JP3717692B2 - Coating liquid for photosensitive layer, electrophotographic photosensitive member, electrophotographic method, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Description

式中、Ｒ₁，Ｒ₂，Ｒ₃はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ₄は水素原子又は置換もしくは無置換のアルキル基、Ｒ₅，Ｒ₆は置換もしくは無置換のアリール基、ｏ，ｐ，ｑはそれぞれ独立して０〜４の整数、ｋ，ｊは組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表し５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表される２価基を表す。
【化２】

式中、Ｒ₁₀₁，Ｒ₁₀₂は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表す。ｌ，ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−，−Ｓ−，−ＳＯ−，−ＳＯ₂−，−ＣＯ−，−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表す。）または、
【化３】

式中、ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ₁₀₃、Ｒ₁₀₄は置換または無置換のアルキル基又はアリール基を表す。ここで、Ｒ₁₀₁とＲ₁₀₂，Ｒ₁₀₃とＲ₁₀₄は、それぞれ同一でも異なってもよい。
【００４７】
【化４】

式中、Ｒ₇，Ｒ₈は置換もしくは無置換のアリール基、Ａｒ₁，Ａｒ₂，Ａｒ₃は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００４８】
【化５】

式中、Ｒ₉，Ｒ₁₀は置換もしくは無置換のアリール基、Ａｒ₄，Ａｒ₅，Ａｒ₆は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００４９】
【化６】

式中、Ｒ₁₁，Ｒ₁₂は置換もしくは無置換のアリール基、Ａｒ₇，Ａｒ₈，Ａｒ₉は同一又は異なるアリレン基、ｐは１〜５の整数を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５０】
【化７】

式中、Ｒ₁₃，Ｒ₁₄は置換もしくは無置換のアリール基、Ａｒ₁₀，Ａｒ₁₁，Ａｒ₁₂は同一又は異なるアリレン基、Ｘ₁，Ｘ₂は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５１】
【化８】

式中、Ｒ₁₅，Ｒ₁₆，Ｒ₁₇，Ｒ₁₈は置換もしくは無置換のアリール基、Ａｒ₁₃，Ａｒ₁₄，Ａｒ₁₅，Ａｒ₁₆は同一又は異なるアリレン基、Ｙ₁，Ｙ₂，Ｙ₃は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表し同一であっても異なっていてもよい。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５２】
【化９】

式中、Ｒ₁₉，Ｒ₂₀は水素原子、置換もしくは無置換のアリール基を表し、Ｒ₁₉とＲ₂₀は環を形成していてもよい。Ａｒ₁₇，Ａｒ₁₈，Ａｒ₁₉は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５３】
【化１０】

式中、Ｒ₂₁は置換もしくは無置換のアリール基、Ａｒ₂₀，Ａｒ₂₁，Ａｒ₂₂，Ａｒ₂₃は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５４】
【化１１】

式中、Ｒ₂₂，Ｒ₂₃，Ｒ₂₄，Ｒ₂₅は置換もしくは無置換のアリール基、Ａｒ₂₄，Ａｒ₂₅，Ａｒ₂₆，Ａｒ₂₇，Ａｒ₂₈は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５５】
【化１２】

