JP4175453B2

JP4175453B2 - Electrophotographic photosensitive member coating apparatus, coating method, and electrophotographic photosensitive member

Info

Publication number: JP4175453B2
Application number: JP2001246530A
Authority: JP
Inventors: 信昭小林
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2001-08-15
Filing date: 2001-08-15
Publication date: 2008-11-05
Anticipated expiration: 2021-08-15
Also published as: JP2003057854A

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及び該塗布装置を用いた電子写真感光体の塗布方法、該塗布方法により作製された電子写真感光体に関するものであり、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浸漬塗布を用いた塗布装置、該塗布装置を用いた塗布方法、及び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剤蒸気や、塗布槽液面から発生する溶剤蒸気の影響により、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、あるいは一本の円筒状基体内で不均一となり、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、円筒状基体が液体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剤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、液受け槽近傍に溶剤蒸気排出口を設け、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剤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剤蒸気排出口近辺の円筒状基体の周辺では、溶剤蒸気濃度は低いが、離れた箇所のそれは高くなり、溶剤蒸気濃度の均一化をはかることは困難であった。
【０００５】
特に、多数本の円筒状基体を同時に塗布する装置では、円筒状基体毎にその周辺の溶媒蒸気濃度が不均一になりやすく、各基体間で乾燥速度が異なり、膜厚むらや先頭薄膜が増大した感光体が出現し、生産性が低下する原因となっていた。
【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号に示されるように、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、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剤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、その結果塗布先端の塗布膜が薄くなる先頭薄膜が大きくなったり、膜厚むらを発生しやすい。特に、塗布膜厚が薄い電荷発生層等では膜厚むら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、多数本の円筒状基体を同時に引上げた時に形成される塗布膜から発生する溶剤蒸気、および塗布槽液面から蒸発する溶剤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剤を用いても、均一に溶媒を排出でき、且つ乾燥膜厚が１μｍ以下の電荷発生層等を塗布しても膜厚むらが小さ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、円筒状基体上に、浸漬塗布法によって膜厚むらのない感光層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にあり、該塗布方法を用いて形成された電子写真感光体を提供することである。
【０００８】
【課題を解決するための手段】
本発明の目的は以下の構成を取ることにより達成される。
【０００９】
１．１つの塗布槽中の塗布液に複数本の円筒状基体を同時に浸漬し、引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、塗布槽の上に溶媒蒸気溜室とその上にそれぞれの円筒状基体に対応した乾燥フードを備え、前記溶媒蒸気溜室と乾燥フードの間に０．１〜１０ｍｍの間隙幅を有する排気口を有することを特徴とする電子写真感光体の塗布装置。
【００１０】
２．前記乾燥フードは円筒状基体通過時のフードと円筒状基体間の隙幅が該円筒状基体の直径比で１／１０〜１に構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。
【００１１】
３．前記乾燥フードが多数の通気孔を有す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。
【００１２】
４．前記通気孔の１つの開口径が０．１〜１０ｍｍφであることを特徴とする前記３に記載の電子写真感光体の塗布装置。
【００１３】
５．前記通気孔全体の開口面積比（乾燥フード全体の面積に対して）が５〜５０％であることを特徴とする前記３又は４に記載の電子写真感光体の塗布装置。
【００１４】
６．前記１〜５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て、複数本の円筒状基体を同時に塗布液に浸漬し、引き上げて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。
【００１５】
７．前記電子写真感光体の塗布膜厚が５〜３００μｍであることを特徴とする前記６に記載の電子写真感光体の塗布方法。
【００１６】
８．塗布液が電荷発生層形成用塗布液であることを特徴とする前記６又は７に記載の電子写真感光体の塗布方法。
【００１８】
以下、本発明を詳細に説明する。
図１は本発明の多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、円筒状基体を塗布液から引上げ途中の状態を示すものである。図１において、塗布槽６の上には外部のエアー流れの影響を防止するための溶媒蒸気溜室１１を有しており、該溶媒蒸気溜室１１の上部に個別の乾燥フード１４が設けられている。円筒状基体は塗布槽６から引き上げられると、溶媒蒸気溜室１４に入り、ここで塗布膜が大量の溶媒蒸気を放出し、個別の乾燥フード１４に送られ乾燥される。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。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溶媒蒸気溜室１１内の溶媒蒸気濃度を全体に均一に維持することができ、塗布膜の指触乾燥むらを発生させない。
