JP2004198785A - Organic photoreceptor, image forming method, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor which forms a precise electrostatic latent image with little blur, prevents image defects such as black spots, white voids, environment memory and image blur, and can ensure high image quality with good image density, sharpness and gradation, and to provide an image forming method, an image forming apparatus and a process cartridge. <P>SOLUTION: The organic photoreceptor has, on a conductive support, a stacked structure consisting of: a charge generating layer containing a pigment of an addition product of titanyl phthalocyanine and a diol having hydroxyl groups on respective two adjacent carbon atoms; and one or more layers having a total thickness of 5 to 15 μm on the charge generating layer. The uppermost layer contains fluororesin particles. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３２】
一般式（１）中、Ｘ¹〜Ｘ⁴は水素原子、ハロゲン原子、アルキル基、あるいはアルコキシ基を表し、ｎ，ｍ，ｌ，ｋは０〜４の整数を表す。
【００３３】
本発明の２つの隣接する各炭素原子に水酸基を有するジオール（以下、単に隣接ジオールとも云う）とは、脂肪族炭化水素の隣り合う炭素原子に一つずつ水酸基があるもので、例えばエチレングリコール、１，２−プロパンジオール、１，２−ブタンジオール、２，３−ブタンジオール、１，２−ヘキサンジオール、グリセリンなどを挙げることができる。好ましくは一般式（２）、（３）で示されるような２つの隣接する各炭素原子が不斉炭素で構成される光学活性を有するジオールを挙げることができる。
【００３４】
【化２】

【００３５】
（一般式（２）及び一般式（３）中、Ｒ₃、Ｒ₄、Ｒ₅、Ｒ₆はそれぞれ独立にアルキル基を表す。）
上記Ｒ₃、Ｒ₄、Ｒ₅、Ｒ₆のアルキル基としては、メチル、エチル、プロピル基が好ましい。即ち、Ｒ₃〜Ｒ₆のアルキル基が比較的炭素数が少ないアルキル基である方がチタニルフタロシアニンとの付加体を形成しやすい。中でも、（２Ｒ，３Ｒ）−２，３−ブタンジオール及び（２Ｓ，３Ｓ）−２，３−ブタンジオールの少なくとも１つを用いたチタニルフタロシアニン付加体が最も好ましい。チタニルフタロシアニン付加体の構造は、例えば（２Ｒ，３Ｒ）−２，３−ブタンジオールとの付加体で表すと、下記で示されるようなチタニルフタロシアニンと（２Ｒ，３Ｒ）−２，３−ブタンジオールの脱水縮合により生成する付加体化合物と推定される。
【００３６】
【化３】

