JP3890143B2 - Magnetic toner for developing electrostatic image, manufacturing method thereof, image forming method and process cartridge - Google Patents

Description

（式中、ＭＸＬＮＧは粒子の絶対最大長、ＰＥＲＩＭＥは粒子の周囲、ＡＲＥＡは粒子の投影面積を示す。）
【００３５】
形状係数ＳＦ−１はトナー粒子の丸さの度合いを示し、形状係数ＳＦ−２はトナー粒子の凹凸の度合いを示している。
【００３６】
磁性トナー粒子は、より好ましくは形状係数ＳＦ−１とＳＦ−２の比（ＳＦ−１／ＳＦ−２）が１．０１〜１．２０であるのが良い。さらに好ましくは、磁性トナー粒子は、形状係数ＳＦ−１が１４５〜１６０であり、ＳＦ−２が１３５〜１５５であるのが良く、さらに、形状係数ＳＦ−１とＳＦ−２との比（ＳＦ−１／ＳＦ−２）が１．０５〜１．１５であるのが良い。
【００３７】
磁性トナー粒子に外添剤が外添されている磁性トナーのＳＦ−１及びＳＦ−２を測定しても、外添剤の粒径が非常に小さいか、又は、粒径の大きい外添剤の個数が少ないので磁性トナー粒子のＳＦ−１及びＳＦ−２と実質的に同じ値を一般に示す。
【００３８】
本発明の磁性トナーにおいては、７９５．８ｋＡ／ｍ（１０ｋエルステッド）の磁界下における磁性微粉体の残留磁化〔σ_r （Ａｍ² ／ｋｇ）〕と保磁力〔Ｈ_C （ｋＡ／ｍ）〕の積（σ_r ×Ｈ_C ）が２４〜５６（ｋＡ² ｍ／ｋｇ）であることが好ましい。
【００３９】
本発明の磁性トナーが好ましく用いられる現像方法として、トナー担持体内にマグネットが設置され、このマグネットで磁性トナーを保持し、トナー担持体上で摩擦帯電を行ない帯電した磁性トナーで静電荷像保持体の静電荷像を現像する方法が挙げられる。このような現像方法において、本発明の磁性トナーを構成する重量平均粒径３．５〜６．５μｍの磁性トナー粒子を用いた場合、低温・低湿環境下における、カブリ、耐久時におけるベタ黒濃度薄の現象及び高温・高湿環境下においてドラム融着現象が生じ易くなる。これらの問題は、磁性微粉体の磁気力（σ_r ×Ｈ_C ）をコントロールすることで効果的に解決することが可能となる。低温・低湿環境においては、摩擦帯電量が高くなった磁性トナーの現像を抑制可能な様に磁性トナーに磁気力を与えてやることで、画像濃度を維持し、カブリの発生をより良好に防止することができる。
【００４０】
さらに、トナー担持体表面に磁性トナーを適度に磁気的拘束力で拘束することでトナー担持体表面での磁性トナーの循環が良化し、低温・低湿環境における磁性トナーの過度のチャージアップが原因と考えられる耐久時におけるベタ黒濃度薄現象を防止することが可能となる。また、高温・高湿環境においても、摩擦帯電量の高い磁性トナー粒子が選択的に現像され易い。磁性トナー粒子の小径化が進行すればする程、ドラム融着現象が生じ易くなる。この場合においても摩擦帯電量の比較的高めの磁性トナー粒子の現像を抑制し得る磁気力を磁性トナーに与えることで防止可能となる。
【００４１】
σ_r ×Ｈ_C が２４未満の磁性微粉体を用いた場合には、磁気的拘束力が効果的に作用しないため、低温・低湿環境においてカブリやすく、耐久時のベタ黒濃度薄現象が生じ易く、高温・高湿環境においてはドラム融着現象が生じ易くなる。また、σ_r ×Ｈ_C が５６を超える場合には、逆に磁気的拘束力が支配的となり、全環境において画像濃度低下を招きやすいので好ましくない。より好ましい範囲としては、３０〜５２の場合である。本発明において、磁気特性はＶＳＭＰ−１−１０（東英工業社製）を用いて、外部磁場７９５．８ｋＡ／ｍで測定を行なった。
【００４２】
本発明の磁性トナーに用いられる磁性微粉体としては、鉄、コバルト、ニッケル、銅、マグネシウム、マンガン、アルミニウム、ケイ素の如き元素を含む磁性を有する金属酸化物がある。これらの磁性微粉体の個数平均粒径は好ましくは０．０５〜０．３０μｍであり、より好ましくは０．１０〜０．２５μｍである。個数平均粒径が０．０５μｍより小さい場合、磁性微粉体の色味が赤みを帯びる傾向にあり、磁性トナーの場合その色味が画像の色味に反映されるため好ましくない。また、個数平均粒径が０．３０μｍより大きい場合は、画像濃度とカブリのラチチュードが狭くなり、好ましくない。
【００４３】
また、本発明に用いられる磁性微粉体の構成する磁性微粒子の形状としては、八面体、六面体、球形が挙げられる。磁性微粒子の形状は球形のものが画像濃度とカブリのラチチュードを広くとり得るため好ましい。
【００４４】
さらに本発明の課題をより高度なレベルで満足させるためには、該磁性微粉体を構成する磁性微粒子は少なくとも表面に二酸化ケイ素を有し、その表面に存在させる二酸化ケイ素の重量％をＷ（％）、該磁性微粉体の個数平均粒径をＲ（μｍ）とした場合、Ｗ×Ｒが０．００３〜０．０４２を満足することが好ましい。以下、Ｗ×Ｒについて説明する。
【００４５】
（ａ）Ｗの測定方法：
▲１▼２Ｎ−ＮａＯＨ溶液で磁性微粉体を構成する磁性微粒子の表面に存在する二酸化ケイ素（ＳｉＯ₂ ）を溶出させる（４０℃、３０分間）。
▲２▼溶出前と溶出後の磁性微粉体中のＳｉＯ₂ 量を蛍光Ｘ線分析により測定する。
Ｗ（％）＝〔（溶出前のＳｉＯ₂ 量−溶出後のＳｉＯ₂ 量）／（溶出前の磁性微粉体の重量）〕×１００
【００４６】
（ｂ）Ｒの測定方法：
Ｒは、透過型電子顕微鏡で磁性粉微粉体を構成する磁性微粒子の写真を撮影し、４万倍に拡大したものにつき、任意に２５０個選定後、投影径の中のＭａｒｔｉｎ径（定方向に投影面積を２等分する線分の長さ）を測定し、測定値に基づいて個数平均粒径を算出する。
【００４７】
Ｗ×Ｒの値を規定することにより、磁性微粒子の表面におけるＳｉＯ₂ 存在状態が密であるか粗であるかの判別がより明確に把握される。
【００４８】
先ずここで、磁性微粉体の平均粒径から求められる比表面積をＳ、磁性微粉体の密度をρとすると、Ｓ＝４πＲ² ×〔１／（４／３）πＲ³ ・ρ〕＝３／Ｒ・ρとなる。上記の表面のＳｉＯ₂ の存在状態は、実際はＷ／Ｓ＝Ｒ・Ｗ・ρ／３で与えられる。Ｗ／Ｓの好ましい範囲は、０．００１ρ≦Ｗ／Ｓ≦０．０１４ρであるから、０．００１ρ≦Ｒ・Ｗ・ρ／３≦０．０１４ρとなり、式を簡略化すると、０．００３≦Ｗ×Ｒ≦０．０４２となる。
【００４９】
Ｗ×Ｒが０．００３より小さい場合は、磁性微粉体粒子の表面ＳｉＯ₂ の存在が非常にまばらな状態であるため、磁性トナーへの流動性付与効果が少なく、低温・低湿環境下において画像濃度低下、カブリの増加を招きやすい。Ｗ×Ｒが０．０４２より大きい場合は、混練時結着樹脂と磁性微粉体との濡れ性が低下し、トナー製造時に磁性トナー粒子から磁性微粉体が離脱し易くなり、この遊離した磁性微粉体を原因としたドラム融着が生じ易くなる。より好ましいＷ×Ｒの範囲は０．００８〜０．０３５である。
【００５０】
磁性トナー粒子中の磁性微粉体の含有量は４０〜６０重量％であることが好ましい。４０重量％より少ない場合は重量平均粒径３．５〜６．５μｍの磁性トナー粒子においては、カブリ現象の発生を抑制することが困難となり、６０重量％より多い場合は、画像濃度薄、帯電ローラ汚れ、ドラム融着が発生しやすくなる。より好ましくは、磁性トナー粒子中の磁性微粉体の含有量は、４５〜５５重量％が良い。
【００５１】
本発明の磁性トナーの磁性トナー粒子は、ワックスを含有している。ワックスとしては、パラフィンワックス及びその誘導体、マイクロクリスタリンワックス及びその誘導体、フィッシャートロプシュワックス及びその誘導体、ポリオレフィンワックス及びその誘導体、カルナバワックス及びその誘導体長鎖カルボン酸及びその誘導体，長鎖アルコール及びその誘導体が挙げられる。誘導体としては酸化物や、ビニル系モノマーとワックスとのブロック共重合物、ビニル系モノマーとワックスとのグラフト変性物を含む。
【００５２】
本発明で好ましく用いられるワックスは、一般式Ｒ−Ｙ（式中、Ｒは炭化水素基を示し、Ｙは水酸基、カルボキシル基、アルキルエーテル基、エステル基又はスルホニル基を示す。）式Ｒ−Ｙで示されるワックスのゲルパーミエーションクロマトグラフィ（ＧＰＣ）による重量平均分子量（Ｍｗ）が３０００以下であることが好ましい。
【００５３】
具体的な化合物例としては、下記のものが挙げられる。
（Ａ）ＣＨ₃ （ＣＨ₂ ）_n ＣＨ₂ ＯＨ（ｎ＝２０〜３００）
（Ｂ）ＣＨ₃ （ＣＨ₂ ）_n ＣＨ₂ ＣＯＯＨ（ｎ＝２０〜３００）
（Ｃ）ＣＨ₃ （ＣＨ₂ ）_n ＣＨ₂ ＯＣＨ₂ （ＣＨ₂ ）_m ＣＨ₃ （ｎ＝２０〜２００、ｍ＝０〜１００）
【００５４】
上記化合物（Ｂ）、（Ｃ）は化合物（Ａ）の誘導体であり、主鎖は直鎖状の飽和炭化水素である。上記化合物（Ａ）から誘導される化合物であれば、上記例に示した以外のものでも使用できる。特に好ましいワックスはＣＨ₃ （ＣＨ₂ ）_n ＯＨ（ｎ＝２０〜３００）で表わされる長鎖アルキルアルコール及びそれらの混合物を主成分とするものである。
【００５５】
この長鎖アルキルアルコールワックスを用いた場合、混練時における結着樹脂とワックスとの分散性が極めて良好である為に、従来の混練条件よりワックスの分散性を過度に考慮した混練条件を設定する必要がなくなり、結着樹脂と磁性微粉体との濡れ性を考慮した条件設定が可能となる。
【００５６】
一般的に従来の混練条件において、混練機から混練物が吐出した直後における混練温度が混練状態を知る重要なパラメーターである。長鎖アルキルアルコールワックスの軟化点に対して３０〜７０℃高い混練温度となる混練条件においてもワックスの結着樹脂への分散性は良好であり、かつこの様な場合においては、結着樹脂と磁性微粉体との濡れ性も良好となり、本発明の課題がより良好に達成できる。図３参照。
【００５７】
本発明の磁性トナーに使用される結着樹脂について以下に述べる。
【００５８】
本発明に使用されるトナーの結着樹脂としては、例えば、ポリスチレン；ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如きスチレン置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレンビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体の如きスチレン共重合体；ポリ塩化ビニル、フェノール樹脂、天然変性フェノール樹脂、天然変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニール、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロンインデン樹脂、石油系樹脂等が挙げられる。架橋されたスチレン系樹脂も好ましい結着樹脂である。
【００５９】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、アクリロニトリル、メタクリロニトリル、アクリルアミドのような二重結合を有するモノカルボン酸もしくはその置換体；マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチルのような二重結合を有するジカルボン酸及びその置換体：塩化ビニル、酢酸ビニル、安息香酸ビニルのようなビニルエステル；エチレン、プロピレン、ブチレンのようなエチレン系オレフィン；ビニルメチルケトン、ビニルヘキシルケトンのようなビニルケトン；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルのようなビニルエーテルが挙げられる。これらのビニル単量体が単独もしくは組合せてスチレンモノマーとともに用いられる。架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられる。例えば、ジビニルベンゼン、ジビニルナフタレンのような芳香族ジビニル化合物；エチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレートのような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホンの如きジビニル化合物；及び３個以上のビニル基を有する化合物が挙げられる。これら架橋剤は単独もしくは混合して使用される。
【００６０】
さらにスチレン系樹脂は、ゲルパーミェーションクロマトグラフィー（ＧＰＣ）において測定される分子量分布において、少なくとも分子量０．５×１０⁴ 〜５×１０⁴ 及び分子量１．０×１０⁵ 〜５．０×１０⁶ の領域にメインピーク及びサブピークを有する場合により好ましく用いられる。スチレン系樹脂は、テトラヒドロフラン（ＴＨＦ）の可溶成分の重量平均分子量（Ｍｗ）が、１．５×１０⁵ 〜３．５×１０⁵ 、より好ましくは１．８×１０⁵ 〜３．２×１０⁵ が良い。
【００６１】
本発明の磁性トナーには、荷電制御剤として有機金属化合物を用いることが好ましい。有機金属化合物のうちでも、特に気化性や昇華性に富む有機有機化合物を配位子や対イオンとして含有するものが有用である。
【００６２】
このような、有機金属化合物としては、次に示した一般式で表わされるアゾ系金属錯体がある。
【００６３】
【外２】

〔上記一般式中、Ｍは配位中心金属を表わし、配位数６のＣｒ、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ａｌ、Ｔｉ、Ｓｃ又はＶが挙げられる。Ａｒはアリール基であり、フェニル基又はナフチル基が挙げられる、置換基を有していてもよい。置換基としては、ニトロ基、ハロゲン基、カルボキシル基、アニリド基及び炭素数１〜１８のアルキル基又はアルコキシ基がある。Ｘ、Ｘ′、Ｙ及びＹ′は−Ｏ−、−ＣＯ−、−ＮＨ−又は−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。
【００６４】
【外３】

は水素イオン、ナトリウムイオン、カリウムイオン、アンモニウムイオン、脂肪族アンモニウムイオン或いはこれらの混合イオンを示す。〕
【００６５】
本発明に良好に使用される錯体の具体例を以下に示す。
【００６６】
【外４】

