JP2004191690A - Electrophotographic photoreceptor, image forming apparatus using the same, and process cartridge for image forming apparatus - Google Patents

Abstract

An inexpensive and highly durable electrophotographic photoreceptor having a reduced surface friction coefficient, good electrophotographic properties, and capable of performing stable image formation and cleaning over a long period of time.
An electrophotographic photosensitive member having at least a laminated or single-layer photosensitive layer on a conductive support, wherein the outermost layer of the photosensitive member contains at least lanolin or a derivative thereof. An image forming apparatus using the electrophotographic photosensitive member, an image forming method, and a process cartridge for the image forming apparatus.
[Selection diagram] None

Description

【００６４】
電荷輸送層中にこれらラノリン又はその誘導体を含有させる場合、より効率良く摩擦係数軽減効果を得るためには、電荷輸送層の表面付近の含有量を多くすることが好ましい。すなわち、摩擦係数低減の効果を発揮するのは感光体表面に存在するラノリン又はその誘導体であるため、電荷輸送層の表面より内部に含有したラノリン又はその誘導体は無駄になってしまう上、逆に感光体の電子写真特性に悪影響を与える可能性もある。ラノリン又はその誘導体を電荷輸送層の表面付近に多く含有させる電子写真感光体の製造方法としては、例えば、ラノリン又はその誘導体の含有量が異なる電荷輸送層形成用塗工液を複数用意し、含有量の少ない液から順次塗工するなどの方法が考えられる。
【００６５】
例えば、電荷発生層上に、まずラノリン又はその誘導体を含有しない電荷輸送層形成用塗工液を用いて第１の電荷輸送層を形成し、その上からラノリン又はその誘導体の含有量が５０％の電荷輸送層形成用塗工液を用いて第２の電荷輸送層を形成し、乾燥することによって、表面にラノリン又はその誘導体が多く含有した電荷輸送層が形成できる。
塗工方法としては、浸漬塗工に限らず、スプレー塗工など公知の方法が考えられる。
【００６６】
ラノリン又はその誘導体の含有量としては、最表層の全固形分の１〜７５ｗｔ％の範囲であることが好ましい。１ｗｔ％より少ないと、摩擦係数低減効果が不十分となり、前述の様々な効果が得られない。
また７５ｗｔ％よりも多い場合、ラノリン又はその誘導体それ自体は成膜性が小さいために、良好な塗膜が得られなかったり、感光体の電気特性への不具合、例えば残留電位の上昇や光感度の低下などを引き起こす恐れがある。
【００６７】
また、本発明の感光体は、電荷輸送層が最表層になる場合には、電荷輸送層にフィラーを含有しても良い。
フィラー材料としては、有機性フィラー材料と無機性フィラー材料とがある。有機性フィラー材料としては、ポリテトラフルオロエチレンのようなフッ素樹脂粉末、シリコーン樹脂粉末、ａ−カーボン粉末等が挙げられ、無機性フィラー材料としては、銅、スズ、アルミニウム、インジウムなどの金属粉末、シリカ、酸化錫、酸化亜鉛、酸化チタン、アルミナ、酸化インジウム、酸化アンチモン、酸化ビスマス、酸化カルシウム、アンチモンをドープした酸化錫、錫をドープした酸化インジウム等の金属酸化物、フッ化錫、フッ化カルシウム、フッ化アルミニウム等の金属フッ化物、チタン酸カリウム、窒化硼素などの無機材料が挙げられる。
【００６８】
無機材料からなるフィラーは、有機材料からなるフィラーに比べ硬度が高いため、感光体最表層の耐摩耗性をより向上させることができる。ところが、一般的に、潜像担持体の耐摩耗性を向上させると該潜像担持体の表面部はほとんど摩耗しなくなるが、帯電時に発生するオゾン、ＮＯｘ等の反応性ガスによって該表面部が低抵抗化し、次第に該表面部の静電荷が保持されなくなり、該静電荷が表面方向に移動してしまうことが知られている。その結果、静電潜像が滲んでしまい、該静電潜像がトナーなどで現像されたときに見られる画像ボケや画像流れと呼ばれる異常画像が起こるようになる。そこで、本発明で用いるフィラーとしては１０¹⁰Ωｃｍ以上という高い抵抗を有することが好ましい。このようなフィラーを用いることで、潜像担持体の最表層の低抵抗化が抑えられ、上記異常画像の発生を大幅に抑制することができる。
【００６９】
これらのフィラーの中で、特に、シリカ、酸化チタン、アルミナが有効に使用できる。また、これらのフィラー材料は他の金属酸化物微粒子に比べ価格が安く入手も容易なため、潜像担持体の製造コスト低減を図ることが可能となる。
その中でも高い絶縁性を有し、熱安定性が高い上に、耐摩耗性が高い六方最密構造であるα型アルミナは、画像ボケの抑制や耐摩耗性の向上の点から特に有用である。このようなフィラー材料は単独もしくは２種類以上を混合して用いてもよい。
【００７０】
これらのフィラー材料は、電荷輸送物質や結着樹脂、溶媒等とともに適当な分散機を用いることにより分散できる。また、フィラーの一次粒径の平均は、０．０５〜１．０μｍ、好ましくは０．１〜０．３μｍである。
フィラーの平均一次粒径が０．０５μｍよりも小さすぎると耐摩耗性が不十分となる場合がある。一方、フィラーの平均一次粒径が１．０μｍよりも大きすぎると潜像担持体に照射される光書き込み光が該フィラーで散乱して透過率が低下し、画像ボケや文字太りが生じてしまうことがある。
【００７１】
表面層中のフィラー濃度は使用するフィラー種により、また感光体を使用する電子写真プロセス条件によっても異なるが、５〜６０重量％が好ましい。また、これらのフィラーを電荷輸送層全体に含有させることも可能であるが、露光部電位が高くなるような場合があるため、電荷輸送層の最表面側が最もフィラー含有率が高く、導電性支持体側が低くなるようにフィラー濃度傾斜を設けたり、電荷輸送層を複数層にして、導電性支持体側から表面側に向かい、フィラー濃度が順次高くしたりするような構成にすることが好ましい。
【００７２】
次に、感光層が単層構成の場合について説明する。
キャスティング法で単層感光層を設ける場合、多くの場合、かかる単層感光層は、電荷発生物質と低分子並びに高分子電荷輸送性物質を適当な溶剤に溶解ないし分散し、これを塗布、乾燥することにより形成できる。電荷発生物質並びに電荷輸送性物質としては、前述した材料を用いることができる。
【００７３】
また、かかる単層感光層には、必要により、可塑剤を添加することもできる。更に、必要に応じて用いることのできるバインダー樹脂としては、先に電荷輸送層で挙げたバインダー樹脂をそのまま用いることができる。その他に、電荷発生層で挙げたバインダー樹脂を混合して用いてもよい。
【００７４】
さらに、単層感光層が感光体の最表層となる場合には、少なくとも該単層感光層にラノリン又はその誘導体を含有する。
これによって、前述の電荷輸送層にラノリン又はその誘導体を含有させる場合と同じ効果が得られる。
【００７５】
また、前述の電荷輸送層にラノリン又はその誘導体を含有させる場合と同様に、表面付近のラノリン又はその誘導体の含有量を多くするのが好ましく、その方法も同様の製造方法を用いることができる。
単層感光体の感光層の膜厚は、５〜１００μｍ程度が適当である。
【００７６】
本発明の感光体においては、感光層の上に、保護層が設けられることもある。保護層に使用される材料としてはＡＢＳ樹脂、ＡＣＳ樹脂、オレフィン−ビニルモノマー共重合体、塩素化ポリエーテル、アリール樹脂、フェノール樹脂、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアクリレート、ポリアリルスルホン、ポリブチレン、ポリブチレンテレフタレート、ポリカーボネート、ポリエーテルスルホン、ポリエチレン、ポリエチレンテレフタレート、ポリイミド、アクリル樹脂、ポリメチルベンテン、ポリプロピレン、ポリフェニレンオキシド、ポリスルホン、ポリスチレン、ポリアリレート、ＡＳ樹脂、ブタジエン−スチレン共重合体、ポリウレタン、ポリ塩化ビニル、ポリ塩化ビニリデン、エポキシ樹脂等の樹脂が挙げられる。
【００７７】
また、保護層を用いる場合、保護層が最表層となるので、該保護層中にラノリン又はその誘導体を含有する。保護層は主に耐摩耗性の向上を目的としている。本発明においては、ラノリン又はその誘導体を含有することで摩擦係数が低減し、耐摩耗性が向上する。さらに、保護層は感光層の上に比較的小さな膜厚をもって設けられるため、感光体の電気特性への影響が比較的小さく、電荷輸送層にラノリン又はその誘導体を含有させる場合よりも、含有量を大きくすることができる。そのため、保護層にラノリン又はその誘導体をより多く含有することで、いっそうの摩擦係数の低減を達成することができる。
【００７８】
また、保護層にはさらなる耐摩耗性を付与するためにフィラー材料を含有してもよい。フィラーとしては、前述のものを用いることができ、また、これらのフィラー材料は単独もしくは２種類以上を混合して用いられる。
【００７９】
