JP4180177B2 - Dispersion preparation method, dispersion, 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。
【００４９】
【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。
【００５０】
【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。
【００５１】
【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。
【００５２】
【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。
【００５３】
【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。
【００５４】
【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。
【００５５】
【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。
【００５６】
【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。
【００５７】
【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。
【００５８】
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。
【００５９】
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、上気した分散液に、電荷輸送物質および結着樹脂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。
【００６０】
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。
【００６１】
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。
【００６２】
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製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。
【００６３】
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製法にて形成した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。
【００６４】
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。
【００６５】
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。
【００６６】
図４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、以下に示すような変形例も本発明の範疇に属するものである。
【００６７】
図４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。
【００６８】
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。
【００６９】
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。
【００７０】
かかる光源等は、図４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。
【００７１】
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。
【００７２】
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。
【００７３】
図５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５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。
【００７４】
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５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。
【００７５】
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。
【００７６】
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６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。感光体１６は、導電性支持体上に特定のＸ線回折スペクトルを与えるＴｉＯＰｃ感光層を有してなるものである。
【００７７】
【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。
【００７８】
実施例１
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５２．５部と１−クロロナフタレン４００部を撹拌混合し、窒素気流下で四塩化チタン１９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４２．２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を９６％硫酸１００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３５００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ウェットケーキを得た。このウェットケーキ６部およびブチラール樹脂４部を溶解した２−ブタノン３２０部を直径２ｍｍのジルコニアボールを入れたガラスポットに投入し、ボールミルにより２時間分散し、分散液を得た（これを分散液１とする）。
【００７９】
得られた水洗後のウェットケーキおよび分散液の部を乾固し、その粉末についての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、
【００８０】
ウェットケーキの乾燥品のＸ線回折スペクトルを図７に示す。得られたウェットケーキ中の顔料は不定形を有していることが分かる。
また、実施例１より得られた分散液中の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の最大回折ピークが２７．２°±０．２°にある結晶形を有していることが分かる。
【００８１】
実施例２
実施例１で得られた硫酸ペースティング処理後のウェットケーキ６部およびブチラール樹脂４部を溶解したテトラヒドロフラン３２０部を直径０．２ｍｍのジルコニアビーズの入ったビーズミル分散機で分散した以外は実施例１と全く同様にして分散液を作製した（これを分散液２とする）。
【００８２】
参考例１
実施例１で得られた硫酸ペースティング処理後のウェットケーキ６部および２−ブタノン３２０部（ブチラール樹脂は加えない）を実施例１と同じ条件でボールミルを行い、分散液に実施例１で用いたブチラール樹脂４部を後から溶解した以外は実施例１と同様にして分散液を作製した（これを分散液３とする）。
【００８３】
比較例１
実施例１で得られた硫酸ペースティング処理後のウェットケーキ６部を２−ブタノン３２０部（ブチラール樹脂は加えない）で結晶変換を行い、濾過した後、８０℃で１日真空乾燥を行い、顔料粉体を得た。この顔料を用いて、以下の組成で実施例１と同様にボールミル分散を行い、分散液を作製した（これを分散液４とする）。
前記のチタニルフタロシアニン粉末 ６部
ポリビニルアセタール ４部
２−ブタノン ３２０部
【００８４】
比較例２
比較例１におけるボールミル分散時間を１２時間に変更した以外は比較例１と同様にして分散液を作製した（これを分散液５とする）。
【００８５】
比較例３
比較例１における結晶変換溶媒ならびに分散溶媒を２−ブタノンからテトラヒドロフランに変更した以外は比較例１と全く同様にして分散液を作製した（これを分散液６とする）。
【００８６】
比較例４
比較例３におけるボールミル分散時間を１２時間に変更した以外は比較例１と同様にして分散液を作製した（これを分散液７とする）。
【００８７】
上記実施例１、２、参考例１および比較例１〜４で作製した分散液（分散液１〜７）の平均粒径をＣＡＰＡ７００（堀場製作所社製）にて測定した。結果を表１に示す。また、各分散液を室温暗所にて１ヶ月静置保存し、分散液の様子を観察した。更に、分散液を乾固し、粉末とした後、その粉末のＸ線回折スペクトルを前記の方法で測定した。これらの結果も併せて表１に示す。
【００８８】
【表１】

