JP4254324B2 - Image forming apparatus and image forming method - Google Patents

Description

【０１７５】
【表２】

【０１７６】
〔現像剤の製造〕
トナー１Ｂｋ〜１Ｃ、トナー２Ｂｋ〜２Ｃ、トナー３Ｂｋ〜３Ｃ、トナー４Ｂｋ〜４Ｃ、トナー５Ｂｋ〜５Ｃ、トナー６Ｂｋ〜６Ｃｃの各トナー１０質量部と、スチレン−メタクリレート共重合体で被覆した４５μｍフェライトキャリア１００質量部とを混合することにより、評価用の現像剤１Ｂｋ〜１Ｃ、現像剤２Ｂｋ〜２Ｃ、現像剤３Ｂｋ〜３Ｃ、現像剤４Ｂｋ〜４Ｃ、現像剤５Ｂｋ〜５Ｃ、現像剤６Ｂｋ〜６Ｃｃを製造した。
〔感光体の作製〕
下記のごとくして、実施例に用いる感光体を作製した（各実施例の感光体は各画像ユニット共、同じ種類の感光体を用いる為、計４本以上を作製した）。
【０１７７】
感光体１の作製
下記中間層塗布液を調製し、洗浄済み円筒状アルミニウム基体上に浸漬塗布法で塗布し、乾燥膜厚０．３μｍの中間層を形成した。
【０１７８】
〈中間層（ＵＣＬ）塗布液〉
ポリアミド樹脂（アミランＣＭ−８０００：東レ社製） ６０ｇ
メタノール １６００ｍｌ
下記塗布液成分を混合し、サンドミルを用いて１０時間分散し、電荷発生層塗布液を調製した。この塗布液を浸漬塗布法で塗布し、前記中間層の上に乾燥膜厚０．２μｍの電荷発生層を形成した。
【０１７９】
〈電荷発生層（ＣＧＬ）塗布液〉
Ｙ型チタニルフタロシアニン（Ｃｕ−Ｋα特性Ｘ線によるＸ線回折の
最大ピーク角度が２θで２７．３） ６０ｇ
シリコーン樹脂溶液（ＫＲ５２４０、１５％キシレン−ブタノール溶液
：信越化学社製） ７００ｇ
２−ブタノン ２０００ｍｌ
下記塗布液成分を混合し、溶解して電荷輸送層塗布液を調製した。この塗布液を前記電荷発生層の上に浸漬塗布法で塗布し、膜厚２０μｍの電荷輸送層を形成した。
【０１８０】
〈電荷輸送層（ＣＴＬ）塗布液〉
電荷輸送物質（４−メトキシ−４′−（４−メチル−α−フェニルスチリル）
トリフェニルアミン） ２００ｇ
ビスフェノールＺ型ポリカーボネート
（ユーピロンＺ３００：三菱ガス化学社製） ３００ｇ
ヒンダードアミン（サノールＬＳ２６２６：三共社製） ３ｇ
疎水性シリカ（数平均一次粒径：２０ｎｍ） ３０ｇ
１，２−ジクロロエタン ２０００ｍｌ
上記感光体１の表面の水に対する接触角は８４°であった。
【０１８１】
感光体２の作製
感光体１の作製において、電荷輸送層までは同様に塗布した。
【０１８２】
〈表面保護層〉
電荷輸送物質（４−メトキシ−４′−（４−メチル−α−フェニルスチリル）
トリフェニルアミン） ２００ｇ
ビスフェノールＺ型ポリカーボネート
（ユーピロンＺ３００：三菱ガス化学社製） ３００ｇ
ヒンダードアミン（サノールＬＳ２６２６：三共社製） ３ｇ
疎水性シリカ（数平均一次粒径：２０ｎｍ） ８ｇ
ポリテトラフルオロエチレン樹脂粒子（平均粒径０．５μｍ） １００ｇ
１−ブタノール ５０ｇ
を混合し、溶解して表面保護層塗布液を調製した。この塗布液を前記電荷輸送層の上に浸漬塗布法で塗布し、１００℃、４０分の加熱硬化を行い乾燥膜厚４μｍの表面保護層を形成し、感光体２を作製した。該感光体２の表面の水に対する接触角は１１２°であった。
【０１８３】
感光体３〜６の作製
上記感光体２の表面保護層中のポリテトラフルオロエチレン樹脂粒子（平均粒径０．５μｍ）の量を増減して、前記表面接触角を１２４°、１１８°、９６°、９１°に変化させた感光体３、４、５、６を作製した。
【０１８４】
表面エネルギー低下剤Ａ〜Ｆの作製
ステアリン酸ナトリウムを水に溶解し、１５質量％液を作製した。又、硫酸亜鉛を水に溶解し、２５質量％液を作製した。直径６ｃｍのタービン羽根を有する撹拌装置付きの２リットルの受け容器を用意し、タービン羽根を３５０ｒｐｍで回転させた。この受け容器にステアリン酸ナトリウム液を投入し、液温８０℃に調整した。次に、この受け容器に８０℃にした硫酸亜鉛液を３０分かけて滴下した。ステアリン酸ナトリウムと硫酸亜鉛の当量比は０．９８とし、金属石鹸スラリー量が５００ｇとなるように混合した。全量仕込み終了後、反応時の温度状態で、１０分間熟成し、反応を終結させた。次にこのようにして得られた金属石鹸スラリーを２回水洗し、続いて水を用いて洗浄した。得られた金属石鹸ケーキを１１０℃の乾燥温度で乾燥し、１５ＭＰａの圧力で固形化した。その後３０℃８０％ＲＨの環境条件下に２４時間放置し、表３に示す含水率を変化させたステアリン酸亜鉛の固形材料（表面エネルギー低下剤Ａ〜Ｆ）を得た。これらＡ〜Ｆの含水率は１１０℃の乾燥時間を変化させて調製した。
【０１８５】
【表３】

【０１８６】
実施例１
〈評価〉
各実施例、比較例において、表２に示す組み合わせの感光体及び現像剤群（トナー群）を用い、Ｙ（イエロー）、Ｍ（マゼンタ）、Ｃ（シアン）、Ｂｋ（ブラック）の各現像手段を有する画像形成ユニットを図１記載の中間転写体を有するデジタル複写機に搭載し、オリジナル画像に白地部、Ｂｋ及びＹ、Ｍ、Ｃのソリッド（べた）画像部、文字画像部、ハーフトーン画像を有するＡ４画像を常温常湿（２０℃、５０％ＲＨ）下、１万枚印刷し評価した。評価項目、評価方法、評価基準を下記に記載する。
【０１８７】
文字チリ
文字画像を形成し、目視及び２０倍ルーペにて文字周辺のトナーチリを観察し、以下の基準で評価した。
【０１８８】
◎：ルーペ観察でも、文字周辺のトナーチリが観察されない（良好）
○：目視では判別できないが、ルーペでは文字周辺のトナーチリが観察される（実用上問題ない）
×：目視で文字周辺のトナーチリが観察され、文字の鮮鋭性が劣る（実用上 問題あり）
転写抜け
濃度０．４のハーフトーン画像を転写紙（坪量２００ｇ／ｍ²）の両面に形成し、転写抜けによるホワイトスポットの発生を目視にて評価した。
【０１８９】
◎◎：まったく転写抜けない（非常に良好）
◎：画像１００枚あたり裏面のみ１〜２個の転写抜けが存在するものの凝視しなければ判別できない（良好）
○：画像５０枚あたり１〜４個の転写抜けが存在するものの凝視しなければ判別できない（実用上問題ない）
×：画像５０枚あたり、表裏関係なく、５個以上の明瞭な転写抜けが存在する（実用上問題あり）
ブラックスポット
ハーフトーン画像に、周期性が感光体の周期と一致し、ブラックスポット（苺状のスポット画像）がＡ４サイズ当たり何個あるかで判定した。
【０１９０】
◎：０．４ｍｍ以上のブラックスポットの発生頻度：全ての複写画像が３個／Ａ４以下（良好）
○：０．４ｍｍ以上のブラックスポットの発生頻度：４個／Ａ４以上、１５個／Ａ４以下が１枚以上発生（実用上問題なし）
×：０．４ｍｍ以上のブラックスポットの発生頻度：１６個／Ａ４以上が１枚以上発生（実用上問題有り）
画像濃度
画像濃度の測定は、各色のべた部を濃度計「ＲＤ−９１８」（マクベス社製）を使用し、記録紙をゼロとした相対反射濃度で測定した。
【０１９１】
◎：Ｂｋ、及びＹ、Ｍ、Ｃのソリッド（べた）画像部の各濃度が１．２以上（良好）
○：Ｂｋ、及びＹ、Ｍ、Ｃのソリッド（べた）画像部の各濃度が０．８以上（実用上問題なし）
×：Ｂｋ、及びＹ、Ｍ、Ｃのソリッド（べた）画像部の各濃度が０．８未満（実用上問題あり）
（鮮鋭性）
画像の鮮鋭性は、低温低湿（１０℃２０％ＲＨ）、高温高湿（３０℃８０％ＲＨ）の両環境において画像を出し、文字潰れで評価した。３ポイント、５ポイントの文字画像を形成し、下記の判断基準で評価した。
【０１９２】
◎：３ポイント、５ポイントとも明瞭であり、容易に判読可能
○：３ポイントは一部判読不能、５ポイントは明瞭であり、容易に判読可能
×：３ポイントは殆ど判読不能、５ポイントも一部あるいは全部が判読不能
中間転写体を有するデジタル複写機のプロセス条件
画像形成のライン速度Ｌ／Ｓ：１８０ｍｍ／ｓ
感光体（６０ｍｍφ）の帯電条件：非画像部の電位は、電位センサで検知し、フィードバック制御できるようにし、その制御可能範囲は−５００Ｖ〜−９００Ｖであり、全露光した場合の感光体の表面電位は−５０〜０Ｖの範囲にした。
【０１９３】
像露光光：半導体レーザ（波長：７８０ｎｍ）
中間転写体：シームレスの無端ベルト状中間転写体７０を用い、半導電樹脂製のベルトで体積抵抗率が１×１０⁸Ω・ｃｍ、Ｒｚが０．９μｍのものを用いた。
【０１９４】
一次転写条件
一次転写ローラ（図１の５Ｙ、５Ｍ、５Ｃ、５Ｂｋ（各６．０５ｍｍφ））：芯金に弾性ゴムを付した構成：表面比抵抗１×１０⁶Ω、転写電圧印加
二次転写条件
中間転写体としての無端ベルト状中間転写体７０とそれを挟み込むようにバックアップローラ７４と二次転写ローラ５Ａが配置され、バックアップローラ７４の抵抗値が１×１０⁶Ωであり、二次転写手段としての二次転写ローラの抵抗値が１×１０⁶Ωであり定電流制御（約８０μＡ）をするようにしてある。
【０１９５】
定着はローラ内部にヒータを配置した定着ローラによる熱定着方式である。
中間転写体と感光体との最初の接触点から次色感光体との最初の接触点までの中間転写体上での距離Ｙは９５ｍｍにした。
【０１９６】
駆動ローラ７１、ガイドローラ７２、７３及び二次転写のためのバックアップローラ７４の外周長さ（円周長さ）を３１．６７ｍｍ（＝９５ｍｍ／３）にし、テンションローラ７６の外周長さを２３．７５ｍｍ（＝９５ｍｍ／４）にした。
【０１９７】
そして、一次転写ローラの外周長さを１９ｍｍ（＝９５ｍｍ／５）にした。
感光体のクリーニング条件
クリーニングブレード：ウレタンゴムブレードを感光体回転方向にカウンター方式で当接した。
【０１９８】
中間転写体のクリーニング条件
クリーニングブレード：ウレタンゴムブレードを中間転写体進行方向にカウンター方式で当接した。
【０１９９】
結果を表４に示す。
【０２００】
【表４】

