JP3985664B2 - Method for manufacturing belt-shaped electrophotographic photosensitive member, belt-shaped electrophotographic photosensitive member, and image forming apparatus - Google Patents

Description

【００５７】
【化２】

ここで、式（２）中、「Ｒ」はアルキル基を示す。
【００５８】
【化３】

【００５９】
【化４】

【００６０】
【化５】

【００６１】
【化６】

【００６２】
【化７】

【００６３】
【化８】

【００６４】
【化９】

【００６５】
【化１０】

ここで、式（１０）中、「Ｒ」はアルキレン基を示す。
【００６６】
そして、この第１工程では、図１及び図２に示すように、環状体５を塗布液２に浮かべ、環状体５の孔６内を通して芯体１を塗布液２中に浸漬させ、次いで、芯体１を塗布液２から引き上げる。塗布液２からなる塗膜４を芯体１上によりスムーズに形成する観点から、引き上げ速度は、芯体１の長手方向の長さを基準として表現すると、０．１〜２ｍ／ｍｉｎ程度であるのが好ましい。
【００６７】
ここで、環状体５の孔６を通して芯体１を引き上げる際に、環状体５の孔６と芯体との間に介在する塗布液２により、芯体１と環状体５との間に摩擦抵抗が生じ、環状体５は少し持ち上げられる。環状体５が持ち上げられると、環状体５は芯体との摩擦抵抗が孔６の周方向で一定になるように水平方向（塗布液の液面の面方向）に移動するので、環状体５と芯体１との間の間隙ｄ１６が一定となるように調節される。例えば、芯体１を引き上げる際に、上記の間隙ｄ１６が変化した場合、ある間隙ｄ１６の部分では摩擦抵抗が大きくなり、その反対側の間隙ｄ１６の部分では摩擦抵抗が小さくなる不均衡状態が生じる。
【００６８】
しかしこの場合にも、環状体５は芯体１との摩擦抵抗が孔６の周方向で一定になるように水平方向に移動するので、摩擦抵抗が大きな間隙ｄ１６の部分は広くなるように、摩擦抵抗が小さな間隙ｄ１６の部分は狭くなるように環状体５が水平方向に移動し、環状体５と芯体１との間の間隙は一定となる。すなわち、環状体５の孔６を通して芯体１を引き上げる際には、環状体５が芯体１と接触することはなく、しかも、環状体５の孔６と芯体１とは常に一定の間隙が保たれる。
【００６９】
そのため、芯体１がその中心軸と塗布液２の液面の法線方向とが平行にならず多少傾いている状態にあったり、振動している状態にあっても、環状体５は芯体１の動きに追随して水平方向（塗布液の液面の面方向）に動きうるので、芯体１上に塗布液２からなる液体状の膜４（以下、塗膜４という）を均一な厚さで容易に形成できる。
従って、第１工程において上述の作業を行うようにすれば、均一な厚さを有するシームレス基体ベルト１０を芯体１上に容易に形成できる。
【００７０】
次に、第２工程について説明する。
第２工程においては、先ず、芯体１の表面に付着した塗布液２からなる液体状の塗膜４を乾燥させ、導電性材料とＰＩ前駆体とを少なくとも含む固体状のＰＩ前駆体膜（図示せず）を形成する。
【００７１】
ここで、乾燥の際の温度条件は、５０〜１２０℃であることが好ましく、乾燥時間は３０〜２００分であることが好ましい。なお、塗布液２に使用する溶剤として非プロトン系極性溶剤を使用した場合には、塗膜４の乾燥が極めて遅くなるので、乾燥中に塗膜４又はこれから得られるＰＩ前駆体膜は自身にかかる重力の影響を受けて、いわゆる「垂れ」が生じやすくなる。この場合には、塗布された芯体１を、その長手方向を水平（重力のかかる方向と垂直な方向）となるようにして、１０〜６０ｒｐｍ程度の回転速度で回転させながら乾燥することが好ましい。
【００７２】
次に、得られるＰＩ前駆体膜を加熱してＰＩ前駆体の縮合反応を進行させ、導電性材料とＰＩを少なくとも含む膜からなるシームレス基体ベルト１０を形成する。
【００７３】
ここで、加熱の温度条件は、３００〜４５０℃の温度であることが好ましい。また、加熱時間は２０〜６０分間であることが好ましい。このように、ＰＩ前駆体皮膜を加熱して、ＰＩ前駆体の縮合反応を進行させるとシームレス基体ベルト１０が形成される。その際、先に述べたように、ＰＩ前駆体皮膜又はシームレス基体ベルト１０中に溶剤が残留していると、シームレス基体ベルト１０に膨れを生じることがあるため、完全に溶剤を除去することが好ましい。また、シームレス基体ベルト１０の膨れの発生をより確実に防止する観点から、加熱時には、温度を急激に上昇させるのではなく、段階的に上昇させたり、適度な一定の昇温速度でゆっくりと上昇させることが好ましい。
【００７４】
また、シームレス基体ベルト１０の厚さは、後述の第４工程において得られるベルト状電子写真感光体２０を屈曲させて使用する場合には４０〜１００μｍとすることが好ましく、ベルト状電子写真感光体２０を円筒状の基体に嵌めた状態で使用する場合には２０〜５０μｍ程度とすることが好ましい。このベルト状電子写真感光体２０の厚さを考慮して、前述の芯体１の表面に付着した塗布液２からなる液体状の塗膜４の厚さを調節する。具体的には、例えは、前述した第１工程における塗布液２の粘度や組成成分の構成、芯体１と環状体５との間の間隙ｄ１６の大きさの調節や、第１工程を数回繰り返して、塗布液２の塗布回数を調節することなどが挙げられる。
【００７５】
次に、第３工程について説明する。
第３工程は芯体１とシームレス基体ベルト１０とが一体化された状態を保持したまま、顔料を少なくとも含む感光層形成用の塗布液をシームレス基体ベルトの表面に塗布して感光層を形成する工程である。
【００７６】
図３は本発明にかかる第３工程を行うための浸漬塗布装置の基本構成の一例を示す模式断面図である。また、図４は本発明のベルト状電子写真感光体の好適な一実施形態の基本構成を示す模式断面図である。但し、図３には第３工程を行う際の装置要部のみを示し、他の構成要素は省略した。
【００７７】
図３に示すように、第３工程を行うための浸漬塗布装置２００は、主として、顔料を少なくとも含む感光層形成用の塗布液１２を収容する塗布槽１３と、第３工程において得られたシームレス基体ベルト１０が形成された芯体１と、芯体１を取り外し可能に保持する保持手段（図示せず）とから構成されている。
更に、芯体１の保持手段は、第１工程で説明した浸漬塗布装置の保持手段と同様に、芯体１を保持しつつ、塗布液１２の液面の法線方向に対して芯体１の中心軸が略平行となる方向に芯体１を上下動させることが可能なリフト機構（図示せず）を備えている。この保持手段のリフト機構により芯体１の塗布液１２中への浸漬或いは塗布液２中からの引き上げが可能になる。
【００７８】
また、浸漬塗布装置２００は、塗布液１２を塗布槽１３に溜め置く構成としてもよいが、塗布槽１３の下部から供給し、上部から溢流させて回収し、ポンプで循環させる構成としてもよい。その場合、循環経路にはフィルター、粘度計、希釈液追加装置等を付加することが有効である。
【００７９】
ここで、芯体１を塗布液１２に浸漬した時に、芯体１の表面部分にシームレス基体ベルト１０が密着して形成されていない露出領域があると、その領域に塗布液１２が付着する。例えば、シームレス基体ベルト１０の一部が剥がれて該シームレス基体ベルト１０と芯体１との間に隙間がある場合、その隙間に塗布液１２が侵入することになり、後述の第４工程においてシームレス基体ベルト１０が芯体１から取り外せなくなったり、芯体１の再利用ができないという問題が生じる。
【００８０】
そのため、この第３工程においては、芯体１の表面のうち感光層形成用の塗布液１２中に浸漬させた際に該塗布液１２に接触可能となる領域には、該塗布液１２との接触を防止するための被覆材１１による被覆処理を予め施し、次いで、芯体１を該塗布液１２中に浸漬させることが好ましい。
【００８１】
特に、シームレス基体ベルト１０と一体化した芯体１の下端となる側の表面部分にシームレス基体ベルト１０が密着して形成されていない露出領域があると、上記の問題は顕著に発生するため、図３に示すように、芯体１の下端となる側の表面部分は被覆材１１を用いて被覆することが好ましい。被覆材１１としては、例えば、粘着テープ等が挙げられる。粘着テープを芯体１の下端となる側の表面部分に巻回することにより該表面部分を被覆して芯体１の表面と塗布液１２との接触を充分に防止することができる。
【００８２】
被覆材１１を用いた他の被覆方法としては、例えば、被覆材１１として幅広のゴムバンド用いこれを引き伸ばして拡張し、シームレス基体ベルト１０と一体化した芯体１の被覆すべき部位（例えば、上記の芯体１の下端となる側の表面部分）に被せる方法、芯体１の下端となる側の表面部分全体を覆う形状を有するキャップ（例えば、ゴム製のキャップ）を取り付ける方法等が挙げられる。
これにより、均一な厚さを有する感光層１５をより確実に形成することができる。
【００８３】
また、図３に示すように、第３工程において、シームレス基体ベルト１０と一体化した芯体１を塗布液１２に浸漬した後、該芯体１を引き上げることにより、シームレス基体ベルト１０の表面に、塗布液１２からなる液体状の膜１４（以下、「塗膜１４」という）が形成される。このときの芯体１の引き上げ速度は、形成すべき感光層１５の厚さにもよるが、５０〜５００ｍｍ／分が好ましい。
【００８４】
引き上げ後、塗膜１４を乾燥させて塗膜１４から溶剤を除去することにより感光層１５が形成される。ここで、乾燥前又は乾燥後に、先に形成した被覆材１１を取り外す。また、浸漬塗布の作業を複数回繰り返す場合には、１度の浸漬塗布ごとに被覆材１１を取り外すのではなく、最後の浸漬塗布の作業を終了した後の乾燥又は乾燥後に取り外してもよい。
【００８５】
なお、感光層１５の構成としては、いわゆる単層型であってもよく、電荷発生層と電荷輸送層からなるいわゆる積層型であってもよい。従って、塗布液１２の成分組成も形成すべき感光層１５の構成に合わせて決定される。例えば、単層型の場合には、塗布液１２は１種類調製すればよいが、積層型の場合には、電荷発生層の構成と電荷輸送層の構成にそれぞれ合わせた２種類の塗布液１２を調製する必要があり、浸漬塗布及び乾燥の作業もそれぞれの層を形成するために少なくとも１回づつ行う必要がある。
【００８６】
上記の塗布液１２の構成を決める単層型感光層としては、主に電荷発生顔料を樹脂に分散したものと、電荷輸送層中に電荷発生顔料を分散したものがある。
【００８７】
また、上記の塗布液１２の構成を決める積層型感光層の電荷発生層としては、光を吸収して電荷を発生するフタロシアニン等の顔料と、ポリビニルブチラール樹脂等の結着剤とを含む層が挙げられ、その厚さは０．０１〜１μｍであることが好ましい。また、電荷輸送層としては、ヒドラゾン化合物、スチルベン化合物、ベンジジン化合物、ブタジエン化合物、トリフェニルアミン化合物等の電荷輸送性材料と、ポリカーボネート等の結着剤樹脂とをとを含む層挙げられ、その厚さは、通常１５〜４０μｍであることが好ましい。
【００８８】
次に、第４工程について説明する。第４工程は芯体１をシームレス基体ベルト１０から取り外す工程である。これにより、ベルト状電子写真感光体２０を得ることができる。
【００８９】
なお、第４工程の終了後、必要に応じて、ベルト状電子写真感光体２０の端部の長さを揃えるための切断加工、電極の取り付け加工、位置の案内部材の取り付け加工、特性検査等を施してもよい。
【００９０】
次に、本発明のベルト状電子写真感光体の使用方法の一例について、ベルト状電子写真感光体２０を例にして説明する。
【００９１】
ベルト状電子写真感光体２０は、複数のロールに架けて使用してもよく、円筒基体の外周面に嵌めて使用してもよい。円筒基体に嵌めて使用する場合、ベルト状電子写真感光体２０を円筒基体に嵌合させる方法としては、接着剤や粘着テープを使用してもよいが、円筒基体を冷却してその体積を収縮させ、そこにベルト状電子写真感光体を嵌合させる方法が好ましい。円筒基体を常温に戻せば、体積が膨張するため強い摩擦力でベルト状電子写真感光体が円筒基体の外周面に固定されることとなる。なお、このような場合でも、ＰＩ樹脂は引っ張り強度が高いので、裂けにくい利点がある。
【００９２】
この用途の円筒基体としては、アルミニウムやステンレス等の金属製円筒体、フェノール樹脂やポリアセタール樹脂等のプラスチック製の円筒体が挙げられる。ここで、円筒基体の外径は、常温におけるベルト状電子写真感光体２０の内径よりわずかに大きく、冷却した際にベルト状電子写真感光体２０の内径より小さくなる値であればよい。また、嵌合させる際の冷却温度は、円筒基体の構成材料の熱膨張率にもよるが、−２００〜−２０℃が好ましい。嵌合させる際の冷却方法としては、液体窒素（約−１９６℃）や液体空気（約−１９０℃）等に代表される−７０℃以下の液体状態の冷媒に円筒基体を浸漬する方法が好ましい。
【００９３】
ベルト状電子写真感光体２０を円筒基体に嵌合させて使用する場合、例えば、ベルト状電子写真感光体２０が寿命となった場合は、円筒基体を再び冷却することにより、使用済みのベルト状電子写真感光体２０を円筒基体から容易に取り外すことができる。そして、円筒基体が冷却されている間に、新しいベルト状電子写真感光体２０を再び嵌合させれば、交換作業を非常に簡単に行うことができる。また、これにより、従来は感光層の剥離に手間がかかるため廃棄され再利用され難かった円筒基体を容易に再利用することが可能となる。
【００９４】
ベルト状電子写真感光体２０を使用する際に、電圧を印加した導電性のロールやブラシを接触させて行う接触帯電方式を採用した場合、先に述べたように、導電性基体の体積抵抗率を１０⁵〜１０¹⁰Ωｃｍにしておけば、放電破壊を生じることなく感光体２０の帯電を行うことができる。なお、ベルト状電子写真感光体２０を複数のロールに架けて使用する場合、接触帯電器の位置にロールを配置することが好ましい。
【００９５】
また、本発明の画像形成装置は、本発明の電子写真感光体を搭載する装置であり、感光体を搭載することにより優れた出力画像品質を得ることができる。本発明の画像形成装置は、本発明の電子写真感光体の他に、電子写真感光体を帯電させる帯電手段と、帯電手段により帯電される電子写真感光体を露光して静電潜像を形成する露光手段と、静電潜像をトナーにより現像してトナー像を形成する現像手段と、トナー像を被転写媒体に転写する転写手段と、を備える構成を有していれば、他の構成については特に限定されない。
【００９６】
以上、本発明の好適な実施形態について詳細に説明したが、本発明は上記実施形態に限定されるものではない。
【００９７】
例えば、上記実施形態において、保護層を更に設けてもいい。この場合、第３工程の終了後、芯体１、シームレス基体ベルト１０及び感光層１５が一体化したものの感光層１５の表面に、別途調製した保護層形成用の塗布液を塗布する。ここで、この場合、感光層１５形成用の塗布液１２のかわりに保護層形成用の塗布液を用いること以外は、上述の第３工程と同様の手順で保護層を形成することが好ましい。
【００９８】
また、上記実施形態において、下引層を更に設けてもいい。この場合、第２工程の終了後、芯体１、シームレス基体ベルト１０が一体化したもののシームレス基体ベルト１０の表面に、別途調製した下引層形成用の塗布液を塗布する。ここで、この場合、感光層１５形成用の塗布液１２のかわりに下引層形成用の塗布液を用いること以外は、上述の第３工程と同様の手順で下引層を形成することが好ましい。そして、下引層の形成後、感光層を形成する場合には、下引層の表面に感光層を形成すること以外は上述の第３工程と同様の手順で感光層を形成することが好ましい。
【００９９】
下引層を設ける場合、その厚さは通常０．１〜５μｍであるが、感光層の放電破壊を防止するために、層中に粉体を分散させて、５〜３０μｍに厚くする場合もある。それに用いられる粉体には、酸化チタン、酸化亜鉛、酸化錫、酸化アルミニウム、酸化ジルコニウム、酸化セリウム等の金属酸化物があり、これ以外の粉体を併用してもよい。また、下引層に含有される樹脂としては、タイプ８ナイロンや共重合ナイロン等のアルコール可溶性ナイロン、４級アンモニウム塩等の導電性ポリマー、カゼイン、ポリウレタン、ポリエステル、ポリビニルアルコール、ポリビニルブチラール、ポリビニルアセタール等がある。
また、下引層を設ける場合、導電性基体の体積抵抗率は、その下引層と合わせて１０⁵〜１０¹⁰Ωｃｍとなるようにすれば接触帯電にも都合よい。
【０１００】
また、本発明の第１工程は上述した実施形態の第１工程に限定されず、例えば、第１工程は以下のような装置を用いて行ってもよい。図５は、図１に示した本発明にかかる第１工程を行うための浸漬塗布装置の基本構成の他の一例を示す模式断面図である。図５に示す浸漬塗布装置１００Ａは、図１に示した塗布槽３のかわりに環状塗布槽７を備えていること以外は図１に示した浸漬塗布装置１００と同様の構成を有している。
【０１０１】
この環状塗布槽７の底部中央には、使用する芯体１の外径より大きな内径を有する円形状の開口部７１が形成されている。また、環状塗布槽７の底部の外側の面には、使用する芯体１の外径以下の内径を有する円形状の開口部８１が形成された環状体からなるシール材８（例えば、ゴムパッキン等）が配置されている。このシール材８は、環状塗布槽７の開口部７１から塗布液２が外部に漏れ出るのを防止するための部材である。
【０１０２】
そして、第１工程において、芯体１は開口部７１から環状塗布槽７内に挿入される。そしてその後、環状塗布槽７内に上部の開口部から塗布液２が充填される。このとき、環状塗布槽７の底部には、シール材８が配置されているので塗布液２が外部に漏れないようになっている。基体１はその穴を通して、環状塗布槽の下部から上部に順次つき上げられ、かつ塗布液１２の液面に浮かぶ環状体５の孔６内を通過することにより、その表面に塗膜４が形成される。
【０１０３】
ここで、図５に示したように、芯体１の上部または下部に芯体１とほぼ同じ外径を有しかつ所定の長手方向の長さを有する円柱状の蓋部材９を取り付けてもよい。これにより、芯体１を塗布液２の液面上に引き上げても、環状塗布槽７の開口部７１から塗布液２が外部に漏れ出るのを防止することができる。
図５に示した環状塗布槽７を用いた方法では、環状塗布槽７の容積を図１に示した塗布槽３の容積よりも大幅に小さくすることができる利点がある。
【０１０４】
【実施例】
以下、実施例を挙げて本発明の内容をさらに詳しく説明するが、本発明はこれらの実施例に何ら限定されるものではない。
【０１０５】
以下に示す手順により実施例１〜実施例４のベルト状電子写真感光体を作製した。
【０１０６】
（実施例１）
ＰＩ前駆体を含む塗布液（商品名：ＵワニスＳ、宇部興産製、濃度：１８質量％、粘度：約５Ｐａ・ｓ）を用意した。この溶液（塗布液）に、カーボンブラック（商品名：Ｃｏｎｄｕｃｔｅｘ９７５、コロンビヤンカーボン社製）を溶液の固形成分に対して１８質量％となるように混合し、次いでボールミルにより２４時間分散し、シームレス基体ベルトを形成するための塗布液を調整した（以下、「塗布液２２」という）。
【０１０７】
一方、アルミニウム製円筒を用意し、その表面は球形アルミナによるブラスト処理により、Ｒａ０．８μｍに粗面化した後、表面にシリコーン系離型剤（商品名：ＫＳ７００、信越化学(株)製）を塗布し、３００℃で１時間の焼き付け処理して外径６８ｍｍ、長さ４００ｍｍの芯体とした。
【０１０８】
図２に示した環状体５と同様の形状を有する環状体として、外径が８０ｍｍ、最上部の内径が６９．２ｍｍのアルミニウム製環状体を用意した。また、図５に示した環状塗布槽７と同様の構成を有する環状塗布槽（内径：１００ｍｍ、高さ：５０ｍｍ、底面の開口部の内径：７０ｍｍ）を用意した。更に、この環状塗布槽の底面に内径６７ｍｍの開口部を設けた厚さ０．５ｍｍの軟質ポリエチレン製のシール材を取り付けた。
【０１０９】
次に、芯体の一端に、外径６８ｍｍ、長さ６０ｍｍの円柱状のポリエーテル樹脂製の蓋部材を取り付け、更に、環状塗布槽の底部の開口部の側から蓋部材を取り付けた芯体を挿入した。なお、このとき、芯体は蓋部材の取り付けていない端部の側から挿入した。また、このとき、環状体を予め芯体を環状塗布槽内に配置しておき、芯体を環状体の孔内にも挿入した。
【０１１０】
その後、環状塗布槽に塗布液２２を入れ、塗布液２２の液面からの環状体の上昇高さが約５ｍｍになるよう、上昇速度を０．９〜０．７ｍ／ｍｉｎに調整しながら、芯体１を引き上げて、塗布液２２の塗布を行った。その際、環状体５は芯体と接触することはなかった。
【０１１１】
塗布液２２の塗布後、芯体には厚さが約６００μｍのＰＩ前駆体を含む液体状の膜が形成された。次いで、芯体を水平方向（その中心軸の方向が引き上げ方向に対して垂直となる方向）に傾けて２０ｒｐｍで回転させながら、１３０℃で６０分間乾燥し、次いで、２００℃で３０分間、３５０℃で３０分間加熱した。これにより、厚さ７５μｍのＰＩ樹脂を含む膜からなるシームレス基体ベルトが形成された。このシームレス基体ベルトの体積抵抗率は約１０⁵Ωｃｍであった。
