JP2004109754A - Device and method for forming image and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device where occurrence of filming caused by a photoreceptor surface state, a twist of a blade edge with a high friction coefficient on a surface of a photoreceptor, a size of photoreceptor surface roughness, a toner particle form, a corona product and residual fine particles (paper powder, toner component and the like) is prevented and image quality of satisfactory S/N and resolution can be maintained and to provide an image forming method and a process cartridge. <P>SOLUTION: In the image forming device cleaning the residual fine particles on the photoreceptor 1, lubricant 201 is given to the surface of an electrophotographic photoreceptor 1 whose ten point average roughness Rz<SB>JIS</SB>is 0.3 to 1.0 μm and maximum height Rz is 0.4 to 1.5 μm. A cleaning brush 7-1 and a cleaning blade 7-2 are simultaneously operated. Thus, an average abrasion amount (t) of a photosensitive layer per 10,000 sheets is kept to 0.1 μm≤t≤0.5 μm (in electrophotographic photoreceptor conversion of ϕ30mm) so as to form an image. <P>COPYRIGHT: (C)2004,JPO

Description

ポリビニルブチラール　　　　　　　　　　　　　　　　　　　　２部
２−ブタノン　　　　　　　　　　　　　　　　　　　　　　２００部
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　４００部
【０１５１】
〔フィラー非分散電荷輸送層用塗工液〕
ビスフェノールＺ型ポリカーボネート　　　　　　　　　　　　１０部
（帝人化成社製：Ｚポリカ　Ｍｖ５万）
下記［化２］に示される構造の低分子電荷輸送物質　　　　　　　８部
【０１５２】
【化２】

テトラヒドラフラン　　　　　　　　　　　　　　　　　　　２００部
【０１５３】
２）フィラー分散電荷輸送層の作製
フィラー非分散電荷輸送層を塗布した有機感光体を加熱乾燥した後冷却し、引き続き、スプレー塗工法でフィラー分散電荷輸送層を２〜１０μｍの間で塗工した。
フィラー非分散電荷輸送層上に、下記記載のバインダー樹脂（ビスフェノールＺ型ポリカーボネート樹脂）と低分子電荷輸送物質（ドナー）、一次粒径０．３、０．５、０．７および１μｍの４種類の下記無機フィラーを用意し、夫々の無機フィラーと分散助剤及び溶剤を硝子ポットに入れ、ボールミルで２４時間分散させて塗工液を作り、スプレー法を用いて１〜５回往復させ、フィラー分散電荷輸送層を塗工した。触指乾燥の後、１５０℃２０分間加熱乾燥させて、フィラー分散電荷輸送層を有する評価用電子写真感光体を作製した。
【０１５４】
［フィラー分散電荷輸送層塗工液］
ビスフェノールＺ型ポリカーボネート　　　　　　　　　　　　　１０部
（帝人化成社製：Ｚポリカ　Ｍｖ５万）
下記構造式［化３］で示される電荷輸送物質　　　　　　　　　　　７部
【０１５５】
【化３】

アルミナフィラー　　　　　　　　　　　　　　　５．３部〜１１．４部
（住友化学工業製ＡＡ−０２〜１０、平均一次粒径：０．２〜１．０μｍ）
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　４００部
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　　２００部
分散助剤（ＢＹＫ−Ｐ１０４　ビックケミージャパン製）　　０．０８部
作製した感光体の一覧を表１に示す。
【０１５６】
【表１】

（注）表中、Ｒｚ_ＪＩＳは１０点平均粗さ、Ｒｚは最大高さを、フィラー粒径は平均粒径を夫々表わす。
【０１５７】
＜帯電部材＞
非接触帯電用の帯電部材
φ７ｍｍの真鍮製ロット棒に、電気抵抗が４×１０^６Ω・ｃｍ（１００ＶＤＣ印加時）となるシリカ、フッ素樹脂を分散したエピクロルヒドリンゴムを塗布したあと、研磨して、１０点平均粗さが７２μｍ、ＪＩＳ−Ａ硬度が８７度の外径φ１０ｍｍ×３２９ｍｍ（有効帯電幅：３０８ｍｍ）となる帯電部材を用意した。
この帯電部材の両端部から１ｍｍ内側に、厚さ４９μｍ、幅７．５ｍｍ、長さ３１ｍｍの菱形にカットしたＰＥＴ（ポリエチレンテレフタレート）を張り付けスペーサーとする非接触帯電部材を作製した。なお、感光体と帯電部材間の距離は平均で６２μｍであった。
【０１５８】
＜感光体表層への潤滑剤の付与方法＞
重量平均粒径が約４．８μｍ、平均円形度が０．９２４の粉砕トナー（流動剤としてＳｉＯ_２＝０．７％、ＴｉＯ_２＝０．８％添加）に、平均粒径が０．３μｍのステアリン酸亜鉛（ＳＺ２０００）を０．０３％、若しくはテトラフルオロエチレン（ＰＴＦＥ、ルブロンＬ−２　ダイキン工業）を０．１７重量％添加することによって、感光体表層に潤滑剤を付与する方法で実施した。
なお、現像剤のキャリアには、重量平均粒径５８μｍの磁性キャリア（ＦＰＣ−３００ＬＣ）を使用した。
【０１５９】
＜クリーニング装置＞
１．クリーニングブラシ
繊維径１５デニール、４８フィラメント／４５０ループ、ループ長さ３ｍｍのナイロン繊維製のベルトロン（久保田織物製）、アクリル系繊維ＳＡ−７（（株）槌屋製）の夫々を幅１０ｍｍのひも状にカットし、φ５ｍｍの真鍮製ロッド棒に巻き付け接着剤を用いて貼り付け固定し、２種類のクリーニングブラシを各５本作製した。
つぎに、この内各２本に樹脂被覆を行ない、繊維の強度を図った。条件はトーヨーポリマー社の水系ウレタン接着剤メルシ５８５を主剤、同じくトーヨーポリマー社のエポキシＡＤ−Ｃ−６５を硬化剤として、粘度が４１ｍＰａ・Ｓになる様にイオン交換水を希釈溶媒として使用し、架橋剤を主剤５部に対し、架橋剤の添加量を５重量％になる様に１．２５の水を添加し得られた液体に、前記クリーニングブラシの表面より２ｍｍ浸漬させて、取り出し後１６０℃１０分の乾燥を行なった。
【０１６０】
２．クリーニングブレード
ＪＩＳ−Ａ硬度が７７度で、厚み２ｍｍ、幅１１．６ｍｍ、長さ３２６ｍｍの短冊（シート）状のポリウレタンゴムを板厚１ｍｍ、長さが３６３ｍｍのＬ字型鉄製部材にホットメルト接着剤で取り付けられたものを使用した。自由長は８ｍｍである。
【０１６１】
＜評価方法＞
評価用装置として４本の感光体とＹ、Ｍ、Ｃ、Ｂｋの４系統の現像器、１転写ベルトを装着する、４連タンデム方式のカラーレーザープリンター（イプシオカラー８０００（２８枚／分）リコー製）を用意した。但し、実験にはＹ、Ｍ及びＢｋの位置にダミードラムを装着し、Ｃの位置にシアントナーを入れて評価した。感光体に潤滑剤を付与する手段としては、ステアリン酸亜鉛をトナーに対し０．０３重量％含有させることによって行なった。
評価枚数はＡ４サイズ各５万枚とし、初期の感光層膜厚と５万枚後の膜厚を渦電流式膜厚計（フィッシャー社製　タイプｍｍｓ）を使って、２０ｍｍ間隔で１３ポイント測定し、感光層の摩耗量（１３ポイントの平均値）を評価した。
【０１６２】
＜実施例１〜４＞
表１に記載の感光体サンプルより、フィラー分散電荷輸送層中に添加したフィラー粒径の異なる、Ｎｏ．４、８、９、１２のサンプル４本を選定し評価に使用した。各感光体の搭載位置はシアン位置のみとして、他の３カ所には、同等の特性を有するダミー感光体を搭載した。帯電には非接触帯電ローラを搭載し、帯電部材に直流電圧−７７０ＶとＰｅａｋ　ｔｏ　Ｐｅａｋ電圧（Ｖｐ−ｐ）１８５０Ｖ／１３５０Ｈｚの交流電圧を重畳して印加し、帯電々位を−７００〜−７１０Ｖになる様に設定した。この時の感光体の画像部電位は４本の感光体で−５０〜−８０Ｖであった。現像バイアスは−６００Ｖに設定した。
クリーニング装置はクリーニングブレードとクリーニングブラシから構成され、クリーニングブラシの回転方向は感光体の回転とは逆回転（順方向）とし、ブラシにはフリッカーバーは非設置とした。
トナーには融点が１６０℃のリコー製シアントナーを使用し、潤滑剤（ステアリン酸亜鉛）を０．０３重量％添加し、キャリア（ＦＣＰ−３００ＬＣ）に対して５重量％になる様に調整した。
評価枚数はＡ４サイズで５万枚とした。
【０１６３】
評価項目は、Ｉ）摩擦係数、ＩＩ）１ドットハーフトーン画像の均一性（プリンター内部パターン使用）、ＩＩＩ）感光体外観特性（フィルミングの有無確認）、ＩＶ）感光層摩耗量（フィッシャー社膜厚計ｍｍｓを使用）、Ｖ）解像度（コダック社製図票Ａ（ＪＩＳ　Ｚ　６００８）を使用）及び表面粗度（１０点平均粗さＲｚ_ＪＩＳ、最大高さＲｚ）とし、潤滑剤を常時感光体に付与時の摩耗力強化を図ったナイロン製クリーニングブラシ（ベルトロンブラシ）の効果を確認した。結果を表２に示す。
【０１６４】
５万枚後も感光体表層は光沢を帯びており、摩擦係数はいずれも０．３台を示し良好であった。その結果、感光層の摩耗量は０．３〜０．４μｍと少なく良好であり、トナーや紙粉に起因するフィルミングは画像形成領域には皆無で、画像流れ現象もなかった。
評価後、クリーニングブラシを外し、トナーを充分に取り除いた後、光学顕微鏡で樹脂の剥がれ状態を確認したが、剥がれはあるものの、まだ、充分に被覆されており、クリーニング性は充分にあることが観測された。
【０１６５】
【表２】

表中、Ｒｚ_ＪＩＳ、Ｒｚは表面粗度を表わし、Ｒｚ_ＪＩＳは１０点平均粗さ、Ｒｚは最大粗さを表わす。感光層摩耗量は５万枚評価後の１万枚当たりの摩耗量を表わす。１ドットハーフトーン均一性はＡ３サイズ画像での評価結果である。解像度は、「縦解像度／横解像度」を表わし、５．６本／ｍｍ以上あれば実用上支障はない。
判定の○は実用上問題なし、△は５万枚の評価で実用的には問題は軽微であるが今後問題となる、×は５万枚の評価で実用性が低いことを表わす。
以下の表についても同様である。
【０１６６】
＜比較例１〜４＞
評価用の感光体として、表１に記載のＮｏ．３、５、１０及びＮｏ４と同仕様の感光体４Ｂを用意し、夫々をシアン用の感光体ユニットに装着した。クリーニングブラシは摩耗力強化を行わない元の状態のループ状クリーニングブラシに交換し、通常のループブラシを装着し、潤滑剤を感光体に付与したときのフィルミング生成の有無、及びフィルミングの評価を実施した。評価方法は実施例１〜４と同様である。結果を表３に示す。
摩耗力強化を行なわなかったクリーニングブラシでは、いずれも帯状のフィルミングが生じたが、特に表面粗度が大きかったＮｏ．７（Ｒｚ_ＪＩＳ＝１．２μｍ、Ｒｚ＝１．７５μｍ）及びＮｏ．１０（Ｒｚ_ＪＩＳ＝０．９３μｍ、Ｒｚ＝１．６３μｍ）の２本の感光体では、５万枚後のフィルミングが全体に広がり、帯電ローラも青白っぽい汚れが全長さに亘って認められた。その他の２本の感光体もフィルミングは認められたが、Ｎｏ．７及びＮｏ．１０に比べて程度は良かった。
【０１６７】
【表３】

【０１６８】
＜比較例５〜８＞
評価用の感光体として、表１に記載のＮｏ．１、２、Ｎｏ．８と同仕様で作製したＮｏ．８Ｂ及びＮｏ．１５の感光体を用意し、夫々をシアン用の感光体ユニットに装着した。クリーニングブラシは摩耗力強化を行なった実施例１〜４に使用したものと同じ仕様のループ状クリーニングブラシを使用し、現像剤のシアントナーについてはステアリン酸亜鉛が添加されていないトナーを使用した。評価は実施例１〜４と同様とし、ステアリン酸亜鉛の付与がない状態での、摩耗力強化を図ったクリーニングブラシを使用したときの効果確認を実施した。結果を表４に示す。
摩耗力強化を図ったクリーニングブラシを使用せず、潤滑剤を付与しない状態では、摩擦係数が大きくなり、その結果、感光層が大きく摩耗した。摩擦係数が大きくなった結果、クリーニングブレードに歪み（捻れ）が生じ、トナーの抜けが多くなったため、フィラーを添加した感光体ではいずれも、フィルミング現象が発生したが、フィラーを分散しない感光体では、トナー抜けは生じたが、摩耗が多いためにフィルミングが発生することはなかった。
【０１６９】
【表４】

【０１７０】
＜実施例５〜８＞
フィラー非分散電荷輸送層（電荷輸送層）の膜厚を１０〜４０μｍで変化させ、摩耗力強化させたループブラシにステアリン酸亜鉛を添加したシアントナーとの組み合わせ時のフィルミングの生成、フィルミングに因る影響を評価した。評価方法は実施例１〜４に記載の内容と同様とした。結果を表５に示す。
感光層の厚みを変えても、摩耗力をアップさせたループブラシの効果は維持され、４サンプルともフィルミングの生成は皆無で、摺擦傷はあるが光沢は程良く保っており、良好な外観状態で、解像度低下も生じなかった。膜厚が厚い感光体（Ｎｏ．１４感光体）では解像度の低下が見られ、画像流れによらない文字太りを生じ、解像度は縦５．０本／ｍｍ、横５．６本／ｍｍであった。
【０１７１】
【表５】

【０１７２】
＜実施例９〜１１＞
トナーに添加する潤滑剤をステアリン酸亜鉛からポリテトラフルオロエチレン（ＰＴＦＥ）に変え、トナー中への添加量を０．１５重量％とした。評価用の感光体には表１に記載のＮｏ．３と４と同仕様で作製した感光体Ｎｏ．３Ｂ、Ｎｏ．４ＣとＮｏ．６の感光体を使用し、その他の条件は実施例１〜４と同じ内容で評価を行なった。結果を表６に示す。
潤滑剤をステアリン酸亜鉛に変えても、フィルミングは良好に抑制し、好結果であった。画像品質はステアリン酸亜鉛より、シャープ性が増し、切れの良いライン画像を呈した。摩擦係数は０．２台を示し、感光層の摩耗はステアリン酸亜鉛使用時より少ない結果となった。
【０１７３】
【表６】

【０１７４】
＜実施例１２〜１６＞
ループブラシを摩耗強化したアクリル系繊維のＳＡ−７に交換し、また、トナーには０．１５重量％のポリテトラフルオロエチレン（ＰＴＦＥ）を添加したシアントナーをキャリアに５重量％添加して使用した。評価用の感光体には表１に記載のＮｏ．４、５、６、１２及び１に記載の感光体と同仕様で作製した感光体Ｎｏ．４Ｄ、５Ｂ、６Ｂ、１２Ｂ及び１Ｂを使用し、その他の条件は実施例１〜４に同じ内容で評価を行なった。結果を表７に示す。
結果は実施例１〜４と同じで、５サンプルともフィルミングは皆無であり、解像度低下はなかった。また、摩擦係数も低いレベルで推移し、摩耗も少なかった。但しフィラーを添加しなかったＮｏ．１Ｂの感光体は、摩耗が１万枚当たり１．１μｍと多くなり、フィルミングの発生はなかったが、耐久性の面では不充分となった。その他の特性は良好であった。
【０１７５】
【表７】

【０１７６】
＜実施例１７〜１９＞
・評価用感光体の作製方法
本発明で使用する感光体を下記の要領で作製した。
φ１００ｍｍ、長さ３６０ｍｍ、肉厚１ｍｍのアルミニウムドラムに下記組成の下引き層（ＵＬ）用塗工液を用いて浸漬塗工を行ない、１３０℃３０分加熱乾燥を行ない、約４μｍの下引き層を形成した。
次に、電荷発生層（ＣＧＬ）用塗工液を用いて浸漬塗工し、１５０℃２５分の加熱乾燥により０．２μｍの電荷発生層を形成し、更に、電荷輸送層（ＣＴＬ）用塗工液を用い浸漬塗工を行ない、１４０℃３０分の加熱乾燥により約２５μｍ電荷輸送層を塗工し有機感光体を作製した。この感光体上に、さらにバインダー樹脂とドナー、平均粒径が０．３又は０．５又は０．７μｍ又は１．０μｍの無機微粒子（金属酸化物）、添加剤及び溶媒を硝子ポットに入れ、ボールミルで２４時間分散させ、平均粒径（堀場製作所製ＣＡＰＡ５００で測定）約０．５μｍの塗工液を作り、スプレー法を用いて４回塗布（約１．２〜１．５μｍ／回）し、加熱乾燥させて約５μｍの被覆層を形成し電子写真感光体を完成した。
以下に記載の部はいずれも重量部を表わす。
【０１７７】
〔下引き層用塗工液〕
アルキッド樹脂　　　　　　　　　　　　　　　　　　　　　　　６部
（ベッコゾール　１３０７−６０−ＥＬ、大日本インキ化学工業社製）
メラミン樹脂　　　　　　　　　　　　　　　　　　　　　　　　４部
（スーパーベッカミン　Ｇ−８２１−６０、大日本インキ化学工業社製）
酸化チタン（ＣＲ−ＥＬ、石原産業社製）　　　　　　　　　　４０部
メチルエチルケトン　　　　　　　　　　　　　　　　　　　２００部
〔電荷発生層用塗工液〕
オキソチタニウムフタロシアニン顔料（リコー製）　　　　　　　２部
ポリビニルブチラール（ＵＣＣ：ＸＹＨＬ）　　　　　　　　０．２部
テトラヒドロフラン　　　　　　　　　　　　　　　　　　　　５０部
〔電荷輸送層（無機フィラー非分散電荷輸送層）用塗工液〕
ビスフェーノールＡ型ポリカーボネート　　　　　　　　　　　１０部
（帝人化成社製：Ｚポリカ）
下記［化４］に示す構造の低分子電荷輸送物質　　　　　　　　１２部
【０１７８】
【化４】

塩化メチレン　　　　　　　　　　　　　　　　　　　　　　１００部
メチルフェニルシリコーンオイル（５０ｃｓ）　　　　　　　　　１部
〔フィラー分散電荷輸送層用塗工液〕
フィラー分散電荷輸送層用塗工液はバインダー樹脂と無機微粒子が重量比で２０％、電荷輸送物質とバインダー樹脂の比が７／１０になるように混合し、シクロヘキサノンを溶媒としてスプレー法で１〜３回のスプレーを行ない、４種の被覆層を形成した。
バインダー樹脂：ポリカーボネート樹脂　　　　　　　　　　　１０部
（Ｚポリカ、帝人化成社製、Ｍｖ５万）
フィラー：アルミナ粉末　　　　　　　　　　　　　　　　　５．７部
（ＡＡ−０３、ＡＡ−０５、ＡＡ−０７、ＡＡ−１０、住友化学工業社製）
但しＡＡ−０７については５．７部以外に１１．４部添加した感光体（サンプルＮｏ．２０）に付いても作製した。
下記［化５］に示す低分子電荷輸送物質　　　　　　　　　　　　７部
【０１７９】
【化５】

分散助剤：（ＢＹＫ−Ｐ１０４、ビックケミージャパン製）　０．１部
テトラヒドラフラン　　　　　　　　　　　　　　　　　　　７００部
シクロヘキサノン　　　　　　　　　　　　　　　　　　　　２００部
作製した感光体の測定結果を表８に示す。
【０１８０】
【表８】

評価装置には、帯電装置を非接触帯電ローラ用に改造したイマジオＮｅｏ６００（（６０枚／分）　リコー製）を用意した。
感光体の帯電に使用する非接触帯電部材には、前記実施例に記載と同仕様のエピクロルヒドリンゴムを使用して、φ１８ｍｍの外径寸法に仕上げた。この様にして作製した帯電ローラの両端部に幅１０ｍｍの菱形状の厚みが４９μｍのＰＥＴ（ポリエチレンテレフタレートフィルム）を両面テープで貼り付けて、スペーサーとした。因みに感光体と帯電部材間のＧａｐは約６１μｍであった。
一方、短冊状にカットした幅１２ｍｍのナイロン製ベルトロンを芯金に螺旋状に巻き付け、接着剤で固定し、外径寸法が１８ｍｍ、ループ長さ約３．５ｍｍとなるクリーニングブラシを作製した。
これらの部材を評価装置に装着し、帯電部材に−７６０Ｖの直流電圧、及び１８００Ｖ／１５００Ｈｚの交流電圧を重畳させて印加し、直流電圧を微調整することによって帯電々位を−７００〜−７１０Ｖに設定し、１０万枚の通紙評価を実施した。因みに画像部電位は−１５０Ｖ〜−１８０Ｖであった。
現像剤にはイマジオＮｅｏ６００用のブラックトナーにステアリン酸亜鉛を０．０２％添加したトナーを使用した。結果を表９に示す。
フィルミングはいずれの感光体サンプルにおいても生成されておらず、光沢も比較的良好に保っていた。また、解像度に関しても良好であり、シャープ性については初期に比べ僅かに低下したものの、表９に示すような結果が得られ、いずれのサンプルも問題なかった。また、ループブラシの樹脂被覆層は、局所的に剥がれの部分があったが、クリーニング性を低下させる程の状況ではなかった。
【０１８１】
【表９】

