JP4109760B2 - Image forming method - Google Patents

Description

【００６４】
ここで、「粒子投影面積」とは二値化されたトナー粒子像の面積であり、「粒子投影像の周囲長」とは該トナー粒子像のエッジ点を結んで得られる輪郭線の長さと定義する。
【００６５】
本発明における円形度はトナー粒子の凹凸の度合いを示す指標であり、トナー粒子が完全な球形の場合に１．０００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【００６６】

【００６７】
【数２】

【００６８】

【００６９】
【数３】

【００７０】
具体的な測定方法としては、容器中に予め不純固形物などを除去したイオン交換水１０ｍｌを用意し、その中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルホン酸塩を加えた後、更に測定試料を０．０２ｇを加え、均一に分散させる。分散させる手段としては、超音波分散機ＵＨ−５０型（エスエムテー社製）に振動子として５φのチタン合金チップを装着したものを用い、５分間分散処理を用い、測定用の分散液とする。その際、該分散液の温度が４０℃以上とならない様に適宜冷却する。
【００７１】
トナー粒子の形状測定には、前記フロー式粒子像測定装置を用い、測定時のトナー粒子濃度が３０００〜１万個／μｌとなる様に該分散液濃度を再調整し、トナー粒子を１０００個以上計測する。計測後、このデータを用いて、トナーの円相当径や円形度頻度分布等を求める。
【００７２】
本発明に係るワックス成分は、透過電子顕微鏡（ＴＥＭ）を用いたトナーの断層面観察において、該ワックス成分が結着樹脂と相溶しない状態で、実質的に球状及び／又は紡錘形で島状に分散されている。
【００７３】

