JP2004133284A - Method for transfer, method and apparatus for image forming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrences of a transfer toner scattering and transfer void which causes problems at the time of electrostatically transferring a toner image from an intermediate transfer body to a transfer material. <P>SOLUTION: The toner image transferred from an image carrier to an intermediate transfer belt 51 is electrostatically transferred to transfer paper P by using a transfer roller 56 by a transfer method. The surface layer of the surface of the intermediate transfer belt 51 where toner is stuck possesses an elastic layer, and a means 56d to apply pressure between the transfer roller 56 and the intermediate transfer belt 51 is provided, and a transfer bias current between the intermediate transfer belt 51 and the transfer roller 56 is set as 0.05-0.2μA/cm, and the pressure of 1-10N/cm is applied between the transfer roller 56 and the backup roller 55 of the intermediate transfer belt 51. Thus, a transfer electric field is applied without depending on a toner level, so that the electrified amount of transfer paper is suppressed small, and discharge at a separating time is reduced and the transfer toner scattering can be reduced. <P>COPYRIGHT: (C)2004,JPO

Description

【００４３】
表１の結果より、上記の中間転写ベルトを用いて、圧力は１．０〜５．０Ｎ／ｃｍ、転写電流は０．０５〜０．２０μＡ／ｃｍの範囲が転写率、転写チリ、転写白抜けで良好な範囲であった。転写電流を大きくすると転写紙のリーク現象が発生し、トナー逆電荷が注入され、転写率が低下傾向にある。また、転写電流が小さすぎると、転写紙に吸引する力（前述の式（１）のＦ）が小さくなり転写しなくなる。転写圧力に関しては、圧力が０．０５Ｎ／ｃｍと小さいと転写紙と中間転写ベルトの密着が弱く、転写率が低下し、転写チリが発生しやすくなる。一方、圧力を大きくして１０．０Ｎ／ｃｍにすると、圧力が強すぎ、転写でトナー層が大きい場合、中間転写ベルトに付着しやすく、また崩れやすくなり、結果として良好なデータが得られなかった。
また、用いた中間転写ベルトの表面特性は、アスカーＣ硬度で１５度未満は軟らかすぎて、トナーが中間転写ベルト上に残ってしまう。また、硬度が４０度を大きく越えると硬すぎてトナーのＺ軸方向のトナー食い込みが少なくエアーギャップの低減化にならない。
さらに、中間転写ベルト上の軟弾性層の厚みは０．１ｍｍ未満では、コートムラが大きく十分なトナー食い込みが得られない。また、０．２ｍｍを越えてしまうと、圧力が大きい場合と同じく、トナーが中間転写ベルトに付着しやすく、また崩れやすくなり、結果として良好なデータ得られなかった。
【００４４】
［実施例２］
実施例１と同様の方式で　、中間転写ベルトの弾性層上の表面にフッ素系樹脂のコーティング処理を行う際に、以下の３水準の処方でスプレーコートし、熱乾燥して、３種類の中間転写ベルトを作成した。
【００４５】
＜コーティング処理処方１＞
・フッ素系樹脂（ルミフロン６０１Ｃ；旭硝子）：１００重量部
・ルミフロン用硬化剤：２０重量部
・窒化ホウ素：２０重量部
＜コーティング処理処方２＞
・処方１の材料：１４０重量部
・フッ素微粉末（１μｍ）：５重量部
＜コーティング処理処方３＞
・処方１の材料：１４０重量部
・フッ素微粉末（１μｍ）：１０重量部
【００４６】
以上の処方をメチルイソブチルケトン２００部、キシレン１００部に混ぜボールミルで約６０時間ミリングして、スプレーコートして作成した。
処方１のコーティング処理を施した中間転写ベルトの摩擦係数は０．２２、処方２のコーティング処理を施した中間転写ベルトは摩擦係数０．６８、処方３のコーティング処理を施した中間転写ベルトの摩擦係数は０．９６であった。
【００４７】
この３種類の中間転写ベルトを用い、実施例１と同様の装置構成及び方法で画像サンプルを得た。
尚、中間転写ベルトの支持体の表面層には、硬度１５〜４０度（ＡｓｋｅｒＣ／１ｋｇ荷重時）、厚みで０．１〜０．２ｍｍのシリコーン弾性層を設けた。そして、その上に上記のフッ素系樹脂のコート層を設けた。転写圧は３．２Ｎ／ｃｍ、転写電流は０．１５μＡ／ｃｍの条件を用いた。
以下の表２に、転写チリ（図６の評価ランク参照）、転写白抜け（図７の評価ランク参照）の評価を行った結果を示す。
【００４８】
【表２】

【００４９】
以上の結果より、中間転写ベルトの表面層の摩擦係数は０．７以下が良好な条件となる。摩擦係数が小さければ、トナーと転写紙と中間転写ベルトに転写圧が加わって、トナー同士が付着しても、中間転写ベルトには付着せず、転写分離後のトナーは転写紙上に移動する。一方、摩擦係数が高すぎる、トナーと中間転写ベルトの接着力が大きくなり、転写分離でトナーと中間転写ベルトは付着しやすくなり、特に付着量の多い太めの文字部の中央部などが中間転写ベルトに付着したまま残り、転写白抜けとなり、異常画像となる。
【００５０】
［実施例３］
次に現像に用いるトナーの処方を変えて作成したトナーの特性と、転写特性の実施例を示す。
＜トナー処方１＞
・ポリエステル樹脂（重量平均分子量：３１００００、Ｔｇ：６５℃）：４４重量部
・スチレン−ｎ−ブチルアクリレート共重合体（重量平均分子量：８５０００、Ｔｇ：６８℃）：４０重量部
・カルナウバワックス：５重量部
・カーボンブラック（＃４４：三菱化学）：１０重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：１重量部
【００５１】
以上の処方で２軸エクストルーダーを用いて１３０℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径８．５μｍとした後、ヘンシェルミキサーを用いてシリカ（Ｒ−９７２　日本アエロジル）０．５重量％を混合し、トナーを得た。このトナーの硬度は８、凝集度は３０％、体積固有抵抗は８．５×１０^８Ωｃｍであった。
【００５２】
＜トナー処方２＞
・ポリエステル樹脂（重量平均分子量：１８５０００、Ｔｇ：６７℃）：７１重量部
・カルナウバワックス（平均粒径：３００μｍ）：３重量部
・四三酸化鉄（ＥＰＴ−１０００：戸田工業）：１５重量部
・カーボンブラック（＃４４：三菱化学）：１０重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：１重量部
【００５３】
以上の処方で２軸エクストルーダーを用いて１６０℃で混練後、機械式粉砕機により粉砕、分級し重量平均粒径５．５μｍとした後ヘンシェルミキサーを用い、シリカ（Ｒ−９７２　日本アエロジル）１．０重量％を混合しトナーを得た。このトナーの硬度は１１、凝集度は８．０％、体積固有抵抗は５．５×１０^８Ωｃｍであった。
【００５４】
＜トナー処方３＞
・スチレン／ｎ−ブチルメタクリレート／２−エチルヘキシルアクリレート共重合体（組成比：７５／１０／１５　重量平均分子量：２１００００　Ｔｇ：５７℃）：５５重量部
・ポリエステル樹脂（重量平均分子量：１６００００　Ｔｇ：６４℃）：２３重量部
・ポリエチレンワックス（分子量９００）：１０重量部
・カーボンブラック（＃４４：三菱化学）：１０重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：２重量部
【００５５】
以上の処方で２軸エクストルーダーを用いて９０℃で混練後、気流式粉砕機により粉砕、分級して重量平均粒径７．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）０．２重量％を混合し、トナーを得た。このトナーの硬度は６、凝集度は５５．０％、体積固有抵抗は８．８×１０^８Ωｃｍであった。
【００５６】
＜トナー処方４＞
・ポリエステル樹脂（重量平均分子量：２７４０００、Ｔｇ：６８℃）：７９重量部
・ポリエチレンワックス（分子量９００）：３重量部
・カーボンブラック（＃４４：三菱化学）：１５重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：３重量部
【００５７】
以上の処方で２軸エクストルーダーを用いて１５０℃で混練後、気流式粉砕機により粉砕、分級して重量平均粒径９．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）１．０重量％を混合し、トナーを得た。このトナーの硬度は１４、凝集度は８．５％、体積固有抵抗は４．２×１０^８Ωｃｍであった。
【００５８】
＜トナー処方５＞
・ポリエステル樹脂（重量平均分子量：３１００００、Ｔｇ：６５℃）：４９重量部
・スチレン−ｎ−ブチルアクリレート共重合体（重量平均分子量：８５０００、Ｔｇ：６８℃）：３５重量部
