JP4098130B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Description

【００９１】
式中、Ｍ（中心金属）は、金属及び無金属（水素）の元素を表す。ここであげられるＭ（中心金属）は、Ｈ、Ｌｉ、Ｂｅ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｋ、Ｃａ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｇａ、Ｇｅ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｔｃ、Ｒｕ、Ｒｈ、Ｐｄ、Ａｇ、Ｃｄ、Ｉｎ、Ｓｎ、Ｓｂ、Ｂａ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｏｓ、Ｉｒ、Ｐｔ、Ａｕ、Ｈｇ、ＴＩ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ、Ｔｈ、Ｐａ、Ｕ、Ｎｐ、Ａｍ等の単体、もしく酸化物、塩化物、フッ化物、水酸化物、臭化物などの２種以上の元素からなる。中心金属は、これらの元素に限定されるものではない。本発明におけるフタロシアニン骨格を有する電荷発生物質とは、少なくとも一般式（Ｎ）の基本骨格を有していればよく、２量体、３量体など多量体構造を持つもの、さらに高次の高分子構造を持つものでもかまわない。また基本骨格に様々な置換基があるものでもかまわない。
【００９２】
これらの様々なフタロシアニンのうち、中心金属にＴｉＯを有するオキソチタニウムフタロシアニン、無金属フタロシアニン、クロロガリウムフタロシアニン等は感光体特性上特に好ましい。またこれらのフタロシアニンは、様々な結晶系を持つことが知られており、例えばオキソチタニウムフタロシアニンの場合、α、β、γ、ｍ、Ｙ型等、銅フタロシアニンの場合、α、β、γ等の結晶多系を有している。同じ中心金属を持つフタロシアニンにおいても、結晶系が変わることにより種々の特性も変化する。これらの種々の結晶系を有するフタロシアニン系顔料を用いた感光体の特性もそれに伴って変化することが報告されている（電子写真学会誌第２９巻第４号（１９９０））。このことから、フタロシアニンの結晶系の選択は感光体特性上非常に重要であり、その中でもＹ型オキソチタニウムフタロシアニンは特に高感度化に対し有効かつ有用である。なお、これらの電荷発生物質は、単独又は２種以上の混合物として用いることができる。
【００９３】
電荷発生層３５に用いられる結着樹脂としては、ポリアミド、ポリウレタン、エポキシ樹脂、ポリケトン、ポリカーボネート樹脂、シリコーン樹脂、アクリル樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルケトン、ポリスチレン、ポリ−Ｎ−ビニルカルバゾール、ポリアクリルアミドなどが挙げられる。これらの結着樹脂は、単独又は２種以上の混合物として用いることができる。また、電荷発生層の結着樹脂として前述の結着樹脂の他に、後述の高分子電荷輸送物質（例えば、特開昭６４−１７２８号公報、特開昭６４−１３０６１号公報、特開昭６４−１９０４９号公報、特開平４−１１６２７号公報、特開平４−２２５０１４号公報、特開平４−２３０７６７号公報、特開平４−３２０４２０号公報、特開平５−２３２７２７号公報、特開平６−２３４８３８号公報、特開平６−２３４８３９号公報、特開平６−２９５０７７号公報、特開平７−５６３７４号公報、特開平７−３２５４０９号公報、特開平９−８０７７２号公報、特開平９−８０７８３号公報、特開平９−８０７８４号公報、特開平９−１２７７１３号公報、特開平９−２１１８７７号公報、特開平９−２２２７４０号公報、特開平９−２６５１９７号公報、特開平９−２６５２０１号公報、特開平９−２９７４１９号公報、特開平９−３０４９５６号公報記載）を用いることができる。電荷発生層３５で用いられる結着樹脂の量は電荷発生物質１００重量部に対し、０〜５００重量部、好ましくは０〜２００重量部が適当である。また、必要に応じて、ジメチルシリコーンオイル、メチルフェニルシリコーンオイル等のレベリング剤や増感剤、分散剤等の各種添加剤を添加することができる。
【００９４】
電荷発生層３５を形成する方法には、真空薄膜作製法と溶液分散系からのキャスティング法とが大きく挙げられる。前者の方法には、真空蒸着法、グロー放電分解法、イオンプレーティング法、スパッタリング法、反応性スパッタリング法、ＣＶＤ法等が用いられ、前述した無機系材料、有機系材料が良好に形成できる。また、後述のキャスティング法によって電荷発生層を設けるには、前述の無機系もしくは有機系電荷発生物質を必要に応じて結着樹脂と共にテトラヒドロフラン、ジオキサン、ジオキソラン、トルエン、ジクロロメタン、モノクロロベンゼン、ジクロロエタン、シクロヘキサノン、シクロペンタノン、アニソール、キシレン、メチルエチルケトン、アセトン、酢酸エチル、酢酸ブチル等の溶媒を用いてボールミル、アトライター、サンドミル、ビーズミル等により分散し、分散液を適度に希釈して塗布することにより形成できる。塗布は、浸漬塗工法やスプレーコート、ビードコート、リングコート法など従来公知の方法を用いて行うことができる。以上のようにして設けられる電荷発生層の膜厚は、０．０１〜５μｍ程度が適当であり、好ましくは０．０５〜２μｍである。
【００９５】
電荷輸送層３７は、少なくとも電荷輸送物質及び結着樹脂を適当な溶剤に溶解ないし分散し、これを電荷発生層３５等の上に塗布、乾燥することにより形成できる。
【００９６】
電荷輸送物質としては、正孔輸送物質と電子輸送物質とがある。電子輸送物質としては、たとえばクロルアニル、ブロムアニル、テトラシアノエチレン、テトラシアノキノジメタン、２，４，７−トリニトロ−９−フルオレノン、２，４，５，７−テトラニトロ−９−フルオレノン、２，４，５，７−テトラニトロキサントン、２，４，８−トリニトロチオキサントン、２，６，８−トリニトロ−４Ｈ−インデノ〔１，２−ｂ〕チオフェン−４−オン、１，３，７−トリニトロジベンゾチオフェン−５，５−ジオキサイド、ジフェノキノン誘導体などの電子受容性物質が挙げられる。これらの電子輸送物質は、単独又は２種以上の混合物として用いることができる。
【００９７】
正孔輸送物質としては、以下に表わされる電子供与性物質が挙げられ、良好に用いられる。正孔輸送物質としては、オキサゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、モノアリールアミン誘導体、ジアリールアミン誘導体、トリアリールアミン誘導体、スチルベン誘導体、α−フェニルスチルベン誘導体、ベンジジン誘導体、ジアリールメタン誘導体、トリアリールメタン誘導体、９−スチリルアントラセン誘導体、ピラゾリン誘導体、ジビニルベンゼン誘導体、ヒドラゾン誘導体、インデン誘導体、ブタジェン誘導体、ピレン誘導体等、ビススチルベン誘導体、エナミン誘導体等、その他公知の材料が挙げられる。これらの正孔輸送物質は、単独又は２種以上の混合物として用いることができる。
【００９８】
結着樹脂としては、ポリスチレン、スチレン−アクリロニトリル共重合体、スチレン−ブタジエン共重合体、スチレン−無水マレイン酸共重合体、ポリエステル樹脂、ポリ塩化ビニル、塩化ビニル−酢酸ビニル共重合体、ポリ酢酸ビニル、ポリ塩化ビニリデン、ポリアリレート樹脂、フェノキシ樹脂、アクリル樹脂、メタクリル樹脂、ポリカーボネート樹脂、エポキシ樹脂、メラミン樹脂、ウレタン樹脂、シリコーン樹脂、フッ素樹脂、酢酸セルロース樹脂、エチルセルロース樹脂等が挙げられ、単独でも２種以上の樹脂を混合して用いてもよい。
【００９９】
また、電荷輸送層３７には、結着樹脂としての機能と電荷輸送物質としての機能を持った高分子電荷輸送物質も良好に使用される。これらの高分子電荷輸送物質から構成される電荷輸送層は、耐摩耗性に優れ有効である。本発明においては、これらの高分子電荷輸送物質に前述の結着樹脂や低分子電荷輸送物質を混合して用いることも可能である。高分子電荷輸送物質としては、公知の材料がすべて使用できるが、特に、トリアリールアミン構造を主鎖及び／又は側鎖に含むポリカーボネートが良好に用いられる。中でも、下記の（Ｉ）〜（Ｘ）式で表される高分子電荷輸送物質が良好に用いられる。
【０１００】
【化２】

【０１０１】
［式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立して置換及び／又は無置換のアルキル基又はハロゲン原子、Ｒ_４は水素原子又は置換及び／又は無置換のアルキル基、Ｒ_５、Ｒ_６は置換及び／又は無置換のアリール基、ｏ、ｐ、ｑはそれぞれ独立して０〜４の整数、ｋ、ｊは組成（モル分率）を表し、０．１≦ｋ≦１、０≦ｊ≦０．９の数を表し、ｎは繰り返し単位数を表し５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、又は下記一般式で表される２価基を表す。
【０１０２】
【化３】

【０１０３】
式中、Ｒ_１０１、Ｒ_１０２は各々独立して置換及び／又は無置換のアルキル基、アリール基又はハロゲン原子を表す。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状及び／又は環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（Ｚは脂肪族の２価基を表す）又は、
【０１０４】
【化４】

【０１０５】
（ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換又は無置換のアルキル基又はアリール基を表す）を表す。ここで、Ｒ_１０１とＲ_１０２、Ｒ_１０３とＲ_１０４は、それぞれ同一でも異なってもよい。］
【０１０６】
【化５】

【０１０７】
（式中、Ｒ_７、Ｒ_８は置換及び／又は無置換のアリール基、Ａｒ_１、Ａｒ_２、Ａｒ_３は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１０８】
【化６】

【０１０９】
（式中、Ｒ_９、Ｒ_１０は置換及び／又は無置換のアリール基、Ａｒ_４、Ａｒ_５、Ａｒ_６は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１１０】
【化７】

【０１１１】
（式中、Ｒ_１１、Ｒ_１２は置換及び／又は無置換のアリール基、Ａｒ_７、Ａｒ_８、Ａｒ_９は同一又は異なるアリレン基を表し、ｐは１〜５の整数を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１１２】
【化８】

【０１１３】
（式中、Ｒ_１３、Ｒ_１４は置換及び／又は無置換のアリール基、Ａｒ_１０、Ａｒ_１１、Ａｒ_１２は同一又は異なるアリレン基、Ｘ_１、Ｘ_２は置換及び／又は無置換のエチレン基、又は置換及び／又は無置換のビニレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１１４】
【化９】

【０１１５】
（式中、Ｒ_１５、Ｒ_１６、Ｒ_１７、Ｒ_１８は置換及び／又は無置換のアリール基、Ａｒ_１３、Ａｒ_１４、Ａｒ_１５、Ａｒ_１６は同一又は異なるアリレン基、Ｙ_１、Ｙ_２、Ｙ_３は単結合、置換及び／又は無置換のアルキレン基、置換及び／又は無置換のシクロアルキレン基、置換及び／又は無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表し同一であっても異なってもよい。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１１６】
【化１０】

【０１１７】
（式中、Ｒ_１９、Ｒ_２０は水素原子、置換及び／又は無置換のアリール基を表し、Ｒ_１９とＲ_２０は環を形成していてもよい。Ａｒ_１７、Ａｒ_１８、Ａｒ_１９は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１１８】
【化１１】

【０１１９】
（式中、Ｒ_２１は置換及び／又は無置換のアリール基、Ａｒ_２０、Ａｒ_２１、Ａｒ_２２、Ａｒ_２３は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１２０】
【化１２】

【０１２１】
（式中、Ｒ_２２、Ｒ_２３、Ｒ_２４、Ｒ_２５は置換及び／又は無置換のアリール基、Ａｒ_２４、Ａｒ_２５、Ａｒ_２６、Ａｒ_２７、Ａｒ_２８は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１２２】
【化１３】

【０１２３】
（式中、Ｒ_２６、Ｒ_２７は置換及び／又は無置換のアリール基、Ａｒ_２９、Ａｒ_３０、Ａｒ_３１は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（Ｉ）の場合と同じである。）
【０１２４】
以下、これらトリアリールアミン構造を主鎖及び／又は側鎖に含むポリカーボネートの具体例の幾つかを以下に示すが、本発明はこれら具体例に限定されるものではない。
【０１２５】
【化１４】

【０１２６】
【化１５】

【０１２７】
【化１６】

【０１２８】
【化１７】

【０１２９】
【化１８】

【０１３０】
【化１９】

【０１３１】
【化２０】

【０１３２】
【化２１】

【０１３３】
【化２２】

【０１３４】
【化２３】

【０１３５】
【化２４】

【０１３６】
【化２５】

【０１３７】
【化２６】

【０１３８】
【化２７】

【０１３９】
【化２８】

【０１４０】
【化２９】

【０１４１】
【化３０】

【０１４２】
【化３１】

【０１４３】
【化３２】

【０１４４】
【化３３】

【０１４５】
【化３４】

【０１４６】
【化３５】

【０１４７】
【化３６】

【０１４８】
【化３７】

【０１４９】
【化３８】

【０１５０】
【化３９】

【０１５１】
【化４０】

【０１５２】
【化４１】

【０１５３】
【化４２】

【０１５４】
【化４３】

【０１５５】
【化４４】

【０１５６】
【化４５】

【０１５７】
【化４６】

【０１５８】
【化４７】

【０１５９】
これら主鎖もしくは側鎖にトリアリールアミン構造を有している高分子電荷輸送物質は、単重合体、ランダム共重合体、交互共重合体、ブロック共重合体の形態で重合される。そして、これら高分子電荷輸送物質は結着樹脂としての役割をもつことから被膜形成能を有していることが必要である。そのため、分子量は、ＧＰＣによる測定において、ポリスチレン換算分子量Ｍｗとして１万〜５０万が適当で、好ましくは５万〜４０万である。
これら高分子電荷輸送物質は、特開平８−２６９１８３号公報、特開平９−７１６４２号公報、特開平９−１０４７４６号公報、特開平９−２７２７３５号公報、特開平１１−２９６３４号公報、特開平９−２３５３６７号公報、特開平９−８７３７６号公報、特開平９−１１０９７６号公報、特開平９−２６８２２６号公報、特開平９−２２１５４４号公報、特開平９−２２７６６９号公報、特開平９−１５７３７８号公報、特開平９−３０２０８４号公報、特開平９−３０２０８５号公報、特開２０００−２６５９０号公報に開示されている。
【０１６０】
電荷輸送物質の含有量は、結着樹脂１００重量部に対し、２０〜３００重量部、好ましくは４０〜１５０重量部が適当である。但し、高分子電荷輸送物質を用いる場合は単独でも、他の結着樹脂との併用も可能である。
電荷輸送層３７の塗工に用いられる溶媒としては前記電荷発生層３５と同様なものが使用できる。一例として、テトラヒドロフラン、ジオキサン、ジオキソラン、トルエン、ジクロロメタン、モノクロロベンゼン、ジクロロエタン、シクロヘキサノン、シクロペンタノン、アニソール、キシレン、メチルエチルケトン、アセトン、酢酸エチル、酢酸ブチル等の溶媒を挙げることができるが、電荷輸送物質及び結着樹脂を良好に溶解するものが適している。これらの溶剤は単独で使用しても２種以上混合して使用しても良い。
【０１６１】
電荷輸送層３７には必要に応じて、レベリング剤や酸化防止剤、可塑剤等を添加することが可能である。併用できるレベリング剤としてはジメチルシリコーンオイル、メチルフェニルシリコーンオイル等のシリコーンオイル類や側鎖にパーフルオロアルキル基を有するポリマーあるいはオリゴマーが使用され、その使用量は結着樹脂１００重量部に対して０〜１重量部程度が適当である。
併用できる酸化防止剤としては、フェノール系化合物類、ヒンダードフェノール系化合物類、ヒンダードアミン系化合物類、パラフェニレンジアミン類、ハイドロキノン類、有機硫黄化合物類、有機リン化合物類、ベンゾフェノン類、サルシレート類、ベンゾトリアゾール類、クエンチャー（金属錯塩系）等、従来公知の酸化防止剤をすべて使用することが可能である。また、２種以上の酸化防止剤を混合して添加することにより効果が顕著に高まることがあり、有効である。使用量は、結着樹脂１００重量部に対して０〜５重量％程度が適当である。また、併用できる可塑剤としてはジブチルフタレート、ジオクチルフタレート等の一般的な樹脂の可塑剤として使用されているものがそのまま使用でき、その使用量は結着樹脂１００重量部に対して０〜３０重量部程度が適当である。
【０１６２】
塗工は電荷発生層３５と同様に浸漬塗工法やスプレーコート、ビードコート、リングコート法など公知の方法を用いて行うことができるが、浸漬塗工法が最も好ましく用いられる。電荷輸送層３７の膜厚は、５〜５０μｍ程度が適当であり、解像度、地肌汚れ等の画像特性及び帯電電位、感度等の電気特性上、好ましくは１０〜３０μｍ程度が適当である。
【０１６３】
次に感光層が単層構成３３の場合について述べる。感光層３３は、前述の電荷発生物質、電荷輸送物質、結着樹脂等を適当な溶剤に溶解ないし分散し、これを導電性支持体上に塗工及び乾燥することによって形成される。電荷発生物質及び電荷輸送物質は、前述の電荷発生層３５及び電荷輸送層３７で挙げた材料を使用することが可能である。また、結着樹脂としては、前述の電荷輸送層３７で挙げた樹脂の他に、電荷発生層３５で挙げた樹脂を混合して用いてもよい。また、結着樹脂として前述の高分子電荷輸送物質も良好に使用できる。結着樹脂１００重量部に対する電荷発生物質の量は、５〜４０重量部が好ましく、さらに好ましくは１０〜３０重量部であり、電荷輸送物質の量は０〜１９０重量部が好ましく、さらに好ましくは５０〜１５０重量部である。感光層は、電荷発生物質、結着樹脂を電荷輸送物質とともにテトラヒドロフラン、ジオキサン、ジクロロエタン、シクロヘキサノン、トルエン、メチルエチルケトン、アセトン等の溶剤に溶解ないし分散し、これを浸漬塗工法やスプレーコート、ビードコート、リングコートなどで塗工して形成できる。また、必要により前記の可塑剤やレベリング剤、酸化防止剤、滑剤等の各種添加剤を添加することもできる。感光層３３の膜厚は５〜２５μｍ程度が適当である。
【０１６４】
本発明においては、前記の電荷輸送層、電荷発生層もしくは感光層の上に最表面層として保護層が形成される。
感光体の保護層にはフィラーが含有され、特に耐摩耗性の向上に対して有効である。これらのフィラーとしては、各種有機フィラーや無機フィラーが含まれるが、それらの中でもシリカ、酸化錫、酸化亜鉛、酸化チタン、アルミナ、ジルコニア、酸化インジウム、酸化アンチモン、酸化ビスマス、酸化カルシウム、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等の金属酸化物が耐摩耗性や画質の面から有効に用いられる。これらの金属酸化物の中でも、画像ボケが発生しにくい金属酸化物としては、電気絶縁性が高い金属酸化物の方が好ましい。これらの金属酸化物としては、アルミナ、ジルコニア、酸化チタン等が挙げられる。その中でもアルミナは有効に用いられ、特に光透過性が高く、熱安定性が高い上に、耐摩耗性に優れた六方細密構造であるα型アルミナは、画像ボケの抑制や耐摩耗性の向上、塗膜品質、光透過性等の点から最も有効に使用することができる。一方、導電性金属酸化物を感光体の最表面に含有させた場合には、表面の抵抗が低下することによって電荷の横移動が起こり、画像ボケが発生しやすくなるため、添加量を制限し抵抗を制御することが必要である。これらの金属酸化物としては、酸化錫、酸化亜鉛、酸価インジウム、酸価アンチモン、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等の導電性材料が挙げられる。
【０１６５】
本発明において用いられる金属酸化物は、少なくとも一種の表面処理剤で表面処理を施すことが可能であり有効である。保護層に金属酸化物が含有された感光体は、オゾンやＮＯｘガスにより画像ボケの影響が増加する傾向が見られるが、表面処理剤によって金属酸化物の比抵抗や等電点におけるｐＨを制御することが可能となり、表面処理剤によって画像ボケの抑制効果が大幅に高まる場合がある。金属酸化物の表面処理は、画像ボケの抑制効果だけでなく、金属酸化物の分散性を向上させる効果もあり、塗膜の光透過性の向上、塗膜欠陥の抑制、さらには耐摩耗性の向上や偏摩耗の抑制に対しても有効である。
表面処理剤としては、従来用いられている表面処理剤すべてを使用することができるが、前述の金属酸化物の比抵抗や等電点におけるｐＨを維持できる表面処理剤が好ましい。前述の金属酸化物の等電点におけるｐＨは、表面処理によって変化させることができる。すなわち、酸性処理剤で処理した金属酸化物は酸性側に、塩基性処理剤で処理した金属酸化物は塩基性側に等電点が移動するため、本発明の構成においては、表面処理剤についてもより塩基性を示す処理剤を用いることが、金属酸化物の分散性や画像ボケ抑制の点から好ましい。例えば、チタネート系カップリング剤、アルミニウム系カップリング剤、ジルコアルミネート系カップリング剤等は特に有効に使用することができる。また、Ａｌ_２Ｏ_３、ＴｉＯ_２、ＺｒＯ_２、シリコーン、ステアリン酸アルミニウム等、あるいはそれらの混合処理も金属酸化物の分散性及び画像ボケの点から好ましく用いられる。
【０１６６】
金属酸化物の平均一次粒径は、０．０１〜３．０μｍであることが光透過性や耐摩耗性の点から好ましく、０．１〜１．５μｍがより好ましい。フィラーの平均一次粒径が非常に大きいと、画質劣化を引き起こし、本発明の効果が半減する恐れがある。また、感光体表面に形成される線状傷の幅が非常に大きくなり、それによって電荷の拡散領域が広がって画像流れの抑制効果が低下する。また、フィラーの沈降性が高くなり、液寿命が低減する恐れもある。フィラーの平均一次粒径がこれよりも小さいと、凝集性が高くなり、耐摩耗性の低下を引き起こす場合がある。フィラーの平均一次粒径を０．０１〜３．０μｍの範囲にすることにより、画質劣化が抑制され、感光体表面に形成される線状傷の幅も狭くすることが可能となり、それによって画像流れの抑制効果を高めることが可能となる。上記フィラーの分散性を高めるために、各種添加剤を添加することが可能であり有用である。特に、カルボン酸化合物は、金属酸化物の分散性やその安定性を高めるだけでなく、金属酸化物を添加したことによる残留電位上昇を抑制することが可能となる。その中でもポリカルボン酸系の湿潤分散剤は、それらの効果が高く非常に有効である。カルボン酸化合物としては、一般に知られている有機脂肪酸や高酸価樹脂あるいは共重合体等、分子構造中にカルボキシル基を含む化合物であればすべて使用することができる。例えば、ラウリン酸、ステアリン酸、アラキジン酸、ベヘン酸、アジピン酸、オレイン酸、マレイン酸、無水マレイン酸、サリチル酸、フタル酸、イソフタル酸、テレフタル酸、ピロメリット酸等の飽和脂肪酸及び不飽和脂肪酸、芳香族カルボン酸等の如何なるカルボン酸をも使用することが可能である。また、飽和ポリエステル、不飽和ポリエステル、末端カルボン酸不飽和ポリエステル、スチレン−マレイン酸共重合体、スチレン−無水マレイン酸等、飽和もしくは不飽和の炭化水素を基本骨格とし、少なくとも一つ以上のカルボキシル基が結合されたポリマーやオリゴマーあるいはコポリマーはすべて含まれ、残留電位上昇を抑制する効果だけでなく、金属酸化物の分散性を向上させる効果が高いことから、より有効に用いられる。これらのカルボン保護層の結着樹脂には、高分子電荷輸送物質も有効に使用することが可能であり、電荷輸送層で記載された高分子電荷輸送物質はもちろん、如何なる高分子電荷輸送物質も有効に用いることができる。高分子電荷輸送物質を用いることによって、静電特性上残留電位や感度を維持しつつ、感光体の耐摩耗性や耐傷性を向上させることが可能となる。
【０１６７】
感光体の保護層にはさらに電荷輸送物質を含有させることも可能である。保護層に電荷輸送物質を含有させることによって残留電位の低減や感度劣化の抑制が可能となる。保護層に用いられる電荷輸送物質は、前述の電荷輸送層に記述されたすべての電荷輸送物質を使用することが可能である。
【０１６８】
感光体の保護層には、さらに各種酸化防止剤を添加することが可能であり有用である。本発明において含有される酸化防止剤には、フェノール系化合物類、ヒンダードフェノール系化合物類、ヒンダードアミン系化合物類、パラフェニレンジアミン類、ハイドロキノン類、有機硫黄化合物類、有機リン化合物類、ベンゾフェノン類、サルシレート類、ベンゾトリアゾール類、クエンチャー（金属錯塩系）等、従来公知の酸化防止剤、紫外線吸収剤、光安定剤等の添加剤がすべて含まれる。これらの酸化防止剤の中でも、長期間の繰り返し使用によるオゾンやＮＯｘ等の活性ガスから感光体の劣化を抑制し、画質安定性を高める上で効果が大きなものとしては、特にヒンダードフェノール構造とヒンダードアミン構造の両構造を有する化合物が有用であることが知られている。ヒンダードフェノール構造とは、フェノール性水酸基の両オルト位に嵩高い原子団が存在する構造を示す。一方、ヒンダードアミン構造とは、アミノ窒素原子近傍に嵩高い原子団が存在する構造を示し、芳香族アミンや脂肪族アミン系物質もこれに該当するが、より好ましくは２，２，６，６−テトラメチルピペリジン構造を含んでいる化合物である。これらの両構造を有する化合物の作用機構の詳細は明らかではないが、嵩高い原子団が存在することにより立体障害が高められたことによって、アミノ窒素原子やフェノール性水酸基の熱振動を抑制し、ラジカル状態の安定性が高められたことによって外部からの活性ガスの影響を食い止めることができたものと推定される。ヒンダードフェノール構造とヒンダードアミン構造の両構造を有する化合物としては、種々のものが挙げられるが、中でも下記構造式で表される１−［２−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕エチル］−４−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕−２，２，６，６−テトラメチルピリジンは特にオゾンやＮＯｘガスによる解像度低下に対し有効かつ有用である。
【０１６９】
【化４８】

