JP3564934B2 - Electrophotographic photoreceptor, method of manufacturing the same, and image forming apparatus using the same - Google Patents

Description

（式中、Ｒ_１ 、Ｒ_２ 及びＲ_３ は、それぞれ水素原子、ハロゲン原子、アルキル基、アルコキシ基または置換アミノ基を示し、Ｔは炭素数１〜１０の枝分かれしていてもよい２価の脂肪族炭化水素基を示す。ｎは０または１である。）
【化６】

（式中、Ａｒ_１ 及びＡｒ_２ は、それぞれアルキル基、フェニル基、アルコキシ基またはアルキル置換フェニル基で置換されていてもよいフェニル基または縮合環基を示し、Ｔは炭素数１〜１０の枝分かれしていてもよい２価の脂肪族炭化水素基を示す。ｎは０または１である。）
【００２０】
上記一般式（Ａ）及び一般式（Ｂ）で表される化合物において、Ｔの具体例を以下に示す。
【化７】

【００２１】
【化８】

【００２２】
上記一般式（Ｂ）で表される化合物において、Ａｒ_１ 及びＡｒ_２ の具体例を以下に示す。
【化９】

【００２３】
上記一般式（Ａ）で表される化合物の具体例を、表１及び表２に示す。
【表１】

【００２４】
【表２】

【００２５】
上記一般式（Ｂ）で表される化合物の具体例を、表３〜表７に示す。
【表３】

【００２６】
【表４】

【００２７】
【表５】

【００２８】
【表６】

【００２９】
【表７】

【００３１】
本発明において、上記したヒドロキシ基を有する電荷輸送材料との重付加反応により結合し、表面保護層に３次元網目状構造を形成するために用いるイソシアネート基含有化合物としては、３個以上のイソシアネート基を有するものが用いられる。具体的には、１，３，６−ヘキサメチレントリイソシアネート、リジンエステルトリイソシアネート、１，６，１１−ウンデカントリイソシアネート、１，８−イソシアネート−４−イソシアネートメチルオクタン、トリフェニルメタントリイソシアネート、トリス（イソシアネートフェニル）チオフォスフェート等のポリイソシアネート単量体等が用いられる。
【００３２】
また、３個以上のイソシアネート基を含有する化合物の中で、最終的に得られる架橋膜の成膜性、耐クラック発生性及び取扱いの容易性等の面から、ポリイソシアネート単量体から得られる誘導体やプレポリマー等の変性体を用いることがより望ましい。これらの例としては、ポリオールを過剰のイソシアネート化合物で変性したウレタン変性体、尿素結合を有する化合物をイソシアネート化合物で変性したビュレット変性体、ウレタン基にイソシアネートが付加したアロファネート変性体等が特に好ましく、その他にもイソシアヌレート変性体、カルボジイミド変性体等が用いられる。さらに、上記ポリイソシアネート変性体に含まれるものであるが、イソシアネート基の活性を一時的にマスクするためのブロッキング剤を反応させたブロックイソシアネートも好ましく用いることができる。ここで、変性に用いるイソシアネートは、官能基数が２のものでもよく、トリレンジイソシアネート（ＴＤＩ）、ジフェニルメタンジイソシアネート（ＭＤＩ）、１，５−ナフチレンジイソシアネート、トリジンジイソシアネート、１，６−ヘキサメチレンジイソシアネート、キシレンジイソシアネート、リジンジイソシアネート、テトラメチルキシレンジイソシアネート等が例示される。
【００３３】
第１の電子写真感光体の表面保護層に用いられるヒドロキシ基及びフッ素原子を有する化合物は、ヒドロキシ基を有する電荷輸送材料とともに、官能基数３以上のイソシアネート化合物との架橋重合反応により膜を形成する。このようにして得られた膜表面は、良好な潤滑性及び離型性を有することから、感光体表面に紙粉やトナーの付着や固着を防止するのに有効である。このヒドロキシ基及びフッ素原子を有する化合物としては、エチレングリコール、プロピレングリコール、またはポリエチレングリコール類等のグリコール類、アクリルポリオールやポリエステルポリオール等のヒドロキシ基を有する各種のポリマーまたはプレポリマー等のヒドロキシ基含有化合物の水素原子をフッ素で置換させたものが用いられる。また、これらのヒドロキシ基含有化合物は、フッ素置換アルキル基を有するものであってもよい。
【００３４】
本発明において使用されるヒドロキシ基及びフッ素原子を有する化合物としては、下記Ｃ−１〜Ｃ−１１に示されるフッ素含有ビスフェノール誘導体が特に好ましい。
【化１０】

【００３５】
第２の電子写真感光体の表面保護層に用いられるビスフェノール化合物は、ヒドロキシ基を有する電荷輸送材料とともに、３個以上のイソシアネート基を有するポリイソシアネート化合物との重付加反応により高い架橋密度で３次元網目状構造を容易に形成することができる。そのため、この表面保護層を有する感光体は、優れた耐摩耗性を示し、さらに交流電圧の印加や放電生成ガス等の強い外的ストレスが負荷されても非常に高い耐久性を示すことになる。また、このビスフェノール化合物は、ヒドロキシ基を有する電荷輸送材料との相溶性に優れているため、網目状構造の中に電荷輸送材料を均一に導入することができることから良好な光電特性を示すものである。
【００３６】
本発明において使用されるビスフェノール化合物としては、下記Ｄ−１〜Ｄ−１２に示される化合物が、耐摩耗性及び光電特性等の点で特に好ましい。
【化１１】