表中、感光層摩耗量はφ３０ｍｍの感光体に換算した１万枚当たりの摩耗を示す。
【０１８２】
＜比較例９〜１０＞
評価用の感光体として表８に記載のＮｏ．１９及び２０の感光体を使用し、実施例１７〜１９と同じ方法で評価した。結果を表１０に示す。
表面粗度が大きくなる（Ｒｚ_ＪＩＳが１．０以上、Ｒｚが１．５以上）ことで、トナーのブレード抜けが多くなったため、クリーニングブラシでの摩耗力が不足し、局所的にフィルミングの発生が確認された。
このため、画像品質（ハーフトーン画像にムラ、解像度が局部的に低下、文字画像の太りによる潰れ）が低下した。
【０１８３】
【表１０】

表中、感光層摩耗量はφ３０ｍｍの感光体に換算した１万枚当たりの摩耗を示す。
【０１８４】
【発明の効果】
以上、詳細かつ具体的な説明より明らかなように、本発明の請求項１に記載の構成によって、１０点平均粗さＲｚ_ＪＩＳが０．３〜１．０μｍ、最大高さＲｚが０．４〜１．５μｍである感光体に、潤滑剤を付与しながらクリーニングブラシとクリーニングブレードを同時に作動させ、φ３０ｍｍの感光体で１万枚当たりの感光層の摩耗量を表層より０．１〜０．５μｍに保持することによって、残留粉体（トナー、紙粉、埃などによって構成される）のクリーニング不良、コロナ生成物の等の作用によって生じるフィルミング生成を防止することができ、且つ感光体表層の摩擦係数が低いレベルに維持されるため、解像度低下、画像流れ、などの画像品質低下がなくなり、また感光層の摩耗も低く抑えられるので、シャープ性の良好な、ムラのない画像を長期にわたって維持することが可能である。また、請求項２の構成によって、クリーニングブラシとしてポリエステル繊維、ナイロン繊維、アクリル繊維の何れかの１種類の繊維を用いて、ループブラシを構成し、感光体に面接触させ、摺擦させる様に配置させることによって、感光体上の残留粉体を長期にわたって、安定してクリーニングできると共に、繊維に強化を図ることによって、感光層上のフィルミングがムラなく均一に除去できる。また、請求項３の構成によって、クリーニングブラシは、短冊状にカットしたループブラシを芯金上に螺旋状に隙間なく巻き固定する手段を講じることによって、簡単に且つ迅速にクリーニングブラシを作製することができる。この様にして作製されたブラシはずれがなく、長期にわたって安定した残留粉体のクリーニングを保証する。また、請求項４の構成によって、少なくとも、ループ状クリーニングブラシのクリーニングに供される領域の繊維を、樹脂被覆し機械的強化を図ることによって、感光層に固着したフィルミングをクリーニングブラシの摺擦力によって、残留粉体のクリーニングは勿論のこと、生成された微少なフィルミングを小さい内に削り取り、広がりを阻止するため、高品位の画像を長期にわたって維持することが可能である。また、請求項５の構成によって、ループ状ブラシの機械的強化図る樹脂層の付与を浸漬法で行なうことによって、簡単に、確実に、充分なる樹脂コーティングを行なうことができるため、劣化が少なく、長期にわたってクリーニング性能を維持することができる。また、請求項６の構成によって、ループブラシにフリッカーバーを使用しないことによって、トナーがブラシの奥に溜まって、クリーニング機能が低下することを防止できること。また、フリッカーバーによる機械的ダメージがないため、長期にわたって良好なクリーニング性が維持できる。また、請求項７の構成によって、ループブラシの回転を感光体の回転とは逆方向に回転させることによって、感光層の削れ過ぎ及び、偏摩耗が少なくなり、感光体の長寿命が図られる。また、異常画像の発生も回避できる。また、請求項８の構成によって、感光体の電荷輸送層に耐摩耗性を図るために、０．３〜０．７μｍ粒径のフィラーを、２０重量％以上、３５重量％以下添加することによって、強化を図ったループブラシを使用しても、必要以上に感光層が摩耗することがなく、解像度、シャープ性良好な作像が行なえ、感光体の長寿命化も図ることができる。また、請求項９の構成によって、感光体表層に付与する潤滑剤として、ステアリン酸亜鉛、若しくはポリテトラフルオロエチレンの何れかを使用することによって、摩擦係数が低減化でき、その摩擦係数を０．２〜０．４５の間に維持することによって、シャープ性良好で、感光層の摩耗が必要以上に摩耗することを防止することができる。また、感光体表面の谷の部分に、適度に潤滑剤が入り込むため、コロナ生成物の付着が抑えられ、画像流れの抑止策になる。また、請求項１０の構成によって、感光体を帯電する手段として、感光体とニップを形成する接触帯電ローラを使用することによって、低い電圧で、画像均一性の良い帯電が行なわれ、その結果、均一性の高いＳ／Ｎの高い画像品質が保証できる。また、請求項１１の構成によって、感光体を帯電する手段として、感光体と帯電部材間に微少Ｇａｐを３０μｍ以上、１００μｍ以下に保持させることによって、帯電ローラの汚染が少なくなり、また、感光体にキャリアなどの微少金属が刺さることによるピンホールが少なくなるため、放電破壊に対する余裕度が上がる。また、安定した帯電を行なうことができる。また、請求項１２の構成によって、請求項１〜請求項１１に記載の何れかの電子写真感光体、帯電装置、クリーニングブラシ及びクリーニングブレードから構成されるクリーニング装置、潤滑剤塗布手段を使用する間接電子写真法を用いた画像形成方法を使用することによって、フィルミングのないシャープ性良好な作像が行なわれ、しかも感光層の過剰な摩耗がないため、長期にわたって安定した画像が提供可能である。また、請求項１３の構成によって、請求項１〜請求項１１に記載の電子写真感光体、帯電装置、クリーニングブラシ及びクリーニングブレードから構成されるクリーニング装置、潤滑剤塗布手段から選ばれる少なくとも１つのユニットを支持し、画像形成装置に着脱自在のプロセスカートリッジを構成することによって、異常画像が生じた場合や、ユニットの寿命に達した場合には、画像形成装置を短時間に取り出し、装着が可能であるため、確実に元の状態に復させることが可能となる。
【図面の簡単な説明】
【図１】フリッカーバーを付設しないクリーニングブラシとクリーニングブレードから構成されるクリーニング装置を備えた本発明の複写プロセスを説明する画像形成装置の概略図である。
【図２】フリッカーバーを付設しないクリーニングブラシとクリーニングブレードから構成されるクリーニング装置及び、感光層表面に潤滑剤を付与する装置を備えた本発明の複写プロセスを説明する画像形成装置の別の概略図である。
【図３】感光体を４本、マゼンタ、シアン、イエローおよびブラックの４色の現像装置を使用した４連タンデム方式のカラーレーザービームプリンターの概略図である。
【図４】本発明に使用する機能分離型の感光体構成を説明する概略図である。
【図５】図４の電荷輸送層がフィラー非分散電荷輸送層と、フィラー分散電荷輸送層の２層からなる構成される機能分離型の感光体を説明する概略図である。
【図６】感光体表層の表面粗度（１０点平均粗さＲｚ_ＪＩＳ、最大高さＲｚ）のフィラー粒径依存性を説明するグラフである。
【図７】φ６０ｍｍ感光体の感光体表層の表面粗度（１０点平均粗さＲｚ_ＪＩＳ、最大高さＲｚ）の電荷輸送層へのフィラー添加量依存性を説明するグラフである。
【図８】φ３０ｍｍ感光体の感光体表層の表面粗度（１０点平均粗さＲｚ_ＪＩＳ、最大高さＲｚ）の電荷輸送層へのフィラー添加量依存性を説明するグラフである。
【図９】本発明で使用するクリーニングブラシの繊維がループ状に織られて作製されている状態を説明する概略図である。
【図１０】本発明に使用するクリーニングブラシの外観図である。
【図１１】短冊状のクリーニングブレードとクリーニングブラシとの組み合わせを説明するクリーニング装置の配置を示す概略図である。
【図１２】ナイフエッジ状のクリーニングブレードとクリーニングブラシとの組み合わせを説明するクリーニング装置の配置を示す概略図である。
【図１３】短冊状のクリーニングブレードの当接状態を示す概略図である。
【図１４】ナイフエッジ状のクリーニングブレードの当接状態を示す概略図である。
【図１５】本発明の使用する非接触帯電装置用の帯電ローラの概略図である。
【符号の説明】
１：電子写真用感光体（感光体）
２：帯電装置
３：画像露光装置
４：現像装置
５：転写装置
６：分離装置
７：クリーニング装置
７−１：クリーニングブラシ
７−２：クリーニングブレード
８：定着装置
９：コピー用紙
２０：帯電器
２００：潤滑剤付与装置
２０１：潤滑剤
２０２：潤滑剤付与ブラシ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is capable of avoiding a filming phenomenon caused by a corona product, paper dust, toner, etc. sticking to a photoreceptor, maintaining a good image quality without lowering the resolution and causing image deletion. The present invention relates to an image forming apparatus, an image forming method, and a process cartridge that can be used.
[0002]
[Prior art]
Desktop or floor type image forming apparatuses using indirect electrophotography, such as facsimile machines, laser printers, and electrophotographic copiers, mainly include an electrophotographic photosensitive member (hereinafter simply referred to as a photosensitive member), a charging device, and an image forming device. An exposing device, a developing device, a transfer device, a separating device, a cleaning device, a charge removing device, and a fixing device are arranged to perform image formation.
Conventionally, photoreceptors include zinc oxide (ZnO), cadmium sulfide (CdS), cadmium selenide (CdSe), and amorphous selenium (a-Se, a-Se-Te, a-As). ₂ Se ₃ Inorganic photosensitive materials such as amorphous silicon (a-Si: H) have been used, but in recent years, there are many advantages such as easy fabrication, high sensitivity design, low cost, and no pollution. Organic photoconductors are mainly used.
[0003]
The structure of the organic photoreceptor can be classified into a function-separated type in which the photosensitive layer includes a charge transport layer and a charge generation layer, and a layered structure in which a charge generation material and a charge transport material are mixed. Most of the layer structure of the photoreceptor circulating in the market is a function-separated type photoreceptor except a part, and the basic layer structure of the photoreceptor is an undercoat layer, a charge layer on a conductive support such as aluminum. It has a layer structure in the order of a generation layer and a charge transport layer.
[0004]
Means for applying the charge required for image formation to the surface of the photoreceptor include a scorotron type corona charging method having a grid, a brush, a roller, and a contact charging method in which a charging member such as a blade is disposed in contact with the photoreceptor (for example, And a non-contact charging method (also referred to as a proximity charging method) in which the photosensitive member is separated from the photosensitive member by about 30 to 100 μm.
A DC voltage or a DC voltage on which an AC voltage is superimposed is applied to the charging device, and the photoconductor is charged to about 400 to 800V. In the case of a function-separated type organic photoreceptor, the charge is usually negative (-).
[0005]
[Patent Document 1]
JP 2001-318475 A (page 3, column 4, lines 8 to 24)
[0006]
After the charging process is completed, an optical writing of a document image (in the case of a digital method, an LD (Laser Diode) or an LED (Laser Emitting Diode) is used as a light source for irradiating the image on the photoconductor, and the image of the dot pattern is formed. Is irradiated) to form an electrostatic latent image in the photosensitive layer.
Next, the electrostatic latent image is visualized by a developing device of a reversal developing method (an exposed portion is represented as an image, and a charged position is represented as a background portion), transferred to a copy sheet by a transfer device, and fixed by a fixing device. Sent to a hard copy. On the other hand, the residual toner on the photoconductor after the transfer is cleaned on the photoconductor surface by the cleaning device, and a series of image forming processes is completed.
[0007]
By the way, a blade-type cleaning device using a rubber material is generally used as a cleaning device for cleaning toner.
The blade is made of polyurethane rubber which is excellent in cleaning properties and durability. Rubber materials such as neoprene rubber, chloroprene rubber, silicone rubber, and fluororubber are easily adhered to highly smooth objects as used for packing and the like. Polyurethane rubber is no exception. Therefore, when used as a cleaning blade for the photoreceptor, the edge portion cut into a rectangle is pressed and fixed so as to make line contact with the surface of the photoreceptor.
However, even if it is set so as to make line contact, the blade is actually in contact with the photoconductor with a nip, so-called surface contact due to the pressure and elasticity of the blade material. Completely adhered. Therefore, the cleaning performance is further enhanced, but the contact area with the photoconductor is increased, so that the frictional resistance is increased, and it is almost impossible to rotate the photoconductor.
[0008]
In order to rotate the photoconductor, it is necessary to apply a powder such as toner or polyvinylidene fluoride to reduce the contact resistance before the photoconductor is mounted on the tip of the blade.
However, the fine powder is still insufficient at the edge portion in contact with the photoconductor, so that the tip (edge) of the blade is unevenly dragged or returned in the rotation direction of the photoconductor, that is, a stick phenomenon. A slip phenomenon occurs. Due to this stick-slip phenomenon, a slight gap of several μm to several tens μm may be generated between the photoconductor and the photoconductor.
For this reason, if the toner particle size is smaller than this gap, a phenomenon in which a part of the toner sent one after another to the blade comes off from this gap, so-called toner missing or cleaning failure occurs.
[0009]
The toner used as a developer during image formation has a distorted pulverized toner having an average circularity of about 0.91 to 0.94, and has an average circularity of 0.1, which has recently begun to be used in response to the demand for high-quality images. Polymerized toner having a spherical shape or a true sphere of 96 to 1.0 is mainly used. The average particle size of the toner used is about 4 to 8 μm.
The above-mentioned pulverized toner is classified by a sieve, but cannot be adjusted to a certain particle size, and crushing occurs, so that the particle size distribution is as large as about ± 3 to 4 μm. Therefore, a large amount of toner having a very small particle size of 1 to 2 μm is contained in the developer. For this reason, in the toner having an average particle diameter of 4 μm, the toner having a small particle diameter of about 1 to 2 μm comes off from a slight gap caused by irregularities on the surface of the photoconductor and twisting of the blade, and the like. It contaminates the charging member and causes deterioration of image quality. Therefore, in order to avoid this, a slightly larger toner of 5 to 8 μm may be used as the pulverized toner.
On the other hand, the particle size distribution of the polymerized toner is as small as about ± 1 μm, and the variation of the particle size is small. Therefore, even if the surface of the photosensitive member has irregularities of about 2 μm, the toner having an average particle diameter of 4 μm hardly comes off. However, since the shape is spherical, the toner is easily sunk under the blade as compared with the pulverized toner, and a toner removal phenomenon different from that of the pulverized toner occurs.
[0010]
Filming is likely to occur when toner is missing or toner is scattered. This is because toner, which is a main factor of filming, is strongly pressed against the photoconductor due to the blade edge, and the resin and additives, which are the components of the toner, are exposed to the photoconductor surface by the blade pressure and frictional heat. It is considered to be caused by fusing. However, since the filming phenomenon involves paper dust, corona products, and the like from the transferred material, it is important to eliminate these factors.
Filming is hardly worn because it is firmly attached to the photosensitive layer. Therefore, once formed, they are difficult to be scraped off with a blade or developer. In particular, in the case of a blade used for a long time, the edge portion is worn, and when the surface of the photoreceptor is rough and the surface roughness is large, the cleaning ability is reduced, so that toner is more likely to be removed. Become. Accordingly, the filming film gradually increases in thickness and at the same time spreads over the entire surface of the photoconductor. When the filming is formed, the coefficient of friction of the surface layer of the photoreceptor also increases, so that the formation of the filming is further increased.
When filming is formed on the photoreceptor, it is difficult to remove the corona product attached to the filming surface. As the corona product on filming absorbs moisture in the atmosphere, the filming surface becomes less resistive and progressively degrades image quality resolution, eventually leading to complete image flow. Further, when filming is formed on the surface of the photoreceptor, the amount of light reaching the charge generation layer is reduced, and the light attenuation characteristics are affected, resulting in an image with noticeable unevenness.
[0011]
As the cleaning device, in addition to the blade cleaning device described above, a cleaning device using both a cleaning blade and a cleaning brush is used. The cleaning brush has a function of forcibly cleaning foreign substances that are difficult to remove even with a blade, but a thin film strongly adhered to the surface layer of the photoreceptor, such as filming, can hardly be removed.
Therefore, once the filming formed on the photoreceptor starts to be formed, it gradually accumulates, so that it becomes more difficult to remove the filming, which has a serious influence on the image quality.
[0012]
In order to prevent filming from occurring, there are methods such as increasing the pressure of the blade to completely block toner removal, and removing traces each time before the filming film spreads. In order to completely cut off the toner for a long period of time by increasing the frictional resistance between the blade and the photoconductor, the frictional resistance between the blade and the photoconductor increases. Therefore, the rotation of the photosensitive member becomes unstable, and the blade easily causes the stick-slip phenomenon, which may have an adverse effect. The means for forcibly shaving the surface using an abrasive or the like may cause abrasion of the photosensitive layer and may shorten the life of the photosensitive member.
[0013]
A disclosure example describing means for avoiding filming or the like caused by toner is described below.
A cleaning device including a cleaning blade and a cleaning brush is used. A conductive carrier (electric resistance is unknown) is used as a developer. A conductive seal (10 in this embodiment) is provided on the upstream side of the blade. ³ Ω · cm), the contact width with the photoreceptor is set to 5 to 15 mm, and an AC voltage of 200 to 1000 Hz and 400 to 1000 V is applied, thereby causing damage due to pressing of the carrier against the photoreceptor and poor cleaning. To improve toner filming and obtain stable copy quality for a long period of time (for example, see Patent Document 2).
[0014]
[Patent Document 2]
JP-A-5-313540 (Claim 1 on page 2, column 1, line 2 to line 10)
[0015]
According to this method, the carrier is neutralized by a seal provided at the entrance of the cleaning device, and the electrostatic force is weakened to prevent the carrier from sneaking into the blade, thereby efficiently cleaning the toner and the carrier. .
Although this method has the effect of removing the charge of the toner and the carrier, the charge is removed via the photoreceptor. Therefore, the charge is not sufficiently removed from the carrier, and there is room for improvement in removing the carrier. In addition, when filming occurs once, there is no means for removing the filming, and the effect is insufficient.
[0016]
Damaging the photoreceptor by attaching and covering silicon rubber microparticles (0.05 to 5.0 μm, 1.8 μm in the embodiment) on at least one surface layer of the photoreceptor and the blade or brush of the cleaning member. In addition, filming is prevented (for example, see Patent Document 3).
[0017]
[Patent Document 3]
JP-A-6-337535 (Claim 3, page 1, column 1, line 12 to line 19, page 3, column 4, line 5 to column 3, line 33, page 4) Column 6, line 1 to line 22)
[0018]
In this method, the silicon rubber fine particles are finally transported to the blade, but since the silicon rubber fine particles are elastic, they are not damaged even when pressed against the gap between the cut surface of the blade and the photoconductor.
Further, by filling the gap, the toner is blocked, and the toner is prevented from leaking to the charging member side, so that the cleaning is performed satisfactorily.
This means is highly effective in terms of toner cleaning properties, but if the frictional resistance between the blade and the photoreceptor is large, a gap cannot be prevented. There is a high possibility that the silicone rubber fine particles will fall out of the gap, and the silicone rubber fine particles that have fallen out will adhere to the charging member or enter the developer, and there is a risk that the charging characteristics of the toner may become unstable.
Further, by adding the silicone rubber, a large amount of the silicone rubber enters the toner, and there is a large possibility that the silicone rubber causes image defects.
[0019]
The cleaning brush is brought into contact with a collection roller (a roller for shaving the lubricant and supplying it to the brush and for collecting the attached lubricant) having a 10-point average roughness Rz of 3 to 20 μm. Lubricating is brought into contact with the collecting roller, and the lubricant is supplied to the photoreceptor via the cleaning brush, thereby preventing filming caused by the toner additive (for example, see Patent Document 4).
[0020]
[Patent Document 4]
JP-A-10-74028 (Summary of first page, left column, first line to last line)
[0021]
This means forms a film of a lubricant (for example, zinc stearate) on the surface of the photoreceptor, thereby reducing the adhesion of the toner to the surface of the photoreceptor and facilitating cleaning of the toner additive. . In general, when zinc stearate is applied through a brush, it is easily applied thickly, so that a corona product is easily taken into a lubricant, and thus there is a problem that image deletion is likely to occur. Therefore, when zinc stearate is used, a supply method is required to form an extremely thin film that can be easily removed.
Further, since zinc stearate is a wax, the collecting roller easily causes clogging, and thus it is difficult to maintain the collecting roller.
The 10-point average roughness Rz described in Patent Document 3 is an old JIS standard and is described as it is. Since the surface roughness of the present invention is described by a symbol according to the new JIS standard, Rz _JIS Has become
Further, it is described that a lubricating substance such as a fluororesin is attached to the surface of the photoreceptor in a direction perpendicular or substantially perpendicular to the rotation axis direction of the photoreceptor (for example, see Patent Document 5). .
[0022]
[Patent Document 5]
JP-A-2000-352832 (Claims 1 to 6 on page 2, column 1, line 2 to line 27)
[0023]
Lubricant and antiwear agent (Al) on the surface of the image holding member (photoreceptor) ₂ O ₃ , SiC, SiO ₂ , B ₄ C is dispersed in a resin to provide an insulating layer, whereby the surface of the photoconductor is adjusted with a lubricant while the low-resistance substance attached to the surface of the photoconductor is shaved with an anti-wear agent (for example, Patent Document 6). reference.).
[0024]
[Patent Document 6]
JP-A-56-99347 (page 5, lower right column, line 5 to page 3, upper left column, line 4)
[0025]
Although the low-resistance substance formed on the photoreceptor by the lubricant can be removed, the above-mentioned material has a function similar to that of a paper file, and thus has a drawback of abrasion. Another problem is that the lubricant removed from the insulating layer is stabbed into the photosensitive layer, and tends to cause abnormal images such as white spots and black spots.
[0026]
Fiber used for cleaning brush (conductive fiber, 50 to 200 bundles / inch) ² , 2000 to 20000 pieces / inch ² By specifying the configuration of (1) and applying an AC voltage equal to or higher than the discharge start, paper dust and fibers of copy paper, which are difficult to remove with a cleaning blade, are efficiently cleaned to make filming difficult. (For example, see Patent Document 7).
[0027]
[Patent Document 7]
JP-A-9-90838 (page 3, column 3, line 40 to column 4, line 10)
[0028]
In this method, the cleaning property is improved as compared with the conventional method by reducing the adhesive force of the toner to the photoreceptor. However, since no improvement has been made for the blade, the blade has passed through the brush and reached the blade. The toner is insufficiently inhibited by the blade, and the time until the phenomenon occurs is delayed, but the filming is insufficiently improved.
The filming phenomenon involves the surface roughness, hardness, cleaning blade, toner, and the like of the photoconductor. Next, these will be described.
[0029]
1. Photoreceptor surface roughness
The surface roughness of the photoreceptor, when the friction coefficient of the photosensitive layer is low, the smaller the surface roughness, the higher the adhesion of the blade, but the higher the degree of adhesion, the higher the frictional resistance with the photoreceptor, Since the blade is easily deformed, the probability of occurrence of toner loss increases. Therefore, as long as good image quality is obtained, it is desirable that the surface roughness is large enough to prevent toner loss.
The surface roughness of the photoreceptor has a 10-point average roughness Rz. _JIS And items such as maximum height Rz, but 10-point average roughness Rz _JIS In the case of (1), the image quality such as resolution and sharpness, and the maximum height Rz have a great significance in the cleaning performance of the small particle size toner.
As the toner, a pulverized toner having an average particle diameter of about 4 to 8 μm and an average circularity of about 0.91 to 0.94, or a polymerized toner having an average particle diameter of about 0.96 to 1.0 is used. For example, a pulverized toner having an average particle diameter of 4 μm includes toner as fine as about 1 μm, so that the surface roughness of the photoreceptor must be at least 1 μm or less. If the maximum height Rz of the unused photoreceptor is 1 μm or more, there is a possibility that toner is missing from the first copy even if the blade is not twisted. However, in fact, since the valley of the surface is filled by the blade edge twisting due to the blade pressing, even if the maximum height Rz is 1 μm or more, the toner is not necessarily immediately removed, but it cannot be suppressed. In this case, the toner may come off, and when the toner is twisted, the toner comes off at a level close to 100%.
[0030]
The following disclosure is an example in which the ten-point average roughness Rz is defined.
A rubber plate having a JIS-A hardness of 55 to 75 degrees and a rebound resilience of 30 to 70% in a 1 to 5 mm plate shape is brought into contact with the photoreceptor, and the photoreceptor has a surface roughness of 10 points and an average roughness Rz of 0. By setting the thickness to 0.2 to 2.0 μm, preferably 0.3 to 1.5 μm, it is possible to prevent the toner from slipping through even if the blade is turned up (for example, see Patent Document 8).
[0031]
[Patent Document 8]
JP-A-11-212412 (Claims 1 to 3 on page 2, column 1, line 2 to line 22)
[0032]
If the frictional resistance between the photoreceptor and the cleaning blade is kept low, deformation of the blade is unlikely to occur, but if it is high, the stick-slip phenomenon of the blade is liable to occur, and it is about 1 to 2 μm from the site where the distortion or turning over occurs. A phenomenon in which minute toner comes off occurs, which causes filming.
It is expected that the friction resistance between the photoreceptor and the blade is increased because no lubricant is applied to the above disclosed example. Therefore, when a blade having a low hardness of 55 to 75 degrees is used, the adhesion to the photoreceptor is enhanced, but distortion and crushing are liable to occur in a region where the friction coefficient is high, and a gap is formed between the photoreceptor and When the toner is used, there is a high possibility that the toner may pass through.
[0033]
2. Photoconductor surface hardness
If the surface hardness of the photoreceptor is low, filming is unlikely to occur because the photoreceptor is easily worn, but the photoreceptor layer is worn out, shortening the life of the photoreceptor. Produce rationality. Therefore, in order to extend the life of the photosensitive member, it is desirable that the photosensitive layer has a high hardness.
The reason for increasing the surface hardness of the photoconductor is to not only prolong the life of the photoconductor but also to reduce the bite of the cleaning blade into the photoconductor layer, to reduce the increase in frictional resistance, and to suppress the deformation of the blade.
[0034]
As described above, the organic photoreceptor has a single-layer structure in which the functions of the charge generation material and the charge transport material are integrally formed in the photosensitive layer, and a two-layer structure of the charge generation layer and the charge transport layer. There is a function-separated type photoreceptor, and the present invention uses the latter function-separated type photoreceptor. A general function-separated type organic photoreceptor has a configuration in which a charge generation layer is formed directly on a conductive support or through an undercoat layer (or an intermediate layer), and then a resin layer containing a charge transport material (charge transport layer). Layer) is formed.
On the other hand, as a binder resin material which is a constituent material of the charge transport layer, a polycarbonate resin material (A type, C type, Z type, etc.) having high resistance, high transparency, and little polarity dependency is preferably used. . The polycarbonate resin alone has high hardness and high abrasion resistance, but the photosensitive layer using the polycarbonate resin has a Vickers hardness of 10 to 30 kg / mm. ² The pencil hardness is reduced to about B, and the tensile strength is also reduced. On the other hand, corona products such as ozone and nitrogen oxides (NOx) generated at the time of charging tend to adhere, and the free surface energy (or friction coefficient) decreases. Therefore, the friction resistance with the cleaning blade is increased, so that the photosensitive layer is liable to be scratched and easily worn. Further, high frequency noise (vibration noise) may be generated by the rubbing of the cleaning blade.
[0035]
When the thickness of the photosensitive layer decreases, the capacitance increases, and the charge level decreases. For this reason, when the potential difference between the charged position and the developing bias potential is reduced, background contamination is likely to occur.
If the potential difference between the developing bias potential and the charged portion is increased to prevent background contamination on the copy, the potential difference between the developing bias potential and the image portion potential is inevitably reduced. Lower. For these reasons, the durability of the organic photoreceptor is as short as about 50,000 to 80,000.
Due to the low endurance number of sheets, a user who has a large number of copies frequently exchanges the photoconductor and members related thereto. Therefore, it is necessary to stabilize image quality by suppressing wear.
[0036]
Factors that affect the number of durable sheets include the image area of the document, the rubbing of the cleaning member and the developer, the pressing of the toner, carrier, and paper powder by the cleaning member, and the corona product generated during the above-described charging. When the photosensitive layer is worn, the electrostatic capacity is increased, so that the charged position is reduced. Therefore, the margin between the charging potential and the developing bias potential is reduced, and the possibility of background contamination is increased.
In a quadruple tandem type color copier, the wear of the four photoconductors varies depending on the color of the original, the image area, the amount of developer supplied, the amount of toner, and the like, in addition to the background contamination, so that the color uniformity is improved. And color reproducibility.
Improving the abrasion resistance of the photoconductor assures a reduction in total cost and reliability with respect to image quality. Therefore, it is important to increase the durability of the photoconductor.
Techniques for increasing the durability of the photoreceptor include a method of forming a wear-resistant thin film on the surface of the photoreceptor, a method of forming the photosensitive layer with a wear-resistant photosensitive material, and making the outermost surface of the photosensitive layer wear-resistant. There are methods.
[0037]
There are several disclosed examples of the means for improving the durability.
It is described that the photosensitive layer is composed of a photosensitive layer in which conductive fine particles such as zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, and tin-doped indium oxide are dispersed (for example, see Patent Documents 9 and 10). .).
[0038]
[Patent Document 9]
Japanese Patent Application Laid-Open No. 06-035220 (Claims 1 and 2 on page 2, column 1, line 2 to line 14)
[0039]
[Patent Document 10]
JP-A-08-234469 (Claim 1 on page 2, column 1, line 2 to line 12)
[0040]
Abrasion resistance can be improved by dispersing an appropriate amount of conductive particles having high hardness in the photosensitive layer. The use of low-resistance fine particles is effective for charge injection charging, but when a hazardous contact charging method is used, image deletion is likely to occur, and it is difficult to achieve both resistance to image quality deterioration.
[0041]
0.02 to 5 μm (preferably 0.07 to 2.0 μm) inorganic compound particles, for example, metal oxides such as silica, aluminum oxide, zinc oxide and aluminum nitride, metal sulfides, metal nitrides and butadiene-based charges It is described that the photosensitive layer comprises a photosensitive layer containing a transport material (for example, see Patent Document 11).
[0042]
[Patent Document 11]
JP-A-08-123053 (page 3, column 3, line 42 to line 49)
[0043]
This means can improve abrasion resistance and secure charging ability by dispersing high-resistance inorganic compound particles other than silica in the photosensitive layer. When the butadiene-based charge transporting material is contained in the photosensitive layer, the mobility of the charges can be maintained in the same manner as in the charge transporting layer. However, since trap sites are easily formed between the particles and the binder resin, the residual potential is accumulated due to repeated use, and light attenuation is deteriorated due to repeated use, and image density may gradually decrease and image unevenness may occur. . Also, when a filler having a large particle diameter is used, the sharpness of a line image is reduced. On the other hand, the surface roughness of the photoconductor is increased, and the difference between the maximum value and the minimum value is larger than the particle diameter of the toner. Cleaning failure. Further, there is a problem that the edge of the cleaning blade is easily deformed, and the cleaning of the toner and the corona product is likely to be defective.
When silica is used, the oxidizing action of ozone causes a rapid decrease in the resistance of the photosensitive layer, and causes image deletion even in a normal humidity environment of about 60% RH. A heat source for heating to a certain degree is necessarily required.
[0044]
Silicone resin, phenolic resin, SiO 2 having a particle size of 1 to 3 μm is formed on the charge transport layer having a thickness of 12 μm or less. ₂ (Silica), Al ₂ O ₃ (Alumina), TiO ₂ (Titanium oxide) and a photosensitive layer in which ZnO (zinc oxide) is dispersed are described (for example, see Patent Document 12).
[0045]
[Patent Document 12]
JP-A-08-234455 (Page 4, column 6, line 26 to page 5, column 7, line 21)
[0046]
This means is to achieve high abrasion resistance by using a filler having a large particle diameter.However, since the particle diameter of the particles is large, the surface roughness of the surface layer of the photoreceptor becomes large, and the sharpness of the image edge is reduced. Lacking. Further, when the blade cleaning method is used, the edge is distorted, toner is lost, and the image quality of the copy paper is likely to be reduced and the background is easily stained. Furthermore, the blade edge is insufficient, and the durability of the cleaning blade cannot be maintained.
[0047]
It is described that a photosensitive layer in which fine particles of an inorganic compound such as titanium oxide, aluminum oxide, and silicon oxide having an average particle diameter of 0.02 to 0.5 μm are dispersed in one or two kinds of polycarbonate resins ( For example, see Patent Document 13.) Further, it is described that, in image formation using a photoreceptor containing inorganic fine particles such as silica of 0.05 to 2 μm in a re-surface layer, residual toner is cleaned and removed by a rubber blade and a brush-like cleaning member ( For example, see Patent Document 14.)
[0048]
[Patent Document 13]
JP-A-08-146641 (Claim 1 on page 2, column 1, line 2 to line 8, claim 2 on column 2, line 31 to line 42)
[Patent Document 14]
JP-A-8-314175 (Claims 1 to 4 on page 2, column 1, line 2 to line 14)
[0049]
Since these means use a filler having a small particle diameter, deterioration of image quality due to particles is small, and high durability can be achieved. However, when silicon oxide is used, almost 100% of image deletion occurs due to low resistance due to ozone. In a region where the particle size is small (for example, 0.1 μm or less), the particle size is too small, so that it becomes difficult to improve the wear resistance. By increasing the amount of addition, the durability can be increased, but simply increasing the amount causes an increase in the residual potential, thereby deteriorating the image quality.
[0050]
A photosensitive layer having a surface roughness of 0.1 to 0.5 μm formed on a conductive support having a surface roughness of 0.01 μm to 2 μm is coated with inorganic fine particles (hydrophobic particles) having an average particle size of 0.05 to 0.5 μm. (Patent Document 15) describes dispersing silica (chemically treated silica) over a thickness of 0.05 to 15 μm.
[0051]
[Patent Document 15]
JP-A-08-248663 (Summary of the first line to the last line of the lower left column on page 1)
[0052]
This means makes the dispersed silica particles hydrophobic, thereby increasing durability and preventing a decrease in resolution and image deletion caused by the attachment of contaminants such as corona products.
Although the effect of repelling water droplets (large contact angle) is exhibited by making the inorganic fine particles hydrophobic, the adhesion of the corona product cannot be prevented, so that the image deletion cannot be prevented. In addition, the inorganic fine particles that have been subjected to the hydrophobic treatment that has come out of the surface of the photosensitive layer are rubbed by a blade or the like, and the coating is scraped, and the resistance of silica is reduced by the action of ozone. Impossible.
[0053]
3. Cleaning device (cleaning brush and cleaning blade)
The cleaning device includes a cleaning brush, a cleaning blade alone, and a cleaning brush and cleaning blade combined type. Each has advantages and disadvantages, and can be used properly depending on the developer, photoreceptor, copy amount, and the like to be used.