【０２０１】
上記表４より、本発明の要件を満足する感光体（表面の水に対する接触角が９０°以上）と現像手段の現像剤群の組み合わせ、即ち、各色トナーの濁度が６０未満で、各色トナー間の濁度の差が最大１０〜３５の範囲にある現像剤群の組み合わせ（Ｎｏ．４〜８、１０〜１１、１４〜１９、２２、２３、２５、２６、２８、２９）は文字チリ、転写抜け、ブラックスポット、画像濃度、鮮鋭性とも実用範囲以上の良好な評価を達成しているのに対し、本発明外の現像剤群を用いた組み合わせ（Ｎｏ．１、９、１３、２１、２４、２７、３０）では、各色トナー間の濁度の差が４．１のＮｏ．１ではトナーの流動性が十分でなく、転写抜け、画像濃度、鮮鋭性が低下し、濁度差が４７台のＮｏ．１３、Ｎｏ．３０では帯電量のバランスの不安定さから、文字チリ（カラーの文字チリ）が多く、鮮鋭性が低下している。Ｎｏ．３０では、転写抜けも発生している。又、各色トナーのいずれかの濁度が６０以上の現像剤群（Ｎｏ．２１、Ｎｏ．２４、Ｎｏ．２７）は遊離外添剤が過多となり、ブラックスポットが多発して鮮鋭性が低下している。又、表面の水に対する接触角が８４°の感光体を用いた組み合わせ（Ｎｏ．９）では、転写抜けが発生し、鮮鋭性が劣化している。又、本発明の要件を満たす組み合わせの中でも、表面の水に対する接触角が９５°以上の感光体と前記現像剤群の各色トナー間の濁度の差が最大１０〜３５で且つ黒トナーの濁度が２０未満の現像剤群（Ｎｏ．４、５、６、７、１０、１１、１４、１５、１６、１８、２９）は改善効果が顕著である。
【０２０２】
実施例２（感光体１を用い、表面エネルギー低下剤を供給した例）
上記実施例１の中間転写体を有するデジタル複写機の画像形成装置ユニットのクリーニング装置を図５に示した剤付与手段を兼ねたブラシロールを持つクリーニング手段に変更し、表面エネルギー低下剤のステアリン酸亜鉛を図５の６６Ｋに設置して、感光体表面にブラシロールを介してステアリン酸亜鉛を供給しながら、実施例１と同様に表５に示す感光体、表面エネルギー低下剤及び現像剤群（トナー群）を組み合わせた（組み合わせＮｏ．３１〜６０）画像形成ユニットを中間転写体を有するデジタル複写機組み込み評価した。評価項目、評価方法、評価基準も実施例１と同様にした。
【０２０３】
図５の剤付与手段を有するクリーニング手段のクリーニング条件
クリーニングブレード：ウレタンゴムブレードを感光体回転方向にカウンター方式で当接した。
【０２０４】
クリーニングブラシ：導電性アクリル樹脂、ブラシ毛密度（３×１０³／ｃｍ²）、食い込み量を１．０ｍｍに設定した。
【０２０５】
【表５】

【０２０６】
上記の条件での評価をした。その結果、実施例１とほぼ同一の評価結果が得られた。即ち、感光体の表面層がフッ素系樹脂粒子を含有していなくても、感光体表面に表面エネルギー低下剤を供給し、感光体表面の水に対する接触角を９０°以上にすることにより、実施例１と同様の効果が得られた。
【０２０７】
実施例３（トナーの粒度分布を変更した例）
（トナー７Ｂｋ、７Ｙ、７Ｍ、７Ｃの作製）
前記トナー２Ｂｋ、２Ｙｂ、２Ｍ、２Ｃのトナー製造において、遠心沈降法による液中の分級のレベルを変えて、Ｍ（ｍ₁＋ｍ₂）等を変えた以外は、同様にしてトナー７Ｂｋ、７Ｙ、７Ｍ、７Ｃを作製した。トナー７Ｂｋ、７Ｙ、７Ｍ、７Ｃのトナーの個数平均粒径、Ｍ（ｍ₁＋ｍ₂）及びトナー濁度を表６に示す。
【０２０８】
これらのトナーの各トナー１０質量部と、スチレン−メタクリレート共重合体で被覆した４５μｍフェライトキャリア１００質量部とを混合することにより、評価用の現像剤７Ｂｋ、７Ｙ、７Ｍ、７Ｃとした現像剤２２群を作製した。
（トナー８Ｂｋ、８Ｙ、８Ｍ、８Ｃの作製）
前記トナー２Ｂｋ、２Ｙｂ、２Ｍ、２Ｃのトナー製造において、遠心沈降法による液中の分級のレベルを変えて、Ｍ（ｍ₁＋ｍ₂）等を変えた以外は、同様にしてトナー８Ｂｋ、８Ｙ、８Ｍ、８Ｃを作製した。トナー８Ｂｋ、８Ｙ、８Ｍ、８Ｃのトナーの個数平均粒径、Ｍ（ｍ₁＋ｍ₂）及びトナー濁度を表６に示す。
【０２０９】
これらのトナーの各トナー１０質量部と、スチレン−メタクリレート共重合体で被覆した４５μｍフェライトキャリア１００質量部とを混合することにより、評価用の現像剤８Ｂｋ、８Ｙ、８Ｍ、８Ｃとした現像剤２３群を作製した。
【０２１０】
【表６】

【０２１１】
実施例１の組み合わせＮｏ．４の現像剤４群（トナー２Ｂｋ、２Ｙｂ、２Ｍ、２Ｃ）の代わりに現像剤２２群、２３群を用いた他は、実施例１と同様にして評価を行った。その結果を表７に示す。
【０２１２】
【表７】

