JP3576953B2 - Electrophotographic photoreceptor, benzofuran-styryl compound used therein, and method for producing the same - Google Patents

Description

【００１２】
（式中、Ａｒ_１は置換基を含んでもよいアリレン基または置換基を含んでもよい２価の複素環基を示す。Ａｒ_２は、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基または置換基を含んでもよいアラルキル基を示す。Ａｒ_３およびＡｒ_４は、各々、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基、置換基を含んでもよいアラルキル基、置換基を含んでもよい炭素数１〜３のアルキル基または水素原子を示す。ａは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示し、ｎは１〜４の整数を示す。ただしｎが２以上のとき、複数のａは同一でも異なってもよく、互いに環を形成してもよい。）
【００１３】
本発明に従えば、電荷移動物質として一般式（Ｉ）で示されるベンゾフラン−スチリル化合物を含有することによって、高感度かつ高耐久性を有する電子写真感光体を提供することができる。すなわち該ベンゾフラン−スチリル化合物は広い共役系を有しているため、電荷移動度を高くして電子写真感光体の残留電位特性を向上させることができる。また該ベンゾフラン−スチリル化合物は、バインダポリマとの相溶性に優れいるため、感光層中に多量に含有させて電子写真感光体の光感度を向上させることができる。さらに該ベンゾフラン−スチリル化合物は結晶として析出しにくいので、電子写真感光体の繰返し使用時の特性を安定させることができる。
【００１４】
また本発明は、前記ベンゾフラン−スチリル化合物が、下記一般式（ＩＩ）で示される化合物であることを特徴とする。
【００１５】
【化１０】

【００１６】
（式中、ｂは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示し、ｍは１〜４の整数を示す。ただしｍが２以上のとき、複数のｂは同一でも異なってもよい。Ａｒ_２、Ａｒ_３、Ａｒ_４、ａおよびｎは、一般式（Ｉ）において示したものと同義である。）
【００１７】
本発明に従えば、電荷移動物質として一般式（Ｉ）と同様の特性を有する一般式（ＩＩ）で示されるベンゾフラン−スチリル化合物を含有することによって、高感度かつ高耐久性を有する電子写真感光体を提供することができる。
【００１８】
また本発明は、前記ベンゾフラン−スチリル化合物が、下記一般式（ＩＩＩ）で示される化合物であることを特徴とする。
【００１９】
【化１１】

【００２０】
（式中、ｄは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示し、ｌは１〜５の整数を示す。ただしｌが２以上のとき、複数のｄは同一でも異なってもよい。Ａｒ_３、Ａｒ_４、ａ、ｂ、ｎおよびｍは、一般式（ＩＩ）において示したものと同義である。）
【００２１】
本発明に従えば、電荷移動物質として一般式（Ｉ）と同様の特性を有する一般式（ＩＩＩ）で示されるベンゾフラン−スチリル化合物を含有することによって、高感度かつ高耐久性を有する電子写真感光体を提供することができる。
【００２２】
また本発明は、前記ベンゾフラン−スチリル化合物が、下記一般式（ＩＶ）で示される化合物であることを特徴とする。
【００２３】
【化１２】

【００２４】
（式中、ｅは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子と示し、ｋは１〜５の整数を示す。ただしｋが２以上のとき、複数のｅは同一でも異なってもよい。Ａｒ_３、Ａｒ_４、ａ、ｂ、ｎおよびｍは、一般式（ＩＩＩ）において示したものと同義である。）
【００２５】
本発明に従えば、電荷移動物質として一般式（Ｉ）と同様の特性を有する一般式（ＩＶ）で示されるベンゾフラン−スチリル化合物を含有することによって、高感度かつ高耐久性を有する電子写真感光体を提供することができる。
【００２６】
また本発明は、前記感光層が、電荷発生物質を含有する電荷発生層と、前記電荷移動物質を含有する電荷移動層との積層構造から成ることを特徴とする。
【００２７】
本発明に従えば、積層構造の感光層の電荷移動層に、前記ベンゾフラン−スチリル化合物を電荷移動物質として含有することによって、高感度かつ高耐久性を有する積層型の電子写真感光体を提供することができる。
【００２８】
また本発明は、前記感光層が、電荷発生物質と前記電荷移動物質とを含有する単一層から成ることを特徴とする。
【００２９】
本発明に従えば、単一層の感光層に、前記ベンゾフラン−スチリル化合物を電荷移動物質として含有することによって、正帯電においても優れた感度および繰返し特性を有する単層型の電子写真感光体を提供することができる。
【００３０】
本発明は、下記一般式（Ｉ）で示されるベンゾフラン−スチリル化合物である。
【００３１】
【化１３】

【００３２】
（式中、Ａｒ_１は置換基を含んでもよいアリレン基または置換基を含んでもよい２価の複素環基を示す。Ａｒ_２は、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基または置換基を含んでもよいアラルキル基を示す。Ａｒ_３およびＡｒ_４は、各々、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基、置換基を含んでもよいアラルキル基、置換基を含んでもよい炭素数１〜３のアルキル基または水素原子を示す。ａは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示し、ｎは１〜４の整数を示す。ただしｎが２以上のとき、複数のａは同一でも異なってもよく、互いに環を形成してもよい。）
【００３３】
本発明に従えば、一般式（Ｉ）で示されるベンゾフラン−スチリル化合物は、広い共役系を有し、バインダポリマとの相溶性に優れ、結晶として析出しにくいという特徴を有することによって、高感度かつ高耐久性を有する電子写真感光体用の電荷移動物質として用いることができる化合物を提供することができる。すなわち該ベンゾフラン−スチリル化合物を電子写真感光体の電荷移動物質として用いれば、広い共役系を有することによって、電荷移動度を高くして電子写真感光体の残留電位特性を向上させることができる。またバインダポリマとの相溶性に優れていることによって、感光層中に多量に含有させて電子写真感光体の光感度を向上させることができる。さらに結晶として析出しにくいことによって、電子写真感光体の繰返し使用時の特性を安定させることができる。
【００３４】
また本発明は、下記一般式（Ｖ）で示されるベンゾ［ｂ］フランアルデヒド化合物と、下記一般式（ＶＩ）で示されリン試薬とを反応させて、下記一般式（Ｉ）で示されるベンゾフラン−スチリル化合物を生成することを特徴とするベンゾフラン−スチリル化合物の製造方法である。
【００３５】
【化１４】

【００３６】
（式中、Ａｒ_１は置換基を含んでもよいアリレン基または置換基を含んでもよい２価の複素環基を示す。Ａｒ_２は、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基または置換基を含んでもよいアラルキル基を示す。Ａｒ_３およびＡｒ_４は、各々、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基、置換基を含んでもよいアラルキル基、置換基を含んでもよい炭素数１〜３のアルキル基または水素原子を示す。ａは置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示し、ｎは１〜４の整数を示す。ただしｎが２以上のとき、複数のａは同一でも異なってもよく、互いに環を形成してもよい。）
【００３７】
【化１５】

【００３８】
（式（Ｖ）中、Ａｒ_１、Ａｒ_２、ａおよびｎは、一般式（Ｉ）において示したものと同義である。
【００３９】
【化１６】

【００４０】
（式（ＶＩ）中、Ａｒ_３およびＡｒ_４は、一般式（Ｉ）において示したものと同義である。Ａｒ_５は、置換基を含んでもよいアリール基、置換基を含んでもよいアラルキル基または置換基を含んでもよい炭素数１〜３のアルキル基を示す。
【００４１】
本発明に従えば、前記ベンゾ［ｂ］フランアルデヒド化合物とリン試薬とを反応することによって、電子写真感光体の電荷移動物質として優れるベンゾフラン−スチリル化合物を、極めて容易に高収率で製造することができる。
【００４２】
【発明の実施の形態】
以下、本発明の実施の形態について説明する。
【００４３】
本発明によるベンゾフラン−スチリル化合物は、下記一般式（Ｉ）で示される。
【００４４】
【化１７】

