JP4789363B2 - Dry magnetic toner and image forming method - Google Patents

Description

【００４８】

【００４９】
【数２】

【００５０】
本発明に用いている円形度はトナー粒子の凹凸の度合いの指標であり、トナーが完全な球形の場合１．００を示し、表面形状が複雑になるほど円形度は小さな値となる。また、本発明における円形度分布のＳＤは、バラツキの指標であり、数値が小さいほどトナー形状のバラツキが小さいことを表す。
【００５１】
本発明で用いている測定装置である「ＦＰＩＡ−１０００」は、各粒子の円形度を算出後、平均円形度及び円形度標準偏差の算出に当たって、得られた円形度によって、粒子を円形度０．４〜１．０を６１分割したクラスに分け、分割点の中心値と頻度を用いて平均円形度及び円形度標準偏差の算出を行う算出法を用いている。しかしながら、この算出法で算出される平均円形度及び円形度標準偏差の各値と、上述した各粒子の円形度を直接用いる算出式によって算出される平均円形度及び円形度標準偏差の誤差は、非常に少なく、実質的には無視できる程度であり、本発明においては、算出時間の短縮化や算出演算式の簡略化の如きデータの取り扱い上の理由で、上述した各粒子の円形度を直接用いる算出式の概念を利用し、一部変更したこのような算出法を用いても良い。
【００５２】
従来より、トナー形状がトナーの諸特性に影響を与えることが知られているが、本発明者らは、種々の検討によって３μｍ以上のトナーの形状と遊離した磁性酸化鉄粒子の量が転写性、現像性に大きく影響を与えていることを見出した。また、本発明者らは３μｍ未満の円相当径の粒子群がある一定量を超えると転写性、現像性を低下させる要因となることも見出した。粒径３μｍ未満のトナーの微粉や粒径３μｍ未満の外添剤がある量以上になった場合、粒径３μｍ以上のトナーの円形度をより高くしないと所望の性能を得にくいことが明らかとなった。
【００５３】
従って、本発明では、３μｍ以上の円相当径の粒子群についての円形度が本発明の効果を発現するために重要であるが、本発明において転写性と現像性に大きく影響を与える３μｍ以上のトナー粒子の円形度の作用をより効果的に発揮するためには、以下のように３μｍ以下の微粉の存在量により３μｍ以上のトナー粒子の円形度を制御する必要がある。
【００５４】
３μｍ以下の微粉の存在量により３μｍ以上のトナー粒子の円形度を制御することで、転写性，現像性の優れたトナーを得ることができる。
【００５５】
ＦＰＩＡ−１０００における円形度の測定においては、粒子径が小さくなるほど粒子像は点に近似するため、円形度は大きくなる傾向を示す。このため、粒子径が小さい粒子がトナー中に多量に存在すると、トナーの円形度は大きくなる。逆に、粒子径が小さい粒子がトナー中に少量しか存在しない場合、トナーの円形度は小さくなってしまう。そこで、下記式（３）により計算されたように全測定粒子の粒子濃度に対する３μｍ以上の円相当径の粒子群の粒子濃度の割合を１００％から差し引くことにより求めることで表されるカット率Ｚと、重量平均粒子径Ｘとの関係を式（２）または式（５）の２つに場合分けし、それぞれの場合における、所望の性能を満足するのに必要なトナーの円形度と重量平均粒子径との関係を、式（４）または式（６）のように導いた。
【００５６】
カット率Ｚ＝（１−Ｂ／Ａ）×１００ （３）
［式中、Ａは全測定粒子の粒子濃度を示し、Ｂは３μｍ以上の円相当径の粒子群の粒子濃度を示す］
【００５７】
３μｍ未満の粒子を少量含有するトナーにおいては、３μｍ以上の粒子において、円形度が０．９５０以上の粒子の個数基準の累積値Ｙは、重量平均径Ｘに対して、ｅｘｐ５．５１×Ｘ^-0.645（≒２４７．１５１×Ｘ^-0.645）以上であれば良いが、３μｍ未満の粒子を多量に含有するトナーにおいては、３μｍ以上の粒子において、円形度が０．９５０以上の粒子の個数基準の累積値Ｙは、重量平均径Ｘに対して、より大きめのｅｘｐ５．３７×Ｘ^-0.545以上にする必要がある。
【００５８】
本発明のトナーは該トナーの３μｍ以上の粒子における円形度ａが０．９００以上の粒子を個数基準の累積値で９０個数％以上含有し、且つ円形度ａが０．９５０以上の粒子が個数基準の累積値で、ａ）カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ≦５．３×Ｘ（好ましくは０＜カット率Ｚ≦５．３×Ｘ）の式を満たす場合、個数基準累積値Ｙ≧ｅｘｐ５．５１×Ｘ^-0.645を満足することが好ましい。
【００５９】
或いは、本発明のトナーは該トナーの３μｍ以上の粒子における円形度ａが０．９００以上の粒子を個数基準の累積値で９０％以上含有し、且つ円形度ａが０．９５０以上の粒子が個数基準の累積値で、ｂ）カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ＞５．３×Ｘ（好ましくは９５≧カット率Ｚ＞５．３×Ｘ）の式を満たす場合、
個数基準累積値Ｙ≧ｅｘｐ５．３７×Ｘ^-0.545を満足することが好ましい。
［但し、カット率Ｚは、東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００で測定される全測定粒子の粒子濃度Ａ（個数／μｌ）、円相当径３μｍ以上の測定粒子濃度Ｂ（個数／μｌ）とした時、式（３）で表され、
Ｚ＝（１−Ｂ／Ａ）×１００ （３）
トナー重量平均粒子径Ｘは５．０〜１２．０μｍである。］
【００６０】
このような円形度をトナーが有する場合、トナーは帯電コントロールが容易で帯電の均一化と帯電の耐久安定性を達成できる。さらに、上記のような円形度を有する場合、転写効率が高くなることが判明した。これは、上述されたような円形度を有するトナーの場合、トナー粒子と感光体との接触面積が小さくなりファンデルワールス力等に起因するトナー粒子の感光体への付着力が低下するためであると考えられる。さらに、従来の衝突式気流粉砕機によって粉砕されたトナーと比較して、この様なトナー粒子は比表面積が小さいので、トナー粒子間の接触面積が減少し、トナー粉体の嵩密度は密となり、定着時の熱伝導を良くすることができ定着性向上の効果も得ることが出来る。
【００６１】
さらに該トナーの３μｍ以上の粒子における円形度ａが０．９００以上の粒子の存在が個数基準の累積値で９０％未満となる場合には、トナーのチャージのリークが遊離した磁性酸化鉄粒子をとおして起こり易くなり、遊離磁性酸化鉄粒子の量を制御しても結果としてトナーの帯電量が低下してしまうことがある。また、トナー粒子と感光体との接触面積が大きくなり、トナー粒子の感光体への付着力が増すため、十分な転写効率を得にくくなる。
【００６２】
また、該トナーの３μｍ以上の粒子における円形度ａが０．９５０以上の粒子が個数基準の累積値で、ａ）カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ≦５．３×Ｘ（好ましくは０＜カット率Ｚ≦５．３×Ｘ）の式を満たし、
個数基準累積値Ｙ≧ｅｘｐ５．５１×Ｘ^-0.645を満足しない場合、即ち、
個数基準累積値Ｙ＜ｅｘｐ５．５１×Ｘ^-0.645を満足するような場合；或いは、該トナーの３μｍ以上の粒子における円形度ａが０．９５０以上の粒子が個数基準の累積値で、ｂ＞カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ＞５．３×Ｘ（好ましくは９５≧カット率Ｚ＞５．３×Ｘ）の式を満たし、
個数基準累積値Ｙ≧ｅｘｐ５．３７×Ｘ^-0.545を満足しない場合、例えば、
個数基準累積値Ｙ＜ｅｘｐ５．３７×Ｘ^-0.545を満足するような場合には、十分な転写効率が得られないだけでなくトナーの流動性も低下する傾向であり、さらには所望の定着性能も得にくいものである。
【００６３】
また、特定の円形度を有するトナーを製造する場合、重量平均径が５〜１２μｍであることが好ましい。
【００６４】
更に好ましくは、重量平均径が５〜１０μｍであり、粒径４．０μｍ以下の粒子が４０個数％以下であり、粒径１０．１μｍ以上の粒子が２５体積％以下であるトナーであることがよい。
【００６５】
重量平均径が１２μｍを上回るトナーを得る場合には、粉砕機内での負荷を極力減らすか、処理量を多くすることで粒径的には対応可能であるが、形状は角張ったものとなり、所望の円形度にすることは難しく、更に所望の円形度分布にすることは難しくなる。
【００６６】
重量平均径が５μｍを下回るトナーを得る場合には、粉砕機内での負荷を増大させるか、処理量を極端に少なくすることで対応は可能であるが、形状は球形に近似し所望の円形度にすることは難しく、更に所望の円形度分布にすることは難しくなるばかりでなく、微粉、超微粉の発生を押さえ切れなくなる。
【００６７】
本発明のトナーは該トナーの３μｍ以上の粒子における円形度ａが０．９００以上の粒子を個数基準の累積値で９０％以上含有し、且つ円形度ａが０．９５０以上の粒子が個数基準の累積値で、ａ）カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ≦５．３×Ｘ（好ましくは０＜カット率Ｚ≦５．３×Ｘ）の式を満たす場合
個数基準累積値Ｙ≧ｅｘｐ５．５１×Ｘ^-0.645を満足することを特徴とし、より好ましくは
個数基準累積値ｅｘｐ４．８５×Ｘ^-0.187≧Ｙ＜ｅｘｐ５．５１×Ｘ^-0.645である。
或いは、本発明のトナーは該トナーの３μｍ以上の粒子における円形度ａが０．９５０以上の粒子が個数基準の累積値で、ｂ）カット率Ｚとトナー重量平均径Ｘの関係がカット率Ｚ＞５．３×Ｘ（好ましくは９５≧カット率Ｚ＞５．３×Ｘ）の式を満たす場合、
個数基準累積値ｅｘｐ４．８５×Ｘ^-0.187≧Ｙ≧ｅｘｐ５．３７×Ｘ^-0.545である。
このような円形度を有する場合、帯電コントロールが容易で帯電の均一化と帯電の耐久安定性のあるトナーを得ることができる。さらに、上記のような円形度を有する場合、転写効率を高くすることができる。これは上述されたような円形度を有するトナーの場合、トナー粒子と感光体との接触面積が小さくなりファンデルワールス力等に起因するトナー粒子の感光体への付着力が低下するためであると考えられる。さらに、従来の衝突式気流粉砕機によって粉砕されたトナーと比較して、トナー粒子の比表面積が低減されているため、トナー粒子間の接触面積が減少し、トナー粉体の嵩密度は密となり、定着時の熱伝導を良くすることができ定着性向上の効果も得ることが出来る。
【００６８】
粒径４．０μｍ以下の粒子が４０個数％を超えるトナーを得る場合も、粉砕機内での負荷を増大させるか、処理量を極端に少なくすることで対応は可能であるが、形状は球形に近似し所望の円形度にすることは難しく、更に所望の円形度分布にすることは難しくなる。
【００６９】
粒径１０．１μｍ以上の粒子が２５体積％を超えるトナーを得る場合、粉砕機内での負荷を極力減らすか、処理量を多くすることで粒径的には対応可能であるが、形状は角張ったものとなり、所望の円形度にすることは難しく、更に所望の円形度分布にすることは難しくなる。
【００７０】
このような各円形度を有する粒子のバラツキの一つの目安として、円形度標準偏差ＳＤを用いることもできる。本発明においては円形度標準偏差ＳＤが０．０３０乃至０．０４５であれば問題は無い。
【００７１】
具体的な測定方法としては、予め容器中の不純物を除去した水１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルフォン酸塩）を０．１〜０．５ｍｌ加え、更に測定試料を０．１〜０．５ｇ程度加える。試料を分散した懸濁液は超音波（５０ｋＨｚ，１２０Ｗ）を１〜３分間照射し、分散液濃度を１．２〜２．０万個／μｌとして、上記フロー式粒子像測定装置を用い、０．６０μｍ以上１５９．２１μｍ未満の円相当径を有する粒子の円形度分布を測定する。分散液濃度を１．２〜２．０万個／μｌとすることで、カット率が大きくなった場合でも装置の精度が保てるだけの粒子濃度を維持することができる。
【００７２】
測定の概略は、東亜医用電子社（株）発行のＦＰＩＡ−１０００のカタログ（１９９５年６月版）、測定装置の操作マニュアル及び特開平８−１３６４３９号公報に記載されている。以下に測定方法を説明する。
【００７３】
試料分散液は、フラットで扁平なフローセル（厚み約２００μｍ）の流路（流れ方向に沿って広がっている）を通過させる。フローセルの厚みに対して交差して通過する光路を形成するように、ストロボとＣＣＤカメラが、フローセルに対して、相互に反対側に位置するように装着される。試料分散液が流れている間に、ストロボ光がフローセルを流れている粒子の画像を得るために１／３０秒間隔で照射され、その結果、それぞれの粒子は、フローセルに平行な一定範囲を有する２次元画像として撮影される。それぞれの粒子の２次元画像の面積から、同一の面積を有する円の直径を円相当径として算出する。それぞれの粒子の２次元画像の投影面積及び投影像の周囲長から上記の円形度算出式を用いて各粒子の円形度を算出する。
【００７４】
次に、本発明のトナーに使用される結着樹脂に関して説明する。
【００７５】
本発明で用いられる結着樹脂の酸価は１〜１００ｍｇＫＯＨ／ｇであることが好ましく、さらに好ましくは１〜５０ｍｇＫＯＨ／ｇが良く、特には２〜４０ｍｇＫＯＨ／ｇであることが好ましい。
【００７６】
このような酸価の範囲を有しない場合、トナー製造時の混練工程においてトナー原材料、特に磁性酸化鉄粒子の分散状態が悪化し、粉砕工程において遊離磁性酸化鉄粒子が増加しやすい。
【００７７】
結着樹脂の酸価が１ｍｇＫＯＨ／ｇ未満の場合は、トナー粒子の帯電性が低下し、現像性や耐久安定性を低下させる。一方、１００ｍｇＫＯＨ／ｇを超える場合は結着樹脂の吸湿性が強くなり、画像濃度が低下し、カブリが増加する傾向がある。
【００７８】
本発明において、結着樹脂の酸価は以下の方法により求める。
【００７９】
酸価の測定
基本操作はＪＩＳ Ｋ−００７０に準ずる。
１）結着樹脂の粉砕品０．５〜２．０（ｇ）を精秤し、結着樹脂の重さＷ（ｇ）とする。
２）３００（ｍｌ）のビーカーに試料を入れ、トルエン／エタノール（４／１）の混合液１５０（ｍｌ）を加え溶解する。
３）０．１規定のＫＯＨのメタノール溶液を用いて、電位差滴定装置を用いて滴定する（例えば、京都電子株式会社製の電位差滴定装置ＡＴ−４００（ｗｉｎ ｗｏｒｋｓｔａｔｉｏｎ）とＡＢＰ−４１０電動ビュレットを用いての自動滴定が利用できる。）
４）この時のＫＯＨ溶液の使用量Ｓ（ｍｌ）とし、同時にブランクを測定しこの時のＫＯＨ溶液の使用量をＢ（ｍｌ）とする。
５）次式により酸価を計算する。ｆはＫＯＨのファクターである。
【００８０】
酸価（ｍｇＫＯＨ／ｇ）＝（（Ｓ−Ｂ）×ｆ×５．６１）／Ｗ
【００８１】
結着樹脂としては、カルボキシル基又は酸無水物基を有するビニル系重合体、ポリエステル樹脂等を用いることができる。
【００８２】
結着樹脂として使用するビニル系重合体を生成するためのモノマーとして以下のものが挙げられる。
【００８３】
例えば、マレイン酸、シトラコン酸、ジメチルマレイン酸、イタコン酸、アルケニルコハク酸、フマル酸、メタコン酸、ジメチルフマル酸の如き不飽和二塩基酸及びそれらの無水物。更に上記不飽和二塩基酸のモノエステル。また、アクリル酸、メタクリル酸、クロトン酸、ケイヒ酸の如きα，β−不飽和酸及びこれらの無水物；上記α，β−不飽和二塩基酸と上記α，β−不飽和モノ酸との無水物及び、上記不飽和酸と低級脂肪酸との無水物。アルケニルマロン酸、アルケニルグルタル酸、アルケニルアジピン酸及びこれらの無水物及びこれらのモノエステル。これらの中でも、マレイン酸、マレイン酸ハーフエステル、マレイン酸無水物が本発明の結着樹脂を得るモノマーとして特に好ましく用いられる。
【００８４】
更にビニル重合体を生成するためのコモノマーとしては、次のようなものが挙げられる。
【００８５】
例えばスチレン；ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、ｐ−メトキシスチレン、ｐ−フェニルスチレン、ｐ−クロルスチレン、３，４−ジクロルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｎ−ブチルスチレン、ｐ−ｔｅｒｔ−ブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレンの如きスチレン誘導体；エチレン、プロピレン、ブチレン、イソブチレンの如きエチレン不飽和モノオレフィン類；ブタジエンの如き不飽和ポリエン類；塩化ビニル、塩化ビニリデン、臭化ビニル、沸化ビニルの如きハロゲン化ビニル類；酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニルの如きビニルエステル類；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、メタクリル酸−２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸フェニル、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如きα−メチレン脂肪族モノカルボン酸エステル類；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチル、アクリル酸イソブチル、アクリル酸プロピル、アクリル酸ｎ−オクチル、アクリル酸ドデシル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸２−クロルエチル、アクリル酸フェニルの如きアクリル酸エステル類；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如きビニルエーテル類；ビニルメチルケトン、ビニルヘキシルケトン、メチルイソプロペニルケトンの如きビニルケトン類；Ｎ−ビニルピロール、Ｎ−ビニルカルバゾール、Ｎ−ビニルインドール、Ｎ−ビニルピロリドンの如きＮ−ビニル化合物；ビニルナフタリン；アクリロニトリル、メタクリロニトリル、アクリルアミドの如きアクリル酸誘導体もしくはメタクリル酸誘導体；前述のα，β−不飽和酸のエステル、二塩基酸のジエステル類。これらのビニル系モノマが単独もしくは２つ以上で用いられる。
【００８６】
これらの中でも、スチレン系共重合体、スチレン−アクリル系共重合体となるようなモノマーの組み合わせが好ましい。
【００８７】
また架橋性モノマーとしては、主として２個以上の重合可能な二重結合を有するモノマーが用いられる。
【００８８】
本発明に用いられる結着樹脂は、必要に応じて以下に例示する様な架橋性モノマーで架橋された重合体であってもよい。
【００８９】
芳香族ジビニル化合物（例えば、ジビニルベンゼン、ジビニルナフタレン等）；アルキル鎖で結ばれたジアクリレート化合物類（例えば、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート及び以上の化合物のアクリレートをメタアクリレートに代えたもの）；エーテル結合を含むアルキル鎖で結ばれたジアクリレート化合物類（例えば、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコール＃４００ジアクリレート、ポリエチレングリコール＃６００ジアクリレート、ジプロピレングリコールジアクリレート及び以上の化合物のアクリレートをメタアクリレートに代えたもの）；芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類（例えば、ポリオキシエチレン（２）−２，２−ビス（４−ヒドロキジフェニル）プロパンジアクリレート、ポリオキシエチレン（４）−２，２−ビス（４−ヒドロキジフェニル）プロパンジアクリレート及び、以上の化合物のアクリレートをメタアクリレートに代えたもの）；ポリエステル型ジアクリレート化合物類（例えば、商品名ＭＡＮＤＡ（日本化薬））が挙げられる。多官能の架橋剤としては、ペンタエリスリトールトリアクリレート、トリメチロールエタントリアクリレート、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート及び以上の化合物のアクリレートをメタアクリレートに代えたもの；トリアリルシアヌレート、トリアリルトリメリテートが挙げられる。
【００９０】
これらの架橋剤は、他のモノマー成分１００質量部に対して、０．０１〜５質量部程度（更に好ましくは０．０３〜３質量部程度）用いることが好ましい。
【００９１】
剤の種類及びビニル系モノマーを重合するための重合開始剤としては、ベンゾイルパーオキシド、１，１−ジ（ｔ−ブチルパーオキシ）−３，３，５−トリメチルシクロヘキサン、ｎ−ブチル−４，４−ジ（ｔ−ブチルパーオキシ）バレレート、ジクミルパーオキシド、α，α’−ビス（ｔ−ブチルパーオキシジイソプロピル）ベンゼン、ｔ−ブチルパーオキシクメン、ジ−ｔ−ブチルパーオキシドの如き有機過酸化物；アゾビスイソブチロニトリル、ジアゾアミノアゾベンゼンの如きアゾ及びジアゾ化合物が挙げられる。
【００９２】
結着樹脂を合成する方法としては、塊状重合法、溶液重合法、懸濁重合法、乳化重合法が利用できる。
【００９３】
本発明のトナーはＴＨＦ可溶分のＧＰＣによる分子量分布で分子量２，０００〜２５，０００の領域にメインピークを有していることが好ましく、より好ましくは分子量５，０００〜２０，０００の領域にメインピークが存在しているものが良い。さらに、ＴＨＦの可溶分は分子量１０００００以下の成分が５０〜９０％であるトナーが好ましい。メインピークの分子量が２０００未満の場合、トナーとして適度な弾性を持てなくなるため、定着性は向上するもののトナーとしての耐久性が低下する。従って、耐久後半になるに従って、トナー粒子中からの磁性酸化鉄粒子の欠落が生じやすくなり、その結果耐久後半に現像性が低下しやすい。又、メインピークの分子量が２０００未満であるとトナーの保存安定性も低下する。メインピークの分子量が２５，０００より大きい場合、定着性が低下する。
【００９４】
このように、トナーのＴＨＦ可溶分のＧＰＣによる分子量分布において、この様なピークを有するトナーは定着性、耐オフセット及び保存安定性がバランスよく保たれる。
【００９５】
所望の分子量分布を持つトナーを製造するためには、結着樹脂は分子量が２，０００〜２５，０００の領域にメインピークを有していることが好ましい。
【００９６】
分子量分布において、この様なピークを有しない場合、樹脂として適度な弾性を持てなくなるため、トナー製造時の溶融混練時に混練シェアをかけることができず、原材料の分散性が低下し、粉砕工程において、磁性酸化鉄粒子のトナー粒子からの遊離が生じ易くなる。さらに、原材料の分散性が低下することで、定着性及び耐久安定性ともに低下する。
【００９７】
本発明において、トナー及び結着樹脂のＴＨＦ可溶成分のＴＨＦを溶媒としたＧＰＣによる分子量分布は次の条件で測定される。
【００９８】
４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに溶媒としてＴＨＦを毎分１ｍｌの流速で流し、ＴＨＦ試料溶液を約１００μｌ注入して測定する。試料の分子量測定にあたっては試料の有する分子量分布を数種の単分散ポリスチレン標準試料により作成された検量線の体数値とカウント値との関係から算出した。検量線作成用の標準ポリスチレン試料としては例えば、東ソー社製あるいは昭和電工社製の分子量が１０²〜１０⁷程度のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。検出器はＲＩ（屈折率）検出器を用いる。カラムとしては市販のポリスチレンジェルカラムを複数本組み合わせるのが良く、例えば昭和電工社製のｓｈｏｄｅｘ ＧＰＣＫＦ−８０１，８０２，８０３，８０４，８０５，８０６，８０７，８００Ｐの組み合せや、東ソー社製のＴＳＫｇｅｌ Ｇ１０００Ｈ（Ｈ_XL）、Ｇ２０００Ｈ（Ｈ_XL）、Ｇ３０００Ｈ（Ｈ_XL）、Ｇ４０００Ｈ（Ｈ_XL）、Ｇ５０００Ｈ（Ｈ_XL）、Ｇ６０００Ｈ（Ｈ_XL）、Ｇ７０００Ｈ（Ｈ_XL）、ＴＳＫｇｕｒｄ ｃｏｌｕｍｎの組み合せを挙げることができる。
【００９９】
試料は以下のようにして作製する。
【０１００】
試料をＴＨＦ中に入れ、数時間放置した後、十分振とうしＴＨＦとよく混ぜ（試料の合一体が無くなるまで）、更に１２時間以上静置する。その時ＴＨＦ中への放置時間が２４時間以上となるようにする。その後、サンプル処理フィルター（ポアサイズ０．２〜０．５μｍ、例えばマイショリディスクＨ−２５−２（東ソー社製）など使用できる。）を通過させたものをＧＰＣの試料とする。又、試料濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【０１０１】
トナーは、トナーの保存安定性の観点から、ガラス転移温度（Ｔｇ）が４５〜７５℃、好ましくは５０〜７０℃であり、トナーのＴｇが４５℃より低いと高温雰囲気下でトナーが劣化し易く、又、定着時にオフセットが発生し易くなる。又、トナーのＴｇが７５℃を超えると、定着性が低下する傾向にある。
【０１０２】
次に、磁性酸化鉄粒子について説明する。
【０１０３】
本発明に用いられる磁性酸化鉄粒子としては、その表面に鉄あるいは異種元素の酸化物あるいは水酸化物を含有するマグネタイト，マグヘマイト，フェライトの如き磁性酸化鉄及びその混合物が挙げられる。このように、磁性酸化鉄粒子の表面に酸化物あるいは水酸化物を、好ましくは非鉄元素の酸化物あるいは水酸化物を含有することで、結着樹脂に対し馴染みが良く、非常に分散性が良くなるため、トナー粒子の製造時の粉砕工程において遊離磁性酸化鉄粒子を生じにくく、結果として、転写効率が向上し、高湿下及び低湿下で使用しても高い画像品質が安定して得られ、経時において画像欠陥を生じないトナーを得ることができ、また、遊離磁性酸化鉄粒子の帯電コントロールにも貢献している。中でもリチウム，ベリリウム，ボロン，マグネシウム，アルミニウム，シリコン，リン，ゲルマニウム，チタン，ジルコニウム，錫，鉛，亜鉛，カルシウム，バリウム，スカンジウム，バナジウム，クロム，マンガン，コバルト，銅，ニッケル，ガリウム，カドミウム，インジウム，銀，パラジウム，金，水銀，白金，タングステン，モリブデン，ニオブ，オスミウム，ストロンチウム，イットリウム，テクネチウム，ルテニウム，ロジウム，ビスマスから選ばれる少なくとも一つ以上の元素の酸化物あるいは水酸化物を含有する磁性酸化鉄粒子であることが好ましい。
【０１０４】
本発明において、磁性酸化鉄粒子表面の鉄あるいは異種元素の酸化物あるいは水酸化物の存在量は磁性酸化鉄粒子の疎水化度で表すことができ、疎水化度が２０％以下の磁性酸化鉄粒子であれば、上記性能を維持できるだけの鉄あるいは異種元素の酸化物あるいは水酸化物がその表面に存在しているといえる。
【０１０５】
本発明における磁性酸化鉄粒子の疎水化度とは以下の方法によって測定されたものである。
【０１０６】
磁性酸化鉄粒子の疎水化度の測定は、メタノール滴定試験により行った。メタノールを用いた疎水化度測定は次のように行う。磁性酸化鉄粒子０．１ｇを蒸留水５０ｍｌを入れた容量２５０ｍｌのビーカーに添加する。その後メタノールを液中に液底部より１．３ｍｌ／ｍｉｎの速度で供給する。この際、溶液を緩やかに撹拌しながら供給することが好ましい。磁性酸化鉄粒子の沈降終了は、液面に磁性酸化鉄粒子の浮遊物が確認されなくなった時点とし、疎水化度は、沈降終了時点に達した際のメタノール及び水混合液中のメタノールの体積百分率として表される。
【０１０７】
これらの磁性酸化鉄粒子は粒度分布が揃っていると、結着樹脂への分散性が向上し、トナーの帯電性を安定化することができる。また近年はトナー粒径の小径化が進んでおり、重量平均粒径１０μｍ以下のような場合でも、帯電均一性が促進され、トナーの凝集性も軽減され、画像濃度の向上やカブリが改善され、現像性が向上する。特に重量平均粒径６．０μｍ以下のトナーにおいてはその効果は顕著であり、きわめて高精細な画像が得られる。重量平均粒径は５μｍ以上である方が十分な画像濃度が得られて好ましい。
【０１０８】
これらの異種元素の含有率は磁性酸化鉄粒子の鉄元素を基準として０．０５〜１０質量％であることが好ましい。更に好ましくは０．１〜７質量％であり、特に好ましくは０．２〜５質量％、更には０．３〜４質量％である。０．０５質量％より少ないと、これら元素の含有効果が得られなく、良好な分散性や帯電均一性が得られなくなる。また、１０質量％より多くなると、電荷の放出が多くなり帯電不足を生じ、画像濃度が低くなったり、カブリが増加することがある。
【０１０９】
また、これら異種元素の含有分布において、磁性体粒子の表面に近い方に多く存在しているものが好ましい。例えば、磁性酸化鉄粒子の鉄元素溶解率が２０質量％までに存在する異種元素の含有量Ｂと該磁性酸化鉄粒子の異種元素の全含有量Ａとの比（Ｂ／Ａ）×１００が４０％以上であることが好ましい。さらには４０〜８０％が好ましく、６０〜８０％が特に好ましい。表面存在量を多くすることにより分散効果や電気的拡散効果を、より向上させることが出来る。また、トナー粒子中に含有される量としては結着樹脂１００質量部に対して、２０〜２００質量部、特に好ましくは結着樹脂１００質量部に対して４０〜１５０質量部が良い。
【０１１０】
本発明のトナーは、磁性酸化鉄粒子のケイ素元素の含有率が鉄元素を基準にして、０．４〜２．０質量％（より好ましくは、０．５〜０．９質量％）であり、かつ該磁性酸化鉄粒子の最表面におけるＦｅ／Ｓｉの原子比が１．２〜７．０、より好ましくは１．２〜４．０であることが好ましい。
【０１１１】
磁性酸化鉄粒子の最表面におけるＦｅ／Ｓｉの原子比は、Ｘ線光電子分光法（ＸＰＳ）によって測定する。
【０１１２】
ケイ素元素の含有率が０．４質量％より少なくまたはＦｅ／Ｓｉ原子比が７．０を超える場合には、磁性トナーへの改善効果、特に磁性トナーの流動性の改善の程度が低い。ケイ素元素の含有率が２．０質量％より多くまたはＦｅ／Ｓｉ原子比が１．２未満の場合には、環境特性、特に高湿度下における長期放置において、帯電性が低下する。さらには、磁性トナーの耐久性や結着樹脂への磁性酸化鉄粒子の分散性も低下し、粉砕時にトナーからの磁性酸化鉄粒子の遊離を引き起こす原因となる。
【０１１３】
磁性酸化鉄粒子の最表面のケイ素原子量は、磁性酸化鉄粒子の流動性及び吸水性と相関性があり、該磁性酸化鉄粒子を含有した磁性トナーのトナー物性に影響を与える。
【０１１４】
さらに好ましくは、磁性酸化鉄粒子の平滑度が０．３〜０．８、好ましくは０．４５〜０．７、より好ましくは０．５〜０．７を満足することである。平滑度は、磁性酸化鉄粒子の表面の細孔の量に関係し、平滑度が０．３未満の場合、磁性酸化鉄の表面の細孔が多く存在し、水の吸着が促進される。このように、吸着水が脱着しにくい吸着サイトが、より多く存在することで、該磁性酸化鉄粒子を含有する磁性トナーにおいて、特に高湿下の長期放置において帯電特性が低下し、さらには帯電特性の回復が遅くなる。
【０１１５】
さらに好ましくは、該磁性酸化鉄粒子の嵩密度が０．８ｇ／ｃｍ³以上、好ましくは１．０ｇ／ｃｍ³以上を満足することである。
【０１１６】
磁性酸化鉄粒子の嵩密度が０．８ｇ／ｃｍ³未満の場合、トナー製造時における他のトナー材料との物理的混合性が低下し、磁性酸化鉄粒子の分散性が低下し製造時のトナー粒子からの磁性酸化鉄粒子の遊離を引き起こしやすい。
【０１１７】
さらに好ましくは、該磁性酸化鉄粒子のＢＥＴ比表面積が１５．０ｍ²／ｇ以下、好ましくは１２．０ｍ²／ｇ以下を満足することである。磁性酸化鉄粒子のＢＥＴ比表面積が１５．０ｍ²／ｇを超える場合、磁性酸化鉄粒子の水分吸着性が増加し、該磁性酸化鉄粒子を含有した磁性トナーの吸湿性が高くなり帯電性が低下する。
【０１１８】
さらに本発明に使用される磁性酸化鉄粒子は、アルミニウム元素に換算して０．０１〜２．０質量％（より好ましくは、０．０５〜１．０質量％）のアルミニウム水酸化物等のアルミニウム化合物で処理されていることが好ましい。
【０１１９】
理由は明らかではないが、アルミニウム化合物で磁性酸化鉄粒子表面の処理を行うことにより、より磁性トナーの帯電安定化することが可能であることが確認された。
【０１２０】
さらに、本発明に使用される磁性酸化鉄粒子の最表面における、Ｆｅ／Ａｌ原子比が０．３〜１０．０（より好ましくは０．３〜５．０、さらに好ましくは０．３〜２．０）であることが好ましい。磁性酸化鉄粒子の最表面におけるＦｅ／Ａｌ原子比が０．３〜１０．０であると、高湿下においてもトナーの帯電特性を良好に維持できる。
【０１２１】
さらに本発明に使用される磁性酸化鉄粒子は、平均粒径が０．１〜０．４μｍ、好ましくは０．１〜０．３μｍを有していることが好ましい。
【０１２２】
本発明における各種物性データの測定法を以下に詳述する。
【０１２３】
（１）磁性トナーの粒度分布
磁性トナーの粒度分布は種々の方法によって測定できるが、本発明においてはコールターカウンターを用いて行う。測定装置としては、コールターマルチサイザーＩＩＥ（コールター社製）を用いる。電解液は、１級塩化ナトリウムを用いて、約１％ＮａＣｌ水溶液を調製する。例えば、ＩＳＯＴＯＮ（Ｒ）−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定方法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として、界面活性剤（好ましくはアルキルベンゼンスルホン酸塩）を、０．１〜５ｍｌ加え、さらに測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は、超音波分散器で約１〜３分間分散処理を行い、前記測定装置により、アパーチャーとして１００μｍアパーチャーを用いて、トナー粒子の体積、個数を測定して体積分布と個数分布とを算出する。このとき、測定されたデータは粒径１．５９〜６４．０μｍを２５６分割したチャンネルで得られる。その２５６ｃｈで得られたデータを１６分割で処理し、本発明に係るところの体積分布から求めた重量基準の重量平均粒径（Ｄ４）（各チャンネルの中央値をチャンネル毎の代表値とする）、個数分布から求めた個数基準の個数平均粒径（Ｄ１）、及び体積分布から求めた重量基準の粗粉量（１０．１μｍ以上）、個数分布から求めた個数基準の微粉個数（４．００μｍ以下）を求める。
【０１２４】
（２）磁性トナーの個数粒度分布におけるピーク粒度ｘに対する半値幅ｙ
上記磁性トナーの粒度分布で測定したコールターマルチサイザーＩＩＥ（コールター社製）において得られた２５６ｃｈの粒度分布（図２３参照）からピーク粒度ｘの時の頻度％Ａを算出する。
【０１２５】
ピーク粒度ｘにおける頻度％Ａが半値Ａ／２をとる粒度を粒度分布から算出し、ｘ１，ｘ２とする。
【０１２６】
このとき半値幅ｙ＝ｘ２−ｘ１で求めることが出来る。
【０１２７】
コールターカウンターによって２５６ｃｈで測定された個数基準の粒度分布において、ピーク粒度Ｘに対する半値幅Ｙの関係が
２．０６ｘ−９．１１３≦ｙ≦２．０６ｘ−７．３４１ （７）
を満足することがよい。
【０１２８】
コールターカウンターによって２５６ｃｈで測定された個数基準の粒度分布において、ピーク粒度Ｘに対する半値幅Ｙの関係がＹ＞２．０６Ｘ−７．３４１の場合、このトナーはピーク粒度Ｘの累積個数に比べ他の粒度の累積個数が多い、いわゆる粒度分布のブロードなトナーであることを意味する。このようなトナーの場合、トナーの帯電分布にばらつきが生じ現像性、特に耐久性が悪化する。又、コールターカウンターによって２５６ｃｈで測定された個数基準の粒度分布において、ピーク粒度Ｘに対する半値幅Ｙの関係がＹ＜２．０６Ｘ−９．１１３の場合、このトナーは粒度分布が非常にシャープであることを意味する。粒度分布のシャープなトナーを得る場合には分級工程で微粉体と粗粉体を大幅にカットすれば製造することは可能ではあるが、所望の粒度分布をもつトナーの収率が低くなり製造上現実的とはいえない。
【０１２９】
（３）Ｆｅ／Ｓｉ原子比、Ｆｅ／Ａｌ原子比
磁性酸化鉄粒子の最表面におけるＦｅ／Ｓｉ原子比ならびにＦｅ／Ａｌ原子比は、ＸＰＳ測定により求める。その条件は、
ＸＰＳ測定装置：ＶＧ社製ＥＳＣＡＬＡＢ，２００−Ｘ型
Ｘ線光電子分光装置
Ｘ線源：Ｍｇ Ｋα（３００Ｗ）
分析領域：２×３ｍｍ
とする。
【０１３０】
（４）嵩密度
磁性酸化鉄粒子の嵩密度は、ＪＩＳ−Ｋ−５１０１の顔料試験法に準じて測定する。
【０１３１】
（５）平滑度
磁性酸化鉄粒子の平滑度Ｄは次のように求める。
【０１３２】
【数３】

