JP2004083859A - Titanyl phthalocyanine crystal, method of producing titanyl phthalocyanine crystal, electrophotographic photoreceptor, electrophotographic method, electrophotographic apparatus and process cartridge for the electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide titanyl phthalocyanine crystal which gives a dispersion having high stability of the crystals and small particle sizes in preparing the dispersion and a method of producing the crystal, a stable electrophotographic photosensor which generates little abnormal images by repeated uses and does not cause reduction of electrostatic charge and rise of residual potential, and a stable electrophotographic method and an electrophotographic apparatus by which a high-speed printing is possible and which generate little abnormal images. <P>SOLUTION: The titanyl phthalocyanine crystal has a maximum diffraction peak at least at 27.2° as the diffraction peak (±0.2°) of Bragg angle 2θ to characteristic X-ray (wavelength 1.542Å) of CuKa, main peaks at 9.4°, 9.6° and 24.0° and 7.3° as the diffraction peak in the smallest angle region and no peaks between 7.3° and 9.4°, and ≤0.2μm average size of primary particles. The electrophotographic photosensor and the apparatus for generating images are provided by using the crystal. <P>COPYRIGHT: (C)2004,JPO

Description

（Ｉ）式
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は組成を表わし、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表わし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わされる２価基を表わす。なお、（Ｉ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００５９】
【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わす。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価基を表わす。）または、
【００６０】
【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わす）を表わす。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。）
【００６１】
【化４】

（ＩＩ）式
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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＩＩ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６２】
【化５】

（ＩＩＩ）式
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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＩＩＩ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６３】
【化６】

（ＩＶ）式
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、Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＩＶ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６４】
【化７】

（Ｖ）式
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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（Ｖ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６５】
【化８】

（ＶＩ）式
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、ビニレン基を表わし同一であっても異なってもよい。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＶＩ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６６】
【化９】

（ＶＩＩ）式
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わし，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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＶＩＩ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６７】
【化１０】

（ＶＩＩＩ）式
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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＶＩＩＩ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６８】
【化１１】

（ＩＸ）式
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わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（ＩＸ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００６９】
【化１２】

（Ｘ）式
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_３０，Ａｒ_３１は同一又は異なるアリレン基を表わす。Ｘ，ｋ，ｊおよびｎは、（Ｉ）式の場合と同じである。なお、（Ｘ）式は２つの共重合種が交互共重合体の形で記載されているが、ランダム共重合体でもよい。
【００７０】
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。
【００７１】
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。
【００７２】
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できる。
【００７３】
本発明において電荷輸送層（４７）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。
【００７４】
結着樹脂としては、先に電荷輸送層（４７）で挙げた結着樹脂をそのまま用いるほかに、電荷発生層（４５）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、電荷輸送物質の量は０〜１９０重量部が好ましく、さらに好ましくは５０〜１５０重量部である。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。
【００７５】
本発明の電子写真感光体には、導電性支持体（４１）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。
【００７６】
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。
【００７７】
本発明の感光体においては、感光層保護の目的で、保護層（４９）が感光層の上に設けられることもある。保護層（４９）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。
【００７８】
保護層（４９）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。
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。更に、この中でも六方ちょう密構造を有するα−アルミナが最も有効に使用できる。
【００７９】
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、好ましくは３０重量％以下程度が良好である。
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。
【００８０】
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。
【００８１】
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。
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は安定化している。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。
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。
【００８２】
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。
【００８３】
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号公報の第１図、特開平５−１１３６８８号公報の第１図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言うところの比抵抗値と定義するものである。
【００８４】
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）を使用した。
【００８５】
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。表面処理剤としては、従来用いられている表面処理剤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。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。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。
【００８６】
また、保護層（４９）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。ここで言う濃度とは、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。
【００８７】
保護層のフィラー以外の成分を高分子だけで構成することにより、機械的な耐摩耗性を向上させるだけでなく、化学的な安定性を高めることもできる。高分子は低分子に比べて化学的な反応性に乏しく、帯電部材から発生する酸化性ガスへの耐性、あるいは放電によるスパッタリング効果に対する耐性も高い。保護層のように耐摩耗性の高い膜を表面に有する場合、繰り返し使用での画像ボケの問題が非常に顕著になる。これは、感光体表面に、酸化性ガスの吸着や低抵抗物質の付着（吸着）が起こるためであると考えられるが、上述のようにフィラー及び高分子成分だけから構成される保護層を採用した場合には、吸着サイトが減少することになり、画像ボケに対して高い効果を示すものである。
【００８８】
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、以上の他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。
【００８９】
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、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。
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。
【００９０】
また、フルカラー機もタンデム方式のものが主流になりつつあり、印刷速度が非常に向上してきた。このため、ビジネス文書の出力も多くなってきており、例えば会社のロゴを使用したような書式（書面）を出力するケースも増えている。このような場合には、特定の箇所にだけ印字が行なわれるため、感光体使用の偏りは一段と大きくなる。
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。
【００９１】
本発明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。
【００９２】
次に、図面を用いて本発明の電子写真方法ならびに電子写真装置を詳しく説明する。
図６は、本発明の電子写真プロセスおよび電子写真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６において、感光体（２１）は導電性支持体上に一次粒子の平均粒子サイズが０．２μｍ以下である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（２３）、転写前チャージャー（２７）、転写チャージャー（３０）、分離チャージャー（３１）、クリーニング前チャージャー（３３）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。帯電部材は、感光体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。特に、タンデム型のフルカラー画像形成装置においては、モノクロ画像形成装置の場合に発生する帯電ムラによるハーフトーン画像の濃度ムラの問題に加え、カラーバランス（色再現性）の低下という大きな問題につながる。直流成分に交流成分を重畳することにより、前記問題点は大きく改善されるものであるが、交流成分の条件（周波数、ピーク間電圧）が大きすぎる場合には、感光体へのハザードが大きくなり、感光体の劣化を早めてしまう場合がある。このため、交流成分の重畳は必要最低限にとどめるべきである。
【００９３】
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。
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。このギャップは、大きすぎた場合には帯電が不安定になりやすく、また小さすぎた場合には、感光体に残留したトナーが存在する場合に、帯電部材表面が汚染されてしまう可能性がある。したがって、ギャップは１０〜２００μｍ、好ましくは１０〜１００μｍの範囲が適当である。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チャージ・ワイヤータイプの帯電器、接触方式の帯電ローラー、帯電ブラシ、帯電ブレードなどの接触帯電部材とは区別されるものである。
【００９４】
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７に示す。
【００９５】
転写手段には、一般に上記の帯電器が使用できるが、図６に示されるように転写チャージャー（３０）と分離チャージャー（３１）を併用したものが効果的である。
また、画像露光部（２５）の光源にはＬＤもしくはＬＥＤが用いられる。除電ランプ（２２）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。
かかる光源等は、図６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。
【００９６】
さて、現像ユニット（２６）により感光体（２１）上に現像されたトナーは、転写紙（２９）に転写されるが、全部が転写されるわけではなく、感光体（２１）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（３４）およびブレード（３５）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。
【００９７】
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。
【００９８】
図８には、本発明による電子写真プロセスの別の例を示す。感光体（６１）は導電性支持体上に、一次粒子の平均粒子サイズが０．２μｍ以下である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（６２ａ），（６２ｂ）により駆動され、帯電器（６３）による帯電、光源（６４）による像露光、現像（図示せず）、帯電器（６５）を用いる転写、光源（６６）によるクリーニング前露光、ブラシ（６７）によるクリーニング、光源（６８）による除電が繰返し行なわれる。図８においては、感光体（６１）（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（６４）は、ＬＤもしくはＬＥＤが好ましく用いられる。
【００９９】
以上の図示した電子写真プロセスは、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８において感光層側よりクリーニング前露光を行なっているが、これは透光性支持体側から行なってもよいし、また、除電光の照射を支持体側から行なってもよい。
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。
【０１００】
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９に示すものが挙げられる。感光体（７６）は導電性支持体上に一次粒子の平均粒子サイズが０．２μｍ以下である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。
【０１０１】
図１０は、本発明のタンデム方式のフルカラー電子写真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１０において、符号（１Ｃ）、（１Ｍ）、（１Ｙ）及び（１Ｋ）はドラム状の感光体であり、この感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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）及び（２Ｋ）、現像部材（４Ｃ）、（４Ｍ）、（４Ｙ）及び（４Ｋ）、クリーニング部材（５Ｃ）、（５Ｍ）、（５Ｙ）及び（５Ｋ）が配置されている。帯電部材（２Ｃ）、（２Ｍ）、（２Ｙ）及び（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）及び（２Ｋ）と、現像部材（４Ｃ）、（４Ｍ）、（４Ｙ）及び（４Ｋ）の間の感光体表面に図示しない露光部材からのレーザー光（３Ｃ）、（３Ｍ）、（３Ｙ）及び（３Ｋ）が照射され、感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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）及び（１Ｋ）を中心とした４つの画像形成要素（６Ｃ）、（６Ｍ）、（６Ｙ）及び（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。転写搬送ベルト（１０）は各画像形成ユニット（６Ｃ）、（６Ｍ）、（６Ｙ）及び（６Ｋ）の現像部材（４Ｃ）、（４Ｍ）、（４Ｙ）及び（４Ｋ）とクリーニング部材（５Ｃ）、（５Ｍ）、（５Ｙ）及び（５Ｋ）の間で感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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）及び（１１Ｋ）が配置されている。各画像形成要素（６Ｃ）、（６Ｍ）、（６Ｙ）及び（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。
【０１０２】
図１０に示す構成のカラー電子写真装置において、画像形成動作は次のようにして行なわれる。まず、各画像形成要素（６Ｃ）、（６Ｍ）、（６Ｙ）及び（６Ｋ）において、感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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）及び（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）及び（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）及び（４Ｋ）により潜像を現像してトナー像が形成される。現像部材（４Ｃ）、（４Ｍ）、（４Ｙ）及び（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なう現像部材で、４つの感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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。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）及び（１Ｋ）との当接位置（転写部）で各色トナー像の転写が行なわれる。感光体上のトナー像は、転写ブラシ（１１Ｃ）、（１１Ｍ）、（１１Ｙ）及び（１１Ｋ）に印加された転写バイアスと感光体（１Ｃ）、（１Ｍ）、（１Ｙ）及び（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。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）及び（１Ｋ）上に残った残留トナーは、クリーニング装置（５Ｃ）、（５Ｍ）、（５Ｙ）及び（５Ｋ）で回収される。なお、図１０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なく、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１０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。
【０１０３】
以上に示した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、除電手段等を含んだ１つの装置（部品）である。
【０１０４】
【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。
（実施例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なった。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。
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、ろ過した。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。
この水ペーストにテトラヒドロフラン１５００部を加え、室温下でホモミキサー（ケニス、ＭＡＲＫ，ｆモデル）により強烈に撹拌（２０００ｒｐｍ）し、ペーストの濃紺色の色が淡い青色に変化したら（撹拌開始後２０分）、撹拌を停止し、直ちに減圧濾過を行なった。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。
【０１０５】
（実施例２）
実施例１における結晶変換溶媒をテトラヒドロフランからトルエンに変更した以外は、実施例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。これを顔料２とする。
【０１０６】
（実施例３）
実施例１における結晶変換溶媒をテトラヒドロフランから塩化メチレンに変更した以外は、実施例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。これを顔料３とする。
【０１０７】
（比較例１）
実施例１における結晶変換溶媒をテトラヒドロフランから２−ブタノンに変更した以外は、実施例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。これを顔料４とする。
【０１０８】
（比較例２）
実施例１におけるテトラヒドロフランによる結晶変換処理に際して、特開２００１−１９８７１号公報に記載の合成例１の方法に準じて、結晶変換時間を４時間に設定した以外は実施例１と同様に処理し、チタニルフタロシアニン結晶を得た。これを顔料５とする。
【０１０９】
（比較例３）
実施例１において、テトラヒドロフランによる結晶変換処理に際して、特開２００１−１９８７１号公報に記載の合成例１の方法に準じて、結晶変換時間を４時間に設定し、更に一昼夜静置保管して、翌日濾過を行なった以外は、実施例１と同様に処理し、チタニルフタロシアニン結晶を得た。これを顔料６とする。
【０１１０】
実施例１で作製された水ペーストの一部をイオン交換水でおよそ１重量％になるように希釈し、表面を導電性処理した銅製のネットですくい取り、チタニルフタロシアニンの粒子サイズを透過型電子顕微鏡（ＴＥＭ、日立：Ｈ−９０００ＮＡＲ）にて、７５０００倍の倍率で観察を行なった。平均粒子サイズとして、以下のように求めた。
上述のように観察されたＴＥＭ像をＴＥＭ写真として撮影し、映し出されたチタニルフタロシアニン粒子（針状に近い形）を３０個任意に選び出し、それぞれの長径の大きさを測定する。測定した３０個体の長径の算術平均を求めて、平均粒子サイズとした。
以上の方法により求められた実施例１における水ペースト中の平均粒子サイズは、０．０６μｍであった。
【０１１１】
実施例１〜３、比較例１〜３における濾過直前の結晶変換後チタニルフタロシアニン結晶を、上記の水ペーストと同じ方法によりＴＥＭ観察を行なった。それぞれ、所定の結晶変換処理を行ない、濾過直前の液をサンプリングし、それぞれの結晶変換溶媒でおよそ１重量％になるように希釈し、測定に供した。求めた平均粒子サイズを表１に示す。なお、実施例１〜３、比較例１〜３で作製されたチタニルフタロシアニン結晶は、水ペーストとは異なり結晶の形が同一ではなかった（三角形に近い形、四角形に近い形など）。このため、結晶の最も大きな対角線の長さを長径として、計算を行なった。
【０１１２】
【表１】

