JP2004226770A - Electrophotographic photoreceptor and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent wear and scuffing resistances and image stability in long-term use, and to provide an image forming apparatus, a process cartridge, and an image forming method using those. <P>SOLUTION: In the electrophotographic photoreceptor having at least a photosensitive layer and a surface protection layer on a conductive support, the surface protection layer comprises a urethane resin obtained by crosslinking polymerization of at least an isocyanate and a polyol and a polymeric charge transport material, and the polymeric charge transport material is a polymer of a polycarbonate having a triphenylamine skeleton in a backbone and/or on a side chain. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

（式中、Ｒは水素原子、炭素数１〜５のアルキル基を表わし、ｎ＝１〜５である。）」、（４）「前記ポリオールの分子量が、１００以上１５０以下であることを特徴とする前記第（３）項に記載の電子写真感光体」、（５）「前記高分子電荷輸送物質として下記一般式１で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（４）項のいずれかに記載の電子写真感光体；
【００１７】
【化１５】

式中、Ｒ_１，Ｒ_２，Ｒ_３はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ_４は水素原子又は置換もしくは無置換のアルキル基、Ｒ_５，Ｒ_６は置換もしくは無置換のアリール基、ｏ，ｐ，ｑはそれぞれ独立して０〜４の整数、ｋ，ｊは組成を表わし、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表わし、５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表わされる２価基を表わす。
【００１８】
【化１６】

式中、Ｒ_１０１，Ｒ_１０２は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表わす。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−，−Ｓ−，−ＳＯ−，−ＳＯ_２−，−ＣＯ−，−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表わす。）または、
【００１９】
【化１７】

（式中、ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換または無置換のアルキル基又はアリール基を表わす。）を表わす。ここで、Ｒ_１０１とＲ_１０２，Ｒ_１０３とＲ_１０４は、それぞれ同一でも異なってもよい。」、（６）「前記高分子電荷輸送物質として下記一般式２で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（５）項のいずれかに記載の電子写真感光体；
【００２０】
【化１８】

式中、Ｒ_７，Ｒ_８は置換もしくは無置換のアリール基、Ａｒ_１，Ａｒ_２，Ａｒ_３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。」、（７）「前記高分子電荷輸送物質として下記一般式３で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（６）項のいずれかに記載の電子写真感光体；
【００２１】
【化１９】

式中、Ｒ_９，Ｒ_１０は置換もしくは無置換のアリール基、Ａｒ_４，Ａｒ_５，Ａｒ_６ は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（８）「前記高分子電荷輸送物質として、下記一般式４で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（７）項のいずれかに記載の電子写真感光体；
【００２２】
【化２０】

式中、Ｒ_１１，Ｒ_１２は置換もしくは無置換のアリール基、Ａｒ_７，Ａｒ_８，Ａｒ_９は同一又は異なるアリレン基、ｓは１〜５の整数を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（９）「前記高分子電荷輸送物質として、下記一般式５で表わされるトリアリールアミン構造を主鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（８）項のいずれかに記載の電子写真感光体；
【００２３】
【化２１】

式中、Ｒ_１３，Ｒ_１４は置換もしくは無置換のアリール基、Ａｒ_１０，Ａｒ_１１，Ａｒ_１２は同一又は異なるアリレン基、Ｘ_１，Ｘ_２は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１０）「前記高分子電荷輸送物質として、下記一般式６で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（９）項のいずれかに記載の電子写真感光体；
【００２４】
【化２２】

式中、Ｒ_１５，Ｒ_１６，Ｒ_１７，Ｒ_１８は置換もしくは無置換のアリール基、Ａｒ_１３，Ａｒ_１４，Ａｒ_１５，Ａｒ_１６は同一又は異なるアリレン基、Ｙ_１，Ｙ_２，Ｙ_３は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わし、同一であっても異なってもよい。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１１）「前記高分子電荷輸送物質として、下記一般式７で表わされるトリアリールアミン構造を主鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（１０）項のいずれかに記載の電子写真感光体；
【００２５】
【化２３】

式中、Ｒ_１９，Ｒ_２０は水素原子、置換もしくは無置換のアリール基を表わし、Ｒ_１９とＲ_２０は環を形成していてもよい。Ａｒ_１７，Ａｒ_１８，Ａｒ_１９は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１２）「前記高分子電荷輸送物質として、下記一般式８で表わされるトリアリールアミン構造を主鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（１１）項のいずれかに記載の電子写真感光体；
【００２６】
【化２４】

式中、Ｒ_２１は置換もしくは無置換のアリール基、Ａｒ_２０，Ａｒ_２１，Ａｒ_２２，Ａｒ_２３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１３）「前記高分子電荷輸送物質として、下記一般式９で表わされるトリアリールアミン構造を分岐鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（１２）項のいずれかに記載の電子写真感光体；
【００２７】
【化２５】

式中、Ｒ_２２，Ｒ_２３，Ｒ_２４，Ｒ_２５は置換もしくは無置換のアリール基、Ａｒ_２４，Ａｒ_２５，Ａｒ_２６，Ａｒ_２７，Ａｒ_２８は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１４）「前記高分子電荷輸送物質として、下記一般式１０で表わされるトリアリールアミン構造を主鎖に有するポリカーボネートを含有することを特徴とする前記第（１）項乃至第（１３）項のいずれかに記載の電子写真感光体；
【００２８】
【化２６】

式中、Ｒ_２６，Ｒ_２７は置換もしくは無置換のアリール基、Ａｒ_２９，Ａｒ_３０，Ａｒ_３１は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである」、（１５）「前記表面保護層膜厚が、１．０〜８．０μｍであることを特徴とする前記第（１）項乃至第（１４）項のいずれかに記載の電子写真感光体」によって解決される。
【００２９】
また、上記課題は、本発明の（１６）「少なくとも帯電手段、画像露光手段、現像手段、転写手段および電子写真感光体を具備してなる画像形成装置において、該電子写真感光体として、前記第（１）項乃至第（１５）項のいずれかに記載の電子写真感光体を用いたことを特徴とする画像形成装置」、（１７）「前記画像露光手段のＬＤあるいはＬＥＤ等を使用することによって感光体上に静電潜像の書き込みが行なわれることを特徴とする前記第（１６）項に記載の画像形成装置」、（１８）「前記帯電手段が帯電部材を感光体に接触もしくは近接配置したものであることを特徴とする前記第（１６）項又は第（１７）項に記載の画像形成装置」、（１９）「前記帯電部材の直流成分に交流成分を重畳し、感光体に帯電を与えることを特徴とする前記第（１６）項乃至第（１８）項のいずれかに記載の画像形成装置」によって解決される。
【００３０】
また、上記課題は、本発明の（２０）「少なくとも、帯電手段、露光手段、現像手段、転写手段、クリーニング手段、除電手段のいずれか一つと電子写真感光体を一体化したプロセスカートリッジにおいて、該電子写真感光体が前記第（１）項乃至第（１５）項のいずれかに記載の電子写真感光体であることを特徴とするプロセスカートリッジ」によって解決される。
【００３１】
また、上記課題は、本発明の（２１）「少なくとも帯電手段、画像露光手段、現像手段、転写手段および前記第（１）項乃至第（１５）項のいずれかに記載の電子写真感光体を用いたことを特徴とする画像形成方法」によって解決される。
【００３２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
導電性支持体上に少なくとも感光層及び表面保護層を有する電子写真感光体において、該表面保護層が少なくともイソシアネートとポリオールを架橋重合したウレタン樹脂と高分子電荷輸送材料を含有し、該高分子電荷輸送材料がトリフェニルアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体であることを特徴とする電子写真感光体とする。
表面保護層を上記構造の膜とすることにより、長期的使用における感光体の耐摩耗性及び静電特性が向上し、画像安定性に優れた電子写真感光体、画像形成装置、プロセスカートリッジ、画像形成方法を提供することができる。
【００３３】
イソシアネートとポリオールを架橋重合したウレタン樹脂は、機械的耐久性に優れる。しかし、このウレタン樹脂は、電荷輸送機能がないために、２μｍ以下の薄膜の保護層としては使用できるが、さらに耐久性を維持するために厚膜化が不可能であった。
このウレタン樹脂に電荷輸送機能を付与する方法としては、従来技術でも挙げた電荷輸送物質を添加する方法がある。しかし、これらの電荷輸送物質を添加する方法では、ウレタン樹脂本来の機械的耐久性低下が発生した。
一方、トリアリールアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体である高分子電荷輸送材料は、低分子電荷輸送材料を結着樹脂中に分散した膜に比べて、機械的耐久性は向上するが、今後望まれているさらなる高耐久化に対して充分ではない。
【００３４】
そこで、本発明のウレタン樹脂とトリアリールアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体である高分子電荷輸送材料を混合した表面保護層とすることにより、本来のウレタン樹脂が持つ膜の弾性及び強靱性を低下させることなく、機械的耐久性が良好であり、且つ静電特性が向上した表面保護層とすることが可能となった。
これは、機械的耐久性の高く、電荷輸送機能を有するトリアリールアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体である高分子電荷輸送材料樹脂鎖を覆い絡まるようにして、ウレタン樹脂の３次元ネットワークが形成されるために、ウレタン樹脂本来の機械的耐久性低下がなく、良好な電荷輸送機能と有する表面保護層となる。
【００３５】
以下、本発明に用いられる電子写真感光体を図面に沿って説明する。
図１は、本発明の電子写真感光体の構成例を示す断面図であり、導電性支持体上に、電荷発生材料と電荷輸送材料を主成分とする単層感光層が設けられ、更に感光層上に表面保護層が設けられてなる。
【００３６】
図２は、本発明の電子写真感光体の別の構成例を示す断面図であり、導電性支持体上に、電荷発生材料を主成分とする電荷発生層と電荷輸送材料を主成分とする電荷輸送層とが積層された構成をとっており、更に電荷輸送層上に表面保護層が設けられてなる。
【００３７】
図３は、本発明の電子写真感光体の別の構成例を示す断面図であり、導電性支持体上に、下引き層が設けられ、その上に電荷発生材料を主成分とする電荷発生層と電荷輸送材料を主成分とする電荷輸送層とが積層された構成をとっており、更に電荷輸送層上に表面保護層が設けられてなる。
【００３８】
本発明の構成は、導電性支持体上に少なくとも、感光層、表面保護層を少なくとも有していれば、上記のその他の層等、任意に組み合わされていても構わない。
導電性支持体としては、体積抵抗１０^１０ Ω・ｃｍ以下の導電性を示すもの、例えば、アルミニウム、ニッケル、クロム、ニクロム、銅、金、銀、白金などの金属、酸化スズ、酸化インジウムなどの金属酸化物を、蒸着またはスパッタリングにより、フィルム状もしくは円筒状のプラスチック、紙に被覆したもの、あるいは、アルミニウム、アルミニウム合金、ニッケル、ステンレスなどの板およびそれらを、押し出し、引き抜きなどの工法で素管化後、切削、超仕上げ、研摩などの表面処理した管などを使用することができる。また、特開昭５２−３６０１６号公報に開示されたエンドレスニッケルベルト、エンドレスステンレスベルトも導電性支持体として用いることができる。
【００３９】
この他、上記支持体上に導電性粉体を適当な結着樹脂に分散して塗工したものも、本発明の導電性支持体として用いることができる。この導電性粉体としては、カーボンブラック、アセチレンブラック、またアルミニウム、ニッケル、鉄、ニクロム、銅、亜鉛、銀などの金属粉、あるいは導電性酸化スズ、ＩＴＯなどの金属酸化物粉体などが挙げられる。また、同時に用いられる結着樹脂には、ポリスチレン、スチレン−アクリロニトリル共重合体、スチレン−ブタジエン共重合体、スチレン−無水マレイン酸共重合体、ポリエステル、ポリ塩化ビニル、塩化ビニル−酢酸ビニル共重合体、ポリ酢酸ビニル、ポリ塩化ビニリデン、ポリアリレート樹脂、フェノキシ樹脂、ポリカーボネート、酢酸セルロース樹脂、エチルセルロース樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルトルエン、ポリ−Ｎ−ビニルカルバゾール、アクリル樹脂、シリコーン樹脂、エポキシ樹脂、メラミン樹脂、ウレタン樹脂、フェノール樹脂、アルキッド樹脂などの熱可塑性、熱硬化性樹脂または光硬化性樹脂が挙げられる。このような導電性層は、これらの導電性粉体と結着樹脂を適当な溶剤、例えば、テトラヒドロフラン、ジクロロメタン、メチルエチルケトン、トルエンなどに分散して塗布することにより設けることができる。
【００４０】
さらに、適当な円筒基体上にポリ塩化ビニル、ポリプロピレン、ポリエステル、ポリスチレン、ポリ塩化ビニリデン、ポリエチレン、塩化ゴム、ポリテトラフロロエチレン系フッ素樹脂などの素材に前記導電性粉体を含有させた熱収縮チューブによって導電性層を設けてなるものも、本発明の導電性支持体として良好に用いることができる。
【００４１】
次に感光層について説明する。感光層は単層でも積層でもよいが、説明の都合上、先ず電荷発生層と電荷輸送層で構成される場合から述べる。
電荷発生層は、電荷発生物質を主成分とする層である。
電荷発生層には、公知の電荷発生物質を用いることが可能であり、その代表として、モノアゾ顔料、ジスアゾ顔料、トリスアゾ顔料、ペリレン系顔料、ペリノン系顔料、キナクリドン系顔料、キノン系縮合多環化合物、スクアリック酸系染料、他のフタロシアニン系顔料、ナフタロシアニン系顔料、アズレニウム塩系染料等が挙げられ用いられる。これら電荷発生物質は、単独でも２種以上混合してもかまわない。
中でもアゾ顔料および／またはフタロシアニン顔料が有効に用いられる。特に下記構造式（１）で表わされるアゾ顔料、およびチタニルフタロシアニン（特にＣｕＫαの特性Ｘ線（波長１．５１４Å）に対するブラッグ角２θの回折ピーク（±０．２゜）として、少なくとも２７．２゜に最大回折ピークを有するチタニルフタロシアニン）が有効に使用できる。
【００４２】
【化２７】