【００３７】
本発明のチタニルフタロシアニン付加体は上記隣接ジオールとチタニルフタロシアニンを各種溶媒中で室温あるいは加熱下に反応することで合成することができる。原料であるチタニルフタロシアニンはフタロニトリルと四塩化チタンから得る合成法、ジイミノイソインドリンとアルコキシチタンから得る合成法、フタロニトリルと尿素とアルコキシチタンから得る合成法等通常知られている何れの合成法も用いることが出来るが、特にはジイミノイソインドリンとアルコキシチタンから得られる塩素含有量の少ない高純度なチタニルフタロシアニンが好ましい。またチタニルフタロシアニンはアシッドペースト処理等の方法により無定形化してから隣接ジオールと反応させるものが好ましい。本発明のチタニルフタロシアニン付加体を得るには、隣接ジオールをチタニルフタロシアニンに対して０．５〜２．０モル当量を加え、反応させることが好ましく、必ずしもチタニルフタロシアニン化合物１．０モル当量に対して１．０モル当量以上の隣接ジオールを必要としない。これは本発明のチタニルフタロシアニン付加体が隣接ジオール付加チタニルフタロシアニンと隣接ジオール付加のないチタニルフタロシアニンとの混晶状態でも電荷発生物質として高感度で高性能な状態を保つことができるからと考えられる。
【００３８】
チタニルフタロシアニンとジオールとの反応は、広範囲な温度条件下で行うことができ、反応温度は２５〜３００℃の範囲が好ましく、５０〜１５０℃の範囲であることがより好ましい。
【００３９】
反応溶剤としては各種有機溶媒中を使用することができ、例えば、トルエン、ニトロベンゼン、ジクロロベンゼン、トリクロロベンゼン、α−クロロナフタレン等の芳香族系有機溶剤、シクロヘキサノン、メチルエチルケトン、メチルイソブチルケトン等のケトン系有機溶剤、テトラヒドロフラン、ジメチルセロソルブ等のエーテル系有機溶剤、酢酸ブチル等のエステル系有機溶剤、ジメチルホルムアミド、ジメチルスルホキシド等の非プロトン系極性有機溶剤、トリクロロエタン等のハロゲン系有機溶剤、ブタノール、オクタノール、ドデカノール等のアルコール系有機溶剤等を挙げることができる。
【００４０】
結晶形
また本発明のチタニルフタロシアニン付加体としては、Ｃｕ−Ｋα特性Ｘ線の回折スペクトルで、ブラッグ角（２θ）の８．０〜８．８に明確な回折ピーク（バックグランドと明確に区別できるピーク）を有する結晶構造を有することが好ましい。その他にも９．５°、２４．７°、２５．１°、２６．５°等に明確なピークを有してもよい。ブラッグ角（２θ）の８．０〜８．８に明確な回折ピークを有する結晶構造を有する本発明のチタニルフタロシアニン付加体は良好な感度特性と環境メモリによる画像むら、黒ポチ、画像ボケ等の画像欠陥の少ない特性を併せて有する。
【００４１】
本発明の有機感光体は、導電性支持体上にチタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料の電荷発生物質を含有する電荷発生層とその上に、電荷輸送物質を含有し、合計膜厚が５〜１５μｍである電荷輸送層を有する負帯電型有機感光体（負の静電潜像が形成される。）の構造を有しているが、電荷発生層の電荷発生物質はチタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料を主とすることにより、電荷発生層内で発生した電子は、比較的長い距離を移動し導電性基体に導通することができる。このため、電荷発生層を比較的厚い膜厚に構成しても、電子のトラップによる残留電位の上昇は防止される。電荷発生層の膜厚は０．３〜２．０μｍが好ましい。又、電荷発生層が前記範囲の膜厚をもてば、十分に顔料濃度をあげることが出来るので、デジタル画像形成で、一般的に用いられる像露光光、レーザ光やＬＥＤ光等の単波長光照射によるモアレ等の発生も防止することが出来る。その上、チタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料が導電性基体からのフリーキャリアの注入防止効果が著しく、反転現像での黒ポチの発生を顕著に改善する。
【００４２】
電荷発生層の膜厚が０．３μｍ未満では顔料濃度を十分に含有することができにくいため、露光電位の低下が不十分となり画像濃度が低下したり、レーザ光の干渉防止効果が小さくなったりしやすい。一方、２．０μｍより大きいと、電荷発生層内での電荷キャリアのトラップ密度が大きくなりやすく、環境メモリの画像むらや画像ボケが発生しやすい。好ましい電荷発生層の膜厚は０．３〜１．０μｍである。
【００４３】
一方、電荷発生層の上には少なくとも１層以上の積層構成を有し、その膜厚の合計が５〜１５μｍで且つ最上層がフッ素系樹脂粒子を含有することを特徴とする。即ち、前記したチタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料も電荷発生物質を含有する電荷発生層の上に合計膜厚が５〜１５μｍで且つ最上層がフッ素系樹脂粒子を含有する層を設けることにより、黒ポチが発生しにくく又白ヌケの発生も防止され、文字画像及び中間調画像の両方とも、鮮鋭性が改良された電子写真画像を得ることが出来る。
【００４４】
上記電荷発生層上の合計膜厚が５〜１５μｍの層構造は、複数の電荷輸送層から構成し、且つ最上層の電荷輸送層にフッ素系樹脂粒子を含有させた構成が好ましい。複数の電荷輸送層で構成した合計膜厚が５〜１５μｍの層構造は、電荷発生層で発生した電荷キャリアの拡散を小さくし、微細なドットで構成された潜像を十分な電位コントラストで再現することができる。該合計膜厚が５μｍ未満だと帯電電位が不十分になりやすく、１５μｍを超えると、該電荷キャリアの拡散が大きくなり、鮮鋭性が十分に改善されない。特に、電荷輸送層の合計膜厚を８〜１４μｍの範囲で構成した場合が、鮮鋭性の改善効果がより顕著である。
【００４５】
前記最上層の電荷輸送層に含有されるフッ素系樹脂粒子とはフッ素原子を含有した樹脂粒子を意味し、例えば、四フッ化エチレン樹脂、三フッ化塩化エチレン樹脂、六フッ化エチレンプロピレン樹脂、フッ化ビニル樹脂、フッ化ビニリデン樹脂、二フッ化二塩化エチレン樹脂及びこれらの共重合体のなかから１種あるいは２種以上を適宜選択するのが好ましいが、特に、四フッ化エチレン樹脂及びフッ化ビニリデン樹脂が好ましい。フッ素系樹脂粒子の分子量や粒子の粒径は、適宜選択することができ、特に制限されるものではない。
【００４６】
最上層の電荷輸送層はバインダー樹脂中にフッ素系樹脂粒子を含有する構成が好ましく、フッ素系樹脂粒子の割合は、粒子の粒径にも影響を受けるが、最上層全質量に対し、１〜５０質量％であることが好ましく、より好ましくは５〜４０質量％である。更に、最上層には電荷輸送物質が含有されていることが好ましい。
【００４７】
本発明の最上層には、分散性、結着性や耐候性を向上させる目的でカップリング剤や酸化防止剤等の添加剤を加えてもよい。
【００４８】
最上層のフッ素系樹脂粒子の分散方法としては、ホモジナイザー、ボールミル、サンドミル、ロールミル及び超音波といった方法が挙げられる。一次粒径の粒径まで分散可能であれば特に限定されるものではない。
【００４９】
また、フッ素系樹脂粒子の分散助剤として、各種の界面活性剤、例えばクシ型グラフトポリマー等を適宜混合してもさしつかえない。
【００５０】
最上層の膜厚は０．１〜４μｍであることが好ましい。０．１μｍ未満では表面硬度や強度が十分でなく耐久性が低下し易く、４μｍを超えると現像時に潜像によって形成されるコントラストポテンシャルが劣化し易い。より好ましくは０．２〜３．０μｍである。
【００５１】
最上層はクリーニング性及び耐汚染性を満足するために低表面エネルギーであることが好ましく、水の接触角で測定される低表面エネルギー性としては９０度以上が好ましい。９０度未満では電子写真プロセスによる繰り返し使用によって表面に帯電生成物やトナー、紙からもたらされる脱落物が付着し易く、クリーニング不良や表面抵抗の低下による潜像の劣化（画像流れ）を生じ易い。より好ましくは９５度以上である。
【００５２】
本発明に用いる有機感光体の中間層のバインダー樹脂中に無機粒子を含有させる構造を有することにより、導電性支持体からのフリーキャリア（導電性支持体から進入してくる電子やホール）のブロッキング性が向上し、黒ポチやカブリの発生を防止し、且つ現像性を増大させて、高階調で鮮鋭性が良好な電子写真画像を得ることができる。
【００５３】
本発明の中間層のバインダー樹脂としては、ポリアミド樹脂、エチレン系共重合樹脂、例えばＥＬＶＡＸ４２６０（デュポン社製）、ポリウレタン樹脂、例えばＮＬ２５３２（三井化学社製）、ＮＬ２２４９Ｅ（三井化学社製）、変性ポリオレフィン樹脂、例えばスーパクロン（日本製紙社製）、ＧＳ２０００（（株）鉛市）等が挙げられる。これらの中でも特にアルコール可溶性ポリアミドが好ましい。アルコール可溶性ポリアミドは、溶媒溶解性に優れ、且つ無機粒子の分散安定性も良好であり、バインダーと無機粒子の相乗効果により、前記フリーキャリアのブロッキング性が向上し、黒ポチ等の画像欠陥の防止に著しい効果を示す。
【００５４】
アルコール可溶性ポリアミドとしては、アルコキシメチル化ナイロン、共重合ナイロン等が挙げられる。例えば、メトキシメチル化ナイロン、ナイロン６／６６／６１０／１２共重合等が市販されている。
【００５５】
又、上記ポリアミド樹脂の分子量は数平均分子量で５，０００〜８０，０００が好ましく、１０，０００〜６０，０００がより好ましい。数平均分子量が５，０００以下だと中間層の膜厚の均一性が劣化し、本発明の効果が十分に発揮されにくい。一方、８０，０００より大きいと、樹脂の溶媒溶解性が低下しやすく、中間層中に凝集樹脂が発生しやすく、黒ポチ等の画像欠陥が発生しやすい。
【００５６】
本発明のポリアミド樹脂を溶解し、塗布液を作製する溶媒としては、エタノール、ｎ−プロピルアルコール、イソプロピルアルコール、ｎ−ブタノール、ｔ−ブタノール、ｓｅｃ−ブタノール等の炭素数２〜４のアルコール類が好ましく、ポリアミドの溶解性と作製された塗布液の塗布性の点で優れている。これらの溶媒は全溶媒中に３０〜１００質量％、好ましくは４０〜１００質量％、更には５０〜１００質量％が好ましい。前記溶媒と併用し、好ましい効果を得られる助溶媒としては、メタノール、ベンジルアルコール、トルエン、メチレンクロライド、シクロヘキサノン、テトラヒドロフラン等が挙げられる。
【００５７】
本発明の中間層に用いられる無機粒子は、酸化チタン（ＴｉＯ₂）、酸化亜鉛（ＺｎＯ）、酸化スズ（ＳｎＯ₂）、酸化ジルコニウム、酸化セリウム、酸化鉄、酸化アルミニウム、酸化タングステン、酸化ビスマス等の金属酸化物、炭化ケイ素、炭化チタン等の金属炭化物、チタン酸ストロンチウム、チタン酸カルシウム、チタン酸バリウム等のチタン酸塩、炭酸カルシウム等の炭酸塩、窒化アルミニウム等の金属窒化物、硫酸バリウム、硫酸銅、硫酸亜鉛等の硫酸塩等が挙げられる。これらの無機粒子の表面には他の金属酸化物でコーティングする方が好ましい。例えば、シリカ、アルミナ、ジルコニア、酸化スズ、酸化アンチモンドープされた酸化スズ等で、上記無機粒子の表面をコートし、無機粒子の表面に存在する水酸基を被覆し、耐湿性を改良する方が好ましい。中間層における粒子の含有率は、体積率にして１０％から９０％が好ましく、更には２５％から７５％が好ましい。
【００５８】
無機粒子の数平均１次粒子径は１０〜４００ｎｍであることが好ましい。該数平均１次粒子径とは、無機粒子を透過型電子顕微鏡観察によって１００００倍に拡大し、ランダムに１００個の粒子を１次粒子として観察し、画像解析によってフェレ方向平均径としての測定値である。
【００５９】
このような無機粒子を中間層に含有させると画像欠陥の１つであるレーザ光によるモアレを低減したり、中間層のフリーキャリア（導電性支持体等から進入してくる電子やホール）のブロッキング性を高めることができる。
【００６０】
又、本発明に用いる無機粒子はＮ型半導性粒子が好ましい。該Ｎ型半導性粒子とは、主たる電荷キャリアが電子である粒子を意味する。すなわち、主たる電荷キャリアが電子であることから、該Ｎ型半導性粒子を絶縁性バインダーに含有させた中間層は、基体からのホール注入を効率的にブロックし、また、感光層からの電子に対してはブロッキング性が少ない性質を有する。
【００６１】
前記Ｎ型半導性粒子は、具体的には酸化チタン（ＴｉＯ₂）、酸化亜鉛（ＺｎＯ）、酸化スズ（ＳｎＯ₂）等の無機粒子が挙げられるが、本発明では、特に酸化チタンが好ましく用いられる。
【００６２】
Ｎ型半導性粒子の平均粒径は、数平均１次粒径で１０ｎｍ以上４００ｎｍ以下の範囲が良く、１５ｎｍ〜２００ｎｍが好ましい。１０ｎｍ未満では中間層によるモアレ発生の防止効果が小さい。一方、４００ｎｍより大きいと、中間層塗布液のＮ型半導性粒子の沈降が発生しやすく、その結果中間層中のＮ型半導性粒子の均一分散性が悪く、又黒ポチも増加しやすい。数平均１次粒径が前記範囲のＮ型半導性粒子を用いた中間層塗布液は分散安定性が良好で、且つこのような塗布液から形成された中間層は黒ポチ発生防止機能の他、環境特性が良好で、且つ耐クラッキング性を有する。
【００６３】
Ｎ型半導性粒子の形状は、樹枝状、針状および粒状等の形状があり、このような形状のＮ型半導性粒子は、例えば酸化チタン粒子では、結晶型としては、アナターゼ型、ルチル型及びアモルファス型等があるが、いずれの結晶型のものを用いてもよく、また２種以上の結晶型を混合して用いてもよい。その中でもルチル型で且つ粒状のものが最も良い。
【００６４】
Ｎ型半導性粒子に行われる表面処理の１つは、複数回の表面処理を行い、かつ該複数回の表面処理の中で、最後の表面処理が反応性有機ケイ素化合物を用いた表面処理を行うものである。また、該複数回の表面処理の中で、少なくとも１回の表面処理がアルミナ、シリカ、及びジルコニアから選ばれる少なくとも１種類以上の表面処理を行い、最後に反応性有機ケイ素化合物を用いた表面処理を行うことが好ましい。
【００６５】
尚、アルミナ処理、シリカ処理、ジルコニア処理とはＮ型半導性粒子表面にアルミナ、シリカ、或いはジルコニアを析出させる処理を云い、これらの表面に析出したアルミナ、シリカ、ジルコニアにはアルミナ、シリカ、ジルコニアの水和物も含まれる。又、反応性有機ケイ素化合物の表面処理とは、処理液に反応性有機ケイ素化合物を用いることを意味する。
【００６６】
この様に、酸化チタン粒子の様なＮ型半導性粒子の表面処理を少なくとも２回以上行うことにより、Ｎ型半導性粒子表面が均一に表面被覆（処理）され、該表面処理されたＮ型半導性粒子を中間層に用いると、中間層内における酸化チタン粒子等のＮ型半導性粒子の分散性が良好で、かつ黒ポチ等の画像欠陥を発生させない良好な感光体を得ることができるのである。
【００６７】
また、該複数回の表面処理をアルミナ、シリカを用いて表面処理を行い、次いで反応性有機ケイ素化合物による表面処理を行うものが特に好ましい。
【００６８】
なお、前述のアルミナ、シリカの処理は同時に行っても良いが、特にシリカ処理を最初に行い、次いでアルミナ処理を行うことが好ましい。また、アルミナとシリカの処理をそれぞれ行う場合のアルミナ及びシリカの処理量は、アルミナよりもシリカの多いものが好ましい。
【００６９】
前記酸化チタン等のＮ型半導性粒子のアルミナ、シリカ、及びジルコニア等の金属酸化物による表面処理は湿式法で行うことができる。例えば、シリカ、又はアルミナの表面処理を行ったＮ型半導性粒子は以下の様に作製することができる。
【００７０】
Ｎ型半導性粒子として酸化チタン粒子を用いる場合、酸化チタン粒子（数平均１次粒子径：５０ｎｍ）を５０〜３５０ｇ／Ｌの濃度で水中に分散させて水性スラリーとし、これに水溶性のケイ酸塩又は水溶性のアルミニウム化合物を添加する。その後、アルカリ又は酸を添加して中和し、酸化チタン粒子の表面にシリカ、又はアルミナを析出させる。続いて濾過、洗浄、乾燥を行い目的の表面処理酸化チタンを得る。前記水溶性のケイ酸塩としてケイ酸ナトリウムを使用した場合には、硫酸、硝酸、塩酸等の酸で中和することができる。一方、水溶性のアルミニウム化合物として硫酸アルミニウムを用いたときは水酸化ナトリウムや水酸化カリウム等のアルカリで中和することができる。
【００７１】
なお、上記表面処理に用いられる金属酸化物の量は、前記表面処理時の仕込量にて酸化チタン粒子等のＮ型半導性粒子１００質量部に対して、０．１〜５０質量部、更に好ましくは１〜１０質量部の金属酸化物が用いられる。尚、前述のアルミナとシリカを用いた場合も例えば酸化チタン粒子の場合、酸化チタン粒子１００質量部に対して各々１〜１０質量部用いることが好ましく、アルミナよりもシリカの量が多いことが好ましい。
【００７２】
上記の金属酸化物による表面処理の次に行われる反応性有機ケイ素化合物による表面処理は以下の様な湿式法で行うことが好ましい。
【００７３】
即ち、有機溶剤や水に対して前記反応性有機ケイ素化合物を溶解または懸濁させた液に前記金属酸化物で処理された酸化チタンを添加し、この液をセラミックビーズを用いたメディア分散を行うことが好ましい。次にメディア分散後の分散液を濾過後、加熱処理をしながら、減圧乾燥し、表面を有機ケイ素化合物で被覆した酸化チタン粒子を得る。なお、有機溶剤や水に対して酸化チタンを分散させた懸濁液に前記反応性有機ケイ素化合物を添加しても構わない。
【００７４】
尚、本発明において酸化チタン粒子表面が反応性有機ケイ素化合物により被覆されていることは、光電子分光法（ＥＳＣＡ）、オージェ電子分光法（Ａｕｇｅｒ）、２次イオン質量分析法（ＳＩＭＳ）や拡散反射ＦＩ−ＩＲ等の表面分析手法を複合することによって確認されるものである。
【００７５】
前記表面処理に用いられる反応性有機ケイ素化合物の量は、前記表面処理時の仕込量にて前記金属酸化物で処理された酸化チタン１００質量部に対し、反応性有機ケイ素化合物を０．１〜５０質量部、更に好ましくは１〜１０質量部が好ましい。表面処理量が上記範囲よりも少ないと表面処理効果が十分に付与されず、中間層内における酸化チタン粒子の分散性等が悪くなる。また、上記範囲を超えてしまうと電気性能を悪化させる結果残留電位上昇や帯電電位の低下を招いてしまう。
【００７６】
本発明で用いられる反応性有機ケイ素化合物としては下記一般式（４）で表される化合物が挙げられるが、酸化チタン表面の水酸基等の反応性基と縮合反応をする化合物であれば、下記化合物に限定されない。
【００７７】
一般式（４）
（Ｒ）_n−Ｓｉ−（Ｘ）_4-n
（式中、Ｓｉはケイ素原子、Ｒは該ケイ素原子に炭素が直接結合した形の有機基を表し、Ｘは加水分解性基を表し、ｎは０〜３の整数を表す。）
一般式（４）で表される有機ケイ素化合物において、Ｒで示されるケイ素に炭素が直接結合した形の有機基としては、メチル、エチル、プロピル、ブチル、ペンチル、ヘキシル、オクチル、ドデシル等のアルキル基、フェニル、トリル、ナフチル、ビフェニル等のアリール基、γ−グリシドキシプロピル、β−（３，４−エポキシシクロヘキシル）エチル等の含エポキシ基、γ−アクリロキシプロピル、γ−メタアクリロキシプロピルの含（メタ）アクリロイル基、γ−ヒドロキシプロピル、２，３−ジヒドロキシプロピルオキシプロピル等の含水酸基、ビニル、プロペニル等の含ビニル基、γ−メルカプトプロピル等の含メルカプト基、γ−アミノプロピル、Ｎ−β（アミノエチル）−γ−アミノプロピル等の含アミノ基、γ−クロロプロピル、１，１，１−トリフロオロプロピル、ノナフルオロヘキシル、パーフルオロオクチルエチル等の含ハロゲン基、その他ニトロ、シアノ置換アルキル基を挙げられる。また、Ｘの加水分解性基としてはメトキシ、エトキシ等のアルコキシ基、ハロゲン基、アシルオキシ基が挙げられる。
【００７８】
また、一般式（４）で表される有機ケイ素化合物は、単独でも良いし、２種以上組み合わせて使用しても良い。
【００７９】
また、一般式（４）で表される有機ケイ素化合物の具体的化合物で、ｎが２以上の場合、複数のＲは同一でも異なっていても良い。同様に、ｎが２以下の場合、複数のＸは同一でも異なっていても良い。又、一般式（４）で表される有機ケイ素化合物を２種以上を用いるとき、Ｒ及びＸはそれぞれの化合物間で同一でも良く、異なっていても良い。
【００８０】
又、最後の表面処理に用いる好ましい反応性有機ケイ素化合物としてはポリシロキサン化合物が挙げられる。該ポリシロキサン化合物の分子量は１０００〜２００００のものが一般に入手しやすく、又、黒ポチ発生防止機能も良好である。
【００８１】
特にメチルハイドロジェンポリシロキサンを最後の表面処理に用いると良好な効果が得られる。
【００８２】
本発明の酸化チタンの表面処理の他の１つはフッ素原子を有する有機ケイ素化合物により表面処理を施された酸化チタン粒子である。該フッ素原子を有する有機ケイ素化合物による表面処理、前記した湿式法で行うのが好ましい。
【００８３】
即ち、有機溶剤や水に対して前記フッ素原子を有する有機ケイ素化合物を溶解または懸濁させ、この中に未処理の酸化チタンを添加し、このような溶液をメディア分散し、濾過、加熱処理を施した後に、乾燥し、酸化チタン表面をフッ素原子を有する有機ケイ素化合物で被覆する。なお、有機溶剤や水に対して酸化チタンを分散した懸濁液に前記フッ素原子を有する有機ケイ素化合物を添加しても構わない。
【００８４】
尚、前記酸化チタン表面がフッ素原子を有する有機ケイ素化合物によって被覆されていることは、光電子分光法（ＥＳＣＡ）、オージェ電子分光法（Ａｕｇｅｒ）、２次イオン質量分析法（ＳＩＭＳ）や拡散反射ＦＩ−ＩＲ等の表面分析装置を用いて複合的に確認することができる。
【００８５】
本発明に用いられるフッ素原子を有する有機ケイ素化合物としては、３，３，４，４，５，５，６，６，６−ノナフルオロヘキシルトリクロロシラン、３，３，３−トリフルオロプロピルトリメトキシシラン、メチル−３，３，３−トリフルオロプロピルジクロロシラン、ジメトキシメチル−３，３，３−トリフルオロプロピルシラン、３，３，４，４，５，５，６，６，６−ノナフルオロヘキシルメチルジクロロシラン等が挙げられる。
【００８６】
