JP2004037740A - Electrophotographic photoreceptor, process cartridge, and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which effectively suppresses a sensitivity decrease and a residual potential increase caused by providing a protective layer to electrophotographic photoreceptor, has a surface property having excellent durability to wear and scratch, maintains high image quality, and ensures high quality image free from image flow and toner filming caused by developer sticking to a surface, and to provide a process cartridge and an electrophotographic apparatus. <P>SOLUTION: In the electrophotographic photoreceptor having, on a conductive support, at least a photoreceptive layer and the protective layer, the conductive support has a diameter that is less than 30 mm, the protective layer contains at least a curable resin and a charge transport material, and the molecular weight of the charge transport material is 250 to 800. <P>COPYRIGHT: (C)2004,JPO

Description

【００３３】
式中、Ｒ_１は炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示し、Ｒ_２は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいフェニル基を示す。Ａｒ_１及びＡｒ_２は置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を示す。Ａｒ_３は置換基を有してもよいアリーレン基又は２価の置換基を有してもよい複素環基を示す。ｍ及びｎはそれぞれ０又は１である。ただし、ｎ＝０の時、ｍ＝０である。α及びβはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示す。
【００３４】
【化２】

【００３５】
式中、Ｒ_３は炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示す。Ａｒ_４及びＡｒ_５は置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を示す。γ及びδはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示す。なお、γ及びδは置換基を介して共同で環をなしてもよい。ｐは０又は１である。
【００３６】
【化３】

【００３７】
式中、Ｒ_４及びＲ_５はそれぞれ炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示す。Ａｒ_６は置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を示す。ε、ζ、η及びθはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基、置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示す。なお、εとζ及びηとθは置換基を介して共同で環をなしてもよい。ｑ及びｒはそれぞれ０又は１である。
【００３８】
上記式（１）〜（３）における置換基等の構造について以下に詳しく説明する。
【００３９】
式中、Ｒ_１及びＲ_３〜Ｒ_５はそれぞれ炭素数１〜８の枝分かれしてもよい、メチレン基、エチレン基、プロピレン基及びブチレン基等の２価の炭化水素基を示す。Ｒ_２は水素原子、置換基を有してもよいメチル基、エチル基、プロピル基及びブチル基等のアルキル基、置換基を有してもよいベンジル基、フェネチル基及びナフチルメチル基等のアラルキル基、又はフェニル基を示す。
【００４０】
式中、α、β、γ、δ、ε、ζ、η及びθが示すベンゼン環が有してもよい置換基としては、フッ素、塩素、臭素及びヨウ素等のハロゲン原子、置換基を有してもよいメチル基、エチル基、プロピル基及びブチル基等のアルキル基、置換基を有してもよいメトキシ基、エトキシ基、プロポキシ基及びブトキシ基等のアルコキシ基、置換基を有してもよいフェニル基、ナフチル基、アンスリル基及びピレニル基等のアリール基、又は置換基を有してもよいピリジル基、チエニル基、フリル基及びキノリル基等の複素環基を示す。また、γとδ、εとζ、及びηとθは共同でそれぞれが結合している置換基等を介して、フルオレン骨格やジヒドロフェナントレン骨格等の環状構造を形成してもよい。
【００４１】
式中、Ａｒ_１、Ａｒ_２、Ａｒ_４、Ａｒ_５及びＡｒ_６は置換基を有してもよいメチル基、エチル基、プロピル基及びブチル基等のアルキル基、置換基を有してもよいベンジル基、フェネチル基及びナフチルメチル基等のアラルキル基、置換基を有してもよいフェニル基、ナフチル基、アンスリル基及びピレニル基等のアリール基、又は置換基を有してもよいピリジル基、チエニル基、フリル基及びキノリル基等の複素環基を示す。Ａｒ_３は置換基を有してもよいフェニレン基、ナフチレン基、アンスリレン基及びピレニレン基等のアリーレン基、ピリジレン基、又はチエニレン基等の２価の複素環基を示す。
【００４２】
式（１）〜（３）において有してもよい置換基としては、メチル基、エチル基、プロピル基及びブチル基等のアルキル基、ベンジル基、フェネチル基及びナフチルメチル基等のアラルキル基、フェニル基、ナフチル基、アンスリル基、ピレニル基、フルオレニル基、カルバゾリル基、ジベンゾフリル基及びジベンゾチオフェニル基等の芳香環基、メトキシ基、エトキシ基及びプロポキシ基等のアルコキシ基、フェノキシ基及びナフトキシ基等のアリールオキシ基、フッ素、塩素、臭素及びヨウ素等のハロゲン原子、ニトロ基及びシアノ基等が挙げられる。
【００４３】
本発明に用いられるヒドロキシアルキル基及びヒドロキシアルコキシ基より選ばれる置換基を少なくとも一つ有する該電荷輸送材料は、下記式（４）〜（６）のいずれかで示される化合物であることが好ましく、これらの少なくとも１種を含有する保護層を有する電子写真感光体より構成されることが好ましい。
【００４４】
【化４】

【００４５】
式中、Ｒ_６、Ｒ_７及びＲ_８はそれぞれ炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示し、ι、κ及びλはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示し、ａ、ｂ及びｄは０又は１であり、ｓ及びｔは０又は１である。
【００４６】
【化５】

【００４７】
式中、Ｒ_９、Ｒ_１０及びＲ_１１はそれぞれ炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示し、μ及びνはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示し、ｅ、ｆ及びｇは０又は１である。ｕ、ｗ及びｖは０又は１であり、総てが同時に０になることはない。Ｚ_１及びＺ_２はそれぞれハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を示し、共同で環をなしてもよい。
【００４８】
【化６】

【００４９】
式中、Ｒ_１２、Ｒ_１３、Ｒ_１４及びＲ_１５はそれぞれ炭素数１〜８の枝分かれしてもよい２価の炭化水素基を示し、ξ、π、ρ及びσはそれぞれ置換基としてハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を一つ以上有してもよいベンゼン環を示し、ｈ、ｉ、ｊ及びｋは０又は１であり、ｘ、ｙ及びｚは０又は１である。Ｚ_３及びＺ_４はそれぞれハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアルコキシ基、置換基を有してもよいアリール基又は置換基を有してもよい複素環基を示し、共同で環をなしてもよい。
【００５０】
上記式（４）〜（６）における置換基等の構造について以下に詳しく説明する。
【００５１】
式中、Ｒ_６〜Ｒ_１５はそれぞれ炭素数１〜８の枝分かれしてもよい、メチレン基、エチレン基、プロピレン基及びブチレン等の２価の炭化水素基を示す。
【００５２】
式中、ι、κ、λ、μ、ν、ξ、π、ρ及びσが示すベンゼン環が有してもよい置換基としては、フッ素、塩素、臭素及びヨウ素等のハロゲン原子、置換基を有してもよいメチル基、エチル基、プロピル基及びブチル基等のアルキル基、置換基を有してもよいメトキシ基、エトキシ基、プロポキシ基及びブトキシ基等のアルコキシ基、置換基を有してもよいフェニル基、ナフチル基、アンスリル基及びピレニル基等のアリール基、又は置換基を有してもよいピリジル基、チエニル基、フリル基及びキノリル基等の複素環基を示す。
【００５３】
式中、Ｚ_１〜Ｚ_４はフッ素、塩素、臭素及びヨウ素等のハロゲン原子、置換基を有してもよいメチル基、エチル基、プロピル基及びブチル基等のアルキル基、置換基を有してもよいメトキシ基、エトキシ基、プロポキシ基及びブトキシ基等のアルコキシ基、置換基を有してもよいフェニル基、ナフチル基、アンスリル基及びピレニル基等のアリール基、又は置換基を有してもよいピリジル基、チエニル基、フリル基及びキノリル基等の複素環基を示す。Ｚ_１とＺ_２及びＺ_３とＺ_４は共同でそれぞれが結合しているビフェニル骨格を介して、フルオレン骨格やジヒドロフェナントレン骨格等の環状構造を形成してもよい。
【００５４】
式（４）〜（６）において有してもよい置換基としては、メチル基、エチル基、プロピル基及びブチル基等のアルキル基、ベンジル基、フェネチル基及びナフチルメチル基等のアラルキル基、フェニル基、ナフチル基、アンスリル基、ピレニル基、フルオレニル基、カルバゾリル基、ジベンゾフリル基及びジベンゾチオフェニル基等の芳香環基、メトキシ基、エトキシ基及びプロポキシ基等のアルコキシ基、フェノキシ基及びナフトキシ基等のアリールオキシ基、フッ素、塩素、臭素及びヨウ素等のハロゲン原子、ニトロ基及びシアノ基等が挙げられる。
【００５５】
本発明において用いられる電荷輸送材料は、その相溶性を更に良好にし、高い電荷輸送性を持たせるために、式（１）〜（３）に示されるトリフェニルアミン誘導体であることが好ましく、また、式（４）〜（６）中のＲ_６〜Ｒ_１５で示される２価の炭化水素基は炭素数４以下であることが好ましく、更にはヒドロキシアルキル基及びヒドロキシアルコキシ基の数が２個以上であることが好ましい。その分子量は２５０以上８００以下であることが必須であり、好ましくは３００以上、７００以下であり、より好ましくは３５０以上６５０以下である。
【００５６】
本発明に用いられる電荷輸送材料は、保護層を作製するための塗工液中に均一に溶解又は分散させ、塗布して形成する。電荷輸送材料と熱硬化性樹脂バインダーの混合割合は、質量比で、電荷輸送材料／熱硬化性樹脂バインダー＝０．１／１０〜２０／１０が好ましく、より好ましくは０．５／１０〜１０／１０である。熱硬化性樹脂バインダーに対して電荷輸送材料が少な過ぎると残留電位低下の効果が小さくなり、多過ぎると保護層の強度を弱める可能性がある。
【００５７】
以下に、本発明で用いられるフェノール基を少なくとも一つ有する電荷輸送材料の具体例を示す。ただし、本発明の電荷輸送材料はこれらに限定されるものではない。
【００５８】
【化７】

【００５９】
【化８】

【００６０】
【化９】

【００６１】
【化１０】

【００６２】
【化１１】

【００６３】
【化１２】

【００６４】
【化１３】

【００６５】
【化１４】

【００６６】
【化１５】

【００６７】
【化１６】

【００６８】
【化１７】

【００６９】
【化１８】

【００７０】
【化１９】

【００７１】
【化２０】

【００７２】
【化２１】

【００７３】
【化２２】

【００７４】
【化２３】

【００７５】
【化２４】

【００７６】
【化２５】

【００７７】
【化２６】

【００７８】
【化２７】

【００７９】
【化２８】

【００８０】
【化２９】

【００８１】
【化３０】

【００８２】
また以下に、本発明で用いられるヒドロキシアルキル基及びヒドロキシアルコキシ基より選ばれる置換基を少なくとも一つ有する電荷輸送材料の具体例を示す。ただし、本発明の電荷輸送材料はこれらに限定されるものではない。
【００８３】
【化３１】

