JP4204203B2 - Image forming method, image forming apparatus, and toner container - Google Patents

Description

【００６６】
図１は、本発明の現像装置の実施例を採用した画像形成装置の現像装置要部の概略構成図である。実際の実施例では本現像装置をリコー製複写機ＭＦ−２００を改造した改造機に組み込み評価した。以下、その詳細について示す。
潜像担持体である感光体ドラム（１）の側方に配設された現像装置（１３）は、支持ケース（１４）、現像剤担持体としての現像スリーブ（１５）、現像剤収容部材（１６）、現像剤規制部材としての第１ドクターブレード（１７）等から主に構成されている。
【００６７】
感光体ドラム（１）側に開口を有する支持ケース（１４）は、内部にトナー（１８）を収容するトナー収容部としてのトナーホッパー（１９）を形成している。トナーホッパー（１９）の感光体ドラム（１）側寄りには、トナー（１８）と磁性粒子であるキャリアとからなる現像剤（２２）を収容する現像剤収容部（１６ａ）を形成する現像剤収容部材（１６）が、支持ケース（１４）と一体的に設けられている。また、現像剤収容部材（１６）の下方に位置する支持ケース（１４）には、対向面（１４ｂ）を有する突出部（１４ａ）が形成されており、現像剤収容部材（１６）の下部と対向面（１４ｂ）との間の空間によって、トナー（１８）を供給するためのトナー供給開口部（２０）が形成されている。
【００６８】
トナーホッパー（１９）の内部には、図示しない駆動手段によって回動されるトナー供給手段としてのトナーアジテータ（２１）が配設されている。トナーアジテータ（２１）は、トナーホッパー（１９）内のトナー（１８）をトナー供給開口部（２０）に向けて撹拌しながら送り出す。また、トナーホッパー（１９）の、感光体ドラム（１）と対向する側には、トナーホッパー（１９）内のトナー（１８）の量が少なくなったときにこれを検知するトナーエンド検知手段（１４ｃ）が配設されている。
【００６９】
感光体ドラム（１）とトナーホッパー（１９）との間の空間には、現像スリーブ（１５）が配設されている。図示しない駆動手段で図の矢印方向に回転駆動される現像スリーブ（１５）は、その内部に、現像装置（１３）に対して相対位置不変に配設された、磁界発生手段としての図示しない磁石を有している。
現像剤収容部材（１６）の、支持ケース（１４）に取り付けられた側と対向する側には、第１ドクターブレード（１７）が一体的に取り付けられている。第１ドクターブレード（１７）は、その先端と現像スリーブ（１５）の外周面との間に一定の隙間を保った状態で配設されている。
【００７０】
現像剤収容部材（１６）の、トナー供給開口部（２０）の近傍に位置する部位には、規制部材としての第２ドクターブレード（２３）が配設されている。第２ドクターブレード（２３）は、その自由端が現像スリーブ（１５）の外周面に対して一定の隙間を保つべく、現像スリーブ（１５）の表面に形成される現像剤（２２）の層の流れを妨げる方向、すなわち、自由端を現像スリーブ（１５）の中心に向けて、基端を現像剤収容部材（１６）に一体的に取り付けられている。
現像剤収容部（１６ａ）は、現像スリーブ（１５）の磁力が及ぶ範囲で、現像剤（２２）を循環移動させるに十分な空間を有するように構成されている。
【００７１】
なお、対向面（１４ｂ）は、トナーホッパー（１９）側から現像スリーブ（１５）側に向けて下向きに傾斜するよう、所定の長さにわたって形成されている。これにより、振動、現像スリーブ（１５）の内部に設けられた図示しない磁石の磁力分布のむら、現像剤（２２）中の部分的なトナー濃度の上昇等が発生した際に、第２ドクターブレード（２３）と現像スリーブ（１５）の周面との間から現像剤収容部（１６ａ）内のキャリアが落下しても、落下したキャリアは対向面（１４ｂ）で受けられて現像スリーブ（１５）側に移動し、磁力で現像スリーブ（１５）に磁着されて再び現像剤収容部（１６ａ）内に供給される。これにより現像剤収容部（１６ａ）内のキャリア量の減少を防止することができ、画像形成時における、現像スリーブ（１５）の軸方向での画像濃度むらの発生を防止することができる。対向面（１４ｂ）の傾斜角度（α）としては５゜程度が、また、所定の長さ（ｌ）としては、好ましくは２〜２０ｍｍ、さらに好ましくは３〜１０ｍｍ程度が望ましい。
【００７２】
上記構成により、トナーホッパー（１９）の内部からトナーアジテータ（２１）によって送り出されたトナー（１８）は、トナー供給開口部（２０）を通って現像スリーブ（１５）に担持された現像剤（２２）に供給され、現像剤収容部（１６ａ）へ運ばれる。そして、現像剤収容部（１６ａ）内の現像剤（２２）は、現像スリーブ（１５）に担持されて感光体ドラム（１）の外周面と対向する位置まで搬送され、トナー（１８）のみが感光体ドラム（１）上に形成された静電潜像と静電的に結合することにより、感光体ドラム（１）上にトナー像が形成される。
【００７３】
ここで、上記トナー像形成時における現像剤（２２）の挙動を説明する。現像装置（１３）に磁性キャリア（２２ａ）のみからなるスタート剤をセットすると、図２に示すように、磁性キャリア（２２ａ）は現像スリーブ（１５）の表面に磁着されるものと現像剤収容部（１６ａ）内に収容されるものとに分かれる。現像剤収容部（１６ａ）内に収容された磁性キャリア（２２ａ）は、現像スリーブ（１５）の矢印（ａ）方向への回転に伴い、現像スリーブ（１５）内からの磁力によって矢印（ｂ）方向へ循環移動する。そして、現像スリーブ（１５）の表面に磁着された磁性キャリア（２２ａ）の表面と現像剤収容部（１６ａ）内で移動する磁性キャリア（２２ａ）の表面との境界部において界面（Ｘ）が形成される。
【００７４】
次に、トナーホッパー（１９）にトナー（１８）がセットされると、トナー供給開口部（２０）より現像スリーブ（１５）に担持された磁性キャリア（２２ａ）にトナー（１８）が供給される。従って、現像スリーブ（１５）は、トナー（１８）と磁性キャリア（２２ａ）との混合物である現像剤（２２）を担持することとなる。
【００７５】
現像剤収容部（１６ａ）内では、収容されている現像剤（２２）の存在により、現像スリーブ（１５）によって搬送される現像剤（２２）に対して、その搬送を停止させようとする力が働いている。そして、現像スリーブ（１５）に担持された現像剤（２２）の表面に存在するトナー（１８）が界面（Ｘ）へ搬送されると、界面（Ｘ）近傍における現像剤（２２）間の摩擦力が低下して界面（Ｘ）近傍の現像剤（２２）の搬送力が低下し、これにより界面（Ｘ）近傍での現像剤（２２）の搬送量が減少する。
【００７６】
一方、合流点（Ｙ）より現像スリーブ（１５）の回転方向上流側の現像剤（２２）には、上述の現像剤収容部（１６ａ）内のような、現像スリーブ（１５）によって搬送される現像剤（２２）に対して、その搬送を停止させるような力は作用しないので、合流点（Ｙ）へ搬送されてきた現像剤（２２）と界面（Ｘ）を搬送される現像剤（２２）との搬送量のバランスが崩れて現像剤（２２）の玉突状態が発生し、合流点（Ｙ）の位置が上昇して界面（Ｘ）を含む現像剤（２２）の層厚が増加する。また、第１ドクターブレード（１７）を通過した現像剤（２２）の層厚も徐々に増加し、この増加した現像剤（２２）が第２ドクターブレード（２３）によって掻き落とされる。
【００７７】
そして、第１ドクターブレード（１７）を通過した現像剤（２２）が所定のトナー濃度に達すると、図２に示すように、第２ドクターブレード（２３）に掻き落とされて層状となった増加分の現像剤（２２）がトナー供給開口部（２０）を塞ぎ、この状態でトナー（１８）の取り込みが終了する。このとき、現像剤収容部（１６ａ）内では、トナー濃度が高くなることにより現像剤（２２）の嵩が大きくなり、これにより現像剤収容部（１６ａ）内の空間が狭くなることによって、現像剤（２２）が図の矢印（ｂ）方向に循環移動する移動速度も低下する。
【００７８】
このトナー供給開口部（２０）を塞ぐように形成された現像剤（２２）の層において、第２ドクターブレード（２３）に掻き落とされた現像剤（２２）は、移動して対向面（１４ｂ）で受けられるが、対向面（１４ｂ）が現像スリーブ（１５）側に向けて角度（α）で下方に傾斜し、かつ、所定長さ（ｌ）を有しているため、現像剤（２２）の層の移動による、トナーホッパー（１９）への現像剤（２２）の落下を防止することができ、現像剤（２２）の量を常に一定に保つことができるので、トナー供給を常時一定に自己制御することが可能となる。
【００７９】
【実施例】
次に、本実施例等に用いるカーボン処理磁性体の製造例を示す。これは公知の表面処理手段により得ることができるが、これに限定されない。
【００８０】
（黒色化された磁性体製造例１）
戸田工業社製のマグネタイト粒子ＭＴＳ−３０５に、カーボンブラックを８ｗｔ％メカノミル（岡田精工社製）またはメカノフュージョンシステム（ホソカワミクロン社製）を用いてマグネタイト粒子表面に固定させ黒色磁性体１を得た。
【００８１】
（黒色化された磁性体製造例２）
戸田工業社製のマグネタイト粒子ＭＴＳ−３０５に、アニリンブラックを８ｗｔ％メカノミル（岡田精工社製）またはメカノフュージョンシステム（ホソカワミクロン社製）を用いてマグネタイト粒子表面に固定させ黒色磁性体２を得た。
