JP4223671B2 - Electrophotographic photosensitive member, electrophotographic method, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Description

（式中ｎは自然数を表わし、８〜２５の数である）
【００１９】
【化４】

」によって達成される。
【００２１】
また、上記課題は、本発明の（２）「電子写真感光体に、少なくとも帯電、画像露光、現像、転写、クリーニング、除電を繰返し行なう電子写真方法であって、該電子写真感光体が前記第（１）項に記載のものであることを特徴とする電子写真方法」、（３）「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電子写真装置であって、該電子写真感光体が前記第（１）項に記載の電子写真感光体であることを特徴とする電子写真装置」、（４）「少なくとも電子写真感光体を具備してなる電子写真装置用プロセスカートリッジであって、該電子写真感光体が前記第（１）項に記載のものであることを特徴とする電子写真装置および電子写真装置用プロセスカートリッジ」により達成される。
【００２２】
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、導電性支持体（３１）上に、電荷発生物質と電荷輸送物質を主成分とする感光層（３３）が設けられ、更に感光層表面に保護層（３９）が設けられてなる。この場合、感光層（３３）には有機硫黄系化合物が含有され、保護層（３９）にはフィラー、及びヒンダードアミンとヒンダードフェノールの両構造を有する化合物が含有されてなる。
図２は、導電性支持体（３１）上に、電荷発生物質を主成分とする電荷発生層（３５）と電荷輸送物質を主成分とする電荷輸送層（３７）とが積層された感光層をもつ構成をとっており、更に電荷輸送層上に保護層（３９）が設けられてなる。この場合、電荷発生層（３５）、電荷輸送層（３７）のいずれか、もしくは両方には有機硫黄系化合物が含有され、保護層（３９）にはフィラー、及びヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物が含有されてなる。
【００２３】
図３は、導電性支持体（３１）上に、電荷輸送物質を主成分とする電荷輸送層（３７）と電荷発生物質を主成分とする電荷発生層（３５）とが積層された構成をとっており、更に電荷発生層上に保護層（３９）が設けられてなる。この場合、電荷発生層（３５）、電荷輸送層（３７）のいずれか、もしくは両方には有機硫黄系化合物が含有され、保護層（３９）にはフィラー、及びヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物が含有されてなる。
【００２４】
導電性支持体（３１）としては、体積抵抗１０¹⁰Ω・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（３１）として用いることができる。
【００２５】
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についても、本発明の導電性支持体（３１）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あげられる。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。
【００２６】
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、テフロンなどの素材に、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（３１）として良好に用いることができる。
【００２７】
次に、感光層について説明する。
本発明の感光体における感光層には有機硫黄系化合物が含有される。この感光層中に含まれる有機硫黄系化合物としては、硫黄原子を含み酸化防止機能を有するものであれば特に限定されるものではないが、特に、下記一般式（Ｉ）で表わされる構造のものが好ましい。
【００２８】
【化５】

（式中ｎは自然数を表わし、８〜２５の数である）
ｎが８より小さいと昇華しやすくｎが２５より大きいと感光層中での相溶性が悪化し、析出するようになってしまう。一般式（Ｉ）で表わされる有機硫黄系化合物の具体例を以下に示すが本発明はこれらの化合物に限定されるものではない。
【００２９】
【化６】

【００３０】
【化７】

【００３１】
【化８】

【００３２】
【化９】

【００３３】
【化１０】

【００３４】
【化１１】

【００３５】
本発明で用いられる感光体の感光層は単層構成でも積層構成でもよいが、説明の都合上、先ず電荷発生層（３５）と電荷輸送層（３７）で構成される積層構成の場合から述べる。
電荷発生層（３５）は、電荷発生物質を主成分とする層である。電荷発生層（３５）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。
電荷発生層（３５）は、電荷発生物質を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。
【００３６】
必要に応じて電荷発生層（３５）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、シリコーン樹脂、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。結着樹脂の添加は、分散前あるいは分散後どちらでも構わない。
【００３７】
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、エチルセルソルブ、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。これらは単独で用いても２種以上混合して用いてもよい。
【００３８】
電荷発生層（３５）は、電荷発生物質、溶媒及び結着樹脂を主成分とするが、その中には、増感剤、分散剤、界面活性剤、シリコーンオイル等が含まれていても良い。
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（３５）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。
【００３９】
電荷輸送層（３７）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、必要により単独あるいは２種以上の可塑剤、レベリング剤等を添加することもできる。
【００４０】
電荷輸送物質には、正孔輸送物質と電子輸送物質とがある。
電子輸送物質としては、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。
【００４１】
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。
【００４２】
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、アルキッド樹脂等の熱可塑性または熱硬化性樹脂が挙げられる。
【００４３】
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。
【００４４】
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。これらは単独で使用しても２種以上混合して使用しても良い。
【００４５】
感光層が上記のような積層構成をとる場合、感光層中に含有されるべき有機硫黄系化合物は電荷輸送層に含有せしめるほうがより好ましい。
【００４６】
次に、感光層が単層構成の場合について述べる。
単層の感光層には、上述した電荷発生物質、電荷輸送物質、結着樹脂などが全て使用できる。
感光層は、電荷発生物質および電荷輸送物質、上述の硫黄系化合物、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。また、必要により可塑剤やレベリング剤等を添加することもできる。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。感光層は、電荷発生物質、結着樹脂を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、リングコートなどで塗工して形成できる。感光層の膜厚は、５〜２５μｍ程度が適当である。
【００４７】
次に、保護層（３９）について説明する。
保護層（３９）は、フィラー材料を結着樹脂とともに適当な溶剤を介して分散せしめるとともに、ヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物を添加、溶解させ、これを感光層上に塗布、乾燥することにより形成される。感光体の最表層である保護層にヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物を併用することにより、長期間の繰り返し使用によるオゾン等の活性ガスから感光体の劣化を抑制するため、耐摩耗性だけでなく画像安定性を飛躍的に向上させることが可能となる。
【００４８】
ここでいうヒンダードアミン構造とは、アミノ窒素原子近傍に嵩高い原子団が存在する構造を示す。いわゆる芳香族アミン、脂肪族アミン系物質もこれに該当する。またヒンダードフェノール構造とは、フェノール性水酸基のオルト位に嵩高い原子団が存在する構造を示す。これら両構造を有する化合物の作用のメカニズムの詳細は明らかになっていないが、嵩高い原子団が存在することにより生じる立体障害により、アミノ窒素原子、フェノール性水酸基の熱振動を抑制し、外部からの活性ガスなどの影響を抑制すると推定される。
【００４９】
ヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物の例としては種々のものがあり、その全てを用いることができるが、中でも下記構造式（II）で表わされる１−［２−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕エチル］−４−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕−２，２，６，６−テトラメチルピリジンが好ましい。
【００５０】
【化１２】