【０１１３】
実施例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。
上述のように得られた水ペーストの乾燥粉末と、実施例１〜４および比較例１〜２で得られたチタニルフタロシアニン結晶についての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
【０１１４】
水ペーストの乾燥粉末のＸ線回折スペクトルを図１１に示す。
また、実施例１〜３および比較例２〜３で得られたチタニルフタロシアニン結晶については、いずれの場合にも同様のＸ線回折スペクトルを示したため、代表例として実施例１で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを図１２に示す。比較例１で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルは、実施例１〜３および比較例２〜３で得られたチタニルフタロシアニン結晶と異なるＸ線回折スペクトルであった（最低角が７．５°に存在する）。これを図１３に示す。
【０１１５】
（比較例４）
特開平１−２９９８７４号公報に記載の方法に準じて顔料を作製した。すなわち、実施例１で作製したウェットケーキ（水ペースト）を乾燥し、乾燥物１ｇをポリエチレングリコール５０ｇに加え、１００ｇのガラスビーズと共に、サンドミルを１時間行なった。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７とする。
【０１１６】
（比較例５）
特開平３−２６９０６４号公報に記載の方法に準じて顔料を作製した。すなわち、実施例１で作製したウェットケーキを乾燥し、乾燥物１ｇをイオン交換水１０ｇとモノクロルベンゼン１ｇ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８とする。
【０１１７】
（比較例６）
特開平２−８２５６号公報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９．８ｇと１−クロロナフタレン７５ｍｌを撹拌混合し、窒素気流下で四塩化チタン２．２ｍｌ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、ついで１−クロロナフタレンで粉体が青色になるまで洗浄、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、乾燥し顔料を得た。これを顔料９とする。
【０１１８】
（比較例７）
特開昭６４−１７０６６号公報に記載の方法に準じて顔料を作製した。すなわち、α型ＴｉＯＰｃ５部を食塩１０ｇおよびアセトフェノン５ｇと共にサンドグラインダーにて１００℃−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１０とする。
【０１１９】
（比較例８）
特開平１１−５９１９号公報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２０．４部、四塩化チタン部７．６部をキノリン５０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２１．３部を得た。このチタニルフタロシアニン２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４００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（含有フタロシアニン量２部と仮定して）をＴＨＦ１００部中で約５時間攪拌を行ない、ろ過、洗浄を行ない、乾燥して顔料を得た。これを顔料１１とする。
【０１２０】
以上の比較例４〜８で作製した顔料は、先ほどと同様の方法で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２に先の表１と同様な評価結果を示す。
【０１２１】
【表２】

【０１２２】
（実施例４）
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）。
実施例１で作製したチタニルフタロシアニン結晶（顔料１）　　　１５部
ポリビニルブチラール（積水化学製：ＢＸ−１）　　　　　　　　１０部
２−ブタノン　　　　　　　　　　　　　　　　　　　　　　　２８０部
市販のビーズミル分散機に直径０．５ｍｍのＰＳＺ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１５００ｒ．ｐ．ｍ．にて分散を行ない、体積平均粒径が０．２μｍより小さくなったところで分散を停止した。
【０１２３】
（実施例５）
実施例４におけるチタニルフタロシアニン結晶を、顔料２に変更した以外は、実施例４と同様に分散液を作製した（これを分散液２とする）。
【０１２４】
（実施例６）
実施例４におけるチタニルフタロシアニン結晶を、顔料３に変更した以外は、実施例４と同様に分散液を作製した（これを分散液３とする）。
【０１２５】
（実施例７）
実施例４におけるチタニルフタロシアニン結晶を、顔料４に変更した以外は、実施例４と同様に分散液を作製した（これを分散液４とする）。
【０１２６】
（比較例９）
実施例４におけるチタニルフタロシアニン結晶を、顔料５に変更した以外は、実施例４と同様に分散液を作製した（これを分散液５とする）。
【０１２７】
（比較例１０）
実施例４におけるチタニルフタロシアニン結晶を、顔料６に変更した以外は、実施例４と同様に分散液を作製した（これを分散液６とする）。
【０１２８】
（比較例１１）
実施例４におけるチタニルフタロシアニン結晶を、顔料７に変更した以外は、実施例４と同様に分散液を作製した（これを分散液７とする）。
【０１２９】
（比較例１２）
実施例４におけるチタニルフタロシアニン結晶を、顔料８に変更した以外は、実施例４と同様に分散液を作製した（これを分散液８とする）。
【０１３０】
（比較例１３）
実施例４におけるチタニルフタロシアニン結晶を、顔料９に変更した以外は、実施例４と同様に分散液を作製した（これを分散液９とする）。
【０１３１】
（比較例１４）
実施例４におけるチタニルフタロシアニン結晶を、顔料１０に変更した以外は、実施例４と同様に分散液を作製した（これを分散液１０とする）。
【０１３２】
（比較例１５）
実施例４におけるチタニルフタロシアニン結晶を、顔料１１に変更した以外は、実施例４と同様に分散液を作製した（これを分散液１１とする）。
【０１３３】
（比較例１６）
比較例１０において、分散時間を変更し、結晶型の変化が起こらない時間まで分散を行ない、分散を停止した（これを分散液１２とする）。
【０１３４】
実施例４〜７および比較例９〜１６で作製された分散液中の顔料粒子サイズ（体積平均粒径）を堀場製作所：ＣＡＰＡ７００にて測定した。また、作製された分散液を乾固し、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。結果を合わせて表３に示す。
【０１３５】
【表３】

図１４中の矢印（２６．３゜）のピークが新たに出現した。結晶の一部が他の結晶型へ変化している。
【０１３６】
（実施例８）
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、２５μｍの電荷輸送層を形成し、積層感光体を作製した。

【０１３７】
【化１３】

塩化メチレン　　　　　　　　　　　　　　　　　　　　　　　　８０部
【０１３８】
（実施例９）
実施例８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、実施例８と同様に感光体を作製した。
【０１３９】
（実施例１０）
実施例８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、実施例８と同様に感光体を作製した。
【０１４０】
（実施例１１）
実施例８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、実施例８と同様に感光体を作製した。
【０１４１】
（比較例１７）
実施例８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、実施例８と同様に感光体を作製した。
【０１４２】
（比較例１８）
実施例８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、実施例８と同様に感光体を作製した。
【０１４３】
（比較例１９）
実施例８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、実施例８と同様に感光体を作製した。
【０１４４】
（比較例２０）
実施例８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、実施例８と同様に感光体を作製した。
【０１４５】
（比較例２１）
実施例８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、実施例８と同様に感光体を作製した。
【０１４６】
（比較例２２）
実施例８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、実施例８と同様に感光体を作製した。
【０１４７】
（比較例２３）
実施例８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、実施例８と同様に感光体を作製した。
【０１４８】
（比較例２４）
実施例８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、実施例８と同様に感光体を作製した。
【０１４９】
以上のように作製した実施例８〜１１および比較例１７〜２４の電子写真感光体を図６に示す電子写真装置に搭載し、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、帯電部材として接触方式の帯電ローラーを用い、下記の帯電条件で画像を出力した。
帯電条件：
ＤＣバイアス：約−１６００Ｖ（感光体表面の未露光部電位が−９００Ｖになるように設定）
書き込み率６％のチャートを用い、連続して２００００枚の印刷を行ない、初期及び２００００枚後の画像を評価した。画像評価は、初期及び２００００枚後に白ベタ画像を出力し、地肌汚れの評価を行なった（下記ランクで評価した）。
また、同時に、現像部位置における感光体の表面電位（黒ベタ画像部）を測定するために、現像器が装着される位置に電位計がセットできるような治具を用いて、初期及び２００００枚の画像出力後の感光体表面電位を測定した。結果を表４に示す。
【０１５０】
【表４】

地汚れランク：
５：地汚れほとんどなし、
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
【０１５１】
（実施例１２）
実施例８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、実施例８と同様に感光体を作製した。
◎電荷輸送層塗工液
下記組成の高分子電荷輸送物質　　　　　　　　　　　　　　　　１０部
（重量平均分子量：約１４００００）
【０１５２】
【化１４】

下記構造の添加剤　　　　　　　　　　　　　　　　　　　　　０．５部
【０１５３】
【化１５】

塩化メチレン　　　　　　　　　　　　　　　　　　　　　　１００部
【０１５４】
（実施例１３）
実施例８における電荷輸送層の膜厚を２２μｍ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、３μｍの保護層を設けた以外は実施例８と同様に感光体を作製した。
◎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
【０１５５】
【化１６】

α―アルミナ微粒子　　　　　　　　　　　　　　　　　　　　　　４部
（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　　５００部
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　１５０部
【０１５６】
（実施例１４）
実施例８における電荷輸送層の膜厚を２２μｍ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、３μｍの保護層を設けた以外は実施例８と同様に感光体を作製した。
◎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
【０１５７】
【化１７】

酸化チタン微粒子　　　　　　　　　　　　　　　　　　　　　　　　４部
（比抵抗：１．５×１０^１０Ω・ｃｍ、平均一次粒径：０．５μｍ）
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　　　５００部
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　　１５０部
【０１５８】
（実施例１５）
実施例８における電荷輸送層の膜厚を２２μｍ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、３μｍの保護層を設けた以外は実施例８と同様に感光体を作製した。
◎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
【０１５９】
【化１８】

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）
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　　　５００部
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　　１５０部
【０１６０】
（実施例１６）
実施例８における電荷輸送層の膜厚を２２μｍ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、３μｍの保護層を設けた以外は実施例８と同様に感光体を作製した。
◎保護層塗工液
下記構造式の高分子電荷輸送物質　　　　　　　　　　　　　　　１７部
（重量平均分子量：約１４００００）
【０１６１】
【化１９】

アルミナ微粒子　　　　　　　　　　　　　　　　　　　　　　　　４部
（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　　５００部
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　１５０部
【０１６２】
以上のように作製した実施例１２〜１６の電子写真感光体を、実施例８の感光体と共に、図６に示す電子写真装置に搭載し、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、帯電部材として接触方式の帯電ローラーを用い、下記の帯電条件で画像を出力した。
帯電条件：
ＤＣバイアス：−１６００Ｖ（感光体表面の未露光部電位が−９００Ｖになるように設定）
書き込み率６％のチャートを用い、連続して５００００枚の印刷を行ない、初期及び５００００枚後の画像を評価した。画像評価は、初期及び５００００枚後に白ベタ画像を出力し、地肌汚れの評価を行なった（下記ランクで評価した）。
また、５００００枚出力後、３０℃−９０％ＲＨの環境下で画像を５０枚出力した。
更に、５００００枚出力における感光体表面の摩耗量を測定した。以上の結果を表５に示す。
【０１６３】
【表５】