【００６７】
【外５】

【００６８】
【外６】

【００６９】
荷電制御剤は、磁性トナー１００重量部に対して０．２〜５重量部の範囲で添加されるのが好ましい。
【００７０】
磁性トナーにおいては、帯電安定性、現像性、流動性、耐久性向上のため、磁性トナー粒子に無機微粉体を外添することが好ましい。
【００７１】
無機微粉体としては、例えばシリカ微粉体、酸化チタン微粉体、アルミナ微粉体等が挙げられる。特に、ＢＥＴ法で測定した窒素吸着により比表面積が３０ｍ² ／ｇ以上（特に５０〜４００ｍ² ／ｇ）の範囲内の無機微粉体が良好な結果を与える。磁性トナー１００重量部に対して無機微粉体０．０１〜８重量部、好ましくは０．１〜５重量部使用するのが良い。
【００７２】
また、無機微粉体は、必要に応じ、疎水化、帯電性コントロールの目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他の有機ケイ素化合物の如き処理剤で処理されていることも好ましい。処理剤は２種類以上使用しても良い。特に、シリコーンオイルで表面処理されたシリカ微粉体が好ましい。
【００７３】
他の添加剤としては、例えばテフロン、ステアリン酸亜鉛、ポリフッ化ビニリデン、シリコーンオイル粒子（約４０％のシリカ含有）の如き滑剤が好適に用いられる。また、酸化セリウム、炭化ケイ素、チタン酸カルシウム、チタン酸ストロンチウムの如き研磨剤が好ましく用いられ、中でもチタン酸ストロンチウムが好ましい。また、ケーキング防止剤；カーボンブラック、酸化亜鉛、酸化アンチモン、酸化スズの如き導電性付与剤；磁性トナー粒子と逆極性の白色微粒子及び黒色微粒子を現像性向上剤として少量用いても良い。
【００７４】
次に、磁性トナーに使用される磁性トナー粒子の製造方法について説明する。
【００７５】
本発明に用いられる混練機としては、近年の磁性トナーの量産化に対応して、エクストルーダーを用いて混練することが好ましい。特に二軸エクストルーダーが品質安定性及び量産性の観点から好ましい混練機である。具体例としては、ＴＥＭ−１００Ｂ（東芝機械製），ＰＣＭ−８７（池貝鉄工製）等が挙げられる。
【００７６】
本発明において、磁性トナー粒子を生成するための溶融混練工程において、結着樹脂，磁性微粉体及びワックスを少なくとも有する混合物を、混練機により下記条件
２．２×１０³ ≦Ｅ／ε≦２．０×１０⁴
Ｅ＝ｋω² Ｔ，ε＝Ｆ／（πＤ² Ｌ）
〔式中、ωはスクリュー回転速度（ｍ／ｍｉｎ）を示し、Ｔが設定温度（Ｋ）を示し、Ｆは混合物の供給量（ｋｇ／ｍｉｎ）を示し、Ｄはシリンダー内径（ｍ）を示し、Ｌはスクリュー有効長（ｍ）を示し、πは円周率を示し、ｋは（Ｄ₀ ／Ｄ）² を示し、Ｄ₀ は０．１ｍである。〕
で溶融混練することが好ましい。
【００７７】
混練条件をＥ／εの値で規定したのは、混練時の結着樹脂と磁性微粉体を構成する磁性微粒子との濡れ性を判断できる指標として、有効な値であるからである。Ｅ／εが大きいと濡れ性が上がるといえる。Ｅは混練機のスクリューの回転速度ωの２乗の値と混練設定温度Ｔの積であり、混練機の混練エネルギーを表わす値とみなせる。ω² はスクリューの運動エネルギーと相関する値であり、設定温度Ｔは混練機が供給する熱エネルギーと相関する値である。原材料が混練機で混練される時の混練状態を物理量でとらえようとすれば、混練機から供給される運動エネルギーと熱エネルギーの総和と密接な関係があると考えられる。ここでω² Ｔと積にしたのは、混練状態の差をより明確に把握できるよう考慮したからである。
【００７８】
ｋは補正定数である。経験から濡れ性は、シリンダー内径が０．１ｍの混練機よりシリンダーの内径の小さい混練機の方が向上する傾向にあるからである。
【００７９】
ε＝Ｆ／（πＤ² Ｌ）は、Ｆが単位時間当りの原材料の供給量であり、πＤ² Ｌは混練機のシリンダー内の原料存在可能容積と相関を有する値である。εは原材料のシリンダー中の充満状態を表わしている。εが大ということは充満状態が高いということである。仮りに混練エネルギーが同じ場合に、εが大のものは、単位時間における単位重量あたりの混練エネルギーが減じる傾向にあり、実際、結着樹脂と磁性微粉体との濡れ性は低下する傾向にある。
【００８０】
以上述べた様にＥ／εは、重量平均粒径が３．５乃至６．５μｍの微細な磁性トナー粒子を生成するための混練状態を、混練条件の基本となるスクリューの回転速度，設定温度，吐出量及びシリンダーの内容積というパラメーターに注目し、混練エネルギーと混練機内においてそのエネルギーを与えられる原材料の充満度という２つの観点で規定したものである。
【００８１】
Ｅ／εが２．２×１０³ より小さい場合は、結着樹脂と磁性微粉体の濡れ性が低下して、粉砕工程で遊離の磁性微粉体が発生し易くなり、得られら磁性トナーは帯電ローラ汚れ，ドラム融着が生じ易くなる。Ｅ／εが２．０×１０⁴ より大きい場合は、結着樹脂とワックスとの分散性が低下する傾向にあり、低温・低温環境下のカブリが生じ易くなる。
【００８２】
混練条件に規定した各パラメーターの値の範囲は、使用されている混練機の機種を考慮して決められる。
【００８３】
ωはスクリュー回転速度（ｍ／ｍｉｎ）を示し、５〜５０の範囲で良好に用いられる。Ｔは設定温度（Ｋ）を示し、３３３〜５１３の範囲が良好に用いられる。Ｆは混合物の供給量（ｋｇ／ｍｉｎ）を示し、０．１５〜２５の範囲が良好に用いられる。Ｄはシリンダー内径（ｍ）を示し、０．０３〜０．２の範囲が良好に用いられる。Ｌはスクリュー有効長（ｍ）を示し、１．００〜４．００の範囲が良好に用いられる。πは円周率であり、ｋは（Ｄ₀ ／Ｄ）² を示し、Ｄ₀ は０．１〔ｍ〕である。さらに、Ｅ＝ｋω² Ｔの値は、好ましくは３．０×１０⁵ 乃至１６．０×１０⁵ が良く、混合物の供給量Ｆは好ましくは０．３０乃至１２．０（ｋｇ／ｍｉｎ）が良く、ε＝Ｆ／（πＤ² Ｌ）の値は好ましくは８５乃至１３０が良く、Ｅ／εの値は好ましくは２．５×１０³ 乃至１．５×１０⁴ が良い。
【００８４】
混練条件を設定する際、軸スクリューのニーディングパドル構成も様々な構成が考えられるが、好ましくはニーディング領域は、溶融が開始する領域と分散性を向上させる領域の２ヶ所設定される場合である。混練物は、従来知られている方法で圧延冷却、粗砕、ジェット気流による微粉砕、図７に示す多分割方式による分級が行なわれ磁性トナー粒子が得られる。磁性トナー粒子の磁性微粉体及びワックスの分散性については、多分割分級工程で得られる図７におけるＭ粉体磁性トナー粒子及びＦ粉体の分級微粉中の磁性微粉体量とワックス量を比較することで知ることができる。
【００８５】
ｉ）磁性微粉体の分散性
例えば密度計アキュピック１３３０（島津製作所（株））でＭ粉体の磁性トナー粒子の密度の値Ｍと、Ｆ粉体の分級微粉の密度の値Ｆとの比Ｆ／Ｍで分散状態を知ることが可能である。Ｆ／Ｍの値が１よりはずれるほど磁性微粉体を構成する磁性微粒子の結着樹脂への均一分散性が低下していると判断し得る。
【００８６】
ｉｉ）ワックスの分散性
示差走査熱量計（パーキンエルマー社製）で測定されるＤＳＣ曲線において、吸熱ピーク曲線とベースラインで囲まれる面積に関して、Ｍ粉体の磁性トナー粒子のＤＳＣ曲線から得られる面積の値Ｍと、Ｆ粉体の分級微粉のＤＳＣ曲線から得られる面積の値Ｆとの比Ｆ／Ｍよりワックスの結着樹脂への均一分散性を知ることが可能である。Ｆ／Ｍの値が１よりはずれるほど分散性が低下していると判断し得る。
【００８７】
本発明の磁性トナー粒子の調製に使用し得る気流式分級機の一例として図７（断面図）及び図８及び図９（斜視図）に示す形式の装置の一具体例として例示する。
【００８８】
気流式分級装置及びその装置を利用した風力分級システムにおいては、鉛直方向に対して好ましくはθ＝４５°以下の角度で設置されている原料供給ノズルの後端部に、高圧エアー導入管と粉体原料導入ノズルを具備し、粉体原料導入ノズルの上方に有する原料供給口から磁性トナー粒子となる粉体原料を供給し、供給された粉体原料は粉体原料導入口下部から高圧エアー導入管の外周より放射され、高圧エアーにのって加速されて良好に分散し、良好に分散された粉体原料を原料供給ノズルに供給できる。そして、分級域の形状を変更する場合には、分級域が拡大し、分級点を大幅に変更できると共に、分級エッジ先端付近での気流の乱れを発生させることなく分級点を精度良く調整できるものである。粉体原料供給部における粉体原料の吸引吐出の原理は、高圧エアー導入管からの高圧エアーの粉体原料供給ノズルにおける膨張減圧エゼクター効果による。
【００８９】
図７及び図８及び図９において、側壁１２２及び１２３は分級室の一部を形成し、分級エッジブロック１２４及び１２５は分級エッジ１１７及び１１８を具備している。分級エッジ１１７及び１１８は、軸１１７ａ及び１１８ａを中心にして、回動可能であり、分級エッジを回動して分級エッジ先端位置を変えることができる。各分級エッジブロック１２４及び１２５は上下に設置位置をスライドさせることが可能であり、それにともなってそれぞれのナイフエッジ型の分級エッジ１１７及び１１８も上下にスライドする。この分級エッジ１１７及び１１８により、分級室１３２の分級ゾーンは３分画されている。
【００９０】
粉体原料を導入するための原料供給口１４０を原料供給ノズル１１６の最後端部に有し、該原料供給ノズル１１６の後端部に高圧エアー導入管１４１と粉体原料供給部を有する粉体原料導入ノズル１４２とを有し且つ分級室１３２に開口部を有する原料供給ノズル１１６を側壁１２２の右側に設け、該原料供給ノズル１１６の右側接線の延長方向に対して長楕円弧を描いたコアンダブロック１２６が設置されている。分級室１３２の左側ブロック１２７は、分級室１３２の左側方向にナイフエッジ型の入気エッジ１１４を具備し、更に分級室１３２の左側には分級室１３２に開口する入気管１１４及び１１５を設けてある。入気管１１４及び１１５にはダンパーのごとき第１気体導入調節手段１２０及び第２気体導入調節手段１２１と静圧計１２８及び静圧計１２９を設けてある。
【００９１】
高速エアー導入管１４１に導入する高圧エアーの圧力は、通常の分級では１．０〜３．０Ｋｇ／ｃｍ² であるが、磁性トナー粒子の表面に付着している磁性微粒子を効率良く遊離させて除去するためには、高圧エアーの圧力は、３．０Ｋｇ／ｃｍ² よりも高く、好ましくは３．５乃至６．０Ｋｇ／ｃｍ² 、であるのが良い。分級エッジ１１７及び１１８及び入気エッジ１１９の位置は、磁性トナー粒子の種類及び所望の粒径により調節される。
【００９２】
分級室１３２の右側にはそれぞれの分画域に対応させて、分級室内に開口する排出口１１１、１１２及び１１３を有し、排出口１１１、１１２及び１１３にはパイプの如き連通手段が接続されており、それぞれにバルブ手段のごとき開閉手段を設けてよい。
【００９３】
原料供給ノズル１１６は直角筒部と角錐筒部とから成り、直角筒部の内径と角錐筒部の最も狭い箇所の内径の比を２０：１から１：１、好ましくは１０：１から２：１に設定すると、良好な導入速度から得られる。
【００９４】
以上のように構成してなる多分割分級域での分級操作は例えば次のようにして行なう。排出口１１１、１１２、１１３の少なくとも１つを介して分級室内を減圧し、分級室内に開口部を有する原料供給ノズル１１６中を高圧エアーと該減圧によって流動する気流によって、好ましくは流速５０〜３００ｍ／秒の速度で粉体を原料供給ノズル１１６を介して分級室に噴出する。
【００９５】
分級室に導入された粉体原料中の磁性トナー粒子はコアンダブロック１２６のコアンダ効果による作用と、その際流入する空気のごとき気体の作用とにより湾曲線１３０ａ、１３０ｂ、１３０ｃ等を描いて移動し、それぞれの粒子の粒径及び慣性力の大小に応じて、大きい粒子（粗粒子）は気流の外側（すなわち分級エッジ１１８の外側の第１分画）、中間の粒子は分級エッジ１１８と１１７の間の第２分画、小さい粒子は分級エッジ１１７の内側の第３分画に分級され、分級された大きい粒子からなるＧ粉体は排出口１１１より排出され、分級された中間の粒子からなるＭ粉体は排出口１１２より排出され、分級された小さい粒子からなるＦ粉体は排出口１１３よりそれぞれ排出される。
【００９６】
磁性トナー粒子の分級において、分級点は磁性トナー粒子が分級室１３２内へ飛び出す位置であるコアンダブロック１２６の下端部分に対する分級エッジ１１７及び１１８のエッジ先端位置によって主に決定される。さらに、分級点は分級気流の流量あるいは原料供給ノズル１６からの磁性トナー粒子の噴出速度等の影響を受ける。
【００９７】
気流式分級装置において、原料供給口１４０から粉体原料を供給し、供給された粉体原料は粉体原料導入口１４２下部から高圧エアー導入管１４１の外周より放射され、高圧エアー導入管１４１から噴出している高圧エアーに乗って加速されて良好に分散し、瞬時に原料供給ノズル１１６から分級室内へ導入され分級されて、分級機系外へ排出されるため、分級機へ導入される粉体原料は原料供給ノズル１１６から分級室内の導入口部位によって、個々の粒子の軌跡が撹乱せずに凝集粉が一次粒子まで分散された状態で推進力をもって飛翔することが重要である。原料供給ノズル１１６内から流動する粒子流は粉体原料を上部から導入するとき、原料供給ノズル１１６の開口部より側位にコアンダブロック１２６を具備している分級室１３２にトナー粒子流を導入すると、粒子の飛翔軌跡が乱れることなく粒子の大きさに応じて分散して粒子流が形成されるので、その流線に添った向きに分級エッジを移動させ、次いで分級エッジのエッジ先端位置を固定し、所定の分級点に設定することができる。この分級エッジ１１７及び１１８の移動に際し、分級エッジブロック１２４及び１２５との同時移動により、コアンダブロック１２６に沿って飛翔する粒子流の流れ方向にエッジの向きを沿わすことができる。
【００９８】
具体的には、図１２において、原料供給ノズル１１６の先端開口部１１６ａの側面部に対応するコアンダブロック１２６中の例えば位置Ｏを中心として、分級エッジ１１７の先端とコアンダブロック１２６の側面との距離Ｌ₄ 及び分級エッジ１１７の側面とコアンダブロック１２６の側面との距離Ｌ₁ は、分級エッジブロック１２４を位置決め部材１３３に沿って上下に移動させることで、位置決め部材１３４に沿って分級エッジ１１７を上下に移動させ、さらに分級エッジ１１７の先端を軸１１７ａを中心にして回動させることにより調節可能である。
【００９９】
同時に、分級エッジ１１８の先端とコアンダブロック１２６の側壁との距離Ｌ₅ 及び分級エッジ１１７の側面と分級エッジ１１８の側面との距離Ｌ₂ もしくは分級エッジ１１８の側面と側壁１２３の側面との距離Ｌ₃ は、分級エッジブロック１２５を位置決め部材１３８に沿って上下に移動させることで、位置決め部材１３６に沿って分級エッジ１１８を上下に移動させ、さらに分級エッジ１１８の先端を軸１１８ａを中心にして回動させることにより調整可能である。
【０１００】
原料供給ノズル１１６の先端開口部１１６ａの側面部にコアンダブロック１２６、分級エッジ１１７及び１１８を設置させ、かつ分級エッジブロック１２４または／及び分級エッジブロック１２５の設置位置の変更に伴って、分級室の分級域が拡大し、分級点を容易に且つ大幅に変更することができる。
【０１０１】
そのため、分級エッジ先端部による流れの乱れが防止でき、排出導管１１１ａ、１１２ａ及び１１３ａを介しての減圧による吸引流の流量を調節することで粒子の飛翔速度を増加させて分級域でのトナー粒子の分散をより向上させ、より高い粉塵濃度でもより良好な分級精度が得られ、製品の収率低下を防止できるだけでなく、同じ粉塵濃度でもより良好な分級精度と製品の収率の向上が可能になる。
【０１０２】
入気エッジ１１９の先端とコアンダブロック１２６の壁面との距離Ｌ₆ は、軸１１９ａを中心として入気エッジ１１９先端を回動させることにより調節可能であり、これにより、入気管１１４及び１１５からの気体の流入量及び流入速度を調節することで、分級点のさらなる調整が可能である。
【０１０３】
上記の設定距離は粉体原料の特性等に応じて適宜決定されるが、磁性トナー粒子の真密度が１．４ｇ／ｃｍ³ を越える非磁性トナー粒子のとき、該分級エッジをそれぞれ具備している設置位置の変更可能な分級エッジブロックの設置位置を下記条件
Ｌ₀ ＞０、Ｌ₁ ＞０、Ｌ₂ ＞０、Ｌ₃ ＞０ Ｌ₀ ＜Ｌ₃ ＜Ｌ₁ ＋Ｌ₂
〔式中Ｌ₀ は、原料供給ノズルの排出口の高さ径（ｍｍ）を示し、
Ｌ₁ は、中粉体群と微粉体群とに分画するための第１分級エッジ側面と、これに対峙するコアンダブロックの側面との距離（ｍｍ）を示し、
Ｌ₂ は、第１分級エッジの側面と、粗粉体群と中粉体群とに分画するための第２分級エッジの側面との距離（ｍｍ）を示し、
Ｌ₃ は、第２分級エッジの側面と、これに対峙する側壁の側面との距離（ｍｍ）を示す〕を満足するように設定することが好ましい。
【０１０４】
この条件を満足する場合は、シャープな粒度分布を有する磁性トナー粒子を効率良く得ることができる。
【０１０５】
気流式分級装置は、相互の機器をパイプのごとき連通手段で連結し、装置システムに組み込まれて使用される。そうした装置システムの好ましい例を図１２に示す。図１２に示す一体装置システムは、３分割分級機１（図７及び図８に示される分級装置）、定量供給機２０２、振動フィーダー２０３、捕集サイクロン２０４、２０５、２０６を連通手段で連結してなるものである。
【０１０６】
この装置システムにおいて、粉体は、適宜の手段により、定量供給機２０２に送り込まれ、ついで振動フィーダー２０３を介し、原料供給ノズル１１６により３分割分級機２０１内に導入される。導入に際しては、５０〜３００ｍ／秒の流速で３分割分級機２０１内に粉体を導入する。３分割分級機２０１の分級室を構成する大きさは通常〔１０〜５０ｃｍ〕×〔１０〜５０ｃｍ〕なので、粉体は０．１〜０．０１秒以下の瞬時に３種以上の粒子群に分級し得る。そして、３分割分級機２０１に、大きい粒子（粗粒子）、中間の粒子、小さい粒子に分級される。その後、大きい粒子は排出導管１１ａを通って、捕集サイクロン２０６で送られ回収される。中間の粒子は排出導管１１２ａを介して系外に排出され捕集サイクロン２０５で捕集される。捕集サイクロン２０４、２０５、２０６は粉体を原料供給ノズル１１６を介して分級室に吸引導入するための吸引減圧手段としての働きをすることも可能である。
【０１０７】
図４を参照しながら本発明の磁性トナーを使用する画像形成方法の一例について説明する。
【０１０８】
接触帯電手段２は、バイアス印加手段Ｅにより電圧を印加され、静電荷像保持体（感光ドラム）１の表面を負極性に帯電し、レーザー光による露光３によりイメージスキャニングによりデジタル潜像を形成し、弾性ブレード６及び磁石を内包しているトナー担持体（現像スリーブ）５を具備する現像器４の磁性トナー１３で、該潜像を反転現像する。現像部において感光ドラム１の導電性基体は接地され、現像スリーブ５にはバイアス印加手段８により交互バイアス，パルスバイアス及び／又は直流バイアスが印加されている。
【０１０９】
転写紙Ｐが搬送されて転写部にくると、ローラ転写手段９により転写紙Ｐの背面（感光ドラム側と反対面）から電圧印加手段１０で帯電することにより、感光ドラム１の表面上の現像画像（トナー像）がローラ転写手段９によって転写紙Ｐ上に転写される。感光ドラム１から分離された転写紙Ｐは、加熱加圧ローラ定着器１２により転写紙Ｐ上のトナー画像を定着するために定着処理される。
【０１１０】
転写工程後の感光ドラム１に残留する磁性トナーが少ない場合、クリーニング工程を省くことが可能である。クリーニング手段１１によるクリーニング後の感光ドラム１は、再度、接触帯電手段２による帯電工程から始まる工程が繰り返される。
【０１１１】
感光ドラムは感光層及び導電性基体を有し、矢印方向に動く。トナー担持体である非磁性円筒の現像スリーブ５は、現像部において感光ドラム１の表面と同方向に進むように回転する。現像スリーブ５の内部には、磁界発生手段である多極永久磁石（マグネットロール）が回転しないように配されている。現像器４内の磁性トナー１３は非磁性円筒面上に塗布され、かつ現像スリーブ５の表面と磁性トナーとの摩擦によって、磁性トナーは、例えばマイナスのトリボ電荷が与えられる。さらに弾性ブレード６を円筒表面に接近して（間隔５０μｍ〜５００μｍ）、多極永久磁石の一つに磁石位置に対向して配置することにより、磁性トナー層の厚さを薄く（３０μｍ〜３００μｍ）かつ均一に規制して、現像部における感光ドラム１と現像スリーブ５の間隙よりも薄い磁性トナー層を形成する。現像スリーブ５の回転速度を調整することにより、スリーブ表面速度が感光ドラム表面の速度と実質的に等速、もしくはそれに近い速度となるようにする。弾性ブレード６として鉄製ブレードを使用しても良い。
【０１１２】
現像部において現像スリーブ５に交流バイアスまたはパルスバイアスをバイアス手段８により印加しても良い。この交流バイアスはｆが２００〜４，０００Ｈｚ、Ｖｐｐが５００〜３，０００Ｖであれば良い。
【０１１３】
現像部における磁性トナーの移転に際し、感光ドラム表面の静電的及び交流バイアスまたはパルスバイアスの作用によって磁性トナーは静電像側に移転する。
【０１１４】
弾性ブレード６は、シリコーンゴムの如き弾性材料で形成されており、弾性ブレード６を用いて押圧によって磁性トナー層の層厚を規制し、現像スリーブ５上に磁性トナー１３を塗布している。
【０１１５】
図５は、本発明に好適に用いられる接触帯電手段の一形態である帯電ローラについての構成図である。
【０１１６】
４２は帯電ローラであり、中心の芯金４２ａとその外周を形成した導電性弾性層４２ｂと表面層４２ｃとを基本構成とするものである。帯電ローラ４２は、感光ドラム１の表面に押圧力をもって圧接され、感光ドラム１の回転に伴い従動回転する。感光ドラム１はアルミニウムの如き導電性金属で形成されている導電性基層１ａと、その外面に形成した光導電層１ｂとを基本構成層とするものであり、図面上時計方向に所定の周速度（プロセススピード）で回転される。帯電ローラ４２は、バイアス印加手段Ｅにより電圧が印加され、帯電ローラ４２にバイアスが印加されることで感光ドラムの表面が所定の極性・電位に帯電される。次いで、画像露光により静電荷像が形成され、現像手段により静電荷像はトナー画像として順次可視化されていく。
【０１１７】
帯電ローラを用いた時の好ましいプロセス条件としては、ローラの当接圧が５〜５００ｇ／ｃｍで直流電圧に交流電圧を重畳したものを用いた時には、交流電圧＝０．５〜５ｋＶｐｐ、交流周波数＝５０Ｈｚ〜５ｋＨｚ、直流電圧＝±０．２〜±５ｋＶであり、直流電圧のみを用いた時には、直流電圧＝±０．２〜±５ｋＶである。
【０１１８】
帯電ローラの材質としては、導電性ゴム、例えばエチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）が好ましく、その表面に離型性被膜を設けてもよい。離型性被膜としてはナイロン系樹脂、ポリフッ化ビニリデン（ＰＶＤＦ），ポリ塩化ビニリデン（ＰＶＤＣ）が好ましく用いられる。
【０１１９】
次に本発明のプロセスカートリッジについて図６を用いて説明する。
【０１２０】
本発明のプロセスカートリッジは、少なくとも現像手段と潜像保持体とが一般的にカートリッジ化されたものであり、画像形成装置本体（例えば、複写機、レーザービームプリンター、ファクシミリ装置）に着脱可能に構成されている。
【０１２１】
図６に示した実施形態では、現像手段７０９、ドラム状の静電荷像保持体（感光ドラム）１、クリーニングブレード７０８ａを有するクリーニング手段７０８、一次帯電手段としての接触帯電手段７４２を一体としたプロセスカートリッジ７５０が例示される。
【０１２２】
本実施形態では、現像手段７０９は、トナー層厚規制手段としての弾性規制ブレード７１１とトナー容器７６０内に磁性トナー７１０を有し、該磁性トナー７１０を用い、現像時にはバイアス印加手段からの現像バイアス電圧により感光ドラム１とトナー担持体としての現像スリーブ７０４との間に所定の電界が形成されて現像工程が実施される。この現像工程を好適に実施するためには、感光ドラム１と現像スリーブ７０４との間の距離が調整される。
【０１２３】
上記では、現像手段７０９、潜像保持体１、クリーニング手段７０８及び一次帯電手段７４２の４つの構成要素を一体的にカートリッジ化した実施形態について説明したが、本発明においては、現像手段と静電荷像保持体との少なくとも２つの構成要素が一体的にカートリッジ化されたものであればよく、現像手段、静電荷像保持体及びクリーニング手段の３つの構成要素、現像手段、静電荷像保持体及び一次帯電手段の３つの構成要素、或いは、その他の構成要素を加えて一体的にカートリッジ化することも可能である。
【０１２４】
【実施例】
本発明を以下の実施例に基づいてより具体的に説明する。
【０１２５】
実施例１
（ｉ）結着樹脂 １００重量部
（ａ）スチレン−アクリル酸ｎ−ブチル共重合体（共重合重量比＝８０：２０）
（ｂ）ＧＰＣにおいて、分子量１．５万にメインピークを有し、分子量６５万にサブピークを有する。
（ｃ）重量平均分子量（Ｍｗ） ２５万
【０１２６】
（ｉｉ）磁性微粉体 １００重量部
（ａ）個数平均粒径Ｒ：０．１８μｍ
（ｂ）磁性微粒子の形状：球形
（ｃ）σ_r ：５．９〔Ａｍ² ／ｋｇ〕
（ｄ）Ｈ_C ：６．４〔ｋＡ／ｍ〕
（ｅ）σ_r ×Ｈ_C ：３８〔ｋＡ² ｍ／ｋｇ〕
（ｆ）磁性微粒子の裏面に存在する二酸化ケイ素のＷ：０．１３重量％
（ｇ）Ｗ×Ｒ：０．０２４
【０１２７】
（ｉｉｉ）負荷電制御剤 ２重量部
（ａ）前記式（ａ）で示されるモノアゾ錯体
【０１２８】
【外７】