【０１３３】
（６）ＢＥＴ比表面積
磁性酸化鉄粒子のＢＥＴ比表面積の測定は次のようにして行う。
【０１３４】
ＢＥＴ比表面積は、湯浅アイオニクス（株）製、全自動ガス吸着量測定装置：オートソープ１を使用し、吸着ガスに窒素を用い、ＢＥＴ多点法により求める。サンプルの前処理としては、５０℃で１０時間の脱気を行う。
【０１３５】
（７）磁性酸化鉄粒子の平均粒径及び表面積
平均粒径の測定及び磁性酸化鉄粒子の表面積の算出は次のように行う。
【０１３６】
磁性酸化鉄粒子の透過型電子顕微鏡写真を撮影し、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、これを個数平均径で表す。
【０１３７】
表面積の算出には磁性酸化鉄を平均粒径を直径とした球形と仮定し、通常の方法で磁性酸化鉄の密度を測定し表面積の値を求める。
【０１３８】
【数４】

【０１３９】
（８）異種元素量
本発明の磁性酸化鉄粒子中の異種元素量は、蛍光Ｘ線分析装置ＳＹＳＴＥＭ３０８０（理学電機工業（株）製）を使用し、ＪＩＳ Ｋ０１１９「けい光Ｘ線分析通則」に従って、蛍光Ｘ線分析を行うことにより測定する。
【０１４０】
異種元素を有する磁性酸化鉄粒子は、例えば、ケイ素元素である場合は下記方法で製造される。
【０１４１】
第一鉄塩水溶液と、該第一鉄水溶液中のＦｅ²⁺に対し０．９０〜０．９９当量の水酸化アルカリ水溶液とを反応させて得られた水酸化第一鉄コロイドを含む第一鉄塩反応水溶液に、酸素含有ガスを通気することによりマグネタイト粒子を生成させるにあたり、前記水酸化アルカリ水溶液または前記水酸化第一鉄コロイドを含む第一鉄塩のいずれかに、あらかじめ水可溶性ケイ酸塩を鉄元素に対してケイ素元素換算で、全含有量（０．４〜２．０質量％）の５０〜９９％を添加し、８５〜１００℃の温度範囲で加熱しながら、酸素含有ガスを通気して酸化反応することにより、前記水酸化第一鉄コロイドからケイ素元素を含有する磁性酸化鉄粒子を生成させる。その後、酸化反応終了後の懸濁液中に残存するＦｅ²⁺に対して１．００当量以上の水酸化アルカリ水溶液及び残りの水可溶性ケイ酸塩〔全含有量（０．４〜２．０質量％）の１〜５０％〕を添加してさらに８５〜１００℃の温度範囲で加熱しながら、酸化反応してケイ素元素を含有した磁性酸化鉄粒子を生成させる。他の元素の場合は同様な方法で相当する元素の水溶塩を用いることで得られる。
【０１４２】
次いで、アルミニウム水酸化物で処理する場合は、磁性酸化鉄粒子が生成しているアルカリ性懸濁液中に、水可溶性アルミニウム塩を生成粒子に対してアルミニウム元素換算で０．０１〜２．０質量％になるように添加した後、ｐＨを６〜８の範囲に調整して、磁性酸化鉄粒子表面にアルミニウム水酸化物として析出させる。次いでろ過、水洗、乾燥、解砕することにより、本発明に係る磁性酸化鉄粒子を得る。さらに、平滑度、比表面積を好ましい範囲に調整する方法として、ミックスマーラーまたはらいかい機等を用いて圧縮、せん断及びへらなですることが好ましい。
【０１４３】
本発明に使用する磁性酸化鉄粒子に添加するケイ酸化合物は、市販のケイ酸ソーダの如きケイ酸塩類、加水分解で生じるゾル状ケイ酸の如きケイ酸が例示される。
【０１４４】
添加する水可溶性アルミニウム塩としては、硫酸アルミニウムが例示される。
【０１４５】
第一鉄塩としては、一般的に硫酸法チタン製造で副生する硫酸鉄、鋼板の表面洗浄に伴って副生する硫酸鉄の利用が可能である。さらに塩化鉄の使用も可能である。
【０１４６】
磁性トナーに使用し得るその他の着色剤としては、任意の適当な顔料または染料が挙げられる。
【０１４７】
例えば顔料としてカーボンブラック，アニリンブラック，アセチレンブラック，ナフトールイエロー，ハンザイエロー，ローダミンレーキ，アリザリンレーキ，ベンガラ，フタロシアニンブルー，インダンスレンブルーが挙げられる。これらは定着画像の光学濃度を維持するのに充分な量が用いられる。樹脂１００質量部に対し０．１〜２０質量部、好ましくは１〜１０質量部の顔料を使用することが好ましい。同様の目的で、さらに染料が用いられる。例えばアゾ系染料、アントラキノン系染料、キサンテン系染料、メチン系染料があり、樹脂１００質量部に対し０．１〜２０質量部、好ましくは０．３〜１０質量部の染料を使用することが好ましい。
【０１４８】
本発明のトナーに用いられるワックスには次のようなものがある。例えば、低分子量ポリエチレン、低分子量ポリプロピレン、ポリオレフィン共重合物、ポリオレフィンワックス、マイクロクリスタリンワックス、パラフィンワックス、フィッシャートロプシュワックスの如き脂肪族炭化水素系ワックス；酸化ポリエチレンワックスの如き脂肪族炭化水素系ワックスの酸化物；または、それらのブロック共重合物；キャンデリラワックス、カルナバワックス、木ろう、ホホバろうの如き植物系ワックス；みつろう、ラノリン、鯨ろうの如き動物系ワックス；オゾケライト、セレシン、ペトロラクタムの如き鉱物系ワックス；モンタン酸エステルワックス、カスターワックスの如き脂肪酸エステルを主成分とするワックス類；脱酸カルナバワックスの如き脂肪酸エステルを一部又は全部脱酸化したものが挙げられる。さらに、パルミチン酸、ステアリン酸、モンタン酸、あるいは更に長鎖のアルキル基を有する長鎖アルキルカルボン酸の如き飽和直鎖；ブラシジン酸、エレオステアリン酸、バリナリン酸の如き不飽和脂肪酸；ステアリルアルコール、エイコシルアルコール、ベヘニルアルコール、カルナウビルアルコール、セリルアルコール、メリシルアルコール、あるいは更に長鎖のアルキル基を有する長鎖アルキルアルコールの如き飽和アルコール；ソルビトールの如き多価アルコール；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドの如き脂肪族アミド；メチレンビスステアリン酸アミド、エチレンビスカプリン酸アミド、エチレンビスラウリン酸アミド、ヘキサメチレンビスステアリン酸アミドの如き飽和脂肪酸ビスアミド；エチレンビスオレイン酸アミド、ヘキサメチレンビスオレイン酸アミド、Ｎ，Ｎ’−ジオレイルアジピン酸アミド、Ｎ，Ｎ’−ジオレイルセバシン酸アミドの如き不飽和脂肪酸アミド類；ｍ−キシレンビスステアリン酸アミド、Ｎ，Ｎ’−ジステアリルイソフタル酸アミドの如き芳香族系ビスアミド；ステアリン酸カルシウム、ラウリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムの如き脂肪酸金属塩（一般に金属石けんといわれているもの）；脂肪族炭化水素系ワックスにスチレンやアクリル酸の如きビニル系モノマーを用いてグラフト化させたワックス；ベヘニン酸モノグリセリドの如き脂肪酸と多価アルコールの部分エステル化物；植物性油脂を水素添加することによって得られるヒドロキシル基を有するメチルエステル化合物が挙げられる。
【０１４９】
好ましく用いられるワックスとしては、オレフィンを高圧下でラジカル重合したポリオレフィン；高分子量ポリオレフィン重合時に得られる低分子量副生成物を精製したポリオレフィン；低圧下でチーグラー触媒、メタロセン触媒の如き触媒を用いて重合したポリオレフィン；放射線、電磁波又は光を利用して重合したポリオレフィン；高分子ポリオレフィンを熱分解して得られる低分子量ポリオレフィン；パラフィンワックス、マイクロクリスタリンワックス、フィッシャートロプシュワックス；ジンドール法、ヒドロコール法、アーゲ法等により合成される合成炭化水素ワックス；炭素数１個の化合物をモノマーとする合成ワックス、水酸基又はカルボキシル基の如き官能基を有する炭化水素系ワックス；炭化水素系ワックスと官能基を有するワックスとの混合物；これらのワックスを母体としてスチレン、マレイン酸エステル、アクリレート、メタクリレート、無水マレイン酸の如きビニルモノマーをグラフト変性したワックスが挙げられる。
【０１５０】
また、これらのワックスをプレス発汗法、溶剤法、再結晶法、真空蒸留法、超臨界ガス抽出法又は融液晶法を用いて分子量分布をシャープにしたものや、低分子量固形脂肪酸、低分子量固形アルコール、低分子量固形化合物、その他の不純物を除去したものも好ましく用いられる。
【０１５１】
本発明に使用するワックスは、定着性と耐オフセット性のバランスを取るために融点が６５〜１６０℃であることが好ましく、更には６５〜１３０℃であることが好ましく、特には７０℃〜１２０℃であることが好ましい。６５℃未満では耐ブロッキング性が低下し、１６０℃を超えると耐オフセット効果が発現し難くなる。
【０１５２】
本発明のトナーにおいては、これらのワックス総含有量は、結着樹脂１００質量部に対し、０．２〜２０質量部で用いられ、好ましくは０．５〜１０質量部で用いるのが効果的である。また、悪影響を与えない限り他のワックス類と併用しても構わない。
【０１５３】
ワックスの融点は、ＤＳＣにおいて測定されるワックスの吸熱ピークの最大ピークのピークトップの温度をもってワックスの融点とする。
【０１５４】
本発明において、ワックス又はトナーの示差走査熱量計によるＤＳＣ測定では例えば、パーキンエルマー社製のＤＳＣ−７が利用できる。
【０１５５】
測定方法は、ＡＳＴＭ Ｄ３４１８−８２に準じて行う。本発明に用いられるＤＳＣ曲線は、１回昇温させ前履歴を取った後、温度測定１０℃／ｍｉｎ、温度０〜２００℃の範囲で降温させた後、昇温させた時に測定されるＤＳＣ曲線を用いる。
【０１５６】
本発明のトナーは、荷電制御剤を添加して使用することが好ましい。
【０１５７】
負荷電制御剤としては、特公昭４１−２０１５３号公報、特公昭４２−２７５９６号公報，特公昭４４−６３９７号公報，特公昭４５−２６４７８号公報に記載されているモノアゾ染料の金属錯体；さらには特開昭５０−１３３８３８号公報に記載されているニトロフミン酸及びその塩或いはＣ．Ｉ．１４６４５の如き染顔料；特公昭５５−４２７５２号公報，特公昭５８−４１５０８号公報，特公昭５８−７３８４号公報，特公昭５９−７３８５号公報に記載されているサリチル酸、ナフトエ酸、ダイカルボン酸のＺｎ，Ａｌ，Ｃｏ，Ｃｒ，Ｆｅ又はＺｒの金属錯体；スルホン化した銅フタロシアニン顔料；ニトロ基，ハロゲンを導入したスチレンオリゴマー；塩素化パラフィンを挙げることができる。特に分散性に優れ、画像濃度の安定性やカブリの低減に効果のある、一般式（Ｉ）で表されるアゾ系金属錯体や一般式（ＩＩ）で表される塩基性有機酸金属錯体が好ましい。
【０１５８】
【化５】

【０１５９】
【化６】

【０１６０】
そのうち上記式（Ｉ）で表されるアゾ系金属錯体がより好ましく、とりわけ、中心金属がＦｅである下記式（ＩＩＩ）あるいは（ＩＶ）で表されるアゾ系鉄錯体が最も好ましい。
【０１６１】
【化７】

【０１６２】
【化８】

【０１６３】
次に、上記式（ＩＩＩ）で示されるアゾ系鉄錯体の具体例を下記に示す。
【０１６４】
【化９】

【０１６５】
【化１０】

【０１６６】
【化１１】

【０１６７】
また、上記式（Ｉ），（ＩＩ），（ＩＶ）で示される荷電制御剤の具体例を以下に示す。
【０１６８】
【化１２】

【０１６９】
【化１３】

【０１７０】
【化１４】

【０１７１】
これらの金属錯化合物は、単独でも或いは２種以上組み合わせて用いることが可能である。
【０１７２】
これらの帯電制御剤の使用量は、トナーの帯電量の点から結着樹脂１００質量部あたり０．１〜５．０質量部が好ましい。
【０１７３】
一方、トナーを正荷電性に制御するものとして下記物質がある。
【０１７４】
ニグロシン及び脂肪酸金属塩によるニグロシンの変性物；トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートの如き四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩のオニウム塩及びこれらのレーキ顔料；トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）；高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドの如きジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートの如きジオルガノスズボレート類。これらを単独で或いは２種類以上組合せて用いることができる。
【０１７５】
また、本発明のトナーには、トナー粒子に無機微粉体または疎水性無機微粉体が外添されることが好ましい。例えば、シリカ微粉末を添加して用いることが好ましい。
【０１７６】
本発明に用いられるシリカ微粉体は、ケイ素ハロゲン化合物の蒸気相酸化により生成された乾式法またはヒュームドシリカと称される乾式シリカ及び水ガラスから製造される湿式シリカの両方が使用可能である。表面及び内部にあるシラノール基が少なく、製造残渣のない乾式シリカの方が好ましい。
【０１７７】
さらに本発明に用いるシリカ微粉体は疎水化処理されているものが好ましい。疎水化処理するには、シリカ微粉体と反応あるいは物理吸着する有機ケイ素化合物で化学的に処理することによって付与される。好ましい方法としては、ケイ素ハロゲン化合物の蒸気相酸化により生成された乾式シリカ微粉体をシランカップリング剤で処理した後、あるいはシランカップリング剤で処理すると同時にシリコーンオイルの如き有機ケイ素化合物で処理する方法が挙げられる。
【０１７８】
疎水化処理に使用されるシランカップリング剤としては、ヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシランメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサンが挙げられる。
【０１７９】
有機ケイ素化合物としては、シリコーンオイルが挙げられる。好ましいシリコーンオイルとしては、２５℃における粘度がおよそ３×１０^-5〜１×１０^-3ｍ²／ｓのものが用いられる。ジメチルシリコーンオイル、メチルフェニルシリコーンオイル、α−メチルスチレン変性シリコーンオイル、クロルフェニルシリコーンオイル、フッ素変性シリコーンオイルが好ましい。
【０１８０】
シリコーンオイル処理の方法はシランカップリング剤で処理されたシリカ微粉体とシリコーンオイルとをヘンシェルミキサーの如き混合機を用いて直接混合しても良いし、べースとなるシリカへシリコーンオイルを噴射する方法によっても良い。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、べースのシリカ微粉体とを混合し、溶剤を除去して作製しても良い。
【０１８１】
本発明のトナーには、必要に応じてシリカ微粉体以外の外添剤を使用しても良い。
【０１８２】
例えば帯電補助剤、導電性付与剤、流動性付与剤、ケーキング防止剤、熱ロール定着時の離型剤、滑剤又は研磨剤の働きをする樹脂微粒子や無機微粒子である。
【０１８３】
例えば弗素樹脂，ステアリン酸亜鉛，ポリ弗化ビニリデンの如き滑剤、中でもポリ弗化ビニリデンが好ましい。酸化セリウム，炭化ケイ素，チタン酸ストロンチウムの如き研磨剤、中でもチタン酸ストロンチウムが好ましい。酸化チタン，酸化アルミニウムの如き流動性付与剤、中でも特に疎水性のものが好ましい。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。トナー粒子と摩擦帯性が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ることもできる。
【０１８４】
トナーと混合される無機微粉体または疎水性無機微粉体は、トナー１００質量部に対して０．１〜５質量部（好ましくは０．１〜３質量部）使用するのが良い。
【０１８５】
さらに本発明の磁性トナーはＣａｒｒの噴流性指数が８０より大きい値であることが好ましく、より好ましくはＣａｒｒの流動性指数が６０より大きい値である。
【０１８６】
さらに、本発明の磁性トナーはＣａｒｒの噴流性指数が８１〜８９であるのがより好ましい。さらに、本発明の磁性トナーはＣａｒｒの流動性指数が６１〜７９であるのがより好ましい。
【０１８７】
磁性トナーの流動性指数及び噴流性指数については、以下の方法で測定する。パウダテスタＰ−１００（ホソカワミクロン社製）を使用し、安息角、崩潰角、差角、圧縮度、凝集度、スパチュラ角、分散度の各パラメーターを測定する。それぞれについて求められた値をＣａｒｒの流動性指数表，噴流性指数表に当てはめ、各２５以下のそれぞれの指数に換算し、各パラメーターから求められた指数の合計を流動性指数・噴流性指数として算出した。以下に各パラメーターの測定方法を示す。
【０１８８】
▲１▼安息角
トナー１５０ｇを目開き７１０μｍのメッシュを通して直径８ｃｍの円形テーブルの上にトナーを堆積させる。このとき、テーブルの端部からトナーがあふれる程度に堆積させる。このときのテーブル上に堆積したトナーの稜線と円形テーブル面との間に形成された角度をレーザー光で測定することで安息角とした。
【０１８９】
▲２▼圧縮度
疎充填かさ密度（緩み見かけ比重Ａ）と、タッピングかさ密度（固め見かけ比重Ｐ）から圧縮度を求めることができる。
圧縮度（％）＝１００（Ｐ−Ａ）／Ｐ
○緩み見かけ比重測定法 直径５ｃｍ、高さ５．２ｃｍ、容量１００ｃｃのカップにトナー１５０ｇを静かに流し込む。測定用カップにトナーが山盛りに充填されたところで、トナー表面をすりきり、カップに充填されているトナーの量から、緩み見かけ比重を算出する。
○固め見かけ比重測定法 緩み見かけ比重で使用した測定用カップに、付属のキャップを継ぎ足す。トナーをカップに充填し、カップを１８０回タップさせる。タッピングが終了した時点でキャップを外し、カップに山盛りになっている余分なトナーをすりきる。カップに充填されているトナーの量から固め見かけ比重を算出する。
両見かけ比重値を圧縮度の式に挿入し、圧縮度を求める。
【０１９０】
▲３▼スパチュラ角
１０ｃｍ×１５ｃｍのバットの底が３ｃｍ×８ｃｍのスパチュラに接するように置く。スパチュラの上にトナーを堆積させる。このとき、トナーがスパチュラの上に盛り上がるように堆積させる。その後、バットだけを静かに下ろし、スパチュラ上に残ったトナー側面の傾斜角をレーザー光により測定する。
【０１９１】
その後、スパチュラに取り付けたショッカーで一回衝撃を加えた後、再度スパチュラ角を測定する。この測定値と衝撃を与える前の測定値の平均をスパチュラ角として算出した。
【０１９２】
▲４▼凝集度
振動台の上に、上から目開き２５０μｍ、１５０μｍ、７５μｍの順でふるいをセットする。振動振り巾を１ｍｍ、振動時間を２０秒とし、トナー５ｇを静かにのせて振動させる。振動停止後、それぞれのふるいに残った重量を測定する。
（上段のふるいに残ったトナー量）÷５（ｇ）×１００・・・ａ
（中段のふるいに残ったトナー量）÷５（ｇ）×１００×０．６・・・ｂ
（下段のふるいに残ったトナー量）÷５（ｇ）×１００×０．２・・・ｃ
ａ＋ｂ＋ｃ＝凝集度（％）として算出する。
【０１９３】
パラメーターから求められた値をＣａｒｒの流動性指数、噴流性指数の表（Ｃｈｅｍｉｃａｌ Ｅｎｇｉｎｅｅｒｉｎｇ．Ｊａｎ．１８．１９６５）により２５以下の指数に換算し、それらの値の合計▲１▼＋▲２▼＋▲３▼＋▲４▼＝Ｃａｒｒの流動性指数となる。
【０１９４】
▲５▼崩潰角
安息角測定後、測定用円形テーブルを乗せているバットにショッカーで３回衝撃を加える。その後、テーブルに残ったトナーの角度をレーザー光を用いて想定し、崩潰角とする。
【０１９５】
▲６▼差角
安息角と崩潰角の差が差角となる。
【０１９６】
▲７▼分散度
トナー１０ｇを約６０センチの高さから直径１０ｃｍのウォッチグラス上に一塊として落とす。そして、ウォッチグラス上に残ったトナーを測り、次の式により分散度を求める。
分散度（％）＝（（１０−（皿上に残ったトナー量））×１０
【０１９７】
▲５▼、▲６▼、▲７▼の値から換算できる指数を、上記で求めた流動性指数値が対応する指数との合計を前述のＣａｒｒの表により噴流性指数として求めることができる。
【０１９８】
上記の測定を行った結果、噴流性指数が８０よりも大きな値（さらに好ましくは、８１〜８９）、より好ましくはＣａｒｒの流動性指数が６０より大きい値（さらに好ましくは、６１〜７９）を示すような磁性トナーであれば、カートリッジ内に高い充填率で磁性トナーが充填されても、撹拌部材で撹拌時に、高い流動性が再現されるため、カートリッジ内のトナー収容部から現像スリーブへ向かって磁性トナーが一定に搬送されやすく、高速化したプリンターや大容量のカートリッジに充填した場合においても安定した現像特性を得ることが出来る。本発明の磁性トナーにおいては、磁性トナー粒子の粒径や形状、外添剤の量や付着状態を変化させることで適正な噴流性指数、流動性指数を達成することが可能となる。前述したように磁性トナー中において、遊離した鉄元素を有する粒子を該トナー粒子１０，０００個当たり１００〜３５０個にコントロールすることによって、遊離した磁性酸化鉄粒子の凝集に起因する流動性の低下を抑えることが出来、さらに、外添時に使用する撹拌羽の形状や混合装置への充填量、撹拌モードを変えて撹拌状態を変えることにより、上記の噴流性指数、流動性指数を達成することができる。
【０１９９】
磁性トナーの噴流性指数が８０以下の場合、高い流動性は得られても、一度詰まってしまうと力を加えてもなかなか流動しにくいため、撹拌部材で磁性トナーを搬送しようとしても、なかなか搬送されない。その結果、磁性トナーが現像スリーブまで搬送されにくく、現像スリーブ上に不均一に磁性トナーがのった状態で帯電されるため、磁性トナーの帯電も不均一になりやすく画像にムラが生じ易い。
【０２００】
また、磁性トナーの噴流性指数が８０以下で、トナーの流動性指数が６０以下の場合、磁性トナー同志が凝集しやすく、また流動しにくいためカートリッジ内の摺動部への磁性トナーの融着が生じやすい。
【０２０１】
さらに本発明の磁性トナーは鉄粉キャリアに対する摩擦帯電量の絶対値の値を│Ｑｄ│としたとき、
７０≧│Ｑｄ│≧２０μＣ／ｇ
であることが好ましい。摩擦帯電量の値は磁性トナーの表面形状、磁性トナー粒子表面への磁性酸化鉄粒子の露出状態によって大きく変化することから、本発明において所望の摩擦帯電量を得るためには前述したように円形度、トナー粒子からの磁性酸化鉄粒子の遊離率をコントロールするとともに外添剤の種類や量を変化させ、さらに、外添時に使用する撹拌羽の形状や混合装置への充填量、撹拌モードを変えて撹拌状態を変えることが重要となる。
【０２０２】
Ｑｄの測定法を以下に示す。
【０２０３】
測定には図１９に示す帯電量測定装置を用いる。温度２３℃，相対湿度６０％環境下、鉄粉キャリアとして粒径１０６〜１５０μｍの範囲に５０〜７０質量％、粒径７５〜１０６μｍの範囲に２０〜５０質量％の分布を持つような鉄粉キャリア（例えばＤＳＰ１３８（同和鉄粉社製））を用い、鉄粉キャリア９．０ｇに磁性トナー１．０ｇを加えた混合物を５０〜１００ｍｌ容量のポリエチレン製の瓶に入れ５０回手で振盪する。
【０２０４】
次いで、底に５００メッシュのスクリーン９０３のある金属製の測定容器９０２に前記混合物１．０〜１．２ｇを入れ、金属製のフタ９０４をする。この時の測定容器９０２全体の重量を秤りＷ１（ｇ）とする。次に吸引機９０１（測定容器９０２と接する部分は少なくとも絶縁体）において、吸引口９０７から吸引し風量調節弁９０６を調節して真空計９０５の圧力を２ｋＰａとする。
【０２０５】
この状態で１分間吸引を行ない、現像剤を吸引除去する。この時の電位計９０９の電位をＶ（ボルト）とする。ここで８はコンデンサーであり容量をＣ（μＦ）とする。また、吸引後の測定機全体の重量を秤りＷ２（ｇ）とする。磁性トナーの摩擦帯電量Ｑｄ（μＣ／ｇ）は下式の如く計算される。
Ｑｄ＝ＣＶ／（Ｗ１−Ｗ２）
【０２０６】
鉄粉キャリアに対する磁性トナーの摩擦帯電量の絶対値が７０μＣ／ｇ≦│Ｑｄ│の場合、特に低湿下においてチャージアップによる現像性の低下が見られる。│Ｑｄ│≦２０μＣ／ｇの場合、帯電量の低さが原因となり現像剤担持体上の磁性トナーの適切な静電的凝集力と現像剤担持体への適切な磁気拘束力が得られず、磁性トナーが静電潜像へ忠実に移行できなくなり現像性の低下が見られる。
【０２０７】
また、本発明の磁性トナーは、トナーの示差走査熱量計により測定されるＤＳＣ曲線の最大吸熱ピークが６０〜１２０℃に有することが好ましい。最大吸熱ピークが６０℃未満である場合、耐オフセット性及び耐ブロッキング性が低下する。最大吸熱ピークが１２０℃を超える場合には定着性が低下する。
【０２０８】
さらに、本発明のトナーは示差走査熱量計により測定されるＤＳＣ曲線の最大吸熱ピークが６０〜１２０℃であり、サブ吸熱ピークが６０〜１６０℃にあり、それぞれの吸熱ピークの間が２０℃以上離れていることがより好ましい。
【０２０９】
それぞれの吸熱ピークの差が２０℃未満の場合、定着性と離型性の機能分離効果が発現しにくくなる。このように上記のような吸熱ピークが存在することで磁性トナーを可塑化する効果と離型作用を与える効果が程よく調整出来、定着性と耐オフセット性、耐ブロッキング性をバランス良く両立できるようになる。更に、本発明の円形度を有することで可塑効果をより効果的に発揮でき、幅広い温度領域で離型作用を発揮できる。
【０２１０】
以下、本発明のトナーの好ましい製造方法の実施の形態を添付図面を参照しながら具体的に説明する。図１は、本発明のトナーの製造方法の概要を示すフローチャートの一例である。本発明の製造方法は、フローチャートに示されている様に、粉砕処理前の分級工程を必要とせず、粉砕工程及び分級工程が１パスで行われることが好ましい。
【０２１１】
トナーの製造方法においては、特定のトナー構成材料を用い、製造条件を種々選択しトナーを製造することで、遊離磁性酸化鉄の個数やトナーの円形度を制御することが可能となる。一般には、結着樹脂、着色剤及びワックスを少なくとも含有する混合物を溶融混練し、得られた混練物を冷却した後、冷却物を粉砕手段によって粉砕して得られた粗粉砕物が粉体原料として使用される。そして、所定量の粉砕原料を少なくとも中心回転軸に取り付けられた回転体からなる回転子と、該回転子表面と一定間隔を保持して回転子の周囲に配置されている固定子とを有し、且つ該間隔を保持することによって形成される環状空間が気密状態となるように構成されている機械式粉砕機に導入し、該機械式粉砕機の上記回転子を高速回転させることによって被粉砕物を微粉砕する。次に、微粉砕された粉砕原料は分級工程に導入され分級されて、好ましい粒度を有する粒子群からなるトナー粒子が得られる。この際、分級工程では、少なくとも粗粉領域、中粉領域及び微粉領域を有する多分割気流式分級機が好ましく用いられる。例えば、３分割気流式分級機を使用した場合には、粉体原料は少なくとも微粉体、中粉体及び粗粉体の３種類に分級される。このような分級機を用いる分級工程で、好ましい粒度よりも粒径の大きな粒子群からなる粗粉体及び好ましい粒度未満の粒子群からなる超微粉体は除かれ、中粉体がトナー粒子としてそのままトナーとして使用されるか、又は、疎水性コロイダルシリカの如き外添剤と混合された後、トナーとして使用される。
【０２１２】
上記の分級工程で分級された好ましい粒度未満の粒子群からなる超微粉は、一般的には、粉砕工程に導入されてくるトナー材料からなる粉体原料を生成する為の溶融混練工程に供給されて再利用されるか、或いは廃棄される。
【０２１３】
図２にトナーの製造装置システムの一例を示す。この装置システムに導入されるトナー原料である粉体原料には結着樹脂、着色剤及びワックスを少なくとも含有する着色樹脂粒子粉体が用いられるが、該粉体原料は、例えば、結着樹脂、磁性酸化鉄及びワックスからなる混合物を溶融混練し、得られた混練物を冷却し、更に冷却物を粉砕手段によって粗粉砕したものが用いられる。
【０２１４】
この装置システムにおいて、トナー粉原料となる粉砕原料は、粉砕手段である機械式粉砕機３０１に第１定量供給機３１５を介して所定量導入される。導入された粉砕原料は、機械式粉砕機３０１で瞬間的に粉砕され、補集サイクロン２２９を介して第２定量供給機２に導入される。次いで振動フィーダー３を介し、更に原料供給ノズル１６を介して分級手段である多分割気流式分級機１内に供給される。
【０２１５】
また、この装置システムにおいて、第１定量供給機３１５から粉砕手段である機械式粉砕機３０１に導入される所定量と、第２定量供給機２から分級手段である多分割気流式分級機１に導入される所定量との関係を、第１定量供給機３１５から機械式粉砕機３０１に導入される所定量を１とした場合、第２定量供給機２から多分割気流式分級機１に導入される所定量を好ましくは０．７〜１．７、より好ましくは０．７〜１．５、更に好ましくは１．０〜１．２とすることがトナーの生産性及び生産効率という点から好ましい。
【０２１６】
通常、本発明の気流式分級機は、相互の機器をパイプの如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２は示している。図２に示す一体装置システムは、多分割分級装置１（図６に示される分級装置）、定量供給機２、振動フィーダー３、補集サイクロン４、補集サイクロン５、補集サイクロン６を連通手段で連結してなるものである。
【０２１７】
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２に送り込まれ、次いで振動フィーダー３を介し、原料供給ノズル１６により３分割分級装置１内に導入される。導入に際しては、１０〜３５０ｍ／秒の流速で３分割分級機１内に粉体を導入する。３分割分級機１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種類以上の粒子群に分級し得る。そして、３分割分級機１により、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を逝って、補集サイクロン６に送られ機械式粉砕機３０１に戻される。中間の粒子は排出導管１２ａを介して系外に排出され補集サイクロン５で補集されトナーとなるべく回収される。小さい粒子は排出導管１３ａを介して系外に排出され補集サイクロン４で補集され、トナー材料からなる粉体原料を生成する為の溶融混練工程に供給されて再利用されるか、或いは廃棄される。補集サイクロン４、５、６は粉体を原料供給ノズル１６を介して分級室に吸引導入する為の吸引減圧手段としての働きをすることも可能である。また、この際分級される大きい粒子は、第１定量供給機３１５に再導入し、粉体原料中に混入させて、機械式粉砕機３０１にて再度粉砕することが好ましい。
【０２１８】
また、多分割気流式分級機１から機械式粉砕機３０１に再導入される大きい粒子（粗粒子）の再導入量は、第２定量供給機２から供給される微粉砕品の質量を基準として、０乃至１０．０質量％、更には０乃至５．０質量％とすることがトナー生産上好ましい。多分割気流式分級機１から機械式粉砕機３０１に再導入される大きい粒子（粗粒子）の再導入量が１０．０質量％を超えると、機械式粉砕機３０１内の粉塵濃度が増大し、装置自体の負荷が大きくなるのと同時に、粉砕時に過粉砕され熱によるトナーの表面変質や磁性酸化鉄のトナー粒子からの遊離、機内融着を起こしやすいのでトナー生産性という点から好ましくない。
【０２１９】
この装置システムにおいて、粉体原料の粒度は、１８メッシュパス（ＡＳＴＭＥ−１１−６１）が９５質量％以上であり、１００メッシュオン（ＡＳＴＭＥ−１１−６１）が９０質量％以上であることが好ましい。
【０２２０】
また、この装置システムにおいて、重量平均粒径が１０μｍ以下（更には８μｍ以下）のシャープな粒度分布を有するトナーを得る為には、機械式粉砕機で微粉砕された微粉砕物の重量平均粒径が５乃至１０μｍ、４．０μｍ以下が７０個数％以下、更には６５個数％以下、１０．１μｍ以上が２５体積％以下、更には２０体積％以下であることが好ましい。また、分級された中粉体の粒度は、重量平均粒径が５乃至１０μｍ、４．０μｍ以下が４０個数％以下、更には３５個数％以下、１０．１μｍ以上が２５体積％以下、更には２０体積％以下であることが好ましい。
【０２２１】
本発明のトナーの製造方法を適用した上記装置システムにおいては、粉砕処理前の第１分級工程を必要とせず、粉砕工程及び分級工程を１パスで行うことができる。
【０２２２】
本発明のトナーの製造方法に使用される粉砕手段として好ましく用いられる機械式粉砕機について説明する。機械式粉砕機としては、例えば、川崎重工業（株）製粉砕機ＫＴＭ、ターボ工業（株）製ターボミルを挙げることができる。これらの装置をそのまま、或いは適宜改良して使用することが好ましい。
【０２２３】
これらの中でも図３、図４及び図５に示したような機械式粉砕機を用い、トナー構成材料として特定の原材料を使用してトナーを製造することが、トナー粒子の形状と遊離磁性酸化鉄粒子の個数をコントロールして製造できる方法として好ましい。さらに、粉体原料の粉砕処理を容易に行うことができるので効率向上が図られ好ましい。
【０２２４】
従来行われていた衝突式気流粉砕では、衝突部材の衝突面にトナー粒子を衝突させ、その衝撃によって粉砕するという構成のため、衝突時に遊離磁性酸化鉄粒子が発生しやすい。さらに粉砕されたトナーは、不定形で角張ったものとなるため、トナー粒子からの磁性酸化鉄粒子の脱落が生じやすい。また、衝突式気流粉砕で製造されたトナー粒子を機械式衝撃（ハイブリタイザー）により粒子の形状及び表面性を改質することも可能ではあるが、衝突式粉砕では衝突部材の衝突面にトナー粒子を衝突させ、その衝撃によって粉砕するという構成のため、衝突時に遊離磁性酸化鉄粒子が発生しやすい。その後、機械式衝撃で粒子の形状を改質させ形状を球形に近づけることにより不定形のトナーに比ベトナーからの磁性酸化鉄粒子の脱落が生じにくくはなるものの、機械式粉砕機を用いたトナーの製造方法に比べ、トナーの形状と遊離磁性酸化鉄粒子の個数をコントロールすることは困難である。
【０２２５】
以下、図３、図４及び図５に示した機械式粉砕機について説明する。図３は、機械式粉砕機の一例の概略断面図を示しており、図４は図３におけるＤ−Ｄ’面での概略的断面図を示しており、図５は図３に示す回転子３１４の斜視図を示している。該装置は、図３に示されているように、ケーシング３１３、ジャケット３１６、ディストリビュータ２２０、ケーシング３１３内にあって中心回転軸３１２に取り付けられた回転体からなる高速回転する表面に多数の溝が設けられている回転子３１４、回転子３１４の外周に一定間隔を保持して配置されている表面に多数の溝が設けられている固定子３１０、更に、被処理原料を導入する為の原料投入口３１１、処理後の粉体を排出する為の原料排出口３０２とから構成されている。
【０２２６】
機械式粉砕機での粉砕操作は、例えば次の様にして行う。即ち、図３に示した機械式粉砕機の粉体入口３１１から、所定量の粉体原料が投入されると、粒子は、粉砕処理室内に導入され、該粉砕処理室内で高速回転する表面に多数の溝が設けられている回転子３１４と、表面に多数の溝が設けられている固定子３１０との間に発生する衝撃と、この背後に生じる多数の超高速渦流、並びにこれによって発生する高周波の圧力振動によって瞬時に粉砕される。その後、原料排出口３０２を通り、排出される。トナー粒子を搬送しているエアー（空気）は粉砕処理室を経由し、原料排出口３０２、パイプ２１９、補集サイクロン２２９、バグフィルター２２２、及び吸引フィルター２２４を通って装置システムの系外に排出される。本発明においては、粉体原料の粉砕が行われる為、微粉及び粗粉を増やすことなく所望の粉砕処理を容易に行うことができる。
【０２２７】
また、粉砕原料を機械式粉砕機で粉砕する際に、冷風発生手段３２１により、粉体原料と共に、機械式粉砕機内に冷風を送風し、機械式粉砕機本体をジャケット構造３１６を有する構造とし、冷却水（好ましくはエチレングリコールの如き不凍液）を通水することにより、粉砕機内の雰囲気温度を０℃以下、より好ましくは−５〜−１５℃、更に好ましくは−７〜−１２℃とすることがトナー生産性という点から好ましい。粉砕機内の渦巻室の室温を０℃以下、より好ましくは−５〜−１５℃、更に好ましくは−７〜−１２℃とすることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。粉砕機内の雰囲気温度が０℃を超える場合、粉砕時に熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離や機内融着を起こしやすいのでトナー生産性という点から好ましくない。また、粉砕機内の雰囲気温度を−１５℃より低い温度で運転しようとすると、上記冷風発生手段３２１で使用している冷媒（代替フロン）をフロンに変更しなければならない。
【０２２８】
現在、オゾン層保護の観点からフロンの撤廃が進められている。上記冷風発生手段３２１の冷媒にフロンを使用することは地球全体の環境問題という点から好ましくない。
【０２２９】
冷却水（好ましくはエチレングリコールの如き不凍液）は、冷却水供給口３１７よりジャケット内部に供給され、冷却水排出口３１８より排出される。
【０２３０】
また、粉砕原料を機械式粉砕機で粉砕する際に、機械式粉砕機の渦巻室２１２の室温Ｔ１と後室３２１の室温Ｔ２の温度差ΔＴ（Ｔ２−Ｔ１）を３０〜８０℃とすることが好ましく、より好ましくは３５〜７５℃、更に好ましくは３７〜７２℃とすることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。機械式粉砕機の温度Ｔ１（入口温度）と温度Ｔ２（出口温度）とのΔＴが３０℃より小さい場合、粉砕されずにショートパスを起こしている可能性があり、トナーの性能という点から好ましくない。また、８０℃より大きい場合、粉砕時に過粉砕されている可能性があり、それによる磁性酸化鉄粒子の遊離や熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離や機内融着を起こしやすいのでトナー生産性という点から好ましくない。
【０２３１】
また、粉砕原料を機械式粉砕機で粉砕する際に機械式粉砕機の入口温度は、結着樹脂のガラス転移点（Ｔｇ）に対して、０℃以下であり且つＴｇよりも６０乃至７５℃低くすることがトナー生産性という点から好ましい。機械式粉砕機の入口温度を０℃以下であり且つＴｇよりも６０乃至７５℃低くすることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。また、出口温度は、Ｔｇよりも５乃至３０℃、更には１０乃至２０℃低いことが好ましい。機械式粉砕機の出口温度をＴｇよりも５乃至３０℃低くすることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。
【０２３２】
また、回転する回転子３１４の先端周速としては、８０〜１８０ｍ／ｓであることが好ましく、より好ましくは９０〜１７０ｍ／ｓ、更に好ましくは１００〜１６０ｍ／ｓとすることがトナー生産性という点から好ましい。回転する回転子３１４の周速を８０〜１８０ｍ／ｓであることが好ましく、より好ましくは９０〜１７０ｍ／ｓ、更に好ましくは１００〜１６０ｍ／ｓとすることで、トナー粒子の粉砕不足や過粉砕、さらに過粉砕による磁性酸化鉄粒子の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。回転子の周速が８０ｍ／ｓより遅い場合、粉砕されずにショートパスを起こしやすいのでトナー性能という点から好ましくない。また、回転子３１４の周速が１８０ｍ／ｓより速い場合、装置自体の負荷が大きくなるのと同時に、粉砕時に過粉砕されて磁性酸化鉄粒子が遊離しやすい。さらに、過粉砕されることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離や機内融着を起こしやすいのでトナー生産性という点から好ましくない。
【０２３３】
また、回転子３１４と固定子３１０との間の最小間隔は０．５〜１０．０ｍｍであることが好ましく、より好ましくは１．０〜５．０ｍｍ、更に好ましくは１．０〜３．０ｍｍとすることが好ましい。回転子３１４と固定子３１０との間の間隔を０．５〜１０．０ｍｍであることが好ましく、より好ましくは１．０〜５．０ｍｍ、更に好ましくは１．０〜３．０ｍｍとすることで、トナーの粉砕不足や過粉砕、さらに過粉砕による磁性酸化鉄粒子の遊離を抑えることができ、効率良く粉砕原料を粉砕することができる。回転子３１４と固定子３１０との間の間隔が１０．０ｍｍより大きい場合、粉砕されずにショートパスを起こしやすいのでトナーの性能という点から好ましくない。また回転子３１４と固定子３１０との間の間隔が０．５ｍｍより小さい場合、装置自体の負荷が大きくなるのと同時に、粉砕時に過粉砕されて磁性酸化鉄粒子が遊離しやすい。さらに、過粉砕されることにより、熱によるトナー粒子の表面変質や機内融着を起こしやすいのでトナー生産性という点から好ましくない。
【０２３４】
また、粉砕機は、回転子及び固定子の粉砕面の表面粗さを適切な状態に制御することで、遊離磁性酸化鉄粒子の発生を制御し、良好な現像性、転写性ならびに帯電性を有する磁性トナーを得ることが出来る。即ち、回転子３１４と固定子３１０の粉砕面の中心線平均粗さＲａを１０．０μｍ以下、より好ましくは２．０乃至１０．０μｍ、また、最大粗さＲｙを６０．０μｍ以下、より好ましくは２５．０乃至６０．０μｍ、また、十点平均粗さＲｚを４０．０μｍ以下、より好ましくは２０．０乃至４０．０μｍとすることが良い。回転子及び固定子の粉砕面の中心線平均粗さＲａが１０．０μｍ超、また、最大粗さＲｙが６０．０μｍ超、また、十点平均粗さＲｚが４０．０μｍ超の場合、粉砕時に過粉砕されて磁性酸化鉄粒子が遊離しやすい。さらに、過粉砕されることにより、熱によるトナー粒子の表面変質、特にトナー粒子表面に存在する磁性酸化鉄粒子の遊離や機内融着を起こしやすいのでトナー生産性という点から好ましくない。
【０２３５】
また、表面粗さの各解析パラメータの値は、非接触で測定が可能なレーザーフォーカス変位計ＬＴ−８１００（（株）キーエンス製）及び表面形状計測ソフトＴｒｅｓ−Ｖａｌｌｅ Ｌｉｔｅ（三谷商事（株）社製）を使用して測定し、測定ポイントをランダムにずらしてそれぞれ数回測定し、その平均値から求める。また、このとき、基準長さの設定を８ｍｍ、カットオフ値の設定を０．８ｍｍ、移動速度の設定を９０μｍ／ｓｅｃとして測定する。
【０２３６】
表面粗さの解析パラメータの中で、中心線粗さＲａは、粗さ曲線からその中心線の方向に基準長さＬの部分を抜き取り、その抜き取り部分の中心線をＸ軸、縦倍率の方向をＺ軸とし、粗さ曲線をＺ＝ｆ（ｘ）で表した時、以下の式で求めることにより決定する。
【０２３７】
【数５】

