JP2004233465A - Method of manufacturing dispersion, electrophotographic photoreceptor, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a dispersion containing titanyl phthalocyanine crystals having high crystal stability (little crystal transition) and a small grain size. <P>SOLUTION: The method of manufacturing the dispersion containing titanyl phthalocyanine crystals with a circulation type bead mill dispersion apparatus using dispersion media whose diameter is ≤1 mm, is characterised in that dispersion is carried out while measuring the rate of a circulating flow, and until the rate of the circulating flow reaches a prescribed rate from the start of dispersion, the output of a circulating member which supplies a liquid to a dispersion chamber, such as a pump is kept larger than output in a steady state. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立して置換もしく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もしくは無置換のアルキル基、Ｒ_５、Ｒ_６は置換もしく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は組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、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、または下記一般式で表される２価基を表す。
【０１０５】
【化２】

Ｒ_１０１、Ｒ_１０２は各々独立して置換もしくは無置換のアルキル基、アリール基また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、分岐状もしくは環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表す。）または、
【化３】

（ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換また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４】

式中、Ｒ_７、Ｒ_８は置換もしく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およびｎは、（１）式の場合と同じである。
【０１０７】
【化５】

式中、Ｒ_９、Ｒ_１０は置換もしく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およびｎは、（１）式の場合と同じである。
【０１０８】
【化６】

式中、Ｒ_１１、Ｒ_１２は置換もしく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、ｐは１〜５の整数を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。
【０１０９】
【化７】

式中、Ｒ_１３、Ｒ_１４は置換もしく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は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。
【０１１０】
【化８】

式中、Ｒ_１５、Ｒ_１６、Ｒ_１７、Ｒ_１８は置換もしく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、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしく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およびｎは、（１）式の場合と同じである。
【０１１１】
【化９】

式中、Ｒ_１９、Ｒ_２０は水素原子、置換もしく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およびｎは、（１）式の場合と同じである。
【０１１２】
【化１０】

式中、Ｒ_２１は置換もしく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およびｎは、（１）式の場合と同じである。
【０１１３】
【化１１】

式中、Ｒ_２２、Ｒ_２３、Ｒ_２４、Ｒ_２５は置換もしく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およびｎは、（１）式の場合と同じである。
【０１１４】
【化１２】

式中、Ｒ_２６、Ｒ_２７は置換もしくは無置換のアリール基、Ａｒ_２９、Ａｒ_{３ ０}、Ａｒ_３１は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。
【０１１５】
また、電荷輸送層に使用される高分子電荷輸送物質として、上述の高分子電荷輸送物質の他に、電荷輸送層の成膜時には電子供与性基を有するモノマーあるいはオリゴマーの状態で、成膜後に硬化反応あるいは架橋反応をさせることで、最終的に２次元あるいは３次元の架橋構造を有する重合体も含むものである。
【０１１６】
これら電子供与性基を有する重合体から構成される電荷輸送層、あるいは架橋構造を有する重合体は耐摩耗性に優れたものである。通常、電子写真プロセスにおいては、帯電電位（未露光部電位）は一定であるため、繰り返し使用により感光体の表面層が摩耗すると、その分だけ感光体にかかる電界強度が高くなってしまう。この電界強度の上昇に伴い、地汚れの発生頻度が高くなるため、感光体の耐摩耗性が高いことは、地汚れに対して有利である。これら電子供与性基を有する重合体から構成される電荷輸送層は、自身が高分子化合物であるため成膜性に優れ、低分子分散型高分子からなる電荷輸送層に比べ、電荷輸送部位を高密度に構成することが可能で電荷輸送能に優れたものである。このため、高分子電荷輸送物質を用いた電荷輸送層を有する感光体には高速応答性が期待できる。
【０１１７】
その他の電子供与性基を有する重合体としては、公知単量体の共重合体や、ブロック重合体、グラフト重合体、スターポリマーや、また、例えば特開平３−１０９４０６号公報、特開２０００−２０６７２３号公報、特開２００１−３４００１号公報等に開示されているような電子供与性基を有する架橋重合体などを用いることも可能である。この場合にも、先の移動度を満足できるような材料が有効に使用出来る。
【０１１８】
本発明においては、電荷輸送層３７中に可塑剤やレベリング剤を添加してもよい。
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など一般の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、結着樹脂に対して０〜３０重量％程度が適当である。
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など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に対して、０〜１重量％が適当である。
【０１１９】
結着樹脂としては、先に電荷輸送層３７で挙げた結着樹脂をそのまま用いるほかに、分散液の作製方法のところで挙げた結着樹脂を混合して用いてもよい。もちろん、先に挙げた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、結着樹脂１００重量部に対する電荷輸送物質の量は１〜１９０重量部が好ましく、さらに好ましくは５０〜１５０重量部である。
【０１２０】
単層感光層は、電荷発生物質、結着樹脂を必要ならば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、シクロヘキサン等の溶媒を用いて分散機等で分散した塗工液を、浸漬塗工法やスプレーコート、ビードコートなどで塗工して形成できる。単層感光層の膜厚は、５〜１００μｍ程度が適当である。
【０１２１】
本発明の電子写真感光体には、導電性支持体３１と感光層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。
【０１２２】
これらの下引き層は前述の感光層の如く適当な溶媒、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。
【０１２３】
本発明の電子写真感光体には、感光層保護の目的で、保護層が感光層の上に設けられることもある。近年、日常的にコンピュータの使用が行なわれるようになり、プリンタによる高速出力とともに、装置の小型化も望まれている。したがって、保護層を設け、耐久性を向上させることによって、本発明の高感度で異常欠陥のない感光体を有用に用いることができる。
【０１２４】
保護層に使用される材料としてはＡＢＳ樹脂、ＡＣＳ樹脂、オレフィン−ビニルモノマー共重合体、塩素化ポリエーテル、アリル樹脂、フェノール樹脂、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアクリレート、ポリアリルスルホン、ポリブチレン、ポリブチレンテレフタレート、ポリカーボネート、ポリアリレート、ポリエーテルスルホン、ポリエチレン、ポリエチレンテレフタレート、ポリイミド、アクリル樹脂、ポリメチルベンテン、ポリプロピレン、ポリフェニレンオキシド、ポリスルホン、ポリスチレン、ＡＳ樹脂、ブタジエン−スチレン共重合体、ポリウレタン、ポリ塩化ビニル、ポリ塩化ビニリデン、エポキシ樹脂等の樹脂が挙げられる。中でも、ポリカーボネートもしくはポリアリレートが最も良好に使用できる。
【０１２５】
保護層にはその他、耐摩耗性を向上する目的でポリテトラフルオロエチレンのような弗素樹脂、シリコーン樹脂、及びこれらの樹脂に酸化チタン、酸化錫、チタン酸カリウム、シリカ等の無機フィラー、また有機フィラーを分散したもの等を添加することができる。
【０１２６】
また、感光体の保護層に用いられるフィラー材料のうち有機性フィラー材料としては、ポリテトラフルオロエチレンのようなフッ素樹脂粉末、シリコーン樹脂粉末、ａ−カーボン粉末等が挙げられ、無機性フィラー材料としては、銅、スズ、アルミニウム、インジウムなどの金属粉末、シリカ、酸化錫、酸化亜鉛、酸化チタン、酸化インジウム、酸化アンチモン、酸化ビスマス、アンチモンをドープした酸化錫、錫をドープした酸化インジウム等の金属酸化物、チタン酸カリウムなどの無機材料が挙げられる。特に、フィラーの硬度の点からは、この中でも無機材料を用いることが有利である。特に、シリカ、酸化チタン、アルミナが有効に使用できる。
保護層中のフィラー濃度は使用するフィラー種により、また感光体を使用する電子写真プロセス条件によっても異なるが、保護層の最表層側において全固形分に対するフィラーの比で５重量％以上、好ましくは１０重量％以上、５０重量％以下、より好ましくは３０重量％以下程度が良好である。
【０１２７】
また、使用するフィラーの体積平均粒径は、０．１μｍ〜２μｍの範囲が良好に使用され、好ましくは０．３μｍ〜１μｍの範囲である。この場合、平均粒径が小さすぎると耐摩耗性が充分に発揮されず、大きすぎると塗膜の表面性が悪くなったり、塗膜そのものが形成できなかったりするからである。
なお、本発明におけるフィラーの平均粒径とは、特別な記載のない限り体積平均粒径であり、超遠心式自動粒度分布測定装置：ＣＡＰＡ−７００（堀場製作所製）により求めたものである。この際、累積分布の５０％に相当する粒子径（Ｍｅｄｉａｎ系）として算出されたものである。また、同時に測定される各々の粒子の標準偏差が１μｍ以下であることが重要である。これ以上の標準偏差の値である場合には、粒度分布が広すぎて、本発明の効果が顕著に得られなくなってしまう場合がある。
【０１２８】
また、本発明で使用するフィラーのｐＨも解像度やフィラーの分散性に大きく影響する。
その理由の一つとしては、フィラー、特に金属酸化物は製造時に塩酸等が残存することが考えられる。その残存量が多い場合には、画像ボケの発生は避けられず、またそれは残存量によってはフィラーの分散性にも影響を及ぼす場合がある。
【０１２９】
もう一つの理由としては、フィラー、特に金属酸化物の表面における帯電性の違いによるものである。通常、液体中に分散している粒子はプラスあるいはマイナスに帯電しており、それを電気的に中性に保とうとして反対の電荷を持つイオンが集まり、そこで電気二重層が形成されることによって粒子の分散状態を安定化している。粒子から遠ざかるに従いその電位（ゼータ電位）は徐々に低くなり、粒子から充分に離れて電気的に中性である領域の電位はゼロとなる。したがって、ゼータ電位の絶対値の増加によって、粒子の反発力が高くなることによって安定性は高くなり、ゼロに近づくに従い凝集しやすく不安定になる。一方、系のｐＨ値によってゼータ電位は大きく変動し、あるｐＨ値において電位はゼロとなり等電点を持つことになる。したがって、系の等電点からできるだけ遠ざけて、ゼータ電位の絶対値を高めることによって分散系の安定化が図られることになる。
【０１３０】
本発明の構成においては、フィラーとしては前述の等電点におけるｐＨが、少なくとも５以上を示すものが画像ボケ抑制の点から好ましく、より塩基性を示すフィラーであるほどその効果が高くなる傾向があることが確認された。等電点におけるｐＨが高い塩基性を示すフィラーは、系が酸性であった方がゼータ電位はより高くなることにより、分散性及びその安定性は向上することになる。
ここで、本発明におけるフィラーのｐＨは、ゼータ電位から等電点におけるｐＨ値を記載した。この際、ゼータ電位の測定は、大塚電子（株）製レーザーゼータ電位計にて測定した。
【０１３１】
更に、画像ボケが発生しにくいフィラーとしては、電気絶縁性が高いフィラー（比抵抗が１０^１０Ω・ｃｍ以上）が好ましく、フィラーのｐＨが５以上を示すものやフィラーの誘電率が５以上を示すものが特に有効に使用できる。また、ｐＨが５以上のフィラーあるいは誘電率が５以上のフィラーを単独で使用することはもちろん、ｐＨが５以下のフィラーとｐＨが５以上のフィラーとを２種類以上を混合したり、誘電率が５以下のフィラーと誘電率が５以上のフィラーとを２種類以上混合したりして用いることも可能である。また、これらのフィラーの中でも高い絶縁性を有し、熱安定性が高い上に、耐摩耗性が高い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の点から特に有用である。
【０１３２】
本発明において使用するフィラーの比抵抗は以下のように定義される。フィラーのような粉体は、充填率によりその比抵抗値が異なるので、一定の条件下で測定する必要がある。本発明においては、特開平５−９４０４９号公報の図１、特開平５−１１３６８８号公報の図１に示された測定装置と同様の構成の装置を用いて、フィラーの比抵抗値を測定し、この値を用いた。測定装置において、電極面積は４．０ｃｍ^２である。測定前に片側の電極に４ｋｇの荷重を１分間かけ、電極間距離が４ｍｍになるように試料量を調節する。測定の際は、上部電極の重量（１ｋｇ）の荷重状態で測定を行ない、印加電圧は１００Ｖにて測定する。１０^６Ω・ｃｍ以上の領域は、ＨＩＧＨ ＲＥＳＩＳＴＡＮＣＥ ＭＥＴＥＲ（横河ヒューレットパッカード）、それ以下の領域についてはデジタルマルチメーター（フルーク）により測定した。これにより得られた比抵抗値を本発明の云うところの比抵抗値と定義するものである。
【０１３３】
フィラーの誘電率は以下のように測定した。上述のような比抵抗の測定と同様なセルを用い、荷重をかけた後に、静電容量を測定し、これより誘電率を求めた。静電容量の測定は、誘電体損測定器（安藤電気製）を使用した。
【０１３４】
更に、これらのフィラーは少なくとも一種の表面処理剤で表面処理させることが可能であり、そうすることがフィラーの分散性の面から好ましい。フィラーの分散性の低下は残留電位の上昇だけでなく、塗膜の透明性の低下や塗膜欠陥の発生、さらには耐摩耗性の低下をも引き起こすため、高耐久化あるいは高画質化を妨げる大きな問題に発展する可能性がある。
【０１３５】
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、フィラーの絶縁性を維持できる表面処理剤が好ましい。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、高級脂肪酸等、あるいはこれらとシランカップリング剤との混合処理や、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がフィラーの分散性及び画像ボケの点からより好ましい。
シランカップリング剤による処理は、画像ボケの影響が強くなるが、上記の表面処理剤とシランカップリング剤との混合処理を施すことによりその影響を抑制できる場合がある。
【０１３６】
表面処理量については、用いるフィラーの平均一次粒径によって異なるが、３〜３０ｗｔ％が適しており、５〜２０ｗｔ％がより好ましい。表面処理量がこれよりも少ないとフィラーの分散効果が得られず、また多すぎると残留電位の著しい上昇を引き起こす。
【０１３７】
これらフィラー材料は単独もしくは２種類以上混合して用いられる。フィラーの表面処理量に関しては、上述のようにフィラー量に対する使用する表面処理剤の重量比で定義される。
これらフィラー材料は、適当な分散機を用いることにより分散できる。また、保護層の透過率の点から使用するフィラーは１次粒子レベルまで分散され、凝集体が少ない方が好ましい。
【０１３８】
また、保護層には残留電位低減、応答性改良のため、電荷輸送物質を含有しても良い。電荷輸送物質は、電荷輸送層の説明のところに記載した材料を用いることができる。電荷輸送物質として、低分子電荷輸送物質を用いる場合には、保護層中における濃度傾斜を設けても構わない。耐摩耗性向上のため、表面側を低濃度にすることは有効な手段である。
【０１３９】
ここでいう濃度とは、保護層を構成する全材料の総重量に対する低分子電荷輸送物質の重量の比を表わし、濃度傾斜とは上記重量比において表面側において濃度が低くなるような傾斜を設けることを示す。
また、高分子電荷輸送物質を用いることは、感光体の耐久性を高める点で非常に有利である。
【０１４０】
保護層の形成法としては通常の塗布法が採用される。なお保護層の厚さは０．１〜１０μｍ程度が適当である。また、以上のほかに真空薄膜作成法にて形成したａ−Ｃ、ａ−ＳｉＣなど公知の材料を保護層として用いることができる。
【０１４１】
上述したように、感光層（電荷輸送層）に高分子電荷輸送物質を使用したり、あるいは感光体の表面に保護層を設けることは、各々の感光体の耐久性（耐摩耗性）を高めるだけでなく、後述のようなタンデム型フルカラー画像形成装置中で使用される場合には、モノクロ画像形成装置にはない新たな効果をも生み出すものである。
【０１４２】
フルカラーの画像の場合、様々な形態の画像が入力されるが、逆に定型的な画像も入力される場合がある。例えば、日本語の文書等における検印の存在などである。検印のようなものは通常、画像領域の端の方に位置され、また使用される色も限定される。ランダムな画像が常に書き込まれているような状態においては、画像形成要素中の感光体には、平均的に画像書き込み、現像、転写が行なわれることになるが、上述のように特定の部分に数多くの画像形成が繰り返されたり、特定の画像形成要素ばかり使用された場合には、その耐久性のバランスを欠くことにつながる。
このような状態で表面の耐久性（物理的・化学的・機械的）の小さな感光体が使用された場合には、この差が顕著になり、画像上の問題になりやすい。一方、感光体を高耐久化した場合には、このような局所的な変化量が小さく、結果的に画像上の欠陥として現われにくくなるため、高耐久化を実現すると共に、出力画像の安定性をも増すことになり、非常に有効である。
【０１４３】
本発明の電子写真感光体においては、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、前述のごとく通常の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。
【０１４４】
次に図面を用いて本発明の画像形成プロセスならびに画像形成装置を詳しく説明する。
図５は、本発明の画像形成プロセス乃至画像形成装置を説明するための概略図であり、下記するような変形例も本発明の範疇に属するものである。
図５において、感光体１は導電性支持体上に特定の分散条件により分散されたチタニルフタロシアニン結晶を含有する電荷発生層と電荷輸送層が設けられてなる。帯電部材３、転写前チャージャー７、転写チャージャー１０、分離チャージャー１１、クリーニング前チャージャー１３には、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）、帯電ローラーを始めとする公知の手段が用いられる。
【０１４５】
帯電部材は、感光体１に対し接触もしくは近接配置したものが良好に用いられる。また、帯電部材により感光体に帯電を施す際、帯電部材に直流成分に交流成分を重畳した電界により感光体に帯電を与えることにより、帯電ムラを低減することが可能で効果的である。
ここでいう接触方式の帯電部材とは、感光体表面に帯電部材の表面が接触するタイプのものであり、帯電ローラー、帯電ブレード、帯電ブラシの形状がある。中でも帯電ローラーや帯電ブラシが良好に使用される。
【０１４６】
また、近接配置した帯電部材とは、感光体表面と帯電部材表面の間に１０〜２００μｍ以下の空隙（ギャップ）を有するように非接触状態で近接配置したタイプのものである。空隙の距離から、コロトロン、スコロトロンに代表される公知の帯電器とは区別されるものである。
本発明において使用される近接配置された帯電部材は、感光体表面との空隙を適切に制御できる機構のものであればいかなる形状のものでも良い。例えば、感光体の回転軸と帯電部材の回転軸を機械的に固定して、適正ギャップを有するような配置にすればよい。中でも、帯電ローラーの形状の帯電部材を用い、帯電部材の非画像形成部両端にギャップ形成部材を配置して、この部分のみを感光体表面に当接させ、画像形成領域を非接触配置させる、あるいは感光体非画像形成部両端ギャップ形成部材を配置して、この部分のみを帯電部材表面に当接させ、画像形成領域を非接触配置させる様な方法が、簡便な方法でギャップを安定して維持できる方法である。特に特開２００２−１４８９０４号公報、特開２００２−１４８９０５号公報に記載された方法は良好に使用できる。帯電部材側にギャップ形成部材を配置した近接帯電機構の一例を図６に示す。
【０１４７】
転写手段には、一般に上記の帯電器が使用できるが、図５に示されるように転写チャージャー１０と分離チャージャー１１を併用したものが効果的である。
【０１４８】
また、画像露光部５の光源にはＬＤもしくはＬＥＤが用いられる。除電ランプ２等の光源には、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。
【０１４９】
かかる光源等は、図５に示される工程の他に光照射を併用した転写工程、除電工程、クリーニング工程、あるいは前露光などの工程を設けることにより、感光体に光が照射される。
【０１５０】
さて、現像ユニット６により感光体１上に現像されたトナーは、転写紙９に転写されるが、全部が転写されるわけではなく、感光体１上に残存するトナーも生ずる。このようなトナーは、ファーブラシ１４およびブレード１５により、感光体より除去される。
クリーニングは、クリーニングブラシだけで行なわれることもあり、クリーニングブラシにはファーブラシ、マグファーブラシを始めとする公知のものが用いられる。
【０１５１】
電子写真感光体に正（負）帯電を施し、画像露光を行なうと、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。
かかる現像手段には、公知の方法が適用されるし、また、除電手段にも公知の方法が用いられる。
【０１５２】
図７には、本発明による画像形成プロセスの別の例を示す。感光体２１は導電性支持体上に、特定の分散条件により分散されたチタニルフタロシアニン結晶を含有する電荷発生層と電荷輸送層が設けられてなる。駆動ローラー２２ａ、２２ｂにより駆動され、帯電器２３による帯電、光源２４による像露光、現像（図示せず）、帯電器２５を用いる転写、光源２６によるクリーニング前露光、ブラシ２７によるクリーニング、光源２８による除電が繰返し行なわれる。図７においては、感光体２１（勿論支持体が透光性である）に支持体側より画像露光の光照射が行なわれる。また、画像露光源２４は、ＬＤもしくはＬＥＤが好ましく用いられる。
【０１５３】
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、図５において感光層側よりクリーニング前露光を行っているが、これは透光性支持体側から行ってもよいし、また、除電光の照射を支持体側から行ってもよい。
一方、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、およ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なうこともできる。
【０１５４】
以上に示すような画像形成手段は、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でそれら装置内に組み込まれてもよい。プロセスカートリッジとは、感光体を内蔵し、他に帯電手段、露光手段、現像手段、転写手段、クリーニング手段、除電手段の少なくとも１つを含んだ１つの装置（部品）である。プロセスカートリッジの形状等は多く挙げられるが、一般的な例として、図８に示すものが挙げられる。感光体１は導電性支持体上に特定の分散条件により分散されたチタニルフタロシアニン結晶を含有する電荷発生層と電荷輸送層が設けられてなる。
【０１５５】
図９は、本発明のタンデム方式のフルカラー画像形成装置を説明するための概略図であり、下記するような変形例も本発明の範疇に属するものである。
図９において、符号１Ｃ、１Ｍ、１Ｙ、１Ｋはドラム状の感光体であり、この感光体１Ｃ、１Ｍ、１Ｙ、１Ｋは図中の矢印方向に回転し、その周りに少なくとも回転順に帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋ、現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋ、クリーニング部材５Ｃ、５Ｍ、５Ｙ、５Ｋが配置されている。
【０１５６】
帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋは、感光体表面を均一に帯電するための帯電装置を構成する帯電部材である。この帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋと現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋの間の感光体裏面側より、図示しない露光部材からのレーザー光３Ｃ、３Ｍ、３Ｙ、３Ｋが照射され、感光体１Ｃ、１Ｍ、１Ｙ、１Ｋに静電潜像が形成されるようになっている。そして、このような感光体１Ｃ、１Ｍ、１Ｙ、１Ｋを中心とした４つの画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋが、転写材搬送手段である転写搬送ベルト１０に沿って並置されている。
【０１５７】
転写搬送ベルト１０は各画像形成ユニット６Ｃ、６Ｍ、６Ｙ、６Ｋの現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋとクリーニング部材５Ｃ、５Ｍ、５Ｙ、５Ｋの間で感光体１Ｃ、１Ｍ、１Ｙ、１Ｋに当接しており、転写搬送ベルト１０の感光体側の裏側に当たる面（裏面）には転写バイアスを印加するための転写ブラシ１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋが配置されている。
【０１５８】
各画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋは現像装置内部のトナーの色が異なることであり、その他は全て同様の構成となっている。
【０１５９】
図９に示す構成のカラー画像形成装置において、画像形成動作は次のようにして行われる。
まず、各画像形成要素６Ｃ、６Ｍ、６Ｙ、６Ｋにおいて、感光体１Ｃ、１Ｍ、１Ｙ、１Ｋが矢印方向（感光体と連れ周り方向）に回転する帯電部材２Ｃ、２Ｍ、２Ｙ、２Ｋにより帯電され、次に感光体の内側に配置された露光部（図示しない）でレーザー光３Ｃ、３Ｍ、３Ｙ、３Ｋにより、作成する各色の画像に対応した静電潜像が形成される。次に現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋにより潜像を現像してトナー像が形成される。
【０１６０】
現像部材４Ｃ、４Ｍ、４Ｙ、４Ｋは、それぞれＣ（シアン）、Ｍ（マゼンタ）、Ｙ（イエロー）、Ｋ（ブラック）のトナーで現像を行う現像部材で、４つの感光体１Ｃ、１Ｍ、１Ｙ、１Ｋ上で作られた各色のトナー像は転写紙上で重ねられる。
【０１６１】
転写紙７は給紙コロ８によりトレイから送り出され、一対のレジストローラ９で一旦停止し、上記感光体上への画像形成とタイミングを合わせて転写搬送ベルト１０に送られる。転写搬送ベルト１０上に保持された転写紙７は搬送されて、各感光体１Ｃ、１Ｍ、１Ｙ、１Ｋとの当接位置（転写部）で各色トナー像の転写が行われる。感光体上のトナー像は、転写ブラシ１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋに印加された転写バイアスと感光体１Ｃ、１Ｍ、１Ｙ、１Ｋとの電位差から形成される電界により、転写紙７上に転写される。
【０１６２】
そして４つの転写部を通過して４色のトナー像が重ねられた記録紙７は定着装置１２に搬送され、トナーが定着されて、図示しない排紙部に排紙される。また、転写部で転写されずに各感光体１Ｃ、１Ｍ、１Ｙ、１Ｋ上に残った残留トナーは、クリーニング装置５Ｃ、５Ｍ、５Ｙ、５Ｋで回収される。
【０１６３】
なお、図９の例では画像形成要素は転写紙搬送方向上流側から下流側に向けて、Ｃ（シアン）、Ｍ（マゼンタ）、Ｙ（イエロー）、Ｋ（ブラック）の色の順で並んでいるが、この順番に限るものでは無く、色順は任意に設定されるものである。また、黒色のみの原稿を作成する際には、黒色以外の画像形成要素（６Ｃ、６Ｍ、６Ｙ）が停止するような機構を設けることは本発明に特に有効に利用できる。更に、図９において帯電部材は感光体と当接しているが、両者の間に適当なギャップ（１０〜２００μｍ程度）を設けてやることにより、両者の摩耗量が低減できると共に、帯電部材へのトナーフィルミングが少なくて済み良好に使用できる。
【０１６４】
以上に示すような画像形成手段は、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、各々の電子写真要素はプロセスカートリッジの形でそれら装置内に組み込まれてもよい。プロセスカートリッジとは、感光体を内蔵し、他に帯電手段、露光手段、現像手段、転写手段、クリーニング手段、除電手段等の少なくとも１つを含んだ１つの装置（部品）である。
【０１６５】
【実施例】
以下、本発明を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。
まず、ブラッグ角２θの最大回折ピークが ２７．２°±０．２°にある結晶型のチタニルフタロシアニン顔料の具体的な合成例を述べる。
【０１６６】
（顔料作製例１）
１，３−ジイミノイソインドリン２９２部とスルホラン１８００部を混合し、窒素気流下でチタニウムテトラブトキシド２０４部を滴下する。滴下終了後、徐々に１８０℃まで昇温し、反応温度を１７０℃〜１８０℃の間に保ちながら５時間撹拌して反応を行った。反応終了後、放冷した後析出物を濾過し、クロロホルムで粉体が青色になるまで洗浄し、つぎにメタノールで数回洗浄し、さらに８０℃の熱水で数回洗浄した後乾燥し、粗チタニルフタロシアニンを得た。
【０１６７】
得られた熱水洗浄処理した粗チタニルフタロシアニン顔料のうち６０部を９６％硫酸１０００部に３〜５℃下撹拌、溶解し、濾過した。得られた硫酸溶液を氷水３５０００部中に撹拌しながら滴下し、析出した結晶を濾過、ついで洗浄液が中性になるまで水洗を繰り返し、チタニルフタロシアニン顔料の水ペーストを得た。
【０１６８】
この水ペーストにテトラヒドロフラン１５００部を加え、室温下で撹拌し、ペーストの濃紺色の色が淡い青色に変化したら、撹拌を停止し、直ちに減圧濾過を行った。濾過装置上で得られた結晶をテトラヒドロフランで洗浄し、顔料のウェットケーキ９８部を得た。これを減圧下（５ｍｍＨｇ）、７０℃で２日間乾燥して、チタニルフタロシアニン結晶７８部を得た。これを顔料１とする。
【０１６９】
顔料作製例１で得られた水ペーストの一部を８０℃の減圧下（５ｍｍＨｇ）で、２日間乾燥して、低結晶性チタニルフタロシアニン粉末を得た。
【０１７０】
上述のように得られた水ペーストの乾燥粉末と、顔料作製例１で得られたチタニルフタロシアニン結晶（顔料１）についてのＸ線回折スペクトルを以下に示す条件で測定した。
Ｘ線管球：Ｃｕ 電圧 ：４０ｋＶ 電流 ：２０ｍＡ
走査速度：１°／分 走査範囲：３°〜４０° 時定数：２秒
【０１７１】
水ペーストの乾燥粉末のＸ線回折スペクトルを第１０図に、顔料１のＸ線回折スペクトルを第１１図に示す。
【０１７２】
図１１より、顔料１は、２７．２゜に最大回折ピークを有し、更に９．４゜、９．６゜、２４．０゜に主要なピークを有し、かつ最も低角側の回折ピークとして７．３゜にピークを有し、７．４°以上９．４゜未満の範囲にピークを有さず、また２６．３゜にピークを有さない結晶型を有するチタニルフタロシアニン結晶であることが分かる。
【０１７３】
（比較例１）
下記組成の分散液を下に示す条件のビーズミリングにより作製した（これを分散液１とする）。
顔料作製例１で作製したチタニルフタロシアニン結晶（顔料１）２４０部
ポリビニルブチラール（積水化学製：ＢＸ−１） １６０部
２−ブタノン ３６００部
市販のビーズミル分散機（ＶＭＡ−ＧＥＴＺＭＡＮＮ ＧＭＢＨ製：ＤＩＳＰＥＲＭＡＴ ＳＬ、ローターの直径は５０ｍｍ、分散室容量は１２５ｍｌ）に直径０．５ｍｍのジルコニアボールを用い、ポリビニルブチラールを溶解した２−ブタノンおよび顔料を全て投入し、ローター回転数３０００ｒ．ｐ．ｍ．にて、３００分間分散を行った。
送液用のモーター回転数を目盛り５にセットした際の流量は１リッター／分であるが、上記条件の分散初期状態では、およそ８分間の間、０．３リッター／分に低下した。このままの状態でローター回転数を変えずに、３００分間分散を行った。
分散終了後、ビーズミル分散機よりミルベースを払い出し、更に１０３００部の２−ブタノンを投入し、希釈と同時に分散機に残ったミルベースをすべて払い出し、分散液を作製した。
【０１７４】
（実施例１）
比較例１において、循環流量が低下しないように送液用のモーター回転数を目盛り８に上げて、流量を０．９〜１リッター／分に保ちながら落として分散を行い、循環流量が１リッター／分以上になったら、徐々にモーター回転数を戻して、最終的に目盛り５に設定して分散を行った以外は、比較例１と同様に分散を行ない、分散液を作製した（これを分散液２とする）。
【０１７５】
（実施例２）
比較例１において、循環流量が低下しないように送液用のモーター回転数を目盛り７に上げて、流量を０．６〜０．８リッター／分に保ちながら落として分散を行い、循環流量が１リッター／分以上になったら、徐々にモーター回転数を戻して、最終的に目盛り５に設定して分散を行った以外は、比較例１と同様に分散を行ない、分散液を作製した（これを分散液３とする）。
【０１７６】
（実施例３）
比較例１において、循環流量が低下しないように送液用のモーター回転数を目盛り６に上げて、流量を０．４〜０．５リッター／分に保ちながら落として分散を行い、循環流量が１リッター／分以上になったら、徐々にモーター回転数を戻して、最終的に目盛り５に設定して分散を行った以外は、比較例１と同様に分散を行ない、分散液を作製した（これを分散液４とする）。
【０１７７】
（実施例４）
実施例１において、分散メディアを直径０．８ｍｍのジルコニアボールに変更した以外は、実施例１と同様に分散を行ない、分散液を作製した（これを分散液５とする）。
【０１７８】
（比較例２）
実施例１において、分散メディアを直径１．５ｍｍのジルコニアボールに変更した以外は、実施例１と同様に分散を行ない、分散液を作製した（これを分散液６とする）。
以上のように作製した分散液１〜６は、以下の評価を行った。結果を表１に示す。なお、表中の流量とは、循環流量が低下している際（分散初期状態における際の）の流量である（以下同じ）。
・平均粒径：
堀場製作所：ＣＡＰＡ７００にて体積平均粒径を評価した。
・粗大粒子の観察：
分散液をスライドガラスに塗布し、観察用のサンプルを作製した。続いて、市販の光学顕微鏡（５０〜１００倍）にて、塗膜の観察を行ない、粗大粒子の有無を観察した。
・Ｘ線回折スペクトル：
分散液を乾固し、粉末にしたものを前述と同様にＸ線回折スペクトルを測定した。
・成膜性の評価：
分散液を洗浄したアルミ板に浸漬塗工法により成膜して、塗膜の状態を観察した。
【０１７９】
【表１】

