JP2004138643A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a cleaning step is satisfactorily performed and images of good quality are obtained over a prolonged period of time. <P>SOLUTION: The image forming apparatus uses an indirect electrophotographic method in which electric charges are imparted by a charging device to an electrophotographic photoreceptor to form an electrostatic latent image by photolithography, the electrostatic latent image is converted to a visible image with a toner, the toner is transferred to a transfer member, and the photoreceptor is cleaned with a cleaning blade. In the image forming apparatus, when the maximum valley depth of the surface roughness of the electrophotographic photoreceptor is represented by Rv, the maximum peak height by Rp, and the minimum particle diameter of the toner by D, the sum Ry of the maximum valley depth Rv and the maximum peak height Rp and the minimum particle diameter D of the toner satisfy Ry<D. The cleaning blade is held in such a way that it comes in contact with the electrophotographic photoreceptor in a counter direction. The cleaning blade is formed of a rubber-like elastic body having a JIS-A hardness of 75 to 90°, wherein the edge part which comes in contact with the electrophotographic photoreceptor has a knife or strip shape and has been reinforced with a metal strip on one face in the lengthwise direction. <P>COPYRIGHT: (C)2004,JPO

Description

【０２５３】
〔電荷発生層用塗工液〕
下記構造のビスアゾ顔料　　　　　　　　　　　　　　　　　　　１０部
【化１】

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
【０２５４】

【化２】

【０２５５】
２）フィラー分散電荷輸送層を有する感光体の作製
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。
ここで、冷却後引き続きフィラー分散電荷輸送層を塗工したのは、溶媒に因り界面が解け合い、明確な界面を形成させないためであるが、１晩程度の放置では殆ど問題はない。しかし、数週間放置すると酸化などにより、表面準位が変わり、局部的にバリア（捕獲準位）が出来、画像品質に悪影響が出やすいためである。
【０２５６】
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）、一次粒径が０．２、０．３、０．５、０．７および１μｍの５種類の無機フィラー（α−アルミナ）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。
【０２５７】

【化３】

【０２５８】
作製した感光体の特性一覧を表１に示す。
【０２５９】
【表１】

【０２６０】
帯電部材：
１）接触帯電用の帯電部材
本発明の実施例に記載の帯電部材は、６ｍｍの真鍮製ロット棒にカーボンを均一分散し、電気抵抗を６×１０^５Ω・ｃｍ（１００ＶＤＣ印加時）に調整したエピクロルヒドリンゴムを３ｍｍの厚さになるように塗布して研磨し、その層上にエピクロルヒドリンゴムにカーボン、シリカ、フッ素樹脂を分散し電気抵抗が（３〜５）×１０^８Ω・ｃｍ（１００ＶＤＣ印加時）になる様に調合したエピクロルヒドリンゴムを厚さ１ｍｍに均一塗布して、φ１４ｍｍ×３１４ｍｍ（有効帯電幅：３１２ｍｍ）の寸法形状にしたものである。（電子写真複写機、リコー社製　イマジオＭＦ２２００に使用）
【０２６１】
２）非接触帯電用の帯電部材
帯電部材−１
８ｍｍの真鍮製ロット棒に電気抵抗が（４〜６）×１０^５Ω・ｃｍ（１００ＶＤＣ印加時）となるカーボン、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、φ６ｍｍの真鍮製ロット棒に厚さが１ｍｍと成る様に塗布したφ１４ｍｍ×３１４ｍｍ（有効帯電幅：３１２ｍｍ）の帯電部材を作製した。この帯電部材の両端部から１．５ｍｍ内側に、厚さ４９μｍ、幅８ｍｍ、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した非接触帯電部材を作製した。感光体と帯電部材間の距離は平均で５６μｍであった。（電子写真複写機　イマジオＭＦ２２００に使用）
【０２６２】
帯電部材−２
８ｍｍの真鍮製ロット棒に電気抵抗が（４〜６）×１０^５Ω・ｃｍ（１００ＶＤＣ印加時）となるカーボン、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、φ６ｍｍの真鍮製ロット棒に厚さが１ｍｍと成る様に塗布したφ１０ｍｍ×３２７ｍｍ（有効帯電幅：３０８ｍｍ）の帯電部材を作製した。この帯電部材の両端部から１．５ｍｍ内側に、厚さ４９μｍ、幅８ｍｍ、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した非接触帯電部材を作製した。感光体と帯電部材間の距離は平均で５３μｍであった。
（カラーレーザービームプリンター　イプシオカラー８０００に使用）
【０２６３】
感光体表層の摩擦係数低減化方法：
本発明では、トナー中にステアリン酸亜鉛を０．０３重量％添加することによって、現像剤を介して感光体表層に潤滑剤を付与する方法で行った。
【０２６４】
現像剤＝キャリア＋トナー：
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。
トナーは下記に記載するような製造例を用いて製造された重量平均粒径が約５．１〜５．６μｍ、平均円形度０．９８７〜０．９９３のシアン、マゼンタ、イエローおよびブラック球形トナーを使用した。
また、粉砕法で製造されたトナーについては、重量平均粒径５．２μｍ〜７．５μｍ（最小粒径：２．８μｍ〜４．１）、平均円形度０．９１４〜０．９３のブラックトナーを使用した。
これらのトナーはキャリアに対して６．５重量％の割合で添加して現像剤とした。
これらのトナーには感光体表層の摩擦係数を低減化させる場合には、ステアリン酸亜鉛をトナー全重量に対し０．０３重量％添加した。
【０２６５】
次に、重合トナー（重合法で製造されたトナーの意）および粉砕トナーの製造例を示す。
【０２６６】
［重合トナーの製造例］
（１）シアン（Ｃ）トナーの製造例
（添加用ポリエステル樹脂の製造例）
冷却管、攪拌機および窒素導入管の付いた反応槽中に、ビスフェノールＡエチレンオキサイド２モル付加物６９０部、テレフタル酸２３０部を常圧下、２１０℃で１０時間重縮合し、次いで１０〜１５Ｔｏｒｒの減圧を行い、５時間反応した後１６０℃まで冷却し、これに１８部の無水フタル酸を加えて２時間反応し変性されていないポリエステル樹脂（重量平均分子量Ｍｗ：８５０００）を得た。
【０２６７】
（プレポリマーの製造例）
冷却管、攪拌機および窒素導入管の付いた反応槽中に、ビスフェノールＡエチレンオキサイド２モル付加物８００部、イソフタル酸１６０部、テレフタル酸６０部、およびジブチルチンオキサイド２部を入れ、常圧において２３０℃で８時間反応し、さらに１０〜１５ｍｍＨｇの減圧で脱水しながら５時間反応した後、１６０℃まで冷却して、これに３２部の無水フタル酸を加えて２時間反応した。次いで、８０℃まで冷却し、酢酸エチル中にてイソホロンジイソシアネート１７０部と２時間反応を行いイソシアネート基含有プレポリマー（Ｍｗ：３５０００）を得た。
【０２６８】
（ケチミン化合物の製造法例）
攪拌棒および温度計のついた反応槽中にイソホロンジアミン３０部とメチルエチルケトン７０部を仕込み、５０℃で５時間反応を行い、ケチミン化合物を得た。
【０２６９】
（トナーの製造例）
ビーカー内に前記のプレポリマー１４．３部、ポリエステル（ａ）５５部、酢酸エチル７８．６部を入れ、攪拌し溶解した。次いで、離型剤であるライスワックス（融点８３℃）１０部、銅フタロシアニンブルー顔料４部を入れ、４０℃にてＴＫ式ホモミキサーを用いて１２０００ｒｐｍで５分攪拌した後、ビーズミルで３０分間２０℃において粉砕処理した。これをトナー材料油性分散液とする。
【０２７０】
ビーカー内にイオン交換水３０６部、リン酸三カルシウム１０％懸濁液２６５部、ドデシルベンゼンスルホン酸ナトリウム０．２部を入れ、ＴＫ式ホモミキサーを１２０００ｒｐｍの回転数で攪拌しながら、この水分散液（１）に上記トナー材料油性分散液及びケチミン化合物２．７部を加え、攪拌を続けながら反応させた。
【０２７１】
反応後の分散液（粘度：３５００ｍＰ・ｓ）を減圧下１．０時間以内に５０℃以下の温度で有機溶剤を除去した後、濾別、洗浄、乾燥し、次いで風力分級し、球形状のトナー母体粒子を得た。
【０２７２】
次に、得られた母体粒子１００部、帯電制御剤（オリエント化学社製　ボントロン　Ｅ−８４）０．２５部をＱ型ミキサー（三井鉱山社製）に仕込み、タービン型羽根の周速を５０ｍ／ｓｅｃに設定して混合処理した。この場合、その混合操作は、２分間運転、１分間休止を５サイクル行い、合計の処理時間を１０分間とした。
更に、疎水性シリカ（Ｈ２０００、クラリアントジャパン社製）を０．５部添加し、混合処理した。この場合の混合操作は、周速を１５ｍ／ｓｅｃとして、３０秒混合１分間休止を５サイクル行った。
以上の様にしてシアントナーを得た。重量平均粒径は５．１μｍ（最小粒径：４．７μｍ）、平均円形度０．９９３であった。
【０２７３】
（２）マゼンタトナーの製造例
（マゼンタマスターバッチ粒子の作製）
水　　　　　　　　　　　　　　　　　　　　　　　　　　　　６００部
Ｐｉｇｍｅｎｔ　Ｒｅｄ　５７　含水ケーキ（固形分５０％）　２００部
をフラッシャーでよく撹拌する。ここに、ポリエステル樹脂（酸価；３、水酸基価；２５、Ｍｎ；３５００、Ｍｗ／Ｍｎ；４．０、Ｔｇ；６０℃）１２００部を加え、１５０℃で３０分混練後、キシレン１０００部を加えさらに１時間混練した後、水とキシレンを除去後、圧延冷却しパルペライザーで粉砕、さらに３本ロールミルで２パスしマゼンタ色のマスターバッチ顔料（ＭＢ１−Ｍ）（平均粒径約０．２μｍ）を得た。
【０２７４】
（プレポリマーの製造例）
冷却管、攪拌機および窒素導入管の付いた反応槽中に、ビスフェノールＡエチレンオキサイド２モル付加物８５６部、イソフタル酸２００部、テレフタル酸２０部、およびジブチルチンオキサイド４部を入れ、常圧において２５０℃で６時間反応し、さらに５０〜１００ｍｍＨｇの減圧で脱水しながら５時間反応した後、１６０℃まで冷却して、これに１８部の無水フタル酸を加えて２時間反応した。次いで、８０℃まで冷却し、酢酸エチル中にてイソホロンジイソシアネート１７０部と２時間反応を行いイソシアネート基含有プレポリマー（Ｍｗ：２５０００）を得た。
【０２７５】
（トナーの製造例）
ビーカー内に前記のプレポリマー１５．４部、ポリエステル樹脂５０部、酢酸エチル９５．２部を入れ、攪拌し溶解した。次いで、カルナバワックス（分子量１８００、酸価２．５、針進入度１．５ｍｍ／４０℃）を１０部、前記マスターバッチ粒子１０部を入れ、８５℃においてＴＫ式ホモミキサーにて１００００ｒｐｍで攪拌した後、実施例１同様にビーズミルにより湿式粉砕処理して、トナー材料油性分散液を得た。
【０２７６】
次いで、実施例１と同様にして得た水分散液を用いた以外は実施例１と同様にして球形状の母体トナー粒子を得た。
次いで、帯電制御材としてオリエント社製ボントロンＥ−８４をＥ−８９に変更する以外はシアントナーの製造例と同様にしてマゼンタトナーを得た。重量平均粒径は４．８μｍ（最小粒径：３．６μｍ）、平均円形度、０．９９１であった。
【０２７７】
（３）イエロー（Ｙ）トナーの製造例
顔料をハンザイエロー１０Ｇに替えた以外、前記製造方法と同様な方法で、イエロートナーを得た。
重量平均粒径は５．５μｍ（最小粒径：４．２μｍ）平均円形度０．９９１であった。
【０２７８】
（４）ブラック（Ｂｋ）トナーの製造例
顔料を銅フタロシアニンからカーボンブラックにし、前記製造方法と同様な方法でブラックトナーを製造した。得られたトナーは重量平均粒径が５．６μｍ（最小トナー：４．５μｍ）、平均円形度０．９９３であった。更に、条件の変更により、重量平均粒径が３．８μｍ（最小トナー：３．１μｍ）、平均円形度０．９８７のトナーを製造した。
【０２７９】