【０２３８】
また、最大粗さＲｙは、粗さ曲線からその平均線の方向に基準長さだけ抜き取り、この抜き取り部分の山頂部と谷底部との間隔を粗さ曲線の縦倍率の方向に測定することによって決定する。また、十点平均粗さＲｚは、粗さ曲線からその平均線の方向に基準長さだけ抜き取り、この抜き取り部分の平均線から縦倍率の方向に測定した、最も高い山頂から５番目までの山頂標高の絶対値の平均値と、最も低い谷底部から５番目までの谷底標高の絶対値の平均との和を求めることによって決定する。
【０２３９】
回転子及び／又は固定子の粉砕面の粗面化処理としては、公知の方法が用いられる。
【０２４０】
しかしながら、回転子及び／又は固定子の粉砕面の母材を粗面化処理しただけの機械式粉砕機では、回転子及び／又は固定子の粉砕面の摩耗が短時間で発生し、トナー生産効率上好ましくなく、回転子及び／又は固定子の粉砕面の耐摩耗処理が必要となる。
【０２４１】
回転子及び／又は固定子の粉砕面の母材を前工程として粗面化処理し、後工程として母材を耐摩耗処理することにより、容易に遊離磁性酸化鉄の発生を抑え、良好な現像性を維持できるトナーが得られるとともに、回転子及び固定子の粉砕面の摩耗を低下させ、長期に渡り安定的にトナーを粉砕することが可能である。
【０２４２】
前記回転子及び／又は固定子の粉砕面の耐摩耗処理としては、公知の方法が用いられるが、この中で窒化による処理が最も好ましい。
【０２４３】
前記窒化とは、加工材料の耐摩耗性と耐疲労性を向上させることを目的とする表面硬化処理法で、適当な温度で適当な時間加熱し、加工材料の表面全体または部分的に窒素を拡散させ、窒化層を形成させる熱処理である。
【０２４４】
回転子及び／又は固定子の粉砕面の母材を前処理として粗面化処理し、後工程として母材を窒化処理することにより、容易に遊離磁性酸化鉄粒子の発生を抑えることができ、良好な現像性を維持できるトナーが得られるとともに、回転子及び固定子の粉砕面の摩耗を低下させ、長期に渡り安定的に混練物を粉砕することが可能となり、トナー生産効率において好ましい。
【０２４５】
混練物の粉砕方法は、粉砕工程前の第１分級工程を必要としない為、トナー粒子が微粒子化されることにより粒子間の静電凝集が高まり、本来は第２分級手段に送られるトナー粒子が再度第１分級手段に循環されることにより過粉砕となった微粉及び超微粉が発生しない。更に、シンプルな構成に加え、粉砕原料を粉砕するのに多量のエアーを必要としない為、電力消費が低く、エネルギーコストを低く抑えることができる。
【０２４６】
次に、トナー製造方法を構成している分級手段として好ましく用いられる気流式分級機について説明する。
【０２４７】
本発明に使用される好ましい多分割気流式分級機の一例として、図６（断面図）に示す形式の装置を一具体例として例示する。
【０２４８】
図６において、側壁２２及びＧブロック２３は分級室の一部を形成し、分級エッジブロック２４及び２５は分級エッジ１７及び１８を具備している。Ｇブロック２３は左右に設置位置をスライドさせることが可能である。また、分級エッジ１７及び１８は、軸１７ａ及び１８ａ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２４及び２５は左右に設置位置をスライドさせることが可能であり、それに伴ってそれぞれのナイフエッジ型の分級エッジ１７及び１８も左右にスライドする。この分級エッジ１７及び１８により、分級室３２の分級域３０は３分割されている。
【０２４９】
原料粉体を導入する為の原料供給口４０を原料供給ノズル１６の最後端部に有し、該原料供給ノズル１６の後端部に高圧エアーノズル４１と原料粉体導入ノズル４２とを有し、且つ分級室３２に開口部を有する原料供給ノズル１６を側壁２２の右側に設け、該原料供給ノズル１６の下部接線の延長方向に対して長楕円弧を描く様にコアンダブロック２６が設置されている。分級室３２の左部ブロック２７は、分級室３２の右側方向にナイフエッジ型の入気エッジ１９を具備し、更に分級室３２の左側には分級室３２に開口する入気管１４及び１５を設けてある。また、図６に示すように、入気管１４及び１５には、ダンパーの如き第１気体導入調節手段２０及び第２気体導入調節手段２１と静圧計２８及び２９を設けてある。
【０２５０】
分級エッジ１７、１８、Ｇブロック２３及び入気エッジ１９の位置は、被分級処理原料であるトナーの種類及び所望の粒径により調整される。
【０２５１】
また、分級室３２の上面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１１、１２及び１３を有し、排出口１１、１２及び１３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如き開閉手段を設けて良い。
【０２５２】
原料供給ノズル１６は直角筒部と角錘筒部とからなり、直角筒部の内径と角錘筒部の最も狭い個所の内径の比を２０：１から１：１、好ましくは１０：１から２：１に設定すると、良好な導入速度が得られる。
【０２５３】
以上の様に構成してなる多分割分級域での分級操作は、例えば次の様にして行う。即ち、排出口１１、１２及び１３の少なくとも一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１６中を該減圧によって流動する気流と高圧エアー供給ノズル４１から噴射される圧縮エアーのエゼクター効果により、好ましくは流速１０〜３５０ｍ／ｓの速度で粉体を原料供給ノズル１６を介して分級室に噴射し、分散する。
【０２５４】
分級室に導入された粉体中の粒子は、コアンダブロック２６のコアンダ効果による作用と、その際流入する空気の如き気体の作用とにより湾曲面を描いて移動し、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１８の外側の第１分画、中間の粒子は分級エッジ１８と１７の間の第２分画、小さい粒子は分級エッジ１７の内側の第３分画に分級され、分級された大きい粒子は排出口１１より排出され、分級された中間の粒子は排出口１２より排出され、分級された小さい粒子は排出口１３よりそれぞれ排出される。
【０２５５】
上記の粉体の分級において、分級点は、粉体が分級室３２内へ飛び出す位置であるコアンダブロック２６の下端部分に対する分級エッジ１７及び１８のエッジ先端位置によって主に決定される。更に、分級点は、分級気流の吸引流量或いは原料供給ノズル１６からの粉体の噴出速度等の影響を受ける。
【０２５６】
また、トナーの製造方法及び製造システムにおいては、粉砕及び分級条件をコントロールすることにより、重量平均径が５〜１２μｍ（特に、５〜１０μｍ）である粒径のシャープな粒度分布を有するトナーを効率良く生成することができる。
【０２５７】
混合機としては、ヘンシェルミキサー（三井鉱山社製）；スーパーミキサー（カワタ社製）；リボコーン（大川原製作所社製）；ナウターミキサー、タービュライザー、サイクロミックス（ホソカワミクロン社製）；スパイラルピンミキサー（太平洋機工社製）；レーディゲミキサー（マツボー社製）が挙げられ、混練機としては、ＫＲＣニーダー（栗本鉄工所社製）；ブス・コ・ニーダー（Ｂｕｓｓ社製）；ＴＥＭ型押し出し機（東芝機械社製）；ＴＥＸ二軸混練機（日本製鋼所社製）；ＰＣＭ混練機（池貝鉄工所社製）；三本ロールミル、ミキシングロールミル、ニーダー（井上製作所社製）；ニーデックス（三井鉱山社製）；ＭＳ式加圧ニーダー、ニダールーター（森山製作所社製）；バンバリーミキサー（神戸製鋼所社製）が挙げられ、粉砕機としては、カウンタージェットミル、ミクロンジェット、イノマイザ（ホソカワミクロン社製）；ＩＤＳ型ミル、ＰＪＭジェット粉砕機（日本ニューマチック工業社製）；クロスジェットミル（栗本鉄工所社製）；ウルマックス（日曹エンジニアリング社製）；ＳＫジェット・オー・ミル（セイシン企業社製）；クリプトロン（川崎重工業社製）；ターボミル（ターボ工業社製）が挙げられ、分級機としては、クラッシール、マイクロンクラッシファイアー、スペディッククラシファイアー（セイシン企業社製）；ターボクラッシファイアー（日清エンジニアリング社製）；ミクロンセパレータ、ターボプレックス（ＡＴＰ）、ＴＳＰセパレータ（ホソカワミクロン社製）；エルボージェット（日鉄鉱業社製）、ディスパージョンセパレータ（日本ニューマチック工業社製）；ＹＭマイクロカット（安川商事社製）が挙げられ、粗粒などをふるい分けるために用いられる篩い装置としては、ウルトラソニック（晃栄産業社製）；レゾナシーブ、ジャイロシフター（徳寿工作所社）；バイブラソニックシステム（ダルトン社製）；ソニクリーン（新東工業社製）；ターボスクリーナー（ターボ工業社製）；ミクロシフター（槙野産業社製）；円形振動篩いが挙げられる。
【０２５８】
本発明のトナーを製造するに際しては、この粉砕工程及び分級工程に、上記で説明した構成の装置システムを用いることが好ましい。
【０２５９】
次に、図１１を参照しながら、本発明の画像形成方法の一例を説明する。
【０２６０】
一次帯電器７０２で感光ドラム１の表面を負極性に帯電し、レーザ光による露光７０５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、磁性ブレード７１１及び磁石７１４を内包している現像スリーブ７０４を具備する現像器７０９の乾式磁性トナー（一成分系磁性現像剤）７１０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７０４にはバイアス印加手段７１２により交互バイアス、パルスバイアス及び／または直流バイアスが印加されている。転写紙Ｐが搬送されて、転写部にくるとローラ転写手段７０２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７２３で帯電することにより、感光ドラム７０１の表面上のトナー像が接触転写手段７０２によって転写紙Ｐ上へ転写される。感光ドラム７０１から分離された転写紙Ｐは、加熱加圧ローラ定着器７０７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。トナー像は、感光ドラム７０１から中間転写体を介して転写紙Ｐに転写されても良く、中間転写体を介さなくて転写紙Ｐに転写されても良い。
【０２６１】
転写工程後の感光ドラム７０１に残留する乾式磁性トナーは、クリーニングブレードを有するクリーニング手段７０８で除去される。残留する乾式磁性トナーが少ない場合、クリーニング工程を省くことも可能である。クリーニング後の感光ドラム７０１は、イレース露光７０６により除電され、再度、一次帯電器７０２による帯電工程から始まる工程が繰り返される。
【０２６２】
感光ドラム７０１（すなわち、静電荷像担持体）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７０４は、現像部において感光ドラム７０１の表面と同方向に進むように回転する。現像スリーブ７０４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７０９内の絶縁性の乾式磁性トナー７１０は非磁性円筒面上に塗布され、かつ現像スリーブ７０４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。さらに鉄製の磁性ドクターブレード７１１を円筒表面に近接して（間隔５０μｍ〜５００μｍ）、多極永久磁石の一つの磁極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７０１と現像スリーブ７０４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７０４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当速、もしくはそれに近い速度となるようにする。磁性ドクターブレード７１１として鉄のかわりに永久磁石を用いて対向磁極を形成してもよい。現像部において現像スリーブ７０４に交流バイアスまたはパルスバイアスをバイアス手段７１２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。
【０２６３】
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力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粒子は静電像側に移転する。
【０２６４】
磁性ドクターブレード７１１のかわりに、シリコーンゴムのごとき弾性材料で形成された弾性ブレードを用いて押圧によって磁性トナー層の層厚を規制し、現像スリーブ上に磁性トナーを塗布しても良い。
【０２６５】
図１２には、バイアス印加手段７４３から電圧を印加されている接触帯電手段７４２及びコロナ転写手段７３３を有する画像形成装置が示されている。
【０２６６】
図１３には、接触帯電手段７４２及び接触転写手段７０２を有する画像形成装置が示されている。
【０２６７】
図１４においては、７０２は転写ローラーであり、中心の芯金７０２ａとその外周を形成した導電性弾性層７０２ｂとを基本構成とするものである。転写ローラー７０２は、感光ドラム７０１の表面に押圧力をもって転写材を圧接し、感光ドラム７０１の周速度と等速度或いは周速度に差をつけて回転させる。転写材はカイド７４４を通って感光ドラム７０１と転写ローラー７０２との間に搬送され、転写ローラー７０２にトナーと逆極性のバイアスを転写バイアス印加手段７２３から印加することによって感光ドラム７０１上のトナー像が転写材の表面側に転写される。次いで、転写材はガイド７４５上に送られる。
【０２６８】
導電性弾性層７０２ｂは、カーボン等の導電材を分散させたポリウレタン、エチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）等の体積抵抗１０⁶〜１０¹⁰Ωｃｍの弾性体でつくられている。
【０２６９】
好ましい転写プロセス条件としては、ローラーの当接圧が０．１６×１０^-2〜２４．５×１０^-2ＭＰａで、直流電圧が±０．２〜±１０ｋＶである。
【０２７０】
一方、図１５は接触帯電手段を示し、図１５において、７０１は回転ドラム型の静電荷像担持体（以下、感光ドラムと記す）であり、該感光ドラム７０１はアルミニウム等の導電性基層７０１ａと、その外面に形成した光導電層７０１ｂ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。
【０２７１】
７４２は帯電ローラーであり、中心の芯金７４２ａとその外周を形成した導電性弾性層７４２ｂと表面層７４２ｃとを基本構成とするものである。帯電ローラー７４２は、感光ドラム７０１の表面に押圧力をもって圧接され、感光ドラム７０１の回転に伴い従動回転する。帯電ローラー７４２は、バイアス印加手段Ｅにより電圧が印加され、帯電ローラー７４２にバイアスが印加されることで感光ドラム７０１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って静電荷像が形成され、現像手段により静電荷像はトナー像として順次可視化されていく。
【０２７２】
帯電ローラーを用いた時の好ましいプロセス条件としては、ローラーの当接圧が０．４９×１０^-2〜９８×１０^-2ＭＰａ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＝５０〜５ｋＨｚ、直流電圧＝±０．２〜±１．５ｋＶであり、直流電圧を用いた時には、直流電圧＝±０．２〜±５ｋＶである。
【０２７３】
帯電ローラー及び帯電ブレードの材質としては導電性ゴムが好ましく、その表面に離型性被膜を設けても良い。離型性被膜としては、ナイロン系樹脂、ＰＶＤＦ（ポリフッ化ビニリデン）、ＰＶＤＣ（ポリ塩化ビニリデン）が適用可能である。
【０２７４】
図１６に、本発明のプロセスカートリッジの一具体例を示す。プロセスカートリッジは、現像手段と静電荷像担持体とを少なくとも一体的にカートリッジ化し、プロセスカートリッジは、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）に着脱可能なように形成される。
【０２７５】
図１６では、現像手段７０９、ドラム状の静電荷像担持体（感光体ドラム）７０１、クリーニングブレード７０８ａを有するクリーナ７０８、一時帯電器（帯電ローラー）７４２を一体としたプロセスカートリッジ７５０が例示される。
【０２７６】
本実施例では、現像手段７０９は磁性ブレード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バイアスにより感光ドラム７０１と現像スリーブ７０４との間に所定の電界が形成され、現像工程が好適に実施されるためには、感光ドラム７０１と現像スリーブ７０４との間の距離は非常に大切である。
【０２７７】
図１７では、現像手段７０９は弾性ブレード７１１ａ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バイアスにより感光ドラム１と現像スリーブ７０４との間に所定の電界が形成され、現像工程が好適に実施されるためには、感光ドラム１と現像スリーブ７０４との間の距離は非常に大切である。
【０２７８】
図１８において使用される注入帯電工程を有するプロセスカートリッジの１具体例を示す。現像剤としては磁性トナーを使用し、現像剤担持体上の現像剤層と像担持体が非接触となるよう配置される非接触現像の画像形成装置の例である。８０１は像担持体としての回転ドラム型ＯＰＣ感光体であり、時計方向（矢印の方向）に回転駆動される。８０２は接触帯電部材としての帯電ローラーである。帯電ローラ８０２は感光体８０１に対して弾性に抗して所定の押圧力で圧接させて配設してある。ｎは感光体８０１と帯電ローラ８０２のニップ部である帯電ニップ部である。本実施例では、帯電ローラ８０２は感光体８０１との接触面である帯電ニップ部ｎにおいて対向方向（感光体表面の移動方向と逆方向）に回転駆動されている。また、帯電ローラ８０２の表面には、塗布量がおよそ一層で均一になるように前記導電性微粉末ｍが塗布される。
【０２７９】
また帯電ローラ８０２の芯金８０２ａには、図示しない帯電バイアス印加電源Ｓ１から−７００Ｖの直流電圧を帯電バイアスとして印加する。本実施例では感光体８０１の表面は帯電ローラ８０２に対する印加電圧とほぼ等しい電位（−６８０Ｖ）に直接注入帯電方式によって一様に帯電処理される。
【０２８０】
８０３はレーザダイオード、ポリゴンミラー等を含むレーザビームスキャナ（露光器）である。このレーザビームスキャナは目的の画像情報の時系列電気デジタル画素信号に対応して強度変調されたレーザ光（波長７４０ｎｍ）を出力し、該レーザ光Ｌで感光体１の一様帯電面を走査露光する。この走査露光により回転する感光体８０１に目的の画像情報に対応した静電潜像が形成される。
【０２８１】
８０４は現像装置である。感光体８０４の表面の静電潜像がこの現像装置によりトナー像として現像される。実施例の現像装置８０４は、絶縁性の負帯電性磁性トナーを用いた、非接触型の反転現像装置である。磁性トナー４ｄには磁性トナー粒子（ｔ）及び導電性微粉末（ｍ）が含有されている。
【０２８２】
８０４ａは現像剤担持搬送部材としての、マグネットロール８０４ｂを内包させた直径１６ｍｍの非磁性現像スリーブである。この現像スリーブ８０４ａは感光体１に対して３２０μｍの離間距離をあけて対向配設し、感光体８０１との対向部である現像部（現像領域部）ａにて感光体８０１の回転方向と順方向に感光体８０１の周速の１２０％の周速比で回転される。
【０２８３】
この現像スリーブ８０４ａ上に、磁性トナー８０４ｄが弾性ブレード８０４ｃによって薄層にコートされる。磁性トナー８０４ｄは、弾性ブレード８０４ｃによって現像スリーブ８０４ａ上での層厚が規制されるとともに電荷が付与される。
【０２８４】
現像スリーブ８０４ａにコートされた磁性トナー８０４ｄは、現像スリーブ８０４ａが回転することによって、感光体８０１と該現像スリーブ８０４ａの対向部である現像部ａに搬送される。
【０２８５】
また、現像スリーブ８０４ａには現像バイアス印加電源Ｓ２により現像バイアス電圧が印加される。現像バイアス電圧は、−４２０Ｖの直流電圧と、周波数１５００Ｈｚ、ピーク間電圧１６００Ｖ（電界強度５×１０⁶Ｖ／ｍ）の矩形の交流電圧とを重畳したものを用いて、現像スリーブ８０４ａと感光体８０１の間で一成分ジャンピング現像を行なわせる。本発明においては、導電性微粉末ｍは帯電ローラーに塗布されるだけではなく、磁性トナーに外添させておいても良い。
【０２８６】
導電性微粉末ｍの存在により、帯電ローラ８０２の感光体８０１への緻密な接触性と接触抵抗を維持できるため、該帯電ローラ８０２による感光体８０１の直接注入帯電を行なわせることができる。
【０２８７】
帯電ローラ８０２が導電性微粉末ｍを介して密に感光体８０１に接触し、導電性微粉末ｍが感光体８０１表面を隙間なく摺擦する。これにより、帯電ローラ８０２による感光体８０１の帯電を、放電現象を用いない、安定かつ安全な直接注入帯電が支配的とすることが可能になり、従来のローラ帯電等では得られなかった高い帯電効率が得られる。従って、帯電ローラ８０２に印加した電圧とほぼ同等の電位を感光体８０１に与えることができる。
【０２８８】
感光ドラム８０１上のトナー像は転写部ｂで転写バイアス印加電源Ｓ３による転写バイアスを印加されている転写ローラ８０５により転写材Ｐへ転写される。転写ローラ８０５は転写時には転写材Ｐを線圧１〜８０ｇ／ｃｍで押圧している。
【０２８９】
【実施例】
以上本発明の基本的な構成と特色について述べたが、以下実施例にもとづいて具体的に本発明について説明する。しかしながら、これによって本発明の実施の態様がなんら限定されるものではない。実施例中の部数は質量部である。
【０２９０】
実施例に用いられる樹脂を表１に、ワックスを表２に、磁性酸化鉄粒子を表３に記す。スチレン系樹脂は溶液重合又は懸濁重合により合成し、ポリエステル樹脂は脱水縮合法により合成した。以下に磁性酸化鉄粒子の製造法を示す。
【０２９１】
・磁性酸化鉄粒子の製造例１
硫酸第一鉄溶液中に、Ｆｅ²⁺に対して０．９５当量の水酸化ナトリウム水溶液を混合した後、Ｆｅ（ＯＨ）₂を含む第一鉄塩水溶液の生成を行った。その後、ケイ酸ソーダを鉄元素に対してケイ素元素換算で、１．０質量％となるように添加した。次いでＦｅ（ＯＨ）₂を含む第一鉄塩水溶液に温度９０℃において空気を通気してｐＨ６〜７．５の条件下で酸化反応をすることにより、ケイ素元素を含有する磁性酸化鉄粒子を生成した。さらにこの懸濁液に（鉄元素に対してケイ素元素換算）０．１質量％のケイ酸ソーダを溶解した水酸化ナトリウム水溶液を残存Ｆｅ²⁺に対して１．０５当量添加して、さらに温度９０℃で加熱しながら、ｐＨ８〜１１．５の条件下で酸化反応してケイ素元素を含有した磁性酸化鉄粒子を生成させた。生成した磁性酸化鉄粒子を常法により洗浄・ろ過・乾燥した。
【０２９２】
得られた磁性酸化鉄粒子の一次粒子は、凝集して凝集体を形成しているので、ミックスマーラー（新東工業株式会社製）を使用して磁性酸化鉄粒子の凝集体に圧縮力及びせん断力を付与して、該凝集体を解砕して磁性酸化鉄粒子を一次粒子にするとともに、磁性酸化鉄粒子の表面を平滑にし、表３に示すような特性を有する磁性酸化鉄粒子１を得た。磁性酸化鉄粒子の平均粒径は０．２１μｍであった。磁性酸化鉄粒子１の表面は、酸化鉄と酸化ケイ素とで形成されていた。
【０２９３】
・磁性酸化鉄粒子の製造例２
製造例１と同様、ケイ素元素量を変え製造例２の磁性酸化鉄粒子２を得た。磁性酸化鉄粒子２の表面は、酸化鉄と酸化ケイ素とで形成されていた。
【０２９４】
・磁性酸化鉄粒子の製造例３，４
製造例２で得られた磁性酸化鉄粒子のろ過工程前に、スラリー液中に硫酸アルミニウムを所定量加え、ｐＨを６〜８の範囲に調整して、水酸化アルミニウムとして、磁性酸化鉄粒子の表面処理を行い製造例３，４の磁性酸化鉄粒子３，４を得た。製造例３，４の磁性酸化鉄は、製造例１と同様、ミックスマーラーによって圧密解砕処理を行った。磁性酸化鉄粒子３及び４の表面は、酸化鉄と酸化ケイ素と酸化アルミと水酸化アルミとで形成されていた。
【０２９５】
・磁性酸化鉄粒子の製造例５，６
製造例１の第一段階の反応時に所定の全ケイ素含有量を投入し、さらに、投入する水酸化ナトリウム水溶液をＦｅ²⁺に対し１当量を超える量にし、ｐＨ調整を変えることにより製造例５，６の磁性酸化鉄粒子５，６を得た。磁性酸化鉄粒子５及び６の表面は、酸化鉄と酸化ケイ素とで形成されていた。
【０２９６】
・磁性酸化鉄粒子の製造例７
硫酸第一鉄水溶液中に、鉄元素に対しケイ素元素の含有率が、１．８％となるようにケイ酸ソーダを添加した後、鉄イオンに対して１．０〜１．１当量の水酸化アルカリ水溶液を混合し、Ｆｅ（ＯＨ）₂を含む第一鉄塩水溶液の生成を行った。次いで、水溶液のｐＨを９に維持しながら、温度８５℃において空気を通気して、酸化反応をすることにより、ケイ素元素を含有した磁性酸化鉄粒子を生成した。さらに、この懸濁液に当初のアルカリ量（ケイ酸ソーダのナトリウム成分及び水酸化アルカリのナトリウム成分）に対し、１．１当量となるように硫酸第一鉄水溶液を加えた後、溶液のｐＨを８に維持して、空気を吹き込みながら酸化反応をすすめ、酸化反応の終期にｐＨを弱アルカリ側になるように調整し、磁性酸化鉄粒子を得た。
【０２９７】
生成した磁性酸化鉄粒子を常法により、洗浄・ろ過・乾燥し、次いで凝集している磁性酸化鉄粒子を通常の解砕処理し、磁性酸化鉄粒子７を得た。磁性酸化鉄粒子７の表面は、酸化鉄と酸化ケイ素とで形成されていた。
【０２９８】
実施例１
・結着樹脂Ａ １００部
・磁性酸化鉄粒子３ ９０部
・ワックスｃ ４部
・アゾ系鉄錯体化合物Ａ ２部
上記材料をヘンシェルミキサーで前混合した後、１３０℃に設定した二軸混練押し出し機によって、溶融混練した。
【０２９９】
得られた混練物を冷却し、カッターミルにて１ｍｍ以下に粗粉砕し、粗粉砕物を得た。得られた粗粉砕物を図２に示す機械式粉砕機３０１で微粉砕し、得られた微粉砕品を図２に示す多分割分級機を用いて分級し、重量平均粒径６．５μｍの磁性トナー粒子を得た。本実施例では、機械式粉砕機３０１の回転子３１４及び固定子３１０の粉砕面を窒化により耐摩耗処理を行ったものを使用した。処理後の表面粗さは中心線粗さＲａが１．１μｍ、最大粗さＲｙを２０．６μｍ、十点平均粗さを１２．３μｍであった。回転子３１４の周速を１１７ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４２℃であった。
【０３００】
得られた磁性トナー粒子１００部に対し、ヘキサメチルジシラザン１５質量％とジメチルシリコーン１５質量％で疎水化処理したメタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇの負帯電性疎水性シリカ微粉体を１．２部とチタン酸ストロンチウム１．０部をヘンシェルミキサーＦＭ１０Ｃ／ｌ（三井鉱山株式会社製）にて、乾式磁性トナーの見掛け体積充填率が１２％となるように磁性トナーを充填し図２４に示したＹ０羽根とＳ０羽根を用いて、回転数４５．００ｓ^-1で１分間撹拌し、その後続けて５０．００ｓ^-1で２分間撹拌処理を行い磁性トナーＮｏ．１を調製した。
【０３０１】
トナー内添処方、粉砕条件及び物性値を表４に記し、磁性トナーＮｏ．１の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。
【０３０２】
磁性トナーＮｏ．１を、図１３の形式の市販のＬＢＰプリンター（ＬＢＰ−９３０，キヤノン社製）をプロセススピード２３５ｍｍ／ｓｅｃに相当する１．５倍のプリントスピードに改造し、常温常湿（２３℃，６５％ＲＨ）の環境と低温低湿（１５℃，１０％ＲＨ）の環境と高温高湿（３０℃，８０％ＲＨ）の環境でそれぞれ１万５千枚のプリント試験を行った。
【０３０３】
画像濃度はマクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して、反射濃度測定を行い、５ｍｍ角の画像を測定した。カブリは反射濃度計（リフレクトメーター モデル ＴＣ−６ＤＳ 東京電色社製）を用いて行い、画像形成後の白地部反射濃度最悪値をＤｓ、画像形成前の転写材の反射平均濃度をＤｒとし、Ｄｓ−Ｄｒをカブリ量としてカブリの評価を行った。数値の少ない方がカブリ抑制が良い。
【０３０４】
これらの評価を、初期、１５０００枚時、機外に一日放置した後に行った。
【０３０５】
転写効率の評価については、市販のＬＢＰプリンター（ＬＢＰ−９５０，キヤノン社製）で２３℃，６５％ＲＨの環境下で、初期及び１万枚耐久後の転写性変動を評価した。転写紙としては７５ｇ／ｃｍ²の普通紙を使用した。転写性はベタ黒の６ＰＣ感光体上の転写残トナー及び転写前トナーをポリエステルテープによりテーピングして剥ぎ取り、紙上に貼ったもののマクベス濃度からテープのみを貼ったもののマクベス濃度を差し引いた数値から計算して評価した。
【０３０６】
磁性トナーの消費量、ライン幅の評価については、キヤノン製レーザービームプリンターＬＢＰ−１７６０を１６枚／分から２４枚／分に改造した画像形成装置を用いて、常温常湿環境（２３℃，６５％ＲＨ）で１０００枚画出し後、６００ｄｐｉの１０ドット横線パターンで潜像ライン幅が約４２０μｍになるように設定し、Ａ４サイズ紙に印字率４％の画像を５０００枚出力し、現像器内の磁性トナー量の変化から消費量を求めた。さらにベタ黒画像を出力し、このときの画像濃度を確認した。
【０３０７】
さらに、６００ｄｐｉの１０ドット横線パターン潜像（潜像ライン幅約４２０μｍ）を１ｃｍ間隔で書かせ、これを現像し、ＰＥＴ製のＯＨＰ上に転写、定着させた。得られた横線パターン画像を表面粗さ計サーフコーダーＳＥ−３０Ｈ（小坂研究所製）を用い、横線ラインのトナーの載り方を表面粗さのプロフィールとして得、このプロフィールの幅からライン幅を求めた。ライン幅は潜像ライン幅よりもわずかに太い時に、最も鮮鋭性の高い画像が得られ、潜像ライン幅よりも細くなるに従い細線の再現性などが低下する。
【０３０８】
画像濃度が高く、ライン幅も適正でトナー消費量が少ない磁性トナーが好ましいものであり、画像濃度が低くてトナー消費量の少ない磁性トナーや、ライン幅が細くてトナー消費量の少ない磁性トナーは好ましい形態ではない。
【０３０９】
画質の評価については上記画出し試験機を用いて、孤立した１ドットのパターンを画出しし、光学顕微鏡で画像を観察してドット再現性を評価した。
Ａ：潜像からの磁性トナーのはみ出しが全く無く、ドットを完全に再現している
Ｂ：潜像からの磁性トナーのはみ出しがところどころある。
Ｃ：潜像からの磁性トナーのはみ出しが少しある
Ｄ：潜像からの磁性トナーのはみ出しが多い
【０３１０】
尾引きの評価については、上記画出し試験機を用いて、４ドットの横ラインを１７５ドットスペースに印字した長さ約２０ｃｍのパターンを画出しし、５０本中のライン上で目視で尾引いたラインの数を数えた。
Ａ：発生なし
Ｂ：２本以下
Ｃ：３〜６本
Ｄ：７〜１４本
Ｅ：１５本以上
【０３１１】
評価結果を表８〜１２に示す。
【０３１２】
実施例２
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．２を作製した。但し、回転子３１４の周速を１２５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３７℃であった。得られた磁性トナーＮｏ．２の物性値を表４に示し、磁性トナーＮｏ．２の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１３】
実施例３
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．３を作製した。但し、回転子３１４の周速を１５０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は５３℃であった。得られた磁性トナーＮｏ．３の物性値を表４に示し、磁性トナーＮｏ．３の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１４】
実施例４
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．４を作製した。但し、回転子３１４の周速を１１４ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４５℃であった。得られた磁性トナーＮｏ．４の物性値を表４に示し、磁性トナーＮｏ．４の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１５】
実施例５
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．５を作製した。但し、回転子３１４の周速を１１５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４０℃であった。得られた磁性トナーＮｏ．５の物性値を表４に示し、磁性トナーＮｏ．５の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１６】
実施例６
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．６を作製した。但し、回転子３１４の周速を１４４ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は５５℃であった。得られた磁性トナーＮｏ．６の物性値を表４に示し、磁性トナーＮｏ．６の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１７】
実施例７
表４に記載の処方で実施例１と同様に磁性トナーＮｏ．７を作製した。但し、粉砕工程の前に図２に示す機械式粉砕機３０１で中粉砕を行った。この時の粉砕条件は粉砕工程と同様の条件で行った。但し、回転子３１４と固定子３１０の間隙を２．０ｍｍとして粉砕した。その後、回転子３１４の周速を１４４ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は５５℃であった。得られた磁性トナーＮｏ．７の物性値を表４に示し、磁性トナーＮｏ．７の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１８】
実施例８
表４に記載の処方で実施例７と同様に磁性トナーＮｏ．８を作製した。得られた磁性トナーＮｏ．８の物性値を表４に示し、磁性トナーＮｏ．８の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３１９】
実施例９
表４に記載の処方で実施例７と同様に磁性トナーＮｏ．９を作製した。得られた磁性トナーＮｏ．９の物性値を表４に示し、磁性トナーＮｏ．９の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２０】
実施例１０
表５に記載の処方で実施例７と同様に磁性トナーＮｏ．１０を作製した。得られた磁性トナーＮｏ．１０の物性値を表５に示し、磁性トナーＮｏ．１０の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２１】
実施例１１
表５に記載の処方で実施例１と同様に磁性トナーＮｏ．１１を作製した。但し、回転子３１４の周速を９０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３０℃であった。得られた磁性トナーＮｏ．１１の物性値を表５に示し、磁性トナーＮｏ．１１の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２２】
実施例１２
表５に記載の処方で実施例１と同様に磁性トナーＮｏ．１２を作製した。但し、回転子３１４の周速を１２０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は５０℃であった。得られた磁性トナーＮｏ．１２の物性値を表５に示し、磁性トナーＮｏ．１２の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２３】
実施例１３
表５に記載の処方で実施例１と同様に磁性トナーＮｏ．１３を作製した。但し、その表面粗さ、中心線粗さＲａを１．７μｍ、最大粗さＲｙを３５．６μｍ、十点平均粗さを２１．３μｍとした。回転子３１４の周速を１５５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４６℃であった。得られた磁性トナーＮｏ．１３の物性値を表５に示し、磁性トナーＮｏ．１３の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２４】
実施例１４
表５に記載の処方で実施例１と同様に磁性トナーＮｏ．１４を作製した。但し、回転子３１４の周速を１３５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３３℃であった。得られた磁性トナーＮｏ．１４の物性値を表５に示し、磁性トナーＮｏ．１４の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２５】
実施例１５
表５に記載の処方で実施例１と同様に磁性トナーＮｏ．１５を作製した。但し、回転子３１４の周速を１１５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４８℃であった。得られた磁性トナーＮｏ．１５の物性値を表５に示し、磁性トナーＮｏ．１５の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２６】
比較例１
表５に記載の処方で実施例１と同様に比較磁性トナー（ｉ）を作製した。但し、回転子及び固定子を鏡面処理にしその後窒化により耐摩耗処理を行ったものを使用した。処理後の粉砕面の粗さは中心線粗さＲａが０．９μｍ、最大粗さＲｙが９．０μｍ、十点平均粗さが６．４μｍであった。回転子３１４の周速を１５０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は５３℃であった。得られた比較磁性トナー（ｉ）の物性値を表５に示し、比較磁性トナー（ｉ）の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２７】
比較例２
表５に記載の処方で実施例１と同様に比較磁性トナー（ｉｉ）を作製した。但し、回転子，固定子をブラスト処理しその後窒化により耐摩耗処理を行ったものを使用した。処理後の粉砕面の粗さは中心線粗さＲａが３．２μｍ、最大粗さＲｙが４３．５μｍ、十点平均粗さが３５．４μｍであり、回転子３１４の周速を９０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．０ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３１℃であった。得られた比較磁性トナー（ｉｉ）の物性値を表５に示し、比較磁性トナー（ｉｉ）の円形度と平均粒子径の関係を図２１に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２８】
比較例３
表５に記載の処方で比較磁性トナー（ｉｉｉ）を作製した。粉砕工程は衝突式気流粉砕を用いた微粉砕機で粉砕し、得られた微粉砕粉末をコアンダ効果を利用した多分割分級機を用いて分級した。得られた比較磁性トナー（ｉｉｉ）の物性値を表５に示し、比較磁性トナー（ｉｉｉ）の円形度と平均粒子径の関係を図２０に示し、重量平均径Ｘとピーク粒度に対する半値幅の関係を図２２に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３２９】
比較例４
表５に記載の処方で比較磁性トナー（ｉｖ）を作製した。粉砕工程は衝突式気流粉砕を用いた微粉砕機で粉砕し、得られた微粉砕粉末をコアンダ効果を利用した多分割分級機を用いて分級し、分級後にハイブリタイザーにより粒子の形状及び表面性を改質した。得られた比較磁性トナー（ｉｖ）の物性値を表５に示す。実施例１と同様の試験をした結果を表８〜１２に示す。
【０３３０】
実施例１６〜２０
実施例１，２，１２，１３，１５で用いた磁性トナーＮｏ．１，２，１２，１３及び１５を使用し、市販のＬＢＰプリンター（ＬＢＰ−２５０，キヤノン社製）に使用されるカートリッジを図１８において説明した注入帯電工程を有するカートリッジに改造したものを使用して画出し評価をおこなった。改造内容は、帯電ローラーにアルミニウム元素を含有する抵抗が１００Ω・ｃｍの酸化亜鉛微粉末を導電性微粉末を均一に塗布し、帯電ローラには帯電バイアス印加電源Ｓ１から−７００Ｖの直流電圧を帯電バイアスとして印加した。
【０３３１】
本実施例ではＯＰＣ感光体１の表面は帯電ローラ２に対する印加電圧とほぼ等しい電位（−６８０Ｖ）に直接注入帯電方式によって一様に帯電処理された。現像バイアス電圧は、−４２０Ｖの直流電圧と、周波数１５００Ｈｚ、ピーク間電圧１６００Ｖ（電界強度５×１０⁶Ｖ／ｍ）の矩形の交流電圧とを重畳したものを用いて、現像スリーブ４ａとＯＰＣ感光体１の間で一成分ジャンピング現像を行わせた。
【０３３２】
このカートリッジを用い、市販のＬＢＰプリンター（ＬＢＰ−２５０，キヤノン社製）をプロセススピード１２０ｍｍ／ｓｅｃとなるように改造し実施例１と同様にトナー消費量，画像濃度，ライン幅，ドット再現性，尾引きの評価を行った。その結果を表１３に示す。
【０３３３】
【表１】