【０２１３】
表７より、前記トナー粒子の相対度数の和（Ｍ）が７０％以上の現像剤２２群は、（Ｍ）が７０％未満の現像剤２３群に比し、評価項目の改善度が優れていることが見られる。
【０２１４】
【発明の効果】
本発明を用いることにより、中間転写体を用いた電子写真方式のトナー転写特性の改善を達成でき、トナー転写の低下から発生する転写抜けや文字チリ等の画像欠陥を防止でき、且つ画像濃度や鮮鋭性が良好なカラー画像を形成できる電子写真方式の画像形成装置、画像形成方法を提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態を示すカラー画像形成装置の断面構成図である。
【図２】中間転写体のクリーニング手段の一例である。
【図３】感光体と無端ベルト状中間転写体と一次転写ローラとの位置関係を示す配置図である。
【図４】バックアップローラと無端ベルト状中間転写体と二次転写ローラとの位置関係を示す配置図である。
【図５】本発明の画像形成ユニットに設置されるクリーニング手段の構成図である。
【符号の説明】
１Ｙ、１Ｍ、１Ｃ、１Ｂｋ 感光体
２Ｙ、２Ｍ、２Ｃ、２Ｂｋ 帯電手段
３Ｙ、３Ｍ、３Ｃ、３Ｂｋ 露光手段
４Ｙ、４Ｍ、４Ｃ、４Ｂｋ 現像手段
５Ａ 二次転写ローラ（二次転写手段）
５Ｙ、５Ｍ、５Ｃ、５Ｂｋ 一次転写ローラ（一次転写手段）
６Ａ、６Ｙ、６Ｍ、６Ｃ、６Ｂｋ クリーニング手段
７ 無端ベルト状中間転写体ユニット
１０Ｙ、１０Ｍ、１０Ｃ、１０Ｂｋ 画像形成部（画像形成ユニット）
６１ ブレード
６２ ブラケット
６３ 支軸
７０ 無端ベルト状中間転写体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus used as a color copying machine or a color printer, and an image forming method using the image forming apparatus.
[0002]
[Prior art]
In recent years, color copying machines and color printers have a strong tendency to obtain color images. Color image forming methods with high practical value can be broadly classified by commonly used names. Multi-color overlay on transfer drum method, intermediate transfer method, KNC method (electrophotographic photosensitive member (hereinafter also referred to simply as photosensitive member)). There are four types: tandem method, which makes a combined image and batch transfer).
[0003]
Of course, since these are names given from different viewpoints, there are naturally, for example, an intermediate transfer system and a tandem system. This tandem color image forming apparatus is known for obtaining a high-quality full-color image. In this method, a toner image is formed on each photoconductor corresponding to each color of yellow, magenta, cyan, and black, a color superposition image is formed on an intermediate transfer body, and is collectively transferred onto a transfer material.
[0004]
In this tandem color image formation, there are often two stages of transfer processes, a primary transfer in which a toner image is transferred from each photoconductor to an intermediate transfer body and a secondary transfer in which the toner image is transferred from the intermediate transfer body to a recording paper. Image defects due to image transfer defects are likely to occur.
[0005]
For example, defective transfer of toner from the photosensitive member to the intermediate transfer member tends to cause image defects such as a decrease in image density and missing transfer. On the other hand, poor transfer of toner from the intermediate transfer member to recording paper has been reported such as character dust and sharpness reduction accompanying transfer repelling, and periodic image defects accompanying toner filming on the intermediate transfer member.
[0006]
In order to improve transferability, prevent toner filming, or improve cleaning defects that cause this “transfer omission” and “character dust”, the surface layer of the electrophotographic photosensitive member is incorporated with fine particles on the surface. Techniques have been studied such as providing irregularities, reducing the adhesion of toner on the surface of the photoreceptor, improving transferability, and reducing the frictional force with the blade. For example, it has been reported that alkylsilsesquioxane resin fine particles are contained in a photosensitive layer (Patent Document 1). However, the alkylsilsesquioxane resin fine particles have a hygroscopic property, and in a high-humidity environment, there arises a problem that the wettability of the surface of the photoreceptor, that is, the surface energy increases, and the transferability tends to decrease. On the other hand, in order to reduce the surface energy of the photoreceptor, an electrophotographic photoreceptor containing a fluororesin powder has been reported. However, the fluororesin powder has a problem that sufficient surface strength cannot be obtained, streak failure due to scratches on the surface of the photoreceptor is likely to occur, and image blurring is likely to occur (Patent Document 2).
[0007]
On the other hand, in order to improve the transferability of the intermediate transfer member, a technique for supplying a solid lubricant to the intermediate transfer member to reduce the surface energy of the intermediate transfer member is disclosed (Patent Documents 3, 4, and 5). ). However, simply controlling the surface of such an intermediate transfer body is still insufficient for improving the total transferability of an image forming system using an intermediate transfer body having two transfer steps, particularly at high temperatures. It has been found that further improvement is necessary for the formation of high humidity and long-term copy images.
[0008]
On the other hand, looking at the electrophotographic process, the latent image forming method is roughly divided into analog image forming using a halogen lamp as a light source and digital image forming using an LED or a laser as a light source. Recently, a digital latent image forming method is rapidly becoming mainstream as a printer of a personal computer and also in an ordinary copying machine because of the ease of image processing and the development to a multifunction machine.
[0009]
In digital image formation, not only copying but also the use of producing original images increases, and digital electrophotographic image formation tends to require higher image quality.
[0010]
In response to the demand for higher image quality, research is underway to faithfully visualize the latent image on the electrophotographic photosensitive member using a toner having a reduced particle size with controlled shape factor and particle size distribution. Even when such a toner is applied to the image forming system using the intermediate transfer member, the effect of improving the transferability of the toner and the improvement of the cleaning property are not as high as originally expected. Is likely to occur.
[0011]
That is, in the image forming method using the intermediate transfer member, the balance between the surface energy of both the electrophotographic photosensitive member and the intermediate transfer member is adjusted, and the toner characteristics are improved to the intermediate transfer method. It has been found that it is necessary to improve the transferability of both the total toner.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-181291
[0013]
[Patent Document 2]
JP-A 63-56658
[0014]
[Patent Document 3]
JP-A-6-337598
[0015]
[Patent Document 4]
JP-A-6-332324
[0016]
[Patent Document 5]
JP 7-271142 A
[0017]
[Problems to be solved by the invention]
The present invention has been made to solve the above problems. An object of the present invention is to provide an electrophotographic image of good color using an image forming apparatus using an intermediate transfer member, particularly in color images using an intermediate transfer member in the formation of a large number of images. It is an object of the present invention to provide an image forming apparatus and an image forming method of an electrophotographic system that improve color omission, character dust, and sharpness degradation, and reproduce a color image with good sharpness and a vivid hue.
[0018]
[Means for Solving the Problems]
In the image forming apparatus for forming a color image using the intermediate transfer member of the present invention, the primary transferability of the color toner image from the photosensitive member to the intermediate transfer member, and the recording material for each color toner image superimposed on the intermediate transfer member As a result of detailed examination of the secondary transfer property to the toner, the amount of the free external additive of each color toner is greatly related to the primary transfer property and the secondary transfer property, particularly the secondary transfer property from the intermediate transfer member to the recording paper. The present invention was completed. That is, by using a toner having a large amount of free external additive and a large turbidity for at least one of the color toners, the transferability of the toner from the intermediate transfer member to the recording paper is remarkably improved, and transfer omission In addition, it is possible to form a color electrophotographic image with few sharpness and image defects such as character dust and good sharpness.
[0019]
That is, the object of the present invention is achieved by adopting one of the following configurations. 1. A plurality of image forming units having an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are provided, and the electrophotographic photosensitive member is formed using toner having a different hue for each of the plurality of image forming units. A primary transfer means for forming a toner image thereon, sequentially transferring the formed toner image from the electrophotographic photosensitive member to the intermediate transfer member, and forming a color toner image on the intermediate transfer member; and Image forming apparatus having secondary transfer means for transferring color toner image on intermediate transfer member to recording material Forming method using The amount of external additive added to each color toner used in the developing means of the plurality of image forming units is constant, and the turbidity of each color toner defined below is less than 60, Among each color toner, the toner with the maximum turbidity is a yellow toner, An image forming apparatus having a maximum turbidity difference of 10 to 35 for each color toner and a contact angle of 90 ° or more with water on the surface of the electrophotographic photosensitive member. Toner turbidity: HAZE value = defined as a percentage of diffuse component / total transmitted component. Method for measuring turbidity of toner: 5.0 g of toner is dispersed in 50 ml of an aqueous solution containing 1 ml of a surfactant (detergency family; manufactured by Kao Corporation) and separated using a centrifuge (2000 rpm: 10 minutes). . Since the toner component precipitates, a supernatant liquid which is a free component is collected. Using this, COH-300A manufactured by Nippon Denshoku Co., Ltd., the HAZE value (percentage: where% is omitted) calculated from the ratio of the diffuse component of the total transmitted component to the incident light is used as the turbidity of the toner. .
[0020]
2. 2. The image formation as described in 1 above, wherein the surface layer of at least one electrophotographic photosensitive member of the plurality of image forming units contains fluororesin particles. Method .
[0021]
3. 2. The image forming apparatus as described in 1 above, wherein at least one of the plurality of image forming units has an agent applying means for supplying a surface energy reducing agent to the surface of the electrophotographic photosensitive member. Method .
[0022]
4). When the particle size distribution of each color toner used for the developing means of the plurality of image forming units is D (μm), the natural logarithm lnD is taken on the horizontal axis, and a plurality of the horizontal axes are arranged at intervals of 0.23. In the histogram showing the number-based particle size distribution divided into classes, the relative frequency of the toner particles included in the most frequent class (m ₁ ) And the relative frequency (m of toner particles contained in the next most frequent class after the most frequent class) ₂ 4) The image formation as described in any one of 1 to 3 above, wherein a sum (M) with respect to (1) is 70% or more. Method .
[0024]
5. A plurality of image forming units are four image forming units, an image forming unit having black toner, an image forming unit having yellow toner, an image forming unit having magenta toner, and an image forming having cyan toner 5. The image formation according to any one of 1 to 4 above, comprising a unit. Method .
[0025]
6). The image formation as described in any one of 1 to 5 above, wherein the black toner has a toner turbidity of less than 20. Method .
[0027]
Hereinafter, the present invention will be described in more detail.
In the present invention, the turbidity of the toner is defined as follows and can be measured.
[0028]
Turbidity; HAZE value = defined as a percentage of diffuse component / total transmitted component.
Method for measuring turbidity of toner: 5.0 g of toner is dispersed in 50 ml of an aqueous solution containing 1 ml of a surfactant (detergency family; manufactured by Kao Corporation) and separated using a centrifuge (2000 rpm: 10 minutes). . Since the toner component precipitates, a supernatant liquid which is a free component is collected. Using this, COH-300A manufactured by Nippon Denshoku Co., Ltd., the HAZE value (percentage: where% is omitted) calculated from the ratio of the diffuse component of the total transmitted component to the incident light is used as the turbidity of the toner. .
[0029]
When the turbidity value of the toner is large, it means that there are many free components of fine particles such as external additives.
[0030]
In the present invention, the turbidity of each color toner used in the developing means of a plurality of image forming units is less than 60, and the difference in turbidity between the color toners is maximum. 10-3 By using the toner group No. 5, the transferability of the color toner image superimposed on the intermediate transfer member to the recording paper is remarkably improved, and transfer defects, character dust, toner filming on the intermediate transfer member, etc. A periodic image defect can be remarkably improved, and a color image with excellent sharpness and a vivid hue can be formed.
[0031]
That is, when the turbidity of each color toner is 60 or more, since there are many free components of fine particles, the free components are scattered on the photosensitive member and the intermediate transfer member, and character dust and sharpness are liable to occur. In addition, a large amount of free components adhere to the surface of the photoreceptor, and image defects such as black spots (spotted spot images) tend to occur. Further, even if the turbidity of each color toner is less than 60, if the difference in turbidity between each color toner is less than 5 at the maximum, the transferability of the toner from the photoconductor to the intermediate transfer member is reduced and the transfer from the intermediate transfer member to the recording paper is performed. It is easy to cause deterioration in transferability, loss of transfer, reduction in color image density, reduction in sharpness, and the like. On the other hand, if the difference in turbidity between the toners of each color is greater than 45 at the maximum, it is difficult to control the balance of the charge amount between the toners, character dust is likely to occur, and sharpness is likely to deteriorate.
[0032]
The turbidity of each color toner is less than 60, preferably less than 50, most preferably less than 40. On the other hand, the difference in turbidity between each color toner is the greatest. 1 large 0-35.
[0033]
As each color toner of the present invention, it is preferable to use a toner group of four colors of black toner, yellow toner, magenta toner, and cyan toner. By using four color toners, both the character image and the color image can be produced clearly and vividly.
[0034]
Of the toners of the respective colors, the turbidity of the black toner is preferably less than 20. When the turbidity of the black toner is less than 20, the sharpness of the image mainly composed of characters is easily formed.
[0035]
Of the color images, the toner having the maximum turbidity is preferably a yellow toner. Even when the turbidity of the yellow toner is increased, the sharpness and the hue are hardly lowered.
[0036]
In order to control the turbidity of the toner within a range of less than 60 according to the above definition and the measurement method and to make the turbidity difference between the toners 5 to 45 at the maximum, the external additive particles adhering to the toner surface It is important to select the type and control the degree of fixation of the external additive particles (hereinafter also simply referred to as external additive) to the toner surface.
[0037]
The number average particle diameter of the external additive preferably used in the present invention is 0.05 to 0.5 μm.
[0038]
When the particle size of the external additive is smaller than 0.05 μm, the physical adhesive force between the toner photoreceptors is not reduced, so that the transferability is lowered, and as a result, the image density is lowered.
[0039]
When the particle size is larger than 0.5 μm, the external additive once adhered is easily separated and released by stress such as agitation in the developing device, and the released amount is accumulated in the developing device. Reaggregates and becomes a nucleus at the time of transfer, resulting in transfer omission. In addition, since many free components adhere to the surface of the photoconductor, filming on the surface of the photoconductor tends to occur.
[0040]
The amount of the external additive added to the toner is 0.05 to 5.0 parts by mass (hereinafter referred to as “parts” unless otherwise specified) with respect to 100 parts by mass of the colored particles (toner before addition of the external additive) “Parts by mass” is preferred, and 1.0 to 4.0 parts is particularly preferred.
[0041]
If the amount is less than 0.05 parts, the effect of reducing the physical adhesive force cannot be obtained, and the transferability is likely to be lowered. When the amount is more than 5.0 parts, an excessive external additive is present on the toner surface, so that it tends to be easily detached and released by stress such as stirring in the developing device. For this reason, the liberated material is accumulated in the developing device and re-aggregates in the developing device to become nuclei. When this is mixed into the developed toner image, transfer omission is likely to occur during transfer. Further, since a large amount of free components adhere to the surface of the photoreceptor, toner filming on the surface of the photoreceptor is likely to occur.
[0042]
The method for controlling the adhesion state of the external additive to the colored particles is not limited, and any of the commonly used fine particle external addition devices and devices that fix or adhere to the toner surface can be used.
[0043]
As a specific apparatus for immobilization, a Henschel mixer, a Roedige mixer, a TURBO SPHERE mixer, or the like can be used. Among them, the Henschel mixer can be suitably used from the viewpoints of being able to perform mixing and fixing of the external additive with the same apparatus, ease of stirring and mixing, and ease of heating from the outside.
[0044]
As a mixing method at the time of the fixing process, it is desirable that the peripheral speed at the tip of the stirring blade is 5 to 50 m / s. The treatment is preferably performed at 10 to 40 m / s. In addition, it is preferable to carry out preliminary mixing so that the external additive is uniformly attached to the surface of the resin particles. As a method for controlling the temperature, it is preferable to adjust the temperature to a required temperature using warm water or the like from the outside.
[0045]
The temperature measurement method is to measure the temperature of the portion where the toner is flowing while the toner is being stirred and mixed. Moreover, it is preferable to distribute | circulate cold water after a fixing process and to perform a cooling and crushing process.
[0046]
As a method of controlling the degree of immobilization of the external additive on the colored particle surface, the colored particles and the external additive are stirred and mixed under a temperature condition of Tg−20 ≦ (stirring temperature) ≦ Tg + 20, and the mechanical impact force The external additive particles can be uniformly attached to the surface of the colored particles by adjusting the arbitrary time while imparting.
[0047]
Tg mentioned here refers to the glass transition temperature of the toner or the binder resin constituting the toner. The glass transition temperature was measured using a DSC7 differential scanning calorimeter (Perkin Elmer). The measurement method is to raise the temperature from 0 ° C. to 200 ° C. at 10 ° C./min, then cool from 200 ° C. to 0 ° C. at 10 ° C./min to erase the previous history, and then from 0 ° C. at 10 ° C./min. The temperature was raised to 200 ° C., the endothermic peak temperature of the second heat was determined, and this was taken as Tg. When there are a plurality of endothermic peaks, the temperature of the main endothermic peak was defined as Tg.
[0048]
The Tg of the toner or the binder resin constituting the toner is preferably 40 to 70 ° C. When the temperature is lower than 40 ° C., the storage stability of the toner is poor and aggregation occurs. If it is higher than 70 ° C., it is not preferable from the viewpoints of fixability and productivity.
[0049]
From the viewpoint of imparting fluidity, an external additive may be further externally added after controlling the adhesion of the external additive. However, it is necessary that the turbidity of the toner falls within the scope of the present invention.
[0050]
About the measuring method of the number average particle diameter of the said external additive, it observed using the transmission electron microscope and displayed using what was measured by the image analysis.
[0051]
The composition of the external additive is not particularly limited, and any external additive can be used.
[0052]
For example, various inorganic oxides, nitrides, borides and the like are preferably used as the inorganic external additive. For example, silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide, Examples thereof include boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride.
[0053]
Further, the inorganic external additive may be subjected to a hydrophobic treatment. When performing the hydrophobizing treatment, the hydrophobizing treatment is preferably performed by using a so-called coupling agent such as various titanium coupling agents and silane coupling agents, and higher fatty acid metal salts such as aluminum stearate, zinc stearate, calcium stearate and the like. Those subjected to a hydrophobizing treatment with the use of are preferably used.
[0054]
In addition, when the resin external additive is used, the composition is not particularly limited. In general, vinyl-based organic external additive particles and external additive particles such as melamine / formaldehyde condensate, polyester, polycarbonate, polyamide, and polyurethane are preferable. This is because it can be easily produced by a production method such as an emulsion polymerization method or a suspension polymerization method.
[0055]
Next, the toner preferably used in the present invention will be described.
The toner of the present invention preferably has a number average particle diameter of 3 to 8 μm. When the toner particles are formed by a polymerization method, this particle size is determined in the toner production method described in detail later, in the concentration of the aggregating agent, the amount of organic solvent added, or the fusing time, and further the composition of the polymer itself. Can be controlled by.
[0056]
When the number average particle size is 3 to 8 μm, toner particles having a large adhesion force that adheres to the photoreceptor and causes filming are reduced, and the transfer efficiency is increased to improve the image quality of the halftone. Image quality such as fine lines and dots is improved.
[0057]
The particle size distribution of the toner used in the present invention is a number standard in which the natural logarithm lnD is taken on the horizontal axis when the particle size of the toner particles is D (μm), and the horizontal axis is divided into a plurality of classes at intervals of 0.23. In the histogram showing the particle size distribution of toner particles, the relative frequency of toner particles (m ₁ ) And the relative frequency (m of toner particles contained in the next most frequent class after the most frequent class) ₂ ) And the toner (M) is preferably 70% or more.
[0058]
Relative frequency (m ₁ ) And relative frequency (m ₂ ) Is 70% or more, the dispersion of the particle size distribution of the toner particles is narrowed. Therefore, by using the toner in the image forming process, the primary transfer property and secondary transfer of the toner image are performed. And the occurrence of selective development can be reliably suppressed.
[0059]
In the present invention, the histogram showing the particle size distribution based on the number is a natural logarithm lnD (D: particle size of individual toner particles) having a plurality of classes (0 to 0.23: 0.23) at intervals of 0.23. 0.46: 0.46-0.69: 0.69-0.92: 0.92-1.15: 1.15-1.38: 1.38-1.61: 1.61-1. 84: 1.84 to 2.07: 2.07 to 2.30: 2.30 to 2.53: 2.53 to 2.76, and so on). This histogram is prepared by transferring the particle size data of a sample measured by a Coulter Multisizer to a computer via an I / O unit according to the following conditions and using the particle size distribution analysis program in the computer. is there.
[0060]
〔Measurement condition〕
(1) Aperture: 100 μm
(2) Sample preparation method: Electrolyte [ISOTON R-11 (manufactured by Coulter Scientific Japan)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) was added and stirred, and a measurement sample 10-20 mg was added thereto. Add This system is prepared by dispersing for 1 minute with an ultrasonic disperser.
[0061]
The toner used in the present invention preferably has a volume average particle diameter of 3 to 8 μm. The volume average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II, Coulter Multisizer, SLAD1100 (a laser diffraction particle size measuring device manufactured by Shimadzu Corporation), or the like. In the Coulter Counter TA-II and Coulter Multisizer, the particle size distribution in the range of 2.0 to 40 μm was measured and obtained using an aperture with an aperture diameter of 100 μm.
[0062]
The method for producing this toner is not particularly limited. However, a polymerized toner (also referred to as a polymerized toner) is preferable because it is simple as a production method and has excellent uniformity compared with a pulverized toner.
[0063]
The term “polymerized toner” means a toner obtained by forming a resin for a toner binder and forming a toner shape by polymerization of a raw material monomer of the binder resin and subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a subsequent step of fusing particles. Since the polymerized toner is produced by uniformly dispersing the raw material monomers in an aqueous system and then producing the toner, a toner having a uniform toner particle size distribution and shape can be obtained.
[0064]
In any case, the object of the present invention can be achieved as long as it satisfies the requirements of the present invention, whether it is a pulverized toner or a polymerized toner.
<< Constitution and Manufacturing Method of Toner Used in the Present Invention >>
The toner production method used in the present invention is the most commonly used pulverization method, that is, a binder resin, a colorant, and various additives added as necessary are kneaded and classified after classification. Alternatively, resin particles containing a release agent and a colorant may be synthesized and produced in a medium.
[0065]
As a method for fusing in an aqueous medium, for example, methods described in JP-A-63-186253, JP-A-63-282749, JP-A-7-146582, etc. For example, a method of forming it by wearing can be given.
[0066]
The resin particles used here preferably have a weight average particle size of 50 to 2000 nm. These resin particles may be formed by any granulation polymerization method such as emulsion polymerization, suspension polymerization, seed polymerization, etc., but preferably used is emulsification. It is a polymerization method.
[0067]
Hereinafter, conventionally known polymerizable monomers can be used as monomers used for the production of the resin in any production method. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.
[0068]
The binder resin is not particularly limited, and a generally known binder resin such as a styrene resin, an acrylic resin, a styrene-acrylic resin, a polyester resin, a styrene-butadiene resin, or an epoxy resin should be used. Can do.
[0069]
Examples of the resin constituting the styrene resin, acrylic resin, and styrene-acrylic resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4- Dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p- styrene or styrene derivatives such as n-decylstyrene, pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-methacrylate -Octyl, 2-ethylhexyl methacrylate, Methacrylic acid ester derivatives such as stearyl acrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-acrylate -Specific examples of acrylic acid ester derivatives such as butyl, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, etc. As monomers constituting the resin, these can be used alone or in combination.
[0070]
Specific examples of other vinyl polymers include olefins such as ethylene, propylene and isobutylene, halogen-based vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride, and propionic acid. Vinyl esters such as vinyl, vinyl acetate and vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole and N-vinyl N-vinyl compounds such as indole and N-vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, acrylonitrile, methacrylonitrile, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, methacrylate Amide, N- methacrylamide, there are acrylic acid or methacrylic acid derivatives such as N- octadecyl acrylamide. These vinyl monomers can be used alone or in combination.
[0071]
Furthermore, examples of monomers for obtaining a carboxylic acid polymer with a styrene-acrylic resin (vinyl resin) include acrylic acid, methacrylic acid, α-ethylacrylic acid, fumaric acid, maleic acid, itaconic acid, silica. Cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, cinnamic acid anhydride, alkenyl succinic acid methyl half ester and the like.
[0072]
Further, a cross-linking agent such as divinylbenzene, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate may be added.
[0073]
The polyester resin is a resin obtained by condensation polymerization of a divalent or higher carboxylic acid and a divalent or higher alcohol component. Examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutamic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n- Examples include dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, and the like, and these acid anhydrides can also be used.
[0074]
Examples of the divalent alcohol component constituting the polyester resin include polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) Etherified bisphenol such as -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol 1,4 butenediol, neopentyl glycol, 1,5-pentane glycol, 1,6-hexane glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A Bisphenol Z, hydrogenated bisphenol A, and the like.
[0075]
Examples of the polyester resin having a crosslinked structure include the following trivalent carboxylic acids such as 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid. 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra ( Methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, emporic trimer acid, and the like. These acid anhydrides or polyhydric alcohol components, specifically sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaery Ritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, tri A crosslinked polyester resin can also be obtained by adding methylolpropane, 1,3,5-trihydroxymethylbenzene or the like.
[0076]
In the present invention, black toner (hereinafter also referred to as toner Bk), yellow toner (hereinafter also referred to as toner Y), magenta toner (hereinafter also referred to as toner M), cyan toner (hereinafter referred to as toner C). Examples of the colorant used in the present invention include inorganic pigments and organic pigments.
[0077]
A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.
[0078]
Examples of black pigments include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
[0079]
These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0080]
When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.
[0081]
Conventionally known organic pigments can also be used. Specific organic pigments are exemplified below.
[0082]
Examples of the magenta or red pigment (magenta color system) include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
[0083]
Examples of pigments for orange or yellow (yellow type) include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.
[0084]
Examples of pigments for green or cyan (cyan color) include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
[0085]
These organic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0086]
The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.
[0087]
To the toner obtained in the present invention, so-called external additives can be added and used for the purpose of improving fluidity and improving cleaning properties. As described above, these external additives are not particularly limited, and various inorganic particles, organic particles and lubricants can be used.
[0088]
In addition to the external additive particles, a lubricant may be added to the toner as an external additive. Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.
[0089]
The addition amount of these lubricants is preferably about 0.1 to 5% by mass with respect to the toner.
In the toner forming step, the above-described external additives may be added to the toner particles obtained above for the purpose of improving fluidity, chargeability, and cleaning properties, for example. As a method for adding the external additive, various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.
[0090]
In addition to the binder resin and the colorant, the toner may be added with a material capable of imparting various functions as an additive for the toner. Specific examples include a release agent and a charge control agent.
[0091]
In addition, as a mold release agent, various well-known things, specifically, olefin type waxes, such as polypropylene and polyethylene, these modified substances, natural waxes, such as carnauba wax and rice wax, fatty acid bisamide, etc. Examples thereof include amide waxes. It has already been mentioned that these are added as release agent particles and are preferably salted out / fused together with resin and colorant.
[0092]
Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
[0093]
<Developer>
The toner used in the present invention may be used as a one-component developer or a two-component developer, but is preferably a two-component developer.
[0094]
When used as a one-component developer, there is a method in which the toner is used as it is as a non-magnetic one-component developer. Usually, however, the toner particles contain about 0.1 to 5 μm of magnetic particles as a magnetic one-component developer. Use. As a method for its inclusion, it is usually contained in non-spherical particles in the same manner as the colorant.