【００８４】
【化３２】

【００８５】
【化３３】

【００８６】
【化３４】

【００８７】
【化３５】

【００８８】
【化３６】

【００８９】
【化３７】

【００９０】
【化３８】

【００９１】
【化３９】

【００９２】
【化４０】

【００９３】
【化４１】

【００９４】
【化４２】

【００９５】
【化４３】

【００９６】
【化４４】

【００９７】
【化４５】

【００９８】
【化４６】

【００９９】
【化４７】

【０１００】
【化４８】

【０１０１】
【化４９】

【０１０２】
【化５０】

【０１０３】
【化５１】

【０１０４】
【化５２】

【０１０５】
【化５３】

【０１０６】
【化５４】

【０１０７】
保護層は、無機微粒子、有機微粒子のいずれか一方、あるいは両方を含有することができ、微粒子としては、保護層の抵抗調整機能を有する導電性の粒子が好ましく、また保護層の耐摩耗性から潤滑性の粒子が好ましい。
【０１０８】
本発明において、保護層の体積抵抗率を調整する補助的な役割を担うものとして、導電性粒子を用いてもよい。その例としては、金属、金属酸化物及びカーボンブラック等が挙げられる。金属としては、アルミニウム、亜鉛、銅、クロム、ニッケル、銀及びステンレス等、又はこれらの金属をプラスチックの粒子の表面に蒸着したもの等が挙げられる。金属酸化物としては、酸化亜鉛、酸化チタン、酸化スズ、酸化アンチモン、酸化インジウム、酸化ビスマス、酸化アルミナ、スズをドープした酸化インジウム、アンチモンやタンタルをドープした酸化スズ及びアンチモンをドープした酸化ジルコニウム等が挙げられる。これらは単独で用いることも、２種以上を組み合わせて用いることもできる。２種以上を組み合わせて用いる場合は、単に混合しても、固溶体や融着の形にしてもよい。
【０１０９】
本発明においては、上述した導電性粒子の中でも透明性の点で金属酸化物を用いることが好ましい。更に、これら金属酸化物の中でも酸化スズを用いることが特に好ましい。酸化スズは、分散性や液安定性を改良する目的で後述の表面処理されていてもよく、抵抗制御性を良くする目的でアンチモンやタンタルをドープされていてもよい。
【０１１０】
上記の金属や金属酸化物の一部は、保護層に含むことにより、保護層の削れ量低減の効果も同時に示すものがある。
【０１１１】
本発明において用いられる保護層は、本質的に抵抗体として電荷の移動をさせるものではなく、保護層中に含有させた電荷輸送材料により電荷を移動させて、保護層を施した電子写真感光体の感度を維持し、残留電位を低下させるものである。従って、抵抗体としての体積抵抗率は低く設定する必要はなく、その体積抵抗率として、１×１０^１２Ω・ｃｍ以上にすることにより、形成された静電潜像の流れ等を高い次元で抑制することができる。
【０１１２】
本発明における導電性微粒子は、保護層の体積抵抗率を調整する補助的な役割を担うものであり、必要なければ必ずしも用いなくてよい。
【０１１３】
膜強度的には、導電性粒子の量が増えれば増えるほど弱くなるため、導電性粒子の量は、保護層の体積抵抗及び残留電位が許容できる範囲において、少なくする方が好ましい。
【０１１４】
本発明においては、保護層の潤滑性を向上させるためにフッ素原子含有樹脂粒子を含んでもよい。その例としては、四フッ化エチレン、三フッ化塩化エチレン樹脂、六フッ化エチレンプロピレン樹脂、フッ化ビニル樹脂、フッ化ビニリデン樹脂、二フッ化二塩化エチレン樹脂及びこれらの共重合体の中から１種あるいは２種以上を適宜選択するのが好ましいが、特に、四フッ化エチレン樹脂及びフッ化ビニリデン樹脂が好ましい。樹脂粒子の分子量分布や粒径は適宜選択することができ、特に制限されるものではない。
【０１１５】
本発明に用いられる導電性又は潤滑性を有する微粒子の平均粒径は０．００５〜３μｍが好ましい。また、保護層の透明性、膜厚、硬化性等の点から０．３μｍ以下が好ましく、特には０．１μｍ以下が好ましい。
【０１１６】
このフッ素原子含有樹脂粒子を導電性粒子と共に樹脂溶液中で相互の粒子を凝集させないように、フッ素原子含有化合物を導電性粒子の分散時に添加したり、また、導電性粒子の表面をフッ素原子含有化合物で表面処理するとよい。フッ素原子含有化合物を添加又は導電性粒子に表面処理を行うことにより、フッ素原子含有化合物のない場合に比べて、樹脂溶液中での導電性粒子とフッ素原子含有樹脂粒子の分散性及び分散安定性が格段に向上した。また、フッ素原子含有化合物を添加し導電性粒子を分散した液、又は表面処理を施した導電性粒子を分散した液に、フッ素原子含有樹脂粒子を分散することによって分散粒子の二次粒子の形成もなく、経時的にも非常に安定した分散性の良好な塗工液が得られる。
【０１１７】
本発明におけるフッ素原子含有化合物としては、含フッ素シランカップリング剤、フッ素変性シリコーンオイル及びフッ素系界面活性剤等が挙げられる。以下に、好ましい化合物例を表１〜表３に挙げるが、本発明はこれらの化合物に限定されるものではない。
【０１１８】
【表１】

【０１１９】
【表２】

【０１２０】
【表３】

【０１２１】
導電性粒子の表面処理方法としては、導電性粒子と表面処理剤とを適当な溶剤中で混合、分散し、表面処理剤を導電性粒子表面に付着させる。分散の方法としては、ボールミルやサンドミル等の通常の分散手段を用いることができる。次に、この分散溶液から溶剤を除去し、導電性粒子表面に固着させればよい。また、必要に応じて、この後更に熱処理を行ってもよい。また、処理液中には反応促進のための触媒を添加することもできる。更に、必要に応じて表面処理後の導電性粒子に更に粉砕処理を施すことができる。
【０１２２】
導電性粒子に対するフッ素原子含有化合物の割合は、粒子の粒径、形状及び表面積等に影響を受けるが、表面処理済みの導電性粒子全質量に対し、１〜６５質量％が好ましく、より好ましくは１〜５０質量％である。
【０１２３】
更に、本発明においては、より環境安定性のある保護層とするために、下記式（７）で示されるシロキサン化合物を導電性粒子分散時に添加したり、又は、下記式（７）で示されるシロキサン化合物で表面処理を施した導電性粒子を混合することにより、更に環境安定性により優れた保護層を得ることができる。
【０１２４】
【化５５】