・カルナウバワックス：４重量部
・カーボンブラック（＃４４：三菱化学）：１０重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：２重量部
【００５９】
以上の処方で２軸エクストルーダーを用いて１３０℃で混練後、機械式粉砕機により粉砕、分級して重量平均粒径８．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）０．５重量％を混合し、トナーを得た。このトナーの硬度は１０、凝集度は２０％、体積固有抵抗は９．５×１０^８Ωｃｍであった。
【００６０】
＜トナー処方６＞
・ポリエステル樹脂（重量平均分子量：１８５０００、Ｔｇ：６７℃）：７３重量部
・カルナウバワックス（平均粒径：３００μｍ）：５重量部
・四三酸化鉄（ＥＰＴ−１０００：戸田工業）：１０重量部
・カーボンブラック（＃４４：三菱化学）：１０重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：２重量部
【００６１】
以上の処方で２軸エクストルーダーを用いて１６０℃で混練後、機械式粉砕機により粉砕、分級して重量平均粒径６．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）０．７５重量％混合し、トナーを得た。このトナーの硬度は１１、凝集度は３１％、体積固有抵抗は９．８×１０^８Ωｃｍであった。
【００６２】
＜トナー処方７＞
・ポリエステル樹脂（重量平均分子量：３１００００、Ｔｇ：６５℃）：５６重量部
・スチレン−ｎ−ブチルアクリレート共重合体（重量平均分子量：８５０００、Ｔｇ：６８℃）：３５重量部
・カルナウバワックス：３重量部
・カーボンブラック（＃４４：三菱化学）：５重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：１重量部
【００６３】
以上の処方で２軸エクストルーダーを用いて８０℃で低温混練後、機械式粉砕機により粉砕、分級して重量平均粒径８．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）０．５重量％を混合し、トナーを得た。このトナーの硬度は１０、凝集度は１５％、体積固有抵抗は３．５×１０^９Ωｃｍであった。
【００６４】
＜トナー処方８＞
・ポリエステル樹脂（重量平均分子量：３１００００、Ｔｇ：６５℃）：５６重量部
・スチレン−ｎ−ブチルアクリレート共重合体（重量平均分子量：８５０００、Ｔｇ：６８℃）：３５重量部
・カルナウバワックス：３重量部
・カーボンブラック（＃４４：三菱化学）：５重量部
・荷電制御剤（スピロンブラックＴＲ−Ｈ：保土ヶ谷化学）：１重量部
【００６５】
以上の処方で２軸エクストルーダーを用いて８０℃で低温混練後、機械式粉砕機により粉砕、分級して重量平均粒径８．５μｍとした後、ヘンシェルミキサーを用いて、シリカ（Ｒ−９７２　日本アエロジル）１．０重量％とステアリン酸亜鉛微粉末０．２０重量部を混合し、トナーを得た。このトナーの硬度は１０、凝集度は３５．０％、体積固有抵抗は１．８×１０^９Ωｃｍであった。
【００６６】
以上の処方１〜８で作成したトナーを用い、実施例２と同じ条件で転写特性の評価を行った。また、中間転写ベルトとしては、表面摩擦係数が０．６８の中間転写ベルトを用いた。
評価項目としては、転写チリ（図６のランク見本参照）と転写白抜け（図７のランク見本参照）を評価し、両項目で良好な条件を選んだ。評価結果を下記の表３に示す。
【００６７】
【表３】

【００６８】
以上の評価データより、トナーの硬度で８〜１１、凝集度で１５〜３５％のトナーが、転写での画像でバランスの良いトナー特性を示している。
この結果より、トナーの凝集度は１５〜４０％、より好ましくは１５〜３５％である。トナー凝集度が１５％以下の場合は、トナーの流動性が良すぎて、転写の際にチリが発生しやすくなる。また、トナー凝集度が４０％以上の場合は、トナーの凝集力が強くなり、転写性が悪くなる。また、転写白抜けが発生する。
【００６９】
トナー硬度は７〜１２、より好ましくは８〜１１である。トナー硬度が７以下の場合は、トナー粒子同士が接した場合、塑性変形するため、トナー同士の接触面積が増加し、トナーの凝集力が強くなり、トナー層と中間転写ベルトが付着しやすく、転写白抜けがでやすい。また、トナー硬度が１２以上の場合は、転写工程での問題はないが、定着工程において定着性が悪化する恐れがある。
【００７０】
【発明の効果】
以上説明したように、本発明の転写方法では、中間転写体（例えば中間転写ベルト）のトナーの付着した面の表層に弾性層を設け、転写手段（転写ローラまたは転写ベルト）と中間転写ベルトの間に圧力を加える手段を設け、中間転写ベルトと転写手段間の転写バイアス電流が０．０５〜０．２μＡ／ｃｍとなるようにしており（請求項１）、さらには、前記転写手段と前記中間転写ベルトのバックアップローラ間に１〜１０Ｎ／ｃｍの圧力を加えることを特徴としているので（請求項２）、これによりトナー高さに依存せず転写電界を印加することができるので、転写紙の帯電量は少なく抑えられ、分離時の放電を低減することができ、転写チリを減少できる。したがって、中間転写ベルトから転写紙に静電転写する工程で転写チリの少ないシャープな画像を得ることができる。
【００７１】
また、本発明の転写方法では、前記中間転写ベルトは支持体上に１層以上の弾性層を有し、最表面層に０．１〜０．２ｍｍの厚みで、硬度が１５〜４０度の弾性層を有する構成としているので（請求項３）、中間転写ベルトと転写紙間に圧力を加えることにより、トナーが表面軟弾性層に食い込み、トナーと転写紙は密着が良くなる。その結果、転写紙の帯電量は少なく抑えられ、分離時の放電を低減することができ、転写チリを減少できる。したがって、中間転写ベルトから転写紙に静電転写する工程で転写チリの少ないシャープな画像を得ることができる。尚、中間転写ベルトの弾性層が厚すぎるとトナー層がズレを起こすことになるので、本発明では、最表面層は０．１〜０．２ｍｍの厚みとし、最適厚みとなるようにしている。
【００７２】
さらに本発明の転写方法では、前記中間転写ベルトの弾性層上に表面処理を行い、中間転写ベルトの表面層の摩擦係数を０．７以下になるように処理しているので（請求項４）、トナー同士が付着した場合にも転写紙側に付着して白抜けを防止することができる。したがって、中間転写ベルトの表面の摩擦係数を０．７以下に処理することによって、転写チリが少なく、転写白抜けが少ない画像を得ることができる。
【００７３】
本発明の画像形成方法及び装置では、請求項１〜４のいずれかに記載の転写方法を用い、さらには、現像に用いるトナーとして、凝集度が１５〜４０％のトナーを用いることを特徴としており（請求項５，６，８）、トナー凝集度を１５〜４０％と最適にすることにより、転写チリが少なく、転写白抜けが少ない画像を得ることができる。
また、本発明の画像形成方法及び装置では、請求項１〜４のいずれかに記載の転写方法を用い、さらには、現像に用いるトナーとして、硬度が７〜１２度のトナーを用いることを特徴としており（請求項５，７，８）、トナーの硬度を７〜１２度と最適にすることにより、転写チリが少なく、転写白抜けが少ない画像を得ることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す画像形成装置の概略構成図である。
【図２】中間転写ベルトから転写紙へトナー画像を転写する際の転写チリの発生メカニズムの説明図である。
【図３】中間転写ベルトから転写紙へトナー画像を転写する第二転写部の構成例を示す概略要部構成図である。
【図４】中間転写ベルトから転写紙へトナー画像を転写する際に、従来の支持体のみからなる中間転写ベルトを用いた場合の転写紙転写モデルを示す図である。
【図５】中間転写ベルトから転写紙へトナー画像を転写する際に、本発明の中間転写ベルトを用いた場合の転写紙転写モデルを示す図である。
【図６】転写チリの評価ランク見本を示す図である。
【図７】転写白抜けの評価ランク見本を示す図である。
【符号の説明】
１　　　感光体（像担持体）
２　　　帯電器（帯電手段）
３　　　露光手段（潜像形成手段）
４　　　回転型現像装置（現像手段）
５　　　中間転写ベルト装置（中間転写手段）
６　　　クリーニング装置（クリーニング手段）
７　　　定着装置（定着手段）
３２　　露光装置
３３　　折返しミラー
３４　　レーザ光
４１　　イエロー現像器
４２　　マゼンタ現像器
４３　　シアン現像器
４４　　ブラック現像器
５１　　中間転写ベルト（中間転写体）
５２　　中間転写ローラ
５５　　バックアップローラ
５６　　転写紙転写ローラ（転写紙転写手段）
５７　　搬送ベルト
６１　　クリーニングブレード
６２　　クリーニングブラシ
７１　　定着ローラ
７２　　加圧ローラ
１０１　給紙バンク
１０２　給紙ローラ
１０３　搬送ローラ
１０４　レジストローラ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic image forming method and an image forming apparatus such as a copying machine, a printer, a plotter, and a facsimile using the image forming method, and more particularly, to an image carrier using an intermediate transfer member. The present invention relates to a transfer method characterized in transferring a toner image from an intermediate transfer member to an intermediate transfer member and a transfer of a toner image from the intermediate transfer member to a transfer material, and an image forming method and an image forming apparatus using the transfer method.