表１より、分散液５、７は粒径が小さく、沈降性も良好であるが、結晶型が一部変化していることが分かる。また分散液１、２、３は、粒径も小さく、保存後においても安定した分散液であるっことが分かる。一方、分散液４、６は粒子が大きく、沈降性が大きいことが分かる。
【００８９】
実施例３、４および比較例５、６
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５には前記分散液５を用い、比較例６には前記分散液７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 ８部
【化１３】

塩化メチレン ８０部
【００９０】
このようにしてなる電子写真感光体を図５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２に示す。
【００９１】
【表２】

表２より、実施例３、４の電子写真感光体は繰返し使用後にも、安定した表面電位を維持していることが分かる。
【００９２】
実施例５、参考例２および比較例７、８
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、参考例２には前記分散液３を用い、比較例７には前記分散液４を用い、比較例８には前記分散液６用いた。
〔電荷輸送層塗工液〕
下記構造式の電荷輸送物質 ７部
【化１４】

ポリカーボネート １０部
塩化メチレン ８０部
【００９３】
実施例６、参考例３および比較例９、１０
実施例５、参考例２および比較例７、８で用いた分散液を室温暗所にて１ヶ月静置保存し、それぞれ実施例５、参考例２と同様にして感光体を作製した。
【００９４】
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）とした。連続して５０００枚の印刷を行い、初期および５０００枚目の画像を評価した。表３より分散液６、７を用いた場合（実施例５、６及び参考例２、３の感光体）には、繰り返し使用後および分散保存後にも良好な画像が得られることがわかる。
【００９５】
【表３】

【００９６】
実施例７
実施例５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５と全く同様にして感光体を作製した。
【００９７】
実施例８
実施例７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７と全く同様にして感光体を作製した。
〔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
【００９８】
実施例９
実施例７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７と全く同様にして感光体を作製した。
〔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
【００９９】
上記の実施例７〜９の各電子写真感光体を図４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。
【０１００】
【表４】

