JP2004212889A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor free from causing image defects due to uprush of residual potential, such as lowering of density, and free of filming due to adhesion of paper powder, toner, etc., to a photoreceptor surface accompanied by the image defects even under high potential and high exposure. <P>SOLUTION: In the electrophotographic photoreceptor discharged by contact with a charging member, a layer brought into contact with the charging member contains 100 pts. wt. binder resin and 0.025 to 1.5 pts. wt. of a polysiloxane compound as essential components independently of the function of the layer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３２】
〔式中、Ｒ^１およびＲ^２は同一または異なって、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良いアリール基または置換基を有していても良いアラルキル基を示す。〕
で表される構造単位を有するポリシロキサン化合物などが挙げられる。
【００３３】
上記一般式（１）において、Ｒ^１およびＲ^２で示されるアルキル基としては、たとえば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、ヘキシル基、へプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、エイコシル基などの、炭素数１〜２０の直鎖または分岐鎖状のアルキル基が挙げられる。これらの中でも、炭素数１〜４の直鎖または分岐鎖状のアルキル基が好ましい。アリール基としては、たとえば、フェニル基、トリル基、キシリル基、ビフェニリル基、ナフチル基などが挙げられる。これらの中でも、フェニル基が好ましい。アラルキル基としては、たとえば、２−フェニルエチル、ベンジル、１−フェニルエチル、３−フェニルプロピル、４−フェニルブチルなどが挙げられる。アルキル基、アリール基およびアラルキル基のなかでも、アルキル基が好ましい。
【００３４】
また、Ｒ^１およびＲ^２で示されるアルキル基、アリール基およびアラルキル基の置換基としては、たとえば、ハロゲン原子、アルコキシ基、アルキルチオ基、アリールオキシ基、アリールチオ基、アルコキシカルボニル基、アシル基、アシロキシ基、メルカプト基、シアノ基などが挙げられる。
【００３５】
上記一般式（１）で表される構造単位を含むポリシロキサン化合物は、１種の構造単位からなるものであってもよいし、たとえば、ジアルキル体とアルキルアルコキシアルキル体が混在したポリシロキサン化合物などのように、２種以上の異なる構造単位からなるものであってもよい。
【００３６】
これらの中でも、ジメチルポリシロキサン、メチルフェニルポリシロキサンなどが好ましく、ジメチルポリシロキサンが特に好ましい。
【００３７】
本発明においては、市販のポリシロキサン化合物を使用することもできる。その具体例としては、たとえば、ＳＨ２００（商品名、東レシリコーン（株）製）、ＫＦ５４、ＫＦ９６（いずれも商品名、信越シリコーン（株）製）などが挙げられる。
【００３８】
ポリシロキサン化合物の分子量は、特に制限はされないけれども、通常は１０００〜７００００、好ましくは１５００〜３００００である。分子量が１０００よりも著しく小さいと、ポリシロキサン化合物のレベリング剤としての効果（ユズ肌防止効果など）が低下する傾向にある。また、７００００よりも著しく大きいと、バインダ樹脂との相溶性が低下し、フィルミング防止効果が充分に発揮されない傾向にある。
【００３９】
ポリシロキサン化合物は１種を単独で使用できまたは２種以上を併用できる。
ポリシロキサン化合物の含有量は、バインダ樹脂１００重量部に対して０．０２５〜１．５重量部、好ましくは０．０３〜１．５重量部である。０．０２５重量部未満では、フィルミングの防止が不充分になり、画像不良を引き起こす。また、１．５重量部を超えると、帯電部材と接触する層を構成するバインダ樹脂および後述するその他の成分との相溶性が低下し塗布不良が発生して、画像不良が発生することがある。また、帯電部材と接触する層が不均一になるため、実使用に耐えない。
【００４０】
〔導電性支持体〕
導電性支持体２としては公知のものを使用でき、たとえば、アルミニウム、ステンレス鋼、銅、ニッケルなどの金属からなるもの、樹脂フィルム（たとえばポリエステルフィルム）、紙、セラミックス（たとえばガラス）などの絶縁性基体の表面にアルミニウム、銅、パラジウム、酸化錫、酸化インジウムなどの金属または導電性金属酸化物からなる導電層を形成したもの、前記と同様の絶縁性基体の表面に導電性粉末とバインダ樹脂とを含む導電性樹脂組成物からなる導電層を形成したものなどが挙げられる。これらの中でも、金属のエンドレスパイプを適当な長さに切断したものが好ましく、アルミニウムが特に好ましい。導電性支持体の表面には、画質に影響のない範囲で、たとえば、酸化処理、薬品処理などの各種処理を施すことができる。
【００４１】
〔電荷発生層〕
電荷発生層３は、電荷発生物質およびバインダ樹脂を含有する。
【００４２】
電荷発生物質としては公知のものを使用でき、たとえば、セレンおよびその合金、砒素−セレン、硫化カドミウム、セレン化カドミウム、酸化亜鉛などの無機系電荷発生物質、フタロシアニン類（銅、錫、亜鉛、バナジウム、オキシチタニウム、塩化インジウムなどの金属、酸化物または塩化物が配位した金属フタロシアニン、無金属フタロシアニンなど）、アゾ顔料（モノアゾ、ビスアゾ、トリスアゾ、ポリアゾ類など）、キナクリドン、多環キノン、ピリリウム塩、インジゴ、チオインジゴ、アントアントロン、ピラントロン、シアニンなどの有機系電荷発生物質などが挙げられる。これらの中でも、有機系電荷発生物質が好ましく、フタロシアニン類、アゾ顔料などが特に好ましい。なお、本発明の電子写真感光体を５３０〜８５０ｎｍの範囲のレーザ光による露光装置を備える画像形成装置に使用する場合には、感度の点から、α型、β型、Ｙ型、アモルファス型、無定形などのオキシチタニウムフタロシアニンが好ましく、それらの混晶やブレンドでもかまわない。電荷発生物質は１種を単独で使用できまたは２種以上を併用できる。
【００４３】
バインダ樹脂としては公知のものを使用でき、たとえば、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、ビニルアルコール、エチルビニルエーテルなどのビニル化合物の単独重合体、同族重合体および共重合体、ポリビニルアセタール、ポリカーボネート、ポリエステル、ポリアミド、ポリウレタン、セルロースエーテル、ブチラール樹脂、フェノキシ樹脂、ケイ素樹脂、エポキシ樹脂などが挙げられる。バインダ樹脂は、１種を単独で使用できまたは必要に応じて２種以上を混合して使用できる。バインダ樹脂の使用量は特に制限されず、広い範囲から適宜選択できるけれども、通常は電荷発生物質１００重量部に対して樹脂固形分量で２５〜５００重量部、好ましくは６０〜２５０重量部である。
【００４４】
電荷発生層３が電荷輸送物質を含む電荷発生層３ａである場合、電荷輸送物質としては、後述の電荷輸送層４の項目で挙げる電荷輸送物質から選ばれる１種または２種以上を使用できる。電荷輸送物質の含有量は特に制限されず、広い範囲から適宜選択できるけれども、通常は電荷発生物質１重量部に対して１０〜２００重量部、好ましくは２０〜８０重量部である。このとき、バインダ樹脂は、電荷発生物質と電荷輸送物質との合計量１００重量部に対し、通常は１００〜１０００重量部、好ましくは２００〜３００重量部使用する。
【００４５】
電荷発生層３が導電性支持体２に対して最外層である場合は、電荷発生層３はバインダ樹脂および電荷発生物質とともにポリシロキサン化合物を含有する。ポリシロキサン化合物の含有量は、前述のとおり、バインダ樹脂の固形分１００重量部に対して０．００２５〜１．５重量部、好ましくは０．０３〜１．５重量部である。
【００４６】
さらに、電荷発生層３は、成膜性、可撓性、塗布性、機械的強度、その他の性能を向上させるために、たとえば、可塑剤、酸化防止剤、紫外線吸収剤、レベリング剤、カール防止剤などの、従来から電荷発生層に添加されている添加剤の１種または２種以上を含んでいてもよい。
【００４７】
電荷発生層３は、バインダ樹脂および電荷発生物質ならびに必要に応じて電荷輸送物質、ポリシロキサン化合物を適当な溶剤に溶解または分散して塗布液を調製し、この塗布液を導電性支持体または他の層が設けられた導電性支持体に塗布し、乾燥することによって形成される。溶剤としては前記各成分を溶解または分散できるものを使用でき、たとえば、ベンゼン、トルエン、キシレン、モノクロルベンゼンなどの芳香族炭化水素類、ジオキサン、１，３−ジオキソラン、ジメトキシメチルエーテルなどのエーテル類、ジメチルホルムアミドなどのアミド類、メタノール、エタノール、プロパノール、ブタノールなどの低級アルコール類、アセトニトリルなどのニトリル類、メチルエチルケトンなどのケトン類、テトラヒドロフランなどを挙げることができる。溶剤は１種を単独で使用できまたは必要に応じて２種以上を混合して使用できる。溶剤の使用量は特に制限されず、各成分の使用量に応じ、各成分を溶解または分散できかつ導電性支持体への塗布が円滑に進む量を適宜選択すればよい。塗布方法としては公知の方法を採用でき、たとえば、ロールコーティング、バーコーティング、ディップコーティング、スプレーコーティング、ブレードコーティング、リングコーティングなどの方法が挙げられる。塗布液の塗布量は特に制限されない。しかしながら、通常は乾燥後の膜厚が０．０５〜５μｍ、好ましくは０．１〜１μｍになるように塗布液を塗布する。乾燥は自然乾燥を行ってもよいし、または加熱乾燥を行ってもよい。加熱乾燥は、通常４０〜１２０℃程度の温度下に行われ、１０分〜１時間程度で終了する。
【００４８】
電荷発生層３は、電荷発生物質を成膜してなる層であってもよい。電荷発生物質の成膜は、たとえば、真空蒸着、イオンプレーティング、化学蒸着などの蒸着法、スパッタリング法などの公知の方法によって行われる。電荷発生物質の成膜層に電荷輸送物質を含有させるには、バインダ樹脂および電荷輸送物質を溶剤に溶解または分散させ、これを該成膜層に含浸させ、乾燥すればよい。電荷発生物質の成膜層にポリシロキサン化合物を含有させるには、バインダ樹脂およびポリシロキサン化合物を溶剤に溶解または分散させ、これを該成膜層に含浸させ、乾燥すればよい。いずれの場合にも、バインダ樹脂および溶剤としては、上記と同様のものを使用できる。
【００４９】
〔電荷輸送層〕
電荷輸送層４は、電荷輸送物質およびバインダ樹脂を含む。
【００５０】
電荷輸送物質としては公知のものを使用でき、たとえば、ポリビニル−Ｎ−ビニルカルバゾールおよびその誘導体、ポリカルバゾリルエチルグルタメートおよびその誘導体、ピレン−ホルムアルデヒド縮合物およびその誘導体、ポリビニルピレン、ポリビニルフェナントレン、オキサゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、９−（ｐ−ジエチルアミノスチリル）アントラセン、１，１−ビス（４−ジベンジルアミノフェニル）プロパン、スチリルアントラセン、スチリルピラゾリン、ピラゾリン誘導体、フェニルヒドラゾン類、ヒドラゾン誘導体、トリフェニルアミン系化合物、テトラフェニルジアミン系化合物、トリフェニルメタン系化合物、スチルベン系化合物、３−メチル−２−ベンゾチアゾリン環を有するアジン化合物などの電子供与性電荷輸送物質、フルオレノン誘導体、ジベンゾチオフェン誘導体、インデノチオフェン誘導体、フェナンスレンキノン誘導体、インデノピリジン誘導体、チオキサントン誘導体、ベンゾ［ｃ］シンノリン誘導体、フェナジンオキサイド誘導体、テトラシアノエチレン、テトラシアノキノジメタン、プロマニル、クロラニル、ベンゾキノン、ブタジエン系化合物、スチリル系化合物、アミン化合物などの電子受容性電荷輸送物質などが挙げられる。これらのなかでも、ホール輸送能力が高く、バインダ樹脂の比率が高い状態でも高感度を維持できるという観点から、ブタジエン系化合物、スチリル系化合物、アミン化合物などが好ましい。ブタジエン化合物の具体例としては、たとえば、一般式
【００５１】
【化２】

【００５２】
〔式中、Ａｒ_１、Ａｒ_２、Ａｒ_３およびＡｒ_４はそれぞれ置換基を有してもよいアリール基を示し、Ａｒ_１〜Ａｒ_４の少なくとも１つは置換基として置換アミノ基を有するアリール基である。ｎは０または１を示す。〕
で表されるブタジエン系化合物などが挙げられる。スチリル化合物の具体例としては、たとえば、一般式
【００５３】
【化３】