【００４５】
一般式（Ｉ）中、Ａｒ_１は、置換基を含んでもよいアリレン基または置換基を含んでもよい２価の複素環基を示す。
【００４６】
Ａｒ_１の具体例としては、フェニレン基、ナフチレン基およびピリジレン基などが挙げられる。
【００４７】
前記一般式（Ｉ）中、Ａｒ_２は、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基、置換基を含んでもよいアラルキル基を示す。
【００４８】
Ａｒ_２の具体例としては、フェニル、トリル、メトキシフェニル、ナフチル、ピレニルおよびビフェニルなどのアリール基、ベンゾフリル、ベンゾチアゾリル、ベンゾオキサゾリルおよびＮ−エチレンカルバゾリルなどの複素環基、メチルベンジル、メトキシベンジルおよび２−チエニルメチルなどのアラルキル基が挙げられる。
【００４９】
前記一般式（Ｉ）中、Ａｒ_３およびＡｒ_４は、置換基を含んでもよいアリール基、置換基を含んでもよい複素環基、置換基を含んでもよいアラルキル基、置換基を含んでもよい炭素数１〜５のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基または水素原子を示す。
【００５０】
Ａｒ_３およびＡｒ_４の具体例としては、フェニル、トリル、メトキシフェニル、ナフチル、ピレニルおよびビフェニルなどのアリール基、ベンゾフリル、ベンゾチアゾリル、ベンゾオキサゾリルおよびＮ−エチルカルバゾリルなどの複素環基、メチルベンジル、メトキシベンジルおよび２−チエニルメチルなどのアラルキル基、メチル、エチルおよびｎ−プロピルなどのアルキル基、トリフルオロメチルなどのパーフルオロアルキル基、ならびに１、１、１−トリフルオロエチルなどのフルオロアルキル基、または水素原子が挙げられる。
【００５１】
また前記一般式（Ｉ）中、ａは、置換基を含んでもよい炭素数１〜３のアルキル基、置換基を含んでもよい炭素数１〜５のフルオロアルキル基、置換基を含んでもよい炭素数１〜５のパーフルオロアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のジアルキルアミノ基、ハロゲン原子または水素原子を示す。
【００５２】
ａの具体例としては、メチル、エチル、ｎ−プロピルおよびイソプロピルなどのアルキル基、メトキシ、エトキシ、ｎ−プロポキシおよびイソプロポキシなどのアルコキシ基、ジメチルアミノ、ジエチルアミノおよびジイソプロピルアミノなどのジアルキルアミノ基、ならびにフッ素、塩素および臭素などのハロゲン原子などが挙げられる。一般的に電子供与性の置換基が好ましい。
【００５３】
さらに前記一般式（Ｉ）中、ｎは、１，２，３または４を示す。ただしｎが２以上の場合、前述のａは、複数のａが同一であっても異なってもよく、互いに環を形成してもよい。
【００５４】
特に、一般式（Ｉ）で示されるベンゾフラン−スチリル化合物のうち、電子写真感光体に用いる上での電子写真特性、原価および製造などの観点から優れたものとして、Ａｒ_１がフェニレン基またはナフチレン基、Ａｒ_２がフェニル基、ｐ−メチルフェニル基またはナフチル基、Ａｒ３およびＡｒ４において、一方がフェニル基、ｐ−メチルフェニル基もしくはナフチル基、他方が水素原子、または共にフェニル基もしくはｐ−メチルフェニル基、ならびに、ａが水素原子であるものが挙げられる。
【００５５】
前記一般式（Ｉ）で示される本発明によるベンゾフラン−スチリル化合物の具体例としては、たとえば以下の表１〜表３に示す構造を有するベンゾフラン−スチリル化合物が挙げられるが、これによって本発明によるベンゾフラン−スチリル化合物が限定されるものではない。
【００５６】
【表１】

【００５７】
【表２】

【００５８】
【表３】

【００５９】
本発明によるベンゾフラン−スチリル化合物は、たとえば以下のようにして容易に製造することができる。
【００６０】
まず下記一般式（Ｖ）で示されるベンゾ［ｂ］フランアルデヒド化合物と、下記一般式（ＶＩ）で示されるリン試薬とを、塩基性条件下で反応させることによって、本発明によるベンゾフラン−スチリル化合物を合成することができる。
【００６１】
【化１８】