【００８２】
次に、本実施例等に用いるシリコーン樹脂を被覆層に有するキャリアの製造例を示す。これは公知の手段により行なうことができる。
（キャリア製造例１）
被覆層形成液の組成
シリコン樹脂溶液（ＳＲ２４１１ 東レシリコーン社製） １００部
カーボンブラック（＃４４ 三菱化成工業社製） ４部
トルエン １００部
上記処方をホモミキサーで３０分間分散して被覆層形成液を調製した。この被覆層形成液を平均粒径８０μｍの球状フェライト１０００重量部の表面に流動床型塗布装置を用いて被覆層を形成したキャリアＡを得た。
【００８３】

上記組成の混合物をヘンシェルミキサー中で十分撹拌混合した後、ロールミルで１３０〜１４０℃の温度で約３０分間加熱溶融し、室温まで冷却後、得られた混練物をジェットミルまたは機械式粉砕機、風力分級機で粉砕分級し、体積平均径９．０μｍのトナー母体を得た。得られたトナー母体に所定の疎水性シリカを０．７ｗｔ％添加混合し、最終的なトナーとした。このトナー４．０部に対し、上記キャリアＡ９６．０部とをボールミルで混合し現像剤を得た。この現像剤にＭＦ−２５０を用いて複写実験を行なった。
なお、このときのトナーの飽和磁化は１５．２ｅｍｕ／ｇ、分子量分布のメインピークは１００００、トナー分子量分布の半値幅は３０００００、ＴＨＦ不溶分は０％であった。
【００８４】
（実施例２）
トナー体積平均径を１２．０μｍ、疎水性シリカ添加量を０．５ｗｔ％とした以外は、実施例１と同様なトナーを得た。
【００８５】
（実施例３）
トナー体積平均径を７．０μｍ、疎水性シリカ添加量を０．９ｗｔ％とした以外は、実施例１と同様なトナーを得た。
【００８６】
（比較例１）
実施例１中のカーボン処理磁性体１をカーボン未処理品に変えた以外は、実施例１と同様な試験を行なった。
【００８７】
（比較例２）
実施例１中のカーボン処理磁性体１を５ｗｔ％、カーボンブラックを１０ｗｔ％含有させた以外は、実施例１と同様な試験を行なった。なお、このときのトナーの飽和磁化は５．８ｅｍｕ／ｇであった。
【００８８】
（比較例３）
実施例１中のカーボン処理磁性体１を５０ｗｔ％含有させた以外は、実施例１と同様な試験を行なった。なお、このときのトナーの飽和磁化は４１．８ｅｍｕ／ｇであった。
【００８９】
（実施例４）
実施例１の磁性体量を３６ｗｔ％に増やした以外は、実施例１と同様な試験を行なった。なお、このときのトナーの飽和磁化は３１．２ｅｍｕ／ｇであった。
【００９０】
（実施例５）
実施例１の磁性体粒径を０．１３μｍのものに代えた以外は、実施例１と同様な試験を行なった。このときのトナーの飽和磁化は１６．２ｅｍｕ／ｇであった。
【００９１】
（実施例６）
実施例１の磁性体粒径を０．３５μｍのものに代えた以外は、実施例１と同様な試験を行なった。このときのトナーの飽和磁化は１５．０ｅｍｕ／ｇであった。
【００９２】

上記組成の混合物をヘンシェルミキサー中で十分撹拌混合した後、ロールミルで１３０〜１４０℃の温度で約３０分間加熱溶融し、室温まで冷却後、得られた混練物をジェットミルまたは機械式粉砕機、風力分級機で粉砕分級し、体積平均粒径約９μｍのトナー母体を得た。得られたトナー母体に所定の疎水性シリカを０．７ｗｔ％添加混合し、最終的なトナーとした。このトナー４．０部に対し、上記キャリアＡ９６．０部とをボールミルで混合し現像剤を得た。この現像剤を用いて実施例１と同様な試験を行なった。
なお、このときのトナーの飽和磁化は１３．６ｅｍｕ／ｇ、分子量分布のメインピークは７９００、トナー分子量分布の半値幅は１３０００、ＴＨＦ不溶分は１８％であった。
【００９３】
（実施例８）
実施例１と同様なトナー１３．０部に対し、上記キャリアＡ８７．０部とをボールミルで混合し現像剤を得た。この現像剤に前記構成中に示した図１、２の装置を搭載したＭＦ−２００改造機を用いて複写実験を行なった。
【００９４】
（比較例４）
実施例８中の黒色磁性体１をカーボン未処理品に変えた以外は、実施例８と同様な試験を行なった。
【００９５】
（比較例５）
実施例８中のカーボンブラックを８ｗｔ％に増加含有させた以外は、実施例８と同様な試験を行なった。
なお、このときのトナーの飽和磁化は１２．３ｅｍｕ／ｇであった。
【００９６】
（比較例６）
実施例８中の黒色磁性体１を５ｗｔ％、カーボンブラックを１０ｗｔ％含有させた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は５．４ｅｍｕ／ｇであった。
【００９７】
（比較例７）
実施例８中の黒色磁性体１を５０ｗｔ％含有させた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は４１．８ｅｍｕ／ｇであった。
【００９８】
（実施例９）
実施例８でカーボンブラックを除いたトナーを用いた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は２１．９ｅｍｕ／ｇであった。
【００９９】
（実施例１０）
実施例８の磁性体量を３８ｗｔ％に増やした以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は３１．３ｅｍｕ／ｇであった。
【０１００】
（実施例１１）
実施例８の磁性体粒径を０．１３μｍのものに代えた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は１３．８ｅｍｕ／ｇであった。
【０１０１】
（実施例１２）
実施例８の磁性体粒径を０．３５μｍのものに代えた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は１３．２ｅｍｕ／ｇであった。
【０１０２】
（実施例１３）
実施例８のトナーを以下の構成に代えた以外は、実施例８と同様な試験を行なった。
ポリエステル樹脂（Ａ） ５０部
（重量平均分子量５，１００、Ｔｇ６３℃、ＴＨＦ不溶分０％、
軟化点１４５℃、分子量ピーク４，１００）
ポリエステル樹脂（Ｂ） ５０部
（重量平均分子量６，２００、Ｔｇ６１℃、ＴＨＦ不溶分３０％、
軟化点１００℃、分子量ピーク３，８００）
酸化ライスワックス ５部
黒色磁性体２（平均径０．２５μｍ） ３０部
（２２．１ｗｔ％）
含金属アゾ化合物 １部
上記組成の混合物をヘンシェルミキサー中で十分撹拌混合した後、ロールミルで１３０〜１４０℃の温度で約３０分間加熱溶融し、室温まで冷却後、得られた混練物をジェットミルまたは機械式粉砕機、風力分級機で粉砕分級し、体積平均粒径約６．８μｍのトナー母体を得た。得られたトナー母体に所定の疎水性シリカを０．７ｗｔ％添加混合し、最終的なトナーとした。このトナー４．０部に対し、上記キャリアＡ９６．０部とをボールミルで混合し現像剤を得た。この現像剤を用いて実施例６と同様な試験を行なった。
なお、このときのトナーの飽和磁化は１７．３ｅｍｕ／ｇ、分子量分布のメインピークは６１００、トナー分子量分布の半値幅は１００００、ＴＨＦ不溶分は１３％であった。
【０１０３】
（実施例１４）
実施例１３の黒色着色剤２を黒色着色剤１に代えた以外は、実施例８と同様な試験を行なった。なお、このときのトナーの飽和磁化は１７．１ｅｍｕ／ｇであった。
【０１０４】
【発明の効果】
以上、詳細かつ具体的な説明から明らかなように、磁性体表面が着色剤により被覆処理により黒色化された磁性体を所定の範囲内でトナー中に含有させることにより、地かぶりが改良されたトナーを提供することができ、また、トナー供給を常時一定に自己制御することができる簡易な構成でトナー濃度の調整を容易に行なうことができる特定の現像方式に用いるトナーにおいて、磁性体表面が着色剤の被覆処理により黒色化された磁性体を含有させることによりコピー経時で濃度ムラ、地かぶりが改良された画像形成方法及び画像形成装置を提供することができるるという極めて優れた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の画像形成装置の１例を示す図である。
【図２】本発明の画像形成装置例におけるトナー像形成時の現像剤の挙動を示す例である。
【符号の説明】
１ 潜像担持体（感光体ドラム）
１３ 現像装置
１４ 支持ケース
１４ａ 支持ケース突出部
１４ｂ 支持ケース対向面
１４ｃ トナーエンドセンサ
１５ 現像剤担持体（現像スリーブ）
１６ 現像剤収容部材
１６ａ 現像剤収容部
１７ 第１の規制部材（第１ドクターブレード）
１８ トナー
１９ トナー収容部（トナーホッパー）
２０ トナー供給開口部
２１ トナー供給手段（トナーアジテータ）
２２ 現像剤
２２ａ 磁性キャリア
２３ 第２の規制部材（第２ドクターブレード）
Ｘ 界面部（界面）
Ｙ 現像剤合流点
ａ 現像スリーブ回転方向
ｂ キャリア循環方向
α 対向面傾斜角度
ｌ 対向面長さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming toner, an image forming method, and an image forming apparatus used for electrophotography, electrostatic printing, and the like.