[0095]
Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead are used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 60 μm.
[0096]
The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
[0097]
The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like can be used. it can.
[0098]
Next, the photoconductor used in the present invention will be described in detail.
The electrophotographic photosensitive member used in the image forming apparatus of the present invention may be either an inorganic photosensitive member or an organic photosensitive member. However, when forming a latent image, color sensitivity to laser light used for image exposure, An organic photoreceptor is preferable from the viewpoint of good productivity.
[0099]
Here, the organic photoconductor means an electrophotographic photoconductor formed by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the configuration of the electrophotographic photoconductor. It contains all known organic electrophotographic photoreceptors such as a photoreceptor composed of an organic charge generating material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function.
[0100]
In the electrophotographic photoreceptor used in the image forming apparatus of the present invention, it is preferable that the surface of the photoreceptor is made to have low surface energy properties and the transferability of toner from the photoreceptor to the intermediate transfer member is improved. As a measure for this, one is to make the surface layer of the photoreceptor into a surface layer containing fluorine resin particles in the present invention, and the other is to supply a surface energy reducing agent to the surface of the photoreceptor. As a result, the contact angle of water on the surface of the photosensitive member can be 90 ° or more, the surface energy of the photosensitive member can be reduced, and the transferability of toner from the photosensitive member to the intermediate transfer member can be improved. By using both the contact angle of water on the surface of the photoreceptor to 90 ° or more (preferably 95 ° or more) and the use of the toner group having the toner turbidity described above, an intermediate transfer member is used. The transfer efficiency of both the primary transfer property and secondary transfer property of the toner of the image forming apparatus using the toner is mentioned. Due to the synergistic effect, the sharpness is good for both the character image and the color image, and the color reproduction is good. An electrophotographic image can be provided.
[0101]
Examples of the fluorine resin particles include, for example, polytetrafluoroethylene, polyvinylidene fluoride, polytrifluoroethylene chloride, polyvinyl fluoride, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene- Examples include resin particles such as hexafluoropropylene copolymer, polyethylene-trifluoride ethylene copolymer, polytetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, and volume average particle diameter. The thickness is preferably 0.05 to 10 μm, more preferably 0.1 to 5 μm. The amount of the fluororesin particles contained in the photoreceptor is preferably 0.1 to 90% by mass, more preferably 1 to 50% by mass with respect to the binder resin of the surface layer of the photoreceptor. If it is less than 1%, sufficient photosensitive durability and lubricity cannot be imparted to the photosensitive layer, so that the primary transferability of the toner is small, image density is reduced, transfer is lost, sharpness is deteriorated, etc. Likely to happen. If it exceeds 90% by mass, the formation of the surface layer tends to be difficult.
[0102]
The volume average particle diameter of the fluororesin particles is measured by a laser diffraction / scattering particle size distribution measuring apparatus “LA-700” (manufactured by Horiba, Ltd.). The surface contact angle of the photosensitive member is measured by using a contact angle meter (CA-DT-A type: manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 20 ° C. and 50% RH.
[0103]
Next, the surface energy reducing agent will be described. Here, the surface energy reducing agent is a substance that adheres to the surface of the electrophotographic photosensitive member and reduces the surface energy of the electrophotographic photosensitive member. Specifically, the surface energy reducing agent adheres to the surface of the electrophotographic photosensitive member. A material that increases the contact angle (contact angle with respect to pure water) by 1 ° or more.
[0104]
By the way, a fatty acid metal salt is mentioned as a surface energy reducing agent.
The surface energy reducing agent is not limited to a material such as a fatty acid metal salt as long as it is a material that increases the contact angle (contact angle with respect to pure water) of the surface of the electrophotographic photosensitive member by 1 ° or more.
[0105]
The surface energy reducing agent used in the present invention is most preferably a fatty acid metal salt as a material having spreadability to the surface of the photoreceptor and uniform film forming performance. The fatty acid metal salt is preferably a metal salt of a saturated or unsaturated fatty acid having 10 or more carbon atoms. Examples include aluminum stearate, indium stearate, gallium stearate, zinc stearate, lithium stearate, magnesium stearate, sodium stearate, aluminum palmitate, aluminum oleate, and the like, more preferably metal stearate. .
[0106]
Among the fatty acid metal salts, fatty acid metal salts having a high flow tester flow rate are particularly high in cleavage and can form a fatty acid metal salt layer more effectively on the surface of the photoreceptor. The outflow rate range is 1 x 10 ^-7 1 × 10 or more ^-1 The following is preferred, 5 × 10 ^-Four 1 × 10 or more ^-2 Most preferred is The flow rate of the flow tester was measured using a Shimadzu flow tester “CFT-500” (manufactured by Shimadzu Corporation).
[0107]
FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.
[0108]
This color image forming apparatus is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units (image forming units) 10Y, 10M, 10C, 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.
[0109]
An image forming unit 10Y that forms a yellow image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a primary transfer unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.
[0110]
The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.
[0111]
Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A sheet P as a recording material (a support for carrying a fixed final image: for example, plain paper, transparent sheet, etc.) housed in the sheet feeding cassette 20 is fed by a sheet feeding means 21 and has a plurality of intermediate rollers. After passing through 22A, 22B, 22C, 22D and the registration roller 23, it is conveyed to the secondary transfer roller 5A as the secondary transfer means, and is secondarily transferred onto the paper P, and the color images are collectively transferred. The paper P on which the color image has been transferred is fixed by the fixing unit 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.
[0112]
On the other hand, after the color image is transferred onto the sheet P by the secondary transfer roller 5A as the secondary transfer unit, the residual toner is removed by the cleaning unit 6A from the endless belt-shaped intermediate transfer body 70 from which the sheet P is separated by curvature.
[0113]
During the image forming process, the primary transfer roller 5Bk is always in pressure contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.
[0114]
The secondary transfer roller 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the sheet P passes through the secondary transfer roller 5A and secondary transfer is performed.
[0115]
Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.
[0116]
The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.
[0117]
The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6A. Consists of.
[0118]
FIG. 2 shows an example of the cleaning means for the intermediate transfer member.
As shown in FIG. 2, the intermediate transfer member cleaning means 6A is composed of a blade 61 attached to a bracket 62 that is controlled to rotate around a support shaft 63. By changing the spring load or weight load, the roller 6 The blade pressing force to 71 can be adjusted.
[0119]
The image forming units 10Y, 10M, 10C, and 10Bk and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.
[0120]
A support rail 82 </ b> L on the left side of the housing 8 in the figure is disposed on the left side of the endless belt-shaped intermediate transfer body 70 and in the upper space of the fixing unit 24. The support rail 82R on the right side of the housing 8 in the drawing is disposed near the lower part of the lowermost developing means 4Bk. The support rail 82R is disposed at a position that does not hinder the operation of attaching and detaching the developing units 4Y, 4M, 4C, and 4Bk to the housing 8.
[0121]
The right side of the photoconductors 1Y, 1M, 1C, and 1Bk in the casing 8 is surrounded by the developing means 4Y, 4M, 4C, and 4Bk, and the lower side in the figure is the charging means 2Y, 2M, 2C, and 2Bk, and the cleaning means 6Y. , 6M, 6C, 6Bk, etc., and the left side in the figure is surrounded by an endless belt-shaped intermediate transfer body 70.
[0122]
Among them, the photosensitive member, the cleaning unit, the charging unit and the like form one photosensitive unit, and the developing unit and the toner replenishing device form one developing unit.
[0123]
FIG. 3 is a layout diagram showing the positional relationship among the photosensitive member, the endless belt-shaped intermediate transfer member, and the primary transfer roller. The primary transfer rollers 5Y, 5M, 5C, and 5Bk are pressed from the back surface of the endless belt-like intermediate transfer body 70 as an intermediate transfer body to each of the photoreceptors 1Y, 1M, 1C, and 1Bk, as shown in the layout diagram of FIG. In addition, primary transfer rollers 5Y, 5M, and 5C on the downstream side in the photoconductor rotation direction with respect to the contact point between the endless belt-like intermediate transfer body 70 as an intermediate transfer body when not pressed and the photoconductors 1Y, 1M, 1C, and 1Bk. 5Bk are arranged and pressed to the respective photoreceptors 1Y, 1M, 1C, and 1Bk. At this time, the endless belt-shaped intermediate transfer body 70 as an intermediate transfer body is bent along the outer periphery of each of the photoreceptors 1Y, 1M, 1C, 1Bk, and is most downstream in the contact area between the photoreceptor and the endless belt-shaped intermediate transfer body 70. The primary transfer rollers 5Y, 5M, 5C, and 5Bk are arranged on the side.
[0124]
FIG. 4 is a layout diagram showing the positional relationship among the backup roller, the endless belt-shaped intermediate transfer member, and the secondary transfer roller. As shown in the layout diagram of FIG. 4, the secondary transfer roller 5 </ b> A is formed from the center of contact between the endless belt-shaped intermediate transfer body 70 and the backup roller 74 as an intermediate transfer body when not pressed by the secondary transfer roller 5 </ b> A. Also, it is desirable to arrange the backup roller 74 on the upstream side in the rotation direction.
[0125]
As the intermediate transfer member, a polymer film such as polyimide, polycarbonate, PVdF, or a synthetic rubber such as silicone rubber or fluororubber added with a conductive filler such as carbon black is used. Either a belt shape may be used, but a belt shape is preferable from the viewpoint of freedom in device design.
[0126]
The surface of the intermediate transfer member is preferably appropriately roughened. By setting the 10-point surface roughness Rz of the intermediate transfer member to 0.5 to 2 μm, the surface energy reducing agent supplied to the photosensitive member is taken into the surface of the intermediate transfer member and the toner adhesion on the intermediate transfer member is reduced. It becomes easy to improve the transfer rate of the secondary transfer of toner from the intermediate transfer member to the recording material. In this case, the effect tends to be greater when the ten-point surface roughness Rz of the intermediate transfer member is larger than the ten-point surface roughness Rz of the photosensitive member.
[0127]
The present invention is characterized in that the latent image on the electrophotographic photosensitive member is developed and visualized as a toner image while applying a surface energy reducing agent to the surface of the electrophotographic photosensitive member. As a method of applying to the photoreceptor, there is a method of mixing a developer with a surface energy reducing agent and applying the developer to the photoreceptor, but in the present invention, it is preferable to use a method different from such a method. That is, when the surface energy reducing agent is mixed with the developer, the mixing affects the developing characteristics such as charging characteristics and fluidity of the toner, and it is difficult to achieve a sufficient mixing amount. Speaking of the relationship with the toner of the present invention, by mixing a surface energy reducing agent with the developer, the effect of preventing transfer loss and character dust generation is likely to be significantly reduced. It is preferable to use different means and methods.
[0128]
That is, the present invention preferably has an agent applying means for supplying a surface energy reducing agent to the surface of the electrophotographic photosensitive member. The agent applying means can be installed at an appropriate position around the electrophotographic photosensitive member. However, in order to effectively use the installation space, a part of the charging means, developing means, and cleaning means shown in FIG. May be installed. Hereinafter, examples in which the agent providing means is used in combination with the cleaning means will be given.
[0129]
FIG. 5 is a block diagram of the cleaning means installed in the image forming unit of the present invention.
[0130]
The cleaning means is used as a cleaning means such as 6Y, 6M, 6C, 6Bk in FIG. The cleaning blade 66A of FIG. 5 is attached to the support member 66B. A rubber elastic body is used as the material of the cleaning blade, and urethane rubber, silicon rubber, fluorine rubber, chloropyrene rubber, butadiene rubber, and the like are known as the material. This is particularly preferable in terms of excellent wear characteristics as compared with rubber.
[0131]
On the other hand, the support member 66B is configured by a plate-like metal member or a plastic member. As the metal member, a stainless steel plate, an aluminum plate, a damping steel plate or the like is preferable.
[0132]
In the present invention, it is preferable that the tip of the cleaning blade that is in pressure contact with the surface of the photoconductor is in pressure contact with a load applied in a direction opposite to the rotation direction of the photoconductor (counter direction). As shown in FIG. 5, it is preferable to form a pressure contact surface when the tip of the cleaning blade is pressed against the photosensitive member.
[0133]
Preferable values of the contact load P and contact angle θ of the cleaning blade to the photosensitive member are P = 5 to 40 N / m and θ = 5 to 35 °.
[0134]
The contact load P is a normal vector value of the pressure contact force P ′ when the cleaning blade 66A is brought into contact with the photosensitive drum 1.
[0135]
The contact angle θ represents an angle formed between the tangent line X at the contact point A of the photosensitive member and the blade before deformation (shown by a dotted line in the drawing). Reference numeral 66E denotes a rotating shaft that enables the support member to rotate, and 66G denotes a load spring.
[0136]
Further, as shown in FIG. 5, the free length L of the cleaning blade represents the length of the tip of the blade before deformation from the position of the end B of the support member 66B. A preferable value of the free length is L = 6 to 15 mm. The thickness t of the cleaning blade is preferably 0.5 to 10 mm. Here, the thickness of the cleaning blade indicates a direction perpendicular to the bonding surface of the support member 66B as shown in FIG.
[0137]
A brush roll 66C also serving as an agent applying unit is used for the cleaning unit in FIG. The brush roll has a function as an agent applying means for supplying a surface energy reducing agent to the photosensitive member, as well as a function of removing the toner adhering to the photosensitive member 1 and a function of collecting the toner removed by the cleaning blade 66A. That is, the brush roll comes into contact with the photosensitive member 1, and the traveling direction of the brush roller rotates in the same direction as that of the photosensitive member, thereby removing toner and paper dust on the photosensitive member and removing the toner with the cleaning blade 66 </ b> A. Is collected and collected by the conveying screw 66J. In this route, it is preferable to remove the removed matter such as toner transferred from the photosensitive member 1 to the brush roll 66C by bringing the flicker 66I as a removing means into contact with the brush roll 66C. Further, the toner adhering to the flicker is removed by the scraper 66D, and the toner is collected by the conveying screw 66J. The collected toner is taken out as a waste, or is transported to a developing device via a recycling pipe (not shown) for toner recycling and reused. As the material of the flicker 66I, a metal tube such as stainless steel or aluminum is preferably used. On the other hand, as the scraper 66D, an elastic plate such as a phosphor bronze plate, a polyethylene terephthalate plate, or a polycarbonate plate is used, and it is preferable that the tip is brought into contact with a counter system that forms an acute angle with respect to the flicker rotation direction.
[0138]
Further, a surface energy reducing agent (solid material such as zinc stearate) 66K is attached to a brush roll by being pressed by a spring load 66S. A surface energy reducing agent is supplied to the surface of the substrate.
[0139]
As the brush roll 66C, a conductive or semiconductive brush roll is used.
[0140]
Although any material can be used as the brush constituent material of the brush roll used in the present invention, it is preferable to use a fiber-forming high molecular polymer that is hydrophobic and has a high dielectric constant. Examples of such a polymer include rayon, nylon, polycarbonate, polyester, methacrylic acid resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polypropylene, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, and vinylidene chloride. -Acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol formaldehyde resin, styrene-alkyd resin, polyvinyl acetal (e.g. polyvinyl Butyral). These binder resins can be used alone or as a mixture of two or more. Particularly preferred are rayon, nylon, polyester, acrylic resin and polypropylene.
[0141]
In addition, the brush may be conductive or anti-conductive, and a constituent material containing a low-resistance substance such as carbon and adjusted to an arbitrary specific resistance can be used.
[0142]
The specific resistance of the bristle of the brush roll was measured at a normal temperature and normal humidity (temperature of 26 ° C., relative humidity of 50%) with a voltage of 500 V applied to both ends of a single bristle having a length of 10 cm. ¹ Ωcm to 10 ⁶ Those within the range of Ωcm are preferred.
[0143]
That is, the brush roll is made of 10 on a core material such as stainless steel. ¹ Ωcm to 10 ⁶ It is preferable to use conductive or semiconductive brush hair having a specific resistance of Ωcm. 10 ¹ When the specific resistance is lower than Ωcm, banding or the like due to discharge is likely to occur. 10 ⁶ If it is higher than Ωcm, the potential difference from the photosensitive member becomes low, and cleaning failure tends to occur.
[0144]
The thickness of one bristle used for the brush roll is preferably 5 to 20 denier. If it is less than 5 denier, the surface deposits cannot be removed because there is no sufficient scratching force. On the other hand, if the denier is greater than 20 denier, the brush becomes rigid, so that the surface of the photoconductor is damaged and wear progresses, thereby reducing the life of the photoconductor.
[0145]
Here, “denier” is a numerical value obtained by measuring the mass of a bristle (fiber) constituting the brush with a length of 9000 m in units of g (grams).
[0146]
The brush hair density of the brush is 4.5 × 10 ² / Cm ² ~ 2.0 × 10 ^Four / Cm ² (Number of brush hairs per square centimeter). 4.5 × 10 ² / Cm ² If it is less than 1, the rigidity is low and the rubbing force is weak, and the rubbing becomes uneven and the deposits cannot be removed uniformly. 2.0 × 10 ^Four / Cm ² If it is larger, it becomes rigid and the rubbing force becomes stronger, so that the photosensitive member is worn, and a defective image such as fogging due to sensitivity reduction or black streaks due to scratches is generated.
[0147]
The amount of biting into the photoreceptor of the brush roll used in the present invention is preferably set to 0.4 to 1.5 mm, and more preferably 0.5 to 1.2 mm. This amount of biting means the load on the brush generated by the relative movement of the photosensitive drum and the brush roll. This load corresponds to the rubbing force received from the brush when viewed from the photoconductor drum, and defining the range means that the photoconductor needs to be rubbing with an appropriate force.
[0148]
The amount of biting refers to the length of biting into the interior when it is assumed that the brush bristles have entered the interior linearly without bending on the surface of the photoreceptor when the brush is brought into contact with the photoreceptor.
[0149]
In the photoreceptor supplied with the surface energy reducing agent, the rubbing force on the photoreceptor surface by the brush is small, so if the amount of biting is less than 0.4 mm, filming of toner or paper dust on the photoreceptor surface is suppressed. Cannot be achieved, and defects such as unevenness occur on the image. On the other hand, if it is larger than 1.5 mm, the amount of abrasion on the surface of the photoconductor due to the brush is too great, the amount of wear on the photoconductor increases, fogging due to a decrease in sensitivity occurs, and scratches occur on the surface of the photoconductor. A streak failure may occur on the image.
[0150]
As the core material of the roll part used for the brush roll, metals such as stainless steel and aluminum, paper, plastics and the like are mainly used, but are not limited thereto.
[0151]
It is preferable that the brush roll used by this invention is the structure which installed the brush through the contact bonding layer on the surface of the column-shaped core material.
[0152]
The brush roll preferably rotates so that its abutting portion moves in the same direction as the surface of the photoreceptor. When the contact portion moves in the reverse direction, if excessive toner is present on the surface of the photosensitive member, the toner removed by the brush roll may spill and stain the recording material or apparatus.
[0153]
When the photoconductor and the brush roll move in the same direction as described above, the surface speed ratio between the two is preferably a value within a range of 1: 1 to 1-2. If the rotation speed of the brush roll is slower than that of the photoconductor, the toner removal capability of the brush roll will be reduced, so cleaning failure will easily occur. If it is faster than the photoconductor, the toner removal capability will be excessive and blade bounding or turning will occur It becomes easy to do.
[0154]
【Example】
Next, embodiments of the present invention will be specifically described. However, the configuration of the present invention is not limited to this.
(Development of developer)
Preparation of toner and developer
(Production of toners 1Bk, 1Ya, 1Yb, 1M, 1C)
0.90 kg of sodium n-dodecyl sulfate and 10.0 liters of pure water were added and dissolved by stirring. To this solution, 1.20 kg of Legal 330R (Cabot carbon black) was gradually added and stirred well for 1 hour, followed by continuous dispersion for 20 hours using a sand grinder (medium disperser). This is referred to as “colorant dispersion 1”.
[0155]
A solution composed of 0.055 kg of sodium dodecylbenzenesulfonate and 4.0 liters of ion-exchanged water is referred to as “anionic surfactant solution A”.
[0156]
A solution composed of 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct and 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution B”.
[0157]
A solution obtained by dissolving 223.8 g of potassium persulfate in 12.0 liters of ion-exchanged water is referred to as “initiator solution C”.
[0158]
A GL (glass lining) reaction kettle with a volume of 100 liters equipped with a temperature sensor, a condenser tube, and a nitrogen introducing device was added to a WAX emulsion (a polypropylene emulsion having a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration = 29. 9%) 3.41 kg, the total amount of “anionic surfactant solution A” and the total amount of “nonionic surfactant solution B” were added, and stirring was started. Subsequently, 44.0 liters of ion exchange water was added.
[0159]
Heating was started and when the liquid temperature reached 75 ° C., the entire amount of “Initiator Solution C” was added dropwise. Thereafter, while controlling the liquid temperature at 75 ° C. ± 1 ° C., 12.1 kg of styrene, 2.88 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 548 g of t-dodecyl mercaptan were added dropwise. After completion of the dropwise addition, the liquid temperature was raised to 80 ° C. ± 1 ° C. and stirring was performed for 6 hours. Next, the liquid temperature was cooled to 40 ° C. or less, stirring was stopped, and filtration was performed with a pole filter to obtain a latex. This is designated as “Latex-A”.
[0160]
The glass transition temperature of the resin particles in Latex-A was 57 ° C., the softening point was 121 ° C., the molecular weight distribution was weight average molecular weight = 12.7 million, and the weight average particle size was 120 nm.
[0161]
A solution prepared by dissolving 0.055 kg of sodium dodecylbenzenesulfonate in 4.0 liters of ion-exchanged pure water is referred to as “anionic surfactant solution D”.
[0162]
Further, a solution obtained by dissolving 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct in 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution E”.
[0163]
A solution obtained by dissolving 200.7 g of potassium persulfate (manufactured by Kanto Chemical Co., Ltd.) in 12.0 liters of ion-exchanged water is referred to as “initiator solution F”.
[0164]
A WAX emulsion (a polypropylene emulsion with a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration of 29.9%) was added to a 100 liter GL reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device and a comb baffle. 3.41 kg, the total amount of “anionic surfactant solution D” and the total amount of “nonionic surfactant solution E” were added, and stirring was started.
[0165]
Next, 44.0 liters of ion exchange water was added. Heating was started, and when the liquid temperature reached 70 ° C., “initiator solution F” was added. Then, a solution prepared by previously mixing 11.0 kg of styrene, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 9.02 g of t-dodecyl mercaptan was dropped. After completion of the dropwise addition, the liquid temperature was controlled at 72 ° C. ± 2 ° C., and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours. The liquid temperature was cooled to 40 ° C. or lower, and stirring was stopped. The filtrate is filtered through a pole filter, and this filtrate is designated as “Latex-B”.
[0166]
The glass transition temperature of the resin particles in Latex-B was 58 ° C., the softening point was 132 ° C., the molecular weight distribution was weight average molecular weight = 245,000, and the weight average particle size was 110 nm.
[0167]
A solution obtained by dissolving 5.36 kg of sodium chloride as a salting-out agent in 20.0 liters of ion-exchanged water is referred to as “sodium chloride solution G”.
[0168]
A solution obtained by dissolving 1.00 g of a fluorine-based nonionic surfactant in 1.00 liter of ion-exchanged water is referred to as “nonionic surfactant solution H”.
[0169]
In a 100 liter SUS reaction kettle equipped with a temperature sensor, cooling pipe, nitrogen introduction device, particle size and shape monitoring device, latex-A = 20.0 kg, latex-B = 5.2 kg, and colorant prepared above Dispersion 1 = 0.4 kg and ion-exchanged water 20.0 kg were added and stirred. Next, the mixture was heated to 40 ° C., and sodium chloride solution G, 6.00 kg of isopropanol (manufactured by Kanto Chemical Co., Inc.) and nonionic surfactant solution H were added in this order. Then, after standing for 10 minutes, the temperature rise was started, the temperature was raised to a liquid temperature of 85 ° C. in 60 minutes, and the particles were heated and stirred at 85 ± 2 ° C. for 0.5 to 3 hours while being salted out / fused. Diameter growth (salting out / fusion process). Next, 2.1 liters of pure water was added to stop particle size growth, and a fused particle dispersion was prepared.
[0170]
In a 5-liter reaction vessel equipped with a temperature sensor, a cooling pipe, a particle size and shape monitoring device, 5.0 kg of the fused particle dispersion prepared above was placed, and the liquid temperature was 85 ° C. ± 2 ° C. The shape was controlled by heating and stirring for 5 to 15 hours (shape control step). Then, it cooled to 40 degrees C or less, and stopped stirring. Next, using a centrifugal separator, classification is performed in the liquid by a centrifugal sedimentation method, followed by filtration through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid. Subsequently, wet cake-like non-spherical particles were collected by filtration from the associating liquid using Nutsche. Thereafter, it was washed with ion exchange water. The non-spherical particles were dried at a suction air temperature of 60 ° C. using a flash jet dryer and then dried at a temperature of 60 ° C. using a fluidized bed dryer. To 100 parts by mass of the obtained colored particles, 0.5 part by mass of hydrophobic silica (degree of hydrophobicity = 75 / number average primary particle size = 12 nm) and 0.25 part by mass of 0.05 μm titanium oxide are added. The toner was mixed at a peripheral speed of a Henschel mixer at 40 m / s at 52 ° C. for 10 minutes to obtain “Toner 1Bk”.
[0171]
In the production of toner 1Bk, C.I. I. “Toner 1Ya” was obtained in the same manner except that CI Pigment Yellow 185 was used. In addition, “Toner 1Yb” was obtained by slightly reducing the peripheral speed of the Henschel mixer.
[0172]
In the production of toner 1Bk, C.I. I. “Toner 1M” was obtained in the same manner except that CI Pigment Red 122 was used.
[0173]
In the production of toner 1Bk, C.I. I. “Toner 1C” was obtained in the same manner except that CI Pigment Blue 15: 3 was used. Number average particle diameters of toners 1Bk, 1Ya, 1M, and 1C, M (m ₁ + M ₂ ) Measurement results are shown in Table 1, and toner turbidity measurement results are shown in Table 2. The number average particle diameter of toner 1Yb, M (m ₁ + M ₂ ) Was almost the same as toner 1Ya.
(Production of toners 2Bk, 2Ya to 2Yf, 2M, 2C)
In the preparation of the toners 1Bk, 1Y, 1M, and 1C, hydrophobic silica (hydrophobic degree = 75 / number average primary particle size = 12 nm) is changed to hydrophobic silica (hydrophobic degree = 77 / number average primary particle size = 20 nm). The toners 2Bk, 2Ya to 2Yf, 2M, and 2C were produced in the same manner except that the peripheral speed and time of the Henschel mixer were changed. Table 2 shows the measurement results of the turbidity of the toners 2Bk, 2Ya to 2Yf, 2M, and 2C. The number average particle diameter of these toners, M (m ₁ + M ₂ ) Basically correspond to the respective colors of the toners 1Bk, 1Ya, 1M, and 1C (number average particle diameter of toner, M (m ₁ + M ₂ )) Was almost the same as the measurement result.
(Production of toners 3Bk, 3Ya-3Yd, 3M, 3C)
In the preparation of the toners 1Bk, 1Y, 1M, and 1C, the hydrophobic silica (degree of hydrophobicity = 75 / number average primary particle size = 12 nm) was changed from 0.5 parts by weight to 1.8 parts by weight. Toners 3Bk, 3Ya to 3Yd, 3M, and 3C were prepared in the same manner except that the peripheral speed and the mixing time were changed. Table 2 shows the measurement results of the turbidity of the toners 3Bk, 3Ya to 3Yd, 3M, and 3C. The number average particle diameter of these toners, M (m ₁ + M ₂ ) Were basically the same as the measurement results corresponding to the toners 1Bk, 1Ya, 1M, and 1C.
(Production of toners 4Bk, 4Ya to 4Yc, 4M, 4C)
In the preparation of the toners 1Bk, 1Y, 1M, and 1C, hydrophobic silica (hydrophobic degree = 75 / number average primary particle size = 12 nm) is changed from 0.5 parts by mass to hydrophobic silica (hydrophobic degree = 77 / number average). Toners 4Bk, 4Ya to 4Yc, 4M, and 4C were prepared in the same manner except that the primary particle size was changed to 1.8 parts by mass and the peripheral speed and mixing time of the Henschel mixer were changed. Table 2 shows the measurement results of the turbidity of the toners 4Bk, 4Ya to 4Yc, 4M, and 4C. The number average particle diameter of these toners, M (m ₁ + M ₂ ) Were basically the same as the measurement results corresponding to the toners 1Bk, 1Ya, 1M, and 1C.
(Production of toners 5Bk, 5Y, 5Ma to 5Mc, 5C)
In the preparation of the toners 1Bk, 1Y, 1M, and 1C, hydrophobic silica (hydrophobic degree = 75 / number average primary particle size = 12 nm) is changed from 0.5 part by mass to hydrophobic silica (hydrophobic degree = 77 / number average). Toners 5Bk, 5Y, 5Ma to 5Mc, and 5C were prepared in the same manner except that the primary particle size was changed to 3.3 parts by mass and the peripheral speed and mixing time of the Henschel mixer were changed. Table 2 shows the turbidity measurement results of the toners 5Bk, 5Y, 5Ma to 5Mc, and 5C. The number average particle diameter of these toners, M (m ₁ + M ₂ ) Were basically the same as the measurement results corresponding to the toners 1Bk, 1Ya, 1M, and 1C.
(Production of toners 6Bk, 6Y, 6M, and 6Ca to 6Cc)
Toners 6Bk, 6Y, 6M, and 6Ca to 6Cc were prepared in the same manner except that the peripheral speed and mixing time of the Henschel mixer were changed in the preparation of the toners 1Bk, 1Y, 1M, and 1C. Table 2 shows the measurement results of the turbidity of the toners 6Bk, 6Y, 6M, and 6Ca to 6Cc. The number average particle diameter of the toner, M (m ₁ + M ₂ ) Were basically the same as the measurement results corresponding to the toners 1Bk, 1Ya, 1M, and 1C.
[0174]
[Table 1]