【０１８０】
なお、結晶の一部が結晶転移してしまった場合（比較例２）のＸ線回折スペクトルを図１２に示す。図中の矢印が、第１１図の結晶には認められない新たなピーク（２６．３゜）である。
【０１８１】
（実施例５）
実施例１の分散液に使用した溶媒を、２−ブタノンからｎ−酢酸ブチルに変更した以外は、実施例１と同様に分散液を作製した（これを分散液７とする）。
【０１８２】
（実施例６）
実施例１の分散液に使用した溶媒を、２−ブタノンからｎ−ブタノールに変更した以外は、実施例１と同様に分散液を作製した（これを分散液８とする）。
【０１８３】
（実施例７）
実施例１の分散液の組成を下記組成のものに変更した以外は、実施例１と同様に分散液を作製した（これを分散液９とする）。
顔料作製例１で作製したチタニルフタロシアニン結晶（顔料１）２４０部
ポリビニルブチラール（積水化学製：ＢＸ−１） １６０部
テトラヒドロフラン ３６００部
イオン交換水 ３６部
【０１８４】
（実施例８）
実施例７の分散液より、イオン交換水を除いた以外は、実施例７と同様に分散液を作製した（これを分散液１０とする）。
【０１８５】
（実施例９）
実施例１の分散液より、ポリビニルブチラールを除いた以外は、実施例１と同様に分散液を作製した（これを分散液１１とする）。
【０１８６】
以上のように作製した分散液７〜１１を、分散液１〜６の場合と同様に評価を行った。実施例１の結果と併せて表２に示す。
【０１８７】
【表２】

【０１８８】
表２から分かるように、分散溶媒として２−ブタノン（ケトン系溶媒）、ｎ−酢酸ブチル（エステル系溶媒）、テトラヒドロフラン（エーテル系溶媒）を用いた場合には良好な特性を有する分散液が得られたが、その他の溶媒であるｎ−ブタノール（アルコール系溶媒）を用いた場合には、やや分散安定性に劣る結果となった。
また、イオン交換水を添加しない場合や、バインダー樹脂を添加しない場合においては、結晶安定性に劣る場合が認められた。
【０１８９】
（顔料作製例２）
特開平１−２９９８７４号（特許第２５１２０８１号）公報の「実施例１」に記載の方法に準じて、顔料を作製した。すなわち、先の顔料作製例１で作製したウェットケーキを乾燥し、乾燥物２００ｇをポリエチレングリコール１０００ｇに加え、２００００ｇのガラスビーズと共に、サンドミルを行なった。結晶転移後、希硫酸、水酸化アンモニウム水溶液で順次洗浄し、乾燥して顔料を得た（これを顔料２とする）。
【０１９０】
（顔料作製例３）
特開平３−２６９０６４号（特許第２５８４６８２号）公報の「製造例１」に記載の方法に準じて、顔料を作製した。すなわち、先の顔料作製例１で作製したウェットケーキを乾燥し、乾燥物２００ｇをイオン交換水２０００ｇとモノクロルベンゼン２００ｇの混合溶媒中で１時間撹拌（５０℃）した後、メタノールとイオン交換水で洗浄し、乾燥して顔料を得た（これを顔料３とする）。
【０１９１】
（顔料作製例４）
特開平２−８２５６号（特公平７−９１４８６号）公報の「製造例」に記載の方法に準じて、顔料を作製した。すなわち、フタロジニトリル１９６ｇと１−クロロナフタレン１５００ｍｌを撹拌混合し、窒素気流下で四塩化チタン４４ｍｌを滴下する。滴下終了後、徐々に２００℃まで昇温し、反応温度を２００℃〜２２０℃の間に保ちながら３時間撹拌して反応を行なった。反応終了後、放冷し１３０℃になったところ熱時ろ過し、次いで１−クロロナフタレンで粉体が青色になるまで洗浄、次にメタノールで数回洗浄し、更に８０℃の熱水で数回洗浄した後、乾燥し顔料を得た（これを顔料４とする）。
【０１９２】
（顔料作製例５）
特開昭６４−１７０６６号（特公平７−９７２２１号）公報の「合成例１」に記載の方法に準じて、顔料を作製した。すなわち、α型ＴｉＯＰｃ２００部を食塩４００ｇおよびアセトフェノン２００ｇと共にサンドグラインダーにて１００℃にて１０時間結晶変換処理を行なった。これをイオン交換水及びメタノールで洗浄し、希硫酸水溶液で精製し、イオン交換水で酸分がなくなるまで洗浄した後、乾燥して顔料を得た（これを顔料５とする）。
【０１９３】
（顔料作製例６）
特開平１１−５９１９号（特許第３００３６６４号）公報の「実施例１」に記載の方法に準じて、顔料を作製した。すなわち、Ｏ−フタロジニトリル２０４部、四塩化チタン部７６部をキノリン５００部中で２００℃にて２時間加熱反応後、水蒸気蒸留で溶媒を除き、２％塩化水溶液、続いて２％水酸化ナトリウム水溶液で精製し、メタノール、Ｎ，Ｎ−ジメチルホルムアミドで洗浄後、乾燥し、チタニルフタロシアニンを得た。このチタニルフタロシアニン２００部を５℃の９８％硫酸４０部の中に少しずつ溶解し、その混合物を約１時間、５℃以下の温度を保ちながら攪拌する。続いて硫酸溶液を高速攪拌した８０００部の氷水中に、ゆっくりと注入し、析出した結晶を濾過する。結晶を酸が残量しなくなるまで蒸留水で洗浄し、ウエットケーキを得る。そのケーキをＴＨＦ１００００部中で約５時間攪拌を行ない、濾過、ＴＨＦによる洗浄を行ない乾燥後、顔料を得た（これを顔料６とする）。
【０１９４】
（顔料作製例７）
特開平３−２５５４５６号（特許第３００５０５２号）公報の「合成例２」に記載の方法に準じて、顔料を作製した。すなわち、先の顔料作製例１で作製したウェットケーキ４００部を塩化ナトリウム６００部とジエチレングリコール２８０部に混合し、８０℃の加熱下で自動乳鉢により６０時間ミリング処理を行なった。次に、この処理品に含まれる塩化ナトリウムとジエチレングリコールを完全に除去するために充分な水洗を行なった。これを減圧乾燥した後にシクロヘキサノン８０００部と直径１ｍｍのガラスビーズを加えて、３０分間サンドミルにより処理を行ない、顔料を得た（これを顔料７とする）。
【０１９５】
以上の顔料作製例２〜７で作製した顔料２〜７は、前記と同様の方法でＸ線回折スペクトルを測定し、それぞれの公報に記載のスペクトルと同様であることを確認した。表３にそれぞれのＸ線回折スペクトルと顔料作製例１で得られた顔料のＸ線回折スペクトルのピーク位置の特徴を示す。
【０１９６】
【表３】

【０１９７】
（実施例１０）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料２を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１２とする）。
【０１９８】
（実施例１１）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料３を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１３とする）。
【０１９９】
（実施例１２）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料４を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１４とする）。
【０２００】
（実施例１３）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料５を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１５とする）。
【０２０１】
（実施例１４）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料６を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１６とする）。
【０２０２】
（実施例１５）
実施例１で使用したチタニルフタロシアニン結晶（顔料１）の代わりに、それぞれ顔料７を用いた以外は、実施例１と同様に分散液を作製した（これらを分散液１７とする）。
以上のように作製した分散液１２〜１７は、実施例１の場合と同様に評価し、実施例１の結果と併せて表４に示す。
【０２０３】
【表４】

【０２０４】
表４から分かるように、顔料１とは結晶型の異なるチタニルフタロシアニン結晶を用いた場合においても、分散初期状態において循環流量が適正領域になるように、送液用部材の出力を制御する分散を行うことにより、結晶転移を起こさず、粗大粒子のない分散安定性の高い分散液を作製することが出来た。
【０２０５】
（感光体の作製）
感光体作製例１：
直径６０ｍｍのアルミニウムシリンダー（ＪＩＳ１０５０）に、下記組成の下引き層塗工液、電荷発生層塗工液、および電荷輸送層塗工液を、順次塗布・乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、１９μｍの電荷輸送層を形成し、積層感光体を作製した（これを感光体１とする）。
【０２０６】
［下引き層塗工液］
酸化チタン（ＣＲ−ＥＬ：石原産業社製） ７０部
アルキッド樹脂（ベッコライトＭ６４０１−５０−Ｓ
（固形分５０％）、大日本インキ化学工業製） １５部
メラミン樹脂（スーパーベッカミンＬ−１２１−６０
（固形分６０％）、大日本インキ化学工業製） １０部
２−ブタノン １００部
【０２０７】
［電荷発生層塗工液］
前記の分散液１を用いた。
【０２０８】
［電荷輸送層塗工液］
ポリカーボネート（ユーピロンＺ３００：三菱ガス化学社製） １０部
下記構造式の電荷輸送物質 ７部
【化１３】