【０１２９】
（ｉｖ）ワックス ５重量部
（ａ）長鎖アルキルアルコール
（ｂ）炭素数の平均値：５０個
（ｃ）軟化点：９８℃
（ｅ）軟化点の測定方法：ＤＳＣ吸熱ピーク温度
【０１３０】
上記材料をヘンシェルミキサーで混合して混合物を得、得られた混合物を二軸エクストルーダー（機種名「ＴＥＭ−１００Ｂ」東芝機械株式会社製）に導入し、表１に示す混練条件Ｂで混合物の溶融混練をおこなった。混練直後の混練物の温度は、１５９℃であった。混練物をハンマーミルで１ｍｍ以下に粗粉砕し、得られた粗粉砕物をジェット気流を用いた衝突式気流粉砕機で微粉砕し微粉砕物を得た。
【０１３１】
図１２に示す分級システムにおいて、得られた微粉砕物を供給機２０２を介して振動フィーダー２０３及び原料供給管１１６を介して３６０ｋｇ／ｈの割合でコアンダ効果を利用して粗粉体群Ｇ、中粉体群Ｍ及び微粉体群Ｆの３種に分級するために図７に示す多分割分級機２０１に導入した。
【０１３２】
導入に際しては排出口１１１、１１２、１１３に連通している捕集サイクロン２０４、２０５、２０６の吸引減圧による系内の減圧から派生する吸引力と原料供給管１１６に取付けたインクジェクションノズル１３１からの空気圧縮（圧力１．５ｋｇ／ｃｍ² ）を利用した。
【０１３３】
分級域の形状を変更するために、図１１に示す各々の設定距離を下記の如く設定し、分級をおこなった。
Ｌ₀ ＝６ｍｍ（原料供給ノズル排出口１１６ａの高さ径）
Ｌ₁ ＝３２ｍｍ（分級エッジ１１７の側面とコアンダブロック１２６の側面との距離）
Ｌ₂ ＝３３ｍｍ（分級エッジ１１７の側面と分級エッジ１１８の側面との距離）
Ｌ₃ ＝３９ｍｍ（分級エッジ１１８の側面と側壁１２３の側面との距離）
Ｌ₄ ＝１８ｍｍ（分級エッジ１１７の先端とコアンダブロック１２６の側面との距離）
Ｌ₅ ＝３３ｍｍ（分級エッジ１１８の先端とコアンダブロック１２６の側面との距離）
Ｌ₆ ＝２５ｍｍ（入気エッジ１１９の先端とコアンダブロック１２６の側面との距離）
Ｒ＝１４ｍｍ（コアンダブロック１２６の狐の半径）
【０１３４】
導入された微粉砕物は０．１秒以下の瞬時に分級された。
【０１３５】
磁性トナー粒子として使用する中粉体群Ｍは重量平均粒径（Ｄ₄ ）が５．７μｍであり、吸光度は０．５５であり、形状係数ＳＦ−１が１５４であり、形状係数ＳＦ−２が１４３であり、ＳＦ−１／ＳＦ−２の値は、１．０８であった。得られた磁性トナー粒子の物性を表２に示す。さらに、表３に、磁性微粉体の分散状態及びワックスの分散状態を示す。
【０１３６】
得られた磁性トナー粒子１００重量部と、シランカップリング剤とジメチルシリコーンオイルとで表面処理している疎水性シリカ微粉体（ＢＥＴ比表面積１１０ｍ² ／ｇ）１．５重量部とを混合して、負摩擦帯電性の磁性トナーを調製した。
【０１３７】
図４に示す画像形成方法で磁性トナーの評価をおこなうために、６００ｄｐｉの解像性を有する反転現像方法で静電荷像を現像するレーザビームプリンタ（商品名ＬＢＰ−４５０、キヤノン株式会社製）用のプロセスカートリッジの現像器に磁性トナーを導入し、プロセスカートリッジをレーザビームプリンタに装着し、各環境下において画出し試験をおこなった。
【０１３８】
さらに、１２００ｄｐｉの解像度を有するように改造したレーザビームプリンタを使用してドット潜像の画質を評価した。
【０１３９】
評価結果を、表４、表５、及び表６に示す。
【０１４０】
評価方法
（ａ）画像濃度
初期（２枚目）、３０００枚目及び６０００枚目のベタ黒画像の画像濃度をマクベス濃度計により測定した。
【０１４１】
（ｂ）カブリ
“リフレクタメーター”（東京電色（株））を用い、あらかじめプリント前の転写紙の白色度を測定し、プリントされた白色画像部の白色度との差を求め、その差が最大となる値を示した。
【０１４２】
（ｃ）帯電ローラ汚れ
６０００枚耐久後に帯電不良画像の発生し易いハーフトーン画像により評価を行なった。
ランク５：接触帯電ローラの汚れに基因した不良画像の発生なし。
ランク３：接触帯電ローラの汚れに基因した不良画像発生が確認されるが、実用上問題とならないレベル。
ランク１：接触帯電ローラの汚れに基因した不良画像の発生が確認され、不良画像が実用上問題となるレベル。
ランク４はランク５と３の中間レベルであり、ランク２はランク３と１の中間レベルである。
【０１４３】
（ｄ）６００ｄｐｉのドット画像
１インチ当り６００個のドット潜像を形成し得る画出し条件で、ワンドットのトナー画像を形成し、トナー画像を拡大して目視により４段階に評価した。
Ａ：優
Ｂ：良
Ｃ：普通
Ｄ：悪い（トナーの飛び散りの発生がみられたり、ドットの画像の形状がいびつである）
【０１４４】
（ｅ）１２００ｄｐｉのドット画像
１インチ当り１２００個のドット潜像を形成し得る画出し条件で、ワンドットのトナー画像を形成し、トナー画像を拡大して目視により４段階に評価した。
Ａ：優
Ｂ：良
Ｃ：普通
Ｄ：悪い（トナーの飛び散りの発生がみられたり、ドットの画像の形状がいびつである）
【０１４５】
（ｆ）ドラム融着
６０００枚耐久を行なった後のベタ黒画像上に生ずるＯＰＣ感光ドラム付着した付着物に基因する白点の発生程度により評価した。
ランク５：全く発生しなかった。
ランク３：数点発生が見られるが、実用上問題なし。
ランク１：発生が多く（数十点）、実用上問題あり。
ランク４はランク５と３の中間レベルであり、ランク２はランク３と１の中間レベルである。
【０１４６】
（ｇ）朝の一枚目の画像濃度
高温高湿環境下で、１５００枚／日の耐久で３日目の朝の一枚目（３００１枚に相当）のベタ黒画像濃度を測定。
【０１５７】
実施例１１，１３及び１４、参考例１及び２
使用する磁性微粉体、混練条件及び分級条件等を変更して表２に示す磁性トナー粒子を得た。得られた磁性トナー粒子と疎水性シリカ微粉体とを混合して磁性トナーを調製し、実施例１と同様にして画出し評価をおこなった。評価結果を表４、表５、表６に示す。
【０１５８】
比較例１
混練条件を表１に示すＧにする以外は、実施例２と同様にして磁性トナーを作製し評価を行なった。磁性トナー粒子の濡れ性試験における吸光度は０．７２であり、ＳＦ−１＝１５５，ＳＦ−２＝１４４であり、混練物の温度は１５２℃であった。結果を表２に示す。
【０１５９】
比較例２
混練条件を表１に示すＨにする以外は、実施例２と同様にして磁性トナーを作製し評価を行なった。磁性トナー粒子の吸光度は０．７７であり、ＳＦ−１＝１５５，ＳＦ−２＝１４３であり、混練物の温度は１５３℃であった。磁性トナー粒子の物性を表２に示し、評価結果を表４、表５、表６に示す。
【０１６０】
比較例３
混練条件を表１に示すＩにする以外は、実施例２と同様にして磁性トナーを作製し評価を行なった。磁性トナー粒子の吸光度は０．１８であり、ＳＦ−１＝１５５，ＳＦ−２＝１４３であり、混練物の温度は１６０℃であった。磁性トナー粒子の物性を表２に示し、評価結果を表４、表５、表６に示す。
【０１６１】
比較例４乃至６
使用する磁性微粉体、混練条件及び分級条件等を変更して表２に示す磁性トナー粒子を得た。得られた磁性トナー粒子と疎水性シリカ微粉体とを混合して磁性トナーを調製し、実施例１と同様にして画出し評価をおこなった。評価結果を表４、表５、表６に示す。
【０１６２】
【表１】