【００６２】
【化１９】

【００６３】
一般式（Ｖ）中、Ａｒ_１、Ａｒ_２、ａおよびｎは、一般式（Ｉ）において示したものと同義である。
【００６４】
一般式（ＶＩ）中、Ａｒ_３およびＡｒ_４は、一般式（Ｉ）において示したものと同義である。Ａｒ_５は、置換基を含んでもよいアリール基、置換基を含んでもよいアラルキル基または置換基を含んでもよい炭素数１〜３のアルキル基を示す。
【００６５】
この塩基条件下での反応は、たとえばジエチルエーテル、テトラヒドロフラン、エチレングリコール、ジメチルエーテルおよびジメチルスルホキシドなどの溶剤中、前記一般式（Ｖ）で示されるホルミルベンゾ［ｂ］フラン化合物１．０当量と、前記一般式（ＶＩ）で示されるリン試薬１．０〜１．２当量とを、カリウム−ｔ−ブトキサイドおよびナトリウムエトキサイドなどの金属アルコキシド塩基１．０〜１．５当量とともに、室温〜６０℃で２〜８時間加熱撹拌して行われる。
【００６６】
本発明による電子写真感光体は、感光層の電荷移動物質として、前述のベンゾフラン−スチリル化合物を１種類以上含有し、場合によっては他の電荷移動物質として、スチリル化合物、ヒドラゾン化合物およびトリフェニルアミン化合物などを含有してもよい。スチリル化合物としては、たとえばβ−フェニル−［４−（ベンジルアミノ）］スチルベン、β−フェニル−［４−（Ｎ−エチル−Ｎ−フェニルアミノ）］スチルベンおよび１，１−ビス（４−ジエチルアミノフェニル）−４，４−ジフェニルブタジエンなどが挙げられる。ヒドラゾン化合物としては、たとえば４−（ジベンジルアミノ）ベンズアルデヒド−Ｎ，Ｎ−ジフェニルヒドラゾン、４−（エチルフェニルアミノ）ベンズアルデヒド−Ｎ，Ｎ−ジフェニルヒドラゾン、４−（Ｎ，Ｎ−ビス（ｐ−トリル）アミノ）ベンズアルデヒド−Ｎ，Ｎ−ジフェニルヒドラゾンおよび３，３−ビス−（４’−ジエチルアミノフェニル）−アクロレイン−Ｎ，Ｎ−ジフェニルヒドラゾンなどが挙げられる。トリフェニルアミン化合物としては、たとえば４−メトキシ−４’−（４−メトキシスチリル）トリフェニルアミンおよび４−メトキシ−４’−スチリルトリフェニルアミンなどが挙げられる。
【００６７】
本発明による電子写真感光体の層構成は、以下に示すような種々の態様をとることができる。
【００６８】
図１は、電荷発生層５上に電荷移動層６を有する機能分離型感光層を有する電子写真感光体の一例を模式的に示す断面図である。導電性支持体１上に、感光層４として電荷発生物質２を主成分としてバインダポリマ中に分散させた電荷発生層５と、電荷移動物質３を主成分としてバインダポリマ中に分散させた電荷移動層６との積層から成る機能分離型感光体である。電荷発生層５の表面に電荷移動層６が形成され、この電荷移動層６中に電荷移動物質３として、本発明によるベンゾフラン−スチリル化合物が含有される。
【００６９】
図２は、電荷移動層６上に電荷発生層５を有する機能分離型感光層である。図１と同様の電荷発生層５と、電荷移動層６との積層から成る機能分離型感光体であるが、図１とは逆に電荷移動層６の表面に電荷発生層５が形成され、この電荷移動層６中に電荷移動物質３として、本発明によるベンゾフラン−スチリル化合物が含有される。
【００７０】
図３は、分散型感光層を有する電子写真感光体の一例を模式的に示す断面図である。導電性支持体１上に、感光層４として電荷発生層２と電荷移動層物質３とをバインダ中に分散させた単層から成る単層型感光体の構成を示す。
【００７１】
図４は、図３の電子写真感光体において表面保護層７を有する例を示す断面図である。導電性支持体１と図３と同様の感光層１４上に表面保護層７を設け、単層の感光層から成る単層型感光体の構成を示す。
【００７２】
図５は、図１の電子写真感光体において中間層８を有する例を示す断面図である。導電性支持体１と図１と同様の感光層４との間に中間層８を設け、積層の感光層から成る機能分離型感光体の構成を示す。
【００７３】
前述のベンゾフラン−スチリル化合物を電子写真感光体に用いるには、種々の方法が考えられる。たとえば、図１のように電荷発生効率の高い電荷発生層５と電荷移動層６とから成る積層構造の形態において、導電性支持体１上に増感染料、アゾ系顔料およびフタロシアニン系顔料を代表とする顔料を主体とする電荷発生層５を設ける。該電荷発生層５上に、前述のベンゾフラン−スチリル化合物を、必要に応じて酸化防止剤や電子吸引性化合物を添加して、バインダポリマ中に溶解または分散させた電荷移動層を設けて成る積層型の機能分離型感光体とする。また前述のベンゾフラン−スチリル化合物と増感染料とを、必要に応じて化学増感剤や電子吸引性化合物を添加して、バインダポリマ中に溶解または分散させた塗布液を、図３のように導電性支持体１上に塗布して成る単層型感光体とする。このように本発明によるベンゾフラン−スチリル化合物は、これらのいずれの場合にも適用することが可能である。
【００７４】
本発明によるベンゾフラン−スチリル化合物を用いて感光体を作製するに際しては、金属ドラム、金属板、導電性加工を施した紙およびプラスチックフィルムなどの支持体上へ、バインダポリマの助けを借りて被膜にする。この場合、さらに感度を上げるためには、後述するような、増感剤およびバインダポリマに対する可塑性を付与する物質を加えて、均一な感光体被膜にすることが望ましい。
【００７５】
前記バインダポリマとしては、利用分野に応じて種々のものが挙げられる。すなわち複写機用またはプリンタ用感光体の分野では、ポリスチレン樹脂、ポリビニルアセタール樹脂、ポリスルホン樹脂、ポリカーボネート樹脂、ポリフェニレンオキサイド樹脂、ポリエステル樹脂、アルキッド樹脂およびポリアリレート樹脂などが望ましい。これらの樹脂は、単独または２種以上混合して用いてもよい。特にポリスチレン樹脂、ポリカーボネート樹脂、ポリアリレート樹脂およびポリフェニレンオキサイド樹脂などは、体積抵抗値が１０^１３Ω以上で、また、被膜性および電位特性などにも優れている。
【００７６】
これらのバインダポリマの添加量は、前述のベンゾフラン−スチリル化合物に対して、重量比で０．２〜２０倍の割合が好ましく、より好ましくは０．５〜５倍の範囲である。０．２倍未満になるとベンゾフラン−スチリル化合物が感光体表面から析出してくるという欠点が生じ、２０倍を超えると著しい感度低下をまねく。
【００７７】
印刷版に使用するためには、特にアルカリ性バインダポリマが必要である。アルカリ性バインダポリマとは、水もしくは水との混合系を含むアルコール性のアルカリ性溶剤に可溶な酸性基を有する高分子物質である。可溶な酸性基としては、たとえば酸無水物基、カルボキシル基、フェノール性水酸基、スルホン酸基、スルホンアミド基およびスルホンイミド基などである。これらのアルカリ性バインダポリマは、通常、酸価が１００以上の高い値をもっていることが好ましい。酸価の大きなバインダポリマは、アルカリ性溶剤に易溶または容易に潤滑化する。そのようなバインダポリマとしては、たとえばスチレン：無水マレイン酸共重合体、酢酸ビニル：無水マレイン酸共重合体、酢酸ビニル：クロトン酸共重合体、メタクリル酸：メタクリル酸エステル共重合体、フェノール樹脂およびメタクリル酸：スチレン：メタクリル酸エステル共重合体などである。これらの樹脂は、光導電性有機物質に対して、複写機感光体の場合と同程度の割合で加える。
【００７８】
前記増感染料としては、メチルバイオレット、クリスタルバイオレット、ナイトブルーおよびビクトリアブルーなどで代表されるトリフェニルメタン系染料、エリスロシン、ローダミンＢ、ローダミン３Ｒ、アクリジンオレンジおよびフラペオシンなどに代表されるアクリジン染料、メチレンブルーおよびメチレングリーンなどに代表されるチアジン染料、カプリブルーおよびメルドラブルーなどに代表されるオキサジン染料、その他シニアン染料、スチリル染料、ピリリウム塩染料、ならびにチオピリリウム塩染料などがある。
【００７９】
また感光層において、光吸収によって極めて高い効率で電荷を発生させる光導電性の顔料としては、各種金属フタロシアニン、無金属フタロシアニンおよびハロゲン化無金属フタロシアニンなどのフタロシアニン系顔料、ペリレンイミドおよびペリレン酸無水物などのペリレン酸顔料、ビスアゾ系顔料およびトリスアゾ系顔料などのアゾ系顔料、その他キナクリドン系顔料、ならびにアントラキノン系顔料などがある。特に電荷を発生する顔料に、無金属フタロシアニン顔料、チタニルフタロシアニン顔料、フロレンやフロレノン環を含有するビスアゾ顔料、芳香族アミンから成るビスアゾ顔料、トリスアゾ顔料を用いたものは高い感度を示す優れた電子写真感光体を与える。
【００８０】
また前記増感染料を電荷発生物質として用いてもよい。前述の染料は、単独で使用してもよいが、顔料を共存させることによってさらに高い効率で電荷を発生させる場合が多い。
【００８１】
前述のような増環剤とは別に、繰返し使用に対しての残留電位の増加、帯電電位の低下および感度の低下などを防止する目的で、種々の化学部質を添加する必要が生じる場合がある。これらのための添加物質としては、１−クロルアントラキノン、ベンゾキノン、２，３−ジクロロナフトキノン、ナフトキノン、４，４’−ジニトロベンゾフェノン、４，４’−ジクロロベンゾフェノン、４−ニトロベンゾフェノン、４−ニトロベンザルマロンジニトリル、α−シアノ−β−（ｐ−シアノフェニル）アクリル酸エチル、９−アントラセニルメチルマロンジニトリル、１−シアノ−１−（ｐ−ニトロフェニル）−２−（ｐ−クロルフェニル）エチレンおよび２，７−ジニトロフルオレノンなどの電子吸引性化合物が挙げられる。その他、感光体中への添加物として、酸化防止剤、カール防止剤およびレベリング剤などを必要に応じて添加することができる。
【００８２】
本発明によるベンゾフラン−スチリル化合物は、前述のような感光体の形態に応じて前述の種々の添加物質とともに、適当な溶剤中に溶解または分散して塗布液を調製し、その塗布液を導電性支持体１上に塗布して乾燥することによって、感光体を製造する。塗布液の溶剤としては、ベンゼン、トルエン、キシレンおよびモノクロルベンゼンなどの芳香族炭化水素、ジクロロメタンおよびジクロロエタンなどのハロゲン化炭化水素、テトラヒドロフラン、ジオキサン、ジメトキシメチルエーテル、ならびにジメチルホルムアミドなどの単独溶剤または２種以上の混合溶剤が挙げられる。これらの溶剤には、必要に応じてアルコール類、アセトニトリルおよびメチルエチルケトンなどの溶剤をさらに加えて使用することができる。
【００８３】
導電性支持体１と感光層４または１４との間に設けられる中間層８は、保護機能や接着機能を付与し、塗工性を高め、さらには基盤から感光層への電荷注入改善を目的としたものであり、このような材料としては、カゼイン、ポリビニルブチラール、ポリビニルアルコール、ニトロセルロース、エチレン−アクリル酸コポリマー、ポリアミド、ポリウレタン、ゼラチンおよび酸化アルミニウムなどが適当である。ポリアミドとしては、ナイロン６、ナイロン６６、ナイロン６１０、共重合ナイロンおよびアルコキシメチル化ナイロンなどが挙げられる。
【００８４】
以下、本発明によるベンゾフラン−スチリル化合物の製造例および本発明による電子写真感光体について、実施例に基づいて具体的に説明する。本発明はこれにより何ら限定されるものではない。
【００８５】
（製造例）
ベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）を製造した。
【００８６】
カリウム−ｔ−ブトキサイド０．８１ｇ（１．５当量）をテトラヒドロフラン５ｍｌに溶解し、水浴にて０℃に冷却した。この溶液に、α、α’−ジフェニルベンジルホスホン酸ジエチル１．９ｇ（１．３当量）をテトラヒドロフラン５ｍｌに溶解した溶液を、徐々に加えた。約１０分間０℃で撹拌し、安定Ｗｉｔｔｉｇイリドを生成させた。この溶液に、５−フォルミル−２−（４’（ビス（ｐ−トリル）アミノ）フェニル）ベンゾ［ｂ］フラン２．０ｇ（１．０当量）をテトラヒドロフラン１０ｍｌに溶解した溶液を徐々に加えた。水浴を外し、室温まで反応温度を上げ、約２時間撹拌を続けた。
【００８７】
薄層クロマトグラフィーにて反応の終了を確認し、常法の抽出処理を行って目的のベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）２．５８ｇを得た。収率は９５％であった。
【００８８】
このようにして得れらたベンゾフラン−スチリル化合物（例示化合物Ｎｏ１）の構造は、^１Ｈ−ＮＭＲ、通常^１３Ｃ−ＮＭＲおよびＤＥＰＴ１３５ ^１３Ｃ−ＮＭＲを測定することにより確認した。
【００８９】
図６は、重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）の^１Ｈ−ＮＨＲスペクトルである。図７は、重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）の通常^１３Ｃ−ＮＭＲスペクトルである。図８は、重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）のＤＥＰＴ１３５での^１３Ｃ−ＮＭＲスペクトルである。これらのＮＭＲシグナルは、目的とするベンゾフラン−スチリル化合物（例示化合物Ｎｏ１）の構造をよく支持している。
【００９０】
（実施例１〜４、比較例）
図１に示した電荷移動層６に、電荷移動物質３として、例示化合物Ｎｏ１、５、１４および２１で示したベンゾフラン−スチリル化合物を、それぞれ含有する実施例１、２，３および４、ならびに従来公知の４−（ジエチルアミノ）−ベンズアルデヒド−Ｎ，Ｎ−ジフェニルヒドラゾンを含有する比較例の５種類の積層型の電子写真感光体を製造した。
【００９１】
フェノキシ樹脂（ＰＫＨＨ：ユニオンカーバイド社製）の１％ＴＨＦ（テトラヒドロフラン）溶液中に、下記構造式（ＶＩＩ）で示されるビスアゾ顔料を、重量比で樹脂と同量加え、ペイントコンディショナ（レッドデビル社製）の中で直径１．５ｍｍのガラスビーズとともに約２時間分散し、電荷発生層用塗布液を調製した。調製した電荷発生層用塗布液を、ドクターブレイド法により、アルミニウム蒸着のポリエステルフィルム（膜厚８０μｍ）の支持体上に塗布して乾燥し、電荷発生層を形成した。乾燥後の電荷発生層の膜厚は０．２μｍであった。
【００９２】
【化２０】