【０１２５】
式中、Ａは水素原子又はメチル基であり、かつ、Ａの全部における水素原子の割合は０．１〜５０％の範囲、ｎは０以上の整数である。
【０１２６】
このシロキサン化合物を添加後分散した塗工液、又は、これを表面処理した導電性金属酸化物微粒子を溶剤に溶かした結着樹脂中に分散することによって、分散粒子の二次粒子の形成もなく、経時的にも安定した分散性の良好な塗工液が得られ、更にこの塗工液より形成した保護層は透明性が高く、耐環境性に特に優れた膜が得られる。
【０１２７】
式（７）で示されるシロキサン化合物の分子量は特に制限されるものではないが、表面処理をする場合は、その容易さからは粘度が高過ぎない方がよく、重量平均分子量で数百〜数万程度が適当である。
【０１２８】
表面処理の方法としては、湿式と乾式の二通りがある。湿式では導電性金属酸化物粒子を式（７）で示されるシロキサン化合物とを溶剤中で分散し、該シロキサン化合物を微粒子表面に付着させる。分散の手段としては、ボールミルやサンドミル等の一般の分散手段を使用することができる。次に、この分散溶液を導電性金属酸化物微粒子表面に固着させる。
【０１２９】
この熱処理においては、シロキサン中のＳｉ−Ｈ結合が熱処理過程において空気中の酸素によって水素原子の酸化が起こり、新たなシロキサン結合ができる。その結果、シロキサンが三次元構造にまで発達し、導電性金属酸化物微粒子表面がこの網状構造で包まれる。このように表面処理は、該シロキサン化合物を導電性金属酸化物微粒子表面に固着させることによって完了するが、必要に応じて処理後の微粒子に粉砕処理を施してもよい。乾式処理においては、溶剤を用いずに該シロキサン化合物と導電性金属酸化物微粒子とを混合し混練を行うことによってシロキサン化合物を微粒子表面に付着させる。その後は、湿式処理と同様に熱処理や粉砕処理を施して表面処理を完了する。
【０１３０】
保護層の塗工液を分散する溶剤としては、熱硬化性樹脂を良く溶解し、電荷輸送材料も良く溶解し、導電性微粒子を用いる場合はその分散性が良好で、更にフッ素原子含有化合物、フッ素原子含有樹脂粒子、シロキサン化合物を用いる場合は相溶性や処理性が良好で、更に、保護層の塗工液と接触する電荷輸送層に悪影響を与えない溶剤が好ましい。
【０１３１】
従って、溶剤としては、メタノール、エタノール及び２−プロパノール等のアルコール類、アセトン及びメチルエチルケトン等のケトン類、酢酸メチル及び酢酸エチル等のエステル類、テトラヒドロフラン及びジオキサン等のエーテル類、トルエン、キシレン等の芳香族炭化水素類、クロロベンゼン、ジクロロメタン等のハロゲン系炭化水素類等が使用可能であり、更にこれらを混合して用いてもよい。これらの中でも、熱硬化性樹脂の形態に最も好適な溶剤は、メタノール、エタノール及び２−プロパノール等のアルコール類である。
【０１３２】
本発明の保護層の塗布方法としては、浸漬コーティング法、スプレーコーティング法、スピンナーコーティング法、ローラーコーティング法、マイヤーバーコーティング法及びブレードコーティング法等の一般的な塗工方法を用いることができる。
【０１３３】
本発明の保護層の膜厚は、薄過ぎると電子写真感光体の耐久性を損ない、厚過ぎると保護層を設けたことによる残留電位が上昇するため、適度な厚さにする必要がある。具体的には０．１μｍ〜１０μｍの範囲が好ましく、より好ましくは０．５μｍ〜７μｍの範囲である。
【０１３４】
本発明においては、前記保護層中に、帯電時に発生するオゾンやＮＯｘ等の活性物質の付着による表面層の劣化等を防止する目的で、酸化防止剤の添加材を加えてもよい。
【０１３５】
次に、感光層について以下に説明する。
【０１３６】
本発明の電子写真感光体は、主に積層構造を有することが好ましい。図１（ａ）の電子写真感光体は、導電性支持体４の上に電荷発生層３、電荷輸送層２が順に設けており、更に最表面に保護層１を設けている。また、図１（ｂ）及び（ｃ）の様に導電性支持体と電荷発生層の間に、結着層５、更には干渉縞防止等を目的とする下引き層６を設けてもよい。
【０１３７】
導電性支持体４としては、支持体自身が導電性を持つもの、例えばアルミニウム、アルミニウム合金及びステンレス等の金属を用いることができ、その他にアルミニウム、アルミニウム合金又は酸化インジウム−酸化スズ合金等を真空蒸着によって被膜形成された層を有する前記導電性支持体やプラスチック、導電性微粒子（例えば、カーボンブラック、酸化スズ、酸化チタン及び銀粒子等）を適当なバインダーと共にプラスチックや紙に含浸した支持体、導電性バインダーを有するプラスチック等を用いることができる。但し、本発明においては、直径がφ３０ｍｍ未満である。
【０１３８】
また、導電性支持体と感光層の間には、バリアー機能と接着機能を持つ結着層（接着層）を設けることができる。結着層は、感光層の接着性改良、塗工性改良、支持体の保護、支持体の欠陥の被覆、支持体からの電荷注入性改良、感光層の電気的破壊に対する保護等のために形成される。結着層はカゼイン、ポリビニルアルコール、エチルセルロース、エチレン−アクリル酸コポリマー、ポリアミド、変性ポリアミド、ポリウレタン、ゼラチン又は酸化アルミニウム等によって形成できる。結着層の膜厚は、５μｍ以下が好ましく、より好ましくは０．１〜３μｍである。
【０１３９】
本発明に用いられる電荷発生材料としては、（１）モノアゾ、ジスアゾ及びトリスアゾ等のアゾ系顔料、（２）金属フタロシアニン及び非金属フタロシアニン等のフタロシアニン系顔料、（３）インジゴ及びチオインジゴ等のインジゴ系顔料、（４）ペリレン酸無水物及びペリレン酸イミド等のペリレン系顔料、（５）アンスラキノン及びピレンキノン等の多環キノン系顔料、（６）スクワリリウム色素、（７）ピリリウム塩及びチアピリリウム塩類、（８）トリフェニルメタン系色素、（９）セレン、セレン−テルル及びアモルファスシリコン等の無機物質、（１０）キナクリドン顔料、（１１）アズレニウム塩顔料、（１２）シアニン染料、（１３）キサンテン色素、（１４）キノンイミン色素、（１５）スチリル色素、（１６）硫化カドミウム及び（１７）酸化亜鉛等が挙げられる。
【０１４０】
電荷発生層に用いる結着樹脂としては、例えば、ポリカーボネート樹脂、ポリエステル樹脂、ポリアリレート樹脂、ブチラール樹脂、ポリスチレン樹脂、ポリビニルアセタール樹脂、ジアリルフタレート樹脂、アクリル樹脂、メタクリル樹脂、酢酸ビニル樹脂、フェノール樹脂、シリコーン樹脂、ポリスルホン樹脂、スチレン−ブタジエン共重合体樹脂、アルキッド樹脂、エポキシ樹脂、尿素樹脂及び塩過ビニル−酢酸ビニル共重合体樹脂等が挙げられるが、これらに限定されるものではない。これらは単独、混合あるいは共重合体ポリマーとして１種又は２種以上用いることができる。
【０１４１】
電荷発生層用塗工液に用いる溶剤は、使用する樹脂や電荷発生材料の溶解性や分散安定性から選択されるが、有機溶剤としてはアルコール類、スルホキシド類、ケトン類、エーテル類、エステル類、脂肪族ハロゲン化炭化水素類又は芳香族化合物等を用いることができる。
【０１４２】
電荷発生層３は、前記の電荷発生材料を０．３〜４倍量の結着樹脂、及び溶剤と共に、ホモジナイザー、超音波、ボールミル、サンドミル、アトライター、ロールミル等の方法で十分に分散し、塗布、乾燥されて形成される。その厚みは、５μｍ以下、特には０．０１〜１μｍの範囲が好ましい。
【０１４３】
また、電荷発生層には、種々の増感剤、酸化防止剤、紫外線吸収剤、可塑剤及び公知の電荷発生材料を必要に応じて添加することもできる。
【０１４４】
用いられる電荷輸送材料としては、各種トリアリールアミン系化合物、各種ヒドラゾン系化合物、各種スチリル系化合物、各種スチルベン系化合物、各種ピラゾリン系化合物、各種オキサゾール系化合物、各種チアゾール系化合物及び各種トリアリールメタン系化合物等が挙げられる。
【０１４５】
電荷輸送層２を形成するのに用いられる結着樹脂としては、アクリル樹脂、スチレン系樹脂、ポリエステル、ポリカーボネート樹脂、ポリアリレート、ポリサルホン、ポリフェニレンオキシド、エポキシ樹脂、ポリウレタン樹脂、アルキド樹脂及び不飽和樹脂等から選ばれる樹脂が好ましい。特に好ましい樹脂としては、ポリメチルメタクリレート、ポリスチレン、スチレン−アクリロニトリル共重合体、ポリカーボネート樹脂及びジアリルフタレート樹脂が挙げられる。
【０１４６】
電荷輸送層２は一般的には前記の電荷輸送材料と結着樹脂を溶剤に溶解し、塗布して形成する。電荷輸送材料と結着樹脂との混合割合は２：１〜１：２程度である。溶剤としては、アセトン、メチルエチルケトン等のケトン類、酢酸メチル、酢酸エチル等のエステル類、トルエン、キシレン等の芳香族炭化水素類、クロロベンゼン、クロロホルム、四塩化炭素等の塩素系炭化水素類等が用いられる。この溶液を塗布する際には、例えば浸漬コーティング法、スプレーコーティング法、スピンナーコーティング法等のコーティング法を用いることができ、乾燥は１０℃〜２００℃、好ましくは２０℃〜１５０℃の範囲の温度で、５分〜５時間、好ましくは１０分〜２時間の時間で送風乾燥又は静止乾燥下で行うことができる。
【０１４７】
電荷輸送層は、上述の電荷発生層と電気的の接続されており、電界の存在下で電荷発生層から注入された電荷キャリアを受け取ると共に、これ等の電荷キャリアを保護層との界面まで輸送する機能を有している。この電荷輸送層は、電荷キャリアを輸送する限界があるので必要以上に膜厚を厚くすることができないが、５〜４０μｍが好ましく、特には７〜３０μｍの範囲が好ましい。
【０１４８】
更に、電荷輸送層中に酸化防止剤、紫外線吸収剤、可塑剤又は公知の電荷輸送材料を必要に応じて添加することもできる。
【０１４９】
本発明では更に、この電荷輸送層の上に前記保護層を塗布、硬化させて成膜することで完成される。
【０１５０】
図２に本発明の電子写真感光体を有するプロセスカートリッジを備えた電子写真装置の概略構成を示す。
【０１５１】
図２において、１１はドラム状の本発明の電子写真感光体であり、軸１２を中心に矢印方向に所定の周速度で回転駆動される。電子写真感光体１１は、回転過程において、一次帯電手段１３によりその周面に正又は負の所定電位の均一帯電を受け、次いで、スリット露光やレーザービーム走査露光等の露光手段（不図示）から出力される目的の画像情報の時系列電気デジタル画像信号に対応して強度変調された露光光１４を受ける。こうして電子写真感光体１１の周面に対し、目的の画像情報に対応した静電潜像が順次形成されていく。
【０１５２】
形成された静電潜像は、次いで現像手段１５によりトナー現像され、不図示の給紙部から電子写真感光体１１と転写手段１６との間に電子写真感光体１１の回転と同期して取り出されて給送された転写材１７に、電子写真感光体１１の表面に形成担持されているトナー画像が転写手段１６により順次転写されていく。
【０１５３】
トナー画像の転写を受けた転写材１７は、電子写真感光体面から分離されて像定着手段１８へ導入されて像定着を受けることにより画像形成物（プリント、コピー）として装置外へプリントアウトされる。
【０１５４】
像転写後の電子写真感光体１１の表面は、クリーニング手段１９によって転写残りトナーの除去を受けて清浄面化され、更に前露光手段（不図示）からの前露光光２０により除電処理された後、繰り返し画像形成に使用される。なお、一次帯電手段１３が帯電ローラー等を用いた接触帯電手段である場合は、前露光は必ずしも必要ではない。
【０１５５】
本発明においては、上述の電子写真感光体１１、一次帯電手段１３、現像手段１５及びクリーニング手段１９等の構成要素のうち、複数のものを容器に納めてプロセスカートリッジとして一体に結合して構成し、このプロセスカートリッジを複写機やレーザービームプリンター等の電子写真装置本体に対して着脱自在に構成してもよい。例えば、一次帯電手段１３、現像手段１５及びクリーニング手段１９の少なくとも一つを電子写真感光体１１と共に一体に支持してカートリッジ化して、装置本体のレール等の案内手段２２を用いて装置本体に着脱自在なプロセスカートリッジ２１とすることができる。
【０１５６】
また、露光光１４は、電子写真装置が複写機やプリンターである場合には、原稿からの反射光や透過光、あるいは、センサーで原稿を読取り、信号化し、この信号に従って行われるレーザービームの走査、ＬＥＤアレイの駆動又は液晶シャッターアレイの駆動等により照射される光である。
【０１５７】
本発明の電子写真感光体は、電子写真複写機に利用するのみならず、レーザービームプリンター、ＣＲＴプリンター、ＬＥＤプリンター、ＦＡＸ、液晶プリンター及びレーザー製版等の電子写真応用分野にも幅広く適用し得るものである。
【０１５８】
【実施例】
以下に、具体的な実施例を挙げて本発明を更に詳細に説明する。ただし、本発明の実施の形態は、これらに限定されるものではない。なお、実施例中の「部」は「質量部」を意味する。
【０１５９】
（実施例１）
長さ２４６ｍｍ、直径２４ｍｍのアルミニウムシリンダー（ＪＩＳ　Ａ３００３アルミニウム合金）を支持体として、この上にポリアミド樹脂（商品名：アミランＣＭ８０００、東レ製）の５質量％メタノール溶液を浸漬法で塗布し、膜厚が０．５μｍの下引き層を設けた。
【０１６０】
次に、電荷発生材料として下記式で示されるＣｕＫαの特性Ｘ線回折におけるブラッグ角（２θ±０．２゜）の９．６°及び２７．２゜に強いピークを有する結晶型であるオキシチタニウムフタロシアニン顔料４部、
【０１６１】
【化５６】

ポリビニルブチラール樹脂ＢＸ−１（積水化学（株）製）２部、及び、シクロヘキサノン１１０部を、φ１ｍｍガラスビーズを用いてサンドミルで、４．５時間分散した。その後、酢酸エチル１３０部で希釈し電荷発生層用塗工液とした。上記塗工液を先の下引き層上に浸漬法で塗布し、膜厚が０．１８μｍの電荷発生層を形成した。
【０１６２】
次いで、下記式で示される電荷輸送材料７．５部、
【０１６３】
【化５７】

及びビスフェノールＺ型ポリカーボネート（商品名：Ｚ−２００、三菱ガス化学製）１０部を、モノクロロベンゼン６０部／ジクロロメタン２０部に溶解した。この溶液を、前記電荷発生層上に浸漬塗布し、１１０℃で１時間熱風乾燥し、膜厚が１５μｍの電荷輸送層を形成した。
【０１６４】
次に、保護層として樹脂成分として、レゾール型硬化性フェノール樹脂（商品名：ＰＲ−５３１２３、住友デュレズ（株）製）５４部（不揮発分４５％）、電荷輸送材料としてフェノール基を有する化合物例Ｎｏ．１−１４（分子量５４１．７２）を１５部溶解し、更に、ポリテトラフルオロエチレン微粒子｛平均粒径０．１８μｍ、粒度分布計（製品名：ＣＡＰＡ７００、堀場製作所）にて測定｝１８部を加えて、アセトン３５部で希釈して保護層用塗工液とした。この塗工液を用いて、先の電荷輸送層上に浸漬塗布法により、膜を形成した後、１４５℃で１時間熱風乾燥し、膜厚が２μｍの保護層を形成した。
【０１６５】
（実施例２）
実施例１において、保護層の硬化性樹脂をアクリルポリオール樹脂（商品名：アクリディックＡ−８０１Ｐ、不揮発分５０％、大日本インキ化学工業（製））４５部、及ブロックイソシアネート（商品名：バーノックＤＮ９９５、不揮発分７５％、大日本インキ化学工業（株）製））を７部とした以外は、実施例１と同様にして電子写真感光体を作製した。
【０１６６】
（実施例３）
実施例１において、保護層の硬化性樹脂を下記式で示される熱硬化型のエポキシ樹脂２１部とし、
【０１６７】
【化５８】