【００５４】
〔式中、Ａｒ_５は置換基を有しても良いアリール基を示す。Ａｒ_６は置換基を有しても良いフェニレン基、ナフチレン基、ビフェニレン基またはアントリレン基を示す。Ｒ_１７は水素原子、低級アルキル基または低級アルコキシ基を示す。Ｘは水素原子、置換基を有しても良いアルキル基または置換基を有しても良いアリール基を示す。Ｙは置換基を有しても良いアリール基などを示す。〕
で表されるスチリル化合物などが挙げられる。アミン化合物としては、たとえば、一般式
【００５５】
【化４】

【００５６】
〔式中、Ｒ_１８〜Ｒ_２３は水素原子、ハロゲン原子、アルキル基またはアルコキシ基を示す。ｐ、ｑ、ｔおよびｕはそれぞれ１〜５の整数を示す。ｒおよびｓは１〜４の整数を示す。〕
で表されるアミン化合物などが挙げられる。電荷輸送物質は１種を単独で使用できまたは２種以上を併用できる。
【００５７】
バインダ樹脂としては、電荷輸送物質と相溶性が良く、電荷輸送層４の形成後に電荷輸送物質が結晶化したり、相分離することのないものが好ましい。その具体例としては、たとえば、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、ビニルアルコール、エチルビニルエーテルなどのビニル化合物の単独重合体、同族重合体および共重合体、ポリビニルアセタール、ポリカーボネート、ポリエステル、ポリスルホン、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、ケイ素樹脂、エポキシ樹脂などが挙げられる。これらのなかでも、機械的強度が高くかつポリシロキサン化合物と少なくとも一部が相溶するものが好ましく、この点から、ポリカーボネート、ポリアリレート、これらの混合物などが好ましい。バインダ樹脂は１種を単独で使用できまたは必要に応じて２種以上を併用できる。バインダ樹脂の含有量は特に制限されず、広い範囲から適宜選択できるけれども、通常は電荷輸送物質１００重量部に対して固形分で６０〜３００重量部、好ましくは１４０〜２５０重量部である。
【００５８】
電荷輸送層４が導電性支持体２に対して最外層である場合は、電荷輸送層４は電荷輸送物質およびバインダ樹脂とともにポリシロキサン化合物を含んでいる。ポリシロキサン化合物の含有量は、前述のように、バインダ樹脂の固形分１００重量部に対して０．０２５〜１．５重量部、好ましくは０．０３〜１．５重量部である。
【００５９】
電荷輸送層４は、バインダ樹脂および電荷輸送物質のほかに、電子受容性化合物、酸化防止剤などを含んでいてもよい。電子受容性化合物は電子受容性電荷輸送物質以外のものであり、たとえば、テトラシアノキノジメタン、ジシアノキノメタン、ジシアノキノビニル基を有する芳香族エステル類のシアノ化合物、２，４，６−トリニトロフルオレノンなどのニトロ化合物、ペリレンなどの縮合多環芳香族化合物、ジフェノキノン誘導体、キノン類、アルデヒド類、ケトン類、エステル類、酸無水物、フタリド類、置換および無置換サリチル酸の金属錯体、置換および無置換サリチル酸の金属塩、芳香族カルボン酸の金属錯体、芳香族カルボン酸の金属塩などが挙げられる。これらの中でも、シアノ化合物、縮合多環芳香族化合物、ジフェノキノン誘導体、置換および無置換サリチル酸の金属錯体、置換および無置換の金属塩、芳香族カルボン酸の金属錯体、芳香族カルボン酸の金属塩などが好ましい。電子受容性化合物は１種を単独で使用できまたは２種以上を併用できる。酸化防止剤としては、樹脂などに添加される公知の酸化防止剤を使用でき、たとえば、ビタミンＥ、ハイドロキノン、ヒンダードアミン、ヒンダードフェノール、パラフェニレンジアミン、アリールアルカンおよびそれらの誘導体、有機硫黄化合物、有機リン化合物などが挙げられる。酸化防止剤は１種を単独で使用できまたは２種以上を併用できる。
【００６０】
さらに、電荷輸送層４は、成膜性、可撓性、塗布性、機械的強度、その他の性能を向上させるために、可塑剤、酸化防止剤、紫外線吸収剤、顔料、レベリング剤、カール防止剤、増感剤などの、従来から電荷輸送層に添加されている添加剤の１種または２種以上を含んでいてもよい。
【００６１】
電荷輸送層４は、電荷輸送物質およびバインダ樹脂ならびに必要に応じて電子受容性化合物、酸化防止剤、その他の添加剤などを溶剤に溶解または分散させ、得られる塗布液を導電性支持体または他の層が設けられた導電性支持体に塗布し、乾燥させることによって形成することができる。この一連の操作は、電荷発生層３を形成する場合と同様にして実施することができる。なお、電荷輸送層４の膜厚は特に制限されないけれども、通常は１０〜５０μｍ、好ましくは１０〜３５μｍである。
【００６２】
〔ブロッキング層〕
ブロッキング層５には、たとえば、下引き層、アルマイト層などがある。
【００６３】
下引き層はバインダ樹脂を含有する。バインダ樹脂としては公知のものを使用でき、たとえば、ポリビニルメチルエーテル、ポリ−Ｎ−ビニルイミダゾール、ポリエチレンオキシド、エチルセルロース、メチルセルロース、エチレン−アクリル酸共重合体、ポリアミド、カゼイン、ゼラチン、ポリエチレン、ポリエステル、フェノール樹脂、塩化ビニル−酢酸ビニル共重合体、エポキシ樹脂、ポリビニルピロリドン、ポリビニルピリジン、ポリウレタン、ポリグルタミン酸、ポリアクリル酸、ポリアミド樹脂などが挙げられる。これらのなかでも、導電性支持体との接着性に優れ、電荷発生層の塗布液に用いられる溶剤に対する溶解性の小さいポリアミド樹脂が好ましい。バインダ樹脂は１種を単独で使用できまたは２種以上を併用できる。
【００６４】
下引き層は、主にレーザ露光における干渉縞を防ぐ目的で、アルミナ、チタニアなどの金属酸化物微粒子、レーザ光を吸収することができる有機または無機の色素を含んでいてもよい。金属酸化物微粒子の形状は特に制限されず、たとえば、針状（繊維状）、薄片状（鱗片状）、粒子状などが挙げられる。金属酸化物微粒子および／または色素の含有量は特に制限されず、広い範囲から適宜選択できる。しかしながら、バインダ樹脂、金属酸化物微粒子および／または色素ならびに溶剤からなる下引き層形成用の塗布液の保存安定性、導電性支持体への塗布性など考慮すると、通常はバインダ樹脂固形分１００重量部に対して４０〜４００重量部の金属酸化物微粒子および／または色素を使用する。
【００６５】
下引き層は、バインダ樹脂および必要に応じて金属酸化物微粒子、色素、その他の添加剤（可塑剤、酸化防止剤、紫外線吸収剤、レベリング剤、カール防止剤など）などを溶剤に溶解または分散させ、得られる塗布液を導電性支持体に塗布し、乾燥させることによって形成することができる。この一連の操作は、電荷発生層を形成する場合と同様にして実施することができる。なお、下引き層の膜厚は特に制限されないけれども、通常は０．１〜１０μｍ、好ましくは０．２〜５μｍである。
【００６６】
アルマイト層は、導電性支持体を陽極酸化することによって形成できる。陽極酸化は公知の方法に従って実施できる。たとえば、アルミニウムまたはアルミニウム合金からなる導電性支持体に必要に応じて脱脂処理を施した後、この導電性支持体を陽極とし、酸性浴中で電解を行えばよい。酸性浴としては、たとえば、クロム酸、硫酸、シュウ酸、ホウ酸、スルファミン酸などが挙げられる。電解条件は特に制限されないけれども、酸性浴の液温を１０〜３０℃程度、印加電圧を５〜１５０Ｖ程度および電流密度を０．１〜５００Ａ／ｍ^２程度とすればよい。
【００６７】
電解酸化によって形成されるアルマイト層には、封孔処理を施してもよい。
封孔処理は公知の方法に従って実施することができ、酸化ニッケルを主成分とする水溶液、フッ化ニッケルを主成分とする水溶液、重クロム酸塩水溶液、ケイ酸ナトリウム水溶液などに浸漬する処理、水蒸気処理、沸騰水処理、樹脂を含浸させる処理などを挙げることができる。
【００６８】
アルマイト層の膜厚は特に制限されないけれども、通常は１〜２０μｍ、好ましくは３〜１５μｍである。
【００６９】
〔感光層〕
感光層６は、電荷発生層３、電荷輸送物質を含有する電荷発生層３ａおよび電荷輸送層４から選ばれる１種または２種以上の層を含んで構成される。電荷発生層３、電荷輸送物質を含有する電荷発生層３ａおよび電荷輸送層４は、上記のとおりである。
【００７０】
感光層６が導電性支持体２に対して最外層である場合には、感光層６を構成する層のうちの、導電性支持体２に対して最も外の層中に、バインダ樹脂１００重量部に対して０．０２５〜１．５重量部、好ましくは０．０３〜１．５重量部のポリシロキサン化合物が含まれている。
【００７１】
〔保護層〕
保護層７は、バインダ樹脂を含んでいる。さらに、保護層７は、本発明の電子写真感光体おいて、導電性支持体２に対しての最外層に設けられるので、ポリシロキサン化合物を含んでいる。
【００７２】
バインダ樹脂としては電気的に不活性なものを使用でき、たとえば、ＡＢＳ樹脂、ＡＣＳ樹脂、オレフィン−ビニルモノマー共重合体、塩素化ポリエーテル、アクリル樹脂、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアクリレート、ポリアリルスルホン、ポリブチレン、ポリブチレンテレフタレート、ポリイミド、アクリル樹脂、ポリメチルペンテン、ポリプロピレン、ポリフェニレンオキシド、ポリスルホン、ポリスチレン、ＡＳ樹脂、ブタジエン−スチレン共重合体、ポリウレタン、ポリ塩化ビニル、エポキシ樹脂などが挙げられる。また、これらのバインダ樹脂のうち、硬化剤によって硬化可能なものは、硬化剤を含んでいてもよい。バインダ樹脂は１種を単独で使用できまたは２種以上を混合して使用できる。
【００７３】
ポリシロキサン化合物の含有量は、前述のとおり、バインダ樹脂の固形分１００重量部に対して０．０２５〜１．５重量部、好ましくは０．３〜１．５重量部である。
【００７４】
保護層７は、高分子電荷輸送物質を含んでいてもよい。高分子電荷輸送物質としては、前述の電荷輸送物質に例示されており、たとえば、ポリビニル−Ｎ−ビニルカルバゾールおよびその誘導体、ポリカルバゾリルエチルグルタメートおよびその誘導体、ピレン−ホルムアルデヒド縮合物およびその誘導体、ポリビニルピレン、ポリビニルフェナントレンなどが挙げられる。高分子電荷輸送物質は１種を単独で使用できまたは２種以上を併用できる。
【００７５】
保護層７は、その耐摩耗性を向上させる目的で、充填材を含んでいてもよい。充填材としては公知のものを使用でき、たとえば、ポリテトラフルオロエチレンなどのフッ素樹脂粉末、シリコーン樹脂粉末、ａ−カーボン粉末などの有機充填材、銅、スズ、アルミニウム、インジウムなどの金属粉末、酸化錫、酸化亜鉛、酸化チタン、酸化インジウム、酸化アンチモン、酸化ビスマス、アンチモンをドープした酸化錫、錫をドープした酸化インジウムなどの金属酸化物、チタン酸カリウム、ワラストナイト、タルクなどの繊維状、薄片状または粉末状の無機材料などの無機充填材が挙げられる。充填材は１種を単独で使用できまたは２種以上を併用できる。充填材の平均粒径は特に制限されず、広い範囲から適宜選択できるけれども、保護層の透過率を考慮すると、通常は０．５μｍ以下、好ましくは０．２μｍ以下である。
【００７６】