【００９３】
例示化合物Ｎｏ１、４、１２もしくは２３で示したベンゾフラン−スチリル化合物、または４−（ジエチルアミノ）−ベンズアルデヒド−Ｎ，Ｎ−ジフェニルヒドラゾンを１ｇと、ポリアリレート樹脂（Ｕ−１００：ユニチカ社製）１．２ｇとを、ＴＨＦに溶解した１５％溶液を調製し、５種類の電荷移動層用塗布液とした。各電荷移動層用塗布液を、前述のようにして形成した電荷発生層上に、スキージングドクタにより塗布して乾燥し、乾燥膜厚２５μｍの樹脂−ビスアミン化合物固溶相である電荷移動層をそれぞれ形成し、実施例１〜４および比較例１の５種類の積層型電子写真感光体を作製した。
【００９４】
前述のようにして作成した積層型電子写真感光体について、その電子写真特性を静電記録紙試験装置（ＳＰ−４２８：川口電機社製）により評価した。加電圧：−６ｋＶおよびスタティック：Ｎｏ．３の測定条件で、白色光照射（照射光：５ルックス）による−７００Ｖから−１００Ｖに減衰させるために要する露光量Ｅ１００（ルックス・秒）および初期電位Ｖ０（−ボルト）を測定した。さらに前記静電記録紙試験装置を用いて、加電−除電（除電光：４０ルックスの白色光を１秒間照射）を１サイクルとして１万回同様に操作した後の露光量Ｅ１００（ルックス・秒）および初期電位Ｖ０（−ボルト）を測定した。これらの１回目および１万回目におけるＥ１００およびＶ０の測定結果を表４に示す。
【００９５】
【表４】

【００９６】
表４より、本発明によるベンゾフラン−スチリル化合物を用いた実施例１〜４は、従来化合物を用いた比較例１と比較して感度だけでなく繰返し特性も良好であることがわかった。
【００９７】
（実施例５）
図１に示した電荷移動層６に、電荷移動物質３として、例示化合物Ｎｏ．３に示したベンゾフラン−スチリル化合物を含有する実施例５の積層型の電子写真感光体を製造した。
【００９８】
下記構造式（ＶＩＩＩ）で示されるｘ型無金属フタロシアニン（ファストゲンブルー８１２０：大日本インキ社製）０．４ｇを、塩化ビニル：酢酸ビニル共重合体樹脂（エスレックスＭ：積水化学社製）０．３ｇを溶かした酢酸エチル溶液３０ｍｌ中に加え、ペイントコンディショナ中で約２０分間分散し、電荷発生層用塗布液を調製した。調製した電荷発生層用塗布液を、ドクターブレイド法により、アルミニウム蒸着のポリエステルフィルムの支持体上に塗布して乾燥し、乾燥後の電荷発生層の膜厚が０．４μｍになるように電荷発生層を形成した。
【００９９】
【化２１】

【０１００】
この電荷発生層上に、例示化合物Ｎｏ．２のベンゾフラン−スチリル化合物を重量比５０％で含有するポリアリレート層の電荷移動層を積層して２層からなる実施例５の積層型電子写真感光体を作製した。
【０１０１】
実施例５の感光体の７８０ｎｍの光を用いて電位半減に要したエネルギ（Ｅ５０）および初期電位（−Ｖ０）を求めたところ、Ｖ０＝−６９０（ボルト）およびＥ５０＝０．２１（μＪ）で非常に高感度、かつ高帯電性の感光体であった。
【０１０２】
また、レーザプリンタ（ＷＤ−５８０Ｐ：シャープ社製）を改造し、ドラム部に実施例５の感光体を張付け、連続空コピー（Ｎｏｎ Ｃｏｐｙ Ａｇｉｎｇ）を１万回を行った後、その初期電位低下および感度低下の度合を調べた。その結果、Ｖ０＝−６８０（ボルト）およびＥ５０＝０．２２（μＪ）で、第１回目と比べてほとんど値の変動がみられなかった。
【０１０３】
（実施例６〜９）
図３に示した電荷移動物質３として、例示化合物Ｎｏ．６、８、１３または２４に示したベンゾフラン−スチリル化合物を含有する単一層の感光層１４を有する４種類の電子写真感光体を製造した。
【０１０４】
例示化合物Ｎｏ６、８、１３または２４の１ｇ、下記構造式（ＩＸ）で示されるポリカーボネート樹脂１．１ｇ、Ｎ，Ｎ−３，５−キシリル−３，４，９，１０−ペリレンテトラカルボキシルイミド０．１５ｇおよび紫外線吸収剤０．０５ｇを、塩化メチレン１４．０ｍｌに溶かした感光層用塗布液を調製した。なお該感光層用塗布液においてイミド化合物は一部分散状態であった。調製した感光層用塗布液をアプリケータによりアルミニウム基盤表面をアルマイト加工（アルマイト層：７μｍ）した支持体上に塗布して乾燥し、乾燥後の感光層膜厚２０μｍの単層型感光体を得た。
【０１０５】
【化２２】

【０１０６】
前述のようにして作製した単層型電子写真感光体について、その電子写真特性を前記静電記録紙試験装置により評価した。加電圧：５．５ｋＶおよびスタティック：Ｎｏ．３の測定条件で、白色光照射（照射光：５ルックス）による＋７００Ｖから＋１００Ｖに減衰させるために要する露光量Ｅ１００（ルックス・秒）を測定した。また、１万回の連続空コピーを行い、感度（Ｅ１００）低下の度合を調べた。これらの１回目および１万回目におけるＥ１００の測定結果を表５に示す。
【０１０７】
【表５】

【０１０８】
表５より、本発明によるベンゾフラン−スチリル化合物を用いた実施例６〜９の感光体は、正帯電においても優れた感度および繰返し特性を有する感光体であることが判った。
【０１０９】
【発明の効果】
以上のように本発明によれば、広い共役系を有し、バインダポリマとの相溶性に優れ、結晶として析出しにくいという特徴を有することによって、高感度かつ高耐久性を有する電子写真感光体用の電荷移動物質として用いることができる化合物、すなわちベンゾフラン骨格を有する新規なベンゾフラン−スチリル化合物を提供することができる。
【０１１０】
また本発明によれば、ベンゾ［ｂ］フランアルデヒド化合物とリン試薬とを反応することによって、電子写真感光体の電荷移動物質として優れるベンゾフラン−スチリル化合物を、極めて容易に高収率で製造する製造方法を提供することができる。
【０１１１】
したがって本発明によれば、電荷移動物質として前記ベンゾフラン−スチリル化合物を含有することによって、有機系で高感度かつ高耐久性を有し、無機系に比べて無毒で資源的にも問題がなく、透明性が高く軽量で成膜性にも優れ、正負の両帯電性を有して製造も容易で、繰返し使用でも光感度の低下がほとんど起こらない優れた特性を備える電子写真感光体を提供することができる。
【図面の簡単な説明】
【図１】電荷発生層５上に電荷移動層６を有する機能分離型感光層を有する電子写真感光体の一例を模式的に示す断面図である。
【図２】電荷移動層６上に電荷発生層５を有する機能分離型感光層である。
【図３】分散型感光層を有する電子写真感光体の一例を模式的に示す断面図である。
【図４】図３の電子写真感光体において表面保護層７を有する例を示す断面図である。
【図５】図１の電子写真感光体において中間層８を有する例を示す断面図である。
【図６】重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）の^１Ｈ−ＮＨＲスペクトルである。
【図７】重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）の通常^１３Ｃ−ＮＭＲスペクトルである。
【図８】重クロロホルム中でのベンゾフラン−スチリル化合物（例示化合物Ｎｏ．１）のＤＥＰＴ１３５での^１３Ｃ−ＮＭＲスペクトルである。
【符号の説明】
１ 導電性支持体
２ 電荷発生物質
３ 電荷移動物質
４，１４ 感光層
５ 電荷発生層
６ 電荷移動
７ 表面保護層
８ 中間層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photoreceptor used in an electrophotographic process, a benzofuran-styryl compound suitably used for the electrophotographic photoreceptor, and a method for producing the same.
[0002]
[Prior art]
The electrophotographic technology has immediacy and can provide high-quality images. In recent years, the electrophotographic technology has been used not only in the field of copying machines but also in the field of various printers, and its application range has been expanding. In the field of electrophotographic photoreceptors (hereinafter, also simply referred to as “photoreceptors”), as the photoconductive material, inorganic materials such as selenium, arsenic, selenium alloy, selenium-tellurium alloy, cadmium sulfide, and zinc oxide have long been used. Material was used. However, in recent years, instead of such inorganic materials, an organic photoreceptor mainly composed of an organic photoconductive material having advantages such as no pollution, good film formability and ease of production has been developed. It became so.
[0003]
Among organic photoconductors, a so-called stacked photoconductor in which a charge generation layer composed of a charge generation material and a charge transfer layer composed of a charge transfer material are sequentially laminated has been devised, and has become a mainstream of research. I have. That is, in the stacked photoreceptor, by combining a charge generation material that can efficiently configure a desired charge generation layer and a charge transfer material that can efficiently configure a desired charge transfer layer,
1. That a more sensitive photoreceptor can be obtained,
2. A wide selection of materials and a highly safe photoreceptor can be obtained.
3. High productivity of coating and relatively cost-effective
For this reason, photoconductors have become mainstream. Copiers having high printing durability and high-speed performance, such as a printing durability of 200,000 copies or more and a copy speed per minute of 70 or more, are commercially available.
[0004]
As described above, there are photoconductors having excellent performance among the organic laminated photoconductors that have been put into practical use, but most of them have various problems related to photoconductor production in pursuit of the performance. It is the present situation that still has a point.
[0005]
Among those specific problems, some related to charge transfer materials are listed below.
1. Low compatibility with the binder polymer,
2. Crystals are easy to precipitate,
3. Change in sensitivity when used repeatedly,
4. Poor charging ability and repetition characteristics,
5. Poor residual potential characteristics,
And the like.
[0006]
A typical example of such charge transfer materials can be classified according to their structural characteristics. First, an arylene group (mostly a simple phenylene group in the early stages of its development) was initially used as its central nucleus. The hydrazone type (Japanese Patent Application Laid-Open No. 54-59143), the stilbene-styryl type (Japanese Patent Application Laid-Open No. 58-198043) and the triarylamine type (Japanese Patent Publication No. 58-32372) have been energetically studied. . Then, a series of compounds having a monocyclic heterocyclic ring system at its central nucleus, phenothiazine, triazole, quinoxaline, oxadiazole, oxazole, pyrazoline, dihydronicotinamide compounds, indoline compounds and semicarbazones Compounds have been developed. Recently, pyrene derivatives, naphthalene derivatives, phenanthrene derivatives (JP-A-5-148209) and the like having a condensed polycyclic hydrocarbon system at the central nucleus thereof have been developed.
[0007]
[Problems to be solved by the invention]
As described above, despite the fact that many organic compounds have been developed as charge transfer materials, none of the organic compounds satisfy all of the above-mentioned problems, and the basic properties required for photoreceptors, At present, a material which sufficiently satisfies the mechanical strength and high durability has not yet been obtained.
[0008]
In the case of a phenanthrene derivative, when synthesizing the derivative,
1. The phenanthrene-9-carbaldehyde putative starting material is very expensive,
2. A compound in which two identical side chains are inevitably introduced as a by-product when the first side chain is introduced, since the linking portions of the mother nucleus for sequentially introducing the hydrazone portion and the styryl portion are both the same aldehyde group. Is generated, it takes time to purify the compound, and the reaction yield decreases,
Various problems are pointed out.
[0009]
An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability, a novel benzofuran-styryl compound having a benzo [b] furan skeleton used as a charge transfer material thereof, and efficient production thereof. Is to provide a way.
[0010]
[Means for Solving the Problems]
The present invention relates to an electrophotographic photosensitive member, characterized in that a photosensitive layer provided on a conductive support contains a benzofuran-styryl compound represented by the following general formula (I) as a charge transfer material. is there.
[0011]
Embedded image