（Ｈ）
【０１７０】
感光体の保護層には、感光体に滑り性を付与する添加剤を添加することも可能であり、感光体の離型性を高めたり、耐摩耗性を高めたり、異物付着を抑制したりする上で非常に有効である。保護層に含有される滑り性を付与する化合物としては、添加することによって滑り性が付与されれば、いかなる材料を用いてもよいが、特にシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物が有効に用いられる。シリコーン系化合物とは、分子構造にＳｉを含有するものであればいかなるものでも含まれ、例えばシリコーンオイル、各種変性シリコーンオイル、シリコーン樹脂並びに樹脂微粒子などが挙げられる。フッ素系化合物とは、分子構造にＦを含んでいるものであればいかなるものでも含まれ、フッ素変性シリコーンオイル、ＰＴＦＥ・ＰＦＡ・ＰＶＤＦ等の各種フッ素樹脂並びに樹脂微粒子等が挙げられる。また、長鎖アルキル基含有化合物としては、長鎖アルキル基を含有する材料であればいかなるものでも含まれる。炭素数としてはＣ１０、好ましくはＣ１２以上が特に有効である。特に、金属石鹸類も好適に用いられ、その中でもステアリン酸亜鉛は有効かつ有用である。
保護層形成用塗工液に用いられる有機溶剤としては、テトラヒドロフラン、ジオキサン、ジオキソラン、トルエン、ジクロロメタン、モノクロロベンゼン、ジクロロエタン、シクロヘキサノン、シクロペンタノン、アニソール、キシレン、メチルエチルケトン、アセトン、酢酸エチル、酢酸ブチル等が挙げられ、これらの混合溶媒も有効に用いられる。一方、フィラーの分散手段としてはボールミル、アトライター、サンドミル、ビーズミル、超音波等、従来公知の分散手段をすべて用いることが可能である。あるいは、バンバリーミキサー、ロールミル、２軸押出し機などの公知の装置を用い機械的に混合しペレット状に賦形する方法を挙げることもできる。押し出し賦形されたペレットは、幅広い温度範囲で成型可能であり、成型には通常の射出成型機が用いられる。
保護層の形成には、浸漬塗工法、スプレーコート、ビートコート、ノズルコート、スピナーコート、リングコート等、従来の塗工方法を用いることができる。この中でも膜厚制御がしやすく、フィラーの分散性を良好に維持することが可能となり、さらに塗膜品質についても優位性があることからスプレーコートがより好ましい。
塗工された感光体は、加熱による乾燥工程を経て製造される。保護層の膜厚としては、０．５μｍ〜１０μｍが好ましく、２μｍ〜６μｍがより好ましい。
【０１７１】
本発明においては、感光体の最表面に形成されるフィラーを含む保護層の表面に交差する微少な無数の線状傷が連続的に形成される。図４、図５、図６には本発明の感光体表面を表す一例を、図７、図８には形成した線状傷の断面図の一例を示した。本発明においては、フィラーを含む保護層に交差する無数の線状傷が形成されていればいかなる感光体も含まれる。このように、少なくとも２方向の無数の線状傷が交差することによって、いかなる方向に対する画像流れをも抑制することが可能となる。保護層に形成される線状傷はどのような形状でもよく、形成される線状傷の方向については特に限定されるものではない。また、線状傷は必ずしも直線である必要はなく、ある方向性を有していれば線状傷が曲線を描いていたり、波線を描いていたりしてもよい。線状傷は少なくとも２方向から交差することが画像流れを抑制する上で必要であるが、３方向あるいは４方向とより多く交差させることにより、電荷の拡散領域が限定されやすくなるため、画像流れの抑制に対し有効となる。また、形成される線状傷の幅が細いほど電荷の拡散幅が縮小され、高画質化に対し有利である。トナー幅よりも線状傷の幅の方が大きい場合には、トナー粒子が線状傷に入り込み、感光体を汚染させる恐れがあるため、少なくともトナー粒径よりも小さい方が好ましい。
【０１７２】
感光体表面に交差する線状傷を形成させる手段としては、特に限定されるものではなく、従来公知の方法を応用することができる。作製された感光体の保護層に線状傷を形成したり、保護層を積層している段階で線状傷を形成することも可能であり、例えば作製された感光体の保護層表面に直接研磨物を当接して擦る方法、感光体の保護層表面に凹凸を有する金型を押し当てる方法、感光体の保護層を塗工している段階で線状傷を形成する方法等、いかなる方法を応用することが可能である。感光体の保護層表面に当接させる研磨物としては、天然繊維、化学繊維、ガラス繊維、フェルト、布等の繊維類、サンドペーパー等のペーパー類、フィルム等のプラスチック類など、感光体の保護層表面に線状傷を形成させるものであればいかなる形状及び材質のものであっても使用できる。
【０１７３】
本発明の感光体においては、導電性支持体３１と感光層３３との間に下引き層を設けることができる。下引き層は一般には樹脂を主成分とするが、これらの樹脂はその上に感光層を溶剤で塗布することを考えると、一般の有機溶剤に対して耐溶剤性の高い樹脂であることが望ましい。このような樹脂としては、ポリビニルアルコール、カゼイン、ポリアクリル酸ナトリウム等の水溶性樹脂、共重合ナイロン、メトキシメチル化ナイロン等のアルコール可溶性樹脂、ポリウレタン、メラミン樹脂、フェノール樹脂、アルキッド−メラミン樹脂、エポキシ樹脂等、三次元網目構造を形成する硬化型樹脂等が挙げられる。また、下引き層にはモアレ防止、残留電位の低減等のために酸化チタン、シリカ、アルミナ、酸化ジルコニウム、酸化スズ、酸化インジウム等で例示できる金属酸化物の微粉末顔料を加えてもよい。
これらの下引き層は、前述の感光層の如く適当な溶媒及び塗工法を用いて形成することができる。更に本発明の下引き層として、シランカップリング剤、チタンカップリング剤、クロムカップリング剤等を使用することもできる。この他、本発明の下引き層には、Ａｌ_２Ｏ_３を陽極酸化にて設けたものや、ポリパラキシリレン（パリレン）等の有機物やＳｉＯ_２、ＳｎＯ_２、ＴｉＯ_２、ＩＴＯ、ＣｅＯ_２等の無機物を真空薄膜作成法にて設けたものも良好に使用できる。このほかにも公知のものを用いることができる。下引き層の膜厚は０〜５μｍが適当である。
【０１７４】
本発明の感光体においては、下引き層と感光層との間あるいは感光層と保護層との間に中間層を設けることも可能である。中間層には、一般にバインダー樹脂を主成分として用いる。これら樹脂としては、ポリアミド、アルコール可溶性ナイロン、水溶性ポリビニルブチラール、ポリビニルブチラール、ポリビニルアルコールなどが挙げられる。中間層の形成法としては、前述のごとく一般に用いられる塗布法が採用される。なお、中間層の厚さは０．０５〜２μｍ程度が適当である。
【０１７５】
本発明においては、耐環境性の改善のため、とりわけ、感度低下、残留電位の上昇を防止する目的で、電荷発生層、電荷輸送層、下引き層、保護層、中間層等の少なくとも１層ないし各層に、酸化防止剤、可塑剤、滑剤、紫外線吸収剤、低分子電荷輸送物質及びレベリング剤を添加することが出来る。これらの化合物の代表的な材料を以下に記す。
【０１７６】
各層に添加できる酸化防止剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
（ａ）フェノール系化合物
２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ブチル化ヒドロキシアニソール、２，６−ジ−ｔ−ブチル−４−エチルフェノール、ｎ−オクタデシル−３−（４’−ヒドロキシ−３’，５’−ジ−ｔ−ブチルフェノール）、２，２’−メチレン−ビス−（４−メチル−６−ｔ−ブチルフェノール）、２，２’−メチレン−ビス−（４−エチル−６−ｔ−ブチルフェノール）、４，４’−チオビス−（３−メチル−６−ｔ−ブチルフェノール）、４，４’−ブチリデンビス−（３−メチル−６−ｔ−ブチルフェノール）、１，１，３−トリス−（２−メチル−４−ヒドロキシ−５−ｔ−ブチルフェニル）ブタン、１，３，５−トリメチル−２，４，６−トリス（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）ベンゼン、テトラキス−［メチレン−３−（３’，５’−ジ−ｔ−ブチル−４’−ヒドロキシフェニル）プロピオネート］メタン、ビス［３，３’−ビス（４’−ヒドロキシ−３’−ｔ−ブチルフェニル）ブチリックアッシド］グリコールエステル、トコフェロ−ル類などがある。
（ｂ）パラフェニレンジアミン類
Ｎ−フェニル−Ｎ’−イソプロピル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジ−ｓｅｃ−ブチル−ｐ−フェニレンジアミン、Ｎ−フェニル−Ｎ−ｓｅｃ−ブチル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジ−イソプロピル−ｐ−フェニレンジアミン、Ｎ，Ｎ’−ジメチル−Ｎ，Ｎ’−ジ−ｔ−ブチル−ｐ−フェニレンジアミンなどがある。
（ｃ）ハイドロキノン類
２，５−ジ−ｔ−オクチルハイドロキノン、２，６−ジドデシルハイドロキノン、２−ドデシルハイドロキノン、２−ドデシル−５−クロロハイドロキノン、２−ｔ−オクチル−５−メチルハイドロキノン、２−（２−オクタデセニル）−５−メチルハイドロキノンなどがある。
（ｄ）有機硫黄化合物類
ジラウリル−３，３’−チオジプロピオネート、ジステアリル−３，３’−チオジプロピオネート、ジテトラデシル−３，３’−チオジプロピオネートなどがある。
（ｅ）有機燐化合物類
トリフェニルホスフィン、トリ（ノニルフェニル）ホスフィン、トリ（ジノニルフェニル）ホスフィン、トリクレジルホスフィン、トリ（２，４−ジブチルフェノキシ）ホスフィンなどがある。
【０１７７】
各層に添加できる可塑剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
（ａ）リン酸エステル系可塑剤
リン酸トリフェニル、リン酸トリクレジル、リン酸トリオクチル、リン酸オクチルジフェニル、リン酸トリクロルエチル、リン酸クレジルジフェニル、リン酸トリブチル、リン酸トリ−２−エチルヘキシル、リン酸トリフェニルなどがある。
（ｂ）フタル酸エステル系可塑剤
フタル酸ジメチル、フタル酸ジエチル、フタル酸ジイソブチル、フタル酸ジブチル、フタル酸ジヘプチル、フタル酸ジ−２−エチルヘキシル、フタル酸ジイソオクチル、フタル酸ジ−ｎ−オクチル、フタル酸ジノニル、フタル酸ジイソノニル、フタル酸ジイソデシル、フタル酸ジウンデシル、フタル酸ジトリデシル、フタル酸ジシクロヘキシル、フタル酸ブチルベンジル、フタル酸ブチルラウリル、フタル酸メチルオレイル、フタル酸オクチルデシル、フマル酸ジブチル、フマル酸ジオクチルなどがある。
（ｃ）芳香族カルボン酸エステル系可塑剤
トリメリット酸トリオクチル、トリメリット酸トリ−ｎ−オクチル、オキシ安息香酸オクチルなどがある。
（ｄ）脂肪族二塩基酸エステル系可塑剤
アジピン酸ジブチル、アジピン酸ジ−ｎ−ヘキシル、アジピン酸ジ−２−エチルヘキシル、アジピン酸ジ−ｎ−オクチル、アジピン酸−ｎ−オクチル−ｎ−デシル、アジピン酸ジイソデシル、アジピン酸ジカプリル、アゼライン酸ジ−２−エチルヘキシル、セバシン酸ジメチル、セバシン酸ジエチル、セバシン酸ジブチル、セバシン酸ジ−ｎ−オクチル、セバシン酸ジ−２−エチルヘキシル、セバシン酸ジ−２−エトキシエチル、コハク酸ジオクチル、コハク酸ジイソデシル、テトラヒドロフタル酸ジオクチル、テトラヒドロフタル酸ジ−ｎ−オクチルなどがある。
（ｅ）脂肪酸エステル誘導体
オレイン酸ブチル、グリセリンモノオレイン酸エステル、アセチルリシノール酸メチル、ペンタエリスリトールエステル、ジペンタエリスリトールヘキサエステル、トリアセチン、トリブチリンなどがある。
（ｆ）オキシ酸エステル系可塑剤
アセチルリシノール酸メチル、アセチルリシノール酸ブチル、ブチルフタリルブチルグリコレート、アセチルクエン酸トリブチルなどがある。
（ｇ）エポキシ可塑剤
エポキシ化大豆油、エポキシ化アマニ油、エポキシステアリン酸ブチル、エポキシステアリン酸デシル、エポキシステアリン酸オクチル、エポキシステアリン酸ベンジル、エポキシヘキサヒドロフタル酸ジオクチル、エポキシヘキサヒドロフタル酸ジデシルなどがある。
（ｈ）二価アルコールエステル系可塑剤
ジエチレングリコールジベンゾエート、トリエチレングリコールジ−２−エチルブチラートなどがある。
（ｉ）含塩素可塑剤
塩素化パラフィン、塩素化ジフェニル、塩素化脂肪酸メチル、メトキシ塩素化脂肪酸メチルなどがある。
（ｊ）ポリエステル系可塑剤
ポリプロピレンアジペート、ポリプロピレンセバケート、ポリエステル、アセチル化ポリエステルなどがある。
（ｋ）スルホン酸誘導体
ｐ−トルエンスルホンアミド、ｏ−トルエンスルホンアミド、ｐ−トルエンスルホンエチルアミド、ｏ−トルエンスルホンエチルアミド、トルエンスルホン−Ｎ−エチルアミド、ｐ−トルエンスルホン−Ｎ−シクロヘキシルアミドなどがある。
（ｌ）クエン酸誘導体
クエン酸トリエチル、アセチルクエン酸トリエチル、クエン酸トリブチル、アセチルクエン酸トリブチル、アセチルクエン酸トリ−２−エチルヘキシル、アセチルクエン酸−ｎ−オクチルデシルなどがある。
（ｍ）その他
ターフェニル、部分水添ターフェニル、ショウノウ、２−ニトロジフェニル、ジノニルナフタリン、アビエチン酸メチルなどがある。
【０１７８】
各層に添加できる潤滑性物質としては、例えば下記のものが挙げられるがこれらに限定されるものではない。
（ａ）炭化水素系化合物
流動パラフィン、パラフィンワックス、マイクロワックス、低重合ポリエチレンなどがある。
（ｂ）脂肪酸系化合物
ラウリン酸、ミリスチン酸、パルチミン酸、ステアリン酸、アラキジン酸、ベヘン酸などがある。
（ｃ）脂肪酸アミド系化合物
ステアリルアミド、パルミチルアミド、オレインアミド、メチレンビスステアロアミド、エチレンビスステアロアミドなどがある。
（ｄ）エステル系化合物
脂肪酸の低級アルコールエステル、脂肪酸の多価アルコールエステル、脂肪酸ポリグリコールエステルなどがある。
（ｅ）アルコール系化合物
セチルアルコール、ステアリルアルコール、エチレングリコール、ポリエチレングリコール、ポリグリセロールなどがある。
（ｆ）金属石鹸
ステアリン酸鉛、ステアリン酸カドミウム、ステアリン酸バリウム、ステアリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムなどがある。
（ｇ）天然ワックス
カルナウバロウ、カンデリラロウ、蜜ロウ、鯨ロウ、イボタロウ、モンタンロウなどがある。
（ｈ）その他
シリコーン化合物、フッ素化合物などがある。
【０１７９】
各層に添加できる紫外線吸収剤として、例えば下記のものが挙げられるがこれらに限定されるものではない。
（ａ）ベンゾフェノン系
２−ヒドロキシベンゾフェノン、２，４−ジヒドロキシベンゾフェノン、２，２’，４−トリヒドロキシベンゾフェノン、２，２’，４，４’−テトラヒドロキシベンゾフェノン、２，２’−ジヒドロキシ４−メトキシベンゾフェノンなどがある。
（ｂ）サルシレート系
フェニルサルシレート、２，４−ジ−ｔ−ブチルフェニル３，５−ジ−ｔ−ブチル４ヒドロキシベンゾエートなどがある。
（ｃ）ベンゾトリアゾール系
（２’−ヒドロキシフェニル）ベンゾトリアゾール、（２’−ヒドロキシ５’−メチルフェニル）ベンゾトリアゾール、（２’−ヒドロキシ５’−メチルフェニル）ベンゾトリアゾール、（２’−ヒドロキシ３’−ターシャリブチル５’−メチルフェニル）５−クロロベンゾトリアゾールなどがある。
（ｄ）シアノアクリレート系
エチル−２−シアノ−３，３−ジフェニルアクリレート、メチル２−カルボメトキシ３（パラメトキシ）アクリレートなどがある。
（ｅ）クエンチャー（金属錯塩系）
ニッケル（２，２’チオビス（４−ｔ−オクチル）フェノレート）ノルマルブチルアミン、ニッケルジブチルジチオカルバメート、コバルトジシクロヘキシルジチオホスフェートなどがある。
（ｆ）ＨＡＬＳ（ヒンダードアミン）
ビス（２，２，６，６−テトラメチル−４−ピペリジル）セバケート、ビス（１，２，２，６，６−ペンタメチル−４−ピペリジル）セバケート、１−［２−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕エチル］−４−〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ〕−２，２，６，６−テトラメチルピリジン、８−ベンジル−７，７，９，９−テトラメチル−３−オクチル−１，３，８−トリアザスピロ〔４，５〕ウンデカン−２，４−ジオン、４−ベンゾイルオキシ−２，２，６，６−テトラメチルピペリジンなどがある。
【０１８０】
次に、図面を用いて本発明の画像形成装置全体を詳しく説明する。なお、以下に示す図や説明は本発明を説明するための一例であり、これに限定されるものではない。
【０１８１】
図９は、本発明の画像形成装置を説明するための概略図である。感光体１は本発明の感光体が用いられている。感光体１はドラム状の形状を示しているが、シート状、エンドレスベルト状のものであっても良い。
帯電部材３は、コロトロン、スコロトロン、固体帯電器（ソリッド・ステート・チャージャー）等による非接触帯電や帯電ローラーあるいは帯電ブラシによる接触帯電のいずれも使用することが可能である。さらに、帯電ローラー１６を用いる場合、図１０に示されるように感光体あるいは帯電ローラー１６にギャップを設けて、感光体と帯電ローラーとが画像形成領域１８において非接触となるように近接配置させることも可能であり有効である。特に、感光体表面に潤滑性物質を付着させた場合に、それらが帯電ローラーに付着することによって、帯電ローラーの汚染を促進させる場合がある。帯電ローラー１６の汚染は帯電ムラを引き起こしたり、感光体の汚染を促進させたりする恐れがある。従って、帯電ローラー１６と感光体１とが近接配置されていることによって、それらを抑制させる効果が得られる場合があるため有効である。感光体１に対し帯電部材１６が近接配置させる方法としては、感光体１の非画像形成領域にギャップを設ける必要があるが、それは例えば、ギャップ材１７を帯電部材に設けたり、感光体側に設けたり、あるいは感光体の両端にセットされるフランジ部に設けることによって形成することが可能であり、本発明においては感光体と帯電部材とが近接配置されていれば如何なる方法でも可能である。このようにギャップ材を使用する場合、ギャップ材１７は絶縁性である必要があり、耐摩耗性の高い材料が有効に用いられる。ギャップ材はテープ状、シール状もしくはチューブ状等、如何なる形態のものでも使用できる。ギャップの厚さは、１０〜２００μｍが好ましく、２０〜１００μｍがより好ましく、さらに好ましくは４０〜８０μｍである。ギャップがこれよりも小さい場合には、帯電部材と感光体の接触が多くなり、近接配置させたメリットが得られず画質劣化の影響が増加し、ギャップがこれよりも大きい場合には帯電の安定性が低下し帯電ムラが発生する場合がある。また、帯電部材には直流成分に交流成分を重畳して感光体に帯電を付与することが可能である。交流成分を重畳することによって、帯電ムラを低減することが可能となり、それによって画像濃度ムラやコントラストの低下を抑制することが可能となり有用である。
コロトロンやスコロトロンによるコロナ帯電方式は、感光体表面への放電生成物の付着量は比較的少ない傾向にあるものの、オゾン発生量は非常に多くなる傾向にある。一方、帯電ローラーを用いた場合にはオゾン発生量は軽減できるものの、放電生成物の付着量が増加する傾向にある。オゾンも放電生成物も画像流れ等に大きな影響を及ぼす因子であるが、本発明は放電生成物の付着による画像流れに対する抑制手段であるため、帯電手段に帯電ローラーを用いた場合にその効果がより発揮されることになる。
【０１８２】
次に、均一に帯電された感光体上に静電潜像を形成するために画像露光部５が用いられる。この光源には、蛍光灯、タングステンランプ、ハロゲンランプ、水銀灯、ナトリウム灯、発光ダイオード（ＬＥＤ）、半導体レーザー（ＬＤ）、エレクトロルミネッセンス（ＥＬ）などの発光物全般を用いることができる。そして、所望の波長域の光のみを照射するために、シャープカットフィルター、バンドパスフィルター、近赤外カットフィルター、ダイクロイックフィルター、干渉フィルター、色温度変換フィルターなどの各種フィルターを用いることもできる。
【０１８３】
次に、感光体上に形成された静電潜像を可視化するために現像ユニット６が用いられる。現像方式としては、乾式トナーを用いた一成分現像法、二成分現像法、湿式トナーを用いた湿式現像法等がある。感光体に正（負）帯電を施し、画像露光を行うと、感光体表面上には正（負）の静電潜像が形成される。これを負（正）極性のトナー（検電微粒子）で現像すれば、ポジ画像が得られるし、また正（負）極性のトナーで現像すれば、ネガ画像が得られる。
【０１８４】
フルカラー用電子写真装置における現像ユニット６は、少なくともイエロー、マゼンタ、シアン、ブラックの４色に対応したユニットを有しており、１つの感光体に４色の現像ユニットが近接された方式や、１つの現像ユニットに４色のトナーが分別されて充填され、ユニット自体が４段階に回転することによって４色の現像を順次行う、リボルバー方式や、４色のトナーが充填された各々４つのユニットに対し４つの感光体が配置された図１２に示すタンデム方式等が挙げられる。
【０１８５】
トナーの作製は、粉砕あるいは重合による方法が一般的となっているが、近年重合による方法が用いられるようになってきている。重合によって球形の形状のトナーが得られやすいことが知られているが、トナーが球形あるいは略球形の形状を有することによって離型性が向上するため、転写時に感光体に残存するトナーが少なく、転写効率の向上及び中抜け等の異常画像の抑制が実現できる。しかし、球形あるいは略球形トナーはクリーニング性を著しく低下させるため、従来は球形あるいは略球形の形状を避けて作らざるを得ず、それによって十分な転写効率が得られていないのが実情であった。本発明は感光体に交差する線状傷を形成したことにより、転写効率に対しては離型性向上によってさらなる効果を与えると共に、クリーニング性を大幅に向上させることが可能である。感光体表面に形成される線状傷が一方向の場合で、特にそれが感光体の周方向に形成されていた場合には、球形あるいは略球形トナーは転がりやすくクリーニング性を大幅に低下させることになるが、本発明では線状傷が交差して形成されていることから、トナーの動きを抑えることが可能となり、またクリーニングブレードと感光体との接触面積が減少したことにより、クリーニングブレードの過剰な摩擦を低減できたことによりクリーニング性の向上が可能となった。
【０１８６】
次に、感光体上で可視化されたトナー像は紙上、もしくは中間転写体に転写される。図１１は、本発明における感光体１に中間転写ベルト２０が接触し、感光体と紙とが直接接触しない構成を有する画像形成装置を説明するための概略図である。なお、中間転写体はドラム状であっても、シート状あるいはエンドレスベルト状であってもよい。中間転写体もしくは中間転写ベルト２０上に形成されたトナー像は、直ちに紙９に転写される。これらの転写手段としても、転写チャージャー、バイアスローラーを用いる静電転写方式、粘着転写法、圧力転写法等の機械転写方式、磁気転写方式等、従来の方式が利用可能である。
【０１８７】
感光体からトナーが転写されるとき、感光体の離型性が低いと、トナーが感光体に残存してしまい、中抜けの原因となったり、転写効率の低下による画質劣化の原因となる。本発明においては、感光体表面の離型性を向上させる効果も得られたことから、転写効率の向上並びに中抜けの抑制をも同時に改善することが可能となった。また、感光体に中間転写ベルトが接触し、感光体と紙とが直接接触しない構成を有することによって、感光体表面の紙粉付着を抑制する効果が得られるため、本発明においてはより好ましい。感光体表面への放電生成物やトナー外添剤の付着は、紙粉を引き寄せるため、フィルミングが促進される場合があるが、中間転写ベルトを用いて感光体と紙とが直接接触していないことによって、その影響を大幅に抑制することが可能となる。
【０１８８】
また、図１２にはタンデム方式でかつ中間転写ベルト２０が具備された画像形成装置の概略図を示す。上記タンデム方式の画像形成装置において、各感光体上に形成されたトナー像を中間転写体もしくは中間転写ベルト２０等に一次転写を行い、その後転写体（紙）９に二次転写を行うことによって、各感光体と紙９とが直接接触しない構成とすることは前記のとおり高耐久化、高画質化に対し非常に有効である。特に、タンデム方式の画像形成装置のおいては、感光体間における経時劣化変動を可能な限り少なくする必要があり、感光体表面の摩耗量はもちろん、感光体表面への汚染の影響に感光体間で大きな差が生じてくると、４本の感光体により一つの画像を形成する機構上、色再現性や解像度低下等、画像劣化を引き起こすことになる。特に、中抜けが起こると色再現性が低下することにもなり、カラー画像の場合その画質劣化の影響は非常に大きくなる。また、タンデム方式の場合には、感光体表面の汚染物質である放電生成物、トナー外添剤、紙粉の中でも紙粉による影響の度合いが大きい傾向にある。それは、少なくとも４色の転写が終わるまで各感光体は紙と接触している必要があることや、印刷する色の種類によって各色のトナー使用量に差が生じてくるのに対し、トナー使用量に関わらず感光体は絶えず紙と接触している必要があることによる。例えば、ブラックのみの印刷を行う場合には、ブラック以外の３つの感光体は紙に接触しないようにする機構などが考えられてはいるものの、実際には単色のみによる印刷需要は少なく、紙粉による影響が大きくなるのが一般的となっている。これらのことから、タンデム方式の画像形成装置において、感光体上のトナー像を中間転写体もしくは中間転写ベルトに一次転写させることによって、感光体と紙とが直接接触しない構成とした場合、本発明の感光体を用いることにより、感光体の高耐久化だけでなく、画像ボケやフィルミングの抑制、色再現性や解像度の向上等に特に有効となる。
【０１８９】
次に、転写後感光体上に残されたトナーをクリーニングするために、ファーブラシやクリーニングブレードあるいはそれらを併用して用いられるが、本発明においては、感光体表面に残存したトナーだけをクリーニングするのではなく、感光体に付着した放電生成物をも除去する必要があるため、特にクリーニング手段にはクリーニングブレードが好適に用いられる。感光体表面に交差する線状傷を形成したことによって、感光体とクリーニングブレードとの接触面積を減少させ、それによって過剰な摩擦を抑え、クリーニング性を向上させることが可能となる。また、線状傷に放電生成物が入り込み、放電生成物の残存する箇所を区別できたことにより、画像流れの影響を抑制できたと同時に、感光体表面に付着した放電生成物のクリーニング性が向上し、これにより画質の向上並びにその安定性を高めることが可能となる。
【０１９０】
滑り性を付与するために、感光体表面に滑性成分を含む化合物を付着させることも可能である。それによって、感光体の離型性を高めたり、耐摩耗性を高めたり、異物付着を抑制したりする上で非常に有効である。特に、放電生成物のクリーニングに対しても有効であり、本発明の感光体と組み合わせることにより相乗効果を得ることが可能となる。保護層に含有される滑り性を付与する化合物としては、添加することによって滑り性が付与されれば、いかなる材料を用いてもよいが、特にシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物が有効に用いられる。シリコーン系化合物とは、分子構造にＳｉを含有するものであればいかなるものでも含まれ、例えばシリコーン樹脂並びに樹脂微粒子などが挙げられる。フッ素系化合物とは、分子構造にＦを含んでいるものであればいかなるものでも含まれ、ＰＴＦＥ・ＰＦＡ・ＰＶＤＦ等の各種フッ素樹脂微粒子等が挙げられる。また、長鎖アルキル基含有化合物としては、長鎖アルキル基を含有する材料であればいかなるものでも含まれ、特にステアリン酸亜鉛は有効に用いられる。その他、ポリオレフィン系樹脂、シリコングリース、フッ素グリース、パラフィンワックス、脂肪酸エステル類、黒鉛、二硫化モリブデン等が挙げられる。感光体表面にこれらの滑り性を付与する化合物を付着させることによって、感光体に離型性を与える効果の持続性が著しく向上されたものの、その付着量を制御することが難しく、過剰に付着するとフィルミングを助長したり、異常画像や偏摩耗を引き起こす原因となっていた。本発明においては、感光体表面に交差する線状傷を形成したことにより、これらの滑性成分を含む化合物がその傷に入り込むことによって、感光体表面に付与される滑り性の効果の持続性が高まり、それによって少ない付着量でも十分な効果が得られたことにより感光体表面の汚染を抑制することが可能となり、異常画像の発生や偏摩耗を抑制することが可能となる。
【０１９１】
これらの滑性成分を含む化合物を感光体表面に付着させる手段としては、いかなる方法でも使用することができるが、具体的には感光体表面にこれら化合物の固形物を直接接触させる方法や感光体にブラシを接触させ、ブラシを介して付着させる方法あるいは現像剤にこれらの化合物を混合して付着させる方法などが挙げられる。
【０１９２】
本発明における感光体表面に形成される線状傷は、感光体未使用時に形成されていることが好ましいが、感光体の使用経時で摩耗の影響が生じるため、使用経時でも線状傷を形成させることがより効果的であり、それによって耐摩耗性と画質安定化の両立が可能となり、感光体の寿命を大きく向上させることが実現できる。そのため、画像形成装置内に感光体表面に線状傷を形成する手段を含むことが好ましい。
【０１９３】
本発明の感光体表面に交差する線状傷を形成させる手段を含む画像形成装置については、いかなる手段を用いることも可能であるが、画像形成装置の使用経時で感光体に研磨物を押し当て擦る手段が特に有効である。研磨物を感光体に接触させて、感光体の軸方向に往復運動させたり、感光体を回転させたり、あるいはそれらを同時に動かすことによって、いかなる方向に対しても線状傷を形成することができる。また、感光体の使用経時で主に現像剤とクリーニングブレードとによって形成される感光体の傷についても、本発明の線状傷に含まれる。但し、感光体に形成される傷はそのほとんどが感光体の周方向への一方向の傷であるため、上記手段はその傷とは交差する方向にさらに線状傷を形成させる必要があり、好ましくはその傷に対し４５〜１３５度の範囲で交差させることが有効である。それによって、あらゆる方向のラインに対しても画像流れを抑制することが可能となる。また、上記研磨物を感光体に押し当て擦ることによって線状傷が形成されるが、それと同時に感光体表面に付着したフィルミング物を除去できる効果も発揮され、画質安定化に対しさらなる効果を得ることができる。研磨物を押し当て擦ることにより、感光体の耐摩耗性が低下するが、この動作は常時行う必要はないため感光体の耐摩耗性に与える影響は大きくはない。
【０１９４】
次に、必要に応じて感光体上の潜像を取り除く目的で除電手段が用いられる。除電手段としては除電ランプ、除電チャージャーが用いられ、それぞれ上記露光光源、帯電手段を利用できる。
その他、感光体に近接していない原稿読み取り、給紙、定着、排紙等のプロセスは従来公知のものが全て使用できる。
【０１９５】
以上の図示した画像形成プロセスは、本発明における実施形態を例示するものであって、もちろん他の実施形態も可能である。例えば、光照射工程は、像露光、クリーニング前露光、除電露光が図示されているが、他に転写前露光、像露光のプレ露光、及びその他公知の光照射工程を設けて、感光体に光照射を行うこともできる。
【０１９６】
これらの画像形成手段は、複写装置、ファクシミリ、プリンター内に固定して組み込まれていてもよいが、プロセスカートリッジの形態でそれらの装置内に組み込まれ、着脱自在の構成としたものであってもよい。図１３は、電子写真装置用プロセスカートリッジの一例を示す概略図である。本発明における画像形成装置用プロセスカートリッジとは、感光体及びクリーニング手段を内蔵し、他に帯電手段、現像手段、転写手段、除電手段の少なくとも一つを一体化し、画像形成装置本体に対して着脱可能とした部品である。本発明には、前記感光体が画像形成装置本体に対して着脱自在の構成を有するプロセスカートリッジに内蔵され、かつ前記プロセスカートリッジがタンデム方式の画像形成装置に内蔵された画像形成装置や、プロセスカートリッジに内蔵された前記感光体が転写工程において直接紙と接触しない構成を有する画像形成装置、及びそれらを組み合わせた画像形成装置、並びにそれらのプロセスカートリッジがすべて含まれる。
【０１９７】
【実施例】
以下、本発明について実施例を挙げて説明するが、本発明が実施例により制約を受けるものではない。なお、部はすべて重量部である。
【０１９８】
感光体製造例１
アルミニウムシリンダー上に下記組成の下引き層塗工液、電荷発生層塗工液、及び電荷輸送層塗工液を、浸漬塗工によって順次塗布、乾燥し、約３．０μｍの下引き層、約０．２μｍの電荷発生層、約２０μｍの電荷輸送層を形成した。さらに、その上に下記組成の保護層塗工液を用いて約５μｍの保護層を積層し、電子写真感光体１を作製した。
下引き層塗工液
下引き層塗工液の構成成分比を下記に示す。
アルキッド樹脂
（ベッコゾール１３０７−６０大日本インキ化学工業製）： ６部
メラミン樹脂
（スーパーベッカミンＧ−８２１−６０大日本インキ化学工業）：４部
酸化チタン粉末
（「タイペールＣＲ−ＥＬ」石原産業社製）： ４０部
メチルエチルケトン： ５０部
電荷発生層塗工液
電荷発生層塗工液の構成成分比を下記に示す。
下記構造式（１）の非対称ビスアゾ顔料： ２．５部
【化４９】

