JP4148444B2 - Image forming method - Google Patents

Description

【００７２】
【化２】

【００７３】
これらエステルワックスは、樹脂粒子中に含有され、樹脂粒子を融着させて得られるトナーに良好な定着性（画像支持体に対する接着性）を付与する機能を有する。
【００７４】
本発明に用いられる離型剤の添加量は、トナー全体に１質量％〜３０質量％が好ましく、更に好ましくは２質量％〜２０質量％であり、更に好ましくは３〜１５質量％である。また、本発明のトナーは、上記の重合性単量体中に前記離型剤を溶解させたものを水中に分散し、重合させ、樹脂粒子中に離型剤として上記のようなエステル系化合物を内包させた粒子を形成させ、着色剤粒子ととも塩析／融着する工程を経て作製されたトナーが好ましい。
【００７５】
本発明に係るトナーは、着色剤、離型剤以外にトナー用材料として種々の機能を付与することのできる材料を加えてもよい。具体的には荷電制御剤等が挙げられる。これらの成分は前述の塩析／融着段階で樹脂粒子と着色剤粒子と同時に添加し、トナー中に包含する方法、樹脂粒子自体に添加する方法等種々の方法で添加することができる。
【００７６】
荷電制御剤も同様に種々の公知のもので、且つ水中に分散することができるものを使用することができる。具体的には、ニグロシン系染料、ナフテン酸または高級脂肪酸の金属塩、アルコキシル化アミン、第４級アンモニウム塩化合物、アゾ系金属錯体、サリチル酸金属塩あるいはその金属錯体等が挙げられる。
【００７７】
本発明に係るトナーに用いられる外添剤について説明する。
本発明に係るトナーには、流動性、帯電性の改良およびクリーニング性の向上などの目的で、いわゆる外添剤を添加して使用することができる。これら外添剤としては特に限定されないが、種々の無機微粒子、有機微粒子及び滑剤を使用することができる。
【００７８】
無機微粒子としては、従来公知のものを使用することができる。具体的には、シリカ、チタン、アルミナ微粒子等が好ましく用いることができる。これら無機微粒子としては疎水性のものが好ましい。具体的には、シリカ微粒子として、例えば日本アエロジル社製の市販品Ｒ−８０５、Ｒ−９７６、Ｒ−９７４、Ｒ−９７２、Ｒ−８１２、Ｒ−８０９、ヘキスト社製のＨＶＫ−２１５０、Ｈ−２００、キャボット社製の市販品ＴＳ−７２０、ＴＳ−５３０、ＴＳ−６１０、Ｈ−５、ＭＳ−５等が挙げられる。
【００７９】
チタン微粒子としては、例えば、日本アエロジル社製の市販品Ｔ−８０５、Ｔ−６０４、テイカ社製の市販品ＭＴ−１００Ｓ、ＭＴ−１００Ｂ、ＭＴ−５００ＢＳ、ＭＴ−６００、ＭＴ−６００ＳＳ、ＪＡ−１、富士チタン社製の市販品ＴＡ−３００ＳＩ、ＴＡ−５００、ＴＡＦ−１３０、ＴＡＦ−５１０、ＴＡＦ−５１０Ｔ、出光興産社製の市販品ＩＴ−Ｓ、ＩＴ−ＯＡ、ＩＴ−ＯＢ、ＩＴ−ＯＣ等が挙げられる。
【００８０】
アルミナ微粒子としては、例えば、日本アエロジル社製の市販品ＲＦＹ−Ｃ、Ｃ−６０４、石原産業社製の市販品ＴＴＯ−５５等が挙げられる。
【００８１】
また、有機微粒子としては数平均一次粒子径が１０〜２０００ｎｍ程度の球形の有機微粒子を使用することができる。このものとしては、スチレンやメチルメタクリレートなどの単独重合体やこれらの共重合体を使用することができる。
【００８２】
滑剤には、例えばステアリン酸の亜鉛、アルミニウム、銅、マグネシウム、カルシウム等の塩、オレイン酸の亜鉛、マンガン、鉄、銅、マグネシウム等の塩、パルミチン酸の亜鉛、銅、マグネシウム、カルシウム等の塩、リノール酸の亜鉛、カルシウム等の塩、リシノール酸の亜鉛、カルシウムなどの塩等の高級脂肪酸の金属塩が挙げられる。
【００８３】
これら外添剤の添加量は、トナーに対して０．１〜５質量％が好ましい。
外添剤の添加方法としては、タービュラーミキサー、ヘンシエルミキサー、ナウターミキサー、Ｖ型混合機などの種々の公知の混合装置が挙げられる。
【００８４】
本発明に係る静電荷像現像用トナーの製造方法について説明する。
《製造工程》
本発明のトナーは、離型剤を溶解した上記記載のような重合性単量体または重合性単量体溶液を水系媒体中に分散し、ついで重合法により離型剤を内包した樹脂粒子を調整する工程、前記樹脂粒子分散液を用いて水系媒体中で樹脂粒子を融着させる工程、得られた粒子を水系媒体中より濾過し界面活性剤などを除去する洗浄工程、得られた粒子を乾燥させる工程、さらに乾燥させて得られた粒子に外添剤などを添加する外添剤添加工程などから構成される重合法で製造することが好ましい。ここで樹脂粒子としては着色された粒子であってもよい。また、非着色粒子を樹脂粒子として使用することもできる、この場合には、樹脂粒子の分散液に着色剤粒子分散液などを添加した後に水系媒体中で融着させることで着色粒子とすることができる。
【００８５】
特に、融着の方法としては、重合工程によって生成された樹脂粒子を用いて塩析／融着する方法が好ましい。また、非着色の樹脂粒子を使用した場合には、樹脂粒子と着色剤粒子を水系媒体中で塩析／融着させることができる。
【００８６】
また、着色剤や離型剤に限らず、トナーの構成要素である荷電制御剤等も本工程で粒子として添加することができる。
【００８７】
なお、ここで水系媒体とは主成分として水からなるもので、水の含有量が５０質量％以上であるものを示す。水以外のものとしては、水に溶解する有機溶媒を挙げることができ、例えば、メタノール、エタノール、イソプロパノール、ブタノール、アセトン、メチルエチルケトン、テトラヒドロフランなどをあげることができる。好ましくは樹脂を溶解しない有機溶媒である、メタノール、エタノール、イソプロパノール、ブタノールのようなアルコール系有機溶媒が特に好ましい。
【００８８】
本発明での好ましい重合法としては、モノマー中に離型剤を溶解したモノマー溶液を臨界ミセル濃度以下の界面活性剤を溶解させた水系媒体中に機械的エネルギーによって油滴分散させた分散液に、水溶性重合開始剤を加え、ラジカル重合させる方法をあげることができる。この場合、モノマー中に油溶性の重合開始剤を加えて使用してもよい。
【００８９】
この油滴分散を行うための分散機としては特に限定されるものでは無いが、例えばクレアミックス、超音波分散機、機械式ホモジナイザー、マントンゴーリンや圧力式ホモジナイザー等をあげることができる。
【００９０】
着色剤自体は表面改質して使用してもよい。着色剤の表面改質法は、溶媒中に着色剤を分散し、その中に表面改質剤を添加した後昇温し反応を行う。反応終了後、ろ過し同一の溶媒で洗浄ろ過を繰り返し乾燥させ表面改質剤で処理された顔料を得る。
【００９１】
着色剤粒子は着色剤を水系媒体中に分散して調製される方法がある。この分散は、水中で界面活性剤濃度を臨界ミセル濃度（ＣＭＣ）以上にした状態で行われることが好ましい。
【００９２】
顔料分散時の分散機は特に限定されないが、好ましくはクレアミックス、超音波分散機、機械的ホモジナイザー、マントンゴーリンや圧力式ホモジナイザー等の加圧分散機、サンドグラインダー、ゲッツマンミルやダイヤモンドファインミル等の媒体型分散機が挙げられる。
【００９３】
ここで使用される界面活性剤は、前述の界面活性剤を使用することができる。
塩析／融着を行う工程は、樹脂粒子及び着色剤粒子とが存在している水中にアルカリ金属塩やアルカリ土類金属塩等からなる塩析剤を臨界凝集濃度以上の凝集剤として添加し、ついで樹脂粒子のガラス転移点以上に加熱することで塩析を進行させると同時に融着を行う工程である。
【００９４】
ここで、塩析剤であるアルカリ金属塩及びアルカリ土類金属塩は、アルカリ金属として、リチウム、カリウム、ナトリウム等が挙げられ、アルカリ土類金属として、マグネシウム、カルシウム、ストロンチウム、バリウムなどが挙げられ、好ましくはカリウム、ナトリウム、マグネシウム、カルシウム、バリウムが挙げられる。また塩を構成するものとしては、塩素塩、臭素塩、沃素塩、炭酸塩、硫酸塩等が挙げられる。
【００９５】
トナーの粒径分布を達成するための方法としては特に限定されないが、例えば分級などの手法による制御や会合時における温度や時間、さらには会合を終了させるための停止方法の制御などの手法を使用することができる。
【００９６】
特に好ましい製造方法として、水中での会合時間、会合温度、停止速度などを制御する方法をあげることができる。すなわち、塩析／融着で行う場合、塩析剤を添加した後に放置する時間をできるだけ短くすることが好ましい。この理由として明確では無いが、塩析した後の放置時間によって、粒子の凝集状態が変動し、粒径分布が不安定になったり、融着させたトナーの表面性が変動したりする問題が発生する。この塩析剤を添加する温度は特に限定されない。
【００９７】
本発明では、樹脂粒子の分散液をできるだけ速やかに昇温し、樹脂粒子のガラス転移温度以上に加熱する方法を使用することが好ましい。この昇温までの時間としては３０分未満、好ましくは１０分未満である。さらに、昇温を速やかに行う必要があるが、昇温速度としては、１℃／分以上が好ましい。上限としては特に明確では無いが、急速な塩析／融着の進行により粗大粒子の発生を抑制する観点で、１５℃／分以下が好ましい。特に好ましい形態としては、塩析／融着をガラス転移温度以上になった時点でも継続して進行させる方法をあげることができる。この方法とすることで、粒子の成長とともに融着が効果的に進行させることができ、最終的なトナーとしての耐久性を向上することができる。
【００９８】
さらに、会合時に２価の金属塩を使用して塩析／融着することで特に粒径を制御することが可能となる。この理由としては明確ではないが、２価の金属塩を使用することで塩析時の斥力が大きくなり、界面活性剤の分散能を効果的に抑制することが可能となり、結果として流刑分布を制御することが可能となったものと推定される。
【００９９】
また、塩析／融着を停止するために１価の金属塩及び水を添加することが好ましい。このものを添加することにより、塩析を停止させることができ、結果として大粒径成分や小粒径成分の存在を抑制することが可能となる。
【０１００】
樹脂粒子を水系媒体中で会合あるいは融着させる重合法トナーでは、融着段階での反応容器内の媒体の流れおよび温度分布を制御することで、さらには融着後の形状制御工程において加熱温度、攪拌回転数、時間を制御することで、トナー全体の形状分布および形状を任意に変化させることができる。
【０１０１】
すなわち、樹脂粒子を会合あるいは融着させる重合法トナーでは、反応装置内の流れを層流とし、内部の温度分布を均一化することができる攪拌翼および攪拌槽を使用して、融着工程および形状制御工程での温度、回転数、時間を制御することにより、本発明の形状係数および均一な形状分布を有するトナーを形成することができる。この理由は、層流を形成させた場で融着させると、凝集および融着が進行している粒子（会合あるいは凝集粒子）に強いストレスが加わらず、かつ流れが加速された層流においては攪拌槽内の温度分布が均一である結果、融着粒子の形状分布が均一になると推定される。さらに、その後の形状制御工程での加熱、攪拌により融着粒子は徐々に球形化し、トナー粒子の形状を任意に制御できる。
【０１０２】
本発明のトナーを所定の形状に制御するためには、塩析と融着を同時進行させることが好ましい。凝集粒子を形成した後に加熱する方法ではその形状に分布を生じやすく、さらに微粒子の発生を抑制することができない。すなわち、凝集粒子を水系媒体中で攪拌しながら加熱するために凝集粒子の再分断が発生し、小粒径の成分が発生しやすいものと推定される。
【０１０３】
本発明に用いられる現像剤について説明する。
キャリアと混合して二成分現像剤として用いること場合にはキャリアの磁性粒子として、鉄、フェライト、マグネタイト等の金属、それらの金属とアルミニウム、鉛等の金属との合金等の従来から公知の材料を用いることが出来る。特にフェライト粒子が好ましい。上記磁性粒子は、その体積平均粒径としては１５〜１００μｍ、より好ましくは２５〜８０μｍのものがよい。
【０１０４】
キャリアの体積平均粒径の測定は、代表的には湿式分散機を備えたレーザ回折式粒度分布測定装置「ヘロス（ＨＥＬＯＳ）」（シンパティック（ＳＹＭＰＡＴＥＣ）社製）により測定することができる。
【０１０５】
キャリアは、磁性粒子が更に樹脂により被覆されているもの、あるいは樹脂中に磁性粒子を分散させたいわゆる樹脂分散型キャリアが好ましい。コーティング用の樹脂組成としては、特に限定は無いが、例えば、オレフィン系樹脂、スチレン系樹脂、スチレン−アクリル系樹脂、シリコーン系樹脂、エステル系樹脂或いはフッ素含有重合体系樹脂等が用いられる。また、樹脂分散型キャリアを構成するための樹脂としては、特に限定されず公知のものを使用することができ、例えば、スチレン−アクリル系樹脂、ポリエステル樹脂、フッ素系樹脂、フェノール樹脂等を使用することができる。
【０１０６】
本発明に係る静電潜像担持体（感光体ともいう）について説明する。
本発明に係る感光体としては、有機感光体が好ましく用いられる。前記有機感光体の好ましい構成としては、図１（１）〜（６）を用いて説明する。
【０１０７】
ここで、図１（１）〜（６）は、各々、本発明に用いられる感光体の一態様を示す概略断面図である。
【０１０８】
図１（１）は導電性支持体１上に中間層２を介して電荷発生物質（ＣＧＭ）と電荷輸送物質（ＣＴＭ）を共に含有する単層構成の感光層６を有する感光体であり、図１（２）は導電性支持体１上に中間層２を介して電荷輸送物質を主成分として含有する電荷輸送層（ＣＴＬ）３と電荷発生物質（ＣＧＭ）を主成分として含有する電荷発生層（ＣＧＬ）４とをその順に積層してなる感光層６を有する感光体であり、図１（３）は導電性支持体１上に中間層２を介して電荷発生物質（ＣＧＭ）を主成分として含有する電荷発生層（ＣＧＬ）４と電荷輸送物質を主成分として含有する電荷輸送層（ＣＴＬ）３とをその順に積層してなる感光層６を有する感光体である。図１（４）、（５）、（６）は、各々、図１（１）、（２）、（３）の感光層６の上に保護層５を積層した構成を示す。
【０１０９】
これらの図１（１）〜（６）に示した断面図は代表的な構成を示したもので、この構成に限定されない。また、これらの構成で示した中間層２は必要に応じて設けるもので塗設してもよいし、また、しなくてもよい。また、前記中間層には酸化チタンの様な半導電性微粒子を添加してもよい。
【０１１０】
保護層５にはシリカや有機微粒子を添加することもできる。さらに、保護層中にＣＴＭを添加してもよい。
【０１１１】
図１（１）〜（６）に示す感光体に使用される電荷発生物質（ＣＧＭ）としては。例えばフタロシアニン顔料、多環キノン顔料、アゾ顔料、ペリレン顔料、インジゴ顔料、キナクリドン顔料、アズレニウム顔料、スクワリリウム染料、シアニン染料、ピリリウム染料、チオピリリウム染料、キサンテン色素、トリフェニルメタン系色素、スチリル系色素等をあげることができ、これらは単独あるいは混合して適当なバインダ樹脂と共に層形成される。
【０１１２】
特に好ましいＣＧＭとしては、フタロシアニン顔料があり、特にＣｕ−Ｋα線に対するブラッグ角２θが２７．２°に最大ピークを有するチタニルフタロシアニン型顔料、例えば同２θが１２．４°に最大ピークを有するビスベンゾイミダゾールペリレンをあげることができる。
【０１１３】
電荷輸送層を構成するバインダとしては公知の樹脂を使用することができるが、好ましい樹脂として、ホルマール樹脂、ブチラール樹脂、シリコン樹脂、シリコン変性ブチラール樹脂、フェノキシ樹脂等をあげることができる。バインダ樹脂とＣＧＭとの割合は、バインダ樹脂１００質量部に対して２０〜６００質量部であるが好ましい。ＣＧＬ層の膜厚は０．０１〜２μｍが好ましい。
【０１１４】
また、感光層６に含有される電荷輸送物質（ＣＴＭ）としては、例えばオキサゾール誘導体、オキサジアゾール誘導体、チアゾール誘導体、トリアゾール誘導体、イミダゾール誘導体、イミダゾリン誘導体、イミダゾロン誘導体、ビスイミダゾリジン誘導体、スチリル系誘導体、ヒドラゾン系誘導体、ベンジジン系誘導体、ピラゾリン誘導体、スチルベン系誘導体、アミン誘導体、オキサゾロン誘導体、ベンゾチアゾール誘導体、ベンズイミダゾール誘導体、キナゾリン誘導体、ベンゾフラン誘導体、アクリジン誘導体、フェナジン誘導体、アミノスチルベン誘導体、ポリ−Ｎ−カルバゾール、ポリ−１−ビニルピレン、ポリ−９−ビニルアントラセンなどがあげられる。これらＣＴＭは通常バインダと共に層形成を行うことができる。
【０１１５】
中でも、本発明に用いられる、特に好ましいＣＴＭとしては、下記一般式（３）で表されるトリフェニルアミンスチリル化合物が挙げられる。
【０１１６】
【化３】