上記組成物エクストルーダーを用いて溶融混練後、冷却した混練物を機械的に粉砕し、粗粉砕物を、ジェット流を用いて衝突版に衝突させて微粉砕した後、気流分級機で粒径毎の分級を行い、重量平均粒径が５．２μｍ（最小粒径：２．８μｍ）、６．３μｍ（最小粒径：３．２μｍ）、７．５μｍ（最小粒径：４．１μｍ）のブラックトナーを得た。（　）内は最小粒径トナーを示す。平均円形度は０．９１〜０．９３であった。
【０２８０】
同様に、着色剤としてＣ．Ｉ．ピグメントブルー１５：３、Ｃ．Ｉ．ピグメントイエロー１７、Ｃ．Ｉ．ピグメントレッド２０２を用いて、夫々、シアントナー、イエロートナー、マゼンタトナーを得た。
【０２８１】
［クリーニングブレード］
クリーニングブレード［タイプ１］
ＪＩＳ−Ａ硬度７４度、８１度、８７度の３種のポリウレタンゴム製クリーニングブレードを、金型成形によって作製した。形成後の寸法は板厚が２．８ｍｍ、幅１５ｍｍ、長さ３２０ｍｍ、斜めカット部の長さが４ｍｍの台形状（形状は図１８の通り）である。感光体との当接部のバリをカットし、カット部の幅は約０．３ｍｍとなった。ＪＩＳ−Ａ硬度の測定はＪＩＳ　Ｋ　６３０１に準じて作製されたテクロック社製ＧＳ−７０１Ｎを使用した。導電性塗料（藤倉化成製ドータイト）をシンナーで薄く溶いて、斜めカットの側の全面に塗布し、乾燥させた。抵抗は１００Ｖ印加時２．８×１０^５Ω・ｃｍであった。
【０２８２】
前記ブレードを板厚０．８ｍｍで８度の角度で感光体とカウンター当接するように曲げた長さ３６３ｍｍの支持基体に、斜めカット部を感光体の回転方向の上流向き（転写装置側）にして、エポキシ系の２液性接着剤（アラルダイト８　２５４−０１、バンティコ社）を使用して、自由長Ｌ１が５ｍｍになるように接着し、支持基体端部と先に導電性塗料を塗布した面とを前記導電性塗料ドータイトを５カ所で導通（≒０Ω）処理を行い、クリーニング部材を完成した。（電子写真複写機には、リコー社製イマジオＭＦ２２００に使用）
【０２８３】
クリーニングブレード［タイプ２―１］
ＪＩＳ−Ａ硬度が７１度、７７度、８７度の硬度、厚みが１ｍｍ、２ｍｍのポリウレタンゴムを幅１５ｍｍ、長さ３２０ｍｍの短冊状にカットした後、ブレードの片側全面に、シンナーで薄く溶いた導電性塗料（藤倉化成製ドータイト）を塗布し、充分に乾燥させた。抵抗は１００Ｖ印加時２．８×１０^５Ω・ｃｍであった。このポリウレタンゴムに板厚０．１ｍｍの１３．５ｍｍ×３２０ｍｍにカットした硬質アルミニウム板を感光体と当接する先端部から１．５ｍｍ外して、強力両面テープで張り合わせて、硬質アルミ板と、側面に塗布した導電性塗料面とを別のドータイトで５カ所の導通処理を行った。
【０２８４】
この様にして得られたクリーニングブレードを、感光体と８度の角度で、カウンター当接出来るように加工した板厚１ｍｍ、長さが３６３ｍｍのへの字に曲げた鉄製部材に強力両面テープを使用して接着し、図１３、若しくは図１５に示す形状のクリーニングブレードを作製した。（電子写真複写機には、イマジオＭＦ２２００に使用）
【０２８５】
クリーニングブレード［タイプ２−２］
ＪＩＳ−Ａ硬度が７７度の板厚が１ｍｍのポリウレタンゴムを幅１０ｍｍ、長さ３２５ｍｍの短冊状にカットした後、ブレードの片側全面に、シンナーで薄く溶いた導電性塗料（藤倉化成社製、ドータイト）を塗布し、充分に乾燥させた。抵抗は１００Ｖ印加時３．５×１０^５Ω・ｃｍであった。このポリウレタンゴムに板厚０．１ｍｍで８．５ｍｍ×３２５ｍｍにカットした硬質アルミニウム板を感光体と当接する先端部から１．５ｍｍ外して、強力両面テープで張り合わせて、硬質アルミ板と、側面に塗布した導電性塗料面とを別のドータイトで５カ所の導通処理を行った。
【０２８６】
この様にして得られたクリーニングブレードを、感光体と８度の角度で、カウンター当接出来るように加工した板厚１ｍｍ、長さ３２５ｍｍのＬ字型の鉄製治具にエポキシ系の２液性接着剤（アラルダイト８　２５４−０１　バンティコ社）を使用して接着して図１３、若しくは図１５に示す形状のクリーニングブレードを作製した。（リコー社製カラーレーザービームプリンター、イプシオカラー８０００に使用）
【０２８７】
クリーニングブレード［タイプ３（純正クリーニングブレード）］
ＪＩＳ−Ａ硬度が７７度（純正クリーニングブレード）で、厚み２ｍｍ、幅１５ｍｍ、長さ３２０ｍｍの短冊状のポリウレタンゴムを板厚１ｍｍ、長さが３６３ｍｍのへの字に加工された鉄製部材にホットメルト接着剤で取り付けられたものである。自由長は８ｍｍである。なお、タイプ３では導電性塗料の塗布は行われていない。
【０２８８】
評価方法：
感光体およびクリーニングブレード用の評価機として、光源の発振波長を６５５ｎｍとするＬＤ素子を用いた接触帯電方式で、感光体と現像装置、クリーニングブレードが一体構成となったプロセスユニットを内蔵する、乾式電子写真複写機（イマジオＭＦ２２００、リコー社製）および、非接触帯電方式、感光体とクリーニングブレードを一体構成とするプロセスユニットを内蔵する、４連タンデム方式のカラーレーザービームプリンター［ＣＬＢＰ］（イプシオカラー８０００、リコー社製）を用意した。
【０２８９】
評価用に用意した電子写真複写機は帯電装置への高圧電源供給が直流電圧であるため、交流電圧が重畳可能な高圧電源（長野愛知電気製、タイプＨＶ−２５５）を別途用意し、標準設定の直流電源と切り替えながらの評価を実施した。
帯電部材に交流重畳直流電圧を印加するする場合には、交流電圧を１５００Ｖ／１３５０Ｈｚに固定し、直流電圧を調整して、現像装置位置での暗部電位を設定した。
カラーレーザービームプリンターは標準設定（デフォルト）の状態で使用し評価を行った。
【０２９０】
評価枚数はＡ４サイズ各５万枚（Ａ４サイズ）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）を使って測定し、感光層の摩耗量を評価した。
【０２９１】
鉛筆硬度はＪＩＳ　Ｋ　５４０１に基づいて作製された鉛筆引っ掻き試験器（表面性測定器　新東科学社製　ＨＥＩＤＯＮ−１４型）とＪＩＳ規格標準鉛筆（三菱鉛筆“ユニ”）とを使用し、加重に１００ｇの分銅を用いて、測定用に作製した感光体を５０×８０（ｍｍ）の大きさに切断して測定した。
真円度、真直度は表面粗さ測定器（東京精密社製　サーフコム１４００Ｄ、ピックアップ：Ｅ−ＤＴ−Ｓ０２Ａ）を用いて、感光体長手方向１３カ所、周方向９０度毎に４カ所測定した。
【０２９２】
摩擦係数の測定は、測定に供する感光体を台座に固定して、幅３０ｍｍ×長さ２９０ｍｍ×厚み８５μｍの上質紙（リコー社製、タイプ６２００ペーパー、縦目使用）をベルトとし、前記上質紙を感光体の周方向に乗せ、ベルト端部の一方に１００ｇｒのおもりを取り付け、もう一方の片端に重量測定用のデジタル・フォース・ゲージを取り付け、デジタル・フォース・ゲージをゆっくり引き、ベルトの移動開始時の重量を読みとり、オイラーの方式より導き出された下式より（静止）摩擦係数μｓを算出した。
μｓ＝２／π×ｌｎ（Ｆ／Ｗ）
ただし、μｓ：静止摩擦係数、Ｆ：読みとり荷重
Ｗ：分銅の重さ　　π：円周率
【０２９３】
画像品質評価は、電子写真複写機で評価する場合は、画像品質評価は、ＪＩＳＺ　６００８にしたがって作成された試験票板（コダック社製）を使用して解像度を評価し、別途用意したリコー製テストチャートでドットパターンの再現性及び地肌汚れの評価を実施した。
【０２９４】
一方、カラーレーザービームプリンター（非接触帯電法−交流電圧重畳直流電圧印加方式）で評価する場合は、別途用意したパソコンに入力した各種パターンを使用して、解像度、１ドットパターンの再現性、ノイズ、色むら等についての評価を行った。
【０２９５】
評価時以外の通紙ランニング中の原稿は両評価機とも画像面積６％の画像パターンを使用し、２２〜２４（℃）／５８〜６５（％ＲＨ）環境にて通紙ランニングを行った。
評価は初期、１００枚後（摩擦係数測定のみ）、５万枚後に行った。
【０２９６】
（実施例１〜８）
評価用の感光体として、表１に記載のＮｏ．４（実施例１、２）、Ｎｏ．６（実施例３、４）、Ｎｏ．７（実施例５、６）、Ｎｏ．８（実施例７、８）の４サンプル、電子写真複写機（イマジオＭＦ２２００）を用意した。帯電には接触帯電装置用の帯電部材を使用し、帯電部材に印加する電圧条件は直流電圧を−６２８Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。現像バイアスは−５００Ｖに設定した。画像部電位は−９０Ｖ〜−１０５Ｖで有ったため、コントラスト電位は４１０〜３９５Ｖと画像形成には充分な電位差が確保された。
【０２９７】
これらの感光体をＪＩＳ−Ａ硬度８７度に調整して作製された厚み１ｍｍのクリーニングブレード［タイプ２−１］を搭載し、感光体に対する当接圧が２３．５ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。クリーニングブレードはネジ止めを行うことにより、自動的に接地状態となる。
【０２９８】
トナーには（１）平均円形度０．９２２、平均粒径６．３μｍ、最小粒径３．２μｍ、（２）平均円形度０．９３、平均粒径７．５μｍ、最小粒径４．１μｍの２種類の粉砕型のブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とし、評価枚数は５万枚とした。
【０２９９】
これらの評価結果を表２に示す。
【０３００】
本発明のクリーニングブレードでは、Ｎｏ．４のフィラーが分散されていない感光体のみ、画像に影響ない程度の僅かなクリーニング不良が生じたが、それ以外の感光体ではトナーが充分に堰き止められた為、感光体の表面粗度の悪化は小さかった。そのため、トナー抜け現象は殆ど無く、良好な結果を示した。画像の荒れが少ないために、画像品質良好で、表には記載していないが、解像度は小粒径トナーを使用している事も有り、いずれも７．１〜８．０（本／ｍｍ）を示し、１ドット再現性も良好であった。
Ｎｏ．４でクリーニング不良が起こったのは、表面粗度の大きさによるものではなく、感光体の摩擦係数が０．６２以上と大きいため、補強しているにも関わらず、ブレードエッジがトナー抜けが生じる程度に歪み（３μｍ前後）を生じた為と思われる。またＮｏ．４で判定が△であったのは、摩耗量が多いためであるが、画像品質上では特に問題は確認されなかった。
【０３０１】
【表２】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３０２】
（実施例９〜１４）
評価用の感光体として、表１に記載のＮｏ．４（実施例９、１０）、Ｎｏ．６（実施例１１、１２）、Ｎｏ．８（実施例１３、１４）の３サンプル、電子写真複写機（イマジオＭＦ２２００）を用意した。帯電条件は非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は直流電圧を−６３５Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。
これらの感光体をＪＩＳ−Ａ硬度８７度に調整して作製された厚み２．８ｍｍのナイフ状エッジのクリーニングブレード［タイプ１］を搭載し、感光体に対する当接圧が２２．０ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。クリーニングブレードはネジ止めを行うことにより、自動的に接地状態となる構造である。
【０３０３】
トナーには（１）平均円形度０．９２２、平均粒径６．３μｍ、最小粒径３．２μｍ、（２）平均円形度０．９３、平均粒径７．５μｍ、最小粒径４．１μｍ、２種類の粉砕型のブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とした。
【０３０４】
これらの評価結果を表３に示す。
感光体に当接する部位の形状がナイフエッジ状のクリーニングブレードを使用した場合、トナーの堰き止めはほぼ充分に行われた。そのため、感光体の表面にはブレードによる摺擦傷が生じただけで、局部的に表面粗度Ｒｙが大きくなる事はなく、クリーニング不良は５万枚後でも問題ないレベルに抑えられた。
なお、Ｎｏ．４のサンプルの判定が△となったのは、摩耗が多いためであり、画像品質的には５万枚時点では全く問題なく、摩耗がほぼ平均的であるために、Ｒｙは小さく、トナー抜けは皆無であった。
Ｎｏ．８のサンプルで△を付したものは文字画像に僅かに文字太りが見られたが、実用的には殆ど問題ないレベルであった。
【０３０５】
【表３】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３０６】
（比較例１〜６）
評価用の感光体として、表１に記載のＮｏ．７（比較例１、２）、Ｎｏ．８（比較例３、４）、Ｎｏ．９（比較例５、６）の３サンプル、電子写真複写機（リコー社製　イマジオＭＦ２２００）を用意した。帯電には非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は直流電圧を−６３５Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。
【０３０７】
これらの感光体をＪＩＳ−Ａ硬度７７度のポリウレタンゴムで作製されたクリーニングブレード［タイプ３］を搭載し、感光体に対する当接圧が２３．５ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。ブレードには導電処理は行われていない。
【０３０８】
トナーには（１）平均円形度０．９１４、平均粒径５．２μｍ、最小粒径２．８μｍ、（２）平均円形度０．９２２、平均粒径６．３μｍ、最小粒径３．２μｍの２種類の粉砕型ブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とした。
【０３０９】
結果を表４に示す。
ブレードに補強が無く、トナー粒径が３μｍ前後の小粒径の場合、感光体表層の摩擦係数が高いために、ブレードの感光体に当接するエッジ部が歪みを起こしやすいことと、トナー抜けが起こっているために、感光体表面が荒れて、トナー抜けが生じやすい状況が生まれた為に、更に表面粗度Ｒｙが大きくなり、クリーニング性不良、画像品質不良によって△又は×の判定となった。特に電荷輸送層に添加するフィラーの粒径が１μｍの場合は、数字的にはＮｏ．８のサンプルに近い値であるが、全体的に表面凹凸の荒れが目立ち、ブレードの歪みが起こりやすい状況にあった事が×の一要因と推測される。
【０３１０】
【表４】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３１１】
（実施例１５〜２２）
評価用の感光体として、表１に記載のＮｏ．６（実施例１５、１６）、Ｎｏ．７（実施例１７、１８）、Ｎｏ．８（実施例１９、２０）、Ｎｏ．９（実施例２１、２２）の４サンプルと電子写真複写機（イマジオＭＦ２２００）を用意した。帯電には非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は直流電圧を−６３５Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。
【０３１２】
これらの感光体を硬度８７度に調整して作製されたクリーニングブレード［タイプ１］を搭載し、感光体に対する当接圧が２２．０ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。クリーニングブレードはネジ止めを行うことにより、自動的に接地状態となる構造である。
【０３１３】
トナーには（１）平均円形度０．９８７、平均粒径５．６μｍ、最小粒径４．５μｍ、（２）平均円形度０．９９２、平均粒径３．８μｍ、最小粒径３．１μｍの２種類の重合法によるブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とした。
これらの評価結果を表５に示す。
トナーを円形度の大きい重合トナーに変更した場合に於いても良好なクリーニング性を示した。これは特にクリーニングブレードのエッジの変形が殆ど無く、また、トナーを感光体に押しつける部位が無いために、ブレードの浮き上がりが無いために隙間が生じなかった為と推測される。その結果、感光層表面粗度の暴れも比較的抑えられ、画像品質は良好であった。特に解像度は粉砕トナーに比べ、シャープ性が良く、文字エッジの揺らぎも殆ど見られず、解像度は７．１〜９．０本／ｍｍの高解像度が得られた。また、ライン画像の交差する箇所での文字抜けが僅かに有ったものの、実用上は問題にならない程度に良好な結果であった。
【０３１４】
【表５】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３１５】
（比較例７〜１２）
評価用の感光体として、表１に記載のＮｏ．６（比較例７、８）、Ｎｏ．７（比較例９、１０）、Ｎｏ．８（比較例１１、１２）の３サンプルと電子写真複写機（イマジオＭＦ２２００）を用意した。帯電には非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は直流電圧を−６３５Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。
【０３１６】
これらの感光体をＪＩＳ−Ａ硬度７１度のポリウレタンゴムで作製されたクリーニングブレード［タイプ２−１］を搭載し、感光体に対する当接圧が２３．５ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。
【０３１７】
トナーには（１）平均円形度０．９９３、平均粒径５．６μｍ、最小粒径４．５μｍ、（２）平均円形度０．９８７、平均粒径３．８μｍ、最小粒径３．１μｍの２種類の重合法によるブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とした。
【０３１８】
これらの評価結果を表６に示す。
ＪＩＳ−Ａ硬度が７１度のクリーニングブレードと、重合法で作製した平均円形度が大きいトナーとの組み合わせでは、トナーのクリーニング性は全く不良で、帯電部材がトナー汚染を受け、画像品質はムラの多いものとなった。また地肌が薄く汚れる結果となった。
トナー抜けは、特には最小粒径が３．３μｍのトナーを使用した場合に多く、表面粗度Ｒｙが大きい場合にクリーニング不良が多くなる傾向が見られた。
【０３１９】
【表６】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３２０】
（実施例２３〜２６）
評価用の感光体として、表１に記載のＮｏ．７（実施例２３）、Ｎｏ．１１（実施例２４）、Ｎｏ．１２（実施例２５）、Ｎｏ．１３（実施例２６）の４サンプル、電子写真複写機（イマジオＭＦ２２００）を用意した。帯電条件は非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は交流電圧は１５００Ｖ／１３５０Ｈｚ一定として、直流電圧を調整する事によって、感光体の表面電位を設定した。
感光体に印加する現像装置位置での感光体の表面電位はＮｏ．７、Ｎｏ．１２およびＮｏ．１３では−６００Ｖ、Ｎｏ．１１は−４５０Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。なお現像バイアスはＮｏ．１１については−３５０Ｖ、Ｎｏ．７、Ｎｏ．１２およびＮｏ．１３に付いては−５００Ｖに設定した。Ｎｏ．１１の表面電位が低いのは、膜厚が薄いためである。画像部電位は−６０Ｖ〜−９０Ｖで有った。
【０３２１】
これらの感光体をＪＩＳ−Ａ硬度７７度に調整して作製された厚み２ｍｍのクリーニングブレード［タイプ２−１］を搭載し、感光体に対する当接圧が２３．５ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。クリーニングブレードはネジ止めを行うことにより、自動的に接地状態となる。
【０３２２】
トナーには平均円形度０．９９３、平均粒径５．６μｍ、最小粒径４．５μｍの重合法によるブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、トナーへの潤滑剤は未添加とした。
【０３２３】
これらの評価結果を表７に示す。
トナーのクリーニング性に関しては感光層が薄い場合（１０．５μｍ）も厚い場合（３６．８μｍ）も、いずれも良好な結果であった。画像濃度は感光体Ｎｏ．７では１．３５〜１．４と若干薄目となったが、その他の感光体では１．５以上を示し良好であった。また、Ｎｏ．１３の感光体では膜厚が厚かった為に、文字につぶれが見られ、解像度は６．３〜７．１（本／ｍｍ）と小径トナーを使用している割には、若干では有るが解像度が低めに出た。
Ｎｏ．７の様な画像濃度が低い場合には、トナー濃度を上げて補うことが出来るが、余り上げると、地肌汚れを招く恐れが有る。１０μｍの感光層膜厚が限度に近いレベルと判断される。３０．５μｍではなお実用性が有るが、これ以上では問題（残留電位の上昇に伴う画像濃度低下、解像度低下）が出る可能性がある。
【０３２４】
【表７】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３２５】
（実施例２７〜３２）
評価用の感光体として、表１に記載のＮｏ．１５（実施例２７、２８）、Ｎｏ．１６（実施例２９、３０）、Ｎｏ．１７（実施例３１、３２）のフィラー量が１０〜４０重量％添加された感光体３サンプルと電子写真複写機（イマジオＭＦ２２００）を用意した。帯電には非接触帯電装置用の帯電部材−１を使用し、帯電部材に印加する電圧条件は直流電圧−６３５Ｖ、交流電圧を１５００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６００Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。
【０３２６】
これらの感光体をＪＩＳ−Ａ硬度８１度のポリウレタンゴムで作製されたクリーニングブレード［タイプ１］を搭載し、感光体に対する当接圧が２２．０ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。
【０３２７】
トナーには（１）平均円形度０．９９３、平均粒径５．６μｍ、最小粒径４．５μｍ、（２）平均円形度０．９８７、平均粒径３．８μｍ、最小粒径３．３μｍの２種類の重合法によるブラックトナーを使用し、キャリアに対して６．５重量％を混合した。なお、感光体の表面摩擦係数を低減する為の潤滑剤として、平均粒径０．３μｍのステアリン酸亜鉛微粉末をトナーに対して０．０３重量％添加した。
【０３２８】
評価結果を表８に示す。
潤滑剤をトナー中に添加することによって、感光体の表面摩擦係数が０．３〜０．４５の間で良好にコントロールされた。その結果、クリーニングブレードと感光体間の摩擦抵抗が大幅にダウンしたため、クリーニングブレードのエッジの歪みは皆無になり、円形度の大きいトナーでも充分にクリーニングが行われた。その結果、異常画像の発生もなく、解像度も４０重量％の感光体（Ｎｏ．１７）では７．１本／ｍｍであったが、他の２本は８．０〜９．０（本／ｍｍ）と極めて良好な結果であった。
【０３２９】
【表８】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３３０】
（比較例１３〜１６）
感光体をＮｏ．１４（フィラー添加量５重量％）、Ｎｏ．１８（フィラー添加量５０重量％）に変え、クリーニングブレードを［タイプ３］にした以外は、実施例１５〜実施例２２に同様の条件で評価を実施した。結果を表９に示す。
【０３３１】
フィラー量が５重量％分散のＮｏ．１４の感光体では、ブレードに補強が無いために、感光体に当接したエッジ部が潰れ易くなり、歪みを生じた部位よりトナーの潜り込みが起こった。その結果、トナー抜けが起こり、初期よりクリーニング不良が数カ所で確認された。
一方、フィラー量が５０重量％のＮｏ．１８の感光体では、最小粒径が３．１μｍのトナーを使用した場合に補強の無いブレードと、表面粗度が大きい事との相乗効果により、トナー抜けが連続的に起こった。また、添加量が多いために、解像性が甘く、ムラの多い、解像度の低い（５．６〜７．１本／ｍｍ）画像品質となった。
【０３３２】
【表９】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３３３】
（実施例３３、３４）
評価用の感光体として、表１に記載のＮｏ．６（実施例３３）、Ｎｏ．８（実施例３４）の感光体と電子写真複写機（イプシオカラー８０００機　リコー製）を用意した。帯電には非接触帯電装置用の帯電部材２−２を使用し、帯電部材に印加する電圧条件は直流電圧−６９５Ｖ、交流電圧を１８００Ｖ／１３５０Ｈｚとした。
感光体に印加する現像装置位置での感光体の表面電位はいずれも−６８０Ｖになる様に直流電圧を微調整し、５万枚の通紙ランニングを行った。画像部電位は−８０Ｖ、現像バイアスは−５６０Ｖに設定した。
【０３３４】
これらの感光体をＪＩＳ−Ａ硬度７７度のポリウレタンゴムで作製されたクリーニングブレード［タイプ２−２］を搭載し、感光体に対する当接圧が２２ｇ／ｃｍになる様に、評価用の電子写真複写機の感光体ユニットにセットした。
【０３３５】
トナーには乳化重合法による平均円形度０．９９１、平均粒径５．１μｍ、最小粒径３．６μｍのマゼンタトナー（Ｍ）、平均円形度０．９９３、平均粒径５．１μｍ、最小粒径４．７μｍのシアントナー（Ｃ）、平均円形度０．９９１、平均粒径５．５μｍ、最小粒径４．２μｍのイエロートナー（Ｙ）、平均円形度０．９９３、平均粒径５．６μｍ、最小粒径４．５μｍのブラックトナー（Ｂｋ）を使用し、キャリア（ＦＰＣ−３００ＬＣ）に対して５重量％を混合した。なお、トナー中に潤滑剤として０．３μｍ径のステアリン酸亜鉛粉末がトナーに対して０．０３重量％添加されている。
【０３３６】
評価結果を表１０に示す。
クリーニング部材はトナーのみならず、紙粉等をクリーニングブレードで問題なく阻止出来たため、感光体にはブレードによる摺擦傷が発生しただけで、深いスクラッチを生じる事は無かった。このため、画像品質良好で、解像度も縦、横とも８．０本／ｍｍと良好であった。
【０３３７】
【表１０】