【０３３４】
【表２】

【０３３５】
【表３】

【０３３６】
【化１５】

【０３３７】
【表４】

【０３３８】
【表５】

【０３３９】
【表６】

【０３４０】
【表７】

【０３４１】
【表８】

【０３４２】
【表９】

【０３４３】
【表１０】

【０３４４】
【表１１】

【０３４５】
【表１２】

【０３４６】
【表１３】

【０３４７】
実施例２１
・結着樹脂Ｂ １００部
・磁性酸化鉄粒子３ ９０部
・ワックスｃ ４部
・アゾ系鉄錯体化合物Ａ ２部
上記材料をヘンシェルミキサーで前混合した後、１３０℃に設定した二軸混練押し出し機によって、溶融混練した。
【０３４８】
得られた混練物を冷却し、カッターミルにて１ｍｍ以下に粗粉砕し、トナー製造用粉体原料である粗粉砕物を得た。得られた粉体原料を図２に示す機械式粉砕機３０１で微粉砕し、得られた微粉砕品を図２に示す多分割分級機を用いて分級し、重量平均粒径６．５μｍの磁性トナー粒子を得た。本実施例では、機械式粉砕機３０１の回転子３１４及び固定子３１０の粉砕面を粗面化処理することによりその表面粗さを、中心線粗さＲａ＝５．９μｍ、最大粗さＲｙ＝３２．４μｍ、十点平均粗さ＝２１．４μｍとし、窒化により耐摩耗処理を行った。また、回転子３１４の周速を１１７ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４２℃であった。
【０３４９】
得られた磁性トナー粒子１００部に対し、ヘキサメチルジシラザン１５質量％とジメチルシリコーン１５質量％で疎水化処理したメタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇの疎水性シリカ微粉体１．２部とチタン酸ストロンチウム１．０部を外添混合して磁性トナーＮｏ．１６を調製した。
【０３５０】
トナー内添処方、粉砕条件及び物性値を表１４及び表１５に記し、磁性トナーＮｏ．１６の円形度と平均粒子径の関係を図２５に示す。
【０３５１】
磁性トナーＮｏ．１６を、図１３の形式の市販のＬＢＰプリンター（ＬＢＰ−９３０，キヤノン社製）を１．５倍のプリントスピードに改造し、２３℃，６５％ＲＨの環境と、１５℃，１０％ＲＨの環境と３０℃，８０％ＲＨの環境で１万５千枚のプリント試験を行った。評価結果を表１６〜１８に示す。
【０３５２】
画像濃度はマクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して、反射濃度測定を行い、５ｍｍ角の画像を測定した。カブリは反射濃度計（リフレクトメーター モデル ＴＣ−６ＤＳ 東京電色社製）を用いて行い、画像形成後の白地部反射濃度最悪値をＤｓ、画像形成前の転写材の反射平均濃度をＤｒとし、Ｄｓ−Ｄｒをカブリ量としてカブリの評価を行った。数値の少ない方がカブリ抑制が良い。
【０３５３】
これらの評価を、初期、１５０００枚時、機外に一日放置した後に行った。
【０３５４】
転写効率の評価については、市販のＬＢＰプリンター（ＬＢＰ−９３０，キヤノン社製）で２３℃，６５％ＲＨの環境下で、初期及び１万枚耐久後の転写性変動を評価した。転写紙としては７５ｇ／ｃｍ²の普通紙を使用した。転写性はベタ黒の感光体上の転写残トナー及び転写前トナーをポリエステルテープによりテーピングして剥ぎ取り、紙上に貼ったもののマクベス濃度からテープのみを貼ったもののマクベス濃度を差し引いた数値から計算して評価した。評価結果を表１９に示す。
【０３５５】
実施例２２
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．１７を作製した。但し、回転子３１４の周速を１２５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３７℃であった。得られた磁性トナーＮｏ．１７の物性値を表１４及び表１５に示し、磁性トナーＮｏ．１７の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３５６】
実施例２３
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．１８を作製した。但し、回転子３１４の周速を１５０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は６３℃であった。得られた磁性トナーＮｏ．１８の物性値を表１４及び表１５に示し、磁性トナーＮｏ．１８の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３５７】
実施例２４
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．１９を作製した。但し、回転子３１４の周速を１１４ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４５℃であった。得られた磁性トナーＮｏ．１９の物性値を表１４及び表１５に示し、磁性トナーＮｏ．１９の円形度と平均粒子径の関係を図２６に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３５８】
実施例２５
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．２０を作製した。但し、回転子３１４の周速を１１５ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４０℃であった。得られた磁性トナーＮｏ．２０の物性値を表１４及び表１５に示し、磁性トナーＮｏ．２０の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３５９】
実施例２６
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．２１を作製した。但し、回転子３１４の周速を１４４ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は６０℃であった。得られた磁性トナーＮｏ．２１の物性値を表１４及び表１５に示し、磁性トナーＮｏ．２１の円形度と平均粒子径の関係を図２６に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６０】
実施例２７
表１４に記載の処方で実施例２１と同様に磁性トナーＮｏ．２２を作製した。但し、回転子３１４の周速を９０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３０℃であった。得られた磁性トナーＮｏ．２２の物性値を表１４及び表１５に示し、磁性トナーＮｏ．２２の円形度と平均粒子径の関係を図２６に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６１】
比較例５
表１４に記載の処方で実施例２１と同様に比較磁性トナー（ｖ）を作製した。但し、粉砕面の表面粗さを、中心線粗さＲａ＝１．８μｍ、最大粗さＲｙ＝１３．５μｍ、十点平均粗さ＝９．８μｍとし、窒化により耐摩耗処理を行った。回転子３１４の周速を１５０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は６３℃であった。得られた比較磁性トナー（ｖ）の物性値を表１４及び表１５に示し、比較磁性トナー（ｖ）の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６２】
比較例６
表１４に記載の処方で実施例２１と同様に比較磁性トナー（ｖｉ）を作製した。但し、粉砕面の表面粗さを、中心線粗さＲａ＝１２．３μｍ、最大粗さＲｙ＝７０．８μｍ、十点平均粗さ＝４１．３μｍとし、窒化により耐摩耗処理を行った。回転子３１４の周速を９０ｍ／ｓ、回転子３１４と固定子３１０の間隙を１．３ｍｍとして粉砕した。この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３１℃であった。得られた比較磁性トナー（ｖｉ）の物性値を表１４及び表１５に示し、比較磁性トナー（ｖｉ）の円形度と平均粒子径の関係を図２６に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６３】
比較例７
表１４に記載の処方で比較磁性トナー（ｖｉｉ）を作製した。粉砕工程は衝突式気流粉砕を用いた微粉砕機で粉砕し、得られた微粉砕粉末をコアンダ効果を利用した多分割分級機を用いて分級した。得られた比較磁性トナー（ｖｉｉ）の物性値を表１４及び表１５に示し、比較磁性トナー（ｖｉｉ）の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６４】
比較例８
表１４に記載の処方で比較磁性トナー（ｖｉｉｉ）を作製した。粉砕工程は衝突式気流粉砕を用いた微粉砕機で粉砕し、得られた微粉砕粉末をコアンダ効果を利用した多分割分級機を用いて分級し、分級後にハイブリタイザーにより粒子の形状及び表面性を改質した。得られた比較磁性トナー（ｖｉｉｉ）の物性値を表１４及び表１５に示し、比較磁性トナー（ｖｉｉｉ）の円形度と平均粒子径の関係を図２５に示す。また、実施例２１と同様の試験をした結果を表１６〜１９に示す。
【０３６５】
【表１４】

【０３６６】
【表１５】

【０３６７】
【表１６】

【０３６８】
【表１７】

【０３６９】
【表１８】

【０３７０】
【表１９】

【０３７１】
【発明の効果】
本発明によれば、特定の磁性酸化鉄の遊離数をもつトナーによって定着器の構成に関わらず定着器部材への付着を防止し、高湿下及び低湿下で使用しても高い画像品質が安定して得られ、経時において画像欠陥を生じず、さらに定着性を損なうことなく転写効率が向上できる。
【図面の簡単な説明】
【図１】本発明のトナーの製造方法の一例を説明する為のフローチャートである。
【図２】本発明のトナーの製造方法の一例を実施する為の装置システムの一具体例を示す概略図である。
【図３】本発明のトナーの粉砕工程において使用される一例の機械式粉砕機の概略断面図である。
【図４】図３におけるＤ−Ｄ’面での概略的断面図である。
【図５】図３に示す回転子の斜視図である。
【図６】本発明のトナーの分級工程に用いられる多分割気流式分級装置の概略断面図である。
【図７】従来の製造方法を説明する為のフローチャートである。
【図８】従来の製造方法を示すシステム図である。
【図９】従来の衝突式気流粉砕機の概略断面図である。
【図１０】従来の第２分級手段に用いられる多分割気流式分級装置の概略断面図である。
【図１１】本発明の磁性トナーを用いて画像形成を行うのに好適な画像形成装置の一例を示す概略図である。
【図１２】好適な画像形成装置の一例を示す概略図である。
【図１３】好適な画像形成装置の他の例を示す概略図である。
【図１４】転写装置の概略を示した図である。
【図１５】帯電ローラーの概略を示した図である。
【図１６】本発明のプロセスカートリッジの一例を示す説明図である。
【図１７】本発明の弾性ブレードを用いたプロセスカートリッジの一例を示す説明図である。
【図１８】本発明の実施例において用いられる注入帯電工程を有するプロセスカートリッジの一例を示す説明図である。
【図１９】トナーの帯電量測定に用いられる装置の説明図である。
【図２０】円形度と平均粒子径の関係を説明するための図である。
【図２１】円形度と平均粒子径の関係を説明するための図である。
【図２２】重量平均径Ｘとピーク粒度に対する半値幅Ｙの関係を説明するための図である。
【図２３】重量平均径Ｘとピーク粒度に対する半値幅Ｙの関係表す粒度分布のデータである。
【図２４】本発明の実施例において用いた添混合時の撹拌翼の説明図である。
【図２５】円形度と平均粒子径の関係を説明するための図である。
【図２６】円形度と平均粒子径の関係を説明するための図である。
【符号の説明】
１ 多分割分級機
２ 第２定量供給機
３ 振動フィーダー
４，５，６ 補集サイクロン
１１，１２，１３ 排出口
１１ａ，１２ａ，１３ａ 排出導管
１４，１５ 入気管
１６ 原料供給ノズル
１７，１８ 分級エッジ
１９ 入気エッジ
２０ 第１気体導入調節手段
２１ 第２気体導入調節手段
２２，２３ 側壁
２４，２５ 分級エッジブロック
２６ コアンダブロック
２７ 左部ブロック
２８，２９ 静圧計
３０ 分級域
３２ 分級室
４０ 原料供給口
４１ 高圧エアーノズル
４２ 原料粉体導入ノズル
１２２ 第１分級機
１２３ 補集サイクロン
１２４ 第２定量供給機
１２５ 振動フィーダー
１２７ 多分割分級機（第２分級機）
１２８ 気流式粉砕機
１２９，１３０，１３１ 補集サイクロン
１３５ インジェクションフィーダー
１４１，１４２ 側壁
１４３，１４４ 分級エッジブロック
１４５ コアンダブロック
１４６，１４７ 分級エッジ
１４８，１４９ 原料供給管
１５０ 分級室上部壁
１５１ 入気エッジ
１５３，１５３ 入気管
１５４，１５５ 気体導入調節手段
１５６，１５７ 静圧計
１５８，１５９，１６０ 排出口
１６１ 高圧気体供給ノズル
１６２ 加速管
１６３ 加速管出口
１６４ 衝突部材
１６５ 原料供給口
１６６ 衝突面
１６７ 粉砕物排出口
２１２ 渦巻室
２１９ パイプ
２２０ ディストリビュータ
２２２ バグフィルター
２２４ 吸引フィルター
２２９ 補集サイクロン
３０１ 機械式粉砕機
３０２ 粉体排出口
３１０ 固定子
３１１ 粉体投入口
３１２ 回転軸
３１３ ケーシング
３１４ 回転子
３１５ 第１定量供給機
３１６ ジャケット
３１７ 冷却水供給口
３１８ 冷却水排出口
３２０ 後室
３２１ 冷風発生手段
３３１ 第３定量供給機
７０１ 潜像担持体（感光体）
７０２ 転写ローラー
７０２ａ 芯金
７０２ｂ 導電性弾性層
７０４ 現像スリーブ（現像剤担持体）
７０５ 露光
７０９ 現像器
７１１ 磁性ブレード
７２３ 定電圧電源
７４２ 帯電ローラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to electrophotography, an image forming method for developing an electrostatic image, toner used in a toner jet, an image forming method using the toner, and a process cartridge having the toner.
[0002]
[Prior art]
Conventionally, a number of methods have been known as electrophotographic methods as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-24748, and the like. In general, a photoconductive material is used to form an electrical latent image on a photoconductor by various means, and then the latent image is developed with toner to form a visible image. After transferring the toner to such a transfer material, the toner image is fixed on the transfer material by heat, pressure, and heat and pressure to obtain a copy or print. The toner that has not been transferred and remains on the photoreceptor is cleaned by various methods, and the above-described steps are repeated.
[0003]
JP-A-55-18656 proposes a jumping development method. This involves applying a very thin magnetic toner on the sleeve, tribocharging it, and then developing it very close to the electrostatic charge image. This method is excellent in that the magnetic toner is thinly coated on the sleeve to increase the chance of contact between the sleeve and the toner, and sufficient frictional charging is possible.
[0004]
However, the developing method using the insulating magnetic toner has unstable elements related to the insulating magnetic toner to be used. This is because a considerable amount of fine powdered magnetic material is mixed and dispersed in the insulating magnetic toner, and a part of the magnetic material is released from the toner particles or exposed on the surface. In addition, it affects the triboelectric chargeability, and as a result, causes fluctuation or deterioration of various characteristics such as development characteristics and durability of the magnetic toner. This is considered to be caused by the presence of magnetic fine particles having a relatively low resistance compared to the resin constituting the toner on the surface of the magnetic toner particles. Further, the chargeability of the toner has a great influence on development and transfer, and is closely related to the image quality. For this reason, a magnetic toner capable of stably obtaining a high charge amount is desired.
[0005]
Furthermore, in recent years, such an apparatus using electrophotography has begun to be used for a printer for output of a computer, a facsimile, etc., in addition to a copying machine for copying an original document. As a result, smaller, lighter, faster, and more reliable devices are being sought, and machines are becoming simpler in many ways. As a result, the performance required for the toner becomes higher, and if the improvement in the performance of the toner cannot be achieved, a better machine cannot be realized.
[0006]
In JP-A-7-230182 and JP-A-8-286421, proposals have been made to stabilize charging properties by externally adding magnetic powder. According to this method, a toner having a stable chargeability and a high cleaning property can be obtained. However, in a printer having a simpler configuration at a high speed required in recent years, there is a problem that adhesion to a contact charging member easily occurs. is there.
[0007]
Further, when the toner image is transferred onto the transfer material from the photoconductor, there is toner remaining without being transferred onto the photoconductor. In order to obtain a good toner image even if continuous copying or printing is performed, it is necessary to clean the residual toner on the photoreceptor. The collected residual toner is discarded or recycled after being put in a container or a collection box installed in the main body.
[0008]
As a waste tonerless system, a design with a recycling mechanism inside the main body is required. However, in order to achieve the multifunctional, high-speed and high-quality copy images of copiers, printers and facsimiles required in the market, a considerably large recycling system is required in the main unit, and the main unit itself It becomes large and goes against the miniaturization required in the market. The same applies to a method in which waste toner is stored in a container or a collection box installed in the main body, and a method in which the photosensitive member and the portion for collecting the waste toner are integrated.
[0009]
In order to cope with these, it is necessary to improve the transfer rate when the toner image is transferred onto the transfer material from the photoreceptor.
[0010]
In JP-A-9-26672, a transfer efficiency improver having an average particle size of 0.1 to 3 μm and a BET specific surface area of 50 to 300 m.²/ G hydrophobic silica fine powder is included to reduce the volume resistance of the toner, and a transfer efficiency improver forms a thin film layer on the photoreceptor to improve transfer efficiency. However, since the toner produced by the pulverization method generally has a wide particle size distribution, it is difficult to uniformly improve the transfer rate for all toner particles, and further improvement is required.
[0011]
As a method for improving the transfer efficiency, there is a method for bringing the shape of the toner close to a spherical shape. As a method therefor, toners produced by production methods such as spray granulation, solution dissolution, and polymerization are disclosed in JP-A-3-84558, JP-A-3-229268, JP-A-4-1766, and JP-A-4-102862. Has been. However, these toner manufactures not only require large-scale equipment, but also easily cause a problem of poor cleaning because the toner approaches the true sphere.
[0012]
In general, as a toner production method, a binder resin for fixing a toner to a transfer material, a colorant or magnetic substance for giving a color as a toner, a charge control agent for imparting a charge to toner particles, and the like are dry-type. After mixing, the mixture was melt-kneaded in a kneading apparatus such as a roll mill and an extruder, cooled and solidified, and then the kneaded product was refined by a pulverizing apparatus such as a jet airflow pulverizer and a mechanical collision pulverizer. There is a method in which finely pulverized material is introduced into an air classifier and classified to obtain toner particles, and a fluidizing agent or lubricant is externally added to the toner particles as necessary. In the case of a two-component developer, it is formed of a magnetic carrier and the toner.
[0013]
An example of a flow for obtaining toner particles is shown in FIG.
[0014]
The coarsely pulverized toner is continuously or sequentially supplied to the first classifying means, and the coarse powder mainly composed of the classified coarse particle group having a specified particle size or more is sent to the pulverizing means and pulverized, and then again the first classifying means. It is circulated in.
[0015]
Toner finely pulverized toner mainly comprising particles within a prescribed particle size range and particles having a prescribed particle size or less are sent to the second classifying means, and a medium powder mainly comprising particles having a prescribed particle size, The powder is classified into fine powder mainly composed of particles smaller than the specified particle size and coarse powder mainly composed of particles larger than the specified particle size.
[0016]
As the pulverizing means, various pulverizing apparatuses are used. For the pulverization of the toner pulverized product mainly including the binder resin, a collision-type airflow pulverizer using a jet airflow as shown in FIG. 8 is used.
[0017]
A collision-type airflow crusher using a high-pressure gas such as a jet stream transports the powder raw material by a jet stream and injects it from the exit of the acceleration tube, and the powder material is provided facing the opening surface of the exit of the acceleration tube. The powder raw material is crushed by the impact force of the collision member.
[0018]
For example, in the collision-type airflow crusher shown in FIG. 9, the collision member 164 is provided facing the outlet 163 of the acceleration tube 162 connected to the high-pressure gas supply nozzle 161, and the acceleration tube 162 is supplied by the high-pressure gas supplied to the acceleration tube 162. The powder raw material is sucked into the accelerating tube 162 from the powder raw material supply port 165 communicated in the middle, and the powder raw material is jetted together with the high-pressure gas to collide with the collision surface 166 of the collision member 164 and pulverized by the impact. Then, the pulverized product is discharged from the pulverized product discharge port 167.
[0019]
However, the collision type airflow pulverizer has a configuration in which the powder raw material is jetted together with the high-pressure gas to collide with the collision surface of the collision member, and pulverized by the impact, so the pulverized toner is irregular and angular. As a result, the release agent and the magnetic powder are easily dropped from the toner particles.
[0020]
Japanese Patent Application Laid-Open No. 2-87157 discloses a method of improving the transfer efficiency by modifying the shape and surface properties of toner produced by a pulverization method by mechanical impact (hybridizer). However, this method requires a further processing step after pulverization, so that the toner particle productivity and the surface of the toner particle are close to an uneven state, and improvement on the developing surface is required, which is not a preferable method.
[0021]
In addition, a large amount of air is required to produce a toner having a small particle diameter by the collision type airflow pulverization. Therefore, power consumption is extremely large, and there is a problem in terms of energy cost. In particular, in recent years, energy saving in toner manufacturing apparatuses has been demanded in order to cope with environmental problems.
[0022]
Various classifiers and methods have been proposed for classifying means. Among these, there are classifiers using rotating blades and classifiers having no moving parts. Among these, there are a fixed wall centrifugal classifier and an inertial force classifier as classifiers having no moving parts. A classifier using such inertial force is proposed in Japanese Patent Publication No. Sho 54-24745, Japanese Patent Publication No. 55-6433, and Japanese Patent Publication No. 63-101858.
[0023]
As shown in FIG. 10, these airflow classifiers eject powder together with airflow at high speed from a supply nozzle having an opening in a classification area of the classifier room, and into the Coanda block 145 in the classification room. The coarse powder, the medium powder, and the fine powder are separated by the centrifugal force of the curved airflow that flows along the edges, and the edges 146, 147 whose tips are thin are classified into the coarse powder, the medium powder, and the fine powder.
[0024]
In the classifier 127, the finely pulverized raw material is introduced from the raw material supply nozzle, and the powder particles flowing in the pyramid cylinders 148 and 149 tend to flow with a propulsive force straight in parallel with the tube wall. However, when the raw material is introduced from the upper part in the raw material supply nozzle, it is divided into an upper flow and a lower flow, the upper flow contains a lot of light fine powder, and the lower flow tends to contain a lot of heavy coarse powder, Since each particle flows independently, there is a limit in improving classification accuracy because different trajectories are drawn depending on the introduction site into the classifier, and coarse powder disturbs the trajectory of fine powder.
[0025]
In general, a toner is required to have many different properties, and in order to obtain the required properties, the raw materials used are often determined by the manufacturing method. In the toner classification process, the classified particles are required to have a sharp particle size distribution. In addition, it is desired to produce a high-quality toner stably and efficiently at a low cost.
[0026]
Furthermore, in recent years, toner particles are gradually moving toward finer dimensions in order to improve image quality in copying machines and printers. In general, as the substance becomes finer, the action of interparticle force increases, but the same applies to resins and toners, and the cohesiveness between particles increases as the size of the fine powder.
[0027]
In particular, when trying to obtain a toner having a sharp particle size distribution with a weight average diameter of 10 μm or less, the conventional apparatus and method cause a reduction in classification yield. Furthermore, when trying to obtain a toner having a sharp particle size distribution with a weight average diameter of 8 μm or less, the conventional apparatus and method not only cause a reduction in classification yield, but also contain a large amount of ultrafine powder. There is a tendency to end up.
[0028]
Even if a desired product having a precise particle size distribution can be obtained under the conventional method, the process becomes complicated, causing a reduction in classification yield, resulting in poor production efficiency and high cost. This tendency becomes more prominent as the predetermined particle size becomes smaller.
[0029]
Further, in a magnetic toner having a particle size smaller than the normal particle size, the amount of the magnetic material contained in the toner particle is increased to suppress fogging, and the released magnetic material is increased accordingly. For this reason, when dealing with higher speeds, the low-temperature fixability of the toner is lowered, and the developability tends to be more severely restricted than before.
[0030]
[Problems to be solved by the invention]
  The object of the present invention is to provide a dry process that solves the above problems.MagnetismTona-AndAnd providing an image forming method.
[0031]
  The object of the present invention is to provide a dry process that can maintain good developability even for fine particles.MagnetismTona-AndAnd providing an image forming method.
[0032]
  An object of the present invention is to provide a dry transfer system that generates little waste toner and has high transfer efficiency.MagnetismTona-AndAnd providing an image forming method.
[0033]
[Means for Solving the Problems]
  The present invention relates to magnetic toner particles having at least a binder resin, magnetic iron oxide particles and wax, and inorganic fine powderas well asIn the dry magnetic toner having hydrophobic inorganic fine powder,
  The magnetic toner particles are obtained by melt-kneading a mixture containing at least a binder resin, magnetic iron oxide particles and wax, cooling the kneaded product, coarsely pulverizing the cooled product, and obtaining the coarsely pulverized product with a mechanical pulverizer. Obtained by pulverizing with
  The inorganic fine powderas well asThe hydrophobic inorganic fine powder is used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the magnetic toner.
  The inorganic fine powder is strontium titanate, the hydrophobic inorganic fine powder is a hydrophobic silica fine powder,
  100 to 350 free magnetic iron oxide particles are present per 10,000 magnetic toner particles,
  The magnetic toner has a weight average particle diameter of 5 μm to 12 μm, and
  The circularity of the particles constituting the magnetic toner is the circularity measured by the following measurement method,
  Measuring method: [Method for measuring the circularity of particles constituting the magnetic toner: 0.1 to 0.5 ml of a surfactant as a dispersing agent is added to 100 to 150 ml of water from which impurities in the container have been previously removed, and then the magnetic toner is added. 0.1 to 0.5 g is added, and the suspension in which the magnetic toner is dispersed is irradiated with ultrasonic waves (50 kHz, 120 W) for 1 to 3 minutes, and the dispersion concentration is set to 1.2 to 2 million pieces / μl. Using a flow type particle image measuring apparatus, the circularity distribution of particles having a circle-equivalent diameter of 0.60 μm or more and less than 159.21 μm is measured. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the following circularity calculation formula. ]
  In the particles of 3 μm or more constituting the magnetic toner, 90% by number or more of particles having a circularity a of 0.900 or more obtained from the following formula (1) based on the number,
    Circularity a = L₀/ L (1)
[Where L₀Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image. ]
  and
  a) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (2):
    Cut rate Z ≦ 5.3 × X (2)
[However, the cut rate Z is expressed by the equation (3) when the particle concentration A (number / μl) of all measured particles and the measured particle concentration B (number / μl) of the equivalent circle diameter of 3 μm or more.
    Z = (1-B / A) × 100 (3)]
  In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (4);
  Number-based cumulative value Y ≧ exp5.51 × X of particles having a circularity of 0.950 or more^-0.645(4)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
  Or
  b) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (5):
    Cut rate Z> 5.3 × X (5)
  In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (6);
  Number-based cumulative value Y ≧ exp5.37 × X of particles having a circularity of 0.950 or more^-0.545(6)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
The present invention relates to a dry magnetic toner.
[0034]
  Furthermore, the present invention forms an electrostatic charge image on the electrostatic charge image carrier, and develops the electrostatic charge image with a dry magnetic toner held in the developing means to form a magnetic toner image.
  In an image forming method in which the formed magnetic toner image is transferred to a transfer material with or without an intermediate transfer member, and the magnetic toner image on the transfer material is fixed to the transfer material by heating and pressing fixing means. ,
  The magnetic toner includes magnetic toner particles having at least a binder resin, magnetic iron oxide particles and wax, and an inorganic fine powder.as well asA dry magnetic toner having hydrophobic inorganic fine powder,
  The magnetic toner particles are obtained by melt-kneading a mixture containing at least a binder resin, magnetic iron oxide particles and wax, cooling the kneaded product, coarsely pulverizing the cooled product, and obtaining the coarsely pulverized product with a mechanical pulverizer. Obtained by pulverizing with
  The inorganic fine powderas well asThe hydrophobic inorganic fine powder is used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the magnetic toner.
  The inorganic fine powder is strontium titanate, the hydrophobic inorganic fine powder is a hydrophobic silica fine powder,
  100 to 350 free magnetic iron oxide particles are present per 10,000 magnetic toner particles,
  The magnetic toner has a weight average particle diameter of 5 μm to 12 μm, and
  The circularity of the particles constituting the magnetic toner is the circularity measured by the following measurement method,
  Measuring method: [Method for measuring the circularity of particles constituting the magnetic toner: 0.1 to 0.5 ml of a surfactant as a dispersing agent is added to 100 to 150 ml of water from which impurities in the container have been previously removed, and then the magnetic toner is added. 0.1 to 0.5 g is added, and the suspension in which the magnetic toner is dispersed is irradiated with ultrasonic waves (50 kHz, 120 W) for 1 to 3 minutes, and the dispersion concentration is set to 1.2 to 2 million pieces / μl. Using a flow type particle image measuring apparatus, the circularity distribution of particles having a circle-equivalent diameter of 0.60 μm or more and less than 159.21 μm is measured. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the following circularity calculation formula. ]
  In the particles of 3 μm or more constituting the magnetic toner, 90% by number or more of particles having a circularity a of 0.900 or more obtained from the following formula (1) based on the number,
    Circularity a = L₀/ L (1)
[Where L₀Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image. ]
  and
  a) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (2):
    Cut rate Z ≦ 5.3 × X (2)
[However, the cut rate Z is expressed by the equation (3) when the particle concentration A (number / μl) of all measured particles and the measured particle concentration B (number / μl) of the equivalent circle diameter of 3 μm or more.
    Z = (1-B / A) × 100 (3)]
  In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (4);
  Number-based cumulative value Y ≧ exp5.51 × X of particles having a circularity of 0.950 or more^-0.645(4)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
  Or
  b) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (5):
    Cut rate Z> 5.3 × X (5)
  In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (6);
  Number-based cumulative value Y ≧ exp5.37 × X of particles having a circularity of 0.950 or more^-0.545(6)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
The present invention relates to an image forming method.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors proceeded with studies on the amount, shape, and toner constituent material of the free magnetic material in the toner produced by the pulverization method, and in terms of the amount of free magnetic material in the toner, as well as the shape, transferability and developability. I found a close relationship.
[0037]
It has been found that the toner of the present invention improves the transfer efficiency without impairing the fixability, stably obtains high image quality even when used under high and low humidity, and does not cause image defects over time. It was.
[0038]
  The dry toner of the present invention contains at least a binder resin and magnetic iron oxide, and particles having free iron element are 100 to 350 per 10,000 toner particles.PiecesThe number is preferably 100 to 300, preferably 120 to 250, and more preferably 120 to 200.
[0039]
When the number of particles containing the released iron element is more than 300, toner charge leakage is likely to occur through the released particles, and as a result, the charge amount of the toner is reduced. In addition, toner with a low charge amount causes an increase in fog and has a low transfer efficiency and causes a charging failure, which adversely affects developability. Further, the adhesion of the toner to the toner carrying member is increased, the triboelectric charge and the charge imparting ability are hindered to cause a charging failure, and as a result, the developability is adversely affected. On the other hand, when the number of particles having free iron element is less than 100, it indicates that the magnetic iron oxide particles in the toner are not substantially free. Although toner with almost no separation has a high charge amount, charge-up is likely to occur when a large number of images are printed with a high-speed machine, especially when a large number of images are printed under low temperature and low humidity. Is prone to decline. By controlling the number of particles containing free iron elements to be in the range of 100 to 300, a toner having easy charge control, uniform charge and stable durability of charge can be obtained.
[0040]
Next, a method for measuring the number of particles having free iron element in the present invention will be described.
[0041]
Here, “the number of particles having a free iron element” is measured by a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation), and the particle analyzer is described on pages 65-68 of the paper of Japan Hardcopy97. Measure on the principle of Specifically, the device is a device that introduces toner fine particles one by one into the plasma, and knows the element of the luminescent material, the number of particles, and the particle size of the particles from the emission spectrum of the fine particles. For example, consider the case where toner particles are introduced into the plasma. When the toner particles are introduced into the plasma, light emission of carbon, which is a constituent element of the binder resin, and light emission of iron atoms in the magnetic iron oxide particles with respect to one toner particle. Are observed respectively. Since one light emission is obtained for each toner particle, the number of toner particles can be obtained from the number of times of light emission. At that time, iron atoms emitted within 2.6 msec from the emission of carbon atoms were simultaneously emitted iron atoms, and subsequent iron atoms were emitted only from iron atoms.
[0042]
Since the toner of the present invention contains magnetic iron oxide particles, the fact that carbon atoms and iron atoms emit light at the same time means that the magnetic iron oxide particles are dispersed in the toner particles. In terms of light emission, it can be said that the magnetic iron oxide particles are released from the toner particles. As a specific method, a toner sample conditioned by being left overnight in an environment of a temperature of 23 ° C. and a humidity of 60% is measured using helium gas containing 0.1% oxygen in the environment. Carbon atom is measured in channel 1 (measurement wavelength 247.86 nm, K factor is the recommended value), and iron atom is measured in channel 2 (measurement wavelength is 239.56 nm, K factor is 3.3764). Sampling is performed so that the number of emitted light becomes 1000 to 1400, and scanning is repeated until the total number of emitted light of carbon atoms reaches 10,000 or more, and the number of emitted light is integrated. At this time, it is important that the particle size distribution curve having the luminescence number of the element on the vertical axis and the cube root voltage representing the particle diameter of the particle on the horizontal axis has one maximum, and that there is no valley. . Then, by counting the number of light emission of only iron atoms at that time, the number of particles having a free iron element was obtained. At this time, the noise cut level is 1.50V. In addition, the azo-based iron compound that is a charge control agent contained in the toner may contain iron atoms, but since these control agents are organometallic compounds, light emission only from the iron atoms is not possible. .
[0043]
Further, although the charge control agent may be released, it is negligible because it is very small at 1 to 3% compared to the added amount of the binder resin and magnetic iron oxide particles in the toner particles. Therefore, it can be considered that the light emission of carbon atoms and iron atoms measured by this apparatus is only light emission of the binder resin and magnetic iron oxide particles.
[0044]
In addition, the toner of the present invention can be controlled, for example, by a method described later, whereby the circularity of toner particles of 3 μm or more and the number of free magnetic iron oxide particles can be controlled in the range of 100 to 300.
[0045]
The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of particles, and in the present invention, measurement is performed using a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, The circularity of the measured particles is obtained by the following equation (1), and the value obtained by dividing the total circularity of all particles measured by the total number of particles as defined by the following equation (8) is defined as the average circularity. To do.
[0046]
Circularity a = L₀/ L (1)
[Where L₀Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image. ]
[0047]
[Expression 1]