テトラヒドロフラン ８０部
【０２０９】
感光体作製例２：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液２を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体２とする）。
【０２１０】
感光体作製例３：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液３を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体３とする）。
【０２１１】
感光体作製例４：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液４を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体４とする）。
【０２１２】
感光体作製例５：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液５を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体５とする）。
【０２１３】
感光体作製例６：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液６を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体６とする）。
【０２１４】
感光体作製例７：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液７を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体７とする）。
【０２１５】
感光体作製例８：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液８を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体８とする）。
【０２１６】
感光体作製例９：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液９を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体９とする）。
【０２１７】
感光体作製例１０：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１０を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１０とする）。
【０２１８】
感光体作製例１１：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１１を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１１とする）。
【０２１９】
感光体作製例１２：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１２を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１２とする）。
【０２２０】
感光体作製例１３：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１３を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１３とする）。
【０２２１】
感光体作製例１４：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１４を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１４とする）。
【０２２２】
感光体作製例１５：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１５を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１５とする）。
【０２２３】
感光体作製例１６：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１６を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１６とする）。
【０２２４】
感光体作製例１７：
感光体作製例１における電荷発生層塗工液として、分散液１の代わりに分散液１７を用いた以外は、感光体作製例１と同様に感光体を作製した（これを感光体１７とする）。
【０２２５】
（実施例１６〜３０および比較例３〜４）
以上のように作製した感光体１〜１８を市販の普通紙複写機（リコー製：ｉｍａｇｉｏＭＦ４５５０）に搭載した。ＡＣ電源として複写機本体外に別の電源を用意した。
画像露光光源は７８０ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）とした。
帯電部材としては、図６に示すような非接触近接配置方式の帯電ローラー（両端の非画像部には、厚さ５０μｍの絶縁テープを巻き付け、感光体表面と帯電ローラー表面の間に、５０μｍの空隙を有するように配置した）を用い、下記の帯電条件で画像を出力した。
帯電条件：
ＤＣバイアス：−９００Ｖ
ＡＣバイアス：２．３ｋＶ（ｐｅａｋｔｏｐｅａｋ）、周波数２ｋＨｚ
【０２２６】
書き込み率６％のチャートを用い、連続して５０００枚の印刷を行い、初期及び５０００枚後の画像を評価した。画像評価は、初期及び５０００枚後に白ベタ画像を出力し、地肌汚れの評価を行った（下記ランクで評価した）。また、４隅および中央に直径１ｃｍの黒丸（黒ベタ）を含むハーフトーン画像を初期及び５０００枚後に出力し画像評価を行った。
結果を表５に示す。
【０２２７】
【表５】

地汚れランク：
５：地汚れほとんど無し、４：わずかにあり、３：実使用限界レベル、２以下：実使用には耐えないレベル
【０２２８】
感光体作製例１８：
感光体作製例２における電荷輸送層塗工液を下記組成のものに変更した以外は、感光体作製例２と同様に感光体を作製した（これを感光体１８とする）。
［電荷輸送層塗工液］
下記組成の高分子電荷輸送物質
（重量平均分子量：約１４００００） １０部
【化１４】

下記構造の添加剤 ０．５部
【化１５】

テトラヒドロフラン １００部
【０２２９】
感光体作製例１９：
感光体作製例２における電荷輸送層の膜厚を１７μｍとし、電荷輸送層上に下記組成の保護層塗工液を塗布乾燥し、２μｍの保護層を設けた以外は感光体作製例２と同様に感光体を作製した（これを感光体１９とする）。
［保護層塗工液］
ポリカーボネート（ユーピロンＺ３００：三菱ガス化学社製） １０部
下記構造式の電荷輸送物質 ７部
【化１６】

アルミナ微粒子（比抵抗：２．５×１０^１２Ω・ｃｍ、
平均一次粒径：０．４μｍ） ４部
シクロヘキサノン ５００部
テトラヒドロフラン １５０部
【０２３０】
感光体作製例２０：
感光体作製例２における電荷輸送層の膜厚を１７μｍとし、電荷輸送層上に下記組成の保護層塗工液を塗布乾燥し、２μｍの保護層を設けた以外は感光体作製例２と同様に感光体を作製した（これを感光体２０とする）。
［保護層塗工液］
下記構造式の高分子電荷輸送物質
（重量平均分子量：約１４００００） １７部
【化１７】

アルミナ微粒子（比抵抗：２．５ｘ１０^１２Ω・ｃｍ、
平均一次粒径：０．４μｍ） ４部
シクロヘキサノン ５００部
テトラヒドロフラン １５０部
【０２３１】
感光体作製例２１：
感光体作製例２０における保護層塗工液中のアルミナ微粒子を以下のものに変更した以外は、感光体作製例２０と同様に感光体を作製した（これを感光体２１とする）。
酸化チタン微粒子（比抵抗：１．５×１０^１０Ω・ｃｍ、
平均一次粒径：０．５μｍ） ４部
【０２３２】
感光体作製例２２：
感光体作製例２０における保護層塗工液中のアルミナ微粒子を以下のものに変更した以外は、感光体作製例２０と同様に感光体を作製した（これを感光体２２とする）。
酸化錫−酸化アンチモン粉末 ４部
（比抵抗：１０^６Ω・ｃｍ、平均１次粒径０．４μｍ）
【０２３３】
感光体作製例２３：
感光体作製例２における電荷輸送層塗工液を下記組成のものに変更した以外は、感光体作製例２と同様に感光体を作製した（これを感光体２３とする）。
［電荷輸送層塗工液］
ポリカーボネート（ユーピロンＺ３００：三菱ガス化学社製） １０部
下記構造式の電荷輸送物質 ７部
【化１８】

トルエン ８０部
【０２３４】
感光体作製例２４：
感光体作製例２における電荷輸送層塗工液を下記組成のものに変更した以外は、感光体作製例２と同様に感光体を作製した（これを感光体２４とする）。
［電荷輸送層塗工液］
ポリカーボネート（ユーピロンＺ３００：三菱ガス化学社製） １０部
下記構造式の電荷輸送物質 ７部
【化１９】

塩化メチレン ８０部
【０２３５】
感光体作製例２５：
感光体作製例２におけるアルミニウムシリンダー（ＪＩＳ１０５０）を以下の陽極酸化皮膜処理を行ない、次いで下引き層を設けずに、感光体作製例２と同様に電荷発生層、電荷輸送層を設け、感光体を作製した（これを感光体２５とする）。
［陽極酸化皮膜処理］
支持体表面の鏡面研磨仕上げを行ない、脱脂洗浄、水洗浄を行なった後、液温２０゜Ｃ、硫酸１５ｖｏｌ％の電解浴に浸し、電解電圧１５Ｖにて３０分間陽極酸化皮膜処理を行なった。更に、水洗浄を行なった後、７％の酢酸ニッケル水溶液（５０゜Ｃ）にて封孔処理を行なった。その後純水による洗浄を経て、７μｍの陽極酸化皮膜が形成された支持体を得た。
【０２３６】
（実施例３１〜３９）
以上のように作製した感光体２、１８〜２５を市販の普通紙複写機（リコー製：ｉｍａｇｉｏＭＦ４５５０）に搭載した。ＡＣ電源として複写機（ポリゴン・ミラーによる画像書き込み）とした。
帯電部材としては、図６に示すような非接触近接配置方式の帯電ローラー（両端の非画像部には、厚さ５０μｍの絶縁テープを巻き付け、感光体表面と帯電ローラー表面の間に、５０μｍの空隙を有するように配置した）を用い、下記の帯電条件で画像を出力した。
帯電条件：
ＤＣバイアス：−９００Ｖ
ＡＣバイアス：２．３ｋＶ（ｐｅａｋｔｏｐｅａｋ）、周波数２ｋＨｚ
【０２３７】
書き込み率６％のチャートを用い、連続して１００００枚の印刷を行い、初期及び１００００枚後の画像を評価した。画像評価は、初期及び１００００枚後に白ベタ画像を出力し、地肌汚れの評価を行った（下記ランクで評価した）。また、４隅および中央に直径１ｃｍの黒丸（黒ベタ）を含むハーフトーン画像を初期及び１００００枚後に出力し画像評価を行った。
結果を表６に示す。
【０２３８】
【表６】

地汚れランク：
５：地汚れほとんど無し、４：わずかにあり、３：実使用限界レベル、２以下：実使用には耐えないレベル
【０２３９】
（実施例４０）
実施例３１の評価において、帯電条件を以下の条件に変更した以外は、実施例３１と同様に評価を行った。結果を表７に示す。
帯電条件：
ＤＣバイアス：−１７００Ｖ（感光体表面の未露光部電位が−９００Ｖになるように設定）
【０２４０】
（実施例４１）
実施例４０の評価において、使用する帯電ローラーを接触方式（ローラー材質等は同じであり、両端の絶縁テープを巻き付けない）に変更し、下記の帯電条件で画像を出力した。結果を表７に示す。
帯電条件：
ＤＣバイアス：−１６５０Ｖ（感光体表面の未露光部電位が−９００Ｖになるように設定）
【０２４１】
（実施例４２）
実施例４０の評価において、使用する帯電ローラーを接触方式（ローラー材質等は同じであり、両端の絶縁テープを巻き付けない）に変更し、下記の帯電条件で画像を出力した。結果を表７に示す。
帯電条件：
ＤＣバイアス：−９００Ｖ
ＡＣバイアス：２．３ｋＶ（ｐｅａｋｔｏｐｅａｋ）、周波数２ｋＨｚ
【０２４２】
（実施例４３）
実施例３１の評価において、絶縁テープの厚みを変えて、空隙を１５０μｍに変更した以外は実施例３１と同様に評価を行った。結果を表７に示す。
【０２４３】
（実施例４４）
実施例３１の評価において、絶縁テープの厚みを変えて、空隙を２５０μｍに変更した以外は実施例３１と同様に評価を行った。結果を表７に示す。
【０２４４】
（実施例４５）
実施例３１の評価において、使用する帯電部材としてスコロトロンチャージャーを用い、評価を行った。この際、試験に用いる複写機はスコロトロンチャージャーを搭載できるように改造を施した。
帯電条件：
ＤＣバイアス：−６．５ｋＶ
【０２４５】
【表７】

地汚れランク：
５：地汚れほとんど無し、４：わずかにあり、３：実使用限界レベル、２以下：実使用には耐えないレベル
【０２４６】
感光体作製例２６：
感光体作製例１において使用した支持体を、直径３０ｍｍのアルミニウムシリンダー（ＪＩＳ１０５０）に変更した以外は感光体作製例１と同様に感光体を作製した（これを感光体２６とする）。
【０２４７】
感光体作製例２７：
感光体作製例２６において、使用した分散液１の代わりに分散液２を用いた以外は、感光体作製例２６と同様に感光体を作製した（これを感光体２７とする）。
【０２４８】
感光体作製例２８：
感光体作製例２６において、使用した分散液１の代わりに分散液７を用いた以外は、感光体作製例２６と同様に感光体を作製した（これを感光体２８とする）。
【０２４９】
（実施例４６および比較例５、６）
以上のように作製した感光体２６〜２８を、図８に示すような画像形成装置用カートリッジに装着し、図９に示すようなタンデム方式のフルカラー画像形成装置に搭載し（すべての画像形成要素に同じ感光体を搭載した）、画像露光光源を７８０ｎｍの半導体レーザー（ポリゴン・ミラーによる画像書き込み）として、帯電部材として第６図に示すような帯電ローラーの両端部に厚さ５０μｍの絶縁テープを巻き付けた近接配置用の帯電部材（感光体と帯電部材表面間の空隙が５０μｍ）を用い、下記の帯電条件で画像を出力した。
帯電条件：
ＤＣバイアス：−８００Ｖ
ＡＣバイアス：２．２ｋＶ（ｐｅａｋ ｔｏ ｐｅａｋ）、周波数：１．５ｋＨｚ
【０２５０】
書き込み率６％のフルカラーチャートを用い、連続して５０００枚の印刷を行い、初期及び５０００枚後の画像を評価した。画像評価は、初期及び５０００枚後に白ベタ画像を出力し、地肌汚れの評価を行った。また、色再現性を評価するチャートにて、５０００枚後の色再現性を評価した。結果を表８に示す。
【０２５１】
【表８】

