[0186]
Toner Production Example 10
To 710 g of ion-exchanged water in a two-liter four-necked flask, 0.1 M Na_Three PO_Four 560 g of an aqueous solution was added and heated to 60 ° C., and then stirred at 12000 rpm using a high-speed stirring device TK type homomixer (manufactured by Tokushu Kika Kogyo). To this, 1.0M-CaCl₂ 85 g of an aqueous solution was gradually added to obtain an aqueous dispersion medium containing a minute hardly water-soluble dispersion stabilizer.
[0187]
On the other hand, as dispersoid
・ 80 parts by weight of styrene
・ 20 parts by weight of n-butyl acrylate
・ Carbon black (colorant) 5 parts by weight
・ 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate (peak molecular weight: 5000, Mw: 6000, Mn: 2600) 5 parts by weight
・ Carbon black 5 parts by weight
・ Negative charge control agent (compound of monoazo dye and iron) 2 parts by weight
・ Ester wax (DSC peak 70 ° C) 5 parts by weight
[0188]
Of the above formulations, only a colorant, an Fe compound of a monoazo dye, and styrene were used to produce a carbon black masterbatch using an attritor (Mitsui Metals). Next, the masterbatch and the remaining material of the above recipe were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Further, while maintaining at 60 ° C., 10 g of initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.
[0189]
The monomer composition was charged into an aqueous dispersion medium prepared in a 2 liter flask of the homomixer. Using a TK homomixer at 60 ° C. in a nitrogen atmosphere, the mixture was stirred at 10,000 rpm for 20 minutes to granulate the monomer composition. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 10 hours.
[0190]
After completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added and Ca is added._Three (PO_Four )₂ Was dissolved, filtered, washed with water, and dried to obtain black suspension particles (toner particles) (10) having a weight average diameter of about 7.1 μm.
[0191]
To 100 parts by weight of the obtained toner particles (10), 1.5 parts by weight of hydrophobic silica used in Toner Production Example 1 was externally added to obtain a polymerized toner (10).
[0192]
The 1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate used for the production of the toner (10) is purified by repeating reprecipitation using dichloromethane and isopropanol so that low molecular weight components and impurities are reduced. .
[0193]
When the tomographic surface of the toner was observed with a TEM, a layer made of polycarbonate resin was observed on the surface, and a spherical dispersion made of low molecular weight polyethylene was observed dispersed inside the toner.
[0194]
Various physical properties of the obtained toner particles and polymerized toner are shown in Table 1.
[0195]
Toner Production Example 11
Toner particles (11) and polymerized toner (11) were obtained in the same manner as in Toner Production Example 10 except that 50 parts by weight of ester wax was used.
[0196]
Various physical properties of the obtained toner particles and polymerized toner are shown in Table 1.
[0197]
Toner Production Example 12
Toner particles (12) and polymerized toner (12) were obtained in the same manner as in Toner Production Example 10 except that the polycarbonate resin (1,1-bis (4-hydroxyphenyl) cyclohexane polycarbonate) was not used.
[0198]
Various physical properties of the obtained toner particles and polymerized toner are shown in Table 1.
[0199]
Toner Production Example 13
To 710 g of ion-exchanged water in a two-liter four-necked flask, 0.1 M Na_Three PO_Four 560 g of an aqueous solution was added and heated to 60 ° C., and then stirred at 12000 rpm using a high-speed stirring device TK type homomixer (manufactured by Tokushu Kika Kogyo). To this, 1.0M-CaCl₂ 85 g of an aqueous solution was gradually added to obtain an aqueous dispersion medium containing a minute hardly water-soluble dispersion stabilizer.
[0200]
On the other hand, as dispersoid
・ 80 parts by weight of styrene
・ 20 parts by weight of n-butyl acrylate
-Bisphenol A-biphenol-hexamethylene glycol copolymer polycarbonate (peak: molecular weight 30000, Mw: 42000, Mn: 16000) 5 parts by weight
・ C. I. Pigment Blue 15: 3 (colorant) 5 parts by weight
Charge control agent (2,5-di-tert-butylsalicylic acid Al compound) 2 parts by weight
Ester wax (DSC peak 70 ° C.) 5 parts by weight
[0201]
Of the above formulations, only a colorant, an Al compound of di-t'ert-butylsalicylic acid, and styrene were premixed using Ebara Milder (manufactured by Ebara Seisakusho). Next, all the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Further, while maintaining at 60 ° C., 10 g of initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.
