JP3943982B2 - Dry toner, toner manufacturing method, image forming method, and process cartridge - Google Patents

Description

（２）
〔式中、各粒子における円形度がａ_ｉであり、測定粒子数がｍである。〕
【００５１】
本発明に用いている円形度はトナー粒子の凹凸度合いの指標であり、トナーが完全な球形の場合１．０００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。
【００５２】
なお、本発明で用いている測定装置である「ＦＰＩＡ−２１００」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０．０１０刻みで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。
【００５３】
さらに本発明で用いている測定装置である「ＦＰＩＡ−２１００」は、従来、トナーの形状を算出するために用いられていた「ＦＰＩＡ−１０００」と比較して、シースフロー（ＣＣＤカメラとストロボの間を試料溶液が流れる際のセルの厚み）の薄層化（７μｍ→４μｍ）及び処理粒子画像の倍率の向上、さらに取り込んだ画像の処理解像度を向上（２５６×２５６→５１２×５１２）によりトナーの形状測定の精度が上がっており、それにより微粒子のより確実な解析を達成している装置である。従って、本発明のように、より正確に形状を測定する必要がある場合には、より正確に形状に関する情報が得られるＦＰＩＡ２１００の方が有用である。ＦＰＩＡ−１０００は、粒子の粒径が小さくなるほど、粒子の輪郭を正確に捉えることができなくなり、円形度としてより高い値、即ちより丸く測定される傾向があった。
【００５４】
円形度の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、３．００μｍ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。
【００５５】
測定の概略は、以下の通りである。
【００５６】
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。
【００５７】
従来、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、特に３μｍ以上のトナーの形状とトナー表面に露出した磁性酸化鉄量が転写性、現像性に大きく影響をおり、これらを制御することで、粉砕法によるトナーで現像兼クリーニング方法及びクリーナーレス画像形成方法が良好に実現できることを見出した。現像兼クリーニング方法及びクリーナーレス画像形成方法では、感光体上の転写残トナー粒子の帯電極性及び帯電量を制御し、現像工程で安定して転写残トナー粒子を回収し、回収トナーが現像特性を悪化させないようにすることがポイントであり、本願発明に係るトナーを用いた場合には、これらが良好に達成される。
【００５８】
本発明のトナーは、該トナーの３μｍ以上の粒子において、下記式（１）
円形度ａ＝Ｌ₀／Ｌ （１）
〔式中、Ｌ₀は粒子像と同じ投影面積を持つ円の周囲長を示し、Ｌは５１２×５１２の画像処理解像度（０．３μｍ×０．３μｍの画素）で画像処理した時の粒子像の周囲長を示す。〕
より求められる円形度ａが０．９００以上の粒子を個数基準の累積値で８５％以上有し、且つ、円形度０．９５０以上の粒子の個数基準累積値Ｙとトナーの重量平均粒径Ｘの関係が下記式（２）
円形度０．９５０以上の粒子の個数基準累積値Ｙ≧ｅｘｐ５．３１×Ｘ^-0.715（２）
［但し、トナーの重量平均粒径Ｘは、４．０〜１２．０μｍである。］
を満足するものである。
【００５９】
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あり、帯電の均一性に優れ、帯電の耐久安定性のあるトナーを得ることができるため、転写残トナーが感光体から回収された後も回収トナーにおいても帯電性が安定しており、再び現像させる場合における帯電のコントロールが可能となる。さらに、このような円形度を有する場合、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、転写効率が高くなる。さらに、一般的な粉砕トナーと比較して、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できる。
【００６０】
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８５％未満となる場合には、トナー粒子と現像剤担持体、感光体等との接触面積が大きくなるため、トナーのチャージのリークが現像剤担持体、感光体等と接触した部分を通して起こりやすくなり、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。
【００６１】
また、該トナーの３μｍ以上の粒子において、円形度０．９５０以上の粒子の個数基準累積値Ｙとトナーの重量平均粒径Ｘとの関係が、下記式
円形度０．９５０以上の粒子の個数基準累積値Ｙ＜ｅｘｐ５．３１×Ｘ^-0.715［但し、トナーの重量平均粒径Ｘは、４．０〜１２．０μｍである。］
のようになる場合、トナーの流動性に劣り、又、十分な転写効率が得られないだけでなく、さらには所望の定着性能も得にくいものである。
【００６２】
また、本発明のトナーは、重量平均粒径が４〜１２μｍであることを特徴とする。更に好ましくは、重量平均粒径が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。
【００６３】
重量平均粒径が１２μｍを上回るトナーは、形状は角張ったものとなり、所定の円形度にすることは難しく、更に所定の円形度分布にすることは難しくなる。
【００６４】
重量平均粒径が４μｍを下回るトナーは、形状が球形に近くなりすぎたり、熱による球形化が進行し表面の磁性酸化鉄が被覆されてしまったりと、円形度分布と表面近傍の磁性酸化鉄量との両者をコントロールすることは難しく、また微粉、超微粉の発生を押さえ切れなくなる。
【００６５】
粒径４．０μｍ以下の粒子が４０個数％を超えるトナーは、形状が球形に近くなりすぎたり、熱による球形化が進行し表面の磁性酸化鉄が被覆されてしまったりしやすく、円形度分布と表面近傍の磁性酸化鉄量との両者をコントロールすることは難しくなる。
【００６６】
粒径１０．１μｍ以上の粒子が２５体積％を超えるトナーは、形状は角張ったものとなりやすいため、所定の円形度にすることは難しく、更に円形度分布をコントロールすることは難しくなる。
【００６７】
このような粒子のバラツキを表す一つの目安として、下記式から求められる円形度標準偏差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０．０６５であれば問題は無い。
【００６８】
【外２】

【００６９】
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。
【００７０】
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性が低下し、粉砕，表面処理工程によるトナー表面への磁性酸化鉄の露出度合いを所定の範囲にコントロールすることが困難になる。しかも、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に劣るようになりやすい。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。
【００７１】
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。
【００７２】
＜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）０．１ｍｏｌ／ｌ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。
酸価（ｍｇＫＯＨ／ｇ）＝（（Ｓ−Ｂ）×ｆ×５．６１）／Ｗ
【００７３】
本発明のトナーに使用される結着樹脂としては、下記の結着樹脂の使用が可能である。
【００７４】
例えば、ポリスチレン，ポリ−ｐ−クロルスチレン，ポリビニルトルエンの如きスチレンおよびその置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体，スチレン−ビニルトルエン共重合体，スチレン−ビニルナフタリン共重合体，スチレン−アクリル酸エステル共重合体，スチレン−メタクリル酸エステル共重合体，スチレン−α−クロルメタクリル酸メチル共重合体，スチレン−アクリロニトリル共重合体，スチレン−ビニルメチルエーテル共重合体，スチレン−ビニルエチルエーテル共重合体，スチレン−ビニルメチルケトン共重合体，スチレン−ブタジエン共重合体，スチレン−イソプレン共重合体，スチレン−アクリロニトリル−インデン共重合体の如きスチレン系共重合体；ポリ塩化ビニル，フェノール樹脂，天然変性フェノール樹脂，天然樹脂変性マレイン酸樹脂，アクリル樹脂，メタクリル樹脂，ポリ酢酸ビニール，シリコーン樹脂，ポリエステル樹脂，ポリウレタン，ポリアミド樹脂，フラン樹脂，エポキシ樹脂，キシレン樹脂，ポリビニルブチラール，テルペン樹脂，クマロンインデン樹脂，石油系樹脂が使用できる。好ましい結着物質としては、スチレン系共重合体もしくはポリエステル樹脂がある。
【００７５】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸，アクリル酸メチル，アクリル酸エチル，アクリル酸ブチル，アクリル酸ドデシル，アクリル酸オクチル，アクリル酸−２−エチルヘキシル，アクリル酸フェニル，メタクリル酸，メタクリル酸メチル，メタクリル酸エチル，メタクリル酸ブチル，メタクリル酸オクチル，アクリロニトリル，メタクリニトリル，アクリルアミドの如き二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸，マレイン酸ブチル，マレイン酸メチル，マレイン酸ジメチルの如き二重結合を有するジカルボン酸およびその置換体；例えば塩化ビニル，酢酸ビニル，安息香酸ビニルの如きビニルエステル類；例えばエチレン，プロピレン，ブチレンの如きエチレン系オレフィン類；例えばビニルメチルケトン，ビニルヘキシルケトンの如きビニルケトン類；例えば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などのようなビニルエーテル類；の如きビニル単量体が単独もしくは２つ以上用いられる。
【００７６】
スチレン系重合体またはスチレン系共重合体は架橋されていても良く、またそれらの混合樹脂でも良い。
【００７７】
本発明に係る結着樹脂は、保存性の観点から、ガラス転移温度（Ｔｇ）が４５〜７５℃、好ましくは５０〜７０℃であり、Ｔｇが４５℃より低いと高温雰囲気下でトナーが劣化し易く、定着時にオフセットが発生し易くなる。また、Ｔｇが７５℃を超えると定着性が低下する傾向にある。
【００７８】
本発明に用いられる磁性体としては、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が用いられ、その磁性酸化鉄表面あるいは内部に非鉄元素を含有するものが好ましい。
【００７９】
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，ケイ素，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を含有する磁性酸化鉄であることが好ましい。特にリチウム，ベリリウム，ボロン，マグネシウム，アルミニウム，ケイ素，リン，ゲルマニウム，ジルコニウム，錫が好ましい元素である。これらの元素は酸化鉄結晶格子の中に取り込まれても良いし、酸化物として酸化鉄中に取り込まれても良いし、表面に酸化物あるいは水酸化物として存在しても良い。また、酸化物として含有されているのが好ましい形態である。
【００８０】
また、トナー中に含有される量としては樹脂成分１００質量部に対して２０〜２００質量部、特に好ましくは樹脂成分１００質量部に対して４０〜１５０質量部がさらに良い。
【００８１】
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。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。
【００８２】
本発明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。
【００８３】
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。
【００８４】
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。
【００８５】
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。
【００８６】
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複数のワックス類を併用しても構わない。
【００８７】
本発明においてワックスの融点は、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。
【００８８】
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、高精度の内熱式入力補償型の示差走査熱量計で測定することが好ましい。例えば、パーキンエルマー社製のＤＳＣ−７が利用できる。
【００８９】
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。
【００９０】
本発明の乾式トナーには、添加し得る着色材料として、従来公知のカーボンブラック、銅フタロシアニンの如き顔料または染料などが使用できる。
【００９１】
本発明においては、荷電制御剤を添加して使用することが好ましい。負荷電制御剤の具体例としては、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号公報など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などの染顔料、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号公報など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，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が得られる、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。
【００９２】
【外３】

【００９３】
［式中、Ｍは配位中心金属を表し、Ｃｒ，Ｃｏ，Ｎｉ，Ｍｎ，Ｆｅ，Ｔｉ又はＡｌを示す。Ａｒは、フェニル基，ナフチル基の如きアリール基であり、置換基を有してもよい。この場合の置換基としては、ニトロ基，ハロゲン基，カルボキシル基，アニリド基及び炭素数１〜１８のアルキル基，炭素数１〜１８のアルコキシ基がある。Ｘ，Ｘ’，Ｙ，Ｙ’は−Ｏ−，−ＣＯ−，−ＮＨ−，−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。Ａ⁺は水素イオン，ナトリウムイオン，カリウムイオン，アンモニウムイオン又は脂肪族アンモニウムイオンを示す。］
【００９４】
【外４】

【００９５】
［式中、Ｍは配位中心金属を表し、Ｃｒ，Ｃｏ，Ｎｉ，Ｍｎ，Ｆｅ，Ｔｉ，Ｚｒ，Ｚｎ，Ｓｉ，Ｂ又はＡｌを示す。（Ｂ）は
【外５】

【００９６】
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。
【００９７】
【外６】

【００９８】
［式中、Ｘ₂及びＸ₃は水素原子，低級アルキル基，低級アルコキシ基，ニトロ基又はハロゲン原子を示し、ｋ及びｋ’は１〜３の整数を示し、Ｙ₁およびＹ₃は水素原子，Ｃ₁〜Ｃ₁₈のアルキル，Ｃ₂〜Ｃ₁₈のアルケニル，スルホンアミド，メシル，スルホン酸，カルボキシエステル，ヒドロキシ，Ｃ₁〜Ｃ₁₈のアルコキシ，アセチルアミノ，ベンゾイル，アミノ基又はハロゲン原子を示し、ｌ及びｌ’は１〜３の整数を示し、Ｙ₂およびＹ₄は水素原子またはニトロ基を示し、上記のＸ₂とＸ₃，ｋとｋ’，Ｙ₁とＹ₃，ｌとｌ’，Ｙ₂とＹ₄は同一であっても異なっていても良く、Ａ^''+はアンモニウムイオン，ナトリウムイオン，カリウムイオン，水素イオン又はそれらの混合イオンを示し、好ましくはアンモニウムイオンを７５〜９８モル％有する。］
【００９９】
【外７】

【０１００】
［式中Ｒ₁〜Ｒ₂₀は水素，ハロゲン或いはアルキル基を示し、Ａ⁺はアンモニウムイオン，ナトリウムイオン，カリウムイオン，水素イオン又はそれらの混合イオンを示す。］
【０１０１】
次に上記式（ＩＩＩ）で示されるアゾ系鉄錯体の具体例を示す。
【外８】

【０１０２】
【外９】

【０１０３】
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。
【０１０４】
【外１０】

【０１０５】
【化１】

【０１０６】
【外１１】

【０１０７】
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。
【０１０８】
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。
【０１０９】
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。
【０１１０】
ニグロシン及び脂肪酸金属塩等による変性物、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等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、フェロシアン化物が挙げられる。）、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種類以上組み合わせて用いることができる。
【０１１１】
また、本発明の磁性トナーには、無機微粉体または疎水性無機微粉体が混合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。
【０１１２】
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いわゆる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等から製造されるいわゆる湿式シリカの両方が使用可能であるが、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。
【０１１３】
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など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化合物で処理した後、あるいはシラン化合物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。
【０１１４】
疎水化処理に使用されるシラン化合物としては、例えば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。
【０１１５】
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、例えばジメチルシリコーンオイル、メチルハイドロジェンシリコーンオイル、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。
【０１１６】
シリコーンオイル処理の方法は例えばシラン化合物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等の混合機を用いて直接混合しても良いし、ベ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、ベ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。
【０１１７】
さらに、本発明においては、トナー粒子１００個当たり、粒径０．６〜３．０μｍの導電性微粉末を５〜３００個有することがクリーナーレス画像形成方法に用いる上で好ましい。粒径０．６〜３．０μｍの導電性微粉末は、トナー粒子から遊離して挙動しやすく、帯電部材に均一に付着しかつ安定して保持されるために、トナー中に導電性微粉末をトナー粒子１００個当たり５〜３００個有することで、現像工程及び転写工程において帯電性を均一化できる。また、トナー中に０．６〜３μｍの粒径の導電性微粉末をトナー粒子１００個当たり５〜３００個有することで、現像兼クリーニング工程における転写残トナー粒子の回収性がより安定する。
【０１１８】
本発明における導電性微粉末としては、例えばカーボンブラック，グラファイトの如き炭素微粉末；銅，金，銀，アルミニウム，ニッケルの如き金属微粉末；酸化亜鉛，酸化チタン，酸化スズ、酸化アルミニウム，酸化インジウム，酸化ケイ素，酸化マグネシウム，酸化バリウム，酸化モリブデン，酸化鉄，酸化タングステンの如き金属酸化物；硫化モリブデン，硫化カドミウム，チタン酸カリの如き金属化合物；あるいはこれらの複合酸化物のうち一次粒子の個数平均粒径が５０〜５００ｎｍであり、一次粒子の凝集体を有する導電性微粉末が使用でき、トナーとしての粒度及び粒度分布を調整するために粒度分布の調整された導電性微粉末を用いることも好ましい。
【０１１９】
また、本発明中の磁性トナーには、必要に応じてそれ以外の外部添加剤を添加してもよい。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、滑剤、研磨剤として働く樹脂微粒子や無機微粒子である。
【０１２０】
例えばテフロン（Ｒ），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。或いは、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。或いは、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、或いはカーボンブラック，酸化亜鉛，酸化アンチモン，酸化スズの如き導電性付与剤、また逆極性に帯電する微粒子を現像性向上剤として少量用いることもできる。
【０１２１】
磁性トナーと混合される外部添加剤は、磁性トナー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。
【０１２２】
以下、本発明の好ましいトナーの製造方法の実施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を特徴としている。
【０１２３】
本発明のトナーの製造方法においては、特定の円形度を有するトナーを製造することで、トナー表面の磁性酸化鉄の露出度合いをある程度、制御している。本発明においては、結着樹脂、磁性酸化鉄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、冷却物を粗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、先ず、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である回転子と、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、該間隔を保持しつつ粉砕を行う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原料となる分級品が得られる。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る。その後、得られた中粉体を連続的に機械的衝撃力を加える表面処理装置内を通過させることによって所望のトナー粉体が得られ、トナー製品としてそのまま使用されるか、又は、疎水性シリカの如き外部添加剤と混合された後、トナーとして使用される。
【０１２４】
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ため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。
【０１２５】
図２に本発明のトナーの製造方法を適用した装置システムの一例を示し、これに基づいて本発明を更に具体的に説明する。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、着色剤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。
【０１２６】
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、先ず、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。
【０１２７】
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生産性及び生産効率という点から好ましい。
【０１２８】
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、多分割気流式分級機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。
【０１２９】
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により多分割気流式分級機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。多分割気流式分級機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、多分割気流式分級機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を介して、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ため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ための吸引減圧手段としての働きをすることも可能である。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。尚、分級装置内に気体を導入する入気管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。
【０１３０】
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。
【０１３１】
この装置システムにおいて、粉体原料の粒度は、目開き１０００μｍの篩を通過する粒子（１８メッシュパス（ＡＳＴＭＥ−１１−６１））が９５質量％以上であり、目開き１５０μｍの篩を通過できない粒子（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。
【０１３２】
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ためには、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４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。
【０１３３】
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、微粉砕処理前の第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。
【０１３４】
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）製ターボミル等を挙げることができ、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。
【０１３５】
本発明においては、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、トナーを製造することが、トナーの形状とトナー表面の磁性酸化鉄の露出量を容易に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。
【０１３６】
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、トナーからの磁性酸化鉄粒子の露出が多くなる。また、衝突式気流粉砕で製造されたトナーを機械式衝撃（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、本発明における効果を発揮させるだけの円形度を達成するためには熱により粒子の形状を改質させ形状を球形に近づけていく必要があり、トナー表面への磁性酸化鉄の露出量をコントロールすることは困難である。
【０１３７】
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、本発明において使用される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ための原料投入口３１１、処理後の粉体を排出するための原料排出口３０２とから構成されている。
【０１３８】
以上のように構成してなる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、及び吸引ブロワー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ため、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。尚、２４０は粉体原料ホッパー、３１５は第１定量供給機である。
【０１３９】
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等の不凍液）を通水することにより、粉砕機内の雰囲気温度を２０〜−４０℃、より好ましくは１０〜−３０℃、更に好ましくは０〜−２５℃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２１２の室温を２０〜−４０℃、より好ましくは１０〜−３０℃、更に好ましくは０〜−２５℃とすることにより、熱によるトナーの表面変質、特にトナー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。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の表面変質、特にトナー表面に存在する磁性酸化鉄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。
【０１４０】
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。
【０１４１】
なお、冷却水（好ましくはエチレングリコール等の不凍液）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。
【０１４２】
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３２０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、熱によるトナーの表面変質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、十分に粒子の粉砕が行われずに排出されてしまう、所謂ショートパスを起こしている可能性があり、トナー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の遊離や熱によるトナー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。
【０１４３】
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、熱によるトナーの表面変質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、熱によるトナーの表面変質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。
【０１４４】
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、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、トナーの粉砕不足や過粉砕、さらに過粉砕によ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。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熱によるトナー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。
【０１４５】
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、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によるトナーの表面変質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が遊離する。さらに、過粉砕されることにより、熱によるトナー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。
【０１４６】
また、本発明で用いられる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、良好な現像性、転写性ならびに帯電性を有するトナーを得ることができる。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熱によるトナーの表面変質、特にトナー表面に存在する磁性酸化鉄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。
【０１４７】
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た。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として測定した。
【０１４８】
なお、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。
【０１４９】
【外１２】