地汚れランク：
５：地汚れほとんど無し、４：わずかにあり、３：実使用限界レベル、２以下：実使用には耐えないレベル
【０２５２】
続いて、本発明で使用するチタニルフタロシアニン結晶の特徴であるブラッグ角θの最低角ピークである７．３°について、公知材料の最低角７．５°と同一であるか否かについて検証する。
【０２５３】
（顔料作製例８）
顔料作製例１における結晶変換溶媒を塩化メチレンから２−ブタノンに変更した以外は、合成例１と同様に処理を行ない、チタニルフタロシアニン結晶を得た。
図１１の場合と同様に、顔料作製例８で作製したチタニルフタロシアニン結晶のＸ線回析スペクトルを測定した。これを図１３に示す。図１３より、顔料作製例８で作製されたチタニルフタロシアニン結晶のＸ線回析スペクトルにおける最低角は、合成例１で作製されたチタニルフタロシアニンの最低角（７．３°）とは異なり、７．５°に存在することが判る。
【０２５４】
（測定例１）
顔料作製例１で得られた顔料（最低角７．３°）に特開昭６１−２３９２４８号公報に記載の顔料（最大回折ピークを７．５°に有する）と同様に作製したものを３重量％添加し、乳鉢で混合して、先程と同様にＸ線回折スペクトルを測定した。測定例１のＸ線回折スペクトルを図１３に示す。
【０２５５】
（測定例２）
顔料作製例８で得られた顔料（最低角７．５°）に特開昭６１−２３９２４８号公報に記載の顔料（最大回折ピークを７．５°に有する）と同様に作製したものを３重量％添加し、乳鉢で混合して、前記と同様にＸ線回折スペクトルを測定した。測定例２のＸ線回折スペクトルを図１５に示す。
【０２５６】
図１４のスペクトルにおいては、低角側に７．３°と７．５°の２つの独立したピークが存在し、少なくとも７．３°と７．５°のピークは異なるものであることが判る。一方、図１３のスペクトルにおいては、低角側のピークは７．５°のみに存在し、図１４のスペクトルとは明らかに異なっている。
以上のことから、本願発明のチタニルフタロシアニン結晶における最低角ピークである７．３°は、公知のチタニルフタロシアニン結晶における７．５°のピークとは異なるものであることが判る。
【０２５７】
【発明の効果】
本発明に依れば、結晶安定性が低く、微粒子化が困難であるチタニルフタロシアニン結晶の分散に鑑み、循環方式のビーズミル分散装置を用い、循環分散初期の分散室出口側の顔料目詰まりによる循環流量の低下を防ぎ、流量を所定範囲に保つために、分散室に送液するポンプ等の循環部材の出力を定常状態よりも大きくする特定の条件化で分散を行うことにより、結晶安定性と微粒子化のトレード・オフの関係を解消することが出来た。この結果、結晶安定性が高く（結晶転移の少ない）、粒子サイズの小さなチタニルフタロシアニン結晶を含む分散液の製造方法が提供される。この分散液は、保存安定性にも富み、成膜性が良好であるだけでなく、チタニルフタロシアニン結晶特有の特性を維持したままの状態で微粒子化が施される。このため、この分散液を用いて作製される感光体は、高感度を失うことなく、繰り返し使用によっても帯電性の低下と残留電位の上昇を生じない安定な電子写真感光体である。また、繰り返し使用によっても異常画像の発生の少ない電子写真感光体が提供される。
更に、高速プリントが可能で、異常画像の発生の少ない、安定な画像形成装置および画像形成装置用プロセスカートリッジが提供される。
【図面の簡単な説明】
【図１】本発明の分散液作製に用いられるビーズミル分散装置の概略図。
【図２】図１に示すビーズミル分散装置の分散室２の内部を示す図。
【図３】本発明の電子写真感光体の一例の構成例を示す図。
【図４】本発明の電子写真感光体の別の構成例を示す図。
【図５】本発明の画像形成プロセスを説明するための図。
【図６】画像形成装置の帯電部剤側にギャップ形成部材を配置した近接帯電機構の一例を示す図。
【図７】本発明の画像形成プロセスの別の例を説明するための図。
【図８】画像形成装置用プロセスカートリッジの１例を示す図。
【図９】カラー画像形成装置を説明するための概略図。
【図１０】顔料作成例１で得られた水ペーストの乾燥粉末のＸ線回析スペクトル。
【図１１】顔料１のＸ線回析スペクトル。
【図１２】比較例２で得られたチタニルフタロシアニン結晶のＸ線回析スペクトル。
【図１３】顔料作製例８で得られたチタニルフタロシアニン結晶のＸ線回析スペクトル。
【図１４】測定例１で得られたチタニルフタロシアニン結晶のＸ線回析スペクトル。
【図１５】測定例２で得られたチタニルフタロシアニン結晶のＸ線回析スペクトル。
【符号の説明】
（図１および図２において）
１ モーター
２ 分散室
３ 流量計
４ 循環タンク
５ 循環ポンプ
６ 配管
７ 分散室固定台
１０ 分散メディア
１１ スリット
１２ 循環出口側配管
１３ 分散室の壁
１４ ローター
１５ 循環入り口側配管
１６ モーター
（図３および図４において）
３１ 導電性支持体
３５ 電荷発生層
３７ 電荷輸送層
３９ 保護層
（図６において）
２９ 感光体
３０ 帯電ローラー
３１ ギャップ形成部材
３２ 金属シャフト
３３ 画像形成領域
３４ 非画像形成領域
（図９において）
１Ｃ、１Ｍ、１Ｙ、１Ｋ 感光体
２Ｃ、２Ｍ、２Ｙ、２Ｋ 帯電部材
３Ｃ、３Ｍ、３Ｙ、３Ｋ レーザー光
４Ｃ、４Ｍ、４Ｙ、４Ｋ 現像部材
５Ｃ、５Ｍ、５Ｙ、５Ｋ クリーニング部材
６Ｃ、６Ｍ、６Ｙ、６Ｋ 画像形成要素
１０ 転写搬送ベルト
１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋ 転写ブラシ
１２ 定着装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a dispersion using titanyl phthalocyanine crystals. Further, the present invention relates to an electrophotographic photosensitive member manufactured using the dispersion liquid prepared as described above, an image forming apparatus using the electrophotographic photosensitive member, and a process cartridge for the image forming apparatus.
In detail, a method for preparing a dispersion containing a titanyl phthalocyanine crystal having excellent dispersibility and crystal stability and good handling properties, and also having excellent charging potential stability even after repeated use, with little increase in residual potential, The present invention relates to an electrophotographic photoreceptor with less occurrence of abnormal images such as stains, an image forming apparatus using the electrophotographic photoreceptor, and a process cartridge for the image forming apparatus.
[0002]
[Prior art]
Organic pigments have long been used as fillers for paints. In particular, the richness of the color is an advantage not found in inorganic pigments. In recent years, as an application example of an organic pigment, various materials have been produced since they have been spotlighted as materials for organic photoelectric conversion devices.
An electrophotographic photoreceptor containing an organic pigment is generally formed by a wet method. In particular, the dip coating method suitable for mass production is the majority of the method for producing a drum-shaped photoreceptor. The dip coating method is most suitable for mass product type production because the apparatus and method are simple, but even when a small number of coatings are applied, a minimum required amount of coating liquid is required. The minimum required amount is extremely large as compared with other coating methods, for example, a spraying method, a nozzle coating method such as a nozzle coating method.
[0003]
It is not an exaggeration to say that the quality of a coating film formed by a wet film formation method is substantially influenced by the quality of a dispersion liquid containing a pigment. The quality of the dispersion depends on the dispersibility of the pigment. Therefore, a good dispersion is one in which the pigment is sufficiently dispersed in the vehicle and the dispersion state is maintained for a long time. Various methods for dispersing an organic pigment have been proposed for producing such a dispersion, but there are some restrictions when producing a large amount of dispersion. That is, in a ball mill, a vibration mill, or the like, the capacity of the pot determines the amount that can be manufactured. From such a viewpoint, a dispersion system having a part (dispersion chamber) having a dispersibility in a circulation system has been proposed as a dispersion system capable of producing a large amount of dispersion liquid in one batch [Japanese Patent Laid-Open No. 2000-181104]. Gazette (Patent Document 1)].
[0004]
Such systems are generally designed to have a small dispersing chamber volume for large stock tanks. This is for the purpose of compacting the system, saving energy, and reducing the number of distributed media used in the distribution room.
In such a dispersing method, a bead mill type dispersing system using small-diameter beads in a dispersing chamber is often used in order to reduce the pigment particle diameter after dispersion.
[0005]
As the diameter of the beads used here becomes smaller as the diameter becomes smaller, the attained particle diameter of the dispersed pigment becomes smaller. Therefore, generally, a bead having a diameter of 1 mm or less is used, and a bead having a diameter of 0.5 mm or less is preferably used [ JP 2001-290292 A (Patent Document 2)]. However, if the diameter is too small, the abrasion of the beads increases, or the target pigment particles before dispersion need to be reduced, or the handling during maintenance deteriorates. Beads (dispersion media) are used.
[0006]
In the preparation of a dispersion, such small-diameter beads are made to exist in a dispersion chamber, and pigment particles are dispersed by rotation of a rotor. At the same time, it is necessary to pass a liquid containing a pigment through the dispersion chamber. In a dispersion system other than the circulation system, the dispersion medium does not flow out of the dispersion chamber (for example, a pot of a ball mill), but in the circulation system dispersion machine (beads mill), the dispersion medium is circulated together with the circulation of the liquid containing the pigment. It may be washed out of the dispersion chamber. In order to prevent such a dispersion medium from flowing out, a filter, a mesh, or the like smaller than the dispersion medium diameter is installed at the outlet side of the dispersion chamber.
[0007]
The pore size of this filter or the like is set to about half of the minimum bead size to be used in consideration of the bead size distribution and the like. In the case where the diameter of the dispersion medium exceeds 1 mm, there is not much problem because the pore diameter is about 500 μm, but when the diameter of the bead becomes smaller than about 1 mm (preferably 0.5 mm). In the initial stage of dispersion, pigment particles at a coarsely pulverized level may cause clogging. Except in extreme cases, the clogged pigment gradually becomes finer in the dispersion chamber, eventually becomes smaller than the filter pore size, and is discharged from the dispersion chamber. However, the pigment clogged on the outlet side stays in the dispersing chamber for a longer time than the predetermined time according to the flow rate, so that energy larger than the target dispersing energy is given, Results in excessive stress.
[0008]
Even in such a case, if an organic pigment having a very stable crystal form is used, only the particle size will be reduced. By further dispersing, the particle size of the entire pigment will eventually be averaged (uniform). ). However, when using an organic pigment whose crystal form stability is not so high, the crystal form changes to the stable form, and the desired crystal form is not maintained. As a result, the color of the pigment in the paint, or Various properties of the pigment will be changed.
[0009]
Even though organic pigments are represented by the same structural formula, there are pigments having many crystal forms (polymorphs). Such pigments have different molecular arrangements in the crystal as an aggregate of molecules, even if they have the same chemical structural formula at the molecular level. In such a case, the color (absorption spectrum), particle morphology, and physical properties (characteristics) of the pigment often change extremely depending on the crystal form. If the absorption spectrum or the particle morphology changes as described above, for example, when used as a paint, the tint changes, and a coating film having a desired color cannot be formed. Further, in the case where an organic pigment is used as a functional material, if the physical property values are different, an element or the like using the same may not exhibit a desired function.
[0010]
The titanyl phthalocyanine crystal used in the present invention is a typical polymorphic organic pigment. Among them, there are cases where specific characteristics (showing extremely high photocarrier generation ability when used as a charge generating substance of a photoreceptor) are exhibited only when a specific crystal type is exhibited. Although the method and conditions for dispersal while maintaining the pattern are necessary, there are not many examples studied. In particular, a titanyl phthalocyanine crystal having a maximum diffraction peak at least 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to characteristic X-ray (wavelength 1.542 °) of CuKα is used for an electrophotographic photosensitive member. Although it has a very high photocarrier generation efficiency as a charge generation material, it is easily metastable because it is in a metastable state as a crystalline state.
[0011]
When an excessive stress is applied to this crystal, the crystal easily transitions to a titanyl phthalocyanine crystal having a maximum diffraction peak at 26.3 ° as a diffraction peak at a Bragg angle of 2θ, and this crystal has a much higher carrier generation efficiency than the previous crystal. Since the crystal is low, even if only a part of the crystal is displaced, if this is used as a charge generation material of the photoreceptor, problems such as a decrease in photosensitivity and an increase in residual potential upon repeated use occur.
[0012]
Such a problem is attributed to the problem of crystal transition caused by clogging of the pigment at the circulation outlet side of the dispersion chamber, but using a circulation type bead mill disperser and using a small-diameter dispersion medium. It is an unavoidable problem in some cases.
[0013]
In connection with such a point, Japanese Patent Application Laid-Open No. 2000-126638 (Patent Document 3) discloses a technique in which pigment particles to be subjected to wet dispersion are previously reduced to の or less the diameter of a dispersion medium. In the case of this method, since a pigment finer than the diameter of the dispersion medium is used, clogging of the pigment on the outlet side of the dispersion chamber may be reduced. However, when the pigment stays in the dispersion chamber for a predetermined time or more, there is a possibility that crystal transition occurs. In addition, it is necessary to dry-disperse the pigment particles in advance, or to use a sieve or the like to make the particle size uniform, which causes loss of the pigment, increases the cost due to an increase in the number of steps, or uses a fine pigment. It is not always suitable for mass production because of poor handling.
[0014]
As described above, when performing bead mill dispersion in a circulation system using a small-diameter dispersion medium, it is possible to easily achieve both the stability of crystal form and the miniaturization of particles in a short time without substantially reducing the dispersion efficiency. There was no way to solve it.
[0015]
[Patent Document 1]
JP 2000-181104 A
[Patent Document 2]
JP 2001-290292 A
[Patent Document 3]
JP-A-2000-1226638
[0016]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a dispersion containing titanyl phthalocyanine crystals having high crystal stability (less crystal transition) and small particle size. Specifically, an object is to efficiently produce a large amount of dispersion liquid by a simple method using a compact apparatus and a simple method.
Another object of the present invention is to provide a stable electrophotographic photoreceptor which does not cause a decrease in chargeability and a rise in residual potential even when repeatedly used without losing high sensitivity. Another object of the present invention is to provide an electrophotographic photoreceptor in which an abnormal image is less likely to occur even when repeatedly used.
Still another object of the present invention is to provide an image forming apparatus and a process cartridge for the image forming apparatus, which can perform high-speed printing, generate less abnormal images, and form stable images.
[0017]
[Means for Solving the Problems]
The present inventor has studied in view of the problems of the prior art, and as a result, in order to prevent the crystal transition that occurs when the pigment staying in the dispersion chamber for a longer time than a predetermined time is given an excessive dispersion energy, the dispersion chamber as described above is used. It has been found that it is important to eliminate clogging at the outlet or to set a condition that does not cause crystal transition even if clogging occurs to some extent.
[0018]
In the former method, all the pigment particles need to be smaller than the pore size of the filter or the like at the outlet of the dispersion chamber, and as described in JP-A-2000-12638, pre-dispersion by a dry method, sieving, etc. Sorting is required, which is not preferable because the number of steps increases. From this, the inventor selected the latter method and searched for a method for realizing it.
As a result, if clogging occurs at the outlet of the dispersion chamber, the required flow rate cannot be obtained even if the liquid is sent by a pump or the like so that a constant flow rate flows. Was found to be secured. It was also confirmed that the pigment particles that had passed through the filter at the outlet of the dispersion chamber even once did not cause clogging again. Depending on the size of the pigment to be dispersed, the amount of the pigment used, and the like, the time during which the flow rate decreases is approximately several minutes. During this time, the pigment staying in the dispersing chamber can continue to give a dispersing stress, and it is considered that the crystal transition is promoted, and the pigment is sent to the dispersion so as not to cause such a decrease in the flow rate. It has been found that the crystal transition can be prevented by increasing the output of the liquid member (for example, a circulation pump or a liquid feed stirrer) and keeping the circulation flow rate substantially constant.
[0019]
Continuing dispersion with the output of the liquid-feeding member large after this is not a problem if the margin of durability of the dispersing device or the liquid-feeding member is very large. Since it is used in a large area, the stress of the liquid sending section increases. Further, since a large pressure is applied to the filter at the outlet of the dispersion chamber, it is difficult to operate for a long time. Therefore, when the pressure decreases and the flow rate falls within a certain range, it is preferable to quickly set the output of the liquid sending section and continue the circulation and dispersion.
In order to make the above method concrete, the present inventor has eliminated the drawbacks of the circulating dispersion system generally used in recent years, found a stable dispersion production method, and completed the present invention. is there.
[0020]
Further, the present invention is an invention made for the purpose of improving the problems in producing a dispersion using a circulation type bead mill disperser capable of producing a large amount of a dispersion with a compact dispersion apparatus. . Specifically, the present invention solves a problem that occurs when a dispersion medium having a smaller diameter is used in order to make pigment particles contained in a dispersion liquid after dispersion finer.
[0021]
Incidentally, in an electrophotographic photoreceptor using an organic pigment as a charge generating substance, various characteristics are affected by the size of the charge generating substance particles in the photosensitive layer. For example, in the photocarrier generation process, if the size of the charge generation material particles is large before transferring the photocarriers generated by the charge generation material to the charge transport material, the probability of deactivation inside the particles increases. In addition, when the photocarrier is transferred to the charge transport material, if the pigment particles are large, the surface area is inevitably reduced, the contact amount between the two is reduced, and the carrier injection efficiency is reduced. Further, when the particle size of the charge generating substance is large, the probability of coating film defects in the photosensitive layer (charge generating layer) increases, and image defects based on this are likely to occur.
[0022]
For these reasons, it is desired to reduce the particle size of the charge generation substance in the photosensitive layer (charge generation layer) as much as possible. Since the photosensitive layer (charge generation layer) is usually formed by a wet coating method, in order to reduce the particle size of the charge generation substance in the photosensitive layer, the particle size of the charge generation substance in the coating dispersion forming the photosensitive layer is reduced. Need to be smaller.
[0023]
As described above, various dispersion methods have been proposed in order to reduce the particle size of the charge generating substance in the dispersion for coating the photosensitive layer (charge generating layer). A major issue is how to grind and disperse the secondary particles, which are structures, into primary particles. In these methods, the dispersion energy is increased, the dispersion time is extended, etc., so that the primary particles are made as close as possible.However, the primary particle size is determined at the stage of synthesizing the charge generation material, It is difficult to make the particles smaller than the primary particle size by a usual method.
[0024]
On the other hand, there has been proposed a dispersion method capable of giving a stronger dispersion energy than a method such as ball milling which has been used for a long time, and a method of further crushing primary particles has been developed in recent years. In such a case, even if the primary particles are somewhat large, the crystal itself is pulverized by the huge dispersion energy, thereby reducing the particle size of the charge generating substance. Such a method can be said to be very suitable for a material having a high crystal stability of the charge generating substance used.
[0025]
However, in the case of an organic charge generation material, even in the case of materials represented by the same chemical structural formula, only a specific crystal type often exerts a specific function. Such a specific crystal type may be easily changed by a simple physical or mechanical stress in addition to the chemical stress. When such a material is used, as described above, giving excessive dispersion energy to pulverize the primary particles themselves changes the crystal form before the action of pulverizing the particles. Will happen. As a result, there are many cases in which a material that exhibits a specific function is changed to a material that does not sufficiently exhibit the function, even though the material is intended to be used.
[0026]
The titanyl phthalocyanine crystal used in the present invention is a polymorphic material, and a crystal type having a particularly high photocarrier generation efficiency has a diffraction peak (±±) at a Bragg angle 2θ with respect to CuKα characteristic X-ray (wavelength 1.542 °). 0.2 [deg.]), Only crystals having a maximum diffraction peak at least at 27.2 [deg.], And other crystal-type materials also have a function as a charge generating material, but have a high speed required by current electrophotographic processes. However, it does not have characteristics satisfying high stability, high stability when repeatedly used, and reduction in diameter of the photoreceptor. Therefore, it can be said that the crystal type is a specific crystal type.
[0027]
However, the titanyl phthalocyanine crystal having the maximum diffraction peak at least at 27.2 ° is a metastable state as a titanyl phthalocyanine crystal, and is a material having low crystal stability. Therefore, when the mechanical and physical stresses are excessively applied as described above, the crystal is transformed into another crystal type which is a stable crystal type. As described above, titanyl phthalocyanine crystal having a high function as a charge generating substance, but when applied to an electrophotographic photoreceptor, there is a trade-off relationship between finer particles and crystal stability. There was no easy solution to this.
[0028]
In order to solve the above-mentioned problems, the present inventor tried to analyze the pulverization and dispersion steps of titanyl phthalocyanine crystals, and obtained the following knowledge.
[0029]
(1) Excessive dispersion energy causes crystal transition to progress
That is, in the step of dispersing the titanyl phthalocyanine crystal, when dispersing to the target particle size, it is necessary to pulverize and disperse particles larger than that, but if excessive dispersion energy is given, Excess energy becomes the energy of the crystal transition.
[0030]
{Circle around (2)} The temperature rise at the time of dispersion is to promote the crystal transition.
That is, in the step of dispersing the titanyl phthalocyanine crystal, the energy is converted into an energy that causes a crystal transition even at a partial temperature rise. Therefore, in a portion where dispersion energy is applied to the titanyl phthalocyanine crystal in the dispersing device, a sufficient cooling mechanism is required when a temperature rise is expected.
[0031]
In consideration of the above two points, in the method of dispersing a dispersion liquid in two directions described in Japanese Patent Application Laid-Open No. 4-372955 and colliding the dispersion liquid, it is necessary to suppress the application of excessive energy. And the temperature of the dispersion is unavoidable even if the entire apparatus is cooled. This shows that this method is disadvantageous. Also, when a high-pressure homogenizer as described in JP-A-5-188614 is used, it is difficult to suppress the temperature rise of the dispersion as in the case of the above-described dispersing apparatus, and this method is not advantageous. Furthermore, since the ball mill type dispersion apparatus conventionally used rotates the pot directly, it is basically difficult to provide a cooling mechanism. Therefore, this method is not an advantageous method.
[0032]
On the other hand, in the bead mill method used in the present invention, the dispersion chamber itself can be cooled, and the temperature of the dispersion liquid can be prevented from being raised at all by controlling the size and the number of rotations of the dispersion chamber. In addition, by using a circulation type bead mill dispersing apparatus as described later, it is possible to suppress a slight temperature rise by sufficiently cooling the circulation tank. In addition, it is possible to make the scale relatively large by this method.
From the above points, it can be said that the bead mill method is the most appropriate dispersion method as the dispersion method.
[0033]
Furthermore, the present inventor tried to analyze the process of pulverizing and dispersing the titanyl phthalocyanine crystal when the bead mill method was used, and obtained the following knowledge.
[0034]
(1) The ultimate particle size after dispersion is determined by the size of the dispersion media.
In other words, the larger the diameter of the dispersion media used for dispersion, the higher the ability to grind coarse particles of titanyl phthalocyanine crystal (aggregated primary particles). However, since a dispersion method such as a bead mill is originally a method having a high crushing ability, it is not always necessary to help the size (that is, weight) of the dispersion medium. Rather, it is important how much dispersion media can be packed per predetermined volume (how to reduce the porosity below). It was found that the smaller the porosity, the smaller the size of the dispersed titanyl phthalocyanine particles. Practically, if the diameter of the dispersion medium is 1 mm or less (preferably 0.5 mm or less), it can be sufficiently used. However, the smaller the size, the more the abrasion of the dispersing medium becomes, and the handling such as cleaning becomes very complicated. For this reason, there is a lower limit and dispersing media less than 0.1 mm should not be used.
[0035]
(2) When using small-diameter dispersion media, pigment clogging at the exit side of the dispersion chamber must be large.
In the case of performing circulation type dispersion, the flow-out is prevented by providing a filter or mesh of an appropriate size so that the dispersion medium does not flow out of the dispersion chamber. However, the smaller the diameter of the dispersing media, the smaller the pore size must be, and in this case, the probability that undispersed pigment particles are caught by the filter and cause clogging increases. When clogging occurs, when a constant pressure is applied by a circulation pump or the like to circulate the liquid, a pressure loss occurs, and the circulation flow rate is reduced (in severe cases, circulation cannot be performed). As a result, the pigment particles that cannot escape from the dispersion chamber stay in the dispersion chamber for a time longer than the passage time of the dispersion chamber according to the circulation amount, and receive an excessive dispersion stress. As a result, there is a possibility that a pigment having low crystal stability may cause crystal transition.
[0036]
(3) The crystal transition depends on the time spent in the dispersion chamber.
Assuming a state where the dispersion chamber is clogged, an experiment was conducted in which the dispersion was carried out in a non-circulating state, and as a result, when the dispersion was performed at about the rotation speed of the rotor to perform the circulating dispersion, the crystallization occurred in a relatively short time. Metastasis was found to occur. Also, from experiments in which the pigment concentration in the dispersion chamber was changed, the decrease was more remarkable as the concentration was higher, and as a result of clogging, the pigment sent to the dispersion chamber one after another caused the pigment in the dispersion chamber to change from the steady state. It was found that the higher the concentration, the faster the crystal transition. Further, in an experiment in which the dispersion time was changed, it was found that the dispersion time dependency was high and the crystal transition amount changed almost linearly with the dispersion time. For this reason, it is important to make the flow rate almost constant and to make the passage time of the dispersion chamber uniform, and to make the circulation flow rate almost constant, increase the liquid sending amount (output) by the circulation pump or the like, so that the clogging is likely. It was confirmed that most of the natural pigments flowed out into the dispersion chamber without convection. It was understood that the clogging situation can be grasped by monitoring this flow rate change.
[0037]
Based on these examinations and findings, the above-mentioned problem is achieved by the following (1) to (22).
[0038]
(1) In a method of preparing a dispersion containing titanyl phthalocyanine crystals by a circulation type bead mill dispersion apparatus using a dispersion medium having a diameter of 1 mm or less, dispersion is performed while measuring a circulation flow rate, and the circulation flow rate is changed from the start of dispersion. A method for producing a dispersion, wherein the output of a circulating member such as a pump for feeding a dispersion chamber is increased from a steady state until a predetermined amount is reached.
[0039]
(2) In the method for producing a dispersion liquid, the circulation flow rate is set in a range of 50 to 100% of a steady state until the circulation flow rate reaches a predetermined amount from the start of dispersion. A method for preparing the dispersion described in the above.
[0040]
(3) The titanyl phthalocyanine crystal has a maximum diffraction peak at least at 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray of CuKα (wavelength 1.542 °). The method for producing a dispersion according to the above (1) or (2).
[0041]
(4) The titanyl phthalocyanine crystal further exhibits 9.4 °, 9.6 °, and 24.0 ° diffraction peaks (± 0.2 °) at a Bragg angle of 2θ with respect to CuKα characteristic X-rays (wavelength 1.542 °).゜ has a main peak and the lowest diffraction peak has a peak at 7.3 °, and has no peak in the range of 7.4 ° or more and less than 9.4 °. The method for producing a dispersion according to the above (3).
[0042]
(5) The method of (3) or (4) above, wherein the titanyl phthalocyanine further has no peak at 26.3 °.
[0043]
(6) In the method for producing a dispersion liquid, any one of the above (1) to (5), wherein at least one kind selected from a ketone solvent, an ester solvent, and an ether solvent is used as the dispersion solvent. 3. The method for producing a dispersion according to item 1.
[0044]
(7) The method for producing a dispersion according to any one of (1) to (6), wherein a binder resin is used in combination when dispersing the titanyl phthalocyanine crystal.
[0045]
(8) The method for producing a dispersion according to any one of (1) to (6), wherein water is used in combination when dispersing the titanyl phthalocyanine crystal.
[0046]
(9) In an electrophotographic photoreceptor obtained by laminating at least a charge generation layer and a charge transport layer on a conductive support, the charge generation layer is formed by the method according to any one of the above (1) to (8). An electrophotographic photoreceptor formed using the prepared dispersion.
[0047]
(10) The electrophotographic photoreceptor according to (9), wherein the charge transport layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain.
[0048]
(11) The electrophotographic photosensitive member according to (9) or (10), wherein a protective layer is laminated on the charge transport layer.
[0049]
(12) The protective layer has a specific resistance of 10¹⁰The electrophotographic photoreceptor according to the above (11), comprising an inorganic pigment or a metal oxide of Ω · cm or more.