式中、Ｒ₂₆，Ｒ₂₇は置換もしくは無置換のアリール基、Ａｒ₂₉，Ａｒ₃₀，Ａｒ₃₁は同一又は異なるアリレン基を表す。Ｘ，ｋ，ｊおよびｎは、（１）式の場合と同じである。
【００５６】
本発明において電荷輸送層３７中に可塑剤やレベリング剤を添加してもよい。可塑剤としては、ジブチルフタレート、ジオクチルフタレートなど一般の樹脂の可塑剤として使用されているものがそのまま使用でき、その使用量は、結着樹脂に対して０〜３０重量％程度が適当である、レベリング剤としては、ジメチルシリコーンオイル、メチルフェニルシリコーンオイルなどのシリコーンオイル類や、側鎖にパーフルオロアルキル基を有するポリマーあるいはオリゴマーが使用され、その使用量は結着樹脂に対して０〜１重量％が適当である。
【００５７】
次に感光層が単層構成３３の場合について述べる。単層感光層は、電荷発生物質、電荷輸送物質および結着樹脂を適当な溶剤に上述の方法により分散し、これを塗布、乾燥することによって形成できる。さらに、この感光層には上述した電荷輸送材料を添加した機能分離タイプとしても良く、良好に使用できる。また、必要により、可塑剤やレベリング剤、酸化防止剤等を添加することもできる。
【００５８】
結着樹脂としては、先に電荷輸送層３７で挙げた結着樹脂をそのまま用いるほかに、電荷発生層３５で挙げた結着樹脂を混合して用いてもよい。もちろん、先に挙げた高分子電荷輸送物質も良好に使用できる。結着樹脂１００重量部に対する、電荷発生物質の量は５〜４０重量部が好ましく、電荷輸送物質の量は０〜１９０重量部が好ましくさらに好ましくは５０〜１５０重量部である。単層感光層は、電荷発生物質、結着樹脂を必要ならば電荷輸送物質とともにテトラヒドロフラン、ジオキサン、ジクロロエタン、シクロヘキサン等の溶媒を用いて分散機等で分散した塗工液を、浸漬塗工法やスプレーコート、ビードコートなどで塗工して形成できる。単層感光層の膜厚は５〜１００μｍ程度が適当である。
【００５９】
本発明の電子写真感光体には、導電性支持体３１と感光層との間に下引き層を設けることができる。下引き層は一般には樹脂を主成分とするが、これらの樹脂はその上に感光層を溶剤で塗布することを考えると、一般の有機溶剤に対して耐溶剤性の高い樹脂であることが望ましい。このような樹脂としては、ポリビニルアルコール、カゼイン、ポリアクリル酸ナトリウム等の水溶性樹脂、共重合ナイロン、メトキシメチル化ナイロン等のアルコール可溶性樹脂、ポリウレタン、メラミン樹脂、フェノール樹脂、アルキッド−メラミン樹脂、エポキシ樹脂等、三次元網目構造を形成する硬化型樹脂等が挙げられる。また、下引き層にはモアレ防止、残留電位の低減等のために酸化チタン、シリカ、アルミナ、酸化ジルコニウム、酸化スズ、酸化インジウム等で例示できる金属酸化物の微粉末顔料を加えてもよい。
【００６０】
これらの下引き層は前述の感光層の如く適当な溶媒、塗工法を用いて形成することができる。更に本発明の下引き層として、シランカップリング剤、チタンカップリング剤、クロムカップリング剤等を使用することもできる。この他、本発明の下引き層には、Ａ１₂Ｏ₃を陽極酸化にて設けたものや、ポリパラキシリレン（パリレン）等の有機物やＳｉＯ₂，ＳｎＯ₂，ＴｉＯ₂，ＩＴＯ，ＣｅＯ₂等の無機物を真空薄膜作成法にて設けたものも良好に使用できる。このほかにも公知のものを用いることができる。下引き層の膜厚は０〜５μｍが適当である。
【００６１】
本発明の電子写真感光体には、感光層保護の目的で、保護層が感光層の上に設けられることもある。保護層に使用される材料としてはＡＢＳ樹脂、ＡＣＳ樹脂、オレフィン−ビニルモノマー共重合体、塩素化ポリエーテル、アリル樹脂、フェノール樹脂、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアクリレート、ポリアリルスルホン、ポリブチレン、ポリブチレンテレフタレート、ポリカーボネート、ポリエーテルスルホン、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、ポリメチルペンテン、ポリプロピレン、ポリフェニレンオキシド、ポリスルホン、ポリスチレン、ＡＳ樹脂、ブタジエン−スチレン共重合体、ポリウレタン、ポリ塩化ビニル、ポリ塩化ビニリデン、エポキシ樹脂等の樹脂が挙げられる。保護層にはその他、耐摩耗性を向上する目的でポリテトラフルオロエチレンのような弗素樹脂、シリコーン樹脂、及びこれらの樹脂に酸化チタン、酸化錫、チタン酸カリウム等の無機材料を分散したもの等を添加することができる。保護層の形成法としては通常の塗布法が採用される、なお保護層の厚さは０．１〜１０μｍ程度が適当である。また、以上のほかに真空薄膜作成法にて形成したａ−Ｃ，ａ−ＳｉＣなど公知の材料を保護層として用いることができる。
【００６２】
本発明においては感光層と保護層との間に中間層を設けることも可能である。中間層には、一般にバインダー樹脂を主成分として用いる。これら樹脂としては、ポリアミド、アルコール可溶性ナイロン、水溶性ポリビニルブチラール、ポリビニルブチラール、ポリビニルアルコールなどが挙げられる。中間層の形成法としては、前述のごとく通常の塗布法が採用される。なお、中間層の厚さは０．０５〜２μｍ程度が適当である。
【００６３】
次に図面を用いて本発明の電子写真方法ならびに電子写真装置を詳しく説明する。
【００６４】
図５は、本発明の電子写真プロセスおよび電子写真装置を説明するための概略図であり、下記するような変形例も本発明の範疇に属するものである。
【００６５】
図５において、感光体１は導電性支持体上に前述の方法により作製された分散液を用いて製膜した感光層が設けられてなる。感光体１はドラム状の形状を示しているが、シート状、エンドレスベルト状のものであっても良い。帯電チャージャー３、転写前チャージャー７、転写チャージャー１０、分離チャージャー１１、クリーニング前チャージャー１３には、コロトロン、スコロトロン、固体帯電器（ソリッド・ステート・チャージャー）、帯電ローラを始めとする公知の手段が用いられる。
【００６６】
転写手段には、一般に上記の帯電器が使用できるが、図に示されるように転写チャージャーと分離チャージャーを併用したものが効果的である。
【００６７】
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。
【００６８】
かかる光源等は、図５に示される工程の他に光照射を併用した転写工程、除電工程、クリーニング工程、あるいは前露光などの工程を設けることにより、感光体に光が照射される。
【００６９】
さて、現像ユニット６により感光体１上に現像されたトナーは、転写紙９に転写されるが、全部が転写されるわけではなく、感光体１上に残存するトナーも生ずる。このようなトナーは、ファーブラシ１４およびブレード１５により、感光体より除去される。クリーニングは、クリーニングブラシだけで行なわれることもあり、クリーニングブラシにはファーブラシ、マグファーブラシを始めとする公知のものが用いられる。
【００７０】
電子写真感光体に正（負）帯電を施し、画像露光を行なうと、感光体表面上には正（負）の静電潜像が形成される。
これを負（正）極性のトナー（検電微粒子）で現像すれば、ポジ画像が得られるし、また正（負）極性のトナーで現像すれば、ネガ画像が得られる。
かかる現像手段には、公知の方法が適用されるし、また、除電手段にも公知の方法が用いられる。
【００７１】
図６には、本発明による電子写真プロセスの別の例を示す。感光体２１は前述の方法により作製された分散液を用いて製膜した感光層を有しており、駆動ローラ２２ａ，２２ｂにより駆動され、帯電器２３による帯電、光源２４による画像露光、現像（図示せず）、帯電器２５を用いる転写、光源２６によるクリーニング前露光、ブラシ２７によるクリーニング、光源２８による除電が繰返し行なわれる。図６においては、感光体２１（勿論この場合は支持体が透光性である）に支持体側よりクリーニング前露光の光照射が行なわれる。
【００７２】
以上の図示した電子写真プロセスは、本発明における実施形態を例示するものであって、もちろん他の実施形態も可能である。例えば、図６において支持体側よりクリーニング前露光を行っているが、これは感光層側から行ってもよいし、また、画像露光、除電露光の照射を支持体側から行ってもよい。
【００７３】
一方、光照射工程は、画像露光、クリーニング前露光、除電露光が図示されているが、他に転写前露光、画像露光のプレ露光、およびその他公知の光照射工程を設けて、感光体に光照射を行なうこともできる。
【００７４】
以上に示すような画像形成手段は、複写装置、ファクシミリ、プリンター内に固定して組み込まれていてもよいが、プロセスカートリッジの形でそれら装置内に組み込まれてもよい。プロセスカートリッジとは、感光体を内蔵し、他に帯電手段、露光手段、現像手段、転写手段、クリーニング手段、除電手段を含んだ１つの装置（部品）である。プロセスカートリッジの形状等は多く挙げられるが、一般的な例として、図７に示すものが挙げられる。感光体１６は、導電性支持体上に前述の方法により作製された分散液を用いて製膜した感光層を有してなるものである。
【００７５】
【実施例】
以下、本発明を実施例を挙げて説明するが、本発明はこれら実施例により制約を受けるものではない。なお、部はすべて重量部である。
【００７６】
まず、ブラッグ角２θの最大回折ピークが２７．２°±０．２°にある結晶形（いわゆるＹ型）のチタニルフタロシアニン顔料の具体的な合成例を述べる。
（顔料製造例）
フクロジニトリル５２５部と１−クロロナフタレン４０００部を撹拌混合し、窒素気流下で四塩化チタン１９０部を滴下する。滴下終了後、徐々に２００℃まで昇温し、反応温度を１９０℃〜２１０℃の問に保ちながら５時間撹拌して反応を行った。反応終了後、放冷し１３０℃になったところで熱時ろ過し、ついで１−クロロナフタレンで粉体が青色になるまで洗浄し、つぎにメタノールで数回洗浄し、さらに８０℃の熱水で数回洗浄した後、乾燥し４２２部の粗チタニルフタロシアニン顔料を得た。得られた熱水洗浄処理した粗チタニルフタロシアニン顔料のうち６０部を９６％硫酸１０００部に３〜５℃下で撹拌し、溶解し、ろ過した。得られた硫酸溶液を氷水３５０００部中に撹拌しながら滴下し、析出した結晶をろ過、ついで洗浄液が中性になるまで水洗を繰り返し、チタニルフタロシアニン顔料の水ペーストを得た。この水ぺーストに１，２−ジクロロエタン１５００部を加え、室温下２時間撹拌した後、メタノール２５００部をさらに加え撹拌し、ろ過した。これをメタノール洗浄し、更に乾燥してチタニルフタロシアニン顔料４９部を得た。
【００７７】
顔料製造例で得られたチタニルフタロシアニン顔料についてのＸ線回折スペクトルを以下に示す条件で測定した。
Ｘ線管球 Ｃｕ、 電圧４０ｋＶ、 電流２０ｍＡ、
走査速度１°／分、 走査範囲３°〜４０° 時定数２秒、
【００７８】
顔料製造例で得られたチタニルフタロシアニン顔料のＸ線回折スペクトルを図８に示す。得られたチタニルフタロシアニン顔料はブラッグ角２θの最大ピークが少なくとも２７．２°±０．２°にある結晶形を有していることが分かる。
【００７９】
（実施例１）
顔料製造例で作製した顔料は大きな塊を含んでいたため、市販のミキサーにより粗粉砕を行った。この結果、約２００μｍ以下程度の粉体を得た。
この顔料を用い、図1に示すようなビーズミル分散機を用いて、下記組成の液の分散を行った。循環分散の前に行う全液の分散室の通過操作（仮分散と呼ぶ）を１回行ってから、循環分散を行った。
上記顔料 ３７０部
ブチラール樹脂 ２５０部
２−ブタノン ５０００部
ブチラール樹脂はあらかじめ別の容器で２一ブタノンに溶解しておいたものを使用した。仮分散を１回行った後、循環分散を３０分行った。これを分散液１とする。
【００８０】
（実施例２）
実施例１における仮分散を２回行った以外は、実施例１と全く同様に分散液を作製した。これを分散液２とする。
【００８１】
（比較例１）
実施例１における仮分散を行わなかった以外は、実施例１と全く同様に分散液を作製した。これを分散液３とする。
【００８２】
（比較例２）
実施例１における仮分散を行わず、分散時間を１８０分とした以外は実施例１と全く同様に分散液を作製した。これを分散液４とする。
【００８３】
上記のように作製した分散液を以下のように評価した。粒度分布はＣＡＰＡ７００（堀場製作所社製）にて測定した。また、分散液を乾固し、粉末とした後、Ｘ線回折スペクトルを測定した。結果を表１に示す。
表１より、分散液１〜２は平均粒径も細かく、結晶型の変化のない分散液であることが分かる。
【００８４】
【表１】