【００１９】
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。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。又、乾燥フードは円筒状基体を取り囲む構造を有する。
【００２０】
一方、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の上部の溶媒蒸気溜室１１の下端部に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循環手段によって塗布液を循環する。
【００２１】
従来、多数本の円筒状基体を同時に塗布する場合、塗布液層６の上に設けられる乾燥フードは図２の如く、溶媒蒸気溜室を乾燥フードと兼用した構造、即ち、多数本基体の全部を大型の乾燥フード１４（以下、大型乾燥フードとも云う）で囲んだ構造の装置が用いられていたが、この構造では乾燥フード１４の中の溶媒蒸気濃度が均一に低下しにくく、各基体の周辺の溶媒蒸気濃度を均一に低下させるのが難しく、膜厚むらや先頭薄膜の増大を引き起こしがちであった。
【００２２】
本発明では図１の如く、溶媒蒸気溜室と乾燥フードを分離し、乾燥フードを個別の円筒状基体毎に設けることにより、各円筒状基体間の乾燥条件を均一にし、且つ乾燥フード内の溶媒蒸気濃度を均一に低下させることにより、膜厚むらや先頭薄膜の増大を防止し、各感光体間の特性ばらつきを小さくすることが出来る。
【００２３】
上記乾燥フードは円筒状基体を通過させるに十分な円筒状の形態を有することが好ましい。即ち、乾燥フードのフードと円筒状基体間の間隙幅が該円筒状基体直径比で１／１０〜１に構成することが好ましい。該直径比が１／１０未満の場合は円筒状基体の通過に際して、乾燥フードと基体が接触し、塗布膜を削る等の障害が出やすく、一方、直径比を１より大きくしても、装置が大型になるだけで、生産性の向上には寄与しない。通気孔１つの開口径は、０．１〜１０ｍｍが好ましい。０．１ｍｍ未満だと乾燥フード中に溶媒蒸気が滞留しやすく、１０ｍｍより大きいと乾燥フード内が外気により攪乱されやすい。
【００２４】
又、乾燥フードには多数の通気孔を有することが好ましい。該通気口の全体の開口面積比（乾燥フード全体の面積に対して）は５〜５０％であることが好ましい。５％未満では乾燥フード中に溶媒蒸気が滞留しやすく、５０％より大きいと乾燥フード内の環境が外気により、攪乱されやすい。
【００２５】
又、乾燥フードの長さは５〜３００ｃｍ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。
【００２６】
本発明は乾燥フードの下、塗布槽の上に溶媒蒸気溜室を有するが、乾燥フードの塗布液面からの距離は１〜１００ｃｍの間が好ましい。即ち、１ｃｍ未満では溶媒蒸気溜室の空間が狭くなり、塗布直後の塗布膜を安定させることが出来ない。又、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。
【００２７】
又、本発明は溶媒蒸気溜室と乾燥フードの間に排気口を設ける。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、塗布直後の乾燥速度を感光体間、或いは基体の円周方向による膜厚むらを小さくする事が出来る。
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。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。
【００２８】
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。
【００２９】
前記乾燥フードの乾燥条件は自然乾燥が好ましい。該乾燥フード内の塗布膜は塗布直後の状態であるので、強制的に乾燥風を送り込むと、却って膜厚むらや、先頭薄膜を増加させる。
【００３０】
また、複数の円筒状基体の外周面に同時に塗膜を形成させるのに、各基体の塗布乾燥条件を均一にすることが好ましく、お互いの円筒状基体の配列位置に差が出ない配列方法が好ましい。このような基体の配列方法としては、図３に図示した４本同時塗布装置の配列方法が好ましい。
【００３１】
以上、本発明の装置を用いて多数本の円筒状基体に浸漬塗布することにより、浸漬塗布直後の指触乾燥の条件を個々の基体間で均一に保ちながら溶媒を系外に排出ができる。その結果、塗布膜厚（塗布直後の溶媒を含んだ塗布膜厚）が３０〜３００μｍの広い範囲で膜厚むらを小さくできる。
【００３２】
又、飽和蒸気圧が０．７〜８０ｋＰａの広い範囲から溶媒を選択しても、膜厚むらの改良効果を持続することが出来る。
【００３３】
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。
【００３４】
本発明において用いられる塗布液溶剤としては、一般的に、有機感光層形成用塗布液に使用される有機溶剤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、テトラヒドロフランのようなエーテル、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。
【００３５】
【実施例】
以下、本発明を実施例によって具体的に説明する。
【００３６】
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。
【００３７】
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１の独立した乾燥フード（各乾燥フードには多数の３ｍｍφの通気口があり、通気孔の開口面積比は２５％）を有する４本同時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１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８の径は、内径１５０ｍｍφとした。塗布した各基体は１５ｃｍの各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。４本それぞれの膜厚むら値を表１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。２４℃におけるメタノールの飽和蒸気圧は１６〜１８．７ｋＰａであった。
【００３８】
比較例１
比較のために、図２記載のように大型乾燥フードを用いた塗布装置にした以外は、実施例１と同一の条件で中間層の塗布操作を行った。その結果を表１に示す。
【００３９】
【表１】