[0202]
The monomer composition was charged into an aqueous dispersion medium prepared in a 2 liter flask of the homomixer. Using a TK homomixer at 60 ° C. in a nitrogen atmosphere, the mixture was stirred at 10,000 rpm for 20 minutes to granulate the monomer composition. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 10 hours.
[0203]
After completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added and Ca is added._Three (PO_Four )₂ Was dissolved, filtered, washed with water, and dried to obtain colored suspended particles (toner particles) (13) having a weight average diameter of about 6.9 μm.
[0204]
To 100 parts by weight of the obtained toner particles (13), 1.5 parts by weight of hydrophobic silica used in Toner Production Example 1 was externally added to obtain a polymerized toner (13).
[0205]
The bisphenol A-biphenol-hexamethylene glycol copolymer polycarbonate used for the production of the toner (13) is purified by repeating reprecipitation using dichloromethane and isopropanol so as to reduce low molecular weight components and impurities.
[0206]
Various physical properties of the obtained toner particles and polymerized toner are shown in Table 1.
[0207]
Toner Production Example 14
To 710 g of ion-exchanged water in a two-liter four-necked flask, 0.1 M Na_Three PO_Four After adding 520 g of the aqueous solution and heating to 60 ° C., the mixture was stirred at 12000 rpm using a high-speed stirring device TK type homomixer (manufactured by Tokushu Kika Kogyo). To this, 1.0M-CaCl₂ 85 g of an aqueous solution was gradually added to obtain an aqueous dispersion medium containing a minute hardly water-soluble dispersion stabilizer.
[0208]
On the other hand, as dispersoid
・ 80 parts by weight of styrene
・ 20 parts by weight of n-butyl acrylate
1-phenyl-1,1-bis (4-hydroxyphenyl) ethane polycarbonate (peak molecular weight: 20000, Mw: 32000, Mn: 10000) 5 parts by weight
・ C. I. Pigment Red 202 (colorant) 5 parts by weight
Charge control agent (2,5-di-tert-butylsalicylic acid Al compound) 2 parts by weight
・ Ester wax (DSC peak 70 ° C) 5 parts by weight
[0209]
Among the above formulations, only a colorant, an Al compound of di-tert-butylsalicylic acid, and styrene were premixed using Ebara Milder (manufactured by Ebara Seisakusho). Next, all the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Further, while maintaining at 60 ° C., 10 g of initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.
[0210]
The monomer composition was charged into a dispersion medium prepared in a 2 liter flask of the homomixer. Using a TK homomixer at 60 ° C. in a nitrogen atmosphere, the mixture was stirred at 10,000 rpm for 20 minutes to granulate the monomer composition. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 10 hours.
[0211]
After completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added and Ca is added._Three (PO_Four )₂ Was dissolved, filtered, washed with water, and dried to obtain colored suspended particles (toner particles) (14) having a weight average diameter of about 7.1 μm.
[0212]
To 100 parts by weight of the obtained toner particles (14), 1.5 parts by weight of hydrophobic silica used in Toner Production Example 1 was externally added to obtain a polymerized toner (14).
[0213]
The 1,1-bis (4-hydroxyphenyl) ethane polycarbonate used in the production of the toner (14) is purified by repeating reprecipitation using dichloromethane and isopropanol so as to reduce low molecular weight components and impurities.
[0214]
Various physical properties of the obtained toner particles and polymerized toner are shown in Table 1.
[0215]
Toner Production Example 15
The following dispersoids were used.