更に、硬化触媒として下記式で示される酸無水物４．９部
【０１６８】
【化５９】

を添加した以外は、実施例１と同様にして電子写真感光体を作製した。
【０１６９】
（実施例４）
実施例１において、保護層の電荷輸送材を下記式に示されるヒドラゾン系化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は４９２．７６であった。
【０１７０】
【化６０】

【０１７１】
（実施例５）
実施例１において、保護層の電荷輸送材を下記式に示されるスチリル系化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は５２８．１であった。
【０１７２】
【化６１】

【０１７３】
（実施例６）
実施例１において、保護層の電荷輸送材を下記式に示されるトリアリールアミン化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は４９８．８であった。
【０１７４】
【化６２】

【０１７５】
（実施例７）
実施例１において、保護層の電荷輸送材を化合物例Ｎｏ．４−２３とした以外は、実施例１と同様に電子写真感光体を作製した。この電荷輸送材料の分子量は３６１．４８であった。
【０１７６】
（実施例８）
実施例１と同様に電荷輸送層まで形成した。
【０１７７】
保護層は、アンチモンドープ酸化スズ微粒子１００部を下記式で示されるフッ素原子含有化合物（商品名：ＬＳ−１０９０、信越シリコーン（株）製）７部で表面処理した（処理量７％）、処理済み酸化スズ微粒子３５部と
【０１７８】
【化６３】

エタノール１５０部を、サンドミルにて、６６時間かけて分散を行い、更に、ポリテトラフルオロエチレン微粒子（平均粒径０．１８μｍ）１８部を加えて、更に１２時間サンドミルで分散を行った。
【０１７９】
その後、樹脂成分として、レゾール型硬化性フェノール樹脂（商品名：ＰＲ−５３１２３、住友デュレズ（株）製）５４部（不揮発分４５％）、更に、ヒドロキシアルキル基を有する電荷輸送材料として化合物例Ｎｏ．４−２３を１５部溶解し、エタノール３５部で希釈して保護層用塗工液とした。この塗工液を用いて、先の電荷輸送層上に浸漬塗布法により、膜を形成した後、１４５℃で１時間熱風乾燥し、膜厚が２μｍの保護層を形成した。
【０１８０】
（実施例９）
実施例７において、熱硬化性樹脂を実施例２のウレタン樹脂とした以外は、実施例７と同様にして電子写真感光体を作製した。
【０１８１】
（実施例１０）
実施例７において、熱硬化性樹脂を実施例３と同様のエポキシ樹脂、硬化触媒を添加した以外は、実施例７と同様にして電子写真感光体を作製した。
【０１８２】
（実施例１１）
実施例７において、硬化性樹脂を下記式で示されるアクリル樹脂（ネオペンチルグリコール変性トリメチロールプロパンジアクリレート、商品名：カラヤッドＲ−６０４、日本化薬製）を２０部とし、
【０１８３】
【化６４】

更に、開始剤として下記式で示されるベンゾイン（商品名：ニッソキュアーＭＢ、日本曹達）を４部、
【０１８４】
【化６５】

下記式で示されるベンゾフェノン系エネルギー移動剤（２，２’ジクロロ−４、４’−ジヒドロキシベンゾフェノン）４部
【０１８５】
【化６６】

を加え保護層用塗工液を設けた。次いで、先の電荷輸送層上に浸漬塗布法により、膜を形成した後、高圧水銀灯にて１６０Ｗ／ｃｍ^２の光強度で３２０ｎｍ以下の波長をカットした紫外線を３０秒間照射して光硬化を行ない、その後１００℃で１時間熱風乾燥して保護層を設けた。このとき得られた膜厚は２μｍであった。
【０１８６】
（実施例１２）
実施例７において、硬化性樹脂をトリアルコキシシランとテトラアルコキシシランの加水分解縮合物を主成分とする熱硬化型シリコーン樹脂（商品名：トスガード５１０、東芝シリコーン（株）製）とした。
【０１８７】
（実施例１３）
実施例１において、保護層の電荷輸送材をＮｏ．４−２とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は２８９．１５であった。
【０１８８】
（実施例１４）
実施例１において、保護層の電荷輸送材をＮｏ．２−１とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は３３７．１５であった。
【０１８９】
（実施例１５）
実施例１において、保護層の電荷輸送材をＮｏ．４−７とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は３１９．１６であった。
【０１９０】
（実施例１６）
実施例１において、保護層の電荷輸送材をＮｏ．６−９とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は６６４．３３であった。
【０１９１】
（実施例１７）
実施例１において、保護層の電荷輸送材をＮｏ．６−８とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は７２８．３１であった。
【０１９２】
（実施例１８）
実施例１において、保護層の電荷輸送材をＮｏ．６−２２とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は７６０．４２であった。
【０１９３】
（実施例１９）
実施例１において、保護層の電荷輸送材をＮｏ．２−１９とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は４０５．２１であった。
【０１９４】
（実施例２０）
実施例１において、保護層の電荷輸送材をＮｏ．３−２とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は４４３．１９であった。
【０１９５】
（実施例２１）
実施例１において、保護層の電荷輸送材をＮｏ．５−２２とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は５０１．２２であった。
【０１９６】
（実施例２２）
実施例１において、保護層の電荷輸送材をＮｏ．６−１６とした以外は、実施例１と同様にして電子写真感光体を作製した。電荷輸送材の分子量は６１８．２９であった。
（比較例１）
実施例１において、保護層の電荷輸送材を下記式に示される化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は１９７．２７であった。
【０１９７】
【化６７】

【０１９８】
（比較例２）
実施例１において、保護層の電荷輸送材を下記式に示される化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は８５２．３２であった。
【０１９９】
【化６８】

【０２００】
（比較例３）
実施例１において、保護層の電荷輸送材を下記式に示される化合物とした以外は、実施例１と同様にして電子写真感光体を作製した。この電荷輸送材料の分子量は８７１．４１であった。
【０２０１】
【化６９】

【０２０２】
（比較例４）
実施例１において、保護層に電荷輸送材料を添加しなかった以外は、実施例１と同様にして電子写真感光体を作製した。
【０２０３】
上記のように作製した電子写真感光体を以下のような方法で評価した。電子写真特性の評価は、レーザービームプリンター（商品名：ＬＢＰ−３５０、キヤノン（株）製）に取り付けて行った。電子写真感度として、暗部電位が−７００Ｖになるように帯電設定をし、これに波長７８０ｎｍのレーザー光を照射して−７００Ｖの電位を−２００Ｖまで下げるのに必要な光量を測定し感度とした。更に、２０μＪ／ｃｍ^２の光量を照射した場合の電位を残留電位Ｖｒとして測定した。なお、電位測定は、カートリッジを現像スリーブ位置に表面電位計のプローブが装着できるように改造したものを用いて測定した。また、光量はデジボルに接続したフォトセルをレーザー光が発光している方向に向け電圧を測定した後、換算し光量とした。結果を表４に示す。
【０２０４】
更に、同様のレーザービームプリンターを用いて２５００枚の耐久による削れ量及び画像評価の測定を行った。測定環境は、低温低湿（１０℃／１０％ＲＨ）及び高温高湿（３０℃／８５％ＲＨ）の２環境下で行った。結果を表５に示す。
【０２０５】
耐傷性の評価に関しては以下の方法で行った。電子写真感光体表面にφ０．１ｍｍのダイアモンド針を当接させる。次いで、針に荷重を載せた後、電子写真感光体を５ｍｍ／ｓｅｃの周速で１回転させ、電子写真感光体上に傷を発生させる。荷重を変化させて同様な傷を生じさせ、傷深さを面粗さ計等で測定し、各電子写真感光体の傷に対する優劣を決定する。結果を表６に示す。
【０２０６】
また、過酷保管として、上記のように作成した実施例及び比較例の電子写真感光体をＬＢＰ−３５０のカートリッジに装着し、５０℃／９５％ＲＨの環境下に９０日間放置した後、電子写真感光体の表面及び得られた画像を目視にて観察した。結果を表７に示す。
【０２０７】
【表４】