【０１６３】
【表２】

【０１６４】
【表３】

【０１６５】
【表４】

【０１６６】
【表５】

【０１６７】
【表６】

【０１８２】
【発明の効果】
本発明の磁性トナーは、特定の濡れ性を有する磁性トナー粒子を使用することによって、低温・低湿環境においても濃度が高く、カブリが少なく、帯電ローラ汚れの発生がなく、且つ高温・高湿環境においても濃度が高く、ドラム融着の発生のない画像を提供することが可能となった。
【図面の簡単な説明】
【図１】混練機の温度制御ユニット構成及び軸構成の概略的説明図である。
【図２】シリンダ断面構成の概略的説明図である。
【図３】樹脂温度と遊離磁性微粒子の量及びワックスの分散性との相関図である。
【図４】本発明の磁性トナーを用いる電子写真装置の一例の概略的説明図である。
【図５】本発明に好適に用いられる接触帯電手段の概略的説明図である。
【図６】本発明のプロセスカートリッジの一例を示す概略的説明図である。
【図７】磁性トナー粒子多分割分級するためのコアンダ効果を利用した気流式分級装置の概略的断面図である。
【図８】図７に示す気流式分級装置の斜視図である。
【図９】図７に示す気流式分級装置の斜視図である。
【図１０】図７におけるＡ−Ａ′断面図である。
【図１１】図７の要部を示す図である。
【図１２】磁性トナー粒子の分級に用いた分級プロセスの一例を示す説明図である。
【符号の説明】
１ 静電荷像担持体
２ 一次帯電装置
３ 露光光学系
４ 現像装置
５ トナー担持体
６ トナー層厚規制部材
７ トナー攪拌手段
８ 現像バイアス電源
９ 転写装置
１０ 転写電流発生装置
１１ クリーニング手段
１２ 定着装置
１３ 磁性トナー
７０４ 現像スリーブ
７０９ 現像器
７１０ 現像剤（磁性トナー）
７４２ 接触帯電手段
７４３ バイアス印加手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic toner for developing an electrostatic image in an image forming method such as electrophotography to form a toner image, a method for producing the same, an image forming method using the magnetic toner, and a process having the magnetic toner It relates to the cartridge.
[0002]
[Prior art]
In recent years, functions of an image forming apparatus using an electrophotographic technique such as a copying machine and a laser beam printer have been diversified, and further higher definition and higher image quality have been demanded.
[0003]
As a result, magnetic toner particles tend to use finer particle diameters than before. However, when the particle size of the magnetic toner particles is reduced, high definition of the image is achieved, but fogging due to adhesion of the magnetic toner to the non-image area is likely to occur, particularly in a low temperature / low humidity environment. Further, in a high temperature / high humidity environment, the image density tends to be low in copying or printing at the beginning of the morning. Furthermore, today, a method of charging a photosensitive member with a contact charging member without using a corona charger that generates ozone has been adopted due to consideration of environmental problems.
[0004]
However, in this case, in a low temperature / low humidity environment, fine particles of magnetic toner that are not cleaned well by the cleaning member adhere to the contact charging member (hereinafter referred to as “charging roller dirt”), and thus charging occurs. A defective image may occur. Further, in a high temperature and high humidity environment, a phenomenon (hereinafter referred to as “drum fusion”) occurs in which the above-described fine particles are pressure-bonded by the charging member and adhere to the surface of the photosensitive drum as the electrostatic charge image holding member. It becomes easy.
[0005]
It has been confirmed that the fine particles are mainly silica fine powder used as a fluidity improver and / or magnetic fine powder which is a constituent material of magnetic toner particles. Further, as described above, in the case of a magnetic toner having a smaller diameter than the conventional one, the magnetic fine powder tends to adhere more to the contact charging member and the photosensitive drum.
[0006]
In order to improve the adhesion between the binder resin and the magnetic fine powder, a method of previously treating the surface of the magnetic fine powder with an organic substance has been known. A toner layer coating defect (blot phenomenon) is likely to occur. Further, the surface treatment of the magnetic fine powder increases the production cost.
[0007]
As means for solving the above problems, a proposal of a new toner and a proposal of a new manufacturing method in which the presence state of the magnetic fine powder existing on the surface of the magnetic toner particle is controlled is awaited.
[0008]
It is difficult for the binder resin to uniformly disperse all raw materials such as magnetic fine powder and wax in the kneaded product. For example, the kneading conditions in consideration of the wettability between the binder resin and the magnetic fine powder and the kneading conditions in consideration of the dispersibility of the binder resin and the wax are generally in a contradictory relationship.
[0009]
Japanese Patent Application Laid-Open No. 8-128303 proposes a toner manufacturing method that defines temperature conditions for melt kneading using a screw extruder having a feed screw portion and a kneading portion. In the examples of this publication, the volume average particle size (d₅₀) Of 7.15 to 7.23 μm is described, but even with this manufacturing method, if the average particle size of the magnetic toner becomes smaller (for example, 5 μm), the magnetic toner The magnetic fine particles are easily released from the particle surface, and the tendency for the number of free magnetic fine particles to increase increases. Furthermore, in this manufacturing method, the temperature on the outlet side of the kneaded product of the extruder is set low, but this is a condition for forcibly cooling the kneaded product that has generated heat in the extruder, and it is generally difficult to control the temperature. In many cases, the load is large and process management in actual production is difficult.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide a magnetic toner that is less likely to cause fogging in a low-temperature and low-humidity environment and is less likely to cause charging failure, and a method for manufacturing the same.
[0011]
A further object of the present invention is to provide a magnetic toner capable of forming an image with a high image density in a high temperature and high humidity environment and suppressing the occurrence of drum fusion on the surface of the photosensitive drum, and a method for producing the same. .
[0012]
Furthermore, an object of the present invention is to provide a magnetic toner having a small weight average particle diameter and less magnetic fine particles are released from the magnetic toner particles, and a method for producing the same.
[0013]
Furthermore, an object of the present invention is to provide an image forming method using the magnetic toner.
[0014]
A further object of the present invention is to provide a process cartridge having the magnetic toner.
[0015]
[Means for Solving the Problems]
  The present invention relates to a binder resin, a magnetic fine powder, andLong chain alkyl alcoholA magnetic toner for developing an electrostatic image having magnetic toner particles containing at least a wax,
  The magnetic toner particles are prepared by mixing a mixture containing at least a binder resin, magnetic fine powder and a long-chain alkyl alcohol wax with a kneading machine using the following kneading conditions.
2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ⁴
E = kω ² T, ε = F / (πD ² L)
(Wherein, ω represents the screw rotation speed (m / min), T represents the set temperature (K), F represents the supply amount of the mixture (kg / min), and D represents the cylinder inner diameter (m). , L represents the effective screw length (m), π represents the circumference, and k represents (D ₀ / D) ² D ₀ Is 0.1 m. )
It is manufactured by melt-kneading so as to satisfy
  The magnetic fine powder is contained in the magnetic toner particles in an amount of 40 to 60% by weight,
  The magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm; the wavelength of a dispersion liquid in which 15 mg of the magnetic toner particles are dispersed in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73). Absorbance at 600nm0.35Thru0.69The present invention relates to a magnetic toner for developing an electrostatic charge image.
[0016]
  Furthermore, the present invention provides a binder resin, a magnetic fine powder andLong chain alkyl alcoholA method for producing a magnetic toner having magnetic toner particles containing at least a wax,
  Binder resin, magnetic fine powder andLong chain alkyl alcoholThe mixture having at least a wax is subjected to the following conditions by a kneader.
2.2 × 10³≦ E / ε ≦ 2.0 × 10⁴
E = kω²T
ε = F / (πD²L)
[In the formula, ω represents the screw rotation speed (m / min), T represents the set temperature (K), F represents the supply amount of the mixture (kg / min), and D represents the cylinder inner diameter (m). , L represents the effective screw length (m), π represents the circumference, and k represents (D₀/ D)²D₀Is 0.1 m. ]
The mixture is melt-kneaded, the kneaded product is cooled, the cooled product is pulverized, and the pulverized product is classified to obtain magnetic toner particles.Has a process,
  The magnetic toner particles contain 40 to 60% by weight of the magnetic fine powder;
  The magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm; the wavelength of a dispersion liquid in which 15 mg of the magnetic toner particles are dispersed in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73). Absorbance at 600nm0.35Thru0.69The present invention relates to a method for producing a magnetic toner.
[0017]
  Further, according to the present invention, an electrostatic charge image holding member is charged by a contact charging means to which a bias is applied, an electrostatic charge image is formed on the charged electrostatic charge image holding member by exposure, and a developing means having magnetic toner is used. An image forming method for developing the electrostatic charge image to form a magnetic toner image;
  TheMagnetic tonerBut,Magnetic tonerThe present invention relates to an image forming method.
[0018]
  Furthermore, the present invention is a process cartridge that has an electrostatic charge image holding member, a contact charging means for charging the electrostatic charge image holding member, and a developing means that holds magnetic toner, and is detachable from the main body of the image forming apparatus. ,
  TheMagnetic tonerBut,Magnetic tonerThe present invention relates to a process cartridge.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Similar problems to magnetic toner particles constituting magnetic toner that easily causes drum fusing of toner on the surface of a photosensitive drum that is one of contact roller charging means and one of electrostatic charge image holders. We examined a means to easily know the difference from magnetic toner particles that are difficult to generate by a method other than image output evaluation. A method using a dispersion of magnetic toner particles in a mixture of ethyl alcohol and water was used. I found out that it was possible to know the difference. A high absorbance of the dispersion indicates that the magnetic toner particles are very easily wetted with the liquid mixture, and that a large amount of magnetic fine powder is present on the surface of the magnetic toner particles. Such magnetic toner particles easily release magnetic fine particles from the surface. In fact, when the magnetic toner produced from such magnetic toner particles is imaged and evaluated, the problem of contamination on the charging roller and fusing on the surface of the photosensitive drum tends to occur. It was confirmed that many magnetic fine particles were present in the contamination on the surface of the charging roller and the fused material on the surface of the photosensitive drum. It can be said that this is a measurement method that clearly and appropriately shows the amount of the magnetic fine powder present on the surface of the magnetic toner particles.
[0020]
The magnetic toner particles used in the present invention have a weight average particle diameter of 3.5 to 6.5 μm, and the magnetic toner particles are added to 19 ml of a mixture of ethyl alcohol and water (ethyl alcohol: water volume ratio 27:73). The absorbance at a wavelength of 600 nm of the dispersion liquid in which 15 mg of toner particles are dispersed is 0.2 to 0.7.
[0021]
The weight average particle diameter of the magnetic toner particles or magnetic toner is measured by a Coulter counter method.
[0022]
For example, a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co., Ltd.) is used as an apparatus for measuring the magnetic toner particles and the average particle diameter of the magnetic toner by the Coulter counter method. As the electrolyte, first grade sodium chloride is used to prepare an approximately 1% NaCl aqueous solution. For example, ISOTON-II (manufactured by Coulter) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the volume and number of magnetic toner particles or magnetic toner are measured with the measuring apparatus using an aperture of 100 μm. The volume distribution and the number distribution are calculated. Then, the weight-based weight average particle diameter (D4) of the magnetic toner particles or magnetic toner is obtained.
[0023]
As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.
[0024]
In the above measurement method, even if an external additive is externally added to the magnetic toner particles, the weight average particle diameter of the magnetic toner usually shows substantially the same value as the weight average particle diameter of the magnetic toner particles.
[0025]
The absorbance of the magnetic toner particles is measured by the following method.
[0026]
i) Preparation of dispersion
An aqueous solution having a mixing ratio of ethyl alcohol (special grade 99.5%, manufactured by Kishida Chemical) and water of 27:73 is prepared. 19 ml of this aqueous solution is put into a 20 ml sample bottle (manufactured by Iuchi, name Laboran Pack), and 15 mg of magnetic toner particles are infiltrated on the liquid surface to cover the bottle. Let it stand in that state for 20 minutes. Over time, particles that are easily wet start to fall and disperse in the solution. After 20 minutes, the sample bottle is grasped with a finger, and the top and bottom of the sample bottle are shaken by rotating 5 times and 180 ° to homogenize the dispersion to obtain a measurement dispersion.
[0027]
ii) Absorbance measurement
The dispersion obtained in i) is placed in a 1 cm square quartz cell, and the absorbance at a wavelength of 600 nm of the dispersion is measured using a spectrophotometer MPS2000 (manufactured by Shimadzu Corporation).
[0028]
When the absorbance is greater than 0.7, a large amount of magnetic fine particles are present on the surface of the magnetic toner particles, and free magnetic fine particles are likely to be generated, so that charging roller contamination and drum fusion are likely to occur. On the other hand, when the absorbance is less than 0.2, the exposure of the magnetic fine particles to the surface of the magnetic toner particles is excessively suppressed, so that the image density is reduced by charging up the magnetic toner particles in a low temperature / low humidity environment. Problems are likely to occur. The absorbance is preferably 0.30 to 0.69, more preferably 0.35 to 0.65.
[0029]
Weight average particle diameter of magnetic toner particles (D_Four ) Is 3.5 to 6.5 μm, and it is difficult to achieve high image quality when the particle size is larger than 6.5 μm, and when the particle size is smaller than 3.5 μm, the fog is increased, the density is low, and the productivity is lowered. Is likely to occur.
[0030]
The content of the magnetic powder in the magnetic toner particles is preferably 40 to 60% by weight. In the case of a magnetic toner in which the magnetic toner particles have a smaller weight average diameter than the conventional one, if the amount of magnetic fine powder in the magnetic toner particles is less than 40% by weight, it is difficult to suppress the increase in fog, and the amount is more than 60% by weight. When the amount is large, image density is lowered or free magnetic fine particles are likely to be generated, and charging roller contamination and drum fusion are liable to occur due to the increase of free magnetic fine particles.
[0031]
The magnetic toner particles preferably have a shape factor SF-1 value of 140 <SF-1 ≦ 180 and a shape factor SF-2 value of 130 <SF-2 ≦ 170 as measured by an image analyzer.
[0032]
When the magnetic toner particle shape factor SF-1 or SF-2 is 130 or less, the surface of the magnetic toner particle is smooth. When the magnetic toner particle diameter is made finer than before, a charge-up phenomenon occurs. It becomes easy to cause a thin image density or a blotch phenomenon in a low temperature / low humidity environment. When the shape factor SF-1 of the magnetic toner particles is larger than 180, the fluidity of the magnetic toner is likely to be lowered and the image density is likely to be lowered. When the shape factor SF-2 of the magnetic toner particles is larger than 170, it is difficult to obtain uniform charging and fogging is likely to occur.
[0033]
In the present invention, the shape factors SF-1 and SF-2 are, for example, 100 toner particle images having a particle diameter of 2 μm or more obtained by magnifying magnetic toner particles 1000 times using FE-SEM (S-800) manufactured by Hitachi, Ltd. Samples are randomly sampled, and the image information is introduced into, for example, an image analysis apparatus (Luzex III) manufactured by Nicole via an interface and analyzed, and the value obtained from the following equation is calculated as a shape factor SF-1, It is defined as SF-2.
[0034]
[Outside 1]

