JP3871863B2 - Electrophotographic photosensitive member, electrophotographic method using the same, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Description

（式中、Ｒ₁、Ｒ₂、Ｒ₃およびＲ₄は水素元素、置換又は無置換の低級アルキル基、置換又は無置換のアリール基を表し、Ａｒ₁は置換又は無置換のアリール基を表し、Ａｒ₂は置換又は無置換のアリーレン基を表し、Ａｒ₁とＲ₁は共同で環を形成してもよく、またｎは０又は１の整数である。）を用いることにより、高感度で、静電潜像を形成する際、電荷移動時における電荷の散逸の無い極めて良好な高解像な画像を得ることが出来る。
【００１５】
また電荷輸送層の膜厚を特定の値に制限し、特定膜厚の薄膜にすることにより、感光体表面に静電潜像が形成される際の電荷の拡散を抑制出来るため、非常に高密度で微細な書き込みが要求されるような場合に対しても忠実な静電潜像を形成し、高画質な画像を得ることができる。
【００１６】
以下図面に沿って本発明で用いられる電子写真感光体を説明する。
図１は本発明の電子写真感光体の構成を示す断面図であり、導電性支持体３１上に、導電性支持体に接する中間層３２と感光層に接する中間層３３からなる複数の構成の中間層３６と、電荷発生層３４および電荷輸送層３５からなる感光層３７が形成されたものである。
【００１７】
まず、本発明に用いられる導電性支持体について述べる。
本発明に用いられる導電性支持体３１としては、体積抵抗１０¹⁰Ω以下の導電性を示すもの、例えばアルミニウム、ニッケル、クロム、ニクロム、銅、銀、金、白金、鉄などの金属、酸化スズ、酸化インジウムなどの酸化物を、蒸着またはスパッタリングによりフィルム状もしくは円筒状のプラスチック、紙等に被覆したもの、あるいはアルミニウム、アルミニウム合金、ニッケル、ステンレスなどの板およびそれらをＤ．Ｉ．，Ｉ．Ｉ．，押出し、引き抜きなどの工法で素管化後、切削、超仕上げ、研磨などで表面処理した管などを使用することが出来る。
【００１８】
次に本発明に用いられる中間層３６について述べる。本発明における中間層は複数の層３２、及び３３から構成される。本発明の中間層に用いられる結着樹脂は、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。中でもとりわけアルキッド樹脂とメラミン樹脂を用いた場合その特性上良好な膜を得ることが出来る。また、本発明で用いられる無機化合物としては酸化チタン、シリカ、アルミナ、酸化ジルコニウム、酸化スズ、酸化インジウム等の金属酸化物などがあげられ、なかでも酸化チタンを用いた場合に良好な特性が得られる。これらをボールミル等の粉砕方法を用いて微粉末にしたものが用いられる。
【００１９】
本発明では導電性支持体上に中間層を複数設け、この複数の中間層がいずれも無機化合物を含有し、このうち該導電性支持体に接する層（図１中３２）に含まれる無機化合物の平均粒径をＤ₁とし、感光層に接する層(図１中３３)に含まれる無機化合物の平均粒径をＤ₂とした場合、Ｄ₂／Ｄ₁≦１／５の関係を満たせばよいが、好ましくは上記関係を満たす条件のうち、複数層の中間層のうち感光層に近い層に含まれる無機化合物が平均粒径０．１μｍ以下、導電性支持体側に近い層に含まれる無機化合物の平均粒径が１μｍ以下であることが好ましく、無機化合物と結着樹脂の比に関しては複数の中間層それぞれに含まれる無機化合物が結着樹脂１重量部に対し３〜７重量部が好ましい。
【００２０】
本発明の中間層３２、３３はいずれも適当な溶媒、塗工法を用いて浸漬塗工法やスプレーコート、ブレードコート法などの湿式塗工することにより形成することが出来る。
【００２１】
本発明で用いられる複数の中間層の膜厚は特に限定されないがそれぞれ０．１〜２０μｍが適当である。
【００２２】
次に本発明における感光層３６について述べる。
感光層３６は一層で電荷発生と電荷輸送を担う、いわゆる単層型構造でも電荷発生と電荷輸送を異なる層で担う積層型構造でもよい。ここでは電荷発生と電荷輸送をそれぞれ異なる層で担う積層型構造について述べる。
【００２３】
まずこの積層型の感光層のうち、電荷発生を担う電荷発生層３４について説明する。電荷発生層３４は、電荷発生物質を主成分とする層で、必要に応じて結着樹脂を用いることもある。電荷発生物質としては、公知の材料を用いることが出来る。例えば、銅フタロシアニン、鉄フタロシアニンなどの金属フタロシアニン、無金属フタロシアニンなどのフタロシアニン系顔料、アズレニウム塩顔料、スクエアリック酸メチン顔料、カルバゾール骨格を有するアゾ顔料、トリフェニルアミン骨格を有するアゾ顔料、ジフェニルアミン骨格を有するアゾ顔料、ジベンゾチオフェン骨格を有するアゾ顔料、フルオレノン骨格を有するアゾ顔料、オキサジアゾール骨格を有するアゾ顔料、ビススチルベン骨格を有するアゾ顔料、ジスチリルオキサジアゾール骨格を有するアゾ顔料、ジスチリルカルバゾール骨格を有するアゾ顔料、ペリレン系顔料、アントラキノン系または多環キノン系顔料、キノンイミン系顔料、ジフェニルメタン及びトリフェニルメタン系顔料、ベンゾキノン及びナフトキノン系顔料、シアニン及びアゾメチン系顔料、インジゴイド系顔料、ビスベンズイミダゾール系顔料などが挙げられる。
【００２４】
中でも非対称構造を有するジスアゾ顔料、もしくはＹ型オキソチタニウムフタロシアニンがその特性上好ましい。これらの電荷発生物質は２種以上混合して用いることもできる。
【００２５】
電荷発生層３４に必要に応じて用いられる結着樹脂としては、ポリアミド、ポリウレタン、エポキシ樹脂、ポリケトン、ポリカーボネート、シリコーン樹脂、アクリル樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルケトン、ポリスチレン、ポリ‐Ｎ‐ビニルカルバゾール、ポリアクリルアミドなどが用いられる。これらの結着樹脂は、単独または２種以上の混合物として用いることが出来る。
【００２６】
電荷発生層３４を形成する方法には、真空薄膜作製法と溶液分散系からのキャスティング法とが大きく挙げられる。
【００２７】
前者の方法には、真空蒸着法等が用いられ良好に形成できる。また、後述のキャスティング法によって電荷発生層を設けるには、上述した無機系もしくは有機系電荷発生物質を必要ならば結着樹脂と共にテトラヒドロフラン、シクロヘキサノン、ジオキサン、ジクロロエタン、ブタノン等の溶媒を用いてボールミル、アトライター、サンドミル等により分散し、分散液を適度に希釈して塗布することにより、形成できる。塗布は、浸漬塗工法やスプレーコート、ビードコート法などを用いて行なうことができる。
【００２８】
以上のようにして設けられる電荷発生層の膜厚は、０．０１〜５μｍ程度が適当であり、好ましくは０．０５〜２μｍである。
【００２９】
次に、電荷輸送層３５について説明する。
電荷輸送層３５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。
【００３０】
電荷輸送物質には、正孔輸送物質と電子輸送物質とがある。電子輸送物質としては、例えばクロルアニル、ブロムアニル、テトラシアノエチレン、テトラシアノキノジメタン、２，４，７−トリニトロ−９−フルオレノン、２，４，５，７−テトラニトロ−９−フルオレノン、２，４，５，７−テトラニトロキサントン、２，４，８−トリニトロチオキサントン、２，６，８−トリニトロ−４Ｈ−インデノ〔１，２−ｂ〕チオフェン−４−オン、１，３，７−トリニトロジベンゾチオフェン−５，５−ジオキサイド、ベンゾキノン誘導体等の電子受容性物質が挙げられる。
【００３１】
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。
【００３２】
これら多くの電荷輸送物質のなかでも下記一般式で表される構造を有するものを用いた場合特に優れた特性を有する。
【００３３】
【化３】