[0050]
(13) The electrophotographic photoreceptor according to any one of (9) to (12), wherein the charge transport layer is formed using a non-halogen solvent.
[0051]
(14) The electrophotographic photoreceptor according to (13), wherein the non-halogen solvent is at least one selected from cyclic ethers and aromatic hydrocarbons.
[0052]
(15) The electrophotographic photosensitive member according to any one of (9) to (14), wherein the surface of the conductive support is subjected to an anodic oxide film treatment.
[0053]
(16) In an image forming apparatus including at least a charging unit, an exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member, the electrophotographic photosensitive member is described in any one of the above (9) to (15). An image forming apparatus, which is a photosensitive member.
[0054]
(17) In an image forming apparatus in which a plurality of image forming elements including at least a charging unit, an exposing unit, a developing unit, a transferring unit, and an electrophotographic photoreceptor are arranged, the electrophotographic photoreceptor may be any of the above (9) to (15). An image forming apparatus comprising the electrophotographic photosensitive member according to any one of the above.
[0055]
(18) The image forming apparatus according to (16) or (17), wherein a contact charging system is used for the charging unit.
[0056]
(19) The image forming apparatus according to (16) or (17), wherein a non-contact proximity arrangement method is used for the charging unit.
[0057]
(20) The image forming apparatus according to the above (19), wherein a gap between the charging member used for the charging unit and the photoconductor is 10 μm or more and 200 μm or less.
[0058]
(21) The image forming apparatus according to any one of (16) to (20), wherein an AC voltage is superimposed on a DC voltage and applied to the charging unit.
[0059]
(22) A process cartridge for an image forming apparatus including at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of (9) to (15). A process cartridge for an image forming apparatus, comprising:
[0060]
Hereinafter, the present invention will be described in more detail.
First, a method for synthesizing a crude product of titanyl phthalocyanine crystal will be described.
Methods for synthesizing phthalocyanines have been known for a long time, and are described in Moser et al., "Phthalocyanine Compounds" (1963), "The Phthalocyanines" (1983), and JP-A-6-293768.
[0061]
For example, a first method is to heat a phthalic anhydride, a metal or a mixture of a metal halide and urea in the presence or absence of a high-boiling solvent. In this case, a catalyst such as ammonium molybdate is used as needed.
[0062]
A second method is a method in which phthalonitriles and a metal halide are heated in the presence or absence of a high boiling point solvent. This method is used for phthalocyanines that cannot be produced by the first method, for example, aluminum phthalocyanines, indium phthalocyanines, oxovanadium phthalocyanines, oxotitanium phthalocyanines, zirconium phthalocyanines, and the like.
[0063]
As a third method, phthalic anhydride or phthalonitrile is first reacted with ammonia to produce an intermediate such as 1,3-diiminoisoindoline and then in a high-boiling solvent with a metal halide. It is a method of reacting.
[0064]
A fourth method is a method in which a phthalonitrile is reacted with a metal alkoxide in the presence of urea or the like. In particular, the fourth method does not cause chlorination (halogenation) to a benzene ring, and is a very useful method for synthesizing an electrophotographic material.
[0065]
Next, a method for synthesizing amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) will be described.
In this method, a phthalocyanine is dissolved in sulfuric acid, then diluted with water and reprecipitated, and a method called an acid paste method or an acid slurry method can be used.
[0066]
As a specific method, the above-mentioned synthetic crude product is dissolved in 10 to 50 times the volume of concentrated sulfuric acid, and if necessary, insolubles are removed by filtration or the like, and this is sufficiently cooled to 10 to 50 times the volume of sulfuric acid. Slowly put into water or ice water to reprecipitate titanyl phthalocyanine. After filtration of the precipitated titanyl phthalocyanine, washing and filtration are performed with ion-exchanged water, and this operation is sufficiently repeated until the filtrate becomes neutral. Finally, after washing with clean ion-exchanged water, filtration is performed to obtain a water paste having a solid concentration of about 5 to 15 wt%.
[0067]
The product thus prepared is amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used in the present invention.
At this time, the amorphous titanyl phthalocyanine (low-crystalline titanyl phthalocyanine) has a diffraction peak (± 0.2 °) at a Bragg angle 2θ of at least 7.0 to 7 with respect to the characteristic X-ray of CuKα (wavelength 1.514 °). It preferably has a maximum diffraction peak at 0.5 °. In particular, the half width of the diffraction peak is more preferably 1 ° or more. Further, it is important that the major axis of the primary particles be 0.1 μm or less in order to form finer primary particles in the subsequent crystal conversion step.
[0068]
Next, a crystal conversion method will be described.
In the crystal transformation, the amorphous titanyl phthalocyanine (low-crystalline titanyl phthalocyanine) is converted at least as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to a desired crystal form (characteristic X-ray of CuKα (wavelength 1.542 °)). (A crystal form having a maximum diffraction peak at 27.2 °). In particular, among the above crystal forms, they further have major peaks at 9.4 °, 9.6 °, and 24.0 °, and have a peak at 7.3 ° as the diffraction peak on the lowest angle side, A titanyl phthalocyanine crystal having no peak in the range of 7.4 to less than 9.4 ° is preferably used, and a titanyl phthalocyanine crystal having no peak at 26.3 ° is particularly preferably used.
[0069]
As a specific method, the amorphous type titanyl phthalocyanine (low-crystalline titanyl phthalocyanine) is not dried, but is mixed and stirred with an organic solvent in the presence of water to obtain the crystal form.
At this time, as the organic solvent used, any organic solvent can be used as long as a desired crystal form can be obtained. In particular, tetrahydrofuran, toluene, methylene chloride, carbon disulfide, orthodichlorobenzene, 1,1,1 Good results are obtained when one selected from 2-trichloroethane is selected. These organic solvents are preferably used alone, but it is also possible to use a mixture of two or more of these organic solvents or a mixture with another solvent.
[0070]
Subsequently, the crystal-converted titanyl phthalocyanine crystal is immediately filtered to be separated from the crystal conversion solvent. This filtration is performed by using a filter of an appropriate size. At this time, it is most appropriate to use vacuum filtration.
Thereafter, the separated titanyl phthalocyanine crystals are heated and dried as necessary. Any known dryer can be used for the heating and drying. However, when the drying is performed in the atmosphere, a blow dryer is preferable. Further, drying under reduced pressure is also a very effective means for increasing the drying speed and more remarkably exhibiting the effects of the present invention. In particular, it is an effective means for a material that decomposes at a high temperature or changes its crystal form. In particular, it is effective to dry in a state where the degree of vacuum is higher than 10 mmHg.
[0071]
Here, an organic pigment having a high photocarrier generation ability as used in the present invention generally has a very strong cohesive force. When the crystals are filtered and separated and then dried as described above, the primary particles aggregate to form secondary particles. In this method, primary particles can be dispersed by a usual dispersing apparatus. However, if the crystal conversion solvent and the dispersion solvent used subsequently are the same, it is not necessary to intentionally dry. In this case, the wet cake of the titanyl phthalocyanine crystal after the filtration may be directly added to the dispersion solvent in which the binder resin is dissolved, if necessary, to perform dispersion. This method eliminates the need to disperse large agglomerates of secondary particles, making the effects of the present application even more remarkable.
[0072]
The titanyl phthalocyanine crystal thus obtained is extremely useful as a charge generating substance for an electrophotographic photosensitive member. In particular, a crystal type having a maximum diffraction peak at least at 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα has extremely high photocarrier generation efficiency. It has. Among them, diffraction peaks (± 0.2 °) at a Bragg angle of 2θ with respect to characteristic X-rays (wavelength 1.542 °) of CuKα further have major peaks at 9.4 °, 9.6 °, and 24.0 °. And has a peak at 7.3 ° as a diffraction peak on the lowest angle side, does not have a peak in a range of 7.4 ° or more and less than 9.4 °, and more preferably further has a peak at 26.3 °. A titanyl phthalocyanine crystal having no crystal has a very high sensitivity, a small decrease in chargeability upon repeated use, and is a good material.
[0073]
Next, a bead mill dispersing apparatus used for preparing the dispersion of the present invention will be described.
The bead mill dispersing apparatus is generally used for the production of paints and the like, and an example thereof is shown in FIG.
In FIG. 1, 1 is a motor, 2 is a dispersion chamber, 3 is a flow meter, 4 is a circulation tank, 5 is a circulation pump, 6 is a pipe, and 7 is a base for fixing the dispersion chamber. Although not shown, providing a cooling jacket around the dispersion chamber 2 and the circulation tank 4 in FIG. 1 is very effective in the present invention. The flow meter 3 may be installed at any place in the circulation pipe, but is desirably installed near the circulation outlet so as to detect clogging at an early stage.
[0074]
FIG. 2 illustrates the inside of the dispersion chamber 2 in FIG. Here, 10 is a dispersion medium, 11 is a slit for preventing the dispersion medium from flowing out, 12 is a pipe on the circulation outlet side, 13 is a wall of the dispersion chamber, 14 is a rotor, 15 is a pipe on the circulation inlet side, and 16 is a pipe on the circulation inlet side. The shaft connected to the motor.
The capacity of the dispersion chamber is a part of the volume of the dispersion chamber wall excluding the pipe portion shown in FIG. 2 excluding the volume occupied by the shaft 16 and the rotor 14.
[0075]
The larger the rotor diameter shown in FIG. 2, the stronger the dispersion energy can be generated. Further, the dispersion energy can be changed by the number of rotations. However, as described above, the titanyl phthalocyanine crystal used in the present invention is a material that easily undergoes crystal transition, but if the rotor diameter is too large, it is necessary to reduce the number of rotations, There is a limit to the torque of the motor, and if the rotor diameter is increased more than necessary, uneven rotation will occur, and the operation of the disperser itself will become unstable. For this reason, an appropriate rotor diameter is 100 mm or less (preferably 50 mm or less), and 10 mm or more is appropriate.
Examples of the material constituting the rotor include various metals (for example, stainless steel) and various ceramics (for example, alumina and zirconia). Considering the abrasion resistance of repeated use and contamination contamination in the dispersion. , Zirconia or partially stabilized zirconia in which a part of the composition is modified with yttrium or the like is preferably used.
[0076]
As for the dispersion media, the outer diameter is desirably 1.0 mm or less, more preferably 0.5 mm or less. On the other hand, if it is too small, the specific surface area becomes large and problems such as easy polishing occur. Therefore, the thickness is preferably 0.1 mm or more. As a material constituting the dispersion medium, the same material as that of the rotor can be mentioned, and also in the dispersion medium, zirconia or partially stabilized zirconia having a part of the composition modified with yttrium or the like is preferably used.
[0077]
There is no particular limitation on the number of revolutions of the rotor, but if the number of revolutions is high, the amount of dispersion energy naturally increases, so that excess energy is given to the titanyl phthalocyanine crystal. Therefore, in the case of a rotor having a diameter of 50 mm, about 3000 rotations (rpm) or less is appropriate.
[0078]
The dispersion time is necessarily selected from the dispersion state of the pigment. If the dispersion time is too short, the particles may be pulverized, but the dispersion stability may be poor. The minimum time during which dispersion-reagglomeration equilibrium can be created should be ensured.
[0079]
Next, a method for producing a dispersion in the present invention will be described.
The pigment used is a titanyl phthalocyanine crystal as described above, and preferably has a diffraction peak (± 0.2 °) at a Bragg angle 2θ of at least 27.2 ° with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα. It is a titanyl phthalocyanine crystal having a crystal form having a maximum diffraction peak.
More preferably, it has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα, and further has a peak of 9.4 ° and 9 °. It has a main peak at 6.6 ° and 24.0 °, has a peak at 7.3 ° as the diffraction peak on the lowest angle side, and has a peak in the range of 7.4 ° or more and less than 9.4 °. It is a titanyl phthalocyanine crystal without. In addition, a titanyl phthalocyanine crystal having no peak at 26.3 ° is most suitable.
These titanyl phthalocyanine crystals are put into the above-mentioned bead mill dispersing device together with an organic solvent and dispersed to prepare a dispersion.
[0080]
The amount of dispersion solvent used, which determines the scale of the entire dispersion. The ratio can be set arbitrarily by increasing the size of the circulation tank. According to the study of the present inventor, according to the weight of the titanyl phthalocyanine crystal, the amount of dispersion energy (in other words, the product of the dispersion force per unit time determined by the rotation speed of the rotor, the diameter of the dispersion medium, and the like, and the dispersion time) ) Were in a proportional relationship, it was found that the dispersion state (attained particle size, dispersion stability, etc.) was almost the same. Therefore, the weight of the titanyl phthalocyanine crystal used and the dispersion time basically have a proportional relationship. Therefore, when the scale is increased, the dispersion time may be increased accordingly.
However, there arises a problem that the dispersion time becomes too long and the size of the apparatus becomes larger. Further, it is preferable to provide a stirring device in the circulation tank. When the capacity of the circulation tank is increased, the stirring capacity must be increased accordingly, and the energy (electric power, etc.) used must be increased. Would.
From the above, the ratio of the used amount (volume) of the dispersion solvent to the volume of the dispersion chamber is appropriately in the range of about 5: 1 to 50: 1. More preferably, it is in the range of 10: 1 to 50: 1.
[0081]
As a dispersing solvent to be used, any organic solvent that is usually used can be used as long as it can disperse the titanyl phthalocyanine crystal. Examples include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. Among them, good results can be obtained by using one selected from ketone solvents, ester solvents, and ether solvents. These organic solvents may be used alone or as a mixture.
[0082]
At the time of dispersion, a binder resin is used in combination as necessary. The combined use of a binder resin is a very effective means since the rate of crystal transition of the titanyl phthalocyanine crystal is significantly reduced.
Examples of binder resins that can be used include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinyl carbazole, polyacrylamide, and polyvinyl benzal. , Polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like. In particular, polyvinyl butyral can be used most effectively.
The amount of the binder resin is suitably from 0 to 500 parts by weight, preferably from 10 to 300 parts by weight, per 100 parts by weight of the titanyl phthalocyanine crystal.
[0083]
In addition, water is used in combination for dispersion as needed. The combined use of water is a very effective means since the rate of crystal transition of the titanyl phthalocyanine crystal is remarkably reduced as in the case of the binder resin. When used, distilled water or ion-exchanged water from which impurities have been sufficiently removed is preferably used. If used in an excessively large amount, problems such as a decrease in dispersibility, separation from an organic solvent, and precipitation of a binder resin occur. Therefore, depending on the type of the organic solvent used, the upper limit of the solubility of water in the organic solvent in the case of a hydrophobic solvent, and 2 to 3 wt% based on the weight of the organic solvent in the case of a hydrophilic solvent. The degree is the upper limit.
[0084]
As a dispersion procedure, an appropriate amount of an organic solvent, titanyl phthalocyanine crystal, a binder resin and water as needed are charged into a circulation tank 4 of a bead mill dispersion apparatus as shown in FIG. 1, and sufficiently stirred. When a binder resin or water is used in combination, it is desirable to previously mix and dissolve it with an organic solvent in another device. By the stirring in the circulation tank 4, the titanyl phthalocyanine crystals are sufficiently mixed in the vehicle. When the mixture is sufficiently mixed, the circulation pump 5 is operated to supply the dispersion from the circulation tank to the dispersion chamber. At this time, before the organic solvent and the titanyl phthalocyanine crystal are mixed, the organic solvent is sent to the dispersion chamber 2 in advance, and filling the dispersion chamber is effective in preventing clogging at the outlet of the dispersion chamber. It is a large and effective tool. Rotating the rotor of the dispersion chamber before sending the dispersion liquid is also an effective means for preventing clogging at the outlet of the dispersion chamber.
[0085]
Next, the titanyl phthalocyanine crystal contained in the dispersion liquid supplied to the dispersion chamber 2 is dispersed. In the initial state of the dispersion, there is a time during which a predetermined flow rate cannot be obtained with respect to a liquid sent by a pump or the like. Therefore, in the present specification, the “initial state of dispersion” means a state from the start of dispersion to the time when the amount of circulating liquid reaches a predetermined amount. If the dispersion is performed in a state where the flow rate is reduced during this time period, excessive dispersion energy is given to the titanyl phthalocyanine crystal, and crystal transition occurs. The previous time is considered to be until all of the titanyl phthalocyanine crystals subjected to dispersion pass through the dispersion chamber once, but since the flow rate change depending on clogging may differ from dispersion to dispersion, The flow rate is measured at any time, and the output of the liquid feeding member (liquid feeding pump, liquid feeding stirrer, etc.) is increased until the flow rate of 90% or more of the predetermined flow rate flows, and the flow rate is not reduced. It is important to do the dispersion.
[0086]
In this way, after the dispersion initial state, the flow rate according to the output of the liquid sending member is secured, and the flow rate tends to exceed the predetermined flow rate. In such a state, the flow rate becomes substantially constant with respect to the output of the liquid sending member (steady state), so that the output is reduced to a predetermined output and the dispersion is continued. The steady state of dispersion refers to a state in which the flow rate obtained by sending liquid from a pump or the like maintains a range of about ± 10% of a predetermined amount, and indicates a state in which continuous operation of circulation dispersion is enabled. is there.
[0087]
Dispersion is terminated under predetermined conditions and controlled by the dispersion time, but it is desirable to perform the dispersion while checking the state of the dispersion. For example, there is a method of measuring a particle diameter or forming a thin film and observing a coating film state with a microscope. In the former case, it may not be possible to measure a small amount of coarse particles, and when it is used as a dispersion for forming a thin film such as a charge generating layer of a photoreceptor, it is not an optimal method, but a simple method such as the latter. It is desirable to confirm with a sample equivalent to the actual use condition.
[0088]
When such a predetermined dispersion time is completed, the dispensing of the dispersion is performed. Generally, although there is an upper limit due to various restrictions, the higher the pigment concentration, the higher the dispersion efficiency. This is explained by the increased probability of contact with the distributed media. Generally, the dispersion is performed within a range of about 5 to 15% as the pigment concentration. At such a high pigment concentration, considerable losses occur during the removal of the dispersion. This problem is remarkable especially when the circulation system is long. Normally, the concentration of the dispersion and the concentration of the dispersion used are different, and the former has a higher concentration. Therefore, at least a dilution step exists before use. In the circulating dispersion, performing the dilution together with the dispensing can increase the dispensing efficiency (recovery efficiency), and at the same time, the dispersing device can be washed, which is very efficient. Briefly, after the dispersion is completed, the dispersion liquid (stock solution) is dispensed by a liquid sending pump or the like, and the dispensing by the pump is stopped, or a solvent for dilution is put into the circulation tank immediately before the dispensing, and then dispensed by the pump again. . At this time, it is important not to circulate as much as possible. By dispensing before returning to the circulation tank, the circulation system becomes clean and the dispensing efficiency increases.
As described above, a dispersion containing titanyl phthalocyanine crystals is produced.
[0089]
Next, the electrophotographic photosensitive member of the present invention will be described with reference to the drawings.
FIG. 3 is a cross-sectional view illustrating an electrophotographic photoreceptor of the present invention. A charge generation layer 35 mainly composed of a charge generation substance and a charge transport layer mainly composed of a charge transport substance are provided on a conductive support 31. 37 are provided.
FIG. 4 is a cross-sectional view showing another configuration example of the electrophotographic photoreceptor of the present invention, and has a configuration in which a protective layer 39 is laminated on a charge generation layer 35 and a charge transport layer 37.
[0090]
The conductive support 31 has a volume resistance of 10¹⁰What shows conductivity of Ωcm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver, metals such as platinum, tin oxide, metal oxides such as indium oxide, by evaporation or sputtering, by film Or cylindrical plastic or paper-coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. plates and extruded, drawn, etc., made into a tube, then cut, super finished, polished etc. Surface-treated tubes and the like can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support 31.
[0091]
Among these, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. Here, aluminum includes both pure aluminum and aluminum alloy. Specifically, JIS A1000 series, 3000 series, 6000 series aluminum or aluminum alloy is most suitable. The anodized film is obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called alumite obtained by anodizing aluminum or an aluminum alloy in an electrolyte solution is a photoreceptor used in the present invention. Is most suitable for In particular, they are excellent in preventing point defects (black spots, background stains) generated when used in reversal development (negative / positive development).
[0092]
The anodic oxidation treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, and sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C, current density: 1-4 A / dm²The treatment is performed within a range of about 5 to 30 minutes and an electrolysis voltage of 5 to 30 V, but is not limited thereto. Since the anodic oxide film thus produced is porous and has high insulating properties, the surface is very unstable. For this reason, there is a temporal change after the production, and the physical property value of the anodic oxide film is likely to change. In order to avoid this, it is desirable to further seal the anodic oxide film.
[0093]
Examples of the sealing treatment include a method of immersing the anodic oxide film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodic oxide film in boiling water, and a method of performing treatment with pressurized steam. Among them, the method of immersing in an aqueous solution containing nickel acetate is most preferable. Subsequent to the sealing treatment, a cleaning treatment of the anodic oxide film is performed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains on the surface of the support (anodic oxide film) excessively, it not only adversely affects the quality of the coating film formed thereon, but also generally causes low resistance components to remain. It will also be the cause. The washing may be carried out once with pure water, but usually at another stage. At this time, it is preferable that the final cleaning liquid is as clean (deionized) as possible. In addition, it is desirable to perform physical rubbing cleaning with a contact member in one of the other cleaning steps.
[0094]
The thickness of the anodic oxide film formed as described above is desirably about 5 to 15 μm. If the thickness is too thin, the barrier properties of the anodic oxide film will not be sufficient.If the thickness is too thick, the time constant of the electrode will be too large, resulting in the generation of residual potential and reduced photoconductor response. May be.
[0095]
In addition, a material obtained by dispersing a conductive powder in a suitable binder resin on the above support and applying the same 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, and metal oxide powder such as conductive tin oxide and ITO. Can be The binder resins used simultaneously include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and 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 or photo-curable resins such as melamine resin, urethane resin, phenol resin and alkyd resin. Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the dispersion.
[0096]
Furthermore, a conductive material is formed by a heat-shrinkable tube made of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or Teflon (R) on a suitable cylindrical substrate. Those provided with a layer can also be favorably used as the conductive support 31 of the present invention.
[0097]
Next, the photosensitive layer will be described.
The charge generation layer 35 is a layer formed using the above-described dispersion mainly containing titanyl phthalocyanine crystal. Preferably, a crystalline titanyl phthalocyanine crystal having a maximum diffraction peak at least at 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα is used. . In particular, among the above crystal forms, they further have major peaks at 9.4 °, 9.6 °, and 24.0 °, and have a peak at 7.3 ° as the diffraction peak on the lowest angle side, A titanyl phthalocyanine crystal having no peak in the range of 7.4 ° or more and less than 9.4 ° is preferably used, and a titanyl phthalocyanine crystal having no peak at 26.3 ° is particularly preferably used. As a method for applying the dispersion, a method such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, and ring coating can be used. The thickness of the charge generation layer 35 is appropriately about 0.01 to 5 μm, and preferably 0.1 to 2 μm.
[0098]
The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, applying the solution on the charge generation layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.
The charge transport materials include a hole transport material and an electron transport material.
[0099]
Examples of the charge transport material include chloranil, bromanil, 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-trione Electron accepting substances such as nitrodibenzothiophene-5,5-dioxide, benzoquinone derivatives and the like.
[0100]
Examples of the hole transport material include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethylglutamate and derivatives thereof, pyrene-formaldehyde condensate and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, and oxazole derivatives. Oxadiazole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative, α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9-styrylanthracene derivative, pyrazoline Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. And other known materials. These charge transport materials are used alone or in combination of two or more.
[0101]
Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, and poly (vinyl acetate). Vinylidene chloride, polyalate, 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, melamine resin, urethane resin, phenol resin And a thermoplastic or thermosetting resin such as an alkyd resin.
[0102]
The amount of the charge transporting material is suitably 20 to 300 parts by weight, preferably 40 to 150 parts by weight based on 100 parts by weight of the binder resin. Further, the thickness of the charge transport layer is preferably about 5 to 100 μm. As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among them, cyclic ethers such as tetrahydrofuran and dioxane, which are non-halogen solvents, and aromatic hydrocarbons such as toluene and xylene are preferably used.
Using these non-halogen solvents as a coating solvent for the charge transport layer and using titanyl phthalocyanine crystals as the charge generating substance, there are cases where desired light sensitivity cannot be obtained, but using the dispersion in the present invention. When formed, such a thing does not occur. It is presumed that the reason for this is that fine particles are being formed and crystal transition is small.
[0103]
For the charge transport layer, a polymer charge transport material having both a function as a charge transport material and a function as a binder resin is preferably used. The charge transport layer composed of these polymeric charge transport materials has excellent abrasion resistance. As the polymer charge transporting substance, known materials can be used, and particularly, a polycarbonate containing a triarylamine structure in a main chain and / or a side chain is preferably used. Among them, polymer charge transport materials represented by the following formulas (1) to (10) are preferably used. These are exemplified below and specific examples are shown below.
[0104]
Embedded image

