JP3773136B2 - Electrophotographic photoreceptor - Google Patents

Description

【０００７】
｛式中、Ａｒ¹ およびＡｒ² の少なくとも１つは下記一般式（II）または（ III ）で示される基を表わす。
【０００８】
【化５】

【０００９】
Ａｒ¹ およびＡｒ² が一般式（II）および（ III ）以外の場合は、置換基を有していても良いアルキル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアリール基、置換基を有していてもよい複素環基または置換基を有していてもよい縮合多環基を表わす（但し、置換基を有していてもよい縮合多環基として、一般式 (IV) は除く。この一般式 (IV) の式中、Ｃ，Ｄは結合して置換基を有していてもよいナフタレン環を表わす。ＣおよびＤは、更に、環構造を形成する２価の残基Ｚ ³ を含む縮合環を有している。）。Ａｒ³ は置換基を有していてもよいアリーレン基、置換基を有していてもよい二価の複素環基、置換基を有していてもよい二価の縮合多環基または置換基を有していてもよいビフェニレン基を表わす。Ｒ¹ ，Ｒ² ，Ｒ³ およびＲ⁴ は夫々独立して、水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアリール基、置換基を有していてもよい複素環基または置換基を有していてもよい縮合多環基を表わす。Ｒ⁵ は置換基を有していてもよいアリール基、置換基を有していてもよい複素環基または置換基を有していてもよい縮合多環基を表わす。ｎは０または１〜５の整数を表わし、ｎが２以上の時、それぞれのＲ³ およびＲ⁴ は同一でも異なっていてもよい。
【００１０】
一般式（II）および（ III ）の式中、ＡおよびＢは、それぞれ置換基を有していてもよいベンゼン環を表わす。ＡおよびＢは、更に、それぞれ環構造を形成する２価の残基Ｚ¹ またはＺ ² を含む縮合環を有している。Ｒ⁶ ，Ｒ⁷ ，Ｒ⁸ ，Ｒ⁹ ，Ｒ¹⁰およびＲ¹¹は、それぞれ独立して、水素原子、ハロゲン原子、水酸基、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアリール基または置換基を有していてもよい複素環基を表わす。Ａｒ¹ およびＡｒ² が一般式（II）および（ III ）以外の場合、Ａｒ¹ とＡｒ³ およびＡｒ² とＡｒ³ は直接または結合基を介して連結していてもよく、また、Ｒ² とＲ⁵ （ｎ＝０の時）およびＲ⁴ とＲ⁵（ｎ＝１〜５の時）は直接または結合基を介して連結していてもよい。｝
【００１１】
以下、本発明を詳細に説明する。
本発明の電子写真用感光体は、感光層中に前記一般式（Ｉ）で表されるスチルベン系化合物を含有するものである。前記一般式（Ｉ）に於て、Ａｒ¹ およびＡｒ² の少くとも１つは前記一般式（II），（III ）または（IV）で示される基を表わす。一般式（II）〜（IV）において、ＡおよびＢはそれぞれ置換基を有していてもよいベンゼン環を表わし、ＣとＤは結合して置換基を有していてもよいナフタレン環を表わし、それらの置換基としては、水素原子；水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等の炭素数１〜８程度のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基；ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
Ａ，Ｂ，ＣおよびＤは更にそれぞれ環構造を形成する２価の残基Ｚ¹ ，Ｚ² またはＺ³ を含む縮合環を有している。（II），（III ），（IV）式で表される基としては、例えば下記一般式（VI）〜（XV）が挙げられる。
【００１２】
【化６】

【００１３】
上記一般式（VI）〜（XV）においてＸおよびＹは置換基を１ケ以上有していてもよいベンゼン環を表わし、その置換基としてはＡ〜Ｄの置換基として例示したものが挙げられる。
Ａｒ¹ およびＡｒ² は一般式（II），（III ）および（IV）以外の場合は、メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等の炭素数１〜８程度のアルキル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基、フェニル基、ナフチル基等のアリール基；チエニル基、フリル基、ピリジル基等の複素環基；ピレニル基、アントラセニル基、フルオレニル基等の縮合多環基を表わす。これらのアルキル基、アラルキル基、アリール基、複素環基および縮合多環基は置換基を有していてもよく、その置換基としては、水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基、ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００１４】
好ましくはＡｒ¹ およびＡｒ² の少なとも１つが一般式（II）または（IV）で示される基である。
Ａｒ³ はフェニレン基、ナフチレン基等のアリーレン基；チエニレン基、フリレン基、ピリジレン基等の二価の複素環基；ピレニレン基、アントラセニレン基、フルオレニレン基等の二価の縮合多環基；ビフェニレン基を表わし、特にアリーレン基、二価の縮合多環基およびビフエニレン基が好ましい。これらのアリーレン基、二価の複素環基、二価の縮合多環基、ビフェニレン基は、置換基を有していてもよく、置換基としては、水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基、ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００１５】
Ｒ¹ ，Ｒ² ，Ｒ³ およびＲ⁴ は、それぞれ、水素原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等の炭素数１〜８程度のアルキル基；フェニル基、ナフチル基等のアリール基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；チエニル基、フリル基、ピリジル基等の複素環基；ピレニル基、アントラセニル基、フルオレニル基等の縮合多環基を表わし、これらは、互いに同一でも異なっていてもよい。これらのアルキル基、アリール基、アラルキル基、複素環基、縮合多環基は、置換基を有していてもよく、置換基としては、水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基、ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００１６】
Ｒ⁵ はフェニル基、ナフチル基等のアリール基；チエニル基、フリル基、ピリジル基等の複素環基；ピレニル基、アントラセニル基、フルオレニル基等の縮合多環基を表わす。これらのアリール基、複素環基および縮合多環基は置換基を有していてもよく、置換基としては、水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基、ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００１７】
ｎは０または１〜５の整数を表わし、ｎが２以上の時、それぞれのＲ³ は互いに同一でも異なっていてもよく、それぞれのＲ⁴ は互いに同一でも異なっていてもよい。
前記一般式（II），（III ）および（IV）においてＲ⁶ ，Ｒ⁷ ，Ｒ⁸ ，Ｒ⁹ ，Ｒ¹⁰およびＲ¹¹はそれぞれ水素原子；塩素原子、臭素原子、沃素原子等のハロゲン原子；水酸基；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等の炭素数１〜８程度のアルキル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基、ピリジル基等の複素環基を表わし、これらは互いに同一でも異なっていてもよい。これらのアルキル基、アラルキル基、アリール基、複素環基は置換基を有していてもよく、置換基としては、水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基；ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００１８】
またＡｒ¹ およびＡｒ² が一般式（II），（III ）および（IV）以外の場合、Ａｒ¹ とＡｒ³ またはＡｒ² とＡｒ³ は直接または結合基を介して連結していてもよい。例えば以下の一般式（XVI ），（XVII），（VXIII ），（XIX ）および（XX）で表される構造をとることができる。
【００１９】
【化７】

【００２０】
また、一般式（Ｉ）中、Ｒ² とＲ⁵ （ｎ＝０の時）およびＲ⁴ とＲ⁵ （ｎ＝１以上の時）は直接または結合基を介して連結していてもよく、例えば以下の一般式（XXI ），（XXII），（XXIII ），（XXIV），（XXV ），（XXVI），（XXVII ），（XXVIII）および（XXIX）で表される構造をとることができる。
【００２１】
【化８】

