JP3773868B2 - Electrophotographic photosensitive member, electrophotographic method using the same, electrophotographic apparatus, process cartridge for electrophotographic apparatus - Google Patents

Description

式中、Ｃｐ_１、Ｃｐ_２はカップラー残基を表し、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し、同一でも異なっていても良い。またＣｐ_１、Ｃｐ_２は下記（ＩＩ）式で表され、
【００８２】
【化２】

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す。
【００８３】
特に、前記Ｃｐ１とＣｐ２が異なる構造の非対称アゾ顔料は、Ｃｐ１とＣｐ２が同一構造である対象型のアゾ顔料よりも、光感度が良好な場合が多く、感光体の小径化、使用プロセスの高速化に対応できるものであり、有効に使用される。
【００８４】
また、ブラッグ角２θの回折ピーク（±０．２゜）として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の中でも、最低角として７．３゜にピークを有するチタニルフタロシアニン（特開２００１−１９８７１号公報に記載）が、高感度であり、繰り返し使用における帯電性の低下が小さく、特に有効に使用できる。
【００８５】
電荷発生層３５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。
【００８６】
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。
【００８７】
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。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。
【００８８】
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。
【００８９】
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。
【００９０】
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。
【００９１】
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。
【００９２】
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）に異なるが、５μｍ以上が好ましい。
【００９３】
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、アセトンなどがあげられる。
【００９４】
本発明の感光体において電荷輸送層３７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。
【００９５】
次に感光層が単層構成３３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。
【００９６】
結着樹脂としては、先に電荷輸送層３７で挙げた結着樹脂をそのまま用いるほかに、電荷発生層３５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。
【００９７】
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。
【００９８】
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。
【００９９】
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。
【０１００】
本発明の感光体においては、感光層保護の目的で、表面層３９が感光層の上に設けられる。表面層３９は、フィラー濃度が支持体側から表面側に向かい、連続的に高くなるように構成される（図１、図２）。あるいは、表面層３９は、フィラー濃度が異なる複数の層より構成され（図３、図４）、この場合、フィラー濃度が支持体側から表面側に向かい、順次高くなるように構成される。これにより、表面の耐摩耗性向上と残留電位低減の両立を図ることが可能になる。
【０１０１】
表面層中のフィラー濃度は使用するフィラー種により、また感光体を使用する電子写真プロセス条件によっても異なるが、最表層側又は最表層側の層においては、全固形分に対するフィラーの比で４０重量％以下、好ましくは３０重量％以下、５重量％以上、好ましくは１０重量％以上程度が良好である。最感光層側の層においては３０重量％以下、好ましくは１０重量％以下程度が良好である。表面層の最表面のフィラー濃度が５重量％以下であると耐摩耗性が得られず、また、繰り返し使用による摩耗による膜厚のバラツキが大きくなる。一方、４０重量％以上であると、繰り返し使用による残留電位の上昇が大きくなったり、表面性が荒れたり、書き込み光の散乱が大きくなったりする。
【０１０２】
表面層３９に使用される材料としては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、ポリアリレート、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、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。中でも、ポリカーボネートもしくはポリアリレートが最も良好に使用できる。
【０１０３】
また、感光体の表面層にはその他、耐摩耗性を向上する目的でフィラー材料が添加される。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、シリコーン樹脂粉末、ａ−カー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、酸化インジウム、酸化アンチモン、酸化ビスマス、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、チタン酸カリウムなどの無機材料が挙げられる。特に、フィラーの硬度の点からは、この中でも無機材料を用いることが有利である。特に、シリカ、酸化チタン、アルミナが有効に使用できる。
【０１０４】
更に、画像ボケが発生しにくいフィラーとしては、電気絶縁性が高いフィラー（比抵抗が１０^１０Ω・ｃｍ以上）が好ましく、フィラーのｐＨが５以上を示すものやフィラーの誘電率が５以上を示すものが特に有効に使用できる。また、ｐＨが５以上のフィラーあるいは誘電率が５以上のフィラーを単独で使用することはもちろん、ｐＨが５以下のフィラーとｐＨが５以上のフィラーとを２種類以上を混合したり、誘電率が５以下のフィラーと誘電率が５以上のフィラーとを２種類以上混合したりして用いることも可能である。また、これらのフィラーの中でも高い絶縁性を有し、熱安定性が高い上に、耐摩耗性が高い六方細密構造であるα型アルミナは、画像ボケの抑制や耐摩耗性の向上の点から特に有用である。
【０１０５】
本発明において使用するフィラーの比抵抗は以下のように定義される。フィラーのような粉体は、充填率によりその比抵抗値が異なるので、一定の条件下で測定する必要がある。本発明においては、特開平５−９４０４９号公報（図１）、特開平５−１１３６８８号公報（図１）に示された測定装置と同様の構成の装置を用いて、フィラーの比抵抗値を測定し、この値を用いた。測定装置において、電極面積は４．０ｃｍ^２である。測定前に片側の電極に４ｋｇの荷重を１分間かけ、電極間距離が４ｍｍになるように試料量を調節する。測定の際は、上部電極の重量（１ｋｇ）の荷重状態で測定を行い、印加電圧は１００Ｖにて測定する。１０^６Ω・ｃｍ以上の領域は、ＨＩＧＨ ＲＥＳＩＳＴＡＮＣＥ ＭＥＴＥＲ（横河ヒューレットパッカード）、それ以下の領域についてはデジタルマルチメーター（フルーク）により測定した。これにより得られた比抵抗値を本発明の言うところの比抵抗値と定義するものである。
【０１０６】
また、本発明の構成要件の一つであるフィラーのｐＨも解像度やフィラーの分散性に大きく影響する。その理由の一つとしては、フィラー、特に金属酸化物は製造時に塩酸等が残存することが考えられる。その残存量が多い場合には、画像ボケの発生は避けられず、またそれは残存量によってはフィラーの分散性にも影響を及ぼす場合がある。もう一つの理由としては、フィラー、特に金属酸化物の表面における帯電性の違いによるものである。通常、液体中に分散している粒子はプラスあるいはマイナスに帯電しており、それを電気的に中性に保とうとして反対の電荷を持つイオンが集まり、そこで電気二重層が形成されることによって粒子の分散状態は安定化している。粒子から遠ざかるに従いその電位（ゼータ電位）は徐々に低くなり、粒子から十分に離れて電気的に中性である領域の電位はゼロとなる。従って、ゼータ電位の絶対値の増加によって粒子の反発力が高くなることによって安定性は高くなり、ゼロに近づくに従い凝集しやすく不安定になる。一方、系のｐＨ値によってゼータ電位は大きく変動し、あるｐＨ値において電位はゼロとなり等電点を持つことになる。従って、系の等電点からできるだけ遠ざけて、ゼータ電位の絶対値を高めることによって分散系の安定化が図られることになる。
【０１０７】
本発明の構成においては、フィラーとしては前述の等電点におけるｐＨが、少なくとも５以上を示すものが画像ボケ抑制の点から好ましく、より塩基性を示すフィラーであるほどその効果が高くなる傾向があることが確認された。等電点におけるｐＨが高い塩基性を示すフィラーは、系が酸性であった方がゼータ電位はより高くなることにより、分散性及びその安定性は向上することになる。ここで、本発明におけるフィラーのｐＨは、ゼータ電位から等電点におけるｐＨ値を記載した。この際、ゼータ電位の測定は、大塚電子（株）製レーザーゼータ電位計にて測定した。フィラーの誘電率は以下のように測定した。上述のような比抵抗の測定と同様なセルを用い、荷重をかけた後に、静電容量を測定し、これより誘電率を求めた。静電容量の測定は、誘電体損測定器（安藤電気（株）製）を使用した。
【０１０８】
更に、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、Ａｌ_２Ｏ_３、ＴｉＯ_２、ＺｒＯ_２、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。
【０１０９】
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。これらフィラー材料は単独もしくは２種類以上混合して用いられる。フィラーの表面処理量に関しては、上述のようにフィラー量に対する使用する表面処理剤の重量比で定義される。
【０１１０】
これらフィラー材料は、適当な分散機を用いることにより分散できる。また、フィラーの平均粒径は、１μｍ以下、好ましくは０．５μｍ以下にあること表面層の透過率の点から好ましい。尚、本発明におけるフィラーの平均粒径とは、特別な記載のない限り体積平均粒径であり、超遠心式自動粒度分布測定装置：ＣＡＰＡ−７００（堀場製作所製）により求めたものである。この際、累積分布の５０％に相当する粒子径（Ｍｅｄｉａｎ系）として算出されたものである。また、同時に測定される各々の粒子の標準偏差が１μｍ以下であることが重要である。これ以上の標準偏差の値である場合には、粒度分布が広すぎて、本発明の効果が顕著に得られなくなってしまう場合がある。
【０１１１】
なお、表面層の厚さは複数層の合計で０．１〜１０μｍ程度が適当である。
【０１１２】
本発明の表面層の形成法としては通常の塗布法が採用される。中でも、スプレー工法は有効な手段である。複数のフィラー濃度の異なる表面層用塗工液を、下層が指触乾燥する前に順次スプレー法で積層していく方法、あるいは下層の指触乾燥が終了したら順次スプレー法で積層していく方法が、最も適している。この場合、塗工液の数だけスプレーヘッドを用意し、塗工を連続的に行うことが望ましい。
【０１１３】
また、表面層３９には残留電位低減、応答性改良のため、電荷輸送物質を含有しても良い。電荷輸送物質は、電荷輸送層の説明のところに記載した材料を用いることができる。電荷輸送物質として、低分子電荷輸送物質を用いる場合には、複数の表面層中における濃度を変えても構わない。耐摩耗性向上のため、表面側を低濃度にすることは有効な手段である。ここで言う濃度とは、表面層を構成する全材料の総重量に対する低分子電荷輸送物質の重量の比を表し、濃度傾斜とは上記重量比において表面側において濃度が低くなるような傾斜を設けることを示す。
【０１１４】
また、表面層に使用する電荷輸送物質は、上述のように低分子電荷輸送物質でも、後述のような高分子電荷輸送物質でも良いが、表面層の下層として形成される感光層あるいは電荷輸送層に用いられる電荷輸送物質と同一のものを用いることが好ましい。これは、感光層で形成された光キャリアが感光体表面に輸送される際、感光層（電荷輸送層）から表面層に電荷が渡されるが、同一構造の場合にはエネルギーギャップ（障壁）等を形成することなく、スムーズな電荷の受け渡しが行われるためである。
【０１１５】
また、表面層には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。これら高分子電荷輸送物質から構成される表面層は耐摩耗性に優れたものである。高分子電荷輸送物質としては、公知の材料が使用できるが、特に、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が良好に用いられる。中でも、（ＩＩＩ）〜（ＸＩＩ）式で表される高分子電荷輸送物質が良好に用いられ、これらを以下に例示し、具体例を示す。
【０１１６】
（ＩＩＩ）式
【０１１７】
【化３】

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、Ｒ４は水素原子又は置換もしくは無置換のアルキル基、Ｒ_５、Ｒ６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は組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表し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される２価基を表す。
【０１１８】
【化４】

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価基を表す。）または、
【０１１９】
【化５】

（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す。）を表す。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。
【０１２０】
（ＩＶ）式
【０１２１】
【化６】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１２２】
（Ｖ）式
【０１２３】
【化７】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１２４】
（ＶＩ）式
【０１２５】
【化８】

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の整数を表す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１２６】
（ＶＩＩ）式
【０１２７】
【化９】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１２８】
（ＶＩＩＩ）式
【０１２９】
【化１０】

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、ビニレン基を表し同一であっても異なってもよい。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１３０】
（ＩＸ）式
【０１３１】
【化１１】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１３２】
（Ｘ）式
【０１３３】
【化１２】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１３４】
（ＸＩ）式
【０１３５】
【化１３】

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_２５、Ａｒ_２７、Ａｒ_２８は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１３６】
（ＸＩＩ）式
【０１３７】
【化１４】