【０２０８】
【表５】

【０２０９】
【表６】

【０２１０】
【表７】

【０２１１】
【発明の効果】
上述したように、本発明によって、電子写真感光体に保護層を施すことにより問題となる感度低下と残留電位上昇を効率的に抑制することができ、磨耗や傷の発生に対して優れ、また現像剤の表面付着によるトナーフィルミング、画像流れの発生しない高品位の画質を保つことのできる電子写真感光体を提供することが可能となった。更に、該電子写真感光体を有するプロセスカートリッジ及び電子写真装置を提供することが可能となった。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の層構造の例を示す図である。
【図２】本発明の電子写真感光体を有するプロセスカートリッジを備えた電子写真装置の概略構成の例を示す図である。
【符号の説明】
１　保護層
２　電荷輸送層
３　電荷発生層
４　導電性支持体
５　結着層
６　下引き層
１１　電子写真感光体
１２　軸
１３　帯電手段
１４　露光光
１５　現像手段
１６　転写手段
１７　転写材
１８　定着手段
１９　クリーニング手段
２０　前露光光
２１　プロセスカートリッジ
２２　案内手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photoconductor, a process cartridge, and an electrophotographic apparatus, and more particularly, to an electrophotographic photoconductor having a specific surface layer, a process cartridge having the electrophotographic photoconductor, and an electrophotographic apparatus.
[0002]
[Prior art]
In recent years, electrophotographic photoreceptors using organic photoconductive materials have been studied and put to practical use in the market because of their advantages such as high safety, excellent productivity, and low cost.
[0003]
In order to achieve higher speed and higher durability, it is required to improve the mechanical durability of the electrophotographic photosensitive member. For this purpose, studies have been made to provide various protective layers. As the resin used for the protective layer, the curable resin has higher hardness than the thermoplastic resin, and thus has excellent mechanical life and scratch resistance, and is preferable for high durability.
[0004]
When a protective layer is formed solely of a curable resin, it is basically insulative, so that electrophotographic characteristics such as sensitivity deterioration and residual increase become a problem, and the thickness of the protective layer cannot be increased. It cannot be changed. It is conceivable that the protective layer contains a conductive material, or a charge transporting material for the purpose of solving the problem, but in the case of a conductive material, selecting a conductive material and a curable resin in order to maintain environmental stability, It is difficult to optimize the addition amount of the conductive material and adjust the dispersibility and the like.
[0005]
Therefore, it is desirable to add a charge transporting material for the above problem, but there are problems such as solubility in a solvent used for the protective layer, compatibility with the curable resin, and maintenance of charge transporting properties after the protective layer is cured. And optimization was difficult.
[0006]
In addition, although the curable resin has a higher hardness than the thermoplastic resin, it has a tendency to be brittle and easily cracked or damaged by pressure.
[0007]
Further, since the protective layer basically uses a solvent that does not dissolve the photosensitive layer, an interface is formed between the protective layer and the photosensitive layer, adhesion is poor, and the protective layer tends to be easily peeled.
[0008]
Further, in recent years, the diameter of the electroconductive support of the electrophotographic photosensitive member has been reduced due to the miniaturization of the electrophotographic apparatus. is there.
[0009]
Furthermore, when a protective layer is formed of a curable resin alone and mounted on an electrophotographic apparatus and the paper passing is studied, the amount of scraping is small, so that the image flow due to the accumulation of the charged product and the developer of the electrophotographic photosensitive member Toner filming or the like due to surface adhesion may occur. Further, the resin may be deteriorated due to an increase in the residual potential or the atmosphere near the electrophotographic photosensitive member, the sensitivity may be deteriorated, and a fog may be caused on a white background portion on an image.
[0010]
Charging means for charging the electrophotographic photosensitive member, developing means for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner, and cleaning means for collecting the residual toner on the electrophotographic photosensitive member after the transfer step. In recent years, the number of electrophotographic apparatuses using a process cartridge which is integrally supported together with at least one means selected from the group and is detachable from the main body of the electrophotographic apparatus has been increasing. Is in contact with the electrophotographic photoreceptor before the electrophotographic mounting, if any deposits from the charging means, contact pressure, etc., cause cracks on the electrophotographic photoreceptor surface, deposition of the charge transport material, etc. There is.
[0011]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor capable of efficiently suppressing a decrease in sensitivity and a rise in residual potential, which are problems by applying a protective layer to the electrophotographic photoreceptor.
[0012]
Another object of the present invention is to provide an electrophotographic photoreceptor having a surface having excellent durability against abrasion and scratching and capable of maintaining high quality image quality.
[0013]
Another object of the present invention is to provide an electrophotographic photoreceptor capable of maintaining high quality image quality without causing toner filming and image deletion due to the surface adhesion of a developer.
[0014]
Still another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member.
[0015]
[Means for Solving the Problems]
According to the present invention, in an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer on a conductive support, the conductive support has a diameter of less than 30 mm, and the protective layer has at least a curable resin and charge transport. An electrophotographic photoreceptor is provided, which contains a material and has a molecular weight of 250 or more and 800 or less.
[0016]
According to the present invention, a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member are provided.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0018]
Although the molecular weight of the charge transporting material used in the present invention is specified to be 250 or more and 800 or less, if it is less than 250, the hardness which the curable resin can originally have decreases. On the other hand, when the molecular weight exceeds 800, problems such as solubility in a solvent used for the protective layer, compatibility with the curable resin, and possible brittleness of the curable resin occur. The molecular weight of the charge transporting material used in the present invention is more preferably 300 or more and 700 or less, and still more preferably 350 or more and 650 or less.
[0019]
By using a charge transporting material having a defined molecular weight for the protective layer, the detailed reason is unknown, but since the charge transporting material functions as a plasticizer, a conductive support having a small outer diameter is used. Also, good adhesion with the photosensitive layer, peeling, cracking, also without the occurrence of charge transport material precipitation, etc., also improved scratch resistance, further compatibility with the solvent used for the protective layer, The compatibility with the curable resin, the maintenance of the charge transport property after the protective layer is cured, and the like are achieved.
[0020]
In addition, by using a curable resin for the protective layer, the abrasion resistance is excellent, and since a charge transporting material is included, the residual potential is reduced with high sensitivity. Further, the problem of cracks caused by the contact of the charging means is eliminated.
[0021]
Examples of the curable resin used in the protective layer of the present invention include phenol, epoxy, urethane, melamine, xylene, acryl, siloxane, and furan resins. Among these, a resin that hardens without impairing the charge transporting property of the charge transporting material after the formation of the protective layer is preferable. After the protective layer is formed, being cured means that the protective layer hardly dissolves, for example, even when wet with an organic solvent.
[0022]
Of the above resins, epoxy, urethane, acrylic, siloxane and phenol resins are preferred, and thermosetting phenol resins are most suitable for use in the protective layer of the present invention.
[0023]
A thermosetting phenol resin is a resin generally obtained by a reaction between phenols and formaldehyde. There are two types of phenolic resins: resol type obtained by excess formaldehyde with respect to phenol and reaction with an alkali catalyst, and novolak obtained by reacting formaldehyde with excess phenol and acid catalyst. Divided into types.
[0024]
The resol type is also soluble in solvents such as alcohols and ketones, and becomes a cured product by three-dimensionally cross-linking and polymerizing when heated. On the other hand, the novolak type generally does not cure when heated as it is, but produces a cured product by adding a formaldehyde source such as paraformaldehyde or hexamethylenetetramine and heating.
[0025]
Generally, industrially, the resol type is used as a varnish for paints, adhesives, cast products and laminates, and the novolak type is mainly used as a molding material or a binder.
[0026]
The phenolic resin used as the binder resin in the present invention can be used in any of the above resol type and novolak type.However, it can be cured without adding a curing agent, and the resol type can be used because of the operability as a paint. It is preferable to use
[0027]
In the present invention, these phenolic resins can be used alone or as a mixture of two or more, and it is also possible to use a mixture of a resol type and a novolak type. The phenol resin used in the present invention may be any known phenol resin.
[0028]
The protective layer of the present invention is formed by applying a coating solution obtained by dissolving or diluting a thermosetting resin with a solvent or the like on the photosensitive layer, and a polymerization reaction occurs after the coating to form a cured layer. I do. As a form of the polymerization, the polymerization proceeds by an addition and condensation reaction by heat, and after applying a protective layer, the polymerization reaction is caused by heating to form a cured polymer layer.
[0029]
Examples of the charge transport material used in the present invention include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. Can be Among them, it is preferable that the protective layer does not dissolve even after wetting in an organic solvent after the formation of the protective layer. Preferred in the present invention are triarylamine compounds, hydrazone compounds and styryl compounds.
[0030]
Further, the most suitable charge transporting material for the curable resin in the present invention is shown below.
[0031]
The charge transporting material having at least one phenol group used in the present invention is preferably a compound represented by any of the following formulas (1) to (3), and a protective layer containing at least one of these compounds may be used. And an electrophotographic photoreceptor.
[0032]
Embedded image

[0033]
Where R ₁ Represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched; ₂ Represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a phenyl group which may have a substituent. Ar ₁ And Ar ₂ Represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. Ar ₃ Represents an arylene group which may have a substituent or a heterocyclic group which may have a divalent substituent. m and n are each 0 or 1. However, when n = 0, m = 0. α and β each have a halogen atom as a substituent, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent or a substituent. A benzene ring which may have one or more heterocyclic groups.
[0034]
Embedded image

[0035]
Where R ₃ Represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched. Ar ₄ And Ar ₅ Represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. γ and δ each have a halogen atom as a substituent, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent or a substituent. A benzene ring which may have one or more heterocyclic groups. Note that γ and δ may form a ring together through a substituent. p is 0 or 1.
[0036]
Embedded image

[0037]
Where R ₄ And R ₅ Represents a divalent hydrocarbon group which may have 1 to 8 carbon atoms and may be branched. Ar ₆ Represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. ε, ζ, η and θ each represent a halogen atom as a substituent, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, a substituent A benzene ring which may have one or more heterocyclic groups which may have In addition, ε and ζ and η and θ may form a ring together through a substituent. q and r are each 0 or 1.
[0038]
The structures of the substituents and the like in the above formulas (1) to (3) will be described in detail below.
[0039]
Where R ₁ And R ₃ ~ R ₅ Represents a divalent hydrocarbon group having 1 to 8 carbon atoms, which may be branched, such as a methylene group, an ethylene group, a propylene group, and a butylene group. R ₂ Is a hydrogen atom, a methyl group which may have a substituent, an alkyl group such as an ethyl group, a propyl group and a butyl group, a benzyl group which may have a substituent, an aralkyl group such as a phenethyl group and a naphthylmethyl group, Or a phenyl group.
[0040]
In the formula, α, β, γ, δ, ε, ζ, η and θ, the substituent which the benzene ring may have may include a halogen atom such as fluorine, chlorine, bromine and iodine, and a substituent. May have an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an optionally substituted methoxy group, an ethoxy group, an alkoxy group such as a propoxy group and a butoxy group, and may have a substituent. And aryl groups such as phenyl group, naphthyl group, anthryl group and pyrenyl group, and heterocyclic groups such as pyridyl group, thienyl group, furyl group and quinolyl group which may have a substituent. Further, γ and δ, ε and ζ, and η and θ may jointly form a cyclic structure such as a fluorene skeleton or a dihydrophenanthrene skeleton through a substituent or the like bonded to each other.
[0041]
Where Ar ₁ , Ar ₂ , Ar ₄ , Ar ₅ And Ar ₆ Is an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group which may have a substituent, a benzyl group which may have a substituent, an aralkyl group such as a phenethyl group and a naphthylmethyl group, and a substituent. An aryl group such as a phenyl group, a naphthyl group, an anthryl group and a pyrenyl group which may be possessed, or a heterocyclic group such as a pyridyl group, a thienyl group, a furyl group and a quinolyl group which may have a substituent. Ar ₃ Represents an optionally substituted arylene group such as a phenylene group, a naphthylene group, an anthrylene group and a pyrenylene group; a divalent heterocyclic group such as a pyridylene group or a thienylene group.
[0042]
In the formulas (1) to (3), substituents which may be present include alkyl groups such as methyl group, ethyl group, propyl group and butyl group, aralkyl groups such as benzyl group, phenethyl group and naphthylmethyl group, and phenyl. Group, naphthyl group, anthryl group, pyrenyl group, fluorenyl group, carbazolyl group, aromatic ring group such as dibenzofuryl group and dibenzothiophenyl group, alkoxy group such as methoxy group, ethoxy group and propoxy group, phenoxy group and naphthoxy group etc. Aryloxy groups, halogen atoms such as fluorine, chlorine, bromine and iodine, nitro groups and cyano groups.
[0043]
The charge transport material having at least one substituent selected from a hydroxyalkyl group and a hydroxyalkoxy group used in the present invention is preferably a compound represented by any of the following formulas (4) to (6), It is preferable that the electrophotographic photoreceptor has a protective layer containing at least one of these.
[0044]
Embedded image

[0045]
Where R ₆ , R ₇ And R ₈ Each represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched; ι, κ and λ each represent a halogen atom, an alkyl group which may have a substituent, or a substituent; An optionally substituted alkoxy group, an optionally substituted aryl group, or a benzene ring optionally having one or more heterocyclic groups, wherein a, b and d are 0 or Or 1 and s and t are 0 or 1.
[0046]
Embedded image

[0047]
Where R ₉ , R ₁₀ And R ₁₁ Represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched, and μ and ν each represent a halogen atom as a substituent, an alkyl group which may have a substituent, And a benzene ring which may have one or more of an optionally substituted alkoxy group, an optionally substituted aryl group or an optionally substituted heterocyclic group, wherein e, f and g are 0 or 1 It is. u, w, and v are 0 or 1, and they are not all 0 at the same time. Z ₁ And Z ₂ Represents a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. And may form a ring together.
[0048]
Embedded image