（注）○、△、×の判定：クリーニング性、画像品質、摩耗量から判定して、
○：問題なし、
△：問題性小（但し、５万枚以上で問題になる可能性がある）、
×：実用上問題有り
表中μは摩擦係数を表し、添え字の０、０．１Ｋ、５０Ｋは評価時の通紙枚数０（初期）、１００枚、５万枚を夫々示す。
【０３３８】
【発明の効果】
請求項１に記載の構成によって、
画像形成装置内に搭載された感光体はコピーの度に表面粗度最大山高さＲｐ、最大谷深さＲｖが大きくなる。クリーニング不良はＲｐとＲｖの和Ｒｙが使用するトナーの最小粒径より大きくなった場合に起こり易く成る傾向があった。したがって、Ｒｙ＞Ｄとし、且つ、クリーニングブレードをカウンター当接にする事により、効率的にトナー抜けを抑制することが可能である。また、クリーニングに使用されるブレードには、感光体と当接するエッジ部が、少なくともＪＩＳ−Ａ硬度で７５〜９０度の硬度を持ち、形状がナイフエッジ状若しくは、補強板を持つ短冊状のゴム状弾性体を使用することによって、感光体と当接するエッジのねじれや歪みが起こりにくく成るため、感光体に残留するトナーをクリヤーに除去することが可能となる。このため、感光層表面にはブレードによる摺擦傷のみとなり、トナーフィルミングも生じにくい為、感光層の摩耗が抑制される。
そのことにより、画像品質の劣化が少なくなり、高解像度で、シャープ性良好な画像が維持可能である。
【０３３９】
２）請求項２の構成によって、
トナーの流入する上流側のブレードの片側全長さに亘って、低抵抗物質を塗工し、設置することにより、トナーの流入する側を電位的に０Ｖにする。この事によって、トナーが静電的にクリーニングブレード壁面に付着するのを少なくし、トナーのクリーニングブレードからの離れを起こしやすくなるため、クリーニング不良を防止する事が出来る。
【０３４０】
３）請求項３の構成によって、
現像剤中に投入するトナーの最小粒径を３μｍとすることにより、Ｒｙに起因して生じる、トナー抜け（クリーニング不）を抑止する事が可能となる。また、３μｍ以上のトナーを使用することによって、飛散に伴う健康被害を最小限に食い留められる。
【０３４１】
４）請求項４、５の構成によって、
球形トナーの平均円形度を０．９４０〜０．９９５のトナーを使用した場合にも画像パターンに忠実な現像が可能となるため、解像度、シャープ性が良好になり、また、２代目画像に品質劣化も抑制される。クリーニング性に関しては極めて良好な状態で維持することが出来、総体的に画像品質の大きな向上が可能である。
【０３４２】
５）請求項６の構成によって、
感光層の総膜厚ｔを１０μｍ≦ｔ≦３０μｍとすることにより、画像形成に必要な帯電々位が保証でき、また、解像度、シャープ性を良好に維持する事が可能である。また、フィラー分散電荷輸送層ｔ_２をｔ_２≦８μｍとする事によって、残留電位に伴う、画像劣化を抑制する事が可能である。
【０３４３】
６）請求項７の構成によって
電荷輸送層中にフィラーを分散して、フィラー分散電荷輸送層にする場合に、添加するフィラーの平均粒径を０．２μｍ〜０．７μｍのアルミナを、フィラー分散電荷輸送層の１０重量％〜４０重量％にする事により、耐摩耗性を向上させると共に、ブレードの感光層への食い込みを抑制し、ブレードエッジ部が歪み、ねじれを起こしにくいようにする。また、クリーニングブレードと感光体間の摩擦抵抗の増大を抑えることによって、ブレードエッジの歪み、ねじれを少なくする。この事により、トナーのクリーニング不良を改善することが出来る。
【０３４４】
７）請求項８、９の構成によって、
トナーのクリーニング不良は、感光体とクリーニングブレードの摩擦抵抗が高くなると、クリーニングブレードエッジにねじれや歪みが起こし易くなり、感光体間に僅かな隙間が形成された事によってもおこる。この現象を改善するには、感光体の表面摩擦係数を下げる事によって効果的に行われる。低減化する手段としては、ポリテトラフルオロエチレンか、ステアリン酸亜鉛の微粒子を感光体に微量付与し、感光層が適度に摩耗する程度の０．３〜０．４５の間に摩擦係数（オイラーベルト方式による）に維持する。低摩擦係数と、本発明のブレードとの併用により、トナーのクリーニング性が更に向上し、トナーのクリーニング不良が抑制され、安定したクリーニング性が維持可能である。
その結果、感光体の高耐久化が図られ、且つ、画像劣化のない高解像度の、シャープ性良好な作像性を維持することが出来る。また、摩擦係数を下げることによって感光体のブレード鳴きも抑制する事が出来る。
【０３４５】
８）請求項１０の構成によって、
本発明の感光体、クリーニングブレードはタンデム方式のフルカラー画像形成装置にも適用でき、良好なトナークリーニング性が行われるため、明度の高いカラーが再現できる。
【０３４６】
９）請求項１１の構成によって、
本発明の感光体、クリーニングブレードを使用した画像形成方法では、トナーの様な微粒子を殆どブレードの入口で堰き止め、帯電部材への流出が無いため、感光体表面はブレードによる摺擦傷のみに留まるため、フィルミングの発生も少なくなり、スクラッチのような深い傷の発生もない。したがって感光層表面は清浄な状態に維持されるため、コントラスト良好、高解像度均一作像性が得られ、また、感光体の長寿命化を図る事が出来る。
【図面の簡単な説明】
【図１】表面粗度Ｒｐ（最大山高さ）、Ｒｖ（最大谷深さ）、Ｒｙ（Ｒｐ＋Ｒｖ）を説明する図である。
【図２】本発明に使用される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は鋭角にシャープカットした形状の弾性体から成るクリーニングブレードを使用し、感光体内部には制振部材が内蔵された図を示す。
【図３】感光体表面にブラシを介し、潤滑剤を塗布する潤滑剤塗布装置を設置した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４】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５】プロセスユニットの一例を示す。図では感光体、帯電装置、クリーニング装置、転写装置が一体的に組み込まれた構成である。
【図６】本発明に使用する基本的な電子写真感光体の構成を説明する概略図である。下引き層（若しくは中間層）、電荷発生層、電荷輸送層（フィラー非分散電荷輸送層）の順に構成される。
【図７】本発明に使用する電子写真感光体の構成を説明する概略図である。下引き層（若しくは中間層）、電荷発生層、電荷輸送層の順に構成され、電荷輸送層は無機フィラーを分散していないフィラー非分散電荷輸送層と、無機フィラーを分散した無機フィラー分散電荷輸送層から構成される。
【図８】表面粗度を測定した一例を示す。フィラー分散電荷輸送層に０．３μｍのアルミナフィラーを２５重量％添加した感光体で、初期状態の表面粗度を示す。掃引幅は２．４ｍｍである。
【図９】図８と同じ感光体を１万５千枚通紙ランニングを行った後の表面粗度を示す。掃引幅は２．４ｍｍで、Ｒｐが増加しているのが判る。
【図１０】感光体のＲｙの大きさによって、ブレード下からトナーが抜け出る場合と、抜けでない場合の状態を説明した図である。
【図１１】硬度の低い短冊状のクリーニングブレードを使用したときに、球形トナーが抜け出る状態を説明する図である。フィラー分散電荷輸送層の表面粗度の無機フィラー（αアルミナ）平均一次粒径依存性を示すグラフ例である。
【図１２】ナイフエッジ状の形状を有するクリーニングブレード、金属板で補強した短冊状のクリーニングブレードの形状を説明する図である。
【図１３】ナイフエッジ状の形状を有するクリーニングブレード、金属板で補強した短冊状のクリーニングブレードの形状を説明する図である。
【図１４】ナイフエッジ状の形状を有するクリーニングブレード、金属板で補強した短冊状のクリーニングブレードの寸法、角度を示す図である。
【図１５】ナイフエッジ状の形状を有するクリーニングブレード、金属板で補強した短冊状のクリーニングブレードの寸法、角度を示す図である。
【図１６】クリーニングブレードの当接角度を示す説明図である。
【図１７】クリーニングブレードの当接角度を示す説明図である。
【図１８】金型成形で製造したクリーニングブレードの感光体との当接面のバリをカットする状況を説明する概略図である。
【図１９】本発明のクリーニングブレード（ナイフエッジ状）によるトナークリーニングの状態を説明する模式図である。
【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：クリーニングブレード
８：定着装置
９：コピー用紙
２００：潤滑剤付与装置
２０１：潤滑剤
２０２：潤滑剤付与ブラシ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having means for satisfactorily cleaning residual powder such as toner on the surface of an electrophotographic photoreceptor, and an image forming method using the apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus using an indirect electrophotographic method such as a facsimile, a laser beam printer, and an electrophotographic copying machine, a photosensitive member, a charging device, an image exposing device, a developing device, a transfer device, a separating device, a cleaning device, and a static eliminator , And a fixing device are arranged, and an image is formed.
[0003]
In this image formation, the photoreceptor removes residual toner in a cleaning step after a toner image transfer step, and is thereafter repeatedly used for image formation. On the other hand, a fur brush, a magnetic brush, a blade, or the like is used as the cleaning means, but a blade is mainly used in terms of performance, configuration, and the like. As a member of the blade, a plate-like rubber or an elastic body is generally used.
[0004]
Photoreceptors used for image formation include zinc oxide (ZnO), cadmium sulfide (CdS), cadmium selenide (CdSe), and amorphous selenium (a-Se, a-Se-Te, a-As). ₂ Se ₃ Etc.), amorphous silicon type (a-Si: H), etc., but in recent years, organic photoreceptors having many advantages such as easy production, high sensitivity design, low cost, and no pollution are mainly used. Is done.
[0005]
The organic photoreceptor includes a single-layer type in which a photosensitive layer is integrally formed with functions of a charge generating material and a charge transporting material, and a function-separated type in which a photosensitive layer has a two-layered structure of a charge generating layer and a charge transporting layer. The body is used in the mainstream. A general function-separated type organic photoreceptor has a configuration in which a charge generation layer is formed directly on a conductive support or through an undercoat layer (or an intermediate layer), and then a resin layer containing a charge transport material (charge transport layer). Layer) is formed. For the charge generation layer, any of an inorganic material and an organic material can be used without limitation.
[0006]
On the other hand, as the binder resin material constituting the charge transport layer, a polycarbonate resin material (including A type, C type, and Z type) having high resistance, high transparency, and little polarity dependency is preferably used. Is done. However, the photosensitive layer using a polycarbonate resin has a Vickers hardness of 10 to 30 kg / mm. ² The pencil hardness is as small as about 2B to F and the tensile strength is also small. Further, corona products such as ozone and nitrogen oxides (NOx) generated at the time of charging tend to adhere, and the free surface energy (or coefficient of friction) decreases. Therefore, the frictional resistance with the cleaning blade is increased, so that the photoreceptor surface is unevenly worn, unevenly formed, or damaged.
[0007]
As the thickness of the photosensitive layer decreases, the capacitance increases and the charging potential decreases. For this reason, when the potential difference between the charging potential and the developing bias potential is reduced, background staining is likely to occur.
If the potential difference between the developing bias potential and the charging potential is widened to prevent background contamination on the copy, the potential difference between the developing bias potential and the image portion potential is inevitably reduced. Become. From these facts, the durability of the organic photoreceptor is as short as about 50,000 to 80,000.
Due to the low number of durable sheets, a user who has a large number of copies frequently exchanges the photoconductor and members related thereto, which is a problem.
[0008]
However, the factors that affect the endurance number are not limited to the cleaning blade, but the image area of the original, the rubbing by the developer, the pressing of the toner, carrier, and paper powder by the cleaning member, and the corona generation that occurs during the above-described charging. There are things. As the photosensitive layer wears, the capacitance increases, and the charging potential decreases. Therefore, the margin between the charging potential and the developing bias potential is reduced, and the possibility of background contamination is increased.
[0009]
In a quadruple tandem type color copier, the wear of the four photoconductors varies depending on the color of the original, the image area, the amount of the developer fed, the amount of toner, and the like, in addition to the background contamination, so that the color uniformity is improved. And color reproducibility.
[0010]
Improving the abrasion 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 photoconductor. Techniques for increasing the durability of the photoreceptor include a method of forming a wear-resistant thin film on the surface of the photoreceptor, a method of forming the photosensitive layer with a wear-resistant photosensitive material, and making the outermost surface of the photosensitive layer wear-resistant. There are methods, etc.
Here, a conventionally known technique for improving the durability of the photoconductor will be described.
[0011]
(1) JP-A-01-092756 (Patent Document 1), JP-A-02-079047 (Patent Document 2), JP-A-04-066954 (Patent Document 3), and the like disclose vapor deposition on a photosensitive layer. , Using a dry film forming method such as a CVD method, has a high transmittance in the visible light to infrared light region, and has a volume resistivity (10 ¹¹ -10 ¹⁴ A-SiC layer (amorphous silicon carbide layer), aC film (amorphous carbon layer), DLC film (Diamond Like)
It describes that a uniform thin film such as a Carbon layer is formed.
The film hardness (Knoop hardness) of the above thin film is 500 to 2000 (kg / mm). ² ), Which is about 20 to 100 times larger than the organic material, is an effective means for increasing the durability of the photoreceptor, and achieves a durability of about 500,000 to 1,000,000 sheets even with a thin film of about 2 μm. It is possible to do.
[0012]
However, if a low-resistance corona product such as ozone or nitrogen oxide (NOx), which is a low-resistance substance, adheres to an a-SiC film, an aC film, or a DLC film, it is strongly adsorbed. There is a problem that the resolution is reduced when the number of sheets is about one, and the image flow occurs when the number is about 100.
Further, when an a-SiC film, an aC film, a DLC film, etc. are formed on a soft resin layer such as an organic photosensitive layer, pinholes and peeling occur due to the pressure contact of the blade and the action of ozone products. However, the roller charging method has problems such as easy charging unevenness, and has not been put to practical use.
[0013]
(2) JP-A-06-0352220 (Patent Document 4), JP-A-08-234469 (Patent Document 5) and the like disclose zinc oxide, titanium oxide, tin oxide, antimony indium oxide, bismuth oxide, and tin oxide. It describes that the photosensitive layer is composed of a photosensitive layer in which conductive fine particles such as doped indium oxide are dispersed.
[0014]
By dispersing an appropriate amount of high-hardness conductive fine particles in the photosensitive layer, it is possible to improve the abrasion resistance. The use of low-resistance fine particles is effective for charge injection charging.However, when the hazardous contact charging method is used, image flow is likely to occur, and it is possible to achieve both resistance to image quality deterioration. difficult.
[0015]
(3) JP-A-08-123053 (Patent Document 6) discloses inorganic compound particles of 0.02 to 5 μm (preferably 0.07 to 2.0 μm), for example, silica, aluminum oxide, zinc oxide, and nitride. It describes that the photosensitive layer contains a metal oxide such as aluminum, a metal sulfide, a metal nitride, and a butadiene-based charge transport material.
This means can improve the abrasion resistance and secure the charging ability by dispersing high-resistance inorganic compound particles other than silica in the photosensitive layer. By incorporating a butadiene-based charge transporting material in the photosensitive layer, the mobility of charges can be maintained in the same manner as in the charge transporting layer.
[0016]
However, since trap sites are easily formed between the particles and the binder resin, the residual potential is accumulated by repeated use, and light attenuation is deteriorated due to repeated use, and the image density may gradually decrease and image unevenness may occur. . Also, when a filler having a large particle diameter is used, the sharpness of a line image is reduced. On the other hand, the surface roughness of the photoconductor is increased, and the difference between the maximum value and the minimum value is larger than the particle diameter of the toner. Cleaning failure. Further, there arises a problem that the edge of the cleaning blade is easily deformed, and cleaning failure of toner and corona products is easily caused.
In addition, when silica is used, the oxidizing effect of ozone causes a rapid decrease in the resistance of the photosensitive layer, and even in a normal humidity environment of about 60% RH, image flow occurs. A heat source for heating to about 55 ° C. is essential.
[0017]
(4) Japanese Patent Application Laid-Open No. 08-234455 (Patent Document 7) discloses that a charge-transporting layer having a thickness of 12 μm or less includes silicone resin, phenol resin, SiO 2 having a particle size of 1 to 3 μm. ₂ (Silica), Al ₂ O ₃ (Alumina), TiO ₂ (Titanium oxide) and a photosensitive layer in which ZnO (zinc oxide) is dispersed.
[0018]
This means is to achieve high abrasion resistance by using a filler having a large particle diameter.However, since the particle diameter of the particles is large, the surface roughness of the surface layer of the photoreceptor becomes large, and the sharpness of the image edge is reduced. Lacks. Further, when the blade cleaning method is used, the edge is distorted, the toner is missing, and the image quality of the copy paper is likely to be reduced and the background is likely to be stained. In addition, there are insufficient points such as a lack of a blade edge and an inability to maintain the durability of the cleaning blade.
[0019]
(5) JP-A-08-146641 (Patent Document 8) discloses that one or two types of inorganic compound fine particles such as titanium oxide, aluminum oxide, and silicon oxide having an average particle diameter of 0.02 to 0.5 μm are used. It describes that the photosensitive layer is composed of a photosensitive layer dispersed in a polycarbonate resin.
[0020]
This means is almost the same as the content described in the above (3), but since the particles having a small particle diameter are used, the deterioration of the image quality due to the particles is small. However, in a region where the particle size is small (for example, 0.1 μm or less), the effect of addition is difficult to be exhibited, so that the improvement in wear resistance is low, and the durability is hardly increased.
[0021]
(6) Japanese Patent Application Laid-Open No. 08-248663 (Patent Document 9) discloses a photosensitive material having a surface roughness of 0.1 to 0.5 μm formed on a conductive support having a surface roughness of 0.01 μm to 2 μm. It describes that inorganic fine particles (hydrophobized silica) having an average particle size of 0.05 to 0.5 μm are dispersed in the layer over a thickness of 0.05 to 15 μm.
This means is to increase the durability and to prevent the degradation of resolution and the image deletion caused by the adhesion of contaminants such as corona products by subjecting the dispersed silica particles to hydrophobic treatment.
[0022]
However, although the effect of repelling water droplets (large contact angle) is exhibited by making the inorganic fine particles hydrophobic, the adhesion of the corona product cannot be prevented, so that the image deletion cannot be prevented. In addition, the inorganic fine particles that have been subjected to the hydrophobic treatment that has come out of the surface of the photosensitive layer are rubbed by a blade or the like, and the coating is shaved, and the resistance of silica is reduced by the action of ozone. Almost impossible.
[0023]
As described above, a high-quality image cannot be stably formed by an image forming method using only a photoreceptor having high abrasion resistance by adding particles to the surface in order to increase durability. The “high-quality image” here is an image having a high resolution, sharpness, a dot pattern resolved as a dot pattern, and no background contamination.
[0024]
An image forming method is disclosed in Japanese Patent Application Laid-Open No. H11-212412, in which the surface roughness of the photoreceptor is 10 points average roughness (Rz) of 0.2 to 2.0 μm and an elastic blade is brought into contact with the photoreceptor surface in the counter direction. (Patent Document 10).
Here, the surface roughness of the photoreceptor is important for maintaining image quality. The surface roughness is influenced by applying an object having a grain size to the photosensitive layer or forming a dispersed thin film. Further, as the particle size increases, the surface roughness increases.
[0025]
Items for evaluating the surface roughness include a 10-point average roughness (Rz). _JIS ), The maximum peak height (Rp), the maximum valley depth (Rv), the average height (Rc), and the like. _JIS ), The maximum peak height (Rp) and the maximum valley depth (Rv) are more important. That is, since the above-described 10-point average roughness is expressed as an average value, it cannot be determined whether or not the toner is removed.
[0026]
In the case where the maximum peak height Rp and the maximum valley depth Rv are adjacent to each other on the surface of the photoconductor, if the sum Ry of the peaks and valleys is larger than the toner particle diameter, the toner can easily pass under the blade. I can do it.
If the maximum peak height Rp and the maximum valley depth Rv are larger than the toner particle diameter, there is a possibility that the toner will come out. However, if Rp or Rv alone exceeds the toner diameter, the system condition becomes poor and the carrier is It can be said that there is almost no exception except in special cases where it adheres to the surface and is suppressed by the blade, causing deep scratches.
[0027]
If the edge of the cleaning blade that contacts the photoconductor is locally distorted due to the influence of the maximum peak height or maximum valley depth, the gap between the blade and the photoconductor expands, and the blade edge gradually increases. Chipping, resulting in permanent cleaning failure. Therefore, the charging member is contaminated, and the copy paper is stained.
Also, as the surface roughness increases, the charge density on the surface of the photoreceptor becomes scattered, and the adhesion of the copy paper at the time of transfer is affected, so that the image lacks sharpness of character edges. . In addition, corona products accumulate between the particles, resulting in poor cleaning, which causes image deletion.
[0028]
In order to obtain good image quality, it is desirable that the surface roughness of the photoreceptor be small, but if the surface roughness is too small, the cleaning blade will be in intimate contact with the photoreceptor, and the friction coefficient between the photoreceptor and the cleaning blade will be low. Will be higher. For this reason, the blade edge is dragged and deformed by the photoconductor, which also causes a cleaning failure. Therefore, it is desirable that the gap between the blade and the photoconductor is sufficiently small to a certain extent rather than completely adhered. This relationship needs to be maintained after the photoreceptor has been used.
[0029]
However, there are concaves and convexes on the photoreceptor surface. When the concave (= maximum valley depth: Rv) or convex (= maximum peak height: Rp), or the width of the unevenness (Rp + Rv = Ry) is larger than the toner particle diameter, the toner always comes off, and the unevenness is the toner. Even when the blade is twisted and a gap is formed between the photoconductors, the toner may be temporarily removed. Therefore, there is a method in which Rp and Rv are predicted in advance, and Rz is set lower and Rz is specified. However, when toner is missing in Rz, it cannot be determined whether the toner diameter is larger or smaller. Is smaller than the fluctuations of Rv and Rp, and is not sufficient to be specified by Rz (10-point average roughness).
[0030]
In an image forming apparatus, a one-component developer or a two-component developer in which toner and a carrier are mixed in an appropriate amount is used to visualize an electrostatic latent image formed by charging and image exposure. . Development methods include a magnet brush development method, a spray development method, a cascade development method, a flying development method, and the like, and the mainstream is a magnet brush development method.
[0031]
As a carrier used for a two-component developer, a magnetic powder having a particle size of about 30 to 80 μm coated with a resin containing a charge control agent such as iron powder, ferrite, and magnetite is used. If the particle size is small, high resolution is easily obtained. However, if the particle size is too small, the carrier easily adheres to the photoreceptor, which may cause image omission or damage to the photoreceptor when transferring a toner image.
Therefore, it is necessary to select a carrier suitable for the copying system.
[0032]
On the other hand, in recent years, with the spread of color copiers, higher definition and reproducibility of images are increasingly required, and toners having an average particle size of 4 to 8 μm are mainly used (however, Since the particle size is indicated, a large number of toners having a small particle size of 4 μm or less are mixed.)
[0033]
(I) The toner production method mainly includes a pulverization method and a polymerization method.
The pulverization method is a method in which additives such as a colorant and a charge control agent are melted and kneaded in a binder polymer produced by polymerization, and the resulting mass is roughly pulverized, finely pulverized, and classified by a sieve.
Although the pulverization method has an advantage that the toner can be finely divided, the cost is likely to be high because the process is complicated.
[0034]
The toner produced by the pulverization method has an irregular shape (irregular shape). A rounding step is further added to obtain a toner for a developer, and the particle size is sieved by classification. In a commonly used toner, since the circularity of the toner is small (square), it is difficult to uniformly charge the particles, and transfer failure easily occurs. In addition, when pressed against the photoreceptor by the cleaning blade, there is a tendency that scratches easily occur.
[0035]
In addition, even if a high resolution with good sharpness is obtained in the early stage, it is difficult to maintain, and when a copy of a copy (the second or third generation copy) is printed, the resolution becomes extremely poor, and it is not practical. There are points. For this reason, toners with higher sphericity are being developed, but the cost is further increased, and conversion to polymerization is being promoted.
[0036]
(Ii) The main production methods of the polymerization method include a suspension polymerization method and an emulsion polymerization method. For example, in the case of the suspension polymerization method, it is manufactured by homogenizing additives such as a colorant and a charge control agent to a binder resin monomer, adding a dispersion medium and a dispersant, and polymerizing. Since the polymerization method has a simplified process, the production cost is lower than that of the pulverization method. In addition, there is an advantage that the particle diameters are relatively well uniform, and irregularly shaped particles are hardly produced (mostly spherical toner).
Most of the particles produced by the polymerization method have a spherical shape close to a true sphere, and have relatively uniform particle diameters. Therefore, it is easy to make charging uniform and adhere to a latent image almost faithfully. Therefore, the transfer efficiency is as high as 99% or more, high resolution can be easily obtained, and dot image reproducibility is high.
[0037]
For this reason, in recent years, there are many examples in which a toner produced by a polymerization method having many advantages is used.
The circularity of the spherical toner produced by the polymerization method is larger (0.98 to 0.998) than that of the spherical toner (about 0.91 to 0.93). There is a problem that defects easily occur.
[0038]
Conventional cleaning blades that have been used with pulverized toner up to now use a relatively soft rubber blade with a blade hardness of about 70 to 80 degrees. At the same time, the blade edge is distorted. Further, since the friction coefficient of the photoconductor is high, the tip of the blade is caught in the photoconductor and deformed. For this reason, a slight gap is generated between the blade and the photoconductor, to the extent that the toner escapes, and the toner staying on the cleaning blade passes through the gap between the blades, so-called toner loss occurs. This is especially true when the surface roughness of the photosensitive member is large due to scratching, filming, or the like.
This toner removal tends to be more severe as the spherical toner is less caught and has a larger circularity.
[0039]
In a cleaning device in which the contact pressure of the blade is set to a small value, there is a case where cleaning is hardly performed in some cases, and a photosensitive member having a softer surface layer of the photosensitive member is more difficult to perform cleaning.
[0040]
There are two methods for cleaning the toner, in which one cleaning blade is installed in a reverse rotation direction (counter) or a forward rotation direction (leading) with respect to the rotation direction of the photoconductor, but further necessary. Depending on the condition, a cleaning brush made of polyester fiber or nylon fiber is used in combination.
Since the blade cleaning method is an advantageous method for reducing the size of an image forming apparatus, it is employed in most image forming apparatuses.
[0041]
In the blade cleaning method, if the blade is installed in the counter direction with respect to the rotation direction of the photoconductor, the bite into the photoconductor increases, and the cleaning performance of the toner can be improved.
The cleaning blade is formed by cutting a rubber plate having a JIS-A hardness of about 70 to 80 degrees and a rebound resilience of about 30 to 60% into a strip having a width of 1.5 mm to 3 mm. It is used by attaching it to a support substrate.
At present, polyurethane rubber for a cleaning blade, which is generally and preferably used, easily adheres to a photosensitive member made of a polycarbonate resin, and the frictional resistance between the photosensitive member and the blade is extremely large.
[0042]
For this reason, some kind of lubricant is usually taken into the surface of the photoreceptor or applied from the outside. Once rotation starts, the toner becomes a certain amount of lubricant, so the friction coefficient is particularly reduced. As long as the photosensitive member does not use a binder resin that is difficult to perform, the photosensitive member can be rotated normally. However, since the coefficient of friction is not low enough, when the edge of the cleaning blade comes into contact with the photoconductor, the edge is pulled in the rotation direction of the photoconductor, causing the edge to be distorted and causing chatter ( Vibration) phenomenon may occur. At this time, since a slight gap is generated between the blade and the photoconductor, a phenomenon occurs in which the toner adhered to the photoconductor and powder such as paper powder slip through. Slippage of the toner causes toner filming and contamination of the charging member, resulting in poor charging and deterioration of image quality.
[0043]
Another factor that causes the toner to slip through is that the cleaning blade has a cut width of 1.5 to 3 (mm), and is deformed by being pressed and pulled by the photoconductor, the cut surface approaches the photoconductor, and the toner is removed by the blade. When the blade is lifted by being sandwiched between the photoreceptor and the normal photoreceptor, the surface layer of the photoreceptor is not durable. Edges may be distorted and uniform contact may not be possible. From this, it can be said that the surface roughness of the photosensitive layer is preferably as hard as possible and the surface roughness is as small as possible within a range that does not increase the degree of adhesion to the photosensitive member.
[0044]
Some means for cleaning the spherical toner have been proposed. For example, in Japanese Patent Application Laid-Open No. 2001-242758 (Patent Document 11), a plurality of plate-shaped cleaning blades are adhered to each other, and a blade A that is in contact with the photosensitive member is used. The problem is solved by setting the relationship between the rebound resilience B on the side not in contact with and the pressure to be 0.1 B <A and setting the pressure to 10 to 30 N / m.
In this method, plate-like blades having different rebound resiliences are adhered to each other to increase the toughness of contact with the photoreceptor, and to improve the toner's resistance to passing through.
[0045]
When the surface roughness of the photoreceptor surface layer is larger than the toner particle diameter, the toner is naturally removed. However, when the friction coefficient of the photoreceptor surface layer is high, that is, when the frictional resistance between the cleaning blade and the photoreceptor is large, the blade edge Is dragged in the rotation direction of the photoconductor, and it is inevitable that the photoconductor is distorted.
For this reason, when the surface roughness of the photoreceptor is large, there is a danger of missing toner, and blade squeal occurs. If toner loss occurs constantly, the surface roughness of the photoconductor increases, and toner loss occurs more and more.
[0046]
In Japanese Patent Application Laid-Open No. 05-265360 (Patent Document 12), a plate-shaped conductive blade is used as a cleaning member, and an AC bias and a DC voltage having the same polarity as a charge of the toner during development are applied to the blade. By doing so, cleaning defects are eliminated.
This method removes toner by applying a voltage to the blade, weakens the adhesion of the toner to the blade and the photoreceptor, and reduces the penetration of the toner under the blade. Can be expected. However, when the amount of toner flowing into the blade is large, the effect of the voltage application is small, and it is difficult to prevent the toner only by the blade.
[0047]
Japanese Patent Application Laid-Open No. 2001-321191 (Patent Document 13) uses a toner (true spherical to elliptical toner) having a shape factor SF-1 of 100 to 140 and a SF-2 of 100 to 120, and provides a counter to the photoconductor. The object is solved by setting the linear pressure of the cleaning blade in contact with the direction to be 20 g / cm to 60 g / cm.
When the toner is a true sphere, the above-mentioned contents are insufficiently cleaned, but as the toner becomes elliptical, the cleaning property is improved. Although the cleaning performance can be improved by increasing the cleaning pressure, the cleaning performance may be further deteriorated depending on the shape of the cleaning blade and the surface roughness of the photoconductor over time.
[0048]
Japanese Patent Application Laid-Open No. 2001-305776 (Patent Document 14) discloses a silicon compound having an average primary particle diameter of 5 to 500 nm (= 0.005 μm to 0.5 μm) in the surface layer of a photoreceptor using a plate-like cleaning blade. The problem is solved by including 3 to 30 parts by weight of the fine particles based on the total weight of the solid content.
The inclusion of the silicon compound fine particles having high hardness on the surface of the photosensitive layer has an effect of reducing biting of the blade and reducing frictional resistance between the blade and the photosensitive layer. As a result, the effect of improving toner slip-through is exhibited.However, when the particles are too small, there is no effect of reducing the frictional resistance. When the particles are too large, the silicon compound has a low resistance due to ozone generated during charging. In this case, the risk of image deletion increases. In addition, the frictional resistance increases, and the edge of the cleaning blade is distorted, which causes toner to be removed.
[0049]
In order to clean toner satisfactorily, the edge of the cleaning blade should not vibrate due to rotation, the edge of the blade should not be dragged by the photoconductor, and the toner would be pressed by the blade. It is important not to make room (the blade should be in line contact with the photoreceptor during driving, not in surface contact). For this purpose, it is necessary to take measures not to cause the cleaning blade to be resistant to the shape and the deformation, and also to prevent the cleaning blade from coming off. The vibration of the blade also increases the wear of the photoconductor.
Further, when the friction coefficient of the photoconductor is large, the blade is easily distorted, and the toner is easily attached to the photoconductor. Therefore, the edge of the blade floats, and a slip-through phenomenon occurs. Although a certain effect is recognized in the disclosed examples, there is still room for improvement in any of the methods, and there is a possibility that the cleaning property may be reduced by prolonged use.
[0050]
[Patent Document 1]
JP 01/092756 A
[Patent Document 2]
JP-A-02-079047
[Patent Document 3]
JP-A-04-066954
[Patent Document 4]
JP-A-06-035220
[Patent Document 5]
JP 08-234469 A
[Patent Document 6]
JP-A-08-123053
[Patent Document 7]
JP 08-234455 A
[Patent Document 8]
JP 08-146641 A
[Patent Document 9]
JP 08-248663 A
[Patent Document 10]
JP-A-11-212412
[Patent Document 11]
JP 2001-242758 A
[Patent Document 12]
JP 05-265360 A
[Patent Document 13]
JP 2001-212191 A
[Patent Document 14]
JP 2001-305776 A
[0051]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of performing good cleaning even when using a toner having a large circularity and obtaining a high-quality image, and an image forming method using the apparatus.
[0052]
[Means for Solving the Problems]
The present inventors have again examined the toner passing through the cleaning blade.
Spherical toner having a high average circularity, particularly spherical toner having a circularity of 0.98 or 0.99, is considered to be difficult to clean even if the cleaning method is a blade cleaning method installed in the counter direction. You. This cleaning failure is a phenomenon caused by toner passing through the cleaning blade. This phenomenon was observed by setting a CCD camera toward the developing unit of the experimental device manufactured for confirmation and observing the movement of the developing unit. The following was found out.
[0053]
Generally, a relatively soft elastic body having a hardness of 70 to 80 degrees is used for the blade used for the cleaning blade, and is brought into contact with the photosensitive member in the counter direction. It is confirmed that the edge portion of the cleaning blade that is in contact with the photoconductor is locally dragged along the rotation direction of the photoconductor, causing crushing and twisting. In particular, this phenomenon is more likely to occur as the frictional resistance between the photoconductor and the blade increases. The toner (for example, 10-point average particle diameter: 6.3 μm, minimum particle diameter: 3.2 μm) escapes from the slightly twisted portion, and is prevented by the pulverized toner having an average circularity of about 0.92. In some cases, toner particles having an average circularity of 0.98 to 0.99 (for example, 10-point average particle diameter: 5.6 μm, minimum particle diameter: 4.5 μm) produced by a polymerization method are almost continuous. It was confirmed that it escaped. Further, in the case of a photoreceptor (for example, Rv = 0.95 μm, Rp = 2.1 μm) used for copying and having a large surface roughness, even if the twisting or crushing of the blade can hardly be confirmed, it is not continuous. No cleaning failure has been confirmed.
[0054]
Another factor that causes the phenomenon of toner detachment is toner retention at the tip of the cleaning blade. This is because the toner is compressed by the strip-shaped blade due to the stagnation of the toner, so that the blade slightly floats.
[0055]
When the photoreceptor is used, the surface roughness gradually becomes rough and becomes large. However, when the maximum peak height Rp and the maximum valley depth Rv, which are the evaluation items of the surface roughness, are adjacent to each other, toner loss (toner cleaning failure) is caused. Be the largest. That is, when Ry (Rp + Rv) is larger than the minimum toner particle size D during use (Ry ≧ D), the toner easily exits. It is preferable that Rp <D and Rv <D, but it is particularly preferable that Ry <D, which has a high possibility. This relationship needs to be maintained while the photoreceptor is in use. Further, Rp, Rv, and Ry should be satisfied at least over the entire area in the circumferential direction of the photoconductor corresponding to the entire length of the cleaning blade.
FIG. 1 is an explanatory diagram of Rp, Rv, and Ry. FIG. 1 is an excerpt from JIS Handbook 2001 (No. 46), Machine Measurement Edition, published by the Japan Standards Association.
If the phenomenon that toner and carrier constantly come off under the cleaning blade continues, if the toner filming or other foreign matter adheres to the surface of the photoconductor, the maximum peak height Rp increases, and if the photoconductor is scratched, the maximum peak height Rp increases. Rp, the maximum valley depth Rv, and the sum Ry of the maximum ridge height Rp and the maximum valley depth Rv increase, and when Ry ≦ D, toner loss frequently occurs. For this reason, the photoconductor is more likely to cause a filming phenomenon, and the charging member is also contaminated, so that the image quality is deteriorated and the life of the photoconductor is shortened. In order to suppress the expansion of Rp, Pv, and Ry and prevent toner loss (cleaning failure), a cleaning system that completely blocks toner and carrier with a blade is important.
When the toner is removed from the cleaning blade, it causes not only the background contamination, but also a reduction in the life of the cleaning blade and a decrease in durability due to accelerated wear of the photoconductor. This leads to increased costs.
[0056]
The present invention has been made based on these findings. Therefore, the above object of the present invention is achieved by the following (1) to (13).
[0057]
(1) Charge is applied to an electrophotographic photosensitive member by a charging device, an electrostatic latent image is formed by optical writing, the electrostatic latent image is visualized with toner, and the toner is transferred to a transfer-receiving member. In an image forming apparatus using an indirect electrophotographic method of cleaning a body with a cleaning blade,
When the maximum valley depth of the surface roughness of the electrophotographic photosensitive member is Rv, the maximum ridge height is Rp, and the minimum particle size of the toner is D, the sum Ry of the maximum valley depth Rv and the maximum ridge height Rp and The minimum particle diameter D of the toner is Ry <D,
The cleaning blade is held so as to abut against the electrophotographic photosensitive member in the counter direction, and the cleaning blade has a knife-shaped or strip-shaped edge portion in contact with the electrophotographic photosensitive member, and has one surface in the longitudinal direction. An image forming apparatus comprising a rubber-like elastic body having a JIS-A hardness of 75 to 90 degrees reinforced with a metal plate.
[0058]
(2) The cleaning blade is subjected to a conductive treatment with a low-resistance substance over the entire length of one surface on the upstream side where the toner flows in the longitudinal direction, and is grounded. The image forming apparatus according to (1).
[0059]
(3) The image forming apparatus according to the above (1) or (2), wherein the minimum particle diameter D of the toner is 3 μm or more.
[0060]
(4) The image forming apparatus according to any one of (1) to (3), wherein the toner is a spherical toner.
[0061]
(5) The image forming apparatus according to (4), wherein the spherical toner has an average circularity of 0.940 to 0.995.
[0062]
(6) The electrophotographic photosensitive member is an organic photosensitive member in which a charge transport layer is formed at a position farthest from the conductive support, and the charge transport layer has a single-layer structure in which no filler is added, Or a filler non-dispersed charge transport layer t in which the charge transport layer has no clear interface between the two layers. ₁ And the filler-dispersed charge transport layer t ₂ When the thickness of the charge transport layer is t, 10 μm ≦ t ≦ 30 μm, and the filler non-dispersed charge transport layer t ₁ And the filler-dispersed charge transport layer t ₂ The relationship of the film thickness of t ₁ ≧ t ₂ And the filler-dispersed charge transport layer t ₂ Thickness of t ₂ ≦ 8 μm, the image forming apparatus according to any one of the above (1) to (5).
[0063]
(7) The image forming apparatus according to (6), wherein 10 to 40% by weight of alumina having an average particle size of 0.2 μm to 0.7 μm is dispersed in the filler-dispersed charge transport layer.
[0064]
(8) The surface friction coefficient of the electrophotographic photoreceptor is reduced by applying any one kind of lubricant of polytetrafluoroethylene or zinc stearate to the surface of the electrophotographic photoreceptor. The image forming apparatus according to any one of the above (1) to (7).
[0065]
(9) The image forming apparatus according to any one of (1) to (8), wherein the electrophotographic photosensitive member has a surface friction coefficient of 0.3 to 0.45 as measured by an Euler belt method. apparatus.
[0066]
(10) A tandem color system in which at least four systems of a charging device, a magenta, a developing device made of cyan, yellow, or black toner, an image exposing device, and a cleaning device are arranged around an electrophotographic photosensitive member. The image forming apparatus according to any one of the above (1) to (9).
[0067]
(11) An image forming method, wherein an image can be formed in an image forming apparatus using the cleaning blade, the toner, and the electrophotographic photoreceptor described in the above (1) to (10).
[0068]
The “minimum particle size D of the toner” in the present invention means the toner D having the smallest particle size obtained from the particle size distribution.
[0069]
The calculation of the toner average circularity described in the text is as follows.
Average circularity = Σ (perimeter of a circle having the same projected area as the particle image / perimeter of the projected particle image) / number of measured particles)
The number of particles to be measured is 1000 or more, and a particle having a particle diameter of 5 μm or more is selected for the calculation, and the toner image is projected to calculate the perimeter.
As a measuring device, there is FPIA-1000 type manufactured by Sysmex Corporation.
[0070]
Furthermore, the coefficient of friction was calculated using the Euler belt method (an equation calculated from Euler's formula).
A photoreceptor for measurement was fixed to a pedestal, and high-quality paper (manufactured by Ricoh Co., Ltd., type 6200 paper, using vertical mesh) cut to 30 mm in width and 290 mm in length was prepared as a belt, and the high-quality paper was exposed to light. Attach a 100 gr weight to one end of the belt, attach a digital force gauge for weight measurement to the other end, slowly pull the digital force gauge, The weight is read, and the (static) coefficient of friction μs is calculated from Equation 1.
μs = 2 / π × ln (F / W)
Where μs: coefficient of static friction, F: reading load
W: Weight of weight π: Pi
This measurement method (Euler-belt method) is also described in JP-A-9-166919.
[0071]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail.