【００５１】
フィラー材料と、ヒンダードアミン構造とヒンダードフェノール構造の両構造を有する化合物の比率は、フィラーに対して０．０１ｗｔ％〜５０ｗｔ％、さらに好ましくは０．１ｗｔ％〜２０ｗｔ％であるが、添加量を必要以上に多くすると、耐摩耗性の低下が現れることがあり、添加量が少なすぎると異常画像抑制効果が十分に発揮されなくなる。
【００５２】
保護層（３９）に使用される結着樹脂材料としては、ＡＢＳ樹脂、ＡＣＳ樹脂、オレフィン−ビニルモノマー共重合体、塩素化ポリエーテル、アリール樹脂、フェノール樹脂、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアクリレート、ポリアリルスルホン、ポリブチレン、ポリブチレンテレフタレート、ポリカーボネート、ポリエーテルスルホン、ポリエチレン、ポリエチレンテレフタレート、ポリイミド、アクリル樹脂、ポリメチルベンテン、ポリプロピレン、ポリフェニレンオキシド、ポリスルホン、ポリスチレン、ポリアリレート、ＡＳ樹脂、ブタジエン−スチレン共重合体、ポリウレタン、ポリ塩化ビニル、ポリ塩化ビニリデン、エポキシ樹脂等の樹脂が挙げられる。フィラーの分散性、残留電位、塗膜欠陥の点から、特に、ポリカーボネートあるいはポリアリレートが有効かつ有用である。
【００５３】
また、本発明で使用されるフィラーとは、一般に有機性フィラーと無機性フィラーに分類される。有機性フィラー材料としては、ポリテトラフルオロエチレンのようなフッ素樹脂粉末、シリコ−ン樹脂粉末、ａ−カ−ボン粉末等が挙げられ、無機性フィラー材料としては、銅、スズ、アルミニウム、インジウムなどの金属粉末、シリカ、酸化錫、酸化亜鉛、酸化チタン、アルミナ、酸化ジルコニウム、酸化インジウム、酸化アンチモン、酸化ビスマス、酸化カルシウム、アンチモンをドープした酸化錫、錫をドープした酸化インジウム等の金属酸化物、フッ化錫、フッ化カルシウム、フッ化アルミニウム等の金属フッ化物、チタン酸カリウム、窒化硼素などが挙げられる。これらのフィラーの中で、フィラーの硬度の点から無機フィラーである無機顔料を用いることが耐摩耗性の向上に対し有利である。
【００５４】
さらに、これらのフィラーは少なくとも一種の表面処理剤で表面処理させることが可能であり、そうすることがフィラーの分散性の面から好ましい。フィラーの分散性の低下は残留電位の上昇だけでなく、塗膜の透明性の低下や塗膜欠陥の発生、さらには耐摩耗性の低下をも引き起こすため、高耐久化あるいは高画質化を妨げる大きな問題に発展する可能性がある。表面処理剤としては、従来用いられている表面処理剤すべてを使用することができるが、フィラーの絶縁性を維持できる表面処理剤が好ましい。例えば、チタネート系カップリング剤、アルミニウム系カップリング剤、ジルコアルミネート系カップリング剤、高級脂肪酸等、あるいはこれらとシランカップリング剤との混合処理や、Ａｌ₂Ｏ₃、ＴｉＯ₂、ＺｒＯ₂、シリコーン、ステアリン酸アルミニウム等、あるいはそれらの混合処理がフィラーの分散性及び画像ボケの点からより好ましい。シランカップリング剤による処理は、画像ボケの影響が強くなるが、上記の表面処理剤とシランカップリング剤との混合処理を施すことにより、その影響を抑制できる場合がある。表面処理量については、用いるフィラーの平均一次粒径によって異なるが、３〜３０ｗｔ％が適しており、５〜２０ｗｔ％がより好ましい。表面処理量がこれよりも少ないとフィラーの分散効果が得られず、また多すぎると残留電位の著しい上昇を引き起こす。
【００５５】
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、電荷輸送層（３７）で使用されるすべての溶剤を使用することができる。但し、分散時には粘度が高い溶剤が好ましいが、塗工時には揮発性が高い溶剤が好ましい。これらの条件を満たす溶剤がない場合には、各々の物性を有する溶剤を２種以上混合させて使用することが可能であり、フィラーの分散性や残留電位に対して大きな効果を有する場合がある。
【００５６】
また、保護層に電荷輸送層（３７）で挙げた電荷輸送物質を添加することは、残留電位の低減及び画質向上に対して有効かつ有用である。その際、保護層中に含有される電荷輸送物質のイオン化ポテンシャル（Ｉｐ）が、感光層中に含有される電荷輸送物質のＩｐと同じか、より小さくなるような電荷輸送物質を保護層に添加することによって、保護層への電荷注入性が向上することにより、残留電位をより低減できる効果を有する。なお、イオン化ポテンシャルＩｐは、分光学的に求める方法、電気化学的に求める方法等、種々の方法を用いて測定することができる。
【００５７】
前記フィラー材料は、ボールミル、アトライター、サンドミル、超音波などの従来方法を用いて分散することができる。この中でも、外界からの不純物の混入が少ないボールミルによる分散が、分散性の点からより好ましい。使用されるメディアの材質については、従来使用されているジルコニア、アルミナ、メノウ等すべてのメディアを使用することができる。
【００５８】
また、フィラーの平均一次粒径は、０．０１〜０．５μｍであることが、保護層の光透過率や耐摩耗性の点から好ましい。フィラーの平均一次粒径が０．０１μｍ以下の場合は、耐摩耗性の低下、分散性の低下等を引き起こし、０．５μｍ以上の場合には、フィラーの沈降性が促進されたり、トナーのフィルミングが発生したりする可能性がある。
【００５９】
保護層の形成法としては、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、リングコート等の従来方法を用いることができるが、特に、塗膜の均一性の面からスプレーコートがより好ましい。さらに、保護層の必要膜厚を一度で塗工し、保護層を形成することも可能であるが、２回以上重ねて塗工し、保護層を多層にするほうが、膜中におけるフィラーの均一性の面からより好ましい。そうすることによって、残留電位の低減、解像度の向上、及び耐摩耗性の向上に対し、より一層の効果が得られる。なお、保護層の厚さは０．１〜１０μｍ程度が適当である。
【００６０】
本発明の感光体においては、導電性支持体（３１）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。
【００６１】
これらの下引き層は、前述の感光層の如く適当な溶媒及び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、Ａｌ₂Ｏ₃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ＳｉＯ₂、ＳｎＯ₂、ＴｉＯ₂、ＩＴＯ、ＣｅＯ₂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。
【００６２】
【発明の実施の形態】
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及び電子写真装置を説明するための概略図であり、下記のような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。帯電チャージャー（３）、転写前チャージャー（７）、転写チャージャー（１０）、分離チャージャー（１１）、クリーニング前チャージャー（１３）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）、帯電ローラ等が用いられ、公知の手段がすべて使用可能である。
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。
【００６３】
また、画像露光部（５）、除電ランプ（２）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。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。
【００６４】
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。
【００６５】
さて、現像ユニット（６）により感光体（１）上に現像されたトナーは、転写紙（９）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（１４）およびブレード（１５）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。
【００６６】
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。
【００６７】
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。
【００６８】
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。
【００６９】
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。
【００７０】
【実施例】
以下、本発明について実施例を挙げて説明するが、本発明が実施例により制約を受けるものではない。なお、部はすべて重量部である。なお、電荷輸送物質のイオン化ポテンシャル（Ｉｐ）は、表面分析装置（理研計器製、ＡＣ−１）にて測定した。
（実施例１）
アルミニウムシリンダー上に下記組成の下引き層塗工液、電荷発生層塗工液、および電荷輸送層塗工液を、浸漬塗工によって順次塗布、乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２６μｍの電荷輸送層を形成した。
【００７１】
＜下引き層塗工液＞
二酸化チタン粉末 ４００部
メラミン樹脂 ４０部
アルキッド樹脂 ６０部
２−ブタノン ５００部
【００７２】
＜電荷発生層塗工液＞
下記構造のビスアゾ顔料 １２部
【００７３】
【化１３】

ポリビニルブチラール ５部
２−ブタノン ２００部
シクロヘキサノン ４００部
【００７４】
＜電荷輸送層塗工液＞
ポリカーボネート（Ｚポリカ、帝人化成製） １０部
下記構造式の電荷輸送物質（Ｉｐ：５．４ｅＶ） １０部
【００７５】
【化１４】

下記構造式の有機硫黄系化合物（住友化学工業製） ０．１５部
【００７６】
【化１５】

テトラヒドロフラン １００部
電荷輸送層上にさらに、下記組成の保護層塗工液をスプレー塗工法によって約１．５μｍの保護層を形成し、実施例１の電子写真感光体を作製した。
【００７７】
＜保護層塗工液＞
アルミナ（平均一次粒径：０．３μｍ、住友化学工業製） ３部
下記構造式のヒンダードアミン構造と
ヒンダードフェノール構造を有する化合物 ０．２４部
【００７８】
【化１６】

下記構造式の電荷輸送物質（Ｉｐ：５．４ｅＶ） ４部
【００７９】
【化１７】

ポリカーボネート（Ｚポリカ、帝人化成製） ５．５部
テトラヒドロフラン ２２０部
シクロヘキサノン ８０部
【００８０】
（実施例２）
実施例１において、電荷輸送層塗工液の有機硫黄系化合物を下記の有機硫黄系化合物に変更した以外は、すべて実施例１と同様にして、実施例２の電子写真感光体を作製した。
下記構造式の有機硫黄系化合物（住友化学工業製） ０．１５部
【００８１】
【化１８】