[0049]
Where R ₁₂ , R ₁₃ , R ₁₄ And R _Fifteen Represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched; ξ, π, ρ and σ each represent a halogen atom as a substituent, an alkyl group which may have a substituent, And a benzene ring which may have one or more of an alkoxy group which may have a substituent, an aryl group which may have a substituent or a heterocyclic group which may have a substituent, and h, i, j And k is 0 or 1, and x, y and z are 0 or 1. Z ₃ And Z ₄ Represents a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. And may form a ring together.
[0050]
The structures of the substituents in the above formulas (4) to (6) will be described in detail below.
[0051]
Where R ₆ ~ R _Fifteen Represents a divalent hydrocarbon group having 1 to 8 carbon atoms, which may be branched, such as a methylene group, an ethylene group, a propylene group, and butylene.
[0052]
In the formula, ι, κ, λ, μ, ν, ξ, π, ρ and σ, as the substituent which the benzene ring may have, include a halogen atom such as fluorine, chlorine, bromine and iodine, and a substituent. It may have an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an methoxy group that may have a substituent, an ethoxy group, an alkoxy group such as a propoxy group and a butoxy group, and a substituent. An aryl group such as a phenyl group, a naphthyl group, an anthryl group and a pyrenyl group, or a heterocyclic group such as a pyridyl group, a thienyl group, a furyl group and a quinolyl group which may have a substituent.
[0053]
Where Z ₁ ~ Z ₄ Is a halogen atom such as fluorine, chlorine, bromine and iodine, an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group which may have a substituent, a methoxy group and an ethoxy group which may have a substituent. An alkoxy group such as a propoxy group and a butoxy group, a phenyl group which may have a substituent, a naphthyl group, an aryl group such as an anthryl group and a pyrenyl group, or a pyridyl group which may have a substituent, a thienyl group, It represents a heterocyclic group such as a furyl group and a quinolyl group. Z ₁ And Z ₂ And Z ₃ And Z ₄ May jointly form a cyclic structure such as a fluorene skeleton or a dihydrophenanthrene skeleton through a biphenyl skeleton bonded to each other.
[0054]
In the formulas (4) to (6), examples of the substituent which may be present include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group; an aralkyl group such as a benzyl group, a phenethyl group and a naphthylmethyl group; Group, naphthyl group, anthryl group, pyrenyl group, fluorenyl group, carbazolyl group, aromatic ring group such as dibenzofuryl group and dibenzothiophenyl group, alkoxy group such as methoxy group, ethoxy group and propoxy group, phenoxy group and naphthoxy group etc. Aryloxy groups, halogen atoms such as fluorine, chlorine, bromine and iodine, nitro groups and cyano groups.
[0055]
The charge transporting material used in the present invention is preferably a triphenylamine derivative represented by any one of formulas (1) to (3) in order to further improve the compatibility and impart high charge transporting properties. R in formulas (4) to (6) ₆ ~ R _Fifteen The divalent hydrocarbon group represented by the formula (1) preferably has 4 or less carbon atoms, and more preferably has 2 or more hydroxyalkyl groups and hydroxyalkoxy groups. It is essential that the molecular weight is 250 or more and 800 or less, preferably 300 or more and 700 or less, and more preferably 350 or more and 650 or less.
[0056]
The charge transporting material used in the present invention is formed by uniformly dissolving or dispersing in a coating solution for producing a protective layer, and applying the solution. The mixing ratio of the charge transporting material and the thermosetting resin binder is preferably, in terms of mass ratio, charge transporting material / thermosetting resin binder = 0.1 / 10 to 20/10, more preferably 0.5 / 10 to 10/10. / 10. If the amount of the charge transporting material is too small relative to the thermosetting resin binder, the effect of lowering the residual potential is reduced.
[0057]
Hereinafter, specific examples of the charge transport material having at least one phenol group used in the present invention will be described. However, the charge transport material of the present invention is not limited to these.
[0058]
Embedded image

[0059]
Embedded image

[0060]
Embedded image

[0061]
Embedded image

[0062]
Embedded image

[0063]
Embedded image

[0064]
Embedded image

[0065]
Embedded image

[0066]
Embedded image

[0067]
Embedded image

[0068]
Embedded image

[0069]
Embedded image

[0070]
Embedded image

[0071]
Embedded image

[0072]
Embedded image

[0073]
Embedded image

[0074]
Embedded image

[0075]
Embedded image

[0076]
Embedded image

[0077]
Embedded image

[0078]
Embedded image

[0079]
Embedded image

[0080]
Embedded image

[0081]
Embedded image

[0082]
Further, specific examples of the charge transport material having at least one substituent selected from a hydroxyalkyl group and a hydroxyalkoxy group used in the present invention are shown below. However, the charge transport material of the present invention is not limited to these.
[0083]
Embedded image

[0084]
Embedded image

[0085]
Embedded image

[0086]
Embedded image

[0087]
Embedded image

[0088]
Embedded image

[0089]
Embedded image

[0090]
Embedded image

[0091]
Embedded image

[0092]
Embedded image

[0093]
Embedded image

[0094]
Embedded image

[0095]
Embedded image

[0096]
Embedded image

[0097]
Embedded image

[0098]
Embedded image

[0099]
Embedded image

[0100]
Embedded image

[0101]
Embedded image

[0102]
Embedded image

[0103]
Embedded image

[0104]
Embedded image

[0105]
Embedded image

[0106]
Embedded image

[0107]
The protective layer may contain one or both of inorganic fine particles and organic fine particles, and as the fine particles, conductive particles having a resistance adjusting function of the protective layer are preferable, and from the wear resistance of the protective layer, Lubricious particles are preferred.
[0108]
In the present invention, conductive particles may be used as having an auxiliary role of adjusting the volume resistivity of the protective layer. Examples include metals, metal oxides and carbon black. Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver, stainless steel, and the like, and those obtained by vapor-depositing these metals on the surfaces of plastic particles. Metal oxides include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, alumina oxide, tin-doped indium oxide, antimony and tantalum-doped tin oxide, and antimony-doped zirconium oxide. Is mentioned. These can be used alone or in combination of two or more. When two or more kinds are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion.
[0109]
In the present invention, among the above-described conductive particles, it is preferable to use a metal oxide from the viewpoint of transparency. Further, among these metal oxides, it is particularly preferable to use tin oxide. Tin oxide may be subjected to a surface treatment described below for the purpose of improving dispersibility and liquid stability, and may be doped with antimony or tantalum for the purpose of improving resistance controllability.
[0110]
Some of the above-mentioned metals and metal oxides also have an effect of reducing the amount of shaving of the protective layer by being included in the protective layer.
[0111]
The protective layer used in the present invention does not essentially transfer electric charge as a resistor, but transfers an electric charge by using a charge transporting material contained in the protective layer to form an electrophotographic photosensitive member provided with the protective layer. Is maintained, and the residual potential is reduced. Therefore, it is not necessary to set the volume resistivity as a resistor low, and the volume resistivity is 1 × 10 ¹² By setting the resistance to Ω · cm or more, the flow of the formed electrostatic latent image can be suppressed at a high level.
[0112]
The conductive fine particles according to the present invention play an auxiliary role of adjusting the volume resistivity of the protective layer, and may not necessarily be used if not necessary.
[0113]
In terms of film strength, as the amount of the conductive particles increases, the film becomes weaker. Therefore, it is preferable to reduce the amount of the conductive particles as long as the volume resistance and the residual potential of the protective layer are acceptable.
[0114]
In the present invention, fluorine atom-containing resin particles may be included in order to improve the lubricity of the protective layer. Examples include tetrafluoroethylene, ethylene trifluoride ethylene resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin and copolymers thereof. It is preferable to appropriately select one or more kinds, and particularly preferable are a tetrafluoroethylene resin and a vinylidene fluoride resin. The molecular weight distribution and the particle size of the resin particles can be appropriately selected and are not particularly limited.
[0115]
The average particle size of the conductive or lubricating fine particles used in the present invention is preferably 0.005 to 3 μm. Further, it is preferably 0.3 μm or less, particularly preferably 0.1 μm or less from the viewpoints of transparency, film thickness, curability and the like of the protective layer.
[0116]
The fluorine atom-containing resin particles are added together with the conductive particles together with the conductive particles in the resin solution, so that a fluorine atom-containing compound is added at the time of dispersion of the conductive particles, or the surface of the conductive particles is fluorine atom-containing. Surface treatment with a compound is preferred. By adding a fluorine atom-containing compound or performing a surface treatment on the conductive particles, the dispersibility and dispersion stability of the conductive particles and the fluorine atom-containing resin particles in the resin solution are reduced as compared to the case without the fluorine atom-containing compound. Has improved significantly. Further, the formation of secondary particles of dispersed particles by dispersing fluorine atom-containing resin particles in a liquid in which conductive particles are dispersed by adding a fluorine atom-containing compound, or in a liquid in which conductive particles subjected to surface treatment are dispersed. No coating liquid is obtained which is very stable and has good dispersibility over time.
[0117]
Examples of the fluorine atom-containing compound in the present invention include a fluorine-containing silane coupling agent, a fluorine-modified silicone oil, and a fluorine-based surfactant. Preferred examples of the compounds are shown below in Tables 1 to 3, but the present invention is not limited to these compounds.
[0118]
[Table 1]

[0119]
[Table 2]

[0120]
[Table 3]

[0121]
As a surface treatment method for the conductive particles, the conductive particles and the surface treatment agent are mixed and dispersed in an appropriate solvent, and the surface treatment agent is attached to the surface of the conductive particles. As a dispersion method, a usual dispersion means such as a ball mill or a sand mill can be used. Next, the solvent may be removed from the dispersion solution and fixed to the surface of the conductive particles. If necessary, heat treatment may be further performed thereafter. Further, a catalyst for promoting the reaction can be added to the treatment liquid. Further, if necessary, the conductive particles after the surface treatment can be further subjected to a pulverizing treatment.
[0122]
The ratio of the fluorine atom-containing compound to the conductive particles is affected by the particle size, shape, surface area, and the like of the particles, but is preferably 1 to 65% by mass, more preferably, to the total mass of the surface-treated conductive particles. 1 to 50% by mass.
[0123]
Further, in the present invention, in order to make the protective layer more environmentally stable, a siloxane compound represented by the following formula (7) is added at the time of dispersion of the conductive particles, or represented by the following formula (7). By mixing the conductive particles subjected to the surface treatment with the siloxane compound, a protective layer having more excellent environmental stability can be obtained.
[0124]
Embedded image