地汚れランク：
５：地汚れほとんどなし、
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
【０１６４】
（実施例１７）
実施例８で作製した感光体を用い、図６に示す電子写真装置に搭載し、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、帯電部材として図７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：−１６５０Ｖ（感光体表面の未露光部電位が−９００Ｖになるように設定）
書き込み率６％のチャートを用い、連続して２００００枚の印刷を行ない、初期及び２００００枚後の画像を評価した。２００００枚後にハーフトーン画像を出力して評価を行なった。
【０１６５】
（実施例１８）
実施例１７で実施した評価を、以下のように帯電条件を変更して行なった。
帯電条件：
ＤＣバイアス：−９００Ｖ
ＡＣバイアス：２．０ｋＶ（ｐｅａｋ　ｔｏ　ｐｅａｋ）、周波数：１．５ｋＨｚ
【０１６６】
（実施例１９）
実施例１８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１８と同様に評価を行なった。
【０１６７】
（実施例２０）
実施例１８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１８と同様に評価を行なった。
以上の結果を実施例８の場合と合わせて表６に示す。
【０１６８】
【表６】

【０１６９】
（実施例２１）
実施例８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）に変更した以外は実施例８と同様に感光体を作製した。
【０１７０】
（実施例２２）
実施例２１において、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、実施例１７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。
◎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℃、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℃）にて封孔処理を行なった。その後純水による洗浄を経て、６μｍの陽極酸化皮膜が形成された支持体を得た。
【０１７１】
（比較例２５）
比較例１７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）に変更した以外は比較例１７と同様に感光体を作製した。
【０１７２】
（比較例２６）
比較例２４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）に変更した以外は比較例２４と同様に感光体を作製した。
【０１７３】
以上のように作製した実施例２１〜２２および比較例２５〜２６の感光体を、図９に示すような電子写真装置用カートリッジに装着し、図１０に示す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、帯電部材として図７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：１．８ｋＶ（ｐｅａｋ　ｔｏ　ｐｅａｋ）、周波数：１．５ｋＨｚ
書き込み率６％のフルカラーチャートを用い、連続して２００００枚の印刷を行ない、初期及び２００００枚後の画像を評価した。画像評価は、初期及び２００００枚後に白ベタ画像を出力し、地肌汚れの評価を行なった。また、色再現性を評価するチャートにて、２００００枚後の色再現性を評価した。結果を表７に示す。
【０１７４】
【表７】