[0175]
[Table 2]

[0176]
[Manufacture of developer]
45 μm ferrite carrier 100 coated with 10 parts by mass of toner 1Bk-1C, toner 2Bk-2C, toner 3Bk-3C, toner 4Bk-4C, toner 5Bk-5C, toner 6Bk-6Cc, and styrene-methacrylate copolymer. The developer 1Bk to 1C, the developer 2Bk to 2C, the developer 3Bk to 3C, the developer 4Bk to 4C, the developer 5Bk to 5C, and the developer 6Bk to 6Cc for evaluation were manufactured by mixing with parts by mass. .
[Production of photoconductor]
Photoconductors used in the examples were produced as follows (the photoconductors in each example were produced in a total of four or more because each image unit uses the same type of photoconductor).
[0177]
Production of photoreceptor 1
The following intermediate layer coating solution was prepared and applied on a washed cylindrical aluminum substrate by a dip coating method to form an intermediate layer having a dry film thickness of 0.3 μm.
[0178]
<Intermediate layer (UCL) coating solution>
Polyamide resin (Amilan CM-8000: manufactured by Toray Industries, Inc.) 60 g
1600 ml of methanol
The following coating solution components were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.2 μm on the intermediate layer.
[0179]
<Charge generation layer (CGL) coating solution>
Y-type titanyl phthalocyanine (X-ray diffraction of Cu-Kα characteristic X-ray
Maximum peak angle is 27.3 at 2θ) 60g
Silicone resin solution (KR5240, 15% xylene-butanol solution
700g made by Shin-Etsu Chemical)
2-butanone 2000ml
The following coating solution components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a thickness of 20 μm.
[0180]
<Charge transport layer (CTL) coating solution>
Charge transport material (4-methoxy-4 '-(4-methyl-α-phenylstyryl)
200 g of triphenylamine)
Bisphenol Z-type polycarbonate
(Iupilon Z300: Mitsubishi Gas Chemical Company) 300g
Hindered amine (Sanol LS2626: Sankyosha) 3g
Hydrophobic silica (number average primary particle size: 20 nm) 30 g
1,2-dichloroethane 2000ml
The contact angle of the surface of the photoreceptor 1 with respect to water was 84 °.
[0181]
Production of photoconductor 2
In the production of the photoconductor 1, the charge transport layer was similarly applied.
[0182]
<Surface protective layer>
Charge transport material (4-methoxy-4 '-(4-methyl-α-phenylstyryl)
200 g of triphenylamine)
Bisphenol Z-type polycarbonate
(Iupilon Z300: Mitsubishi Gas Chemical Company) 300g
Hindered amine (Sanol LS2626: Sankyosha) 3g
Hydrophobic silica (number average primary particle size: 20 nm) 8 g
100 g of polytetrafluoroethylene resin particles (average particle size 0.5 μm)
1-butanol 50g
Were mixed and dissolved to prepare a surface protective layer coating solution. This coating solution was applied onto the charge transport layer by a dip coating method, and heat-cured at 100 ° C. for 40 minutes to form a surface protective layer having a dry film thickness of 4 μm. The contact angle of water on the surface of the photoreceptor 2 with respect to water was 112 °.
[0183]
Preparation of photoreceptors 3-6
The surface contact angle is changed to 124 °, 118 °, 96 °, 91 ° by increasing or decreasing the amount of polytetrafluoroethylene resin particles (average particle size 0.5 μm) in the surface protective layer of the photoreceptor 2. Photoconductors 3, 4, 5, 6 were prepared.
[0184]
Preparation of surface energy reducing agents A to F
Sodium stearate was dissolved in water to prepare a 15% by mass solution. Further, zinc sulfate was dissolved in water to prepare a 25% by mass solution. A 2 liter receiving vessel with a stirring device having a turbine blade having a diameter of 6 cm was prepared, and the turbine blade was rotated at 350 rpm. A sodium stearate solution was charged into the receiving container, and the solution temperature was adjusted to 80 ° C. Next, a zinc sulfate solution heated to 80 ° C. was dropped into the receiving container over 30 minutes. The equivalent ratio of sodium stearate and zinc sulfate was 0.98, and the mixture was mixed so that the amount of metal soap slurry was 500 g. After the completion of charging the whole amount, the reaction was terminated by aging for 10 minutes at the temperature during the reaction. Next, the metal soap slurry thus obtained was washed twice with water and subsequently with water. The obtained metal soap cake was dried at a drying temperature of 110 ° C. and solidified at a pressure of 15 MPa. Thereafter, it was allowed to stand for 24 hours under an environmental condition of 30 ° C. and 80% RH to obtain solid materials of zinc stearate (surface energy reducing agents A to F) having different moisture contents as shown in Table 3. These water contents A to F were prepared by changing the drying time at 110 ° C.
[0185]
[Table 3]