表４から実施例７〜９の電子写真感光体は特に優れた耐摩耗性を示していることがわかる。
【０１０１】
【発明の効果】
本発明によれば、特定の作製方法によって作製された分散液を用いて製造される感光体は、高感度を失うことなく繰り返し使用によっても帯電性の低下と残留電位の上昇を生じない安定な電子写真感光体である。また、長期の保存によっても上述の安定した特性を維持できる分散液が提供される。また、前記特性を維持したまま、耐摩耗性を向上した電子写真感光体が提供される。また、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方法が提供される。さらに、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】本発明で用いられる電子写真感光体の模式断面図。
【図２】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３】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４】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】本発明の代表的な電子写真装置を説明するための概略図。
【図７】実施例１で得られたウェットケーキの乾燥品のＸ線回折スペクトル。
【図８】実施例１により得られた分散液中のチタニルフタロシアン顔料のＸ線回折スペクトル。
【図９】比較例４で得られた分散液中のチタニルフタロシアニン顔料のＸ線回折スペクトル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a dispersion exhibiting high functions by a specific method, a dispersion for an electrophotographic photoreceptor using the dispersion, an electrophotographic photoreceptor produced using the dispersion, and an electrophotographic photoreceptor thereof. More specifically, the electrophotographic method used, the electrophotographic apparatus, and the process cartridge for the electrophotographic apparatus, and more particularly, the electrophotographic photosensitive member excellent in stability of the charging potential and the residual potential even after repeated use, and an abnormality using the same The present invention relates to an electrophotographic method with little image generation, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.
[0002]
[Prior art]
Organic pigments have been used as fillers 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 and uses have been created since they have been spotlighted as materials for organic photoelectric conversion devices.
[0003]
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.
[0004]
In order to prepare such a dispersion, various dispersers and dispersion systems have been proposed so far, and methods for increasing the dispersion efficiency have been devised. 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.
[0005]
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 is markedly improved 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.
[0006]
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.
[0007]
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.
[0008]
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 photoreceptors, it is empirically known in many photoreceptors that a decrease in chargeability and an increase in residual potential due to repeated use dominate the life characteristics of the photoreceptor, and titanyl phthalocyanine is also this 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 (photosensitive layer forming solution) that can stably produce a photoconductor having these characteristics for a long period of time.
[0009]
The organic photoreceptor is a so-called single-layer photoreceptor in which a coating solution for a photosensitive layer containing a charge generating material, a charge transporting 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 on a support 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.
[0010]
[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 a dispersion capable of stably producing a photoconductor having the above characteristics for a long period of time. Another object of the present invention is to provide a method for producing a dispersion having the above characteristics. 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.
[0011]
[Means for Solving the Problems]
The present invention has been devised as follows for organic pigments.
The dispersibility of the organic pigment can be roughly classified into the grindability and dispersion stability of the pigment. The latter is determined by factors such as the paintability of the pigment and the vehicle, the particle size, and the specific gravity difference between the pigment and the vehicle. On the other hand, the former is determined by the hardness of the pigment under a certain dispersion condition. In other words, the hardness of the pigment can be said to be the bulk density of the pigment.
The bulk density of a pigment is greatly influenced by the density of the pigment itself and the cohesive strength of the pigment. The minimum unit of the organic pigment particles is a primary particle, and interaction between particles is generated by intermolecular hydrogen bonding or the like to form secondary particles in which the primary particles are aggregated. The size of the primary particles is almost determined in the process of pigment synthesis unless a means for dissolving the pigment such as acid pasting is used. Since one secondary particle is an aggregate of primary particles, its state can be changed by a post-process of pigment synthesis. The bulk density of the pigment is determined by the packing strength of the secondary particles.
[0012]
In addition, as described above, organic pigments have recently been applied as photoelectric conversion materials, and materials that exhibit good characteristics in general have a strong cohesive force and a very strong packing property for secondary particles. For this reason, it is very difficult to produce a good dispersion. Even in the case of materials represented by the same chemical structural formula, there are many cases where only a specific crystal form exhibits a specific function. Such a specific crystal type may easily change due to simple physical / mechanical stress in addition to chemical stress. In such a case, it is not preferable to apply a lot of physical and mechanical stress such as dispersion, and the ability to easily disperse is an effective means for undoubtedly expressing a specific function.
[0013]
Furthermore, the present 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]
The present invention is a method for producing a pigment dispersion exhibiting good dispersion stability, and is a method for producing a dispersion while maintaining the crystallinity of the pigment used. The feature is a method for producing a dispersion without passing through the state of the pigment powder (heated and dried state) and maintaining the primary particles and the crystal form as much as possible.
Further, in the present invention, when a photoconductor using a dispersion prepared by the above technique is used in an electrophotographic process, the chargeability and photosensitivity are reduced in repeated use, which has been a problem in the past (increased residual potential). It has been found that a stable surface potential can be provided without causing any problems. As a result, it has been found that the occurrence of abnormal images such as background dirt or image density reduction can be suppressed, and the present invention has been completed.
[0015]
Therefore, according to the present invention, firstly, in the method of preparing a dispersion using an organic pigment prepared by a step in which the final step in pigment preparation is a crystal conversion step in which the crystal form is controlled by a wet method, There is provided a method for preparing a dispersion containing an organic pigment, wherein the crystal conversion step uses a dispersing means in combination.
[0016]
Secondly, in the preparation method, preparation of a dispersion containing the first organic pigment is characterized in that the pigment to be prepared undergoes crystal conversion and dispersion at the same time without passing through a drying step. A method is provided.
[0017]
Third, in the preparation method, there is provided a method for preparing a dispersion liquid containing the first organic pigment, wherein a resin is used in combination with a crystal conversion solvent.
[0018]
Fourth, there is provided a method for producing a dispersion containing an organic pigment according to any one of the first to third, wherein the organic pigment produced in the production method is a phthalocyanine pigment.
[0019]
  Fifth, the organic pigment produced by the above production method is at least characteristic X-ray (wavelength of CuKα).1.541ÅAnd a titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ° ± 0.2 °, and a method for producing a dispersion containing an organic pigment according to any one of the first to third items Is provided.
[0020]
Sixth, in a dispersion for an electrophotographic photoreceptor in which an organic pigment is dispersed in at least a solvent, the pigment contained in the dispersion is an organic whose crystal form is controlled by a wet method as the final step of pigment preparation. There is provided a dispersion for an electrophotographic photoreceptor, which is a pigment and is a pigment obtained by simultaneously performing crystal conversion and dispersion without passing through a drying step.
[0021]
  Seventh, the organic pigment contained in the dispersion contains at least characteristic X-rays (wavelengths) of CuKα.1.541ÅThe sixth electrophotographic photosensitive layer dispersion is provided, which is titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ° ± 0.2 °.
[0022]
Eighth, in an electrophotographic photosensitive member in which at least a photosensitive layer is provided on a conductive support, a dispersion containing an organic pigment for forming the photosensitive layer is converted into a wet type crystal form as a final step of pigment preparation. There is provided an electrophotographic photosensitive member, characterized in that the pigment is a dispersion obtained by simultaneously performing crystal conversion and dispersion without passing through a drying step.