地汚れランク：
５：地汚れほとんどなし、
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
【０１７５】
最後に、本発明のチタニルフタロシアニン結晶の特徴であるブラッグ角２θ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。
【０１７６】
（測定例１）
実施例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、先ほどと同様に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１５に示す。
【０１７７】
（測定例２）
比較例１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、先ほどと同様に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１６に示す。
【０１７８】
図１５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分かる。一方、図１６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１５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。
【０１７９】
【発明の効果】
以上、詳細且つ具体的な説明より明らかなように、本発明によれば、一次粒子の極めて小さなチタニルフタロシアニン結晶およびその製造方法が提供される。また、前記チタニルフタロシアニン顔料を用いて分散液を作製する際に、結晶安定性が高く、粒子サイズの小さな分散液を得ることのできるチタニルフタロシアニン結晶およびその製造方法が提供される。
上記のチタニルフタロシアニン結晶を用いることにより、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が提供される。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。
更に上記感光体を使用することにより、高速プリントが可能で、異常画像の発生の少ない、安定な電子写真方法、電子写真装置および電子写真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】本発明の好ましい不定形チタニルフタロシアニンの粒子状態を表わす電子顕微鏡写真である。
【図２】本発明の結晶変換後のチタニルフタロシアニンの電子顕微鏡写真である。
【図３】本発明の結晶変換後のチタニルフタロシアニンの他の電子顕微鏡写真である。
【図４】本発明に用いられる電子写真感光体の構成例を示す断面図である。
【図５】本発明に用いられる電子写真感光体の他の構成例を示す断面図である。
【図６】本発明の電子写真プロセス及び電子写真装置を説明するための概略図である。
【図７】近接帯電機構を示す概略図（ギャップ保持機構が帯電部材側に形成されている）である。
【図８】本発明の電子写真プロセスの他の例を示す概略図である。
【図９】本発明の電子写真プロセスカートリッジの一例を示す概略図である。
【図１０】本発明のタンデム式フルカラー電子写真装置を説明するための他の概略図である。
【図１１】水ペーストの乾燥粉末のＸ線回折スペクトルを示す図である。
【図１２】実施例１で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを示す図である。
【図１３】比較例１で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを示す図である。
【図１４】比較例９で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを示す図である。
【図１５】測定例１で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを示す図である。
【図１６】測定例２で得られたチタニルフタロシアニン結晶のＸ線回折スペクトルを示す図である。
【符号の説明】
１Ｃ、１Ｍ、１Ｙ、１Ｋ　ドラム状感光体
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
７　転写紙
８　給紙コロ
９　レジストローラ
１０　転写搬送ベルト
１１Ｃ、１１Ｍ、１１Ｙ、１１Ｋ　転写ブラシ
１２　定着装置
２１　感光体
２２　除電ランプ
２３　帯電部材
２５　画像露光部
２６　現像ユニット
２７　転写前チャージャ
２８　レジストローラ
２９　転写紙
３０　転写チャージャ
３１　分離チャージャ
３２　分離爪
３３　クリーニング前チャージャ
３４　ファーブラシ
３５　ブレード
４１　導電性支持体
４５　電荷発生層
４７　電荷輸送層
４９　保護層
５０　感光体
５１　帯電ローラー
５２　ギャップ形成部材
５３　金属シャフト
５４　画像形成領域
５５　非画像形成領域
６１　感光体
６２ａ　駆動ローラ
６２ｂ　駆動ローラ
６３　帯電チャージャ
６４　像露光源
６５　転写チャージャ
６６　クリーニング前露光
６７　クリーニングブラシ
６８　除電光源
７６　感光体
７７　帯電チャージャ
７８　クリーニングブラシ
７９　画像露光部
８０　現像ローラ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a titanyl phthalocyanine crystal, a method for producing a titanyl phthalocyanine crystal, an electrophotographic photosensitive member manufactured using the same, an electrophotographic method using the electrophotographic photosensitive member, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus. About. Specifically, titanyl phthalocyanine crystal having excellent dispersibility and crystal stability and good handling properties, a simple and stable method for producing the above-mentioned titanyl phthalocyanine crystal, and stability of the charging potential and residual potential of the photoreceptor by repeated use. TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor having excellent image quality and less occurrence of abnormal images such as background stain, an electrophotographic method using the same, an electrophotographic apparatus, and a process cartridge for the electrophotographic 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.
In forming such a film containing an organic pigment, a wet film forming method, which can easily increase the area, occupies most of the film. 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 is determined by the dispersibility of the pigment. Thus, a good dispersion is one in which the pigment is sufficiently dispersed in the vehicle and the state of dispersion is maintained for a long time.
[0003]
In recent years, digital electrophotographic systems are mainly used, and particularly, negative / positive development (reversal development) is mainly used. In the case of negative-positive development, the potential of a portion where optical writing is performed on a photosensitive member used in an electrophotographic system is attenuated, so that toner is developed in this portion to form an image. This is performed in consideration of the life of the light source and the light fatigue of the photoconductor since the writing rate of the original is at most about 10%. However, the background portion of the output document corresponds to the unexposed portion (high potential portion) of the photoreceptor, and when the photosensitive layer (especially the charge generation layer) has a coating film defect or the like, the potential is originally maintained. The potential background portion (white background) attenuates the potential, and as a result, a point defect (background stain, black spot, etc.) not present in the background portion of the input document may occur. This defect may be mistaken for a point in a drawing, a period, a comma, etc. in an English manuscript, and can be said to be a fatal defect as an image. Such point defects are often derived from a layer composed of a dispersion film of a pigment or the like. Therefore, in order to reduce such point defects, it is necessary to prepare a dispersion having good dispersibility such as a pigment. At this time, the pigment particle size in the dispersion is preferably as small as possible. However, if the primary particle size is approximately 0.2 μm or less, the point defects as described above are considerably reduced.
[0004]
In order to prepare such a dispersion, various dispersers and dispersion systems have been proposed so far, and methods for increasing the dispersion efficiency have been devised. For example, Patent Documents 1 to 14 are mentioned, all of which use various dispersing devices, dispersing conditions, or by improving, using pigment particles having a large average size synthesized, in a dispersion liquid to be produced. This is a technique for making pigment particles as fine as possible (reducing the particle size). Such a dispersion technique can be said to be an excellent technique in terms of how efficiently the pigment used in preparing the dispersion is dispersed to the primary particle size. However, it is extremely difficult to make the state smaller than the primary particle size, and it is no exaggeration to say that the limit of the particle size in the dispersion is basically determined by the primary particle size of the pigment used. Some of these include those that pulverize the primary particles themselves by applying a huge amount of energy, but these break the crystals themselves, which causes the following disadvantages (for example, a decrease in dispersion efficiency, Crystal type transition).
[0005]
On the other hand, titanyl phthalocyanine is known as a useful charge generating substance for an electrophotographic photosensitive member. This titanyl phthalocyanine is a polymorphic pigment having many crystal forms as an aggregate even if represented by the same structural formula. In particular, a 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 has a polymorphic crystal form. Among them, it specifically exhibits extremely high photocarrier generation efficiency as a charge generation material for an electrophotographic photosensitive member. However, since it is a metastable state as a crystalline state, it easily transitions to another crystal type. When excessive energy is given 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. Since this crystal has a much lower carrier generation efficiency than the previous crystal, even if only a part of the crystal is displaced, using it as a charge generation material of the photoreceptor will lower the photosensitivity and increase the residual potential when used repeatedly. A problem arises.
[0006]
On the other hand, if the dispersion conditions are made mild to prevent this crystal transition, a dispersion having a large average particle size is produced as described above, or a dispersion having coarse particles remaining is produced. When such a dispersion having a large average particle size is used, the surface area of the charge generating substance particles becomes small, making it difficult to transfer charges to and from the charge transporting substance. This causes a problem such as an increase in the residual potential. If the coarse particles remain, problems such as background stain and black spots in negative-positive development occur.
As described above, in the dispersion of the titanyl phthalocyanine pigment particles, there is a trade-off relationship between the stability of the crystal form and the miniaturization of the particles, and there is no means for simply solving this.
[0007]
Another approach for reducing the particle size of the pigment in the dispersion is to use a pigment that is easily dispersed, that is, a pigment having an extremely small primary particle. According to this method, small primary particles of a pigment to be used are synthesized in advance, and a dispersion liquid having a small particle size is obtained without giving excessive energy at the time of dispersion. This method is considered to be an extremely effective method when not only improving the dispersion efficiency but also when using a pigment which is liable to crystal transition as represented by the above-mentioned titanyl phthalocyanine.
[0008]
However, few approaches from the point of view of pigment synthesis have been found so far. In this regard, only a technique similar to Patent Document 15 is disclosed. Patent Literature 15 discloses a method of preparing a dispersion using a means that uses a dispersing means simultaneously with the crystal conversion. Certainly, with this method, a dispersion of the primary particle size of the pigment formed by the crystal transformation can be formed, but in consideration of the fact that the dispersion is subsequently used as a coating liquid, the crystal transformation solvent is used. However, it is not always the most suitable as a coating solvent, and has a drawback that it has limitations in coating. In addition, since it cannot be stored as pigment powder, restrictions on storage are also imposed.
From the above, without crystal transition of titanyl phthalocyanine crystal which is extremely useful as a charge generating substance of an electrophotographic photoreceptor, in order to prepare a dispersion having a small average particle size, a titanyl phthalocyanine crystal having a small primary particle size and its The development of a manufacturing method was eagerly desired.
[0009]
[Patent Document 1]
JP-A-4-337362
[Patent Document 2]
JP-A-5-188614
[Patent Document 3]
JP-A-7-289870
[Patent Document 4]
JP-A-8-44086
[Patent Document 5]
JP-A-8-123045
[Patent Document 6]
JP-A-8-272111
[Patent Document 7]
JP-A-9-212873
[Patent Document 8]
JP-A-11-30871
[Patent Document 9]
JP-A-11-258827
[Patent Document 10]
JP-A-2000-1226638
[Patent Document 11]
JP 2000-181104 A
[Patent Document 12]
JP-A-2000-281931
[Patent Document 13]
JP 2001-265027 A
[Patent Document 14]
JP 2001-290292 A
[Patent Document 15]
JP 2000-239556 A
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide a titanyl phthalocyanine crystal having extremely small primary particles and a method for producing the same. Another object of the present invention is to provide a titanyl phthalocyanine crystal having high crystal stability and capable of obtaining a dispersion having a small particle size when producing a dispersion using the titanyl phthalocyanine pigment, and a method for producing the same.
Another object of the present invention is to provide a stable electrophotographic photoreceptor which does not cause a decrease in chargeability and an increase 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 a stable electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus, which can perform high-speed printing and generate less abnormal images.
[0011]
[Means for Solving the Problems]
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, the probability of deactivation of the photocarriers inside the particles increases before the photocarriers generated by the charge generation material are transferred to the charge transport material. . In addition, when the pigment particles are large, the surface area is inevitably reduced, and the contact amount between the charge generating material and the charge transporting material is reduced. As a result, the carrier injection efficiency decreases when the photocarrier is transferred to the charge transporting material. Further, when the charge generation substance particles are large, the probability of a coating film defect in the photosensitive layer (charge generation layer) increases, which causes a problem that image defects easily occur.
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.
In order to reduce the particle size of the charge generating material in the dispersion for coating the photosensitive layer in this way, various dispersion methods have been proposed, but each of the secondary particles has an aggregate structure of the charge generating material. A major issue is how to pulverize and disperse this into primary particles. In these methods, the dispersion energy is enlarged, 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 generating material, It is difficult to make the particles smaller than the primary particle size by a usual method.
[0012]
On the other hand, there has been proposed a dispersion method capable of giving a higher 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.
[0013]
However, in the case of an organic charge generation substance, 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 where a material that exhibits a specific function is changed to a material that does not sufficiently exhibit the function even if the material is intended to be used.
[0014]
The phthalocyanine crystal used in the present invention, particularly the titanyl phthalocyanine crystal, is a polymorphic material. The crystal type having a particularly high photocarrier generation efficiency has a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα. Only crystals having a maximum diffraction peak at least at 27.2 ° as a diffraction peak (± 0.2 °), and other crystal-type materials also have a function as a charge generating material, but are presently used in electrophotographic processes. However, it does not have the characteristics satisfying the high speed, the small diameter of the photoreceptor, and the high stability at the time of repeated use. Therefore, it can be said that the crystal type is a specific crystal type.
[0015]
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 transferred to 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.
[0016]
In order to solve the above-mentioned problems, the present inventors have tried to analyze the pulverization / dispersion process of titanyl phthalocyanine crystals, and have obtained the following knowledge.
That is, in the step of dispersing the titanyl phthalocyanine crystal, when dispersing to the target particle size, excessive dispersion energy must be given due to the presence of primary particles larger than the target particle size. In addition, there is a remarkable difference between the energy required to disperse the secondary particles, which are aggregates of the primary particles, down to the primary particles, and the energy required to further pulverize the huge primary particles. In the former, the force acting on the crystal is given to the dispersion itself, and does not lead to the crystal transition. In the latter case, the applied energy acts on the pulverization and, at the same time, the crystal transition proceeds.
From the above, the present inventors, by making the primary particles of titanyl phthalocyanine crystals subjected to dispersion as fine as possible, without giving excessive dispersion energy, fine particle size, and crystal stability It has been found that a dispersion having a high water content can be produced.
[0017]
The average particle size of the primary particles of the titanyl phthalocyanine crystal in the present invention is defined as follows.
The liquid containing the crystal-converted titanyl phthalocyanine crystal was observed with a transmission electron microscope (TEM), the obtained TEM image was taken as a TEM photograph, and 30 projected titanyl phthalocyanine crystals were arbitrarily selected. Measure the length of the major axis. The arithmetic average of the longer diameters of the 30 individuals measured is determined and defined as the average particle size.
[0018]
Next, the present inventors attempted an approach from the synthesis of a titanyl phthalocyanine crystal, and obtained the following knowledge.
That is, a titanyl phthalocyanine crystal having a maximum diffraction peak of at least 27.2 ° is generally synthesized from titanyl phthalocyanine having lower crystal stability. As a commonly used technique, a crude crude product (crude) synthesized according to a conventional method is converted into an amorphous titanyl phthalocyanine (or low-crystallinity) which is considered to have the lowest crystal stability by a method called acid paste treatment with sulfuric acid or the like. To titanyl phthalocyanine). This is subjected to crystal conversion by various methods to obtain a titanyl phthalocyanine crystal having a desired crystal form. In this crystal transformation, the method most frequently used is a method in which crystal transition is carried out together with a suitable organic solvent in the presence of water.
[0019]
The present inventors have paid attention to the morphology of titanyl phthalocyanine crystal particles before and after the crystal transformation. The particle size of the amorphous titanyl phthalocyanine (or low crystalline titanyl phthalocyanine) after the above-mentioned acid paste treatment is the one obtained by precipitating from the acid solution state of titanyl phthalocyanine in water having low solubility, and the primary particle size is It is small. Although it depends on the conditions of the acid paste treatment, fine particles (a shape close to needles) of about 0.1 μm or less are usually formed (see FIG. 1). Subsequently, the titanyl phthalocyanine crystal that has been subjected to the crystal conversion treatment is a crystal that grows at the same time as the crystal transition, and usually, after the crystal conversion is performed more reliably, the crystal is separated and filtered out. The primary particles are quite large (about 0.3 to 0.4 μm, and about 1 μm for large ones) (see FIG. 2). From the above, it was found that the primary particle size of the titanyl phthalocyanine crystal used in the present invention was determined by this crystal conversion step.
[0020]
In the present invention, a diffraction peak (± 0.2 °) of Bragg angle 2θ with respect to characteristic X-ray (wavelength: 1.542 °) of CuKα, which is a particularly preferred crystal form, is at least 27.2 °. 7. It has a diffraction peak, further has a major peak at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, and A titanyl phthalocyanine crystal having no peak between the 3 ° peak and the 9.4 ° peak and further having no peak at 26.3 ° is disclosed in JP-A-2001-19871. However, when a titanyl phthalocyanine crystal is prepared under the conditions disclosed in this publication, a crystal having large primary particles is obtained as described above, and has the above-described problems.
[0021]
Thus, the method of eliminating the relationship between the fineness of the particles and the trade-off of crystal stability in the dispersion of the titanyl phthalocyanine crystal, which has been an issue so far, is how small the primary particles of the titanyl phthalocyanine crystal to be used are synthesized. That would be.
As a result of an examination in view of this point, when the amorphous particles of amorphous titanyl phthalocyanine (or low crystallinity titanyl phthalocyanine), which are fine particles, are used as a raw material and the crystal conversion is carried out with an organic solvent in the presence of water, the crystallinity becomes The conversion time is set short (generally less than 1 hour, preferably less than 30 minutes, depending on the crystal conversion conditions), and the organic solvent is used before crystal growth occurs (before the primary particle size grows to 0.2 μm or more). It was found that finer primary particles could be obtained by further separating and filtering and extracting desired crystals (see FIG. 3).
[0022]
However, the above-mentioned problem is solved by the present invention (1) that a maximum diffraction peak at least 27.2 ° is obtained as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to characteristic X-ray (wavelength 1.542 °) of CuKα. Further, it has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the diffraction peak on the lowest angle side, and has a peak at 7.3 °. A titanyl phthalocyanine crystal having no peak between the peak and the peak at 9.4 ° and having an average primary particle size of 0.2 μm or less ”; (2)“ the titanyl phthalocyanine further comprises: The titanyl phthalocyanine crystal according to the above (1), which has no peak at 26.3 ° ”.
[0023]
In addition, the above-mentioned problem is solved by (3) the present invention, in which the diffraction peak (± 0.2 °) of the Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα is at least 7.0 to 7.5 °. Amorphous titanyl phthalocyanine or low-crystalline titanyl phthalocyanine having an average primary particle size of 0.1 μm or less having a maximum diffraction peak and a half width of the diffraction peak of 1 ° or more is crystallized with an organic solvent in the presence of water. The method according to item (1) or, wherein, after the conversion, the titanyl phthalocyanine after the crystal conversion is separated from the organic solvent and filtered before the average size of the primary particles after the crystal conversion grows to 0.2 μm or more. (4) The method for producing a titanyl phthalocyanine crystal according to (2), (4) wherein the organic solvent is at least tetrahydrofuran, toluene, methylene chloride, and carbon disulfide. (3) The method for producing a titanyl phthalocyanine crystal according to the above (3), which comprises one selected from hydrogen, orthodichlorobenzene and 1,1,2-trichloroethane.
[0024]
Further, the present invention provides (5) an electrophotographic photosensitive member according to the present invention, wherein at least a charge generation layer and a charge transport layer are laminated on a conductive support, wherein the charge generation layer is provided with the (1) Or an electrophotographic photoreceptor comprising the titanyl phthalocyanine crystal according to item (2) or (2), wherein the charge transport layer contains a polymer charge transport material. (7) The electrophotographic photoreceptor according to the above (5), (7) wherein the protective layer is laminated on the charge transport layer (5) or (6). (8) "The protective layer has a specific resistance of 10 ¹⁰ (9) The electrophotographic photoreceptor according to the above (7), which contains an inorganic pigment or a metal oxide of Ω · cm or more. ¹⁰ (8) The electrophotographic photoreceptor according to the above (8), wherein the metal oxide has a specific resistance of 10 or more. ¹⁰ (9) The electrophotographic photoreceptor according to the above (9), wherein the protective layer contains a polymer charge transport material. (8) The electrophotographic photosensitive member according to any one of the above items (8) to (10) ", (12) that the electroconductive photosensitive member has an electroconductive support having a surface treated with an anodized film. The electrophotographic photoreceptor according to any one of the above items (5) to (11) ".
[0025]
The object of the present invention is also directed to (13) an image forming method of the present invention, wherein at least charging, image exposure, development, and transfer are repeatedly performed on the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the item (5). To (12), wherein the image forming method is an electrophotographic photosensitive member according to any one of (1) to (12).
[0026]
The above object is also achieved by (14) an image forming apparatus including an image forming element including at least a charging unit, an image exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member. An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of the above items (5) to (12); (16) The image forming apparatus according to the above (14), wherein a plurality of the charging members are arranged such that a charging member is in contact with or close to a photosensitive member. (17) The image forming apparatus according to (14) or (15), wherein the gap between the charging member and the photoconductor is 200 μm or less. Image forming apparatus ", (18)" the charging Stage by superimposing an AC component on a DC component, is solved by the second (16) section or a (17) The image forming apparatus according to claim ', characterized in that it is what gives the charged photoreceptor.
[0027]
Further, an object of the present invention is to provide (19) a process cartridge for an image forming apparatus including at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is any of the above items (5) to (12). The process cartridge for an image forming apparatus, wherein the process cartridge is an electrophotographic photosensitive member according to any one of the above items.
[0028]
The specific method is described below.
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.
For example, as a first method, a method of heating a mixture of phthalic anhydride, a metal or a metal halide and urea in the presence or absence of a high-boiling solvent is used. In this case, a catalyst such as ammonium molybdate is used as needed. The 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. A third method is to first react ammonia with phthalic anhydride or phthalonitriles to produce an intermediate such as 1,3-diiminoisoindoline, and then react with a metal halide in a high boiling solvent. It is a way to make it. The 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.
[0029]
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.
As a specific method, the above synthesized 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% by weight. The product thus prepared is amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used in the present invention. At this time, this 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 1.542 °). 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. Furthermore, it is important that the average particle size of the primary particles is 0.1 μm or less for the subsequent crystal transformation.
[0030]
FIG. 1 shows an electron micrograph showing a preferred amorphous titanyl phthalocyanine particle state. For observation of the particle state, a transmission electron microscope (TEM; Hitachi, H-9000NAR) was used. The above-mentioned aqueous paste of titanyl phthalocyanine was diluted with ion-exchanged water so that the pigment concentration was about 1% by weight, scooped on a conductive net, dried as it was, and observed. The scale bar in the figure is 0.2 μm.
[0031]
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 between the 7.3 ° peak and the 9.4 ° peak is preferably used, and a titanyl phthalocyanine crystal having no peak at 26.3 ° is particularly preferably used. . As a specific method, the amorphous form of 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, the point of the present invention is to control the major axis of the primary particles of the titanyl phthalocyanine crystal after the crystal conversion to 0.2 μm or less.
[0032]
At this time, as the organic solvent used, any organic solvent can be used as long as a desired crystal form can be obtained, and 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. According to observations by the present inventors in the operation of crystal transformation, the above-mentioned amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) has a primary particle size of 0.1 μm or less (mostly 0.01 to 0). However, in the case of crystal conversion, it was found that the crystal was converted along with the crystal growth. Usually, in this type of crystal conversion, a sufficient crystal conversion time is secured due to fear of remaining raw materials, and after the crystal conversion is performed sufficiently, filtration is performed, and titanyl phthalocyanine crystal having a desired crystal form is obtained. Is what you get. For this reason, despite the fact that a raw material having sufficiently small primary particles is used as the raw material, a crystal having a large primary particle (generally 0.3 to 0.5 μm) is obtained as a crystal after the crystal conversion. is there.
[0033]
FIG. 2 shows the state of the primary particles of such a crystal. The observation in FIG. 2 was also performed by TEM, as in the case of FIG. Two very large primary particles are observed near the center of the photograph. The scale bar in the figure is 0.2 μm.
[0034]
In dispersing the titanyl phthalocyanine crystal thus produced, in order to make the particle size after dispersion small (approximately 0.2 μm or less), dispersion is performed by giving a strong shear, and further, if necessary. Dispersion is performed by giving strong energy to crush primary particles. As a result, as described above, some of the particles are transformed into a crystal form other than the desired crystal form.
[0035]
On the other hand, in the present invention, the range in which crystal growth hardly occurs during the crystal conversion (the size of the amorphous titanyl phthalocyanine particles observed in FIG. 1 is kept as small as that after the crystal conversion, approximately 0.2 μm or less. In this case, a titanyl phthalocyanine crystal having a primary particle size as small as possible is obtained by determining the point in time when the crystal conversion is completed. The particle size after the crystal conversion increases in proportion to the crystal conversion time. Therefore, as described above, it is important to increase the efficiency of crystal conversion and complete the conversion in a short time. There are several important points for this.
[0036]
One is to select an appropriate crystal conversion solvent as described above to increase the crystal conversion efficiency. The other is to use strong stirring to sufficiently contact the solvent and the aqueous paste of titanyl phthalocyanine (the raw material prepared as described above) in order to complete the crystal transformation in a short time. More specifically, a method of using a propeller having a very strong stirring power, or using an intense stirring (dispersion) means such as a homogenizer (homomixer) to realize crystal conversion in a short time. is there. Under these conditions, it is possible to obtain a titanyl phthalocyanine crystal in which the crystal conversion is sufficiently performed and no crystal growth occurs without leaving any raw material.
[0037]
Further, as described above, since the crystal grain size and the crystal conversion time are in a proportional relationship, a method of immediately stopping the reaction when a predetermined reaction (crystal conversion) is completed is also an effective means. As described above, a large amount of a solvent that is unlikely to undergo crystal conversion immediately after the crystal conversion as described above is added. Examples of the solvent that does not easily undergo crystal transformation include alcohol-based and ester-based solvents. Crystal conversion can be stopped by adding these solvents about 10 times to the crystal conversion solvent.
[0038]
The smaller the primary particle size produced in this way is, the better the result for the problem of the photoreceptor is. However, the next step (pigment filtration step) related to pigment production, the dispersion in the dispersion liquid, Considering stability, side effects may occur even if they are too small. That is, when the primary particles are very fine, there is a problem that the filtration time is very long in the step of filtering the primary particles. On the other hand, if the primary particles are too fine, the surface area of the pigment particles in the dispersion becomes large, and the possibility of reaggregation of the particles increases. Therefore, a suitable pigment particle size is in the range of about 0.05 μm to about 0.2 μm.
[0039]
FIG. 3 shows a TEM image of the titanyl phthalocyanine crystal when the crystal conversion is performed in a short time. Unlike the case of FIG. 2, the particle size is small and almost uniform, and no coarse particles as observed in FIG. 2 are observed at all. The scale bar in the figure is 0.2 μm.
[0040]
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 having 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. A known dryer can be used for the heating and drying. However, when the drying is performed in the atmosphere, a blower-type 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.
[0041]
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. This can disperse up to the primary particles by a usual dispersing apparatus. However, if the dispersing solvent of the crystal conversion solvent and the dispersion used subsequently is the same, it does not need to be dried. 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 does not need to disperse large lumps of secondary particles, and makes the effect of the present invention more remarkable.
[0042]
The thus obtained titanyl phthalocyanine crystal having primary particles of 0.2 μm or less is extremely useful as a charge generation material for an electrophotographic photoreceptor. In particular, a crystal form 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 of CuKα (wavelength 1.542 °) has extremely high photocarrier generation efficiency. It has. However, as described above, the crystal form is unstable and has a disadvantage that the crystal form is easily transferred when a dispersion is prepared. However, by synthesizing the primary particles as small as possible as in the present invention, a dispersion having a small average particle size can be produced without giving an excessive share at the time of producing the dispersion, and the crystal form is extremely small. It can be manufactured stably.
[0043]
A general method is used for preparing the dispersion, and the titanyl phthalocyanine crystal is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, a bead mill, ultrasonic waves, or the like. It is obtained. At this time, the binder resin may be selected according to the electrostatic characteristics of the photoreceptor, and the solvent may be selected according to the wettability to the pigment, the dispersibility of the pigment, and the like.
[0044]
Hereinafter, the electrophotographic photoreceptor of the present invention will be described with reference to the drawings.
FIG. 4 is a cross-sectional view showing the electrophotographic photoreceptor of the present invention. A charge generation layer (45) containing a charge generation material as a main component and a charge transport material as a main component are formed on a conductive support (41). And a charge transport layer (47).
FIG. 5 is a sectional view showing another configuration example of the electrophotographic photoreceptor of the present invention, in which a protective layer (49) is laminated on a charge generation layer (45) and a charge transport layer (47). Has taken.
[0045]
As the conductive support (41), a volume resistance of 10 ¹⁰ What 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 out, etc., then tubed, 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 (41).
[0046]
Among them, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. The aluminum referred to here includes both pure aluminum and aluminum alloy. Specifically, JIS 1000 series, 3000 series, and 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, it is excellent in preventing point defects (black spots, background stain) generated when used in reversal development (negative / positive development).
[0047]
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 to 4 A / dm ² The treatment is performed within the range of about 5 to 30 minutes and the treatment time is about 5 to 60 minutes, but the present invention is not limited to this. 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. 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 a single washing with pure water, but usually washing at another stage is performed. 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. The thickness of the anodic oxide film formed as described above is desirably about 5 to 15 μm. If it is too thin, the barrier effect of the anodic oxide film is not sufficient, and if it is too thick, the time constant of the electrode becomes too large, resulting in the generation of residual potential and reduced photoconductor response. May be.
[0048]
In addition, those 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 (41) 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 resin or photocurable resin 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.
[0049]
Further, a heat-shrinkable tube containing the above-mentioned conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chloride rubber, and polytetrafluoroethylene-based fluororesin on a suitable cylindrical substrate. A conductive layer provided with a conductive layer can also be favorably used as the conductive support (41) of the present invention.
[0050]
Next, the photosensitive layer will be described.
The charge generation layer (45) is a layer mainly composed of titanyl phthalocyanine crystal having an average primary particle size of 0.2 μm or less as a charge generation material. Preferably, it is a step of converting into a crystal form 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 characteristic X-ray (wavelength 1.542 °) of CuKα. . 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 between the 7.3 ° peak and the 9.4 ° peak is preferably used, and a titanyl phthalocyanine crystal having no peak at 26.3 ° is particularly preferably used. .
[0051]
The charge generation layer (45) is obtained by dispersing the pigment together with a binder resin as necessary in a suitable solvent using a ball mill, an attritor, a sand mill, ultrasonic waves, or the like, and applying the resultant on a conductive support; It is formed by drying.
If necessary, the binder resin used for the charge generation layer (45) includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, and polysulfone. -N-vinyl carbazole, polyacrylamide, 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. 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 charge generating substance.
[0052]
Examples of the solvent used here 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. As a method for applying the coating solution, a method such as a dip coating method, a spray coat, a beat coat, a nozzle coat, a spinner coat, and a ring coat can be used. The thickness of the charge generation layer (45) is suitably about 0.01 to 5 μm, and preferably 0.1 to 2 μm.
[0053]
The charge transporting layer (47) can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying this on the charge generating 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. 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.
[0054]
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.
[0055]
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.
[0056]
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.
[0057]
In the charge transport layer (47), 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, the polymer charge transport materials represented by the formulas (I) to (X) are preferably used, and these are exemplified below and specific examples are shown.
[0058]
Embedded image