【０１５０】
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。なお、本発明の回転子及び／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。
【０１５１】
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。
【０１５２】
即ち、本発明者らが検討した結果、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、容易にトナー粒子表面に露出する磁性酸化鉄量をコントロールでき、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トナーを粉砕することが可能となることがわかった。
【０１５３】
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，メッキ，溶射，自溶性合金による肉もり等の処理が最も好ましい。
【０１５４】
前記窒化とは、加工材料の耐摩耗性や耐疲労性を向上させる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。
【０１５５】
本発明の粉砕方法は、粗粉砕工程後の第１分級工程を必要としないため、微粒子化されることにより生じる粒子間の静電凝集によって、本来は第２分級手段に送られるべき磁性トナーが再度第１分級手段に循環され、結果、過粉砕されてしまい微粉及び超微粉となるのを防ぐことができ、そのため分級収率が良好となる。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ため、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。
【０１５６】
次に、本発明の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。
【０１５７】
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。
【０１５８】
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。
【０１５９】
原料粉体を導入するための原料供給口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２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。
【０１６０】
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。
【０１６１】
また、分級室３２の気流下流側にはそれぞれの分画域に対応させて、分級室内に開口する排出口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。
【０１６２】
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。
【０１６３】
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。
【０１６４】
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。
【０１６５】
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。
【０１６６】
また、本発明の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、重量平均粒径が１０μｍ以下（特に、８μｍ以下）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。
【０１６７】
本発明の乾式トナーは、トナー粒子表面が、連続的に機械的衝撃力を加える表面処理装置内を通過させる表面処理工程によって表面処理されていることを特徴とする。そこで、本発明のトナー製造方法を構成しているトナーの表面処理方法として好ましく用いられている方法について、図１０〜１３を用いて説明する。
【０１６８】
図１０は表面改質装置システムの構造を示す模式的概略構成図であり、図１１は、図１０のシステムにおける表面改質装置Ｉの処理部４０１の構造を示す模式的部分的断面図である。また、図１２及び１３は、表面改質装置に取り付けられているローターの平面図及び断面図である。
【０１６９】
この表面改質装置は、高速回転する羽根によりトナー粒子をケーシングの内側に遠心力により押しつけ、少なくとも圧縮力及び摩擦力による熱機械的衝撃力を繰り返し与えることによりトナー粒子の表面処理を行うものである。図１１に示すように、処理部４０１には鉛直方向に４枚の回転ローター４０２ａ、４０２ｂ、４０２ｃ及び４０２ｄが設置されている。これら回転ローター４０２ａ〜４０２ｄは、最外縁部の周速が例えば３０〜６０ｍ／ｓとなるように、電動モータ４３４により回転駆動軸４０３を回転させることによって回転される。さらに、吸引ブロアー４２４（図１０参照）を稼働させて、各回転ローター４０２ａ〜４０２ｄと一体に設けられたブレード４０９ａ〜４０９ｄの回転によって発生する気流量と同等、またはそれよりも多い風量を吸引する。フィーダー４１５からトナー粒子が空気とともにホッパー４３２に吸引導入され、導入されたトナー粒子は、粉体供給管４３１及び粉体供給口４３０を通って第１の円筒状処理室８９ａの中央部に導入される。このトナー粒子は、第１の円筒状処理室４２９ａでブレード４０９ａと側壁４０７により表面処理を受け、次いで、表面処理を受けたトナー粒子はガイド板４０８ａの中央部に設けられた第１の粉体排出口４１０ａを通って、第２の円筒状処理室４２９ｂの中央部に導入され、さらにブレード４０９ｂと側壁４０７により球形化処理を受ける。
【０１７０】
第２の円筒状処理室４２９ｂで表面処理されたトナー粒子は、ガイド板４０８ｂの中央部に設けられた第２の粉体排出口４１０ｂを通って第３の円筒状処理室４２９ｃの中央部に導入され、さらにブレード４０９ｃと側壁４０７により表面処理を受け、さらに、ガイド板４０８ｃの中央部に設けられた第３の粉体排出口４１０ｃを通って第４の円筒状処理室４２９ｄの中央部にトナー粒子は導入され、ブレード４０９ｄと側壁４０７により表面処理を受ける。トナー粒子を搬送している空気は、第１〜第４の円筒状処理室４２９ａ〜４２９ｄを経由し、搬出管４１７、サイクロン４２０、バグフィルター４２２、及び吸引ブロアー４２４を通って装置システムの系外に排出される。
【０１７１】
各円筒状処理室４２９ａ〜４２９ｄ内に導入されたトナー粒子は、各ブレード４０９ａ〜４０９ｄによって瞬聞的に機械的打撃作用を受け、さらに、側壁４０７に衝突して機械的衝撃力を受ける。回転ローター４０２ａ〜４０２ｄにそれぞれ設置されている所定の大きさのブレード４０９ａ〜４０９ｄの回転により、回転ローター面の上方空間に、中央部から外周へ、外周から中央部へ循環する対流が発生する。トナー粒子は円筒状処理室４２９ａ〜４２９ｄ内に滞留し、表面処理を受ける。この機械的衝撃力により発生する熱により、トナー粒子表面の処理がなされる。
【０１７２】
具体的な方法としては、各々のローターを３０〜６０ｍ／ｓで回転させ、図１０に示すように、表面改質装置Ｉの出口側にサイクロン４２０及びブロアー４２４を取り付け、ブロアー風量２〜４ｍ^３／分に吸引した状態で、オートフィーダー４１５にて毎時１０〜３０ｋｇの速度で処理装置上部の投入口４３２よりトナーを供給する。上記表面処理工程において、結着樹脂のガラス転移温度Ｔｇよりも５℃以上低い温度［即ち、気流温度Ｔ≦（結着樹脂のＴｇ−５℃）］の気流中で、トナー粒子を滞留させることなく表面処理装置内を通過するようにして、トナー粒子に連続的に機械的衝撃力を加えることによって得られる表面処理トナーとすることが好ましい。また、上記表面処理工程において、ワックスのＤＳＣ吸熱メインピーク温度よりも２０℃以上低い温度［即ち、気流温度Ｔ≦（ワックスのＤＳＣ吸熱メインピーク温度−２０℃）］の気流中で、トナー粒子を滞留させることなく表面処理装置内を通過するようにして、トナー粒子に連続的に機械的衝撃力を加えることによって得られる表面処理トナーとすることが好ましい。これに対して、（結着樹脂のＴｇ−５℃）以上、又は（ワックスのピーク温度−２０℃）以上の温度でトナー粒子の表面処理を行った場合には、表面処理時に発生する摩擦熱が蓄積し、トナー中に分散されているワックスがトナー表面に滲み出して再凝集する等、熱によるトナー表面の変質を起こすことがあるので好ましくない。
【０１７３】
このように先に述べた機械式粉砕機と連続的に機械的衝撃力を加える表面処理装置内を通過させてトナー粒子表面を表面処理することとを組み合わせることにより、本発明においては、機械的衝撃力や摩擦によって生じるトナー粒子の発熱が有効に抑制された状態で、熱を蓄積させることなく、低温、短時間で十分なトナー粒子の表面処理を行うことが可能となり円形度とトナー表面の磁性酸化鉄の露出量を容易にコントロールすることが可能となる。
【０１７４】
本発明のトナーの製造方法は、静電荷像を現像するために使用されるトナー粒子の生成に好ましく使用することができる。本発明のトナーを作製するには、結着樹脂及び磁性酸化鉄を少なくとも含有する混合物が材料として用いられるが、その他、必要に応じて荷電制御剤、ワックス及びその他の添加剤等が用いられる。これらの材料をヘンシェルミキサー又はボールミルの如き混合機により十分混合してから、ロール、ニーダー及びエクストルーダーの如き熱混練機を用いて溶融、捏和及び混練して樹脂類を互いに相溶、混合せしめた中に、必要に応じ顔料又は染料を分散又は溶解せしめ、冷却固化後、粉砕及び分級を行ってトナーを得ることができる。例えば混合機としては、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、ニダールーダー（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（日新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。
【０１７５】
本発明においては、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。
【０１７６】
本発明の画像形成装置の構成を図１４を参照して説明する。
【０１７７】
この画像形成装置は、転写式電子写真プロセスを利用した現像兼クリーニングプロセス（クリーナーレスシステム）の記録装置である。クリーニングブレードの如きクリーニング部材を有するクリーニングユニットを除去したプロセスカートリッジを有し、現像剤としては磁性一成分現像剤（磁性トナー）を使用し、現像剤担持体（トナー担持体）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。
【０１７８】
５０１は静電荷像保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。５０２は接触帯電部材としての帯電ローラーである。帯電ローラー５０２は感光体５０１に対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５０１と帯電ローラー５０２のニップ部である帯電ニップ部である。本実施例では、帯電ローラー５０２は感光体５０１との接触面である帯電ニップ部ｎにおいてカウンター方向（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、帯電ローラー５０２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が担持される。
【０１７９】
また帯電ローラー５０２の芯金５０２ａ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する。本実施例では感光体５０１の表面は帯電ローラー５０２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。
【０１８０】
５０３はレーザーダイオード、ポリゴンミラー等を含むレーザービームスキャナー（露光器）である。このレーザービームスキャナー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ー光（波長７４０ｎｍ）を出力し、該レーザー光Ｌで感光体５０１の一様帯電面を走査露光する。この走査露光により感光体５０１に目的の画像情報に対応した静電潜像が形成される。
【０１８１】
５０４は現像装置である。感光体５０１の表面の静電潜像がこの現像装置によりトナー画像として現像される。本実施例の現像装置５０４は、現像剤として負帯電性磁性一成分絶縁現像剤（磁性トナー）を用いた、非接触型の反転現像装置である。現像剤５０４ｄにはトナー粒子（ｔ）及び導電性微粉末（ｍ）が含有されている。
【０１８２】
５０４ａは現像剤担持搬送部材としての、マグネットロール５０４ｂ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５０４ａは、感光体５０１に対して３２０μｍの離間距離をあけて対向配設し、感光体５０１との対向部である現像部（現像領域部）ａにて感光体５０１の回転方向と順方向に感光体５０１に対して１２０％の周速で回転される。
【０１８３】
この現像スリーブ５０４ａ上に、現像剤５０４ｄが弾性ブレード５０４ｃによって薄層にコートされる。現像剤５０４ｄは、弾性ブレード５０４ｃによって現像スリーブ５０４ａ上での層厚が規制されるとともに電荷が付与される。
【０１８４】
現像スリーブ５０４ａにコートされた現像剤５０４ｄは、現像スリーブ５０４ａが回転することによって、感光体５０１と該現像スリーブ５０４ａの対向部である現像部ａに搬送される。
【０１８５】
また、現像スリーブ５０４ａ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５０４ａと感光体５０１の間で一成分ジャンピング現像を行わせる。
【０１８６】
５０５は接触転写手段としての中抵抗の転写ローラーであり、感光体５０１に０．１６×１０^-2〜２４．５×１０^-2ＭＰａの当接圧をかけ転写ニップ部ｂを形成している。この転写ニップ部ｂに図示せぬ給紙部から所定のタイミングで記録媒体としての転写材Ｐが給紙され、かつ転写ローラー５０５に転写バイアス印加電源Ｓ３から所定の転写バイアス電圧が印加されることで、感光体５０１側のトナー像が転写ニップ部ｂに給紙された転写材Ｐの面に順次に転写されていく。
【０１８７】
本実施例では転写ローラー５０５は抵抗が５×１０⁸Ωｃｍのものを用い、＋２０００Ｖの直流電圧を印加して転写を行った。即ち、転写ニップ部ｂに導入された転写材Ｐはこの転写ニップ部ｂを挟持搬送されて、その表面側に感光体５０１の表面に形成担持されているトナー画像が順次に静電気力と押圧力にて転写されていく。
【０１８８】
５０６は熱定着方式等の定着装置である。転写ニップ部ｂに給紙され、トナー像が転写された転写材Ｐは、感光体５０１の表面から分離されてこの定着装置５０６に導入され、トナー像の定着を受けて画像形成物（プリント、コピー）として装置外へ排出される。
【０１８９】
本例の画像形成装置はクリーニングユニットを除去しており、転写材Ｐに対するトナー像転写後の感光体５０１の表面に残留の転写残りの現像剤（転写残トナー）ｔｒはクリーニング手段で除去されることなく、感光体５０１の回転に伴い帯電部ｎを経由して現像部ａに至り、現像装置５０４においてクリーニング（回収）される。
【０１９０】
本例のプリンターは、感光体５０１、帯電ローラー５０２、現像装置５０４の３つのプロセス機器を一括してプリンター本体に対して着脱自在のプロセスカートリッジとして構成してある。プロセスカートリッジ化するプロセス機器の組み合わせ等は上記に限られるものではなく、クリーニング工程を有していても良く任意である。
【０１９１】
現像装置５０４の現像剤５０４ｄに混入させた導電性微粉末ｍは、感光体５０１側の静電潜像の現像装置５０４による現像時に、トナー粒子ｔとともに適当量が感光体５０１側に移行する。
【０１９２】
感光体５０１上のトナー画像、すなわちトナー粒子ｔは、転写部ｂにおいて転写バイアスの影響で記録媒体である転写材Ｐ側に引かれて積極的に転移する。しかし、感光体５０１上の導電性微粉末ｍは導電性であるため転写材Ｐ側には積極的には転移せず、感光体５０１上に実質的に付着保持されて残留する。
【０１９３】
本例においては、画像形成装置はクリーニング工程を有さないため、転写後の感光体５０１の表面に残存した転写残トナー粒子ｔおよび導電性微粉末ｍは、感光体５０１の回転に伴って感光体５０１と接触帯電部材である帯電ローラー５０２のニップ部である帯電部ｎに持ち運ばれて、帯電ローラー５０２に付着或いは混入する。従って、感光体５０１と帯電ローラー５０２とのニップ部ｎにこの導電性微粉末ｍが存在した状態で感光体５０１の直接注入帯電が行なわれる。
【０１９４】
この導電性微粉末ｍの存在により、帯電ローラー５０２に転写残トナー粒子ｔが付着・混入した場合でも、帯電ローラー５０２の感光体５０１への緻密な接触性と接触抵抗を維持できるため、該帯電ローラー５０２による感光体５０１の直接注入帯電を行わせることができる。
【０１９５】
つまり、帯電ローラー５０２が導電性微粉末ｍを介して密に感光体５０１に接触し、導電性微粉末ｍが感光体５０１表面を摺擦する。これにより、帯電ローラー５０２による感光体５０１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、従来のローラー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、帯電ローラー５０２に印加した電圧とほぼ同等の電位を感光体５０１に与えることができる。
【０１９６】
また帯電ローラー５０２に付着或いは混入した転写残トナー粒子ｔは、帯電ローラー５０２から徐々に感光体５０１上に吐き出され、感光体５０１表面の移動に伴って現像部ａに至り、現像工程時、現像装置５０４においてクリーニング（回収）される。
【０１９７】
現像兼クリーニングは、転写後に感光体５０１上に残留したトナー粒子を、画像形成工程の次回以降の現像時（現像後、再度帯電工程、露光工程を介した後の潜像の現像時）において、現像装置のカブリ取りバイアス（現像装置に印加する直流電圧と感光体の表面電位間の電位差であるカブリ取り電位差Ｖｂａｃｋ）によって回収するものである。本実施例における画像形成装置のように、反転現像の場合、この現像兼クリーニングは、現像バイアスによる感光体の暗部電位から現像スリーブにトナー粒子を回収する電界と、現像スリーブから感光体の明部電位へトナー粒子を付着させる（現像する）電界の作用でなされる。また、画像形成装置が稼働されることで、現像装置５０４の現像剤に含有された導電性微粉末ｍが、現像部ａで感光体５０１表面に移行し、感光体５０１表面の移動に伴って転写部ｂを経て帯電部ｎに持ち運ばれることによって、帯電部ｎに新しい導電性微粉末ｍが逐次に供給され続けるため、帯電部ｎにおいて導電性微粉末ｍが脱落等で減少したり、帯電部ｎの導電性微粉末ｍが劣化したりしても、帯電性の低下が生じることが防止されて感光体５０１の良好な帯電性が安定して維持される。
【０１９８】
かくして、接触帯電方式、転写方式、トナーリサイクルプロセスの画像形成装置において、接触帯電部材として簡易な帯電ローラー５０２を用いて、像担持体としての感光体５０１に均一な帯電性を低印加電圧で与えることができる。しかも帯電ローラー５０２が転写残トナー粒子ｔにより汚染されるにも拘わらず、オゾンレスの直接注入帯電を長期に渡り安定に維持させることができ、均一な帯電性を与えることができる。よって、オゾン生成物による障害、帯電不良による障害等のない、簡易な構成、低コストな画像形成装置を得ることができる。
【０１９９】
また、図１４に示す画像形成装置に代えて、図１５に示す中間転写体を用いた画像形成装置を用いることも可能である。図１５は、静電荷像保持体上のトナー画像を中間転写体上に転写した後中間転写体上のトナー画像を記録材上に二次転写するタイプの画像形成装置であり、本発明の乾式トナーのように高転写性で帯電の安定したトナーには好ましい画像形成装置である。
【０２００】
静電荷像保持体６０１は、基材６０１ａ上に有機光半導体を有する感光層６０１ｂを有し、矢印方向に回転し、対向し接触回転する帯電ローラー６０２（導電性弾性層６０２ａ，芯金６０２ｂ）により感光体６０１上に約−６００Ｖの表面電位に帯電させる。露光６０３は、ポリゴンミラーにより感光体上にデジタル画像情報に応じてオン−オフさせることで露光部電位が−１００Ｖ，暗部電位が−６００Ｖの静電荷像が形成される。複数の現像器６０４−１、６０４−２、６０４−３、６０４−４を用い、マゼンタトナー，シアントナー，イエロートナーまたはブラックトナーを感光体６０１上に反転現像方法を用いトナー画像を得た。該トナー画像は、一色毎に中間転写体６０５（弾性層６０５ａ，支持体としての芯金６０５ｂ）上に転写され中間転写体６０５上に４色の色重ね顕色像が形成される。感光体６０１上の転写残トナーはクリーナー部材６０８により、残トナー容器６０９中に回収される。
【０２０１】
本発明に係わるトナーは、転写効率が高いため、簡単なバイアスローラー又はクリーナー部材のない系においても問題が発生しにくい。
【０２０２】
中間転写体６０５は、パイプ状の芯金６０５ｂ上にカーボンブラックの導電付与部材をニトリル−ブタジエンラバー（ＮＢＲ）中に十分分散させた弾性層６０５ａをコーティングした。該コート層の硬度はＪＩＳ Ｋ−６３０１に準拠し３０度で、且つ体積固有抵抗値は１０⁹Ω・ｃｍであった。感光体６０１から中間転写体６０５への転写に必要な転写電流は約５μＡであり、これは電源より＋２０００Ｖを芯金６０５ｂ上に付与することで得られた。中間転写体６０５から転写材６０６へトナー画像を転写後に中間転写体表面をクリーナー部材６１０でクリーニングしてもよい。転写工程後、転写材上のトナー画像は、定着器６１１で定着される。
【０２０３】
転写ローラー６０７は、２０ｍｍの芯金６０７ｂ上にカーボンの導電性付与部材をエチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）の発泡体中に十分分散させたものをコーティングすることにより生成した弾性層６０７ａの体積固有抵抗値が、１０^６Ω・ｃｍでＪＩＳ Ｋ−６３０１基準の硬度が３５度の値を示すものを用いた。転写ローラーには電圧を印加して１５μＡの転写電流を流した。
【０２０４】
【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。
【０２０５】
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（結着樹脂Ａ，Ｂ，Ｄ）は溶液重合法により合成し、ポリエステル樹脂（結着樹脂Ｃ）は脱水縮合法により合成した。磁性体の製造方法については以下のとおりである。
【０２０６】
・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とを混合した後、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。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。
・磁性酸化鉄粒子の製造例３
製造例１と同様、ケイ素元素量を変え製造例３の磁性酸化鉄粒子３を得た。
・磁性酸化鉄粒子の製造例４
製造例１と同様、ケイ素元素量を変え製造例４の磁性酸化鉄粒子４を得た。
・磁性酸化鉄粒子の製造例５
製造例１と同様、ケイ素元素量を変え製造例５の磁性酸化鉄粒子５を得た。
【０２０７】
【表１】