前記ポリアミド樹脂中に分散されるＮ型半導性粒子の量は、例えば表面処理酸化チタンの場合では、該バインダー樹脂１００質量部に対し、１０〜１０，０００質量部、好ましくは５０〜１，０００質量部である。該表面処理酸化チタンをこの範囲で用いることにより、該酸化チタンの分散性を良好に保つことができ、黒ポチの発生しない、良好な中間層を形成することができる。
【００８７】
又、本発明の中間層は実質的に絶縁層である。ここで絶縁層とは、体積抵抗が１×１０⁸〜１０¹⁵Ω・ｃｍである。又、本発明の中間層の体積抵抗は好ましくは１×１０⁹〜１０¹⁴Ω・ｃｍ、更に好ましくは、２×１０⁹〜１×１０¹³Ω・ｃｍが良い。体積抵抗は下記のようにして測定できる。
【００８８】
測定条件；ＪＩＳ：Ｃ２３１８−１９７５に準ずる。
測定器：三菱油化社製Ｈｉｒｅｓｔａ ＩＰ
測定条件：測定プローブ ＨＲＳ
印加電圧：５００Ｖ
測定環境：３０±２℃、８０±５ＲＨ％
体積抵抗が１×１０⁸未満では中間層の電荷ブロッキング性が低下し、黒ポチの発生が増大し、電子写真感光体の電位保持性も劣化し、良好な画質が得られない。一方１０¹⁵Ω・ｃｍより大きいと繰り返し画像形成で残留電位が増大しやすく、良好な画質が得られない。
【００８９】
本発明の中間層を形成するために作製する中間層塗布液は前記表面処理酸化チタン等の表面処理Ｎ型半導性粒子、バインダー樹脂、分散溶媒等から構成されるが、分散溶媒としては前記したポリアミド樹脂の溶媒と同様なものが適宜用いられる。
【００９０】
上記のような微粒子を本発明のポリアミド樹脂中に分散、含有させることにより、電子写真特性、特に繰り返し使用時の電位の湿度依存性、更に黒ポチ、画像むら、画像ボケ等の改善効果を増大させることができる。
【００９１】
又、本発明に用いる有機感光体は、以上のような構成を採用することにより、鮮鋭性を著しく改善でき、且つ電荷輸送層を薄膜化した場合に発生しやすい、黒ポチ、白ヌケ、環境メモリ、画像ボケ等の画像欠陥を防止し、電位性能が安定した有機感光体を提供することができる。
【００９２】
以下、上記以外の本発明に適用される有機感光体の構成について記載する。
本発明において、有機感光体とは電子写真感光体の構成に必要不可欠な電荷発生機能及び電荷輸送機能の少なくとも一方の機能を有機化合物に持たせて構成された電子写真感光体を意味し、公知の有機電荷発生物質又は有機電荷輸送物質から構成された感光体、電荷発生機能と電荷輸送機能を高分子錯体で構成した感光体等公知の有機感光体を全て含有する。
【００９３】
本発明の電荷輸送層とは、光露光により電荷発生層で発生した電荷キャリアを有機感光体の表面に輸送する機能を有する層を意味し、該電荷輸送機能の具体的な検出は、電荷発生層と電荷輸送層を導電性支持体上に積層し、光導伝性を検知することにより確認することができる。
【００９４】
本発明の有機感光体の層構成は、基本的には導電性支持体上に電荷発生層及び電荷輸送層の感光層から構成される。最も好ましい構成としては、感光層を電荷発生層と電荷輸送層で構成する。
【００９５】
以下に本発明に用いられる具体的な感光体の構成について記載する。
導電性支持体
本発明の感光体に用いられる導電性支持体としてはシート状或いは円筒状の導電性支持体が用いられる。
【００９６】
本発明の円筒状の導電性支持体とは回転することによりエンドレスに画像を形成できるに必要な円筒状の支持体を意味し、真直度で０．１ｍｍ以下、振れ０．１ｍｍ以下の範囲にある導電性の支持体が好ましい。この真直度及び振れの範囲を超えると、良好な画像形成が困難になる。
【００９７】
導電性支持体の材料としてはアルミニウム、ニッケルなどの金属ドラム、又はアルミニウム、酸化錫、酸化インジュウムなどを蒸着したプラスチックドラム、又は導電性物質を塗布した紙・プラスチックドラムを使用することができる。導電性支持体としては常温で比抵抗１０³Ωｃｍ以下が好ましい。
【００９８】
本発明で用いられる導電性支持体は、その表面に封孔処理されたアルマイト膜が形成されたものを用いても良い。アルマイト処理は、通常例えばクロム酸、硫酸、シュウ酸、リン酸、硼酸、スルファミン酸等の酸性浴中で行われるが、硫酸中での陽極酸化処理が最も好ましい結果を与える。硫酸中での陽極酸化処理の場合、硫酸濃度は１００〜２００ｇ／ｌ、アルミニウムイオン濃度は１〜１０ｇ／ｌ、液温は２０℃前後、印加電圧は約２０Ｖで行うのが好ましいが、これに限定されるものではない。又、陽極酸化被膜の平均膜厚は、通常２０μｍ以下、特に１０μｍ以下が好ましい。
【００９９】
中間層
本発明においては導電性支持体と感光層の間に、バリヤー機能を備えた前記した中間層を設ける。本発明の中間層の膜厚は０．２〜１０μｍが好ましく、０．５〜５μｍが最も好ましい。
【０１００】
感光層
電荷発生層
本発明の有機感光体には、電荷発生物質として前述のチタニルフタロシアニン付加体顔料を使用するが、他のフタロシアニン顔料、アゾ顔料、ペリレン顔料、アズレニウム顔料などを併用して用いることができる。
【０１０１】
電荷発生層にＣＧＭの分散媒としてバインダーを用いる場合、バインダーとしては公知の樹脂を用いることができるが、最も好ましい樹脂としてはホルマール樹脂、ブチラール樹脂、シリコーン樹脂、シリコーン変性ブチラール樹脂、フェノキシ樹脂等が挙げられる。バインダー樹脂と電荷発生物質との割合は、バインダー樹脂１００質量部に対し２０〜６００質量部が好ましい。これらの樹脂を用いることにより、繰り返し使用に伴う残留電位増加を最も小さくできる。電荷発生層の膜厚は０．３μｍ〜２μｍが好ましい。
【０１０２】
電荷輸送層
前記したように、本発明では電荷輸送層を複数の電荷輸送層から構成し、且つ最上層の電荷輸送層にフッ素系樹脂粒子を含有させた構成が好ましい。
【０１０３】
電荷輸送層には電荷輸送物質（ＣＴＭ）及びＣＴＭを分散し製膜するバインダー樹脂を含有する。その他の物質としては必要により前記したフッ素系樹脂粒子や酸化防止剤等の添加剤を含有しても良い。
【０１０４】
電荷輸送物質（ＣＴＭ）としては公知の正孔輸送性（Ｐ型）の電荷輸送物質（ＣＴＭ）を用いることが好ましい。例えばトリフェニルアミン誘導体、ヒドラゾン化合物、スチリル化合物、ベンジジン化合物、ブタジエン化合物などを用いることができる。これら電荷輸送物質は通常、適当なバインダー樹脂中に溶解して層形成が行われる。これらの中で繰り返し使用に伴う残留電位増加を最も小さくできるＣＴＭは高移動度で、且つ組み合わされるＣＧＭとのイオン化ポテンシャル差が０．５（ｅＶ）以下の特性を有するものであり、好ましくは０．３０（ｅＶ）以下である。
【０１０５】
ＣＧＭ、ＣＴＭのイオン化ポテンシャルは表面分析装置ＡＣ−１（理研計器社製）で測定される。
【０１０６】
電荷輸送層（ＣＴＬ）に用いられるバインダー樹脂としては熱可塑性樹脂、熱硬化性樹脂いずれの樹脂かを問わない。例えばポリスチレン、アクリル樹脂、メタクリル樹脂、塩化ビニル樹脂、酢酸ビニル樹脂、ポリビニルブチラール樹脂、エポキシ樹脂、ポリウレタン樹脂、フェノール樹脂、ポリエステル樹脂、アルキッド樹脂、ポリカーボネート樹脂、シリコーン樹脂、メラミン樹脂並びに、これらの樹脂の繰り返し単位構造のうちの２つ以上を含む共重合体樹脂。又これらの絶縁性樹脂の他、ポリ−Ｎ−ビニルカルバゾール等の高分子有機半導体が挙げられる。これらの中で吸水率が小さく、ＣＴＭの分散性、電子写真特性が良好なポリカーボネート樹脂が最も好ましい。
【０１０７】
バインダー樹脂と電荷輸送物質との割合は、バインダー樹脂１００質量部に対し５０〜２００質量部が好ましい。
【０１０８】
中間層、電荷発生層、電荷輸送層等の層形成に用いられる溶媒又は分散媒としては、ｎ−ブチルアミン、ジエチルアミン、エチレンジアミン、イソプロパノールアミン、トリエタノールアミン、トリエチレンジアミン、Ｎ，Ｎ−ジメチルホルムアミド、アセトン、メチルエチルケトン、メチルイソプロピルケトン、シクロヘキサノン、ベンゼン、トルエン、キシレン、クロロホルム、ジクロロメタン、１，２−ジクロロエタン、１，２−ジクロロプロパン、１，１，２−トリクロロエタン、１，１，１−トリクロロエタン、トリクロロエチレン、テトラクロロエタン、テトラヒドロフラン、ジオキソラン、ジオキサン、メタノール、エタノール、ブタノール、イソプロパノール、酢酸エチル、酢酸ブチル、ジメチルスルホキシド、メチルセロソルブ等が挙げられる。本発明はこれらに限定されるものではないが、ジクロロメタン、１，２−ジクロロエタン、メチルエチルケトン等が好ましく用いられる。また、これらの溶媒は単独或いは２種以上の混合溶媒として用いることもできる。
【０１０９】
次に有機感光体を製造するための塗布加工方法としては、浸漬塗布、スプレー塗布、円形量規制型塗布等の塗布加工法が用いられるが、感光層の上層側の塗布加工は下層の膜を極力溶解させないため、又、均一塗布加工を達成するためスプレー塗布又は円形量規制型（円形スライドホッパ型がその代表例）塗布等の塗布加工方法を用いるのが好ましい。なお保護層は前記円形量規制型塗布加工方法を用いるのが最も好ましい。前記円形量規制型塗布については例えば特開昭５８−１８９０６１号公報に詳細に記載されている。
【０１１０】
次に、本発明の有機感光体を用いた画像形成装置について説明する。
図６に示す画像形成装置１は、デジタル方式による画像形成装置であって、画像読取り部Ａ、画像処理部Ｂ、画像形成部Ｃ、転写紙搬送手段としての転写紙搬送部Ｄから構成されている。
【０１１１】
画像読取り部Ａの上部には原稿を自動搬送する自動原稿送り手段が設けられていて、原稿載置台１１上に載置された原稿は原稿搬送ローラ１２によって１枚宛分離搬送され読み取り位置１３ａにて画像の読み取りが行われる。原稿読み取りが終了した原稿は原稿搬送ローラ１２によって原稿排紙皿１４上に排出される。
【０１１２】
一方、プラテンガラス１３上に置かれた場合の原稿の画像は走査光学系を構成する照明ランプ及び第１ミラーから成る第１ミラーユニット１５の速度ｖによる読み取り動作と、Ｖ字状に位置した第２ミラー及び第３ミラーから成る第２ミラーユニット１６の同方向への速度ｖ／２による移動によって読み取られる。
【０１１３】
読み取られた画像は、投影レンズ１７を通してラインセンサである撮像素子ＣＣＤの受光面に結像される。撮像素子ＣＣＤ上に結像されたライン状の光学像は順次電気信号（輝度信号）に光電変換されたのちＡ／Ｄ変換を行い、画像処理部Ｂにおいて濃度変換、フィルタ処理などの処理が施された後、画像データは一旦メモリに記憶される。
【０１１４】
画像形成部Ｃでは、画像形成ユニットとして、像担持体であるドラム状の感光体２１と、その外周に、該感光体２１を帯電させる帯電手段（帯電工程）２２、帯電した感光体の表面電位を検出する電位検出手段２２０、現像手段（現像工程）２３、転写手段（転写工程）である転写搬送ベルト装置４５、前記感光体２１のクリーニング装置（クリーニング工程）２６及び光除電手段（光所電荷発生工程）としてのＰＣＬ（プレチャージランプ）２７が各々動作順に配置されている。また、現像手段２３の下流側には感光体２１上に現像されたパッチ像の反射濃度を測定する反射濃度検出手段２２２が設けられている。感光体２１には、本発明の有機感光体を使用し、図示の時計方向に駆動回転される。
【０１１５】
回転する感光体２１へは帯電手段２２による一様帯電がなされた後、像露光手段（像露光工程）としての露光光学系３０により画像処理部Ｂのメモリから呼び出された画像信号に基づいた像露光が行われる。書き込み手段である像露光手段としての露光光学系３０は図示しないレーザダイオードを発光光源とし、回転するポリゴンミラー３１、ｆθレンズ３４、シリンドリカルレンズ３５を経て反射ミラー３２により光路が曲げられ主走査がなされるもので、感光体２１に対してＡｏの位置において像露光が行われ、感光体２１の回転（副走査）によって静電潜像が形成される。本実施の形態の一例では文字部に対して露光を行い静電潜像を形成する。
【０１１６】
本発明の画像形成方法においては、感光体上に静電潜像を形成するに際し、像露光をスポット面積が２×１０^-9ｍ²以下の露光ビームを用いて行うことが好ましい。このような小径のビーム露光を行っても、本発明の有機感光体は、該スポット面積に対応した画像を忠実に形成することができる。より好ましいスポット面積は、０．０１×１０^-9〜１×１０^-9ｍ²である。その結果４００ｄｐｉ（ｄｐｉ：２．５４ｃｍ当たりのドット数）以上で、２５６階調を実現するところのきわめて優れた画像品質を達成することができる。
【０１１７】
前記露光ビームのスポット面積とは該ビーム光の強度がピーク強度の１／ｅ²以上の光強度に対応する面積で表される。
【０１１８】
用いられる露光ビームとしては半導体レーザを用いた走査光学系、及びＬＥＤや液晶シャッター等の固体スキャナー等があり、光強度分布についてもガウス分布及びローレンツ分布等があるがそれぞれのピーク強度の１／ｅ²までの部分をスポット面積とする。
【０１１９】
感光体２１上の静電潜像は現像手段２３によって反転現像が行われ、感光体２１の表面に可視像のトナー像が形成される。本発明の画像形成方法では、該現像手段に用いられる現像剤には重合トナーを用いることを特徴とする。形状や粒度分布が均一な重合トナーを本発明の有機感光体と併用することにより、より鮮鋭性が良好な電子写真画像を得ることができる。
【０１２０】
ここで、重合トナーとは、トナー用バインダーの樹脂の生成とトナー形状がバインダー樹脂の原料モノマーの重合、及びその後の化学的処理により形成されて得られるトナーを意味する。より具体的には懸濁重合、乳化重合等の重合反応と必要により、その後に行われる粒子同士の融着工程を経て得られるトナーを意味する。
【０１２１】
重合トナーは原料モノマーを水系で均一に分散した後に重合させトナーを製造することから、トナーの粒度分布、及び形状が均一なトナーが得られる。
【０１２２】
重合トナーは、懸濁重合法や、必要な添加剤の乳化液を加えた液中にて単量体を乳化重合し、微粒の重合粒子を製造し、その後に、有機溶媒、凝集剤等を添加して会合する方法で製造することができる。会合の際にトナーの構成に必要な離型剤や着色剤などの分散液と混合して会合させて調製する方法や、単量体中に離型剤や着色剤などのトナー構成成分を分散した上で乳化重合する方法などがあげられる。ここで会合とは樹脂粒子および着色剤粒子が複数個融着することを示す。
【０１２３】
即ち、重合性単量体中に着色剤や必要に応じて離型剤、荷電制御剤、さらに重合開始剤等の各種構成材料を添加し、ホモジナイザー、サンドミル、サンドグラインダー、超音波分散機などで重合性単量体に各種構成材料を溶解あるいは分散させる。この各種構成材料が溶解あるいは分散された重合性単量体を分散安定剤を含有した水系媒体中にホモミキサーやホモジナイザーなどを使用しトナーとしての所望の大きさの油滴に分散させる。その後、攪拌機構が後述の攪拌翼である反応装置へ移し、加熱することで重合反応を進行させる。反応終了後、分散安定剤を除去し、濾過、洗浄し、さらに乾燥することでトナーを調製する。
【０１２４】
また、本発明のトナーを製造する方法として樹脂粒子を水系媒体中で会合あるいは融着させて調製する方法も挙げることができる。この方法としては、特に限定されるものではないが、例えば、特開平５−２６５２５２号公報や特開平６−３２９９４７号公報、特開平９−１５９０４号公報に示す方法を挙げることができる。すなわち、樹脂粒子と着色剤などの構成材料の分散粒子、あるいは樹脂および着色剤等より構成される微粒子を複数以上会合させる方法、特に水中にてこれらを乳化剤を用いて分散した後に、臨界凝集濃度以上の凝集剤を加え塩析させると同時に、形成された重合体自体のガラス転移点温度以上で加熱融着させて融着粒子を形成しつつ徐々に粒径を成長させ、目的の粒径となったところで水を多量に加えて粒径成長を停止し、さらに加熱、攪拌しながら粒子表面を平滑にして形状を制御し、その粒子を含水状態のまま流動状態で加熱乾燥することにより、トナーを形成することができる。なお、ここにおいて凝集剤と同時に水に対して無限溶解する有機溶媒を加えてもよい。
【０１２５】
なお、本発明で用いられる形状係数等の均一なトナーを作製するための材料や製造方法、重合トナーの反応装置等については特開２０００−２１４６２９に詳細に記載されている。
【０１２６】
転写紙搬送部Ｄでは、画像形成ユニットの下方に異なるサイズの転写紙Ｐが収納された転写紙収納手段としての給紙ユニット４１（Ａ）、４１（Ｂ）、４１（Ｃ）が設けられ、また側方には手差し給紙を行う手差し給紙ユニット４２が設けられていて、それらの何れかから選択された転写紙Ｐは案内ローラ４３によって搬送路４０に沿って給紙され、給紙される転写紙Ｐの傾きと偏りの修正を行うレジストローラ対４４によって転写紙Ｐは一時停止を行ったのち再給紙が行われ、搬送路４０、転写前ローラ４３ａ、給紙経路４６及び進入ガイド板４７に案内され、感光体２１上のトナー画像が転写位置Ｂｏにおいて転写極２４及び分離極２５によって転写搬送ベルト装置４５の転写搬送ベルト４５４に載置搬送されながら転写紙Ｐに転写され、該転写紙Ｐは感光体２１面より分離し、転写搬送ベルト装置４５により定着手段５０に搬送される。
【０１２７】
定着手段５０は定着ローラ５１と加圧ローラ５２とを有しており、転写紙Ｐを定着ローラ５１と加圧ローラ５２との間を通過させることにより、加熱、加圧によってトナーを定着させる。トナー画像の定着を終えた転写紙Ｐは排紙トレイ６４上に排出される。
【０１２８】
以上は転写紙の片側への画像形成を行う状態を説明したものであるが、両面複写の場合は排紙切換部材１７０が切り替わり、転写紙案内部１７７が開放され、転写紙Ｐは破線矢印の方向に搬送される。
【０１２９】
更に、搬送機構１７８により転写紙Ｐは下方に搬送され、転写紙反転部１７９によりスイッチバックさせられ、転写紙Ｐの後端部は先端部となって両面複写用給紙ユニット１３０内に搬送される。
【０１３０】
転写紙Ｐは両面複写用給紙ユニット１３０に設けられた搬送ガイド１３１を給紙方向に移動し、給紙ローラ１３２で転写紙Ｐを再給紙し、転写紙Ｐを搬送路４０に案内する。
【０１３１】
再び、上述したように感光体２１方向に転写紙Ｐを搬送し、転写紙Ｐの裏面にトナー画像を転写し、定着手段５０で定着した後、排紙トレイ６４に排紙する。
【０１３２】
本発明の画像形成装置としては、上述の感光体と、現像器、クリーニング器等の構成要素をプロセスカートリッジとして一体に結合して構成し、このユニットを装置本体に対して着脱自在に構成しても良い。又、帯電器、像露光器、現像器、転写又は分離器、及びクリーニング器の少なくとも１つを感光体とともに一体に支持してプロセスカートリッジを形成し、装置本体に着脱自在の単一ユニットとし、装置本体のレールなどの案内手段を用いて着脱自在の構成としても良い。
【０１３３】
本発明の有機感光体は電子写真複写機、レーザプリンター、ＬＥＤプリンター及び液晶シャッター式プリンター等の電子写真装置一般に適応するが、更に、電子写真技術を応用したディスプレー、記録、軽印刷、製版及びファクシミリ等の装置にも幅広く適用することができる。
【０１３４】
【実施例】
以下、実施例をあげて本発明を詳細に説明するが、本発明の様態はこれに限定されない。尚、下記文中「部」とは「質量部」を表す。
【０１３５】
合成例１
チタニルフタロシアニン−アモルファス品の合成
１，３−ジイミノイソインドリン；２９．２ｇをオルトジクロルベンゼン２００ｍｌに分散し、チタニウムテトラ−ｎ−ブトキシド；２０．４ｇを加えて窒素雰囲気下に１５０〜１６０℃で５時間加熱する。放冷後、析出した結晶を濾過し、クロロホルムで洗浄、２％塩酸水溶液で洗浄、水洗、メタノール洗浄して、乾燥後、２６．２ｇ（収率９１％）の粗チタニルフタロシアニンを得る。ついで粗チタニルフタロシアニンを５℃以下で濃硫酸２５０ｍｌ中で１時間攪拌して溶解し、これを２０℃の水５Ｌに注ぎ込む。析出した結晶を濾過し、充分に水洗してウエットペースト品２２５ｇを得る。ついでウエットペースト品を冷凍庫にて凍結し、再度解凍した後、濾過、乾燥してチタニルフタロシアニン−アモルファス品２４．８ｇを得た。（収率８６％）
合成例２
チタニルフタロシアニン付加体ＣＧ−１の作製（（２Ｒ，３Ｒ）−２，３−ブタンジオール付加体）
トルエン２００ｍｌと（２Ｒ，３Ｒ）−２，３−ブタンジオール１．８ｇ（０．６モル当量）を溶解し、これにチタニルフタロシアニン−アモルファス品１９．６ｇを加える。次いでエステル管を備えて加熱還流し、生成する水をトルエンとの共沸によって除去しながら３時間反応させる。放冷後、（２Ｒ，３Ｒ）−２，３−ブタンジオール付加体を濾過し、メタノールで洗浄し、乾燥して目的とする付加体（ＣＧ−１）１９．８ｇを得た。ＣＧ−１のＸ線回折スペクトルを図１に示す。
【０１３６】
合成例３
チタニルフタロシアニン付加体ＣＧ−２の作製（（２Ｒ，３Ｒ）−２，３−ブタンジオール付加体）
トルエン２００ｍｌと（２Ｒ，３Ｒ）−２，３−ブタンジオール３．７ｇ（１．２モル当量）を溶解し、これにチタニルフタロシアニン−アモルファス品１９．６ｇを加える。次いでエステル管を備えて加熱還流し、生成する水をトルエンとの共沸によって除去しながら３時間反応させる。放冷後、（２Ｒ，３Ｒ）−２，３−ブタンジオール付加体を濾過し、メタノールで洗浄し、乾燥して目的とする付加体（ＣＧ−２）２０．７ｇを得た。ＣＧ−２のＸ線回折スペクトルを図２に示す。
【０１３７】
合成例４
チタニルフタロシアニン付加体ＣＧ−３の作製（（２Ｓ，３Ｓ）−２，３−ブタンジオール付加体）
オルトジクロロベンゼン２００ｍｌと（２Ｓ，３Ｓ）−２，３−ブタンジオール２．１ｇ（０．７モル当量）を溶解し、これにチタニルフタロシアニン−アモルファス品１９．６ｇを加える。次いで６時間加熱還流させ反応を進行させる。放冷後、（２Ｓ，３Ｓ）−２，３−ブタンジオール付加体を濾過し、メタノールで洗浄し、乾燥して目的とする付加体（ＣＧ−３）２０．０ｇを得た。ＣＧ−３のＸ線回折スペクトルを図３に示す。
【０１３８】
感光体１の作製
下記の様に感光体１を作製した。
【０１３９】
直径１００ｍｍφ、長さ３４６ｍｍの円筒形アルミニウム支持体の表面を切削加工し、表面粗さＲｚ＝１．５（μｍ）の導電性支持体を用意した。
〈中間層〉
下記中間層分散液を同じ混合溶媒にて二倍に希釈し、一夜静置後に濾過（フィルター；日本ポール社製リジメッシュ５μｍフィルター）し、中間層塗布液を作製した。
【０１４０】