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す。Ｘ、ｋ、ｊおよびｎは、（ＩＩＩ）式の場合と同じである。
【０１３８】
また、保護層に使用される高分子電荷輸送物質として、上述の高分子電荷輸送物質の他に、保護層の成膜時には電子供与性基を有するモノマーあるいはオリゴマーの状態で、成膜後に硬化反応あるいは架橋反応をさせることで、最終的に２次元あるいは３次元の架橋構造を有する重合体も含むものである。
【０１３９】
これら電子供与性基を有する重合体から構成される保護層、あるいは架橋構造を有する重合体は耐摩耗性に優れたものである。通常、電子写真プロセスにおいては、帯電電位（未露光部電位）は一定であるため、繰り返し使用により感光体の表面層が摩耗すると、その分だけ感光体にかかる電界強度が高くなってしまう。この電界強度の上昇に伴い、地汚れの発生頻度が高くなるため、感光体の耐摩耗性が高いことは、地汚れに対して有利である。これら電子供与性基を有する重合体から構成される保護層は、自身が高分子化合物であるため成膜性に優れ、低分子分散型高分子からなる保護層に比べ、電荷輸送部位を高密度に構成することが可能で電荷輸送能に優れたものである。このため、高分子電荷輸送物質を用いた保護層を有する感光体には高速応答性が期待できる。
【０１４０】
その他の電子供与性基を有する重合体としては、公知単量体の共重合体や、ブロック重合体、グラフト重合体、スターポリマーや、また、例えば特開平３−１０９４０６号公報、特開２００００−２０６７２３号公報、特開２００１−３４００１号公報等に開示されているような電子供与性基を有する架橋重合体などを用いることも可能である。
【０１４１】
本発明の感光体においては感光層と保護層との間に中間層を設けることも可能である中間層には、一般にバインダー樹脂を主成分として用いる。これら樹脂としては、ポリアミド、アルコール可溶性ナイロン、水溶性ポリビニルブチラール、ポリビニルブチラール、ポリビニルアルコールなどが挙げられる。中間層の形成法としては、前述のごとく通常の塗布法が採用される。なお、中間層の厚さは０．０５〜２μｍ程度が適当である。
【０１４２】
また、本発明においては、耐環境性の改善のため、とりわけ、感度低下、残留電位の上昇を防止する目的で、各層に酸化防止剤、可塑剤、滑剤、紫外線吸収剤、低分子電荷輸送物質およびレベリング剤を添加することができる。これらの化合物の代表的な材料を以下に記す。
【０１４３】
各層に添加できる酸化防止剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
【０１４４】
（ａ）フェノ−ル系化合物
２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ブチル化ヒドロキシアニソ−ル、２，６−ジ−ｔ−ブチル−４−エチルフェノ−ル、ｎ−オクタデシル−３−（４’−ヒドロキシ−３’，５’−ジ−ｔ−ブチルフェノール）、２，２’−メチレン−ビス−（４−メチル−６−ｔ−ブチルフェノ−ル）、２，２’−メチレン−ビス−（４−エチル−６−ｔ−ブチルフェノ−ル）、４，４’−チオビス−（３−メチル−６−ｔ−ブチルフェノ−ル）、４，４’−ブチリデンビス−（３−メチル−６−ｔ−ブチルフェノ−ル）、１，１，３−トリス−（２−メチル−４−ヒドロキシ−５−ｔ−ブチルフェニル）ブタン、１，３，５−トリメチル−２，４，６−トリス（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）ベンゼン、テトラキス−［メチレン−３−（３’，５’−ジ−ｔ−ブチル−４’−ヒドロキシフェニル）プロピオネ−ト］メタン、ビス［３，３’−ビス（４’−ヒドロキシ−３’−ｔ−ブチルフェニル）ブチリックアッシド］クリコ−ルエステル、トコフェロ−ル類など。
【０１４５】
（ｂ）パラフェニレンジアミン類
Ｎ−フェニル−Ｎ’−イソプロピル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジ−ｓｅｃ−ブチル−ｐ−フェニレンジアミン、Ｎ−フェニル−Ｎ−ｓｅｃ−ブチル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジ−イソプロピル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジメチル−Ｎ，Ｎ’−ジ−ｔ−ブチル−ｐ−フェニレンジアミンなど。
【０１４６】
（ｃ）ハイドロキノン類
２，５−ジ−ｔ−オクチルハイドロキノン、２，６−ジドデシルハイドロキノン、２−ドデシルハイドロキノン、２−ドデシル−５−クロロハイドロキノン、２−ｔ−オクチル−５−メチルハイドロキノン、２−（２−オクタデセニル）−５−メチルハイドロキノンなど。
【０１４７】
（ｄ）有機硫黄化合物類
ジラウリル−３，３’−チオジプロピオネ−ト、ジステアリル−３，３’−チオジプロピオネ−ト、ジテトラデシル−３，３’−チオジプロピオネ−トなど。
【０１４８】
（ｅ）有機燐化合物類
トリフェニルホスフィン、トリ（ノニルフェニル）ホスフィン、トリ（ジノニルフェニル）ホスフィン、トリクレジルホスフィン、トリ（２，４−ジブチルフェノキシ）ホスフィンなど。
【０１４９】
各層に添加できる可塑剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
【０１５０】
（ａ）リン酸エステル系可塑剤
リン酸トリフェニル、リン酸トリクレジル、リン酸トリオクチル、リン酸オクチルジフェニル、リン酸トリクロルエチル、リン酸クレジルジフェニル、リン酸トリブチル、リン酸トリ−２−エチルヘキシル、リン酸トリフェニルなど。
【０１５１】
（ｂ）フタル酸エステル系可塑剤
フタル酸ジメチル、フタル酸ジエチル、フタル酸ジイソブチル、フタル酸ジブチル、フタル酸ジヘプチル、フタル酸ジ−２−エチルヘキシル、フタル酸ジイソオクチル、フタル酸ジ−ｎ−オクチル、フタル酸ジノニル、フタル酸ジイソノニル、フタル酸ジイソデシル、フタル酸ジウンデシル、フタル酸ジトリデシル、フタル酸ジシクロヘキシル、フタル酸ブチルベンジル、フタル酸ブチルラウリル、フタル酸メチルオレイル、フタル酸オクチルデシル、フマル酸ジブチル、フマル酸ジオクチルなど。
【０１５２】
（ｃ）芳香族カルボン酸エステル系可塑剤
トリメリット酸トリオクチル、トリメリット酸トリ−ｎ−オクチル、オキシ安息香酸オクチルなど。
【０１５３】
（ｄ）脂肪族二塩基酸エステル系可塑剤
アジピン酸ジブチル、アジピン酸ジ−ｎ−ヘキシル、アジピン酸ジ−２−エチルヘキシル、アジピン酸ジ−ｎ−オクチル、アジピン酸−ｎ−オクチル−ｎ−デシル、アジピン酸ジイソデシル、アジピン酸ジカプリル、アゼライン酸ジ−２−エチルヘキシル、セバシン酸ジメチル、セバシン酸ジエチル、セバシン酸ジブチル、セバシン酸ジ−ｎ−オクチル、セバシン酸ジ−２−エチルヘキシル、セバシン酸ジ−２−エトキシエチル、コハク酸ジオクチル、コハク酸ジイソデシル、テトラヒドロフタル酸ジオクチル、テトラヒドロフタル酸ジ−ｎ−オクチルなど。
【０１５４】
（ｅ）脂肪酸エステル誘導体
オレイン酸ブチル、グリセリンモノオレイン酸エステル、アセチルリシノール酸メチル、ペンタエリスリトールエステル、ジペンタエリスリトールヘキサエステル、トリアセチン、トリブチリンなど。
【０１５５】
（ｆ）オキシ酸エステル系可塑剤
アセチルリシノール酸メチル、アセチルリシノール酸ブチル、ブチルフタリルブチルグリコレート、アセチルクエン酸トリブチルなど。
【０１５６】
（ｇ）エポキシ系可塑剤
エポキシ化大豆油、エポキシ化アマニ油、エポキシステアリン酸ブチル、エポキシステアリン酸デシル、エポキシステアリン酸オクチル、エポキシステアリン酸ベンジル、エポキシヘキサヒドロフタル酸ジオクチル、エポキシヘキサヒドロフタル酸ジデシルなど。
【０１５７】
（ｈ）二価アルコールエステル系可塑剤
ジエチレングリコールジベンゾエート、トリエチレングリコールジ−２−エチルブチラートなど。
【０１５８】
（ｉ）含塩素系可塑剤
塩素化パラフィン、塩素化ジフェニル、塩素化脂肪酸メチル、メトキシ塩素化脂肪酸メチルなど。
【０１５９】
（ｊ）ポリエステル系可塑剤
ポリプロピレンアジペート、ポリプロピレンセバケート、ポリエステル、アセチル化ポリエステルなど。
【０１６０】
（ｋ）スルホン酸誘導体
ｐ−トルエンスルホンアミド、ｏ−トルエンスルホンアミド、ｐ−トルエンスルホンエチルアミド、ｏ−トルエンスルホンエチルアミド、トルエンスルホン−Ｎ−エチルアミド、ｐ−トルエンスルホン−Ｎ−シクロヘキシルアミドなど。
【０１６１】
（ｌ）クエン酸誘導体
クエン酸トリエチル、アセチルクエン酸トリエチル、クエン酸トリブチル、アセチルクエン酸トリブチル、アセチルクエン酸トリ−２−エチルヘキシル、アセチルクエン酸−ｎ−オクチルデシルなど。
【０１６２】
（ｍ）その他
ターフェニル、部分水添ターフェニル、ショウノウ、２−ニトロジフェニル、ジノニルナフタリン、アビエチン酸メチルなど。
【０１６３】
各層に添加できる滑剤としては、例えば下記のものが挙げられるがこれらに限定されるものではない。
【０１６４】
（ａ）炭化水素系化合物
流動パラフィン、パラフィンワックス、マイクロワックス、低重合ポリエチレンなど。
【０１６５】
（ｂ）脂肪酸系化合物
ラウリン酸、ミリスチン酸、パルチミン酸、ステアリン酸、アラキジン酸、ベヘン酸など。
【０１６６】
（ｃ）脂肪酸アミド系化合物
ステアリルアミド、パルミチルアミド、オレインアミド、メチレンビスステアロアミド、エチレンビスステアロアミドなど。
【０１６７】
（ｄ）エステル系化合物
脂肪酸の低級アルコールエステル、脂肪酸の多価アルコールエステル、脂肪酸ポリグリコールエステルなど。
【０１６８】
（ｅ）アルコール系化合物
セチルアルコール、ステアリルアルコール、エチレングリコール、ポリエチレングリコール、ポリグリセロールなど。
【０１６９】
（ｆ）金属石けん
ステアリン酸鉛、ステアリン酸カドミウム、ステアリン酸バリウム、ステアリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムなど。
【０１７０】
（ｇ）天然ワックス
カルナバロウ、カンデリラロウ、蜜ロウ、鯨ロウ、イボタロウ、モンタンロウなど。
【０１７１】
（ｈ）その他
シリコーン化合物、フッ素化合物など。
【０１７２】
各層に添加できる紫外線吸収剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
【０１７３】
（ａ）ベンゾフェノン系
２−ヒドロキシベンゾフェノン、２，４−ジヒドロキシベンゾフェノン、２，２’，４−トリヒドロキシベンゾフェノン、２，２’，４，４’−テトラヒドロキシベンゾフェノン、２，２’−ジヒドロキシ４−メトキシベンゾフェノンなど。
【０１７４】
（ｂ）サルシレート系
フェニルサルシレート、２，４ジ−ｔ−ブチルフェニル３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾエートなど。
【０１７５】
（ｃ）ベンゾトリアゾール系
（２’−ヒドロキシフェニル）ベンゾトリアゾール、（２’−ヒドロキシ５’−メチルフェニル）ベンゾトリアゾール、（２’−ヒドロキシ５’−メチルフェニル）ベンゾトリアゾール、（２’−ヒドロキシ３’−ターシャリブチル５’−メチルフェニル）５−クロロベンゾトリアゾール
【０１７６】
（ｄ）シアノアクリレート系
エチル−２−シアノ−３，３−ジフェニルアクリレート、メチル２−カルボメトキシ３（パラメトキシ）アクリレートなど。
【０１７７】
（ｅ）クエンチャー（金属錯塩系）
ニッケル（２，２’チオビス（４−ｔ−オクチル）フェノレート）ノルマルブチルアミン、ニッケルジブチルジチオカルバメート、ニッケルジブチルジチオカルバメート、コバルトジシクロヘキシルジチオホスフェートなど。
【０１７８】
（ｆ）ＨＡＬＳ （ヒンダードアミン）
ビス（２，２，６，６−テトラメチル−４−ピペリジル）セバケート、ビス（１，２，２，６，６−ペンタメチル−４−ピペリジル）セバケート、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、８−ベンジル−７，７，９，９−テトラメチル−３−オクチル−１，３，８−トリアザスピロ〔４，５〕ウンデカン−２，４−ジオン、４−ベンゾイルオキシ−２，２，６，６−テトラメチルピペリジンなど。
【０１７９】
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５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５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フィラー濃度傾斜をもつ表面層又はフィラー濃度の異なる複数層より構成された表面層とが設けられてなる。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。帯電部材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）、帯電ローラーを始めとする公知の手段が用いられる。帯電部材３は、感光体１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。
【０１８０】
ここでいう接触方式の帯電部材とは、感光体表面に帯電部材の表面が接触するタイプのものであり、帯電ローラー、帯電ブレード、帯電ブラシの形状がある。中でも帯電ローラーや帯電ブラシが良好に使用される。また、近接配置した帯電部材とは、感光体表面と帯電部材表面の間に２００μｍ以下の空隙（ギャップ）を有するように非接触状態で近接配置したタイプのものである。空隙の距離から、コロトロン、スコロトロンに代表される公知の帯電器とは区別されるものである。本発明において使用される近接配置された帯電部材は、感光体表面との空隙を適切に制御できる機構のものであればいかなる形状のものでも良い。例えば、感光体の回転軸と帯電部材の回転軸を機械的に固定して、適正ギャップを有するような配置にすればよい。中でも、帯電ローラーの形状の帯電部材を用い、帯電部材の非画像形成部両端にギャップ形成部材を配置して、この部分のみを感光体表面に当接させ、画像形成領域を非接触配置させる、あるいは感光体非画像形成部両端ギャップ形成部材を配置して、この部分のみを帯電部材表面に当接させ、画像形成領域を非接触配置させる様な方法が、簡便な方法でギャップを安定して維持できる方法である。特に特願平１３−２１１４４８号、特願平１３−２２６４３２号に記載された方法は良好に使用できる。帯電部材側にギャップ形成部材を配置した近接帯電機構の一例を図９に示す。
【０１８１】
また、帯電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。
【０１８２】
転写手段には、一般に上記の帯電器が使用できるが、図５に示されるように転写チャージャー１０と分離チャージャー１１を併用したものが効果的である。
【０１８３】
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。かかる光源等は、図５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。
【０１８４】
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。
【０１８５】
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。
【０１８６】
図６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フィラー濃度傾斜をもつ表面層又はフィラー濃度の異なる複数層より構成された表面層とが設けられてなる。駆動ローラー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６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。
【０１８７】
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６において支持体側よりクリーニング前露光を行っているが、これは表面層側から行ってもよいし、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。
【０１８８】
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７に示すものが挙げられる。感光体２３は、導電性支持体上に、少なくとも感光層とフィラー濃度傾斜をもつ表面層又はフィラー濃度の異なる複数層より構成される表面層が設けられてなる。
【０１８９】
図１０は、本発明のタンデム方式のフルカラー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１０において、符号１Ｃ、１Ｍ、１Ｙ、１Ｋはドラム状の感光体であり、この感光体１Ｃ、１Ｍ、１Ｙ、１Ｋは図中の矢印方向に回転し、その周りに少なくとも回転順に帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋ、現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋ、クリーニング部材５Ｃ、５Ｍ、５Ｙ、５Ｋが配置されている。帯電部材 ２Ｃ、２Ｍ、２Ｙ、２Ｋは、感光体表面を均一に帯電するための帯電装置を構成する帯電部材である。この帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋと現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋの間の感光体表面に図示しない露光部材からのレーザー光３Ｃ、３Ｍ、３Ｙ、３Ｋが照射され、感光体１Ｃ、１Ｍ、１Ｙ、１Ｋに静電潜像が形成されるようになっている。そして、このような感光体１Ｃ、１Ｍ、１Ｙ、１Ｋを中心とした４つの画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋが、転写材搬送手段である転写搬送ベルト１０に沿って並置されている。転写搬送ベルト１０は各画像形成ユニット６Ｃ、６Ｍ、６Ｙ、６Ｋの現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋとクリーニング部材５Ｃ、５Ｍ、５Ｙ、５Ｋの間で感光体１Ｃ、１Ｍ、１Ｙ、１Ｋに当接しており、転写搬送ベルト１０の感光体側の裏側に当たる面（裏面）には転写バイアスを印加するための転写ブラシ１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋが配置されている。各画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋは現像装置内部のトナーの色が異なるのと、本発明に係わる黒色トナー像形成用帯電部材２ＫにＤＣ成分のみを印可し、黒色以外のトナー像用帯電部材２Ｃ、２Ｍ、２ＹにＤＣ成分にＡＣ成分を重畳した交番電界を印加するものであり、その他は全て同様の構成となっている。
【０１９０】
図１０に示す構成のカラー電子写真装置において、画像形成動作は次のようにして行われる。まず、各画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋにおいて、感光体１Ｃ、１Ｍ、１Ｙ、１Ｋが矢印方向（感光体と連れ周り方向）に回転する帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋにより帯電され、次に露光部でレーザー光３Ｃ、３Ｍ、３Ｙ、３Ｋにより、作成する各色の画像に対応した静電潜像が形成される。次に現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋにより潜像を現像してトナー像が形成される。現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋは、それぞれＣ（シアン）、Ｍ（マゼンタ）、Ｙ（イエロー）、Ｋ（ブラック）のトナーで現像を行う現像部材で、４つの感光体１Ｃ、１Ｍ、１Ｙ、１Ｋ上で作られた各色のトナー像は転写紙上で重ねられる。転写紙７は給紙コロ８によりトレイから送り出され、一対のレジストローラー９で一旦停止し、上記感光体上への画像形成とタイミングを合わせて転写搬送ベルト１０に送られる。転写搬送ベルト１０上に保持された転写紙７は搬送されて、各感光体１Ｃ、１Ｍ、１Ｙ、１Ｋとの当接位置（転写部）で各色トナー像の転写が行われる。感光体上のトナー像は、転写ブラシ１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋに印加された転写バイアスと感光体１Ｃ、１Ｍ、１Ｙ、１Ｋとの電位差から形成される電界により、転写紙７上に転写される。そして４つの転写部を通過して４色のトナー像が重ねられた記録紙７は定着装置１２に搬送され、トナーが定着されて、図示しない排紙部に排紙される。また、転写部で転写されずに各感光体１Ｃ、１Ｍ、１Ｙ、１Ｋ上に残った残留トナーは、クリーニング装置５Ｃ、５Ｍ、５Ｙ、５Ｋで回収される。
【０１９１】
なお、図１０の例では画像形成要素は転写紙搬送方向上流側から下流側に向けて Ｃ（シアン）、Ｍ（マゼンタ）、Ｙ（イエロー）、Ｋ（ブラック）の色の順で並んでいるが、この順番に限るものでは無く、色順は任意に設定されるものである。また、黒色のみの原稿を作成する際には、黒色以外の画像形成要素（６Ｃ、６Ｍ、６Ｙ）が停止するような機構を設けることは本発明に特に有効に利用できる。更に、図１０において帯電部材は感光体と当接しているが、両者の間に適当なギャップ（１０〜２００μｍ程度）を設けてやることにより、両者の摩耗量が低減できると共に、帯電部材へのトナーフィルミングが少なくて済み良好に使用できる。
【０１９２】
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、各々の電子写真要素は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、除電手段等を含んだ１つの装置（部品）である。
【０１９３】
【実施例】
【０１９４】
以下、本発明を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。
【０１９５】
（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、順次塗布・乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２０μｍの電荷輸送層、５μｍの表面層からなる電子写真感光体を形成した。なお、下引き層、電荷発生層、電荷輸送層は浸漬塗工法で塗工し、表面層はスプレー法にて塗工を行った。
【０１９６】
下引き層塗工液：
二酸化チタン粉末 ４００部
メラミン樹脂 ６５部
アルキッド樹脂 １２０部
２−ブタノン ４００部
【０１９７】
電荷発生層塗工液：
下記構造のビスアゾ顔料 １２部
【０１９８】
【化１５】

ポリビニルブチラール ２部
２−ブタノン ２００部
シクロヘキサノン ４００部
【０１９９】
電荷輸送層塗工液：
Ａ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ８部
【０２００】
【化１６】

テトラヒドロフラン ２００部
【０２０１】
表面層塗工液１：
Ｃ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２０２】
【化１７】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２０３】
表面層塗工液２：
Ｃ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２０４】
【化１８】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ４部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２０５】
表面層塗工液３：
Ｃ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２０６】
【化１９】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ７部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２０７】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により連続的に塗工した。この際連続的とは、下層を塗工後、指触乾燥しないうちに次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２は２μｍ相当ずつ塗工し、表面層塗工液３は１μｍ相当塗工し、合計５μｍの表面層を形成した。
【０２０８】
（実施例２）
実施例１における表面層塗工液１、２、３をそれぞれ以下の組成のものに変更した以外は、実施例１と同様に感光体を作製した。
【０２０９】
表面層塗工液１：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２１０】
【化２０】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） １部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２１１】
表面層塗工液２：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２１２】
【化２１】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２１３】
表面層塗工液３：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２１４】
【化２２】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ３部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２１５】
（比較例１）
実施例１における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例１と全く同様に感光体を作製した。
【０２１６】
（比較例２）
実施例１における表面層を表面層塗工液３のみを用い、５μｍ相当の表面層を形成した以外は、実施例１と全く同様に感光体を作製した。
【０２１７】
（比較例３）
実施例１における表面層塗工液１、２、３に含有されるフィラー（アルミナ微粒子）を以下のものに変更した以外は、実施例１と同様に感光体を作製した。
【０２１８】
フィラー：導電性酸化錫（比抵抗：５×１０^５Ω・ｃｍ、平均一次粒径：０．３μｍ）
【０２１９】
（比較例４）
実施例２における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例２と全く同様に感光体を作製した。
【０２２０】
（比較例５）
実施例２における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例２と全く同様に感光体を作製した。
【０２２１】
以上のように作製した実施例１、２および比較例１〜５の感光体を図５に示す電子写真プロセス（ただし、クリーニング前露光は無し、帯電部材はスコロトロン方式チャージャー）に装着し、画像露光光源を６５５ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、連続して２万枚の印刷を行い、その時の画像を初期と２万枚後に評価した。更に、２万枚おける感光体表面の摩耗量も併せて測定した。以上の結果は、表１に併せて示す。
【０２２２】
【表１】

【０２２３】
（実施例３）
実施例１で使用した図５に示す電子写真プロセスの帯電部材をスコロトロン・チャージャーから帯電ローラーに変更し、帯電ローラーが感光体に接触するように配置した。この装置に実施例１で作製した感光体を搭載し、下記の帯電条件で、実施例１と同様の評価を行った。
【０２２４】
帯電条件：
ＤＣバイアス：−９３０Ｖ
その結果、初期及び２万枚目の画像はいずれも良好であったが、２万枚後の画像には帯電ローラー汚れ（トナーフィルミング）に基づく、ごく僅かな異常画像（地汚れ）が認められた。しかしながら、連続プリント時のオゾン臭は実施例１の場合に比べて、格段に少なかった。
【０２２５】
（実施例４）
実施例３で使用した帯電ローラーの両端部に厚さ５０μｍ、幅５ｍｍの絶縁テープを張り付け、帯電ローラー表面と感光体表面との間に空間的なギャップ（５０μｍ）を有するように配置した。その他の条件は実施例３と全く同様に評価を行った。その結果、実施例３で認められた帯電ローラー汚れは、全く認められず、初期及び２万枚目の画像はいずれも良好であった。しかしながら、２万枚後にハーフトーン画像を出力した際、ごく僅かではあるが、帯電ムラに基づく画像ムラが認められた。
【０２２６】
（実施例５）
実施例４の評価において、帯電条件を以下のように変更した以外は実施例４と同様の評価を行った。
【０２２７】
帯電条件：
ＤＣ バイアス：−９００Ｖ
ＡＣ バイアス：２．０ｋＶ （ｐｅａｋ ｔｏ ｐｅａｋ）、周波数２ｋＨｚ
初期及び２万枚後の画像は良好であった。実施例３で認められた帯電ローラー汚れ、実施例４で認められたハーフトーン画像ムラは、全く認められなかった。
【０２２８】
（参考例１）
ニッケルベルト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、順次塗布・乾燥し、３μｍの下引き層、０．３μｍの電荷発生層、２２μｍの電荷輸送層、３μｍの表面層からなる電子写真感光体を形成した。なお、下引き層、電荷発生層、電荷輸送層は浸漬塗工法で塗工し、表面層はスプレー法にて塗工を行った。
【０２２９】
下引き層塗工液：
二酸化チタン粉末 １００部
アルコール可溶性ナイロン １００部
メタノール ５００部
ブタノール ３００部
【０２３０】
電荷発生層塗工液：
下記構造のビスアゾ顔料 １０部
【０２３１】
【化２３】