[0012]
(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.)
[0013]
According to the present invention, an electrophotographic photosensitive member having high sensitivity and high durability can be provided by containing a benzofuran-styryl compound represented by the general formula (I) as a charge transfer material. That is, since the benzofuran-styryl compound has a wide conjugated system, the charge mobility can be increased to improve the residual potential characteristics of the electrophotographic photosensitive member. Further, since the benzofuran-styryl compound has excellent compatibility with the binder polymer, the benzofuran-styryl compound can be contained in a large amount in the photosensitive layer to improve the photosensitivity of the electrophotographic photosensitive member. Further, since the benzofuran-styryl compound hardly precipitates as crystals, the characteristics of the electrophotographic photoreceptor when used repeatedly can be stabilized.
[0014]
Further, the present invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (II).
[0015]
Embedded image

[0016]
(In the formula, b is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and m represents an integer of 1 to 4. However, when m is 2 or more, B may be the same or different. Ar ₂ , Ar ₃ , Ar ₄ , a and n have the same meanings as those shown in formula (I).)
[0017]
According to the present invention, by including a benzofuran-styryl compound represented by the general formula (II) having the same characteristics as the general formula (I) as a charge transfer material, an electrophotographic photosensitive material having high sensitivity and high durability can be obtained. Body can be provided.
[0018]
Further, the invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (III).
[0019]
Embedded image

[0020]
(In the formula, d is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent. Represents a fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and l represents an integer of 1 to 5. However, when l is 2 or more, May be the same or different. Ar ₃ , Ar ₄ , a, b, n, and m have the same meanings as those shown in formula (II).)
[0021]
According to the present invention, by containing a benzofuran-styryl compound represented by the general formula (III) having the same properties as the general formula (I) as a charge transfer material, an electrophotographic photosensitive material having high sensitivity and high durability can be obtained. Body can be provided.
[0022]
Further, the present invention is characterized in that the benzofuran-styryl compound is a compound represented by the following general formula (IV).
[0023]
Embedded image

[0024]
(Wherein, e is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and a peralkyl group having 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and k represents an integer of 1 to 5. However, when k is 2 or more, May be the same or different. Ar ₃ , Ar ₄ , a, b, n, and m have the same meanings as those shown in formula (III).)
[0025]
According to the present invention, by containing a benzofuran-styryl compound represented by the general formula (IV) having the same properties as the general formula (I) as a charge transfer material, an electrophotographic photosensitive material having high sensitivity and high durability can be obtained. Body can be provided.
[0026]
Further, the invention is characterized in that the photosensitive layer has a laminated structure of a charge generation layer containing a charge generation material and a charge transfer layer containing the charge transfer material.
[0027]
According to the present invention, the charge transfer layer of the photosensitive layer having a laminated structure contains the benzofuran-styryl compound as a charge transfer material, thereby providing a laminated electrophotographic photosensitive member having high sensitivity and high durability. be able to.
[0028]
Further, the invention is characterized in that the photosensitive layer comprises a single layer containing a charge generation material and the charge transfer material.
[0029]
According to the present invention, a single-layer type electrophotographic photoreceptor having excellent sensitivity and repetition characteristics even under positive charging is provided by including the benzofuran-styryl compound as a charge transfer material in a single-layer photosensitive layer. can do.
[0030]
The present invention is a benzofuran-styryl compound represented by the following general formula (I).
[0031]
Embedded image

[0032]
(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.)
[0033]
According to the present invention, the benzofuran-styryl compound represented by the general formula (I) has a feature that it has a wide conjugated system, is excellent in compatibility with the binder polymer, and hardly precipitates as a crystal. Further, it is possible to provide a compound which can be used as a charge transfer material for an electrophotographic photosensitive member having high durability. That is, if the benzofuran-styryl compound is used as a charge transfer material for an electrophotographic photoreceptor, it has a wide conjugated system, so that the charge mobility can be increased and the residual potential characteristics of the electrophotographic photoreceptor can be improved. In addition, due to its excellent compatibility with the binder polymer, it can be contained in a large amount in the photosensitive layer to improve the photosensitivity of the electrophotographic photosensitive member. In addition, the characteristics of the electrophotographic photoreceptor during repeated use can be stabilized by the fact that it is difficult to precipitate as crystals.
[0034]
Further, the present invention provides a benzofuran represented by the following general formula (I) by reacting a benzo [b] furanaldehyde compound represented by the following general formula (V) with a phosphorus reagent represented by the following general formula (VI). -A method for producing a benzofuran-styryl compound, which comprises producing a styryl compound.
[0035]
Embedded image

[0036]
(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.)
[0037]
Embedded image

[0038]
(In the formula (V), Ar ₁ , Ar ₂ , a and n have the same meanings as those shown in the general formula (I).
[0039]
Embedded image

[0040]
(In the formula (VI), Ar ₃ and Ar ₄ have the same meanings as those shown in the general formula (I). Ar ₅ is an aryl group optionally having a substituent, an aralkyl group optionally having a substituent or It shows a C1-C3 alkyl group which may contain a substituent.
[0041]
According to the present invention, by reacting the benzo [b] furanaldehyde compound with a phosphorus reagent, a benzofuran-styryl compound excellent as a charge transfer material for an electrophotographic photoreceptor can be produced very easily in high yield. Can be.
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0043]
The benzofuran-styryl compound according to the present invention is represented by the following general formula (I).
[0044]
Embedded image