[0186]
Example 1
<Evaluation>
In each of the examples and comparative examples, each of the developing units of Y (yellow), M (magenta), C (cyan), and Bk (black) is used by using the photosensitive member and developer group (toner group) shown in Table 2. 1 is mounted on the digital copying machine having the intermediate transfer member shown in FIG. 1, and the original image has a white background, Bk, Y, M, and C solid (solid) image portions, character image portions, and halftone images. An A4 image having a thickness of 10,000 was printed and evaluated under normal temperature and normal humidity (20 ° C., 50% RH). Evaluation items, evaluation methods, and evaluation criteria are described below.
[0187]
Character chile
A character image was formed, and toner dust around the character was observed visually and with a 20-fold magnifier, and evaluated according to the following criteria.
[0188]
A: Toner dust around the characters is not observed even with loupe observation (good)
○: Cannot be visually discerned, but toner dust around the characters is observed with a loupe (no problem in practice)
×: Toner dust around the character is visually observed, and the sharpness of the character is inferior (practically problematic)
Transcription missing
Transfer a halftone image with a density of 0.4 to a transfer paper (basis weight 200 g / m ² ) And the occurrence of white spots due to missing transfer was visually evaluated.
[0189]
◎◎: No transfer at all (very good)
A: 1 to 2 transfer omissions exist only on the back surface per 100 images, but it cannot be distinguished without staring (good)
○: Although there are 1 to 4 transfer omissions per 50 images, it cannot be determined without staring (no problem in practical use)
×: 5 or more clear transfer omissions exist for 50 images regardless of the front and back sides (practical problem)
Black spot
In the halftone image, the periodicity coincided with the cycle of the photosensitive member, and it was determined how many black spots (saddle-shaped spot images) per A4 size.
[0190]
A: Occurrence frequency of black spots of 0.4 mm or more: All copy images are 3 / A4 or less (good)
○: Occurrence frequency of black spots of 0.4 mm or more: 1 or more of 4 / A4 or more and 15 / A4 or less (no problem in practical use)
X: Occurrence frequency of black spots of 0.4 mm or more: 1 or more of 16 / A4 or more (practical problem)
Image density
The image density was measured by using a densitometer “RD-918” (manufactured by Macbeth Co., Ltd.) for the solid portion of each color and measuring the relative reflection density with zero recording paper.
[0191]
A: Each density of a solid (solid) image portion of Bk and Y, M, and C is 1.2 or more (good)
○: Each density of Bk and Y, M, C solid (solid) image part is 0.8 or more (no problem in practical use)
X: Each density of the solid (solid) image portion of Bk and Y, M, and C is less than 0.8 (practical problem)
(Sharpness)
The sharpness of the image was evaluated by squeezing the characters in both low temperature and low humidity (10 ° C., 20% RH) and high temperature, high humidity (30 ° C., 80% RH) environments. 3-point and 5-point character images were formed and evaluated according to the following criteria.
[0192]
◎: 3 points and 5 points are clear and easy to read
○: 3 points are partially unreadable, 5 points are clear and easily readable
×: 3 points are almost unreadable 5 points are partially or completely unreadable
Process conditions for digital copiers with intermediate transfer members.
Image formation line speed L / S: 180 mm / s
Charging condition of the photoconductor (60 mmφ): The potential of the non-image part is detected by a potential sensor and can be feedback controlled. The controllable range is −500 V to −900 V, and the surface of the photoconductor when fully exposed The potential was in the range of −50 to 0V.
[0193]
Image exposure light: Semiconductor laser (wavelength: 780 nm)
Intermediate transfer body: A seamless endless belt-like intermediate transfer body 70 is used, and a volume resistivity is 1 × 10 with a semiconductive resin belt. ⁸ The one with Ω · cm and Rz of 0.9 μm was used.
[0194]
Primary transfer conditions
Primary transfer roller (5Y, 5M, 5C, 5Bk (6.05 mmφ in FIG. 1)): Configuration in which elastic rubber is attached to the core metal: Surface resistivity 1 × 10 ⁶ Ω, transfer voltage applied
Secondary transfer conditions
An endless belt-like intermediate transfer body 70 as an intermediate transfer body and a backup roller 74 and a secondary transfer roller 5A are arranged so as to sandwich the endless belt-like intermediate transfer body 70, and the resistance value of the backup roller 74 is 1 × 10. ⁶ Ω, and the resistance value of the secondary transfer roller as the secondary transfer means is 1 × 10 ⁶ Ω and constant current control (about 80 μA) is performed.
[0195]
Fixing is a thermal fixing method using a fixing roller in which a heater is disposed inside the roller.
The distance Y on the intermediate transfer member from the first contact point between the intermediate transfer member and the photosensitive member to the first contact point with the next color photosensitive member was set to 95 mm.
[0196]
The outer peripheral length (circumferential length) of the drive roller 71, the guide rollers 72 and 73 and the backup roller 74 for secondary transfer is 31.67 mm (= 95 mm / 3), and the outer peripheral length of the tension roller 76 is 23. .75 mm (= 95 mm / 4).
[0197]
The outer peripheral length of the primary transfer roller was 19 mm (= 95 mm / 5).
Photoconductor cleaning conditions
Cleaning blade: A urethane rubber blade was brought into contact with the photoconductor rotating direction in a counter manner.
[0198]
Intermediate transfer member cleaning conditions
Cleaning blade: A urethane rubber blade was brought into contact with the intermediate transfer member in the counter direction.
[0199]
The results are shown in Table 4.
[0200]
[Table 4]