【００４０】
尚、膜厚測定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。
【００４１】
実施例２
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１の独立した乾燥フード（各乾燥フードには多数の３ｍｍφの通気口があり、通気孔の開口面積比は２５％）を有する４本同時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、７０℃において１０分間乾燥し、膜厚０．２μｍの電荷発生層を形成した。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１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８の径は内径１５０ｍｍφとした。４本それぞれの膜厚むら値を表２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。ここで２４℃における２−ブタノンの飽和蒸気圧は、約２．３ｋＰａであり、空気に対する比重は、約０．８１であった。
【００４２】
比較例２
比較のために、図２記載のように大型乾燥フードを用いた以外は、実施例２と同一の条件で前記中間層上に電荷発生層の塗布操作を行った。その結果を表２に示す。
【００４３】
【表２】

【００４４】
実施例３
実施例２において、排気口の間隔幅１ｍｍを８ｍｍに変更した以外は同様にして、前記中間層上に電荷発生層を塗布した。その結果、各基体の膜厚偏差は実施例２とほぼ同様の結果が得られた。
【００４５】
実施例４
実施例２において排気口の間隔幅１ｍｍを０．２ｍｍに変更した以外は同様にして、前記中間層上に電荷発生層を塗布した。その結果、各基体の膜厚偏差は実施例２とほぼ同様の結果が得られた。
【００４６】
表１、表２から、複数本の円筒状基体を同時に塗布液に浸漬する塗布槽の上に複数本の円筒状基体に対応した独立フードを設けた塗布装置を用いて形成した中間層及び電荷発生層は、比較の大型乾燥フードを用いた場合に比し、著しく膜厚むらが改善されていることが見いだされる。
【００４７】
又、これらの実施例１〜４及び比較例１、２の各電荷発生層上に乾燥膜厚２０μｍの電荷輸送層を浸漬塗布して、電子写真感光体を作製した。これらの電子写真感光体を市販の電子写真方式のプリンターに搭載し、ハーフトーン画像を形成し、画像評価を行った。その結果、実施例１〜４から作製した電子写真感光体を用いた画像評価ではどの感光体を用いても画像むらのない、良好なハーフトーン画像が得られたが、比較例１、２から得られた電子写真感光体を用いた画像評価ではハーフトーン画像に画像むらが発生していた。
【００４８】
【発明の効果】
上記の実施例から明らかなように、独立した乾燥フードを有する本発明の電子写真感光体の塗布装置を用いることにより、各円筒状基体に形成された感光層あるいは中間層の膜厚は、全ての円筒状基体で均一性が高く作製することができ、その結果良好な円筒状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】本発明の多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２】大型乾燥フードを用いた塗布装置の図である。
【図３】４本同時塗布装置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
The present invention relates to an electrophotographic photosensitive member coating apparatus, an electrophotographic photosensitive member coating method using the coating apparatus, and an electrophotographic photosensitive member produced by the coating method, and particularly in the production of an electrophotographic photosensitive member. The present invention relates to a coating apparatus using dip coating for forming an organic photosensitive layer on the outer peripheral surface of a cylindrical substrate, a coating method using the coating apparatus, and an electrophotographic photosensitive member.
[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 photoconductive materials 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 narrowed, the productivity is further increased, which is advantageous. In this case, the vapor 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 solvent vapor, the drying speed of the coating film formed on the cylindrical substrate becomes nonuniform between each cylindrical substrate or within a single cylindrical substrate, resulting in uneven film thickness. End up. As a workaround, as described in JP-A-59-127049, etc., when the cylindrical substrate is not pulled up from the liquid level, air is sent from the outside to the vicinity of the liquid receiving tank to receive the liquid. The solvent vapor concentration is reduced in advance from the vicinity of the tank, and the touch drying speed is accelerated. As described in JP-A-3-151, etc., a solvent vapor outlet is provided in the vicinity of the liquid receiving tank. It is connected to a forced exhaust device provided with a -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 the solvent vapor concentration is high in the distant place. It was difficult to achieve uniformization.
[0005]
In particular, in an apparatus that applies a large number of cylindrical substrates at the same time, the solvent vapor concentration in the periphery of each cylindrical substrate tends to be non-uniform, the drying speed varies among the substrates, and the film thickness unevenness and the leading thin film increase. As a result, the photoconductor appeared, which caused the productivity to decrease.
[0006]
As a workaround for the non-uniformity of the solvent vapor concentration, for example, as shown in JP-A-8-220786, a solvent vapor discharge port is provided in the middle of the recycling pipe and at a position lower than the liquid level of the coating tank, A method has been proposed in which the solvent vapor concentration on the liquid surface of the coating layer is made uniform using a solvent having a specific gravity heavier than air and a relatively low saturated vapor concentration. 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 non-sticky when touched with a finger). As a result, the leading thin film in which the coating film at the coating tip becomes thin becomes large, and the film thickness unevenness tends to occur. In particular, in a charge generation layer or the like having a thin coating film thickness, film thickness unevenness tends to occur.
[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 make the solvent vapor generated from the coating film formed when simultaneously pulling up a large number of cylindrical substrates and the solvent vapor evaporated from the coating tank surface as uniform as possible around the cylindrical substrate. Even if a solvent such as methylene chloride having a high saturated vapor concentration is discharged, the solvent can be discharged uniformly, and even if a charge generation layer having a dry film thickness of 1 μm or less is applied, the electrophotographic photosensitive is small The object is to provide a body applicator. Another object of the present invention is to provide a coating method for an electrophotographic photosensitive member capable of forming a photosensitive layer having no film thickness unevenness on a cylindrical substrate by a dip coating method. It is an object to provide an electrophotographic photoreceptor formed in the above manner.