式中、Ｃｐ_１、Ｃｐ_２はカップラー残基を表わし、同一でも異なっていても良い。Ｒ_２０１、Ｒ_２０２はそれぞれ、水素原子、ハロゲン原子、アルキル基、アルコキシ基、シアノ基のいずれかを表わし、同一でも異なっていても良い。またＣｐ_１、Ｃｐ_２は下記（２）式で表わされ、
【００４３】
【化２８】

式中、Ｒ_２０３は、水素原子、メチル基、エチル基などのアルキル基、フェニル基などのアリール基を表わす。Ｒ_２０４、Ｒ_２０５、Ｒ_２０６、Ｒ_２０７、Ｒ_２０８はそれぞれ、水素原子、ニトロ基、シアノ基、フッ素、塩素、臭素、ヨウ素などのハロゲン原子、トリフルオロメチル基、メチル基、エチル基などのアルキル基、メトキシ基、エトキシ基などのアルコキシ基、ジアルキルアミノ基、水酸基を表わし、Ｚは置換もしくは無置換の芳香族炭素環または置換もしくは無置換の芳香族複素環を構成するのに必要な原子群を表わす。
【００４４】
電荷発生層は、必要に応じて結着樹脂とともに適当な溶剤中にボールミル、アトライター、サンドミル、超音波などを用いて分散し、これを導電性支持体上に塗布し、乾燥することにより形成される。
必要に応じて電荷発生層に用いられる結着樹脂としては、ポリアミド、ポリウレタン、エポキシ樹脂、ポリケトン、ポリカーボネート、シリコン樹脂、アクリル樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルケトン、ポリスチレン、ポリスルホン、ポリ−Ｎ−ビニルカルバゾール、ポリアクリルアミド、ポリビニルベンザール、ポリエステル、フェノキシ樹脂、塩化ビニル−酢酸ビニル共重合体、ポリ酢酸ビニル、ポリフェニレンオキシド、ポリアミド、ポリビニルピリジン、セルロース系樹脂、カゼイン、ポリビニルアルコール、ポリビニルピロリドン等が挙げられる。結着樹脂の量は、電荷発生物質１００重量部に対し０〜５００重量部、好ましくは１０〜３００重量部が適当である。
【００４５】
ここで用いられる溶剤としては、イソプロパノール、アセトン、メチルエチルケトン、シクロヘキサノン、テトラヒドロフラン、ジオキサン、エチルセロソルブ、酢酸エチル、酢酸メチル、ジクロロメタン、ジクロロエタン、モノクロロベンゼン、シクロヘキサン、トルエン、キシレン、リグロイン等が挙げられるが、特にケトン系溶媒、エステル系溶媒、エーテル系溶媒が良好に使用される。塗布液の塗工法としては、浸漬塗工法、スプレーコート、ビートコート、ノズルコート、スピナーコート、リングコート等の方法を用いることができる。
電荷発生層の膜厚は、０．０１〜５μｍ程度が適当であり、好ましくは０．１〜２μｍである。
【００４６】
電荷輸送層は、電荷輸送物質および結着樹脂を適当な溶剤に溶解ないし分散し、これを電荷発生層上に塗布、乾燥することにより形成できる。また、必要により可塑剤、レベリング剤、酸化防止剤等を添加することもできる。
電荷輸送物質には、正孔輸送物質と電荷輸送物質とがある。電荷輸送物質としては、例えばクロルアニル、ブロムアニル、テトラシアノエチレン、テトラシアノキノジメタン、２，４，７−トリニトロ−９−フルオレノン、２，４，５，７−テトラニトロ−９−フルオレノン、２，４，５，７−テトラニトロキサントン、２，４，８−トリニトロチオキサントン、２，６，８−トリニトロ−４Ｈ−インデノ〔１，２−ｂ〕チオフェン−４−オン、１，３，７−トリニトロジベンゾチオフェン−５，５−ジオキサイド、ベンゾキノン誘導体等の電子受容性物質が挙げられる。
【００４７】
正孔輸送物質としては、ポリ−Ｎ−ビニルカルバゾールおよびその誘導体、ポリ−γ−カルバゾリルエチルグルタメートおよびその誘導体、ピレン−ホルムアルデヒド縮合物およびその誘導体、ポリビニルピレン、ポリビニルフェナントレン、ポリシラン、オキサゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、モノアリールアミン誘導体、ジアリールアミン誘導体、トリアリールアミン誘導体、スチルベン誘導体、α−フェニルスチルベン誘導体、ベンジジン誘導体、ジアリールメタン誘導体、トリアリールメタン誘導体、９−スチリルアントラセン誘導体、ピラゾリン誘導体、ジビニルベンゼン誘導体、ヒドラゾン誘導体、インデン誘導体、ブタジェン誘導体、ピレン誘導体等、ビススチルベン誘導体、エナミン誘導体等その他公知の材料が挙げられる。これらの電荷輸送物質は単独、または２種以上混合して用いられる。
また、電荷輸送物質としての機能とバインダー樹脂の機能を持った高分子電荷輸送物質も良好に使用される。高分子電荷輸送物質としては、公知の材料が使用できる。
【００４８】
結着樹脂としては、ポリスチレン、スチレン−アクリロニトリル共重合体、スチレン−ブタジエン共重合体、スチレン−無水マレイン酸共重合体、ポリエステル、ポリ塩化ビニル、塩化ビニル−酢酸ビニル共重合体、ポリ酢酸ビニル、ポリ塩化ビニリデン、ポリアレート、フェノキシ樹脂、ポリカーボネート、酢酸セルロース樹脂、エチルセルロース樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルトルエン、ポリ−Ｎ−ビニルカルバゾール、アクリル樹脂、シリコーン樹脂、エポキシ樹脂、メラミン樹脂、ウレタン樹脂、フェノール樹脂、アルキッド樹脂等の熱可塑性または熱硬化性樹脂が挙げられる。
【００４９】
電荷輸送物質の量は結着樹脂１００重量部に対し、２０〜３００重量部、好ましくは４０〜１５０重量部が適当である。また、電荷輸送層の膜厚は解像度・応答性の点から、２５μｍ以下とすることが好ましい。下限値に関しては、使用するシステム（特に帯電電位等）により異なるが、５μｍ以上が好ましい。
【００５０】
ここで用いられる溶剤としては、テトラヒドロフラン、ジオキサン、トルエン、ジクロロメタン、モノクロロベンゼン、ジクロロエタン、シクロヘキサノン、メチルエチルケトン、アセトンなどが用いられる。
【００５１】
本発明の感光体においては電荷輸送層中に可塑剤やレベリング剤を添加してもよい。可塑剤としては、ジブチルフタレート、ジオクチルフタレートなど一般の樹脂の可塑剤として使用されているものがそのまま使用でき、その使用量は、結着樹脂に対して０〜３０重量％程度が適当である。レベリング剤としては、ジメチルシリコーンオイル、メチルフェニルシリコーンオイルなどのシリコーンオイル類や、側鎖にパーフルオロアルキル基を有するポリマーあるいはオリゴマーが使用され、その使用量は結着樹脂に対して、０〜１重量％が適当である。
【００５２】
次に、感光層が単層構成の場合について述べる。上述した電荷発生物質を結着樹脂中に分散した感光体が使用できる。単層感光層は、電荷発生物質および電荷輸送物質および結着樹脂を適当な溶剤に溶解ないし分散し、これを塗布、乾燥することによって形成できる。さらに、この感光層には上述した電荷輸送材料を添加した機能分離タイプとしても良く、良好に使用できる。また、必要により、可塑剤やレベリング剤、酸化防止剤等を添加することもできる。
【００５３】
結着樹脂としては、先に電荷輸送層で挙げた結着樹脂をそのまま用いるほかに、電荷発生層で挙げた結着樹脂を混合して用いてもよい。もちろん、先に挙げた高分子電荷輸送物質も良好に使用できる。結着樹脂１００重量部に対する電荷発生物質の量は５〜４０重量部が好ましく、電荷輸送物質の量は０〜１９０重量部が好ましく、さらに好ましくは５０〜１５０重量部である。単層感光層は、電荷発生物質、結着樹脂を必要ならば電荷輸送物質とともにテトラヒドロフラン、ジオキサン、ジクロロエタン、シクロヘキサン等の溶媒を用いて分散機等で分散した塗工液を、浸漬塗工法やスプレーコート、ビードコートなどで塗工して形成できる。単層感光層の膜厚は、５〜２５μｍ程度が適当である。
【００５４】
本発明の感光体においては、導電性支持体と感光層との間に下引き層を設けることができる。下引き層は一般には樹脂を主成分とするが、これらの樹脂はその上に感光層を溶剤で塗布することを考えると、一般の有機溶剤に対して耐溶剤性の高い樹脂であることが望ましい。このような樹脂としては、ポリビニルアルコール、カゼイン、ポリアクリル酸ナトリウム等の水溶性樹脂、共重合ナイロン、メトキシメチル化ナイロン等のアルコール可溶性樹脂、ポリウレタン、メラミン樹脂、フェノール樹脂、アルキッド−メラミン樹脂、エポキシ樹脂等、三次元網目構造を形成する硬化型樹脂等が挙げられる。また、下引き層にはモアレ防止、残留電位の低減等のために酸化チタン、シリカ、アルミナ、酸化ジルコニウム、酸化スズ、酸化インジウム等で例示できる金属酸化物の微粉末顔料を加えてもよい。
【００５５】
これらの下引き層は前述の感光層の如く適当な溶媒、塗工法を用いて形成することができる。更に本発明の下引き層として、シランカップリング剤、チタンカップリング剤、クロムカップリング剤等を使用することもできる。この他、本発明の下引き層には、Ａｌ_２Ｏ_３を陽極酸化にて設けたものや、ポリパラキシリレン（パリレン）等の有機物やＳｉＯ_２、ＳｎＯ_２、ＴｉＯ_２、ＩＴＯ、ＣｅＯ_２等の無機物を真空薄膜作成法にて設けたものも良好に使用できる。このほかにも公知のものを用いることができる。下引き層の膜厚は０〜５μｍが適当である。
【００５６】
本発明の感光体においては、感光層保護の目的で、表面保護層が感光層の上に設けられる。
表面保護層に使用されるバインダー樹脂としては、少なくともイソシアネートとポリオールを架橋重合したウレタン樹脂とトリフェニルアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体が用いられる。
イソシアネート材料は一般的なイソシアネート材料を用いることが可能である。しかし、感光体の表面保護層として用いるためには、経時により膜が変色しない、無黄変タイプのイソシアネート材料が好ましい。さらに、機械的耐久性が良好なイソシアネート材料としては、３官能以上のイソシアネート材料が好ましい。これらのイソシアネート材料を下記に例示する。
【００５７】
【化２９】

