JP3936647B2 - Image forming apparatus, image forming method, and process cartridge - Google Patents

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、初期及びＡ４サイズペーパー５万枚印字後の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Ａ４サイズペーパー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、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、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２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３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４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５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６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７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８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９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１０の構成によって、請求項１〜請求項９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１１の構成によって、請求項１〜請求項９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]
BACKGROUND OF THE INVENTION
The present invention obviates the filming phenomenon caused by the corona product, paper dust, toner, etc. adhering to the photoreceptor, and maintains good image quality without causing resolution reduction and image flow. The present invention relates to an image forming apparatus, an image forming method, and a process cartridge.
[0002]
[Prior art]
In a desktop type or floor type image forming apparatus using indirect electrophotography such as a facsimile, a laser printer, an electrophotographic copying machine, etc., an electrophotographic photosensitive member (hereinafter simply referred to as a photosensitive member), a charging device, and an image in order. An exposure device, a developing device, a transfer device, a separation device, a cleaning device, a static elimination device, and a fixing device are arranged to perform image formation.
Conventionally, the photoreceptors include zinc oxide (ZnO), cadmium sulfide (CdS), cadmium selenide (CdSe), amorphous selenium (a-Se, a-Se-Te, a-As). ₂ Se ₃ In recent years, inorganic photosensitive materials such as amorphous silicon (a-Si: H) have been used, but in recent years they are easy to fabricate, can be designed with high sensitivity, have low cost, and are free from pollution. Organic photoreceptors are mainly used.
[0003]
The structure of the organic photoreceptor can be classified into a functional separation type in which the photosensitive layer is composed of two layers, a charge transport layer and a charge generation layer, and a layer structure in which a charge generation material and a charge transport material are mixed. Most of the layer structures of photoreceptors distributed in the market are function-separated type photoreceptors, and the basic layer structure of the photoreceptor is an undercoat layer, an electric charge on a conductive support such as aluminum in order. The generation layer and the charge transport layer are layered in this order.
[0004]
Examples of means for applying a charge necessary for image formation to the surface of the photoreceptor include a scorotron-type corona charging method having a grid, and a contact charging method in which a charging member such as a brush, roller, or blade is placed 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 disposed about 30 to 100 μm apart.
A DC voltage or a DC voltage superimposed with an AC voltage is applied to the charging device, and the photosensitive member is charged to about 400 to 800V. In a function-separated type organic photoreceptor, it is usually negative (−) charged.
[0005]
[Patent Document 1]
JP 2001-318475 A (3rd page, 4th column, 8th line to 24th line)
[0006]
For the photoconductor that has completed the charging process, optical writing of an original image (in the case of the digital method, an LD (Laser Diode) or LED (Laser Emitting Diode) is used as a light source irradiated to the photoconductor, and a dot pattern image is used. Is formed, and an electrostatic latent image is formed in the photosensitive layer.
Next, the electrostatic latent image is visualized by a developing device of a reversal development method (the exposed portion is represented as an image, and the charge level is expressed as a background portion), transferred to a copy sheet by a transfer device, and a fixing device. To hard copy. On the other hand, the toner remaining on the photoreceptor after the transfer is cleaned on the photoreceptor surface by the cleaning device, and the series of image forming processes is completed.
[0007]
Incidentally, a cleaning device for cleaning toner is generally a blade-type cleaning device using a rubber material.
The blade is made of polyurethane rubber, which is excellent in terms of cleaning and durability. Rubber materials such as neoprene rubber, chloroprene rubber, silicone rubber, and fluororubber are easy to adhere to an object with high smoothness as used for packing. Polyurethane rubber is no exception. Therefore, when used as a cleaning blade for a photoreceptor, the edge portion cut into a rectangle is pressed and fixed so as to be in line contact with the surface of the photoreceptor.
However, even if it is set to be in line contact, the blade actually contacts the photoconductor with a nip because of the pressure and the elasticity of the blade material, so-called surface contact. It will be in close contact. Therefore, although the cleaning performance can be further improved, the contact area with the photoconductor increases, so that the frictional resistance increases and it is almost impossible to rotate the photoconductor.
[0008]
In order to rotate the photoconductor, it is necessary to apply a powder for reducing contact resistance, such as toner or polyvinylidene fluoride, to the tip of the blade before mounting the photoconductor.
However, since the fine powder is insufficient at the edge portion in contact with the photoconductor, the vibration phenomenon that the tip (edge) of the blade is non-uniformly dragged and returned in the rotation direction of the photoconductor, that is, the stick- A slip phenomenon occurs. Due to this stick-slip phenomenon, a slight gap of several μm to several tens of μm may be generated between the photosensitive member and the photosensitive member.
For this reason, if the toner particle size is smaller than this gap, a phenomenon in which a part of the toner sent from the next to the blade at the blade is removed from the gap, so-called toner omission or poor cleaning occurs.
[0009]
The toner used as a developer at the time of image formation is a pulverized toner having an average circularity of about 0.91 to 0.94, and an average circularity of about 0. A polymerization toner having a spherical shape of 96 to 1.0 or a spherical shape 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 sieving, but cannot be made to have a constant particle size, and crushing also occurs, so that the particle size distribution becomes as large as about ± 3 to 4 μm. Accordingly, the developer always contains a large amount of toner having a minute particle diameter of 1 to 2 μm. For this reason, in the toner having an average particle diameter of 4 μm, the toner having a particle diameter as small as about 1 to 2 μm is removed from a slight gap caused by unevenness of the surface of the photoreceptor or twisting of the blade. The charging member is contaminated, which causes a reduction in 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 in particle size is small. Therefore, even if the surface of the photoreceptor has irregularities of about 2 μm, the toner having an average particle diameter of 4 μm hardly escapes. However, since the shape is spherical, the toner tends to sink under the blade as compared with the pulverized toner, and a toner omission phenomenon different from that of the pulverized toner occurs.
[0010]
Filming is likely to occur when there is a lot of toner missing or toner scattering. This is because the toner, which is the main factor of filming, is strongly pressed against the photoconductor due to the blade edge, so that the resin and additives that constitute the toner are exposed to the surface of the photoconductor by the pressure of the blade and frictional heat. This is thought to be due to fusing. However, since the filming phenomenon involves paper dust or corona products from the transfer object, it is important to eliminate these factors.
Filming is hard to wear because it adheres firmly to the photosensitive layer. Therefore, once formed, it is difficult to scrape off with a blade or developer. In particular, when a blade has been used for a long time, the edge portion is worn, and the surface of the photoreceptor is rough and the surface roughness is high. Become. Therefore, the filming film gradually increases in thickness as the film thickness increases. When the filming is formed, the coefficient of friction of the surface layer of the photosensitive member is also increased, so that the formation of filming is further increased.
When filming is formed on the photoconductor, it is difficult to remove the corona product attached to the filming surface. When the corona product on filming absorbs moisture in the atmosphere, the filming surface becomes low in resistance, gradually lowering the resolution of image quality, and finally results in a 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, the light attenuation characteristic is affected, and an uneven image is formed.
[0011]
In addition to the blade cleaning device described above, a cleaning device using a cleaning blade and a cleaning brush is used as the cleaning device. The cleaning brush has a function of forcibly cleaning foreign matter that is difficult to remove even with a blade, but a thin film that is strongly adhered to the surface of the photoreceptor, such as filming, can hardly be removed.
Therefore, once the filming formed on the photoconductor is formed, the filming is gradually deposited, so that it becomes more difficult to remove and seriously affects 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 or scraping the traces each time before the filming film spreads. In order to completely block the toner over a long period of time by increasing the frictional resistance between the blade and the photoconductor, the load on both the photoconductor and the blade becomes large. Therefore, the rotation of the photosensitive member becomes unstable, and the blade is liable to cause a stick-slip phenomenon. With the means for forcibly scraping off using an abrasive or the like, the photosensitive layer may be greatly worn and the life of the photoreceptor may be shortened.
[0013]
An example of disclosure that describes means for avoiding filming caused by toner is shown below.
A cleaning device comprising a cleaning blade and a cleaning brush is used, a carrier having conductivity (unknown electrical resistance) is used as a developer, and a conductive seal (10 in the embodiment) is located upstream from the blade. ³ Ω · cm), the contact width with the photoconductor is 5 to 15 mm, and an AC voltage of 200 to 1000 Hz and 400 to 1000 V is applied, resulting in damage due to the carrier being pressed against the photoconductor and poor cleaning. Toner filming is improved so as to obtain a stable copy quality over a long period of time (see, for example, Patent Document 2).
[0014]
[Patent Document 2]
JP-A-5-313540 (Claim 2 on page 2, column 1, lines 2 to 10)
[0015]
In this method, the carrier is neutralized by a seal provided at the inlet of the cleaning device, and the electrostatic force is weakened to prevent the carrier from entering the blade, thereby efficiently cleaning the toner and the carrier. .
Although this method has an effect of removing the charge of the toner and the carrier, the charge is eliminated through the photosensitive member, so that the carrier is not sufficiently removed, and there is room for improvement in eliminating the carrier. In addition, when filming occurs once, there is no means for removing filming, so that the effect is insufficient.
[0016]
Damage to the photoreceptor by attaching and covering the surface of at least one of the photoreceptor and at least one of the blade or brush of the cleaning member with silicon rubber fine particles (0.05 to 5.0 μm, 1.8 μm in the embodiment). Filming is prevented (see, for example, Patent Document 3).
[0017]
[Patent Document 3]
JP-A-6-337535 (Claim 3 on page 2, column 1, lines 12 to 19; page 3, column 4, line 5 to column 3, line 33, page 4) (6th column 1st line-22nd line)
[0018]
In this method, the silicon rubber fine particles are finally carried to the blade, but since it is an elastic body, even if it is pressed against the gap between the blade cut surface and the photoconductor, the photoconductor is not damaged.
In addition, the toner is blocked by filling the gap, and the toner is prevented from coming off to the charging member side, so that the cleaning can be performed satisfactorily.
Although this means is highly effective in terms of toner cleaning properties, if the frictional resistance between the blade and the photoconductor is large, it is impossible to prevent gaps from being formed. There is a high possibility that the silicon rubber fine particles that have escaped from the gap will adhere to the charging member or enter the developer, and there is a risk that the charging characteristics of the toner will become unstable.
Further, by adding silicon rubber, a large amount of silicon rubber gets into the toner, which is likely to cause image defects.
[0019]
A cleaning roller having a 10-point average roughness Rz of 3 to 20 μm is brought into contact with the cleaning brush (a roller for scraping the lubricant and supplying it to the brush and for collecting the adhered lubricant). A lubricant is brought into contact with the collecting roller, and the lubricant is supplied to the photoreceptor via a cleaning brush, thereby preventing filming caused by the toner additive (see, for example, Patent Document 4).
[0020]
[Patent Document 4]
Japanese Patent Laid-Open No. 10-74028 (Summary of the first column to the left column, the first line to the last line)
[0021]
This means is to form a lubricant (eg, zinc stearate) film 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 easy to apply a thick film, so that a corona product is easily taken into the lubricant, so that there is a problem that image flow is likely to occur. Therefore, when using zinc stearate, a supply method is required so as to form an extremely thin film that can be easily removed.
Further, since zinc stearate is a wax, the collection roller easily clogs, and it is difficult to maintain it as a collection 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 symbols 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 photoconductor with a direction perpendicular to or substantially perpendicular to the photoconductor rotation axis direction (see, for example, Patent Document 5). .
[0022]
[Patent Document 5]
JP 2000-352832 A (2nd page, 1st column, 2nd line to 27th line, claims 1 to 6)
[0023]
Lubricant and anti-wear agent (Al ₂ O ₃ , SiC, SiO ₂ , B ₄ By providing an insulating layer in which the resin is dispersed in a resin, the surface of the photoreceptor is adjusted with a lubricant while the low-resistance material adhering to the surface of the photoreceptor is removed with a wear reducing agent (for example, Patent Document 6). reference.).
[0024]
[Patent Document 6]
JP-A-56-99347 (second page, lower right column, line 5 to page 3, upper left column, fourth line)
[0025]
Although the low resistance substance formed on the photoconductor by the lubricant can be removed, the above material has a function similar to that of a paper file, and thus has a drawback of high wear. In addition, the lubricant that is removed from the insulating layer is stuck in the photosensitive layer and has a problem that an abnormal image such as a white spot or a black spot is likely to occur.
[0026]
Fiber used for cleaning brush (conductive fiber, 50-200 bundles / inch ² , 2000-20000 pieces / inch ² ) Is specified, and an AC voltage higher than the start of discharge is applied to effectively clean paper dust, copy paper fibers, etc. that are difficult to remove with a cleaning blade, making filming difficult. (For example, refer to 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 adhesiveness of the toner to the photoconductor is reduced, so that the cleaning performance is improved as compared with the conventional case. However, since the improvement to the blade has not been achieved, it has passed through the brush and reached the blade. The toner is not sufficiently suppressed by the blade, and although the time until the phenomenon occurs is delayed, the filming is not sufficiently improved.
The filming phenomenon involves the surface roughness, hardness, cleaning blade, toner, and the like of the photoreceptor. Next, these will be described.
[0029]
1. Surface roughness of photoconductor
When the surface roughness of the photoconductor is low, the lower the surface roughness, the higher the blade adhesion when the surface roughness is small, but the higher the adhesion, the higher the frictional resistance with the photoconductor, Since the blade is easily deformed, the probability of toner loss increases. Therefore, it is desirable that the surface roughness is large enough to prevent toner loss in a range where good image quality can be obtained.
The surface roughness of the photoreceptor is 10 points average roughness Rz _JIS And there are items such as maximum height Rz, but 10-point average roughness Rz _JIS In this case, the image quality such as resolution and sharpness, and the maximum height Rz have a great significance for the cleaning property of the small particle size toner.
As the toner, a pulverized toner having an average particle size of about 4 to 8 μm and an average circularity of about 0.91 to 0.94 and a polymerized toner of 0.96 to 1.0 are usually used. For example, a pulverized toner having an average particle diameter of 4 μm includes a toner as small as 1 μm, and therefore the surface roughness of the photoreceptor must be at least 1 μm or less. If the maximum height Rz of the unused photoconductor is 1 μm or more, there is a possibility that toner may be missing from the first copy even if the blade is not twisted. However, since the surface valley is actually filled by twisting the blade edge due to the pressing of the blade, even if the maximum height Rz is 1 μm or more, the toner may not be removed immediately, but it cannot be suppressed. In such a case, the toner may come off, and when twisting occurs, the toner comes out at a level close to 100%.
[0030]
The following disclosure examples are examples in which the 10-point average roughness Rz is defined.
A 1 to 5 mm plate-shaped rubber plate having a JIS-A hardness of 55 to 75 degrees and a rebound resilience of 30 to 70% is brought into contact with the photoreceptor, and the photoreceptor has a surface roughness of 0 at an average roughness Rz of 10 points. By setting the thickness to 2 to 2.0 μm, preferably 0.3 to 1.5 μm, the toner can be prevented from slipping through even if the blade is turned up (for example, see Patent Document 8).
[0031]
[Patent Document 8]
JP-A-11-212212 (claims 1 to 3 on page 2, column 1, lines 2 to 22)
[0032]
If the frictional resistance between the photosensitive member and the cleaning blade is kept low, the blade is less likely to be deformed. However, if it is high, the stick-slip phenomenon of the blade is likely to occur, and is about 1 to 2 μm from the portion where the distortion or turning has occurred. A phenomenon that minute toner is removed occurs, which causes filming.
In the above disclosed example, since no lubricant is applied, it is expected that the frictional resistance between the photoreceptor and the blade is increased. Accordingly, when a blade having a low hardness of 55 to 75 degrees is used, the adhesion to the photoconductor is enhanced, but distortion and crushing are likely to occur in the region where the friction coefficient is high, and a gap is formed between the photoconductor and a minute amount. When toner is used, there is a high possibility that toner may slip through.