【００２２】
上記一般式（XVI ）〜（XXIX）においてＸおよびＹは置換基を１個以上有してもよいベンゼン環を表わし、その置換基としては水素原子；水酸基；塩素原子、臭素原子、沃素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等のアルキル基；メトキシ基、エトキシ基、ブトキシ基等のアルコキシ基；アリル基；ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基；フェノキシ基、トリロキシ基等のアリールオキシ基；ベンジルオキシ基、フェネチルオキシ基等のアラルキルオキシ基；フェニル基、ナフチル基等のアリール基；チエニル基、フリル基等の複素環基；スチリル基、ナフチルビニル基等のアリールビニル基；ジメチルアミノ基、ジエチルアミノ基等のジアルキルアミノ基；ジフェニルアミノ基、ジナフチルアミノ基等のジアリールアミノ基；ジベンジルアミノ基、ジフェネチルアミノ基等のジアラルキルアミノ基；ジチエニルアミノ基、ジフリルアミノ基等のジ複素環アミノ基；ジアリルアミノ基；上記のアミノ基を組み合わせたジ置換アミノ基；ニトロ基；アセチル基、ベンゾイル基等のアシル基等があげられる。
【００２３】
一般式（Ｉ）で示されるスチルベン系化合物の中、特に好ましい化合物としては、Ａｒ¹ およびＡｒ² の少くとも１つが一般式（II）または一般式（IV）の基、Ａｒ³ がアリーレン基、縮合多環基またはビフェニル基、ｎが０または１の化合物である。特に、一般式（II）の基としては前示（VI）式の基が、また一般式（IV）の基としては前示（XIV ）式の基が好ましい。
前記一般式（Ｉ）で表されるスチルベン系化合物は、例えば、下記に示す様にホスホン酸ジエチルとカルボニル化合物とのＷｉｔｔｉｇ−Ｈｏｒｎｏｒ−Ｅｍｍｏｎｓ反応を利用して製造することが出来る。
【００２４】
【化９】

【００２５】
（式中、Ａｒ¹ ，Ａｒ² ，Ａｒ³ ，Ｒ¹ ，Ｒ² ，Ｒ³ ，Ｒ⁴ およびＲ⁵ は一般式（Ｉ）と同じ意味を有する。Ｒ¹²はアルキル基を表わす。）
すなわち一般式（XXX ）または一般式（XXXI）のカルボニル化合物と一般式（XXXII ）のホスホン酸ジエステルをテトラヒドロフラン、１，２−ジメトキシエタン、Ｎ，Ｎ−ジメチルホルムアミド等の溶媒中で、ポタシウムアルコキシド、ソジウムアルコキシド、水素化ナトリウム等の塩基の存在下反応させることにより一般式（Ｉ）の化合物が得られる。反応後、要すれば再結晶、カラムクロマトグラフィー等の公知の手段により精製すれば高純度の目的物が得られる。
【００２６】
なお、一般式（Ｉ）の化合物には炭素−炭素二重結合に基づく位置異性体が存在する。上述の方法により得られた化合物はシス体、トランス体の混合物である。なお、本明細書に於ては、一般式（Ｉ）の化合物は特記しない限り、シス体、トランス体の混合物を意味する。
一般式（Ｉ）で示されるスチルベン系化合物の具体例を以下に例示するが、本発明は以下の化合物に限定されるものではない。
【００２７】
【化１０】