また、保護層に電荷輸送物質を含有させることも感光体の電気特性、特に繰り返し使用時の光感度劣化、残留電位の上昇を抑制するのに非常に有用である。これは、保護層にも電荷輸送性を持たせることで、感光体表面までスムーズに電荷が移動できるようになるためである。かかる電荷輸送性物質としては、先に挙げた電荷輸送層で用いられる電荷輸送性物質を用いることができる。
【００８０】
更に、本発明に係る電子写真感光体の保護層には、接着性、平滑性、化学的安定性を向上させる目的で、種々の添加剤を加えてもかまわない。
【００８１】
本発明にかかる保護層は、浸漬塗工、スプレー塗工、ブレード塗工、ナイフ塗工等の常法の塗工方法を用いて感光層上に形成される。特に、量産性、塗膜品質などの面から浸漬塗工、スプレー塗工が有利である。
保護層の膜厚は０．１〜１０μｍの範囲が適当である。
【００８２】
次に本発明の画像形成装置について、図を参照して説明する。
図５は、本発明の画像形成装置を説明するための概略図である。なお、下記するような変形例も本発明の範疇に属するものである。
図５に示すように、本発明に係る電子写真感光体を用いた画像形成装置は、本発明に係るドラム状の感光体１と、帯電チャージャ３と、転写前チャージャ７と、転写チャージャ１０と、分離チャージャ１１と、クリーニング前チャージャ１３などから構成されている。なお、感光体１の形状は、ドラム状の形状に限定されるものではなく、例えば、シート状、エンドレスベルト状のものであっても良い。また、各種チャージャーとしては、コロトロン、スコロトロン、固体帯電器（ソリッド・ステート・チャージャ）、帯電ローラを始めとする公知の手段を用いることができる。
転写手段としては、一般には上記の帯電器が使用できるが、図示するような転写チャージャと分離チャージャとを併用したものが効果的である。
【００８３】
また、画像露光部５、除電ランプ２等の光源には、蛍光灯、タングステンランプ、ハロゲンランプ、水銀灯、ナトリウム灯、発光ダイオード（ＬＥＤ）、半導体レーザー（ＬＤ）、エレクトロルミネッセンス（ＥＬ）などの発光物全般を用いることができる。そして、所望の波長域の光のみを照射するために、シャープカットフィルター、バンドパスフィルター、近赤外カットフィルター、ダイクロイックフィルター、干渉フィルター、色温度変換フィルターなどの各種フィルターを用いることもできる。
かかる光源等は、図５に示される工程の他に、光照射を併用した転写工程、除電工程、クリーニング工程、あるいは前露光などの工程を設けることにより、感光体に光を照射することができる。
【００８４】
さて、現像ユニット６により感光体１上に現像されたトナーは、転写紙９に転写されるが、全部が転写されるわけではなく、感光体１上にトナーが残存する。このようなトナーは、クリーニングブラシ１４及びブレード１５により、感光体より除去される。クリーニングは、クリーニングブラシ又はブレード単独で行なわれることもあり、クリーニングブラシにはファーブラシ、マグファーブラシを始めとする公知のものが用いられる。
【００８５】
電子写真感光体に正(負)帯電を施し、画像露光を行なうと、感光体表面上には正(負)の静電潜像が形成される。これを負(正)極性のトナー（検電微粒子）で現像すれば、ポジ画像が得られるし、また正(負)極性のトナーで現像すれば、ネガ画像が得られる。かかる現像手段としては、公知の方法が適用され、また、除電手段にも公知の方法が用いられる。
【００８６】
図６には、本発明による画像形成装置を用いた別のプロセスの例を示す。図６において、感光体２２は、本発明の電子写真感光体であり、駆動ローラ２３により駆動され、帯電チャージャ２０による帯電、光源２１による像露光、現像（図示せず）、帯電器２５を用いる転写、ブラシ２６によるクリーニング、光源２７による除電が繰返し行なわれる。
【００８７】
さらに、本発明を適用したフルカラー画像形成装置として、電子写真方式のプリンタ（以下、単にプリンタという）の一実施形態について説明する。
図７は、本実施形態に係るプリンタの概略構成図である。図において、潜像担持体たる感光体５６は、図中反時計回りに回転駆動されながら、その表面がコロトロンやスコロトロンなどを用いる帯電チャージャ５３によって一様帯電せしめられた後、図示しないレーザ光学装置から発せられるレーザ光Ｌの走査を受けて静電潜像を担持する。この走査はフルカラー画像をイエロー、マゼンタ、シアン及びブラックの色情報に分解した単色の画像情報に基づいてなされるため、感光体ドラム５６上にはイエロー、マゼンタ、シアン又はブラックという単色用の静電潜像が形成される。感光体ドラム５６の図中左側には、リボルバ現像ユニット５０が配設されている。これは、回転するドラム状の筺体の中にイエロー現像器、マゼンタ現像器、シアン現像器、ブラック現像器を有しており、回転によって各現像器を感光体ドラム５６に対向する現像位置に順次移動させる。なお、イエロー現像器、マゼンタ現像器、シアン現像器、ブラック現像器は、それぞれイエロートナー、マゼンタトナー、シアントナー、ブラックトナーを付着せしめて静電潜像を現像するものである。感光体ドラム５６上には、イエロー、マゼンタ、シアン、ブラック用の静電潜像が順次形成され、これらはリボルバ現像ユニット５０の各現像器によって順次現像されてイエロートナー像、マゼンタトナー像、シアントナー像、ブラックトナー像となる。
【００８８】
上記現像位置よりも感光体ドラム５６の回転下流側には中間転写ユニットが配設されている。これは、張架ローラ５９ａ、転写手段たる中間転写バイアスローラ５７、２次転写バックアップローラ５９ｂ、ベルト駆動ローラ５９ｃによって張架している中間転写ベルト５８を、ベルト駆動ローラ５９ｃの回転駆動によって図中時計回りに無端移動せしめる。感光体ドラム５６上で現像されたイエロートナー像、マゼンタトナー像、シアントナー像、ブラックトナー像は、感光体ドラム５６と中間転写ベルト５８とが接触する中間転写ニップに進入する。そして、中間転写バイアスローラ５７からのバイアスの影響を受けながら、中間転写ベルト５８上に重ね合わせて中間転写されて、４色重ね合わせトナー像となる。
【００８９】
回転に伴って中間転写ニップを通過した感光体ドラム５６表面は、ドラムクリーニングユニット５５によって転写残トナーがクリーニングされる。このクリーニングユニット５５は、クリーニングバイアスが印加されるクリーニングローラによって転写残トナーをクリーニングするものであるがファーブラシ、マグファーブラシ等からなるクリーニングブラシや、クリーニングブレードなどを用いるものであってもよい。
【００９０】
転写残トナーがクリーニングされた感光体ドラム５６表面は、除電ランプ５４によって除電せしめられる。除電ランプ５４には、蛍光灯、タングステンランプ、ハロゲンランプ、水銀灯、ナトリウム灯、発光ダイオード（ＬＥＤ）、半導体レーザ（ＬＤ）、エレクトロルミネッセンス（ＥＬ）などが用いられている。また、上記レーザ光学装置の光源には半導体レーザが用いられている。これら発せられる光については、シャープカットフィルター、バンドパスフィルター、近赤外カットフィルター、ダイクロイックフィルター、干渉フィルター、色温度変換フィルターなどの各種フィルターにより、所望の波長域だけを用いるようにしてもよい。
【００９１】
中間転写ユニットの図中下側には、転写ベルトと転写バイアスローラー、駆動ローラー等各種ローラーからなる転写ユニットが配設されており、これの図中左側には、搬送ベルト６４、定着ユニット６５が配設されている。転写ユニットは、無端移動する転写ベルトは、図示しない移動手段によって図中上下方向に移動するようになっていてもよく、少なくとも、中間転写ベルト５８上の１色トナー像（イエロートナー像）や、２色又は３色重ね合わせトナー像が紙転写バイアスローラ６３との対向位置を通過する際には、中間転写ベルト５８に接触しない位置まで待避移動する。そして、中間転写ベルト５８上の４色重ね合わせトナー像の先端が紙転写バイアスローラー６３との対向位置に進入してくる前に、中間転写ベルト５８との接触位置まで移動して２次転写ニップを形成する。
【００９２】
一方、図示しない給紙カセットから送られてきた転写紙６０を２つのローラ間に挟み込んでいるレジストローラ対６１は、転写紙６０を中間転写ベルト５８上の４色重ね合わせトナー像に重ね合わせ得るタイミングで上記２次転写ニップに向けて送り込む。中間転写ベルト５８上の４色重ね合わせトナー像は、２次転写ニップ内で紙転写バイアスローラー６３からの２次転写バイアスの影響を受けて転写紙Ｐ上に一括して２次転写される。この２次転写により、転写紙６０上にはフルカラー画像が形成される。
【００９３】
フルカラー画像が形成された転写紙６０は、転写ベルト６２によって紙搬送ベルト６４に送られる。
搬送ベルトは６４は、転写ユニットから受け取った転写紙６０を定着ユニット６５内に送り込む。
定着ユニット６５は、送り込まれた転写紙６０を加熱ローラとバックアップローラとの当接によって形成された定着ニップに挟み込みながら搬送する。
転写紙６０上のフルカラー画像は、加熱ローラからの加熱や、定着ニップ内での加圧力の影響を受けて転写紙６０上に定着せしめられる。
【００９４】
なお、図示を省略しているが、転写ベルト６２や搬送ベルト６４には、転写紙Ｐを吸着させるためのバイアスが印加されている。また、転写紙６０を除電する紙除電チャージャや、各ベルト（中間転写ベルト５８、転写ベルト６２、搬送ベルト６４）を除電する３つのベルト除電チャージャが配設されている。また、中間転写ユニットは、ドラムクリーニングユニット５５と同様の構成のベルトクリーニングユニットも備えており、これによって中間転写ベルト５８上の転写残トナーをクリーニングする。
【００９５】
図８は、本実施形態に係るプリンタの変形例である。この装置は、いわゆるタンデム方式のプリンタであり、感光体ドラム８０を各色で共有させるのではなく、各色用の感光体ドラム８０Ｙ、８０Ｍ、８０Ｃ、８０Ｂｋを備えている。また、ドラムクリーニングユニット８５、除電ランプ８３、ドラムを一様帯電せしめる帯電ローラ８４も、各色用のものを備えている。なお、図７に示したプリンタではドラム一様帯電手段として帯電チャージャ５３を設けていたが、このプリンタでは帯電ローラ８４を設けている。