【００７４】
ワックス成分を上記の如く分散させ、トナー中に内包化させることによりトナーの劣化や画像形成装置への汚染等を防止することが出来る。特にｒ／Ｒの平均値が０．２５≦ｒ／Ｒ≦０．９０を満たす分散状態にある場合、良好な帯電性が維持され、ドット再現に優れたトナー画像を長期にわたって形成し得ることが可能となるので好ましい。また、加熱時にはワックス成分が効率良く作用する為、低温定着性と耐オフセット性を満足なものとする。
【００７５】
本発明においてトナーの断層面を観察する具体的方法としては、常温硬化性のエポキシ樹脂中にトナー粒子を十分分散させた後温度４０℃の雰囲気中で２日間硬化させ得られた硬化物を四三酸化ルテニウム、必要により四三酸化オスミウムを併用し染色を施した後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出し透過電子顕微鏡（ＴＥＭ）を用いトナーの断層形態を観察する。本発明においては、用いる低軟化点物質と外殻を構成する樹脂との若干の結晶化度の違いを利用して材料間のコントラストを付けるため四三酸化ルテニウム染色法を用いることが好ましい。代表的な一例を図６に示す。後記の実施例で得られたトナー粒子は、低軟化点物質が外殻樹脂で内包化されていることが観測された。
【００７６】
本発明に係るワックス成分は、示差走査熱量計により測定されるＤＳＣ曲線において、昇温時に５０〜１００℃の領域に最大吸熱ピークを示し、該最大吸熱ピークを含む吸熱ピークの始点のオンセット温度が４０℃以上であることが好ましく、特に該最大吸熱ピークのピーク温度と該オンセット温度の温度差が７〜５０℃の範囲であることが好ましい。
【００７７】
昇温時のＤＳＣ曲線において、上記温度領域で溶融するワックス成分を用いることにより、他の添加剤の分散性を良好なものとすることができると共に、ワックス成分自身を前述の如き分散状態に容易にコントロールすることができる。
【００７８】
これによりトナーの良好な定着性はもとより、該ワックス成分による離型効果が効果的に発現され、十分な定着領域が確保されると共に、従来から知られるワックス成分による現像性、耐ブロッキング性や画像形成装置への悪影響が排除されるのでこれらの特性が格段に向上する。特に粒子形状が球形化するに従い、トナーの比表面積は減少していくので、ワックス成分の分散状態をコントロールすることは、非常に効果的なものとなる。
【００７９】
本発明においてＤＳＣ測定では、ワックスの熱のやり取りを測定し、その挙動を観測するので、測定原理から、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。
【００８０】
測定方法は、「ＡＳＴＭ Ｄ３４１８−８２」に準じて行う。本発明に用いられるＤＳＣ極性は、ワックス成分のみを測定する場合、１回昇温−降温させ前履歴を取った後、温度速度１０℃／ｍｉｎで昇温させた時に測定されるＤＳＣ曲線を用いる。また、トナー中に含まれる状態で測定される場合には、前履歴を取らず、そのまま測定されるＤＳＣ曲線を用いる。
【００８１】
本発明において特定されるワックス成分の呈する各温度は、次にように定義される。
【００８２】
（最大吸熱ピーク）
昇温時に得られるＤＳＣ曲線において、５０〜１００℃の温度領域で最大吸熱ピークを示すピークのピークトップ温度（図７中のＭＰに相当）。
【００８３】
（吸熱ピークの始点のオンセット温度）
昇温時に得られるＤＳＣ曲線の微分値が最初に極大となる点における曲線の接線とベースラインとの交点の温度（図７中のＳＰに相当）。
【００８４】
本発明に係るワックス成分としては、パラフィンワックス、マイクロクリスタリンワックス、ペトロラクタム等の石油系ワックス及びその誘導体、モンタンワックス及びその誘導体、フィッシャートロプシュ法による炭化水素ワックス及びその誘導体、ポリエチレンに代表されるポリオレフィンワックス及びその誘導体、カルナバワックス、キャンデリラワックス等、天然ワックス及びそれらの誘導体等で、誘導体には酸化物や、ビニルモノマーとのブロック共重合物、グラフト変性物も含み、また、高級脂肪族アルコール等のアルコール；ステアリン酸、パルミチン酸等の脂肪酸或いはその化合物；酸アミド、エステル、ケトン、硬化ヒマシ油及びその誘導体、植物ワックス、動物ワックスが挙げられる。これらは単独、もしくは併用して用いることができる。
【００８５】
これらの中でもポリオレフィン、フィッシャートロプシュ法による炭化水素ワックス、石油系ワックス、高級アルコール、もしくは、高級エステルである場合、現像性や転写性の改善効果が更に高くなる。
【００８６】
該ワックス成分には、トナーの帯電性に影響を与えない範囲で酸化防止剤が添加されていても良い。
【００８７】
上述したワックス成分は、結着樹脂１００重量部に対して１〜３０重量部使用するのが好ましい。
【００８８】
本発明のトナーに用いられる結着樹脂としては、一般的に用いられているスチレン−（メタ）アクリル共重合体，ポリエステル樹脂，エポキシ樹脂，スチレン−ブタジエン共重合体が挙げられる。重合法により直接トナー粒子を得る方法においては、それらを形成するための単量体が用いられる。具体的にはスチレン；ｏ−（ｍ−，ｐ−）メチルスチレン，ｍ−（ｐ−）エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル，（メタ）アクリル酸エチル，（メタ）アクリル酸プロピル，（メタ）アクリル酸ブチル，（メタ）アクリル酸オクチル，（メタ）アクリル酸ドデシル，（メタ）アクリル酸ステアリル，（メタ）アクリル酸ベヘニル，（メタ）アクリル酸２−エチルヘキシル，（メタ）アクリル酸ジメチルアミノエチル，（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体；ブタジエン，イソプレン，シクロヘキセン，（メタ）アクリロニトリル，アクリル酸アミドの如きエン系単量体が好ましく用いられる。これらは、単独、または、一般的には出版物ポリマーハンドブック第２版ＩＩＩ−Ｐ１３９〜１９２（Ｊｏｈｎ Ｗｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を適宜混合して用いられる。理論ガラス転移温度が４０℃未満の場合にはトナーの保存安定性や耐久安定性の面から問題が生じやすく、一方７５℃を超える場合はトナーの定着点の上昇をもたらす。特にフルカラー画像を形成するためのカラートナーの場合においては各色トナーの定着時の混色性が低下し色再現性に乏しく、更にＯＨＰ画像の透明性が低下するため好ましくない。
【００８９】
結着樹脂の分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により測定される。低軟化点物質を外殻樹脂で内包化した所謂コア−シェル構造を有するトナーの場合、具体的なＧＰＣの測定方法としては、予めトナーをソックスレー抽出器を用いトルエン溶剤で２０時間抽出を行った後、ロータリーエバポレーターでトルエンを留去せしめて抽出物を得、更に低軟化点物質は溶解するが外殻樹脂は溶解しない有機溶剤（例えばクロロホルム等）を抽出物に加え十分洗浄を行った後、残留物をテトラヒドロフラン（ＴＨＦ）に溶解した溶液をポア径が０．３μｍの耐溶剤性メンブランフィルターでろ過したサンプル（ＴＨＦ溶液）をウォーターズ社製１５０Ｃを用いて測定する。カラム構成は昭和電工製Ａ−８０１、８０２、８０３、８０４、８０５、８０６、８０７を連結し標準ポリスチレン樹脂の検量線を用い分子量分布を測定し得る。本発明に係る結着樹脂の主たるピーク分子量は５０００〜１００万、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比（Ｍｗ／Ｍｎ）が、２〜１００を示すものが本発明には好ましい。
【００９０】
本発明において、上述の結着樹脂とポリエステル、ポリカーボネート等の極性を有する樹脂を併用することができる。中でも下記一般式（Ｉ）で示される繰り返し単位を分子構造中に有するポリカーボネート系樹脂を併用することが好ましく、トナーの帯電特性が向上し画像カブリや飛び散りが改善されると共に、ドット再現性に優れる高品位な画像を得ることができる。また、トナーに適度な機械的強度を付与することが可能となり、画像形成装置とのマッチングが良化するばかりか、前述の如きトナーの乾燥処理や球形化処理に対してもトナー劣化の影響を最小限とすることができるので、性能が相乗的に向上する。
【００９１】
【化３】