【００８５】
（実施例３〜４および比較例３）
電鋳ニッケルベルト上に下記組成の下記組成の下引き層塗工液、電荷発生層塗工液、および電荷輸送層塗工液を、順次塗布・乾燥し、積層感光体を作製した。
〔下引き層塗工液〕
二酸化チタン粉末 １５部
ポリビニルブチラール ６部
２−ブタノン １５０部
〔電荷発生層塗工液〕
実施例３には前記分散液１を用い、実施例４には前記分散液２を用い、比較例３には前記分散液３を用いた。
〔電荷輸送層塗工液〕
ポリカーボネート １０部
下記構造式の電荷輸送物質 ７部
【化１３】

塩化メチレン ８０部
【００８６】
このようにしてなる電子写真感光体を図６に示す電子写真プロセス（ただし、クリーニング前露光は無し）に装着し、画像露光光源を７８０ｍｍの半導体レーザー（ポリゴンミラーによる画像書き込み）とした。連続して１００００枚の印刷を行い、その時の画像評価を行った。結果を表２に示す。
【００８７】
【表２】

分散液３を用いた感光体の電荷発生層は、分散液中に粗大粒子が存在しているため、塗膜欠陥（ポチ、スジなど）を生じた。表２より分散液１〜２を用いた感光体は、繰り返し使用後にも良好な画像を与えていることが分かる。
【００８８】
（実施例５〜６および比較例４）
アルミニウムシリンダー表面を陽極酸化処理した後封孔処理を行った。この上に、下記電荷発生層塗工液、電荷輸送層塗工液を、順次塗布・乾燥して各々０．２μｍ厚の電荷発生層、２０μｍ厚の電荷輸送層を形成し、本発明の電子写真感光体を作製した。
〔電荷発生層塗工液〕
実施例５には前記分散液１を用い、実施例６には前記分散液２を用い、比較例４には前記分散液４を用いた。
〔電荷輸送層塗工液〕
下記構造式の電荷輸送物質 ８部
【化１４】

ポリカーボネート １０部
塩化メチレン ８０部
【００８９】
このようにしてなる電子写真感光体を図７に示す電子写真用プロセスカートリッジに装着した後、画像形成装置に搭載した。画像露光光源を７８０ｍｍの半導体レーザー（ポリゴンミラーによる画像書き込み）として、現像直前の感光体の表面電位が測定できるように表面電位計のプローブを挿入した。連続して５０００枚の印刷を行い、その時の画像露光部と画像非露光部の表面電位を初期と５０００枚後に測定した結果を表３に示す。
【００９０】
【表３】

表３より、分散液１〜２を用いた感光体は、繰り返し使用後にも安定した表面電位を維持していることが分かる。
【００９１】
実施例７
実施例１における支持体を電鋳ニッケル・ベルトからアルミシリンダーに変えた以外は実施例１と全く同様に感光体を作製した。
【００９２】
実施例８
実施例１の電荷輸送層塗工液を以下の組成に変えた以外は、実施例１と全く同様に感光体を作製した。
〔電荷輸送層塗工液〕
下記構造式の高分子電荷輸送物質 １０部
【化１５】

塩化メチレン １００部
【００９３】
実施例９
実施例１の電荷輸送層塗工液を以下の組成に変えた以外は、実施例１と全く同様に感光体を作製した。
〔電荷輸送層塗工液〕
下記構造式の高分子電荷輸送物質 １０部
【化１６】

塩化メチレン １００部
【００９４】
上記の実施例７〜９の各電子写真感光体を図５に示す電子写真プロセスに装着し（ただし、画像露光光源を７８０ｎｍに発光を持つＬＤとした）、連続して一万枚の印刷を行い、その時の画像を初期と一万枚後に評価した。また、電荷輸送層の膜厚の変化（減少量）を測定した。結果を表４に示す。
【００９５】
【表４】