The present invention relates to an image forming apparatus employing an indirect electrophotographic method of cleaning the surface of a photoreceptor with a cleaning blade, wherein the maximum valley depth Rv and the maximum ridge height Rp of the surface roughness of the electrophotographic photoreceptor and the toner Assuming that the minimum particle diameter is D, the sum Ry of the maximum valley depth Rv and the maximum peak height Rp and the minimum particle diameter D of the toner are Ry <D, and the cleaning blade counters the electrophotographic photosensitive member. The cleaning blade has a knife-shaped or strip-like edge reinforced with a metal plate over the entire surface in the longitudinal direction, and has a JIS-A hardness. It is characterized by being made of a rubbery elastic body of 75 to 90 degrees.
[0072]
A copying process using the indirect electrophotographic method according to the present invention will be described with reference to FIG.
In the copying process, the charging device 2, the image exposure device 3, the developing device 4, the transfer device 5, the separating device 6, and the cleaning device 7 (the cleaning device 7 is basically The fixing device 8 and the copy paper 9 are arranged respectively.
The photosensitive member 1 shown in FIG. 2 has a built-in vibration damping member 10 for suppressing vibration noise (high frequency sound) generated when an AC voltage is superimposed on a charging device. In that case, there is no need to specifically incorporate it.
[0073]
Further, in the present invention, as a means for reducing the friction coefficient of the surface layer of the photoreceptor and improving the abrasion resistance, cleaning property and transferability of the photoreceptor layer, the present invention describes that a lubricant is applied to the photoreceptor surface. ing. As the means, there is a method of applying to the photoreceptor using a lubricant applying device 200 (201 denotes a lubricant, 202 denotes a lubricant applying brush) as shown in FIG. .
[0074]
For color electrophotographic copiers and color laser beam printers, four photoconductors, which are advantageous in terms of copying speed, and four systems of yellow (Y), magenta (M), cyan (C), and black (Bk) There is a four-tandem tandem type copying system using a (color) developing device (FIG. 4), but the content of this copying device is basically the same as that of FIG. 2 only by repeating four copying cycles. .
[0075]
2 to 4 can also constitute an image forming apparatus as a process unit in which the photosensitive member and the cleaning member, the photosensitive member and the developing device and the cleaning member, and the photosensitive member and the developing device are integrally formed. It is.
FIG. 5 shows an example of a process unit incorporating the photoconductor, charging, transfer, and cleaning devices or members.
[0076]
The photoreceptor 1 has a configuration in which an undercoat layer (or an intermediate layer) is formed on a drum-shaped conductive support, and a photosensitive layer is formed thereon. The photosensitive layer includes a charge generation layer and a charge transport layer. Therefore, the thickness t of the charge transport layer is preferably set to 10 μm ≦ t ≦ 30 μm. The charge generation layer can be either inorganic or organic, as long as the hole / electron pairs (hole / electron pairs) generated by image exposure can move normally without delay to the charge transport layer and the conductive support side. Materials can also be used.
[0077]
In the present invention, the charge transporting layer is a single layer of a normal charge transporting layer in which no filler is dispersed (filler non-dispersed charge transporting layer) or a clear interface between the filler non-dispersed charge transporting layer and the filler dispersed charge transporting layer. It is preferable to be composed of two layers so as not to cause the following.
[0078]
That is, assuming that the thickness of the charge transport layer (the filler non-dispersed charge transport layer or the filler non-dispersed charge transport layer + the filler dispersed charge transport layer) is t, 10 μm ≦ t ≦ 30 μm. Further, the filler non-dispersed charge transport layer t ₁ Thickness and filler-dispersed charge transport layer t ₂ The relationship of the film thickness is t ₁ ≧ t ₂ And the filler-dispersed charge transport layer t ₂ Is t ₂ It is preferably set to ≦ 8 μm. (T ₂ = 0 μm, t ₁ = T)
[0079]
The filler of the filler-dispersed charge transport layer has a high hardness, ¹² An inorganic filler of Ω · cm or more is desirable, and any filler of alumina or titanium oxide can be preferably used.
Of these, alumina, which has a strong oxide film and little change in surface resistance and has good retention characteristics of the surface-treated water repellent, particularly α-alumina, is preferable, and the average particle size is 0.2 to 0.7 μm. It can be suitably used.
[0080]
The filler dispersion amount is desirably 10% by weight to 40% by weight based on the total weight of the filler-dispersed charge transport layer. The main reason for adding the filler is to improve the abrasion resistance and the resistance to the biting of the cleaning blade. Further, the frictional resistance between the cleaning blade and the photoconductor is reduced so that the cleaning blade is less likely to bite when the photoconductor rotates.
[0081]
Since the surface roughness of the photosensitive layer affects the toner cleaning failure, it is necessary to take care not to increase the surface roughness including the process conditions when a filler is added. The surface roughness is such that when the height of the peaks and the depths of the valleys on the surface of the photosensitive layer or the sum of the heights of the peaks and the valleys is larger than the toner particle diameter, the toner is liable to be constantly removed. Even if the particle size is smaller, the blade may easily come off due to the distortion of the blade. In fact, the contribution of the sum of the height of the mountain and the depth of the valley is large.
Therefore, when the maximum valley depth of the surface roughness of the electrophotographic photosensitive member is Rv, the maximum ridge height is Rp, and the minimum particle size of the toner is D, the sum Ry of the maximum valley depth Rv and the maximum ridge height Rp is: It is necessary that the minimum particle diameter D of the toner satisfies Ry <D.
[0082]
A lubricant can be applied to the surface layer of the photosensitive layer, if necessary. The application of the lubricant suppresses the cleaning blade from biting into the photoreceptor and relieves the distortion of the blade edge.This significantly reduces the abrasion of the photoconductive layer, reduces the adhesion of the toner to the photoreceptor, and transfers the image. The purpose is to increase the efficiency and improve the cleaning performance. Thus, even in the case of an organic photosensitive layer to which no filler is added (filler non-dispersed charge transport layer), the above-mentioned items can be satisfactorily improved.
[0083]
In forming an image, the photoconductor 1 is first charged by the charging device 2, and it is desirable that the photoconductor 1 be as low as possible in consideration of the influence of corona products, discharge breakdown, and the like.
It is necessary that the contrast potential at which good image forming properties are obtained is at least about 250 V. For this reason, it is desirable that the charged position be at least about -350 V to -400 V.
An upper limit of -1000 V is sufficient. Usually, if charging is performed at -800 V or less and the potential is maintained, no serious problem will occur in practical use.
[0084]
The charging method generates much less ozone than the corona charging method, and is a contact charging method that is environmentally advantageous or generates more corona products, but a non-contact charging method can be preferably used. The charging member used for charging includes a roller-shaped, brush-shaped, sheet-shaped member, a magnetic brush using magnetic powder, and the like, and any of them can be used in the present invention. In consideration of image quality, charging stability, durability and the like, a roller charging method using an elastic member is desirable.
[0085]
The roller type charging member is a SUS round bar of φ5 to φ15 (mm) on the core metal, and the elastic member for charging the photoreceptor is urethane rubber or hydrin rubber, carbon or metal fine powder, or an ion conductive agent. A control material is added, and if necessary, a water repellent such as a fluororesin is added so that the specific resistance is 10%. ⁴ -10 ¹² (Ω · cm) is used. The hardness is about 30 to 80 degrees in JIS-A hardness. The external dimensions are set to about φ10 to φ20 (mm) according to system conditions.
[0086]
In the case of contact charging, the hardness is desirably low in order to increase the nip and increase the stability of charging.In the case of non-contact charging, the hardness is not limited because it does not contact the photoreceptor, but hard fine powdery foreign matter When mixed, if the hardness is high, there is a high possibility that a pinhole will be formed in the photoreceptor. Therefore, it is desirable that the hardness is low including the cushioning action for the following reasons.
[0087]
When a hard conductive fine powder (aluminum powder, iron powder, etc.) is stuck in the photosensitive layer and pinholes are formed in the conductive support or the undercoat layer, discharge breakdown occurs and the conductive layer becomes completely conductive. In such a situation, since a current flows from the charging roller, when a charging member having a low specific resistance is used, a black band is generated in a portion having a pinhole in the length direction of the charging member. On the other hand, if it is too high, the charging characteristics will deteriorate. ⁵ -10 ¹⁰ (Ω · cm) is used.
[0088]
In the case of using the brush charging method, one brush is made of 10 to 100 filaments / bundle of 3 to 10 denier conductive fibers (for example, fibers obtained by adding carbon, an ionic conductive agent and the like to polyester fibers), and 80 to 600 filaments. A conductive brush in which the hairs are planted at a density of 1 / mm on the support and the bristle feet are cut between 1 and 10 mm can be suitably used.
[0089]
On the other hand, when the magnetic brush charging method is used, Zn-Cu ferrite particles having an average particle diameter of 25 μm and Zn-Cu ferrite particles having an average particle diameter of 10 μm are mixed at a weight ratio of 1: 0.05. By mixing, ferrite particles having an average particle diameter of 25 μm having a peak at each average particle diameter position were coated with a medium-resistance resin layer using magnetic particles, and the coated magnetic particles were coated on a sleeve to a thickness of 1 mm. And use it as a magnetic brush.
[0090]
The charging member is applied with a DC voltage of -1100 V to -1500 V alone or a DC voltage obtained by superimposing an AC voltage of 1000 V to 2000 V / 500 Hz to 4500 Hz on a DC voltage of -500 V to -1500 V. Usually, a sine wave is generally used as the waveform of the AC voltage, but a triangular wave (or sawtooth wave) may be used.
[0091]
The electric field intensity applied to the photoconductor is (-) 1.3 × 10 ⁵ ~ 4.5 × 10 ⁵ (V / cm). This electric field strength is equivalent to charging the photosensitive member of 10 to 30 μm to (−) 350 to 800 (V). If the electric field intensity applied to the photoreceptor during image formation is large, the probability of reaching a discharge breakdown phenomenon when a pinhole occurs in the photosensitive layer increases, and if the electric field intensity is low, the image quality may be poor. Therefore, it is important to set an appropriate electric field strength for the photosensitive layer.
[0092]
After the charging, the photoreceptor 1 receives one or a plurality of LD (Laser Diode) elements or an LED (Digital Signal) from a document image read by a CCD (Charge Coupled Device) or a digital signal transmitted from a personal computer or the like. (Laser Emitting Diode) A single wavelength optical image narrowed down to a dot diameter of about 60 to 20 μm is radiated by an image exposure device 3 including an array, a convex lens, a polygon mirror, a cylindrical lens, and the like, and an electrostatic charge corresponding to an input signal is emitted. A latent image is formed. As the LD element or the LED array, an element having an emission wavelength corresponding to the highest sensitivity region of the photoconductor is selected. Since the spot diameter can be narrowed as the emission wavelength becomes shorter, an LD element having an oscillation wavelength on the short wavelength side of about 400 to 450 nm is advantageous in obtaining high resolution such as 1200 or 2400 dpi. It can be used by mounting it on a forming device.
[0093]
The contrast potential required for image formation is usually set to be 250 V to 600 V.
Here, the contrast potential refers to the difference [Δ (Vl−Vb)] between the bright portion potential Vl and the developing bias potential Vb. The developing bias potential Vb is set to be higher by about 50 to 150 V than the charged potential Vd in consideration of the background contamination margin due to the repeated potential fluctuation.
[0094]
To visualize the electrostatic latent image formed on the photoconductor 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. In the present invention, a two-component developer is mainly used.
[0095]
The carrier of the two-component developer includes, for example, polyfluorocarbon to improve the chargeability, charge stability, durability and the like of powder having magnetic properties (magnetic powder) such as iron powder, ferrite powder and nickel powder. A resin coated with a resin such as polyvinyl chloride or polyvinylidene chloride is used. The particle size of the carrier is about 30 to 60 μm.
The particle size of the carrier affects the resolution, and a smaller particle size tends to improve the resolution. However, if the particle size is too small, it tends to adhere to the photoreceptor, resulting in poor transfer of the toner image (transfer loss), When conveyed to the cleaning section, the blade is pressed against the photoconductor by the blade, so that the photoconductor surface is damaged, which also contributes to shortening the durability of the photoconductor.
[0096]
On the other hand, the toner includes a toner manufactured by the above-described pulverization method, a toner that has been subjected to spherical processing by shaving an angular area of the toner, or a toner manufactured by a polymerization method (emulsion polymerization method, suspension polymerization method, etc.). A toner having a minimum particle size of preferably 3 μm, a toner having D ≧ 3 μm and preferably having a weight average particle size of 4 to 8 μm, and 2 to 10 (wt%) ) Are mixed.
The particle size of the toner also affects the resolution similarly to the carrier. However, if the particle size is too small, there is a concern that the toner may harm health when scattered (environmental destruction = pollution).
[0097]
When the development is completed, a voltage (or an electric field) having a polarity opposite to the charge held by the toner is applied by using the transfer device 5, and the toner image is transferred to the copy paper 9. FIG. 2 illustrates a belt-shaped transfer device 5 (the transfer belt basically includes a support base, an elastic layer, and a coating layer). In addition, a roller shape (FIG. 3), a brush shape, A corona discharge type transfer device can be used.
After the transfer is completed, the copy sheet is separated from the photoreceptor 1 by the separation device 6 to which an AC voltage or a DC voltage on which the AC voltage is superimposed is applied and sent to the fixing device 8 to be a hard copy. The separation device 6 is generally a corona discharge device that applies an AC voltage obtained by superimposing an AC voltage or a DC voltage on a metal wire or a saw-tooth electrode. Since the electric field intensity applied to the photoreceptor via the copy paper may be an amount such that the copy paper is separated from the photoreceptor, the amount of corona generated is small, and is not large enough to damage the photoreceptor. When the diameter of the photosensitive member is 30 mm or less, the separating device may be omitted depending on the stiffness of the paper.
[0098]
On the other hand, the residual toner on the photoreceptor after separation of the copy paper is constituted by a cleaning blade 7-1 made of a material such as polyurethane rubber, silicone rubber, neoprene rubber, or fluoro rubber (further, polyethylene, nylon, carbon fiber, etc. Is cleaned by the cleaning device 7 (combined with a cleaning brush made of the above-mentioned fibers), and a series of copying processes is completed.
[0099]
Here, the photoconductor will be described in more detail.
As described above, the photoreceptor is, for example, a photoreceptor formed on a drum-shaped aluminum conductive support in the order of an undercoat layer, a charge generation layer, and a charge transport layer, and the charge transport layer is at least an organic photosensitive layer. Be composed.
FIG. 6 shows a schematic diagram of the photoconductor. The charge transport layer can be used alone with the organic photosensitive layer. In order to improve the durability of the photoreceptor and the maintenance performance of image quality, as shown in FIG. 7, a cleaning blade and a filler-dispersed charge transporting layer in which a high-hardness filler is dispersed on the surface of the photosensitive layer directly contacted with the developer are used. It is preferably formed on an organic photosensitive layer.
[0100]
The charge transport layer composed of the filler non-dispersed charge transport layer and the filler dispersed transport layer is a layer in which a low molecular charge transport material is dispersed with an appropriate amount of a binder resin, an antioxidant, a dispersant, and the like, or a polymer charge. The film thickness and the layer structure can be set according to the required quality of the photoreceptor.
[0101]
The first purpose of adding a filler (in the present invention, an inorganic filler composed of alumina (α type) is particularly preferably used) is to increase the hardness of the surface layer of the photoreceptor by adding an appropriate amount of the filler. Pencil hardness Hp is HB ≦ Hp <2H) By increasing the abrasion resistance, the life of the photoconductor is prolonged and the image quality is stabilized. However, a significant increase in hardness may cause image deterioration such as image deletion in order to reduce wear of the photosensitive layer.
[0102]
Here, the pencil hardness refers to a pencil scratch tester (surface property measuring device HEIDON-14 type manufactured by Shinto Kagaku Co., Ltd.) manufactured based on JIS K 5401 and a JIS standard pencil (Mitsubishi Pencil "Uni"). When used and measured with a weight of 100 g (weight), it is defined as the pencil hardness in the present invention.
[0103]
Means for measuring hardness include scratch hardness, Vickers hardness, Knoop hardness, and the like, in addition to pencil hardness. For a filler-dispersed charge transport layer in a dispersion system, abrasion such that the photosensitive layer is rubbed by a blade ( (Abrasive wear), it is a desirable method to determine by a pencil hardness measurement method. If the amount of filler added is large or the dispersed particle size is large, the pencil hardness increases and the abrasion resistance improves, but the surface roughness increases, the image quality decreases, and foreign substances such as corona products adhere. Too high a hardness is not desirable because it tends to be easy to do.
[0104]
The second purpose is to disperse a small particle size filler on the surface of the photosensitive layer to set it to a suitable hardness, to suppress a large increase in the coefficient of friction, and to prevent the cleaning blade edge from penetrating into the layer. Therefore, distortion and deformation of the blade edge are reduced as much as possible, and toner that has not been blocked by the cleaning blade (particularly, spherical toner produced by a polymerization method having a large circularity) is prevented from coming off the blade as much as possible. .
[0105]
Here, if the surface of the photosensitive layer is a resin layer to which no filler is added, the coefficient of friction (or free surface energy) is large due to the action of corona products, paper powder, toner components, atmospheric moisture, and the like. During cleaning, the blade edge bites into the photoconductor, and is dragged in the rotation direction of the photoconductor, causing deformation and local distortion, creating a gap between the photoconductor and the toner, and causing factors to cause toner loss. In addition, the crushed blade presses the toner against the photoreceptor, causing further stagnation of the toner, which further increases the toner loss. However, when the surface energy (or coefficient of friction) of the surface layer of the photoreceptor is reduced by a lubricant or the like, toner removal is improved, but reduction of the surface energy alone is not sufficient.
In order to minimize such deformation and distortion, a filler is dispersed in the photosensitive layer to prevent an extreme increase in the coefficient of friction and to suppress biting.
[0106]
However, since toner removal is not sufficient only by using the above-described photoconductor containing a filler, in order to improve the cleaning performance of spherical toner to a level close to 100%, even when the photoconductor is rotating, The object can be achieved by using a specific cleaning blade that maintains line contact without crushing or distortion of the blade edge and does not cause a state in which toner is not crushed by the blade. Further, if necessary, a lubricant is applied to the surface of the photoreceptor to reduce the coefficient of friction of the surface of the photoreceptor, thereby ensuring long-term stable cleaning performance and maintaining the durability of the cleaning blade.
[0107]
It is extremely useful to change the low-molecular-weight charge-transporting material, which is a constituent material of the charge-transporting layer, to a high-molecular-weight charge-transporting material in order to improve abrasion resistance.
[0108]
The thickness of the photosensitive layer is desirably a film thickness that can secure a charging potential for obtaining a sufficient contrast image and a contrast potential. If the contrast potential (difference between the developing bias potential and the image portion potential) is 100 V, it is possible to form a character image at a relatively good level, but in the case of a photographic image, the density is insufficient. Not a target. In order to obtain good image forming properties, it is desirable to secure a contrast potential of at least 250 V or more.
[0109]
It is preferable that the total film thickness of the photosensitive layer is set to 10 μm or more as a film thickness capable of ensuring a contrast potential. When the film thickness is reduced to 10 μm or less, a sufficient charging potential cannot be secured, and a sufficient contrast potential is hardly obtained. Further, unevenness in the thickness of the photosensitive layer is easily reflected on the image as it is, resulting in non-uniform image quality. On the other hand, if the thickness is too large, the dot pattern spreads in the layer, causing a reduction in sharpness and resolution, making it difficult to achieve a high-quality image.
[0110]
The thickness t of the photosensitive layer preferably satisfies 10 μm ≦ t ≦ 30 μm in order to form an image with higher contrast.
[0111]
(Conductive support)
Materials that can be used as the conductive support of the photoreceptor include metals such as stainless steel, copper, and brass that satisfy various electrical, mechanical, and chemical properties, as well as compressed paper, resin, and glass, gold and aluminum, Examples include a conductive layer on which platinum or chromium is deposited or sputtered, and a conductive layer on which fine particles such as carbon or tin are dispersed. In view of the fact that thin cutting is easy to perform, light, advantageous for reproduction, easy to form a blocking layer, easy to obtain, and the like, aluminum, particularly an aluminum alloy such as JIS3003 is preferable.
[0112]
The technologies for processing the surface of aluminum include cutting, honing, and blasting.The drum-shaped aluminum tube is cut to the required length, cut to the target outer diameter, and then super-finished. , Mirror finish, etc., to make the surface roughness 10 points average roughness Rz _JIS And then sufficiently washed until the washing solution is completely removed, and used as a conductive support for an electrophotographic photosensitive member. The roughness of the support is covered to some extent by the undercoat layer. However, if the surface roughness is as large as 10 μm or more, the undercoat layer cannot cover the unevenness. Charge injection occurs, and abnormal images such as streak patterns, white spots, and black spots on the image are likely to appear on the entire copy sheet.
[0113]
Aluminum is an oxide film (Al ₂ O ₃ ) Is easy to form, but the electrical resistance for maintaining the electrophotographic characteristics is 10 ⁶ There is no particular problem as long as the value is on the order of Ω · cm or less.
The conductive support has a drum shape and an outer diameter of about φ30 mm to φ80 mm is generally used.However, in the case of a large-sized image forming apparatus, in order to cope with durability and mass copying, a diameter of φ80 mm or more is used. An outer diameter is used.
[0114]
The thickness of aluminum is about 0.6 mm to 3 mm for a photoreceptor having an outer diameter of φ30 to φ80 (mm). Therefore, if the material does not deform at such a temperature, the cost is reduced, and if the vibration damping member is incorporated as a suppression means when charging is performed using a DC voltage superimposed on the AC voltage, the conductive property is reduced. The thickness of the support is preferably thin. By reducing the wall thickness, vibration generated by charging can be quickly transmitted to the vibration damping member, so that the vibration damping function can be effectively exhibited.
[0115]
(Undercoat layer)
An undercoat layer is provided between the conductive support and the photosensitive layer, if necessary. The form of the undercoat layer may vary depending on the wavelength range used for the light source. For example, when used for a light source such as an LD element or an LED array having an oscillation wavelength in a long wavelength region of 650 to 780 nm, moire occurs due to the reflection of light from aluminum, so that the undercoat layer or a similar layer is used. The formation of an anti-reflection thin film is indispensable, but 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 a lower layer as described in a specific example of the present invention is used. The pulling layer is not necessarily required, and may be a thin film having a thickness of 1 μm or less, such as alumina, or a semiconductor film that prevents hole injection. The following description is for the case where a light source having an oscillation wavelength in a long wavelength region (infrared region) is used.
[0116]
The reason for forming the undercoat layer is to prevent charge injection from the support side, stabilize charging characteristics, improve adhesion, prevent moiré, improve coatability of the upper layer, reduce residual potential, etc. With the goal. Therefore, a method may be adopted in which a semiconductor film is formed to prevent injection of holes (holes) and allow electrons (electrons) to pass therethrough, and further form an intermediate layer or an undercoat layer thereon. In general, the undercoat layer is formed of a thin film containing a resin as a main component and having a high resistance so that potential decay hardly occurs within a unit time.
[0117]
Considering that the undercoat layer is to be coated with a photosensitive layer using a solvent, it is preferable that the undercoat layer be a resin having high solubility resistance to general organic solvents. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, and epoxy resin. And a curable resin forming a three-dimensional network structure. Further, fine powders of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be dispersed and contained. These undercoat layers can be formed using a suitable solvent and a coating method.
[0118]
Further, as the undercoat layer of the present invention, a metal oxide layer formed by using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like by a sol-gel method or the like is also useful.
In addition, as the undercoat layer of the present invention, Al ₂ O ₃ , An organic substance such as polyparaxylylene (Parylene = trade name of Union Carbide), SnO ₂ , TiO ₂ , CeO ₂ Inorganic substances such as are provided by a vacuum thin film manufacturing method. ¹⁰ -10 ^Thirteen A thin film having an electrical resistance on the order of (Ω · cm) can be used favorably.
[0119]
The thickness of the undercoat layer is suitably from 0.1 to 20 μm, and preferably from 1 to 10 μm.
[0120]
(Charge generation layer)
The charge generation layer is a layer containing a charge generation substance as a main component, and a binder resin is used as necessary. As the charge generation substance, there are an inorganic material and an organic material.
[0121]
Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and amorphous silicon. In amorphous silicon, a material obtained by terminating a dangling bond with a hydrogen atom or a halogen atom, or a material obtained by doping a boron atom, a phosphorus atom, or the like is preferably used.
[0122]
On the other hand, as the organic material, a known material can be used. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulhenium salt pigment, methine squaric acid pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzo Azo pigment having a thiophene skeleton, azo pigment having a fluorenone skeleton, azo pigment having an oxadiazol skeleton, azo pigment having a bisstilbene skeleton, azo pigment having a distyryl oxadiazol skeleton, distyryl carbazole skeleton Having an azo pigment, a perylene pigment, an anthraquinone or polycyclic quinone pigment, a quinone imine pigment, a diphenylmethane and triphenylmethane pigment, a benzoquinone and a naphthoquinone pigment, a cyanine and an azomethine pigment, Njigoido pigments, bisbenzimidazo - such as Le based pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.
[0123]
Binder resins used as needed in the charge generation layer include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, and polyvinyl formal. , Polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, polyacrylamide, and the like. These binder resins can be used alone or as a mixture of two or more. In addition, a low molecular charge transport material may be added as needed.
[0124]
Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trione An electron accepting substance such as nitrodibenzothiophene-5,5-dioxide is exemplified. These electron transport materials can be used alone or as a mixture of two or more.
[0125]
Examples of the hole transporting substance include the following electron donating substances, and are preferably used.
For example, oxazole derivatives, oxadiazol derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene , Styryl pyrazolines, 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.
[0126]
The charge generation layer contains a charge generation substance, a solvent, and a binder resin as main components, and may include any additives such as a sensitizer, a dispersant, a surfactant, and a silicone oil. good.
[0127]
As a method for forming the charge generation layer, a vacuum thin film preparation method and a casting method from a solution dispersion system are largely mentioned. For the former method, a vacuum evaporation method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-mentioned inorganic material and organic material can be favorably formed. . Further, in order to provide a charge generation layer by a casting method, if necessary, a ball mill using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a binder resin if necessary for the inorganic or organic charge generation material described above, It can be formed by dispersing with an attritor, a sand mill, or the like, diluting the dispersion liquid appropriately, and applying. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like.
[0128]
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, and preferably 0.05 to 2 μm. Usually, it is applied to a thickness of 0.1 to 0.3 μm.
If the film thickness is too small, sensitivity is poor, but if it is too thick, light attenuation and residual potential increase due to space charge, resulting in image quality deterioration such as image density reduction and resolution reduction.
[0129]
(Charge transport layer)
The charge transport layer is formed to secure a surface potential required for image formation. The charge transport layer can of course be used alone with an organic photosensitive layer. However, in order to maintain the durability of the photoreceptor and maintain the image quality, the surface of the organic photosensitive layer (non-filled charge transport layer) should have a higher hardness. To form a filler-dispersed charge transport layer to which an appropriate amount of ultrafine particles of an inorganic filler is added.
In the present invention, as shown in FIG. 7, the charge transport layer is composed of a non-filler-dispersed charge transport layer and a filler-dispersed charge transport layer, and has such a structure that no clear interface exists between both charge transport layers. Here, the absence of a clear interface means that the filler non-dispersed charge transporting layer and the filler dispersed charge transporting layer are not formed as one layer, but the layers are intermingled with each other and no barrier is formed. I do.
By avoiding the formation of a clear interface, most of the holes and electron pairs generated by image exposure that move toward the surface layer are not captured near the interface. In addition, it is possible to cancel the charge transferred to the surface layer and applied by charging without loss of time.
[0130]
That is, since the optical attenuation characteristic hardly deteriorates, high-definition image quality can be reproduced.
However, since the filler is dispersed, a slight loss due to the amount of dispersion of the filler, the particle size, etc., for example, light diffusion, variation in charge distribution occurs, but when added in a suitable range, it can be ignored. And there is no practical problem.
[0131]
When an interface is formed between the two charge transport layers, the movement of holes is restricted, so that the light attenuation characteristic is degraded and the residual potential is increased, so that the contrast potential is reduced and the afterimage is easily caused.
[0132]
The coating means for preventing the formation of 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 is provided on one of the two spray guns. Inject the liquid and the filler-dispersed charge transport layer liquid in the other, apply the filler non-dispersed charge transport layer on the charge generation layer first, wait for a touch drying time (several minutes), and then continue the filler dispersion. What is necessary is just to apply a charge transport layer. When the charge transport layer is as thick as 25 μm or 30 μm, and when the filler non-dispersed charge transport layer is as thick as 20 μm, first, the filler non-dispersed charge transport layer is formed, touch dried, and further dried by heating at 120 to 130 ° C. Thereafter, the filler-dispersed charge transport layer is formed in a relatively short time, and the entire photoconductor is heated and dried at a temperature of 130 to 160 ° C. for about 10 to 60 minutes, whereby the photoconductor can be manufactured without any problem.
[0133]
The charge transporting layer (filler non-dispersed charge transporting layer + filler dispersed charge transporting layer) is formed by dissolving or dispersing a mixture or copolymer containing a charge transporting component and a binder component as main components in a suitable solvent. It can be formed by coating to a required thickness and drying.
[0134]
The thickness of the charge transport layer is set to 10 to 30 μm. However, the smaller the variation (the difference between the maximum thickness and the minimum thickness) of the entire photosensitive layer is, the more easily the influence of coating unevenness occurs. Desirably, the distance is set within a range of ± 1 μm for 10 μm and ± 2 μm for 30 μm. Among these, the tightening ratio (occupancy) of the thickness of the filler-dispersed charge transport layer is preferably 6.7% to 80%, and the maximum thickness is 8 μm.
[0135]
The smaller the thickness of the photosensitive layer, the larger the capacitance, so that the electric field strength increases. However, it is difficult to secure a high charge level. If the charge of the toner is small, the developing ability can be increased even with a photoreceptor with a small film thickness, but at present, the toner with a small particle diameter generally used in the market must be subjected to voltage development. Therefore, a certain or more surface potential is required.
[0136]
When the thickness of the photosensitive layer is reduced, the distortion of the charge transfer is reduced, so that a high-quality image can be reproduced. On the other hand, the larger the thickness, the smaller the capacitance, so that a high charge level can be secured. However, when the charge moves, the charge tends to be distorted at the time of light input, and the resolution tends to decrease. Is the limit.
[0137]
When the thickness of the photosensitive layer is set to about 10 μm, the charged portion is charged only at about −450 V at most. However, if the residual potential is suppressed to about -50 V to -100 V and the developing bias potential is set to -350 V, the contrast potential can be secured at about 250 V to 300 V, so that there is practically no problem in image formation. It becomes.
[0138]
The charge transport layer is formed on the charge generation layer in the order of the filler non-dispersed charge transport layer and the filler dispersed charge transport layer. This is because, when the filler-dispersed charge transport layer is in direct contact with the charge generation layer, abnormal movement of charges occurs between the filler-dispersed charge transport layer and the charge generation layer, so that a speckle pattern appears on the image. Therefore, it is preferable that the charge transporting layer does not disperse the filler in the region in contact with the charge generating layer, and it is desirable that the film thickness be at least 2 μm or more.
[0139]
For coating film formation, a dip coating method, a spray coating method, or the like can be used.
[0140]
The filler added to the filler-dispersed charge transport layer is spherical and has high hardness, has optical transparency, and has an electric resistance of 10%. ¹⁰ It is desirable that it be Ω · cm or more. Preferably 10 ¹² (Ωcm) -10 ^Thirteen (Ω · cm). If the specific resistance is low, it is difficult to hold the charge, and if the specific resistance is too high, the resolution is lowered.If the specific resistance is too high, the residual potential is increased, the image portion potential is increased, the contrast potential is reduced, and a sufficient image density cannot be obtained. , Resulting in an image with many irregularities.
[0141]
The filler in the filler-dispersed charge transport layer is preferably uniformly dispersed in the charge transport layer, or a layer configuration in which the concentration gradient is increased toward the surface layer, but from the viewpoint of maintaining durability, Uniform dispersion is more desirable.
The amount of the filler dispersed in the charge transport layer depends on the required durability (depending on abrasion, chemical and physical deterioration), and image quality (depending on the aging characteristics such as charge level, sensitivity and residual potential). Affected), but 10% by weight to 40% by weight of the total weight of the filler-dispersed charge transport layer is desirable. When the content is less than 10% by weight, the abrasion increases rapidly. When the content is more than 40% by weight, the residual potential increases, the surface roughness of the photosensitive layer deteriorates, and toner filming easily occurs due to the surface roughness. Is suppressed, and image deletion is likely to occur.
[0142]
The thickness of the filler-dispersed charge transporting layer depends on the particle size and amount of the filler dispersed in the photosensitive layer, and needs to be changed depending on the durability required for the photoreceptor and image quality characteristics. From the viewpoint of durability, it is desirable that the filler-dispersed charge transporting layer be thick. And the image quality (decrease in contrast) is affected.
On the other hand, when the film thickness is reduced, the resolution tends to be improved, but the durability is lowered. It is desirable to set the film thickness to at least 2 μm or more.
[0143]
The materials used for the charge transport layer are as follows.
Oxazole derivatives, oxadiazole derivatives, imidal derivatives, triphenylamine derivatives, α-phenylstilbene derivatives, toniphenylmethane derivatives, anthracene derivatives, and the like can be used as the low-molecular-weight charge transporting material constituting the charge transporting layer.
[0144]
On the other hand, as the polymer charge transporting substance, the following known polymer charge transporting materials can be used. For example,
1) Polymers having a carbazole ring in the main chain and / or side chain include, for example, poly-N-vinyl carbazole, JP-A-50-82056, JP-A-54-9632, There are the compounds described in JP-A-54-11737 and JP-A-4-183719.
[0145]
2) Polymers having a hydrazone structure in the main chain and / or side chain include, for example, compounds described in JP-A-57-78402 and JP-A-3-50555.
[0146]
3) Examples of the polysilylene polymer include compounds described in JP-A-63-285552, JP-A-5-19497, and JP-A-5-70595.
[0147]
4) Polymers having a tertiary amine structure in the main chain and / or side chain include, for example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-13061, JP-A-1-19049, JP-A-1-1728, JP-A-1-105260, JP-A-2-167335, JP-A-5-66598, and compound described in JP-A-5-40350 Etc.
[0148]
5) Other polymers include, for example, formaldehyde polycondensates of nitropyrene and compounds described in JP-A-51-73888 and JP-A-56-150749.
[0149]
The polymer having an electron donating group used in the present invention is not only the above-mentioned polymer, but also a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, and, for example, It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-3-109406.
[0150]
As the polymer charge transporting material in the present invention, a polycarbonate having a triarylamine structure in the main chain and / or side chain is effectively used.
On the other hand, examples of the high molecular compound that can be used as the binder component include polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester resin, polyvinyl chloride, and chloride. Vinyl / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate resin (bisphenol A type, bisphenol C type, bisphenol Z type or a copolymer thereof), cellulose acetate resin, ethyl cellulose resin, polyvinyl Thermoplastic or heat of butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. Including but of resin, but is not limited thereto. These polymer compounds can be used singly or as a mixture of two or more kinds, or copolymerized with a charge transport material.
[0151]
Examples of dispersion solvents that can be used when preparing the charge transport layer coating liquid include, for example, methyl ethyl ketone, acetone, methyl isobutyl ketone, ketones such as cyclohexanone, dioxane, tetrahydrofuran, ethers such as ethyl cellosolve, toluene, xylene and the like. Examples thereof include aromatics, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate. However, it is desirable to avoid using a halogen-based solvent in consideration of environmental destruction.
[0152]
Next, the filler dispersed in the charge transport layer will be described.