【０１１２】
ここで、シームレス基体ベルトには収縮が生じ、芯体の両端には幅が約８ｍｍの露出部分が生じた。シームレス基体ベルトを芯体から取り外すことなく、次に下引層形成用の塗布液に浸漬する際のシームレス基体ベルトの下端側となる露出部分に、幅２０ｍｍのポリエステルテープ（商品名：Ｎｏ．３１Ｂ、日東電工製）を芯体の端部に合わせて一周巻き付け、芯体の露出部分と、該露出部分の近傍のシームレス基体ベルトの端部とを被覆した。
【０１１３】
次いで、８ナイロン（ラッカマイド、大日本インキ化学社製）５質量部をメタノール４０質量部および１−ブタノール６０質量部の混合溶媒に溶解し、下引層形成用の塗布液（以下、「塗布液２３」という）を調製した。この塗布液を図３に示した塗布槽１３と同様の形状を有する塗布槽（内径：９０ｍｍ、深さ：４５０ｍｍ）に入れ、その中にシームレス基体ベルトが一体化した芯体を浸漬し、０．２ｍ／ｍｉｎで引き上げることにより、シームレス基体ベルト上に塗布液２３からなる液状の膜を形成した。その後、１３５゜Ｃで１０分間の乾燥をして、厚さ０．８μｍの下引層をシームレス基体ベルト上に形成した。
【０１１４】
次に、ポリビニルブチラール樹脂（商品名：エスレックＢＭ−１、積水化学社製）１質量部をシクロヘキサノン１９質量部に溶解し、これにクロロガリウムフタロシアニン３質量部を加えてサンドミルで分散した。得られた分散液にさらに２−ブタノン２０質量部を加えて電荷発生層形成用の塗布液を調製した。この液に下引層及びシームレス基体ベルトが一体化された芯体を浸漬した以外は上述の下引層と同様の手順により、下引層上に厚さ０．１μｍの電荷発生層を形成した。
【０１１５】
続いて、電荷輸送剤であるＮ，Ｎ’−ジフェニル−Ｎ，Ｎ’−（ｍ−トリル）ベンジジン４０質量部と重量平均分子量が４万のポリカーボネートＺ樹脂（商品名：ユーピロン、三菱ガス化学社製）６０質量部をジオキサン２５０部に溶解して電荷輸送層形成用の塗布液を調製した。この液に下引層、シームレス基体ベルト及び電荷発生層が一体化された芯体を浸漬し、１３５℃で４０分間の加熱乾燥をして、電荷発生層上に厚さ２３μｍの電荷輸送層を形成した。
【０１１６】
これらの作業により、ベルト状電子写真感光体を得ることができた。得られた感光体は、両端部の不規則部分を切り取り、幅３１５ｍｍのベルトとし、２本の１０ｍｍφロールに張架して使用することができた。
【０１１７】
次に、このベルト状電子写真感光体をフルカラープリンター（商品名：Docu Print C2220、富士ゼロックス社製）に搭載し、プリントテストによる電子写真特性評価試験を行った。その際の帯電方法として、直流−３５０Ｖに１．８ｋＶ２ｋＨｚの交流電圧を重畳させた電圧を帯電ロールに印加し、ベルト状電子写真感光体に接触させて当該感光体を帯電させた。なお、帯電時のベルト状電子写真感光体の表面電位ＶｈをＶｈ＝−３５０Ｖとなるよう設定した。次いで、ベルト状電子写真感光体を露光し、一成分トナーにて現像をした。なお、露光時の光量は、光照射による放電後のベルト状電子写真感光体の表面電位ＶｌがＶｌ＝−６０Ｖとなるように調節した。この一連の作業を繰り返して１万枚の画像を作成したが、異常放電（リーク）に起因する黒点の発生は確認されなかった。
【０１１８】
（実施例２）
アルミニウム製円筒を用意し、実施例１と同様のブラスト処理と離型剤処理を施して外径３０ｍｍ、長さ４００ｍｍの芯体を作製した。図２に示した環状体５と同様の形状を有する環状体として、外径が５０ｍｍ、最上部の内径が３０．６ｍｍのアルミニウム製環状体を用意した。また、図５に示した環状塗布槽７と同様の構成を有する環状塗布槽（内径：８０ｍｍ、高さ：５０ｍｍ、底面の開口部の内径：３２ｍｍ）を用意した。更に、この環状塗布槽の底面に内径２８ｍｍの開口部を設けた厚さ０．５ｍｍの軟質ポリエチレン製のシール材を取り付けた。
【０１１９】
次に、芯体の一端に、外径３０ｍｍ、長さ４０ｍｍの円柱状のポリエーテル樹脂製の蓋部材を取り付け、更に、実施例１と同様にして環状塗布槽の底部の開口部の側から蓋部材を取り付けた芯体を挿入した。なお、このとき、芯体は蓋部材の取り付けていない端部の側から挿入した。
【０１２０】
その後、環状塗布槽に実施例１で使用したものと同様の塗布液２２を入れ、塗布液２２の液面からの環状体の上昇高さが約５ｍｍになるよう、上昇速度を０．９〜０．７ｍ／ｍｉｎに調整しながら、芯体１を引き上げて、塗布液２２の塗布を行った。その際、環状体５は芯体と接触することはなかった。
【０１２１】
塗布液２２の塗布後、芯体には厚さが約３００μｍのＰＩ前駆体を含む液体状の膜が形成された。次いで、芯体を水平方向（その中心軸の方向が引き上げ方向に対して垂直となる方向）に傾けて２０ｒｐｍで回転させながら、１３０℃で６０分間乾燥し、次いで、２００℃で３０分間、３５０℃で３０分間加熱した。これにより、厚さ４０μｍのＰＩ樹脂を含む膜からなるシームレス基体ベルトが形成された。このシームレス基体ベルトの体積抵抗は約１０⁵Ωｃｍであった。
【０１２２】
ここで、シームレス基体ベルトには収縮が生じ、芯体の両端には幅が約７ｍｍの露出部分が生じた。シームレス基体ベルトを芯体から取り外すことなく、次に下引層形成用の塗布液に浸漬する際のシームレス基体ベルトの下端側となる露出部分に、幅２０ｍｍのポリエステルテープ（商品名：Ｎｏ．３１Ｂ、日東電工）を芯体の端部に合わせて一周巻き付け、芯体の露出部分と、該露出部分の近傍のシームレス基体ベルトの端部とを被覆した。
【０１２３】
次いで実施例１と同様の手順により、下引層、電荷発生層、電荷輸送層を順次形成し、両端部を切り取って、幅３２０ｍｍのベルト状電子写真感光体を得た。
【０１２４】
また、外径３０．０４ｍｍ、長さ３３０ｍｍのアルミニウム製円筒基体を別途用意した。これを液体窒素に浸漬して冷却すると、外径は約２９．９２ｍｍに収縮した。その状態で、上記ベルト状電子写真感光体をこの円筒基体の外周に素早く嵌めた。常温に戻したところ、円筒基体の膨張により、ベルト状電子写真感光体は固定された。
【０１２５】
このようにして形成されたベルト状電子写真感光体は、ベルト状ではなく、通常の円筒状電子写真感光体として使用することができた。耐久性はプリント数で２万枚であり、電荷輸送層の摩耗により、寿命と判断された。その後、再び液体窒素に浸漬して冷却し、ベルト状電子写真感光体を取り外した後、実施例２の新しいベルト状電子写真感光体を同様にして嵌めることにより、アルミニウム製円筒基体を継続して使用することができた。
【０１２６】
（実施例３）
ＰＩ前駆体を含む塗布液に混合するカーボンブラックの混合量を、当該塗布液中の固形成分に対して２２質量％としたこと以外は、実施例１と同様の手順及び条件でベルト状電子写真感光体を作成した。なお、この場合のシームレス基体ベルトの体積抵抗は約１０³Ωｃｍであった。そして、実施例１と同様の条件で電子写真特性評価試験を行った。５千枚以下のプリントでは黒点の発生は確認されなかったが、一万枚を超えるプリントを繰り返して画像を作成したところ、黒点が１〜２個発生していることが確認された。その部分の感光層を調べたところ、異常放電に起因する帯電不良箇所が存在した。すなわち、接触帯電方式の場合には、５千枚以下のプリントでは実際の使用に耐えうる水準の画像を得ることができるが、シームレス基体ベルトの体積抵抗率が１０⁵Ωｃｍ未満であると、異常放電に対する防止効果が低下することが確認された。
【０１２７】
なお、このベルト状電子写真感光体と同様のベルト状電子写真感光体を作製し、帯電方式をコロナ帯電方式に変更したこと以外は上記の電子写真特性評価試験と同様の試験を行ったところ、この帯電方式の場合には異常放電（リーク）に起因する黒点の発生は確認されなかった。
【０１２８】
（実施例４）
ＰＩ前駆体を含む塗布液に混合するカーボンブラックの混合量を、当該塗布液中の固形成分に対して１５質量％としたこと以外は、実施例１と同様の手順及び条件でベルト状電子写真感光体を作成した。なお、この場合のシームレス基体ベルトの体積抵抗は約１０⁹Ωｃｍであった。そして、実施例１と同様の条件で電子写真特性評価試験を行った。１万枚の画像を作成したが、異常放電（リーク）に起因する黒点の発生は確認されなかった。
【０１２９】
【発明の効果】
以上説明したように、本発明のベルト状電子写真感光体の製造方法によれば、均一な厚さを有する感光層を容易に形成することができ、しかも高い製造効率を得ることができる。また、これにより得られる本発明のベルト状電子写真感光体は、均一な厚さを有する感光層を備えており、優れた出力画像品質を得ることができる。更に、このベルト状電子写真感光体を備える本発明の画像形成装置も、優れた出力画像品質を得ることができる。
【図面の簡単な説明】
【図１】本発明にかかる第１工程を行うための浸漬塗布装置の基本構成の一例を示す模式断面図である。
【図２】図１に示す浸漬塗布装置を芯体１の中心軸に平行な方向からみた場合の正面図である。
【図３】本発明にかかる第３工程を行うための浸漬塗布装置の基本構成の一例を示す模式断面図である。
【図４】本発明のベルト状電子写真感光体の好適な一実施形態の基本構成を示す模式断面図である。
【図５】図１に示した本発明にかかる第１工程を行うための浸漬塗布装置の基本構成の他の一例を示す模式断面図である。
【符号の説明】
１…芯体、２…基体形成用の塗布液、３…塗布槽、４…基体形成用の塗布液からなる液体状の膜、５…環状体、６…孔、７…環状塗布槽、８…シール材、９…蓋部材、１０…シームレス基体ベルト、１１…被覆材、１２…感光層形成用の塗布液、１３…塗布槽、１４…感光層形成用の塗布液からなる液体状の膜、２０・・・ベルト状電子写真感光体、７１・・・開口部、１００，１００Ａ・・・シームレス基体ベルトを形成するための浸漬塗布装置、２００・・・感光層を形成するための浸漬塗布装置、ｄ１６・・・環状体５と芯体１との間の間隙。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a belt-shaped electrophotographic photosensitive member, a belt-shaped electrophotographic photosensitive member, and an image forming apparatus equipped with the belt-shaped electrophotographic photosensitive member.
[0002]
[Prior art]
With recent downsizing and higher performance of electrophotographic equipment, it is advantageous that the organic electrophotographic photosensitive member mounted thereon has a deformable flexibility and shape. An organic electrophotographic photosensitive member (hereinafter referred to as “belt-shaped electrophotographic photosensitive member”) is preferably used.
[0003]
The belt-shaped electrophotographic photosensitive member has a configuration including at least a conductive substrate having a belt-like shape (hereinafter referred to as “substrate belt”) and a photosensitive layer disposed on the substrate belt. Such a belt-shaped electrophotographic photosensitive member is formed by applying a coating solution for forming an organic photosensitive layer containing a constituent material of an organic photosensitive layer on the outer surface of a substrate belt, and then forming a coating solution formed on the substrate. It is manufactured by drying a liquid film (hereinafter referred to as “coating film” if necessary) and removing the solvent in the coating film.
[0004]
As the base belt of such a belt-shaped electrophotographic photosensitive member, a base belt made of metal such as aluminum, copper, or nickel processed into a cylindrical shape, or a base belt made of a resin having conductivity is known. From the viewpoint of price, bendability, weight, etc., a resin base belt is preferably employed. Resin materials constituting the resin base belt include polycarbonate and polyester, but polyimide (hereinafter referred to as “PI” as necessary) is preferably employed in view of strength, dimensional stability, and the like.
[0005]
Here, in the belt-shaped electrophotographic photosensitive member, if the base belt has a seam, a defect due to the seam occurs in the output image. Therefore, it is preferable that the base belt has no seam. For this reason, various studies have been made on a manufacturing method for obtaining a high-quality photoconductor, particularly for a belt-shaped electrophotographic photoconductor provided with a so-called “seamless base belt”.
[0006]
A method for producing such a belt-shaped electrophotographic photosensitive member mainly includes a step of forming a seamless base belt and a step of forming a photosensitive layer. Further, other steps such as a step of providing a so-called undercoat layer between the substrate belt and the photosensitive layer and a step of providing a so-called protective layer on the outer surface of the photosensitive layer may be further added as necessary.
[0007]
Specifically, for example, as a method for producing a seamless base belt made of PI resin, a PI precursor is a main component on the inner surface of a cylindrical body serving as a support for forming a seamless base belt made of PI resin. A method of forming a PI resin coating film (film that becomes a seamless substrate belt) by applying a solution and drying while rotating to form a coating film of a PI precursor, and further heat-treating this to heat cure. A centrifugal molding method) has been proposed (for example, Patent Document 1). Further, a method (inner surface coating method) has been proposed in which a solution containing a PI precursor as a main component is spread on the inner surface of a cylindrical body (for example, Patent Document 2).
[0008]
Further, as another method for producing a seamless base belt made of PI resin, for example, a solution containing a PI precursor as a main component is applied to the outer surface of a cylindrical core body having a predetermined outer diameter and dried. A method (dip coating method) for forming a PI resin film after heating has been proposed (for example, Patent Document 3).
[0009]
Further, as a method for forming a photosensitive layer on the outer surface (or undercoat layer) of the seamless substrate belt, for example, when a ready-made seamless substrate belt is obtained and the photosensitive layer is formed on the outer surface thereof. And a holding means capable of holding the substrate belt by pressing the inner surface of the substrate belt from the inside when inserted into the substrate belt, and the substrate belt is placed in the coating solution for forming the organic photosensitive layer. A method for forming an immersion photosensitive layer (for example, Patent Document 4 and Patent Document 5) has been proposed.
[0010]