[0023]
Ninth, the above-mentioned eighth electrophotographic photosensitive is characterized in that the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.
[0024]
Tenth, the ninth electrophotographic photosensitive member is characterized in that the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.
[0025]
Eleventh, in an electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and static elimination are repeated on an electrophotographic photosensitive member, the electrophotographic photosensitive member has a wet crystalline form as at least a final step of pigment preparation. A photosensitive layer prepared by using a dispersion containing an organic pigment which is controlled by a method and is subjected to crystal conversion and dispersion at the same time without passing through a drying step is provided on a conductive support. An electrophotographic method is provided.
[0026]
Twelfth, 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 at least a pigment. As a final process of production, a photosensitive layer produced by using a dispersion containing an organic pigment whose crystal type is controlled by a wet method and crystal transformation and dispersion are performed simultaneously without passing through a drying process is conducted. An electrophotographic apparatus is provided which is provided on a support.
[0027]
Thirteenth, a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has a crystal type controlled by a wet method at least as a final step of producing a pigment, and An electrophotography comprising a photosensitive layer prepared on a conductive support using a dispersion containing an organic pigment that has been subjected to crystal conversion and dispersion at the same time without undergoing a drying step. An apparatus process cartridge is provided.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
A method for obtaining a target crystal form (for example, titanyl phthalocyanine having a maximum diffraction peak of 27.2 ° ± 0.2 ° with a black angle 2θ) in the present invention is a method by a known method, washing, Examples include a method of changing crystals during the purification process and a method of providing a crystal conversion step. Further, among the methods for forming a crystal conversion step, a general conversion method using a solvent and mechanical load, and titanyl phthalocyanine is dissolved in sulfuric acid, and the solution is poured into water to form amorphous crystals. The sulfuric acid pasting method which performs conversion is mentioned.
Such an amorphous crystal can be converted into a specific crystal form by treatment with an organic solvent as described above, and in general, the particle size is very fine in an amorphous crystal state. is there. In general, after a crystal conversion step, a drying step is performed to obtain a pigment having a predetermined crystal type, and this is dispersed in an appropriate solvent (a resin may be used in combination) using an appropriate disperser. Is made.
[0029]
As described above, high-performance pigments used in recent years are often agglomerated by this drying step and often become large lumps after drying. In order to prepare a dispersion liquid having a small particle diameter using such a pigment, it is necessary to disperse using a small-sized medium. It is necessary to coarsely pulverize to the size, or to considerably increase the dispersion time. At this time, a physical (mechanical) stress necessary for pulverizing (or dispersing) is likely to change the crystal form of the pigment. For this reason, although the desired crystal form is obtained by processing to change the crystal, it is often the case that the crystal form is partially changed in the state of the dispersion (photosensitive member). In addition, in the state where the dispersion is suppressed so as not to change the crystal form, the coating particle defects are likely to occur when the pigment particle size in the dispersion is large, which may produce an abnormal image.
[0030]
The present inventor has found several points as a result of examination in view of such drawbacks. That is,
(1) Amorphous crystals just subjected to sulfuric acid pasting treatment have very small particles.
(2) When the pigment subjected to the sulfuric acid pasting treatment is dried, the particles become large.
(3) When the pigment subjected to the sulfuric acid pasting treatment is crystal-converted in a wet state, the particles should remain small.
(4) When the crystal-converted pigment is dried, the particles become large.
(5) Crystal conversion should be sufficiently performed even if a binder resin coexists with the processing solvent.
(6) Impurities generated by the sulfuric acid pasting process are considerably removed during crystal conversion. This impurity should be removed by solvent washing (even rinsing is possible)
Etc.
[0031]
From the above viewpoint, the present inventor has led to the point that the most important point is that the amorphous crystal pigment subjected to the sulfuric acid pasting treatment is subsequently subjected to crystal conversion (simultaneously using a dispersing means) without drying. The present invention has been completed.
[0032]
When preparing the dispersion according to the present invention, the method is slightly different depending on the purity of the pigment subjected to the sulfuric acid pasting treatment. When the purity is sufficiently high, the pigment (wet cake state) subjected to the sulfuric acid pasting treatment is used together with a crystal conversion solvent (a resin is used if necessary. In this case, the resin is dissolved in the solvent in advance. The dispersion is prepared by simultaneously carrying out crystal conversion and dispersion while maintaining the small size of the particles while using the dispersing means together. Any known method (ball mill, bead mill, sand mill, attritor, etc.) can be used as the dispersing means at this time.
If the purity is not so high, add a filtration step after crystal conversion (but do not dry), put it in a crystal conversion solvent (with resin if necessary) in a wet state, and use dispersion means together Then, the crystal conversion is continued. In this case, it is wise not to use a binder resin at the first crystal conversion.
[0033]
  The dispersion prepared according to the present invention is a dispersion containing at least a pigment (particularly an organic pigment). This dispersion is a dispersion used to form a coating film by a wet method. More specifically, it is a dispersion used for forming a charge generation layer of an electrophotographic photoreceptor. The method for preparing the dispersion is as described above, but the pigment used is effective for those having many crystal forms (crystal polymorphs). Typical examples include phthalocyanines, including titanyl phthalocyanine (particularly the characteristic X-ray (wavelength of CuKα)).1.541ÅIn particular, titanyl phthalocyanine) having a maximum diffraction peak with a Bragg angle 2θ of 27.2 ° ± 0.2 ° is effective. A predetermined crystal type pigment, a selected solvent, and, if necessary, a binder resin are used in the dispersion.
[0034]
In addition to phthalocyanines, other charge generation materials can also be used as pigments. Typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinone condensation. Polycyclic compounds, squaric acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes and the like are used.
[0035]
Next, the electrophotographic photosensitive member produced according to the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an 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. 2 and FIG. 3 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.
[0036]
The conductive support 31 has a volume resistance of 10^TenFilms having conductivity of Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxides such as tin oxide, indium oxide, etc. are deposited or sputtered. Shaped or cylindrical plastic, paper-coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. and surface after cutting, superfinishing, polishing, etc. Treated tubes and the like can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Laid-Open No. 52-36016 can be used as the conductive support 31.
[0037]
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.
[0038]
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.
[0039]
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.
[0040]
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.
[0041]
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 of the coating solution, methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and 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.
[0042]
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.
[0043]
Charge transport materials include hole transport materials and electron transport materials. Examples of the charge transport material include chloranil, 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.
[0044]
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.
[0045]
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.
[0046]
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.
[0047]
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.
[0048]
[Chemical 1]