を混合し、分散機としてサンドミルを用い、バッチ式で１０時間の分散を行い、中間層分散液を作製した。
【０１４１】
上記塗布液を用いて前記支持体上に、乾燥膜厚１．０μｍとなるよう塗布した。
【０１４２】
〈電荷発生層：ＣＧＬ〉

上記組成物を混合し、サンドミルを用いて分散し、電荷発生層塗布液を調製した。この塗布液を浸漬塗布法で塗布し、前記中間層の上に乾燥膜厚０．５μｍの電荷発生層を形成した。
【０１４３】
〈電荷輸送層１（ＣＴＬ１）〉

を混合し、溶解して電荷輸送層塗布液１を調製した。この塗布液を前記電荷発生層の上に浸漬塗布法で塗布し、１１０℃７０分の乾燥を行い、乾燥膜厚１０．０μｍの電荷輸送層１を形成した。
【０１４４】
〈４−フッ化エチレン樹脂粒子分散液の調製〉

を混合した後ガラスビーズを用いたサンドグラインダー（（株）アメックス製）にて分散し、４−フッ化エチレン樹脂粒子分散液を調製した。
【０１４５】
〈電荷輸送層２（ＣＴＬ２）〉

を混合し、溶解して電荷輸送層塗布液２を調製した。この塗布液を前記電荷輸送層１の上に円形スライドホッパ型塗布機で塗布し、１１０℃７０分の乾燥を行い、乾燥膜厚２．０μｍの電荷輸送層２を形成し、感光体１を作製した。
【０１４６】
尚、上記電荷発生層を透明ペットベース上に塗布乾燥した試料を用いて、Ｘ線回折スペクトルを測定したデータを図４に示す。図４のＸ線回折スペクトルは電荷発生層のバインダー（ポリビニルブチラール樹脂）の影響を受け、図１のＣＧ−１の顔料のＸ線回折スペクトルに比し、０．２°〜０．３°低角度側にシフトしている。
【０１４７】
感光体２〜１１の作製
感光体１の作製において、中間層の無機粒子、電荷発生層（ＣＧＬ）の膜厚、電荷輸送層１及び２（ＣＴＬ１及び２）の膜厚及びフッ素系樹脂粒子を表１のように変化させた以外は感光体１と同様にして感光体２〜１１を作製した。
【０１４８】
感光体１２〜１３の作製
感光体１の作製において、電荷発生層のＣＧ−１の代わりにＣＧ−２、ＣＧ−３を用い、電荷輸送層２のフッ素系樹脂粒子を表１のように変更した以外は感光体１と同様にして感光体１２〜１３を作製した。
【０１４９】
感光体１４の作製
感光体１において、中間層の無機粒子を除き、膜厚を０．５μｍに代えた以外は同様にして感光体１４を作製した。
【０１５０】
感光体１５の作製
感光体１において、電荷発生層のＣＧ−１をＹ−ＴｉＯＰｃに代えた以外は同様にして感光体１５を作製した。尚、Ｙ−ＴｉＯＰｃはＸ線回折スペクトルで、２７．２°に最大ピークを有するＹ型チタニルフタロシアニン顔料（表１ではＹ−ＴｉＯＰｃ）であり、下記合成例により合成した顔料である。
【０１５１】
Ｙ型チタニルフタロシアニン顔料の合成例
ジイミノイソインドリンとチタニウムテトラブトキシドからチタニルフタロシアニン粗品を作り、これを硫酸に溶かし水に注いで生じた沈殿を濾過し水で十分に洗って無定型チタニルフタロシアニン顔料含水ペーストを得る。この顔料含水ペースト（固形分換算約１０ｇ）をオルトジクロルベンゼン１００ｍｌと水１００ｍｌの混合液（水層は分離している）に分散し、７０℃で６時間加熱後、メタノールに注いで生じた結晶を濾過し、乾燥してＹ型チタニルフタロシアニン顔料（Ｙ−ＴｉＯＰｃ：Ｘ線回折スペクトルは図５）を得た。
【０１５２】
感光体１６の作製
感光体１の作製において、電荷輸送層２を除いた他は同様にして感光体１６を作製した。
【０１５３】
感光体１〜１６の中間層の体積抵抗は全て１０⁸Ω・ｃｍ以上であった。
【０１５４】
【表１】

【０１５５】
表１中、微粒子の表面処理のＩ、Ｊ、Ｋは下記処理を示す。
Ｉ：シリカ・アルミナ処理及びメチルハイドロジェンポリシロキサン処理
Ｊ：シリカ・アルミナ処理及びオクチルトリメトキシシラン処理
Ｋ：シリカ・ジルコニア処理及びメチルトリメトキシシラン処理
Ｇ、Ｈは下記のフッ素系樹脂微粒子を示す。
【０１５６】
Ｇ：四フッ化エチレン樹脂粒子（ルブロンＬ−２、ダイキン工業（株）製）
Ｈ：三フッ化エチレン樹脂粒子（ダイフロン、ダイキン工業（株）製）
《評価》
次いで、上記各感光体をコニカ製Ｓｉｔｉｏｓ７０４０デジタル複写機に搭載して、画像形成し、評価した。即ち、上記感光体を図６の構造を基本的に有するコニカ製Ｓｉｔｉｏｓ７０４０デジタル複写機（スコロトロン帯電器、半導体レーザ像露光器、反転現像手段を有する）に設定し、複写実験を行った。この実験においては図６のプロセス制御部のメモリー中に未露光部目標電位のプログラムを組み込み、自動的に現像位置の未露光部目標電位が設定されるようにデジタル複写機を改造した。
【０１５７】
《画像評価》
上記Ｓｉｔｉｏｓ７０４０デジタル複写機改造機に各感光体を取り付け、高温高湿（３０℃、８０％ＲＨ）環境でＡ４紙、５万枚の画素率７％の文字画像の複写を行い、スタート時及び１万枚コピー毎に白画像及びハーフトーン画像の複写を行い、黒ポチ、白ヌケ等の画像欠陥の有無を確認した。表２に結果を示す。
【０１５８】
尚、上記７０４０を用いたその他の評価条件は下記の条件に設定した。
帯電条件
帯電器；スコロトロン帯電器
現像位置の未露光部電位（ＶＨ）目標：−５００Ｖ
露光条件
露光部電位目標：−５０Ｖにする露光量に設定。
【０１５９】
露光ビーム：ドット密度４００ｄｐｉの像露光を行った。レーザビームスポット面積：０．８×１０^-9ｍ²、レーザは６８０ｎｍの半導体レーザを使用
現像条件
現像剤は、体積平均粒径５０μｍのフェライトをコアとして絶縁性樹脂をコーティングしたキャリアとスチレンアクリル系樹脂を主材料としてカーボンブラックの着色剤と荷電制御剤と低分子量ポリオレフィンからなる重合法で作製した体積平均粒径５．３μｍの着色粒子に、シリカ、酸化チタンを外添したトナーの現像剤を使用した。
【０１６０】
転写条件
転写極；コロナ帯電方式
分離条件：分離爪ユニットの分離手段を用いた
クリーニング条件
クリーニング部に硬度７０°、反発弾性６５％、厚さ２（ｍｍ）、自由長９ｍｍのクリーニングブレードをカウンター方向に線圧１８（ｇ／ｃｍ）となるように重り荷重方式で当接した。
【０１６１】
黒ポチ画像欠陥の評価基準
黒ポチについては、周期性が感光体の周期と一致し、目視できる黒ポチが、Ａ４サイズ当たり何個あるかで判定した。
【０１６２】
◎：０．４ｍｍ以上の黒ポチ頻度：全ての複写画像が３個／Ａ４以下（良好）
○：０．４ｍｍ以上の黒ポチ頻度：４個／Ａ４以上、１０個／Ａ４以下が１枚以上発生（実用上問題なし）
×：０．４ｍｍ以上の黒ポチ頻度：１１個／Ａ４以上が１枚以上発生（実用上問題有り）
白ヌケ画像欠陥の評価基準
白ヌケについては、周期性が感光体の周期と一致し、目視できる白ヌケが、Ａ４サイズ当たり何個あるかで判定した。
【０１６３】
◎：０．４ｍｍ以上の白ヌケ頻度：全ての複写画像が５個／Ａ４以下（良好）
○：０．４ｍｍ以上の白ヌケ頻度：６個／Ａ４以上、２０個／Ａ４以下が１枚以上発生（実用上問題なし）
×：０．４ｍｍ以上の白ヌケ頻度：２１個／Ａ４以上が１枚以上発生（実用上問題有り）
環境メモリ
環境メモリ：上記Ｓｉｔｉｏｓ７０４０複写機をＨＨ下に２４ｈｒ放置後、低湿低温下（ＬＬ：２０ＲＨ％、１０℃）に置き、３０分後、コピーした。オリジナル画像で０．４の濃度のハーフトーン画像を０．４の濃度にコピー、コピー画像の濃度差（ΔＨＤ＝最大濃度−最小濃度）で判定
◎：ΔＨＤが０．０５以下（良好）
○：ΔＨＤが０．０５より大で０．１未満（実用上問題なし）
×：ΔＨＤが０．１以上（実用上問題あり）
画像ボケ
０．１ｍｍ間隔の線で作製された５ｃｍの幅の格子画像を有するオリジナル画像を用いて高温高湿環境（３３℃／８０％ＲＨ）にて画像を形成し、画像を２０倍に拡大し、線の鮮鋭性、独立性を観察した。
【０１６４】
◎：画像ボケがなく、各線画像がオリジナル画像の±２０％の範囲で、再現されている（良好）
○：画像ボケが少なく、各線画像がオリジナル画像の±（２１〜４０％）の範囲で、再現されている（実用上問題なし）
△：画像ボケが大きく、各線画像がオリジナル画像の±（４１〜７５％）の範囲で、再現されている（高階調性画質としては不適）
×：画像ボケが著しく、各線画像がオリジナル画像の±７６％以上、又は線間隔がつぶれている（実用上問題あり）
画像濃度、階調性及び鮮鋭性の評価
上記評価条件を常温常湿（２０℃、６０％ＲＨ）環境に変更し、白画像から黒ベタ画像まで５０段階の階調段差を持つオリジナル画像を複写し、画像濃度と階調性を評価した。評価は複写画像の階調濃度をマクベス社製ＲＤ−９１８を使用して測定。紙の反射濃度を「０」とした相対反射濃度で測定した。
【０１６５】
（画像濃度）
◎：黒ベタ部濃度が１．３以上（良好）
○：黒ベタ部濃度が１．０〜１．３未満（実用上問題なし）
△：黒ベタ部濃度が０．７〜１．０未満（再評価が必要）
×：黒ベタ部濃度が０．７未満（実用上問題あり）
（階調性）
◎：階調性が２５段階以上（良好）
○：階調性が１５〜２４段階（実用上問題なし）
△：階調性が５〜１４段階（高階調性画質としては不適）
×：階調性が４段階以下（実用上問題あり）
（鮮鋭性）
画像の鮮鋭性は、環境条件の厳しい高温高湿（３０℃、８０％ＲＨ）環境において画像を出し、文字潰れで評価した。文字サイズ（ポイント）が異なる文字画像を形成し、下記の判断基準で評価した。
【０１６６】
◎：４ポイント以下の文字が明瞭であり、容易に判読可能（良好）
○：６ポイント以下の文字が明瞭であり、容易に判読可能（実用上問題なし）
△：８ポイント以下の文字が明瞭であり、容易に判読可能（再評価が必要）
×：８ポイントの文字の一部又は全部が判読不能（実用上問題あり）
【０１６７】
【表２】