[0201]
From Table 4 above, a combination of a photoreceptor satisfying the requirements of the present invention (surface contact angle with water of 90 ° or more) and the developer group of the developing means, that is, each color toner has a turbidity of less than 60, and each color toner Maximum turbidity difference between 10-3 No. 5 developer group combination (No. 4 ~ 8, 10-1 1 , 14 ~ 19 , 22, 23, 25, 26, 28, 29) have achieved good evaluations over the practical range in terms of character dust, omission of transfer, black spots, image density, and sharpness. In the combination using the agent group (No. 1, 9, 13, 21, 24, 27, 30), the turbidity difference between the color toners was 4.1. In No. 1, the fluidity of the toner was insufficient, transfer omission, image density and sharpness were lowered, and the turbidity difference was 47 units. 13, no. At 30, the balance of charge amount is unstable, so that there are many character dust (colored character dust) and sharpness is lowered. No. At 30, transfer omission also occurs. In addition, in the developer group (No. 21, No. 24, No. 27) in which any turbidity of each color toner is 60 or more, there are excessive free external additives, black spots occur frequently, and sharpness decreases. ing. Further, in the combination (No. 9) using a photoconductor having a contact angle with water of 84 ° on the surface, transfer omission occurs and sharpness deteriorates. Further, among the combinations satisfying the requirements of the present invention, the turbidity difference between each color toner in the developer group and the photosensitive member having a contact angle with water of 95 ° or more on the surface is a maximum of 10 to 35 and the turbidity of the black toner The developer group (No. 4, 5, 6, 7, 10, 11, 14, 15, 16, 18, 29) having a degree of less than 20 has a remarkable improvement effect.
[0202]
Example 2 (Example in which a photoreceptor 1 is used and a surface energy reducing agent is supplied)
The cleaning device of the image forming apparatus unit of the digital copying machine having the intermediate transfer member of the first embodiment is changed to cleaning means having a brush roll that also serves as the agent applying means shown in FIG. While the zinc was placed at 66K in FIG. 5 and zinc stearate was supplied to the surface of the photoconductor via a brush roll, the photoconductor, surface energy reducing agent and developer group shown in Table 5 as in Example 1 ( The image forming unit combined with (toner group) (combination No. 31 to 60) was evaluated for incorporation in a digital copying machine having an intermediate transfer member. Evaluation items, evaluation methods, and evaluation criteria were the same as in Example 1.
[0203]
Cleaning conditions of the cleaning means having the agent applying means of FIG.
Cleaning blade: A urethane rubber blade was brought into contact with the photoconductor rotating direction in a counter manner.
[0204]
Cleaning brush: conductive acrylic resin, brush hair density (3 × 10 ^Three / Cm ² ), The amount of biting was set to 1.0 mm.
[0205]
[Table 5]