[0002]
[Prior art]
In recent years, high image quality has been demanded also in an electrophotographic color image forming method, which has been improved by reducing the diameter of toner, improving development, and the like. However, when observed at each image forming step, it is clear that the latent image, the development, the intermediate transfer, the transfer paper transfer, and the fixing are deteriorated in each step. In particular, the deterioration in the transfer step is large. As a phenomenon, generation of dust due to discharge at the time of pre-transfer at the time of transfer entry and at the time of peeling after transfer is a major problem.
Many proposals have been made for these issues. For example, in Japanese Patent Application Laid-Open No. H11-216, there is provided a pressing roller that presses the intermediate transfer belt from the inner peripheral surface toward the photosensitive drum at least in a contact area of the intermediate transfer belt with the photosensitive drum in a lateral direction of the belt. To improve the adhesion between the transfer belt and the intermediate transfer belt, increase the cohesion of the toner at the contact nip, and prevent partial transfer failure and transfer dust due to insufficient adhesion between the photosensitive drum and the intermediate transfer belt. Have been.
[0003]
Further, in the following Patent Document 2, in the color image forming method, in order to solve the transfer dust and bug-like transfer failure in the transfer from the photoreceptor to the intermediate transfer member, a contact pressure of 15 g / cm or more is used as a transfer process. A pressing force is applied to set the linear speed ratio between the intermediate transfer belt and the photoconductor to 0.85 to 1.10, and surface / volume resistance and the like are defined as the characteristics of the intermediate transfer belt. It has been proposed to regulate the adhesion between toners, the transfer gap, the charge retention of the intermediate transfer belt, and the like, by defining the particle size.
[0004]
[Patent Document 1]
JP 2000-22188 A
[Patent Document 2]
JP 2001-209255 A
[0005]
[Problems to be solved by the invention]
In recent years, image quality has been further improved, and polymerized toner has been used as toner. As the toner characteristics, characteristics such as further reduction in diameter, spheroidization, uniform shape, uniform charge amount, and the like are easily obtained, which leads to improvement in image quality.
In the above-described conventional example, when the polymerized toner is used, the transfer dust is large, and although there is apparently smoothness, the image is poor in sharpness and lacks sharpness, and it is difficult to read fine characters. I have.
In particular, as a characteristic of a color image, toners of different heights in the Z-axis direction (direction perpendicular to the belt surface) of one to three colors adhere to the intermediate transfer belt. For this reason, depending on the thickness of the toner layer, a portion where the toner is in close contact with the transfer paper and a portion where the toner exists with a gap appear. As a result, the electric field around the toner in the portion having the void becomes smaller than that in the portion having a large amount of the toner (the dielectric constant of the toner layer is about 3 while the dielectric constant of the void is 1; The electric field of the air gap for the layer is equivalent to 1/3). As a result, it is necessary to increase the electric field required for transfer, and the amount of charge on the transfer paper due to the transfer bias increases. Then, a discharge phenomenon easily occurs at the time of separation, and transfer dust increases.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to use an intermediate transfer member having a surface elastic layer, apply transfer pressure during transfer from the intermediate transfer member to a transfer material, and apply air pressure. To provide a transfer method capable of reducing a gap, applying a minimum transfer bias to maintain a sufficient transfer electric field for transfer, and preventing transfer dust due to discharge during transfer separation, and Provided is an image forming method capable of obtaining an image with less transfer dust, sharpness, and less transfer whiteout in a step of electrostatically transferring an intermediate transfer body to a transfer material by using a transfer method, and furthermore, forming the image. Image forming apparatus capable of providing an optimal toner characteristic for use in the method and obtaining an image with less transfer dust, sharpness, and less transfer white spots by using the above image forming method. It is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a transfer method for electrostatically transferring a toner image transferred from an image carrier to an intermediate transfer member to a transfer material using a transfer unit. An elastic layer is provided on the surface of the transfer member to which the toner adheres, and a unit for applying pressure between the transfer unit and the intermediate transfer unit is provided. A transfer bias current between the intermediate transfer unit and the transfer unit is reduced. It is characterized by being 0.05 to 0.2 μA / cm.
According to a second aspect of the present invention, in the transfer method according to the first aspect, the intermediate transfer body is an intermediate transfer belt supported by a plurality of rollers, and the transfer unit is a transfer roller or a transfer supported by the rollers. A belt, wherein a pressure of 1 to 10 N / cm is applied between the transfer unit and a backup roller of the intermediate transfer belt.
Further, according to a third aspect of the present invention, in the transfer method according to the first or second aspect, the intermediate transfer member has at least one elastic layer on a support, and the outermost surface layer has 0.1 to 0. It is characterized by having an elastic layer having a thickness of 2 mm and a hardness of 15 to 40 degrees.
According to a fourth aspect of the present invention, in the transfer method according to the first, second or third aspect, a surface treatment is performed on the elastic layer of the intermediate transfer body to reduce the friction coefficient of the surface layer of the intermediate transfer body to zero. .7 or less.
[0008]
The invention according to claim 5 includes one or more steps of forming a latent image on an image carrier, developing the latent image with toner to form a toner image, and transferring the toner image to an intermediate transfer member. And transferring the toner image of one or more colors onto the intermediate transfer member, and then electrostatically transferring the toner image transferred to the intermediate transfer member to a transfer material using a transfer unit. An image forming method for forming an image by fixing a toner image transferred onto a material, wherein the transfer method according to any one of claims 1 to 4 is used.
According to a sixth aspect of the present invention, in the image forming method according to the fifth aspect, a toner having a cohesion degree of 15 to 40% is used as a toner used for development.
According to a seventh aspect of the present invention, in the image forming method according to the fifth aspect, a toner having a hardness of 7 to 12 degrees is used as a toner used for development.
[0009]
The invention according to claim 8 provides a latent image forming means for forming a latent image on the image carrier, a developing means for developing the latent image with toner to form a toner image, and a method for transferring the toner image to an intermediate transfer member. An image including an intermediate transfer unit for transferring, a transfer unit for electrostatically transferring the toner image transferred to the intermediate transfer body to a transfer material, and a fixing unit for fixing the toner image transferred on the transfer material In a forming apparatus, the image forming method according to any one of claims 5 to 7 is used.
[0010]
Hereinafter, the present invention will be described in more detail.
A toner image transferred from an image carrier (for example, a photoconductor) to an intermediate transfer body (for example, an intermediate transfer belt) is electrostatically transferred to a transfer material (for example, transfer paper) using a transfer unit (a transfer roller or a transfer belt). In the transfer method for transferring, the electrostatic transfer from the intermediate transfer belt to the transfer paper is moved by the electric field around the toner and the charge amount of the toner. However, when a sufficient transfer electric field is applied, the charge amount of the transfer paper increases, and a discharge phenomenon occurs during transfer separation, resulting in toner transfer dust. In particular, in the case of a color image formed by superposing a plurality of toners, if there is a difference in the height of the toner layer on the intermediate transfer belt in the Z-axis direction (direction perpendicular to the belt surface), the transfer efficiency naturally becomes a condition. In this case, a transfer bias is applied in accordance with the worse one. As a result, the transfer paper is excessively charged, and discharge occurs during transfer separation, resulting in transfer dust.
Therefore, in the transfer method of the present invention, an elastic layer is provided on the surface layer of the intermediate transfer belt to which the toner is attached, and a means for applying pressure between a transfer unit (transfer roller or transfer belt) and the intermediate transfer belt is provided. The transfer bias current between the belt and the transfer means is adjusted to 0.05 to 0.2 μA / cm (Claim 1), and further, 1 to 10 N is applied between the transfer means and the backup roller of the intermediate transfer belt. / Cm is applied (claim 2), whereby the transfer electric field can be applied irrespective of the height of the toner, so that the charge amount of the transfer paper can be suppressed small, and Discharge can be reduced, and transfer dust can be reduced. Therefore, it is possible to obtain a sharp image with less transfer dust in the process of electrostatic transfer from the intermediate transfer belt to transfer paper.
[0011]
Next, in the case of forming a color image, the color image transferred to the intermediate transfer belt has a height in the Z-axis direction (a direction perpendicular to the belt surface) of 10 μm and 30 μm for one color toner layer and three color toner layers. There is a difference. As a matter of course, the transfer efficiency is determined by applying a transfer bias suited to the worse condition. As a result, the transfer paper is excessively charged, and discharge occurs during transfer separation, resulting in transfer dust. In particular, dust of a multi-layer toner is conspicuous.
Therefore, in the present invention, the intermediate transfer belt has one or more elastic layers on a support, and has an elastic layer having a thickness of 0.1 to 0.2 mm and a hardness of 15 to 40 degrees on the outermost surface layer. With this configuration (claim 3), when pressure is applied between the intermediate transfer belt and the transfer paper, the toner bites into the surface soft elastic layer, and the toner and the transfer paper have good adhesion. As a result, the charge amount of the transfer paper can be suppressed to a small value, the discharge at the time of separation can be reduced, and the transfer dust can be reduced. Therefore, it is possible to obtain a sharp image with less transfer dust in the process of electrostatic transfer from the intermediate transfer belt to transfer paper. Incidentally, if the elastic layer of the intermediate transfer belt is too thick, the toner layer will shift, so in the present invention, the outermost surface layer has a thickness of 0.1 to 0.2 mm so as to have an optimum thickness. .