ポリビニルブチラール ２部
２−ブタノン ２００部
シクロヘキサノン ４００部
【０２３２】
電荷輸送層塗工液：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２３３】
【化２４】

テトラヒドロフラン ２００部
【０２３４】
表面層塗工液１：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０２３５】
【化２５】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．３μｍ） １．５部
トルエン ６００部
【０２３６】
表面層塗工液２：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０２３７】
【化２６】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．３μｍ） ４部
トルエン ６００部
【０２３８】
表面層塗工液３：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０２３９】
【化２７】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．３μｍ） ７部
トルエン ６００部
【０２４０】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により連続的に塗工した。この際連続的とは、下層を塗工後、指触乾燥しないうちに、次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２、３は１μｍ相当ずつ塗工し、合計３μｍの表面層を形成した。
【０２４１】
（参考例２）
参考例１における表面層塗工液１、２、３をそれぞれ以下の組成のものに変更した以外は、参考例１と同様に感光体を作製した。
【０２４２】
表面層塗工液１：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３５０００） ７部
【０２４３】
【化２８】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．３μｍ） １部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２４４】
表面層塗工液２：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３５０００） ７部
【０２４５】
【化２９】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．５μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２４６】
表面層塗工液３：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３５０００） ７部
【０２４７】
【化３０】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．３μｍ） ３部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２４８】
（比較例６）
参考例１における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例１と全く同様に感光体を作製した。
【０２４９】
（比較例７）
参考例１における表面層を表面層塗工液３のみを用い、３μｍ相当の表面層を形成した以外は、参考例１と全く同様に感光体を作製した。
【０２５０】
（比較例８）
参考例１における表面層を積層せず、電荷輸送層を２５μｍとした以外は、参考例１と同様に感光体を作製した。
【０２５１】
（比較例９）
参考例１における表面層塗工液１、２、３に含有されるフィラー（酸化チタン微粒子）を以下のものに変更した以外は、参考例１と同様に感光体を作製した。
【０２５２】
フィラー：導電性酸化チタン（比抵抗：７．１×１０^７Ω・ｃｍ）
【０２５３】
（比較例１０）
参考例２における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例２と全く同様に感光体を作製した。
【０２５４】
（比較例１１）
参考例２における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例２と全く同様に感光体を作製した。
【０２５５】
以上のように作製した参考例１、２および比較例６〜１０の感光体を図６に示す電子写真プロセス（ただし、クリーニング前露光は無し）に装着し、画像露光光源を６５５ｎｍのＬＥＤとして、連続して３万枚の印刷を行い、その時の画像を初期と３万枚後に評価した。更に、３万枚おける感光体表面の摩耗量も併せて測定した。以上の結果は、表２に併せて示す。
【０２５６】
【表２】

【０２５７】
（参考例３、４）
参考例１に使用したフィラー（酸化チタン微粒子）に処理量が２０ｗｔ％になるようにチタネート系カップリング剤およびＡｌ_２Ｏ_３による表面処理を行った。このフィラーを用いて、参考例１における表面層塗工液１、２、３を作製した。これらについて、塗工液中の平均粒径（堀場製作所社製：ＣＡＰＡ７００で測定）、塗工液の沈降性（試験管内で静置した塗工液粒子の沈降度合いを肉眼で確認）について評価した。結果を表３に示す。なお、表３に示される値は、それぞれの表面層塗工液３の測定結果である。
【０２５８】
【表３】

【０２５９】
（参考例５、６）
参考例３、４で作製した分散液を用い、参考例１と同様に感光体を作製した。また、透過率測定用サンプルとして、表面層のみをポリエステルフィルム上に形成した。感光体の外観結果、表面粗さＲｚと６５５ｎｍにおける透過率を表４に示す。
【０２６０】
【表４】

【０２６１】
（参考例７、８）
参考例５、６で作製した感光体を先の参考例１の評価に用いた装置と同じものに搭載し、画像評価を行った。その結果、参考例１の分散液を用いた感光体より、参考例３、４の分散液を用いた感光体の解像度が勝っていた。
【０２６２】
（実施例６）
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、順次塗布・乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２１μｍの電荷輸送層および４μｍの表面層からなる電子写真感光体を形成した。
【０２６３】
下引き層塗工液：
二酸化チタン粉末 ４００部
メラミン樹脂 ６５部
アルキッド樹脂 １２０部
２−ブタノン ４００部
【０２６４】
電荷発生層塗工液：
図８で表わされたＸＤスペクトルを有するチタニルフタロシアニン ８部
ポリビニルブチラール ５部
２−ブタノン ４００部
【０２６５】
電荷輸送層塗工液：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２６６】
【化３１】

塩化メチレン ８０部
【０２６７】
表面層塗工液１：
ポリアリレート １０部
下記構造式の電荷輸送物質 ８部
【０２６８】
【化３２】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２６９】
表面層塗工液２：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ８部
【０２７０】
【化３３】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ４部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２７１】
表面層塗工液３：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ８部
【０２７２】
【化３４】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ８部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２７３】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により連続的に塗工した。この際連続的とは、下層を塗工後、指触乾燥しないうちに、次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２は１．５μｍ相当ずつ塗工し、表面層塗工液３は１μｍ相当塗工し、合計４μｍの表面層を形成した。
【０２７４】
（比較例１２）
実施例６における表面層を表面層塗工液１のみを用い、４μｍ相当の表面層を形成した以外は、実施例６と全く同様に感光体を作製した。
【０２７５】
（比較例１３）
実施例６における表面層を表面層塗工液３のみを用い、４μｍ相当の表面層を形成した以外は、実施例６と全く同様に感光体を作製した。
【０２７６】
（比較例１４）
実施例６における表面層を積層せず、電荷輸送層を２５μｍとした以外は、実施例６と同様に感光体を作製した。
【０２７７】
以上のように作製した実施例６および比較例１２〜１４の感光体を第５図に示す電子写真プロセス用カートリッジに装着し、画像露光光源を７８０ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、連続して２万枚の印刷を行い、その時の画像を初期と２万枚後に評価した。更に、２万枚における感光体表面の摩耗量も併せて測定した。以上の結果は、表５に併せて示す。
【０２７８】
【表５】

【０２７９】
（実施例７）
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、順次塗布・乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２０μｍの電荷輸送層、５μｍの表面層からなる電子写真感光体を形成した。なお、下引き層、電荷発生層、電荷輸送層は浸漬塗工法で塗工し、表面層はスプレー法にて塗工を行った。
【０２８０】
下引き層塗工液：
二酸化チタン粉末 ４００部
メラミン樹脂 ６５部
アルキッド樹脂 １２０部
２−ブタノン ４００部
【０２８１】
電荷発生層塗工液：
下記構造のビスアゾ顔料 １０部
【０２８２】
【化３５】

ポリビニルブチラール ２部
２−ブタノン ２００部
シクロヘキサノン ４００部
【０２８３】
電荷輸送層塗工液：
Ａ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ８部
【０２８４】
【化３６】

テトラヒドロフラン ２００部
【０２８５】
表面層塗工液１：
Ａ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２８６】
【化３７】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２８７】
表面層塗工液２：
Ａ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２８８】
【化３８】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ４部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２８９】
表面層塗工液３：
Ａ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０２９０】
【化３９】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ７部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２９１】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により順次塗工した。この際順次塗工とは、下層を塗工後、指触乾燥が完了したら次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２は２μｍ相当ずつ塗工し、表面層塗工液３は１μｍ相当塗工し、合計５μｍの表面層を形成した。
【０２９２】
（実施例８）
実施例７における表面層塗工液１、２、３をそれぞれ以下の組成のものに変更した以外は、実施例７同様に感光体を作製した。
【０２９３】
表面層塗工液１：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２９４】
【化４０】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） １部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２９５】
表面層塗工液２：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２９６】
【化４１】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２９７】
表面層塗工液３：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０２９８】
【化４２】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．３μｍ） ３部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０２９９】
（比較例１５）
実施例７における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例７と全く同様に感光体を作製した。
【０３００】
（比較例１６）
実施例７における表面層を表面層塗工液３のみを用い、５μｍ相当の表面層を形成した以外は、実施例７と全く同様に感光体を作製した。
【０３０１】
（比較例１７）
実施例７における表面層塗工液１、２、３に含有されるフィラー（アルミナ微粒子）を以下のものに変更した以外は、実施例７と同様に感光体を作製した。
フィラー：導電性酸化錫（比抵抗：５×１０^５Ω・ｃｍ、平均一次粒径：０．３μｍ）
【０３０２】
（比較例１８）
実施例８における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例８と全く同様に感光体を作製した。
【０３０３】
（比較例１９）
実施例８における表面層を表面層塗工液１のみを用い、５μｍ相当の表面層を形成した以外は、実施例８と全く同様に感光体を作製した。
【０３０４】
以上のように作製した実施例７、８および比較例１５〜１９の感光体を図５に示す電子写真プロセス（ただし、クリーニング前露光は無し、帯電部材はスコロトロン方式チャージャー）に装着し、画像露光光源を６５５ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、連続して２万枚の印刷を行い、その時の画像を初期と２万枚後に評価した。更に、２万枚おける感光体表面の摩耗量も併せて測定した。以上の結果は、表６に併せて示す。
【０３０５】
【表６】

【０３０６】
（実施例９）
実施例７で使用した図５に示す電子写真プロセスの帯電部材をスコロトロン・チャージャーから帯電ローラーに変更し、帯電ローラーが感光体に接触するように配置した。この装置に実施例７で作製した感光体を搭載し、下記の帯電条件で、実施例７と同様の評価を行った。
【０３０７】
帯電条件：
ＤＣバイアス：−９３０Ｖ
その結果、初期及び２万枚目の画像はいずれも良好であったが、２万枚後の画像には帯電ローラー汚れ（トナーフィルミング）に基づく、ごく僅かな異常画像（地汚れ）が認められた。しかしながら、連続プリント時のオゾン臭は実施例７の場合に比べて、格段に少なかった。
【０３０８】
（実施例１０）
実施例９で使用した帯電ローラーの両端部に厚さ５０μｍ、幅５ｍｍの絶縁テープを張り付け、帯電ローラー表面と感光体表面との間に空間的なギャップ（５０μｍ）を有するように配置した。その他の条件は実施例９と全く同様に評価を行った。その結果、実施例９で認められた帯電ローラー汚れは、全く認められず、初期及び２万枚目の画像はいずれも良好であった。しかしながら、２万枚後にハーフトーン画像を出力した際、ごく僅かではあるが、帯電ムラに基づく画像ムラが認められた。
【０３０９】
（実施例１１）
実施例１０の評価において、帯電条件を以下のように変更した以外は実施例１０と同様の評価を行った。
【０３１０】
帯電条件：
ＤＣバイアス：−９００Ｖ
ＡＣバイアス：２．０ｋＶ （ｐｅａｋ ｔｏ ｐｅａｋ）、周波数２ｋＨｚ
初期及び２万枚後の画像は良好であった。実施例９で認められた帯電ローラー汚れ、実施例１０で認められたハーフトーン画像ムラは、全く認められなかった。
【０３１１】
（参考例９）
ニッケルベルト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、順次塗布・乾燥し、３μｍの下引き層、０．３μｍの電荷発生層、２２μｍの電荷輸送層、３μｍの表面層からなる電子写真感光体を形成した。なお、下引き層、電荷発生層、電荷輸送層は浸漬塗工法で塗工し、表面層はスプレー法にて塗工を行った。
【０３１２】
下引き層塗工液：
二酸化チタン粉末 １００部
アルコール可溶性ナイロン １００部
メタノール ５００部
ブタノール ３００部
【０３１３】
電荷発生層塗工液：
下記構造のビスアゾ顔料 １０部
【０３１４】
【化４３】

ポリビニルブチラール ２部
２−ブタノン ２００部
シクロヘキサノン ４００部
【０３１５】
電荷輸送層塗工液：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０３１６】
【化４４】

テトラヒドロフラン ２００部
【０３１７】
表面層塗工液１：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０３１８】
【化４５】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均１次粒径：０．４μｍ） １．５部
トルエン ６００部
【０３１９】
表面層塗工液２：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０３２０】
【化４６】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．４μｍ） ４部
トルエン ６００部
【０３２１】
表面層塗工液３：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ６部
【０３２２】
【化４７】

酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．４μｍ） ７部
トルエン ６００部
【０３２３】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により順次塗工した。この際順次塗工とは、下層を塗工後、指触乾燥が完了したら、次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２、３は１μｍ相当ずつ塗工し、合計３μｍの表面層を形成した。
【０３２４】
（参考例１０）
参考例９における表面層塗工液１、２、３をそれぞれ以下の組成のものに変更した以外は、参考例９と同様に感光体を作製した。
【０３２５】
表面層塗工液１：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０３２６】
【化４８】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．３μｍ） １部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３２７】
表面層塗工液２：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０３２８】
【化４９】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．４μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３２９】
表面層塗工液３：
下記構造式の高分子電荷輸送物質（Ｍｗ＝１３００００） ７部
【０３３０】
【化５０】

シリカ微粒子（比抵抗：４×１０^１３Ω・ｃｍ、
平均一次粒径：０．４μｍ） ３部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３３１】
（比較例２０）
参考例９における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例９と全く同様に感光体を作製した。
【０３３２】
（比較例２１）
参考例９における表面層を表面層塗工液３のみを用い、３μｍ相当の表面層を形成した以外は、参考例９と全く同様に感光体を作製した。
【０３３３】
（比較例２２）
参考例９における表面層を積層せず、電荷輸送層を２５μｍとした以外は、参考例９と同様に感光体を作製した。
【０３３４】
（比較例２３）
参考例９における表面層塗工液１、２、３に含有されるフィラー（酸化チタン微粒子）を以下のものに変更した以外は、参考例９と同様に感光体を作製した。
【０３３５】
フィラー：導電性酸化チタン（比抵抗：７．１×１０^７Ω・ｃｍ）
【０３３６】
（比較例２４）
参考例１０における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例１０と全く同様に感光体を作製した。
【０３３７】
（比較例２５）
参考例１０における表面層を表面層塗工液１のみを用い、３μｍ相当の表面層を形成した以外は、参考例１０と全く同様に感光体を作製した。
【０３３８】
以上のように作製した参考例９、１０および比較例２０〜２５の感光体を図６に示す電子写真プロセス（ただし、クリーニング前露光は無し）に装着し、画像露光光源を６５５ｎｍのＬＥＤとして、連続して３万枚の印刷を行い、その時の画像を初期と３万枚後に評価した。更に、３万枚おける感光体表面の摩耗量も併せて測定した。以上の結果は、表７に併せて示す。
【０３３９】
【表７】

【０３４０】
（参考例１１、１２）
参考例９に使用したフィラーに処理量が２０ｗｔ％になるようにチタネート系カップリング剤およびＡｌ_２Ｏ_３による表面処理を行った。このフィラーを用いて、参考例９における表面層塗工液１、２、３を作製した。これらについて、塗工液中の平均粒径（堀場製作所社製：ＣＡＰＡ７００で測定）、塗工液の沈降性（試験管内で静置した塗工液粒子の沈降度合いを肉眼で確認）について評価した。結果を表８に示す。なお、表８に示される値は、それぞれの表面層塗工液３の測定結果である。
【０３４１】
【表８】

【０３４２】
（参考例１３、１４）
参考例１１、１２で作製した分散液を用い、参考例９と同様に感光体を作製した。また、透過率測定用サンプルとして、表面層のみをポリエステルフィルム上に形成した。感光体の外観結果、表面粗さＲｚと６５５ｎｍにおける透過率を表９に示す。
【０３４３】
【表９】

【０３４４】
（参考例１５、１６）
参考例１３、１４で作製した感光体を先の参考例９の評価に用いた装置と同じものに搭載し、画像評価を行った。その結果、参考例９の分散液を用いた感光体より、参考例１３、１４の分散液を用いた感光体の解像度が勝っていた。
【０３４５】
（実施例１２）
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、順次塗布・乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２１μｍの電荷輸送層および４μｍの表面層からなる電子写真感光体を形成した。
【０３４６】
下引き層塗工液：
二酸化チタン粉末 ４００部
メラミン樹脂 ６５部
アルキッド樹脂 １２０部
２−ブタノン ４００部
【０３４７】
電荷発生層塗工液：
図８で表わされたＸＤスペクトルを有するチタニルフタロシアニン ８部
ポリビニルブチラール ５部
２−ブタノン ４００部
【０３４８】
電荷輸送層塗工液：
Ｚ型ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【０３４９】
【化５１】

塩化メチレン ８０部
【０３５０】
表面層塗工液１：
ポリアリレート １０部
下記構造式の電荷輸送物質 ８部
【０３５１】
【化５２】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．４μｍ） ２部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３５２】
表面層塗工液２：
ポリアリレート １０部
下記構造式の電荷輸送物質 ８部
【０３５３】
【化５３】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．４μｍ） ４部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３５４】
表面層塗工液３：
ポリアリレート １０部
下記構造式の電荷輸送物質 ８部
【０３５５】
【化５４】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．４μｍ） ８部
テトラヒドロフラン ４００部
シクロヘキサノン ２００部
【０３５６】
上記表面層塗工液は、表面層塗工液１、２、３の順に３つのスプレーヘッドを用い、スプレー法により順次塗工した。この際順次塗工とは、下層を塗工後、指触乾燥が完了したら、次の塗工液をスプレー法により積層することを指す。なお、表面層塗工液１、２は１．５μｍ相当ずつ塗工し、表面層塗工液３は１μｍ相当塗工し、合計４μｍの表面層を形成した。
【０３５７】
（比較例２６）
実施例１２における表面層を表面層塗工液１のみを用い、４μｍ相当の表面層を形成した以外は、実施例１２と全く同様に感光体を作製した。
【０３５８】
（比較例２７）
実施例１２における表面層を表面層塗工液３のみを用い、４μｍ相当の表面層を形成した以外は、実施例１２と全く同様に感光体を作製した。
【０３５９】
（比較例２８）
実施例１２における表面層を積層せず、電荷輸送層を２５μｍとした以外は、実施例１２と同様に感光体を作製した。
【０３６０】
以上のように作製した実施例１２および比較例２６〜２８の感光体を図５に示す電子写真プロセス用カートリッジに装着し、画像露光光源を７８０ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、連続して２万枚の印刷を行い、その時の画像を初期と２万枚後に評価した。更に、２万枚における感光体表面の摩耗量も併せて測定した。以上の結果は、表１０に併せて示す。
【０３６１】
【表１０】