[0045]
In the general formula (I), Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent.
[0046]
Specific examples of Ar ₁ include a phenylene group, a naphthylene group, and a pyridylene group.
[0047]
In the general formula (I), Ar ₂ represents an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or an aralkyl group which may have a substituent.
[0048]
Specific examples of Ar ₂ include an aryl group such as phenyl, tolyl, methoxyphenyl, naphthyl, pyrenyl and biphenyl; a heterocyclic group such as benzofuryl, benzothiazolyl, benzoxazolyl and N-ethylenecarbazolyl; methylbenzyl; And aralkyl groups such as benzyl and 2-thienylmethyl.
[0049]
In the general formula (I), Ar ₃ and Ar ₄ represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, an aralkyl group which may have a substituent, and a carbon atom which may have a substituent. An alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, a perfluoroalkyl group having 1 to 5 carbon atoms which may have a substituent or a hydrogen atom.
[0050]
Specific examples of Ar ₃ and Ar ₄ include aryl groups such as phenyl, tolyl, methoxyphenyl, naphthyl, pyrenyl and biphenyl; heterocyclic groups such as benzofuryl, benzothiazolyl, benzoxazolyl and N-ethylcarbazolyl; Aralkyl groups such as benzyl, methoxybenzyl and 2-thienylmethyl, alkyl groups such as methyl, ethyl and n-propyl, perfluoroalkyl groups such as trifluoromethyl, and fluoroalkyl groups such as 1,1,1-trifluoroethyl Group, or a hydrogen atom.
[0051]
In the general formula (I), a is an alkyl group having 1 to 3 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, or a carbon atom which may have a substituent. A perfluoroalkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom.
[0052]
Specific examples of a include alkyl groups such as methyl, ethyl, n-propyl and isopropyl, alkoxy groups such as methoxy, ethoxy, n-propoxy and isopropoxy, dialkylamino groups such as dimethylamino, diethylamino and diisopropylamino, and And halogen atoms such as fluorine, chlorine and bromine. Generally, electron donating substituents are preferred.
[0053]
Further, in the general formula (I), n represents 1, 2, 3, or 4. However, when n is 2 or more, the above-mentioned a may be the same as or different from a plurality of a, and may form a ring with each other.
[0054]
In particular, among the benzofuran-styryl compounds represented by the general formula (I), Ar ₁ is preferably a phenylene group or a naphthylene group, which is excellent from the viewpoints of electrophotographic characteristics, cost, and production when used in an electrophotographic photoreceptor. , Ar ₂ is a phenyl group, a p-methylphenyl group or a naphthyl group, one of Ar3 and Ar4 is a phenyl group, a p-methylphenyl group or a naphthyl group, the other is a hydrogen atom, or both a phenyl group or a p-methylphenyl group , And those in which a is a hydrogen atom.
[0055]
Specific examples of the benzofuran-styryl compound according to the present invention represented by the general formula (I) include, for example, benzofuran-styryl compounds having the structures shown in Tables 1 to 3 below. -The styryl compound is not limited.
[0056]
[Table 1]

[0057]
[Table 2]

[0058]
[Table 3]

[0059]
The benzofuran-styryl compound according to the present invention can be easily produced, for example, as follows.
[0060]
First, a benzo [b] furanaldehyde compound represented by the following general formula (V) is reacted with a phosphorus reagent represented by the following general formula (VI) under basic conditions, whereby a benzofuran-styryl compound according to the present invention is obtained. Can be synthesized.
[0061]
Embedded image