Where R₁, R₂, R_ThreeEach independently represents a substituted or unsubstituted alkyl group or a halogen atom, R_FourIs a hydrogen atom or a substituted or unsubstituted alkyl group, R_Five, R₆Is 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 2]

Where R₁₀₁, R₁₀₂Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, -O-, -S-, -SO-, -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, R₁₀₃, R₁₀₄Represents a substituted or unsubstituted alkyl group or aryl group. Where R₁₀₁And R₁₀₂, R₁₀₃And R₁₀₄May be the same or different.
[0049]
[Formula 4]

Where R₇, R₈Is a substituted or unsubstituted aryl group, Ar₁, Ar₂, Ar_ThreeRepresent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0050]
[Chemical formula 5]

Where R₉, R_TenIs a substituted or unsubstituted aryl group, Ar_Four, Ar_Five, Ar₆Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0051]
[Chemical 6]

Where R₁₁, R₁₂Is a substituted or unsubstituted aryl group, Ar₇, Ar₈, Ar₉Are 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).
[0052]
[Chemical 7]

Where R₁₃, R₁₄Is a substituted or unsubstituted aryl group, Ar_Ten, Ar₁₁, Ar₁₂Are the same or different arylene groups, X₁, X₂Represents a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j, and n are the same as in the case of equation (1).
[0053]
[Chemical 8]