[0008]
[Means for Solving the Problems]
The object of the present invention is achieved by taking the following constitution.
[0009]
1. In an electrophotographic photosensitive member coating apparatus in which a plurality of cylindrical substrates are simultaneously immersed in a coating solution in a single coating tank and pulled to form a coating film on the cylindrical substrate, a solvent vapor reservoir is formed on the coating tank. An electrophotography comprising a chamber and a drying hood corresponding to each of the cylindrical substrates on the chamber, and having an exhaust port having a gap width of 0.1 to 10 mm between the solvent vapor storage chamber and the drying hood. Photoconductor coating device.
[0010]
2. 2. The electrophotographic apparatus according to 1 above, wherein the dry hood has a gap width between the hood and the cylindrical substrate when passing through the cylindrical substrate of 1/10 to 1 in terms of a diameter ratio of the cylindrical substrate. Photoconductor coating device.
[0011]
3. 3. The electrophotographic photosensitive member coating apparatus as described in 1 or 2 above, wherein the dry hood has a large number of ventilation holes.
[0012]
4). 4. The electrophotographic photosensitive member coating apparatus as described in 3 above, wherein one opening diameter of the vent hole is 0.1 to 10 mmφ.
[0013]
5. 5. The electrophotographic photosensitive member coating apparatus according to 3 or 4 above, wherein an opening area ratio of the whole vent hole (relative to an area of the entire dry hood) is 5 to 50%.
[0014]
6). Using the electrophotographic photoreceptor coating apparatus according to any one of 1 to 5 above, a plurality of cylindrical substrates are simultaneously immersed in a coating solution and pulled up to form a coating film on the cylindrical substrate. A method for applying an electrophotographic photosensitive member.
[0015]
7). 7. The method for coating an electrophotographic photosensitive member according to 6, wherein the electrophotographic photosensitive member has a coating thickness of 5 to 300 μm.
[0016]
8). 8. The method for coating an electrophotographic photosensitive member according to 6 or 7, wherein the coating liquid is a coating liquid for forming a charge generation layer.
[0018]
Hereinafter, the present invention will be described in detail.
FIG. 1 shows a schematic configuration of an example of a multiple simultaneous dip coating apparatus of the present invention, and shows a state in the middle of pulling up a cylindrical substrate from a coating solution. In FIG. 1, a solvent vapor reservoir chamber 11 for preventing the influence of an external air flow is provided on the coating tank 6, and an individual drying hood 14 is provided above the solvent vapor reservoir chamber 11. ing. When the cylindrical substrate is pulled up from the coating tank 6, it enters the solvent vapor reservoir chamber 14 where the coating film releases a large amount of solvent vapor and is sent to an individual drying hood 14 to be dried. In the present invention Ru provided an outlet 12 between the solvent vapor reservoir 11 and the drying hood 14. By providing the discharge port 12, the solvent vapor concentration in the solvent vapor reservoir 11 can be maintained uniformly even when a solvent having a high saturation vapor pressure is used as the coating liquid, and unevenness of the coating film to the touch is uneven. Does not occur.
[0019]
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 discharge port is formed between the solvent vapor storage chamber and the drying hood so as to surround the cylindrical substrate when the coated substrate is pulled up. The drying hood has a structure surrounding the cylindrical substrate.
[0020]
On the other hand, 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 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 coating liquid receiving tank 7 provided at the lower end of the solvent vapor reservoir 11 at the top of the coating tank 6, and flows out into the recycling pipe 8. It is collected in the 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.
[0021]
Conventionally, when a large number of cylindrical substrates are applied simultaneously, the drying hood provided on the coating solution layer 6 has a structure in which the solvent vapor reservoir chamber is also used as the drying hood as shown in FIG. However, in this structure, the concentration of the solvent vapor in the dry hood 14 is difficult to be reduced uniformly, and each substrate has a structure in which the substrate is surrounded by a large dry hood 14 (hereinafter also referred to as a large dry hood). It was difficult to uniformly reduce the concentration of the solvent vapor in the surrounding area, which tended to cause uneven film thickness and increase of the leading thin film.
[0022]
In the present invention, as shown in FIG. 1, the solvent vapor storage chamber and the drying hood are separated, and a drying hood is provided for each individual cylindrical substrate, so that the drying conditions between the cylindrical substrates are uniform, and the drying hood is By uniformly reducing the solvent vapor concentration, it is possible to prevent unevenness of the film thickness and increase of the leading thin film, and to reduce variation in characteristics between the photoconductors.
[0023]