[0012]
Next, in the electrostatic transfer method in which a strong pressure is applied between the intermediate transfer belt and the transfer paper according to the present invention, the characteristics tend to be such that the toner or the toner and the intermediate transfer belt easily adhere to each other. That is, when pressure is applied to the toner, the toner is plastically deformed and the contact surface increases, and the external additive is buried in the toner and easily adheres by viscous force. Further, the toner between the intermediate transfer belt and the transfer paper may adhere to the transfer paper or the intermediate transfer belt when peeled off. When the toner adheres to the intermediate transfer belt, a transfer white spot occurs.
In the present invention, a surface treatment is performed on the elastic layer of the intermediate transfer belt to reduce the coefficient of friction of the surface layer of the intermediate transfer belt to 0.7 or less because the property that the toner is less likely to adhere to the surface of the intermediate transfer belt is the coefficient of friction. (Claim 4), even if toners adhere to each other, it is possible to prevent white spots by adhering to the transfer paper side. Therefore, by processing the friction coefficient of the surface of the intermediate transfer belt to 0.7 or less, it is possible to obtain an image with less transfer dust and less transfer white spots.
[0013]
Next, in the electrostatic transfer method in which a strong pressure is applied between the intermediate transfer belt and the transfer paper, the toner tends to adhere to the intermediate transfer belt and the transfer paper due to its viscosity. When the toner cohesion degree decreases, the toner becomes more dry and becomes stronger against pressure.On the other hand, when the toner cohesion degree increases, "stickiness" increases. It easily adheres to paper and the intermediate transfer belt. Therefore, in the electrostatic transfer, an optimum toner aggregation degree is required.
Therefore, in the image forming method and apparatus of the present invention, the transfer method according to any one of claims 1 to 4 is used, and a toner having a cohesion degree of 15 to 40% is used as a toner used for development. By optimizing the toner aggregation degree to 15 to 40%, it is possible to obtain an image with less transfer dust and less transfer white spots.
[0014]
Next, in the electrostatic transfer method in which a strong pressure is applied between the intermediate transfer belt and the transfer paper, the toner tends to adhere to the intermediate transfer belt and the transfer paper due to its viscosity. The higher the toner hardness, the harder it is to adhere and the higher the toner hardness, the harder it is to fix. On the other hand, when the toner hardness is low, the “stickiness” increases, and when pressure is applied to the toner, the toner easily adheres to the toner, transfer paper, and a transfer belt due to viscosity. Therefore, optimal hardness is required for electrostatic transfer.
Therefore, in the image forming method and apparatus of the present invention, the transfer method according to any one of claims 1 to 4 is used, and a toner having a hardness of 7 to 12 degrees is used as a toner used for development. Therefore, by optimizing the hardness of the toner to 7 to 12 degrees, it is possible to obtain an image with less transfer dust and less transfer white spots.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration, operation, and operation of the present invention will be described in detail with reference to the drawings.
In a color image forming apparatus using an intermediate transfer member (for example, an intermediate transfer belt), transfer dust is generated as a problem in a second transfer step of transferring a toner image from the intermediate transfer belt to a transfer material (for example, transfer paper). There's a problem. This transfer dust will be discussed with reference to FIG.
In FIG. 2, reference numeral 51 denotes an intermediate transfer belt, 56 denotes a transfer roller, and P denotes a transfer sheet. In a second transfer step of transferring the toner image from the intermediate transfer belt 51 to the transfer sheet P, before and after the transfer area [B]. In the areas [A] and [C] where the transfer paper P and the intermediate transfer belt 51 are not in contact, transfer dust occurs due to the influence of the electric field. The main cause is the discharge phenomenon when approaching.
[0016]
Here, the force F for transferring the toner from the intermediate transfer belt 51 to the transfer paper P is
F = qE (1)
q: charge amount of toner
E: Electric field around toner between transfer paper and intermediate transfer belt
And the electric field E around the toner is
E = (Vp−Vbelt) / (dp / εp + dt / εt + dbelt / εbelt + g) (2)
Vp-Vbelt: potential difference between transfer belt and transfer paper
dp / εp: dielectric thickness of transfer paper
dt / εt: dielectric thickness of toner layer
dbelt / εbelt: dielectric thickness of belt layer
g: Air gap (gap)
It is.
[0017]
In order to reduce the discharge in the areas [A] and [C], it is necessary to reduce the potential difference between the intermediate transfer belt and the transfer paper (transfer roller).
There are the following methods as an improvement measure.
1) When the air gap between the intermediate transfer belt and the transfer paper is reduced while keeping the electric field around the toner between the transfer paper and the intermediate transfer belt constant, the potential difference between the intermediate transfer belt and the transfer paper is obtained from the above equation (2). Can be reduced. As an actual means, a means for applying pressure is provided between the transfer roller as the transfer means and the intermediate transfer belt, and the pressure is applied between the transfer roller having a relatively hard rubber-like surface layer and the back roller of the intermediate transfer belt. In addition, it can be achieved by increasing the adhesion between the transfer paper and the intermediate transfer belt and reducing the substantial average gap.
2) In the case of a color image, it is necessary to transfer toner layers having different heights of one color toner and three color superimposed toner. Therefore, in order to correct the poor adhesion between the transfer paper and the toner, the intermediate transfer belt has a two-layer structure, and a soft rubber layer is thinly formed on the surface. Further, the aforementioned pressure is applied to bring the transfer paper and the toner into contact. Thereby, the gap around the toner can be reduced, and the potential difference between the transfer paper and the intermediate transfer belt can be reduced. As a result, the toner, the transfer paper, and the intermediate transfer belt have improved adhesion, and the transfer efficiency does not change. In addition, not only the toner dust in the transfer area [B] in FIG. Can be reduced, and transfer dust is reduced.
3) Further, in the present invention, transfer white spots in the pressure-applied transfer, which are observed in the conventional transfer, are improved. As a cause of transfer white spots, toner aggregates due to pressure and dust due to discharge at the time of separation is reduced, but toner sticks to the photoreceptor and intermediate transfer belt due to aggregation and drops out without being transferred to transfer paper It is. Therefore, as a countermeasure, a hard toner is used, in which the toners are hardly aggregated, and a toner having a characteristic that the toners do not adhere to the intermediate transfer belt even when pressure is applied during transfer is used. Further, it is assumed that the amount of charge on the transfer paper is reduced to prevent discharge during separation.
By the above means, the electric field around the toner is a sufficient value, and the charge amount of the transfer paper can be reduced.
This makes it possible to obtain a condition in which the potential difference between the intermediate transfer belt and the transfer paper becomes small at the time of peeling after transfer, so that a discharge is unlikely to occur, and it is possible to obtain an image with less transfer dust, sharpness, and less transfer whiteout.
[0018]
Hereinafter, specific embodiments of the present invention will be described.
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention, and shows an outline of a color image forming apparatus using a well-known electrophotographic system and using an intermediate transfer belt.
The image forming apparatus includes a drum-shaped photoconductor 1 as an image carrier, and the photoconductor 1 rotates in a direction indicated by an arrow in FIG. Around the photoreceptor 1, a charging unit 2, an exposure unit (latent image forming unit) 3, a developing unit 4, an intermediate transfer unit 5, and a cleaning unit 6 for performing an image forming process along the rotation direction. Are arranged. A transfer unit 56 for transferring paper is disposed below the intermediate transfer unit 5, and a transport belt 57 and a fixing unit 7 are disposed downstream of the transfer paper transfer unit 56 in the transfer paper transport direction. . Further, a paper feed bank 101 for storing the transfer paper is arranged at the lower part of the main body of the image forming apparatus, and a paper feed roller 102 and a transport roller 103 are provided in a transport path from the paper feed bank 101 to the transfer paper transfer means 56. , A registration roller 104 is provided. When the image forming apparatus is a copying machine or the like, a known document reading device (color scanner) 31 is provided at the upper part of the main body.
[0019]
In FIG. 1, various charging devices such as a charging charger, a charging roller, and a charging brush are used as the charging unit 2 to uniformly charge the surface of the photoconductor 1.
As the exposure unit (latent image forming unit) 3, for example, an optical scanning type exposure device 32 including a laser light source, an optical deflector (a rotating plane mirror, a rotating polygon mirror, a pidamiral mirror, etc.), a scanning image forming optical system, and the like is used. Then, a laser beam 34 modulated in accordance with image data is emitted from the exposure device 32, and is exposed on the surface of the photoconductor 1 via the folding mirror 33 to form an electrostatic latent image. In addition, as the exposure means, an optical writing device using a light emitting diode (LED) array and an imaging element array or the like can be used.
As the developing unit 4, for example, a rotary developing device (revolver type developing device) is used. In the rotary developing device 4, a yellow developing device 41 using yellow toner, a magenta developing device 42 using magenta toner, A four-color developing device including a cyan developing device 43 using a cyan toner and a black developing device 44 using a black toner is housed around a rotation axis O. These developing devices are rotated about the rotation axis O, and The developing device of that color is moved to a position facing the photoconductor 1, and the electrostatic latent image on the photoconductor 1 is developed with the toner of each color. Further, as each developing device, for example, a developing device of a two-component developing system is used, but a developing device of a one-component developing system can also be used.
