JP4159696B2 - Method for producing dispersion, dispersion for electrophotographic photosensitive member, electrophotographic photosensitive member, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Description

式中、Ｒ₁、Ｒ₂及びＲ₃はそれぞれ独立して置換若しくは無置換のアルキル基又はハロゲン原子を、Ｒ₄は水素原子又は置換若しくは無置換のアルキル基を、Ｒ₅及びＲ₆は置換若しくは無置換のアリール基を、夫々表す。ｏ、ｐ及びｑはそれぞれ独立して０〜４の整数を表し、ｋ及びｊは組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９である。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、又は下記一般式で表される２価基を表す。
【化２】

式中、Ｒ₁₀₁及びＲ₁₀₂は各々独立して置換若しくは無置換のアルキル基、アリール基又はハロゲン原子を表す。ｌ及びｍは０〜４の整数を表し、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状若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。）、又は
【化３】

（式中、ａは１〜２０の整数を、ｂは１〜２０００の整数を、夫々表し、Ｒ₁₀₃及びＲ₁₀₄は置換若しくは無置換のアルキル基又はアリール基を表す。）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】
（２）一般式（２）で表されるポリカーボネート
【化４】

式中、Ｒ₇及びＲ₈は置換若しくは無置換のアリール基を表し、Ａｒ₁、Ａｒ₂及びＡｒ₃は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００４８】
（３）一般式（３）で表されるポリカーボネート
【化５】

式中、Ｒ₉及びＲ₁₀は置換若しくは無置換のアリール基を表し、Ａｒ₄、Ａｒ₅及びＡｒ₆は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００４９】
（４）一般式（４）で表されるポリカーボネート
【化６】

式中、Ｒ₁₁及びＲ₁₂は置換若しくは無置換のアリール基を、Ａｒ₇、Ａｒ₈及びＡｒ₉は同一又は異なるアリレン基を、ｐは１〜５の整数を、夫々表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５０】
（５）一般式（５）で表されるポリカーボネート
【化７】

式中、Ｒ₁₃及びＲ₁₄は置換若しくは無置換のアリール基を、Ａｒ₁₀、Ａｒ₁₁及びＡｒ₁₂は同一又は異なるアリレン基を、夫々表し、Ｘ₁及びＸ₂は置換若しくは無置換のエチレン基、又は置換若しくは無置換のビニレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５１】
（６）一般式（６）で表されるポリカーボネート
【化８】

式中、Ｒ₁₅、Ｒ₁₆、Ｒ₁₇及びＲ₁₈は置換若しくは無置換のアリール基を、Ａｒ₁₃、Ａｒ₁₄、Ａｒ₁₅及びＡｒ₁₆は同一又は異なるアリレン基を、夫々表し、Ｙ₁、Ｙ₂及びＹ₃は単結合、置換若しくは無置換のアルキレン基、置換若しくは無置換のシクロアルキレン基、置換若しくは無置換のアルキレンエーテル基、酸素原子又は硫黄原子、又はビニレン基を表し、同一であっても異なっていてもよい。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５２】
（７）一般式（７）で表されるポリカーボネート
【化９】

式中、Ｒ₁₉及びＲ₂₀は水素原子又は置換若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及びＡｒ₁₉は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５３】
（８）一般式（８）で表されるポリカーボネート
【化１０】

式中、Ｒ₂₁は置換若しくは無置換のアリール基を、Ａｒ₂₀、Ａｒ₂₁、Ａｒ₂₂及びＡｒ₂₃は同一又は異なるアリレン基を、夫々表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５４】
（９）一般式（９）で表されるポリカーボネート
【化１１】

式中、Ｒ₂₂、Ｒ₂₃、Ｒ₂₄及びＲ₂₅は置換若しくは無置換のアリール基を、Ａｒ₂₄、Ａｒ₂₅、Ａｒ₂₆、Ａｒ₂₇及びＡｒ₂₈は同一又は異なるアリレン基を、夫々表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）の場合と同じである。
【００５５】
（１０）一般式（１０）で表されるポリカーボネート
【化１２】

式中、Ｒ₂₆及びＲ₂₇は置換若しくは無置換のアリール基を、Ａｒ₂₉、Ａｒ₃₀及びＡｒ₃₁は同一又は異なるアリレン基を、夫々表す。Ｘ、ｋ、ｊ及びｎは、一般式（１）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。単層感光層の形成には、上述した特定の方法によって作製された顔料を結着樹脂中に分散した分散液が使用できる。即ち、単層感光層は、電荷発生物質、電荷輸送物質及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。更に、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、更に好ましくは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。
【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。
【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及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。
【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（好ましくは特定のＸ線回折スペクトルを与えるＴｉＯＰｃ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及びブレード１５により、感光体より除去される。クリーニングは、クリーニングブラシ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（好ましくは特定のＸ線回折スペクトルを与えるＴｉＯＰｃ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、及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成膜した感光層（好ましくは特定の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。
【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）
フタロジニトリル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、次いで１−クロロナフタレンで粉体が青色になるまで洗浄し、次にメタノールで数回洗浄し、更に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、次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部を更に加え撹拌し、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。片方のストックタンクからもう一方のストックタンクに分散室を通して送液する分散操作（パス分散と呼ぶ）を１回行った。
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。これを分散液１とする。
【００８０】
実施例２
実施例１におけるパス分散を２回行った以外は、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。
【００８１】
実施例３
実施例１におけるパス分散を４回行った以外は、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３とする。
【００８２】
比較例１ 実施例１におけるパス分散を行わず、始めから弁を調節して片側のストックタンクのみを使用して循環分散（循環分散時間３０分）を行った。これを分散液４とする。
【００８３】
比較例２ 実施例１におけるパス分散を行わず、始めから弁を調節して片側のストックタンクのみを使用して循環分散（循環分散時間１８０分）を行った。これを分散液５とする。
【００８４】
比較例３ 実施例１における分散条件において、ブチラール樹脂を添加せずに分散を行い、分散後にブチラール樹脂を溶解した。これを分散液６とする。
【００８５】
上記のように作製した分散液を以下のように評価した。平均粒径・粒度分布は堀場製作所：ＣＡＰＡ７００にて測定した。粒度分布の評価は、全体の分布に対する各粒子サイズの範囲を体積分率で算出される数値を持って評価した。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。
【００８６】
【表１】

表１より、分散液１〜３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。
【００８７】
次いで、塗工性を評価するため直径３０ｍｍのアリミニウムシリンダーに浸漬塗工法により、先述の分散液１〜４を塗工した。塗膜の状態を目視にて評価を行った。結果を表２に示す。
【００８８】
【表２】

表２により、分散液１〜３を用いた場合には塗膜欠陥のない良好な塗膜が得られることが分かる。
【００８９】
保存性の試験として、分散液１〜４を室温暗所にて１ヶ月間静置保存し、保存後の分散液の状態を観察した。結果を表３に示す。
【００９０】
【表３】

表３の結果から、分散液１〜３は保存性・分散安定性にも優れていることが分かる。
【００９１】
実施例４〜６及び比較例４、５
電鋳ニッケルベルト上に下記組成の下引き層塗工液、電荷発生層塗工液、及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。
【００９２】
〔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
【００９３】
〔電荷発生層塗工液〕
前記分散液１〜５をそれぞれ用いた。
【００９４】
〔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 ７．５部
【化１３】

塩化メチレン ８０部
【００９５】
このようにして得られた電子写真感光体を図６に示す電子写真プロセス（但し、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８０００枚の印刷を行い、その時の画像評価を行った。結果を表４に示す。
【００９６】
【表４】

分散液４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。これにより異常画像の発生が認められた。また、分散液５を用いた感光体は、繰り返し使用後に、画像濃度の低下を生じた。表４より分散液１〜３を用いた感光体は、初期及び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。
【００９７】
実施例７、８及び比較例６
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。
【００９８】
〔電荷発生層塗工液〕
実施例７には前記分散液１を用い、実施例８には前記分散液２を用い、比較例６には前記分散液５を用いた。
【００９９】
〔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
【０１００】
このようにして得られた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６０００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６０００枚後に測定した結果を表５に示す。
【０１０１】
【表５】

表５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。
【０１０２】
実施例９
実施例４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４と全く同様にして感光体を作製した。
【０１０３】
実施例１０
実施例４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４と全く同様にして感光体を作製した。
【０１０４】
〔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
【０１０５】
実施例１１
実施例４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４と全く同様にして感光体を作製した。
【０１０６】
〔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
【０１０７】
上記の実施例９〜１１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（但し、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６に示す。
【０１０８】
【表６】

表４から実施例１０及び１１の電子写真感光体は、特に耐摩耗性を示していることがわかる。
【０１０９】
【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、且つ結晶型を変えることない分散液を作製する方法が提供され、この方法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、且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及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である。
【図２】本発明で用いられる電子写真感光体の模式断面図である。
【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である。
【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である。
【図５】本発明の電子写真プロセス及び電子写真装置を説明するための概略図である。
【図６】本発明の電子写真プロセス及び電子写真装置を説明するための概略図である。
【図７】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である。
【図８】本発明の顔料製造例により得られるチタニルフタロシアン顔料のＸ線回折スペクトルである。
【符号の説明】
１ 感光体
２ 除電ランプ
３ 帯電チャージャ
４ イレーサ
５ 画像露光部
６ 現像ユニット
７ 転写前チャージャ
８ レジストローラ
９ 転写紙
１０ 転写チャージャ
１１ 分離チャージャ
１２ 分離爪
１３ クリーニング前チャージャ
１４ ファーブラシ
１５ クリーニングブレード
１６ 感光体
１７ 帯電チャージャ
１８ クリーニングブラシ
１９ 画像露光部
２０ 現像ローラ
２１ 感光体
２２ａ、２２ｂ 駆動ローラ
２３ 帯電チャージャ
２４ 像露光源
２５ 転写チャージャ
２６ クリーニング前露光部
２７ クリーニングブラシ
２８ 除電光源
３１ 導電性支持体
３３ 感光層
３５ 電荷発生層
３７ 電荷輸送層
５１ 分散室
５２ モータ
５３Ａ、５３Ｂ ストックタンク
５４Ａ、５４Ｂ 撹拌機
５５ ポンプ
５８ 三方弁
５９ 三方弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preparing a dispersion containing an organic pigment, a dispersion for an electrophotographic photosensitive member using the dispersion, an electrophotographic photosensitive member made using the dispersion, and an electrophotography using the electrophotographic photosensitive member. The present invention relates to a method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus. More specifically, a method of preparing a dispersion liquid without changing the crystal form of an organic pigment, a dispersion liquid for an electrophotographic photoreceptor using the dispersion liquid, and a charged potential and a residual charge of the photoreceptor also by repeated use made using the dispersion liquid. The present invention relates to an electrophotographic photoreceptor excellent in potential stability, an electrophotographic method using the same, and an electrophotographic method with less abnormal image generation, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.
[0002]
[Prior art]
Organic pigments have been used as paint fillers 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 is almost no approach 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 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.
[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, 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. Is extremely important and useful.
[0008]
In the organic pigment as described above, a specific crystal structure often exhibits specific characteristics. For example, TiOPc is a characteristic X-ray of CuKα which is an unstable crystal type (metastable state) rather than a stable crystal called A type (β phase) or B type (α phase) ( 1.541 wavelength It is known that a material having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 ° is very sensitive.
[0009]
Since this material is in a metastable state, the crystal form is known to easily transfer due to physical stress such as grinding and dispersion, and the change in crystal form is reduced by conserving dispersion. The method is taken. According to this method, the pigment particle size in the dispersion is inevitably large. On the other hand, a dip coating method is generally used as a method for coating a photoconductor, but when a dispersion liquid having a large particle size is used, there is a drawback that coating film defects are likely to occur.
From these points, there has been a demand for a method for producing a dispersion having a sufficiently stable dispersion (fine particle size) and a stable crystal type.
[0010]
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 a decrease in chargeability and an increase in residual potential due to repeated use dominate the lifetime characteristics of photoconductors. 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 a dispersion (photosensitive layer forming solution) capable of stably producing a photoconductor having these characteristics for a long period of time.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for efficiently producing a dispersion when producing a dispersion using an organic pigment. Another object is to provide a method for producing a dispersion having a fine particle size while maintaining the specific crystal form of an organic pigment having a crystal polymorphism. Another object is to provide a method for producing a dispersion that can maintain specific characteristics stably for a long period of time.
Still another 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 is to provide an electrophotographic photosensitive member having improved wear resistance while maintaining the above characteristics. Still 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 a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity.
[0012]
[Means for Solving the Problems]
As described above, organic pigments play an important role as photocarrier generating materials for electrophotographic photoreceptors. 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. From this point of view, it is preferable that the organic pigment as the charge generating material has a narrow particle size distribution and a particle size as small as possible in the dispersion for forming the photosensitive layer (charge generating 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.
[0013]
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, but a minimum amount of coating solution is required even when a small number of coatings are applied. This minimum required amount is extremely large compared to other coating methods such as spraying and nozzle coating.
[0014]
Various methods for dispersing organic pigments have been proposed, but some limitations arise when producing a large amount of dispersion. That is, in ball mills, vibration mills, etc., the pot capacity 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.
[0015]
Such a system is generally designed to have a small dispersion chamber capacity 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 some liquids pass through the dispersion chamber many times, they 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).
[0016]
As described above, the present inventors have a very preferable idea of the circulation and dispersion system itself, 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 out that this is a flaw. In order to improve this point, all the liquids to be dispersed are passed through the dispersion chamber the same number of times (time), so that the dispersion efficiency is dramatically improved and the crystal type has a stable and uniform particle size distribution. And found that a dispersion can be prepared.
[0017]
In order to make the above method concrete, the present inventors removed the concept of circulation of a circulation system that has been generally used in recent years, and made the passage of the liquid to be dispersed one-way through the dispersion chamber before passing. It has been found that the liquid can be achieved by a method in which the passage time (number of times) of the entire liquid is completely equal by preventing the liquid of the liquid and the liquid after the passage from being absolutely mixed, and the present invention has been completed.
[0018]
In addition, the present inventors have good film formability and stable electrostatic characteristics by using a dispersion liquid having a stable crystal type and a uniform particle size distribution produced by using the above technique. It has been found that an electrophotographic photosensitive member is formed. That is, a photoreceptor using this dispersion is stable without causing a decrease in chargeability and a decrease in photosensitivity (an increase in residual potential) in repeated use, which has been a problem in the past, when used in an electrophotographic process. It was found that it provides a surface potential. 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.
[0019]
Therefore, according to the present invention, first, in a method for producing a dispersion in which an organic pigment is dispersed by passing a solvent containing an organic pigment through a dispersion chamber containing a dispersion medium, all the solvents are used for the same time. A method for producing a dispersion characterized by passing through a dispersion chamber is provided. Second, in a device in which at least one stock tank is connected to both ends of the dispersion chamber by piping, and a pump capable of feeding a solvent between the dispersion chamber and at least one stock tank is arranged on one side The method for producing a dispersion liquid according to the first aspect is characterized in that the dispersion is performed in a state where the solvent is passed in a one-way manner from the stock tank to the other stock tank. Is done. Third, the method for producing a dispersion liquid described in the first aspect is provided, wherein the liquid before and after passing through the dispersion chamber is separated, and a solvent having a different number of passes through the dispersion chamber is not mixed. The Fourth, the method for producing a dispersion liquid according to any one of the first to third aspects, wherein the organic pigment is a phthalocyanine pigment. Fifth, the method for producing a dispersion liquid according to any one of the first to third aspects, wherein the organic pigment is titanyl phthalocyanine. Sixth, the organic pigment is at least CuKα characteristic X-ray ( 1.541 wavelength The dispersion method according to any one of the first to third aspects is provided, which is titanyl phthalocyanine having a maximum diffraction peak with a Bragg angle 2θ of 27.2 ± 0.2 °. . Seventh, there is provided the method for producing a dispersion described in any one of the first to sixth, wherein a resin is used in the solvent.
[0020]
Eighth, there is provided a dispersion for an electrophotographic photoreceptor produced by the method described in any one of the first to seventh.
[0021]
Ninth, in an electrophotographic photosensitive member having a photosensitive layer in which at least an organic pigment is dispersed on a conductive support, a dispersion containing an organic pigment for forming the photosensitive layer is a dispersion containing a dispersion medium. An electrophotography, wherein the solvent is dispersed by a method in which an organic pigment is dispersed by passing a solvent containing an organic pigment through the chamber, and the solvent is dispersed so that all of the solvent passes through the dispersion chamber for the same time. A photoreceptor is provided. Tenth, in an electrophotographic photosensitive member having a photosensitive layer in which at least an organic pigment is dispersed on a conductive support, a dispersion containing an organic pigment for forming the photosensitive layer is at least at both ends of the dispersion chamber. One or more stock tanks are connected by piping, and a pump is installed that can send solvent between the dispersion chamber and at least one stock tank. From one stock tank to the other stock tank A ninth dispersion characterized in that it is a dispersion in which the solvent passes through the dispersion chamber in a one-way manner so that the solvent having different numbers of passages does not mix. The electrophotographic photoreceptor described in 1) is provided. Eleventh, the electrophotographic photosensitive member described in the ninth or tenth aspect is provided, wherein the organic pigment contained in the electrophotographic photosensitive member is a phthalocyanine pigment. Twelfth, the electrophotographic photosensitive member described in the ninth or tenth aspect is provided, wherein the organic pigment contained in the electrophotographic photosensitive member is titanyl phthalocyanine. Thirteenth, the organic pigment contained in the electrophotographic photoreceptor is at least a characteristic X-ray of CuKα ( 1.541 wavelength The electrophotographic photosensitive member described in the ninth or tenth aspect is a titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 °. Fourteenth, the electrophotographic photosensitive member according to any one of the ninth to thirteenth aspects is provided, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer. Fifteenth, the electrophotographic photosensitive member according to the fourteenth aspect, wherein the charge transporting layer of the electrophotographic photosensitive member contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain. Is provided.
[0022]
Sixteenth, in an electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeated on an electrophotographic photosensitive member, the electrophotographic photosensitive member has at least one stock at both ends of a dispersion chamber. A tank is connected by piping, and a pump that can send solvent between the dispersion chamber and at least one of the stock tanks is installed, and the dispersion chamber passes from the stock tank on one side to the other stock tank. A dispersion liquid in which all of the solvent is allowed to pass through the dispersion chamber for the same amount of time so that the solvent is not mixed with a different number of passes through the dispersion chamber while the solvent is passed in a one-way manner. An electrophotographic method is provided in which a photosensitive layer formed by coating and drying is provided on a conductive support.
[0023]
Seventeenth, an electrophotographic apparatus comprising at least a charging means, an image exposing means, a developing means, a transferring means, a cleaning means, a static eliminating means, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is a dispersion chamber At least one stock tank is connected to both ends of the pipe by a pipe, and a pump is arranged between the dispersion chamber and at least one stock tank. All of the solvent passes through the dispersion chamber for the same amount of time so that the solvent passes through the dispersion chamber and passes through the dispersion chamber in a one-way manner, so that solvents with different numbers of passages do not mix. An electrophotographic apparatus is provided in which a photosensitive layer formed by applying and drying a dispersion liquid dispersed in this manner is provided on a conductive support.
[0024]
Eighteenth, a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has at least one stock tank connected to both ends of a dispersion chamber by piping, In a device in which a pump capable of delivering a solvent is arranged between the dispersion chamber and at least one stock tank, the solvent is passed through the dispersion chamber from one stock tank to the other stock tank in a one-way manner. Is formed by applying and drying a dispersion liquid in which all the solvents pass through the dispersion chamber for the same period of time so that solvents having different numbers of passes through the dispersion chamber are not mixed. An electrophotographic process cartridge is provided in which the photosensitive layer is provided on a conductive support.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
First, a method for preparing the dispersion will be specifically described.
Any of the known organic pigments may be used as the organic pigment dispersed in the present invention. For example, phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, Examples thereof include quinone-based condensed polycyclic compounds, squaric acid-based dyes, naphthalocyanine-based pigments, and azulenium salt-based dyes.
[0026]
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 of CuKα ( 1.541 wavelength ) Titanyl phthalocyanine with a Bragg angle 2θ maximum diffraction peak at 27.2 ° ± 0.2 ° has an extremely high photocarrier generation ability, but its crystal form is unstable and can easily be converted to another crystal form. It will be converted. However, by using the present invention, a dispersion can be produced while maintaining the crystal form stably, and a dispersion can be obtained while maintaining the original photocarrier generation ability of the pigment.
[0027]
Moreover, when producing a dispersion liquid, using a binder resin in a solvent plays a very important role in terms of suppressing changes in crystal form. Any binder resin may be used depending on the application.
[0028]
Examples of the resin used in the electrophotographic photoreceptor dispersion include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, and poly-N-vinylcarbazole. , Polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like.
[0029]
FIG. 1 is a diagram showing an example of an apparatus suitable for producing the dispersion 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. Further, 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 53A and the liquid in the stock tank 53B as the liquid sent to the dispersion chamber 1.
[0030]
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.
[0031]
Using such a device, first put the liquid before dispersion into one side stock tank, send it to the dispersion chamber by a pump, and adjust it by valves 58 and 59 so that the dispersed liquid is 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 dispersion is started. Next, by adjusting the valves 58 and 59, dispersion is performed again so that the dispersion liquid is stored in the other stock tank from the stock tank containing the dispersion liquid that has passed once through the dispersion chamber.
Thereafter, by repeating this operation as necessary, a dispersion having a narrow particle size distribution, a small average particle size, and a small change in crystal form can be produced.
[0032]
Next, the electrophotographic photosensitive member produced according to the present invention will be described with reference to the drawings.
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. . FIGS. 3 and 4 are cross-sectional views showing another configuration example of the electrophotographic photosensitive member used in the present invention, in which 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.
[0033]
The conductive support 31 has a volume resistance of 10 ^Ten Films 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 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.
[0034]
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.
[0035]
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.
[0036]
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.
[0037]
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 be mentioned. 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.
[0038]
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.
[0039]
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. The charge generation layer 35 is formed by using a dispersion prepared using a dispersion apparatus as described above.
[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 electron 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., other bisstilbene derivatives, enamine derivatives, etc. Knowledge materials are mentioned. These charge transport materials may be used alone or in combination of two or more.
[0043]
Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene 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 Examples thereof include thermoplastic or thermosetting resins such as resins and 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 following general formulas (1) to (10) are preferably used, and these are exemplified below and specific examples are shown.
[0046]
(1) Polycarbonate represented by the general formula (1)
[Chemical 1]

Where R ₁ , R ₂ And 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 And R ₆ Represents a substituted or unsubstituted aryl group, respectively. o, p, and q each independently represent an integer of 0 to 4, k and j represent a composition, and 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9. n represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.
[Chemical 2]

Where R ₁₀₁ And R ₁₀₂ Each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m represent an integer 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]

(Wherein, a represents an integer of 1 to 20, b represents an integer of 1 to 2000, R ₁₀₃ And 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]
(2) Polycarbonate represented by the general formula (2)
[Formula 4]

Where R ₇ And R ₈ Represents a substituted or unsubstituted aryl group, Ar ₁ , Ar ₂ And Ar _Three Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (1).
[0048]
(3) Polycarbonate represented by the general formula (3)
[Chemical formula 5]

Where R ₉ And R _Ten Represents a substituted or unsubstituted aryl group, Ar _Four , Ar _Five And Ar ₆ Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (1).
[0049]
(4) Polycarbonate represented by the general formula (4)
[Chemical 6]

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

Where R ₁₃ And R ₁₄ Is a substituted or unsubstituted aryl group, Ar _Ten , Ar ₁₁ And Ar ₁₂ Each represents the same or different arylene group, X ₁ And 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 general formula (1).
[0051]
(6) Polycarbonate represented by the general formula (6)
[Chemical 8]

Where R ₁₅ , R ₁₆ , R ₁₇ And R ₁₈ Is a substituted or unsubstituted aryl group, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ And Ar ₁₆ Each represents the same or different arylene group, Y ₁ , Y ₂ And 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 or a sulfur atom, or a vinylene group, which may be the same or different. Also good. X, k, j, and n are the same as in the general formula (1).
[0052]
(7) Polycarbonate represented by the general formula (7)
[Chemical 9]

Where R ₁₉ And R ₂₀ Represents a hydrogen atom or a substituted or unsubstituted aryl group, R ₁₉ And R ₂₀ May form a ring. Ar ₁₇ , Ar ₁₈ And Ar ₁₉ Represent the same or different arylene groups. X, k, j, and n are the same as in the general formula (1).
[0053]
(8) Polycarbonate represented by the general formula (8)
Embedded image

Where R _{twenty one} Is a substituted or unsubstituted aryl group, Ar ₂₀ , Ar _{twenty one} , Ar _{twenty two} And Ar _{twenty three} Represents the same or different arylene groups, respectively. X, k, j, and n are the same as in the general formula (1).
[0054]
(9) Polycarbonate represented by the general formula (9)
Embedded image

Where R _{twenty two} , R _{twenty three} , R _{twenty four} And R _{twenty five} Is a substituted or unsubstituted aryl group, Ar _{twenty four} , Ar _{twenty five} , Ar ₂₆ , Ar ₂₇ And Ar ₂₈ Represents the same or different arylene groups, respectively. X, k, j, and n are the same as in the general formula (1).
[0055]
(10) Polycarbonate represented by the general formula (10)
Embedded image

Where R ₂₆ And R ₂₇ Is a substituted or unsubstituted aryl group, Ar ₂₉ , Ar ₃₀ And Ar ₃₁ Represents the same or different arylene groups, respectively. X, k, j, and n are the same as in the general formula (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. For the formation of the single-layer photosensitive layer, a dispersion liquid in which the pigment prepared by the specific method described above is dispersed in a binder resin can be used. That is, the single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance and a binder resin in a suitable solvent, and applying and drying them. 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 generating material is preferably 5 to 40 parts by weight with respect to 100 parts by weight of the binder resin, 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. A single-layer photosensitive layer is prepared 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 and a charge transport material if necessary. 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-described 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 in which inorganic materials such as titanium oxide, tin oxide, and potassium titanate are dispersed are used for the purpose of improving wear resistance. Can be added. As a method for forming the protective layer, a normal coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm. In addition 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.
[0062]
In the present invention, an intermediate layer can 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 provided with a photosensitive layer (preferably a TiOPc photosensitive layer giving a specific X-ray diffraction spectrum) formed on the conductive support using the dispersion prepared by the above-described method. Become. 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.
[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]
In addition, light sources such as the image exposure unit 5 and the charge removal lamp 2 emit 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 photoreceptor 21 has a photosensitive layer (preferably a TiOPc photosensitive layer that gives a specific X-ray diffraction spectrum) formed by using the dispersion prepared by the above-described method, and is driven by driving rollers 22a and 22b. Then, charging by the charger 23, image exposure by the light source 24, development (not shown), transfer using the charger 25, exposure before cleaning by the light source 26, cleaning by the brush 27, and static elimination by 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 exemplifies 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. The 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 (preferably a TiOPc photosensitive layer giving a specific X-ray diffraction spectrum) formed on the conductive support using the dispersion prepared by the above-described method. is there.
[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 phthalodinitrile and 4000 parts of 1-chloronaphthalene are stirred and mixed, 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, 1500 parts of 1,2-dichloroethane was added and stirred at room temperature for 2 hours, and 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]
The 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. A dispersion operation (referred to as path dispersion) in which liquid was fed from one stock tank to the other stock tank through a dispersion chamber was performed once.
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. 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 pass dispersion in Example 1 was performed twice. This is Dispersion Liquid 2.
[0081]
Example 3
A dispersion was prepared in exactly the same manner as in Example 1 except that the pass dispersion in Example 1 was performed 4 times. This is Dispersion Liquid 3.
[0082]
Comparative Example 1 The pass dispersion in Example 1 was not performed, and the circulation was dispersed (circulation dispersion time 30 minutes) using only the stock tank on one side by adjusting the valve from the beginning. This is Dispersion Liquid 4.
[0083]
Comparative Example 2 The path dispersion in Example 1 was not performed, and the valve was adjusted from the beginning to perform circulation dispersion (circulation dispersion time 180 minutes) using only one side stock tank. This is designated as Dispersion Liquid 5.
[0084]
Comparative Example 3 Under the dispersion conditions in Example 1, dispersion was performed without adding the butyral resin, and the butyral resin was dissolved after the dispersion. This is designated as Dispersion Liquid 6.
[0085]
The dispersions prepared as described above were evaluated as follows. The average particle size and particle size distribution were measured by HORIBA, Ltd .: CAPA700. In the evaluation of the particle size distribution, the range of each particle size with respect to the entire distribution was evaluated using numerical values calculated by the volume fraction. The dispersion was dried and powdered, and then the X-ray diffraction spectrum was measured. The results are shown in Table 1.
[0086]
[Table 1]

From Table 1, it can be seen that Dispersions 1 to 3 are fine dispersions having a fine average particle diameter and no change in crystal form.
[0087]
Subsequently, in order to evaluate coating property, the dispersion liquids 1-4 mentioned above were applied to the 30 mm diameter ariminium cylinder by the dip coating method. The state of the coating film was visually evaluated. The results are shown in Table 2.
[0088]
[Table 2]

Table 2 shows that when the dispersions 1 to 3 are used, a good coating film free from coating film defects can be obtained.
[0089]
As a preservation test, the dispersions 1 to 4 were stored at room temperature in a dark place for 1 month, and the state of the dispersion after storage was observed. The results are shown in Table 3.
[0090]
[Table 3]

From the results of Table 3, it can be seen that the dispersions 1 to 3 are excellent in storage stability and dispersion stability.
[0091]
Examples 4 to 6 and Comparative Examples 4 and 5
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.
[0092]
[Undercoat layer coating solution]
Titanium dioxide powder 15 parts
Polyvinyl butyral 6 parts
2-butanone 150 parts
[0093]
[Charge generation layer coating solution]
The dispersions 1 to 5 were used, respectively.
[0094]
[Charge transport layer coating solution]
10 parts of polycarbonate
7.5 parts of charge transport material of the following structural formula
Embedded image

80 parts of methylene chloride
[0095]
The electrophotographic photoreceptor thus obtained was mounted on the electrophotographic process shown in FIG. 6 (however, no exposure before cleaning), and the image exposure light source was a 780 mm semiconductor laser (image writing by a polygon mirror). . 8000 sheets were printed continuously, and image evaluation at that time was performed. The results are shown in Table 4.
[0096]
[Table 4]

In the charge generation layer of the photoreceptor using the dispersion 4, coarse particles were present in the dispersion, and thus a coating film defect (poach, streak, etc.) was generated. As a result, the occurrence of abnormal images was observed. Further, the photoreceptor using the dispersion 5 caused a decrease in image density after repeated use. It can be seen from Table 4 that the photoreceptors using the dispersions 1 to 3 give good images even at the initial stage and after repeated use.
[0097]
Examples 7 and 8 and Comparative Example 6
After anodizing the surface of the aluminum cylinder, sealing treatment was performed. 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.
[0098]
[Charge generation layer coating solution]
The dispersion 1 was used in Example 7, the dispersion 2 was used in Example 8, and the dispersion 5 was used in Comparative Example 6.
[0099]
[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
[0100]
The electrophotographic photoreceptor thus obtained 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 photoreceptor immediately before development could be measured. Table 5 shows the results obtained by continuously printing 6000 sheets and measuring the surface potential of the image exposed part and the image non-exposed part at that time at the initial stage and after 6000 sheets.
[0101]
[Table 5]

From Table 5, it can be seen that the photoreceptor using the dispersions 1 and 2 maintains a stable surface potential even after repeated use.
[0102]
Example 9
A photoconductor was prepared in exactly the same manner as in Example 4 except that the support in Example 4 was changed from an electroformed nickel belt to an aluminum cylinder.
[0103]
Example 10
A photoconductor was prepared in the same manner as in Example 4 except that the charge transport layer coating solution of Example 4 was changed to the following composition.
[0104]
[Charge transport layer coating solution]
10 parts of polymer charge transport material of the following structural formula
Embedded image

100 parts methylene chloride
[0105]
Example 11
A photoconductor was prepared in the same manner as in Example 4 except that the charge transport layer coating solution of Example 4 was changed to the following composition.
[0106]
[Charge transport layer coating solution]
10 parts of polymer charge transport material of the following structural formula
Embedded image

100 parts methylene chloride
[0107]
Each of the electrophotographic photoreceptors of Examples 9 to 11 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 6.
[0108]
[Table 6]

From Table 4, it can be seen that the electrophotographic photoreceptors of Examples 10 and 11 exhibit particularly wear resistance.
[0109]
【The invention's effect】
According to the present invention, there is provided a method for producing a dispersion that is very efficient in producing a dispersion and that does not change the crystal form. By using this method, particles can be maintained while maintaining a specific crystal form. A fine diameter dispersion is provided. 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 view 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 representative electrophotographic apparatus of the present invention.
FIG. 8 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment obtained by the pigment production example of the present invention.
[Explanation of symbols]
1 Photoconductor
2 Static elimination lamp
3 Charger charger
4 Eraser
5 Image exposure section
6 Development unit
7 Charger before transfer
8 Registration roller
9 Transfer paper
10 Transcription charger
11 Separate charger
12 Separating nails
13 Charger before cleaning
14 Fur brush
15 Cleaning blade
16 photoconductor
17 Charger charger
18 Cleaning brush
19 Image exposure section
20 Developing roller
21 photoconductor
22a, 22b Driving roller
23 Charger charger
24 Image exposure source
25 Transcription Charger
26 Exposure section before cleaning
27 Cleaning brush
28 Static elimination light source
31 Conductive support
33 Photosensitive layer
35 Charge generation layer
37 Charge transport layer
51 Dispersion chamber
52 motor
53A, 53B Stock tank
54A, 54B Stirrer
55 pump
58 Three-way valve
59 Three-way valve

Claims (3)

A solvent containing titanyl phthalocyanine having a Bragg angle 2θ maximum diffraction peak of 27.2 ± 0.2 ° with respect to the characteristic X-ray of CuKα (wavelength 1.541 mm) passes through the dispersion chamber containing the dispersion medium. In the method for producing a dispersion for dispersing the titanyl phthalocyanine,
At least two or more stock tanks are connected to both ends of the dispersion chamber by piping, and a stock on one side is provided in an apparatus in which a pump capable of feeding a solvent is disposed between the dispersion chamber and at least one stock tank. By passing the solvent through the dispersion chamber from the tank to the other stock tank and passing in one way, all of the solvent passes through the dispersion chamber for the same time and dispersion is performed. A method for producing a dispersion. The method for producing a dispersion according to claim 1 , wherein a resin is used in the solvent. A dispersion for an electrophotographic photosensitive member produced by the method according to claim 1 .

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