【０３６２】
（実施例１３）
実施例１２において、導電性支持体（ＪＩＳ１０５０）を以下の陽極酸化皮膜処理を行い、次いで下引き層を設けずに、実施例１２と同様に電荷発生層、電荷輸送層、保護層を設け、感光体を作製した。
【０３６３】
［陽極酸化皮膜処理］
支持体表面の鏡面研磨仕上げを行い、脱脂洗浄、水洗浄を行った後、液温２０℃、硫酸１５ｖｏｌ％の電解浴に浸し、電解電圧１５Ｖにて３０分間陽極酸化皮膜処理を行った。更に、水洗浄を行った後、７％の酢酸ニッケル水溶液（５０℃）にて封孔処理を行った。その後純水による洗浄を経て、６μｍの陽極酸化皮膜が形成された支持体を得た。
【０３６４】
実施例１２、実施例１３で作製した感光体を図７に示す電子写真プロセス用カートリッジに装着し、画像露光光源を７８０ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、連続して２万枚の印刷を行い、その時の画像を初期と２万枚後に評価した。両者の２万枚後の画像を比較すると、いずれも実使用上問題無いものであるが、地肌部の汚れ（黒点）が、実施例１３の画像に比べ、実施例１２の方がわずかに多かった。
【０３６５】
（実施例１４）
実施例１で作製した感光体を図１０に示す電子写真装置に搭載し、４つすべての画像形成要素は以下に示すプロセス条件にてフルカラー画像２００００枚の画像評価を行った。結果を表１１に示す。
【０３６６】
・帯電条件
ＤＣバイアス：−８００Ｖ
ＡＣバイアス：２．０ｋＶ（ｐｅａｋ ｔｏ ｐｅａｋ）、周波数２ｋＨｚ
・露光条件
６５５ｎｍの半導体レーザー（ポリゴンミラーによる画像書き込み）
【０３６７】
（比較例２９）
実施例１４で使用した感光体に変えて、比較例１で作製した感光体を使用した以外は、実施例１４と同様に画像評価試験を行った。結果を表１１に示す。
【０３６８】
（比較例３０）
実施例１４で使用した感光体に変えて、比較例２で作製した感光体を使用した以外は、実施例１４と同様に画像評価試験を行った。結果を表１１に示す。
【０３６９】
【表１１】

【０３７０】
【発明の効果】
【０３７１】
本発明によれば、有機系感光体の高耐久化のために表面層にフィラーを添加した感光体において発生する副作用（耐摩耗性と残留電位発生、耐摩耗性向上と画像ボケの発生などのトレード・オフの関係）を、表面層中のフィラー濃度を感光層側から表面側に向かい連続的に高くなるような濃度傾斜を持たせた構成にすることにより、或いは、表面層を複数層の構成とし、フィラー濃度を感光層側から表面側に向かい順次高くなるような構成にすることにより、両立させることが可能になった。これにより、高耐久で繰り返し使用に対し安定な高画質画像を作像できる感光体が提供される。また、繰り返し使用においても安定な高画質画像を高速で作像可能な電子写真方法、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が提供される。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の層構成を表わした図である。
【図２】本発明の別の電子写真感光体の層構成を表わした図である。
【図３】本発明の別の電子写真感光体の層構成を表わした図である。
【図４】本発明のさらに別の電子写真感光体の層構成を表わした図である。
【図５】本発明の電子写真装置を説明するための図である。
【図６】本発明の別の電子写真装置を説明するための図である。
【図７】本発明のプロセスカートリッジを説明するための図である。
【図８】実施例６及び１２で用いたチタニルフタロシアニンのＸ線回折スペクトルを表わした図である。
【図９】帯電部材側にギャップ形成部材を配置した近接帯電機構の一例を説明するための図である。
【図１０】本発明のフルカラー電子写真装置の説明するための図である。
【符号の説明】
（図１〜図４において）
３１ 導電性支持体
３３ 単層感光層
３５ 電荷発生層
３７ 電荷輸送層
３９ 表面層
（図９において）
２９ 感光体
３０ 帯電ローラー
３１ ギャップ形成部材
３２ 金属シャフト
３３ 画像形成領域
３４ 非画像形成領域
（図１０において）
１ ドラム状感光体
２ 帯電部材
３ レーザー光
４ 現像部材
５ クリーニング部材
６ 画像形成要素
７ 転写紙
８ 給紙コロ
９ レジストローラー
１０ 転写搬送ベルト
１１ 転写ブラシ
１２ 定着装置[0001]
BACKGROUND OF THE INVENTION
[0002]
The present invention relates to an electrophotographic photosensitive member having high sensitivity, high resolution, and high durability. The present invention also relates to an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge using a photoconductor provided with a surface layer having a specific configuration.
[0003]
[Prior art]
[0004]
As the electrophotographic method, the Carlson process and various deformation processes thereof are known, and are widely used in copying machines, printers, and the like. Among the photoreceptors used in such electrophotographic methods, those using organic photosensitive materials have begun to be used in recent years due to advantages such as low cost, mass productivity, and non-pollution. Organic electrophotographic photoreceptors include photoconductive resins represented by polyvinylcarbazole (PVK), charge transfer complex types represented by PVK-TNF (2,4,7-trinitrofluorenone), phthalocyanine-binders Are known, such as a pigment dispersion type, a function separation type photoreceptor using a combination of a charge generation material and a charge transport material, and the function separation type photoreceptor is attracting attention.
[0005]
The mechanism of electrostatic latent image formation in this function-separated type photoreceptor is that when the photoreceptor is charged and irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generation material in the charge generation layer, The charge-generating substance that has absorbed the light generates charge carriers, which are injected into the charge transport layer, move in the charge transport layer according to the electric field generated by the charge, and neutralize the charge on the surface of the photoreceptor. Thus, an electrostatic latent image is formed. In the function-separated type photoreceptor, it is known and useful to use a combination of a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region.
[0006]
In recent years, there has been a demand for a reduction in the diameter of a photoconductor, and an increase in durability (life extension) of a machine and a photoconductor. As described above, organic photoreceptors have been steadily improved in sensitivity and electrostatic durability by vigorous development of materials. However, the current ability is not necessarily sufficient in terms of mechanical durability, particularly wear resistance. In view of this point, a photoconductor having a function of improving mechanical durability on the surface of an organic photoconductor has been proposed. Many of these studies have been made on the types of binder resins used for the outermost layer of the photoreceptor, but they have not always been satisfactory.
[0007]
Another way of thinking is to use a protective layer on the outermost surface of the photoreceptor. Examination of a protective layer as a surface layer of a photoreceptor starts with an inorganic photoreceptor, and is described in, for example, Japanese Patent Publication No. 2-3171, Japanese Patent Publication No. 2-7058, Japanese Patent Publication No. 3-43618, and the like. Yes. Thus, when a protective layer was provided on the surface of the inorganic photoreceptor, a filler having a relatively low resistance was used favorably for the protective layer. For this reason, when the photosensitive member is charged, the protective layer bulk or the protective layer / inorganic photosensitive layer interface is often charged rather than charged on the surface of the photosensitive member. Certainly, when the latent image is formed not inside the photoconductor surface but inside the protective layer (including the interface with the inorganic photoconductive layer), the merit that the influence of the photoconductor surface shape (such as scratches) is reduced is found. It was. However, when an attempt is made to give the surface layer a function as a protective layer, it is necessary to add a large amount of a conductive metal oxide as a filler to be added to the surface layer. In this case, even if the transparency of the surface layer is ensured by the selection of the material, the bulk or surface resistance of the surface layer is lowered, so that a defect of image blur may appear during repeated use. In order to eliminate such drawbacks, Japanese Patent Publication No. 2-7057 and Japanese Patent No. 2675035 disclose a method of changing the conductive metal oxide concentration in the surface layer in the depth direction from the coating film surface. ing. As a result, the image blur / flow is eliminated.
[0008]
Further, as a method for eliminating image blur by in-process processing, means for mounting a drum heater for heating a 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 necessitates an increase in the size of the device, resulting in a significant increase in power consumption and the fact that it takes a lot of time to start up the device. It was. On the other hand, a surface layer (protective layer) using a low-resistance filler is laminated on a photoreceptor (generally called OPC) using an organic charge generating material and a charge transport material by applying the above-described technique. When the repeated use test was performed, image flow occurred due to poor matching with OPC. In addition, even when a method of providing a concentration distribution in the surface layer of the conductive metal oxide, which was effective for an inorganic photoreceptor, the results were almost the same.
[0009]
Although the details of the above cause are unknown, the method of Japanese Patent No. 2675035 has a configuration in which the direction of filler concentration distribution in the surface layer is opposite to that of the present invention, and the concentration is low toward the surface side. . For this reason, the abrasion resistance of the surface of the photoreceptor is not so high, and the surface is likely to be scratched, and in the repeated use, the low resistance substance generated based on the reactive gas generated from the charger etc. is likely to accumulate. It is estimated that In the case of the method of Japanese Patent Publication No. 2-7057, the filler concentration distribution in the surface layer is in the same direction as the present invention, but the specific resistance of the filler used is small, and the conductivity is low. It is shown. Moreover, the filler density | concentration in the surface contains 40 weight% or more. For this reason, the surface resistance or bulk resistance in the surface layer is very small, and it is presumed that the image flow has occurred in repeated use. In a recent electrophotographic process using an organic photoreceptor, a digital signal is used by dot-writing on the photoreceptor, and such a use situation is a situation where an inorganic photoreceptor is the mainstream of the photoreceptor. Is very different. It can be said that the resolution level required from the machine side has changed greatly, and this phenomenon (defect) has become prominent.
[0010]
Under such circumstances, it is essential to use a filler having high resistance instead of conductivity for the surface layer of the organic photoreceptor. However, when a highly resistive filler is used, there may be a problem that the residual potential increases. The increase in the residual potential that is often observed leads to a high bright portion potential in the electrophotographic apparatus, which leads to a decrease in image density and gradation. 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.
[0011]
As a method of suppressing the increase in residual potential in the prior art, a method using a protective layer as a photoconductive layer (Japanese Patent Publication No. 44-834, Japanese Patent Publication No. 43-16198, Japanese Patent Publication No. 49-10258) is disclosed. ing. However, since the amount of light reaching the photosensitive layer is reduced by the absorption of light by the protective layer, there is a problem that the sensitivity of the photosensitive member is lowered, and the effect is slight.
[0012]
On the other hand, by making the average particle size of the metal or metal oxide contained as the filler 0.3 μm or less, the protective layer becomes substantially transparent and suppresses the accumulation of residual potential (Japanese Patent Laid-Open No. 57-57). No. 30846). Although this method has an effect of suppressing an increase in the residual potential, the effect is insufficient, and the actual situation is that the problem has not been solved. This is because the increase in the residual potential caused when the filler is contained is more likely to be caused by charge traps and filler dispersibility due to the presence of the filler than the charge generation efficiency. Even if the average particle size of the filler is 0.3 μm or more, it is possible to obtain transparency by increasing the dispersibility, and even if the average particle size is 0.3 μm or less, the filler is considerably aggregated. If this is the case, the transparency of the film will be reduced.
[0013]
In addition, a method (JP-A-4-281461) is disclosed in which a protective layer contains a charge transport material together with a filler to suppress an increase in residual potential while providing mechanical strength. The addition of the charge transport material to the protective layer is effective in improving the charge mobility and is an effective method for reducing the residual potential. However, if the increase in residual potential caused by the inclusion of filler is attributed to an increase in resistance due to the presence of filler or an increase in charge trapping sites, it increases the charge mobility and increases the residual potential. There is a limit to the suppression. Accordingly, the thickness of the protective layer and the filler content must be reduced, and the actual situation is that the required durability has not been satisfied.
[0014]
As another means for suppressing the residual potential rise, 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. 55-55). 157748), a method of containing an electron accepting substance (Japanese Patent Laid-Open No. 2-4275), and a method of containing a wax having an acid value of 5 (mg KOH / g) or less (Japanese Patent Laid-Open No. 2000-66434). Has been. These methods improve the charge injectability at the protective layer / charge transport layer interface, and because the low resistance portion is formed in the protective layer, the charge easily reaches the surface. It is believed 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. Moreover, since it becomes easy to cause the dispersibility fall of a filler when adding an organic acid, the effect is not enough and it is the actual condition that it has not resulted in the solution of a subject.
[0015]
In addition, in order to achieve high image quality in an electrophotographic photosensitive member containing a filler for high durability, not only the above-mentioned image blurring and residual potential increase are suppressed, but also the charge is protected. It is also important that the charge reaches the surface of the photoreceptor linearly without being hindered by the filler inside. This is greatly influenced by the dispersibility of the filler in the protective layer film. In the state where the filler is aggregated, when the charge injected into the protective layer from the charge transport layer moves to the surface, the progress is easily hindered by the filler, and as a result, the dots formed by the toner are scattered. The resolution is greatly reduced. In addition, when the protective layer is provided, if the writing light is scattered by the filler and the light transmittance is lowered, the resolution is similarly adversely affected. However, the influence on the light transmittance is also affected by the filler. It is closely related to dispersibility. Further, the dispersibility of the filler greatly affects the wear resistance, the filler causes strong aggregation, and the wear resistance is greatly lowered in a state where the dispersibility is poor. Therefore, in the electrophotographic photosensitive member in which a protective layer containing a filler for high durability is formed, in order to realize high image quality at the same time, not only the generation of image blur and the increase in residual potential are suppressed, It is important to increase the dispersibility of the filler in the protective layer film.
[0016]
However, effective means that can solve them simultaneously have not been found, and when filler is included in the outermost surface layer of the photoreceptor for high durability, the effect of image blur and residual potential rise appears strongly, The reality is that there are still issues with high image quality. In addition, since it is necessary to install a drum heater to reduce these effects, the high durability of the small-diameter photoreceptor, which is required to be the most durable, has not been realized. In fact, it has become a major obstacle to reducing power consumption.
[0017]
In addition, it is an organic photoconductor that has surpassed inorganic photoconductors in terms of photosensitivity, spectral sensitivity range, pollution-free property, electrostatic durability, etc., but mechanical durability is required to make full use of its advantages. Improving performance is an urgent issue, and its development has been eagerly awaited for the design of highly durable machines and processes.
[0018]
As a full-color image forming apparatus using an electrophotographic system, two systems are generally known. One is a so-called single method or single drum method, in which one electrophotographic photosensitive member is mounted in the apparatus and four color developing members are mounted. In this method, four colors (cyan, magenta, yellow, and black) on the photosensitive member or on the transfer target member (directly transferred to the output paper or once transferred to the intermediate transfer member and then transferred to the paper) are used. A toner image is formed. In this case, the charging member, the exposure member, the transfer member, the cleaning member, and the fixing member arranged around the photosensitive member can be shared, and are designed to be smaller and less expensive than the tandem method described later. Is possible.
[0019]
On the other hand, another system is called a tandem system or a tandem drum system. This is one in which a plurality of electrophotographic photosensitive members are mounted at least in the apparatus. In general, each drum, one member for charging, exposure, development, and cleaning, is arranged on one drum to form one electrophotographic element, and a plurality (generally four) of them are mounted. Has been. In this method, a single color toner image is formed by one electrophotographic element, and the toner image is sequentially transferred to a transfer target to form a full color image. The merit of this method is that high-speed image formation is possible. This is because the toner images of the respective colors can be produced by parallel processing as described above. For this reason, compared with the single method, the image forming processing time is about one-fourth, and it is possible to cope with four times higher speed printing. The second merit is that the durability of each member provided in the electrophotographic element including the photoreceptor can be substantially increased. This is because, in the single method, each process of charging, exposure, and development is performed four times with one photoconductor to form one full color image, whereas in the tandem method, the above operation is performed once with one photoconductor. This is because they only do it. However, it also has the demerit that the entire device becomes large and the cost becomes high. As for the size of the entire apparatus, measures have been taken by reducing the diameter of the photosensitive member, reducing the size of each member installed around the photosensitive member, and reducing the size of one electrophotographic element. As a result, the effect of reducing the material cost as well as the size of the device has been produced, and the cost of the entire device has been reduced somewhat. However, with the downsizing and miniaturization of the apparatus, a new problem has arisen that the durability of each member including the photoreceptor mounted on the electrophotographic element has to be increased.
[0020]
Furthermore, in tandem image formation, since a plurality of image forming elements must be simultaneously formed, the plurality of image forming elements have substantially the same characteristics even at the beginning and after aging (repeated use). There is also the problem of having to. The most influential in this regard is the electrostatic properties of the photoreceptor in the image forming element. A large variation in the characteristics of the photoconductor used for a plurality of image forming elements changes the color balance of the output image, which is fatal for a full-color image forming apparatus in which color reproducibility differs from the input original drawing. Problems would occur.
[0021]
[Problems to be solved by the invention]
[0022]
An object of the present invention is to provide a photoconductor that can form a high-quality image that is highly durable and stable for repeated use. Specifically, the present invention provides a photoconductor that has high durability, suppresses image deterioration due to residual potential increase or image blurring, and can stably obtain a high-quality image even when used repeatedly for a long period of time. It is in. Another object of the present invention is to provide a photoreceptor having good color reproducibility even after repeated use in a tandem image forming apparatus. Another object of the present invention is to eliminate the need for replacement of the photosensitive member by using those photosensitive members, and to realize downsizing of the apparatus accompanying high-speed printing or a reduction in the diameter of the photosensitive member, and also in repeated use. It is an object of the present invention to provide an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge capable of stably obtaining a high-quality image.
[0023]
[Means for Solving the Problems]
[0024]
As a result of further studies based on the results obtained in the past as described above, the present inventors have found the following. That is, when a surface layer such as a protective layer is provided on the organic photosensitive layer, it is necessary to add a filler for the purpose of imparting abrasion resistance. However, the specific resistance as used in the inorganic photosensitive member is required. When a small material (conductive material) is used, an abnormal image such as image blur or image flow is generated during initial or repeated use. Therefore, it is necessary to use a filler having a large specific resistance. However, when a filler having a large specific resistance is used, an abnormal image such as image blur can be avoided, but a new problem that a residual potential (post-exposure potential) becomes high has occurred.
[0025]