[0033]
2. Surface hardness of photoconductor
If the surface hardness of the photoconductor is low, filming is unlikely to occur because it is easily worn, but the photoconductive layer wears, so the life of the photoconductor is shortened, and in many copiers, etc., frequent replacement is not possible. Produce rationality. Therefore, it is desirable that the photosensitive layer has a higher hardness in order to extend the life of the photoreceptor.
The purpose of increasing the surface hardness of the photosensitive member is not only to achieve a longer life of the photosensitive member but also to reduce the biting of the cleaning blade into the photosensitive layer and to reduce the increase in frictional resistance to suppress the deformation of the blade.
[0034]
As described above, the organic photoreceptor has a single layer type in which the functions of the charge generation material and the charge transport material are integrally formed, and a two-layer configuration of the charge generation layer and the charge transport layer. There is a function separation type photoreceptor, and the latter function separation type photoreceptor is used in the present invention.
A general function-separated organic photoconductor comprises a charge generation layer directly on a conductive support or through an undercoat layer (or intermediate layer), and then a resin layer containing a charge transport material (charge transport). Layer) is formed.
On the other hand, a polycarbonate resin material (A-type, C-type, Z-type, etc.) having high resistance, high transparency, and low polarity dependency is suitably used as the binder resin material that is a constituent material of the charge transport layer. . Polycarbonate resin alone has high hardness and high wear resistance, but the photosensitive layer using polycarbonate resin has a Vickers hardness of 10-30 kg / mm. ² The pencil hardness decreases to about B and the tensile strength also decreases.
On the other hand, corona products such as ozone and nitrogen oxide (NOx) generated during charging are likely to adhere, and the free surface energy (or friction coefficient) is reduced. Therefore, since the frictional resistance with the cleaning blade is increased, the photosensitive layer is easily rubbed and worn. Furthermore, high-frequency noise (vibration noise) may be generated due to rubbing of the cleaning blade.
[0035]
When the film thickness of the photosensitive layer decreases, the capacitance increases and the charge level decreases. For this reason, if the potential difference between the charging potential and the developing bias potential is reduced, background stains are likely to occur.
If the potential difference between the development bias potential and the charge level is widened to prevent background stains on the copy from occurring, the potential difference between the development bias potential and the image portion potential inevitably decreases. 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, the user who has a large number of copies frequently changes the photosensitive member and related members. Therefore, it is necessary to suppress the wear and stabilize the image quality.
[0036]
Factors that affect the number of durable sheets include the image area of a document, the rubbing with a cleaning member, a developer, the pressure contact of toner, carrier, paper dust, and the like with the cleaning member, and the corona product generated during the charging. As the photosensitive layer wears, the electrostatic capacity increases, so the charge level decreases. Therefore, the margin between the charging potential and the developing bias potential is reduced, and the possibility of background contamination increases.
In a quadruple tandem color copier, the color of the four photoconductors varies depending on the original color, image area, developer feed amount, toner amount, etc. Appears as a drop in color reproducibility.
Improving the wear resistance of the photoreceptor guarantees a reduction in total cost and reliability for image quality. Therefore, it is important to increase the durability of the photoreceptor.
The technology to make the photoreceptor highly durable includes 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 some disclosed examples of means for improving the durability.
It is described that it 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 (see, for example, Patent Documents 9 and 10). .)
[0038]
[Patent Document 9]
Japanese Patent 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 2 on page 2, column 1, lines 2 to 12)
[0040]
Abrasion resistance can be improved by dispersing an appropriate amount of high-hardness conductive fine particles in the photosensitive layer. Use of low-resistance fine particles is effective for charge injection charging. However, when using the hazard contact charging method, image flow tends to occur and it is difficult to achieve both resistance to image quality degradation.
[0041]
Inorganic compound particles of 0.02 to 5 μm (preferably 0.07 to 2.0 μm), 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 it is composed of a photosensitive layer containing a transport material (see, for example, Patent Document 11).
[0042]
[Patent Document 11]
JP 08-123053 (page 3, column 3, line 42 to line 49)
[0043]
This means can disperse high-resistance inorganic compound particles excluding silica in the photosensitive layer, thereby improving wear resistance and ensuring charging ability. By including a butadiene-based charge transport material in the photosensitive layer, charge mobility can be maintained in the same manner as in the charge transport layer, so that the sensitivity reduction is small and problems related to charging and sensitivity can be eliminated to some extent. However, trapping sites are easily formed between the particles and the binder resin, so that if they are simply contained, residual potential accumulates due to repeated use, resulting in deterioration of light attenuation, and gradually lowering the image density and causing image unevenness. . In addition, when a filler having a large particle size is used, the sharpness of the line image is reduced. On the other hand, the surface roughness of the photosensitive member is increased, and the difference between the maximum value and the minimum value is larger than the toner particle size. Leading to poor cleaning. In addition, the edge of the cleaning blade is easily deformed, and there is a problem that toner and corona products are likely to be poorly cleaned.
When silica is used, the resistance of the photosensitive layer is drastically reduced due to the oxidizing action by ozone, and the image is caused to flow even in a normal humidity environment of about 60% RH. A heat source for heating to a certain degree is indispensable.
[0044]
Silicone resin, phenolic resin, SiO 2 having a particle size of 1 to 3 μm on a charge transport layer having a thickness of 12 μm or less ₂ (Silica), Al ₂ O ₃ (Alumina), TiO ₂ It is described that the photosensitive layer is composed of (titanium oxide) and ZnO (zinc oxide) dispersed (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 7)
[0046]
This means is a means to achieve high wear resistance by using a filler with a large particle diameter, but since the particle diameter of the particle is large, the surface roughness of the photoreceptor surface layer is increased, and the sharpness of the image edge is increased. Lack of. In addition, when the blade cleaning method is used, the edge is distorted and the toner is lost, and the image quality of the copy paper is likely to be deteriorated and the background stains are likely to occur. Furthermore, the blade edge is chipped, and the durability of the cleaning blade cannot be maintained.
[0047]
It is described that it comprises a photosensitive layer in which fine particles of inorganic compounds 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.) In addition, in the image formation using a photoconductor including inorganic fine particles such as silica of 0.05 to 2 μm in the resurface layer, it is described that residual toner is removed by cleaning with a rubber blade and a brush-like cleaning member ( For example, see Patent Document 14.)
[0048]
[Patent Document 13]
Japanese Patent Application Laid-Open No. 08-146641 (Claim 2, first column, second line to eighth line, claim 1, second column, 31st line to 42nd line)
[Patent Document 14]
JP-A-8-314175 (claims 1 to 4 on page 2, column 1, lines 2 to 14)
[0049]
Since these means use a filler having a small particle diameter, image quality deterioration due to particles is small, and high durability can be achieved. However, when silicon oxide is used, almost 100% image flow occurs due to the low resistance caused by ozone. In a region where the particle size is small (for example, 0.1 μm or less), since the particle size is too small, improvement in wear resistance is difficult to achieve. By increasing the amount added, durability can be improved. However, simply increasing the amount causes an increase in residual potential, resulting in degradation of image quality.
[0050]
An inorganic fine particle (hydrophobic) having an average particle diameter of 0.05 to 0.5 μm is formed on 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 to 2 μm. It is described that the treated silica is dispersed over a thickness of 0.05 to 15 μm (see, for example, Patent Document 15).
[0051]
[Patent Document 15]
Japanese Patent Application Laid-Open No. 08-248663 (summary of the first line to the last line in the lower left column of the first page)
[0052]
In this means, the dispersed silica particles are hydrophobized to prevent the deterioration of the resolution and image flow caused by adhesion of contaminants such as corona products.
Hydrophobization of the inorganic fine particles produces a water droplet repelling effect (a large contact angle), but it cannot prevent the corona product from adhering, and therefore cannot prevent image flow. In addition, the inorganic fine particles treated with hydrophobic treatment on the surface of the photosensitive layer are scraped off by rubbing with a blade and the like, and the resistance of silica is reduced by the action of ozone. Impossible.
[0053]
3. Cleaning device (cleaning brush and cleaning blade)
Cleaning devices include a cleaning brush, a cleaning blade alone, or a combination of a cleaning brush and a cleaning blade. Each has its advantages and disadvantages, and can be selected according to the developer, photoconductor, copy amount, etc. used.
Cleaning brushes are mainly classified into straight hairs (see, for example, Patent Documents 16, 17, 18, and 19) and loops (see, for example, Patent Documents 20 and 21). A type using a combination of a straight hair shape and a loop shape (for example, see Patent Document 22) has also been proposed.
[0054]
[Patent Document 16]
Japanese Patent Laid-Open No. 7-155222 (Claim 2 on page 2, column 1, lines 1-8), FIGS. 1 and 3)
[Patent Document 17]
Japanese Patent Laid-Open No. 6-236134 (second page, first column, lines 2 to 13 in claim 1, FIG. 4)
[Patent Document 18]
Japanese Patent Laid-Open No. 9-22155 (FIG. 1)
[Patent Document 19]
JP-A-11-167224 (FIG. 5)
[Patent Document 20]
Japanese Patent No. 2793647 (1st page, 1st column, 1st line to 13th line, claim, FIG. 3)
[Patent Document 21]
Japanese Patent No. 2619424 (Claim 1 on page 1, column 1, lines 1 to 7 of the claims, FIG. 3)
[Patent Document 22]
Japanese Patent No. 2868539 (1st page, 1st column, 2nd line to 13th line, claim 1, FIG. 4)
[0055]
Each of the brush shapes has some function of removing foreign matters such as toner and paper dust that are difficult to remove with a blade on the photosensitive member, but it cannot remove foreign matters that are firmly fixed like filming. For the material of the brush, nylon-based, polyester-based, acrylic fiber, carbon fiber, or the like is used. A straight brush has a problem of falling down, and there is a problem that the cleaning performance deteriorates as it is used. In a loop brush, cleaning is better than straight hair. There is a problem that the cleaning deteriorates due to clogging. The combined use of the cleaning brush and the cleaning blade is an effective means for enhancing 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 the reverse rotation direction (counter) or the forward rotation direction (leading) with respect to the rotation direction of the photosensitive member.
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 used in most image forming apparatuses. In the blade cleaning method, when the blade is installed in the counter direction with respect to the rotation direction of the photoconductor, the biting into the photoconductor is increased and the toner cleaning performance can be improved.
[0057]
The cleaning blade has a rebound elastic modulus 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). JIS-A hardness of 50 to 90 degrees (see Patent Document 24), JIS-A hardness of 50 to 80 degrees (see Patent Document 25), etc., cut into 1 to 5 mm width (sheet shape) ) A rubber blade is used by being attached to a plate-like support base made of aluminum or iron.
[0058]
[Patent Document 23]
Japanese Patent Application Laid-Open No. 08-248851 (Claim 2 on page 2, column 1, lines 2 to 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 employed as a blade material for cleaning residual powder such as toner has high durability and extremely good adhesion to the organic photoreceptor, and therefore has high cleaning performance. However, since the adhesiveness is high, the frictional resistance with the photosensitive member is increased, and the photosensitive layer is easily worn. Further, when the contact portion of the blade is dragged in the rotation direction of the photosensitive member, the blade is twisted, and the twist continues constantly, the restoration is not sufficient. On the other hand, when dragged sufficiently, a gap is formed, so that resistance is reduced and the original position is repeated, so-called stick-slip phenomenon occurs.
When the stick-slip phenomenon occurs, there is a slight gap when the blade goes back and returns, and toner escapes from the gap, but when it always occurs at the same position, the blade deforms and becomes permanent toner removal, In the part which slipped out, it becomes a streaky filming.
In order to clean the toner well, the edge of the cleaning blade should not vibrate due to rotation, the edge of the blade should not be dragged by the photoreceptor, and the toner may be pressed by the blade. It is important not to make room (the blade should be in line contact with the photosensitive member as much as possible rather than in surface contact during driving).
[0060]
4). toner
In an image forming apparatus, a one-component developer or a two-component developer containing an appropriate amount of toner and carrier is used to visualize an electrostatic latent image formed by charging and image exposure. . Development methods include a magnet brush development method, a spray development method, a cascade development method, and a flying development method, and the mainstream is a magnet brush development method.
As a carrier used for a two-component developer, a resin-coated magnetic powder of about 30 to 80 μm containing a charge control agent such as iron powder, ferrite or magnetite is used. The smaller the particle size, the easier it is to obtain high resolution. However, if the particle size is too small, the electrostatic force of the photoconductor is superior to the magnetic field of the developing device, and the carrier tends to adhere to the photoconductor. May interfere with image loss and cause damage to the photoreceptor.
Therefore, it is necessary to select a carrier suitable for the copying system.
On the other hand, in recent years, with the widespread use of full-color copying machines (image forming apparatuses such as electrophotographic copying machines and printers), higher definition and image reproducibility have been increasingly demanded, and the average particle size has increased. However, a pulverized toner having a sphericity of 4 to 8 μm is used. In recent years, a polymer toner having a high sphericity has been used due to a further demand for high image quality. Since the particle size distribution is as large as ± 3 to 4 μm for the pulverized toner, there are many fine particles of about 1 to 2 μm, which is disadvantageous in terms of S / N, transferability, sharpness, etc., but cleaning properties are relatively good It is. However, when a large amount of fine particles are contained, there is a problem that the fine particles cause toner removal depending on the surface roughness of the photoreceptor. On the other hand, the polymerized toner has a small particle size of about ± 0.5 to 1 μm and is relatively uniform, 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 a mass obtained by melting and kneading additives such as a colorant and a charge control agent in a binder polymer produced by polymerization is coarsely pulverized, finely pulverized, and classified with a sieve. The pulverization method has an advantage that the toner can be finely divided. However, since the process is complicated, the cost tends to increase.
The toner produced by the pulverization method has irregular shapes with irregular shapes. In order to obtain a toner for developer, a step of rounding the corners is further added, and the particle diameter is sieved by classification. In a commonly used toner, since the circularity of the toner is as small as 0.91 to 0.94 (angular), the particles are hardly charged uniformly, and transfer defects are likely to occur. In addition, there is a tendency that scratches tend to occur when pressed against the photosensitive member with a cleaning blade.
In addition, even if a high resolution with good sharpness is obtained at the initial stage, it is difficult to sustain, and when a copy of a copy (second generation, third generation copy) is printed, the resolution becomes extremely poor and not usable for practical use. There is a point. For this reason, a toner having a higher sphericity has been developed, but since the cost is further increased, a conversion to a polymerization method is being promoted.
[0062]
The main production methods of the polymerization method include suspension polymerization method and emulsion polymerization method. For example, in the case of suspension polymerization, the binder resin is produced by homogenizing an additive such as a colorant or a charge control agent, and adding a dispersion medium and a dispersant to polymerize the binder resin. Since the process of the polymerization method is simplified, the manufacturing cost is lower than that of the pulverization method. In addition, there is a merit that the particle diameters are relatively well aligned, 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 the particle diameters are relatively uniform. Therefore, it is easy to uniformly charge and adhere to the 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 toner produced by a polymerization method having many merits is used.
[0063]
Since the spherical toner produced by the polymerization method has a roundness of 0.96 to 1.0, which is almost spherical to spherical, it tends to sink under the blade, and the blade cleaning method tends to cause poor cleaning.
Conventional cleaning blades that have been used with pulverized toner so far use relatively soft rubber blades with a blade hardness of about 60 to 80 degrees. At the same time, the blade edge is also distorted. Further, since the coefficient of friction of the photosensitive member is high, the tip of the blade is caught in the photosensitive member and deformed. For this reason, a slight gap is formed between the blade and the photosensitive member so that the toner is removed, and the toner staying on the cleaning blade is discharged through the gap between the blades. This is especially true when the surface roughness of the photoreceptor is increased due to scratching or filming.