The filler used in the present invention is an oxide insulator, and when dispersed in a binder resin, traps are easily formed at the interface between the particles and the binder resin. Therefore, when the photoreceptor is used repeatedly, the residual potential accumulates and the potential of the image portion is increased, so that the image density and the resolution are easily reduced. Therefore, an additive can be added to improve the dispersibility, uniformize the photosensitive layer, inhibit the formation of traps, or reduce the trap density.
[0153]
Means for applying a charge to the photoreceptor when forming an image is performed by a charging device that is in contact with or close to the photoreceptor. It attaches to the surface layer or penetrates into the photosensitive layer, lowering the electrical resistance and causing deterioration in image quality such as resolution. In order to solve this, a small amount of an antioxidant and a plasticizer can be added. However, these additives are not always necessary, and they may be omitted when the charge transport layer is thin, when the amount of filler added is small, or depending on the image system.
In the charge transporting layer to which the filler is added, a coating liquid in which a suitable amount of the filler is dispersed in a binder resin is applied to a target film thickness by using a coating method such as a spray method or a dipping method.
[0154]
Filler is 10 ¹⁰ -10 ^Thirteen (Ω · cm), desirably having water repellency and maintaining its function. Especially 10 ¹² -10 ^Thirteen (Ω · cm).
The filler material includes an organic filler material and an inorganic filler material. Examples of the organic filler material include a fluororesin powder such as polytetrafluoroethylene, a silicone resin powder, and an amorphous carbon powder. Inorganic filler materials include metal powders such as copper, tin, aluminum and indium, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide and antimony. Metal oxides such as tin oxide doped with tin, indium oxide doped with tin, 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 wear resistance.
In particular, titanium oxide or alumina can be desirably used in the present invention, but alumina (particularly α-type) is more preferable. These fillers can be used alone or as a mixture.
[0155]
The filler material can be dispersed by using a suitable disperser together with a charge transporting substance, a binder resin, a solvent and the like.
[0156]
When the surface roughness of the photosensitive layer is increased by the addition of the filler, the edges of the character become jagged, and the cleaning properties of the residue such as toner and paper powder are deteriorated, resulting in a problem of poor cleaning. Contaminants such as corona products remain in areas where the blades do not contact, causing image bleeding, toner filming and even chipping of the edges of the cleaning blade, making the photosensitive layer more susceptible to damage. Therefore, it is necessary to select a filler having a particle size with good dispersibility so that the target abrasion resistance can be achieved and good image quality can be obtained. The primary particle size of the filler dispersed in the photosensitive layer is selected from the light transmittance, abrasion resistance, surface roughness and the like of the charge transport layer.
[0157]
FIG. 8 shows a pulverized toner having a weight average particle diameter (peak value of particle diameter distribution) of 6.3 μm (minimum particle diameter of toner: 3.4 μm) and an average circularity of 0.932; This is an example (measured using Surfcom 1400D, Tokyo Seimitsu Co.) of surface roughness before image formation in combination with a φ30 mm photoreceptor having a 5 μm filler-dispersed charge transport layer containing 25% by weight of alumina. FIG. 9 shows a measurement example of surface roughness when 15,000 sheets of paper were run.
In FIG. 8, Rp is 0.3 μm, Rv is 0.3 μm, and Ry is 0.6 μm.
In FIG. 9, Rp is 0.65 μm, Rv is 0.27 μm, and Ry is 0.92 μm.
[0158]
Although not shown, the surface roughness tends to be increased by 30,000-sheet running, but there is still enough room to increase to the toner diameter. In other words, it is recognized that even if the toner having a small particle diameter is present, the toner is hardly removed or the magnetic powder is hardly removed, so that the surface roughness of the photosensitive member is maintained at a relatively low level.
[0159]
As the particle size of the filler added to the filler-dispersed charge transport layer increases, the surface roughness physically increases. For example, at 0.5 μm, Ry before image formation becomes as large as 0.94 μm, but after running 15,000 sheets, it becomes large with roughness of the photosensitive layer surface and becomes 1.2 μm.
When alumina having a particle diameter of 1 μm is used for the filler, the surface roughness Ry (Rp + Rv) of the photoreceptor before image formation was 1.76 μm, although it depends on the production method, but was 15,000. Ry is about 3 μm after the sheet is printed, and when a toner having a small particle size of about 3 μm is used, there is a high risk that cleaning failure will occur.
[0160]
Usually, most toner particles used for development have a diameter of about 5 μm to 8 μm. However, since the average particle diameter is used, toner having a smaller particle diameter than the indicated value is actually used (about 2 to 5 μm in the above example). ) Is mixed. Also, when the edge of the cleaning blade is distorted, even if Rp + Rv = Ry is smaller than the toner diameter, there is a possibility that toner may be removed. Therefore, the blade edge should not be distorted. is necessary.
[0161]
When the toner loss occurs locally, filming occurs in a band shape from the portion where the toner loss occurs as a generation source, and the influence gradually spreads to other regions, and the filming tends to spread throughout. From this, it is considered that there is a high possibility that a problem will occur in practicality when a 1 μm filler is used.
However, as long as the toner is completely blocked immediately before the blade and the initial state is maintained, there is no possibility that a filler having a diameter of 1 μm cannot be used. However, if the blade is slightly twisted or distorted, there is a possibility that the toner having a small particle diameter may come off. Therefore, it is desirable that the filler having a particle diameter of 0.7 μm or less, and further, a filler having a particle diameter of 0.5 μm to 0.3 μm is used. It is good to use a filler.
If the toner is constantly removed, the filming phenomenon is likely to occur, so that Rp increases. On the other hand, when a hard foreign substance such as a carrier comes off, scratches occur and Rv increases.
[0162]
When the lower limit of the filler particle size is 0.2 μm, it is sufficient. When the particle size is smaller than 0.2 μm, the surface roughness can be kept low, but the wear resistance cannot be maintained.
Note that the initial Ry of the non-dispersed charge transporting layer of the filler is about 0.12 μm even after running 100,000 sheets of paper, and is not at a level that directly affects toner loss.
[0163]
As a means for eliminating the roughness of the photosensitive layer surface and smoothing it, for example, adding a leveling agent to the charge transport layer according to the invention is an effective means.
As the leveling agent, a known material can be used. However, a silicone oil-based leveling agent, which can impart a high level of smoothness in a small amount and has a small effect on electrostatic characteristics, is particularly preferable. Examples of silicone oils include dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen polysiloxane, cyclic dimethyl polysiloxane, alkyl-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, and amino-modified silicone oil. Examples include silicone oil, mercapto-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, higher fatty acid-modified silicone oil, and higher fatty acid-containing silicone oil.
[0164]
In addition, it is possible to reduce unevenness depending on conditions at the time of coating and the like. For example, in dip coating, after lifting the photoreceptor, when the coating surface is still wet, unevenness is reduced by covering it with a hood so that the surface is not disturbed by wind current etc. You. Also, if the solvent near the surface of the coating film evaporates rapidly, only the surface is hardened and the inside of the coating film becomes fluid, and the coating film inside this film may sag and form irregularities. In a wet state, a vapor layer of a solvent is formed around the photoreceptor, and the solvent is gently volatilized, whereby leveling progresses, and unevenness is reduced and smoothed.
[0165]
Also, in spray coating, when forming a coating film by air spray, by controlling the air pressure and the air flow rate to an appropriate amount, the surface of the coating film in a fluid state is suppressed and irregularities are suppressed. It is necessary to control. Here, if the air pressure and air flow rate are too large, the surface of the coating film will be disturbed by the flow of air, while if too small, the droplets of the coating liquid will not be uniform or atomization will be insufficient. As a result, the uniformity of the coating film is reduced. After the charge transport layer is formed, the solvent is volatilized while being rotated. If the rotation speed is too high, centrifugal force is applied to the coating film which still contains the solvent and has fluidity, so that unevenness is emphasized. On the other hand, if the rotation speed is too low, the effect of sagging due to gravity is greater than the leveling due to rotation, which may cause unevenness. Therefore, it is necessary to set the rotation speed of the photoconductor in a wet state of the coating film to an appropriate value.
[0166]
Further, in spray coating, it is important that the supply of a pump for supplying a coating liquid is constant. In other words, if the supply of the liquid is not constant and has a pulsation, the pulsation directly affects the discharge amount of the liquid, so that the adhesion amount becomes uneven. Therefore, as a pump for supplying the liquid to the spray, it is preferable to use a multiple plunger pump in which pulsation is suppressed, a syringe-type super-precision discharge device, or the like.
[0167]
These methods may be used alone, but by combining a plurality of them, a more effective leveling is performed and a charge transport layer with reduced unevenness is formed.
Further, when the leveling is insufficient, it is possible to wear and smooth the convex portions of the charge transport layer as a method of reducing the unevenness. For example, a method in which a convex portion is detected by a film thickness meter and the portion is polished to eliminate the convex portion can be considered.
[0168]
In the present invention, in order to improve environmental resistance, and to prevent a decrease in sensitivity and a rise in residual potential, oxidation of each layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, and an intermediate layer is performed. Inhibitors, plasticizers, lubricants, UV absorbers, and low molecular charge transport materials can be added. Representative materials of these compounds are described below.
[0169]
Examples of the antioxidant that can be added to each layer include the following, but are not limited thereto.
[0170]
(A) Phenol compound
2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, n-octadecyl-3- (4'-hydroxy -3 ', 5'-di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl -6-t-butylphenol), 4,4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol) ), 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di- t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butylic acid C] cholesterol, tocopherols and the like.
[0171]
(B) paraphenylenediamines
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-tert-butyl-p-phenylenediamine and the like.
[0172]
(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.
[0173]
(D) Organic sulfur compounds
Dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like.
[0174]
(E) Organic phosphorus compounds
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.
[0175]
Examples of the plasticizer that can be added to each layer include the following, but are not limited thereto.
[0176]
(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.
[0177]
(B) Phthalate ester plasticizer
Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, dinonyl phthalate, dinononyl phthalate, phthalic acid Diisodecyl, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate and the like.
[0178]
(C) Aromatic carboxylate plasticizer
Trioctyl trimellitate, tri-n-octyl trimellitate, octyl oxybenzoate and the like.
[0179]
(D) Aliphatic dibasic ester plasticizer
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, n-octyl adipate-n-decyl, diisodecyl adipate, dicapry adipate, diazellate -2-ethylhexyl, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, Dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.
[0180]
(E) Fatty acid ester derivatives
Butyl oleate, glycerin monooleate, methyl acetyl ricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
[0181]
(F) Oxyacid ester plasticizer
Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.
[0182]
(G) Epoxy plasticizer
Epoxidized soybean oil, epoxidized linseed oil, butyl epoxystearate, decyl epoxystearate, octyl epoxystearate, benzyl epoxystearate, dioctyl epoxyhexahydrophthalate, didecyl epoxyhexahydrophthalate, and the like.
[0183]
(H) Dihydric alcohol ester plasticizer
Diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate and the like.
[0184]
(I) Chlorine-containing plasticizer
Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxy chlorinated fatty acid methyl and the like.
[0185]
(J) Polyester plasticizer
Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, etc.
[0186]
(K) sulfonic acid derivative
P-toluenesulfonamide, O-toluenesulfonamide, P-toluenesulfonethylamide, O-toluenesulfonethylamide, toluenesulfone-N-ethylamide, P-toluenesulfon-N-cyclohexylamide and the like.
[0187]
(L) Citric acid derivative
Triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, acetyl tri-2-ethylhexyl acetyl citrate, n-octyldecyl acetyl citrate and the like.
[0188]
(M) Other
Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.
[0189]
In the present invention, a lubricant can be added to each layer. Examples include, but are not limited to, the following.
[0190]
(A) Hydrocarbon compounds
Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, etc.
[0191]
(B) fatty acid compound
Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, etc.
[0192]
(C) Fatty acid amide compound
Stearyl amide, palmityl amide, olein amide, methylene bis stearoamide, ethylene bis stearoamide and the like.
[0193]
(D) Ester compound
Lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acid polyglycol esters.
[0194]
(E) Alcohol compounds
Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
[0195]
(F) Metal soap
Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
[0196]
(G) Natural wax
Carnauba wax, Candelilla wax, beeswax, whale wax, Ibota wax, Montan wax, etc.
[0197]
(H) Other
Silicone compounds, fluorine compounds, etc.
Examples of the ultraviolet absorber that can be added to each layer include the following, but are not limited thereto.
[0198]
(A) Benzophenone type
2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone and the like.
[0199]
(B) salicylate
Phenyl salicylate, 2,4-di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate and the like.
[0200]
(C) Benzotriazole type
(2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3′-tert-butyl5) '-Methylphenyl) 5-chlorobenzotriazole
[0201]
(D) cyanoacrylate-based
Ethyl-2-cyano-3,3-diphenyl acrylate, methyl-2-carbomethoxy 3 (paramethoxy) acrylate and the like.
[0202]
(E) Quencher (metal complex salt)
Nickel (2,2′thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate, and the like.
[0203]
(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.
[0204]
(toner)
As described above, toner production methods mainly include a pulverization method and a polymerization method. In the present invention, any of the production methods can be used. However, in terms of image quality characteristics and transferability, the average circularity is 0.94 to 0.995, the particle size is a spherical toner having a weight average particle size of 4 to 8 μm, and the minimum particle size is 3 μm or more. Is desirable.
[0205]
This is because when the surface roughness of the photoconductor surface layer, particularly the sum Ry of the maximum peak height Rp and the maximum valley depth Rv, is larger than the toner particle diameter D, the toner comes off under the cleaning blade. appear. Even if the toner particle size is 4 μm, a large amount of toner having a particle size of 4 μm or less is contained in the toner. This is because Ry (= Rp + Rv) may reach 3 μm during use of the photoconductor, and even if Ry is smaller than the minimum particle size D of the toner, the blade edge The distortion may cause a gap between the photosensitive member and the photosensitive member, and the toner may be removed under the cleaning blade, resulting in poor cleaning. The charging member may be stained or the image quality may be slightly stained.
[0206]
Further, the smaller the toner particle size, the larger the amount of charge of the toner, so that the developing ability is reduced, the image density is reduced, and in the case of color copying, there is a problem that it is difficult to obtain a sufficient image density. Occurs. Further, if the particle diameter is small, the toner particles may remain in the air for a long time when the toner is scattered, and there is a high possibility of causing health damage (respiratory system). Is not a good thing.
[0207]
The pulverization method uses a dry blender, a Henschel mixer, a ball mill, etc., mixes additives such as a colorant and a charge control agent into a binder polymer produced by polymerization, melts and kneads the resulting mixture to obtain a coarse mass. A method obtained by pulverizing, finely pulverizing and classifying with a sieve or the like can be sieved for each particle size.
[0208]
Although the pulverization method has an advantage that the toner can be finely divided, the cost is likely to increase because the process is complicated. If the degree of circularity is small (irregular shape), it is difficult to uniformly charge the particles, and transfer failure is likely to occur. In addition, when pressed against the photoreceptor by the cleaning blade, there is a tendency that scratches easily occur. By adjusting the particle size, charging stability and uniformity are enhanced, so it is preferable that the degree of circularity is as high as possible. However, there is a limit to increasing the degree of circularity, and usually about 0.92 to 0.94. Mostly used. Therefore, the sharpness of the character edge may be insufficient in the development or transfer of a dot pattern, or transfer omission may occur.
[0209]
In addition, even if a high resolution with good sharpness is obtained in the early stage, it is difficult to maintain, and when a copy of a copy (the second or third generation copy) is printed, the resolution becomes extremely poor, and it is not practical. There are points. For this reason, toners with even higher sphericity are being developed, but the cost is further increased, and the conversion to the polymerization method for toners, in which toner having a relatively uniform particle size is easily obtained, has been promoted. I have.
[0210]
Examples of the production method of the polymerization method include a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, a microcapsule polymerization method, and spray drying. For example, in the case of the suspension polymerization method, a binder resin is produced by homogenizing additives such as a colorant and a charge controlling agent, adding a dispersion medium and a dispersant, and polymerizing. Since the polymerization method has a simplified process, the production cost is lower than that of the pulverization method. Further, there is an advantage that the particle diameters are relatively well uniform, toner having a large or small particle diameter can be selectively produced, and irregularly shaped particles are scarcely produced (mostly spherical toner).
[0211]
Most of the particles produced by the polymerization method are spherical and have almost the same particle size, so that the charge can be easily made uniform and adhere to the latent image almost faithfully. Therefore, transfer efficiency tends to be high, high resolution can be easily obtained, and image reproducibility tends to be high. The preferable numerical value of the average circularity is 0.94 to 0.995, as described above, in which the cleaning property is sufficiently performed and a high-quality image having no problem in image quality is obtained. When the average circularity is 1.0 (true sphere), it is desirable to use a cleaning brush in combination. However, if it is 0.995, there is no practical problem.
[0212]
The toner for developing an electrostatic image is produced by using a binder resin, a colorant and a charge control agent as main components, and further adding a release agent. The following are examples of general binder resins, colorants, charge control agents, release agents, and external additives used in toner production.
[0213]
(1) Binder resin
Styrene, ethylene, propylene, butylene, vinyl acetate, vinyl benzoate, methyl acrylate, ethyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, ethyl methacrylate, methyl methacrylate, butyl methacrylate, vinyl methyl ether , Vinyl butyl ether, vinyl methyl ketone, vinyl isopropenyl ketone, vinyl hexyl ketone, vinyl propionate, isobutylene, chlorostyrene and other polymers or copolymers, polystyrene, polyethylene, polyester, styrene-acrylonitrile copolymer, styrene-methacrylic Known materials such as acid alkyl copolymer, styrene-butadiene copolymer, polypropylene, styrene-maleic anhydride, polyurethane, epoxy resin, and modified rosin are used. Kill.
[0214]
(2) Colorant
Carbon black, nigrosine dye, iron black, naphthol yellow S, hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, graphite, titanium yellow, polyazo yellow, oil yellow, hansa yellow ( GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Iso Indolinone Yellow, Bengala, Lead Tan, Lead Vermilion, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Para Chlor Ortho Nitroaniline Red, Risor Fast Scarlet G, Brillia Tofast Scarlet, Brilliant Carmine Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lisole Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Museum, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thio Indigo Maroon , Oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermillion, benzidine orange Perinone orange, oil orange, cobalt blue, Cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine , Navy blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold , Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Titanium Oxide, Leaf flower, lithopone and mixtures thereof can be used. The content of the colorant in the toner is usually 1 to 15% by weight, preferably 3 to 10% by weight.
[0215]
(3) Release agent
The toner of the present invention can contain a release agent together with a toner binder and a colorant, if necessary.
Various types of conventionally known release agents (waxes) can be used. Examples of such a material include polyolefin waxes (such as polyethylene wax and polypropylene wax); long-chain hydrocarbons (such as paraffin wax and sasol wax); and carbonyl group-containing waxes. Preferred among these are carbonyl group-containing waxes.
[0216]
Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18 Polyalkanol esters (such as tristearyl trimellitate and distearyl maleate); polyalkanoic acid amides (such as ethylenediamine dibehenyl amide); polyalkylamides (such as trimellitic acid tristearyl amide) And dialkyl ketones (such as distearyl ketone). Preferred among these carbonyl group-containing waxes are polyalkanoic esters.
[0217]
The melting point of the wax is usually from 40 to 160 ° C, preferably from 50 to 120 ° C, and more preferably from 60 to 90 ° C. A wax having a melting point of less than 40 ° C adversely affects heat-resistant storage stability, and a wax having a melting point of more than 160 ° C tends to cause cold offset during fixing at a low temperature. The melt viscosity of the wax is preferably 5 to 1000 cps, more preferably 10 to 100 cps, as a value measured at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps have poor improvement effects on hot offset resistance and low-temperature fixability.
[0218]
The content of the wax in the toner is usually from 0 to 40% by weight, and preferably from 3 to 30% by weight.
[0219]
(4) Charge control agent
The toner of the present invention can contain a charge control agent as needed.
Various known charge control agents can be used. Examples of such dyes include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, and quaternary ammonium salts (fluorine-modified quaternary ammonium salts). ), Alkyl amides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts. Specifically, bontron 03 of a nigrosine dye, bontron P-51 of a quaternary ammonium salt, bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, and E-82 of a salicylic acid metal complex 84, phenolic condensate E-89 (all manufactured by Orient Chemical Industries), quaternary ammonium salt molybdenum complex TP-302, TP-415 (all manufactured by Hodogaya Chemical Industry), quaternary ammonium Salt copy charge PSY VP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (all from Hoechst), LRA-901, LR-147, a boron complex (Nippon Carlit), copper phthalocyanine, perylene, quinacridone Azo pigments, sulfonate group, a carboxyl group, such as polymer compounds having a functional group such as quaternary ammonium salts.
[0220]
In the present invention, the amount of the charge control agent used is determined by the type of the binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is uniquely limited. However, it is preferably used in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the binder resin. Preferably, the range is 0.2 to 5 parts by weight. If the amount exceeds 10 parts by weight, the chargeability of the toner is too large, the effect of the main charge control agent is reduced, the electrostatic attraction with the developing roller increases, the fluidity of the developer decreases, and the image density decreases. Causes a decline.
[0221]
These charge control agents and release agents can be melt-kneaded together with the masterbatch and the resin, or of course, may be added when dissolved and dispersed in an organic solvent.
[0222]
(5) External additives
As the external additive for assisting the fluidity, developability and chargeability of the colorant-containing toner particles obtained in the present invention, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 μm to 2 μm, and particularly preferably 5 μm to 500 μm. The specific surface area by the BET method is 20 to 500 m. ² / G. The use ratio of the inorganic fine particles is preferably from 0.01 to 5% by weight of the toner, and particularly preferably from 0.01 to 2.0% by weight.
[0223]
Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, and diatomaceous Examples include earth, chromium oxide, cerium oxide, pengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
[0224]
In addition, polymer fine particles can be used. Examples of such materials include soap-free emulsion polymerization, suspension polymerization, and polystyrene obtained by dispersion polymerization, methacrylate and acrylate copolymers, silicone, benzoguanamine, and polycondensation systems such as nylon, and thermosetting resins. Polymer particles.
[0225]
Such an external additive can be subjected to a surface treatment to increase hydrophobicity and prevent deterioration of its flow characteristics and charging characteristics even under high humidity. Preferred surface treatment agents include, for example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oil, and modified silicone oil. It can be mentioned as.
[0226]
Incidentally, as a cleaning improver for removing the developer after transfer remaining on the photoreceptor and the primary transfer medium, for example, zinc stearate, calcium stearate, fatty acid metal salts such as stearic acid, for example, polymethyl methacrylate fine particles, Polymer fine particles produced by soap-free emulsion polymerization of polystyrene fine particles and the like can be mentioned. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 μm to 1 μm.
[0227]
(Cleaning member)
For the shape of the cleaning blade generally used, a strip-shaped elastic body (polyurethane rubber) having a plate thickness of about 1.5 to 3 mm is used in view of cost, and the rubber hardness is about 75 degrees in JIS hardness. The disadvantage of this cleaning blade is that since the rubber hardness of the portion that comes into contact with the photoreceptor is low, the blade edge is dragged in the rotation direction of the photoreceptor when sliding on the photoreceptor, so that line contact is likely to come into surface contact. For this reason, the tip of the blade is crushed, deformed, distorted, etc., and a slight gap is generated between the photoconductor and the blade, so that the toner is pinched between the blade and the photoconductor and is sent to the charging device. Occurs. That is, cleaning failure occurs. In such a situation, even if the pulverized toner has an irregular shape, the toner may be removed with a small particle size (for example, when the classification is not sufficient and the small particle size toner or the crushed toner is included). . FIG. 10 and FIG. 11 are schematic diagrams of toner loss.
[0228]
Toner loss is caused by the cleaning blade edge penetrating into the photosensitive layer due to insufficient photoconductor hardness, deformation due to insufficient cleaning blade hardness, the photoconductor during sliding contact due to the shape and hardness of the cleaning blade, and the friction coefficient of the photoconductor surface layer. And the contact pressure of the blade, the sphericity of the toner, and the surface roughness of the surface layer of the photoreceptor. When toner is removed, particles such as carrier and paper powder (such as talc) escape under the blade, scratches and toner filming are likely to occur, and the situation becomes even worse.
[0229]
In order to improve the toner removal, it is important to completely block the toner at the entrance (upstream side) of the cleaning blade, so that the edge of the cleaning blade is not deformed and no gap is formed on the surface of the photoconductor. It is important to have a configuration and a structure that makes it tightly adhered to.
[0230]
As one of these means, it is necessary to increase the degree of deformation resistance when the cleaning blade rubs the photoreceptor, and to make the structure resistant to deformation. For example, increasing the hardness of the cleaning blade. By reinforcing even low-grade materials, the degree of deformation resistance is increased. Another object is to minimize frictional resistance with the photoconductor.
[0231]
The meaning of increasing the hardness of the cleaning blade is as follows.
Abrasion of the photosensitive layer is a physical phenomenon that occurs because the surface of the photosensitive layer is repeatedly rubbed by the blade to break intermolecular bonds. The wear is much greater than with a single blade.
However, it is considered that the wear is greatly contributed by the movement of the photosensitive member, the vibration of the cleaning blade, and the phenomenon caused by the penetration of the toner and the carrier.
[0232]
For example, when a record is placed on an inaccurate record player and the diamond stylus is turned with a load of about 2 gr applied thereto, and when a record player with extremely high accuracy and almost no runout is turned, the diamond stylus is loaded with the load. When a load several times the load is applied, there is a fact that the latter has much less wear on the record disc, despite the large load. This phenomenon is interpreted as a phenomenon that occurs because the diamond needle vibrates vigorously left and right, and the vibration causes the diamond needle to cut molecules of the record. Therefore, it is important not only to prevent the toner from entering the cleaning blade, but also to prevent the blade edge portion from swinging violently with the rotation of the photoconductor.
[0233]
The cleaning blade has a knife-edge structure as shown in FIGS. 12, 14, and 16 and a strip shape as shown in FIGS. 13, 15, and 17 at a blade inlet side (upstream side). A cleaning blade having a structure in which a reinforcing plate of 0.5 to 1 mm of stainless steel (SUS), iron, brass, aluminum, polycarbonate resin, acrylic resin, or the like is attached can be suitably used. The thickness of these cleaning blades is desirably about 1 to 5 mm, and preferably 1 to 3 mm.
[0234]
An elastic member having a hardness of 75 to 90 degrees is desirable as the hardness of the cleaning blade. In the case of the knife-shaped cleaning blade shown in FIGS. 12, 14, and 16, the JIS-A hardness is preferably 80 to 90 degrees, and in the structure of FIGS. 13, 15, and 17, the JIS-A hardness is preferably 75 to 85 degrees. It is.
If the hardness is low, the tip of the blade is crushed due to the contact pressure of the cleaning blade pressure, and the blade comes into surface contact. This facilitates toner intrusion, and if the JIS-A hardness exceeds 90 degrees, the photoconductor is damaged. This is because the contact pressure cannot be increased, and a gap may be formed between the photosensitive member and the cleaning blade. Another reason is that it is easy to sneak into foreign substances such as toner.
[0235]
The shape of the tip of the cleaning blade shown in FIGS. 12, 14 and 16 is to prevent toner from sneaking in. When a strip-shaped cleaning blade having a low hardness is used, the tip of the blade is crushed due to the contact pressure and the frictional resistance between the cleaning blade and the photoconductor, and the toner is entrained. Knife edge is a means to avoid this phenomenon, and by keeping line contact with the photoreceptor, it does not cause deep scratches such as scratches on the photoreceptor, and keeps uniform shallow scratches It is.
[0236]
The knife-edge dimensions shown in FIGS. 12, 14 and 16 are such that the angle θ1 is sharply cut at an acute angle of 15 to 40 (degrees), and the free length L1 is 2 to 8 mm, preferably 3 to 6 mm. is there. On the other hand, in the strip-shaped cleaning blades shown in FIGS. 13, 15, and 17, the free length L2 is 4 to 8 mm, and L4 is 1 to 3 mm. The reinforcing metal plate extends to a position sandwiched by the supporting base except for L4 of 1 to 3 mm. If the free length is long, the strength of the blade against deformation is reduced, so that it is desirable to be as short as possible.
[0237]
The contact angle to the photoreceptor is set in the direction opposite to the rotation of the photoreceptor, that is, in the counter direction, and θ2 in FIGS. 16 and 17 is preferably 5 to 30 degrees.
In the case of the blades of the types shown in FIGS. 13, 15, and 17, when the cut faces the photoreceptor (in the direction of 90 degrees), the toner is crushed between the photoreceptor and the toner under the blade. It is not preferable because it easily penetrates into the water.
[0238]
As a means of fixing these tip-shaped blades, metals such as aluminum, phosphor bronze, iron and brass, resins such as polycarbonate, vinyl chloride, delrin, polyethylene terephthalate, and ceramic members such as alumina are processed into plates and casings. A cleaning blade can be attached, but a metal plate with a thickness of about 1 mm to 3 mm, such as a chromium-plated iron plate or an aluminum plate, is preferred from the viewpoints of workability, toughness, no temperature deformation, and rust resistance. .
[0239]
As shown in FIG. 12, the means for processing the support base and attaching the blade is a method of fitting and fixing the support base in a casing shape, bending a metal plate, and applying an adhesive (double-sided tape, one-component or two-part). Liquid adhesive, hot melt adhesive, etc.).
[0240]
As the elastic body used for the cleaning blade, there are polyurethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, neoprene rubber, and the like. However, polyurethane rubber is preferably used from the viewpoint of durability, repelling resilience and cleaning properties. Polyurethane rubber is mainly composed of a polyol, an isocyanate, and a curing agent.
[0241]
The polyurethane rubber is prepared by mixing a dehydrated polyol and an isocyanate, reacting the mixture at a temperature of 70 to 140 (° C.) for about 100 minutes, adding a curing agent to the prepolymer, and heating the prepolymer to 140 to 160 ° C. in advance. Place in the mold of the placed molding machine and cure for 50-60 minutes. After that, it is obtained by taking it out of the mold and cutting it to the required size with a cutting machine.
The polyurethane rubber used for the cleaning blade is cut obliquely with a cutting machine, or cut into a knife edge with a die as shown in FIG. 14, and then, as shown in FIG. It is cut straight and cut so that the thickness of the tip is 0.5 mm or less.
In a mold manufacturing method using this mold, it is relatively easy to manufacture as long as the mold is made.
The reason why the knife edge is defined to be 0.5 mm or less is to minimize the penetration of the toner under the blade by expanding the surface contact, and to maintain the line contact even when the photosensitive member is rotating. It is.
[0242]
The cleaning blade is held so as to abut on the photoconductor in the counter direction (so as to abut evenly). Here, “equally abutting” means that the load of the cleaning blade on the photoconductor is uniform over the longitudinal direction of the photoconductor. In this case, it is desirable that local distortion of the blade edge does not occur.
Since the contact pressure (linear pressure) at which the edge of the blade contacts the photoconductor is higher than the hardness of a commonly used blade, the contact pressure (linear pressure) is set to 15 g / cm to 40 g / cm. However, in consideration of the cleaning property and the scratch imparted to the photoreceptor, it is preferably set to 15 g / cm or more and 25 g / cm or less. At 15 g / cm or less, when a blade having a high JIS-A hardness is used as a blade, a gap is generated between the cleaning blade and the photoconductor even if there is a small amount of foreign matter depending on the surface roughness of the photoconductor, and the cleaning is performed. Failure may occur.
On the other hand, if it is set higher than 25 g / cm, the photoreceptor may be scratched by the blade because the hardness is higher than that of the conventional product. However, only a small amount of scratching usually occurs, but hard foreign matter does not stick into the photoreceptor, and this does not mean that the blade cannot be used immediately except when the blade edge is damaged.
[0243]
When the cleaning blade in such a state is used, even if the spherical toner has an average circularity of 0.95 or more, particularly 0.98 or more, it is necessary to clean the toner well enough to cause no practical problem. Becomes possible.
[0244]
(Coefficient of friction of photoconductor and reduction method)
Maintaining the friction coefficient of the photosensitive layer surface at a low level is effective for improving the wear resistance of the photosensitive layer, improving the transferability of a visualized toner image, and improving the cleaning property with a cleaning blade. That is, an effect of reducing the sliding friction pressure of the cleaning blade against the photoconductor and relaxing the adhesion of the toner to the photoconductor is provided. Therefore, the surface layer of the photoreceptor is less likely to be damaged, and when toner and carrier are sufficiently blocked by the cleaning blade, abrasion of only the cleaning blade is caused, and further application of a lubricant may reduce abrasion. I can do it.
[0245]
As a means for reducing the friction coefficient, an external addition method of applying a lubricant to the surface layer of the photoreceptor (an example of applying a lubricant scraped off with a brush to the photoreceptor is shown in FIG. 3. 201: lubricant, 202: lubrication Brush is applied over the outermost few microns of the photosensitive layer by the internal addition method of containing a lubricant. The latter means that the corona product acts on the surface of the photoreceptor and the action of the lubricant The former method is better in terms of effect.
[0246]
In the external addition method, a substance exhibiting lubricity such as polytetrafluoroethylene, polyvinylidene fluoride, zinc stearate or the like can be applied to the surface of the photoreceptor by direct or indirect means. As a direct method, a powdery lubricant is incorporated in a bag, or a sheet-like lubricant is applied while being rubbed on the surface of the photoreceptor. There is a method of dispersing about 0.2% or arranging a lubricant, a brush, and a photoreceptor in this order, and applying a lubricant scraped off with a brush to the photoreceptor.
[0247]
When a lubricant is applied to the photoreceptor, the friction coefficient of polytetrafluoroethylene can be easily reduced from 0.6 to 0.2 or less. However, if the coefficient of friction is too low, the corona product adhered to the photoreceptor will not be scraped off, causing image deletion or toner adhering to the corona product film, making toner filming more likely. , Image flow may occur. Therefore, the coefficient of friction for preventing image deletion is 0.3 to 0.5 at the initial value set in the image forming apparatus, and the coefficient of friction after 100 copies is at least 0.3 or more. The upper limit is desirably 0.45 or less from the viewpoints of maintenance of cleaning properties, improvement of abrasion resistance, and maintenance of high-quality images. Of course, even if it temporarily exceeds 0.45, there is no practical problem.
[0248]
When the lubricant is not applied, the friction coefficient rapidly increases even with the photoreceptor having about 0.2 at the initial stage, and the friction coefficient reaches about 0.6 in 20 to 30 sheets. This is because not only abrasion of the photosensitive layer but also cleaning failure and transfer failure are likely to occur.
[0249]
Normally, in the case of an organic photoreceptor or a photoreceptor having a filler content of 10% by weight or less without a lubricant, the coefficient of friction is about 50 sheets from the start of copying. However, as the amount of the filler added increases, the particle size increases, and the coefficient of friction tends to fall below 0.6. When the lubricant is externally added to the photoreceptor, the friction coefficient largely fluctuates due to the application means. However, if the lubricant is normally supplied and the control performance is good, the friction coefficient which has once increased also starts to decrease, and 100 to 200 sheets It can be maintained at an almost stable level between the two. Therefore, if the coefficient of friction specifies 100 sheets passing, it is possible to predict a certain trend of the coefficient of friction thereafter.
[0250]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The parts here are on a weight basis.
[0251]
Preparation of electrophotographic photoreceptor for evaluation:
1) Preparation of photoreceptor having filler non-dispersed charge transport layer
The photoreceptor having the filler non-dispersed charge transport layer for evaluation was prepared by the following means.
A JIS3003 aluminum alloy drum having a diameter of 30.0 mm, a length of 340 mm, and a thickness of 0.750 mm was used as a conductive support, followed by dip coating with an undercoat layer (UL) coating solution having the following composition, and then at 120 ° C. for 20 minutes. The coating was dried and coated with a 3.5 μm undercoat layer, and then a coating solution for a charge generation layer (CGL) using the charge generation material described in Chemical Formula 1 below. A 2 μm charge generation layer was formed. Further, after applying the dip coating to the coating liquid for the charge transport layer (CTL) using the charge transport material described in Chemical Formula 2, changing the pulling speed condition, and coating the filler non-dispersed charge transport layer, The resultant was dried by heating at 130 ° C. for 20 to 30 minutes to produce an organic photoreceptor having a filler non-dispersed charge transporting layer having a film thickness varied between 2 μm and 35 μm.
[0252]