[0048]

[0049]
[Expression 2]

[0050]
The circularity used in the present invention is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere. The more complicated the surface shape, the smaller the circularity. Further, the circularity distribution SD in the present invention is an index of variation, and the smaller the numerical value, the smaller the variation in toner shape.
[0051]
“FPIA-1000”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation. .4 to 1.0 are divided into 61 classes, and a calculation method is used in which the average circularity and the circularity standard deviation are calculated using the center value and frequency of the division points. However, the error of the average circularity and the circularity standard deviation calculated by the calculation formula using each value of the average circularity and the circularity standard deviation calculated by this calculation method and the circularity of each particle described above is In the present invention, the circularity of each particle described above is directly set for the reason of handling data such as shortening the calculation time and simplifying the calculation formula. Such a calculation method that is partially changed using the concept of the calculation formula to be used may be used.
[0052]
Conventionally, it has been known that the shape of the toner affects various properties of the toner, but the present inventors have found that the shape of the toner of 3 μm or more and the amount of free magnetic iron oxide particles are transferred by various studies. The present inventors have found that development properties are greatly affected. Further, the present inventors have also found that if a group of particles having an equivalent circle diameter of less than 3 μm exceeds a certain amount, transferability and developability are deteriorated. Clearly, when the amount of fine powder of toner having a particle diameter of less than 3 μm or an external additive having a particle diameter of less than 3 μm exceeds a certain level, it is difficult to obtain desired performance unless the circularity of the toner having a particle diameter of 3 μm or more is increased. became.
[0053]
Therefore, in the present invention, the degree of circularity of a particle group having an equivalent-circle diameter of 3 μm or more is important for expressing the effects of the present invention. In order to exhibit the effect of the circularity of the toner particles more effectively, it is necessary to control the circularity of the toner particles of 3 μm or more by the amount of fine powder of 3 μm or less as follows.
[0054]
By controlling the circularity of toner particles of 3 μm or more by the amount of fine powder of 3 μm or less, a toner having excellent transferability and developability can be obtained.
[0055]
In the measurement of the circularity in FPIA-1000, the smaller the particle diameter is, the closer the particle image is to a point, so that the circularity tends to increase. For this reason, when a large amount of particles having a small particle diameter are present in the toner, the circularity of the toner increases. On the other hand, when only a small amount of particles having a small particle size is present in the toner, the circularity of the toner becomes small. Therefore, as calculated by the following equation (3), the cut rate Z is obtained by subtracting the ratio of the particle concentration of the particle group having a circle equivalent diameter of 3 μm or more to the particle concentration of all the measured particles from 100%. And the weight average particle size X are divided into two cases of the formula (2) or the formula (5), and in each case, the circularity and the weight average of the toner necessary to satisfy the desired performance The relationship with the particle diameter was derived as shown in Formula (4) or Formula (6).
[0056]
Cut rate Z = (1−B / A) × 100 (3)
[In the formula, A represents the particle concentration of all the measured particles, and B represents the particle concentration of a particle group having an equivalent circle diameter of 3 μm or more.
[0057]
In a toner containing a small amount of particles less than 3 μm, the cumulative value Y based on the number of particles having a circularity of 0.950 or more in the particles of 3 μm or more is exp 5.51 × X with respect to the weight average diameter X.^-0.645(≈247.151 × X^-0.645However, in a toner containing a large amount of particles of less than 3 μm, the cumulative value Y based on the number of particles having a circularity of 0.950 or more in the particles of 3 μm or more is equal to the weight average diameter X. On the other hand, larger exp5.37 × X^-0.545It is necessary to do more.
[0058]
  In the toner of the present invention, particles having a circularity a of 0.900 or more in particles of 3 μm or more of the toner are 90 in terms of the cumulative number based on the number.Number%) And particles having a circularity a of 0.950 or more are cumulative values based on the number, and a) the relationship between the cut rate Z and the toner weight average diameter X is the cut rate Z ≦ 5.3 × X (preferably When satisfying the equation of 0 <cut rate Z ≦ 5.3 × X), the number reference cumulative value Y ≧ exp5.51 × X^-0.645Is preferably satisfied.
[0059]
Alternatively, the toner of the present invention contains 90% or more of particles having a circularity a of 0.900 or more in particles of 3 μm or more of the toner in terms of the number-based cumulative value, and particles having a circularity a of 0.950 or more. B) When the relationship between the cut rate Z and the toner weight average diameter X satisfies the formula of cut rate Z> 5.3 × X (preferably 95 ≧ cut rate Z> 5.3 × X). ,
Number-based cumulative value Y ≧ exp5.37 × X^-0.545Is preferably satisfied.
[However, the cut rate Z is the particle concentration A (number / μl) of all measured particles measured with a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, and the measured particle concentration B (number of particles with an equivalent circle diameter of 3 μm or more) / Μl), it is expressed by equation (3),
Z = (1-B / A) × 100 (3)
The toner weight average particle diameter X is 5.0 to 12.0 μm. ]
[0060]
When the toner has such a circularity, the toner can be easily charged and can achieve uniform charge and durable charge stability. Further, it has been found that the transfer efficiency is increased when the circularity is as described above. This is because in the case of the toner having the circularity as described above, the contact area between the toner particles and the photoconductor is reduced, and the adhesion force of the toner particles to the photoconductor due to van der Waals force is reduced. It is believed that there is. Furthermore, compared with toner pulverized by a conventional collision type airflow pulverizer, such toner particles have a small specific surface area, so the contact area between the toner particles is reduced and the bulk density of the toner powder becomes dense. In addition, the heat conduction during fixing can be improved, and the effect of improving the fixing property can also be obtained.
[0061]
Further, when the presence of particles having a circularity a of 0.900 or more in the particles of 3 μm or more of the toner is less than 90% in terms of the number-based cumulative value, the magnetic iron oxide particles in which the toner charge leakage is released are removed. As a result, even if the amount of free magnetic iron oxide particles is controlled, the charge amount of the toner may decrease as a result. Further, the contact area between the toner particles and the photoconductor is increased, and the adhesion force of the toner particles to the photoconductor is increased, so that it is difficult to obtain sufficient transfer efficiency.
[0062]
Further, particles having a circularity a of 0.950 or more among the particles of 3 μm or more of the toner are cumulative values based on the number, and a) The relationship between the cut rate Z and the toner weight average diameter X is cut rate Z ≦ 5.3 ×. X (preferably 0 <cut rate Z ≦ 5.3 × X) is satisfied,
Number-based cumulative value Y ≧ exp5.51 × X^-0.645Is not satisfied, that is,
Number reference cumulative value Y <exp5.51 × X^-0.645Or particles having a circularity a of 0.950 or more in the particles of 3 μm or more of the toner are cumulative values based on the number, and the relationship between b> cut rate Z and toner weight average diameter X is cut Satisfying the formula of rate Z> 5.3 × X (preferably 95 ≧ cut rate Z> 5.3 × X),
Number-based cumulative value Y ≧ exp5.37 × X^-0.545If you do not satisfy
Number-based cumulative value Y <exp5.37 × X^-0.545In the case of satisfying the above, not only sufficient transfer efficiency cannot be obtained, but also the fluidity of the toner tends to be lowered, and furthermore, the desired fixing performance is difficult to obtain.
[0063]
Further, when a toner having a specific circularity is produced, the weight average diameter is preferably 5 to 12 μm.
[0064]
More preferably, the toner has a weight average diameter of 5 to 10 μm, particles having a particle size of 4.0 μm or less are 40% by number or less, and particles having a particle size of 10.1 μm or more are 25% by volume or less. Good.
[0065]
When obtaining a toner having a weight average diameter exceeding 12 μm, it is possible to cope with the particle size by reducing the load in the pulverizer as much as possible or increasing the processing amount, but the shape becomes square and desired. It is difficult to achieve a desired circularity, and it is difficult to obtain a desired circularity distribution.
[0066]
When obtaining a toner having a weight average diameter of less than 5 μm, it can be dealt with by increasing the load in the pulverizer or by reducing the processing amount extremely, but the shape approximates a sphere and has a desired circularity. It is difficult not only to obtain a desired circularity distribution but also to prevent generation of fine powder and ultrafine powder.
[0067]
The toner of the present invention contains 90% or more of particles having a circularity a of 0.900 or more in particles of 3 μm or more of the toner in terms of the number-based cumulative value, and the number of particles having a circularity a of 0.950 or more. A) The relationship between the cut rate Z and the toner weight average diameter X satisfies the formula of cut rate Z ≦ 5.3 × X (preferably 0 <cut rate Z ≦ 5.3 × X).
Number-based cumulative value Y ≧ exp5.51 × X^-0.645More preferably, more preferably
Number reference cumulative value exp4.85 × X^-0.187≧ Y <exp5.51 × X^-0.645It is.
Alternatively, in the toner of the present invention, particles having a circularity a of 0.950 or more in the particles of 3 μm or more of the toner are cumulative values based on the number, and b) the relationship between the cut rate Z and the toner weight average diameter X is the cut rate Z > 5.3 × X (preferably 95 ≧ cut rate Z> 5.3 × X)
Number reference cumulative value exp4.85 × X^-0.187≧ Y ≧ exp5.37 × X^-0.545It is.
When the toner has such a circularity, it is possible to obtain a toner that is easy to control the charge, uniform in charge, and durable in charge stability. Further, when the circularity is as described above, the transfer efficiency can be increased. This is because in the case of the toner having the circularity as described above, the contact area between the toner particles and the photoconductor is reduced, and the adhesion force of the toner particles to the photoconductor due to van der Waals force or the like is reduced. it is conceivable that. Furthermore, since the specific surface area of the toner particles is reduced compared to the toner pulverized by the conventional collision type airflow pulverizer, the contact area between the toner particles is reduced and the bulk density of the toner powder becomes dense. In addition, the heat conduction during fixing can be improved, and the effect of improving the fixing property can also be obtained.
[0068]
Even when a toner having a particle size of 4.0 μm or less that exceeds 40% by number can be dealt with by increasing the load in the pulverizer or by reducing the processing amount extremely, the shape is spherical. It is difficult to approximate to a desired circularity, and it is difficult to obtain a desired circularity distribution.
[0069]
When obtaining a toner in which particles having a particle size of 10.1 μm or more exceed 25% by volume, it is possible to cope with the particle size by reducing the load in the pulverizer as much as possible or increasing the processing amount, but the shape is angular. Therefore, it is difficult to obtain a desired circularity, and it is difficult to obtain a desired circularity distribution.
[0070]
The circularity standard deviation SD can also be used as one standard for the variation of particles having such circularity. In the present invention, there is no problem if the circularity standard deviation SD is 0.030 to 0.045.
[0071]
As a specific measurement method, 0.1 to 0.5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impurities in the container have been removed in advance, and a measurement sample is further added. Add about 0.1-0.5g. The suspension in which the sample is dispersed is irradiated with ultrasonic waves (50 kHz, 120 W) for 1 to 3 minutes, the dispersion concentration is set to 1.2 to 2 million pieces / μl, and the flow type particle image measurement apparatus is used. The circularity distribution of particles having an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm is measured. By setting the dispersion concentration to 1.2 to 2 million particles / μl, it is possible to maintain a particle concentration sufficient to maintain the accuracy of the apparatus even when the cut rate increases.
[0072]
The outline of the measurement is described in the catalog (June 1995 edition) of FPIA-1000 issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring apparatus, and JP-A-8-136439. The measurement method will be described below.
[0073]
The sample dispersion is passed through a flow path (expanded along the flow direction) of a flat and flat flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be opposite to each other so as to form an optical path that passes through the thickness of the flow cell. While the sample dispersion is flowing, strobe light is irradiated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a certain range parallel to the flow cell. Photographed as a two-dimensional image. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above circularity calculation formula.
[0074]
Next, the binder resin used for the toner of the present invention will be described.
[0075]
The acid value of the binder resin used in the present invention is preferably 1 to 100 mgKOH / g, more preferably 1 to 50 mgKOH / g, and particularly preferably 2 to 40 mgKOH / g.
[0076]
Without such an acid value range, the dispersion state of the toner raw materials, particularly the magnetic iron oxide particles, deteriorates in the kneading step at the time of toner production, and the free magnetic iron oxide particles tend to increase in the pulverization step.
[0077]
When the acid value of the binder resin is less than 1 mgKOH / g, the chargeability of the toner particles is lowered, and developability and durability stability are lowered. On the other hand, when it exceeds 100 mgKOH / g, the hygroscopicity of the binder resin becomes strong, the image density tends to decrease, and the fog tends to increase.
[0078]
In the present invention, the acid value of the binder resin is determined by the following method.
[0079]
Measurement of acid value
Basic operation conforms to JIS K-0070.
1) The binder resin pulverized product 0.5 to 2.0 (g) is precisely weighed to obtain the weight W (g) of the binder resin.
2) A sample is put into a 300 (ml) beaker, and a mixed solution 150 (ml) of toluene / ethanol (4/1) is added and dissolved.
3) Using a 0.1N KOH methanol solution, titration is performed using a potentiometric titrator (for example, using a potentiometric titrator AT-400 (winworkstation) manufactured by Kyoto Electronics Co., Ltd. and an ABP-410 electric burette. All automatic titrations are available.)
4) The amount of KOH solution used at this time is S (ml), and at the same time, a blank is measured, and the amount of KOH solution used at this time is B (ml).
5) Calculate the acid value according to the following formula. f is a factor of KOH.
[0080]
Acid value (mgKOH / g) = ((SB) × f × 5.61) / W
[0081]
As the binder resin, a vinyl polymer having a carboxyl group or an acid anhydride group, a polyester resin, or the like can be used.
[0082]
Examples of the monomer for producing a vinyl polymer used as a binder resin include the following.
[0083]
For example, unsaturated dibasic acids such as maleic acid, citraconic acid, dimethylmaleic acid, itaconic acid, alkenyl succinic acid, fumaric acid, metaconic acid, dimethylfumaric acid and their anhydrides. And monoesters of the above unsaturated dibasic acids. Also, α, β-unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid and cinnamic acid and their anhydrides; the α, β-unsaturated dibasic acid and the α, β-unsaturated monoacid Anhydrides and anhydrides of the above unsaturated acids and lower fatty acids. Alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid and anhydrides thereof and monoesters thereof. Among these, maleic acid, maleic acid half ester, and maleic anhydride are particularly preferably used as the monomer for obtaining the binder resin of the present invention.
[0084]
Furthermore, the following are mentioned as a comonomer for producing | generating a vinyl polymer.
[0085]
For example, styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl Styrene derivatives such as styrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; unsaturated polyenes such as butadiene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; Vinyl ethers such as vinyl acetate, vinyl propionate and vinyl benzoate. Tells; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, Α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate , Acrylic acid esters such as dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether, vinyl ethyl Vinyl ethers such as ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, and N-vinyl pyrrolidone. Vinyl compounds; vinyl naphthalene; acrylic acid derivatives or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; esters of the aforementioned α, β-unsaturated acids and diesters of dibasic acids. These vinyl monomers are used alone or in combination of two or more.
[0086]
Among these, a combination of monomers that becomes a styrene copolymer or a styrene-acrylic copolymer is preferable.
[0087]
As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used.
[0088]
The binder resin used in the present invention may be a polymer crosslinked with a crosslinkable monomer as exemplified below if necessary.
[0089]
Aromatic divinyl compounds (eg, divinylbenzene, divinylnaphthalene, etc.); diacrylate compounds linked by alkyl chains (eg, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate) 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); di-linked by an alkyl chain containing an ether bond Acrylate compounds (eg, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 00 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); diacrylate compounds linked by a chain containing an aromatic group and an ether bond (for example, , Polyoxyethylene (2) -2,2-bis (4-hydroxydiphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxydiphenyl) propane diacrylate and the above compounds A compound obtained by replacing acrylate with methacrylate); polyester-type diacrylate compounds (for example, trade name MANDA (Nippon Kayaku)). Polyfunctional cross-linking agents include pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of the above compounds replaced with methacrylate; Examples include lucyanurate and triallyl trimellitate.
[0090]
These crosslinking agents are preferably used in an amount of about 0.01 to 5 parts by mass (more preferably about 0.03 to 3 parts by mass) with respect to 100 parts by mass of other monomer components.
[0091]
Examples of the polymerization agent and the polymerization initiator for polymerizing the vinyl monomer include benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4, Organics such as 4-di (t-butylperoxy) valerate, dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide Peroxides; azo and diazo compounds such as azobisisobutyronitrile and diazoaminoazobenzene.
[0092]
As a method for synthesizing the binder resin, a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be used.
[0093]
The toner of the present invention preferably has a main peak in a region having a molecular weight of 2,000 to 25,000, more preferably a region having a molecular weight of 5,000 to 20,000. The main peak is good. Further, a toner in which the soluble component of THF is 50 to 90% of a component having a molecular weight of 100,000 or less is preferable. When the molecular weight of the main peak is less than 2000, the toner cannot have an appropriate elasticity, so that the fixability is improved, but the durability as a toner is lowered. Accordingly, the magnetic iron oxide particles are likely to be missing from the toner particles as the second half of the durability is reached, and as a result, the developability tends to be lowered in the second half of the durability. Further, when the molecular weight of the main peak is less than 2000, the storage stability of the toner is also lowered. When the molecular weight of the main peak is larger than 25,000, the fixing property is lowered.
[0094]
As described above, in the molecular weight distribution by GPC of the THF soluble part of the toner, the toner having such a peak maintains a good balance of fixing property, offset resistance and storage stability.
[0095]
In order to produce a toner having a desired molecular weight distribution, the binder resin preferably has a main peak in a region having a molecular weight of 2,000 to 25,000.
[0096]
If the molecular weight distribution does not have such a peak, the resin cannot have an appropriate elasticity, so that kneading share cannot be applied at the time of melt kneading at the time of toner production, and the dispersibility of the raw material is lowered, and in the grinding process In addition, the magnetic iron oxide particles are easily released from the toner particles. Furthermore, since the dispersibility of the raw material is lowered, both the fixability and the durability stability are lowered.
[0097]
In the present invention, the molecular weight distribution by GPC using the THF soluble component of the toner and binder resin as a solvent is measured under the following conditions.
[0098]
The column is stabilized in a heat chamber at 40 ° C., THF is flowed through the column at this temperature as a solvent at a flow rate of 1 ml / min, and about 100 μl of the THF sample solution is injected and measured. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the body value and the count value of a calibration curve prepared with several types of monodisperse polystyrene standard samples. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 10 manufactured by Tosoh Corporation or Showa Denko KK is 10²-10⁷It is appropriate to use a standard polystyrene sample of about 10 points. As a detector, an RI (refractive index) detector is used. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. (H_XL), G2000H (H_XL), G3000H (H_XL), G4000H (H_XL), G5000H (H_XL), G6000H (H_XL), G7000H (H_XL), A combination of TSKgull column.
[0099]
The sample is prepared as follows.
[0100]
Place the sample in THF and let stand for several hours, then shake well and mix well with THF (until the sample is no longer united) and let stand for more than 12 hours. At that time, the standing time in THF should be 24 hours or more. After that, a sample processed filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation) can be used) is used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0101]
The toner has a glass transition temperature (Tg) of 45 to 75 ° C., preferably 50 to 70 ° C. from the viewpoint of storage stability of the toner. When the toner Tg is lower than 45 ° C., the toner deteriorates in a high temperature atmosphere. It is easy to cause an offset at the time of fixing. Further, when the Tg of the toner exceeds 75 ° C., the fixability tends to be lowered.
[0102]
Next, magnetic iron oxide particles will be described.
[0103]
Examples of the magnetic iron oxide particles used in the present invention include magnetic iron oxides such as magnetite, maghemite and ferrite containing iron or oxides or hydroxides of different elements on the surface thereof, and mixtures thereof. Thus, by containing an oxide or hydroxide on the surface of the magnetic iron oxide particles, preferably an oxide or hydroxide of a non-ferrous element, the resin is familiar to the binder resin and has a very dispersibility. As a result, free magnetic iron oxide particles are less likely to be produced in the pulverization process during the production of toner particles. As a result, transfer efficiency is improved, and high image quality is stably obtained even when used under high and low humidity. Thus, a toner that does not cause image defects over time can be obtained, and also contributes to charge control of free magnetic iron oxide particles. Among them, lithium, beryllium, boron, magnesium, aluminum, silicon, phosphorus, germanium, titanium, zirconium, tin, lead, zinc, calcium, barium, scandium, vanadium, chromium, manganese, cobalt, copper, nickel, gallium, cadmium, indium Magnetic properties containing oxides or hydroxides of at least one element selected from silver, palladium, gold, mercury, platinum, tungsten, molybdenum, niobium, osmium, strontium, yttrium, technetium, ruthenium, rhodium, and bismuth Iron oxide particles are preferred.
[0104]
In the present invention, the abundance of iron on the surface of the magnetic iron oxide particles or oxides or hydroxides of different elements can be expressed by the degree of hydrophobicity of the magnetic iron oxide particles, and the magnetic iron oxide having a degree of hydrophobicity of 20% or less. In the case of particles, it can be said that iron or an oxide or hydroxide of a different element that can maintain the above performance exists on the surface.
[0105]
The degree of hydrophobicity of the magnetic iron oxide particles in the present invention is measured by the following method.
[0106]
The degree of hydrophobicity of the magnetic iron oxide particles was measured by a methanol titration test. Hydrophobization degree measurement using methanol is performed as follows. Add 0.1 g of magnetic iron oxide particles to a 250 ml beaker containing 50 ml of distilled water. Thereafter, methanol is supplied into the liquid from the bottom of the liquid at a rate of 1.3 ml / min. At this time, it is preferable to supply the solution with gentle stirring. When the sedimentation of magnetic iron oxide particles ends, the suspended matter of magnetic iron oxide particles is no longer confirmed on the liquid surface, and the degree of hydrophobicity is the volume of methanol in the methanol and water mixture when the sedimentation end time is reached. Expressed as a percentage.
[0107]
If these magnetic iron oxide particles have a uniform particle size distribution, the dispersibility in the binder resin is improved and the chargeability of the toner can be stabilized. In recent years, the toner particle size has been reduced, and even when the weight average particle size is 10 μm or less, charging uniformity is promoted, toner aggregation is reduced, image density is improved, and fog is improved. , Developability is improved. In particular, the effect is remarkable in a toner having a weight average particle diameter of 6.0 μm or less, and an extremely fine image can be obtained. A weight average particle diameter of 5 μm or more is preferable because a sufficient image density can be obtained.
[0108]
The content of these different elements is preferably 0.05 to 10% by mass based on the iron element of the magnetic iron oxide particles. More preferably, it is 0.1-7 mass%, Most preferably, it is 0.2-5 mass%, Furthermore, it is 0.3-4 mass%. If it is less than 0.05% by mass, the effect of containing these elements cannot be obtained, and good dispersibility and charging uniformity cannot be obtained. On the other hand, if it exceeds 10% by mass, the discharge of charge increases, resulting in insufficient charging, and the image density may be lowered or fog may increase.
[0109]
In addition, in the content distribution of these different elements, it is preferable that many exist in the vicinity of the surface of the magnetic particles. For example, the ratio (B / A) × 100 of the content B of the different elements present in the magnetic iron oxide particles up to 20% by mass and the total content A of the different elements of the magnetic iron oxide particles is 100 It is preferable that it is 40% or more. Furthermore, 40 to 80% is preferable, and 60 to 80% is particularly preferable. By increasing the surface abundance, the dispersion effect and the electric diffusion effect can be further improved. Further, the amount contained in the toner particles is preferably 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.
[0110]
In the toner of the present invention, the content of silicon element in the magnetic iron oxide particles is 0.4 to 2.0% by mass (more preferably 0.5 to 0.9% by mass) based on the iron element. In addition, the Fe / Si atomic ratio on the outermost surface of the magnetic iron oxide particles is preferably 1.2 to 7.0, more preferably 1.2 to 4.0.
[0111]
The atomic ratio of Fe / Si on the outermost surface of the magnetic iron oxide particles is measured by X-ray photoelectron spectroscopy (XPS).
[0112]
When the content of silicon element is less than 0.4 mass% or the Fe / Si atomic ratio exceeds 7.0, the improvement effect on the magnetic toner, in particular, the improvement of the fluidity of the magnetic toner is low. When the content of silicon element is more than 2.0% by mass or the Fe / Si atomic ratio is less than 1.2, the environmental characteristics, particularly the long-term standing under high humidity, the chargeability is lowered. Furthermore, the durability of the magnetic toner and the dispersibility of the magnetic iron oxide particles in the binder resin are also reduced, which causes the release of the magnetic iron oxide particles from the toner during pulverization.
[0113]
The amount of silicon atoms on the outermost surface of the magnetic iron oxide particles correlates with the fluidity and water absorption of the magnetic iron oxide particles, and affects the toner physical properties of the magnetic toner containing the magnetic iron oxide particles.
[0114]
More preferably, the smoothness of the magnetic iron oxide particles is 0.3 to 0.8, preferably 0.45 to 0.7, and more preferably 0.5 to 0.7. The smoothness is related to the amount of pores on the surface of the magnetic iron oxide particles. When the smoothness is less than 0.3, there are many pores on the surface of the magnetic iron oxide and the water adsorption is promoted. As described above, since there are more adsorption sites where the adsorbed water is difficult to desorb, in the magnetic toner containing the magnetic iron oxide particles, the charging characteristics are deteriorated particularly when left for a long time under high humidity. Characteristic recovery is slow.
[0115]
More preferably, the bulk density of the magnetic iron oxide particles is 0.8 g / cm.^ThreeOr more, preferably 1.0 g / cm^ThreeSatisfy the above.
[0116]
Bulk density of magnetic iron oxide particles is 0.8 g / cm^ThreeIf it is less, the physical mixing with other toner materials during the production of the toner is lowered, the dispersibility of the magnetic iron oxide particles is lowered, and the magnetic iron oxide particles are easily released from the toner particles during the production.
[0117]
More preferably, the magnetic iron oxide particles have a BET specific surface area of 15.0 m.²/ G or less, preferably 12.0 m²/ G or less. BET specific surface area of magnetic iron oxide particles is 15.0m²When it exceeds / g, the water-adsorbing property of the magnetic iron oxide particles increases, the hygroscopic property of the magnetic toner containing the magnetic iron oxide particles becomes high, and the charging property decreases.
[0118]
Further, the magnetic iron oxide particles used in the present invention are 0.01 to 2.0% by mass (more preferably 0.05 to 1.0% by mass) of aluminum hydroxide in terms of aluminum element. It is preferable that it has been treated with an aluminum compound.
[0119]
Although the reason is not clear, it has been confirmed that it is possible to further stabilize the charging of the magnetic toner by treating the surface of the magnetic iron oxide particles with an aluminum compound.
[0120]
Furthermore, the Fe / Al atomic ratio on the outermost surface of the magnetic iron oxide particles used in the present invention is 0.3 to 10.0 (more preferably 0.3 to 5.0, still more preferably 0.3 to 2). .0). When the Fe / Al atomic ratio on the outermost surface of the magnetic iron oxide particles is 0.3 to 10.0, the charging characteristics of the toner can be maintained well even under high humidity.
[0121]
Further, the magnetic iron oxide particles used in the present invention preferably have an average particle size of 0.1 to 0.4 μm, preferably 0.1 to 0.3 μm.
[0122]
The method for measuring various physical property data in the present invention is described in detail below.
[0123]
(1) Particle size distribution of magnetic toner
The particle size distribution of the magnetic toner can be measured by various methods. In the present invention, the particle size distribution is performed using a Coulter counter. As a measuring device, Coulter Multisizer IIE (manufactured by Coulter Inc.) is used. As the electrolyte, first grade sodium chloride is used to prepare an approximately 1% NaCl aqueous solution. For example, ISOTON (R) -II (manufactured by Coulter Scientific Japan) 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 measurement apparatus is used to measure the volume and number of toner particles using a 100 μm aperture as the aperture. The number distribution is calculated. At this time, the measured data is obtained in a channel obtained by dividing a particle size of 1.59 to 64.0 μm into 256 parts. The data obtained in 256 channels is processed in 16 divisions, and the weight-based weight average particle diameter (D4) obtained from the volume distribution according to the present invention (the median value of each channel is the representative value for each channel) The number average particle diameter (D1) based on the number distribution determined from the number distribution, the amount of coarse powder based on the weight distribution (10.1 μm or more) determined from the volume distribution, and the number of fine particles based on the number distribution (4.00 μm) )
[0124]
(2) Half width y with respect to peak particle size x in the number particle size distribution of magnetic toner
The frequency% A at the peak particle size x is calculated from the 256ch particle size distribution (see FIG. 23) obtained by Coulter Multisizer IIE (manufactured by Coulter, Inc.) measured by the particle size distribution of the magnetic toner.
[0125]
The particle size at which the frequency% A at the peak particle size x takes a half value A / 2 is calculated from the particle size distribution and is defined as x1 and x2.
[0126]
At this time, it can be obtained by the half width y = x2−x1.
[0127]
In the number-based particle size distribution measured at 256ch by a Coulter counter, the relationship between the half-value width Y and the peak particle size X is
2.06x-9.113 ≦ y ≦ 2.06x-7.341 (7)
It is better to satisfy.
[0128]
In the number-based particle size distribution measured at 256 ch by a Coulter counter, when the relationship of the half-value width Y to the peak particle size X is Y> 2.06X-7.341, this toner is different from the cumulative number of the peak particle size X in comparison with the other number. This means that the toner is a broad toner having a so-called particle size distribution with a large cumulative number of particle sizes. In the case of such a toner, the toner charge distribution varies and developability, particularly durability, deteriorates. Further, in the number-based particle size distribution measured by a Coulter counter at 256 ch, when the relationship of the half-value width Y to the peak particle size X is Y <2.06X-9.113, this toner has a very sharp particle size distribution. Means that. In order to obtain a toner with a sharp particle size distribution, it is possible to produce it if the fine powder and coarse powder are largely cut in the classification process, but the yield of the toner with the desired particle size distribution is reduced. It's not realistic.
[0129]
(3) Fe / Si atomic ratio, Fe / Al atomic ratio
The Fe / Si atomic ratio and the Fe / Al atomic ratio on the outermost surface of the magnetic iron oxide particles are determined by XPS measurement. The condition is
XPS measuring device: ESCALAB, model 200-X manufactured by VG
X-ray photoelectron spectrometer
X-ray source: Mg Kα (300 W)
Analysis area: 2 x 3 mm
And
[0130]
(4) Bulk density
The bulk density of the magnetic iron oxide particles is measured according to the pigment test method of JIS-K-5101.
[0131]
(5) Smoothness
The smoothness D of the magnetic iron oxide particles is obtained as follows.
[0132]
[Equation 3]