This toner omission tends to be more severe as spherical toner with less circularity and greater circularity.
In a cleaning device in which the contact pressure of the blade is set lightly, there is a case where the cleaning is hardly performed, and the cleaning performance becomes harder to be performed as the photosensitive surface layer is softer.
[0064]
[Problems to be solved by the invention]
Accordingly, the object of the present invention is to start from the twist of the blade edge due to the surface state of the photoconductor, the high friction coefficient of the photoconductor surface, etc., and the magnitude of the photoconductor surface roughness, toner particle morphology, corona product, and Image forming apparatus, image forming method, and process cartridge capable of preventing filming caused by the action of residual powder (paper powder, toner composition, etc.) and maintaining image quality with good S / N and resolution Is to provide.
[0065]
[Means for Solving the Problems]
A spherical toner having a high average circularity, particularly a spherical toner having a high circularity of 0.98 to 1.0, tends to cause poor cleaning because the toner tends to sink under the blade in a cleaning blade designed for pulverized toner. On the other hand, in the case of the pulverized toner, a toner having a small particle diameter of about 1 to 2 μm mixed in the pulverized toner of about 4 to 6 μm is formed by a slight gap of 2 to 3 μm or less generated between the blade and the photosensitive member, When the surface roughness of the photosensitive member is larger than the toner diameter, the photosensitive member enters under the blade and passes through.
When such a slip-through phenomenon is constantly continued, corona products, paper dust, and the like are mixed together, and the photoconductor gradually forms filming, and as it progresses, image quality gradually deteriorates.
[0066]
In order to avoid the filming phenomenon, it is necessary to make the toner slip through zero, but in reality it is quite difficult. For example, if there is a high level of friction coefficient locally on the surface of the photoconductor (due to adherence of corona products, toner components, binder resin of the transfer object, etc.), the blade edge is distorted at that site and the toner is missing. Is likely to occur. Even if there is no toner removal from the blade, if there is even a slight scattering of toner from the developing sleeve, the toner adhering to the photoreceptor causes a filming factor.
Therefore, as a result of intensive studies on means for solving this filming, it has been found that the above-mentioned problem can be achieved by taking the following method.
[0067]
By setting the surface roughness of the photoreceptor surface layer to be smaller than the minimum particle diameter of the toner, the toner is prevented from coming out naturally. Further, by applying a lubricant to the surface layer of the photosensitive layer (performed by means of external addition method or internal addition method), formation and enlargement of irregularities on the surface layer of the photosensitive layer are prevented. By reducing the friction coefficient with a lubricant and adding the filler, the abrasion resistance of the photosensitive layer is prevented so as not to cause excessive abrasion. Further, the friction coefficient due to the lubricant is reduced, the adhesion force of the toner to the photosensitive layer is reduced, and the cleaning property is improved. In addition, the cleaning device consisting of a cleaning brush with improved mechanical strength and a cleaning blade cleans the residual powder on the photoconductor and removes foreign matter adhering by polishing the surface of the photoconductor to the minimum necessary. The filming on the surface of the photoreceptor is prevented.
By these measures, no foreign matter adheres to the surface of the photoreceptor and there is no friction coefficient, so that the surface of the photoreceptor is always kept clean.
Accordingly, it is possible to avoid deterioration of electrophotographic characteristics such as image flow, resolution reduction and charging characteristics, and to provide stable image quality with good S / N until the life of the photoreceptor.
[0068]
That is, the above-mentioned problem is (1) of the present invention, “Applying a voltage to a charging member constituting a charging device disposed so as to face the electrophotographic photosensitive member to uniformly charge the electrophotographic photosensitive member, An electrostatic latent image is formed by optical writing from an image exposure device, 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 cleaned by a cleaning brush and a cleaning blade. In the image forming apparatus using the indirect electrophotographic method, in which the residual powder on the photosensitive member is cleaned using the cleaning device configured, the cleaning brush includes polyester fiber, nylon fiber, acrylic A loop brush composed of any one of the fibers is fixed on the core metal, and the cleaning brush Be those on the surface and internal direction in contact with the optical member resin is applied, together with the cleaning brush is installed in a cleaning device to evenly surface contact with said electrophotographic photosensitive member, the initial and A4 size paper 10-point average roughness Rz after printing 50,000 sheets _JIS Is applied to the surface of the electrophotographic photosensitive member having a maximum height Rz of 0.4 to 1.5 μm, and the cleaning brush and the cleaning blade are simultaneously operated. By (in terms of φ30mm electrophotographic photoreceptor) A4 size paper An image forming apparatus characterized in that an image is formed by maintaining an average wear amount (t) of the photosensitive layer per 10,000 sheets within a range of 0.1 μm ≦ t ≦ 0.5 μm ”, (2) the loop brush The means for fixing on the metal core is a loop brush that is cut into a strip shape and wound and fixed on the metal core in a spiral shape without a gap, and the cleaning brush is disposed on the front side of the cleaning blade with the electronic brush. The image forming apparatus according to the item (1), which is disposed in the cleaning device so as to be in surface contact with the photographic photosensitive member evenly, and (3) “contact with the photosensitive member of the cleaning brush” The image forming apparatus according to the item (2), wherein the resin is applied in the surface and the inner direction by a dipping method ", (4)" Flicker on the cleaning brush " The image forming apparatus according to any one of (1) to (3) above, wherein the bar is not attached, and (5) rotation of the electrophotographic photosensitive member is the cleaning brush. The image formation according to any one of (1) to (4), wherein residual powder on the electrophotographic photosensitive member is cleaned by rotating in a forward direction and rubbing. (Apparatus), (6) "The photosensitive layer constituting the electrophotographic photosensitive member comprises 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. An inorganic filler having an average particle size of 0.3 to 0.7 μm is composed of a dispersed charge transport layer, and the inorganic filler has an average particle size of 0.3 to 0.7 μm. Contains The image forming apparatus according to any one of Items (1) to (5), (7) “Lubrication of zinc stearate or polytetrafluoroethylene (PTFE)” By applying the agent directly to the surface layer of the electrophotographic photosensitive member using an indirect coating means, the friction coefficient is reduced, and an Euler belt method (with a thickness of 85 μm cut to a width of 30 mm and a length of 290 mm). The above-mentioned items (1) to (6) are characterized in that the static friction coefficient measured with high-quality paper (Ricoh Co., Ltd., type 6200 paper, using vertical mesh) is 0.20 to 0.45 at the time of image formation. (8) “Charging at the time of forming an electrostatic latent image on the electrophotographic photosensitive member is performed by surface contact with a charging member having a nip on the electrophotographic photosensitive member. thing The image forming apparatus according to any one of Items (1) to (7), (9) “Charging at the time of forming an electrostatic latent image on the electrophotographic photosensitive member is a charging member and an electron. The image forming apparatus according to any one of (1) to (7), wherein the photographic photosensitive member is kept in a non-contact state with a separation of 30 to 100 μm. 10) “Cleaning device composed of electrophotographic photosensitive member, charging device, cleaning blade and cleaning brush used in the image forming apparatus according to any one of (1) to (9), lubricant application In the image forming apparatus according to any one of (1) to (9), the image forming method by indirect electrophotography, wherein the image is formed by using the means. Electrophotographic photoreceptor used, charging device And a developing device, a cleaning device comprising a cleaning brush and a cleaning blade, and at least one unit selected from a lubricant applying member is integrally supported and is detachable from the main body of the image forming apparatus. Solved by "cartridge".
[0069]
DETAILED DESCRIPTION OF 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 diagram of a copying apparatus using a single color toner in which one developing device is combined with one photosensitive member. The charging means of the photosensitive member is a contact by a charging member using a roller, or a non-contact charging method. It is shown in the figure. 2 shows a lubricant application device (200) ((201) indicates a lubricant and (202) indicates an application brush) for applying a lubricant to the surface layer of the photoreceptor shown in FIG. 1, and between the cleaning device and the charging device. It is the figure attached to.
Although not shown, the photosensitive member can incorporate a vibration damping member for suppressing vibration noise (high-frequency sound) generated when an AC voltage is superimposed on the charging device.
[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 exposure 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 then a photosensitive layer are formed on a drum-like conductive support, and the photosensitive layer further comprises a charge generation layer and a charge transport layer. .
In the charge generation layer, sufficient electron and hole pairs are generated by the 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 that prevents holes from jumping over the interface between the charge generation layer and the charge transport layer when moving toward the negative charge of the surface layer, it is known regardless of whether it is inorganic or organic. The materials can be used.
[0071]
On the other hand, the charge transport layer of the photoreceptor used in the present invention is composed of a filler non-dispersed charge transport layer in which no filler is dispersed and a total weight of a layer in which 0.3 to 0.7 μm α-alumina is dispersed in the filler. It is composed of two layers of an inorganic filler-dispersed charge transport layer in which 20 wt% or more and 35 wt% or less are dispersed.
The reason for dispersing the filler is to improve the abrasion resistance of the photosensitive member and to reduce the biting of the cleaning blade into the photosensitive layer and reduce the edge distortion of the blade. The charge transporting layer has a two-layer structure. This is because the wear resistance is achieved, the accumulation of residual potential, the diffusion of light, and the obstacle of charge transfer are eliminated, and image deterioration is not caused.
The filler dispersed in the filler-dispersed charge transport layer has high hardness, uniform grain, low hygroscopicity, and 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 become rougher and larger as the particle size of the filler increases.
Further, copying also tends to roughen the surface and increase the surface roughness. Therefore, in order not to cause a cleaning failure, it is important to manage the surface roughness so as not to become rougher and larger than the toner particle diameter. Roughness of the surface roughness is considered to be caused mainly by the accumulation of toner in the developer, hard foreign matter such as carrier, talc and resin in paper powder, metal powder other than the above, and the like below the cleaning blade. . Specifically, 10-point average roughness Rz including time _jis Is 0.3 to 1.0 μm, and the maximum height Rz is preferably 0.4 to 1.5 μm.
This is because the surface of the photoreceptor is rough (for example, scratches caused by filler, toner, paper powder, carrier, etc. added to the photoreceptor) and the blade is lifted, and toner loss is prevented from occurring through the lifted portion. is there. Moreover, it is for reducing as much as possible that the contaminants like a corona product enter into the dent between the peaks and are not easily removed by the blade. In the present invention, as shown in FIG. 2 as an example, the lubricant is applied to the surface of the photoreceptor by the external addition method. When the lubricant first enters the dent, the corona product enters the dent. Can be avoided. The means for applying the lubricant to the photoreceptor is a method of applying using a specific apparatus as shown in FIG. 2, a method of applying the lubricant by adding the lubricant to the toner, or several% to several lubricants on the surface of the photoreceptor. There is a method of adding 10% internally.
[0072]
The reason why image formation is performed by applying a lubricant is to reduce the friction coefficient of the photosensitive layer, thereby making it difficult for the blade to be twisted. Second, the photosensitive layer is more than necessary. This is to suppress wear, and thirdly, to reduce the adhesion of toner to the photoconductor so that the cleaning property can be improved.
Fourthly, the dent is filled with a small amount of lubricant so that toner does not slip through. Fifth, in order to reduce the room for the corona product to enter and to avoid deterioration in image quality. It is.
[0073]
By applying a small amount of a lubricant for reducing the friction coefficient to the surface of the photoreceptor, the distortion of the blade edge is alleviated and the toner omission can be improved. Further, since the adhesion force of the toner to the photoreceptor is relaxed, 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 strong) affects the image quality, but application of a small amount of lubricant does not affect the charging characteristics and image characteristics. .
[0074]
In order to form an image, the photoreceptor (1) is charged by the charging device (2). In order to obtain good image forming properties, it is desirable that the contrast potential is at least 250 V or more. For this purpose, the charging potential is preferably -400 V to -800 V.
Although FIG. 1 illustrates an example of a charging roller as a charging member, a charging member such as a brush or a blade may be used in addition to that. There are two types of charging methods, a contact charging method and a non-contact charging method. In the present invention, either method can be used.
[0075]
In the non-contact charging method in which a small gap is charged between the charging member and the photosensitive member, the gap between the charging member and the photosensitive member 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 photosensitive member, it is difficult to reduce the wear caused by the charging member, and when there is toner missing from the cleaning blade, the charging member is less contaminated with toner and has a margin for discharge breakdown. to be born.
The contact charging method has less margin for toner contamination and discharge destruction of the charging member than the non-contact charging method, but since the gap is 0 μm, the applied voltage can be set lower, so that the corona product There is an advantage that the generation amount is reduced.
A high voltage power source is connected to the charging member, and a DC voltage or a DC voltage superimposed with an AC voltage is applied. Both contact charging and non-contact charging are performed according to Paschen's law, and the charging start voltage Vth is the lowest during 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 -1000 V to -2000 V for DC voltage driving, and DC voltage driving for superimposing AC voltage is DC. 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 reason why the direct current voltage superimposed with the alternating current voltage is applied is to prevent uneven charging when there is a gap between the photosensitive member and the charging member, and to prevent image unevenness. Is set to a DC voltage obtained by superimposing an alternating voltage of a Peak to Peak voltage that is equal to or slightly higher than that of the charging start voltage Vth.
[0076]
The roller charging member is covered with an elastic member using a SUS round bar of φ5 to φ15 mm as a core metal. To the elastic member that charges the photoconductor, a resistance control material such as conductive carbon, carbon fiber powder, or ionic conductive agent is added to hydrin rubber alone or urethane rubber or hydrin rubber, and if necessary, repellent properties such as fluorine resin are added. Add a liquid agent to give a specific resistance of 10 ⁵ -10 ¹⁴ Those adjusted to Ω · cm are used. Specifically, the electric resistance of the surface facing the photoconductor between the contact charging member and the non-contact charging member can be changed depending on the charging method.
[0077]
In the non-contact charging member, the outermost surface is 10 ⁵ -10 ⁸ Ω · cm, 10 for contact charging members ¹² -10 ¹⁴ It is set to Ω · cm. This is because there is a gap between the charging member and the photosensitive member, so that the charging start voltage Vth shifts to the higher side and the charging property is different. Therefore, in order to perform uniform charging, the volume resistance of the charging member needs to be low. There is. However, if it is too low, it will cause discharge breakdown. ⁵ It is desirable that it is Ω · cm or more.
Furthermore, the surface roughness of the charging member is 10 point average roughness Rz compared to the contact charging member. _jis It is advantageous to increase the uniform charging and charging efficiency by setting the thickness to about 50 to 200 μm. The hardness is an elastic member having a JIS-A hardness of about 30 to 90 degrees.
[0078]
In the case of the contact charging method, a larger nip (1 to 5 mm) is desirable in order to increase charging efficiency. Therefore, an elastic member having low hardness is used for the contact charging member, but in the case of a non-contact charging member, the nip is used. However, there is an advantage that it 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 photoconductor (1) receives an original image read by a CCD (charge coupled device) or a digital signal transmitted from a personal computer or the like, one or a plurality of LD (Laser Diode) elements, or An image exposure device (3) composed of an LED (Laser Emitting Diode) array, a convex lens, a polygon mirror, a cylindrical lens, etc. irradiates a single-wavelength light image with a dot diameter of about 60 to 20 μm, and receives an input signal. An electrostatic latent image corresponding to the above is formed. For the LD element or the LED array, an element having an oscillation wavelength at or near the highest sensitivity region of the photoreceptor 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 when obtaining a high resolution such as 1200 or 2400 dpi. It can be used by being mounted on a forming apparatus.
[0080]
In order 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.