Where R₁, R₂, R₃Are each independently a substituted or unsubstituted alkyl group or halogen atom, R₄Is a hydrogen atom or a substituted or unsubstituted alkyl group, R₅, R₆Is a substituted or unsubstituted aryl group, o, p, and q are each independently an integer of 0 to 4, k and j each represent a composition, and 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 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.
[0105]
Embedded image

R₁₀₁, R₁₀₂Each independently represents a substituted 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 or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -SO₂—, —CO—, —CO—O—Z—O—CO— (wherein Z represents an aliphatic divalent group) or
Embedded image

(A is an integer of 1 to 20, b is an integer of 1 to 2000, R₁₀₃, R₁₀₄Represents a substituted or unsubstituted alkyl group or an aryl group). Where R₁₀₁And R₁₀₂, R₁₀₃And R₁₀₄May be the same or different.
[0106]
Embedded image

Where R₇, R₈Is a substituted or unsubstituted aryl group, Ar₁, Ar₂, Ar₃Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0107]
Embedded image

Where R₉, R₁₀Is a substituted or unsubstituted aryl group, Ar₄, Ar₅, Ar₆Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0108]
Embedded image

Where R₁₁, R₁₂Is a substituted or unsubstituted aryl group, Ar₇, Ar₈, Ar₉Represents the same or different arylene group, and p represents an integer of 1 to 5. X, k, j and n are the same as in the case of the expression (1).
[0109]
Embedded image

Where R_Thirteen, R₁₄Is a substituted or unsubstituted aryl group, Ar₁₀, Ar₁₁, Ar₁₂Are the same or different arylene groups, X₁, X₂Represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j and n are the same as in the case of the expression (1).
[0110]
Embedded image

Where R_Fifteen, R₁₆, R₁₇, R₁₈Is a substituted or unsubstituted aryl group, Ar_Thirteen, Ar₁₄, Ar_Fifteen, Ar₁₆Are the same or different arylene groups, Y₁, Y₂, Y₃Represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group, and may be the same or different. X, k, j and n are the same as in the case of the expression (1).
[0111]
Embedded image

Where R₁₉, R₂₀Represents a hydrogen atom, a substituted or unsubstituted aryl group;₁₉And R₂₀May form a ring. Ar₁₇, Ar₁₈, Ar₁₉Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0112]
Embedded image

Where R₂₁Is a substituted or unsubstituted aryl group, Ar₂₀, Ar₂₁, Ar₂₂, Ar₂₃Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0113]
Embedded image

Where R₂₂, R₂₃, R₂₄, R₂₅Is a substituted or unsubstituted aryl group, Ar₂₄, Ar₂₅, Ar₂₆, Ar₂₇, Ar₂₈Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0114]
Embedded image

Where R₂₆, R₂₇Is a substituted or unsubstituted aryl group, Ar₂₉, Ar_{3 0}, Ar₃₁Represents the same or different arylene groups. X, k, j and n are the same as in the case of the expression (1).
[0115]
In addition, as the polymer charge transporting material used in the charge transporting layer, in addition to the above-described polymer charge transporting material, in the state of a monomer or oligomer having an electron donating group when forming the charge transporting layer, A polymer having a two-dimensional or three-dimensional crosslinked structure is finally included by a curing reaction or a crosslinking reaction.
[0116]
A charge transport layer composed of a polymer having an electron donating group or a polymer having a crosslinked structure has excellent abrasion resistance. Normally, in an electrophotographic process, the charging potential (potential of an unexposed portion) is constant. Therefore, when the surface layer of the photoconductor is worn by repeated use, the electric field intensity applied to the photoconductor increases accordingly. As the electric field intensity increases, the frequency of occurrence of background contamination increases. Therefore, the high wear resistance of the photoconductor is advantageous against background contamination. The charge transport layer composed of a polymer having an electron donating group is excellent in film-forming properties because it is a polymer compound itself, and has a charge transport site as compared with the charge transport layer composed of a low molecular weight dispersed polymer. It can be formed at high density and has excellent charge transporting ability. Therefore, a high-speed response can be expected for a photoreceptor having a charge transport layer using a polymer charge transport material.
[0117]
Other polymers having an electron donating group include copolymers of known monomers, block polymers, graft polymers, star polymers, and, for example, JP-A-3-109406, JP-A-2000- It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-206723, JP-A-2001-34001 and the like. Also in this case, a material that can satisfy the above mobility can be effectively used.
[0118]
In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37.
As the plasticizer, those used as general plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is suitably about 0 to 30% by weight based on the binder resin.
As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used. 1% by weight is suitable.
[0119]
As the binder resin, in addition to using the binder resin described above for the charge transport layer 37 as it is, a mixture of the binder resins described in the method for preparing the dispersion may be used. Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight based on 100 parts by weight of the binder resin, and the amount of the charge transporting substance is preferably 1 to 190 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the binder resin. It is.
[0120]
The single-layer photosensitive layer is formed by dip coating or spraying a coating liquid obtained by dispersing a charge generating substance and a binder resin together with a charge transporting substance, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane using a dispersing machine or the like. It can be formed by coating with a coat or a bead coat. The thickness of the single-layer photosensitive layer is suitably about 5 to 100 μm.
[0121]
In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins may be resins having high solvent resistance to general organic solvents. desirable.
Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, copolymer-soluble nylons, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resins, phenol resins, alkyd-melamine resins, and epoxy resins. Curable resins that form a three-dimensional network structure, such as resins, are exemplified. Further, a fine powder pigment of a metal oxide 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 moiré and reduce residual potential.
[0122]
These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-described photosensitive layer. Further, 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 Al₂O₃Provided by anodic oxidation, organic substances such as polyparaxylylene (parylene) or SiO₂, SnO₂, TiO₂, ITO, CeO₂Also, inorganic materials such as those provided by a vacuum thin film forming method can be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0123]
In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. 2. Description of the Related Art In recent years, computers have been used on a daily basis, and there is a demand for high-speed output by a printer and downsizing of the apparatus. Therefore, by providing a protective layer and improving the durability, the photosensitive member of the present invention having high sensitivity and having no abnormal defects can be used effectively.
[0124]
Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyarylate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenthene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polychloride Resins such as vinyl, polyvinylidene chloride, and epoxy resin are exemplified. Among them, polycarbonate or polyarylate can be most preferably used.
[0125]
In addition to the protective layer, a fluorine resin such as polytetrafluoroethylene, a silicone resin, and an inorganic filler such as titanium oxide, tin oxide, potassium titanate, silica, etc. A filler or the like dispersed therein can be added.
[0126]
Further, among the filler materials used for the protective layer of the photoreceptor, examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like. Are metal powders such as copper, tin, aluminum and indium; metals such as silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, and tin-doped indium oxide. Inorganic materials such as oxides and potassium titanate are exemplified. Particularly, from the viewpoint of the hardness of the filler, it is advantageous to use an inorganic material among them. In particular, silica, titanium oxide, and alumina can be effectively used.
The filler concentration in the protective layer varies depending on the type of filler used and the electrophotographic process conditions using the photoreceptor, but is 5% by weight or more, preferably 5% by weight or more, based on the total solids on the outermost layer side of the protective layer. 10% by weight or more and 50% by weight or less, more preferably about 30% by weight or less is good.
[0127]
The volume average particle diameter of the filler to be used is preferably 0.1 μm to 2 μm, and more preferably 0.3 μm to 1 μm. In this case, if the average particle size is too small, the abrasion resistance is not sufficiently exhibited, and if the average particle size is too large, the surface properties of the coating film deteriorate, or the coating film itself cannot be formed.
The average particle size of the filler in the present invention is a volume average particle size unless otherwise specified, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). In this case, the particle diameter was calculated as a particle diameter (Median type) corresponding to 50% of the cumulative distribution. It is important that the standard deviation of each particle measured at the same time is 1 μm or less. If the value of the standard deviation is larger than this, the effect of the present invention may not be obtained remarkably because the particle size distribution is too wide.
[0128]
Further, the pH of the filler used in the present invention greatly affects the resolution and the dispersibility of the filler.
As one of the reasons, it is considered that hydrochloric acid or the like remains during the production of fillers, especially metal oxides. When the residual amount is large, the occurrence of image blur is inevitable, and depending on the residual amount, it may affect the dispersibility of the filler.
[0129]
Another reason is that the chargeability on the surface of the filler, especially the metal oxide, is different. Normally, particles dispersed in a liquid are positively or negatively charged, and ions having the opposite charge gather in an attempt to keep it electrically neutral, where an electric double layer is formed. Stabilizes the dispersed state of particles. As the distance from the particle increases, its potential (zeta potential) gradually decreases, and the potential of a region sufficiently far from the particle and electrically neutral becomes zero. Therefore, the stability increases due to an increase in the absolute value of the zeta potential due to an increase in the repulsive force of the particles, and the particles tend to aggregate and become unstable as they approach zero. On the other hand, the zeta potential varies greatly depending on the pH value of the system, and at a certain pH value, the potential becomes zero and has an isoelectric point. Therefore, the dispersion system is stabilized by increasing the absolute value of the zeta potential as far as possible from the isoelectric point of the system.
[0130]
In the constitution of the present invention, as the filler, those having a pH at the above-mentioned isoelectric point of at least 5 are preferable from the viewpoint of suppressing image blur, and the more the filler is more basic, the higher the effect tends to be. It was confirmed that there was. The filler having a high pH at the isoelectric point and exhibiting a basic property has a higher zeta potential when the system is acidic, so that the dispersibility and the stability thereof are improved.
Here, the pH of the filler in the present invention is a pH value at the isoelectric point from the zeta potential. At this time, the zeta potential was measured with a laser zeta potentiometer manufactured by Otsuka Electronics Co., Ltd.
[0131]
Further, as a filler which is less likely to cause image blur, a filler having a high electrical insulation property (a specific resistance of 10¹⁰Ω · cm or more), and those having a filler pH of 5 or more and those having a filler dielectric constant of 5 or more can be used particularly effectively. In addition, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more may be used alone, or a mixture of two or more fillers having a pH of 5 or less and a filler having a pH of 5 or more may be used. It is also possible to use a mixture of two or more fillers having a dielectric constant of 5 or less and a filler having a dielectric constant of 5 or more. Among these fillers, α-alumina, which has high insulation properties, high thermal stability, and high abrasion resistance, has a hexagonal close-packed structure, is used to suppress image blur and improve abrasion resistance. Especially useful.
[0132]
The specific resistance of the filler used in the present invention is defined as follows. Since the specific resistance of a powder such as a filler varies depending on the filling rate, it is necessary to measure the powder under a certain condition. In the present invention, the specific resistance value of the filler was measured using an apparatus having the same configuration as the measuring apparatus shown in FIG. 1 of JP-A-5-94049 and FIG. 1 of JP-A-5-113688. This value was used. In the measuring device, the electrode area is 4.0 cm²It is. Before the measurement, a load of 4 kg is applied to one electrode on one side for 1 minute, and the amount of the sample is adjusted so that the distance between the electrodes becomes 4 mm. At the time of the measurement, the measurement is performed under a load state of the weight (1 kg) of the upper electrode, and the applied voltage is measured at 100V. 10⁶The region of Ω · cm or more was measured with a HIGH RESISTANCE METER (Yokogawa Hewlett-Packard), and the region below Ω · cm was measured with a digital multimeter (Fluque). The specific resistance value thus obtained is defined as the specific resistance value according to the present invention.
[0133]
The dielectric constant of the filler was measured as follows. After applying a load using the same cell as that for measuring the specific resistance as described above, the capacitance was measured, and the dielectric constant was determined from this. The capacitance was measured using a dielectric loss measuring device (manufactured by Ando Electric).
[0134]
Furthermore, these fillers can be surface-treated with at least one surface treatment agent, and it is preferable to do so from the viewpoint of filler dispersibility. A decrease in the dispersibility of the filler not only increases the residual potential, but also causes a decrease in the transparency of the coating film, the occurrence of coating film defects, and a decrease in abrasion resistance, which hinders high durability or high image quality. It can evolve into a big problem.
[0135]
As the surface treatment agent, all the surface treatment agents conventionally used can be used, but a surface treatment agent capable of maintaining the insulating property of the filler is preferable. For example, titanate-based coupling agents, aluminum-based coupling agents, zirco-aluminate-based coupling agents, higher fatty acids, etc., or a mixture treatment of these with a silane coupling agent, Al₂O₃, TiO₂, ZrO₂, Silicone, aluminum stearate, etc., or a mixture thereof is more preferable from the viewpoint of filler dispersibility and image blur.
The treatment with the silane coupling agent has a strong effect of image blur, but the effect of mixing the surface treatment agent with the silane coupling agent may be suppressed in some cases.
[0136]
The surface treatment amount varies depending on the average primary particle size of the filler used, but 3 to 30% by weight is suitable, and 5 to 20% by weight is more preferable. If the amount of the surface treatment is smaller than this, the effect of dispersing the filler cannot be obtained, and if the amount is too large, the residual potential is significantly increased.
[0137]
These filler materials are used alone or in combination of two or more. The surface treatment amount of the filler is defined by the weight ratio of the surface treatment agent used to the filler amount as described above.
These filler materials can be dispersed by using an appropriate disperser. Further, from the viewpoint of the transmittance of the protective layer, it is preferable that the filler used is dispersed to the level of the primary particles and the amount of the aggregate is small.
[0138]
Further, the protective layer may contain a charge transporting substance for reducing the residual potential and improving the response. As the charge transporting substance, the materials described in the description of the charge transporting layer can be used. When a low molecular charge transport material is used as the charge transport material, a concentration gradient in the protective layer may be provided. It is an effective means to reduce the concentration on the surface side in order to improve abrasion resistance.
[0139]
The concentration here represents the ratio of the weight of the low-molecular charge transporting substance to the total weight of all the materials constituting the protective layer, and the concentration gradient is such that the concentration becomes lower on the surface side at the above weight ratio. It indicates that.
The use of a charge transport polymer is very advantageous in that the durability of the photoreceptor is improved.
[0140]
As a method for forming the protective layer, a normal coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm. In addition to the above, known materials such as aC and a-SiC formed by a vacuum thin film forming method can be used as the protective layer.
[0141]
As described above, the use of a polymeric charge transport material in the photosensitive layer (charge transport layer) or the provision of a protective layer on the surface of the photoconductor increases the durability (wear resistance) of each photoconductor. In addition, when used in a tandem-type full-color image forming apparatus as described below, it produces a new effect not found in a monochrome image forming apparatus.
[0142]
In the case of a full-color image, various types of images are input. On the contrary, a standard image may be input. For example, the presence of a seal in a Japanese document or the like. Something like a stamp is usually located near the edge of the image area, and the colors used are also limited. In a state where a random image is always written, image writing, development and transfer are performed on the photoreceptor in the image forming element on average. When a large number of image formations are repeated or when only a specific image formation element is used, the durability of the image formation element is not balanced.
When a photoreceptor having a small surface durability (physical, chemical, mechanical) is used in such a state, the difference becomes remarkable, which tends to cause an image problem. On the other hand, when the photoreceptor is made highly durable, such a local change amount is small, and as a result, it becomes difficult to appear as a defect on an image. It is also very effective.
[0143]
In the electrophotographic photoreceptor of the present invention, an intermediate layer may be provided between the photosensitive layer and the protective layer. The intermediate layer generally uses a binder resin 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 normal coating method is employed as described above. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.
[0144]
Next, the image forming process and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 5 is a schematic diagram for explaining the image forming process or the image forming apparatus of the present invention, and the following modified examples also belong to the category of the present invention.
In FIG. 5, a photoreceptor 1 is provided with a charge generation layer containing a titanyl phthalocyanine crystal dispersed under specific dispersion conditions and a charge transport layer on a conductive support. As the charging member 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid charger (solid state charger), and a charging roller are used. Can be
[0145]
As the charging member, one that is in contact with or close to the photoconductor 1 is preferably used. In addition, when charging the photosensitive member by the charging member, the charging member is charged by an electric field in which an AC component is superimposed on a DC component, thereby effectively reducing charging unevenness.
Here, the contact-type charging member is of a type in which the surface of the charging member comes into contact with the surface of the photoreceptor, and includes a charging roller, a charging blade, and a charging brush. Among them, a charging roller and a charging brush are preferably used.
[0146]
The close-positioned charging member is of a type in which the charging member is closely disposed in a non-contact state so as to have a gap (gap) of 10 to 200 μm or less between the photosensitive member surface and the charging member surface. It is distinguished from known chargers typified by corotrons and scorotrons based on the distance of the gap.
The nearby charging member used in the present invention may have any shape as long as it has a mechanism capable of appropriately controlling the gap with the photoconductor surface. For example, the rotation axis of the photoreceptor and the rotation axis of the charging member may be mechanically fixed so as to have an appropriate gap. Among them, using a charging member in the form of a charging roller, disposing a gap forming member at both ends of the non-image forming portion of the charging member, bringing only this portion into contact with the photoconductor surface, and disposing the image forming region in a non-contact manner, Alternatively, a method in which a gap forming member at both ends of the photoreceptor non-image forming portion is disposed, and only this portion is brought into contact with the surface of the charging member, and the image forming region is disposed in a non-contact manner, stably stabilizes the gap by a simple method. It is a method that can be maintained. In particular, the methods described in JP-A-2002-148904 and JP-A-2002-148905 can be used favorably. FIG. 6 shows an example of a proximity charging mechanism in which a gap forming member is arranged on the charging member side.
[0147]
As the transfer means, the above-mentioned charger can be generally used. However, as shown in FIG. 5, a combination of the transfer charger 10 and the separation charger 11 is effective.
[0148]
Further, an LD or LED is used as a light source of the image exposure unit 5. As a light source such as the static elimination lamp 2, a general light emitting material 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. . To irradiate only light in a desired wavelength range, various 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.
[0149]
The light source irradiates the photoreceptor with light by providing a transfer step, a charge removal step, a cleaning step, or a pre-exposure step using light irradiation in addition to the step shown in FIG.
[0150]
The toner developed on the photoconductor 1 by the developing unit 6 is transferred to the transfer paper 9, but not all of the toner is transferred, and some toner remains on the photoconductor 1. Such toner is removed from the photoconductor by the fur brush 14 and the blade 15.
Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.
[0151]
When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with a negative (positive) polarity toner (electric detection fine particles), a positive image can be obtained, and if it is developed with a positive (negative) polarity toner, a negative image can be obtained.
A known method is applied to the developing unit, and a known method is also used for the charge removing unit.
[0152]
FIG. 7 shows another example of the image forming process according to the present invention. The photoreceptor 21 is provided with a charge generation layer containing a titanyl phthalocyanine crystal dispersed under specific dispersion conditions and a charge transport layer on a conductive support. It is driven by the drive rollers 22a and 22b, and is charged by the charger 23, image exposure by the light source 24, development (not shown), transfer using the charger 25, pre-cleaning exposure by the light source 26, cleaning by the brush 27, cleaning by the light source 28 Static elimination is performed repeatedly. In FIG. 7, the photosensitive member 21 (of course, the support is translucent) is irradiated with light for image exposure from the support side. As the image exposure source 24, an LD or an LED is preferably used.
[0153]
The illustrated image forming process is an example of an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 5, the pre-cleaning exposure is performed from the photosensitive layer side, but this may be performed from the translucent support side, or the irradiation of static elimination light may be performed from the support side.
On the other hand, in the light irradiation step, image exposure, pre-cleaning exposure, and charge removal exposure are shown, but in addition, pre-transfer exposure, pre-exposure of image exposure, and other known light irradiation steps are provided, and the photoconductor is irradiated Irradiation can also be performed.
[0154]
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, or may be incorporated in the apparatus in the form of a process cartridge. The process cartridge is one device (part) including a photoconductor, and further including at least one of a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit. Although there are many shapes and the like of the process cartridge, a general example is shown in FIG. Photoconductor 1 is provided with a charge generation layer containing a titanyl phthalocyanine crystal dispersed under specific dispersion conditions and a charge transport layer on a conductive support.
[0155]
FIG. 9 is a schematic diagram for explaining a tandem-type full-color image forming apparatus of the present invention, and the following modified examples also belong to the category of the present invention.
In FIG. 9, reference numerals 1C, 1M, 1Y, and 1K denote drum-shaped photoconductors. The photoconductors 1C, 1M, 1Y, and 1K rotate in the direction of the arrow in FIG. , 2M, 2Y, 2K, developing members 4C, 4M, 4Y, 4K, and cleaning members 5C, 5M, 5Y, 5K.
[0156]
The charging members 2C, 2M, 2Y, and 2K are charging members constituting a charging device for uniformly charging the surface of the photoconductor. Laser light 3C, 3M, 3Y, 3K from an exposure member (not shown) is irradiated from the back side of the photosensitive member between the charging members 2C, 2M, 2Y, 2K and the developing members 4C, 4M, 4Y, 4K, An electrostatic latent image is formed on each of 1C, 1M, 1Y, and 1K. Then, four image forming elements 6C, 6M, 6Y, and 6K centering on such photoconductors 1C, 1M, 1Y, and 1K are arranged side by side along a transfer conveyance belt 10 that is a transfer material conveyance unit.
[0157]
The transfer conveyance belt 10 contacts the photoconductors 1C, 1M, 1Y, and 1K between the developing members 4C, 4M, 4Y, and 4K of the image forming units 6C, 6M, 6Y, and 6K and the cleaning members 5C, 5M, 5Y, and 5K. Transfer brushes 11C, 11M, 11Y, and 11K for applying a transfer bias are arranged on a surface (rear surface) that is in contact with and contacts the back side of the transfer conveyance belt 10 on the photoconductor side.
[0158]
Each of the image forming elements 6C, 6M, 6Y, and 6K is different in the color of the toner inside the developing device, and all the other components have the same configuration.
[0159]
In the color image forming apparatus having the configuration shown in FIG. 9, the image forming operation is performed as follows.
First, in each of the image forming elements 6C, 6M, 6Y, and 6K, the photoconductors 1C, 1M, 1Y, and 1K are charged by the charging members 2C, 2M, 2Y, and 2K that rotate in the arrow direction (the direction along the photoconductor). Then, an electrostatic latent image corresponding to the image of each color to be formed is formed by the laser beams 3C, 3M, 3Y, and 3K in an exposure unit (not shown) arranged inside the photoconductor. Next, the latent images are developed by the developing members 4C, 4M, 4Y, and 4K to form toner images.
[0160]
Developing members 4C, 4M, 4Y, and 4K are developing members that perform development with C (cyan), M (magenta), Y (yellow), and K (black) toners, respectively, and include four photoconductors 1C, 1M, and 1Y. 1K are superimposed on transfer paper.
[0161]
The transfer paper 7 is sent out of a tray by a paper feed roller 8, temporarily stopped by a pair of registration rollers 9, and sent to a transfer conveyance belt 10 at the same time as the image formation on the photosensitive member. The transfer paper 7 held on the transfer / conveyance belt 10 is conveyed, and the transfer of the toner image of each color is performed at a contact position (transfer portion) with each of the photoconductors 1C, 1M, 1Y, and 1K. The toner image on the photoconductor is transferred onto the transfer paper 7 by an electric field formed by a transfer bias applied to the transfer brushes 11C, 11M, 11Y, and 11K and a potential difference between the photoconductors 1C, 1M, 1Y, and 1K. You.
[0162]
Then, the recording paper 7 on which the four color toner images are superimposed through the four transfer units is conveyed to the fixing device 12, where the toner is fixed, and is discharged to a discharge unit (not shown). Further, residual toner remaining on each of the photoconductors 1C, 1M, 1Y, and 1K without being transferred by the transfer unit is collected by the cleaning devices 5C, 5M, 5Y, and 5K.
[0163]
In the example of FIG. 9, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the transfer paper transport direction. However, the order is not limited to this order, and the color order is arbitrarily set. In addition, when a black-only document is created, providing a mechanism for stopping the image forming elements (6C, 6M, 6Y) other than black can be particularly effectively used in the present invention. Further, in FIG. 9, the charging member is in contact with the photoreceptor, but by providing an appropriate gap (about 10 to 200 μm) between the two, the amount of wear of both can be reduced and the charging member Less toner filming and good use.
[0164]
The image forming means as described above may be fixedly incorporated in a copying machine, a facsimile, or a printer, but each electrophotographic element may be incorporated in the apparatus in the form of a process cartridge. The process cartridge is one device (part) that includes a photoconductor and further includes at least one of a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit.
[0165]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited by the examples. All parts are parts by weight.
First, a specific synthesis example of a crystalline titanyl phthalocyanine pigment having a maximum diffraction peak at a Bragg angle of 2θ of 27.2 ° ± 0.2 ° will be described.
[0166]
(Pigment Production Example 1)
292 parts of 1,3-diiminoisoindoline and 1800 parts of sulfolane are mixed, and 204 parts of titanium tetrabutoxide are added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After the reaction, the precipitate was filtered after standing to cool, washed with chloroform until the powder turned blue, then washed with methanol several times, further washed with hot water of 80 ° C. several times, and dried. Crude titanyl phthalocyanine was obtained.
[0167]
60 parts of the obtained crude titanyl phthalocyanine pigment subjected to the washing with hot water were stirred and dissolved in 1000 parts of 96% sulfuric acid at 3 to 5 ° C. and filtered. The obtained sulfuric acid solution was added dropwise to 35,000 parts of ice water with stirring, and the precipitated crystals were filtered and then repeatedly washed with water until the washing liquid became neutral, to obtain a water paste of titanyl phthalocyanine pigment.
[0168]
1500 parts of tetrahydrofuran was added to this water paste, and the mixture was stirred at room temperature. When the dark blue color of the paste changed to light blue, the stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filter were washed with tetrahydrofuran to obtain 98 parts of a pigment wet cake. This was dried at 70 ° C. under reduced pressure (5 mmHg) for 2 days to obtain 78 parts of titanyl phthalocyanine crystals. This is referred to as Pigment 1.
[0169]
A part of the water paste obtained in Pigment Production Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain low crystalline titanyl phthalocyanine powder.
[0170]
The X-ray diffraction spectra of the dried powder of the water paste obtained as described above and the titanyl phthalocyanine crystal (pigment 1) obtained in Pigment Production Example 1 were measured under the following conditions.
X-ray tube: Cu voltage: 40 kV Current: 20 mA
Scanning speed: 1 ° / min Scanning range: 3 ° to 40 ° Time constant: 2 seconds
[0171]
The X-ray diffraction spectrum of the dried powder of the water paste is shown in FIG. 10, and the X-ray diffraction spectrum of Pigment 1 is shown in FIG.
[0172]
As shown in FIG. 11, Pigment 1 has the maximum diffraction peak at 27.2 °, further has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has the lowest diffraction angle. A titanyl phthalocyanine crystal having a crystal form having a peak at 7.3 °, having no peak in the range of 7.4 ° to less than 9.4 °, and having no peak at 26.3 °. You can see that there is.
[0173]
(Comparative Example 1)
A dispersion having the following composition was prepared by bead milling under the following conditions (this is referred to as dispersion 1).
240 parts of titanyl phthalocyanine crystal (pigment 1) produced in Pigment Production Example 1
Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 160 parts
2-butanone 3600 parts
Using a zirconia ball having a diameter of 0.5 mm in a commercially available bead mill disperser (manufactured by VMA-GETZMANN GMBH: DISPERMAT SL, rotor diameter: 50 mm, dispersion chamber capacity: 125 ml), 2-butanone and pigment in which polyvinyl butyral was dissolved were all used. And the rotor speed is 3000r. p. m. For 300 minutes.
The flow rate when the number of revolutions of the motor for feeding liquid was set to the scale 5 was 1 liter / minute, but in the initial dispersion state under the above conditions, the flow rate was reduced to 0.3 liter / minute for about 8 minutes. In this state, the dispersion was performed for 300 minutes without changing the rotation speed of the rotor.
After the dispersion was completed, the mill base was discharged from the bead mill disperser, and 10300 parts of 2-butanone was further charged, and all the mill base remaining in the disperser was discharged simultaneously with the dilution to prepare a dispersion.
[0174]
(Example 1)
In Comparative Example 1, the number of revolutions of the liquid feeding motor was increased to the scale 8 so that the circulation flow rate was not reduced, and the dispersion was performed while decreasing the flow rate while maintaining the flow rate at 0.9 to 1 liter / min. / Min, the dispersion was performed in the same manner as in Comparative Example 1 except that the motor rotation speed was gradually returned, and finally the scale was set to 5 to perform dispersion, thereby preparing a dispersion liquid. Dispersion 2).
[0175]
(Example 2)
In Comparative Example 1, dispersion was performed by increasing the number of revolutions of the liquid feeding motor to scale 7 so as to keep the circulation flow rate from dropping while maintaining the flow rate at 0.6 to 0.8 liter / min. When the speed became 1 liter / min or more, the dispersion was performed in the same manner as in Comparative Example 1 except that the motor rotation speed was gradually returned, and finally the scale was set to 5 to perform dispersion, thereby preparing a dispersion liquid ( This is referred to as dispersion liquid 3).
[0176]
(Example 3)
In Comparative Example 1, the rotation speed of the liquid sending motor was increased to the scale 6 so that the circulation flow rate was not reduced, and the dispersion was performed while maintaining the flow rate at 0.4 to 0.5 liter / min to perform dispersion. When the speed became 1 liter / min or more, the dispersion was performed in the same manner as in Comparative Example 1 except that the motor rotation speed was gradually returned, and finally the scale was set to 5 to perform dispersion, thereby preparing a dispersion liquid ( This is referred to as dispersion liquid 4).
[0177]
(Example 4)
Dispersion was performed in the same manner as in Example 1 except that the dispersion medium was changed to zirconia balls having a diameter of 0.8 mm in Example 1 to prepare a dispersion (this is referred to as dispersion 5).
[0178]
(Comparative Example 2)
Dispersion was performed in the same manner as in Example 1 except that the dispersion medium was changed to zirconia balls having a diameter of 1.5 mm in Example 1, and a dispersion was prepared (this is referred to as dispersion 6).
The following evaluations were performed on the dispersions 1 to 6 prepared as described above. Table 1 shows the results. The flow rate in the table is the flow rate when the circulation flow rate is decreasing (in the initial dispersion state) (the same applies hereinafter).
・ Average particle size:
HORIBA, Ltd .: The volume average particle size was evaluated by CAPA700.
-Observation of coarse particles:
The dispersion was applied to a slide glass to prepare a sample for observation. Subsequently, the coating film was observed with a commercially available optical microscope (50 to 100 times) to observe the presence or absence of coarse particles.
-X-ray diffraction spectrum:
The dispersion was dried and powdered, and the X-ray diffraction spectrum was measured in the same manner as described above.
・ Evaluation of film formability:
A film was formed on the washed aluminum plate by the dip coating method, and the state of the coating film was observed.
[0179]
[Table 1]