Cleaning brushes are roughly classified into either straight-haired brushes (for example, see Patent Literatures 16, 17, 18, and 19) and loop-shaped brushes (for example, see Patent Literatures 20 and 21). Also, a type in which both straight hairs and loops are used (for example, see Patent Document 22) has been proposed.
[0054]
[Patent Document 16]
Japanese Patent Application Laid-Open No. 7-155222 (claims on page 2, column 1, line 1 to line 8; FIGS. 1, 3)
[Patent Document 17]
JP-A-6-236134 (Claim 1, FIG. 4 on page 2, column 1, line 2 to line 13)
[Patent Document 18]
Japanese Patent Application Laid-Open No. 9-22155 (FIG. 1)
[Patent Document 19]
JP-A-11-167224 (FIG. 5)
[Patent Document 20]
Japanese Patent No. 2793647 (Claims on page 1, column 1, line 1 to line 13; FIG. 3)
[Patent Document 21]
Japanese Patent No. 2619424 (Claims in the first to seventh lines of page 1, page 1, column 1, FIG. 3)
[Patent Document 22]
Japanese Patent No. 2,868,539 (Claim 1, FIG. 4 on page 1, column 1, line 2 to line 13)
[0055]
Each of the brush shapes has a function of removing foreign matters such as toner and paper dust which are difficult to remove from the photoreceptor with a blade, but cannot remove foreign matter firmly fixed like filming. Nylon-based, polyester-based, acrylic-based fibers, carbon fibers, and the like are used as the brush material. A straight-haired brush has a problem of hair falling, and there is a problem that the cleaning property deteriorates as the brush is used.The cleaning of a loop-shaped brush is better than that of a straight-haired brush. And there is a problem that cleaning is reduced due to clogging. The combined use of a cleaning brush and a cleaning blade is an effective means for increasing the cleaning ability.
[0056]
On the other hand, in the case of a cleaning blade, there are two methods in which one cleaning blade is installed in a reverse rotation direction (counter) or a forward rotation direction (leading) with respect to the rotation direction of the photoconductor.
The blade cleaning method is simpler than the brush method, and is an advantageous method for reducing the size of the image forming apparatus. Therefore, the blade cleaning method is employed in most image forming apparatuses. In the blade cleaning method, if the blade is installed in the counter direction with respect to the rotation direction of the photoconductor, the bite into the photoconductor increases, and the cleaning performance of the toner can be improved.
[0057]
The cleaning blade has a rebound resilience of 30 to 60% and a rubber hardness (JIS-A hardness) of 50 to 90 degrees, for example, a JIS-A hardness of 60 to 85 degrees (see Patent Document 23). , With a JIS-A hardness of 50 to 90 degrees (see Patent Document 24), a JIS-A hardness of 50 to 80 degrees (see Patent Document 25), etc. ) A rubber blade is used by attaching it to a plate-like support base made of aluminum or iron.
[0058]
[Patent Document 23]
Japanese Patent Application Laid-Open No. 08-248851 (Claim 1 on page 2, column 1, line 2 to line 9)
[Patent Document 24]
JP 2001-242758 A (page 4, column 5, line 16 to column 6, line 17)
[Patent Document 25]
JP-A-2002-055582 (page 4, column 5, line 50 to column 6, line 11)
[0059]
Polyurethane rubber used as a blade material for cleaning residual powder such as toner has high durability and extremely good adhesion to an organic photoreceptor, and therefore has high cleaning performance. However, since the adhesiveness is high, the frictional resistance with the photoreceptor is increased, and the photosensitive layer is easily worn. In addition, when the contact portion of the blade is dragged in the rotation direction of the photoconductor, the blade is twisted, and if the twist is constantly continued, the restoration is not sufficient. On the other hand, when dragged sufficiently, a gap is formed, so that the resistance becomes light and returns to the original position, a so-called stick-slip phenomenon occurs.
When the stick-slip phenomenon occurs, a small gap is created when the blade goes and returns, and toner escapes from the gap, but when it always occurs at the same position, the blade deforms and constant toner escape occurs, A streak-like filming occurs at the part that has escaped.
In order to clean toner satisfactorily, it is necessary to prevent the edge of the cleaning blade from vibrating due to rotation, to prevent the edge of the blade from being dragged by the photoreceptor, and to press the toner by the blade. It is important not to make room (the blade should be in line contact with the photoreceptor as much as possible during driving, rather than in surface contact).
[0060]
4. toner
In an image forming apparatus, a one-component developer or a two-component developer in which toner and a carrier are mixed in an appropriate amount is used to visualize an electrostatic latent image formed by charging and image exposure. . The developing method includes a magnet brush developing method, a spray developing method, a cascade developing method, a flying developing method, and the like, and the mainstream is a magnetic brush developing method.
As the carrier used for the two-component developer, a resin-coated magnetic powder of about 30 to 80 μm containing a charge control agent such as iron powder, ferrite, and magnetite is used. When the particle size is small, high resolution is easily obtained, but when the particle size is too small, the electrostatic force of the photoconductor overcomes the magnetic field of the developing device and the carrier easily adheres to the photoconductor. Can be disturbed, causing image omission or damaging the photoreceptor.
Therefore, it is necessary to select a carrier suitable for the copying system.
On the other hand, in recent years, with the spread of full-color copying machines (image forming apparatuses such as electrophotographic copying machines and printers), higher definition and higher image reproducibility have been increasingly required, and the average particle size has been increasing. However, in recent years, polymerized toner having high sphericity has come to be used due to the demand for higher image quality. The particle size distribution of the pulverized toner is as large as ± 3 to 4 μm, and there are many fine particles of about 1 to 2 μm, which is disadvantageous in terms of S / N, transferability, sharpness, etc., but the cleaning property is relatively good. It is. However, when a large amount of fine particles is contained, there is a large problem that the fine particles may cause toner dropout depending on the surface roughness of the photoconductor. On the other hand, the polymerized toner has a relatively small particle size of about ± 0.5 to 1 μm, and is superior to the pulverized toner in terms of image quality and transferability.
[0061]
The toner production method mainly includes a pulverization method and a polymerization method.
The pulverization method is a method in which additives such as a colorant and a charge control agent are melted and kneaded in a binder polymer produced by polymerization, and the resulting mass is roughly pulverized, finely pulverized, and classified by a sieve. Although the pulverization method has an advantage that the toner can be finely divided, the cost is likely to be high because the process is complicated.
The toner produced by the pulverization method has an irregular shape with many irregularities (irregular shape). A rounding step is further added to obtain a toner for a developer, and the particle size is sieved by classification. In a commonly used toner, the circularity of the toner is as small as about 0.91 to 0.94 (square), so that it is difficult to uniformly charge the particles and easily cause transfer failure. In addition, when pressed against the photoreceptor by the cleaning blade, there is a tendency that scratches easily occur.
In addition, even if a high resolution with good sharpness is obtained in the early stage, it is difficult to maintain, and when a copy of a copy (the second or third generation copy) is printed, the resolution becomes extremely poor, and it is not practical. There are points. For this reason, toners with even higher sphericity are being developed, but the cost is further increased, and conversion to polymerization methods is being promoted.
[0062]
The main production methods of the polymerization method include a suspension polymerization method and an emulsion polymerization method. For example, in the case of the suspension polymerization method, a binder resin is produced by homogenizing additives such as a colorant and a charge controlling agent, adding a dispersion medium and a dispersant, and polymerizing. Since the polymerization method has a simplified process, the production cost is lower than that of the pulverization method. In addition, there is an advantage that the particle diameters are relatively well uniform, and irregularly shaped particles are hardly produced (mostly spherical toner).
Most of the particles produced by the polymerization method have a spherical shape close to a true sphere, and have relatively uniform particle diameters. Therefore, it is easy to make charging uniform and adhere to a latent image almost faithfully. Therefore, the transfer efficiency is as high as 99% or more, high resolution can be easily obtained, and dot image reproducibility is high.
For this reason, in recent years, there are many examples in which a toner manufactured by a polymerization method having many advantages is used.
[0063]
The spherical toner produced by the polymerization method has a circularity of about 0.96 to 1.0, which is almost spherical or spherical, so that it easily penetrates under the blade, and the blade cleaning method tends to cause poor cleaning.
Conventional cleaning blades that have been used with conventional pulverized toners use a relatively soft rubber blade with a blade hardness of about 60 to 80 degrees. At the same time, the blade edge is distorted. Further, since the friction coefficient of the photoconductor is high, the tip of the blade is caught in the photoconductor and deformed. For this reason, a slight gap is generated between the blade and the photoconductor, to the extent that the toner escapes, and the toner staying on the cleaning blade passes through the gap between the blades, so-called toner loss occurs. This is especially true when the surface roughness of the photosensitive member is large due to scratching, filming, or the like.
This toner loss tends to be more severe for a spherical toner having a small circularity and a small degree of catch.
In a cleaning device in which the contact pressure of the blade is set to a small value, the cleaning is hardly performed in some cases, and the photoconductor having a softer surface layer of the photoconductor is more difficult to perform cleaning.
[0064]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to start with the photoreceptor surface state, the twist of the blade edge due to the high friction coefficient of the photoreceptor surface, the size of the photoreceptor surface roughness, toner particle morphology, corona product, and An image forming apparatus, an image forming method, and a process cartridge that can suppress the generation of filming caused by the action of residual powders (paper powder, toner constituents, etc.) and maintain S / N and good image quality with good resolution. It is to provide.
[0065]
[Means for Solving the Problems]
Spherical toners having a high average circularity, particularly spherical toners having a high circularity of 0.98 to 1.0, are apt to sink under the blade of a cleaning blade designed for pulverized toner, and to cause poor cleaning. On the other hand, in the case of the pulverized toner, toner having a small particle size of about 1 to 2 μm mixed with the pulverized toner of about 4 to 6 μm has a small gap of 2 to 3 μm or less generated between the blade and the photoconductor, When the surface roughness of the photoreceptor is larger than the toner diameter, the photoreceptor slips under the blade and slips through.
If such a slip-through phenomenon is continuously continued, corona products and paper powder are mixed, and the photoreceptor is gradually filmed, and the image quality gradually deteriorates as the photoreceptor proceeds.
[0066]
In order to avoid the filming phenomenon, it is necessary to make toner slip through to zero, but it is actually quite difficult. For example, if the surface of the photoreceptor has a locally high level of friction coefficient (due to the adhesion of corona products, toner components, binder resin of the transfer receiving body, etc.), the blade edge is distorted at that site, and toner is removed. Is more likely to occur. In addition, even if there is no toner removal from the blade, even if toner is slightly scattered from the developing sleeve, the toner attached to the photoreceptor causes filming.
Therefore, as a result of earnestly studying the means for solving this filming, it was found that the above-mentioned problem can be achieved by taking the following method.
[0067]
By setting the surface roughness of the photoconductor surface layer smaller than the minimum particle size of the toner, the toner is prevented from spontaneously falling out. Further, by applying a lubricant to the surface layer of the photosensitive layer (performed by means of an external addition method or an internal addition method), the formation and enlargement of unevenness on the surface layer of the photosensitive layer are prevented. The lowering of the friction coefficient due to the lubricant and the wear resistance of the photosensitive layer due to the addition of the filler prevent unnecessary shaving. Further, the friction coefficient due to the lubricant is reduced, the adhesion of the toner to the photosensitive layer is reduced, and the cleaning property is improved. In addition, a cleaning device consisting of a cleaning brush with improved mechanical strength and a cleaning blade cleans residual powder on the photoreceptor and removes adhering foreign matter by polishing the photoreceptor surface as much as necessary. In addition, filming is prevented from being formed on the surface of the photoconductor.
As a result of these measures, there is no foreign matter attached to the photoconductor surface layer and there is no coefficient of friction, so that the photoconductor surface layer is always kept clean.
Therefore, a reduction in electrophotographic characteristics such as image deletion, resolution reduction, and charging characteristics is avoided, and stable image quality with good S / N can be provided until the life of the photoreceptor.
[0068]
That is, the above object is achieved by (1) applying a voltage to a charging member constituting a charging device disposed to face the electrophotographic photosensitive member to uniformly charge the electrophotographic photosensitive member, Forming an electrostatic latent image by optical writing from an image exposure device, visualizing the electrostatic latent image with a developing device, transferring the electrostatic latent image to a transfer target by a transfer device to which a voltage is applied, a cleaning brush and a cleaning blade In the image forming apparatus using indirect electrophotography, which forms an image by cleaning the residual powder on the photoreceptor by using the cleaning device composed of: _JIS Applying a lubricant to the surface of the electrophotographic photosensitive member having a height of 0.3 to 1.0 μm and a maximum height Rz of 0.4 to 1.5 μm, and simultaneously operating a cleaning brush and a cleaning blade. Image formation is performed by maintaining the average wear amount (t) of the photosensitive layer per 10,000 sheets (in terms of an electrophotographic photosensitive member of φ30 mm) within a range of 0.1 μm ≦ t ≦ 0.5 μm. Image forming apparatus ", (2) wherein the cleaning brush has a loop brush composed of any one of polyester fiber, nylon fiber and acrylic fiber fixed on a metal core, (3) The image forming apparatus according to (1), wherein a cleaning brush is installed in the cleaning device such that the cleaning brush makes uniform surface contact with the electrophotographic photosensitive member. "The means for fixing the loop brush on the metal core is such that the strip-shaped loop brush is spirally wound around the metal core without any gap, and the cleaning brush is a cleaning blade of the cleaning blade. (1) The image forming apparatus according to the above (1) or (2), wherein the image forming apparatus is disposed in the cleaning device so as to be in uniform surface contact with the electrophotographic photosensitive member. (4) The image forming apparatus according to any one of the above items (1) to (3), wherein a resin is applied to a surface of the cleaning brush that comes into contact with the photoreceptor and an internal direction. (5) The image forming apparatus according to (4), wherein the application of the resin to the surface of the cleaning brush that contacts the photoconductor and to the inside thereof is performed by an immersion method. " 6) The image forming apparatus according to any one of the above items (1) to (5), wherein a flicker bar is not attached to the cleaning brush. The above (1) to (6), wherein the rotation of the electrophotographic photosensitive member is rotated in a forward direction, and the powder remaining on the electrophotographic photosensitive member is cleaned by rubbing. Item 8), wherein the photosensitive layer constituting the electrophotographic photosensitive member comprises a charge generation layer and a charge transport layer, and the charge transport layer further comprises an inorganic filler containing no inorganic filler. A non-dispersed charge transport layer and an inorganic filler-dispersed charge transport layer, wherein the inorganic filler having an average particle size of 0.3 to 0.7 μm is contained in the inorganic filler-dispersed charge transport layer; 20. An image forming apparatus according to any one of the above items (1) to (7), characterized in that it contains at least 20% by weight and at most 35% by weight. Or a polytetrafluoroethylene (PTFE) lubricant is applied directly or indirectly to the surface layer of the electrophotographic photosensitive member using a coating means to reduce the friction coefficient, and The image forming apparatus according to any one of the above items (1) to (8), wherein the coefficient of friction measured by the method is 0.20 to 0.45 at the time of image formation. ”, (10) (1) through (9), wherein the charging of the electrophotographic photosensitive member at the time of forming the electrostatic latent image is performed by surface contact of the charging member with a nip on the electrophotographic photosensitive member. The image forming apparatus according to any one of the above items. (11) "Charging of the electrophotographic photosensitive member at the time of forming an electrostatic latent image is performed by keeping the charging member and the electrophotographic photosensitive member in a non-contact state with a distance of 30 to 100 [mu] m. (12) "The image forming apparatus according to any one of the above items (1) to (11)". An image forming method by an indirect electrophotographic method, wherein an image is formed using an electrophotographic photoreceptor, a charging device, a cleaning device including a cleaning blade and a cleaning brush, and a lubricant applying unit, (13) “The electrophotographic photosensitive member, the charging device, the developing device, the cleaning brush, and the cleaning blade used in the image forming apparatus according to any one of the above items (1) to (11). The process cartridge is characterized in that at least one unit selected from a cleaning device and a lubricant applying member is integrally supported and is detachably attached to the image forming apparatus main body.
[0069]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1. Image forming equipment and copying process
A copying process using the indirect electrophotographic method of the present invention will be described with reference to FIG. 1 or FIG.
FIG. 1 is a schematic view of a copying apparatus using a single color toner in which one photosensitive member is combined with one developing device. The photosensitive member is charged by a charging member using a roller or a non-contact charging method. Is shown in FIG. FIG. 2 shows a lubricant application device (200) ((201) denotes a lubricant, and (202) denotes an application brush) for applying a lubricant to the surface layer of the photoconductor in FIG. FIG.
Although not shown, a damping member for suppressing a vibration sound (high-frequency sound) generated when an AC voltage is superimposed on the charging device can be incorporated in the photoconductor.
[0070]
As shown in FIG. 1, the basic configuration of a general copying process is centered on a photoreceptor (1), a charging device (2), an image exposing device (3), a developing device (4), a transfer device (5), Separating device (6), cleaning device (7) (cleaning device (7) is composed of cleaning brush (7-1) and cleaning blade (7-2)), fixing device (8) and copy paper (9) Consists of
The photoreceptor (1) used in the present invention has a constitution in which an undercoat layer and a photosensitive layer are formed on a drum-shaped conductive support, and the photosensitive layer further comprises a charge generation layer and a charge transport layer. .
In the charge generation layer, sufficient electrons and hole pairs are generated by light irradiated by the image exposure device (3), and are separated according to the surface charge and the charge of the support. As long as it does not form a high barrier such that holes cannot jump over the interface between the charge generation layer and the charge transport layer when moving toward the negative charge of the surface layer of the inorganic or organic type, Can be used.
[0071]
On the other hand, the charge transporting layer of the photoreceptor used in the present invention has a filler non-dispersed charge transporting layer in which no filler is dispersed and a total weight of 0.3 to 0.7 μm α-alumina in which the filler is dispersed. It is composed of two layers of an inorganic filler-dispersed charge transport layer dispersed in an amount of 20% by weight or more and 35% by weight or less.
The reason for dispersing the filler is to improve the wear resistance of the photoreceptor and to reduce the edge of the blade by reducing the penetration of the cleaning blade into the photosensitive layer. The reason for this is to achieve abrasion resistance, eliminate obstacles to accumulation of residual potential, diffusion of light, and charge transfer, and to prevent image deterioration.
The filler dispersed in the filler-dispersed charge transport layer has a high hardness, a uniform granularity, a low hygroscopicity, and an electric resistance of 10%. ¹² Ω · cm or more, 10 ¹⁴ An inorganic filler of Ω · cm or less is desirable, and α-alumina is one of the most suitable materials.
The surface roughness of the photosensitive layer tends to be rough and large as the particle size of the filler increases.
Also, the copying tends to roughen the surface and increase the surface roughness. Therefore, in order to prevent the occurrence of cleaning failure, it is important to manage the surface roughness so that it does not become larger than the toner particle size. It is considered that the roughness of the surface roughness is mainly caused by agglomeration of the toner in the developer and hard foreign substances such as the carrier, talc and resin in the paper powder, and metal powders other than the above-described ones sneaked under the cleaning blade. . Specifically, the ten-point average roughness Rz including aging _jis Is desirably suppressed to 0.3 to 1.0 μm and the maximum height Rz to 0.4 to 1.5 μm.
This is to prevent the surface of the photoreceptor from being roughened (for example, scratches caused by fillers, toner, paper powder, carriers, etc. added to the photoreceptor), thereby preventing the blade from floating and causing toner to escape through the floating portion. is there. Another reason is to minimize the possibility that contaminants such as corona products enter into the recesses between the peaks and are difficult to be removed by the blade. In the present invention, as shown in FIG. 2, a lubricant is applied to the surface of the photoreceptor by an external addition method. However, when the lubricant enters the depression first, the corona product enters the depression. Can be avoided. As a means for applying a lubricant to the photoreceptor, a method of applying the lubricant using a specific device as shown in FIG. 2, a method of adding a lubricant to the toner, and applying a lubricant to the surface There is a method of adding 10% internally.
[0072]
The reason for forming an image by adding a lubricant is that, first, the friction coefficient of the photosensitive layer is reduced so that twisting of the blade is less likely to occur. Thirdly, it is to reduce toner adhesion to the photoreceptor and to achieve good cleaning performance.
Fourth, the dents are filled with a small amount of lubricant to prevent toner from slipping through. Fifth, in order to reduce the room for corona products to enter, and to avoid deterioration in image quality. It is.
[0073]
By adding a small amount of a lubricant for reducing the coefficient of friction to the surface of the photoreceptor, distortion of the blade edge can be reduced, and toner loss can be improved. Further, since the adhesion of the toner to the photoreceptor is reduced, the transfer efficiency is improved, the phenomenon such as missing characters is eliminated, the cleaning property is improved, and the S / N of the copy quality can be improved. Excessive application (for example, when the pressure of the brush in contact with the lubricant is too high) affects image quality, but application of a small amount of lubricant does not affect charging characteristics and image characteristics. .
[0074]
In order to form an image, the photoconductor (1) is charged by a charging device (2). It is desirable that the contrast potential be at least 250 V or more in order to obtain good image forming properties, and the charging potential for that purpose is preferably -400 V to -800 V.
Although FIG. 1 shows an example of a charging roller as a charging member, a charging member such as a brush or a blade may be used. There are two types of charging methods, a contact charging method and a non-contact charging method, and any of these methods can be used in the present invention.
[0075]
In the non-contact charging method in which charging is performed while maintaining a small gap between the charging member and the photoconductor, the gap between the charging member and the photoconductor is preferably 30 μm or more and 100 μm or less, and more preferably 50 to 80 μm. Is desirable. By separating the charging member from the photoreceptor, the wear caused by the charging member becomes difficult to reduce, and when toner is removed from the cleaning blade, the charging member becomes less contaminated with toner, and the margin for discharge breakdown is reduced. to be born.
The contact charging method has a smaller margin for toner contamination and discharge breakdown of the charging member than the non-contact charging method.However, since the gap is 0 μm, the applied voltage can be set lower. There is an advantage that the generation amount is reduced.
A high voltage power supply is connected to the charging member, and a DC voltage or a DC voltage on which an AC voltage is superimposed is applied. In both contact charging and non-contact charging, charging is performed according to Paschen's law, the charging start voltage Vth is the lowest at the time of contact charging, and the starting voltage Vth increases as Gap increases. The application conditions for setting the charging voltage to −400 to −800 V are as follows: in the case of DC voltage driving, the application condition to the charging member is −1000 V to −2000 V, and in the case of DC voltage driving in which AC voltage is superimposed, DC is applied. The voltage is set to -450 to -900 V, and the AC voltage (sine wave, triangular wave) is set to 700 V to 2000 V / 800 to 2500 Hz. The application of the DC voltage on which the AC voltage is superimposed is intended to prevent uneven charging and uneven image formation when there is a gap between the photosensitive member and the charging member. The DC voltage is set to a DC voltage obtained by superimposing an AC voltage of Peak to Peak voltage twice or more of the charging start voltage Vth on a DC voltage equivalent to or slightly higher than that of the charging start voltage Vth.
[0076]
The roller type charging member is covered with an elastic member using a SUS round bar of φ5 to φ15 mm as a core metal. The elastic member for charging the photoreceptor is made of hydrin rubber alone or urethane rubber or hydrin rubber, to which a resistance controlling material such as conductive carbon, carbon fiber powder, or ionic conductive agent is added. Add a liquid agent to increase the specific resistance to 10 ⁵ -10 ¹⁴ The one adjusted to Ω · cm is used. Specifically, the electric resistance of the surface of the contact charging member and the surface of the non-contact charging member facing the photoreceptor can be changed depending on the charging method.
[0077]
For the non-contact charging member, the outermost surface is 10 ⁵ -10 ⁸ Ω · cm, 10 for contact charging member ¹² -10 ¹⁴ Ω · cm. This is because the gap between the charging member and the photoreceptor causes the charging start voltage Vth to shift to the higher side, resulting in a difference in charging properties. For uniform charging, it is necessary to lower the volume resistance of the charging member. There is. However, if it is lowered too much, it may cause discharge breakdown. ⁵ Desirably, it is Ω · cm or more.
Furthermore, the surface roughness of the charging member is 10 points average roughness Rz compared to the contact charging member. _jis Is preferably about 50 to 200 μm, which is advantageous for improving uniform charging and charging efficiency. An elastic member having a hardness of about 30 to 90 degrees in JIS-A hardness is used.
[0078]
In the case of the contact charging method, it is desirable to increase the nip (1 to 5 mm) in order to increase the charging efficiency. Therefore, an elastic member having a low hardness is used as the contact charging member. Is not obtained, the charging efficiency is degraded, but there is an advantage that the hardness is not limited to the hardness of the charging member used.
The final external dimensions are set according to the system conditions, but are usually about φ10 to φ20 mm.
[0079]
The charged photoreceptor (1) receives one or a plurality of LD (Laser Diode) elements or a digital image transmitted from a personal computer or the like on a document image read by a CCD (Charge Coupled Device) or An image image exposure device (3) including an LED (Laser Emitting Diode) array, a convex lens, a polygon mirror, a cylindrical lens, etc. irradiates a single-wavelength light image narrowed down to a dot diameter of about 60 to 20 μm, and receives an input signal. An electrostatic latent image corresponding to the image is formed. As the LD element or the LED array, an element having an oscillation wavelength in or near the highest sensitivity region of the photoconductor is selected. Since the spot diameter can be narrowed as the oscillation wavelength becomes shorter, an LD element having an oscillation wavelength on the short wavelength side of about 400 to 450 nm is advantageous in obtaining a high resolution such as 1200 or 2400 dpi. It can be used mounted on a forming apparatus.
[0080]
To visualize the electrostatic latent image formed on the photoreceptor (1), a developing device (4) using a one-component toner (magnetic toner) or a two-component developer composed of a toner and a carrier is used. However, in the present invention, a two-component developer is used.
Carriers of the two-component developer include, for example, polyfluorocarbon, polyvinyl chloride in order to improve chargeability, charge stability, durability and the like of powders (magnetic powder) having magnetism such as iron, ferrite, and nickel. And those coated with a resin such as polyvinylidene chloride. The particle size of the carrier is about 30 to 60 μm.
The particle size of the carrier affects the resolution, and the smaller the carrier, the better the resolution. However, if the carrier is too small, the carrier is attracted by the electrostatic force of the photoconductor and easily adheres to the photoconductor. Therefore, if a transfer failure (transfer loss) of the toner image occurs or the toner image is transported to the cleaning unit, the blade is pressed against the photoconductor, thereby damaging the surface of the photoconductor, increasing the surface roughness, deteriorating the image quality, and causing unevenness of the image. The corona product may enter the portion, which may cause image deletion or shorten the durability of the photoreceptor.
[0081]
On the other hand, the toner may be a toner manufactured by the above-described pulverization method and having a spherical shape by shaving off an angular area, or a spherical toner manufactured by a polymerization method (emulsion polymerization method, suspension polymerization method, etc.). A toner having an average particle size of 4 to 8 μm is used, and 2 to 10 (% by weight) is mixed with the carrier.
The particle size of the toner also affects the resolution similarly to the carrier. However, if the particle size is too small, there is a concern that the toner may harm health if scattered (environmental destruction = pollution). Therefore, in the case of the pulverized toner, it is desirable to remove the crushed fine particles of about 1 to 2 μm as much as possible.
[0082]
When the development is completed, a voltage having a polarity opposite to the charge held by the toner (a positive voltage with respect to the negatively charged toner) is applied by using the transfer device (5), and the toner image is formed on the copy paper (9). Is transcribed.
After the transfer is completed, the copy paper is separated from the photoreceptor (1) by a separating device (6) to which an AC voltage or a DC voltage on which the AC voltage is superimposed is applied, and is sent to a fixing device (8). Become a copy. The separation device (6) is generally a corona discharge device that applies an AC voltage or an AC voltage obtained by superimposing a DC voltage to a metal wire or a sawtooth electrode. The electric field intensity applied to the photoreceptor via the copy paper may be such that the copy paper is separated from the photoreceptor, so that the amount of corona products generated is small and may be non-uniform, causing photoreceptor damage. Not as much. When the diameter of the photoreceptor is 30 mm or less, the separating device may be omitted in some cases due to the paper stiffness.
[0083]
On the other hand, the residual toner on the photoreceptor after separation of the copy paper is mainly a cleaning brush (7-1) made of fiber such as polyethylene, nylon, or carbon fiber, or polyurethane rubber, but silicone rubber or neoprene rubber. Cleaning is performed by a cleaning device (7) including a cleaning blade (7-2) made of a material such as fluorine rubber.
[0084]