【０１６８】
表２から明らかなように、本発明の感光体の条件（チタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料の電荷発生物質を含有する電荷発生層及び合計膜厚が５〜１５μｍの電荷輸送層、且つ最上層の電荷輸送層がフッ素系樹脂粒子を含有する感光体）Ｎｏ．１〜３、６〜１４は黒ポチ、白ヌケ、環境メモリ、画像ボケ、画像濃度、階調性、鮮鋭性の各評価項目とも、本発明外の感光体Ｎｏ．４、５、１５、１６に対し、良好な結果を達成している。特に、チタニルフタロシアニンと２つの隣接する各炭素原子に水酸基を有するジオールとの付加体顔料を用い、最上層の電荷輸送層がフッ素系樹脂粒子を含有する感光体（Ｎｏ．１〜３、６〜９、１４）は改善効果が著しい。一方、電荷輸送層の合計膜厚が１６μｍの感光体４は、画像ボケが劣り、鮮鋭性も低下しており、電荷輸送層の合計膜厚が４μｍの感光体５は帯電電位が目標の５００Ｖに達せず、画質が全体に低下している。又、電荷発生物質がＰ型顔料のみの感光体１５は環境メモリが劣り、鮮鋭性も低下している。又、最上層の電荷輸送層がフッ素系樹脂粒子を含有していない感光体１６は黒ポチ、白ヌケが多発し、鮮鋭性も低下している。
【０１６９】
【発明の効果】
本発明の有機感光体を用いることにより、黒ポチ、白ヌケ、環境メモリ、画像ボケ等の画像欠陥の発生が少なく、且つ、高い画像濃度及び高階調性の電子写真画像が得られる。又、本発明の有機感光体を用いた良好な電子写真画像を形成できる画像形成方法、画像形成装置を提供することが出来る。
【図面の簡単な説明】
【図１】ＣＧ−１のＸ線回折スペクトルの図である。
【図２】ＣＧ−２のＸ線回折スペクトルの図である。
【図３】ＣＧ−３のＸ線回折スペクトルの図である。
【図４】感光体１の電荷発生層のＸ線回折スペクトルを示す図である。
【図５】Ｙ型チタニルフタロシアニン顔料のＸ線回折スペクトルの図である。
【図６】本発明の画像形成装置の機能が組み込まれた概略図である。
【符号の説明】
１ 画像形成装置
２１ 感光体
２２ 帯電手段
２３ 現像手段
２４ 転写極
２５ 分離極
２６ クリーニング装置
３０ 露光光学系
４５ 転写搬送ベルト装置
５０ 定着手段
２５０ 分離爪ユニット[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic photoreceptor used in the field of copying machines and printers, and an image forming method, an image forming apparatus, and a process cartridge using the organic photoreceptor.
[0002]
[Prior art]
In recent years, organic photoconductors have been widely used as electrophotographic photoconductors. Organic photoreceptors have advantages over other photoreceptors such as easy development of materials corresponding to various exposure light sources from visible light to infrared light, selection of materials without environmental pollution, and low manufacturing cost. However, disadvantages include poor mechanical strength and poor chemical durability, deterioration of the electrostatic characteristics of the photoreceptor at the time of printing a large number of sheets, and generation of surface scratches.
[0003]
That is, since an electrical or mechanical external force is directly applied to the surface of an organic photoreceptor (hereinafter, also simply referred to as a photoreceptor) by a charging unit, a developing unit, a transfer unit, a cleaning unit, and the like, durability against these is required. You.
[0004]
Specifically, the photoreceptor is required to have durability against abrasion and scratches on the surface of the photoreceptor due to friction, active oxygen such as ozone generated during corona charging, surface deterioration due to nitrogen oxides, and the like.
[0005]
In order to solve the problems of mechanical and chemical durability as described above, the organic photoreceptor has a layer structure of a charge generation layer and a charge transport layer, and the charge transport layer of the surface layer has high strength and high charge. In many cases, a uniform layer hardly permeates the active gas and the thickness of the charge transport layer is set to be larger than 20 μm.
[0006]
Further, as another approach, a technique of providing a high-strength protective layer on the surface of the photoreceptor has been studied. For example, it is reported that a curable silicone resin is used as a protective layer of a photoreceptor (Patent Document 1). However, the method of thickening the charge transport layer and the method of providing a high-strength protective layer as described above have a problem that carriers generated in the charge generation layer diffuse laterally before reaching the surface, and sharpness and the like are disadvantageous. Problem. In the field of digital copiers, there is a growing demand for higher image quality, and high-resolution image formation is being studied. In this way, a good electrostatic latent image can be obtained with a layer structure or protective layer that easily causes carrier diffusion. Can not.
[0007]
In order to faithfully reproduce image information as an electrostatic latent image, it is necessary to ensure a sufficient potential contrast between the exposed and unexposed portions. This is because diffusion of carriers until the generated carriers reach the surface charge is performed. It is important to control. The latent image deterioration of a high-density image is caused by the fact that when the ratio D / μ between the diffusion constant (D) and the drift mobility (μ) of the charge transport layer increases, the effect of diffusion to the electrostatic latent image cannot be ignored, It has been reported that the latent image degradation increases as the layer thickness increases (Non-Patent Document 1).
[0008]
Further, an organic photoreceptor in which the charge transport layer is made thinner to prevent diffusion of an electrostatic latent image has already been proposed (Patent Document 2). However, when these proposed organic photoreceptors are actually formed using an electrophotographic image forming apparatus, an unclear image having a reduced image density tends to appear. This is because, when the organic photoreceptor is made thinner, the capacitance of the photosensitive layer becomes smaller, the charging potential decreases, and as a result, the developability decreases and the image density decreases. In particular, when a developer using a toner having a small particle diameter is used to obtain high image quality, the developability is reduced, the image density in reversal development is not sufficient, and a character image or a photographic image with sharpness is obtained. There is a problem that it is difficult to be performed.
[0009]
In order to recover this decrease in the developing property, it is effective to apply an increased amount of charge per unit area to the thinned organic photoreceptor to increase the electric field intensity per unit thickness of the photoreceptor. . However, when the electric field intensity per unit film thickness of the photoreceptor is increased, image defects such as black spots and white spots on the contrary tend to increase in reversal development. That is, black spots are likely to occur due to injection of free carriers from the conductive support. That is, when the electric field intensity per unit film thickness of the photoreceptor is increased, the injection of charges irrelevant to the image from the conductive support constituting the photoreceptor increases with the increase in the electric field intensity of the photoreceptor. Image defects are likely to occur. As a method for improving the black spots, a wide range of measures have been taken to prevent the injection of free carriers by providing an intermediate layer or anodizing the surface of the conductive substrate to form an insulating layer. For example, there has been proposed a photoreceptor in which the thickness of a photosensitive layer is reduced, and an intermediate layer contains titanium oxide particles (Patent Document 3). However, in the reversal development in which the electric field intensity is increased, the above-mentioned method cannot sufficiently prevent black spots.
[0010]
Furthermore, if the amount of electric charge per unit area increases in order to increase the electric field intensity per unit film thickness of the photoconductor, image unevenness (hereinafter referred to as environmental memory) due to environmental fluctuations in temperature and humidity tends to occur. is there.
[0011]
On the other hand, when the surface charge of the photoreceptor is increased and the electric field intensity per unit film thickness is increased, the adhesion of foreign substances to the photoreceptor surface becomes stronger, and the opposite to the above-mentioned black spots, which is referred to as white drop in reversal development. An image defect is generated, and the sharpness is easily reduced. It is considered that the white drop is caused by filming of the fine toner or the like on the surface of the photoreceptor and the surface charge does not disappear in the exposed portion. When the surface charge of the photoreceptor increases, the Coulomb force between the toner and the photoreceptor increases. It is considered that the cleaning property is reduced with an increase in the whiteness, and white spots are likely to occur. In addition, when a small particle size toner is used, the occurrence of white spots tends to occur as the surface area of the toner increases.
[0012]
In order to improve the cleaning property of the toner, a technique for incorporating fluorine resin particles on the surface of the photoreceptor has been disclosed in patents and the like (Patent Document 4). However, a latent image is formed on a photoreceptor having a surface containing fluorine-based resin particles under a charging condition with an increased electric field strength, and an image blur is likely to occur in a developed toner image. In particular, when a toner having a small particle size is used, image blur is remarkable.
[0013]
[Patent Document 1]
JP-A-6-118681
[Patent Document 2]
JP-A-5-119503
[Patent Document 3]
JP-A-2002-196522
[Patent Document 4]
JP-A-63-65449
[Non-patent document 1]
The Imaging Society of Japan, Vol. 38, No. 4, page 296
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to reduce the diffusion of carriers, to form an accurate electrostatic latent image, and to reduce image defects such as black spots, white spots, environmental memory, and image blur. The object of the present invention is to provide an organic photoreceptor capable of preventing the occurrence of an image and ensuring high quality image quality with good image density, sharpness and gradation, and an image forming method, an image forming apparatus and a process cartridge. . More specifically, image defects such as black spots, white spots, environmental memory, and image blur that are likely to occur when an electrostatic latent image in which the charge transport layer is thinned and carrier diffusion is reduced are visualized with toner. And an image forming method, an image forming apparatus, and a process using the organic photoreceptor. It is to provide a cartridge.
[0019]
[Means for Solving the Problems]
As a result of repeated investigations on the above problems, we have improved the sharpness using an organic photoreceptor and performed reversal development at high electric field strength (reversal development under the condition of increasing the amount of charge per unit area of the photoreceptor). In order to prevent the occurrence of image defects such as black spots, white spots, environmental memory, and image blur that are likely to occur, the organic photoreceptor has a charge generation layer and a charge transport layer, and the charge transport layer forms a surface layer. It is necessary to reduce the thickness of the layer so as to prevent carrier diffusion and to prevent image defects such as black spots, white spots, environmental memory, and image blur that are likely to occur at high electric field strength. For that purpose, in order to effectively prevent the injection of free carriers from the conductive substrate, which is facilitated by the thinning of the charge transport layer, even if the charge generation layer is made thicker, the sensitivity is high, and the temperature of the sensitivity and charging characteristics is high. It has been discovered that it is important to use a charge generating substance having low humidity dependency and to reduce the surface energy of the photoreceptor to reduce the adhesion of foreign matter that causes white spots, and completed the present invention. .
[0020]
That is, the present invention has the following configuration to prevent the occurrence of image defects such as black spots, white spots, environmental memory, and image blur, and to provide high image quality with excellent image density, sharpness, and gradation. Can be obtained. That is, the object of the present invention is achieved by having the following configuration.
[0021]
1. A charge generation layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms on a conductive support, and at least one layer having a total film thickness of 5 to 15 μm on the charge generation layer An organic photoreceptor having the above laminated structure, wherein the uppermost layer contains fluorine resin particles.
[0022]
2. An intermediate layer containing inorganic particles on a conductive support, a charge generation layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms, and a total film thickness on the charge generation layer Has a laminated structure of at least one layer having a thickness of 5 to 15 μm, and an uppermost layer contains fluorine resin particles.
[0023]
3. 3. The organic photoconductor according to item 2, wherein the intermediate layer is a semiconductive or insulating layer having a volume resistance of 10 ⁸ Ω · cm or more.
[0024]
4. An image forming method, wherein an electrophotographic image is formed using the organic photoreceptor according to any one of the above items 1 to 3.
[0025]
5. An image forming apparatus for forming an electrophotographic image by using the image forming method according to the above item 4.
[0026]
6. The organic photoreceptor according to any one of the above 1 to 3, a charging unit for uniformly charging the organic photoreceptor, a latent image forming unit for forming an electrostatic latent image on the charged organic photoreceptor, Developing means for visualizing the electrostatic latent image on the organic photoreceptor, transfer means for transferring the toner image visualized on the organic photoreceptor onto a transfer material, and electric charge on the organic photoreceptor after the transfer And at least one of cleaning means for removing residual toner on the organic photoreceptor after transfer is integrally supported, and can be detachably attached to the image forming apparatus main body. Characteristic process cartridge.
[0027]
Hereinafter, the present invention will be described in detail.
The organic photoreceptor used in the present invention has a charge generating layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms on a conductive support, and a total film thickness on the charge generating layer. Has a laminated structure of at least one layer of 5 to 15 μm, and the uppermost layer contains fluorine resin particles.
[0028]
Further, the organic photoreceptor used in the present invention is an intermediate layer containing inorganic particles on a conductive support, and a charge generating layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms. And a layered structure of at least one layer having a total film thickness of 5 to 15 μm on the charge generation layer, and the uppermost layer contains fluorine resin particles.
[0029]
In the present invention, since the organic photoreceptor has the above-described configuration, even when image formation is performed by reversal development under a high electric field strength, black spots are less likely to occur, and occurrence of white spots is also prevented. Blur can be prevented, and an electrophotographic image with improved sharpness can be obtained for both the character image and the halftone image.
[0030]
Hereinafter, the organic photoreceptor used in the present invention will be described.
The charge generating substance used in the organic photoreceptor of the present invention is characterized by containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms. In the present invention, the titanyl phthalocyanine compound has a titanyl (O = Ti) group at the center of the phthalocyanine residue represented by the general formula (1).
[0031]
Embedded image

[0032]
In the general formula (1), X ^{1 to} X ⁴ represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and n, m, l, and k represent an integer of 0 to 4.
[0033]
The diol having a hydroxyl group at each of two adjacent carbon atoms of the present invention (hereinafter, also simply referred to as adjacent diol) is a diol having one hydroxyl group at each adjacent carbon atom of an aliphatic hydrocarbon, for example, ethylene glycol, Examples thereof include 1,2-propanediol, 1,2-butanediol, 2,3-butanediol, 1,2-hexanediol, and glycerin. Preferable examples include optically active diols represented by the general formulas (2) and (3) in which two adjacent carbon atoms are each asymmetric carbon.
[0034]
Embedded image

[0035]
(In the general formulas (2) and (3), R ₃ , R ₄ , R ₅ , and R ₆ each independently represent an alkyl group.)
As the alkyl group for R ₃ , R ₄ , R ₅ , and R ₆ , a methyl, ethyl, or propyl group is preferable. That is, when the alkyl group of R _{3 to} R _{6 is} an alkyl group having a relatively small number of carbon atoms, an adduct with titanyl phthalocyanine is easily formed. Among them, a titanyl phthalocyanine adduct using at least one of (2R, 3R) -2,3-butanediol and (2S, 3S) -2,3-butanediol is most preferable. The structure of the titanyl phthalocyanine adduct can be represented, for example, by an adduct with (2R, 3R) -2,3-butanediol, as shown below. It is presumed to be an adduct compound formed by the dehydration condensation of
[0036]
Embedded image