[0180]
FIG. 12 shows an X-ray diffraction spectrum when a part of the crystal has undergone crystal transition (Comparative Example 2). The arrow in the figure is a new peak (26.3 °) not observed in the crystal of FIG.
[0181]
(Example 5)
A dispersion was prepared in the same manner as in Example 1 except that the solvent used in the dispersion of Example 1 was changed from 2-butanone to n-butyl acetate (this is referred to as dispersion 7).
[0182]
(Example 6)
A dispersion was prepared in the same manner as in Example 1 except that the solvent used in the dispersion of Example 1 was changed from 2-butanone to n-butanol (this is referred to as dispersion 8).
[0183]
(Example 7)
A dispersion was prepared in the same manner as in Example 1 except that the composition of the dispersion of Example 1 was changed to the one having the following composition (this is referred to as dispersion 9).
240 parts of titanyl phthalocyanine crystal (pigment 1) produced in Pigment Production Example 1
Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 160 parts
3,600 parts of tetrahydrofuran
36 parts of ion exchange water
[0184]
(Example 8)
A dispersion was prepared in the same manner as in Example 7 except that ion-exchanged water was removed from the dispersion of Example 7 (this is referred to as dispersion 10).
[0185]
(Example 9)
A dispersion was prepared in the same manner as in Example 1 except that polyvinyl butyral was removed from the dispersion of Example 1 (this is referred to as dispersion 11).
[0186]
The dispersions 7 to 11 prepared as described above were evaluated in the same manner as the dispersions 1 to 6. The results are shown in Table 2 together with the results of Example 1.
[0187]
[Table 2]

[0188]
As can be seen from Table 2, when 2-butanone (ketone-based solvent), n-butyl acetate (ester-based solvent), and tetrahydrofuran (ether-based solvent) are used as the dispersion solvent, a dispersion having good properties is obtained. However, when n-butanol (alcohol-based solvent), which is another solvent, was used, the result was slightly poor dispersion stability.
In addition, when ion-exchanged water was not added or when a binder resin was not added, there were cases where crystal stability was poor.
[0189]
(Pigment Production Example 2)
A pigment was prepared according to the method described in "Example 1" of JP-A-1-299874 (Japanese Patent No. 2512081). That is, the wet cake prepared in Pigment Production Example 1 was dried, 200 g of the dried product was added to 1000 g of polyethylene glycol, and a sand mill was performed together with 20,000 g of glass beads. After the crystal transition, the pigment was sequentially washed with dilute sulfuric acid and an aqueous solution of ammonium hydroxide, and dried to obtain a pigment (this is referred to as pigment 2).
[0190]
(Pigment Production Example 3)
A pigment was prepared according to the method described in "Production Example 1" of JP-A-3-269064 (Japanese Patent No. 2584682). That is, the wet cake prepared in Pigment Preparation Example 1 was dried, and 200 g of the dried product was stirred (50 ° C.) for 1 hour in a mixed solvent of 2000 g of ion-exchanged water and 200 g of monochlorobenzene, followed by methanol and ion-exchanged water. The pigment was washed and dried to obtain a pigment (this is referred to as Pigment 3).
[0191]
(Pigment Production Example 4)
A pigment was prepared according to the method described in "Production Examples" in JP-A-2-8256 (JP-B-7-91486). That is, 196 g of phthalodinitrile and 1500 ml of 1-chloronaphthalene are stirred and mixed, and 44 ml of titanium tetrachloride is added dropwise under a nitrogen stream. After the completion of the dropwise addition, the temperature was gradually raised to 200 ° C, and the reaction was carried out with stirring for 3 hours while maintaining the reaction temperature between 200 ° C and 220 ° C. After the completion of the reaction, the mixture was left to cool to 130 ° C., filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, washed several times with methanol, and further washed with hot water at 80 ° C. After washing twice, it was dried to obtain a pigment (this is referred to as Pigment 4).
[0192]
(Pigment Production Example 5)
A pigment was prepared according to the method described in "Synthesis Example 1" of JP-A No. 64-17066 (Japanese Patent Publication No. 7-97221). That is, 200 parts of α-type TiOPc were subjected to a crystal conversion treatment at 100 ° C. for 10 hours with a sand grinder together with 400 g of sodium chloride and 200 g of acetophenone. This was washed with ion-exchanged water and methanol, purified with a dilute aqueous sulfuric acid solution, washed with ion-exchanged water until the acid content disappeared, and then dried to obtain a pigment (this is referred to as pigment 5).
[0193]
(Pigment Production Example 6)
A pigment was prepared according to the method described in "Example 1" of JP-A-11-5919 (Japanese Patent No. 3003664). That is, after 204 parts of O-phthalodinitrile and 76 parts of titanium tetrachloride were heated and reacted in 500 parts of quinoline at 200 ° C. for 2 hours, the solvent was removed by steam distillation, and a 2% aqueous solution of hydrochloric acid was added, followed by 2% aqueous hydroxide. The product was purified with an aqueous sodium solution, washed with methanol and N, N-dimethylformamide, and dried to obtain titanyl phthalocyanine. 200 parts of this titanyl phthalocyanine is gradually dissolved in 40 parts of 98% sulfuric acid at 5 ° C., and the mixture is stirred for about 1 hour while maintaining the temperature at 5 ° C. or less. Subsequently, the sulfuric acid solution is slowly poured into 8000 parts of ice water with high-speed stirring, and the precipitated crystals are filtered. The crystals are washed with distilled water until no more acid remains, to obtain a wet cake. The cake was stirred in 10,000 parts of THF for about 5 hours, filtered, washed with THF, and dried to obtain a pigment (this is referred to as Pigment 6).
[0194]
(Pigment Production Example 7)
A pigment was prepared according to the method described in "Synthesis Example 2" of JP-A-3-255456 (Japanese Patent No. 3005052). That is, 400 parts of the wet cake prepared in Pigment Preparation Example 1 was mixed with 600 parts of sodium chloride and 280 parts of diethylene glycol, and milling was performed in an automatic mortar under heating at 80 ° C. for 60 hours. Next, the treated product was sufficiently washed with water to completely remove sodium chloride and diethylene glycol. After drying under reduced pressure, 8000 parts of cyclohexanone and glass beads having a diameter of 1 mm were added, and the mixture was treated by a sand mill for 30 minutes to obtain a pigment (this is referred to as pigment 7).
[0195]
X-ray diffraction spectra of the pigments 2 to 7 produced in the above pigment production examples 2 to 7 were measured in the same manner as described above, and it was confirmed that the spectra were the same as those described in the respective publications. Table 3 shows the characteristics of the X-ray diffraction spectrum and the peak position of the X-ray diffraction spectrum of the pigment obtained in Pigment Production Example 1.
[0196]
[Table 3]

[0197]
(Example 10)
A dispersion was prepared in the same manner as in Example 1 except that pigment 2 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 12).
[0198]
(Example 11)
A dispersion was prepared in the same manner as in Example 1 except that pigment 3 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 13).
[0199]
(Example 12)
A dispersion was prepared in the same manner as in Example 1 except that the pigment 4 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 14).
[0200]
(Example 13)
A dispersion was prepared in the same manner as in Example 1 except that pigment 5 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 15).
[0201]
(Example 14)
A dispersion was prepared in the same manner as in Example 1 except that pigment 6 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 16).
[0202]
(Example 15)
A dispersion was prepared in the same manner as in Example 1 except that pigment 7 was used instead of the titanyl phthalocyanine crystal (pigment 1) used in Example 1 (these are referred to as dispersion 17).
The dispersions 12 to 17 produced as described above were evaluated in the same manner as in Example 1, and are shown in Table 4 together with the results of Example 1.
[0203]
[Table 4]

[0204]
As can be seen from Table 4, even when a titanyl phthalocyanine crystal having a crystal type different from that of the pigment 1 is used, the dispersion for controlling the output of the liquid sending member is controlled so that the circulation flow rate is in an appropriate range in the initial dispersion state. By doing so, it was possible to prepare a dispersion liquid having no crystal transition and having high dispersion stability without coarse particles.
[0205]
(Preparation of photoconductor)
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 compositions are sequentially applied to an aluminum cylinder having a diameter of 60 mm (JIS 1050) and dried, and a 3.5 μm undercoat layer is formed. A 0.2 μm charge generation layer and a 19 μm charge transport layer were formed to produce a laminated photoreceptor (this is referred to as photoreceptor 1).
[0206]
[Coating solution for undercoat layer]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo) 70 parts
Alkyd resin (Beccolite M6401-50-S
(Solid content 50%), manufactured by Dainippon Ink and Chemicals, Inc. 15 parts
Melamine resin (Super Beckamine L-121-60
(Solid content 60%), manufactured by Dainippon Ink & Chemicals, Inc.) 10 parts
2-butanone 100 parts
[0207]
[Coating solution for charge generation layer]
Dispersion 1 described above was used.
[0208]
[Charge transport layer coating solution]
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
Embedded image