・ 80 parts by weight of styrene
・ 20 parts by weight of n-butyl acrylate
・ 2,2-bis (3-methyl-4-hydroxyphenyl) propane polycarbonate (peak molecular weight: 8000, Mw: 12000, Mn: 4000) 5 parts by weight
・ C. I. Pigment Yellow 17 (colorant) 5 parts by weight
Charge control agent (2,5-di-tert-butylsalicylic acid Al compound) 2 parts by weight
・ Ester wax (DSC peak 70 ° C) 5 parts by weight
[0216]
With the above formulation, toner particles (15) were produced in the same manner as in Toner Production Example 13, and polymerized toner (15) having a weight average diameter of about 7.0 μm was obtained in the same manner.
[0217]
The 2,2-bis (3-methyl-4-hydroxyphenyl) propane polycarbonate used in the production of the toner (15) was purified by repeating reprecipitation using dichloromethane and isopropanol so that low molecular weight components and impurities were reduced. Is.
[0218]
Table 1 shows properties of the obtained polymer toner (15).
[0219]
[Table 1]

[0220]
  <Examples 1 to3, 5-11Comparative Examples 1 to 3Reference examples 1-2>
  A 600 dpi laser beam printer (manufactured by Canon: LBP-860) was prepared as an electrophotographic apparatus. The process speed is modified to 60 mm / s.
[0221]
The cleaning rubber blade in this process cartridge was removed, and the charging method of the apparatus was direct charging performed by contacting a rubber roller, and the applied voltage was a direct current component (-1200 V).
[0222]
Next, the development part in the process cartridge was modified. Medium resistance rubber roller (16φ, hardness ASKER C45 degree, resistance 10) made of silicone rubber dispersed with carbon black instead of stainless steel sleeve as toner supply body^Five (Ω · cm) was used as a toner carrier, and was in contact with the photoreceptor. The developing nip width at this time was set to about 3 mm. The rotational speed of the toner carrier is the same in the contact portion with the photoconductor, and is driven so as to be 150% of the rotational speed of the photoconductor.
[0223]
The photoconductor used here was a 30φ, 254 mm Al cylinder as a substrate, and layers having the following configurations were sequentially laminated by dip coating to produce a photoconductor.
(1) Conductive coating layer: Mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenolic resin. Film thickness 15 μm.
(2) Undercoat layer: mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
(3) Charge generation layer: Mainly composed of a titanyl phthalocyanine pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
(4) Charge transport layer: Mainly composed of a hole transportable triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 by Ostwald viscosity method) at a weight ratio of 8:10. Film thickness 20 μm.
[0224]
As a means for applying the toner to the toner carrier, an application roller made of urethane foam rubber was provided in the developing device and brought into contact with the toner carrier. A voltage of about −550 V is applied to the application roller. Further, a stainless steel blade coated with resin for controlling the coat layer of the toner on the toner carrier was attached so that the contact pressure with the toner carrier was a linear pressure of about 20 g / cm. The outline is shown in FIG. In addition, the applied voltage at the time of development was only a DC component (−450 V).
[0225]
The electrophotographic apparatus was remodeled and process conditions were set as follows in order to conform to the remodeling of these process cartridges.
[0226]
The modified device uses a roller charger (applying only direct current) to uniformly charge the image carrier. Subsequent to charging, an image portion is exposed with laser light to form an electrostatic latent image, and a visible image is formed with toner, and then a toner image is transferred to a transfer material by a roller to which a voltage is applied. The outline is shown in FIG.
[0227]
As for the photosensitive member charging potential, the dark portion potential was set to -600V, and the bright portion potential was set to -150V. As a transfer material, 75 g / m² Paper was used.
[0228]
Using the above image forming apparatus, as shown in Table 2, using pulverized toners (1) and (9), spheroidized toners (2) to (8), and polymerized toners (10) to (15), a temperature of 10 ° C. / The durability test was conducted under the condition of 10% humidity.
[0229]
For durability evaluation, character printing was performed at a printing area ratio of 3%, and evaluation was performed as follows.
[0230]
The toner charging roller contamination was judged by the number of the charged unevenness due to the charging member contamination on the halftone image.