The carrier of the two-component developer includes, for example, polyfluorinated carbon, polyvinyl chloride to improve the charging property, charging stability, durability, etc. to magnetic powder (magnetic powder) such as iron, ferrite and nickel. Those coated with a resin such as polyvinylidene chloride are used. The particle size of the carrier is about 30 to 60 μm.
The carrier particle size affects the resolution, and a smaller value tends to improve the resolution. However, if the carrier particle size is too small, the carrier is attracted by the electrostatic force of the photoconductor and tends to adhere to the photoconductor. Therefore, if a toner image transfer failure (transfer omission) occurs or is transported to the cleaning section, the blade is pressed against the photoconductor, resulting in damage to the photoconductor surface, increasing the surface roughness, reducing image quality, and unevenness. The corona product enters this portion, causing an image flow and also contributing to shortening the durability of the photoreceptor.
[0081]
On the other hand, the toner is a toner produced by the above-mentioned pulverization method, and a spherical toner manufactured by a polymerization method (emulsion polymerization method, suspension polymerization method, etc.) or a spherical toner manufactured by scraping off an angular region, A toner having an average particle diameter of 4 to 8 μm is used, and 2 to 10 (% by weight) is mixed with the carrier.
The particle size of the toner affects the resolution as well as the carrier, but if it is too small, there is a concern that it will be harmful to the health (environmental destruction = pollution) if it is scattered. Therefore, in the case of pulverized toner, it is desirable to exclude fine particles of about 1 to 2 μm that are crushed as much as possible.
[0082]
When the development is completed, the transfer device (5) is used to apply a voltage having a polarity opposite to the charge held by the toner (a positive voltage for the negatively charged toner), and the toner image on the copy paper (9). Is transcribed.
After the transfer is completed, the copy paper is separated from the photosensitive member (1) by the separation device (6) to which an alternating voltage or a direct current voltage superimposed with the alternating voltage is applied, and is sent to the fixing device (8). It becomes a copy. The separator (6) is generally a corona discharge device that applies an AC voltage or an AC voltage on which a DC voltage is superimposed on a metal wire or a sawtooth electrode. The intensity of the electric field applied to the photoconductor via the copy paper may be such that the copy paper is separated from the photoconductor, so that the amount of corona product generated is small and may be non-uniform, resulting in photoconductor damage. Not as much. When the diameter of the photoconductor is 30 mm or less, the separating device may be omitted depending on the waist of the paper.
[0083]
On the other hand, the residual toner on the photoreceptor after separation of the copy paper is mainly a cleaning brush (7-1) composed of fibers such as polyethylene, nylon, and carbon fiber, and polyurethane rubber, but silicone rubber and 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, the series of copying processes ends, but when applying the lubricant to the photosensitive member (1), for example, the lubricant is applied to the photosensitive member (1) by the means shown in FIG. A lubricant application device (200) shown in FIG. 2 is applied to the cleaned photoreceptor (1) to apply a lubricant. The lubricant application device (200) in FIG. 2 is a system that indirectly applies a lubricant such as zinc stearate or polytetrafluoroethylene to the photoreceptor via a dedicated application brush (202). As other means for applying, the lubricant (201) is applied to the cleaning brush (7-1) to apply the lubricant to the photoreceptor (1), and the lubricant (201) is applied to the photoreceptor (1). In the developer, a lubricant such as zinc stearate, polytetrafluoroethylene, and polyvinylidene fluoride having a particle size of about 0.01 to 0.5 μm is not changed in the toner characteristics (0.01). There is also a method of adding at 0.5 wt%. When it is added to the surface layer of the photoreceptor, no means for applying a lubricant is required.
[0085]
Note that the copying process described with reference to FIGS. 1 and 2 can also 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, four systems (colors) of yellow (Y), magenta (M), cyan (C), and black (Bk) are used on one photoconductor. ) Development device, a one-drum image forming apparatus, as shown in FIG. 3, four photoconductors and four (yellow (Y), magenta (M), cyan (C), and black (Bk). There is a quadruple tandem copying type image forming apparatus using a system (color) developing device.
1 and 2 can be attached to and detached from the main body of the image forming apparatus by combining two or more of the photoconductor, the charging device, the developing device, and the cleaning device composed of the cleaning brush and the cleaning brush. Process cartridge.
For example, 1) a photoconductor and a charging device, and 2) a photoconductor, a cleaning device, and a lubricant application device are examples.
[0086]
Next, the photoconductor will be described.
2. Photoconductor
2-1 Photoconductor outline
The basic structure of the photoreceptor is shown in FIG. The organic photoreceptor is a photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially formed on a drum-shaped aluminum conductive support, and at least an organic material is used for the charge transport layer.
In the present invention, as shown in FIG. 5, the charge transport layer further comprises a filler non-dispersed charge transport layer (ordinary charge transport layer) and a filler-dispersed charge transport layer in which an inorganic filler is dispersed.
A charge transport layer comprising a filler non-dispersed charge transport layer and a filler-dispersed charge transport layer is a layer in which a low molecular charge transport material is dispersed with a binder resin, if necessary, an antioxidant, a dispersant, etc., or a polymer. It is composed of a charge transport material, and the film thickness and layer structure can be set according to the required quality of the photoreceptor.
[0087]
The first purpose of adding a filler (in particular, an inorganic filler made of alumina (α-type) is preferably used in the present invention) is to increase the hardness of the surface of the photoreceptor by adding an appropriate amount of filler. By increasing the wearability, the life of the photoconductor is extended and the image quality is stabilized. However, a significant increase in hardness is a factor that causes image degradation such as image flow in order to reduce wear of the photosensitive layer.
The second purpose is to set a suitable hardness by dispersing a small particle size filler on the surface of the photosensitive layer, to suppress a significant increase in the friction coefficient, and to suppress the penetration of the cleaning blade edge into the layer. This is to reduce the distortion and deformation of the blade edge.
[0088]
The amount of filler added to the charge transport layer is the resolution in initial and time, uniformity of dot pattern, hardness, and surface roughness (10-point average roughness Rz). _JIS , Maximum height Rz, etc.), but when using contact charging or non-contact charging method, filler with 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. It is preferably 20% by weight or more and 35% by weight or less.
It is desirable that the thickness of the photosensitive layer be a thickness that can ensure a sufficient charge level for obtaining a sufficient contrast image and a contrast potential. The contrast potential (difference between the developing bias potential and the image portion potential) for obtaining good image forming properties is desirably at least 250 V or more.
The film thickness for securing the contrast potential of 250 V or more is preferably at least the total film thickness of the photosensitive layer is 10 μm or more. If the film thickness is reduced to 10 μm or less, a sufficient charge level cannot be secured, and it is difficult to obtain a sufficient contrast potential. Further, uneven film thickness of the photosensitive layer is likely to appear in the image, resulting in non-uniform image quality. On the other hand, if it becomes too thick, the dot pattern spreads in the layer, sharpness decreases and resolution decreases, making it difficult to achieve a high-quality image.
Therefore, a preferable photosensitive layer thickness t is 10 μm ≦ t ≦ 30 μm.
[0089]
Hereinafter, the function-separated organic photoreceptor used in the present invention will be described.
2-2 Conductive support
First, the conductive support will be described.
Members 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 characteristics, as well as gold, compressed paper, resin, and glass. There is a conductive layer deposited or sputtered with aluminum, platinum, chromium, or the like, or a conductive layer in which fine particles such as carbon or tin are dispersed. Taking into account the fact that it is thin and easy to cut, light, advantageous for regeneration, easy to form a blocking layer, easy to obtain, etc., aluminum, particularly aluminum alloys such as JIS3003, are suitable.
Technologies for processing the surface of aluminum include cutting, honing, blasting, etc. After cutting a drum-shaped aluminum tube to the required length and cutting it to the target outer diameter, super finishing , Surface roughness is 10 point average roughness Rz by mirror finish etc. _JIS And is sufficiently washed until the cleaning solution is completely removed, and used as a conductive support for an electrophotographic photosensitive member. 10-point average roughness Rz of support _JIS In general, if the thickness is 10 μm or less, abnormal images due to the surface roughness of the support can be suppressed to a level that does not cause a problem in practice.
The shape of the conductive support is preferably a drum shape, and the outer diameter is generally about φ30 mm to φ100 mm.
The thickness of aluminum is about 0.6 mm to 3 mm for a photoconductor having an outer diameter of φ30 to φ100 mm. However, in the case of an organic photoconductor, the temperature during heat drying is 120 to 160 ° C., and the time is 10 to 60. Since it is about a minute, if it does not deform at this temperature and time, a thinner one is desirable. The merit of making it thin is advantageous in terms of cost, and when the damping member is built in, the damping effect is enhanced. However, if it is thin, it may be deformed when a flange is mounted or when a damping member is built in, and sufficient management is required for the shape and dimensions of these members. That is, when the charging and blade contact with each other due to the deformation of the outer diameter, a slight deviation occurs from these members, which affects the non-uniform charging and 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 as necessary.
The form of the undercoat layer may vary depending on the wavelength region used for the light source. For example, when used in a light source such as an LD element or LED array having an oscillation wavelength in the long wavelength region of 650 to 780 nm, moire due to reflection of light from aluminum is generated, so the 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 described in the specific example of the present invention is not necessarily required. Such a thin film having a thickness of 1 μm or less or a semiconductor film that prevents hole injection may be used.
[0091]
The reason for forming the undercoat layer is to prevent charge injection from the support side, stabilize charging characteristics, improve adhesion, prevent moire, improve coatability of the upper layer, reduce residual potential, etc. With the goal. Therefore, a method may be employed in which a semiconductor film that prevents injection of holes and allows electrons to pass therethrough is formed, and an intermediate layer or an undercoat layer is further formed thereon. In general, the undercoat layer is formed with a thin film having a resin as a main component and having a resistance high enough to prevent potential attenuation within a unit time. In consideration of applying the photosensitive layer on the undercoat layer using a solvent, it is desirable that the undercoat layer be a resin having high resistance to dissolution in a general organic solvent. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, and epoxy resin. And a curable resin that forms a three-dimensional network structure. Further, fine powders such as metal oxides exemplified by 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 an appropriate solvent and coating method.
[0092]
Furthermore, a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful as the undercoat layer of the present invention.
In addition, as the undercoat layer of the present invention, Al ₂ O ₃ Or an organic material such as polyparaxylylene (trade name of Parylene = Union Carbide), SnO ₂ , TiO ₂ , CeO ₂ 10 provided with an inorganic material such as ¹⁰ -10 ¹³ A thin film having an electrical resistance of the order of Ω · cm can be used satisfactorily. The thickness of the undercoat layer is suitably from 0.1 to 20 μm, 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 mainly composed of a charge generation material (CGM), and a binder resin is used as necessary. As the charge generation substance, there are inorganic materials and organic materials.
Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. As amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms or phosphorous atoms are preferably used.
[0094]
On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton An azo pigment having a fluorenone skeleton, an azo pigment having an oxadiazole skeleton, an azo pigment having a bis-stilbene skeleton, an azo pigment having a distyryl oxadiazol skeleton, an azo pigment having a distyrylcarbazole skeleton, Perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Njigoido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.
[0095]
The binder resin used as necessary for the charge generation layer includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-. Vinyl carbazole, polyacrylamide, etc. are used. These binder resins can be used alone or as a mixture of two or more. Moreover, you may add a low molecular charge transport material as needed.
[0096]
Examples of the electron transporting material include chloroanil, bromanyl, 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-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more.
[0097]
Examples of the hole transporting material include the electron donating materials shown below and are used favorably.
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 transport materials can be used alone or as a mixture of two or more.
The charge generation layer is mainly composed of a charge generation material, a solvent, and a binder resin, and may contain any additive such as a sensitizer, a dispersant, a surfactant, and silicone oil. good.
[0098]
Methods for forming the charge generation layer include a vacuum thin film preparation method and a casting method from a solution dispersion system. As the former method, a vacuum vapor deposition 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-described inorganic materials and organic materials can be satisfactorily formed. Further, in order to provide a charge generation layer by a casting method, a ball mill, an attritor, or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone together with a binder resin, if necessary, the inorganic or organic charge generation material described above. It can be formed by dispersing with a sand mill or the like and applying the solution after diluting the dispersion appropriately. The coating can be performed using 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, 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 thin, poor sensitivity occurs, but if it is too thick, light attenuation deterioration due to space charge and a residual potential increase occur, leading to 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 ensure a surface potential necessary for image formation. The charge transport layer can of course be used alone as 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 (filler non-dispersed charge transport layer) has a higher hardness. A filler-dispersed charge transport layer to which an appropriate amount of the inorganic filler ultrafine particles is added can be formed. In the present invention, as shown in FIG. 5, the charge transport layer is composed of a filler non-dispersed charge transport layer and a filler-dispersed charge transport layer, and is configured such that there is no clear interface between both charge transport layers. By avoiding the formation of a clear interface, most of the hole-electron pairs generated by image exposure that move toward the surface layer are not captured near the interface, but move to the surface layer and become charged. It is possible to cancel the charge applied in step 1 without any time loss.
That is, since the optical attenuation characteristics hardly deteriorate, high-definition image quality can be reproduced.
However, since the filler is dispersed, some loss due to the amount of filler dispersed, particle size, etc., for example, dispersion in light diffusion and charge distribution occurs, but it is negligible when added in a suitable range There is no practical problem.
[0100]
When an interface is formed between both charge transport layers, the movement of holes is limited, so that the light attenuation characteristic is deteriorated and the residual potential is increased, and the contrast potential is lowered and an afterimage is likely to occur.
The coating means for not forming the interface can be produced by a spray coating method when the thickness of the charge transport layer is as thin as about 10 μm, and the filler non-dispersed charge transport layer can be formed on one of the two spray guns. Put the liquid on the other side, put the filler-dispersed charge transport layer liquid on the other side, apply the filler non-dispersed charge transport layer on the charge generation layer first, allow finger touch drying time (several minutes), then continue the filler dispersion A charge transport layer may be applied. When the charge transport layer is as thick as 25 μm or 30 μm and the filler non-dispersed charge transport layer is as thick as 20 μm, the filler non-dispersed charge transport layer is first formed, touch-dried, and further heated at 120 to 130 ° C. Thereafter, a filler-dispersed charge transport layer is formed within a relatively short time, and the entire photoconductor is heat-dried at a temperature of 130 to 160 ° C. for about 10 to 60 minutes, whereby a photoconductor can be produced.
[0101]
Charge transport layer (filler non-dispersed charge transport layer + filler-dispersed charge transport layer) requires a mixture or copolymer of a charge transport component and a binder component as main components dissolved or dispersed in an appropriate solvent and then required. It can be formed by applying and drying so as to obtain a desired thickness.
The film thickness of the charge transport layer is set to 10 to 30 μm. However, the thinner the variation (difference between the maximum film thickness and the minimum film thickness) of the entire photosensitive layer, the more easily the influence of coating unevenness occurs. Desirably, it is preferably set within a range of ± 1 μm for 10 μm and ± 2 μm for 30 μm.
As the thickness of the charge transport layer decreases, the capacitance increases, so the electric field strength increases, but it is difficult to ensure a high charge level. If the charge possessed by the toner is small, it is possible to increase the developing ability even with a thin film photoconductor, but it is unavoidable to use voltage development with a small particle size toner that is currently used in the market. For this reason, a certain surface potential is required.
[0102]
If the film thickness of the photosensitive layer is reduced, the distortion of charge transfer is reduced, so that a high-quality image can be reproduced. On the other hand, as the thickness is increased, the electrostatic capacity is reduced, so that a high charge level can be ensured. However, when the charge moves, it tends to be distorted when light is input and the resolution tends to decrease. When the film thickness of the photosensitive layer is about 10 μm, the charging level is charged only at around −450V. However, if the residual potential is suppressed to about -50V to -100V and the developing bias potential is set to -350V, the contrast potential can be secured to about 250V to 300V, so that it is possible to perform image formation with no practical problem. .