[Patent Document 1]
JP-A-57-74131
[Patent Document 2]
Japanese Patent Laid-Open No. 62-19437
[Patent Document 3]
Japanese Patent Laid-Open No. 61-273919
[Patent Document 4]
Japanese Patent Publication No. 5-68704
[Patent Document 5]
Japanese Patent No. 2595709
[0011]
[Problems to be solved by the invention]
However, in the case of a method of forming a seamless base belt made of PI resin on the inner surface of a cylindrical body as in the conventional methods described in Patent Document 1 and Patent Document 2, when the PI precursor coating film is heat-treated, There has been a problem that a complicated and multi-stage manufacturing process is required, for example, the coating film needs to be removed from the cylindrical body and replaced with a separately prepared outer mold.
[0012]
Further, in the method described in Patent Document 3 described above, it is not necessary to separately prepare and replace the outer mold, but the solution containing the PI precursor as a main component has a very high viscosity, so It was difficult to apply a uniform thickness to the surface. In the case of this method, the core precursor is rotated to discharge a solution containing the PI precursor as a main component onto the outer surface (flow coating method), and at that time, the spatula (blade) is used to form the PI precursor. A method of smoothing the coating film (blade coating method) can also be employed. However, the usual flow coating method and blade coating method have a problem that the work process becomes complicated. Further, the solution having the PI precursor as a main component on the outer surface of the rotating core is obtained by horizontally moving the discharge port of the solution discharging means having the PI precursor as a main component along the longitudinal direction of the core. However, there is a problem that spiral irregularities are formed on the surface of the coating film.
[0013]
Further, in the method of forming the photosensitive layer on the seamless substrate belt described in Patent Document 4 and Patent Document 5 described above, when the substrate belt is held by the holding means, the outer surface of the belt is swollen or the organic photosensitive layer is formed. Due to the pressure of the coating solution when immersed in the coating solution for forming, there is a problem that the belt bends inward and it is not easy to form a photosensitive layer with a uniform film thickness on the outer surface of the base belt. .
[0014]
In addition, in the above-described conventional method for producing a belt-shaped electrophotographic photosensitive member, the present inventors have found that foreign substances in the photosensitive layer are removed in a series of operations from the formation of the seamless base belt to the formation of the photosensitive layer. It was found that mixing could not be sufficiently prevented. The mixing of foreign matters greatly affects the output image quality of the organic electrophotographic photosensitive member, so it must be sufficiently prevented.
[0015]
Further, as a method for charging the photosensitive member, there is a non-contact charging method such as a corona charging method, but recently, a contact charging method in which a charging roll or the like is brought into contact with the surface of the photosensitive member is mainly used. When the photosensitive member is charged by a charging means that employs a contact charging method, discharge damage may occur due to abnormal discharge in severe cases due to the presence of foreign matter or the like. When discharge breakdown occurs in the photosensitive layer, normal image formation cannot be performed at that portion, and defects such as black spots or white spots occur on the output image. This abnormal discharge is caused by local current concentration, and is likely to occur when the substrate is made of metal.
[0016]
The present invention has been made in view of the above-mentioned problems of the prior art, and a method for producing a belt-shaped electrophotographic photosensitive member with high production efficiency capable of easily forming a photosensitive layer having a uniform thickness, and It is an object of the present invention to provide a belt-shaped electrophotographic photosensitive member having excellent output image quality and an image forming apparatus including the same.
[0017]
[Means for Solving the Problems]
The present invention is a method for producing a belt-like electrophotographic photoreceptor comprising at least a seamless belt-like conductive substrate and a photoreceptor layer containing at least a pigment and disposed on the outer surface of the substrate. ,
A substrate-forming coating solution containing at least a conductive material and a polyimide precursor is applied to the surface of a predetermined portion where a cylindrical or cylindrical core substrate is to be formed, and the substrate-forming coating solution is applied to the surface of the core. A first step of forming a liquid film made of a coating solution;
A second step of heating the liquid film to form a substrate made of a film containing at least a conductive material and polyimide;
A third step of forming a photosensitive layer by applying a coating solution for forming a photosensitive layer containing at least a pigment to the surface of the substrate while maintaining the state where the core and the substrate are integrated;
Including a fourth step of removing the core from the base body,
A method for producing a belt-shaped electrophotographic photosensitive member is provided.
[0018]
As described above, according to the method for producing a belt-shaped electrophotographic photosensitive member of the present invention, a belt-shaped conductive substrate (hereinafter referred to as necessary) that is seamless on the surface of the core is obtained by using the core. (Hereinafter referred to as “seamless substrate belt” or “substrate”), the core body and the seamless substrate belt are kept in an integrated state without separating the core body from the seamless substrate belt. The belt and the photosensitive layer can be formed continuously. Therefore, since the work for separating the core body and the seamless base belt can be omitted, the production efficiency can be improved.
[0019]
Further, since the above work can be omitted, it is possible to sufficiently prevent foreign matters from being mixed into the photosensitive layer during production. Further, since the above work can be omitted, the surface of the predetermined portion where the base of the seamless base belt is to be formed is damaged before the coating solution for forming the photosensitive layer is applied, Unevenness is sufficiently prevented from being formed by bending or the like, and a clean state can be maintained. Since it is easy to uniformly apply a coating solution for forming a photosensitive layer on the surface of such a seamless substrate belt, a photosensitive layer having a uniform thickness can be easily formed on the seamless substrate belt. it can.
[0020]
Further, in the method for producing a belt-shaped electrophotographic photosensitive member of the present invention, in the first step, an annular body provided with a circular hole having an inner diameter larger than the outer diameter of the cross section of the core is used as a coating solution for forming a substrate. It is preferable that the core body is immersed in the coating liquid for forming the substrate through the hole of the annular body, and then the core body is pulled up from the coating liquid.
[0021]
When the above-described operation is performed in the first step, when the core body is pulled up through the hole of the annular body, the coating liquid interposed between the hole of the annular body and the core body causes Friction resistance is generated between the ring body and the ring body can move in the horizontal direction (the surface direction of the liquid surface of the coating liquid) following the movement of the core body. The gap between the core and the core body is adjusted to be constant.
[0022]
Therefore, when pulling up the core, a liquid film made of a coating liquid for forming the core can be easily formed on the core with a uniform thickness.
[0023]
Therefore, if the above-described operation is performed in the first step, a seamless base belt having a uniform thickness can be easily formed on the core. The thickness of the seamless base belt formed on the core takes into consideration the difference between the inner diameter of the hole in the annular body and the outer diameter of the cross section of the core, the composition of the coating liquid for forming the base, and its concentration. Can be easily controlled.
[0024]