（式中、Ｒ₁、Ｒ₂、Ｒ₃およびＲ₄は水素元素、置換又は無置換の低級アルキル基、置換又は無置換のアリール基を表し、Ａｒ₁は置換又は無置換のアリール基を表し、Ａｒ₂は置換又は無置換のアリーレン基を表し、Ａｒ₁とＲ₁は共同で環を形成してもよく、またｎは０又は１の整数である。）
【００３４】
次に、Ａｒ₁、Ａｒ₂、Ｒ₁、Ｒ₂、Ｒ₃およびＲ₄で表される置換基の具体例を以下に示す。
【００３５】
【表１】

【表２】

【表３】

【表４】

【表５】

【００３６】
電荷輸送層の結着樹脂としては、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。これらの結着樹脂は、単独または２種以上の混合物として用いることが出来る。
【００３７】
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。ここで用いられる溶剤としては、テトラヒドロフラン、ジオキサン、トルエン、ジクロロメタン、モノクロロベンゼン、ジクロロエタン、シクロヘキサノン、メチルエチルケトン、アセトンなどが用いられる。
【００３８】
また、本発明において電荷輸送層３５中に可塑剤やレベリング剤を添加してもよい。
【００３９】
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等の一般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１００重量部に対して０．１〜３０重量部程度が適当である。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等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１００重量部に対して０．０１〜１重量部程度が適当である。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、酸化防止剤を添加することができる。酸化防止剤は、有機物を含む層ならばいずれに添加してもよいが、電荷輸送物質を含む層に添加すると良好な結果が得られる。
【００４０】
本発明に用いることができる酸化防止剤として、下記のものが挙げられる。
モノフェノール系化合物
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ール、２，６−ジ−ｔ−ブチル−４−エチルフェノール、ステアリル−β−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネートなど。
【００４１】
ビスフェノール系化合物
２，２’−メチレン−ビス−（４−メチル−６−ｔ−ブチルフェノール）、２，２’−メチレン−ビス−（４−エチル−６−ｔ−ブチルフェノール）、４，４’−チオビス−（３−メチル−６−ｔ−ブチルフェノール）、４，４’−ブチリデンビス−（３−メチル−６−ｔ−ブチルフェノール）など。
【００４２】
高分子フェノール系化合物
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）プロピオネート］メタン、ビス［３，３’−ビス（４’−ヒドロキシ−３’−ｔ−ブチルフェニル）ブチリックアシッド］グリコールエステル、トコフェノール類など。
【００４３】
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。
【００４４】
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。
【００４５】
有機硫黄化合物類
ジラウリル−３，３’−チオジプロピオネート、ジステアリル−３，３’−チオジプロピオネート、ジテトラデシル−３，３’−チオジプロピオネートなど。
【００４６】
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。
【００４７】
これら化合物は、ゴム、プラスチック、油脂類などの酸化防止剤として知られており、市販品を容易に入手できる。
【００４８】
本発明における酸化防止剤の添加量は、電荷輸送物質１００重量部に対して０．１〜１００重量部、好ましくは２〜３０重量部である。
【００４９】
次に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２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。
【００５０】
図２において、感光体１はドラム状の形状を示しているが、シート状、エンドレスベルト状のものであっても良い。帯電チャージャ３、転写前チャージャ７、転写チャージャ１０、分離チャージャ１１、クリーニング前チャージャ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）、帯電ローラを始めとする公知の手段が用いられる。
【００５１】
転写手段には、一般に上記の帯電器が使用できるが、図に示されるように転写チャージャと分離チャージャを併用したものが効果的である。
【００５２】
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２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。
【００５３】
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。
【００５４】
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。
【００５５】
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。
【００５６】
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。
【００５７】
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３に示すものが挙げられる。感光体１６は、導電性支持体上に本発明の感光層を有してなるものである。
【００５８】
【発明の実施の形態】
次に、実施例によって本発明を更に詳細に説明するが、本発明は以下の実施例に限定されるものではない。尚、実施例中使用する部は、すべて重量部を表わす。
【００５９】
実施例１
導電性支持体としてφ３０ｍｍのアルミニウムドラム上に、下記に示すようにして作製した中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液、電荷発生層用塗工液、電荷輸送層用塗工液を順次、塗布乾燥することにより、膜厚がそれぞれ３μｍの中間層１と、１μｍの中間層２と、０．２μｍの電荷発生層、及び１８．２μｍの電荷輸送層を形成して、本発明の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．０６μｍとなるように分散条件を整え、中間層２用塗工液とした。
〔電荷発生層用塗工液〕
下記成分を混合しボールミルで分散した。