【００９６】
【発明の効果】
本発明によれば、分散液作製にあたり非常に効率的に、かつ結晶型を変えることない分散液の作製する方法が提供され、これを用いることにより、特定の結晶型を維持したまま、粒径の細かい分散液が提供される。この分散液は、電子写真感光体用分散液として非常に有用であり、特定の感光体特性を与え、かつ塗膜欠陥の少ない感光体を作製することが可能である。これにより、特定の特性（高感度・繰り返し使用によっても安定な表面電位）を維持しつつ、耐摩耗性の高い感光体が提供される。更に、高感度を失うことなく繰り返し使用によっても帯電性の低下と残留電位の上昇を生じない安定な電子写真装置および電子写真装置用プロセスカートリッジが提供される。
【図面の簡単な説明】
【図１】本発明における感光層を形成するための分散液を得るのに好適な装置の概略図。
【図２】本発明で用いられる電子写真感光体の模式断面図。
【図３】本発明で用いられる別の電子写真感光体の模式断面図。
【図４】本発明で用いられる更に別の電子写真感光体の模式断面図。
【図５】本発明の電子写真プロセスおよび電子写真装置を説明するための概略図。
【図６】本発明の電子写真プロセスおよび電子写真装置を説明するための概略図。
【図７】本発明の代表的な電子写真装置を説明するための概略図。
【図８】本発明の合成例により得られるチタニルフタロシアン顔料のＸ線回折スペクトル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating liquid for a photosensitive layer, an electrophotographic photosensitive member using the same, an electrophotographic method using the electrophotographic photosensitive member, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus. The present invention relates to an electrophotographic photosensitive member excellent in stability of a charging potential and a residual potential of the photosensitive member, an electrophotographic method using the same, an electrophotographic apparatus, and a process cartridge for the electrophotographic apparatus.
[0002]
[Prior art]
Conventional electrophotographic photoconductors, particularly electrophotographic organic photoconductors using organic photoconductors, are less costly and have little toxicity compared to conventional inorganic photoconductors prepared by vacuum deposition of selenium films. There are many advantages such as the ease of film formation, and it is becoming the mainstream of current electrophotographic photoreceptors.
[0003]
Organic photoreceptors are so-called single-layer photoreceptors or conductive supports in which a coating solution for a photosensitive layer containing a charge generation material, a charge transport material, a binder resin, and the like is formed on a conductive support by dip coating or the like. There is a laminated photoreceptor in which a charge generation layer is formed using a coating liquid containing a charge generation material and then a charge transport layer is formed using a coating liquid containing a charge transport material. The laminated photoreceptor may be coated with an undercoat layer, a protective layer, or the like for the purpose of improving image quality or durability.
[0004]
However, it cannot be said that there is no problem in electrostatic repetitive characteristics, whether it is a single layer type electrophotographic photosensitive member or a laminated type electrophotographic photosensitive member. There has been a problem that the charging potential is lowered or the surface potential is lowered in the time from charging to development, that is, so-called dark decay is increased.
[0005]
By the way, an organic pigment which is a photoconductive substance for forming a photosensitive layer has been used as a filler for paints for a relatively long time. In particular, the richness of the color is an advantage not found in inorganic pigments. In recent years, as an application example of organic pigments, various materials have been produced since they have been spotlighted as materials for organic photoelectric conversion devices.
[0006]
In forming such a film containing an organic pigment, most of the wet film forming methods that can easily increase the area are occupied. It is no exaggeration to say that the quality of a coating film formed by a wet film formation method is almost dependent on the quality of a dispersion containing a pigment. The quality of the dispersion is determined by the dispersibility of the pigment. Therefore, a good dispersion is one in which the pigment is sufficiently dispersed in the vehicle and the dispersion state continues for a long time.
[0007]
In order to prepare such a dispersion, various dispersers and dispersion systems have been proposed so far, and methods for increasing the dispersion efficiency have been devised. In order to reduce the particle size of the pigment in the dispersion, generally, a dispersion medium having a small size is used. However, if the pigment is difficult to disperse, the dispersion power is insufficient. The only way to improve this is to increase the media size or use pigments that are easily dispersed. Since the former has a limit on the final particle size, it is efficient to develop the latter method. However, there are few approaches from the pigment side regarding dispersion.
[0008]
On the other hand, the development of an information processing system using an electrophotographic system is remarkable. In particular, an optical printer that converts information into a digital signal and records information by light has a remarkable improvement in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, it is expected that its demand will increase further in the future.
[0009]
As a light source for an optical printer, a small-sized, inexpensive and highly reliable semiconductor laser (LD) or light emitting diode (LED) is currently used. The light emission wavelength of the LED that is often used at present is 660 nm, and the light emission wavelength region of the LD is in the near infrared light region. Therefore, development of an electrophotographic photoreceptor having high sensitivity from the visible light region to the near infrared light region is desired.
[0010]
The photosensitive wavelength region of the electrophotographic photosensitive member is almost determined by the photosensitive wavelength region of the charge generating material used in the photosensitive member. Therefore, many charge generating materials such as various azo pigments, polycyclic quinone pigments, trigonal selenium and various phthalocyanine pigments have been developed. Among them, titanyl phthalocyanine (abbreviated as TiOPc) exhibits high sensitivity to light having a long wavelength of 600 to 800 nm, and therefore, a photoconductor material for an electrophotographic printer or digital copying machine whose light source is LED or LD. As extremely important and useful.
[0011]
In addition, the electrophotographic photosensitive member used repeatedly in the Carlson process and similar processes has excellent electrostatic characteristics such as sensitivity, receptive potential, potential retention, potential stability, residual potential, and spectral characteristics. Is required. In particular, for high-sensitivity photoconductors, it has been empirically known that many photoconductors have a decrease in chargeability and an increase in residual potential due to repeated use. It is not an exception. Therefore, stability due to repeated use of a photoreceptor using titanyl phthalocyanine has not been sufficient yet, and the completion of the technique has been eagerly desired. There has also been a demand for production of a dispersion capable of stably producing a photoreceptor having these characteristics for a long period of time.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a stable electrophotographic photosensitive member that does not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity. Another object of the present invention is to provide an electrophotographic photosensitive member having improved wear resistance while maintaining the above characteristics. Another object of the present invention is to provide a stable electrophotographic method which does not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity. Still another object of the present invention is to provide a stable electrophotographic apparatus and a process cartridge for an electrophotographic apparatus that do not cause deterioration in chargeability and increase in residual potential even after repeated use without losing high sensitivity.
[0013]
[Means for Solving the Problems]
The inventor considered the electrophotographic photosensitive member as follows. That is, as described above, the organic pigment plays an important role as a photocarrier generating material for an electrophotographic photoreceptor. The organic pigment is generally present in the form of fine particles in the electrophotographic photoreceptor. This is because the image writing light in the electrophotographic process is uniformly absorbed at a certain rate. For this reason, if the particles are too large or the particle size distribution is sparse, the resulting electrophotographic photoreceptor not only has a clean coating film on the photosensitive layer (charge generation layer) containing the organic pigment, but also abnormal in the electrophotographic process. An image may be generated.
In view of the above points, it is preferable that the organic pigment as the charge generation material has a narrow particle size distribution and a particle size as small as possible in the dispersion for forming the photosensitive layer (charge generation layer). That is, it is no exaggeration to say that the production of a dispersion having high dispersion stability is the success or failure of an electrophotographic photoreceptor.
[0014]
An electrophotographic photoreceptor containing an organic pigment is generally formed by a wet method. In particular, the dip coating method suitable for mass production is the majority of the method for producing a drum-shaped photoreceptor. The dip coating method is most suitable for mass-product manufacturing because the apparatus and method are simple. However, even when a small number of coatings are applied, the minimum amount of coating solution is required. This minimum required amount is extremely large as compared with other coating methods such as spraying method and nozzle coating method.
[0015]
Various methods for dispersing organic pigments have been proposed, but some limitations arise when producing a large amount of dispersion. That is, in a ball mill, a vibration mill, etc., the capacity of the pot determines the amount that can be produced. From such a viewpoint, as a dispersion system capable of producing a large amount of dispersion liquid in one batch, a dispersion system having a portion having dispersion ability, that is, a dispersion chamber portion (dispersion chamber) in the circulation system has been proposed.
[0016]
Such a system is generally designed to have a small capacity of the dispersion chamber with respect to a large-capacity stock tank. This is for the purpose of compacting the system, saving energy, and reducing the number of distributed media used in the distributed room. As a flow of the dispersion method, when the liquid sent from the stock tank to the dispersion chamber and the liquid dispersed in the dispersion chamber returns to the stock tank again, the dispersed liquid is completely mixed with the liquid before dispersion. However, if the capacity of the dispersion chamber is too small relative to the capacity of the stock tank, the liquid in the stock tank is almost undispersed (liquid that has never passed through the dispersion chamber). For this reason, it takes much time to disperse and it is not efficient. Furthermore, since one part of liquid passes through the dispersion chamber many times, it may become overdispersed or even change the crystal form in some cases. When a photoreceptor is prepared using the dispersion thus prepared, the nonuniformity of the coating film due to the nonuniformity of the particle size distribution, or the change in electrostatic characteristics due to the change or alteration of crystal type (desired electrostatic property). Such as inability to obtain characteristics).
[0017]