〔式中、Ｒは有機基を示す。〕
【００９２】
上記一般式（Ｉ）は様々な構造のものがあるが、例えば２価フェノールとカーボネート前駆体とを溶液法又は溶融法で反応せしめて製造されるあらゆる公知のポリカーボネートを使用することができ、一例を挙げれば下記一般式（ＩＩ）
【００９３】
【化４】

〔式中、Ｒ²は、水素原子、脂肪族炭化水素基、芳香族置換基であり、このＲ²が複数の場合、それらは同一であってもよいし、異なっていてもよく、ｍは、０〜４の数である。Ｚは、単結合、脂肪族炭化水素基、芳香族置換基、−Ｓ−、−ＳＯ−、−ＳＯ₂−、−Ｏ−、−ＣＯ−結合で表わされる結合などを示す。〕で表わされる構造の繰返し単位を有する重合体などが挙げられる。
【００９４】
このポリカーボネート樹脂は、様々なものを充当することができるが、通常は一般式（ＩＩＩ）〜（Ｖ）
【００９５】
【化５】

【００９６】
【化５】

【００９７】
【化７】

（式中、Ｒ²、ｍ及びＺは、前記と同じである。）で表わされる二価フェノールとホスゲンまたは炭酸エステル化合物などのカーボネート前駆体とを反応させることによって容易に製造することができる。すなわち、例えば、塩化メチレンなどの溶媒中において、公知の酸受容体や分子量調節剤の存在下、二価フェノールとホスゲンのようなカーボネート前駆体との反応により、あるいは二価フェノールとジフェニルカーボネートのようなカーボネート前駆体とのエステル交換反応によって製造される。
【００９８】
上記一般式（ＩＩＩ）〜（Ｖ）で表わされる二価フェノールとしては様々なものがあり、２，２−ビス（４−ヒドロキシフェニル）プロパン〔通称：ビスフェノールＡ〕をはじめ、例えば、ビス（４−ヒドロキシフェニル）メタン；ビス（４−ヒドロキシフェニル）フェニルメタン；ビス（４−ヒドロキシフェニル）ナフチルメタン；ビス（４−ヒドロキシフェニル）−（４−イソプロピルフェニル）メタン；ビス（３，５−ジメチル−４−ヒドロキシフェニル）メタン；１，１−ビス（４−ヒドロキシフェニル）エタン；１−ナフチル−１，１−ビス（４−ヒドロキシフェニル）エタン；１−フェニル−１，１−ビス（４−ヒドロキシフェニル）エタン；１，２−ビス（４−ヒドロキシフェニル）エタン；２−メチル−１，１−ビス（４−ヒドロキシフェニル）プロパン；２，２−ビス（３，５−ジメチル−４−ヒドロキシフェニル）プロパン；１−エチル−１，１−ビス（４−ヒドロキシフェニル）プロパン；２，２−ビス（３−メチル−４−ヒドロキシフェニル）プロパン；１，１−ビス（４−ヒドロキシフェニル）ブタン；２，２−ビス（４−ヒドロキシフェニル）ブタン；１，４−ビス（４−ヒドロキシフェニル）ブタン；２，２−ビス（４−ヒドロキシフェニル）ペンタン；４−メチル−２，２−ビス（４−ヒドロキシフェニル）ペンタン；１，１−ビス（４−ヒドロキシフェニル）シクロヘキサン；２，２−ビス（４−ヒドロキシフェニル）ヘキサン；４，４−ビス（４−ヒドロキシフェニル）ヘプタン；２，２−ビス（４−ヒドロキシフェニル）ノナン；１，１０−ビス（４−ヒドロキシフェニル）デカン；１，１−ビス（４−ヒドロキシフェニル）シクロデカンなどのジヒドロキシアリールアルカン類、ビス（４−ヒドロキシフェニル）スルホン；ビス（３，５−ジメチル−４−ヒドロキシフェニル）スルホンなどのジヒドロキシアリールスルホン類、ビス（４−ヒドロキシフェニル）エーテル；ビス（３，５−ジメチル−４−ヒドロキシフェニル）エーテルなどのジヒドロキシアリールエーテル類、４，４’−ジヒドロキシベンゾフェノン；３，３’，５，５’−テトラメチル−４，４’−ジヒドロキシベンゾフェノンなどのジヒドロキシアリールケトン類、ビス（４−ヒドロキシフェニル）スルフィド；ビス（３−メチル−４−ヒドロキシフェニルスルフィド；ビス（３，５−ジメチル−４−ヒドロキシフェニル）スルフィドなどのジヒドロキシアリールスルフィド類、ビス（４−ヒドロキシフェニル）スルホキシドなどのジヒドロキシアリールスルホキシド類、４，４’−ジヒロキシジフェニルなどのジヒドロキシジフェニル類、ヒドロキノン；ゾルシノール；メチルヒドロキノンなどのジヒドロキシベンゼン類、１，５−ジヒドロキシナフタレン；２，６−ジヒドロキシナフタレンなどのジヒドロキシナフタレン類などが挙げられる。これらの二価フェノールは、それぞれ単独で用いてもよいし、２種以上を組み合わせて用いてもよい。
【００９９】
また、炭酸エステル化合物としては、ジフェニルカーボネート等のジアリールカーボネートやジメチルカーボネート、ジエチルカーボネート等のジアルキルカーボネートが挙げられる。
【０１００】