【００２８】
【化１１】

【００２９】
【化１２】

【００３０】
【化１３】

【００３１】
【化１４】

【００３２】
【化１５】

【００３３】
【化１６】

【００３４】
【化１７】

【００３５】
【化１８】

【００３６】
一般式（Ｉ）で表されるスチルベン系化合物は有機光導電体としてきわめて優れた性能を示す。特に電荷輸送剤として用いられた場合には高感度で耐久性に優れた感光体を与える。
電子写真用感光体の感光層の形態としては種々のものが知られているが、本発明の電子写真用感光体の感光層としてはそのいずれであってもよい。例えばバインダー中にスチルベン系化合物と必要に応じ増感剤となる色素や電子吸引性化合物を添加した感光層、光を吸収すると極めて高い効率で電荷キャリアーを発生する電荷発生剤粒子とスチルベン系化合物をバインダー中に添加した感光層、スチルベン系化合物とバインダーからなる電荷輸送層と光を吸収する極めて高い効率で電荷キャリアーを発生する電荷発生剤粒子からなるあるいはこれとバインダーからなる電荷発生層を積層した感光層等が挙げられる。
【００３７】
これらの感光層中には、一般式（Ｉ）で表されるスチルベン系化合物と共に、有機光導電体としてすぐれた性能を有する公知の他のアリールアミン化合物、ヒドラゾン化合物、スチルベン系化合物等を混合してもよい。
本発明においては上記一般式（Ｉ）で表されるスチルベン系化合物を電荷発生層と電荷輸送層の２層からなる感光層の電荷輸送層中に用いる場合に、特に感度が高く残留電位が小さく、かつ、繰り返し使用した場合に、表面電位の変動や感度の低下、残留電位の蓄積等が少なく耐久性に優れた感光体を得ることができる。
【００３８】
本発明の電子写真用感光体は常法に従って上記一般式（Ｉ）で表されるスチルベン系化合物をバインダーと共に適当な溶剤中に溶解し、必要に応じ光を吸収すると極めて高い効率で電荷キャリアーを発生する電荷発生剤粒子、増感染料、電子吸引性化合物、あるいは、可塑剤、顔料その他の添加剤を添加して得られる塗布液を導電性支持体上に塗布、乾燥し、通常、数ミクロン〜数十ミクロン、好ましくは１０ミクロン〜４０ミクロンの膜厚の感光層を形成させることにより製造することができる。電荷発生層と電荷輸送層の二層からなる感光層の場合は、電荷発生層の上に上記塗布層を塗布するか、上記塗布液を塗布して得られる電荷輸送層の上に電荷発生層を形成させることにより、製造することができる。
【００３９】
塗布液調製用の溶媒としては、テトラヒドロフラン、１，４−ジオキサン等のエーテル類；メチルエチルケトン、シクロヘキサノン等のケトン類；トルエン、キシレン等の芳香族炭化水素類；Ｎ，Ｎ−ジメチルホルムアミド、アセトニトリル、Ｎ−メチルピロリドン、ジメチルスルホキシド等の非プロトン性極性溶媒；酢酸エチル、蟻酸メチル、メチルセロソルブアセテート等のエステル類；ジクロロエタン、クロロホルム等の塩素化炭化水素類などのスチルベン系化合物を溶解させる溶剤が挙げられる。勿論これらの中からバインダーを溶解するものを選択する必要がある。また、バインダーとしては、スチレン、酢酸ビニル、塩化ビニル、アクリル酸エステル、メタクリル酸エステル、ブタジエン等のビニル化合物の重合体及び共重合体、ポリビニルアセタール、ポリカーボネート、ポリエステル、ポリフェニレンオキサイド、ポリウレタン、セルロースエステル、セルロースエーテル、フェノキシ樹脂、けい素樹脂、エポキシ樹脂等スチルべン系化合物と相溶性のある各種ポリマーが挙げられる。バインダーの使用量は通常スチルベン系化合物に対し、０．５〜３０重量倍、好ましくは０．７〜１０重量倍の範囲である。
【００４０】
上記感光層に添加される電荷発生剤粒子、染料色素、電子吸引性化合物としてはいずれも周知のものが使用できる。光を吸収すると極めて高い効率で電荷キャリアーを発生する電荷発生剤粒子としてはセレン、セレン−テルル合金、セレン−ヒ素合金、硫化カドミウム、アモルファスシリコン等の無機電荷発生剤粒子；金属含有フタロシアニン、ペリレン系顔料、チオインジゴ、キナクリドン、ペリレン系顔料、アントラキノン系顔料、アゾ系顔料、ビスアゾ系顔料、トリスアゾ系顔料、テトラキス系アゾ顔料、シアニン系顔料等の有機電荷発生剤粒子が挙げられる。特にビスアゾ系顔料と組み合わせると、感度が向上し、かつ残留電位の小さい優れた感光体が得られる。
【００４１】
染料としては、例えばメチルバイオレット、ブリリアントグリーン、クリスタルバイオレット等のトリフェニルメタン染料、メチレンブルーなどのチアジン染料、キニザリン等のキノン染料及びシアニン染料やビリリウム塩、チアビリリウム塩、ベンゾビリリウム塩等か挙げられる。
また、スチルベン系化合物と電荷移動錯体を形成する電子吸引性化合物としては、例えばクロラニル、２，３−ジクロロ−１，４−ナフトキノン、１−ニトロアントラキノン、１−クロロ−５−ニトロアントラキノン、２−クロロアントラキノン、フェナントレンキノン等のキノン類；４−ニトロベンズアルデヒド等のアルデヒド類；９−ベンゾイルアントラセン、インダンジオン、３，５−ジヒドロベンゾフェノン、２，４，７−トリニトロフルオレノン、２，４，５，７−テトラニトロフルオレノン、３，３′，５，５′−テトラニトロベンゾフェノン等のケトン類；無水フタル酸、４−クロロナフタル酸無水物等の酸無水物；テトラシアノエチレン、テレフタルマロノニトリル、９−アントリルメチリデンマロノニトリル、４−ニトロベンザルマロノニトリル、４−（ｐ−ニトロベンゾイルオキシ）ベンザルマロノニトリル等のシアノ化合物；３−ベンザルフタリド、３−（α−シアノ−ｐ−ニトロベンザル）フタリド、３−（α−シアノ−ｐ−ニトロベンザル）−４，５，６，７−テトラクロロフタリド等のフタリド類等の電子吸引性化合物が挙げられる。
【００４２】
更に、本発明の電子写真用感光体の感光層は成膜性、可撓性、機械的強度を向上させるために周知の可塑剤を含有していてもよい。そのために上記塗布液中に添加する可塑剤としては、フタル酸エステル、リン酸エステル、エポキシ化合物、塩素化パラフィン、塩素化脂肪酸エステル、メチルナフタレンなどの芳香族化合物などが挙げられる。スチルベン系化合物を電荷輸送層中の電荷輸送剤として用いる場合の塗布液は、前記組成のものでよいが、電荷発生剤粒子、染料色素、電子吸引性化合物等は除くか、少量の添加でよい。この場合の電荷発生層としては上記電荷発生剤粒子と必要に応じバインダーポリマーや有機光導電性物質、染料色素、電子吸引性化合物等の溶媒に溶解ないし分散させて得られる塗布液を塗布乾燥した薄層、あるいは前記電荷発生剤を蒸着等の手段により成膜した層が挙げられる。
【００４３】
また、本発明の電子写真用感光体の感光層は、電気特性あるいは繰り返し使用における耐久性を向上させるために周知の添加剤を含有していてもよい。そのために上記塗布液中に添加する添加剤としては、フェノール系化合物、有機リン系化合物、有機イオウ系化合物等が挙げられる。
このようにして形成される感光体はまた、必要に応じ、接着層、中間層、透明絶縁層等を有していてもよいことはいうまでもない。
【００４４】
感光層が形成される導電性基体としては周知の電子写真用感光体に採用されているものがいずれも使用できる。具体的には例えば、アルミニウム、ステンレス、銅等の金属ドラム、シートあるいはこれらの金属箔のラミネート物、蒸着物が挙げられる。更に、金属粉末、カーボンブラック、ヨウ化銅、高分子電解質等の導電性物質を適当なバインダーとともに塗布して導電処理したプラスチックフィルム、プラスチックドラム、紙、紙管等が挙げられる。また、金属粉末、カーボンブラック、炭素繊維等の導電性物質を含有し、導電性となったプラスチックのシートやドラムが挙げられる。
【００４５】
【実施例】
次に本発明を実施例により更に具体的に説明するが、本発明はその要旨を越えない限り、以下の製造例、実施例に限定されるものではない。なお、実施例中「部」とあるのは「重量部」を示す。また、化合物Ｎｏ．は前示例示化合物のＮｏ．に対応する。
製造例１
下式で示されるアルデヒド化合物３．８ｇと
【００４６】
【化１９】

【００４７】
ホスホン酸ジエステル化合物（（Ｃ₂ Ｈ₅ Ｏ）₂ Ｐ（Ｏ）ＣＨ₂ （Ｃ₆ Ｈ₅ ）₂ ）４．５ｇをテトラヒドロフラン７６ｍｌに溶解させ、２０℃でポタシウム−ｔ−ブトキシド１．６ｇを加え、その後室温で２時間３０分攪拌した。その後、反応液に水を加え、常法により抽出し、濃縮、精製処理を行ない、淡黄色ガラス状固体３．８ｇを得た。
この化合物は質量分析測定及び図１に示す赤外吸収スペクトル測定により、前記例示化合物Ｎｏ．１であると同定された。

【００４８】
製造例２
製造例１と同様にして、下式で示されるアルデヒド化合物３．０ｇと、
【００４９】
【化２０】

【００５０】
ホスホン酸ジエステル化合物（（Ｃ₂ Ｈ₅ Ｏ）₂ Ｐ（Ｏ）ＣＨ₂ （Ｃ₆ Ｈ₅ ）₂ ）３．７ｇを反応させて薄オレンジ色固体３．１ｇを得た。
この化合物は質量分析測定及び図２に示す赤外吸収スペクトル測定により、前記例示化合物Ｎｏ．２であると同定された。

【００５１】
実施例１
下記構造式で表されるナフタル酸系ビスアゾ顔料１．０部を、
【００５２】
【化２１】

【００５３】
ジメトキシエタン１４部に加え、サンドグラインダーで分散処理をした後、ジメトキシエタン１４部と４−メトキシ−４−メチルペンタノン−２（三菱化学（株）社製）１４部を加え希釈し、さらに、ポリビニルブチラール（電気化学工業（株）社製、商品名「デンカブチラール」＃６０００−Ｃ）０．５部と、フェノキシ樹脂（ユニオンカーバイド（株）社製、商品名「ＵＣＡＲ」（商標登録）ＰＫＨＨ）０．５部をジメトキシエタンが６部、４−メトキシ−４−メチルペンタノン−２が６部の混合溶媒に溶解した液と混合し、分散液を得た。この分散液を７５μｍの膜厚のポリエステルフィルムに蒸着されたアルミ蒸着層の上に乾燥後の重量が０．２ｇ／ｍ² になる様にワイヤーバーで塗布した後、乾燥して電荷発生層を形成させた。
この上に製造例１で製造したスチルベン系化合物９０部と下記に示すくり返し単位を有するポリカーボネート樹脂
【００５４】
【化２２】