As described above, the present inventor thinks that the circulation and dispersion system itself is very preferable, but it is fatal that the liquid that has passed through the dispersion chamber once is mixed with a large amount of undispersed liquid and buried. I found it to be a drawback. In order to improve this point, the dispersion efficiency is dramatically improved by circulating the dispersion after all the liquid to be dispersed passes through the dispersion chamber, and the crystal type has a stable and uniform particle size distribution. We have found that a dispersion can be prepared. By using this dispersion, an electrophotographic photosensitive member having good film formability and stable electrostatic characteristics is formed.
In addition, the present inventor has found that a photoreceptor using a dispersion prepared by using the above-described technique is deteriorated in chargeability / photosensitivity (residual potential) in repeated use, which has been a problem in the past, when used in an electrophotographic process. It was found that a stable surface potential can be provided without causing an increase in As a result, it has been found that the occurrence of abnormal images such as background contamination or image density reduction can be suppressed, and the present invention has been completed.
[0018]
According to the present invention, firstly, a dispersion mainly containing an organic pigment, a binder resin, and a solvent, which has passed through a dispersion chamber (dispersion chamber) provided in one circulation system, and its dispersion The dispersion is the same component as that of the liquid and is separated from the dispersion before passing through the dispersion chamber, and after all the dispersion has passed through the dispersion chamber at least once, it is prepared by continuous circulation dispersion. A characteristic photosensitive layer coating solution is provided.
[0019]
Second, there is provided the first photosensitive layer coating solution, wherein the organic pigment is a phthalocyanine pigment.
[0020]
Third, the second photosensitive layer coating solution is provided, wherein the phthalocyanine pigment is titanyl phthalocyanine.
[0021]
Fourth, the characteristic X-ray (wavelength of the organic pigment is at least CuKa) 1.541 The photosensitive layer coating liquid according to any one of the first to third aspects is provided, which is titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ° ± 0.2 ° with respect to (ii). The
[0022]
Fifth, there is provided an electrophotographic photosensitive member characterized by having a photosensitive layer formed by applying the photosensitive layer coating liquid according to any one of the above first to fourth on a conductive support. The
[0023]
Sixth, the electrophotographic photosensitive member according to the fifth aspect is provided, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.
[0024]
Seventh, there is provided the electrophotographic photosensitive member according to the sixth aspect, wherein the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.
[0025]
Eighth, in the electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeatedly performed on the electrophotographic photosensitive member, the electrophotographic photosensitive member is any one of the above first to fourth elements on a conductive support. An electrophotographic method comprising a photosensitive layer formed by applying the photosensitive layer coating solution described in 1. above is provided.
[0026]
Ninth, an electrophotographic apparatus comprising at least a charging means, an image exposing means, a developing means, a transferring means, a cleaning means, a charge eliminating means, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is a conductive support. An electrophotographic apparatus comprising a photosensitive layer formed by applying the photosensitive layer coating liquid according to any one of the first to fourth above is provided.
[0027]
Tenthly, a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is provided on a conductive support for the photosensitive layer according to any one of the first to fourth aspects. There is provided a process cartridge for an electrophotographic apparatus having a photosensitive layer formed by applying a coating liquid.
[0028]
[Form of the present invention]
Hereinafter, the present invention will be described in detail.
As the organic pigment used in the electrophotographic photoreceptor produced in the present invention, any known organic pigment can be applied. For example, phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinones. Pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric acid dyes, naphthalocyanine pigments, azulenium salt dyes, and the like.
[0029]
Phthalocyanine pigments having a large number of crystal types are very effective. Among them, titanyl phthalocyanine is a pigment, although its characteristics greatly change depending on the crystal types. In particular, the characteristic X-ray (wavelength of CuKα) 1.541 Titanyl phthalocyanine with a Bragg angle 2θ maximum diffraction peak of 27.2 ° ± 0.2 ° with respect to Å) has an extremely high photocarrier generation ability, but its crystal form is unstable and easy to other crystal forms Will be converted to. However, in the present invention, a dispersion can be produced while stably maintaining the crystal form, and an electrophotographic photosensitive member can be obtained while maintaining the original photocarrier generation ability of the pigment.
[0030]
FIG. 1 is a view showing an example of an apparatus suitable for producing a coating solution for forming a photosensitive layer of the electrophotographic photosensitive member of the present invention. In FIG. 1, reference numeral 51 denotes a dispersion chamber (dispersion chamber portion) in which a rotor rotating at high speed by a motor 52 and beads for dispersion are contained.
As the beads, zirconia beads or glass beads having a diameter of about 0.3 mm to 1 mm are used. 53A and 53B are stock tanks in which the liquid dispersed inside is stored.
In the example of FIG. 1, there are two stock tanks, but three or more may be used. In addition, although the stock tanks 53A and 53B have the same shape, it is not always necessary to have the same shape. 54A and 54B are agitators for agitating the liquid in the stock tank, and 55 is a pump for sending the liquid in the stock tank to the dispersion chamber. Reference numeral 58 denotes a three-way valve that enables switching between the liquid in the stock tank 3 </ b> A and the liquid in the stock tank 3 </ b> B as the liquid sent to the dispersion chamber 1.
[0031]
FIG. 1 shows an example with two stock tanks. However, when the number of stock tanks increases, the valve 58 in FIG. 1 is not a three-way valve but a four-way or more switching valve. The valve 59 is also a three-way valve, and enables switching of whether the liquid discharged from the dispersion chamber is put into the stock tank 53A or 53B. As with the valve 58, the number of switching of the valve 59 increases according to the number of stock tanks, and switching is possible.
[0032]
Using such a device, the liquid before dispersion is first put in one stock tank, sent to the dispersion chamber by a pump, and the dispersed liquid is adjusted by valves 58 and 59 so as to be stored only in the other stock tank. To do. Thereafter, the valves 58 and 59 are adjusted so that the dispersion liquid does not enter the tank on one side, and circulation dispersion is started.
In order to pass the dispersion chamber before circulation twice or more, the above operation (one-sided passage of the dispersion liquid between the stock tanks) may be repeated twice or more. As the number of operations increases, the particle size distribution becomes more uniform. However, since it takes time and labor to disperse, the number of operations may be adjusted depending on the material.
[0033]
FIG. 2 is a cross-sectional view showing the electrophotographic photosensitive member used in the present invention, and a single-layer photosensitive layer 33 mainly composed of a charge generating material and a charge transporting material is provided on a conductive support 31. . FIG. 3 and FIG. 4 are cross-sectional views showing another configuration example of the electrophotographic photosensitive member used in the present invention, and a charge generation layer 35 mainly composed of a charge generation material and a charge mainly composed of a charge transport material. The transport layer 37 has a laminated structure.
[0034]
The conductive support 31 has a volume resistance of 10 ¹⁰ Films having conductivity of Ω · cm or less, for example, metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxide such as tin oxide, indium oxide, etc. are deposited or sputtered. Or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. and surface after cutting, superfinishing, polishing, etc. after extruding and drawing them out Treated tubes and the like can be used. Further, an endless nickel belt or an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can also be used as the conductive support 31.
[0035]
In addition, the conductive support 31 of the present invention can be used in which conductive powder is dispersed in a suitable binder resin and coated on the support. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done.
The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic resins such as melamine resin, urethane resin, phenol resin, and alkyd resin, thermosetting resin, and photocurable resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
[0036]
Furthermore, a conductive layer is provided on a suitable cylindrical substrate by a heat-shrinkable tube containing the conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon. Can be used favorably as the conductive support 31 of the present invention.
[0037]
Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a laminate, but for convenience of explanation, the case where it is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.
[0038]
The charge generation layer 35 is a layer mainly composed of an organic pigment. This is a layer formed by forming a film of the dispersion prepared by the method described above.
As the binder resin used for the charge generation layer 35 as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N -Vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. can give. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material.
[0039]
Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The thickness of the charge generation layer 35 is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.
[0040]
The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
[0041]
Charge transport materials include hole transport materials and electron transport materials. Examples of the charge transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone and 2,4. , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
[0042]
Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-galvazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazine derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.
[0043]
Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.
[0044]
The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm. As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.
[0045]
In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. A known material can be used as the polymer charge transporting material, but a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (1) to (10) are favorably used, and these are exemplified below and specific examples are shown.
[0046]
[Chemical 1]