(In the formula, MXLNG represents the absolute maximum length of the particle, PERIME represents the periphery of the particle, and AREA represents the projected area of the particle.)
[0035]
The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles.
[0036]
The magnetic toner particles preferably have a shape factor SF-1 to SF-2 ratio (SF-1 / SF-2) of 1.01-1.20. More preferably, the magnetic toner particles may have a shape factor SF-1 of 145 to 160, SF-2 of 135 to 155, and a ratio of the shape factors SF-1 and SF-2 (SF -1 / SF-2) is preferably 1.05-1.15.
[0037]
Even when SF-1 and SF-2 of the magnetic toner in which the external additive is externally added to the magnetic toner particles are measured, the external additive has a very small particle size or a large particle size. In general, substantially the same value as that of the magnetic toner particles SF-1 and SF-2 is shown.
[0038]
In the magnetic toner of the present invention, the residual magnetization [σ of the magnetic fine powder under a magnetic field of 795.8 kA / m (10 k Oersted) [σ_r (Am² / Kg)] and coercive force [H_C (KA / m)] product (σ_r × H_C ) Is 24-56 (kA)² m / kg).
[0039]
As a developing method in which the magnetic toner of the present invention is preferably used, a magnet is installed in the toner carrying body, the magnetic toner is held by the magnet, and frictional charging is performed on the toner carrying body, and the electrostatic toner is held by the charged magnetic toner. And a method of developing the electrostatic charge image. In such a developing method, when the magnetic toner particles having a weight average particle diameter of 3.5 to 6.5 μm constituting the magnetic toner of the present invention are used, the solid black density during fogging and durability in a low temperature / low humidity environment. The drum fusion phenomenon tends to occur in a thin phenomenon and in a high temperature / high humidity environment. These problems are related to the magnetic force (σ_r × H_C ) Can be effectively solved. In low-temperature and low-humidity environments, magnetic force is applied to the magnetic toner so that development of magnetic toner with increased triboelectric charge can be suppressed, thereby maintaining image density and better preventing fogging. can do.
[0040]
Furthermore, the magnetic toner is restrained on the surface of the toner carrier with a moderate magnetic restraint force, thereby improving the circulation of the magnetic toner on the surface of the toner carrier and causing excessive charge-up of the magnetic toner in a low temperature / low humidity environment. It is possible to prevent a solid black density thinning phenomenon at the time of durability. Further, magnetic toner particles having a high triboelectric charge amount are easily selectively developed even in a high temperature and high humidity environment. As the diameter of the magnetic toner particles decreases, the drum fusion phenomenon is more likely to occur. Even in this case, the magnetic toner can be prevented by applying a magnetic force capable of suppressing the development of the magnetic toner particles having a relatively high frictional charge amount.
[0041]
σ_r × H_C When a magnetic fine powder having a particle size of less than 24 is used, the magnetic binding force does not act effectively, so it is easy to fog in a low-temperature / low-humidity environment, and a solid black density thin phenomenon is likely to occur during durability. In the environment, the drum fusion phenomenon tends to occur. Also, σ_r × H_C On the other hand, when the value exceeds 56, the magnetic binding force is dominant, and the image density is liable to be lowered in the entire environment. A more preferable range is 30 to 52. In the present invention, the magnetic properties were measured with an external magnetic field of 795.8 kA / m using VSMP-1-10 (manufactured by Toei Industry Co., Ltd.).
[0042]
Examples of magnetic fine powders used in the magnetic toner of the present invention include magnetic metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. These magnetic fine powders preferably have a number average particle diameter of 0.05 to 0.30 μm, more preferably 0.10 to 0.25 μm. When the number average particle size is smaller than 0.05 μm, the color of the magnetic fine powder tends to be reddish, and in the case of a magnetic toner, the color is reflected in the color of the image. On the other hand, when the number average particle diameter is larger than 0.30 μm, the image density and the fogging latitude become narrow, which is not preferable.
[0043]
In addition, examples of the shape of the magnetic fine particles constituting the magnetic fine powder used in the present invention include octahedron, hexahedron, and spherical shape. The shape of the magnetic fine particles is preferably spherical because it can take a wide range of image density and fog latitude.
[0044]
Furthermore, in order to satisfy the problems of the present invention at a higher level, the magnetic fine particles constituting the magnetic fine powder have at least silicon dioxide on the surface, and the weight percent of silicon dioxide present on the surface is expressed as W (% ) When the number average particle diameter of the magnetic fine powder is R (μm), it is preferable that W × R satisfies 0.003 to 0.042. Hereinafter, W × R will be described.
[0045]
(A) Method for measuring W:
(1) Silicon dioxide (SiO2) present on the surface of magnetic fine particles constituting magnetic fine powder with 2N-NaOH solution₂ ) Is eluted (40 ° C., 30 minutes).
(2) SiO in magnetic fine powder before and after elution₂ The amount is measured by X-ray fluorescence analysis.
W (%) = [(SiO before elution₂ Quantity-SiO after elution₂ Amount) / (weight of magnetic fine powder before elution)] × 100
[0046]
(B) R measurement method:
R is a transmission electron microscope. A photograph of magnetic fine particles composing the magnetic powder fine powder is taken, and after arbitrarily selecting 250 particles enlarged by 40,000 times, the Martin diameter (in a fixed direction) in the projected diameter is selected. The length of the line segment that bisects the projected area is measured, and the number average particle diameter is calculated based on the measured value.
[0047]
By defining the value of W × R, SiO on the surface of the magnetic fine particles₂ The distinction of whether the existence state is dense or coarse can be grasped more clearly.
[0048]
First, where S is the specific surface area determined from the average particle diameter of the magnetic fine powder, and ρ is the density of the magnetic fine powder, S = 4πR.² × [1 / (4/3) πR^Three .Rho.] = 3 / R.rho. SiO of the above surface₂ Is actually given by W / S = R · W · ρ / 3. Since the preferable range of W / S is 0.001ρ ≦ W / S ≦ 0.014ρ, 0.001ρ ≦ R · W · ρ / 3 ≦ 0.014ρ, and when the formula is simplified, 0.003 ≦ W × R ≦ 0.042.
[0049]
When W × R is less than 0.003, the surface SiO of the magnetic fine powder particles₂ Is very sparse, so that the effect of imparting fluidity to the magnetic toner is small, and image density is lowered and fog is likely to increase in a low temperature and low humidity environment. When W × R is larger than 0.042, the wettability between the binder resin and the magnetic fine powder decreases during kneading, and the magnetic fine powder is easily detached from the magnetic toner particles during toner production. Drum fusion due to the body is likely to occur. A more preferable range of W × R is 0.008 to 0.035.
[0050]
The content of the magnetic fine powder in the magnetic toner particles is preferably 40 to 60% by weight. When the amount is less than 40% by weight, it is difficult to suppress the occurrence of the fog phenomenon in the magnetic toner particles having a weight average particle diameter of 3.5 to 6.5 μm. Roller dirt and drum fusion are likely to occur. More preferably, the content of the magnetic fine powder in the magnetic toner particles is 45 to 55% by weight.
[0051]
The magnetic toner particles of the magnetic toner of the present invention contain a wax. Examples of the wax include paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, carnauba wax and derivatives thereof, long chain carboxylic acids and derivatives thereof, and long chain alcohols and derivatives thereof. Can be mentioned. Derivatives include oxides, block copolymers of vinyl monomers and waxes, and graft modified products of vinyl monomers and waxes.
[0052]
The wax preferably used in the present invention is represented by the general formula RY (wherein R represents a hydrocarbon group, Y represents a hydroxyl group, a carboxyl group, an alkyl ether group, an ester group or a sulfonyl group). It is preferable that the weight average molecular weight (Mw) by gel permeation chromatography (GPC) of the wax shown by is 3000 or less.
[0053]
Specific examples of the compounds include the following.
(A) CH_Three (CH₂ )_n CH₂ OH (n = 20 to 300)
(B) CH_Three (CH₂ )_n CH₂ COOH (n = 20-300)
(C) CH_Three (CH₂ )_n CH₂ OCH₂ (CH₂ )_m CH_Three (N = 20-200, m = 0-100)
[0054]
The compounds (B) and (C) are derivatives of the compound (A), and the main chain is a linear saturated hydrocarbon. Any compound other than those shown in the above examples can be used as long as it is a compound derived from the compound (A). A particularly preferred wax is CH_Three (CH₂ )_n The main component is a long-chain alkyl alcohol represented by OH (n = 20 to 300) and a mixture thereof.
[0055]
When this long-chain alkyl alcohol wax is used, since the dispersibility between the binder resin and the wax during kneading is extremely good, the kneading conditions are set in consideration of the dispersibility of the wax excessively compared to the conventional kneading conditions. This eliminates the necessity, and allows setting of conditions in consideration of the wettability between the binder resin and the magnetic fine powder.
[0056]
  Generally, under conventional kneading conditions, the kneading temperature immediately after the kneaded material is discharged from the kneader is an important parameter for knowing the kneading state. Even under kneading conditions where the kneading temperature is 30 to 70 ° C. higher than the softening point of the long-chain alkyl alcohol wax, the dispersibility of the wax in the binder resin is good, and in such a case, the binder resin and The wettability with the magnetic fine powder is also improved, and the object of the present invention can be achieved better. Figure3reference.
[0057]
The binder resin used in the magnetic toner of the present invention will be described below.
[0058]
Examples of the binder resin for the toner used in the present invention include polystyrene; homopolymers of styrene substitution products such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, and styrene-vinyl. Toluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, Styrene vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, etc. Styrene copolymer; polyvinyl chloride , Phenolic resin, natural modified phenolic resin, natural modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene Resin, coumarone indene resin, petroleum resin and the like can be mentioned. Cross-linked styrene resins are also preferred binder resins.
[0059]
As a comonomer for the styrene monomer of the styrenic copolymer, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, Monocarboxylic acid having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; maleic acid, butyl maleate, methyl maleate, Dicarboxylic acid having a double bond such as dimethyl maleate and its substitutes: vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene Vinyl methyl ketone, vinyl ketones such as vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether. These vinyl monomers are used alone or in combination with the styrene monomer. As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These crosslinking agents are used alone or in combination.
[0060]
Furthermore, the styrene resin has a molecular weight of at least 0.5 × 10 in the molecular weight distribution measured by gel permeation chromatography (GPC).^Four ~ 5x10^Four And molecular weight 1.0 × 10^Five ~ 5.0 × 10⁶ It is preferably used when it has a main peak and a sub peak in the region. The styrene resin has a weight average molecular weight (Mw) of a soluble component of tetrahydrofuran (THF) of 1.5 × 10.^Five ~ 3.5 × 10^Five , More preferably 1.8 × 10^Five ~ 3.2 × 10^Five Is good.
[0061]
In the magnetic toner of the present invention, an organometallic compound is preferably used as a charge control agent. Among organic metal compounds, those containing an organic organic compound rich in vaporization and sublimation as a ligand or counter ion are particularly useful.
[0062]
As such an organometallic compound, there is an azo metal complex represented by the following general formula.
[0063]
[Outside 2]