[0231]
In the toner photoconductor fusion and sleeve fusion, the surface of the photoconductor and the sleeve surface were observed when white spots were generated on the solid black image, and the presence or absence of the fusion was confirmed. If no fusion was observed, the durability evaluation was continued.
[0232]
When charging roller contamination, photoconductor fusing, and sleeve fusing did not occur, image printing was continued up to 1500 sheets. The greater the number of sheets generated, the better the durability of the toner.
[0233]
The transferability of the endurance treatment is a numerical value obtained by subtracting the Macbeth density of the tape with only the tape from the Macbeth density of the tape on which the transfer residual toner on the photoconductor was stripped off with Mylar tape after the solid black image was developed. It was evaluated with. Therefore, the smaller the value, the better the transferability.
[0234]
The resolving power in the initial stage of durability was evaluated based on the reproducibility of a small-diameter isolated 1 dot at 600 dpi, which is easy to close due to the latent electric field and difficult to reproduce.
◎ (Very good): Less than 5 defects in 100
○ (Good): 6 to 10 defects in 100
Δ (Normal): 11 to 20 defects in 100
× (Poor): 20 or more defects in 100
[0235]
The anti-offset property was determined by observing the stains occurring on the back side of the image samples from the initial stage to 100 durability sheets and counting the number of generated sheets.
[0236]
The fog was measured using a REFECT METER MODEL TC-6DS manufactured by Tokyo Denshoku Co., Ltd.
[0237]
The filter was calculated from the following formula using an amberlite filter for the polymerized toner (13), a blue filter for the polymerized toner (15), and a green filter for the other toners. The smaller the value, the less fog.
[0238]
Fog amount (%) = (Whiteness before printout) − (Whiteness of non-image forming portion (white background portion) of recording material after printing)
[0239]
The obtained results are shown in Table 2.
[0240]
[Table 2]

[0241]
<Example 13 and Comparative Example 4>
Durability evaluation with a full-color image was performed under the following experimental conditions.
[0242]
FIG. 2 is a schematic view of a cross section of an image forming apparatus applied to Example 12 and Comparative Example 4, and FIG. 3 is a developing device diagram of the image forming apparatus.
[0243]
The photosensitive drum 21 has a photosensitive layer 21b having an organic optical semiconductor on a base material 21a, and is photosensitive by a charging roller 22 (conductive elastic layer 22a, cored bar 22b) that rotates in the direction of an arrow and rotates oppositely. A surface potential of about −600 V is charged on the body drum 21. In exposure 23, an electrostatic charge image having an exposed portion potential of −100 V and a dark portion potential of −600 V is formed on the photosensitive member by a polygon mirror according to digital image information. Polymerized toner (13), polymerized toner (14), polymerized toner (15), and polymerized toner (10) or (14) are introduced into developing devices 24-1, 24-2, 24-3, and 24-4, respectively. Then, the electrostatic latent image formed on the photoconductor 21 is reversely developed by the nonmagnetic one-component method, and each color toner image is formed on the photoconductor 21. The toner images are primary-transferred sequentially onto the intermediate transfer body 25 after development for each color, and finally are secondary-transferred collectively onto the recording material 26. At this time, the toner remaining on the photosensitive member 21 without being transferred is cleaned by the cleaner member 28, and the toner remaining on the intermediate transfer member 25 is cleaned by the cleaner member 29.
[0244]
The intermediate transfer body 25 is obtained by coating an elastic layer 25a in which a carbon black conductivity imparting member is sufficiently dispersed in nitrile-butadiene rubber (NBR) on a pipe-shaped core metal 25b, and the hardness of the coat layer 25a. Is 20 degrees in accordance with “JIS K-6301” and the volume resistivity is 10⁹ Ω · cm. The transfer current required for transfer from the photosensitive member 21 to the intermediate transfer member 25 is about 5 μA, which was obtained by applying +1000 V to the cored bar 25b from the power source.