この分散液を電荷発生層用塗工液とした。
〔電荷輸送層用塗工液〕
下記成分を混合溶解せしめ電荷輸送層用塗工液とした。
下記構造の電荷輸送物質 ７部
【００６０】
【化４】

ポリカーボネート １０部
塩化メチレン １００部
【００６１】
実施例２
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例２の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．６５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．０４μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００６２】
実施例３
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例３の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．６５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．１２μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００６３】
実施例４
実施例１における電荷輸送層に用いた電荷輸送物質を下記に示す構造のものに変えた以外は実施例１と全く同様にして実施例４の電子写真感光体を作製した。
【００６４】
【化５】

実施例５
実施例４において電荷発生層用塗工液において、無金属フタロシアニン顔料〔ファストゲンブルー8120Ｂ（大日本インキ化学工業製）〕に代えてＹ型オキソチタニルフタロシアニン顔料を同量用いた以外は実施例４と全く同様にして実施例５の電子写真感光体を作製した。
【００６５】
実施例６
実施例４において電荷発生層用塗工液を以下のように変更し、膜厚０．３μｍの電荷発生層を形成した以外は実施例４と全く同様にして実施例６の電子写真感光体を得た。
〔電荷発生層用塗工液〕
下記成分を混合しボールミルで分散した。
下記構造のジスアゾ化合物 ５部
【００６６】
【化６】

ポリビニルブチラール（エスレックＢＬ−Ｓ：積水化学製） １部
シクロヘキサノン ３０部
メチルエチルケトン ３０部
この分散液を電荷発生層用塗工液とした。
【００６７】
実施例７
実施例４において電荷発生層用塗工液を以下のように変更し、膜厚０．３μｍの電荷発生層を形成した以外は実施例４と全く同様にして実施例７の電子写真感光体を得た。
〔電荷発生層用塗工液〕
下記成分を混合しボールミルで分散した。
下記構造のトリスアゾ化合物 ５部
【００６８】
【化７】

ポリビニルブチラール（エスレックＢＬ−Ｓ：積水化学製） １部
シクロヘキサノン ３０部
メチルエチルケトン ３０部
この分散液を電荷発生層用塗工液とした。
【００６９】
実施例８
実施例１において、電荷発生層、電荷輸送層をそれぞれ設けるかわりに下記感光層用塗工液を用いて膜厚１９．５μｍの感光層を設けた以外は実施例１と全く同様にして実施例８の電子写真感光体を作製した。
〔感光層用塗工液〕
下記成分を混合しボールミルで分散した。
下記構造の電荷輸送物質 ５０部
【化８】

下記構造のジスアゾ化合物 ５部
【化９】

Ｚ型ポリカーボネート（分子量６万） ９７部
テトラヒドロフラン ３２８部
この分散液を電荷発生層用塗工液とした。
【００７０】
実施例９
実施例５において、電荷輸送層の膜厚を２５μｍ設けた以外は実施例５と全く同様にして実施例９の電子写真感光体を作製した。
【００７１】
実施例１０
実施例１において、中間層２（感光層側）用塗工液のみ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例１０の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記アルミナ粉末の平均粒子径が０．０８μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００７２】
実施例１１
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例１１の電子写真感光体を得た。
〔中間層１用塗工液〕
酸化チタン粉末〔ＴＡ−300(富士チタン工業製)〕 ４５部
ポリアミド樹脂〔アミランＣＭ−8000 (東レ社製)〕 １４２．５部
導電性ポリマー〔ケミスタット6120（三洋化成社製）〕 ７．２部
硫酸リチウム ０．６４部
メタノール ４００部
イオン交換水 ４５．５部
上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．４μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．０３μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００７３】
実施例１２
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、複数の中間層それぞれに含まれる無機化合物が結着樹脂１重量部に対し２重量部として、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例１２の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．０６μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００７４】
実施例１３
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、複数の中間層それぞれに含まれる無機化合物が結着樹脂１重量部に対し８重量部として、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして実施例１３の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボ−ルミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．０６μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００７５】
比較例１
実施例１において中間層を全く設けなかった以外は実施例１と全く同様にして比較例１の電子写真感光体を作製した。
【００７６】
比較例２
実施例１において中間層２用塗工液を用いず、中間層１用塗工液のみで膜厚４．５μｍの一層の中間層とした以外は実施例１と全く同様にして比較例２の電子写真感光体を作製した。
【００７７】
比較例３
実施例１において中間層１用塗工液を用いず、中間層２用塗工液のみで膜厚４．５μｍの一層の中間層とした以外は実施例１と全く同様にして比較例３の電子写真感光体を作製した。
【００７８】
比較例４
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして比較例４の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．６μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．１５μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００７９】
比較例５
実施例１における中間層１(導電性支持体側)用塗工液、中間層２（感光層側）用塗工液をそれぞれ以下のように変更し、膜厚を４．５μｍの中間層１と、０．８μｍの中間層２とした以外は実施例１と全く同様にして比較例５の電子写真感光体を得た。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．５μｍとなるように分散条件を整え、中間層１用塗工液とした。