【００３７】
本発明の電子写真感光体において、表面保護層を形成するには、上記した結合材料に、必要に応じて適宜選択した溶剤を加えて得られる塗布液を、感光層の上に塗工した後、架橋重合させることにより成膜させる。
これらの原料混合比は、全ヒドロキシ基の数と全イソシアネート基の数が略等量になるように調合することが好ましい。特に、過剰のヒドロキシ基が未反応の状態で残留していると、表面保護層の親水性が増大して、高温高湿下においては画像特性が低下することがあるため、反応条件等も含めて原料混合比には注意が必要である。また、表面保護層中の電荷輸送材料の含有率は、感光体の電気特性を維持しつつ機械強度も持たせるように決定することが必要であるが、表面保護層全体に占める電荷輸送材料部分の含有量は、５〜９０重量％の範囲とすることが好ましく、より好ましくは２５〜５０重量％である。本発明においては、表面保護層は電荷輸送材料を化学結合により保持するものであるため、従来の電荷輸送層よりも多くの電荷輸送材料を導入させることができる。
【００３８】
本発明における表面保護層には、その成膜性及び可撓性を向上させるために、各種のバインダー樹脂を添加してもよい。このようなバインダー樹脂としては、架橋重合後の膜と相溶性を有するものが用いられ、例えば、ポリカーボネート、ポリエステル、アクリル類、ポリビニルアルコール、ポリアミド等の各種ポリマーが用いられる。しかし、機械的強度及び光電特性を維持するために、表面保護層中のバインダー樹脂の含有量は６０重量％以下にすることが好ましい。
【００３９】
表面保護層を形成するための架橋重合反応は、ヒドロキシ基含有化合物とイソシアネート基含有化合物とを有する塗布液を感光層の上に塗工した後、加熱することにより行う。このヒドロキシ基とイソシアネート基との付加による架橋重合反応は、使用する原料化合物の反応性によって異なるものであるが、一般的には触媒等を添加する必要はなく、加熱するだけで実施することができる。この架橋重合反応を促進させるには、ジブチルチンジラウレート等の有機金属化合物類、無機金属化合物類、モノアミン類、ジアミン類、トリアミン類、環状アミン類、アルコールアミン類、エーテルアミン類等の触媒を常法により添加してもよい。塗布液の塗工時に溶剤を用いている場合には、乾燥工程と同時に、または乾燥工程に引き続いて加熱処理を行うことができる。
【００４０】
本発明において、表面保護層には、帯電器で発生するオゾン等の酸化性ガスによる劣化を防止する目的で、酸化防止剤を添加してもよい。酸化防止剤としては、ヒンダードフェノール系またはヒンダードアミン系を用いることが好ましく、有機硫黄系酸化防止剤、ホスファイト系酸化防止剤、ジチオカルバミン酸塩系酸化防止剤、チオウレア系酸化防止剤、ベンズイミダゾール系酸化防止剤等の公知のものが使用できる。酸化防止剤の添加量としては、表面保護層中で１５重量％以下であることが好ましく、１０重量％以下がより好ましい。
【００４１】
本発明の電子写真感光体に用いる導電性支持体としては、アルミニウム、ニッケル、クロム、ステンレス鋼等の金属類、及びアルミニウム、チタニウム、ニッケル、クロム、ステンレス鋼、金、バナジウム、酸化錫、酸化インジウム、ＩＴＯ等の薄膜を設けたプラスチックフィルム等、または導電性付与剤を塗布または含浸させた紙及びプラスチックフィルム等が挙げられる。これらの導電性支持体は、ドラム状、シート状、プレート状等の適宜の形状で使用されるが、これらに限定されるものではない。さらに、導電性支持体の表面には、必要に応じて、画質に影響のない範囲で各種の処理を行うことができる。例えば、その表面に、酸化処理、薬品処理または着色処理等、または砂目立て等の乱反射処理等を行うことができる。
【００４２】
また、本発明の電子写真感光体には、導電性支持体と感光層の間に下引き層を設けてもよい。この下引き層は、積層構造からなる感光層の帯電時において、導電性支持体から感光層への電荷の注入を阻止するとともに、感光層と導電性支持体とを一体的に接着保持せしめる接着層としての作用、または、場合により、導電性支持体の光の反射光防止作用等を示すものである。
【００４３】
この下引き層には、結着樹脂としてポリエチレン樹脂、ポリプロピレン樹脂、アクリル樹脂、メタクリル樹脂、ポリアミド樹脂、塩化ビニル樹脂、酢酸ビニル樹脂、フェノール樹脂、ポリカーボネート樹脂、ポリウレタン樹脂、ポリイミド樹脂、塩化ビニリデン樹脂、ポリビニルアセタール樹脂、塩化ビニル−酢酸ビニル共重合体、ポリビニルアルコール樹脂、水溶性ポリエステル樹脂、ニトロセルロース、カゼイン、ゼラチン、ポリグルタミン酸、澱粉、スターチアセテート、アミノ澱粉、ポリアクリル酸、ポリアクリルアミド、ジルコニウムキレート化合物、チタニルキレート化合物、チタニルアルコキシド化合物、有機チタニル化合物、シランカップリング剤等の公知の材料が用いられる。これらの材料は、単独でまたは２種以上を混合して用いることができ、また、酸化チタン、酸化ケイ素、酸化ジルコニウム、チタン酸バリウム、シリコーン樹脂等の微粒子と混合して用いることもできる。
下引き層の膜厚は、０．０１〜１０μｍ、好ましくは０．０５〜２μｍが適当であり、また、その塗布方法としては、ブレードコーティング法、ワイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法等の通常の方法を用いることができる。
【００４４】
本発明において、積層型感光体の電荷発生層は、少なくとも電荷発生材料及び結着樹脂を含有する。電荷発生材料としては、非晶質セレン、結晶性セレン−テルル合金、セレン−ヒ素合金、その他のセレン化合物及びセレン合金、酸化亜鉛、酸化チタン等の無機系光導電性材料、フタロシアニン系、スクアリリウム系、アントアントロン系、ペリレン系、アゾ系、アントラキノン系、ピレン系、ピリリウム塩、チアピリリウム塩等の有機顔料及び染料が用いられる。これらの中で、感光体の光感度の点からすると、フタロシアニン系化合物を用いることが好ましく、無金属フタロシアニン、チタニルフタロシアニン、クロロガリウムフタロシアニン、ヒドロキシガリウムフタロシアニン等が好ましいものとして例示できる。特に、フタロシアニン系化合物の中でも、Ｘ線回折スペクトルにおけるブラッグ角（２θ±０．２°）が、７．４°、１６．６°、２５．５°、２８．３°に強い回折ピークを持つ特定の結晶形を有するクロロガリウムフタロシアニン、またはＸ線回折スペクトルにおけるブラッグ角（２θ±０．２°）が、７．５°、９．９°、１２．５°、１６．３°、１８．６°、２５．１°、２８．３°に強い回折ピークを持つ特定の結晶形を有するヒドロキシガリウムフタロシアニンは、可視光から近赤外光までの広い領域の光に対して高い電荷発生効率を有しているから、特に好ましいものである。これらの特定の結晶形を有するフタロシアニン結晶は、以下の合成例に示すようにして得られる。
【００４５】
［合成例１］
１，３−ジイミノイソインドリン３０部及び３塩化ガリウム９．１部をキノリン２３０部中に入れて、２００℃で３時間反応させた後、生成物を濾別し、アセトン及びメタノールで洗浄し、得られた湿ケーキを乾燥することによりクロロガリウムフタロシアニン結晶２８部を得た。次いで、得られたクロロガリウムフタロシアニン結晶３部を自動乳鉢（Ｌａｂ Ｍｉｌｌ ＵＴ−２１型、ヤマト科学社製）で３時間乾式粉砕した後、その０．５部をガラスビーズ（１ｍｍφ）６０部とともに、室温下にベンジルアルコール２０部中で２４時間ミリング処理した後、ガラスビーズを濾別し、さらにメタノール１０部で洗浄し、乾燥させることにより、Ｘ線回折スペクトルにおけるブラッグ角（２θ±０．２°）が、７．４°、１６．６°、２５．５°、２８．３°に強い回折ピークを持つクロロガリウムフタロシアニン結晶を得た。
【００４６】
［合成例２］
合成例１で得られたクロロガリウムフタロシアニン結晶３部を、０℃において濃硫酸６０部に溶解させた後、その溶解液を５℃の蒸留水４５０部に滴下し、結晶を再析出させた。得られた再結晶物を蒸留水及び希アンモニア水等で洗浄した後、乾燥させることにより、ヒドロキシガリウムフタロシアニン結晶２．５部を得た。この結晶を自動乳鉢にて５．５時間粉砕した後、その０．５部をジメチルホルムアミド１５部及びガラスビーズ（１ｍｍφ）３０部とともに２４時間ミリングした後、得られた結晶を分離してメタノールで洗浄した後、乾燥させることにより、Ｘ線回折スペクトルにおけるブラッグ角（２θ±０．２°）が、７．５°、９．９°、１２．５°、１６．３°、１８．６°、２５．１°、２８．３°に強い回折ピークを持つヒドロキシガリウムフタロシアニン結晶を得た。
【００４７】
電荷発生層の結着樹脂としては、ポリビニルブチラール樹脂、ポリビニルホルマール樹脂、部分変性ポリビニルアセタール樹脂、ポリカーボネート樹脂、ポリエステル樹脂、アクリル樹脂、ポリ塩化ビニル樹脂、ポリスチレン樹脂、ポリビニルアセテート樹脂、塩化ビニル−酢酸ビニル共重合体、シリコーン樹脂、フェノール樹脂、ポリ−Ｎ−ビニルカルバゾール樹脂等が用いられるが、これらに限定されるものではない。これらの結着樹脂は、単独で、または２種以上を混合して用いることができる。
【００４８】
電荷発生材料と結着樹脂との配合比（重量比）は、１０：１〜１：１０の範囲が好ましい。また、本発明に用いる電荷発生層の層厚は、一般的には、０．１〜５μｍ、好ましくは０．２〜２．０μｍが適当である。塗布方法としては、ブレードコーティング法、ワイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法等の通常の方法を用いることができる。
【００４９】
さらに、電荷発生層の形成に用いる溶剤としては、メタノール、エタノール、ｎ−プロパノール、ｎ−ブタノール、ベンジルアルコール、メチルセロソルブ、エチルセロソルブ、アセトン、メチルエチルケトン、シクロヘキサノン、酢酸メチル、酢酸ｎ−ブチル、ジオキサン、テトラヒドロフラン、メチレンクロライド、クロロホルム等の通常の有機溶剤を、単独でまたは２種以上を混合して用いることができる。
【００５０】
また、本発明における積層型感光体の電荷輸送層は、少なくとも電荷輸送材料及び結着樹脂を含有する。この電荷輸送層は、低分子分散型電荷輸送層、またはそれ自体が電荷輸送機能を有する高分子電荷輸送層のいずれのものでもよい。電荷輸送材料としては、ｐ−ベンゾキノン、クロラニル、ブロモアニル、アントラキノン等のキノン系化合物、テトラシアノキノジメタン系化合物、２，４，７−トリニトロフルオレノン等のフルオレノン化合物、キサントン系化合物、ベンゾフェノン系化合物、シアノビニル系化合物、エチレン系化合物等の電子吸引性物質、トリアリールアミン化系化合物、ベンジジン系化合物、アリールアルカン系化合物、アリール置換エチレン系化合物、スチルベン系化合物、アントラセン系化合物、ヒドラゾン系化合物等が挙げられ、これらの電荷輸送材料は、単独でまたは２種以上を混合して用いることができる。
【００５１】
本発明における電荷輸送材料として、下記一般式（ａ）で表されるベンジジン系化合物および下記一般式（ｂ）で表されるトリフェニルアミン系化合物は、高い電荷（ホール）輸送能と優れた安定性を有するものであるから、特に好ましいものとして用いられる。これらは、単独でもまたは混合して用いてもよい。
【００５２】
【化１２】

（式中、Ｒ_４ 及びＲ_５ は、同一でも異なっていてもよく、それぞれ水素原子、ハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のアルコキシ基を示す。Ｒ_６ 、Ｒ_７ 、Ｒ_８ 及びＲ_９ は、同一でも異なっていてもよく、それぞれ水素原子、ハロゲン原子、炭素数１〜５のアルキル基、炭素数１〜５のアルコキシ基または炭素数１〜２のアルキル基で置換されたアミノ基を示す。ｐ及びｑは１または２である。）
【００５３】
【化１３】

（式中、Ｒ_１０は、水素原子またはメチル基を示す。Ａｒ_３ 及びＡｒ_４ は、それぞれ置換または未置換のアリール基を示し、その置換アリール基の置換基はハロゲン原子、炭素数１〜５のアルキル基、炭素数１〜５のアルコキシ基または炭素数１〜３のアルキル基で置換されたアミノ基である。ｍは１または２である。）
【００５４】
上記一般式（ａ）で表される化合物の具体例を、表８〜表１０に示す。
【表８】