[0253]
(Coating solution for charge generation layer)
Bisazo pigment of the following structure 10 parts
Embedded image

Polyvinyl butyral 2 parts
200 parts of 2-butanone
Cyclohexanone 400 parts
[0254]

Embedded image

[0255]
2) Production of photoreceptor having filler-dispersed charge transport layer
The organic photoreceptor coated with the filler non-dispersed charge transport layer was dried by heating and then cooled, and subsequently, the filler dispersed charge transport layer was applied to a thickness of 2 to 10 μm by a spray coating method.
Here, the reason why the filler-dispersed charge transport layer was subsequently applied after cooling was that the interface was dissolved due to the solvent and a clear interface was not formed, but there was almost no problem if left overnight. However, if left for several weeks, the surface level changes due to oxidation or the like, and a barrier (capture level) is locally formed, which is likely to adversely affect image quality.
[0256]
On the filler non-dispersed charge transport layer, a binder resin (bisphenol Z-type polycarbonate resin) described below and a low molecular charge transport material (donor) having a primary particle size of 0.2, 0.3, 0.5, 0.7 And 5 μm of inorganic filler (α-alumina) of 1 μm are prepared, each inorganic filler, a dispersing aid and a solvent are put into a glass pot, and dispersed for 24 hours by a ball mill to prepare a coating liquid, and a spray method is used. And reciprocated 1 to 5 times to apply a filler-dispersed charge transport layer. After touch drying, the coating was dried by heating at 150 ° C. for 20 minutes to prepare an electrophotographic photosensitive member for evaluation having a filler-dispersed charge transport layer.
[0257]