タンデム方式では、各色の潜像形成や現像を並行して行うことができるため、リボルバ式よりも画像形成速度を遙かに高速化させることができる。
【００９６】
【実施例】
以下、本発明を実施例により説明するが、本発明は、下記実施例の態様に限定されるものではない。
【００９７】
実施例１
アルキッド樹脂（ベッコライトＭ６４０１−５０（大日本インキ化学工業社製））１５重量部、メラミン樹脂（スーパーベッカミンＧ−８２１−６０（大日本インキ化学工業社製））１０重量部をメチルエチルケトン１５０重量部に溶解し、これに酸化チタン粉末（タイペールＣＲ−ＥＬ（石原産業社製））９０重量部を加えボールミルで１２時間分散し、下引層用塗工液を作製した。
これをφ３０ｍｍの円筒状アルミニウム基体に浸漬塗工法によって塗工し１３０℃２０分間乾燥し厚み３．５μｍの下引き層を形成した。
【００９８】
次にポリビニルブチラール樹脂（ＸＹＨＬ（ＵＣＣ社製））４重量部をシクロヘキサノン１５０重量部に溶解し、これに下記構造式（１）に示すビスアゾ顔料１０重量部を加え、ボールミルで４８時間分散後、さらにシクロヘキサノン２１０重量部を加えて３時間分散を行った。これを容器に取り出し固形分が１．５重量％となるようにシクロヘキサノンで稀釈した。こうして得られた電荷発生層用塗工液を前記中間層上に塗工し１３０℃２０分間乾燥し厚み０．２μｍの電荷発生層を形成した。。
【００９９】
【化２】

【０１００】
次に、テトラヒドロフラン１００重量部に、ビスフェノールＺ型ポリカーボネート樹脂１０重量部、シリコーンオイル（ＫＦ−５０（信越化学工業社製））０．００２重量部を溶解し、これに下記構造式（２）の電荷輸送物質１０重量部を加えて電荷輸送層用塗工液を作製した。こうして得られた電荷輸送層用塗工液を電荷発生層上に浸漬塗工法によって塗工し、その後１１０℃２０分間乾燥し、厚み２０μｍの電荷輸送層を形成した。
【０１０１】
【化３】

【０１０２】
次に、テトラヒドロフラン２８０重量部とシクロヘキサノン８０重量部の混合溶媒に、精製ラノリン（商品名：ラノリンＴＲ 日本精化社製）３重量部、ビスフェノールＺ型ポリカーボネート樹脂７重量部を溶解し、保護層形成用塗工液を作製した。こうして得られた保護層形成用塗工液を電荷輸送層上にスプレー塗工法によって塗工し、その後１３０℃２０分間乾燥し、厚み６μｍの保護層を形成し、電子写真感光体を作製した。
【０１０３】
実施例２
精製ラノリンの代わりに、ラノリン脂肪酸金属石鹸（商品名：ネオコート ＯＦ−３３０１ 日本精化社製）を用いた以外は実施例１と同様にして電子写真感光体を作製した。
【０１０４】
実施例３
精製ラノリンの代わりに、ラノリン脂肪酸多価アルコールエステル（商品名：ネオコート ＥＰ−２ 日本精化社製）を用いた以外は実施例１と同様にして電子写真感光体を作製した。
【０１０５】
実施例４
保護層に用いたビスフェノールＺ型ポリカーボネート樹脂７重量部、精製ラノリン３重量部を、ビスフェノールＺ型ポリカーボネート樹脂９．５重量部、精製ラノリン０．５重量部とした以外は実施例１と同様にして、電子写真感光体を作製した。
【０１０６】
実施例５
保護層に用いたビスフェノールＺ型ポリカーボネート樹脂７重量部、精製ラノリン３重量部を、ビスフェノールＺ型ポリカーボネート樹脂３重量部、精製ラノリン７重量部とした以外は実施例１と同様にして、電子写真感光体を作製した。
【０１０７】
実施例６
保護層に用いたビスフェノールＺ型ポリカーボネート樹脂７重量部を、ビスフェノールＺ型ポリカーボネート樹脂４重量部とし、更に前記構造式（２）の電荷輸送物質３重量部を加えた以外は実施例１と同様にして、電子写真感光体を作製した。
【０１０８】
実施例７
実施例１で用いた保護層塗工液の代わりに、テトラヒドロフラン８０重量部とシクロヘキサノン２８０重量部の混合溶媒に、ビスフェノールＺ型ポリカーボネート樹脂４重量部、前記構造式（２）の電荷輸送物質３重量部、精製ラノリン３重量部を溶解し、アルミナ微粒子（平均粒径０．３μｍ）０．２重量部を加えて、ボールミルで２時間分散して得られた保護層形成用塗工液を用いた以外は実施例１と同様にして、電子写真感光体を作製した。
【０１０９】
実施例８
アルミナ微粒子の代わりにシリカ微粒子（平均粒径０．３μｍ）を用いた以外は、実施例７と同様にして、電子写真感光体を作製した。
【０１１０】
比較例１
保護層形成用塗工液に精製ラノリンを加えなかった以外は実施例１と同様にして、電子写真感光体を作製した。
【０１１１】
比較例２
保護層形成用塗工液に精製ラノリンを加えなかった以外は実施例７と同様にして、電子写真感光体を作製した。
【０１１２】
比較例３
精製ラノリンの代わりに、四フッ化エチレン樹脂微粒子（商品名：ルブロンＬ−２ ダイキン工業社製）を用いた以外は実施例１と同様にして、電子写真感光体を作製したところ、四フッ化エチレン微粒子が塗工液中で凝集、沈殿してしまった。また、塗工液を攪拌しつつスプレー塗工によって形成した保護層塗膜表面は粗くなってしまった。
【０１１３】
比較例４
精製ラノリンの代わりに、シリコーンオイル（商品名：ＫＦ−５０ 信越化学工業社製）０．０３５重量部加えた以外は実施例１と同様にして、電子写真感光体を作製した。
【０１１４】
こうして得られた感光体について、図８の作像エンジンを搭載したコピースピード６０枚／分（Ａ４縦）の複写機に搭載して、非露光部電位（ＶＤ）が−７００Ｖになるように帯電器の電圧を調節したのち、６００ｄｐｉ相当の書き込みによって、Ａ４サイズ、画像面積率５％となるテスト画像を出力するランニング試験を５万枚行い、ランニング試験前後の感光層の膜厚の差から、摩耗量を測定した。膜厚測定は、渦電流式膜厚計フィッシャースコープＭＭＳ（フィッシャー製）を用いた。さらに、ランニング試験前の初期画像、ランニング試験後の耐久画像を出力し、画像品質についても評価を行った。
【０１１５】
また、前述の複写機は、クリーニングブレードの当接圧や現像スリーブのニップ、使用するトナーの添加剤などを調整し、感光体の摩耗に対して、より負荷がかかるようにした。
これらの画像評価と摩耗量測定の結果を表１にまとめる。
【０１１６】
【表１】

【０１１７】
【発明の効果】
以上、詳細かつ具体的な説明から明らかなように、本発明は、導電性支持体上に少なくとも感光層を有する電子写真用感光体において、該感光層の最表層に少なくともラノリン又はその誘導体を有することで、表面の摩擦係数を低減でき、その結果、虫食い版画、クリーニング不良などの異常画像を大幅に低減することができる。また、ラノリン又はその誘導体は、有機溶媒に容易に溶解又は分散するので、塗工液の安定性が高く、良好な塗膜が得られる。さらに、耐摩耗性も向上するので、長期間繰り返し使用しても、上記のような異常画像が発生せず、良好な画像が安定して出力される、電子写真感光体、画像形成装置、タンデムフルカラー画像形成装置、および画像形成装置用プロセスカートリッジが提供されるという極めて優れた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の電子写真感光体の層構成の一例を示す模式断面図である。
【図２】本発明の電子写真感光体の層構成の他の一例を示す模式断面図である。
【図３】本発明の電子写真感光体の層構成の他の一例を示す模式断面図である。
【図４】本発明の電子写真感光体の層構成の他の一例を示す模式断面図である。
【図５】本発明の画像形成装置の一例の概略図である。
【図６】本発明の画像形成装置の他のプロセスを示す概略図である。
【図７】本発明の画像形成装置の例であるプリンタの概略構成図である。
【図８】本発明の画像形成装置の例であるプリンタの変形装置例の概略構成図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member used for a copying machine, electrostatic printing, a printer, electrostatic recording, and the like, an image forming apparatus using the same, an image forming method, and a process cartridge for the image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic method, a uniformly charged photoconductor is irradiated with writing light modulated by image data, and the photoconductor is irradiated on the photoconductor. An electrostatic latent image is formed, and a toner is supplied from a developing unit to the photoreceptor on which the electrostatic latent image has been formed, and a toner image is formed on the photoreceptor and developed. The image forming apparatus transfers the toner image on the photoreceptor to transfer paper (recording paper) at a transfer unit, and then heats and presses the toner transferred on the transfer paper at a fixing unit to fix the toner image. The collected toner is collected by a method such as scraping the toner with a cleaning blade in a cleaning unit.