Inorganic photoreceptors that have been used in the past have been used with positive charge regardless of the presence or absence of a protective layer. On the other hand, both the hole transport type and the electron transport type have been developed as the charge transport material used in the organic photoreceptor, but the one that has actually reached the practical level is the hole transport type. For this reason, in the function-separated laminated photoconductor designed to make the best use of the characteristics of OPC, negative charge occupies most of it. Some single-layer photosensitive layers and reverse-layer photosensitive layers have been developed, but are not the mainstream.
[0026]
As described above, one of the reasons why the protective layer technology developed for inorganic photoreceptors cannot be applied horizontally to organic photoreceptors is probably due to this charged polarity. That is, the charging potential is used at substantially the same level for both the inorganic photoreceptor and the organic photoreceptor. At this time, when considering the discharge efficiency of the charger, as a general rule, the positive charge has a higher charge efficiency. In addition, when comparing the amount of reactive gas generated during positive charging and negative charging, it is known that the amount of generation of negative charging is overwhelmingly larger. It is understood that the phenomenon of image blur is caused at least by a decrease in the surface resistance of the photoconductor, and this decrease in surface resistance is caused by adhesion of a low resistance substance generated by a reactive gas to the surface of the photoconductor. It is also known to be the main cause.
[0027]
In order to improve such a point, a contact-type charging method has also been proposed. Although positive data is disclosed that the ozone concentration in the vicinity of the charging member is certainly low, the present inventors have disclosed. According to the measurement results, it has been clarified that the amount of the low-resistance substance adhering to the surface of the photoconductor is almost the same as that when a non-contact type charging member is used. This is because, by using a contact-type charging member, the voltage applied to the charging member can be lowered, but the distance to the photosensitive member for discharge is narrowed, and the air current does not flow well or is a low resistance material because it is in contact. This could be caused by pressing directly onto the surface of the photoreceptor.
[0028]
In view of the above points, when providing a surface layer for imparting abrasion resistance to a negatively charged photoreceptor, it is essential to use a filler having a large specific resistance, and inorganic photosensitive materials disclosed in the past are essential. It was found that the protective layer used on the body essentially needs to be changed.
[0029]
As described above, as a result of further studies based on the results obtained in the past, the following has become clear.
[0030]
<1> When the filler concentration in the surface layer (protective layer) is constant, the residual potential depends on the surface layer thickness and is proportional to the square of the film thickness.
[0031]
<2> When the surface layer thickness is constant, the residual potential depends on the filler concentration, and the residual potential increases as the filler concentration increases.
[0032]
<3> When the surface layer thickness is constant, the wear resistance depends on the filler concentration, and the wear resistance is improved as the filler concentration increases.
[0033]
<4> If the wear resistance is too large, image blur tends to occur.
[0034]
Therefore, there is a tendency for a trade-off relationship between improving wear resistance, reducing residual potential, improving wear resistance, and suppressing image blur. Therefore, as a result of repeated investigations in the direction of improving the layer structure of the surface layer, the present inventors have (i) a structure in which the surface layer is provided with a gradient of filler concentration (a structure in which the surface layer is gradually increased from the support side to the surface side). Or (ii) The above two problems can be cleared at the same time by (ii) making the surface layer a multi-layer structure of two or more layers having different filler concentrations and gradually increasing from the support side to the surface side. An electrophotographic method and an electrophotographic apparatus capable of designing a photoconductor capable of forming a high-quality image that is durable and stable for repeated use, and that can form a stable high-quality image at high speed even during repeated use. As a result, it has been found that an electrophotographic process cartridge can be designed, and the present invention has been completed. Further, in the tandem type full-color image forming apparatus using a plurality of image forming elements by using the photoconductor having the above-described configuration, the change in electrostatic characteristics of the photoconductor between the plurality of image forming elements and the amount of wear can be reduced. It was found that a tandem-type full-color image forming apparatus with reduced variation and good color reproducibility even after repeated use can be designed.
[0035]
According to the present invention, the following (1) to (16) are provided.
[0036]
(1) In an electrophotographic photoreceptor comprising a conductive layer and a photosensitive layer containing at least an organic charge generating substance and an organic charge transporting substance and a surface layer, the surface layer has a specific resistance of 10 ¹⁰ An electrophotographic photosensitive member comprising a filler having a density of Ω · cm or more and having a concentration gradient in which the filler concentration continuously increases from the support side to the surface side.
[0037]
(2) In an electrophotographic photosensitive member in which a photosensitive layer containing at least an organic charge generating substance and an organic charge transporting substance and a surface layer are provided on a conductive support, the surface layer is composed of two or more layers. , Specific resistance 10 for each surface layer ¹⁰ An electrophotographic photosensitive member comprising a filler of Ω · cm or more and having a structure in which the filler concentration gradually increases from the support side to the surface side.
[0038]
(3) The electrophotography as described in (1) or (2) above, wherein the filler concentration at the outermost surface of the surface layer is 5 to 40% by weight with respect to all materials constituting the surface layer. Photoconductor.
[0039]
(4) The filler contained in the surface layer has a specific resistance of 10 ¹⁰ The electrophotographic photosensitive member according to any one of the above (1) to (3), wherein the electrophotographic photosensitive member is an inorganic pigment of Ω · cm or more.
[0040]
(5) The inorganic pigment has a specific resistance of 10 ¹⁰ The electrophotographic photosensitive member as described in (4) above, which is a metal oxide of Ω · cm or more.
[0041]
(6) The metal oxide is selected from silica, alumina, and titanium oxide, and has a specific resistance of 10 ¹⁰ The electrophotographic photosensitive member as described in (5) above, which is Ω · cm or more.
[0042]
(7) The electrophotographic photosensitive member according to any one of (1) to (6) above, wherein the surface layer contains a charge transport material.
[0043]
(8) In the method for producing a surface layer of a photoreceptor according to any one of (1) and (3) to (7), a liquid having a low filler concentration using two or more kinds of coating solutions having different filler concentrations. A method for producing an electrophotographic photosensitive member, wherein the following coating solution is applied and laminated before the coating film applied one by one is touch-dried in this order by the spray method.
[0044]
(9) In the method for producing a surface layer of a photoreceptor according to any one of (2) to (7), two or more types of coating solutions having different filler concentrations are used, and a spray method is sequentially performed from a solution having a lower filler concentration. A method for producing an electrophotographic photosensitive member, comprising: applying the next coating solution after the coating film previously applied is finished with finger touch drying and then laminating.
[0045]
(10) In an electrophotographic method in which at least charging, image exposure, development, and transfer are repeatedly performed on an electrophotographic photosensitive member, the electrophotographic photosensitive member according to any one of (1) to (7) above An electrophotographic method characterized by the above.
[0046]
(11) 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 any one of the above (1) to (7) An electrophotographic apparatus according to the above item.
[0047]
(12) The electrophotographic apparatus as described in (11) above, wherein the charging means comprises a charging member in contact with or close to the photosensitive member.
[0048]
(13) The electrophotographic apparatus according to (12), wherein a gap between the charging member and the photosensitive member is 200 μm or less.
[0049]
(14) The electrophotography according to any one of (11) to (13), wherein the charging means superimposes an alternating current component on a direct current component on a charging member to charge the photosensitive member. apparatus.
[0050]
(15) A full-color electrophotographic apparatus in which a plurality of image forming elements each including at least an electrophotographic photosensitive member, a charging unit, an image exposing unit, a developing unit, and a transferring unit are arranged. A full-color electrophotographic apparatus which is the electrophotographic photosensitive member according to any one of (1) to (7).
[0051]
(16) A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of (1) to (7) above. A process cartridge for an electrophotographic apparatus.
[0052]
More preferable embodiments of the electrophotographic photosensitive member, the electrophotographic method, and the electrophotographic apparatus are as follows.
[0053]
(A) The photosensitive layer of the electrophotographic photosensitive member has a laminated structure of a charge generating layer containing at least an organic charge generating material and a charge transporting layer containing an organic charge transporting material. The organic charge generating substance is an azo pigment or a phthalocyanine pigment.
[0054]
(B) The inorganic pigment or metal oxide contained in the surface layer of the electrophotographic photosensitive member in the previous period has a pH of 5 or higher and / or a dielectric constant of 5 or higher.
[0055]
(C) The inorganic pigment or metal oxide is subjected to a surface treatment with at least one surface treatment agent. This surface treatment agent is titanate coupling agent, aluminum coupling agent, higher fatty acid, Al ₂ O ₃ TiO ₂ , ZrO ₂ 1 type chosen from any of these, or those mixtures, or a mixture of them and a silane coupling agent. In the inorganic pigment or metal oxide subjected to the surface treatment, the surface treatment amount is 3 to 30 wt%.
[0056]
(D) The average primary particle size of the filler contained in the outermost surface layer of the electrophotographic photosensitive member is 0.01 μm to 0.5 μm.
[0057]
(E) The charge transport material contained in the surface layer of the electrophotographic photosensitive member is a polymer charge transport material. The polymer charge transport material is a polycarbonate containing at least a triarylamine structure in the main chain and / or side chain. The charge transport material contained in the surface layer is the same as the charge transport material contained in the photosensitive layer or charge transport layer formed as a lower layer of the surface layer.
[0058]
(F) The binder resin contained in the surface layer of the electrophotographic photosensitive member contains at least one of a polycarbonate resin or a polyarylate resin.
[0059]
(G) In the method for producing the electrophotographic photosensitive member, the number of coating liquids to be used is continuously applied using a spray head.
[0060]
(H) In the electrophotographic method, a so-called digital electrophotographic method in which an electrostatic latent image is written on a photoreceptor by an LD or an LED at the time of image exposure is adopted.
[0061]
(I) The electrophotographic apparatus employs a so-called digital electrophotographic apparatus in which an electrostatic latent image is written on a photosensitive member by using an LD or LED as an image exposure means.
[0062]
DETAILED DESCRIPTION OF THE INVENTION
[0063]
Hereinafter, the electrophotographic photosensitive member used in the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration example of the electrophotographic photosensitive member of the present invention. On a conductive support 31, a single-layer photosensitive layer 33 mainly composed of a charge generating material and a charge transporting material is provided. Further, a surface layer 39 is provided on the surface of the photosensitive layer. In this case, the surface layer 39 contains a filler and has a configuration in which the filler concentration is continuously increased from the support side to the surface side (having a concentration gradient). The filler used here has a specific resistance of 10 ¹⁰ Ω · cm or more.
[0064]
FIG. 2 is a cross-sectional view showing another configuration example of the electrophotographic photosensitive member of the present invention. On the conductive support 31, a charge generation layer 35 mainly composed of a charge generation material and a charge transport material as a main component. The charge transport layer 37 is laminated, and a surface layer 39 is further provided on the charge transport layer. In this case, the surface layer 39 contains a filler and has a configuration in which the filler concentration is continuously increased from the support side to the surface side (having a concentration gradient). The filler used here has a specific resistance of 10 ¹⁰ Ω · cm or more.
[0065]
FIG. 3 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member of the present invention. A single-layer photosensitive layer 33 mainly composed of a charge generating material and a charge transporting material is provided on a conductive support 31. Furthermore, a plurality of surface layers 39 (for example, surface layers composed of 39-1, 39-2, 39-3) having different filler concentrations are provided on the surface of the photosensitive layer. In this case, the plurality of surface layers 39 have a specific resistance of 10 ¹⁰ The filler contains a filler of Ω · cm or more, and the filler concentration is gradually increased from the support side to the surface side.
[0066]
FIG. 4 is a cross-sectional view showing still another structural example of the electrophotographic photosensitive member of the present invention. The charge generation layer 35 mainly composed of the charge generation material and the charge transport material are mainly formed on the conductive support 31. A charge transport layer 37 as a component is laminated, and a surface layer 39 having different filler concentrations (for example, a surface comprising 39-1, 39-2, 39-3) on the charge transport layer. Layer). In this case, the plurality of surface layers 39 have a specific resistance of 10 ¹⁰ The filler contains a filler of Ω · cm or more, and the filler concentration is gradually increased from the support side to the surface side.
[0067]
1 to 4 described above, the filler used may be a mixture of two or more fillers. In such a case, it may be composed of the same material (material) or different materials. When it is not desired to greatly change the characteristics as the bulk of the protective layer, stable characteristics can be obtained by using the same material. On the other hand, when you want to adjust the resistance of the protective layer bulk, or when you want to control the transmittance in the bulk direction, you can mix two or more fillers with different specific resistances, or the particle size distribution (average particle size) Two or more different fillers may be mixed and used. In such a case, if a component having a small resistance is included on the surface side, a side effect may occur that the occurrence of image blur tends to occur. For this reason, it is effective to use a high resistance filler on the surface side and a low resistance filler on the support (photosensitive layer) side. Further, when a filler having a small particle diameter is used on the surface side, side effects such as a decrease in wear resistance may occur. For this reason, it is effective to use a filler having a large particle diameter on the surface side and a filler having a small particle diameter on the photosensitive layer side. Thus, adding the gradient of resistivity and the gradient of particle size at the same time as forming the gradient of the filler concentration distribution makes the effects of the present invention more remarkable.
[0068]
The conductive support 31 has a volume resistance of 10 ¹⁰ 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 or an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can also be used as the conductive support 31.
[0069]
Of these, a cylindrical support made of aluminum that can be easily subjected to the anodic oxide film treatment can be most preferably used. As used herein, aluminum includes both pure aluminum and aluminum alloys. Specifically, JIS 1000, 3000, and 6000 series aluminum or aluminum alloy is most suitable. The anodized film is obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or an aluminum alloy that has been anodized in an electrolyte solution is used in the present invention. Is most suitable for. In particular, it is excellent in preventing point defects (black spots, background stains) that occur when used in reversal development (negative / positive development).
[0070]
The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example,
Sulfuric acid concentration: 10-20%,
Bath temperature: 5-25 ° C.
Current density: 1-4 A / dm ² ,
Electrolytic voltage: 5-30V,
Processing time: about 5-60 minutes
However, the present invention is not limited to this.
[0071]
Since the anodic oxide film produced in this way is porous and has high insulation, the surface is very unstable. For this reason, there is a change with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is desirable to further seal the anodized film.
[0072]
Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable.
[0073]
Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains excessively on the surface of the support (anodized film), it will not only adversely affect the quality of the coating film formed on it, but also generally a low resistance component will remain. It can also be a cause.
[0074]
The cleaning may be performed once with pure water, but is usually performed at another stage. At this time, it is preferable that the final cleaning liquid is as clean (deionized) as possible. Moreover, it is desirable to perform physical rubbing cleaning with a contact member in one of the other cleaning processes.
[0075]
The film thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is too thin, the effect of the barrier property as an anodic oxide film is not sufficient, and if it is thicker than this, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.
[0076]
In addition, the conductive support 31 of the present invention can be used by dispersing conductive powder in an appropriate binder resin and coating the support. 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-vinyl carbazole, 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.
[0077]
Furthermore, a conductive layer is formed on a suitable cylindrical substrate by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or fluororesin. What is provided can also be used favorably as the conductive support 31 of the present invention.
[0078]
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 it is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.
[0079]
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 monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinone condensed polycycles. Examples thereof include compounds, squalic acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, and azulenium salt dyes. These charge generation materials may be used alone or in combination of two or more.
[0080]
Of these, azo pigments and / or phthalocyanine pigments are effectively used. In particular, at least 27.2 as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to characteristic X-rays (wavelength 1.542 mm) of azo pigments represented by the following structural formula (I) and titanyl phthalocyanine, particularly CuKα. Titanyl phthalocyanine having a maximum diffraction peak at 0 ° can be used effectively.
[0081]
[Chemical 1]