[0103]
The charge transport layer is formed on the charge generation layer in the order of a filler non-dispersed charge transport layer and a filler dispersed charge transport layer. This is because when the filler-dispersed charge transport layer is in direct contact with the charge generation layer, an abnormal movement of charge occurs between the filler-dispersed charge transport layer and the charge generation layer, and a spotted pattern appears in the image. Accordingly, it is desirable that the charge transport layer does not disperse the filler in the region in contact with the charge generation layer, and the film thickness is desirably at least 2 μm.
As 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, optical transparency, and electrical resistance of 10 ¹⁰ It is desirable that it is Ω · cm or more. Preferably 10 ¹² Ω · cm to 10 ¹⁴ Ω · cm. If the specific resistance is low, it will be difficult to hold the charge, and if the resolution is low or the specific resistance is too high, the residual potential will increase, the image area potential will increase, the contrast potential will decrease, and sufficient image density will not be obtained. , The image becomes uneven.
The filler in the filler-dispersed charge transport layer is preferably either uniformly dispersed in the charge transport layer or a layer configuration with a concentration gradient 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 is affected by the required durability (depending on wear, chemical and physical degradation), and image quality (charging level, sensitivity, residual potential, etc.) 20 wt% to 35 wt% of the total weight of the filler-dispersed charge transport layer is desirable. If it is 20% by weight or less, the wear increases rapidly, and if it is 35% by weight or more, the residual potential increases, the surface roughness of the photosensitive layer deteriorates, and the surface roughness increases. Therefore, the toner is likely to be removed, and from the formation of toner filming to the image flow.
[0105]
The film thickness of the filler-dispersed charge transport layer needs to be changed 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 is increased, the optical characteristics and electrical characteristics are deteriorated, resulting in a decrease in resolution and an increase in residual potential, resulting in a decrease in image quality. Therefore, it is necessary to suppress the film thickness within a range in which the required image quality can be maintained. The allowable film thickness when the amount of filler added is in the range of 20 wt% or more and 35 wt% or less is about 8 μm, and if it is usually 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.
As the low-molecular charge transporting material constituting the charge transporting layer, oxazole derivatives, oxadiazole derivatives, imidazoles derivatives, triphenylamine derivatives, α-phenylstilbene derivatives, toniphenylmethane derivatives, anthracene derivatives, and the like can be used.
[0107]
On the other hand, as the polymer charge transport material, the following known polymer charge transport 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 50-82056 A, JP 54-9632 A, JP Examples thereof include compounds described in JP 54-11737 A and JP 4-183719 A.
2) Examples of the polymer having a hydrazone structure in the main chain and / or side chain include 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) Examples of the polymer having a tertiary amine structure in the main chain and / or side chain include N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-13061, Compounds described in Kaihei 1-19049, JP-A-1-1728, JP-A-1-105260, JP-A-2-167335, JP-A-5-66598, and JP-A-5-40350 Etc.
5) Other polymers include, for example, formaldehyde condensation polymers of nitropyrene, compounds described in JP-A Nos. 51-73888 and 56-150749, and the like.
[0108]
The polymer having an electron donating group used in the present invention is not limited to the above polymer, but also a copolymer of known monomers, 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.
Further, as the polymer charge transport 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 polymer 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 copolymers thereof), cellulose acetate resin, ethyl cellulose resin, polyvinyl Thermoplastic or thermal such as butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin 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 the dispersion solvent that can be used in preparing the charge transport layer coating solution include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve, toluene, xylene, and the like. Examples include aromatics, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate, but it is desirable to avoid the use of halogen-based solvents 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. For this reason, when the photosensitive member is repeatedly used, the residual potential accumulates and the image portion potential is increased, so that the image density and the resolution are likely to decrease. Therefore, it is possible to add an additive which improves the dispersibility, makes the photosensitive layer uniform, inhibits trap formation, and reduces trap density.
In addition, the means for applying a charge to the photoconductor in the image formation is performed by a charging device that is in contact with or close to the photoconductor, and corona products such as ozone and nitrogen oxide generated at the time of charging are in the photoconductor. It adheres to the surface layer or enters the photosensitive layer, lowering the electrical resistance and causing image quality deterioration such as resolution reduction. In order to eliminate this, a small amount of an antioxidant and a plasticizer can be added. However, these additives are not always necessary, and may be left unadded when the charge transport layer is thin, when the amount of filler added is small, or depending on the image system.
[0111]
In the charge transport layer to which a filler is added, a coating liquid in which an appropriate amount of filler is dispersed in a binder resin is applied to a target film thickness using a coating method such as a spray method or a dipping method.
10 fillers ¹⁰ -10 ¹⁵ It is desirable that it has a specific resistance of about Ω · cm, have water repellency, and maintain its function. 10 in particular ¹² -10 ¹⁴ Ω · cm.
Filler materials include organic filler materials and inorganic filler materials. Examples of organic filler materials include fluorine resin powders such as polytetrafluoroethylene, silicone resin powders, and amorphous carbon powders. Materials include copper, tin, aluminum, indium and other metal powders, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide and tin. Examples thereof include 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 to improve 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, relatively good translucency, good dispersibility in resin, strong oxide film, and a specific resistance of 10 ¹³ -10 ¹⁵ It is around Ω · cm. Furthermore, since it has water repellency, environmental stability is excellent. Accordingly, 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 material, a binder resin, a solvent, and the like using an appropriate disperser.
When the surface roughness of the photosensitive layer increases due to the addition of the filler, the character edges become jagged, and the cleaning properties of residues such as toner and paper dust are deteriorated, resulting in a problem of defective cleaning. Contaminants such as corona products remain in areas where the blade does not contact, causing image flow, toner filming, and chipping of the edge of the cleaning blade, which can easily damage the photosensitive layer. Therefore, it is necessary to select a filler having a particle size with good dispersibility so that the target wear 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 from the light transmittance, wear resistance, surface roughness, etc. of the charge transport layer.
[0114]
FIGS. 6 to 8 show measurement examples of the filler particle size and addition amount of the filler-dispersed charge transport layer formed on the charge transport layer of the photoreceptor and the surface roughness. The photosensitive layer was 22 μm in the filler non-dispersed charge transport layer, and the film thickness of the filler dispersed charge transport layer was about 5 μm, and was measured using Tokyo Seimitsu's Surfcom Model 1400D.
FIG. 6 shows filler particle size and surface roughness (maximum height Rz, 10-point average roughness Rz) of a filler-dispersed charge transport layer (added amount 25 wt%) formed on an aluminum support having a diameter of 30 mm. _JIS ), FIG. 7 shows the amount of filler added (average particle size 0.3 μm) and surface roughness (maximum height Rz, 10-point average roughness Rz) of a photoconductor having a diameter of 60 mm. _JIS FIG. 8 shows the amount of filler added (average particle size 0.3 μm) and surface roughness (maximum height Rz, 10-point average roughness Rz) of a 30 mm photoreceptor. _JIS ).
[0115]
10-point average roughness Rz _JIS The reason why the maximum height Rz is specified is as follows.
10-point average roughness Rz _JIS 10 point average roughness Rz even if the blade is distorted _JIS And the gap generated by the blade distortion is smaller than the minimum toner, it is possible to prevent the toner from coming off. On the other hand, by defining Rz, it is possible to prevent the toner from having a minimum toner particle diameter when the blade is not distorted (twisted).
That is, in order to prevent the toner from being removed, 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 reduction means using a lubricant for reducing the frictional resistance between the blade and the photoreceptor is indispensable. However, the means for reducing the friction coefficient may be a means for adding a lubricant to the outermost surface layer of the photosensitive member, or a means for changing to a lubricant.
When the filler particle size is 0.5 μm and the addition amount exceeds 30 wt% to 40 wt%, the surface roughness tends to increase suddenly (see FIGS. 7 and 8). When the surface roughness is larger than the minimum particle diameter of the toner, the toner is easily removed, and when the blade is twisted, the toner is further removed.
In addition, the sharpness of the character image due to the surface contamination of the photoreceptor is reduced. The toner omission is determined by the minimum particle diameter of the toner, but when a toner having a weight average particle diameter of 4 μm is used, the frequency of the presence of toner having a minimum particle diameter of about 1 μm is about several percent. Of the roughness, if the maximum height Rz is 1.5 μm or less, toner omission can be almost avoided.
This value is effective not only in the initial stage but also in the durability of the photosensitive member. In other words, in order not to cause toner loss, it is necessary to maintain the value within the above-mentioned value. Also, 10-point average roughness Rz _JIS Is important to maintain good image quality.
10 point average roughness Rz _JIS In addition, the filler particle size and the added amount satisfying the maximum height Rz are about 1.1 μm and about 45% by weight, respectively, but when the electric characteristics such as residual potential and sharpness, and the image quality characteristics are taken into account, the filler dispersed charge The average particle size of the filler added to the transport layer is preferably 0.3 μm or more and 0.7 μm or less, and the addition amount is preferably 20% by weight or more and 35% by weight or less.
As described above, the filler particle size and amount added to the charge transport layer not only affect the surface roughness of the photoreceptor surface, but also have a great influence on the electrical and mechanical properties. is necessary.
In the contact charging or non-contact charging method, the chemical damage to the photoreceptor is large, so it is necessary to increase the wear resistance. The smaller the amount of filler added, the lower the wear resistance. When the amount is 20% by weight or more, the wear resistance gradually improves, and when it is 20% by weight or less, particularly 10% by weight or less, the wear resistance tends to be rapidly increased. is there. Therefore, when using contact charging or non-contact charging, it is desirable to add 20% by weight or more when at least alumina is used.
[0116]
In the charge transport layer according to the present invention, for example, a leveling agent is an effective means for smoothing the surface of the photosensitive layer by eliminating the roughness. A known material can be used as the leveling agent, but a silicone oil-based leveling agent that can impart a high level of smoothness in a small amount and has a small influence 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, amino-modified 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. It is also possible to reduce the unevenness depending on the coating conditions. For example, in dip coating, when the surface of the coating film is still wet after being lifted up, the surface can be covered with a hood so that the surface is not disturbed by the flow of wind, etc. to reduce unevenness. Is done. Also, if the solvent near the coating surface suddenly volatilizes, only the surface hardens and the inside of the coating film becomes fluid, and the coating film inside may sag and form irregularities. In a wet state, a vapor layer of a solvent is formed around the photoconductor, and the solvent is gently volatilized, so that leveling proceeds, and the unevenness is reduced and smoothed.
[0117]
In addition, in spray coating, when forming a coating film by air spray, by controlling the air pressure and air flow to an appropriate amount, surface irregularities can be suppressed while the coating film is in a fluid state. It is necessary to suppress. Here, if the air pressure and air flow rate are too large, the surface of the coating will be disturbed by the air flow, and conversely if it is too small, the coating liquid droplets may not be uniform or atomization may be insufficient. As a result, the uniformity of the coating film is reduced. Further, after the charge transport layer is formed, the solvent is volatilized while rotating, but if the rotation speed at this time is too high, centrifugal force is applied to the coating film that still contains the solvent and has fluidity, and the unevenness is emphasized. On the other hand, if the rotational speed is too low, the influence of dripping due to gravity is superior to the leveling due to rotation, which causes unevenness. For this reason, it is necessary to set the rotation speed of the photoreceptor in a wet state to an appropriate value.
Further, in spray coating, it is important that the liquid feeding of a pump that supplies the coating liquid is constant. That is, if the supply of liquid is not constant but has pulsation, it directly affects the discharge amount of the liquid, resulting in unevenness in the amount of adhesion. Therefore, as the pump for supplying the liquid to the spray, it is preferable to use a multiple plunger pump with suppressed pulsation, a syringe-type ultra-precise discharge device, or the like.
These methods may be used singly, but by combining a plurality of methods, leveling is more effectively performed and a charge transport layer with reduced unevenness is formed.
Further, when leveling is insufficient, it is possible to wear the convex portions of the charge transport layer and wear them as a method for reducing the irregularities. For example, a method of detecting a convex portion with a film thickness meter and polishing the portion to eliminate the convex portion can be considered.
[0118]
In the present invention, for the purpose of improving environmental resistance and preventing the decrease in sensitivity and the increase in residual potential, oxidation is performed on each layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, and an intermediate layer. 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, but are not limited to, the following.
(A) Phenolic compounds
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-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- ( 2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-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] Cricol esters, tocopherols, etc.
(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-t-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) Organophosphorus 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, but are not limited to, the following.
(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, diisononyl 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, etc.
(C) Aromatic carboxylic ester plasticizer
Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.
(D) Aliphatic dibasic acid ester plasticizer
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl-n-decyl adipate, diisodecyl adipate, dicapryl adipate, diazeline 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, glycerol monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
(F) Oxyester 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 epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate and the like.
(H) Dihydric alcohol ester plasticizer
Diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate, etc.
(I) Chlorine-containing plasticizer
Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, etc.
(J) Polyester plasticizer
Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, etc.
(K) Sulfonic acid derivative
P-toluenesulfonamide, O-toluenesulfonamide, P-toluenesulfoneethylamide, O-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, P-toluenesulfone-N-cyclohexylamide and the like.
(L) Citric acid derivative
Triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, acetyl citrate-n-octyldecyl 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 thereof include the following, but are not limited thereto.
(A) Hydrocarbon compounds
Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, etc.
(B) Fatty acid compounds
Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, etc.
(C) Fatty acid amide compounds
Stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide, etc.
(D) Ester compound
Lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, fatty acid polyglycol esters, and the like.
(E) Alcohol compounds
Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol, etc.
(F) Metal soap
Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate, etc.
(G) Natural wax
Carnauba wax, candelilla wax, beeswax, whale wax, ibotarou, montanro, etc.
(H) Other
Silicone compounds, fluorine compounds, etc.
[0122]
Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
(A) Benzophenone series
2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like.
(B) Salsylate type
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′-tertiarybutyl) -5'-methylphenyl) -5-chlorobenzotriazole
(D) Cyanoacrylate type
Ethyl-2-cyano-3,3-diphenyl acrylate, methyl-2-carbomethoxy-3- (paramethoxy) acrylate, and the like.
(E) Quencher (metal complex)
Nickel (2,2′-thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate 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 be in surface contact (contact) with the photosensitive member evenly. The amount of biting into the photoreceptor is preferably 1 to 2 mm. Uneven installation causes uneven wear on the brush as well as the photosensitive layer. 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 photoreceptor). This is because in the counter direction, the photosensitive layer is easily scraped and uneven scraping is likely to occur. Further, the present invention is characterized in that a flicker bar that is generally provided is not provided in order to eliminate toner adhering to the brush. This is because when a flicker bar is attached, in the case of a loop brush, toner removal unevenness is likely to occur, the toner is easily pushed into the fiber, and the fiber is easily damaged. That is, unevenness in the shaving of the photosensitive layer is likely to occur, the shaving of the filming film is likely to become uneven, and further, an image flow may occur in the region of unevenness in removing 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. In the present invention, a loop brush is used.
The material of the loop brush used for cleaning includes nylon fiber, acrylic fiber, polyester fiber, carbon fiber, etc., and fiber manufacturers include Unitika, Toray, Kanebo, Kuraray, and Mitsubishi Rayon.