Formula (I)
Where R ₁ , R ₂ , R ₃ Are each independently a substituted or unsubstituted alkyl group or halogen atom, R ₄ Is a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ , R ₆ Is 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, 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. In the formula (I), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0059]
Embedded image

R ₁₀₁ , R ₁₀₂ Each 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-, -SO ₂ —, —CO—, —CO—O—Z—O—CO— (wherein, Z represents an aliphatic divalent group) or
[0060]
Embedded image

(A is an integer of 1 to 20, b is an integer of 1 to 2000, R ₁₀₃ , R ₁₀₄ Represents a substituted or unsubstituted alkyl group or an aryl group). Where R ₁₀₁ And R ₁₀₂ , R ₁₀₃ And R ₁₀₄ May be the same or different. )
[0061]
Embedded image

Formula (II)
Where R ₇ , R ₈ Is a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ , Ar ₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (II), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0062]
Embedded image

Formula (III)
Where R ₉ , R ₁₀ Is a substituted or unsubstituted aryl group, Ar ₄ , Ar ₅ , Ar ₆ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (III), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0063]
Embedded image

(IV) formula
Where R ₁₁ , R ₁₂ Is a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , Ar ₉ Are the same or different arylene groups, and X, k, j and n are the same as in the formula (I). In the formula (IV), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0064]
Embedded image

(V) formula
Where R _Thirteen , R ₁₄ Is a substituted or unsubstituted aryl group, Ar ₁₀ , Ar ₁₁ , Ar ₁₂ Are the same or different arylene groups, X ₁ , X ₂ Represents 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 formula (I). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0065]
Embedded image

Formula (VI)
Where R _Fifteen , R ₁₆ , R ₁₇ , R ₁₈ Is a substituted or unsubstituted aryl group, Ar _Thirteen , Ar ₁₄ , Ar _Fifteen , Ar ₁₆ Are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ Represents 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, which may be the same or different. X, k, j and n are the same as in the case of the formula (I). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0066]
Embedded image

(VII) Formula
Where R ₁₉ , R ₂₀ Represents a hydrogen atom, a substituted or unsubstituted aryl group; ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (VII), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0067]
Embedded image

Formula (VIII)
Where R ₂₁ Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , Ar ₂₃ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (VIII), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0068]
Embedded image

(IX) Formula
Where R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ Is a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , Ar ₂₈ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (IX), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0069]
Embedded image