【０１１７】
一般式（３）中、Ｒ₁〜Ｒ₃は各々、水素原子、ハロゲン原子、炭素数１〜５のアルキル基またはアルコキシ基を表す。ｌ，ｍ，ｎは０〜３の整数を表す。Ａｒは水素原子またはアリール基を表す。前記アリール基は、未置換でもよく置換基を有していても良いが、置換基としては、水素原子、ハロゲン原子、炭素数１〜５のアルキル基またはアルコキシ基等が挙げられる。アリール基の中では特にフェニル基が好ましい。
【０１１８】
一般式（３）で表されるトリフェニルアミンスチリル化合物の具体例を下記に示すが、本発明はこれらに限定されない。
【０１１９】
【化４】

【０１２０】
【化５】

【０１２１】
【化６】

【０１２２】
【化７】

【０１２３】
【化８】

【０１２４】
【化９】

【０１２５】
これら電荷輸送層に含有されるバインダとしては、ポリカーボネーチ樹脂、ポリエステル、スチレン系樹脂、アクリル樹脂、塩化ビニル樹脂、ポリビニルブチラール、ポリビニルアセタール、スチレン−ブタジエン樹脂、ウレタン樹脂、シリコーン樹脂、フェノール樹脂などをあげることができ、特に好ましいバインダとしては、ポリカーボネート樹脂をあげることができる。
【０１２６】
ＣＴＬは前記ＣＴＭを前述の有機溶媒にバインダ樹脂とを溶解して塗布乾燥することで形成される。ＣＴＬ中のＣＴＭとバインダ樹脂との比率は質量比で３：１〜１：３が好ましい。
【０１２７】
また、ＣＴＬが複数形成される場合には、最上層に形成されるＣＴＬに含有されるバインダ樹脂の分子量が高いことが好ましい。この構成とすることで、機械的強度を向上することができるためである。
【０１２８】
特に最上層のＣＴＬに使用されるバインダ樹脂としてのポリカーボネート樹脂の分子量は粘度平均分子量で５０，０００以上であることが好ましく、特に好ましくは１００，０００〜５００，０００のものである。また、その下層に形成されるＣＴＬ中に含有されるポリカーボネート樹脂の粘度平均分子量は最上層のものよりも小さいことが好ましい。この場合の好ましい分子量範囲は５０，０００未満で、好ましくは２０，０００〜４０，０００である。この構成とすることで、機械的な耐研磨性を向上することができ、薄膜感光体での膜厚変動を極小化することができる。
【０１２９】
感光体を構成するための導電性支持体としては、
（１）アルミニウム、ステンレスなどの導電性金属、
（２）紙あるいはプラスチックフィルム等の絶縁性基体表面にアルミニウム、パラジウム、金等の導電性金属をラミネートあるいは蒸着などでコーティングしたもの、
（３）紙あるいはプラスチックフィルム等の絶縁性基体表面に導電性ポリマー、酸化インジウム、酸化錫などの導電性化合物の層を塗布もしくは蒸着で形成したもの等が挙げられる。
【０１３０】
本発明に係る感光体を製造するための塗布方法としては、浸漬塗布、特開平３−９０２５０号公報や特開平３−２６９２３８号公報記載のスプレー塗布、特開昭５８−１８９０６１号公報に記載の円形量規制型塗布などの塗布方法がある。この中でも円形量規制型塗布方法が積層構造を製造する方法として、下層を溶解することなく上層を塗布することができる為、好ましく用いられる。
【０１３１】
本発明の画像形成方法について説明する。
本発明の画像形成方法は、静電潜像担持体上に潜像を形成する潜像形成工程と、該潜像をトナーを用いて顕像化する現像工程と、前記潜像担持体上に形成したトナー画像を被転写体上に転写する転写工程と、該トナー画像を該被転写体上に定着する定着工程を少なくとも有する画像形成方法であり、前記トナーとして請求項１に記載の静電荷像現像用トナーが用いられる。
【０１３２】
また、本発明の画像形成方法においては、薄層化させた非磁性トナーを静電潜像形成体表面に供給して潜像を現像する方式が好ましい。
【０１３３】
本発明の画像形成方法に係る画像形成装置は、トナー搬送部材、トナー層規制部材及びトナー補給補助部材を備え、且つ、トナー補給補助部材とトナー搬送部材、及びトナー層規制部材とトナー搬送部材がそれぞれ当接していることが好ましい。
【０１３４】
トナー搬送部材は非磁性トナーを電子写真感光体等の静電潜像形成体に供給するものであり、該部材としては、静電潜像形成体に接触させた状態で充分な現像領域を確保する観点から、弾性を有する部材が好ましい。
【０１３５】
本発明において、トナー搬送部材にはウレタンゴム、シリコーンゴムのローラや、導電性の無端ベルト状部材（具体的にはニッケルやＰＥＴベース表面に導電性材料をコーティングしたもの等）の内部にスポンジローラを内包したもの等が好ましく使用される。
【０１３６】
トナー層規制部材はトナー搬送部材に対してトナーを均一に塗布するとともに摩擦帯電を付与する機能を有し、具体的には、ウレタンゴム、金属板等の弾性体が用いられる。前記のトナー層規制部材をトナー搬送部材に当接してトナーの薄層をトナー搬送部材上に形成する。前記トナーの薄層とは現像領域においてトナーが最大で１０層、好ましくは５層以下の状態で形成される層である。
【０１３７】
尚、本発明においては、トナー搬送の均一化による搬送ムラの発生や画像上の白すじ発生の防止の観点から、トナー層規制部材はトナー搬送部材に対して１００ｍＮ／ｃｍ〜５Ｎ／ｃｍの圧力で当接されていることが好ましいく、更に好ましくは２００ｍＮ／ｃｍ〜４Ｎ／ｃｍである。
【０１３８】
トナー補給補助部材はトナー搬送部材に対してトナーを安定に供給するためのユニットである。このものとしては、撹拌羽根の付いた水車状のローラあるいはスポンジ状のローラを使用することができる。本発明においては、トナー供給の安定化、スジ状の画像不良発生防止の観点から、トナー補給部材は、トナー搬送部材に対して直径が０．２倍から１．５倍の範囲のものが好ましい。
【０１３９】
次に、本発明の画像形成方法に用いられる現像器（現像装置）の一態様を図２を用いて具体的に説明する。
【０１４０】
図２は本発明の画像形成方法に用いられる現像器の概略断面図である。
図２においてトナータンク１７に内蔵された非磁性一成分トナー１６は、トナー補給補助部材としての撹拌羽根１５により、同じくトナー補給補助部材としてのスポンジローラ１４上に強制的に搬送供給される。スポンジローラ１４上に組込まれたトナーはこのスポンジローラ１４の矢印方向の回転によりトナー搬送部材としてのゴムローラ１２上に搬送され、ゴムローラ１２との摩擦によりその表面に静電的、且つ物理的に吸着される。一方、こうしてゴムローラ１２上に付着したトナーはゴムローラ１２の矢印方向の回転及びトナー層厚規制部材としてのスチール製弾性ブレード１３により均一に薄層化されると共に摩擦帯電する。
【０１４１】
こうしてゴムローラ１２上に形成されたトナー薄層は静電潜像担持体としての電子写真感光体ドラム（感光体）１１の表面と接触または近接により潜像が現像される。尚、本発明の画像形成方法で用いられる現像器は図２に限定されない。
【０１４２】
本発明に使用される定着方法としては、いわゆる接触加熱方式が好ましい定着方法として挙げられる。特に、接触加熱方式として、熱圧定着方式、さらには熱ローラ定着方式および固定配置された加熱体を内包した回動する加圧部材により定着する圧接加熱定着方式をあげることができる。
【０１４３】
熱ロール定着方式では、多くの場合表面にテトラフルオロエチレンやポリテトラフルオロエチレン−パーフルオロアルコキシビニルエーテル共重合体類等を被覆した鉄やアルミニウム等で構成される金属シリンダー内部に熱源を有する上ローラとシリコーンゴム等で形成された下ローラとから形成されている。熱源としては、線状のヒーターを有し、上ローラの表面温度を１２０〜２００℃程度に加熱するものが代表例である。定着部に於いては上ローラと下ローラ間に圧力を加え、下ローラを変形させ、いわゆるニップを形成する。ニップ幅としては１〜１０ｍｍ、好ましくは１．５〜７ｍｍである。定着線速は４０ｍｍ／ｓｅｃ〜６００ｍｍ／ｓｅｃが好ましい。ニップが狭い場合には熱を均一にトナーに付与することができなくなり、定着のムラを発生する。一方でニップ幅が広い場合には樹脂の溶融が促進され、定着オフセットが過多となる問題を発生する。
【０１４４】
また、本発明に用いられる画像形成装置には、定着クリーニングの機構を付与することが好ましい。定着クリーニング機構としては、シリコーンオイルを定着の上ローラあるいはフィルムに供給する方式やシリコーンオイルを含浸したパッド、ローラ、ウェッブ等でクリーニングする方法が使用できる。また、本発明には固定配置された加熱体を内包した回動する加圧部材により定着する方式も好ましく用いることが出来る。
【０１４５】
この定着方式は、固定配置された加熱体と、該加熱体に対向圧接し、且つフィルムを介して記録材を加熱体に密着させる加圧部材とにより圧接加熱定着する方式であり、圧接加熱定着に用いられる定着器は、加熱体が従来の加熱ローラに比べて熱容量が小さく、記録材の通過方向と直角方向にライン状の加熱部を有するものであり、通常加熱部の最高温度は１００〜３００℃に調整されることが好ましい。
【０１４６】
本発明の画像形成方法に用いられる画像形成装置は、トナーリサイクル機構を有するものが好ましく用いられる。
【０１４７】
以下に、図３を用いて、トナーリサイクル装置の一態様を示す。
図中、２１は現像器、２２は現像剤搬送スリーブ、２３は現像剤搬送スクリュー、１１は電子写真感光体ドラム（感光体）、２５はクリーナー部、２６はクリーニング部材（弾性ブレード）、２７はリサイクルトナー回収スクリュー、２８はリサイクルトナー搬送スクリューを示す。
【０１４８】
図３において、クリーニング部材２６により掻き取られた転写残トナーは、リサイクルトナー回収スクリュー２７によりクリーナー部より搬送され、リサイクルトナー搬送スクリュー２８より再び現像器２１に供給される。
【０１４９】
尚、本発明で用いられるトナーリサイクル機構は図３に限定されない。
トナーリサイクル方式としては、上記の他に、感光体に現像され、紙等に転写せずに感光体上に残存したトナーをブレードなどで回収し、現像器に搬送する方式をあげることができる。現像器には直接戻しても良く、いったん補給トナーとリサイクル回収トナーとを中間タンクなどで事前に混合してから現像器に供給する方式等も用いることが出来る。
【０１５０】
本発明に用いられる画像形成装置の例を図４に示すようなカラー電子写真画像形成装置を用いて示す。
【０１５１】
図４は本発明に用いられるカラー電子写真画像形成装置の一例を示す概略構成図である。
【０１５２】
カラー電子写真画像形成装置の本体内には第１、第２、第３及び第４画像形成部Ｐａ、Ｐｂ、Ｐｃ及びＰｄが並列設置される。各画像形成部は同様の構成とされ、各々異なった色の可視像（トナー像）を形成する。