[0003]
In an image forming apparatus using such an electrophotographic method, it has been conventionally known that by lowering the friction coefficient of the surface of a photoreceptor, unnecessary toner is prevented from adhering and an image free from background contamination can be obtained. Have been. Further, the photoreceptor having a small surface friction coefficient can reduce the amount of wear on the surface and prolong the life of the photoreceptor.
[0004]
That is, the cause of determining the life of the photoconductor is abrasion of the photoconductor layer of the photoconductor, and when a certain amount of the photoconductor layer is removed, the electrical characteristics of the photoconductor are changed so that an appropriate image forming process can be performed. Disappears. This friction occurs in all the contacting parts of the photoconductor and other image forming units such as a developing unit and a transfer unit in the above-described image forming process. It is possible to reduce the abrasion generated at the site and improve the life of the photoconductor.
[0005]
Further, it is known that the transfer rate when a toner image formed on a photoconductor is transferred to a transfer target body is improved by reducing the friction coefficient of the photoconductor surface. That is, it is possible to suppress the worm-eating print and reduce the amount of the residual toner after the transfer, so that there is an effect of reducing the amount of waste toner.
[0006]
As a method for reducing the friction coefficient of the photoconductor surface, an image forming apparatus provided with a mechanism for supplying a lubricant to the photoconductor surface has been conventionally proposed, as proposed in Japanese Patent Application Laid-Open No. H11-216, and has been proposed. Has been However, the provision of such a mechanism around the photoreceptor inevitably increases the size and complexity of the apparatus, and causes problems such as an increase in cost and deterioration in maintenance.
[0007]
As a different method for lowering the friction coefficient of the photoconductor, it has been proposed to add a lubricant to the photoconductor surface layer so as to reduce the friction coefficient. Specifically, there are proposals in Patent Documents 2 to 35 and the like.
Known lubricants include powders such as fluorine atom-containing resins such as polytetrafluoroethylene, spherical acrylic resins and polyethylene resins, and metal oxide powders such as silicon oxide and aluminum oxide. In particular, a fluorine atom-containing resin containing a large amount of fluorine atoms has a remarkably small surface energy, and thus has a large effect as a lubricant. Such a fluorine atom-containing resin is used as crystalline fine particles, and after being dispersed in a binder resin such as an acrylic resin, a polyester resin, a polyurethane resin, and a polycarbonate resin, is formed as a surface layer or a protective layer of the photoconductor. Filmed.
[0008]
However, fluorine atom-containing resin fine particles have problems in their dispersibility and cohesiveness, and it is difficult to form a uniform and smooth film, and the obtained surface layer causes image defects such as image unevenness and pinholes. Having had to be avoided. Further, in most cases, the binder resin and the dispersing agent having good dispersibility deteriorated the electrical characteristics of the photoreceptor, and no effective one was found. When a fluorine-based comb type graft polymer is used as an example of the dispersing aid, the dispersibility of the fluorine-based resin particles is good, but there is a problem that the image quality is deteriorated due to repeated use under high humidity. That is, the residual potential increased due to repeated use, and image fogging occurred.
[0009]
Further, since the fluorine atom-containing resin fine particles are merely dispersed in the binder resin, in the initial state of the photoconductor, the fine particles are wrapped in the binder, that is, the fine particles directly appear on the surface of the photoconductor. Not necessarily. Therefore, the fine particles do not contribute to the friction coefficient in the initial state of the photoconductor at all, and the friction coefficient of the binder is the friction coefficient of the photoconductor as it is. It is necessary to design the surface roughness so as to be within a suitable range, or to mechanically polish the surface as proposed in Patent Document 37, which increases the cost of the photoconductor. Was.
[0010]
Patent Document 38 proposes that a protective layer is provided on a photosensitive layer, and wax is contained in the protective layer to improve the wear resistance of the photosensitive member. If there is no mechanism for applying and wiping the wax, the abrasion resistance is not sufficient, and if the mechanism is provided, there is a problem that the device becomes large and complicated, leading to an increase in cost.
Further, Patent Document 39 proposes a photoreceptor provided with a photosensitive layer containing a hydroxysteroid in order to improve the durability of the photoreceptor. Hydroxysteroids are small molecules, and Patent Document 39 does not mention reducing μ, and the purpose of addition is also different.
[0011]
As described above, various lubricants and the like are used to reduce the friction coefficient of the surface of the photoreceptor and improve the durability. However, the electric characteristics of the photoreceptor, the dispersibility of the lubricant, and the cost reduction are satisfied. Things were not obtained.
[0012]
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JP-A-63-221355
[Patent Document 34]
JP-A-63-249152
[Patent Document 35]
JP-A-63-31356
[Patent Document 36]
JP-A-5-045920
[Patent Document 37]
JP-A-5-265243
[Patent Document 38]
JP 2000-137345 A
[Patent Document 39]
JP-A-6-161126
[0013]
[Problems to be solved by the invention]
An object of the present invention is to provide an inexpensive and highly durable electrophotographic photoreceptor that can reduce the surface friction coefficient, has good electrophotographic characteristics, and can perform stable image formation and cleaning for a long period of time. I do.
Another object of the present invention is to provide an image forming apparatus using such an electrophotographic photosensitive member.
It is still another object of the present invention to provide an image forming method using such an electrophotographic photosensitive member.
It is still another object of the present invention to provide a process cartridge using such an electrophotographic photosensitive member.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have conducted intensive studies on a protective layer having a reduced surface friction coefficient, a good electrical property of a photoreceptor, and a good dispersibility of a lubricant. In an electrophotographic photoreceptor having at least a laminated or single-layered photosensitive layer, the electrophotographic photoreceptor having a structure containing at least lanolin or a derivative thereof in the outermost layer of the photosensitive layer has a significantly reduced surface friction coefficient, And good dispersibility in the photosensitive layer, and it was found that a good image could be output without causing poor cleaning even after repeated use for a long period of time.
[0015]
The electrophotographic photoreceptor having the outermost layer having such a configuration has a very low coefficient of friction on the surface of the photoreceptor, so that even when used repeatedly for a long period of time, it maintains good cleaning properties and has very little wear. Because it is small, the durability of the photoreceptor is high.
[0016]
Although the reason is not clearly understood, since the structure of lanolin or a derivative thereof is made of a relatively bulky hydrocarbon, the coefficient of friction is reduced by arranging the hydrocarbon site on the photoreceptor surface. It is thought that it is. Further, since the electrophotographic photoreceptor of the present invention has good electrophotographic characteristics, it does not generate an abnormal image such as a decrease in image density and an afterimage, and provides a good image for a long period of time.
[0017]
Although the reason for this is not clearly understood, the structure of lanolin or a derivative thereof is formed of a hydrocarbon, and itself has a functional group serving as a hole trap that prevents charge transfer in the photosensitive layer. It is considered that there is no adverse effect on the electrical characteristics of the photoreceptor because it is not present.
[0018]
Lanolin and its derivatives are inexpensive because they are synthesized and marketed in large quantities from natural products. In addition, many are easily dissolved in organic solvents, and even those that do not dissolve can be easily dispersed by stirring, so that an extra dispersion step is not necessary when preparing a coating liquid, and the cost is very low. Useful.
[0019]
Further, in the present invention, the fact that the above-mentioned lanolin or a derivative thereof is contained in the outermost layer in an amount of 1 to 75 wt% is included as one of more preferable embodiments.
[0020]
According to the experiment, when the content of lanolin or a derivative thereof in the outermost layer was in the range of 1 to 75 wt%, the friction coefficient, abrasion resistance, and electric characteristics of the photoreceptor were good.
[0021]
In the present invention, the photosensitive layer comprises at least a layer containing a charge generating substance and a charge transporting substance, and a protective layer laminated thereon, wherein the protective layer contains lanolin or a derivative thereof. By doing so, an electrophotographic photoreceptor having less adverse effects on the electrical characteristics of the photoreceptor, and having a good friction coefficient and abrasion resistance is provided.
[0022]
Further, in the present invention, an electrophotographic photoreceptor having further improved abrasion resistance is provided by containing at least a filler in the outermost layer.
[0023]
Further, in the present invention, by providing the filler in the outermost layer in an amount of 5 to 60% by weight, an electrophotographic photoreceptor having further excellent abrasion resistance is provided.
[0024]
Further, according to the present invention, by adopting a configuration containing at least metal oxide fine particles as the filler, an even higher abrasion resistance is achieved, and an electrophotographic photoreceptor capable of obtaining a good image even after repeated use for a long period of time. Is provided.
[0025]
Further, according to the present invention, by setting the average primary particle size of the filler to 0.05 to 1.0 μm, wear resistance and reduction in friction coefficient are achieved, and further, surface roughness is reduced and abnormal An electrophotographic photoreceptor in which image reduction is achieved is provided.
[0026]
Further, according to the present invention, by containing at least the charge transport material in the outermost layer, the charge transportability of the outermost layer is remarkably improved, and even in repeated use, deterioration of electrophotographic properties such as an increase in the exposed portion potential occurs. An electrophotographic photoreceptor that is difficult to provide is provided.
