JP4390409B2

JP4390409B2 - Electrophotographic photosensitive member coating apparatus, coating method, and electrophotographic photosensitive member

Info

Publication number: JP4390409B2
Application number: JP2001243713A
Authority: JP
Inventors: 憲一安田; 信昭小林; 忠昭住谷
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2001-08-10
Filing date: 2001-08-10
Publication date: 2009-12-24
Anticipated expiration: 2021-08-10
Also published as: JP2003057858A

Description

【０００１】
【発明の属する技術分野】
本発明は、電子写真感光体の塗布装置、塗布方法、該塗布方法で製造された電子写真感光体に関し、特に電子写真感光体の製造において円筒状基体の外周面に有機感光層を形成する塗布装置、塗布方法及び該塗布方法により製造された電子写真感光体に関するものである。
【０００２】
【従来の技術】
従来、電子写真感光体の感光層を構成する光導電材料としては、セレン、硫化カドミウム、酸化亜鉛等の無機化合物およびポリビニルカルバゾールに代表される有機化合物が提案されており、また、感光層を電荷発生層と電荷輸送層とに分離した積層型電子写真感光体においては、電荷発生材料および電荷輸送材料として、種々の有機化合物が提案され、有機感光体として実用化されている。従来、このような有機感光体の塗布方法としては、浸漬塗布法、スプレー塗布法、スピン塗布法、ビード塗布法、ワイヤーバー塗布法、ブレード塗布法、ローラー塗布法、押出し塗布法、カーテン塗布法等の各種塗布方法が知られているが、特に円筒状基体の外周面に均一な感光層を形成する方法としては、浸漬塗布法が広く用いられている。
【０００３】
近年、電子写真感光体が使用される複写機、プリンター、ファクシミリ等の装置に対しては、小型化、軽量化の要求が強く、これに伴って電子写真感光体も年々小径化がはかられている。電子写真感光体、特に小径の円筒状基体を使用した電子写真感光体を浸漬塗布法によって製造する方法としては、生産性向上の観点から、特開平５−８８３８５号公報、特開平６−２６２１１３号公報に記載されているように、複数の円筒状基体を同時に塗布液に浸漬し、引き上げる多数本同時浸漬塗布方法が一般的に採用されている。特に、円筒状基体同士の間隔が狭くなれば、さらに生産性が上がり有利となるが、その際に、円筒状基体引上げ時に形成される塗布膜から発生する溶媒蒸気や、塗布槽液面から発生する溶媒蒸気の影響により、円筒状基体上に形成される塗布膜の指触乾燥速度がそれぞれの円筒状基体間、および円筒状基体一本内で不均一となり、膜厚むらを発生してしまう。その回避策としては、特開昭５９−１２７０４９号公報等に記載されているように、円筒状基体が塗布槽液面より引き上げられていない時に、液受け槽近傍に外部よりエアーを送り込み、液受け槽近傍より溶媒蒸気濃度を事前に低減し、指触乾燥速度を促進させるもの、特開平３−１５１号公報等に記載されているように、液受け槽近傍に溶媒蒸気排出口を設け、ＯＮ−ＯＦＦ機構を付与した強制排気装置に連結し、塗布槽液面から引上げ時に円筒状基体周辺の溶媒蒸気濃度を制御するもの等により、膜厚むらを抑制することが行われている。
【０００４】
しかしながら、上記のような技術ではエアー供給口近傍や強制排気装置に連結する溶媒蒸気排出口近辺の円筒状基体の周辺では、溶媒蒸気濃度は低いが、離れた箇所のそれは高くなり、溶媒蒸気濃度の均一化をはかることは困難であった。
【０００５】
即ち、浸漬塗布時において、円筒状基体の周辺の溶媒蒸気濃度が不均一になるという課題に対する従来技術での回避策では、未だ十分ではない。即ち上記のような従来技術では、円筒状基体塗布面の溶媒蒸気濃度が場所により異なり、塗布面の乾燥ムラを引き起こし、その結果塗布膜厚のむらが発生しやすい。
【０００６】
上記溶媒蒸気濃度の不均一化に対する回避策として、例えば、特開平８−２２０７８６号に示された図（図１）のように、リサイクル管８の途中で、且つ塗布槽６の液面より低い位置に溶媒蒸気排出口１２を設けた塗布装置を用い、比重が空気より重く、飽和蒸気濃度が比較的低い溶媒を用いて、塗布層液面上の溶媒蒸気濃度を均一化する方法が提案されている。しかしながらこの方法では、飽和蒸気濃度が低い溶媒を用いることにより、乾燥速度が遅く成りやすく、指触乾燥（指で触ってもべとつかない状態になること）に達するまでに、塗布膜が流れやすくなり、塗布先端の塗布膜が薄くなる先頭薄膜が長くなったり、膜厚むらを発生しやすい。特に、塗布膜厚が厚い電荷輸送層等では先頭薄膜が発生しやすい傾向にある。
【０００７】
【発明が解決しようとする課題】
そこで、本発明は、従来の技術における上記のような問題を解決することを目的としてなされたものである。すなわち、本発明の目的は、円筒状基体引上げ時に形成される塗布膜から発生する溶媒蒸気、および塗布槽液面から蒸発する溶媒蒸気を円筒状基体周辺で、できるだけ均一に排出し、飽和蒸気濃度が高い塩化メチレン等の溶媒を用いても、均一に溶媒を排出でき、且つ乾燥膜厚が１０μｍ以上の電荷輸送層等を塗布しても膜厚むらが小さく、先頭薄膜が短い電子写真感光体の塗布装置を提供することにある。本発明の他の目的は、前記塗布装置を用いて、円筒状基体上に膜厚むらのない感光層等を形成することができる電子写真感光体の塗布方法を提供すること、及び該塗布方法を用いて製造された電子写真感光体を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の上記課題は以下のような構成により達成される。
【０００９】
１．円筒状基体を塗布液中に浸漬し、引き上げて該円筒状基体上に塗布膜を形成する電子写真感光体の塗布装置において、該塗布装置は塗布液を収容する塗布槽、該塗布槽上に設けられた溶媒蒸気溜室、該溶媒蒸気溜室上方に設けられた乾燥フードを有し、該溶媒蒸気溜室は塗布槽上方全面を覆い、溶媒蒸気溜室とその上の乾燥フードとの間で且つ円筒状基体を取り巻くように、溶媒蒸気溜室より上に位置し、間隙幅が０．２〜８ｍｍの溶媒蒸気を系外に排出する排出口を設けてなることを特徴とする電子写真感光体の塗布装置。
【００１１】
２．前記排出口が乾燥フード周囲長の５０〜１００％の開口比で形成されていることを特徴とする前記１に記載の電子写真感光体の塗布装置。
【００１２】
３．前記溶媒蒸気溜室にはリサイクル管が接続しており、オーバーフローする塗布液をリサイクル管で回収して循環させることを特徴とする前記１又は２に記載の電子写真感光体の塗布装置。
【００１３】
４．前記１〜３のいずれか１項に記載の電子写真感光体の塗布装置を用いた電子写真感光体の塗布方法において、前記排出口より溶媒蒸気を排出させながら、円筒状基体上に塗布膜を形成することを特徴とする電子写真感光体の塗布方法。
【００１４】
５．円筒状基体に塗布膜厚が３０〜３００μｍに成るように浸漬塗布を行うことを特徴とする前記４に記載の電子写真感光体の塗布方法。
【００１５】
６．前記塗布液の溶媒として飽和蒸気圧（２４℃）が６．５〜８０ｋＰａの溶媒を用いることを特徴とする前記４又は５に記載の電子写真感光体の塗布方法。
【００１６】
７．複数の円筒状基体を同時に塗布液中に浸漬し、引上げて塗布層を形成することを特徴とする前記４〜６のいずれか１項に記載の電子写真感光体の塗布方法。
【００１７】
８．塗布液が電荷輸送層形成用塗布液であることを特徴とする前記４〜７のいずれか１項に記載の電子写真感光体の塗布方法。
【００１９】
以下、本発明を詳細に説明する。
即ち、円筒状基体を塗布液中に浸漬し、引き上げて該円筒状基体上に塗布膜を形成する電子写真感光体の塗布装置において、該塗布装置は塗布液を収容する塗布槽、該塗布槽上に設けられた溶媒蒸気溜室、該溶媒蒸気溜室上方に設けられた乾燥フードを有し、該溶媒蒸気溜室は塗布槽上方全面を覆い、溶媒蒸気溜室とその上の乾燥フードとの間で且つ円筒状基体を取り巻くように、溶媒蒸気溜室より上に位置し、間隙幅が０．２〜８ｍｍの溶媒蒸気を系外に排出する排出口を設けてなることを特徴とする。
【００２０】
又、本発明の電子写真感光体の塗布方法は、上記の電子写真感光体の塗布装置を用いた電子写真感光体の塗布方法において、前記排出口より溶媒蒸気を排出させながら、円筒状基体上に塗布膜を形成することを特徴とする。
【００２１】
又、本発明の電子写真感光体は上記電子写真感光体の塗布方法を用いて製造されることを特徴とする。
【００２２】
本発明における塗布方法は、塗布槽の上に設置される乾燥フードを溶媒蒸気溜室と乾燥フードに分離し、且つ溶媒蒸気溜室と乾燥フードの間に排気口を設けた塗布装置を用い、該排気口から溶媒蒸気を排出させることにより、溶媒蒸気溜室全体の溶媒蒸気濃度を均一にし、塗布直後の溶媒蒸気濃度を基体間、或いは基体の円周方向による差をなくすことにより、膜厚むらを小さくする事が出来る。特に塩化メチレン等の飽和蒸気濃度が大きい溶媒を用いた場合でも、膜厚むらの発生が小さくなり、且つ先頭薄膜の長さを短くすることが出来る。即ち、溶媒蒸気溜室の真上に排出口を設けることにより、溶媒蒸気の排出が容易となり、塗布直後の大量の溶媒蒸気を排出できる。又、円筒状基体の周辺から均一に溶媒蒸気を排出出来るため、１本の塗布装置においても、多数本の塗布装置においても溶媒蒸気溜室中の溶媒濃度を全体に均一状態に保ちながら溶媒を系外に排出できる。その結果、塗布膜厚（塗布直後の溶媒を含んだ塗布液膜厚）が３０〜３００μｍの広い範囲で膜厚むらを小さくでき、且つ先頭薄膜を短くすることが出来る。
【００２３】
又、飽和蒸気圧が６．５〜８０ｋＰａの広い範囲から溶媒を選択しても、膜厚むら及び先頭薄膜を短くする改良効果を持続することが出来る。
【００２４】
ここにおいて、先頭薄膜とは塗布直後の塗布膜が重力の影響を受けて流下し、塗布先端部において、膜厚が薄くなる現象を意味し、塗布膜厚が厚く、乾燥速度が遅い電荷輸送層等で発生しやすい。図４に電荷輸送層を塗布した感光体の膜厚プロフィールを示した。ａが先頭薄膜部を示す。
【００２５】