ポリビニルブチラール（「ＸＹＨＬ」ＵＣＣ製）： ０．５部
メチルエチルケトン： ８０部
シクロヘキサノン： ２００部
電荷輸送層塗工液
電荷輸送層塗工液の構成成分比を下記に示す。
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製）： １０部
下記構造式（２）の電荷輸送物質： １０部
【化５０】

シリコーンオイル（「ＫＦ５０」信越化学製）： ０．００２部
テトラヒドロフラン： １２０部
保護層塗工液
保護層塗工液の構成成分比を下記に示す。
アルミナ（平均一次粒径：０．３μｍ、住友化学工業製）： ２．０部
不飽和ポリカルボン酸ポリマー溶液（酸価１８０ｍｇＫＯＨ／ｇ、不揮発分５０％「ＢＹＫ−Ｐ１０４」ＢＹＫケミー製）： ０．０６部
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製） １０部
上記構造式（２）の電荷輸送物質： ８部
テトラヒドロフラン： ４７０部
シクロヘキサノン： ２００部
【０１９９】
感光体製造例２
感光体製造例１において、保護層塗工液を下記組成の保護層塗工液に変更した以外は、すべて感光体製造例１と同様にして電子写真感光体２を作製した。
［保護層塗工液］
アルミナ（平均一次粒径：０．３μｍ、住友化学工業製）： ５．０部
不飽和ポリカルボン酸ポリマー溶液（酸価１８０ｍｇＫＯＨ／ｇ、不揮発分５０％「ＢＹＫ−Ｐ１０４」ＢＹＫケミー製）： ０．０６部
ポリアリレート（Ｕ−６０００、ユニチカ製）： １０部
上記構造式（２）の電荷輸送物質： ８部
テトラヒドロフラン： ５２０部
シクロヘキサノン： ２３０部
【０２００】
感光体製造例３
感光体製造例１において、保護層塗工液を下記の組成に変更した以外は、すべて感光体製造例１と同様にして電子写真感光体３を作製した。
保護層塗工液
シリコーン樹脂微粒子
（平均一次粒径：０，５μｍ、東芝シリコーン製）： ４０部
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製）： １０部
上記構造式（２）の電荷輸送物質： ７部
テトラヒドロフラン： ４７０部
シクロヘキサノン： ２００部
【０２０１】
感光体製造例４
感光体製造例１において、保護層塗工液を下記の組成に変更した以外は、すべて感光体製造例１と同様にして電子写真感光体４を作製した。
保護層塗工液
シリカ（平均一次粒径：０．１μｍ、信越化学製）： ３．５部
アクリル樹脂（水酸基価２５（ｍｇＫＯＨ／ｇ）、不揮発分５０％、日立化成製）： １４部
グアナミン樹脂（不揮発分７０％、三井サイテック製）： ４．５部
芳香族スルホン酸（不揮発分４０％、三井サイテック製）：０．０２部
上記構造式（２）の電荷輸送物質： ７部
テトラヒドロフラン： ４５０部
シクロヘキサノン： ２００部
【０２０２】
感光体製造例５
感光体製造例１において、保護層塗工液を下記の組成に変更した以外は、すべて感光体製造例１と同様にして電子写真感光体５を作製した。
保護層塗工液
アルミナ
（平均一次粒径：０，３μｍ、ＡＡ−０３住友化学工業製）：３．０部
不飽和ポリカルボン酸ポリマー（酸価１８０ｍｇＫＯＨ／ｇ、不揮発分５０％「ＢＹＫ−Ｐ１０４」ＢＹＫケミー製）： ０．０９部
下記構造式の高分子電荷輸送物質： １５部
【０２０３】
【化５１】

テトラヒドロフラン： ５００部
シクロヘキサノン： ２００部
【０２０４】
感光体製造例６
感光体製造例１において、保護層塗工液を下記の組成に変更した以外は、すべて感光体製造例１と同様にして電子写真感光体６を作製した。
保護層塗工液
アルミナ（平均一次粒径：０．３μｍ、住友化学工業製）： ３．５部
不飽和ポリカルボン酸ポリマー（酸価１８０ｍｇＫＯＨ／ｇ、不揮発分５０％「ＢＹＫ−Ｐ１０４」ＢＹＫケミー製）： ０．０６部
フッ素樹脂微粒子（平均一次粒径：１μｍ、シャムロック製）：２．０部
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製） １０部
上記構造式（２）の電荷輸送物質： ７部
テトラヒドロフラン： ５００部
シクロヘキサノン： ２２０部
【０２０５】
感光体製造例７
感光体製造例１において、電荷発生層塗工液、電荷輸送層塗工液及び保護層塗工液を下記のものに変更した以外は、感光体製造例１と同様にして、電子写真感光体７を作製した。
電荷発生層塗工液
ポリビニルブチラール
（「エスレックＢＸ−１」積水化学工業製）： ５部
メチルエチルケトン： ４００部
図１４に示したＸＤスペクトルを有するチタニルフタロシアニン： ８部
電荷輸送層塗工液
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製）： １０部
上記構造式（２）の電荷輸送物質： １０部
シリコーンオイル（「ＫＦ５０」信越化学製）： ０．００２部
テトラヒドロフラン： １２０部
保護層塗工液
アルミナ
（平均一次粒径：０．３μｍ、ＡＡ−０３住友化学工業製） ：４．０部
不飽和ポリカルボン酸ポリマー（酸価１８０ｍｇＫＯＨ／ｇ、不揮発分５０％「ＢＹＫ−Ｐ１０４」ＢＹＫケミー製）： ０．０８部
ビスフェノールＺポリカーボネート
（パンライトＴＳ−２０５０、帝人化成製）： １０部
上記構造式（２）の電荷輸送物質： １０部
テトラヒドロフラン： ５４０部
シクロヘキサノン： ２３０部
【０２０６】
感光体製造例８
感光体製造例１において、電荷輸送層の膜厚を約２５μｍとし、その上に保護層を形成しなかった以外はすべて感光体製造例１と同様にして、電子写真感光体８を作製した。
【０２０７】
実施例１
電子写真感光体１をプラスチック製のラッピングフィルムシート（粒度１５μｍ、３Ｍ製）を用いて、図７に示すような交差する線状傷を形成した。線状傷の幅は平均３．５μｍ、線状傷間の間隔は最大２０μｍ、線状傷の交差角度は６０〜１２０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２０８】
実施例２
電子写真感光体２をプラスチック製のラッピングフィルムシート（粒度１５μｍ、３Ｍ製）を用いて、図８に示すような交差する線状傷を形成した。線状傷の幅は平均３．５μｍ、線状傷間の間隔は最大１０μｍ、線状傷の交差角度は３０〜６０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２０９】
実施例３
電子写真感光体３をサンドペーパー（＃１０００）を用いて、図６に示すような交差する線状傷を形成した。線状傷の幅は平均３μｍ、線状傷間の間隔は最大１５μｍ、線状傷の交差角度は９０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２１０】
実施例４
電子写真感光体４において、保護層を形成した後、直ちに微細な凹凸形状を有する金型に接触させ、感光体表面に図７に示される形状を有する線状傷を交差させて形成した。線状傷の幅は平均５μｍ、線状傷間の間隔は最大３０μｍ、線状傷の交差角度は９０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２１１】
実施例５
電子写真感光体６を回転ブラシに接触させて、図６に示すような交差する線状傷を形成した。線状傷の幅は平均４μｍ、線状傷間の間隔は最大４０μｍ、線状傷の交差角度は約９０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２１２】
実施例６
電子写真感光体７を研磨用砥石に接触させ、図６に示すような交差する線状傷を形成した。線状傷の幅は平均５μｍ、線状傷間の間隔は最大３０μｍ、線状傷の交差角度は約９０度であることを感光体のレーザー顕微鏡観察によって確認した。
【０２１３】
以上のように作製した実施例１〜６の電子写真感光体を、電子写真装置用プロセスカートリッジに装着し、画像露光光源の波長が６５５ｎｍ（但し、電子写真感光体７のみ７８０ｎｍ）の半導体レーザーを用い、帯電ローラー及びクリーニングブレードを装着した（株）リコー製デジタル複写機改造機にて、画像出力を行った。なお、トナーは非球形状で粒径が約８μｍのものを使用した。
次に現像及びクリーニングブレードを除去したプロセスカートリッジに感光体を移し、転写もはずして帯電のみでのフリーランを３０℃９０％ＲＨの環境下で３０分実施した。その後通常のプロセスカートリッジに戻し画像出力を行った。さらに、上記実施例１〜６の電子写真感光体について常温常湿（２５℃６０％ＲＨ）環境下においてそれぞれ５万枚の通紙ランを行い、ラン前後の膜厚差から摩耗量を求めた。なお、図１５あるいは図１６に示す方法を用いて１万枚毎に感光体の軸方向に線状傷を形成した。５万枚印刷後、感光体を３０℃９０％ＲＨの環境下に移し画像出力を行った。画像ランクは以下の記号によって区別した。
◎：画像流れが認められず良好な画像
○：画像流れは認められるが、品質上問題ないレベル
△：画像流れが明らかにわかり文字が読みにくく、ドットの散りも目立つレベル
×：画像流れによってドットが完全に散っており、文字も判読できないレベル
【０２１４】
【表１】

【０２１５】
比較例１
電子写真感光体１に線状傷をまったく形成しなかった。
【０２１６】
比較例２
電子写真感光体２をプラスチック製のラッピングフィルムシート（粒度１５μｍ、３Ｍ製）を用いて、感光体の周方向のみに線状傷を形成し傷を交差させなかった。線状傷の幅は平均３．５μｍ、線状傷間の間隔は最大２０μｍであることを感光体のレーザー顕微鏡観察によって確認した。
【０２１７】
比較例３
電子写真感光体３をプラスチック製のラッピングフィルム（粒度１５μｍ、３Ｍ製）を用いて、感光体の周方向のみに線状傷を形成し傷を交差させなかった。線状傷の幅は平均３．５μｍ、線状傷間の間隔は最大２０μｍであることを感光体のレーザー顕微鏡観察によって確認した。
【０２１８】
比較例４
電子写真感光体４をサンドペーパー（＃２０００）を用いて、感光体の軸方向のみに線状傷を形成し傷を交差させなかった。線状傷の幅は平均２．５μｍ、線状傷間の間隔は最大１０μｍであることを感光体のレーザー顕微鏡観察によって確認した。
【０２１９】
比較例５
電子写真感光体５を回転ブラシに接触させて、感光体の周方向のみに線状傷を形成し傷を交差させなかった。線状傷の幅は平均４μｍ、線状傷間の間隔は最大４０μｍであることを感光体のレーザー顕微鏡観察によって確認した。
【０２２０】
比較例６
電子写真感光体７に線状傷をまったく形成しなかった。
【０２２１】
以上のように作製した比較例１〜６の電子写真感光体を、電子写真装置用プロセスカートリッジに装着し、画像露光光源の波長が６５５ｎｍ（但し、電子写真感光体８のみ７８０ｎｍ）の半導体レーザーを用い、帯電ローラー及びクリーニングブレードを装着した（株）リコー製デジタル複写機改造機にて、画像出力を行った。なお、トナーは非球形状で粒径が約８μｍのものを使用した。
次に現像及びクリーニングを除去したプロセスカートリッジに感光体を移し、転写もはずして帯電のみでのフリーランを３０℃９０％ＲＨの環境下で３０分実施した。その後通常のプロセスカートリッジに戻し画像出力を行った。さらに、上記比較例１〜６の電子写真感光体について常温常湿（２５℃６０％ＲＨ）環境下においてそれぞれ５万枚の通紙ランを行い、ラン前後の膜厚差から摩耗量を求めた。なお、通紙ラン経時で線状傷の形成は行わなかった。５万枚印刷後、感光体を３０℃９０％ＲＨの環境下に移し、画像出力を行った。
画像ランクは以下の記号によって区別した。
◎：画像流れが認められず良好な画像
○：画像流れは認められるが、品質上問題ないレベル
△：画像流れが明らかにわかり文字が読みにくく、ドットの散りも目立つレベル
×：画像流れによってドットが完全に散っており、文字も判読できないレベル
【０２２２】
【表２】

【０２２３】
表１及び表２の結果より、感光体の保護層表面に交差する線状傷を形成した後、高温高湿下帯電のみのフリーランを実施し強制的に一定量の放電生成物を付着させても、画像流れは抑制されることが確認できた。帯電のみのフリーランによって一部画質が低下していても、出力枚数の増加によって即時に回復性が認められ、傷に放電生成物が閉じ込められ画像流れの影響が軽減されていることがわかる。
また、全体的に耐摩耗性が高くなるに従い、画像流れの影響が増加する傾向に見られるが、耐摩耗性が高くても高分子電荷輸送物質を用いたり、感光体の最表面層に潤滑性を有する材料を添加することによって、効果が高くなる傾向が見られている。一方、感光体表面に交差する線状傷を形成しなかったり、線状傷を形成しても交差させなかったりした場合には、画像流れ抑制効果が得られておらず、たとえ潤滑性物質を添加してもその効果は十分ではなかった。これらの傾向は、長期に渡る通紙ランの結果にも反映されており、これによって耐摩耗性と画像流れ抑制が両立された。
【０２２４】
次に、作製した実施例１〜６及び比較例１〜６の電子写真感光体を、電子写真装置用プロセスカートリッジに装着し、画像露光光源の波長が６５５ｎｍの半導体レーザーを用い、図１２に示す帯電方式及びクリーニングブレードを装着し、さらに略球形トナーを用いた（株）リコー製フルカラープリンタ改造機にて、画像出力を行い、経時における画像評価を行った。略球形トナーの粒径は約６μｍであった。
画像ランクは以下の記号によって区別した。
◎：画像欠陥が一切なく良好な画像
○：画像品質上問題ないレベル
△：画像欠陥が確認されるが、判読可能なレベル
×：画像欠陥が多発し、判読不可能なレベル
【０２２５】
【表３】