The dry hood preferably has a cylindrical shape sufficient to allow the cylindrical substrate to pass through. That is, it is preferable that the gap width between the hood of the dry hood and the cylindrical substrate is 1/10 to 1 in terms of the cylindrical substrate diameter ratio. When the diameter ratio is less than 1/10, the dry hood and the substrate come into contact with each other when passing through the cylindrical substrate, and obstacles such as scraping of the coating film are likely to occur. Will only contribute to the improvement of productivity. The opening diameter of one ventilation hole is preferably 0.1 to 10 mm. If it is less than 0.1 mm, the solvent vapor tends to stay in the dry hood, and if it is more than 10 mm, the inside of the dry hood is easily disturbed by the outside air.
[0024]
The dry hood preferably has a large number of vent holes. The opening area ratio of the entire vent (relative to the entire area of the dry hood) is preferably 5 to 50%. If it is less than 5%, the solvent vapor tends to stay in the dry hood, and if it is more than 50%, the environment in the dry hood is likely to be disturbed by outside air.
[0025]
The length of the dry hood is preferably 5 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.
[0026]
Under the present invention is drying hood, but that have a solvent vapor reservoir above the coating tank, the distance from the coating liquid surface of the drying hood is preferably between 1 to 100 cm. That is, if it is less than 1 cm, the space of the solvent vapor reservoir chamber becomes narrow, and the coating film immediately after coating cannot be stabilized. Moreover, even if it is larger than 100 cm, an effect commensurate with the increase in size of the apparatus cannot be obtained.
[0027]
Further, the present invention is an exhaust port Ru provided between drying hood with solvent vapor reservoir chambers. By exhausting the solvent vapor from the exhaust port, the concentration of the solvent vapor in the entire solvent vapor reservoir chamber can be made uniform, and the drying speed immediately after coating can be reduced between the photoconductors or the film thickness unevenness in the circumferential direction of the substrate. I can do it .
The outlet 12 is you placed in gap width 0.1~10mm during the drying hood with solvent vapor reservoir chambers. 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.
[0028]
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.
[0029]
The drying condition of the drying hood is preferably natural drying. Since the coating film in the drying hood is in a state immediately after coating, when the drying air is forcibly sent, the film thickness unevenness and the leading thin film are increased.
[0030]
Further, in order to form a coating film on the outer peripheral surfaces of a plurality of cylindrical substrates at the same time, it is preferable that the coating and drying conditions of each substrate are uniform, and there is an arrangement method in which there is no difference between the arrangement positions of the cylindrical substrates. preferable. As a method for arranging such substrates, the method for arranging four simultaneous coating apparatuses shown in FIG. 3 is preferable.
[0031]
As described above, by dip-coating a large number of cylindrical substrates using the apparatus of the present invention, the solvent can be discharged out of the system while maintaining the touch-drying conditions immediately after dip coating between the individual substrates. As a result, the film thickness unevenness can be reduced in a wide range of the coating film thickness (coating film thickness including the solvent immediately after coating) of 30 to 300 μm.
[0032]
Even if the solvent is selected from a wide range of saturated vapor pressure of 0.7 to 80 kPa, the effect of improving the film thickness unevenness can be maintained.
[0033]
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.
[0034]
In general, the coating solution solvent used in the present invention includes almost all organic solvents used in coating solutions for forming an organic photosensitive layer. Specific examples include halogenated hydrocarbons such as methylene chloride, ethers such as tetrahydrofuran, alcohols such as ethyl alcohol, and ketones such as cyclohexanone.
[0035]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
[0036]
Example 1
An intermediate layer was formed on the cylindrical substrate as follows.
[0037]
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 is formed into a cylinder using the four simultaneous dip coating apparatus having independent drying hoods shown in FIG. 1 (each drying hood has a large number of 3 mmφ vents and the opening area ratio of the vents is 25%). It was applied on a glass-like aluminum substrate (1.0 mmt × 30 mmφ × 340 mm). 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 5 L / min, and the diameter of the recycle pipe 8 was 150 mmφ. Each coated substrate was air-dried through a 15 cm drying hood, then placed in a dryer and heat-dried at 70 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.1 μm. Table 1 shows the film thickness unevenness value of each of the four films. 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, and a total of 16 points. It is a difference. The saturated vapor pressure of methanol at 24 ° C. was 16 to 18.7 kPa.
[0038]
Comparative Example 1
For comparison, the intermediate layer was coated under the same conditions as in Example 1 except that the coating apparatus used a large dry hood as shown in FIG. The results are shown in Table 1.
[0039]
[Table 1]