【０２０８】
【表２】

【０２０９】
【表３】

【０２１０】

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。
【０２１１】
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６．８μｍのトナー粒子を得た。得られたトナー粒子を、図１０に示す連続的に機械的衝撃力を加える表面処理装置内を通過させる表面処理工程によって、表面処理し本実施例のトナー粒子を得た。
【０２１２】
本実施例では、機械式粉砕機３０１の回転子３１４及び固定子３１０の粉砕面を中心線粗さＲａを５．９μｍ、最大粗さＲｙを３２．４μｍ、十点平均粗さを２１．４μｍとなるように粗面化処理し、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。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４２℃であった。表面処理の具体的な方法としては、各々のローターを周速４０ｍ／ｓで回転させ、ブロアー風量３．０ｍ²に吸引した状態で、オートフィーダーにで毎時２０ｋｇの速度でトナーを供給し１時間運転して表面処理を行った。この時、トナーの処理装置内の通過時間は約２０秒であった。また、この時の装置の排気出口気流温度は４９℃であった。
【０２１３】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム１．０質量部、さら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として２．０質量部混合してトナーＮｏ．１を調製した。
【０２１４】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１の円形度と平均粒子径の関係を図１６（グラフ１）に、トナーＮｏ．１の表面磁性体露出量を示すＵＶスペクトルを図１７（グラフ２）に、トナーのＦＰＩＡ２１００による測定結果の円形度頻度のデータを表４に示す。
【０２１５】
【表４】

【０２１６】
このトナーＮｏ．１を用い、画像形成装置としては、市販のＬＢＰプリンター（ＬＢＰ−２５０，キヤノン社製）からクリーニングユニットを除去し、図１４に示される如きクリーナーレスシステムの画像形成装置に改造した装置を用いて、低温低湿環境下（１５℃，１０％ＲＨ）、常温常湿環境下（２３．５℃，６０％ＲＨ）、高温高湿環境下（３０℃，８０％ＲＨ）でトナーを補給しながら５千枚のプリント試験を行い、画像濃度、かぶり、画質及び帯電部材へのトナー付着の評価を行った。また、熱ロール定着器が用いられているＬＢＰ９５０の定着器を外部へ取り出し、プリンター外でも動作し、定着ローラー温度を任意に設定可能にし、プロセススピードを２３５ｍｍ／ｓとなるように改造した外部定着器を用い、定着性，耐オフセット性の評価を行った。更に、市販のＬＢＰ９５０を用いて転写効率とパターン回収不良の評価を行った。その評価結果を表６〜９に示す。
【０２１７】
定着性
定着性は、ベタ黒画像を１５０℃に温調した定着器に通し、０．４９×１０^-2ＭＰａの荷重をかけ、シルボン紙によりその定着画像を５往復摺擦し、摺擦前後での画像濃度の低下率（％）で評価した。
Ａ：１０％未満
Ｂ：１０％以上、２０％未満
Ｃ：２０％以上
【０２１８】
耐オフセット性
耐オフセット性は、画像面積率約５％のサンプル画像をプリントアウトし、３０００枚後の画像上の汚れの程度により評価した。
Ａ：汚れは見られない。
Ｂ：わずかに汚れが見られる程度である。
Ｃ：画像に影響する汚れ発生している。
【０２１９】
画像濃度、かぶり、画質の評価
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。画質の評価としては、孤立ドット１００個画像形成し、１００個のうち何ドット表すことができたかによって評価する。ドット再現数が多い方が高画質といえるものである。
【０２２０】
これらの評価を、初期、５０００枚時、機外に一日放置した後のそれぞれのタイミングで行った。
【０２２１】
帯電部材へのトナー付着
また、低温低湿環境下で５千枚のプリント試験を行った後、帯電部材へのトナーの付着度合いを評価した。
Ａ：付着が見られない。
Ｂ：わずかに付着が見られる程度である。
Ｃ：ハーフトーン画像上にむらとして現れる程に付着している。
【０２２２】
転写効率
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）で常温常湿環境下で初期及び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。
【０２２３】
パターン回収不良
パターン回収不良については、低温低湿環境下で縦線の同一パターン（２ドット９８スペースの縦線繰り返し）を１万枚連続プリントアウト後、ハーフトーン画像（２ドット３スペースの横線繰り返し）のプリントアウト試験を行い、ハーフトーン画像上に縦線のパターンに対応した濃淡が生じるかどうかを目視で評価した。
Ａ：濃淡は見られない。
Ｂ：わずかに濃淡むらが見られる。
Ｃ：ハーフトーン画像上に濃淡むらが顕著に現れる。
【０２２４】
＜実施例２＞
表５に記載の処方で実施例１と同様にトナーＮｏ．２を作製した。但し、回転子３１４の周速を１２５ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３７℃であった。また、表面処理時の装置の排気出口気流温度は５５℃であった。
【０２２５】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）を１．２質量部とチタン酸ストロンチウム０．８質量部、さら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として２．０質量部混合してトナーＮｏ．２を調製した。
【０２２６】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．２の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２２７】
＜実施例３＞
表５に記載の処方で実施例１と同様にトナーＮｏ．３を作製した。但し、回転子３１４の周速を１１４ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４５℃であった。また、表面処理時の装置の排気出口気流温度は５３℃であった。
【０２２８】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．０質量部とチタン酸ストロンチウム２．０質量部、さら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として２．０質量部混合してトナーＮｏ．３を調製した。
【０２２９】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．３の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２３０】
＜実施例４＞
表５に記載の処方で実施例１と同様にトナーＮｏ．４を作製した。但し、回転子３１４の周速を１５０ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は６３℃であった。また、表面処理時の装置の排気出口気流温度は７２℃であった。
【０２３１】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム０．８質量部、さら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として２．０質量部混合してトナーＮｏ．４を調製した。
【０２３２】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．４の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２３３】
＜実施例５＞
表５に記載の処方で実施例１と同様にトナーＮｏ．５を作製した。但し、回転子３１４の周速を９０ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は３０℃であった。また、表面処理時の装置の排気出口気流温度は３５℃であった。
【０２３４】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム２．４質量部、さら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として２．０質量部混合してトナーＮｏ．５を調製した。
【０２３５】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．５の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２３６】
＜実施例６＞
表５に記載の処方で実施例１と同様にトナーＮｏ．６を作製した。但し、回転子３１４の周速を１１５ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４０℃であった。また、表面処理時の装置の排気出口気流温度は４０℃であった。
【０２３７】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．０質量部とチタン酸ストロンチウム２．４質量部、さら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として２．０質量部混合してトナーＮｏ．６を調製した。
【０２３８】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．６の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２３９】
＜実施例７＞
表５に記載の処方で実施例１と同様にトナーＮｏ．７を作製した。但し、回転子３１４の周速を１３０ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４５℃であった。また、表面処理時の装置の排気出口気流温度は３７℃であった。
【０２４０】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．０質量部とチタン酸ストロンチウム０．４質量部、さらに抵抗が１３０Ω・ｃｍの酸化錫微粉末を導電性微粉末として１．０質量部混合してトナーＮｏ．７を調製した。
【０２４１】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．７の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２４２】
＜実施例８＞
表５に記載の処方で実施例１と同様にトナーＮｏ．８を作製した。但し、回転子３１４の周速を１２５ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４２℃であった。また、表面処理時の装置の排気出口気流温度は４０℃であった。
【０２４３】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．０質量部とチタン酸ストロンチウム０．６質量部、さらに抵抗が１３０Ω・ｃｍの酸化錫微粉末を導電性微粉末として１．０質量部混合してトナーＮｏ．８を調製した。
【０２４４】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．８の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２４５】
＜比較例１＞
表５に記載の処方でトナーＮｏ．１１を作製した。粉砕工程は図８に示した如き衝突式気流粉砕機を用いて行い、得られた粉砕物を第１分級し、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第２分級し、表面処理工程は行わなかった。このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム０．４質量部、さら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として２．０質量部混合してトナーＮｏ．１１を調製した。このようにして得られたトナーの物性値を表５に示し、トナーＮｏ．１１の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２４６】
＜比較例２＞
表５に記載の処方でトナーＮｏ．１２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後の表面処理時の装置の排気出口気流温度は４５℃であった。このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム２．０質量部、さら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として２．０質量部混合してトナーＮｏ．１２を調製した。このようにして得られたトナーの物性値を表５に示し、トナーＮｏ．１２の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２４７】
＜比較例３＞
表５に記載の処方で実施例１と同様にトナーＮｏ．１３を作製した。但し、回転子３１４の周速を１２０ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は４２℃であった。また、分級後の表面処理は行わなかった。
【０２４８】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム１．０質量部、さら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として２．０質量部混合してトナーＮｏ．１３を調製した。
【０２４９】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１３の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２５０】
＜比較例４＞
表５に記載の処方で実施例１と同様にトナーＮｏ．１４を作製した。但し、回転子３１４の周速を１４５ｍ／ｓとして粉砕した。なお、この際、入口温度Ｔ１は−１０℃、出口温度Ｔ２は６０℃であった。また、分級後に得られたトナー粒子を用いて、３００℃の熱風中を瞬間的に通過させる処理を行った。
【０２５１】
この得られたトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム１．０質量部、さら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として２．０質量部混合してトナーＮｏ．１４を調製した。
【０２５２】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１４の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様の試験をした結果を表６〜９に示す。
【０２５３】
＜実施例９＞
実施例４において製造したトナー粒子を用い、このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム０．８質量部を混合してトナーＮｏ．９を調製した。
【０２５４】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．９の円形度と平均粒子径の関係を図１６（グラフ１）に示す。
【０２５５】
このトナーＮｏ．９を市販のＬＢＰプリンター（ＬＢＰ−２１６０，キヤノン社製）を使用して、低温低湿環境、常温常湿環境及び高温高湿環境下で１万枚のプリント試験を行った。さらに、熱ロール定着器が用いられているＬＢＰ９５０の定着器を外部へ取り出し、プリンター外でも動作し、定着ローラー温度を任意に設定可能にし、プロセススピードを２３５ｍｍ／ｓとなるように改造した外部定着器を用い、定着性，耐オフセット性の評価を行った。その評価結果を表１０〜１３に示す。
【０２５６】
定着性
定着性は、ベタ黒画像を１５０℃に温調した定着器に通し、０．４９×１０^-2ＭＰａの荷重をかけ、シルボン紙によりその定着画像を５往復摺擦し、摺擦前後での画像濃度の低下率（％）で評価した。
Ａ：１０％未満
Ｂ：１０％以上、２０％未満
Ｃ：２０％以上
【０２５７】
耐オフセット性
耐オフセット性は、画像面積率約５％のサンプル画像をプリントアウトし、３０００枚後の画像上の汚れの程度により評価した。
Ａ：汚れは見られない。
Ｂ：わずかに汚れが見られる程度である。
Ｃ：画像に影響する汚れ発生している。
【０２５８】
画像濃度、カブリ、画質の評価
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。画質の評価としては、孤立ドット１００個画像形成し、１００個の内何ドット表すことができたかによって評価する。ドット再現数が多い方が高画質といえるものである。
【０２５９】
これらの評価を、初期、１００００枚時、機外に一日放置した後のそれぞれのタイミングで行った。
【０２６０】
転写性評価
市販のＬＢＰプリンター（ＬＢＰ−２１６０，キヤノン社製）を使用して、転写バイアスを２〜２０μＡの間で２μＡ間隔で振って（即ち、２，４，６，８，１０，１２，１４，１６，１８,２０μｍ）、９０ｇ／ｍ²の転写紙を用い、上から３０ｍｍで左右両端から３０ｍｍの位置２箇所及び上から３０ｍｍで中央位置の計３箇所に、５ｍｍ角の正方形（現像量０．８ｍｇ／ｃｍ²）を夫々のトナーを用いて印字した後、転写し、転写率９０％以上を得られる範囲で評価した。
【０２６１】
尚、転写率は、以下のようにして求めた。
【０２６２】
上記のチャート画像を転写紙上に転写して、得られた画像の上にテープを貼り、一方、ドラム上に残った画像をテープではがしとり、それを前記転写紙上に貼り、それぞれの画像濃度をマクベス濃度計で測定する。転写紙上の画像の３箇所の平均濃度をＤ_１、ドラム上に残存した画像の３箇所の平均濃度をＤ_２としたとき、以下の式より求まる値を転写率とする。
【０２６３】
転写率（％）＝Ｄ_１／（Ｄ_１＋Ｄ_２）
Ａ：２〜２０μＡの領域中７点以上の範囲で転写率９０％以上の領域が存在する。
Ｂ：２〜２０μＡの領域中５〜６点の範囲で転写率９０％以上の領域が存在する。
Ｃ：２〜２０μＡの領域中２〜４点の範囲で転写率９０％以上の領域が存在する。
Ｄ：２〜２０μＡの領域中転写率９０％以上の領域が１点以下しか存在しない。
【０２６４】
感光体汚染、クリーニング性評価
キヤノン製ＬＢＰ−２１６０を使用し、トナー消費量が２．５ｇ／Ａ４紙１０００枚となる定量のトナーを現像器から感光体に転移させ続けて、連続２万枚相当、空回転したときの感光体汚染、クリーニング性を１０００枚毎に評価した。感光体汚染は、目視で感光体表面を観察し、感光体表面に融着したトナーで汚染の発生を確認した。クリーニング不良は、目視で感光体表面を観察し、感光体表面の筋状の汚れでクリーニング不良の発生を確認した。尚、２．５ｇ／Ａ４紙１０００枚というトナー消費量は、通常の画像形成における消費量に比べて極めて少量であり、転写効率９５％でベタ画像をプリントアウトしたときの転写残トナーの量に相当する。
Ａ：２万枚相当で発生なし。
Ｂ：１．５〜２万枚相当で発生。
Ｃ：１〜１．５万枚相当で発生。
Ｄ：１万枚相当以下で発生。
【０２６５】
＜実施例１０＞
実施例５において製造したトナー粒子を用い、このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム２．４質量部を混合してトナーＮｏ．１０を調製した。
【０２６６】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１０の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様に試験した結果を表１０〜１３に示す。
【０２６７】
＜比較例５＞
比較例１において製造したトナー粒子を用い、このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム０．４質量部を混合してトナーＮｏ．１５を調製した。
【０２６８】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１５の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様に試験した結果を表１０〜１３に示す。
【０２６９】
＜比較例６＞
比較例４において製造したトナー粒子を用い、このトナー粒子１００質量部に対し、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％で疎水化処理した疎水性シリカ微粉体（メタノールウェッタビリティ８０％，ＢＥＴ比表面積１２０ｍ²／ｇ）１．２質量部とチタン酸ストロンチウム１．０質量部を混合してトナーＮｏ．１６を調製した。
【０２７０】
トナー内添処方，粉砕条件，表面処理条件及び物性値を表５に記し、トナーＮｏ．１６の円形度と平均粒子径の関係を図１６（グラフ１）に示す。また、同様に試験した結果を表１０〜１３に示す。
【０２７１】
【表５】