【００５５】
【表９】

【００５６】
【表１０】

【００５７】
上記一般式（ｂ）で表される化合物の具体例を、表１１〜表１３に示す。
【表１１】

【００５８】
【表１２】

【００５９】
【表１３】

【００６０】
電荷輸送層の結着樹脂としては、ポリカーボネート樹脂、ポリエステル樹脂、メタクリル樹脂、アクリル樹脂、塩化ビニル樹脂、塩化ビニリデン樹脂、ポリスチレン樹脂、ポリビニルアセテート樹脂、スチレン−ブタジエン共重合体、塩化ビニリデン−アクリロニトリル共重合体、塩化ビニル−酢酸ビニル共重合体、塩化ビニル−酢酸ビニル−無水マレイン酸共重合体、シリコーン樹脂、シリコーン−アルキッド樹脂、フェノール−ホルムアルデヒド樹脂、スチレン−アクリル樹脂、スチレン−アルキッド樹脂、ポリ−Ｎ−ビニルカルバゾール、ポリシラン等の公知の樹脂を用いることができる。
【００６１】
さらに、電荷輸送層には、前記した表面保護層に使用される酸化防止剤を添加してもよい。電荷輸送層は最表層ではないため酸化性ガスと直接接触することはないが、これらの酸化性ガスが表面保護層を透過して電荷輸送層にまで浸入することがあるため、これを防止するために適宜使用される。この酸化防止剤の具体例としては、上記したものと同じものが用いられ、その添加量も同様に１５重量％以下であり、好ましくは１０重量％以下である。
【００６２】
電荷輸送層を形成する溶剤としては、ベンゼン、トルエン、キシレン、クロロベンゼン等の芳香族炭化水素類、アセトン、２−ブタノン等のケトン類、塩化メチレン、クロロホルム、塩化エチレン等のハロゲン化脂肪族炭化水素類、テトラヒドロフラン、エチルエーテル、ジオキサン等の環状または直鎖状のエーテル類等の通常の有機溶剤を、単独でまたは２種以上を混合して用いる。
【００６３】
本発明の電子写真感光体において、単層型感光層の場合には、感光層は、少なくとも前記した電荷発生物質及び結着樹脂を用いて形成される。結着樹脂としては、前記した電荷発生層及び電荷輸送層に用いられる結着樹脂と同様のものが使用される。単層型感光層中の電荷発生物質の含有量は、１０〜８５重量％であり、好ましくは２０〜５０重量％である。単層型感光層には、必要に応じて、電荷輸送層の場合と同様の理由から酸化防止剤を添加してもよく、その添加量は、１５重量％以下であり、好ましくは１０重量％以下である。また、単層型感光層には、光電特性を改善する等の目的で、前記した電荷輸送材料を添加してもよい。この場合の添加量は７０重量％以下であり、５０重量％以下にするのが好ましい。
【００６４】
本発明の画像形成装置は、上記した電子写真感光体、及び感光体を所定の表面電位に帯電させる帯電手段を少なくとも有し、静電潜像を形成するための露光手段、静電潜像を可視化するための現像手段、感光体上の現像材を紙等に転写させる転写手段等を適宜有するものである。本発明の電子写真感光体は、帯電手段として、スコロトロン等の非接触帯電方式の画像形成装置に用いることができ、この場合でも、優れた光電特性及び耐久性、特に耐オゾン性を有するものである。さらに、帯電手段として、帯電ロール等の接触帯電方式の画像形成装置に用いる場合には、接触帯電において顕著に現れる感光体の摩耗に対して優れた耐久性を示すことができる。
【００６５】
図１は、本発明の電子写真感光体を用いる画像形成装置の１例を示すものであって、装置の外側に設けられた電源２から電圧が供給される帯電ロール等の帯電器３が、感光体ドラム１の接触するように配設されている。また、感光体ドラム１の周囲には、レーザー露光光学系等の画像入力装置４、磁性一成分トナー等を装填した現像器５、圧力転写器または静電転写器等の転写器６、クリーナー装置８、除電用ＬＥＤアレイ等の除露光器１０が設けられている。なお、７は用紙、９は定着装置である。本発明の画像形成装置においては、帯電器３として、導電性部材である帯電ロールを用いて接触帯電により感光体ドラム１を帯電させるには、帯電ロールに印加電圧として、直流電圧及び交流電圧を重畳させて画像形成を行うものである。
【００６６】
接触帯電を行う導電性部材の形状は、ブラシ状、ブレード状、ピン電極状またはローラ状等のいずれも使用できるが、特にローラー状部材が好ましい。このローラー状部材は、通常ローラーの外部から順に抵抗層、それらを支持する弾性層及び芯材から構成され、さらに、抵抗層の外側には、必要に応じて、保護層を設けることができる。この芯材の材質としては、導電性を有するものであり、通常、鉄、銅、真鍮、ステンレス鋼、アルミニウム、ニッケル等が用いられる。また、その他の導電性粒子等を分散した樹脂成形品等を用いることができる。また、弾性層の材質としては、導電性または半導電性を有するものであり、通常、ゴム材に導電性粒子または半導電性粒子を分散したものが用いられる。ゴム材としては、ＥＰＤＭ、ポリブタジエン、天然ゴム、ポリイソブチレン、ＳＢＲ、ＣＲ、ＮＢＲ、シリコーンゴム、ウレタンゴム、エピクロルヒドリンゴム、ＳＢＳ、熱可塑性エラストマー、ノルボーネンゴム、フロロシリコーンゴム、エチレンオキシドゴム等が用いられる。また、導電性粒子または半導電性粒子としては、カーボンブラック、亜鉛、アルミニウム、銅、鉄、ニッケル、クロム、チタニウム等の金属、ＺｎＯ−Ａｌ_２ Ｏ_３ 、ＳｎＯ_２ −Ｓｂ_２ Ｏ_３ 、Ｉｎ_２ Ｏ_３ −ＳｎＯ_２ 、ＺｎＯ−ＴｉＯ_２ 、ＭｇＯ−Ａｌ_２ Ｏ_３ 、ＦｅＯ−ＴｉＯ_２ 、ＴｉＯ_２ 、ＳｎＯ_２ 、Ｓｂ_２ Ｏ_３ 、Ｉｎ_２ Ｏ_３ 、ＺｎＯ、ＭｇＯ等の金属酸化物を用いることができ、これらの材料は、単独でまたは２種以上を混合して用いてもよく、２種以上を用いる場合には、一方が微粒子状でもよく、この微粒子としてはフッ素系樹脂の微粒子が用いられる。
【００６７】
ローラー状部材の抵抗層及び保護層の材質は、結着樹脂に導電性粒子または半導電性粒子を分散させて、その抵抗値を制御したものであり、抵抗率としては１０^３ 〜１０^１４Ω・ｃｍ、好ましくは１０^５ 〜１０^１２Ω・ｃｍ、より好ましくは１０^７ 〜１０^１２Ω・ｃｍのものが用いられる。また、それらの膜厚としては、０．０１〜１０００μｍ、好ましくは０．１〜５００μｍ、より好ましくは０．５〜１００μｍのものである。この結着樹脂としては、アクリル樹脂、セルロース樹脂、ポリアミド樹脂、メトキシメチル化ナイロン、エトキシメチル化ナイロン、ポリウレタン樹脂、ポリカーボネート樹脂、ポリエステル樹脂、ポリエチレン樹脂、塩化ビニル樹脂、ポリアリレート樹脂、ポリチオフェン樹脂、ＰＦＡ、ＦＥＰ、ＰＥＴ等のポリオレフィン樹脂、スチレン−ブタジエン樹脂等が用いられる。導電性粒子または半導電性粒子としては、弾性層と同様のカーボンブラック、金属、金属酸化物が用いられる。
【００６８】
また、上記の材質には、必要に応じて、ヒンダードフェノール、ヒンダードアミン等の酸化防止剤、クレー、カリオン等の充填剤、シリコーンオイル等の潤滑剤を添加することができる。これらの層を形成するには、ブレードコーティング法、マイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法、真空蒸着法、プラズマコーティング法等の通常の方法を用いることができる。
【００６９】
これらの導電性部材を用いて電子写真感光体を帯電させるには、導電性部材に電圧を印加するが、その印加電圧としては、直流電圧に交流電圧を重畳したものが好ましく、直流電圧のみでは均一な帯電を得ることが難しい。使用する電圧の範囲としては、直流電圧は、正または負の５０〜２０００Ｖの範囲であることが好ましく、特に１００〜１５００Ｖが好ましい。重畳する交流電圧としては、ピーク間電圧が４００〜１８００Ｖの範囲であり、好ましくは８００〜１６００Ｖ、より好ましくは１２００〜１６００Ｖである。交流電圧の周波数としては、５０〜２００００Ｈｚの範囲であり、好ましくは１００〜２０００Ｈｚである。
【００７０】
【実施例】
以下、本発明を実施例によって具体的に説明するが、本発明はこれらに限定されるものではない。なお、「部」は、いずれも「重量部」を意味する。
実施例１
アルミニウムパイプ上に、ジルコニウム化合物（オルガチックスＺＣ５４０、マツモト製薬社製）１０部、シラン化合物（Ａ１１１０、日本ユニカー社製）１部とイソプロパノール４０部及びブタノール２０部からなる溶液を浸漬コーティング法により塗布し、１５０℃において１０分間加熱乾燥させて、膜厚０．１μｍの下引き層を形成した。
次に、Ｘ型無金属フタロシアニン結晶１部及びポリビニルブチラール（エスレックＢＭ−Ｓ、積水化学社製）１部をシクロヘキサノン１００部と混合し、ガラスビーズとともにサンドミルで１時間分散させた後、上記下引き層の上にディップコートし、その後１００℃で１０分間加熱して膜厚約０．１５μｍの電荷発生層を形成した。
次に、表９中に例示化合物（Ｎｏ．２７）として示されているベンジジン化合物２部及び下記構造式（Ｅ）で示される繰り返し構造単位からなる高分子化合物（粘度平均分子量３９０００）３部をクロロベンゼン２０部に溶解させた塗布液を、前記電荷発生層上に浸漬コーティング法で塗布し、１１０℃で４０分間加熱して膜厚２０μｍの電荷輸送層を形成した。
【００７１】
【化１４】

【００７２】
次に、ヒドロキシ基を有する電荷輸送材料として、表１中の例示化合物（Ａ−１）３部、ヒドロキシ基及びフッ素原子を有する化合物として例示化合物（Ｃ−３）１部、イソシアネート基含有化合物として下記（Ｆ）に示すビュレット変性のポリイソシアネート（固形分約６０重量％）４．７部を、シクロヘキサノン３０部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱して、膜厚５μｍの表面保護層を形成させることにより、電子写真感光体を作製した。
【化１５】

【００７３】
上記のようにして得られた電子写真感光体を、富士ゼロックス社製ＸＰ−１１改造機に装着し、以下の実験を行った。なお、このＸＰ−１１改造機は、図１に示すような帯電ロールによる接触帯電器、レーザー露光光学系、現像器、転写用コロトロン、除電用ＬＥＤ、クリーニングブレード及び定着ロールを有する電子写真プリンターである。
この画像形成装置を用いて、初期画像の画質及び５万枚の連続複写印刷試験後の画質について評価した。また、その試験の前後における膜厚をそれぞれ測定し、その膜厚の減少量を摩耗量とした。なお、帯電は、帯電ロールに直流−５５０Ｖ及び交流１．５ｋＶ_ＰＰ（８００Ｈｚ）を重畳した帯電電圧を印加することによって行った。
【００７４】
比較例１
実施例１において、電荷輸送層の膜厚を２５μｍとしたこと及び表面保護層を設けないこと以外は、実施例１と同様にして電子写真感光体を作製した。
【００８２】
比較例２
実施例１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ヒドロキシ基を有する電荷輸送材料として例示化合物（Ａ−１）３部、例示化合物（Ｃ−３）のフッ素原子を水素で置き換えた化合物１．５部、イソシアネート基含有化合物として前記（Ｆ）４．７部を、シクロヘキサノン２５部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱し、膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
【００８３】
比較例１及び比較例２で得られた電子写真感光体について、実施例１で得られた電子写真感光体と同様に、上記したＸＰ−１１改造機を用いる実験を行った。なお、複写印刷用紙として富士ゼロックス社製中性紙を用いた。さらに、感光体の表面潤滑性を評価するため、酸性紙を用いて１万枚の連続複写印刷試験を行い、感光体表面への紙粉等の付着の影響を評価した。これらの結果を表１４に示す。
【００８４】
【表１４】