【０２２６】
表３の結果より、球形もしくは略球形トナーを用いた場合には、クリーニング不良によりスジ状の画像欠陥が発生する傾向が認められた。感光体の軸方向に線状傷を形成したり、感光体の表面に潤滑性物質を添加することにより若干抑制できるものの、効果としては不十分であった。しかし、本発明の交差する線状傷を感光体の表面に形成することによって、クリーニング不良に伴うスジ状の画像欠陥を抑制することが可能となり、球形もしくは略球形トナーを使いこなすことが可能となった。
【０２２７】
【発明の効果】
以上説明したように、請求項１によれば、少なくとも帯電、露光、現像、転写及びクリーニングの工程が順次繰り返されることによって画像形成を行う画像形成装置に使用される電子写真感光体において、前記電子写真感光体の表面にフィラーを含有した保護層が積層され、かつ該保護層の表面に互いに交差する無数の線状傷が連続的に形成されていることを特徴とする電子写真感光体により、電子写真感光体の保護層にフィラーを含有し、かつその表面に交差する線状傷を形成することによって、感光体の耐摩耗性の向上と同時に、放電生成物が感光体の表面に付着しても画像流れを抑制することが可能となった。感光体の表面に形成される線状傷が少なくとも２方向より交差させることによって、あらゆる角度を有する書き込みラインに対しても像流れ抑制効果を得ることが可能となった。これにより感光体の耐摩耗性の向上と画像流れの抑制を両立することが可能となった。
【０２２８】
請求項２によれば、前記線状傷の幅が、トナー粒子の粒径よりも小さいことを特徴とする請求項１に記載の電子写真感光体により、電荷の拡散領域を十分に小さくすることができ、それによって画像流れの抑制効果が高くなった。また、傷にトナーが入り込まないことによって画像欠陥を防止する効果も有し、それによって高画質化を実現することが可能となる。
【０２２９】
請求項３によれば、前記線状傷の交差角度が、４５〜１３５度の範囲内にあることを特徴とする請求項１又は２に記載の電子写真感光体により、交差する線状傷の交差角度が小さい場合には、線状傷を交差させたことによる効果が低減し、書き込んだラインの角度によって画像流れ抑制効果が減少し、十分な抑制効果が得られないが、少なくとも交差角度を４５〜１４５度の範囲内になるように形成することによって、あらゆる方向のラインやドットに対しても画像流れを抑制することが可能となり、画像流れ抑制効果を十分に得ることが可能となる。
【０２３０】
請求項４によれば、前記線状傷間の間隔が、５０μｍ以下であることを特徴とする請求項１から３のいずれか１項に記載の電子写真感光体によれば、感光体表面に形成される線状傷間の間隔が大きすぎたり、間隔が不均一であったり、感光体表面上に線状傷の領域が少なくなると放電生成物の閉じ込め効果が減少したりムラが発生し、画像流れの影響が増加するのに対し、線状傷間の間隔を少なくとも５０μｍ以下にすることにより、画像流れの抑制効果にムラがなく、十分な効果を得ることが可能となる。
【０２３１】
請求項５によれば、前記フィラーが、金属酸化物であることを特徴とする請求項１に記載の電子写真感光体によれば、フィラーが金属酸化物であることによって、感光体の耐摩耗性の向上に特に有効となる。また、本発明においてはくり返し使用によって現像剤やクリーニングブレード等から感光体表面に形成される傷も線状であって、本発明の線状傷として扱うこともできる。この場合、金属酸化物は硬度が高く、研磨性を有するものが多いため、感光体の耐摩耗性を高める効果だけでなく、感光体の最表面に線状傷を形成させる上でも有効である。特に、これらの金属酸化物を感光体表面に含有させたことにより形成される線状傷の形状は、傷の幅が狭いなど、画像流れの抑制効果を高めることが可能となる。
【０２３２】
請求項６によれば、前記フィラーの金属酸化物がアルミナであることを特徴とする請求項１又は５に記載の電子写真感光体によれば、金属酸化物にアルミナを用いることによって、オゾンやＮＯｘによる画像流れや高温高湿環境下における画像ボケを抑制することが可能となる。アルミナを保護層に含有し、かつその表面に交差する線状傷を形成することにより、さらに帯電生成物の付着による画像流れを抑制することが可能となり、これにより感光体の耐摩耗性の向上と同時に、多くの画像欠陥を抑制することが可能となる。
【０２３３】
請求項７によれば、前記フィラーの平均一次粒径が、０．０１〜３．０μｍであることを特徴とする請求項１、５、６のいずれか１項に記載の電子写真感光体によれば、フィラーの平均一次粒径が非常に大きいと、画質劣化を引き起こし、本発明の効果が半減する恐れがある。また、感光体表面に形成される線状傷の幅が非常に大きくなり、それによって電荷の拡散領域が広がって画像流れの抑制効果が低下する。フィラーの平均一次粒径を０．０１〜３．０μｍの範囲にすることにより、画質劣化が抑制され、感光体表面に形成される線状傷の幅も狭くすることが可能となり、それによって画像流れの抑制効果を高めることが可能となる。
【０２３４】
請求項８によれば、前記保護層に含有されるバインダー樹脂が、ポリカーボネート樹脂あるいはポリアリレート樹脂、アクリル系もしくはメタクリル系樹脂のいずれかであることを特徴とする請求項１に記載の電子写真感光体によれば、保護層に含有されるバインダー樹脂によって、感光体の耐摩耗性が変わるだけでなく、感光体表面に形成される線状傷の幅も変化し、それは画像流れ抑制効果に大きく影響する。バインダー樹脂に少なくともポリカーボネート樹脂あるいはポリアリレート樹脂、アクリル系もしくはメタクリル系樹脂を用いることによって、画像流れ抑制効果を十分に発揮させることが可能となる。
【０２３５】
請求項９によれば、前記保護層に含有されるバインダー樹脂が、高分子電荷輸送物質であることを特徴とする請求項１に記載の電子写真感光体によれば、バインダー樹脂とともに電荷の移動のために電荷輸送物質を含有することによって露光部電位の安定化が図られ、画像品質の安定化が実現されるが、バインダー樹脂として電荷輸送機能とバインダー機能とを併せ持つ高分子電荷輸送物質を用いることによって、感光体の耐摩耗性のさらなる向上が実現できると同時に、感光体表面に形成される線状傷の幅を狭くすることが可能となる。それにより、画像流れ抑制効果を向上させることが可能となる。
【０２３６】
請求項１０によれば、前記バインダー樹脂が、熱硬化性樹脂あるいは光硬化性樹脂であることを特徴とする請求項１、８、９のいずれか１項に記載の電子写真感光体により、バインダー樹脂を硬化して用いることにより、感光体の耐摩耗性をさらに高めることが可能となり、本発明の効果をより一層発揮させるに適している。また、硬化性樹脂をバインダー樹脂として用いることにより、感光体の最表面層の塗工後に交差する無数の線状傷を形成し、その後硬化させるなど、線状傷を形成しその効果の安定化を実現する上で非常に有効な手段となることが可能となる。
【０２３７】
請求項１１によれば、前記保護層に、さらにシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物の少なくとも１種が含有されていることを特徴とする請求項１又は８から１０のいずれか１項に記載の電子写真感光体により、保護層にシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物の少なくとも１種を含有させると、感光体表面の摩擦係数が低減し、放電生成物のクリーニング性が向上することにより除去しやすくなる効果が得られる。表面が粗面化され離型性が向上したことによる効果と相まって、画像流れ抑制効果がさらに高めることが可能となる。また、これらの化合物を感光体表面に含有させても、従来は摩擦係数低減効果の持続性に非常に乏しいものであったが、本発明においては保護層に交差する線状傷が形成されていることにより、摩擦係数低減効果の持続性を高めることが可能となる。また、放電生成物は摩擦係数を上昇させる原因でもあるため、それらを線状傷内に閉じ込めることによって、摩擦係数低減効果の持続性が大幅に高まり、多くの相乗効果を得られることにより、高画質化並びにその安定化に対し大きな効果を得ることが可能となる。
【０２３８】
請求項１２によれば、前記シリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物が、微粒子の形状を有しており、且つ前記保護層に分散されてなることを特徴とする請求項１１に記載の電子写真感光体によれば、従来の電子写真感光体の表面に、シリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物等のような潤滑性物質を微粒子として含有させ、画像形成装置内に感光体表面に線状傷を形成する手段を含む場合、感光体表面に線状傷を形成する工程において、シリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物が微粒子の形状を有し、且つ感光体の最表面層に分散されていることにより、感光体表面にこれらの化合物の供給性が向上し、摩擦係数の持続性を著しく高めることが可能となる。それによって、画像流れ抑制効果をより一層高めると同時に、フィルミングや異物付着を防止したり、転写効率が向上したり、さらなるクリーニング性が向上するなど、画質安定性に対し多くの効果を同時に得ることが可能となる。
【０２３９】
請求項１３によれば、電子写真感光体に、少なくとも帯電、露光、現像、転写及びクリーニングの工程が順次繰り返されることによって画像形成を行う画像形成装置において、該電子写真感光体が請求項１から１２のいずれか１項に記載の電子写真感光体であることを特徴とする画像形成装置によれば、これらの電子写真感光体を画像形成装置に用いることによって、画像流れの影響が抑制され、高画質化並びに画質安定化が実現される。これによって、画像形成装置の寿命を延ばすことが可能となる。
【０２４０】
請求項１４によれば、前記帯電手段に帯電ローラーを用いることを特徴とする請求項１３に記載の画像形成装置により、画像形成装置において、帯電手段として帯電ローラーを用いた場合、コロナ帯電の手段に比べてオゾン発生量が極めて少なく、オゾンやＮＯｘガスによる画像ボケの影響を軽減させることが可能とり、放電生成物の付着量は帯電ローラーの方が非常に多くなるが、本発明は、放電生成物が付着しても画像流れの発生を抑制させる方法であり、帯電ローラー及び本発明の感光体を用いることにより、オゾンやＮＯｘガスによる画像ボケと放電生成物付着による画像流れの両方の抑制が一度に実現が可能となる。
【０２４１】
請求項１５によれば、前記現像時に用いられるトナーが球形もしくは略球形であることを特徴とする請求項１３又は１４に記載の画像形成装置により、球形トナーを用いることによって、転写効率が向上し高画質化に対し非常に有効であるが、球形であることによりクリーニング性が大幅に低下するため使用する上で不具合が生じるのに対し、本発明では、保護層表面に交差する線状傷が形成されたことによって、球形トナーの転がりを抑えると同時に感光体の離型性を高めることが可能となりクリーニング性を向上させる効果が可能となる。感光体表面の線状傷が一方向の場合では転がりを抑制できず十分なクリーニング性は得られないが、少なくとも２方向から交差する線状傷を形成することにより、トナーの転がりを抑え、さらに離型性をより高めることが可能となり、それによってクリーニング性が顕著に高まり、球形トナーを使いこなすことが可能となり、それによって高画質化及び画質安定化に対し顕著な効果を得ることが可能となる。
【０２４２】
請求項１６によれば、該電子写真感光体にトナー像を現像した後、中間転写体もしくは中間転写ベルトを介して紙に転写する転写手段を有することを特徴とする請求項１３から１５のいずれか１項に記載の画像形成装置により、感光体から中間転写体もしくは中間転写ベルトへトナーを転写させる工程において、感光体からトナーが転写されずに残ってしまい、中抜け等の画像欠陥が発生しやすくなる不具合があるのに対し、本発明においては、感光体表面に交差する線状傷が形成されているために、感光体とトナーの過剰な付着力を低減することが可能となり、それによって中間転写体もしくは中間転写ベルトへの転写性を高めることが可能となる。それによって、中抜け等の画像欠陥を抑制することが可能となり、高画質化が実現される。また、転写効率が向上できたことにより、クリーニングに与える負荷を低減させ、クリーニング効率の向上にも寄与できる。
【０２４３】
請求項１７によれば、前記画像形成装置において、前記クリーニング手段に少なくともクリーニングブレードを用いていることを特徴とする請求項１３から１６のいずれか１項に記載の画像形成装置により、本発明におけるクリーニング工程は、トナー粒子だけをクリーニングするのではなく、感光体に付着した放電生成物をも除去する効果が要求されるが、この場合、クリーニングブラシよりも感光体の表面に常に接触しているクリーニングブレードが有効である。クリーニングブレードを用いることによって、感光体表面に付着した放電生成物のクリーニングにも効果が得られる上に、形成した線状傷に放電生成物を閉じ込める上でも好適かつ有効なクリーニング方法である。
【０２４４】
請求項１８によれば、前記電子写真感光体表面にシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物を付着させる手段を有することを特徴とする請求項１３から１７のいずれか１項に記載の画像形成装置により、保護層表面にシリコーン系化合物、フッ素系化合物、長鎖アルキル基含有化合物等の滑性成分を含む化合物を付着させることによって感光体表面に滑り性を付与し、それによって離型性を高めたり、異物付着を軽減したり、摩耗量を低減させたり、多くの効果を得ることができるが、本発明においては感光体表面に少なくとも２方向から交差する線状傷を形成したことによって、それらの滑性成分を含む化合物が線状傷に入り込み、感光体表面全体を汚染することなく、滑り性を付与する効果の持続性が高まる。さらに、それによって滑性成分を含む化合物の使用量は少なくすることも可能であり、これらの滑性成分を含む化合物の過剰な付着によって引き起こされていた異常画像の発生を抑制することも可能となる。
【０２４５】
請求項１９によれば、前記電子写真感光体の最表面に互いに交差する無数の線状傷を形成する手段を含んでいることを特徴とする請求項１３から１８のいずれか１項に記載の画像形成装置により、感光体は経時で摩耗するため、形成させた線状傷は摩耗によって消えることになり、それによって画像流れ抑制効果の持続性が低下することになるのに対し、画像形成装置の使用経時で感光体表面に線状傷を形成させることにより、画像流れ抑制効果を半永久的に持続させることが可能となり、感光体の画質安定化が実現される。また、使用経時で線状傷を形成させる工程が加わることにより、感光体表面にリフェイス効果、すなわち感光体表面に付着したフィルミング物を除去する効果が得られ、高画質化に対しさらなる効果が得られることが可能となる。
【０２４６】
請求項２０によれば、請求項１から１２のいずれか１項に記載の電子写真感光体を具備し、画像形成装置本体に対し着脱自在の構造を有することを特徴とする画像形成装置用プロセスカートリッジにより、感光体周りのメンテナンスが容易となる。特に、本発明においては感光体表面に線状傷を形成させる上で適している。
【図面の簡単な説明】
【図１】本発明における感光体の層構成の一例を示す概略図である。
【図２】本発明における感光体の層構成の他の一例を示す概略図である。
【図３】本発明における感光体の層構成のさらに他の一例を示す概略図である。
【図４】本発明の感光体表面の一例を示す概略図である。
【図５】本発明の感光体表面の他の一例を示す概略図である。
【図６】本発明の感光体表面の一例を示す概略図である。
【図７】本発明の感光体表面に形成した線状傷の断面の一例を示す概略図である。
【図８】本発明の感光体表面に形成した線状傷の断面の他の一例を示す概略図である。
【図９】本発明の画像形成プロセス及び画像形成装置を説明するための概略図である。
【図１０】本発明の帯電方法の一例を示す概略図である。
【図１１】本発明による画像形成プロセスの別の例を示した図である。
【図１２】本発明による画像形成プロセスの別の他の例を示した図である。
【図１３】本発明におけるプロセスカートリッジを示した一般的な図である。
【図１４】本発明の感光体製造例８におけるＸＤスペクトルを示した図である。
【図１５】感光体表面に線状傷を形成する方法を示した一例である。
【図１６】感光体表面に線状傷を形成する別な方法を示した一例である。
【符号の説明】
１ 感光体
２ 除電ランプ
３ 帯電チャージャ
４ イレーサ
５ 画像露光部
６ 現像ユニット
７ 転写前チャージャー
８ レジストローラ
９ 転写紙
１０ 転写チャージャー
１１ 分離チャージャー
１２ 分離爪
１３ クリーニング前チャージャー
１４ ファーブラシ
１５ ブレード
１６ 帯電ローラ
１７ ギャップ材
１８ 像形成領域
１９ クリーニング
２０ 中間転写ベルト
３１ 導電性支持体
３３ 感光層
３５ 電荷発生層
３７ 電荷輸送層
３９ 保護層
１０１ 感光ドラム
１０２ 帯電装置
１０３ 露光
１０４ 現像装置
１０５ 転写体
１０６ 転写装置
１０７ クリーニングブレード
１０８ クリーニングブラシベルト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge for the image forming apparatus. More specifically, the surface of the photosensitive member is improved to reduce the occurrence of image flow due to adhesion of foreign matter to the surface of the electrophotographic photosensitive member. The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge for an image forming apparatus that achieve high durability, high image quality, and stable image quality.
[0002]
[Prior art]
In recent years, laser printers and digital copying machines that record information using light by converting information into digital signals have significantly improved print quality and reliability. Furthermore, they have been applied to laser printers or digital copiers capable of full-color printing by fusing with high-speed technology.
[0003]
As electrophotographic photoreceptors used in these electrophotographic laser printers, digital copying machines, etc., those using organic photosensitive materials are generally widely applied for reasons such as cost, productivity and non-pollution. Has been. Organic photoreceptors include photoconductive resins typified by polyvinylcarbazole (PVK), charge transfer complex types typified by PVK-TNF (2,4,7-trinitrofluorenone), phthalocyanine- A pigment dispersion type typified by a binder is known, and at present, a function separation type photoreceptor using a combination of a charge generation material and a charge transport material is widely applied.
[0004]
The mechanism of electrostatic latent image formation in the function-separated type photoconductor is that when the photoconductor is charged and then irradiated with light, the light passes through the charge transport layer and is absorbed by the charge generation material in the charge generation layer to generate a charge. . Charges generated thereby are injected into the charge transport layer at the interface between the charge generation layer and the charge transport layer, and further moved toward the surface by an electric field to neutralize the surface charge of the photoconductor, thereby neutralizing the surface. It forms an electrostatic latent image.
[0005]
However, organic photoreceptors are subject to wear due to repeated use, and as the photosensitive layer wears, deterioration of image quality such as lowering of the charging potential, lowering of photosensitivity, lowering of density and background contamination is promoted. There is a strong tendency, and conventionally, wear resistance has been cited as a major issue in organic photoreceptors. Furthermore, in recent years, the wear resistance of the photosensitive member has become an even more important issue due to the reduction in the diameter of the photosensitive member accompanying the increase in the speed of the electrophotographic device or the miniaturization of the electrophotographic device.
[0006]
As the film thickness of the photosensitive layer on the photoconductor becomes thinner due to wear, the electric field strength increases, and image defects such as background stains tend to occur remarkably. On the other hand, when the film thickness of the photosensitive layer is increased more than necessary in consideration of wear, there is a tendency that the resolution is greatly lowered and the image quality is deteriorated. Also, if the amount of film thickness reduction is large during repeated use, the image quality tends to fluctuate and the photoconductor must be replaced in a short cycle. Therefore, it is very important to improve the wear resistance of the photosensitive member and reduce the film thickness variation in order to improve the image quality and stabilize it over time.
[0007]
As means for improving the abrasion resistance of the photoreceptor, methods of curing the outermost surface layer of the photoreceptor or containing a filler are known and effective and useful. Although it has been possible to improve the wear resistance by these methods, new problems have arisen with respect to higher image quality. This is to promote the generation of an abnormal image by adhering and depositing foreign matter on the surface of the photoreceptor, and is one of the biggest causes that hinders the improvement in image quality and durability of the electrophotographic apparatus.
[0008]
One of these abnormal images is image flow. This is thought to be caused by the resistance of the surface of the photoconductor decreasing due to the discharge products generated by charging adhering to the surface of the photoconductor, and the charge spreading in the lateral direction. The effect is noticeable below. Conventional photoconductors with poor abrasion resistance are easily removed by abrasion of the surface of the photoconductor even if these discharge products adhere to the photoconductor, so that image flow hardly occurs.
[0009]
However, with the improvement of the wear resistance of the photoconductor, it becomes difficult to remove the discharge products adhering to the surface of the photoconductor, and the occurrence of image flow is the biggest factor that hinders the high durability of the photoconductor. It was.
[0010]
As a conventional technique for suppressing the image flow due to the adhesion of these discharge products, a method for heating the photoreceptor is disclosed (for example, see Patent Documents 1 to 3).
Also disclosed is a method of incorporating an antioxidant into the photosensitive layer (see, for example, Patent Documents 4 to 7).
In particular, the method of dehumidifying the photosensitive member by heating is very effective for image flow. However, in order to heat the photosensitive member, it is necessary to enclose a heater in the electrophotographic apparatus, and thus the size of the apparatus cannot be avoided. In addition, since it is necessary to constantly heat the photoconductor, there is a problem that causes a significant increase in power consumption.
[0011]
Furthermore, in the case of a small-diameter photoconductor that has become the mainstream in recent years, it has been difficult to enclose a heater in spite of the fact that higher durability is required. On the other hand, the method of adding an antioxidant to the surface of the photoconductor is effective in suppressing the deterioration of the electrostatic characteristics of the photoconductor due to ozone or NOx gas generated by charging, but discharge that adheres to the surface of the photoconductor. Actually, no effect was obtained on the product.
[0012]
Other causes of abnormal images include adhesion of toner external additives and paper dust. This is because the foreign matter adhered to the surface of the photoconductor is accumulated every time it is used repeatedly, so that innumerable spots may appear in the image in the future, or they may cause image flow due to moisture intake. .
[0013]
In the prior art, attempts have been made to improve the releasability of the surface of the photoreceptor by reducing the friction coefficient and surface energy of the surface of the photoreceptor. For example, fluorine-modified silicone oil (for example, see Patent Documents 8 to 10), silicone resin fine particles (for example, see Patent Documents 11 and 12), fluorine-containing resin fine particles (for example, see Patent Document 13), and the like are disclosed.
[0014]
However, although these methods can greatly reduce the friction coefficient and the surface energy at the initial stage, they rapidly increased as printing was repeated, and the sustainability of the effect was extremely poor.
[0015]
Attempts have also been made to improve the releasability by roughening the surface of the photoreceptor. For example, a method is disclosed in which the surface of the photoreceptor has a shape in which peaks and valleys are regularly continuous in a direction having an angle with the axial direction of the photoreceptor (see, for example, Patent Document 14).
[0016]
However, although this method has an effect of improving the releasability, it does not mention image flow caused by discharge products. In the present invention, an effect cannot be obtained unless a shape in which peaks and valleys are regularly continuous intersects at least in two directions, and the configuration and effects differ from those of the present invention.
[0017]
Many other attempts have been made to roughen the photosensitive layer. For example, a photoconductor is disclosed in which a vacuum thin film is formed on a photoconductive photosensitive layer whose surface is roughened by innumerable linear scratches intersecting each other (see, for example, Patent Document 15).
[0018]
Although the surface roughening method is consistent with the present invention, the present invention forms intersecting linear scratches on the outermost surface of the photoreceptor, and the object, configuration and effect of the present invention are completely different.
[0019]
In improving the durability of the photoconductor, the improvement of wear resistance is realized, and at the same time, the occurrence of abnormal images such as image flow due to the appearance of discharge products and foreign matters has increased the wear resistance of the photoconductor. Doing so makes it easier for foreign matter to remain on the surface of the photoconductor, and trying to remove the foreign matter on the surface of the photoconductor sacrifices the wear resistance of the photoconductor, thus achieving both improved wear resistance and suppression of abnormal images. Was very difficult. Even if the photoconductor has high wear resistance, an abnormal image is generated at an early stage, which means that high durability of the electrophotographic apparatus has not been realized. While maintaining the wear resistance of the photoconductor, it is possible to suppress the image flow due to the adhesion of discharge products to the surface of the photoconductor, to realize the wear resistance and image quality of the photoconductor, and also to stabilize the image quality. It was the biggest problem in realizing high durability of photographic equipment.
[0020]
[Patent Document 1]
Japanese Patent Laid-Open No. 1-191883
[Patent Document 2]
JP-A-1-206386
[Patent Document 3]
JP-A-1-233474
[Patent Document 4]
JP 59-136744 A
[Patent Document 5]
Japanese Patent Laid-Open No. 2-64549
[Patent Document 6]
Japanese Patent Laid-Open No. 2-64550
[Patent Document 7]
JP-A-8-292585
[Patent Document 8]
JP 7-295248 A
[Patent Document 9]
JP-A-7-301936
[Patent Document 10]
JP-A-8-82940
[Patent Document 11]
Japanese Patent Laid-Open No. 07-128772
[Patent Document 12]
Japanese Patent Laid-Open No. 10-254160
[Patent Document 13]
JP-A 63-65449
[Patent Document 14]
JP 2001-66814 A
[Patent Document 15]
Japanese Patent No. 2987922
[0021]
[Problems to be solved by the invention]
In the above prior art, as described above, the occurrence of an abnormal image such as an image flow that has been manifested by improving the wear resistance of the photoreceptor is the biggest problem that hinders the high durability of the electrophotographic apparatus. There is a trade-off between the wear resistance of the photoconductor and the occurrence of abnormal images due to adhesion of foreign matter on the photoconductor surface, and the discharge products attached to the photoconductor surface without significantly affecting the wear resistance of the photoconductor There has been a strong demand for means that can suppress the image flow caused by the above.
[0022]
In order to realize high durability of the electrophotographic photosensitive member, as described above, at the same time as improving the wear resistance, the influence of the image flow due to the discharge product adhering to the surface of the photosensitive member is suppressed. It is necessary to improve the image quality stability in repeated use. Conventionally, as the wear resistance of the photoconductor is improved, discharge products are likely to remain on the surface of the photoconductor, and the removal of these discharge products sacrifices the wear resistance of the photoconductor. There is a problem that the improvement of the wear resistance and the stabilization of the image quality by removing the discharge products have not been realized.
[0023]
Therefore, the present invention has been made to solve the above-mentioned problems, and as a result of intensive studies by the present inventors, the image flow due to the discharge products adhering to the surface of the photoconductor is affected by the shape of the photoconductor surface. Thus, the present inventors have found that by satisfying the constituent requirements described later, it is possible to suppress image flow due to adhesion of discharge products while maintaining the wear resistance of the photoreceptor, and the present invention has been completed.
[0024]
Accordingly, the present invention provides an electrophotographic photosensitive material that achieves high durability, high image quality, and stable image quality by a method capable of suppressing the occurrence of image flow due to adhesion of discharge products while maintaining the wear resistance of the photoconductor. An object is to provide a body, an image forming apparatus, and a process cartridge for the image forming apparatus.
[0025]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, according to the first aspect of the present invention, an electrophotographic photosensitive member used in an image forming apparatus for forming an image by sequentially repeating at least charging, exposure, development, transfer and cleaning steps. In the electrophotographic photosensitive member, a protective layer containing a filler is laminated on the surface of the electrophotographic photosensitive member, and an infinite number of linear scratches are formed continuously on the surface of the protective layer. Features.
[0026]
According to a second aspect of the invention, the electrophotographic photosensitive member according to the first aspect is characterized in that the width of the linear scratch is smaller than the particle diameter of the toner particles.
[0027]
According to a third aspect of the invention, the electrophotographic photosensitive member according to the first or second aspect is characterized in that the crossing angle of the linear scratches is within a range of 45 to 135 degrees.
[0028]
According to a fourth aspect of the invention, the electrophotographic photosensitive member according to any one of the first to third aspects is characterized in that an interval between the linear scratches is 50 μm or less.
[0029]
According to a fifth aspect of the present invention, the electrophotographic photosensitive member according to the first aspect is characterized in that the filler is a metal oxide.
[0030]
The invention according to claim 6 is characterized in that the electrophotographic photosensitive member according to claim 1 or 5 is characterized in that the metal oxide of the filler is alumina.
[0031]
In the invention according to claim 7, the average primary particle size of the filler is 0.01 to 3.0 μm. The electrophotographic photosensitive member according to any one of claims 1, 5, and 6 is characterized in that: To do.
[0032]
The invention according to claim 8 is characterized in that the binder resin contained in the protective layer is one of polycarbonate resin, polyarylate resin, acrylic or methacrylic resin. Features.
[0033]
The main feature of the electrophotographic photosensitive member according to claim 1 is that the binder resin contained in the protective layer is a polymer charge transport material.
[0034]
According to a tenth aspect of the present invention, the binder resin is a thermosetting resin or a photocurable resin. The electrophotographic photosensitive member according to any one of the first, eighth, and ninth aspects is a main feature.
[0035]
In the invention of claim 11, the protective layer further contains at least one of a silicone compound, a fluorine compound, and a long chain alkyl group-containing compound. The described electrophotographic photosensitive member is the main feature.
[0036]
According to a twelfth aspect of the present invention, the silicone compound, the fluorine compound, and the long-chain alkyl group-containing compound have a fine particle shape and are dispersed in the protective layer. The main feature is a photographic photoreceptor.
[0037]
According to a thirteenth aspect of the present invention, in an image forming apparatus that forms an image by sequentially repeating at least charging, exposing, developing, transferring, and cleaning steps on the electrophotographic photosensitive member, the electrophotographic photosensitive member is described in the first aspect. The image forming apparatus which is the electrophotographic photosensitive member according to any one of items 1 to 12 is the main feature.
[0038]
The main feature of the image forming apparatus of the thirteenth aspect is that a charging roller is used as the charging means.
[0039]
According to a fifteenth aspect of the present invention, the image forming apparatus according to the thirteenth or fourteenth aspect is characterized in that the toner used during the development is spherical or substantially spherical.
[0040]
According to a sixteenth aspect of the present invention, in any one of the thirteenth to fifteenth aspects, the toner image is developed on the electrophotographic photosensitive member and then transferred to paper via an intermediate transfer member or an intermediate transfer belt. The image forming apparatus described is a main feature.
[0041]
According to a seventeenth aspect of the present invention, the image forming apparatus according to any one of the thirteenth to sixteenth aspects has at least a cleaning blade as the cleaning unit.
[0042]
The image forming apparatus according to any one of claims 13 to 17, further comprising means for attaching a silicone compound, a fluorine compound, or a long-chain alkyl group-containing compound to the surface of the electrophotographic photosensitive member. Features the device.
[0043]
According to a nineteenth aspect of the present invention, there is provided the image forming apparatus according to any one of the thirteenth to eighteenth aspects, further comprising means for forming innumerable linear scratches intersecting each other on the outermost surface of the electrophotographic photosensitive member. Main features.
[0044]
A twentieth aspect of the invention is an image forming apparatus comprising the electrophotographic photosensitive member according to any one of the first to twelfth aspects and having a structure that is detachable from the main body of the image forming apparatus. The process cartridge is the main feature.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below. The discharge product is considered to be generated by ionic species generated by charging and moisture in the atmosphere. When these discharge products adhere to the surface of the photoconductor, the resistance of the photoconductor surface decreases, and the image It is believed that a flow will occur. Accordingly, it is possible to suppress the image flow depending on how much discharge products attached to the surface of the photoreceptor can be removed by cleaning. However, it is very difficult to remove discharge products as the wear resistance of the photoreceptor surface increases. The present invention makes it difficult to generate an image flow even when a discharge product adheres to a photoreceptor.
[0046]
The image flow occurs at high temperature and high humidity due to the discharge product adhering to the surface of the photoconductor, because the resistance of the portion where the discharge product adheres rapidly decreases, and the charge transferred from the charge generation layer It is considered that the charge is diffused in the lateral direction when it reaches the surface and the electrostatic latent image is blurred. Therefore, in order to suppress the image flow, it is preferable to reduce the adhesion amount of the discharge product, but it is very difficult when the wear resistance of the photoreceptor is increased. In the present invention, even if the discharge product adheres to the surface of the photosensitive member, the adhesion region is finely divided, and the image flow is suppressed by keeping the charge diffusion within the region.
[0047]
Hereinafter, the present invention will be described in more detail.
(1) The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus for forming an image by sequentially repeating steps of charging, exposure, development, transfer and cleaning, and a filler on the surface of the electrophotographic photosensitive member. The protective layer containing the above is laminated, and innumerable linear scratches intersecting each other are continuously formed on the surface of the protective layer.
[0048]
By containing a filler in the protective layer, a dramatic improvement in wear resistance is realized, but it becomes difficult to remove the charged product, and the image flow is remarkably generated. In the present invention, by forming innumerable linear scratches intersecting the surface of the photoreceptor on the protective layer, it becomes possible to improve the cleaning property first by improving the releasability and reducing the contact area with the cleaning blade.
[0049]
Further, the discharge product adhering to the surface of the photosensitive member is confined in the linear scratch after cleaning, and therefore, the charge diffusion region is limited only to the linear scratch. Thereby, it is possible to reduce the influence of the image flow.
[0050]
However, when there is only one direction of the linear scratch, the writing line parallel to the direction of the linear scratch suppresses the image flow without making the characters thick because the charge diffusion is suppressed. However, for the writing line perpendicular to the direction of the line-shaped scratch, the diffusion of electric charge is promoted, the characters become fat, and a significant reduction in resolution is recognized.
[0051]
In this way, when the linear flaw is in one direction, the direction of the linear flaw is generated in the image flow, which is not sufficient to suppress the image flow. By crossing the linear scratches from at least two directions, it is possible to suppress the diffusion of charges with respect to the writing lines in all directions, and it is possible to suppress the image flow.
[0052]
In the present invention, scratches formed on the surface of the photoreceptor from a developer, a cleaning blade, etc. by repeated use are also linear and can be handled as the linear scratches of the present invention. In this case, inclusion of a filler in the protective layer is suitable for forming linear scratches and is effective in the present invention.
[0053]
(2) The electrophotographic photoreceptor according to the present invention is characterized in that the width of the linear scratch is smaller than the particle diameter of the toner particles. As the width of the formed linear scratch is larger, the charge diffusion region becomes wider and the influence of image flow tends to increase. In addition, if the width of the linear scratch is larger than the particle size of the toner, the toner particle may enter the linear scratch, causing an abnormal image, or reducing the effect of the present invention. By making the width of the linear scratch to be formed at least smaller than the toner particle diameter, it is possible to suppress the influence thereof and to obtain a sufficient image flow suppression effect.
[0054]
(3) The electrophotographic photoreceptor according to the present invention is characterized in that the crossing angle of the linear scratches is within a range of 45 to 135 degrees. As the crossing angle of the linear flaws intersecting at least from two directions becomes smaller, the dependency of the image flow on the linear flaw direction increases, and the effect of suppressing the image flow decreases. By forming the crossing angle of the linear scratches within a range of at least 45 to 135 degrees, it is possible to suppress image flow for lines and dots in all directions.
[0055]
(4) The electrophotographic photoreceptor according to the present invention is characterized in that an interval between the linear scratches is 50 μm or less. If the interval between the linear scratches formed on the surface of the photoconductor is too large, the interval is not uniform, or the area of the linear scratches on the surface of the photoconductor is reduced, the effect of confining the discharge products decreases, and the image The effect of flow increases. By setting the interval between the linear scratches to at least 50 μm or less on the surface of the photoconductor, there is no unevenness in the effect of suppressing image flow, and a sufficient effect can be obtained.
[0056]
(5) The electrophotographic photosensitive member according to the present invention is characterized in that the filler is a metal oxide. When the filler is a metal oxide, it is particularly effective for improving the wear resistance of the photoreceptor.
[0057]
In the present invention, scratches formed on the surface of the photoreceptor from a developer, a cleaning blade, etc. by repeated use can also be treated as the linear scratches of the present invention. In this case, the metal oxide has a high hardness and a polishing property. Therefore, it is effective not only for improving the abrasion resistance of the photoreceptor, but also for forming appropriate linear scratches on the protective layer. In particular, the shape of the linear scratch formed by containing these metal oxides in the protective layer is very suitable for enhancing the effect of suppressing image blur, for example, the width of the scratch is narrow.
[0058]
(6) The electrophotographic photoreceptor according to the present invention is characterized in that the metal oxide is alumina. By using alumina as the filler, not only can the wear resistance be further improved, but it also has the advantage that image flow hardly occurs even in a high temperature and high humidity or ozone atmosphere. In the present invention, by forming linear scratches intersecting the surface of the protective layer, it is possible to simultaneously suppress image flow due to the charged product in addition to them, and it is possible to suppress any image defects. .
[0059]
(7) The electrophotographic photosensitive member according to the present invention is characterized in that the filler has an average primary particle size of 0.01 to 3.0 μm. If the average primary particle size of the filler is very large, the image quality is deteriorated and the effect of the present invention may be reduced by half. In addition, the width of the linear scratch formed on the surface of the photoconductor becomes very large, thereby spreading the charge diffusion region and reducing the effect of suppressing image flow.
[0060]
By setting the average primary particle size of the filler in the range of 0.01 to 3.0 μm, it is possible to suppress the deterioration of image quality and to narrow the width of the linear scratch formed on the surface of the photoreceptor. It is possible to increase the flow suppression effect.
[0061]
(8) The electrophotographic photoreceptor according to the present invention is characterized in that the binder resin contained in the protective layer is a polycarbonate resin, a polyarylate resin, an acrylic resin, or a methacrylic resin. The binder resin contained in the outermost surface layer of the photoconductor not only changes the abrasion resistance of the photoconductor, but also changes the width of the linear scratches formed on the surface of the photoconductor, which greatly affects the effect of suppressing image blur. To do. By using at least a polycarbonate resin, a polyarylate resin, an acrylic resin, or a methacrylic resin as the binder resin, it is suitable for sufficiently exhibiting the effect of suppressing image blur.
[0062]
(9) The electrophotographic photoreceptor according to the present invention is characterized in that the binder resin contained in the protective layer is a polymer charge transport material. By including a charge transport material for charge transfer together with the binder resin, the potential of the exposed area is stabilized and the image quality is stabilized. However, the binder resin has both a charge transport function and a binder function. By using the polymer charge transport material, it is possible to further improve the abrasion resistance of the photoreceptor, and at the same time, it is possible to narrow the width of the linear scratch formed on the surface of the photoreceptor. As a result, it is possible to improve the image flow suppression effect.
[0063]
(10) The electrophotographic photoreceptor according to the present invention is characterized in that the binder resin is a thermosetting resin or a photocurable resin. By curing and using the binder resin, it becomes possible to further improve the abrasion resistance of the photoreceptor, and is suitable for further exerting the effects of the present invention.
[0064]
In addition, by using a curable resin as a binder resin, innumerable linear flaws that intersect after application of the protective layer are formed, and then cured to form linear flaws and stabilize the effect. It is a very effective means.
[0065]
(11) The electrophotographic photoreceptor according to the present invention is characterized in that the protective layer further contains at least one of a silicone compound, a fluorine compound, and a long-chain alkyl group-containing compound. When the protective layer contains at least one of a silicone-based compound, a fluorine-based compound, and a long-chain alkyl group-containing compound, the coefficient of friction on the surface of the photoreceptor is reduced, and the cleaning property of the discharge product is improved, so that it can be easily removed. The effect becomes. Combined with the effect of the roughened surface and improved releasability, it is possible to further enhance the image flow suppression effect.
[0066]
Further, even when these compounds are contained on the surface of the photoreceptor, conventionally, the durability of the effect of reducing the friction coefficient was very poor, but in the present invention, linear scratches intersecting the outermost surface of the photoreceptor are present. By being formed, it is possible to increase the durability of the friction coefficient reduction effect. Since discharge products also cause the coefficient of friction to rise, confining them in linear scratches greatly increases the durability of the friction coefficient reduction effect, realizing higher image quality and stabilization, A synergistic effect can be obtained.
[0067]
(12) The electrophotographic photosensitive member according to the present invention is characterized in that the silicone compound, the fluorine compound, and the long chain alkyl group-containing compound have a fine particle shape and are dispersed in a protective layer. And When these compounds are contained in conventional image forming apparatuses, not only the friction coefficient reducing effect of the conventional image forming apparatus itself, but also thin and long linear scratches are easily formed on the surface of the photoreceptor, which is effective in the present invention.
[0068]
In addition, when the image forming apparatus includes a means for forming linear scratches on the surface of the photoreceptor, in the step of forming linear scratches on the surface of the photoreceptor, the silicone compound, the fluorine-based compound, and the long-chain alkyl group-containing compound are used. By having the shape of fine particles and being dispersed in the outermost surface layer of the photoconductor, the supply of these compounds to the photoconductor surface can be improved, and the durability of the friction coefficient can be remarkably increased. As a result, the image flow suppression effect is further enhanced, and at the same time, many effects on image quality stability are obtained, such as prevention of filming and foreign matter adhesion, improvement of transfer efficiency, and further improvement of cleaning properties. It becomes possible.
[0069]
(13) An image forming apparatus according to the present invention is an image forming apparatus that forms an image by sequentially repeating charging, exposing, developing, transferring, and cleaning steps on the electrophotographic photosensitive member. It is an electrophotographic photosensitive member described in any one of (1) to (12). By using the electrophotographic photosensitive member described in (1) to (12) in the image forming apparatus, the influence of the image flow is suppressed, and high image quality and stable image quality are realized.
[0070]
(14) The image forming apparatus according to the present invention is characterized in that a charging roller is used as the charging means in the image forming apparatus. When a charging roller is used as the charging means, the amount of ozone generated is extremely small compared to the corona charging means, and it is possible to reduce the influence of image blur due to ozone and NOx gas. There are much more charged rollers. The present invention is a method for suppressing the occurrence of image flow even when a discharge product adheres. By using a charging roller and the photoreceptor of the present invention, image blur due to ozone or NOx gas and an image due to discharge product adhesion are provided. Both flow constraints can be achieved at once.
[0071]
(15) The image formation according to the present invention is characterized in that, in the electrophotographic apparatus, the toner used during the development is spherical or substantially spherical. Use of the spherical toner is very effective for improving the transfer efficiency and improving the image quality. However, since the toner is spherical, there is a problem in using it because the cleaning property is greatly lowered.
[0072]
However, in the present invention, the effect of improving the cleaning property by suppressing the rolling of the spherical toner is obtained by forming the linear scratches intersecting the surface of the photoreceptor. If the surface of the photoreceptor has a linear scratch in one direction, rolling cannot be suppressed and sufficient cleaning properties cannot be obtained. However, by forming a linear scratch that intersects at least two directions, toner movement is completely suppressed. Furthermore, it is possible to further improve the releasability, thereby significantly improving the cleaning property and making it possible to make full use of the spherical toner, thereby achieving a remarkable effect on improving the image quality and stabilizing the image quality. It becomes.
[0073]
(16) The image forming apparatus according to the present invention includes a transfer unit that develops a toner image on the electrophotographic photosensitive member and transfers the toner image to paper via an intermediate transfer member or an intermediate transfer belt. It is characterized by. In the process of transferring the toner from the photosensitive member to the intermediate transfer member or the intermediate transfer belt, the toner remains without being transferred from the photosensitive member, and image defects such as voids are likely to occur.
[0074]
In the present invention, since linear scratches intersecting the surface of the photosensitive member are formed, it is possible to reduce excessive adhesion between the photosensitive member and the toner, and thereby to the intermediate transfer member or the intermediate transfer belt. It becomes possible to improve transferability. As a result, image defects such as voids can be suppressed, and high image quality can be achieved. Further, since the transfer efficiency can be improved, the load applied to the cleaning can be reduced, and the cleaning efficiency can be improved.
[0075]
(17) The image forming apparatus according to the present invention is characterized in that, in the image forming apparatus, at least a cleaning blade is used as the cleaning unit. The cleaning process in the present invention is required not only to clean the toner particles but also to remove the discharge products adhering to the photoreceptor. In this case, a cleaning blade that is always in contact with the surface of the photoreceptor is more effective than the cleaning brush. By using the cleaning blade, the cleaning product is effective for cleaning the discharge product attached to the surface of the photosensitive member, and is a suitable and effective cleaning method for confining the discharge product in the formed linear scratch.
[0076]
(18) The image forming apparatus according to the present invention is characterized in that the image forming apparatus has means for attaching a silicone compound, a fluorine compound, or a long-chain alkyl group-containing compound to the surface of the electrophotographic photosensitive member. . By attaching a compound containing these slipping components to the surface of the photoreceptor, the surface of the photoreceptor is made slippery, thereby improving releasability, reducing adhesion of foreign matter, reducing the amount of wear, Although many effects can be obtained, in the present invention, by forming linear scratches intersecting at least from two directions on the surface of the photoreceptor, the compound containing these slipping components enters the linear scratches, and the photoreceptor The durability of the effect of imparting slipperiness is increased without contaminating the entire surface. Further, the amount of the compound containing the slipping component can be reduced, and the occurrence of abnormal images caused by excessive adhesion of these compounds can be suppressed.
[0077]
(19) The image forming apparatus according to the present invention is characterized in that the image forming apparatus includes means for forming innumerable linear scratches intersecting each other on the outermost surface of the electrophotographic photosensitive member. Since the photoconductor wears with time, the formed linear scratches disappear due to wear, thereby reducing the sustainability of the image blur suppression effect. Therefore, by forming linear scratches on the surface of the photoconductor over time of use of the image forming apparatus, the effect of suppressing image flow can be maintained semipermanently, and the image quality of the photoconductor can be stabilized. In addition, by adding a process of forming linear scratches over time of use, a reface effect on the surface of the photoconductor, that is, an effect of removing filming matter adhering to the surface of the photoconductor, can be obtained. can get.
[0078]
(20) The process cartridge for an image forming apparatus according to the present invention is a process cartridge for an image forming apparatus in which at least the electrophotographic photosensitive member has a structure that is detachable from the main body of the image forming apparatus. The electrophotographic photosensitive member described in any one of (1) to (12) is used as a body. By providing the photosensitive member in the process cartridge having a structure that is detachable from the image forming apparatus main body, maintenance around the photosensitive member is facilitated. In particular, the present invention is suitable for forming linear scratches on the surface of the photoreceptor.
[0079]
As described above, a photoconductor with improved wear resistance of the photoconductor generates intense image flow in a high-temperature and high-humidity environment due to discharge products adhering to the surface of the photoconductor, improving the photoconductor's wear resistance and improving image quality. Stabilization was not realized.
[0080]
On the other hand, according to the present invention, even if a discharge product adheres to the surface of the photoconductor, it is determined that the image flow does not appear. Therefore, both improvement in wear resistance of the photoconductor and stabilization of the image quality can be realized. . Furthermore, the present invention also provides an effect of simultaneously improving transfer efficiency and cleaning performance, and is very effective for improving image quality. According to the present invention, it is possible to suppress the occurrence of abnormal images such as image flow and filming while maintaining the abrasion resistance of the photosensitive member, and it is possible to simultaneously improve the transfer efficiency and the cleaning property. This makes it possible to achieve high durability, high image quality, and stable image quality.
[0081]
Next, the electrophotographic photosensitive member used in the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an electrophotographic photosensitive member of the present invention. A photosensitive layer 33 and a protective layer 39 mainly composed of a charge generating material and a charge transporting material are sequentially provided on a conductive support 31. Yes. The protective layer, which is the outermost surface layer, contains a filler, and innumerable linear scratches are formed on the surface.
[0082]
FIG. 2 is a cross-sectional view showing the electrophotographic photosensitive member of the present invention. On a conductive support 31, a charge transport layer 37 mainly composed of a charge transport material and a charge generation composed mainly of a charge generation material. A layer 35 and a protective layer 39 are sequentially provided. The protective layer, which is the outermost surface layer, contains a filler, and innumerable linear scratches are formed on the surface.
[0083]
FIG. 3 is a cross-sectional view showing the electrophotographic photosensitive member of the present invention. On the conductive support 31, a charge generation layer 35 mainly composed of a charge generation material and a charge transport mainly composed of a charge transport material. A layer 37 and a protective layer 39 are sequentially provided. The protective layer 39, which is the outermost surface layer, contains a filler, and innumerable linear scratches are formed on the surface.
[0084]
The conductive support 31 has a volume resistance of 10¹⁰Films having conductivity of Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxides such as tin oxide, indium oxide, etc. are deposited or sputtered. Shaped or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc., and after making them into tubes by extruding, drawing, etc., cutting, super finishing, polishing, etc. A surface-treated tube or the like can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Laid-Open No. 52-36016 can be used as the conductive support 31.
[0085]
In addition, a material obtained by dispersing conductive powder in an appropriate binder resin and coating it on the support can also be used as the conductive support 31 of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic, thermosetting resin or photo-curing resin such as melamine resin, urethane resin, phenol resin, alkyd resin and the like can be mentioned. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
[0086]
Furthermore, a conductive layer is provided on a suitable cylindrical substrate by a heat-shrinkable tube containing the conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon. Can be used favorably as the conductive support 31 of the present invention.
[0087]
Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a structure in which a plurality of layers are laminated. First, the case of a laminated structure composed of the charge generation layer 35 and the charge transport layer 37 will be described. Each of the charge generation layer and the charge transport layer may be a single layer or a plurality of layers. Further, a charge transport layer may be formed on the charge generation layer, or vice versa.
[0088]
First, the charge generation layer 35 will be described. The charge generation layer 35 is a layer mainly composed of a charge generation material, and a binder resin can be used in combination as necessary. As the charge generation material, inorganic materials and organic materials can be used. Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, cadmium sulfide, cadmium sulfide-selenium, amorphous silicon, and the like. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.
[0089]
On the other hand, a known material can be used as the organic material. For example, a disazo pigment, an asymmetrical disazo pigment, a trisazo pigment, an azo pigment having a carbazole skeleton (described in JP-A-53-95033), an azo pigment having a distyrylbenzene skeleton (JP-A-53-133445), An azo pigment having a triphenylamine skeleton (described in JP-A-53-132347), an azo pigment having a diphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728), a fluorenone skeleton An azo pigment having an oxadiazole skeleton (described in JP-A-54-12742), an azo pigment having a bis-stilbene skeleton (described in JP-A-54-22834) No. 17733), an azo face having a distyryl oxadiazole skeleton (Described in JP-A No. 54-2129), azo pigments such as azo pigments having a distyrylcarbazole skeleton (described in JP-A No. 54-14967), azulenium salt pigments, squaric acid methine pigments, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, bisbenzimidazole pigments, and Examples thereof include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine. The phthalocyanine is represented by the following (general formula N).
[0090]
[Chemical 1]