Where R ₁ , R ₂ , R _Three Each independently represents a substituted or unsubstituted alkyl group or a halogen atom, R _Four Is a hydrogen atom or a substituted or unsubstituted alkyl group, R _Five , R ₆ Is a substituted or unsubstituted aryl group, o, p and q are each independently an integer of 0 to 4, k and j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, n Represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.
[Chemical formula 2]

Where R ₁₀₁ , R ₁₀₂ Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -SO. ₂ -, -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or
[Chemical 3]

In the formula, a is an integer of 1 to 20, b is an integer of 1 to 2000, R ₁₀₃ , R ₁₀₄ Represents a substituted or unsubstituted alkyl group or aryl group. Where R ₁₀₁ And R ₁₀₂ , R ₁₀₃ And R ₁₀₄ May be the same or different.
[0047]
[Formula 4]

Where R ₇ , R ₈ Is a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ , Ar _Three Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0048]
[Chemical formula 5]

Where R ₉ , R _Ten Is a substituted or unsubstituted aryl group, Ar _Four , Ar _Five , Ar ₆ Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0049]
[Chemical 6]

Where R ₁₁ , R ₁₂ Is a substituted or unsubstituted aryl group, Ar ₇ , Ar ₈ , Ar ₉ Are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j, and n are the same as in the case of equation (1).
[0050]
[Chemical 7]

Where R ₁₃ , R ₁₄ Is a substituted or unsubstituted aryl group, Ar _Ten , Ar ₁₁ , Ar ₁₂ Are the same or different arylene groups, X ₁ , X ₂ Represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j, and n are the same as in the case of equation (1).
[0051]
[Chemical 8]

Where R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ Is a substituted or unsubstituted aryl group, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , Ar ₁₆ Are the same or different arylene groups, Y ₁ , Y ₂ , Y _Three Represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, which may be the same or different. . X, k, j, and n are the same as in the case of equation (1).
[0052]
[Chemical 9]

Where R ₁₉ , R ₂₀ Represents a hydrogen atom, a substituted or unsubstituted aryl group, and R ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ , Ar ₁₉ Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0053]
[Chemical Formula 10]

Where R _{twenty one} Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar _{twenty one} , Ar _{twenty two} , Ar _{twenty three} Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0054]
Embedded image

Where R _{twenty two} , R _{twenty three} , R _{twenty four} , R _{twenty five} Is a substituted or unsubstituted aryl group, Ar _{twenty four} , Ar _{twenty five} , Ar ₂₆ , Ar ₂₇ , Ar ₂₈ Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0055]
Embedded image