Here, a series of copying processes is completed, but when the lubricant is applied to the photoconductor (1), the lubricant is applied to the photoconductor (1) by, for example, the means of FIG. A lubricant is applied to the cleaned photoreceptor (1) by a lubricant applying device (200) shown in FIG. The lubricant applying device (200) in FIG. 2 is a system in which a lubricant such as zinc stearate or polytetrafluoroethylene is indirectly applied to the photoreceptor via a dedicated application brush (202). A method for applying a lubricant to the photoreceptor (1) by causing the lubricant (201) to act on the cleaning brush (7-1) is another method for applying the lubricant (201) to the photoreceptor (1). A lubricant such as zinc stearate, polytetrafluoroethylene, or polyvinylidene fluoride having a particle size of about 0.01 to 0.5 μm in a developer in a range where the characteristics of the toner are not changed (0.01 to 0.5 μm). -0.5% by weight). When added to the surface of the photoreceptor, there is no need to provide a lubricant.
[0085]
The copying process described with reference to FIGS. 1 and 2 can be applied to a full-color image forming apparatus. Although not shown, in a full-color electrophotographic copying machine or a color laser beam printer, one photoconductor has four systems (colors) of yellow (Y), magenta (M), cyan (C), and black (Bk). ), A one-drum type image forming apparatus provided with a developing device, as shown in FIG. 3, four photoconductors and four photoconductors of yellow (Y), magenta (M), cyan (C), and black (Bk) There is an image forming apparatus of a four-tandem tandem type using a system (color) developing device.
The photoreceptor, the charging device, the developing device, and the cleaning device including the cleaning brush and the cleaning brush shown in FIGS. 1 and 2 can be detachably attached to the image forming apparatus main body by combining two or more of them. And a simple process cartridge.
For example, 1) a photoconductor and a charging device, 2) a photoconductor, a cleaning device, a lubricant application device, and the like are examples thereof.
[0086]
Next, the photoconductor will be described.
2. Photoconductor
2-1 Photoconductor outline
FIG. 4 shows the basic configuration of the photoconductor. The organic photoreceptor is a photoreceptor formed on a drum-shaped aluminum conductive support in this order of an undercoat layer, a charge generation layer, and a charge transport layer. The charge transport layer uses at least an organic material.
In the present invention, as shown in FIG. 5, the charge transport layer further includes a filler non-dispersed charge transport layer (normal charge transport layer) and a filler dispersed charge transport layer in which an inorganic filler is dispersed.
The charge transport layer composed of the non-filler-dispersed charge transport layer and the filler-dispersed charge transport layer is a layer in which a low-molecular charge transport material is dispersed with an appropriate amount of a binder resin, an antioxidant, a dispersant, etc., or a polymer. The film thickness and the layer structure can be set according to the required quality of the photoreceptor.
[0087]
The first purpose of adding a filler (in the present invention, an inorganic filler composed of alumina (α-type) is particularly preferably used) is to increase the hardness of the surface layer of the photoreceptor by adding an appropriate amount of the filler. By increasing the abrasion, the life of the photoreceptor is extended and the image quality is stabilized. However, a significant increase in hardness may cause image deterioration such as image deletion in order to reduce wear of the photosensitive layer.
The second purpose is to disperse a small particle size filler on the surface of the photosensitive layer to set a suitable hardness, to suppress a large increase in the coefficient of friction, and to suppress the cleaning blade edge from penetrating into the layer. Thus, it is to reduce the distortion and deformation of the blade edge.
[0088]
The amount of the filler added to the charge transport layer depends on the initial and temporal resolution, the uniformity of the dot pattern, the hardness, and the surface roughness (10-point average roughness Rz). _JIS , The maximum height Rz, etc.). When a contact charging method or a non-contact charging method is used, a filler having an average particle size of 0.3 to 0.7 μm is added to the total weight of the charge transport layer to which the filler is added. 20 wt% or more and 35 wt% or less are suitable.
The thickness of the photosensitive layer is desirably set to a value enough to obtain a sufficient contrast image and a thickness that can secure a contrast potential. It is desirable that the contrast potential (difference between the developing bias potential and the image portion potential) for obtaining good image forming properties is at least 250 V or more.
It is preferable that the film thickness for ensuring a contrast potential of 250 V or more is at least, and the total thickness of the photosensitive layer is 10 μm or more. If the film thickness is reduced to 10 μm or less, it is difficult to secure a sufficient charge level, and it is difficult to obtain a sufficient contrast potential. Further, unevenness in the thickness of the photosensitive layer tends to appear in the image, resulting in non-uniform image quality. On the other hand, if the thickness is too large, the dot pattern spreads in the layer, causing a reduction in sharpness and resolution, making it difficult to achieve a high-quality image.
Therefore, the preferable thickness t of the photosensitive layer is 10 μm ≦ t ≦ 30 μm.
[0089]
Hereinafter, the function-separated type organic photoreceptor used in the present invention will be described.
2-2 Conductive support
First, the conductive support will be described.
Materials that can be used as the conductive support (CL) of the photoreceptor include metals such as stainless steel, copper, and brass that satisfy various electrical, mechanical, and chemical properties, as well as compressed paper, resin, and glass. Examples include a conductive layer on which aluminum, platinum, chromium, or the like is deposited or sputtered, and a conductive layer on which fine particles such as carbon or tin are dispersed. Taking into account the fact that thin-wall cutting is easy, light, advantageous for reproduction, easy to form a blocking layer, easy to obtain, and the like, aluminum, particularly an aluminum alloy such as JIS3003 is preferable.
The technologies for processing the surface of aluminum include cutting, honing, and blasting.The drum-shaped aluminum tube is cut to the required length, cut to the target outer diameter, and then super-finished. , Mirror finish, etc., to make the surface roughness 10 points average roughness Rz _JIS And then sufficiently washed until the washing solution is completely removed, and used as a conductive support for an electrophotographic photosensitive member. 10-point average roughness Rz of the support _JIS If the thickness is usually 10 μm or less, an abnormal image due to the surface roughness of the support can be suppressed to a level that does not cause any practical problem.
The shape of the conductive support is desirably a drum shape, and the outer diameter is generally about 30 mm to 100 mm.
The thickness of aluminum is about 0.6 mm to 3 mm for a photoreceptor having an outer diameter of φ30 to φ100 mm, but the temperature at the time of heating and drying is 120 to 160 ° C., and the time is 10 to 60 for an organic photoreceptor. Since it is on the order of minutes, a thinner one is preferable if it is not deformed at such a temperature and time. The advantage of thinning is advantageous in terms of cost, and when a damping member is incorporated, the damping effect is enhanced. However, if it is thin, it may be deformed when the flange is mounted or when the vibration damping member is built in, and the shape and dimensions of these members require sufficient management. In other words, when the charging and the blade contact each other due to the deformation of the outer diameter, a slight shift occurs between the members and the charging roller, which causes uneven charging and affects the cleaning performance.
[0090]
2-3 Undercoat layer
Next, the undercoat layer will be described.
An undercoat layer (UL) is provided between the conductive support and the photosensitive layer, if necessary.
The form of the undercoat layer may vary depending on the wavelength range used for the light source. For example, when used for a light source such as an LD element or an LED array having an oscillation wavelength in a long wavelength region of 650 to 780 nm, moiré occurs due to reflection of light from aluminum. Therefore, an undercoat layer is indispensable. However, when an LD element having an oscillation wavelength of about 400 to 420 nm is used, the absorption near the surface layer increases, so that the undercoat layer as described in the specific example of the present invention is not necessarily required. Or a semiconductor film that blocks hole injection.
[0091]
The reason for forming the undercoat layer is to prevent charge injection from the support side, stabilize charging characteristics, improve adhesion, prevent moiré, improve coatability of the upper layer, reduce residual potential, etc. With the goal. Therefore, a method may be adopted in which a semiconductor film is formed to prevent injection of holes (holes) and allow electrons (electrons) to pass therethrough, and further form an intermediate layer or an undercoat layer thereon. In general, the undercoat layer is formed of a thin film containing a resin as a main component and having a high resistance so that potential decay hardly occurs within a unit time. Considering that the undercoat layer is to be coated with a photosensitive layer using a solvent, it is preferable that the undercoat layer be a resin having high solubility resistance to general organic solvents. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, and epoxy resin. And a curable resin forming a three-dimensional network structure. Further, fine powders of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be dispersed and contained. These undercoat layers can be formed using a suitable solvent and a coating method.
[0092]
Further, as the undercoat layer of the present invention, a metal oxide layer formed by using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like by a sol-gel method or the like is also useful.
In addition, as the undercoat layer of the present invention, Al ₂ O ₃ , An organic substance such as polyparaxylylene (Parylene = trade name of Union Carbide), SnO ₂ , TiO ₂ , CeO ₂ Inorganic substances such as are provided by a vacuum thin film manufacturing method. ¹⁰ -10 ^Thirteen A thin film having an electric resistance on the order of Ω · cm can be used favorably. The thickness of the undercoat layer is suitably from 0.1 to 20 μm, and preferably from 0.5 to 10 μm.
[0093]
2-4 Charge generation layer
Next, the charge generation layer will be described.
The charge generation layer (CGL) is a layer containing a charge generation substance (CGM) as a main component, and a binder resin is used as necessary. As the charge generation substance, there are an inorganic material and an organic material.
Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and amorphous silicon. As amorphous silicon, a material in which a dangling bond is terminated with a hydrogen atom or a halogen atom, or a material in which a dangling bond is doped with a boron atom, a phosphorus atom, or the like is preferably used.
[0094]
On the other hand, as the organic material, a known material can be used. For example, phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine, azulhenium salt pigment, methine squaric acid pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bisstillene skeleton, azo pigments having a distyryl oxadiazol skeleton, azo pigments having a distyryl carbazole skeleton, Perylene pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Njigoido based pigments, and bisbenzimidazole pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.
[0095]
As the binder resin used as necessary for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N- Vinyl carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more. In addition, a low molecular charge transport material may be added as needed.
[0096]
Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trione An electron accepting substance such as nitrodibenzothiophene-5,5-dioxide is exemplified. These electron transport materials can be used alone or as a mixture of two or more.
[0097]
Examples of the hole transport material include the electron donating materials shown below and are preferably used.
For example, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline Phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives and the like. These hole transporting substances can be used alone or as a mixture of two or more.
The charge generation layer contains a charge generation substance, a solvent, and a binder resin as main components, and may include any additives such as a sensitizer, a dispersant, a surfactant, and a silicone oil. good.
[0098]
As a method for forming the charge generation layer, a vacuum thin film preparation method and a casting method from a solution dispersion system are largely mentioned. For the former method, a vacuum evaporation method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-mentioned inorganic material and organic material can be favorably formed. In addition, in order to provide a charge generation layer by a casting method, if necessary, the above-mentioned inorganic or organic charge generation material is used together with a binder resin together with a binder resin such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, or a ball mill, an attritor, or the like. It can be formed by dispersing with a sand mill or the like, diluting the dispersion liquid appropriately and applying. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, and preferably 0.05 to 2 μm. Usually, it is applied to a thickness of 0.1 to 0.3 μm.
If the film thickness is too small, sensitivity is poor, but if it is too thick, light attenuation and residual potential increase due to space charge, resulting in image quality deterioration such as image density reduction and resolution reduction.
[0099]
2-5 Charge transport layer
Next, the charge transport layer (CTL) will be described.
The charge transport layer is formed to secure a surface potential required for image formation. The charge transport layer can of course be used alone with an organic photosensitive layer. However, in order to maintain the durability of the photoreceptor and maintain the image quality, the surface of the organic photosensitive layer (non-filled charge transport layer) should have a higher hardness. To form a filler-dispersed charge transport layer to which an appropriate amount of ultrafine inorganic filler particles is added. In the present invention, as shown in FIG. 5, the charge transport layer is composed of a non-filler-dispersed charge transport layer and a filler-dispersed charge transport layer, and is configured such that no clear interface exists between both charge transport layers. By avoiding the formation of a clear interface, of the holes and electron pairs generated by image exposure, most of the holes that move toward the surface move to the surface without being captured near the interface and become charged. Can be canceled without loss of time.
That is, since the optical attenuation characteristic hardly deteriorates, high-definition image quality can be reproduced.
However, since the filler is dispersed, a slight loss due to the amount of dispersion of the filler, the particle size, etc., for example, light diffusion, variation in charge distribution occurs, but when added in a suitable range, it can be ignored. And there is no practical problem.
[0100]
When an interface is formed between the two charge transport layers, the movement of holes is restricted, so that the light attenuation characteristic is degraded and the residual potential is increased, so that the contrast potential is reduced and the afterimage is easily caused.
The coating means for preventing the formation of the interface can be prepared by a spray coating method when the thickness of the charge transport layer is as thin as about 10 μm. Inject the liquid and the filler-dispersed charge transport layer liquid in the other, apply the filler non-dispersed charge transport layer on the charge generation layer first, wait for a touch drying time (several minutes), and then continue the filler dispersion. What is necessary is just to apply a charge transport layer. When the charge transport layer is as thick as 25 μm or 30 μm, and when the filler non-dispersed charge transport layer is as thick as 20 μm, first, the filler non-dispersed charge transport layer is formed, touch dried, and further dried by heating at 120 to 130 ° C. Thereafter, a filler-dispersed charge transporting layer is formed within a relatively short time, and the entire photoreceptor is heated and dried at a temperature of 130 to 160 ° C. for about 10 to 60 minutes to prepare a photoreceptor.
[0101]
The charge transporting layer (filler non-dispersed charge transporting layer + filler dispersed charge transporting layer) is required after dissolving or dispersing a mixture or copolymer mainly composed of a charge transporting component and a binder component in an appropriate solvent. It can be formed by coating to a desired thickness and drying.
The thickness of the charge transport layer is set to 10 to 30 μm. However, the smaller the variation (the difference between the maximum thickness and the minimum thickness) of the entire photosensitive layer is, the more easily the influence of coating unevenness occurs. Desirably, the distance is set within a range of ± 1 μm for 10 μm and ± 2 μm for 30 μm.
The smaller the thickness of the charge transport layer, the greater the capacitance, and thus the higher the electric field strength, but it is difficult to secure a high charge level. If the charge of the toner is small, the developing ability can be increased even with a photoreceptor with a small film thickness, but voltage development is inevitable for toners of small particle diameter currently used in the market at present. Therefore, a certain or more surface potential is required.
[0102]
When the thickness of the photosensitive layer is reduced, the distortion of the charge transfer is reduced, so that a high-quality image can be reproduced. On the other hand, as the thickness increases, the capacitance decreases, so that a high charge level can be secured. However, when the charge moves, the charge tends to be distorted upon input of light, and the resolution tends to decrease. When the thickness of the photosensitive layer is set to about 10 μm, the charged portion is charged only at about −450 V at most. However, if the residual potential is suppressed to about −50 V to −100 V and the developing bias potential is set to −350 V, the contrast potential can be secured to about 250 V to 300 V, and it is possible to perform an image without practical problems. .
[0103]
The charge transport layer is formed on the charge generation layer in the order of the filler non-dispersed charge transport layer and the filler dispersed charge transport layer. This is because, when the filler-dispersed charge transport layer is in direct contact with the charge generation layer, abnormal movement of charges occurs between the filler-dispersed charge transport layer and the charge generation layer, so that a speckle pattern appears on the image. Therefore, in the region in contact with the charge generation layer, it is desirable that the charge transport layer does not disperse the filler, and it is desirable that the film thickness be at least 2 μm or more.
For the coating film, a dip coating method, a spray coating method, or the like can be used.
[0104]
The filler added to the filler-dispersed charge transport layer is spherical and has high hardness, has optical transparency, and has an electric resistance of 10%. ¹⁰ It is preferable that the resistance is Ω · cm or more. Preferably 10 ¹² Ω · cm-10 ¹⁴ Ω · cm. If the specific resistance is low, it is difficult to hold the charge, and if the specific resistance is too high, the resolution is lowered.If the specific resistance is too high, the residual potential is increased, the image portion potential is increased, the contrast potential is reduced, and a sufficient image density cannot be obtained. , Resulting in an image with many irregularities.
The filler in the filler-dispersed charge transport layer is preferably uniformly dispersed in the charge transport layer, or a layer configuration in which the concentration gradient is increased toward the surface layer, but from the viewpoint of maintaining durability, Uniform dispersion is more desirable.
The amount of filler dispersed in the charge transport layer depends on the required durability (depending on abrasion, chemical and physical deterioration), and image quality (depending on the aging characteristics such as charge level, sensitivity and residual potential). To 20% by weight to 35% by weight based on the total weight of the filler-dispersed charge transport layer. If it is less than 20% by weight, abrasion increases rapidly, and if it is more than 35% by weight, residual potential increases, photosensitive layer surface roughness deteriorates, and surface roughness increases. As a result, toner loss is likely to occur, leading to formation of toner filming, leading to image deletion.
[0105]
It is necessary to change the setting of the film thickness of the filler-dispersed charge transport layer depending on the durability required for the photoreceptor and the image quality characteristics. From the viewpoint of durability, it is desirable that the filler-dispersed charge transport layer is thicker. However, as the thickness increases, the optical characteristics and electric characteristics deteriorate, so that the resolution and the residual potential increase, and the image quality deteriorates. Therefore, it is necessary to keep the film thickness within a range that can maintain the required image quality. When the amount of the filler added is in the range of 20% by weight or more and 35% by weight or less, an acceptable film thickness is about 8 μm. Normally, when the thickness is set to about 3 to 6 μm, good image quality can be maintained. .
[0106]
The material used for the charge transport layer will be described.
Oxazole derivatives, oxadiazole derivatives, imidal derivatives, triphenylamine derivatives, α-phenylstilbene derivatives, toniphenyl methane derivatives, anthracene derivatives, and the like can be used as the low-molecular-weight charge transport material constituting the charge transport layer.
[0107]
On the other hand, as the polymer charge transporting substance, the following known polymer charge transporting materials can be used. For example,
1) Polymers having a carbazole ring in the main chain and / or side chain include, for example, poly-N-vinylcarbazole, JP-A-50-82056, JP-A-54-9632, There are compounds described in JP-A-54-11737 and JP-A-4-183719.
2) Polymers having a hydrazone structure in the main chain and / or side chain include, for example, compounds described in JP-A-57-78402 and JP-A-3-50555.
3) Examples of the polysilylene polymer include compounds described in JP-A-63-285552, JP-A-5-19497, and JP-A-5-70595.
4) Polymers having a tertiary amine structure in the main chain and / or side chain include, for example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-13061, JP-A-1-19049, JP-A-1-1728, JP-A-1-105260, JP-A-2-167335, JP-A-5-66598, and compound described in JP-A-5-40350 Etc.
5) Other polymers include, for example, formaldehyde polycondensates of nitropyrene and compounds described in JP-A-51-73888 and JP-A-56-150749.
[0108]
The polymer having an electron donating group used in the present invention is not only the above-mentioned polymer, but also a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, and, for example, It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-3-109406.
As the polymer charge transporting material in the present invention, a polycarbonate having a triarylamine structure in the main chain and / or side chain is effectively used.
[0109]
On the other hand, examples of the high molecular compound that can be used as the binder component include polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester resin, polyvinyl chloride, and chloride. Vinyl / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate resin (bisphenol A type, bisphenol C type, bisphenol Z type or a copolymer thereof), cellulose acetate resin, ethyl cellulose resin, polyvinyl Thermoplastic or heat of butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. Including but of resin, but is not limited thereto. These polymer compounds can be used singly or as a mixture of two or more kinds, or copolymerized with a charge transport material.
Examples of dispersion solvents that can be used when preparing the charge transport layer coating liquid include, for example, methyl ethyl ketone, acetone, methyl isobutyl ketone, ketones such as cyclohexanone, dioxane, tetrahydrofuran, ethers such as ethyl cellosolve, toluene, xylene and the like. Examples thereof include aromatics, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate. However, it is desirable to avoid using a halogen-based solvent in consideration of environmental destruction.
[0110]
Next, the filler dispersed in the charge transport layer will be described.
The filler used in the present invention is an oxide insulator, and when dispersed in a binder resin, traps are easily formed at the interface between the particles and the binder resin. Therefore, when the photoreceptor is used repeatedly, the residual potential accumulates and the potential of the image portion is increased, so that the image density and the resolution are easily reduced. Therefore, an additive can be added to improve the dispersibility, uniformize the photosensitive layer, inhibit the formation of traps, or reduce the trap density.
Means for imparting electric charge to the photoreceptor during image formation is performed by a charging device that is in contact with or close to the photoreceptor, and corona products such as ozone and nitrogen oxides generated during charging are applied to the photoreceptor. It attaches to the surface layer or penetrates into the photosensitive layer, lowering the electrical resistance and causing deterioration in image quality such as resolution. In order to solve this, a small amount of an antioxidant and a plasticizer can be added. However, these additives are not always necessary, and may be omitted when the charge transport layer is thin, when the amount of the filler added is small, or depending on the image system.
[0111]
In the charge transporting layer to which the filler is added, a coating liquid in which a suitable amount of the filler is dispersed in a binder resin is applied to a target film thickness by using a coating method such as a spray method or a dipping method.
Filler is 10 ¹⁰ -10 ^Fifteen It is desirable that the material has a specific resistance of about Ω · cm, has water repellency, and maintains its function. Especially 10 ¹² -10 ¹⁴ Ω · cm.
The filler material includes an organic filler material and an inorganic filler material. Examples of the organic filler material include a fluororesin powder such as polytetrafluoroethylene, a silicone resin powder, and an amorphous carbon powder. Materials include metal powders such as copper, tin, aluminum, and indium, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, tin oxide and tin doped with antimony. Metal oxides such as doped indium oxide; metal fluorides such as tin fluoride, calcium fluoride, and aluminum fluoride; and inorganic materials such as potassium titanate and boron nitride. Among these fillers, it is advantageous to use an inorganic material from the viewpoint of the hardness of the filler for improving the wear resistance.
[0112]
In particular, titanium oxide or alumina can be desirably used in the present invention, but alumina (particularly α-type) is more preferable. Alumina has the second highest hardness after diamond, exhibits relatively good light transmission, has good dispersibility in resin, has a strong oxide film, and has a specific resistance of 10%. ^Thirteen -10 ^Fifteen It is around Ω · cm. Furthermore, since it has water repellency, environmental stability is excellent. Therefore, when used as a filler for a photoreceptor, stable photoreceptor characteristics are exhibited even when used for a long time.
[0113]
The filler material can be dispersed together with a charge transport substance, a binder resin, a solvent, and the like using an appropriate disperser.
When the surface roughness of the photosensitive layer is increased by the addition of the filler, the edges of the character become jagged, and the cleaning properties of the residue such as toner and paper powder are deteriorated, resulting in a problem of poor cleaning. Contaminants such as corona products remain in areas where the blades do not contact, causing image bleeding, toner filming and even chipping of the edges of the cleaning blade, making the photosensitive layer more susceptible to damage. Therefore, it is necessary to select a filler having a particle size with good dispersibility so that the target abrasion resistance can be achieved and good image quality can be obtained. The primary particle size of the filler dispersed in the photosensitive layer is determined by the light transmittance, abrasion resistance, surface roughness and the like of the charge transport layer.
[0114]
FIGS. 6 to 8 show measurement examples of the particle diameter and the amount of the filler and the surface roughness of the filler-dispersed charge transport layer formed on the charge transport layer of the photoreceptor. The photosensitive layer has a filler non-dispersed charge transporting layer of 22 μm and a thickness of the filler dispersed charge transporting layer of about 5 μm, and was measured using Surfcom Model 1400D manufactured by Tokyo Seimitsu Co., Ltd.
FIG. 6 shows the filler particle size and the surface roughness (maximum height Rz, 10-point average roughness Rz) of the filler-dispersed charge transport layer (addition amount: 25% by weight) formed on an aluminum support having a diameter of 30 mm. _JIS FIG. 7 also shows the amount of filler (an average particle diameter of 0.3 μm) and the surface roughness (maximum height Rz, 10-point average roughness Rz) of a photoreceptor of φ60 mm. _JIS FIG. 8 shows the amount of filler (an average particle diameter of 0.3 μm) and the surface roughness (maximum height Rz, 10-point average roughness Rz) of a photosensitive member having a diameter of 30 mm. _JIS ).
[0115]
10-point average roughness Rz _JIS The reason for defining the maximum height Rz is as follows.
10-point average roughness Rz _JIS Stipulates that the 10-point average roughness Rz _JIS Is smaller than the minimum toner, it is possible to prevent toner loss. On the other hand, by defining Rz, it is possible to prevent the toner with the minimum toner particle diameter from falling off when no distortion (twist) occurs in the blade.
In other words, in order to prevent toner loss, it is necessary to define both the 10-point average roughness RzJIS and the maximum height Rz.
10 point average roughness Rz _JIS In order to achieve the above, a means for reducing the frictional resistance between the blade and the photoreceptor by a lubricant is indispensable. However, the means for lowering the friction coefficient may be a means for adding a lubricant to the outermost surface layer of the photoreceptor, or a means for replacing the lubricant.
When the filler particle size is 0.5 μm and the added amount exceeds 30% by weight to 40% by weight, the surface roughness tends to suddenly increase (see FIGS. 7 and 8). When the surface roughness is larger than the minimum particle size of the toner, toner detachment is likely to occur, and when the blade is twisted, the toner detachment is further increased.
Further, the sharpness of a character image due to surface contamination of the photoreceptor decreases. Toner loss is determined by the minimum particle size of the toner. When a toner having a weight average particle size of 4 μm is used, the frequency of existence of the toner having the minimum particle size of about 1 μm is about several percent. If the maximum height Rz of the roughness is 1.5 μm or less, the toner can be almost prevented from being removed.
This value is a value that is effective not only in the initial stage but also for the durability of the photoconductor. That is, it is necessary to maintain the value within the above-mentioned value in order to prevent toner loss. In addition, 10-point average roughness Rz _JIS Is important to maintain good image quality.
The 10-point average roughness Rz _JIS The filler particle size and the amount of addition satisfying the maximum height Rz are about 1.1 μm and about 45% by weight, respectively. It is desirable that the average particle diameter of the filler added to the transport layer is 0.3 μm or more and 0.7 μm or less, and the addition amount is 20% by weight or more and 35% by weight or less.
As described above, the filler particle size and the amount added to the charge transport layer not only affect the surface roughness of the photoreceptor surface, but also have a great influence on electrical and mechanical properties. is necessary.
In the contact charging and the non-contact charging method, the photoreceptor suffers large chemical damage, so that the abrasion resistance needs to be increased. As the amount of the filler is smaller, the abrasion resistance is lower. When the amount is 20% by weight or more, the abrasion resistance is gradually improved. is there. Therefore, when using contact charging or non-contact charging, it is desirable to add at least 20% by weight when using alumina at least.
[0116]
As a means for eliminating roughness of the photosensitive layer surface and smoothing it, for example, adding a leveling agent to the charge transport layer according to the invention is an effective means. As the leveling agent, a known material can be used, but a silicone oil-based leveling agent, which can impart a high level of smoothness in a small amount and has a small effect on electrostatic characteristics, is particularly preferable. Examples of silicone oils include dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen polysiloxane, cyclic dimethyl polysiloxane, alkyl-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, and amino-modified silicone oil. Examples include silicone oil, mercapto-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, higher fatty acid-modified silicone oil, and higher fatty acid-containing silicone oil. In addition, it is possible to reduce unevenness depending on conditions at the time of coating and the like. For example, in dip coating, after lifting the photoreceptor, if the coating surface is still wet, cover it with a hood so that the surface is not disturbed by wind flow etc. Is done. Also, if the solvent near the surface of the coating film evaporates rapidly, only the surface is hardened and the inside of the coating film becomes fluid, and the coating film inside this film may sag and form irregularities. In a wet state, a vapor layer of a solvent is formed around the photoreceptor, and the solvent is gently volatilized, whereby leveling progresses, and unevenness is reduced and smoothed.
[0117]
Also, in spray coating, when forming a coating film by air spray, by controlling the air pressure and the air flow rate to an appropriate amount, the surface of the coating film in a fluid state is suppressed and irregularities are suppressed. It is necessary to control. Here, if the air pressure and air flow rate are too large, the surface of the coating film will be disturbed by the flow of air, while if too small, the droplets of the coating liquid will not be uniform or the atomization will be insufficient. As a result, the uniformity of the coating film is reduced. After the charge transport layer is formed, the solvent is volatilized while being rotated. If the rotation speed is too high, centrifugal force is applied to the coating film which still contains the solvent and has fluidity, so that unevenness is emphasized. On the other hand, if the rotation speed is too low, the effect of sagging due to gravity is greater than the leveling due to rotation, which may cause unevenness. Therefore, it is necessary to set the rotation speed of the photoconductor in a wet state of the coating film to an appropriate value.