The fiber diameter of the fibers used in the cleaning brush is 10 to 20 (denier = D = yarn weight (g) × 9000 ÷ yarn length (m)), and the 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 warp and weft fibers of the base fabric. FIG. 10 shows a schematic diagram of the loop brush roller. As for the cleaning brush, a loop brush cut into strips (strings) is wound around the metal core spirally without gaps, and fixed so that there is no displacement. The fixing means may be an adhesive or may be fixed using a double-sided adhesive tape. By adopting such a manufacturing method, it is possible to maintain a stable and uniform cleaning property without deviation. The manufacturing method is simple and can be performed in a short time. If a double-sided adhesive tape is used, the core bar can be reused.
[0126]
The purpose of using the loop brush is that it is less likely to cause rubbing scratches on the photoreceptor as compared to a normal straight hair cut pile brush. In general, a low-hardness photoconductor is rubbed with a cleaning blade, a brush, or a developer, so that the surface of the photoconductor is rubbed to a greater or lesser extent. However, when a cut pile brush is used, it is about 100 to 250 rpm. Because the cut surface of the fiber tip that rotates at the number of rotations hits the photoconductor, scratches (fine scratches) are more likely to occur than with a loop brush, and abnormal images (white spots, black spots) tend to occur over a long period of time. Reduce lifespan. In the case of a loop brush, since it rubs at the belly or back portion of the fiber, there is little occurrence of deep scratches, and in most cases it becomes a shallow uniform rubbing scratch.
Loop brushes that can be suitably used in the present invention include acrylic fibers such as SA-7 (Toray Industries, Inc.), nylon beltlons ([nylon fiber, Kanebo, types 931, 961, etc.), polyester beltrons [polyester fibers]. Fiber, Kanebo, type B31, etc.].
[0127]
The brush is rubbed with the photosensitive member, and triboelectric charging occurs, so that the toner easily adheres, and a phenomenon in which the cleaning property gradually deteriorates is observed. Therefore, it is desirable that the brush be resistance controlled. Conductive treatment is carried out at the fiber manufacturing stage, and a method of filling conductive carbon into the fiber, and when the resin is in a molten state, conductive carbon and fine metal particles such as tin, gold, titanium are put into fiber. The Further, after the fibers are formed, the conductive fibers and the fibers may be mixed.
However, if the resistance is too low, there is a discharge from the photoconductor, causing an abnormal image. ⁵ -10 ¹⁰ A medium to high resistance of about Ω · cm is desirable.
SA-7 and Beltron are both electrically conductive and have a self-discharge capability even when charged. Therefore, even if toner is electrostatically adsorbed, it can be removed from the brush after copying. it can. In the case of Veltron, conductive fine particles such as carbon are incorporated inside, and in SA-7, carbon is dispersed. The tendency for static elimination to be higher in Beltron than in SA-7 is seen. However, it takes several seconds to several tens of seconds for the electric charge to be sufficiently discharged.
When the cleaning brush is used, the brush and a core material (metal, conductive resin, or the like) are electrically coupled, and the core material is grounded (grounded) to the housing, or a voltage is applied. Normally, it is sufficient to ground.
[0128]
In the case of a hard film such as filming, it cannot be completely removed even with a straight hair brush (cut pile brush), and the removal ability is low with a loop brush. Since 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 image quality is deteriorated.
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, a cleaning brush is coated with a resin, and polishing ability is added, so that filming buds formed on the surface of the photoreceptor are surely picked up (polished) every cycle without being worn deeply. This is very important.
The average wear amount t for polishing the photosensitive layer with a cleaning brush is 0.1 ≦ t ≦ 0.5 μm per 10,000 sheets (value converted to φ30 mm photoconductor, in the case of A4 size paper), and the wear amount is 0.1 μm or less. If the number is small, the probability of local image flow due to uneven polishing increases, and an abnormal image may be generated due to the 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 since the wear is large, durability cannot be maintained, and when mass copying is performed, early replacement is unavoidable.
Needless to say, less wear is desirable as long as the image quality can be maintained.
[0129]
Although the means for polishing the photosensitive layer is also shown in the disclosed examples, a method using an abrasive or the like is worn out and is not practically used. The polishing means can be performed more reliably by the brush than by the blade. In order to add 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 reliably polish the filming with a very thin film by a simple method, it is preferable to coat the loop fiber with a resin that increases the polishing effect. As the covering material, 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, or aluminum, an amorphous carbon film, silicon, or the like is coated by a method such as coating with an acrylic, epoxy, or urethane resin, a CVD method, a vacuum deposition method, or a sputtering method. 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, Merci 585 manufactured by Toyo Polymer Co., Ltd.) and an epoxy curing agent (for example, AD-C-65 manufactured by the same company) are used as the main agent. A mold can be suitably used. The coating method may be performed by laying the loop brush on the side, immersing the fiber in a resin solution by 2 to 3 mm so that the solution reaches the inside of the fiber, and heat drying. In the case of the above resin, liquid such as ion exchange water or distilled water is used as a solvent, so there is no concern about pollution.
[0130]
On the other hand, for the cleaning blade, a polyurethane rubber 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), An aluminum or iron support substrate fixed using an adhesive (FIGS. 11 and 13), a portion that contacts the photoconductor does not contact the surface, but a knife-edge shape that makes almost line contact (FIG. 12, 14) and the like can be used.
The blade is a means to completely remove residual powder (toner, paper dust, corona product, filler, dust, etc.) that could not be removed by the cleaning brush, so it 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 photoconductor, and is pressed (contact pressure) so that the amount of biting is about 0.5 to 2 mm. And fixed at an acute angle. The contact angle θ2 of FIG. 13 is 15 to 40 degrees, and the free length L2 of the blade tip is 3 to 8 mm.
When the frictional resistance between the photoconductor and the blade is large, the edge portion in contact with the photoconductor is dragged in the rotation direction of the photoconductor to cause local twisting, and the edge tends to be in line contact from line contact.
For this reason, a slight gap is generated between the photosensitive member and the blade, and the toner is sandwiched between the blade and the photosensitive member, so that toner is lost. In order to prevent this, it is necessary to reduce the coefficient of friction of the photosensitive layer surface by suitable means.
[0131]
The shape of the tip of the blade can maintain good cleaning performance by reducing the friction coefficient of the photosensitive member to around 0.3, even with a sheet cut to 90 degrees in the above-described strip shape. Even in the case of a high value of 0.5 or more, it is effective to make the blade tip part a knife edge as shown in FIG.
In the case of a knife edge shape, it is desirable that the rubber hardness used for the blade is high, and a rubber blade of about 80 to 90 degrees is used. When the hardness is high, the photosensitive layer is easily worn, but the durability of the photosensitive layer is not deteriorated by increasing the hardness of the photosensitive member surface with which the blade contacts with a filler. The angle θ1 at the tip of the knife edge in FIG. 14 may be 90 degrees or less and within a range of 30 degrees, and 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), a metal such as aluminum, phosphor bronze, iron or brass, a resin such as polycarbonate, vinyl chloride, delrin or polyethylene terephthalate, or a ceramic member such as alumina is applied to a plate or casing. A cleaning blade can be attached after processing, but due to its properties such as workability, toughness, no temperature deformation, and no rust, a chrome-plated iron plate or a metal plate with a thickness of about 1 mm to 3 mm such as an aluminum plate Is preferred. The method of attaching the blade by processing the support substrate is a method of fitting and fixing to the casing-like support substrate, bending the metal plate, adhesive (double-sided tape, one-component or two-component adhesive, hot melt There is a method of attaching and fixing using an adhesive or the like.
[0132]
The knife edge-shaped blade processing method shown in FIG. 14 is produced by cutting the tip with a knife or by molding. Polyurethane rubber is mainly composed of polyol, isocyanate, and curing agent. A molding machine in which a dehydrating polyol and isocyanate are mixed and a curing agent is added to a prepolymer obtained by reacting at a temperature of 70 to 140 (° C.) for about 100 minutes and heated to 140 to 160 ° C. in advance. And curing for 50-60 minutes. Then, it is obtained by taking out from a metal mold | die and cutting with a cutter to a required magnitude | size.
Polyurethane rubber used for the cleaning blade is cut at the tip with a cutting machine at an angle, or after cutting into a knife edge with a die, the burrs at the edge that contacts the photoconductor are accurately cut in a straight line to make the thickness of the tip Is adjusted to 0.5 mm or less.
In the mold manufacturing method using this mold, as long as the mold is manufactured, it can be manufactured relatively easily.
[0133]
The contact pressure (linear pressure) when the edge of the blade contacts the photoreceptor is preferably set to 15 g / cm to 40 g / cm. However, in view of cleaning properties, scratches applied to the photoreceptor, etc., 15 g / cm It is preferable to set it to cm or more and 25 g / cm or less. At 15 g / cm or less, when a blade with a high JIS-A hardness is used as the blade, depending on the surface roughness of the photoreceptor, a gap may occur between the cleaning blade and the photoreceptor even if there is a small amount of foreign matter, resulting in poor cleaning. Can happen.
When set higher than 25 g / cm, since the hardness is harder than that of a conventional product, scratches may occur due to blades on the photosensitive member, but even if set to 40 g / cm or higher, scratches will occur. Just because the possibility increases, usually a shallow rubbing scratch does not occur, and it does not mean that it can not be used immediately except when a hard foreign object is stuck in the photoreceptor and the blade edge is scratched.
When the cleaning blade in such a state is used, it is possible to satisfactorily clean even 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 photosensitive member includes a corona charging method, a contact charging method, and a non-contact charging method in which charging is performed while holding a gap of 30 μm or more and 100 μm or less with the photosensitive member. Any charging method can be used. However, since the corona charging method generates a large amount of ozone, it is necessary to perform ozone exhaust treatment sufficiently. If it leaks, there is a health problem as well as odor. A contact or non-contact charging method is preferably used.
Both the contact and non-contact charging methods are charging methods that involve discharge, but due to the low applied voltage, ozone generation is as low as around 0.1 ppm, and even if there is leakage outside the machine, it will decompose in the middle. There is no odor leaking outside. However, since contact charging is a discharge in the vicinity of the photoconductor, chemical damage to the photoconductor may be greater than that of the corona charging method. For this reason, the wear of the photosensitive layer is also affected, and the wear tends to be larger than that of the corona charging method. Therefore, it is essential to take measures against the wear resistance of the photoreceptor.
The shape of the charging member can be broadly divided into three shapes: a roller, a brush, and a blade. In view of durability, uniform charging, image quality, workability, and the like, a roller charging system as shown in FIG. 15 is preferable. .
[0135]
The difference between the contact charging method and the non-contact charging method is that the distance between the contact charging method and the photoconductor is 0 μm, the non-contact charging method is 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. If the gap is 30 μm or more, even if the roundness and straightness of the photosensitive member and the charging member are 20 μm, which is the limit that causes uneven charging, the photosensitive member and the charging member do not come into contact with the photosensitive member and paper. Contamination caused by powder adhesion can be avoided to some extent. In the range of 50 μm or more and 80 μm or less, the developer carrier averages 30 to 60 μm. Therefore, even when one carrier adheres to the photoconductor, the photosensitive layer can be pressed against the photoconductor by the charging roller. Therefore, it means the minimum gap that does not cause discharge breakdown. Also, as the gap becomes larger, the charging uniformity is more easily lost, so the applied voltage and frequency must be increased. Therefore, it is necessary to suppress the upper limit of the gap, but the gap of 80 μm is the minimum gap that can achieve charging uniformity by slightly increasing the electric field condition applied to the charging member.
[0136]
In the contact charging method, a member having a JIS-A hardness of about 30 to 80 degrees is mainly used, but a non-contact charging member has a JIS-A hardness of about 90 degrees or more. Even members can be used. That is, in the case of a non-contact charging member, the surface facing the photoconductor is made of a rubber-like or dense sponge elastic resistor having a thickness of 0.5 to 5 mm, and the other regions are made of metal. It is also possible.
[0137]
The resistance value differs between the contact charging method and the non-contact charging method, and the resistance value of the member used for the contact charging method is set higher. This is because the distance from the photoconductor is 0 μm, so that even if the resistance value is high, charging can be sufficiently performed. Covering the area can be reduced.
Specifically, in the case of the contact charging member, the volume resistance is 10 on the surface facing the photoconductor. ¹² -10 ¹⁴ A high-resistance layer having a thickness of about 1 to 3 mm and having flexibility to earn a nip between the core metal and the high-resistance layer 10 ⁵ -10 ⁹ It consists of a medium resistance layer of Ω · cm. The hardness of the medium resistance layer is 30 to 75 degrees in terms of JIS-A hardness, and the high resistance layer is also about 60 to 80 degrees.
On the other hand, in the case of a non-contact charging member, the resistance layer facing the photosensitive member has 10 ⁵ -10 ⁸ Use an elastic member with medium resistance of Ω · cm. As for the thickness, members other than the cored bar may be members of all layers or medium resistance layers, or members having different hardness and resistance values such as contact charging members may be used. The thickness of the medium resistance layer may be about 1 to 3 mm, and the others may be metal. A charging member having a JIS hardness of 30 to 90 degrees can be used, but a member of 60 to 85 degrees is usually used.
[0138]
The elastic member of the resistance layer is a rubber product such as urethane rubber, hydrin rubber, chloroprene rubber, silicone rubber, fluorine rubber, etc., and resistance control of conductive carbon, activated carbon fiber, metal powder such as tin, gold, titanium, etc., ion conductive agent, etc. Although an appropriate amount of an agent is added, hydrin rubber is used in the present invention. This is because the hydrin rubber can obtain a medium resistance without adding carbon or the like, and since no carbon is added, the electrical resistance is hardly influenced by the environment. 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 to improve the releasability in order to prevent the toner from adhering, and the electric resistance is 100 VDC. 10 when applied ¹² -10 ¹⁴ Set to be in Ω · cm.
[0139]
The surface roughness of the charging member is finer for the contact charging member and rougher for the non-contact charging member. This is to ensure good chargeability, and the 10-point average roughness Rz _JIS The contact charging member is set to 100 μm to 10 μm, and the non-contact charging member is set to 200 to 20 μm.
In the case of the contact charging method, since the distance to the photoconductor is 0 μm, the applied voltage can be set lower because the charging efficiency is higher even if the resistance of the charging member is higher than in the non-contact charging method. For this reason, the generation amounts of ozone and NOx are reduced, and in terms of image quality, abnormal images rarely reach other parts even if there is a pinhole. Therefore, high-quality image formation can be performed.
On the other hand, in the case of the non-contact charging method, the applied voltage becomes high because there is a distance of several tens of μm. Therefore, generation of ozone is 0.2 to 0.4 ppm, which is about three times that of the contact charging method. Because there is almost no amount leaking 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. Therefore, it is advantageous in terms of discharge breakdown and contamination of the charging member, but when a hard foreign material such as metal or electric field strength is high, the same precautions as in the rapid charging method are necessary. Image quality is equivalent to the contact charging method.
[0140]
5). Friction coefficient of photoreceptor and method for reducing the same
Maintaining the coefficient of friction of the surface of the photosensitive layer at a low level is effective for improving the abrasion resistance of the photosensitive layer, improving the transferability of the visualized toner image, and improving the cleaning property with the cleaning blade. That is, the rubbing pressure of the cleaning blade against the photosensitive member is reduced, and the adhesion force of the toner to the photosensitive member is reduced. Therefore, the surface layer of the photoreceptor is less likely to be scratched, and when the toner, carrier, etc. are sufficiently dammed by the cleaning blade, only the cleaning blade is rubbed, and further, the application of the lubricant can reduce the rub. it can.