[0037]
The titanyl phthalocyanine adduct of the present invention can be synthesized by reacting the above adjacent diol and titanyl phthalocyanine in various solvents at room temperature or under heating. The raw material titanyl phthalocyanine can be obtained from phthalonitrile and titanium tetrachloride, from diiminoisoindoline and alkoxytitanium, from phthalonitrile, urea, and alkoxytitanium. Although it is also possible to use, in particular, high-purity titanyl phthalocyanine having a low chlorine content and obtained from diiminoisoindoline and alkoxytitanium is preferable. The titanyl phthalocyanine is preferably made amorphous by a method such as acid paste treatment and then reacted with an adjacent diol. In order to obtain the titanyl phthalocyanine adduct of the present invention, it is preferable to add 0.5 to 2.0 molar equivalents of the adjacent diol to the titanyl phthalocyanine and react them. No more than 1.0 molar equivalent of adjacent diol is required. This is presumably because the titanyl phthalocyanine adduct of the present invention can maintain a high sensitivity and high performance state as a charge generating substance even in a mixed crystal state of adjacent diol addition titanyl phthalocyanine and no adjacent diol addition titanyl phthalocyanine.
[0038]
The reaction between titanyl phthalocyanine and diol can be performed under a wide range of temperature conditions, and the reaction temperature is preferably in the range of 25 to 300C, more preferably in the range of 50 to 150C.
[0039]
As the reaction solvent, various organic solvents can be used, for example, aromatic organic solvents such as toluene, nitrobenzene, dichlorobenzene, trichlorobenzene, and α-chloronaphthalene; Organic solvents, ether organic solvents such as tetrahydrofuran and dimethyl cellosolve, ester organic solvents such as butyl acetate, aprotic polar organic solvents such as dimethylformamide and dimethyl sulfoxide, halogen organic solvents such as trichloroethane, butanol, octanol, dodecanol And the like.
[0040]
In the crystal form or the titanyl phthalocyanine adduct of the present invention, in the Cu-Kα characteristic X-ray diffraction spectrum, a clear diffraction peak at a Bragg angle (2θ) of 8.0 to 8.8 (can be clearly distinguished from the background) (Peak). In addition, it may have a clear peak at 9.5 °, 24.7 °, 25.1 °, 26.5 °, or the like. The titanyl phthalocyanine adduct of the present invention having a crystal structure having a clear diffraction peak at a Bragg angle (2θ) of 8.0 to 8.8 has excellent sensitivity characteristics and image unevenness due to environmental memory, black spots, image blur, and the like. In addition, it has characteristics with few image defects.
[0041]
The organic photoreceptor of the present invention comprises, on a conductive support, a charge generation layer containing a charge generation substance of an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms, and a charge generation layer thereon. It has a structure of a negatively charged organic photoreceptor having a charge transporting layer containing a transporting substance and having a total film thickness of 5 to 15 μm (a negative electrostatic latent image is formed). The charge generation material of the layer is mainly an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms, so that electrons generated in the charge generation layer travel a relatively long distance. It can conduct to the conductive substrate. For this reason, even if the charge generation layer is formed to have a relatively large thickness, an increase in the residual potential due to trapping of electrons is prevented. The thickness of the charge generation layer is preferably from 0.3 to 2.0 μm. Further, if the charge generation layer has a film thickness in the above range, the pigment concentration can be sufficiently increased, so that a single wavelength of image exposure light, laser light, LED light or the like generally used in digital image formation can be used. Moire or the like due to light irradiation can also be prevented. In addition, an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms has a remarkable effect of preventing free carrier injection from a conductive substrate, and significantly improves black spots in reversal development. I do.
[0042]
When the thickness of the charge generation layer is less than 0.3 μm, it is difficult to sufficiently contain the pigment concentration, so that the exposure potential is insufficiently reduced to lower the image density or the effect of preventing laser light interference from being reduced. It's easy to do. On the other hand, if it is larger than 2.0 μm, the trap density of charge carriers in the charge generation layer tends to increase, and image unevenness and image blur of the environmental memory tend to occur. The preferred thickness of the charge generation layer is 0.3 to 1.0 μm.
[0043]
On the other hand, the charge generation layer has a laminated structure of at least one layer, the total thickness thereof is 5 to 15 μm, and the uppermost layer contains fluorine resin particles. That is, the above-mentioned adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms also has a total film thickness of 5 to 15 μm on the charge generation layer containing the charge generation substance and the uppermost layer is made of fluorine. By providing a layer containing the system resin particles, black spots are hardly generated and white spots are prevented from being generated, and both a character image and a halftone image can obtain an electrophotographic image with improved sharpness. I can do it.
[0044]
The layer structure having a total thickness of 5 to 15 μm on the charge generation layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer contains fluorine resin particles. The layer structure composed of multiple charge transport layers with a total film thickness of 5 to 15 μm reduces diffusion of charge carriers generated in the charge generation layer and reproduces a latent image composed of fine dots with sufficient potential contrast can do. If the total thickness is less than 5 μm, the charging potential tends to be insufficient. If the total thickness exceeds 15 μm, the diffusion of the charge carriers increases, and the sharpness is not sufficiently improved. In particular, when the total thickness of the charge transport layer is in the range of 8 to 14 μm, the effect of improving sharpness is more remarkable.
[0045]
The fluorine-based resin particles contained in the uppermost charge transport layer means resin particles containing fluorine atoms, for example, ethylene tetrafluoride resin, ethylene trifluoride chloride resin, hexafluoroethylene propylene resin, It is preferable to appropriately select one or more of vinyl fluoride resins, vinylidene fluoride resins, ethylene difluoride ethylene chloride resins and copolymers thereof, and in particular, ethylene tetrafluoride resins and fluorocarbon resins. Vinylidene fluoride resins are preferred. The molecular weight and particle size of the fluororesin particles can be appropriately selected and are not particularly limited.
[0046]
The charge transport layer of the uppermost layer preferably has a structure containing fluorine-based resin particles in the binder resin, and the ratio of the fluorine-based resin particles is also affected by the particle diameter of the particles. It is preferably 50% by mass, more preferably 5 to 40% by mass. Further, the uppermost layer preferably contains a charge transporting substance.
[0047]
Additives such as coupling agents and antioxidants may be added to the uppermost layer of the present invention for the purpose of improving dispersibility, binding properties and weather resistance.
[0048]
Examples of the method for dispersing the fluorine-based resin particles in the uppermost layer include a method such as a homogenizer, a ball mill, a sand mill, a roll mill, and ultrasonic waves. There is no particular limitation as long as the particles can be dispersed to the primary particle size.
[0049]
In addition, various surfactants such as comb-type graft polymers may be appropriately mixed as a dispersing aid for the fluororesin particles.
[0050]
The thickness of the uppermost layer is preferably 0.1 to 4 μm. If the thickness is less than 0.1 μm, the surface hardness and strength are not sufficient, and the durability tends to decrease. If the thickness exceeds 4 μm, the contrast potential formed by a latent image during development tends to deteriorate. More preferably, it is 0.2 to 3.0 μm.
[0051]
The uppermost layer preferably has a low surface energy in order to satisfy the cleaning property and the stain resistance, and the low surface energy measured by the contact angle of water is preferably 90 degrees or more. If the angle is less than 90 degrees, a charge product, toner, or falling off from paper is likely to adhere to the surface due to repeated use in an electrophotographic process, and a latent image is likely to be degraded (image deletion) due to poor cleaning or reduced surface resistance. It is more preferably at least 95 degrees.
[0052]
Blocking of free carriers (electrons and holes entering from the conductive support) from the conductive support by having a structure in which inorganic particles are contained in the binder resin of the intermediate layer of the organic photoreceptor used in the present invention. The electrophotographic image having high gradation and good sharpness can be obtained by improving the properties, preventing the occurrence of black spots and fogging, and increasing the developability.
[0053]
Examples of the binder resin for the intermediate layer of the present invention include polyamide resins, ethylene copolymer resins such as ELVAX4260 (manufactured by DuPont), polyurethane resins such as NL2532 (manufactured by Mitsui Chemicals), NL2249E (manufactured by Mitsui Chemicals), and modified polyolefins. Resins, for example, Supercron (manufactured by Nippon Paper Industries), GS2000 (Lead City Co., Ltd.), and the like. Of these, alcohol-soluble polyamides are particularly preferred. Alcohol-soluble polyamides have excellent solvent solubility and good dispersion stability of inorganic particles, and the synergistic effect of the binder and the inorganic particles improves the blocking properties of the free carrier and prevents image defects such as black spots. Has a remarkable effect.
[0054]
Examples of the alcohol-soluble polyamide include an alkoxymethylated nylon and a copolymerized nylon. For example, methoxymethylated nylon and nylon 6/66/610/12 copolymer are commercially available.
[0055]
The number average molecular weight of the polyamide resin is preferably 5,000 to 80,000, more preferably 10,000 to 60,000. When the number average molecular weight is 5,000 or less, the uniformity of the thickness of the intermediate layer is deteriorated, and the effect of the present invention is hardly exerted. On the other hand, if it is larger than 80,000, the solvent solubility of the resin tends to decrease, an aggregated resin is easily generated in the intermediate layer, and image defects such as black spots are easily generated.
[0056]
As a solvent for dissolving the polyamide resin of the present invention to prepare a coating solution, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol and sec-butanol are used. Preferably, it is excellent in solubility of polyamide and applicability of the prepared coating solution. These solvents are used in an amount of 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% by mass, based on the whole solvent. Examples of the co-solvent which can obtain a preferable effect when used in combination with the above-mentioned solvent include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, tetrahydrofuran and the like.
[0057]
The inorganic particles used in the intermediate layer of the present invention include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), zirconium oxide, cerium oxide, iron oxide, aluminum oxide, tungsten oxide, bismuth oxide, and the like. Metal oxides, silicon carbide, metal carbides such as titanium carbide, strontium titanate, calcium titanate, titanates such as barium titanate, carbonates such as calcium carbonate, metal nitrides such as aluminum nitride, barium sulfate, Sulfates such as copper sulfate and zinc sulfate are exemplified. It is preferable to coat the surface of these inorganic particles with another metal oxide. For example, it is preferable to coat the surface of the inorganic particles with silica, alumina, zirconia, tin oxide, tin oxide doped with antimony oxide, or the like, coat a hydroxyl group present on the surface of the inorganic particles, and improve moisture resistance. . The content of the particles in the intermediate layer is preferably from 10% to 90% by volume, and more preferably from 25% to 75%.
[0058]
The number average primary particle diameter of the inorganic particles is preferably from 10 to 400 nm. The number average primary particle diameter is a value measured as an average diameter in Feret direction by observing 100 inorganic particles as primary particles by magnifying the inorganic particles by 10,000 times by transmission electron microscope observation, and randomly observing the particles as primary particles. It is.
[0059]
When such an inorganic particle is contained in the intermediate layer, moire caused by laser light, which is one of image defects, is reduced, and free carriers (electrons and holes entering from a conductive support or the like) in the intermediate layer are blocked. Can be enhanced.
[0060]
The inorganic particles used in the present invention are preferably N-type semiconductive particles. The N-type semiconductive particles mean particles whose main charge carriers are electrons. That is, since the main charge carriers are electrons, the intermediate layer containing the N-type semiconductive particles in the insulating binder efficiently blocks hole injection from the substrate, Has a property of low blocking property.
[0061]
Specific examples of the N-type semiconductive particles include inorganic particles such as titanium oxide (TiO ₂ ), zinc oxide (ZnO), and tin oxide (SnO ₂ ). In the present invention, titanium oxide is particularly preferable. Used.
[0062]
The average particle size of the N-type semiconductive particles is preferably in the range of 10 nm to 400 nm in number average primary particle size, and more preferably 15 nm to 200 nm. If it is less than 10 nm, the effect of preventing the occurrence of moire by the intermediate layer is small. On the other hand, when it is larger than 400 nm, sedimentation of the N-type semiconductive particles in the coating liquid for the intermediate layer tends to occur, and as a result, the uniform dispersibility of the N-type semiconductive particles in the intermediate layer is poor, and black spots increase. Cheap. An intermediate layer coating solution using N-type semiconductive particles having a number average primary particle diameter in the above range has good dispersion stability, and an intermediate layer formed from such a coating solution has a black spot prevention function. In addition, it has good environmental characteristics and has cracking resistance.
[0063]
The shape of the N-type semiconductor particles has dendritic, needle-like and granular shapes, and the N-type semiconductor particles having such a shape include, for example, titanium oxide particles, anatase type, and There are a rutile type, an amorphous type, and the like, and any crystal type may be used, or a mixture of two or more types may be used. Among them, the rutile type and granular type are the best.
[0064]
One of the surface treatments performed on the N-type semiconductor particles includes performing a plurality of surface treatments, and in the plurality of surface treatments, the last surface treatment is performed using a reactive organosilicon compound. Is what you do. Further, among the plurality of surface treatments, at least one surface treatment performs at least one or more surface treatments selected from alumina, silica, and zirconia, and finally, a surface treatment using a reactive organosilicon compound. Is preferably performed.
[0065]
The alumina treatment, the silica treatment, and the zirconia treatment refer to a treatment for depositing alumina, silica, or zirconia on the surface of the N-type semiconductive particles.Alumina, silica, and zirconia deposited on these surfaces have alumina, silica, Also included are hydrates of zirconia. Further, the surface treatment of the reactive organosilicon compound means to use the reactive organosilicon compound in the treatment solution.
[0066]
As described above, by performing the surface treatment of the N-type semiconductor particles such as the titanium oxide particles at least twice, the surface of the N-type semiconductor particles is uniformly coated (treated), and the surface treatment is performed. When the N-type semiconductive particles are used in the intermediate layer, a good photoreceptor which has good dispersibility of N-type semiconductive particles such as titanium oxide particles in the intermediate layer and does not generate image defects such as black spots. You can get it.
[0067]
Further, it is particularly preferable that the surface treatment is performed a plurality of times using alumina and silica, and then the surface treatment is performed using a reactive organosilicon compound.
[0068]
The above-described treatment of alumina and silica may be performed simultaneously, but it is particularly preferable to perform the silica treatment first, and then perform the alumina treatment. In the case where alumina and silica are respectively treated, the amount of alumina and silica to be treated is preferably larger than that of alumina.
[0069]
The surface treatment of the N-type semiconductive particles such as titanium oxide with a metal oxide such as alumina, silica, and zirconia can be performed by a wet method. For example, N-type semiconductive particles that have been subjected to silica or alumina surface treatment can be prepared as follows.
[0070]
When titanium oxide particles are used as the N-type semiconductor particles, titanium oxide particles (number average primary particle diameter: 50 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry, and the aqueous slurry A silicate or a water-soluble aluminum compound is added. Thereafter, neutralization is performed by adding an alkali or an acid to deposit silica or alumina on the surface of the titanium oxide particles. Subsequently, filtration, washing and drying are performed to obtain a target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.
[0071]
The amount of the metal oxide used in the surface treatment is 0.1 to 50 parts by mass with respect to 100 parts by mass of the N-type semiconductive particles such as titanium oxide particles in the amount charged during the surface treatment. More preferably, 1 to 10 parts by mass of a metal oxide is used. In the case of using the above alumina and silica, for example, in the case of titanium oxide particles, it is preferable to use 1 to 10 parts by mass with respect to 100 parts by mass of titanium oxide particles, and it is preferable that the amount of silica is larger than that of alumina. .
[0072]
The surface treatment with the reactive organosilicon compound performed next to the surface treatment with the metal oxide is preferably performed by the following wet method.
[0073]
That is, the titanium oxide treated with the metal oxide is added to a liquid in which the reactive organic silicon compound is dissolved or suspended in an organic solvent or water, and the liquid is subjected to media dispersion using ceramic beads. Is preferred. Next, the dispersion liquid after the dispersion of the medium is filtered and then dried under reduced pressure while performing a heat treatment to obtain titanium oxide particles whose surface is coated with an organosilicon compound. The reactive organic silicon compound may be added to a suspension in which titanium oxide is dispersed in an organic solvent or water.
[0074]
In the present invention, the fact that the surface of the titanium oxide particles is coated with the reactive organosilicon compound may be determined by photoelectron spectroscopy (ESCA), Auger electron spectroscopy (Auger), secondary ion mass spectroscopy (SIMS), or diffuse reflection. This is confirmed by combining surface analysis techniques such as FI-IR.
[0075]
The amount of the reactive organosilicon compound used for the surface treatment is, with respect to 100 parts by mass of the titanium oxide treated with the metal oxide in the charged amount at the time of the surface treatment, the reactive organosilicon compound is 0.1 to 0.1 parts by mass. 50 parts by mass, more preferably 1 to 10 parts by mass. If the surface treatment amount is less than the above range, the surface treatment effect is not sufficiently provided, and the dispersibility and the like of the titanium oxide particles in the intermediate layer deteriorate. Further, when the value exceeds the above range, the electric performance is deteriorated, and as a result, the residual potential increases and the charging potential decreases.
[0076]
Examples of the reactive organosilicon compound used in the present invention include a compound represented by the following general formula (4). If the compound has a condensation reaction with a reactive group such as a hydroxyl group on the surface of titanium oxide, the following compound may be used. It is not limited to.
[0077]
General formula (4)
(R) _n -Si- (X) _4-n
(In the formula, Si represents a silicon atom, R represents an organic group in which carbon is directly bonded to the silicon atom, X represents a hydrolyzable group, and n represents an integer of 0 to 3.)
In the organosilicon compound represented by the general formula (4), examples of the organic group in which carbon represented by R is directly bonded to silicon include alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and dodecyl. Groups, aryl groups such as phenyl, tolyl, naphthyl, and biphenyl; epoxy-containing groups such as γ-glycidoxypropyl and β- (3,4-epoxycyclohexyl) ethyl; γ-acryloxypropyl; γ-methacryloxypropyl A (meth) acryloyl group, a hydroxyl group such as γ-hydroxypropyl and 2,3-dihydroxypropyloxypropyl, a vinyl group such as vinyl and propenyl, a mercapto group such as γ-mercaptopropyl, a γ-aminopropyl, An amino-containing group such as N-β (aminoethyl) -γ-aminopropyl, γ-chloropropyl, , 1,1-tri fluoroalkyl propyl, nonafluorohexyl, halogen-containing groups such as perfluorooctylethyl, other nitro, and cyano-substituted alkyl group. Examples of the hydrolyzable group for X include an alkoxy group such as methoxy and ethoxy, a halogen group, and an acyloxy group.
[0078]
The organosilicon compound represented by the general formula (4) may be used alone or in combination of two or more.
[0079]
When n is 2 or more in the specific compound of the organosilicon compound represented by the general formula (4), a plurality of Rs may be the same or different. Similarly, when n is 2 or less, a plurality of Xs may be the same or different. When two or more organosilicon compounds represented by the general formula (4) are used, R and X may be the same or different between the respective compounds.
[0080]
A preferred reactive organosilicon compound used for the final surface treatment is a polysiloxane compound. The polysiloxane compound having a molecular weight of 1,000 to 20,000 is generally easily available, and has a good black spot prevention function.
[0081]
In particular, when methyl hydrogen polysiloxane is used for the final surface treatment, a good effect can be obtained.
[0082]
Another one of the surface treatments of the titanium oxide of the present invention is titanium oxide particles that have been surface-treated with an organosilicon compound having a fluorine atom. The surface treatment with the organosilicon compound having a fluorine atom is preferably performed by the above-mentioned wet method.
[0083]
That is, the organosilicon compound having a fluorine atom is dissolved or suspended in an organic solvent or water, untreated titanium oxide is added thereto, such a solution is dispersed in a medium, filtered, and heated. After the application, it is dried, and the surface of the titanium oxide is coated with an organosilicon compound having a fluorine atom. The organic silicon compound having a fluorine atom may be added to a suspension in which titanium oxide is dispersed in an organic solvent or water.