[0091]
In the formula, M (central metal) represents a metal or metal-free (hydrogen) element. M (center metal) mentioned here is H, Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga , Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, TI , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Pa, U, Np, Am, etc., or oxide, chloride It consists of two or more elements such as fluoride, fluoride, hydroxide and bromide. The central metal is not limited to these elements. The charge generation material having a phthalocyanine skeleton in the present invention may have at least a basic skeleton of the general formula (N), a substance having a multimeric structure such as a dimer or trimer, and a higher order high-order substance. It may have a molecular structure. Also, the basic skeleton may have various substituents.
[0092]
Of these various phthalocyanines, oxotitanium phthalocyanine having TiO as the central metal, metal-free phthalocyanine, chlorogallium phthalocyanine, and the like are particularly preferable in view of the photoreceptor characteristics. These phthalocyanines are known to have various crystal systems. For example, in the case of oxotitanium phthalocyanine, α, β, γ, m, Y type, etc., in the case of copper phthalocyanine, α, β, γ, etc. It has a polycrystal system. Even in the phthalocyanine having the same central metal, various properties change as the crystal system changes. It has been reported that the characteristics of photoreceptors using phthalocyanine pigments having these various crystal systems also change accordingly (Electrophotographic Society Vol. 29, No. 4 (1990)). For this reason, the selection of the crystal system of phthalocyanine is very important for the characteristics of the photoreceptor, and among these, Y-type oxotitanium phthalocyanine is particularly effective and useful for increasing the sensitivity. These charge generation materials can be used alone or as a mixture of two or more.
[0093]
Examples of the binder resin used for the charge generation layer 35 include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate resin, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, poly Examples include acrylamide. These binder resins can be used alone or as a mixture of two or more. In addition to the above-described binder resin, the charge generating layer may be formed of a polymer charge transport material described later (for example, JP-A 64-1728, JP-A 64-13061, JP-A 64-19049, JP-A-4-11627, JP-A-4-22014, JP-A-4-230767, JP-A-4-320420, JP-A-5-232727, JP-A-6- No. 234838, JP-A-6-234839, JP-A-6-295077, JP-A-7-56374, JP-A-7-325409, JP-A-9-80772, and JP-A-9-80783. JP-A-9-80784, JP-A-9-127713, JP-A-9-211877, JP-A-9-222740, JP-A-9-26519 JP, Hei 9-265201, JP-A No. 9-297419, JP-A No. 9-304956 JP) can be used. The amount of the binder resin used in the charge generation layer 35 is 0 to 500 parts by weight, preferably 0 to 200 parts by weight with respect to 100 parts by weight of the charge generation material. Moreover, various additives, such as leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, a sensitizer, and a dispersing agent, can be added as needed.
[0094]
As a method for forming the charge generation layer 35, a vacuum thin film manufacturing method and a casting method from a solution dispersion system can be largely mentioned. As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed. In addition, in order to provide a charge generation layer by the casting method described later, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone together with the above-mentioned inorganic or organic charge generation material together with a binder resin as necessary. Disperse with a ball mill, attritor, sand mill, bead mill, etc. using a solvent such as cyclopentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc. it can. The application can be performed using a conventionally known method such as a dip coating method, spray coating, bead coating, or ring coating method. The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.
[0095]
The charge transport layer 37 can be formed by dissolving or dispersing at least a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer 35 and the like.
[0096]
Examples of the charge transport material include a hole transport material and an electron transport material. Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.
[0097]
Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.
[0098]
Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate. , Polyvinylidene chloride, polyarylate resin, phenoxy resin, acrylic resin, methacrylic resin, polycarbonate resin, epoxy resin, melamine resin, urethane resin, silicone resin, fluorine resin, cellulose acetate resin, ethyl cellulose resin, etc. You may mix and use seed | species or more resin.
[0099]
For the charge transport layer 37, a polymer charge transport material having a function as a binder resin and a function as a charge transport material is also preferably used. A charge transport layer composed of these polymer charge transport materials is excellent in wear resistance and effective. In the present invention, these polymer charge transport materials can be mixed with the aforementioned binder resin or low molecular charge transport material. As the polymer charge transport material, all known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the following formulas (I) to (X) are preferably used.
[0100]
[Chemical formula 2]