保護層７は、バインダ樹脂およびポリシロキサン化合物ならびに必要に応じて高分子電荷輸送物質、充填材、その他の添加剤（可塑剤、酸化防止剤、紫外線吸収剤、レベリング剤、カール防止剤など）などを溶剤に溶解または分散させ、得られる塗布液を他の層が形成されている導電性支持体に塗布し、乾燥させることによって形成することができる。この一連の操作は、溶剤としてたとえば、テトラヒドロフラン、ジオキサン、トルエン、モノクロルベンゼン、ジクロルエタン、塩化メチレン、シクロヘキサノンなどを使用する以外は、電荷発生層を形成する場合と同様にして実施することができる。なお、保護層７の膜厚は特に制限されないけれども、通常は０．０１〜１００μｍ、好ましくは１〜１０μｍである。
【００７７】
なお、電荷発生層３、電荷輸送物質を含む電荷発生層３ａ、電荷輸送層４または保護層７にポリシロキサン化合物を含有させるには、上記で示した、バインダ樹脂およびその他成分とともにポリシロキサン化合物を溶剤に溶解または分散させて塗布液とし、これを塗布して各層を形成する方法以外に、ポリシロキサン化合物を含まない各層を形成しておき、これにポリシロキサン化合物またはその溶液を含浸させる方法もある。
【００７８】
このように各層を形成して得られる本発明の電子写真感光体は、複写機、レーザプリンタ、レーザファクシミリなどの電子写真方式の画像形成装置の中でも、接触帯電方式を採用している画像形成装置の電子写真感光体として好適に使用できる。
【００７９】
つぎに、図面を参照しつつ、本発明の画像形成装置について説明する。図８は、本発明の実施の形態である画像形成装置の電子写真部の概略を示す構成図である。画像形成装置１０の電子写真部１１は、電子写真感光体１２、電子写真感光体１２を所定の電位に帯電するための接触式帯電器１３、電子写真感光体１２の表面に静電潜像を形成するための露光装置１４、該静電潜像を現像して可視像を形成するための現像器１５、該可視像を記録媒体に転写するための転写帯電器１６、該可視像を記録媒体に定着させるための定着器１７および電子写真感光体１２の表面を清浄化するためのクリーナ１８を含んで構成されている。
【００８０】
電子写真感光体１２の周囲に、接触式帯電器１３、露光装置１４、現像器１５、転写帯電器１６、定着器１７およびクリーナ１８が順に配置されている。接触式帯電器１３は、帯電ドラムなどを用いた接触帯電手段である。
【００８１】
ドラム状の電子写真感光体１２は、図示しない駆動手段によって矢符１９の方向に所定の周速度で回転駆動される。感光体１２は、回転過程において、接触式帯電器１３によってその周面に正または負の所定電位の均一帯電を受ける。次いで、露光装置１４からの光が、感光体１２の表面に対してその長手方向（主走査方向）に繰返し走査され、感光体１２の周面に静電潜像が順次形成されていく。形成された静電潜像は、結像点よりも回転方向下流に設けられた現像器１５により、トナー像として現像される。
【００８２】
感光体１２への露光と同期して、記録媒体である記録紙が現像器１５のさらに回転方向下流側に設けられる転写帯電器１６に与えられ、記録紙にトナー像が転写される。記録紙は定着器１７に搬送されて、トナー像が記録紙に定着される。このようにして画像が形成された記録紙は排紙される。クリーナ１８は、転写帯電器１６のさらに回転方向下流側であって接触式帯電器１３の回転方向上流側に、図示しない除電ランプとともに設けられ、感光体１２表面に残留するトナーを清掃する。また、接触帯電器１３に感光体１２上の残留トナーをクリーニングする機能を持たせ、クリーニング１８を省いてもよいし、さらに光除電プロセスも省くことができる。
【００８３】
感光体１２を回転させることによって以上の回転過程が繰返され、画像が形成される。
【００８４】
なお、接触式帯電器１３により感光体１２の周面を負帯電させる場合、露光により表面電荷が減少した露光領域にマイナス帯電されたトナーを付着させて現像する反転現像プロセスが採用される。
【００８５】
さらに、感光体１２を、接触式帯電器１３、現像器１５およびクリーナ１８のうちの少なくとも１つと一体的に構成して、プロセスカートリッジとしてもかまわない。たとえば、感光体１２、接触式帯電器１３、現像器１５およびクリーナ１８のすべてを組込んだプロセスカートリッジ、感光体１２、接触式帯電器１３および現像器１５を組込んだプロセスカートリッジ、感光体１２とクリーナ１８とを組込んだプロセスカートリッジおよび感光体１２と現像器１５とを組込んだプロセスカートリッジが構成可能である。このようなプロセスカートリッジを用いると、プリンタなどにおける交換が容易となる。
【００８６】
図９は、本発明の他の実施の形態である画像形成装置１０の構成を示す断面図である。画像形成装置１０は、大略スキャナ部２０と、記録部２１とを含んで構成される。スキャナ部２０は、透明ガラスからなる原稿載置台２２と、原稿載置台２２上へ自動的に原稿を供給搬送るための自動原稿送り装置２３と、原稿載置台２２上に載置された原稿の画像を走査して読取るための原稿画像読取りユニットであるスキャナユニット２４とを含む。このスキャナ部２０にて読取られた原稿画像は、画像データとして、後述する画像データ入力部へと送られ、画像データに対して所定の画像処理が施される。自動原稿送り装置２３には、自動原稿送り装置２３に備わる図示しない原稿トレイ上に複数枚の原稿を一度にセットしておき、セットされた原稿を１枚ずつ自動的に原稿載置台２２上へ供給する装置である。また自動原稿送り装置２３は、オペレータの選択に応じて原稿の片面または両面をスキャナユニット２４に読取らせるように、片面原稿のための搬送経路、両面原稿のための搬送経路、搬送経路切り換え手段、各部を通過する原稿の状態を把握し管理するセンサー群、制御部などを含んで構成される。
【００８７】
スキャナユニット２４は、原稿面上を露光するランプリフレクタアセンブリ２５と、原稿からの反射光像を光電変換素子３２に導くために原稿からの反射光を反射する第１反射ミラー２６を搭載する第１走査ユニット２７と、第１反射ミラー２６からの反射光像を光電変換素子３２に導くための第２および第３反射ミラー２８，２９を搭載する第２走査ユニットと、原稿からの反射光像を前述の各反射ミラー２６，２８，２９を介して電気的画像信号に変換する光電変換素子３２上に結像させるための光学レンズ３１と、前記光電変換素子３２とを含む構成である。
【００８８】
スキャナ部２０は、自動原稿送り装置２３とスキャナユニット２４との関連動作によって、原稿載置台２２上に読取るべき原稿を順次給送載置させるとともに、原稿載置台２２の下面に沿ってスキャナユニット２４を移動させて原稿画像を読取れるように構成される。第１走査ユニット２７は、原稿載置台２２に沿って原稿画像の読取り方向（図２では紙面に向かって左から右）に一定速度Ｖで走査され、また第２走査ユニット３０は、その速度Ｖに対して、たとえば２分の１（Ｖ／２）の速度で同一方向に平行に走査される。この第１および第２走査ユニット２７，３０の動作によって、原稿載置台２２上に載置された原稿画像を１ライン毎に順次光電変換素子３２へ結像させて画像を読取ることができる。
【００８９】
原稿画像をスキャナユニット２４で読取って得られた画像データは、後述する画像処理部へ送られ、各種画像処理が施された後、画像処理部のメモリに一旦記憶され、出力指示に応じてメモリ内の画像を読出してレーザ記録部２２に転送して記録媒体である記録紙上に画像を形成させる。
【００９０】
レーザ記録部２１は、記録紙の搬送系３４と、レーザ書き込みユニット３３と、画像を形成するための電子写真プロセス部１１ａとを備える。レーザ書き込みユニット３３は、前述のスキャナユニット２４にて読取られるメモリに記憶された後にメモリから読出される画像データ、または外部の装置から転送される画像データに応じてレーザ光を出射する半導体レーザ光源と、レーザ光を等角速度偏向するポリゴンミラーと、等角速度で偏向されたレーザ光が電子写真プロセス部１１に備えられる感光体１２上で等角速度で偏向されるように補正するｆ−θレンズなどを含む。
【００９１】
電子写真プロセス部１１ａは、前述の感光体１２の周囲に接触式帯電器１３、現像器１５、転写帯電器１６、クリーナ１８が、矢符１９ａで示す感光体１２の回転方向の上流側から下流側に向かってこの順番に備えられる。前述のように感光体１２は、接触式帯電器１３によって一様に帯電され、帯電された状態で、レーザ書込ユニット３３から出射される原稿画像データに対応するレーザ光によって露光される。露光されることによって感光体１２表面に形成される静電潜像は、現像器１５から供給されるトナーによって現像され、可視像であるトナー画像となる。感光体１２表面に形成されたトナー画像は、後述する搬送系３４によって供給される記録紙上に転写帯電器１６によって転写され、定着器１７によって記録紙上に定着される。
【００９２】
記録紙の搬送系３４は、画像形成を行う電子写真プロセス部１１ａの特に転写器１６の配置される転写位置へ記録紙を搬送する搬送部３５と、搬送部３５へ記録紙を送り込むための第１〜第３カセット給紙装置３６，３７，３８と、記録紙を手差し供給するための手差供給装置３９と、トナー画像定着後の記録紙の裏面（トナー画像が形成された面の反対面）に、さらに画像を形成するために記録紙を再供給するための再供給経路４０とを含む。この搬送系３４の搬送経路上には、多数の搬送ローラ４１が設けられ、記録紙は搬送ローラ４１によって搬送系３４内の所定の位置に搬送される。
【００９３】
電子写真プロセス部１１ａの定着器１７によってトナー画像を定着処理された記録紙は、裏面に画像形成するべく再供給経路４０に送給されるか、または排紙ローラ４２によって後処理装置４３へ給送される。再供給経路４０に給送された記録紙には、前述の動作が繰返し実行されて裏面に画像形成される。後処理装置４３に給送された記録紙は、後処理が施された後、後処理工程に応じて定められる排紙先である第１または第２排紙カセット４４，４５のいずれかに排紙されて、画像形成装置１０における一連の画像形成動作が完了する。
【００９４】
接触式帯電器１３を備える画像形成装置１０において、接触式帯電器１３と接する層中にポリシロキサン化合物を特定量含有する電子写真感光体１２を搭載することによって、画像形成装置１０は、高感度で高解像力を有する画像を長期間にわたって安定して形成することができる。
【００９５】
【実施例】
以下に実施例、比較例および試験例を挙げ、本発明を具体的に説明する。以下において、「部」および「％」とあるのは、特に断らない限り、それぞれ「重量部」および「重量％」を意味するものとする。
【００９６】
実施例１
（下引き層の形成）
テトラヒドロフラン９０部に酸化チタン繊維（商品名：ＳＴＲ−６０Ｎ、表面未処理品、堺化学（株）製）５部および共重合ナイロン（商品名：ＣＭ８０００、東レ（株）製）５部を加え、ペイントシェーカーによって１２時間混合して分散させ、固形分１０％の下引き層用塗布液を作製した。得られた下引き層用塗布液を塗布槽に満たし、直径３０ｍｍ、全長２５０ｍｍのアルミニウム製のドラム導電性支持体を浸漬して引き上げ、自然乾燥して膜厚１μｍの下引き層を形成した。
【００９７】
（電荷発生層の形成）
チタニルフタロシアニン１部、ブチラール樹脂（商品名：＃６０００−Ｃ、電気化学工業（株）製）１部および１，３−ジオキソラン９８部を、ペイントコンディショナー装置（レッドレベル社製）によって、直径２ｍｍのガラスビーズを分散助剤としてミリング処理し、電荷発生層用塗布液を調製した。この塗布液に、上記で下引き層を形成した導電性感光体を浸漬して引き上げ、自然乾燥して膜厚０．２μｍの電荷発生層を形成した。
【００９８】
（電荷輸送層）
一般式
【００９９】
【化５】