そして、本発明で使用されるポリカーボネート系樹脂は、これらの二価フェノールの１種を用いたホモポリマーであってもよく、また２種以上を用いたコポリマーであってもよく、もしくはブレンド物であってもよい。さらに、多官能性芳香族化合物を上記二価フェノール及び／又はカーボネート前駆体と反応させて得られる熱可塑性ランダム分岐ポリカーボネート樹脂であってもよい。
【０１０１】
また、ポリカーボネート系樹脂のガラス転移温度や粘弾性を調節するために、二価フェノールの一部をエチレングリコール、ジエチレングリコール、トリエチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，４−ブタンジオール、ネオペンチルグリコール、１，４−ビス（ヒドロキシメチル）シクロヘキサン、１，４−ビス（２−ヒドロキシエチル）ベンゼン、１，４−シクロヘキサンジメタノール、ポリエチレングリコール、プロピレングリコール、水素添加ビスフェノールＡおよびその誘導体、ビスフェノールＡのエチレンオキサイド付加物、ビスフェノールＡのプロピレンオキサイド付加物、グリセリン、トリメチロールプロパン、ペンタエリスリトール等の多価アルコール等に置き換えた形の変性ポリカーボネート系樹脂も好適に使用される。この場合、単純に二価フェノール類の一部と置き換えて前記した方法により製造することも可能であるが、他の製造方法の一例として、二価フェノールと脂肪族あるいは芳香族のビスクロロホルメートとをピリジンを触媒としてメチレンクロライド溶媒中で反応させる方法などが例示されるが、もちろんその他の製造方法による合成も可能である。
【０１０２】
さらに、本発明においてはポリカーボネート系樹脂として、上述したポリカーボネートとポリスチレン、スチレン−（メタ）アクリル共重合体、ポリエステル、ポリウレタン、エポキシ樹脂、ポリオレフィン、ポリアミド、ポリスルホン、ポリシアノアリールエーテル、ポリアリーレンスルフィドなどとのブロック共重合体やアルキル（メタ）アクリレート、（メタ）アクリル酸、マレイン酸、スチレン系モノマー等をグラフトしたグラフト変性共重合体の使用も可能である。
【０１０３】
本発明において用いられるポリカーボネート系樹脂の分子量は特に制限されないが、ＧＰＣにおいて測定したピーク分子量が１０００〜５０００００の範囲にあるものが好ましく、さらに好ましくは２０００〜１０００００である。ピーク分子量が１０００よりも低いと帯電特性に悪影響がでる場合があり、５０００００よりも高いと溶融粘度が高くなりすぎ、定着性に問題を生じる場合がある。また、本発明において使用されるポリカーボネート系樹脂を製造するに際し、適当な分子量調節剤、粘弾性改善のための分岐剤、反応を促進するための触媒等必要に応じて使用することができる。
【０１０４】
本発明で使用されるポリカーボネート系樹脂の含有量は特に制限されないが、全結着樹脂１００重量部に対して通常０．１〜５０重量部、好ましくは０．２〜４０重量部、さらに好ましくは０．５〜３０重量部である。０．１重量部未満の場合には、添加効果が発現されず、また、５０重量部を超えるとトナーの帯電性や定着性や画像形成装置とのマッチングに問題を生じる様になる。
【０１０５】
本発明において、前記の如き極性樹脂をトナー表面に設けられる最外殻樹脂層として用いることは、好適な実施形態の一つである。
【０１０６】
この時、最外殻樹脂層に用いられる極性樹脂のガラス転移温度は、耐ブロッキング性のさらなる向上のため外殻樹脂層のガラス転移温度以上に設計されること、さらに定着性を損なわない程度に架橋されていることが好ましい。また、該最外殻樹脂層には帯電性向上のため極性樹脂や荷電制御剤が含有されていることが好ましい。
【０１０７】
該最外殻層を設ける方法としては、特に限定されるものではないが例えば以下のような方法が挙げられる。
【０１０８】
１．重合反応後半、または終了後、反応系中に必要に応じて、極性樹脂、荷電制御剤、架橋剤等を溶解、分散したモノマーを添加し重合粒子に吸着させ、重合開始剤を添加し重合を行う方法。
【０１０９】
２．必要に応じて、極性樹脂、荷電制御剤、架橋剤等を含有したモノマーからなる乳化重合粒子またはソープフリー重合粒子を反応系中に添加し、重合粒子表面に凝集、必要に応じて熱等により固着させる方法。
【０１１０】
３．必要に応じて、極性樹脂、荷電制御剤、架橋剤等を含有したモノマーからなる乳化重合粒子またはソープフリー重合粒子を乾式で機械的にトナー粒子表面に固着させる方法。
【０１１１】
本発明のトナーに特定の有機金属化合物を含有させることは、トナーの電子写真特性の向上と共に帯電部材通過時の帯電制御特性を改善するので好ましく、特にアゾ系鉄化合物や有機ジルコニウム化合物が好適である。
【０１１２】
アゾ系鉄化合物としては、下記一般式のものが好ましく用いられる。
【０１１３】
【化８】