【０１５３】
画像形成部Ｐａ、Ｐｂ、Ｐｃ及びＰｄは、それぞれ専用の静電潜像担持体（電子写真感光体ドラム）１ａ、１ｂ、１ｃ及び１ｄを具備する。各画像形成部Ｐａ、Ｐｂ、Ｐｃ及びＰｄにて形成された電子写真感光体ドラム（感光体ドラムと略すことがある）１ａ、１ｂ、１ｃ及び１ｄ上の画像は、各画像形成部に隣接して移動する記録材担持体１８上に担持し搬送される記録材（転写材、画像支持体）上に転写される。更に、記録材上の画像は、定着部（定着器）１０にて加熱及び加圧して定着され、記録材はトレイ６１へと排出される。
【０１５４】
次に、各画像形成部における潜像形成部について説明する。感光体ドラム１ａ、１ｂ、１ｃ、１ｄの外周には、各々除電露光ランプ２１ａ、２１ｂ、２１ｃ、２１ｄ、ドラム帯電器２ａ、２ｂ、２ｃ、２ｄ、像露光手段としてのレーザビーム露光装置１７ａ、電位センサ２２ａ、２２ｂ、２２ｃ、２２ｄが設けられている。除電露光ランプ２１ａ、２１ｂ、２１ｃ、２１ｄにより除電された感光体ドラム１ａ、１ｂ、１ｃ、１ｄは、ドラム帯電器２ａ、２ｂ、２ｃ、２ｄにより一様に帯電され、次いで、レーザビーム露光装置１７ａにより露光されることにより、感光体ドラム１ａ、１ｂ、１ｃ、１ｄの上には、画像信号に応じた色分解された静電潜像が形成される。本発明の画像形成装置は、像露光手段としては、上述のレーザビーム露光装置１７ａの他に、ＬＥＤアレー露光装置などのように、基本画像単位（画素）においてオフ以外の光量レベルが複数の光を照射可能な、周知の多値露光手段を好適に採用し得る。
【０１５５】
前記感光体ドラム上の静電潜像は、現像手段にて現像され可視像とされる。つまり、現像手段は、それぞれシアン色、マゼンタ色、イエロー色、ブラック色の現像剤を所定量充填された現像器３ａ、３ｂ、３ｃ、３ｄを備えており、上記感光体ドラム１ａ、１ｂ、１ｃ、１ｄに形成された静電潜像を現像し、可視画像（トナー像）とする。
【０１５６】
次に、転写部について説明する。記録材カセット６０中に保持された記録材は、レジストローラを経て記録材担持体１８へと送給される。
【０１５７】
この記録材担持体１８が回転し始めると、記録材がレジストローラから記録材担持体１８上へと搬送される。このとき画像書き出し信号がＯＮとなり、適正なタイミングにより第１の電子写真感光体ドラム１ａ上に画像形成を行う。
【０１５８】
第１の電子写真感光体ドラム１ａの下方には、転写帯電器４ａ及び転写押圧部材４１ａが設けていて、転写押圧部材４１ａにて感光体ドラムの方へと均一な押力を付与し、且つ、転写帯電器４ａが電界を付与することにより感光体ドラム１ａ上のトナー像を記録材上へと転写させる。このとき、記録材は、記録材担持体１８上に静電吸着力で保持され、第２の画像形成部Ｐｂへと記録材は搬送され、次の転写が行なわれる。以下、上記と同様な方法により第３、第４の画像形成部Ｐｃ、Ｐｄによって形成されたトナー像が転写された記録材は、分離帯電器（分離極）９によって除電され、静電吸着力の減衰によって記録材担持体１８から離脱し、定着部（定着器）１０へと搬送される。
【０１５９】
定着部１０は、定着ローラ７１、加圧ローラ７２、ローラ７１、７２をそれぞれクリーニングする耐熱性クリーニング部材７３、７４、各ローラ７１、７２を加熱するヒータ７５、７６、ジメチルシリコーンなどの離型剤オイルを定着ローラ７１に塗布するオイル塗布ローラ７７、そのオイルを供給するためのオイル溜め７８、定着温度制御用のサーミスタ７９から構成されている。
【０１６０】
転写後、感光体ドラムｌａ、ｌｂ、ｌｃ、ｌｄ上に残留したトナー等は、感光体クリーニング部５ａ、５ｂ、５ｃ、５ｄにより除去され、引き続き行われる次の潜像形成に備えられる。又、画像支持体８上に残留したトナー等は、ベルト除電器１２によって除電され静電吸着力を取り除かれた後、本例では不織布を備えたクリーニング装置６２にて除去される。クリーニング装置６２としては回転するファーブラシとか、ブレードとか、これらを併用した装置等も用いられる。
【０１６１】
【実施例】
以下、実施例により本発明を詳細に説明するが、本発明はこれらに限定されない。
【０１６２】
実施例１
《ラテックス１の調製》
撹拌装置、温度センサー、冷却管、窒素導入装置を付けた５０００ｍｌのセパラブルフラスコに予めアニオン系活性剤（ドデシルベンゼンスルフォン酸ナトリウム：ＳＤＳ）７．０８ｇをイオン交換水（２７６０ｇ）に溶解させた溶液を添加する。窒素気流下２３０ｒｐｍの撹拌速度で撹拌しつつ、内温を８０℃に昇温させた。一方で例示化合物１９）７２．０ｇをスチレン１１５．１ｇ、ｎ−ブチルアクリレート４２．０ｇ、メタクリル酸１０．９ｇからなるモノマーに加え、８０℃に加温し溶解させ、モノマー溶液を作製した。ここで循環経路を有する機械式分散機により上記の加熱溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を作製した。ついで、重合開始剤（過硫酸カリウム：ＫＰＳ）０．８４ｇをイオン交換水２００ｇに溶解させた溶液を添加し８０℃にて３時間加熱、撹拌することでラテックス粒子を作製した。引き続いて更に重合開始剤（ＫＰＳ）７．７３ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、１５分後、８０℃でスチレン３８３．６ｇ、ｎ−ブチルアクリレート１４０．０ｇ、メタクリル酸３６．４ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル１４．０ｇの混合液を１２０分かけて滴下した。滴下終了後６０分加熱撹拌させた後４０℃まで冷却しラテックス粒子を得た。
【０１６３】
このラテックス粒子をラテックス１とする。
《着色粒子の製造》
（着色粒子１Ｂｋの製造）
ｎ−ドデシル硫酸ナトリウム＝９．２ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、リーガル３３０Ｒ（キャボット社製カーボンブラック）２０ｇを徐々に加え、ついで、クレアミックスを用いて分散した。大塚電子社製の電気泳動光散乱光度計ＥＬＳ−８００を用いて、上記分散液の粒径を測定した結果、重量平均径で１１２ｎｍであった。この分散液を「着色剤分散液１」とする。
【０１６４】
前述の「ラテックス１」１２５０ｇとイオン交換水２０００ｍｌ及び「着色剤分散液１」を、温度センサー、冷却管、窒素導入装置、攪拌装置を付けた５リットルの四つ口フラスコに入れ撹拌する。３０℃に調整した後、この溶液に５モル／リットルの水酸化ナトリウム水溶液を加え、ｐＨを１０．０に調整した。ついで、塩化マグネシウム６水和物５２．６ｇをイオン交換水７２ｍｌに溶解した水溶液を攪拌下、３０℃にて５分間で添加した。その後、２分間放置した後に、昇温を開始し、液温度９０℃まで５分で昇温する（昇温速度＝１２℃／分）。その状態で粒径をコールターカウンターＴＡIIにて測定し、体積平均粒径が４．３μｍになった時点で塩化ナトリウム１１５ｇをイオン交換水７００ｍｌに溶解した水溶液を添加し粒子成長を停止させ、さらに継続して液温度８５℃±２℃にて、８時間加熱撹拌し、塩析／融着させる。その後、６℃／ｍｉｎの条件で３０℃まで冷却し、塩酸を添加し、ｐＨを２．０に調整し、撹拌を停止した。生成した着色粒子を下記条件で濾過／洗浄し、その後、４０℃の温風で乾燥し、着色粒子を得た。このものを「着色粒子１Ｂｋ」とする。
【０１６５】
（着色粒子１Ｙの製造）
着色粒子１Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントイエロー１８５を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｙ」とする。
【０１６６】
（着色粒子１Ｍの製造）
着色粒子１Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントレッド１２２を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｍ」とする。
【０１６７】
（着色粒子１Ｃの製造）
着色粒子１Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントブルー１５：３を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｃ」とする。
【０１６８】
（着色粒子２Ｂｋ、３Ｂｋ、４Ｂｋ及び５Ｂｋの製造）
着色粒子１Ｂｋの製造において、表１に記載の製造条件に変更した以外は同様にして、着色粒子２Ｂｋ〜５Ｂｋを各々、製造した。
【０１６９】
（着色粒子６Ｂｋ〜８Ｂｋの製造）
着色粒子１Ｂｋの製造において、表１に記載の製造条件に設定し、且つ、体積平均粒径が３．８μｍになった時点で粒子成長を停止させて、各々、着色粒子６Ｂｋ〜８Ｂｋを製造した。
【０１７０】
（着色粒子９Ｂｋ〜１１Ｂｋの製造）
着色粒子１Ｂｋの製造において、表１に記載の製造条件に設定し、且つ、体積平均粒径が５．５μｍになった時点で粒子成長を停止させ、各々、着色粒子９Ｂｋ〜１１Ｂｋを製造した。
【０１７１】
（着色粒子１２Ｂｋ、１３Ｂｋの製造）
着色粒子１Ｂｋの製造において、体積平均粒径が１．５μｍ、９．３μｍに各々なった時点で、粒子成長を停止させる以外は同様にして、着色粒子１２Ｂｋ、１３Ｂｋを各々製造した。
【０１７２】
（着色粒子１４Ｂｋ、１５Ｂｋの製造）
着色粒子１Ｂｋの製造において、体積平均粒径が５．８μｍ、５．４μｍに各々なった時点で、粒子成長を停止させる以外は同様にして、着色粒子１４Ｂｋ、１５Ｂｋを各々製造した。
【０１７３】
（着色粒子４Ｙの製造）
着色粒子４Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントイエロー１８５を使用した他は同様にして着色粒子を得た。これを「着色粒子４Ｙ」とする。
【０１７４】
（着色粒子４Ｍの製造）
着色粒子４Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントレッド１２２を使用した他は同様にして着色粒子を得た。これを「着色粒子４Ｍ」とする。
【０１７５】
（着色粒子４Ｃの製造）
着色粒子４Ｂｋの製造においてカーボンブラックの代わりにＣ．Ｉ．ピグメントブルー１５：３を使用した他は同様にして着色粒子を得た。これを「着色粒子４Ｃ」とする。
【０１７６】
着色粒子の製造条件を表１、得られた着色粒子の各々の物性を表２に示す。
【０１７７】
【表１】