上記成分を混合しボールミル粉砕をおこない上記酸化チタン粉末の平均粒子径が０．２５μｍとなるように分散条件を整え、中間層２用塗工液とした。
【００８０】
このようにして作製した実施例１〜１３および比較例１〜５の電子写真感光体を電子写真複写機イマジオＭＦ２２００［（株）リコー製］改造機（書き込みレーザー光源波長６５５ｎｍ）により、それぞれの感光体について４００００枚までの通紙試験を行った。通紙試験初期、及び通紙試験４００００枚後に感光体の、電位特性、画像品質特性の評価を適時行った。
【００８１】
暗部電位：一次帯電の後、現像部位置まで移動した際の感光体表面電位
明部電位：一次帯電後、画像露光(ベタ露光)を受け、現像部位置まで移動した際の感光体表面電位
画像品質：ベタ濃度、細線再現性、黒ポチなどの局所欠陥、地肌汚れ、異常画像等総合的に評価
評価結果を表−１に示す。
【００８２】
【表６】

表−１より明らかなように、本発明の特許請求の範囲を満たす実施例１〜１３の電子写真感光体は、暗部電位明部電位の再現性に優れ、電気特性の劣化が少なく、高画質のハードコピーを長期間安定して得られる事がわかる。一方比較例１〜５の電子写真感光体では電気特性、画像品質の両方、もしくはいずれかが大きく劣化してしまい、本発明の感光体の優位性が明らかである。
【００８３】
【発明の効果】
以上説明したように、本発明により光感度特性、耐久性、画質安定性に優れた電子写真感光体を得ることができる。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の一例の構成を示す断面図である。
【図２】本発明の電子写真プロセスおよび電子写真装置の一例の概略図である。
【図３】本発明のプロセスカートリッジの一般的な例の概略図である。
【符号の説明】
３１ 導電性支持体
３２ 導電性支持体に接する中間層
３３ 感光層に接する中間層
３４ 電荷発生層
３５ 電荷輸送層
３６ 中間層
３７ 感光層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member for use in an electrophotographic process such as an electrophotographic copying machine, a facsimile machine, a laser printer, and a direct digital plate making machine. More specifically, the present invention relates to high sensitivity, high image quality, and extremely high durability. The present invention relates to an electrophotographic photosensitive member excellent in the above, an electrophotographic method using the electrophotographic photosensitive member, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.
[0002]
[Prior art]
An electrophotographic method using an electrophotographic photosensitive member applied to a copying machine, a facsimile, a laser printer, a direct digital plate making machine, etc., is at least after undergoing the processes of primary charging, image exposure, and development on the electrophotographic photosensitive member. This is a method comprising a process of transferring a toner image to an image holding member (transfer paper), fixing, and cleaning the surface of the electrophotographic photosensitive member.
[0003]
The basic characteristics required for electrophotographic photoreceptors in this electrophotographic method are:
(1) Capable of being charged to an appropriate potential in the dark
(2) Less charge dissipation in the dark
(3) The ability to quickly dissipate charges by light irradiation
Etc.
[0004]
In addition to these characteristics, long-term reliability such as image quality characteristics, low pollution, and low cost are also required.
[0005]
An electrophotographic photoreceptor basically comprises a support and a photosensitive layer formed on the support. As the support, a highly conductive metal is often used, and among these, aluminum and aluminum alloys are often used. On these surfaces, there are structural defects such as protrusions and foreign matters, oil such as rust preventive oil, chemical impurities, etc., so if a photosensitive layer is provided on the support as it is, image defects and the like will occur. Then it cannot be used.
[0006]
As one of techniques for solving this problem, it has been proposed to provide a photosensitive layer after providing an intermediate layer on a conductive support. Examples of this include a resin layer provided on a conductive support, an intermediate layer in which an inorganic pigment (titanium oxide, tin oxide, etc.) is dispersed in a resin (JP-A-61-204642, etc.), etc. It has been known.
[0007]
This method is applied to many photoconductors because of its relatively low cost and good effect. However, in an electrophotographic photosensitive member having an intermediate layer of resin only or an intermediate layer in which an inorganic pigment is dispersed in the resin, it cannot be said that there is no problem in electrostatic repetitive characteristics, and in particular, according to repeated use. There has been a problem that electrophotographic characteristics are deteriorated, in particular, the charging potential is lowered, or the surface potential is lowered in the time from charging to development, so-called dark decay is increased. Even when there is no problem in electrostatic electrophotographic characteristics, when an image is formed through an electrophotographic process such as a general Carlson process or a similar process, image defects called white spots and black spots are generated. Many cases occurred.
[0008]
Therefore, these conventional photoconductors are still insufficient in terms of image quality stability upon repeated use.
That is, an electrophotographic photosensitive member satisfying all of charging stability, photosensitivity and image quality and having long-term sustainability of these characteristics has not been obtained. In other words, the conventional electrophotographic photoreceptors are insufficient to achieve the high performance, long life, and high reliability demanded in recent years for electrophotographic engines, and improvement has been strongly desired.
[0009]
[Problems to be solved by the invention]
The present invention is to provide an organic electrophotographic photosensitive member that achieves this high image quality, long life, and high reliability at a high level, and is particularly excellent in image quality reproducibility, durability, and photosensitivity. It is an object of the present invention to provide a photographic photoreceptor, an electrophotographic method using the same, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.
[0010]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have provided a plurality of intermediate layers made of an inorganic compound and a binder resin on a conductive support, and among these intermediate layers, the average of the inorganic compounds contained in the layer in contact with the photosensitive layer We found that the stability of image quality can be improved by making the particle size smaller than the average particle size of the inorganic compound contained in the layer in contact with the conductive support and satisfying a certain relationship with this average particle size. . That is, the average particle diameter of the inorganic compound contained in the layer in contact with the conductive support among the plurality of intermediate layers is D ₁ And the average particle size of the inorganic compound contained in the layer in contact with the photosensitive layer is D ₂ D ₂ / D ₁ It has also been found that very good characteristics can be obtained when the relationship of ≦ 1/5 is satisfied, and that great advantages can be obtained in designing various electrophotographic image forming apparatuses.
[0011]
In the electrophotographic photoreceptor of the present invention, an image free from image quality defects can be obtained by forming a layer of an inorganic compound having a small average particle diameter and a binder resin in the intermediate layer on the side in contact with the photosensitive layer, and also on the support side. The layer in contact with the layer contains an inorganic compound with a larger particle size compared to this, maintaining appropriate resistance, greatly improving the potential stability during repeated use, and scraping due to such repeated use. It has been found that it is possible to effectively prevent the charge injection from the substrate even under a high electric field resulting from the thinning of the photosensitive layer due to the above, and to stably obtain the above-mentioned high-quality image even when repeatedly used. It was.
[0012]
In addition, when the inorganic compound is used in an amount of 3 to 7 parts by weight with respect to 1 part by weight of the binder resin, the charging stability during repeated use is further improved, and alkyd resin and melamine resin are used as these binder resins. As a result, a high-quality film having no coating film defects can be obtained, and a higher-quality image can be obtained.
[0013]
In addition, in the present invention, the charge generation material contained in the charge generation layer is an asymmetric disazo pigment or Y-type oxytitanyl phthalocyanine, and the charge transport material has a structure represented by the following general formula in the charge transport layer,
[0014]
[Chemical 2]