Where R₁₅, R₁₆, R₁₇, R₁₈Is a substituted or unsubstituted aryl group, Ar₁₃, Ar₁₄, Ar₁₅, Ar₁₆Are the same or different arylene groups, Y₁, Y₂, Y_ThreeRepresents 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).
[0054]
[Chemical 9]

Where R₁₉, R₂₀Represents a hydrogen atom, a substituted or unsubstituted aryl group, and R₁₉And R₂₀May form a ring. Ar₁₇, Ar₁₈, Ar₁₉Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0055]
[Chemical Formula 10]

Where R_{twenty one}Is a substituted or unsubstituted aryl group, Ar₂₀, 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).
[0056]
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}, Ar₂₆, Ar₂₇, Ar₂₈Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0057]
Embedded image

Where R₂₆, R₂₇Is a substituted or unsubstituted aryl group, Ar₂₉, Ar₃₀, Ar₃₁Represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).
[0058]
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 based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 1 weight relative to the binder resin. % Is appropriate.
[0059]
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 dissolving or dispersing the charge transport material and the binder resin in an appropriate solvent in the above-mentioned dispersion liquid, and applying and drying the solution. 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.
[0060]
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 generating material is preferably 5 to 40 parts by weight, and the amount of the charge transporting 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.
[0061]
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, it may be a resin having a 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. In addition, a fine powder pigment of a metal oxide which can be 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.
[0062]
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 A1.₂O_ThreeAnodic oxidation, organic materials such as polyparaxylylene (parylene), and SiO₂, SnO₂, TiO₂, ITO, CeO₂A 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.
[0063]
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 manufacturing method can be used as the protective layer.
[0064]
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.
[0065]
Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings.
[0066]
FIG. 4 is a schematic view 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.
[0067]
In FIG. 4, the photosensitive member 1 is provided with 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. For 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.
[0068]
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.
[0069]
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.
[0070]
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 in combination with light irradiation in addition to the process shown in FIG.
[0071]
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.
[0072]
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.
[0073]
FIG. 5 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. 5, the photoconductor 21 (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.
[0074]
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. 5, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or image exposure and discharge exposure may be performed from the support side.
[0075]
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.
[0076]
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. The photosensitive member 16 has a TiOPc photosensitive layer that gives a specific X-ray diffraction spectrum on a conductive support.
[0077]
【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.
[0078]
Example 1
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)
52.5 parts of fuclodinitrile and 400 parts of 1-chloronaphthalene are stirred and mixed, and 19 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 42.2 parts of a crude titanyl phthalocyanine pigment. The obtained crude titanyl phthalocyanine pigment washed with hot water was stirred in 100 parts of 96% sulfuric acid at 3 to 5 ° C., dissolved and filtered. The obtained sulfuric acid solution was dropped into 3500 parts of ice water with stirring, the precipitated crystals were filtered, and then washed repeatedly with water until the washing solution became neutral to obtain a titanyl phthalocyanine pigment wet cake. 320 parts of 2-butanone in which 6 parts of this wet cake and 4 parts of butyral resin were dissolved were put into a glass pot containing zirconia balls having a diameter of 2 mm, and dispersed for 2 hours by a ball mill to obtain a dispersion (this is a dispersion liquid). 1).
[0079]
The obtained wet cake and the dispersion part after water washing were dried, and the X-ray diffraction spectrum of the powder 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,
[0080]
The X-ray diffraction spectrum of the dried product of the wet cake is shown in FIG. It can be seen that the pigment in the obtained wet cake has an irregular shape.
Further, an X-ray diffraction spectrum of the titanyl phthalocyanine pigment in the dispersion obtained from Example 1 is shown in FIG. It can be seen that the obtained titanyl phthalocyanine pigment has a crystal form with a maximum diffraction peak at a Bragg angle of 2θ of 27.2 ° ± 0.2 °.
[0081]
Example 2
Example 1 except that 6 parts of the wet cake obtained in Example 1 after the sulfuric acid pasting treatment and 320 parts of tetrahydrofuran in which 4 parts of butyral resin were dissolved were dispersed in a bead mill dispersing machine containing zirconia beads having a diameter of 0.2 mm. A dispersion was prepared in exactly the same manner as (Dispersion 2).
[0082]
Reference example 1
  The wet cake obtained in Example 1 after 6 parts of wet cake and 320 parts of 2-butanone (but not adding a butyral resin) were ball milled under the same conditions as in Example 1, and the dispersion was used in Example 1. A dispersion was prepared in the same manner as in Example 1 except that 4 parts of butyral resin was dissolved later (this is referred to as Dispersion 3).
[0083]
Comparative Example 1
6 parts of the wet cake obtained in Example 1 after the sulfuric acid pasting treatment was crystal-converted with 320 parts of 2-butanone (no butyral resin added), filtered, and then vacuum-dried at 80 ° C. for 1 day. A pigment powder was obtained. Using this pigment, ball mill dispersion was performed in the same manner as in Example 1 with the following composition to prepare a dispersion (this is referred to as dispersion 4).
6 parts of the above titanyl phthalocyanine powder
4 parts of polyvinyl acetal
2-butanone 320 parts
[0084]
Comparative Example 2
A dispersion was prepared in the same manner as in Comparative Example 1 except that the ball mill dispersion time in Comparative Example 1 was changed to 12 hours (this is referred to as Dispersion 5).
[0085]
Comparative Example 3
A dispersion was prepared in the same manner as in Comparative Example 1 except that the crystal conversion solvent and the dispersion solvent in Comparative Example 1 were changed from 2-butanone to tetrahydrofuran (this is referred to as Dispersion 6).
[0086]
Comparative Example 4
A dispersion was prepared in the same manner as in Comparative Example 1 except that the ball mill dispersion time in Comparative Example 3 was changed to 12 hours (this is referred to as Dispersion 7).
[0087]
  Example 1 above2, Reference Example 1And the average particle diameter of the dispersion liquid (dispersion liquids 1-7) produced in Comparative Examples 1 to 4 was measured with CAPA700 (manufactured by Horiba, Ltd.). The results are shown in Table 1. In addition, each dispersion was stored at room temperature in a dark place for 1 month, and the state of the dispersion was observed. Further, the dispersion was dried to form a powder, and the X-ray diffraction spectrum of the powder was measured by the above method. These results are also shown in Table 1.
[0088]
[Table 1]

From Table 1, it can be seen that the dispersions 5 and 7 have small particle sizes and good sedimentation properties, but the crystal form is partially changed. Further, it can be seen that the dispersions 1, 2, and 3 have small particle diameters and are stable dispersions even after storage. On the other hand, it can be seen that the dispersions 4 and 6 have large particles and large sedimentation properties.
[0089]
Example3, 4And Comparative Examples 5 and 6
  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]
  Example3In the above example, the dispersion 1 was used.4The dispersion 2 is used for the comparative example 5, and the dispersion is used for the comparative example 5.5In Comparative Example 6, the dispersion 7 was used.
[Charge transport layer coating solution]
  10 parts of polycarbonate
  8 parts of charge transport material of the following structural formula
Embedded image

  80 parts of methylene chloride
[0090]
The electrophotographic photosensitive member thus formed is mounted on the electrophotographic process shown in FIG. 5 (no exposure before cleaning), and the image exposure light source is a 780 mm semiconductor laser (image writing by a polygon mirror). A surface potential meter probe was inserted so that the surface potential of the photoreceptor could be measured. 5000 sheets were continuously printed, and the surface potentials of the image exposure part and the image non-exposure part at that time were measured initially and after 5000 sheets. The results are shown in Table 2.
[0091]
[Table 2]

From Table 2, Examples3, 4It can be seen that the electrophotographic photoreceptor of FIG. 1 maintains a stable surface potential even after repeated use.
[0092]
Example5,Reference example 2And Comparative Examples 7 and 8
  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]
  Example5The dispersion 1 is used forReference example 2The dispersion 3 was used for the above, the dispersion 4 was used for the comparative example 7, and the dispersion 6 was used for the comparative example 8.
[Charge transport layer coating solution]
  7 parts of charge transport material with the following structural formula
Embedded image

  10 parts of polycarbonate
  80 parts of methylene chloride
[0093]
Example6,Reference example 3And Comparative Examples 9 and 10
  Example5,Reference example 2The dispersions used in Comparative Examples 7 and 8 were stored at room temperature in a dark place for 1 month.5,Reference example 2A photoreceptor was prepared in the same manner as described above.
[0094]
  The electrophotographic photoreceptor thus constructed was mounted on the electrophotographic process cartridge shown in FIG. 6 and then mounted on the image forming apparatus. The image exposure light source was a 780 mm semiconductor laser (image writing by a polygon mirror). 5000 sheets were printed continuously, and the initial and 5000th images were evaluated. From Table 3, when dispersions 6 and 7 were used (Examples)5, 6 and Reference Examples 2, 3It can be seen that a good image can be obtained after repeated use and after dispersion storage.
[0095]
[Table 3]

[0096]
Example7
  Example5Except for changing the support from electroformed nickel belt to aluminum cylinder in Example5A photoconductor was prepared in the same manner as described above.
[0097]
Example8
  Example7Except that the charge transport layer coating solution was changed to the following composition, Example7A photoconductor was prepared in the same manner as described above.
[Charge transport layer coating solution]
  10 parts of polymer charge transport material of the following structural formula
Embedded image

  100 parts methylene chloride
[0098]
Example9
  Example7Except that the charge transport layer coating solution was changed to the following composition, Example7A photoconductor was prepared in the same manner as described above.
[Charge transport layer coating solution]
  10 parts of polymer charge transport material of the following structural formula
Embedded image

  100 parts methylene chloride
[0099]
  Example above7-94 are mounted on the electrophotographic process shown in FIG. 4 (however, the image exposure light source is an LD that emits light at 780 nm), and 10,000 sheets are printed continuously. And evaluated after 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.
[0100]
[Table 4]

Examples from Table 47-9It can be seen that the electrophotographic photoreceptor of the present invention exhibits particularly excellent wear resistance.
[0101]
【The invention's effect】
According to the present invention, a photoconductor manufactured using a dispersion prepared by a specific manufacturing method is stable without causing a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity. An electrophotographic photoreceptor. In addition, a dispersion that can maintain the above-described stable characteristics even after long-term storage is provided. In addition, an electrophotographic photoreceptor having improved wear resistance while maintaining the above characteristics is provided. In addition, a stable electrophotographic method that does not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity is provided. Furthermore, there are provided 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.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an electrophotographic photosensitive member used in the present invention.
FIG. 2 is a schematic cross-sectional view of another electrophotographic photosensitive member used in the present invention.
FIG. 3 is a schematic cross-sectional view of still another electrophotographic photosensitive member used in the present invention.
FIG. 4 is a schematic diagram for explaining an electrophotographic process and an electrophotographic apparatus of 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 a representative electrophotographic apparatus of the present invention.
7 is an X-ray diffraction spectrum of a dried product of the wet cake obtained in Example 1. FIG.
8 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment in the dispersion obtained in Example 1. FIG.
9 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment in the dispersion obtained in Comparative Example 4. FIG.

Claims (8)

In a method for producing a dispersion in which titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of at least 27.2 ° ± 0.2 ° with respect to a characteristic X-ray (wavelength 1.541 波長) of CuKα is dispersed,
The titanyl phthalocyanine wet cake obtained by the sulfuric acid pasting treatment is dispersed in 2-butanone or tetrahydrofuran in which the water-insoluble butyral resin is dissolved, without passing through a drying step, and crystals A method for producing a dispersion liquid, characterized by being converted. In a dispersion in which titanyl phthalocyanine having a maximum diffraction peak with a Bragg angle 2θ of at least 27.2 ° ± 0.2 ° with respect to a characteristic X-ray (wavelength 1.541Å) of CuKα is dispersed,
The titanyl phthalocyanine wet cake obtained by the sulfuric acid pasting treatment is dispersed in 2-butanone or tetrahydrofuran in which the water-insoluble butyral resin is dissolved, without passing through a drying step, and crystals A dispersion characterized by being converted. In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support,
An electrophotographic photosensitive member provided with the photosensitive layer using the dispersion according to claim 2.   4. The electrophotographic photosensitive member according to claim 3, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.   5. The electrophotographic photoreceptor according to claim 4, wherein the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.   An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and static elimination are repeated on the electrophotographic photosensitive member according to claim 3.   An electrophotographic apparatus comprising at least a charging unit, an image exposure unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and the electrophotographic photosensitive member according to any one of claims 3 to 5.   A process cartridge for an electrophotographic apparatus comprising at least the electrophotographic photosensitive member according to any one of claims 3 to 5.

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