【００８２】
（参考例１）
実施例１において、電荷輸送層塗工液の有機硫黄系化合物を下記の有機硫黄系化合物に変更した以外は、すべて実施例１と同様にして、参考例１の電子写真感光体を作製した。
下記構造式の有機硫黄系化合物（住友化学工業製） ０．１５部
【００８３】
【化１９】

【００８４】
（参考例２）
実施例１において、保護層塗工液のヒンダードアミン構造とヒンダードフェノール構造を有する化合物を、下記構造式のヒンダードアミン構造とヒンダードフェノール構造を有する化合物とした以外は、すべて実施例１と同様にして、参考例２の電子写真感光体を作製した。
下記構造式のヒンダードアミン構造とヒンダードフェノール構造を有する化合物
０．２２部
【００８５】
【化２０】

【００８６】
（実施例３）
実施例１において、保護層に含有されるフィラーを下記の材料に変更した以外は、すべて実施例１と同様にして実施例３の電子写真感光体を作製した。
酸化チタン（平均一次粒径０．３μｍ、石原産業製） ３部
【００８７】
（実施例４）
実施例１において、保護層に含有されるフィラーを下記の材料に変更した以外は、すべて実施例１と同様にして実施例４の電子写真感光体を作製した。
アルミナ（平均一次粒径０．６μｍ、石原産業製） ３部
【００８８】
（実施例５）
実施例１において、保護層に含有されるフィラーを下記の材料に変更した以外は、すべて実施例１と同様にして、実施例５の電子写真感光体を作製した。
シリカ（平均粒径０．０１５μｍ、信越シリコーン製） ２部
【００８９】
（実施例６）
実施例１において、保護層に含有される電荷輸送物質を下記の材料に変更した以外は、すべて実施例１と同様にして、実施例６の電子写真感光体を作製した。
下記構造式の電荷輸送物質（Ｉｐ：５．３ｅＶ） １０部
【００９０】
【化２１】

【００９１】
（実施例７）
実施例１において、保護層に含有される電荷輸送物質を下記の材料に変更した以外は、すべて実施例１と同様にして、実施例７の電子写真感光体を作製した。
下記構造式の電荷輸送物質（Ｉｐ：５．５ｅＶ） １０部
【００９２】
【化２２】

【００９３】
（実施例８）
実施例１において、保護層に含有されるバインダー樹脂を下記の材料に変更した以外は、すべて実施例１と同様にして、実施例８の電子写真感光体を作製した。
ポリアリレート樹脂（Ｕポリマー、ユニチカ製） １０部
【００９４】
（実施例９）
実施例１において、電荷発生層塗工液、電荷輸送層塗工液及び保護層塗工液を下記のものに変更した以外は、実施例１と同様にして、実施例９の電子写真感光体を作製した。
【００９５】
＜電荷発生層塗工液＞
Ｙ型チタニルフタロシアニン ９部
ポリビニルブチラール ５部
２−ブタノン ４５０部
【００９６】
＜電荷輸送層塗工液＞
Ｃ型ポリカーボネート １０部
下記構造式の電荷輸送物質（Ｉｐ：５．３ｅＶ） ８部
【００９７】
【化２３】

下記構造式の有機硫黄系化合物（住友化学工業製） ０．１５部
【００９８】
【化２４】

トルエン ７０部
【００９９】
＜保護層塗工液＞
アルミナ処理酸化チタン
（平均一次粒径０．０３５μｍ、テイカ製） ３部
メタクリル酸／メチルメタクリレート共重合体
（酸価５０ｍｇＫＯＨ／ｇ） ０．５部
Ｃ型ポリカーボネート（帝人化成製） ５．５部
下記構造式のヒンダードアミン構造と
ヒンダードフェノール構造を有する化合物 ０．２４部
【０１００】
【化２５】

下記構造式の電荷輸送物質（Ｉｐ：５．３ｅＶ） ４部
【０１０１】
【化２６】

テトラヒドロフラン ２５０部
シクロヘキサノン ５０部
【０１０２】
（比較例１）
実施例１において、保護層を設けなかった以外は、すべて実施例１と同様にして、比較例１の電子写真感光体を作製した。
【０１０３】
（比較例２）
実施例１において、保護層塗工液にアルミナを加えなかった以外は、すべて実施例１と同様にして、比較例２の電子写真感光体を作製した。
【０１０４】
（比較例３）
実施例１において、保護層塗工液にヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えず、電荷輸送層塗工液に有機硫黄化合物を加えなかった以外は、すべて実施例１と同様にして、比較例３の電子写真感光体を作製した。
【０１０５】
（比較例４）
実施例１において、電荷輸送層塗工液に有機硫黄化合物を加えなかった以外は、すべて実施例１と同様にして、比較例４の電子写真感光体を作製した。
【０１０６】
（比較例５）
実施例１において、保護層塗工液にヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えなかった以外は、すべて実施例１と同様にして、比較例５の電子写真感光体を作製した。
【０１０７】
（比較例６）
実施例１において、電荷輸送層塗工液に有機硫黄化合物を加えずに、代わりに下記構造式で表わされる化合物を同量添加した以外は、すべて実施例１と同様にして、比較例６の電子写真感光体を作製した。
【０１０８】
【化２７】

【０１０９】
（比較例７）
実施例１において、電荷輸送層塗工液に有機硫黄化合物を加えずに、代わりに下記構造式で表わされる化合物を同量添加した以外は、すべて実施例１と同様にして、比較例７の電子写真感光体を作製した。
【０１１０】
【化２８】

【０１１１】
（比較例８）
実施例１において、保護層塗工液にヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えず、代わりに下記構造式で表わされる化合物を同量添加した以外は、すべて実施例１と同様にして、比較例８の電子写真感光体を作製した。
【０１１２】
【化２９】

【０１１３】
（比較例９）
実施例１において、保護層塗工液にヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えず、代わりに下記構造式で表わされる化合物を同量添加した以外は、すべて実施例１と同様にして、比較例９の電子写真感光体を作製した。
【０１１４】
【化３０】

【０１１５】
（比較例１０）
実施例１において、電荷輸送層塗工液に有機硫黄化合物を加えず、代わりに実施例１の保護層塗工液に用いたヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えた以外、すべて実施例１と同様にして、比較例１０の電子写真感光体を作製した。
【０１１６】
（比較例１１）
実施例１において、保護槽塗工液にヒンダードアミン構造とヒンダードフェノール構造を有する化合物を加えず、代わりに実施例１の電荷輸送層塗工液に用いた有機硫黄化合物を加えた以外、すべて実施例１と同様にして、比較例１０の電子写真感光体を作製した。
【０１１７】
以上のように作製した実施例１〜９、参考例１〜２の電子写真感光体、及び比較例１〜１１の電子写真感光体を電子写真プロセス用カートリッジ（ただし、クリーニング前露光はなし）に装着し、画像露光光源を６５５ｎｍの半導体レーザーを用いたリコー製レーザープリンタ改造機にて、連続してまず１万枚の印刷を行ない、その際、初期画像及び１万枚印刷後の暗部電位、明部電位、画像品質について評価を行なった。暗部電位、明部電位、画像品質については以下のようにして評価した。
暗部電位：一次帯電の後、現像部位置まで移動した際の感光体表面電位
明部電位：一時帯電の後、画像露光（全面露光）を受け、現像部位置まで移動した際の感光体表面電位
画像品質：出力画像の画像濃度、細線再現性、文字かすれ、解像度、地肌汚れなどを総合的に評価
また、１万枚印刷後、感光体をオゾン、ＮＯｘガス濃度それぞれ１０ｐｐｍの環境に１０日間ずつ放置するガス曝露試験を行ない、その後上記改造機にて同様に暗部電位、明部電位、画像品質について評価を行った。
さらに、１０万枚まで印刷後に暗部電位、明部電位、画像品質についての評価をおこなった。また、１０万枚印刷後には膜厚測定を行ない、印刷前後の膜厚差より摩耗量の評価を行なった。
なお、異常画像などを発生した場合は以降の評価を中止した。結果を表１に示す。
【０１１８】
【表１】