[0084]
The fact that the surface of the titanium oxide is coated with the organosilicon compound having a fluorine atom is determined by photoelectron spectroscopy (ESCA), Auger electron spectroscopy (Auger), secondary ion mass spectroscopy (SIMS), or diffuse reflection FI. -It can be confirmed compositely using a surface analyzer such as IR.
[0085]
Examples of the organosilicon compound having a fluorine atom used in the present invention include 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxy Silane, methyl-3,3,3-trifluoropropyldichlorosilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3,3,4,4,5,5,6,6,6-nonafluoro Hexylmethyldichlorosilane and the like.
[0086]
The amount of the N-type semiconductive particles dispersed in the polyamide resin is, for example, in the case of surface-treated titanium oxide, 10 to 10,000 parts by mass, preferably 50 to 1,000 parts by mass with respect to 100 parts by mass of the binder resin. 000 parts by mass. By using the surface-treated titanium oxide in this range, the dispersibility of the titanium oxide can be kept good, and a good intermediate layer free of black spots can be formed.
[0087]
Further, the intermediate layer of the present invention is substantially an insulating layer. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ to 10 ¹⁵ Ω · cm. The volume resistance of the intermediate layer of the present invention is preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, more preferably 2 × 10 ⁹ to 1 × 10 ¹³ Ω · cm. Volume resistance can be measured as follows.
[0088]
Measurement conditions: according to JIS: C2318-1975.
Measuring device: Mitsubishi Yuka's Hiresta IP
Measurement conditions: Measurement probe HRS
Applied voltage: 500V
Measurement environment: 30 ± 2 ° C, 80 ± 5RH%
If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer is reduced, the occurrence of black spots is increased, and the potential holding property of the electrophotographic photoreceptor is deteriorated, so that good image quality cannot be obtained. On the other hand, if it is larger than 10 ¹⁵ Ω · cm, the residual potential tends to increase in repeated image formation, and good image quality cannot be obtained.
[0089]
The intermediate layer coating solution prepared to form the intermediate layer of the present invention is composed of surface-treated N-type semiconductive particles such as the surface-treated titanium oxide, a binder resin, and a dispersion solvent. A solvent similar to the solvent of the polyamide resin described above is appropriately used.
[0090]
By dispersing and containing the fine particles as described above in the polyamide resin of the present invention, the electrophotographic properties, particularly the humidity dependence of the potential upon repeated use, and the improvement effects of black spots, image unevenness, image blur, etc. are increased. Can be done.
[0091]
In addition, the organic photoreceptor used in the present invention can significantly improve sharpness by adopting the above-described configuration, and easily occurs when the charge transport layer is thinned. It is possible to provide an organic photoreceptor that prevents image defects such as memory and image blur and has stable potential performance.
[0092]
Hereinafter, the configuration of the organic photoconductor applied to the present invention other than the above will be described.
In the present invention, the organic photoreceptor refers to an electrophotographic photoreceptor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function, which are indispensable for the configuration of the electrophotographic photoreceptor. And all known organic photoconductors such as a photoconductor composed of an organic charge-generating substance or an organic charge-transport substance, and a photoconductor composed of a polymer complex having a charge generation function and a charge transport function.
[0093]
The charge transport layer of the present invention means a layer having a function of transporting charge carriers generated in the charge generation layer by light exposure to the surface of the organic photoreceptor. It can be confirmed by laminating the layer and the charge transport layer on a conductive support and detecting photoconductivity.
[0094]
The layer constitution of the organic photoreceptor of the present invention basically comprises a photosensitive layer of a charge generation layer and a charge transport layer on a conductive support. Most preferably, the photosensitive layer comprises a charge generation layer and a charge transport layer.
[0095]
Hereinafter, a specific configuration of the photoconductor used in the present invention will be described.
Conductive Support A sheet-like or cylindrical conductive support is used as the conductive support used in the photoreceptor of the present invention.
[0096]
The cylindrical conductive support of the present invention means a cylindrical support required to be able to form an image endlessly by rotation, and has a straightness of 0.1 mm or less and a runout of 0.1 mm or less. Certain conductive supports are preferred. Exceeding the ranges of straightness and runout makes it difficult to form a good image.
[0097]
As a material for the conductive support, a metal drum such as aluminum or nickel, a plastic drum on which aluminum, tin oxide, indium oxide, or the like is deposited, or a paper or plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature.
[0098]
The conductive support used in the present invention may have a surface on which a sealed alumite film is formed. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, and sulfamic acid. Anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodic oxidation treatment in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average thickness of the anodic oxide coating is usually 20 μm or less, particularly preferably 10 μm or less.
[0099]
Intermediate layer In the present invention, the above-mentioned intermediate layer having a barrier function is provided between the conductive support and the photosensitive layer. The thickness of the intermediate layer of the present invention is preferably from 0.2 to 10 μm, most preferably from 0.5 to 5 μm.
[0100]
Photosensitive Layer Charge Generating Layer In the organic photoreceptor of the present invention, the above-mentioned titanyl phthalocyanine adduct pigment is used as a charge generating substance. Can be.
[0101]
In the case where a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder. No. The ratio between the binder resin and the charge generating substance is preferably from 20 to 600 parts by mass per 100 parts by mass of the binder resin. By using these resins, an increase in residual potential due to repeated use can be minimized. The thickness of the charge generation layer is preferably 0.3 μm to 2 μm.
[0102]
Charge Transport Layer As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer preferably contains fluorine-based resin particles.
[0103]
The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses the CTM and forms a film. As other substances, additives such as the above-mentioned fluororesin particles and antioxidants may be contained as necessary.
[0104]
As the charge transporting substance (CTM), a known hole transporting (P-type) charge transporting substance (CTM) is preferably used. For example, triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, butadiene compounds and the like can be used. These charge transporting substances are usually dissolved in a suitable binder resin to form a layer. Among these, the CTM that can minimize the increase in residual potential due to repeated use has a high mobility and a characteristic that the ionization potential difference with the CGM to be combined is 0.5 (eV) or less, and is preferably 0. .30 (eV) or less.
[0105]
The ionization potential of CGM and CTM is measured with a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).
[0106]
The binder resin used for the charge transport layer (CTL) does not matter whether it is a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, polymer organic semiconductors such as poly-N-vinyl carbazole may be used. Among them, a polycarbonate resin having a small water absorption, good CTM dispersibility and good electrophotographic properties is most preferable.
[0107]
The ratio of the binder resin to the charge transporting material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.
[0108]
Solvents or dispersion media used for forming layers such as an intermediate layer, a charge generation layer, and a charge transport layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, and acetone. , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolan, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although the present invention is not limited to these, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone and the like are preferably used. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.
[0109]
Next, as a coating processing method for manufacturing an organic photoreceptor, a coating processing method such as dip coating, spray coating, circular amount control type coating or the like is used. It is preferable to use a coating processing method such as spray coating or circular amount control type (a typical example is a circular slide hopper type) coating so as not to dissolve as much as possible and to achieve uniform coating processing. It is most preferable that the protective layer be formed by the above-mentioned circular amount-regulating coating method. The circular amount control type coating is described in detail in, for example, JP-A-58-189061.
[0110]
Next, an image forming apparatus using the organic photoreceptor of the present invention will be described.
The image forming apparatus 1 shown in FIG. 6 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. I have.
[0111]
An automatic document feeder for automatically transporting a document is provided above the image reading unit A. The document placed on the document table 11 is separated and transported one by one by a document transport roller 12, and is moved to a reading position 13a. Image is read. The document for which reading of the document has been completed is discharged onto the document discharge tray 14 by the document conveying roller 12.
[0112]
On the other hand, when the image of the original placed on the platen glass 13 is read at a speed v of a first mirror unit 15 including an illumination lamp and a first mirror constituting a scanning optical system, and a V-shaped second image is read. Reading is performed by moving the second mirror unit 16 including the second mirror and the third mirror in the same direction at the speed v / 2.
[0113]
The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The linear optical image formed on the image sensor CCD is sequentially subjected to A / D conversion after being photoelectrically converted into an electric signal (luminance signal), and subjected to processing such as density conversion and filter processing in an image processing unit B. After that, the image data is temporarily stored in the memory.
[0114]
In the image forming section C, a drum-shaped photosensitive member 21 serving as an image carrier, a charging unit (charging step) 22 for charging the photosensitive member 21, and a surface potential of the charged photosensitive member Detecting means 220, a developing means (developing step) 23, a transfer / conveying belt device 45 as a transferring means (transfer step), a cleaning device (cleaning step) 26 for the photoreceptor 21, and a light removing means (optical charge) A PCL (precharge lamp) 27 as a generation step) is arranged in the order of operation. On the downstream side of the developing unit 23, there is provided a reflection density detecting unit 222 for measuring the reflection density of the patch image developed on the photoconductor 21. The photoreceptor 21 uses the organic photoreceptor of the present invention and is driven and rotated clockwise in the drawing.
[0115]
After the rotating photoconductor 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by the exposure optical system 30 as an image exposure unit (image exposure step). Exposure is performed. The exposure optical system 30 serving as an image exposure means as a writing means uses a laser diode (not shown) as a light emitting light source, and the optical path is bent by a reflection mirror 32 via a rotating polygon mirror 31, an fθ lens 34, and a cylindrical lens 35, and main scanning is performed. The image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by the rotation (sub-scan) of the photoconductor 21. In one example of the present embodiment, a character portion is exposed to form an electrostatic latent image.
[0116]
In the image forming method of the present invention, when forming an electrostatic latent image on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2 × 10 ⁻⁹ m ² or less. Even if such a small-diameter beam exposure is performed, the organic photoreceptor of the present invention can faithfully form an image corresponding to the spot area. A more preferred spot area is 0.01 × 10 ⁻⁹ to 1 × 10 ⁻⁹ m ² . As a result, at 400 dpi (dpi: the number of dots per 2.54 cm) or more, it is possible to achieve an extremely excellent image quality for realizing 256 gradations.
[0117]
The spot area of the exposure beam is represented by an area corresponding to a light intensity of 1 / e ² or more of the peak intensity of the light beam.
[0118]
As the exposure beam used, there are a scanning optical system using a semiconductor laser, a solid-state scanner such as an LED or a liquid crystal shutter, and the like, and the light intensity distribution also has a Gaussian distribution, a Lorentz distribution, and the like, but 1 / e of each peak intensity. ^The area up to ² is the spot area.
[0119]
The electrostatic latent image on the photoconductor 21 is subjected to reversal development by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21. The image forming method of the present invention is characterized in that a polymerized toner is used as a developer used in the developing unit. By using a polymerized toner having a uniform shape and a uniform particle size distribution together with the organic photoreceptor of the present invention, an electrophotographic image having better sharpness can be obtained.
[0120]
Here, the term “polymerized toner” refers to a toner obtained by forming a toner binder resin and forming the toner shape by polymerization of a raw material monomer of the binder resin and a subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization and emulsion polymerization and, if necessary, a subsequent step of fusing particles together.
[0121]
Since the polymerized toner is produced by uniformly dispersing the raw material monomers in an aqueous system and then polymerizing the same, a toner having a uniform particle size distribution and shape can be obtained.
[0122]
Polymerized toners are prepared by suspension polymerization or emulsion polymerization of monomers in a liquid to which an emulsion of necessary additives is added to produce fine polymerized particles. It can be produced by a method of adding and associating. A method of preparing by associating with a dispersion liquid such as a release agent and a colorant necessary for the composition of the toner at the time of association, and dispersing toner components such as a release agent and a colorant in a monomer. And then emulsion polymerization. Here, the association means that a plurality of resin particles and colorant particles are fused.
[0123]
That is, various constituent materials such as a colorant and a releasing agent as needed, a charge control agent, and a polymerization initiator are added to the polymerizable monomer. Various constituent materials are dissolved or dispersed in the polymerizable monomer. The polymerizable monomer in which the various constituent materials are dissolved or dispersed is dispersed in an aqueous medium containing a dispersion stabilizer into oil droplets having a desired size as a toner by using a homomixer or a homogenizer. Thereafter, the stirring mechanism is moved to a reaction device, which is a stirring blade described below, and heated to cause the polymerization reaction to proceed. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a toner.
[0124]
Further, as a method of producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can also be mentioned. Although this method is not particularly limited, for example, the methods described in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904 can be exemplified. That is, a method of associating a plurality of resin particles and dispersed particles of a constituent material such as a colorant, or a fine particle composed of a resin and a colorant, particularly, after dispersing these in water using an emulsifier, the critical aggregation concentration At the same time as adding the above flocculant and salting out, the formed polymer itself is heated and fused at a temperature equal to or higher than the glass transition temperature to gradually grow the particle size while forming fused particles, and the desired particle size is obtained. When a large amount of water is added, the particle size growth is stopped by adding a large amount of water, and the shape of the particles is controlled by heating and stirring to smooth the surface of the particles. Can be formed. Here, an organic solvent infinitely soluble in water may be added together with the coagulant.
[0125]
The materials and manufacturing method for producing a toner having a uniform shape factor and the like used in the present invention, a reactor for a polymerized toner, and the like are described in detail in JP-A-2000-214629.
[0126]
In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means in which transfer papers P of different sizes are stored. A manual paper feed unit 42 for performing manual paper feed is provided on the side, and the transfer paper P selected from any of them is fed along a transport path 40 by guide rollers 43 and fed. The transfer paper P is temporarily stopped by a pair of registration rollers 44 that corrects the inclination and deviation of the transfer paper P, and then re-fed, and the conveyance path 40, the pre-transfer roller 43a, the paper supply path 46, and the entry guide The toner image on the photoreceptor 21 is guided by the plate 47 and is transferred onto the transfer paper P while being placed and transported on the transfer transport belt 454 of the transfer transport belt device 45 by the transfer pole 24 and the separation pole 25 at the transfer position Bo. Transfer sheet P is separated from the photosensitive member 21 surface, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.
[0127]
The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. The transfer paper P is passed between the fixing roller 51 and the pressure roller 52 to fix the toner by heating and pressing. The transfer paper P on which the toner image has been fixed is discharged onto the discharge tray 64.
[0128]
The above is a description of a state in which image formation is performed on one side of transfer paper. In the case of duplex copying, the discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.
[0129]
Further, the transfer paper P is transported downward by the transport mechanism 178, is switched back by the transfer paper reversing unit 179, and the rear end of the transfer paper P is transported into the double-sided copy paper supply unit 130 as the leading end. You.
[0130]
The transfer paper P is moved in the paper feeding direction by a conveyance guide 131 provided in the two-sided copy paper supply unit 130, the transfer paper P is fed again by the paper feed roller 132, and the transfer paper P is guided to the conveyance path 40. .
[0131]
Again, as described above, the transfer paper P is transported in the direction of the photoconductor 21, the toner image is transferred to the back surface of the transfer paper P, and is fixed by the fixing unit 50, and then discharged to the discharge tray 64.
[0132]
As the image forming apparatus of the present invention, the above-described photoconductor, a developing device, a cleaning device, and other components are integrally combined as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Is also good. Also, a process cartridge is formed by integrally supporting at least one of a charging device, an image exposing device, a developing device, a transfer or separation device, and a cleaning device together with a photoreceptor, as a single unit detachable from the apparatus body, It may be configured to be detachable using a guide means such as a rail of the apparatus body.
[0133]
The organic photoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copiers, laser printers, LED printers, and liquid crystal shutter printers. In addition, displays, recording, light printing, plate making and facsimile using electrophotographic technology are applied. Etc. can be widely applied.
[0134]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto. In the following description, “parts” means “parts by mass”.
[0135]
Synthesis Example 1
Synthesis of titanyl phthalocyanine-amorphous product 1,3-diiminoisoindoline; 29.2 g was dispersed in 200 ml of orthodichlorobenzene, and titanium tetra-n-butoxide; And heat for 5 hours. After cooling, the precipitated crystals are filtered, washed with chloroform, washed with a 2% aqueous hydrochloric acid solution, washed with water and methanol, and dried to obtain 26.2 g (yield 91%) of crude titanyl phthalocyanine. Then, the crude titanyl phthalocyanine is dissolved by stirring in 250 ml of concentrated sulfuric acid at 5 ° C. or less for 1 hour, and poured into 5 L of water at 20 ° C. The precipitated crystals are filtered and sufficiently washed with water to obtain 225 g of a wet paste product. Then, the wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 g of a titanyl phthalocyanine-amorphous product. (86% yield)
Synthesis Example 2
Preparation of titanyl phthalocyanine adduct CG-1 ((2R, 3R) -2,3-butanediol adduct)
200 ml of toluene and 1.8 g (0.6 molar equivalent) of (2R, 3R) -2,3-butanediol are dissolved, and 19.6 g of titanyl phthalocyanine-amorphous product is added thereto. Then, the mixture is heated to reflux with an ester tube, and reacted for 3 hours while removing generated water by azeotropic distillation with toluene. After cooling, the (2R, 3R) -2,3-butanediol adduct was filtered, washed with methanol, and dried to obtain 19.8 g of the desired adduct (CG-1). FIG. 1 shows an X-ray diffraction spectrum of CG-1.
[0136]
Synthesis Example 3
Preparation of titanyl phthalocyanine adduct CG-2 ((2R, 3R) -2,3-butanediol adduct)
200 ml of toluene and 3.7 g (1.2 molar equivalents) of (2R, 3R) -2,3-butanediol are dissolved, and 19.6 g of titanyl phthalocyanine-amorphous product is added thereto. Then, the mixture is heated to reflux with an ester tube, and reacted for 3 hours while removing generated water by azeotropic distillation with toluene. After cooling, the (2R, 3R) -2,3-butanediol adduct was filtered, washed with methanol, and dried to obtain 20.7 g of the desired adduct (CG-2). FIG. 2 shows the X-ray diffraction spectrum of CG-2.
[0137]
Synthesis Example 4
Preparation of titanyl phthalocyanine adduct CG-3 ((2S, 3S) -2,3-butanediol adduct)
200 ml of orthodichlorobenzene and 2.1 g (0.7 molar equivalent) of (2S, 3S) -2,3-butanediol are dissolved, and 19.6 g of titanyl phthalocyanine-amorphous product is added thereto. Then, the mixture is heated under reflux for 6 hours to progress the reaction. After cooling, the (2S, 3S) -2,3-butanediol adduct was filtered, washed with methanol, and dried to obtain 20.0 g of the desired adduct (CG-3). FIG. 3 shows the X-ray diffraction spectrum of CG-3.
[0138]
Preparation of Photoconductor 1 Photoconductor 1 was prepared as described below.
[0139]
The surface of a cylindrical aluminum support having a diameter of 100 mmφ and a length of 346 mm was cut to prepare a conductive support having a surface roughness Rz = 1.5 (μm).
<Intermediate layer>
The following intermediate layer dispersion was diluted twice with the same mixed solvent, allowed to stand overnight, and filtered (filter; Rigimesh 5 μm filter manufactured by Pall Corporation) to prepare an intermediate layer coating solution.
[0140]