[0027]
Further, according to the present invention, there is provided an image forming apparatus having at least the electrophotographic photoreceptor of the present invention, a charging unit, an exposing unit, and a transferring unit, and an image forming method.
[0028]
As a result, abnormal images such as poor cleaning, reduced image density, and background stains are less likely to occur, and good images can be obtained even after repeated use for a long period of time.
[0029]
Further, according to the present invention, there is provided a tandem image forming apparatus having at least a plurality of electrophotographic photosensitive members, a charging unit, an exposing unit, and a transfer unit, and an image forming method.
[0030]
As a result, an excellent full-color image can be obtained at a very high speed as compared with the one-drum type image forming apparatus.
[0031]
Further, according to the present invention, an intermediate transfer means for primary-transferring a toner image developed on an electrophotographic photosensitive member onto an intermediate transfer member, and then secondary-transferring the toner image on the intermediate transfer member onto a recording material An image forming apparatus having a color image formed by sequentially superimposing a plurality of color toner images on an intermediate transfer body, and secondary-transferring the color image collectively onto a recording material to reduce color misregistration. Good suppressed images are provided. Further, the layout via the intermediate transfer member improves the degree of freedom of the layout in the image forming apparatus, and achieves downsizing of the apparatus, improvement of maintainability, and the like.
[0032]
Further, according to the present invention, there is provided a process cartridge for an image forming apparatus comprising at least one of a charging unit, an exposing unit, a developing unit, and a transferring unit, and the electrophotographic photosensitive member of the present invention.
[0033]
As a result, the electrophotographic photosensitive member and other process members can be easily replaced in a short period of time, so that the time required for maintenance can be shortened and the cost can be reduced. Further, since the process member and the electrophotographic photoreceptor are integrated, there is an advantage that the accuracy of the mounting position is improved.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of the electrophotographic photosensitive member of the present invention, and shows an electrophotographic photosensitive member having a configuration in which a photosensitive layer is provided on a conductive support. FIGS. 2, 3 and 4 show other examples of the configuration of the electrophotographic photosensitive member according to the present invention. FIG. 2 shows a function-separated type electrophotographic photosensitive member in which a photosensitive layer is composed of a charge generation layer (CGL) and a charge transport layer (CTL). FIG. 3 shows a conductive support and a function-separated type electrophotographic photosensitive member. 1 shows an electrophotographic photoreceptor having an undercoat layer between CGL and CTL of a photosensitive layer. FIG. 4 shows an electrophotographic photosensitive member in which a protective layer is further formed on a photosensitive layer of the type shown in FIG. The electrophotographic photoreceptor according to the present invention may have other layers besides the above as long as it has at least the photosensitive layer on the conductive support. May be arbitrarily combined.
[0035]
In the present invention, as the conductive support used for the electrophotographic photoreceptor, a conductor or an insulator subjected to a conductive treatment, for example, metals such as Al, Ni, Fe, Cu, Au, or alloys thereof, and polyester Metal such as Al, Ag, Au or In on an insulating substrate such as polycarbonate, polyimide, glass, etc. _Two O _Three , SnO _Two A resin substrate formed by forming a thin film of a conductive material such as carbon black, graphite, metal powder such as Al, Cu, Ni, or conductive glass powder in a resin, and imparting conductivity to the resin; Conductive treated paper or the like can be used. The shape of the conductive support is not particularly limited, and any of a plate shape, a drum shape, and a belt shape can be used. However, when a belt-shaped support is used, it is necessary to provide a driving roller and a driven roller inside. On the other hand, there are merits such as an increase in the degree of freedom in layout, although the device becomes complicated or large. However, when a protective layer is formed, the flexibility of the protective layer is insufficient, and a crack called a crack may be formed on the surface, which may cause a granular background stain. Can be For this reason, a highly rigid drum-shaped support is preferably used.
[0036]
An undercoat layer may be provided between the conductive support and the photosensitive layer, if necessary. Such an undercoat layer is provided for the purpose of improving adhesiveness, preventing moiré, improving coatability of the upper layer, reducing residual potential, and the like. The undercoat layer generally contains a resin as a main component. However, considering that these resins are coated with a photosensitive layer using a solvent, the resin is a resin having high solubility resistance to a general organic solvent. Desirably. As such a resin, polyvinyl alcohol, casein, water-soluble resin such as sodium polyacrylate, copolymerized nylon, alcohol-soluble resin such as methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, epoxy resin, etc. Curable resins that form a three-dimensional network structure are exemplified. Further, fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide and indium oxide, or metal sulfides and metal nitrides may be added. These undercoat layers can be formed by a commonly used coating method using an appropriate solvent.
[0037]
Further, as such an undercoat layer, a metal oxide layer formed by a sol-gel method or the like using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful.
[0038]
In addition, as such an undercoat layer, Al _Two O _Three Provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), SnO _Two , TiO _Two , ITO, CeO _Two And the like may be provided by a vacuum thin film manufacturing method.
The thickness of the undercoat layer is suitably about 0.1 to 5 μm.
[0039]
As the type of the photosensitive layer used in the electrophotographic photosensitive member of the present invention, any of Se type, OPC type and the like can be applied. Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and the like. In particular, environmentally friendly and inexpensive OPC is good. Of these, the OPC system will be briefly described below.
[0040]
The photosensitive layer in the present invention may be of a single-layer type or a laminated type. Here, the laminated type will be described. First, the charge generation layer will be described.
The charge generation layer is a layer containing a charge generation substance as a main component, and a binder resin may be used as necessary. As the charge generation substance, an inorganic material and an organic material can be used.
[0041]
Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and the like.
On the other hand, as the organic material, a known material can be used. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulhenium salt pigments, methine squaric acid pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyryl carbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.
[0042]
As the binder resin used as needed for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, Polyacrylamide or the like is used. These binder resins can be used alone or as a mixture of two or more.
[0043]
Further, if necessary, a charge transporting substance may be added. Further, as the binder resin for the charge generation layer, a polymer charge transporting substance is preferably used in addition to the binder resin described above.
[0044]
As a method for forming the charge generation layer, a vacuum thin film preparation method and a casting method from a solution dispersion system are mainly mentioned.
Examples of the former method include a glow discharge polymerization method, a vacuum evaporation method, a CVD method, a sputtering method, a reactive sputtering method, an ion plating method, and an accelerated ion injection method. This vacuum thin film manufacturing method can favorably form the above-described inorganic or organic material.
[0045]
Further, in order to provide the charge generation layer by the latter casting method, a ball mill using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, if necessary, together with the above-mentioned inorganic or organic charge generation material as a binder resin, It can be formed by dispersing with an attritor, a sand mill or the like, diluting the dispersion liquid appropriately, and applying. The coating can be performed by a commonly used method such as a dip coating method, a spray coating method or a bead coating method.
[0046]
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, and preferably 0.05 to 2 μm.
[0047]
The charge transport layer is a layer for retaining charged charges and for transferring charges generated and separated in the charge generation layer by exposure to light and combining them with the retained charged charges. In order to achieve the purpose of retaining the charged charge, high electric resistance is required. In addition, in order to achieve the purpose of obtaining a high surface potential with the retained charge, it is required that the dielectric constant is small and the charge mobility is good.
[0048]
The charge transporting layer for satisfying these requirements is composed of a charge transporting substance and a binder resin used as required. Such a charge transporting layer can be formed by dissolving or dispersing the charge transporting substance and the binder resin in an appropriate solvent, and applying and drying this. If necessary, additives such as a plasticizer, an antioxidant, and a leveling agent can be added to the charge transport layer in addition to the charge transport material and the binder resin.
[0049]
As the charge transporting substance, there are a hole transporting substance and an electron transporting substance.
Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4one, 1,3,7-trione An electron accepting substance such as nitrodibenzothiophene-5,5-dioxide is exemplified. These electron transport materials can be used alone or as a mixture of two or more.
[0050]
Examples of the hole transport material include the electron donating materials shown below and are preferably used. For example, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline Phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives and the like. These hole transport materials can be used alone or as a mixture of two or more.
[0051]
Further, the polymer charge transporting substance may have the following structure.
(A) Polymer having a carbazole ring
For example, poly-N-vinylcarbazole, JP-A-50-82056, JP-A-54-9632, JP-A-54-11737, JP-A-4-175337, JP-A-4-183719 And the compounds described in JP-A-6-234841.
[0052]
(B) Polymer having a hydrazone structure
For example, JP-A-57-78402, JP-A-61-20953, JP-A-61-296358, JP-A-1-134456, JP-A-1-179164, and JP-A-3-180851 And the compounds described in JP-A-3-180852, JP-A-3-50555, JP-A-5-310904, and JP-A-6-234840.
[0053]
(C) Polysilylene polymer
For example, JP-A-63-285552, JP-A-1-88461, JP-A-4-264130, JP-A-4-264131, JP-A-4-264132, JP-A-4-264133. And the compounds described in JP-A-4-289867.
[0054]
(D) Polymer having triarylamine structure
For example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-134457, JP-A-2-282264, JP-A-2-304456, JP-A-4-1330065 And the compounds described in JP-A-4-133066, JP-A-5-40350, and JP-A-5-202135.
[0055]
(E) Other polymers
For example, the compounds described in formaldehyde polycondensate of nitropyrene, JP-A-51-73888, JP-A-56-150749, JP-A-6-234836, and JP-A-6-234837 are exemplified. You.
[0056]
The polymer having an electron donating group used in the present invention includes not only the above-mentioned polymer but also a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, and, for example, It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-3-109406.