(Wherein R ₁ , R ₂ , R _Three And R _Four Represents a hydrogen element, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, Ar ₁ Represents a substituted or unsubstituted aryl group, Ar ₂ Represents a substituted or unsubstituted arylene group, Ar ₁ And R ₁ May jointly form a ring, and n is an integer of 0 or 1. ), When forming an electrostatic latent image with high sensitivity, it is possible to obtain a very good high-resolution image without charge dissipation during charge transfer.
[0015]
Also, by limiting the film thickness of the charge transport layer to a specific value and making it a thin film with a specific film thickness, it is possible to suppress the diffusion of charges when an electrostatic latent image is formed on the surface of the photoreceptor. A faithful electrostatic latent image can be formed and a high-quality image can be obtained even when fine writing with high density is required.
[0016]
The electrophotographic photoreceptor used in the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing the structure of the electrophotographic photosensitive member of the present invention. The electrophotographic photosensitive member of the present invention has a plurality of structures comprising an intermediate layer 32 in contact with the conductive support and an intermediate layer 33 in contact with the photosensitive layer on the conductive support 31. An intermediate layer 36 and a photosensitive layer 37 composed of a charge generation layer 34 and a charge transport layer 35 are formed.
[0017]
First, the conductive support used in the present invention will be described.
The conductive support 31 used in the present invention has a volume resistance of 10 ^Ten Conductives with a conductivity of Ω or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, iron, and oxides such as tin oxide and indium oxide are deposited or sputtered into a film or cylinder Plastic, paper, etc., or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. I. , I. I. , Pipes that have been surface-treated by cutting, super-finishing, polishing, etc. can be used after making the pipes by a method such as extrusion or drawing.
[0018]
Next, the intermediate layer 36 used in the present invention will be described. The intermediate layer in the present invention is composed of a plurality of layers 32 and 33. The binder resin used in the intermediate layer of the present invention is preferably a resin having a high solvent resistance with respect to a general organic solvent in consideration of applying the photosensitive layer thereon with a solvent. 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 resins, phenol resins, alkyd resins, and epoxy resins. And curable resins that form a three-dimensional network structure. In particular, when an alkyd resin and a melamine resin are used, a film excellent in characteristics can be obtained. In addition, examples of inorganic compounds used in the present invention include metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide. Among them, good characteristics are obtained when titanium oxide is used. It is done. These are used as a fine powder using a grinding method such as a ball mill.
[0019]
In the present invention, a plurality of intermediate layers are provided on the conductive support, and each of the plurality of intermediate layers contains an inorganic compound, and among these, the inorganic compound contained in the layer in contact with the conductive support (32 in FIG. 1). The average particle size of D ₁ And the average particle diameter of the inorganic compound contained in the layer in contact with the photosensitive layer (33 in FIG. 1) is D ₂ D ₂ / D ₁ It is sufficient that the relationship of ≦ 1/5 is satisfied. Preferably, among the conditions satisfying the above relationship, the inorganic compound contained in a layer close to the photosensitive layer among the plurality of intermediate layers has an average particle size of 0.1 μm or less, and has conductivity. The average particle size of the inorganic compound contained in the layer close to the support side is preferably 1 μm or less. Regarding the ratio of the inorganic compound to the binder resin, the inorganic compound contained in each of the plurality of intermediate layers is 1 part by weight of the binder resin. The amount is preferably 3 to 7 parts by weight.
[0020]
The intermediate layers 32 and 33 of the present invention can be formed by wet coating such as dip coating, spray coating, blade coating using an appropriate solvent and coating method.
[0021]
The thickness of the plurality of intermediate layers used in the present invention is not particularly limited, but is suitably 0.1 to 20 μm.
[0022]
Next, the photosensitive layer 36 in the present invention will be described.
The photosensitive layer 36 may be a so-called single layer structure that is responsible for charge generation and charge transport in one layer, or may be a stacked structure that is responsible for charge generation and charge transport in different layers. Here, a stacked structure in which charge generation and charge transport are handled by different layers will be described.
[0023]
First, the charge generation layer 34 responsible for charge generation in the laminated photosensitive layer will be described. The charge generation layer 34 is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. A known material can be used as the charge generating substance. For example, metal phthalocyanines such as copper phthalocyanine and iron phthalocyanine, phthalocyanine pigments such as metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, and diphenylamine skeletons Azo pigments, azo pigments having a dibenzothiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, distyrylcarbazole Azo pigments having a skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone Pigments, cyanine and azomethine pigments, indigoid pigments, and bisbenzimidazole pigments.
[0024]
Of these, disazo pigments having an asymmetric structure or Y-type oxotitanium phthalocyanine is preferable in view of its characteristics. These charge generation materials can be used in combination of two or more.
[0025]
The binder resin used as necessary for the charge generation layer 34 is polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl. Carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more.
[0026]
As a method for forming the charge generation layer 34, a vacuum thin film manufacturing method and a casting method from a solution dispersion system can be largely mentioned.
[0027]
For the former method, a vacuum deposition method or the like is used, and it can be formed satisfactorily. Further, in order to provide a charge generation layer by a casting method described later, a ball mill using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a binder resin, if necessary, the inorganic or organic charge generation material described above, It can be formed by dispersing with an attritor, sand mill or the like, and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.
[0028]
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.
[0029]
Next, the charge transport layer 35 will be described.
The charge transport layer 35 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
[0030]
Charge transport materials include hole transport materials and electron transport materials. Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
[0031]
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.
[0032]
Among these many charge transport materials, particularly excellent properties are obtained when those having a structure represented by the following general formula are used.
[0033]
[Chemical 3]