［式中、Ｘ₁およびＸ₂は水素原子、低級アルキル基、低級アルコキシ基、ニトロ基またはハロゲン原子を表わし、Ｘ₁とＸ₂は同じであっても異なっていてもよく、ｍおよびｍ’は１〜３の整数を表わし、Ｒ₁およびＲ₃は水素原子、Ｃ₁〜Ｃ₁₈のアルキル基、Ｃ₂〜Ｃ₁₈のアルケニル基、スルホンアミド基、メシル基、スルホン酸基、カルボキシエステル基、ヒドロキシ基、Ｃ₁〜Ｃ₁₈のアルコキシ基、アセチルアミノ基、ベンゾイルアミノ基またはハロゲン原子を表わし、Ｒ₁とＲ₃は同じであっても異なっていてもよく、ｎおよびｎ’は１〜３の整数を表わし、Ｒ₂およびＲ₄は水素原子またはニトロ基を表わし、Ａ⁺はカチオンイオンを示し、アンモニウムイオン、水素イオン、ナトリウムイオン、カリウムイオン又はそれらの混合イオンを有する。］
【０１１４】
上記アゾ系鉄錯体化合物は負荷電制御剤としても用いられる。該化合物は公知の方法により合成できる。
【０１１５】
前記一般式のアゾ系鉄錯体化合物の代表的な具体例としては、次のような化合物が挙げられる。
【０１１６】
【化９】

【０１１７】
【化１０】

【０１１８】
本発明においては、前記トナーを重合法にて形成する際、使用する重合性単量体中にカーボンブラックと前記アゾ系鉄錯体化合物を前分散させることで、カーボンブラックの分散性向上の効果が著しい。これはより高濃度で分散させるために分散液が高粘度となり、高シェアで分散が行われるためである。
【０１１９】
一方、有機ジルコニウム化合物の具体例としては、（ｉ）金属元素としてジルコニウムを有し、配位子として芳香族ジオール、芳香族ヒドロキシカルボン酸、又は芳香族ポリカルボン酸を配位しているジルコニウム錯体あるいはジルコニウム錯塩、（ｉｉ）金属イオンとしてジルコニウムイオンを有し、酸イオンとして芳香族カルボン酸イオン、芳香族ヒドロキシカルボン酸イオン、又は芳香族ポリカルボン酸イオンを有しているカルボン酸ジルコニウム塩、等が挙げられる。
【０１２０】
なお、該ジルコニウムには、ジルコニウム元素基準でハフニウム元素を２０ｗｔ％未満で含んでいても良い。また、ジルコニウムの錯化合物及びジルコニウムの芳香族カルボン酸塩の配位子として、芳香族ジオール、芳香族ヒドロキシカルボン酸又は芳香族ポリカルボン酸を２〜４個キレート形成しているものが好ましく、さらには、２〜３個有しているものが好ましい。更に、キレート形成数の異なる錯体、錯塩、あるいは配位子の異なる錯体、錯塩の混合物であっても良い。また、酸イオンのイオン化数が異なる塩の混合物であっても良い。
【０１２１】
芳香族ジオール、芳香族ヒドロキシカルボン酸、又は芳香族ポリカルボン酸のジルコニウム錯体あるいはジルコニウム錯塩としては、一般式（Ｂ−１）で表わせる有機ジルコニウム化合物が好ましい。
【０１２２】
【化１１】