【０１００】
で表されるブタジエン化合物６０部、一般式
【０１０１】
【化６】

【０１０２】
で表される繰返し単位を有するポリカーボネート（粘度平均分子量５００００）６０部、ビスフェノールＺポリカーボネート（粘度平均分子量２１５００、商品名：ＰＣＺ２００、三菱瓦斯化学（株）製）４０部、２，６−ビス−ｔｅｒｔ−ブチル−４−メチルフェノール（酸化防止剤、商品名：スミライザーＢＨＴ、住友化学工業（株）製）５部およびジメチルポリシロキサン（商品名：ＳＨ２００、東レ・ダウコーニング・シリコーン（株）製）０．３部をテトラヒドロフランに溶解させ、固形分濃度２１％の電荷輸送層用塗布液を調製した。この塗布液に、上記で下引き層および電荷発生層を形成した導電性支持体を浸漬して引き上げ、１１０℃にて１時間乾燥し、膜厚２０μｍの電荷輸送層を形成し、本発明の電子写真感光体を製造した。
【０１０３】
実施例２
ジメチルポリシロキサンの配合量を０．０３部に変更する以外は実施例１と同様に操作し、本発明の感光体を製造した。
【０１０４】
実施例３
ジメチルポリシロキサンの配合量を１．５部に変更する以外は実施例１と同様に操作し、本発明の感光体を製造した。
【０１０５】
実施例４
ジメチルポリシロキサンに代えてメチルフェニルポリシロキサン（商品名：ＫＦ５４、信越シリコーン（株）製）を用いる以外は実施例１と同様に操作し、本発明の電子写真感光体を製造した。
【０１０６】
比較例１
ジメチルポリシロキサンの配合量を０．０２部に変更する以外は実施例１と同様に操作し、電子写真感光体を製造した。
【０１０７】
比較例２
ジメチルポリシロキサンの配合量を２．０部に変更する以外は実施例１と同様に操作し、電子写真感光体を製造した。
【０１０８】
実施例５
（下引き層および電荷発生層の形成）
実施例１と同様にして、直径３０ｍｍ、全長２５０ｍｍのアルミニウム製ドラム状導電性支持体の表面に、膜厚１μｍの下引き層および膜厚０．２μｍの電荷発生層を順次形成した。
【０１０９】
（電荷輸送層の形成）
ジメチルポリシロキサンを使用しない以外は、実施例１と同様にして、電荷発生層の上に膜厚２０μｍの電荷輸送層を形成した。
【０１１０】
（保護層の形成）
ビスフェノールＺ型ポリカーボネート（商品名：ＰＣＺ２００、三菱ガス化学（株）製）１００部、酸化スズ５０部、ジメチルポリシロキサン０．５部および塩化メチレン９００部を、ペイントコンディショナー装置（レッドベル社製）によって、直径２ｍｍのガラスビーズを分散助剤としてミリング処理し、保護層用塗布液を調製した。この塗布液を、電荷輸送層上に円形スライドホッパーにて塗布し、１００℃で１時間加熱乾燥し、膜厚２μｍの保護層を形成し、本発明の電子写真感光体を製造した。
【０１１１】
実施例６
（下引き層の形成）
実施例１と同様にして、直径３０ｍｍ、全長２５０ｍｍのアルミニウム製ドラム状導電性支持体の表面に、膜厚１μｍの下引き層を形成した。
【０１１２】
（電荷輸送物質を含む電荷発生層の形成）
オキソチタニルフタロシアニン（電荷発生物質）８部およびテトラヒドロフラン１００部を混合し、ペイントシェーカーにて分散処理した。この分散液に、一般式（５）のブタジエン化合物７０部、一般式（６）の繰返し単位を有するポリカーボネート（粘度平均分子量５００００）６０部、ポリカーボネート（ＰＣＺ２００）４０部、２，６−ビス−ｔｅｒｔ−ブチル−４−メチルフェノール（スミライザーＢＨＴ）５部、ジメチルポリシロキサン０．５部およびテトラヒドロフラン１１００部を混合し、ボールミル中で２４時間混合し、電荷輸送物質を含む電荷発生層用塗布液を調製した。この塗布液を、下引き層上に円形スライドホッパーにて塗布し、１１０℃で１時間乾燥して電荷輸送物質を含む電荷発生層（膜厚２０μｍ）を形成し、単層型感光体である本発明の電子写真感光体を製造した。
【０１１３】
上記実施例１〜６および比較例１〜２で得られた電子写真感光体をつぎの評価試験に供した。結果を表１に示す。
【０１１４】
〔初期画像の評価〕
接触式帯電器として帯電ブラシを備えているレーザプリンタ（商品名ＬＰ−１２００、セイコーエプソン（株）製）を改造し、上記で得られた電子写真感光体を搭載し、ハーフトーン画像を目視で確認した。このとき、初期電位を８００Ｖに設定して、露光後電位が５０Ｖになるように露光量を設定した。
【０１１５】
〔電位の評価〕
初期画像の評価で用いたレーザプリンタから現像槽を取り出し、代わりに現像部位に表面電位計（商品名：Ｍｏｄｅ３４４、Ｔｒｅｋ社製）を設置し、白ベタ原稿データの電位ＶＯ、ハーフトーン原稿データの電位ＶＨおよび黒ベタ原稿データの電位ＶＬを測定した。
【０１１６】
〔耐久性（繰り返し安定性）の評価〕
初期画像の評価で用いたレーザプリンタによって、同じ初期電位および露光強度の設定で、Ａ４紙１０万枚のコピーを行い、ハーフトーン画像を目視で確認した。
【０１１７】
また、１０万枚のコピー終了後、レーザプリンタの現像槽に代えて表面電位計（Ｍｏｄｅ３４４）を設置し、白ベタ原稿データの電位ＶＯ、ハーフトーン原稿データの電位ＶＨおよび黒ベタ原稿データの電位ＶＬを測定し、繰返し使用時の変化を評価した。
【０１１８】
比較例３
上記評価試験において、レーザプリンタの帯電ブラシをコロナ帯電装置に変更する以外は、実施例１と同様に試験を行った。結果を表１に示す。
【０１１９】
【表１】

【０１２０】
ポリシロキサン化合物をバインダ樹脂１００部に対して０．０２５〜１．５部用いた実施例は、いずれも画像特性および電気特性が良好であった。添加量下限（実施例２）では、画像が僅かに荒れたるけれども、許容範囲内であり、全般には良好であった。また、添加量上限（実施例３）では、やや外観上ムラがあったが実使用上良好に使用できた。ジメチルポリシロキサン以外のポリシロキサン化合物を使用した場合（実施例４）は良好に使用できる。しかしながら、ジメチルポリシロキサンの方が初期感度が一層良く、１０万枚コピー後も残留電位上昇がやや少なく良好である。保護層を形成した場合（実施例５）および単層型感光体の場合（実施例６）は、初期感度が僅かに悪化するけれども良好に使用でき、１０万枚印字後も画像不良は無く良好な結果であった。
【０１２１】
一方、ポリシロキサン化合物の添加量が規程範囲外である比較例１では、１０万枚印字後に感光体表面に紙粉、トナーなどによってキズが入り、フィルミングが発生していた。このため、得られた画像は画質が低下し、画像不良と評価された。また、比較例２ではバインダ樹脂との相溶性が悪くなり、塗工不良が発生し、性能試験を実施することができなかった。比較例３では、コロナ帯電方式に改造し、１０万枚印字する実験を行った。しかしながら、オゾンなどの放電生成物による白抜け画像が発生した。
【０１２２】
【発明の効果】
本発明によれば、接触帯電装置を備える電子写真方式の画像形成装置で用いられる電子写真感光体において、帯電部材に接触する層をバインダ樹脂とポリシロキサン化合物とを含む材料で形成し、かつバインダ樹脂１００重量部に対してポリシロキサン化合物０．０２５〜１．５重量部を配合することによって、高電位および高露光設定下において、残留電位の急激な上昇に基因する濃度低下などの画像不良が発生せず、また、紙粉、トナーなどが感光体表面に付着することによるフィルミング、およびそれにともなう画像不良が発生しない電子写真感光体が得られる。
【０１２３】
本発明によれば、ポリシロキサン化合物の含有量を、バインダ樹脂１００重量部に対して０．０３〜１．５重量部とすることによって、残留電位の上昇、フィルミングの発生などが一層防止される。
【０１２４】
本発明によれば、帯電部材に接触する層を、バインダ樹脂、ポリシロキサン化合物および電荷輸送材料を含む電荷輸送層にすることによって、帯電部材などとの接触に対する耐久性が向上し、感光体の製品寿命が著しく長くなる。
【０１２５】
本発明によれば、ポリシロキサン化合物としてジメチルポリシロキサンを用いることによって、残留電位の上昇、フィルミングの発生などが一層防止される。
【０１２６】
本発明によれば、感光体として本発明の電子写真感光体を用いることによって、高電位および高露光設定において、残留電位の上昇による画像不良の発生およびフィルミングによる画像不良の発生がなく、耐久性に優れ、長期にわたって良好な画像を形成できる画像形成装置が得られる。
【図面の簡単な説明】
【図１】本発明の実施の第１形態である電子写真感光体の断面図である。
【図２】本発明の実施の第２形態である電子写真感光体の断面図である。
【図３】本発明の実施の第３形態である電子写真感光体の断面図である。
【図４】本発明の実施の第４形態である電子写真感光体の断面図である。
【図５】本発明の実施の第５形態である電子写真感光体の断面図である。
【図６】本発明の実施の第６形態である電子写真感光体の断面図である。
【図７】本発明の実施の第７形態である電子写真感光体の断面図である。
【図８】本発明の実施の他の形態である画像形成装置の電子写真プロセス部の概略を示す構成図である。
【図９】本発明の実施の他の形態である画像形成装置の概略を示す構成図である。
【符号の説明】
１ａ，１ｂ，１ｃ，１ｄ，１ｅ，１ｆ，１ｇ 電子写真感光体
２ 導電性支持体
３ 電荷発生層
３ａ 電荷輸送物質を含有する電荷発生層
４ 電荷輸送層
５ ブロッキング層
６ 感光層
７ 保護層
１０ 画像形成装置
１１ 電子写真プロセス部
１２ 電子写真感光体
１３ 接触式帯電器
１４ 露光装置
１５ 現像器
１６ 転写帯電器
１７ 定着装置
１８ クリーナ
１９ 矢符
２０ スキャナ部
２１ レーザ記録部
２２ 原稿載置台
２３ 自動原稿送り装置
２４ スキャナユニット
２５ ランプリフレクタアセンブリ
２６ 第１反射ミラー
２７ 第１走査ユニット
２８ 第２反射ミラー
２９ 第３反射ミラー
３０ 第２走査ユニット
３１ 光学レンズ
３２ 光電変換素子
３３ レーザ書込みユニット
３４ 搬送系
３５ 搬送部
３６ 第１カセット給紙装置
３７ 第２カセット給紙装置
３８ 第３カセット給紙装置
３９ 手差給紙装置
４０ 再供給経路
４１ 搬送ローラ
４２ 排紙ローラ
４３ 後処理装置
４４ 第１排紙カセット
４５ 第２排紙カセット[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member and an image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art In an electrophotographic image forming apparatus such as a copier, a laser printer, and a laser fax, the surface of a photoconductor is charged, an image is exposed to the charged area, an electrostatic latent image is formed, and the electrostatic latent image is developed. The resulting visible image is transferred to a recording medium such as paper, a plastic sheet, a plastic film, or the like, and is recorded as an image. The photoreceptor is obtained by forming a photosensitive layer containing a charge generating substance, a charge transporting substance and the like on the surface of a conductive support. A charging device is used for charging the photoconductor. The charging device is roughly classified into a non-contact charging device and a contact charging device.
[0003]
A non-contact charging device is a charging device that charges a photoconductor without contacting the photoconductor, and a corona charging device that performs charging by corona discharge is used. Examples of the corona charging device include a corotron and a scorotron charge. The corona charging device has an advantage that the photoreceptor can be charged repeatedly and uniformly. However, the corona charging device has a drawback that a large amount of ozone is generated during discharge. Ozone degrades the photosensitive layer on the surface of the photoreceptor and raises the residual potential, causing image defects and adversely affecting the human body. Therefore, ozone is adsorbed by an activated carbon filter. However, the amount of ozone has not been sufficiently reduced. Furthermore, the use of an activated carbon filter hinders downsizing of the device and increases manufacturing costs. Attempts have also been made to lower the potential of the corona charger in order to reduce the amount of ozone generated. However, a satisfactory reduction in ozone generation has not been achieved.
[0004]
A contact charging device is a device that charges a photosensitive member by directly contacting a charging member such as a brush or a roller with the photosensitive member. The contact-type charging device generates less ozone than the corona charging device, and is relatively easy to miniaturize. For this reason, in commercial copying machines, laser printers, and laser facsimile machines, a contact-type charging device is more often used than a corona charging device. By the way, in an electrophotographic system using a contact-type charging device, it is well known that an image defect such as fogging easily occurs due to the direct contact of the charging device with a photoconductor. The occurrence of the image defect itself can be prevented by setting the initial surface potential of the photoconductor to a high potential of 800 V or higher and setting the surface potential after exposure to 50 V or lower. However, by setting such a high potential and high exposure, filming, such as paper powder, toner, and dust in the air, which are transfer materials, adhere to and accumulate on the surface of the photoreceptor, thereby damaging the surface of the photoreceptor. This phenomenon is a new cause of image defects.
[0005]
On the other hand, it has been conventionally known to add a polysiloxane compound to a photosensitive layer of an electrophotographic photosensitive member. For example, a photosensitive layer is formed by applying a coating liquid comprising a charge transport material, a binder resin, dimethylpolysiloxane having an average molecular weight of 1500 to 5000, and an organic solvent on a conductive support. Is 0.015 to 0.025 parts by weight with respect to 100 parts by weight of a binder resin (for example, see Patent Document 1). Although dimethylpolysiloxane prevents the formation of irregularities called soybean skin on the surface of the photosensitive layer, if added in large amounts, the residual potential of the photoreceptor rises sharply, causing image defects such as a decrease in image density. Has disadvantages. For this reason, Patent Literature 1 specifies the upper limit of the content of dimethylpolysiloxane to be 0.025 parts by weight.
[0006]
[Patent Document 1]
JP-A-6-083080
[0007]
[Problems to be solved by the invention]
An object of the present invention is to prevent image defects such as an image density change caused by a sharp rise in residual potential from occurring, and to prevent paper dust and toner from adhering to the surface of a photoreceptor even under high potential and high exposure. Provided is an electrophotographic photoreceptor used in an electrophotographic image forming apparatus employing contact charging, which does not cause filming and an image defect associated therewith, and an image forming apparatus including the electrophotographic photoreceptor. That is.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the inventor of the present invention, in the course of intensive research, in a photoconductor charged by contact with a charging member, a layer contacting the charging member, a polysiloxane compound with respect to 100 parts by weight of the binder resin. When the addition exceeds 0.025 parts by weight, image defects such as image density change due to a sudden increase in residual potential are caused by setting the initial surface potential to about 600 to 800 V and performing exposure after exposure. It has been found that it is time to set the surface potential to a level of 100 V or more.
[0009]