[0057]
Further, polycarbonates, polyurethanes, polyesters and polyethers having a triarylamine structure which are more useful as the polymer charge transporting substance used in the present invention include, for example, JP-A-64-1728 and JP-A-64-128. 13061, JP-A-64-19049, JP-A-4-11627, JP-A-4-225014, JP-A-4-230767, JP-A-4-320420, JP-A-5-232727 JP-A-7-56374, JP-A-9-127713, JP-A-9-222740, JP-A-9-265197, JP-A-9-212877, JP-A-9-304957 And the like.
[0058]
Further, as a binder resin that can be used in combination with the charge transport layer, for example, polycarbonate, polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenolic resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, Silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyacrylate, polyacrylamide, phenoxy resin and the like are used. These binder resins can be used alone or as a mixture of two or more.
[0059]
The thickness of the charge transport layer is suitably about 5 to 100 μm. However, in recent years, demands for higher image quality have made it possible to reduce the thickness of the charge transport layer, achieving higher image quality of 1200 dpi or more. In order to do so, the thickness is more preferably about 5 to 30 μm.
[0060]
In the charge transport layer of the present invention, other additives such as antioxidants and plasticizers used for rubber, plastics, fats and the like may be added.
Further, a leveling agent may be added to the charge transport layer. As such a leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used, and the amount of use is based on 100 parts by weight of the binder resin. Thus, 0 to 1 part by weight is appropriate.
[0061]
As a coating method, a commonly used method such as a dip coating method, a spray coating method, a bead coating method, or the like can be used.
[0062]
Further, when the charge transport layer is the outermost layer of the photoreceptor, at least the charge transport layer contains lanolin or a derivative thereof.
As represented by the following formula, lanolin has a structure in which a chain hydrocarbon group is bonded to a steroid structure and various fatty acid moieties are bonded via an ester bond, so that the bulkier hydrocarbon is It has a part. Therefore, it is considered that the effect of reducing the friction coefficient is large. Further, by changing the fatty acid site, a variety of chemical properties such as solubility in an organic solvent and a melting point can be imparted. Moreover, since lanolin is easily produced from natural products, it is inexpensive and can be said to have higher cost performance than, for example, a lubricant such as a fluororesin.
[0063]
Embedded image

[0064]
When these lanolins or derivatives thereof are contained in the charge transport layer, it is preferable to increase the content near the surface of the charge transport layer in order to more efficiently obtain the effect of reducing the friction coefficient. That is, since lanolin or its derivative present on the surface of the photoreceptor exerts the effect of reducing the friction coefficient, lanolin or its derivative contained inside the surface of the charge transport layer is wasted, and conversely. The electrophotographic properties of the photoconductor may be adversely affected. As a method for producing an electrophotographic photoreceptor containing a large amount of lanolin or a derivative thereof near the surface of the charge transport layer, for example, a plurality of coating liquids for forming a charge transport layer having different contents of lanolin or a derivative thereof are prepared and contained. A method such as applying the liquid in order from a small amount is conceivable.
[0065]
For example, first, a first charge transport layer is formed on a charge generation layer using a charge transport layer-forming coating solution containing no lanolin or a derivative thereof, and the content of lanolin or a derivative thereof is reduced to 50% from above. The second charge transporting layer is formed using the coating liquid for forming a charge transporting layer described above, and dried to form a charge transporting layer containing a large amount of lanolin or a derivative thereof on the surface.
The coating method is not limited to dip coating, but may be a known method such as spray coating.
[0066]
The content of lanolin or a derivative thereof is preferably in the range of 1 to 75 wt% of the total solids in the outermost layer. If the amount is less than 1 wt%, the effect of reducing the friction coefficient becomes insufficient, and the various effects described above cannot be obtained.
If the content is more than 75% by weight, lanolin or a derivative thereof itself has a low film-forming property, so that a good coating film cannot be obtained, or the electrical characteristics of the photoconductor become poor, such as an increase in residual potential or photosensitivity. May cause a decrease in
[0067]
When the charge transport layer is the outermost layer, the photoreceptor of the present invention may contain a filler in the charge transport layer.
As the filler material, there are an organic filler material and an inorganic filler material. Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, and a-carbon powder.Examples of the inorganic filler material include copper, tin, aluminum, and metal powders such as indium. Metal oxides such as silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide, tin-doped indium oxide, tin fluoride, fluoride Examples include inorganic materials such as metal fluorides such as calcium and aluminum fluoride, potassium titanate, and boron nitride.
[0068]
Since the filler made of an inorganic material has higher hardness than the filler made of an organic material, the wear resistance of the outermost layer of the photoconductor can be further improved. However, generally, when the wear resistance of the latent image carrier is improved, the surface portion of the latent image carrier hardly wears, but the surface portion of the latent image carrier is reacted with a reactive gas such as ozone or NOx generated during charging. It is known that the resistance is reduced, the electrostatic charge on the surface gradually stops being held, and the electrostatic charge moves toward the surface. As a result, the electrostatic latent image bleeds, and an abnormal image called image blur or image deletion which occurs when the electrostatic latent image is developed with toner or the like occurs. Therefore, as the filler used in the present invention, 10 ^Ten It is preferable to have a high resistance of Ωcm or more. By using such a filler, the lowering of the resistance of the outermost layer of the latent image carrier is suppressed, and the occurrence of the abnormal image can be significantly suppressed.
[0069]
Among these fillers, silica, titanium oxide and alumina can be effectively used. Further, since these filler materials are inexpensive and easily available as compared with other metal oxide fine particles, the production cost of the latent image carrier can be reduced.
Among them, α-alumina, which has high insulation properties, high thermal stability, and has high wear resistance, and is a hexagonal close-packed structure, is particularly useful in terms of suppressing image blur and improving wear resistance. . Such filler materials may be used alone or in combination of two or more.
[0070]
These filler materials can be dispersed together with a charge transport substance, a binder resin, a solvent, and the like by using an appropriate disperser. The average primary particle size of the filler is 0.05 to 1.0 μm, preferably 0.1 to 0.3 μm.
If the average primary particle size of the filler is less than 0.05 μm, the abrasion resistance may be insufficient. On the other hand, when the average primary particle size of the filler is too large than 1.0 μm, the optical writing light applied to the latent image carrier is scattered by the filler and the transmittance is reduced, which causes image blur and thick characters. Sometimes.
[0071]
The filler concentration in the surface layer varies depending on the kind of filler used and the electrophotographic process conditions using the photoreceptor, but is preferably 5 to 60% by weight. It is also possible to include these fillers in the entire charge transport layer.However, since the potential of the exposed portion may increase, the outermost surface of the charge transport layer has the highest filler content, and the conductive support It is preferable to provide a filler concentration gradient so that the body side becomes lower, or a structure in which a plurality of charge transport layers are provided so that the filler concentration gradually increases from the conductive support side toward the surface side.
[0072]
Next, a case where the photosensitive layer has a single-layer structure will be described.
When a single-layer photosensitive layer is provided by a casting method, in many cases, such a single-layer photosensitive layer is prepared by dissolving or dispersing a charge-generating substance, a low-molecular-weight substance, and a high-molecular-weight charge-transporting substance in an appropriate solvent, coating and drying the same. Can be formed. As the charge generating substance and the charge transporting substance, the above-described materials can be used.
[0073]
If necessary, a plasticizer can be added to the single-layer photosensitive layer. Further, as the binder resin that can be used as needed, the binder resin described above for the charge transport layer can be used as it is. In addition, the binder resins mentioned for the charge generation layer may be mixed and used.
[0074]
Further, when the single-layer photosensitive layer is the outermost layer of the photoconductor, at least the single-layer photosensitive layer contains lanolin or a derivative thereof.
Thereby, the same effect as in the case where lanolin or a derivative thereof is contained in the above-described charge transport layer can be obtained.
[0075]
Further, similarly to the case where lanolin or a derivative thereof is contained in the above-mentioned charge transport layer, it is preferable to increase the content of lanolin or a derivative thereof near the surface, and a similar manufacturing method can be used.
The thickness of the photosensitive layer of the single-layer photosensitive member is suitably about 5 to 100 μm.
[0076]
In the photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer. Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, aryl resin, phenolic resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, polyarylate, AS resin, butadiene-styrene copolymer, polyurethane, polychloride Resins such as vinyl, polyvinylidene chloride, and epoxy resin are exemplified.
[0077]
When a protective layer is used, lanolin or a derivative thereof is contained in the protective layer because the protective layer is the outermost layer. The protective layer mainly aims at improving abrasion resistance. In the present invention, by containing lanolin or a derivative thereof, the friction coefficient is reduced, and the wear resistance is improved. Furthermore, since the protective layer is provided on the photosensitive layer with a relatively small thickness, the influence on the electrical characteristics of the photoreceptor is relatively small, and the content of the charge transport layer is lower than that in the case where lanolin or a derivative thereof is contained. Can be increased. Therefore, by further containing lanolin or a derivative thereof in the protective layer, a further reduction in the coefficient of friction can be achieved.
[0078]
Further, the protective layer may contain a filler material in order to impart further wear resistance. As the filler, those described above can be used, and these filler materials are used alone or in combination of two or more.
[0079]
Including a charge transport material in the protective layer is also very useful for suppressing the electrical characteristics of the photoreceptor, in particular, the deterioration of photosensitivity during repeated use and the increase in residual potential. This is because the charge can be smoothly transferred to the surface of the photoreceptor by providing the protective layer with the charge transport property. As the charge transporting substance, the charge transporting substances used in the charge transporting layer described above can be used.