[0002]
[Prior art]
In the dry two-component developer used in the two-component development method, fine toner particles are held on the surface of relatively large particles by the electric force generated by friction between both particles, and when close to the electrostatic latent image, The attracting force in the direction of the latent image with respect to the toner particles due to the electric field force formed by the electrostatic latent image overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered onto the electrostatic latent image. The latent image is visualized. The developer is repeatedly used while replenishing the toner consumed by the development.
[0003]
Conventionally, toners used in two-component developers are mainly non-magnetic toners using carbon black as a colorant. However, when used over time, the amount of charge is reduced due to the deterioration of the carrier as a charging member. However, when reversely charged or weakly charged toner is generated, there is a problem that ground fog is likely to occur. As a countermeasure, a method has been devised in which a magnetic substance is contained and a ground bias is prevented by using a magnetic bias. However, since there is no image density if the magnetic substance amount is large, there is a range of an appropriate magnetic substance amount. It was. In addition, the magnetic material alone when the amount of the magnetic material is small is insufficient in terms of coloring degree, and it is necessary to use it together with carbon black. However, a large amount of carbon black is contained for the purpose of improving the coloring degree. And there was a problem such as a decrease in the ground cover margin.
[0004]
As a fixing method in electrophotography, a heated heat roller method is widely used because of its energy efficiency. Further, as in recent low-temperature fixing and high-speed copying for energy saving, the thermal energy given to the toner at the time of fixing tends to be small. In general, attempts have been made to improve the low-temperature fixability of the toner used for such low-temperature fixing by using a resin or wax having a low softening point. However, since such a low-temperature fixing toner is thermally weak, it is known to cause so-called blocking, which is hardened by the heat of the machine used or the heat during storage. In addition, it is difficult to secure a sufficient fixing temperature range, and even if a polyester resin, which is said to be relatively good in heat storage for good low-temperature fixability, a toner that still solves this problem can be obtained. Not.
[0005]
In order to solve these problems, several methods using two types of polyester resins having different characteristics have been proposed. For example, JP-A-60-90344 discloses mixing a non-linear polyester resin and a linear polyester resin, and JP-A 64-15755 discloses a softening point of Tg 50 ° C. or higher. It is disclosed that a cross-linked polyester resin having a temperature of 200 ° C. or lower and a linear polyester resin having a softening point of 150 ° C. or lower and a MW of 3,000 to 50,000 are mixed. It is disclosed that a non-linear polymer polyester resin having a dispersion ratio of 20 or more and a non-linear polyester resin having a MW of 1,000 to 5,000 and a dispersion ratio of 4 or less is disclosed in JP-A-3-229264. The publication discloses that an organometallic compound comprising a linear polyester resin having an acid value of 5 to 60 and a non-linear polyester resin having an acid value of less than 5 is contained. Are, in JP-A-3-41470, the ratio of acid value with a saturated polyester resin is disclosed to mix a 1.5 or more different polyester resins.
[0006]
However, in recent years, low-temperature fixing has been increasingly progressed, and further low-temperature fixing has been demanded. Together with downsizing of the device, securing low-temperature fixability and fixing temperature range when using a low-load fixing device and heat storage It is becoming difficult to achieve both.
Further, in this two-component development method, in order to obtain a stable image density, it is necessary to make the mixing ratio (toner density) of the carrier and the toner constant, and it is necessary to mount a toner replenishing mechanism and a sensor for that purpose. In addition, the developing device becomes large and its operation mechanism is complicated.
[0007]
On the other hand, in the one-component development method, unlike the two-component development method, a developer in which carrier particles and toner particles are mixed is not used, and an electric force generated by friction between the toner and the developing sleeve or a toner and a magnet containing a magnetic material are used. When the toner is held on the developing sleeve by the magnetic force between the built-in developing sleeves and the electrostatic latent image is brought close to the electrostatic latent image, the toner particles and the developing sleeve are attracted to the latent image by the electric field formed by the electrostatic latent image. Overcoming the bonding force between the toner particles, the toner particles are attracted onto the electrostatic latent image to visualize the electrostatic latent image.
Therefore, since it is not necessary to control the toner density in the one-component development method, there is an advantage that the developing device can be downsized. However, since the number of toner particles in the development region is smaller than that in the two-component development method, The toner was not sufficiently supplied to the printer, making it difficult to handle high-speed copying machines.
[0008]
On the other hand, there is known a developing device that uses a two-component developer and does not require a toner density detecting means and takes in toner by the movement of the developer. However, in this developing device, the amount of toner taken in is different between a portion where the developer is actively moving and a portion where the developer is not moving, or a portion where the developer is high and a portion where the developer is low, and the toner density is partially unstable. Concentration unevenness and ground fog are likely to occur. Therefore, a technology that solves density unevenness and fogging in the longitudinal direction of the apparatus by disposing two toner supply members in the toner hopper and allowing the developer to pass through a path formed by each toner supply member. This is disclosed in Japanese Utility Model Publication No. 63-4282. However, since the technique disclosed in the above publication uses two toner supply members, there is a problem that the developing unit becomes large and the cost increases. Further, Japanese Patent Laid-Open No. 9-197833 discloses a technique for solving the above-mentioned drawbacks, but it is not sufficient for eliminating the density unevenness described above.
[0009]
In recent years, the demand for high-quality images has increased in the market, and it has become impossible to obtain a sufficiently high image quality with a conventional toner having a volume average particle size of 10 to 15 μm. Further, a toner having a smaller particle size is required. ing.
[0010]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above prior art, and aims to provide the toner for forming an electrostatic image of the present invention. Further, by reducing the number of parts and consolidating functions, the present invention can be reduced in size and size. An object of the present invention is to provide an image forming method and apparatus capable of obtaining a high-quality image while reducing costs.
[0011]
[Means for Solving the Problems]
The inventors of the present invention have intensively studied that the toner having at least a binder resin and magnetic powder contains 10 to 40 wt% of a magnetic material whose surface is coated with a colorant and blackened. The present inventors have found that the above disadvantages can be eliminated.
Here, the use of carbon black, which is one of the causes of ground fogging, can be eliminated or reduced by including in the toner a magnetic material whose surface has improved jetness by coating with a colorant. In addition, since the responsiveness due to the bias of the toner having a small charge amount such as a low charge amount and a reverse charge amount can be lowered by the magnetic bias effect, a margin such as a ground cover can be further improved. Here, when the amount of the magnetic material is less than 10 wt%, the effect of improving the ground cover by the magnetic bias effect is low, and when it is more than 40 wt%, the magnetic bias effect is too large and the developing ability is extremely lowered, and the image density is reduced. There was a problem with this point.
[0012]
The colorant used for the blackening is preferably a pigment or / and a dye. Further, since the color pigment is carbon black in particular, there is an advantage that a black magnetic material having a high jetness can be obtained, and that a desired black can be easily obtained by coating a small amount of the magnetic material.
[0013]
Moreover, it discovered that the said fault can be eliminated by containing 10-30 wt% of the magnetic body by which this magnetic powder was coat | covered with carbon black more preferably.