【００５５】
１００部をテトラヒドロフラン９００部に溶解した塗布液を塗布、乾燥し、膜厚２０μｍの電荷輸送層を形成させた。
このようにして得た２層からなる感光層を有する電子写真用感光体に対して感度すなわち半減露光量を測定したところ０．５１ｌｕｘ・ｓｅｃであった。
半減露光量はまず、感光体を暗所で５０μＡコロナ電流により負帯電させ、次いで１ルックスの白色光で露光し、表面電位が−４５０Ｖから−２２５Ｖまで減衰するのに要する露光量を測定することにより求めた。さらに露光時間を９．９秒とした時の表面電位を残留電位として測定したところ、６Ｖであった。
【００５６】
実施例２
実施例１で用いたナフタル酸系ビスアゾ顔料の代りに、Ｘ線回折スペクトルにおいて、ブラッグ角（２θ±０．２°）９．３°、１３．２°、２６．２°、２７．１°に強い回折ピークを示すオキシチタニウムフタロシアニン顔料および製造例１のスチルベン系化合物７０部を用い、電荷輸送層の膜厚を１７μｍとした以外は実施例１と同様にして作成した感光体を７８０ｎｍの光（光量５００ｎＷ）で露光し、半減露光量を測定したところ０．４７μＪ／ｃｍ² であった残留電位は２３Ｖであった。
【００５７】
実施例３
実施例１で使用したスチルベン系化合物の代わりに製造例２で合成したスチルベン系化合物を用いる以外は実施例１と同様にして作成した感光体の半減露光量を測定したところ、０．５１ｌｕｘ・ｓｅｃであった。また残留電位は、７Ｖであった。
【００５８】
実施例４
実施例２で使用したスチルベン系化合物の代わりに製造例２で合成したスチルベン系化合物を用いる以外は実施例２と同様にして作成した感光体の半減露光量を測定したところ、０．４５μＪ／ｃｍ² であった。また残留電位は１３Ｖであった。
【００５９】
比較例
実施例１で使用したスチルベン系化合物の代わりに
【００６０】
【化２３】

【００６１】
で表される化合物を用いる以外は実施例１と同様にして作成した感光体の半減露光量を測定したところ、０．５３ｌｕｘ・ｓｅｃであった。また、残留電位は９Ｖであった。
【００６２】
【発明の効果】
本発明の電子写真用感光体は感度が非常に高く、かつ、かぶりの原因となる残留電位が小さく、とくに光疲労が少ないために繰り返し使用や強露光による残留電位の蓄積や、表面電位および感度の変動が小さく耐久性に優れており、ＰＰＣ用に適しているだけでなく、性能の安定性、信頼性が特に要求されるレーザープリンタ、液晶シヤッタープリンタ、ＬＥＤプリンタ等のプリンタ用感光体にも適した感光体である。
【図面の簡単な説明】
【図１】例示化合物Ｎｏ．１の赤外吸収スペクトル図。
【図２】例示化合物Ｎｏ．２の赤外吸収スペクトル図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photoreceptor. More particularly, the present invention relates to a highly sensitive and high performance electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive substance.
[0002]
[Prior art]
Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors. However, selenium and cadmium sulfide must be recovered as poisonous substances, selenium is inferior in heat resistance because it is crystallized by heat, cadmium sulfide and zinc oxide are inferior in moisture resistance, and zinc oxide is not in printing durability. Therefore, efforts to develop new photoreceptors are continuing. Recently, research on using organic photoconductive substances for the photosensitive layer of electrophotographic photoreceptors has progressed, and some of them have been put to practical use. Organic photoconductive substances are lighter in weight, easier to form films, and easier to produce photoreceptors than inorganic ones. Depending on the type, there are advantages such that a transparent photoconductor can be produced and the material is harmless.
[0003]
Recently, so-called function-separated type photoconductors, which share the functions of charge carrier generation and transport with different compounds, are effective in achieving high sensitivity. Photoconductors have also been put into practical use.
As the charge carrier transport medium, there are a case where a high molecular photoconductive compound such as polyvinyl carbazole is used and a case where a low molecular photoconductive compound is dispersed and dissolved in a binder polymer.
[0004]
[Problems to be solved by the invention]
In particular, an organic low molecular weight photoconductive compound can select a polymer having excellent film properties, flexibility, adhesiveness, etc. as a binder, so that a photoconductor excellent in mechanical properties can be easily obtained. Various proposals have been made so far because it has the advantage of being able to. (For example, see Japanese Patent Publication No. 60-34099, Japanese Unexamined Patent Publication No. 59-114545, Japanese Unexamined Patent Publication No. 60-39654, etc.)
However, conventionally known compounds are not always satisfactory for producing a highly sensitive photoreceptor.
In view of such circumstances, an object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and a small increase in residual potential.
[0005]
[Means for Solving the Problems]
The present inventors diligently studied an organic low-molecular photoconductive compound that can satisfy these objects, and found that a specific stilbene-based compound is suitable, leading to the present invention. That is, the gist of the present invention is an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, wherein the photosensitive layer contains a stilbene compound represented by the following general formula (I). It exists in the electrophotographic photoreceptor characterized.
[0006]
[Formula 4]

[0007]
{Wherein Ar¹ And Ar² At least one of the following general formula (II)Or ( III )soRepresents the group shownThe
[0008]
[Chemical formula 5]