Further, in the method for producing a belt-shaped electrophotographic photosensitive member of the present invention, in the third step, when immersed in a coating solution for forming a photosensitive layer on the surface of the core, the coating solution can be contacted. It is preferable that the region is preliminarily subjected to a coating treatment with a coating material for preventing contact with the coating solution, and then the core is immersed in the coating solution. Thereby, a photosensitive layer having a uniform thickness can be more reliably formed.
[0025]
Furthermore, in the method for producing a belt-shaped electrophotographic photoreceptor of the present invention, an undercoat layer disposed between the substrate and the photoreceptor layer may be formed. In this case, after completion of the first step and the second step, an undercoat layer and a photosensitive layer are sequentially formed in the same manner as the third step. That is, the undercoat layer is formed by applying the coating solution for forming the undercoat layer to the surface of the substrate while maintaining the state where the core and the substrate are integrated. Next, a photosensitive layer-forming coating solution containing at least a pigment is applied to the surface of the undercoat layer while the core body, the substrate, and the undercoat layer are kept integrated to form a photosensitive layer. The above fourth step is performed to remove the core from the base.
[0026]
As described above, even when the undercoat layer is formed, the undercoat layer can be formed directly on the seamless substrate belt while the core body and the seamless substrate belt are integrated, and further, the core can be formed. The photosensitive layer can be directly formed on the undercoating layer while the body, the seamless substrate belt and the undercoating layer remain integrated. That is, the seamless base belt, the undercoat layer, and the photosensitive layer can be formed continuously without separating the core from the seamless base belt.
[0027]
Therefore, in this case as well, the production efficiency can be improved, foreign matters can be sufficiently prevented from entering the photosensitive layer during production, and the photosensitive layer having a uniform thickness can be formed on the seamless substrate belt. It can be formed easily.
[0028]
Further, in the method for producing the belt-shaped electrophotographic photosensitive member of the present invention, when the undercoat layer is formed, from the same viewpoint as the viewpoint described above, in the first step, the outer diameter of the cross section of the core body is determined. An annular body having a circular hole having a large inner diameter is floated on the substrate-forming coating solution, the core body is immersed in the substrate-forming coating solution through the hole in the annular body, and then the core body is applied. It is preferable to pull up from the liquid.
[0029]
Further, in the method for producing the belt-shaped electrophotographic photosensitive member of the present invention, when the undercoat layer is formed, the coating for forming the undercoat layer in the surface of the core is also applied from the same viewpoint as described above. A region that can be contacted with the coating solution when immersed in the solution is coated with a coating material for preventing contact with the coating solution, and then the core is immersed in the coating solution. It is preferable.
[0030]
Further, in the method for producing the belt-shaped electrophotographic photosensitive member of the present invention, also when the undercoat layer is formed, the surface of the core body is formed after the formation of the undercoat layer from the same viewpoint as described above. A region that can be contacted with the coating solution when immersed in the coating solution for forming the photosensitive layer is subjected to a coating treatment with a coating material for preventing contact with the coating solution, and then the core is bonded to the core. It is preferable to immerse in a coating solution.
[0031]
Furthermore, the present invention is a belt-shaped electrophotographic photosensitive member having at least a belt-shaped conductive substrate and a photosensitive layer containing a pigment, which is produced by the above-described method for producing a belt-shaped electrophotographic photosensitive member of the present invention. A belt-shaped electrophotographic photosensitive member is provided.
[0032]
Since the belt-shaped electrophotographic photosensitive member of the present invention is manufactured by the above-described method for manufacturing the belt-shaped electrophotographic photosensitive member of the present invention, it has a photosensitive layer having a uniform thickness and has excellent output image quality. Can be obtained.
[0033]
The belt-shaped electrophotographic photosensitive member formed by the method for producing a belt-shaped electrophotographic photosensitive member of the present invention may have a configuration in which a protective layer is disposed on the outer surface of the photosensitive layer, and the photosensitive layer is a so-called single layer. A structure having a mold structure or a so-called stacked structure having a charge generation layer and a charge transport layer may be used.
[0034]
Further, when the belt-like electrophotographic photosensitive member of the present invention is used together with a contact charging type charging means, the volume resistivity of the belt-like conductive substrate is 10. ^Five -10 ^Ten It is preferably Ωcm.
[0035]
Furthermore, the present invention exposes the above-described electrophotographic photosensitive member of the present invention, charging means for charging the electrophotographic photosensitive member, and the electrophotographic photosensitive member charged by the charging means to form an electrostatic latent image. An image forming apparatus comprising: an exposure unit; a developing unit that develops an electrostatic latent image with toner to form a toner image; and a transfer unit that transfers the toner image to a transfer medium.
[0036]
Since the image forming apparatus of the present invention includes the above-described belt-shaped electrophotographic photosensitive member of the present invention, an excellent output image quality can be obtained.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.
[0038]
Hereinafter, a belt-like electrophotographic photosensitive member having a configuration including at least a seamless base belt (a seamless belt-like conductive base) and a photosensitive layer at least containing a pigment and disposed on the outer surface of the base. A preferred embodiment of the manufacturing method will be described.
[0039]
In this manufacturing method, a coating liquid for forming a substrate is mainly applied to the surface of a predetermined portion where a seamless base belt of the core is to be formed, and a liquid film is formed from the coating liquid for forming the substrate on the surface of the core. (Hereinafter, referred to as “coating film 4”), a second step of heating the liquid film to form a substrate made of a film containing at least a conductive material and polyimide, A third step of forming a photosensitive layer by applying a coating solution for forming a photosensitive layer on the surface of the seamless substrate belt while maintaining the state where the seamless substrate belt is integrated, and removing the core from the seamless substrate belt It is comprised from the 4th process.
[0040]
First, the first step will be described.
FIG. 1 is a schematic cross-sectional view showing an example of a basic configuration of a dip coating apparatus for performing the first step in the present invention. FIG. 2 is a front view of the dip coating apparatus shown in FIG. 1 viewed from a direction parallel to the central axis of the core. However, in FIG.1 and FIG.2, only the principal part of the apparatus at the time of performing a 1st process was shown, and the other component was abbreviate | omitted.
[0041]
As shown in FIGS. 1 and 2, the dip coating apparatus 100 for performing the first step mainly includes a coating tank 3 that contains a coating solution 2 for forming a substrate including at least a conductive material and a PI precursor. The seamless base belt 10 formed from the coating solution 2 in a series of steps until the annular body 5 floated on the surface of the coating solution 2 in the coating tank 3 and at least the photosensitive layer 15 (see FIG. 4 described later) are obtained. The core body 1 is a support body for a seamless belt-like conductive substrate (see FIG. 3 to be described later), and holding means (not shown) that detachably holds the core body 1.
[0042]
The core body 1 has a columnar or cylindrical shape. The constituent material of the core body 1 is preferably aluminum or zinc from the viewpoint that the coefficient of thermal expansion is large. Also, the surface of the core body 1 is plated with chromium or nickel, covered with a fluororesin or silicone resin, or the seamless base belt 10 obtained in the second step described later is not firmly bonded to the surface of the core body 1. Alternatively, a release agent may be applied.