[0080]
Further, various additives may be added to the protective layer of the electrophotographic photosensitive member according to the present invention for the purpose of improving adhesiveness, smoothness, and chemical stability.
[0081]
The protective layer according to the present invention is formed on the photosensitive layer using a conventional coating method such as dip coating, spray coating, blade coating, and knife coating. In particular, dip coating and spray coating are advantageous in terms of mass productivity and coating film quality.
The thickness of the protective layer is suitably in the range of 0.1 to 10 μm.
[0082]
Next, the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 5 is a schematic diagram for explaining the image forming apparatus of the present invention. The following modifications also belong to the category of the present invention.
As shown in FIG. 5, the image forming apparatus using the electrophotographic photosensitive member according to the present invention includes a drum-shaped photosensitive member 1, a charging charger 3, a pre-transfer charger 7, a transfer charger 10 according to the present invention. , A separation charger 11, a pre-cleaning charger 13, and the like. The shape of the photoconductor 1 is not limited to a drum shape, but may be, for example, a sheet shape or an endless belt shape. As the various chargers, known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller can be used.
As the transfer means, generally, the above-mentioned charger can be used. However, a combination of a transfer charger and a separation charger as shown in the figure is effective.
[0083]
Light sources such as the image exposure unit 5 and the static elimination lamp 2 include light sources such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). All things can be used. To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used.
Such a light source or the like can irradiate the photoreceptor with light by providing a transfer step using light irradiation in combination with a step shown in FIG. 5, a charge removal step, a cleaning step, or a pre-exposure step. .
[0084]
Now, the toner developed on the photoconductor 1 by the developing unit 6 is transferred to the transfer paper 9, but not all is transferred, and the toner remains on the photoconductor 1. Such toner is removed from the photoconductor by the cleaning brush 14 and the blade 15. The cleaning may be performed by a cleaning brush or a blade alone, and a known cleaning brush such as a fur brush or a mag fur brush is used.
[0085]
When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with a negative (positive) polarity toner (electrostatic detection fine particles), a positive image can be obtained, and if it is developed with a positive (negative) polarity toner, a negative image can be obtained. A known method is applied as such a developing unit, and a known method is also used as the charge removing unit.
[0086]
FIG. 6 shows an example of another process using the image forming apparatus according to the present invention. In FIG. 6, a photoconductor 22 is an electrophotographic photoconductor of the present invention, is driven by a driving roller 23, and is charged by a charging charger 20, image exposure by a light source 21, development (not shown), and uses a charger 25. Transfer, cleaning by the brush 26, and charge elimination by the light source 27 are repeatedly performed.
[0087]
Further, an embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described as a full-color image forming apparatus to which the present invention is applied.
FIG. 7 is a schematic configuration diagram of the printer according to the present embodiment. In the figure, a photosensitive member 56 as a latent image carrier is rotated and driven counterclockwise in the figure, and the surface thereof is uniformly charged by a charging charger 53 using a corotron or a scorotron. To carry an electrostatic latent image by scanning with a laser beam L emitted from the laser beam. Since this scanning is performed based on single-color image information obtained by decomposing a full-color image into yellow, magenta, cyan, and black color information, a single-color electrostatic image of yellow, magenta, cyan, or black is formed on the photosensitive drum 56. A latent image is formed. A revolver developing unit 50 is provided on the left side of the photosensitive drum 56 in the drawing. This has a yellow developing device, a magenta developing device, a cyan developing device, and a black developing device in a rotating drum-shaped housing, and sequentially rotates each developing device to a developing position opposed to the photosensitive drum 56 by rotation. Move. The yellow developing device, the magenta developing device, the cyan developing device, and the black developing device develop an electrostatic latent image by attaching yellow toner, magenta toner, cyan toner, and black toner, respectively. On the photosensitive drum 56, electrostatic latent images for yellow, magenta, cyan, and black are sequentially formed, and these are sequentially developed by the respective developing units of the revolver developing unit 50 to form a yellow toner image, a magenta toner image, and a cyan toner image. It becomes a toner image and a black toner image.
[0088]
An intermediate transfer unit is provided downstream of the developing position of the photosensitive drum 56. This is because the intermediate transfer belt 58 stretched by the tension roller 59a, the intermediate transfer bias roller 57 as a transfer means, the secondary transfer backup roller 59b, and the belt drive roller 59c is rotated by the belt drive roller 59c in the figure. Move endlessly clockwise. The yellow toner image, magenta toner image, cyan toner image, and black toner image developed on the photosensitive drum 56 enter the intermediate transfer nip where the photosensitive drum 56 and the intermediate transfer belt 58 are in contact. Then, under the influence of the bias from the intermediate transfer bias roller 57, the image is superimposed and intermediately transferred onto the intermediate transfer belt 58 to form a four-color superimposed toner image.
[0089]
The surface of the photosensitive drum 56 that has passed through the intermediate transfer nip with the rotation is cleaned by the drum cleaning unit 55 to remove the transfer residual toner. The cleaning unit 55 cleans transfer residual toner with a cleaning roller to which a cleaning bias is applied, but may use a cleaning brush such as a fur brush or a mag fur brush, or a cleaning blade.
[0090]
The surface of the photosensitive drum 56 from which the transfer residual toner has been cleaned is discharged by the discharge lamp 54. As the charge removing lamp 54, a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), or the like is used. A semiconductor laser is used as a light source of the laser optical device. With respect to the emitted light, only a desired wavelength range may be used by various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter.
[0091]
On the lower side of the intermediate transfer unit in the figure, a transfer unit including a transfer belt, a transfer bias roller, and various rollers such as a drive roller is provided. On the left side of the figure, a transport belt 64 and a fixing unit 65 are provided. It is arranged. In the transfer unit, the transfer belt that moves endlessly may be moved in the vertical direction in the figure by moving means (not shown), and at least a one-color toner image (yellow toner image) on the intermediate transfer belt 58, When the two-color or three-color superimposed toner image passes through a position facing the paper transfer bias roller 63, the toner image is retracted to a position where it does not contact the intermediate transfer belt 58. Before the leading end of the four-color superimposed toner image on the intermediate transfer belt 58 enters the position facing the paper transfer bias roller 63, the toner image moves to the contact position with the intermediate transfer belt 58 and the secondary transfer nip is formed. To form
[0092]
On the other hand, a pair of registration rollers 61 that sandwich the transfer paper 60 sent from a paper feed cassette (not shown) between the two rollers can superimpose the transfer paper 60 on the four-color superimposed toner image on the intermediate transfer belt 58. It is fed at the timing toward the secondary transfer nip. The four-color superimposed toner image on the intermediate transfer belt 58 is secondarily transferred collectively onto the transfer paper P in the secondary transfer nip under the influence of the secondary transfer bias from the paper transfer bias roller 63. By this secondary transfer, a full-color image is formed on the transfer paper 60.
[0093]
The transfer paper 60 on which the full-color image has been formed is sent to the paper transport belt 64 by the transfer belt 62.
The transport belt 64 sends the transfer paper 60 received from the transfer unit into the fixing unit 65.
The fixing unit 65 conveys the transferred transfer paper 60 while nipping the transfer paper 60 into a fixing nip formed by contact between the heating roller and the backup roller.
The full-color image on the transfer paper 60 is fixed on the transfer paper 60 under the influence of the heating from the heating roller and the pressing force in the fixing nip.
[0094]
Although not shown, a bias for adsorbing the transfer paper P is applied to the transfer belt 62 and the transport belt 64. Further, a paper discharging charger for discharging the transfer paper 60 and three belt discharging chargers for discharging the respective belts (the intermediate transfer belt 58, the transfer belt 62, and the transport belt 64) are provided. The intermediate transfer unit also includes a belt cleaning unit having the same configuration as the drum cleaning unit 55, and thereby cleans the transfer residual toner on the intermediate transfer belt 58.
[0095]
FIG. 8 is a modified example of the printer according to the present embodiment. This device is a so-called tandem type printer, and includes photoconductor drums 80Y, 80M, 80C, and 80Bk for each color, instead of sharing the photoconductor drum 80 with each color. The drum cleaning unit 85, the discharging lamp 83, and the charging roller 84 for uniformly charging the drum are also provided for each color. In the printer shown in FIG. 7, the charging charger 53 is provided as drum uniform charging means, but in this printer, a charging roller 84 is provided.
In the tandem system, since the formation and development of latent images of each color can be performed in parallel, the image forming speed can be much higher than in the revolver system.
[0096]
【Example】
Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to the following Examples.
[0097]
Example 1
15 parts by weight of an alkyd resin (Beccolite M6401-50 (manufactured by Dainippon Ink and Chemicals, Inc.)) and 10 parts by weight of melamine resin (Super Beckamine G-821-60 (manufactured by Dainippon Ink and Chemicals, Inc.)) are used. And 90 parts by weight of titanium oxide powder (Taipal CR-EL (manufactured by Ishihara Sangyo Co., Ltd.)) was added thereto and dispersed by a ball mill for 12 hours to prepare a coating liquid for an undercoat layer.
This was coated on a cylindrical aluminum substrate having a diameter of 30 mm by a dip coating method and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 3.5 μm.