(Wherein R ₁ , R ₂ , R _Three And R _Four Represents a hydrogen element, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, Ar ₁ Represents a substituted or unsubstituted aryl group, Ar ₂ Represents a substituted or unsubstituted arylene group, Ar ₁ And R ₁ May jointly form a ring, and n is an integer of 0 or 1. )
[0034]
Next, Ar ₁ , Ar ₂ , R ₁ , R ₂ , R _Three And R _Four Specific examples of the substituent represented by are shown below.
[0035]
[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[0036]
As the binder resin for the charge transport layer, 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, Thermoplastic or thermosetting resins such as urethane resin, phenol resin, alkyd resin and the like can be mentioned. These binder resins can be used alone or as a mixture of two or more.
[0037]
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. As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.
[0038]
In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 35.
[0039]
As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is about 0.1 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Is appropriate. 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 100 parts by weight of the binder resin. About 0.01 to 1 part by weight is appropriate. In the present invention, an antioxidant may be added for the purpose of preventing the decrease in sensitivity and the increase in residual potential, in order to improve environmental resistance. The antioxidant may be added to any layer containing an organic substance, but good results are obtained when it is added to a layer containing a charge transport material.
[0040]
The following are mentioned as antioxidant which can be used for this invention.
Monophenolic compounds
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate and the like.
[0041]
Bisphenol compounds
2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-thiobis- ( 3-methyl-6-t-butylphenol), 4,4′-butylidenebis- (3-methyl-6-t-butylphenol) and the like.
[0042]
High molecular phenolic compounds
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-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4 ′) -Hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, tocophenols and the like.
[0043]
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.
[0044]
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.
[0045]
Organic sulfur compounds
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
[0046]
Organophosphorus compounds
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
[0047]
These compounds are known as antioxidants such as rubbers, plastics, oils and fats, and commercially available products can be easily obtained.
[0048]
The addition amount of the antioxidant in the present invention is 0.1 to 100 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the charge transport material.
[0049]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail.
FIG. 2 is a schematic view 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.
[0050]
In FIG. 2, the photosensitive member 1 has a drum shape, but may be a sheet shape or an endless belt shape. As the charging charger 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.
[0051]
As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.
[0052]
The light source such as the image exposure unit 5 and the charge removal lamp 2 emits 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 step, a static elimination step, a cleaning step, or a pre-exposure step in combination with light irradiation in addition to the steps shown in FIG.
[0053]
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.
[0054]
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.
When this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and when developed with positive (negative) polarity toner, a negative image can be obtained.
[0055]
A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.
[0056]
The above illustrated electrophotographic process is illustrative of an embodiment of the present invention, and of course other embodiments are possible.
[0057]
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 photosensitive member 16 has the photosensitive layer of the present invention on a conductive support.
[0058]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. In addition, all the parts used in an Example represent a weight part.
[0059]
Example 1
Coating solution for intermediate layer 1 (conductive support side), coating solution for intermediate layer 2 (photosensitive layer side), charge generation layer prepared as follows, on an aluminum drum of φ30 mm as a conductive support 17. Coating solution for coating and coating solution for charge transport layer are sequentially applied and dried, so that the intermediate layer 1 having a thickness of 3 μm, the intermediate layer 2 having a thickness of 1 μm, the charge generating layer having a thickness of 0.2 μm, A 2 μm charge transport layer was formed to obtain the electrophotographic photoreceptor of the present invention.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.5 μm. Thus, an intermediate layer 1 coating solution was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.06 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[Coating liquid for charge generation layer]
The following components were mixed and dispersed with a ball mill.