[0062]
Embedded image

[0063]
In the general formula (V), Ar ₁ , Ar ₂ , a and n have the same meanings as those in the general formula (I).
[0064]
In the general formula (VI), Ar ₃ and Ar ₄ have the same meanings as those shown in the general formula (I). Ar ₅ represents an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkyl group having 1 to 3 carbon atoms which may have a substituent.
[0065]
The reaction under the basic conditions is carried out by, for example, using a solvent such as diethyl ether, tetrahydrofuran, ethylene glycol, dimethyl ether and dimethyl sulfoxide in a solvent such as 1.0 equivalent of the formylbenzo [b] furan compound represented by the general formula (V). 1.0 to 1.2 equivalents of the phosphorus reagent represented by the general formula (VI) together with 1.0 to 1.5 equivalents of a metal alkoxide base such as potassium-t-butoxide and sodium ethoxide at room temperature to 60 ° C. Heating and stirring are performed for 2 to 8 hours.
[0066]
The electrophotographic photoreceptor according to the present invention contains at least one kind of the above-mentioned benzofuran-styryl compound as a charge transfer substance of a photosensitive layer, and optionally contains a styryl compound, a hydrazone compound and a triphenylamine compound as other charge transfer substances. And the like. Examples of styryl compounds include β-phenyl- [4- (benzylamino)] stilbene, β-phenyl- [4- (N-ethyl-N-phenylamino)] stilbene and 1,1-bis (4-diethylaminophenyl) ) -4,4-diphenylbutadiene and the like. Examples of the hydrazone compound include 4- (dibenzylamino) benzaldehyde-N, N-diphenylhydrazone, 4- (ethylphenylamino) benzaldehyde-N, N-diphenylhydrazone, and 4- (N, N-bis (p-tolyl). ) Amino) benzaldehyde-N, N-diphenylhydrazone and 3,3-bis- (4'-diethylaminophenyl) -acrolein-N, N-diphenylhydrazone. Examples of the triphenylamine compound include 4-methoxy-4 ′-(4-methoxystyryl) triphenylamine and 4-methoxy-4′-styryltriphenylamine.
[0067]
The layer configuration of the electrophotographic photoreceptor according to the present invention can take various aspects as described below.
[0068]
FIG. 1 is a cross-sectional view schematically showing an example of an electrophotographic photosensitive member having a function-separated type photosensitive layer having a charge transfer layer 6 on a charge generation layer 5. A charge generation layer 5 having a charge generation substance 2 as a main component dispersed in a binder polymer as a photosensitive layer 4 on a conductive support 1 and a charge transfer having a charge transfer substance 3 dispersed in a binder polymer as a main component. This is a function-separated type photoconductor composed of a layer 6 and a layer 6. A charge transfer layer 6 is formed on the surface of the charge generation layer 5, and the charge transfer layer 6 contains the benzofuran-styryl compound according to the present invention as the charge transfer substance 3.
[0069]
FIG. 2 is a function-separated type photosensitive layer having the charge generation layer 5 on the charge transfer layer 6. 1 is a function-separated type photoreceptor formed by laminating a charge generation layer 5 and a charge transfer layer 6 similar to those in FIG. 1. The charge transfer layer 6 contains, as the charge transfer substance 3, the benzofuran-styryl compound according to the present invention.
[0070]
FIG. 3 is a cross-sectional view schematically illustrating an example of an electrophotographic photosensitive member having a dispersion-type photosensitive layer. The structure of a single-layer type photoreceptor comprising a single layer in which a charge generation layer 2 and a charge transfer layer substance 3 are dispersed in a binder as a photosensitive layer 4 on a conductive support 1 is shown.
[0071]
FIG. 4 is a cross-sectional view showing an example having the surface protective layer 7 in the electrophotographic photoreceptor of FIG. The surface protective layer 7 is provided on the conductive support 1 and the photosensitive layer 14 similar to that shown in FIG.
[0072]
FIG. 5 is a cross-sectional view showing an example having the intermediate layer 8 in the electrophotographic photoreceptor of FIG. An intermediate layer 8 is provided between the conductive support 1 and the photosensitive layer 4 similar to that shown in FIG.
[0073]
Various methods are conceivable for using the above-mentioned benzofuran-styryl compound in an electrophotographic photosensitive member. For example, as shown in FIG. 1, a sensitizing dye, an azo-based pigment, and a phthalocyanine-based pigment are typically formed on a conductive support 1 in the form of a laminated structure including a charge-generating layer 5 and a charge-transferring layer 6 having high charge generation efficiency. A charge generation layer 5 mainly composed of a pigment is provided. A lamination comprising a charge transfer layer formed by dissolving or dispersing the above-mentioned benzofuran-styryl compound in the binder polymer by adding an antioxidant or an electron-withdrawing compound, if necessary, on the charge generation layer 5. Function-separated type photoreceptor. Further, a coating solution in which the above-mentioned benzofuran-styryl compound and a sensitizing dye are dissolved or dispersed in a binder polymer by adding a chemical sensitizer or an electron-withdrawing compound as necessary, as shown in FIG. A single-layer photoreceptor formed by coating on the conductive support 1 is obtained. Thus, the benzofuran-styryl compound according to the present invention can be applied to any of these cases.
[0074]
In preparing a photoreceptor using the benzofuran-styryl compound according to the present invention, a metal drum, a metal plate, a support such as a conductively processed paper and a plastic film are coated on a support with the help of a binder polymer. I do. In this case, in order to further increase the sensitivity, it is desirable to add a sensitizer and a substance that imparts plasticity to the binder polymer, as described later, to form a uniform photoreceptor coating.
[0075]
As the binder polymer, various binder polymers may be used depending on the field of use. That is, in the field of photoconductors for copying machines or printers, polystyrene resins, polyvinyl acetal resins, polysulfone resins, polycarbonate resins, polyphenylene oxide resins, polyester resins, alkyd resins, polyarylate resins, and the like are desirable. These resins may be used alone or in combination of two or more. In particular, a polystyrene resin, a polycarbonate resin, a polyarylate resin, a polyphenylene oxide resin, and the like have a volume resistance of 10 ¹³ Ω or more and are excellent in film properties and potential characteristics.
[0076]
The amount of the binder polymer to be added is preferably 0.2 to 20 times by weight, more preferably 0.5 to 5 times by weight based on the benzofuran-styryl compound. If the ratio is less than 0.2 times, there is a disadvantage that the benzofuran-styryl compound precipitates from the surface of the photoreceptor. If the ratio exceeds 20 times, the sensitivity is remarkably reduced.
[0077]
In particular, an alkaline binder polymer is required for use in a printing plate. The alkaline binder polymer is a polymer substance having an acidic group that is soluble in an alcoholic alkaline solvent containing water or a mixed system with water. Examples of the soluble acidic group include an acid anhydride group, a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group and a sulfonimide group. It is preferable that these alkaline binder polymers usually have a high acid value of 100 or more. A binder polymer having a large acid value is easily dissolved or easily lubricated in an alkaline solvent. Examples of such a binder polymer include styrene: maleic anhydride copolymer, vinyl acetate: maleic anhydride copolymer, vinyl acetate: crotonic acid copolymer, methacrylic acid: methacrylic acid ester copolymer, phenol resin and Methacrylic acid: styrene: methacrylic acid ester copolymer and the like. These resins are added to the photoconductive organic substance at the same ratio as in the case of the photoconductor of a copying machine.
[0078]
Examples of the sensitizing dye include triphenylmethane dyes such as methyl violet, crystal violet, night blue and Victoria blue, acridine dyes such as erythrosine, rhodamine B, rhodamine 3R, acridine orange and flapeosin, and methylene blue. And thiazine dyes typified by methylene green and the like; oxazine dyes typified by capri blue and Meldola blue; and other Shinan dyes, styryl dyes, pyrylium salt dyes, and thiopyrylium salt dyes.
[0079]
Further, in the photosensitive layer, as a photoconductive pigment that generates charges with extremely high efficiency by light absorption, various metal phthalocyanines, phthalocyanine pigments such as metal-free phthalocyanine and halogen-free metal phthalocyanine, perylene imide and perylene anhydride, etc. And azo pigments such as bisazo pigments and trisazo pigments, other quinacridone pigments, and anthraquinone pigments. In particular, those using a metal-free phthalocyanine pigment, a titanyl phthalocyanine pigment, a bisazo pigment containing a fluorene or a fluorenone ring, a bisazo pigment composed of an aromatic amine, or a trisazo pigment as a pigment that generates electric charge exhibit excellent sensitivity. Give a photoreceptor.
[0080]
Further, the sensitizing dye may be used as a charge generating substance. The above-mentioned dyes may be used alone, but in many cases, the charge is generated with higher efficiency by the coexistence of a pigment.
[0081]
Apart from the above-mentioned ring-enhancing agents, it may be necessary to add various chemical substances for the purpose of preventing an increase in residual potential, a decrease in charge potential and a decrease in sensitivity for repeated use. is there. Additives for these include 1-chloroanthraquinone, benzoquinone, 2,3-dichloronaphthoquinone, naphthoquinone, 4,4'-dinitrobenzophenone, 4,4'-dichlorobenzophenone, 4-nitrobenzophenone, 4-nitrobenzen Salmalondinitrile, ethyl α-cyano-β- (p-cyanophenyl) acrylate, 9-anthracenylmethylmalondinitrile, 1-cyano-1- (p-nitrophenyl) -2- (p-chloro Electron withdrawing compounds such as phenyl) ethylene and 2,7-dinitrofluorenone. In addition, an antioxidant, an anti-curl agent, a leveling agent, and the like can be added as necessary to the photoreceptor.
[0082]
The benzofuran-styryl compound according to the present invention is dissolved or dispersed in an appropriate solvent together with the various additives described above depending on the form of the photoreceptor to prepare a coating solution, and the coating solution is made of a conductive material. A photoreceptor is manufactured by applying the composition on the support 1 and drying. Examples of the solvent for the coating solution include aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, single solvents such as tetrahydrofuran, dioxane, dimethoxymethyl ether, and dimethylformamide, or two or more solvents. The above-mentioned mixed solvents are exemplified. These solvents can be used by further adding a solvent such as alcohols, acetonitrile and methyl ethyl ketone, if necessary.
[0083]
The intermediate layer 8 provided between the conductive support 1 and the photosensitive layer 4 or 14 imparts a protective function or an adhesive function, enhances coatability, and further improves charge injection from the substrate to the photosensitive layer. Suitable materials include casein, polyvinyl butyral, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin, and aluminum oxide. Examples of the polyamide include nylon 6, nylon 66, nylon 610, copolymerized nylon, and alkoxymethylated nylon.
[0084]
Hereinafter, production examples of the benzofuran-styryl compound according to the present invention and the electrophotographic photoreceptor according to the present invention will be specifically described based on examples. The present invention is not limited thereby.
[0085]
(Production example)
A benzofuran-styryl compound (Exemplary Compound No. 1) was produced.
[0086]
0.81 g (1.5 equivalents) of potassium-t-butoxide was dissolved in 5 ml of tetrahydrofuran and cooled to 0 ° C in a water bath. To this solution, a solution prepared by dissolving 1.9 g (1.3 equivalents) of diethyl α, α′-diphenylbenzylphosphonate in 5 ml of tetrahydrofuran was gradually added. Stir at 0 ° C. for about 10 minutes to produce a stable Wittig ylide. To this solution, a solution prepared by dissolving 2.0 g (1.0 equivalent) of 5-formyl-2- (4 ′ (bis (p-tolyl) amino) phenyl) benzo [b] furan in 10 ml of tetrahydrofuran was gradually added. . The water bath was removed, the reaction temperature was raised to room temperature, and stirring was continued for about 2 hours.
[0087]
The completion of the reaction was confirmed by thin-layer chromatography, and a conventional extraction treatment was performed to obtain 2.58 g of the target benzofuran-styryl compound (Exemplary Compound No. 1). The yield was 95%.
[0088]
The structure of the thus obtained benzofuran-styryl compound (Exemplified Compound No. 1) was confirmed by measuring ¹ H-NMR, usually ¹³ C-NMR and DEPT 135 ¹³ C-NMR.
[0089]
FIG. 6 is a ¹ H-NHR spectrum of a benzofuran-styryl compound (Exemplary Compound No. 1) in deuterated chloroform. FIG. 7 is a normal ¹³ C-NMR spectrum of a benzofuran-styryl compound (Exemplary Compound No. 1) in deuterated chloroform. FIG. 8 is a ¹³ C-NMR spectrum of a benzofuran-styryl compound (Exemplary Compound No. 1) in deuterated chloroform at DEPT135. These NMR signals well support the structure of the target benzofuran-styryl compound (Exemplary Compound No. 1).
[0090]
(Examples 1 to 4, Comparative Example)
Examples 1, 2, 3 and 4 in which the benzofuran-styryl compounds represented by Exemplified Compound Nos. 1, 5, 14 and 21 are contained as the charge transfer substance 3 in the charge transfer layer 6 shown in FIG. Five kinds of laminated electrophotographic photosensitive members of a comparative example containing known 4- (diethylamino) -benzaldehyde-N, N-diphenylhydrazone were produced.
[0091]
In a 1% THF (tetrahydrofuran) solution of a phenoxy resin (PKHH: manufactured by Union Carbide), a bisazo pigment represented by the following structural formula (VII) is added in the same amount by weight as the resin, and a paint conditioner (Red Devil Co., Ltd.) is added. Was dispersed together with glass beads having a diameter of 1.5 mm for about 2 hours to prepare a coating solution for a charge generation layer. The prepared coating solution for a charge generation layer was applied to a support of an aluminum-deposited polyester film (80 μm thick) by a doctor blade method and dried to form a charge generation layer. The thickness of the charge generation layer after drying was 0.2 μm.
[0092]
Embedded image

[0093]
1 g of the benzofuran-styryl compound or 4- (diethylamino) -benzaldehyde-N, N-diphenylhydrazone shown as Exemplified Compound No. 1, 4, 12, or 23, and a polyarylate resin (U-100: manufactured by Unitika) 2 g was dissolved in THF to prepare a 15% solution to prepare five types of coating solutions for the charge transfer layer. The coating solution for each charge transfer layer was applied onto the charge generation layer formed as described above using a squeezing doctor and dried to form a charge transfer layer which was a resin-bisamine compound solid solution phase having a dry film thickness of 25 μm. Each was formed, and five types of laminated electrophotographic photosensitive members of Examples 1 to 4 and Comparative Example 1 were produced.
[0094]
The electrophotographic characteristics of the laminated electrophotographic photosensitive member prepared as described above were evaluated using an electrostatic recording paper test apparatus (SP-428: manufactured by Kawaguchi Electric Co., Ltd.). Applied voltage: -6 kV and static: No. Under the measurement conditions of 3, an exposure amount E100 (lux · sec) and an initial potential V0 (−volt) required for attenuating from −700 V to −100 V by white light irradiation (irradiation light: 5 lux) were measured. Further, using the above-mentioned electrostatic recording paper test apparatus, the same operation was performed 10,000 times as one cycle of charge-discharge (discharge light: irradiation of 40 lux white light for 1 second), and exposure amount E100 (lux · sec) ) And the initial potential V0 (−volt) were measured. Table 4 shows the measurement results of E100 and V0 at the first and 10,000 times.
[0095]
[Table 4]