例示化合物１（ＨＤＩアダクト）
【００５８】
【化３０】

例示化合物２（ＩＰＤＩアダクト）
【００５９】
【化３１】

例示化合物３（ＨＤＩトリマー）
これらのイソシアネート材料は単独もしくは混合して使用することができる。
【００６０】
次に、ポリオール材料は、ポリエーテルポリオール、ポリエステルポリオール、アクリルポリオール、エポキシポリオール、ポリカーボネート骨格を有するポリカーボネートジオールなどが用いられる。機械的耐久性の良好なポリオール材料としては、下記構造のポリオール材料が好ましい。
【００６１】
【化３２】

（式中、Ｒは、水素原子、炭素数１〜５のアルキル基を表わし、ｎ＝１〜５である。）
さらに良好なポリオール材料としては、上記構造のポリオールの分子量が、１００以上１５０以下であることが好ましい。
下記にこれらのポリオールの例を示す。
【００６２】
【化３３】

例示化合物４（分子量３３４．１６）
【００６３】
【化３４】

例示化合物５（分子量１７６．２５）
【００６４】
【化３５】

例示化合物６（分子量１３４．１７）
【００６５】
【化３６】

例示化合物７（分子量１０６．１２）
【００６６】
【化３７】

例示化合物８（分子量１２０．０９）
【００６７】
イソシアネートのＮＣＯ基数とポリオールのＯＨ基数の比（ＮＣＯ／ＯＨ比）は、１．０〜１．５程度が望ましい。
【００６８】
保護層にはウレタン樹脂とトリアリールアミン構造を主鎖および／または側鎖に含むポリカーボネート重合体が用いられる。これらのトリアリールアミン構造を主鎖および／または側鎖に含むポリカーボネート重合体を、下記一般式（１）〜一般式（１０）で、例示する。
【００６９】
【化３８】

式中、Ｒ_１，Ｒ_２，Ｒ_３はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ_４は水素原子又は置換もしくは無置換のアルキル基、Ｒ_５，Ｒ_６は置換もしくは無置換のアリール基、ｏ，ｐ，ｑはそれぞれ独立して０〜４の整数、ｋ，ｊは組成を表わし、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表わし、５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表わされる２価基を表わす。
【００７０】
【化３９】

式中、Ｒ_１０１，Ｒ_１０２は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表わす。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−，−Ｓ−，−ＳＯ−，−ＳＯ_２−，−ＣＯ−，−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表わす。）または、
【００７１】
【化４０】

（式中、ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換または無置換のアルキル基又はアリール基を表わす。）を表わす。ここで、Ｒ_１０１とＲ_１０２，Ｒ_１０３とＲ_１０４は、それぞれ同一でも異なってもよい。
【００７２】
【化４１】

式中、Ｒ_７，Ｒ_８は置換もしくは無置換のアリール基、Ａｒ_１，Ａｒ_２，Ａｒ_３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７３】
【化４２】

式中、Ｒ_９，Ｒ_１０は置換もしくは無置換のアリール基、Ａｒ_４，Ａｒ_５，Ａｒ_６は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（一般式１の場合と同じである。
【００７４】
【化４３】

式中、Ｒ_１１，Ｒ_１２は置換もしくは無置換のアリール基、Ａｒ_７，Ａｒ_８，Ａｒ_９は同一又は異なるアリレン基、ｐは１〜５の整数を表わす。 Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７５】
【化４４】

式中、Ｒ_１３，Ｒ_１４は置換もしくは無置換のアリール基、Ａｒ_１０，Ａｒ_１１，Ａｒ_１２は同一又は異なるアリレン基、Ｘ_１，Ｘ_２は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７６】
【化４５】

式中、Ｒ_１５，Ｒ_１６，Ｒ_１７，Ｒ_１８は置換もしくは無置換のアリール基、Ａｒ_１３，Ａｒ_１４，Ａｒ_１５，Ａｒ_１６は同一又は異なるアリレン基、Ｙ_１，Ｙ_２，Ｙ_３は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わし、同一であっても異なってもよい。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７７】
【化４６】

式中、Ｒ_１９，Ｒ_２０は水素原子、置換もしくは無置換のアリール基を表わし、Ｒ_１９とＲ_２０は環を形成していてもよい。Ａｒ_１７，Ａｒ_１８，Ａｒ_１９は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７８】
【化４７】

式中、Ｒ_２１は置換もしくは無置換のアリール基、Ａｒ_２０，Ａｒ_２１，Ａｒ_２２，Ａｒ_２３は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００７９】
【化４８】

式中、Ｒ_２２，Ｒ_２３，Ｒ_２４，Ｒ_２５は置換もしくは無置換のアリール基、Ａｒ_２４，Ａｒ_２５，Ａｒ_２６，Ａｒ_２７，Ａｒ_２８は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
【００８０】
【化４９】