[0009]
Ar¹ And Ar² Is the general formula (II)and( III Other thanIn this case, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a complex which may have a substituent. Represents a condensed polycyclic group which may have a cyclic group or a substituent.(However, as the condensed polycyclic group which may have a substituent, the general formula (IV) Is excluded. This general formula (IV) In the formula, C and D represent a naphthalene ring which may be bonded to have a substituent. C and D are further divalent residues Z that form a ring structure. ^Three It has a condensed ring containing. ). Ar^Three Has an arylene group which may have a substituent, a divalent heterocyclic group which may have a substituent, a divalent condensed polycyclic group or a substituent which may have a substituent. Represents an optionally biphenylene group. R¹ , R² , R^Three And R^Four Each independently has a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. It represents a heterocyclic group which may optionally be substituted or a condensed polycyclic group which may have a substituent. R^Five Represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or a condensed polycyclic group which may have a substituent. n represents 0 or an integer of 1 to 5, and when n is 2 or more, each R^Three And R^Four May be the same or different.
[0010]
Formula (II)and( III )ofIn the formula, A and B each represent a benzene ring which may have a substituent.Wow. A and B areFurther, each of the divalent residues Z forming a ring structure¹ Or Z ² TheIt has a condensed ring. R⁶ , R⁷ , R⁸ , R⁹ , R^TenAnd R¹¹Each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aryl group which may have a substituent. Or it represents the heterocyclic group which may have a substituent. Ar¹ And Ar² Is the general formula (II)and( III Other thanIn the case of Ar¹ And Ar^Three And Ar² And Ar^Three May be linked directly or through a linking group, and R² And R^Five (When n = 0) and R^Four And R^Five(When n = 1 to 5) may be linked directly or via a bonding group. }
[0011]
The present invention will be described in detail below.
The electrophotographic photoreceptor of the present invention contains a stilbene compound represented by the general formula (I) in the photosensitive layer. In the general formula (I), Ar¹And Ar²At least one of represents a group represented by the general formula (II), (III) or (IV). In the general formulas (II) to (IV), A and B each represent a benzene ring that may have a substituent, and C and D each represent a naphthalene ring that may have a substituent by bonding. These substituents include hydrogen atom; hydroxyl group; halogen atom such as chlorine atom, bromine atom and iodine atom; alkyl having about 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group, butyl group and hexyl group. Group: alkoxy group such as methoxy group, ethoxy group, butoxy group; allyl group; aralkyl group such as benzyl group, naphthylmethyl group, phenethyl group; aryloxy group such as phenoxy group, triloxy group; benzyloxy group, phenethyloxy group Aralkyloxy groups such as phenyl groups, aryl groups such as naphthyl groups, heterocyclic groups such as thienyl groups, furyl groups, etc .; Arites such as styryl groups, naphthyl vinyl groups, etc. Divinylamino groups such as dimethylamino group and diethylamino group; Diarylamino groups such as diphenylamino group and dinaphthylamino group; Diaralkylamino groups such as dibenzylamino group and diphenethylamino group; Dithienylamino group; Examples include diheterocyclic amino groups such as difurylamino groups; diallylamino groups; disubstituted amino groups in combination with the above amino groups; nitro groups; acyl groups such as acetyl groups and benzoyl groups.
A, B, C and D are each a divalent residue Z that forms a ring structure.¹, Z²Or Z^ThreeIt has a condensed ring containing. Examples of groups represented by formulas (II), (III), and (IV) include the following general formulas (VI) to (XV).
[0012]
[Chemical 6]

[0013]
In the above general formulas (VI) to (XV), X and Y represent a benzene ring which may have one or more substituents, and examples of the substituent include those exemplified as the substituents A to D. .
Ar¹And Ar²In the cases other than the general formulas (II), (III) and (IV), alkyl groups having about 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group, butyl group and hexyl group; benzyl group and naphthylmethyl Group, aryl groups such as phenethyl group, aryl groups such as phenyl group and naphthyl group; heterocyclic groups such as thienyl group, furyl group and pyridyl group; and condensed polycyclic groups such as pyrenyl group, anthracenyl group and fluorenyl group. These alkyl group, aralkyl group, aryl group, heterocyclic group and condensed polycyclic group may have a substituent, such as a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom or an iodine atom. Alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group; alkoxy groups such as methoxy group, ethoxy group and butoxy group; allyl group; aralkyl groups such as benzyl group, naphthylmethyl group and phenethyl group; Aryloxy groups such as phenoxy group and triloxy group; aralkyloxy groups such as benzyloxy group and phenethyloxy group; aryl groups such as phenyl group and naphthyl group; heterocyclic groups such as thienyl group and furyl group; styryl group and naphthylvinyl Aryl vinyl groups such as groups; dialkylamino groups such as dimethylamino and diethylamino groups; diphenylamino A diarylamino group such as a diarylamino group such as a dinaphthylamino group, a diaralkylamino group such as a diphenethylamino group; a diheterocyclic amino group such as a dithienylamino group or a difurylamino group; a diallylamino group; A di-substituted amino group, a nitro group, an acyl group such as an acetyl group or a benzoyl group, and the like.
[0014]
Preferably Ar¹And Ar²At least one of the groups is a group represented by the general formula (II) or (IV).
Ar^ThreeRepresents an arylene group such as a phenylene group or a naphthylene group; a divalent heterocyclic group such as a thienylene group, a furylene group or a pyridylene group; a divalent condensed polycyclic group such as a pyrenylene group, an anthracenylene group or a fluorenylene group; In particular, an arylene group, a divalent condensed polycyclic group and a biphenylene group are preferable. These arylene groups, divalent heterocyclic groups, divalent condensed polycyclic groups, and biphenylene groups may have a substituent, such as a hydroxyl group; a chlorine atom, a bromine atom, an iodine atom, etc. Halogen atoms of: alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group; alkoxy groups such as methoxy group, ethoxy group, butoxy group; allyl group; benzyl group, naphthylmethyl group, phenethyl group, etc. Aralkyl groups; aryloxy groups such as phenoxy groups and triloxy groups; aralkyloxy groups such as benzyloxy groups and phenethyloxy groups; aryl groups such as phenyl groups and naphthyl groups; heterocyclic groups such as thienyl groups and furyl groups; styryl groups Aryl vinyl groups such as naphthyl vinyl group; dialkylamino groups such as dimethylamino group and diethylamino group; diphenylamino group Diarylamino groups such as dinaphthylamino groups, diaralkylamino groups such as dibenzylamino groups and diphenethylamino groups; diheterocyclic amino groups such as dithienylamino groups and difurylamino groups; diallylamino groups; Examples thereof include a combined di-substituted amino group; a nitro group; an acyl group such as an acetyl group and a benzoyl group.
[0015]
R¹, R², R^ThreeAnd R^FourAre each a hydrogen atom; an alkyl group having about 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, or a hexyl group; an aryl group such as a phenyl group or a naphthyl group; a benzyl group, a naphthylmethyl group, It represents an aralkyl group such as a phenethyl group; a heterocyclic group such as a thienyl group, a furyl group, or a pyridyl group; and a condensed polycyclic group such as a pyrenyl group, an anthracenyl group, or a fluorenyl group, which may be the same as or different from each other. These alkyl groups, aryl groups, aralkyl groups, heterocyclic groups, and condensed polycyclic groups may have a substituent, such as a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom, or an iodine atom. Alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group; alkoxy groups such as methoxy group, ethoxy group and butoxy group; allyl group; aralkyl groups such as benzyl group, naphthylmethyl group and phenethyl group; Aryloxy groups such as phenoxy group and triloxy group; aralkyloxy groups such as benzyloxy group and phenethyloxy group; aryl groups such as phenyl group and naphthyl group; heterocyclic groups such as thienyl group and furyl group; styryl group and naphthylvinyl Aryl vinyl groups such as groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diphenylamino groups; Diarylamino groups such as phthalylamino groups, diaralkylamino groups such as dibenzylamino groups and diphenethylamino groups; diheterocyclic amino groups such as dithienylamino groups and difurylamino groups; diallylamino groups; and combinations of the above amino groups Disubstituted amino groups; nitro groups; acyl groups such as acetyl groups and benzoyl groups.
[0016]
R^FiveRepresents an aryl group such as a phenyl group and a naphthyl group; a heterocyclic group such as a thienyl group, a furyl group and a pyridyl group; and a condensed polycyclic group such as a pyrenyl group, an anthracenyl group and a fluorenyl group. These aryl group, heterocyclic group and condensed polycyclic group may have a substituent, and examples of the substituent include a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom and an iodine atom; a methyl group, an ethyl group, Alkyl groups such as propyl group, butyl group and hexyl group; alkoxy groups such as methoxy group, ethoxy group and butoxy group; allyl group; aralkyl groups such as benzyl group, naphthylmethyl group and phenethyl group; phenoxy group and triloxy group Aryloxy groups; aralkyloxy groups such as benzyloxy groups and phenethyloxy groups; aryl groups such as phenyl groups and naphthyl groups; heterocyclic groups such as thienyl groups and furyl groups; arylvinyl groups such as styryl groups and naphthylvinyl groups; Dialkylamino group such as dimethylamino group and diethylamino group; dialkylamino group such as diphenylamino group and dinaphthylamino group Diaralkylamino groups such as diamino groups, dibenzylamino groups, diphenethylamino groups; diheterocyclic amino groups such as dithienylamino groups, difurylamino groups; diallylamino groups; disubstituted amino groups in combination of the above amino groups; Nitro group; acyl group such as acetyl group and benzoyl group.
[0017]
n represents 0 or an integer of 1 to 5, and when n is 2 or more, each R^ThreeMay be the same or different from each other, and each R^FourMay be the same as or different from each other.
In the general formulas (II), (III) and (IV), R⁶, R⁷, R⁸, R⁹, R^TenAnd R¹¹Each represents a hydrogen atom; a halogen atom such as a chlorine atom, a bromine atom or an iodine atom; a hydroxyl group; an alkyl group having about 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group or a hexyl group; a benzyl group or a naphthyl group An aralkyl group such as a methyl group or a phenethyl group; an aryl group such as a phenyl group or a naphthyl group; a heterocyclic group such as a thienyl group, a furyl group, or a pyridyl group, which may be the same or different. These alkyl groups, aralkyl groups, aryl groups, and heterocyclic groups may have a substituent, such as a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom, or an iodine atom; a methyl group, an ethyl group Alkyl groups such as propyl group, butyl group and hexyl group; alkoxy groups such as methoxy group, ethoxy group and butoxy group; allyl group; aralkyl groups such as benzyl group, naphthylmethyl group and phenethyl group; phenoxy group and triloxy group Aryloxy groups such as benzyloxy group and phenethyloxy group; aryl groups such as phenyl group and naphthyl group; heterocyclic groups such as thienyl group and furyl group; arylvinyl groups such as styryl group and naphthylvinyl group Dialkylamino groups such as dimethylamino and diethylamino groups; diphenylamino groups and dinaphthylamino A diarylamino group such as a dibenzylamino group and a diphenethylamino group; a diheterocyclic amino group such as a dithienylamino group and a difurylamino group; a diallylamino group; a di-substitution combining the above amino groups Amino group; nitro group; acyl group such as acetyl group and benzoyl group.
[0018]
Ar¹And Ar²Is other than the general formulas (II), (III) and (IV), Ar¹And Ar^ThreeOr Ar²And Ar^ThreeMay be linked directly or via a linking group. For example, the following general formulas (XVI), (XVII), (VXIII), (XIX) and (XX) can be adopted.
[0019]
[Chemical 7]