[0014]
Further, when the toner contains carbon black therein, the carbon black content needs to be 6 wt% or less. Here, when the carbon black content is more than 6 wt%, the occurrence of ground cover due to the carbon black content is observed, and the smaller the content, the more the ground cover is improved. At most, 6 wt% is the limit value. When not contained, the ground cover was the best. It is better not to contain it.
[0015]
Further, when the average particle size of the magnetic particles is 0.20 to 0.40 μm, preferably 0.2 to 0.30 μm, the dispersibility of the magnetic material in the resin is appropriately dispersed, and carbon black As a substitute for a black colorant such as the above, a coloring degree can be obtained. Here, when the thickness is less than 0.2 μm, the aggregation of the magnetic substance in the resin is more likely to occur, the occurrence of ground fogging due to poor dispersion is seen, and when it is larger than 0.40 μm, there is a problem in terms of coloring degree. was there.
[0016]
Further, the saturation magnetization value of the toner is preferably in the range of 10 emu / g to 25 emu / g, more preferably in the range of 12 emu / g to 22 emu / g. Here, when the value of the saturation magnetization is less than 10 emu / g, the effect of improving the ground cover by the magnetic bias effect is low. When the saturation magnetization value is more than 25 emu / g, the magnetic bias effect is too large and the developing ability is extremely reduced, and the image There was a defect in terms of concentration.
[0017]
Further, the binder resin is mainly a polyester resin, and the molecular weight distribution value by GPC determined from the THF soluble content of the toner has at least one peak between 1000 and 10,000. It has been found that when the full width at half maximum is 15,000 or less and the toner contains 2 to 40% of a THF-insoluble content, a toner that can be fixed at a low temperature and has no problem of background staining can be obtained.
[0018]
The particle size of the toner of the present invention is not particularly limited, but the volume average particle size is preferably 2.5 to 10 μm in order to obtain a high image quality excellent in fine line reproducibility and the like. In particular, when a specific magnetic material such as that used in the present invention is contained in the toner, the toner is easily pulverized at the time of pulverization at the time of toner production, and the toner has a smaller particle size. For this reason, it becomes easy to obtain high image quality.
[0019]
Here, the volume average particle diameter of the toner can be measured by various methods. In the present invention, Coulter Counter TAII manufactured by Coulter Electronics, USA is used.
[0020]
Further, by using a two-component developer containing a toner and a magnetic carrier, the contact state between the developer and the toner is changed by changing the toner concentration of the developer on the developer carrier, and the developer In a developing device that changes the toner intake state of a developer on a carrier, the toner has at least a binder resin and magnetic powder, and the surface of the magnetic powder is coated with a colorant and blackened. It has been found that the above-mentioned drawbacks can be solved by an image forming method characterized by using a body. In general, when magnetic toner is used in two-component development, unlike single-component development, if magnetic toner with high magnetization like that used in ordinary magnetic one-component developer is used, the development ability is different due to the difference in development. However, there is a problem that the desired image density cannot be obtained. In addition, in order to solve this problem, when a toner having a reduced magnetic substance content and a reduced magnetization is used, a desired image density can be obtained even with two-component development. When black pigment such as carbon black used in the conventional two-component toner is included in order to improve the blackness, the degree of blackness is lowered, and the margin against ground fog is lowered.
[0021]
In particular, in the image forming method that does not require the toner density detecting means of the present invention, density unevenness and ground fogging are observed as compared with the two-component development that has a conventional toner density detecting means and can maintain an appropriate toner density. There is a need to improve the margin for occurrence.
[0022]
The colorant used for the blackening is preferably a pigment or / and a dye. Further, since the color pigment is carbon black in particular, there is an advantage that a black magnetic material having a high jetness can be obtained, and that a desired black can be easily obtained by coating a small amount of the magnetic material.
Furthermore, the developer is changed in contact state between the developer and the toner by changing the toner concentration of the developer on the developer carrier using a two-component developer containing toner and a magnetic carrier. The toner used in the developing device that changes the toner intake state of the developer on the carrier has at least a binder resin and magnetic powder, and the surface of the magnetic powder is coated with a colorant and blackened. It has been found that by using a magnetic material, an image forming apparatus capable of eliminating the above-mentioned drawbacks can be provided.
[0023]
As a specific example of the image forming apparatus of the present invention, a developer carrier having a magnetic field generating means therein and carrying and transporting a two-component developer containing toner and a magnetic carrier, and the developer carrier A first regulating member that regulates the amount of the developer carried by the body, a developer containing unit that contains the developer scraped off by the first regulating member, and the developer containing unit A toner container for supplying toner to the developer carrier, and changing the contact state between the developer and the toner by changing the toner concentration of the developer on the developer carrier. And a developing device that changes a toner intake state of the developer on the developer carrying member, wherein the developer containing portion is in a transport direction of the developer on the developer carrying member rather than the first regulating member. A second restricting member disposed on the upstream side; The regulating member is configured to regulate the passage of the developer when the toner density of the developer on the developer carrying body increases and the layer thickness of the developer increases. A developer is set in the developer container, and the developer in the developer container moves in the developer container regardless of a change in the toner density of the developer on the developer carrier. When the toner density of the developer on the developer carrier becomes a predetermined toner density, the developer whose passage is restricted by the second restriction member is the developer on the developer carrier and the toner. The toner used in the developing device that stops the toner taking-in state of the developer on the developer carrying member by blocking the contact portion with the developer is a binder resin and magnetic powder. At least, the surface of the magnetic powder is coated with a colorant and black Image forming apparatus and the like to use a magnetic material that is of.
[0024]
The improvement in density unevenness in the image device is to make the toner easily move in the lateral direction. The larger the restraining force on the toner restrained by the magnetic force on the developing sleeve, the harder the toner moves, and the density unevenness. Was more prominent. Accordingly, the lower the restraining force on the toner, the better, and it is necessary to set the magnetic force of the toner itself within a specific range in order to achieve both the suppression of the ground cover by the magnetic bias and the density unevenness. However, in order to control the magnetic force of the toner, it is only necessary to control the amount of magnetic material contained in the toner. However, if the amount of magnetic material is made lower than a level generally called magnetic toner, the coloring power decreases. In addition, when the coloring power was supplemented by containing carbon black, the ground cover margin was lowered as described above. Here, by adding a magnetic material whose surface is coated with a colorant and blackened to the toner, a desired coloring degree can be obtained even when only a small amount of the magnetic material is used, and the above-described density unevenness and ground cover are compatible. I found out that I can do well.
[0025]
Further, it has been found that in the image forming apparatus, when the toner contains 10 to 40 wt% of a magnetic substance, more preferably 15 to 25 wt%, the above disadvantage can be solved. Here, when the amount of the magnetic material is less than 10 wt%, the effect of improving the ground cover by the magnetic bias effect is low, and when it is more than 40 wt%, the magnetic bias effect is too large and the developing ability is extremely lowered, and the image density is reduced. There was a problem with this point.
[0026]
In the image forming apparatus, the colorant used for the blackening is preferably a pigment or / and a dye.
[0027]
In particular, since the color pigment is carbon black, a black magnetic material having a high jetness can be obtained, and a desired black can be easily obtained by coating a small amount of the magnetic material.
[0028]
Further, it has been found that the above-mentioned drawbacks can be eliminated by containing 10 to 30 wt% of the magnetic material in which the magnetic powder is coated with carbon black in the image forming apparatus.
[0029]
Furthermore, in the image forming apparatus, when the toner contains carbon black inside, the content of carbon black needs to be 6 wt% or less. Here, when the carbon black content is more than 6 wt%, the occurrence of ground cover due to the carbon black content is seen, the smaller the content, the better the ground cover, and at most 6 wt% is the limit value. When it was not contained, the ground cover was the best. It is better not to contain it.
[0030]
Further, in the image forming apparatus, when the average particle diameter of the magnetic particles is 0.20 to 0.40 μm, the dispersibility of the magnetic material in the resin is moderately dispersed, and the black colorant carbon black It is possible to obtain a degree of coloring as a substitute for. Here, when the thickness is less than 0.2 μm, the aggregation of the magnetic substance in the resin is more likely to occur, and the occurrence of ground fogging due to poor dispersion is observed, and when it is larger than 0.4 μm, there is a problem in the degree of coloring. was there.
[0031]
Furthermore, in the image forming apparatus, the saturation magnetization value of the toner is preferably in the range of 10 emu / g to 25 emu / g, and more preferably in the range of 12 emu / g to 22 emu / g. Here, when the value of the saturation magnetization is less than 10 emu / g, the effect of improving the ground cover by the magnetic bias effect is low. When the saturation magnetization value is more than 25 emu / g, the magnetic bias effect is too large and the developing ability is extremely reduced, and the image There was a defect in terms of concentration.