Where R ₂₆ , R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ , Ar ₃₁ Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0056]
In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight with respect to the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 1 weight with respect to the binder resin. % Is appropriate.
[0057]
Next, the case where the photosensitive layer has a single layer structure 33 will be described. The single-layer photosensitive layer can be formed by dispersing a charge generating substance, a charge transporting substance, and a binder resin in an appropriate solvent by the above-described method, and applying and drying it. Further, the photosensitive layer may be a function separation type to which the above-described charge transport material is added, and can be used satisfactorily. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
[0058]
As the binder resin, the binder resin previously mentioned in the charge transport layer 37 may be used as it is, or the binder resin mentioned in the charge generation layer 35 may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. The amount of the charge generation material is preferably 5 to 40 parts by weight, and the amount of the charge transport material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight with respect to 100 parts by weight of the binder resin. A single-layer photosensitive layer is formed by dip coating or spraying with a coating solution dispersed with a disperser using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane together with a charge transport material, if necessary, with a charge generating material and a binder resin. It can be formed by coating with a coat or bead coat. The thickness of the single photosensitive layer is suitably about 5 to 100 μm.
[0059]
In the electrophotographic photosensitive member of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.
[0060]
These undercoat layers can be formed using an appropriate solvent and coating method as in the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention includes A1. ₂ O _Three Anodic oxidation, organic materials such as polyparaxylylene (parylene), and SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.
[0061]
In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, poly Examples of the resin include vinylidene chloride and epoxy resin. In addition to the protective layer, fluorine resins such as polytetrafluoroethylene, silicone resins, and those resins dispersed with inorganic materials such as titanium oxide, tin oxide, potassium titanate, etc. for the purpose of improving wear resistance, etc. Can be added. As a method for forming the protective layer, a normal coating method is adopted. The thickness of the protective layer is suitably about 0.1 to 10 μm. In addition to the above, a known material such as a-C or a-SiC formed by a vacuum thin film forming method can be used as the protective layer.
[0062]
In the present invention, an intermediate layer may be provided between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.
[0063]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings.
[0064]
FIG. 5 is a schematic diagram for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention.
[0065]
In FIG. 5, the photoreceptor 1 is formed by providing a photosensitive layer formed on a conductive support using the dispersion prepared by the above-described method. The photosensitive member 1 has a drum shape, but may be a sheet shape or an endless belt shape. As the charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. It is done.
[0066]
As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.
[0067]
The light source such as the image exposure unit 5 and the charge removal lamp 2 emits light 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. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
[0068]
Such a light source or the like irradiates the photosensitive member with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG.
[0069]
The toner developed on the photosensitive member 1 by the developing unit 6 is transferred to the transfer paper 9, but not all is transferred, and some toner remains on the photosensitive member 1. Such toner is removed from the photoreceptor by the fur brush 14 and the blade 15. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.
[0070]
When the electrophotographic photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member.
A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.
A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.
[0071]
FIG. 6 shows another example of the electrophotographic process according to the present invention. The photosensitive member 21 has a photosensitive layer formed by using the dispersion prepared by the above-described method, and is driven by driving rollers 22a and 22b to be charged by a charger 23, image exposure by a light source 24, and development (development). (Not shown), transfer using the charger 25, exposure before cleaning with the light source 26, cleaning with the brush 27, and static elimination with the light source 28 are repeated. In FIG. 6, the photoconductor 21 (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.
[0072]
The above illustrated electrophotographic process is illustrative of an embodiment of the present invention, and of course other embodiments are possible. For example, in FIG. 6, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or the image exposure and the discharge exposure may be performed from the support side.
[0073]
On the other hand, in the light irradiation process, image exposure, pre-cleaning exposure, and static elimination exposure are illustrated, but other pre-exposure exposure, pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.
[0074]
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. The photoreceptor 16 has a photosensitive layer formed by using the dispersion prepared by the above-described method on a conductive support.
[0075]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not restrict | limited by these Examples. All parts are parts by weight.
[0076]
First, a specific synthesis example of a crystal form (so-called Y type) titanyl phthalocyanine pigment having a maximum diffraction peak with a Bragg angle 2θ of 27.2 ° ± 0.2 ° will be described.
(Example of pigment production)
525 parts of fuclodinitrile and 4000 parts of 1-chloronaphthalene are mixed with stirring, and 190 parts of titanium tetrachloride are added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 200 ° C., and the reaction was carried out by stirring for 5 hours while keeping the reaction temperature between 190 ° C. and 210 ° C. After completion of the reaction, the mixture was allowed to cool and filtered when heated to 130 ° C., then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further with hot water at 80 ° C. After washing several times, it was dried to obtain 422 parts of crude titanyl phthalocyanine pigment. 60 parts of the obtained crude titanyl phthalocyanine pigment washed with hot water was stirred and dissolved in 1000 parts of 96% sulfuric acid at 3 to 5 ° C., and filtered. The obtained sulfuric acid solution was added dropwise to 35000 parts of ice water with stirring, the precipitated crystals were filtered, and then washed with water until the washing solution became neutral to obtain an aqueous paste of titanyl phthalocyanine pigment. To this water paste, 1,500 parts of 1,2-dichloroethane was added and stirred at room temperature for 2 hours. Then, 2500 parts of methanol was further added and stirred, followed by filtration. This was washed with methanol and further dried to obtain 49 parts of a titanyl phthalocyanine pigment.
[0077]
The X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained in the pigment production example was measured under the following conditions.
X-ray tube Cu, voltage 40 kV, current 20 mA,
Scanning speed 1 ° / min, scanning range 3 ° -40 °, time constant 2 seconds,
[0078]
An X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained in the pigment production example is shown in FIG. It can be seen that the resulting titanyl phthalocyanine pigment has a crystal form with a maximum peak at a Bragg angle 2θ of at least 27.2 ° ± 0.2 °.
[0079]
(Example 1)
Since the pigment produced in the pigment production example contained large lumps, coarse pulverization was performed using a commercially available mixer. As a result, a powder of about 200 μm or less was obtained.
Using this pigment, a liquid having the following composition was dispersed using a bead mill disperser as shown in FIG. After passing through the dispersion chamber of all liquids (referred to as temporary dispersion) performed once before circulation dispersion, circulation dispersion was performed.
370 parts of the above pigment
250 parts of butyral resin
2-butanone 5000 parts
The butyral resin used in advance was dissolved in 2-butanone in a separate container. After performing temporary dispersion once, circulation dispersion was performed for 30 minutes. This is designated as Dispersion Liquid 1.
[0080]
(Example 2)
A dispersion was prepared in exactly the same manner as in Example 1, except that the temporary dispersion in Example 1 was performed twice. This is Dispersion Liquid 2.
[0081]
(Comparative Example 1)
A dispersion was prepared in exactly the same manner as in Example 1 except that the temporary dispersion in Example 1 was not performed. This is Dispersion Liquid 3.
[0082]
(Comparative Example 2)
A dispersion was prepared in exactly the same manner as in Example 1 except that the temporary dispersion in Example 1 was not performed and the dispersion time was 180 minutes. This is Dispersion Liquid 4.
[0083]
The dispersions prepared as described above were evaluated as follows. The particle size distribution was measured with CAPA700 (Horiba Seisakusho). The dispersion was dried and powdered, and then the X-ray diffraction spectrum was measured. The results are shown in Table 1.
From Table 1, it can be seen that the dispersions 1 and 2 are fine dispersions having a fine average particle diameter and no change in crystal form.
[0084]
[Table 1]