[0245]
The transfer roller 27 has an outer diameter of 20 mm, and the transfer roller 27 has a carbon conductivity imparting member placed on a core metal 27b having a diameter of 10 mm in an ethylene-propylene-diene terpolymer (EPDM) foam. It has the elastic layer 27a produced | generated by coating what was fully disperse | distributed, The volume specific resistance value of the elastic layer 27a is 10⁶ The standard hardness of “JIS K-6301” in Ω · cm was 35 degrees. A voltage was applied to the transfer roller to pass a transfer current of 15 μA.
[0246]
As the heat fixing device H, a heat roll type fixing device having no oil application function was used.
[0247]
Under the above setting conditions, durability evaluation was performed for a maximum of 1500 continuous images at a temperature of 30 ° C./humidity 80% at a sheet passing speed of 8 sheets / minute (A4 size) with a printing area of 10%.
[0248]
Toner photoreceptor fusion and sleeve fusion were evaluated in the same manner as in Examples 1-12. For fusion on the intermediate transfer member, the surface of the intermediate transfer member was observed at the stage where white spots occurred on the solid black image, and the presence or absence of fusion was confirmed. If no fusion was observed, the durability evaluation was continued.
[0249]
When charging roller contamination, photoconductor fusing, and sleeve fusing did not occur, image printing was continued up to 1500 sheets. The greater the number of sheets generated, the better the durability of the toner.
[0250]
The above evaluation results are summarized in Table 3.
[0251]
[Table 3]

[0252]
【The invention's effect】
As described above, according to the image forming method of the present invention, excellent durability in the contact developing method can be obtained without impairing the fixing property. In particular, when applied to a cleaner-less configuration or a configuration using an intermediate transfer member, excellent developability, transferability, and toner fusing resistance can be stably obtained for a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic view of a one-component image forming apparatus suitable for the present invention.
FIG. 2 is a schematic view of a full-color image forming apparatus using an intermediate transfer member suitable for the present invention.
FIG. 3 is a schematic explanatory view of a developing device suitable for the present invention.
[Explanation of symbols]
21 Photoconductor (electrostatic latent image carrier)
24 Developer
25 Intermediate transfer member
26 Transfer material
27 Transfer means
31 Developing device
34 Developer
35 photoconductor
37 Developer carrier
100 Developer
102 Toner carrier
104 Toner
105 Transfer material
106 Transfer member
109 Photosensitive member (electrostatic image carrier)
110 Primary charging member

Claims (24)

A charging step of charging the electrostatic latent image carrier; an exposure step of forming an electrostatic latent image on the charged electrostatic latent image carrier by exposure; carried on the surface of the electrostatic latent image carrier and the toner carrier A developing step of contacting the toner layer formed by the toner being formed and developing the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image; and the electrostatic latent An image having a transfer step of transferring a toner image formed on an image carrier to a transfer material; a fixing step of fixing the toner image transferred on the transfer material by applying pressure and heat to the transfer material; In the forming method,
The toner carrier has an elastic layer on the surface,
The toner contains at least a binder resin, a colorant and a wax,
The binder resin contains at least a polycarbonate resin ,
The polycarbonate resin has a peak molecular weight in the region of molecular weight 2000 to 100,000 in the molecular weight distribution by gel permeation chromatography (GPC) soluble in tetrahydrofuran (THF),
The toner has a component having in its structure a repeating unit of a polycarbonate resin contained in a component having a molecular weight of 1000 or less in a molecular weight distribution by gel permeation chromatography (GPC) soluble in tetrahydrofuran (THF). An image forming method comprising 5.0% by weight or less based on the weight of the toner .   2. The image forming method according to claim 1, wherein the toner contains 0.1 to 50.0% by weight of a polycarbonate resin with respect to the total binder resin. The binder resin contains 50 to 99.9% by weight of one or more resins selected from the group consisting of styrene-acrylic resins, polyester resins, and epoxy resins, based on the total binder resin. the image forming method according to claim 1 or 2, characterized in that there. The toner image formed according to any one of claims 1 to 3, characterized in that the shape factor SF-1 by the image analysis apparatus 100 to 160 and a shape factor SF-2 has the 100 to 140 Method. The toner image formed according to any one of claims 1 to 4, characterized in that the shape factor SF-1 by the image analysis apparatus 100 to 140 and a shape factor SF-2 has the 100 to 120 Method. 