[0098]
Next, 4 parts by weight of a polyvinyl butyral resin (XYHL (manufactured by UCC)) was dissolved in 150 parts by weight of cyclohexanone, 10 parts by weight of a bisazo pigment represented by the following structural formula (1) was added, and the mixture was dispersed by a ball mill for 48 hours. Further, 210 parts by weight of cyclohexanone was added and dispersed for 3 hours. This was taken out into a container and diluted with cyclohexanone so that the solid content was 1.5% by weight. The coating liquid for a charge generation layer thus obtained was coated on the intermediate layer and dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.2 μm. .
[0099]
Embedded image

[0100]
Next, 10 parts by weight of a bisphenol Z-type polycarbonate resin and 0.002 parts by weight of silicone oil (KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)) are dissolved in 100 parts by weight of tetrahydrofuran. A charge transport layer coating liquid was prepared by adding 10 parts by weight of the charge transport material. The charge transport layer coating solution thus obtained was applied onto the charge generation layer by dip coating, and then dried at 110 ° C. for 20 minutes to form a charge transport layer having a thickness of 20 μm.
[0101]
Embedded image

[0102]
Next, in a mixed solvent of 280 parts by weight of tetrahydrofuran and 80 parts by weight of cyclohexanone, 3 parts by weight of purified lanolin (trade name: Lanolin TR manufactured by Nippon Seika Co., Ltd.) and 7 parts by weight of a bisphenol Z-type polycarbonate resin are dissolved to form a protective layer. A coating solution was prepared. The thus-obtained coating liquid for forming a protective layer was applied onto the charge transport layer by a spray coating method, and then dried at 130 ° C. for 20 minutes to form a protective layer having a thickness of 6 μm, thereby producing an electrophotographic photoreceptor.
[0103]
Example 2
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that lanolin fatty acid metal soap (trade name: Neocoat OF-3301 manufactured by Nippon Seika) was used instead of purified lanolin.
[0104]
Example 3
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that lanolin fatty acid polyhydric alcohol ester (trade name: Neocoat EP-2 manufactured by Nippon Seika) was used instead of purified lanolin.
[0105]
Example 4
Same as Example 1 except that 7 parts by weight of bisphenol Z-type polycarbonate resin and 3 parts by weight of purified lanolin used for the protective layer were changed to 9.5 parts by weight of bisphenol Z-type polycarbonate resin and 0.5 parts by weight of purified lanolin. Thus, an electrophotographic photosensitive member was manufactured.
[0106]
Example 5
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 7 parts by weight of bisphenol Z-type polycarbonate resin and 3 parts by weight of purified lanolin used in the protective layer were changed to 3 parts by weight of bisphenol Z-type polycarbonate resin and 7 parts by weight of purified lanolin. The body was made.
[0107]
Example 6
The same procedure as in Example 1 was carried out except that 7 parts by weight of the bisphenol Z-type polycarbonate resin used for the protective layer was changed to 4 parts by weight of the bisphenol Z-type polycarbonate resin, and 3 parts by weight of the charge transport material of the structural formula (2) was further added. Thus, an electrophotographic photosensitive member was produced.
[0108]
Example 7
Instead of the coating solution for the protective layer used in Example 1, a mixed solvent of 80 parts by weight of tetrahydrofuran and 280 parts by weight of cyclohexanone was added to 4 parts by weight of a bisphenol Z-type polycarbonate resin, and 3 parts by weight of the charge transport material of the structural formula (2). And 3 parts by weight of purified lanolin, and 0.2 parts by weight of alumina fine particles (average particle size: 0.3 μm) were added thereto, and the resulting mixture was dispersed in a ball mill for 2 hours. Except for the above, an electrophotographic photosensitive member was produced in the same manner as in Example 1.
[0109]
Example 8
An electrophotographic photosensitive member was produced in the same manner as in Example 7, except that silica fine particles (average particle diameter: 0.3 μm) were used instead of alumina fine particles.
[0110]
Comparative Example 1
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that purified lanolin was not added to the coating liquid for forming a protective layer.
[0111]
Comparative Example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 7, except that purified lanolin was not added to the coating liquid for forming a protective layer.
[0112]
Comparative Example 3
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that fine particles of ethylene tetrafluoride resin (trade name: Lubron L-2 manufactured by Daikin Industries, Ltd.) were used instead of purified lanolin. Ethylene fine particles aggregated and precipitated in the coating solution. Further, the surface of the protective layer coating film formed by spray coating while stirring the coating liquid became rough.
[0113]
Comparative Example 4
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 0.035 parts by weight of silicone oil (trade name: KF-50 manufactured by Shin-Etsu Chemical Co., Ltd.) was added instead of purified lanolin.
[0114]
The photoreceptor thus obtained is mounted on a copying machine equipped with the image forming engine shown in FIG. 8 and having a copy speed of 60 sheets / min (A4 portrait), and charged so that the non-exposed portion potential (VD) becomes -700 V. After adjusting the voltage of the container, a running test for outputting a test image having an A4 size and an image area ratio of 5% by writing at 600 dpi was performed on 50,000 sheets. From the difference in the thickness of the photosensitive layer before and after the running test, The amount of wear was measured. The film thickness was measured using an eddy current film thickness meter Fischerscope MMS (manufactured by Fischer). Further, an initial image before the running test and a durable image after the running test were output, and the image quality was also evaluated.
[0115]
Further, in the above-described copying machine, the contact pressure of the cleaning blade, the nip of the developing sleeve, the additive of the toner to be used, and the like are adjusted so that a greater load is applied to the wear of the photoconductor.
Table 1 summarizes the results of these image evaluations and wear amount measurements.
[0116]
[Table 1]

[0117]
【The invention's effect】
As described above, as apparent from the detailed and specific description, the present invention relates to an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, in which at least lanolin or a derivative thereof is present on the outermost layer of the photosensitive layer. As a result, the coefficient of friction of the surface can be reduced, and as a result, abnormal images such as worm prints and poor cleaning can be significantly reduced. In addition, since lanolin or a derivative thereof is easily dissolved or dispersed in an organic solvent, the stability of the coating liquid is high, and a good coating film can be obtained. Further, since the abrasion resistance is improved, even when used repeatedly for a long time, the above-mentioned abnormal image does not occur and a good image is stably output. This provides an extremely excellent effect of providing a full-color image forming apparatus and a process cartridge for the image forming apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating an example of a layer configuration of an electrophotographic photoreceptor of the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 3 is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 4 is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 5 is a schematic view of an example of the image forming apparatus of the present invention.
FIG. 6 is a schematic view illustrating another process of the image forming apparatus of the present invention.
FIG. 7 is a schematic configuration diagram of a printer which is an example of the image forming apparatus of the present invention.
FIG. 8 is a schematic configuration diagram of a modified example of a printer which is an example of the image forming apparatus of the present invention.

Claims (15)

An electrophotographic photoreceptor having at least a laminated or single-layered photosensitive layer on a conductive support, wherein the outermost layer of the photosensitive layer contains at least lanolin or a derivative thereof. The electrophotographic photosensitive member according to claim 1, wherein the lanolin or a derivative thereof is contained in the outermost layer in an amount of 1 to 75 wt%. The photosensitive layer comprises at least a layer containing a charge generating substance and a charge transporting substance, and a protective layer laminated thereon, wherein the protective layer is the outermost layer containing lanolin or a derivative thereof. The electrophotographic photoreceptor according to claim 1 or 2, wherein The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the outermost layer contains at least fine particles as a filler. The electrophotographic photosensitive member according to claim 4, wherein the content of the filler is 5 to 60 wt% of the outermost layer. The electrophotographic photosensitive member according to claim 4, wherein the filler contains at least metal oxide fine particles as the filler. The electrophotographic photoreceptor according to any one of claims 4 to 6, wherein the filler has an average primary particle size of 0.05 to 1.0 µm. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the outermost layer contains at least a charge transport material. An image forming apparatus having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, and a transfer unit, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 8. Forming equipment. The image forming apparatus according to claim 9, wherein the image forming apparatus is a tandem type having a plurality of electrophotographic photosensitive members, a charging unit, a developing unit, and a transfer unit. An image having an intermediate transfer unit for performing a primary transfer of the toner image developed on the electrophotographic photosensitive member onto the intermediate transfer member by the image forming apparatus and then secondary transferring the toner image on the intermediate transfer member onto a recording material 10. A forming apparatus, wherein a color image is formed by sequentially superimposing a plurality of color toner images on an intermediate transfer member, and the color image is secondarily transferred collectively to a recording material. An image forming apparatus according to claim 10. The surface of the electrophotographic photosensitive member is charged with an electrostatic charge by a charging unit, an image is exposed by an exposing unit, an electrostatic latent image is formed on the surface of the photoreceptor, a visible image is formed by a developing unit, and the image is formed by a transferring unit. An image forming method for transferring a visible image to a transfer material, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 8. 13. The image forming method according to claim 12, wherein the image forming method uses a tandem image forming apparatus having a plurality of electrophotographic photosensitive members, a charging unit, a developing unit, and a transfer unit. An image having an intermediate transfer means for performing a primary transfer of a toner image developed on an electrophotographic photosensitive member to an intermediate transfer member by the image forming method and then secondary transferring the toner image on the intermediate transfer member to a recording material 14. The image forming apparatus according to claim 12, wherein a plurality of color toner images are sequentially superimposed on the intermediate transfer body to form a color image, and the color image is collectively secondary-transferred onto a recording material. 2. The image forming method according to 1., The process cartridge for an image forming apparatus according to claim 9, further comprising at least one of a charging unit, an exposing unit, a developing unit, and a transferring unit, and an electrophotographic photosensitive member.

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