The intermediate transfer unit 5 is, for example, an intermediate transfer belt device using an intermediate transfer belt 51 as an intermediate transfer member. The intermediate transfer belt 51 is supported by a plurality of rollers 52 to 55. Of the plurality of rollers, 52 is an intermediate transfer roller, which supports the intermediate transfer belt 51 at the intermediate transfer unit, and applies a transfer bias to electrostatically transfer the toner image on the photoconductor 1 to the intermediate transfer belt 51 ( First transfer). Reference numeral 55 denotes a backup roller that supports the intermediate transfer belt 51 in a transfer section on transfer paper. Incidentally, an intermediate transfer drum may be used as the intermediate transfer member.
The cleaning unit 6 is a cleaning device including a cleaning blade 61, a cleaning brush 62, toner recovery units 63 and 64, and recovers the transfer residual toner on the photoconductor 1.
The transfer paper transfer means 56 is, for example, a transfer roller. When the transfer from the intermediate transfer belt 51 to the transfer paper (second transfer) is performed, the transfer bias is brought into contact with the intermediate transfer belt 51 by a contact / separation mechanism (not shown) and the transfer bias is applied. The voltage is applied to transfer the toner image on the intermediate transfer belt 51 to transfer paper. Further, a transfer belt supported by a roller can be used as the transfer paper transfer unit.
The fixing unit 7 is, for example, a fixing device including a fixing roller 71 having a heat source (electric heater, halogen lamp, etc.) and a pressure roller 72 therein, and fixes the toner image transferred from the intermediate transfer belt 51 to transfer paper. I do.
[0020]
Since the image forming apparatus having the configuration shown in FIG. 1 is a one-drum intermediate transfer type color image forming apparatus, images of, for example, yellow, magenta, cyan, and black are sequentially formed on the photoreceptor 1, and the respective colors are formed. Are transferred to the intermediate transfer belt 51 in the order of formation, and a superimposed image of four colors is formed on the intermediate transfer belt.
More specifically, when the image forming operation is started, first, the photoconductor 1 is uniformly charged by the charger 2, and then a laser beam 34 corresponding to yellow image data is emitted from the exposure device 32 of the exposure unit 3. Exposed to form a yellow electrostatic latent image. The formed latent image is developed with yellow toner of a yellow developing device 41 to be visualized, and then electrostatically transferred onto the intermediate transfer belt 51. Further, the transfer residual toner remaining on the surface of the photoconductor after the transfer is removed by the cleaning device 6. Next, the same processes from charging to intermediate transfer and cleaning are repeated in the order of magenta, cyan and black, and four color toners are superimposed and transferred onto the intermediate transfer belt 51. Next, although not shown, the transfer paper transfer roller 56 separated from the intermediate transfer belt 51 comes into contact with the intermediate transfer belt 51 by the contact / separation mechanism, and in synchronization with this, the transfer paper is fed from the paper feed bank 101. The toner image is transferred to the nip between the intermediate transfer belt 51 and the transfer paper transfer roller 56 by the registration roller 104, and four colors of the toner image on the intermediate transfer belt 51 are simultaneously transferred to the transfer paper sandwiched between the nip portions. The transfer paper separated from the intermediate transfer belt 51 is transported to the fixing device 7 by the transport belt 57, and the toner image is fixed on the transfer paper by the heated fixing roller 71 and the pressure roller 72 of the fixing device 7, and after fixing. Is discharged to a paper discharge tray or the like outside the apparatus.
[0021]
Next, a characteristic transfer configuration of the present invention used in the image forming apparatus having the above configuration and operation will be described with reference to FIG. FIG. 3 shows only the configuration of the second transfer unit that transfers the toner image on the intermediate transfer belt 51 to the transfer paper P.
As shown in FIG. 3, the transfer roller 56 has a solid elastic layer 56a made of EPDM, silicone, NBR, urethane or the like on a core metal 56b having a diameter of φ20 to 30 mm made of stainless steel (SUS), iron (Fe) or the like. The elastic layer 56a has a thickness of 0.1 to 1.0 mm, a hardness of 60 to 80 degrees (Asker C / 1 kg load), and a volume resistance of 1 × 10 ⁸ ~ 1 × 10 ¹¹ Ωcm, and the surface resistance is optimally equal to or higher than the volume resistance.
A pressurizing means is provided in a contact / separation mechanism (not shown) for bringing the transfer roller 56 into and out of contact with the intermediate transfer belt 51. As the pressurizing means, bearings 56c are provided at both ends of the shaft of the transfer roller 56. The bearings 56c at both ends are pressed in the direction of the intermediate transfer belt 51 by a spring (spring or the like) 56d. When the transfer roller 56 comes into contact with the intermediate transfer belt 51 by a contact / separation mechanism (not shown). The transfer roller 56 is pressed against the intermediate transfer belt 51 (backup roller 55). The measurement of the pressing force is presented as a value obtained by dividing the total pressing force of the springs 56d provided at both ends of the shaft of the transfer roller 56 by the length of the transfer roller, and the unit is shown in N / cm.
[0022]
Next, the configuration and operation of the intermediate transfer belt 51 used in the image forming apparatus of the present invention will be described.
The layer structure of the intermediate transfer belt 51 has a structure in which two elastic layers having different hardness are provided on a support, and a soft elastic layer having a thickness of 0.1 to 0.2 mm and a hardness of 15 to 40 degrees is provided on the surface layer side. The elastic layer (intermediate elastic layer) inside is formed of an elastic layer having a thickness of 0.1 to 0.3 mm and a hardness of 60 to 80 degrees. Further, in order to prevent the toner from adhering, the surface of the elastic layer on the surface layer is subjected to a coating treatment with a fluororesin (for example, Teflon (registered trademark)) so that the surface friction coefficient is 0.7 or less, and the volume resistance is reduced. 2 × 10 ¹² Ωcm, surface resistivity is 4 × 10 ¹² Ω. The operation of the intermediate transfer belt 51 will be described with reference to FIGS.
[0023]
FIG. 4 is a view showing a transfer paper transfer model in the case where a conventional intermediate transfer belt composed of only a support is used. The toner transferred onto the intermediate transfer belt is random from one to three layers. In this state, when the transfer paper is brought into contact with the transfer paper by the transfer roller, the contact and the distance between the one color toner layer and the multi-layer toner layer with the transfer paper are different, and a uniform electric field E cannot be obtained. Of the toner layer, which results in a large amount of current flowing to the transfer paper. As a result, the multi-layered toner layer collapses or discharges easily at the time of separation, resulting in transfer dust.
[0024]
Next, FIG. 5 is a view showing a transfer paper transfer model when the intermediate transfer belt of the present invention is used. The intermediate transfer belt according to the present invention has a soft elastic layer as a surface layer, and applies pressure between the intermediate transfer belt 51 and the transfer paper transfer roller 56 by a spring 56d as shown in FIG. As a result, since the toner layer bites into the surface layer of the intermediate transfer belt 51 and further pressure is applied, the adhesion between the transfer paper P and the transfer roller 56 and the intermediate transfer belt 51 is improved, and a minimum transfer current is sufficient. An image with less transfer dust is obtained both during transfer and transfer separation.
[0025]
Here, the measurement of the resistance value and the friction coefficient of the intermediate transfer belt will be described.
As the surface resistance and the volume resistance of the intermediate transfer belt, values measured at an applied voltage of 500 V and a measurement time of 10 seconds using High Leicester manufactured by Mitsubishi Yuka.
The coefficient of friction was measured using a Friction Abrasion Analyzer DF, PM-SS manufactured by Kyowa Interface Chemical Co., Ltd., with a stainless ball indenter weight of 100 g.
[0026]
Next, the characteristics of the toner used for development in the image forming method (apparatus) of the present invention will be described.
The smaller the cohesive force of the toner used for development in the image forming method (apparatus) of the present invention, the better. However, when the cohesive force of the toner is too small, the fluidity of the toner is too good and transfer dust tends to occur. When the cohesive force of the toner is large, the toners easily adhere to each other and adhere to the intermediate transfer belt 51. , Transfer white spots easily occur.
Here, the cohesive force of the toner can be expressed as a cohesion degree (%). Therefore, it can be said that the larger the value of the degree of aggregation, the stronger the aggregation of the toner.
[0027]
As a method of measuring the degree of aggregation of the toner, "Powder Tester PT-N" (manufactured by Hosokawa Micron Corporation) is used as a measuring device, and the operation method basically follows the operation manual of "Powder Tester PT-N". The following points have changed. 1. Sieve used: 75 μm, 45 μm, 22 μm.
2. Vibration time: 30 seconds.
[0028]
The aggregation degree of the toner used for development in the image forming method (apparatus) of the present invention is 15 to 40%, and more preferably 15 to 35%. When the agglomeration degree of the toner is 15% or less, the fluidity of the toner is too good, and dust is easily generated at the time of transfer. When the degree of aggregation is 40% or more, the aggregation of the toner is increased, and the transferability is deteriorated. Further, transfer white spots occur.