【００８５】
表１４に見られるように、酸性紙を用いた連続複写印刷試験においては、実施例１の感光体では問題が発生しなかったが、比較例１のものでは、摩耗量が大きいため光電特性が変化し、表面電位が十分降下しないため画質濃度が低下し、また、現像剤や紙との接触等によって表面に筋状の傷が多発し、これが画質欠陥として現れている。また、比較例２では紙粉（タルク）の付着による画像欠陥が著しかった。このことから、表面保護層中にヒドロキシ基及びフッ素原子を有する化合物を含有させることが、感光体表面への異物の付着による画像品質の低下防止に有効であることが分かる。
【００８６】
実施例２〜４
実施例１において、表面保護層の形成に用いるヒドロキシ基を有する電荷輸送材料として、下記表１５に示すものを用いたこと以外は、実施例１と同様にして電子写真感光体を作製し、５万枚の連続複写印刷を行った。
【００８７】
【表１５】

【００８８】
実施例５
実施例１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ヒドロキシ基を有する電荷輸送材料として例示化合物（Ｂ−１９）２部、例示化合物（Ｃ−３）１部、イソシアネート基含有化合物として前記（Ｆ）３部を、シクロヘキサノン３０部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱し、膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
【００８９】
実施例６〜７
実施例５において、例示化合物（Ｂ−１９）の代りに下記表１６に示すものを用いたこと以外は、実施例５と同様にして電子写真感光体を作製し、同様の評価を行った。
実施例８〜１０
実施例１において、表面保護層に用いるヒドロキシ基及びフッ素原子を有する化合物として、例示化合物（Ｃ−３）の代りに下記表１６に示すものを用いたこと以外は、実施例１と同様にして電子写真感光体を作製し、同様の評価を行った。
【表１６】

【００９０】
実施例２〜１０で得られた評価結果を表１７に示す。
【表１７】

【００９１】
実施例１１
実施例１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ヒドロキシ基を有する電荷輸送材料として例示化合物（Ａ−１）１部、ビスフェノール化合物として例示化合物（Ｄ−１）１部、イソシアネート基含有化合物として前記（Ｆ）に示すビュレット変性のポリイソシアネート（固形分約６７重量％）３部を、シクロヘキサノン１０部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱し、膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
【００９２】
比較例３
実施例１１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ビスフェノール化合物として例示化合物（Ｄ−１）３部、イソシアネート基含有化合物として前記（Ｆ）４部を、キシレン１５部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱して、電荷輸送材料は含まないものの、３次元架橋網目構造のみを有する膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
【００９３】
比較例４
実施例１１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ヒドロキシ基を有する電荷輸送材料として例示化合物（Ａ−１）２部、ビスフェノール化合物として例示化合物（Ｄ−１）２部、イソシアネート基含有化合物として官能基数２の４，４′−ジフェニルメタンジイソシアネート３部をキシレン１０部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱し、膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
実施例１１、比較例１、３及び４で得られた電子写真感光体について、実施例１で得られた電子写真感光体と同様に、上記したＸＰ−１１改造機を用いる実験を行った。これらの評価結果を表１８に示す。
【表１８】

【００９４】
実施例１１で得られた電子写真感光体を用いたものは、初期画像の画質特性が良好であり、かつ５万枚の複写後にも良好な画質特性を維持していた。この初期画質が良好なのは、表面保護層が電荷輸送材料を含有しているために、感光体の光電特性が優れていることによるものである。このことは、表面保護層中に電荷輸送材料を含まない比較例３の感光体との比較からも明らかである。また、５万枚複写した後においても良好な画質特性を維持しているのは、感光体の摩耗量が小さく、同時に感光体表面に傷がつき難いことによるものである。これに対し、５万枚複写した後においては、比較例４のものでは、摩耗量が大きく、さらに表面に筋状の傷が多発し、これが画像欠陥となって現われた。このことから、表面保護層の構成材料として、官能基数３以上を有する結合材料を用いることが架橋密度の高い３次元網目構造を形成し、接触帯電における交流電圧印加に対する耐久性の付与に有効であることが分かる。
【００９５】
実施例１２〜１４
実施例１１において、表面保護層に用いるヒドロキシ基を有する電荷輸送材料として、下記表１９に示すものを用いたこと以外は、実施例１１と同様にして電子写真感光体を作製し、同様の評価を行った。
【００９６】
実施例１５
実施例１１と同様にして、アルミニウムパイプ上に、下引き層、電荷発生層及び電荷輸送層を順次形成した。
次に、ヒドロキシ基を有する電荷輸送材料として例示化合物（Ｂ−１９）２部、ビスフェノール化合物として例示化合物（Ｄ−１）１部、イソシアネート基含有化合物として前記（Ｆ）のポリイソシアネート３部を、シクロヘキサノンとキシレン（重量比、１：２）との混合溶媒１０部に溶解させ、得られた溶液を上記電荷輸送層の上にスプレーコートし、常温で１０分間乾燥させた後、１５０℃で６０分間加熱し、膜厚５μｍの表面保護層を形成させることにより電子写真感光体を作製した。
【００９７】
実施例１６〜１７
実施例１５において、表面保護層に用いるヒドロキシ基を有する電荷輸送材料として、下記表１９に示すものを用いたこと以外は、実施例１５と同様にして電子写真感光体を作製し、同様の評価を行った。
【表１９】

【００９８】
実施例１８〜１９
実施例１１において、表面保護層に用いるビスフェノール化合物として、表２０に示すものを用いたこと以外は、実施例１１と同様にして電子写真感光体を作製し、同様の評価を行った。
【表２０】