【０１２３】
一般式（Ｂ−１）において、Ａｒは置換基としてアルキル基、アリール基、アルアルキル基、シクロアルキル基、アルケニル基、アルコキシ基、アリールオキシ基、水酸基、アルコキシカルボニル基、アリールオキシカルボニル基、アシル基、アシルオキシ基、カルボキシル基、ハロゲン、ニトロ基、シアノ基、アミノ基、アミド基、カルバモイル基を有していてもよい。芳香族残基を表わし、Ｘ，Ｙは−０−、−ＣＯ−Ｏ−を表わし、Ｘ，Ｙは同じであっても異なっていてもよく、Ｌは中性配位子、水、アルコール、アンモニア、アルキルアミン、ピリジンを表わし、Ｃ１は１価のカチオン、水素、１価の金属イオン、アンモニウム、アルキルアンモニウムを表わし、Ｃ２は２価のカチオン、２価の金属イオンを表し、ｎは２、３、４を表わし、ｍは０、２、４を表わす。各錯体または錯塩において配位子となる芳香族カルボン酸類、芳香族ジオール類は同じものであっても異なるものであってもよい。またｎ，ｍの数の異なる錯化合物の混合物であっても良い。結着樹脂中への錯体、錯塩の分散性向上の観点あるいは帯電性向上の観点から、芳香族残基としては、ベンゼン環、ナフタレン環、アントラセン環、フェナントレン環が好ましく、置換基としてはアルキル基、カルボキシル基、水酸基が好ましく、Ｌとしては水が好ましく、Ｃ１としては水素、ナトリウム、カリウム、アンモニウム、アルキルアンモニウムが好ましい。
【０１２４】
更に好ましいジルコニウム錯体あるいは塩は一般式（Ｂ−２）、（Ｂ−３）、（Ｂ−４）で表わせる有機ジルコニウム化合物である。
【０１２５】
【化１２】

【０１２６】
一般式（Ｂ−２）、（Ｂ−３）、（Ｂ−４）において、Ｒは水素、アルキル基、アリール基、アルアルキル基、シクロアルキル基、アルケニル基、アルコキシ基、アリールオキシ基、水酸基、アシルオキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アシル基、カルボキシル基、ハロゲン、ニトロ基、アミノ基、カルバモイル基を表わし、相互に連結して脂肪族環、芳香環あるいは複素環を形成しても良く、この場合この環に置換基Ｒを有していても良く、置換基Ｒは１から８個持っていてもよく、それぞれ同じであっても、異なっていてもよく、Ｃは１価のカチオン、水素、アルカリ金属、アンモニウム、アルキルアンモニウムを表わし、１は１〜８の整数を表わし、ｎは２、３、４を表わし、ｍは０、２、４を表わし、各錯体または塩において配位子となる芳香族カルボン酸類、芳香族ジオール類は同じ物であっても異なるものであってもよい。またｎ，ｍの数の異なる錯化合物の混合物であっても良い。結着樹脂中へのジルコニウム錯体あるいは塩の分散性向上の観点あるいは帯電性向上の観点から、置換基Ｒとしてはアルキル基、アルケニル基、カルボキシル基、水酸基が好ましく、Ｃとしては水素、ナトリウム、カリウム、アンモニウム、アルキルアンモニウムが好ましい。特に好ましいのは、カウンターイオンを有さない、一般式においてｎ＝２の場合のジルコニウム中性錯体であり、優れた環境安定性が得られ、結着樹脂中への分散性にも優れ、良好な耐久性が得られる。
【０１２７】
本発明に用いられるジルコニウム錯体あるいは塩は、六配位または八配位の錯化合物で、八配位の中には、配位子が橋かけした複核錯化合物となり示性式上六配位となる錯化合物がある。このような錯化合物の構造の代表的なものを、以下の一般化学式（Ｂ−５）〜（Ｂ−９）でその構造を例示する。以下の構造の中には配位子Ｌを持たないものも包含する。
【０１２８】
【化１３】

【０１２９】
【化１４】

【０１３０】
また、芳香族カルボン酸のジルコニウム塩としては、一般式（Ｂ−１０）、（Ｂ−１１）で表わせる有機ジルコニウム化合物が好ましい。
【０１３１】
【化１５】

【０１３２】
一般式（Ｂ−１０）、（Ｂ−１１）において、Ａｒは置換基としてアルキル基、アリール基、アルアルキル基、シクロアルキル基、アルケニル基、アルコキシ基、アリールオキシ基、水酸基、アシルオキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アシル基、カルボキシル基、ハロゲン、ニトロ基、シアノ基、アミノ基、アミド基、カルバモイル基を有していてもよい、芳香族残基を表わし、Ａ１は１価のアニオン、ハロゲンイオン、水酸イオン、硝酸イオンを表わし、Ａ２は２価のアニオン、硫酸イオン、リン酸水素イオンを表し、ｎは１、２、３、４を表わす。各金属塩において酸イオンとなる芳香族カルボン酸類、芳香族ジオール類は同じものであっても異なるものであってもよい。また、ｎの数が異なる塩の混合物であっても良い。結着樹脂中への金属塩の分散性向上の観点あるいは帯電性向上の観点から、芳香族残基としては、ベンゼン環、ナフタレン環、アントラセン環、フェナントレン環が好ましく、置換基としてはアルキル基、カルボキシル基、水酸基、アシルオキシ基が好ましく、一般式（Ｂ−１０）ではｎが４のもの、一般式（Ｂ−１１）ではｎが２のものが好ましい。
【０１３３】
更に好ましい金属塩は一般式（Ｂ−１２）、（Ｂ−１３）で表わせるジルコニウム塩である。
【０１３４】
【化１６】