Further, the hardness of the toner used for development in the image forming method (apparatus) of the present invention is related to the adhesion between toners and the fixing characteristics. In the case of the pressure transfer system as in the present invention, the higher the hardness, the better, but the fixing characteristics are adversely affected, so the optimum value is used.
[0029]
As a method for measuring the toner hardness, a “micro compression tester MCTM-500 (manufactured by Shimadzu Corporation)” is used as a measuring device. As a measuring method, first, the molten toner is rolled and cooled to obtain a flat plate. Next, the surface is polished using # 1200 sandpaper to make it smooth. Then, measurement is performed five times by applying a load of 1.0 gf, and the average value is defined as hardness.
[0030]
The hardness of the toner used for development in the image forming method (apparatus) of the present invention is 7 to 12, and more preferably 8 to 11. When the hardness of the toner is 7 or less, when the toner particles come into contact with each other, the particles are plastically deformed, so that the contact area between the toners is increased, the cohesive force of the toner is increased, and it is difficult to make the toner layer uniform. When the hardness of the toner is 12 or more, there is no problem in the transfer step, but there is a possibility that the fixing property is deteriorated in the fixing step.
[0031]
Next, the formulation of the toner used for development in the image forming method (apparatus) of the invention will be described.
As the binder resin used for the toner used in the present invention, all conventionally known resins can be used. For example, styrene, poly-α-stillstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene Styrene such as maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer Resin (mono- or copolymer containing styrene or styrene substituent), polyester resin, epoxy resin, vinyl chloride resin, rosin-modified maleic resin, phenol resin, polyethylene resin, polypropylene resin, petroleum resin, polyurethane resin, Ketone resin, ethylene-ethylene Acrylate copolymer, xylene resin, polyvinyl butyrate resin and the like.
[0032]
In the toner used in the present invention, any of known release agents can be used. In particular, a free fatty acid type carnauba wax, montan wax and oxidized rice wax can be used alone or in combination.
As the external additive, inorganic fine particles can be preferably used. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, Diatomaceous earth, chromium oxide, cerium oxide, pengara, antimony trioxide, magnesium oxide, zirconium oxide, parium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like can be given.
[0033]
The toner used in the present invention may optionally contain a charge control agent. As the charge control agent, any known charge control agents can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine) Modified quaternary ammonium salts), alkylamides, phosphorus alone or compounds, tungsten alone or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts.
As the colorant used in the toner used in the present invention, all of pigments and dyes conventionally used as toner colorants are applied. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, calco oil blue, oil black, azo oil black and the like are not particularly limited.
[0034]
The method for producing the toner used in the present invention may be a conventionally known method, in which a binder resin, a magnetic material, a release agent, a colorant, and in some cases, a charge control agent and the like are mixed using a mixer or the like. After kneading using a kneader such as a hot roll or an extruder, the mixture is solidified by cooling, pulverized by pulverization using a jet mill, turbojet, kryptron or the like, and then classified.
In addition, a mixer such as a super mixer or a Henschel mixer is used to add the inorganic powder or the fatty acid metal salt to the toner.
[0035]
【Example】
Hereinafter, the present invention will be described with reference to specific examples.
<Transfer rate, fixability, transfer dust, transfer white spot evaluation method>
As the evaluation machine, the transfer portion of a color copying machine manufactured by Ricoh (IMAZIO Color 5100) was modified and used. The unit configuration of the image forming unit is the same as the schematic configuration of the color image forming apparatus shown in FIG. As the developing means, a rotary developing device 4 having four color two-component developing units 41 to 44 is used. As the intermediate transfer means 5, an intermediate transfer belt 51 is used. To perform electrostatic transfer (first transfer) on the intermediate transfer belt 51. After the above-described processes of forming latent images of four colors of yellow to black, developing, and intermediate transfer, the transfer paper transfer roller 56 is brought into contact with the intermediate transfer belt 51 by a contact / separation mechanism (not shown), and the above-described pressing means is used. To apply a transfer bias to the transfer roller 56 to perform electrostatic transfer (second transfer) from the intermediate transfer belt 51 to transfer paper. The transfer paper on which the four-color superimposed image has been transferred is conveyed to the fixing device 7 by the conveyance belt 57. In the fixing device 7, the nip portion between the fixing roller 71 and the pressure roller 72 has a surface pressure of 9.3 N / cm. ² Is performed at a pressure of 165 to 185 ° C.
Using the image forming apparatus having the above-described configuration, a gray scale, a sharpness chart, a character chart, and a test chart centering on color patches formed from dots having a pixel density of 600 dpi (dot / inch) are printed out and sampled. Image obtained.
[0036]
<Evaluation of transfer rate>
The developed chart on the photoconductor 1 is transferred to a transfer sheet via the intermediate transfer belt 51, and the machine is stopped when the transfer sheet is on the transport belt 57. Paying attention to the black solid portion of the chart, the transfer residual toner amount of the black solid portion on the photoreceptor 1 is peeled off with an adhesive tape, and the residual toner amount on the photoreceptor is obtained. On the other hand, the toner transferred to the transfer paper cuts off a solid black portion and blows off the toner with compressed air. Calculate the amount of transferred toner from the weight before and after blowing off,
(Transfer toner amount / (transfer toner + remaining toner amount)) × 100 (%)
To determine the transfer rate (%). The allowable value of the transfer rate is 70% or more under a general environment. A transfer rate of 80% or more was judged as “○”, 70 to 79% was judged as “Δ”, and a transfer rate of 69% or less was judged as “x”. The allowable level is “△” or more.
[0037]
<Evaluation of fixability>
Next, the fixability is evaluated by the smear method. A cloth adhered to a weight of 8.8 N / 15φ at a halftone portion of ID: 0.6 to 0.8 was placed on a transfer paper, and the density on the cloth when rubbed five times was evaluated. A level of 0.3 or less having no problem was indicated by “○”, an acceptable level of 0.5 or less was indicated by “Δ”, and a level of 0.51 or more was evaluated by “×”.
[0038]
<Evaluation of transfer dust and transfer void>
Since a general-purpose evaluation method has not been established for the transfer dust and the transfer white spot, the sample and the rank sample were visually evaluated by a sensory evaluation method. FIG. 6 shows a sample of the rank of the transferred dust, and FIG. Of each of the three types of images, rank 3 “で” is the allowable level, higher than “OK”, and those less than rank 3 “△” are “NG”.
[0039]
[Example 1]
Next, as a more specific embodiment, an image forming apparatus having the same configuration as that of FIG. 1 (manufactured by Ricoh, Imagio Color 5100) was used as a test machine, and the transfer section (intermediate transfer belt, second transfer section) of the test machine was used. ) Was modified and used. Further, the intermediate transfer belt was processed so that the contact between the photosensitive member 1 and the intermediate transfer belt 51 and the contact between the intermediate transfer belt 51 and the transfer roller 56 were stabilized.
[0040]
Here, a method of manufacturing the intermediate transfer belt will be described.
・ Polyvinylidene fluoride (KF-850; Kureha Chemical Industry): 100 parts by weight
・ Carbon black (Printex 40; Degussa): 5 parts by weight
・ Molybdenum disulfide: 20 parts by weight
A seamless belt having a thickness of 0.2 to 0.3 mm was prepared by extruding a mixture obtained by melting and kneading, and was used as a support for the intermediate transfer belt. On this support surface, a silicone elastic layer having a hardness of 15 to 40 degrees (Asker C / 1 kg load) and a thickness of 0.1 to 0.2 mm was provided. Further, the surface thereof was subjected to a coating treatment with a fluororesin (for example, Teflon (registered trademark)) (coating and drying by heating to form a resin layer of 20 μm). Resistance is 2 × 10 in volume resistance ¹² Ωcm, surface resistance 4 × 10 ¹² Ω. The coefficient of surface friction was 0.22.
[0041]
After the first transfer from the photosensitive member 1 to the intermediate transfer belt 51 was performed using the intermediate transfer belt 51 having the above-described configuration, a second transfer for transferring the toner on the intermediate transfer belt 51 to transfer paper was performed. The means for pressing the transfer roller 56 against the intermediate transfer belt 51 is pressing by the spring 56d of the transfer roller 56 shown in FIG. 3, and the transfer pressure is set to 0.5, 1.0, 5.0, 8.0 [ N / cm], and the current flowing by controlling the transfer bias voltage applied between the transfer roller 56 and the intermediate transfer belt 51 is set to four levels of 0.03, 0.05, 0.2, and 0.3 μA / cm. The test chart described above was transferred and printed by the image forming apparatus. The evaluation was performed by transfer dust (see FIG. 6) and transfer whitening (see FIG. 7). The evaluation results are shown in Table 1 below.
The current value is a condition where the transfer current is 0.3 to 0.4 μA / cm and the pressure is about 1 N / cm. The toner used was a toner having a toner formulation 5 described later.