【００９９】
実施例１２〜１９で得られた電子写真感光体の評価結果を表２１に示す。
【表２１】

【０１０３】
【発明の効果】
本発明の電子写真感光体は、表面保護層が電荷輸送材料を含む３次元網目状構造を有するもので形成されているため、良好な光電特性及び優れた耐摩耗性等の機械的強度を有しており、さらには、交流電圧の印加及び放電生成ガス等の強い外的ストレスに対しても高い耐久性を有するものである。したがって、この電子写真感光体を用いた画像形成装置は、多数枚の複写後においても良好な画質の画像を維持することができる。
【図面の簡単な説明】
【図１】本発明における画像形成装置の１例を示す概略断面図である。
【符号の説明】
１…感光体ドラム、２…電源、３…帯電器、４…画像入力装置、５…現像器、６…転写器、７…用紙、８…クリーナー装置、９…定着装置、１０…除露光器。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member applicable to a wide range of fields such as a copying machine, a printer, and a facsimile, and an image forming apparatus using the same.
[0002]
[Prior art]
2. Description of the Related Art Generally, an electrophotographic apparatus, for example, a plain paper copier (PPC), a laser printer, an LED printer, a liquid crystal printer, etc., applies an image forming process of charging, exposing, and developing to an electrophotographic photosensitive member such as a rotating drum type. An image is formed, the image is transferred to a transfer member, and then fixed to obtain a copy. In the photosensitive layers of these electrophotographic photosensitive members, inorganic materials such as selenium, arsenic-selenium, cadmium sulfide, zinc chloride, and a-Si are used as photoconductive materials. However, in recent years, research and development of an organic photoreceptor (OPC) using an organic material which is inexpensively available and excellent in manufacturability and disposability as this photoconductive material has been activated. Various proposals have been made because the so-called function-separated type laminated photoreceptor in which the photosensitive layer is formed by laminating a charge generation layer and a charge transport layer has excellent electrophotographic properties such as sensitivity, chargeability and its repetition stability. It has already been put into practical use.
[0003]
However, the requirements for the durability of electrophotographic photoreceptors are becoming increasingly sophisticated, and wear and damage of the surface layer due to repeated use, especially wear and damage of the surface layer which is significantly increased in use by contact charging. It is required to eliminate problems such as deterioration due to oxidation of the surface layer due to oxidizing gas such as ozone generated from the corona charger and durability due to adhesion of toner and the like to the surface of the photoreceptor. R & D is ongoing. As a solution to these problems of the photoreceptor surface layer, a method of forming a surface protective layer mainly containing a cross-linkable curable resin such as an organopolysiloxane on the charge transport layer (Japanese Patent Laid-Open No. 54-148538). Gazette) is known.
[0004]
[Problems to be solved by the invention]
However, if the surface protective layer of the electrophotographic photoreceptor is formed only of a cross-linkable curable resin, the surface protective layer becomes an electrical insulating layer, and thus the photoelectric characteristics of the electrophotographic photoreceptor do not sufficiently exhibit. It was. Specifically, the problem that the development potential margin is narrowed due to an increase in the light portion potential at the time of exposure, and the residual potential after static elimination is increased, especially when long-term repeated copy printing is performed, image density is reduced. There were problems such as lowering.
[0005]
In order to improve the photoelectric characteristics, there is a method in which a conductive metal oxide fine powder is added to the surface protective layer as a resistance control material (JP-A-57-128344). Since the photoreceptor formed by this method has a small decrease in photoelectric characteristics, the above-mentioned problem can be considerably improved. However, in general, the resistance value of the metal oxide used as the conductive fine powder greatly depends on the humidity of the environment, and particularly under high temperature and high humidity, the surface resistance of the photoreceptor decreases and the formed electrostatic latent There is an essential problem that the quality of the formed image is greatly reduced due to the blurred image.
[0006]
As another means for improving the photoelectric characteristics, there is a method of dispersing a charge transport material in a binder resin and then curing the binder resin to form a surface protective layer (Japanese Patent Application Laid-Open No. 4-15659). In this method, since the surface resistance of the photoconductor is not affected by humidity, the image quality does not deteriorate. However, when a charge transporting material composed of a low molecular compound is added to the surface protective layer, the curing reaction is inhibited and the mechanical strength of the surface protective layer is reduced. Therefore, a crosslinked curable resin having high mechanical strength is used alone. However, by adding a charge transporting material composed of a low-molecular compound essential for improving the photoelectric characteristics, the mechanical strength of the surface protective layer is significantly reduced. Further, in the method of preventing abrasion simply by increasing the mechanical strength of the surface protective layer, paper powder and toner attached to the surface of the photoreceptor are easily fixed, and as a result, image quality is greatly reduced. There is also a problem.
[0007]
The present invention has been made in view of the above-described circumstances in the related art. That is, the object of the present invention is to form a surface protective layer having sufficient photoelectric characteristics and excellent mechanical strength such as abrasion resistance, thereby achieving high durability even under long-term use under strong external stress. An object of the present invention is to provide an electrophotographic photosensitive member having a property. Another object of the present invention is to provide a method for easily producing an electrophotographic photoreceptor having a surface protective layer excellent in mechanical strength while sufficiently satisfying photoelectric characteristics. Another object of the present invention is to provide an image forming apparatus using the above electrophotographic photosensitive member.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on the durability and the like of the electrophotographic photoreceptor. As a result, the surface protective layer has a network structure, particularly a three-dimensional network structure, by crosslinking polymerization of a compound having a specific reactive functional group. And that the specific charge transporting material is present in the network structure in combination, so that an electrophotographic photoreceptor that can sufficiently satisfy the photoreceptor's photoelectric characteristics as well as the mechanical strength can be obtained. As a result, the present invention has been completed.
[0010]
That is,(1) Of the present invention1The electrophotographic photoreceptor is an electrophotographic photoreceptor having at least a photosensitive layer and a surface protective layer provided on a conductive substrate, wherein the surface protective layer comprises a charge transporting material having a hydroxy group, a hydroxy group and fluorine. It is characterized by having a network structure formed by the reaction between the compound having an atom and the isocyanate group-containing compound. Also, this1The method for producing an electrophotographic photoreceptor includes, on a photosensitive layer, a coating solution containing a charge transport material having a hydroxy group, a compound having a hydroxy group and a fluorine atom, and an isocyanate group-containing compound, and then heating. It is characterized in that a surface protective layer is formed by crosslinking polymerization.
[0011]
(2) Of the present invention2The electrophotographic photoreceptor is an electrophotographic photoreceptor having at least a photosensitive layer and a surface protective layer provided on a conductive substrate, wherein the surface protective layer comprises a charge transport material having a hydroxy group, a bisphenol compound and an isocyanate. It has a network structure formed by reaction with a group-containing compound. Also, this2The method for producing an electrophotographic photoreceptor includes coating a coating solution containing a charge transport material having a hydroxy group, a bisphenol compound, and an isocyanate group-containing compound on a photosensitive layer, and then subjecting the surface protective layer to crosslinking polymerization by heating. Is formed.
According to another aspect of the invention, an electrophotographic image forming apparatus includes at least the above-described electrophotographic photosensitive member and a contact charging unit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The above (1) in the present inventionAnd (2)The electrophotographic photoreceptor has a configuration in which at least a photosensitive layer and a surface protective layer are provided on a conductive support, and between the conductive support and the photosensitive layer, if necessary. An undercoat layer can be provided for the purpose of preventing charge injection, improving adhesion, preventing interference fringes, and the like. The photosensitive layer may be a so-called single layer type or a laminated type including a charge generation layer and a charge transport layer. Further, in an electrophotographic photoreceptor including a laminated photosensitive layer (hereinafter, referred to as a “laminated photosensitive body”), the order of lamination of the charge generation layer and the charge transport layer is as follows. May be.
[0013]
In the present invention, the surface protective layer of the electrophotographic photoreceptor is subjected to a cross-linking polymerization reaction using a binding material containing at least a compound having a hydroxy group and a compound having a reactive functional group to form a network structure, particularly a three-dimensional network. A net-like structure is formed, and a charge transport material is bound in the net-like structure.
[0014]
FirstThe surface protective layer of the electrophotographic photoreceptor forms a network-like cross-linked film by a polymerization reaction of a binding material containing a charge transporting material having a hydroxy group, a compound having a hydroxy group and a fluorine atom, and a compound having an isocyanate group. Is what you do.
Also,2The surface protective layer of the electrophotographic photoreceptor forms a network-crosslinked film by a polymerization reaction of a binding material containing a hydroxy group-containing charge transporting material, a bisphenol compound and an isocyanate group-containing compound.
[0015]
As described above, the electrophotographic photoreceptor of the present invention uses a charge transporting material having a hydroxy group and a binding material containing a compound having a functional group capable of forming a bond by reacting with the charge transporting material. By forming the surface protective layer, the photoelectric characteristics can be maintained and the mechanical strength such as abrasion resistance can be provided. In particular, a charge transporting material having at least a plurality of hydroxy groups as a reactive functional group in a side chain and a binding material containing a polyisocyanate compound having a plurality of isocyanate groups as a functional group capable of reacting therewith are used. It is preferable to provide a surface protective layer obtained by a cross-linking polymerization reaction.
[0016]
In the surface protective layer of the present invention, in order to form a three-dimensional network structure by reacting a hydroxy group-containing compound with an isocyanate compound, it is necessary to use an isocyanate compound having three or more functional groups. Thereby, a finely branched structure can be obtained, and a three-dimensional crosslinked film having excellent wear resistance can be formed. On the other hand, when the isocyanate compound having two functional groups is used, the hydroxyl groups are only bonded linearly, and it is difficult to form a three-dimensional network structure.
Since the surface protective layer formed in the present invention forms a three-dimensional network-like bond, the surface protective layer is subjected to strong external stress such as ozone generated in the application of an AC voltage in contact charging or scorotron charging, and the bond is formed. It is considered that the mechanical strength does not suddenly decrease even if is partially cut.
[0017]
Conventionally, the charge transport layer is generally formed by dissolving a charge transport material composed of a low molecular compound in an inert binder resin. Could not be added. Since the surface protective layer of the present invention can form a three-dimensional network structure in the form of a bond by a chemical reaction, it is possible to introduce a larger amount of charge transporting material than a general charge transporting layer, and There is an advantage that the photoelectric characteristics can be maintained.
[0018]
As the charge transporting material having a hydroxy group used in the present invention, a conventionally known charge transporting material having a hydroxy group directly or with an appropriate bonding group interposed therebetween is used. The number of hydroxy groups of the charge transporting material can be any as long as it is one or more. However, in order to form a three-dimensional network structure by crosslinking, a charge transporting material having two or more hydroxy groups is preferable. .
[0019]
As the charge transporting material having a hydroxy group in the present invention, the above-mentioned known materials can be used. However, the compound represented by the following general formula (A) or (B) can be used as a photoreceptor having good photoelectric characteristics and It is particularly preferable because it shows wear resistance.
Embedded image

(Where R₁, R₂And R₃Represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a substituted amino group, and T represents a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may be branched. n is 0 or 1. )
Embedded image

(Wherein, Ar₁And Ar₂Represents a phenyl group or a condensed ring group each of which may be substituted with an alkyl group, a phenyl group, an alkoxy group or an alkyl-substituted phenyl group, and T represents a divalent aliphatic having 1 to 10 carbon atoms which may be branched. Represents a group hydrocarbon group. n is 0 or 1. )
[0020]
Specific examples of T in the compounds represented by the general formulas (A) and (B) are shown below.
Embedded image

[0021]
Embedded image

[0022]
In the compound represented by the general formula (B), Ar₁And Ar₂Specific examples are shown below.
Embedded image

[0023]
Tables 1 and 2 show specific examples of the compound represented by the general formula (A).
[Table 1]

[0024]
[Table 2]

[0025]
Tables 3 to 7 show specific examples of the compound represented by the general formula (B).
[Table 3]

[0026]
[Table 4]

[0027]
[Table 5]

[0028]
[Table 6]

[0029]
[Table 7]

[0031]
In the present invention, the above-mentioned hydroxy groupCharge transport material havingAs the isocyanate group-containing compound used for forming a three-dimensional network structure on the surface protective layer by bonding by a polyaddition reaction with a compound having three or more isocyanate groups. Specifically, 1,3,6-hexamethylene triisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate, 1,8-isocyanate-4-isocyanatomethyloctane, triphenylmethane triisocyanate, tris Polyisocyanate monomers such as (isocyanate phenyl) thiophosphate are used.
[0032]
In addition, among compounds containing three or more isocyanate groups, the compounds obtained from polyisocyanate monomers can be obtained from the viewpoints of film formability of the finally obtained crosslinked film, resistance to crack generation and ease of handling. It is more desirable to use a derivative such as a derivative or a prepolymer. As these examples, particularly preferred are urethane-modified products obtained by modifying a polyol with an excess of an isocyanate compound, buret-modified products obtained by modifying a compound having a urea bond with an isocyanate compound, and allophanate-modified products obtained by adding an isocyanate to a urethane group. Also used are isocyanurate modified products, carbodiimide modified products and the like. Furthermore, although it is included in the above-mentioned modified polyisocyanate, a blocked isocyanate reacted with a blocking agent for temporarily masking the activity of the isocyanate group can also be preferably used. Here, the isocyanate used for the modification may have two functional groups, such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, Examples thereof include xylene diisocyanate, lysine diisocyanate, and tetramethyl xylene diisocyanate.
[0033]
No.1The compound having a hydroxyl group and a fluorine atom used for the surface protective layer of the electrophotographic photoreceptor forms a film by a cross-linking polymerization reaction with an isocyanate compound having 3 or more functional groups together with a charge transporting material having a hydroxy group. The film surface thus obtained has good lubricity and releasability, and thus is effective in preventing paper powder and toner from adhering and sticking to the photoreceptor surface. Examples of the compound having a hydroxy group and a fluorine atom include glycols such as ethylene glycol, propylene glycol, or polyethylene glycol, and hydroxy group-containing compounds such as various polymers or prepolymers having a hydroxy group such as acrylic polyol and polyester polyol. In which the hydrogen atom is replaced by fluorine. Further, these hydroxy group-containing compounds may have a fluorine-substituted alkyl group.
[0034]
As the compound having a hydroxy group and a fluorine atom used in the present invention, fluorine-containing bisphenol derivatives represented by the following C-1 to C-11 are particularly preferred.
Embedded image

[0035]
No.2The bisphenol compound used in the surface protective layer of the electrophotographic photoreceptor is a three-dimensional network with a high crosslinking density by a polyaddition reaction with a polyisocyanate compound having three or more isocyanate groups together with a charge transport material having a hydroxy group. The structure can be easily formed. Therefore, the photoreceptor having the surface protective layer exhibits excellent abrasion resistance, and exhibits extremely high durability even when a strong external stress such as the application of an AC voltage or a discharge gas is applied. . In addition, since the bisphenol compound has excellent compatibility with the charge transport material having a hydroxy group, the bisphenol compound exhibits good photoelectric characteristics because the charge transport material can be uniformly introduced into the network structure. is there.
[0036]
As the bisphenol compound used in the present invention, compounds represented by the following D-1 to D-12 are particularly preferable in terms of abrasion resistance, photoelectric characteristics and the like.
Embedded image