また、本発明は、有機感光体の下引き層、電荷発生層、電荷輸送層等の形成に好適に適用することができる。特に塗布膜厚が１００μｍを超え、膜厚むらや先頭薄膜の発生が大きい電荷輸送層に本発明の塗布方法を適用すると好結果が得られる。また、本発明は、複数の円筒状基体の外周面に同時に塗布膜を形成させる多数本同時塗布に特に有効である。その際、塗布槽に配列する複数本の円筒状基体が均一な溶媒蒸気排出効果を上げるために、各円筒状基体の配置構成がそれぞれ等しい条件となるような塗布槽が好ましい。即ち、図５に示すような４本同時塗布の円筒状の塗布槽が好ましく、５本以上の塗布装置では互いに隣接する円筒状基体の距離が等しくなるように配置するのが好ましい。
【００２６】
図２は、本発明の１本取り浸漬塗布装置の一例の概略構成を示すものであり、円筒状基体９は塗布槽６で浸漬塗布をされた後、塗布槽から引き上げの途中にある。本発明において円筒状基体は塗布槽から引き上げられると、溶媒蒸気溜室１１に入り、ここで塗布膜が大量の溶媒蒸気を放出し、次の乾燥フード１４に送られ指触乾燥の状態（指で触ってもべとつかない状態）に乾燥される。本発明では前記溶媒蒸気溜室１１と乾燥フード１４の間に排出口１２を設けることにより、塗布液に高い飽和蒸気圧の溶媒を用いた場合でも、又大量の溶媒蒸気を放出する１００μｍ以上の塗布膜を形成したときにも溶媒蒸気溜室１１内の溶媒蒸気濃度を全体に均一に維持しながら、大量の溶媒蒸気を放出することができ、塗布膜の指触乾燥むらの発生や、先頭薄膜の増大を防止する。
【００２７】
ここで、溶媒蒸気溜室とは塗布層を覆い、塗布液や塗布膜から発生する溶媒蒸気を一旦、よどませ、溶媒蒸気濃度が均一な雰囲気を保つための部屋である。前記溶媒蒸気溜室の高さは１ｃｍ〜１００ｃｍが好ましい。１ｃｍ未満では溶媒蒸気溜室を設けた効果が小さく、膜厚むらの発生等の防止効果が小さい。一方１００ｃｍより大きくても、装置が大型化するに見合った効果が得られない。
【００２８】
本発明の排出口は塗布された基体が引き上げられたとき、円筒状基体を取り巻くように溶媒蒸気溜室と乾燥フードの間に形成されている。即ち、前記排出口１２は溶媒蒸気溜室と乾燥フードの間に０．１〜１０ｍｍの間隙幅で設置するのが好ましい。０．１ｍｍ未満では溶媒蒸気の排出量が十分でなく、１０ｍｍ以上だと溶媒蒸気の排出は十分であるが、溶媒蒸気溜室が外部空気の流れの影響を受けやすく、溶媒蒸気溜室の溶媒蒸気濃度の均一性が乱されやすい。
【００２９】
前記溶媒蒸気溜室の上部蓋部分には円筒状基体を通過させるに必要な開口部（穴）が設けられている。この開口部は円筒状基体と同様に円形が好ましい。
【００３０】
又、溶媒蒸気溜室の上部に設置される乾燥フード（円筒状基体を取り囲む構造を有する）の長さは５ｃｍ〜３００ｃｍが好ましい。５ｃｍ未満では乾燥フードの効果が小さく、膜厚むらの発生等の防止効果が小さい。一方３００ｃｍより大きくても、装置が大型化するに見合った効果が得られない。
【００３１】
又、前記溶媒蒸気溜室にはリサイクル管を設置し、塗布槽の液面を一定に保持することが好ましい。即ち、図２に示すような構成とすることが好ましい。即ち、塗布液１は、塗布液タンク２から供給配管３を通してポンプ４によって圧送され、フィルター５を介して塗布槽６内に供給される。塗布槽６に供給された塗布液はオーバーフローし、溶媒蒸気溜室１１の下端に連続して設けられた塗布液受け槽７で補集されリサイクル管８に流出し、塗布液タンク２に回収される。この浸漬塗布装置を用いて浸漬塗布を行う場合、円筒状基体９が塗布槽６に浸漬され、その後、引き上げられた時、塗布槽液面１０を一定に保持する目的で、常にオーバーフローするように塗布液循環手段によって塗布液を循環する。さらに、溶媒蒸気溜室の上に溶媒蒸気を排出する排出口１２が設けられているが、排出口１２は、塗布槽液面１０より高い位置に設けられている。また、溶媒蒸気溜室１１の上部には、外部空気の流れの影響を防止するため乾燥フード１４を設けている。ここで、排出口１２を設けない場合や、特開平８−２２０７８６のように排出口１２を塗布槽液面１０より低いリサイクル管８の途中に設置した場合は、飽和蒸気圧が高い塩化メチレン溶媒に用いる場合や、大量の溶媒蒸気を放出する１００μｍ以上の塗布膜を形成したときには溶媒蒸気溜室１１内の溶媒蒸気濃度を十分に排出できず、溶媒蒸気が円筒状基体周辺に滞留し、円筒状基体９に形成される塗布膜の指触乾燥ムラを発生させ、先頭薄膜を増大させる。しかしながら、本発明においては、溶媒蒸気を排出する排出口１２を溶媒蒸気溜室の上で塗布槽液面１０より高い位置に設けているから、例え飽和蒸気濃度の高い溶媒を用いても円筒状基体周辺の溶媒蒸気を均一に排出することが可能となり、その効果により膜厚むらの発生や、先頭薄膜の増大を防止することができる。
【００３２】
図３は本発明の多数本同時浸漬塗布装置の一例の概略構成を示すものであり、円筒状基体を塗布槽から引上げ途中の状態を示すものである。塗布液１は、塗布液タンク２から供給配管３を通してポンプ４によって圧送され、フィルター５を介して塗布槽６内に供給される。塗布槽６は槽内塗布液流速均一性を得るために下部にメッシュ１５を挿入してある。塗布槽６内に供給された塗布液はオーバーフローし、塗布槽６の上部に設置された溶媒蒸気溜室１１の下端で連続した塗布液受け槽７で補集されリサイクル管８に流出し、塗布液タンク２に回収される。この浸漬塗布装置を用いて浸漬塗布を行う場合、円筒状基体９が塗布槽６に浸漬され、その後、引き上げられた時、塗布槽液面１０を一定に保持する目的で、常にオーバーフローするように循環手段によって塗布液を循環する。さらに、塗布槽の上方に溶媒蒸気溜室が設置され、更に溶媒蒸気溜室の上に乾燥フードが設けられている。そして、溶媒蒸気溜室と乾燥フードの間に溶媒蒸気を排出する排出口１２が設けられている。排出口１２は、塗布槽液面１０より高い位置に設けられている。
【００３３】
乾燥フードは多数本塗布の場合には、溶媒蒸気溜室の上に、溶媒蒸気溜室と同型の外壁構造で設置する事も可能であるが、個々の円筒状基体の周辺の溶媒蒸気濃度を一定に維持するためには、乾燥フードを個々の円筒状基体に独立に設置することが好ましい。図３には多数の円筒状基体にそれぞれ独立に乾燥フードを設置した例を図示する。
【００３４】
又、乾燥フードには乾燥中の溶媒蒸気を排出するための多数の通気口を設けることが好ましい。該通気口の全体の開口面積比は乾燥フード全体の面積に対して５〜７０％が好ましい。５％未満だと溶媒蒸気の排出が十分でなく、７０％を超えると乾燥速度の調製が難しい。
【００３５】
本発明において、円筒状基体としては、電子写真感光体において使用される公知の導電性のものが使用される。また、円筒状基体に塗布される感光体形成用塗布液としては、公知の材料ならどのようなものでも使用可能である。例えば、下引き層塗布液、電荷発生層塗布液、電荷輸送層塗布液等が使用され、それにより感光体構成層である下引き層、電荷発生層、電荷輸送層が形成される。しかしながら、他の感光層構成層、例えば、中間層、表面層等を形成するための塗布液を使用することも可能である。
【００３６】
本発明に用いられる溶媒としては、一般的に、有機感光層形成用塗布液に使用される有機溶媒であればその殆どが含まれる。具体的には、例えば、塩化メチレンのようなハロゲン化炭化水素、エチルアルコールのようなアルコール、シクロヘキサノンのようなケトン等があげられる。
【００３７】
【実施例】
以下、本発明を実施例によって具体的に説明する。
【００３８】
実施例１
以下の様にして、円筒状基体上に中間層を形成した。
【００３９】
ポリアミド樹脂ＣＭ８０００（東レ社製）１質量部、メタノール１０質量部を同一容器中に加え溶解分散して、中間層塗布液１を作製した。該中間層塗布液を図２の浸漬塗布装置を用いて円筒状アルミニウム基体（１．０ｍｍｔ×３０ｍｍφ×３４０ｍｍ）上に塗布した。その時の塗布液温度は２４℃とした。アルミニウム基体を塗布液から引き上げる速度は４８０ｍｍ／ｍｉｎとした。排出口１２の位置としては、図２に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。また、塗布液循環流量は１Ｌ／ｍｉｎ、リサイクル管８の径は、内径１００ｍｍφとした。塗布した基体は１５ｃｍの乾燥フードを経由し風乾した後、乾燥機に入れ、７０℃において、１０分間加熱乾燥し、膜厚０．１μｍの中間層を形成した。
【００４０】
次にＹ型チタニルフタロシアニン６０ｇ、シリコーン変性ブチラール樹脂（信越化学社製）７００ｇ、２−ブタノン２０００ｍｌを混合し、サンドミルを用いて１０時間分散し、電荷発生層塗布液を調製した。この塗布液を図２の浸漬塗布装置を用いて、上記実施例１により得られた中間層が形成されたアルミニウム基体の上に塗布した。アルミニウム基体を塗布液から引き上げる速度は４８０ｍｍ／ｍｉｎとした。その時の塗布液温度は２４℃とした。排出口１２の位置としては、図２に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。また、塗布液循環流量は１Ｌ／ｍｉｎ、リサイクル管８の径は、内径１００ｍｍφの条件で塗布を行った。
【００４１】
次いで上記で形成された電荷発生層の上に、電荷輸送層を形成した。電荷輸送物質〔Ｎ−（４−メチルフェニル）−Ｎ−｛４−（β−フェニルスチリル）フェニル｝−ｐ−トルイジン〕２２５ｇ、ポリカーボネート（粘度平均分子量２０，０００）３００ｇ、酸化防止剤（例示化合物１−３）６ｇ、ジクロロメタン２０００ｍｌを混合し、溶解して電荷輸送層塗布液を調製した。この塗布液を前記電荷発生層の上に浸漬塗布法で塗布し、乾燥膜厚２０μｍの電荷輸送層を形成した。アルミニウム基体を塗布液から引き上げる速度は２４０ｍｍ／ｍｉｎとした。その時の塗布液温度は２４℃とした。排出口１２の位置としては、図２に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。また、塗布液循環流量は１Ｌ／ｍｉｎ、リサイクル管の径は、内径１００ｍｍφとした。塗布したアルミニウム基体は、１５ｃｍの乾燥フードを経由して風乾した後、乾燥機に入れ、９０℃において、６０分間加熱乾燥し、電荷輸送層を形成し、電子写真感光体ドラムを作製した。その条件で、４回繰り返し塗布を行った。それぞれの膜厚むら値を表３に示す。膜厚むら値は、塗布膜上端から２０ｍｍ、５０ｍｍ、１６０ｍｍ、３００ｍｍのそれぞれの箇所の円周方向（９０°間隔）、合計１６点の膜厚値の最大値と最少値の差である。ここで、２４℃におけるジクロロメタンの飽和蒸気圧は、約４６．６ｋＰａ、空気に対する比重は約１．３２６であった。
【００４２】
比較例１
比較のために、排出口を図１記載のように塗布液面より下部に位置するリサイクル管８の途中に取り付けた以外は、実施例１と同一の条件で前記電荷発生層の上に電荷輸送層の塗布を行った。その結果を表１に示す。
【００４３】
【表１】