[0101]
[Wherein R₁, R₂, R₃Each independently represents a substituted and / or unsubstituted alkyl group or a halogen atom, R₄Is a hydrogen atom or a substituted and / or unsubstituted alkyl group, R₅, R₆Is a substituted and / or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j are compositions (molar fractions), 0.1 ≦ k ≦ 1, 0 ≦ j represents a number of 0.9, and n represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.
[0102]
[Chemical Formula 3]

[0103]
Where R₁₀₁, R₁₀₂Each independently represents a substituted and / or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched and / or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -SO₂-, -CO-, -CO-O-Z-O-CO- (Z represents an aliphatic divalent group), or
[0104]
[Formula 4]

[0105]
(A is an integer from 1 to 20, b is an integer from 1 to 2000, R₁₀₃, R₁₀₄Represents a substituted or unsubstituted alkyl group or aryl group. Where R₁₀₁And R₁₀₂, R₁₀₃And R₁₀₄May be the same or different. ]
[0106]
[Chemical formula 5]

[0107]
(Wherein R₇, R₈Is a substituted and / or unsubstituted aryl group, Ar₁, Ar₂, Ar₃Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0108]
[Chemical 6]

[0109]
(Wherein R₉, R₁₀Is a substituted and / or unsubstituted aryl group, Ar₄, Ar₅, Ar₆Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0110]
[Chemical 7]

[0111]
(Wherein R₁₁, R₁₂Is a substituted and / or unsubstituted aryl group, Ar₇, Ar₈, Ar₉Represents the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j, and n are the same as in the general formula (I). )
[0112]
[Chemical 8]

[0113]
(Wherein R₁₃, R₁₄Is a substituted and / or unsubstituted aryl group, Ar₁₀, Ar₁₁, Ar₁₂Are the same or different arylene groups, X₁, X₂Represents a substituted and / or unsubstituted ethylene group, or a substituted and / or unsubstituted vinylene group. X, k, j, and n are the same as in the general formula (I). )
[0114]
[Chemical 9]

[0115]
(Wherein R₁₅, R₁₆, R₁₇, R₁₈Is a substituted and / or unsubstituted aryl group, Ar₁₃, Ar₁₄, Ar₁₅, Ar₁₆Are the same or different arylene groups, Y₁, Y₂, Y₃Represents a single bond, a substituted and / or unsubstituted alkylene group, a substituted and / or unsubstituted cycloalkylene group, a substituted and / or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, May be different. X, k, j, and n are the same as in the general formula (I). )
[0116]
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[0117]
(Wherein R₁₉, R₂₀Represents a hydrogen atom, a substituted and / or unsubstituted aryl group, and R₁₉And R₂₀May form a ring. Ar₁₇, Ar₁₈, Ar₁₉Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0118]
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[0119]
(Wherein R₂₁Is a substituted and / or unsubstituted aryl group, Ar₂₀, Ar₂₁, Ar₂₂, Ar₂₃Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0120]
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[0121]
(Wherein R₂₂, R₂₃, R₂₄, R₂₅Is a substituted and / or unsubstituted aryl group, Ar₂₄, Ar₂₅, Ar₂₆, Ar₂₇, Ar₂₈Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0122]
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[0123]
(Wherein R₂₆, R₂₇Is a substituted and / or unsubstituted aryl group, Ar₂₉, Ar₃₀, Ar₃₁Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (I). )
[0124]
Hereinafter, some specific examples of the polycarbonate containing the triarylamine structure in the main chain and / or the side chain are shown below, but the present invention is not limited to these specific examples.
[0125]
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[0126]
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[0127]
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[0128]
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[0129]
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[0130]
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[0131]
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[0132]
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[0133]
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[0134]
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[0135]
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[0136]
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[0137]
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[0138]
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[0139]
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[0140]
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[0141]
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[0142]
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[0143]
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[0144]
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[0145]
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[0146]
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[0147]
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[0148]
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[0149]
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[0150]
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[0151]
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[0152]
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[0153]
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[0154]
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[0155]
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[0156]
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[0157]
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[0158]
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[0159]
These polymer charge transport materials having a triarylamine structure in the main chain or side chain are polymerized in the form of a homopolymer, a random copolymer, an alternating copolymer, or a block copolymer. And since these polymer charge transport materials have a role as a binder resin, it is necessary to have a film-forming ability. Therefore, the molecular weight is suitably 10,000 to 500,000, preferably 50,000 to 400,000, as the polystyrene-equivalent molecular weight Mw in the measurement by GPC.
These polymer charge transport materials are disclosed in JP-A-8-269183, JP-A-9-71642, JP-A-9-104746, JP-A-9-272735, JP-A-11-29634, JP-A-11-29634. 9-235367, JP-A-9-87376, JP-A-9-110976, JP-A-9-268226, JP-A-9-221544, JP-A-9-227669, JP-A-9- No. 157378, JP-A-9-302084, JP-A-9-302085, and JP-A-2000-26590.
[0160]
The content of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it can be used alone or in combination with other binder resins.
As the solvent used for coating the charge transport layer 37, the same solvent as the charge generation layer 35 can be used. Examples include solvents such as tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc. And those that dissolve the binder resin well are suitable. These solvents may be used alone or in combination of two or more.
[0161]
A leveling agent, an antioxidant, a plasticizer, or the like can be added to the charge transport layer 37 as necessary. Leveling agents that can be used in combination include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 1 part by weight is appropriate.
Antioxidants that can be used in combination include phenolic compounds, hindered phenolic compounds, hindered amine compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, organic phosphorus compounds, benzophenones, salsylates, benzoates. All conventionally known antioxidants such as triazoles and quenchers (metal complex salts) can be used. Moreover, the effect may increase remarkably by mixing and adding 2 or more types of antioxidant, and it is effective. The amount used is suitably about 0 to 5% by weight with respect to 100 parts by weight of the binder resin. In addition, as plasticizers that can be used in combination, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 to 30 weights with respect to 100 parts by weight of the binder resin. Part is appropriate.
[0162]
The coating can be performed using a known method such as a dip coating method, spray coating, bead coating, or ring coating method in the same manner as the charge generation layer 35, and the dip coating method is most preferably used. The thickness of the charge transport layer 37 is about 5 to 50 μm, and preferably about 10 to 30 μm in terms of image characteristics such as resolution and background stains and electrical characteristics such as charging potential and sensitivity.
[0163]
Next, the case where the photosensitive layer has a single layer structure 33 will be described. The photosensitive layer 33 is formed by dissolving or dispersing the above-described charge generation material, charge transport material, binder resin, etc. in an appropriate solvent, and coating and drying this on a conductive support. As the charge generation material and the charge transport material, the materials described above for the charge generation layer 35 and the charge transport layer 37 can be used. As the binder resin, in addition to the resin mentioned in the charge transport layer 37, the resin mentioned in the charge generation layer 35 may be mixed and used. In addition, the above-described polymer charge transporting material can be favorably used as the binder resin. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably. 50 to 150 parts by weight. The photosensitive layer is obtained by dissolving or dispersing a charge generating material and a binder resin together with a charge transporting material in a solvent such as tetrahydrofuran, dioxane, dichloroethane, cyclohexanone, toluene, methyl ethyl ketone, acetone, and dip coating, spray coating, bead coating, It can be formed by coating with a ring coat or the like. Further, if necessary, various additives such as the plasticizer, leveling agent, antioxidant and lubricant can be added. The film thickness of the photosensitive layer 33 is suitably about 5 to 25 μm.
[0164]
In the present invention, a protective layer is formed as the outermost surface layer on the charge transport layer, charge generation layer or photosensitive layer.
The protective layer of the photoreceptor contains a filler, which is particularly effective for improving wear resistance. These fillers include various organic fillers and inorganic fillers. Among them, silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconia, indium oxide, antimony oxide, bismuth oxide, calcium oxide, and antimony are doped. Metal oxides such as tin oxide and indium oxide doped with tin are effectively used in terms of wear resistance and image quality. Among these metal oxides, a metal oxide that is less likely to cause image blur is preferably a metal oxide having high electrical insulation. Examples of these metal oxides include alumina, zirconia, and titanium oxide. Of these, alumina is used effectively. Especially, α-type alumina, which has a hexagonal close-packed structure with high light transmission, high thermal stability and excellent wear resistance, suppresses image blur and improves wear resistance. It can be used most effectively in terms of coating film quality, light transmittance, and the like. On the other hand, when a conductive metal oxide is included in the outermost surface of the photoreceptor, the lateral resistance of the surface is lowered, and the lateral movement of the charge is likely to occur. It is necessary to control the resistance. Examples of these metal oxides include conductive materials such as tin oxide, zinc oxide, acid value indium, acid value antimony, tin oxide doped with antimony, and indium oxide doped with tin.
[0165]
The metal oxide used in the present invention is effective because it can be subjected to surface treatment with at least one kind of surface treatment agent. Photoreceptors containing metal oxides in the protective layer tend to increase the effect of image blur due to ozone and NOx gas, but the surface treatment agent controls the specific resistance of metal oxides and the pH at the isoelectric point. In some cases, the effect of suppressing image blur may be significantly increased by the surface treatment agent. The metal oxide surface treatment not only has the effect of suppressing image blur but also has the effect of improving the dispersibility of the metal oxide, improving the light transmittance of the coating film, suppressing coating film defects, and wear resistance. It is also effective for improving the resistance and suppressing uneven wear.
As the surface treatment agent, all conventionally used surface treatment agents can be used, but a surface treatment agent capable of maintaining the specific resistance of the metal oxide and the pH at the isoelectric point is preferable. The pH at the isoelectric point of the metal oxide can be changed by surface treatment. That is, the metal oxide treated with the acidic treatment agent moves to the acidic side, and the metal oxide treated with the basic treatment agent moves to the basic side, so in the configuration of the present invention, the surface treatment agent In view of the dispersibility of the metal oxide and the suppression of image blur, it is preferable to use a treatment agent that is more basic. For example, titanate coupling agents, aluminum coupling agents, zircoaluminate coupling agents and the like can be used particularly effectively. Al₂O₃TiO₂, ZrO₂Silicone, aluminum stearate, or the like, or a mixture thereof is also preferably used from the viewpoint of dispersibility of metal oxide and image blur.
[0166]
The average primary particle size of the metal oxide is preferably 0.01 to 3.0 μm from the viewpoint of light transmittance and wear resistance, and more preferably 0.1 to 1.5 μm. If the average primary particle size of the filler is very large, the image quality is deteriorated and the effect of the present invention may be reduced by half. In addition, the width of the linear scratch formed on the surface of the photoconductor becomes very large, thereby spreading the charge diffusion region and reducing the effect of suppressing image flow. Further, the sedimentation property of the filler is increased, and the liquid life may be reduced. When the average primary particle size of the filler is smaller than this, the cohesiveness becomes high and the wear resistance may be lowered. By setting the average primary particle size of the filler in the range of 0.01 to 3.0 μm, it is possible to suppress the deterioration of image quality and to narrow the width of the linear scratch formed on the surface of the photoreceptor. It is possible to increase the flow suppression effect. In order to increase the dispersibility of the filler, various additives can be added and are useful. In particular, the carboxylic acid compound can not only increase the dispersibility and stability of the metal oxide, but also suppress an increase in residual potential due to the addition of the metal oxide. Among these, polycarboxylic acid-based wetting and dispersing agents are highly effective because of their high effects. Any carboxylic acid compound may be used as long as it is a compound containing a carboxyl group in its molecular structure, such as a generally known organic fatty acid, high acid value resin or copolymer. For example, saturated and unsaturated fatty acids such as lauric acid, stearic acid, arachidic acid, behenic acid, adipic acid, oleic acid, maleic acid, maleic anhydride, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, Any carboxylic acid such as an aromatic carboxylic acid can be used. In addition, saturated polyester, unsaturated polyester, terminal carboxylic acid unsaturated polyester, styrene-maleic acid copolymer, styrene-maleic anhydride, and the like having a saturated or unsaturated hydrocarbon as a basic skeleton, at least one carboxyl group All the polymers, oligomers and copolymers to which are bonded are included, and not only the effect of suppressing the increase in residual potential but also the effect of improving the dispersibility of the metal oxide are high, so that they can be used more effectively. In the binder resin for these carboxyl protective layers, a polymer charge transport material can also be used effectively. In addition to the polymer charge transport materials described in the charge transport layer, any polymer charge transport material can be used. It can be used effectively. By using the polymer charge transport material, it is possible to improve the abrasion resistance and scratch resistance of the photoreceptor while maintaining the residual potential and sensitivity in terms of electrostatic characteristics.
[0167]
The protective layer of the photoreceptor can further contain a charge transport material. By containing the charge transport material in the protective layer, it is possible to reduce the residual potential and suppress the sensitivity deterioration. As the charge transport material used for the protective layer, all the charge transport materials described in the above-mentioned charge transport layer can be used.
[0168]
Various antioxidants can be further added to the protective layer of the photoreceptor, which is useful. Antioxidants contained in the present invention include phenolic compounds, hindered phenolic compounds, hindered amine compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, organic phosphorus compounds, benzophenones, All additives such as salicylates, benzotriazoles, quenchers (metal complex salts) and the like such as conventionally known antioxidants, ultraviolet absorbers and light stabilizers are included. Among these antioxidants, the hindered phenol structure is particularly effective for suppressing deterioration of the photoreceptor from active gases such as ozone and NOx due to repeated use over a long period of time and enhancing the image quality stability. It is known that compounds having both structures of a hindered amine structure are useful. The hindered phenol structure refers to a structure in which bulky atomic groups exist at both ortho positions of the phenolic hydroxyl group. On the other hand, the hindered amine structure refers to a structure in which a bulky atomic group exists in the vicinity of the amino nitrogen atom, and an aromatic amine or an aliphatic amine-based substance also corresponds to this, but more preferably 2,2,6,6- It is a compound containing a tetramethylpiperidine structure. The details of the mechanism of action of the compounds having both of these structures are not clear, but the presence of bulky atomic groups enhances steric hindrance, thereby suppressing the thermal vibration of amino nitrogen atoms and phenolic hydroxyl groups, It is presumed that the influence of the active gas from the outside could be stopped by improving the stability of the radical state. Examples of the compound having both a hindered phenol structure and a hindered amine structure include various compounds. Among them, 1- [2- [3- (3,5-di-t-butyl) represented by the following structural formula is used. -4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpyridine It is effective and useful for resolution reduction caused by ozone or NOx gas.
[0169]
Embedded image