[0043]
Further, when the coating film 4 is dried in the second step to be described later to obtain a PI precursor film (not shown), the residual solvent in the coating film 4 cannot be completely removed, or the PI precursor in the second step. If the water generated from the PI precursor film cannot be removed when the body film is heated to obtain the seamless base belt 10, it may be unavoidable that the seamless base belt 10 is swollen. This is particularly noticeable when the thickness of the seamless base belt 10 is thicker than 50 μm.
[0044]
When the above inconvenience may occur, the surface of the core body 1 may be roughened to Ra (center line average roughness defined in JIS B0601) of about 0.2 to 2 μm. It is valid. Thereby, the residual solvent generated from the coating film 4 or the water vapor generated from the PI precursor film can exit to the outside through a slight gap formed between the core 1 and the coating film 4 or the PI precursor film. Further, the seamless base belt 10 can be prevented from swelling. For roughening the surface of the core body 1, there are methods such as blasting, cutting, and sandpaper.
[0045]
The annular body 5 is a continuous annular body provided with a circular hole 6 having an inner diameter larger than the outer diameter of the cross section of the core body 1. The annular body 5 has the shape and the holes 6 described above, is composed of a constituent material that is not corroded by the coating liquid 2, and has a structure that floats in the coating liquid 2. Is not particularly limited. For example, metal, plastic, etc. may be used as the constituent material. Further, for example, a hollow structure may be used.
[0046]
Further, a rod-shaped positioning auxiliary member (not shown) may be provided from the outer peripheral surface of the annular body 5 toward the inner wall surface of the coating tank 2. Accordingly, when the annular body 5 is floated on the coating liquid 2, the annular body 5 is easily positioned at the center of the liquid surface of the coating liquid 2 accommodated in the coating tank 3, and the work of the first step proceeds. Becomes easier. The positioning auxiliary member may be fixed at one end to the outer peripheral surface of the annular body 5 or the inner wall surface of the coating tank 2 and free at the other end, and fixed at one end to the outer peripheral surface of the annular body 5. The other end may be fixed to the inner wall surface of the coating tank 2. Further, in order to prevent the annular body 5 from sinking, an auxiliary member (for example, a net) for preventing the annular body 5 from sinking beyond a predetermined depth from the liquid surface of the coating liquid 2 is provided from the liquid surface of the coating liquid 2. You may provide in the inner wall face of the coating tank 2 of predetermined depth.
[0047]
Further, the annular body 5 only needs to be arranged in a state where it can freely move in the vicinity of the liquid surface of the coating liquid 2 and is disposed in a state where the annular body 5 is suspended in the liquid surface state of the coating liquid 2 as described above. In addition to the method of making it, you may employ | adopt the method of supporting the annular body 5 with a roll or a bearing, the method of supporting the annular body 5 with an air pressure, etc.
[0048]
The shape of the hole 6 provided in the annular body 5 is such that the area of the opening on the lowermost side in contact with the liquid surface of the coating solution 2 is large and the area of the opening on the uppermost side facing the lowermost part is small. It preferably has a shape. Thereby, when pulling up the core body 1, the coating film 4 of the coating liquid 2 can be smoothly formed on the outer surface (outer surface) of the core body 1. In this case, the shape of the hole 6 only needs to satisfy the conditions of the size of the opening on the lowermost side and the opening on the uppermost side. The shape may be substantially trapezoidal, or only the lowermost opening may have a narrow step shape or a curved shape.
[0049]
The inner diameter of the hole 6 is set in consideration of the gap d16 formed between the hole 6 and the core body 1 in consideration of the outer diameter of the core body 1 to be used. Further, the thickness of the obtained seamless base belt 10 is determined in consideration of the thickness of the coating film 4 made of the coating liquid 2 formed through the gap d16 and the non-volatile content concentration in the coating liquid 2. . The gap d16 formed between the hole 6 and the core body 1 is preferably 1 to 2 times the thickness of the coating film 4. The reason why the thickness is 1 to 2 times is that the gap d16 and the thickness of the coating film 4 are not always equal due to the viscosity or surface tension of the coating liquid 2.
[0050]
Further, the holding means for the core body 1 moves the core body 1 up and down in a direction in which the central axis of the core body 1 is substantially parallel to the normal direction of the liquid surface of the coating liquid 2 while holding the core body 1. A lift mechanism (not shown) is provided. By the lift mechanism of the holding means, the core body 1 can be immersed in the coating solution 2 or pulled up from the coating solution 2.
[0051]
The coating liquid 2 is not particularly limited as long as it is a liquid containing at least a conductive material and a PI precursor. From the viewpoint of more smoothly forming the coating film 4 made of the coating liquid 2 on the core body 1, its solid content The concentration is preferably 10 to 40% by mass, and the viscosity is preferably 10 to 1000 Pa · s. In particular, when the viscosity of the coating liquid 2 exceeds 1000 Pa · s, the tendency of the core body 1 to be difficult to lift from the coating liquid 2 increases. In addition, when the core body 1 is pulled up from the coating solution 2, the tendency that it is difficult to form the coating film 4 having a predetermined thickness on the core body 1 is increased.
[0052]
Examples of the conductive material contained in the coating liquid 2 include carbon black, carbon beads granulated from carbon black, carbon fibers, carbon-based materials such as graphite, metals or alloys such as copper, silver, and aluminum, tin oxide, Indium oxide, antimony oxide, SnO ₂ -In ₂ O _Three And composite oxides such as conductive titanium oxide. A conductive material is added. The volume resistivity of the seamless base belt 10 finally obtained is 10 ⁰ -10 ^Ten The amount is preferably about Ωcm, and the blending amount of the conductive material is adjusted so as to have this volume resistivity value.
[0053]
As described above, when the belt-shaped electrophotographic photoreceptor 20 is used together with a contact charging type charging means, the volume resistivity of the seamless substrate belt 10 (a seamless belt-shaped conductive substrate) is low. 10 ^Five -10 ^Ten It is preferably Ωcm. The volume resistivity of the seamless base belt 10 is 10 ^Five -10 ^Ten By setting the resistance to Ωcm, it is possible to more reliably prevent the occurrence of discharge breakdown when the belt-shaped electrophotographic photosensitive member 20 is charged by the contact charging method.
[0054]
As described above, discharge breakdown occurs due to local concentration of charging current, but the volume resistivity of the seamless base belt 10 is 10%. ^Five -10 ^Ten By setting the resistance to Ωcm, the current during charging has an appropriate spread on the surface of the seamless base belt 10 and the current concentration is eliminated. Volume resistivity is 10 ^Ten If it exceeds Ωcm, the electric charge cannot be completely discharged inside the seamless base belt 10 and a residual potential may be generated. When used with a charging means employing a contact charging method, the volume resistivity of the seamless base belt 10 is 10 ^Five If it is less than Ωcm, the above-described problem of current concentration tends to occur, which may cause discharge breakdown. When used with a charging means employing a corona charging method, the above-described problem of current concentration hardly occurs, so the volume resistivity is 10 ^Five It may be less than Ωcm.
[0055]
In the present invention, the PI is preferably at least one of PIs composed of repeating units represented by the following formulas (1) to (10). Moreover, PI obtained by selecting and combining two or more repeating units from the repeating units of the following formulas (1) to (10) may be used. For example, PI having both repeating units of the following formula (1) and the following formula (2) may be used, and PI having both repeating units of the following formula (5) and the following formula (6) may be used. Therefore, as the PI precursor to be contained in the coating liquid 2, a precursor capable of forming these PIs is preferable.
[0056]
[Chemical 1]