【００４４】
実施例２
実施例１で用いた中間層塗布液を用いて、図３及び図５に図示の４本同時塗布装置を用いて塗布を行った（図５は４本同時塗布の基体の配列方法の図）。円筒状アルミニウム基体を塗布液から引き上げる速度は４００ｍｍ／ｍｉｎとし、この時の塗布温度は２４℃とした。排出口１２の位置としては、図３に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。また、塗布液循環流量は５Ｌ／ｍｉｎ、リサイクル管の径は、内径１５０ｍｍφとした。塗布したアルミニウム基体は１５ｃｍの乾燥フードを経由して風乾した後、乾燥機に入れ、７０℃において、１０分間加熱乾燥し、膜厚０．１μｍの中間層を形成した。
【００４５】
次に電荷発生層塗布液を用いて、図３・図５に図示の４本同時塗布装置を用いて、上記中間層が形成されたアルミニウム基体の上に塗布した。アルミニウム基体を塗布液から引き上げる速度は４８０ｍｍ／ｍｉｎとした。この時の塗布温度は２４℃とした。排出口１２の位置としては、図３に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。、また、塗布液循環流量は５Ｌ／ｍｉｎ、リサイクル管の径は、内径１５０ｍｍφとした。塗布したアルミニウム基体は１５ｃｍの乾燥フードを経由して風乾した後、指触乾燥（指で触ってもべとつかない乾燥状態）の電荷発生層（乾燥膜厚は０．５μｍ）を形成した。
【００４６】
上記の電荷発生層の上に、実施例１と同じ電荷輸送層塗布液を用いて前記電荷発生層の上に浸漬塗布法で塗布し、乾燥膜厚２０μｍの電荷輸送層を形成した。アルミニウム基体を塗布液から引き上げる速度は２４０ｍｍ／ｍｉｎとし、同時塗布本数は４本とした。この時の塗布温度は２４℃とした。排出口１２の位置としては、図３に示す溶媒蒸気溜室と乾燥フードの間に間隙幅１ｍｍで設置されている。該排出口は塗布槽液面から１０ｃｍの高さに５０ｍｍの円で形成されている。また、塗布液循環流量は５Ｌ／ｍｉｎ、リサイクル管の径は、内径１５０ｍｍφとした。塗布したアルミニウム基体は１５ｃｍの乾燥フードを経由して風乾した後、乾燥機に入れ、９０℃において、６０分間加熱乾燥し、電荷輸送層を形成し、電子写真感光体ドラムを作製した。その時の４本それぞれの膜厚むら値を表６に示す。ここで、膜厚むら値は、塗布膜上端から２０ｍｍ、５０ｍｍ、１６０ｍｍ、３００ｍｍのそれぞれの箇所の円周方向４点（９０°間隔）、合計１６点の膜厚値の最大値と最小値の差である。その結果を表２に示す。
【００４７】
比較例２
比較のために、排出口を塗布液面より下部に位置するリサイクル管８の途中に取り付けた以外は、実施例２と同一条件で前記電荷発生層上に電荷輸送層の塗布を行った。その結果を表２に示す。
【００４８】
実施例３
排出口１２の間隔幅を８ｍｍとした以外は、実施例２と同一の条件で前記電荷発生層上に電荷輸送層の塗布を行ったその結果を表２に示す。
【００４９】
実施例４
排出口１２の間隔幅を０．２ｍｍとした以外は、実施例２と同一条件で前記電荷発生層上に電荷輸送層の塗布を行った。その結果を表２に示す。
【００５０】
又、実施例２〜４、及び比較例２の各感光体について先頭薄膜の評価を行った。結果を表３に示す。
＊先頭薄膜の評価
円筒状感光体のドラム軸に沿って任意に一本の直線を選定する。該直線の塗布先頭部から１０ｍｍ等間隔に感光層の膜厚を測定し、図４に示したような感光体膜厚プロフィールを作製する。先頭薄膜の長さＬは、感光体のドラム先端から先頭部膜厚立ち上がりの接線と飽和膜厚の延長戦の交点迄の長さａと定義する。各感光体について、先頭薄膜長さを測定し、その結果を表３に示した。膜厚測定器は光検出方式の膜厚測定器ＭＣＰＤ−１０００（瞬間マルチ測光検出器：大塚電子（株））を用いて行った。
【００５１】
【表２】