(H)
[0170]
It is also possible to add an additive that imparts slipperiness to the photoconductor in the protective layer of the photoconductor, thereby improving the releasability of the photoconductor, increasing the wear resistance, and suppressing adhesion of foreign matter. It is very effective in doing. As the compound imparting slipperiness contained in the protective layer, any material may be used as long as the slipperiness is imparted by addition, but in particular, a silicone compound, a fluorine compound, and a long chain alkyl group are contained. Compounds are used effectively. The silicone compound includes any compound that contains Si in the molecular structure, and examples thereof include silicone oil, various modified silicone oils, silicone resins, and resin fine particles. The fluorine-based compound includes any compound having F in the molecular structure, and examples thereof include fluorine-modified silicone oil, various fluorine resins such as PTFE / PFA / PVDF, and resin fine particles. The long chain alkyl group-containing compound includes any material that contains a long chain alkyl group. As the carbon number, C10, preferably C12 or more is particularly effective. In particular, metal soaps are also preferably used, and zinc stearate is effective and useful among them.
Examples of organic solvents used in the protective layer-forming coating solution include tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, and the like. These mixed solvents are also effectively used. On the other hand, as the filler dispersion means, all conventionally known dispersion means such as a ball mill, an attritor, a sand mill, a bead mill, and an ultrasonic wave can be used. Or the method of mechanically mixing using well-known apparatuses, such as a Banbury mixer, a roll mill, and a twin-screw extruder, and shape | molding in a pellet form can also be mentioned. Extruded pellets can be molded over a wide temperature range, and a normal injection molding machine is used for molding.
For the formation of the protective layer, conventional coating methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating and the like can be used. Of these, the film thickness can be easily controlled, the dispersibility of the filler can be maintained satisfactorily, and the coating quality is superior, and spray coating is more preferable.
The coated photoreceptor is manufactured through a drying process by heating. As a film thickness of a protective layer, 0.5 micrometer-10 micrometers are preferable, and 2 micrometers-6 micrometers are more preferable.
[0171]
In the present invention, a myriad of minute line-shaped scratches intersecting the surface of the protective layer containing the filler formed on the outermost surface of the photoreceptor are continuously formed. 4, 5, and 6 show examples of the surface of the photoreceptor of the present invention, and FIGS. 7 and 8 show examples of cross-sectional views of the formed linear scratches. In the present invention, any photoreceptor is included as long as innumerable linear scratches intersecting the protective layer containing the filler are formed. As described above, an infinite number of linear scratches in at least two directions intersect to suppress image flow in any direction. The linear scratch formed on the protective layer may have any shape, and the direction of the linear scratch formed is not particularly limited. Further, the linear scratch is not necessarily a straight line, and the linear scratch may have a curved line or a wavy line as long as it has a certain directionality. Although it is necessary to suppress the image flow that the linear scratch intersects at least from two directions, since the charge diffusion region is easily limited by intersecting more than the three directions or the four directions, the image flow It becomes effective for the suppression. In addition, the narrower the width of the line-shaped scratch formed, the smaller the charge diffusion width, which is advantageous for high image quality. When the width of the linear scratch is larger than the toner width, the toner particles may enter the linear scratch and contaminate the photosensitive member. Therefore, it is preferable that the toner particle size is at least smaller than the toner particle size.
[0172]
The means for forming linear scratches intersecting the surface of the photoreceptor is not particularly limited, and conventionally known methods can be applied. It is also possible to form linear scratches on the protective layer of the produced photoreceptor, or to form linear scratches when the protective layer is laminated, for example, directly on the protective layer surface of the produced photoreceptor. Any method such as a method of abutting and rubbing an abrasive, a method of pressing a mold having irregularities on the surface of the protective layer of the photoconductor, a method of forming a linear scratch at the stage of applying the protective layer of the photoconductor Can be applied. Examples of abrasives to be brought into contact with the surface of the protective layer of the photoreceptor include natural fibers, chemical fibers, glass fibers, felts, cloths, etc., papers such as sandpaper, plastics such as films, etc. Any shape and material can be used as long as they form a linear scratch on the surface of the layer.
[0173]
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer 33. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.
These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention includes Al.₂O₃Anodic oxidation, organic materials such as polyparaxylylene (parylene), and SiO₂, SnO₂TiO₂, ITO, CeO₂A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0174]
In the photoreceptor of the present invention, an intermediate layer can be provided between the undercoat layer and the photosensitive layer or between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a generally used coating method as described above is employed. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.
[0175]
In the present invention, in order to improve the environmental resistance, at least one layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, an intermediate layer, etc., in particular for the purpose of preventing a decrease in sensitivity and an increase in residual potential. In addition, an antioxidant, a plasticizer, a lubricant, an ultraviolet absorber, a low molecular charge transport material, and a leveling agent can be added to each layer. Representative materials of these compounds are described below.
[0176]
Examples of the antioxidant that can be added to each layer include, but are not limited to, the following.
(A) Phenolic compounds
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5 '-Di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-t-butylphenol) 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2- Methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- [Mechi -3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-t-butylphenyl) buty Rick acid] glycol ester, tocopherols and the like.
(B) Paraphenylenediamines
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Examples include di-isopropyl-p-phenylenediamine and N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine.
(C) Hydroquinones
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone.
(D) Organic sulfur compounds
Examples include dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, and ditetradecyl-3,3'-thiodipropionate.
(E) Organophosphorus compounds
Examples include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, and tri (2,4-dibutylphenoxy) phosphine.
[0177]
Examples of the plasticizer that can be added to each layer include, but are not limited to, the following.
(A) Phosphate ester plasticizer
Examples include triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, and the like.
(B) Phthalate ester plasticizer
Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, dinonyl phthalate, diisononyl phthalate, phthalic acid Examples include diisodecyl, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, and dioctyl fumarate.
(C) Aromatic carboxylic ester plasticizer
Examples include trioctyl trimellitic acid, tri-n-octyl trimellitic acid, and octyl oxybenzoate.
(D) Aliphatic dibasic acid ester plasticizer
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl-n-decyl adipate, diisodecyl adipate, dicapryl adipate, diazeline 2-ethylhexyl, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, Examples include dioctyl tetrahydrophthalate and di-n-octyl tetrahydrophthalate.
(E) Fatty acid ester derivatives
Examples thereof include butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, and tributyrin.
(F) Oxyester plasticizer
Examples include methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, and tributyl acetyl citrate.
(G) Epoxy plasticizer
Epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, and the like.
(H) Dihydric alcohol ester plasticizer
Examples include diethylene glycol dibenzoate and triethylene glycol di-2-ethyl butyrate.
(I) Chlorine-containing plasticizer
There are chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl and the like.
(J) Polyester plasticizer
Examples include polypropylene adipate, polypropylene sebacate, polyester, and acetylated polyester.
(K) Sulfonic acid derivative
Examples include p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide.
(L) Citric acid derivative
Examples include triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and acetyl citrate-n-octyldecyl.
(M) Other
Examples include terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, and methyl abietic acid.
[0178]
Examples of the lubricating substance that can be added to each layer include, but are not limited to, the following.
(A) Hydrocarbon compounds
Examples include liquid paraffin, paraffin wax, microwax, and low-polymerized polyethylene.
(B) Fatty acid compounds
Examples include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid.
(C) Fatty acid amide compounds
There are stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide and the like.
(D) Ester compound
Examples include fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, and fatty acid polyglycol esters.
(E) Alcohol compounds
There are cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
(F) Metal soap
There are lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
(G) Natural wax
There are carnauba wax, candelilla wax, beeswax, whale wax, ibotarou, and montan wax.
(H) Other
Examples include silicone compounds and fluorine compounds.
[0179]
Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
(A) Benzophenone series
There are 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, etc. .
(B) Salsylate type
Examples include phenyl salicylate, 2,4-di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate.
(C) Benzotriazole type
(2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3′-tertiarybutyl 5) '-Methylphenyl) 5-chlorobenzotriazole.
(D) Cyanoacrylate type
Examples include ethyl-2-cyano-3,3-diphenyl acrylate and methyl 2-carbomethoxy 3 (paramethoxy) acrylate.
(E) Quencher (metal complex)
Nickel (2,2 'thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate, and the like.
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- There are 2,2,6,6-tetramethylpiperidine and the like.
[0180]
Next, the entire image forming apparatus of the present invention will be described in detail with reference to the drawings. In addition, the figure and description shown below are examples for demonstrating this invention, and are not limited to this.
[0181]
FIG. 9 is a schematic view for explaining the image forming apparatus of the present invention. The photoreceptor 1 of the present invention is used as the photoreceptor 1. The photosensitive member 1 has a drum shape, but may be a sheet shape or an endless belt shape.
The charging member 3 can use any one of non-contact charging by a corotron, scorotron, a solid state charger (solid state charger) or the like, or contact charging by a charging roller or a charging brush. Further, when the charging roller 16 is used, a gap is provided in the photosensitive member or the charging roller 16 as shown in FIG. 10, and the photosensitive member and the charging roller are arranged close to each other so as not to contact each other in the image forming region 18. Is also possible and effective. In particular, when lubricating substances are attached to the surface of the photoreceptor, they may be attached to the charging roller to promote contamination of the charging roller. Contamination of the charging roller 16 may cause uneven charging or promote contamination of the photoreceptor. Therefore, since the charging roller 16 and the photosensitive member 1 are arranged close to each other, an effect of suppressing them may be obtained, which is effective. As a method of placing the charging member 16 close to the photosensitive member 1, it is necessary to provide a gap in the non-image forming area of the photosensitive member 1. For example, the gap member 17 is provided on the charging member or on the photosensitive member side. Alternatively, it can be formed by providing flange portions set at both ends of the photosensitive member. In the present invention, any method can be used as long as the photosensitive member and the charging member are disposed in close proximity. Thus, when using a gap material, the gap material 17 needs to be insulating, and a material with high abrasion resistance is used effectively. The gap material can be used in any form such as tape, seal or tube. The thickness of the gap is preferably 10 to 200 μm, more preferably 20 to 100 μm, and further preferably 40 to 80 μm. If the gap is smaller than this, there will be more contact between the charging member and the photoconductor, and the merit of placing them closer will not be obtained, and the effect of image quality degradation will increase. If the gap is larger than this, charging will be stable. May deteriorate and charging unevenness may occur. Further, the charging member can be charged with a charge by superimposing an AC component on a DC component. By superimposing an alternating current component, it is possible to reduce charging unevenness, thereby suppressing image density unevenness and contrast deterioration, which is useful.
In the corona charging method using corotron or scorotron, the amount of discharge products adhering to the surface of the photoreceptor tends to be relatively small, but the amount of ozone generated tends to be very large. On the other hand, when a charging roller is used, the amount of ozone generated can be reduced, but the amount of discharge product attached tends to increase. Although ozone and discharge products are factors that have a large effect on image flow, etc., since the present invention is a means for suppressing image flow due to adhesion of discharge products, the effect is obtained when a charging roller is used as the charging means. It will be demonstrated more.
[0182]
Next, the image exposure unit 5 is used to form an electrostatic latent image on the uniformly charged photoconductor. As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
[0183]
Next, the developing unit 6 is used to visualize the electrostatic latent image formed on the photoreceptor. Examples of the development method include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.
[0184]
The developing unit 6 in the full-color electrophotographic apparatus has units corresponding to at least four colors of yellow, magenta, cyan, and black, and a system in which the developing units of four colors are close to one photosensitive member, Four color toners are separated and filled in one development unit, and the unit itself rotates in four stages to sequentially develop the four colors. The revolver method and each of the four units filled with four color toners In contrast, the tandem method shown in FIG.
[0185]
Preparation of toner is generally performed by pulverization or polymerization, but in recent years, a polymerization method has been used. It is known that a toner having a spherical shape can be easily obtained by polymerization, but because the toner has a spherical or substantially spherical shape, the releasability is improved, so that the toner remaining on the photoreceptor during transfer is small, It is possible to improve transfer efficiency and suppress abnormal images such as voids. However, since spherical or substantially spherical toner significantly reduces the cleaning properties, conventionally, it has been necessary to avoid the spherical or substantially spherical shape, so that sufficient transfer efficiency has not been obtained. . In the present invention, by forming linear scratches intersecting the photoconductor, it is possible to give a further effect to the transfer efficiency by improving the releasability and to greatly improve the cleaning performance. When the linear scratches formed on the surface of the photoconductor are in one direction, especially when they are formed in the circumferential direction of the photoconductor, spherical or substantially spherical toner is easy to roll and greatly reduces the cleaning performance. However, in the present invention, the linear flaws are formed so as to intersect with each other, so that it is possible to suppress the movement of the toner, and the contact area between the cleaning blade and the photosensitive member is reduced. It was possible to improve the cleaning property by reducing excessive friction.
[0186]
Next, the toner image visualized on the photosensitive member is transferred onto paper or an intermediate transfer member. FIG. 11 is a schematic diagram for explaining an image forming apparatus having a configuration in which the intermediate transfer belt 20 is in contact with the photoreceptor 1 in the present invention and the photoreceptor and paper are not in direct contact. The intermediate transfer member may be in the form of a drum, a sheet, or an endless belt. The toner image formed on the intermediate transfer member or the intermediate transfer belt 20 is immediately transferred to the paper 9. As these transfer means, conventional methods such as an electrostatic transfer method using a transfer charger and a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used.
[0187]
When the toner is transferred from the photoconductor, if the releasability of the photoconductor is low, the toner remains on the photoconductor, which may cause voids or image quality deterioration due to a decrease in transfer efficiency. In the present invention, since the effect of improving the releasability on the surface of the photoreceptor is also obtained, it has become possible to simultaneously improve the transfer efficiency and the suppression of voids. In addition, since the intermediate transfer belt is in contact with the photosensitive member and the photosensitive member and the paper are not in direct contact with each other, an effect of suppressing the adhesion of paper dust on the surface of the photosensitive member can be obtained. The adhesion of discharge products and toner external additives to the surface of the photoconductor attracts paper dust, which may promote filming. However, the photoconductor and paper are in direct contact using an intermediate transfer belt. By not having it, it is possible to greatly suppress the influence.
[0188]
FIG. 12 is a schematic view of an image forming apparatus that is a tandem type and includes an intermediate transfer belt 20. In the tandem type image forming apparatus, the toner image formed on each photoconductor is primarily transferred to the intermediate transfer member or the intermediate transfer belt 20 and the like, and then secondarily transferred to the transfer member (paper) 9. The construction in which each photoconductor and the paper 9 are not in direct contact is very effective for high durability and high image quality as described above. In particular, in a tandem type image forming apparatus, it is necessary to minimize deterioration with time between photoreceptors as much as possible, and not only the amount of wear on the photoreceptor surface but also the influence of contamination on the photoreceptor surface. When a large difference occurs between the two, a mechanism for forming one image by the four photoconductors causes image deterioration such as color reproducibility and resolution reduction. In particular, when a void occurs, the color reproducibility also decreases, and in the case of a color image, the influence of the image quality deterioration becomes very large. In the case of the tandem method, the influence of paper dust tends to be large among discharge products, toner external additives, and paper dust that are contaminants on the surface of the photoreceptor. This is because each photoconductor needs to be in contact with the paper until at least four colors have been transferred, and the amount of toner used differs depending on the type of color to be printed. Regardless, the photoreceptor must be in constant contact with the paper. For example, when printing only black, a mechanism that prevents the three photoconductors other than black from coming into contact with the paper is considered. It is common for the influence of to increase. Therefore, in the tandem image forming apparatus, when the toner image on the photosensitive member is primarily transferred to the intermediate transfer member or the intermediate transfer belt, the photosensitive member and the paper are not in direct contact with each other. By using this photoconductor, it becomes particularly effective not only for enhancing the durability of the photoconductor but also for suppressing image blurring and filming, improving color reproducibility and resolution, and the like.
[0189]
Next, a fur brush, a cleaning blade, or a combination thereof is used to clean the toner remaining on the photoconductor after transfer. In the present invention, only the toner remaining on the photoconductor surface is cleaned. In particular, since it is necessary to remove the discharge product adhering to the photosensitive member, a cleaning blade is preferably used as the cleaning means. By forming linear scratches intersecting the surface of the photoconductor, the contact area between the photoconductor and the cleaning blade can be reduced, thereby suppressing excessive friction and improving the cleaning performance. In addition, since the discharge products entered the linear scratches and the locations where the discharge products remained could be distinguished, the influence of image flow could be suppressed, and at the same time, the cleaning performance of the discharge products adhering to the photoreceptor surface was improved. As a result, the image quality can be improved and the stability thereof can be improved.
[0190]
In order to impart slipperiness, it is possible to attach a compound containing a slippery component to the surface of the photoreceptor. This is very effective for improving the releasability of the photosensitive member, increasing the wear resistance, and suppressing the adhesion of foreign matter. In particular, it is also effective for cleaning discharge products, and a synergistic effect can be obtained by combining with the photoreceptor of the present invention. As the compound imparting slipperiness contained in the protective layer, any material may be used as long as the slipperiness is imparted by addition, but in particular, a silicone compound, a fluorine compound, and a long chain alkyl group are contained. Compounds are used effectively. The silicone compound includes any compound that contains Si in the molecular structure, and examples thereof include silicone resins and resin fine particles. Any fluorine-based compound may be used as long as it contains F in its molecular structure, and examples thereof include various fluororesin fine particles such as PTFE, PFA, and PVDF. The long-chain alkyl group-containing compound includes any material that contains a long-chain alkyl group, and zinc stearate is particularly effective. In addition, polyolefin resin, silicon grease, fluorine grease, paraffin wax, fatty acid esters, graphite, molybdenum disulfide, and the like can be given. By attaching these slipperiness-imparting compounds to the surface of the photoconductor, the sustainability of the effect of imparting releasability to the photoconductor has been remarkably improved, but it is difficult to control the amount of adhesion, and excessive adhesion Then, filming was promoted, and abnormal images and uneven wear were caused. In the present invention, the formation of linear scratches intersecting with the surface of the photoconductor causes the compound containing these slipping components to enter the scratch, thereby maintaining the slidability effect imparted to the surface of the photoconductor. As a result, a sufficient effect can be obtained even with a small amount of adhesion, whereby contamination of the surface of the photoreceptor can be suppressed, and occurrence of abnormal images and uneven wear can be suppressed.
[0191]
As a means for attaching the compound containing these slipping components to the surface of the photoreceptor, any method can be used. Specifically, a method in which a solid substance of these compounds is brought into direct contact with the surface of the photoreceptor or a photoreceptor. And a method in which a brush is brought into contact with the developer and adhered through the brush, or a method in which these compounds are mixed and adhered to the developer.
[0192]
The linear scratches formed on the surface of the photoconductor in the present invention are preferably formed when the photoconductor is not used. However, since the influence of wear occurs with use of the photoconductor, the linear scratches are formed even after use. Therefore, it is possible to achieve both the wear resistance and the stabilization of the image quality, and the life of the photoreceptor can be greatly improved. Therefore, it is preferable that the image forming apparatus includes means for forming a linear scratch on the surface of the photoreceptor.
[0193]
Any means can be used for the image forming apparatus including means for forming linear scratches intersecting the surface of the photoreceptor of the present invention, but the abrasive is pressed against the photoreceptor as the image forming apparatus is used. The rubbing means is particularly effective. A linear scratch can be formed in any direction by bringing a polishing object into contact with the photosensitive member and reciprocating in the axial direction of the photosensitive member, rotating the photosensitive member, or simultaneously moving them. it can. In addition, the scratches on the photoreceptor mainly formed by the developer and the cleaning blade over the course of use of the photoreceptor are also included in the linear scratches of the present invention. However, since most of the scratches formed on the photoconductor are scratches in one direction in the circumferential direction of the photoconductor, it is necessary for the above means to further form a linear scratch in a direction intersecting the scratches. Preferably, it is effective to cross the wound within a range of 45 to 135 degrees. As a result, it is possible to suppress the image flow for lines in any direction. In addition, linear scratches are formed by pressing and rubbing the above-mentioned abrasive against the photoconductor, but at the same time, the effect of removing the filming material adhering to the surface of the photoconductor is also exhibited, which further improves image quality stabilization. Obtainable. The abrasion resistance of the photosensitive member is lowered by pressing and rubbing the polished material, but since this operation does not need to be performed at all times, the influence on the abrasion resistance of the photosensitive member is not great.
[0194]
Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, a charge removal lamp and a charge removal charger are used, and the exposure light source and the charging means can be used, respectively.
In addition, conventionally known processes such as document reading, paper feeding, fixing, and paper ejection that are not close to the photosensitive member can be used.
[0195]
The above-described image forming process illustrated exemplifies an embodiment of the present invention, and other embodiments are of course possible. For example, the light irradiation process includes image exposure, pre-cleaning exposure, and static elimination exposure. In addition, a pre-transfer exposure, an image exposure pre-exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.
[0196]
These image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in those apparatuses in the form of a process cartridge and detachable. Good. FIG. 13 is a schematic view showing an example of a process cartridge for an electrophotographic apparatus. The process cartridge for an image forming apparatus according to the present invention includes a photoconductor and a cleaning unit, and at least one of a charging unit, a developing unit, a transfer unit, and a charge eliminating unit is integrated into and removed from the image forming apparatus main body. This is a possible part. According to the present invention, there is provided an image forming apparatus in which the photosensitive member is built in a process cartridge having a configuration that is detachable from the image forming apparatus main body, and the process cartridge is built in a tandem type image forming apparatus. The image forming apparatus having a configuration in which the photoconductor built in the sheet does not directly contact with the paper in the transfer process, the image forming apparatus combining them, and their process cartridges are all included.
[0197]
【Example】
Hereinafter, although an example is given and the present invention is explained, the present invention is not restricted by an example. All parts are parts by weight.
[0198]
Photoconductor production example 1
An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition on an aluminum cylinder are sequentially applied and dried by dip coating, and an undercoat layer of about 3.0 μm, about A 0.2 μm charge generation layer and an approximately 20 μm charge transport layer were formed. Further, an electrophotographic photosensitive member 1 was prepared by laminating a protective layer having a thickness of about 5 μm thereon using a protective layer coating solution having the following composition.
Undercoat layer coating solution
The component ratio of the undercoat layer coating solution is shown below.
Alkyd resin
(Beccosol 1307-60, Dainippon Ink and Chemicals): 6 parts
Melamine resin
(Super Becamine G-821-60 Dainippon Ink and Chemicals): 4 parts
Titanium oxide powder
(“Taipere CR-EL” manufactured by Ishihara Sangyo Co., Ltd.): 40 parts
Methyl ethyl ketone: 50 parts
Charge generation layer coating solution
The component ratio of the charge generation layer coating solution is shown below.
Asymmetric bisazo pigment of the following structural formula (1): 2.5 parts
Embedded image

Polyvinyl butyral ("XYHL" manufactured by UCC): 0.5 parts
Methyl ethyl ketone: 80 parts
Cyclohexanone: 200 parts
Charge transport layer coating solution
The component ratio of the charge transport layer coating solution is shown below.
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Chemicals): 10 parts
Charge transport material of the following structural formula (2): 10 parts
Embedded image

Silicone oil ("KF50" manufactured by Shin-Etsu Chemical): 0.002 parts
Tetrahydrofuran: 120 parts
Protective layer coating solution
The component ratio of the protective layer coating solution is shown below.
Alumina (average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical): 2.0 parts
Unsaturated polycarboxylic acid polymer solution (acid value 180 mgKOH / g, nonvolatile content 50% “BYK-P104” manufactured by BYK Chemie): 0.06 parts
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Kasei) 10 parts
Charge transport material of the above structural formula (2): 8 parts
Tetrahydrofuran: 470 parts
Cyclohexanone: 200 parts
[0199]
Photoconductor production example 2
An electrophotographic photosensitive member 2 was prepared in the same manner as in the photosensitive member manufacturing example 1 except that the protective layer coating solution in the photosensitive member manufacturing example 1 was changed to a protective layer coating solution having the following composition.
[Protective layer coating solution]
Alumina (average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical): 5.0 parts
Unsaturated polycarboxylic acid polymer solution (acid value 180 mgKOH / g, nonvolatile content 50% “BYK-P104” manufactured by BYK Chemie): 0.06 parts
Polyarylate (U-6000, manufactured by Unitika): 10 parts
Charge transport material of the above structural formula (2): 8 parts
Tetrahydrofuran: 520 parts
Cyclohexanone: 230 parts
[0200]
Photoconductor Production Example 3
In Photoconductor Production Example 1, an electrophotographic photoreceptor 3 was produced in the same manner as in Photoconductor Production Example 1 except that the protective layer coating solution was changed to the following composition.
Protective layer coating solution
Silicone resin fine particles
(Average primary particle size: 0.5 μm, manufactured by Toshiba Silicone): 40 parts
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Chemicals): 10 parts
Charge transport material of the above structural formula (2): 7 parts
Tetrahydrofuran: 470 parts
Cyclohexanone: 200 parts
[0201]
Photoconductor Production Example 4
In Photoconductor Production Example 1, an electrophotographic photoconductor 4 was produced in the same manner as in Photoconductor Production Example 1 except that the protective layer coating solution was changed to the following composition.
Protective layer coating solution
Silica (average primary particle size: 0.1 μm, manufactured by Shin-Etsu Chemical): 3.5 parts
Acrylic resin (hydroxyl value 25 (mgKOH / g), non-volatile content 50%, manufactured by Hitachi Chemical): 14 parts
Guanamin resin (non-volatile content 70%, manufactured by Mitsui Cytec): 4.5 parts
Aromatic sulfonic acid (non-volatile content 40%, manufactured by Mitsui Cytec): 0.02 part
Charge transport material of the above structural formula (2): 7 parts
Tetrahydrofuran: 450 parts
Cyclohexanone: 200 parts
[0202]
Photoconductor Production Example 5
An electrophotographic photosensitive member 5 was prepared in the same manner as in the photosensitive member manufacturing example 1 except that the protective layer coating solution in the photosensitive member manufacturing example 1 was changed to the following composition.
Protective layer coating solution
alumina
(Average primary particle size: 0.3 μm, AA-03 manufactured by Sumitomo Chemical Co., Ltd.): 3.0 parts
Unsaturated polycarboxylic acid polymer (acid value 180 mgKOH / g, nonvolatile content 50% “BYK-P104” manufactured by BYK Chemie): 0.09 parts
Polymer charge transport material of the following structural formula: 15 parts
[0203]
Embedded image

Tetrahydrofuran: 500 parts
Cyclohexanone: 200 parts
[0204]
Photoconductor Production Example 6
In Photoconductor Production Example 1, an electrophotographic photoreceptor 6 was produced in the same manner as in Photoconductor Production Example 1 except that the protective layer coating solution was changed to the following composition.
Protective layer coating solution
Alumina (average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical): 3.5 parts
Unsaturated polycarboxylic acid polymer (acid value 180 mgKOH / g, nonvolatile content 50% “BYK-P104” manufactured by BYK Chemie): 0.06 parts
Fluororesin fine particles (average primary particle size: 1 μm, manufactured by Shamrock): 2.0 parts
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Kasei) 10 parts
Charge transport material of the above structural formula (2): 7 parts
Tetrahydrofuran: 500 parts
Cyclohexanone: 220 parts
[0205]
Photoconductor Production Example 7
In Photoconductor Production Example 1, the electrophotographic photoconductor was prepared in the same manner as Photoconductor Production Example 1, except that the charge generation layer coating solution, charge transport layer coating solution and protective layer coating solution were changed to the following. 7 was produced.
Charge generation layer coating solution
Polyvinyl butyral
("ESREC BX-1" manufactured by Sekisui Chemical Co., Ltd.): 5 parts
Methyl ethyl ketone: 400 parts
Titanyl phthalocyanine having XD spectrum shown in FIG. 14: 8 parts
Charge transport layer coating solution
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Chemicals): 10 parts
Charge transport material of the above structural formula (2): 10 parts
Silicone oil ("KF50" manufactured by Shin-Etsu Chemical): 0.002 parts
Tetrahydrofuran: 120 parts
Protective layer coating solution
alumina
(Average primary particle size: 0.3 μm, AA-03 manufactured by Sumitomo Chemical Co., Ltd.): 4.0 parts
Unsaturated polycarboxylic acid polymer (acid value 180 mgKOH / g, nonvolatile content 50% “BYK-P104” manufactured by BYK Chemie): 0.08 parts
Bisphenol Z polycarbonate
(Panlite TS-2050, manufactured by Teijin Chemicals): 10 parts
Charge transport material of the above structural formula (2): 10 parts
Tetrahydrofuran: 540 parts
Cyclohexanone: 230 parts
[0206]
Photoconductor Production Example 8
In Photoconductor Production Example 1, an electrophotographic photoconductor 8 was produced in the same manner as in Photoconductor Production Example 1 except that the thickness of the charge transport layer was about 25 μm and a protective layer was not formed thereon.
[0207]
Example 1
Crossing linear scratches as shown in FIG. 7 were formed on the electrophotographic photosensitive member 1 using a plastic wrapping film sheet (particle size: 15 μm, 3M). It was confirmed by observation with a laser microscope of the photosensitive member that the average width of the linear scratches was 3.5 μm, the distance between the linear scratches was 20 μm at maximum, and the crossing angle of the linear scratches was 60 to 120 degrees.
[0208]
Example 2
Crossing linear scratches as shown in FIG. 8 were formed on the electrophotographic photoreceptor 2 using a plastic wrapping film sheet (particle size: 15 μm, 3M). It was confirmed by observation of the photoreceptor with a laser microscope that the average width of the linear scratches was 3.5 μm, the maximum distance between the linear scratches was 10 μm, and the crossing angle of the linear scratches was 30 to 60 degrees.
[0209]
Example 3
Crossing linear scratches as shown in FIG. 6 were formed on the electrophotographic photosensitive member 3 using sandpaper (# 1000). It was confirmed by observing the photosensitive member with a laser microscope that the width of the linear scratches was 3 μm on average, the maximum distance between the linear scratches was 15 μm, and the crossing angle of the linear scratches was 90 degrees.
[0210]
Example 4
In the electrophotographic photoreceptor 4, after forming the protective layer, it was immediately brought into contact with a mold having a fine uneven shape, and linear scratches having the shape shown in FIG. 7 were crossed on the surface of the photoreceptor. It was confirmed by observing the photosensitive member with a laser microscope that the width of the linear scratches was 5 μm on average, the maximum distance between the linear scratches was 30 μm, and the crossing angle of the linear scratches was 90 degrees.
[0211]
Example 5
The electrophotographic photoreceptor 6 was brought into contact with a rotating brush to form intersecting linear scratches as shown in FIG. It was confirmed by observation of the photoreceptor with a laser microscope that the width of the linear scratches was an average of 4 μm, the distance between the linear scratches was a maximum of 40 μm, and the crossing angle of the linear scratches was about 90 degrees.
[0212]
Example 6
The electrophotographic photosensitive member 7 was brought into contact with a polishing grindstone to form intersecting linear scratches as shown in FIG. It was confirmed by observation of the photoreceptor with a laser microscope that the width of the linear scratches was 5 μm on average, the interval between the linear scratches was 30 μm at maximum, and the crossing angle of the linear scratches was about 90 degrees.
[0213]
The electrophotographic photoreceptors of Examples 1 to 6 produced as described above were mounted on a process cartridge for an electrophotographic apparatus, and a semiconductor laser having an image exposure light source wavelength of 655 nm (however, only the electrophotographic photoreceptor 7 was 780 nm) The image was output using a modified digital copier manufactured by Ricoh Co., Ltd. equipped with a charging roller and a cleaning blade. The toner used was non-spherical and had a particle size of about 8 μm.
Next, the photosensitive member was transferred to a process cartridge from which the development and cleaning blades were removed, the transfer was removed, and a free run with only charging was performed in an environment of 30 ° C. and 90% RH for 30 minutes. Thereafter, the image was returned to a normal process cartridge and image output was performed. Further, the electrophotographic photosensitive members of Examples 1 to 6 were each subjected to 50,000 sheets of paper run in a normal temperature and normal humidity (25 ° C., 60% RH) environment, and the amount of wear was determined from the film thickness difference before and after the run. . Note that linear flaws were formed in the axial direction of the photoconductor every 10,000 sheets by using the method shown in FIG. 15 or FIG. After printing 50,000 sheets, the photoconductor was transferred to an environment of 30 ° C. and 90% RH to output an image. The image rank was distinguished by the following symbols.
A: Good image with no image flow
○: Image flow is recognized, but there is no problem in quality
△: Level that clearly shows the image flow, makes it difficult to read characters, and makes dots scattered
×: Level where the dots are completely scattered by the image flow and the characters cannot be read
[0214]
[Table 1]