[0057]
[Chemical 2]

Here, in Formula (2), “R” represents an alkyl group.
[0058]
[Chemical 3]

[0059]
[Formula 4]

[0060]
[Chemical formula 5]

[0061]
[Chemical 6]

[0062]
[Chemical 7]

[0063]
[Chemical 8]

[0064]
[Chemical 9]

[0065]
[Chemical Formula 10]

Here, in formula (10), “R” represents an alkylene group.
[0066]
In the first step, as shown in FIGS. 1 and 2, the annular body 5 is floated on the coating liquid 2, the core body 1 is immersed in the coating liquid 2 through the hole 6 of the annular body 5, The core body 1 is pulled up from the coating solution 2. From the viewpoint of more smoothly forming the coating film 4 made of the coating solution 2 on the core body 1, the pulling speed is about 0.1 to 2 m / min when expressed in terms of the length in the longitudinal direction of the core body 1. Is preferred.
[0067]
Here, when the core body 1 is pulled up through the hole 6 of the annular body 5, the coating liquid 2 interposed between the hole 6 of the annular body 5 and the core body causes friction between the core body 1 and the annular body 5. Resistance occurs and the annular body 5 is lifted slightly. When the annular body 5 is lifted, the annular body 5 moves in the horizontal direction (surface direction of the liquid surface of the coating liquid) so that the frictional resistance with the core body is constant in the circumferential direction of the hole 6. And the gap d16 between the core body 1 and the core body 1 are adjusted to be constant. For example, when the gap d16 changes when the core body 1 is pulled up, an unbalanced state occurs in which the frictional resistance increases in a certain gap d16 and the frictional resistance decreases in the opposite gap d16. .
[0068]
However, in this case as well, the annular body 5 moves in the horizontal direction so that the frictional resistance with the core body 1 is constant in the circumferential direction of the hole 6, so that the gap d16 having a large frictional resistance is widened. The annular body 5 moves in the horizontal direction so that the portion of the gap d16 having a small frictional resistance is narrowed, and the gap between the annular body 5 and the core body 1 is constant. That is, when the core body 1 is pulled up through the hole 6 of the annular body 5, the annular body 5 does not contact the core body 1, and the hole 6 of the annular body 5 and the core body 1 always have a constant gap. Is preserved.
[0069]
Therefore, even if the core body 1 is in a state where the central axis and the normal direction of the liquid surface of the coating liquid 2 are not parallel to each other and are slightly inclined or vibrated, the annular body 5 is Since the body 1 can follow the movement of the body 1 and move in the horizontal direction (surface direction of the liquid surface of the coating liquid), the liquid film 4 (hereinafter referred to as the coating film 4) made of the coating liquid 2 is uniformly formed on the core body 1. Can be easily formed with a small thickness.
Therefore, if the above-described operation is performed in the first step, the seamless base belt 10 having a uniform thickness can be easily formed on the core body 1.
[0070]
Next, the second step will be described.
In the second step, first, the liquid coating film 4 made of the coating liquid 2 attached to the surface of the core body 1 is dried, and a solid PI precursor film (at least including a conductive material and a PI precursor ( (Not shown).
[0071]
Here, the temperature condition during drying is preferably 50 to 120 ° C., and the drying time is preferably 30 to 200 minutes. In addition, when an aprotic polar solvent is used as the solvent used for the coating solution 2, the drying of the coating film 4 becomes extremely slow, so that the coating film 4 or the PI precursor film obtained from the coating film 4 itself is dried during the drying. Under the influence of the gravity, so-called “dripping” is likely to occur. In this case, it is preferable to dry the coated core body 1 while rotating at a rotational speed of about 10 to 60 rpm so that the longitudinal direction thereof is horizontal (a direction perpendicular to the direction in which gravity is applied). .
[0072]
Next, the PI precursor film obtained is heated to cause the condensation reaction of the PI precursor to proceed, and the seamless base belt 10 made of a film containing at least a conductive material and PI is formed.
[0073]
Here, the heating temperature condition is preferably a temperature of 300 to 450 ° C. The heating time is preferably 20 to 60 minutes. As described above, when the PI precursor film is heated to advance the condensation reaction of the PI precursor, the seamless base belt 10 is formed. At that time, as described above, if the solvent remains in the PI precursor film or the seamless base belt 10, the seamless base belt 10 may be swollen. Therefore, the solvent can be completely removed. preferable. In addition, from the viewpoint of more reliably preventing the occurrence of the swelling of the seamless base belt 10, the temperature is not increased rapidly during heating, but gradually increased or slowly increased at an appropriate constant heating rate. It is preferable to make it.
[0074]
The thickness of the seamless base belt 10 is preferably 40 to 100 μm when the belt-shaped electrophotographic photosensitive member 20 obtained in the fourth step described later is bent and used, and the belt-shaped electrophotographic photosensitive member is preferable. When 20 is used in a state where it is fitted to a cylindrical base, it is preferably about 20 to 50 μm. In consideration of the thickness of the belt-shaped electrophotographic photosensitive member 20, the thickness of the liquid coating film 4 made of the coating liquid 2 adhered to the surface of the core 1 is adjusted. Specifically, for example, the viscosity of the coating liquid 2 and the composition of the composition component in the first step described above, the adjustment of the size of the gap d16 between the core body 1 and the annular body 5, For example, the number of coatings of the coating liquid 2 may be adjusted by repeating the process.
[0075]
Next, the third step will be described.
In the third step, a photosensitive layer is formed by coating a coating solution for forming a photosensitive layer containing at least a pigment on the surface of the seamless substrate belt while maintaining the core 1 and the seamless substrate belt 10 in an integrated state. It is a process.
[0076]
FIG. 3 is a schematic cross-sectional view showing an example of a basic configuration of a dip coating apparatus for performing the third step according to the present invention. FIG. 4 is a schematic cross-sectional view showing the basic configuration of a preferred embodiment of the belt-shaped electrophotographic photosensitive member of the present invention. However, FIG. 3 shows only the main part of the apparatus when performing the third step, and other components are omitted.
[0077]
As shown in FIG. 3, a dip coating apparatus 200 for performing the third step mainly includes a coating tank 13 for storing a coating solution 12 for forming a photosensitive layer containing at least a pigment, and the seamless obtained in the third step. It is comprised from the core 1 in which the base belt 10 was formed, and the holding means (not shown) which hold | maintains the core 1 so that removal is possible.
Further, the holding means for the core body 1 holds the core body 1 and holds the core body 1 with respect to the normal direction of the liquid surface of the coating liquid 12 in the same manner as the holding means for the dip coating apparatus described in the first step. Is provided with a lift mechanism (not shown) capable of moving the core body 1 up and down in a direction in which the central axis of the main body 1 is substantially parallel. The lift mechanism of the holding means enables the core body 1 to be immersed in the coating liquid 12 or pulled up from the coating liquid 2.
[0078]
Further, the dip coating apparatus 200 may be configured to store the coating solution 12 in the coating tank 13, but may be configured to supply from the lower part of the coating tank 13, overflow and collect from the upper part, and circulate with a pump. . In that case, it is effective to add a filter, a viscometer, a diluting liquid adding device and the like to the circulation path.
[0079]
Here, when the core body 1 is immersed in the coating liquid 12, if there is an exposed area where the seamless base belt 10 is not formed in close contact with the surface portion of the core body 1, the coating liquid 12 adheres to that area. For example, when a part of the seamless base belt 10 is peeled off and there is a gap between the seamless base belt 10 and the core body 1, the coating liquid 12 enters the gap, and the seamless process is performed in the fourth step described later. There arises a problem that the base belt 10 cannot be removed from the core body 1 or the core body 1 cannot be reused.
[0080]
Therefore, in this third step, the region of the surface of the core body 1 that can be brought into contact with the coating solution 12 when immersed in the coating solution 12 for forming the photosensitive layer is formed with the coating solution 12. It is preferable to perform a coating treatment with the coating material 11 for preventing contact, and then immerse the core body 1 in the coating solution 12.
[0081]
In particular, when there is an exposed region where the seamless base belt 10 is not formed in close contact with the surface portion on the side that becomes the lower end of the core body 1 integrated with the seamless base belt 10, the above problem occurs remarkably. As shown in FIG. 3, it is preferable to coat the surface portion on the side which becomes the lower end of the core body 1 with a covering material 11. Examples of the covering material 11 include an adhesive tape. By winding the adhesive tape around the surface portion on the side that becomes the lower end of the core body 1, the surface portion can be covered and contact between the surface of the core body 1 and the coating liquid 12 can be sufficiently prevented.
[0082]
As another covering method using the covering material 11, for example, a wide rubber band is used as the covering material 11, and this is extended and expanded, and the portion to be covered of the core body 1 integrated with the seamless base belt 10 (for example, A method of covering the surface portion on the lower end side of the core body 1, a method of attaching a cap (for example, a rubber cap) having a shape covering the entire surface portion on the lower end side of the core body 1, and the like. It is done.
Thereby, the photosensitive layer 15 having a uniform thickness can be more reliably formed.
[0083]
Further, as shown in FIG. 3, in the third step, after the core body 1 integrated with the seamless base belt 10 is immersed in the coating liquid 12, the core body 1 is pulled up so that the surface of the seamless base belt 10 is formed. Then, a liquid film 14 (hereinafter referred to as “coating film 14”) made of the coating liquid 12 is formed. The pulling speed of the core 1 at this time is preferably 50 to 500 mm / min, although it depends on the thickness of the photosensitive layer 15 to be formed.
[0084]
After pulling up, the coating layer 14 is dried and the solvent is removed from the coating layer 14 to form the photosensitive layer 15. Here, the previously formed coating material 11 is removed before or after drying. Further, when the dip coating operation is repeated a plurality of times, the covering material 11 may not be removed for each dip coating, but may be removed after drying or drying after finishing the last dip coating operation.
[0085]
The configuration of the photosensitive layer 15 may be a so-called single layer type or a so-called laminated type including a charge generation layer and a charge transport layer. Accordingly, the component composition of the coating solution 12 is also determined in accordance with the configuration of the photosensitive layer 15 to be formed. For example, in the case of a single layer type, only one type of coating solution 12 may be prepared, but in the case of a laminated type, two types of coating solutions 12 that are respectively adapted to the configuration of the charge generation layer and the configuration of the charge transport layer. The dip coating and drying operations must be performed at least once to form each layer.
[0086]
The single-layer type photosensitive layer that determines the composition of the coating solution 12 includes those in which a charge generating pigment is mainly dispersed in a resin and those in which a charge generating pigment is dispersed in a charge transport layer.
[0087]
The charge generation layer of the laminated photosensitive layer that determines the configuration of the coating solution 12 includes a layer containing a pigment such as phthalocyanine that absorbs light and generates a charge, and a binder such as polyvinyl butyral resin. The thickness is preferably 0.01 to 1 μm. Examples of the charge transport layer include a layer containing a charge transport material such as a hydrazone compound, a stilbene compound, a benzidine compound, a butadiene compound, and a triphenylamine compound, and a binder resin such as polycarbonate. Usually, it is preferable that it is 15-40 micrometers.
[0088]
Next, the fourth step will be described. The fourth step is a step of removing the core body 1 from the seamless base belt 10. Thereby, the belt-shaped electrophotographic photosensitive member 20 can be obtained.
[0089]
In addition, after the completion of the fourth step, if necessary, cutting processing for aligning the length of the end portion of the belt-shaped electrophotographic photosensitive member 20, electrode mounting processing, position guide member mounting processing, characteristic inspection, etc. May be applied.
[0090]
Next, an example of a method for using the belt-shaped electrophotographic photosensitive member of the present invention will be described using the belt-shaped electrophotographic photosensitive member 20 as an example.
[0091]
The belt-shaped electrophotographic photosensitive member 20 may be used by being laid on a plurality of rolls, or may be used by being fitted on the outer peripheral surface of a cylindrical substrate. In the case where the belt-like electrophotographic photosensitive member 20 is fitted to the cylindrical substrate, an adhesive or an adhesive tape may be used as a method for fitting the belt-shaped electrophotographic photosensitive member 20 to the cylindrical substrate, but the cylindrical substrate is cooled to shrink its volume. And a method of fitting the belt-like electrophotographic photosensitive member therewith is preferable. When the cylindrical substrate is returned to room temperature, the volume expands and the belt-like electrophotographic photosensitive member is fixed to the outer peripheral surface of the cylindrical substrate with a strong frictional force. Even in such a case, since the PI resin has high tensile strength, there is an advantage that it is difficult to tear.
[0092]
Examples of the cylindrical substrate for this application include metal cylinders such as aluminum and stainless steel, and plastic cylinders such as phenol resin and polyacetal resin. Here, the outer diameter of the cylindrical substrate may be a value that is slightly larger than the inner diameter of the belt-shaped electrophotographic photosensitive member 20 at room temperature and smaller than the inner diameter of the belt-shaped electrophotographic photosensitive member 20 when cooled. Moreover, although it depends on the thermal expansion coefficient of the constituent material of the cylindrical base, the cooling temperature at the time of fitting is preferably −200 to −20 ° C. As a cooling method at the time of fitting, a method in which the cylindrical substrate is immersed in a liquid state refrigerant of −70 ° C. or lower typified by liquid nitrogen (about −196 ° C.) or liquid air (about −190 ° C.) is preferable. .
[0093]
When the belt-shaped electrophotographic photosensitive member 20 is used by being fitted to a cylindrical substrate, for example, when the belt-shaped electrophotographic photosensitive member 20 has reached the end of its life, the cylindrical substrate is cooled again, so that the used belt-shaped electrophotographic photosensitive member 20 is re-cooled. The electrophotographic photosensitive member 20 can be easily detached from the cylindrical substrate. If the new belt-shaped electrophotographic photosensitive member 20 is fitted again while the cylindrical substrate is cooled, the replacement operation can be performed very easily. This also makes it possible to easily reuse a cylindrical substrate that has been conventionally discarded and difficult to reuse because it takes time to remove the photosensitive layer.
[0094]
When the belt-like electrophotographic photosensitive member 20 is used, when the contact charging method in which a conductive roll or brush to which a voltage is applied is brought into contact is employed, the volume resistivity of the conductive substrate is as described above. 10 ^Five -10 ^Ten If it is set to Ωcm, the photoreceptor 20 can be charged without causing discharge breakdown. When the belt-shaped electrophotographic photosensitive member 20 is used while being laid on a plurality of rolls, it is preferable to arrange the rolls at the position of the contact charger.
[0095]
The image forming apparatus of the present invention is an apparatus equipped with the electrophotographic photosensitive member of the present invention, and an excellent output image quality can be obtained by mounting the photosensitive member. In addition to the electrophotographic photosensitive member of the present invention, the image forming apparatus of the present invention exposes the charging means for charging the electrophotographic photosensitive member and the electrophotographic photosensitive member charged by the charging means to form an electrostatic latent image. If the image forming apparatus has a configuration including an exposure unit for developing, a developing unit for developing the electrostatic latent image with toner to form a toner image, and a transfer unit for transferring the toner image to a transfer medium, the other configuration Is not particularly limited.
[0096]
The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment.
[0097]
For example, in the above embodiment, a protective layer may be further provided. In this case, after completion of the third step, a separately prepared coating solution for forming a protective layer is applied to the surface of the photosensitive layer 15 in which the core 1, the seamless base belt 10 and the photosensitive layer 15 are integrated. Here, in this case, it is preferable to form the protective layer in the same procedure as in the third step, except that the coating liquid for forming the protective layer is used instead of the coating liquid 12 for forming the photosensitive layer 15.
[0098]
In the above embodiment, an undercoat layer may be further provided. In this case, after completion of the second step, a separately prepared coating solution for forming the undercoat layer is applied to the surface of the seamless base belt 10 in which the core 1 and the seamless base belt 10 are integrated. Here, in this case, the undercoat layer may be formed in the same procedure as in the third step, except that the undercoat layer forming coating solution is used instead of the photosensitive layer 15 forming solution 12. preferable. When forming the photosensitive layer after forming the undercoat layer, it is preferable to form the photosensitive layer in the same procedure as in the third step except that the photosensitive layer is formed on the surface of the undercoat layer. .