As a result of further research based on this finding, the present inventor has found that in an electrophotographic image recording apparatus having a contact-type charging device, the initial surface potential of the photoreceptor is 800 V or higher, and the surface potential after exposure is 50 V or lower. In such a high potential and high exposure setting, even if the polysiloxane compound is added in excess of 0.025 parts by weight, image defects such as a rapid increase in the residual potential and a resulting insufficient concentration are not generated, and It has been found that when the polysiloxane compound is added in an amount exceeding 0.025 parts by weight, filming due to adhesion of paper powder, toner and the like to the surface of the photoreceptor, and the occurrence of image defects accompanying the filming are prevented. completed.
[0010]
The present invention is an electrophotographic photoreceptor charged by contact with a charging member, wherein a layer in contact with the charging member contains a binder resin and a polysiloxane compound, and the content of the polysiloxane compound is 100 parts by weight of the binder resin. An electrophotographic photoreceptor characterized in that the amount is 0.025 to 1.5 parts by weight.
[0011]
According to the present invention, in an electrophotographic photoreceptor used in an electrophotographic image forming apparatus including a contact charging member, a layer contacting the charging member is formed of a material containing a binder resin and a polysiloxane compound; By blending 0.025 to 1.5 parts by weight of the polysiloxane compound with respect to 100 parts by weight of the resin, fogging due to contact charging and a sudden increase in residual potential can be caused under high potential and high exposure settings. Thus, an electrophotographic photoreceptor can be obtained which does not cause image defects such as a decrease in density and filming due to paper powder, toner and the like adhering to the surface of the photoreceptor, and image defects due to the filming.
[0012]
The reason that the polysiloxane compound exhibits such excellent effects is that, at the high potential and the high exposure setting as described above, a part of the polysiloxane compound is appropriately and stably deposited on the layer in contact with the charging member. Since it is in a molten state, the frictional resistance near the surface of the layer that comes into contact with the charging member is reduced, and a paper member, a toner, and the like are provided so as to slide on the photoconductor and the photoconductor. This is because the state in which the polysiloxane compound is hardly rubbed is maintained even when the polysiloxane compound is sandwiched, and the region that achieves both the friction reduction effect originally possessed by the polysiloxane compound and the smoothing effect (leveling effect or yuzu skin prevention effect) of the coating film is as described above. It can be inferred that the content is within the specified range.
[0013]
The electrophotographic photoreceptor of the present invention is characterized in that the content of the polysiloxane compound is 0.03 to 1.5 parts by weight based on 100 parts by weight of the binder resin.
[0014]
According to the present invention, by setting the content of the polysiloxane compound to 0.03 to 1.5 parts by weight with respect to 100 parts by weight of the binder resin, the increase in the residual potential and the occurrence of filming are further prevented. You.
[0015]
Further, the electrophotographic photoreceptor of the present invention is characterized in that the layer in contact with the charging member is a charge transport layer containing a charge transport material together with a binder resin and a polysiloxane compound.
[0016]
According to the present invention, by making the layer in contact with the charging member a charge transporting layer containing a binder resin, a polysiloxane compound and a charge transporting material, durability against contact with the charging member and the like is improved, and Product life is significantly prolonged.
[0017]
The electrophotographic photoreceptor of the present invention is characterized in that the polysiloxane compound is dimethylpolysiloxane.
[0018]
According to the present invention, the use of dimethylpolysiloxane as the polysiloxane compound can further prevent an increase in the residual potential and the occurrence of filming.
[0019]
The present invention includes an electrophotographic photosensitive member, and after forming a surface of the electrophotographic photosensitive member to a predetermined potential, forms an electrostatic latent image by exposure, and develops the electrostatic latent image with a developer to obtain an electrophotographic photosensitive member. In an image forming apparatus for forming a visible image on the surface of a photographic photoreceptor and transferring and fixing the visible image on a predetermined recording paper to form an image, the electrophotographic photoreceptor may be any one of the above. An image forming apparatus, which is an electrophotographic photosensitive member.
[0020]
According to the present invention, by using the electrophotographic photoreceptor of the present invention as the photoreceptor, at high potential and high exposure setting, there is no occurrence of image failure due to increase in residual potential and occurrence of image failure due to filming. An image forming apparatus which is excellent in property and can form a good image over a long period of time can be obtained.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
The electrophotographic photoreceptor of the present invention may have the same configuration as a conventional electrophotographic photoreceptor, except that a layer in contact with a charging device contains a specific amount of a polysiloxane compound with respect to a binder resin. it can. For example, the electrophotographic photosensitive member shown in FIGS.
[0022]
FIG. 1 is a sectional view of an electrophotographic photosensitive member 1a according to a first embodiment of the present invention. The electrophotographic photosensitive member 1a includes a conductive support 2 and a charge generation layer 3 formed on the surface of the conductive support 2. The electrophotographic photoreceptor 1 contains a polysiloxane compound in the charge generation layer 3.
[0023]
FIG. 2 is a sectional view of an electrophotographic photosensitive member 1b according to a second embodiment of the present invention. The electrophotographic photoreceptor 1b includes a conductive support 2 and a charge generation layer 3a formed on the surface of the conductive support 2 and containing a charge transport material. The electrophotographic photoreceptor 1b contains a polysiloxane compound in the charge generation layer 3a.
[0024]
FIG. 3 is a sectional view of an electrophotographic photosensitive member 1c according to a third embodiment of the present invention. The electrophotographic photoreceptor 1c includes a conductive support 2, a charge generation layer 3 formed on the surface of the conductive support 2, and a charge transport layer 4 formed on the surface of the charge generation layer 3. It consists of. The electrophotographic photoreceptor 1c contains a polysiloxane compound in the charge transport layer 4.
[0025]
FIG. 4 is a sectional view of an electrophotographic photoreceptor 1d according to a fourth embodiment of the present invention. The electrophotographic photoreceptor 1d includes a conductive support 2, a charge transport layer 4 formed on the surface of the conductive support 2, and a charge generation layer 3 formed on the surface of the charge transport layer 4. It consists of. In the electrophotographic photoreceptor 1d, the charge generation layer 3 contains a polysiloxane compound.
[0026]
FIG. 5 is a cross-sectional view of an electrophotographic photosensitive member 1e according to a fifth embodiment of the present invention. The electrophotographic photoreceptor 1e includes a conductive support 2, a blocking layer 5 formed on the surface of the conductive support 2, and a photosensitive layer 6 formed on the surface of the blocking layer 5. You. The photosensitive layer 6 includes one or more layers selected from a charge generation layer 3, a charge generation layer 3a containing a charge transport substance, and a charge transport layer 4. The same applies hereinafter. The electrophotographic photoreceptor 1e contains a polysiloxane compound in the outermost layer with respect to the conductive support 2 among the layers constituting the photosensitive layer 6.
[0027]
FIG. 6 is a sectional view of an electrophotographic photoreceptor 1f according to a sixth embodiment of the present invention. The electrophotographic photoreceptor 1f includes a conductive support 2, a photosensitive layer 6 formed on the surface of the conductive support 2, and a protective layer 7 formed on the surface of the photosensitive layer 6. You. The electrophotographic photoreceptor 1f contains a polysiloxane compound in the protective layer 7.
[0028]
FIG. 7 is a sectional view of an electrophotographic photosensitive member 1g according to a seventh embodiment of the present invention. The electrophotographic photoreceptor 1 g includes a conductive support 2, a blocking layer 5 formed on the surface of the conductive support 2, a photosensitive layer 6 formed on the surface of the blocking layer 5, and a photosensitive layer 6. And a protective layer 7 formed on the surface of the substrate. The electrophotographic photoreceptor 1f contains a polysiloxane compound in the protective layer 7.
Among the electrophotographic photosensitive members 1a to 1g, the electrophotographic photosensitive member 1c is preferable.
[0029]
Hereinafter, a polysiloxane compound contained in a layer of the electrophotographic photoreceptor of the present invention which comes into contact with a charging member, and a conductive support 2, a charge generation layer 3, and a charge transport layer 4 constituting the electrophotographic photoreceptor of the present invention The blocking layer 5, the photosensitive layer 6, and the protective layer 7 will be described in more detail.
[0030]
(Polysiloxane compound)
As the polysiloxane compound, known compounds can be used.
[0031]
Embedded image