2. The toner according to claim 1, wherein a ratio (SF-2 / SF-1) of a shape factor SF-1 and a shape factor SF-2 by the image analysis apparatus is 1.0 or less. 6. The image forming method according to any one of 5 above. The toner image forming method according to any one of claims 1 to 6, characterized in that it has a weight average particle size of 2Myuemu～10myuemu. The toner image forming method according to any one of claims 1 to 7, characterized in that it has a weight average particle size of 4Myuemu～8myuemu. The toner image forming method according to any one of claims 1 to 8, characterized in that it the wax containing 0.1 to 50 wt% by weight of the toner. The toner image forming method according to any one of claims 1 to 9, characterized in that the wax contains 0.5 to 30 wt% by weight of the toner. The wax, in the DSC curve by differential scanning calorimetry, according to any one of claims 1 to 10, characterized in that it has a maximum endothermic peak at the time of raising the temperature region of 40 to 130 ° C. image Forming method. The image according to any one of claims 1 to 11 , wherein the wax has a maximum endothermic peak at the time of temperature rise in a temperature range of 50 to 100 ° C in a DSC curve obtained by a differential scanning calorimeter. Forming method. The toner image forming method according to any one of claims 1 to 12, characterized in that said polycarbonate resin is present on the surface of the toner particles. It said toner has the polycarbonate resin is present on the surface of the toner particles, in the interior of the toner particles, according to any one of claims 1 to 13, characterized in that the wax is dispersed Image forming method. The polycarbonate-based resin, an image forming method according to claim 13 or 14, characterized in that the continuously present on the surface of the toner particles. The polycarbonate-based resin, an image forming method according to claim 13 or 14, characterized in that it is present discontinuously on the surface of the toner particles. The toner has polymerized toner particles produced by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, a wax and a polycarbonate resin in an aqueous medium. the image forming method according to any one of claims 1 to 16, wherein the. In the development step, the toner is carried on the surface of the toner carrier and developed.
The moving speed of the surface of the toner carrier is set to 1.05 to 3.0 times the moving speed of the surface of the electrostatic latent image carrier,
The toner carrying member, an image forming method according to any one of claims 1 to 17, characterized in that it has a 1.5μm below the surface roughness (Ra). By abutting the elastic blade to the surface of the toner bearing member, the image forming method according to any one of claims 1 to 18 and forming the toner layer on the toner carrying member. In the charging step, according to claim 1 to 19, characterized in that by contacting a charging member external voltage is applied to the surface of the latent electrostatic image bearing member to charge the latent electrostatic image bearing member Any of the image forming methods. An intermediate transfer member is used as the transfer material,
A primary transfer step in which a toner image formed on the electrostatic latent image carrier is primarily transferred onto the intermediate transfer member as the transfer step; A secondary transfer step of performing secondary transfer in a batch; and a fixing step of fixing the first toner image and the second toner image secondarily transferred onto the recording material to the recording material; the image forming method according to any one of claims 1 to 20, characterized in that there. A recording material is used as the transfer material, and the toner image formed on the electrostatic latent image carrier in the transfer step is transferred onto the recording material,
The image forming method according to any one of claims 1 to 21, characterized in that it further comprises a; a toner image transferred onto the recording material, a fixing step of fixing to the recording material. The toner remaining on the surface of the electrostatic latent image carrier after the transfer is collected and cleaned on the surface of the toner carrier, and the collected toner is carried on the surface of the toner carrier to develop the electrostatic latent image again. The image forming method according to any one of claims 1 to 22 , wherein the image formation is achieved by using a developing and cleaning step to be used. A developing section in the developing process, a transferring section in the transferring process, and a charging section in the charging process are arranged in this order along the moving direction of the electrostatic latent image carrier, and between the developing section and the transferring section. There is no cleaning member between the transfer unit and the charging unit between the transfer unit and the charging unit to contact the surface of the electrostatic latent image carrier to remove residual toner. The image forming method according to claim 23 .

Images