【００５２】
【表３】

【００５３】
表１、表２、表３から判るように塗布槽上方に溶媒蒸気留室を設け、且つ、溶媒蒸気留室と乾燥フードの間に溶媒蒸気の排出口を設けた本発明の電子写真感光体の塗布装置は、比較例で示した従来のリサイクル管の途中に溶媒蒸気の排出口を設けた塗布装置に比べ、電荷輸送層を塗布した後の膜厚むら及び先頭薄膜の長さのいずれにおいても著しい改善効果が見られる。
【００５４】
【発明の効果】
上記の実施例からも明らかなように、本発明の電子写真感光体の塗布装置及び塗布方法を用いれば、各円筒状基体に形成された感光層は膜厚むらが小さく、先頭薄膜の長さも短いものを作製することができ、したがって性能が良好な円筒状の電子写真感光体を提供することが可能である。
【図面の簡単な説明】
【図１】リサイクル管の途中で、且つ塗布槽の液面より低い位置に溶媒蒸気排出口を設けた塗布装置の図である。
【図２】本発明の１本取り浸漬塗布装置の一例の概略構成を示す図である。
【図３】本発明の多数本同時浸漬塗布装置の一例の概略構成を示す図である。
【図４】電荷輸送層を塗布した感光体の膜厚プロフィールを示した図である。
【図５】４本同時塗布の基体の配列方法の図である。
【符号の説明】
１塗布液
２塗布液タンク
３供給配管
４ポンプ
５フィルター
６塗布槽
７塗布液受け槽
８リサイクル管
９円筒状基体
１０塗布槽液面（オーバーフロー面）
１１溶媒蒸気溜室
１２排出口
１４乾燥フード
１５メッシュ[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member coating apparatus, a coating method, and an electrophotographic photosensitive member produced by the coating method, and more particularly, coating for forming an organic photosensitive layer on the outer peripheral surface of a cylindrical substrate in the production of an electrophotographic photosensitive member. The present invention relates to an apparatus, a coating method, and an electrophotographic photosensitive member produced by the coating method.
[0002]
[Prior art]
Conventionally, inorganic compounds such as selenium, cadmium sulfide, and zinc oxide and organic compounds typified by polyvinyl carbazole have been proposed as the photoconductive material constituting the photosensitive layer of the electrophotographic photosensitive member. In a laminated electrophotographic photoreceptor separated into a generation layer and a charge transport layer, various organic compounds have been proposed as a charge generation material and a charge transport material and put into practical use as an organic photoreceptor. Conventionally, such organic photoconductor coating methods include dip coating, spray coating, spin coating, bead coating, wire bar coating, blade coating, roller coating, extrusion coating, and curtain coating. In particular, as a method for forming a uniform photosensitive layer on the outer peripheral surface of a cylindrical substrate, a dip coating method is widely used.
[0003]
In recent years, there has been a strong demand for downsizing and weight reduction in apparatuses such as copying machines, printers, and facsimile machines that use electrophotographic photosensitive members, and accordingly, the diameter of electrophotographic photosensitive members has been decreasing year by year. ing. As a method for producing an electrophotographic photosensitive member, particularly an electrophotographic photosensitive member using a small-diameter cylindrical substrate, by a dip coating method, from the viewpoint of improving productivity, JP-A-5-88385 and JP-A-6-262113. As described in the gazette, a multiple simultaneous dip coating method in which a plurality of cylindrical substrates are simultaneously dipped in a coating solution and pulled up is generally employed. In particular, if the distance between the cylindrical substrates is reduced, the productivity is further increased, which is advantageous. In this case, it is generated from the solvent vapor generated from the coating film formed when the cylindrical substrate is pulled up or from the coating tank liquid level. Due to the influence of the solvent vapor, the touch-drying speed of the coating film formed on the cylindrical substrate becomes uneven between the cylindrical substrates and within one cylindrical substrate, resulting in uneven film thickness. . As a workaround, as described in JP-A-59-127049 and the like, when the cylindrical substrate is not pulled up from the liquid level of the coating tank, air is sent from the outside to the vicinity of the liquid receiving tank, Reducing the solvent vapor concentration in the vicinity of the receiving tank and promoting the touch drying speed, as described in JP-A-3-151, etc., provided a solvent vapor outlet near the liquid receiving tank, It is connected to a forced exhaust apparatus provided with an ON-OFF mechanism, and the film thickness unevenness is suppressed by means of controlling the solvent vapor concentration around the cylindrical substrate when pulled up from the coating tank liquid level.
[0004]
However, in the technology as described above, the solvent vapor concentration is low in the vicinity of the cylindrical substrate near the air supply port or in the vicinity of the solvent vapor discharge port connected to the forced exhaust device, but it is high in the distant place, and the solvent vapor concentration is high. It was difficult to achieve uniformization.
[0005]
That is, the conventional workaround for the problem of non-uniform solvent vapor concentration around the cylindrical substrate during dip coating is still not sufficient. That is, in the conventional technology as described above, the solvent vapor concentration on the coated surface of the cylindrical substrate varies from place to place, causing uneven drying on the coated surface, and as a result, uneven coating film thickness tends to occur.
[0006]
As a workaround for the non-uniformity of the solvent vapor concentration, for example, as shown in FIG. 1 (FIG. 1) shown in JP-A-8-220786, it is lower in the middle of the recycle pipe 8 and lower than the liquid level of the coating tank 6. A method of using a coating apparatus having a solvent vapor outlet 12 at a position and using a solvent having a specific gravity heavier than air and a relatively low saturated vapor concentration to make the solvent vapor concentration on the coating layer liquid surface uniform is proposed. ing. However, with this method, the use of a solvent with a low saturated vapor concentration tends to slow the drying rate, and the coating film tends to flow until it reaches dry touch (becomes a non-sticky state when touched with a finger). The coating film at the coating tip becomes thin, and the leading thin film tends to be long, or uneven film thickness tends to occur. In particular, a leading thin film tends to be easily generated in a charge transport layer having a thick coating film.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention has been made for the purpose of solving the above-described problems in the prior art. That is, the object of the present invention is to discharge the solvent vapor generated from the coating film formed when pulling up the cylindrical substrate and the solvent vapor evaporated from the liquid surface of the coating tank as uniformly as possible around the cylindrical substrate to obtain a saturated vapor concentration. Even if a solvent such as methylene chloride having a high value is used, the solvent can be discharged uniformly, and even when a charge transport layer having a dry film thickness of 10 μm or more is applied, the film thickness unevenness is small and the electrophotographic photosensitive member has a short leading thin film. It is in providing a coating apparatus. Another object of the present invention is to provide a coating method for an electrophotographic photoreceptor capable of forming a photosensitive layer or the like having no film thickness unevenness on a cylindrical substrate using the coating apparatus, and the coating method. It is an object to provide an electrophotographic photosensitive member manufactured using
[0008]
[Means for Solving the Problems]
The above-described object of the present invention is achieved by the following configuration.
[0009]
1. In an electrophotographic photosensitive member coating apparatus in which a cylindrical substrate is immersed in a coating solution and pulled up to form a coating film on the cylindrical substrate, the coating device includes a coating tank for storing the coating solution, and the coating tank. A solvent vapor reservoir chamber provided, and a drying hood provided above the solvent vapor reservoir chamber, the solvent vapor reservoir chamber covering the entire upper surface of the coating tank, and between the solvent vapor reservoir chamber and the drying hood above it. And a solvent vapor chamber so as to surround the cylindrical substrate. Dissolve the solvent vapor with a gap width of 0.2-8mm located outside the system. An electrophotographic photosensitive member coating apparatus comprising a discharge port.
[0011]
2 . The discharge port is formed with an opening ratio of 50 to 100% of the circumference length of the dry hood 1 An electrophotographic photosensitive member coating apparatus as described in 1. above.
[0012]
3 . A recycling pipe is connected to the solvent vapor storage chamber, and the overflowing coating liquid is collected and circulated through the recycling pipe. Or 2 An electrophotographic photosensitive member coating apparatus as described in 1. above.
[0013]
4 . 1 to 3 In the electrophotographic photosensitive member coating method using the electrophotographic photosensitive member coating apparatus according to any one of the above, a coating film is formed on the cylindrical substrate while the solvent vapor is discharged from the discharge port. A method for applying an electrophotographic photosensitive member.
[0014]