[0032]
Furthermore, in the image forming apparatus, the binder resin is mainly a polyester resin, and at least one peak is obtained when the molecular weight distribution value by GPC obtained from the THF soluble content of the toner is 1000 to 10,000. And having a molecular weight of 15,000 or less and a toner content of 2 to 40% of THF insolubles, it has been found that a toner that can be fixed at a low temperature and has no problem of background staining can be obtained. .
[0033]
Furthermore, in the image forming apparatus, the particle size of the toner is not particularly limited, but in order to obtain a high image quality with excellent fine line reproducibility, the volume average particle size is 2.5 to 10 μm. preferable. In particular, when a specific magnetic material such as that used in the present invention is contained in the toner, the toner is easily pulverized at the time of pulverization at the time of toner production, and the toner has a smaller particle size. For this reason, it becomes easy to obtain high image quality.
[0034]
GPC (gel permeation chromatography) is measured as follows.
Stabilize the column in a heat chamber at 40 ° C., flow THF at a flow rate of 1 ml / min through the column at this temperature, and prepare a THF sample solution of resin prepared at a sample concentration of 0.05 to 0.6% by weight. Is measured by injecting 50 to 200 μl. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of the calibration curve prepared from several monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Or the molecular weight made by Toyo Soda Industry Co., Ltd. is 6 × 10 ² 2.1 × 10 ^Three 4 × 10 ^Three 1.75 × 10 ^Four 5.1 × 10 ^Four 1.1 × 10 ^Five 3.9 × 10 ^Five 8.6 × 10 ^Five 2 × 10 ⁶ 4.48 × 10 ⁶ It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
[0035]
The THF insoluble matter is measured as follows.
About 1.0 g of binder resin is weighed, about 50 g of THF is added thereto, and the mixture is allowed to stand at 20 ° C. for 24 hours. This is first separated by centrifugation and filtered at room temperature using JIS standard (P3801) type 5 C quantitative filter paper. Subsequently, the amount of filter paper residue (insoluble content) is measured, and the ratio (% by weight) between the toner used and the filter paper residue is calculated. When measuring the THF-insoluble content in the binder resin when it is used as a toner, about 1.0 g of toner is weighed out in the same manner as the binder resin. Therefore, it is obtained separately by thermal analysis.
The Tg of the binder resin is measured with a Rigaku THRMOFLEX TG8110 manufactured by Rigaku Corporation at a temperature increase rate of 10 ° C./min.
The softening point of the binder resin is an elevated flow tester CFT-500 (manufactured by Shimadzu Corporation), with a die diameter of 1 mm and a pressure of 20 kg / cm. ² 1 cm under the condition of a heating rate of 6 ° C./min ² Measured at a temperature corresponding to ½ from the outflow start point to the outflow end point when the sample was melted out.
[0036]
Next, materials used for the toner of the present invention will be described in detail.
Examples of the binder resin used in the present invention include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers of substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer. Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene -Vinyl methyl ether copolymer, styrene-bi Ruethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic Examples thereof include styrenic copolymers such as acid ester copolymers.
[0037]
Moreover, the following resin can also be mixed and used.
Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic Or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be mentioned.
[0038]
In addition, examples of the binder resin particularly suitable for pressure fixing include the following, which can be used in combination.
Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-butadiene copolymer (monomer ratio 5-30: 95-70), olefin copolymer (ethylene -Acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer Resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and the like.
[0039]
The method for producing these resins is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used. Further, the glass transition temperature Tg of the resin is preferably 55 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of heat storage stability.
[0040]
Furthermore, the magnetic material contained in the magnetic toner of the present invention includes iron oxides such as magnetite, hematite and ferrite, metals such as iron, cobalt and nickel, or aluminum, cobalt, copper, lead, magnesium and tin of these metals. And alloys of metals such as zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof.
In particular, magnetite is preferable in terms of magnetic properties. In the present invention, those obtained by coating the surfaces of these magnetic materials with a colorant are used. Here, the surface treatment with the colorant is a method of fixing the colorant on the surface of the magnetic material by a method using a mixer or the like for a magnetic material, a high-speed impact method, a dry mechanochemical method, or a polysiloxane as a paste. However, the method is not limited to these. The amount of carbon treated on the surface of the magnetic material is 5 to 20 wt%, more preferably 8 to 15 wt%, based on the weight of the magnetic material. In particular, the magnetic material used is more preferably spherical. In addition, the average particle diameter was calculated | required by the average value of 50 measured at random from the scanning electron micrograph.
[0041]
As the colorant used for coating the surface of the magnetic material of the present invention, for example, black dyes such as carbon black, lamp black, iron black, aniline black, graphite, fullerene, etc. A dye / pigment / compound that causes the appearance of the colorant and any conventionally known black dye / pigment can be used singly or in combination. Carbon black is most advantageous in terms of blackness. In consideration of the color of the magnetic material, a coloring agent that blackens the redness by a complementary color, for example, a blue dyeing pigment such as aniline blue or phthalocyanine blue may be used.
Regarding the blackness of the toner using the blackened magnetic material of the present invention, the color space L ^* Expressed as ab value, but L ^* The upper limit of the value is 24.0, preferably 23.0 or less, more preferably 21.0 or less, and the a value and the b value are each ± 1.5 or less, more preferably ± 1.0 or less. It is good to be. L ^* When the value exceeds 24.0, the brightness increases and the blackness decreases. About a value and b value, when it becomes larger than +/- 1.5, it will become the direction away from black in color space, and blackness will fall. Where L ^* The ab value was determined by measuring a solid image formed on paper with X-Rite 938 manufactured by X-Rite.
[0042]
Examples of the colorant used in the toner of the present invention include carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6C lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, Any conventionally known dyes such as rose bengal and triallylmethane dyes can be used alone or in combination, and can be used as a black toner or a full color toner. The amount of these colorants to be used is usually 1 to 30% by weight, preferably 3 to 20% by weight, based on the toner resin component.
[0043]
In the present invention, all known release agents for use in the toner can be used, and in particular, de-free fatty acid type carnauba wax, montan wax and oxidized rice wax can be used alone or in combination.
[0044]
As the carnauba wax, those having fine crystallinity, an acid value of 5 or less, and a particle diameter of 1 μm or less when dispersed in a toner binder are preferable. The montan wax generally refers to a montan wax refined from minerals, and like a carnauba wax, it is microcrystalline and preferably has an acid value of 5 to 14. The oxidized rice wax is obtained by air-oxidizing rice bran wax, and the acid value is preferably 10-30. As other mold release agents, any conventionally known mold release agents such as solid silicone varnish, higher fatty acid higher alcohol, montan ester wax, and low molecular weight polypropylene wax can be mixed and used. The amount of these release agents used is 1 to 20 parts by weight, preferably 3 to 10 parts by weight, based on the toner resin component.
[0045]
The toner of the present invention can be blended with a charge control agent, a fluidity improving agent, and the like as required.
In addition, as the charge control agent contained in the toner of the present invention, all conventionally known charge control agents can be used. Examples of positive charge control agents include nigrosine, basic dyes, lake dyes of basic dyes, quaternary ammonium salt compounds, etc., and examples of negative charge control agents include metal salts of monoazo dyes, salicylic acid, naphthoic acid, dyes, and the like. Examples include carboxylic acid metal complexes and the like.
[0046]
Moreover, as the hydrophobic inorganic fine powder used in the present invention, all known ones can be used, but hydrophobic silica fine powder, hydrophobic titanium fine powder and the like are preferable. Moreover, all the known hydrophobic silica particles used in the present invention can be used. Examples of hydrophobizing agents such as silane coupling agents, silicone varnishes, silicone oils, organosilicon compounds, and those having functional groups include hexamethyldisilazane, hexamethylenedisilazane, trimethylsilane, and trimethylchlorosilane. , Trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, benzyldimethylchlorosilane, chloromethyldimethylchlorosilane, dichlorodimethylsilane, triorganosilylmercaptan, trimethylsilylmercaptan, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, Diphenyldiethoxysilane, aminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropy Trimethoxysilane, dibutyl aminopropyl dimethoxysilane, there is trimethoxysilyl -γ- propylphenyl amine. Examples of the silicone oil include methyl silicone oil, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, amino-modified silicone oil, and polyoxyalkyl-modified silicone oil. These may be used alone or as a mixture of two or more. In the processes as described above, a single process or various processes may be used in combination.
[0047]
Moreover, all the well-known thing can be used for the hydrophobic titanium particle used by this invention. Surface treatment agents include various silicone oils such as methyl hydrogen polysiloxane, dimethyl polysiloxane, and methylphenyl polysiloxane, methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, and decyltrimethoxy. Various alkylsilanes such as silane, octadecyltrimethoxysilane, dimethyldimethoxysilane, octyltriethoxysilane, n-octadecyldimethyl (3- (trimethoxysilyl) propyl) ammonium chloride, trifluoromethylethyltrimethoxysilane, heptadecafluorodecyl Various fluoroalkyl silanes such as trimethoxysilane, in particular, silane couplers such as vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane. Silane-titanium-based, aluminum-based, alumina represented by a coupling agent - it can be either of the processing agent of each metal based coupling agent zirconia such use, and these in combination of two or more.