[In the above general formula, M represents a coordination center metal, and examples thereof include Cr, Co, Ni, Mn, Fe, Al, Ti, Sc or V having a coordination number of 6. Ar is an aryl group and may have a substituent, such as a phenyl group or a naphthyl group. Examples of the substituent include a nitro group, a halogen group, a carboxyl group, an anilide group, and an alkyl group or alkoxy group having 1 to 18 carbon atoms. X, X ′, Y and Y ′ are —O—, —CO—, —NH— or —NR— (R represents an alkyl group having 1 to 4 carbon atoms).
[0064]
[Outside 3]

Represents hydrogen ion, sodium ion, potassium ion, ammonium ion, aliphatic ammonium ion or a mixed ion thereof. ]
[0065]
Specific examples of the complexes that are favorably used in the present invention are shown below.
[0066]
[Outside 4]

[0067]
[Outside 5]

[0068]
[Outside 6]

[0069]
The charge control agent is preferably added in the range of 0.2 to 5 parts by weight with respect to 100 parts by weight of the magnetic toner.
[0070]
In the magnetic toner, it is preferable to externally add inorganic fine powder to the magnetic toner particles in order to improve charging stability, developability, fluidity and durability.
[0071]
Examples of the inorganic fine powder include silica fine powder, titanium oxide fine powder, and alumina fine powder. In particular, the specific surface area is 30 m due to nitrogen adsorption measured by the BET method.² / G or more (especially 50 to 400 m² / G) inorganic fine powders in the range give good results. The inorganic fine powder is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the magnetic toner.
[0072]
In addition, the inorganic fine powder may be a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, a silane coupling agent having a functional group, for the purpose of hydrophobization and chargeability control, if necessary. It is also preferable that it is treated with a treating agent such as another organosilicon compound. Two or more kinds of treatment agents may be used. In particular, silica fine powder surface-treated with silicone oil is preferable.
[0073]
As other additives, for example, a lubricant such as Teflon, zinc stearate, polyvinylidene fluoride, silicone oil particles (containing about 40% silica) is preferably used. Abrasives such as cerium oxide, silicon carbide, calcium titanate, and strontium titanate are preferably used, and strontium titanate is particularly preferable. Further, a small amount of anti-caking agents; conductivity imparting agents such as carbon black, zinc oxide, antimony oxide, tin oxide; white fine particles and black fine particles having a polarity opposite to that of the magnetic toner particles may be used as a development improver.
[0074]
Next, a method for producing magnetic toner particles used for the magnetic toner will be described.
[0075]
The kneader used in the present invention is preferably kneaded using an extruder in response to the recent mass production of magnetic toners. In particular, a biaxial extruder is a preferable kneader from the viewpoint of quality stability and mass productivity. Specific examples include TEM-100B (manufactured by Toshiba Machine), PCM-87 (manufactured by Ikekai Tekko) and the like.
[0076]
In the present invention, in the melt-kneading step for producing magnetic toner particles, a mixture having at least a binder resin, magnetic fine powder, and wax is subjected to the following conditions by a kneader.
2.2 × 10^Three ≦ E / ε ≦ 2.0 × 10^Four
E = kω² T, ε = F / (πD² L)
[In the formula, ω represents the screw rotation speed (m / min), T represents the set temperature (K), F represents the supply amount of the mixture (kg / min), and D represents the cylinder inner diameter (m). , L represents the effective screw length (m), π represents the circumference, and k represents (D₀ / D)² D₀ Is 0.1 m. ]
It is preferable to melt-knead with.
[0077]
The kneading condition is defined by the value of E / ε because it is an effective value as an index for determining the wettability between the binder resin and the magnetic fine particles constituting the magnetic fine powder during kneading. It can be said that when E / ε is large, wettability is improved. E is the product of the square value of the rotational speed ω of the screw of the kneader and the kneading set temperature T, and can be regarded as a value representing the kneading energy of the kneader. ω² Is a value that correlates with the kinetic energy of the screw, and the set temperature T is a value that correlates with the thermal energy supplied by the kneader. If the raw material is kneaded with a kneader, the kneading state is considered as a physical quantity, it is considered that there is a close relationship with the sum of kinetic energy and thermal energy supplied from the kneader. Where ω² The reason for making the product with T is that the difference in the kneading state has been taken into account so that it can be grasped more clearly.
[0078]
k is a correction constant. This is because, from experience, the wettability tends to be improved by a kneader having a smaller cylinder inner diameter than a kneader having a cylinder inner diameter of 0.1 m.
[0079]
ε = F / (πD² L), where F is the amount of raw material supplied per unit time and πD² L is a value having a correlation with the possible volume of raw material in the cylinder of the kneader. ε represents the full state of the raw material in the cylinder. A large ε means that the full state is high. If the kneading energy is the same, if ε is large, the kneading energy per unit weight per unit time tends to decrease, and in fact, the wettability between the binder resin and the magnetic fine powder tends to decrease. .
[0080]
As described above, E / ε represents the kneading state for generating fine magnetic toner particles having a weight average particle diameter of 3.5 to 6.5 μm, the screw rotation speed and the set temperature that are the basis of the kneading conditions. , Focusing on the parameters of the discharge amount and the internal volume of the cylinder, it is defined from the two viewpoints of the kneading energy and the fullness of the raw material to which the energy is given in the kneader.
[0081]
E / ε is 2.2 × 10^Three If it is smaller, the wettability between the binder resin and the magnetic fine powder is reduced, and free magnetic fine powder is likely to be generated in the pulverization process. The resulting magnetic toner is liable to cause charging roller contamination and drum fusing. Become. E / ε is 2.0 × 10^Four If it is larger, the dispersibility between the binder resin and the wax tends to decrease, and fogging tends to occur in a low temperature / low temperature environment.
[0082]
The value range of each parameter defined in the kneading conditions is determined in consideration of the type of the kneader used.
[0083]
ω represents the screw rotation speed (m / min), and is used favorably in the range of 5-50. T represents a set temperature (K), and a range of 333 to 513 is preferably used. F shows the supply amount (kg / min) of a mixture, and the range of 0.15-25 is used favorably. D shows a cylinder internal diameter (m), and the range of 0.03-0.2 is used favorably. L represents an effective screw length (m), and a range of 1.00 to 4.00 is favorably used. π is the pi and k is (D₀ / D)² D₀ Is 0.1 [m]. Furthermore, E = kω² The value of T is preferably 3.0 × 10^Five To 16.0 × 10^Five The feed amount F of the mixture is preferably 0.30 to 12.0 (kg / min), and ε = F / (πD² The value of L) is preferably 85 to 130, and the value of E / ε is preferably 2.5 × 10^Three To 1.5 × 10^Four Is good.
[0084]
When setting the kneading conditions, various configurations of the kneading paddle configuration of the shaft screw can be considered, but preferably the kneading region is set in two regions, a region where melting starts and a region where dispersibility is improved. is there. The kneaded product is subjected to rolling cooling, coarse pulverization, fine pulverization with a jet stream, and classification by the multi-division method shown in FIG. 7 to obtain magnetic toner particles. Regarding the dispersibility of the magnetic fine powder and wax of the magnetic toner particles, the amount of magnetic fine powder and the amount of wax in the classified powder of M powder magnetic toner particles and F powder obtained in the multi-division classification process are compared. You can know.
[0085]
i) Dispersibility of magnetic fine powder
For example, by using a density meter Accupic 1330 (Shimadzu Corporation), know the dispersion state by the ratio F / M between the density value M of the magnetic toner particles of M powder and the density value F of the classification fine powder of F powder. Is possible. It can be determined that the uniform dispersibility of the magnetic fine particles constituting the magnetic fine powder in the binder resin decreases as the F / M value deviates from 1.
[0086]
ii) Wax dispersibility
In the DSC curve measured with a differential scanning calorimeter (manufactured by PerkinElmer), the area values M and F obtained from the DSC curve of the magnetic toner particles of M powder with respect to the area surrounded by the endothermic peak curve and the baseline, F It is possible to know the uniform dispersibility of the wax in the binder resin from the ratio F / M with the area value F obtained from the DSC curve of the fine powder classified powder. It can be determined that the dispersibility decreases as the value of F / M deviates from 1.
[0087]
As an example of an airflow classifier that can be used for the preparation of the magnetic toner particles of the present invention, an example of an apparatus of the type shown in FIG. 7 (cross-sectional view), FIG. 8 and FIG.
[0088]
In the airflow classifier and the air classification system using the apparatus, a high-pressure air introduction pipe and a powder are provided at the rear end of the raw material supply nozzle installed at an angle of preferably θ = 45 ° or less with respect to the vertical direction. A powder raw material serving as magnetic toner particles is supplied from a raw material supply port provided above the powder raw material introduction nozzle, and the supplied powder raw material is introduced with high-pressure air from the lower part of the powder raw material introduction port. Radiated from the outer periphery of the tube, accelerated by high-pressure air and dispersed well, and a well-dispersed powder raw material can be supplied to the raw material supply nozzle. And when changing the shape of the classification area, the classification area is expanded, the classification point can be changed significantly, and the classification point can be adjusted accurately without causing turbulence in the vicinity of the classification edge tip It is. The principle of the suction and discharge of the powder raw material in the powder raw material supply section is based on the expansion / reduction pressure ejector effect in the powder raw material supply nozzle of the high pressure air from the high pressure air introduction pipe.
[0089]
7, 8, and 9, the side walls 122 and 123 form a part of the classification chamber, and the classification edge blocks 124 and 125 include the classification edges 117 and 118. The classification edges 117 and 118 can be rotated about the axes 117a and 118a, and the classification edge tip position can be changed by rotating the classification edge. Each of the classification edge blocks 124 and 125 can be slid up and down, and the knife edge type classification edges 117 and 118 are also slid up and down. With the classification edges 117 and 118, the classification zone of the classification chamber 132 is divided into three.
[0090]
A powder having a raw material supply port 140 for introducing a powder raw material at the rearmost end portion of the raw material supply nozzle 116 and having a high-pressure air introduction pipe 141 and a powder raw material supply portion at the rear end portion of the raw material supply nozzle 116. A raw material supply nozzle 116 having a raw material introduction nozzle 142 and having an opening in the classification chamber 132 is provided on the right side of the side wall 122, and a Coanda block in which an elliptical arc is drawn with respect to the extending direction of the right side tangent of the raw material supply nozzle 116. 126 is installed. The left block 127 of the classification chamber 132 includes a knife-edge type inlet edge 114 on the left side of the classification chamber 132, and further, inlet tubes 114 and 115 that open to the classification chamber 132 are provided on the left side of the classification chamber 132. is there. The inlet pipes 114 and 115 are provided with a first gas introduction adjusting means 120 and a second gas introduction adjusting means 121 such as a damper, a static pressure gauge 128 and a static pressure gauge 129.
[0091]
The pressure of the high-pressure air introduced into the high-speed air introduction pipe 141 is 1.0 to 3.0 Kg / cm in normal classification.² However, in order to efficiently release and remove the magnetic fine particles adhering to the surface of the magnetic toner particles, the pressure of the high-pressure air is 3.0 kg / cm.² Higher, preferably 3.5 to 6.0 Kg / cm² Good to be. The positions of the classification edges 117 and 118 and the inlet edge 119 are adjusted according to the type of magnetic toner particles and the desired particle size.
[0092]
On the right side of the classification chamber 132, there are discharge ports 111, 112, and 113 that open to the classification chamber in correspondence with the respective classification areas. A communication means such as a pipe is connected to the discharge ports 111, 112, and 113. Opening / closing means such as valve means may be provided for each.
[0093]
The raw material supply nozzle 116 includes a right-angle cylinder part and a pyramid cylinder part, and the ratio of the inner diameter of the right-angle cylinder part and the inner diameter of the narrowest part of the pyramid cylinder part is 20: 1 to 1: 1, preferably 10: 1 to 2: If set to 1, good introduction speed is obtained.
[0094]
For example, the classification operation in the multi-division classification area configured as described above is performed as follows. The classification chamber is depressurized through at least one of the discharge ports 111, 112, and 113, and the raw material supply nozzle 116 having an opening in the classification chamber is pressurized with high-pressure air and an airflow flowing by the depressurization, preferably a flow rate of 50 to 300 m. The powder is ejected to the classification chamber through the raw material supply nozzle 116 at a speed of / sec.
[0095]
The magnetic toner particles in the powder raw material introduced into the classification chamber move by drawing curved lines 130a, 130b, 130c, etc. due to the action of the Coanda effect of the Coanda block 126 and the action of a gas such as air flowing in at that time. Depending on the size of each particle and the magnitude of the inertial force, large particles (coarse particles) are outside the air stream (ie the first fraction outside the classification edge 118) and intermediate particles are at the classification edges 118 and 117. In the second fraction, the small particles are classified into the third fraction inside the classification edge 117, and the G powder consisting of the classified large particles is discharged from the discharge port 111 and consists of the classified intermediate particles. The M powder is discharged from the discharge port 112, and the F powder composed of classified small particles is discharged from the discharge port 113.
[0096]
In the classification of the magnetic toner particles, the classification point is mainly determined by the edge tip positions of the classification edges 117 and 118 with respect to the lower end portion of the Coanda block 126 where the magnetic toner particles jump out into the classification chamber 132. Further, the classification point is affected by the flow rate of the classification air flow or the ejection speed of the magnetic toner particles from the raw material supply nozzle 16.
[0097]
In the airflow classifier, the powder raw material is supplied from the raw material supply port 140, and the supplied powder raw material is radiated from the outer periphery of the high pressure air introduction pipe 141 from the lower part of the powder raw material introduction port 142, and from the high pressure air introduction pipe 141. Powder that is accelerated by riding on the high-pressure air that is blown out and dispersed well, is instantaneously introduced into the classification chamber from the raw material supply nozzle 116, and then discharged out of the classifier system. It is important for the body material to fly with a propulsive force in a state where the aggregated powder is dispersed to the primary particles without disturbing the trajectory of the individual particles from the material supply nozzle 116 through the introduction port portion in the classification chamber. When the powder flow is introduced from above, the particle flow flowing from the inside of the raw material supply nozzle 116 is introduced into the classification chamber 132 having the Coanda block 126 on the side of the opening of the raw material supply nozzle 116. The particle trajectory is dispersed according to the size of the particle without disturbing the flight trajectory of the particle, so that the classification edge is moved in the direction along the streamline, and then the edge tip position of the classification edge is fixed. And can be set to a predetermined classification point. When the classification edges 117 and 118 are moved, the edge direction can be aligned with the flow direction of the particle flow flying along the Coanda block 126 by simultaneous movement with the classification edge blocks 124 and 125.
[0098]
Specifically, in FIG. 12, the distance between the tip of the classification edge 117 and the side surface of the Coanda block 126 around, for example, the position O in the Coanda block 126 corresponding to the side surface portion of the tip opening 116 a of the raw material supply nozzle 116. L_Four And the distance L between the side surface of the classification edge 117 and the side surface of the Coanda block 126.₁ Moves the classification edge block 124 up and down along the positioning member 133 to move the classification edge 117 up and down along the positioning member 134, and further rotates the tip of the classification edge 117 around the axis 117 a Can be adjusted.
[0099]
At the same time, the distance L between the tip of the classification edge 118 and the side wall of the Coanda block 126_Five The distance L between the side surface of the classification edge 117 and the side surface of the classification edge 118₂ Alternatively, the distance L between the side surface of the classification edge 118 and the side surface of the side wall 123._Three Moves the classification edge block 125 up and down along the positioning member 138 to move the classification edge 118 up and down along the positioning member 136, and further rotates the tip of the classification edge 118 about the shaft 118 a Can be adjusted.
[0100]
The Coanda block 126 and the classification edges 117 and 118 are installed on the side surface portion of the front end opening 116a of the raw material supply nozzle 116, and the classification chamber block and / or the classification edge block 125 is changed in accordance with the change of the installation position of the classification chamber. The classification area is expanded, and the classification point can be easily and significantly changed.
[0101]
Therefore, it is possible to prevent the disturbance of the flow due to the tip of the classification edge, and by adjusting the flow rate of the suction flow due to the decompression through the discharge conduits 111a, 112a and 113a, the particle flying speed is increased and the toner particles in the classification region In addition to improving the dispersion of the product, better classification accuracy can be obtained even at higher dust concentrations, preventing a decrease in product yield, and better classification accuracy and improvement in product yield can be achieved even at the same dust concentration. become.
[0102]
The distance L between the tip of the inlet edge 119 and the wall surface of the Coanda block 126₆ Can be adjusted by rotating the tip of the inlet edge 119 about the shaft 119a, thereby adjusting the inflow amount and the inflow speed of the gas from the inlet pipes 114 and 115, thereby further increasing the classification point. Adjustment is possible.
[0103]
The set distance is appropriately determined according to the characteristics of the powder raw material and the like, but the true density of the magnetic toner particles is 1.4 g / cm.^Three When the nonmagnetic toner particles exceed the above, the installation position of the classification edge block that can change the installation position each having the classification edge is set as follows.
L₀ > 0, L₁ > 0, L₂ > 0, L_Three > 0 L₀ <L_Three <L₁ + L₂
[In the formula, L₀ Indicates the height (mm) of the outlet of the raw material supply nozzle,
L₁ Indicates the distance (mm) between the side surface of the first classifying edge for fractionation into the middle powder group and the fine powder group, and the side surface of the Coanda block facing this,
L₂ Indicates the distance (mm) between the side surface of the first classification edge and the side surface of the second classification edge for fractionation into the coarse powder group and the medium powder group,
L_Three Is preferably set so as to satisfy the distance (mm) between the side surface of the second classifying edge and the side surface of the side wall facing it.
[0104]
When this condition is satisfied, magnetic toner particles having a sharp particle size distribution can be obtained efficiently.
[0105]
The airflow classifier is used by being connected to a device system by connecting devices with a communication means such as a pipe. A preferred example of such an apparatus system is shown in FIG. The integrated apparatus system shown in FIG. 12 connects the three-class classifier 1 (classifier shown in FIGS. 7 and 8), the quantitative feeder 202, the vibration feeder 203, and the collection cyclones 204, 205, and 206 by a communication means. It will be.
[0106]
In this apparatus system, the powder is fed to the fixed quantity feeder 202 by an appropriate means, and then introduced into the three-division classifier 201 through the vibration feeder 203 by the raw material supply nozzle 116. At the time of introduction, the powder is introduced into the three-division classifier 201 at a flow rate of 50 to 300 m / sec. Since the size of the classification chamber of the three-division classifier 201 is usually [10-50 cm] × [10-50 cm], the powder is instantly divided into three or more types of particles in 0.1 to 0.01 seconds or less. Can be classified. Then, it is classified into large particles (coarse particles), intermediate particles, and small particles by the three-division classifier 201. Thereafter, the large particles are sent and collected by the collection cyclone 206 through the discharge conduit 11a. The intermediate particles are discharged out of the system through the discharge conduit 112a and collected by the collection cyclone 205. The collection cyclones 204, 205, and 206 can also function as a suction pressure reducing means for sucking and introducing powder into the classification chamber via the raw material supply nozzle 116.
[0107]
An example of an image forming method using the magnetic toner of the present invention will be described with reference to FIG.
[0108]
The contact charging means 2 is applied with a voltage by the bias applying means E, charges the surface of the electrostatic charge image holding member (photosensitive drum) 1 to a negative polarity, and forms a digital latent image by image scanning by exposure 3 with laser light. Then, the latent image is reversely developed with the magnetic toner 13 of the developing device 4 including the toner carrying member (developing sleeve) 5 including the elastic blade 6 and the magnet. In the developing unit, the conductive substrate of the photosensitive drum 1 is grounded, and an alternating bias, a pulse bias, and / or a DC bias is applied to the developing sleeve 5 by a bias applying unit 8.
[0109]
When the transfer paper P is conveyed and arrives at the transfer section, the roller transfer means 9 charges the back surface of the transfer paper P (the surface opposite to the photosensitive drum side) with the voltage application means 10, thereby developing on the surface of the photosensitive drum 1. An image (toner image) is transferred onto the transfer paper P by the roller transfer means 9. The transfer paper P separated from the photosensitive drum 1 is subjected to a fixing process in order to fix the toner image on the transfer paper P by a heat and pressure roller fixing device 12.
[0110]
If there is little magnetic toner remaining on the photosensitive drum 1 after the transfer process, the cleaning process can be omitted. The process starting from the charging step by the contact charging unit 2 is repeated on the photosensitive drum 1 after being cleaned by the cleaning unit 11.
[0111]
The photosensitive drum has a photosensitive layer and a conductive substrate and moves in the direction of the arrow. A developing sleeve 5 of a non-magnetic cylinder, which is a toner carrier, rotates to advance in the same direction as the surface of the photosensitive drum 1 in the developing portion. Inside the developing sleeve 5, a multi-pole permanent magnet (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The magnetic toner 13 in the developing device 4 is applied on the nonmagnetic cylindrical surface, and the magnetic toner is given, for example, negative triboelectric charge by friction between the surface of the developing sleeve 5 and the magnetic toner. Further, the magnetic blade 6 is made thin (30 μm to 300 μm) by placing the elastic blade 6 close to the cylindrical surface (interval 50 μm to 500 μm) and disposing one of the multipolar permanent magnets opposite the magnet position. In addition, a magnetic toner layer that is thinner than the gap between the photosensitive drum 1 and the developing sleeve 5 in the developing portion is formed with uniform regulation. By adjusting the rotation speed of the developing sleeve 5, the sleeve surface speed is made substantially equal to or close to the speed of the photosensitive drum surface. An iron blade may be used as the elastic blade 6.
[0112]
An AC bias or a pulse bias may be applied to the developing sleeve 5 by the bias means 8 in the developing unit. The AC bias may be such that f is 200 to 4,000 Hz and Vpp is 500 to 3,000 V.
[0113]
When the magnetic toner is transferred in the developing unit, the magnetic toner is transferred to the electrostatic image side by the action of electrostatic and AC bias or pulse bias on the surface of the photosensitive drum.
[0114]
The elastic blade 6 is made of an elastic material such as silicone rubber, and the thickness of the magnetic toner layer is regulated by pressing with the elastic blade 6 and the magnetic toner 13 is applied on the developing sleeve 5.
[0115]
FIG. 5 is a configuration diagram of a charging roller which is an embodiment of the contact charging unit preferably used in the present invention.
[0116]
Reference numeral 42 denotes a charging roller, which basically comprises a central core metal 42a, a conductive elastic layer 42b that forms the outer periphery thereof, and a surface layer 42c. The charging roller 42 is pressed against the surface of the photosensitive drum 1 with a pressing force, and is driven to rotate as the photosensitive drum 1 rotates. The photosensitive drum 1 includes a conductive base layer 1a formed of a conductive metal such as aluminum and a photoconductive layer 1b formed on the outer surface thereof as basic constituent layers, and has a predetermined peripheral speed in the clockwise direction in the drawing. It is rotated at (process speed). A voltage is applied to the charging roller 42 by the bias applying means E, and a bias is applied to the charging roller 42 to charge the surface of the photosensitive drum to a predetermined polarity / potential. Next, an electrostatic charge image is formed by image exposure, and the electrostatic charge image is sequentially visualized as a toner image by the developing means.
[0117]
As a preferable process condition when using a charging roller, when a contact pressure of the roller is 5 to 500 g / cm and an AC voltage is superimposed on a DC voltage, AC voltage = 0.5 to 5 kVpp, AC frequency = 50 Hz to 5 kHz, DC voltage = ± 0.2 to ± 5 kV, and when only DC voltage is used, DC voltage = ± 0.2 to ± 5 kV.
[0118]
The material of the charging roller is preferably a conductive rubber such as ethylene-propylene-diene terpolymer (EPDM), and a release coating may be provided on the surface thereof. As the releasable film, nylon resin, polyvinylidene fluoride (PVDF), and polyvinylidene chloride (PVDC) are preferably used.
[0119]
Next, the process cartridge of the present invention will be described with reference to FIG.
[0120]
The process cartridge of the present invention is a cartridge in which at least developing means and a latent image holding member are generally formed into a cartridge, and is configured to be detachable from an image forming apparatus main body (for example, a copying machine, a laser beam printer, a facsimile machine). Has been.
[0121]
In the embodiment shown in FIG. 6, the developing unit 709, the drum-shaped electrostatic image holding member (photosensitive drum) 1, the cleaning unit 708 having the cleaning blade 708a, and the contact charging unit 742 as the primary charging unit are integrated. A cartridge 750 is illustrated.
[0122]
In the present embodiment, the developing unit 709 has an elastic regulating blade 711 as a toner layer thickness regulating unit and a magnetic toner 710 in the toner container 760, and uses the magnetic toner 710, and a developing bias from a bias applying unit at the time of development. A predetermined electric field is formed between the photosensitive drum 1 and the developing sleeve 704 as a toner carrier by the voltage, and the developing process is performed. In order to carry out this developing process suitably, the distance between the photosensitive drum 1 and the developing sleeve 704 is adjusted.
[0123]
In the above description, the embodiment in which the four constituent elements of the developing unit 709, the latent image holding body 1, the cleaning unit 708, and the primary charging unit 742 are integrated into a cartridge has been described. However, in the present invention, the developing unit and the electrostatic charge are combined. It is sufficient that at least two components with the image carrier are integrally formed into a cartridge, and the three components of the developing means, the electrostatic charge image holding body and the cleaning means, the developing means, the electrostatic charge image holding body, and Three components of the primary charging means or other components can be added to form a cartridge integrally.
[0124]
【Example】
The present invention will be described more specifically based on the following examples.
[0125]
Example 1
(I) Binder resin 100 parts by weight
(A) Styrene-n-butyl acrylate copolymer (copolymerization weight ratio = 80: 20)
(B) GPC has a main peak at a molecular weight of 15,000 and a sub-peak at a molecular weight of 650,000.
(C) Weight average molecular weight (Mw) 250,000
[0126]
(Ii) 100 parts by weight of magnetic fine powder
(A) Number average particle diameter R: 0.18 μm
(B) Shape of magnetic fine particles: spherical
(C) σ_r : 5.9 [Am² / Kg]
(D) H_C : 6.4 [kA / m]
(E) σ_r × H_C : 38 [kA² m / kg]
(F) W of silicon dioxide existing on the back surface of the magnetic fine particles: 0.13% by weight
(G) W × R: 0.024
[0127]
(Iii) 2 parts by weight of negative charge control agent
(A) Monoazo complex represented by the formula (a)
[0128]
[Outside 7]