[0099]
When the undercoat layer is provided, the thickness is usually 0.1 to 5 μm. However, in order to prevent discharge breakdown of the photosensitive layer, the thickness may be increased to 5 to 30 μm by dispersing powder in the layer. is there. The powder used for this includes metal oxides such as titanium oxide, zinc oxide, tin oxide, aluminum oxide, zirconium oxide and cerium oxide, and other powders may be used in combination. In addition, the resin contained in the undercoat layer includes alcohol-soluble nylons such as type 8 nylon and copolymer nylon, conductive polymers such as quaternary ammonium salts, casein, polyurethane, polyester, polyvinyl alcohol, polyvinyl butyral, and polyvinyl acetal. Etc.
When the undercoat layer is provided, the volume resistivity of the conductive substrate is 10 together with the undercoat layer. ^Five -10 ^Ten If it is set to Ωcm, it is convenient for contact charging.
[0100]
In addition, the first step of the present invention is not limited to the first step of the above-described embodiment. For example, the first step may be performed using the following apparatus. FIG. 5 is a schematic cross-sectional view showing another example of the basic configuration of the dip coating apparatus for performing the first step according to the present invention shown in FIG. The dip coating apparatus 100A shown in FIG. 5 has the same configuration as the dip coating apparatus 100 shown in FIG. 1 except that an annular coating tank 7 is provided instead of the coating tank 3 shown in FIG. .
[0101]
A circular opening 71 having an inner diameter larger than the outer diameter of the core body 1 to be used is formed at the center of the bottom of the annular coating tank 7. Further, a sealing material 8 (for example, rubber packing) made of an annular body having a circular opening 81 having an inner diameter equal to or smaller than the outer diameter of the core 1 to be used is formed on the outer surface of the bottom of the annular coating tank 7. Etc.) are arranged. The sealing material 8 is a member for preventing the coating liquid 2 from leaking outside from the opening 71 of the annular coating tank 7.
[0102]
In the first step, the core body 1 is inserted into the annular coating tank 7 from the opening 71. Thereafter, the coating liquid 2 is filled into the annular coating tank 7 from the upper opening. At this time, since the sealing material 8 is disposed at the bottom of the annular coating tank 7, the coating liquid 2 is prevented from leaking outside. The base body 1 is sequentially lifted from the lower part to the upper part of the annular coating tank through the hole, and passes through the hole 6 of the annular body 5 floating on the liquid surface of the coating liquid 12, thereby forming the coating film 4 on the surface. Is done.
[0103]
Here, as shown in FIG. 5, a cylindrical lid member 9 having substantially the same outer diameter as the core body 1 and having a predetermined length in the longitudinal direction may be attached to the upper or lower portion of the core body 1. Good. Thereby, even if the core body 1 is pulled up onto the liquid surface of the coating liquid 2, it is possible to prevent the coating liquid 2 from leaking outside through the opening 71 of the annular coating tank 7.
The method using the annular coating tank 7 shown in FIG. 5 has an advantage that the volume of the annular coating tank 7 can be made significantly smaller than the volume of the coating tank 3 shown in FIG.
[0104]
【Example】
EXAMPLES Hereinafter, although an Example is given and the content of this invention is demonstrated in more detail, this invention is not limited to these Examples at all.
[0105]
Belt-shaped electrophotographic photoreceptors of Examples 1 to 4 were prepared according to the following procedure.
[0106]
Example 1
A coating liquid containing a PI precursor (trade name: U varnish S, manufactured by Ube Industries, concentration: 18% by mass, viscosity: about 5 Pa · s) was prepared. Carbon black (trade name: Conductex 975, manufactured by Colombian Carbon Co., Ltd.) is mixed with this solution (coating solution) so as to be 18% by mass with respect to the solid components of the solution, and then dispersed by a ball mill for 24 hours. A coating solution for forming a belt was prepared (hereinafter referred to as “coating solution 22”).
[0107]
On the other hand, an aluminum cylinder is prepared, and the surface is roughened to Ra 0.8 μm by blasting with spherical alumina, and then a silicone mold release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the surface. It was applied and baked at 300 ° C. for 1 hour to obtain a core body having an outer diameter of 68 mm and a length of 400 mm.
[0108]
As an annular body having the same shape as the annular body 5 shown in FIG. 2, an aluminum annular body having an outer diameter of 80 mm and an uppermost inner diameter of 69.2 mm was prepared. An annular coating tank (inner diameter: 100 mm, height: 50 mm, inner diameter of bottom opening: 70 mm) having the same configuration as the annular coating tank 7 shown in FIG. 5 was prepared. Further, a soft polyethylene sealing material having a thickness of 0.5 mm and an opening having an inner diameter of 67 mm was attached to the bottom surface of the annular coating tank.
[0109]
Next, a core member made of a cylindrical polyether resin having an outer diameter of 68 mm and a length of 60 mm is attached to one end of the core body, and the lid member is attached from the opening side at the bottom of the annular coating tank. Inserted. At this time, the core was inserted from the end side where the lid member was not attached. At this time, the core was previously placed in the annular coating tank, and the core was inserted into the hole of the ring.
[0110]
Thereafter, the coating liquid 22 is put into the annular coating tank, and the rising speed is adjusted to 0.9 to 0.7 m / min so that the rising height of the annular body from the liquid surface of the coating liquid 22 is about 5 mm. The core body 1 was pulled up and the coating liquid 22 was applied. At that time, the annular body 5 did not come into contact with the core body.
[0111]
After the coating liquid 22 was applied, a liquid film containing a PI precursor having a thickness of about 600 μm was formed on the core. Next, the core body is dried at 130 ° C. for 60 minutes while being tilted in the horizontal direction (direction in which the direction of the central axis is perpendicular to the pulling direction) and rotated at 20 rpm, and then at 200 ° C. for 30 minutes, 350 Heat at 30 ° C. for 30 minutes. As a result, a seamless base belt made of a film containing a PI resin having a thickness of 75 μm was formed. The volume resistivity of this seamless substrate belt is about 10 ^Five It was Ωcm.
[0112]
Here, the seamless base belt contracted, and exposed portions having a width of about 8 mm were generated at both ends of the core. Without removing the seamless substrate belt from the core body, a polyester tape having a width of 20 mm (trade name: No. 31B) is applied to the exposed portion which becomes the lower end side of the seamless substrate belt when dipped in the coating solution for forming the undercoat layer. , Manufactured by Nitto Denko Co., Ltd.) was wrapped around the end of the core body, and the exposed portion of the core body and the end portion of the seamless base belt near the exposed portion were covered.
[0113]
Next, 5 parts by mass of 8 nylon (Rakkamide, manufactured by Dainippon Ink and Chemicals) is dissolved in a mixed solvent of 40 parts by mass of methanol and 60 parts by mass of 1-butanol, and a coating solution for forming an undercoat layer (hereinafter referred to as “coating solution”). 23 "). This coating solution is put in a coating tank (inner diameter: 90 mm, depth: 450 mm) having the same shape as the coating tank 13 shown in FIG. By pulling up at a rate of 2 m / min, a liquid film composed of the coating solution 23 was formed on the seamless substrate belt. Thereafter, drying was performed at 135 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.8 μm on the seamless substrate belt.
[0114]
Next, 1 part by mass of polyvinyl butyral resin (trade name: ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 19 parts by mass of cyclohexanone, and 3 parts by mass of chlorogallium phthalocyanine was added thereto and dispersed by a sand mill. 20 parts by mass of 2-butanone was further added to the obtained dispersion to prepare a coating solution for forming a charge generation layer. A charge generation layer having a thickness of 0.1 μm was formed on the undercoat layer by the same procedure as the above undercoat layer except that the core body in which the undercoat layer and the seamless base belt were integrated was immersed in this liquid. .
[0115]
Subsequently, 40 parts by mass of N, N′-diphenyl-N, N ′-(m-tolyl) benzidine as a charge transfer agent and a polycarbonate Z resin having a weight average molecular weight of 40,000 (trade name: Iupilon, Mitsubishi Gas Chemical Company, Inc.) 60 parts by mass was dissolved in 250 parts of dioxane to prepare a coating solution for forming a charge transport layer. A core body in which the undercoat layer, the seamless base belt and the charge generation layer are integrated is immersed in this liquid, followed by heating and drying at 135 ° C. for 40 minutes to form a charge transport layer having a thickness of 23 μm on the charge generation layer. Formed.
[0116]
By these operations, a belt-shaped electrophotographic photosensitive member could be obtained. The obtained photosensitive member was cut off at irregular portions at both ends to form a belt having a width of 315 mm and stretched between two 10 mmφ rolls.
[0117]
Next, this belt-shaped electrophotographic photosensitive member was mounted on a full-color printer (trade name: Docu Print C2220, manufactured by Fuji Xerox Co., Ltd.), and an electrophotographic characteristic evaluation test was performed by a print test. As a charging method at that time, a voltage obtained by superimposing an alternating voltage of 1.8 kV 2 kHz on -350 V DC was applied to a charging roll, and the photosensitive member was charged by contacting the belt-like electrophotographic photosensitive member. The surface potential Vh of the belt-shaped electrophotographic photosensitive member during charging was set to be Vh = −350V. Next, the belt-shaped electrophotographic photosensitive member was exposed and developed with a one-component toner. The amount of light at the time of exposure was adjusted so that the surface potential Vl of the belt-shaped electrophotographic photosensitive member after discharge by light irradiation was Vl = -60V. This series of operations was repeated to create 10,000 images, but no black spots due to abnormal discharge (leakage) were observed.
[0118]
(Example 2)
An aluminum cylinder was prepared and subjected to the same blasting treatment and release agent treatment as in Example 1 to produce a core body having an outer diameter of 30 mm and a length of 400 mm. As an annular body having the same shape as the annular body 5 shown in FIG. 2, an aluminum annular body having an outer diameter of 50 mm and an uppermost inner diameter of 30.6 mm was prepared. Further, an annular coating tank (inner diameter: 80 mm, height: 50 mm, inner diameter of the bottom opening: 32 mm) having the same configuration as the annular coating tank 7 shown in FIG. 5 was prepared. Further, a soft polyethylene sealing material having a thickness of 0.5 mm and an opening having an inner diameter of 28 mm was attached to the bottom surface of the annular coating tank.
[0119]
Next, a lid member made of a cylindrical polyether resin having an outer diameter of 30 mm and a length of 40 mm is attached to one end of the core body. Further, in the same manner as in Example 1, from the opening side at the bottom of the annular coating tank. The core body to which the lid member was attached was inserted. At this time, the core was inserted from the end side where the lid member was not attached.
[0120]
Thereafter, the same coating liquid 22 as that used in Example 1 was put in the annular coating tank, and the rising speed was adjusted to 0.9 to be about 5 mm from the liquid surface of the coating liquid 22. The core body 1 was pulled up while being adjusted to 0.7 m / min, and the coating liquid 22 was applied. At that time, the annular body 5 did not come into contact with the core body.
[0121]
After the coating liquid 22 was applied, a liquid film containing a PI precursor having a thickness of about 300 μm was formed on the core. Next, the core body is dried at 130 ° C. for 60 minutes while being tilted in the horizontal direction (direction in which the direction of the central axis is perpendicular to the pulling direction) and rotated at 20 rpm, and then at 200 ° C. for 30 minutes, 350 Heat at 30 ° C. for 30 minutes. As a result, a seamless base belt made of a film containing PI resin having a thickness of 40 μm was formed. The volume resistance of this seamless substrate belt is about 10 ^Five It was Ωcm.
[0122]
Here, the seamless base belt contracted, and exposed portions having a width of about 7 mm were formed at both ends of the core. Without removing the seamless substrate belt from the core body, a polyester tape having a width of 20 mm (trade name: No. 31B) is applied to the exposed portion which becomes the lower end side of the seamless substrate belt when dipped in the coating solution for forming the undercoat layer. Nitto Denko) was wound around the end of the core body, and the exposed portion of the core body and the end portion of the seamless base belt near the exposed portion were covered.
[0123]
Next, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed by the same procedure as in Example 1, and both ends were cut off to obtain a belt-shaped electrophotographic photosensitive member having a width of 320 mm.
[0124]
In addition, an aluminum cylindrical substrate having an outer diameter of 30.04 mm and a length of 330 mm was separately prepared. When this was immersed in liquid nitrogen and cooled, the outer diameter contracted to about 29.92 mm. In this state, the belt-shaped electrophotographic photosensitive member was quickly fitted on the outer periphery of the cylindrical substrate. When the temperature was returned to room temperature, the belt-shaped electrophotographic photosensitive member was fixed by the expansion of the cylindrical substrate.
[0125]
The belt-shaped electrophotographic photoreceptor thus formed could be used as a normal cylindrical electrophotographic photoreceptor rather than a belt. Durability was 20,000 in number of prints and was judged to be a life due to wear of the charge transport layer. Then, after immersing again in liquid nitrogen and cooling, removing the belt-shaped electrophotographic photosensitive member, the new belt-shaped electrophotographic photosensitive member of Example 2 was fitted in the same manner to continue the aluminum cylindrical substrate. Could be used.
[0126]
(Example 3)
A belt-shaped electrophotographic apparatus according to the same procedure and conditions as in Example 1 except that the amount of carbon black mixed in the coating solution containing the PI precursor was 22% by mass with respect to the solid component in the coating solution. A photoconductor was prepared. In this case, the volume resistance of the seamless base belt is about 10%. ^Three It was Ωcm. Then, an electrophotographic characteristic evaluation test was performed under the same conditions as in Example 1. Generation of black spots was not confirmed in prints of 5,000 sheets or less, but when images were created by repeating printing exceeding 10,000 sheets, it was confirmed that 1 to 2 black spots were generated. When the photosensitive layer of the portion was examined, there was a charging failure portion due to abnormal discharge. That is, in the case of the contact charging method, an image of a level that can withstand actual use can be obtained with a print of 5,000 sheets or less, but the volume resistivity of the seamless substrate belt is 10 ^Five It was confirmed that if it is less than Ωcm, the effect of preventing abnormal discharge is reduced.
[0127]
A belt-like electrophotographic photosensitive member similar to this belt-like electrophotographic photosensitive member was produced, and a test similar to the above-described electrophotographic characteristic evaluation test was performed except that the charging method was changed to the corona charging method. In the case of this charging method, generation of black spots due to abnormal discharge (leakage) was not confirmed.
[0128]
(Example 4)
A belt-shaped electrophotographic apparatus according to the same procedure and conditions as in Example 1 except that the amount of carbon black mixed in the coating solution containing the PI precursor was 15% by mass with respect to the solid component in the coating solution. A photoconductor was prepared. In this case, the volume resistance of the seamless base belt is about 10%. ⁹ It was Ωcm. Then, an electrophotographic characteristic evaluation test was performed under the same conditions as in Example 1. Although 10,000 images were created, the occurrence of black spots due to abnormal discharge (leakage) was not confirmed.
[0129]
【The invention's effect】
As described above, according to the method for producing a belt-shaped electrophotographic photoreceptor of the present invention, a photosensitive layer having a uniform thickness can be easily formed, and high production efficiency can be obtained. Further, the belt-like electrophotographic photoreceptor of the present invention thus obtained is provided with a photosensitive layer having a uniform thickness, so that excellent output image quality can be obtained. Further, the image forming apparatus of the present invention provided with this belt-shaped electrophotographic photosensitive member can also obtain excellent output image quality.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a basic configuration of a dip coating apparatus for performing a first step according to the present invention.
2 is a front view when the dip coating apparatus shown in FIG. 1 is viewed from a direction parallel to the central axis of the core body 1. FIG.
FIG. 3 is a schematic cross-sectional view showing an example of a basic configuration of a dip coating apparatus for performing a third step according to the present invention.
FIG. 4 is a schematic cross-sectional view showing a basic configuration of a preferred embodiment of a belt-shaped electrophotographic photosensitive member of the present invention.
5 is a schematic cross-sectional view showing another example of the basic configuration of the dip coating apparatus for performing the first step according to the present invention shown in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Core body, 2 ... Coating liquid for base formation, 3 ... Coating tank, 4 ... Liquid film | membrane which consists of coating liquid for base formation, 5 ... Ring body, 6 ... Hole, 7 ... Ring coating tank, 8 DESCRIPTION OF SYMBOLS ... Sealing material, 9 ... Lid member, 10 ... Seamless base belt, 11 ... Coating material, 12 ... Coating liquid for forming photosensitive layer, 13 ... Coating tank, 14 ... Liquid film comprising coating liquid for forming photosensitive layer 20 ... belt-shaped electrophotographic photosensitive member, 71 ... opening, 100, 100A ... dip coating apparatus for forming a seamless substrate belt, 200 ... dip coating for forming a photosensitive layer Device, d16... A gap between the annular body 5 and the core body 1.