[0042]
[Table 1]

[0043]
From the results shown in Table 1, using the above-mentioned intermediate transfer belt, the pressure was 1.0 to 5.0 N / cm, and the transfer current was 0.05 to 0.20 μA / cm. It was in a good range with omission. When the transfer current is increased, a leak phenomenon of the transfer paper occurs, the reverse charge of the toner is injected, and the transfer rate tends to decrease. On the other hand, if the transfer current is too small, the force (F in the above-described formula (1)) to be attracted to the transfer paper becomes small, and transfer is not performed. Regarding the transfer pressure, if the pressure is as small as 0.05 N / cm, the adhesion between the transfer paper and the intermediate transfer belt is weak, the transfer rate is reduced, and transfer dust is likely to occur. On the other hand, if the pressure is increased to 10.0 N / cm, the pressure is too strong, and if the toner layer is large during transfer, the toner easily adheres to the intermediate transfer belt and easily collapses, and as a result, good data cannot be obtained. Was.
The surface characteristics of the used intermediate transfer belt are too soft if the Asker C hardness is less than 15 degrees, and the toner remains on the intermediate transfer belt. On the other hand, when the hardness exceeds 40 degrees, the toner is too hard, so that the toner does not easily penetrate the toner in the Z-axis direction, and the air gap cannot be reduced.
Further, if the thickness of the soft elastic layer on the intermediate transfer belt is less than 0.1 mm, coat unevenness is large and sufficient toner penetration cannot be obtained. On the other hand, when the thickness exceeds 0.2 mm, as in the case where the pressure is large, the toner easily adheres to the intermediate transfer belt and easily collapses, and as a result, good data cannot be obtained.
[0044]
[Example 2]
In the same manner as in Example 1, when the surface of the elastic layer of the intermediate transfer belt is coated with a fluorine-based resin, spray coating is performed with the following three levels of prescription, and heat drying is performed. A transfer belt was created.
[0045]
<Coating treatment formula 1>
・ Fluorine resin (Lumiflon 601C; Asahi Glass): 100 parts by weight
・ Lumiflon curing agent: 20 parts by weight
-Boron nitride: 20 parts by weight
<Coating treatment prescription 2>
-Formula 1 material: 140 parts by weight
・ Fluorine fine powder (1 μm): 5 parts by weight
<Coating treatment prescription 3>
-Formula 1 material: 140 parts by weight
・ Fluorine fine powder (1 μm): 10 parts by weight
[0046]
The above formulation was mixed with 200 parts of methyl isobutyl ketone and 100 parts of xylene, milled by a ball mill for about 60 hours, and spray-coated.
The friction coefficient of the intermediate transfer belt coated with the prescription 1 was 0.22, the friction coefficient of the intermediate transfer belt coated with the prescription 2 was 0.68, and the friction of the intermediate transfer belt coated with the prescription 3 was The coefficient was 0.96.
[0047]
Using these three types of intermediate transfer belts, image samples were obtained with the same device configuration and method as in Example 1.
The surface layer of the support of the intermediate transfer belt was provided with a silicone elastic layer having a hardness of 15 to 40 degrees (Asker C / 1 kg load) and a thickness of 0.1 to 0.2 mm. Then, a coating layer of the above-mentioned fluororesin was provided thereon. The transfer pressure was 3.2 N / cm, and the transfer current was 0.15 μA / cm.
Table 2 below shows the results of evaluation of transfer dust (see the evaluation rank in FIG. 6) and transfer white spots (see the evaluation rank in FIG. 7).
[0048]
[Table 2]

[0049]
From the above results, a good condition is that the coefficient of friction of the surface layer of the intermediate transfer belt is 0.7 or less. If the friction coefficient is small, the transfer pressure is applied to the toner, the transfer paper and the intermediate transfer belt, and even if the toners adhere to each other, they do not adhere to the intermediate transfer belt, and the toner after transfer separation moves onto the transfer paper. On the other hand, if the coefficient of friction is too high, the adhesive force between the toner and the intermediate transfer belt increases, and the toner and the intermediate transfer belt tend to adhere to each other during transfer separation. The toner remains on the belt and becomes a transfer white spot, resulting in an abnormal image.
[0050]
[Example 3]
Next, examples of the characteristics of the toner prepared by changing the formulation of the toner used for development and the transfer characteristics will be described.
<Toner formulation 1>
-Polyester resin (weight average molecular weight: 310,000, Tg: 65 ° C): 44 parts by weight
-Styrene-n-butyl acrylate copolymer (weight average molecular weight: 85000, Tg: 68 ° C): 40 parts by weight
・ Carnauba wax: 5 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 10 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 1 part by weight
[0051]
After kneading at 130 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to obtain a weight average particle size of 8.5 μm, and then using a Henschel mixer, silica (R-972 Nippon Aerosil) ) Was mixed to obtain a toner. This toner has a hardness of 8, a cohesion degree of 30%, and a volume resistivity of 8.5 × 10. ⁸ Ωcm.
[0052]
<Toner formulation 2>
Polyester resin (weight average molecular weight: 185000, Tg: 67 ° C): 71 parts by weight
・ Carnauba wax (average particle size: 300 μm): 3 parts by weight
-Iron trioxide (EPT-1000: Toda Kogyo): 15 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 10 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 1 part by weight
[0053]
After kneading at 160 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to a weight average particle size of 5.5 μm, and then using a Henschel mixer, silica (R-972 Nippon Aerosil) 1 0.0% by weight to obtain a toner. This toner has a hardness of 11, a cohesion of 8.0%, and a volume resistivity of 5.5 × 10 ⁸ Ωcm.
[0054]
<Toner formulation 3>
・ Styrene / n-butyl methacrylate / 2-ethylhexyl acrylate copolymer (composition ratio: 75/10/15, weight average molecular weight: 210,000 Tg: 57 ° C.): 55 parts by weight
Polyester resin (weight average molecular weight: 160,000 Tg: 64 ° C.): 23 parts by weight
・ Polyethylene wax (molecular weight 900): 10 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 10 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 2 parts by weight
[0055]
After kneading at 90 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying to a weight average particle size of 7.5 μm with a pneumatic pulverizer, and then using a Henschel mixer, silica (R-972 Japan) (Aerosil) 0.2% by weight was mixed to obtain a toner. This toner has a hardness of 6, a cohesion degree of 55.0%, and a volume resistivity of 8.8 × 10 ⁸ Ωcm.
[0056]
<Toner formulation 4>
-Polyester resin (weight average molecular weight: 274000, Tg: 68 ° C): 79 parts by weight
-Polyethylene wax (molecular weight 900): 3 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 15 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 3 parts by weight
[0057]
After kneading at 150 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with an airflow type pulverizer to a weight average particle size of 9.5 μm, and then using a Henschel mixer, silica (R-972 Japan) (Aerosil) was added to obtain a toner. This toner has a hardness of 14, a cohesion of 8.5%, and a volume resistivity of 4.2 × 10. ⁸ Ωcm.
[0058]
<Toner formulation 5>
-Polyester resin (weight average molecular weight: 310,000, Tg: 65 ° C): 49 parts by weight
-Styrene-n-butyl acrylate copolymer (weight average molecular weight: 85000, Tg: 68 ° C): 35 parts by weight
・ Carnauba wax: 4 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 10 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 2 parts by weight
[0059]
After kneading at 130 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to a weight average particle size of 8.5 μm, and then using silica (R-972 Japan) using a Henschel mixer. (Aerosil) of 0.5% by weight to obtain a toner. This toner has a hardness of 10, a cohesion of 20%, and a volume resistivity of 9.5 × 10 ⁸ Ωcm.
[0060]
<Toner formulation 6>
-Polyester resin (weight average molecular weight: 185000, Tg: 67 ° C): 73 parts by weight
・ Carnauba wax (average particle size: 300 μm): 5 parts by weight
-Iron trioxide (EPT-1000: Toda Kogyo): 10 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 10 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 2 parts by weight
[0061]
After kneading at 160 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to obtain a weight average particle size of 6.5 μm, and then using a Henschel mixer, silica (R-972 Japan) (Aerosil) 0.75% by weight was mixed to obtain a toner. This toner has a hardness of 11, an agglomeration degree of 31%, and a volume resistivity of 9.8 × 10. ⁸ Ωcm.
[0062]
<Toner formulation 7>
-Polyester resin (weight average molecular weight: 310,000, Tg: 65 ° C): 56 parts by weight
-Styrene-n-butyl acrylate copolymer (weight average molecular weight: 85000, Tg: 68 ° C): 35 parts by weight
・ Carnauba wax: 3 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 5 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 1 part by weight
[0063]
After low-temperature kneading at 80 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to a weight average particle size of 8.5 μm, and then using a Henschel mixer, silica (R-972) was used. (Nippon Aerosil) 0.5% by weight was mixed to obtain a toner. This toner has a hardness of 10, a cohesion degree of 15%, and a volume resistivity of 3.5 × 10 ⁹ Ωcm.