Where Cp ₁ , Cp ₂ Represents a coupler residue and may be the same or different. R ₂₀₁ , R ₂₀₂ Each represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, which may be the same or different. Cp ₁ , Cp ₂ Is represented by the following formula (II):
[0082]
[Chemical 2]

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 each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, an alkyl group such as a trifluoromethyl group, a methyl group or an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, or a dialkyl An amino group and a hydroxyl group are represented, and Z represents an atomic group necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring.
[0083]
In particular, the asymmetric azo pigment having a structure in which Cp1 and Cp2 are different from each other often has better photosensitivity than the target azo pigment having the same structure in Cp1 and Cp2. Can be used effectively, and is used effectively.
[0084]
Among the titanyl phthalocyanines having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ, titanyl phthalocyanine having a peak at 7.3 ° as a minimum angle (Japanese Patent Laid-Open No. 2001-19871). Is described in Japanese Patent Publication No. JP-A No. 1993-133, and has high sensitivity and a small decrease in chargeability in repeated use, and can be used particularly effectively.
[0085]
The charge generation layer 35 is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is applied onto a conductive support and dried. It is formed.
[0086]
As the binder resin used for the charge generation layer 35 as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N -Vinylcarbazole, 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. Can be mentioned. 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.
[0087]
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, and ligroin. In particular, ketone solvents, ester solvents, and ether solvents are preferably used. 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 thickness of the charge generation layer 35 is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.
[0088]
The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
[0089]
Charge transport materials include hole transport materials and electron transport materials. Examples of the charge transport material include chloroanil, bromanyl, 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.
[0090]
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, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.
[0091]
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, polyarate, 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 Examples thereof include thermoplastic or thermosetting resins such as resins and alkyd resins.
[0092]
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. Regarding the lower limit, although it differs depending on the system to be used (particularly the charging potential), 5 μm or more is preferable.
[0093]
Examples of the solvent used here include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, and acetone.
[0094]
In the photoreceptor of the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37. As the plasticizer, those used as general plasticizers such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used 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 methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.
[0095]
Next, the case where the photosensitive layer has a single layer structure 33 will be described. A photoreceptor in which the above-described charge generating material 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 them. Further, the photosensitive layer may be a function separation type to which the above-described charge transport material is added, and can be used satisfactorily. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
[0096]
As the binder resin, the binder resin previously mentioned in the charge transport layer 37 may be used as it is, or the binder resin mentioned in the charge generation layer 35 may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. 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.
[0097]
A single-layer photosensitive layer is formed by dip coating or spraying with a coating solution dispersed with a disperser using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane together with a charge transport material, if necessary, with a charge generating material and a binder resin. It can be formed by coating with a coat or bead coat. The film thickness of the single photosensitive layer is suitably about 5 to 25 μm.
[0098]
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.
[0099]
These undercoat layers can be formed using an appropriate solvent and coating method as in 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 ₃ 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 also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0100]
In the photoreceptor of the present invention, the surface layer 39 is provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The surface layer 39 is configured such that the filler concentration continuously increases from the support side to the surface side (FIGS. 1 and 2). Or the surface layer 39 is comprised from several layers from which a filler density | concentration differs (FIG. 3, FIG. 4), and is comprised so that a filler density | concentration may become high sequentially toward a surface side from a support body side in this case. As a result, it is possible to improve both the wear resistance of the surface and reduce the residual potential.
[0101]
The filler concentration in the surface layer varies depending on the type of filler used and the electrophotographic process conditions using the photoreceptor, but in the outermost layer side or the outermost layer side layer, the ratio of filler to the total solid content is 40 wt. % Or less, preferably 30% by weight or less, 5% by weight or more, and preferably about 10% by weight or more. In the layer on the most photosensitive layer side, 30% by weight or less, preferably about 10% by weight or less is good. When the filler concentration at the outermost surface of the surface layer is 5% by weight or less, wear resistance cannot be obtained, and the variation in film thickness due to wear due to repeated use increases. On the other hand, if it is 40% by weight or more, the increase in the residual potential due to repeated use increases, the surface properties become rough, and the scattering of writing light increases.
[0102]
Materials used for the surface layer 39 are ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene. , Polybutylene terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, poly Examples thereof include resins such as vinyl chloride, polyvinylidene chloride, and epoxy resin. Of these, polycarbonate or polyarylate can be most preferably used.
[0103]
In addition, a filler material is added to the surface layer of the photoreceptor for the purpose of improving wear resistance. Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, etc., and inorganic filler material includes metal powder such as copper, tin, aluminum, indium, Examples thereof include inorganic materials such as silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, metal oxide such as indium oxide doped with tin, and potassium titanate. In particular, it is advantageous to use an inorganic material from the viewpoint of the hardness of the filler. In particular, silica, titanium oxide, and alumina can be used effectively.
[0104]
Furthermore, as a filler that hardly causes image blur, a filler having high electrical insulation (specific resistance is 10%). ¹⁰ (Ω · cm or more) is preferable, and those having a filler pH of 5 or more and those having a dielectric constant of 5 or more can be used particularly effectively. In addition, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more can be used alone, or two or more fillers having a pH of 5 or less and a filler having a pH of 5 or more can be mixed. It is also possible to mix two or more fillers having a dielectric constant of 5 or less and fillers having a dielectric constant of 5 or more. Among these fillers, α-type alumina, which has high insulation properties, high thermal stability, and high wear resistance, is a hexagonal close-packed structure, from the viewpoint of suppressing image blur and improving wear resistance. It is particularly useful.
[0105]
The specific resistance of the filler used in the present invention is defined as follows. Since the specific resistance value of the powder such as the filler varies depending on the filling rate, it is necessary to measure under a certain condition. In the present invention, the specific resistance value of the filler is determined using an apparatus having the same configuration as the measuring apparatus shown in Japanese Patent Laid-Open Nos. 5-94049 (FIG. 1) and 5-113688 (FIG. 1). Measured and used this value. In the measuring device, the electrode area is 4.0 cm. ² It is. Prior to measurement, a load of 4 kg is applied to one electrode for 1 minute, and the sample amount is adjusted so that the distance between the electrodes is 4 mm. At the time of measurement, the measurement is performed with the upper electrode weight (1 kg) loaded, and the applied voltage is measured at 100V. 10 ⁶ The region above Ω · cm was measured with HIGH RESISTING METER (Yokogawa Hewlett Packard), and the region below it was measured with a digital multimeter (Fluk). The specific resistance value obtained in this way is defined as the specific resistance value according to the present invention.
[0106]
Further, the pH of the filler, which is one of the constituent requirements of the present invention, greatly affects the resolution and the dispersibility of the filler. One possible reason is that hydrochloric acid or the like remains in the filler, particularly the metal oxide, during production. When the remaining amount is large, the occurrence of image blur is unavoidable, and depending on the remaining amount, the dispersibility of the filler may be affected. Another reason is due to the difference in chargeability on the surface of the filler, particularly the metal oxide. Normally, particles dispersed in a liquid are charged positively or negatively, and ions having opposite charges gather to try to keep it electrically neutral, and an electric double layer is formed there. The dispersed state of the particles is stabilized. The potential (zeta potential) gradually decreases as the distance from the particle increases, and the potential of a region that is sufficiently away from the particle and electrically neutral is zero. Accordingly, the stability increases as the repulsive force of the particles increases due to the increase in the absolute value of the zeta potential, and the particles tend to aggregate and become unstable as they approach zero. On the other hand, the zeta potential varies greatly depending on the pH value of the system, and at a certain pH value, the potential becomes zero and has an isoelectric point. Therefore, the dispersion system is stabilized by increasing the absolute value of the zeta potential as far as possible from the isoelectric point of the system.
[0107]
In the configuration of the present invention, the filler having a pH at the isoelectric point of at least 5 is preferably from the viewpoint of image blur suppression, and the more basic the filler, the higher the effect. It was confirmed that there was. The filler having a high basic pH at the isoelectric point has a higher zeta potential when the system is acidic, so that dispersibility and stability thereof are improved. Here, the pH of the filler in the present invention is the pH value at the isoelectric point from the zeta potential. At this time, the zeta potential was measured with a laser zeta potentiometer manufactured by Otsuka Electronics Co., Ltd. The dielectric constant of the filler was measured as follows. Using a cell similar to the measurement of the specific resistance as described above, after applying a load, the capacitance was measured, and the dielectric constant was determined from this. For the measurement of the capacitance, a dielectric loss measuring device (manufactured by Ando Electric Co., Ltd.) was used.
[0108]
Further, these fillers can be surface-treated with at least one kind of surface treatment agent, and it is preferable from the viewpoint of dispersibility of the fillers. 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 ₃ 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.
[0109]
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. These filler materials may be used alone or in combination of two or more. The surface treatment amount of the filler is defined by the weight ratio of the surface treatment agent to be used with respect to the filler amount as described above.
[0110]
These filler materials can be dispersed by using an appropriate disperser. The average particle size of the filler is preferably 1 μm or less, and more preferably 0.5 μm or less from the viewpoint of the transmittance of the surface layer. The average particle size of the filler in the present invention is a volume average particle size unless otherwise specified, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba). At this time, the particle size (Median system) corresponding to 50% of the cumulative distribution was calculated. In addition, it is important that the standard deviation of each particle measured simultaneously is 1 μm or less. If the standard deviation is larger than this, the particle size distribution may be too wide, and the effects of the present invention may not be obtained remarkably.
[0111]
The thickness of the surface layer is suitably about 0.1 to 10 μm in total of the plurality of layers.
[0112]
As a method for forming the surface layer of the present invention, a normal coating method is employed. Among them, the spray method is an effective means. A method of laminating multiple surface layer coating solutions with different filler concentrations by the spray method before the lower layer is touch-dried, or a method of laminating by the spray method after the lower layer is dried by touch Is the most suitable. In this case, it is desirable to prepare as many spray heads as the number of coating liquids and perform coating continuously.
[0113]
Further, the surface layer 39 may contain a charge transport material for reducing residual potential and improving responsiveness. As the charge transport material, the materials described in the description of the charge transport layer can be used. When a low molecular charge transport material is used as the charge transport material, the concentration in the plurality of surface layers may be changed. In order to improve wear resistance, it is an effective means to reduce the concentration of the surface side. The concentration here refers to the ratio of the weight of the low-molecular charge transporting substance to the total weight of all the materials constituting the surface layer, and the concentration gradient is a gradient that lowers the concentration on the surface side in the above weight ratio. It shows that.
[0114]
In addition, the charge transport material used for the surface layer may be a low molecular charge transport material as described above or a polymer charge transport material as described below. However, the photosensitive layer or the charge transport layer formed as a lower layer of the surface layer. It is preferable to use the same charge transport material as used in the above. This is because when photocarriers formed in the photosensitive layer are transported to the surface of the photoreceptor, charges are transferred from the photosensitive layer (charge transport layer) to the surface layer, but in the case of the same structure, an energy gap (barrier), etc. This is because the smooth charge transfer is performed without forming the.
[0115]
In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the surface layer. The surface layer composed of these polymer charge transport materials is excellent in wear resistance. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, the polymer charge transport materials represented by the formulas (III) to (XII) are favorably used, and these are exemplified below and specific examples are shown.
[0116]
(III) Formula
[0117]
[Chemical 3]

Where R ₁ , R ₂ , R ₃ Each independently represents a substituted or unsubstituted alkyl group or a halogen atom, R4 represents a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ , R6 is a substituted or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9 , 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.
[0118]
[Formula 4]

Where R ₁₀₁ , R ₁₀₂ Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 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
[0119]
[Chemical formula 5]

(Wherein, 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.
[0120]
(IV) Formula
[0121]
[Chemical 6]

Where R ₇ , R ₈ Is a substituted or unsubstituted aryl group, Ar _1, Ar ₂ , Ar ₃ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0122]
(V) Formula
[0123]
[Chemical 7]

Where R ₉ , R ₁₀ Is a substituted or unsubstituted aryl group, Ar ₄ , Ar ₅ , Ar ₆ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0124]
Formula (VI)
[0125]
[Chemical 8]

Where R ₁₁ , R ₁₂ Is a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , Ar ₉ Are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as those in the formula (III).
[0126]
(VII) Formula
[0127]
[Chemical 9]

Where R ₁₃ , 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 formula (III).
[0128]
(VIII) Formula
[0129]
[Chemical Formula 10]

Where R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ Is a substituted or unsubstituted aryl group, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , 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, or a vinylene group, which may be the same or different. X, k, j and n are the same as those in the formula (III).
[0130]
(IX) Formula
[0131]
Embedded image

Where R ₁₉ , R ₂₀ Represents a hydrogen atom, a substituted or unsubstituted aryl group, and R ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0132]
(X) Formula
[0133]
Embedded image

Where R ₂₁ Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , Ar ₂₃ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0134]
(XI) Formula
[0135]
Embedded image

Where R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ Is a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₅ , Ar ₂₇ , Ar ₂₈ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0136]
(XII) Formula
[0137]
Embedded image

Where R ₂₆ , R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ , Ar ₃₁ Represent the same or different arylene groups. X, k, j and n are the same as those in the formula (III).
[0138]
In addition to the polymer charge transport material described above, the polymer charge transport material used in the protective layer is a monomer or oligomer having an electron-donating group at the time of film formation of the protective layer. Or the polymer which finally has a two-dimensional or three-dimensional crosslinked structure is also included by carrying out a crosslinking reaction.
[0139]
A protective layer composed of a polymer having these electron donating groups or a polymer having a crosslinked structure is excellent in wear resistance. Usually, in the electrophotographic process, since the charged potential (unexposed portion potential) is constant, if the surface layer of the photoconductor is worn by repeated use, the electric field strength applied to the photoconductor increases accordingly. As the electric field strength increases, the occurrence frequency of scumming increases. Therefore, the high wear resistance of the photosensitive member is advantageous for scumming. The protective layer composed of a polymer having these electron-donating groups is a polymer compound, so it has excellent film-forming properties and has a higher density of charge transport sites than a protective layer composed of a low molecular dispersion type polymer. It is possible to form the structure and has excellent charge transport ability. For this reason, a photoreceptor having a protective layer using a polymer charge transport material can be expected to have a high response speed.
[0140]
Examples of the other polymer having an electron donating group include a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, and for example, JP-A-3-109406, JP-A 20000- It is also possible to use a cross-linked polymer having an electron donating group as disclosed in JP-A-206723 and JP-A No. 2001-34001.
[0141]
In the photoreceptor of the present invention, a binder resin is generally used as a main component in the intermediate layer in which an intermediate layer can be provided between the photosensitive layer and the protective layer. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.
[0142]
In the present invention, in order to improve environmental resistance, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, an antioxidant, a plasticizer, a lubricant, an ultraviolet absorber, and a low molecular charge transport material are used for each layer. And leveling agents can be added. Representative materials of these compounds are described below.
[0143]
Examples of the antioxidant that can be added to each layer include, but are not limited to, the following.
[0144]
(A) Phenolic compounds
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4′-hydroxy-3) ', 5'-di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6) -T-butylphenol), 4,4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t- Butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-tert-butylphenyl) butyric assy Do] Cricol ester, tocopherols and the like.
[0145]
(B) Paraphenylenediamines
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
[0146]
(C) Hydroquinones
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.
[0147]
(D) Organic sulfur compounds
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate and the like.
[0148]
(E) Organophosphorus compounds
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
[0149]
Examples of the plasticizer that can be added to each layer include, but are not limited to, the following.
[0150]
(A) Phosphate ester plasticizer
Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate and the like.
[0151]
(B) Phthalate ester plasticizer
Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, dinonyl phthalate, diisononyl phthalate, phthalic acid Diisodecyl, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate, etc.
[0152]
(C) Aromatic carboxylic ester plasticizer
Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.
[0153]
(D) Aliphatic dibasic acid ester plasticizer
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl-n-decyl adipate, diisodecyl adipate, dicapryl adipate, diazeline 2-ethylhexyl, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, Dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.
[0154]
(E) Fatty acid ester derivatives
Butyl oleate, glycerol monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
[0155]
(F) Oxyester plasticizer
Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.
[0156]
(G) Epoxy plasticizer
Epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate and the like.
[0157]
(H) Dihydric alcohol ester plasticizer
Diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate, etc.
[0158]
(I) Chlorine-containing plasticizer
Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, etc.
[0159]
(J) Polyester plasticizer
Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, etc.
[0160]
(K) Sulfonic acid derivative
p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide and the like.
[0161]
(L) Citric acid derivative
Triethyl citrate, triethyl citrate citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, acetyl citrate-n-octyldecyl and the like.
[0162]
(M) Other
Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.
[0163]
Examples of the lubricant that can be added to each layer include, but are not limited to, the following.
[0164]
(A) Hydrocarbon compounds
Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, etc.
[0165]
(B) Fatty acid compounds
Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, etc.
[0166]
(C) Fatty acid amide compounds
Stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide, etc.
[0167]
(D) Ester compound
Lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, fatty acid polyglycol esters, and the like.
[0168]
(E) Alcohol compounds
Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol, etc.
[0169]
(F) Metal soap
Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate, etc.
[0170]
(G) Natural wax
Carnauba wax, candelilla wax, beeswax, whale wax, ibotarou, montanro, etc.
[0171]
(H) Other
Silicone compounds, fluorine compounds, etc.
[0172]
Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
[0173]
(A) Benzophenone series
2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like.
[0174]
(B) Salsylate type
Phenyl salicylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl-4-hydroxybenzoate, and the like.
[0175]
(C) Benzotriazole type
(2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3′-tertiarybutyl 5) '-Methylphenyl) 5-chlorobenzotriazole
[0176]
(D) Cyanoacrylate type
Ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, and the like.
[0177]
(E) Quencher (metal complex)
Nickel (2,2′thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.
[0178]
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- 2,2,6,6-tetramethylpiperidine and the like.
[0179]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings. FIG. 5 is a schematic diagram for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention. In FIG. 5, the photoreceptor 1 is formed by providing at least a photosensitive layer and a surface layer having a filler concentration gradient or a surface layer composed of a plurality of layers having different filler concentrations on a conductive support. The photosensitive member 1 has a drum shape, but may be a sheet shape or an endless belt shape. For the charging member 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. It is done. The charging member 3 is preferably used in contact with or close to the photoreceptor 1.
[0180]
The contact-type charging member here is a type in which the surface of the charging member is in contact with the surface of the photosensitive member, and includes a charging roller, a charging blade, and a charging brush. Among them, a charging roller and a charging brush are used favorably. Further, the charging member arranged in the proximity is a type in which the charging member is arranged in a non-contact state so as to have a gap (gap) of 200 μm or less between the surface of the photoreceptor and the charging member. It is distinguished from known chargers typified by corotron and scorotron from the distance of the gap. The adjacently arranged charging member used in the present invention may have any shape as long as it has a mechanism capable of appropriately controlling the gap with the surface of the photoreceptor. For example, the rotation shaft of the photosensitive member and the rotation shaft of the charging member may be mechanically fixed so as to have an appropriate gap. Among them, using a charging member in the shape of a charging roller, a gap forming member is disposed at both ends of the non-image forming portion of the charging member, and only this portion is brought into contact with the surface of the photoreceptor, and the image forming region is disposed in a non-contact manner. Alternatively, the gap forming member at both ends of the non-photosensitive portion of the photoconductor is disposed, and only this portion is brought into contact with the surface of the charging member, and the image forming region is disposed in a non-contact manner, so that the gap can be stably stabilized. It is a method that can be maintained. In particular, the methods described in Japanese Patent Application Nos. 13-21448 and 13-226432 can be used satisfactorily. An example of the proximity charging mechanism in which the gap forming member is arranged on the charging member side is shown in FIG.
[0181]
In addition, when charging the photosensitive member with the charging member, charging unevenness can be effectively reduced by charging the photosensitive member with an electric field in which an AC component is superimposed on a DC component on the charging member.
[0182]
As the transfer means, the above charger can be generally used, but a combination of the transfer charger 10 and the separation charger 11 as shown in FIG. 5 is effective.
[0183]
In addition, light sources such as the image exposure unit 5 and the charge removal lamp 2 emit light such as 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). All things 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. Such a light source or the like irradiates the photosensitive member with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG.
[0184]
The toner developed on the photosensitive member 1 by the developing unit 6 is transferred to the transfer paper 9, but not all is transferred, and some toner remains on the photosensitive member 1. 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.
[0185]
When the electrophotographic photosensitive member is positively (negatively) charged 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.
[0186]
FIG. 6 shows another example of the electrophotographic process according to the present invention. The photoreceptor 21 is formed by providing at least a photosensitive layer and a surface layer having a filler concentration gradient or a surface layer composed of a plurality of layers having different filler concentrations on a conductive support. Driven by driving rollers 22a and 22b, charging by charger 23, image exposure by light source 24, development (not shown), transfer using charger 25, exposure before cleaning by light source 26, cleaning by brush 27, by light source 28 Static elimination is repeated. In FIG. 6, the photoconductor 21 (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.
[0187]
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. 6, the pre-cleaning exposure is performed from the support side, but this may be performed from the surface 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.
[0188]
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. The photoreceptor 23 is formed by providing at least a photosensitive layer and a surface layer having a gradient of filler concentration or a surface layer composed of a plurality of layers having different filler concentrations on a conductive support.
[0189]
FIG. 10 is a schematic diagram for explaining the tandem-type full-color electrophotographic apparatus of the present invention, and modifications as described below also belong to the category of the present invention. In FIG. 10, reference numerals 1C, 1M, 1Y, and 1K denote drum-shaped photoconductors. The photoconductors 1C, 1M, 1Y, and 1K rotate in the direction of the arrow in the figure, and at least around the charging member 2C in the order of rotation. 2M, 2Y, 2K, developing members 4C, 4M, 4Y, 4K, and cleaning members 5C, 5M, 5Y, 5K are arranged. The charging members 2C, 2M, 2Y, and 2K are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor. Laser beams 3C, 3M, 3Y, and 3K from an exposure member (not shown) are irradiated on the surface of the photosensitive member between the charging members 2C, 2M, 2Y, and 2K and the developing members 4C, 4M, 4Y, and 4K. Electrostatic latent images are formed at 1M, 1Y, and 1K. The four image forming elements 6C, 6M, 6Y, and 6K centering on the photoreceptors 1C, 1M, 1Y, and 1K are juxtaposed along the transfer conveyance belt 10 that is a transfer material conveyance unit. The transfer conveyance belt 10 contacts the photoreceptors 1C, 1M, 1Y, and 1K between the developing members 4C, 4M, 4Y, and 4K and the cleaning members 5C, 5M, 5Y, and 5K of the image forming units 6C, 6M, 6Y, and 6K. Transfer brushes 11 </ b> C, 11 </ b> M, 11 </ b> Y, and 11 </ b> K for applying a transfer bias are disposed on a surface (back surface) that is in contact with the back side of the transfer conveyance belt 10 on the photoconductor side. Each of the image forming elements 6C, 6M, 6Y, and 6K is different in toner color in the developing device, and only the DC component is applied to the black toner image forming charging member 2K according to the present invention. An alternating electric field in which an AC component is superimposed on a DC component is applied to the charging members 2C, 2M, and 2Y, and the rest of the configuration is the same.
[0190]
In the color electrophotographic apparatus having the configuration shown in FIG. 10, the image forming operation is performed as follows. First, in each of the image forming elements 6C, 6M, 6Y, and 6K, the photoreceptors 1C, 1M, 1Y, and 1K are charged by charging members 2C, 2M, 2Y, and 2K that rotate in the direction of the arrow (the direction along with the photoreceptor). Next, an electrostatic latent image corresponding to each color image to be created is formed by the laser beams 3C, 3M, 3Y, and 3K in the exposure unit. Next, the latent image is developed by developing members 4C, 4M, 4Y, and 4K to form a toner image. The developing members 4C, 4M, 4Y, and 4K are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and the four photosensitive members 1C, 1M, and 1Y. The toner images of each color created on 1K are superimposed on the transfer paper. The transfer paper 7 is sent out from the tray by a paper feed roller 8, temporarily stopped by a pair of registration rollers 9, and sent to the transfer conveyance belt 10 in synchronization with the image formation on the photosensitive member. The transfer paper 7 held on the transfer conveyance belt 10 is conveyed, and the color toner images are transferred at the contact positions (transfer portions) with the photoconductors 1C, 1M, 1Y, and 1K. The toner image on the photoconductor is transferred onto the transfer paper 7 by an electric field formed from a potential difference between the transfer bias applied to the transfer brushes 11C, 11M, 11Y, and 11K and the photoconductors 1C, 1M, 1Y, and 1K. The Then, the recording paper 7 on which the four color toner images are passed through the four transfer portions is conveyed to the fixing device 12, where the toner is fixed, and is discharged to a paper discharge portion (not shown). In addition, the residual toner that is not transferred by the transfer unit and remains on the photosensitive members 1C, 1M, 1Y, and 1K is collected by the cleaning devices 5C, 5M, 5Y, and 5K.
[0191]
In the example of FIG. 10, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when creating a black-only document, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (6C, 6M, 6Y) other than black. Further, in FIG. 10, the charging member is in contact with the photosensitive member, but by providing an appropriate gap (about 10 to 200 μm) between them, the wear amount of both can be reduced and the charging member can be applied to the charging member. Less toner filming and good use.
[0192]
The image forming means as described above may be fixedly incorporated in a copying apparatus, facsimile, or printer, but each electrophotographic element may be incorporated in the apparatus in the form of a process cartridge. A process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like.
[0193]
【Example】
[0194]
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.
[0195]
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 and dried on an aluminum cylinder to generate a 3.5 μm undercoat layer and a 0.2 μm charge generation. An electrophotographic photosensitive member comprising a layer, a 20 μm charge transport layer, and a 5 μm surface layer was formed. The undercoat layer, the charge generation layer, and the charge transport layer were applied by a dip coating method, and the surface layer was applied by a spray method.
[0196]
Undercoat layer coating solution:
400 parts of titanium dioxide powder
65 parts of melamine resin
120 parts alkyd resin
2-butanone 400 parts
[0197]
Charge generation layer coating solution:
12 parts of bisazo pigment with the following structure
[0198]
Embedded image