[0133]
(6) BET specific surface area
The BET specific surface area of the magnetic iron oxide particles is measured as follows.
[0134]
The BET specific surface area is obtained by the BET multipoint method using a fully automatic gas adsorption amount measuring apparatus: Auto Soap 1 manufactured by Yuasa Ionics Co., Ltd., using nitrogen as the adsorption gas. As a sample pretreatment, deaeration is performed at 50 ° C. for 10 hours.
[0135]
(7) Average particle diameter and surface area of magnetic iron oxide particles
The measurement of the average particle diameter and the calculation of the surface area of the magnetic iron oxide particles are performed as follows.
[0136]
After taking a transmission electron micrograph of magnetic iron oxide particles and enlarging them by a factor of 40,000, arbitrarily select 250 particles, then select the Martin diameter in the projected diameter (the line segment that divides the projected area into two equal parts in a fixed direction). Is measured by a number average diameter.
[0137]
For the calculation of the surface area, the magnetic iron oxide is assumed to be spherical with an average particle diameter as the diameter, and the density of the magnetic iron oxide is measured by a usual method to determine the surface area value.
[0138]
[Expression 4]

[0139]
(8) Amount of different elements
The amount of heterogeneous elements in the magnetic iron oxide particles of the present invention is measured by fluorescent X-ray analysis using a fluorescent X-ray analyzer SYSTEM3080 (manufactured by Rigaku Denki Kogyo Co., Ltd.) according to JIS K0119 "General rules for fluorescent X-ray analysis". Measure by doing.
[0140]
For example, when the magnetic iron oxide particles having different elements are silicon elements, they are produced by the following method.
[0141]
Ferrous salt aqueous solution and Fe in the aqueous ferrous solution²⁺Magnetite particles were produced by aerating an oxygen-containing gas to a ferrous salt reaction aqueous solution containing ferrous hydroxide colloid obtained by reacting 0.90 to 0.99 equivalent of an alkali hydroxide aqueous solution with respect to In the production, the water-soluble silicate is previously added to either the alkali hydroxide aqueous solution or the ferrous salt containing the ferrous hydroxide colloid in terms of silicon element with respect to the total content (0 The ferrous hydroxide colloid is obtained by adding 50 to 99% of the mixture in the range of 4 to 2.0% by mass and conducting an oxidation reaction by aeration of an oxygen-containing gas while heating in a temperature range of 85 to 100 ° C. From this, magnetic iron oxide particles containing silicon element are produced. Thereafter, Fe remaining in the suspension after completion of the oxidation reaction²⁺1.00 equivalent or more of an aqueous alkali hydroxide solution and the remaining water-soluble silicate [1 to 50% of the total content (0.4 to 2.0% by mass)] and further 85 to 100 While heating in a temperature range of ° C., an oxidation reaction is performed to produce magnetic iron oxide particles containing silicon element. In the case of other elements, it can be obtained by using a water salt of the corresponding element in the same manner.
[0142]
Next, in the case of treating with aluminum hydroxide, 0.01 to 2.0 mass in terms of aluminum element with respect to the generated particles of water-soluble aluminum salt in the alkaline suspension in which magnetic iron oxide particles are generated. After adding so that it may become%, pH is adjusted to the range of 6-8, and it precipitates as an aluminum hydroxide on the magnetic iron oxide particle surface. Next, the magnetic iron oxide particles according to the present invention are obtained by filtration, washing with water, drying and crushing. Furthermore, as a method for adjusting the smoothness and the specific surface area to a preferable range, it is preferable to compress, shear and spatula using a mix muller or a raking machine.
[0143]
Examples of the silicate compound added to the magnetic iron oxide particles used in the present invention include silicates such as commercially available sodium silicate and silicates such as sol-like silicate produced by hydrolysis.
[0144]
Examples of the water-soluble aluminum salt to be added include aluminum sulfate.
[0145]
As the ferrous salt, iron sulfate generally produced as a by-product in the production of sulfuric acid titanium and iron sulfate produced as a by-product with the surface cleaning of the steel sheet can be used. Further, iron chloride can be used.
[0146]
Other suitable colorants that can be used in the magnetic toner include any suitable pigment or dye.
[0147]
Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount sufficient to maintain the optical density of the fixed image. It is preferable to use 0.1 to 20 parts by mass, preferably 1 to 10 parts by mass of pigment with respect to 100 parts by mass of the resin. For the same purpose, further dyes are used. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and it is preferable to use 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight of the dye with respect to 100 parts by weight of the resin. .
[0148]
Examples of the wax used in the toner of the present invention are as follows. For example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidation of aliphatic hydrocarbon wax such as oxidized polyethylene wax Or block copolymers thereof; plant waxes such as candelilla wax, carnauba wax, wax wax, jojoba wax; animal waxes such as beeswax, lanolin, whale wax; minerals such as ozokerite, ceresin, petrolactam Waxes based on fatty acid esters such as montanic acid ester wax and caster wax; those obtained by partially or fully deoxidizing fatty acid esters such as deoxidized carnauba wax That. Further, a saturated straight chain such as palmitic acid, stearic acid, montanic acid, or a long-chain alkyl carboxylic acid having a long-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; stearyl alcohol; Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amide, oleic acid amide An aliphatic amide such as lauric acid amide; a saturated fatty acid bisamide such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide; Unsaturated fatty acid amides such as oleic acid amide, hexamethylenebisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, Aromatic bisamides such as N'-distearylisophthalamide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap); aliphatic hydrocarbon waxes Wax grafted with vinyl monomers such as styrene and acrylic acid; partially esterified product of fatty acid and polyhydric alcohol such as behenic acid monoglyceride; methyl having hydroxyl group obtained by hydrogenating vegetable oil Ester compound And the like.
[0149]
Preferred waxes include polyolefins obtained by radical polymerization of olefins under high pressure; polyolefins obtained by purifying low molecular weight by-products obtained during polymerization of high molecular weight polyolefins; polymerized using catalysts such as Ziegler catalysts and metallocene catalysts under low pressures Polyolefins; Polyolefins polymerized using radiation, electromagnetic waves or light; Low molecular weight polyolefins obtained by thermally decomposing polymer polyolefins; Paraffin wax, microcrystalline wax, Fischer-Tropsch wax; Jindole method, Hydrocol method, Age method, etc. Synthetic hydrocarbon wax synthesized by the following: a synthetic wax having a compound having one carbon atom as a monomer, a hydrocarbon wax having a functional group such as a hydroxyl group or a carboxyl group; a hydrocarbon wax and a functional group A mixture of wax; styrene these waxes as a matrix, maleic acid ester, acrylate, methacrylate, waxes of such vinyl monomers with maleic anhydride graft modified.
[0150]
In addition, these waxes have a sharp molecular weight distribution using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a melt liquid crystal method, low molecular weight solid fatty acids, low molecular weight solids. An alcohol, a low molecular weight solid compound, and other impurities are preferably used.
[0151]
The wax used in the present invention preferably has a melting point of 65 to 160 ° C., more preferably 65 to 130 ° C., particularly 70 ° C. to 120 ° C. in order to balance the fixing property and the offset resistance. It is preferable that it is ° C. If it is less than 65 degreeC, blocking resistance will fall, and if it exceeds 160 degreeC, an offset-proof effect will become difficult to express.
[0152]
In the toner of the present invention, the total content of these waxes is 0.2 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin. It is. Moreover, you may use together with other waxes, as long as it does not have a bad influence.
[0153]
The melting point of the wax is defined as the melting point of the wax at the peak top temperature of the endothermic peak of the wax measured by DSC.
[0154]
In the present invention, for example, DSC-7 manufactured by Perkin Elmer can be used for DSC measurement of a wax or toner by a differential scanning calorimeter.
[0155]
The measurement method is performed according to ASTM D3418-82. The DSC curve used in the present invention is a DSC curve measured when the temperature is raised after raising the temperature once, taking the previous history, then lowering the temperature in the range of 10 ° C./min, and the temperature of 0 to 200 ° C. Is used.
[0156]
The toner of the present invention is preferably used with a charge control agent added.
[0157]
Examples of negative charge control agents include metal complexes of monoazo dyes described in JP-B-41-20153, JP-B-42-27596, JP-B-44-6397, and JP-B-45-26478; Nitrohumic acid and salts thereof described in JP-A-50-133838 or C.I. I. Dyes and pigments such as 14645; salicylic acid, naphthoic acid, dicarboxylic acid described in JP-B-55-42752, JP-B-58-41508, JP-B-58-7384, JP-B-59-7385 Zn, Al, Co, Cr, Fe, or Zr metal complex; sulfonated copper phthalocyanine pigment; styrene oligomer introduced with nitro group or halogen; chlorinated paraffin. In particular, an azo metal complex represented by the general formula (I) and a basic organic acid metal complex represented by the general formula (II) are excellent in dispersibility and effective in reducing the image density stability and fog. preferable.
[0158]
[Chemical formula 5]

[0159]
[Chemical 6]

[0160]
Among them, the azo metal complex represented by the above formula (I) is more preferable, and the azo iron complex represented by the following formula (III) or (IV) in which the central metal is Fe is most preferable.
[0161]
[Chemical 7]

[0162]
[Chemical 8]

[0163]
Next, specific examples of the azo iron complex represented by the above formula (III) are shown below.
[0164]
[Chemical 9]

[0165]
[Chemical Formula 10]

[0166]
Embedded image

[0167]
Specific examples of the charge control agent represented by the above formulas (I), (II), and (IV) are shown below.
[0168]
Embedded image

[0169]
Embedded image

[0170]
Embedded image

[0171]
These metal complex compounds can be used alone or in combination of two or more.
[0172]
The use amount of these charge control agents is preferably 0.1 to 5.0 parts by mass per 100 parts by mass of the binder resin from the viewpoint of the charge amount of the toner.
[0173]
On the other hand, there are the following substances that control the toner to be positively charged.
[0174]
Modified products of nigrosine by nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and oniums of their analogs, phosphonium salts Salts and their lake pigments; triphenylmethane dyes and their lake pigments (the rake agents include phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, Russian salts, etc.); metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicycle Diorgano tin borate compounds such as hexyl tin borate. These can be used alone or in combination of two or more.
[0175]
In the toner of the present invention, it is preferable that an inorganic fine powder or a hydrophobic inorganic fine powder is externally added to the toner particles. For example, it is preferable to add and use silica fine powder.
[0176]
As the silica fine powder used in the present invention, both a dry process produced by vapor phase oxidation of a silicon halogen compound or a dry silica called fumed silica and a wet silica produced from water glass can be used. Dry silica with fewer silanol groups on the surface and inside and no production residue is preferred.
[0177]
Further, the silica fine powder used in the present invention is preferably hydrophobized. The hydrophobizing treatment is applied by chemically treating with an organosilicon compound that reacts or physically adsorbs with silica fine powder. As a preferable method, a dry silica fine powder produced by vapor phase oxidation of a silicon halide compound is treated with a silane coupling agent or with a silane coupling agent and simultaneously with an organosilicon compound such as silicone oil. Is mentioned.
[0178]
As the silane coupling agent used for the hydrophobization treatment, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethyl Ethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetra Examples thereof include methyldisiloxane and 1,3-diphenyltetramethyldisiloxane.
[0179]
Examples of the organosilicon compound include silicone oil. A preferred silicone oil has a viscosity of approximately 3 × 10 at 25 ° C.^-Five~ 1x10^-3m²/ S is used. Dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, and fluorine modified silicone oil are preferred.
[0180]
Silicone oil treatment can be performed by directly mixing silica powder treated with a silane coupling agent and silicone oil using a mixer such as a Henschel mixer, or jetting silicone oil onto the base silica. Depending on how you do it. Alternatively, the silicone oil may be dissolved or dispersed in an appropriate solvent, and then mixed with the base silica fine powder to remove the solvent.
[0181]
In the toner of the present invention, an external additive other than silica fine powder may be used as necessary.
[0182]
For example, there are resin fine particles and inorganic fine particles that function as a charge auxiliary agent, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a release agent at the time of heat roll fixing, a lubricant or an abrasive.
[0183]
For example, a lubricant such as fluorine resin, zinc stearate, and polyvinylidene fluoride is preferable, and among these, polyvinylidene fluoride is preferable. Abrasives such as cerium oxide, silicon carbide, and strontium titanate, among which strontium titanate is preferable. Fluidity-imparting agents such as titanium oxide and aluminum oxide, particularly hydrophobic ones are preferred. Anti-caking agent. Conductivity imparting agents such as carbon black, zinc oxide, antimony oxide and tin oxide. A small amount of white fine particles and black fine particles having opposite polarity to the toner particles and the friction band properties can also be used as a developability improver.
[0184]
The inorganic fine powder or hydrophobic inorganic fine powder mixed with the toner is preferably used in an amount of 0.1 to 5 parts by mass (preferably 0.1 to 3 parts by mass) with respect to 100 parts by mass of the toner.
[0185]
Further, the magnetic toner of the present invention preferably has a Carr jetting index greater than 80, more preferably a Carr fluidity index greater than 60.
[0186]
Further, the magnetic toner of the present invention preferably has a Carr jetability index of 81 to 89. Furthermore, the magnetic toner of the present invention preferably has a Carr's fluidity index of 61 to 79.
[0187]
The fluidity index and jetability index of the magnetic toner are measured by the following method. Using a powder tester P-100 (manufactured by Hosokawa Micron Corporation), parameters of repose angle, collapse angle, difference angle, degree of compression, degree of aggregation, spatula angle and degree of dispersion are measured. The values obtained for each are applied to Carr's flowability index table and jet flow index table, converted into each index of 25 or less, and the sum of the indexes calculated from each parameter is used as the liquidity index / jet property index. Calculated. The measurement method of each parameter is shown below.
[0188]
▲ 1 angle of repose
The toner is deposited on a circular table having a diameter of 8 cm through a mesh having a mesh size of 710 μm. At this time, the toner is deposited so that the toner overflows from the end of the table. The angle of repose was determined by measuring the angle formed between the ridge line of the toner deposited on the table and the circular table surface with a laser beam.
[0189]
(2) Compression degree
The degree of compression can be determined from the loosely packed bulk density (loose apparent specific gravity A) and the tapping bulk density (hardened apparent specific gravity P).
Compressibility (%) = 100 (PA) / P
○ Lack apparent specific gravity measurement method 150 g of toner is gently poured into a cup having a diameter of 5 cm, a height of 5.2 cm, and a capacity of 100 cc. When the measurement cup is filled with toner, the surface of the toner is ground, and the loose apparent specific gravity is calculated from the amount of toner filled in the cup.
○ Measurement method of solid apparent specific gravity Add the attached cap to the measuring cup used for loose apparent specific gravity. Fill the cup with toner and tap the cup 180 times. When tapping is complete, remove the cap and remove excess toner from the cup. The solid apparent specific gravity is calculated from the amount of toner filled in the cup.
The apparent specific gravity value is inserted into the compression degree formula to obtain the compression degree.
[0190]
▲ 3 ▼ Spatula corner
Place the bottom of the 10 cm x 15 cm bat against the 3 cm x 8 cm spatula. Deposit toner on the spatula. At this time, the toner is deposited so as to rise on the spatula. Thereafter, only the bat is gently lowered, and the inclination angle of the toner side surface remaining on the spatula is measured with a laser beam.
[0191]
Then, after applying an impact once with a shocker attached to the spatula, the spatula angle is measured again. The average of this measured value and the measured value before giving an impact was calculated as a spatula angle.
[0192]
(4) Degree of aggregation
On the shaking table, sieves are set in the order of 250 μm, 150 μm, and 75 μm from the top. The vibration swing width is 1 mm, the vibration time is 20 seconds, and 5 g of toner is gently put on it to vibrate. After the vibration stops, measure the weight remaining on each sieve.
(Amount of toner remaining on upper screen) ÷ 5 (g) × 100... A
(Amount of toner remaining on the middle screen) ÷ 5 (g) × 100 × 0.6... B
(The amount of toner remaining on the lower screen) ÷ 5 (g) × 100 × 0.2... C
a + b + c = calculation degree (%)
[0193]
The value obtained from the parameters is converted to an index of 25 or less according to the Carr's flowability index and jetability index table (Chemical Engineering. Jan. 18.1965), and the total of these values (1) + (2) + (3) + (4) = Carr's fluidity index.
[0194]
(5) Collapse angle
After measuring the angle of repose, shock is applied three times with a shocker to the bat on which the circular table for measurement is placed. Thereafter, the angle of the toner remaining on the table is assumed using a laser beam, and the collapse angle is obtained.
[0195]
▲ 6 ▼ Difference angle
The difference between the angle of repose and the collapse angle is the difference angle.
[0196]
(7) degree of dispersion
10 g of toner is dropped as a lump onto a watch glass having a diameter of 10 cm from a height of about 60 cm. Then, the toner remaining on the watch glass is measured, and the degree of dispersion is obtained by the following equation.
Dispersity (%) = ((10− (amount of toner remaining on the plate)) × 10
[0197]
The sum of the index that can be converted from the values of (5), (6), and (7) and the index corresponding to the fluidity index value obtained above can be obtained as the jetability index from the aforementioned Carr table.
[0198]
As a result of the above measurement, the jet flow index is greater than 80 (more preferably 81 to 89), more preferably the Carr's flow index is greater than 60 (more preferably 61 to 79). In the case of the magnetic toner shown in the figure, even if the cartridge is filled with the magnetic toner at a high filling rate, high fluidity is reproduced at the time of stirring by the stirring member, and therefore, from the toner container in the cartridge toward the developing sleeve. Thus, the magnetic toner is easily conveyed uniformly, and stable development characteristics can be obtained even when the printer is filled in a high-speed printer or a large-capacity cartridge. In the magnetic toner of the present invention, it is possible to achieve an appropriate jetability index and fluidity index by changing the particle size and shape of the magnetic toner particles, the amount of external additive, and the adhesion state. As described above, in the magnetic toner, by controlling the particles having free iron element to 100 to 350 per 10,000 toner particles, the fluidity is lowered due to aggregation of the free magnetic iron oxide particles. In addition, by changing the stirring state by changing the shape of the stirring blade used during external addition, the filling amount to the mixing device, and the stirring mode, the above jetting index and fluidity index can be achieved. Can do.
[0199]
When the magnetic toner has a jetability index of 80 or less, high fluidity can be obtained, but once clogged, it is difficult to flow even if force is applied. Not. As a result, the magnetic toner is difficult to be conveyed to the developing sleeve and is charged with the magnetic toner on the developing sleeve in a non-uniform manner, so that the magnetic toner is easily charged unevenly and the image is likely to be uneven.
[0200]
Also, when the jet property index of the magnetic toner is 80 or less and the fluidity index of the toner is 60 or less, the magnetic toners tend to aggregate and are difficult to flow, so the magnetic toner is fused to the sliding portion in the cartridge. Is likely to occur.
[0201]
Further, in the magnetic toner of the present invention, when the absolute value of the triboelectric charge amount with respect to the iron powder carrier is | Qd |
70 ≧ | Qd | ≧ 20 μC / g
It is preferable that Since the value of the triboelectric charge varies greatly depending on the surface shape of the magnetic toner and the state of exposure of the magnetic iron oxide particles to the surface of the magnetic toner particles, in order to obtain a desired triboelectric charge amount in the present invention, as described above, it is circular. In addition, it controls the release rate of magnetic iron oxide particles from the toner particles and changes the type and amount of the external additive. Furthermore, the shape of the stirring blade used at the time of external addition, the filling amount to the mixing device, and the stirring mode are changed. It is important to change the stirring state.
[0202]
A method for measuring Qd is shown below.
[0203]
For the measurement, a charge amount measuring apparatus shown in FIG. 19 is used. Iron powder having a distribution of 50 to 70% by mass in a particle size range of 106 to 150 μm and a distribution of 20 to 50% by mass in a range of particle size 75 to 106 μm as an iron powder carrier in an environment of a temperature of 23 ° C. and a relative humidity of 60% Using a carrier (for example, DSP138 (manufactured by Dowa Iron Powder Co., Ltd.)), a mixture obtained by adding 1.0 g of magnetic toner to 9.0 g of iron powder carrier is put in a polyethylene bottle having a capacity of 50 to 100 ml and shaken by hand 50 times.
[0204]
Next, 1.0 to 1.2 g of the mixture is placed in a metal measuring vessel 902 having a 500 mesh screen 903 at the bottom, and a metal lid 904 is placed. The total weight of the measurement container 902 at this time is weighed and is defined as W1 (g). Next, in the suction device 901 (at least the part in contact with the measurement container 902 is suctioned), the pressure of the vacuum gauge 905 is set to 2 kPa by suction from the suction port 907 and adjusting the air volume control valve 906.
[0205]
In this state, suction is performed for 1 minute to remove the developer by suction. The potential of the electrometer 909 at this time is set to V (volt). Here, 8 is a capacitor, and the capacity is C (μF). Moreover, the weight of the whole measuring machine after suction is weighed and is defined as W2 (g). The frictional charge amount Qd (μC / g) of the magnetic toner is calculated as follows:
Qd = CV / (W1-W2)
[0206]
When the absolute value of the triboelectric charge amount of the magnetic toner with respect to the iron powder carrier is 70 μC / g ≦ | Qd |, the developability is reduced due to charge-up particularly under low humidity. When | Qd | ≦ 20 μC / g, due to the low charge amount, the appropriate electrostatic cohesive force of the magnetic toner on the developer carrier and the appropriate magnetic restraint force on the developer carrier cannot be obtained. , The magnetic toner cannot be faithfully transferred to the electrostatic latent image, and the developability is lowered.
[0207]
The magnetic toner of the present invention preferably has a maximum endothermic peak of DSC curve measured by a differential scanning calorimeter of the toner at 60 to 120 ° C. When the maximum endothermic peak is less than 60 ° C., the offset resistance and blocking resistance are lowered. When the maximum endothermic peak exceeds 120 ° C., the fixability is lowered.
[0208]
  Furthermore, the toner of the present invention has a DSC curve measured by a differential scanning calorimeter.maximumThe endothermic peak is 60-120 ° C,Sub endothermicMore preferably, the peak is at 60 to 160 ° C., and the endothermic peaks are separated by 20 ° C. or more.
[0209]
When the difference between the endothermic peaks is less than 20 ° C., the function separation effect of the fixing property and the releasability is hardly exhibited. In this way, the presence of the endothermic peak as described above can moderately adjust the effect of plasticizing the magnetic toner and the effect of releasing the toner, so that both the fixing property, the offset resistance, and the blocking resistance can be balanced. Become. Furthermore, the plasticity effect can be more effectively exhibited by having the circularity of the present invention, and the releasing action can be exhibited in a wide temperature range.
[0210]
Hereinafter, preferred embodiments of a toner production method of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an example of a flowchart showing an outline of a toner manufacturing method of the present invention. As shown in the flowchart, the production method of the present invention does not require a classification step before the pulverization treatment, and the pulverization step and the classification step are preferably performed in one pass.
[0211]
In the toner manufacturing method, it is possible to control the number of free magnetic iron oxides and the circularity of the toner by using a specific toner constituent material and selecting various manufacturing conditions to manufacture the toner. Generally, a coarsely pulverized product obtained by melt-kneading a mixture containing at least a binder resin, a colorant and a wax, cooling the obtained kneaded product, and then pulverizing the cooled product by a pulverizing means is used as a powder raw material. Used as. And a rotor composed of a rotating body having at least a predetermined amount of pulverized raw material attached to a central rotating shaft, and a stator disposed around the rotor with a predetermined distance from the rotor surface. In addition, the annular space formed by maintaining the interval is introduced into a mechanical pulverizer configured to be in an airtight state, and the rotor of the mechanical pulverizer is rotated at high speed to be pulverized. Grind the object. Next, the finely pulverized pulverized raw material is introduced into a classification step and classified to obtain toner particles composed of a group of particles having a preferable particle size. At this time, in the classification step, a multi-split airflow classifier having at least a coarse powder region, a medium powder region, and a fine powder region is preferably used. For example, when a three-part airflow classifier is used, the powder raw material is classified into at least three types of fine powder, medium powder, and coarse powder. In the classification process using such a classifier, the coarse powder composed of particles larger than the preferred particle size and the ultra fine powder composed of particles smaller than the preferred particle size are removed, and the medium powder is used as toner particles. The toner is used as it is, or after being mixed with an external additive such as hydrophobic colloidal silica and used as a toner.
[0212]
The ultrafine powder composed of particles having a particle size less than the preferred particle size classified in the classification step is generally supplied to a melt-kneading step for producing a powder raw material composed of a toner material introduced into the pulverization step. Can be reused or discarded.
[0213]
FIG. 2 shows an example of a toner manufacturing apparatus system. The powder raw material, which is a toner raw material introduced into the apparatus system, is a colored resin particle powder containing at least a binder resin, a colorant, and a wax. The powder raw material includes, for example, a binder resin, A mixture of magnetic iron oxide and wax is melt-kneaded, the resulting kneaded product is cooled, and the cooled product is coarsely pulverized by a pulverizing means.
[0214]
In this apparatus system, a pulverized raw material to be a toner powder raw material is introduced into a mechanical pulverizer 301 as a pulverizing means through a first fixed amount feeder 315 in a predetermined amount. The introduced pulverized raw material is instantaneously pulverized by the mechanical pulverizer 301 and is introduced into the second fixed amount feeder 2 through the collecting cyclone 229. Subsequently, it is supplied into the multi-division airflow classifier 1 which is a classification means through the vibration feeder 3 and further through the raw material supply nozzle 16.
[0215]
Further, in this apparatus system, a predetermined amount introduced from the first fixed amount feeder 315 to the mechanical pulverizer 301 as the pulverizing means, and the multi-division airflow classifier 1 as the classification means from the second constant amount feeder 2 When the predetermined amount introduced from the first fixed amount feeder 315 to the mechanical crusher 301 is 1, the relationship from the introduced predetermined amount is introduced from the second constant amount feeder 2 to the multi-split airflow classifier 1 The predetermined amount is preferably 0.7 to 1.7, more preferably 0.7 to 1.5, and still more preferably 1.0 to 1.2 in terms of toner productivity and production efficiency. preferable.
[0216]
In general, the airflow classifier of the present invention is used by connecting devices to each other by a communication means such as a pipe, and being incorporated in an apparatus system. A preferred example of such a device system is shown in FIG. The integrated apparatus system shown in FIG. 2 communicates the multi-division classifying apparatus 1 (classifying apparatus shown in FIG. 6), the quantitative feeder 2, the vibration feeder 3, the collecting cyclone 4, the collecting cyclone 5, and the collecting cyclone 6. It is connected by.
[0217]
In this apparatus system, the powder is fed to the fixed quantity feeder 2 by an appropriate means, and then introduced into the three-division classifier 1 through the vibration feeder 3 by the raw material supply nozzle 16. At the time of introduction, the powder is introduced into the three-class classifier 1 at a flow rate of 10 to 350 m / sec. Since the size of the classification chamber of the three-division classifier 1 is usually [10 to 50 cm] × [10 to 50 cm], the powder is instantaneously divided into three or more types of particles in 0.1 to 0.01 seconds or less. Can be classified. Then, the three-class classifier 1 classifies the particles into large particles (coarse particles), intermediate particles, and small particles. Thereafter, the large particles are sent to the collecting cyclone 6 through the discharge conduit 11 a and returned to the mechanical crusher 301. The intermediate particles are discharged out of the system through the discharge conduit 12a, collected by the collecting cyclone 5, and collected as toner. The small particles are discharged out of the system through the discharge conduit 13a and collected by the collecting cyclone 4 and supplied to the melt-kneading process for producing the powder raw material made of the toner material for reuse or disposal. Is done. The collecting cyclones 4, 5, 6 can also serve as a suction pressure reducing means for sucking and introducing the powder into the classification chamber via the raw material supply nozzle 16. In addition, it is preferable that the large particles classified at this time are reintroduced into the first constant supply machine 315, mixed into the powder raw material, and pulverized again by the mechanical pulverizer 301.
[0218]
Further, the reintroduction amount of large particles (coarse particles) reintroduced from the multi-split airflow classifier 1 into the mechanical pulverizer 301 is based on the mass of the finely pulverized product supplied from the second fixed amount supply device 2. From 0 to 10.0% by mass, more preferably from 0 to 5.0% by mass, is preferable for toner production. When the reintroduction amount of large particles (coarse particles) reintroduced from the multi-split air classifier 1 into the mechanical pulverizer 301 exceeds 10.0% by mass, the dust concentration in the mechanical pulverizer 301 increases. The load on the apparatus itself is increased, and at the same time, it is excessively pulverized at the time of pulverization, and the toner surface is easily altered by heat, and the magnetic iron oxide is easily released from the toner particles and fused in the machine.
[0219]
In this apparatus system, the particle size of the powder raw material is preferably 95 mass% or more for 18 mesh pass (ASTME-11-61) and 90 mass% or more for 100 meshon (ASTME-11-61). .
[0220]
Further, in this apparatus system, in order to obtain a toner having a sharp particle size distribution with a weight average particle size of 10 μm or less (more preferably 8 μm or less), the weight average particle of the finely pulverized product finely pulverized by a mechanical pulverizer is used. The diameter is 5 to 10 μm, 4.0 μm or less is preferably 70% by number or less, more preferably 65% by number or less, and 10.1 μm or more is 25% by volume or less, and further preferably 20% by volume or less. The classified medium powder has a weight average particle size of 5 to 10 μm, 4.0 μm or less of 40 number%, further 35 number% or less, 10.1 μm or more of 25 volume% or less, It is preferable that it is 20 volume% or less.
[0221]
In the apparatus system to which the toner manufacturing method of the present invention is applied, the first classification step before the pulverization process is not required, and the pulverization step and the classification step can be performed in one pass.
[0222]
A mechanical pulverizer that is preferably used as the pulverizing means used in the toner production method of the present invention will be described. Examples of the mechanical pulverizer include a pulverizer KTM manufactured by Kawasaki Heavy Industries, Ltd. and a turbo mill manufactured by Turbo Industry Co., Ltd. It is preferable to use these apparatuses as they are or as they are appropriately improved.
[0223]
Among these, using a mechanical pulverizer as shown in FIG. 3, FIG. 4 and FIG. 5 and producing a toner using a specific raw material as a toner constituent material, the shape of toner particles and free magnetic iron oxide This is preferable as a method that can be produced by controlling the number of particles. Furthermore, since the powder raw material can be easily pulverized, efficiency is improved, which is preferable.
[0224]
In the conventional collision type airflow pulverization, toner particles are collided with the collision surface of the collision member and pulverized by the impact, so that free magnetic iron oxide particles are easily generated during the collision. Further, since the pulverized toner becomes irregular and angular, the magnetic iron oxide particles are easily dropped from the toner particles. It is also possible to modify the shape and surface properties of toner particles produced by collision-type airflow pulverization by mechanical impact (hybridizer). However, in collision-type pulverization, toner particles are formed on the collision surface of the collision member. Is caused to collide and pulverized by the impact, so that free magnetic iron oxide particles are likely to be generated at the time of collision. After that, by modifying the shape of the particles by mechanical impact and making the shape close to a sphere, the magnetic iron oxide particles are less likely to fall off from the toner compared to the amorphous toner, but the toner using a mechanical pulverizer It is difficult to control the shape of the toner and the number of free magnetic iron oxide particles as compared with the above manufacturing method.
[0225]
The mechanical pulverizer shown in FIGS. 3, 4 and 5 will be described below. 3 shows a schematic cross-sectional view of an example of a mechanical pulverizer, FIG. 4 shows a schematic cross-sectional view along the line DD ′ in FIG. 3, and FIG. 5 shows the rotor shown in FIG. A perspective view of 314 is shown. As shown in FIG. 3, the apparatus has a large number of grooves on a surface that rotates at a high speed, which is a casing 313, a jacket 316, a distributor 220, and a rotating body that is attached to the central rotating shaft 312 in the casing 313. The provided rotor 314, the stator 310 provided with a large number of grooves on the outer periphery of the rotor 314, which are arranged at regular intervals, and the raw material input for introducing the raw material to be treated The port 311 includes a raw material discharge port 302 for discharging the processed powder.
[0226]
For example, the pulverization operation in the mechanical pulverizer is performed as follows. That is, when a predetermined amount of powder raw material is introduced from the powder inlet 311 of the mechanical pulverizer shown in FIG. 3, the particles are introduced into the pulverization chamber and are rotated on the surface rotating at high speed in the pulverization chamber. The impact generated between the rotor 314 provided with a large number of grooves and the stator 310 provided with a large number of grooves on the surface, a large number of ultrahigh-speed vortices generated behind the rotor 314, and the resultant It is crushed instantly by high-frequency pressure vibration. Thereafter, the material passes through the material discharge port 302 and is discharged. The air carrying the toner particles passes through the pulverization chamber and is discharged out of the apparatus system through the material discharge port 302, the pipe 219, the collecting cyclone 229, the bag filter 222, and the suction filter 224. Is done. In the present invention, since the powder raw material is pulverized, a desired pulverization treatment can be easily performed without increasing fine powder and coarse powder.
[0227]
Further, when the pulverized raw material is pulverized with a mechanical pulverizer, the cold air generating means 321 blows cold air into the mechanical pulverizer together with the powder raw material, and the mechanical pulverizer body has a structure having a jacket structure 316, By passing cooling water (preferably an antifreeze such as ethylene glycol), the atmospheric temperature in the pulverizer is 0 ° C. or lower, more preferably −5 to −15 ° C., and further preferably −7 to −12 ° C. Is preferable from the viewpoint of toner productivity. By changing the room temperature of the spiral chamber in the pulverizer to 0 ° C. or less, more preferably −5 to −15 ° C., and still more preferably −7 to −12 ° C., the surface of the toner particles is altered by heat, particularly on the surface of the toner particles. The release of magnetic iron oxide particles can be suppressed, and the pulverized raw material can be efficiently pulverized. When the atmospheric temperature in the pulverizer exceeds 0 ° C., it is preferable from the viewpoint of toner productivity because the surface of the toner particles is deteriorated by heat at the time of pulverization, and in particular, the magnetic iron oxide particles existing on the surface of the toner particles are liable to be released. Absent. Further, if the atmospheric temperature in the pulverizer is to be operated at a temperature lower than −15 ° C., the refrigerant (alternative chlorofluorocarbon) used in the cold air generating means 321 must be changed to chlorofluorocarbon.
[0228]
Currently, chlorofluorocarbons are being eliminated from the viewpoint of protecting the ozone layer. Use of chlorofluorocarbon as the refrigerant of the cold air generating means 321 is not preferable from the viewpoint of global environmental problems.
[0229]
Cooling water (preferably an antifreeze such as ethylene glycol) is supplied into the jacket from the cooling water supply port 317 and discharged from the cooling water discharge port 318.
[0230]
Further, when the pulverized raw material is pulverized by a mechanical pulverizer, the temperature difference ΔT (T2−T1) between the room temperature T1 of the spiral chamber 212 and the room temperature T2 of the rear chamber 321 is set to 30 to 80 ° C. More preferably, by setting the temperature to 35 to 75 ° C., and more preferably 37 to 72 ° C., the surface alteration of the toner particles due to heat, in particular, the release of the magnetic iron oxide particles present on the toner particle surface can be suppressed, The pulverized raw material can be pulverized efficiently. When ΔT between the temperature T1 (inlet temperature) and the temperature T2 (outlet temperature) of the mechanical pulverizer is smaller than 30 ° C., there is a possibility that a short pass is caused without being pulverized, which is preferable from the viewpoint of toner performance. Absent. On the other hand, when the temperature is higher than 80 ° C., it may be excessively pulverized at the time of pulverization. As a result, the magnetic iron oxide particles are liberated and the surface of the toner particles is altered by heat, especially the magnetic iron oxide particles present on the toner particle surface. In addition, it is not preferable from the viewpoint of toner productivity because it tends to cause in-machine fusion.
[0231]
Further, when the pulverized raw material is pulverized by a mechanical pulverizer, the inlet temperature of the mechanical pulverizer is 0 ° C. or lower with respect to the glass transition point (Tg) of the binder resin and is 60 to 75 ° C. higher than Tg. Lowering is preferable from the viewpoint of toner productivity. By controlling the inlet temperature of the mechanical pulverizer to 0 ° C. or lower and lower by 60 to 75 ° C. than Tg, the surface alteration of the toner particles due to heat, particularly the release of magnetic iron oxide present on the toner particle surface can be suppressed. And the pulverized raw material can be efficiently pulverized. The outlet temperature is preferably 5 to 30 ° C., more preferably 10 to 20 ° C. lower than Tg. By making the outlet temperature of the mechanical pulverizer 5 to 30 ° C. lower than Tg, the surface alteration of the toner particles due to heat, in particular, the release of the magnetic iron oxide particles present on the toner particle surface can be suppressed, and the pulverization can be performed efficiently. The raw material can be crushed.
[0232]
Further, the peripheral speed of the tip of the rotating rotor 314 is preferably 80 to 180 m / s, more preferably 90 to 170 m / s, and still more preferably 100 to 160 m / s. It is preferable from the point. The peripheral speed of the rotating rotor 314 is preferably 80 to 180 m / s, more preferably 90 to 170 m / s, and still more preferably 100 to 160 m / s. Furthermore, the release of magnetic iron oxide particles due to over-pulverization can be suppressed, and the pulverized raw material can be efficiently pulverized. When the peripheral speed of the rotor is lower than 80 m / s, a short pass is easily caused without being pulverized, which is not preferable from the viewpoint of toner performance. Further, when the peripheral speed of the rotor 314 is higher than 180 m / s, the load on the apparatus itself is increased, and at the same time, it is excessively pulverized during pulverization and the magnetic iron oxide particles are easily released. Furthermore, excessive pulverization is not preferable from the viewpoint of toner productivity because the surface of the toner particles may be altered by heat, particularly the magnetic iron oxide particles existing on the surface of the toner particles may be liberated or fused in the machine.
[0233]
The minimum distance between the rotor 314 and the stator 310 is preferably 0.5 to 10.0 mm, more preferably 1.0 to 5.0 mm, and still more preferably 1.0 to 3.0 mm. It is preferable that The distance between the rotor 314 and the stator 310 is preferably 0.5 to 10.0 mm, more preferably 1.0 to 5.0 mm, and still more preferably 1.0 to 3.0 mm. Thus, insufficient pulverization of the toner, excessive pulverization, and release of magnetic iron oxide particles due to excessive pulverization can be suppressed, and the pulverized raw material can be efficiently pulverized. When the distance between the rotor 314 and the stator 310 is larger than 10.0 mm, it is not preferable from the viewpoint of toner performance because a short pass is likely to occur without being pulverized. Further, when the distance between the rotor 314 and the stator 310 is smaller than 0.5 mm, the load on the apparatus itself is increased, and at the same time, it is excessively pulverized during pulverization and the magnetic iron oxide particles are easily released. Furthermore, excessive pulverization is liable to cause surface modification of toner particles and in-machine fusion due to heat, which is not preferable from the viewpoint of toner productivity.
[0234]
In addition, the pulverizer controls the generation of free magnetic iron oxide particles by controlling the surface roughness of the pulverized surfaces of the rotor and the stator to an appropriate state, and has good developability, transferability and chargeability. A magnetic toner can be obtained. That is, the center line average roughness Ra of the grinding surfaces of the rotor 314 and the stator 310 is 10.0 μm or less, more preferably 2.0 to 10.0 μm, and the maximum roughness Ry is 60.0 μm or less, more preferably. Is 25.0 to 60.0 μm, and the ten-point average roughness Rz is 40.0 μm or less, more preferably 20.0 to 40.0 μm. When the center line average roughness Ra of the pulverized surfaces of the rotor and the stator exceeds 10.0 μm, the maximum roughness Ry exceeds 60.0 μm, and the ten-point average roughness Rz exceeds 40.0 μm, pulverization occurs. Sometimes it is excessively pulverized and the magnetic iron oxide particles are easily released. Furthermore, excessive pulverization is not preferable from the viewpoint of toner productivity because the surface of the toner particles may be altered by heat, particularly the magnetic iron oxide particles existing on the surface of the toner particles may be liberated or fused in the machine.
[0235]
In addition, the value of each analysis parameter of the surface roughness is a laser focus displacement meter LT-8100 (manufactured by Keyence Co., Ltd.) capable of non-contact measurement and surface shape measurement software Tres-Valle Lite (Mitani Corporation) ), Measure several times at random measurement points, and determine the average value. At this time, the measurement is performed with the reference length set to 8 mm, the cut-off value set to 0.8 mm, and the moving speed set to 90 μm / sec.
[0236]
Among the analysis parameters for surface roughness, the centerline roughness Ra is extracted from the roughness curve in the direction of the centerline, with a reference length L, the centerline of the extracted portion being the X axis, and the direction of the vertical magnification Is a Z-axis, and the roughness curve is expressed by Z = f (x), it is determined by obtaining the following equation.
[0237]
[Equation 5]