[0037]
In the electrophotographic photoreceptor of the present invention, in order to form a surface protective layer, a coating solution obtained by adding a solvent appropriately selected as necessary to the above-mentioned binder material is coated on the photosensitive layer. A film is formed by crosslinking polymerization.
The mixing ratio of these raw materials is preferably adjusted so that the number of all hydroxy groups and the number of all isocyanate groups are substantially equal. In particular, if an excessive hydroxy group remains in an unreacted state, the hydrophilicity of the surface protective layer increases, and image characteristics may be deteriorated under high temperature and high humidity. Care must be taken with the raw material mixing ratio. Further, the content of the charge transport material in the surface protective layer needs to be determined so that the electrical characteristics of the photoreceptor are maintained and mechanical strength is maintained. Is preferably in the range of 5 to 90% by weight, more preferably 25 to 50% by weight. In the present invention, since the surface protective layer holds the charge transporting material by a chemical bond, more charge transporting materials can be introduced than in the conventional charge transporting layer.
[0038]
Various binder resins may be added to the surface protective layer in the present invention in order to improve its film formability and flexibility. As such a binder resin, a resin having compatibility with the film after the cross-linking polymerization is used. For example, various polymers such as polycarbonate, polyester, acrylics, polyvinyl alcohol, and polyamide are used. However, in order to maintain mechanical strength and photoelectric characteristics, the content of the binder resin in the surface protective layer is preferably set to 60% by weight or less.
[0039]
The cross-linking polymerization reaction for forming the surface protective layer is performed by applying a coating solution having a hydroxy group-containing compound and an isocyanate group-containing compound on the photosensitive layer and then heating. The cross-linking polymerization reaction by the addition of the hydroxy group and the isocyanate group differs depending on the reactivity of the raw material compounds used, but generally it is not necessary to add a catalyst or the like, and it can be carried out only by heating. it can. In order to accelerate this cross-linking polymerization reaction, a catalyst such as an organic metal compound such as dibutyltin dilaurate, an inorganic metal compound, a monoamine, a diamine, a triamine, a cyclic amine, an alcohol amine, or an ether amine is usually used. You may add by the method. When a solvent is used at the time of applying the coating liquid, the heat treatment can be performed simultaneously with or subsequent to the drying step.
[0040]
In the present invention, an antioxidant may be added to the surface protective layer for the purpose of preventing deterioration by an oxidizing gas such as ozone generated in the charger. As the antioxidant, it is preferable to use a hindered phenol-based or hindered amine-based, organic sulfur-based antioxidant, phosphite-based antioxidant, dithiocarbamate-based antioxidant, thiourea-based antioxidant, benzimidazole-based Known substances such as antioxidants can be used. The addition amount of the antioxidant is preferably 15% by weight or less in the surface protective layer, more preferably 10% by weight or less.
[0041]
Examples of the conductive support used in the electrophotographic photoreceptor of the present invention include metals such as aluminum, nickel, chromium, and stainless steel, and aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, and indium oxide. And a plastic film provided with a thin film of ITO or the like, or paper and a plastic film coated or impregnated with a conductivity-imparting agent. These conductive supports are used in an appropriate shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. Further, the surface of the conductive support can be subjected to various kinds of treatments, if necessary, within a range that does not affect the image quality. For example, the surface can be subjected to oxidation treatment, chemical treatment, coloring treatment, or the like, or irregular reflection treatment such as graining.
[0042]
The electrophotographic photoreceptor of the present invention may have an undercoat layer between the conductive support and the photosensitive layer. The undercoat layer prevents the injection of electric charge from the conductive support to the photosensitive layer when the photosensitive layer having the laminated structure is charged, and also serves as an adhesive for integrally bonding and holding the photosensitive layer and the conductive support. It exhibits a function as a layer or, as the case may be, a function of preventing the conductive support from reflecting light.
[0043]
In this undercoat layer, as a binder resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, vinylidene chloride resin, Polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound Known materials such as a titanyl chelate compound, a titanyl alkoxide compound, an organic titanyl compound, and a silane coupling agent are used. These materials can be used alone or as a mixture of two or more kinds, and can also be used as a mixture with fine particles such as titanium oxide, silicon oxide, zirconium oxide, barium titanate, and silicone resin.
The thickness of the undercoat layer is suitably from 0.01 to 10 μm, preferably from 0.05 to 2 μm, and the coating method includes blade coating, wire bar coating, spray coating, and dip coating. Conventional methods such as a bead coating method, an air knife coating method, and a curtain coating method can be used.
[0044]
In the present invention, the charge generation layer of the laminated photoreceptor contains at least a charge generation material and a binder resin. As the charge generation material, amorphous selenium, crystalline selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys, inorganic photoconductive materials such as zinc oxide and titanium oxide, phthalocyanine-based, squarylium-based And organic pigments and dyes such as an anthrone-based, perylene-based, azo-based, anthraquinone-based, pyrene-based, pyrylium salt, and thiapyrylium salt. Among these, from the viewpoint of the photosensitivity of the photoreceptor, it is preferable to use a phthalocyanine-based compound, and examples thereof include metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine. In particular, among phthalocyanine-based compounds, Bragg angles (2θ ± 0.2 °) in the X-ray diffraction spectrum have strong diffraction peaks at 7.4 °, 16.6 °, 25.5 °, and 28.3 °. Chlorogallium phthalocyanine having a specific crystal form, or a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18. Hydroxygallium phthalocyanine having a specific crystal form having strong diffraction peaks at 6 °, 25.1 °, and 28.3 ° has high charge generation efficiency with respect to a wide range of light from visible light to near infrared light. It is particularly preferred because it has. Phthalocyanine crystals having these specific crystal forms are obtained as shown in the following synthesis examples.
[0045]
[Synthesis Example 1]
After putting 30 parts of 1,3-diiminoisoindoline and 9.1 parts of gallium trichloride in 230 parts of quinoline and reacting at 200 ° C. for 3 hours, the product is separated by filtration and washed with acetone and methanol. The obtained wet cake was dried to obtain 28 parts of chlorogallium phthalocyanine crystals. Next, 3 parts of the obtained chlorogallium phthalocyanine crystal was dry-pulverized in an automatic mortar (Lab Mill UT-21 type, manufactured by Yamato Scientific Co., Ltd.) for 3 hours. After milling at room temperature for 24 hours in 20 parts of benzyl alcohol, the glass beads were filtered off, washed with 10 parts of methanol and dried to obtain a Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum. ) Obtained chlorogallium phthalocyanine crystals having strong diffraction peaks at 7.4 °, 16.6 °, 25.5 ° and 28.3 °.
[0046]
[Synthesis Example 2]
After dissolving 3 parts of the chlorogallium phthalocyanine crystal obtained in Synthesis Example 1 in 60 parts of concentrated sulfuric acid at 0 ° C., the solution was dropped into 450 parts of distilled water at 5 ° C. to recrystallize the crystal. The obtained recrystallized product was washed with distilled water, dilute aqueous ammonia and the like, and then dried to obtain 2.5 parts of hydroxygallium phthalocyanine crystals. The crystals were milled for 5.5 hours in an automatic mortar, and 0.5 parts thereof were milled together with 15 parts of dimethylformamide and 30 parts of glass beads (1 mmφ) for 24 hours. The obtained crystals were separated and separated with methanol. After washing and drying, the Bragg angles (2θ ± 0.2 °) in the X-ray diffraction spectrum are 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °. , 25.1 ° and 28.3 °, hydroxygallium phthalocyanine crystals having strong diffraction peaks were obtained.
[0047]
As the binder resin of the charge generation layer, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal resin, polycarbonate resin, polyester resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate A copolymer, a silicone resin, a phenol resin, a poly-N-vinyl carbazole resin, or the like is used, but is not limited thereto. These binder resins can be used alone or in combination of two or more.
[0048]
The compounding ratio (weight ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10. The thickness of the charge generation layer used in the present invention is generally 0.1 to 5 μm, preferably 0.2 to 2.0 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.
[0049]
Further, as a solvent used for forming the charge generation layer, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, Ordinary organic solvents such as tetrahydrofuran, methylene chloride and chloroform can be used alone or in combination of two or more.
[0050]
Further, the charge transport layer of the multilayer photoconductor of the present invention contains at least a charge transport material and a binder resin. This charge transport layer may be either a low molecular weight dispersion type charge transport layer or a polymer charge transport layer having a charge transport function itself. Examples of the charge transport material include quinone-based compounds such as p-benzoquinone, chloranil, bromoanil, and anthraquinone; tetracyanoquinodimethane-based compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone-based compounds; and benzophenone-based compounds. , Electron-withdrawing substances such as cyanovinyl compounds, ethylene compounds, etc., triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. These charge transport materials can be used alone or in combination of two or more.
[0051]
Benzidine-based compounds represented by the following general formula (a) and triphenylamine-based compounds represented by the following general formula (b) as charge transport materials in the present invention have high charge (hole) transport ability and excellent stability. Since it has properties, it is used as a particularly preferable one. These may be used alone or as a mixture.
[0052]
Embedded image

(Where R₄And R₅May be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. R₆, R₇, R₈And R₉May be the same or different, and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an amino group substituted with an alkyl group having 1 to 2 carbon atoms. Show. p and q are 1 or 2. )
[0053]
Embedded image

(Where R₁₀Represents a hydrogen atom or a methyl group. Ar₃And Ar₄Represents a substituted or unsubstituted aryl group, and the substituent of the substituted aryl group is a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 3 carbon atoms. Is an amino group substituted with m is 1 or 2. )
[0054]
Tables 8 to 10 show specific examples of the compound represented by the general formula (a).
[Table 8]

[0055]
[Table 9]

[0056]
[Table 10]

[0057]
Tables 11 to 13 show specific examples of the compound represented by the general formula (b).
[Table 11]

[0058]
[Table 12]

[0059]
[Table 13]