[0141]
As means for reducing the friction coefficient, an external addition method in which a lubricant is applied to the surface of the photoreceptor (an example in which a lubricant scraped off with a brush is applied to the photoreceptor is shown in FIG. 2), the outermost surface layer of the photosensitive layer is micron. The process is carried out by any of the 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 reduce the surface friction coefficient. When the amount added is small (for example, about 5% of polytetrafluoroethylene is added), the corona product may act on the surface of the photoreceptor and seal off the action of the lubricant, so 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, since the coefficient of friction is maintained due to the abrasion of the photosensitive layer, it is difficult to improve the durability such as 100,000 sheets or 200,000 sheets when added in a large amount, but it is an effective means in that it does not require ancillary equipment. 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 material such as polytetrafluoroethylene, polyvinylidene fluoride, or zinc stearate exhibiting lubricity can be applied directly or indirectly to the surface of the photoreceptor.
As a direct method, a powdery lubricant is incorporated in a bag such as a gauze with a coarse texture, or a sheet-like lubricant is applied while being rubbed against the surface of the photoreceptor, an indirect method. Include a method of applying by dispersing 0.01 to 0.5% in the toner, a method of bringing a lubricant into contact with a cleaning brush, and applying a lubricant powder scraped off by the brush to the photoreceptor. is there.
[0143]
When a lubricant is applied to the photoreceptor, polytetrafluoroethylene can easily reduce the friction coefficient of 0.6 to 0.2 or less. However, generally, if the coefficient of friction is too low, the corona product adhering to the photoconductor will not be scraped off, causing image flow or toner adhering to the corona product film. However, in the present invention, the corona product is removed with a cleaning brush, so that even if it is reduced to about 0.2, it leads to image flow. There is nothing. However, if the friction coefficient is too low, the development is affected, and there is a phenomenon in which characters become thin due to toner sliding. Therefore, it is desirable that the friction coefficient is 0.2 or more, and higher is 0.45 or more. It is desirable not to rise. This is because it affects the durability of the photosensitive member and the twist of the cleaning blade.
[0144]
In addition, the friction coefficient described in the text is calculated using the Euler belt method (formula calculated based on Euler's formula).
A photoconductor for measurement is fixed to a pedestal, and a high-quality paper of 85 μm in thickness (made by Ricoh, type 6200 paper, using vertical eyes) cut to a width of 30 mm and a length of 290 mm is prepared as a belt. Place it on your body, attach a weight of 100gr to one end of the belt, attach a digital force gauge for weight measurement to the other end, pull the digital force gauge slowly, and start the belt movement Read the weight and calculate the (static) friction coefficient (μs) from the following formula.
[0145]
[Expression 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, although it demonstrates in more detail using an Example, this invention is not limited by these Examples.
<Evaluation electrophotographic photoreceptor>
1) Preparation of a three-layered photoreceptor having a filler non-dispersed charge transport layer
A three-layered photoreceptor having a filler non-dispersed charge transport layer used for evaluation was prepared by the following means.
After dip-coating with an undercoat layer (UL) coating solution having the following composition as a conductive support, a JIS3003 series aluminum alloy drum machined to φ30 mm, length 340 mm, wall thickness 0.750 mm, 120 ° C. 20 After being partially dried and coated with an undercoat layer of 3.5 μm and then with a coating solution for a charge generation layer (CGL) using the charge generation material described in the following [Chemical Formula 1], it is dried by heating at 120 ° C. for 20 minutes. Thus, a 0.2 μm charge generation layer was formed. Furthermore, it was dip-coated in a charge transport layer (CTL) coating solution using the charge transport material described in [Chemical Formula 2] below, the pulling speed condition was changed, and a filler non-dispersed charge transport layer was coated. Thereafter, heat drying was performed at 130 ° C. for 20 minutes to prepare an organic photoreceptor having a filler non-dispersed charge transport layer having an average film thickness of 20 μm.
The average film thickness as used herein refers to an average value obtained by measuring 13 points at intervals of 20 mm starting from 50 mm from the end using an eddy current film thickness meter (type mms) manufactured by Fischer.
The “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 & Chemicals, Inc.)
Melamine resin 4 parts
(Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide (CR-EL, manufactured by Ishihara Sangyo) 40 parts
200 parts of methyl ethyl ketone
[0149]
[Coating liquid for charge generation layer]
10 parts of a bisazo pigment having the structure shown in the following [Chemical Formula 1]
[0150]
[Chemical 1]

Polyvinyl butyral 2 parts
2-butanone 200 parts
400 parts of cyclohexanone
[0151]
[Coating liquid for filler non-dispersed charge transport layer]
Bisphenol Z-type polycarbonate 10 parts
(Teijin Chemicals Limited: Z Polica Mv50,000)
8 parts of a low molecular charge transport material having the structure shown in the following [Chemical Formula 2]
[0152]
[Chemical 2]

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 between 2 to 10 μm by spray coating.
Four types of binder resin (bisphenol Z type polycarbonate resin) and low molecular charge transport material (donor) described below on the filler non-dispersed charge transport layer, primary particle size 0.3, 0.5, 0.7 and 1 μm. Prepare the following inorganic filler, put each inorganic filler, dispersion aid and solvent into a glass pot, disperse with a ball mill for 24 hours to make a coating solution, and reciprocate 1 to 5 times using the spray method. A dispersed charge transport layer was applied. After the tentacles were dried, the electrophotographic photosensitive member for evaluation having a filler-dispersed charge transport layer was prepared by heating and drying at 150 ° C. for 20 minutes.
[0154]
[Filler-dispersed charge transport layer coating solution]
Bisphenol Z-type polycarbonate 10 parts
(Teijin Chemicals Limited: Z Polica Mv50,000)
7 parts of a charge transport material represented by the following structural formula [Chemical Formula 3]
[0155]
[Chemical 3]

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

(Note) In the table, Rz _JIS Is the 10-point average roughness, Rz is the maximum height, and the filler particle size is the average particle size.
[0157]
<Charging member>
Charging member for non-contact charging
Electric resistance is 4 × 10 on a brass rod of φ7mm ⁶ After applying epichlorohydrin rubber in which silica and fluororesin dispersed in Ω · cm (when 100 VDC is applied), it is polished and polished, and the 10-point average roughness is 72 μm, and the JIS-A hardness is 87 degrees outer diameter φ10 mm × 329 mm A charging member having an effective charging width: 308 mm was prepared.
A non-contact charging member using PET (polyethylene terephthalate) cut into a rhombus having a thickness of 49 μm, a width of 7.5 mm, and a length of 31 mm on the inside 1 mm from both ends of the charging member was used as a spacer. The average distance between the photosensitive member and the charging member was 62 μm.
[0158]
<Method for Applying Lubricant to Photoreceptor Surface Layer>
A pulverized toner having a weight average particle diameter of about 4.8 μm and an average circularity of 0.924 (SiO 2 as a flow agent) ₂ = 0.7%, TiO ₂ = 0.8% addition) 0.03% zinc stearate (SZ2000) with an average particle size of 0.3 μm or 0.17% by weight tetrafluoroethylene (PTFE, Lubron L-2 Daikin Industries) This was carried out by a method of applying a lubricant to the surface of the photoreceptor.
A magnetic carrier (FPC-300LC) having a weight average particle size of 58 μm was used as the developer carrier.
[0159]
<Cleaning device>
1. Cleaning brush
Nylon fiber beltlon (made by Kubota Textile) with a fiber diameter of 15 denier, 48 filament / 450 loop, loop length of 3 mm, and acrylic fiber SA-7 (made by Ashiya Co., Ltd.) are each cut into a string with a width of 10 mm. Then, it was attached to a brass rod rod having a diameter of 5 mm by using a winding adhesive and fixed, and two types of two cleaning brushes were produced.
Next, resin coating was applied to each two of them to increase the strength of the fibers. The conditions are water-based urethane adhesive Merci 585 manufactured by Toyo Polymer Co., Ltd., and epoxy AD-C-65 manufactured by Toyo Polymer Co., Ltd. as a curing agent. The cross-linking agent is immersed 2 mm from the surface of the cleaning brush in a liquid obtained by adding 1.25 water so that the amount of the cross-linking agent is 5% by weight with respect to 5 parts of the main agent. Drying was performed at 10 ° C. for 10 minutes.
[0160]
2. Cleaning blade
JIS-A hardness of 77 degrees, 2mm thickness, 11.6mm width, 326mm long strip (sheet) polyurethane rubber on a 1mm plate thickness and 363mm length L-shaped iron member with hot melt adhesive The attached one was used. The free length is 8 mm.
[0161]
<Evaluation method>
A four-tandem color laser printer (Ipsio Color 8000 (28 sheets / min) Ricoh) equipped with four photoconductors, four Y, M, C, and Bk developers and one transfer belt as an evaluation device Prepared). However, in the experiment, dummy drums were mounted at positions Y, M, and Bk, and cyan toner was added at position C for evaluation. As a means for applying a lubricant to the photoreceptor, zinc stearate was contained in an amount of 0.03% by weight based on the toner.
The number of evaluation sheets is 50,000 for each A4 size, and the initial photosensitive layer thickness and the thickness after 50,000 are measured at 13 points at intervals of 20 mm using an eddy current film thickness meter (Fischer type mms). The abrasion amount (average value of 13 points) of the photosensitive layer was evaluated.
[0162]
<Examples 1-4>
From the photoreceptor sample shown in Table 1, the particle size of the filler added in the filler-dispersed charge transport layer is different. Four samples of 4, 8, 9, and 12 were selected and used for evaluation. The mounting position of each photoconductor is only the cyan position, and dummy photoconductors having equivalent characteristics are mounted at the other three locations. A non-contact charging roller is mounted for charging, and a DC voltage of -770 V and an AC voltage of Peak to Peak voltage (Vp-p) of 1850 V / 1350 Hz are superimposed and applied to the charging member, and the charging potential 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 development bias was set to -600V.
The cleaning device is composed of a cleaning blade and a cleaning brush. The rotation direction of the cleaning brush is opposite to the rotation of the photosensitive member (forward direction), and the flicker bar is not installed on the brush.
Ricoh cyan toner having a melting point of 160 ° C. was used as the toner, and 0.03% by weight of a lubricant (zinc stearate) was added to adjust the toner to 5% by weight with respect to the carrier (FCP-300LC). .
The number of evaluation sheets was 50,000 sheets in A4 size.
[0163]
Evaluation items are I) Coefficient of friction, II) Uniformity of 1-dot halftone image (using internal pattern of printer), III) Photoreceptor appearance characteristics (confirmation of filming), IV) Photoreceptive layer wear (Fischer film) Thickness meter mms), V) Resolution (using Kodak Drawing A (JIS Z 6008)) and surface roughness (10-point average roughness Rz) _JIS The maximum height Rz) was confirmed, and the effect of a nylon cleaning brush (Beltlon brush) in which the wear force at the time of applying the lubricant to the photosensitive member was reinforced was confirmed. The results are shown in Table 2.
[0164]
Even after 50,000 sheets, the surface layer of the photoreceptor was glossy, and the coefficient of friction was as good as 0.3. As a result, the abrasion amount of the photosensitive layer was as small as 0.3 to 0.4 μm, and the filming due to the toner and paper dust was not in the image forming region and there was no image flow phenomenon.
After the evaluation, the cleaning brush was removed, the toner was removed sufficiently, and the state of the resin peeling was confirmed with an optical microscope, but although it was peeled off, it was still covered and the cleaning property was sufficient. Observed.
[0165]
[Table 2]

In the table, Rz _JIS , Rz represents surface roughness, Rz _JIS Is the 10-point average roughness, and Rz is the maximum roughness. The photosensitive layer wear amount represents the wear amount per 10,000 sheets after evaluation of 50,000 sheets. 1-dot halftone uniformity is an evaluation result of an A3 size image. The resolution represents “vertical resolution / horizontal resolution”. If the resolution is 5.6 lines / mm or more, there is no practical problem.
Judgment ○ indicates that there is no practical problem, Δ indicates evaluation of 50,000 sheets and the problem is minor in practical use, but will be a problem in the future, and × indicates that evaluation is 50,000 sheets and the practicality is low.
The same applies to the following tables.
[0166]
<Comparative Examples 1-4>
As a photoreceptor for evaluation, No. 1 described in Table 1 was used. Photoconductors 4B having the same specifications as those of 3, 5, 10 and No4 were prepared, and each was mounted on a cyan photoconductor unit. Replace the cleaning brush with the original loop-shaped cleaning brush that does not reinforce the wear force, install a normal loop brush, and evaluate whether filming has occurred when lubricant is applied to the photoreceptor. Carried out. The evaluation method is the same as in Examples 1-4. The results are shown in Table 3.
In the cleaning brushes that did not enhance the wear force, film-like filming occurred, but no. 7 (Rz _JIS = 1.2 μm, Rz = 1.75 μm) and No. 10 (Rz _JIS = 0.93 μm, Rz = 1.63 μm), the filming after 50,000 sheets spread over the entire surface, and the charging roller was also observed as a pale-white stain over the entire length. Filming was also observed on the other two photoconductors. 7 and no. Compared to 10, the degree was good.
[0167]
[Table 3]

[0168]
<Comparative Examples 5-8>
As a photoreceptor for evaluation, No. 1 described in Table 1 was used. 1, 2, no. No. 8 produced with the same specifications as in No. 8. 8B and no. Fifteen photoconductors were prepared and each was mounted on a cyan photoconductor unit. As the cleaning brush, a loop-shaped cleaning brush having the same specifications as those used in Examples 1 to 4 with enhanced wear force was used, and a toner to which zinc stearate was not added was used as the developer cyan toner. Evaluation was carried out in the same manner as in Examples 1 to 4, and the effect was confirmed when using a cleaning brush with an enhanced wear force in the absence of zinc stearate. The results are shown in Table 4.
In the state where the cleaning brush for enhancing the wear force was not used and the lubricant was not applied, the friction coefficient was increased, and as a result, the photosensitive layer was greatly worn. As a result of the increase in the coefficient of friction, the cleaning blade is distorted (twisted) and the toner is more easily removed. Therefore, all the photoconductors to which fillers are added have filming phenomenon, but the photoconductors do not disperse the filler. In this case, toner omission occurred, but filming did not occur due to much wear.
[0169]
[Table 4]

[0170]
<Examples 5 to 8>
Filming generation and filming when combined with a cyan toner in which zinc stearate is added to a loop brush in which the thickness of the filler non-dispersed charge transporting layer (charge transporting layer) is changed from 10 to 40 μm and the wear resistance is enhanced. The effects due to The evaluation method was the same as that described in Examples 1 to 4. The results are shown in Table 5.
Even if the thickness of the photosensitive layer is changed, the effect of the loop brush with increased wear force is maintained, and no filming is generated in all four samples. In the state, resolution did not decrease. The photoconductor with a large film thickness (No. 14 photoconductor) shows a decrease in resolution, resulting in thick characters that do not depend on the image flow, and the resolution is 5.0 lines / mm in length and 5.6 lines / mm in width. It 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. As the evaluation photoreceptor, No. 1 described in Table 1 was used. Photoconductor Nos. 3 and 4 manufactured with the same specifications as those in FIGS. 3B, no. 4C and No. No. 6 photoconductor was used, and the other conditions were evaluated in the same manner as in Examples 1 to 4. The results are shown in Table 6.
Even when the lubricant was changed to zinc stearate, filming was satisfactorily suppressed and good results were obtained. The image quality was sharper than zinc stearate and a sharp line image was obtained. The coefficient of friction was 0.2, and the photosensitive layer was less worn than when zinc stearate was used.
[0173]
[Table 6]

[0174]
<Examples 12 to 16>
Replace the loop brush with SA-7, an acrylic fiber with enhanced wear, and use 5% by weight of cyan toner with 0.15% polytetrafluoroethylene (PTFE) added to the toner. did. As the evaluation photoreceptor, No. 1 described in Table 1 was used. Photoreceptors No. 4, 5, 6, 12, and 1 produced according to the same specifications as those described above. 4D, 5B, 6B, 12B and 1B were used, and other conditions were evaluated in the same manner as in Examples 1 to 4. The results are shown in Table 7.