【０１３５】
一般式（Ｂ−１２）及び（Ｂ−１３）において、Ｒは水素、アルキル基、アリール基、アルアルキル基、シクロアルキル基、アルケニル基、アルコキシ基、アリールオキシ基、水酸基、アルコキシカルボニル基、アリールオキシカルボニル基、アシルオキシ基、アシル基、カルボキシル基、ハロゲン、ニトロ基、アミノ基、アミド基、カルバモイル基を表わし、相互に連結して脂肪族環、芳香環あるいは複素環を形成しても良く、この場合この環に置換基Ｒを有していても良い、置換基Ｒは１から８個持っていてもよく、それぞれ同じであっても、異なっていてもよく、Ａ１は１価のアニオン、ハロゲンイオン、水酸イオン、硝酸イオンを表わし、Ａ２は２価のアニオン、硫酸イオン、リン酸水素イオンを表し、１は１〜８の整数を表わし、ｎは２、３、４を表わす。各金属塩において酸イオンとなる芳香族カルボン酸類、芳香族ジオール類は同じものであっても異なるものであってもよい。また、ｎの数が異なる塩の混合物であっても良い。結着樹脂中への金属塩の分散性向上の観点あるいは帯電性向上の観点から、置換基としてはアルキル基、アルケニル基、カルボキシル基、水酸基、アシルオキシ基が好ましく、一般式（Ｂ−１２）ではｎが４のもの、一般式（Ｂ−１３）ではｎが２のものが好ましく、優れた環境安定性が得られ、結着樹脂中への分散性にも優れ、優れた耐久性が得られる。
【０１３６】
本発明の有機ジルコニウム化合物は、塩化酸化ジルコニウム、硫酸ジルコニウム、有機酸ジルコニウムなどのジルコニウム化合物を水、アルコール、アルコール水溶液に溶解し、芳香族カルボン酸、芳香族ジオールおよびこれらのアルカリ金属塩を添加するか、あるいは芳香族カルボン酸、芳香族ジオールとアルカリ剤を添加することにより合成される。これらの有機ジルコニウム化合物は、アルコール水溶液などで再結晶し、アルコール洗浄で精製する。また、錯塩の場合は、生成物を鉱酸、アルカリ剤、アミン剤で処理することにより種々のカウンターイオンを持つ錯塩が得られる。本発明においては、ジルコニウム錯塩のカウンターイオンに水素イオン、アルカリ金属イオン、アンモニウムイオンなど複数種有しているものも含む。
【０１３７】
以下に、本発明に用いられる有機ジルコニウム化合物の具体例を挙げるが、ここでは、示性式を示す。水分子を２〜４個配位しているものも含まれるが、ここでは水分子の記載を省略する。また、カウンターイオンは複数種有するものも含むが、ここでは一番多いカウンターイオンのみを記載する。
【０１３８】
【化１７】