[0129]
(Iv) 5 parts by weight of wax
(A) Long chain alkyl alcohol
(B) Average number of carbons: 50
(C) Softening point: 98 ° C
(E) Softening point measurement method: DSC endothermic peak temperature
[0130]
The above materials are mixed with a Henschel mixer to obtain a mixture. The obtained mixture is introduced into a biaxial extruder (model name “TEM-100B” manufactured by Toshiba Machine Co., Ltd.), and the mixture is mixed under the kneading conditions B shown in Table 1. Melt kneading was performed. The temperature of the kneaded material immediately after kneading was 159 ° C. The kneaded product was coarsely pulverized to 1 mm or less with a hammer mill, and the obtained coarsely pulverized product was finely pulverized with a collision-type airflow pulverizer using a jet stream to obtain a finely pulverized product.
[0131]
In the classification system shown in FIG. 12, the obtained finely pulverized product is supplied through the feeder 202 and through the vibratory feeder 203 and the raw material supply pipe 116 at a rate of 360 kg / h using the Coanda effect, In order to classify into three types of medium powder group M and fine powder group F, it was introduced into a multi-division classifier 201 shown in FIG.
[0132]
At the time of introduction, the suction force derived from the pressure reduction in the system due to the suction pressure reduction of the collection cyclones 204, 205, 206 communicating with the discharge ports 111, 112, 113 and the ink jet nozzle 131 attached to the raw material supply pipe 116. Air compression (pressure 1.5kg / cm² ) Was used.
[0133]
In order to change the shape of the classification area, each set distance shown in FIG. 11 was set as follows, and classification was performed.
L₀ = 6 mm (height diameter of raw material supply nozzle outlet 116a)
L₁ = 32 mm (distance between the side surface of the classification edge 117 and the side surface of the Coanda block 126)
L₂ = 33 mm (distance between the side surface of the classification edge 117 and the side surface of the classification edge 118)
L_Three = 39 mm (distance between the side surface of the classification edge 118 and the side surface of the side wall 123)
L_Four = 18 mm (distance between the tip of the classification edge 117 and the side surface of the Coanda block 126)
L_Five = 33 mm (distance between the tip of the classification edge 118 and the side surface of the Coanda block 126)
L₆ = 25 mm (distance between the tip of the inlet edge 119 and the side surface of the Coanda block 126)
R = 14 mm (the radius of the ridge of the Coanda block 126)
[0134]
The finely pulverized product introduced was classified instantly for 0.1 seconds or less.
[0135]
Medium powder group M used as magnetic toner particles has a weight average particle diameter (D_Four ) Is 5.7 μm, the absorbance is 0.55, the shape factor SF-1 is 154, the shape factor SF-2 is 143, and the value of SF-1 / SF-2 is 1.08. Met. Table 2 shows the physical properties of the obtained magnetic toner particles. Further, Table 3 shows the dispersion state of the magnetic fine powder and the dispersion state of the wax.
[0136]
Hydrophobic silica fine powder (BET specific surface area 110 m) surface-treated with 100 parts by weight of the obtained magnetic toner particles, a silane coupling agent and dimethyl silicone oil² / G) 1.5 parts by weight was mixed to prepare a negative triboelectrically chargeable magnetic toner.
[0137]
For the evaluation of magnetic toner by the image forming method shown in FIG. 4, for a laser beam printer (trade name LBP-450, manufactured by Canon Inc.) that develops an electrostatic charge image by a reversal development method having a resolution of 600 dpi. Magnetic toner was introduced into the developing device of the process cartridge, and the process cartridge was mounted on a laser beam printer, and an image output test was performed in each environment.
[0138]
Furthermore, the image quality of the dot latent image was evaluated using a laser beam printer modified to have a resolution of 1200 dpi.
[0139]
The evaluation results are shown in Table 4, Table 5, and Table 6.
[0140]
Evaluation methods
(A) Image density
The image density of the solid black images at the initial stage (second sheet), the 3000th sheet, and the 6000th sheet was measured with a Macbeth densitometer.
[0141]
(B) Fog
Using a “reflector meter” (Tokyo Denshoku Co., Ltd.), measure the whiteness of the transfer paper before printing, determine the difference from the whiteness of the printed white image area, and maximize the difference. showed that.
[0142]
(C) Charging roller dirt
Evaluation was performed using a halftone image in which a defectively charged image is likely to occur after the endurance of 6000 sheets.
Rank 5: No defective image is generated due to contamination of the contact charging roller.
Rank 3: Generation of a defective image due to contamination of the contact charging roller is confirmed, but it does not cause a practical problem.
Rank 1: Generation of a defective image due to contamination of the contact charging roller is confirmed, and the defective image becomes a practical problem.
Rank 4 is an intermediate level between ranks 5 and 3, and rank 2 is an intermediate level between ranks 3 and 1.
[0143]
(D) 600 dpi dot image
A one-dot toner image was formed under image forming conditions capable of forming 600 dot latent images per inch, and the toner image was enlarged and visually evaluated in four stages.
A: Excellent
B: Good
C: Normal
D: Poor (toner splattering occurs or dot image shape is irregular)
[0144]
(E) 1200 dpi dot image
A one-dot toner image was formed under image forming conditions capable of forming 1200 dot latent images per inch, and the toner image was enlarged and visually evaluated in four stages.
A: Excellent
B: Good
C: Normal
D: Poor (toner splattering occurs or dot image shape is irregular)
[0145]
(F) Drum fusion
The evaluation was based on the degree of occurrence of white spots caused by deposits on the OPC photosensitive drum generated on the solid black image after the endurance of 6000 sheets.
Rank 5: None occurred.
Rank 3: Although several points are observed, there is no practical problem.
Rank 1: There are many occurrences (tens of points), and there are practical problems.
Rank 4 is an intermediate level between ranks 5 and 3, and rank 2 is an intermediate level between ranks 3 and 1.
[0146]
(G) Morning image density
The solid black image density of the first image (corresponding to 3001 images) in the morning of the third day was measured at 1500 sheets / day in a high temperature and high humidity environment.
[0157]
  Examples 11, 13 and 14, Reference Examples 1 and 2
  Magnetic toner particles shown in Table 2 were obtained by changing the magnetic fine powder to be used, kneading conditions, classification conditions and the like. The obtained magnetic toner particles and hydrophobic silica fine powder were mixed to prepare a magnetic toner, and image output evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 4, Table 5, and Table 6.
[0158]
Comparative Example 1
A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to G shown in Table 1. The absorbance of the magnetic toner particles in the wettability test was 0.72, SF-1 = 155, SF-2 = 144, and the temperature of the kneaded product was 152 ° C. The results are shown in Table 2.
[0159]
Comparative Example 2
A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to H shown in Table 1. The absorbance of the magnetic toner particles was 0.77, SF-1 = 155, SF-2 = 143, and the temperature of the kneaded material was 153 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Table 4, Table 5, and Table 6.
[0160]
Comparative Example 3
A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to I shown in Table 1. The absorbance of the magnetic toner particles was 0.18, SF-1 = 155, SF-2 = 143, and the temperature of the kneaded product was 160 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Table 4, Table 5, and Table 6.
[0161]
Comparative Examples 4 to 6
Magnetic toner particles shown in Table 2 were obtained by changing the magnetic fine powder to be used, kneading conditions, classification conditions and the like. The obtained magnetic toner particles and hydrophobic silica fine powder were mixed to prepare a magnetic toner, and image output evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 4, Table 5, and Table 6.
[0162]
[Table 1]