【０１７８】
【表２】

【０１７９】
（トナー粒子の製造）
得られた着色粒子１Ｂｋ〜１５Ｂｋ、着色粒子１Ｙ、１Ｍ、１Ｃ、４Ｙ、４Ｍ、４Ｃに、各々、疎水性シリカ（数平均一次粒子径＝１２ｎｍ、疎水化度＝６８）を１質量％及び疎水性酸化チタン（数平均一次粒子径＝２０ｎｍ、疎水化度＝６３）添加し、ヘンシェルミキサーにより混合してトナー１Ｂｋ〜１５Ｂｋ、トナー１Ｙ〜１Ｃ、トナー４Ｙ〜４Ｃを得た。
【０１８０】
なお、トナーの形状及び粒径等の物性は表２に示した着色粒子の物性データとと同一であった。
【０１８１】
（現像剤の製造）
上記トナー粒子の各々に対してシリコーン樹脂を被覆した体積平均粒径６０μｍのフェライトキャリアを混合し、トナー濃度が６％の現像剤１Ｂｋ〜１５Ｂｋ、トナー１Ｙ〜１Ｃ、トナー４Ｙ〜４Ｃを各々、製造した。
【０１８２】
《感光体の製造例》
（感光体Ａの製造）
直径６０ｍｍのアルミニウムドラム上にポリアミド樹脂（アミランＣＭ−８０００：東レ社製）１．５質量部をメタノール９０容量部とブタノール１０容量部との混合溶媒中に溶解させた塗布液を浸漬塗布して膜厚０．２３μｍの中間層を形成した。ついで、ポリビニルブチラール（エスレックＢＬ−Ｓ：積水化学社製）０．８質量部をメチルイソプロピルケトン１００質量部中に溶解し、得られた溶液中にチタニルフタロシアニン２質量部を混合、分散してなる塗布液を前記中間層上に浸漬塗布して乾燥後の膜厚が０．２μｍの電荷発生層を形成した。ついで、ポリカーボネートとしてＢＰＺ（粘度平均分子量＝３０，０００）２０質量部と電荷輸送物質（Ｔ−９）１５質量部と１，２−ジクロロエタン１００容量部に溶解してなる塗布液を前記電荷発生層上に浸漬塗布して乾燥後の平均膜厚が４μｍの第一の電荷輸送層（ＣＴＬ）を形成した。
【０１８３】
（感光体Ｂ〜Ｅの製造）
感光体Ａの製造において、表３に示すように電荷輸送層の乾燥後の平均膜厚を変化させた以外は同様にして、感光体Ｂ〜感光体Ｅを各々、製造した。
【０１８４】
得られた感光体Ａ〜Ｅの各々の電荷輸送層の平均膜厚及び、最大膜厚と最小膜厚の差を示す。
【０１８５】
【表３】

【０１８６】
次いで、上記感光体Ａ〜Ｅ、及び現像剤を使用し、コニカ製Ｓｉｔｉｏｓ７０４０（デジタル複写機）を用いて画像形成し、得られた画像を比較評価した。
【０１８７】
《画質評価》
使用する記録材として連量が５５ｋｇの用紙を使用し、縦方向に画像を形成した。また、画像形成条件としては高温高湿環境（３２℃、８５％ＲＨ）にて明朝体／９．６ポイントで「塵」の文字を現像した。得られた「塵」の文字画像を１０世代に渡って複写し、文字として判読可能か否かを１０人のメンバーによる目視判定の平均値により判読できる世代数を判断した。
【０１８８】
本発明において、高画質画像であるとは、少なくとも９世代にわたる複写を行っても、充分に文字として判読可能である場合である。
【０１８９】
《クリーニング性評価》
さらに、ハーフトーン（画素率＝３０％）を１００枚連続で低温低湿環境（１０℃、１０％ＲＨ）にて印字し、クリーニング不良の発生有無を目視で判定し、表４に示すようなランク評価を行った。尚、クリーニング方式はブレードクリーニングを採用した。
【０１９０】
○：問題なし
△：軽微なクリーニング不良発生
×：クリーニング不良発生
得られた結果を表４に示す。
【０１９１】
【表４】

【０１９２】
表４から、本発明の試料は、比較の試料と比べて、高画質であり、且つ、良好なクリーニング性を示すことが明らかである。
【０１９３】
実施例２
《色差の評価》
上記現像剤群及び感光体を使用し、中間転写体を有するカラー複写機を使用して評価を実施した。Ｙ／Ｍ／Ｃ／Ｂｋの現像器を積層型感光体の周囲に配置し、各色をそれぞれ感光体上に現像した後に中間転写体上に各色ずつ転写し、中間転写体上にフルカラー画像を形成した後に画像形成支持体である紙に転写する中間転写体を有する構成のものを使用した。なお、感光体のクリーニングはブレードクリーニング方式を採用した。定着方式としては圧接方式の加熱定着装置を用いた。
【０１９４】
評価は、２５％のフルカラー画素率の原稿を３０℃／８０％ＲＨ環境の高温高湿環境にて１０００枚印字し、１枚目と１０００枚目の画像のクロマの差を色差で評価した。色差は下記手法で評価を行った。
【０１９５】
すなわち、画像各々における二次色（レッド、ブルー、グリーン）のソリッド画像部の色を「Ｍａｃｂｅｔｈ Ｃｏｌｏｒ−Ｅｙｅ７０００」により測定し、ＣＭＣ（２：１）色差式を用いて色差を算出し、下記に記載のように目視でランク評価した。
【０１９６】
５以下 ：色味の変化が検知されない
５を超え８以下：肌色、食品の画像に違和感を生じる程度の僅かな色味の変化がある
８を超え９以下：レッド、グリーン、ブルーにいたるまで、色味の変化が明確に検知される
ＣＭＣ（２：１）色差式で求められた色差が５以下であれば、形成された画像の色味の変化が許容できるレベルである。
【０１９７】
得られた結果を表５に示す。
【０１９８】
【表５】