[0032]
[Wherein, R ¹ And R ² Is the same or different and represents an alkyl group which may have a substituent, an aryl group which may have a substituent, or an aralkyl group which may have a substituent. ]
And a polysiloxane compound having a structural unit represented by
[0033]
In the general formula (1), R ¹ And R ² Examples of the alkyl group represented by are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl Group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc., a linear or branched alkyl group having 1 to 20 carbon atoms. No. Among them, a linear or branched alkyl group having 1 to 4 carbon atoms is preferable. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenylyl group, and a naphthyl group. Among these, a phenyl group is preferred. Examples of the aralkyl group include 2-phenylethyl, benzyl, 1-phenylethyl, 3-phenylpropyl, 4-phenylbutyl and the like. Among the alkyl group, the aryl group and the aralkyl group, an alkyl group is preferable.
[0034]
Also, R ¹ And R ² Examples of the substituent of the alkyl group, aryl group and aralkyl group represented by are, for example, a halogen atom, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an alkoxycarbonyl group, an acyl group, an acyloxy group, a mercapto group, a cyano group And the like.
[0035]
The polysiloxane compound containing the structural unit represented by the general formula (1) may be composed of one type of structural unit, for example, a polysiloxane compound in which a dialkyl compound and an alkylalkoxyalkyl compound are mixed. As described above, it may be composed of two or more different structural units.
[0036]
Among them, dimethylpolysiloxane, methylphenylpolysiloxane and the like are preferable, and dimethylpolysiloxane is particularly preferable.
[0037]
In the present invention, a commercially available polysiloxane compound can also be used. Specific examples thereof include SH200 (trade name, manufactured by Toray Silicone Co., Ltd.), KF54, and KF96 (all trade names, manufactured by Shin-Etsu Silicone Co., Ltd.).
[0038]
Although the molecular weight of the polysiloxane compound is not particularly limited, it is usually 1,000 to 70,000, preferably 1500 to 30,000. If the molecular weight is significantly smaller than 1000, the effect of the polysiloxane compound as a leveling agent (such as a skin-preventing effect) tends to decrease. On the other hand, if it is significantly larger than 70,000, the compatibility with the binder resin decreases, and the effect of preventing filming tends to be insufficient.
[0039]
The polysiloxane compounds can be used each alone or two or more of them can be used in combination.
The content of the polysiloxane compound is 0.025 to 1.5 parts by weight, preferably 0.03 to 1.5 parts by weight, based on 100 parts by weight of the binder resin. If the amount is less than 0.025 parts by weight, the prevention of filming becomes insufficient, causing image defects. On the other hand, when the amount exceeds 1.5 parts by weight, the compatibility with the binder resin constituting the layer in contact with the charging member and other components to be described later is reduced, so that a coating failure occurs and an image failure may occur. . Further, since the layer in contact with the charging member becomes non-uniform, it cannot withstand actual use.
[0040]
(Conductive support)
Known materials can be used as the conductive support 2. For example, those made of metal such as aluminum, stainless steel, copper, and nickel, insulating films such as resin films (for example, polyester films), paper, and ceramics (for example, glass) can be used. A conductive layer made of a metal or a conductive metal oxide such as aluminum, copper, palladium, tin oxide, or indium oxide formed on the surface of the base, and a conductive powder and a binder resin on the surface of the same insulating base as described above. And a conductive layer formed of a conductive resin composition containing the same. Among these, a metal endless pipe cut into an appropriate length is preferable, and aluminum is particularly preferable. The surface of the conductive support may be subjected to various treatments such as an oxidation treatment and a chemical treatment within a range that does not affect the image quality.
[0041]
(Charge generation layer)
The charge generation layer 3 contains a charge generation substance and a binder resin.
[0042]
Known charge generating substances can be used, for example, selenium and its alloys, inorganic charge generating substances such as arsenic-selenium, cadmium sulfide, cadmium selenide, and zinc oxide; and phthalocyanines (copper, tin, zinc, and vanadium). , Metal phthalocyanines such as oxytitanium and indium chloride, metal phthalocyanines coordinated with oxides or chlorides, metal-free phthalocyanines, etc., azo pigments (monoazo, bisazo, trisazo, polyazos, etc.), quinacridone, polycyclic quinone, pyrylium salts , Indigo, thioindigo, anthantrone, pyranthrone and cyanine. Among these, organic charge generating substances are preferable, and phthalocyanines, azo pigments, and the like are particularly preferable. When the electrophotographic photoreceptor of the present invention is used in an image forming apparatus including an exposure device using a laser beam in a range of 530 to 850 nm, α-type, β-type, Y-type, amorphous-type, Oxytitanium phthalocyanine such as amorphous is preferable, and a mixed crystal or a blend thereof may be used. One kind of the charge generating substance can be used alone, or two or more kinds can be used in combination.
[0043]
Known binder resins can be used, for example, homopolymers, homologous polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylates, methacrylates, vinyl alcohol and ethyl vinyl ether. , Polyvinyl acetal, polycarbonate, polyester, polyamide, polyurethane, cellulose ether, butyral resin, phenoxy resin, silicon resin, epoxy resin and the like. One kind of the binder resin can be used alone, or two or more kinds can be used as a mixture as needed. The amount of the binder resin used is not particularly limited and can be appropriately selected from a wide range. However, it is usually 25 to 500 parts by weight, preferably 60 to 250 parts by weight, based on 100 parts by weight of the charge generating substance.
[0044]
When the charge generation layer 3 is a charge generation layer 3a containing a charge transport material, one or more charge transport materials selected from the charge transport materials listed in the item of the charge transport layer 4 described below can be used as the charge transport material. The content of the charge transporting substance is not particularly limited and can be appropriately selected from a wide range, but is usually 10 to 200 parts by weight, preferably 20 to 80 parts by weight based on 1 part by weight of the charge generating substance. At this time, the binder resin is used usually in an amount of 100 to 1000 parts by weight, preferably 200 to 300 parts by weight, based on 100 parts by weight of the total amount of the charge generating substance and the charge transporting substance.
[0045]
When the charge generation layer 3 is the outermost layer with respect to the conductive support 2, the charge generation layer 3 contains a polysiloxane compound together with a binder resin and a charge generation substance. As described above, the content of the polysiloxane compound is 0.0025 to 1.5 parts by weight, preferably 0.03 to 1.5 parts by weight, based on 100 parts by weight of the solid content of the binder resin.
[0046]
Further, the charge generation layer 3 may be formed of, for example, a plasticizer, an antioxidant, an ultraviolet absorber, a leveling agent, a curling prevention agent in order to improve film forming properties, flexibility, applicability, mechanical strength, and other performances. It may contain one or more additives, such as an agent, conventionally added to the charge generation layer.
[0047]
The charge generation layer 3 is prepared by dissolving or dispersing a binder resin, a charge generation substance, and, if necessary, a charge transport substance and a polysiloxane compound in an appropriate solvent to prepare a coating solution. This is formed by applying to a conductive support provided with a layer of and drying. As the solvent, those capable of dissolving or dispersing the above components can be used. For example, benzene, toluene, xylene, aromatic hydrocarbons such as monochlorobenzene, dioxane, 1,3-dioxolan, ethers such as dimethoxymethyl ether, Examples include amides such as dimethylformamide, lower alcohols such as methanol, ethanol, propanol, and butanol; nitriles such as acetonitrile; ketones such as methyl ethyl ketone; and tetrahydrofuran. One kind of the solvent can be used alone, or two or more kinds can be used as a mixture as needed. The amount of the solvent to be used is not particularly limited, and an amount that can dissolve or disperse each component and facilitates application to the conductive support may be appropriately selected according to the amount of each component used. As the application method, a known method can be adopted, and examples thereof include methods such as roll coating, bar coating, dip coating, spray coating, blade coating, and ring coating. The amount of the coating solution applied is not particularly limited. However, the coating solution is usually applied so that the film thickness after drying is 0.05 to 5 μm, preferably 0.1 to 1 μm. Drying may be natural drying or heat drying. The heating and drying is usually performed at a temperature of about 40 to 120 ° C., and is completed in about 10 minutes to 1 hour.
[0048]
The charge generation layer 3 may be a layer formed by depositing a charge generation substance. The film formation of the charge generating substance is performed by a known method such as a vapor deposition method such as vacuum deposition, ion plating, and chemical vapor deposition, and a sputtering method. In order to include the charge transporting substance in the charge generation material film-forming layer, the binder resin and the charge transporting substance may be dissolved or dispersed in a solvent, impregnated into the film-forming layer, and dried. In order to include the polysiloxane compound in the charge generation substance film-forming layer, the binder resin and the polysiloxane compound may be dissolved or dispersed in a solvent, and this may be impregnated into the film-forming layer and dried. In any case, the same binder resin and solvent as described above can be used.
[0049]
(Charge transport layer)
The charge transport layer 4 contains a charge transport material and a binder resin.
[0050]
Known charge-transporting substances can be used, for example, polyvinyl-N-vinylcarbazole and its derivatives, polycarbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole Derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline derivatives, phenylhydrazones, hydrazones Derivatives, triphenylamine-based compounds, tetraphenyldiamine-based compounds, triphenylmethane-based compounds, stilbene-based compounds, and compounds having a 3-methyl-2-benzothiazoline ring Electron-donating charge transport materials such as benzophenone compounds, fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyano oxide derivatives Examples thereof include electron-accepting charge transporting substances such as ethylene, tetracyanoquinodimethane, promanyl, chloranil, benzoquinone, butadiene compounds, styryl compounds, and amine compounds. Among them, butadiene-based compounds, styryl-based compounds, amine compounds, and the like are preferable, from the viewpoint that high hole transporting ability is high and high sensitivity can be maintained even when the binder resin ratio is high. Specific examples of the butadiene compound include, for example, those represented by the general formula
[0051]
Embedded image