[0048]
Further, the toner of the present invention may be mixed with additives as necessary. Examples of additives include lubricants such as Teflon and zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidity imparting agents such as colloidal silica and aluminum oxide, anti-caking agents, or carbon black and tin oxide. And a fixing aid such as a low molecular weight polyolefin.
[0049]
The toner of the present invention can be used as a one-component toner or a two-component toner, and can also be used as a mono-black toner or a full-color black toner.
[0050]
The carrier core particles used when the toner of the present invention is used as a two-component developer include magnetic core particles consisting essentially of a magnetic material such as magnetic ferrite, and a large number of magnetic fine particles in the resin. It is divided into the case of dispersed magnetic substance dispersed resin core particles.
In the case of magnetic core particles, the magnetic material forming the core particles includes magnetic metals such as iron, nickel, cobalt and alloys thereof, or alloys containing rare earths; hematite, magnetite, manganese-zinc ferrite , Nickel-zinc ferrites, manganese-magnesium ferrites, soft ferrites such as lithium ferrites, iron-based oxides such as copper-zinc ferrites, and mixtures thereof.
[0051]
Furthermore, other iron-based alloys such as iron-silicon-based alloys, iron-aluminum-based alloys, iron-silicon-aluminum-based alloys, permalloy alloys, and the like can be used. Preferably, in the present invention, magnetic ferrite core particles, wherein the ferrite particles belong to periodic table IA, IIA, IIIA, IVA, VA, VIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIIIB Magnetic particles containing at least one element selected from the above and containing other elements of less than 1% by weight can be used.
[0052]
The magnetic core particles used in the present invention can be manufactured by a manufacturing method such as a sintering method or an atomizing method, and if necessary, granulate with a sharp particle size distribution of the magnetic material or a sintering temperature. By controlling the heating rate and the heating and holding time, magnetic core particles having predetermined magnetic properties can be produced.
[0053]
The specific resistance of the magnetic core particles used in the present invention can be used as long as it satisfies the desired magnetic properties. ^Five Ω · cm to 10 ^Ten Ferrite particles or magnetite particles having a specific resistance of Ω · cm are preferably used.
[0054]
In the case of magnetic material-dispersed resin core particles, examples of the magnetic material constituting the magnetic fine particles dispersed in the resin include alloys or compounds of ferromagnetic metals such as iron, cobalt, and nickel.
[0055]
Resin powders that can be coated on carrier core particles used when the toner of the present invention is used as a two-component developer include styrene-acrylic copolymer, silicone resin, maleic acid resin, fluorine resin, polyester resin, epoxy There are resins. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, if the styrene content is less than 30% by weight, the development characteristics are low, and if it exceeds 90% by weight, the coating film becomes hard and easily peeled, and the life of the carrier is shortened.
[0056]
Moreover, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive material, a charge control agent and the like in addition to the resin.
[0057]
When the toner of the present invention is used as either a one-component developer or a two-component developer, the toner is filled in a container, and the container filled with the toner is distributed separately from the image forming apparatus, and the user can It is common to form an image by mounting it on an image forming apparatus.
What is used as the container is not limited, and is not limited to the conventional bottle type or cartridge type.
[0058]
The image forming apparatus is not limited as long as it is an apparatus for forming an image by electrophotography, and includes, for example, a copying machine or a printer.
[0059]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. The developing device used was a MF-250 manufactured by Ricoh Co., Ltd. and a modified MF-200 equipped with the apparatus shown in FIGS. All parts are parts by weight. Table 1 shows the results obtained based on the evaluation shown below, which is the average of the evaluation results at the start of each example and after 140,000 sheets.
[0060]
(Ground cover)
A white document was output in A3 size, and the image density at arbitrary six positions of the image was measured with a Macbeth reflection densitometer, and the ID was determined in five stages according to the following criteria. The state where there is no ground cover is a value equivalent to the reflection density of paper, and the larger the value, the worse the ground cover.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil
[0061]
(Image density unevenness)
The degree of occurrence of image density unevenness (history of the immediately preceding image) after continuous output of 15 sheets of A4 size using a full-surface halftone chart was performed in five stages according to the following criteria.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil
[0062]
(Solid uniformity (image density))
Using an A3 size chart with 6 points of solid parts in the front, back, left, and right, an image is output in A3 size, and the image density at the position of the 6 solid parts of the image is measured with a Macbeth reflection densitometer. The ID deviation was determined in five stages according to the following criteria.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil
[0063]
(Fine line reproducibility)
Each developer was subjected to an image evaluation test, and the fine line reproducibility was evaluated in five stages according to the following criteria.
Excellent: ◎, Good: ○, □: Normal, △: Bad, ×: Worst
[0064]
(Fixability evaluation)
Ricoh Co., Ltd. Copier with a Teflon Roller as the Fixing Roller Using an apparatus with a modified MF-200 fixing unit, Ricoh type 6200 paper was set on this and a copy test was performed. The cold offset temperature (fixing lower limit temperature) and the hot offset temperature (hot offset resistant temperature) were determined by changing the fixing temperature. The minimum fixing temperature of the conventional low-temperature fixing toner is about 140 to 150 ° C. The evaluation conditions for low-temperature fixing are as follows: the paper feed linear velocity is 120 to 150 mm / sec, and the surface pressure is 1.2 kgf / cm. ² The evaluation conditions for the nip width 3 mm and the high temperature offset are as follows: the linear speed of paper feed is 50 mm / sec, and the surface pressure is 2.0 kgf / cm. ² The nip width was set to 4.5 mm.
The cold offset occurrence temperature and the high temperature offset occurrence temperature were determined as follows.
(Low temperature fixability)
Good ◎: Less than 130 ° C, ○: 130-140 ° C, □: 140-150 ° C,
Δ: 150-160 ° C., x: 160 ° C. or higher
(Hot offset)
Good ◎: 201 ° C or higher, ○: 200-191 ° C, □: 190-181 ° C,
Δ: 180-171 ° C., x: 170 ° C. or less
The five steps were performed.
[0065]
[Table 1]

[0066]
FIG. 1 is a schematic configuration diagram of a main part of a developing device of an image forming apparatus employing an embodiment of the developing device of the present invention. In an actual embodiment, this developing apparatus was incorporated into a modified machine obtained by modifying the Ricoh copier MF-200 for evaluation. The details will be described below.
The developing device (13) disposed on the side of the photosensitive drum (1) as a latent image carrier includes a support case (14), a developer sleeve (15) as a developer carrier, and a developer containing member ( 16) mainly composed of a first doctor blade (17) as a developer regulating member.
[0067]
The support case (14) having an opening on the side of the photosensitive drum (1) forms a toner hopper (19) as a toner storage portion for storing the toner (18) therein. A developer that forms a developer accommodating portion (16a) that accommodates a developer (22) composed of toner (18) and a carrier that is magnetic particles, near the photosensitive drum (1) side of the toner hopper (19). The housing member (16) is provided integrally with the support case (14). The support case (14) positioned below the developer accommodating member (16) is formed with a protrusion (14a) having a facing surface (14b), and a lower portion of the developer accommodating member (16). A toner supply opening (20) for supplying toner (18) is formed by the space between the opposing surface (14b).
[0068]
Inside the toner hopper (19), a toner agitator (21) is disposed as a toner supply means rotated by a drive means (not shown). The toner agitator (21) sends the toner (18) in the toner hopper (19) toward the toner supply opening (20) while stirring. Further, on the side of the toner hopper (19) facing the photosensitive drum (1), a toner end detecting means (for detecting when the amount of the toner (18) in the toner hopper (19) decreases) 14c) is arranged.
[0069]
A developing sleeve (15) is disposed in the space between the photosensitive drum (1) and the toner hopper (19). A developing sleeve (15) that is rotationally driven by a driving means (not shown) in the direction of the arrow in the figure is disposed therein so as not to change relative position with respect to the developing device (13). have.
A first doctor blade (17) is integrally attached to the developer accommodating member (16) on the side facing the side attached to the support case (14). The first doctor blade (17) is disposed in a state where a certain gap is maintained between its tip and the outer peripheral surface of the developing sleeve (15).
[0070]
A second doctor blade (23) as a restricting member is disposed in a portion of the developer accommodating member (16) located in the vicinity of the toner supply opening (20). The second doctor blade (23) is a layer of a developer (22) formed on the surface of the developing sleeve (15) so that the free end thereof maintains a certain gap with respect to the outer peripheral surface of the developing sleeve (15). A direction in which the flow is hindered, that is, the free end is directed to the center of the developing sleeve (15), and the base end is integrally attached to the developer containing member (16).