【０１９９】
表５から、本発明の試料は色差が極めて少ないことが明らかである。
【０２００】
【発明の効果】
本発明により、高画質であり、良好なクリーニング性を示し、且つ、現像初期とランニング後の画像の色差が少ない画像形成方法を提供することが出来た。
【図面の簡単な説明】
【図１】（１）〜（６）は、各々、本発明に用いられる感光体の一態様を示す概略断面図である。
【図２】本発明の画像形成方法に用いられる現像器の概要断面図である。
【図３】本発明に用いられるトナーリサイクル装置の一態様を示す模式図を示す。
【図４】本発明に用いられるカラー電子写真画像形成装置の一例を示す概略断面図。
【符号の説明】
１ 導電性支持体
２ 中間層
３ 電荷輸送層（ＣＴＬ）
４ 電荷発生層（ＣＧＬ）
５ 保護層
６ 感光層
１１ 電子写真感光体ドラム（感光体）
１２ ゴムローラ
１３ スチール製弾性ブレード
１４ スポンジローラ
１５ 撹拌羽根
１６ 非磁性一成分トナー
１７ トナータンク
２１ 現像器
２２ 現像剤搬送スリーブ
２３ 現像剤搬送スクリュー
２５ クリーナー部
２６ リーニング部材（弾性ブレード）
２７ リサイクルトナー回収スクリュー
２８ リサイクルトナー搬送スクリュー
１ａ、１ｂ、１ｃ、１ｄ 静電潜像担持体（電子写真感光体ドラム、感光体ドラム）
２ａ、２ｂ、２ｃ、２ｄ ドラム帯電器
３ａ、３ｂ、３ｃ、３ｄ 現像器
４ａ、４ｂ、４ｃ、４ｄ 転写帯電器
４１ａ、４１ｂ、４１ｃ、４１ｄ 転写押圧部材
５ａ、５ｂ、５ｃ、５ｄ 感光体クリーニング部
１０ 定着部（定着器）
１６ａ 先端縁部
１７ａ レーザビーム露光装置
２１ａ、２１ｂ、２１ｃ、２１ｄ 除電露光ランプ
２２ａ、２２ｂ、２２ｃ、２２ｄ 電位センサ
Ｐａ、Ｐｂ、Ｐｃ、Ｐｄ 画像形成部
７１、７２ 加熱ローラ
７３、７４ 耐熱クリーニング部材
７５、７６ ヒータ
７７ オイル塗布ローラ
７８ オイル溜め
７９ サーミスタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method for developing a latent image formed on an electrostatic latent image carrier using a developer containing toner for developing an electrostatic image.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electrostatic latent image developing method mainly using an electrophotographic method is used for an image forming apparatus that is used in a copying machine, a printer, and the like and that requires a high-speed and high-quality image. The reason for this is that, in addition to the above-mentioned advantages, the image quality can be stably obtained even when used for a long period of time, and color image formation can be supported.
[0003]
Many electrostatic latent image development methods (most of which are electrophotographic methods, and may be referred to as electrophotographic methods hereinafter) have been developed depending on the purpose of use, and each has its own characteristics. Utilizing these features, the most appropriate one is selected and used for each application. Among them, what is commonly required is the pursuit of higher image quality and durability, resource saving, pollution-free and cost reduction.
[0004]
Among the electrostatic latent image development methods, the non-magnetic one-component development method does not require a toner density adjustment mechanism, and is preferred as a simple method and can be used in image forming apparatuses such as relatively small printers and facsimiles. Many.
[0005]
On the other hand, the magnetic two-component development method is a method in which a carrier and a toner are mixed and tends to be a little larger, but because of its charge-separating function separation structure, it can stably form an image and is currently most widely used. ing.
[0006]
In any of these, it is effective to reduce the toner particle size in order to improve the image quality. Small particle size toners are becoming increasingly important in order to form high-quality images in the recent digital trend. Further, from the viewpoints of resource saving, pollution-free, and image formation cost reduction, a toner recycling system that reuses toner collected by cleaning from the photoreceptor is useful.
[0007]
However, in the conventional image forming method described above, when a toner having a small particle size is used, it is easily affected by stress in the developing device, and in non-magnetic one-component development, a thin layer is formed in the toner transport system. Stress during cleaning in the toner recycling system and stress such as shear stress in the transport system, contamination of the carrier with the two-component developer, etc. An image defect has occurred and its stabilization has not been achieved.
[0008]
Further, it has been pointed out that when a toner having a small particle size is used, the cleaning property is liable to deteriorate, and when a color toner is used, the color difference between the image at the initial stage of development and after running tends to be large. Yes.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming method that has high image quality, exhibits good cleaning properties, and has little color difference between an image at the initial stage of development and that after running.
[0010]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following item 1.
[0011]
  1. A latent image formed on an electrostatic latent image carrier having a charge generation layer and a charge transport layer on a conductive support is developed with a developer containing a toner for developing an electrostatic image, and visualized. In an image forming method having a step of transferring to an image support,
  50% volume particle size (Dv50) of at least one tonerIs 2 μm to 8 μm, and the toner has a 50% volume particle diameter (Dv50).And the 50% number particle size (Dp50) ratio (Dv50 / Dp50) is 1.0 to 1.15, the cumulative 75% volume particle size (Dv75) from the larger volume particle size of the toner, The ratio (Dv75 / Dp75) of the cumulative 75% number particle size (Dp75) from the larger number particle size is 1.0 to 1.20, and the toner is 0.7 × (Dp50) or less in the total toner. The number is 10% or lessTheThe average film thickness of the charge transport layer is 5 μm to 15 μmIn addition, the toner is manufactured through a process of salting out / fusing resin particles obtained by polymerizing a polymerizable monomer.An image forming method.
[0012]
Hereinafter, the present invention will be described in detail.
The electrostatic image developing toner according to the image forming method of the present invention will be described.
[0013]
The inventors of the present invention have a problem with a conventionally known image forming method using a toner having a reduced particle size (in the present invention, a toner particle having a particle size of 2 μm to 10 μm is referred to as a small particle size toner). As a result of intensive studies, it was found that the toner having a small particle size is likely to have a difference in the adhesion amount and transferability between the particles, and that it is easily affected by the charge on the photoreceptor.
[0014]
Further, it has been found that in the small particle size toner, the difference in developability and the difference in the amount of adhesion for each toner increase as the particle size decreases. The mechanism of this phenomenon itself is not clear, but in the case of toner with a large particle size, the difference in adhesion to the photoconductor for each toner does not increase, but as the particle size decreases, the original photoconductor possessed by the toner itself. It was estimated that the adhesion force of the particles increased and the difference between particles increased.
[0015]
Therefore, as a result of the study, it was found that by reducing the film thickness of the photoconductor, the difference in fluctuation of the adhesion force to the photoconductor can be reduced, and furthermore, the fluctuation of the surface potential of the photoconductor can also be suppressed. It has also been found that uniform transferability and developability can be achieved with the toner prepared.
[0016]
The thin film photoreceptor as described above is known to have high reproducibility of latent image dots formed by digital exposure. However, when used with a small particle size toner, the resolution is too high, so that the positional deviation of the beam during exposure is low. There was a problem that appeared as an image. Specifically, what should originally appear as a thin straight line tends to form a rope-like pattern at the edge of the line, and as a result, the density reproducibility of the image portion expressing the halftone by densely consolidating the lines is reduced. There was a problem to do. In particular, when a color image is formed, there is a problem in that the reproducibility of a secondary color that expresses colors is lowered and a color difference is generated.
[0017]
In order to improve this, the present inventors have focused on the photoreceptor film thickness and toner particle size distribution, and while having high resolution, the photoreceptor film thickness and toner particle size distribution that absorbs the irregularities caused by the beam shift of the latent image. As a result, the present inventors have found a suitable range of the present invention and have completed the present invention.
[0018]
Specifically, the present inventors have focused on the 50% particle size, which is the median value of the toner particle size for all toners, rather than simply reducing the abundance of small particle size components that increase adhesion. In analyzing the small particle size component deviating from the particle size, the cumulative particle size of 75% frequency from the large particle size side of the toner to the large particle size side of the toner, respectively. As a result of various studies focusing on the above, the ratio (Dv50 / Dp50) of the 50% volume particle size (Dv50) and the 50% number particle size (Dp50) of at least one toner as described in claim 1. ) Is 1.0 to 1.15, a cumulative 75% volume particle size (Dv75) from the toner having a larger volume particle size, and a cumulative 75% number particle size of the toner from the larger number particle size. (Dp75) ratio (Dv75 / Dp75) is 1.0 to 1.20, By using an image forming method in which the toner number of 0.7 × (Dp50) or less in the toner is 10% by number or less, and the average film thickness of the charge transport layer is 5 μm to 15 μm, The present invention has been completed.
[0019]
The electrostatic image developing toner (hereinafter also simply referred to as toner) according to the present invention will be described.
[0020]
First, the volume particle size, the number particle size, and the ratio between the volume particle size and the number particle size of the toner according to the present invention will be described.
[0021]
From the viewpoint of obtaining the effects described in the present invention, the toner according to the present invention is preferably monodispersed as a particle size distribution, and at least one toner has 50% volume particle size (Dv50) and 50% number particles. The ratio (Dv50 / Dp50) of the diameter (Dp50) needs to be 1.0 to 1.15, but is preferably 1.0 to 1.13.
[0022]
In order to suppress the fluctuation range of transferability and developability, the at least one kind of toner has a cumulative 75% volume particle size (Dv75) and 75% number particle size (Dp75) from the larger toner. The ratio (Dv75 / Dp75) is required to be 1.0 to 1.20, and preferably 1.1 to 1.19. Further, the number of toner particles of 0.7 × (Dp50) or less in all toners needs to be 10% by number or less, and preferably 5% by number to 9% by number.
[0023]
The toner according to the present invention has a 50% volume particle size (Dv50) of preferably 2 μm to 8 μm, more preferably 3 μm to 7 μm. The 50% number particle size (Dp50) of the toner according to the present invention is preferably 2 μm to 7.5 μm, and more preferably 2.5 μm to 7 μm. By setting it as this range, the effect of this invention can be exhibited more notably.
[0024]
Further, when a plurality of toners are used in the present invention, all the toners satisfy the above-described requirements, that is, the ratio of 50% volume particle size (Dv50) to 50% number particle size (Dp50) (Dv50 / Dp50). Is 1.0 to 1.15, and the cumulative 75% volume particle diameter (Dv75) of the toner from the larger volume particle diameter and the cumulative 75% number of the toner from the larger particle diameter of the toner. The ratio (Dv75 / Dp75) of the particle diameter (Dp75) is 1.0 to 1.20, and the number of toners of 0.7 × (Dp50) or less in all toners satisfies the requirement of 10% by number or less. preferable.
[0025]
Here, the cumulative 75% volume particle diameter (Dv75) or the cumulative 75% number particle diameter (Dp75) from the larger one is the sum of the frequencies from the larger particle diameter and the sum of the total volume or the sum of the numbers. On the other hand, each is represented by a volume particle size or a number particle size of a particle size distribution portion showing 75%.
[0026]
In the present invention, 50% volume particle size (Dv50), 50% number particle size (Dp50), cumulative 75% volume particle size (Dv75), cumulative 75% number particle size (Dp75) and the like are Coulter Counter TA-II type Alternatively, it can be measured with a Coulter Multisizer (manufactured by Coulter).
[0027]
The photoreceptor has an electrostatic latent image carrier in which at least a charge generation layer and a charge transport layer are laminated on a conductive support. From the viewpoint of reducing the difference in dielectric constant on the photoreceptor to stabilize the developability and transferability of the toner and obtaining the effects described in the present invention, the film thickness of the charge transport layer is 5 μm to 15 μm on average. However, it is preferably 6 μm to 13 μm. Here, the film thickness of the charge transport layer can be measured using an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO). As the charge transport layer thickness, the thickness of the photosensitive layer is measured at 10 random locations, and the average value obtained from the measurement is adopted as the thickness value.
[0028]
Further, it is preferable that the difference between the maximum film thickness and the minimum film thickness is 2 μm or less as the fluctuation range of the film thickness of the photoreceptor.
[0029]
The components of the toner for developing an electrostatic image according to the present invention, the components of the binder resin that is a component of the toner, and the production thereof will be described.
[0030]
The toner according to the present invention contains at least a colorant, a binder resin, and the like. The toner may be manufactured through a pulverization / classification process, and is obtained by polymerizing a polymerizable monomer as shown below. The toner particles may be produced by a so-called polymerization method in which a toner is produced using the resin particles. When a toner is produced using a polymerization method, a production method having a step of salting out / fusing resin particles is particularly preferable.
[0031]
As the polymerizable monomer used in the polymerization method, a radical polymerizable monomer can be used as a constituent component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.
[0032]
(1) Radical polymerizable monomer
The radical polymerizable monomer component is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.
[0033]
Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers And halogenated olefin monomers.
[0034]
Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.
[0035]
(Meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.
[0036]
Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.
[0037]
Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.
[0038]
Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.
[0039]
Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.
[0040]
Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.
[0041]
(2) Cross-linking agent
As the crosslinking agent, a radical polymerizable crosslinking agent may be added in order to improve the properties of the toner. Examples of the radically polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.
[0042]
(3) Radical polymerizable monomer having an acidic group or radical polymerizable monomer having a basic group
Examples of the radical polymerizable monomer having an acidic group or the radical polymerizable monomer having a basic group include a polymerizable monomer having a carboxyl group, a polymerizable monomer having a sulfonic acid group, Examples include amine-based polymerizable monomers such as secondary amines, secondary amines, tertiary amines, and quaternary ammonium salts.
[0043]
Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester and the like.
[0044]
Examples of the polymerizable monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like.
[0045]
These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.
[0046]
Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, N-diary Ammonium chloride, N, N-diallyl-ethyl ammonium chloride, and the like.
[0047]
As the radical polymerizable monomer used in the present invention, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group is used in an amount of 0.1 to 15% by mass based on the whole monomer. The radical polymerizable crosslinking agent is preferably used in the range of 0.1 to 10% by mass with respect to the total radical polymerizable monomer, although it depends on its properties.
[0048]
[Chain transfer agent]
For the purpose of adjusting the molecular weight, a commonly used chain transfer agent can be used. The chain transfer agent is not particularly limited, and for example, octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionic acid ester, carbon tetrabromide and styrene dimer are used.
[0049]
(Polymerization initiator)
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), peroxides Compounds and the like.
[0050]
Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature is lowered, and the polymerization time can be further shortened.
[0051]
The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, but for example, a range of 50 ° C. to 90 ° C. is used. However, it is possible to perform polymerization at room temperature or higher by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).
[0052]
[Surfactant]
In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.
[0053]
Examples of the ionic surfactant include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).
[0054]
Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.
[0055]
In the present invention, these are mainly used as an emulsifier at the time of emulsion polymerization, but may be used for other processes or purposes.
[0056]
[Colorant]
Examples of the colorant include inorganic pigments, organic pigments, and dyes.
[0057]
A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.
[0058]
Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
[0059]
These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0060]
When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.
[0061]
Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.
[0062]
Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
[0063]
Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, and the like.
[0064]
Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
[0065]
As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used.
[0066]
These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0067]
The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.
[0068]
The toner according to the present invention may be used in combination with a release agent. For example, low molecular weight polyolefin waxes such as polypropylene and polyethylene, paraffin wax, Fischer-Tropsch wax, ester wax and the like can be used as the release agent. Moreover, in this invention, the ester wax shown by following General formula (1) can be used preferably.
[0069]
General formula (1)
R₁-(OCO-R₂)_n
In the formula, n represents an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.
[0070]
R₁, R₂Represents a hydrocarbon group which may have a substituent.
R₁: Carbon number = 1-40, preferably 1-20, more preferably 2-5
R₂: Carbon number = 1-40, preferably 13-29, more preferably 12-25
Specific examples of the crystalline compound having an ester group according to the present invention are shown below, but the present invention is not limited thereto.
[0071]
[Chemical 1]

[0072]
[Chemical 2]