[0206]
Evaluation was performed under the above conditions. As a result, almost the same evaluation results as in Example 1 were obtained. That is, even if the surface layer of the photoconductor does not contain fluorine-based resin particles, the surface energy reducing agent is supplied to the surface of the photoconductor, and the contact angle with water on the surface of the photoconductor is set to 90 ° or more. The same effect as in Example 1 was obtained.
[0207]
Example 3 (example in which the toner particle size distribution is changed)
(Production of toners 7Bk, 7Y, 7M, and 7C)
In the toner production of the toners 2Bk, 2Yb, 2M, and 2C, M (m ₁ + M ₂ The toners 7Bk, 7Y, 7M, and 7C were prepared in the same manner except that, and the like were changed. Number average particle diameters of toners 7Bk, 7Y, 7M, and 7C, M (m ₁ + M ₂ ) And toner turbidity are shown in Table 6.
[0208]
By mixing 10 parts by weight of each of these toners and 100 parts by weight of 45 μm ferrite carrier coated with a styrene-methacrylate copolymer, developer 22 for evaluation is made as developer 7Bk, 7Y, 7M, 7C. Groups were made.
(Production of toners 8Bk, 8Y, 8M, 8C)
In the toner production of the toners 2Bk, 2Yb, 2M, and 2C, M (m ₁ + M ₂ The toners 8Bk, 8Y, 8M, and 8C were prepared in the same manner except that, and the like were changed. Number average particle diameters of toners 8Bk, 8Y, 8M, and 8C, M (m ₁ + M ₂ ) And toner turbidity are shown in Table 6.
[0209]
By mixing 10 parts by mass of each toner of these toners and 100 parts by mass of 45 μm ferrite carrier coated with a styrene-methacrylate copolymer, developer 23 for evaluation 8Bk, 8Y, 8M and 8C was prepared. Groups were made.
[0210]
[Table 6]

[0211]
Combination No. 1 of Example 1 Evaluation was performed in the same manner as in Example 1 except that the developer 22 group and the 23 group were used instead of the 4 developer 4 groups (toners 2Bk, 2Yb, 2M, and 2C). The results are shown in Table 7.
[0212]
[Table 7]

[0213]
From Table 7, the developer group 22 having a sum (M) of the relative frequencies of the toner particles of 70% or more is superior to the developer group 23 in which (M) is less than 70%, and the improvement degree of the evaluation items is excellent. It can be seen that
[0214]
【The invention's effect】
By using the present invention, it is possible to achieve improvement in toner transfer characteristics of an electrophotographic system using an intermediate transfer member, to prevent image defects such as omission of transfer and character dust generated due to a decrease in toner transfer, and image density and An electrophotographic image forming apparatus and an image forming method capable of forming a color image with excellent sharpness can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.
FIG. 2 illustrates an example of an intermediate transfer member cleaning unit.
FIG. 3 is a layout diagram showing a positional relationship among a photosensitive member, an endless belt-shaped intermediate transfer member, and a primary transfer roller.
FIG. 4 is a layout diagram showing a positional relationship among a backup roller, an endless belt-shaped intermediate transfer member, and a secondary transfer roller.
FIG. 5 is a configuration diagram of a cleaning unit installed in the image forming unit of the present invention.
[Explanation of symbols]
1Y, 1M, 1C, 1Bk photoconductor
2Y, 2M, 2C, 2Bk charging means
3Y, 3M, 3C, 3Bk exposure means
4Y, 4M, 4C, 4Bk developing means
5A Secondary transfer roller (secondary transfer means)
5Y, 5M, 5C, 5Bk Primary transfer roller (primary transfer means)
6A, 6Y, 6M, 6C, 6Bk Cleaning means
7 Endless belt-like intermediate transfer unit
10Y, 10M, 10C, 10Bk Image forming unit (image forming unit)
61 blade
62 Bracket
63 Spindle
70 Endless belt-shaped intermediate transfer member

Claims (6)

A plurality of image forming units each having an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are provided, and an electrophotographic photosensitive member using toner having a different hue for each of the plurality of image forming units. A primary transfer means for forming a toner image thereon, sequentially transferring the formed toner image on the intermediate transfer member from the electrophotographic photosensitive member, and forming a color toner image on the intermediate transfer member; In an image forming method using an image forming apparatus having a secondary transfer unit for transferring a color toner image on an intermediate transfer member to a recording material, an additive amount of each color toner used in a developing unit of the plurality of image forming units is but constant, with turbidity less than 60 for each color toner as defined below, the toner of the maximum turbidity of the respective color toners are yellow toner, up to 1 difference in turbidity between the color toner It is 35, and an image forming method having a contact angle with water of the surface of the electrophotographic photosensitive member is characterized in that at least 90 °. Toner turbidity: HAZE value = defined as a percentage of diffuse component / total transmitted component. Method for measuring turbidity of toner: 5.0 g of toner is dispersed in 50 ml of an aqueous solution containing 1 ml of a surfactant (detergency family; manufactured by Kao Corporation) and separated using a centrifuge (2000 rpm: 10 minutes). . Since the toner component precipitates, a supernatant liquid which is a free component is collected. Using this, COH-300A manufactured by Nippon Denshoku Co., Ltd., the HAZE value (percentage: where% is omitted) calculated from the ratio of the diffuse component of the total transmitted component to the incident light is used as the turbidity of the toner. . 2. The image forming method according to claim 1, wherein the surface layer of at least one electrophotographic photosensitive member of the plurality of image forming units contains fluorine-based resin particles. The image forming method according to claim 1, wherein at least one of the plurality of image forming units has an agent applying unit that supplies a surface energy reducing agent to the surface of the electrophotographic photosensitive member. When the particle size distribution of each color toner used for the developing means of the plurality of image forming units is D (μm), the natural logarithm lnD is taken on the horizontal axis, and a plurality of the horizontal axes are arranged at intervals of 0.23. In the histogram showing the number-based particle size distribution divided into classes, the relative frequency (m ₁ ) of the toner particles contained in the most frequent class and the relativeness of the toner particles contained in the next most frequent class after the most frequent class The image forming method according to claim 1, wherein the sum (M) of the frequency (m ₂ ) is 70% or more. A plurality of image forming units are four image forming units, an image forming unit having black toner, an image forming unit having yellow toner, an image forming unit having magenta toner, and an image forming having cyan toner The image forming method according to claim 1, comprising a unit. The image forming method according to claim 1, wherein the black toner has a toner turbidity of less than 20. 6.

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