The developer accommodating portion (16a) is configured to have a sufficient space to circulate and move the developer (22) as long as the magnetic force of the developing sleeve (15) reaches.
[0071]
The opposing surface (14b) is formed over a predetermined length so as to incline downward from the toner hopper (19) side toward the developing sleeve (15) side. As a result, when vibration, uneven magnetic distribution of a magnet (not shown) provided in the developing sleeve (15), a partial increase in toner concentration in the developer (22), or the like occurs, the second doctor blade ( 23) and the peripheral surface of the developing sleeve (15), even if the carrier in the developer accommodating portion (16a) falls, the dropped carrier is received by the opposing surface (14b) and is on the developing sleeve (15) side. And is magnetically attached to the developing sleeve (15) by a magnetic force and is supplied again into the developer accommodating portion (16a). As a result, it is possible to prevent a decrease in the amount of carrier in the developer accommodating portion (16a), and it is possible to prevent the occurrence of uneven image density in the axial direction of the developing sleeve (15) during image formation. The inclination angle (α) of the opposing surface (14b) is about 5 °, and the predetermined length (l) is preferably about 2 to 20 mm, more preferably about 3 to 10 mm.
[0072]
With the above configuration, the toner (18) sent out from the inside of the toner hopper (19) by the toner agitator (21) passes through the toner supply opening (20), and the developer (22) carried on the developing sleeve (15). ) And is carried to the developer accommodating portion (16a). The developer (22) in the developer accommodating portion (16a) is carried on the developing sleeve (15) and conveyed to a position facing the outer peripheral surface of the photosensitive drum (1), and only the toner (18) is transferred. A toner image is formed on the photosensitive drum (1) by electrostatically coupling with the electrostatic latent image formed on the photosensitive drum (1).
[0073]
Here, the behavior of the developer (22) during the toner image formation will be described. When a starting agent consisting only of a magnetic carrier (22a) is set in the developing device (13), as shown in FIG. 2, the magnetic carrier (22a) is magnetically attached to the surface of the developing sleeve (15) and contains the developer. It is divided into what is accommodated in a part (16a). The magnetic carrier (22a) accommodated in the developer accommodating portion (16a) is moved by the magnetic force from the developing sleeve (15) as the developing sleeve (15) rotates in the arrow (a) direction. Cycle in the direction. An interface (X) is present at the boundary between the surface of the magnetic carrier (22a) magnetically attached to the surface of the developing sleeve (15) and the surface of the magnetic carrier (22a) moving in the developer accommodating portion (16a). It is formed.
[0074]
Next, when the toner (18) is set in the toner hopper (19), the toner (18) is supplied from the toner supply opening (20) to the magnetic carrier (22a) carried on the developing sleeve (15). . Therefore, the developing sleeve (15) carries the developer (22) which is a mixture of the toner (18) and the magnetic carrier (22a).
[0075]
In the developer accommodating portion (16a), a force for stopping the conveyance of the developer (22) conveyed by the developing sleeve (15) due to the presence of the accommodated developer (22). Is working. When the toner (18) existing on the surface of the developer (22) carried on the developing sleeve (15) is conveyed to the interface (X), the friction between the developers (22) in the vicinity of the interface (X). The force decreases and the transport force of the developer (22) in the vicinity of the interface (X) decreases, thereby reducing the transport amount of the developer (22) in the vicinity of the interface (X).
[0076]
On the other hand, the developer (22) upstream of the developing sleeve (15) in the rotation direction from the junction (Y) is conveyed by the developing sleeve (15) as in the developer accommodating portion (16a). Since the developer (22) does not have a force to stop the conveyance, the developer (22) conveyed to the junction (Y) and the developer (22) conveyed through the interface (X). ) Is unbalanced and the developer (22) is struck, the junction (Y) is raised, and the layer thickness of the developer (22) including the interface (X) is increased. To do. Further, the layer thickness of the developer (22) that has passed through the first doctor blade (17) gradually increases, and the increased developer (22) is scraped off by the second doctor blade (23).
[0077]
Then, when the developer (22) that has passed through the first doctor blade (17) reaches a predetermined toner concentration, as shown in FIG. 2, it is scraped off by the second doctor blade (23) and increases in layers. Minute developer (22) closes the toner supply opening (20), and in this state, the toner (18) is completely taken up. At this time, in the developer accommodating portion (16a), the toner density is increased, so that the bulk of the developer (22) is increased, and the space in the developer accommodating portion (16a) is thereby narrowed. The moving speed at which the agent (22) circulates in the direction of the arrow (b) in the figure also decreases.
[0078]
In the developer (22) layer formed so as to close the toner supply opening (20), the developer (22) scraped off by the second doctor blade (23) moves to the opposite surface (14b). However, since the opposing surface (14b) is inclined downward at an angle (α) toward the developing sleeve (15) and has a predetermined length (l), the developer (22) ) To prevent the developer (22) from dropping into the toner hopper (19) due to the movement of the layer, and the amount of the developer (22) can be kept constant, so that the toner supply is always constant. It becomes possible to self-control.
[0079]
【Example】
Next, an example of producing a carbon-treated magnetic material used in this example and the like is shown. This can be obtained by known surface treatment means, but is not limited thereto.
[0080]
(Blackened magnetic material production example 1)
Carbon black was fixed to the magnetite particles MTS-305 manufactured by Toda Kogyo Co., Ltd. on the surface of the magnetite particles using 8 wt% Mechano Mill (Okada Seiko Co., Ltd.) or Mechano Fusion System (Hosokawa Micron Co., Ltd.) to obtain a black magnetic body 1.
[0081]
(Blackened magnetic material production example 2)
The black magnetic body 2 was obtained by fixing aniline black to the magnetite particle MTS-305 manufactured by Toda Kogyo Co., Ltd. on the surface of the magnetite particle using 8 wt% Mechano Mill (Okada Seiko Co., Ltd.) or Mechano Fusion System (Hosokawa Micron Co., Ltd.).
[0082]
Next, the manufacture example of the carrier which has the silicone resin used for a present Example etc. in a coating layer is shown. This can be done by known means.
(Carrier production example 1)
Composition of coating layer forming solution
100 parts of silicone resin solution (SR2411 manufactured by Toray Silicone Co., Ltd.)
Carbon black (# 44 manufactured by Mitsubishi Chemical Industries) 4 parts
100 parts of toluene
The above formulation was dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. Carrier A in which the coating layer was formed on the surface of 1000 parts by weight of spherical ferrite having an average particle size of 80 μm by using a fluidized bed coating apparatus was obtained from this coating layer forming liquid.
[0083]

The mixture having the above composition is sufficiently stirred and mixed in a Henschel mixer, heated and melted at a temperature of 130 to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, and the obtained kneaded product is jet mill or mechanical pulverizer, By pulverizing and classifying with an air classifier, a toner base having a volume average diameter of 9.0 μm was obtained. The final toner was prepared by adding 0.7 wt% of predetermined hydrophobic silica to the obtained toner base. To 4.0 parts of the toner, 96.0 parts of the carrier A were mixed with a ball mill to obtain a developer. A copying experiment was conducted using MF-250 as the developer.
At this time, the saturation magnetization of the toner was 15.2 emu / g, the main peak of the molecular weight distribution was 10,000, the half width of the toner molecular weight distribution was 300000, and the THF insoluble content was 0%.
[0084]
(Example 2)
A toner similar to that of Example 1 was obtained except that the toner volume average diameter was 12.0 μm and the amount of hydrophobic silica added was 0.5 wt%.
[0085]
(Example 3)
A toner similar to that of Example 1 was obtained except that the toner volume average diameter was 7.0 μm and the amount of hydrophobic silica added was 0.9 wt%.
[0086]
(Comparative Example 1)
The same test as in Example 1 was performed except that the carbon-treated magnetic body 1 in Example 1 was changed to a carbon-untreated product.
[0087]
(Comparative Example 2)
A test similar to that of Example 1 was performed, except that 5 wt% of the carbon-treated magnetic material 1 and 10 wt% of carbon black in Example 1 were contained. At this time, the saturation magnetization of the toner was 5.8 emu / g.
[0088]
(Comparative Example 3)
The same test as in Example 1 was performed except that 50 wt% of the carbon-treated magnetic material 1 in Example 1 was contained. At this time, the saturation magnetization of the toner was 41.8 emu / g.
[0089]
(Example 4)
The same test as in Example 1 was performed except that the amount of magnetic material in Example 1 was increased to 36 wt%. At this time, the saturation magnetization of the toner was 31.2 emu / g.