80 parts of tetrahydrofuran
[0209]
Photoconductor production example 2:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 2 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0210]
Photoconductor production example 3:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1, except that Dispersion Liquid 3 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0211]
Photoconductor production example 4:
A photoreceptor was produced in the same manner as in Photoreceptor Production Example 1 except that Dispersion Liquid 4 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Production Example 1. ).
[0212]
Photoconductor Production Example 5:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 5 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0213]
Photoconductor Production Example 6:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 6 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1 (this is referred to as Photoreceptor 6). ).
[0214]
Photoconductor production example 7:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 7 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0215]
Photoconductor Production Example 8:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1, except that Dispersion Liquid 8 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0216]
Photoconductor Production Example 9:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 9 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Production Example 1. ).
[0217]
Photoconductor Production Example 10:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1, except that Dispersion Liquid 10 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0218]
Photoconductor Production Example 11:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion Liquid 11 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoconductor Production Example 1. ).
[0219]
Photoconductor Production Example 12:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion Liquid 12 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoconductor Production Example 1. ).
[0220]
Photoconductor Production Example 13:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion Liquid 13 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Photoconductor Preparation Example 1. ).
[0221]
Photoconductor Production Example 14:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1 except that Dispersion Liquid 14 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Photoreceptor Preparation Example 1. ).
[0222]
Photoconductor Production Example 15:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion Solution 15 was used instead of Dispersion Solution 1 as the charge generation layer coating liquid in Photoconductor Production Example 1. ).
[0223]
Photoconductor Production Example 16:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 1, except that Dispersion Liquid 16 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Preparation Example 1. ).
[0224]
Photoconductor Production Example 17:
A photoreceptor was produced in the same manner as in Photoreceptor Production Example 1 except that Dispersion Liquid 17 was used instead of Dispersion Liquid 1 as the charge generation layer coating liquid in Photoreceptor Production Example 1. ).
[0225]
(Examples 16 to 30 and Comparative Examples 3 to 4)
The photoconductors 1 to 18 produced as described above were mounted on a commercially available plain paper copying machine (Ricoh: imageioMF4550). Another power source was provided outside the copying machine as an AC power source.
The image exposure light source was a 780 nm semiconductor laser (image writing with a polygon mirror).
As a charging member, a non-contact close-positioning type charging roller as shown in FIG. 6 (a 50 μm thick insulating tape is wound around the non-image portions at both ends, and a 50 μm (Arranged so as to have a gap), and an image was output under the following charging conditions.
Charging conditions:
DC bias: -900V
AC bias: 2.3 kV (peaktop), frequency 2 kHz
[0226]
Using a chart with a writing rate of 6%, printing was continuously performed on 5000 sheets, and the images at the initial stage and after 5000 sheets were evaluated. In the image evaluation, a solid white image was output at the initial stage and after 5,000 sheets, and the background stain was evaluated (evaluated according to the following rank). Further, a halftone image including a black circle (solid black) having a diameter of 1 cm at the four corners and the center was output at the initial stage and after 5000 sheets, and the image was evaluated.
Table 5 shows the results.
[0227]
[Table 5]

Ground dirt rank:
5: Almost no soil, 4: Slight, 3: Actual use limit level, 2 or less: Level that cannot withstand actual use
[0228]
Photoconductor Production Example 18:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2, except that the coating liquid for the charge transport layer in Photoconductor Preparation Example 2 was changed to the one having the following composition (this is referred to as Photoconductor 18).
[Charge transport layer coating solution]
Polymer charge transport material of the following composition
(Weight average molecular weight: about 140000) 10 parts
Embedded image

0.5 parts of additives with the following structure
Embedded image

100 parts of tetrahydrofuran
[0229]
Photoconductor Production Example 19:
Same as Photoreceptor Preparation Example 2 except that the thickness of the charge transport layer in Photoreceptor Preparation Example 2 was set to 17 μm, a protective layer coating solution having the following composition was applied on the charge transport layer and dried, and a protective layer of 2 μm was provided. Then, a photoreceptor was prepared (this is referred to as a photoreceptor 19).
[Protective layer coating solution]
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10¹²Ω · cm,
(Average primary particle size: 0.4 μm) 4 parts
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0230]
Photoconductor Production Example 20:
Same as Photoreceptor Preparation Example 2 except that the thickness of the charge transport layer in Photoreceptor Preparation Example 2 was set to 17 μm, a protective layer coating solution having the following composition was applied on the charge transport layer and dried, and a protective layer of 2 μm was provided. Then, a photoreceptor was prepared (this is referred to as a photoreceptor 20).
[Protective layer coating solution]
Polymer charge transport material of the following structural formula
(Weight average molecular weight: about 140000) 17 parts
Embedded image

Alumina fine particles (specific resistance: 2.5 × 10¹²Ω · cm,
(Average primary particle size: 0.4 μm) 4 parts
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0231]
Photoconductor Production Example 21:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 20, except that the alumina fine particles in the protective layer coating solution in Photoreceptor Preparation Example 20 were changed to the following.
Titanium oxide fine particles (specific resistance: 1.5 × 10¹⁰Ω · cm,
(Average primary particle size: 0.5 μm) 4 parts
[0232]
Photoconductor Production Example 22:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 20, except that the alumina fine particles in the protective layer coating liquid in Photoreceptor Preparation Example 20 were changed to the following.
Tin oxide-antimony oxide powder 4 parts
(Specific resistance: 10⁶Ω · cm, average primary particle size 0.4 μm)
[0233]
Photoconductor Production Example 23:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 2 except that the charge transport layer coating solution in Photoreceptor Preparation Example 2 was changed to the one having the following composition (this is referred to as Photoreceptor 23).
[Charge transport layer coating solution]
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
Embedded image

80 parts of toluene
[0234]
Photoconductor Production Example 24:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 2 except that the charge transport layer coating liquid in Photoreceptor Preparation Example 2 was changed to one having the following composition (this is referred to as Photoreceptor 24).
[Charge transport layer coating solution]
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
Embedded image

80 parts of methylene chloride
[0235]
Photoconductor production example 25:
The aluminum cylinder (JIS 1050) in Photoreceptor Preparation Example 2 was subjected to the following anodic oxide film treatment, and then a charge generation layer and a charge transport layer were provided in the same manner as in Photoreceptor Preparation Example 2 without providing an undercoat layer. (This is referred to as a photoreceptor 25).
[Anodic oxide film treatment]
The support was mirror-polished, degreased and washed with water, immersed in an electrolytic bath at a liquid temperature of 20 ° C. and 15 vol% of sulfuric acid, and subjected to an anodic oxide film treatment at an electrolytic voltage of 15 V for 30 minutes. After washing with water, a sealing treatment was performed with a 7% nickel acetate aqueous solution (50 ° C.). Thereafter, the substrate was washed with pure water to obtain a support having a 7 μm anodic oxide film formed thereon.
[0236]
(Examples 31 to 39)
The photoreceptors 2, 18 to 25 produced as described above were mounted on a commercially available plain paper copying machine (made by Ricoh: imagioMF4550). A copying machine (image writing with a polygon mirror) was used as the AC power supply.
As a charging member, a non-contact close-positioning type charging roller as shown in FIG. 6 (a 50 μm thick insulating tape is wound around the non-image portions at both ends, and a 50 μm (Arranged so as to have a gap), and an image was output under the following charging conditions.
Charging conditions:
DC bias: -900V
AC bias: 2.3 kV (peaktop), frequency 2 kHz
[0237]
Using a chart with a writing rate of 6%, printing was continuously performed on 10,000 sheets, and images at the initial stage and after 10,000 sheets were evaluated. In the image evaluation, a solid white image was output at the initial stage and after 10,000 copies, and the background stain was evaluated (evaluated according to the following rank). Further, a halftone image including a black circle (solid black) having a diameter of 1 cm at the four corners and the center was output at the initial stage and after 10,000 sheets, and the image was evaluated.
Table 6 shows the results.
[0238]
[Table 6]

Ground dirt rank:
5: Almost no soil, 4: Slight, 3: Actual use limit level, 2 or less: Level that cannot withstand actual use
[0239]
(Example 40)
In the evaluation of Example 31, the evaluation was performed in the same manner as in Example 31 except that the charging conditions were changed to the following conditions. Table 7 shows the results.
Charging conditions:
DC bias: -1700 V (set so that the potential of the unexposed portion on the surface of the photoconductor becomes -900 V)
[0240]
(Example 41)
In the evaluation of Example 40, the charging roller used was changed to the contact type (the roller material and the like were the same, and the insulating tapes at both ends were not wound), and an image was output under the following charging conditions. Table 7 shows the results.
Charging conditions:
DC bias: -1650 V (set so that the potential of the unexposed portion on the surface of the photoconductor becomes -900 V)
[0241]
(Example 42)
In the evaluation of Example 40, the charging roller used was changed to the contact type (the roller material and the like were the same, and the insulating tapes at both ends were not wound), and an image was output under the following charging conditions. Table 7 shows the results.
Charging conditions:
DC bias: -900V
AC bias: 2.3 kV (peaktop), frequency 2 kHz
[0242]
(Example 43)
In the evaluation of Example 31, the evaluation was performed in the same manner as in Example 31 except that the gap was changed to 150 μm by changing the thickness of the insulating tape. Table 7 shows the results.
[0243]
(Example 44)
In the evaluation of Example 31, the evaluation was performed in the same manner as in Example 31 except that the thickness of the insulating tape was changed and the gap was changed to 250 μm. Table 7 shows the results.
[0244]
(Example 45)
In the evaluation of Example 31, evaluation was performed using a scorotron charger as a charging member to be used. At this time, the copier used for the test was modified so that a scorotron charger could be mounted.
Charging conditions:
DC bias: -6.5 kV
[0245]
[Table 7]

Ground dirt rank:
5: Almost no soil, 4: Slight, 3: Actual use limit level, 2 or less: Level that cannot withstand actual use
[0246]
Photoconductor Production Example 26:
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the support used in Photoconductor Production Example 1 was changed to an aluminum cylinder (JIS 1050) having a diameter of 30 mm (this is referred to as Photoconductor 26).
[0247]
Photoconductor Production Example 27:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 26 except that Dispersion 2 was used instead of Dispersion 1 used in Photoreceptor Preparation Example 26 (this is referred to as Photoreceptor 27).
[0248]
Photoconductor Production Example 28:
A photoreceptor was prepared in the same manner as in Photoreceptor Preparation Example 26 except that Dispersion 7 was used instead of Dispersion 1 used in Photoreceptor Preparation Example 26 (this is referred to as Photoreceptor 28).
[0249]
(Example 46 and Comparative Examples 5 and 6)
The photoconductors 26 to 28 manufactured as described above are mounted on an image forming apparatus cartridge as shown in FIG. 8 and mounted on a tandem type full color image forming apparatus as shown in FIG. 9 (all image forming elements). The same photoreceptor is mounted on the same), an image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), and a 50 μm thick insulating tape is applied to both ends of a charging roller as shown in FIG. 6 as a charging member. An image was output under the following charging conditions using the wound charging member for proximity arrangement (the gap between the photosensitive member and the charging member surface was 50 μm).
Charging conditions:
DC bias: -800V
AC bias: 2.2 kV (peak to peak), frequency: 1.5 kHz
[0250]
Using a full-color chart with a writing rate of 6%, printing was continuously performed on 5000 sheets, and the images at the initial stage and after 5000 sheets were evaluated. In the image evaluation, a solid white image was output at the initial stage and after 5,000 sheets, and the background stain was evaluated. The color reproducibility after 5,000 sheets was evaluated using a chart for evaluating color reproducibility. Table 8 shows the results.
[0251]
[Table 8]

Ground dirt rank:
5: Almost no soil, 4: Slight, 3: Actual use limit level, 2 or less: Level that cannot withstand actual use
[0252]
Subsequently, it will be verified whether or not the lowest angle peak of 7.3 ° of the Bragg angle θ, which is a feature of the titanyl phthalocyanine crystal used in the present invention, is the same as the lowest angle of known materials of 7.5 °.
[0253]
(Pigment Production Example 8)
The same treatment as in Synthesis Example 1 was carried out except that the crystal conversion solvent in Pigment Production Example 1 was changed from methylene chloride to 2-butanone, to obtain titanyl phthalocyanine crystals.
As in the case of FIG. 11, the X-ray diffraction spectrum of the titanyl phthalocyanine crystal produced in Pigment Production Example 8 was measured. This is shown in FIG. From FIG. 13, the lowest angle in the X-ray diffraction spectrum of the titanyl phthalocyanine crystal produced in Pigment Production Example 8 is different from the lowest angle (7.3 °) of the titanyl phthalocyanine produced in Synthesis Example 1; It can be seen that it exists at 5 °.
[0254]
(Measurement example 1)
The pigment (lowest angle 7.3 °) obtained in Pigment Production Example 1 was prepared in the same manner as the pigment (having the maximum diffraction peak at 7.5 °) described in JP-A-61-239248. % By weight and mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as above. The X-ray diffraction spectrum of Measurement Example 1 is shown in FIG.
[0255]
(Measurement example 2)
The pigment (minimum angle 7.5 °) obtained in Pigment Production Example 8 was prepared in the same manner as the pigment (having the maximum diffraction peak at 7.5 °) described in JP-A-61-239248. % By weight and mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as described above. The X-ray diffraction spectrum of Measurement Example 2 is shown in FIG.
[0256]
In the spectrum of FIG. 14, two independent peaks of 7.3 ° and 7.5 ° exist on the low angle side, and it can be seen that at least the peaks of 7.3 ° and 7.5 ° are different. . On the other hand, in the spectrum of FIG. 13, the low-angle side peak exists only at 7.5 °, which is clearly different from the spectrum of FIG.
From the above, it can be seen that the lowest angle peak of 7.3 ° in the titanyl phthalocyanine crystal of the present invention is different from the peak of 7.5 ° in the known titanyl phthalocyanine crystal.
[0257]
【The invention's effect】
According to the present invention, in view of the dispersion of the titanyl phthalocyanine crystal, which has low crystal stability and is difficult to be finely divided, using a circulation type bead mill dispersion device, circulation due to pigment clogging at the outlet of the dispersion chamber at the initial stage of circulation dispersion. In order to prevent a decrease in the flow rate and to maintain the flow rate within a predetermined range, the dispersion is performed under a specific condition in which the output of a circulation member such as a pump that sends the liquid to the dispersion chamber is larger than a steady state, so that the crystal stability and The relationship of the trade-off of atomization could be eliminated. As a result, a method for producing a dispersion liquid containing titanyl phthalocyanine crystals having high crystal stability (less crystal transition) and small particle size is provided. This dispersion is rich in storage stability, has good film-forming properties, and is formed into fine particles while maintaining the characteristics peculiar to the titanyl phthalocyanine crystal. Therefore, a photoreceptor manufactured using this dispersion is a stable electrophotographic photoreceptor that does not lose high sensitivity and does not cause a decrease in chargeability and a rise in residual potential even when repeatedly used. Further, an electrophotographic photoreceptor with less occurrence of abnormal images even when used repeatedly is provided.
Further, a stable image forming apparatus and a process cartridge for the image forming apparatus, which can perform high-speed printing and generate few abnormal images, are provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of a bead mill dispersion apparatus used for preparing a dispersion of the present invention.
FIG. 2 is a diagram showing the inside of a dispersion chamber 2 of the bead mill dispersion device shown in FIG.
FIG. 3 is a diagram showing a configuration example of an example of the electrophotographic photosensitive member of the present invention.
FIG. 4 is a diagram showing another configuration example of the electrophotographic photosensitive member of the present invention.
FIG. 5 is a diagram for explaining an image forming process of the present invention.
FIG. 6 is a diagram illustrating an example of a proximity charging mechanism in which a gap forming member is arranged on a charging unit side of the image forming apparatus.
FIG. 7 is a view for explaining another example of the image forming process of the present invention.
FIG. 8 is a diagram illustrating an example of a process cartridge for an image forming apparatus.
FIG. 9 is a schematic diagram illustrating a color image forming apparatus.
FIG. 10 is an X-ray diffraction spectrum of a dry powder of a water paste obtained in Pigment Preparation Example 1.
FIG. 11 is an X-ray diffraction spectrum of Pigment 1.
FIG. 12 is an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Example 2.
FIG. 13 is an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Pigment Production Example 8.
FIG. 14 is an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Measurement Example 1.
FIG. 15 is an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Measurement Example 2.
[Explanation of symbols]
(In FIGS. 1 and 2)
1 motor
2 Distribution room
3 Flow meter
4 Circulation tank
5 Circulation pump
6 Piping
7 Dispersion room fixed base
10 Distributed media
11 slit
12 Circulation outlet side piping
13 Wall of dispersion room
14 Rotor
15 Circulation inlet side piping
16 motor
(In FIGS. 3 and 4)
31 conductive support
35 charge generation layer
37 charge transport layer
39 Protective layer
(In FIG. 6)
29 Photoconductor
30 charging roller
31 Gap forming member
32 metal shaft
33 Image formation area
34 Non-image forming area
(In FIG. 9)
1C, 1M, 1Y, 1K photoconductor
2C, 2M, 2Y, 2K Charging member
3C, 3M, 3Y, 3K laser light
4C, 4M, 4Y, 4K developing member
5C, 5M, 5Y, 5K Cleaning member
6C, 6M, 6Y, 6K image forming element
10 Transfer belt
11C, 11M, 11Y, 11K transfer brush
12 Fixing device

Claims (22)

In a method of producing a dispersion containing titanyl phthalocyanine crystals by a circulation type bead mill dispersion apparatus using a dispersion medium having a diameter of 1 mm or less, dispersion is performed while measuring a circulation flow rate, and the circulation flow rate is reduced to a predetermined amount from the start of dispersion. A method for producing a dispersion, wherein the output of a circulating member such as a pump for feeding a liquid to a dispersion chamber is made larger than a steady state until the dispersion reaches a steady state. 2. The dispersion according to claim 1, wherein the circulating flow is in a range of 50 to 100% of a steady state until the circulating flow reaches a predetermined amount from the start of dispersion. How to make. The titanyl phthalocyanine crystal has a maximum diffraction peak at at least 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to CuKα characteristic X-ray (wavelength 1.542 °). Item 3. The method for producing a dispersion according to Item 1 or 2. The titanyl phthalocyanine crystal further has a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα, which is mainly at 9.4 °, 9.6 ° and 24.0 °. A peak at 7.3 ° as a diffraction peak on the lowest angle side and no peak in a range from 7.4 ° to less than 9.4 °. 3. The method for producing the dispersion according to 3. The method according to claim 3 or 4, wherein the titanyl phthalocyanine further has no peak at 26.3 °. In the method for producing a dispersion, the dispersion solvent according to any one of claims 1 to 5, wherein at least one selected from a ketone solvent, an ester solvent, and an ether solvent is used. Production method. The method for producing a dispersion according to any one of claims 1 to 6, wherein a binder resin is used in dispersing the titanyl phthalocyanine crystal in the method for producing a dispersion. The method for producing a dispersion according to any one of claims 1 to 6, wherein water is used in combination when dispersing the titanyl phthalocyanine crystal in the method for producing a dispersion. An electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated on a conductive support, wherein the charge generation layer uses a dispersion prepared by the method according to any one of claims 1 to 8. An electrophotographic photoreceptor characterized by being formed by: The electrophotographic photoreceptor according to claim 9, wherein the charge transporting layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain. The electrophotographic photosensitive member according to claim 9, wherein a protective layer is laminated on the charge transport layer. The electrophotographic photosensitive member according to claim 11, wherein the protective layer contains a specific resistance ¹⁰ 10 Ω · cm or more inorganic pigments or metal oxides. The electrophotographic photoreceptor according to any one of claims 9 to 12, wherein the charge transport layer is formed using a non-halogen solvent. 14. The electrophotographic photoreceptor according to claim 13, wherein at least one selected from a cyclic ether and an aromatic hydrocarbon is used as the non-halogen solvent. The electrophotographic photoreceptor according to any one of claims 9 to 14, wherein the surface of the conductive support is anodized. An image forming apparatus comprising at least a charging unit, an exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 9 to 15. Characteristic image forming apparatus. 16. An image forming apparatus in which at least a plurality of image forming elements including a charging unit, an exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member are arranged, wherein the electrophotographic photosensitive member is any one of claims 9 to 15. An image forming apparatus comprising a photographic photosensitive member. 18. The image forming apparatus according to claim 16, wherein the charging unit uses a contact charging system. 18. The image forming apparatus according to claim 16, wherein a non-contact proximity arrangement method is used for the charging unit. 20. The image forming apparatus according to claim 19, wherein a gap between the charging member used for the charging unit and the photoconductor is 10 μm or more and 200 μm or less. 21. The image forming apparatus according to claim 16, wherein an AC voltage is superimposed on a DC voltage and applied to the charging unit. 16. A process cartridge for an image forming apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 9 to 15. Process cartridge for equipment.

Images