[0215]
Comparative Example 1
No linear scratch was formed on the electrophotographic photoreceptor 1.
[0216]
Comparative Example 2
The electrophotographic photosensitive member 2 was formed using a plastic wrapping film sheet (particle size: 15 μm, 3M), linear scratches were formed only in the circumferential direction of the photosensitive member, and the scratches were not crossed. The average width of the linear scratches was 3.5 μm, and the maximum distance between the linear scratches was 20 μm, which was confirmed by observation of the photoreceptor with a laser microscope.
[0217]
Comparative Example 3
The electrophotographic photosensitive member 3 was formed using a plastic wrapping film (particle size: 15 μm, 3M), linear scratches were formed only in the circumferential direction of the photosensitive member, and the scratches were not crossed. The average width of the linear scratches was 3.5 μm, and the maximum distance between the linear scratches was 20 μm, which was confirmed by observation of the photoreceptor with a laser microscope.
[0218]
Comparative Example 4
The electrophotographic photosensitive member 4 was made of sandpaper (# 2000), linear scratches were formed only in the axial direction of the photosensitive member, and the scratches were not crossed. It was confirmed by observing the photoreceptor with a laser microscope that the width of the linear scratches was 2.5 μm on average and the maximum distance between the linear scratches was 10 μm.
[0219]
Comparative Example 5
The electrophotographic photosensitive member 5 was brought into contact with a rotating brush to form linear scratches only in the circumferential direction of the photosensitive member, and the scratches were not crossed. It was confirmed by observation with a laser microscope of the photosensitive member that the average width of the linear scratches was 4 μm and the maximum distance between the linear scratches was 40 μm.
[0220]
Comparative Example 6
No linear scratches were formed on the electrophotographic photoreceptor 7.
[0221]
The electrophotographic photoreceptors of Comparative Examples 1 to 6 produced as described above were mounted on a process cartridge for an electrophotographic apparatus, and a semiconductor laser having an image exposure light source wavelength of 655 nm (however, only the electrophotographic photoreceptor 8 was 780 nm) The image was output using a modified digital copier manufactured by Ricoh Co., Ltd. equipped with a charging roller and a cleaning blade. The toner used was non-spherical and had a particle size of about 8 μm.
Next, the photosensitive member was transferred to a process cartridge from which development and cleaning had been removed, transfer was removed, and a free run with only charging was performed in an environment of 30 ° C. and 90% RH for 30 minutes. Thereafter, the image was returned to a normal process cartridge and image output was performed. Further, the electrophotographic photoreceptors of Comparative Examples 1 to 6 were each subjected to 50,000 sheets of paper run in a normal temperature and normal humidity (25 ° C., 60% RH) environment, and the amount of wear was determined from the film thickness difference before and after the run. . Note that no linear flaws were formed over the passage of paper. After printing 50,000 sheets, the photoreceptor was moved to an environment of 30 ° C. and 90% RH, and image output was performed.
The image rank was distinguished by the following symbols.
A: Good image with no image flow
○: Image flow is recognized, but there is no problem in quality
△: Level that clearly shows the image flow, makes it difficult to read characters, and makes dots scattered
×: Level where the dots are completely scattered by the image flow and the characters cannot be read
[0222]
[Table 2]

[0223]
From the results in Tables 1 and 2, after forming a linear scratch that intersects the surface of the protective layer of the photoreceptor, a free run of only high-temperature and high-humidity charging is performed to force a certain amount of discharge product to adhere. However, it was confirmed that the image flow was suppressed. It can be seen that even if the image quality is partially reduced due to the charge-free free run, the recoverability is immediately recognized by the increase in the number of output sheets, and the discharge product is confined in the flaw and the influence of the image flow is reduced.
In addition, as the overall wear resistance increases, the effect of image flow tends to increase. However, even if the wear resistance is high, a polymer charge transport material is used or the outermost surface layer of the photoreceptor is lubricated. There is a tendency to increase the effect by adding a material having the property. On the other hand, if no linear scratches intersecting the surface of the photoconductor, or if the linear scratches are not intersected, no image blur suppression effect has been obtained, even if a lubricating substance is used. Even if it added, the effect was not enough. These tendencies are also reflected in the results of long-running paper runs, thereby achieving both wear resistance and image flow suppression.
[0224]
Next, the produced electrophotographic photosensitive members of Examples 1 to 6 and Comparative Examples 1 to 6 are mounted on a process cartridge for an electrophotographic apparatus, and a semiconductor laser having an image exposure light source wavelength of 655 nm is used, as shown in FIG. An image was output with a Ricoh Co., Ltd. full-color printer remodeling machine equipped with a charging system and a cleaning blade, and using substantially spherical toner, and image evaluation over time was performed. The particle size of the substantially spherical toner was about 6 μm.
The image rank was distinguished by the following symbols.
A: Good image with no image defects
○: Level with no problem in image quality
Δ: Image defect is confirmed, but is legible
X: Level of image defect and unreadable
[0225]
[Table 3]

[0226]
From the results shown in Table 3, when spherical or substantially spherical toner was used, it was recognized that a streak-like image defect tends to occur due to poor cleaning. Although it can be slightly suppressed by forming linear scratches in the axial direction of the photoreceptor or adding a lubricating substance to the surface of the photoreceptor, the effect is insufficient. However, by forming the intersecting linear scratches on the surface of the photoconductor of the present invention, it becomes possible to suppress streak-like image defects due to poor cleaning, and to use spherical or substantially spherical toner. It was.
[0227]
【The invention's effect】
As described above, according to claim 1, in the electrophotographic photosensitive member used for the image forming apparatus for forming an image by sequentially repeating at least the steps of charging, exposing, developing, transferring and cleaning, the electron By the electrophotographic photoreceptor, wherein a protective layer containing a filler is laminated on the surface of the photographic photoreceptor, and innumerable linear scratches intersecting each other are continuously formed on the surface of the protective layer, By including a filler in the protective layer of the electrophotographic photosensitive member and forming linear scratches intersecting the surface, the discharge product adheres to the surface of the photosensitive member while improving the abrasion resistance of the photosensitive member. However, the image flow can be suppressed. By causing the line-shaped scratches formed on the surface of the photosensitive member to intersect at least from two directions, it is possible to obtain an image flow suppressing effect even for writing lines having all angles. As a result, it is possible to improve both the wear resistance of the photoconductor and the suppression of image flow.
[0228]
According to a second aspect of the present invention, the width of the linear scratch is smaller than the particle size of the toner particles, and the charge diffusion region is made sufficiently small by the electrophotographic photosensitive member according to the first aspect. As a result, the effect of suppressing the image flow is enhanced. In addition, there is an effect of preventing image defects by preventing the toner from entering the scratches, which makes it possible to achieve high image quality.
[0229]
According to a third aspect of the present invention, the crossing angle of the linear flaws is in the range of 45 to 135 degrees. When the crossing angle is small, the effect of crossing the linear scratches is reduced, and the image flow suppression effect is reduced by the written line angle, and a sufficient suppression effect cannot be obtained. By forming so as to be within the range of 45 to 145 degrees, it is possible to suppress the image flow for lines and dots in all directions, and it is possible to sufficiently obtain the image flow suppression effect.
[0230]
According to a fourth aspect of the present invention, in the electrophotographic photosensitive member according to any one of the first to third aspects, the distance between the linear scratches is 50 μm or less. If the interval between the formed linear scratches is too large, the interval is not uniform, or the area of the linear scratches on the surface of the photoconductor is reduced, the confinement effect of the discharge product is reduced or unevenness occurs. While the influence of the image flow increases, by making the interval between the linear scratches at least 50 μm or less, there is no unevenness in the effect of suppressing the image flow, and a sufficient effect can be obtained.
[0231]
According to claim 5, the filler is a metal oxide. According to the electrophotographic photoreceptor of claim 1, the wear resistance of the photoreceptor due to the filler being a metal oxide. This is particularly effective for improving the performance. In the present invention, the scratches formed on the surface of the photoreceptor from the developer, the cleaning blade, etc. by repeated use are also linear, and can be handled as the linear scratches of the present invention. In this case, since many metal oxides have high hardness and polishing properties, they are effective not only for improving the abrasion resistance of the photoreceptor, but also for forming linear scratches on the outermost surface of the photoreceptor. . In particular, the shape of a linear scratch formed by containing these metal oxides on the surface of the photoreceptor can increase the effect of suppressing image blur, for example, the width of the scratch is narrow.
[0232]
According to claim 6, according to the electrophotographic photoreceptor according to claim 1 or 5, wherein the filler metal oxide is alumina, by using alumina as the metal oxide, ozone or It is possible to suppress image flow due to NOx and image blur in a high temperature and high humidity environment. By containing alumina in the protective layer and forming linear scratches that intersect the surface, it is possible to further suppress the image flow due to the adhesion of charged products, thereby improving the abrasion resistance of the photoreceptor. At the same time, many image defects can be suppressed.
[0233]
The electrophotographic photosensitive member according to any one of claims 1, 5, and 6, wherein the filler has an average primary particle size of 0.01 to 3.0 µm. Therefore, if the average primary particle size of the filler is very large, the image quality is deteriorated and the effect of the present invention may be halved. In addition, the width of the linear scratch formed on the surface of the photoconductor becomes very large, thereby spreading the charge diffusion region and reducing the effect of suppressing image flow. By setting the average primary particle size of the filler in the range of 0.01 to 3.0 μm, it is possible to suppress the deterioration of image quality and to narrow the width of the linear scratch formed on the surface of the photoreceptor. It is possible to increase the flow suppression effect.
[0234]
According to claim 8, the binder resin contained in the protective layer is any one of polycarbonate resin, polyarylate resin, acrylic or methacrylic resin. According to the body, the binder resin contained in the protective layer not only changes the abrasion resistance of the photoconductor, but also changes the width of the linear scratch formed on the surface of the photoconductor, which greatly reduces the effect of suppressing image blur. Affect. By using at least a polycarbonate resin, a polyarylate resin, an acrylic resin or a methacrylic resin for the binder resin, it is possible to sufficiently exhibit the image blur suppression effect.
[0235]
According to claim 9, the binder resin contained in the protective layer is a polymer charge transport material. According to the electrophotographic photosensitive member according to claim 1, charge transfer is performed together with the binder resin. For this reason, the potential of the exposed portion is stabilized by containing a charge transport material for the purpose, and the stabilization of the image quality is realized. However, as a binder resin, a polymer charge transport material having both a charge transport function and a binder function is used. By using it, it is possible to further improve the wear resistance of the photoconductor, and at the same time, it is possible to reduce the width of the linear scratch formed on the surface of the photoconductor. As a result, it is possible to improve the image flow suppression effect.
[0236]
The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a thermosetting resin or a photocurable resin. By curing and using the resin, it is possible to further improve the wear resistance of the photoreceptor, and it is suitable for further exhibiting the effects of the present invention. In addition, by using a curable resin as a binder resin, innumerable linear scratches that intersect after application of the outermost surface layer of the photoreceptor are formed, and then cured to form linear scratches and stabilize the effect. It becomes possible to become a very effective means in realizing.
[0237]
According to Claim 11, at least one of a silicone compound, a fluorine compound, and a long-chain alkyl group-containing compound is further contained in the protective layer. If the protective layer contains at least one of a silicone-based compound, a fluorine-based compound, and a long-chain alkyl group-containing compound in the protective layer, the coefficient of friction on the surface of the photoreceptor is reduced, and discharge is generated. The effect of facilitating removal can be obtained by improving the cleaning property of the object. Combined with the effect of the roughened surface and improved releasability, it is possible to further enhance the image flow suppression effect. Further, even when these compounds are contained on the surface of the photoreceptor, conventionally, the durability of the effect of reducing the friction coefficient was very poor, but in the present invention, linear scratches crossing the protective layer are formed. As a result, it is possible to increase the sustainability of the friction coefficient reduction effect. In addition, since the discharge products also cause the friction coefficient to increase, confining them in the linear flaw significantly increases the sustainability of the friction coefficient reduction effect, and provides many synergistic effects. It is possible to obtain a great effect on image quality and stabilization.
[0238]
According to Claim 12, the silicone compound, the fluorine compound, and the long-chain alkyl group-containing compound have a fine particle shape and are dispersed in the protective layer. According to the electrophotographic photosensitive member described in the above, the surface of a conventional electrophotographic photosensitive member contains a lubricating substance such as a silicone compound, a fluorine compound, or a long chain alkyl group-containing compound as fine particles, thereby forming an image. When the apparatus includes means for forming linear scratches on the surface of the photoreceptor, the silicone compound, the fluorine-based compound, and the long-chain alkyl group-containing compound have a fine particle shape in the step of forming the linear scratches on the photoreceptor surface. By having it and being dispersed in the outermost surface layer of the photoconductor, the supply of these compounds to the surface of the photoconductor is improved, and the durability of the friction coefficient can be remarkably increased. As a result, the image flow suppression effect is further enhanced, and at the same time, many effects on image quality stability are obtained, such as prevention of filming and foreign matter adhesion, improvement of transfer efficiency, and further improvement of cleaning properties. It becomes possible.
[0239]
According to a thirteenth aspect of the present invention, in an image forming apparatus that forms an image by sequentially repeating at least the steps of charging, exposing, developing, transferring, and cleaning on the electrophotographic photosensitive member, the electrophotographic photosensitive member from the first aspect. According to the image forming apparatus characterized in that the electrophotographic photosensitive member according to any one of 12 is used, the influence of image flow is suppressed by using these electrophotographic photosensitive members in the image forming apparatus, High image quality and stable image quality are realized. As a result, the life of the image forming apparatus can be extended.
[0240]
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, a charging roller is used as the charging means. The amount of ozone generation is extremely small compared to the above, and it is possible to reduce the effect of image blur due to ozone and NOx gas, and the amount of discharge product adhering to the charging roller is much larger. This is a method for suppressing the occurrence of image flow even if the product adheres. By using the charging roller and the photoreceptor of the present invention, both the image blur due to ozone and NOx gas and the image flow due to the discharge product adhesion are suppressed. Can be realized at once.
[0241]
According to a fifteenth aspect of the present invention, the toner used at the time of development is spherical or substantially spherical, and the transfer efficiency is improved by using the spherical toner in the image forming apparatus according to the thirteenth or fourteenth aspect. It is very effective for high image quality, but due to the spherical shape, the cleaning performance is greatly reduced, causing problems when used. On the other hand, in the present invention, linear scratches intersecting the protective layer surface are present. By being formed, it is possible to suppress the rolling of the spherical toner, and at the same time to improve the releasability of the photosensitive member, thereby improving the cleaning property. When the linear scratches on the surface of the photoreceptor are in one direction, rolling cannot be suppressed and sufficient cleaning properties cannot be obtained, but by forming linear scratches intersecting at least from two directions, toner rolling is suppressed, and It becomes possible to further improve the releasability, thereby significantly improving the cleaning property and making it possible to make full use of the spherical toner, thereby making it possible to obtain a remarkable effect on image quality improvement and image quality stabilization. .
[0242]
According to a sixteenth aspect of the present invention, the image forming apparatus further includes a transfer unit that develops the toner image on the electrophotographic photosensitive member and then transfers the toner image to paper through an intermediate transfer member or an intermediate transfer belt. In the process of transferring the toner from the photosensitive member to the intermediate transfer member or the intermediate transfer belt by the image forming apparatus described in item 1, the toner remains without being transferred from the photosensitive member, and image defects such as voids occur. However, in the present invention, since linear scratches intersecting the surface of the photoconductor are formed, it is possible to reduce excessive adhesion between the photoconductor and the toner. As a result, it is possible to improve transferability to the intermediate transfer member or the intermediate transfer belt. As a result, image defects such as voids can be suppressed, and high image quality can be achieved. Further, since the transfer efficiency can be improved, the load applied to the cleaning can be reduced, and the cleaning efficiency can be improved.
[0243]
The image forming apparatus according to any one of claims 13 to 16, wherein at least a cleaning blade is used as the cleaning unit in the image forming apparatus. The cleaning process is required not only to clean the toner particles but also to remove the discharge products adhering to the photoconductor. In this case, the surface is always in contact with the surface of the photoconductor rather than the cleaning brush. The cleaning blade is effective. By using the cleaning blade, the cleaning product is effective for cleaning the discharge product attached to the surface of the photosensitive member, and is a suitable and effective cleaning method for confining the discharge product in the formed linear scratch.
[0244]
According to claim 18, there is provided means for attaching a silicone compound, a fluorine compound, or a long-chain alkyl group-containing compound to the surface of the electrophotographic photosensitive member. With the image forming apparatus described, slipperiness is imparted to the surface of the photoreceptor by attaching a compound containing a slipping component such as a silicone compound, a fluorine compound, or a long-chain alkyl group-containing compound to the surface of the protective layer. Many effects can be obtained by improving releasability, reducing foreign matter adhesion, reducing the amount of wear, etc. In the present invention, linear scratches intersecting at least two directions are formed on the surface of the photoreceptor. As a result, the compound containing these slipping components penetrates into the linear scratches, and the durability of the effect of imparting slipperiness is increased without contaminating the entire surface of the photoreceptor. Furthermore, it is possible to reduce the amount of the compound containing the slipping component, and to suppress the occurrence of abnormal images caused by excessive adhesion of the compound containing the slipping component. Become.
[0245]
According to a nineteenth aspect, there is provided means for forming innumerable linear scratches intersecting each other on the outermost surface of the electrophotographic photosensitive member. The image forming apparatus wears the photoconductor over time, so that the formed linear scratches disappear due to wear, and the sustainability of the image flow suppression effect is thereby reduced. By forming linear scratches on the surface of the photoconductor over time, it is possible to maintain the effect of suppressing image flow semipermanently and to stabilize the image quality of the photoconductor. In addition, by adding a process of forming linear scratches over time of use, a reface effect on the surface of the photoconductor, that is, an effect of removing filming matter adhering to the surface of the photoconductor, can be obtained. Can be obtained.
[0246]
According to a twentieth aspect, the process for an image forming apparatus includes the electrophotographic photosensitive member according to any one of the first to twelfth aspects and has a structure that is detachable from the main body of the image forming apparatus. Maintenance around the photosensitive member is facilitated by the cartridge. In particular, the present invention is suitable for forming linear scratches on the surface of the photoreceptor.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a layer structure of a photoreceptor in the present invention.
FIG. 2 is a schematic view showing another example of the layer structure of the photoreceptor in the present invention.
FIG. 3 is a schematic view showing still another example of the layer structure of the photoreceptor in the present invention.
FIG. 4 is a schematic view showing an example of the surface of the photoreceptor of the present invention.
FIG. 5 is a schematic view showing another example of the surface of the photoreceptor of the present invention.
FIG. 6 is a schematic view showing an example of the surface of the photoreceptor of the present invention.
FIG. 7 is a schematic view showing an example of a cross section of a linear scratch formed on the surface of the photoreceptor of the present invention.
FIG. 8 is a schematic view showing another example of a cross-section of a linear scratch formed on the surface of the photoreceptor of the present invention.
FIG. 9 is a schematic view for explaining an image forming process and an image forming apparatus of the present invention.
FIG. 10 is a schematic view showing an example of a charging method of the present invention.
FIG. 11 is a diagram showing another example of an image forming process according to the present invention.
FIG. 12 is a diagram showing another example of the image forming process according to the present invention.
FIG. 13 is a general view showing a process cartridge according to the present invention.
FIG. 14 is a view showing an XD spectrum in photoreceptor production example 8 of the present invention.
FIG. 15 is an example showing a method of forming a linear scratch on the surface of a photoreceptor.
FIG. 16 is an example showing another method for forming linear scratches on the surface of a photoreceptor.
[Explanation of symbols]
1 Photoconductor
2 Static elimination lamp
3 Charger charger
4 Eraser
5 Image exposure section
6 Development unit
7 Pre-transfer charger
8 Registration roller
9 Transfer paper
10 Transcription charger
11 Separate charger
12 Separating nails
13 Charger before cleaning
14 Fur brush
15 blades
16 Charging roller
17 Gap material
18 Image formation area
19 Cleaning
20 Intermediate transfer belt
31 Conductive support
33 Photosensitive layer
35 Charge generation layer
37 Charge transport layer
39 Protective layer
101 Photosensitive drum
102 Charging device
103 exposure
104 Developing device
105 Transcript
106 Transfer device
107 Cleaning blade
108 Cleaning brush belt

Claims (16)

In an electrophotographic photosensitive member used in an image forming apparatus for forming an image by sequentially repeating at least charging, exposing, developing, transferring and cleaning steps, at least a filler and a binder resin are provided on the outermost surface of the electrophotographic photosensitive member. protective layer is provided which contains, and an electrophotographic photosensitive member, characterized in that the infinite number of linear flaws that cross each other only on the surface of the protective layer is continuously formed.   2. The electrophotographic photosensitive member according to claim 1, wherein the width of the linear scratch is smaller than the particle diameter of the toner particles.   The electrophotographic photosensitive member according to claim 1, wherein an intersection angle of the linear scratches is in a range of 45 to 135 degrees.   The electrophotographic photosensitive member according to claim 1, wherein an interval between the linear scratches is 50 μm or less.   The electrophotographic photosensitive member according to claim 1, wherein the filler is a metal oxide.   6. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide of the filler is alumina.   The electrophotographic photosensitive member according to claim 1, wherein an average primary particle size of the filler is 0.01 to 3.0 μm.   2. The electrophotographic photosensitive member according to claim 1, wherein the binder resin is one of a polycarbonate resin, a polyarylate resin, an acrylic resin, and a methacrylic resin.   The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a polymer charge transport material.   The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a thermosetting resin or a photocurable resin.   12. The image forming apparatus according to claim 1, wherein at least one of charging, exposure, development, transfer, and cleaning steps is sequentially repeated on the electrophotographic photosensitive member to form an image. An image forming apparatus comprising the electrophotographic photosensitive member described above.   The image forming apparatus according to claim 11, wherein a charging roller is used for the charging.   13. The image according to claim 11, further comprising a transfer unit that develops the toner image on the electrophotographic photosensitive member and then transfers the toner image to paper via an intermediate transfer member or an intermediate transfer belt. Forming equipment.   The image forming apparatus according to claim 11, wherein at least a cleaning blade is used for the cleaning.   The image forming apparatus according to claim 11, further comprising means for attaching a silicone compound, a fluorine compound, and a long-chain alkyl group-containing compound to the surface of the electrophotographic photosensitive member.   11. A process cartridge for an image forming apparatus comprising the electrophotographic photosensitive member according to claim 1 and having a structure that is detachable from a main body of the image forming apparatus.

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