【０２７２】
【表６】

【０２７３】
【表７】

【０２７４】
【表８】

【０２７５】
【表９】

【０２７６】
【表１０】

【０２７７】
【表１１】

【０２７８】
【表１２】

【０２７９】
【表１３】

【０２８０】
【発明の効果】
本発明によれば、トナー表面に特定の磁性酸化鉄を有し、特定の円形度を有するトナーによって廃トナーの発生が少ない、高転写効率のトナー達成でき、さらに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を説明するため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を実施するため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ためのフローチャートである。
【図８】従来の衝突式気流粉砕機の概略断面図である。
【図９】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１０】本発明で用いた表面処理装置の一例を示す装置システムの概略概観図である。
【図１１】本発明で用いた表面処理装置の概略断面図である。
【図１２】本発明で用いた表面処理装置の回転ローター部分の概略平面図である。
【図１３】本発明で用いた表面処理装置の回転ローター部分の概略断面図である。
【図１４】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該略図である。
【図１５】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該略図である。
【図１６】粒径と円形度の関係（グラフ１）を示す図である。
【図１７】トナー粒子表面から抽出した磁性酸化鉄の吸収スペクトル（グラフ２）を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotography, an image forming method for developing an electrostatic image, and a dry toner used in a toner jet.
[0002]
[Prior art]
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 required for the magnetic toner 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. Further, the chargeability of toner has a great influence on development and transfer, and is closely related to image quality. Therefore, a toner that can stably obtain a high charge amount is desired.
[0003]
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 in many ways, machines are made up of simpler elements. 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.
[0004]
For example, Japanese Patent Application Laid-Open No. 7-230182 and Japanese Patent Application Laid-Open No. 8-286421 propose to stabilize the chargeability by externally adding a magnetic powder. According to this method, it is possible to obtain not only a stable toner with a stable chargeability but also a toner with a high cleaning property. Adhesion to the charging member or the like occurs and is still insufficient.
[0005]
Japanese Patent Laid-Open No. 11-194533 proposes that the alcohol wettability of the magnetic toner is regulated to control the presence state of the magnetic material on the toner surface, and as a result, adhesion to the charging member and the photosensitive drum can be suppressed. However, there is room for improvement with respect to adhesion or fogging to the fixing member in a high-speed machine.
[0006]
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 perform continuous copying promptly, it is necessary to clean the residual toner on the photoreceptor. The collected residual toner is discarded after being put in a container or a collection box installed in the main body or recycled through an appropriate process.
[0007]
To tackle environmental issues, a waste toner-less system with a recycling mechanism inside the main unit 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 fairly large recycling system is required in the main unit. 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.
[0008]
Furthermore, in recent years, the trend of colorization has been rapidly progressing, and in order to achieve high image quality in color images, high transfer efficiency that can withstand multicolor transfer and multiple transfer is required.
[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 It is disclosed that toner volume resistance is reduced by adding / g of hydrophobic silica fine powder, and transfer efficiency is improved by forming a thin film layer with a transfer efficiency improver on the photoreceptor. However, since the toner produced by the pulverization method has a broad particle size distribution, it is difficult to achieve an effect uniformly on all the 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 closer to a sphere, and as a method there are toners produced by a production method such as a spray granulation method, a solution dissolution method, or a polymerization method. No. 3-229268, JP-A-4-1766, JP-A-4-102862, and the like. However, in addition to requiring large-scale equipment for the production of these toners, there are problems associated with cleaning because the toner approaches the true sphere, which is preferable for the purpose of improving the transfer efficiency only. It's not a method.
[0012]
Furthermore, in JP-A-2-87157, JP-A-11-149176, and JP-A-11-202557, the shape and surface properties of the toner produced by the pulverization method are modified by thermal or mechanical impact. A method for improving transfer efficiency by improving the quality is disclosed. However, the transfer efficiency is still inadequate in a system for achieving multifunctional and high-speed copying machines, printers and facsimiles required in the market, high-quality copy images, and miniaturization of machines. .
[0013]
Japanese Patent Application Laid-Open No. 11-65163 discloses a method of achieving a cleaner-less system by controlling toner shape factor by mixing toners having two types of shapes. However, since toners having different shapes are mixed, a shape distribution is generated. Therefore, this method needs to be improved in order to achieve higher image quality and smaller size.
[0014]
In general, as a method for producing a toner, a binder resin for fixing to a transfer material, various colorants for producing a color as a toner, a charge control agent for imparting electric charge to particles, or JP In the so-called one-component development method as shown in Japanese Patent Laid-Open No. 54-42141 and Japanese Patent Laid-Open No. 55-18656, in addition to these, various magnetic materials for imparting transportability and the like to the toner itself are used. Furthermore, if necessary, for example, other additives such as a release agent and a fluidity-imparting agent are added and dry-mixed, and then melt-kneaded in a general-purpose kneading apparatus such as a roll mill or an extruder, and then solidified by cooling. The kneaded product is refined by various pulverizers such as a jet airflow pulverizer and a mechanical collision pulverizer, and the obtained finely pulverized product is introduced into various wind classifiers and classified to be necessary as a toner. Give aligned radially classified product, further, the fluidizing agent or lubricant, etc. was externally added by dry-mixing as necessary, and the toner to be subjected to image formation. In the case of a toner used in the two-component development method, various magnetic carriers and the above toner are mixed and then used for image formation.
[0015]
As described above, in order to obtain toner particles that are fine particles, conventionally, the method shown in the flowchart of FIG. 7 is generally employed.
[0016]
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.
[0017]
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.
[0018]
Various pulverizers are used as the pulverizing means. For the pulverization of the toner crushed material mainly composed of the binder resin, a jet airflow pulverizer using a jet airflow as shown in FIG. 8, particularly a collision airflow pulverizer. Is used.
[0019]
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.
[0020]
For example, in the collision-type airflow crusher shown in FIG. 8, the collision member 164 is provided opposite to 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 acceleration tube 162 from the powder raw material supply port 165 communicated in the middle, and the powder raw material is ejected together with the high-pressure gas, and collides with the collision surface 166 of the collision member 164 in the crushing chamber 168. And pulverized by the impact, and the pulverized product is discharged from the pulverized product discharge port 167.
[0021]
However, the collision type airflow pulverizer is configured such that the powder raw material is jetted together with the high-pressure gas, collides with the collision surface of the collision member, and is pulverized by the impact, so the pulverized toner is irregular and angular. As a result, the release agent and magnetic powder from the toner easily fall off.
[0022]
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 of devices has been demanded in response to environmental problems.
[0023]
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.
[0024]
As shown in FIG. 9, these airflow classifiers eject powder together with airflow at high speed from a supply nozzle having an opening in the classification area of the classifier room, and the Coanda block 145 is placed in the classification room. It is separated into coarse powder (158), medium powder (159), and fine powder (160) by the centrifugal force of the curved airflow that flows along the edges 146, 147 whose tips are narrowed. , Classification of fine powder.
[0025]
In the conventional classifier, 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 straightly with a propulsive force parallel to the tube wall. However, the raw material supply nozzle is roughly 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. Therefore, depending on the introduction site into the classifier, different trajectories are drawn, and coarse powder disturbs the fine powder trajectory, so there is a limit in improving classification accuracy, and coarse particles of 20 μm or more. There was a tendency for accuracy to be reduced in classification of powders with a large amount.
[0026]
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.
[0027]
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.
[0028]
In particular, when a toner having a sharp particle size distribution with a weight average particle size of 10 μm or less is to be obtained, 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 particle size 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.
[0029]
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.
[0030]
Further, in the finely divided toner, the colorant (magnetic material) contained in the toner is relatively increased, and the released magnetic material is increased accordingly. For this reason, it becomes difficult to maintain the low-temperature fixability of the toner in response to the simplification and speeding up of the machine, which will be further required in the future, and the developability is also more severely restricted than before.
[0031]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner that solves the above problems.
[0032]
An object of the present invention is to provide a toner having a high transfer efficiency with little generation of waste toner and a method for producing the same.
[0033]
It is another object of the present invention to provide an image forming method and a process cartridge that can achieve a cleaner-less system.
[0034]
[Means for Solving the Problems]
The present invention relates to a toner having toner particles containing at least a binder resin and magnetic iron oxide, wherein the toner has a weight average particle diameter of 4 to 12 μm, and particles of 3 μm or more of the toner have the following formula (1 )
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value Y ≧ exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
The present invention relates to a dry toner characterized by having an absorbance at a wavelength of 340 nm of 1.0 to 2.5 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes.
[0035]
Further, the present invention is obtained by melt-kneading a mixture having at least a binder resin and magnetic iron oxide, cooling the obtained kneaded product, and then pulverizing the cooled product by a pulverizing means to obtain a finely pulverized product. A method for producing a toner comprising classifying finely pulverized products to obtain toner particles, and further producing a toner through a surface treatment step of surface treating the toner particles,
The crushing means includes a rotor that is a rotating body attached to at least a central rotating shaft, and a stator that is arranged around the rotor while maintaining a certain distance from the surface of the rotor. Is a mechanical crusher that performs crushing while holding
The surface treatment step is a step of performing surface treatment by passing toner particles through a surface treatment apparatus that continuously applies mechanical impact force.
In the toner having a weight average particle diameter of 4 to 12 μm and particles of 3 μm or more of the toner, the following formula (1)
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value Y ≧ exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
The present invention relates to a method for producing a dry toner, characterized in that an absorbance at a wavelength of 340 nm is 1.0 to 2.5 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes.
[0036]
The present invention also provides a latent image forming step of forming an electrostatic charge image on the electrostatic charge image holding member; developing the electrostatic charge image held on the electrostatic charge image holding member with toner to form a toner image. Image forming comprising at least: a developing step; a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member; and a fixing step of fixing the toner image transferred to the transfer material to the transfer material A method,
The developing step also serves to form the toner image and collect the developer remaining on the electrostatic charge image holding member after the toner image is transferred to the transfer material.
The developer is a toner having toner particles containing at least a binder resin and magnetic iron oxide, the toner has a weight average particle diameter of 4 to 12 μm, and the toner having a particle size of 3 μm or more is represented by the following formula ( 1)
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value Y ≧ exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 (2)
[However, toner weight average particle diameter X: 4.0 to 12.0 μm]
Satisfied,
The present invention relates to an image forming method characterized in that an absorbance at a wavelength of 340 nm is 1.0 to 2.5 in a solution in which 5 ml of 3 mol / l hydrochloric acid is added to 20 mg of the toner and left for 50 minutes.
[0037]
Furthermore, the present invention is a process cartridge that can be attached to and detached from the main body of the image forming apparatus, and the process cartridge uses at least an electrostatic charge image holding member and an electrostatic charge image formed on the electrostatic charge image holding member with toner. And developing means for forming a toner image.
The developing means forms the toner image and collects toner remaining on the electrostatic image holding member after the toner image is transferred to a transfer material.
The toner has toner particles containing at least a binder resin and magnetic iron oxide, the toner has a weight average particle diameter of 4 to 12 μm, and particles having a particle size of 3 μm or more are represented by the following formula (1): )
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value Y ≧ exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
The present invention relates to a process cartridge characterized in that an absorbance at a wavelength of 340 nm is 1.0 to 2.5 in a solution in which 5 ml of 3 mol / l hydrochloric acid is added to 20 mg of the toner and left for 50 minutes.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors proceeded with studies on the shape of the toner produced by the pulverization method and the amount of magnetic iron oxide present on the toner surface, and the shape of the toner particles of 3 μm or more and the amount of magnetic iron oxide present on the toner surface are transferable. It has been found that there is a close relationship with developability, in particular, the rising speed of charging, and by controlling these, a cleanerless image forming method is possible even with toner by a pulverization method. Furthermore, it has been found that this can be achieved by an unprecedented method by using a pulverization / classification / surface treatment system that optimally produces the toner.
[0039]
That is, the present inventors have at least a binder resin and magnetic iron oxide, and in a solution in which 5 ml of 3 mol / l hydrochloric acid is added to 20 mg of the toner and left for 50 minutes, the absorbance at a wavelength of 340 nm is 1.0 to 2. .5, and more preferably, the toner having an absorbance at a wavelength of 340 nm of 1.3 to 2.3 and having a circularity distribution in a specific range can improve transfer efficiency without impairing fixability. The present inventors have found that high image quality can be stably obtained even when used under high and low humidity, and no image defect occurs during durability.
[0040]
When 3 mol / l hydrochloric acid is added to the toner and allowed to stand for 50 minutes, components dissolved in hydrochloric acid existing on the toner surface and in the vicinity of the surface are extracted into the hydrochloric acid. In magnetic toners containing magnetic iron oxide, the main component extracted is magnetic iron oxide. In addition, if the charge control agent or colorant used is soluble in hydrochloric acid, these are also extracted. However, since the content of magnetic iron oxide is usually much higher than other components, most of the extracted components are derived from magnetic iron oxide.
[0041]
Moreover, in this invention, although the light absorbency in wavelength 340nm of the component extracted with hydrochloric acid is measured, this wavelength is a wavelength which iron absorption appears mainly. That is, the absorbance at a wavelength of 340 nm of a component obtained by extracting the toner with 3 mol / l hydrochloric acid for 50 minutes is derived from the magnetic iron oxide existing near the toner surface and the extreme surface. By comparing this value, Then, the existence ratio of magnetic iron oxide in the vicinity of the toner surface can be estimated.
[0042]
When the absorbance at a wavelength of 340 nm is larger than 2.5, this indicates that a large amount of magnetic iron oxide is exposed on the surface of the toner particles. When the amount of magnetic iron oxide exposed to the toner surface is large, the magnetic iron oxide is likely to be missing from the toner particles, and this free magnetic iron oxide makes it difficult for the toner to be cleaned well by the cleaning member. A phenomenon in which the toner adheres to the charging member under low temperature and low humidity and a phenomenon in which the toner is pressed by the charging member and adheres to the surface of the photosensitive drum under high temperature and high humidity are likely to occur. If toner adheres to the surface of the charging member or the photosensitive drum in this way, charging control becomes unstable, and as a result, developability tends to be adversely affected. Furthermore, the toner charge is likely to leak through the exposed magnetic iron oxide, resulting in a decrease in the toner charge amount. In addition, a toner with a low charge amount causes an increase in fog and has a low transfer efficiency and causes further charging failure, which adversely affects developability. Furthermore, since such a toner has a non-uniform dispersion state of magnetic iron oxide in the toner, the chargeability becomes non-uniform, and a problem arises in the rise of image density especially in image output under low temperature and low humidity. It is easy to end.
[0043]
On the other hand, when the absorbance at a wavelength of 340 nm derived from the magnetic iron oxide is smaller than 1.0, this indicates that the magnetic iron oxide is hardly exposed on the toner particle surface. Toner with almost no exposure of magnetic iron oxide to the toner surface has a high charge amount, but 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. As a result, the image density may decrease. Further, with such a toner, a toner having a high charge amount can be obtained, but the toner layer on the image becomes denser and dot reproducibility is lowered. That is, the image quality is deteriorated such that the toner is scattered, tailing occurs, or the line width becomes too thick.
[0044]
That is, in a solution obtained by extracting surface magnetic iron oxide in 20 mg of toner with 5 ml of 3 mol / l hydrochloric acid for 50 minutes, the absorbance at a wavelength of 340 nm is controlled in the range of 1.0 to 2.5, whereby a charging member or a photosensitive drum is obtained. In addition, the toner can be prevented from adhering to the toner, and it is easy to control the charge, and a toner having excellent charge uniformity and charge durability and stability can be obtained.
[0045]
The absorbance of the present invention is the intensity of incident light I when light is incident on the sample cell. ₀ And the transmittance I / I which is the ratio of the transmitted light intensity I ₀ The common logarithm of the reciprocal of i.e. log (I ₀ / I).
[0046]
The amount of magnetic iron oxide present on the toner particle surface in the present invention is determined as follows.
[0047]
<Measurement of the amount of magnetic iron oxide on the toner surface>
1) Weigh the toner (20 mg) precisely.
2) Put a sample in a sample bottle, add 5 ml of 3 mol / l hydrochloric acid, and leave it in a normal temperature and humidity environment (23.5 ° C., 60% RH) for 50 minutes.
3) The solution after standing was filtered with a sample processing filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation)), and the filtrate was spectrophotometrically measured. Measured by a meter (for example, Shimadzu UV-3100PC). At this time, 3 mol / l hydrochloric acid not dissolving the toner is put in the control cell.
[0048]
Measurement conditions: scan speed (medium speed), slit width (0.5 nm), sampling pitch (2 nm), measurement range (600 to 250 nm)
[0049]
The circularity in the present invention is used as a simple method for quantitatively expressing the particle shape. In the present invention, the circularity is measured by using a flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation. The circularity of the obtained particles is obtained by the following equation (1), and the value obtained by dividing the total circularity of all particles measured by the following equation (2) by the total number of particles is defined as the average circularity.
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
“512 × 512 image processing resolution (0.3 μm × 0.3 μm pixel)” means that 512 pixels of 0.3 μm square are arranged as a visual field for measurement. .
[0050]
[Outside 1]

(2)
[Where the circularity of each particle is a _i And the number of measured particles is m. ]
[0051]
The circularity used in the present invention is an index of the degree of unevenness of the toner particles, and indicates 1.000 when the toner is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.
[0052]
In addition, “FPIA-2100”, 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. A calculation method is used in which the degrees of 0.4 to 1.0 are divided into classes divided into 61 in increments of 0.010, and the average circularity and circularity standard deviation are calculated using the center value and frequency of the dividing 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.
[0053]
Furthermore, “FPIA-2100”, which is a measuring apparatus used in the present invention, has a sheath flow (of CCD camera and strobe) compared with “FPIA-1000” which has been conventionally used for calculating the shape of toner. (Thickness of the cell when the sample solution flows between them) (7 μm → 4 μm), the magnification of the processed particle image is improved, and the processing resolution of the captured image is improved (256 × 256 → 512 × 512). The accuracy of the shape measurement is improved, thereby achieving more reliable analysis of fine particles. Therefore, when it is necessary to measure the shape more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape more accurately is more useful. With FPIA-1000, the smaller the particle size, the more difficult it is to capture the contour of the particle, and the higher the circularity, that is, the tendency to be more round.
[0054]
As a specific method for measuring the circularity, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant in 100 to 150 ml of water from which impurities in the container have been removed in advance, and further measured. Add about 0.1-0.5g of sample. 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 3.00 μm or more and less than 159.21 μm is measured.
[0055]
The outline of the measurement is as follows.
[0056]
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.
[0057]
Conventionally, it has been known that the toner shape affects various characteristics of the toner. However, the present inventors have made various studies on the toner shape of 3 μm or more and the amount of magnetic iron oxide exposed on the toner surface. It has been found that transferability and developability are greatly affected, and by controlling these, a developing and cleaning method and a cleanerless image forming method can be satisfactorily realized with toner by a pulverization method. In the development and cleaning method and the cleanerless image forming method, the charge polarity and charge amount of the transfer residual toner particles on the photoconductor are controlled, and the transfer residual toner particles are stably recovered in the development process. The point is not to make it worse, and when the toner according to the present invention is used, these are satisfactorily achieved.
[0058]
The toner of the present invention has the following formula (1) in the particles of 3 μm or more of the toner.
Circularity a = L ₀ / L (1)
[Where L ₀ Indicates the perimeter of a circle having the same projected area as the particle image, and L indicates the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). ]
Further, the number-based cumulative value Y of particles having a circularity a of 0.900 or more and a number-based cumulative value of 85% or more, and a circularity of 0.950 or more and the weight average particle diameter X of the toner. Is the following formula (2)
Number-based cumulative value Y ≧ exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Is satisfied.
[0059]
When the toner has such a circularity, it is easy to control the charge, and it is possible to obtain a toner with excellent charge uniformity and stable charge durability. Therefore, even after the transfer residual toner is collected from the photoreceptor. The chargeability of the collected toner is also stable, and charging can be controlled when developing again. Further, when such circularity is provided, the contact area between the toner particles and the photosensitive member is reduced, and the adhesion force of the toner particles to the photosensitive member due to van der Waals force or the like is reduced, so that the transfer efficiency is increased. . Furthermore, since the specific surface area of the toner particles is reduced compared to a general pulverized toner, the contact area between the toner particles is reduced, the bulk density of the toner powder becomes dense, and heat conduction during fixing is reduced. It can be improved, and the effect of improving the fixing property can also be obtained.
[0060]
When the presence of particles having a circularity a of 0.900 or more in particles of 3 μm or more of the toner is less than 85% in terms of the number-based cumulative value, contact between the toner particles and the developer carrying member, the photosensitive member, etc. Since the area increases, toner charge leakage is likely to occur through a portion in contact with the developer carrying member, the photosensitive member, and the like, and as a result, the toner charge amount may decrease. In addition, the contact area between the toner particles and the photoconductor increases, and the adhesion force of the toner particles to the photoconductor increases, making it difficult to obtain sufficient transfer efficiency.
[0061]
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner in particles of 3 μm or more of the toner is expressed by the following formula:
Number based cumulative value Y <exp5.31 × X of particles having a circularity of 0.950 or more ^-0.715 [However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
In such a case, not only the fluidity of the toner is inferior, but also not only a sufficient transfer efficiency cannot be obtained, but also the desired fixing performance is difficult to obtain.
[0062]
The toner of the present invention has a weight average particle diameter of 4 to 12 μm. More preferably, the toner has a weight average particle size 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. Is good.
[0063]
The toner having a weight average particle diameter exceeding 12 μm has an angular shape, making it difficult to achieve a predetermined circularity and further difficult to achieve a predetermined circularity distribution.
[0064]
Toners with a weight average particle size of less than 4 μm have a shape that is too close to a sphere, or the spheroidization due to heat progresses and the surface is coated with magnetic iron oxide. It is difficult to control both the amount and the generation of fine powder and super fine powder.
[0065]
A toner with a particle size of 4.0 μm or less exceeding 40% by number tends to be too close to a sphere or is easily spheroidized by heat and coated with magnetic iron oxide on the surface, and the circularity distribution And the amount of magnetic iron oxide near the surface are difficult to control.
[0066]
A toner having a particle size of 10.1 μm or more exceeding 25% by volume tends to have an angular shape, so that it is difficult to achieve a predetermined circularity, and it is difficult to control the circularity distribution.
[0067]
As one guideline representing such particle variation, the circularity standard deviation SD obtained from the following equation can also be used. In the present invention, there is no problem if the circularity standard deviation SD is 0.030 to 0.065.
[0068]
[Outside 2]

[0069]
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.
[0070]
Without such an acid value range, the dispersibility of the toner raw material, especially magnetic iron oxide particles, is reduced in the kneading step during toner production, and the degree of exposure of the magnetic iron oxide to the toner surface by the pulverization and surface treatment steps Is difficult to control within a predetermined range. In addition, when the acid value of the binder resin is less than 1 mgKOH / g, the chargeability of the toner particles is lowered, and the developability and durability stability are likely to be inferior. 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.
[0071]
In the present invention, the acid value of the binder resin is determined by the following method.
[0072]
<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 0.1 mol / l KOH methanol solution, titration is performed using a potentiometric titrator (for example, a potentiometric titrator AT-400 (winworkstation) manufactured by Kyoto Electronics Co., Ltd.) and an ABP-410 electric burette. Automatic titration can be used.)
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.
Acid value (mgKOH / g) = ((SB) × f × 5.61) / W
[0073]
As the binder resin used in the toner of the present invention, the following binder resins can be used.
[0074]
For example, styrene and its substituted homopolymers such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol Resin, natural modification Enol resin, natural resin-modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin ， Petroleum resin can be used. Preferred binder materials include styrene copolymers or polyester resins.
[0075]
Examples of the comonomer for the styrene monomer of the styrene-based copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or its substitutes; for example, maleic acid, butyl maleate, maleic acid Dicarboxylic acids having a double bond such as methyl and dimethyl maleate and their substitutes; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; for example, ethylene, propylene and butylene Vinyl monomers such as ethylene olefins; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; It is done.
[0076]
The styrenic polymer or styrenic copolymer may be cross-linked or a mixed resin thereof.
[0077]
The binder resin according to the present invention has a glass transition temperature (Tg) of 45 to 75 ° C., preferably 50 to 70 ° C. from the viewpoint of storage stability, and if the 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 Tg exceeds 75 ° C., the fixability tends to be lowered.
[0078]
As the magnetic material used in the present invention, magnetic iron oxides such as magnetite, maghemite, and ferrite are used, and those containing non-ferrous elements on or inside the magnetic iron oxide are preferable.
[0079]
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 It is preferably a magnetic iron oxide containing at least one element selected from silver, palladium, gold, mercury, platinum, tungsten, molybdenum, niobium, osmium, strontium, yttrium, technetium, ruthenium, rhodium, and bismuth. . In particular, lithium, beryllium, boron, magnesium, aluminum, silicon, phosphorus, germanium, zirconium, and tin are preferable elements. These elements may be incorporated into the iron oxide crystal lattice, may be incorporated into the iron oxide as oxides, or may exist on the surface as oxides or hydroxides. Moreover, it is a preferable form to contain as an oxide.
[0080]
Further, the amount contained in the toner is preferably 20 to 200 parts by mass with respect to 100 parts by mass of the resin component, and more preferably 40 to 150 parts by mass with respect to 100 parts by mass of the resin component.
[0081]
Other colorants that can be used in the toner include any suitable pigment or dye. 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. .
[0082]
The waxes used in the present invention include the following. 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 compounds It is.
[0083]
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 a catalyst such as a Ziegler catalyst or a metallocene catalyst under low pressure. Polyolefins; Polyolefins polymerized using radiation, electromagnetic waves or light; Low molecular weight polyolefins obtained by thermally decomposing high molecular weight polyolefins; Paraffin wax, microcrystalline wax, Fuchsia-Tropsch wax; Jindole method, Hydrocol method, Age method Synthetic hydrocarbon waxes synthesized by, etc .; synthetic waxes using a compound having one carbon atom as a monomer, hydrocarbon waxes having a functional group such as a hydroxyl group or a carboxyl group; hydrocarbon waxes having a functional group That a mixture of waxes; styrene these waxes as a matrix, maleic acid ester, acrylate, methacrylate, wax graft-modified with such vinyl monomers of maleic acid.
[0084]
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.
[0085]
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 to 120 ° C. in order to balance the fixability and the offset resistance. It is preferable that 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.
[0086]
In the toner of the present invention, the total wax content is 0.2 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the binder resin. is there. Further, a plurality of waxes may be used in combination as long as they do not have an adverse effect.
[0087]
In the present invention, 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.
[0088]
In the present invention, the DSC measurement using a differential scanning calorimeter for wax or toner is preferably performed using a differential scanning calorimeter with high accuracy of internal heat input compensation. For example, DSC-7 manufactured by Perkin Elmer can be used.
[0089]
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.
[0090]
In the dry toner of the present invention, conventionally known pigments or dyes such as carbon black and copper phthalocyanine can be used as coloring materials that can be added.
[0091]
In the present invention, it is preferable to add and use a charge control agent. Specific examples of the negative charge control agent include monoazo dyes described in JP-B No. 41-20153, JP-B No. 42-27596, JP-B No. 44-6397, JP-B No. 45-26478, and the like. 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, etc. Examples thereof include metal complexes of Zn, Al, Co, Cr, Fe, and Zr of acids, sulfonated copper phthalocyanine pigments, styrene oligomers introduced with nitro groups and halogens, and chlorinated paraffins. An azo metal complex represented by the general formula (I) or a basic organic acid metal complex represented by the general formula (II), which is particularly excellent in dispersibility and is effective in reducing image density stability and fogging. Is preferred.
[0092]
[Outside 3]

[0093]
[Wherein M represents a coordination center metal and represents Cr, Co, Ni, Mn, Fe, Ti, or Al. Ar is an aryl group such as a phenyl group or a naphthyl group, and may have a substituent. In this case, examples of the substituent include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxy group having 1 to 18 carbon atoms. X, X ′, Y, Y ′ are —O—, —CO—, —NH—, —NR— (R is an alkyl group having 1 to 4 carbon atoms). A ⁺ Represents hydrogen ion, sodium ion, potassium ion, ammonium ion or aliphatic ammonium ion. ]
[0094]
[Outside 4]

[0095]
[Wherein M represents a coordination center metal, and represents Cr, Co, Ni, Mn, Fe, Ti, Zr, Zn, Si, B, or Al. (B)
[Outside 5]

[0096]
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.
[0097]
[Outside 6]

[0098]
[Where X ₂ And X _Three Represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom, k and k ′ represent an integer of 1 to 3, Y ₁ And Y _Three Is a hydrogen atom, C ₁ ~ C ₁₈ Of alkyl, C ₂ ~ C ₁₈ Alkenyl, sulfonamide, mesyl, sulfonic acid, carboxy ester, hydroxy, C ₁ ~ C ₁₈ Represents an alkoxy group, an acetylamino group, a benzoyl group, an amino group or a halogen atom, and l and l ′ represent an integer of 1 to 3, ₂ And Y _Four Represents a hydrogen atom or a nitro group, and the above X ₂ And X _Three , K and k ', Y ₁ And Y _Three , L and l ', Y ₂ And Y _Four May be the same or different, A ^{'' +} Represents ammonium ion, sodium ion, potassium ion, hydrogen ion or a mixed ion thereof, and preferably has 75 to 98 mol% of ammonium ion. ]
[0099]
[Outside 7]

[0100]
[Wherein R ₁ ~ R ₂₀ Represents hydrogen, halogen or an alkyl group, and A ⁺ Represents ammonium ion, sodium ion, potassium ion, hydrogen ion or a mixed ion thereof. ]
[0101]
Next, specific examples of the azo iron complex represented by the above formula (III) are shown.
[Outside 8]

[0102]
[Outside 9]

[0103]
Specific examples of the charge control agent represented by the above formulas (I), (II), and (IV) are shown below.
[0104]
[Outside 10]

[0105]
[Chemical 1]

[0106]
[Outside 11]

[0107]
These metal complex compounds can be used alone or in combination of two or more.
[0108]
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.
[0109]
On the other hand, there are the following substances that control the toner to be positively charged.
[0110]
Modified products with nigrosine and fatty acid metal salts, etc., quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs such as oniums such as phosphonium salts Salts and their lake pigments, triphenylmethane dyes and their lake pigments A metal salt of a higher fatty acid; a diorganotin oxide such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicis Diorgano tin borate such such as Russia hexyl tin borate; can be used in combination singly, or two or more kinds.
[0111]
The magnetic toner of the present invention is preferably mixed with inorganic fine powder or hydrophobic inorganic fine powder. For example, it is preferable to add and use silica fine powder.
[0112]
As the silica fine powder used in the present invention, both a so-called dry method produced by vapor phase oxidation of a silicon halogen compound or a so-called wet silica produced from water glass or the like, or dry silica called fumed silica can be used. However, dry silica with less silanol groups on the surface and inside and no production residue is preferred.
[0113]
Further, the silica fine powder used in the present invention is preferably hydrophobized. The hydrophobizing treatment is performed by chemically treating with an organosilicon compound that reacts or physically adsorbs with silica fine powder. Preferable methods include a method in which a dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound is treated with a silane compound or with a silane compound and simultaneously with an organosilicon compound such as silicone oil.
[0114]
Examples of the silane compound used for the hydrophobization treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyl. Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxy Silane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyl Examples include tildisiloxane and 1,3-diphenyltetramethyldisiloxane.
[0115]
Examples of the organosilicon compound include silicone oil. A preferred silicone oil has a viscosity of approximately 3 × 10 at 25 ° C. ^-Five ~ 1x10 ^-3 m ² For example, dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, α-methyl styrene modified silicone oil, chlorophenyl silicone oil, and fluorine modified silicone oil are preferable.
[0116]
Silicone oil treatment may be performed by, for example, mixing silica fine powder treated with a silane compound and silicone oil directly using a mixer such as a Henschel mixer, or by spraying silicone oil onto the base silica. Also good. 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.
[0117]
Further, in the present invention, it is preferable that 5 to 300 conductive fine powders having a particle diameter of 0.6 to 3.0 μm per 100 toner particles is used in the cleanerless image forming method. The conductive fine powder having a particle size of 0.6 to 3.0 μm is easily separated from the toner particles and easily behaves. The conductive fine powder adheres uniformly to the charging member and is stably held. By having 5 to 300 toner particles per 100 toner particles, the chargeability can be made uniform in the development process and the transfer process. Further, by having 5 to 300 conductive fine powders having a particle diameter of 0.6 to 3 μm per 100 toner particles in the toner, the recoverability of the transfer residual toner particles in the developing and cleaning process is further stabilized.
[0118]
Examples of the conductive fine powder in the present invention include carbon fine powder such as carbon black and graphite; metal fine powder such as copper, gold, silver, aluminum and nickel; zinc oxide, titanium oxide, tin oxide, aluminum oxide and indium oxide. , Silicon oxide, magnesium oxide, barium oxide, molybdenum oxide, iron oxide, metal oxides such as tungsten oxide; metal compounds such as molybdenum sulfide, cadmium sulfide, potassium titanate; or the number of primary particles of these composite oxides A conductive fine powder having an average particle size of 50 to 500 nm and having an aggregate of primary particles can be used, and a conductive fine powder having an adjusted particle size distribution is used to adjust the particle size and particle size distribution as a toner. Is also preferable.
[0119]
In addition, other external additives may be added to the magnetic toner in the present invention as necessary. For example, there are resin fine particles and inorganic fine particles that act as a charging aid, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a lubricant, and an abrasive.
[0120]
For example, lubricants such as Teflon (R), zinc stearate, and polyvinylidene fluoride are preferable, and among them, polyvinylidene fluoride is preferable. Alternatively, an abrasive such as cerium oxide, silicon carbide, or strontium titanate, and particularly strontium titanate is preferable. Alternatively, fluidity imparting agents such as titanium oxide and aluminum oxide, and particularly hydrophobic ones are preferable. A small amount of an anti-caking agent, or a conductivity imparting agent such as carbon black, zinc oxide, antimony oxide or tin oxide, or fine particles charged in the opposite polarity can be used in small amounts.
[0121]
The external additive mixed with the magnetic 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 magnetic toner.
[0122]
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 process, and is characterized in that the pulverization step and the classification step are performed in one pass.
[0123]
In the toner manufacturing method of the present invention, the degree of exposure of the magnetic iron oxide on the toner surface is controlled to some extent by manufacturing a toner having a specific circularity. In the present invention, a coarsely pulverized product obtained by melt-kneading a mixture containing at least a binder resin, magnetic iron oxide and wax, cooling the obtained kneaded product, and then pulverizing the cooled product by a coarse pulverizing means Is used as a powder raw material. First, a predetermined amount of pulverized raw material, a rotor that is a rotating body attached to at least a central rotating shaft, and a stator that is arranged around the rotor while maintaining a predetermined distance from the rotor surface The material to be pulverized is finely pulverized by rotating the rotor of the mechanical pulverizer at a high speed. Next, the finely pulverized pulverized raw material is introduced into a classification step and classified to obtain a classified product as a toner raw material including 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 step using such a classifier, the coarse powder composed of a particle group having a particle size larger than the preferred particle size and the ultrafine powder composed of a particle group having a particle size less than the preferred particle size are excluded. Thereafter, a desired toner powder is obtained by continuously passing the obtained intermediate powder through a surface treatment apparatus that applies mechanical impact force, and is used as a toner product as it is, or hydrophobic silica And then used as a toner.
[0124]
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.
[0125]
FIG. 2 shows an example of an apparatus system to which the toner manufacturing method of the present invention is applied, and the present invention will be described more specifically based on this. 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 a colorant and a wax is melt-kneaded, the obtained kneaded product is cooled, and the cooled product is coarsely pulverized by a pulverizing means.
[0126]
In this apparatus system, a pulverized raw material serving as a toner powder raw material is first introduced into a mechanical pulverizer 301 serving as a pulverizing unit via a first fixed amount feeder 315. 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.
[0127]
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 from the viewpoint of toner productivity and production efficiency. .
[0128]
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 includes a multi-split airflow classifier 1 (classifying apparatus shown in FIG. 6), a quantitative feeder 2, a vibration feeder 3, a collecting cyclone 4, a collecting cyclone 5, and a collecting cyclone 6. They are connected by communication means.
[0129]
In this apparatus system, the powder is fed into the fixed amount feeder 2 by an appropriate means, and then introduced into the multi-split airflow 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 multi-split airflow classifier 1 is usually [10-50 cm] × [10-50 cm], the powder is instantly three or more types of particles in 0.1 to 0.01 seconds or less. Can be classified into groups. And it classify | categorizes into a big particle (coarse particle), an intermediate | middle particle | grain, and a small particle | grain with the multi-division airflow classifier 1. FIG. Thereafter, the large particles are sent to the collecting cyclone 6 through the discharge conduit 11a 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, collected by the collecting cyclone 4, and supplied to the melt-kneading process for producing a powder raw material made of the toner material for reuse or disposal. Is done. The collecting cyclones 4, 5, 6 can also function as a suction pressure reducing means for sucking and introducing the powder into the classification chamber through 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. The inlet pipes 14 and 15 for introducing gas into the classifier 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.
[0130]
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.
[0131]
In this apparatus system, the particle size of the powder raw material is 95% by mass or more of particles that pass through a sieve having an opening of 1000 μm (18 mesh pass (ASTME-11-61)), and particles that cannot pass through a sieve having an opening of 150 μm. (100 mesh on (ASTME-11-61)) is preferably 90% by mass or more.
[0132]
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 finely pulverized product finely pulverized by a mechanical pulverizer is used. The diameter is 4 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.
[0133]
In the apparatus system to which the toner manufacturing method of the present invention is applied, the first classification step before the fine pulverization process is not required, and the pulverization step and the classification step can be performed in one pass.
[0134]
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., a turbo mill manufactured by Turbo Industry Co., Ltd., and the like, and these devices are preferably used as they are or after being appropriately modified.
[0135]
In the present invention, among these, it is easy to manufacture toner using a mechanical pulverizer as shown in FIGS. 3, 4 and 5 to facilitate the toner shape and the amount of magnetic iron oxide exposed on the toner surface. It is preferable as a method that can be controlled and manufactured. Furthermore, since the powder raw material can be easily pulverized, efficiency is improved, which is preferable.
[0136]
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 is likely to be generated at the time of the collision. Furthermore, since the pulverized toner becomes irregular and angular, exposure of the magnetic iron oxide particles from the toner increases. In addition, it is possible to modify the shape and surface properties of the toner produced by collision-type airflow pulverization by mechanical impact (hybridizer), but it achieves a circularity sufficient to exert the effect of the present invention. In order to achieve this, it is necessary to modify the shape of the particles by heat to bring the shape closer to a sphere, and it is difficult to control the amount of magnetic iron oxide exposed to the toner surface.
[0137]
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 used in the present invention, and FIG. 4 shows a schematic cross-sectional view along the line DD ′ in FIG. These show the perspective view of the rotor 314 shown in FIG. 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 is arranged at a constant interval, 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.
[0138]
The pulverization operation in the mechanical pulverizer configured as described above is performed, for example, 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 raw material discharge port 302, the pipe 219, the collecting cyclone 229, the bag filter 222, and the suction blower 224. Is done. In the present invention, since the powder raw material is pulverized, a desired pulverization process can be easily performed without increasing fine powder and coarse powder. In addition, 240 is a powder raw material hopper, 315 is a 1st fixed supply machine.
[0139]
Further, when the pulverized raw material is pulverized by a mechanical pulverizer, the cold air generating means 321 blows cold air into the mechanical pulverizer together with the powder raw material so that the mechanical pulverizer body has a jacket 316 and is cooled. By passing water (preferably an antifreeze such as ethylene glycol), the atmospheric temperature in the pulverizer is 20 to -40 ° C, more preferably 10 to -30 ° C, still more preferably 0 to -25 ° C. This is preferable from the viewpoint of toner productivity. By setting the room temperature of the spiral chamber 212 in the pulverizer to 20 to -40 ° C, more preferably 10 to -30 ° C, and still more preferably 0 to -25 ° C, the toner surface changes due to heat, particularly on the toner surface. The release of magnetic iron oxide can be suppressed, and the pulverized raw material can be efficiently pulverized. When the atmospheric temperature in the pulverizer exceeds 0 ° C., it is not preferable from the viewpoint of toner productivity because the surface of the toner is deteriorated by heat during pulverization, in particular, the release of magnetic iron oxide existing on the toner surface and the fusion in the machine are liable to occur.
[0140]
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.
[0141]
The 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.
[0142]
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 320 of the mechanical pulverizer 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 deterioration of the toner due to heat can be suppressed, and the pulverized raw material can be efficiently pulverized. When ΔT between the temperature T1 (inlet temperature) and the temperature T2 (outlet temperature) of the mechanical pulverizer is smaller than 30 ° C., a so-called short pass may be caused in which particles are not sufficiently pulverized and discharged. From the viewpoint of toner performance. On the other hand, when the temperature is higher than 80 ° C., it may be excessively pulverized at the time of pulverization, and thus it is not preferable from the viewpoint of toner productivity because it easily causes magnetic iron oxide liberation and heat deterioration of the toner due to heat. .
[0143]
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 setting the inlet temperature of the mechanical pulverizer to 0 ° C. or lower and lower by 60 to 75 ° C. than Tg, toner surface deterioration due to heat 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 setting the outlet temperature of the mechanical pulverizer to be 5 to 30 ° C. lower than Tg, it is possible to suppress the toner surface deterioration due to heat and to efficiently pulverize the pulverized raw material.
[0144]
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. By setting the peripheral speed of the rotating rotor 314 to 80 to 180 m / s, more preferably 90 to 170 m / s, and still more preferably 100 to 160 m / s, the toner is insufficiently pulverized, excessively pulverized, and further magnetized due to excessive pulverization. The liberation of iron oxide 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 increases, and at the same time, the toner is excessively pulverized at the time of pulverization, and the toner surface is easily deteriorated and fused in the machine. That is not preferable.
[0145]
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 By setting the distance between the rotor 314 and the stator 310 to 0.5 to 10.0 mm, more preferably 1.0 to 5.0 mm, and still more preferably 1.0 to 3.0 mm, the toner is pulverized. It is possible to suppress toner surface alteration due to shortage or over-pulverization, and to efficiently pulverize the pulverized raw material. If 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 increases, and at the same time, it is excessively pulverized during the pulverization to release the magnetic iron oxide. Further, excessive grinding is not preferable from the viewpoint of toner productivity because the surface of the toner is easily changed by heat and the toner is easily fused in the machine.
[0146]
In addition, the pulverizer used in the present invention can obtain a toner having good developability, transferability and chargeability by controlling the surface roughness of the pulverization surfaces of the rotor and the stator to an appropriate state. . 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. This is not preferable from the viewpoint of toner productivity because it is sometimes excessively pulverized and easily causes surface modification of the toner due to heat, particularly liberation of magnetic iron oxide present on the toner surface and in-machine fusion.
[0147]
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) The measurement point was randomly shifted and measured several times, and the average value was obtained. At this time, the measurement was 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.
[0148]
Among the analysis parameters of the surface roughness, the centerline roughness Ra is a portion of the reference length L in the direction of the centerline from the roughness curve, and the centerline of the extracted portion is taken as the X axis and the vertical magnification. Is determined by the following equation when the roughness curve is expressed by Z = f (x).
[0149]
[Outside 12]