表１の評価結果より、実施例の感光体は暗部電位、明部電位ともに変化が少なく優れた静電安定性を示し、活性ガスに対しても優れた化学的安定性を示し、かつ高い耐摩耗性を有しており、安定して高画質画像が得られることがわかる。
【０１１９】
【発明の効果】
以上、詳細かつ具体的な説明から明らかなように、本発明は繰り返しの使用にわたっても残留電位上昇、あるいは画像ボケなどの異常画像が発生せず、長期にわたり高画質な画像が安定に得られる高耐久の感光体を提供し、また、それらの感光体を用いることにより、感光体の交換が不要で、かつ高速印刷あるいは感光体の小径化に伴う装置の小型化を実現し、さらに繰り返し使用においても高画質画像が安定に得られる電子写真方法、電子写真装置、ならびに電子写真用プロセスカートリッジを提供するという極めてすぐれた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の断面を概略的に示した図である。
【図２】本発明の電子写真感光体の断面を概略的に示した別の図である。
【図３】本発明の電子写真感光体の断面を概略的に示した更に別の図である。
【図４】本発明の電子写真装置及び電子写真装置用プロセスカートリッジの概略図である。
【図５】本発明の他の電子写真装置の概略図である。
【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
２ 除電ランプ
３ 帯電チャージャ
４ イレーサ
５ 画像露光部
６ 現像ユニット
７ 転写前チャージャ
８ レジストローラ
９ 転写紙
１０ 転写チャージャ
１１ 分離チャージャ
１２ 分離爪
１３ クリーニング前チャージャ
１４ ファーブラシ
１５ クリーニングブラシ
１６ 感光体
１７ 帯電チャージャ
１８ クリーニングブラシ
１９ 画像露光部
２０ 現像ローラ
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
３１ 導電性支持体
３３ 感光層
３５ 電荷発生層
３７ 電荷輸送層
３９ 保護層[0001]
[Industrial application fields]
The present invention relates to an electrophotographic photoreceptor having high durability and realizing high image quality. In addition, the present invention relates to an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge using those photoconductors.
[0002]
[Prior art]
In recent years, there has been a remarkable development in information processing system machines using electrophotography. In particular, laser printers and digital copying machines that convert information into digital signals and record information using light have significantly improved print quality and reliability. Furthermore, they have been applied to laser printers or digital copiers capable of full-color printing by fusing with high-speed technology. From such a background, it is particularly important to achieve both high image quality and high durability as a required photoreceptor function.
[0003]
As photoconductors used in these electrophotographic laser printers, digital copiers, etc., those using organic photosensitive materials are generally widely applied for reasons such as cost, productivity and non-pollution. Yes. The organic electrophotographic photoreceptor includes a photoconductive resin typified by polyvinylcarbazole (PVK), a charge transfer complex type typified by PVK-TNF (2,4,7-trinitrofluorenone), Known are a pigment dispersion type typified by a phthalocyanine binder, and a function separation type photoreceptor using a combination of a charge generation material and a charge transport material.
[0004]
The mechanism of electrostatic latent image formation in the function-separated type photoconductor is that when the photoconductor is charged and then irradiated with light, the light passes through the charge transport layer and is absorbed by the charge generation material in the charge generation layer to generate a charge. . The charges generated thereby are injected into the charge transport layer at the interface between the charge generation layer and the charge transport layer, and further moved through the charge transport layer by an electric field, thereby neutralizing the surface charge of the photoconductor to form an electrostatic latent image. To form.
[0005]
However, organic photoconductors are prone to film scraping due to repeated use, and when the photosensitive layer is scraped, soiling due to a decrease in the charged potential of the photoconductor, deterioration of photosensitivity, scratches on the surface of the photoconductor, etc. However, there is a strong tendency to promote deterioration of image quality such as a reduction in image density, and the wear resistance of the photoreceptor has been cited as a major issue. Further, in recent years, the increase in the durability of the photoconductor has become an even more important issue due to the reduction in the diameter of the photoconductor due to the increase in the speed of the electrophotographic apparatus or the downsizing of the apparatus.
[0006]
As a method for realizing high durability of the photoconductor, a method of providing a protective layer on the outermost surface of the photoconductor and imparting lubricity to the protective layer, curing, or adding a filler is widely known. .
In particular, the method of containing a filler in the protective layer is one of the very effective methods for enhancing the durability of the photoreceptor. However, by including a filler in the protective layer, mechanical durability such as improved wear resistance is improved, but in the so-called electrophotographic system, not only mechanical durability but also charging potential by repeated charging, exposure, etc. Also, electrical or optical durability such as stability of the exposure portion potential is very important. This is because even if the mechanical durability is improved and the amount of film scraping is greatly reduced, if the charged potential decreases or the exposed area potential increases, sufficient electrostatic contrast cannot be obtained and image quality deteriorates. It is because it produces.
[0007]
As a method for suppressing such a decrease in chargeability and stabilizing the charging potential, a method of adding an antioxidant to the photosensitive layer is used as described in JP-A-57-12244.
Japanese Patent Publication No. 5-67230, Japanese Patent Publication No. 6-75203, Japanese Patent Publication No. 6-75204, Japanese Patent Publication No. 6-23853, and Japanese Patent Publication No. 6-90520 are disclosed. In order to impart durability, it is described that a compound having a hindered amine structural unit or a compound having a hindered phenol structural unit is added.
However, when an antioxidant or an antioxidant compound is added to the photosensitive layer in this way, in order to achieve a sufficient effect, a certain increase in the residual potential and avoiding an increase in the exposed portion potential in the electrophotographic apparatus are avoided. I couldn't. Nevertheless, in the case of the photosensitive layer alone, although there is a range of increase in residual potential that can withstand practical use, the above protective layer containing filler is applied on the photosensitive layer for the purpose of improving wear resistance, that is, improving mechanical durability. If it is provided, a problem arises that the residual potential further increases. When a protective layer containing this filler is provided, it is greatly affected by the type of filler, and when a filler with high electrical insulation is contained, the resistance becomes higher and the residual potential is higher than when no protective layer is provided. The rise of is noticeable. These increases in the residual potential are greatly affected by an increase in resistance caused by the inclusion of the filler and an increase in charge trap sites. The increase in residual potential, which is often seen when using a highly insulating filler, leads to a high exposure area potential in the electrophotographic apparatus, leading to a decrease in image density and gradation.
[0008]
In order to compensate for this, it is necessary to increase the dark part potential. However, if the dark part potential is increased, the electric field strength increases, which not only causes image defects such as background stains, but also reduces the life of the photoreceptor. Connected. On the other hand, as a method for suppressing an increase in residual potential in the prior art, a method in which a protective layer is a photoconductive layer (Japanese Patent Publication No. 44-834, Japanese Patent Publication No. 43-16198, Japanese Patent Publication No. 49-10258, etc.) Is disclosed. However, since the amount of light reaching the photosensitive layer is reduced by the absorption of light by the protective layer, there arises a problem that the sensitivity of the photosensitive member is lowered, and the effect is slight.
[0009]
On the other hand, when the conductive filler is used, the increase in the residual potential is reduced, but the dark resistance is reduced, or when the image is output, so-called image blur occurs, in which the outline of the image is blurred and the resolution is lowered. , Image quality deteriorates.
Therefore, in the prior art, a filler having a high insulating property is difficult to use, and a filler having a low insulating property that is relatively less affected by the residual potential is used. For image blurring caused by this, means for mounting a drum heater for heating the photosensitive member is used. Although the occurrence of image blur can be suppressed by heating the photoconductor, the diameter of the photoconductor must be large in order to mount a drum heater. It cannot be applied to a photoconductor, and it has been difficult to improve the durability of a small-diameter photoconductor. In addition, the installation of a drum heater inevitably increases the size of the device, which significantly increases power consumption and requires a lot of time to start up the device. It was.
[0010]
As another means for suppressing an increase in residual potential due to the provision of a protective layer, a method of adding a Lewis acid or the like in the protective layer (Japanese Patent Laid-Open No. 53-133444), a method of adding an organic protonic acid to the protective layer (Japanese Patent Laid-Open No. 55-157748), a method of containing an electron accepting substance (Japanese Patent Laid-Open No. 2-4275), a method of containing a wax having an acid value of 5 (mgKOH / g) or less (Japanese Patent Laid-Open No. 2000-2000) No. 66434). These methods improve the charge injection property at the protective layer / charge transport layer interface, and the charge can easily reach the surface by forming a low resistance portion in the protective layer. It is thought that Although this method has an effect of reducing the residual potential, it tends to cause image blur, and has a side effect in which the influence on the image is noticeable.
[0011]
In addition, even when mechanical durability such as wear resistance is improved, an active gas such as ozone generated at the time of discharging during charging and an active gas existing in the surrounding environment, such as a heating appliance, when repeatedly used for a long period of time In many cases, the photoconductor is exposed to a nitrogen oxide gas generated from the above, and the surface of the photoconductor is affected to cause image deterioration.
This phenomenon is particularly caused when the wear resistance is greatly improved, that is, in a photoconductor having a greatly reduced film scraping amount, as the conventional photoconductor with a large amount of wear wears from the surface sequentially, It is not possible to expect an effect that the active gas, the corona product adhering to it, and the outermost surface contaminated by the reaction and the like are gradually worn and polished, so that it is automatically refaced to the new outermost surface. Therefore, there is a problem that image deterioration due to such surface contamination, that is, an abnormal image is likely to occur.
That is, a photoconductor having high wear resistance has a problem that image deterioration and abnormal images are more likely to occur than a photoconductor that does not.
In other words, simply improving the wear resistance does not make it possible to increase the durability of the photoreceptor, but not only mechanical durability such as improved wear resistance, but also electrostatic durability such as continuous residual potential suppression. Unless the durability and chemical durability such as stability against corona products and active gas are improved, it cannot be said that the durability of the photoreceptor has been improved.
[0012]
As a countermeasure against this, it is effective to add an antioxidant to the protective layer, which is the outermost layer. However, as just described, the protective layer containing the filler is applied to the photosensitive layer with the addition of the antioxidant. If it is provided, the residual potential is significantly increased. Therefore, a method of adding an antioxidant only to the protective layer containing a filler without adding an antioxidant to the photosensitive layer can be considered. However, in this case, the addition of a small amount causes insufficient image degradation due to the effect of suppressing charging deterioration and causes image deterioration due to a decrease in charging potential due to repeated use over a long period of time. When the amount is added, the residual potential increases from the beginning, or the binder resin of the protective layer relatively decreases, so that the protective layer becomes brittle, sufficient mechanical strength cannot be obtained, and the amount of film scraping is reduced. It increases, and the meaning of providing a protective layer is lost, which is not suitable for practical use.
In other words, a highly durable electrophotographic photoreceptor that can stably obtain high-quality images even in repeated use over a long period of time, with improved mechanical durability and improved electrical durability and chemical durability, is obtained. It was not done.
[0013]
[Problems to be solved by the present invention]
An object of the present invention is to provide a highly durable photoconductor capable of stably obtaining a high-quality image over a long period of time without causing an increase in residual potential or an abnormal image such as image blur even over repeated use. In addition, by using these photoconductors, it is not necessary to replace the photoconductor, and it is possible to reduce the size of the apparatus due to high-speed printing or reduction in the diameter of the photoconductor. It is an object to provide an electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus that are obtained.
[0014]
[Means to solve the problem]
As a result of intensive studies, the present inventors have obtained an electrophotographic photoreceptor having an excellent wear-resistant filler-dispersed protective layer by containing different specific antioxidants in the photosensitive layer and the protective layer. In addition, it has been found that, even when repeatedly used for a long period of time, the increase in residual potential and the occurrence of abnormal images are suppressed without lowering the charged potential. Specifically, as an antioxidant used in the photosensitive layer, an organic sulfur compound, particularly a compound having a structure represented by the above general formula (I) is added, and the protective layer containing a filler is antioxidant. As an agent, the compound having both the hindered phenol structure and the hindered phenol structure, particularly the compound having the structure of the above structural formula (II), is added as an antioxidant to provide excellent mechanical durability. It was possible to obtain a high-quality image without an abnormal image over a long period of time without loss.
[0015]
This is because a charge transport layer contains an organic sulfur compound that suppresses a decrease in chargeability due to electrostatic repeated fatigue such as charging and exposure, and a photoconductor for active gases such as ozone and nitrogen oxides. This is possible only when an antioxidant having a high effect of suppressing oxidative degradation on the surface layer is contained in the protective layer which is the outermost layer.
[0016]
That is, by satisfying the following constituent requirements, it is possible to achieve both high durability and high image quality, and provide an electrophotographic photosensitive member that can stably obtain high-quality images even for repeated use over a long period of time. In addition, the present invention has been completed by providing an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge capable of stably obtaining a high-quality image even in repeated use.
[0017]
The above-described problems are solved by (1) “electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer containing a filler are sequentially formed on a conductive support. Is a photosensitive layer in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated, the charge transport layer An organic sulfur compound, and the protective layer contains a compound having both a hindered amine structure and a hindered phenol structure in the protective layer, wherein the organic sulfur compound contained in the photosensitive layer is A compound represented by the following general formula (I), a compound having both a hindered amine structure and a hindered phenol structure contained in the protective layer is a compound represented by the following structural formula (II): The electrophotographic photoreceptor, wherein the filler contained in the protective layer is at least one inorganic pigment,
[0018]
[Chemical 3]