[0238]
In addition, the maximum roughness Ry is extracted from the roughness curve by the reference length in the direction of the average line, and the distance between the peak portion and the valley bottom portion of the extracted portion is measured in the direction of the vertical magnification of the roughness curve. decide. The ten-point average roughness Rz was extracted from the roughness curve by the reference length in the direction of the average line, and measured from the average line of the extracted portion in the direction of the vertical magnification, from the highest peak to the fifth peak. It is determined by calculating the sum of the average value of the absolute values of the altitude and the average value of the absolute values of the bottom from the lowest valley bottom to the fifth.
[0239]
A known method is used as the roughening treatment of the grinding surface of the rotor and / or the stator.
[0240]
However, in a mechanical pulverizer in which the base material of the pulverized surface of the rotor and / or stator is only roughened, the pulverized surface of the rotor and / or stator is worn in a short time, and toner production It is not preferable in terms of efficiency, and wear resistance treatment of the pulverized surface of the rotor and / or stator is required.
[0241]
By roughening the base material of the pulverized surface of the rotor and / or stator as a pre-process, and anti-wearing the base material as a post-process, the generation of free magnetic iron oxide can be easily suppressed and good development can be achieved. Thus, it is possible to obtain a toner capable of maintaining the properties and to reduce the wear of the grinding surfaces of the rotor and the stator, and to stably pulverize the toner for a long time.
[0242]
A known method is used for the abrasion resistance treatment of the pulverized surface of the rotor and / or stator, and among these, the treatment by nitriding is the most preferable.
[0243]
The nitriding is a surface hardening treatment method for the purpose of improving the wear resistance and fatigue resistance of a work material. The nitriding is heated at an appropriate temperature for an appropriate time, and nitrogen is partially or entirely applied to the work material surface. This is a heat treatment for diffusing and forming a nitride layer.
[0244]
By roughening the base material of the pulverized surface of the rotor and / or stator as a pretreatment and nitriding the base material as a post process, the generation of free magnetic iron oxide particles can be easily suppressed, A toner capable of maintaining good developability is obtained, wear of the pulverized surfaces of the rotor and the stator is reduced, and the kneaded material can be stably pulverized over a long period of time, which is preferable in terms of toner production efficiency.
[0245]
The pulverization method of the kneaded product does not require the first classification step before the pulverization step, so that the toner particles are finely divided and electrostatic aggregation between the particles is increased, and the toner particles originally sent to the second classification means Is recirculated to the first classifying means, and fine powder and super fine powder which are excessively pulverized are not generated. Furthermore, in addition to a simple configuration, since a large amount of air is not required to pulverize the pulverized raw material, the power consumption is low and the energy cost can be kept low.
[0246]
Next, an airflow classifier that is preferably used as a classifying means constituting the toner manufacturing method will be described.
[0247]
As an example of a preferable multi-division airflow classifier used in the present invention, an apparatus of the type shown in FIG. 6 (cross-sectional view) is illustrated as a specific example.
[0248]
In FIG. 6, the side wall 22 and the G block 23 form a part of the classification chamber, and the classification edge blocks 24 and 25 include the classification edges 17 and 18. The installation position of the G block 23 can be slid left and right. Further, the classification edges 17 and 18 can be rotated around the shafts 17a and 18a, and the classification edge tip position can be changed by rotating the classification edge. The classification edge blocks 24 and 25 can be slid left and right, and accordingly the knife edge type classification edges 17 and 18 also slide to the left and right. By the classification edges 17 and 18, the classification area 30 of the classification chamber 32 is divided into three.
[0249]
A raw material supply port 40 for introducing the raw material powder is provided at the rearmost end portion of the raw material supply nozzle 16, and a high pressure air nozzle 41 and a raw material powder introduction nozzle 42 are provided at the rear end portion of the raw material supply nozzle 16. The raw material supply nozzle 16 having an opening in the classification chamber 32 is provided on the right side of the side wall 22, and the Coanda block 26 is installed so as to draw an elliptical arc in the extending direction of the lower tangent of the raw material supply nozzle 16. . The left block 27 of the classification chamber 32 includes a knife-edge type inlet edge 19 on the right side of the classification chamber 32, and inlet tubes 14 and 15 that open to the classification chamber 32 are provided on the left side of the classification chamber 32. It is. In addition, as shown in FIG. 6, the inlet pipes 14 and 15 are provided with first gas introduction adjusting means 20 and second gas introduction adjusting means 21 such as dampers, and static pressure gauges 28 and 29.
[0250]
The positions of the classification edges 17 and 18, the G block 23, and the inlet edge 19 are adjusted according to the type of toner that is the classification processing raw material and the desired particle size.
[0251]
In addition, the upper surface of the classification chamber 32 has discharge ports 11, 12, and 13 that open to the classification chamber in correspondence with the respective classification areas, and the discharge ports 11, 12, and 13 have communication means such as pipes. It is connected, and each may be provided with opening / closing means such as valve means.
[0252]
The raw material supply nozzle 16 includes a right-angle cylinder part and a pyramidal cylinder part, and the ratio of the inner diameter of the right-angle cylinder part to the inner diameter of the narrowest part of the pyramid cylinder part is 20: 1 to 1: 1, preferably 10: 1. When it is set to 2: 1, a good introduction speed can be obtained.
[0253]
For example, the classification operation in the multi-division classification area configured as described above is performed as follows. That is, the classification chamber is depressurized through at least one of the discharge ports 11, 12, and 13, and the air current flowing by the depressurization and the high-pressure air supply nozzle 41 are injected through the raw material supply nozzle 16 having an opening in the classification chamber. Due to the ejector effect of compressed air, the powder is preferably sprayed into the classification chamber through the raw material supply nozzle 16 and dispersed at a flow rate of 10 to 350 m / s.
[0254]
The particles in the powder introduced into the classification chamber move along a curved surface due to the action of the Coanda effect of the Coanda block 26 and the action of a gas such as air flowing at that time. Depending on the magnitude of the inertial force, large particles (coarse particles) are the first fraction outside the air flow, ie outside the classification edge 18, intermediate particles are the second fraction between the classification edges 18 and 17, small particles Is classified into a third fraction inside the classification edge 17, the classified large particles are discharged from the discharge port 11, the classified intermediate particles are discharged from the discharge port 12, and the classified small particles are discharged from the discharge port 13, respectively.
[0255]
In the above powder classification, the classification point is mainly determined by the edge tip positions of the classification edges 17 and 18 with respect to the lower end portion of the Coanda block 26 where the powder jumps into the classification chamber 32. Furthermore, the classification point is affected by the suction flow rate of the classification airflow or the ejection speed of the powder from the raw material supply nozzle 16.
[0256]
Further, in the toner production method and production system, by controlling the pulverization and classification conditions, a toner having a sharp particle size distribution with a weight average particle diameter of 5 to 12 μm (especially 5 to 10 μm) is efficiently produced. It can be generated well.
[0257]
Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauter mixer, turbulizer, cyclomix (made by Hosokawa Micron); Pacific Kiko Co., Ltd.); Ladige Mixer (Matsubo Co., Ltd.), and KRC kneader (Kurimoto Iron Works Co.); Bus Co Kneader (Buss Co.); Manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (made by Nippon Steel Works); PCM kneader (made by Ikegai Iron Works Co., Ltd.); triple roll mill, mixing roll mill, kneader (made by Inoue Seisakusho Co., Ltd.); MS pressure press kneader, nider router (Moriyama Seisakusho); Banbury mixer (Kobe Steel) As a pulverizer, a counter jet mill, a micron jet, an inomizer (manufactured by Hosokawa Micron); an IDS type mill, a PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.); a cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); (Manufactured by Nisso Engineering Co., Ltd.); SK Jet Oh Mill (manufactured by Seishin Enterprise Co., Ltd.); kryptron (manufactured by Kawasaki Heavy Industries Co., Ltd.); turbo mill (manufactured by Turbo Kogyo Co., Ltd.). Classifier, Spedic Classifier (manufactured by Seishin Company); Turbo Classifier (manufactured by Nissin Engineering); Micron separator, Turboplex (ATP), TSP separator (manufactured by Hosokawa Micron); ), Dispersion Palator (manufactured by Nippon Pneumatic Kogyo Co., Ltd.); YM micro cut (manufactured by Yaskawa Shoji Co., Ltd.) can be mentioned, and as a sieving device used for sieving coarse particles, etc., Ultrasonic (manufactured by Kanei Sangyo Co., Ltd.); Gyroshifter (Tokuju Kogakusha); Vibrasonic system (Dalton); Soniclean (Shinto Kogyo); Turbo screener (Turbo Kogyo); Micro shifter (Ogino Sangyo); Circular vibrating sieve Is mentioned.
[0258]
When manufacturing the toner of the present invention, it is preferable to use the apparatus system having the above-described configuration for the pulverization step and the classification step.
[0259]
Next, an example of the image forming method of the present invention will be described with reference to FIG.
[0260]
A primary charger 702 charges the surface of the photosensitive drum 1 to a negative polarity, forms a digital latent image by image scanning by exposure 705 with a laser beam, and includes a developing sleeve 704 including a magnetic blade 711 and a magnet 714. The latent image is reversely developed with a dry magnetic toner (one-component magnetic developer) 710 of a developing unit 709. 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 704 by a bias applying unit 712. When the transfer paper P is conveyed and arrives at the transfer portion, the roller transfer means 702 charges the toner on the surface of the photosensitive drum 701 by charging the voltage application means 723 from the back surface of the transfer paper P (the opposite surface to the photosensitive drum side). The image is transferred onto the transfer paper P by the contact transfer means 702. The transfer paper P separated from the photosensitive drum 701 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 707. The toner image may be transferred from the photosensitive drum 701 to the transfer paper P via the intermediate transfer member, or may be transferred to the transfer paper P without passing through the intermediate transfer member.
[0261]
The dry magnetic toner remaining on the photosensitive drum 701 after the transfer process is removed by a cleaning unit 708 having a cleaning blade. When the amount of residual dry magnetic toner is small, the cleaning process can be omitted. The photosensitive drum 701 after cleaning is discharged by erase exposure 706, and the process starting from the charging process by the primary charger 702 is repeated.
[0262]
The photosensitive drum 701 (that is, the electrostatic charge image carrier) has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A nonmagnetic cylindrical developing sleeve 704 that is a toner carrying member rotates so as to advance in the same direction as the surface of the photosensitive drum 701 in the developing portion. Inside the developing sleeve 704, a multi-pole permanent magnet (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The insulating dry magnetic toner 710 in the developing unit 709 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 704 and the magnetic toner. Further, an iron magnetic doctor blade 711 is disposed close to the cylindrical surface (interval 50 μm to 500 μm) and opposed to one magnetic pole position of the multipolar permanent magnet, thereby reducing the thickness of the magnetic toner layer (30 μm to 300 μm) and uniformly, a magnetic toner layer thinner than the gap between the photosensitive drum 701 and the developing sleeve 704 in the developing portion is formed. By adjusting the rotation speed of the developing sleeve 704, the sleeve surface speed is made substantially equal to or close to the speed of the photosensitive drum surface. As the magnetic doctor blade 711, a counter magnetic pole may be formed using a permanent magnet instead of iron. An AC bias or a pulse bias may be applied to the developing sleeve 704 by the bias unit 712 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.
[0263]
When the magnetic toner is transferred in the developing unit, the magnetic toner particles are transferred to the electrostatic image side by the electrostatic force on the surface of the photosensitive drum and the action of an AC bias or a pulse bias.
[0264]
Instead of the magnetic doctor blade 711, an elastic blade made of an elastic material such as silicone rubber may be used to regulate the thickness of the magnetic toner layer by pressing, and the magnetic toner may be applied onto the developing sleeve.
[0265]
FIG. 12 shows an image forming apparatus having a contact charging unit 742 and a corona transfer unit 733 to which a voltage is applied from a bias applying unit 743.
[0266]
FIG. 13 shows an image forming apparatus having a contact charging unit 742 and a contact transfer unit 702.
[0267]
In FIG. 14, reference numeral 702 denotes a transfer roller, which basically has a central core metal 702a and a conductive elastic layer 702b that forms the outer periphery thereof. The transfer roller 702 presses the transfer material against the surface of the photosensitive drum 701 with a pressing force, and rotates with a difference between the peripheral speed and the peripheral speed of the photosensitive drum 701 or a peripheral speed. The transfer material is conveyed between the photosensitive drum 701 and the transfer roller 702 through the guide 744, and a toner image on the photosensitive drum 701 is applied to the transfer roller 702 by applying a bias having a polarity opposite to that of the toner from the transfer bias applying unit 723. Is transferred to the surface side of the transfer material. Next, the transfer material is fed onto the guide 745.
[0268]
The conductive elastic layer 702b has a volume resistance 10 such as polyurethane, ethylene-propylene-diene terpolymer (EPDM) in which a conductive material such as carbon is dispersed.⁶-10^TenMade of Ωcm elastic material.
[0269]
As a preferable transfer process condition, the roller contact pressure is 0.16 × 10 6.^-2~ 24.5 × 10^-2The direct current voltage is ± 0.2 to ± 10 kV at MPa.
[0270]
On the other hand, FIG. 15 shows a contact charging means. In FIG. 15, reference numeral 701 denotes a rotating drum type electrostatic charge image carrier (hereinafter referred to as a photosensitive drum), which has a conductive base layer 701a such as aluminum and the like. The photoconductive layer 701b formed on the outer surface is a basic constituent layer, and is rotated clockwise at a predetermined peripheral speed (process speed) in the drawing.
[0271]
Reference numeral 742 denotes a charging roller, which basically has a central core metal 742a, a conductive elastic layer 742b that forms the outer periphery thereof, and a surface layer 742c. The charging roller 742 is pressed against the surface of the photosensitive drum 701 with a pressing force, and is driven to rotate as the photosensitive drum 701 rotates. A voltage is applied to the charging roller 742 by the bias applying means E, and a bias is applied to the charging roller 742 to charge the surface of the photosensitive drum 701 to a predetermined polarity and 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.
[0272]
As a preferable process condition when using a charging roller, the contact pressure of the roller is 0.49 × 10.^-2~ 98 × 10^-2When using the one in which the AC voltage is superimposed on the DC voltage, the AC voltage is 0.5 to 5 kVpp, the AC frequency is 50 to 5 kHz, the DC voltage is ± 0.2 to ± 1.5 kV, and the DC voltage DC voltage = ± 0.2 to ± 5 kV.
[0273]
The material of the charging roller and charging blade is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) can be applied.
[0274]
FIG. 16 shows a specific example of the process cartridge of the present invention. In the process cartridge, the developing means and the electrostatic charge image carrier are at least integrally formed as a cartridge, and the process cartridge is formed so as to be detachable from the main body of the image forming apparatus (for example, a copying machine or a laser beam printer).
[0275]
FIG. 16 illustrates a process cartridge 750 in which a developing unit 709, a drum-shaped electrostatic charge image carrier (photosensitive drum) 701, a cleaner 708 having a cleaning blade 708a, and a temporary charger (charging roller) 742 are integrated. .
[0276]
In this embodiment, the developing unit 709 includes a magnetic blade 711 and a magnetic toner 710 in a toner container 760, and the magnetic toner 710 is used. At the time of development, the photosensitive drum 701, the developing sleeve 704, and the like are biased by a bias from the bias applying unit. The distance between the photosensitive drum 701 and the developing sleeve 704 is very important in order for a predetermined electric field to be formed between the photosensitive drum 701 and the developing process to be suitably performed.
[0277]
In FIG. 17, the developing unit 709 includes an elastic blade 711 a and a magnetic toner 710 in a toner container 760, and the magnetic toner 710 is used, and at the time of development, the photosensitive drum 1 and the developing sleeve 704 are biased by a bias from the bias applying unit. The distance between the photosensitive drum 1 and the developing sleeve 704 is very important in order that a predetermined electric field is formed between them and the developing process is suitably performed.
[0278]
One specific example of the process cartridge having an injection charging process used in FIG. 18 is shown. This is an example of an image forming apparatus for non-contact development in which magnetic toner is used as the developer and the developer layer on the developer carrier and the image carrier are arranged in non-contact. Reference numeral 801 denotes a rotary drum type OPC photoconductor as an image carrier, which is driven to rotate clockwise (in the direction of the arrow). Reference numeral 802 denotes a charging roller as a contact charging member. The charging roller 802 is disposed in pressure contact with the photoreceptor 801 with a predetermined pressing force against elasticity. n is a charging nip portion which is a nip portion between the photosensitive member 801 and the charging roller 802. In this embodiment, the charging roller 802 is rotationally driven in a facing direction (a direction opposite to the moving direction of the photosensitive member surface) at a charging nip n which is a contact surface with the photosensitive member 801. Further, the conductive fine powder m is applied to the surface of the charging roller 802 so that the coating amount is uniform in a single layer.
[0279]
A DC voltage of −700 V is applied as a charging bias to the cored bar 802a of the charging roller 802 from a charging bias application power source S1 (not shown). In this embodiment, the surface of the photosensitive member 801 is uniformly charged to a potential (−680 V) substantially equal to the voltage applied to the charging roller 802 by the direct injection charging method.
[0280]
A laser beam scanner (exposure device) 803 includes a laser diode, a polygon mirror, and the like. This laser beam scanner outputs laser light (wavelength 740 nm) whose intensity is modulated corresponding to the time-series electric digital pixel signal of the target image information, and scans and exposes the uniformly charged surface of the photosensitive member 1 with the laser light L. To do. An electrostatic latent image corresponding to target image information is formed on the photosensitive member 801 rotated by this scanning exposure.
[0281]
Reference numeral 804 denotes a developing device. The electrostatic latent image on the surface of the photoreceptor 804 is developed as a toner image by the developing device. The developing device 804 of the embodiment is a non-contact type reversal developing device using an insulating negatively chargeable magnetic toner. The magnetic toner 4d contains magnetic toner particles (t) and conductive fine powder (m).
[0282]
Reference numeral 804a denotes a non-magnetic developing sleeve having a diameter of 16 mm that includes a magnet roll 804b as a developer carrying member. The developing sleeve 804a is arranged to face the photosensitive member 1 with a separation distance of 320 μm, and the developing portion (developing region portion) a that is the facing portion of the photosensitive member 801 is arranged in the order of the rotation direction of the photosensitive member 801. And rotated at a peripheral speed ratio of 120% of the peripheral speed of the photosensitive member 801 in the direction.
[0283]
A magnetic toner 804d is coated on the developing sleeve 804a in a thin layer by an elastic blade 804c. The magnetic toner 804d is given a charge while the layer thickness on the developing sleeve 804a is regulated by the elastic blade 804c.
[0284]
The magnetic toner 804d coated on the developing sleeve 804a is conveyed to the photosensitive portion 801 and the developing portion a which is the opposite portion of the developing sleeve 804a as the developing sleeve 804a rotates.
[0285]
A developing bias voltage is applied to the developing sleeve 804a by a developing bias applying power source S2. The development bias voltage is a DC voltage of −420 V, a frequency of 1500 Hz, a peak-to-peak voltage of 1600 V (electric field strength of 5 × 10⁶A one-component jumping development is performed between the developing sleeve 804a and the photosensitive member 801 using a superposition of a rectangular alternating voltage of V / m). In the present invention, the conductive fine powder m is not only applied to the charging roller, but may be externally added to the magnetic toner.
[0286]
Due to the presence of the conductive fine powder m, close contact and contact resistance of the charging roller 802 to the photosensitive member 801 can be maintained, so that the charging roller 802 can perform direct injection charging of the photosensitive member 801.
[0287]
The charging roller 802 comes into close contact with the photosensitive member 801 through the conductive fine powder m, and the conductive fine powder m rubs the surface of the photosensitive member 801 without any gap. As a result, the charging of the photosensitive member 801 by the charging roller 802 can be dominated by stable and safe direct injection charging without using a discharge phenomenon, and high charging that cannot be obtained by conventional roller charging or the like. Efficiency is obtained. Accordingly, a potential substantially equal to the voltage applied to the charging roller 802 can be applied to the photoconductor 801.
[0288]
The toner image on the photosensitive drum 801 is transferred to the transfer material P by the transfer roller 805 to which the transfer bias is applied by the transfer bias application power source S3 at the transfer portion b. The transfer roller 805 presses the transfer material P at a linear pressure of 1 to 80 g / cm during transfer.
[0289]
【Example】
Although the basic configuration and features of the present invention have been described above, the present invention will be specifically described below based on examples. However, this does not limit the embodiment of the present invention. The number of parts in the examples is part by mass.
[0290]
Table 1 shows resins used in Examples, Table 2 shows waxes, and Table 3 shows magnetic iron oxide particles. The styrene resin was synthesized by solution polymerization or suspension polymerization, and the polyester resin was synthesized by a dehydration condensation method. A method for producing magnetic iron oxide particles will be described below.
[0291]
・Production example 1 of magnetic iron oxide particles
In the ferrous sulfate solution, Fe²⁺After mixing 0.95 equivalent sodium hydroxide aqueous solution with respect to Fe (OH)₂A ferrous salt aqueous solution containing was produced. Then, sodium silicate was added so that it might become 1.0 mass% in conversion of a silicon element with respect to an iron element. Then Fe (OH)₂Magnetic iron oxide particles containing silicon element were produced by aerating air at a temperature of 90 ° C. to an aqueous ferrous salt solution containing and oxidizing the solution under the condition of pH 6 to 7.5. Further, an aqueous sodium hydroxide solution in which 0.1% by mass of sodium silicate was dissolved (in terms of silicon element with respect to iron element) was added to this suspension.²⁺1.05 equivalents was added to the mixture, and further heated at a temperature of 90 ° C., an oxidation reaction was performed under conditions of pH 8 to 11.5 to produce magnetic iron oxide particles containing silicon element. The produced magnetic iron oxide particles were washed, filtered and dried by a conventional method.
[0292]
Since the primary particles of the obtained magnetic iron oxide particles are aggregated to form aggregates, a compressive force and shear are applied to the aggregates of magnetic iron oxide particles using a mix muller (manufactured by Shinto Kogyo Co., Ltd.). The magnetic iron oxide particles 1 having the characteristics shown in Table 3 are obtained by applying a force to break up the aggregates to make the magnetic iron oxide particles primary particles and smooth the surface of the magnetic iron oxide particles. Obtained. The average particle diameter of the magnetic iron oxide particles was 0.21 μm. The surface of the magnetic iron oxide particle 1 was formed of iron oxide and silicon oxide.
[0293]
・Production example 2 of magnetic iron oxide particles
Similar to Production Example 1, magnetic iron oxide particles 2 of Production Example 2 were obtained by changing the amount of silicon element. The surface of the magnetic iron oxide particles 2 was formed of iron oxide and silicon oxide.
[0294]
・Production examples 3 and 4 of magnetic iron oxide particles
Before the filtration step of the magnetic iron oxide particles obtained in Production Example 2, a predetermined amount of aluminum sulfate is added to the slurry liquid, the pH is adjusted to a range of 6 to 8, and aluminum hydroxide is used as the magnetic iron oxide particles. Surface treatment was performed to obtain magnetic iron oxide particles 3 and 4 of Production Examples 3 and 4. The magnetic iron oxides of Production Examples 3 and 4 were subjected to consolidation crushing treatment by a mix muller as in Production Example 1. The surfaces of the magnetic iron oxide particles 3 and 4 were formed of iron oxide, silicon oxide, aluminum oxide, and aluminum hydroxide.
[0295]
・Production examples 5 and 6 of magnetic iron oxide particles
A predetermined total silicon content was charged at the time of the first stage reaction in Production Example 1, and the sodium hydroxide aqueous solution to be charged was further added to Fe.²⁺By changing the pH adjustment to an amount exceeding 1 equivalent, the magnetic iron oxide particles 5 and 6 of Production Examples 5 and 6 were obtained. The surfaces of the magnetic iron oxide particles 5 and 6 were formed of iron oxide and silicon oxide.
[0296]
・Production example 7 of magnetic iron oxide particles
In a ferrous sulfate aqueous solution, after adding sodium silicate so that the content of silicon element is 1.8% with respect to iron element, 1.0 to 1.1 equivalent of water with respect to iron ion Mixed with alkali oxide aqueous solution, Fe (OH)₂A ferrous salt aqueous solution containing was produced. Next, while maintaining the pH of the aqueous solution at 9, air was vented at a temperature of 85 ° C. to carry out an oxidation reaction, thereby producing magnetic iron oxide particles containing silicon element. Furthermore, after adding ferrous sulfate aqueous solution so that it might become 1.1 equivalent with respect to the initial alkali amount (sodium component of sodium silicate, and sodium component of alkali hydroxide) to this suspension, pH of a solution Was maintained at 8, and the oxidation reaction was promoted while blowing air, and the pH was adjusted to the weak alkali side at the end of the oxidation reaction to obtain magnetic iron oxide particles.
[0297]
The produced magnetic iron oxide particles were washed, filtered, and dried by a conventional method, and then the agglomerated magnetic iron oxide particles were subjected to ordinary crushing treatment to obtain magnetic iron oxide particles 7. The surface of the magnetic iron oxide particles 7 was formed of iron oxide and silicon oxide.
[0298]
Example 1
・ Binder resin A 100 parts
・ 90 parts of magnetic iron oxide particles 3
・ Wax c 4 parts
・ Azo-based iron complex compound A 2 parts
The above materials were premixed with a Henschel mixer and then melt-kneaded with a twin-screw kneading extruder set at 130 ° C.
[0299]
The obtained kneaded product was cooled and coarsely pulverized to 1 mm or less with a cutter mill to obtain a coarsely pulverized product. The obtained coarsely pulverized product is finely pulverized by a mechanical pulverizer 301 shown in FIG. 2, and the obtained finely pulverized product is classified using a multi-division classifier shown in FIG. 2, and has a weight average particle size of 6.5 μm. Magnetic toner particles were obtained. In this embodiment, the crushed surfaces of the rotor 314 and the stator 310 of the mechanical pulverizer 301 are subjected to wear resistance treatment by nitriding. The surface roughness after the treatment was 1.1 μm for the center line roughness Ra, 20.6 μm for the maximum roughness Ry, and 12.3 μm for the ten-point average roughness. The rotor 314 was ground at a peripheral speed of 117 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 42 ° C.
[0300]
100 parts of the magnetic toner particles obtained were hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone, and had a methanol wettability of 80% and a BET specific surface area of 120 m.²/ G of negatively chargeable hydrophobic silica fine powder of 1.2 parts and 1.0 part of strontium titanate in an Henschel mixer FM10C / l (manufactured by Mitsui Mining Co., Ltd.), the apparent volume filling ratio of the dry magnetic toner is 12 %, The magnetic toner is filled so that the rotation speed is 45.00 s using the Y0 blade and S0 blade shown in FIG.^-1For 1 minute, then continue for 50.00s^-1The magnetic toner No. was stirred for 2 minutes. 1 was prepared.
[0301]
The toner internal formulation, pulverization conditions and physical properties are shown in Table 4. The relationship between the circularity of 1 and the average particle diameter is shown in FIG. 20, and the relationship between the weight average diameter X and the half-value width with respect to the peak particle size is shown in FIG.
[0302]
Magnetic toner No. 1 was modified to a print speed of 1.5 times corresponding to a process speed of 235 mm / sec with a commercially available LBP printer (LBP-930, manufactured by Canon Inc.) in the form of FIG. 13, and normal temperature and humidity (23 ° C., 65% RH), low-temperature and low-humidity (15 ° C., 10% RH) environment, and high-temperature and high-humidity (30 ° C., 80% RH) environment, 15,000 sheets of print tests were performed.
[0303]
The image density was measured with a Macbeth densitometer (manufactured by Macbeth) using an SPI filter to measure reflection density, and a 5 mm square image was measured. The fog is measured using a reflection densitometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.). The worst value of the white background reflection density after image formation is Ds, and the reflection average density of the transfer material before image formation is Dr. The fog was evaluated using Ds-Dr as the fog amount. The smaller the number, the better the fog suppression.
[0304]
These evaluations were performed at the initial stage after 15000 sheets were left outside the apparatus for a day.
[0305]
Regarding the evaluation of the transfer efficiency, the fluctuation in transferability at the initial stage and after the endurance of 10,000 sheets was evaluated in a commercially available LBP printer (LBP-950, manufactured by Canon Inc.) in an environment of 23 ° C. and 65% RH. 75g / cm for transfer paper²Plain paper was used. Transferability is calculated from the numerical value obtained by subtracting the transfer residual toner and the pre-transfer toner on a solid black 6PC photoconductor with a tape and stripping it on the paper, and subtracting the Macbeth density of the tape only from the tape. And evaluated.
[0306]
For the evaluation of magnetic toner consumption and line width, Canon laser beam printer LBP-1760 was modified from 16 sheets / min to 24 sheets / min, using a normal temperature and humidity environment (23 ° C., 65% RH), 1000 images are printed out, and a 10-dot horizontal line pattern of 600 dpi is set so that the latent image line width is about 420 μm, and 5000 images with a printing rate of 4% are output on A4 size paper. The amount of consumption was determined from the change in the amount of magnetic toner. Further, a solid black image was output, and the image density at this time was confirmed.
[0307]
Further, a 10-dot horizontal line pattern latent image (latent image line width of about 420 μm) of 600 dpi was written at 1 cm intervals, developed, and transferred and fixed on an OHP made of PET. Using the surface roughness meter Surfcoder SE-30H (manufactured by Kosaka Laboratories), the obtained horizontal line pattern image is obtained as a surface roughness profile indicating how the toner is applied to the horizontal line, and the line width is obtained from the width of this profile. It was. When the line width is slightly thicker than the latent image line width, an image with the highest sharpness can be obtained, and as the line width becomes narrower than the latent image line width, the reproducibility of the thin line decreases.
[0308]
Magnetic toner with high image density, proper line width and low toner consumption is preferred. Magnetic toner with low image density and low toner consumption, or magnetic toner with low line density and low toner consumption This is not a preferred form.
[0309]
For the evaluation of image quality, an isolated 1-dot pattern was drawn using the above-described image-drawing tester, and the dot reproducibility was evaluated by observing the image with an optical microscope.
A: There is no protrusion of magnetic toner from the latent image, and the dots are completely reproduced.
B: There are some protrusions of magnetic toner from the latent image.
C: There is a slight protrusion of magnetic toner from the latent image
D: Magnetic toner sticks out of the latent image
[0310]
For the evaluation of tailing, a pattern of about 20 cm in length, in which a 4-dot horizontal line was printed in a 175-dot space, was drawn using the above-described image-drawing tester, and was visually observed on 50 of the lines. The number of lines that were tailed was counted.
A: No occurrence
B: 2 or less
C: 3-6
D: 7-14
E: 15 or more
[0311]
The evaluation results are shown in Tables 8-12.
[0312]
Example 2
In the same manner as in Example 1, the magnetic toner no. 2 was produced. However, the rotor 314 was ground at a peripheral speed of 125 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 37 ° C. The obtained magnetic toner No. The physical property values of No. 2 are shown in Table 4. The relationship between the degree of circularity and the average particle size is shown in FIG. 20, and the relationship between the weight average diameter X and the half-value width with respect to the peak particle size is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0313]
Example 3
In the same manner as in Example 1, the magnetic toner no. 3 was produced. However, the rotor 314 was ground at a peripheral speed of 150 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 53 ° C. The obtained magnetic toner No. The physical property values of No. 3 are shown in Table 4. The relationship between the circularity of 3 and the average particle diameter is shown in FIG. 20, and the relationship between the weight average diameter X and the half width with respect to the peak particle size is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0314]
Example 4
In the same manner as in Example 1, the magnetic toner no. 4 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 114 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 45 ° C. The obtained magnetic toner No. The physical property values of No. 4 are shown in Table 4. FIG. 21 shows the relationship between the circularity of 4 and the average particle size, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0315]
Example 5
In the same manner as in Example 1, the magnetic toner no. 5 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 115 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 40 ° C. The obtained magnetic toner No. The physical properties of Table 5 are shown in Table 4. FIG. 20 shows the relationship between the circularity of 5 and the average particle size, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0316]
Example 6
In the same manner as in Example 1, the magnetic toner no. 6 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 144 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 55 ° C. The obtained magnetic toner No. The physical property values of No. 6 are shown in Table 4. FIG. 21 shows the relationship between the circularity of 6 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the full width at half maximum with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0317]
Example 7
In the same manner as in Example 1, the magnetic toner no. 7 was produced. However, medium pulverization was performed by a mechanical pulverizer 301 shown in FIG. 2 before the pulverization step. The grinding conditions at this time were the same as those in the grinding process. However, the gap between the rotor 314 and the stator 310 was pulverized to 2.0 mm. Thereafter, the rotor 314 was ground at a peripheral speed of 144 m / s, and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 55 ° C. The obtained magnetic toner No. The physical property values of No. 7 are shown in Table 4. FIG. 20 shows the relationship between the circularity of 7 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the full width at half maximum with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0318]
Example 8
In the same manner as in Example 7, the magnetic toner no. 8 was produced. The obtained magnetic toner No. The physical property values of No. 8 are shown in Table 4. FIG. 20 shows the relationship between the circularity of 8 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the full width at half maximum with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0319]
Example 9
In the same manner as in Example 7, the magnetic toner no. 9 was produced. The obtained magnetic toner No. The physical property values of No. 9 are shown in Table 4. FIG. 21 shows the relationship between the circularity of 9 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the full width at half maximum with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0320]
Example 10
In the same manner as in Example 7, the magnetic toner no. 10 was produced. The obtained magnetic toner No. The physical property values of No. 10 are shown in Table 5. FIG. 21 shows the relationship between the degree of circularity of 10 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0321]
Example 11
In the same manner as in Example 1, the magnetic toner no. 11 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 90 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 30 ° C. The obtained magnetic toner No. The physical property values of No. 11 are shown in Table 5. 11 shows the relationship between the circularity of 11 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0322]
Example 12
In the same manner as in Example 1, the magnetic toner no. 12 was produced. However, the rotor 314 was ground at a peripheral speed of 120 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 50 ° C. The obtained magnetic toner No. The physical property values of No. 12 are shown in Table 5. FIG. 20 shows the relationship between the degree of circularity of 12 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0323]
Example 13
In the same manner as in Example 1, the magnetic toner no. 13 was produced. However, the surface roughness and centerline roughness Ra were 1.7 μm, the maximum roughness Ry was 35.6 μm, and the ten-point average roughness was 21.3 μm. The rotor 314 was ground at a peripheral speed of 155 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 46 ° C. The obtained magnetic toner No. The physical properties of No. 13 are shown in Table 5. FIG. 20 shows the relationship between the circularity of 13 and the average particle size, and FIG. 22 shows the relationship between the weight average diameter X and the half-value width with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0324]
Example 14
In the same manner as in Example 1, the magnetic toner no. 14 was produced. However, the rotor 314 was ground at a peripheral speed of 135 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 33 ° C. The obtained magnetic toner No. The physical properties of No. 14 are shown in Table 5. The relationship between the circularity of 14 and the average particle diameter is shown in FIG. 21, and the relationship between the weight average diameter X and the half-value width with respect to the peak particle size is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0325]
Example 15
In the same manner as in Example 1, the magnetic toner no. 15 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 115 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 48 ° C. The obtained magnetic toner No. The physical property values of No. 15 are shown in Table 5. FIG. 21 shows the relationship between the circularity of 15 and the average particle diameter, and FIG. 22 shows the relationship between the weight average diameter X and the full width at half maximum with respect to the peak particle size. Tables 8 to 12 show the results of the same tests as in Example 1.
[0326]
Comparative Example 1
Comparative magnetic toner (i) was prepared in the same manner as in Example 1 with the formulation shown in Table 5. However, the rotor and stator were mirror-finished and then subjected to wear resistance treatment by nitriding. The roughness of the ground surface after the treatment was 0.9 μm for the center line roughness Ra, 9.0 μm for the maximum roughness Ry, and 6.4 μm for the 10-point average roughness. The rotor 314 was ground at a peripheral speed of 150 m / s, and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 53 ° C. The physical property values of the obtained comparative magnetic toner (i) are shown in Table 5, the relationship between the circularity and the average particle diameter of the comparative magnetic toner (i) is shown in FIG. 20, and the half-value width with respect to the weight average diameter X and the peak particle size is shown. The relationship is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0327]
Comparative Example 2
Comparative magnetic toner (ii) was prepared in the same manner as in Example 1 with the formulation shown in Table 5. However, the rotor and stator were blasted and then subjected to wear resistance by nitriding. The roughness of the ground surface after the treatment is center line roughness Ra of 3.2 μm, maximum roughness Ry of 43.5 μm, ten-point average roughness of 35.4 μm, and the peripheral speed of rotor 314 is 90 m / s. Then, the gap between the rotor 314 and the stator 310 was pulverized to 1.0 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 31 ° C. The physical property values of the obtained comparative magnetic toner (ii) are shown in Table 5, the relationship between the circularity and the average particle diameter of the comparative magnetic toner (ii) is shown in FIG. 21, and the half-value width with respect to the weight average diameter X and the peak particle size is shown. The relationship is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0328]
Comparative Example 3
Comparative magnetic toner (iii) was prepared according to the formulation shown in Table 5. In the pulverization step, the pulverized powder was pulverized with a fine pulverizer using collision airflow pulverization, and the obtained finely pulverized powder was classified using a multi-division classifier utilizing the Coanda effect. The physical property values of the obtained comparative magnetic toner (iii) are shown in Table 5, the relationship between the circularity and the average particle diameter of the comparative magnetic toner (iii) is shown in FIG. 20, and the half-value width with respect to the weight average diameter X and the peak particle size is shown. The relationship is shown in FIG. Tables 8 to 12 show the results of the same tests as in Example 1.
[0329]
Comparative Example 4
Comparative magnetic toner (iv) was prepared according to the formulation shown in Table 5. The pulverization process is performed by a fine pulverizer using a collision type airflow pulverization, and the obtained fine pulverized powder is classified using a multi-division classifier utilizing the Coanda effect. Modified. Table 5 shows the physical properties of the obtained comparative magnetic toner (iv). Tables 8 to 12 show the results of the same tests as in Example 1.
[0330]
Examples 16-20
The magnetic toner No. used in Examples 1, 2, 12, 13, and 15 was used. 1, 2, 12, 13 and 15 were used, and the cartridge used for a commercially available LBP printer (LBP-250, manufactured by Canon Inc.) was remodeled into the cartridge having the injection charging process described in FIG. The image was evaluated. The contents of the remodeling are as follows: The charging roller is uniformly coated with conductive fine powder of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm, and the charging roller is charged with a DC voltage of −700 V from the charging bias application power source S1. Applied as a bias.
[0331]
In this embodiment, the surface of the OPC photosensitive member 1 was uniformly charged by a direct injection charging method to a potential (−680 V) substantially equal to the voltage applied to the charging roller 2. The development bias voltage is a DC voltage of −420 V, a frequency of 1500 Hz, a peak-to-peak voltage of 1600 V (electric field strength of 5 × 10⁶One-component jumping development was performed between the developing sleeve 4a and the OPC photosensitive member 1 using a superposed voltage of a rectangular alternating voltage of V / m).
[0332]
Using this cartridge, a commercially available LBP printer (LBP-250, manufactured by Canon Inc.) was remodeled so as to have a process speed of 120 mm / sec, and toner consumption, image density, line width, dot reproducibility, as in Example 1, The tailing was evaluated. The results are shown in Table 13.
[0333]
[Table 1]