(X) formula
Where R ₂₆ , R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ , Ar ₃₁ Represents the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but may be a random copolymer.
[0070]
In addition, as the polymer charge transporting material used in the charge transporting layer, in addition to the above-described polymer charge transporting material, a monomer or oligomer having an electron donating group may be formed at the time of film formation of 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.
[0071]
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.
[0072]
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.
[0073]
In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer (47). 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 methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used. 1% by weight is suitable.
[0074]
As the binder resin, in addition to using the binder resin described for the charge transport layer (47) as it is, the binder resin described for the charge generation layer (45) may be mixed and 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, and the amount of the charge transporting substance is preferably 0 to 190 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the binder resin. 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. 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.
[0075]
In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided between the conductive support (41) 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, alcohol-soluble resins such as copolymerized nylon and 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.
[0076]
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 Al ₂ O ₃ Provided by anodic oxidation, organic substances such as polyparaxylylene (parylene) or SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ Also, 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.
[0077]
In the photoreceptor of the present invention, a protective layer (49) may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. Materials used for the protective layer (49) include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, and polyallyl sulfone. , Polybutylene, polybutylene terephthalate, polycarbonate, polyarylate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane And resins such as polyvinyl chloride, polyvinylidene chloride, and epoxy resin. Among them, polycarbonate or polyarylate can be most preferably used.
[0078]
The protective layer (49) further includes a fluorine resin such as polytetrafluoroethylene, a silicone resin, and an inorganic filler such as titanium oxide, tin oxide, potassium titanate, and silica for the purpose of improving abrasion resistance. Further, a dispersion of an organic filler or the like can be added.
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, antimony-doped tin oxide, 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. Further, among these, α-alumina having a hexagonal close-packed structure can be used most effectively.
[0079]
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, preferably about 30% by weight or less are good.
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.
[0080]
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.
[0081]
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.
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. The dispersion state of the particles is stabilized. 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 as the repulsive force of the particles increases due to an increase in the absolute value of the zeta potential, and the particles tend to aggregate and become unstable as the value approaches 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.
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.
[0082]
Further, as a filler which is less likely to cause image blur, a filler having a high electrical insulation property (a specific resistance of 10 ¹⁰ Ω · 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. In addition, among these fillers, α-alumina, which has high insulation properties, high thermal stability, and high wear resistance, has a hexagonal close-packed structure, is used to reduce image blur and improve wear resistance. Especially useful.
[0083]
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 differs depending on the filling rate, it is necessary to measure the powder under a certain condition. In the present invention, the specific resistance of the filler is 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. It measured and used this value. In the measuring device, the electrode area is 4.0 cm ² It 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. 10 ⁶ The 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.
[0084]
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 meter (Ando Electric).
[0085]
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. As the surface treatment agent, a conventionally used surface treatment agent 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, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , 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. 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. 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.
[0086]
Further, the protective layer (49) 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. The concentration here refers to 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.
[0087]
When the components other than the filler of the protective layer are composed of only a polymer, not only the mechanical abrasion resistance can be improved but also the chemical stability can be enhanced. Higher polymers have lower chemical reactivity than lower molecules, and have high resistance to oxidizing gas generated from the charging member or high resistance to sputtering effect by discharge. When a film having high abrasion resistance such as a protective layer is provided on the surface, the problem of image blurring due to repeated use becomes very prominent. This is thought to be due to adsorption of oxidizing gas and adhesion (adsorption) of a low-resistance substance to the surface of the photoreceptor. As described above, the protective layer composed of only the filler and the polymer component is employed. In this case, the number of adsorption sites is reduced, which shows a high effect on image blur.
[0088]
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, other known materials such as aC and a-SiC formed by a vacuum thin film forming method can be used as the protective layer.
[0089]
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, it produces a new effect that is not provided by a monochrome image forming apparatus.
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.
[0090]
Also, tandem type full color machines are becoming mainstream, and the printing speed has been greatly improved. For this reason, the output of business documents has been increasing, and the number of cases of outputting a format (a document) using, for example, a company logo has also increased. In such a case, since printing is performed only at a specific location, the bias in the use of the photoconductor is further increased.
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.
[0091]
In the present invention, an intermediate layer can 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.
[0092]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 6 is a schematic diagram for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modified examples also belong to the category of the present invention.
In FIG. 6, a photoreceptor (21) is provided with a charge generation layer containing a titanyl phthalocyanine crystal having an average primary particle size of 0.2 μm or less and a charge transport layer on a conductive support. The charging member (23), the pre-transfer charger (27), the transfer charger (30), the separation charger (31), and the pre-cleaning charger (33) include corotron, scorotron, solid state charger (solid state charger), and charging A known means such as a roller is used. As the charging member, one that is in contact with or close to the photoconductor 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. In particular, in a tandem-type full-color image forming apparatus, in addition to the problem of density unevenness of a halftone image due to charging unevenness occurring in the case of a monochrome image forming apparatus, it leads to a serious problem of lowering color balance (color reproducibility). By superimposing the AC component on the DC component, the above problem is greatly improved. However, if the conditions of the AC component (frequency and peak-to-peak voltage) are too large, the hazard to the photoconductor becomes large. In some cases, the deterioration of the photoconductor is accelerated. For this reason, the superposition of the AC component should be kept to the minimum necessary.
[0093]
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.
In addition, the charging member disposed close to the charging member is a type in which the charging member is disposed in a non-contact state so as to have a gap of 200 μm or less between the surface of the photosensitive member and the surface of the charging member. If this gap is too large, charging tends to be unstable, and if it is too small, the surface of the charging member may be contaminated if toner remaining on the photoreceptor exists. . Therefore, the gap is suitably in the range of 10 to 200 μm, preferably 10 to 100 μm. From the distance of the air gap, it is distinguished from a known charging wire type charger represented by a corotron and a scorotron, a contact charging member such as a contact type charging roller, a charging brush, and a charging blade.
[0094]
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 shape of a charging roller, disposing gap forming members at both ends of the non-image forming portion of the charging member, bringing only this portion into contact with the surface of the photoconductor, and disposing the image forming region in a non-contact manner, Alternatively, a method in which the gap forming member at both ends of the photoreceptor non-image forming portion is arranged, and only this portion is brought into contact with the surface of the charging member, and the image forming region is arranged 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. 7 shows an example of a proximity charging mechanism in which a gap forming member is arranged on the charging member side.
[0095]
As the transfer means, generally, the above-mentioned charger can be used. However, as shown in FIG. 6, a combination of a transfer charger (30) and a separation charger (31) is effective.
Further, an LD or LED is used as a light source of the image exposure section (25). For the light source such as the static elimination lamp (22), use all luminescent materials such as fluorescent lamp, tungsten lamp, halogen lamp, mercury lamp, sodium lamp, light emitting diode (LED), semiconductor laser (LD), and electroluminescence (EL). Can be. 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.
Such a light source or the like irradiates the photosensitive member 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.
[0096]
Now, the toner developed on the photoconductor (21) by the developing unit (26) is transferred to the transfer paper (29), but not all is transferred, and remains on the photoconductor (21). Toner also forms. Such toner is removed from the photoreceptor by the fur brush (34) and the blade (35). 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.
[0097]
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.
[0098]
FIG. 8 shows another example of the electrophotographic process according to the present invention. The photoreceptor (61) is provided with a charge generation layer containing a titanyl phthalocyanine crystal having an average primary particle size of 0.2 μm or less and a charge transport layer on a conductive support. Driven by the drive rollers (62a) and (62b), charging by the charger (63), image exposure by the light source (64), development (not shown), transfer using the charger (65), and transfer by the light source (66) Exposure before cleaning, cleaning with a brush (67), and static elimination with a light source (68) are repeatedly performed. In FIG. 8, the photosensitive member (61) (of course, the support is translucent) is irradiated with light for image exposure from the support side. Further, as the image exposure source (64), LD or LED is preferably used.
[0099]
The illustrated electrophotographic process is an example of an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 8, 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 the 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 exposed to light. Irradiation can also be performed.
[0100]
The image forming means as described above may be fixedly incorporated in a copying machine, 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) that includes a photoconductor, and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a discharging unit. There are many shapes and the like of the process cartridge. As a general example, there is one shown in FIG. The photoreceptor (76) is provided with a charge generation layer containing a titanyl phthalocyanine crystal having an average primary particle size of 0.2 μm or less and a charge transport layer on a conductive support.
[0101]
FIG. 10 is a schematic view for explaining a tandem-type full-color electrophotographic apparatus of the present invention, and the following modified examples also belong to the category of the present invention.
In FIG. 10, reference numerals (1C), (1M), (1Y), and (1K) denote drum-shaped photoconductors, and the photoconductors (1C), (1M), (1Y), and (1K) are shown in FIG. , Around which at least the charging members (2C), (2M), (2Y) and (2K), the developing members (4C), (4M), (4Y) and (4K), the cleaning members The members (5C), (5M), (5Y) and (5K) are arranged. The charging members (2C), (2M), (2Y) and (2K) are charging members constituting a charging device for uniformly charging the surface of the photoconductor. The surface of the photoconductor between the charging members (2C), (2M), (2Y), and (2K) and the developing members (4C), (4M), (4Y), and (4K) is exposed from an exposure member (not shown). The laser beams (3C), (3M), (3Y), and (3K) are irradiated to form electrostatic latent images on the photoconductors (1C), (1M), (1Y), and (1K). ing. The four image forming elements (6C), (6M), (6Y), and (6K) centered on such photoconductors (1C), (1M), (1Y), and (1K) are transferred to a transfer material. They are juxtaposed along a transfer conveyance belt (10) as a conveyance means. The transfer conveyance belt (10) includes the developing members (4C), (4M), (4Y), and (4K) of the image forming units (6C), (6M), (6Y), and (6K), and the cleaning member (5C). , (5M), (5Y), and (5K) are in contact with the photoconductors (1C), (1M), (1Y), and (1K), and hit the rear side of the transfer / conveyor belt (10) on the photoconductor side. Transfer brushes (11C), (11M), (11Y) and (11K) for applying a transfer bias are arranged on the surface (back surface). 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.
[0102]
In the color electrophotographic apparatus having the configuration shown in FIG. 10, 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) move in the direction of the arrow (the direction around the photoconductor). ), Which is charged by the charging members (2C), (2M), (2Y), and (2K), and then the laser beams (3C), (3M) are exposed by an exposure unit (not shown) arranged inside the photoconductor. ), (3Y) and (3K), an electrostatic latent image corresponding to each color image to be created is formed. Next, the latent images are developed by the developing members (4C), (4M), (4Y) and (4K) to form toner images. Developing members (4C), (4M), (4Y), and (4K) are developing members that develop with C (cyan), M (magenta), Y (yellow), and K (black) toners, respectively. The toner images of the respective colors formed on the photoconductors (1C), (1M), (1Y) and (1K) are superimposed on the transfer paper. The transfer paper (7) is sent out of the tray by a paper feed roller (8), temporarily stopped by a pair of registration rollers (9), and is transferred to a transfer conveyance belt (10) at the same time as the image formation on the photoconductor. Sent. The transfer paper (7) held on the transfer conveyance belt (10) is conveyed, and each color is transferred at a contact position (transfer portion) with each of the photoconductors (1C), (1M), (1Y) and (1K). The transfer of the toner image is performed. The toner image on the photoreceptor is formed by the transfer bias applied to the transfer brushes (11C), (11M), (11Y), and (11K) and the photoreceptors (1C), (1M), (1Y), and (1K). Is transferred onto the transfer paper (7) by the electric field formed from the potential difference of Then, the recording paper (7) on which the four color toner images are superposed through the four transfer units is conveyed to a fixing device (12), where the toner is fixed, and is discharged to a discharge unit (not shown). Further, the residual toner remaining on each of the photoconductors (1C), (1M), (1Y) and (1K) without being transferred in the transfer section is removed by cleaning devices (5C), (5M), (5Y) and (5Y). 5K). In the example of FIG. 10, 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. Also, when a black-only document is created, providing a mechanism that stops the image forming elements (6C), (6M), and (6Y) other than black can be particularly effectively used in the present invention. Further, in FIG. 10, 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 It requires less toner filming and can be used favorably.
[0103]
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 those apparatuses in the form of a process cartridge. . The process cartridge is one device (part) including a photoconductor and further including a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, a discharging unit, and the like.
[0104]
【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.
(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 with 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.
Sixty parts of the obtained crude titanyl phthalocyanine pigment subjected to the washing with hot water were stirred and dissolved in 1,000 parts of 96% sulfuric acid at 3 to 5 ° C. and filtered. The obtained sulfuric acid solution was dropped into 35,000 parts of ice water while stirring, and the precipitated crystals were filtered and then washed repeatedly with water until the washing liquid became neutral, to obtain a water paste of titanyl phthalocyanine pigment.
1500 parts of tetrahydrofuran is added to this water paste, and the mixture is vigorously stirred (2000 rpm) at room temperature by a homomixer (Kennis, MARK, f model). When the dark blue color of the paste changes to pale blue (20 minutes after the start of stirring) ), 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.
[0105]
(Example 2)
The same procedure as in Example 1 was carried out except that the crystal conversion solvent in Example 1 was changed from tetrahydrofuran to toluene, to obtain a titanyl phthalocyanine crystal. This is designated as Pigment 2.
[0106]
(Example 3)
The same procedure as in Example 1 was carried out except that the crystal conversion solvent in Example 1 was changed from tetrahydrofuran to methylene chloride, to obtain titanyl phthalocyanine crystals. This is designated as Pigment 3.
[0107]
(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the crystal conversion solvent in Example 1 was changed from tetrahydrofuran to 2-butanone, to obtain a titanyl phthalocyanine crystal. This is designated as Pigment 4.
[0108]
(Comparative Example 2)
At the time of the crystal conversion treatment with tetrahydrofuran in Example 1, according to the method of Synthesis Example 1 described in JP-A-2001-19871, the same treatment as in Example 1 was performed except that the crystal conversion time was set to 4 hours, A titanyl phthalocyanine crystal was obtained. This is designated as Pigment 5.
[0109]
(Comparative Example 3)
In Example 1, during the crystal conversion treatment with tetrahydrofuran, the crystal conversion time was set to 4 hours in accordance with the method of Synthesis Example 1 described in JP-A-2001-19871, and the mixture was further stored for 24 hours a day and the next day. Except for performing filtration, the same treatment as in Example 1 was performed to obtain titanyl phthalocyanine crystals. This is designated as Pigment 6.
[0110]
A part of the water paste prepared in Example 1 was diluted to about 1% by weight with ion-exchanged water, and the surface thereof was scooped with a copper net having a conductive treatment, and the particle size of titanyl phthalocyanine was changed to transmission electron. Observation was performed with a microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75,000 times. The average particle size was determined as follows.
The TEM image observed as described above is taken as a TEM photograph, and 30 projected titanyl phthalocyanine particles (near needle-like shape) are arbitrarily selected, and the size of the major axis is measured. The arithmetic average of the longer diameters of the 30 individuals measured was determined to be the average particle size.
The average particle size in the water paste in Example 1 determined by the above method was 0.06 μm.
[0111]
TEM observation of the titanyl phthalocyanine crystal after the crystal conversion immediately before filtration in Examples 1 to 3 and Comparative Examples 1 to 3 was performed in the same manner as in the above-mentioned water paste. Each was subjected to a predetermined crystal conversion treatment, and the liquid immediately before filtration was sampled, diluted with each crystal conversion solvent to about 1% by weight, and used for measurement. Table 1 shows the obtained average particle sizes. The titanyl phthalocyanine crystals produced in Examples 1 to 3 and Comparative Examples 1 to 3 were not the same in crystal shape, unlike water paste (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was performed with the length of the largest diagonal line of the crystal as the major axis.
[0112]
[Table 1]

[0113]
A part of the water paste obtained in Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain low crystalline titanyl phthalocyanine powder.
The X-ray diffraction spectra of the dried powder of the water paste obtained as described above and the titanyl phthalocyanine crystals obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured under the following conditions.
X-ray tube: Cu
Voltage: 40kV
Current: 20mA
Scanning speed: 1 ° / min
Scanning range: 3 ° to 40 °
Time constant: 2 seconds
[0114]
FIG. 11 shows an X-ray diffraction spectrum of the dried powder of the water paste.
In addition, the titanyl phthalocyanine crystals obtained in Examples 1 to 3 and Comparative Examples 2 to 3 showed the same X-ray diffraction spectrum in each case. Therefore, the titanyl phthalocyanine obtained in Example 1 as a representative example was used. FIG. 12 shows the X-ray diffraction spectrum of the crystal. The X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Example 1 was different from that of the titanyl phthalocyanine crystals obtained in Examples 1 to 3 and Comparative Examples 2 to 3 (the lowest angle was 7. 5 °). This is shown in FIG.
[0115]
(Comparative Example 4)
A pigment was prepared according to the method described in JP-A-1-299874. That is, the wet cake (water paste) prepared in Example 1 was dried, 1 g of the dried product was added to 50 g of polyethylene glycol, and a sand mill was performed for 1 hour together with 100 g of glass beads. After the crystal transition, the resultant was washed with dilute sulfuric acid and an aqueous solution of ammonium hydroxide in that order and dried to obtain a pigment. This is designated as Pigment 7.
[0116]
(Comparative Example 5)
A pigment was prepared according to the method described in JP-A-3-269064. That is, the wet cake prepared in Example 1 was dried, and 1 g of the dried product was stirred (50 ° C.) for 1 hour in a mixed solvent of 10 g of ion-exchanged water and 1 g of monochlorobenzene, and then washed with methanol and ion-exchanged water. Drying gave a pigment. This is designated as Pigment 8.
[0117]
(Comparative Example 6)
A pigment was prepared according to the method described in JP-A-2-8256. That is, 9.8 g of phthalodinitrile and 75 ml of 1-chloronaphthalene are stirred and mixed, and 2.2 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 completion of the reaction, the mixture was allowed to cool to 130 ° C., filtered while hot, 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 9.
[0118]
(Comparative Example 7)
Pigments were prepared according to the method described in JP-A 64-17066. That is, 5 parts of α-type TiOPc was subjected to a crystal conversion treatment with a sand grinder at 100 ° C. for 10 hours together with 10 g of salt and 5 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 designated as Pigment 10.
[0119]
(Comparative Example 8)
A pigment was prepared according to the method described in JP-A-11-5919. That is, after 20.4 parts of o-phthalodinitrile and 7.6 parts of titanium tetrachloride were heated and reacted in 50 parts of quinoline at 200 ° C. for 2 hours, the solvent was removed by steam distillation, and a 2% aqueous chloride solution was added. The product was purified with a 2% aqueous sodium hydroxide solution, washed with methanol and N, N-dimethylformamide, and dried to obtain 21.3 parts of titanyl phthalocyanine. 2 parts of this titanyl phthalocyanine is dissolved little by little 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 400 parts of ice water with high-speed stirring, and the precipitated crystals are filtered. The crystals are washed with distilled water until no acid remains, to obtain a wet cake. The cake (assuming the phthalocyanine content was 2 parts) was stirred in 100 parts of THF for about 5 hours, filtered, washed, and dried to obtain a pigment. This is designated as Pigment 11.
[0120]
X-ray diffraction spectra of the pigments prepared in Comparative Examples 4 to 8 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 2 shows the same evaluation results as in Table 1 above.
[0121]
[Table 2]

[0122]
(Example 4)
A dispersion having the following composition was prepared by bead milling under the following conditions (this is referred to as dispersion 1).
15 parts of titanyl phthalocyanine crystal (pigment 1) produced in Example 1
Polyvinyl butyral (Sekisui Chemical: BX-1) 10 parts
280 parts of 2-butanone
Using a commercially available bead mill disperser, a PSZ ball having a diameter of 0.5 mm was used, and all 2-butanone and pigment in which polyvinyl butyral was dissolved were charged. p. m. And the dispersion was stopped when the volume average particle diameter became smaller than 0.2 μm.
[0123]
(Example 5)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 2 (this was referred to as Dispersion 2).
[0124]
(Example 6)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 3 (this was referred to as Dispersion 3).
[0125]
(Example 7)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 4 (this was referred to as Dispersion 4).
[0126]
(Comparative Example 9)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 5 (this is referred to as Dispersion 5).
[0127]
(Comparative Example 10)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 6 (this is referred to as Dispersion 6).
[0128]
(Comparative Example 11)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 7 (this is referred to as Dispersion 7).
[0129]
(Comparative Example 12)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 8 (this was referred to as Dispersion 8).
[0130]
(Comparative Example 13)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 9 (this is referred to as Dispersion 9).
[0131]
(Comparative Example 14)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 10 (this is referred to as Dispersion 10).
[0132]
(Comparative Example 15)
A dispersion was prepared in the same manner as in Example 4 except that the titanyl phthalocyanine crystal in Example 4 was changed to Pigment 11 (this is referred to as dispersion 11).
[0133]
(Comparative Example 16)
In Comparative Example 10, the dispersion time was changed, the dispersion was performed until the time when the crystal form did not change, and the dispersion was stopped (this is referred to as dispersion liquid 12).
[0134]
The pigment particle size (volume average particle size) in the dispersions prepared in Examples 4 to 7 and Comparative Examples 9 to 16 was measured by HORIBA, Ltd .: CAPA700. Further, the prepared dispersion was dried and powdered, and the X-ray diffraction spectrum was measured in the same manner as described above. The results are shown in Table 3.
[0135]
[Table 3]

The peak of the arrow (26.3 °) in FIG. 14 newly appeared. A part of the crystal has changed to another crystal type.
[0136]
(Example 8)
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 25 μm charge transport layer were formed to produce a laminated photoreceptor.

[0137]
Embedded image

80 parts of methylene chloride
[0138]
(Example 9)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 2 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0139]
(Example 10)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 3 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0140]
(Example 11)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 4 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0141]
(Comparative Example 17)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 5 was used instead of Dispersion Liquid 1 as a coating liquid for the charge generation layer in Example 8.
[0142]
(Comparative Example 18)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 6 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0143]
(Comparative Example 19)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 7 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0144]
(Comparative Example 20)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 8 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0145]
(Comparative Example 21)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 9 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0146]
(Comparative Example 22)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 10 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0147]
(Comparative Example 23)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 11 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0148]
(Comparative Example 24)
A photoconductor was prepared by the same way as that of Example 8 except that Dispersion Liquid 12 was used instead of Dispersion Liquid 1 as the coating liquid for the charge generation layer in Example 8.
[0149]
The electrophotographic photoreceptors of Examples 8 to 11 and Comparative Examples 17 to 24 produced as described above were mounted on the electrophotographic apparatus shown in FIG. 6, and the image exposure light source was a 780 nm semiconductor laser (image writing using a polygon mirror). An image was output under the following charging conditions using a contact-type charging roller as a charging member.
Charging conditions:
DC bias: about -1600 V (set so that the potential of the unexposed portion on the surface of the photoconductor becomes -900 V)
Using a chart with a writing rate of 6%, printing was continuously performed on 20,000 sheets, and images at the initial stage and after 20,000 sheets were evaluated. In the image evaluation, a solid white image was output at the initial stage and after 20,000 sheets, and the background stain was evaluated (evaluated according to the following rank).
At the same time, in order to measure the surface potential (solid black image area) of the photoreceptor at the developing unit position, the initial and 20,000 sheets were measured using a jig capable of setting an electrometer at the position where the developing unit was mounted. Of the photoreceptor after image output was measured. Table 4 shows the results.
[0150]
[Table 4]

Ground dirt rank:
5: Almost no dirt,
4: Slightly
3: Actual use limit level,
2 or less: a level that cannot withstand actual use
[0151]
(Example 12)
A photoconductor was prepared by the same way as that of Example 8 except that the coating liquid for the charge transport layer in Example 8 was changed to the one having the following composition.
◎ Coating solution for charge transport layer
Polymer charge transport material of the following composition 10 parts
(Weight average molecular weight: about 140000)
[0152]
Embedded image

0.5 parts of additives with the following structure
[0153]
Embedded image

100 parts of methylene chloride
[0154]
(Example 13)
A photoconductor was prepared in the same manner as in Example 8, except that the thickness of the charge transport layer in Example 8 was set to 22 μm, a protective layer coating solution having the following composition was applied on the charge transport layer, and dried, and a protective layer of 3 μm was provided. Produced.
◎ Coating solution for protective layer
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
[0155]
Embedded image

α-Alumina fine particles 4 parts
(Specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0156]
(Example 14)
A photoconductor was prepared in the same manner as in Example 8, except that the thickness of the charge transport layer in Example 8 was set to 22 μm, a protective layer coating solution having the following composition was applied on the charge transport layer, and dried, and a protective layer of 3 μm was provided. Produced.
◎ Coating solution for protective layer
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
[0157]
Embedded image

4 parts of titanium oxide fine particles
(Specific resistance: 1.5 × 10 ¹⁰ Ω · cm, average primary particle size: 0.5 μm)
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0158]
(Example 15)
A photoconductor was prepared in the same manner as in Example 8, except that the thickness of the charge transport layer in Example 8 was set to 22 μm, a protective layer coating solution having the following composition was applied on the charge transport layer, and dried, and a protective layer of 3 μm was provided. Produced.
◎ Coating solution for protective layer
Polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 10 parts
7 parts of charge transport material of the following structural formula
[0159]
Embedded image

Tin oxide-antimony oxide powder 4 parts
(Specific resistance: 10 ⁶ Ω · cm, average primary particle size 0.4 μm)
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0160]
(Example 16)
A photoconductor was prepared in the same manner as in Example 8, except that the thickness of the charge transport layer in Example 8 was set to 22 μm, a protective layer coating solution having the following composition was applied on the charge transport layer, and dried, and a protective layer of 3 μm was provided. Produced.
◎ Coating solution for protective layer
17 parts of polymer charge transport material of the following structural formula
(Weight average molecular weight: about 140000)
[0161]
Embedded image