[0096]
From Table 4, it was found that Examples 1 to 4 using the benzofuran-styryl compound according to the present invention were excellent not only in sensitivity but also in repetition characteristics as compared with Comparative Example 1 using a conventional compound.
[0097]
(Example 5)
In the charge transfer layer 6 shown in FIG. The laminated electrophotographic photoreceptor of Example 5 containing the benzofuran-styryl compound shown in No. 3 was produced.
[0098]
0.4 g of an x-type metal-free phthalocyanine (Fastgen Blue 8120: manufactured by Dainippon Ink) represented by the following structural formula (VIII) was added to a vinyl chloride: vinyl acetate copolymer resin (ESLEX M: manufactured by Sekisui Chemical Co., Ltd.) 0.3 g was dissolved in 30 ml of an ethyl acetate solution and dispersed in a paint conditioner for about 20 minutes to prepare a coating solution for a charge generation layer. The prepared coating solution for the charge generation layer is applied on a support of an aluminum-deposited polyester film by a doctor blade method and dried, and charge generation is performed so that the thickness of the charge generation layer after drying becomes 0.4 μm. A layer was formed.
[0099]
Embedded image

[0100]
On this charge generation layer, Exemplified Compound No. The laminated electrophotographic photoreceptor of Example 5 consisting of two layers was prepared by laminating a charge transfer layer of a polyarylate layer containing the benzofuran-styryl compound at a weight ratio of 50%.
[0101]
The energy (E50) required for halving the potential and the initial potential (-V0) were obtained using the light of 780 nm of the photoconductor of Example 5, and V0 = -690 (volts) and E50 = 0.21 (μJ). The photosensitive member was very sensitive and highly charged.
[0102]
Further, a laser printer (WD-580P: manufactured by Sharp Corporation) was remodeled, the photosensitive member of Example 5 was stuck to the drum portion, and continuous blank copy (Non Copy Aging) was performed 10,000 times, and then the initial potential was lowered. And the degree of sensitivity reduction was examined. As a result, at V0 = -680 (volts) and E50 = 0.22 (μJ), there was almost no change in the values compared to the first time.
[0103]
(Examples 6 to 9)
As the charge transfer material 3 shown in FIG. Four types of electrophotographic photoreceptors having a single photosensitive layer 14 containing a benzofuran-styryl compound shown in 6, 8, 13 or 24 were produced.
[0104]
1 g of Exemplified Compound No. 6, 8, 13 or 24, 1.1 g of a polycarbonate resin represented by the following structural formula (IX), N, N-3,5-xylyl-3,4,9,10-perylenetetracarboximide 0 .15 g and 0.05 g of an ultraviolet absorber were dissolved in 14.0 ml of methylene chloride to prepare a coating solution for a photosensitive layer. The imide compound was partially dispersed in the photosensitive layer coating solution. The prepared coating solution for a photosensitive layer is applied to a support having an alumite-processed aluminum plate surface (alumite layer: 7 μm) by an applicator and dried, and a single-layer photosensitive member having a dried photosensitive layer thickness of 20 μm is obtained. Was.
[0105]
Embedded image

[0106]
The electrophotographic characteristics of the single-layer type electrophotographic photosensitive member produced as described above were evaluated by the electrostatic recording paper test apparatus. Applied voltage: 5.5 kV and static: No. Under the measurement conditions of 3, an exposure amount E100 (lux · sec) required to attenuate from +700 V to +100 V by white light irradiation (irradiation light: 5 lux) was measured. In addition, 10,000 continuous blank copies were performed, and the degree of decrease in sensitivity (E100) was examined. Table 5 shows the measurement results of E100 at the first time and at the 10,000th time.
[0107]
[Table 5]

[0108]
Table 5 shows that the photoconductors of Examples 6 to 9 using the benzofuran-styryl compound according to the present invention have excellent sensitivity and repetition characteristics even in positive charging.
[0109]
【The invention's effect】
As described above, according to the present invention, an electrophotographic photoreceptor having high sensitivity and high durability by having a wide conjugated system, being excellent in compatibility with a binder polymer, and having a feature of being hardly precipitated as a crystal. , A novel benzofuran-styryl compound having a benzofuran skeleton.
[0110]
Further, according to the present invention, a benzo [b] furanaldehyde compound is reacted with a phosphorus reagent to produce a benzofuran-styryl compound, which is excellent as a charge transfer material for an electrophotographic photoreceptor, very easily and in high yield. A method can be provided.
[0111]
Therefore, according to the present invention, by containing the benzofuran-styryl compound as a charge transfer material, it has high sensitivity and high durability in an organic system, is nontoxic and has no problem in resources as compared with an inorganic system, Provide an electrophotographic photoreceptor having excellent characteristics such as high transparency, light weight, excellent film-forming properties, easy charging and positive / negative chargeability, and little reduction in photosensitivity even when used repeatedly. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating an example of an electrophotographic photosensitive member having a function-separated type photosensitive layer having a charge transfer layer 6 on a charge generation layer 5.
FIG. 2 is a function-separated type photosensitive layer having a charge generation layer 5 on a charge transfer layer 6;
FIG. 3 is a cross-sectional view schematically illustrating an example of an electrophotographic photosensitive member having a dispersion type photosensitive layer.
FIG. 4 is a cross-sectional view showing an example having a surface protective layer 7 in the electrophotographic photoreceptor of FIG.
5 is a cross-sectional view showing an example having an intermediate layer 8 in the electrophotographic photoreceptor of FIG.
FIG. 6 is a ¹ H-NHR spectrum of a benzofuran-styryl compound (exemplary compound No. 1) in deuterated chloroform.
FIG. 7 is a normal ¹³ C-NMR spectrum of a benzofuran-styryl compound (exemplified compound No. 1) in deuterated chloroform.
FIG. 8 is a ¹³ C-NMR spectrum of a benzofuran-styryl compound (Exemplary Compound No. 1) in deuterated chloroform at DEPT135.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 conductive support 2 charge generation material 3 charge transfer material 4, 14 photosensitive layer 5 charge generation layer 6 charge transfer 7 surface protection layer 8 intermediate layer

Claims (8)

An electrophotographic photoreceptor comprising a benzofuran-styryl compound represented by the following general formula (I) as a charge transfer material in a photosensitive layer provided on a conductive support.

(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.) The electrophotographic photoreceptor according to claim 1, wherein the benzofuran-styryl compound is a compound represented by the following general formula (II).

(In the formula, b is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and m represents an integer of 1 to 4. However, when m is 2 or more, B may be the same or different. Ar ₂ , Ar ₃ , Ar ₄ , a and n have the same meanings as those shown in formula (I).) 2. The electrophotographic photoreceptor according to claim 1, wherein the benzofuran-styryl compound is a compound represented by the following general formula (III).

(In the formula, d is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and 1 to 5 carbon atoms which may have a substituent. Represents a fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and l represents an integer of 1 to 5. However, when l is 2 or more, May be the same or different. Ar ₃ , Ar ₄ , a, b, n, and m have the same meanings as those shown in formula (II).) The electrophotographic photoreceptor according to claim 1, wherein the benzofuran-styryl compound is a compound represented by the following general formula (IV).

(Wherein, e is an alkyl group having 1 to 5 carbon atoms which may have a substituent, a fluoroalkyl group having 1 to 5 carbon atoms which may have a substituent, and a peralkyl group having 1 to 5 carbon atoms which may have a substituent. A fluoroalkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and k represents an integer of 1 to 5. However, when k is 2 or more, May be the same or different. Ar ₃ , Ar ₄ , a, b, n, and m have the same meanings as those shown in formula (III).) 5. The photosensitive layer according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer containing a charge generation material and a charge transfer layer containing the charge transfer material. Electrophotographic photoreceptor. The electrophotographic photoconductor according to any one of claims 1 to 4, wherein the photosensitive layer comprises a single layer containing a charge generating substance and the charge transfer substance. A benzofuran-styryl compound represented by the following general formula (I).

(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.) A benzo [b] furanaldehyde compound represented by the following general formula (V) is reacted with a phosphorus reagent represented by the following general formula (VI) to produce a benzofuran-styryl compound represented by the following general formula (I) A method for producing a benzofuran-styryl compound.

(Wherein, Ar ₁ represents an arylene group which may have a substituent or a divalent heterocyclic group which may have a substituent. Ar ₂ may have an aryl group which may have a substituent or a substituent. Ar ₃ and Ar ₄ each represent a heterocyclic group or an aralkyl group which may have a substituent, and Ar ₃ and Ar ₄ each represent an aryl group which may have a substituent, a heterocyclic group which may have a substituent, and an aralkyl which may have a substituent. A represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom which may contain a substituent, and a represents an alkyl group having 1 to 5 carbon atoms which may contain a substituent or 1 to 5 carbon atoms which may contain a substituent. A fluoroalkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms which may contain a substituent, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, and n Is 1 And an integer of from 4 to 4. However, when n is 2 or more, a plurality of a may be the same or different, and may form a ring with each other.)

(In the formula (V), Ar ₁ , Ar ₂ , a and n have the same meanings as those shown in the general formula (I).

(In the formula (VI), Ar ₃ and Ar ₄ have the same meanings as those shown in the general formula (I). Ar ₅ is an aryl group optionally having a substituent, an aralkyl group optionally having a substituent or It shows a C1-C3 alkyl group which may contain a substituent.

Images