(Where n represents a natural number and is a number from 8 to 25)
[0019]
[Formula 4]

To This is achieved.
[0021]
In addition, the above problem is 2 ) “An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeated on an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the above (1). In terms Electrophotographic method characterized in that it is described ", ( 3 ) “An electrophotographic apparatus comprising at least a charging means, an image exposing means, a developing means, a transferring means, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the first (1). In terms An electrophotographic apparatus characterized in that the electrophotographic photosensitive member is described in the above, ( 4 ) “A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the first (1). In terms It is achieved by an electrophotographic apparatus and a process cartridge for an electrophotographic apparatus characterized by what is described.
[0022]
Hereinafter, the electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
In FIG. 1, a photosensitive layer (33) mainly composed of a charge generation material and a charge transport material is provided on a conductive support (31), and a protective layer (39) is further provided on the surface of the photosensitive layer. . In this case, the photosensitive layer (33) contains an organic sulfur compound, and the protective layer (39) contains a filler and a compound having both structures of a hindered amine and a hindered phenol.
FIG. 2 shows a photosensitive layer in which a charge generation layer (35) mainly composed of a charge generation material and a charge transport layer (37) mainly composed of a charge transport material are laminated on a conductive support (31). Further, a protective layer (39) is provided on the charge transport layer. In this case, either or both of the charge generation layer (35) and the charge transport layer (37) contain an organic sulfur compound, and the protective layer (39) has a filler, a hindered amine structure and a hindered phenol structure. A compound having both structures is contained.
[0023]
FIG. 3 shows a structure in which a charge transport layer (37) mainly composed of a charge transport material and a charge generation layer (35) mainly composed of a charge generation material are laminated on a conductive support (31). Further, a protective layer (39) is provided on the charge generation layer. In this case, either or both of the charge generation layer (35) and the charge transport layer (37) contain an organic sulfur compound, and the protective layer (39) has a filler, a hindered amine structure and a hindered phenol structure. A compound having both structures is contained.
[0024]
The conductive support (31) has a volume resistance of 10 ^Ten Films having conductivity of Ω · cm or less, for example, metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxide such as tin oxide, indium oxide, etc. are deposited or sputtered. Shaped or cylindrical plastic, paper-coated, or aluminum, aluminum alloy, nickel, stainless steel, etc., and after making them into tubes by methods such as extrusion and drawing, cutting, superfinishing, polishing, etc. A surface-treated tube or the like can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (31).
[0025]
In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) 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, or metal oxide powder such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is 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-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
[0026]
Furthermore, a conductive layer is formed on a suitable cylindrical substrate by a heat-shrinkable tube containing the conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon. What is provided can also be used favorably as the conductive support (31) of the present invention.
[0027]
Next, the photosensitive layer will be described.
The photosensitive layer in the photoreceptor of the present invention contains an organic sulfur compound. The organic sulfur compound contained in the photosensitive layer is not particularly limited as long as it contains a sulfur atom and has an antioxidant function. Particularly, the organic sulfur compound has a structure represented by the following general formula (I). Is preferred.
[0028]
[Chemical formula 5]

(Where n represents a natural number and is a number from 8 to 25)
If n is less than 8, it will be easily sublimated, and if n is greater than 25, the compatibility in the photosensitive layer will be deteriorated and will precipitate. Specific examples of the organic sulfur compound represented by the general formula (I) are shown below, but the present invention is not limited to these compounds.
[0029]
[Chemical 6]

[0030]
[Chemical 7]

[0031]
[Chemical 8]

[0032]
[Chemical 9]

[0033]
[Chemical Formula 10]

[0034]
Embedded image

[0035]
The photosensitive layer of the photoreceptor used in the present invention may have a single layer structure or a stacked structure. For convenience of explanation, first, the case of a stacked structure including a charge generation layer (35) and a charge transport layer (37) will be described. .
The charge generation layer (35) is a layer mainly composed of a charge generation material. A known charge generation material can be used for the charge generation layer (35), and representative examples thereof include a monoazo pigment, a disazo pigment, a trisazo pigment, a perylene pigment, a perinone pigment, a quinacridone pigment, and a quinone condensation. Polycyclic compounds, squaric acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes and the like are used. These charge generation materials may be used alone or in combination of two or more.
In the charge generation layer (35), the charge generation material is dispersed in a suitable solvent together with a binder resin if necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is applied onto the conductive support. And formed by drying.
[0036]
The binder resin used for the charge generation layer (35) as necessary may be 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, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone Etc. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material. The binder resin may be added before or after dispersion.
[0037]
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. In particular, ketone solvents, ester solvents, and ether solvents are preferably used. These may be used alone or in combination of two or more.
[0038]
The charge generation layer (35) mainly comprises a charge generation material, a solvent, and a binder resin, and may contain a sensitizer, a dispersant, a surfactant, silicone oil, and the like. .
As a coating method of the coating solution, methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used.
The film thickness of the charge generation layer (35) is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.
[0039]
The charge transport layer (37) can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. If necessary, one or more plasticizers, leveling agents and the like can be added.
[0040]
Charge transport materials include hole transport materials and electron transport materials.
Examples of the electron transporting material include chloroanil, bromoanil, 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-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
[0041]
Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. Other known materials may be used. These charge transport materials may be used alone or in combination of two or more.
[0042]
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, 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, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
[0043]
The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably 25 μm or less from the viewpoint of resolution and responsiveness. The lower limit varies depending on the system to be used (particularly charging potential), but is preferably 5 μm or more.
[0044]
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. These may be used alone or in combination of two or more.
[0045]
When the photosensitive layer has the laminated structure as described above, it is more preferable that the organic sulfur compound to be contained in the photosensitive layer is contained in the charge transport layer.
[0046]
Next, the case where the photosensitive layer has a single layer structure will be described.
For the single photosensitive layer, all of the above-described charge generation materials, charge transport materials, binder resins and the like can be used.
The photosensitive layer can be formed by dissolving or dispersing a charge generating substance and a charge transporting substance, the above-described sulfur compound, and a binder resin in a suitable solvent, and applying and drying them. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight. The photosensitive layer is formed by dip coating, spray coating, bead coating, a coating solution in which a charge generating material and a binder resin are dispersed together with a charge transporting material using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane. It can be formed by coating with a ring coat. The film thickness of the photosensitive layer is suitably about 5 to 25 μm.
[0047]
Next, the protective layer (39) will be described.
The protective layer (39) disperses the filler material together with the binder resin through an appropriate solvent, adds and dissolves a compound having both a hindered amine structure and a hindered phenol structure, and coats it on the photosensitive layer. It is formed by drying. In order to suppress deterioration of the photoreceptor from active gases such as ozone by repeated use over a long period of time by using a compound having both a hindered amine structure and a hindered phenol structure in the protective layer that is the outermost layer of the photoreceptor, It is possible to dramatically improve not only the wear resistance but also the image stability.
[0048]
The hindered amine structure here refers to a structure in which a bulky atomic group exists in the vicinity of the amino nitrogen atom. So-called aromatic amines and aliphatic amine substances also fall under this category. The hindered phenol structure is a structure in which a bulky atomic group exists at the ortho position of the phenolic hydroxyl group. Although the details of the mechanism of action of the compounds having both of these structures have not been clarified, the steric hindrance caused by the presence of bulky atomic groups suppresses the thermal vibration of amino nitrogen atoms and phenolic hydroxyl groups, and externally. It is estimated to suppress the influence of the active gas.
[0049]
There are various examples of compounds having both a hindered amine structure and a hindered phenol structure, and all of them can be used. Among them, 1- [2- [3- represented by the following structural formula (II) can be used. (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2 , 6,6-tetramethylpyridine is preferred.
[0050]
Embedded image

[0051]
The ratio of the filler material and the compound having both the hindered amine structure and the hindered phenol structure is 0.01 wt% to 50 wt%, more preferably 0.1 wt% to 20 wt% with respect to the filler. If it is increased more than necessary, the wear resistance may be lowered. If the amount added is too small, the effect of suppressing abnormal images will not be sufficiently exhibited.
[0052]
The binder resin material used for the protective layer (39) includes ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, aryl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate. , Polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, polyarylate, AS resin, butadiene-styrene Resins such as polymers, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resins can be used. From the viewpoint of filler dispersibility, residual potential, and coating film defects, polycarbonate or polyarylate is particularly effective and useful.
[0053]
The filler used in the present invention is generally classified into an organic filler and an inorganic filler. Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like, and inorganic filler materials include copper, tin, aluminum, indium, and the like. Metal powders such as silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide, tin-doped indium oxide And metal fluorides such as tin fluoride, calcium fluoride and aluminum fluoride, potassium titanate, boron nitride and the like. Among these fillers, the use of an inorganic pigment which is an inorganic filler is advantageous for improving the wear resistance from the viewpoint of the hardness of the filler.
[0054]
Further, these fillers can be surface-treated with at least one kind of surface treatment agent, which is preferable from the viewpoint of the dispersibility of the filler. Lowering the dispersibility of the filler not only increases the residual potential, but also lowers the transparency of the coating, causes defects in the coating, and lowers the wear resistance. It can develop into a big problem. As the surface treatment agent, all conventionally used surface treatment agents can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. For example, titanate coupling agents, aluminum coupling agents, zircoaluminate coupling agents, higher fatty acids, etc., or mixed treatment of these with silane coupling agents, Al ₂ O _Three TiO ₂ , ZrO ₂ , Silicone, aluminum stearate, etc., or a mixture thereof is more preferable from the viewpoint of filler dispersibility and image blur. The treatment with the silane coupling agent is strongly influenced by image blur, but the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The surface treatment amount varies depending on the average primary particle size of the filler used, but is preferably 3 to 30 wt%, more preferably 5 to 20 wt%. If the surface treatment amount is less than this, the filler dispersion effect cannot be obtained, and if it is too much, the residual potential is significantly increased.
[0055]
As the solvent to be used, all solvents used in the charge transport layer (37) such as tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, and acetone can be used. However, a solvent having a high viscosity is preferable at the time of dispersion, but a solvent having high volatility is preferable at the time of coating. When there is no solvent satisfying these conditions, it is possible to use a mixture of two or more solvents having respective physical properties, which may have a great effect on filler dispersibility and residual potential. .
[0056]
In addition, the addition of the charge transport material mentioned in the charge transport layer (37) to the protective layer is effective and useful for reducing the residual potential and improving the image quality. At this time, a charge transport material is added to the protective layer so that the ionization potential (Ip) of the charge transport material contained in the protective layer is equal to or smaller than the Ip of the charge transport material contained in the photosensitive layer. As a result, the charge injection property to the protective layer is improved, so that the residual potential can be further reduced. The ionization potential Ip can be measured using various methods such as a method for obtaining spectroscopically and a method for obtaining electrochemically.
[0057]
The filler material can be dispersed using a conventional method such as a ball mill, an attritor, a sand mill, or an ultrasonic wave. Among these, dispersion by a ball mill with less contamination of impurities from the outside is more preferable from the viewpoint of dispersibility. With respect to the material of the media used, all media such as zirconia, alumina, and agate that have been conventionally used can be used.
[0058]
Moreover, it is preferable from the point of the light transmittance of a protective layer, and the abrasion resistance that the average primary particle diameter of a filler is 0.01-0.5 micrometer. When the average primary particle size of the filler is 0.01 μm or less, it causes a decrease in wear resistance, a decrease in dispersibility, etc., and when it is 0.5 μm or more, the settling property of the filler is promoted or the toner fills. May occur.
[0059]
As a method for forming the protective layer, conventional methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, etc. can be used. More preferred. Furthermore, it is possible to form the protective layer by coating the required film thickness of the protective layer at one time, but it is more uniform to apply the filler two or more times to make the protective layer multilayer. It is more preferable from the viewpoint of sex. By doing so, a further effect can be obtained with respect to reduction of residual potential, improvement of resolution, and improvement of wear resistance. In addition, about 0.1-10 micrometers is suitable for the thickness of a protective layer.
[0060]
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support (31) and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment 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 moire and reduce residual potential.
[0061]
These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, 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 _Three Anodic oxidation, organic materials such as polyparaxylylene (parylene), and SiO ₂ , SnO ₂ TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can be used well. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0062]
DETAILED DESCRIPTION OF THE INVENTION
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 examples also belong to the category of the present invention.
In FIG. 4, the photoconductor (1) has a drum shape, but it may be a sheet or an endless belt. The charging charger (3), pre-transfer charger (7), transfer charger (10), separation charger (11), and pre-cleaning charger (13) include corotron, scorotron, solid state charger, and charging. A roller or the like is used, and all known means can be used.
As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.
[0063]
Further, light sources such as an image exposure unit (5) and a charge removal lamp (2) include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), and electroluminescence (EL). ) And other luminescent materials can be used. Various types of 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 to irradiate only light in a desired wavelength range.
[0064]
In addition to the steps shown in FIG. 4, the light source or the like is provided with a transfer step, a static elimination step, a cleaning step, or a pre-exposure step that uses light irradiation, so that the photosensitive member is irradiated with light.
[0065]
The toner developed on the photoconductor (1) by the developing unit (6) is transferred to the transfer paper (9), but not all is transferred and remains on the photoconductor (1). Toner is also produced. Such toner is removed from the photoreceptor by the fur brush (14) and the blade (15). 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.
[0066]
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. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.
[0067]
FIG. 5 shows another example of the electrophotographic process according to the present invention. The photosensitive member (21) is driven by driving rollers (22a) and (22b), and is charged by a charger (23), image exposure by a light source (24), development (not shown), and transfer using a charger (25). The pre-cleaning exposure with the light source (26), the cleaning with the brush (27), and the charge removal with the light source (28) are repeated. In FIG. 5, the photoconductor (21) (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.
[0068]
The above illustrated electrophotographic process is illustrative of an embodiment of the present invention, and of course other embodiments are possible. For example, in FIG. 5, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or image exposure and neutralization light irradiation may be performed from the support side.
On the other hand, the light irradiation process is illustrated as image exposure, pre-cleaning exposure, and static elimination exposure. In addition, a pre-transfer exposure, a pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.
[0069]
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general example is shown in FIG.
[0070]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not restrict | limited by an Example. All parts are parts by weight. The ionization potential (Ip) of the charge transport material was measured with a surface analyzer (manufactured by Riken Keiki Co., Ltd., AC-1).
(Example 1)
An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition are sequentially applied on an aluminum cylinder by dip coating and dried to obtain a 3.5 μm undercoat layer, 0. A 2 μm charge generation layer and a 26 μm charge transport layer were formed.
[0071]
<Undercoat layer coating solution>
400 parts of titanium dioxide powder
40 parts of melamine resin
60 parts alkyd resin
2-butanone 500 parts
[0072]
<Charge generation layer coating solution>
12 parts of bisazo pigment with the following structure
[0073]
Embedded image

Polyvinyl butyral 5 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0074]
<Charge transport layer coating solution>
10 parts of polycarbonate (Z Polyca, manufactured by Teijin Chemicals)
10 parts of charge transport material (Ip: 5.4 eV) having the following structural formula
[0075]
Embedded image

0.15 parts of an organic sulfur compound (Sumitomo Chemical Co., Ltd.) having the following structural formula
[0076]
Embedded image

Tetrahydrofuran 100 parts
Further, a protective layer coating solution having the following composition was formed on the charge transport layer by spray coating to form a protective layer having a thickness of about 1.5 μm. Thus, an electrophotographic photoreceptor of Example 1 was produced.
[0077]
<Protective layer coating solution>
3 parts of alumina (average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical)
The hindered amine structure of the following structural formula and
Compound having hindered phenol structure 0.24 parts
[0078]
Embedded image

4 parts of charge transport material (Ip: 5.4 eV) having the following structural formula
[0079]
Embedded image

Polycarbonate (Z Polyca, Teijin Chemicals) 5.5 parts
220 parts of tetrahydrofuran
80 parts of cyclohexanone
[0080]
(Example 2)
An electrophotographic photoreceptor of Example 2 was produced in the same manner as in Example 1 except that the organic sulfur compound in the charge transport layer coating solution was changed to the following organic sulfur compound in Example 1.
0.15 parts of an organic sulfur compound (Sumitomo Chemical Co., Ltd.) having the following structural formula
[0081]
Embedded image

[0082]
( Reference example 1 )
In Example 1, except that the organic sulfur compound of the charge transport layer coating solution was changed to the following organic sulfur compound, all were the same as in Example 1, Reference example 1 An electrophotographic photoreceptor was prepared.
0.15 parts of an organic sulfur compound (Sumitomo Chemical Co., Ltd.) having the following structural formula
[0083]
Embedded image

[0084]
( Reference example 2 )
In Example 1, except that the compound having a hindered amine structure and a hindered phenol structure in the protective layer coating solution was changed to a compound having a hindered amine structure and a hindered phenol structure of the following structural formula, all were the same as in Example 1. , Reference example 2 An electrophotographic photoreceptor was prepared.
A compound having a hindered amine structure and a hindered phenol structure of the following structural formula
0.22 parts
[0085]
Embedded image

[0086]
(Example 3 )
Example 1 Example 1 was carried out in the same manner as Example 1 except that the filler contained in the protective layer was changed to the following material. 3 An electrophotographic photoreceptor was prepared.
Titanium oxide (average primary particle size 0.3μm, manufactured by Ishihara Sangyo) 3 parts
[0087]
(Example 4 )
Example 1 Example 1 was carried out in the same manner as Example 1 except that the filler contained in the protective layer was changed to the following material. 4 An electrophotographic photoreceptor was prepared.
Alumina (average primary particle size 0.6μm, manufactured by Ishihara Sangyo) 3 parts
[0088]
(Example 5 )
In Example 1, except that the filler contained in the protective layer was changed to the following materials, Example 1 was performed in the same manner as in Example 1. 5 An electrophotographic photoreceptor was prepared.
Silica (average particle size 0.015μm, Shin-Etsu Silicone) 2 parts
[0089]
(Example 6 )
In Example 1, except that the charge transport material contained in the protective layer was changed to the following materials, the same procedure as in Example 1 was carried out. 6 An electrophotographic photoreceptor was prepared.
10 parts of charge transport material (Ip: 5.3 eV) having the following structural formula
[0090]
Embedded image

[0091]
(Example 7 )
In Example 1, except that the charge transport material contained in the protective layer was changed to the following materials, the same procedure as in Example 1 was carried out. 7 An electrophotographic photoreceptor was prepared.
10 parts of charge transport material (Ip: 5.5 eV) having the following structural formula
[0092]
Embedded image

[0093]
(Example 8 )
In Example 1, except that the binder resin contained in the protective layer was changed to the following materials, the same procedure as in Example 1 was carried out. 8 An electrophotographic photoreceptor was prepared.
10 parts of polyarylate resin (U polymer, manufactured by Unitika)
[0094]
(Example 9 )
In Example 1, except that the charge generation layer coating solution, the charge transport layer coating solution and the protective layer coating solution were changed to the following ones, Example 1 9 An electrophotographic photoreceptor was prepared.
[0095]
<Charge generation layer coating solution>
9 parts of Y-type titanyl phthalocyanine
Polyvinyl butyral 5 parts
2-butanone 450 parts
[0096]
<Charge transport layer coating solution>
10 parts of C type polycarbonate
8 parts of charge transport material (Ip: 5.3 eV) having the following structural formula
[0097]
Embedded image