[0052]
[Wherein, Ar ₁ , Ar ₂ , Ar ₃ And Ar ₄ Represents an aryl group which may have a substituent; ₁ ~ Ar ₄ Is an aryl group having a substituted amino group as a substituent. n represents 0 or 1. ]
Butadiene compounds represented by the formula: Specific examples of styryl compounds include, for example, those represented by the general formula
[0053]
Embedded image

[0054]
[Wherein, Ar ₅ Represents an aryl group which may have a substituent. Ar ₆ Represents a phenylene group, a naphthylene group, a biphenylene group or an anthrylene group which may have a substituent. R ₁₇ Represents a hydrogen atom, a lower alkyl group or a lower alkoxy group. X represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. Y represents an aryl group which may have a substituent or the like. ]
And the like. As the amine compound, for example, a compound represented by the general formula
[0055]
Embedded image

[0056]
[Wherein, R ₁₈ ~ R ₂₃ Represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. p, q, t and u each represent an integer of 1 to 5. r and s represent an integer of 1 to 4. ]
And the like. The charge transport materials may be used each alone or two or more of them may be used in combination.
[0057]
It is preferable that the binder resin has good compatibility with the charge transport material and does not cause crystallization or phase separation of the charge transport material after the formation of the charge transport layer 4. Specific examples thereof include, for example, homopolymers, homologous polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinyl alcohol, and ethyl vinyl ether, polyvinyl acetal, and polycarbonate. , Polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, epoxy resin and the like. Among these, those having high mechanical strength and at least partially compatible with the polysiloxane compound are preferable. In this respect, polycarbonate, polyarylate, a mixture thereof and the like are preferable. One kind of binder resin can be used alone, or two or more kinds can be used in combination as needed. Although the content of the binder resin is not particularly limited and can be appropriately selected from a wide range, it is usually 60 to 300 parts by weight, preferably 140 to 250 parts by weight, based on 100 parts by weight of the charge transporting substance.
[0058]
When the charge transport layer 4 is the outermost layer with respect to the conductive support 2, the charge transport layer 4 contains a polysiloxane compound together with a charge transport material and a binder resin. As described above, the content of the polysiloxane compound is 0.025 to 1.5 parts by weight, preferably 0.03 to 1.5 parts by weight, based on 100 parts by weight of the solid content of the binder resin.
[0059]
The charge transport layer 4 may contain an electron-accepting compound, an antioxidant, and the like, in addition to the binder resin and the charge transport material. The electron-accepting compound is other than the electron-accepting charge transporting substance. Examples thereof include a cyano compound of an aromatic ester having a tetracyanoquinodimethane, a dicyanoquinomethane, a dicyanoquinovinyl group, and 2,4,6-triene. Nitro compounds such as nitrofluorenone, fused polycyclic aromatic compounds such as perylene, diphenoquinone derivatives, quinones, aldehydes, ketones, esters, acid anhydrides, phthalides, substituted and unsubstituted metal complexes of salicylic acid, substituted and Metal salts of unsubstituted salicylic acid, metal complexes of aromatic carboxylic acids, metal salts of aromatic carboxylic acids and the like can be mentioned. Among these, cyano compounds, condensed polycyclic aromatic compounds, diphenoquinone derivatives, metal complexes of substituted and unsubstituted salicylic acids, substituted and unsubstituted metal salts, metal complexes of aromatic carboxylic acids, metal salts of aromatic carboxylic acids, etc. Is preferred. One kind of the electron accepting compound can be used alone, or two or more kinds can be used in combination. As the antioxidant, known antioxidants added to resins and the like can be used. For example, vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkane and derivatives thereof, organic sulfur compounds, organic Phosphorus compounds and the like. One kind of antioxidant can be used alone, or two or more kinds can be used in combination.
[0060]
Further, the charge transport layer 4 is formed of a plasticizer, an antioxidant, an ultraviolet absorber, a pigment, a leveling agent, a curling prevention agent, in order to improve film formability, flexibility, applicability, mechanical strength, and other properties. It may contain one or more kinds of additives conventionally added to the charge transport layer, such as an agent and a sensitizer.
[0061]
The charge transporting layer 4 is formed by dissolving or dispersing a charge transporting substance, a binder resin, and, if necessary, an electron-accepting compound, an antioxidant, and other additives in a solvent. Can be formed by applying the composition to a conductive support provided with a layer and drying the composition. This series of operations can be performed in the same manner as in the case where the charge generation layer 3 is formed. Although the thickness of the charge transport layer 4 is not particularly limited, it is usually 10 to 50 μm, preferably 10 to 35 μm.
[0062]
(Blocking layer)
The blocking layer 5 includes, for example, an undercoat layer and an alumite layer.
[0063]
The undercoat layer contains a binder resin. Known binder resins can be used, for example, polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, casein, gelatin, polyethylene, polyester, phenol Resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, polyacrylic acid, polyamide resin and the like. Among these, a polyamide resin having excellent adhesion to a conductive support and having low solubility in a solvent used for a coating solution for the charge generation layer is preferable. One kind of the binder resin can be used alone, or two or more kinds can be used in combination.
[0064]
The undercoat layer may contain metal oxide fine particles such as alumina and titania, and an organic or inorganic dye capable of absorbing laser light, mainly for the purpose of preventing interference fringes in laser exposure. The shape of the metal oxide fine particles is not particularly limited, and examples thereof include needle-like (fibrous), flake-like (scale-like), and particle-like shapes. The content of the metal oxide fine particles and / or the dye is not particularly limited, and can be appropriately selected from a wide range. However, in consideration of the storage stability of the coating solution for forming the undercoat layer comprising the binder resin, the metal oxide fine particles and / or the dye, and the solvent, and the applicability to the conductive support, the binder resin solid content is usually 100% by weight. 40 to 400 parts by weight of metal oxide fine particles and / or dye are used per part.
[0065]
The undercoat layer dissolves or disperses a binder resin and, if necessary, metal oxide fine particles, a dye, and other additives (such as a plasticizer, an antioxidant, an ultraviolet absorber, a leveling agent, and an anti-curl agent) in a solvent. Then, the resulting coating solution is applied to a conductive support, and dried to form a coating. This series of operations can be performed in the same manner as when forming the charge generation layer. The thickness of the undercoat layer is not particularly limited, but is usually 0.1 to 10 μm, preferably 0.2 to 5 μm.
[0066]
The alumite layer can be formed by anodizing the conductive support. Anodization can be performed according to a known method. For example, a conductive support made of aluminum or an aluminum alloy may be subjected to a degreasing treatment as required, and then the conductive support may be used as an anode to perform electrolysis in an acidic bath. Examples of the acidic bath include chromic acid, sulfuric acid, oxalic acid, boric acid, and sulfamic acid. Although the electrolysis conditions are not particularly limited, the solution temperature of the acidic bath is about 10 to 30 ° C., the applied voltage is about 5 to 150 V, and the current density is 0.1 to 500 A / m. ² It may be about the degree.
[0067]
The alumite layer formed by electrolytic oxidation may be subjected to a sealing treatment.
The sealing treatment can be performed according to a known method, such as immersion in an aqueous solution mainly containing nickel oxide, an aqueous solution mainly containing nickel fluoride, an aqueous solution of dichromate, and an aqueous solution of sodium silicate, and steam. Treatment, boiling water treatment, treatment for impregnating resin, and the like.
[0068]
The thickness of the alumite layer is not particularly limited, but is usually 1 to 20 μm, preferably 3 to 15 μm.
[0069]
(Photosensitive layer)
The photosensitive layer 6 includes one or more layers selected from a charge generation layer 3, a charge generation layer 3a containing a charge transport material, and a charge transport layer 4. The charge generation layer 3, the charge generation layer 3a containing the charge transport substance, and the charge transport layer 4 are as described above.
[0070]
When the photosensitive layer 6 is the outermost layer with respect to the conductive support 2, the outermost layer with respect to the conductive support 2 among the layers constituting the photosensitive layer 6 has a binder resin of 100 wt. 0.025 to 1.5 parts by weight, preferably 0.03 to 1.5 parts by weight, of a polysiloxane compound is contained.
[0071]
(Protective layer)
The protective layer 7 contains a binder resin. Furthermore, since the protective layer 7 is provided as the outermost layer with respect to the conductive support 2 in the electrophotographic photoreceptor of the present invention, it contains a polysiloxane compound.
[0072]
As the binder resin, an electrically inactive one can be used. For example, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, acrylic resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyacrylate Examples include allyl sulfone, polybutylene, polybutylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, and epoxy resin. Further, among these binder resins, those which can be cured by a curing agent may contain a curing agent. The binder resin can be used alone or in combination of two or more.
[0073]
As described above, the content of the polysiloxane compound is 0.025 to 1.5 parts by weight, preferably 0.3 to 1.5 parts by weight, based on 100 parts by weight of the solid content of the binder resin.
[0074]
The protective layer 7 may include a polymer charge transport material. Examples of the polymer charge transporting material include those described above as the charge transporting material. Examples thereof include polyvinyl-N-vinylcarbazole and its derivatives, polycarbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, Polyvinyl pyrene, polyvinyl phenanthrene and the like can be mentioned. One kind of the polymer charge transport material can be used alone, or two or more kinds can be used in combination.
[0075]
The protective layer 7 may include a filler for the purpose of improving its wear resistance. Known fillers can be used as the filler, for example, an organic filler such as a fluororesin powder such as polytetrafluoroethylene, a silicone resin powder, an a-carbon powder, a metal powder such as copper, tin, aluminum, and indium; Metal oxides such as tin, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, tin-doped indium oxide, fibrous materials such as potassium titanate, wollastonite, and talc; An inorganic filler such as a flaky or powdery inorganic material may be used. As the filler, one type can be used alone, or two or more types can be used in combination. The average particle size of the filler is not particularly limited and can be appropriately selected from a wide range. However, in consideration of the transmittance of the protective layer, it is usually 0.5 μm or less, preferably 0.2 μm or less.
[0076]
The protective layer 7 includes a binder resin and a polysiloxane compound, and, if necessary, a polymer charge transport material, a filler, and other additives (eg, a plasticizer, an antioxidant, an ultraviolet absorber, a leveling agent, and an anti-curl agent). Is dissolved or dispersed in a solvent, and the resulting coating solution is applied to a conductive support on which another layer is formed, followed by drying. This series of operations can be performed in the same manner as in the case of forming the charge generation layer, except that, for example, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, cyclohexanone, and the like are used as the solvent. Although the thickness of the protective layer 7 is not particularly limited, it is usually 0.01 to 100 μm, preferably 1 to 10 μm.
[0077]
In order to make the charge generation layer 3, the charge generation layer 3a containing the charge transport material, the charge transport layer 4 or the protective layer 7 contain a polysiloxane compound, the polysiloxane compound is added together with the binder resin and other components described above. In addition to the method of dissolving or dispersing in a solvent to form a coating solution and applying this to form each layer, a method of forming each layer containing no polysiloxane compound and impregnating it with a polysiloxane compound or a solution thereof is also available. is there.
[0078]
The electrophotographic photoreceptor of the present invention obtained by forming each layer as described above is an image forming apparatus employing a contact charging system among electrophotographic image forming apparatuses such as a copying machine, a laser printer, and a laser facsimile. Can be suitably used as an electrophotographic photoreceptor.
[0079]
Next, the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 8 is a configuration diagram schematically showing an electrophotographic unit of the image forming apparatus according to the embodiment of the present invention. The electrophotographic section 11 of the image forming apparatus 10 includes an electrophotographic photosensitive member 12, a contact-type charger 13 for charging the electrophotographic photosensitive member 12 to a predetermined potential, and an electrostatic latent image on the surface of the electrophotographic photosensitive member 12. An exposure device 14 for forming, a developing device 15 for developing the electrostatic latent image to form a visible image, a transfer charger 16 for transferring the visible image to a recording medium, And a cleaner 18 for cleaning the surface of the electrophotographic photoreceptor 12.
[0080]
Around the electrophotographic photosensitive member 12, a contact charger 13, an exposure device 14, a developing device 15, a transfer charger 16, a fixing device 17, and a cleaner 18 are arranged in this order. The contact type charger 13 is a contact charging unit using a charging drum or the like.
[0081]
The drum-shaped electrophotographic photosensitive member 12 is driven to rotate at a predetermined peripheral speed in a direction of an arrow 19 by a driving unit (not shown). The photoreceptor 12 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by the contact charger 13 during the rotation process. Next, the light from the exposure device 14 is repeatedly scanned over the surface of the photoconductor 12 in the longitudinal direction (main scanning direction), and an electrostatic latent image is sequentially formed on the peripheral surface of the photoconductor 12. The formed electrostatic latent image is developed as a toner image by a developing device 15 provided downstream of the image forming point in the rotation direction.
[0082]
In synchronization with the exposure of the photoreceptor 12, recording paper as a recording medium is supplied to a transfer charger 16 provided further downstream in the rotation direction of the developing device 15, and a toner image is transferred to the recording paper. The recording paper is conveyed to the fixing device 17 and the toner image is fixed on the recording paper. The recording paper on which the image is formed in this way is discharged. The cleaner 18 is provided together with a charge removing lamp (not shown) further downstream of the transfer charger 16 in the rotation direction and upstream of the contact charger 13 in the rotation direction, and cleans toner remaining on the surface of the photoconductor 12. Further, the contact charger 13 may be provided with a function of cleaning the residual toner on the photoconductor 12, so that the cleaning 18 may be omitted, and further, the photo-elimination process may be omitted.
[0083]
By rotating the photoconductor 12, the above rotation process is repeated, and an image is formed.
[0084]
In the case where the peripheral surface of the photoconductor 12 is negatively charged by the contact-type charger 13, a reversal development process is employed in which a negatively charged toner is attached to an exposed region whose surface charge has been reduced by exposure and developed.
[0085]
Further, the photoconductor 12 may be integrally formed with at least one of the contact-type charging device 13, the developing device 15, and the cleaner 18 to form a process cartridge. For example, a process cartridge in which all of the photoconductor 12, the contact-type charging device 13, the developing device 15 and the cleaner 18 are incorporated, a process cartridge in which the photoconductor 12, the contact-type charging device 13 and the developing device 15 are incorporated, the photoconductor 12 And a process cartridge in which the photosensitive member 12 and the developing device 15 are incorporated. Use of such a process cartridge facilitates replacement in a printer or the like.
[0086]
FIG. 9 is a sectional view showing a configuration of an image forming apparatus 10 according to another embodiment of the present invention. The image forming apparatus 10 generally includes a scanner unit 20 and a recording unit 21. The scanner unit 20 includes a document table 22 made of transparent glass, an automatic document feeder 23 for automatically feeding and conveying the document onto the document table 22, and a document table placed on the document table 22. A scanner unit 24 which is a document image reading unit for scanning and reading an image. The document image read by the scanner unit 20 is sent as image data to an image data input unit described later, and predetermined image processing is performed on the image data. In the automatic document feeder 23, a plurality of documents are set at once on a document tray (not shown) provided in the automatic document feeder 23, and the set documents are automatically placed one by one onto the document table 22. It is a device to supply. Also, the automatic document feeder 23 has a transport path for a one-sided document, a transport path for a two-sided document, and a transport path switching unit so that the scanner unit 24 reads one or both sides of the document according to an operator's selection. , A sensor group for grasping and managing the state of a document passing through each unit, a control unit, and the like.
[0087]
The scanner unit 24 includes a lamp reflector assembly 25 for exposing the surface of the document and a first reflection mirror 26 for reflecting light reflected from the document in order to guide a reflected light image from the document to the photoelectric conversion element 32. A scanning unit 27, a second scanning unit having second and third reflection mirrors 28 and 29 for guiding the reflected light image from the first reflection mirror 26 to the photoelectric conversion element 32, and a reflection light image from the original document. The configuration includes an optical lens 31 for forming an image on a photoelectric conversion element 32 that converts the signal into an electric image signal via the above-described reflection mirrors 26, 28, and 29, and the photoelectric conversion element 32.
[0088]
The scanner unit 20 sequentially feeds and places the documents to be read on the document table 22 by the related operation of the automatic document feeder 23 and the scanner unit 24, and moves the scanner unit 24 along the lower surface of the document table 22. Is moved to read a document image. The first scanning unit 27 scans the original image at a constant speed V along the original placing table 22 in the reading direction of the original image (from left to right in FIG. 2 as viewed from the paper surface). Are scanned in parallel in the same direction at a speed of, for example, 1/2 (V / 2). By the operations of the first and second scanning units 27 and 30, the image of the document placed on the document placing table 22 can be sequentially formed on the photoelectric conversion element 32 line by line to read the image.
[0089]
The image data obtained by reading the original image by the scanner unit 24 is sent to an image processing unit to be described later, and after being subjected to various types of image processing, temporarily stored in a memory of the image processing unit. The image is read out and transferred to the laser recording unit 22 to form an image on a recording paper as a recording medium.
[0090]
The laser recording unit 21 includes a recording paper transport system 34, a laser writing unit 33, and an electrophotographic processing unit 11a for forming an image. The laser writing unit 33 is a semiconductor laser light source that emits a laser beam in accordance with image data read from the memory after being stored in the memory read by the scanner unit 24 or image data transferred from an external device. A polygon mirror that deflects the laser light at an equal angular velocity, and an f-θ lens that corrects the laser light deflected at an equal angular velocity so as to be deflected at a uniform angular velocity on a photoreceptor 12 provided in the electrophotographic process unit 11. including.
[0091]
The electrophotographic process unit 11a includes a contact type charger 13, a developing unit 15, a transfer charger 16 and a cleaner 18 around the photoreceptor 12 described above, which are downstream from the upstream side in the rotation direction of the photoreceptor 12 as indicated by an arrow 19a. Prepared in this order towards the side. As described above, the photoconductor 12 is uniformly charged by the contact-type charger 13, and in the charged state, is exposed to the laser light corresponding to the document image data emitted from the laser writing unit 33. The electrostatic latent image formed on the surface of the photoreceptor 12 by being exposed is developed by the toner supplied from the developing device 15, and becomes a visible toner image. The toner image formed on the surface of the photoconductor 12 is transferred by a transfer charger 16 onto recording paper supplied by a transport system 34 described later, and is fixed on the recording paper by a fixing device 17.
[0092]
The recording paper transport system 34 includes a transport unit 35 that transports the recording paper to a transfer position where the electrophotographic processing unit 11 a that performs image formation, particularly, the transfer unit 16 is disposed, and a second transport unit that feeds the recording paper to the transport unit 35. First to third cassette sheet feeding devices 36, 37, and 38, a manual feed device 39 for manually feeding recording paper, and a back surface of the recording paper after the toner image is fixed (the surface opposite to the surface on which the toner image is formed). ) Further includes a re-supply path 40 for re-supplying the recording paper for forming an image. A number of transport rollers 41 are provided on the transport path of the transport system 34, and the recording paper is transported by the transport rollers 41 to a predetermined position in the transport system 34.
[0093]
The recording paper on which the toner image has been fixed by the fixing unit 17 of the electrophotographic process unit 11a is fed to the re-supply path 40 to form an image on the back surface, or fed to the post-processing device 43 by the paper discharge roller 42. Sent. The above-described operation is repeatedly performed on the recording paper fed to the re-supply path 40 to form an image on the back surface. After the recording paper fed to the post-processing device 43 is subjected to post-processing, the recording paper is discharged to one of the first and second discharge cassettes 44 and 45, which are discharge destinations determined according to the post-processing process. Then, the image forming apparatus 10 completes a series of image forming operations.
[0094]
In the image forming apparatus 10 including the contact type charger 13, by mounting the electrophotographic photosensitive member 12 containing a specific amount of the polysiloxane compound in a layer in contact with the contact type charger 13, the image forming apparatus 10 has high sensitivity. Thus, an image having a high resolution can be stably formed over a long period of time.
[0095]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples, Comparative Examples, and Test Examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.
[0096]
Example 1
(Formation of undercoat layer)
To 90 parts of tetrahydrofuran, 5 parts of titanium oxide fiber (trade name: STR-60N, untreated surface, manufactured by Sakai Chemical Co., Ltd.) and 5 parts of copolymerized nylon (trade name: CM8000, manufactured by Toray Industries, Inc.) were added. The mixture was mixed and dispersed by a paint shaker for 12 hours to prepare a coating liquid for an undercoat layer having a solid content of 10%. The obtained coating liquid for undercoat layer was filled in a coating tank, an aluminum drum conductive support having a diameter of 30 mm and a total length of 250 mm was immersed and pulled up, and naturally dried to form a 1 μm-thick undercoat layer.
[0097]
(Formation of charge generation layer)
1 part of titanyl phthalocyanine, 1 part of butyral resin (trade name: # 6000-C, manufactured by Denki Kagaku Kogyo KK) and 98 parts of 1,3-dioxolane were treated with a paint conditioner (manufactured by Red Level Co., Ltd.) to a diameter of 2 mm. Milling treatment was performed using glass beads as a dispersing aid to prepare a coating solution for a charge generation layer. The conductive photoreceptor on which the undercoat layer was formed was immersed in the coating solution, pulled up, and naturally dried to form a 0.2 μm-thick charge generation layer.
[0098]
(Charge transport layer)
General formula
[0099]
Embedded image