[0064]
<Toner formulation 8>
-Polyester resin (weight average molecular weight: 310,000, Tg: 65 ° C): 56 parts by weight
-Styrene-n-butyl acrylate copolymer (weight average molecular weight: 85000, Tg: 68 ° C): 35 parts by weight
・ Carnauba wax: 3 parts by weight
・ Carbon black (# 44: Mitsubishi Chemical): 5 parts by weight
・ Charge control agent (Spiron Black TR-H: Hodogaya Chemical): 1 part by weight
[0065]
After low-temperature kneading at 80 ° C. using a twin-screw extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to a weight average particle size of 8.5 μm, and then, using a Henschel mixer, silica (R-972) 1.0% by weight of Nippon Aerosil) and 0.20 part by weight of fine zinc stearate powder were mixed to obtain a toner. This toner has a hardness of 10, a cohesion of 35.0%, and a volume resistivity of 1.8 × 10 ⁹ Ωcm.
[0066]
The transfer characteristics were evaluated under the same conditions as in Example 2 using the toners prepared according to the above Formulations 1 to 8. As the intermediate transfer belt, an intermediate transfer belt having a surface friction coefficient of 0.68 was used.
As evaluation items, transfer dust (see the rank sample in FIG. 6) and transfer blank (see the rank sample in FIG. 7) were evaluated, and favorable conditions were selected for both items. The evaluation results are shown in Table 3 below.
[0067]
[Table 3]

[0068]
According to the above evaluation data, toner having a hardness of 8 to 11 and a cohesion of 15 to 35% shows well-balanced toner characteristics in an image in transfer.
According to this result, the degree of aggregation of the toner is 15 to 40%, more preferably 15 to 35%. When the toner agglomeration degree is 15% or less, the fluidity of the toner is too good, and dust tends to be generated at the time of transfer. Further, when the toner aggregation degree is 40% or more, the aggregation force of the toner is increased, and transferability is deteriorated. Further, transfer white spots occur.
[0069]
The toner hardness is 7 to 12, more preferably 8 to 11. When the toner hardness is 7 or less, when the toner particles come into contact with each other, the toner particles are plastically deformed, so that the contact area between the toners increases, the cohesive force of the toner increases, and the toner layer and the intermediate transfer belt easily adhere to each other. Transfer white spots easily occur. When the toner hardness is 12 or more, there is no problem in the transfer step, but there is a possibility that the fixing property is deteriorated in the fixing step.
[0070]
【The invention's effect】
As described above, in the transfer method of the present invention, the elastic layer is provided on the surface of the surface of the intermediate transfer member (for example, the intermediate transfer belt) to which the toner is attached, and the transfer means (the transfer roller or the transfer belt) and the intermediate transfer belt. A means for applying pressure is provided between the transfer means and the transfer means so that a transfer bias current between the intermediate transfer belt and the transfer means is 0.05 to 0.2 μA / cm (claim 1). Since a pressure of 1 to 10 N / cm is applied between the backup rollers of the intermediate transfer belt (claim 2), a transfer electric field can be applied irrespective of the toner height. , The amount of charge can be suppressed to a small value, the discharge at the time of separation can be reduced, and the transfer dust can be reduced. Therefore, a sharp image with less transfer dust can be obtained in the process of performing electrostatic transfer from the intermediate transfer belt to transfer paper.
[0071]
In the transfer method of the present invention, the intermediate transfer belt has one or more elastic layers on a support, and has a thickness of 0.1 to 0.2 mm on the outermost surface layer and a hardness of 15 to 40 degrees. Because of the configuration having the elastic layer (Claim 3), by applying pressure between the intermediate transfer belt and the transfer paper, the toner bites into the surface soft elastic layer, and the adhesion between the toner and the transfer paper improves. As a result, the charge amount of the transfer paper can be suppressed to a small value, the discharge at the time of separation can be reduced, and the transfer dust can be reduced. Therefore, a sharp image with less transfer dust can be obtained in the step of electrostatic transfer from the intermediate transfer belt to transfer paper. Incidentally, if the elastic layer of the intermediate transfer belt is too thick, the toner layer will shift, so in the present invention, the outermost surface layer has a thickness of 0.1 to 0.2 mm so as to have an optimum thickness. .
[0072]
Further, in the transfer method according to the present invention, the surface treatment is performed on the elastic layer of the intermediate transfer belt so that the friction coefficient of the surface layer of the intermediate transfer belt is 0.7 or less. Also, even when toners adhere to each other, they can also adhere to the transfer paper side and prevent white spots. Therefore, by processing the friction coefficient of the surface of the intermediate transfer belt to 0.7 or less, it is possible to obtain an image with less transfer dust and less transfer white spots.
[0073]
In the image forming method and apparatus of the present invention, the transfer method according to any one of claims 1 to 4 is used, and a toner having a degree of aggregation of 15 to 40% is used as a toner used for development. By optimizing the toner cohesion to 15 to 40%, it is possible to obtain an image with less transfer dust and less transfer white spots.
In the image forming method and apparatus of the present invention, the transfer method according to any one of claims 1 to 4 is used, and a toner having a hardness of 7 to 12 degrees is used as a toner used for development. By optimizing the hardness of the toner to 7 to 12 degrees, it is possible to obtain an image with less transfer dust and less transfer white spots.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a transfer dust generation mechanism when a toner image is transferred from an intermediate transfer belt to transfer paper.
FIG. 3 is a schematic main part configuration diagram illustrating a configuration example of a second transfer unit that transfers a toner image from an intermediate transfer belt to transfer paper.
FIG. 4 is a diagram illustrating a transfer paper transfer model when a conventional intermediate transfer belt including only a support is used when a toner image is transferred from the intermediate transfer belt to transfer paper.
FIG. 5 is a diagram illustrating a transfer paper transfer model when the intermediate transfer belt of the present invention is used when a toner image is transferred from the intermediate transfer belt to transfer paper.
FIG. 6 is a diagram showing an evaluation rank sample of a transfer dust.
FIG. 7 is a diagram showing a sample evaluation rank of transfer white spots.
[Explanation of symbols]
1 Photoconductor (image carrier)
2 Charger (charging means)
3 Exposure means (latent image forming means)
4. Rotary developing device (developing means)
5 Intermediate transfer belt device (intermediate transfer means)
6. Cleaning device (cleaning means)
7 Fixing device (fixing means)
32 Exposure equipment
33 Folded mirror
34 Laser light
41 Yellow developing unit
42 Magenta developing unit
43 cyan developing unit
44 Black developing unit
51 Intermediate transfer belt (intermediate transfer body)
52 Intermediate transfer roller
55 Backup roller
56 Transfer paper transfer roller (transfer paper transfer means)
57 Conveyor belt
61 Cleaning blade
62 Cleaning brush
71 Fixing roller
72 Pressure roller
101 paper feed bank
102 Paper feed roller
103 transport roller
104 registration roller

Claims (8)

In a transfer method of electrostatically transferring a toner image transferred from an image carrier to an intermediate transfer member to a transfer material using a transfer unit,
An elastic layer on a surface layer of the intermediate transfer member to which the toner is attached, a unit for applying pressure between the transfer unit and the intermediate transfer unit, and a transfer bias between the intermediate transfer unit and the transfer unit. A transfer method, wherein the current is 0.05 to 0.2 μA / cm. The transfer method according to claim 1,
The intermediate transfer member is an intermediate transfer belt supported by a plurality of rollers, the transfer unit is a transfer roller or a transfer belt supported by rollers, and 1 to 1 between the transfer unit and a backup roller of the intermediate transfer belt. A transfer method characterized by applying a pressure of 10 N / cm. 3. The transfer method according to claim 1, wherein the intermediate transfer body has one or more elastic layers on a support, and the outermost surface layer has a thickness of 0.1 to 0.2 mm and a hardness of 15 to 40. A transfer method characterized in that the transfer method has a configuration having an elastic layer. The transfer method according to claim 1, 2, or 3,
A transfer method, wherein a surface treatment is performed on the elastic layer of the intermediate transfer member, and a friction coefficient of the surface layer of the intermediate transfer member is reduced to 0.7 or less. Forming a latent image on an image carrier, developing the latent image with toner to form a toner image, and transferring the toner image to an intermediate transfer member one or more times; After the toner image of one or more colors is transferred to the transfer material, the toner image transferred to the intermediate transfer body is electrostatically transferred to a transfer material using a transfer unit, and the toner image transferred to the transfer material is transferred to the transfer material. An image forming method for fixing an image to form an image,
An image forming method using the transfer method according to claim 1. The image forming method according to claim 5,
An image forming method, wherein a toner having a cohesion degree of 15 to 40% is used as a toner used for development. The image forming method according to claim 5,
An image forming method, wherein a toner having a hardness of 7 to 12 degrees is used as a toner used for development. Latent image forming means for forming a latent image on an image carrier, developing means for developing the latent image with toner to form a toner image, intermediate transfer means for transferring the toner image to an intermediate transfer member, In an image forming apparatus including a transfer unit that electrostatically transfers a toner image transferred to an intermediate transfer body to a transfer material, and a fixing unit that fixes the toner image transferred on the transfer material,
An image forming apparatus using the image forming method according to claim 5.

Images