[0020]
In the general formula (I), R²And R^Five(When n = 0) and R^FourAnd R^Five(When n = 1 or more) may be linked directly or via a linking group. For example, the following general formulas (XXI), (XXII), (XXIII), (XXIV), (XXV), (XXVI) ), (XXVII), (XXVIII) and (XXIX).
[0021]
[Chemical 8]

[0022]
In the above general formulas (XVI) to (XXIX), X and Y represent a benzene ring which may have one or more substituents, the substituents being hydrogen atom; hydroxyl group; chlorine atom, bromine atom, iodine atom, etc. Halogen atoms of: alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group; alkoxy groups such as methoxy group, ethoxy group, butoxy group; allyl group; benzyl group, naphthylmethyl group, phenethyl group, etc. Aralkyl groups; aryloxy groups such as phenoxy groups and triloxy groups; aralkyloxy groups such as benzyloxy groups and phenethyloxy groups; aryl groups such as phenyl groups and naphthyl groups; heterocyclic groups such as thienyl groups and furyl groups; styryl groups Aryl vinyl groups such as naphthyl vinyl group; dialkylamino groups such as dimethylamino group and diethylamino group; Diarylamino groups such as dibenzylamino group and diphenethylamino group; diheterocyclic amino groups such as dithienylamino group and difurylamino group; diallylamino group; Examples thereof include di-substituted amino groups combined with amino groups; nitro groups; acyl groups such as acetyl groups and benzoyl groups.
[0023]
Among the stilbene compounds represented by the general formula (I), particularly preferable compounds are Ar¹And Ar²At least one of the groups of general formula (II) or general formula (IV), Ar^ThreeIs an arylene group, a condensed polycyclic group or a biphenyl group, and n is a compound of 0 or 1. In particular, the group of general formula (II) is preferably a group of formula (VI), and the group of general formula (IV) is preferably a group of formula (XIV).
The stilbene compound represented by the general formula (I) can be produced, for example, using a Wittig-Hornor-Emmons reaction between diethyl phosphonate and a carbonyl compound as shown below.
[0024]
[Chemical 9]