[0060]
Examples of the binder resin for the charge transport layer include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, and vinylidene chloride-acrylonitrile copolymer. Copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-acrylic resin, styrene-alkyd resin, poly-N -Known resins such as vinyl carbazole and polysilane can be used.
[0061]
Further, an antioxidant used for the surface protective layer described above may be added to the charge transport layer. Since the charge transport layer is not the outermost layer, it does not come into direct contact with the oxidizing gas.However, since such an oxidizing gas may penetrate the surface protective layer and penetrate into the charge transport layer, this is prevented. Used as appropriate. As the specific examples of the antioxidant, the same ones as described above are used, and the addition amount thereof is also 15% by weight or less, preferably 10% by weight or less.
[0062]
Examples of the solvent for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride. Organic solvents such as cyclic or linear ethers such as tetrahydrofuran, ethyl ether and dioxane are used alone or in combination of two or more.
[0063]
In the electrophotographic photoreceptor of the present invention, in the case of a single-layer type photosensitive layer, the photosensitive layer is formed using at least the above-described charge generating substance and a binder resin. As the binder resin, those similar to the binder resins used for the charge generation layer and the charge transport layer described above are used. The content of the charge generating substance in the single-layer type photosensitive layer is 10 to 85% by weight, preferably 20 to 50% by weight. If necessary, an antioxidant may be added to the single-layer type photosensitive layer for the same reason as in the case of the charge transport layer. The amount of the antioxidant is 15% by weight or less, preferably 10% by weight. It is as follows. In addition, the above-described charge transporting material may be added to the single-layer type photosensitive layer for the purpose of improving the photoelectric characteristics and the like. In this case, the addition amount is 70% by weight or less, and preferably 50% by weight or less.
[0064]
The image forming apparatus of the present invention includes at least the electrophotographic photoreceptor described above, and a charging unit for charging the photoreceptor to a predetermined surface potential, an exposing unit for forming an electrostatic latent image, and an electrostatic latent image. It has a developing means for visualizing, a transferring means for transferring the developing material on the photoreceptor to paper or the like as appropriate. The electrophotographic photoreceptor of the present invention can be used as a charging unit in a non-contact charging type image forming apparatus such as a scorotron, and even in this case, it has excellent photoelectric characteristics and durability, particularly ozone resistance. is there. Further, when used in a contact charging type image forming apparatus such as a charging roll as a charging means, it is possible to exhibit excellent durability against abrasion of the photoreceptor which is conspicuous in contact charging.
[0065]
FIG. 1 shows an example of an image forming apparatus using the electrophotographic photoreceptor of the present invention, in which a charger 3 such as a charging roll to which a voltage is supplied from a power supply 2 provided outside the apparatus is used. The photosensitive drum 1 is provided so as to be in contact therewith. Further, around the photosensitive drum 1, an image input device 4 such as a laser exposure optical system, a developing device 5 loaded with a magnetic one-component toner or the like, a transfer device 6 such as a pressure transfer device or an electrostatic transfer device, a cleaner device 8. An exposing unit 10 such as an LED array for eliminating static electricity is provided. Reference numeral 7 denotes a sheet, and 9 denotes a fixing device. In the image forming apparatus of the present invention, in order to charge the photosensitive drum 1 by contact charging using a charging roll, which is a conductive member, as the charger 3, a DC voltage and an AC voltage are applied to the charging roll. The image is formed by superimposing.
[0066]
As the shape of the conductive member that performs contact charging, any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like can be used, and a roller-shaped member is particularly preferable. This roller-shaped member is usually composed of a resistance layer, an elastic layer and a core material for supporting the resistance layer in this order from the outside of the roller, and a protection layer can be provided outside the resistance layer as needed. The material of the core material has conductivity, and usually, iron, copper, brass, stainless steel, aluminum, nickel or the like is used. Further, a resin molded product or the like in which other conductive particles or the like are dispersed can be used. The elastic layer is made of a material having conductivity or semi-conductivity. Usually, a material in which conductive particles or semi-conductive particles are dispersed in a rubber material is used. As the rubber material, EPDM, polybutadiene, natural rubber, polyisobutylene, SBR, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer, norbornene rubber, fluorosilicone rubber, ethylene oxide rubber, etc. are used. . Examples of the conductive particles or semiconductive particles include metals such as carbon black, zinc, aluminum, copper, iron, nickel, chromium, and titanium, and ZnO-Al₂O₃, SnO₂-Sb₂O₃, In₂O₃-SnO₂, ZnO-TiO₂, MgO-Al₂O₃, FeO-TiO₂, TiO₂, SnO₂, Sb₂O₃, In₂O₃, ZnO, MgO, and other metal oxides can be used, and these materials can be used alone or as a mixture of two or more kinds. When two or more kinds are used, one of them may be fine particles. As the fine particles, fine particles of a fluororesin are used.
[0067]
The material of the resistance layer and the protective layer of the roller-shaped member is obtained by dispersing conductive particles or semi-conductive particles in a binder resin and controlling the resistance value.³-10¹⁴Ω · cm, preferably 10⁵-10¹²Ω · cm, more preferably 10⁷-10¹²Ω · cm is used. Further, their film thickness is 0.01 to 1000 μm, preferably 0.1 to 500 μm, more preferably 0.5 to 100 μm. Examples of the binder resin include acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, vinyl chloride resin, polyarylate resin, polythiophene resin, and PFA. Polyolefin resins, such as FEP, PET, etc., and styrene-butadiene resins are used. As the conductive particles or semiconductive particles, the same carbon black, metal, and metal oxide as those of the elastic layer are used.
[0068]
If necessary, an antioxidant such as hindered phenol or hindered amine, a filler such as clay or carion, or a lubricant such as silicone oil can be added to the above-mentioned materials. In order to form these layers, conventional coating methods such as blade coating method, Meyer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, vacuum deposition method, plasma coating method, etc. A method can be used.
[0069]
In order to charge the electrophotographic photoreceptor using these conductive members, a voltage is applied to the conductive members, and the applied voltage is preferably a DC voltage with an AC voltage superimposed thereon. It is difficult to obtain a uniform charge. As the range of the voltage to be used, the DC voltage is preferably in a positive or negative range of 50 to 2000 V, and particularly preferably 100 to 1500 V. The AC voltage to be superimposed has a peak-to-peak voltage in the range of 400 to 1800 V, preferably 800 to 1600 V, and more preferably 1200 to 1600 V. The frequency of the AC voltage is in the range of 50 to 20000 Hz, preferably 100 to 2000 Hz.
[0070]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Note that “parts” means “parts by weight”.
Example 1
A solution consisting of 10 parts of a zirconium compound (Orgatic ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.), 1 part of a silane compound (A1110, manufactured by Nippon Unicar), 40 parts of isopropanol and 20 parts of butanol was applied on an aluminum pipe by dip coating. At 150 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.1 μm.
Next, 1 part of an X-type metal-free phthalocyanine crystal and 1 part of polyvinyl butyral (Eslec BM-S, manufactured by Sekisui Chemical Co., Ltd.) were mixed with 100 parts of cyclohexanone, dispersed with glass beads by a sand mill for 1 hour, and then subjected to the above undercoating. The layer was dip-coated and then heated at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.
Next, 2 parts of a benzidine compound shown as an exemplary compound (No. 27) in Table 9 and 3 parts of a polymer compound (viscosity average molecular weight 39000) comprising a repeating structural unit represented by the following structural formula (E) were prepared. A coating solution dissolved in 20 parts of chlorobenzene was applied on the charge generation layer by a dip coating method, and heated at 110 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm.
[0071]
Embedded image

[0072]
Next, as a charge transporting material having a hydroxy group, 3 parts of the exemplary compound (A-1) in Table 1, A compound having a hydroxy group and a fluorine atom, 1 part of exemplified compound (C-3), and a compound having an isocyanate groupBullet-modified polyisocyanate shown in (F) below(Solid content about 60% by weight) 4.7 partsIs cyclohexanone30Dissolve in the part,The resulting solutionOnAfter spray coating on the charge transport layer and drying at room temperature for 10 minutes,150By heating at 60 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm, an electrophotographic photosensitive member was produced.
Embedded image

[0073]
The electrophotographic photosensitive member obtained as described above was mounted on an XP-11 modified machine manufactured by Fuji Xerox Co., Ltd., and the following experiment was performed. This XP-11 remodeling machine is an electrophotographic printer having a contact charging device using a charging roll, a laser exposure optical system, a developing device, a transfer corotron, a charge removing LED, a cleaning blade, and a fixing roll as shown in FIG. is there.
Using this image forming apparatus, the image quality of the initial image and the image quality after the continuous copy printing test of 50,000 sheets were evaluated. The film thickness before and after the test was measured, and the amount of decrease in the film thickness was defined as the amount of wear. The charging was performed by charging the charging roll with DC-550V and AC 1.5kV._PP(800 Hz) was applied by applying a charging voltage superimposed thereon.
[0074]
Comparative Example 1
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the thickness of the charge transport layer was 25 μm and no surface protective layer was provided.Was.
[0082]
Comparative example2
Example1Similarly, a subbing layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 3 parts of the exemplified compound (A-1) as a charge transporting material having a hydroxy group, 1.5 parts of a compound in which a fluorine atom of the exemplified compound (C-3) is replaced with hydrogen, and (F) as an isocyanate group-containing compound ) 4.7 parts were dissolved in 25 parts of cyclohexanone, and the obtained solution was spray-coated on the charge transport layer, dried at room temperature for 10 minutes, and then heated at 150 ° C for 60 minutes to form a film having a thickness of 5 µm. An electrophotographic photosensitive member was produced by forming a surface protective layer of
[0083]
ratioComparative Example 1 and Comparative Example2An experiment using the above-described XP-11 modified machine was performed on the electrophotographic photoreceptor obtained in the same manner as in the electrophotographic photoreceptor obtained in Example 1. In addition, neutral paper manufactured by Fuji Xerox Co., Ltd. was used as copy printing paper. Further, in order to evaluate the surface lubricity of the photoreceptor, a continuous copy printing test of 10,000 sheets was performed using acidic paper, and the effect of adhesion of paper powder and the like to the photoreceptor surface was evaluated. These results are tabulated.14Shown in
[0084]
[Table 14]