式中、Ｒ_２６，Ｒ_２７は置換もしくは無置換のアリール基、Ａｒ_２９，Ａｒ_３０，Ａｒ_３１は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、一般式１の場合と同じである。
これらの高分子電荷輸送材料は、単独もしくは混合して使用することができる。
ウレタン樹脂と高分子電荷輸送材料の混合比（重量）は、１／３〜２／１程度であり、好ましくは２／３〜３／２程度である。
【００８１】
表面保護層の厚さは０．１〜１０μｍ程度が適当であり、好ましくは、１．０〜８．０μｍの範囲である。長期的に繰り返し使用される感光体は、機械的に耐久性が高く、摩耗しにくいものとする。しかし実機内では、帯電部材などから、オゾン及びＮＯｘガスなどが発生し、感光体の表面に付着する。こららの付着物が存在すると、画像流れが発生する。この画像流れを防止するためには、感光層をある一定速度以上に摩耗する必要がある。そのためには、長期的な繰り返し使用を考慮した場合、表面保護層は少なくとも１．０μｍ以上の膜厚であることが好ましい。また、膜厚が８．０μｍ以上では、残留電位上昇や微細ドット再現性の低下が考えられる。
【００８２】
ここで用いられる溶剤としては、イソプロパノール、アセトン、メチルエチルケトン、シクロヘキサノン、テトラヒドロフラン、ジオキサン、エチルセロソルブ、セロソルブアセテート、酢酸エチル、酢酸メチル、ジクロロメタン、ジクロロエタン、モノクロロベンゼン、シクロヘキサン、トルエン、キシレン、リグロイン等が挙げられる。
【００８３】
塗工法としては、浸漬塗工法、スプレーコート、ビートコート、ノズルコート、スピナーコート、リングコート等の方法を用いることができる。製膜される膜の均一性、塗工時の下層への浸食性等を考慮した場合、微小開口部を有するノズルより塗工液を吐出し、霧化することにより生成した微小液滴を感光層上に付着させて塗膜を形成するスプレー塗工方法が好ましい。
【００８４】
次に、図面を用いて本発明の電子写真方法ならびに電子写真装置を詳しく説明する。
図４は、本発明の電子写真プロセスおよび電子写真装置を説明するための概略図であり、下記するような変形例も本発明の範疇に属するものである。
図４において、感光体（１）は導電性支持体上に、少なくとも感光層と請求項１乃至１１に記載の表面保護層が設けられてなる。感光体（１）はドラム状の形状を示しているが、シート状、エンドレスベルト状のものであっても良い。帯電ローラー（８）、転写前チャージャ（１２）、転写チャージャ（１５ａ）、分離チャージャ（１５ｂ）、クリーニング前チャージャ（１７）には、コロトロン、スコロトロン、固体帯電器（ソリッド・ステート・チャージャー）、帯電ローラを始めとする公知の手段が用いられる。帯電部材は、感光体に対し接触もしくは近接配置したものが良好に用いられる。また、帯電用部材により感光体に帯電を施す際、帯電部材に直流成分に交流成分を重畳した電界により感光体に帯電を与えることにより、帯電ムラを低減することが可能で効果的である。
転写手段には、一般に上記の帯電器が使用できるが、図に示されるように転写チャージャーと分離チャージャーを併用したものが効果的である。
【００８５】
また、画像露光部（１０）、除電ランプ（７）等の光源には、蛍光灯、タングステンランプ、ハロゲンランプ、水銀灯、ナトリウム灯、発光ダイオード（ＬＥＤ）、半導体レーザー（ＬＤ）、エレクトロルミネッセンス（ＥＬ）などの発光物全般を用いることができる。好ましく発光ダイオード、半導体レーザーが用いられる。そして、所望の波長域の光のみを照射するために、シャープカットフィルター、バンドパスフィルター、近赤外カットフィルター、ダイクロイックフィルター、干渉フィルター、色温度変換フィルターなどの各種フィルターを用いることもできる。
かかる光源等は、図４に示される工程の他に光照射を併用した転写工程、除電工程、クリーニング工程、あるいは前露光などの工程を設けることにより、感光体に光が照射される。
【００８６】
さて、現像ユニット（１１）により感光体（１）上に現像されたトナーは、転写紙（１４）に転写されるが、全部が転写されるわけではなく、感光体（１）上に残存するトナーも生ずる。このようなトナーは、ファーブラシ（１８）およびブレード（１９）により、感光体より除去される。クリーニングは、クリーニングブラシだけで行なわれることもあり、クリーニングブラシにはファーブラシ、マグファーブラシを始めとする公知のものが用いられる。
【００８７】
電子写真感光体に正（負）帯電を施し、画像露光を行なうと、感光体表面上には正（負）の静電潜像が形成される。
これを負（正）極性のトナー（検電微粒子）で現像すれば、ポジ画像が得られるし、また正（負）極性のトナーで現像すれば、ネガ画像が得られる。
かかる現像手段には、公知の方法が適用されるし、また、除電手段にも公知の方法が用いられる。
【００８８】
図５には、本発明による電子写真プロセスの別の例を示す。感光体（２１）は導電性支持体上に、少なくとも感光層と請求項１乃至８記載の表面保護層が設けられてなる。駆動ローラ（２２ａ），（２２ｂ）により駆動され、帯電器（２３）による帯電、光源（２４）による像露光、現像（図示せず）、帯電器（２５）を用いる転写、光源（２６）によるクリーニング前露光、ブラシ（２７）によるクリーニング、光源（２８）による除電が繰り返し行なわれる。図５においては、感光体（２１）（勿論この場合は支持体が透光性である）に支持体側よりクリーニング前露光の光照射が行なわれる。
【００８９】
以上の図示した電子写真プロセスは、本発明における実施形態を例示するものであって、もちろん他の実施形態も可能である。例えば、図５において支持体側よりクリーニング前露光を行なっているが、これは感光層側から行なってもよいし、また、像露光、除電光の照射を支持体側から行なってもよい。
一方、光照射工程は、像露光、クリーニング前露光、除電露光が図示されているが、他に転写前露光、像露光のプレ露光、およびその他公知の光照射工程を設けて、感光体に光照射を行なうこともできる。
【００９０】
以上に示すような画像形成手段は、複写装置、ファクシミリ、プリンター内に固定して組み込まれていてもよいが、プロセスカートリッジの形でそれら装置内に組み込まれてもよい。プロセスカートリッジとは、感光体を内蔵し、他に帯電手段、露光手段、現像手段、転写手段、クリーニング手段、除電手段を含んだ１つの装置（部品）である。プロセスカートリッジの形状等は多く挙げられるが、一般的な例として、図６に示すものが挙げられる。感光体（３０）は、導電性支持体上に、少なくとも感光層と表面保護層が設けられてなる。
【００９１】
【実施例】
以下、本発明を実施例及び比較例により説明するが、これにより本発明の態様が限定されるものではない。
実施例１
Ａｌ製支持体（外径３０ｍｍφ）に、乾燥後の膜厚が３．５μｍになるように浸漬法で塗工し、下引き層を形成した。
・下引き層用塗工液
アルキッド樹脂
（ベッコゾール１３０７−６０−ＥＬ：大日本インキ化学工業）
メラミン樹脂
（スーパーベッカミンＧ−８２１−６０：大日本インキ化学工業）
酸化チタン（ＣＲ−ＥＬ：石原産業）
メチルエチルケトン
＜混合比（重量）＞
アルキッド樹脂／メラミン樹脂／酸化チタン／メチルエチルケトン＝３／２／２０／１００
【００９２】
この下引き層上に下記構造のビスアゾ顔料を含む電荷発生層塗工液に浸漬塗工し、加熱乾燥させ、膜厚０．２μｍの電荷発生層を形成した。
・電荷発生層用塗工液
下記構造のビスアゾ顔料
【００９３】
【化５０】

ポリビニルブチラール（ＸＹＨＬ：ＵＣＣ）
２−ブタノン
シクロヘキサノン
＜混合比（重量）＞
ビスアゾ顔料／ポリビニルブチラール／２−ブタノン／シクロヘキサノン＝５／１／１００／２００
【００９４】
この電荷発生層上に下記構造の低分子電荷輸送物質を含む電荷輸送層用塗工液を用いて、浸積塗工し、加熱乾燥させ、膜厚２２μｍの電荷輸送層とした。
・電荷輸送層用塗工液
ビスフェーノルＺ型ポリカーボネート
下記構造の低分子電荷輸送物質
【００９５】
【化５１】

テトラヒドロフラン
＜混合比（重量）＞
ポリカーボネート／電荷輸送物質／テトラヒドロフラン＝１／１／１０
【００９６】
この電荷輸送層上に下記塗工液を用いてスプレー塗工し、１５０℃加熱乾燥させ、膜厚５．０μｍの表面保護層とした。
・表面保護層用塗工液
イソシアネート（タケネートＤ１４０Ｎ（ＩＰＤＩアダクト）：三井武田ケミカル社製）
ポリオール（ＬＺＲ１７０（スチレン−アクリル共重合体）：藤倉化成社製）
【００９７】
【化５２】

下記構造の高分子電荷輸送材料
【００９８】
【化５３】

アセトン
セロソルブアセテート
メチルイソブチルケトン
＜混合条件＞
ＮＣＯ／ＯＨ＝１．０
固形分濃度：１０ｗｔ％
ウレタン樹脂／高分子電荷輸送材料混合比（重量）＝１／１
溶剤混合比（重量）：アセトン／セロソルブアセテート／メチルイソブチルケトン＝４／４／１
【００９９】
実施例２
表面保護層塗工液中のポリオールを下記構造のポリオールにすること以外は全て実施例１と同じにして感光体を作製した。
ポリオール（下記構造のポリオール：分子量３３４．１６）
【０１００】
【化５４】

【０１０１】
実施例３
表面保護層塗工液中のポリオールを下記構造のポリオールにすること以外は全て実施例１と同じにして感光体を作製した。
ポリオール（下記構造のポリオール：分子量１７６．２５）
【０１０２】
【化５５】

【０１０３】
実施例４
表面保護層塗工液中のポリオールを下記構造のポリオールにすること以外は全て実施例１と同じにして感光体を作製した。
ポリオール（下記構造のポリオール：分子量１３４．１７）
【０１０４】
【化５６】

【０１０５】
実施例５
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１０６】
【化５７】

【０１０７】
実施例６
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１０８】
【化５８】

【０１０９】
実施例７
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１１０】
【化５９】

【０１１１】
実施例８
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１１２】
【化６０】

【０１１３】
実施例９
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１１４】
【化６１】

【０１１５】
実施例１０
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１１６】
【化６２】

【０１１７】
実施例１１
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１１８】
【化６３】

【０１１９】
実施例１２
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１２０】
【化６４】

【０１２１】
実施例１３
表面保護層塗工液中の高分子電荷輸送材料を下記構造の高分子電荷輸送材料にすること以外は全て実施例４と同じにして感光体を作製した。
【０１２２】
【化６５】

【０１２３】
実施例１４
表面保護層膜厚を７．０μｍとすること以外は全て実施例４と同じにして感光体を作製した。
【０１２４】
実施例１５
表面保護層膜厚を９．０μｍとすること以外は全て実施例４と同じにして感光体を作製した。
【０１２５】
比較例１
表面保護層を設けないこと以外は全て実施例１と同じにして感光体を作製した。
【０１２６】
比較例２
表面保護層塗工液中に高分子電荷輸送材料を入れないこと以外は全て実施例１と同じにして感光体を作製した。
【０１２７】
比較例３
表面保護層塗工液中にイソシアネート及びポリオールを含有させないこと以外は全て実施例１と同じにして感光体を作製した。
【０１２８】
比較例４
表面保護層塗工液中に、高分子電荷輸送材料の代わりに下記構造の低分子電荷輸送材料を含有させること以外は全て実施例１と同じにして感光体を作製した。
【０１２９】
【化６６】

【０１３０】
得られた感光体を、Ｉｐｓｉｏ Ｃｏｌｏｒ ７１００（ＡＣ／ＤＣ帯電、近接配置帯電ローラー）を用いて、モノクロ連続コピー１０万枚（Ａ４）通紙試験を行なった。そして、初期及びラン後の画像（ドット再現性）、摩耗量、露光部電位を測定した。結果を表１、２に示す。
【０１３１】
【表１】

【０１３２】
・ドット再現性（平均ビーム径を５０μｍとし、１ドット独立書き込みを行ない、現像後の感光体表面のドット再現性及びトナー飛散状況を光学顕微鏡を用いて評価した。）
○…良好
△…ドット太りがみられる
×…ドット太りにくわえ、トナー飛散もみられる
【０１３３】
【表２】