【０１３９】
【化１８】

【０１４０】
【化１９】

【０１４１】
【化２０】

【０１４２】
【化２１】

【０１４３】
【化２２】

【０１４４】
【化２３】

【０１４５】
【化２４】

【０１４６】
本発明に用いられる着色剤は、以下に示すイエロー着色剤，マゼンタ着色剤及びシアン着色剤が挙げられ、黒色着色剤としてカーボンブラック，磁性体または以下に示すイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用される。
【０１４７】
本発明に用いられるカーボンブラックの粒径は２５〜８０ｎｍであることが好ましい。
【０１４８】
カーボンブラックの粒径に関しては、２５ｎｍよりも小さいと、一次粒径が微細なため、十分な分散が得られにくく、使いこなすのが困難である。
【０１４９】
８０ｎｍよりも大きい場合には、良好に分散してもトナーとしての着色力の不足から、低濃度の画像しか得られない、或いはトナー消費量が増大する等の不都合が生ずる。
【０１５０】
カーボンブラックの粒径に関しては、粒径が３５〜７０ｎｍであることがより好ましく、転写残トナーの帯電部材による帯電極性及び帯電量を制御がより確実に且つ均一になされ、トナーの帯電量の安定性及びトナー着色力の面でもより有利である。
【０１５１】
本発明におけるトナー中のカーボンブラックの粒径は、透過型電子顕微鏡で拡大した写真を撮影して測定することができる。
【０１５２】
本発明に用いられるカーボンブラックのＤＢＰ吸油量は４０〜１５０ｍｌ／１００ｇであることが望ましい。
【０１５３】
ＤＢＰ吸油量が４０ｍｌ／１００ｇ未満のストラクチャーの短いカーボンブラックではトナーの帯電量が低くなりすぎ易く、１５０ｍｌ／１００ｇを超えると強固な長ストラクチャーのためカーボンブラックの微細な分散が得られにくい。
【０１５４】
ＤＢＰ吸油量の測定は、ＡＳＴＭ法Ｄ２４１４−７９に準拠して行う。
【０１５５】
本発明に用いられるカーボンブラックは、窒素吸着比表面積が１００ｍ²／ｇ以下、揮発分が２％以下であることが望ましい。この本発明に係わるカーボンブラックは、通常トナーに多く用いられているものよりも比表面積が小さく、揮発分も少ない。
【０１５６】
比表面積が小さく、揮発分の少ないカーボンブラックは、重合阻害性の官能基が少ないことから、重合阻害性が低い利点があり、トナー中でのカーボンブラックの均一な分散にも有利である。
【０１５７】
窒素吸着比表面積に関しては、１００ｍ²／ｇよりも大きくなると重合阻害性を生じ易くなる。また、揮発分が２％を超えるカーボンブラックは、表面に重合阻害性の官能基が多数存在するため使用に適さない。
【０１５８】
窒素吸着比表面積の測定は、ＡＳＴＭ法Ｄ３０３７−７８に準拠して行う。
【０１５９】
また、トナーを重合法で製造する場合、本発明に係わるアゾ系鉄化合物やジルコニウム錯体あるいはジルコニウム塩と共にカーボンブラックを前分散する工程を行うことが望ましい。より高濃度でカーボンブラックを分散するためせん断力がかかり易くなり、分散性向上の効果が大きくなる。
【０１６０】
イエロー着色剤としては、縮合アゾ化合物，イソインドリノン化合物，アンスラキノン化合物，アゾ金属錯体，メチン化合物，アリルアミド化合物に代表される化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメントイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８、１８０等が好適に用いられる。
【０１６１】
マゼンタ着色剤としては、縮合アゾ化合物，ジケトピロロピロール化合物，アンスラキノン，キナクリドン化合物，塩基染料レーキ化合物，ナフトール化合物，ベンズイミダゾロン化合物，チオインジゴ化合物，ペリレン化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４が特に好ましい。
【０１６２】
シアン着色剤としては、銅フタロシアニン化合物及びその誘導体，アンスラキノン化合物，塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６等が特に好適に利用できる。
【０１６３】
これらの着色剤は、単独又は混合し更には固溶体の状態で用いることができる。着色剤は、色相，彩度，明度，耐候性，ＯＨＰ透明性，トナー粒子中への分散性の点から選択される。該着色剤の添加量は、樹脂成分１００重量部に対し１〜２０重量部使用するのが好ましい。
【０１６４】
黒色着色剤として磁性体を用いた場合には、他の着色剤と異なり、樹脂１００重量部に対し４０〜１５０重量部使用するのが好ましい。
【０１６５】
本発明には、前述のアゾ系鉄化合物やジルコニウム錯体あるいはジルコニウム塩と共に公知の荷電制御剤を併用することができ、特に帯電スピードが速く、且つ、一定の帯電量を安定して維持できる荷電制御剤が好ましい。更に、トナー粒子を直接重合法を用いる場合には、重合阻害性が無く水系分散媒体への可溶化物の無い荷電制御剤が好ましい。具体的化合物としては、ネガ系荷電制御剤としてサリチル酸、ナフトエ酸、ダイカルボン酸の如き芳香族カルボン酸の金属化合物；スルホン酸又はカルボン酸基を側鎖に持つ高分子型化合物；ホウ素化合物；尿素化合物；ケイ素化合物；カリークスアレーン等が挙げられる。ポジ系荷電制御剤として、四級アンモニウム塩；該四級アンモニウム塩を側鎖に有する高分子型化合物；グアニジン化合物；イミダゾール化合物等が挙げられる。
【０１６６】
しかしながら、本発明において荷電制御剤の添加は必須ではなく、二成分現像方法を用いた場合においては、キャリヤとの摩擦帯電を利用し、非磁性一成分ブレードコーティング現像方法を用いた場合においては、ブレード部材やスリーブ部材との摩擦帯電を積極的に利用することでトナー粒子中に必ずしも荷電制御剤を含む必要はない。
【０１６７】
本発明のトナーに無機微粉体を添加することは、現像性、転写性、帯電安定性、流動性及び耐久性向上のために好ましい実施形態である。該無機微粉体としては公知のものが使用可能であるが、特にシリカ，アルミナ，チタニアあるいはその複酸化物の中から選ばれることが好ましい。更には、シリカであることがより好ましい。例えば、かかるシリカは硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及びアルコキシド，水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、またＮａ₂Ｏ，ＳＯ₃ ^2-等の製造残渣の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム，