JP3604745B2 - Electrophotographic photoreceptor, electrophotographic apparatus using the electrophotographic photoreceptor, and electrophotographic apparatus unit - Google Patents

Description

【００１２】
また、本発明の電子写真装置は、上記電子写真感光体と、前記電子写真感光体を帯電させる帯電手段と、帯電した前記電子写真感光体に対し像露光を行い静電潜像を形成する像露光手段と、静電潜像の形成された前記電子写真感光体をトナーで現像する現像手段とを有するものである。
【００１３】
更に、本発明の電子写真装置ユニットは、上記電子写真感光体と、前記電子写真感光体に接触して前記電子写真感光体を帯電させる直接帯電部材とを有するものである。
【００１４】
上記のビスアゾ顔料を感光層、電荷発生層に含有することにより、ＴｉＯＰｃの高感度特性を損なうことなく、繰り返し使用時の電位安定性や高温高湿下における黒ポチの発生を改善することができる。上記のビスアゾ顔料には８００ｎｍ付近に感度が全く無いにも拘らず、化学的増感作用によりＴｉＯＰｃの有する８００ｎｍ付近の感度が増感されるため、ＴｉＯＰｃの量を減らしても高感度特性を維持できる。
【００１５】
本発明の参考例で使用するビスアゾ顔料を以下に示す。
【００１６】
【外５】

【００１７】
本発明で使用するビスアゾ顔料を以下に示す。
【化２】

【００１８】
本発明で用いるビスアゾ顔料は、相当するジアミンを常法によりテトラゾ化し、アルカリの存在下カプラーと水系でカップリングするか、または前記ジアミンのテトラゾニウム塩をホウフッ化塩あるいは塩化亜鉛複塩等の形で一旦単離した後、適当な溶剤、例えばＮ，Ｎ−ジメチルホルムアミド、ジメチルスルホキシド等の溶剤中で酢酸ソーダ、トリエチルアミン、Ｎ−メチルモルホリン等の塩基の存在下、前記カプラーとカップリングすることにより容易に合成できる。
【００１９】
本発明において用いるＴｉＯＰｃは次の構造式を有する。
【００２０】
【外７】

【００２１】
（ただし、Ｙ_１、Ｙ_２、Ｙ_３及びＹ_４はＣｌまたはＢｒを表し、ｎ、ｍ、ｋ及びｐは０〜４の整数である。）
ＴｉＯＰｃの結晶形は、いかなるものでもよいが、α型、β型、Ｉ型またはＹ型が好ましい。特にＩ型結晶が好ましい。
【００２２】
Ｉ型結晶のＴｉＯＰｃは、ＣｕＫα特性Ｘ線回折において、少なくともブラッグ角（２θ±０．２°）９．０°、１４．２°、２３．９°及び２７．１°のピークを有する。Ｉ型結晶ＴｉＯＰｃのＸ線回折図の好ましい例を図１に示した。
【００２３】
α型結晶のＴｉＯＰｃは、少なくともブラッグ角（２θ±０．２°）７．６°及び２８．６°にピークを有する。α型結晶ＴｉＯＰｃのＸ線回折図の好ましい例を図２に示した。
【００２４】
β型結晶のＴｉＯＰｃは、少なくともブラッグ角（２θ±０．２°）９．３°及び２６．３°にピークを有する。β型結晶ＴｉＯＰｃのＸ線回折図の好ましい例を図３に示した。
【００２５】
Ｙ型結晶のＴｉＯＰｃは、少なくともブラッグ角（２θ±０．２°）９．５°及び２７．３°にピークを有する。Ｙ型結晶ＴｉＯＰｃのＸ線回折図の好ましい例を図４に示した。
【００２６】
本発明においてＸ線回折の測定は、ＣｕＫα線を用いて次の条件により行ったものである。
使用測定機：理学電器製Ｘ線回折装置
ＲＡＤ−Ａシステム
Ｘ線管球：Ｃｕ
管電圧：５０ｋＶ
管電流：４０ｍＡ
スキャン方法：２θ／θスキャン
スキャン速度：２ｄｅｇ．／ｍｉｎ
サンプリング間隔：０．０２０ｄｅｇ．
スタート角度（２θ）：３ｄｅｇ．
ストップ角度（２θ）：４０ｄｅｇ．
ダイバージェンススリット：０．５ｄｅｇ．
スキャッタリングスリット：０．５ｄｅｇ．
レシービングスリット：０．３ｍｍ
湾曲モノクロメーター使用
感光層は単一層でもかまわないが、図５に示すように支持体３側から順に電荷発生層２及び電荷輸送層１を積層して構成するのが好ましい。また、図８に示すように支持体３側から順に電荷輸送層１及び電荷発生層２を積層してもよい。更に、図６、図７、図９及び図１０に示すように、電荷発生層２をビスアゾ顔料を含む第１電荷発生層２ａと、ＴｉＯＰｃを含む第２電荷発生層２８とに分けて、これらを積層する構成にしてもよい。この場合、図６及び図９に示すようにビスアゾ顔料を含む第１電荷発生層２ａが電荷輸送層１と接するようにしてもよいし、図７及び図１０に示すようにＴｉＯＰｃを含む第２電荷発生層２ｂが電荷輸送層１と接するようにしてもよいが、第２電荷発生層２ｂを電荷輸送層１に接触させる方が好ましい結果が得られる。第１電荷発生層と第２電荷発生層との境界は明確でなくてもかまわない。
【００２７】
感光層が単一層の場合、感光層はＴｉＯＰｃあるいはビスアゾ顔料と、電荷輸送材料と、結着樹脂とを、溶媒で混合して通常のコーティング法により成膜して形成する。
【００２８】
感光層が、電荷発生層及び電荷輸送層で構成される場合、電荷発生層はＴｉＯＰｃあるいはビスアゾ顔料、またはこれら両方と結着樹脂とを、溶媒で混合して通常のコーティング法により成膜して形成する。
【００２９】
電荷輸送材料としては例えば各種のトリアリールアミン系化合物、ヒドラゾ系化合物、スチルベン系化合物、ピラゾリン系化合物、オキサゾール系化合物、チアゾール系化合物、トリアリルメタン系化合物等が挙げられる。
【００３０】
各層に用いる結着樹脂としては、例えばポリエステル、アクリル樹脂、ポリビニルカルバゾール、フェノキシ樹脂、ポリカーボネート、ポリビニルブチラール、ポリビニルベンザール、ポリスチレン、ポリビニルアセテート、ポリスルホン、ポリアレート、塩化ビニリデン、アクリロニトリル共重合体等が挙げられる。
【００３１】
各層を塗工するコーティング法としては、一般的なものが使用でき、例えば浸漬コーティング法、スプレーコーティング法、スピンナーコーティング法、ローラーコーティング法、マイヤーバーコーティング法、ブレードコーティング法などのコーティング法が使用できる。
【００３２】
感光層が単一層の場合、ＴｉＯＰｃとビスアゾ顔料とを合わせた含有率は、感光層に対して３〜３０重量％が好ましい。ＴｉＯＰｃとビスアゾ顔料の混合比は、ＴｉＯＰｃ／ビスアゾ顔料で表現して２０／１〜３／７、更には１５／１〜４／６が好ましく、特にＴｉＯＰｃをビスアゾ顔料よりも多くするのが好ましい。電荷輸送材料の含有率は感光層に対して３０〜７０重量％が好ましい。
【００３３】
感光層を、電荷発生層及び電荷輸送層で構成する場合の各成分の含有率は以下の通りである。
【００３４】
ＴｉＯＰｃとビスアゾ顔料とを混合して同一層に含める場合、ＴｉＯＰｃとビスアゾ顔料とを合わせた含有率は、電荷発生層に対して２０〜８０重量％、更には３０〜７０重量％が好ましい。この場合、ＴｉＯＰｃとビスアゾ顔料の混合比は、感光層が単一層の場合と同様である。
【００３５】
ビスアゾ顔料とＴｉＯＰｃとを、それぞれ第１電荷発生層と第２電荷発生層に別々に含有する場合、ビスアゾ顔料とＴｉＯＰｃの含有量は、いずれもそれぞれの含有する電荷発生層に対して２０〜８０重量％、更には３０〜７０重量％が好ましい。
【００３６】
電荷輸送材料の含有率は、電荷輸送層に対して３０〜７０重量％が好ましい。
【００３７】
感光層が単一層の場合、感光層の厚みは５〜５０μｍ、更には１０〜４０μｍが好ましい。
【００３８】
ビスアゾ顔料及びＴｉＯＰｃの両方を一緒に含有する電荷発生層の厚みは、０．０５〜１．０μｍ、更には０．１〜０．５μｍが好ましい。ビスアゾ顔料を含有する第１電荷発生層の厚みは０．０５〜０．２μｍが好ましく、第２電荷発生層の厚みは０．０５〜１．０μｍ、更には０．１〜０．５μｍが好ましい。
【００３９】
電荷輸送層の厚みは、５〜５０μｍ、更には８〜２０μｍが好ましい。
【００４０】
支持体は、例えばアルミニウム、アルミニウム合金、ステンレス等の導電性材料を用いて形成できる。また、プラスチック、紙あるいは金属などの支持体表面に導電表面層を形成したものも使用することができる。導電表面層としては、アルミニウム、アルミニウム合金、酸化インジウム−酸化錫合金等の真空蒸着膜や、バインダーに導電性粒子（例えばカーボンブラック、酸化錫粒子等）を混入して塗工した塗工膜を用いることができる。導電表面層の厚さは、１〜３０μｍが好ましい。支持体の形状は、例えば円筒状、フィルム状が好ましい。
【００４１】
支持体あるいは導電表面層と、感光層との間に、バリヤー機能や接着機能を有する下引層を必要に応じ設けてもよい。下引層は例えばカゼイン、ポリビニルアルコール、ニトロセルロース、エチレン−アクリル酸コポリマー、ポリアミド、変性ポリアミド、ポリウレタン、ゼラチン、酸化アルミニウム等によって形成できる。下引層の膜厚は５μｍ以下、更には０．５〜３μｍが好ましい。下引層は１０^７ Ω・ｃｍ以上であることが望ましい。
【００４２】
更に支持体と下引層との間に、支持体の欠陥の被服層及び画像入力がレーザー光の場合には散乱による干渉縞防止を目的とした導電層を必要に応じ設けることが好適である。導電層はカーボンブラック、金属粒子、金属酸化物等の導電性粉体を結着樹脂中に分散、塗布することで形成できる。導電層の膜厚は５〜４０μｍ、好ましくは１０〜３０μｍである。
【００４３】
感光層上には、必要に応じて保護層を設けてもよい。保護層は、ポリビニルブチラール、ポリエステル、ポリカーボネート（ポリカーボネートＺ、変性ポリカーボネート等）、ナイロン、ポリイミド、ポリアリレート、ポリウレタン、スチレン−ブタジエンコポリマー、スチレン−アクリル酸コポリマー、スチレン−アクリロニトリルコポリマー等の樹脂を適当な有機溶剤によって溶解し、感光層の上に塗布、乾燥して形成できる。保護層の膜厚は、０．０５〜２０μｍが好ましい。また、保護層中に導電性粒子や紫外線吸収剤等を含ませてもよい。導電性粒子としては、例えば酸化錫粒子等の金属酸化物が好ましい。
【００４４】
次に、本発明の電子写真感光体を用いた電子写真装置について説明する。
【００４５】
図１１において、１１は本発明のドラム型感光体であり軸１１ａを中心に矢印方向に所定の周速度で回転駆動する。該感光体１１はその回転過程で帯電手段１２により周面に正または負の所定電位の均一帯電を受け、次いで露光部１３にて不図示の像露光手段により光像露光Ｌ（スリット露光あるいはレーザービーム走査露光等）を受ける。これにより感光体周面に露光像に対応した静電潜像が順次形成されていく。その静電潜像は、次いで現像手段４でトナー現像され、そのトナー現像像がコロナ転写手段５により不図示の給紙部から感光体１１と転写手段５との間に感光体１１の回転と同期取りされて給送された記録材９の面に順次転写されていく。像転写を受けた記録材９は感光体面から分離されて像定着手段８へ導入されて像定着を受けて複写物（コピー）として機外へプリントアウトされる。像転写後の感光体１１の表面はクリーニング手段６にて転写残りトナーの除去を受けて清浄面化され、前露光手段７により除電処理がされて繰り返して像形成に使用される。感光体１１の均一帯電手段１２としてはコロナ帯電装置が一般に広く使用されている。
【００４６】
また、図１２及び図１３に示すように、帯電手段として直接帯電部材１０を用い、電圧印加された直接帯電部材１０を感光体１１に接触させることにより感光体１１の帯電を行ってもよい（この帯電方法を、以下直接帯電という）。図１２及び図１３に示す装置では感光体１１上のトナー像も、直接帯電部材２３で記録材９に転写される。即ち、電圧印加された直接帯電部材２３を記録材９に接触させることにより感光体１１上のトナー像を記録材９に転写させる。
【００４７】
また、図１２に示す装置では、少なくとも感光体１１、直接帯電部材１０及び現像手段４を容器２０に納めてひとつの電子写真装置ユニットとし、この装置ユニットを装置本体のレール等の案内手段を用いて着脱自在に構成している。クリーニング手段６は容器２０内に配置しても配置しなくてもよい。
【００４８】
更に、図１３に示す装置では、少なくとも感光体１１及び直接帯電部材１０を第１の容器２１に納めて、第１の電子写真装置ユニットとし、少なくとも現像手段７を第２の容器２２に納めて第２の電子写真装置ユニットとし、これら第１の装置ユニットと、第２の装置ユニットとを着脱自在に構成している。クリーニング手段６は容器２１内に配置しても配置しなくてもよい。
【００４９】
光像露光Ｌは、電子写真装置を複写機やプリンターとして使用する場合には、原稿からの反射光や透過光を用いる、あるいは、原稿を読み取り信号化に従って、この信号によりレーザービームの走査、発光ダイオードアレイの駆動、または液晶シャッターアレイの駆動などを行うことにより行われる。
【００５０】
本発明の電子写真感光体は、レーザービームプリンター、電子写真複写機、ＣＲＴプリンター、ＬＥＤプリンター、液晶プリンター、レーザー製版等の電子写真応用分野に広く用いることができる。
【００５１】
以上説明した本発明の電子写真感光体は、ＴｉＯＰｃの有する高感度特性を損なうことなく、繰り返し使用しても電位安定性に優れると共に高温高湿下における黒ポチの発生を防止することができる。
【００５２】
【実施例】
以下に示す「部」は、「重量部」を意味する。
【００５３】
参考例１
１０％酸化アンチモンを含有する酸化スズで被覆した酸化チタン粉体５０部、レゾール型フェノール樹脂２５部、メチルセロソルブ２０部、メタノール５部及びシリコーンオイル（ポリジメチルシロキサンポリオキシアルキレン共重合体、平均分子量３０００）０．００２部を１ｍｍφガラスビーズを用いたサンドミル装置で２時間分散して導電層用塗料を調製し、この塗料をアルミニウムシリンダー（外径８０ｍｍ、長さ３６０ｍｍ）の外周に浸漬塗布し、１４０℃で３０分間乾燥させ、膜厚２０μｍの導電層を形成した。
【００５４】
この導電層の上に６−６６−６１０−１２四元素系ポリアミド共重合体（アミランＣＭ８０００、東レ製）５部をメタノール７０部とブタノール２５部の混合溶媒に溶解した溶液を浸漬塗布し、乾燥して膜厚１μｍの下引層を形成した。
【００５５】
Ｉ型ＴｉＯＰｃ６部と前記した顔料例１のビスアゾ顔料４部をポリビニルブチラール（商品名エスレックＢＸ−１、積水化学製）１０部をシクロヘキサノン４００部に溶解した液に添加し、１ｍｍφのガラスビーズを用いたサンドミルで３時間分散し、これに４００部の酢酸エチルを加えて、希釈した後回収して、これを下引層上に浸漬塗布し、８０℃で１０分間乾燥して膜厚０．２５μｍの電荷発生層を形成した。
【００５６】
下記構造式の電荷輸送材料１０部と、
【外８】

【００５７】
ビスフェノールＺ型ポリカーボネート１０部をクロロベンゼン６０部に溶解した溶液を調製し、この溶液を電荷発生層上に浸漬塗布し、１１０℃で１時間乾燥し、膜厚２０μｍの電荷輸送層を形成し、本発明の参考例１に係る電子写真感光体を作成した。
【００５８】
参考例１で作成した電子写真感光体をレーザービームプリンター（商品名ＬＢＰ−ＳＸ、キヤノン（株）製）に装着して、暗部電位を−７００Ｖとし、これに８０２ｎｍのレーザー光を照射して明部電位が−１５０Ｖとなるレーザー光量を測定することにより感度を比較した。また５０００枚連続コピーを行った時の暗部電位の変化量（ΔＶ_Ｄ）と明部電位の変化量（ΔＶ_Ｌ）を測定した。更に温度３５℃、湿度９０％の高温高湿環境下で、全面白画像を出力し黒ポチの発生程度を評価した。
【００５９】
結果を表１に示す。なお、表中の黒ポチ欄の評価は、黒ポチの発生程度を６段階で表した基準サンプルと比較して評価したもので、０は黒ポチなしを表し、５は画像領域全域に黒ポチが発生して画像領域全域がグレーにみえる状態を表している。従って、０から５まで数値が大きくなるに従って黒ポチの発生頻度が高くなる。黒ポチ評価は０〜２が実用に供せるものである。
【００６０】
【表１】

参考例２
参考例１のＩ型ＴｉＯＰｃ６部及び顔料例１のビスアゾ顔料４部の代わりに、Ｉ型ＴｉＯＰｃ１０部を含有してその他は参考例１と同様にしてＩ型ＴｉＯＰｃ分散液を調整した。また、前記した顔料例１のビスアゾ顔料１０部を、参考例１のＩ型ＴｉＯＰｃ６部及び顔料例１のビスアゾ顔料４部の代わりに用いて、その他は参考例１と同様にしてビスアゾ顔料分散液を調整した。
【００６１】
参考例１と同様にして作成した導電層及び下引層の上に上記のビスアゾ顔料分散液を膜厚０．１μｍになるように塗工し、更にこの上に上記のＴｉＯＰｃ分散液を膜厚０．２５μｍになるようにスプレー塗工して電荷発生層を形成した。電荷輸送層は参考例１と全く同様にして形成し、本発明の参考例２に係る電子写真感光体を作成した。
【００６２】
参考例３
参考例２におけるビスアゾ顔料分散液とＴｉＯＰｃ分散液の塗工の順序を逆とした他は、参考例２と全く同様にして電子写真感光体を作成した。
【００６３】
参考例２及び３で作成した電子写真感光体について、参考例１の電子写真感光体の場合と同様に評価を行った。結果を表２に示す。
【００６４】
【表２】

【００６５】
この結果から分かるように、本発明の参考例における特定のビスアゾ顔料を積層した電子写真感光体においては、繰り返し特性や黒ポチ発生が改善されるが、ビスアゾ顔料を含む電荷発生層を導電性支持体側に設けた方がより好ましい。
【００６６】
実施例１
参考例１と全く同様にして、アルミニウムシリンダー上に導電層、下引層を形成した。
【００６７】
次に、参考例１において用いた顔料例１のビスアゾ顔料に代えて前記した顔料例２のビスアゾ顔料を用い、その他は、参考例１と全く同様にして電荷発生層、電荷輸送層を形成して本発明の電子写真感光体を作成した。
【００６８】
実施例１の電子写真感光体を、直接帯電方式に改良したキヤノン社製レーザービームプリンターＬＢＰ−ＳＸに装着し、参考例１と同様にして評価した。レーザービームプリンターの直接帯電部材には−７２０Ｖの直流電圧とピーク間電圧１５００Ｖの交流電圧を重畳して印加し、電子写真感光体の暗部電位を−７００Ｖとした。評価結果を表３に示した。
【００６９】
【表３】

この結果から分かるように、本発明における特定のビスアゾ顔料を積層した電子写真感光体においては、繰り返し特性や黒ポチ発生が改善される。
【００７０】
【発明の効果】
本発明はＴｉＯＰｃを電荷発生層に用いた電子写真感光体において、繰り返し特性や高温高湿下における画像欠陥が改善され、高感度で高品位な画像が得られるという顕著な効果を奏する。
【図面の簡単な説明】
【図１】Ｉ型オキシチタニウムフタロシアニンのＸ線回折図である。
【図２】α型オキシチタニウムフタロシアニンのＸ線回折図である。
【図３】β型オキシチタニウムフタロシアニンのＸ線回折図である。
【図４】Ｙ型オキシチタニウムフタロシアニンのＸ線回折図である。
【図５】本発明の電子写真感光体の層構成の例である。
【図６】本発明の電子写真感光体の層構成の他の例である。
【図７】本発明の電子写真感光体の層構成の他の例である。
【図８】本発明の電子写真感光体の層構成の他の例である。
【図９】本発明の電子写真感光体の層構成の他の例である。
【図１０】本発明の電子写真感光体の層構成の他の例である。
【図１１】本発明の電子写真装置の一例を示す図である。
【図１２】本発明の電子写真装置の他の例を示す図である。
【図１３】本発明の電子写真装置の他の例を示す図である。
【符号の説明】
１ 電荷輸送層
２ 電荷輸送層
３ 支持体
４ 現像手段
５ 転写手段
６ クリーニング手段
７ 前露光手段
８ 定着手段
９ 記録材
１０、２３ 直接帯電部材
１１ 感光体
１２ 帯電手段
１３ 露光部[0001]
[Industrial applications]
The present invention relates to an electrophotographic photosensitive member, an electrophotographic device including the electrophotographic photosensitive member, and an electrophotographic unit.
[0002]
[Prior art]
Electrophotographic photoreceptors using organic photoconductors have remarkable improvements in sensitivity and durability due to the development of a function-separated photoreceptor in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated. And have come to be widely used in practice.
[0003]
In particular, in recent years, non-impact printers to which electrophotographic technology is applied have been widely used in place of conventional impact-type printers as terminal printers. These are mainly laser beam printers using laser light as a light source, and a semiconductor laser is used as the light source in terms of cost, size of the apparatus, and the like. Currently, mainly used semiconductor lasers have an oscillation wavelength of 780 ± 20 nm, which is a long wavelength. Therefore, development of an electrophotographic photoreceptor having sufficient sensitivity to such long-wavelength light has been promoted.
[0004]
As a charge generation material having sensitivity to such long-wavelength light, phthalocyanine compounds such as metal-free phthalocyanine, copper phthalocyanine, and oxytitanium phthalocyanine (hereinafter abbreviated as TiOPc) have been found to have high sensitivity characteristics and have been practically used. It has led to. In particular, TiOPc has extremely high sensitivity characteristics, and, like other phthalocyanine compounds, has various crystal forms, and the electrophotographic characteristics are different due to the difference of these crystal forms, and therefore, intensive research has been made.
[0005]
Representative crystal forms of TiOPc having excellent sensitivity characteristics to long-wavelength light include JP-A-61-239248, JP-A-62-67094, JP-A-3-129973, and JP-A-3-128973. -200790 and the like. The crystal forms are referred to as α-type, β-type, I-type, and Y-type in this order, as described later.
[0006]
[Problems to be solved by the invention]
However, the conventional electrophotographic photoreceptor using TiOPc is not always satisfactory with respect to the potential stability at the time of repeated use. Further, in a reversal developing electrophotographic process, black spots (black on a white background) are obtained under high temperature and high humidity. (A phenomenon that dot-like fogging occurs) is liable to occur. As a countermeasure to remedy such a defect, there are a method of reducing the thickness of the charge generation layer and an increase of the ratio of the binder resin in the ratio of TiOPc to the binder resin in the charge generation layer. It wasn't a complete solution, as it would reduce sensitivity.
[0007]
Japanese Patent Application Laid-Open No. 3-37656 discloses a technique of mixing or laminating a bisazo pigment with TiOPc for the purpose of obtaining a panchromatic photoreceptor capable of coping with an apparatus having both functions of a laser beam printer and a copying machine. However, these bisazo pigments have almost no effect of improving the above-mentioned disadvantages.
[0008]
The present invention provides an electrophotographic photoreceptor having stable electrical characteristics even when repeatedly used with high sensitivity, and having no black spots even when used under high temperature and high humidity, an electrophotographic apparatus using the electrophotographic photoreceptor, and An object of the present invention is to provide an electrophotographic apparatus unit.
[0009]
[Means for Solving the Problems]
That is, the present invention provides an electrophotographic photosensitive member having at least a photosensitive layer on a support, wherein the photosensitive layer contains oxytitanium phthalocyanine and a bisazo pigment represented by the following general formula (II). Electrophotographic photoreceptor.
[0011]
[ Outside 4 ]

[0012]
Further, the electrophotographic apparatus of the present invention includes the electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and an image for forming an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member. An exposure unit; and a developing unit for developing the electrophotographic photosensitive member, on which the electrostatic latent image is formed, with toner.
[0013]
Further, an electrophotographic apparatus unit according to the present invention includes the electrophotographic photosensitive member and a direct charging member that contacts the electrophotographic photosensitive member and charges the electrophotographic photosensitive member.
[0014]
By including the bisazo pigment in the photosensitive layer and the charge generation layer, the potential stability during repeated use and the occurrence of black spots under high temperature and high humidity can be improved without impairing the high sensitivity characteristics of TiOPc. . Although the above bisazo pigment has no sensitivity at around 800 nm, the sensitivity at around 800 nm of TiOPc is sensitized by the chemical sensitizing effect, so that high sensitivity characteristics are maintained even when the amount of TiOPc is reduced. it can.
[0015]
The bisazo pigments used in Reference Examples of the present invention are shown below.
[0016]
[ Outside 5 ]

[0017]
The bisazo pigment used in the present invention is shown below.
Embedded image

[0018]
The bisazo pigment used in the present invention is a tetrazotization of the corresponding diamine by a conventional method, and coupling with a coupler and an aqueous system in the presence of an alkali, or a tetrazonium salt of the diamine in the form of a borofluoride salt or a zinc chloride double salt. Once isolated, it is easily coupled with the coupler in the presence of a base such as sodium acetate, triethylamine or N-methylmorpholine in a suitable solvent such as N, N-dimethylformamide or dimethylsulfoxide. Can be synthesized.
[0019]
TiOPc used in the present invention has the following structural formula.
[0020]
[ Outside 7 ]

[0021]
(However, Y ₁ , Y ₂ , Y ₃ and Y ₄ represent Cl or Br, and n, m, k and p are integers of 0 to _4. )
The crystal form of TiOPc may be any, but α-type, β-type, I-type or Y-type is preferred. Particularly, an I-type crystal is preferable.
[0022]
TiOPc of the I-type crystal has peaks of at least Bragg angles (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 °, and 27.1 ° in CuKα characteristic X-ray diffraction. FIG. 1 shows a preferred example of the X-ray diffraction pattern of the I-type crystal TiOPc.
[0023]
TiOPc of the α-type crystal has peaks at least at Bragg angles (2θ ± 0.2 °) of 7.6 ° and 28.6 °. FIG. 2 shows a preferred example of the X-ray diffraction pattern of the α-type crystal TiOPc.
[0024]
The β-type crystal TiOPc has peaks at least at Bragg angles (2θ ± 0.2 °) of 9.3 ° and 26.3 °. FIG. 3 shows a preferred example of the X-ray diffraction pattern of the β-type crystal TiOPc.
[0025]
TiOPc of the Y-type crystal has peaks at least at Bragg angles (2θ ± 0.2 °) of 9.5 ° and 27.3 °. FIG. 4 shows a preferred example of the X-ray diffraction pattern of the Y-type crystal TiOPc.
[0026]
In the present invention, the measurement of X-ray diffraction is performed using CuKα radiation under the following conditions.
Measuring machine used: Rigaku Denki's X-ray diffractometer RAD-A system X-ray tube: Cu
Tube voltage: 50 kV
Tube current: 40 mA
Scan method: 2θ / θ scan Scan speed: 2 deg. / Min
Sampling interval: 0.020 deg.
Start angle (2θ): 3 deg.
Stop angle (2θ): 40 deg.
Divergence slit: 0.5 deg.
Scattering slit: 0.5 deg.
Receiving slit: 0.3mm
The photosensitive layer using the curved monochromator may be a single layer, but is preferably formed by laminating the charge generation layer 2 and the charge transport layer 1 sequentially from the support 3 side as shown in FIG. In addition, as shown in FIG. 8, the charge transport layer 1 and the charge generation layer 2 may be sequentially stacked from the support 3 side. Further, as shown in FIGS. 6, 7, 9 and 10, the charge generation layer 2 is divided into a first charge generation layer 2a containing a bisazo pigment and a second charge generation layer 28 containing TiOPc. May be laminated. In this case, the first charge generation layer 2a containing the bisazo pigment may be in contact with the charge transport layer 1 as shown in FIGS. 6 and 9, or the second charge generation layer 2 containing TiOPc as shown in FIGS. Although the charge generation layer 2b may be in contact with the charge transport layer 1, it is more preferable to bring the second charge generation layer 2b into contact with the charge transport layer 1. The boundary between the first charge generation layer and the second charge generation layer may not be clear.
[0027]
When the photosensitive layer is a single layer, the photosensitive layer is formed by mixing TiOPc or a bisazo pigment, a charge transport material, and a binder resin with a solvent and forming a film by an ordinary coating method.
[0028]
When the photosensitive layer is composed of a charge generation layer and a charge transport layer, the charge generation layer is formed by mixing TiOPc or bisazo pigment, or both, and a binder resin with a solvent, and forming a film by a normal coating method. Form.
[0029]
Examples of the charge transport material include various triarylamine compounds, hydrazo compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triallylmethane compounds, and the like.
[0030]
Examples of the binder resin used for each layer include polyester, acrylic resin, polyvinyl carbazole, phenoxy resin, polycarbonate, polyvinyl butyral, polyvinyl benzal, polystyrene, polyvinyl acetate, polysulfone, polyalate, vinylidene chloride, and acrylonitrile copolymer. .
[0031]
As a coating method for coating each layer, a general method can be used, and for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, and a blade coating method can be used. .
[0032]
When the photosensitive layer is a single layer, the total content of TiOPc and bisazo pigment is preferably 3 to 30% by weight based on the photosensitive layer. The mixing ratio of TiOPc to bisazo pigment is preferably 20/1 to 3/7, more preferably 15/1 to 4/6, expressed as TiOPc / bisazo pigment, and particularly preferably, TiOPc is larger than bisazo pigment. The content of the charge transporting material is preferably from 30 to 70% by weight based on the photosensitive layer.
[0033]
When the photosensitive layer is composed of the charge generation layer and the charge transport layer, the content of each component is as follows.
[0034]
When TiOPc and bisazo pigment are mixed and included in the same layer, the combined content of TiOPc and bisazo pigment is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the charge generation layer. In this case, the mixing ratio between TiOPc and the bisazo pigment is the same as in the case where the photosensitive layer is a single layer.
[0035]
When the bisazo pigment and TiOPc are separately contained in the first charge generation layer and the second charge generation layer, respectively, the content of the bisazo pigment and TiOPc is 20 to 80 with respect to the respective charge generation layers. % By weight, more preferably 30 to 70% by weight.
[0036]
The content of the charge transport material is preferably from 30 to 70% by weight based on the charge transport layer.
[0037]
When the photosensitive layer is a single layer, the thickness of the photosensitive layer is preferably 5 to 50 μm, more preferably 10 to 40 μm.
[0038]
The thickness of the charge generation layer containing both the bisazo pigment and TiOPc is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.5 μm. The thickness of the first charge generation layer containing the bisazo pigment is preferably from 0.05 to 0.2 μm, and the thickness of the second charge generation layer is preferably from 0.05 to 1.0 μm, more preferably from 0.1 to 0.5 μm. .
[0039]
The thickness of the charge transport layer is preferably 5 to 50 μm, more preferably 8 to 20 μm.
[0040]
The support can be formed using a conductive material such as aluminum, an aluminum alloy, and stainless steel. Further, a support having a conductive surface layer formed on the surface of a support such as plastic, paper or metal can also be used. As the conductive surface layer, a vacuum deposited film of aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like, or a coating film formed by mixing conductive particles (for example, carbon black, tin oxide particles, etc.) into a binder and coating the mixture is used. Can be used. The thickness of the conductive surface layer is preferably from 1 to 30 μm. The shape of the support is preferably, for example, a cylindrical shape or a film shape.
[0041]
An undercoat layer having a barrier function or an adhesive function may be provided between the support or the conductive surface layer and the photosensitive layer, if necessary. The undercoat layer can be formed of, for example, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The thickness of the undercoat layer is preferably 5 μm or less, more preferably 0.5 to 3 μm. The undercoat layer preferably has a resistivity of 10 ⁷ Ω · cm or more.
[0042]
Further, between the support and the undercoat layer, it is preferable to provide a coating layer for defects of the support and a conductive layer for the purpose of preventing interference fringes due to scattering when image input is laser light, if necessary. . The conductive layer can be formed by dispersing and applying a conductive powder such as carbon black, metal particles, and metal oxide in a binder resin. The thickness of the conductive layer is 5 to 40 μm, preferably 10 to 30 μm.
[0043]
A protective layer may be provided on the photosensitive layer as needed. The protective layer is made of a resin such as polyvinyl butyral, polyester, polycarbonate (polycarbonate Z, modified polycarbonate, etc.), nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer or the like. It can be formed by dissolving with a solvent, coating and drying on the photosensitive layer. The thickness of the protective layer is preferably 0.05 to 20 μm. Further, the protective layer may contain conductive particles, an ultraviolet absorber, and the like. As the conductive particles, for example, metal oxides such as tin oxide particles are preferable.
[0044]
Next, an electrophotographic apparatus using the electrophotographic photoreceptor of the present invention will be described.
[0045]
In FIG. 11, reference numeral 11 denotes a drum type photoreceptor of the present invention, which is driven to rotate at a predetermined peripheral speed in the direction of an arrow around a shaft 11a. The photoreceptor 11 receives a uniform charge of a predetermined positive or negative potential on the peripheral surface thereof by a charging means 12 in the course of its rotation, and then, in an exposure section 13, a light image exposure L (slit exposure or laser Beam scanning exposure). As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor. The electrostatic latent image is then developed with toner by developing means 4, and the developed toner image is transferred by a corona transfer means 5 from a paper feeding unit (not shown) between the photosensitive body 11 and the transfer means 5. The recording material 9 is sequentially transferred to the surface of the recording material 9 which is fed synchronously. The recording material 9 to which the image has been transferred is separated from the surface of the photoreceptor, introduced into the image fixing means 8, subjected to image fixing, and printed out of the apparatus as a copy. The surface of the photoreceptor 11 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 6, subjected to a charge removal treatment by the pre-exposure means 7, and used repeatedly for image formation. As the uniform charging means 12 for the photoreceptor 11, a corona charging device is generally widely used.
[0046]
Further, as shown in FIGS. 12 and 13, the charging of the photoconductor 11 may be performed by using the direct charging member 10 as a charging unit and bringing the direct charging member 10 to which the voltage is applied into contact with the photoconductor 11 ( This charging method is hereinafter referred to as direct charging). In the apparatus shown in FIGS. 12 and 13, the toner image on the photoconductor 11 is also directly transferred to the recording material 9 by the charging member 23. That is, the toner image on the photoconductor 11 is transferred to the recording material 9 by bringing the direct charging member 23 to which the voltage is applied into contact with the recording material 9.
[0047]
In the apparatus shown in FIG. 12, at least the photosensitive member 11, the direct charging member 10 and the developing means 4 are housed in a container 20 to form one electrophotographic apparatus unit, and this apparatus unit is used by using a guide means such as a rail of the apparatus body. It is configured to be detachable. The cleaning means 6 may or may not be disposed in the container 20.
[0048]
Further, in the apparatus shown in FIG. 13, at least the photoconductor 11 and the direct charging member 10 are housed in a first container 21 to form a first electrophotographic apparatus unit, and at least the developing means 7 is housed in a second container 22. A second electrophotographic apparatus unit is provided, and the first apparatus unit and the second apparatus unit are configured to be detachable. The cleaning means 6 may or may not be disposed in the container 21.
[0049]
In the case where the electrophotographic apparatus is used as a copier or a printer, the light image exposure L uses the reflected light or transmitted light from the original, or scans and emits a laser beam according to the read signal of the original according to a signal. This is performed by driving a diode array or a liquid crystal shutter array.
[0050]
The electrophotographic photoreceptor of the present invention can be widely used in electrophotographic application fields such as laser beam printers, electrophotographic copiers, CRT printers, LED printers, liquid crystal printers, and laser plate making.
[0051]
The electrophotographic photoreceptor of the present invention described above has excellent potential stability and can prevent the occurrence of black spots under high temperature and high humidity even if it is repeatedly used, without impairing the high sensitivity characteristic of TiOPc.
[0052]
【Example】
"Parts" shown below means "parts by weight".
[0053]
Reference Example 1
50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resole type phenol resin, 20 parts of methyl cellosolve, 5 parts of methanol, and silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, average molecular weight 3000) 0.002 parts were dispersed in a sand mill using 1 mmφ glass beads for 2 hours to prepare a coating for the conductive layer, and this coating was applied by dip coating to the outer periphery of an aluminum cylinder (80 mm in outer diameter and 360 mm in length). After drying at 140 ° C. for 30 minutes, a conductive layer having a thickness of 20 μm was formed.
[0054]
A solution obtained by dissolving 5 parts of a 6-66-610-12 quaternary polyamide copolymer (Amilan CM8000, manufactured by Toray) in a mixed solvent of 70 parts of methanol and 25 parts of butanol is applied onto the conductive layer by dip coating, and dried. Thus, an undercoat layer having a thickness of 1 μm was formed.
[0055]
6 parts of I-type TiOPc and 4 parts of the bisazo pigment of Pigment Example 1 described above were added to a solution of 10 parts of polyvinyl butyral (trade name: SREC BX-1, manufactured by Sekisui Chemical) in 400 parts of cyclohexanone, and 1 mmφ glass beads were used. The mixture was dispersed in a sand mill for 3 hours, 400 parts of ethyl acetate was added thereto, and the mixture was diluted and collected. This was dip-coated on the undercoat layer, dried at 80 ° C. for 10 minutes, and dried to a film thickness of 0.25 μm. Was formed.
[0056]
10 parts of a charge transport material having the following structural formula,
[Outside 8]

[0057]
A solution prepared by dissolving 10 parts of bisphenol Z-type polycarbonate in 60 parts of chlorobenzene is applied to the charge generation layer by dip coating, and dried at 110 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm. An electrophotographic photosensitive member according to Reference Example 1 of the present invention was prepared.
[0058]
The electrophotographic photoreceptor prepared in Reference Example 1 was mounted on a laser beam printer (trade name: LBP-SX, manufactured by Canon Inc.), the potential of the dark portion was set to -700 V, and the dark portion was irradiated with a laser beam of 802 nm to obtain a light. The sensitivity was compared by measuring the amount of laser light at which the partial potential became -150 V. Further, the amount of change in the dark area potential (ΔV _D ) and the amount of change in the light area potential (ΔV _L ) during continuous copying of 5000 sheets were measured. Further, under a high-temperature and high-humidity environment at a temperature of 35 ° C. and a humidity of 90%, a white image was output on the entire surface to evaluate the degree of black spots.
[0059]
Table 1 shows the results. The evaluation in the black spot column in the table was evaluated by comparing the degree of occurrence of the black spot with a reference sample representing six levels, where 0 indicates no black spot and 5 indicates the black spot in the entire image area. Has occurred and the entire image area looks gray. Therefore, the frequency of occurrence of black spots increases as the numerical value increases from 0 to 5. As for the evaluation of black spots, 0 to 2 can be used for practical use.
[0060]
[Table 1]

Reference Example 2
Instead of bisazo pigment 4 parts of type I TiOPc6 parts and pigment Example 1 of Reference Example 1 was adjusted Type I TiOPc dispersions other contains type I TiOPc10 parts in the same manner as in Reference Example 1. Also, 10 parts of the bisazo pigment of Pigment Example 1 described above was used in place of 6 parts of the I-type TiOPc of Reference Example 1 and 4 parts of the bisazo pigment of Pigment Example 1, and the rest was the same as in Reference Example 1, except that Was adjusted.
[0061]
The above-mentioned bisazo pigment dispersion is applied to a thickness of 0.1 μm on the conductive layer and the subbing layer prepared in the same manner as in Reference Example 1, and the above-mentioned TiOPc dispersion is further coated thereon. The charge generation layer was formed by spray coating to a thickness of 0.25 μm. The charge transport layer was formed in exactly the same manner as in Reference Example 1 to prepare an electrophotographic photoreceptor according to Reference Example 2 of the present invention.
[0062]
Reference Example 3
An electrophotographic photosensitive member was prepared in exactly the same manner as in Reference Example 2, except that the order of applying the bisazo pigment dispersion and the TiOPc dispersion in Reference Example 2 was reversed.
[0063]
The electrophotographic photosensitive members prepared in Reference Examples 2 and 3 were evaluated as in the case of the electrophotographic photosensitive member of Reference Example 1. Table 2 shows the results.
[0064]
[Table 2]

[0065]
As can be seen from the results, in the electrophotographic photoreceptor in which the specific bisazo pigment according to the reference example of the present invention is laminated, the repetition characteristics and the occurrence of black spots are improved, but the charge generation layer containing the bisazo pigment is conductively supported. It is more preferable to provide it on the body side.
[0066]
Example 1
A conductive layer and an undercoat layer were formed on an aluminum cylinder in exactly the same manner as in Reference Example 1.
[0067]
Next, using a bisazo pigment of the pigment Example 2 above and in place of the bisazo pigment of the pigment Example 1 used in Reference Example 1, and the other, a charge generating layer in the same manner as in Reference Example 1, to form a charge transport layer Thus, an electrophotographic photosensitive member of the present invention was prepared.
[0068]
The electrophotographic photosensitive member of Example 1 was mounted to the improved direct charging system manufactured by Canon laser beam printer LBP-SX, it was evaluated in the same manner as in Reference Example 1. A DC voltage of -720 V and an AC voltage of 1500 V between peaks were superimposed and applied to the direct charging member of the laser beam printer, and the dark portion potential of the electrophotographic photosensitive member was set to -700 V. Table 3 shows the evaluation results.
[0069]
[Table 3]

As can be seen from the results, in the electrophotographic photoreceptor in which the specific bisazo pigment according to the present invention is laminated, the repetition characteristics and the occurrence of black spots are improved.
[0070]
【The invention's effect】
The present invention has a remarkable effect that an electrophotographic photoreceptor using TiOPc as a charge generation layer has improved repetition characteristics and image defects under high temperature and high humidity, and can provide high sensitivity and high quality images.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction diagram of type I oxytitanium phthalocyanine.
FIG. 2 is an X-ray diffraction diagram of α-type oxytitanium phthalocyanine.
FIG. 3 is an X-ray diffraction diagram of β-oxytitanium phthalocyanine.
FIG. 4 is an X-ray diffraction diagram of Y-type oxytitanium phthalocyanine.
FIG. 5 is an example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 6 is another example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 7 is another example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 8 is another example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 9 is another example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 10 is another example of a layer configuration of the electrophotographic photosensitive member of the present invention.
FIG. 11 is a diagram illustrating an example of the electrophotographic apparatus of the present invention.
FIG. 12 is a view showing another example of the electrophotographic apparatus of the present invention.
FIG. 13 is a view showing another example of the electrophotographic apparatus of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 charge transport layer 2 charge transport layer 3 support 4 developing means 5 transfer means 6 cleaning means 7 pre-exposure means 8 fixing means 9 recording material 10, 23 direct charging member 11 photoreceptor 12 charging means 13 exposure unit

Claims (13)

An electrophotographic photosensitive member having at least a photosensitive layer on a support, wherein the photosensitive layer contains oxytitanium phthalocyanine and a bisazo pigment represented by the following general formula (II) .

The oxytitanium phthalocyanine has peaks at least at Bragg angles (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 ° and 27.1 ° in characteristic X-ray diffraction of CuKα. The electrophotographic photosensitive member according to claim 1 . 3. The electrophotograph according to claim 1 , wherein the oxytitanium phthalocyanine has peaks at least at Bragg angles (2θ ± 0.2 °) of 7.6 ° and 28.6 ° in CuKα characteristic X-ray diffraction. Photoconductor. 2. The electrophotographic photosensitive member according to claim 1, wherein the oxytitanium phthalocyanine has peaks at least at Bragg angles (2θ ± 0.2 °) of 9.3 ° and 26.3 ° in characteristic X-ray diffraction of CuKα. body. 2. The electrophotographic photosensitive material according to claim 1, wherein the oxytitanium phthalocyanine has peaks at least at Bragg angles (2θ ± 0.2 °) of 9.5 ° and 27.3 ° in characteristic X-ray diffraction of CuKα. body. The photosensitive layer is formed by laminating at least a charge generation layer and a charge transport layer, and wherein the oxytitanium phthalocyanine in the charge generation layer, any one of claims 1 to 5 containing a bisazo pigment of the formula (II) 2. The electrophotographic photoreceptor according to 1. The electrophotographic photosensitive member according to claim 6 , wherein the charge generation layer is a single layer. The electrophotographic photoreceptor according to claim 6 , wherein the charge generation layer is formed by laminating a first charge generation layer containing the bisazo pigment and a second charge generation layer containing the oxytitanium phthalocyanine. The electrophotographic photosensitive member according to claim 8, wherein the second charge generation layer is in contact with the charge transport layer. Image forming the electrophotographic photosensitive member according to any one of claims 1 to 9, a charging means for charging said electrophotographic photosensitive member, an electrostatic latent image performs image exposure to the charged the electrophotographic photosensitive member An electrophotographic apparatus comprising: an exposing unit; and a developing unit that develops the electrophotographic photosensitive member on which an electrostatic latent image is formed with toner. The electrophotographic apparatus according to claim 10 , wherein the charging unit is a direct charging member. An electrophotographic photosensitive member according to any one of claims 1 to 9, an electrophotographic apparatus unit in contact with said electrophotographic photosensitive member and having a direct charging member for charging said electrophotographic photosensitive member. 13. The electrophotographic apparatus unit according to claim 12, further comprising a developing unit for developing an electrostatic latent image formed on the electrophotographic photosensitive member.

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