5 . The dip coating is performed on the cylindrical substrate so that the coating film thickness is 30 to 300 μm. 4 The method for applying an electrophotographic photosensitive member according to 1.
[0015]
6 . A solvent having a saturated vapor pressure (24 ° C.) of 6.5 to 80 kPa is used as a solvent for the coating solution. 4 or 5 The method for applying an electrophotographic photosensitive member according to 1.
[0016]
7 . A plurality of cylindrical substrates are simultaneously immersed in a coating solution and pulled up to form a coating layer. 4-6 The electrophotographic photosensitive member coating method according to any one of the above.
[0017]
8 . The coating liquid is a coating liquid for forming a charge transport layer, 4-7 The electrophotographic photosensitive member coating method according to any one of the above.
[0019]
Hereinafter, the present invention will be described in detail.
That is, in an electrophotographic photosensitive member coating apparatus in which a cylindrical substrate is dipped in a coating solution and pulled up to form a coating film on the cylindrical substrate, the coating device includes a coating tank that stores the coating solution, and the coating tank. A solvent vapor reservoir chamber provided above, and a drying hood provided above the solvent vapor reservoir chamber, the solvent vapor reservoir chamber covering the entire upper surface of the coating tank, and a solvent vapor reservoir chamber and a drying hood thereon Between And the solvent vapor having a gap width of 0.2 to 8 mm is discharged out of the system so as to surround the cylindrical substrate. A discharge port is provided.
[0020]
The electrophotographic photosensitive member coating method of the present invention is an electrophotographic photosensitive member coating method using the above-described electrophotographic photosensitive member coating apparatus, wherein the solvent vapor is discharged from the outlet while the solvent vapor is exhausted. A coating film is formed on the substrate.
[0021]
In addition, the electrophotographic photosensitive member of the present invention is manufactured using the above-described electrophotographic photosensitive member coating method.
[0022]
The coating method in the present invention uses a coating apparatus in which a drying hood installed on a coating tank is separated into a solvent vapor reservoir and a drying hood, and an exhaust port is provided between the solvent vapor reservoir and the drying hood. By exhausting the solvent vapor from the exhaust port, the solvent vapor concentration in the entire solvent vapor reservoir is made uniform, and the solvent vapor concentration immediately after coating is eliminated between the substrates or by the difference in the circumferential direction of the substrate. Unevenness can be reduced. In particular, even when a solvent having a high saturated vapor concentration such as methylene chloride is used, the occurrence of film thickness unevenness is reduced and the length of the leading thin film can be shortened. That is, by providing a discharge port directly above the solvent vapor reservoir, the solvent vapor can be easily discharged, and a large amount of solvent vapor immediately after coating can be discharged. In addition, since the solvent vapor can be uniformly discharged from the periphery of the cylindrical substrate, the solvent can be removed while maintaining the solvent concentration in the solvent vapor reservoir chamber as a whole in a single coating apparatus or multiple coating apparatuses. Can be discharged outside the system. As a result, the coating film thickness (coating liquid film thickness including the solvent immediately after coating) can be reduced in a wide range of 30 to 300 μm, and the leading thin film can be shortened.
[0023]
Even if the solvent is selected from a wide range of saturated vapor pressure of 6.5 to 80 kPa, the improvement effect of shortening the film thickness unevenness and the leading thin film can be maintained.
[0024]
Here, the leading thin film means a phenomenon in which the coating film immediately after coating flows down under the influence of gravity and the film thickness becomes thin at the coating tip, and the charge transport layer has a large coating film thickness and a slow drying rate. Etc. FIG. 4 shows a film thickness profile of a photoreceptor coated with a charge transport layer. a indicates the leading thin film portion.
[0025]
In addition, the present invention can be suitably applied to the formation of an undercoat layer, a charge generation layer, a charge transport layer, and the like of an organic photoreceptor. In particular, good results can be obtained when the coating method of the present invention is applied to a charge transport layer in which the coating film thickness exceeds 100 μm and the generation of film thickness unevenness and leading thin film is large. The present invention is particularly effective for simultaneous application of a large number of coating films in which a coating film is simultaneously formed on the outer peripheral surfaces of a plurality of cylindrical substrates. At that time, in order for the plurality of cylindrical substrates arranged in the coating tank to improve the uniform solvent vapor discharge effect, a coating tank in which the arrangement configuration of each cylindrical substrate is equal is preferable. That is, a four-coating cylindrical coating tank as shown in FIG. 5 is preferable, and in the case of five or more coating apparatuses, it is preferable to arrange the cylindrical substrates adjacent to each other so that the distance between them is equal.
[0026]
FIG. 2 shows a schematic configuration of an example of a single-piece dip coating apparatus of the present invention. The cylindrical substrate 9 is in the middle of being pulled up from the coating tank after being dip coated in the coating tank 6. In the present invention, when the cylindrical substrate is lifted from the coating tank, it enters the solvent vapor reservoir chamber 11 where the coating film releases a large amount of solvent vapor, which is sent to the next drying hood 14 and is in a touch-dried state (finger It is dried to a non-sticky state). In the present invention, by providing a discharge port 12 between the solvent vapor storage chamber 11 and the drying hood 14, even when a solvent having a high saturation vapor pressure is used as the coating solution, a large amount of solvent vapor of 100 μm or more is released. Even when the coating film is formed, a large amount of the solvent vapor can be released while maintaining the uniform concentration of the solvent vapor in the solvent vapor reservoir chamber 11, and the coating film can be touched and dried. Prevents thin film growth.
[0027]
Here, the solvent vapor reservoir chamber is a chamber for covering the coating layer and temporarily stagnating the solvent vapor generated from the coating liquid or coating film to maintain an atmosphere having a uniform solvent vapor concentration. The height of the solvent vapor storage chamber is preferably 1 cm to 100 cm. If it is less than 1 cm, the effect of providing the solvent vapor reservoir is small, and the effect of preventing the occurrence of film thickness unevenness is small. On the other hand, even if it is larger than 100 cm, an effect commensurate with the increase in size of the apparatus cannot be obtained.
[0028]
The discharge port of the present invention is formed between the solvent vapor reservoir and the drying hood so as to surround the cylindrical substrate when the coated substrate is pulled up. That is, the discharge port 12 is preferably installed with a gap width of 0.1 to 10 mm between the solvent vapor storage chamber and the drying hood. If it is less than 0.1 mm, the amount of solvent vapor discharged is not sufficient, and if it is 10 mm or more, solvent vapor is sufficiently discharged. However, the solvent vapor reservoir is easily affected by the flow of external air, and the solvent vapor Vapor density uniformity is likely to be disturbed.
[0029]
An opening (hole) necessary for passing the cylindrical substrate is provided in the upper lid portion of the solvent vapor reservoir. The opening is preferably circular like the cylindrical substrate.
[0030]
Further, the length of the drying hood (having a structure surrounding the cylindrical substrate) installed in the upper part of the solvent vapor storage chamber is preferably 5 cm to 300 cm. If it is less than 5 cm, the effect of the dry hood is small, and the effect of preventing the occurrence of film thickness unevenness is small. On the other hand, even if it is larger than 300 cm, an effect commensurate with the increase in size of the apparatus cannot be obtained.
[0031]