[0163]
[Table 2]

[0164]
[Table 3]

[0165]
[Table 4]

[0166]
[Table 5]

[0167]
[Table 6]

[0182]
【The invention's effect】
The magnetic toner of the present invention uses magnetic toner particles having specific wettability, so that the concentration is high even in a low temperature / low humidity environment, there is little fogging, no charging roller contamination occurs, and there is no high temperature / high humidity environment. Also, it is possible to provide an image having a high density without causing drum fusion.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a temperature control unit configuration and a shaft configuration of a kneader.
FIG. 2 is a schematic explanatory diagram of a cross-sectional configuration of a cylinder.
FIG. 3 is a correlation diagram between the resin temperature, the amount of free magnetic fine particles, and the dispersibility of wax.
FIG. 4 is a schematic explanatory view of an example of an electrophotographic apparatus using the magnetic toner of the present invention.
FIG. 5 is a schematic explanatory diagram of contact charging means preferably used in the present invention.
FIG. 6 is a schematic explanatory view showing an example of a process cartridge of the present invention.
FIG. 7 is a schematic cross-sectional view of an airflow classifier using the Coanda effect for multi-classification of magnetic toner particles.
8 is a perspective view of the airflow classifier shown in FIG.
9 is a perspective view of the airflow classifier shown in FIG.
10 is a cross-sectional view taken along line AA ′ in FIG.
11 is a diagram showing a main part of FIG. 7;
FIG. 12 is an explanatory diagram showing an example of a classification process used for classification of magnetic toner particles.
[Explanation of symbols]
1 Electrostatic charge image carrier
2 Primary charging device
3 Exposure optical system
4 Development device
5 Toner carrier
6 Toner layer thickness regulating member
7 Toner stirring means
8 Development bias power supply
9 Transfer device
10 Transfer current generator
11 Cleaning means
12 Fixing device
13 Magnetic toner
704 Development sleeve
709 Developer
710 Developer (Magnetic Toner)
742 Contact charging means
743 Bias applying means

Claims (35)

A magnetic toner for developing an electrostatic image having magnetic toner particles containing at least a binder resin, a magnetic fine powder, and a long-chain alkyl alcohol wax;
The magnetic toner particles are prepared by mixing a mixture containing at least a binder resin, magnetic fine powder and a long-chain alkyl alcohol wax with a kneading machine using the following kneading conditions.
2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ^{4
E = kω 2 T, ε =} F / (πD 2 L)
(Wherein, ω represents the screw rotation speed (m / min), T represents the set temperature (K), F represents the supply amount of the mixture (kg / min), and D represents the cylinder inner diameter (m). , L represents the screw effective length (m), π represents the circumference, k represents (D ₀ / D) ² , and D ₀ is 0.1 m.)
It is manufactured by melt-kneading so as to satisfy
The magnetic fine powder is contained in the magnetic toner particles in an amount of 40 to 60% by weight,
The magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm; the wavelength of a dispersion liquid in which 15 mg of the magnetic toner particles are dispersed in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73). A magnetic toner for developing electrostatic images, wherein the absorbance at 600 nm is 0.35 to 0.69 . The magnetic fine powder has a product (σ _r × H) of residual magnetization (σ _r (Am ² / kg)) and coercive force (H _C (kA / m)) under a magnetic field of 795.8 kA / m (10 k Oersted). the magnetic toner according to claim 1 _C) is ^{24~56 (kA 2 m / kg)} . Long-chain alkyl alcohol wax [wherein, n represents an integer of 20-300] structural formula _CH 3 _{(CH 2)} n OH magnetic toner according to claim 1 or 2 having a. The magnetic toner particles, the value of shape factor SF-1 is the 140 <SF-1 ≦ 180, either the value of shape factor SF-2 of 130 <of claims 1 to 3 is a SF-2 ≦ 170 magnetic toner. Magnetic fine powder, the residual magnetization (sigma _r) and coercivity _{(H C)} and the product (σ _r × _{H C)} is 30~52 ^(kA 2 m / kg) either of claims 1 to 4 which is Magnetic toner. Magnetic fine powder, either of the magnetic toner of claims 1 to 5 the number average particle diameter of 0.05～0.30Myuemu. Magnetic fine powder, 0.008 ≦ W × either magnetic toner R ≦ 0.035 Conditions 1 to claim satisfies the 6. Magnetic fine powder, either of the magnetic toner according to claim 1 to 7 is contained in 45 to 55 wt% magnetic toner particles by weight of the magnetic toner particles. The magnetic toner particles, either magnetic toner according to claim 1 to 8 is mixed with a BET specific surface area of 30 m 2 / ^g or more inorganic fine powder. The magnetic toner according to claim 9 , wherein the inorganic fine powder has a BET specific surface area of 50 to 400 m ² / g. The magnetic toner according to claim 9 or 10 , wherein the magnetic toner particles are mixed with 0.01 to 8 parts by weight of inorganic fine powder per 100 parts by weight. One of the magnetic toner according to claim 9 or 11 inorganic fine powder is a silica fine powder has been treated with a silicone oil. A method for producing a magnetic toner having magnetic toner particles containing at least a binder resin, magnetic fine powder, and a long-chain alkyl alcohol wax,
A mixture having at least a binder resin, a magnetic fine powder, and a long-chain alkyl alcohol wax is mixed with a kneader under the following conditions: 2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ⁴
E = kω ² T
ε = F / (πD ² L)
[In the formula, ω represents the screw rotation speed (m / min), T represents the set temperature (K), F represents the supply amount of the mixture (kg / min), and D represents the cylinder inner diameter (m). , L represents the screw effective length (m), π represents the circumference, k represents (D ₀ / D) ² , and D ₀ is 0.1 m. ]
In melting and kneading, the kneaded product was cooled, the cooled product was pulverized, and a step of obtaining a magnetic toner particles pulverized product was classified,
The magnetic toner particles contain 40 to 60% by weight of the magnetic fine powder;
The magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm; the wavelength of a dispersion liquid in which 15 mg of the magnetic toner particles are dispersed in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73). A method for producing a magnetic toner, wherein the absorbance at 600 nm is 0.35 to 0.69 . The screw rotation speed ω (m / min) of the kneader is 5 to 50, the set temperature T (K) is 333 to 513, and the supply amount F (kg / min) of the mixture is 0.15 to 25. There, a cylinder inner diameter D (m) is 0.03 to 0.2, the method of manufacturing a magnetic toner according to claim 13 effective length of screw L (m) is from 1.00 to 4.00. The value of E is 3.0 × 10 ^{5 to} 16.0 × 10 ⁵ , the screw rotation speed ω (m / min) of the kneader is 5 to 50, and the set temperature T (K) is 333 to 513. The feed amount F (kg / min) of the mixture is 0.15 to 25, the inner diameter D (m) of the cylinder is 0.03 to 0.2, and the effective length L (m) of the screw is 1. The method for producing a magnetic toner according to claim 13 or 14 , wherein the method is 0.00 to 4.00. 16. The method for producing a magnetic toner according to claim 14 , wherein the supply amount F of the mixture is 0.30 to 12.00 (kg / min). any of a method of manufacturing a magnetic toner according to claim 13 or 16 values are 85 to 130 of the epsilon. The value of E / epsilon is, 2.5 × 10 ³ to 1.5 × 10 ⁴ the method of any one of the magnetic toner of claims 13 to 17. The screw rotation speed ω (m / min) of the kneader is 5 to 50, the set temperature T (K) is 333 to 513, and the supply amount F (kg / min) of the mixture is 0.15 to 25. Yes, the inner diameter D (m) of the cylinder is 0.03 to 0.2, the effective length L (m) of the screw is 1.00 to 4.00, and the value of E is 3.0 × 10 ^{5 to} 16.0 × 10 ⁵ , the feed rate F of the mixture is 0.30 to 12.0 (kg / min), the value of ε is 85 to 130, and the value of E / ε is 2.5. one of the method of manufacturing a magnetic toner × 10 ³ to 1.5 × 10 is a ⁴ claims 13 to 18. The magnetic fine powder has a product (σ _r × H) of residual magnetization (σ _r (Am ² / kg)) and coercive force (H _C (kA / m)) under a magnetic field of 795.8 kA / m (10 k Oersted). _The method for producing a magnetic toner according to claim 13 , wherein _C ) is 24 to 56 (kA ² m / kg). The method for producing a magnetic toner according to claim 13, wherein the long-chain alkyl alcohol wax has a structural formula CH ₃ (CH ₂ ) _n OH, wherein n represents an integer of 20 to 300. The magnetic toner particles according to any one of claims 13 to 21 , wherein the shape factor SF-1 has a value of 140 <SF-1≤180 and the shape factor SF-2 has a value of 130 <SF-2≤170. Toner manufacturing method. Magnetic fine powder, the residual magnetization (sigma _r) and coercivity _{(H C)} and the product (σ _r × _{H C)} is 30~52 ^(kA 2 m / kg) of any one of claims 13 to 22 which is Manufacturing method of magnetic toner. Magnetic fine powder production method of any of the magnetic toner of claims 13 to 23 number average particle diameter of 0.05～0.30Myuemu. Magnetic fine powder, 0.008 ≦ W × method of any of the magnetic toner of R ≦ 0.035 claims 13 to 24 which satisfies the condition of. The method for producing a magnetic toner according to any one of claims 13 to 25 , wherein the magnetic fine powder is contained in 45 to 55 wt% of the magnetic toner particles based on the weight of the magnetic toner particles. The magnetic toner particles, any of a method for manufacturing a magnetic toner according to claim 13 or 26 is mixed with BET specific surface area 30 m 2 / ^g or more inorganic fine powder. 28. The method for producing a magnetic toner according to claim 27 , wherein the inorganic fine powder has a BET specific surface area of 50 to 400 m < ² > / g. The magnetic toner particles, method for producing a magnetic toner according to claim 27 or 28 is mixed with an inorganic fine powder of 0.01 to 8 parts by weight per 100 parts by weight. Any of a method of manufacturing a magnetic toner according to claim 27 or 29 inorganic fine powder is a silica fine powder has been treated with a silicone oil. The electrostatic charge image holding member is charged by a contact charging means to which a bias is applied, an electrostatic charge image is formed on the charged electrostatic charge image holding member by exposure, and the electrostatic charge image is developed by a developing means having magnetic toner. An image forming method for forming a magnetic toner image,
Image forming method, wherein said magnetic toner is the magnetic toner according to any one of claims 1 to 12. 32. The image forming method according to claim 31 , wherein the contact charging means is a charging roller. Magnetic toner image on the electrostatic image bearing member, a bias is transferred onto the transfer material by a transfer roller which is applied, the magnetic toner image on the transfer material according to claim 31 or is fixed by heat-and-pressure fixing means 32 Image forming method. An electrostatic charge image holding member, a contact charging means for charging the electrostatic charge image holding member, and a developing means for holding magnetic toner, and a process cartridge that is detachable from the image forming apparatus main body,
The process cartridge in which the magnetic toner, characterized in that it is a magnetic toner according to any one of claims 1 to 12. The process cartridge according to claim 34 , wherein the contact charging means is a charging roller.

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