Further, in spray coating, it is important that the supply of a pump for supplying a coating liquid is constant. In other words, if the supply of the liquid is not constant and has a pulsation, the pulsation directly affects the discharge amount of the liquid, so that the adhesion amount becomes uneven. Therefore, as a pump for supplying the liquid to the spray, it is preferable to use a multiple plunger pump in which pulsation is suppressed, a syringe-type super-precision discharge device, or the like.
These methods may be used alone, but by combining a plurality of them, a more effective leveling is performed and a charge transport layer with reduced unevenness is formed.
Furthermore, when the leveling is insufficient, it is also possible to wear and smooth the convex portions of the charge transport layer as a method of reducing unevenness. For example, a method in which a convex portion is detected by a film thickness meter and the portion is polished to eliminate the convex portion can be considered.
[0118]
In the present invention, in order to improve environmental resistance, and to prevent a decrease in sensitivity and a rise in residual potential, oxidation of each layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, and an intermediate layer is performed. Inhibitors, plasticizers, lubricants, UV absorbers, and low molecular charge transport materials can be added. Representative materials of these compounds are described below.
[0119]
Examples of the antioxidant that can be added to each layer include the following, but are not limited thereto.
(A) Phenolic compound
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5 '-Di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-t-butylphenol) 4,4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), 1,1,3-tris- ( 2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, Tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid] Crychol esters, tocopherols and the like.
(B) paraphenylenediamines
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-tert-butyl-p-phenylenediamine and the like.
(C) Hydroquinones
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl ) -5-methylhydroquinone and the like.
(D) Organic sulfur compounds
Dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like. (E) Organic phosphorus compounds
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.
[0120]
Examples of the plasticizer that can be added to each layer include the following, but are not limited thereto.
(A) Phosphate ester plasticizer
Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate and the like.
(B) Phthalate ester plasticizer
Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, dinonyl phthalate, dinononyl phthalate, phthalic acid Diisodecyl, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate and the like.
(C) Aromatic carboxylate plasticizer
Trioctyl trimellitate, tri-n-octyl trimellitate, octyl oxybenzoate and the like.
(D) Aliphatic dibasic ester plasticizer
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl adipate-n-decyl, diisodecyl adipate, dicapry adipate, diazellate -2-ethylhexyl, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, Dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like. (E) Fatty acid ester derivatives
Butyl oleate, glycerin monooleate, methyl acetyl ricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
(F) Oxyacid ester plasticizer
Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.
(G) Epoxy plasticizer
Epoxidized soybean oil, epoxidized linseed oil, butyl epoxystearate, decyl epoxystearate, octyl epoxystearate, benzyl epoxystearate, dioctyl epoxyhexahydrophthalate, didecyl epoxyhexahydrophthalate, and the like.
(H) Dihydric alcohol ester plasticizer
Diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate and the like.
(I) Chlorine-containing plasticizer
Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxy chlorinated fatty acid methyl and the like.
(J) Polyester plasticizer
Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, etc.
(K) sulfonic acid derivative
P-toluenesulfonamide, O-toluenesulfonamide, P-toluenesulfonethylamide, O-toluenesulfonethylamide, toluenesulfone-N-ethylamide, P-toluenesulfon-N-cyclohexylamide and the like.
(L) Citric acid derivative
Triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, acetyl tri-2-ethylhexyl acetyl citrate, n-octyldecyl acetyl citrate and the like.
(M) Other
Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.
[0121]
In the present invention, a lubricant can be added to each layer. Examples include, but are not limited to, the following.
(A) Hydrocarbon compounds
Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, etc.
(B) fatty acid compound
Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, etc.
(C) Fatty acid amide compound
Stearyl amide, palmityl amide, olein amide, methylene bis stearoamide, ethylene bis stearoamide and the like.
(D) Ester compound
Lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acid polyglycol esters.
(E) Alcohol compounds
Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
(F) Metal soap
Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
(G) Natural wax
Carnauba wax, Candelilla wax, beeswax, whale wax, Ibota wax, Montan wax, etc.
(H) Other
Silicone compounds, fluorine compounds, etc.
[0122]
Examples of the ultraviolet absorber that can be added to each layer include the following, but are not limited thereto.
(A) Benzophenone type
2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone and the like.
(B) salicylate
Phenyl salicylate, 2,4-di-t-butylphenyl 3,5-di-t-butyl-4-hydroxybenzoate and the like.
(C) Benzotriazole type
(2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy-3′-tert-butyl) -5'-methylphenyl) -5-chlorobenzotriazole
(D) cyanoacrylate-based
Ethyl-2-cyano-3,3-diphenyl acrylate, methyl-2-carbomethoxy-3- (paramethoxy) acrylate and the like.
(E) Quencher (metal complex salt)
Nickel (2,2′-thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyl dithiocarbamate, nickel dibutyl dithiocarbamate, cobalt dicyclohexyl dithiophosphate, and the like.
(F) HALS (Hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- 2,2,6,6-tetramethylpiperidine and the like.
There is.
[0123]
3. Cleaning member (cleaning brush and cleaning blade)
In the present invention, the cleaning device (7) includes a cleaning brush (7-1) and a cleaning blade (7-2) as shown in FIGS. 1, 2, 11, and 12. The cleaning brush is installed so as to make uniform surface contact (contact) with the photoconductor. The bite amount into the photoconductor is preferably 1 to 2 mm. Non-uniform installation causes uneven wear not only on the photosensitive layer but also on the brush. The rotation direction may be either the counter direction or the reading direction, but is preferably the reading direction (the direction opposite to the rotation direction of the photoconductor). This is because, in the counter direction, the photosensitive layer is easily shaved and uneven shaving is likely to occur. Further, the present invention is characterized in that a flicker bar, which is generally provided, is not provided in order to remove toner attached to the brush. This is because, when the flicker bar is provided, in the case of the loop brush, the toner is likely to be unevenly removed, the toner is easily pushed into the interior of the fiber, and the fiber is easily damaged. That is, the shaving of the photosensitive layer is apt to cause unevenness, the shaving of the filming film is apt to be uneven, and furthermore, the image is sometimes removed in the area of the unevenness in removing the foreign matter.
[0124]
There are mainly two types of brush shapes used for the cleaning brush, a straight hair shape and a loop shape. The loop shape has better cleaning properties and durability, and the present invention uses a loop brush.
The material of the loop brush used for cleaning includes nylon fiber, acrylic fiber, polyester fiber, carbon fiber, and the like, and fiber manufacturers include Unitika, Toray, Kanebo, Kuraray, and Mitsubishi Rayon.
The fiber diameter of the fiber used for the cleaning brush is 10 to 20 (denier = D = weight of thread (g) × 9000９length of thread (m)), density is 24 to 48 filaments / 450 loops, The length (fiber length) is 2 to 5 mm.
[0125]
FIG. 9 is a conceptual diagram showing a state in which a plurality of fibers are looped and woven into the warp and weft fibers of the base cloth. FIG. 10 shows a schematic view of the loop brush roller. As the cleaning brush, a loop brush cut in a strip shape (string shape) is spirally wound around a core metal without any gap, and fixed so as not to be displaced. As a fixing means, an adhesive may be used, or a double-sided adhesive tape may be used. By adopting such a manufacturing method, it is possible to maintain stable, uniform cleaning performance without deviation. The above manufacturing method is simple and can be performed in a short time. If a double-sided adhesive tape is used, the core metal can be reused.
[0126]
The purpose of using a loop brush is to make it less likely to cause abrasion on the photoreceptor as compared with a normal straight-hair cut pile brush. In general, a photosensitive member having a low hardness is rubbed with a cleaning blade, a brush, or a developer, so that the surface of the photosensitive member is more or less rubbed, but when a cut pile brush is used, it is about 100 to 250 rpm. The cut surface of the fiber tip that rotates at the number of rotations hits the photoreceptor, so scratches (small scratches) are more likely to occur than with a loop brush, and in the long term, abnormal images (white spots, black spots) are more likely to occur. Reduce life. In the case of a loop brush, since the rubbing is performed at the antinode or back of the fiber, a deep scratch is rarely generated, and a shallow and uniform rubbing scratch is almost always generated.
The loop brush that can be preferably used in the present invention includes, as acrylic fibers, SA-7 (Toray), nylon-based beltrons ([nylon-based fibers, Kanebo, types 931 and 961, etc.]), polyester-based beltrons [polyester-based] Fiber, Kanebo, type B31, etc.]).
[0127]
When the brush is rubbed with the photoreceptor, triboelectric charging occurs, toner easily adheres to the brush, and a phenomenon that the cleaning property gradually decreases is observed. Therefore, it is desirable that the brush is resistance-controlled. Conductive treatment is carried out at the stage of fiber production, a method of filling conductive carbon into fibers, when the resin is in a molten state, conductive carbon or tin, gold, titanium, etc. You. After the fibers are formed, the conductive fibers and the fibers may be mixed and woven.
However, if the resistance is too low, there is a discharge from the photoconductor, which causes an abnormal image. ⁵ -10 ¹⁰ It is desirable for the resistance to be medium to high about Ω · cm. Both SA-7 and Bertlon are provided with conductivity and have a self-discharge ability even when charged, so even if toner is electrostatically attracted, it can be removed from the brush after copying is completed. it can. In the case of Beltron, conductive fine particles such as carbon are incorporated inside, and in SA-7, carbon is dispersed. It can be seen that Bertron has a higher static elimination ability than SA-7. However, it takes several seconds to several tens of seconds to sufficiently discharge the electric charge.
When the cleaning brush is used, the brush and a core material (metal or resin subjected to conductive treatment) are electrically coupled, and the core material is grounded (grounded) or a voltage is applied to the housing. Usually, it is sufficient to ground.
[0128]
In the case of a hard film such as filming, it is impossible to completely remove even a straight hair brush (cut pile brush), and the removal ability is low with a loop brush. As the amount of filler added to the photosensitive layer increases and the surface roughness tends to increase, the polishing ability of the photosensitive layer by a cleaning device or the like decreases. Therefore, filming is more likely to occur, and the image quality deteriorates.
In order to reliably prevent the filming film from being formed on the photosensitive layer, it is necessary to polish the film before reaching a continuous film on the photosensitive layer. As this means, by coating the cleaning brush with a resin and adding polishing ability, filming buds formed on the surface of the photoreceptor are reliably picked up (polished) every cycle without being worn deeply. This is very important.
The average abrasion amount t for polishing the photosensitive layer with a cleaning brush is 0.1 ≦ t ≦ 0.5 μm per 10,000 sheets (a value converted to a φ30 mm photoreceptor, in the case of A4 size paper), and the abrasion amount is 0.1 μm or less. If the number is too small, there is a high probability that image deletion occurs locally due to uneven polishing, and there is a possibility that an abnormal image is generated due to sticking of titanium oxide or silica in the toner.
On the other hand, when the thickness is 0.5 μm or more, there is no problem in image quality, but durability is not maintained due to large abrasion, and when mass copying is performed, early replacement is inevitable.
Needless to say, as long as the image quality can be maintained, it is desirable that the wear is small.
[0129]
The means for polishing the photosensitive layer is also described in the disclosed examples, but a method using an abrasive or the like causes abrasion and is not practical. The polishing means can be more reliably performed with a brush than with a blade. In order to add a polishing means to the brush, it is necessary to perform a treatment for increasing the polishing strength on the outer wall of the fiber.
In order to surely and uniformly polish filming with an extremely thin film by a simple method, it is preferable to coat the loop fiber with a resin having a high polishing effect. It is necessary to use a material that does not easily wear, does not transfer to the photoreceptor, and does not chemically affect the photoreceptor.
For example, a metal such as tungsten, tin, and aluminum, an amorphous carbon film, silicon, and the like are coated by a method of coating with an acrylic, epoxy, or urethane-based resin, a CVD method, a vacuum evaporation method, a sputtering method, or the like. There are methods.
In the present invention, two liquids of an aqueous urethane adhesive having a viscosity of 5 to 500 (mPa · S) (for example, Mersi 585 manufactured by Toyo Polymer Co., Ltd.) and an epoxy-based curing agent (for example, AD-C-65 manufactured by the company) are used as the main components. A mold can be suitably used. The coating method may be such that the loop brush is laid down sideways, the fiber is immersed in the resin liquid by 2 to 3 mm, the liquid reaches the inside of the fiber, and heat drying is performed. In the case of the above resin, since a liquid such as ion-exchanged water or distilled water is used as a solvent, there is no concern about pollution.
[0130]
On the other hand, a polyurethane blade having a plate thickness of 1.5 to 3 mm, a JIS hardness of 75 to 90 degrees, and a rebound resilience of about 30% to 60% is cut into strips (or sheets) on the cleaning blade. An aluminum or iron support base fixed with an adhesive (FIGS. 11 and 13), a knife edge shape (FIG. 12, FIG. 14) can be used. The blade is a means for completely removing the residual powder (toner, paper powder, corona product, filler, dust, etc.) that could not be removed by the cleaning brush, so the blade is not affected by the surface condition on the photosensitive layer. Need to be cleaned.
The blade is installed in the counter direction with respect to the photoreceptor, and is pressed (contact pressure) so that the bite amount is about 0.5 to 2 mm, and is applied to the tangent line as shown in FIG. 13 (using a strip-shaped blade). It is fixed so that it becomes an acute angle. The contact angle θ2 in FIG. 13 is 15 to 40 degrees, and the free length L2 of the blade tip is 3 to 8 mm.
If the frictional resistance between the photoreceptor and the blade is large, the edge portion contacting the photoreceptor is dragged in the rotation direction of the photoreceptor and locally twisted, and the edge tends to change from line contact to surface contact.
For this reason, a slight gap is generated between the photoconductor and the blade, and the toner is pinched between the blade and the photoconductor, and toner is removed. In order to prevent this, it is necessary to reduce the friction coefficient of the photosensitive layer surface by a suitable means.
[0131]
The shape of the tip of the blade can maintain good cleaning performance by reducing the friction coefficient of the photoreceptor to about 0.3 even with a sheet cut into a strip shape at 90 degrees as described above. Even in the case of a high value of 0.5 or more, it is effective to make the blade tip portion into a knife edge shape as shown in FIG. 14 in order to perform good cleaning performance.
In the case of a knife edge shape, the rubber hardness used for the blade is desirably high, and a rubber blade of about 80 to 90 degrees is used. If the hardness is large, the photosensitive layer is easily worn, but the durability of the photosensitive layer is not reduced by increasing the hardness of the photosensitive member surface with which the blade contacts with the filler. The angle θ1 at the tip of the knife edge in FIG. 14 may be 90 degrees or less, and may be in the range of 30 degrees, and is preferably 60 degrees to 30 degrees. The free length L1 is 2 to 8 mm, preferably 3 to 6 mm.
As means for fixing these cleaning blades (7-2), metals such as aluminum, phosphor bronze, iron and brass, resins such as polycarbonate, vinyl chloride, delrin and polyethylene terephthalate, and ceramic members such as alumina are used for plates and casings. It can be processed and a cleaning blade can be attached, but from the viewpoint of workability, toughness, no temperature deformation, rust, etc., a metal plate with a thickness of about 1 mm to 3 mm like a chromium-plated iron plate or aluminum plate It is suitable. The means for processing the support base and attaching the blade is a method of fitting and fixing the support base in a casing shape, bending a metal plate, and applying an adhesive (double-sided tape, one-part or two-part adhesive, hot melt (For example, an adhesive).
[0132]
In the method for processing a knife-edge-shaped blade shown in FIG. 14, the tip is cut with a knife or is formed by die molding. Polyurethane rubber is mainly composed of a polyol, an isocyanate, and a curing agent. A dehydrating polyol and an isocyanate are mixed, a curing agent is added to a prepolymer obtained by reacting at a temperature of 70 to 140 (° C.) for about 100 minutes, and a molding machine heated to 140 to 160 ° C. in advance. And cure for 50-60 minutes. Then, it is obtained by taking out from a metal mold | die and cutting with a cutting machine to required size.
The polyurethane rubber used for the cleaning blade is cut obliquely with a cutting machine or cut into a knife edge with a mold, and then the burrs on the edge that comes in contact with the photoreceptor are accurately cut straight and the thickness of the tip is reduced. Is adjusted to 0.5 mm or less.
In a mold manufacturing method using this mold, the manufacture can be made relatively easily as long as the mold is made.
[0133]
The contact pressure (linear pressure) when the edge of the blade contacts the photoconductor is preferably set to 15 g / cm to 40 g / cm, but in consideration of the cleaning property, the scratch applied to the photoconductor, and the like, 15 g / cm. It is preferably set to not less than 25 cm / cm and not more than 25 g / cm. At 15 g / cm or less, when a blade having a high JIS-A hardness is used as a blade, a gap is generated between the cleaning blade and the photoconductor even if there is a small amount of foreign matter depending on the surface roughness of the photoconductor, resulting in poor cleaning. Can happen.
When the setting is higher than 25 g / cm, the photoreceptor may be scratched by the blade because the hardness is higher than that of the conventional product. However, even if the setting is higher than 40 g / cm, the scratch occurs. The increased likelihood does not necessarily mean that a shallow abrasion will usually occur, but that the photoreceptor will not be immediately usable except in the case where a hard foreign matter is stuck and the blade edge is damaged.
When the cleaning blade in such a state is used, it is possible to perform satisfactory cleaning even with a spherical toner having an average circularity of 0.95 or more, particularly 0.98 or more.
[0134]
4. Charging member
The charging means for forming an image on the photoreceptor includes a corona charging method, a contact charging method, and a non-contact charging method in which the photoreceptor is charged while holding a gap of 30 μm or more and 100 μm or less. Can use any charging method. However, since the corona charging method generates a large amount of ozone, it is necessary to sufficiently perform ozone exhaust treatment. If leakage occurs, there is a problem of not only odor but also health. A contact or non-contact charging method is preferably used.
Both the contact and non-contact charging methods are charging methods involving discharge, but because the applied voltage is low, the generation of ozone is as low as about 0.1 ppm, and even if there is leakage outside the machine, it is decomposed on the way. There is no odor leaked out. However, since contact charging is a discharge in the vicinity of the photoconductor, chemical damage to the photoconductor may be larger than that of the corona charging method. For this reason, it also affects the abrasion of the photosensitive layer, and the abrasion tends to increase as compared with the corona charging method. Therefore, measures for the wear resistance of the photoconductor are indispensable.
The shape of the charging member can be roughly classified into three shapes: a roller, a brush, and a blade. In consideration of durability, uniform charging, image quality, workability, and the like, a roller charging system as illustrated in FIG. 15 is preferable. .
[0135]
The difference between the contact charging method and the non-contact charging method is that the contact charging method has a gap between the photoreceptor of 0 μm, and the non-contact charging method has a gap of 30 μm or more and 100 μm or less. There are also differences in the resistance values of the members. The gap of 30 μm or more and 100 μm or less is preferably 50 μm or more and 80 μm or less. When the gap is 30 μm or more, even if the roundness or straightness of the photoconductor and the charging member is 20 μm, which is a limit for causing charging unevenness, the photoconductor and the toner do not contact the toner or paper of 10 μm or less. To some extent, contamination caused by powder adhesion can be avoided. In the range of 50 μm or more and 80 μm or less, the average carrier of the developer is 30 to 60 μm. Therefore, when one carrier adheres to the photoreceptor, even if the carrier is pressed against the photoreceptor by the charging roller, the photosensitive layer Means the minimum gap that does not lead to discharge breakdown. Further, as the gap becomes larger, the charging uniformity is more likely to be lost. Therefore, the applied voltage and the frequency must be increased. Therefore, it is necessary to suppress the upper limit of the gap. However, the gap of 80 μm is the minimum gap in which uniform charging can be achieved by slightly increasing the electric field condition applied to the charging member.
[0136]
In the contact charging method, the hardness of the member is mainly about 30 to 80 degrees in JIS-A hardness, but in the case of the non-contact charging member, the JIS-A hardness is about 90 degrees or higher. It can be used up to members. That is, in the case of a non-contact charging member, the surface facing the photoreceptor is formed of a rubber-like or dense sponge elastic resistor having a thickness of 0.5 to 5 mm, and the other regions are formed of metal. It is also possible.
[0137]
The resistance value differs between the contact charging method and the non-contact charging method, and the members used for the contact charging method are set to have higher resistance values. This is because the distance from the photoreceptor is 0 μm, so that charging can be sufficiently performed even if the resistance value is high. Coverage of the area can be reduced.
Specifically, in the case of a contact charging member, the volume resistance is 10 ¹² -10 ¹⁴ Ω · cm, a high-resistance layer with a thickness of about 1 to 3 mm, with flexibility between the core metal and the high-resistance layer to gain a nip 10 ⁵ -10 ⁹ It is composed of a medium resistance layer of Ω · cm. The hardness of the medium resistance layer is about 30 to 75 degrees in JIS-A hardness, and that of the high resistance layer is about 60 to 80 degrees.
On the other hand, in the case of a non-contact charging member, a resistance layer 10 ⁵ -10 ⁸ Use a medium resistance elastic member of Ω · cm. The thickness may be a member of all layers other than the core metal, a medium resistance layer, or a member having a different hardness and resistance value such as a contact charging member. The thickness of the medium resistance layer may be about 1 to 3 mm, and the other may be metal. A charging member having a JIS hardness of 30 to 90 degrees can be used, but a member having a hardness of 60 to 85 degrees is normally used.
[0138]
The elastic material of the resistance layer is a rubber product such as urethane rubber, hydrin rubber, chloroprene rubber, silicone rubber, or fluoro rubber, and resistance control of conductive carbon, activated carbon fiber, metal powders such as tin, gold, and titanium, and ionic conductive agents. This is carried out by adding an appropriate amount of an agent. In the present invention, hydrin rubber is used. The reason is that the hydrin rubber can provide a medium resistance without adding carbon or the like, and the electric resistance is hardly affected by the environment because carbon is not added. However, in order to further reduce the resistance, it may be necessary to add conductive carbon or the like. In the case of a contact charging member, as a protective layer on the outermost layer, a fluororesin and silica are added to hydrin rubber in order to make it difficult for toner and the like to adhere thereto, thereby improving the releasability and increasing the electric resistance to 100 VDC. When applying, 10 ¹² -10 ¹⁴ Set to be within Ω · cm.
[0139]
The surface roughness of the charging member is finer for a member of the contact charging method and rougher for a non-contact charging member. This is to ensure good chargeability, and the 10-point average roughness Rz _JIS The thickness is set to 100 μm to 10 μm for a contact charging member, and to 200 to 20 μm for a non-contact charging member.
In the case of the contact charging method, since the distance from the photosensitive member is 0 μm, even if the resistance of the charging member is increased, the applied voltage can be set lower because the charging efficiency is high as compared with the non-contact charging method. For this reason, the generation amount of ozone and NOx is reduced, and in terms of image quality, even if there is a pinhole, the abnormal image is unlikely to reach other parts. Therefore, it is possible to perform high-quality image formation.
On the other hand, in the case of the non-contact charging method, since there is a distance of several tens of μm, the applied voltage is high. Therefore, the generation of ozone is about three times that of the contact charging method, that is, 0.2 to 0.4 ppm. Since there is almost no leakage to the outside, there is no environmental impact. Since there is a distance from the charging member, the influence on the foreign matter is reduced as compared with the contact charging method. This is advantageous in terms of discharge destruction and contamination of the charging member. However, in the case of a hard foreign substance such as a metal or a high electric field strength, the same precautionary measures as in the rapid charging method are required. The image quality is equivalent to the contact charging method.
[0140]
5. Coefficient of friction of photoreceptor and reduction method
Maintaining the friction coefficient of the photosensitive layer surface at a low level is effective for improving the wear resistance of the photosensitive layer, improving the transferability of a visualized toner image, and improving the cleaning property with a cleaning blade. That is, an effect of reducing the sliding friction pressure of the cleaning blade against the photoconductor and relaxing the adhesion of the toner to the photoconductor is provided. Therefore, the surface layer of the photoreceptor is less likely to be damaged, and when the cleaning blade sufficiently blocks toner, carrier and the like, the cleaning blade becomes only abrasion, and the application of a lubricant can reduce the abrasion. it can.
[0141]
As a means for reducing the friction coefficient, an external addition method of applying a lubricant to the surface layer of the photoreceptor (an example of applying a lubricant scraped off with a brush to the photoreceptor is shown in FIG. 2); The method is carried out by any one of internal addition methods in which a lubricant is contained.
In the internal addition method, a lubricant is added to the surface layer of the photoreceptor by several percent to several tens percent to lower the friction coefficient of the surface. When the addition amount is small (for example, about 5% of polytetrafluoroethylene is added), the corona product acts on the surface layer of the photoreceptor and sometimes blocks the action of the lubricant, so that it is difficult to maintain the friction coefficient. However, when it is added in a large amount (for example, about 50% addition), it can be reduced to about 0.2 to 0.3, and the stable maintenance of the friction coefficient is relatively good. However, the maintenance of the coefficient of friction is carried out by scraping the photosensitive layer, so it is difficult to increase the durability to 100,000 sheets or 200,000 sheets in the case of adding a large amount, but it is an effective means in that no additional equipment is required. This is an advantageous means when high durability is not required.
[0142]
In the case of the external addition method, since it can be supplied from the outside at all times, it is an effective means for maintaining high durability of the photoreceptor. In the external addition method, a substance having lubricity, such as polytetrafluoroethylene, polyvinylidene fluoride, or zinc stearate, can be applied to the surface of the photoreceptor by direct or indirect means.
As a direct method, a means of applying a powdery lubricant by incorporating it into a bag such as a coarse-textured gauze ground, or by rubbing a sheet-like lubricant on the surface of the photoreceptor, an indirect method And a method in which a lubricant is applied by dispersing the toner in a toner by 0.01 to 0.5%, a method in which a lubricant is brought into contact with a cleaning brush, and a powder of the lubricant scraped off by the brush is applied to the photoreceptor. is there.
[0143]
When a lubricant is applied to the photoreceptor, the coefficient of friction of 0.6 can be easily reduced to 0.2 or less with polytetrafluoroethylene. However, in general, if the coefficient of friction is too low, the corona product attached to the photoreceptor will not be scraped off, causing image deletion or causing toner to adhere to the film of the corona product. As a result, toner filming is likely to occur, which may lead to image deletion. In the case of the present invention, however, since the corona product is removed by the cleaning brush, even if the toner concentration is reduced to about 0.2, image deletion occurs. Never. However, if the friction coefficient is too low, the development is affected, and there is a phenomenon in which the character becomes thin due to the slip of the toner. Therefore, it is preferable that the friction coefficient is 0.2 or more, and the friction coefficient is 0.45 or more. It is desirable not to rise. This is because it affects the durability of the photoconductor and the twist of the cleaning blade.
[0144]
The friction coefficient described in the text is calculated using the Euler belt method (an equation calculated based on Euler's formula).
A photoreceptor for measurement was fixed to a pedestal, and high-quality paper (manufactured by Ricoh Co., Ltd., type 6200 paper, using vertical meshes) cut to 30 mm in width and 290 mm in length was prepared as a belt, and the high-quality paper was exposed to light. Attach a 100 gr weight to one end of the belt, attach a digital force gauge for weight measurement to the other end, slowly pull the digital force gauge, The weight is read, and the (static) coefficient of friction (μs) is calculated from the following equation.
[0145]
(Equation 1)
μs = 2 / π × ln (F / W)
Here, μs: static friction coefficient, F: reading load, W: weight of weight, π: pi.
This measurement method (Euler-belt method) is also described in Patent Document 26.
[0146]
[Patent Document 26]
JP-A-9-166919
[0147]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
<Electrophotographic photoreceptor for evaluation>
1) Preparation of a photoconductor having a three-layer structure having a filler non-dispersed charge transport layer
A three-layer photoconductor having a filler non-dispersed charge transport layer used for evaluation was prepared by the following means.
A JIS3003 aluminum alloy drum processed to a diameter of 30 mm, a length of 340 mm, and a thickness of 0.750 mm was used as a conductive support, and was dipped with a coating liquid for an undercoat layer (UL) having the following composition and then heated at 120 ° C. 20 After drying with a 3.5 μm undercoat layer, and then coating with a coating solution for a charge generation layer (CGL) using the charge generation material described in the following [Chemical Formula 1], it was dried by heating at 120 ° C. for 20 minutes. Thus, a 0.2 μm charge generation layer was formed. Further, a charge transport layer (CTL) using the charge transport material described in the following [Chemical Formula 2] was applied by dip coating, and the lifting speed conditions were changed to coat a filler non-dispersed charge transport layer. Thereafter, the resultant was dried by heating at 130 ° C. for 20 minutes to produce an organic photoreceptor having a filler non-dispersed charge transport layer having an average thickness of 20 μm.
The term "average film thickness" as used herein refers to an average value obtained by using an eddy current film thickness meter (type mms) manufactured by Fischer and measuring 13 points at 20 mm intervals starting from 50 mm from the end.
All "parts" described below represent parts by weight.
[0148]
(Coating liquid for undercoat layer)
Alkyd resin 6 parts
(Beccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals, Inc.)
Melamine resin 4 parts
(Super Beckamine G-821-60, manufactured by Dainippon Ink and Chemicals, Inc.)
Titanium oxide (CR-EL, manufactured by Ishihara Sangyo) 40 parts
200 parts of methyl ethyl ketone
[0149]
(Coating solution for charge generation layer)
10 parts of a bisazo pigment having the structure shown in the following [Formula 1]
[0150]
Embedded image