In addition, it is preferable to install a recycling pipe in the solvent vapor storage chamber to keep the liquid level of the coating tank constant. That is, the configuration as shown in FIG. 2 is preferable. That is, the coating liquid 1 is pumped from the coating liquid tank 2 through the supply pipe 3 by the pump 4 and supplied into the coating tank 6 through the filter 5. The coating liquid supplied to the coating tank 6 overflows, is collected in the coating liquid receiving tank 7 provided continuously at the lower end of the solvent vapor storage chamber 11, flows out into the recycling pipe 8, and is collected in the coating liquid tank 2. The When dip coating is performed using this dip coating apparatus, when the cylindrical substrate 9 is immersed in the coating tank 6 and then pulled up, it always overflows for the purpose of keeping the coating tank liquid level 10 constant. The coating liquid is circulated by the coating liquid circulation means. Furthermore, although the discharge port 12 which discharges | emits solvent vapor | steam is provided on the solvent vapor storage chamber, the discharge port 12 is provided in the position higher than the coating tank liquid level 10. FIG. In addition, a drying hood 14 is provided above the solvent vapor reservoir 11 in order to prevent the influence of the flow of external air. Here, when the discharge port 12 is not provided, or when the discharge port 12 is installed in the middle of the recycle pipe 8 lower than the coating tank liquid level 10 as in JP-A-8-220786, a methylene chloride solvent having a high saturated vapor pressure. When a coating film of 100 μm or more that releases a large amount of solvent vapor is formed, the solvent vapor concentration in the solvent vapor reservoir 11 cannot be sufficiently discharged, and the solvent vapor stays around the cylindrical substrate, and the cylinder The coating film formed on the substrate 9 is caused to have uneven touch drying, and the leading thin film is increased. However, in the present invention, since the discharge port 12 for discharging the solvent vapor is provided at a position higher than the coating tank liquid level 10 above the solvent vapor reservoir chamber, even if a solvent having a high saturated vapor concentration is used, it is cylindrical. It is possible to uniformly discharge the solvent vapor around the substrate, and the effect can prevent the occurrence of film thickness unevenness and increase of the leading thin film.
[0032]
FIG. 3 shows a schematic configuration of an example of the multiple simultaneous dip coating apparatus of the present invention, and shows a state in the middle of pulling up the cylindrical substrate from the coating tank. The coating liquid 1 is pumped by the pump 4 from the coating liquid tank 2 through the supply pipe 3 and is supplied into the coating tank 6 through the filter 5. The coating tank 6 has a mesh 15 inserted in the lower part in order to obtain a uniform coating solution flow rate in the tank. The coating liquid supplied into the coating tank 6 overflows, is collected in the continuous coating liquid receiving tank 7 at the lower end of the solvent vapor reservoir 11 installed in the upper part of the coating tank 6, and flows out to the recycling pipe 8. Collected in the liquid tank 2. When dip coating is performed using this dip coating apparatus, when the cylindrical substrate 9 is immersed in the coating tank 6 and then pulled up, it always overflows for the purpose of keeping the coating tank liquid level 10 constant. The coating liquid is circulated by a circulation means. Further, a solvent vapor reservoir chamber is installed above the coating tank, and a drying hood is further provided on the solvent vapor reservoir chamber. A discharge port 12 for discharging the solvent vapor is provided between the solvent vapor storage chamber and the drying hood. The discharge port 12 is provided at a position higher than the coating tank liquid level 10.
[0033]
In the case of applying a large number of drying hoods, it is possible to install on the solvent vapor reservoir chamber with the same outer wall structure as the solvent vapor reservoir chamber. In order to keep it constant, it is preferable to install a drying hood independently on each cylindrical substrate. FIG. 3 shows an example in which a drying hood is installed independently on each of a large number of cylindrical substrates.
[0034]
The drying hood is preferably provided with a large number of vents for discharging solvent vapor during drying. The opening area ratio of the entire vent is preferably 5 to 70% with respect to the entire area of the dry hood. If it is less than 5%, the solvent vapor is not sufficiently discharged, and if it exceeds 70%, it is difficult to adjust the drying rate.
[0035]
In the present invention, as the cylindrical substrate, a known conductive material used in an electrophotographic photosensitive member is used. In addition, any known material can be used as the photosensitive member-forming coating solution applied to the cylindrical substrate. For example, an undercoat layer coating solution, a charge generation layer coating solution, a charge transport layer coating solution, or the like is used, thereby forming an undercoat layer, a charge generation layer, and a charge transport layer, which are photoreceptor constituent layers. However, it is also possible to use a coating solution for forming other photosensitive layer constituting layers such as an intermediate layer and a surface layer.
[0036]
Generally as a solvent used for this invention, most will be included if it is an organic solvent used for the coating liquid for organic photosensitive layer formation. Specific examples include halogenated hydrocarbons such as methylene chloride, alcohols such as ethyl alcohol, and ketones such as cyclohexanone.
[0037]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
[0038]
Example 1
An intermediate layer was formed on the cylindrical substrate as follows.
[0039]
An intermediate layer coating solution 1 was prepared by adding 1 part by mass of polyamide resin CM8000 (manufactured by Toray Industries, Inc.) and 10 parts by mass of methanol to the same container and dissolving and dispersing them. The intermediate layer coating solution was applied onto a cylindrical aluminum substrate (1.0 mmt × 30 mmφ × 340 mm) using the dip coating apparatus of FIG. The coating solution temperature at that time was 24 ° C. The speed at which the aluminum substrate was pulled up from the coating solution was 480 mm / min. The position of the discharge port 12 is set with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 1 L / min, and the diameter of the recycle pipe 8 was 100 mmφ. The coated substrate was air-dried through a 15 cm drying hood, then placed in a dryer and dried by heating at 70 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.1 μm.
[0040]
Next, 60 g of Y-type titanyl phthalocyanine, 700 g of silicone-modified butyral resin (manufactured by Shin-Etsu Chemical Co., Ltd.), and 2000 ml of 2-butanone were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied on the aluminum substrate on which the intermediate layer obtained in Example 1 was formed using the dip coating apparatus of FIG. The speed at which the aluminum substrate was pulled up from the coating solution was 480 mm / min. The coating solution temperature at that time was 24 ° C. The position of the discharge port 12 is set with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 1 L / min, and the diameter of the recycle pipe 8 was applied under the conditions of an inner diameter of 100 mmφ.
[0041]
Next, a charge transport layer was formed on the charge generation layer formed as described above. 225 g of charge transport material [N- (4-methylphenyl) -N- {4- (β-phenylstyryl) phenyl} -p-toluidine], 300 g of polycarbonate (viscosity average molecular weight 20,000), antioxidant (exemplary compound) 1-3) 6 g and 2000 ml of dichloromethane were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm. The speed at which the aluminum substrate was pulled up from the coating solution was 240 mm / min. The coating solution temperature at that time was 24 ° C. The position of the discharge port 12 is set with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 1 L / min, and the diameter of the recycle pipe was 100 mmφ. The coated aluminum substrate was air-dried via a 15 cm drying hood, then placed in a dryer and heated and dried at 90 ° C. for 60 minutes to form a charge transport layer, thereby producing an electrophotographic photosensitive drum. Under these conditions, coating was repeated four times. Table 3 shows the film thickness unevenness values. The film thickness unevenness value is a difference between the maximum value and the minimum value of the film thickness values of 16 points in total in the circumferential direction (90 ° interval) at each of 20 mm, 50 mm, 160 mm, and 300 mm from the upper end of the coating film. Here, the saturated vapor pressure of dichloromethane at 24 ° C. was about 46.6 kPa, and the specific gravity with respect to air was about 1.326.
[0042]
Comparative Example 1
For comparison, charge transport is performed on the charge generation layer under the same conditions as in Example 1 except that the discharge port is attached in the middle of the recycle pipe 8 positioned below the coating liquid surface as shown in FIG. The layer was applied. The results are shown in Table 1.
[0043]
[Table 1]

[0044]
Example 2
Using the intermediate layer coating solution used in Example 1, coating was performed using the four simultaneous coating apparatus shown in FIGS. 3 and 5 (FIG. 5 is a diagram of a method of arranging the four simultaneous coating substrates). . The speed at which the cylindrical aluminum substrate was pulled up from the coating solution was 400 mm / min, and the coating temperature at this time was 24 ° C. As the position of the discharge port 12, it is installed with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 5 L / min, and the diameter of the recycle pipe was 150 mmφ. The coated aluminum substrate was air-dried via a 15 cm drying hood, then placed in a dryer and dried by heating at 70 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.1 μm.
[0045]
Next, the charge generation layer coating solution was applied onto the aluminum substrate on which the intermediate layer was formed, using the four simultaneous coating apparatus shown in FIGS. The speed at which the aluminum substrate was pulled up from the coating solution was 480 mm / min. The coating temperature at this time was 24 ° C. As the position of the discharge port 12, it is installed with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 5 L / min, and the diameter of the recycle tube was 150 mmφ. The coated aluminum substrate was air-dried via a 15 cm drying hood, and then a charge generation layer (dried film thickness of 0.5 μm) of finger touch drying (a dry state where it was not sticky even when touched with a finger) was formed.
[0046]
On the charge generation layer, the same charge transport layer coating solution as that used in Example 1 was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm. The speed at which the aluminum substrate was pulled up from the coating solution was 240 mm / min, and the number of simultaneous coatings was four. The coating temperature at this time was 24 ° C. As the position of the discharge port 12, it is installed with a gap width of 1 mm between the solvent vapor storage chamber and the drying hood shown in FIG. The outlet is formed in a circle of 50 mm at a height of 10 cm from the liquid level of the coating tank. The coating liquid circulation flow rate was 5 L / min, and the diameter of the recycle pipe was 150 mmφ. The coated aluminum substrate was air-dried via a 15 cm drying hood, then placed in a dryer and heat-dried at 90 ° C. for 60 minutes to form a charge transport layer, thereby producing an electrophotographic photosensitive drum. Table 6 shows the film thickness unevenness value of each of the four. Here, the film thickness unevenness values are the maximum value and the minimum value of the film thickness values of 4 points in the circumferential direction (at intervals of 90 °) of each of 20 mm, 50 mm, 160 mm, and 300 mm from the upper end of the coating film, a total of 16 points It is a difference. The results are shown in Table 2.
[0047]
Comparative Example 2
For comparison, the charge transport layer was coated on the charge generation layer under the same conditions as in Example 2 except that the discharge port was attached in the middle of the recycle pipe 8 positioned below the coating liquid surface. The results are shown in Table 2.
[0048]
Example 3
Table 2 shows the results of applying the charge transport layer on the charge generation layer under the same conditions as in Example 2 except that the interval width of the discharge port 12 was set to 8 mm.
[0049]
Example 4
A charge transport layer was applied on the charge generation layer under the same conditions as in Example 2 except that the interval width of the discharge port 12 was 0.2 mm. The results are shown in Table 2.
[0050]
The leading thin film was evaluated for each of the photoreceptors of Examples 2 to 4 and Comparative Example 2. The results are shown in Table 3.
* Evaluation of top thin film
One straight line is arbitrarily selected along the drum axis of the cylindrical photoconductor. The film thickness of the photosensitive layer is measured at an equal interval of 10 mm from the top of the linear coating, and a photoconductor film thickness profile as shown in FIG. 4 is produced. The length L of the leading thin film is defined as a length a from the leading edge of the drum of the photosensitive member to the intersection of the leading film thickness rising and the saturation film extension war. The length of the leading thin film was measured for each photoconductor, and the results are shown in Table 3. The film thickness measuring device was a light detecting film thickness measuring device MCPD-1000 (instant multi-photometric detector: Otsuka Electronics Co., Ltd.).
[0051]
[Table 2]