Polyvinyl butyral 2 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0199]
Charge transport layer coating solution:
10 parts of A type polycarbonate
8 parts of charge transport material of the following structural formula
[0200]
Embedded image

Tetrahydrofuran 200 parts
[0201]
Surface layer coating solution 1:
10 parts of C type polycarbonate
7 parts of charge transport material with the following structural formula
[0202]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0203]
Surface layer coating solution 2:
10 parts of C type polycarbonate
7 parts of charge transport material with the following structural formula
[0204]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 4 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0205]
Surface layer coating solution 3:
10 parts of C type polycarbonate
7 parts of charge transport material with the following structural formula
[0206]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 7 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0207]
The surface layer coating solution was continuously applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, the term “continuous” means that the next coating liquid is laminated by spraying after the lower layer is coated and before the touch is dried. The surface layer coating liquids 1 and 2 were applied in an amount corresponding to 2 μm, and the surface layer coating liquid 3 was applied in an amount corresponding to 1 μm to form a total surface layer of 5 μm.
[0208]
(Example 2)
A photoconductor was prepared in the same manner as in Example 1 except that the surface layer coating solutions 1, 2, and 3 in Example 1 were changed to those having the following compositions, respectively.
[0209]
Surface layer coating solution 1:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0210]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
Average primary particle size: 0.3 μm) 1 part
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0211]
Surface layer coating solution 2:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0212]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0213]
Surface layer coating solution 3:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0214]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 3 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0215]
(Comparative Example 1)
A photoreceptor was prepared in exactly the same manner as in Example 1, except that only the surface layer coating solution 1 was used as the surface layer in Example 1 and a surface layer corresponding to 5 μm was formed.
[0216]
(Comparative Example 2)
A photoconductor was produced in the same manner as in Example 1 except that only the surface layer coating solution 3 was used as the surface layer in Example 1 and a surface layer corresponding to 5 μm was formed.
[0217]
(Comparative Example 3)
A photoconductor was prepared in the same manner as in Example 1 except that the filler (alumina fine particles) contained in the surface layer coating liquids 1, 2, and 3 in Example 1 was changed to the following.
[0218]
Filler: Conductive tin oxide (specific resistance: 5 × 10 ⁵ (Ω · cm, average primary particle size: 0.3 μm)
[0219]
(Comparative Example 4)
A photoconductor was prepared in exactly the same manner as in Example 2, except that only the surface layer coating solution 1 was used as the surface layer in Example 2 and a surface layer corresponding to 5 μm was formed.
[0220]
(Comparative Example 5)
A photoconductor was prepared in exactly the same manner as in Example 2, except that only the surface layer coating solution 1 was used as the surface layer in Example 2 and a surface layer corresponding to 5 μm was formed.
[0221]
The photoconductors of Examples 1 and 2 and Comparative Examples 1 to 5 produced as described above were mounted on the electrophotographic process shown in FIG. 5 (however, there was no exposure before cleaning, and the charging member was a scorotron charger), and image exposure was performed. The light source was a semiconductor laser of 655 nm (image writing with a polygon mirror), and 20,000 sheets were printed continuously, and the images at that time were evaluated initially and after 20,000 sheets. In addition, the amount of wear on the surface of the photoreceptor on 20,000 sheets was also measured. The above results are also shown in Table 1.
[0222]
[Table 1]

[0223]
Example 3
The charging member of the electrophotographic process shown in FIG. 5 used in Example 1 was changed from the scorotron charger to the charging roller, and the charging roller was disposed so as to contact the photoreceptor. The photoconductor produced in Example 1 was mounted on this apparatus, and the same evaluation as in Example 1 was performed under the following charging conditions.
[0224]
Charging conditions:
DC bias: -930V
As a result, both the initial image and the 20,000th image were good, but the image after 20,000th image was found to have a very slight abnormal image (ground stain) based on the charging roller stain (toner filming). It was. However, the ozone odor during continuous printing was much less than that in Example 1.
[0225]
(Example 4)
An insulating tape having a thickness of 50 μm and a width of 5 mm was attached to both ends of the charging roller used in Example 3, and arranged so as to have a spatial gap (50 μm) between the charging roller surface and the photoreceptor surface. The other conditions were evaluated in the same manner as in Example 3. As a result, no charging roller contamination was observed in Example 3, and both the initial and 20,000th images were good. However, when a halftone image was output after 20,000 sheets, image unevenness based on charging unevenness was recognized although it was very slight.
[0226]
(Example 5)
In the evaluation of Example 4, the same evaluation as in Example 4 was performed except that the charging conditions were changed as follows.
[0227]
Charging conditions:
DC bias: -900V
AC bias: 2.0 kV (peak to peak), frequency 2 kHz
The initial image and the image after 20,000 sheets were good. The charging roller stains observed in Example 3 and the halftone image unevenness observed in Example 4 were not recognized at all.
[0228]
( Reference 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 and dried on a nickel belt, and a 3 μm undercoat layer, a 0.3 μm charge generation layer, An electrophotographic photosensitive member having a 22 μm charge transport layer and a 3 μm surface layer was formed. The undercoat layer, the charge generation layer, and the charge transport layer were applied by a dip coating method, and the surface layer was applied by a spray method.
[0229]
Undercoat layer coating solution:
100 parts of titanium dioxide powder
100 parts of alcohol-soluble nylon
500 parts of methanol
300 parts of butanol
[0230]
Charge generation layer coating solution:
10 parts of bisazo pigment with the following structure
[0231]
Embedded image

Polyvinyl butyral 2 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0232]
Charge transport layer coating solution:
10 parts of Z-type polycarbonate
7 parts of charge transport material with the following structural formula
[0233]
Embedded image

Tetrahydrofuran 200 parts
[0234]
Surface layer coating solution 1:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0235]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
(Average primary particle size: 0.3 μm) 1.5 parts
600 parts of toluene
[0236]
Surface layer coating solution 2:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0237]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
(Average primary particle size: 0.3 μm) 4 parts
600 parts of toluene
[0238]
Surface layer coating solution 3:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0239]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
(Average primary particle size: 0.3 μm) 7 parts
600 parts of toluene
[0240]
The surface layer coating solution was continuously applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, “continuous” means that the next coating liquid is laminated by a spray method after the lower layer is coated and before the touch is dried. The surface layer coating solutions 1, 2, and 3 were applied in an amount corresponding to 1 μm to form a total surface layer of 3 μm.
[0241]
( Reference example 2 )
Reference example 1 Except for changing the surface layer coating liquids 1, 2, and 3 to the following compositions, Reference example 1 A photoconductor was prepared in the same manner as described above.
[0242]
Surface layer coating solution 1:
7 parts of a polymeric charge transport material (Mw = 135000) having the following structural formula
[0243]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
Average primary particle size: 0.3 μm) 1 part
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0244]
Surface layer coating solution 2:
7 parts of a polymeric charge transport material (Mw = 135000) having the following structural formula
[0245]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
(Average primary particle size: 0.5 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0246]
Surface layer coating solution 3:
7 parts of a polymeric charge transport material (Mw = 135000) having the following structural formula
[0247]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
(Average primary particle size: 0.3 μm) 3 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0248]
(Comparative Example 6)
Reference example 1 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference example 1 A photoconductor was produced in exactly the same manner as described above.
[0249]
(Comparative Example 7)
Reference example 1 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 3 as the surface layer in Reference example 1 A photoconductor was produced in exactly the same manner as described above.
[0250]
(Comparative Example 8)
Reference example 1 Except that the surface layer is not laminated and the charge transport layer is 25 μm. Reference example 1 A photoconductor was prepared in the same manner as described above.
[0251]
(Comparative Example 9)
Reference example 1 Except for changing the filler (titanium oxide fine particles) contained in the surface layer coating liquid 1, 2 and 3 in the following, Reference example 1 A photoconductor was prepared in the same manner as described above.
[0252]
Filler: conductive titanium oxide (specific resistance: 7.1 × 10 ⁷ Ω · cm)
[0253]
(Comparative Example 10)
Reference example 2 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference example 2 A photoconductor was produced in exactly the same manner as described above.
[0254]
(Comparative Example 11)
Reference example 2 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference example 2 A photoconductor was produced in exactly the same manner as described above.
[0255]
Produced as above Reference example 1 , 2 And the photoconductors of Comparative Examples 6 to 10 were attached to the electrophotographic process shown in FIG. 6 (but no exposure before cleaning), and the image exposure light source was an LED of 655 nm, and 30,000 sheets were continuously printed. The images at that time were evaluated at the initial stage and after 30,000 sheets. Furthermore, the amount of wear on the surface of the photoreceptor on 30,000 sheets was also measured. The above results are also shown in Table 2.
[0256]
[Table 2]

[0257]
( Reference example 3 , 4 )
Reference example 1 Titanate-based coupling agent and Al so that the treatment amount of the filler (titanium oxide fine particles) used in the process is 20 wt%. ₂ O ₃ The surface treatment was performed. Using this filler, Reference example 1 Surface layer coating solutions 1, 2, and 3 were prepared. About these, the average particle diameter in a coating liquid (Horiba Manufacturing Co., Ltd. product: measured by CAPA700) and the settling property of the coating liquid (the degree of sedimentation of the coating liquid particles that were allowed to stand in a test tube were checked with the naked eye) were evaluated. . The results are shown in Table 3. In addition, the value shown in Table 3 is a measurement result of each surface layer coating liquid 3.
[0258]
[Table 3]

[0259]
( Reference Example 5 , 6 )
Reference example 3 , 4 Using the dispersion prepared in Reference example 1 A photoconductor was prepared in the same manner as described above. Moreover, only the surface layer was formed on the polyester film as a transmittance measurement sample. Table 4 shows the appearance results of the photoreceptor, the surface roughness Rz, and the transmittance at 655 nm.
[0260]
[Table 4]

[0261]
( Reference Example 7 , 8 )
Reference Example 5 , 6 The photoconductor produced in step 1 Reference example 1 It was mounted on the same device as that used for the evaluation and image evaluation was performed. as a result, Reference example 1 From a photoreceptor using a dispersion of Reference example 3 , 4 The resolution of the photoreceptor using the dispersion liquid was superior.
[0262]
(Example 6 )
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 and dried on an aluminum cylinder to generate a 3.5 μm undercoat layer and a 0.2 μm charge generation. An electrophotographic photosensitive member comprising a layer, a 21 μm charge transport layer and a 4 μm surface layer was formed.
[0263]
Undercoat layer coating solution:
400 parts of titanium dioxide powder
65 parts of melamine resin
120 parts alkyd resin
2-butanone 400 parts
[0264]
Charge generation layer coating solution:
8 parts titanyl phthalocyanine having the XD spectrum represented in FIG.
Polyvinyl butyral 5 parts
2-butanone 400 parts
[0265]
Charge transport layer coating solution:
10 parts of Z-type polycarbonate
7 parts of charge transport material with the following structural formula
[0266]
Embedded image

80 parts of methylene chloride
[0267]
Surface layer coating solution 1:
10 parts of polyarylate
8 parts of charge transport material of the following structural formula
[0268]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0269]
Surface layer coating solution 2:
10 parts of Z-type polycarbonate
8 parts of charge transport material of the following structural formula
[0270]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 4 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0271]
Surface layer coating solution 3:
10 parts of Z-type polycarbonate
8 parts of charge transport material of the following structural formula
[0272]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 8 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0273]
The surface layer coating solution was continuously applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, “continuous” means that the next coating liquid is laminated by a spray method after the lower layer is coated and before the touch is dried. The surface layer coating liquids 1 and 2 were applied in an amount corresponding to 1.5 μm, and the surface layer coating liquid 3 was applied in an amount corresponding to 1 μm to form a total surface layer of 4 μm.
[0274]
(Comparative Example 12)
Example 6 Example 1 except that only the surface layer coating liquid 1 was used as the surface layer in step 4 and a surface layer corresponding to 4 μm was formed. 6 A photoconductor was produced in exactly the same manner as described above.
[0275]
(Comparative Example 13)
Example 6 In Example, except that only the surface layer coating liquid 3 was used as the surface layer in step 4 and a surface layer corresponding to 4 μm was formed. 6 A photoconductor was produced in exactly the same manner as described above.
[0276]
(Comparative Example 14)
Example 6 Example 1 except that the surface layer is not laminated and the charge transport layer is 25 μm. 6 A photoconductor was prepared in the same manner as described above.
[0277]
Examples produced as described above 6 The photoconductors of Comparative Examples 12 to 14 are mounted on the electrophotographic process cartridge shown in FIG. 5, and the image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), and 20,000 sheets are printed continuously. The images at that time were evaluated at the initial stage and after 20,000 sheets. Further, the amount of wear on the surface of the photoreceptor on 20,000 sheets was also measured. The above results are also shown in Table 5.
[0278]
[Table 5]

[0279]
(Example 7 )
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 and dried on an aluminum cylinder to generate a 3.5 μm undercoat layer and a 0.2 μm charge generation. An electrophotographic photosensitive member comprising a layer, a 20 μm charge transport layer, and a 5 μm surface layer was formed. The undercoat layer, the charge generation layer, and the charge transport layer were applied by a dip coating method, and the surface layer was applied by a spray method.
[0280]
Undercoat layer coating solution:
400 parts of titanium dioxide powder
65 parts of melamine resin
120 parts alkyd resin
2-butanone 400 parts
[0281]
Charge generation layer coating solution:
10 parts of bisazo pigment with the following structure
[0282]
Embedded image

Polyvinyl butyral 2 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0283]
Charge transport layer coating solution:
10 parts of A type polycarbonate
8 parts of charge transport material of the following structural formula
[0284]
Embedded image

Tetrahydrofuran 200 parts
[0285]
Surface layer coating solution 1:
10 parts of A type polycarbonate
7 parts of charge transport material with the following structural formula
[0286]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0287]
Surface layer coating solution 2:
10 parts of A type polycarbonate
7 parts of charge transport material with the following structural formula
[0288]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 4 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0289]
Surface layer coating solution 3:
10 parts of A type polycarbonate
7 parts of charge transport material with the following structural formula
[0290]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 7 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0291]
The surface layer coating solution was sequentially applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, the sequential coating refers to laminating the next coating liquid by spraying after the touch-drying is completed after coating the lower layer. The surface layer coating liquids 1 and 2 were applied in an amount corresponding to 2 μm, and the surface layer coating liquid 3 was applied in an amount corresponding to 1 μm to form a total surface layer of 5 μm.
[0292]
(Example 8 )
Example 7 Except for changing the surface layer coating solutions 1, 2, and 3 to those having the following compositions in Examples 7 Similarly, a photoreceptor was produced.
[0293]
Surface layer coating solution 1:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0294]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
Average primary particle size: 0.3 μm) 1 part
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0295]
Surface layer coating solution 2:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0296]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0297]
Surface layer coating solution 3:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0298]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.3 μm) 3 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0299]
(Comparative Example 15)
Example 7 Example 1 except that only the surface layer coating solution 1 was used as the surface layer in 5 to form a surface layer corresponding to 5 μm. 7 A photoconductor was produced in exactly the same manner as described above.
[0300]
(Comparative Example 16)
Example 7 Example 1 except that only the surface layer coating solution 3 was used as the surface layer in 5 to form a surface layer corresponding to 5 μm. 7 A photoconductor was produced in exactly the same manner as described above.
[0301]
(Comparative Example 17)
Example 7 Except that the filler (alumina fine particles) contained in the surface layer coating liquids 1, 2, and 3 in Example 1 was changed to the following: 7 A photoconductor was prepared in the same manner as described above.
Filler: Conductive tin oxide (specific resistance: 5 × 10 ⁵ (Ω · cm, average primary particle size: 0.3 μm)
[0302]
(Comparative Example 18)
Example 8 Example 1 except that only the surface layer coating solution 1 was used as the surface layer in 5 to form a surface layer corresponding to 5 μm. 8 A photoconductor was produced in exactly the same manner as described above.
[0303]
(Comparative Example 19)
Example 8 Example 1 except that only the surface layer coating solution 1 was used as the surface layer in 5 to form a surface layer corresponding to 5 μm. 8 A photoconductor was produced in exactly the same manner as described above.
[0304]
Examples produced as described above 7 , 8 The photoconductors of Comparative Examples 15 to 19 were mounted on the electrophotographic process shown in FIG. 5 (no exposure before cleaning, the charging member was a scorotron charger), and an image exposure light source was a 655 nm semiconductor laser (using a polygon mirror). As an image writing), 20,000 sheets were continuously printed, and the images at that time were evaluated at the initial stage and after 20,000 sheets. In addition, the amount of wear on the surface of the photoreceptor on 20,000 sheets was also measured. The above results are also shown in Table 6.
[0305]
[Table 6]