[0073]
These ester waxes are contained in resin particles and have a function of imparting good fixability (adhesiveness to an image support) to a toner obtained by fusing resin particles.
[0074]
The addition amount of the release agent used in the present invention is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass, and further preferably 3% by mass to 15% by mass with respect to the whole toner. Further, the toner of the present invention is an ester compound as described above as a release agent in resin particles in which the release agent dissolved in the polymerizable monomer is dispersed in water and polymerized. A toner prepared by a step of forming particles encapsulating and salting out and fusing together with colorant particles is preferable.
[0075]
The toner according to the present invention may contain materials capable of imparting various functions as toner materials in addition to the colorant and the release agent. Specific examples include charge control agents. These components can be added simultaneously with the resin particles and the colorant particles in the salting out / fusion step described above, and can be added by various methods such as a method included in the toner and a method of adding to the resin particles themselves.
[0076]
Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
[0077]
The external additive used for the toner according to the present invention will be described.
The toner according to the present invention can be used by adding a so-called external additive for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, but various inorganic fine particles, organic fine particles and lubricants can be used.
[0078]
A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titanium, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic. Specifically, as silica fine particles, for example, commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H manufactured by Hoechst -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.
[0079]
Examples of the titanium fine particles include commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.
[0080]
Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.
[0081]
As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.
[0082]
Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.
[0083]
The amount of these external additives added is preferably 0.1 to 5% by mass with respect to the toner.
Examples of the method for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.
[0084]
A method for producing an electrostatic charge image developing toner according to the present invention will be described.
"Manufacturing process"
In the toner of the present invention, a polymerizable monomer or a polymerizable monomer solution as described above in which a release agent is dissolved is dispersed in an aqueous medium, and then resin particles encapsulating the release agent are obtained by a polymerization method. A step of adjusting, a step of fusing resin particles in an aqueous medium using the resin particle dispersion, a washing step of filtering the obtained particles from an aqueous medium to remove a surfactant, and the like. It is preferable to produce by a polymerization method comprising a drying step and an external additive addition step of adding an external additive to particles obtained by drying. Here, the resin particles may be colored particles. In addition, non-colored particles can also be used as resin particles. In this case, colored particles are formed by adding a colorant particle dispersion or the like to the resin particle dispersion and then fusing it in an aqueous medium. Can do.
[0085]
In particular, the method of fusing is preferably a method of salting out / fusing using resin particles produced by the polymerization step. When non-colored resin particles are used, the resin particles and the colorant particles can be salted out / fused in an aqueous medium.
[0086]
In addition to the colorant and the release agent, a charge control agent that is a component of the toner can be added as particles in this step.
[0087]
In addition, an aqueous medium here consists of water as a main component, and shows content whose water content is 50 mass% or more. Examples of substances other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Alcohol organic solvents such as methanol, ethanol, isopropanol, and butanol, which are preferably organic solvents that do not dissolve the resin, are particularly preferable.
[0088]
As a preferable polymerization method in the present invention, a monomer solution in which a release agent is dissolved in a monomer is dispersed in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved, and dispersed in oil droplets by mechanical energy. And a method of radical polymerization by adding a water-soluble polymerization initiator. In this case, an oil-soluble polymerization initiator may be added to the monomer.
[0089]
The disperser for performing the oil droplet dispersion is not particularly limited, and examples thereof include CLEARMIX, ultrasonic disperser, mechanical homogenizer, manton gourin, and pressure homogenizer.
[0090]
The colorant itself may be used after surface modification. In the surface modification method of the colorant, the colorant is dispersed in a solvent, and after the surface modifier is added therein, the temperature is raised and the reaction is performed. After completion of the reaction, the mixture is filtered, washed with the same solvent, repeatedly filtered and dried to obtain a pigment treated with a surface modifier.
[0091]
There is a method in which the colorant particles are prepared by dispersing a colorant in an aqueous medium. This dispersion is preferably performed in a state where the surfactant concentration in water is equal to or higher than the critical micelle concentration (CMC).
[0092]
The disperser at the time of pigment dispersion is not particularly limited, but preferably a medium such as CLEARMIX, ultrasonic disperser, mechanical homogenizer, pressure disperser such as Manton Gorin or pressure homogenizer, sand grinder, Getzmann mill, diamond fine mill, etc. Type disperser.
[0093]
As the surfactant used here, the aforementioned surfactants can be used.
In the salting-out / fusion process, a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like is added as a flocculant having a critical coagulation concentration or higher in water in which resin particles and colorant particles are present. Next, it is a step of performing fusion at the same time as salting-out proceeds by heating the resin particles to a temperature higher than the glass transition point.
[0094]
Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used. Examples of the salt include chlorine salt, bromine salt, iodine salt, carbonate salt, sulfate salt and the like.
[0095]
The method for achieving the toner particle size distribution is not particularly limited, but for example, a method such as control by classification or the like, temperature or time at the time of association, and control of a stopping method for terminating the association are used. can do.
[0096]
As a particularly preferable production method, a method of controlling the association time in water, the association temperature, the stopping speed, and the like can be mentioned. That is, in the case of performing salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible. The reason for this is not clear, but there are problems that the aggregation state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. appear. The temperature at which the salting-out agent is added is not particularly limited.
[0097]
In the present invention, it is preferable to use a method in which the dispersion of the resin particles is heated as quickly as possible and heated to the glass transition temperature or more of the resin particles. The time until this temperature rise is less than 30 minutes, preferably less than 10 minutes. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 1 ° C./min or more. The upper limit is not particularly clear, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of salting out / fusion. As a particularly preferred embodiment, there can be mentioned a method in which salting-out / fusion is continued even when the glass transition temperature is reached. By adopting this method, the fusion can be effectively advanced as the particles grow, and the durability as a final toner can be improved.
[0098]
Furthermore, it is possible to control the particle size in particular by salting out / fusion using a divalent metal salt at the time of association. Although the reason for this is not clear, the use of a divalent metal salt increases the repulsive force during salting out, making it possible to effectively suppress the dispersibility of the surfactant, resulting in an exile distribution. It is estimated that it became possible to control.
[0099]
Moreover, it is preferable to add a monovalent metal salt and water in order to stop the salting out / fusion. By adding this, salting out can be stopped, and as a result, the presence of large particle size components and small particle size components can be suppressed.
[0100]
For polymerized toners that associate or fuse resin particles in an aqueous medium, by controlling the flow and temperature distribution of the medium in the reaction vessel in the fusing step, the heating temperature is further increased in the shape control step after fusing. The shape distribution and shape of the entire toner can be arbitrarily changed by controlling the number of rotations of stirring and time.
[0101]
That is, in the polymerization method toner that associates or fuses the resin particles, the flow in the reaction apparatus is made into a laminar flow, and the agitation step and the agitation tank that can make the internal temperature distribution uniform are used. By controlling the temperature, the number of rotations, and the time in the shape control step, the toner having the shape factor and uniform shape distribution of the present invention can be formed. The reason for this is that if the laminar flow is fused in a place where the laminar flow is formed, strong stress is not applied to the particles (aggregation or agglomerated particles) in which aggregation and fusion proceed, and in laminar flow where the flow is accelerated As a result of the uniform temperature distribution in the stirring tank, the shape distribution of the fused particles is estimated to be uniform. Further, the fused particles gradually become spherical by heating and stirring in the subsequent shape control step, and the shape of the toner particles can be arbitrarily controlled.
[0102]
In order to control the toner of the present invention to a predetermined shape, it is preferable that salting-out and fusion are simultaneously performed. In the method of heating after forming the agglomerated particles, the shape tends to be distributed, and the generation of fine particles cannot be suppressed. That is, since the aggregated particles are heated while being stirred in the aqueous medium, it is presumed that the aggregated particles are repartitioned and a component having a small particle size is likely to be generated.
[0103]
The developer used in the present invention will be described.
When used as a two-component developer by mixing with a carrier, as the carrier magnetic particles, conventionally known materials such as metals such as iron, ferrite, magnetite, and alloys of these metals with metals such as aluminum and lead Can be used. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.
[0104]
The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
[0105]
The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.
[0106]
An electrostatic latent image carrier (also referred to as a photoreceptor) according to the present invention will be described.
As the photoreceptor according to the present invention, an organic photoreceptor is preferably used. A preferable configuration of the organic photoreceptor will be described with reference to FIGS.
[0107]
Here, FIGS. 1 (1) to 1 (6) are schematic cross-sectional views each showing an embodiment of the photoreceptor used in the present invention.
[0108]
FIG. 1 (1) is a photoreceptor having a single-layered photosensitive layer 6 containing both a charge generation material (CGM) and a charge transport material (CTM) via an intermediate layer 2 on a conductive support 1. FIG. 1 (2) shows a charge generation containing a charge transport layer (CTL) 3 containing a charge transport material as a main component and a charge generation material (CGM) as a main component via an intermediate layer 2 on a conductive support 1. 1 is a photosensitive member having a photosensitive layer 6 formed by laminating layers (CGL) 4 in that order. FIG. 1 (3) mainly shows a charge generating material (CGM) on a conductive support 1 through an intermediate layer 2. It is a photoreceptor having a photosensitive layer 6 in which a charge generation layer (CGL) 4 containing components and a charge transport layer (CTL) 3 containing a charge transport material as a main component are laminated in that order. FIGS. 1 (4), (5), and (6) show structures in which a protective layer 5 is laminated on the photosensitive layer 6 in FIGS. 1 (1), (2), and (3), respectively.
[0109]
These cross-sectional views shown in FIGS. 1 (1) to 1 (6) show a typical configuration, and are not limited to this configuration. Further, the intermediate layer 2 shown in these configurations may be provided as necessary, or may not be provided. Further, semiconductive fine particles such as titanium oxide may be added to the intermediate layer.
[0110]
Silica or organic fine particles can also be added to the protective layer 5. Furthermore, you may add CTM in a protective layer.
[0111]
As a charge generating material (CGM) used in the photoreceptor shown in FIGS. 1 (1) to (6). For example, phthalocyanine pigments, polycyclic quinone pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes, triphenylmethane dyes, styryl dyes, etc. These can be used alone or in combination to form a layer with an appropriate binder resin.
[0112]
A particularly preferred CGM is a phthalocyanine pigment, and in particular a titanyl phthalocyanine type pigment having a Bragg angle 2θ with respect to the Cu-Kα line having a maximum peak at 27.2 °, for example, a bisbenzo having the maximum peak at 22.4 ° Examples include imidazole perylene.
[0113]
As the binder constituting the charge transport layer, a known resin can be used, and preferred resins include a formal resin, a butyral resin, a silicon resin, a silicon-modified butyral resin, and a phenoxy resin. The ratio of the binder resin and CGM is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the CGL layer is preferably 0.01 to 2 μm.
[0114]
Examples of the charge transport material (CTM) contained in the photosensitive layer 6 include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, triazole derivatives, imidazole derivatives, imidazoline derivatives, imidazolone derivatives, bisimidazolidine derivatives, and styryl derivatives. , Hydrazone derivatives, benzidine derivatives, pyrazoline derivatives, stilbene derivatives, amine derivatives, oxazolone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, poly-N- Examples thereof include carbazole, poly-1-vinylpyrene, poly-9-vinylanthracene and the like. These CTMs can usually be layered together with a binder.
[0115]
Among these, a particularly preferred CTM used in the present invention includes a triphenylamine styryl compound represented by the following general formula (3).
[0116]
[Chemical 3]

[0117]
In general formula (3), R₁~ R_ThreeEach represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group. l, m, and n represent an integer of 0 to 3. Ar represents a hydrogen atom or an aryl group. The aryl group may be unsubstituted or may have a substituent, and examples of the substituent include a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group. Of the aryl groups, a phenyl group is particularly preferred.
[0118]
Specific examples of the triphenylamine styryl compound represented by the general formula (3) are shown below, but the present invention is not limited thereto.
[0119]
[Formula 4]

[0120]
[Chemical formula 5]

[0121]
[Chemical 6]

[0122]
[Chemical 7]

[0123]
[Chemical 8]

[0124]
[Chemical 9]