Alumina fine particles 4 parts
(Specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts
150 parts of tetrahydrofuran
[0162]
The electrophotographic photoreceptors of Examples 12 to 16 prepared as described above were mounted on the electrophotographic apparatus shown in FIG. 6 together with the photoreceptor of Example 8, and an image exposure light source was a 780 nm semiconductor laser (polygon mirror). As for (image writing), an image was output under the following charging conditions using a contact type charging roller as a charging member.
Charging conditions:
DC bias: -1600 V (set so that the potential of the unexposed portion on the surface of the photoconductor becomes -900 V)
Using a chart with a writing rate of 6%, printing was continuously performed on 50,000 sheets, and images at the initial stage and after 50,000 sheets were evaluated. For the image evaluation, a solid white image was output at the initial stage and after 50,000 sheets, and the background stain was evaluated (evaluated according to the following rank).
After outputting 50,000 sheets, 50 images were output in an environment of 30 ° C. and 90% RH.
Further, the amount of abrasion on the surface of the photoconductor at the output of 50,000 sheets was measured. Table 5 shows the above results.
[0163]
[Table 5]

Ground dirt rank:
5: Almost no dirt,
4: Slightly
3: Actual use limit level,
2 or less: a level that cannot withstand actual use
[0164]
(Example 17)
The photoreceptor prepared in Example 8 was mounted on the electrophotographic apparatus shown in FIG. 6, and the image exposure light source was a 780 nm semiconductor laser (image writing by a polygon mirror), and the charging member was charged as shown in FIG. An image was output under the following charging conditions using a charging member for close proximity (a gap between the photosensitive member and the charging member surface being 50 μm) in which an insulating tape having a thickness of 50 μm was wound around both ends of the roller.
Charging conditions:
DC bias: -1650 V (set so that the potential of the unexposed portion on the surface of the photoconductor becomes -900 V)
Using a chart with a writing rate of 6%, printing was continuously performed on 20,000 sheets, and images at the initial stage and after 20,000 sheets were evaluated. After 20,000 sheets, a halftone image was output and evaluated.
[0165]
(Example 18)
The evaluation performed in Example 17 was performed by changing the charging conditions as follows.
Charging conditions:
DC bias: -900V
AC bias: 2.0 kV (peak to peak), frequency: 1.5 kHz
[0166]
(Example 19)
Evaluation was performed in the same manner as in Example 18 except that the thickness of the insulating tape was changed and the gap was changed to 150 μm.
[0167]
(Example 20)
Evaluation was performed in the same manner as in Example 18 except that the thickness of the insulating tape was changed and the gap was changed to 250 μm.
Table 6 shows the results together with the results of Example 8.
[0168]
[Table 6]

[0169]
(Example 21)
A photoconductor was prepared by the same way as that of Example 8 except that the support used in Example 8 was changed to an aluminum cylinder (JIS 1050) having a diameter of 30 mm.
[0170]
(Example 22)
In Example 21, an aluminum cylinder (JIS1050) was subjected to the following anodic oxide film treatment, and then a charge generating layer and a charge transport layer were provided in the same manner as in Example 17 without providing an undercoat layer, thereby producing a photoreceptor. .
◎ Anodized film treatment
The surface of the support was mirror-polished, degreased and washed with water, immersed in an electrolytic bath of 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. Further, after water washing, 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 6 μm anodic oxide film formed thereon.
[0171]
(Comparative Example 25)
A photoconductor was prepared by the same way as that of Comparative Example 17 except that the support used in Comparative Example 17 was changed to an aluminum cylinder (JIS 1050) having a diameter of 30 mm.
[0172]
(Comparative Example 26)
A photoconductor was prepared by the same way as that of Comparative Example 24 except that the support used in Comparative Example 24 was changed to an aluminum cylinder (JIS 1050) having a diameter of 30 mm.
[0173]
The photoconductors of Examples 21 to 22 and Comparative Examples 25 to 26 manufactured as described above are mounted on an electrophotographic apparatus cartridge as shown in FIG. 9 and mounted on an image forming apparatus shown in FIG. The same photoreceptor is mounted on the image forming element), the image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror), and a 50 μm thick insulating layer is provided on both ends of a charging roller as shown in FIG. An image was output under the following charging conditions using a charging member for close proximity arrangement around which the tape was wound (a gap between the photosensitive member and the surface of the charging member was 50 μm).
Charging conditions:
DC bias: -800V
AC bias: 1.8 kV (peak to peak), frequency: 1.5 kHz
Using a full-color chart with a writing rate of 6%, printing was continuously performed on 20,000 sheets, and images at the initial stage and after 20,000 sheets were evaluated. For the image evaluation, a solid white image was output at the initial stage and after 20,000 sheets, and the background stain was evaluated. The color reproducibility after 20,000 sheets was evaluated using a chart for evaluating color reproducibility. Table 7 shows the results.
[0174]
[Table 7]

Ground dirt rank:
5: Almost no dirt,
4: Slightly
3: Actual use limit level,
2 or less: a level that cannot withstand actual use
[0175]
Finally, it will be verified whether the lowest angle peak of 7.3 ° of the Bragg angle 2θ, which is a feature of the titanyl phthalocyanine crystal of the present invention, is the same as the lowest angle 7.5 ° of a known material.
[0176]
(Measurement example 1)
The pigment (minimum angle 7.3 °) obtained in Example 1 was prepared in the same manner as the pigment described in JP-A-61-239248 (having the maximum diffraction peak at 7.5 °), and 3% 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.
[0177]
(Measurement example 2)
The pigment (lowest angle 7.5 °) obtained in Comparative Example 1 was prepared in the same manner as the pigment described in JP-A-61-239248 (having the maximum diffraction peak at 7.5 °), and 3% by weight. % And mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as above. FIG. 16 shows the X-ray diffraction spectrum of Measurement Example 2.
[0178]
In the spectrum of FIG. 15, two independent peaks of 7.3 ° and 7.5 ° exist on the low-angle side, and it can be seen that at least the 7.3 ° and 7.5 ° peaks are different. . On the other hand, in the spectrum of FIG. 16, the peak on the low angle side exists only at 7.5 °, which is clearly different from the spectrum of FIG.
From the above, it can be understood 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.
[0179]
【The invention's effect】
As apparent from the detailed and specific description above, according to the present invention, a titanyl phthalocyanine crystal having extremely small primary particles and a method for producing the same are provided. Further, there is provided a titanyl phthalocyanine crystal having high crystal stability and capable of obtaining a dispersion having a small particle size when a dispersion is prepared using the titanyl phthalocyanine pigment, and a method for producing the same.
The use of the titanyl phthalocyanine crystal provides a stable electrophotographic photoreceptor that does not lose its chargeability and does not increase its residual potential even after repeated use without losing high sensitivity. Further, an electrophotographic photoreceptor with less occurrence of abnormal images even when used repeatedly is provided.
Further, by using the photoreceptor, a stable electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus, which can perform high-speed printing and generate less abnormal images, are provided.
[Brief description of the drawings]
FIG. 1 is an electron micrograph showing a particle state of a preferred amorphous titanyl phthalocyanine of the present invention.
FIG. 2 is an electron micrograph of titanyl phthalocyanine after the crystal transformation of the present invention.
FIG. 3 is another electron micrograph of titanyl phthalocyanine after the crystal transformation of the present invention.
FIG. 4 is a cross-sectional view illustrating a configuration example of an electrophotographic photosensitive member used in the present invention.
FIG. 5 is a cross-sectional view showing another configuration example of the electrophotographic photosensitive member used in the present invention.
FIG. 6 is a schematic diagram for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.
FIG. 7 is a schematic view showing a proximity charging mechanism (a gap holding mechanism is formed on a charging member side).
FIG. 8 is a schematic view showing another example of the electrophotographic process of the present invention.
FIG. 9 is a schematic view showing an example of the electrophotographic process cartridge of the present invention.
FIG. 10 is another schematic view for explaining the tandem type full-color electrophotographic apparatus of the present invention.
FIG. 11 is a view showing an X-ray diffraction spectrum of a dry powder of a water paste.
FIG. 12 is a view showing an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Example 1.
13 is a view showing an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Example 1. FIG.
14 shows an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Example 9. FIG.
FIG. 15 is a view showing an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Measurement Example 1.
16 shows an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Measurement Example 2. FIG.
[Explanation of symbols]
1C, 1M, 1Y, 1K Drum photoreceptor
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
7 Transfer paper
8 Paper feed rollers
9 Registration roller
10 Transfer conveyor belt
11C, 11M, 11Y, 11K transfer brush
12 Fixing device
21 Photoconductor
22 Static elimination lamp
23 Charging member
25 Image exposure unit
26 Developing unit
27 Pre-Transfer Charger
28 Registration Roller
29 Transfer paper
30 Transfer Charger
31 Separate charger
32 Separating claws
33 Charger before cleaning
34 fur brush
35 blade
41 conductive support
45 charge generation layer
47 charge transport layer
49 Protective layer
50 Photoconductor
51 Charging roller
52 Gap forming member
53 metal shaft
54 Image formation area
55 Non-image forming area
61 Photoconductor
62a drive roller
62b drive roller
63 Charger
64 image exposure source
65 Transfer Charger
66 Exposure before cleaning
67 Cleaning brush
68 Static elimination light source
76 Photoconductor
77 Charger
78 Cleaning brush
79 Image exposure section
80 Developing roller

Claims (19)

As a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα, it has a maximum diffraction peak at least at 27.2 °, and further 9.4 ° and 9.6 °. , Having a major peak at 24.0 ° and having a peak at 7.3 ° as the lowest diffraction peak, with a peak between the 7.3 ° peak and the 9.4 ° peak. A titanyl phthalocyanine crystal having no primary particles and an average primary particle size of 0.2 μm or less. The titanyl phthalocyanine crystal according to claim 1, wherein the titanyl phthalocyanine further has no peak at 26.3 °. As a diffraction peak (± 0.2 °) at a Bragg angle of 2θ with respect to the characteristic X-ray (wavelength 1.542 °) of CuKα, it has a maximum diffraction peak at least at 7.0 to 7.5 °, and the half width of the diffraction peak. Is 1 チ or more, and the average size of the primary particles is 0.1 μm or less. The amorphous particles of amorphous or low-crystalline titanyl phthalocyanine are subjected to crystal transformation with an organic solvent in the presence of water. 3. The method for producing titanyl phthalocyanine crystals according to claim 1 or 2, wherein, before growing to 0.2 μm or more, the titanyl phthalocyanine after the crystal conversion is separated from the organic solvent and filtered. The titanyl phthalocyanine crystal according to claim 3, wherein the organic solvent contains at least one selected from tetrahydrofuran, toluene, methylene chloride, carbon disulfide, orthodichlorobenzene, and 1,1,2-trichloroethane. Manufacturing method. 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 contains the titanyl phthalocyanine crystal according to claim 1 or 2. An electrophotographic photosensitive member characterized by the following. The electrophotographic photosensitive member according to claim 5, wherein the charge transport layer contains a polymer charge transport material. The electrophotographic photosensitive member according to claim 5, wherein a protective layer is laminated on the charge transport layer. The electrophotographic photosensitive member according to claim 7, characterized in that it contains the protective layer Resistivity 10 over ¹⁰ Omega · cm inorganic pigments or metal oxide. The metal oxide is, specific resistance ¹⁰ 10 Ω · cm or more alumina, electrophotographic photosensitive member according to claim 8, wherein the titanium oxide is any one of silica. The electrophotographic photosensitive member according to claim 9, wherein the metal oxide is α-alumina having a specific resistance of 10 ¹⁰ Ω · cm or more. The electrophotographic photoreceptor according to any one of claims 8 to 10, wherein the protective layer contains a polymer charge transport material. The electrophotographic photoreceptor according to any one of claims 5 to 11, wherein a surface of a conductive support of the electrophotographic photoreceptor has been subjected to an anodic oxide film treatment. An image forming method in which at least charging, image exposure, development, and transfer are repeatedly performed on an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 5 to 12. A characteristic image forming method. An image forming apparatus including at least an image forming element including a charging unit, an image exposing unit, a developing unit, a transfer unit, and an electrophotographic photoreceptor, wherein the electrophotographic photoreceptor comprises An image forming apparatus comprising the electrophotographic photosensitive member according to any one of the above. The image forming apparatus according to claim 14, wherein a plurality of the image forming elements are arranged. The image forming apparatus according to claim 14, wherein the charging unit includes a charging member in contact with or close to the photosensitive member. 17. The image forming apparatus according to claim 16, wherein a gap between the charging member and the photoconductor is 200 [mu] m or less. 18. The image forming apparatus according to claim 16, wherein the charging unit superimposes an AC component on a DC component to charge the photoconductor. 13. 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 claim 5. Process cartridge for equipment.

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