[0085]
(Examples 3 to 4 and Comparative Example 3)
On the electroformed nickel belt, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried to prepare a laminated photoreceptor.
[Undercoat layer coating solution]
Titanium dioxide powder 15 parts
Polyvinyl butyral 6 parts
2-butanone 150 parts
[Charge generation layer coating solution]
The dispersion 1 was used in Example 3, the dispersion 2 was used in Example 4, and the dispersion 3 was used in Comparative Example 3.
[Charge transport layer coating solution]
10 parts of polycarbonate
7 parts of charge transport material with the following structural formula
Embedded image

80 parts of methylene chloride
[0086]
The electrophotographic photosensitive member thus formed was mounted on the electrophotographic process shown in FIG. 6 (without exposure before cleaning), and an image exposure light source was a 780 mm semiconductor laser (image writing by a polygon mirror). 10,000 sheets were printed continuously, and image evaluation at that time was performed. The results are shown in Table 2.
[0087]
[Table 2]

The charge generation layer of the photoreceptor using the dispersion liquid 3 had coating film defects (such as spots and streaks) because coarse particles were present in the dispersion liquid. It can be seen from Table 2 that the photoreceptors using the dispersions 1 and 2 give good images even after repeated use.
[0088]
(Examples 5 to 6 and Comparative Example 4)
The aluminum cylinder surface was anodized and then sealed. On top of this, the following charge generation layer coating solution and charge transport layer coating solution are sequentially applied and dried to form a 0.2 μm thick charge generation layer and a 20 μm thick charge transport layer, respectively. A photographic photoreceptor was prepared.
[Charge generation layer coating solution]
The dispersion 1 was used in Example 5, the dispersion 2 was used in Example 6, and the dispersion 4 was used in Comparative Example 4.
[Charge transport layer coating solution]
8 parts of charge transport material of the following structural formula
Embedded image

10 parts of polycarbonate
80 parts of methylene chloride
[0089]
The electrophotographic photosensitive member thus formed was mounted on the electrophotographic process cartridge shown in FIG. 7 and then mounted on the image forming apparatus. As the image exposure light source, a 780 mm semiconductor laser (image writing by a polygon mirror) was used, and a surface potential meter probe was inserted so that the surface potential of the photoconductor immediately before development could be measured. Table 3 shows the results obtained by printing 5000 sheets continuously and measuring the surface potential of the image exposed part and the image non-exposed part at the initial stage and after 5000 sheets.
[0090]
[Table 3]

From Table 3, it can be seen that the photoreceptor using the dispersions 1 and 2 maintains a stable surface potential even after repeated use.
[0091]
Example 7
A photoconductor was prepared in exactly the same manner as in Example 1 except that the support in Example 1 was changed from an electroformed nickel belt to an aluminum cylinder.
[0092]
Example 8
A photoconductor was prepared in exactly the same manner as in Example 1, except that the charge transport layer coating solution of Example 1 was changed to the following composition.
[Charge transport layer coating solution]
10 parts of polymer charge transport material of the following structural formula
Embedded image

100 parts methylene chloride
[0093]
Example 9
A photoconductor was prepared in exactly the same manner as in Example 1, except that the charge transport layer coating solution of Example 1 was changed to the following composition.
[Charge transport layer coating solution]
10 parts of polymer charge transport material of the following structural formula
Embedded image

100 parts methylene chloride
[0094]
Each of the electrophotographic photosensitive members of Examples 7 to 9 described above was mounted on the electrophotographic process shown in FIG. 5 (however, the image exposure light source was an LD having a light emission at 780 nm), and 10,000 sheets were printed continuously. The images at that time were evaluated after the initial and 10,000 sheets. Further, the change (decrease amount) in the thickness of the charge transport layer was measured. The results are shown in Table 4.
[0095]
[Table 4]

[0096]
【The invention's effect】
According to the present invention, there is provided a method for preparing a dispersion that is very efficient and does not change the crystal form in the preparation of the dispersion. By using this, the particle size can be maintained while maintaining a specific crystal form. Of fine dispersion. This dispersion is very useful as a dispersion for an electrophotographic photoreceptor, and can provide a photoreceptor having specific photoreceptor characteristics and few coating film defects. This provides a photoconductor having high wear resistance while maintaining specific characteristics (high sensitivity and stable surface potential even after repeated use). Furthermore, there are provided a stable electrophotographic apparatus and a process cartridge for an electrophotographic apparatus that do not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity.
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus suitable for obtaining a dispersion for forming a photosensitive layer in the present invention.
FIG. 2 is a schematic cross-sectional view of an electrophotographic photosensitive member used in the present invention.
FIG. 3 is a schematic cross-sectional view of another electrophotographic photosensitive member used in the present invention.
FIG. 4 is a schematic cross-sectional view of still another electrophotographic photosensitive member used in the present invention.
FIG. 5 is a schematic diagram for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.
FIG. 6 is a schematic view for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.
FIG. 7 is a schematic view for explaining a typical electrophotographic apparatus of the present invention.
FIG. 8 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment obtained by the synthesis example of the present invention.

Claims (10)

  A dispersion mainly composed of an organic pigment, a binder resin, and a solvent that has passed through a dispersion chamber provided in one circulation system, and the same component as the dispersion before passing through the dispersion chamber A coating solution for a photosensitive layer, which is prepared by separating from a dispersion liquid and continuously circulating and dispersing after all the dispersion liquid has passed through the dispersion chamber at least once.   2. The photosensitive layer coating solution according to claim 1, wherein the organic pigment is a phthalocyanine pigment.   3. A coating solution for a photosensitive layer according to claim 2, wherein the phthalocyanine pigment is titanyl phthalocyanine. The organic pigment is titanyl phthalocyanine having a Bragg angle 2θ maximum diffraction peak of 27.2 ° ± 0.2 ° with respect to at least CuKα characteristic X-ray (wavelength 1.541 Å). The coating liquid for photosensitive layers in any one of.   An electrophotographic photosensitive member comprising a photosensitive layer formed by coating the photosensitive layer coating liquid according to claim 1 on a conductive support.   6. The electrophotographic photosensitive member according to claim 5, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.   7. The electrophotographic photoreceptor according to claim 6, wherein the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.   5. The electrophotographic photosensitive member according to claim 1, wherein at least charging, image exposure, development, transfer, cleaning, and static elimination are repeated on the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is provided on the conductive support. An electrophotographic method comprising a photosensitive layer formed by applying a layer coating solution.   An electrophotographic apparatus comprising at least a charging means, an image exposing means, a developing means, a transferring means, a cleaning means, a charge eliminating means, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is provided on a conductive support. 5. An electrophotographic apparatus comprising a photosensitive layer formed by applying the photosensitive layer coating solution according to any one of 1 to 4.   A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is coated with the photosensitive layer coating liquid according to claim 1 on a conductive support. A process cartridge for an electrophotographic apparatus, comprising a photosensitive layer formed by processing.

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