[0100]
60 parts of a butadiene compound represented by the general formula
[0101]
Embedded image

[0102]
60 parts of a polycarbonate having a repeating unit represented by the following formula (viscosity average molecular weight: 50,000), 40 parts of bisphenol Z polycarbonate (viscosity average molecular weight: 21,500, trade name: PCZ200, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 2,6-bis-tert 5 parts of -butyl-4-methylphenol (antioxidant, trade name: Sumilizer BHT, manufactured by Sumitomo Chemical Co., Ltd.) and dimethylpolysiloxane (trade name: SH200, manufactured by Dow Corning Silicone Toray Co., Ltd.) 0 0.3 parts was dissolved in tetrahydrofuran to prepare a charge transport layer coating solution having a solid content of 21%. The conductive support on which the undercoat layer and the charge generation layer were formed was immersed in the coating solution, pulled up, and dried at 110 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm. An electrophotographic photoreceptor was manufactured.
[0103]
Example 2
A photoconductor of the present invention was produced in the same manner as in Example 1, except that the amount of dimethylpolysiloxane was changed to 0.03 part.
[0104]
Example 3
A photoconductor of the present invention was produced in the same manner as in Example 1, except that the amount of dimethylpolysiloxane was changed to 1.5 parts.
[0105]
Example 4
An electrophotographic photoreceptor of the present invention was produced in the same manner as in Example 1, except that methylphenylpolysiloxane (trade name: KF54, manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of dimethylpolysiloxane.
[0106]
Comparative Example 1
An electrophotographic photoreceptor was manufactured in the same manner as in Example 1 except that the amount of dimethylpolysiloxane was changed to 0.02 parts.
[0107]
Comparative Example 2
An electrophotographic photosensitive member was manufactured in the same manner as in Example 1, except that the amount of dimethylpolysiloxane was changed to 2.0 parts.
[0108]
Example 5
(Formation of undercoat layer and charge generation layer)
In the same manner as in Example 1, a 1 μm-thick undercoat layer and a 0.2 μm-thick charge generation layer were sequentially formed on the surface of an aluminum drum-shaped conductive support having a diameter of 30 mm and a total length of 250 mm.
[0109]
(Formation of charge transport layer)
A charge transport layer having a thickness of 20 μm was formed on the charge generation layer in the same manner as in Example 1 except that dimethylpolysiloxane was not used.
[0110]
(Formation of protective layer)
100 parts of bisphenol Z-type polycarbonate (trade name: PCZ200, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 50 parts of tin oxide, 0.5 part of dimethylpolysiloxane and 900 parts of methylene chloride were applied by a paint conditioner (manufactured by Red Bell). Then, milling treatment was performed using glass beads having a diameter of 2 mm as a dispersing aid to prepare a coating solution for a protective layer. This coating solution was applied onto the charge transport layer with a circular slide hopper, and dried by heating at 100 ° C. for 1 hour to form a protective layer having a thickness of 2 μm, thereby producing the electrophotographic photoreceptor of the present invention.
[0111]
Example 6
(Formation of undercoat layer)
In the same manner as in Example 1, an undercoat layer having a thickness of 1 μm was formed on the surface of an aluminum drum-shaped conductive support having a diameter of 30 mm and a total length of 250 mm.
[0112]
(Formation of charge generation layer containing charge transport material)
8 parts of oxotitanyl phthalocyanine (charge generating substance) and 100 parts of tetrahydrofuran were mixed and dispersed by a paint shaker. 70 parts of a butadiene compound of the general formula (5), 60 parts of a polycarbonate having a repeating unit of the general formula (6) (viscosity average molecular weight of 50,000), 40 parts of a polycarbonate (PCZ200), 2,6-bis-tert -Butyl-4-methylphenol (Sumilyzer BHT) (5 parts), dimethylpolysiloxane (0.5 parts) and tetrahydrofuran (1100 parts) were mixed and mixed in a ball mill for 24 hours to prepare a coating liquid for a charge generation layer containing a charge transport material. did. This coating solution is applied on the undercoat layer with a circular slide hopper, and dried at 110 ° C. for 1 hour to form a charge generating layer (20 μm in thickness) containing a charge transporting substance. An electrophotographic photoreceptor of the present invention was manufactured.
[0113]
The electrophotographic photosensitive members obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were subjected to the following evaluation tests. Table 1 shows the results.
[0114]
[Evaluation of initial image]
A laser printer (product name: LP-1200, manufactured by Seiko Epson Corporation) equipped with a charging brush as a contact-type charger was mounted, and the electrophotographic photosensitive member obtained above was mounted thereon, and a halftone image was visually observed. confirmed. At this time, the initial potential was set to 800 V, and the exposure amount was set so that the post-exposure potential became 50 V.
[0115]
[Evaluation of potential]
The developing tank was taken out of the laser printer used in the evaluation of the initial image, and a surface electrometer (trade name: Mode344, manufactured by Trek) was installed at the developing site instead. The potential VO of the solid white original data and the halftone original data The potential VH and the potential VL of solid black original data were measured.
[0116]
[Evaluation of durability (repetition stability)]
Using the laser printer used in the evaluation of the initial image, 100,000 copies of A4 paper were copied under the same initial potential and exposure intensity settings, and the halftone image was visually confirmed.
[0117]
After the copying of 100,000 sheets, a surface electrometer (Mode 344) is installed in place of the developing tank of the laser printer, and the electric potential VO of the solid white original data, the electric potential VH of the halftone original data and the electric potential of the solid black original data are set. The VL was measured and the change during repeated use was evaluated.
[0118]
Comparative Example 3
In the above evaluation test, a test was performed in the same manner as in Example 1 except that the charging brush of the laser printer was changed to a corona charging device. Table 1 shows the results.
[0119]
[Table 1]

[0120]
In each of the examples in which the polysiloxane compound was used in an amount of 0.025 to 1.5 parts with respect to 100 parts of the binder resin, the image characteristics and the electric characteristics were good. At the lower limit of the addition amount (Example 2), although the image was slightly rough, it was within the allowable range and was generally good. In addition, at the upper limit of the amount of addition (Example 3), there was slight unevenness in appearance, but it could be used favorably in practical use. When a polysiloxane compound other than dimethylpolysiloxane is used (Example 4), it can be used favorably. However, the initial sensitivity of dimethylpolysiloxane is better, and the residual potential slightly increases even after copying 100,000 sheets. When the protective layer was formed (Example 5) and in the case of the single-layer type photoreceptor (Example 6), the initial sensitivity was slightly deteriorated, but it could be used well, and there was no image defect even after printing 100,000 sheets. It was a good result.
[0121]
On the other hand, in Comparative Example 1 in which the addition amount of the polysiloxane compound was out of the specified range, the surface of the photoreceptor was scratched by paper dust or toner after printing 100,000 sheets, and filming occurred. For this reason, the obtained image deteriorated in image quality and was evaluated as an image defect. Further, in Comparative Example 2, the compatibility with the binder resin became poor, and coating failure occurred, so that a performance test could not be performed. In Comparative Example 3, an experiment was conducted in which the corona charging method was modified and 100,000 sheets were printed. However, a white image was generated due to a discharge product such as ozone.
[0122]
【The invention's effect】
According to the present invention, in an electrophotographic photoreceptor used in an electrophotographic image forming apparatus including a contact charging device, a layer contacting a charging member is formed of a material containing a binder resin and a polysiloxane compound, and By blending 0.025 to 1.5 parts by weight of the polysiloxane compound with respect to 100 parts by weight of the resin, image defects such as a decrease in density due to a sharp increase in the residual potential under high potential and high exposure settings are prevented. An electrophotographic photoreceptor which does not generate, and which does not cause filming due to paper powder, toner or the like adhering to the surface of the photoreceptor, and image defects accompanying the filming does not occur.
[0123]
According to the present invention, by setting the content of the polysiloxane compound to 0.03 to 1.5 parts by weight with respect to 100 parts by weight of the binder resin, the increase in the residual potential and the occurrence of filming are further prevented. You.
[0124]
According to the present invention, by making the layer in contact with the charging member a charge transporting layer containing a binder resin, a polysiloxane compound and a charge transporting material, durability against contact with the charging member and the like is improved, Product life is significantly prolonged.
[0125]
According to the present invention, by using dimethylpolysiloxane as the polysiloxane compound, an increase in residual potential, occurrence of filming, and the like are further prevented.
[0126]
According to the present invention, by using the electrophotographic photoreceptor of the present invention as a photoreceptor, at high potential and high exposure setting, there is no occurrence of image failure due to increase in residual potential and occurrence of image failure due to filming, and durability An image forming apparatus which is excellent in property and can form a good image over a long period of time is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electrophotographic photosensitive member according to a first embodiment of the present invention.
FIG. 2 is a sectional view of an electrophotographic photosensitive member according to a second embodiment of the present invention.
FIG. 3 is a sectional view of an electrophotographic photosensitive member according to a third embodiment of the present invention.
FIG. 4 is a cross-sectional view of an electrophotographic photosensitive member according to a fourth embodiment of the present invention.
FIG. 5 is a sectional view of an electrophotographic photosensitive member according to a fifth embodiment of the present invention.
FIG. 6 is a sectional view of an electrophotographic photosensitive member according to a sixth embodiment of the present invention.
FIG. 7 is a sectional view of an electrophotographic photosensitive member according to a seventh embodiment of the present invention.
FIG. 8 is a configuration diagram schematically illustrating an electrophotographic processing unit of an image forming apparatus according to another embodiment of the invention.
FIG. 9 is a configuration diagram schematically illustrating an image forming apparatus according to another embodiment of the present invention.
[Explanation of symbols]
1a, 1b, 1c, 1d, 1e, 1f, 1g Electrophotographic photosensitive member
2 Conductive support
3 charge generation layer
3a Charge generation layer containing charge transport material
4 charge transport layer
5 Blocking layer
6 Photosensitive layer
7 Protective layer
10 Image forming apparatus
11 Electrophotographic Process Department
12 Electrophotographic photoreceptor
13 Contact type charger
14 Exposure equipment
15 Developing device
16 transfer charger
17 Fixing device
18 Cleaner
19 Arrow
20 Scanner section
21 Laser recording unit
22 Document Placement Table
23 Automatic Document Feeder
24 Scanner unit
25 Lamp reflector assembly
26 First reflection mirror
27 First scanning unit
28 Second reflection mirror
29 Third reflection mirror
30 Second scanning unit
31 Optical lens
32 photoelectric conversion element
33 Laser writing unit
34 Transport system
35 Transport unit
36 First Cassette Paper Feeder
37 Second cassette paper feeder
38 Third Cassette Paper Feeder
39 Manual paper feeder
40 Resupply route
41 Transport roller
42 Paper ejection roller
43 Post-processing equipment
44 1st paper output cassette
45 2nd paper ejection cassette

Claims (5)

An electrophotographic photoreceptor which is charged by contact with a charging member, wherein a layer in contact with the charging member contains a binder resin and a polysiloxane compound, and the content of the polysiloxane compound is 0.1 to 100 parts by weight of the binder resin. 25 to 1.5 parts by weight of an electrophotographic photosensitive member. 2. The electrophotographic photosensitive member according to claim 1, wherein the content of the polysiloxane compound is 0.03 to 1.5 parts by weight based on 100 parts by weight of the binder resin. 3. The electrophotographic photosensitive member according to claim 1, wherein the layer in contact with the charging member is a charge transport layer containing a charge transport material together with a binder resin and a polysiloxane compound. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the polysiloxane compound is dimethylpolysiloxane. An electrophotographic photosensitive member is provided, and after charging the surface of the electrophotographic photosensitive member to a predetermined potential, an electrostatic latent image is formed by exposure, and the electrostatic latent image is developed with a developer to form an electrophotographic photosensitive member. An image forming apparatus for forming a visible image on a surface and transferring and fixing the visible image to a predetermined recording medium to form an image, wherein the electrophotographic photoreceptor is any one of claims 1 to 4. An image forming apparatus, which is the electrophotographic photosensitive member according to any one of the preceding claims.

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