＊実施例１、２、比較例２、３は、表面保護層が摩耗により消失したため、通紙試験を停止した。
＊比較例１は、膜厚減少が大きかっため、５万枚通紙後の通紙試験を停止した。
【０１３４】
【発明の効果】
以上、詳細かつ具体的な説明より明らかなように、導電性支持体上に少なくとも感光層及び表面保護層を有する電子写真感光体において、該表面保護層が少なくともイソシアネートとポリオールを架橋重合したウレタン樹脂と高分子電荷輸送材料を含有し、該高分子電荷輸送材料がトリフェニルアミン骨格を主鎖または／かつ側鎖に有するポリカーボネートの重合体であることを特徴とする電子写真感光体とすることにより、機械的耐久性、電気特性、画像特性が良好な画像形成方法が提供できる。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の構成例を示す断面図である。
【図２】本発明の電子写真感光体の他の構成例を示す断面図である。
【図３】本発明の電子写真感光体の他の構成例を示す断面図である。
【図４】本発明の電子写真プロセスおよび電子写真装置を説明するための概略図である。
【図５】本発明による電子写真プロセスの別の例である。
【図６】本発明のプロセスカートリッジを示す別の図である。
【符号の説明】
１ 感光体
７ 除電ランプ
８ 帯電ローラ
９ イレーサー
１０ 画像露光部
１１ 現像ユニット
１２ 転写前チャージャ
１３ レジストローラ
１４ 転写紙
１５ 転写体
１５ａ 転写チャージャ
１５ｂ 分離チャージャ
１７ クリーニング前チャージャ
１８ ファーブラシ
１９ ブレード
２１ 感光体
２２ａ 駆動ローラ
２２ｂ 駆動ローラ
２３ 帯電チャージャ
２４ 像露光源
２５ 転写チャージャ
２６ クリーニング前露光
２７ クリーニングブラシ
２８ 除電光源
３０ 感光体
３１ 転写ローラ
３２ 現像ローラ
３３ 画像露光部
３４ 帯電部材
３５ クリーニングブラシ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, a process cartridge, and an image forming method using the same.
Generally, the "electrophotographic method" means that a photoconductive photoreceptor is first charged in a dark place by, for example, corona discharge, and then image-exposed to selectively dissipate the charge of only the exposed portion to obtain an electrostatic latent image. An image forming method in which the latent image portion is developed and visualized with an electric detection fine particle (toner) composed of a colorant such as a dye or a pigment and a binder such as a polymer substance to form an image. One.
[0002]
The basic characteristics required of the photoreceptor in such an electrophotographic method include:
(1) It can be charged to an appropriate potential in a dark place,
(2) little charge dissipation in a dark place;
(3) The charge can be quickly dissipated by light irradiation,
And the like.
[0003]
Conventionally, as a photoreceptor used in an electrophotographic method, a photosensitive layer mainly composed of selenium or a selenium alloy is provided on a conductive support, and an inorganic photoconductive material such as zinc oxide and cadmium sulfide is used in a binder. Are generally known, such as those using an organic photoconductive material such as poly-N-vinylcarbazole and trinitrofluorenone or azo pigment, and those using an amorphous silicone-based material. In recent years, organic electrophotographic photoconductors have been widely used due to low cost, high degree of freedom in photoconductor design, low pollution, and the like.
[0004]
Organic electrophotographic photoreceptors include a photoconductive resin type represented by polyvinyl carbazole (PVK), a charge transfer complex type represented by PVK-TNF (2,4,7-trinitrofluorenone), and a phthalocyanine-binder. And a function-separated type photoreceptor using a combination of a charge generating substance and a charge transporting substance, and a function-separated type photoreceptor is particularly attracting attention.
[0005]
The mechanism of the formation of an electrostatic latent image in this function-separated type photoreceptor is as follows: when light is irradiated after charging the photoreceptor, light passes through a transparent charge transport layer and is absorbed by the charge generating substance in the charge generation layer, The light-absorbing charge-generating substance generates charge carriers, which are injected into the charge-transporting layer, move in the charge-transporting layer according to the electric field generated by the charge, and neutralize the charge on the photoreceptor surface. Thus, an electrostatic latent image is formed. In a function-separated type photoreceptor, it is known to use a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region, and the above-mentioned basic characteristics are sufficiently used. We have something to satisfy.
[0006]
In recent years, as the speed and size of electrophotographic processes have been increasing, there has been a strong demand for photoreceptors to have high reliability and high durability in addition to the above-mentioned characteristics, in order to maintain high image quality even when used repeatedly for a long time. ing.
Photoconductors are subjected to various mechanical and chemical loads in the electrophotographic process. Due to such a load, the photoreceptor is worn, and an abnormal image due to a decrease in film thickness occurs.
[0007]
As a means for increasing the durability of the photoreceptor, there is a method of imparting lubricity to the surface of the protective layer. For example, a proposal has been described in which the surface properties are improved by including a fluorine-modified silicone oil in the surface layer to improve the abrasion resistance of the photoreceptor surface (for example, see Patent Documents 1 to 3). However, such a method of adding the oil component to the photosensitive layer to lower the coefficient of friction does not maintain the abrasion resistance effect because the component transferred to the surface is immediately removed.
[0008]
Further, as another means for increasing durability, a technique of adding a filler to a photoreceptor and a technique of providing a surface protective layer in which a filler is dispersed on the surface of a photosensitive layer have been proposed (for example, see Patent Documents 4 to 8). . The wear resistance of the surface protective layer containing these fillers is improved. However, it was found that due to the influence of the filler dispersion state (uniformity, cohesion, etc.) in the surface protective layer, when fine dot writing was performed, the toner scattered around the dots, resulting in an abnormal image.
[0009]
As another means for increasing the durability, there is a means using a crosslinked resin in the surface layer of the photoreceptor. For example, those using an acrylic cross-linking resin (for example, see Patent Documents 9 and 10), those using a polysiloxane cross-linking resin (for example, see Patent Document 11), and those using a urethane cross-linking resin (for example, , Patent Documents 12 to 14).
When these crosslinked resins are used for the surface layer, the basic skeleton of the crosslinked resin alone does not have a charge transport function, so that the sensitivity is low and the exposed portion potential in the actual machine becomes large. For this purpose, there is a method of imparting a charge transport function to these crosslinked resin surface layers.
[0010]
Further, a material in which a charge transport material is dispersed in a crosslinked resin has been proposed (for example, see Patent Documents 15 and 16). In addition, there is an acrylic or methacrylic acid ester polymer having a charge transport monomer having a specific structure as a repeating unit dispersed in a crosslinked resin (for example, see Patent Document 17). These photoconductors have poor compatibility in the crosslinked resin, and the surface layer is easily clouded. In addition, the low molecular charge transporting substance and the specific structure are dispersed in the crosslinked resin, and when used for a long time, the inherent wear resistance of the crosslinked resin is not exhibited. It became clear that it was easy to wear.
[0011]
Further, in the above-mentioned Patent Documents 11 and 14, there are proposed those in which a skeleton having a charge transport function is cross-linked and polymerized in a cross-linked resin. The surface layer formed by cross-linking and polymerizing the skeleton having the charge transporting function had good electrical characteristics and good mechanical durability. However, when the film was thickened, problems such as cracks occurred due to volume shrinkage of the film generated during the crosslinking polymerization.
[0012]
Further, an electrophotographic photoreceptor characterized in that the photosensitive layer contains a polymer charge transport material containing a polycarbonate having a triarylamine structure in a branched chain has been proposed (for example, see Patent Document 18). There was no description about a surface protective layer using a unique polyol-based polyurethane resin.
[0013]
[Patent Document 1]
JP-A-07-295248 (claims on page 2, column 1, line 1 to line 18)
[Patent Document 2]
JP-A-07-301936 (Claims on page 2, column 1, line 1 to line 15)
[Patent Document 3]
JP-A-08-082940 (Claims on page 2, column 1, line 1 to line 25)
[Patent Document 4]
JP-A-1-205171 (Claims in the fourth line to the eighth line in the lower left column of page 1)
[Patent Document 5]
JP-A-7-333881 (Claim 1 on page 2, column 1, line 2 to line 5, claim 2 on page 2, column 1, line 16 to line 23)
[Patent Document 6]
JP-A-8-15887 (Claims on page 2, column 1, line 1 to line 49)
[Patent Document 7]
Japanese Patent Application Laid-Open No. 8-123005 (Claims on page 2, column 1, line 1 to line 30)
[Patent Document 8]
Japanese Patent Application Laid-Open No. 8-146641 (claims on page 2, column 1, line 1 to line 20)
[Patent Document 9]
Japanese Patent No. 2578548 (Claims 1 to 3 on page 1, column 1, line 1 to page 2, column 3, line 15)
[Patent Document 10]
JP-A-7-261441 (Claim 1 on page 2, column 1, line 2 to line 8)
[Patent Document 11]
JP 2000-241998 (Claims 1 to 8 on page 2, column 1, line 2 to line 35)
[Patent Document 12]
JP-A-5-341550 (Claims on page 2, column 1, line 1 to line 21)
[Patent Document 13]
JP-A-10-177268 (Claims 1 to 9 on page 2, column 1, line 2 to column 2, line 46)
[Patent Document 14]
JP-A-11-38665 (Claims 1 to 7 on page 2, column 1, line 2 to page 3, column 3, line 13)
[Patent Document 15]
JP-A-56-48637 (Claims in the fourth line to the ninth line in the lower left column of page 1)
[Patent Document 16]
JP-A-4-15659 (Claims in the fourth line to the eighth line in the lower left column of page 1)
[Patent Document 17]
JP-A-5-66598 (Claims on page 2, column 1, line 1 to page 3, column 3, line 41)
[Patent Document 18]
JP-A-9-319122 (Claims on page 2, column 1, line 1 to page 12, column 12, line 40)
[0014]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor, an image forming apparatus, a process cartridge and an image forming method using the same, which are excellent in wear resistance, scratch resistance and image stability in long-term use.
[0015]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, completed the present invention.
That is, the object of the present invention is to provide (1) an electrophotographic photoreceptor having at least a photosensitive layer and a surface protective layer on a conductive support, wherein the surface protective layer comprises at least an urethane resin obtained by crosslinking and polymerizing an isocyanate and a polyol. An electrophotographic photoreceptor comprising a polymer charge transport material, wherein the polymer charge transport material is a polycarbonate polymer having a triphenylamine skeleton in a main chain and / or a side chain ”, (2) "The electrophotographic photoreceptor according to the above item (1), wherein the functional group of the isocyanate is trifunctional or more", (3) "the polyol is a polyol having the following structure: The electrophotographic photoreceptor according to the above (1) or (2);
[0016]
Embedded image

(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and n = 1 to 5.) ", (4)" the polyol has a molecular weight of 100 or more and 150 or less. And (5) that the polymer charge transporting substance contains a polycarbonate having a triarylamine structure represented by the following general formula 1 in a branched chain. The electrophotographic photoreceptor according to any one of the above items (1) to (4);
[0017]
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Where R ₁ , R ₂ , R ₃ Are each independently a substituted or unsubstituted alkyl group or halogen atom, R ₄ Is a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ , R ₆ Is a substituted or unsubstituted aryl group, o, p, and q are each independently an integer of 0 to 4, k and j each represent a composition, and 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n Represents the number of repeating units, and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.
[0018]
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Where R ₁₀₁ , R ₁₀₂ Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers from 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -SO ₂ -, -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or
[0019]
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(Where a is an integer of 1 to 20, b is an integer of 1 to 2000, R ₁₀₃ , R ₁₀₄ Represents a substituted or unsubstituted alkyl group or aryl group. ). Where R ₁₀₁ And R ₁₀₂ , R ₁₀₃ And R ₁₀₄ May be the same or different. (6) “(1) to (5), wherein the polymer charge transporting material contains a polycarbonate having a triarylamine structure represented by the following general formula 2 in a branched chain. The electrophotographic photosensitive member according to any one of the above,
[0020]
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Where R ₇ , R ₈ Is a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ , Ar ₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. (7) The above items (1) to (6), wherein the polymer charge transporting material contains a polycarbonate having a triarylamine structure represented by the following general formula 3 in a branched chain. The electrophotographic photoreceptor according to any one of the above,
[0021]
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Where R ₉ , R ₁₀ Is a substituted or unsubstituted aryl group, Ar ₄ , Ar ₅ , Ar ₆ Represents the same or different arylene groups. X, k, j and n are the same as those in the general formula 1. "(8) As the polymer charge transporting material, a polycarbonate having a triarylamine structure represented by the following general formula 4 in a branched chain is used. The electrophotographic photoreceptor according to any one of the above items (1) to (7), which contains:
[0022]
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Where R ₁₁ , R ₁₂ Is a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , Ar ₉ Represents the same or different arylene group, and s represents an integer of 1 to 5. X, k, j and n are the same as in the case of the general formula 1. ", (9)" Polycarbonate having a triarylamine structure represented by the following general formula 5 in the main chain as the polymer charge transporting substance: The electrophotographic photoreceptor according to any one of the above items (1) to (8), which comprises:
[0023]
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Where R _Thirteen , R ₁₄ Is a substituted or unsubstituted aryl group, Ar ₁₀ , Ar ₁₁ , Ar ₁₂ Are the same or different arylene groups, X ₁ , X ₂ Represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j and n are the same as those in the general formula 1), (10) "Polycarbonate having a triarylamine structure represented by the following general formula 6 in a branched chain as the polymer charge transporting substance" The electrophotographic photoreceptor according to any one of the above items (1) to (9), comprising:
[0024]
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Where R _Fifteen , R ₁₆ , R ₁₇ , R ₁₈ Is a substituted or unsubstituted aryl group, Ar _Thirteen , Ar ₁₄ , Ar _Fifteen , Ar ₁₆ Are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ Represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group, and may be the same or different . X, k, j and n are the same as in the case of the general formula 1. ", (11)" Polycarbonate having a triarylamine structure represented by the following general formula 7 in the main chain as the polymer charge transporting substance: The electrophotographic photoreceptor according to any one of the above items (1) to (10), comprising:
[0025]
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Where R ₁₉ , R ₂₀ Represents a hydrogen atom or a substituted or unsubstituted aryl group; ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉ Represents the same or different arylene groups. X, k, j and n are the same as those in the general formula 1. "(12) As the polymer charge transporting substance, a polycarbonate having a triarylamine structure represented by the following general formula 8 in its main chain is used. The electrophotographic photoreceptor according to any one of the above items (1) to (11), comprising:
[0026]
Embedded image