[0125]
In the formula, A is a hydrogen atom or a methyl group, and the proportion of hydrogen atoms in all A is in the range of 0.1 to 50%, and n is an integer of 0 or more.
[0126]
By dispersing the coating liquid in which the siloxane compound is added and then dispersed, or the conductive metal oxide fine particles whose surface has been treated in a binder resin dissolved in a solvent, no secondary particles of dispersed particles are formed. Thus, a coating liquid having good dispersibility, which is stable over time, can be obtained. Further, a protective layer formed from this coating liquid has high transparency, and a film having particularly excellent environmental resistance can be obtained.
[0127]
The molecular weight of the siloxane compound represented by the formula (7) is not particularly limited, but when the surface treatment is performed, it is better not to have a too high viscosity because of its easiness. About ten thousand is appropriate.
[0128]
There are two types of surface treatment, wet and dry. In the wet method, the conductive metal oxide particles are dispersed in a solvent with a siloxane compound represented by the formula (7), and the siloxane compound is attached to the surface of the fine particles. As the dispersing means, general dispersing means such as a ball mill and a sand mill can be used. Next, this dispersion solution is fixed to the surface of the conductive metal oxide fine particles.
[0129]
In this heat treatment, the Si—H bonds in the siloxane undergo oxidation of hydrogen atoms by oxygen in the air during the heat treatment process, so that a new siloxane bond is formed. As a result, the siloxane develops to a three-dimensional structure, and the surface of the conductive metal oxide fine particles is covered with this network structure. Thus, the surface treatment is completed by fixing the siloxane compound on the surface of the conductive metal oxide fine particles. However, the fine particles after the treatment may be subjected to a pulverizing treatment, if necessary. In the dry treatment, the siloxane compound is attached to the surface of the fine particles by mixing and kneading the siloxane compound and the conductive metal oxide fine particles without using a solvent. After that, heat treatment or pulverization treatment is performed in the same manner as the wet treatment to complete the surface treatment.
[0130]
As a solvent for dispersing the coating liquid for the protective layer, the thermosetting resin is well dissolved, the charge transport material is also well dissolved, and when the conductive fine particles are used, the dispersibility is good, and the fluorine atom-containing compound is further used. When a fluorine atom-containing resin particle or a siloxane compound is used, a solvent which has good compatibility and processability and which does not adversely affect the charge transport layer which comes into contact with the coating liquid for the protective layer is preferable.
[0131]
Therefore, as the solvent, alcohols such as methanol, ethanol and 2-propanol, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, ethers such as tetrahydrofuran and dioxane, and aromatics such as toluene and xylene Aromatic hydrocarbons, halogenated hydrocarbons such as chlorobenzene, dichloromethane and the like can be used, and these may be used as a mixture. Among these, the most suitable solvents for the form of the thermosetting resin are alcohols such as methanol, ethanol and 2-propanol.
[0132]
As a method for applying the protective layer of the present invention, general coating methods such as dip coating, spray coating, spinner coating, roller coating, Meyer bar coating, and blade coating can be used.
[0133]
If the thickness of the protective layer of the present invention is too small, the durability of the electrophotographic photoreceptor is impaired. If the thickness is too large, the residual potential due to the provision of the protective layer increases. Specifically, the range is preferably from 0.1 μm to 10 μm, and more preferably from 0.5 μm to 7 μm.
[0134]
In the present invention, an additive of an antioxidant may be added to the protective layer for the purpose of preventing the surface layer from deteriorating due to adhesion of an active substance such as ozone or NOx generated during charging.
[0135]
Next, the photosensitive layer will be described below.
[0136]
The electrophotographic photoreceptor of the present invention preferably has a mainly laminated structure. In the electrophotographic photoreceptor of FIG. 1A, a charge generation layer 3 and a charge transport layer 2 are sequentially provided on a conductive support 4, and a protective layer 1 is further provided on the outermost surface. As shown in FIGS. 1B and 1C, a binder layer 5 and an undercoat layer 6 for preventing interference fringes or the like may be provided between the conductive support and the charge generation layer. .
[0137]
As the conductive support 4, a support having conductivity itself, for example, a metal such as aluminum, an aluminum alloy, and stainless steel can be used. In addition, aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like can be used in vacuum. The conductive support or plastic having a layer formed by vapor deposition, a support in which conductive fine particles (for example, carbon black, tin oxide, titanium oxide and silver particles, etc.) are impregnated with a suitable binder into plastic or paper, A plastic or the like having a conductive binder can be used. However, in the present invention, the diameter is less than φ30 mm.
[0138]
Further, a binding layer (adhesive layer) having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. The binder layer is used for improving the adhesiveness of the photosensitive layer, improving the coating properties, protecting the support, covering defects of the support, improving the charge injection property from the support, and protecting the photosensitive layer against electrical breakdown. It is formed. The binding layer can be formed of casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The thickness of the binder layer is preferably 5 μm or less, more preferably 0.1 to 3 μm.
[0139]
Examples of the charge generating material used in the present invention include (1) azo pigments such as monoazo, disazo and trisazo, (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, and (3) indigo pigments such as indigo and thioindigo. Pigments, (4) perylene pigments such as perylene anhydride and perylene imide, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, (6) squarylium dyes, (7) pyrylium salts and thiapyrylium salts, ( 8) triphenylmethane dyes, (9) inorganic substances such as selenium, selenium-tellurium and amorphous silicon, (10) quinacridone pigments, (11) azulhenium salt pigments, (12) cyanine dyes, (13) xanthene dyes, 14) quinone imine dye, (15) styryl dye, (16) potassium sulfide Miumu and (17) zinc oxide.
[0140]
As the binder resin used for the charge generation layer, for example, polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples include, but are not limited to, silicone resins, polysulfone resins, styrene-butadiene copolymer resins, alkyd resins, epoxy resins, urea resins, and vinyl chloride-vinyl acetate copolymer resins. These can be used alone, as a mixture or as one or more of them as a copolymer polymer.
[0141]
The solvent used for the charge generation layer coating liquid is selected from the solubility and dispersion stability of the resin and the charge generation material used. As the organic solvent, alcohols, sulfoxides, ketones, ethers, and esters are used. And aliphatic halogenated hydrocarbons or aromatic compounds.
[0142]
The charge generating layer 3 sufficiently disperses the above charge generating material together with a binder resin and a solvent in an amount of 0.3 to 4 times by a method such as a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, and a roll mill, It is formed by coating and drying. The thickness is preferably 5 μm or less, particularly preferably in the range of 0.01 to 1 μm.
[0143]
In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers and known charge generation materials can be added to the charge generation layer as needed.
[0144]
Examples of charge transport materials used include various triarylamine compounds, various hydrazone compounds, various styryl compounds, various stilbene compounds, various pyrazoline compounds, various oxazole compounds, various thiazole compounds, and various triarylmethane compounds. And the like.
[0145]
Examples of the binder resin used to form the charge transport layer 2 include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. Resins selected from are preferred. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin and diallyl phthalate resin.
[0146]
The charge transport layer 2 is generally formed by dissolving the above-described charge transport material and binder resin in a solvent and applying the resulting solution. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. Examples of the solvent include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride. Can be When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, and a spinner coating method can be used, and the drying is performed at a temperature of 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C. For 5 minutes to 5 hours, preferably 10 minutes to 2 hours, and can be performed under blast drying or still drying.
[0147]
The charge transport layer is electrically connected to the above-described charge generation layer, receives charge carriers injected from the charge generation layer in the presence of an electric field, and transports these charge carriers to the interface with the protective layer. It has the function to do. The thickness of the charge transport layer cannot be increased more than necessary because there is a limit for transporting charge carriers. However, the thickness is preferably 5 to 40 μm, and particularly preferably 7 to 30 μm.
[0148]
Further, an antioxidant, an ultraviolet absorber, a plasticizer, or a known charge transport material can be added to the charge transport layer as needed.
[0149]
The present invention is further completed by coating and curing the protective layer on the charge transport layer to form a film.
[0150]
FIG. 2 shows a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.
[0151]
In FIG. 2, reference numeral 11 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is driven to rotate around an axis 12 in a direction of an arrow at a predetermined peripheral speed. The electrophotographic photoreceptor 11 receives a uniform charge of a predetermined positive or negative potential on its peripheral surface by the primary charging means 13 during the rotation process, and then receives light from exposure means (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 14 is intensity-modulated according to a time-series electric digital image signal of target image information to be output. In this way, an electrostatic latent image corresponding to the target image information is sequentially formed on the peripheral surface of the electrophotographic photosensitive member 11.
[0152]
The formed electrostatic latent image is then developed with toner by a developing unit 15 and taken out from a paper feeding unit (not shown) between the electrophotographic photoconductor 11 and the transfer unit 16 in synchronization with the rotation of the electrophotographic photoconductor 11. The toner images formed and carried on the surface of the electrophotographic photosensitive member 11 are sequentially transferred by the transfer means 16 to the transfer material 17 fed and fed.
[0153]
The transfer material 17 to which the toner image has been transferred is separated from the surface of the electrophotographic photoreceptor, introduced into the image fixing means 18 and subjected to image fixing to be printed out as an image formed product (print, copy) outside the apparatus. .
[0154]
The surface of the electrophotographic photoreceptor 11 after the image transfer is cleaned and cleaned by removing the untransferred toner by a cleaning unit 19, and further subjected to a charge removal process by a pre-exposure light 20 from a pre-exposure unit (not shown). , Is repeatedly used for image formation. When the primary charging means 13 is a contact charging means using a charging roller or the like, pre-exposure is not always necessary.
[0155]
In the present invention, among the above-described components such as the electrophotographic photoreceptor 11, the primary charging unit 13, the developing unit 15, and the cleaning unit 19, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 13, the developing unit 15, and the cleaning unit 19 is integrally supported with the electrophotographic photosensitive member 11 to form a cartridge, and the cartridge is attached to and detached from the apparatus main body using the guide means 22 such as a rail of the apparatus main body. A flexible process cartridge 21 can be provided.
[0156]
When the electrophotographic apparatus is a copying machine or a printer, the exposure light 14 is reflected light or transmitted light from the original, or the original is read by a sensor, converted into a signal, and scanned by a laser beam performed in accordance with the signal. , Light emitted by driving an LED array or driving a liquid crystal shutter array.
[0157]
The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, faxes, liquid crystal printers, and laser plate making. It is.
[0158]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples. However, embodiments of the present invention are not limited to these. In the examples, “parts” means “parts by mass”.
[0159]
(Example 1)
Using an aluminum cylinder (JIS A3003 aluminum alloy) having a length of 246 mm and a diameter of 24 mm as a support, a 5% by mass methanol solution of a polyamide resin (trade name: Amilan CM8000, manufactured by Toray Co., Ltd.) was applied thereto by dipping. Provided a 0.5 μm undercoat layer.
[0160]
Next, oxytitanium which is a crystal type having strong peaks at 9.6 ° and 27.2 ° of Bragg angles (2θ ± 0.2 °) in characteristic X-ray diffraction of CuKα represented by the following formula as a charge generation material: 4 parts of phthalocyanine pigment,
[0161]
Embedded image

Two parts of polyvinyl butyral resin BX-1 (manufactured by Sekisui Chemical Co., Ltd.) and 110 parts of cyclohexanone were dispersed in a sand mill using φ1 mm glass beads for 4.5 hours. Thereafter, the resultant was diluted with 130 parts of ethyl acetate to obtain a coating liquid for a charge generation layer. The coating liquid was applied onto the undercoat layer by a dipping method to form a charge generation layer having a thickness of 0.18 μm.
[0162]
Next, 7.5 parts of a charge transport material represented by the following formula,
[0163]
Embedded image