Embedded image

[0258]
Table 1 shows a list of characteristics of the produced photoreceptor.
[0259]
[Table 1]

[0260]
Charging member:
1) Charging member for contact charging
In the charging member according to the embodiment of the present invention, carbon was uniformly dispersed in a 6 mm brass lot rod, and the electric resistance was 6 × 10 ⁵ Epichlorohydrin rubber adjusted to Ω · cm (when 100 VDC is applied) is applied so as to have a thickness of 3 mm and polished, and carbon, silica and fluororesin are dispersed on the epichlorohydrin rubber to form an electric resistance of (3 to 5) x 10 ⁸ Epichlorohydrin rubber prepared so as to have a resistivity of Ω · cm (when 100 VDC is applied) is uniformly applied to a thickness of 1 mm to form a shape of φ14 mm × 314 mm (effective charging width: 312 mm). (Electrophotographic copier, used for Ricoh Imagio MF2200)
[0261]
2) Charging member for non-contact charging
Charging member-1
8mm brass lot rod with electric resistance (4-6) × 10 ⁵ Epichlorohydrin rubber in which carbon, silica, and fluororesin dispersed at Ω · cm (when 100 VDC is applied) is applied to a brass lot rod of φ6 mm so as to have a thickness of 1 mm, φ14 mm × 314 mm (effective charging width: 312 mm) Was prepared. A non-contact charging member was prepared in which 1.5 mm inward from both ends of the charging member was attached with PET (polyethylene terephthalate) cut into a rhombus having a thickness of 49 μm, a width of 8 mm and a length of 31 mm, and used as a spacer. The distance between the photoconductor and the charging member was 56 μm on average. (Used for electrophotocopier Imagio MF2200)
[0262]
Charging member-2
8mm brass lot rod with electric resistance (4-6) × 10 ⁵ Epichlorohydrin rubber in which carbon, silica, and fluorocarbon resin dispersed at Ω · cm (when 100 VDC is applied) is applied to a brass lot rod of φ6 mm so as to have a thickness of 1 mm, φ10 mm × 327 mm (effective charging width: 308 mm) Was prepared. A non-contact charging member was prepared in which 1.5 mm inward from both ends of the charging member was attached with PET (polyethylene terephthalate) cut into a rhombus having a thickness of 49 μm, a width of 8 mm and a length of 31 mm, and used as a spacer. The distance between the photosensitive member and the charging member was 53 μm on average.
(Used for the color laser beam printer IPSIOR 8000)
[0263]
Method of reducing friction coefficient of photoconductor surface layer:
In the present invention, a method was used in which 0.03% by weight of zinc stearate was added to the toner to provide a lubricant to the surface layer of the photoreceptor via the developer.
[0264]
Developer = carrier + toner:
As the carrier, a magnetic carrier (FPC-300LC) having a weight average particle size of 58 μm was used.
The toner is a cyan, magenta, yellow and black spherical toner having a weight average particle diameter of about 5.1 to 5.6 μm and an average circularity of 0.987 to 0.993, manufactured using the following manufacturing examples. It was used.
As for the toner manufactured by the pulverization method, a black toner having a weight average particle diameter of 5.2 μm to 7.5 μm (minimum particle diameter: 2.8 μm to 4.1) and an average circularity of 0.914 to 0.93 is used. It was used.
These toners were added at a ratio of 6.5% by weight to the carrier to form a developer.
To reduce the friction coefficient of the surface layer of the photoreceptor, zinc stearate was added to these toners in an amount of 0.03% by weight based on the total weight of the toner.
[0265]
Next, production examples of a polymerized toner (meaning a toner produced by a polymerization method) and a pulverized toner will be described.
[0266]
[Production Example of Polymerized Toner]
(1) Production example of cyan (C) toner
(Production example of additive polyester resin)
690 parts of bisphenol A ethylene oxide 2 mol adduct and 230 parts of terephthalic acid were polycondensed at 210 ° C. for 10 hours under normal pressure in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introducing pipe, and then a pressure reduction of 10 to 15 Torr. After reaction for 5 hours, the mixture was cooled to 160 ° C., and 18 parts of phthalic anhydride was added thereto and reacted for 2 hours to obtain an unmodified polyester resin (weight average molecular weight Mw: 85,000).
[0267]
(Example of prepolymer production)
800 parts of bisphenol A ethylene oxide 2 mol adduct, 160 parts of isophthalic acid, 60 parts of terephthalic acid, and 2 parts of dibutyltin oxide were placed in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introducing pipe. After reacting for 8 hours at a temperature of 10 ° C. and further dehydrating at a reduced pressure of 10 to 15 mmHg for 5 hours, the mixture was cooled to 160 ° C., and 32 parts of phthalic anhydride was added thereto and reacted for 2 hours. Next, the mixture was cooled to 80 ° C. and reacted with 170 parts of isophorone diisocyanate in ethyl acetate for 2 hours to obtain an isocyanate group-containing prepolymer (Mw: 35,000).
[0268]
(Example of production method of ketimine compound)
30 parts of isophoronediamine and 70 parts of methyl ethyl ketone were charged into a reaction vessel equipped with a stirring rod and a thermometer, and reacted at 50 ° C. for 5 hours to obtain a ketimine compound.
[0269]
(Example of toner production)
In a beaker, 14.3 parts of the above prepolymer, 55 parts of polyester (a), and 78.6 parts of ethyl acetate were stirred and dissolved. Then, 10 parts of rice wax (melting point: 83 ° C.) as a release agent and 4 parts of copper phthalocyanine blue pigment were added, and the mixture was stirred at 40 ° C. using a TK homomixer at 12,000 rpm for 5 minutes, and then 20 minutes by a bead mill for 30 minutes. Crushed at ℃. This is referred to as a toner material oil dispersion.
[0270]
306 parts of ion-exchanged water, 265 parts of a 10% suspension of tricalcium phosphate, and 0.2 part of sodium dodecylbenzenesulfonate are placed in a beaker, and the aqueous dispersion is carried out while stirring the TK homomixer at 12000 rpm. To the liquid (1), the above-mentioned oil dispersion of the toner material and 2.7 parts of the ketimine compound were added, and the mixture was reacted while stirring was continued.
[0271]
After removing the organic solvent from the dispersion liquid after the reaction (viscosity: 3500 mP · s) at a temperature of 50 ° C. or less within 1.0 hour under reduced pressure, filtration, washing and drying are performed, and then air classification is performed to form a spherical particle. Toner base particles were obtained.
[0272]
Next, 100 parts of the obtained base particles and 0.25 part of a charge controlling agent (Bontron E-84 manufactured by Orient Chemical Co., Ltd.) were charged into a Q-type mixer (manufactured by Mitsui Mining Co., Ltd.), and the peripheral speed of the turbine blade was set to 50 m / m. sec and mixed. In this case, the mixing operation was performed for 5 minutes, with a 2-minute operation and a 1-minute pause, for a total processing time of 10 minutes.
Further, 0.5 part of hydrophobic silica (H2000, manufactured by Clariant Japan) was added and mixed. In the mixing operation in this case, the peripheral speed was set to 15 m / sec, and the mixing was performed for 30 minutes and a 1-minute pause for 5 cycles.
As described above, a cyan toner was obtained. The weight average particle size was 5.1 μm (minimum particle size: 4.7 μm) and the average circularity was 0.993.
[0273]
(2) Production example of magenta toner
(Preparation of magenta masterbatch particles)
600 parts of water
Pigment Red 57 water-containing cake (50% solids) 200 parts
Is stirred well with a flasher. To this, 1200 parts of a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 3500, Mw / Mn; 4.0, Tg; 60 ° C.) was added, and kneaded at 150 ° C. for 30 minutes. In addition, after further kneading for 1 hour, removing water and xylene, rolling and cooling, pulverizing with a pulperizer, and further 2 passes with a three-roll mill, magenta master batch pigment (MB1-M) (average particle size about 0.2 μm) Got.
[0274]
(Example of prepolymer production)
856 parts of bisphenol A ethylene oxide 2 mol adduct, 200 parts of isophthalic acid, 20 parts of terephthalic acid, and 4 parts of dibutyltin oxide were placed in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introducing pipe. After reacting for 6 hours at 50 ° C and dehydrating at a reduced pressure of 50 to 100 mmHg for 5 hours, the mixture was cooled to 160 ° C, and 18 parts of phthalic anhydride was added thereto and reacted for 2 hours. Then, the mixture was cooled to 80 ° C. and reacted with 170 parts of isophorone diisocyanate in ethyl acetate for 2 hours to obtain an isocyanate group-containing prepolymer (Mw: 25,000).
[0275]
(Example of toner production)
15.4 parts of the above prepolymer, 50 parts of a polyester resin, and 95.2 parts of ethyl acetate were placed in a beaker, and dissolved by stirring. Next, 10 parts of carnauba wax (molecular weight 1800, acid value 2.5, needle penetration 1.5 mm / 40 ° C.) and 10 parts of the masterbatch particles were added, and the mixture was stirred at 85 ° C. with a TK homomixer at 10,000 rpm. Thereafter, the mixture was wet-pulverized by a bead mill in the same manner as in Example 1 to obtain an oil-based dispersion of a toner material.
[0276]
Then, spherical mother toner particles were obtained in the same manner as in Example 1 except that the aqueous dispersion obtained in the same manner as in Example 1 was used.
Next, a magenta toner was obtained in the same manner as in the production example of the cyan toner, except that Bontron E-84 manufactured by Orient was changed to E-89 as a charge control material. The weight average particle size was 4.8 μm (minimum particle size: 3.6 μm), the average circularity was 0.991.
[0277]
(3) Production example of yellow (Y) toner
A yellow toner was obtained in the same manner as in the above production method except that the pigment was changed to Hansa Yellow 10G.
The weight average particle size was 5.5 μm (minimum particle size: 4.2 μm) and the average circularity was 0.991.
[0278]
(4) Production example of black (Bk) toner
The pigment was changed from copper phthalocyanine to carbon black, and a black toner was produced in the same manner as in the above production method. The obtained toner had a weight average particle size of 5.6 μm (minimum toner: 4.5 μm) and an average circularity of 0.993. Further, by changing the conditions, a toner having a weight average particle size of 3.8 μm (minimum toner: 3.1 μm) and an average circularity of 0.987 was produced.
[0279]