[0090]
(Example 5)
A test similar to that of Example 1 was performed except that the particle diameter of the magnetic material in Example 1 was changed to 0.13 μm. The saturation magnetization of the toner at this time was 16.2 emu / g.
[0091]
(Example 6)
A test similar to that of Example 1 was performed, except that the magnetic particle diameter of Example 1 was changed to that of 0.35 μm. The saturation magnetization of the toner at this time was 15.0 emu / g.
[0092]

The mixture having the above composition is sufficiently stirred and mixed in a Henschel mixer, heated and melted at a temperature of 130 to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, and the obtained kneaded product is jet mill or mechanical pulverizer, By pulverizing and classifying with an air classifier, a toner base having a volume average particle size of about 9 μm was obtained. The final toner was prepared by adding 0.7 wt% of predetermined hydrophobic silica to the obtained toner base. To 4.0 parts of the toner, 96.0 parts of the carrier A were mixed with a ball mill to obtain a developer. Using this developer, the same test as in Example 1 was performed.
At this time, the saturation magnetization of the toner was 13.6 emu / g, the main peak of the molecular weight distribution was 7900, the full width at half maximum of the toner molecular weight distribution was 13000, and the THF insoluble content was 18%.
[0093]
(Example 8)
A developer was obtained by mixing 13.0 parts of the toner similar to Example 1 with 87.0 parts of the carrier A by a ball mill. A copying experiment was conducted on this developer using a modified MF-200 equipped with the apparatus shown in FIGS.
[0094]
(Comparative Example 4)
A test similar to that in Example 8 was performed except that the black magnetic body 1 in Example 8 was changed to a carbon-untreated product.
[0095]
( Comparative Example 5 )
The same test as in Example 8 was performed except that the carbon black in Example 8 was increased to 8 wt%.
At this time, the saturation magnetization of the toner was 12.3 emu / g.
[0096]
( Comparative Example 6 )
A test was performed in the same manner as in Example 8 except that 5 wt% of the black magnetic material 1 and 10 wt% of carbon black in Example 8 were contained. At this time, the saturation magnetization of the toner was 5.4 emu / g.
[0097]
( Comparative Example 7 )
The same test as in Example 8 was performed, except that 50 wt% of the black magnetic material 1 in Example 8 was included. At this time, the saturation magnetization of the toner was 41.8 emu / g.
[0098]
(Example 9 )
A test similar to that in Example 8 was performed, except that the toner excluding carbon black was used in Example 8. At this time, the saturation magnetization of the toner was 21.9 emu / g.
[0099]
(Example 10 )
The same test as in Example 8 was performed except that the amount of magnetic material in Example 8 was increased to 38 wt%. At this time, the saturation magnetization of the toner was 31.3 emu / g.
[0100]
(Example 11 )
A test similar to that of Example 8 was performed except that the particle diameter of the magnetic material in Example 8 was changed to 0.13 μm. At this time, the saturation magnetization of the toner was 13.8 emu / g.
[0101]
(Example 12 )
A test similar to that of Example 8 was performed, except that the magnetic substance particle size of Example 8 was changed to 0.35 μm. At this time, the saturation magnetization of the toner was 13.2 emu / g.
[0102]
(Example 13 )
A test similar to that of Example 8 was performed, except that the toner of Example 8 was changed to the following configuration.
50 parts of polyester resin (A)
(Weight average molecular weight 5,100, Tg 63 ° C., THF insoluble content 0%,
(Softening point 145 ° C, molecular weight peak 4,100)
50 parts of polyester resin (B)
(Weight average molecular weight 6,200, Tg 61 ° C., THF insoluble content 30%,
(Softening point 100 ° C, molecular weight peak 3,800)
5 parts of oxidized rice wax
Black magnetic material 2 (average diameter 0.25 μm) 30 parts
(22.1wt%)
Metal-containing azo compound 1 part
The mixture having the above composition is sufficiently stirred and mixed in a Henschel mixer, heated and melted at a temperature of 130 to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, and the obtained kneaded product is jet mill or mechanical pulverizer, By pulverizing and classifying with an air classifier, a toner base having a volume average particle size of about 6.8 μm was obtained. The final toner was prepared by adding 0.7 wt% of predetermined hydrophobic silica to the obtained toner base. To 4.0 parts of the toner, 96.0 parts of the carrier A were mixed with a ball mill to obtain a developer. A test similar to that of Example 6 was performed using this developer.
At this time, the saturation magnetization of the toner was 17.3 emu / g, the main peak of the molecular weight distribution was 6100, the full width at half maximum of the toner molecular weight distribution was 10,000, and the THF insoluble content was 13%.
[0103]
(Example 14 )
Example 13 Black colorant 2 The black colorant 1 A test similar to that of Example 8 was performed except that is replaced with. At this time, the saturation magnetization of the toner was 17.1 emu / g.
[0104]
【The invention's effect】
As described above, as is clear from the detailed and specific description, the ground cover has been improved by including in the toner a magnetic body whose magnetic surface has been blackened by a coating treatment with a colorant within a predetermined range. In a toner used in a specific developing system that can easily adjust toner density with a simple configuration that can provide toner and that can always self-control toner supply constantly, the surface of the magnetic material is By including a magnetic material that has been blackened by coating with a colorant, it is possible to provide an image forming method and an image forming apparatus in which density unevenness and ground fog are improved over time. Is.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention.
FIG. 2 is an example showing the behavior of a developer during toner image formation in an example of the image forming apparatus of the present invention.
[Explanation of symbols]
1 Latent image carrier (photosensitive drum)
13 Development device
14 Support case
14a Support case protrusion
14b Support case facing surface
14c Toner end sensor
15 Developer carrier (developing sleeve)
16 Developer accommodating member
16a Developer container
17 First restriction member (first doctor blade)
18 Toner
19 Toner container (toner hopper)
20 Toner supply opening
21 Toner supply means (toner agitator)
22 Developer
22a Magnetic carrier
23 Second regulating member (second doctor blade)
X interface (interface)
Y Developer confluence
a Development sleeve rotation direction
b Carrier circulation direction
α Opposite surface inclination angle
l Opposite surface length

Claims (12)

Using a two-component developer containing toner and a magnetic carrier, the contact state between the developer and the toner is changed by changing the toner density of the developer on the developer carrier, and the developer carrier An image forming method using a developing device that changes the toner intake state of the developer of
The toner contains 10 to 40 wt% of at least a binder resin and a blackened magnetic material whose surface is coated with a colorant , and the amount of the magnetic surface carbon black treated is 5 with respect to the weight of the magnetic material. The image forming method according to claim 1, further comprising: 3/140 wt% or less of carbon black in addition to the magnetic surface carbon black. The image forming method according to claim 1, characterized by containing 10 to 30 wt% of a magnetic material coated with the carbon black. The image forming method according to claim 1 or 2 average particle size of the magnetic particles are characterized by a 0.20～0.40Myuemu. Wherein a binder resin is mainly a polyester resin, the values of molecular weight distribution by GPC determined by THF-soluble matter of the toner has at least one peak between 1,000 to 10,000, the half value width of該分cloth a molecular weight of 15,000 or less, the image forming method according to any one of claims 1 to 3, characterized in that the toner contains a THF-insoluble matter 2-40%. The toner electrostatic image forming toner according to any one of claims 1 to 4, wherein the volume average particle diameter of 2.5～10Myuemu. Using a two-component developer containing toner and a magnetic carrier, the contact state between the developer and the toner is changed by changing the toner density of the developer on the developer carrier, and the developer carrier An image forming apparatus using a developing device that changes the toner intake state of the developer of
The toner contains 10 to 40 wt% of at least a binder resin and a blackened magnetic material whose surface is coated with a colorant , and the amount of the magnetic surface carbon black treated is 5 with respect to the weight of the magnetic material. An image forming apparatus, characterized in that it is ˜20 wt% and may contain 3/140 wt% or less of carbon black in addition to the magnetic surface carbon black. The image forming apparatus according to claim 6, characterized by containing 10 to 30 wt% of a magnetic material coated with the carbon black. The electrostatic image forming apparatus according to claim 6, wherein the magnetic particles have an average particle diameter of 0.20 to 0.30 μm. Wherein a binder resin is mainly a polyester resin, the values of molecular weight distribution by GPC determined by THF-soluble matter of the toner has at least one peak between 1,000 to 10,000, the half value width of該分cloth 9. The image forming apparatus according to claim 6 , wherein the toner has a molecular weight of 15,000 or less and the toner contains 2 to 40% of a THF-insoluble matter. The image forming apparatus according to claim 6, wherein the toner has a volume average particle diameter of 2.5 to 10 μm. The image forming method or toner container for an image forming apparatus toner is filled according to any of claims 1 to 10. An image forming apparatus to which the toner container according to claim 11 is mounted.

Images