And 10 parts of bisphenol Z-type polycarbonate (trade name: Z-200, manufactured by Mitsubishi Gas Chemical) were dissolved in 60 parts of monochlorobenzene / 20 parts of dichloromethane. This solution was dip-coated on the charge generation layer and dried with hot air at 110 ° C. for 1 hour to form a charge transport layer having a thickness of 15 μm.
[0164]
Next, as a resin component as a protective layer, 54 parts of resole type curable phenol resin (trade name: PR-53123, manufactured by Sumitomo Durez Co., Ltd.) (nonvolatile content: 45%), and an example of a compound having a phenol group as a charge transport material No. 15 parts of 1-14 (molecular weight: 541.72) are dissolved, and further, polytetrafluoroethylene fine particles (average particle diameter: 0.18 μm, measured by a particle size distribution meter (product name: CAPA700, HORIBA, Ltd.)) and 18 parts are added. Then, the resultant was diluted with 35 parts of acetone to obtain a coating liquid for a protective layer. Using this coating solution, a film was formed on the charge transport layer by dip coating, and then dried with hot air at 145 ° C. for 1 hour to form a protective layer having a thickness of 2 μm.
[0165]
(Example 2)
In Example 1, the curable resin for the protective layer was 45 parts of an acrylic polyol resin (trade name: Acrydic A-801P, nonvolatile content: 50%, Dainippon Ink and Chemicals, Inc.), and blocked isocyanate (trade name: Burnock) An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that DN995, a nonvolatile content of 75%, and Dainippon Ink and Chemicals, Inc.) were used in 7 parts.
[0166]
(Example 3)
In Example 1, the curable resin of the protective layer was 21 parts of a thermosetting epoxy resin represented by the following formula,
[0167]
Embedded image

Further, 4.9 parts of an acid anhydride represented by the following formula is used as a curing catalyst.
[0168]
Embedded image

An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that was added.
[0169]
(Example 4)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a hydrazone-based compound represented by the following formula. The molecular weight of this charge transporting material was 492.76.
[0170]
Embedded image

[0171]
(Example 5)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a styryl compound represented by the following formula. The molecular weight of this charge transporting material was 528.1.
[0172]
Embedded image

[0173]
(Example 6)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a triarylamine compound represented by the following formula. The molecular weight of this charge transporting material was 498.8.
[0174]
Embedded image

[0175]
(Example 7)
In Example 1, the charge transporting material of the protective layer was changed to Compound Example No. An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the composition was changed to 4-23. The molecular weight of this charge transporting material was 361.48.
[0176]
(Example 8)
A charge transport layer was formed in the same manner as in Example 1.
[0177]
The protective layer was surface-treated with 100 parts of antimony-doped tin oxide fine particles with 7 parts of a fluorine atom-containing compound represented by the following formula (trade name: LS-1090, manufactured by Shin-Etsu Silicone Co., Ltd.) (treatment amount: 7%). 35 parts of tin oxide fine particles
[0178]
Embedded image

Ethanol (150 parts) was dispersed in a sand mill for 66 hours, and 18 parts of polytetrafluoroethylene fine particles (average particle size: 0.18 μm) were further added. The mixture was further dispersed in a sand mill for 12 hours.
[0179]
Thereafter, as a resin component, 54 parts of resole type curable phenol resin (trade name: PR-53123, manufactured by Sumitomo Durez Co., Ltd.) (nonvolatile content: 45%), and further, as a charge transport material having a hydroxyalkyl group, Compound Example No. . 4-23 was dissolved in 15 parts and diluted with 35 parts of ethanol to obtain a coating liquid for a protective layer. Using this coating solution, a film was formed on the charge transport layer by dip coating, and then dried with hot air at 145 ° C. for 1 hour to form a protective layer having a thickness of 2 μm.
[0180]
(Example 9)
An electrophotographic photosensitive member was produced in the same manner as in Example 7, except that the thermosetting resin was the urethane resin of Example 2.
[0181]
(Example 10)
An electrophotographic photosensitive member was produced in the same manner as in Example 7, except that the same epoxy resin and curing catalyst as in Example 3 were added to the thermosetting resin.
[0182]
(Example 11)
In Example 7, the curable resin was 20 parts of an acrylic resin (neopentyl glycol-modified trimethylolpropane diacrylate, trade name: Karayad R-604, manufactured by Nippon Kayaku) represented by the following formula,
[0183]
Embedded image

Further, as an initiator, 4 parts of benzoin represented by the following formula (trade name: Nissocure MB, Nippon Soda),
[0184]
Embedded image

4 parts of a benzophenone-based energy transfer agent (2,2'dichloro-4,4'-dihydroxybenzophenone) represented by the following formula
[0185]
Embedded image

Was added to provide a coating liquid for a protective layer. Next, after forming a film on the previous charge transport layer by a dip coating method, 160 W / cm was applied with a high-pressure mercury lamp. ² UV light having a light intensity of 320 nm or less was irradiated for 30 seconds to perform photocuring, followed by drying with hot air at 100 ° C. for 1 hour to form a protective layer. The film thickness obtained at this time was 2 μm.
[0186]
(Example 12)
In Example 7, the curable resin was a thermosetting silicone resin (trade name: Tosgard 510, manufactured by Toshiba Silicone Co., Ltd.) mainly containing a hydrolysis-condensation product of trialkoxysilane and tetraalkoxysilane.
[0187]
(Example 13)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the composition was changed to 4-2. The molecular weight of the charge transport material was 289.15.
[0188]
(Example 14)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 2-1 was used. The molecular weight of the charge transport material was 337.15.
[0189]
(Example 15)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 4-7 was used. The molecular weight of the charge transport material was 319.16.
[0190]
(Example 16)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 6-6 was used. The molecular weight of the charge transporting material was 664.33.
[0191]
(Example 17)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 6-8 was used. The molecular weight of the charge transport material was 728.31.
[0192]
(Example 18)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 6-22 was used. The molecular weight of the charge transport material was 760.42.
[0193]
(Example 19)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 2-19 was used. The molecular weight of the charge transporting material was 405.21.
[0194]
(Example 20)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 3-2 was used. The molecular weight of the charge transport material was 443.19.
[0195]
(Example 21)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the photosensitive material was changed to 5-22. The molecular weight of the charge transport material was 501.22.
[0196]
(Example 22)
In Example 1, the charge transporting material of the protective layer was No. 1; An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 6-16 was used. The molecular weight of the charge transport material was 618.29.
(Comparative Example 1)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a compound represented by the following formula. The molecular weight of this charge transport material was 197.27.
[0197]
Embedded image

[0198]
(Comparative Example 2)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a compound represented by the following formula. The molecular weight of this charge transporting material was 852.32.
[0199]
Embedded image

[0200]
(Comparative Example 3)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the charge transport material of the protective layer was a compound represented by the following formula. The molecular weight of this charge transporting material was 871.41.
[0201]
Embedded image

[0202]
(Comparative Example 4)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the charge transport material was not added to the protective layer.
[0203]
The electrophotographic photosensitive member produced as described above was evaluated by the following method. The evaluation of the electrophotographic characteristics was performed by attaching to a laser beam printer (trade name: LBP-350, manufactured by Canon Inc.). As the electrophotographic sensitivity, the charging was set so that the dark area potential was -700 V, and a laser beam having a wavelength of 780 nm was irradiated to this, and the amount of light required to reduce the potential of -700 V to -200 V was measured and defined as the sensitivity. . Furthermore, 20 μJ / cm ² Was measured as the residual potential Vr. The potential was measured using a cartridge modified so that a probe of a surface voltmeter could be attached to the developing sleeve. Further, the light amount was converted into the light amount after measuring the voltage by directing the photocell connected to the digivol in the direction in which the laser light was emitted. Table 4 shows the results.
[0204]
Further, using the same laser beam printer, the shaving amount and the image evaluation due to the durability of 2500 sheets were measured. The measurement was performed in two environments: low temperature and low humidity (10 ° C./10% RH) and high temperature and high humidity (30 ° C./85% RH). Table 5 shows the results.
[0205]
The evaluation of scratch resistance was performed by the following method. A diamond needle having a diameter of 0.1 mm is brought into contact with the surface of the electrophotographic photosensitive member. Next, after a load is placed on the needle, the electrophotographic photoreceptor is rotated once at a peripheral speed of 5 mm / sec to generate a scratch on the electrophotographic photoreceptor. The same flaw is generated by changing the load, and the depth of the flaw is measured by a surface roughness meter or the like, and the degree of each electrophotographic photosensitive member relative to the flaw is determined. Table 6 shows the results.
[0206]
For severe storage, the electrophotographic photoreceptors of Examples and Comparative Examples prepared as described above were mounted on an LBP-350 cartridge and left for 90 days in an environment of 50 ° C./95% RH. The surface of the photoreceptor and the obtained image were visually observed. Table 7 shows the results.
[0207]
[Table 4]

[0208]
[Table 5]

[0209]
[Table 6]

[0210]
[Table 7]

[0211]
【The invention's effect】
As described above, according to the present invention, by providing a protective layer on an electrophotographic photoreceptor, it is possible to efficiently suppress a decrease in sensitivity and a rise in residual potential, which are problems, and are excellent against abrasion and scratches. It has become possible to provide an electrophotographic photoreceptor which can maintain high quality image quality without causing toner filming and image bleeding due to adhesion of a developer to the surface. Further, it has become possible to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a layer structure of an electrophotographic photoreceptor of the present invention.
FIG. 2 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member of the present invention.
[Explanation of symbols]
1 protective layer
2 Charge transport layer
3 charge generation layer
4 Conductive support
5 Binding layer
6 Undercoat layer
11 Electrophotographic photoreceptor
12 axes
13 Charging means
14 Exposure light
15 Developing means
16 transfer means
17 Transfer material
18 Fixing means
19 Cleaning means
20 Pre-exposure light
21 Process cartridge
22 Guidance means

Claims (7)

In an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer on a conductive support, the conductive support has a diameter of less than 30 mm, and the protective layer contains at least a curable resin and a charge transport material. An electrophotographic photoreceptor, wherein the charge transport material has a molecular weight of 250 or more and 800 or less. The electrophotographic photoreceptor according to claim 1, wherein the charge transport material has a molecular weight of 300 or more and 700 or less. 3. The electrophotographic photosensitive member according to claim 2, wherein the charge transport material has a molecular weight of 350 or more and 650 or less. The electrophotographic photosensitive member according to claim 1, wherein the curable resin is at least one selected from the group consisting of a phenol resin, an epoxy resin, an acrylic resin, a siloxane resin, and a urethane resin. The electrophotographic photosensitive member according to claim 3, wherein the phenol resin is a resol type phenol resin. A charging unit for charging the electrophotographic photosensitive member according to claim 1, a developing unit for developing the electrophotographic photosensitive member on which an electrostatic latent image is formed with toner, and a transfer step. A process cartridge which is integrally supported together with at least one means selected from the group consisting of a cleaning means for recovering toner remaining on an electrophotographic photosensitive member, and is detachable from an electrophotographic apparatus main body. An electrophotographic photosensitive member according to any one of claims 1 to 5, a charging device for charging the electrophotographic photosensitive member, an exposure device for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, and an electrostatic device. An electrophotographic apparatus, comprising: developing means for developing a latent image on an electrophotographic photosensitive member with toner; and transfer means for transferring a toner image on the electrophotographic photosensitive member onto a transfer material.

Images