This dispersion was used as a charge generation layer coating solution.
[Coating liquid for charge transport layer]
The following components were mixed and dissolved to form a charge transport layer coating solution.
7 parts of charge transport material with the following structure
[0060]
[Formula 4]

10 parts of polycarbonate
100 parts methylene chloride
[0061]
Example 2
The intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution in Example 1 were changed as follows, and the intermediate layer 1 having a film thickness of 4.5 μm and The electrophotographic photosensitive member of Example 2 was obtained in the same manner as in Example 1 except that the intermediate layer 2 of 0.8 μm was used.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.65 μm. Thus, a coating solution for the intermediate layer 1 was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.04 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0062]
Example 3
The intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution in Example 1 were changed as follows, and the intermediate layer 1 having a film thickness of 4.5 μm and The electrophotographic photosensitive member of Example 3 was obtained in the same manner as in Example 1 except that the intermediate layer 2 having a thickness of 0.8 μm was used.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.65 μm. Thus, a coating solution for the intermediate layer 1 was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.12 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0063]
Example 4
An electrophotographic photoreceptor of Example 4 was produced in the same manner as in Example 1 except that the charge transport material used in the charge transport layer in Example 1 was changed to the one having the structure shown below.
[0064]
[Chemical formula 5]

Example 5
In Example 4, the same amount of Y-type oxotitanyl phthalocyanine pigment was used in place of the metal-free phthalocyanine pigment [Fastgen Blue 8120B (Dainippon Ink and Chemicals)] in the coating solution for charge generation layer in Example 4. In the same manner as described above, an electrophotographic photosensitive member of Example 5 was produced.
[0065]
Example 6
In Example 4, the electrophotographic photoreceptor of Example 6 was changed in the same manner as in Example 4 except that the charge generation layer coating solution was changed as follows to form a charge generation layer having a thickness of 0.3 μm. Obtained.
[Coating liquid for charge generation layer]
The following components were mixed and dispersed with a ball mill.
Disazo compound with the following structure: 5 parts
[0066]
[Chemical 6]

Polyvinyl butyral (ESREC BL-S: manufactured by Sekisui Chemical) 1 part
30 parts of cyclohexanone
30 parts of methyl ethyl ketone
This dispersion was used as a charge generation layer coating solution.
[0067]
Example 7
The electrophotographic photosensitive member of Example 7 was exactly the same as Example 4 except that the charge generation layer coating solution was changed as follows in Example 4 to form a charge generation layer having a thickness of 0.3 μm. Obtained.
[Coating liquid for charge generation layer]
The following components were mixed and dispersed with a ball mill.
5 parts of trisazo compound of the following structure
[0068]
[Chemical 7]

Polyvinyl butyral (ESREC BL-S: manufactured by Sekisui Chemical) 1 part
30 parts of cyclohexanone
30 parts of methyl ethyl ketone
This dispersion was used as a charge generation layer coating solution.
[0069]
Example 8
Example 1 Example 1 was carried out in the same manner as Example 1 except that a photosensitive layer having a thickness of 19.5 μm was provided using the following photosensitive layer coating solution instead of providing the charge generation layer and the charge transport layer. 8 electrophotographic photosensitive member was produced.
[Coating solution for photosensitive layer]
The following components were mixed and dispersed with a ball mill.
50 parts of charge transport material with the following structure
[Chemical 8]

Disazo compound with the following structure: 5 parts
[Chemical 9]

97 parts of Z-type polycarbonate (molecular weight 60,000)
328 parts of tetrahydrofuran
This dispersion was used as a charge generation layer coating solution.
[0070]
Example 9
In Example 5, the electrophotographic photosensitive member of Example 9 was produced in the same manner as Example 5 except that the film thickness of the charge transport layer was 25 μm.
[0071]
Example 10
In Example 1, only the coating liquid for the intermediate layer 2 (photosensitive layer side) was changed as follows, and the film thickness was changed to 4.5 μm intermediate layer 1 and 0.8 μm intermediate layer 2. The electrophotographic photosensitive member of Example 10 was obtained in exactly the same manner as in Example 1.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the alumina powder was 0.08 μm. Thus, an intermediate layer 2 coating solution was obtained.
[0072]
Example 11
The intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution in Example 1 were changed as follows, and the intermediate layer 1 having a film thickness of 4.5 μm and The electrophotographic photoreceptor of Example 11 was obtained in exactly the same manner as in Example 1 except that the intermediate layer 2 having a thickness of 0.8 μm was used.
[Coating liquid for intermediate layer 1]
Titanium oxide powder [TA-300 (Fuji Titanium Industry)] 45 parts
Polyamide resin [Amilan CM-8000 (manufactured by Toray Industries, Inc.)] 142.5 parts
Conductive polymer [Chemist 6120 (manufactured by Sanyo Chemical Co., Ltd.)] 7.2 parts
0.64 parts lithium sulfate
400 parts of methanol
45.5 parts of ion exchange water
The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.4 μm to obtain a coating solution for the intermediate layer 1.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle diameter of the titanium oxide powder was 0.03 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0073]
Example 12
In Example 1, the intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution were changed as follows, and the inorganic compounds contained in each of the plurality of intermediate layers were The electrophotograph of Example 12 is exactly the same as Example 1 except that the amount is 2 parts by weight with respect to 1 part by weight of the binder resin, and the intermediate layer 1 is 4.5 μm and the intermediate layer 2 is 0.8 μm. A photoreceptor was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.5 μm. Thus, an intermediate layer 1 coating solution was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.06 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0074]
Example 13
In Example 1, the intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution were changed as follows, and the inorganic compounds contained in each of the plurality of intermediate layers were The electrophotograph of Example 13 is exactly the same as Example 1 except that the weight is 8 parts by weight with respect to 1 part by weight of the binder resin, and the film thickness is 4.5 μm intermediate layer 1 and 0.8 μm intermediate layer 2. A photoreceptor was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.5 μm. Thus, an intermediate layer 1 coating solution was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.06 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0075]
Comparative Example 1
An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that no intermediate layer was provided in Example 1.
[0076]
Comparative Example 2
Comparative Example 2 was the same as Example 1 except that the intermediate layer 2 coating solution was not used in Example 1 and only the intermediate layer 1 coating solution was used to form a single intermediate layer having a thickness of 4.5 μm. An electrophotographic photosensitive member was produced.
[0077]
Comparative Example 3
Comparative Example 3 was the same as Example 1 except that the intermediate layer 1 coating solution was not used in Example 1 and only the intermediate layer 2 coating solution was used to form a single intermediate layer having a thickness of 4.5 μm. An electrophotographic photosensitive member was produced.
[0078]
Comparative Example 4
The intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution in Example 1 were changed as follows, and the intermediate layer 1 having a film thickness of 4.5 μm and The electrophotographic photosensitive member of Comparative Example 4 was obtained in the same manner as in Example 1 except that the intermediate layer 2 of 0.8 μm was used.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.6 μm. Thus, a coating solution for the intermediate layer 1 was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.15 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0079]
Comparative Example 5
The intermediate layer 1 (conductive support side) coating solution and the intermediate layer 2 (photosensitive layer side) coating solution in Example 1 were changed as follows, and the intermediate layer 1 having a film thickness of 4.5 μm and The electrophotographic photosensitive member of Comparative Example 5 was obtained in the same manner as in Example 1 except that the intermediate layer 2 of 0.8 μm was used.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.5 μm. Thus, an intermediate layer 1 coating solution was obtained.