[0040]
The film thickness was measured using a photodetection type film thickness meter MCPD-1000 (instant multi-photometer detector: Otsuka Electronics Co., Ltd.).
[0041]
Example 2
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 carried out using the four simultaneous dip coating apparatus having independent drying hoods shown in FIG. 1 (each drying hood has a number of 3 mmφ vents and the opening area ratio of the vents is 25%). The intermediate layer obtained in Example 1 was coated on the aluminum substrate and dried at 70 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 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 5 L / min, and the diameter of the recycle pipe 8 was 150 mmφ. Table 2 shows the film thickness unevenness value of each of the four films. The film thickness unevenness value is the difference between the maximum value and the minimum value of the film thickness values of a total of 16 points at four points (90 ° intervals) in the circumferential direction at 20 mm, 50 mm, 160 mm, and 300 mm from the upper end of the coating film. . Here, the saturated vapor pressure of 2-butanone at 24 ° C. was about 2.3 kPa, and the specific gravity with respect to air was about 0.81.
[0042]
Comparative Example 2
For comparison, a charge generation layer was coated on the intermediate layer under the same conditions as in Example 2 except that a large dry hood was used as shown in FIG. The results are shown in Table 2.
[0043]
[Table 2]

[0044]
Example 3
In Example 2, a charge generation layer was coated on the intermediate layer in the same manner except that the interval width of the exhaust port 1 mm was changed to 8 mm. As a result, the film thickness deviation of each substrate was almost the same as in Example 2.
[0045]
Example 4
A charge generation layer was applied on the intermediate layer in the same manner as in Example 2 except that the interval width of the exhaust port 1 mm was changed to 0.2 mm. As a result, the film thickness deviation of each substrate was almost the same as in Example 2.
[0046]
From Tables 1 and 2, the intermediate layer formed by using a coating apparatus provided with an independent hood corresponding to a plurality of cylindrical substrates on a coating tank in which a plurality of cylindrical substrates are immersed in a coating solution at the same time, and charge The generation layer is found to have significantly improved film thickness unevenness as compared to the case of using a comparative large-sized dry hood.
[0047]
Further, an electrophotographic photosensitive member was produced by dip-coating a charge transport layer having a dry film thickness of 20 μm on each of the charge generation layers of Examples 1 to 4 and Comparative Examples 1 and 2. These electrophotographic photosensitive members were mounted on a commercially available electrophotographic printer, a halftone image was formed, and image evaluation was performed. As a result, in the image evaluation using the electrophotographic photosensitive member produced from Examples 1 to 4, a good halftone image without image unevenness was obtained using any photosensitive member. In the image evaluation using the obtained electrophotographic photosensitive member, image unevenness occurred in the halftone image.
[0048]
【The invention's effect】
As is clear from the above examples, by using the electrophotographic photoreceptor coating apparatus of the present invention having an independent dry hood, the film thickness of the photosensitive layer or intermediate layer formed on each cylindrical substrate is all The cylindrical substrate can be manufactured with high uniformity, and as a result, a good cylindrical electrophotographic photosensitive member can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an example of a multiple simultaneous dip coating apparatus of the present invention.
FIG. 2 is a view of a coating apparatus using a large dry hood.
FIG. 3 is a diagram of a method for arranging four simultaneous coating apparatuses.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coating liquid 2 Coating liquid tank 3 Supply piping 4 Pump 5 Filter 6 Coating tank 7 Coating liquid receiving tank 8 Recycle pipe 9 Cylindrical base | substrate 10 Coating tank liquid level (overflow surface)
11 Solvent vapor reservoir 12 Discharge port 14 Drying hood 15 Mesh