0.15 parts of an organic sulfur compound (Sumitomo Chemical Co., Ltd.) having the following structural formula
[0098]
Embedded image

70 parts of toluene
[0099]
<Protective layer coating solution>
Alumina-treated titanium oxide
(Average primary particle size 0.035μm, manufactured by Teica) 3 parts
Methacrylic acid / methyl methacrylate copolymer
(Acid value 50 mgKOH / g) 0.5 part
C-type polycarbonate (manufactured by Teijin Chemicals) 5.5 parts
The hindered amine structure of the following structural formula and
Compound having hindered phenol structure 0.24 parts
[0100]
Embedded image

4 parts of charge transport material (Ip: 5.3 eV) having the following structural formula
[0101]
Embedded image

250 parts of tetrahydrofuran
50 parts of cyclohexanone
[0102]
(Comparative Example 1)
In Example 1, an electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the protective layer was not provided.
[0103]
(Comparative Example 2)
In Example 1, an electrophotographic photosensitive member of Comparative Example 2 was produced in the same manner as in Example 1 except that alumina was not added to the protective layer coating solution.
[0104]
(Comparative Example 3)
In Example 1, all were carried out in the same manner as in Example 1 except that the compound having a hindered amine structure and a hindered phenol structure was not added to the protective layer coating solution, and no organic sulfur compound was added to the charge transport layer coating solution. Then, an electrophotographic photoreceptor of Comparative Example 3 was produced.
[0105]
(Comparative Example 4)
In Example 1, an electrophotographic photosensitive member of Comparative Example 4 was produced in the same manner as in Example 1 except that the organic sulfur compound was not added to the charge transport layer coating solution.
[0106]
(Comparative Example 5)
An electrophotographic photoreceptor of Comparative Example 5 was produced in the same manner as in Example 1 except that the compound having a hindered amine structure and a hindered phenol structure was not added to the protective layer coating solution in Example 1.
[0107]
(Comparative Example 6)
In Example 1, except that the organic sulfur compound was not added to the charge transport layer coating solution, but the same amount of the compound represented by the following structural formula was added instead. An electrophotographic photosensitive member was produced.
[0108]
Embedded image

[0109]
(Comparative Example 7)
In Example 1, except that the organic sulfur compound was not added to the charge transport layer coating solution, but the same amount of the compound represented by the following structural formula was added instead. An electrophotographic photosensitive member was produced.
[0110]
Embedded image

[0111]
(Comparative Example 8)
In Example 1, all were carried out in the same manner as in Example 1 except that the compound having the hindered amine structure and the hindered phenol structure was not added to the protective layer coating solution, but instead the same amount of the compound represented by the following structural formula was added. An electrophotographic photosensitive member of Comparative Example 8 was produced.
[0112]
Embedded image

[0113]
(Comparative Example 9)
In Example 1, all were carried out in the same manner as in Example 1 except that the compound having the hindered amine structure and the hindered phenol structure was not added to the protective layer coating solution, but instead the same amount of the compound represented by the following structural formula was added. An electrophotographic photosensitive member of Comparative Example 9 was produced.
[0114]
Embedded image

[0115]
(Comparative Example 10)
In Example 1, all were carried out except that the organic sulfur compound was not added to the charge transport layer coating solution, and instead the compound having a hindered amine structure and a hindered phenol structure used in the protective layer coating solution of Example 1 was added. In the same manner as in Example 1, an electrophotographic photoreceptor of Comparative Example 10 was produced.
[0116]
(Comparative Example 11)
In Example 1, all were performed except that the compound having a hindered amine structure and a hindered phenol structure was not added to the protective tank coating solution, and the organic sulfur compound used in the charge transport layer coating solution of Example 1 was added instead. In the same manner as in Example 1, an electrophotographic photoreceptor of Comparative Example 10 was produced.
[0117]
Examples 1 to 1 produced as described above 9, Reference Examples 1-2 Ricoh's laser printer using the electrophotographic photosensitive member of Comparative Example 1 to 11 and an electrophotographic photosensitive member of Comparative Examples 1 to 11 in an electrophotographic process cartridge (without exposure before cleaning), and using a 655 nm semiconductor laser as an image exposure light source First, 10,000 sheets were printed continuously with a modified machine, and at that time, the initial image and the dark portion potential, the bright portion potential, and the image quality after 10,000 sheet printing were evaluated. The dark part potential, the bright part potential, and the image quality were evaluated as follows.
Dark area potential: Photoreceptor surface potential when moved to the development position after primary charging
Bright area potential: After temporary charging, after exposure to the image (full exposure), the photoreceptor surface potential when moved to the development position
Image quality: Comprehensive evaluation of output image density, fine line reproducibility, blurred text, resolution, background stains, etc.
In addition, after printing 10,000 sheets, a gas exposure test was performed in which the photoconductor was left in an environment with ozone and NOx gas concentrations of 10 ppm for 10 days respectively. Evaluation was performed.
Furthermore, after printing up to 100,000 sheets, evaluation was made on dark part potential, bright part potential, and image quality. The film thickness was measured after 100,000 sheets were printed, and the amount of wear was evaluated from the difference in film thickness before and after printing.
If abnormal images were generated, the subsequent evaluation was stopped. The results are shown in Table 1.
[0118]
[Table 1]

From the evaluation results in Table 1, the photoreceptors of the examples show excellent electrostatic stability with little change in both dark part potential and bright part potential, excellent chemical stability against active gas, and high resistance. It can be seen that it has wear and can stably obtain a high-quality image.
[0119]
【The invention's effect】
As described above, as is clear from the detailed and specific description, the present invention does not generate an abnormal image such as a residual potential increase or image blur even after repeated use, and can stably obtain a high-quality image over a long period of time. Providing durable photoconductors, and using these photoconductors eliminates the need to replace photoconductors and realizes downsizing of the device accompanying high-speed printing or reducing the diameter of the photoconductor. In addition, the present invention provides an extremely excellent effect of providing an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge capable of stably obtaining high-quality images.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a cross section of an electrophotographic photosensitive member of the present invention.
FIG. 2 is another view schematically showing a cross section of the electrophotographic photosensitive member of the present invention.
FIG. 3 is still another view schematically showing a cross section of the electrophotographic photosensitive member of the present invention.
FIG. 4 is a schematic view of an electrophotographic apparatus and a process cartridge for an electrophotographic apparatus according to the present invention.
FIG. 5 is a schematic view of another electrophotographic apparatus of the present invention.
FIG. 6 is another view showing the process cartridge of the present invention.
[Explanation of symbols]
1 Photoconductor
2 Static elimination lamp
3 Charger charger
4 Eraser
5 Image exposure section
6 Development unit
7 Charger before transfer
8 Registration roller
9 Transfer paper
10 Transcription charger
11 Separate charger
12 Separating nails
13 Charger before cleaning
14 Fur brush
15 Cleaning brush
16 photoconductor
17 Charger charger
18 Cleaning brush
19 Image exposure unit
20 Development roller
21 photoconductor
22a Driving roller
22b Driving roller
23 Charger charger
24 Image exposure source
25 Transcription Charger
26 Exposure before cleaning
27 Cleaning brush
28 Static elimination light source
31 Conductive support
33 Photosensitive layer
35 Charge generation layer
37 Charge transport layer
39 Protective layer

Claims (4)

An electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer containing a filler are sequentially formed on a conductive support, wherein the photosensitive layer is mainly composed of a charge generating material and a charge transport material. And an electron- containing layer containing an organic sulfur-based compound in the charge-transporting layer and a compound having both a hindered amine structure and a hindered phenol structure in the protective layer. In the photographic photoreceptor, the organic sulfur compound contained in the photosensitive layer is a compound represented by the following general formula (I), and both structures of a hindered amine structure and a hindered phenol structure contained in the protective layer: The compound having the formula (II) is a compound represented by the following structural formula (II), and the filler contained in the protective layer is at least one inorganic pigment Electrophotographic photosensitive member, characterized.

(Where n represents a natural number and is a number from 8 to 25)

An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeated on an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the one according to claim 1. Photo method. An electrophotographic apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1. A feature of an electrophotographic apparatus. An electrophotographic apparatus process cartridge comprising at least an electrophotographic photoreceptor, wherein the electrophotographic photoreceptor is the one according to claim 1. .

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