Where R ₂₁ Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , Ar ₂₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. ", (13) As the polymer charge transporting material, a polycarbonate having a triarylamine structure represented by the following general formula 9 in a branched chain is used. The electrophotographic photoreceptor according to any one of the above items (1) to (12);
[0027]
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Where R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ Is a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , Ar ₂₈ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. "(14) As the polymer charge transporting material, a polycarbonate having a main chain having a triarylamine structure represented by the following general formula 10 is used. The electrophotographic photoreceptor according to any one of the above items (1) to (13);
[0028]
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Where R ₂₆ , R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ , Ar ₃₁ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. "(15)" The thickness of the surface protective layer is 1.0 to 8.0 μm. ) To (14).
[0029]
In addition, the above object is achieved by (16) an image forming apparatus including at least a charging unit, an image exposing unit, a developing unit, a transfer unit and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is (1) An image forming apparatus characterized by using the electrophotographic photosensitive member according to any one of the above items (1) to (15) ", (17)" Using the LD or LED of the image exposure means, etc. " (18) The image forming apparatus according to the above (16), wherein an electrostatic latent image is written on the photoconductor by the charging unit. (19) The image forming apparatus according to (16) or (17), wherein the AC component is superimposed on the DC component of the charging member, and It is characterized by giving charge To the second (16) section to be solved by the (18) The image forming apparatus according to any one of Items ".
[0030]
The object of the present invention is also achieved in (20) the present invention relates to a process cartridge in which at least one of a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit and a discharging unit is integrated with an electrophotographic photosensitive member. A process cartridge wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of the above items (1) to (15) ".
[0031]
In addition, the above object is achieved by providing at least (21) the electrophotographic photoreceptor according to any one of the above items (1) to (15). Image forming method characterized by using ".
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
In an electrophotographic photosensitive member having at least a photosensitive layer and a surface protective layer on a conductive support, the surface protective layer contains at least a urethane resin obtained by crosslinking and polymerizing an isocyanate and a polyol, and a polymer charge transport material, An electrophotographic photoreceptor, wherein the transport material is a polycarbonate polymer having a triphenylamine skeleton in a main chain and / or a side chain.
By making the surface protective layer a film having the above structure, the abrasion resistance and electrostatic characteristics of the photoreceptor in long-term use are improved, and the electrophotographic photoreceptor, image forming apparatus, process cartridge, and image having excellent image stability are provided. A forming method can be provided.
[0033]
A urethane resin obtained by crosslinking and polymerizing an isocyanate and a polyol is excellent in mechanical durability. However, since this urethane resin has no charge transport function, it can be used as a protective layer for a thin film of 2 μm or less, but it has not been possible to increase the film thickness in order to maintain durability.
As a method for imparting a charge transporting function to the urethane resin, there is a method of adding a charge transporting substance as mentioned in the prior art. However, in the method of adding these charge transporting substances, the mechanical durability inherent in the urethane resin was reduced.
On the other hand, a polymer charge transporting material, which is a polycarbonate polymer having a triarylamine skeleton in the main chain and / or side chain, has a higher mechanical durability than a film in which a low molecular weight charge transporting material is dispersed in a binder resin. Although the durability is improved, it is not enough for further high durability desired in the future.
[0034]
Therefore, the urethane resin of the present invention has a surface protection layer in which a polymer charge transporting material which is a polymer of a polycarbonate having a triarylamine skeleton in a main chain and / or a side chain is mixed, so that the original urethane resin has It is possible to obtain a surface protective layer having good mechanical durability and improved electrostatic characteristics without lowering the elasticity and toughness of the film.
This is because the resin chain of a polymer charge transport material, which is a polymer of polycarbonate having a triarylamine skeleton having a high mechanical durability and a charge transport function in a main chain or / and a side chain, is entangled with urethane. Since the three-dimensional network of the resin is formed, the surface protection layer having a good charge transport function without a decrease in the mechanical durability inherent in the urethane resin is obtained.
[0035]
Hereinafter, an electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the configuration of the electrophotographic photoreceptor of the present invention. A single-layer photosensitive layer containing a charge generation material and a charge transport material as main components is provided on a conductive support. A surface protective layer is provided on the layer.
[0036]
FIG. 2 is a cross-sectional view showing another configuration example of the electrophotographic photoreceptor of the present invention, in which a charge generation layer mainly composed of a charge generation material and a charge transport material are mainly composed on a conductive support. It has a configuration in which a charge transport layer is laminated, and a surface protective layer is further provided on the charge transport layer.
[0037]
FIG. 3 is a cross-sectional view showing another configuration example of the electrophotographic photoreceptor of the present invention, in which an undercoat layer is provided on a conductive support, and a charge generation material containing a charge generation material as a main component is provided thereon. It has a configuration in which a layer and a charge transport layer containing a charge transport material as a main component are laminated, and further has a surface protective layer provided on the charge transport layer.
[0038]
The configuration of the present invention may be arbitrarily combined with the above-mentioned other layers as long as at least the photosensitive layer and the surface protective layer are provided on the conductive support.
As the conductive support, a volume resistance of 10 ¹⁰ What shows conductivity of Ωcm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver, metals such as platinum, tin oxide, metal oxides such as indium oxide, by evaporation or sputtering, by film Or cylindrical plastic or paper-coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. plates and extruded, drawn out, etc., then tubed, then cut, super-finished, polished, etc. Surface-treated tubes and the like can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support.
[0039]
In addition, those obtained by dispersing a conductive powder on a suitable binder resin on the above-mentioned support and applying the same can also be used as the conductive support of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powder such as conductive tin oxide and ITO. Can be The binder resin used simultaneously includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic, thermosetting resin or photocurable resin such as melamine resin, urethane resin, phenol resin, alkyd resin and the like. Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the dispersion.
[0040]
Further, a heat-shrinkable tube containing the above-mentioned conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chloride rubber, and polytetrafluoroethylene-based fluororesin on a suitable cylindrical substrate. A conductive layer provided with a conductive layer can also be favorably used as the conductive support of the present invention.
[0041]
Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a laminate, but for convenience of explanation, the case where the photosensitive layer is composed of a charge generation layer and a charge transport layer will be described first.
The charge generation layer is a layer containing a charge generation substance as a main component.
For the charge generation layer, known charge generation substances can be used. Representative examples thereof include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinone condensed polycyclic compounds. And squaric acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, azurenium salt dyes, and the like. These charge generating substances may be used alone or in combination of two or more.
Among them, azo pigments and / or phthalocyanine pigments are effectively used. In particular, the azo pigment represented by the following structural formula (1) and titanyl phthalocyanine (particularly, a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to characteristic X-ray (wavelength: 1.514 °) of CuKα) of at least 27.2 ° (A titanyl phthalocyanine having a maximum diffraction peak) can be effectively used.
[0042]
Embedded image

Where Cp ₁ , Cp ₂ Represents a coupler residue, which may be the same or different. R ₂₀₁ , R ₂₀₂ Represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, which may be the same or different. Also Cp ₁ , Cp ₂ Is represented by the following equation (2).
[0043]
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Where R ₂₀₃ Represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ , R ₂₀₈ Are a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine, and iodine; an alkyl group such as a trifluoromethyl group, a methyl group and an ethyl group; an alkoxy group such as a methoxy group and an ethoxy group; Z represents an amino group or a hydroxyl group, and Z represents an atomic group necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring.
[0044]
The charge generation layer is formed by dispersing in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, ultrasonic waves, and the like, coating this on a conductive support, and drying. Is done.
As the binder resin used for the charge generation layer as needed, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N- Vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Can be The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight, per 100 parts by weight of the charge generating substance.
[0045]
Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin, and the like. Ketone solvents, ester solvents, and ether solvents are preferably used. As a method of applying the coating solution, a method such as a dip coating method, a spray coat, a beat coat, a nozzle coat, a spinner coat, and a ring coat can be used.
The thickness of the charge generation layer is suitably about 0.01 to 5 μm, and preferably 0.1 to 2 μm.
[0046]
The charge transporting layer can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying this on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.
The charge transport material includes a hole transport material and a charge transport material. Examples of the charge transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trione Electron accepting substances such as nitrodibenzothiophene-5,5-dioxide, benzoquinone derivatives and the like.
[0047]
Examples of the hole transport material include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethylglutamate and derivatives thereof, pyrene-formaldehyde condensate and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, and oxazole derivatives. Oxadiazole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative, α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9-styrylanthracene derivative, pyrazoline Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. And other known materials. These charge transport materials are used alone or in combination of two or more.
In addition, a polymer charge transporting material having a function as a charge transporting material and a function as a binder resin is also preferably used. Known materials can be used as the polymer charge transport material.
[0048]
As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyalate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol Thermoplastic or thermosetting resins such as resin and alkyd resin.
[0049]
The amount of the charge transporting material is suitably 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. Further, the thickness of the charge transport layer is preferably 25 μm or less from the viewpoint of resolution and response. The lower limit varies depending on the system used (especially the charged potential and the like), but is preferably 5 μm or more.
[0050]
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.
[0051]
In the photoreceptor of the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is suitably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used. % By weight is suitable.
[0052]
Next, a case where the photosensitive layer has a single-layer structure will be described. A photoconductor in which the above-described charge generating substance is dispersed in a binder resin can be used. The single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in a suitable solvent, and applying and drying the resultant. Further, the photosensitive layer may be of a function-separated type to which the above-described charge transport material is added, and can be used favorably. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.
[0053]
As the binder resin, in addition to using the binder resin described above for the charge transport layer as it is, a mixture of the binder resin described for the charge generation layer may be used. Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight, and the amount of the charge transporting substance is preferably 0 to 190 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the binder resin. The single-layer photosensitive layer is formed by dip coating or spraying a coating liquid obtained by dispersing a charge generating substance and a binder resin together with a charge transporting substance, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane using a dispersing machine or the like. It can be formed by coating with a coat or a bead coat. The thickness of the single-layer photosensitive layer is suitably about 5 to 25 μm.
[0054]
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins may be resins having high solvent resistance to general organic solvents. desirable. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, copolymer-soluble nylons, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resins, phenol resins, alkyd-melamine resins, and epoxy resins. Curable resins that form a three-dimensional network structure, such as resins, are exemplified. Further, a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moiré and reduce residual potential.
[0055]
These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-described photosensitive layer. Further, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention includes Al ₂ O ₃ Provided by anodic oxidation, organic substances such as polyparaxylylene (parylene) or SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ Also, inorganic materials such as those provided by a vacuum thin film forming method can be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0056]
In the photoreceptor of the present invention, a surface protective layer is provided on the photosensitive layer for the purpose of protecting the photosensitive layer.
As the binder resin used for the surface protective layer, a urethane resin obtained by crosslinking and polymerizing at least an isocyanate and a polyol, and a polycarbonate polymer having a triphenylamine skeleton in a main chain and / or a side chain are used.
As the isocyanate material, a general isocyanate material can be used. However, for use as a surface protective layer of a photoreceptor, a non-yellowing type isocyanate material which does not discolor the film with the passage of time is preferred. Further, as an isocyanate material having good mechanical durability, a trifunctional or higher functional isocyanate material is preferable. These isocyanate materials are exemplified below.
[0057]
Embedded image

Exemplified compound 1 (HDI adduct)
[0058]
Embedded image

Exemplified compound 2 (IPDI adduct)
[0059]
Embedded image

Exemplified compound 3 (HDI trimer)
These isocyanate materials can be used alone or in combination.
[0060]
Next, as the polyol material, a polyether polyol, a polyester polyol, an acrylic polyol, an epoxy polyol, a polycarbonate diol having a polycarbonate skeleton, or the like is used. As a polyol material having good mechanical durability, a polyol material having the following structure is preferable.
[0061]
Embedded image

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n is 1 to 5.)
As a better polyol material, the polyol having the above structure preferably has a molecular weight of 100 or more and 150 or less.
The following are examples of these polyols.
[0062]
Embedded image

Exemplified compound 4 (molecular weight: 334.16)
[0063]
Embedded image

Exemplified compound 5 (molecular weight: 176.25)
[0064]
Embedded image

Exemplified compound 6 (molecular weight 134.17)
[0065]
Embedded image

Exemplified compound 7 (molecular weight 106.12)
[0066]
Embedded image

Exemplified compound 8 (molecular weight: 120.09)
[0067]
The ratio of the number of NCO groups in the isocyanate to the number of OH groups in the polyol (NCO / OH ratio) is preferably about 1.0 to 1.5.
[0068]
For the protective layer, a polycarbonate polymer containing a urethane resin and a triarylamine structure in a main chain and / or a side chain is used. The following general formulas (1) to (10) exemplify polycarbonate polymers containing these triarylamine structures in the main chain and / or side chain.
[0069]
Embedded image

Where R ₁ , R ₂ , R ₃ Are each independently a substituted or unsubstituted alkyl group or halogen atom, R ₄ Is a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ , R ₆ Is a substituted or unsubstituted aryl group, o, p, and q are each independently an integer of 0 to 4, k and j each represent a composition, and 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n Represents the number of repeating units, and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.
[0070]
Embedded image

Where R ₁₀₁ , R ₁₀₂ Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers from 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -SO ₂ -, -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or
[0071]
Embedded image

(Where a is an integer of 1 to 20, b is an integer of 1 to 2000, R ₁₀₃ , R ₁₀₄ Represents a substituted or unsubstituted alkyl group or aryl group. ). Where R ₁₀₁ And R ₁₀₂ , R ₁₀₃ And R ₁₀₄ May be the same or different.
[0072]
Embedded image

Where R ₇ , R ₈ Is a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ , Ar ₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
[0073]
Embedded image

Where R ₉ , R ₁₀ Is a substituted or unsubstituted aryl group, Ar ₄ , Ar ₅ , Ar ₆ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
[0074]
Embedded image

Where R ₁₁ , R ₁₂ Is a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , Ar ₉ Represents the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as in the case of the general formula 1.
[0075]
Embedded image

Where R _Thirteen , R ₁₄ Is a substituted or unsubstituted aryl group, Ar ₁₀ , Ar ₁₁ , Ar ₁₂ Are the same or different arylene groups, X ₁ , X ₂ Represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j and n are the same as in the case of the general formula 1.
[0076]
Embedded image

Where R _Fifteen , R ₁₆ , R ₁₇ , R ₁₈ Is a substituted or unsubstituted aryl group, Ar _Thirteen , Ar ₁₄ , Ar _Fifteen , Ar ₁₆ Are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ Represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group, and may be the same or different . X, k, j and n are the same as in the case of the general formula 1.
[0077]
Embedded image

Where R ₁₉ , R ₂₀ Represents a hydrogen atom or a substituted or unsubstituted aryl group; ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
[0078]
Embedded image

Where R ₂₁ Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , Ar ₂₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
[0079]
Embedded image

Where R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ Is a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , Ar ₂₈ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
[0080]
Embedded image

Where R ₂₆ , R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ , Ar ₃₁ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1.
These polymer charge transport materials can be used alone or in combination.
The mixing ratio (weight) of the urethane resin and the polymer charge transporting material is about 1/3 to 2/1, preferably about 2/3 to 3/2.
[0081]
The thickness of the surface protective layer is suitably about 0.1 to 10 μm, and preferably in the range of 1.0 to 8.0 μm. A photoreceptor that is used repeatedly for a long period of time has high mechanical durability and is hardly worn. However, in an actual machine, ozone, NOx gas, and the like are generated from a charging member or the like and adhere to the surface of the photoconductor. The presence of these deposits causes image deletion. In order to prevent this image deletion, it is necessary to wear the photosensitive layer at a certain speed or higher. Therefore, in consideration of long-term repeated use, the surface protective layer preferably has a thickness of at least 1.0 μm or more. When the film thickness is 8.0 μm or more, an increase in residual potential and a decrease in reproducibility of fine dots are considered.
[0082]
Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, cellosolve acetate, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. .
[0083]
As a coating method, a method such as a dip coating method, a spray coat, a beat coat, a nozzle coat, a spinner coat, and a ring coat can be used. In consideration of the uniformity of the film to be formed, the erosion of the lower layer during coating, etc., the coating liquid is discharged from the nozzle with the minute opening and the fine droplets generated by atomization are exposed to light. A spray coating method in which a coating film is formed by adhering on a layer is preferred.
[0084]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 4 is a schematic diagram for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modified examples also belong to the category of the present invention.
In FIG. 4, the photoreceptor (1) is provided with at least a photosensitive layer and a surface protective layer according to claims 1 to 11 on a conductive support. The photoconductor (1) has a drum shape, but may have a sheet shape or an endless belt shape. The charging roller (8), the pre-transfer charger (12), the transfer charger (15a), the separation charger (15b), and the pre-cleaning charger (17) include a corotron, a scorotron, a solid state charger (solid state charger), A known means such as a roller is used. As the charging member, one that is in contact with or close to the photoconductor is preferably used. In addition, when charging the photosensitive member by the charging member, the charging member is charged by an electric field in which an AC component is superimposed on a DC component, thereby effectively reducing charging unevenness.
As the transfer means, the above-mentioned charger can be generally used, but as shown in the figure, a combination of a transfer charger and a separation charger is effective.
[0085]
Light sources such as an image exposure unit (10) and a neutralizing lamp (7) include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). ) Can be used. Light emitting diodes and semiconductor lasers are preferably used. To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used.
Such a light source irradiates the photoreceptor with light by providing a transfer step, a charge removal step, a cleaning step, or a pre-exposure step using light irradiation in addition to the step shown in FIG.
[0086]
Now, the toner developed on the photoconductor (1) by the developing unit (11) is transferred to the transfer paper (14), but not all is transferred, and remains on the photoconductor (1). Toner also forms. Such toner is removed from the photoreceptor by the fur brush (18) and the blade (19). Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.
[0087]
When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member.
If this is developed with a negative (positive) polarity toner (electric detection fine particles), a positive image can be obtained, and if it is developed with a positive (negative) polarity toner, a negative image can be obtained.
A known method is applied to the developing unit, and a known method is also used for the charge removing unit.
[0088]
FIG. 5 shows another example of the electrophotographic process according to the present invention. The photoreceptor (21) is provided with at least a photosensitive layer and a surface protective layer according to claims 1 to 8 on a conductive support. Driven by drive rollers (22a) and (22b), charging by charger (23), image exposure by light source (24), development (not shown), transfer using charger (25), and light source (26) Exposure before cleaning, cleaning by the brush (27), and static elimination by the light source (28) are repeatedly performed. In FIG. 5, the photosensitive member (21) (of course, in this case, the support is translucent) is irradiated with light for pre-cleaning exposure from the support side.
[0089]
The illustrated electrophotographic process is an example of an embodiment of the present invention, and other embodiments are of course possible. For example, although the pre-cleaning exposure is performed from the support side in FIG. 5, the exposure may be performed from the photosensitive layer side, or the image exposure and the irradiation of the charge removing light may be performed from the support side.
On the other hand, in the light irradiation step, image exposure, pre-cleaning exposure, and charge removal exposure are shown, but in addition, pre-transfer exposure, pre-exposure of image exposure, and other known light irradiation steps are provided, and the photoconductor is exposed to light. Irradiation can also be performed.
[0090]
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, or may be incorporated in the apparatus in the form of a process cartridge. The process cartridge is one device (part) that includes a photoconductor, and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a discharging unit. There are many shapes and the like of the process cartridge. As a general example, the one shown in FIG. The photoreceptor (30) is provided with at least a photosensitive layer and a surface protective layer on a conductive support.
[0091]
【Example】
Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the embodiments of the present invention are not limited thereto.
Example 1
An undercoat layer was formed on an Al support (outer diameter: 30 mmφ) by an immersion method so that the film thickness after drying was 3.5 μm.
・ Coating liquid for undercoat layer
Alkyd resin
(Beccosol 1307-60-EL: Dainippon Ink and Chemicals, Inc.)
Melamine resin
(Super Beckamine G-821-60: Dainippon Ink and Chemicals, Inc.)
Titanium oxide (CR-EL: Ishihara Sangyo)
Methyl ethyl ketone
<Mixing ratio (weight)>
Alkyd resin / melamine resin / titanium oxide / methyl ethyl ketone = 3/2/20/100
[0092]
On this undercoat layer, a charge generation layer coating solution containing a bisazo pigment having the following structure was applied by dip coating and dried by heating to form a charge generation layer having a thickness of 0.2 μm.
・ Coating solution for charge generation layer
Bisazo pigment of the following structure
[0093]
Embedded image