After melt-kneading using the composition extruder, the cooled kneaded material is mechanically pulverized, and the coarsely pulverized product is finely pulverized by colliding with a collision plate using a jet stream, and then subjected to particle size classification with an airflow classifier. Classification was performed every time, and the weight average particle diameter was 5.2 μm (minimum particle diameter: 2.8 μm), 6.3 μm (minimum particle diameter: 3.2 μm), and 7.5 μm (minimum particle diameter: 4.1 μm). A black toner was obtained. () Shows the minimum particle size toner. The average circularity was 0.91 to 0.93.
[0280]
Similarly, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Yellow 17, C.I. I. Pigment Red 202 was used to obtain a cyan toner, a yellow toner, and a magenta toner, respectively.
[0281]
[Cleaning blade]
Cleaning blade [Type 1]
Three types of polyurethane rubber cleaning blades having a JIS-A hardness of 74 degrees, 81 degrees, and 87 degrees were produced by die molding. The dimensions after the formation are a trapezoidal shape (the shape is as shown in FIG. 18) having a plate thickness of 2.8 mm, a width of 15 mm, a length of 320 mm, and a length of the oblique cut portion of 4 mm. The burr at the contact portion with the photoreceptor was cut, and the width of the cut portion was about 0.3 mm. The measurement of JIS-A hardness used GS-701N manufactured by TECLOCK, manufactured according to JIS K6301. A conductive paint (Fujikura Kasei Dotite) was thinly melted with a thinner, applied to the entire oblique cut side, and dried. Resistance is 2.8 × 10 when 100V is applied ⁵ Ω · cm.
[0282]
The oblique cut portion is directed upstream (toward the transfer device) in the rotation direction of the photoconductor on a 363-mm-long support base obtained by bending the blade so as to be in contact with the photoconductor at an angle of 8 degrees at a plate thickness of 0.8 mm. Then, using a two-part epoxy adhesive (Araldite 8254-01, Vantico), the free length L1 was adhered to be 5 mm, and a conductive paint was applied to the end of the support base and the end. The surface was subjected to conduction (） 0Ω) treatment at five places with the conductive paint dootite to complete a cleaning member. (Used for Ricoh's Imagio MF2200 for electrophotographic copying machines)
[0283]
Cleaning blade [Type 2-1]
A JIS-A hardness of 71 degrees, 77 degrees, and 87 degrees, a polyurethane rubber having a thickness of 1 mm and a thickness of 2 mm was cut into a strip having a width of 15 mm and a length of 320 mm. A conductive paint (Doitite manufactured by Fujikura Kasei) was applied and dried sufficiently. Resistance is 2.8 × 10 when 100V is applied ⁵ Ω · cm. A hard aluminum plate cut to a thickness of 13.5 mm x 320 mm with a thickness of 0.1 mm is removed from this polyurethane rubber by 1.5 mm from the tip that comes in contact with the photoreceptor, and is adhered with a strong double-sided tape. Conduction treatment was performed on the surface of the applied conductive paint with another dootite at five places.
[0284]
The cleaning blade obtained in this manner was processed to be able to abut against the photoreceptor at an angle of 8 degrees, and a strong double-sided tape was applied to an iron member having a sheet thickness of 1 mm and a length of 363 mm bent into a square shape. Then, a cleaning blade having a shape shown in FIG. 13 or FIG. 15 was produced. (Used for Imagio MF2200 for electrophotocopiers)
[0285]
Cleaning blade [Type 2-2]
After cutting a polyurethane rubber having a JIS-A hardness of 77 degrees and a thickness of 1 mm into a strip having a width of 10 mm and a length of 325 mm, a conductive paint (Fujikura Kasei Co., Ltd., Dotite) and dried sufficiently. Resistance is 3.5 × 10 when 100V is applied ⁵ Ω · cm. A hard aluminum plate cut to 8.5 mm x 325 mm with a thickness of 0.1 mm is detached from this polyurethane rubber by 1.5 mm from the tip that comes in contact with the photoreceptor, and is adhered with a strong double-sided tape. Conduction treatment was performed on the surface of the applied conductive paint with another dootite at five places.
[0286]
The cleaning blade obtained in this manner is processed into an L-shaped iron jig having a plate thickness of 1 mm and a length of 325 mm, which is processed to be able to abut on the photoreceptor at an angle of 8 degrees with an epoxy two-liquid type. A cleaning blade having the shape shown in FIG. 13 or FIG. 15 was produced by bonding using an adhesive (Araldite 8254-01 Bantico). (Used for Ricoh's color laser beam printer, Ipsiocolor 8000)
[0287]
Cleaning blade [Type 3 (Genuine cleaning blade)]
A JIS-A hardness of 77 degrees (genuine cleaning blade), hot strip of 2mm thick, 15mm wide, 320mm long strip-shaped polyurethane rubber is processed into an iron member with a 1mm thick, 363mm long square shape. It was attached with melt adhesive. The free length is 8 mm. In the case of Type 3, no conductive paint was applied.
[0288]
Evaluation method:
As an evaluation machine for the photoconductor and the cleaning blade, a dry charging type incorporating a process unit in which a photoconductor, a developing device, and a cleaning blade are integrated with a contact charging system using an LD element with an oscillation wavelength of a light source of 655 nm. A quadruple tandem-type color laser beam printer [CLBP] (Ipsiocolor) incorporating an electrophotographic copying machine (Imagio MF2200, manufactured by Ricoh) and a process unit that integrates a non-contact charging system, a photoconductor and a cleaning blade. 8000, manufactured by Ricoh Co., Ltd.).
[0289]
In the electrophotographic copying machine prepared for evaluation, since the high-voltage power supply to the charging device is a DC voltage, a high-voltage power supply (type HV-255 manufactured by Nagano Aichi Electric Co., Ltd.) capable of superimposing an AC voltage is separately prepared and standardized. The evaluation was performed while switching to the DC power supply.
When applying an AC superimposed DC voltage to the charging member, the AC voltage was fixed at 1500 V / 1350 Hz, the DC voltage was adjusted, and the dark portion potential at the developing device position was set.
The color laser beam printer was used in the standard setting (default) state and evaluated.
[0290]
The evaluation number was 50,000 sheets (A4 size) for each A4 size, and the film thickness of the initial photosensitive layer and the film thickness after 50,000 sheets were measured using an eddy current film thickness meter (Fisher type MMS). The wear amount of the layer was evaluated.
[0291]
Pencil hardness was measured by using a pencil scratch tester (surface property measuring device HEIDON-14 type, manufactured by Shinto Kagaku Co., Ltd.) and a JIS standard pencil (Mitsubishi Pencil "Uni") manufactured based on JIS K5401. Using a weight of 100 g, the photoreceptor prepared for measurement was cut into a size of 50 × 80 (mm) and measured.
The roundness and straightness were measured using a surface roughness measuring device (Surfcom 1400D manufactured by Tokyo Seimitsu Co., Ltd., pickup: E-DT-S02A) at 13 places in the longitudinal direction of the photoreceptor and at 4 places at 90 ° in the circumferential direction.
[0292]
The coefficient of friction was measured by fixing the photoreceptor to be measured to a pedestal and using a high-quality paper (manufactured by Ricoh Co., Ltd., type 6200 paper, using vertical grain) as a belt with a width of 30 mm, a length of 290 mm and a thickness of 85 μm Is placed in the circumferential direction of the photoreceptor, a 100 gr weight is attached to one end of the belt, a digital force gauge for weight measurement is attached to the other end, and the digital force gauge is slowly pulled to move the belt. The weight at the start was read, and the (static) friction coefficient μs was calculated from the following equation derived from Euler's method.
μs = 2 / π × ln (F / W)
Where μs: coefficient of static friction, F: reading load
W: Weight of weight π: Pi
[0293]
When the image quality evaluation is performed using an electrophotographic copying machine, the image quality evaluation uses a test sheet (manufactured by Kodak) prepared in accordance with JISZ 6008 to evaluate the resolution, and a Ricoh test prepared separately. The reproducibility of the dot pattern and the evaluation of the background stain were carried out on the chart.
[0294]
On the other hand, when evaluating with a color laser beam printer (non-contact charging method-AC voltage superimposed DC voltage application method), the resolution, the reproducibility of one dot pattern, noise , Color unevenness and the like were evaluated.
[0295]
The originals during the paper-running run other than during the evaluation used an image pattern with an image area of 6% in both evaluation machines, and the paper-running was performed in an environment of 22 to 24 (° C) / 58 to 65 (% RH).
The evaluation was carried out in the initial stage, after 100 sheets (only friction coefficient measurement), and after 50,000 sheets.
[0296]
(Examples 1 to 8)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 4 (Examples 1 and 2), 6 (Examples 3 and 4); 7 (Examples 5 and 6); 8 (Examples 7 and 8), and an electrophotographic copying machine (IMAZIO MF2200) were prepared. A charging member for a contact charging device was used for charging, and the voltage conditions applied to the charging member were a DC voltage of -628 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run. The developing bias was set to -500V. Since the image portion potential was -90 V to -105 V, the contrast potential was 410 to 395 V, which was a sufficient potential difference for image formation.
[0297]
A 1 mm-thick cleaning blade [Type 2-1] manufactured by adjusting these photoconductors to a JIS-A hardness of 87 degrees is mounted, and the contact pressure against the photoconductor is 23.5 g / cm. It was set in the photoreceptor unit of the electrophotographic copying machine for evaluation. The cleaning blade is automatically grounded by screwing.
[0298]
The toner has (1) an average circularity of 0.922, an average particle diameter of 6.3 μm, a minimum particle diameter of 3.2 μm, and (2) an average circularity of 0.93, an average particle diameter of 7.5 μm, and a minimum particle diameter of 4.1 μm. Was used, and 6.5% by weight of the carrier was mixed. The lubricant was not added to the toner, and the evaluation number was 50,000.
[0299]
Table 2 shows the evaluation results.
[0300]
In the cleaning blade of the present invention, Only the photoreceptor in which the filler No. 4 was not dispersed caused a slight cleaning failure to the extent that it did not affect the image, but the other photoreceptors were sufficiently blocked with toner, and the surface roughness of the photoreceptor was low. The deterioration was small. Therefore, there was almost no toner detachment phenomenon, and good results were obtained. The image quality was good because the image roughness was small, and although not described in the table, the resolution was sometimes 7.1 to 8.0 (lines / mm) in some cases using small particle size toner. ), And the reproducibility of one dot was also good.
No. The cleaning failure occurred in No. 4 not because of the surface roughness but because the friction coefficient of the photoreceptor was as large as 0.62 or more. It is considered that distortion (about 3 μm) was generated to the extent that it was generated. No. The reason why the judgment was 4 in 4 was that the amount of wear was large, but no particular problem was confirmed in image quality.
[0301]
[Table 2]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0302]
(Examples 9 to 14)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 4 (Examples 9 and 10); 6 (Examples 11 and 12); 8 (Examples 13 and 14) and three electrophotographic copying machines (IMAZIO MF2200) were prepared. The charging conditions used were charging member-1 for a non-contact charging device, and the voltage conditions applied to the charging member were a DC voltage of -635 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run.
A 2.8 mm-thick knife-edge cleaning blade [Type 1] manufactured by adjusting these photoconductors to a JIS-A hardness of 87 degrees was mounted, and the contact pressure against the photoconductor was 22.0 g / cm. Thus, it was set in a photoconductor unit of an electrophotographic copying machine for evaluation. The cleaning blade is configured to be automatically grounded by screwing.
[0303]
The toner has (1) an average circularity of 0.922, an average particle diameter of 6.3 μm, a minimum particle diameter of 3.2 μm, and (2) an average circularity of 0.93, an average particle diameter of 7.5 μm, and a minimum particle diameter of 4.1 μm. Using two types of pulverized black toners, 6.5% by weight of the carrier was mixed. The lubricant was not added to the toner.
[0304]
Table 3 shows the evaluation results.
When a cleaning blade having a knife-edge shape in contact with the photoreceptor was used, the toner was almost completely blocked. Therefore, the surface of the photoreceptor was only scratched by the blade, but the surface roughness Ry was not locally increased, and the cleaning failure was suppressed to a level that did not cause any problem even after 50,000 sheets.
In addition, No. The judgment of the sample No. 4 is △ because there is a lot of abrasion, and there is no problem in terms of image quality at 50,000 sheets, and since the abrasion is almost average, Ry is small and toner loss Was none.
No. In the sample marked with 8 in sample 8, the character image was slightly thickened in character, but at a practically negligible level.
[0305]
[Table 3]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0306]
(Comparative Examples 1 to 6)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 7 (Comparative Examples 1 and 2); No. 8 (Comparative Examples 3 and 4), 9 (Comparative Examples 5 and 6) and an electrophotographic copying machine (Imagio MF2200 manufactured by Ricoh Company) were prepared. Charging member-1 for a non-contact charging device was used for charging, and the voltage conditions applied to the charging member were a DC voltage of -635 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run.
[0307]
These photoconductors are equipped with a cleaning blade [type 3] made of polyurethane rubber having a JIS-A hardness of 77 degrees, and an electrophotographic image for evaluation so that the contact pressure against the photoconductor becomes 23.5 g / cm. It was set in the photoconductor unit of the copying machine. No conductive treatment is performed on the blade.
[0308]
The toner has (1) an average circularity of 0.914, an average particle size of 5.2 μm, a minimum particle size of 2.8 μm, and (2) an average circularity of 0.922, an average particle size of 6.3 μm, and a minimum particle size of 3.2 μm. And 6.5 wt% with respect to the carrier. The lubricant was not added to the toner.
[0309]
Table 4 shows the results.
If the blade has no reinforcement and the toner particle size is small, around 3 μm, the friction coefficient of the surface of the photoreceptor is high, so that the edge of the blade that contacts the photoreceptor is liable to be distorted and the toner is not removed. As a result, the surface of the photoreceptor was roughened, and a situation was apt to occur, in which toner was likely to be removed. Therefore, the surface roughness Ry was further increased. . In particular, when the particle size of the filler added to the charge transport layer is 1 μm, the number is numerically No. Although the value is close to that of the sample No. 8, it is presumed that one factor of x is that the roughness of the surface was conspicuous overall and the blade was easily distorted.
[0310]
[Table 4]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0311]
(Examples 15 to 22)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. No. 6 (Examples 15 and 16), 7 (Examples 17 and 18); 8 (Examples 19 and 20), 9 samples (Examples 21 and 22) and an electrophotographic copying machine (IMAZIO MF2200) were prepared. Charging member-1 for a non-contact charging device was used for charging, and the voltage conditions applied to the charging member were a DC voltage of -635 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run.
[0312]
A cleaning blade [Type 1] manufactured by adjusting the hardness of these photoconductors to 87 degrees is mounted, and an electrophotographic copying machine for evaluation is mounted so that the contact pressure against the photoconductor becomes 22.0 g / cm. It was set on the photoreceptor unit. The cleaning blade is configured to be automatically grounded by screwing.
[0313]
The toner has (1) an average circularity of 0.987, an average particle size of 5.6 μm, a minimum particle size of 4.5 μm, and (2) an average circularity of 0.992, an average particle size of 3.8 μm, and a minimum particle size of 3.1 μm. Was used, and 6.5% by weight of the carrier was mixed with the carrier. The lubricant was not added to the toner.
Table 5 shows the results of these evaluations.
Even when the toner was changed to a polymerized toner having a large circularity, good cleaning properties were exhibited. This is presumably because the edge of the cleaning blade hardly deformed, and there was no portion for pressing the toner against the photoreceptor, and there was no gap due to no lifting of the blade. As a result, the roughness of the photosensitive layer surface roughness was relatively suppressed, and the image quality was good. In particular, the resolution was sharper than that of the pulverized toner, and the fluctuation of the character edge was hardly observed. The resolution was as high as 7.1 to 9.0 lines / mm. In addition, although there was a slight omission of characters at the intersections of the line images, the result was good enough to cause no problem in practical use.
[0314]
[Table 5]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0315]
(Comparative Examples 7 to 12)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. No. 6 (Comparative Examples 7 and 8), 7 (Comparative Examples 9 and 10); 8 (Comparative Examples 11 and 12) and an electrophotographic copying machine (IMAZIO MF2200) were prepared. Charging member-1 for a non-contact charging device was used for charging, and the voltage conditions applied to the charging member were a DC voltage of -635 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run.
[0316]
These photoconductors were equipped with a cleaning blade [type 2-1] made of polyurethane rubber having a JIS-A hardness of 71 degrees, and were used for evaluation so that the contact pressure against the photoconductor was 23.5 g / cm. It was set in the photoconductor unit of the electrophotographic copying machine.
[0317]
The toner has (1) an average circularity of 0.993, an average particle size of 5.6 μm, a minimum particle size of 4.5 μm, and (2) an average circularity of 0.987, an average particle size of 3.8 μm, and a minimum particle size of 3.1 μm. Was used, and 6.5% by weight of the carrier was mixed with the carrier. The lubricant was not added to the toner.
[0318]
Table 6 shows the results of these evaluations.
In a combination of a cleaning blade having a JIS-A hardness of 71 degrees and a toner having a large average circularity produced by a polymerization method, the cleaning property of the toner is completely poor, the charging member is contaminated by the toner, and the image quality is uneven. It became many. In addition, the background was lightly soiled.
The toner loss was particularly large when a toner having a minimum particle size of 3.3 μm was used, and when the surface roughness Ry was large, the cleaning failure tended to increase.
[0319]
[Table 6]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0320]
(Examples 23 to 26)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 7 (Example 23); 11 (Example 24); 12 (Example 25); Fourteen samples (Example 26) and an electrophotographic copying machine (IMAZIO MF2200) were prepared. The charging condition used was a charging member-1 for a non-contact charging device, the voltage condition applied to the charging member was an AC voltage of 1500 V / 1350 Hz, and a DC voltage was adjusted to set the surface potential of the photoreceptor. .
The surface potential of the photoconductor at the position of the developing device applied to the photoconductor is no. 7, no. 12 and No. 13 is -600 V; In No. 11, the DC voltage was finely adjusted to −450 V, and 50,000 sheets of paper were run. The developing bias was No. No. 11 is -350V, No. 7, no. 12 and No. 13 was set to -500V. No. The surface potential of No. 11 is low because the film thickness is small. The image portion potential was −60 V to −90 V.
[0321]
A 2 mm-thick cleaning blade [type 2-1] manufactured by adjusting these photoconductors to a JIS-A hardness of 77 degrees is mounted, and the contact pressure against the photoconductor is 23.5 g / cm. It was set in the photoreceptor unit of the electrophotographic copying machine for evaluation. The cleaning blade is automatically grounded by screwing.
[0322]
As the toner, a black toner produced by a polymerization method having an average circularity of 0.993, an average particle size of 5.6 μm, and a minimum particle size of 4.5 μm was used, and 6.5% by weight was mixed with the carrier. The lubricant was not added to the toner.
[0323]
Table 7 shows the results of these evaluations.
Regarding the cleaning property of the toner, both when the photosensitive layer was thin (10.5 μm) and when it was thick (36.8 μm), good results were obtained. The image density was determined by the photoconductor No. 7 was slightly thin, from 1.35 to 1.4, but was 1.5 or more for the other photoconductors, which was good. No. In the case of the photoconductor of No. 13, the characters were crushed due to the thick film thickness, and the resolution was 6.3 to 7.1 (lines / mm). Resolution came out lower.
No. When the image density is low as in No. 7, the toner density can be compensated by increasing the toner density. However, when the image density is too high, there is a possibility that the background will be stained. It is determined that the photosensitive layer thickness of 10 μm is close to the limit. At 30.5 μm, there is still practicality, but if it is more than 30.5 μm, a problem (a decrease in image density and a decrease in resolution due to an increase in residual potential) may occur.
[0324]
[Table 7]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0325]
(Examples 27 to 32)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 15 (Examples 27 and 28); 16 (Examples 29 and 30); 17 (Examples 31 and 32) and 3 samples of the photoreceptor to which an amount of filler of 10 to 40% by weight was added and an electrophotographic copying machine (IMAGEO MF2200) were prepared. Charging member-1 for a non-contact charging device was used for charging, and the voltage conditions applied to the charging member were a DC voltage of -635 V and an AC voltage of 1500 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was all -600 V, and 50,000 sheets of paper were run.
[0326]
These photoconductors are equipped with a cleaning blade [type 1] made of polyurethane rubber having a JIS-A hardness of 81 degrees, and an electrophotographic image for evaluation so that the contact pressure against the photoconductor becomes 22.0 g / cm. It was set in the photoconductor unit of the copying machine.
[0327]
The toner has (1) an average circularity of 0.993, an average particle size of 5.6 μm, a minimum particle size of 4.5 μm, and (2) an average circularity of 0.987, an average particle size of 3.8 μm, and a minimum particle size of 3.3 μm. Was used, and 6.5% by weight of the carrier was mixed with the carrier. As a lubricant for reducing the surface friction coefficient of the photosensitive member, 0.03% by weight of zinc stearate fine powder having an average particle diameter of 0.3 μm was added to the toner.
[0328]
Table 8 shows the evaluation results.
By adding a lubricant to the toner, the surface friction coefficient of the photoreceptor was well controlled between 0.3 and 0.45. As a result, the frictional resistance between the cleaning blade and the photoreceptor was greatly reduced, so that the edge of the cleaning blade was completely distorted, and the toner was sufficiently cleaned even with a toner having a large circularity. As a result, no abnormal image was generated and the resolution was 7.1 lines / mm for the photoconductor (No. 17) with 40% by weight, but the other two lines were 8.0 to 9.0 (lines / mm). mm), which is an extremely good result.
[0329]
[Table 8]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0330]
(Comparative Examples 13 to 16)
The photoconductor was no. No. 14 (filler addition amount 5% by weight); The evaluation was performed under the same conditions as in Examples 15 to 22 except that the cleaning blade was changed to [Type 3] and the cleaning blade was changed to [Type 3]. Table 9 shows the results.
[0331]
No. 5 having a filler content of 5% by weight dispersed. In the photoreceptor of No. 14, since the blade had no reinforcement, the edge portion in contact with the photoreceptor was easily crushed, and the toner sneaked in from the distorted portion. As a result, toner loss occurred, and defective cleaning was confirmed at several places from the beginning.
On the other hand, No. 5 having a filler amount of 50 wt%. In the case of the photoreceptor No. 18, when the toner having the minimum particle size of 3.1 μm was used, the toner loss occurred continuously due to the synergistic effect of the blade without reinforcement and the large surface roughness. In addition, since the amount of addition was large, the image quality was low in resolution (5.6 to 7.1 lines / mm) with low resolution, lots of unevenness, and low resolution.
[0332]
[Table 9]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0333]
(Examples 33 and 34)
As a photoconductor for evaluation, No. 1 shown in Table 1 was used. 6 (Example 33), 8 (Example 34) and an electrophotographic copying machine (Epsio Color 8000, manufactured by Ricoh) were prepared. For charging, a charging member 2-2 for a non-contact charging device was used, and the voltage conditions applied to the charging member were a DC voltage of -695 V and an AC voltage of 1800 V / 1350 Hz.
The DC voltage was finely adjusted so that the surface potential of the photoconductor at the position of the developing device applied to the photoconductor was -680 V, and 50,000 sheets of paper were run. The image portion potential was set to -80 V, and the developing bias was set to -560 V.
[0334]
These photoconductors are equipped with a cleaning blade [type 2-2] made of polyurethane rubber having a JIS-A hardness of 77 degrees, and an electrophotographic image for evaluation so that the contact pressure against the photoconductor becomes 22 g / cm. It was set in the photoconductor unit of the copying machine.
[0335]
Magenta toner (M) having an average circularity of 0.991, an average particle size of 5.1 μm, and a minimum particle size of 3.6 μm, an average circularity of 0.993, an average particle size of 5.1 μm, and a minimum particle size of 0.99 by an emulsion polymerization method. Cyan toner (C) having a diameter of 4.7 μm, average circularity of 0.991, average particle diameter of 5.5 μm, yellow toner (Y) having a minimum particle diameter of 4.2 μm, average circularity of 0.993, and average particle diameter of 5. A black toner (Bk) having a size of 6 μm and a minimum particle size of 4.5 μm was used, and 5% by weight was mixed with the carrier (FPC-300LC). In addition, as a lubricant, 0.03% by weight of zinc stearate powder having a diameter of 0.3 μm was added to the toner.
[0336]
Table 10 shows the evaluation results.
The cleaning member was able to prevent not only toner but also paper dust and the like with a cleaning blade without any problem. Therefore, only scratching of the photoreceptor by the blade did not occur and deep scratching did not occur. For this reason, the image quality was good, and the resolution was as good as 8.0 lines / mm both vertically and horizontally.
[0337]
[Table 10]

(Note) Judgment of ○, △, ×: Judgment from cleaning performance, image quality, wear amount,
○: No problem
Δ: small problem (however, there is a possibility that a problem occurs with 50,000 or more sheets),
×: Practical problem
In the table, μ represents the friction coefficient, and the subscripts 0, 0.1K, and 50K represent the number of sheets passed at the time of evaluation 0 (initial), 100, and 50,000, respectively.
[0338]
【The invention's effect】
According to the configuration of claim 1,
The photoreceptor mounted in the image forming apparatus has a maximum surface roughness maximum peak height Rp and maximum valley depth Rv every time copying is performed. The cleaning failure tends to occur easily when the sum Ry of Rp and Rv becomes larger than the minimum particle size of the toner used. Therefore, by setting Ry> D and making the cleaning blade abut against the counter, it is possible to efficiently suppress toner removal. In addition, the blade used for cleaning has an edge portion in contact with the photoreceptor having a hardness of at least 75 to 90 degrees in JIS-A hardness and a knife-shaped or strip-shaped rubber having a reinforcing plate. The use of the elastic body makes it difficult for the edge in contact with the photoconductor to be twisted or distorted, so that the toner remaining on the photoconductor can be clearly removed. For this reason, only abrasion by the blade occurs on the surface of the photosensitive layer, and toner filming is unlikely to occur, so that abrasion of the photosensitive layer is suppressed.
As a result, deterioration in image quality is reduced, and an image with high resolution and good sharpness can be maintained.
[0339]
2) According to the configuration of claim 2,
By applying and installing a low-resistance substance over the entire length of one side of the upstream blade into which the toner flows, the potential at which the toner flows is set to 0V. This reduces the toner from electrostatically adhering to the wall surface of the cleaning blade and makes it easier for the toner to separate from the cleaning blade, thereby preventing poor cleaning.
[0340]
3) According to the configuration of claim 3,
By setting the minimum particle size of the toner to be charged into the developer to 3 μm, it is possible to suppress toner loss (cleaning is not caused) caused by Ry. In addition, by using a toner having a size of 3 μm or more, health damage due to scattering can be minimized.
[0341]
4) According to the configuration of claims 4 and 5,
Even when a spherical toner having an average circularity of 0.940 to 0.995 is used, development faithful to the image pattern can be performed, so that the resolution and sharpness are improved, and the quality of the second-generation image is improved. Deterioration is also suppressed. The cleaning property can be maintained in an extremely good state, and overall image quality can be greatly improved.
[0342]
5) According to the structure of claim 6,
By setting the total film thickness t of the photosensitive layer to 10 μm ≦ t ≦ 30 μm, it is possible to guarantee the degree of charge required for image formation, and to maintain good resolution and sharpness. The filler-dispersed charge transport layer t ₂ To t ₂ By setting ≦ 8 μm, it is possible to suppress image deterioration due to the residual potential.
[0343]
6) By the structure of claim 7
When the filler is dispersed in the charge transporting layer to form a filler-dispersed charge transporting layer, alumina having an average particle diameter of the added filler of 0.2 μm to 0.7 μm is added to the filler-dispersed charge transporting layer in an amount of 10% by weight or more. By adjusting the content to 40% by weight, the wear resistance is improved, the blade is prevented from biting into the photosensitive layer, and the blade edge is less likely to be distorted and twisted. Further, by suppressing an increase in frictional resistance between the cleaning blade and the photoconductor, distortion and twist of the blade edge are reduced. As a result, defective cleaning of the toner can be improved.
[0344]
7) According to the configuration of claims 8 and 9,
Poor toner cleaning is also caused by the fact that when the frictional resistance between the photoconductor and the cleaning blade is increased, the edge of the cleaning blade is likely to be twisted or distorted, and a slight gap is formed between the photoconductors. This phenomenon can be effectively reduced by lowering the surface friction coefficient of the photoconductor. As means for reducing the amount, a small amount of fine particles of polytetrafluoroethylene or zinc stearate is applied to the photoreceptor, and the friction coefficient (Euler belt Method). By using the low friction coefficient and the blade of the present invention in combination, the cleaning property of the toner is further improved, defective cleaning of the toner is suppressed, and the stable cleaning property can be maintained.
As a result, the durability of the photoreceptor can be increased, and high-resolution, high-sharpness and good image forming properties without image degradation can be maintained. In addition, by reducing the friction coefficient, the blade squeal of the photoconductor can be suppressed.
[0345]
8) According to the configuration of claim 10,
The photoreceptor and cleaning blade of the present invention can be applied to a tandem-type full-color image forming apparatus, and perform good toner cleaning, so that a color with high brightness can be reproduced.
[0346]
9) According to the configuration of claim 11,
In the image forming method using the photoreceptor and the cleaning blade of the present invention, most of the fine particles such as toner are blocked at the entrance of the blade and do not flow out to the charging member, so that the surface of the photoreceptor is only scratched by the blade. Therefore, the occurrence of filming is reduced, and the occurrence of deep scratches such as scratches is also eliminated. Therefore, since the surface of the photosensitive layer is maintained in a clean state, good contrast, high-resolution uniform image formation can be obtained, and the life of the photosensitive member can be extended.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating surface roughness Rp (maximum peak height), Rv (maximum valley depth), and Ry (Rp + Rv).
FIG. 2 is a schematic diagram of an image forming apparatus illustrating a copying process used in the present invention. FIG. 2 shows a diagram in which a cleaning blade made of an elastic body having a sharply cut sharp angle is used, and a vibration damping member is built in the photoconductor.
FIG. 3 is a schematic diagram of an image forming apparatus for explaining a copying process in which a lubricant applying device that applies a lubricant to a surface of a photoreceptor via a brush is installed.
FIG. 4 is a schematic diagram of a quadruple tandem type color laser beam printer using four photoconductors and developing devices for four colors of magenta, cyan, yellow and black.
FIG. 5 shows an example of a process unit. In the figure, the photoconductor, the charging device, the cleaning device, and the transfer device are integrally incorporated.
FIG. 6 is a schematic diagram illustrating the configuration of a basic electrophotographic photosensitive member used in the present invention. An undercoat layer (or an intermediate layer), a charge generation layer, and a charge transport layer (non-filled charge transport layer) are formed in this order.
FIG. 7 is a schematic diagram illustrating a configuration of an electrophotographic photosensitive member used in the present invention. An undercoat layer (or an intermediate layer), a charge generation layer, and a charge transport layer are arranged in this order. Consists of layers.
FIG. 8 shows an example of measuring the surface roughness. A photoreceptor in which 25% by weight of a 0.3 μm alumina filler is added to the filler-dispersed charge transport layer exhibits an initial surface roughness. The sweep width is 2.4 mm.
FIG. 9 shows the surface roughness of the same photoconductor as in FIG. 8 after running 15,000 sheets of paper. It can be seen that the sweep width is 2.4 mm and Rp increases.
FIG. 10 is a diagram illustrating a state in which toner is removed from under a blade and a state in which toner is not removed depending on the size of Ry of a photoconductor.
FIG. 11 is a diagram illustrating a state where spherical toner comes off when a strip-shaped cleaning blade having low hardness is used. It is a graph example which shows the inorganic filler (alpha alumina) average primary particle size dependence of the surface roughness of a filler dispersion | distribution charge transport layer.
FIG. 12 is a view for explaining the shapes of a cleaning blade having a knife-edge shape and a strip-shaped cleaning blade reinforced with a metal plate.
FIG. 13 is a view for explaining the shapes of a cleaning blade having a knife-edge shape and a strip-shaped cleaning blade reinforced with a metal plate.
FIG. 14 is a diagram showing dimensions and angles of a cleaning blade having a knife-edge shape and a strip-shaped cleaning blade reinforced with a metal plate.
FIG. 15 is a diagram showing dimensions and angles of a cleaning blade having a knife-edge shape and a strip-shaped cleaning blade reinforced with a metal plate.
FIG. 16 is an explanatory diagram showing a contact angle of a cleaning blade.
FIG. 17 is an explanatory diagram illustrating a contact angle of a cleaning blade.
FIG. 18 is a schematic diagram illustrating a situation in which burrs on a contact surface of a cleaning blade manufactured by die molding with a photoconductor are cut.
FIG. 19 is a schematic diagram illustrating a state of toner cleaning by the cleaning blade (knife edge shape) of the present invention.
[Explanation of symbols]
1: Photoreceptor for electrophotography (photoreceptor)
2: Charging device
3: Image exposure device
4: Developing device
5: transfer device
6: Separation device
7: Cleaning device
7-1: Cleaning blade
8: Fixing device
9: Copy paper
200: Lubricant application device
201: Lubricant
202: Brush with lubricant

Claims (11)

An electric charge is applied to the electrophotographic photosensitive member by a charging device, an electrostatic latent image is formed by optical writing, the electrostatic latent image is visualized with toner, the toner is transferred to a transfer-receiving member, and the photosensitive member is cleaned. In an image forming apparatus using an indirect electrophotographic method of cleaning with a blade,
When the maximum valley depth of the surface roughness of the electrophotographic photosensitive member is Rv, the maximum ridge height is Rp, and the minimum particle size of the toner is D, the sum Ry of the maximum valley depth Rv and the maximum ridge height Rp and The minimum particle diameter D of the toner is Ry <D,
The cleaning blade is held so as to abut against the electrophotographic photosensitive member in the counter direction, and the cleaning blade has a knife-shaped or strip-shaped edge portion in contact with the electrophotographic photosensitive member, and has one surface in the longitudinal direction. An image forming apparatus comprising a rubber-like elastic body having a JIS-A hardness of 75 to 90 degrees reinforced with a metal plate. 2. The image according to claim 1, wherein the cleaning blade is subjected to a conductive treatment with a low-resistance substance over the entire length of one surface on the upstream side where the toner flows in the longitudinal direction, and is grounded. Forming equipment. The image forming apparatus according to claim 1, wherein the minimum particle diameter D of the toner is 3 μm or more. The image forming apparatus according to claim 1, wherein the toner is a spherical toner. The image forming apparatus according to claim 4, wherein the spherical toner has an average circularity of 0.940 to 0.995. The electrophotographic photosensitive member is an organic photosensitive member in which a charge transport layer is formed at a position farthest from the conductive support, and the charge transport layer has a single-layer structure in which no filler is added, or has a charge transport layer. layer filler undispersed charge transport layer t ₁ having no clear interface to two layers, a laminated structure of a filler dispersed charge transport layer t _2, for the 10 [mu] m ≦ t ≦ 30 [mu] m film thickness of the charge transport layer and t , and the thickness of the relationship between the filler undispersed charge transport layer t thickness of ₁ and the filler dispersed charge transport layer t ₂ is t ₁ ≧ t _2, and the thickness of the filler dispersed charge transport layer t ₂ 6. The image forming apparatus according to claim 1, wherein t ₂ ≦ 8 μm. 7. The image forming apparatus according to claim 6, wherein 10 to 40% by weight of alumina having an average particle size of 0.2 [mu] m to 0.7 [mu] m is dispersed in the filler-dispersed charge transport layer. A method of coating the surface of the electrophotographic photoreceptor with a lubricant such as polytetrafluoroethylene or zinc stearate on the surface of the photoreceptor to reduce the surface friction coefficient of the electrophotographic photoreceptor. The image forming apparatus according to any one of claims 1 to 7. 9. The image forming apparatus according to claim 1, wherein a surface friction coefficient of the electrophotographic photosensitive member is 0.3 to 0.45 as measured by an Euler belt method. At least a tandem type color system in which a charging device, magenta, or a developing device made of cyan, yellow, or black toner, an image exposing device, and a cleaning device are respectively arranged in four systems centering on the electrophotographic photosensitive member. The image forming apparatus according to claim 1, wherein: An image forming method capable of forming an image in an image forming apparatus using the cleaning blade, the toner, and the electrophotographic photosensitive member according to claim 1.

Images