[0150]
Further, the maximum roughness Ry is determined by extracting a reference length from the roughness curve in the direction of the average line, and measuring the distance between the peak and valley bottom of the extracted portion in the direction of the vertical magnification of the roughness curve. To do. The 10-point average roughness Rz is 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. And the average of the absolute values of the bottom valley elevations from the lowest valley bottom to the fifth. In addition, a well-known method is used as a roughening process of the grinding | pulverization surface of the rotor and / or stator of this invention.
[0151]
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.
[0152]
That is, as a result of the study by the present inventors, the base material on the pulverized surface of the rotor and / or the stator is roughened as a pre-process, and the base material is anti-weared as a post-process, so that the toner can be easily obtained. The amount of magnetic iron oxide exposed on the particle surface can be controlled, and a toner capable of maintaining good developability can be obtained. In addition, the wear of the grinding surface of the rotor and stator can be reduced, and the toner can be ground stably over a long period of time. It turns out that it will be possible.
[0153]
A known method is used as the abrasion resistance treatment of the pulverized surface of the rotor and / or stator, and among these, treatments such as nitriding, plating, thermal spraying, and filling with a self-fluxing alloy are most preferable.
[0154]
The nitriding is a surface hardening treatment method for the purpose of improving the wear resistance and fatigue resistance of a work material. It is heated at an appropriate temperature for an appropriate time to diffuse nitrogen entirely or partially on the work material surface. The heat treatment for forming a nitride layer.
[0155]
Since the pulverization method of the present invention does not require the first classification step after the coarse pulverization step, the magnetic toner that should originally be sent to the second classification means is caused by electrostatic aggregation between particles caused by the fine particles. It is circulated again to the first classifying means, and as a result, it can be prevented from being excessively pulverized and becoming fine powder and ultrafine powder, so that the classification yield is improved. 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.
[0156]
Next, an airflow classifier that is preferably used as a classifying means constituting the toner manufacturing method of the present invention will be described.
[0157]
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.
[0158]
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 are also slid left and right. By the classification edges 17 and 18, the classification area 30 of the classification chamber 32 is divided into three.
[0159]
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. 2, the inlet pipes 14 and 15 are provided with a first gas introduction adjusting means 20 and a second gas introduction adjusting means 21 such as a damper, and static pressure gauges 28 and 29.
[0160]
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.
[0161]
In addition, on the downstream side of the air flow of the classification chamber 32, there are 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 communicate with each other like a pipe. Means are connected, and each may be provided with an opening / closing means such as a valve means.
[0162]
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.
[0163]
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.
[0164]
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.
[0165]
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 speed at which the powder is ejected from the raw material supply nozzle 16.
[0166]
In the toner production method and production system of the present invention, the toner having a sharp particle size distribution with a weight average particle size of 10 μm or less (particularly 8 μm or less) is obtained by controlling the pulverization and classification conditions. Can be generated efficiently.
[0167]
The dry toner of the present invention is characterized in that the surface of the toner particles is surface-treated by a surface treatment process in which the surface of the toner particles is passed through a surface treatment apparatus that applies a mechanical impact force. Therefore, a method preferably used as the toner surface treatment method constituting the toner production method of the present invention will be described with reference to FIGS.
[0168]
FIG. 10 is a schematic schematic configuration diagram showing the structure of the surface modifying apparatus system, and FIG. 11 is a schematic partial sectional view showing the structure of the processing unit 401 of the surface modifying apparatus I in the system of FIG. . 12 and 13 are a plan view and a cross-sectional view of the rotor attached to the surface modification device.
[0169]
This surface reforming device performs surface treatment of toner particles by pressing toner particles against the inside of the casing by centrifugal force with high-speed rotating blades and repeatedly applying thermomechanical impact force due to at least compression force and friction force. is there. As shown in FIG. 11, the processing unit 401 is provided with four rotating rotors 402a, 402b, 402c, and 402d in the vertical direction. The rotary rotors 402a to 402d are rotated by rotating the rotary drive shaft 403 by the electric motor 434 so that the peripheral speed of the outermost edge portion is, for example, 30 to 60 m / s. Further, the suction blower 424 (see FIG. 10) is operated to suck an air volume equal to or greater than the air flow rate generated by the rotation of the blades 409a to 409d provided integrally with the rotary rotors 402a to 402d. . Toner particles are sucked into the hopper 432 together with air from the feeder 415, and the introduced toner particles are introduced into the central portion of the first cylindrical processing chamber 89a through the powder supply pipe 431 and the powder supply port 430. The The toner particles are subjected to a surface treatment by the blade 409a and the side wall 407 in the first cylindrical treatment chamber 429a, and then the toner particles subjected to the surface treatment are a first powder provided in the central portion of the guide plate 408a. It passes through the discharge port 410a and is introduced into the center of the second cylindrical processing chamber 429b, and is further subjected to spheroidization processing by the blade 409b and the side wall 407.
[0170]
The toner particles surface-treated in the second cylindrical processing chamber 429b pass through the second powder discharge port 410b provided in the central portion of the guide plate 408b and enter the central portion of the third cylindrical processing chamber 429c. Introduced and further subjected to surface treatment by the blade 409c and the side wall 407, and further passed through the third powder discharge port 410c provided in the central portion of the guide plate 408c to the central portion of the fourth cylindrical processing chamber 429d. The toner particles are introduced and subjected to surface treatment by the blade 409d and the side wall 407. The air carrying the toner particles passes through the first to fourth cylindrical processing chambers 429a to 429d, passes through the discharge pipe 417, the cyclone 420, the bag filter 422, and the suction blower 424, and is out of the system. To be discharged.
[0171]
The toner particles introduced into the cylindrical processing chambers 429a to 429d are instantaneously subjected to mechanical hitting action by the blades 409a to 409d, and further collide with the side wall 407 to receive mechanical impact force. Due to the rotation of the blades 409a to 409d of a predetermined size respectively installed in the rotary rotors 402a to 402d, convection circulating from the central part to the outer periphery and from the outer periphery to the central part is generated in the space above the rotary rotor surface. The toner particles stay in the cylindrical processing chambers 429a to 429d and undergo a surface treatment. The surface of the toner particles is treated by heat generated by the mechanical impact force.
[0172]
As a specific method, each rotor is rotated at 30 to 60 m / s, and as shown in FIG. 10, a cyclone 420 and a blower 424 are attached to the outlet side of the surface reforming apparatus I, and a blower air volume is set to 2 to 4 m. ³ The toner is supplied from the inlet 432 at the top of the processing apparatus at a rate of 10 to 30 kg per hour by the auto feeder 415 while being sucked at / min. In the surface treatment step, the toner particles are allowed to stay in an air stream having a temperature lower by 5 ° C. or more than the glass transition temperature Tg of the binder resin [that is, air current temperature T ≦ (Tg−5 ° C. of binder resin)]. It is preferable to obtain a surface-treated toner obtained by continuously applying a mechanical impact force to the toner particles so as to pass through the surface treatment apparatus. Further, in the surface treatment step, the toner particles are dispersed in an air stream at a temperature that is 20 ° C. or more lower than the DSC endothermic main peak temperature of the wax [that is, air current temperature T ≦ (wax DSC endothermic main peak temperature−20 ° C.)] It is preferable to obtain a surface-treated toner obtained by continuously applying a mechanical impact force to the toner particles so as to pass through the surface treatment apparatus without being retained. On the other hand, when the toner particles are subjected to a surface treatment at a temperature of (binder resin Tg−5 ° C.) or higher or (wax peak temperature−20 ° C.) or higher, the frictional heat generated during the surface treatment is generated. Is accumulated, and the wax dispersed in the toner oozes out and re-aggregates on the toner surface.
[0173]
Thus, in the present invention, the mechanical pulverizer described above is combined with the surface treatment of the toner particle surface by passing through the surface treatment device that continuously applies the mechanical impact force. In a state where the heat generation of the toner particles caused by impact force and friction is effectively suppressed, it is possible to perform sufficient surface treatment of the toner particles at a low temperature and in a short time without accumulating heat. It becomes possible to easily control the exposure amount of magnetic iron oxide.
[0174]
The toner production method of the present invention can be preferably used for producing toner particles used for developing an electrostatic image. In order to produce the toner of the present invention, a mixture containing at least a binder resin and magnetic iron oxide is used as a material. In addition, a charge control agent, wax, and other additives are used as necessary. These materials are mixed thoroughly by a mixer such as a Henschel mixer or a ball mill, and then melted, kneaded and kneaded using a heat kneader such as a roll, kneader and extruder to mix and mix the resins with each other. In addition, a pigment or dye may be dispersed or dissolved as necessary, cooled and solidified, and then pulverized and classified to obtain a toner. For example, as a mixer, Henschel mixer (Mitsui Mining Co., Ltd.); Super mixer (Kawata Co., Ltd.); Ribocorn (Okawara Seisakusho Co., Ltd.); (Manufactured by Taiheiyo Kiko Co., Ltd.); Ladige mixer (manufactured by Matsubo Co., Ltd.), and kneaders: KRC kneader (manufactured by Kurimoto Iron Works Co.); bus co kneader (manufactured by Buss); (Manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikekai Iron Works Co., Ltd.); triple roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho Co., Ltd.); Mining company); MS pressure kneader, Nider Ruder (Moriyama Seisakusho); Banbury mixer (Kobe Steel) As a pulverizer, a counter jet mill, a micron jet, an inomizer (manufactured by Hosokawa Micron Co.); 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.); ULMAX (manufactured by Nisso Engineering Co., Ltd.); SK Jet O Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries Co., Ltd.); turbo mill (manufactured by Turbo Kogyo Co., Ltd.). , Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron Corporation); Elbow Jet (Nittetsu Mining) ), Disper Separator separator (manufactured by Nippon Pneumatic Industrial Co., Ltd.); YM micro cut (manufactured by Yaskawa Shoji Co., Ltd.), and as a sieving device used for sieving coarse particles, Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Gyro shifter (Tokuju Kogakusha); Vibrasonic system (Dalton); Soniclean (Shinto Kogyo); Turbo screener (Turbo Kogyo); Micro shifter (Ogino Sangyo); Circular vibrating sieve Is mentioned.
[0175]
In this invention, it is preferable to use the apparatus system of the structure demonstrated above for a grinding | pulverization process and a classification process.
[0176]
The configuration of the image forming apparatus of the present invention will be described with reference to FIG.
[0177]
This image forming apparatus is a recording apparatus of a development and cleaning process (cleanerless system) using a transfer type electrophotographic process. It has a process cartridge from which a cleaning unit having a cleaning member such as a cleaning blade is removed, uses a magnetic one-component developer (magnetic toner) as a developer, and a developer layer on a developer carrier (toner carrier). 2 is an example of an image forming apparatus for non-contact development in which the image carrier and the image carrier are arranged in a non-contact manner.
[0178]
Reference numeral 501 denotes a rotating drum type OPC photosensitive member as an electrostatic charge image holding member, which is driven to rotate clockwise (in the direction of the arrow). Reference numeral 502 denotes a charging roller as a contact charging member. The charging roller 502 is disposed in pressure contact with the photoreceptor 501 with a predetermined pressing force. n is a charging nip portion which is a nip portion between the photosensitive member 501 and the charging roller 502. In this embodiment, the charging roller 502 is rotationally driven in the counter direction (the direction opposite to the moving direction of the photosensitive member surface) at the charging nip n which is a contact surface with the photosensitive member 501. In addition, the conductive fine powder is supported on the surface of the charging roller 502 so that the coating amount is uniform in one layer.
[0179]
A DC voltage of −700 V is applied as a charging bias to the cored bar 502a of the charging roller 502 from the charging bias application power source S1. In this embodiment, the surface of the photoreceptor 501 is uniformly charged by a direct injection charging method to a potential (−680 V) substantially equal to the voltage applied to the charging roller 502.
[0180]
A laser beam scanner (exposure device) 503 includes a laser diode, a polygon mirror, and the like. This laser beam scanner outputs intensity-modulated laser light (wavelength 740 nm) corresponding to the time-series electric digital pixel signal of the target image information, and scans and exposes the uniformly charged surface of the photoreceptor 501 with the laser light L. To do. By this scanning exposure, an electrostatic latent image corresponding to target image information is formed on the photoreceptor 501.
[0181]
Reference numeral 504 denotes a developing device. The electrostatic latent image on the surface of the photoreceptor 501 is developed as a toner image by the developing device. The developing device 504 of this embodiment is a non-contact type reversal developing device using a negatively chargeable magnetic one-component insulating developer (magnetic toner) as a developer. The developer 504d contains toner particles (t) and conductive fine powder (m).
[0182]
Reference numeral 504a denotes a non-magnetic developing sleeve having a diameter of 16 mm that includes a magnet roll 504b as a developer carrying member. The developing sleeve 504a is disposed to face the photosensitive member 501 with a separation distance of 320 μm, and the developing portion (developing region portion) a which is the facing portion with respect to the photosensitive member 501 determines the rotation direction of the photosensitive member 501. The photoconductor 501 is rotated at a peripheral speed of 120% in the forward direction.
[0183]
On the developing sleeve 504a, a developer 504d is coated in a thin layer by an elastic blade 504c. The developer 504d is given a charge while the layer thickness on the developing sleeve 504a is regulated by the elastic blade 504c.
[0184]
The developer 504d coated on the developing sleeve 504a is conveyed to the developing unit a, which is a portion opposite to the photosensitive member 501 and the developing sleeve 504a, as the developing sleeve 504a rotates.
[0185]
A developing bias voltage is applied to the developing sleeve 504a 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 × 10 ⁶ One-component jumping development is performed between the developing sleeve 504a and the photosensitive member 501 using a superposed voltage of a rectangular alternating voltage of V / m).
[0186]
Reference numeral 505 denotes a medium resistance transfer roller as a contact transfer unit, and 0.16 × 10 6 is provided on the photoreceptor 501. ^-2 ~ 24.5 × 10 ^-2 A transfer nip b is formed by applying a contact pressure of MPa. A transfer material P as a recording medium is fed to the transfer nip b from a paper feed unit (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 505 from a transfer bias application power source S3. Thus, the toner image on the photosensitive member 501 side is sequentially transferred onto the surface of the transfer material P fed to the transfer nip portion b.
[0187]
In this embodiment, the transfer roller 505 has a resistance of 5 × 10. ⁸ Transferring was performed by applying a DC voltage of +2000 V using a Ωcm one. That is, the transfer material P introduced into the transfer nip portion b is nipped and conveyed through the transfer nip portion b, and the toner images formed and supported on the surface of the photosensitive member 501 are sequentially transferred to the surface side of the transfer material P by electrostatic force and pressing force. Will be transcribed.
[0188]
Reference numeral 506 denotes a fixing device such as a thermal fixing method. The transfer material P that has been fed to the transfer nip b and onto which the toner image has been transferred is separated from the surface of the photoreceptor 501 and introduced into the fixing device 506, where the toner image is fixed and an image formed product (print, As a copy).
[0189]
In the image forming apparatus of this example, the cleaning unit is removed, and the residual transfer developer (transfer residual toner) tr remaining on the surface of the photoreceptor 501 after the transfer of the toner image onto the transfer material P is removed by the cleaning unit. Instead, as the photosensitive member 501 rotates, it reaches the developing section a via the charging section n and is cleaned (collected) by the developing device 504.
[0190]
In the printer of this example, the three process devices of the photosensitive member 501, the charging roller 502, and the developing device 504 are configured as a process cartridge that is detachable from the printer body. The combination of process devices to be processed into a process cartridge is not limited to the above, and may have a cleaning step and is arbitrary.
[0191]
An appropriate amount of the conductive fine powder m mixed in the developer 504d of the developing device 504 is transferred to the photoconductor 501 side together with the toner particles t when the electrostatic latent image on the photoconductor 501 is developed by the developing device 504.
[0192]
The toner image on the photoreceptor 501, that is, the toner particles t, is attracted to the transfer material P, which is a recording medium, and actively transfers at the transfer portion b due to the influence of the transfer bias. However, since the conductive fine powder m on the photoconductor 501 is conductive, it does not actively transfer to the transfer material P side, and remains substantially adhered and held on the photoconductor 501.
[0193]
In this example, since the image forming apparatus does not have a cleaning process, the transfer residual toner particles t and the conductive fine powder m remaining on the surface of the photoconductor 501 after transfer are exposed to light as the photoconductor 501 rotates. It is carried to the charging unit n that is the nip portion of the charging roller 502 that is the contact charging member and the body 501, and adheres to or mixes with the charging roller 502. Accordingly, direct charging of the photosensitive member 501 is performed in a state where the conductive fine powder m exists in the nip portion n between the photosensitive member 501 and the charging roller 502.
[0194]
Due to the presence of the conductive fine powder m, even when the transfer residual toner particles t adhere to or mix in the charging roller 502, the contact property and contact resistance of the charging roller 502 to the photosensitive member 501 can be maintained. Direct injection charging of the photoreceptor 501 by the roller 502 can be performed.
[0195]
That is, the charging roller 502 comes into close contact with the photoreceptor 501 through the conductive fine powder m, and the conductive fine powder m rubs the surface of the photoreceptor 501. As a result, the charging of the photosensitive member 501 by the charging roller 502 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 approximately equal to the voltage applied to the charging roller 502 can be applied to the photoconductor 501.
[0196]
Further, the transfer residual toner particles t adhering to or mixed in the charging roller 502 are gradually discharged from the charging roller 502 onto the photosensitive member 501 and reach the developing unit a along with the movement of the surface of the photosensitive member 501. Cleaning (collection) is performed in the apparatus 504.
[0197]
In the development and cleaning, the toner particles remaining on the photosensitive member 501 after the transfer are developed at the next and subsequent developments in the image forming process (after development, the latent image is developed again through the charging process and the exposure process). This is recovered by the fog removal bias of the developing device (fogging removal potential difference Vback which is a potential difference between the DC voltage applied to the developing device and the surface potential of the photoreceptor). In the case of reversal development, as in the image forming apparatus in this embodiment, this development and cleaning includes an electric field for collecting toner particles from the dark portion potential of the photosensitive member due to the developing bias to the developing sleeve, and a bright portion of the photosensitive member from the developing sleeve. This is done by the action of an electric field that causes toner particles to adhere to (develop) the potential. Further, when the image forming apparatus is operated, the conductive fine powder m contained in the developer of the developing device 504 moves to the surface of the photoconductor 501 at the developing unit a, and moves along with the movement of the surface of the photoconductor 501. Since the conductive fine powder m is continuously supplied to the charging portion n by being carried to the charging portion n through the transfer portion b, the conductive fine powder m is decreased in the charging portion n due to dropping, Even if the conductive fine powder m of the charging portion n is deteriorated, a decrease in charging property is prevented, and good charging property of the photoreceptor 501 is stably maintained.
[0198]
Thus, in an image forming apparatus using a contact charging system, a transfer system, or a toner recycling process, a simple charging roller 502 is used as a contact charging member, and uniform chargeability is imparted to the photoconductor 501 as an image carrier at a low applied voltage. be able to. In addition, although the charging roller 502 is contaminated with the transfer residual toner particles t, the ozone-less direct injection charging can be stably maintained over a long period of time, and uniform chargeability can be provided. Therefore, it is possible to obtain an image forming apparatus with a simple configuration and low cost, which is free from troubles caused by ozone products, troubles caused by defective charging, and the like.
[0199]
Further, instead of the image forming apparatus shown in FIG. 14, an image forming apparatus using the intermediate transfer member shown in FIG. 15 can be used. FIG. 15 shows an image forming apparatus of a type in which a toner image on an electrostatic charge image holding member is transferred onto an intermediate transfer member and then a toner image on the intermediate transfer member is secondarily transferred onto a recording material. It is a preferable image forming apparatus for a toner having high transferability and stable charge, such as toner.
[0200]
The electrostatic charge image holding member 601 has a photosensitive layer 601b having an organic optical semiconductor on a substrate 601a, and is a charging roller 602 (conductive elastic layer 602a, cored bar 602b) that rotates in the direction of an arrow and rotates oppositely. To charge the photosensitive member 601 to a surface potential of about -600V. The exposure 603 is turned on and off on the photosensitive member by a polygon mirror in accordance with digital image information, thereby forming an electrostatic charge image having an exposure portion potential of −100V and a dark portion potential of −600V. Using a plurality of developing units 604-1, 604-2, 604-3, and 604-4, a toner image was obtained by using a reversal developing method on magenta toner, cyan toner, yellow toner, or black toner on the photoreceptor 601. The toner image is transferred onto the intermediate transfer member 605 (elastic layer 605a, cored bar 605b as a support) for each color, and a four-color overlaid developed image is formed on the intermediate transfer member 605. The transfer residual toner on the photoconductor 601 is collected in a residual toner container 609 by a cleaner member 608.
[0201]
Since the toner according to the present invention has high transfer efficiency, problems are unlikely to occur even in a system without a simple bias roller or cleaner member.
[0202]
The intermediate transfer member 605 was coated with an elastic layer 605a in which a carbon black conductive member was sufficiently dispersed in nitrile-butadiene rubber (NBR) on a pipe-shaped cored bar 605b. The hardness of the coat layer is 30 degrees according to JIS K-6301, and the volume resistivity is 10 ⁹ It was Ω · cm. The transfer current required for transfer from the photosensitive member 601 to the intermediate transfer member 605 is about 5 μA, which was obtained by applying +2000 V to the cored bar 605b from a power source. The surface of the intermediate transfer member may be cleaned with the cleaner member 610 after the toner image is transferred from the intermediate transfer member 605 to the transfer material 606. After the transfer process, the toner image on the transfer material is fixed by a fixing device 611.
[0203]
The transfer roller 607 was produced by coating a 20 mm cored bar 607b with a carbon electroconductivity imparting member sufficiently dispersed in an ethylene-propylene-diene terpolymer (EPDM) foam. The volume resistivity of the elastic layer 607a is 10 ⁶ What used the value whose hardness of 35 degree | times on the basis of JISK-6301 by ohm * cm was used. A voltage was applied to the transfer roller to pass a transfer current of 15 μA.
[0204]
【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.
[0205]
Table 1 shows resins used in Examples, Table 2 shows waxes, and Table 3 shows magnetic iron oxide particles. Styrenic resins (binder resins A, B, and D) were synthesized by a solution polymerization method, and polyester resin (binder resin C) was synthesized by a dehydration condensation method. The manufacturing method of the magnetic material is as follows.
[0206]
Production example 1 of magnetic iron oxide particles
In the ferrous sulfate solution, Fe ²⁺ After mixing with 0.95 equivalent of sodium hydroxide aqueous solution, Fe (OH) ₂ A 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) ₂ Magnetic 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 and filtered and dried by a conventional method. Since the primary particles of the obtained magnetic iron oxide particles are aggregated to form aggregates, a compressive force and a shear force are applied to the aggregates of magnetic iron oxide particles using a mix muller. The aggregate was crushed to make the magnetic iron oxide particles primary particles, and the surface of the magnetic iron oxide particles was smoothed to obtain magnetic iron oxide particles 1 having the characteristics shown in Table 3. The average particle diameter of the magnetic iron oxide particles was 0.21 μm.
・ 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.
Production example 3 of magnetic iron oxide particles
Similar to Production Example 1, magnetic iron oxide particles 3 of Production Example 3 were obtained by changing the amount of silicon element.
Production example 4 of magnetic iron oxide particles
Similar to Production Example 1, magnetic iron oxide particles 4 of Production Example 4 were obtained by changing the amount of silicon element.
Magnetic iron oxide particle production example 5
Similar to Production Example 1, magnetic iron oxide particles 5 of Production Example 5 were obtained by changing the amount of silicon element.
[0207]
[Table 1]

[0208]
[Table 2]

[0209]
[Table 3]

[0210]

The above materials were premixed with a Henschel mixer and then melt-kneaded with a twin-screw kneading extruder set at 130 ° C.
[0211]
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 6.8 μm. Toner particles were obtained. The obtained toner particles were subjected to a surface treatment by a surface treatment process for continuously passing a mechanical impact force as shown in FIG. 10 to obtain a toner particle of this example.
[0212]
In this embodiment, the grinding surface of the rotor 314 and the stator 310 of the mechanical crusher 301 has a center line roughness Ra of 5.9 μm, a maximum roughness Ry of 32.4 μm, and a ten-point average roughness of 21.4 μm. Then, the surface was roughened so that the wear resistance was improved by nitriding. 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. As a specific method of surface treatment, each rotor is rotated at a peripheral speed of 40 m / s, and the blower air volume is 3.0 m. ² In this state, the toner was supplied to the auto feeder at a rate of 20 kg / hour and operated for 1 hour for surface treatment. At this time, the passing time of the toner in the processing apparatus was about 20 seconds. At this time, the temperature at the exhaust outlet of the apparatus was 49 ° C.
[0213]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. obtained by mixing 1.2 parts by weight, 1.0 part by weight of strontium titanate, and 2.0 parts by weight of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. . 1 was prepared.
[0214]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of No. 1 and the average particle diameter is shown in FIG. FIG. 17 (graph 2) shows the UV spectrum indicating the surface magnetic substance exposure amount of No. 1, and Table 4 shows the data of the circularity frequency of the measurement result of the toner using the FPIA 2100.
[0215]
[Table 4]