[0125]
Examples of the binder contained in these charge transport layers include polycarbonate resin, polyester, styrene resin, acrylic resin, vinyl chloride resin, polyvinyl butyral, polyvinyl acetal, styrene-butadiene resin, urethane resin, silicone resin, phenol resin, and the like. As a particularly preferred binder, a polycarbonate resin can be exemplified.
[0126]
The CTL is formed by dissolving the CTM in the above-described organic solvent and applying and drying the binder resin. The ratio of CTM to binder resin in CTL is preferably 3: 1 to 1: 3 by mass ratio.
[0127]
When a plurality of CTLs are formed, it is preferable that the binder resin contained in the CTL formed in the uppermost layer has a high molecular weight. This is because the mechanical strength can be improved by adopting this configuration.
[0128]
In particular, the molecular weight of the polycarbonate resin as the binder resin used for the uppermost CTL is preferably 50,000 or more in terms of viscosity average molecular weight, and more preferably 100,000 to 500,000. Moreover, it is preferable that the viscosity average molecular weight of the polycarbonate resin contained in CTL formed in the lower layer is smaller than that of the uppermost layer. The preferred molecular weight range in this case is less than 50,000, preferably 20,000 to 40,000. With this configuration, mechanical polishing resistance can be improved, and film thickness fluctuations on the thin film photoreceptor can be minimized.
[0129]
As a conductive support for constituting the photoreceptor,
(1) Conductive metals such as aluminum and stainless steel,
(2) The surface of an insulating substrate such as paper or plastic film coated with a conductive metal such as aluminum, palladium or gold by lamination or vapor deposition,
(3) Examples include those in which a conductive polymer, indium oxide, tin oxide or other conductive compound layer is formed on the surface of an insulating substrate such as paper or plastic film by coating or vapor deposition.
[0130]
Examples of the coating method for producing the photoreceptor according to the present invention include dip coating, spray coating described in JP-A-3-90250 and JP-A-3-269238, and JP-A-58-189061. There are coating methods such as circular amount regulation type coating. Among these, the circular amount regulation type coating method is preferably used as a method for producing a laminated structure because the upper layer can be applied without dissolving the lower layer.
[0131]
The image forming method of the present invention will be described.
The image forming method of the present invention comprises a latent image forming step for forming a latent image on an electrostatic latent image carrier, a developing step for developing the latent image with toner, and a latent image on the latent image carrier. 2. An image forming method comprising at least a transfer step of transferring a formed toner image onto a transfer member and a fixing step of fixing the toner image onto the transfer member, wherein the electrostatic charge according to claim 1 is used as the toner. Image developing toner is used.
[0132]
In the image forming method of the present invention, a method of developing a latent image by supplying a thin non-magnetic toner to the surface of the electrostatic latent image forming body is preferable.
[0133]
An image forming apparatus according to an image forming method of the present invention includes a toner conveying member, a toner layer regulating member, and a toner replenishing auxiliary member, and the toner replenishing auxiliary member and the toner conveying member, and the toner layer regulating member and the toner conveying member. It is preferable that each contact | abut.
[0134]
The toner conveying member supplies non-magnetic toner to an electrostatic latent image forming body such as an electrophotographic photosensitive member, and as such a member, a sufficient developing area is secured in a state of being in contact with the electrostatic latent image forming body. Therefore, a member having elasticity is preferable.
[0135]
In the present invention, the toner conveying member is a roller made of urethane rubber or silicone rubber, or a sponge roller inside a conductive endless belt-like member (specifically, nickel or PET base surface coated with a conductive material). Those encapsulating are preferably used.
[0136]
The toner layer regulating member has a function of uniformly applying toner to the toner conveying member and imparting frictional charging, and specifically, an elastic body such as urethane rubber or a metal plate is used. The toner layer regulating member is brought into contact with the toner conveying member to form a thin toner layer on the toner conveying member. The toner thin layer is a layer formed in the developing region in a state where the toner has a maximum of 10 layers, preferably 5 layers or less.
[0137]
In the present invention, the toner layer regulating member has a pressure of 100 mN / cm to 5 N / cm with respect to the toner conveying member from the viewpoint of preventing unevenness of conveyance due to uniform toner conveyance and white streaks on the image. It is preferable that the contact is made at 200 mN / cm to 4 N / cm.
[0138]
The toner replenishing auxiliary member is a unit for stably supplying toner to the toner conveying member. As this, a water wheel-like roller with a stirring blade or a sponge-like roller can be used. In the present invention, from the viewpoint of stabilizing toner supply and preventing the occurrence of streak-like image defects, the toner replenishing member preferably has a diameter in the range of 0.2 to 1.5 times that of the toner conveying member. .
[0139]
Next, an embodiment of a developing device (developing device) used in the image forming method of the present invention will be specifically described with reference to FIG.
[0140]
FIG. 2 is a schematic sectional view of a developing device used in the image forming method of the present invention.
In FIG. 2, the non-magnetic one-component toner 16 built in the toner tank 17 is forcibly conveyed and supplied onto a sponge roller 14 as a toner replenishing auxiliary member by a stirring blade 15 as a toner replenishing auxiliary member. The toner incorporated on the sponge roller 14 is conveyed onto the rubber roller 12 as a toner conveying member by the rotation of the sponge roller 14 in the direction of the arrow, and is electrostatically and physically attracted to the surface by friction with the rubber roller 12. Is done. On the other hand, the toner adhering to the rubber roller 12 is uniformly thinned and frictionally charged by the rotation of the rubber roller 12 in the direction of the arrow and the steel elastic blade 13 as a toner layer thickness regulating member.
[0141]
The toner thin layer thus formed on the rubber roller 12 develops the latent image by contacting or approaching the surface of the electrophotographic photosensitive drum (photosensitive member) 11 as an electrostatic latent image carrier. The developing device used in the image forming method of the present invention is not limited to FIG.
[0142]
As the fixing method used in the present invention, a so-called contact heating method is a preferable fixing method. In particular, examples of the contact heating method include a heat pressure fixing method, a heat roller fixing method, and a pressure heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body.
[0143]
In the hot roll fixing method, in many cases, an upper roller having a heat source inside a metal cylinder composed of iron, aluminum or the like whose surface is coated with tetrafluoroethylene or polytetrafluoroethylene-perfluoroalkoxy vinyl ether copolymers, etc. And a lower roller made of silicone rubber or the like. A typical example of the heat source is one that has a linear heater and heats the surface temperature of the upper roller to about 120 to 200 ° C. In the fixing unit, pressure is applied between the upper roller and the lower roller to deform the lower roller to form a so-called nip. The nip width is 1 to 10 mm, preferably 1.5 to 7 mm. The fixing linear velocity is preferably 40 mm / sec to 600 mm / sec. If the nip is narrow, heat cannot be uniformly applied to the toner, and uneven fixing occurs. On the other hand, when the nip width is wide, the melting of the resin is promoted, and the problem of excessive fixing offset occurs.
[0144]
The image forming apparatus used in the present invention is preferably provided with a fixing cleaning mechanism. As the fixing cleaning mechanism, a method in which silicone oil is supplied to the upper roller or film for fixing, or a method of cleaning with a pad, roller, web or the like impregnated with silicone oil can be used. In the present invention, a method of fixing by a rotating pressure member including a heating element fixedly arranged can be preferably used.
[0145]
This fixing method is a method in which pressure heating and fixing are performed by a fixedly arranged heating body and a pressure member that opposes the heating body and presses the recording material in close contact with the heating body through a film. The fixing device used in the heating unit has a heating capacity smaller than that of a conventional heating roller, and has a line-shaped heating portion in a direction perpendicular to the passing direction of the recording material. The temperature is preferably adjusted to 300 ° C.
[0146]
The image forming apparatus used in the image forming method of the present invention preferably has a toner recycling mechanism.
[0147]
Hereinafter, an embodiment of the toner recycling apparatus will be described with reference to FIG.
In the figure, 21 is a developing device, 22 is a developer conveying sleeve, 23 is a developer conveying screw, 11 is an electrophotographic photosensitive drum (photosensitive member), 25 is a cleaner unit, 26 is a cleaning member (elastic blade), and 27 is A recycled toner collecting screw 28 is a recycled toner conveying screw.
[0148]
In FIG. 3, the untransferred toner scraped off by the cleaning member 26 is conveyed from the cleaner unit by the recycled toner collecting screw 27 and is supplied again to the developing device 21 by the recycled toner conveying screw 28.
[0149]
The toner recycling mechanism used in the present invention is not limited to FIG.
In addition to the above, the toner recycling system includes a system in which the toner developed on the photoconductor and remaining on the photoconductor without being transferred to paper or the like is collected by a blade or the like and conveyed to a developing device. A method may be used in which the toner is directly returned to the developing unit, and the replenished toner and the recycled and collected toner are once mixed in advance in an intermediate tank and then supplied to the developing unit.
[0150]
An example of the image forming apparatus used in the present invention is shown using a color electrophotographic image forming apparatus as shown in FIG.
[0151]
FIG. 4 is a schematic configuration diagram showing an example of a color electrophotographic image forming apparatus used in the present invention.
[0152]
In the main body of the color electrophotographic image forming apparatus, first, second, third and fourth image forming portions Pa, Pb, Pc and Pd are installed in parallel. Each image forming unit has the same configuration, and forms visible images (toner images) of different colors.
[0153]
The image forming portions Pa, Pb, Pc, and Pd include dedicated electrostatic latent image carriers (electrophotographic photosensitive drums) 1a, 1b, 1c, and 1d, respectively. The images on the electrophotographic photosensitive drums 1a, 1b, 1c, and 1d formed by the image forming units Pa, Pb, Pc, and Pd are adjacent to the image forming units. Then, the image is transferred onto a recording material (transfer material, image support) carried and conveyed on the recording material carrier 18 that moves. Further, the image on the recording material is fixed by heating and pressurizing by the fixing unit (fixing device) 10, and the recording material is discharged to the tray 61.
[0154]
Next, the latent image forming unit in each image forming unit will be described. Disposed on the outer periphery of each of the photosensitive drums 1a, 1b, 1c, and 1d are static elimination exposure lamps 21a, 21b, 21c, and 21d, drum chargers 2a, 2b, 2c, and 2d, a laser beam exposure device 17a as an image exposure unit, and a potential Sensors 22a, 22b, 22c, and 22d are provided. The photosensitive drums 1a, 1b, 1c, and 1d that have been neutralized by the neutralizing exposure lamps 21a, 21b, 21c, and 21d are uniformly charged by the drum chargers 2a, 2b, 2c, and 2d, and then the laser beam exposure device 17a. As a result of the exposure, a color-separated electrostatic latent image corresponding to the image signal is formed on the photosensitive drums 1a, 1b, 1c, and 1d. In the image forming apparatus of the present invention, as the image exposure means, in addition to the laser beam exposure apparatus 17a described above, a light quantity level other than OFF in a basic image unit (pixel) such as an LED array exposure apparatus is used. Well-known multi-value exposure means that can irradiate can be suitably employed.
[0155]
The electrostatic latent image on the photosensitive drum is developed by a developing unit to become a visible image. That is, the developing means includes developing devices 3a, 3b, 3c, and 3d filled with a predetermined amount of cyan, magenta, yellow, and black developers, respectively, and the photosensitive drums 1a, 1b, and 1c. The electrostatic latent image formed on 1d is developed into a visible image (toner image).
[0156]
Next, the transfer part will be described. The recording material held in the recording material cassette 60 is fed to the recording material carrier 18 through a registration roller.
[0157]
When the recording material carrier 18 starts to rotate, the recording material is conveyed from the registration roller onto the recording material carrier 18. At this time, the image writing signal is turned ON, and an image is formed on the first electrophotographic photosensitive drum 1a at an appropriate timing.
[0158]
A transfer charger 4a and a transfer pressing member 41a are provided below the first electrophotographic photosensitive drum 1a, and the transfer pressing member 41a applies a uniform pressing force toward the photosensitive drum, and Then, the transfer charger 4a applies an electric field to transfer the toner image on the photosensitive drum 1a onto the recording material. At this time, the recording material is held on the recording material carrier 18 by an electrostatic attraction force, and the recording material is conveyed to the second image forming portion Pb, and the next transfer is performed. Thereafter, the recording material on which the toner images formed by the third and fourth image forming portions Pc and Pd are transferred by the same method as described above is discharged by the separation charger (separation electrode) 9 and is subjected to electrostatic adsorption force. As a result of this attenuation, the recording material carrier 18 is separated from the recording material carrier 18 and conveyed to a fixing unit (fixing device) 10.
[0159]
The fixing unit 10 includes a fixing roller 71, a pressure roller 72, heat resistant cleaning members 73 and 74 for cleaning the rollers 71 and 72, heaters 75 and 76 for heating the rollers 71 and 72, and a release agent such as dimethyl silicone. An oil application roller 77 for applying oil to the fixing roller 71, an oil reservoir 78 for supplying the oil, and a thermistor 79 for fixing temperature control are included.
[0160]
After the transfer, the toner remaining on the photosensitive drums la, lb, lc, and ld is removed by the photosensitive member cleaning units 5a, 5b, 5c, and 5d, and is prepared for the subsequent latent image formation. Further, the toner and the like remaining on the image support 8 are removed by the belt static eliminator 12 and the electrostatic adsorption force is removed, and then removed by the cleaning device 62 having a nonwoven fabric in this example. As the cleaning device 62, a rotating fur brush, a blade, or a device using these in combination is also used.
[0161]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[0162]
Example 1
<< Preparation of Latex 1 >>
A solution prepared by dissolving 7.08 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) in ion-exchanged water (2760 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. Add. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, 72.0 g of Exemplified Compound 19) was added to a monomer composed of 115.1 g of styrene, 42.0 g of n-butyl acrylate, and 10.9 g of methacrylic acid, and heated to 80 ° C. and dissolved to prepare a monomer solution. Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Subsequently, a solution in which 0.84 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and the mixture was heated and stirred at 80 ° C. for 3 hours to prepare latex particles. Subsequently, a solution obtained by further dissolving 7.73 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water was added, and after 15 minutes, 383.6 g of styrene, 140.0 g of n-butyl acrylate, 36. A mixed solution of 4 g and 14.0 g of n-octyl-3-mercaptopropionic acid ester was dropped over 120 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain latex particles.
[0163]
This latex particle is designated as Latex 1.
<< Manufacture of colored particles >>
(Manufacture of colored particles 1Bk)
Sodium n-dodecyl sulfate = 9.2 g is dissolved in 160 ml of ion-exchanged water with stirring. Under stirring, 20 g of Legal 330R (carbon black manufactured by Cabot Corporation) was gradually added, and then dispersed using CLEARMIX. As a result of measuring the particle diameter of the dispersion using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd., the weight average diameter was 112 nm. This dispersion is referred to as “colorant dispersion 1”.
[0164]
1250 g of the above-mentioned “Latex 1”, 2000 ml of ion-exchanged water, and “Colorant dispersion 1” are placed in a 5-liter four-necked flask equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting to 30 ° C., a 5 mol / liter aqueous sodium hydroxide solution was added to this solution to adjust the pH to 10.0. Subsequently, an aqueous solution in which 52.6 g of magnesium chloride hexahydrate was dissolved in 72 ml of ion-exchanged water was added at 30 ° C. for 5 minutes with stirring. Thereafter, after standing for 2 minutes, temperature increase is started, and the temperature is raised to 90 ° C. in 5 minutes (temperature increase rate = 12 ° C./min). In that state, the particle size was measured with a Coulter Counter TAII, and when the volume average particle size reached 4.3 μm, an aqueous solution in which 115 g of sodium chloride was dissolved in 700 ml of ion-exchanged water was added to stop the particle growth and continue. Then, the mixture is heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 8 hours to cause salting out / fusion. Then, it cooled to 30 degreeC on the conditions of 6 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced colored particles were filtered / washed under the following conditions, and then dried with hot air at 40 ° C. to obtain colored particles. This is referred to as “colored particles 1Bk”.
[0165]
(Production of colored particles 1Y)
In the production of colored particles 1Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Yellow 185 was used. This is designated as “colored particles 1Y”.
[0166]
(Production of colored particles 1M)
In the production of colored particles 1Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Red 122 was used. This is designated as “colored particles 1M”.
[0167]
(Production of colored particles 1C)
In the production of colored particles 1Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Blue 15: 3 was used. This is designated as “colored particles 1C”.
[0168]
(Production of colored particles 2Bk, 3Bk, 4Bk and 5Bk)
In the production of colored particles 1Bk, colored particles 2Bk to 5Bk were produced in the same manner except that the production conditions described in Table 1 were changed.
[0169]
(Manufacture of colored particles 6Bk-8Bk)
In the production of the colored particles 1Bk, the production conditions described in Table 1 were set, and when the volume average particle diameter reached 3.8 μm, the particle growth was stopped to produce colored particles 6Bk to 8Bk, respectively. .
[0170]
(Production of colored particles 9Bk to 11Bk)
In the production of the colored particles 1Bk, the production conditions shown in Table 1 were set, and when the volume average particle size became 5.5 μm, the particle growth was stopped to produce colored particles 9Bk to 11Bk, respectively.
[0171]
(Manufacture of colored particles 12Bk and 13Bk)
In the production of the colored particles 1Bk, colored particles 12Bk and 13Bk were produced in the same manner except that the particle growth was stopped when the volume average particle diameters became 1.5 μm and 9.3 μm, respectively.
[0172]
(Manufacture of colored particles 14Bk and 15Bk)
In the production of the colored particles 1Bk, colored particles 14Bk and 15Bk were produced in the same manner except that the particle growth was stopped when the volume average particle diameters reached 5.8 μm and 5.4 μm, respectively.
[0173]
(Production of colored particles 4Y)
Instead of carbon black in the production of colored particles 4Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Yellow 185 was used. This is referred to as “colored particles 4Y”.
[0174]
(Production of colored particles 4M)
Instead of carbon black in the production of colored particles 4Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Red 122 was used. This is designated as “colored particles 4M”.
[0175]
(Production of colored particles 4C)
Instead of carbon black in the production of colored particles 4Bk, C.I. I. Colored particles were obtained in the same manner except that CI Pigment Blue 15: 3 was used. This is designated as “colored particles 4C”.
[0176]
The production conditions of the colored particles are shown in Table 1, and the physical properties of the obtained colored particles are shown in Table 2.
[0177]
[Table 1]