Polyvinyl butyral (XYHL: UCC)
2-butanone
Cyclohexanone
<Mixing ratio (weight)>
Bisazo pigment / polyvinyl butyral / 2-butanone / cyclohexanone = 5/1/100/200
[0094]
Using a charge transport layer coating solution containing a low molecular charge transport material having the following structure, dip coating was performed on this charge generation layer, followed by heating and drying to form a charge transport layer having a thickness of 22 μm.
・ Coating solution for charge transport layer
Bisphenol Z-type polycarbonate
Low molecular charge transport material with the following structure
[0095]
Embedded image

Tetrahydrofuran
<Mixing ratio (weight)>
Polycarbonate / charge transport material / tetrahydrofuran = 1/1/10
[0096]
The charge transport layer was spray-coated with the following coating solution and dried by heating at 150 ° C. to form a surface protective layer having a thickness of 5.0 μm.
・ Coating liquid for surface protective layer
Isocyanate (Takenate D140N (IPDI adduct): manufactured by Mitsui Takeda Chemical Co., Ltd.)
Polyol (LZR170 (styrene-acrylic copolymer): manufactured by Fujikura Kasei Co., Ltd.)
[0097]
Embedded image

Polymer charge transport material with the following structure
[0098]
Embedded image

acetone
Cellosolve acetate
Methyl isobutyl ketone
<Mixing conditions>
NCO / OH = 1.0
Solid concentration: 10 wt%
Urethane resin / polymer charge transport material mixing ratio (weight) = 1/1
Solvent mixing ratio (weight): acetone / cellosolve acetate / methyl isobutyl ketone = 4/4/1
[0099]
Example 2
A photoconductor was prepared in the same manner as in Example 1 except that the polyol in the coating solution for the surface protective layer was changed to a polyol having the following structure.
Polyol (polyol having the following structure: molecular weight 334.16)
[0100]
Embedded image

[0101]
Example 3
A photoconductor was prepared in the same manner as in Example 1 except that the polyol in the coating solution for the surface protective layer was changed to a polyol having the following structure.
Polyol (polyol having the following structure: molecular weight 176.25)
[0102]
Embedded image

[0103]
Example 4
A photoconductor was prepared in the same manner as in Example 1, except that the polyol in the coating solution for the surface protective layer was changed to a polyol having the following structure.
Polyol (polyol having the following structure: molecular weight 134.17)
[0104]
Embedded image

[0105]
Example 5
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0106]
Embedded image

[0107]
Example 6
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0108]
Embedded image

[0109]
Example 7
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0110]
Embedded image

[0111]
Example 8
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0112]
Embedded image

[0113]
Example 9
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0114]
Embedded image

[0115]
Example 10
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0116]
Embedded image

[0117]
Example 11
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0118]
Embedded image

[0119]
Example 12
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0120]
Embedded image

[0121]
Example 13
A photoconductor was prepared in the same manner as in Example 4, except that the polymer charge transporting material in the coating solution for the surface protective layer was changed to a polymer charge transporting material having the following structure.
[0122]
Embedded image

[0123]
Example 14
A photoconductor was prepared in the same manner as in Example 4, except that the thickness of the surface protective layer was set to 7.0 μm.
[0124]
Example 15
A photoconductor was prepared in the same manner as in Example 4, except that the thickness of the surface protective layer was set to 9.0 μm.
[0125]
Comparative Example 1
A photoconductor was prepared in the same manner as in Example 1 except that no surface protective layer was provided.
[0126]
Comparative Example 2
A photoconductor was prepared in the same manner as in Example 1, except that the polymer charge transporting material was not included in the coating solution for the surface protective layer.
[0127]
Comparative Example 3
A photoconductor was prepared in the same manner as in Example 1, except that the isocyanate and the polyol were not contained in the coating solution for the surface protective layer.
[0128]
Comparative Example 4
A photoconductor was prepared in the same manner as in Example 1, except that the coating solution for the surface protective layer contained a low-molecular charge transport material having the following structure instead of the high-molecular charge transport material.
[0129]
Embedded image

[0130]
The photoreceptor thus obtained was subjected to a 100,000 (A4) monochrome continuous copy paper passing test using Ipsio Color 7100 (AC / DC charging, charging roller arranged in close proximity). Then, the image (dot reproducibility) at the initial stage and after the run, the abrasion amount, and the exposed portion potential were measured. The results are shown in Tables 1 and 2.
[0131]
[Table 1]

[0132]
Dot reproducibility (The average beam diameter was 50 μm, one dot was independently written, and the dot reproducibility on the photoreceptor surface after development and the toner scattering state were evaluated using an optical microscope.)
○… Good
△: dot thickening
×: In addition to dot thickening, toner scattering is also observed
[0133]
[Table 2]

* In Examples 1 and 2 and Comparative Examples 2 and 3, the paper pass test was stopped because the surface protective layer disappeared due to abrasion.
* In Comparative Example 1, the paper passing test after passing 50,000 sheets was stopped because the film thickness was significantly reduced.
[0134]
【The invention's effect】
As apparent from the detailed and specific description above, in an electrophotographic photosensitive member having at least a photosensitive layer and a surface protective layer on a conductive support, the surface protective layer is a urethane resin obtained by crosslinking and polymerizing at least an isocyanate and a polyol. And a polymer charge transport material, wherein the polymer charge transport material is a polycarbonate polymer having a triphenylamine skeleton in a main chain and / or a side chain. And an image forming method having good mechanical durability, electrical characteristics, and image characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration example of an electrophotographic photosensitive member according to the present invention.
FIG. 2 is a cross-sectional view illustrating another configuration example of the electrophotographic photosensitive member of the present invention.
FIG. 3 is a cross-sectional view illustrating another configuration example of the electrophotographic photosensitive member of the present invention.
FIG. 4 is a schematic diagram for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.
FIG. 5 is another example of the electrophotographic process according to the present invention.
FIG. 6 is another view showing the process cartridge of the present invention.
[Explanation of symbols]
1 Photoconductor
7 Static elimination lamp
8 Charging roller
9 Eraser
10 Image exposure section
11 Developing unit
12 Pre-transcription charger
13 Registration roller
14 Transfer paper
15 Transcript
15a Transfer Charger
15b Separate charger
17 Charger before cleaning
18 fur brush
19 blade
21 Photoconductor
22a drive roller
22b drive roller
23 Charger
24 Image exposure source
25 Transfer Charger
26 Pre-cleaning exposure
27 Cleaning brush
28 Static elimination light source
30 Photoconductor
31 Transfer roller
32 developing roller
33 Image exposure unit
34 Charging member
35 Cleaning brush

Claims (21)

An electrophotographic photosensitive member having at least a photosensitive layer and a surface protective layer on a conductive support, wherein the surface protective layer contains at least a urethane resin obtained by crosslinking and polymerizing isocyanate and a polyol, and a polymer charge transport material, An electrophotographic photosensitive member, wherein the transport material is a polycarbonate polymer having a triphenylamine skeleton in a main chain and / or a side chain. The electrophotographic photoreceptor according to claim 1, wherein the isocyanate has three or more functional groups. The electrophotographic photosensitive member according to claim 1, wherein the polyol is a polyol having the following structure.

(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and n = 1 to 5.) The electrophotographic photoreceptor according to claim 3, wherein the polyol has a molecular weight of 100 or more and 150 or less. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 1 in a branched chain.

In the formula, R ₁ , R ₂ , and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted. A substituted aryl group, o, p, and q each independently represent an integer of 0 to 4, k and j each represent a composition, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n represents the number of repeating units. And an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.

In the formula, R ₁₀₁ and R ₁₀₂ each independently represent a substituted or unsubstituted alkyl group, aryl group, or halogen atom. l, m is an integer of 0 to 4, Y is a single bond, a linear C1-12, branched or cyclic alkylene group, -O -, - S -, - SO -, - SO 2 - , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or

(In the formula, a represents an integer of 1 to 20, b represents an integer of 1 to 2,000, and R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group.) Here, R ₁₀₁ and R ₁₀₂ and R ₁₀₃ and R ₁₀₄ may be the same or different. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein the polymer charge transport material comprises a polycarbonate having a triarylamine structure represented by the following general formula 2 in a branched chain.

In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 3 in a branched chain.

In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ , and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the polymer charge transport material comprises a polycarbonate having a triarylamine structure represented by the following general formula 4 in a branched chain.

In the formula, R ₁₁ and R ₁₂ represent a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , and Ar ₉ represent the same or different arylene groups, and s represents an integer of 1 to 5. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 8, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 5 in its main chain.

In the formula, R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ , and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or substituted or unsubstituted. Represents a substituted vinylene group. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 9, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 6 in a branched chain.

In the formula, R ₁₅ , R ₁₆ , R ₁₇ , and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , and Ar ₁₆ are the same or different arylene groups, and Y ₁ , Y ₂ , and Y ₃ are A single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group may be the same or different. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 10, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 7 in its main chain.

In the formula, R ₁₉ and R ₂₀ represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 11, wherein the polymer charge transport material contains a polycarbonate having a triarylamine structure represented by the following general formula 8 in the main chain.

In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. 13. The electrophotographic photoreceptor according to claim 1, wherein the polymer charge transporting material contains a polycarbonate having a triarylamine structure represented by the following general formula 9 in a branched chain.

In the formula, R ₂₂ , R ₂₃ , R ₂₄ , and R ₂₅ represent a substituted or unsubstituted aryl group, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , and Ar ₂₈ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. 14. The electrophotographic photoreceptor according to claim 1, wherein the polymer charge transporting material contains a polycarbonate having a triarylamine structure represented by the following general formula 10 in the main chain.

In the formula, R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ , and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as in the case of the general formula 1. The electrophotographic photoreceptor according to any one of claims 1 to 14, wherein the surface protective layer has a thickness of 1.0 to 8.0 µm. 16. The electrophotographic photosensitive member according to claim 1, wherein the image forming apparatus includes at least a charging unit, an image exposing unit, a developing unit, a transfer unit, and an electrophotographic photosensitive member. An image forming apparatus using: 17. The image forming apparatus according to claim 16, wherein the writing of the electrostatic latent image on the photoconductor is performed by using an LD or an LED of the image exposure unit. 18. The image forming apparatus according to claim 16, wherein the charging unit includes a charging member in contact with or close to the photosensitive member. 19. The image forming apparatus according to claim 16, wherein an alternating current component is superimposed on a direct current component of the charging member to charge the photosensitive member. 16. A process cartridge in which at least one of a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit is integrated with an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is any one of claims 1 to 15. 4. A process cartridge, which is the electrophotographic photosensitive member according to 1. An image forming method using at least a charging unit, an image exposing unit, a developing unit, a transferring unit, and the electrophotographic photosensitive member according to claim 1.

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