[0306]
(Example 9 )
Example 7 The charging member used in the electrophotographic process shown in FIG. 5 was changed from the scorotron charger to the charging roller, and arranged so that the charging roller was in contact with the photoreceptor. Examples of this device 7 The photoconductor prepared in Example 1 was mounted and the following charging conditions were used for the examples. 7 The same evaluation was performed.
[0307]
Charging conditions:
DC bias: -930V
As a result, both the initial image and the 20,000th image were good, but the image after 20,000th image was found to have a very slight abnormal image (ground stain) based on the charging roller stain (toner filming). It was. However, ozone odor during continuous printing is an example. 7 Compared to the case, it was much less.
[0308]
(Example 10 )
Example 9 Insulating tape having a thickness of 50 μm and a width of 5 mm was attached to both ends of the charging roller used in the above, and arranged so as to have a spatial gap (50 μm) between the charging roller surface and the photoreceptor surface. Other conditions are examples 9 Evaluation was performed in exactly the same way. As a result, the example 9 No smearing of the charging roller was observed, and the initial image and the 20,000th image were both good. However, when a halftone image was output after 20,000 sheets, image unevenness based on charging unevenness was recognized although it was very slight.
[0309]
(Example 11 )
Example 10 In the evaluation of the example, except that the charging conditions were changed as follows: 10 The same evaluation was performed.
[0310]
Charging conditions:
DC bias: -900V
AC bias: 2.0 kV (peak to peak), frequency 2 kHz
The initial image and the image after 20,000 sheets were good. Example 9 Example of charging roller contamination recognized in Example 10 No halftone image irregularity was observed in the image.
[0311]
( Reference Example 9 )
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 and dried on a nickel belt, and a 3 μm undercoat layer, a 0.3 μm charge generation layer, An electrophotographic photosensitive member having a 22 μm charge transport layer and a 3 μm surface layer was formed. The undercoat layer, the charge generation layer, and the charge transport layer were applied by a dip coating method, and the surface layer was applied by a spray method.
[0312]
Undercoat layer coating solution:
100 parts of titanium dioxide powder
100 parts of alcohol-soluble nylon
500 parts of methanol
300 parts of butanol
[0313]
Charge generation layer coating solution:
10 parts of bisazo pigment with the following structure
[0314]
Embedded image

Polyvinyl butyral 2 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0315]
Charge transport layer coating solution:
10 parts of Z-type polycarbonate
7 parts of charge transport material with the following structural formula
[0316]
Embedded image

Tetrahydrofuran 200 parts
[0317]
Surface layer coating solution 1:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0318]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
Average primary particle size: 0.4 μm) 1.5 parts
600 parts of toluene
[0319]
Surface layer coating solution 2:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0320]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
(Average primary particle size: 0.4 μm) 4 parts
600 parts of toluene
[0321]
Surface layer coating solution 3:
10 parts of Z-type polycarbonate
6 parts of charge transport material of the following structural formula
[0322]
Embedded image

Titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm,
(Average primary particle size: 0.4 μm) 7 parts
600 parts of toluene
[0323]
The surface layer coating solution was sequentially applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, the sequential coating refers to laminating the next coating liquid by spraying after the touch-drying is completed after coating the lower layer. The surface layer coating solutions 1, 2, and 3 were applied in an amount corresponding to 1 μm to form a total surface layer of 3 μm.
[0324]
( Reference Example 10 )
Reference Example 9 Except for changing the surface layer coating liquids 1, 2, and 3 to the following compositions, Reference Example 9 A photoconductor was prepared in the same manner as described above.
[0325]
Surface layer coating solution 1:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0326]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
Average primary particle size: 0.3 μm) 1 part
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0327]
Surface layer coating solution 2:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0328]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
(Average primary particle size: 0.4 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0329]
Surface layer coating solution 3:
7 parts of polymer charge transport material (Mw = 130,000) of the following structural formula
[0330]
Embedded image

Silica fine particles (specific resistance: 4 × 10 ¹³ Ω · cm,
(Average primary particle size: 0.4 μm) 3 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0331]
(Comparative Example 20)
Reference Example 9 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference Example 9 A photoconductor was produced in exactly the same manner as described above.
[0332]
(Comparative Example 21)
Reference Example 9 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 3 as the surface layer in Reference Example 9 A photoconductor was produced in exactly the same manner as described above.
[0333]
(Comparative Example 22)
Reference Example 9 Except that the surface layer is not laminated and the charge transport layer is 25 μm. Reference Example 9 A photoconductor was prepared in the same manner as described above.
[0334]
(Comparative Example 23)
Reference Example 9 Except for changing the filler (titanium oxide fine particles) contained in the surface layer coating liquid 1, 2 and 3 in the following, Reference Example 9 A photoconductor was prepared in the same manner as described above.
[0335]
Filler: conductive titanium oxide (specific resistance: 7.1 × 10 ⁷ Ω · cm)
[0336]
(Comparative Example 24)
Reference Example 10 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference Example 10 A photoconductor was produced in exactly the same manner as described above.
[0337]
(Comparative Example 25)
Reference Example 10 Except for forming the surface layer corresponding to 3 μm using only the surface layer coating liquid 1 as the surface layer in Reference Example 10 A photoconductor was produced in exactly the same manner as described above.
[0338]
Produced as above Reference Example 9 , 10 And the photoconductors of Comparative Examples 20 to 25 were attached to the electrophotographic process shown in FIG. 6 (however, exposure before cleaning was not performed), and the image exposure light source was an LED of 655 nm, and 30,000 sheets were continuously printed. The images at that time were evaluated at the initial stage and after 30,000 sheets. Furthermore, the amount of wear on the surface of the photoreceptor on 30,000 sheets was also measured. The above results are also shown in Table 7.
[0339]
[Table 7]

[0340]
( Reference Example 11 , 12 )
Reference Example 9 Titanate coupling agent and Al so that the amount of treatment used in the filler is 20 wt% ₂ O ₃ The surface treatment was performed. Using this filler, Reference Example 9 Surface layer coating solutions 1, 2, and 3 were prepared. About these, the average particle diameter in a coating liquid (Horiba Manufacturing Co., Ltd. product: measured by CAPA700) and the settling property of the coating liquid (the degree of sedimentation of the coating liquid particles that were allowed to stand in a test tube were checked with the naked eye) were evaluated. . The results are shown in Table 8. In addition, the value shown in Table 8 is a measurement result of each surface layer coating liquid 3.
[0341]
[Table 8]

[0342]
( Reference Example 13 , 14 )
Reference Example 11 , 12 Using the dispersion prepared in Reference Example 9 A photoconductor was prepared in the same manner as described above. Moreover, only the surface layer was formed on the polyester film as a transmittance measurement sample. Table 9 shows the appearance results of the photoreceptor, the surface roughness Rz, and the transmittance at 655 nm.
[0343]
[Table 9]

[0344]
( Reference Example 15 , 16 )
Reference Example 13 , 14 The photoconductor produced in step 1 Reference Example 9 It was mounted on the same device as that used for the evaluation and image evaluation was performed. as a result, Reference Example 9 From a photoreceptor using a dispersion of Reference Example 13 , 14 The resolution of the photoreceptor using the dispersion liquid was superior.
[0345]
(Example 12 )
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 and dried on an aluminum cylinder to generate a 3.5 μm undercoat layer and a 0.2 μm charge generation. An electrophotographic photosensitive member comprising a layer, a 21 μm charge transport layer and a 4 μm surface layer was formed.
[0346]
Undercoat layer coating solution:
400 parts of titanium dioxide powder
65 parts of melamine resin
120 parts alkyd resin
2-butanone 400 parts
[0347]
Charge generation layer coating solution:
8 parts titanyl phthalocyanine having the XD spectrum represented in FIG.
Polyvinyl butyral 5 parts
2-butanone 400 parts
[0348]
Charge transport layer coating solution:
10 parts of Z-type polycarbonate
7 parts of charge transport material with the following structural formula
[0349]
Embedded image

80 parts of methylene chloride
[0350]
Surface layer coating solution 1:
10 parts of polyarylate
8 parts of charge transport material of the following structural formula
[0351]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.4 μm) 2 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0352]
Surface layer coating solution 2:
10 parts of polyarylate
8 parts of charge transport material of the following structural formula
[0353]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.4 μm) 4 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0354]
Surface layer coating solution 3:
10 parts of polyarylate
8 parts of charge transport material of the following structural formula
[0355]
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm,
(Average primary particle size: 0.4 μm) 8 parts
Tetrahydrofuran 400 parts
200 parts of cyclohexanone
[0356]
The surface layer coating solution was sequentially applied by a spray method using three spray heads in the order of the surface layer coating solutions 1, 2, and 3. In this case, the sequential coating refers to laminating the next coating liquid by spraying after the touch-drying is completed after coating the lower layer. The surface layer coating liquids 1 and 2 were applied in an amount corresponding to 1.5 μm, and the surface layer coating liquid 3 was applied in an amount corresponding to 1 μm to form a total surface layer of 4 μm.
[0357]
(Comparative Example 26)
Example 12 Example 1 except that only the surface layer coating liquid 1 was used as the surface layer in step 4 and a surface layer corresponding to 4 μm was formed. 12 A photoconductor was produced in exactly the same manner as described above.
[0358]
(Comparative Example 27)
Example 12 In Example, except that only the surface layer coating liquid 3 was used as the surface layer in step 4 and a surface layer corresponding to 4 μm was formed. 12 A photoconductor was produced in exactly the same manner as described above.
[0359]
(Comparative Example 28)
Example 12 Example 1 except that the surface layer is not laminated and the charge transport layer is 25 μm. 12 A photoconductor was prepared in the same manner as described above.
[0360]
Examples produced as described above 12 The photoconductors of Comparative Examples 26 to 28 are mounted on the electrophotographic process cartridge shown in FIG. 5, and the image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), and 20,000 sheets are continuously printed. The images at that time were evaluated at the initial stage and after 20,000 sheets. Further, the amount of wear on the surface of the photoreceptor on 20,000 sheets was also measured. The above results are also shown in Table 10.
[0361]
[Table 10]

[0362]
(Example 13 )
Example 12 In Example 1, the conductive support (JIS1050) was subjected to the following anodic oxide film treatment, and then an undercoat layer was not provided. 12 In the same manner as above, a charge generation layer, a charge transport layer, and a protective layer were provided to prepare a photoreceptor.
[0363]
[Anodic oxide film treatment]
The surface of the support was mirror-polished, degreased and washed with water, and then immersed in an electrolytic bath with a liquid temperature of 20 ° C. and sulfuric acid of 15 vol%, and an anodized film treatment was performed at an electrolysis voltage of 15 V for 30 minutes. Further, after washing with water, sealing treatment was performed with a 7% nickel acetate aqueous solution (50 ° C.). Thereafter, washing with pure water was performed to obtain a support on which a 6 μm anodic oxide film was formed.
[0364]
Example 12 ,Example 13 7 is mounted on the electrophotographic process cartridge shown in FIG. 7, and the image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), and 20,000 sheets are continuously printed. Images were evaluated initially and after 20,000 images. Comparing the images after 20,000 sheets of both, there is no problem in actual use, but the dirt (black spots) on the background part is an example. 13 Compared to the image of the example 12 There were slightly more.
[0365]
(Example 14 )
The photoconductor produced in Example 1 was mounted on the electrophotographic apparatus shown in FIG. 10, and all four image forming elements were evaluated for 20000 full-color images under the process conditions shown below. The results are shown in Table 11.
[0366]
・ Charging conditions
DC bias: -800V
AC bias: 2.0 kV (peak to peak), frequency 2 kHz
・ Exposure conditions
655nm semiconductor laser (image writing by polygon mirror)
[0367]
(Comparative Example 29)
Example 14 Example 1 except that the photoconductor produced in Comparative Example 1 was used instead of the photoconductor used in Example 1. 14 An image evaluation test was conducted in the same manner as above. The results are shown in Table 11.
[0368]
(Comparative Example 30)
Example 14 Example 1 except that the photoconductor prepared in Comparative Example 2 was used instead of the photoconductor used in Example 1. 14 An image evaluation test was conducted in the same manner as above. The results are shown in Table 11.
[0369]
[Table 11]

[0370]
【The invention's effect】
[0371]
According to the present invention, side effects (such as wear resistance and residual potential generation, improved wear resistance and occurrence of image blur, etc.) occurring in a photoconductor in which a filler is added to the surface layer for high durability of the organic photoconductor. The trade-off relationship) is made such that the filler concentration in the surface layer has a concentration gradient that continuously increases from the photosensitive layer side to the surface side, or the surface layer is composed of a plurality of layers. It has become possible to achieve both by adopting a constitution in which the filler concentration is gradually increased from the photosensitive layer side to the surface side. This provides a photoreceptor that can form a high-quality image that is highly durable and stable for repeated use. There are also provided an electrophotographic method, an electrophotographic apparatus, and an electrophotographic process cartridge capable of forming a stable high-quality image at high speed even after repeated use.
[Brief description of the drawings]
FIG. 1 is a diagram showing a layer structure of an electrophotographic photosensitive member of the present invention.
FIG. 2 is a diagram showing a layer structure of another electrophotographic photosensitive member of the present invention.
FIG. 3 is a diagram showing a layer structure of another electrophotographic photosensitive member of the present invention.
FIG. 4 is a diagram showing a layer structure of still another electrophotographic photosensitive member of the present invention.
FIG. 5 is a diagram for explaining an electrophotographic apparatus of the present invention.
FIG. 6 is a diagram for explaining another electrophotographic apparatus of the present invention.
FIG. 7 is a view for explaining a process cartridge of the present invention.
FIG. 8 Example 6 as well as 12 It is a figure showing the X-ray-diffraction spectrum of the titanyl phthalocyanine used in 1. FIG.
FIG. 9 is a diagram for explaining an example of a proximity charging mechanism in which a gap forming member is disposed on the charging member side.
FIG. 10 is a diagram for explaining a full-color electrophotographic apparatus of the present invention.
[Explanation of symbols]
(In FIGS. 1 to 4)
31 Conductive support
33 Single layer photosensitive layer
35 Charge generation layer
37 Charge transport layer
39 Surface layer
(In FIG. 9)
29 photoconductor
30 Charging roller
31 Gap forming member
32 Metal shaft
33 Image formation area
34 Non-image forming area
(In FIG. 10)
1 Drum photoconductor
2 Charging member
3 Laser light
4 Development member
5 Cleaning members
6 Image forming elements
7 Transfer paper
8 Feed roller
9 Registration roller
10 Transfer conveyor belt
11 Transfer brush
12 Fixing device

Claims (13)

In an electrophotographic photoreceptor comprising a photosensitive layer and a surface layer containing at least an organic charge generating material and an organic charge transport material on a conductive support,
The surface layer contains alumina having a specific resistance of 10 ¹⁰ Ω · cm or more,
An electrophotographic photosensitive member characterized by having a concentration gradient in which the alumina concentration continuously increases from the support side to the surface side. In an electrophotographic photoreceptor comprising a photosensitive layer and a surface layer containing at least an organic charge generating material and an organic charge transport material on a conductive support,
The surface layer is composed of two or more layers,
Each surface layer contains alumina having a specific resistance of 10 ¹⁰ Ω · cm or more,
An electrophotographic photosensitive member characterized in that the alumina concentration increases in order from the support side to the surface side. The electrophotographic photosensitive member according to claim 1 or 2, wherein an alumina concentration in the outermost surface of the surface layer is 5 to 40% by weight with respect to all materials constituting the surface layer. The electrophotographic photosensitive member according to any one of claims 1 to 3, characterized in that it contains a charge transport material in the surface layer. In the manufacturing method of the surface layer of the photoreceptor in any one of Claim 1, 3, and 4 ,
Using two or more coating solutions with different alumina concentrations,
An electrophotographic photosensitive member, which is applied by a spray method in order from a solution having a low alumina concentration, and in this case, the next coating solution is applied and laminated before the coating film previously applied is touch-dried. Manufacturing method. In the method for manufacturing a photosensitive member surface layer as claimed in any one of claims 2-4,
Using two or more coating solutions with different alumina concentrations,
An electrophotography characterized in that the liquid is applied in order from the liquid having the lowest alumina concentration by the spray method, and the next coating liquid is applied and laminated after the previous coating has been dried by touching. A method for producing a photoreceptor. In an electrophotographic method in which at least charging, image exposure, development, and transfer are repeated on an electrophotographic photosensitive member,
An electrophotographic method, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 4 . An electrophotographic apparatus comprising at least a charging means, an image exposure means, a developing means, a transfer means, and an electrophotographic photosensitive member,
An electrophotographic apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 4 . 9. The electrophotographic apparatus according to claim 8, wherein the charging means is a member in which a charging member is placed in contact with or close to the photosensitive member. The electrophotographic apparatus according to claim 9, wherein a gap between the charging member and the photosensitive member is 200 μm or less. The charging means, the DC component to the charging member superimposed AC component, electrophotographic apparatus according to any one of claims 8 to 10, characterized in that to provide a charged photoconductor. A full-color electrophotographic apparatus in which a plurality of image forming elements comprising at least an electrophotographic photosensitive member, a charging unit, an image exposing unit, a developing unit, and a transferring unit are arranged,
A full-color electrophotographic apparatus, wherein the electrophotographic photoreceptor is the electrophotographic photoreceptor according to any one of claims 1 to 4 . A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member,
An electrophotographic photosensitive member according to any one of claims 1 to 4 , wherein the electrophotographic photosensitive member is a process cartridge for an electrophotographic apparatus.

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