[0334]
[Table 2]

[0335]
[Table 3]

[0336]
Embedded image

[0337]
[Table 4]

[0338]
[Table 5]

[0339]
[Table 6]

[0340]
[Table 7]

[0341]
[Table 8]

[0342]
[Table 9]

[0343]
[Table 10]

[0344]
[Table 11]

[0345]
[Table 12]

[0346]
[Table 13]

[0347]
Example 21
・ Binder resin B 100 parts
・ 90 parts of magnetic iron oxide particles 3
・ Wax c 4 parts
・ Azo-based iron complex compound A 2 parts
The above materials were premixed with a Henschel mixer and then melt-kneaded with a twin-screw kneading extruder set at 130 ° C.
[0348]
The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a cutter mill to obtain a coarsely pulverized material as a powder raw material for toner production. The obtained powder raw material is finely pulverized by a mechanical pulverizer 301 shown in FIG. 2, and the obtained finely pulverized product is classified using a multi-division classifier shown in FIG. 2 to obtain a weight average particle diameter of 6.5 μm. Magnetic toner particles were obtained. In this example, the surface roughness of the pulverized surfaces of the rotor 314 and the stator 310 of the mechanical pulverizer 301 is roughened to obtain a center line roughness Ra = 5.9 μm and a maximum roughness Ry =. The wear resistance treatment was performed by nitriding with 32.4 μm and 10-point average roughness = 21.4 μm. Further, the rotor 314 was ground at a peripheral speed of 117 m / s, and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 42 ° C.
[0349]
100 parts of the magnetic toner particles obtained were hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone, and had a methanol wettability of 80% and a BET specific surface area of 120 m.²/ G of hydrophobic silica fine powder 1.2 parts and 1.0 part of strontium titanate were externally added and mixed to obtain magnetic toner No. 16 was prepared.
[0350]
The toner internal formulation, pulverization conditions, and physical property values are shown in Tables 14 and 15, and the magnetic toner no. The relationship between the circularity of 16 and the average particle diameter is shown in FIG.
[0351]
Magnetic toner No. 16 was modified to a 1.5 times printing speed with a commercially available LBP printer (LBP-930, manufactured by Canon Inc.) in the form of FIG. 13, with an environment of 23 ° C. and 65% RH, and 15 ° C. and 10% RH. A print test of 15,000 sheets was performed in an environment and an environment of 30 ° C. and 80% RH. The evaluation results are shown in Tables 16-18.
[0352]
The image density was measured with a Macbeth densitometer (manufactured by Macbeth) using an SPI filter to measure reflection density, and a 5 mm square image was measured. The fog is measured using a reflection densitometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.). The worst value of the white background reflection density after image formation is Ds, and the reflection average density of the transfer material before image formation is Dr. The fog was evaluated using Ds-Dr as the fog amount. The smaller the number, the better the fog suppression.
[0353]
These evaluations were performed at the initial stage after 15000 sheets were left outside the apparatus for a day.
[0354]
Regarding the evaluation of the transfer efficiency, the fluctuation in transferability at the initial stage and after the endurance of 10,000 sheets was evaluated with a commercially available LBP printer (LBP-930, manufactured by Canon Inc.) in an environment of 23 ° C. and 65% RH. 75g / cm for transfer paper²Plain paper was used. Transferability is calculated from the numerical value obtained by subtracting the transfer residual toner on the solid black photoconductor and the pre-transfer toner with a polyester tape and stripping it off, then subtracting the Macbeth density of the tape only on the tape. And evaluated. The evaluation results are shown in Table 19.
[0355]
Example 22
In the same manner as in Example 21, the magnetic toner no. 17 was produced. However, the rotor 314 was ground at a peripheral speed of 125 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 37 ° C. The obtained magnetic toner No. The physical property values of No. 17 are shown in Tables 14 and 15. The relationship between the circularity of 17 and the average particle size is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0356]
Example 23
In the same manner as in Example 21, the magnetic toner no. 18 was produced. However, the rotor 314 was ground at a peripheral speed of 150 m / s and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 63 ° C. The obtained magnetic toner No. The physical property values of No. 18 are shown in Tables 14 and 15, and the magnetic toner No. The relationship between the circularity of 18 and the average particle diameter is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0357]
Example 24
In the same manner as in Example 21, the magnetic toner no. 19 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 114 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 45 ° C. The obtained magnetic toner No. The physical property values of No. 19 are shown in Tables 14 and 15. The relationship between the circularity of 19 and the average particle diameter is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0358]
Example 25
In the same manner as in Example 21, the magnetic toner no. 20 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 115 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 40 ° C. The obtained magnetic toner No. The physical property values of No. 20 are shown in Tables 14 and 15. The relationship between the circularity of 20 and the average particle diameter is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0359]
Example 26
In the same manner as in Example 21, the magnetic toner no. 21 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 144 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 60 ° C. The obtained magnetic toner No. Table 14 and Table 15 show the physical property values of No. 21. The relationship between the circularity of 21 and the average particle diameter is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0360]
Example 27
In the same manner as in Example 21, the magnetic toner no. 22 was produced. However, the pulverization was performed by setting the peripheral speed of the rotor 314 to 90 m / s and the gap between the rotor 314 and the stator 310 to 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 30 ° C. The obtained magnetic toner No. The physical property values of No. 22 are shown in Tables 14 and 15. The relationship between the circularity of 22 and the average particle diameter is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0361]
Comparative Example 5
A comparative magnetic toner (v) was prepared in the same manner as in Example 21 with the formulation shown in Table 14. However, the surface roughness of the pulverized surface was center line roughness Ra = 1.8 μm, maximum roughness Ry = 13.5 μm, ten-point average roughness = 9.8 μm, and the wear resistance treatment was performed by nitriding. The rotor 314 was ground at a peripheral speed of 150 m / s, and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 63 ° C. The physical property values of the obtained comparative magnetic toner (v) are shown in Tables 14 and 15, and the relationship between the circularity and the average particle diameter of the comparative magnetic toner (v) is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0362]
Comparative Example 6
Comparative magnetic toner (vi) was prepared in the same manner as in Example 21 with the formulation shown in Table 14. However, the surface roughness of the pulverized surface was center line roughness Ra = 12.3 μm, maximum roughness Ry = 70.8 μm, ten-point average roughness = 41.3 μm, and wear resistance treatment was performed by nitriding. The rotor 314 was ground at a peripheral speed of 90 m / s, and the gap between the rotor 314 and the stator 310 was 1.3 mm. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 31 ° C. The physical property values of the obtained comparative magnetic toner (vi) are shown in Tables 14 and 15, and the relationship between the circularity and the average particle diameter of the comparative magnetic toner (vi) is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0363]
Comparative Example 7
A comparative magnetic toner (vii) was prepared according to the formulation shown in Table 14. In the pulverization step, the pulverized powder was pulverized with a fine pulverizer using collision airflow pulverization, and the obtained finely pulverized powder was classified using a multi-division classifier utilizing the Coanda effect. The physical property values of the obtained comparative magnetic toner (vii) are shown in Tables 14 and 15, and the relationship between the circularity and the average particle diameter of the comparative magnetic toner (vii) is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0364]
Comparative Example 8
A comparative magnetic toner (viii) was prepared according to the formulation shown in Table 14. The pulverization process is performed by a fine pulverizer using a collision type airflow pulverization, and the obtained fine pulverized powder is classified using a multi-division classifier utilizing the Coanda effect. After classification, the shape and surface properties of the particles are determined by a hybridizer. Modified. The physical property values of the obtained comparative magnetic toner (viii) are shown in Tables 14 and 15, and the relationship between the circularity and the average particle diameter of the comparative magnetic toner (viii) is shown in FIG. Moreover, the result of having done the test similar to Example 21 is shown to Tables 16-19.
[0365]
[Table 14]

[0366]
[Table 15]

[0367]
[Table 16]

[0368]
[Table 17]

[0369]
[Table 18]

[0370]
[Table 19]

[0371]
【The invention's effect】
According to the present invention, toner having a specific number of magnetic iron oxides is prevented from adhering to a fixing member regardless of the structure of the fixing device, and high image quality can be obtained even when used under high and low humidity conditions. The transfer efficiency can be obtained stably, without causing image defects over time, and without impairing fixability.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining an example of a toner production method of the present invention.
FIG. 2 is a schematic view showing a specific example of an apparatus system for carrying out an example of the toner manufacturing method of the present invention.
FIG. 3 is a schematic cross-sectional view of an example of a mechanical pulverizer used in the toner pulverization step of the present invention.
4 is a schematic cross-sectional view taken along a D-D ′ plane in FIG. 3;
5 is a perspective view of the rotor shown in FIG. 3. FIG.
FIG. 6 is a schematic cross-sectional view of a multi-split airflow classifier used in the toner classification process of the present invention.
FIG. 7 is a flowchart for explaining a conventional manufacturing method.
FIG. 8 is a system diagram showing a conventional manufacturing method.
FIG. 9 is a schematic sectional view of a conventional collision-type airflow crusher.
FIG. 10 is a schematic sectional view of a multi-split airflow classifier used for a conventional second classifying means.
FIG. 11 is a schematic view showing an example of an image forming apparatus suitable for image formation using the magnetic toner of the present invention.
FIG. 12 is a schematic diagram illustrating an example of a suitable image forming apparatus.
FIG. 13 is a schematic diagram illustrating another example of a suitable image forming apparatus.
FIG. 14 is a diagram schematically showing a transfer device.
FIG. 15 is a view schematically showing a charging roller.
FIG. 16 is an explanatory diagram showing an example of a process cartridge according to the present invention.
FIG. 17 is an explanatory view showing an example of a process cartridge using the elastic blade of the present invention.
FIG. 18 is an explanatory view showing an example of a process cartridge having an injection charging process used in an embodiment of the present invention.
FIG. 19 is an explanatory diagram of an apparatus used for toner charge amount measurement.
FIG. 20 is a diagram for explaining the relationship between circularity and average particle diameter.
FIG. 21 is a diagram for explaining the relationship between circularity and average particle diameter.
FIG. 22 is a diagram for explaining the relationship between the weight average diameter X and the half width Y with respect to the peak particle size.
FIG. 23 is data of particle size distribution representing the relationship between the weight average diameter X and the half width Y with respect to the peak particle size.
FIG. 24 is an explanatory diagram of a stirring blade used for addition and mixing used in an example of the present invention.
FIG. 25 is a diagram for explaining the relationship between circularity and average particle diameter.
FIG. 26 is a diagram for explaining the relationship between circularity and average particle diameter.
[Explanation of symbols]
1 Multi-division classifier
2 Second metering feeder
3 Vibration feeder
4,5,6 collection cyclone
11, 12, 13 outlet
11a, 12a, 13a discharge conduit
14,15 Intake tube
16 Raw material supply nozzle
17, 18 Classification edge
19 Inlet edge
20 First gas introduction adjusting means
21 Second gas introduction control means
22, 23 side wall
24,25 Classification edge block
26 Coanda Block
27 Left block
28, 29 Static pressure gauge
30 classification area
32 classification room
40 Raw material supply port
41 High pressure air nozzle
42 Raw material powder introduction nozzle
122 First classifier
123 Collection Cyclone
124 Second metering feeder
125 Vibrating feeder
127 Multi-division classifier (second classifier)
128 Airflow crusher
129,130,131 Collection cyclone
135 Injection feeder
141, 142 side wall
143,144 Classification edge block
145 Coanda Block
146,147 Classification edge
148, 149 Raw material supply pipe
150 classification room upper wall
151 Inlet edge
153,153 Intake tube
154,155 Gas introduction adjusting means
156,157 Static pressure gauge
158, 159, 160 outlet
161 High-pressure gas supply nozzle
162 Accelerating tube
163 Acceleration tube exit
164 Colliding member
165 Raw material supply port
166 Colliding surface
167 Pulverized product outlet
212 Swirl chamber
219 pipe
220 Distributor
222 Bug Filter
224 Suction filter
229 Collection Cyclone
301 mechanical crusher
302 Powder outlet
310 Stator
311 Powder inlet
312 Rotating shaft
313 casing
314 Rotor
315 First metering feeder
316 jacket
317 Cooling water supply port
318 Cooling water outlet
320 back room
321 Cold air generating means
331 Third metering machine
701 Latent image carrier (photosensitive member)
702 Transfer roller
702a cored bar
702b Conductive elastic layer
704 Development sleeve (developer carrier)
705 exposure
709 Developer
711 Magnetic blade
723 constant voltage power supply
742 Charging roller

Claims (18)

In a dry magnetic toner having magnetic toner particles having at least a binder resin, magnetic iron oxide particles and wax, and inorganic fine powder and hydrophobic inorganic fine powder,
The magnetic toner particles are obtained by melt-kneading a mixture containing at least a binder resin, magnetic iron oxide particles and wax, cooling the kneaded product, coarsely pulverizing the cooled product, and obtaining the coarsely pulverized product with a mechanical pulverizer. Obtained by pulverizing with
The inorganic fine powder and the hydrophobic inorganic fine powder are used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the magnetic toner.
The inorganic fine powder is strontium titanate, the hydrophobic inorganic fine powder is a hydrophobic silica fine powder,
100 to 350 free magnetic iron oxide particles are present per 10,000 magnetic toner particles,
The weight average particle diameter of the magnetic toner is 5 μm to 12 μm, and the circularity of the particles constituting the magnetic toner is a circularity measured by the following measurement method,
Measuring method: [Method for measuring the circularity of particles constituting the magnetic toner: 0.1 to 0.5 ml of a surfactant as a dispersing agent is added to 100 to 150 ml of water from which impurities in the container have been previously removed, and then the magnetic toner is added. 0.1 to 0.5 g is added, and the suspension in which the magnetic toner is dispersed is irradiated with ultrasonic waves (50 kHz, 120 W) for 1 to 3 minutes, and the dispersion concentration is set to 1.2 to 2 million pieces / μl. Using a flow type particle image measuring apparatus, the circularity distribution of particles having a circle-equivalent diameter of 0.60 μm or more and less than 159.21 μm is measured. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the following circularity calculation formula. ]
In the particles of 3 μm or more constituting the magnetic toner, 90% by number or more of particles having a circularity a of 0.900 or more obtained from the following formula (1) based on the number,
Circularity a = L ₀ / L (1)
[In the formula, L ₀ represents the circumference of a circle having the same projected area as the particle image, and L represents the circumference of the particle image. ]
A) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (2):
Cut rate Z ≦ 5.3 × X (2)
[However, the cut rate Z is expressed by the equation (3) when the particle concentration A (number / μl) of all measured particles and the measured particle concentration B (number / μl) of the equivalent circle diameter of 3 μm or more.
Z = (1-B / A) × 100 (3)]
In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (4);
Number-based cumulative value Y ≧ exp5.51 × X ^−0.645 of particles having a circularity of 0.950 or more (4)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
Or
b) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (5):
Cut rate Z> 5.3 × X (5)
In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (6);
Number-based cumulative value Y ≧ exp5.37 × X ^−0.545 of particles having a circularity of 0.950 or more (6)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
A dry magnetic toner.   The dry magnetic toner according to claim 1, wherein the magnetic iron oxide particles are contained in an amount of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin.   2. The dry magnetism according to claim 1, wherein the magnetic iron oxide particles have Si atoms derived from silicon oxide on the surface, and the Fe / Si atomic ratio on the outermost surface is 1.2 to 7.0. toner.   The dry magnetic toner according to any one of claims 1 to 3, wherein the magnetic iron oxide particles have a smoothness of 0.3 to 0.8. The dry magnetic toner according to claim 1, wherein the specific surface area of the magnetic iron oxide particles is 15.0 m ² / g or less.   6. The dry process according to claim 1, wherein the magnetic iron oxide particles contain 0.01 to 2.0% by mass of aluminum oxide and aluminum hydroxide in terms of aluminum element. Magnetic toner.   The magnetic iron oxide particles have Al atoms derived from aluminum oxide and aluminum hydroxide on the surface, and the Fe / Al atomic ratio on the outermost surface is 0.3 to 10.0. The dry magnetic toner described in 1. The dry magnetic toner according to any one of claims 1 to 7 , wherein the magnetic toner contains 0.2 to 20 parts by mass of the wax with respect to 100 parts by mass of the binder resin. The dry magnetic toner according to claim 8 , wherein the wax has a melting point of 65 to 160 ° C. Dry magnetic toner according to any one of claims 1 to 9 liberated magnetic iron oxide particles, characterized in that the presence 100-300 per 10,000 magnetic toner particles. The magnetic toner is
a) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the formula 0 <cut rate Z ≦ 5.3 × X,
And, dry according to any one of claims 1 to 10, characterized in that the relationship of the weight average diameter X of the number-based cumulative value Y and the magnetic toner circularity of 0.950 or more of the particles satisfies the following equation Magnetic toner.
exp4.85 × X ^−0.187 ≧ Y ≧ exp5.51 × X ^−0.645 The magnetic toner is
b) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the expression 95 ≧ cut rate Z> 5.3 × X,
And, dry according to any one of claims 1 to 11, characterized in that the relationship between the weight average diameter X of the number-based cumulative value Y and the magnetic toner circularity of 0.950 or more of the particles satisfies the following equation Magnetic toner.
exp 4.85 × X ^−0.187 ≧ Y ≧ exp 5.37 × X ^−0.545 Dry magnetic toner according to any one of claims 1 to 12 weight average particle diameter of the magnetic toner is characterized in that it is a 5 to 10 [mu] m. Dry magnetic toner according to any one of claims 1 to 13 Magnetic iron oxide particles is characterized by number average particle diameter of 0.1 to 0.4 [mu] m. Forming an electrostatic charge image on the electrostatic charge image carrier, developing the electrostatic charge image with a dry magnetic toner held in the developing means to form a magnetic toner image;
In an image forming method in which the formed magnetic toner image is transferred to a transfer material with or without an intermediate transfer member, and the magnetic toner image on the transfer material is fixed to the transfer material by heating and pressing fixing means. ,
The magnetic toner is a dry magnetic toner having magnetic toner particles having at least a binder resin, magnetic iron oxide particles and wax, an inorganic fine powder and a hydrophobic inorganic fine powder,
The magnetic toner particles are obtained by melt-kneading a mixture containing at least a binder resin, magnetic iron oxide particles and wax, cooling the kneaded product, coarsely pulverizing the cooled product, and obtaining the coarsely pulverized product with a mechanical pulverizer. Obtained by pulverizing with
The inorganic fine powder and the hydrophobic inorganic fine powder are used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the magnetic toner.
The inorganic fine powder is strontium titanate, the hydrophobic inorganic fine powder is a hydrophobic silica fine powder,
100 to 350 free magnetic iron oxide particles are present per 10,000 magnetic toner particles,
The weight average particle diameter of the magnetic toner is 5 μm to 12 μm, and the circularity of the particles constituting the magnetic toner is a circularity measured by the following measurement method,
Measuring method: [Method for measuring the circularity of particles constituting the magnetic toner: 0.1 to 0.5 ml of a surfactant as a dispersing agent is added to 100 to 150 ml of water from which impurities in the container have been previously removed, and then the magnetic toner is added. 0.1 to 0.5 g is added, and the suspension in which the magnetic toner is dispersed is irradiated with ultrasonic waves (50 kHz, 120 W) for 1 to 3 minutes, and the dispersion concentration is set to 1.2 to 2 million pieces / μl. Using a flow type particle image measuring apparatus, the circularity distribution of particles having a circle-equivalent diameter of 0.60 μm or more and less than 159.21 μm is measured. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the following circularity calculation formula. ]
In the particles of 3 μm or more constituting the magnetic toner, 90% by number or more of particles having a circularity a of 0.900 or more obtained from the following formula (1) based on the number,
Circularity a = L ₀ / L (1)
[In the formula, L ₀ represents the circumference of a circle having the same projected area as the particle image, and L represents the circumference of the particle image. ]
A) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (2):
Cut rate Z ≦ 5.3 × X (2)
[However, the cut rate Z is expressed by the equation (3) when the particle concentration A (number / μl) of all measured particles and the measured particle concentration B (number / μl) of the equivalent circle diameter of 3 μm or more.
Z = (1-B / A) × 100 (3)]
In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (4);
Number-based cumulative value Y ≧ exp5.51 × X ^−0.645 of particles having a circularity of 0.950 or more (4)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
Or
b) The relationship between the cut rate Z and the weight average diameter X of the magnetic toner satisfies the following formula (5):
Cut rate Z> 5.3 × X (5)
In addition, the relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average diameter X of the magnetic toner satisfies the following formula (6);
Number-based cumulative value Y ≧ exp5.37 × X ^−0.545 of particles having a circularity of 0.950 or more (6)
[However, weight average particle diameter X of the magnetic toner: 5.0 to 12.0 μm]
An image forming method. The electrostatic image carrier is charged by contact charging means to which a bias is applied, and a digital latent image is formed by exposing the charged electrostatic image carrier, and the digital latent image is held in the developing means. A magnetic toner image is formed by developing with dry magnetic toner, and the magnetic toner image is transferred via an intermediate transfer member or by a contact transfer means in which a bias is applied to a transfer material. The image forming method according to claim 15 . 17. The developing device according to claim 15 or 16 , wherein the developing means has a developing sleeve containing the magnetic field generating means, and has an elastic blade for forming a magnetic toner layer on the developing sleeve. Image forming method. The image forming method according to any one of claims 15 to 17 , wherein the magnetic toner is the dry magnetic toner according to any one of claims 2 to 14 .

Images