Polyvinyl butyral 2 parts
200 parts of 2-butanone
Cyclohexanone 400 parts
[0151]
(Filler non-dispersed charge transport layer coating solution)
Bisphenol Z-type polycarbonate 10 parts
(Made by Teijin Chemicals: Z-Polyka Mv50,000)
8 parts of a low molecular charge transport material having the structure shown in the following [Chemical Formula 2]
[0152]
Embedded image

200 parts of tetrahydrafuran
[0153]
2) Preparation of filler-dispersed charge transport layer
The organic photoreceptor coated with the filler non-dispersed charge transport layer was dried by heating and then cooled, and subsequently, the filler dispersed charge transport layer was applied to a thickness of 2 to 10 μm by a spray coating method.
On the filler non-dispersed charge transport layer, the following four types of binder resin (bisphenol Z-type polycarbonate resin) and low molecular charge transport material (donor), primary particle diameters of 0.3, 0.5, 0.7 and 1 μm Prepare the following inorganic filler, put each inorganic filler and dispersing aid and solvent in a glass pot, disperse for 24 hours in a ball mill to make a coating solution, and reciprocate 1 to 5 times using a spray method, filler A dispersed charge transport layer was applied. After touch drying, the coating was dried by heating at 150 ° C. for 20 minutes to prepare an electrophotographic photosensitive member for evaluation having a filler-dispersed charge transport layer.
[0154]
[Filler-dispersed charge transport layer coating liquid]
Bisphenol Z-type polycarbonate 10 parts
(Made by Teijin Chemicals: Z-Polyka Mv50,000)
7 parts of a charge transport material represented by the following structural formula [Formula 3]
[0155]
Embedded image

Alumina filler 5.3 parts to 11.4 parts
(AA-02-10 manufactured by Sumitomo Chemical Co., Ltd., average primary particle size: 0.2 to 1.0 μm)
400 parts of tetrahydrofuran
Cyclohexanone 200 parts
0.08 parts of dispersing aid (BYK-P104 made by Big Chemie Japan)
Table 1 shows a list of the produced photoreceptors.
[0156]
[Table 1]

(Note) In the table, Rz _JIS Represents a 10-point average roughness, Rz represents a maximum height, and a filler particle diameter represents an average particle diameter.
[0157]
<Charging member>
Charging member for non-contact charging
φ7mm brass lot rod, electric resistance 4 × 10 ⁶ An epichlorohydrin rubber in which silica and fluororesin dispersed at Ω · cm (when 100 VDC is applied) is applied, polished and polished, and has a 10-point average roughness of 72 μm, a JIS-A hardness of 87 degrees and an outer diameter φ10 mm × 329 mm ( A charging member having an effective charging width of 308 mm) was prepared.
A non-contact charging member having a spacer of 49 mm in thickness, 7.5 mm in width and 31 mm in length cut into a diamond (PET) (polyethylene terephthalate) 1 mm inward from both ends of the charging member was prepared. The distance between the photosensitive member and the charging member was 62 μm on average.
[0158]
<Method of Applying Lubricant to Photoconductor Surface Layer>
A pulverized toner having a weight average particle size of about 4.8 μm and an average circularity of 0.924 (SiO 2 as a fluidizing agent) ₂ = 0.7%, TiO ₂ = 0.8%), 0.03% of zinc stearate (SZ2000) having an average particle diameter of 0.3 µm, or 0.17% by weight of tetrafluoroethylene (PTFE, Lubron L-2 Daikin Industries) is added. Thus, the method was performed by a method of applying a lubricant to the surface layer of the photoreceptor.
Note that a magnetic carrier (FPC-300LC) having a weight average particle diameter of 58 μm was used as a carrier of the developer.
[0159]
<Cleaning device>
1. Cleaning brush
Cut nylon fiber Bertron (made by Kubota Textile) and acrylic fiber SA-7 (made by Tsuchiya Co., Ltd.) with a fiber diameter of 15 denier, 48 filaments / 450 loops, and a loop length of 3 mm into a string with a width of 10 mm. Then, it was wound around a brass rod rod having a diameter of 5 mm and stuck and fixed using an adhesive, and five types of two cleaning brushes were produced.
Next, two of these were coated with resin to improve the fiber strength. The conditions are as follows: Toyo Polymer's water-based urethane adhesive Mersi 585 is used as the main agent, and similarly, Toyo Polymer's epoxy AD-C-65 is used as a curing agent, and ion exchange water is used as a diluting solvent so that the viscosity becomes 41 mPa · S. The cross-linking agent was immersed 2 mm from the surface of the cleaning brush in a liquid obtained by adding 1.25 water to 5 parts by weight of the main agent so that the addition amount of the cross-linking agent was 5% by weight. Drying was performed at 10 ° C. for 10 minutes.
[0160]
2. Cleaning blade
A strip (sheet) polyurethane rubber having a JIS-A hardness of 77 degrees, a thickness of 2 mm, a width of 11.6 mm and a length of 326 mm is applied to an L-shaped iron member having a thickness of 1 mm and a length of 363 mm with a hot melt adhesive. The attached one was used. The free length is 8 mm.
[0161]
<Evaluation method>
As a device for evaluation, a four-tandem color laser printer (Epsio Color 8000 (28 sheets / min.) Equipped with four photoconductors, four developing units of Y, M, C, and Bk and one transfer belt. Made). However, in the experiment, a dummy drum was mounted at the positions of Y, M, and Bk, and cyan toner was put at the position of C, and the evaluation was performed. As a means for applying a lubricant to the photoconductor, zinc stearate was contained at 0.03% by weight based on the toner.
The evaluation number was 50,000 sheets for each A4 size. The initial photosensitive layer thickness and the film thickness after 50,000 sheets were measured at 13 points at intervals of 20 mm using an eddy current film thickness meter (type mms, manufactured by Fisher). The abrasion loss of the photosensitive layer (average value at 13 points) was evaluated.
[0162]
<Examples 1 to 4>
As compared with the photoreceptor samples described in Table 1, the particle diameters of the fillers added in the filler-dispersed charge transporting layer differed from those of the photoreceptor samples. Four samples of 4, 8, 9, and 12 were selected and used for evaluation. The mounting position of each photoconductor was only the cyan position, and dummy photoconductors having equivalent characteristics were mounted at the other three locations. For charging, a non-contact charging roller is mounted, and a direct current voltage of -770 V and a peak-to-peak voltage (Vp-p) of 1850 V / 1350 Hz AC voltage are applied to the charging member in a superimposed manner, and the charging position is -700 to -710 V. It was set to become. At this time, the image portion potential of the photoconductor was -50 to -80 V for the four photoconductors. The developing bias was set at -600V.
The cleaning device was composed of a cleaning blade and a cleaning brush. The rotation direction of the cleaning brush was opposite to the rotation of the photoconductor (forward direction), and the brush was not provided with a flicker bar.
Ricoh cyan toner having a melting point of 160 ° C. was used as the toner, and a lubricant (zinc stearate) was added in an amount of 0.03% by weight to adjust to 5% by weight with respect to the carrier (FCP-300LC). .
The number of evaluation sheets was 50,000 sheets of A4 size.
[0163]
Evaluation items were I) coefficient of friction, II) uniformity of 1-dot halftone image (using internal pattern of printer), III) photoreceptor appearance characteristics (confirmation of filming), IV) abrasion amount of photosensitive layer (Fischer film) Thickness mms), V) Resolution (using Kodak A (JIS Z6008)) and surface roughness (10-point average roughness Rz) _JIS , The maximum height Rz), and the effect of a nylon cleaning brush (Beltron brush), which is intended to enhance the abrasion force when the lubricant is constantly applied to the photoreceptor, was confirmed. Table 2 shows the results.
[0164]
After 50,000 sheets, the surface layer of the photoreceptor was still glossy, and the coefficient of friction was 0.3, which was good. As a result, the abrasion amount of the photosensitive layer was as small as 0.3 to 0.4 μm, which was good. Filming caused by toner and paper dust was not found in the image forming area, and there was no image bleeding phenomenon.
After the evaluation, the cleaning brush was removed, and after removing the toner sufficiently, the state of peeling of the resin was confirmed by an optical microscope.Although there was peeling, the resin was still sufficiently covered and the cleaning property was sufficient. Observed.
[0165]
[Table 2]

In the table, Rz _JIS , Rz represent the surface roughness, and Rz _JIS Represents a 10-point average roughness, and Rz represents a maximum roughness. The photosensitive layer abrasion amount represents the abrasion amount per 10,000 sheets after the evaluation of 50,000 sheets. One-dot halftone uniformity is an evaluation result for an A3 size image. The resolution indicates “vertical resolution / horizontal resolution”, and there is no practical problem if the resolution is 5.6 lines / mm or more.
In the judgment, there is no problem in practical use, and in the case of evaluation of 50,000 sheets, the problem is practically small, but it will be a problem in the future, and in the case of evaluation of 50,000 sheets, the practicality is low.
The same applies to the following tables.
[0166]
<Comparative Examples 1-4>
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. Photoconductors 4B having the same specifications as Nos. 3, 5, 10, and No. 4 were prepared, and each was mounted on a photoconductor unit for cyan. Replace the cleaning brush with the original cleaning brush that does not enhance the abrasion force, attach a normal loop brush, and apply film lubricant to the photoreceptor. Was carried out. The evaluation method is the same as in Examples 1 to 4. Table 3 shows the results.
In all of the cleaning brushes in which the abrasion force was not strengthened, band-like filming occurred. 7 (Rz _JIS = 1.2 μm, Rz = 1.75 μm) and No. 10 (Rz _JIS (0.93 .mu.m, Rz = 1.63 .mu.m), the filming after 50,000 sheets spread over the entire surface, and pale whitish stains were observed over the entire length of the charging roller. Filming was also observed in the other two photoconductors. 7 and No. 7 The degree was better than 10.
[0167]
[Table 3]

[0168]
<Comparative Examples 5 to 8>
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 1, 2, No. No. 8 manufactured with the same specifications as No. 8. 8B and No. Fifteen photoconductors were prepared, and each was mounted on a photoconductor unit for cyan. The cleaning brush used was a loop-shaped cleaning brush having the same specifications as those used in Examples 1 to 4 in which the abrasion force was enhanced, and a cyan toner as a developer to which zinc stearate was not added was used. The evaluation was performed in the same manner as in Examples 1 to 4, and the effect was confirmed when a cleaning brush with an enhanced abrasion force was used in a state where zinc stearate was not applied. Table 4 shows the results.
When the cleaning brush for enhancing the abrasion force was not used and the lubricant was not applied, the coefficient of friction was large, and as a result, the photosensitive layer was greatly worn. As a result of an increase in friction coefficient, distortion (twisting) of the cleaning blade occurred, and the amount of toner detachment increased. Therefore, in all of the photoconductors to which the filler was added, a filming phenomenon occurred. In this case, although toner was removed, filming did not occur because of abrasion.
[0169]
[Table 4]

[0170]
<Examples 5 to 8>
Filming generation and filming when the thickness of the non-dispersed charge transporting layer (charge transporting layer) is changed in the range of 10 to 40 μm and the toner is combined with a cyan toner in which zinc stearate is added to a loop brush with enhanced abrasion. The effect due to was evaluated. The evaluation method was the same as that described in Examples 1 to 4. Table 5 shows the results.
Even if the thickness of the photosensitive layer is changed, the effect of the loop brush with increased abrasion is maintained, and no filming is generated in all four samples. In this state, the resolution did not decrease. In the photoreceptor having a large film thickness (No. 14 photoreceptor), a decrease in the resolution is observed, and the character is thickened regardless of the image deletion, and the resolution is 5.0 lines / mm vertically and 5.6 lines / mm wide. Was.
[0171]
[Table 5]

[0172]
<Examples 9 to 11>
The lubricant added to the toner was changed from zinc stearate to polytetrafluoroethylene (PTFE), and the amount added to the toner was 0.15% by weight. Nos. Shown in Table 1 were used for the photoconductors for evaluation. Photoconductor Nos. 3 and 4 manufactured with the same specifications. 3B, no. 4C and No. The photoconductor of No. 6 was used, and the other conditions were evaluated in the same manner as in Examples 1 to 4. Table 6 shows the results.
Even if the lubricant was changed to zinc stearate, filming was successfully suppressed, and the result was good. The image quality was sharper than zinc stearate, and a sharp line image was exhibited. The coefficient of friction was 0.2, indicating that the wear of the photosensitive layer was less than when zinc stearate was used.
[0173]
[Table 6]

[0174]
<Examples 12 to 16>
Replace the loop brush with abrasion reinforced acrylic fiber SA-7, and use 5% by weight of cyan toner with 0.15% by weight of polytetrafluoroethylene (PTFE) added to the carrier. did. Nos. Shown in Table 1 were used for the photoconductors for evaluation. Nos. 4, 5, 6, 12, and 1 were manufactured with the same specifications as the photoconductors described in Nos. 4, 5, 6, 12, and 1. 4D, 5B, 6B, 12B and 1B were used, and other conditions were evaluated in the same manner as in Examples 1 to 4. Table 7 shows the results.
The results were the same as in Examples 1 to 4, and no filming was observed in any of the five samples, and there was no reduction in resolution. The coefficient of friction also remained at a low level, and the wear was small. However, no. The photoreceptor 1B had abrasion increased to 1.1 μm per 10,000 sheets, and no filming occurred, but the durability was insufficient. Other characteristics were good.
[0175]
[Table 7]

[0176]
<Examples 17 to 19>
・ Method of manufacturing photoconductor for evaluation
The photoreceptor used in the present invention was produced in the following manner.
An aluminum drum having a diameter of 100 mm, a length of 360 mm, and a thickness of 1 mm is subjected to dip coating using a coating liquid for an undercoat layer (UL) having the following composition, and then dried by heating at 130 ° C. for 30 minutes to form an undercoat layer of about 4 μm. Was formed.
Next, dip coating is performed using a coating liquid for a charge generation layer (CGL), and a 0.2 μm charge generation layer is formed by heating and drying at 150 ° C. for 25 minutes. Dip coating was performed using a working solution, and a charge transport layer of about 25 μm was coated by heating and drying at 140 ° C. for 30 minutes to produce an organic photoreceptor. On this photoreceptor, further put a binder resin and a donor, inorganic fine particles (metal oxide) having an average particle diameter of 0.3 or 0.5 or 0.7 μm or 1.0 μm, additives and a solvent into a glass pot, Dispersed in a ball mill for 24 hours to prepare a coating liquid having an average particle diameter of about 0.5 μm (measured by CAPA500 manufactured by HORIBA, Ltd.), and applied four times (approximately 1.2 to 1.5 μm / time) using a spray method. The resultant was dried by heating to form a coating layer having a thickness of about 5 μm, thereby completing an electrophotographic photosensitive member.
All parts described below represent parts by weight.
[0177]
(Coating liquid for undercoat layer)
Alkyd resin 6 parts
(Beccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals, Inc.)
Melamine resin 4 parts
(Super Beckamine G-821-60, manufactured by Dainippon Ink and Chemicals, Inc.)
Titanium oxide (CR-EL, manufactured by Ishihara Sangyo) 40 parts
200 parts of methyl ethyl ketone
(Coating solution for charge generation layer)
Oxo titanium phthalocyanine pigment (Ricoh) 2 parts
0.2 parts of polyvinyl butyral (UCC: XYHL)
50 parts of tetrahydrofuran
[Coating liquid for charge transport layer (non-inorganic filler non-dispersed charge transport layer)]
Bisphenol A type polycarbonate 10 parts
(Z-Polyka manufactured by Teijin Chemicals Limited)
12 parts of a low-molecular-weight charge transport material having the structure shown in the following [Formula 4]
[0178]
Embedded image

100 parts of methylene chloride
1 part of methylphenyl silicone oil (50cs)
(Coating liquid for filler-dispersed charge transport layer)
The coating liquid for the filler-dispersed charge transport layer is prepared by mixing the binder resin and the inorganic fine particles in a weight ratio of 20% and the charge transport material to the binder resin in a ratio of 7/10, and using cyclohexanone as a solvent by a spray method. Three sprays were performed to form four coating layers.
Binder resin: 10 parts of polycarbonate resin
(Z Polyka, Teijin Chemicals, Mv50,000)
Filler: 5.7 parts of alumina powder
(AA-03, AA-05, AA-07, AA-10, manufactured by Sumitomo Chemical Co., Ltd.)
However, for AA-07, a photoconductor (sample No. 20) in which 11.4 parts were added in addition to 5.7 parts was prepared.
7 parts of a low molecular charge transport material shown in the following [Formula 5]
[0179]
Embedded image

Dispersing aid: (BYK-P104, manufactured by BYK Japan) 0.1 part
700 parts of tetrahydrafuran
Cyclohexanone 200 parts
Table 8 shows the measurement results of the produced photoreceptor.
[0180]
[Table 8]

As an evaluation device, Imagio Neo600 ((60 sheets / min) manufactured by Ricoh) was prepared by modifying the charging device for a non-contact charging roller.
The non-contact charging member used for charging the photoreceptor was made of epichlorohydrin rubber having the same specification as that described in the above embodiment, and finished to an outer diameter of φ18 mm. A 10 mm wide rhombic PET (polyethylene terephthalate film) having a thickness of 49 μm was attached to both ends of the charging roller thus produced with a double-sided tape to form a spacer. Incidentally, the gap between the photosensitive member and the charging member was about 61 μm.
On the other hand, a nylon beltlon having a width of 12 mm cut into a strip shape was spirally wound around a metal core and fixed with an adhesive to prepare a cleaning brush having an outer diameter of 18 mm and a loop length of about 3.5 mm.
These members are mounted on an evaluation device, and a DC voltage of -760 V and an AC voltage of 1800 V / 1500 Hz are superimposed and applied to the charging member, and the DC voltage is finely adjusted so that the charging position is -700 to -710 V. , And a 100,000 sheet passing evaluation was performed. Incidentally, the image portion potential was -150 V to -180 V.
As a developer, a toner obtained by adding 0.02% of zinc stearate to a black toner for Imagio Neo600 was used. Table 9 shows the results.
Filming was not generated in any of the photoreceptor samples, and the gloss was kept relatively good. In addition, the resolution was good, and the sharpness was slightly lowered compared to the initial stage, but the results shown in Table 9 were obtained, and all samples had no problem. In addition, although the resin coating layer of the loop brush was partially peeled off, it was not in such a condition as to deteriorate the cleaning property.
[0181]
[Table 9]

In the table, the abrasion amount of the photosensitive layer indicates the abrasion per 10,000 sheets converted to a photoreceptor having a diameter of 30 mm.
[0182]
<Comparative Examples 9 to 10>
As a photoreceptor for evaluation, No. 1 shown in Table 8 was used. Using the photoconductors of Nos. 19 and 20, evaluation was made in the same manner as in Examples 17 to 19. Table 10 shows the results.
Surface roughness increases (Rz _JIS Is 1.0 or more and Rz is 1.5 or more), the toner blade detachment is increased, the abrasion force of the cleaning brush is insufficient, and filming is locally observed.
For this reason, the image quality (unevenness in the halftone image, locally reduced resolution, and crushing of the character image due to fatness) was reduced.
[0183]
[Table 10]

In the table, the abrasion amount of the photosensitive layer indicates the abrasion per 10,000 sheets converted to a photoreceptor having a diameter of 30 mm.
[0184]
【The invention's effect】
As apparent from the detailed and specific description above, the configuration according to claim 1 of the present invention allows the ten-point average roughness Rz _JIS The cleaning brush and the cleaning blade are simultaneously operated while applying a lubricant to a photosensitive member having a diameter of 0.3 to 1.0 μm and a maximum height Rz of 0.4 to 1.5 μm. By keeping the abrasion amount of the photosensitive layer per sheet at 0.1 to 0.5 μm from the surface layer, poor cleaning of residual powder (consisting of toner, paper dust, dust, etc.), corona product, etc. Filming caused by the action can be prevented, and the coefficient of friction of the surface layer of the photoreceptor is maintained at a low level, so that there is no degradation in image quality such as resolution reduction, image deletion, etc., and the wear of the photosensitive layer is also low. As a result, it is possible to maintain an image with good sharpness and no unevenness for a long period of time. According to the second aspect of the present invention, a loop brush is formed by using any one of polyester fiber, nylon fiber, and acrylic fiber as a cleaning brush, and is brought into surface contact with the photoreceptor and rubbed. By arranging, the residual powder on the photoreceptor can be stably cleaned for a long period of time, and by strengthening the fiber, filming on the photosensitive layer can be uniformly removed. In the cleaning brush according to the third aspect of the present invention, the cleaning brush can be easily and quickly manufactured by taking a means for spirally winding and fixing the loop brush cut into a strip shape on the core bar without any gap. Can be. The brush produced in this manner does not slip off and guarantees stable cleaning of the residual powder over a long period of time. According to the fourth aspect of the present invention, at least the fibers in the area used for cleaning the loop-shaped cleaning brush are coated with a resin and mechanically strengthened, so that the filming fixed to the photosensitive layer is rubbed by the cleaning brush. The force not only cleans the residual powder, but also removes the fine filming generated to a small extent to prevent spreading, so that a high-quality image can be maintained for a long period of time. According to the fifth aspect of the present invention, by applying the resin layer for mechanically reinforcing the loop-shaped brush by the dipping method, it is possible to easily and surely perform sufficient resin coating. The cleaning performance can be maintained for a long time. Further, according to the configuration of the sixth aspect, by not using the flicker bar for the loop brush, it is possible to prevent the toner from accumulating inside the brush and lowering the cleaning function. Further, since there is no mechanical damage due to the flicker bar, good cleaning properties can be maintained for a long time. Further, by rotating the loop brush in a direction opposite to the rotation of the photoconductor, excessive shaving of the photoconductive layer and uneven wear are reduced, and a long life of the photoconductor is achieved. Further, occurrence of an abnormal image can be avoided. According to the eighth aspect of the present invention, a filler having a particle size of 0.3 to 0.7 μm is added in an amount of 20% by weight or more and 35% by weight or less in order to achieve abrasion resistance in the charge transport layer of the photoreceptor. Even if a reinforced loop brush is used, the photosensitive layer will not be unnecessarily abraded, an image with good resolution and sharpness can be formed, and the life of the photosensitive member can be extended. According to the ninth aspect of the present invention, the coefficient of friction can be reduced by using either zinc stearate or polytetrafluoroethylene as the lubricant to be applied to the surface of the photoreceptor. By maintaining the value between 2 and 0.45, the sharpness is good and the photosensitive layer can be prevented from being unnecessarily worn. Further, since the lubricant enters the valley portion of the photoreceptor surface appropriately, the adhesion of the corona product is suppressed, which is a measure for suppressing the image deletion. Further, by using a contact charging roller that forms a nip with the photoconductor as a means for charging the photoconductor, charging with low voltage and good image uniformity is performed. High S / N image quality with high uniformity can be guaranteed. According to the configuration of claim 11, as a means for charging the photoreceptor, by maintaining a small gap between the photoreceptor and the charging member at 30 μm or more and 100 μm or less, contamination of the charging roller is reduced, and Since pinholes due to a small metal such as a carrier piercing the carrier are reduced, the margin for discharge breakdown is increased. In addition, stable charging can be performed. According to a twelfth aspect of the present invention, there is provided an electrophotographic photosensitive member according to any one of the first to eleventh aspects, a charging device, a cleaning device including a cleaning brush and a cleaning blade, and an indirect method using a lubricant applying unit. By using an image forming method using electrophotography, an image with good sharpness without filming is formed, and since there is no excessive wear of the photosensitive layer, a stable image can be provided for a long time. . Further, according to the structure of claim 13, at least one unit selected from the electrophotographic photosensitive member according to claim 1 to claim 11, a charging device, a cleaning device including a cleaning brush and a cleaning blade, and a lubricant application unit. The image forming apparatus can be removed and mounted in a short time when an abnormal image occurs or the unit reaches the end of its life by configuring a process cartridge that is detachable from the image forming apparatus. Because of this, it is possible to reliably return to the original state.
[Brief description of the drawings]
FIG. 1 is a schematic view of an image forming apparatus illustrating a copying process of the present invention including a cleaning device including a cleaning brush and a cleaning blade without a flicker bar.
FIG. 2 is another schematic diagram of an image forming apparatus illustrating a copying process of the present invention including a cleaning device including a cleaning brush and a cleaning blade without a flicker bar and a device for applying a lubricant to the surface of a photosensitive layer. FIG.
FIG. 3 is a schematic view of a four-tandem tandem type color laser beam printer using four photoconductors and developing devices of four colors of magenta, cyan, yellow and black.
FIG. 4 is a schematic diagram illustrating a configuration of a function-separated type photoconductor used in the present invention.
FIG. 5 is a schematic diagram illustrating a function-separated type photoconductor in which the charge transport layer in FIG. 4 is composed of two layers, a filler non-dispersed charge transport layer and a filler dispersed charge transport layer.
FIG. 6 shows the surface roughness (10-point average roughness Rz) of the photoconductor surface layer. _JIS , Is a graph illustrating the dependence of the maximum height Rz) on the filler particle size.
FIG. 7 shows the surface roughness (10-point average roughness Rz) of the surface layer of a photoreceptor of a φ60 mm photoreceptor. _JIS 4 is a graph illustrating the dependency of the maximum height Rz) on the amount of filler added to the charge transport layer.
FIG. 8 shows the surface roughness (10-point average roughness Rz) of the surface layer of a photoreceptor of a φ30 mm photoreceptor. _JIS 4 is a graph illustrating the dependency of the maximum height Rz) on the amount of filler added to the charge transport layer.
FIG. 9 is a schematic diagram illustrating a state in which fibers of a cleaning brush used in the present invention are woven in a loop shape.
FIG. 10 is an external view of a cleaning brush used in the present invention.
FIG. 11 is a schematic view showing an arrangement of a cleaning device for explaining a combination of a strip-shaped cleaning blade and a cleaning brush.
FIG. 12 is a schematic diagram showing an arrangement of a cleaning device for explaining a combination of a knife-edge-shaped cleaning blade and a cleaning brush.
FIG. 13 is a schematic view showing a contact state of a strip-shaped cleaning blade.
FIG. 14 is a schematic diagram illustrating a contact state of a knife-edge-shaped cleaning blade.
FIG. 15 is a schematic view of a charging roller for a non-contact charging device used in the present invention.
[Explanation of symbols]
1: Photoreceptor for electrophotography (photoreceptor)
2: Charging device
3: Image exposure device
4: Developing device
5: transfer device
6: Separation device
7: Cleaning device
7-1: Cleaning brush
7-2: Cleaning blade
8: Fixing device
9: Copy paper
20: Charger
200: Lubricant application device
201: Lubricant
202: Brush with lubricant

Claims (13)

A voltage is applied to a charging member constituting a charging device arranged so as to face the electrophotographic photosensitive member to uniformly charge the electrophotographic photosensitive member, and an electrostatic latent image is formed by optical writing from an image exposure device. Formed, the electrostatic latent image is visualized by a developing device, transferred to a transfer target by a transfer device to which a voltage is applied, and is transferred onto a photosensitive member by using a cleaning device including a cleaning brush and a cleaning blade. In the image forming apparatus using indirect electrophotography, which forms an image by cleaning the residual powder, the 10-point average roughness Rz _JIS is 0.3 to 1.0 μm and the maximum height Rz is 0.4. By applying a lubricant to the surface of the electrophotographic photosensitive member having a diameter of about 1.5 μm and simultaneously operating a cleaning brush and a cleaning blade, (φ30 An image forming apparatus for forming an image by maintaining an average wear amount (t) of a photosensitive layer per 10,000 sheets (in terms of an electrophotographic photosensitive member of 0.1 mm) within a range of 0.1 μm ≦ t ≦ 0.5 μm. . The cleaning brush is one in which a loop brush composed of any one of polyester fiber, nylon fiber and acrylic fiber is fixed on a cored bar, and the cleaning brush is attached to the electrophotographic photosensitive member. The image forming apparatus according to claim 1, wherein the image forming apparatus is installed in the cleaning device so as to make uniform surface contact. The means for fixing the loop brush on the metal core is such that the strip-shaped loop brush is spirally wound around the metal core without any gap, and the cleaning brush is located on the front side of the cleaning blade. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed in a cleaning device so as to make uniform surface contact with the electrophotographic photosensitive member. 4. The image forming apparatus according to claim 1, wherein a resin is applied to a surface of the cleaning brush that comes into contact with the photoconductor and an inner direction of the cleaning brush. 5. The image forming apparatus according to claim 4, wherein the resin is applied to a surface of the cleaning brush that contacts the photoconductor and to an inside of the cleaning brush by an immersion method. The image forming apparatus according to claim 1, wherein a flicker bar is not provided on the cleaning brush. 7. The cleaning brush according to claim 1, wherein the cleaning brush rotates in a forward direction with respect to the rotation of the electrophotographic photosensitive member, and rubs the cleaning brush to remove the residual powder on the electrophotographic photosensitive member. An image forming apparatus according to any one of the above. The photosensitive layer constituting the electrophotographic photoreceptor includes a charge generation layer and a charge transport layer, and the charge transport layer further includes an inorganic filler non-dispersed charge transport layer containing no inorganic filler, and an inorganic filler dispersed charge transport layer. The inorganic filler dispersed in the charge transport layer, wherein the inorganic filler having an average particle size of 0.3 to 0.7 μm comprises 20% by weight or more and 35% by weight or less of the entire charge transport layer containing the inorganic filler. The image forming apparatus according to claim 1, wherein: By applying either a zinc stearate or a polytetrafluoroethylene (PTFE) lubricant to the surface layer of the electrophotographic photoreceptor using a direct or indirect coating means, the friction coefficient can be reduced. 9. The image forming apparatus according to claim 1, wherein a coefficient of friction measured by an Euler belt method is 0.20 to 0.45 during image formation. The image according to any one of claims 1 to 9, wherein charging of the electrophotographic photosensitive member at the time of forming an electrostatic latent image is performed by surface contact of a charging member having a nip with the electrophotographic photosensitive member. Forming equipment. 4. The method according to claim 1, wherein the charging of the electrophotographic photosensitive member at the time of forming the electrostatic latent image is performed by keeping a charging member and the electrophotographic photosensitive member in a non-contact state with a distance of 30 to 100 [mu] m. 10. The image forming apparatus according to any one of 9 above. 12. Forming an image using an electrophotographic photoreceptor, a charging device, a cleaning device including a cleaning blade and a cleaning brush, and a lubricant applying unit used in the image forming apparatus according to claim 1. An image forming method by an indirect electrophotographic method, characterized by comprising: An at least one selected from an electrophotographic photosensitive member, a charging device, a developing device, a cleaning device including a cleaning brush and a cleaning blade, and a lubricant applying member used in the image forming apparatus according to claim 1. A process cartridge which integrally supports two units and is detachable from an image forming apparatus main body.

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