[0025]
(Wherein Ar¹, Ar², Ar^Three, R¹, R², R^Three, R^FourAnd R^FiveHas the same meaning as in general formula (I). R¹²Represents an alkyl group. )
That is, potassium alkoxide, carbonyl compound of general formula (XXX) or general formula (XXXI) and phosphonic acid diester of general formula (XXXII) in a solvent such as tetrahydrofuran, 1,2-dimethoxyethane, N, N-dimethylformamide, By reacting in the presence of a base such as sodium alkoxide or sodium hydride, a compound of the general formula (I) is obtained. After the reaction, if necessary, purification by a known means such as recrystallization or column chromatography will give a high-purity target product.
[0026]
In addition, the compound of general formula (I) has a regioisomer based on a carbon-carbon double bond. The compound obtained by the above method is a mixture of a cis isomer and a trans isomer. In the present specification, the compound of the general formula (I) means a mixture of a cis isomer and a trans isomer unless otherwise specified.
Specific examples of the stilbene compound represented by the general formula (I) are illustrated below, but the present invention is not limited to the following compounds.
[0027]
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[0028]
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[0029]
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[0030]
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[0031]
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[0032]
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[0033]
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[0034]
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[0035]
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[0036]
The stilbene compound represented by the general formula (I) shows extremely excellent performance as an organic photoconductor. In particular, when used as a charge transfer agent, it provides a photoconductor with high sensitivity and excellent durability.
Various forms of the photosensitive layer of the electrophotographic photoreceptor are known, and any of the photosensitive layers of the electrophotographic photoreceptor of the present invention may be used. For example, a photosensitive layer in which a stilbene compound and, if necessary, a dye or electron-withdrawing compound as a sensitizer are added in a binder, charge generator particles and a stilbene compound that generate charge carriers with high efficiency when absorbing light. A photosensitive layer added in a binder, a charge transport layer composed of a stilbene compound and a binder, and charge generator particles that generate charge carriers with extremely high efficiency to absorb light, or a charge generation layer composed of this and a binder are laminated. Examples thereof include a photosensitive layer.
[0037]
In these photosensitive layers, in addition to the stilbene compound represented by the general formula (I), other known arylamine compounds, hydrazone compounds, stilbene compounds having excellent performance as organic photoconductors are mixed. May be.
In the present invention, when the stilbene compound represented by the above general formula (I) is used in a charge transport layer of a photosensitive layer composed of two layers of a charge generation layer and a charge transport layer, the sensitivity is particularly high and the residual potential is small. In addition, when it is repeatedly used, it is possible to obtain a photoreceptor having excellent durability with little fluctuation in surface potential, lowering of sensitivity, accumulation of residual potential, and the like.
[0038]
The electrophotographic photoreceptor of the present invention dissolves a stilbene compound represented by the above general formula (I) in a suitable solvent together with a binder according to a conventional method, and absorbs light as required to generate charge carriers with extremely high efficiency. A coating solution obtained by adding generated charge generating particles, sensitizing dyes, electron-withdrawing compounds, or plasticizers, pigments and other additives is coated on a conductive support and dried, usually several microns. It can be produced by forming a photosensitive layer having a film thickness of ˜tens of microns, preferably 10 microns to 40 microns. In the case of a photosensitive layer comprising two layers of a charge generation layer and a charge transport layer, the charge generation layer is formed on the charge transport layer obtained by coating the coating layer on the charge generation layer or coating the coating solution. Can be produced.
[0039]
Solvents for preparing the coating solution include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide, acetonitrile, N -Aprotic polar solvents such as methyl pyrrolidone and dimethyl sulfoxide; esters such as ethyl acetate, methyl formate and methyl cellosolve acetate; and solvents that dissolve stilbene compounds such as chlorinated hydrocarbons such as dichloroethane and chloroform. . Of course, it is necessary to select one that dissolves the binder. As binders, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, butadiene, polyvinyl acetal, polycarbonate, polyester, polyphenylene oxide, polyurethane, cellulose ester, Examples include various polymers compatible with stilbene compounds such as cellulose ether, phenoxy resin, silicon resin, and epoxy resin. The usage-amount of a binder is 0.5-30 weight times normally with respect to a stilbene type compound, Preferably it is the range of 0.7-10 weight times.
[0040]
As the charge generating particles, the dye coloring matter, and the electron withdrawing compound added to the photosensitive layer, known ones can be used. Charge generator particles that generate charge carriers with extremely high efficiency upon absorption of light include inorganic charge generator particles such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, and amorphous silicon; metal-containing phthalocyanine, perylene-based particles Examples thereof include organic charge generator particles such as pigments, thioindigo, quinacridone, perylene pigments, anthraquinone pigments, azo pigments, bisazo pigments, trisazo pigments, tetrakis azo pigments, and cyanine pigments. In particular, when combined with a bisazo pigment, an excellent photoreceptor with improved sensitivity and low residual potential can be obtained.
[0041]
Examples of the dye include triphenylmethane dyes such as methyl violet, brilliant green and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, bililium salts, thiabililium salts, and benzobililium salts.
Examples of the electron-withdrawing compound that forms a charge transfer complex with a stilbene compound include chloranil, 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2- Quinones such as chloroanthraquinone and phenanthrenequinone; aldehydes such as 4-nitrobenzaldehyde; 9-benzoylanthracene, indandione, 3,5-dihydrobenzophenone, 2,4,7-trinitrofluorenone, 2,4,5 Ketones such as 7-tetranitrofluorenone and 3,3 ′, 5,5′-tetranitrobenzophenone; acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride; tetracyanoethylene, terephthalmalononitrile, 9- Anthrylmethylidenemalononitrile, 4-nitro Cyano compounds such as nzalmalononitrile, 4- (p-nitrobenzoyloxy) benzalmalononitrile; 3-benzalphthalide, 3- (α-cyano-p-nitrobenzal) phthalide, 3- (α-cyano-p-nitrobenzal) ) Electron attractive compounds such as phthalides such as -4,5,6,7-tetrachlorophthalide.
[0042]
Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known plasticizer in order to improve the film formability, flexibility, and mechanical strength. For this purpose, examples of the plasticizer added to the coating solution include aromatic compounds such as phthalic acid esters, phosphoric acid esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and methylnaphthalene. The coating liquid in the case of using a stilbene compound as a charge transport agent in the charge transport layer may be of the above composition, but the charge generator particles, dye pigments, electron withdrawing compounds, etc. may be excluded or a small amount may be added. . In this case, as the charge generation layer, a coating solution obtained by dissolving or dispersing in the solvent such as a binder polymer, an organic photoconductive substance, a dye pigment, or an electron-withdrawing compound was coated and dried. Examples include a thin layer or a layer formed by depositing the charge generating agent by means such as vapor deposition.
[0043]
The photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known additive in order to improve electrical characteristics or durability in repeated use. For this purpose, examples of the additive added to the coating solution include phenolic compounds, organic phosphorus compounds, and organic sulfur compounds.
It goes without saying that the photoreceptor formed in this manner may also have an adhesive layer, an intermediate layer, a transparent insulating layer, and the like, if necessary.
[0044]
As the conductive substrate on which the photosensitive layer is formed, any of those used in known electrophotographic photoreceptors can be used. Specific examples include metal drums such as aluminum, stainless steel, and copper, sheets, laminates of these metal foils, and deposits. Furthermore, a plastic film, a plastic drum, paper, a paper tube, and the like obtained by applying a conductive material such as metal powder, carbon black, copper iodide, and a polymer electrolyte together with an appropriate binder to conduct a conductive treatment may be used. Further, a plastic sheet or drum containing a conductive material such as metal powder, carbon black, or carbon fiber and becoming conductive can be used.
[0045]
【Example】
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following production examples and examples as long as the gist thereof is not exceeded. In the examples, “parts” means “parts by weight”. In addition, Compound No. No. of the exemplified compound shown above. Corresponding to
Production Example 1
3.8 g of an aldehyde compound represented by the following formula:
[0046]
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[0047]
Phosphonic acid diester compounds ((C₂H_FiveO)₂P (O) CH₂(C₆H_Five)₂) 4.5 g was dissolved in 76 ml of tetrahydrofuran, 1.6 g of potassium t-butoxide was added at 20 ° C., and the mixture was stirred at room temperature for 2 hours and 30 minutes. Thereafter, water was added to the reaction solution, followed by extraction by a conventional method, concentration and purification treatment, to obtain 3.8 g of a pale yellow glassy solid.
This compound was subjected to mass spectrometric measurement and infrared absorption spectrum measurement shown in FIG. 1 was identified.

[0048]
Production Example 2
In the same manner as in Production Example 1, 3.0 g of an aldehyde compound represented by the following formula:
[0049]
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[0050]
Phosphonic acid diester compound ((C₂H_FiveO)₂P (O) CH₂(C₆H_Five)₂) 3.7 g to give 3.1 g of a light orange solid.
This compound was subjected to mass spectrometric measurement and infrared absorption spectrum measurement shown in FIG. 2 was identified.