[0085]
table14As shown in the above, in the continuous copy printing test using acid paper,1No problem occurred with the photoconductor ofIn the case of Comparative Example 1, the photoelectric characteristic was changed due to a large amount of abrasion, and the image quality density was lowered because the surface potential was not sufficiently lowered. Further, streaky scratches were frequently generated on the surface due to contact with a developer or paper. However, this appears as an image quality defect. Also,Comparative example2The image defect due to the adhesion of paper powder (talc) was remarkable. This indicates that the inclusion of a compound having a hydroxy group and a fluorine atom in the surface protective layer is effective in preventing the deterioration of image quality due to the adhesion of foreign matter to the photoreceptor surface.
[0086]
Example2~4
Example1In the following, as a charge transporting material having a hydroxy group used for forming the surface protective layer, the following tableFifteenExample except that the one shown in1An electrophotographic photoreceptor was prepared in the same manner as described above, and continuous copy printing of 50,000 sheets was performed.
[0087]
[Table 15]

[0088]
Example5
In the same manner as in Example 1, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 2 parts of the exemplified compound (B-19) as a charge transporting material having a hydroxy group, 1 part of the exemplified compound (C-3), and 3 parts of the above (F) as an isocyanate group-containing compound are dissolved in 30 parts of cyclohexanone. The resulting solution is spray-coated on the charge transport layer, dried at normal temperature for 10 minutes, and then heated at 150 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm, thereby forming an electrophotographic photoreceptor. Was prepared.
[0089]
Example6~7
Example5In place of Exemplified Compound (B-19), the following table16Example except that the one shown in5An electrophotographic photoreceptor was prepared in the same manner as described above, and the same evaluation was performed.
Example8~10
Example1In the above, as the compound having a hydroxy group and a fluorine atom used for the surface protective layer, the following table was used in place of the exemplified compound (C-3)16Example except that the one shown in1An electrophotographic photoreceptor was prepared in the same manner as described above, and the same evaluation was performed.
[Table 16]

[0090]
Example2~10Table showing the evaluation results obtained in17Shown in
[Table 17]

[0091]
Example11
In the same manner as in Example 1, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 1 part of the exemplified compound (A-1) as the charge transporting material having a hydroxy group, 1 part of the exemplified compound (D-1) as a bisphenol compound, and the burette-modified polyisocyanate shown in the above (F) as the isocyanate group-containing compound (Solid content: about 67% by weight) 3 parts were dissolved in 10 parts of cyclohexanone, and the obtained solution was spray-coated on the charge transport layer, dried at room temperature for 10 minutes, and then heated at 150 ° C. for 60 minutes. Then, a 5 μm-thick surface protective layer was formed to produce an electrophotographic photosensitive member.
[0092]
Comparative example3
Example11Similarly, a subbing layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 3 parts of the exemplified compound (D-1) as a bisphenol compound and 4 parts of the above (F) as an isocyanate group-containing compound are dissolved in 15 parts of xylene, and the obtained solution is spray-coated on the charge transport layer. Then, after drying at room temperature for 10 minutes, heating at 150 ° C. for 60 minutes to form a 5 μm-thick surface protective layer having only a three-dimensional crosslinked network structure, which does not include a charge transporting material. A photoreceptor was prepared.
[0093]
Comparative example4
Example11Similarly, a subbing layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 2 parts of the exemplified compound (A-1) as a charge transport material having a hydroxy group, 2 parts of the exemplified compound (D-1) as a bisphenol compound, and 4,4'-diphenylmethane diisocyanate having 2 functional groups as an isocyanate group-containing compound 3 parts are dissolved in 10 parts of xylene, and the obtained solution is spray-coated on the charge transport layer, dried at room temperature for 10 minutes, and then heated at 150 ° C. for 60 minutes to form a 5 μm-thick surface protective layer. Was formed to produce an electrophotographic photosensitive member.
Example11, Comparative Example 1,3as well as4An experiment using the above-described XP-11 modified machine was performed on the electrophotographic photoreceptor obtained in the same manner as in the electrophotographic photoreceptor obtained in Example 1. Table of these evaluation results18Shown in
[Table 18]

[0094]
Example11Using the electrophotographic photoreceptor obtained in the above, the image quality characteristics of the initial image were good, and the good image quality characteristics were maintained even after copying 50,000 sheets. The reason why the initial image quality is good is that the surface protective layer contains a charge transport material, and thus the photoconductor has excellent photoelectric characteristics. This indicates that the comparative example does not include the charge transport material in the surface protective layer.3It is also evident from the comparison with the photoconductor. The reason why the excellent image quality characteristics are maintained even after 50,000 copies have been made is that the wear amount of the photoreceptor is small and the surface of the photoreceptor is hardly damaged at the same time. On the other hand, after 50,000 copies, the comparative example4In the case of (1), the amount of wear was large, and streaky scratches were frequently generated on the surface, which appeared as image defects. From this, it is effective to use a binding material having a functional group number of 3 or more as a constituent material of the surface protective layer to form a three-dimensional network structure having a high cross-linking density and to impart durability to AC voltage application in contact charging. You can see that there is.
[0095]
Example12~14
Example11In the following, as a charge transport material having a hydroxy group used for the surface protective layer, the following table19Example except that the one shown in11An electrophotographic photoreceptor was prepared in the same manner as described above, and the same evaluation was performed.
[0096]
ExampleFifteen
Example11Similarly, a subbing layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum pipe.
Next, 2 parts of the exemplified compound (B-19) as a charge transporting material having a hydroxy group, 1 part of the exemplified compound (D-1) as a bisphenol compound, and 3 parts of the polyisocyanate (F) as an isocyanate group-containing compound, After dissolving in 10 parts of a mixed solvent of cyclohexanone and xylene (weight ratio: 1: 2), the obtained solution is spray-coated on the charge transport layer, dried at room temperature for 10 minutes, and then dried at 150 ° C. for 60 minutes. After heating for 5 minutes to form a surface protective layer having a thickness of 5 μm, an electrophotographic photosensitive member was produced.
[0097]
Example16~17
ExampleFifteenIn the following, as a charge transport material having a hydroxy group used for the surface protective layer, the following table19Example except that the one shown inFifteenAn electrophotographic photoreceptor was prepared in the same manner as described above, and the same evaluation was performed.
[Table 19]

[0098]
Example18~19
Example11In Table 2, as a bisphenol compound used for the surface protective layer,20Example except that the one shown in11An electrophotographic photoreceptor was prepared in the same manner as described above, and the same evaluation was performed.
[Table 20]

[0099]
Example12~19The evaluation results of the electrophotographic photoreceptor obtained in21Shown in
[Table 21]

[0103]
【The invention's effect】
Since the surface protective layer of the electrophotographic photoreceptor of the present invention is formed of a material having a three-dimensional network structure including a charge transport material, it has good photoelectric properties and excellent mechanical strength such as excellent abrasion resistance. In addition, it has high durability against strong external stress such as the application of an AC voltage and a discharge gas. Therefore, the image forming apparatus using the electrophotographic photoreceptor can maintain good quality images even after copying a large number of sheets.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view illustrating an example of an image forming apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 2 ... Power supply, 3 ... Charger, 4 ... Image input device, 5 ... Developing device, 6 ... Transfer device, 7 ... Paper, 8 ... Cleaner device, 9 ... Fixing device, 10 ... Exposure remover .

Claims (12)

In an electrophotographic photoreceptor having at least a photosensitive layer and a surface protective layer provided on a conductive substrate, the surface protective layer comprises a charge transporting material having a hydroxy group, a compound having a hydroxy group and a fluorine atom, and a compound having an isocyanate group. An electrophotographic photosensitive member having a network structure formed by the reaction with In an electrophotographic photosensitive member having at least a photosensitive layer and a surface protective layer provided on a conductive substrate, the surface protective layer is formed by a reaction between a charge transporting material having a hydroxy group, a bisphenol compound, and an isocyanate group-containing compound. An electrophotographic photoreceptor, characterized in that the electrophotographic photoreceptor has a closed network structure. 3. The electrophotographic photoreceptor according to claim 1, wherein the charge transporting material having a hydroxy group is represented by the following general formula (A) or (B).

(Where R _One , R _Two And R _Three Represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a substituted amino group, and T represents a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may be branched. n is 0 or 1. )

(Wherein, Ar _One And Ar _Two Represents a phenyl group or a condensed ring group, each of which may be substituted with an alkyl group, a phenyl group, an alkoxy group or an alkyl-substituted phenyl group, and T is a divalent group having 1 to 10 carbon atoms which may be branched. Shows an aliphatic hydrocarbon group. n is 0 or 1. ) The electrophotographic photoreceptor according to claim 1 or 2, wherein at least one of the isocyanate group-containing compounds is a polyisocyanate having 3 or more functional groups. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the network structure of the surface protective layer is formed in an inert binder resin.   The electrophotographic photoconductor according to any one of claims 1 to 5, wherein the photosensitive layer contains hydroxygallium phthalocyanine or chlorogallium phthalocyanine. The photosensitive layer contains a benzidine-based compound represented by the following general formula (a) and / or a triphenylamine-based compound represented by the following general formula (b). 8. The electrophotographic photosensitive member according to any one of the above.

(Where R _Four And R _Five May be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. R ₆ , R ₇ , R ₈ And R ₉ May be the same or different, and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an amino group substituted with an alkyl group having 1 to 2 carbon atoms. Show. p and q are 1 or 2. )

(Where R _Ten Represents a hydrogen atom or a methyl group. Ar _Three And Ar _Four Represents a substituted or unsubstituted aryl group, and the substituent of the substituted aryl group is a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 3 carbon atoms. Is an amino group substituted with m is 1 or 2. ) A surface protective layer is formed on the photosensitive layer by applying a coating solution containing a charge transporting material having a hydroxy group, a compound having a hydroxy group and a fluorine atom, and an isocyanate group-containing compound, followed by crosslinking polymerization by heating. The method for producing an electrophotographic photoreceptor according to claim 1, wherein: The surface protective layer is formed by applying a coating solution containing a charge transporting material having a hydroxy group, a bisphenol compound, and an isocyanate group-containing compound onto the photosensitive layer, and then performing crosslinking polymerization by heating. The method for producing an electrophotographic photosensitive member according to claim 2. The method for producing an electrophotographic photoreceptor according to claim 8, wherein the coating liquid for forming the surface protective layer contains a solvent. An electrophotographic image forming apparatus having at least an electrophotographic photosensitive member and a charging unit for charging the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 7, An image forming apparatus, wherein the charging means is contact charging. The image forming apparatus according to claim 11, wherein the applied voltage used for contact charging has an AC component.

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