[0178]
[Table 2]

[0179]
(Manufacture of toner particles)
The obtained colored particles 1Bk to 15Bk and the colored particles 1Y, 1M, 1C, 4Y, 4M, and 4C are each 1% by weight of hydrophobic silica (number average primary particle size = 12 nm, hydrophobicity = 68) and hydrophobic. Titanium oxide (number average primary particle size = 20 nm, hydrophobicity = 63) was added and mixed by a Henschel mixer to obtain toners 1Bk to 15Bk, toners 1Y to 1C, and toners 4Y to 4C.
[0180]
The physical properties such as the shape and particle size of the toner were the same as the physical property data of the colored particles shown in Table 2.
[0181]
(Manufacture of developer)
Each of the toner particles is mixed with a silicone carrier-coated ferrite carrier having a volume average particle diameter of 60 μm to produce developers 1Bk to 15Bk, toners 1Y to 1C, and toners 4Y to 4C having a toner concentration of 6%. did.
[0182]
<< Example of photoconductor production >>
(Manufacture of photoconductor A)
A coating solution in which 1.5 parts by mass of a polyamide resin (Amilan CM-8000: manufactured by Toray Industries, Inc.) is dissolved in a mixed solvent of 90 parts by volume of methanol and 10 parts by volume of butanol is dip-coated on an aluminum drum having a diameter of 60 mm. An intermediate layer having a thickness of 0.23 μm was formed. Next, 0.8 parts by mass of polyvinyl butyral (ESREC BL-S: manufactured by Sekisui Chemical Co., Ltd.) is dissolved in 100 parts by mass of methyl isopropyl ketone, and 2 parts by mass of titanyl phthalocyanine is mixed and dispersed in the resulting solution. The coating solution was dip-coated on the intermediate layer to form a charge generation layer having a thickness of 0.2 μm after drying. Subsequently, a coating solution obtained by dissolving BPZ (viscosity average molecular weight = 30,000) 20 parts by mass, 15 parts by mass of a charge transport material (T-9) and 100 parts by volume of 1,2-dichloroethane as a polycarbonate is used as the charge generation layer. A first charge transport layer (CTL) having an average film thickness of 4 μm after dip coating was formed.
[0183]
(Manufacture of photoconductors B to E)
In the production of the photoconductor A, photoconductors B to E were produced in the same manner except that the average film thickness after drying of the charge transport layer was changed as shown in Table 3.
[0184]
The average film thickness of each charge transport layer of the obtained photoreceptors A to E and the difference between the maximum film thickness and the minimum film thickness are shown.
[0185]
[Table 3]

[0186]
Next, using the photoreceptors A to E and the developer, an image was formed using a Konica Satios 7040 (digital copying machine), and the obtained images were comparatively evaluated.
[0187]
《Image quality evaluation》
A sheet having a continuous weight of 55 kg was used as a recording material to be used, and an image was formed in the vertical direction. As the image forming conditions, the character “dust” was developed with Mincho / 9.6 points in a high temperature and high humidity environment (32 ° C., 85% RH). The obtained character image of “dust” was copied over 10 generations, and the number of generations that can be read was determined based on the average value of visual determination by 10 members as to whether or not the characters could be read.
[0188]
In the present invention, a high-quality image is a case where it can be sufficiently read as characters even after copying for at least nine generations.
[0189]
《Cleanability evaluation》
Further, 100 half-tones (pixel rate = 30%) are printed continuously in a low-temperature and low-humidity environment (10 ° C., 10% RH). Evaluation was performed. The cleaning method employed blade cleaning.
[0190]
Y: No problem
Δ: Minor cleaning failure occurred
×: Cleaning failure occurred
The results obtained are shown in Table 4.
[0191]
[Table 4]

[0192]
From Table 4, it is clear that the sample of the present invention has higher image quality and better cleaning properties than the comparative sample.
[0193]
Example 2
<Evaluation of color difference>
Evaluation was carried out using a color copying machine having an intermediate transfer member using the developer group and the photosensitive member. A Y / M / C / Bk developer is placed around the multi-layer photoconductor, and each color is developed on the photoconductor and then transferred onto the intermediate transfer member to form a full-color image on the intermediate transfer member. After that, a structure having an intermediate transfer body to be transferred to paper as an image forming support was used. Note that a blade cleaning method was adopted for cleaning the photoreceptor. As the fixing method, a pressure contact type heat fixing device was used.
[0194]
Evaluation was made by printing 1000 sheets of a document with a full color pixel ratio of 25% in a high-temperature and high-humidity environment of 30 ° C./80% RH, and the difference in chroma between the first and 1000th images was evaluated by color difference. The color difference was evaluated by the following method.
[0195]
That is, the color of the solid image portion of the secondary color (red, blue, green) in each image is measured by “Macbeth Color-Eye 7000”, and the color difference is calculated using the CMC (2: 1) color difference formula. The rank was visually evaluated as described.
[0196]
5 or less: Color change is not detected
More than 5 and less than 8: There is a slight change in color to the extent that the color of the skin and food is uncomfortable
More than 8 and less than 9: Color change is clearly detected from red, green and blue
If the color difference obtained by the CMC (2: 1) color difference formula is 5 or less, the color change of the formed image is acceptable.
[0197]
The results obtained are shown in Table 5.
[0198]
[Table 5]

[0199]
From Table 5, it is clear that the samples of the present invention have very little color difference.
[0200]
【The invention's effect】
According to the present invention, it is possible to provide an image forming method that has high image quality, exhibits good cleaning properties, and has little color difference between the initial image of development and the image after running.
[Brief description of the drawings]
FIGS. 1 (1) to (6) are schematic cross-sectional views each showing one embodiment of a photoreceptor used in the present invention.
FIG. 2 is a schematic cross-sectional view of a developing unit used in the image forming method of the present invention.
FIG. 3 is a schematic diagram showing an embodiment of a toner recycling apparatus used in the present invention.
FIG. 4 is a schematic sectional view showing an example of a color electrophotographic image forming apparatus used in the present invention.
[Explanation of symbols]
1 Conductive support
2 Middle layer
3 Charge transport layer (CTL)
4 Charge generation layer (CGL)
5 Protective layer
6 Photosensitive layer
11 Electrophotographic photosensitive drum (photosensitive member)
12 Rubber roller
13 Steel elastic blade
14 Sponge roller
15 Stirring blade
16 Non-magnetic one-component toner
17 Toner tank
21 Developer
22 Developer transport sleeve
23 Developer conveying screw
25 Cleaner part
26 Leaning member (elastic blade)
27 Recycled toner recovery screw
28 Recycled toner transport screw
1a, 1b, 1c, 1d Electrostatic latent image carrier (electrophotographic photosensitive drum, photosensitive drum)
2a, 2b, 2c, 2d drum charger
3a, 3b, 3c, 3d Developer
4a, 4b, 4c, 4d Transfer charger
41a, 41b, 41c, 41d Transfer pressing member
5a, 5b, 5c, 5d Photoconductor cleaning unit
10 Fixing part (fixing device)
16a Tip edge
17a Laser beam exposure apparatus
21a, 21b, 21c, 21d Static elimination exposure lamp
22a, 22b, 22c, 22d Potential sensor
Pa, Pb, Pc, Pd Image forming unit
71, 72 Heating roller
73, 74 Heat-resistant cleaning member
75, 76 heater
77 Oil application roller
78 Oil sump
79 Thermistor

Claims (1)

A latent image formed on an electrostatic latent image carrier having a charge generation layer and a charge transport layer on a conductive support is developed with a developer containing a toner for developing an electrostatic image, and visualized. In an image forming method having a step of transferring to an image support,
At least one of the toners has a 50% volume particle size (Dv50) of 2 μm to 8 μm, and a ratio (Dv50 / Dp50) of the 50% volume particle size (Dv50) and 50% number particle size (Dp50) of the toner. 1.0 to 1.15, a cumulative 75% volume particle size (Dv75) from the larger volume particle size of the toner, and a cumulative 75% number particle size (Dv75) of the toner from the larger one. Dp75 ratio) (Dv75 / Dp75) is 1.0~1.20, 0.7 × (Dp50) following toner number in the whole toner is 10% by number or less, the average film of the charge transport layer thickness 5μm~15μm der is, and the toner, image forming method, wherein a resin particles obtained by polymerizing a polymerizable monomer which is manufactured through a step of salting out / fusing .

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