[0052]
[Table 3]

[0053]
As can be seen from Tables 1, 2 and 3, the electrophotographic photosensitive member of the present invention is provided with a solvent vapor distillation chamber above the coating tank and a solvent vapor discharge port provided between the solvent vapor distillation chamber and the drying hood. Compared with the coating apparatus in which the solvent vapor discharge port is provided in the middle of the conventional recycling pipe shown in the comparative example, the coating apparatus in either the film thickness unevenness after coating the charge transport layer or the length of the leading thin film There is also a significant improvement effect.
[0054]
【The invention's effect】
As is clear from the above-described examples, when the electrophotographic photoreceptor coating apparatus and coating method of the present invention are used, the photosensitive layer formed on each cylindrical substrate has small film thickness unevenness and the length of the leading thin film. It is possible to provide a cylindrical electrophotographic photosensitive member that can be manufactured in a short length and therefore has good performance.
[Brief description of the drawings]
FIG. 1 is a view of a coating apparatus in which a solvent vapor outlet is provided in the middle of a recycling pipe and at a position lower than the liquid level of a coating tank.
FIG. 2 is a diagram showing a schematic configuration of an example of a single-shot dip coating apparatus according to the present invention.
FIG. 3 is a diagram showing a schematic configuration of an example of a multiple simultaneous dip coating apparatus of the present invention.
FIG. 4 is a view showing a film thickness profile of a photoreceptor coated with a charge transport layer.
FIG. 5 is a diagram of a method for arranging four substrates simultaneously applied.
[Explanation of symbols]
1 Coating liquid
2 Coating liquid tank
3 Supply piping
4 Pump
5 Filter
6 Application tank
7 Coating solution receiving tank
8 Recycle pipe
9 Cylindrical substrate
10 Coating tank liquid level (overflow surface)
11 Solvent vapor chamber
12 Discharge port
14 Dry food
15 mesh

Claims

In an electrophotographic photosensitive member coating apparatus in which a cylindrical substrate is immersed in a coating solution and pulled up to form a coating film on the cylindrical substrate, the coating device includes a coating tank for storing the coating solution, and the coating tank. A solvent vapor reservoir chamber provided, and a drying hood provided above the solvent vapor reservoir chamber, the solvent vapor reservoir chamber covering the entire upper surface of the coating tank, and between the solvent vapor reservoir chamber and the drying hood above it. And an exhaust port that is located above the solvent vapor reservoir and that exhausts the solvent vapor having a gap width of 0.2 to 8 mm outside the system so as to surround the cylindrical substrate. Photoconductor coating device.

2. The electrophotographic photosensitive member coating apparatus according to claim 1, wherein the discharge port is formed with an opening ratio of 50 to 100% of the peripheral length of the dry hood.

The electrophotographic photosensitive member coating apparatus according to claim 1, wherein a recycling pipe is connected to the solvent vapor storage chamber, and the overflowing coating liquid is collected and circulated by the recycling pipe.

The electrophotographic photosensitive member coating method using the electrophotographic photosensitive member coating apparatus according to any one of claims 1 to 3, wherein the coating film is formed on the cylindrical substrate while discharging the solvent vapor from the discharge port. A method for applying an electrophotographic photosensitive member, wherein:

5. The electrophotographic photosensitive member coating method according to claim 4, wherein dip coating is performed on the cylindrical substrate so that the coating film thickness is 30 to 300 [mu] m.

6. The electrophotographic photoreceptor coating method according to claim 4, wherein a solvent having a saturated vapor pressure (24 [deg.] C.) of 6.5 to 80 kPa is used as the solvent for the coating solution.

The electrophotographic photoreceptor coating method according to claim 4, wherein a plurality of cylindrical substrates are simultaneously immersed in a coating solution and pulled to form a coating layer.

The coating method for an electrophotographic photosensitive member according to claim 4, wherein the coating solution is a coating solution for forming a charge transport layer.