Claims

In an electrophotographic photosensitive member coating apparatus in which a plurality of cylindrical substrates are simultaneously immersed in a coating solution in a single coating tank and pulled to form a coating film on the cylindrical substrate, a solvent vapor reservoir is formed on the coating tank. An electrophotography comprising a chamber and a drying hood corresponding to each cylindrical substrate on the chamber, and an exhaust port having a gap width of 0.1 to 10 mm between the solvent vapor storage chamber and the drying hood. Photoconductor coating device.

2. The electron according to claim 1, wherein the dry hood is configured such that a gap width between the hood and the cylindrical substrate when passing through the cylindrical substrate is 1/10 to 1 in terms of a diameter ratio of the cylindrical substrate. Photoreceptor coating device.

The electrophotographic photosensitive member coating apparatus according to claim 1, wherein the dry hood has a plurality of ventilation holes.

The electrophotographic photosensitive member coating apparatus according to claim 3, wherein an opening diameter of one of the air holes is 0.1 to 10 mmφ.

5. The electrophotographic photosensitive member coating apparatus according to claim 3, wherein an opening area ratio of the entire ventilation hole (relative to an area of the entire dry hood) is 5 to 50%.

A coating film is formed on a cylindrical substrate by simultaneously immersing a plurality of cylindrical substrates in a coating solution using the electrophotographic photoreceptor coating apparatus according to any one of claims 1 to 5. A method for applying an electrophotographic photosensitive member.

The electrophotographic photosensitive member coating method according to claim 6, wherein the electrophotographic photosensitive member has a coating thickness of 5 to 300 μm.

8. The method for coating an electrophotographic photosensitive member according to claim 6, wherein the coating solution is a coating solution for forming a charge generation layer.