The results were the same as in Examples 1 to 4, and there was no filming in all 5 samples, and there was no reduction in resolution. In addition, the coefficient of friction remained at a low level and there was little wear. However, no. The photoreceptor of 1B had a wear of as much as 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>
・ Production method of photoconductor for evaluation
The photoreceptor used in the present invention was prepared as follows.
Dip-coating using an undercoating layer (UL) coating solution of the following composition on an aluminum drum with a diameter of 100 mm, length of 360 mm, and wall thickness of 1 mm, followed by heating and drying at 130 ° C. for 30 minutes, an undercoating layer of about 4 μm Formed.
Next, dip coating is performed using a charge generation layer (CGL) coating solution, and a 0.2 μm charge generation layer is formed by heating and drying at 150 ° C. for 25 minutes. Further, a charge transport layer (CTL) coating is formed. Immersion coating was performed using the working solution, and an organic photoreceptor was prepared by applying a charge transport layer of about 25 μm by heating and drying at 140 ° C. for 30 minutes. On this photoreceptor, a binder resin and a donor, inorganic fine particles (metal oxide) having an average particle size of 0.3, 0.5, 0.7 μm, or 1.0 μm, an additive and a solvent are placed in a glass pot, Disperse with a ball mill for 24 hours, make a coating solution with an average particle size (measured with CAPA500 manufactured by Horiba Seisakusho) of about 0.5 μm, and apply 4 times (about 1.2 to 1.5 μm / time) using the spray method. The electrophotographic photosensitive member was completed by heating and drying to form a coating layer of about 5 μm.
All the 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 & Chemicals, Inc.)
Melamine resin 4 parts
(Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide (CR-EL, manufactured by Ishihara Sangyo) 40 parts
200 parts of methyl ethyl ketone
[Coating liquid for charge generation layer]
2 parts of oxotitanium phthalocyanine pigment (Ricoh)
Polyvinyl butyral (UCC: XYHL) 0.2 part
50 parts of tetrahydrofuran
[Coating fluid for charge transport layer (inorganic filler non-dispersed charge transport layer)]
Bisphenol A type polycarbonate 10 parts
(Teijin Chemicals: Z Polyca)
12 parts of a low molecular charge transport material having the structure shown in [Chemical Formula 4] below
[0178]
[Formula 4]

100 parts methylene chloride
Methyl phenyl silicone oil (50cs) 1 part
[Coating liquid for filler-dispersed charge transport layer]
The coating liquid for the filler-dispersed charge transport layer is mixed so that the binder resin and the inorganic fine particles are 20% by weight, and the ratio of the charge transport material and the binder resin is 7/10. Three sprays were performed to form four coating layers.
Binder resin: 10 parts of polycarbonate resin
(Z Polica, manufactured by Teijin Chemicals Ltd., Mv 50,000)
Filler: 5.7 parts of alumina powder
(AA-03, AA-05, AA-07, AA-10, manufactured by Sumitomo Chemical Co., Ltd.)
However, AA-07 was also produced by attaching it to a photoreceptor (sample No. 20) added with 11.4 parts in addition to 5.7 parts.
7 parts of low molecular charge transport material shown in [Chemical Formula 5] below
[0179]
[Chemical formula 5]

Dispersing aid: (BYK-P104, manufactured by Big Chemie Japan) 0.1 part
700 parts of tetrahydrafuran
200 parts of cyclohexanone
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 Co., Ltd.) in which the charging device was modified for a non-contact charging roller was prepared.
As the non-contact charging member used for charging the photoreceptor, epichlorohydrin rubber having the same specifications as described in the above example was used, and finished to an outer diameter of φ18 mm. PET (polyethylene terephthalate film) having a rhombus shape having a width of 10 mm and 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 core metal 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.
When these members are mounted on the evaluation device, 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 to adjust the charging level from −700 to −710 V. And 100,000 sheets of paper were evaluated. Incidentally, the image portion potential was -150V to -180V.
As the developer, a toner obtained by adding 0.02% of zinc stearate to a black toner for IMAGIO Neo600 was used. The results are shown in Table 9.
Filming was not generated in any of the photoreceptor samples, and the gloss was kept relatively good. Also, the resolution was good and the sharpness was slightly reduced compared to the initial value, but the results shown in Table 9 were obtained, and all the samples had no problem. Further, the resin coating layer of the loop brush had a part that was locally peeled off, but it was not in a situation where the cleaning property was deteriorated.
[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 photoconductor for evaluation, no. 19 and 20 photoreceptors were used and evaluated in the same manner as in Examples 17-19. The results are shown in Table 10.
Increased surface roughness (Rz _JIS 1.0 or more and Rz is 1.5 or more), the amount of toner blade missing increased, so that the abrasion force with the cleaning brush was insufficient, and the occurrence of filming was confirmed locally.
For this reason, the image quality (unevenness in the halftone image, the resolution is locally reduced, and the character image is crushed due to the fatness) is 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 described above, as is clear from the detailed and specific description, the configuration according to claim 1 of the present invention allows the initial and A4 size paper 10-point average roughness Rz after printing 50,000 sheets _JIS A cleaning brush and a cleaning blade are simultaneously operated while applying a lubricant to a photoconductor having a maximum height Rz of 0.4 to 1.5 μm, and a φ30 mm photoconductor A4 size paper By maintaining the abrasion amount of the photosensitive layer per 10,000 sheets at 0.1 to 0.5 μm from the surface layer, residual powder (consisting of toner, paper dust, dust, etc.) cleaning failure, corona product Filming caused by such actions can be prevented, and the coefficient of friction of the photoreceptor surface layer is maintained at a low level, so that there is no deterioration in image quality such as resolution reduction and image flow, and abrasion of the photosensitive layer. Therefore, it is possible to maintain a sharp image with no unevenness over a long period of time. In addition, a loop brush is formed by using any one of polyester fiber, nylon fiber, and acrylic fiber as a cleaning brush, and is arranged so as to be brought into surface contact with the photoreceptor and rubbed. The above residual powder can be cleaned stably over a long period of time, and the filming on the photosensitive layer can be removed uniformly and uniformly by reinforcing the fibers. In addition, at least the fibers in the area to be cleaned by the loop-shaped cleaning brush are coated with a resin and mechanically strengthened, so that the filming fixed to the photosensitive layer is removed by the rubbing force of the cleaning brush. In addition to cleaning, the generated fine filming is scraped to a small extent to prevent the spread, so that a high-quality image can be maintained over a long period of time. Further, according to the structure of claim 2, the cleaning brush can easily and quickly produce a cleaning brush by providing means for winding and fixing the loop brush cut into a strip shape spirally on the core metal without gaps. Can do. The brush produced in this way is free from slipping and ensures stable cleaning of the residual powder over a long period of time. In addition, according to the configuration of claim 3, by applying the resin layer for mechanical strengthening of the loop brush by the dipping method, sufficient resin coating can be easily and surely performed, so that there is little deterioration, Cleaning performance can be maintained over a long period of time. According to the fourth aspect of the present invention, it is possible to prevent toner from collecting in the back of the brush and deteriorating the cleaning function by not using the flicker bar for the loop brush. In addition, since there is no mechanical damage due to the flicker bar, good cleaning properties can be maintained over a long period of time. According to the fifth aspect of the present invention, the rotation of the loop brush is rotated in the direction opposite to the rotation of the photosensitive member, whereby the photosensitive layer is not excessively scraped and uneven wear is reduced, and the long life of the photosensitive member is achieved. Also, the occurrence of abnormal images can be avoided. According to the sixth aspect of the present invention, a filler having a particle diameter of 0.3 to 0.7 μm is added in an amount of 20% by weight to 35% by weight in order to provide wear resistance to the charge transport layer of the photoreceptor. Even when a strengthened loop brush is used, the photosensitive layer is not worn more than necessary, an image with good resolution and sharpness can be formed, and the life of the photoreceptor can be extended. According to the seventh aspect of the present invention, the friction coefficient can be reduced by using either zinc stearate or polytetrafluoroethylene as the lubricant to be applied to the surface layer of the photoreceptor. By maintaining the ratio between 2 and 0.45, the sharpness is good, and it is possible to prevent the photosensitive layer from being worn more than necessary. Further, since the lubricant appropriately enters the valley portion on the surface of the photoreceptor, the adhesion of the corona product is suppressed, which is a measure for suppressing the image flow. Further, according to the structure of claim 8, by using a contact charging roller that forms a nip with the photosensitive member as means for charging the photosensitive member, charging with good image uniformity can be performed at a low voltage. Image quality with high uniformity and high S / N can be guaranteed. According to the ninth aspect of the present invention, as a means for charging the photoconductor, the fine gap is kept between 30 μm and 100 μm between the photoconductor and the charging member, so that the charging roller is less contaminated. Since pinholes due to the piercing of a minute metal such as a carrier are reduced, the margin for discharge breakdown is increased. Further, stable charging can be performed. Further, according to the configuration of claim 10, the electrophotographic photosensitive member according to any one of claims 1 to 9, a charging device, a cleaning device including a cleaning brush and a cleaning blade, and indirect using a lubricant applying means. By using an image forming method using electrophotography, it is possible to form an image with good sharpness without filming and to provide a stable image over a long period of time because there is no excessive wear of the photosensitive layer. . Further, according to the structure of claim 11, at least one unit selected from the electrophotographic photosensitive member according to claims 1 to 9, a charging device, a cleaning device comprising a cleaning brush and a cleaning blade, and a lubricant applying means. By configuring a process cartridge that is detachable from the image forming apparatus, it is possible to take out the image forming apparatus in a short time and install it when an abnormal image occurs or when the life of the unit is reached. Therefore, it is possible to reliably restore the original state.
[Brief description of the drawings]
FIG. 1 is a schematic view of an image forming apparatus for explaining a copying process of the present invention provided with a cleaning device comprising a cleaning brush and a cleaning blade not provided with a flicker bar.
FIG. 2 is another schematic diagram of an image forming apparatus illustrating a copying process according to the present invention, which includes a cleaning device including a cleaning brush and a cleaning blade not provided with 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 color laser beam printer using four photoconductors and developing devices for four colors of magenta, cyan, yellow, and black.
FIG. 4 is a schematic diagram for explaining a configuration of a function separation type photoreceptor used in the present invention.
FIG. 5 is a schematic diagram illustrating a function-separated type photoreceptor in which the charge transport layer of FIG. 4 includes two layers, a filler non-dispersed charge transport layer and a filler dispersed charge transport layer.
FIG. 6 shows the surface roughness of the photoreceptor surface layer (10-point average roughness Rz). _JIS It is a graph explaining the filler particle size dependence of the maximum height Rz).
FIG. 7 shows the surface roughness of a photoreceptor surface layer of a 60 mm diameter photoreceptor (average roughness Rz at 10 points). _JIS , Maximum height Rz) is a graph for explaining the dependency of filler addition amount on the charge transport layer.
FIG. 8 is a surface roughness of a photoreceptor surface of a 30 mm diameter photoreceptor (average roughness Rz at 10 points). _JIS , Maximum height Rz) is a graph for explaining the dependency of filler addition amount on the charge transport layer.
FIG. 9 is a schematic view illustrating a state in which the fibers of the 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 the arrangement of a cleaning device for explaining a combination of a strip-shaped cleaning blade and a cleaning brush.
FIG. 12 is a schematic view showing the arrangement of a cleaning device for explaining a combination of a knife-edge 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 view showing a contact state of a knife-edge 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: Photoconductor for electrophotography (photoconductor)
2: Charging device
3: Image exposure device
4: Development 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: Lubricating device
201: Lubricant
202: Lubricating brush

Claims (11)

A voltage is applied to a charging member constituting a charging device disposed so as to face the electrophotographic photosensitive member to uniformly charge the electrophotographic photosensitive member, and an electrostatic latent image is formed by light writing from an image exposure device. The electrostatic latent image is formed and visualized by a developing device, transferred to a transfer target by a transfer device to which a voltage is applied, and a cleaning device composed of a cleaning brush and a cleaning blade is used. In an image forming apparatus using indirect electrophotography that forms an image by cleaning residual powder, the cleaning brush is composed of any one of polyester fiber, nylon fiber, and acrylic fiber. The loop brush is fixed on the mandrel, and the resin is applied to the surface of the cleaning brush that contacts the photosensitive member and to the inside. Be those which are fabric, the cleaning brush is said with being placed in the cleaning device to evenly surface-contact with the electrophotographic photoreceptor, 10-point average of initial and A4-size paper 50,000-sheet after printing Roughness Rz A lubricant is applied to the surface of the electrophotographic photosensitive member having a _JIS of 0.3 to 1.0 μm and a maximum height Rz of 0.4 to 1.5 μm, and the cleaning brush and the cleaning blade are provided. By simultaneously operating (in terms of φ30 mm electrophotographic photoreceptor), image formation is achieved by maintaining the average abrasion amount (t) of the photosensitive layer per 10,000 A4 size paper at 0.1 μm ≦ t ≦ 0.5 μm. An image forming apparatus. The means for fixing the loop brush on the mandrel is such that the strip-shaped loop brush is helically wound and fixed on the mandrel without a gap, and the cleaning brush is 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 be in surface contact with the electrophotographic photosensitive member evenly. 3. The image forming apparatus according to claim 2 , wherein the surface of the cleaning brush that comes into contact with the photoreceptor and the application of the resin in the inner direction are performed by a dipping method. The image forming apparatus according to any one of claims 1 to 3, characterized in that flicker bar to the cleaning brush is not attached. Any the cleaning brush rotates in a forward direction of the rotation of the electrophotographic photosensitive member by rubbing, of claims 1 to 4, characterized in that cleaning the residual powder on the electrophotographic photosensitive member An image forming apparatus according to claim 1. The photosensitive layer constituting the electrophotographic photoreceptor is composed of a charge generation layer and a charge transport layer, and the charge transport layer is further composed of an inorganic filler non-dispersed charge transport layer containing no inorganic filler and an inorganic filler dispersed charge transport layer. In the inorganic filler-dispersed charge transport layer, the inorganic filler having an average particle size of 0.3 to 0.7 μm contains 20% by weight to 35% by weight of the total charge transport layer containing the inorganic filler. the image forming apparatus according to any one of claims 1 to 5, characterized in. By applying a lubricant of either zinc stearate or polytetrafluoroethylene (PTFE) to the surface layer of the electrophotographic photoreceptor directly or indirectly using an application means, the friction coefficient is reduced. The static friction coefficient measured by the Euler belt method (high quality paper cut to a width of 30 mm and a length of 290 mm (made by Ricoh, type 6200 paper, using vertical eyes)) is 0.20 to 0.45 during image formation. the image forming apparatus according to any one of claims 1 to 6, characterized in that. The image according to any one of claims 1 to 7 , wherein charging when forming an electrostatic latent image on the electrophotographic photosensitive member is performed by surface contact with a charging member having a nip on the electrophotographic photosensitive member. Forming equipment. 2. The charging operation for forming an electrostatic latent image on the electrophotographic photosensitive member is performed by keeping the charging member and the electrophotographic photosensitive member in a non-contact state with a separation of 30 to 100 μm. The image forming apparatus according to claim 7 . The electrophotographic photosensitive member used in the image forming apparatus according to any one of claims 1 to 9, the charging device, the cleaning device comprising a cleaning blade and a cleaning brush, with a lubricant application means, to perform the image formation An image forming method by indirect electrophotography characterized by the above. The electrophotographic photosensitive member used in the image forming apparatus according to any one of claims 1 to 9, a charging device, a developing device, a cleaning device composed of the cleaning brush and a cleaning blade, at least one element selected from the lubricant application member A process cartridge that integrally supports two units and is detachable from an image forming apparatus main body.

Images