[0216]
This toner No. As an image forming apparatus, a cleaning unit is removed from a commercially available LBP printer (LBP-250, manufactured by Canon Inc.), and the apparatus is converted into an image forming apparatus of a cleanerless system as shown in FIG. 5 while replenishing toner in a low temperature and low humidity environment (15 ° C., 10% RH), a normal temperature and normal humidity environment (23.5 ° C., 60% RH), and a high temperature high humidity environment (30 ° C., 80% RH). A 1,000-sheet print test was performed to evaluate image density, fogging, image quality, and toner adhesion to the charging member. Also, take out the LBP950 fixing device that uses a heat roll fixing device, operate it outside the printer, set the fixing roller temperature arbitrarily, and modify the external fixing so that the process speed is 235 mm / s The fixability and offset resistance were evaluated using a container. Further, the transfer efficiency and pattern recovery failure were evaluated using a commercially available LBP950. The evaluation results are shown in Tables 6-9.
[0217]
Fixability
The fixing property is 0.49 × 10 by passing a solid black image through a fixing device adjusted to 150 ° C. ^-2 The fixed image was rubbed and reciprocated five times with Silbon paper under a load of MPa, and the reduction rate (%) of the image density before and after rubbing was evaluated.
A: Less than 10%
B: 10% or more and less than 20%
C: 20% or more
[0218]
Offset resistance
The offset resistance was evaluated based on the degree of contamination on an image after 3000 sheets of a sample image having an image area ratio of about 5%.
A: Dirt is not seen.
B: Slightly dirty.
C: Dirt that affects the image is generated.
[0219]
Evaluation of image density, fogging and image quality
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. The image quality is evaluated by forming an image with 100 isolated dots and representing how many dots out of 100 can be represented. The higher the number of dots reproduced, the higher the image quality.
[0220]
These evaluations were performed at the initial timing of 5000 sheets and at the respective timings after being left outside the machine for a day.
[0221]
Toner adhesion to charging member
In addition, after a print test of 5,000 sheets in a low temperature and low humidity environment, the degree of toner adhesion to the charging member was evaluated.
A: Adhesion is not seen.
B: Slight adhesion is observed.
C: Adhered to such an extent that it appears as unevenness on the halftone image.
[0222]
Transfer efficiency
Regarding the evaluation of the transfer efficiency, the transferability variation at the initial stage and after the endurance of 10,000 sheets was evaluated in a normal temperature and humidity environment with a commercially available LBP printer (LBP-950, manufactured by Canon Inc.). 75g / cm for transfer paper ² Plain 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.
[0223]
Pattern collection failure
Regarding pattern recovery failure, print out halftone images (repeated horizontal lines of 2 dots and 3 spaces) after printing out the same vertical pattern (repeated vertical lines of 2 dots and 98 spaces) in a low temperature and low humidity environment. A test was conducted to visually evaluate whether or not a halftone image corresponding to a vertical line pattern was generated.
A: No shading is seen.
B: Slight unevenness is seen.
C: Uneven shading appears remarkably on the halftone image.
[0224]
<Example 2>
In the same manner as in Example 1, the toner No. 2 was produced. However, the rotor 314 was ground at a peripheral speed of 125 m / s. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 37 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 55 degreeC.
[0225]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) is mixed with 1.2 parts by mass, 0.8 parts by mass of strontium titanate, and further mixed with 2.0 parts by mass of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. No. 2 was prepared.
[0226]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 2 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0227]
<Example 3>
In the same manner as in Example 1, the toner No. 3 was produced. However, the rotor 314 was ground at a peripheral speed of 114 m / s. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 45 ° C. The exhaust outlet airflow temperature of the apparatus during the surface treatment was 53 ° C.
[0228]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. obtained by mixing 2.0 parts by mass of 1.0 part by mass, 2.0 parts by mass of strontium titanate, and zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. . 3 was prepared.
[0229]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 3 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0230]
<Example 4>
In the same manner as in Example 1, the toner No. 4 was produced. However, the rotor 314 was ground at a peripheral speed of 150 m / s. At this time, the inlet temperature T1 was −10 ° C. and the outlet temperature T2 was 63 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 72 degreeC.
[0231]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. by mixing 2.0 parts by mass of 1.2 parts by mass, 0.8 parts by mass of strontium titanate, and zinc oxide fine powder having a resistance of 100 Ω · cm containing aluminum as conductive fine powder. . 4 was prepared.
[0232]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the degree of circularity 4 and the average particle size is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0233]
<Example 5>
In the same manner as in Example 1, the toner No. 5 was produced. However, the rotor 314 was ground at a peripheral speed of 90 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 30 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 35 degreeC.
[0234]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. by mixing 2.0 parts by mass of 1.2 parts by mass, 2.4 parts by mass of strontium titanate, and zinc oxide fine powder having a resistance of 100 Ω · cm containing aluminum element as conductive fine powder. . 5 was prepared.
[0235]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 5 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0236]
<Example 6>
In the same manner as in Example 1, the toner No. 6 was produced. However, the rotor 314 was ground at a peripheral speed of 115 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 40 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 40 degreeC.
[0237]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. by mixing 2.0 parts by mass of 1.0 part by mass, 2.4 parts by mass of strontium titanate, and zinc oxide fine powder having a resistance of 100 Ω · cm containing aluminum element as conductive fine powder. . 6 was prepared.
[0238]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 6 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0239]
<Example 7>
In the same manner as in Example 1, the toner No. 7 was produced. However, the rotor 314 was ground at a peripheral speed of 130 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 45 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 37 degreeC.
[0240]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) 1.0 part by mass of tin oxide fine powder having a resistance of 130 Ω · cm and 1.0 part by mass as conductive fine powder were mixed with 1.0 part by mass of strontium titanate and 1.0 part by mass. 7 was prepared.
[0241]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 7 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0242]
<Example 8>
In the same manner as in Example 1, the toner No. 8 was produced. However, the rotor 314 was ground at a peripheral speed of 125 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 42 ° C. Moreover, the exhaust outlet airflow temperature of the apparatus at the time of surface treatment was 40 degreeC.
[0243]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) 1.0 part by mass, 0.6 part by mass of strontium titanate, and 1.0 part by mass of a tin oxide fine powder having a resistance of 130 Ω · cm as a conductive fine powder were mixed. 8 was prepared.
[0244]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. FIG. 16 (graph 1) shows the relationship between the circularity of 8 and the average particle diameter. Moreover, the result of having done the same test is shown to Tables 6-9.
[0245]
<Comparative Example 1>
In the formulation shown in Table 5, the toner No. 11 was produced. The pulverization process is performed using a collision-type airflow pulverizer as shown in FIG. 8, the obtained pulverized product is first classified, and the finely pulverized powder is second classified using a multi-division classifier utilizing the Coanda effect. The surface treatment process was not performed. Hydrophobic silica fine powder hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone with respect to 100 parts by mass of the toner particles (80% methanol wettability, 120 m BET specific surface area) ² / G) Toner No. by mixing 2.0 parts by mass of 1.2 parts by mass, 0.4 parts by mass of strontium titanate, and zinc oxide fine powder having a resistance of 100 Ω · cm containing aluminum element as conductive fine powder. . 11 was prepared. The physical properties of the toner thus obtained are shown in Table 5. The relationship between the circularity of 11 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0246]
<Comparative example 2>
In the formulation shown in Table 5, the toner No. 12 was produced. The pulverization process is pulverized with a fine pulverizer using collision airflow pulverization, and the finely pulverized powder obtained is classified using a multi-division classifier utilizing the Coanda effect, and the airflow temperature at the exhaust outlet of the apparatus during surface treatment Was 45 ° C. Hydrophobic silica fine powder hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone with respect to 100 parts by mass of the toner particles (80% methanol wettability, 120 m BET specific surface area) ² / G) Toner No. obtained by mixing 1.2 parts by mass, 2.0 parts by mass of strontium titanate, and 2.0 parts by mass of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. . 12 was prepared. The physical properties of the toner thus obtained are shown in Table 5. The relationship between the circularity of 12 and the average particle size is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0247]
<Comparative Example 3>
In the same manner as in Example 1, the toner No. 13 was produced. However, the rotor 314 was ground at a peripheral speed of 120 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 42 ° C. Moreover, the surface treatment after classification was not performed.
[0248]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. obtained by mixing 1.2 parts by weight, 1.0 part by weight of strontium titanate, and 2.0 parts by weight of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. . 13 was prepared.
[0249]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 13 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0250]
<Comparative example 4>
In the same manner as in Example 1, the toner No. 14 was produced. However, the rotor 314 was ground at a peripheral speed of 145 m / s. At this time, the inlet temperature T1 was −10 ° C., and the outlet temperature T2 was 60 ° C. In addition, the toner particles obtained after the classification were used to instantaneously pass through 300 ° C. hot air.
[0251]
Hydrophobic silica fine powder hydrophobized with 15% by weight of hexamethyldisilazane and 15% by weight of dimethyl silicone (100% methanol wettability, 120 m BET specific surface area) with respect to 100 parts by weight of the obtained toner particles. ² / G) Toner No. obtained by mixing 1.2 parts by weight, 1.0 part by weight of strontium titanate, and 2.0 parts by weight of zinc oxide fine powder containing aluminum element and having a resistance of 100 Ω · cm as conductive fine powder. . 14 was prepared.
[0252]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 14 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having done the same test is shown to Tables 6-9.
[0253]
<Example 9>
Using the toner particles produced in Example 4, 100 parts by mass of the toner particles were subjected to hydrophobic treatment with 15% by mass of hexamethyldisilazane and 15% by mass of dimethylsilicone (hydrophobic silica fine powder (methanol wettability 80%, BET specific surface area 120m ² / G) 1.2 parts by mass and 0.8 parts by mass of strontium titanate were mixed to prepare toner No. 9 was prepared.
[0254]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 9 and the average particle diameter is shown in FIG. 16 (Graph 1).
[0255]
This toner No. Using a commercially available LBP printer (LBP-2160, manufactured by Canon Inc.) 9, a print test of 10,000 sheets was performed in a low temperature and low humidity environment, a normal temperature and normal humidity environment, and a high temperature and high humidity environment. In addition, the LBP950 fixing device that uses the heat roll fixing device is taken out, operates outside the printer, the fixing roller temperature can be arbitrarily set, and the external fixing is modified so that the process speed is 235 mm / s. The fixability and offset resistance were evaluated using a container. The evaluation results are shown in Tables 10-13.
[0256]
Fixability
The fixing property is 0.49 × 10 by passing a solid black image through a fixing device adjusted to 150 ° C. ^-2 The fixed image was rubbed and reciprocated five times with Silbon paper under a load of MPa, and the reduction rate (%) of the image density before and after rubbing was evaluated.
A: Less than 10%
B: 10% or more and less than 20%
C: 20% or more
[0257]
Offset resistance
The offset resistance was evaluated based on the degree of contamination on an image after 3000 sheets of a sample image having an image area ratio of about 5%.
A: Dirt is not seen.
B: Slightly dirty.
C: Dirt that affects the image is generated.
[0258]
Evaluation of image density, fog, and image quality
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. The image quality is evaluated by forming an image of 100 isolated dots and representing how many dots out of 100 can be represented. The higher the number of dots reproduced, the higher the image quality.
[0259]
These evaluations were performed at the initial timing of 10,000 sheets and at the respective timings after being left outside the apparatus for a day.
[0260]
Transferability evaluation
Using a commercially available LBP printer (LBP-2160, manufactured by Canon Inc.), the transfer bias is shaken at 2 μA intervals between 2 to 20 μA (ie 2, 4, 6, 8, 10, 12, 14, 16). , 18, 20 μm), 90 g / m ² 5 mm squares (development amount 0.8 mg / cm) at two positions 30 mm from the top and 30 mm from the left and right ends and a total of three positions 30 mm from the top and the center position ² ) Was printed using each toner, and then transferred, and evaluated within a range where a transfer rate of 90% or more was obtained.
[0261]
The transfer rate was determined as follows.
[0262]
The above chart image is transferred onto a transfer paper, and a tape is pasted on the obtained image. On the other hand, the image remaining on the drum is peeled off with the tape, and the image is pasted on the transfer paper. Measure with a Macbeth densitometer. D is the average density of the three locations on the transfer paper. ₁ , D is the average density of the three remaining images on the drum. ₂ , The value obtained from the following formula is the transfer rate.
[0263]
Transfer rate (%) = D ₁ / (D ₁ + D ₂ )
A: A region having a transfer rate of 90% or more exists in a range of 7 points or more in a region of 2 to 20 μA.
B: A region having a transfer rate of 90% or more exists in a range of 5 to 6 points in a region of 2 to 20 μA.
C: A region having a transfer rate of 90% or more exists in a range of 2 to 4 points in a region of 2 to 20 μA.
D: Only 1 point or less of a region with a transfer rate of 90% or more exists in a region of 2 to 20 μA.
[0264]
Photoconductor contamination and cleaning performance evaluation
Using Canon's LBP-2160, a constant amount of toner with a toner consumption of 2.5 g / A4 1000 sheets of paper is continuously transferred from the developing device to the photoconductor, and the photosensitive when rotating idly for 20,000 sheets continuously. Body contamination and cleanability were evaluated every 1000 sheets. Photoconductor contamination was visually observed on the surface of the photoconductor, and the occurrence of contamination was confirmed with the toner fused to the surface of the photoconductor. Regarding the poor cleaning, the surface of the photoconductor was visually observed, and the occurrence of a cleaning failure was confirmed by streaks on the surface of the photoconductor. The toner consumption amount of 1000 sheets of 2.5 g / A4 paper is extremely small compared to the consumption amount in normal image formation, and is the amount of residual toner when a solid image is printed out with a transfer efficiency of 95%. Equivalent to.
A: No occurrence at 20,000 sheets.
B: Generated at 1.5 to 20,000 sheets.
C: Generated at 1 to 15,000 sheets.
D: Occurs below 10,000 sheets.
[0265]
<Example 10>
Using the toner particles produced in Example 5, 100 parts by mass of the toner particles were subjected to a hydrophobic silica fine powder hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone (methanol wettability 80%, BET specific surface area 120m ² / G) 1.2 parts by mass and 2.4 parts by mass of strontium titanate were mixed to prepare toner No. 10 was prepared.
[0266]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 10 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having tested similarly is shown to Tables 10-13.
[0267]
<Comparative Example 5>
Using the toner particles produced in Comparative Example 1, a hydrophobic silica fine powder hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone with respect to 100 parts by mass of the toner particles (80% methanol wettability, BET specific surface area 120m ² / G) 1.2 parts by mass and 0.4 parts by mass of strontium titanate were mixed to prepare toner No. 15 was prepared.
[0268]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. The relationship between the circularity of 15 and the average particle diameter is shown in FIG. 16 (Graph 1). Moreover, the result of having tested similarly is shown to Tables 10-13.
[0269]
<Comparative Example 6>
Hydrophobic silica fine powder (methanol wettability 80%, hydrophobized with 15% by mass of hexamethyldisilazane and 15% by mass of dimethyl silicone is used for 100 parts by mass of the toner particles produced in Comparative Example 4. BET specific surface area 120m ² / G) Toner No. 1 was mixed with 1.2 parts by mass and 1.0 part by mass of strontium titanate. 16 was prepared.
[0270]
The toner internal formulation, pulverization conditions, surface treatment conditions and physical property values are shown in Table 5. FIG. 16 (graph 1) shows the relationship between the circularity of 16 and the average particle diameter. Moreover, the result of having tested similarly is shown to Tables 10-13.
[0271]
[Table 5]

[0272]
[Table 6]

[0273]
[Table 7]

[0274]
[Table 8]

[0275]
[Table 9]

[0276]
[Table 10]

[0277]
[Table 11]

[0278]
[Table 12]

[0279]
[Table 13]

[0280]
【The invention's effect】
According to the present invention, a toner having a specific magnetic iron oxide on the toner surface, having a specific circularity and generating less waste toner, can achieve a toner with high transfer efficiency, and can be used under high and low humidity. Even in this case, high image quality can be stably obtained, image defects do not occur over time, and transfer efficiency can be improved without impairing fixability.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining 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 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 the line DD ′ in FIG. 3. FIG.
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 schematic sectional view of a conventional collision-type airflow crusher.
FIG. 9 is a schematic cross-sectional view of a multi-divided airflow classifier used for conventional second classifying means.
FIG. 10 is a schematic overview of an apparatus system showing an example of a surface treatment apparatus used in the present invention.
FIG. 11 is a schematic cross-sectional view of a surface treatment apparatus used in the present invention.
FIG. 12 is a schematic plan view of a rotating rotor portion of the surface treatment apparatus used in the present invention.
FIG. 13 is a schematic cross-sectional view of a rotating rotor portion of the surface treatment apparatus used in the present invention.
FIG. 14 is a schematic view showing an example of an image forming apparatus suitable for forming an image using the magnetic toner of the present invention.
FIG. 15 is a schematic view showing an example of an image forming apparatus suitable for forming an image using the magnetic toner of the present invention.
FIG. 16 is a diagram showing a relationship (graph 1) between particle size and circularity.
FIG. 17 is a graph showing an absorption spectrum (graph 2) of magnetic iron oxide extracted from the surface of toner particles.

Claims (14)

In a toner having toner particles containing at least a binder resin and magnetic iron oxide,
When the toner has a weight average particle diameter of 4 to 12 μm and the toner has a particle diameter of 3 μm or more, the following formula (1)
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 is a particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter of is shown. ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value of particles having a circularity of 0.950 or more Y ≧ exp5.31 × X ^−0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
A dry toner characterized by having an absorbance at a wavelength of 340 nm of 1.0 to 2.5 in a solution obtained by extracting 20 mg of the toner with 5 ml of 3 mol / l hydrochloric acid for 50 minutes. 2. The dry toner according to claim 1, wherein an absorbance at a wavelength of 340 nm is 1.3 to 2.3 in a solution obtained by extracting 20 mg of the toner with 5 ml of 3 mol / l hydrochloric acid for 50 minutes. 3. The dry toner according to claim 1, wherein the magnetic iron oxide is contained in an amount of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin. A mixture having at least a binder resin and magnetic iron oxide is melt-kneaded, and the obtained kneaded product is cooled. A toner manufacturing method for obtaining toner particles, and further producing a toner through a surface treatment step of surface-treating the toner particles,
The crushing means includes a rotor that is a rotating body attached to at least a central rotating shaft, and a stator that is arranged around the rotor while maintaining a certain distance from the surface of the rotor. Is a mechanical crusher that performs crushing while holding
The surface treatment step is a step of performing surface treatment by passing toner particles through a surface treatment apparatus that continuously applies mechanical impact force.
In the toner having a weight average particle diameter of 4 to 12 μm and particles of 3 μm or more of the toner, the following formula (1)
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 is a particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter of is shown. ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value of particles having a circularity of 0.950 or more Y ≧ exp5.31 × X ^−0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
A method for producing a dry toner, wherein an absorbance at a wavelength of 340 nm is 1.0 to 2.5 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes. The method for producing a dry toner according to claim 4, wherein the absorbance at a wavelength of 340 nm is 1.3 to 2.3 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes. . The method for producing a dry toner according to claim 4 or 5, wherein the magnetic iron oxide is contained in an amount of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin. A latent image forming step of forming an electrostatic charge image on the electrostatic charge image holding member; a developing step of developing the electrostatic charge image held on the electrostatic charge image holding member with toner to form a toner image; and the toner image A transfer step of transferring the toner image transferred to the transfer material with or without an intermediate transfer member; and a fixing step of fixing the toner image transferred to the transfer material to the transfer material,
The developing step also serves to form the toner image and collect the developer remaining on the electrostatic charge image holding member after the toner image is transferred to the transfer material.
The developer is a toner having toner particles containing at least a binder resin and magnetic iron oxide, the toner has a weight average particle diameter of 4 to 12 μm, and the toner having a particle size of 3 μm or more is represented by the following formula ( 1)
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 is a particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter of is shown. ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value of particles having a circularity of 0.950 or more Y ≧ exp5.31 × X ^−0.715 (2)
[However, toner weight average particle diameter X: 4.0 to 12.0 μm]
Satisfied,
An image forming method, wherein the absorbance at a wavelength of 340 nm is 1.0 to 2.5 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes. The image forming method according to claim 7, wherein the image forming method forms a multicolor image. 9. The image forming method according to claim 7, wherein the absorbance at a wavelength of 340 nm is 1.3 to 2.3 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes. . The image forming method according to claim 7, wherein the magnetic iron oxide is contained in an amount of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin. A process cartridge that can be attached to and detached from a main body of an image forming apparatus, wherein the process cartridge develops at least an electrostatic charge image holding member and an electrostatic charge image formed on the electrostatic charge image holding member with toner, and a toner image And developing means for forming
The developing means forms the toner image and collects toner remaining on the electrostatic image holding member after the toner image is transferred to a transfer material.
The toner has toner particles containing at least a binder resin and magnetic iron oxide, the toner has a weight average particle diameter of 4 to 12 μm, and particles having a particle size of 3 μm or more are represented by the following formula (1): )
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 is a particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter of is shown. ]
More than 85% in terms of the number-based cumulative value of particles having a circularity a of 0.900 or more,
The relationship between the number-based cumulative value Y of particles having a circularity of 0.950 or more and the weight average particle diameter X of the toner is expressed by the following formula (2).
Number-based cumulative value of particles having a circularity of 0.950 or more Y ≧ exp5.31 × X ^−0.715 (2)
[However, the weight average particle diameter X of the toner is 4.0 to 12.0 μm. ]
Satisfied,
A process cartridge characterized by having an absorbance at a wavelength of 340 nm of 1.0 to 2.5 in a solution obtained by adding 5 ml of 3 mol / l hydrochloric acid to 20 mg of the toner and allowing it to stand for 50 minutes. The process cartridge according to claim 11, wherein the electrostatic charge image holding member is a photosensitive drum. 13. The process cartridge according to claim 11, wherein the absorbance at 340 nm is 1.3 to 2.3 in a solution in which 5 ml of 3 mol / l hydrochloric acid is added to 20 mg of the toner and left for 50 minutes. The process cartridge according to any one of claims 11 to 13, wherein the magnetic iron oxide is contained in an amount of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

Images