Claims (6)

A method for producing a belt-like electrophotographic photoreceptor comprising at least a belt-like conductive substrate without a seam, and a photoreceptor layer containing at least a pigment and disposed on the outer surface of the substrate,
Applying a coating liquid for forming the substrate containing at least a conductive material and a polyimide precursor to the surface of a predetermined portion where the substrate of the columnar or cylindrical core is to be formed, and applying the coating liquid to the surface of the core A first step of forming a liquid film comprising a coating liquid for forming a substrate;
A second step of heating the liquid film to form the substrate made of a film containing at least the conductive material and the polyimide;
A third step of forming the photosensitive layer by applying the coating solution for forming the photosensitive layer containing at least the pigment to the surface of the substrate while maintaining the state where the core and the substrate are integrated; ,
Including a fourth step of removing the core body from the base body,
A method for producing a belt-like electrophotographic photosensitive member. In the first step, an annular body provided with a circular hole having an inner diameter larger than the outer diameter of the cross section of the core body is floated on the coating liquid for forming the substrate, and the core is passed through the hole of the annular body. Immersing the body in the coating liquid for forming the substrate, and then pulling up the core from the coating liquid;
The method for producing a belt-shaped electrophotographic photosensitive member according to claim 1. In the third step, for preventing contact with the coating solution in a region of the surface of the core body that can be contacted with the coating solution when immersed in the coating solution for forming the photosensitive layer. A coating treatment with a coating material is performed in advance, and then the core is immersed in the coating solution.
The method for producing a belt-like electrophotographic photosensitive member according to claim 1 or 2. A belt-shaped electrophotographic photosensitive member having at least a belt-shaped conductive substrate and a photosensitive layer containing a pigment,
A belt-shaped electrophotographic photosensitive member produced by the production method according to claim 1. 5. The belt-shaped electrophotographic photosensitive member according to claim 4, wherein the belt-shaped electrophotographic photosensitive member is used together with a contact charging type charging means, and the volume resistivity of the belt-shaped conductive substrate is 10 ⁵ to 10 ¹⁰ Ωcm. The electrophotographic photosensitive member according to claim 4 or 5,
Charging means for charging the electrophotographic photoreceptor;
Exposure means for exposing the electrophotographic photosensitive member charged by the charging means to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image with toner to form a toner image;
Transfer means for transferring the toner image to a transfer medium;
An image forming apparatus comprising:

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