The above components were mixed and ball milled, and the dispersion conditions were adjusted so that the average particle size of the titanium oxide powder was 0.25 μm. Thus, a coating solution for the intermediate layer 2 was obtained.
[0080]
The electrophotographic photosensitive members of Examples 1 to 13 and Comparative Examples 1 to 5 thus produced were subjected to respective photosensitivity by using an electrophotographic copying machine Imagio MF2200 [manufactured by Ricoh Co., Ltd.] modified machine (writing laser light source wavelength 655 nm). The body was tested up to 40,000 sheets. Evaluation of the potential characteristics and image quality characteristics of the photoconductor was performed in a timely manner at the beginning of the paper passing test and after 40000 sheets of the paper passing test.
[0081]
Dark area potential: Photoreceptor surface potential when moved to the development position after primary charging
Bright part potential: After primary charging, image exposure (solid exposure), and photoreceptor surface potential when moved to the development position
Image quality: Overall evaluation of solid density, fine line reproducibility, local defects such as black spots, background stains, abnormal images, etc.
The evaluation results are shown in Table-1.
[0082]
[Table 6]

As is apparent from Table 1, the electrophotographic photoreceptors of Examples 1 to 13 satisfying the claims of the present invention are excellent in reproducibility of dark part potential bright part potential, little deterioration in electrical characteristics, and high image quality. It can be seen that a hard copy of can be obtained stably for a long time. On the other hand, in the electrophotographic photoreceptors of Comparative Examples 1 to 5, both or both of the electrical characteristics and the image quality are greatly deteriorated, and the superiority of the photoreceptor of the present invention is clear.
[0083]
【The invention's effect】
As described above, an electrophotographic photoreceptor excellent in photosensitivity characteristics, durability, and image quality stability can be obtained by the present invention.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the structure of an example of an electrophotographic photosensitive member of the present invention.
FIG. 2 is a schematic view of an example of an electrophotographic process and an electrophotographic apparatus of the present invention.
FIG. 3 is a schematic view of a general example of a process cartridge of the present invention.
[Explanation of symbols]
31 Conductive support
32 Intermediate layer in contact with conductive support
33 Intermediate layer in contact with photosensitive layer
34 Charge generation layer
35 Charge transport layer
36 middle class
37 Photosensitive layer

Claims (11)

In an electrophotographic photoreceptor in which a plurality of intermediate layers composed of at least an inorganic compound and a binder resin and a photosensitive layer are sequentially formed on a conductive support, the conductive support of the plurality of intermediate layers is formed on the conductive support. When the average particle diameter of the inorganic compound contained in the intermediate layer in contact is D ₁ and the average particle diameter of the inorganic compound contained in the intermediate layer in contact with the photosensitive layer is D ₂ , D ₂ / D ₁ ≦ 1/5 An electrophotographic photoreceptor characterized by satisfying the following relationship: 2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a laminated structure comprising a charge generation layer and a charge transport layer. 3. The electrophotographic photoreceptor according to claim 1, wherein the inorganic compound contained in the intermediate layer is titanium oxide. The electrophotographic photosensitive member according to claim 1, wherein the binder resin contained in the intermediate layer is composed of an alkyd resin and a melamine resin. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the inorganic compound contained in each of the plurality of intermediate layers is 3 to 7 parts by weight with respect to 1 part by weight of the binder resin. 6. The electrophotographic photoreceptor according to claim 2, wherein the charge transport layer contains a charge transport material having a structure represented by the following general formula.

(Wherein R ₁ , R ₂ , R ₃ and R ₄ represent a hydrogen element, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, and Ar ₁ represents a substituted or unsubstituted aryl group. Ar ₂ represents a substituted or unsubstituted arylene group, Ar ₁ and R ₁ may form a ring together, and n is an integer of 0 or 1.) The electrophotographic photosensitive member according to claim 2, wherein the charge generation material contained in the charge generation layer is an asymmetric disazo pigment. The electrophotographic photosensitive member according to claim 2, wherein the charge generation material contained in the charge generation layer is Y-type oxytitanyl phthalocyanine. The electrophotographic photosensitive member according to claim 2, wherein the charge transport layer has a thickness of 20 μm or less. In an electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeatedly performed on an electrophotographic photosensitive member, the electrophotographic photosensitive member is one according to any one of claims 1 to 9. And an electrophotographic method. An electrophotographic apparatus comprising at least an electrophotographic photosensitive member and a process cartridge for an electrophotographic apparatus, wherein the electrophotographic photosensitive member is one according to any one of claims 1 to 9. Process cartridge for photographic apparatus and electrophotographic apparatus.

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