[0051]
Example 1
1.0 part of a naphthalic acid-based bisazo pigment represented by the following structural formula,
[0052]
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[0053]
In addition to 14 parts of dimethoxyethane, after a dispersion treatment with a sand grinder, 14 parts of dimethoxyethane and 14 parts of 4-methoxy-4-methylpentanone-2 (manufactured by Mitsubishi Chemical Corporation) were added and diluted. 0.5 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Butyral” # 6000-C) and phenoxy resin (manufactured by Union Carbide Co., Ltd., trade name “UCAR” (registered trademark) PKHH) ) 0.5 part was mixed with a solution in which 6 parts of dimethoxyethane and 6 parts of 4-methoxy-4-methylpentanone-2 were dissolved to obtain a dispersion. The weight of this dispersion after drying on an aluminum vapor-deposited layer deposited on a polyester film having a thickness of 75 μm is 0.2 g / m.²After being applied with a wire bar, a charge generation layer was formed by drying.
A polycarbonate resin having 90 parts of the stilbene compound produced in Production Example 1 and a repeating unit shown below.
[0054]
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[0055]
A coating solution prepared by dissolving 100 parts in 900 parts of tetrahydrofuran was applied and dried to form a charge transport layer having a thickness of 20 μm.
The sensitivity, that is, the half-exposure amount of the electrophotographic photoreceptor having the two-layered photosensitive layer thus obtained was measured and found to be 0.51 lux · sec.
The half-exposure amount is determined by measuring the exposure amount required for the surface potential to attenuate from -450 V to -225 V by first negatively charging the photoconductor with a 50 μA corona current in the dark and then exposing with 1 lux of white light. Determined by Furthermore, when the surface potential when the exposure time was 9.9 seconds was measured as a residual potential, it was 6 V.
[0056]
Example 2
Instead of the naphthalic acid-based bisazo pigment used in Example 1, in the X-ray diffraction spectrum, Bragg angles (2θ ± 0.2 °) of 9.3 °, 13.2 °, 26.2 °, 27.1 ° A photoconductor produced in the same manner as in Example 1 except that the oxytitanium phthalocyanine pigment showing a strong diffraction peak and 70 parts of the stilbene compound of Production Example 1 were used and the film thickness of the charge transport layer was 17 μm was used. When exposed at (light quantity 500 nW) and half-exposure was measured, 0.47 μJ / cm²The residual potential was 23V.
[0057]
Example 3
The half-exposure amount of the photoconductor prepared in the same manner as in Example 1 except that the stilbene compound synthesized in Production Example 2 was used instead of the stilbene compound used in Example 1 was 0.51 lux · sec. Met. The residual potential was 7V.
[0058]
Example 4
The half-exposure amount of the photoconductor prepared in the same manner as in Example 2 except that the stilbene compound synthesized in Production Example 2 was used instead of the stilbene compound used in Example 2 was 0.45 μJ / cm.²Met. The residual potential was 13V.
[0059]
Comparative example
Instead of the stilbene compound used in Example 1
[0060]
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[0061]
When the half-exposure amount of a photoconductor prepared in the same manner as in Example 1 except that the compound represented by the formula (1) was used was measured, it was 0.53 lux · sec. The residual potential was 9V.
[0062]
【The invention's effect】
The electrophotographic photoreceptor of the present invention has very high sensitivity and a small residual potential that causes fogging. Particularly, since there is little light fatigue, accumulation of residual potential due to repeated use or strong exposure, surface potential and sensitivity. It is not only suitable for PPC, but also for photoconductors for printers such as laser printers, liquid crystal shutter printers, and LED printers that require particularly stable performance and reliability. It is a suitable photoconductor.
[Brief description of the drawings]
1 is an exemplary compound No. 1; FIG.
FIG. 2 is an infrared absorption spectrum diagram of FIG.

Claims (7)

An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, wherein the photosensitive layer contains a stilbene compound represented by the following general formula (I): .

{In the formula, at least one of Ar ¹ and Ar ² represents a group represented by the following general formula (II) or ( III ) .

When Ar ¹ and Ar ² are other than the general formulas (II) and ( III ) , they may have an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. An optionally substituted aryl group, an optionally substituted heterocyclic group or an optionally substituted condensed polycyclic group (however, an optionally substituted condensed polycyclic group) as the general formula (IV) is excluded. wherein, C, D .C and D represent the bound naphthalene ring that may have a substituent group of the general formula (IV), further, the ring structure Divalent residue Z ³ forming It has a condensed ring containing. ) Ar ³ is an arylene group which may have a substituent, a divalent heterocyclic group which may have a substituent, a divalent condensed polycyclic group or a substituent which may have a substituent. The biphenylene group which may have is represented. R ¹ , R ² , R ³ and R ⁴ each independently have a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. An aryl group that may be substituted, a heterocyclic group that may have a substituent, or a condensed polycyclic group that may have a substituent. R ⁵ represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or a condensed polycyclic group which may have a substituent. However, among the substituents that R ⁴ and R ⁵ may have, an alkoxy group and a hydroxyl group are excluded. n represents 0 or an integer of 1 to 5, and when n is 2 or more, R ³ and R ⁴ may be the same or different. Compounds of general formula (II) and (III), A and B, Wath table a benzene ring which may have a substituent, respectively. A and B each further have a condensed ring containing a divalent residue Z ¹ or Z ² that forms a ring structure. R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ each independently have a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, or a substituent. An aralkyl group which may be substituted, an aryl group which may have a substituent or a heterocyclic group which may have a substituent. When Ar ¹ and Ar ² are other than the general formulas (II) and ( III ) , Ar ¹ and Ar ³ and Ar ² and Ar ³ may be linked directly or via a bonding group, and R ² and R ⁵ (when n = 0) and R ⁴ and R ⁵ (when n = 1 to 5) may be linked directly or via a linking group. } 2. The electrophotographic process according to claim 1, wherein the photosensitive layer contains a charge generating agent and a charge transporting agent, and the stilbene compound represented by the general formula (I) according to claim 1 is used as the charge transporting agent. Photoconductor. The photosensitive layer has at least a charge transport layer containing a charge transport agent and a charge generation layer containing a charge generator and a binder resin, and the charge transport agent is represented by the general formula (I) according to claim 1. 3. The electrophotographic photoreceptor according to claim 1, wherein a stilbene compound is used. The photosensitive layer has a charge generation layer containing at least a charge generation agent, and a charge transport layer containing a charge transfer agent and a binder resin, and the charge transfer agent is represented by the general formula (I) according to claim 1. 4. The electrophotographic photoreceptor according to claim 2, wherein a stilbene compound is used. 5. The electrophotographic photoreceptor according to claim 2, wherein the charge generating agent is an azo pigment having a coupler component represented by the following general formula (V) in the molecule.

(In the formula, B represents a divalent group forming a nitrogen-containing heterocyclic ring or a divalent aromatic hydrocarbon ring group condensed with a nitrogen-containing heterocyclic ring, and these have a substituent. May be.) The charge generator is oxytitanium phthalocyanine showing a main diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in the X-ray diffraction spectrum, or (2θ ± 0.2 °) of 9.3 °, 13 5. The electrophotographic photoreceptor according to claim 2, which is oxytitanium phthalocyanine having main diffraction peaks at 2 °, 26.2 °, and 27.1 °. In the stilbene compound, at least ^one of Ar ¹ and Ar ² in the general formula (I) is a group selected from the group represented by the general formula (II) or the general formula (IV), and Ar ³ is an arylene group or a condensed group 7. The electrophotographic photoreceptor according to claim 1, wherein the photoreceptor is a group selected from a polycyclic group and a biphenylene group, and n is a compound selected from 0 or 1.

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