Were mixed, and the mixture was dispersed in a batch system for 10 hours using a sand mill as a dispersing machine to prepare an intermediate layer dispersion.
[0141]
Using the above coating solution, coating was performed on the support so as to have a dry film thickness of 1.0 μm.
[0142]
<Charge generation layer: CGL>

The above composition was mixed and dispersed using a sand mill to prepare a coating solution for the charge generation layer. This coating solution was applied by dip coating to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.
[0143]
<Charge transport layer 1 (CTL1)>

Was mixed and dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied on the charge generation layer by a dip coating method, and dried at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 10.0 μm.
[0144]
<Preparation of 4-fluoroethylene resin particle dispersion>

Was mixed with a sand grinder using glass beads (manufactured by Amex Co., Ltd.) to prepare a dispersion of 4-fluoroethylene resin particles.
[0145]
<Charge transport layer 2 (CTL2)>

Was mixed and dissolved to prepare a charge transport layer coating solution 2. This coating solution is applied on the charge transport layer 1 by a circular slide hopper type coater, and dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm. Produced.
[0146]
FIG. 4 shows data obtained by measuring an X-ray diffraction spectrum using a sample in which the charge generation layer was applied to a transparent pet base and dried. The X-ray diffraction spectrum of FIG. 4 is affected by the binder (polyvinyl butyral resin) of the charge generation layer, and is lower than the X-ray diffraction spectrum of the CG-1 pigment of FIG. It has shifted to the angle side.
[0147]
Preparation of Photoconductors 2 to 11 In the preparation of the photoconductor 1, the inorganic particles of the intermediate layer, the thickness of the charge generation layer (CGL), the thickness of the charge transport layers 1 and 2 (CTL1 and 2), and the fluorine-based resin particles were Photoconductors 2 to 11 were produced in the same manner as Photoconductor 1, except that the photoconductors were changed as shown in Table 1.
[0148]
Preparation of Photoconductors 12 and 13 In the preparation of Photoconductor 1, CG-2 and CG-3 were used instead of CG-1 of the charge generation layer, and the fluorine resin particles of the charge transport layer 2 were changed as shown in Table 1. Photoconductors 12 and 13 were produced in the same manner as the photoconductor 1 except for the above.
[0149]
Preparation of Photoreceptor 14 Photoreceptor 14 was prepared in the same manner as for photoreceptor 1 except that the inorganic particles in the intermediate layer were removed and the film thickness was changed to 0.5 μm.
[0150]
Preparation of Photoconductor 15 Photoconductor 15 was prepared in the same manner as photoconductor 1, except that CG-1 in the charge generation layer was changed to Y-TiOPc. Note that Y-TiOPc is a Y-type titanyl phthalocyanine pigment having a maximum peak at 27.2 ° in the X-ray diffraction spectrum (Y-TiOPc in Table 1), and is a pigment synthesized according to the following synthesis example.
[0151]
Synthesis example of Y-type titanyl phthalocyanine pigment A crude titanyl phthalocyanine product is prepared from diiminoisoindoline and titanium tetrabutoxide, dissolved in sulfuric acid, poured into water, and the resulting precipitate is filtered and sufficiently washed with water to obtain an amorphous titanyl phthalocyanine pigment containing water. Get the paste. This pigment-containing paste (approximately 10 g in terms of solid content) was dispersed in a mixed solution of 100 ml of orthodichlorobenzene and 100 ml of water (the aqueous layer was separated), heated at 70 ° C. for 6 hours, and then poured into methanol. The crystals were filtered and dried to obtain a Y-type titanyl phthalocyanine pigment (Y-TiOPc: X-ray diffraction spectrum is FIG. 5).
[0152]
Preparation of Photoreceptor 16 Photoreceptor 16 was prepared in the same manner as in preparation of photoreceptor 1 except that charge transport layer 2 was omitted.
[0153]
The volume resistances of the intermediate layers of the photoconductors 1 to 16 were all 10 ⁸ Ω · cm or more.
[0154]
[Table 1]

[0155]
In Table 1, I, J, and K of the surface treatment of the fine particles indicate the following treatments.
I: Silica-alumina treatment and methylhydrogenpolysiloxane treatment J: Silica-alumina treatment and octyltrimethoxysilane treatment K: Silica-zirconia treatment and methyltrimethoxysilane treatment G and H indicate the following fluororesin fine particles.
[0156]
G: ethylene tetrafluoride resin particles (Lubron L-2, manufactured by Daikin Industries, Ltd.)
H: ethylene trifluoride resin particles (DAIFRON, manufactured by Daikin Industries, Ltd.)
《Evaluation》
Next, each of the above photoconductors was mounted on a Konica Sitios 7040 digital copying machine, and images were formed and evaluated. That is, the photoreceptor was set to a Konica Sitios 7040 digital copying machine (having a scorotron charger, a semiconductor laser image exposure device, and a reversal developing means) basically having the structure shown in FIG. 6, and a copying experiment was performed. In this experiment, the program of the unexposed portion target potential was incorporated into the memory of the process control section in FIG. 6, and the digital copying machine was modified so that the unexposed portion target potential at the developing position was automatically set.
[0157]
《Image evaluation》
Attach each photoreceptor to the above Sitios 7040 digital copier remodeling machine, and copy A4 paper, 50,000 sheets of character images with 7% pixel rate on 50,000 sheets in a high temperature and high humidity (30 ° C., 80% RH) environment. A white image and a halftone image were copied every 10,000 copies, and the presence or absence of image defects such as black spots and white spots was confirmed. Table 2 shows the results.
[0158]
Other evaluation conditions using the above 7040 were set to the following conditions.
Charging condition Charger: Unexposed portion potential (VH) at scorotron charger development position Target: -500V
Exposure conditions Exposure portion potential target: Set to an exposure amount to be -50V.
[0159]
Exposure beam: Image exposure with a dot density of 400 dpi was performed. Laser beam spot area: 0.8 × 10 ^-9 m ² , laser using a semiconductor laser of 680 nm Developing conditions The developer is a carrier coated with an insulating resin with ferrite having a volume average particle diameter of 50 μm as a core and a styrene acrylic resin. A toner developer in which silica and titanium oxide are externally added to colored particles having a volume average particle diameter of 5.3 μm prepared by a polymerization method comprising a resin as a main material, a colorant of carbon black, a charge control agent, and a low molecular weight polyolefin, is used. used.
[0160]
Transfer condition Transfer pole; Corona charging method Separation condition: Cleaning condition using separation means of separation claw unit A cleaning blade having a hardness of 70 °, a rebound resilience of 65%, a thickness of 2 (mm), and a free length of 9 mm is countered in the cleaning section. Was contacted by a weight load method so as to have a linear pressure of 18 (g / cm).
[0161]
Black Spot Image Defect Evaluation Criteria Regarding black spots, the periodicity coincided with the period of the photoconductor, and the number of visible black spots per A4 size was determined.
[0162]
：: Frequency of black spots of 0.4 mm or more: All copied images are 3 copies / A4 or less (good)
：: Black spots of 0.4 mm or more Frequency: 1 or more of 4 / A4 or more and 10 / A4 or less (no problem in practical use)
×: Black spots of 0.4 mm or more Frequency: 11 pieces / A4 or more 1 sheet or more (problem in practice)
Criteria for Evaluation of White Drop Image Defects With respect to white drop, the periodicity coincides with the period of the photoconductor, and the number of visible white drops per A4 size was determined.
[0163]
：: Frequency of white spots of 0.4 mm or more: All copied images 5 / A4 or less (good)
：: White spotting frequency of 0.4 mm or more: Frequency of 6 or more and 20 or less of A4 or less occurred (no problem in practical use)
×: White drop of 0.4 mm or more Frequency: 21 / A4 or more one or more (problem in practical use)
Environmental Memory Environmental Memory: The above-mentioned Styos 7040 copying machine was left under HH for 24 hours, then placed under low humidity and low temperature (LL: 20 RH%, 10 ° C.), and copied after 30 minutes. A halftone image having a density of 0.4 is copied to a density of 0.4 in the original image, and a determination is made based on a density difference (ΔHD = maximum density−minimum density) of the copied image ◎: ΔHD is 0.05 or less (good)
：: ΔHD is larger than 0.05 and smaller than 0.1 (no problem in practical use)
×: ΔHD is 0.1 or more (there is a problem in practical use)
Image blur An image is formed in a high-temperature and high-humidity environment (33 ° C./80% RH) using an original image having a grid image with a width of 5 cm produced by lines of 0.1 mm intervals, and the image is magnified 20 times. Then, the sharpness and independence of the lines were observed.
[0164]
◎: There is no image blur, and each line image is reproduced within a range of ± 20% of the original image (good)
：: Image blur is small, and each line image is reproduced within the range of ± (21 to 40%) of the original image (no problem in practical use)
Δ: Image blur is large, and each line image is reproduced within a range of ± (41 to 75%) of the original image (not suitable for high gradation image quality).
×: Image blur is remarkable, each line image is ± 76% or more of the original image, or the line interval is broken (a problem in practical use)
Evaluation of Image Density, Gradation and Sharpness The above evaluation conditions were changed to a normal temperature and normal humidity (20 ° C., 60% RH) environment, and an original image having 50 gradation steps from a white image to a solid black image was copied. Then, the image density and the gradation were evaluated. In the evaluation, the gradation density of the copied image was measured using RD-918 manufactured by Macbeth. The relative reflection density was measured with the reflection density of the paper being "0".
[0165]
(Image density)
A: Black solid portion density of 1.3 or more (good)
：: Black solid portion density of 1.0 to less than 1.3 (no problem in practical use)
Δ: Black solid portion density of 0.7 to less than 1.0 (re-evaluation required)
×: Density of black solid portion is less than 0.7 (practical problem)
(Gradation)
：: 25 gradations or more (good)
Good: 15 to 24 gradations (no problem in practical use)
Δ: 5 to 14 gradations (not suitable for high gradation image quality)
×: Gradation of 4 steps or less (problematic in practice)
(Sharpness)
The sharpness of the image was evaluated by forming an image in a high-temperature and high-humidity (30 ° C., 80% RH) environment under severe environmental conditions and evaluating the character collapse. Character images having different character sizes (points) were formed and evaluated according to the following criteria.
[0166]
◎: Characters of 4 points or less are clear and easily legible (good)
：: Characters of 6 points or less are clear and easily legible (no problem in practical use)
△: Characters of 8 points or less are clear and easily legible (re-evaluation required)
×: Some or all of the 8-point characters are illegible (practical problem)
[0167]
[Table 2]

[0168]
As is clear from Table 2, the conditions of the photoreceptor of the present invention (the charge generation layer containing the charge generation substance of the adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms, and the total film thickness) Is a charge transport layer having a thickness of 5 to 15 μm, and the uppermost charge transport layer contains a fluororesin particle. Nos. 1 to 3 and 6 to 14 are the evaluation items of the photosensitive member No. other than the present invention in each of the evaluation items of black spots, white spots, environmental memory, image blur, image density, gradation, and sharpness. Good results were achieved for 4, 5, 15, and 16. In particular, a photoconductor (No. 1 to 3, 6 to 6) in which an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms is used, and the uppermost charge transport layer contains fluororesin particles. 9, 14) have a remarkable improvement effect. On the other hand, the photoreceptor 4 having a charge transport layer having a total film thickness of 16 μm has poor image blur and poor sharpness, and the photoreceptor 5 having a charge transport layer having a total film thickness of 4 μm has a charging potential of 500 V which is a target. , And the image quality is reduced overall. Also, the photoreceptor 15 having only the P-type pigment as the charge generating material has poor environmental memory and low sharpness. In the photoreceptor 16 in which the uppermost charge transport layer does not contain fluorine resin particles, black spots and white spots frequently occur, and the sharpness is also reduced.
[0169]
【The invention's effect】
By using the organic photoreceptor of the present invention, the generation of image defects such as black spots, white spots, environmental memory, and image blurring is reduced, and an electrophotographic image having high image density and high gradation can be obtained. Further, it is possible to provide an image forming method and an image forming apparatus capable of forming a good electrophotographic image using the organic photoreceptor of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram of an X-ray diffraction spectrum of CG-1.
FIG. 2 is a diagram of an X-ray diffraction spectrum of CG-2.
FIG. 3 is a diagram of an X-ray diffraction spectrum of CG-3.
FIG. 4 is a view showing an X-ray diffraction spectrum of a charge generation layer of the photoreceptor 1.
FIG. 5 is an X-ray diffraction spectrum of a Y-type titanyl phthalocyanine pigment.
FIG. 6 is a schematic diagram in which functions of the image forming apparatus of the present invention are incorporated.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 image forming apparatus 21 photoreceptor 22 charging means 23 developing means 24 transfer pole 25 separation pole 26 cleaning apparatus 30 exposure optical system 45 transfer and transport belt apparatus 50 fixing means 250 separation claw unit

Claims (6)

A charge generation layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms on a conductive support, and at least one layer having a total film thickness of 5 to 15 μm on the charge generation layer An organic photoreceptor having the above laminated structure, wherein the uppermost layer contains fluorine resin particles. An intermediate layer containing inorganic particles on a conductive support, a charge generating layer containing an adduct pigment of titanyl phthalocyanine and a diol having a hydroxyl group at each of two adjacent carbon atoms, and a total film thickness on the charge generating layer Has a laminated structure of at least one layer having a thickness of 5 to 15 μm, and the uppermost layer contains fluorine resin particles. The organic photoconductor according to claim 2, wherein the intermediate layer is a semiconductive or insulating layer having a volume resistance of 10 ⁸ Ω · cm or more. An image forming method comprising forming an electrophotographic image using the organic photoreceptor according to claim 1. An image forming apparatus that forms an electrophotographic image by using the image forming method according to claim 4. An organic photoreceptor according to claim 1, charging means for uniformly charging the organic photoreceptor, a latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, Developing means for visualizing the electrostatic latent image on the organic photoreceptor, transfer means for transferring the toner image visualized on the organic photoreceptor onto a transfer material, At least one of a charge removing means for removing charge and a cleaning means for removing toner remaining on the organic photoreceptor after transfer is integrally supported, and can be detachably attached to the image forming apparatus main body. A process cartridge.

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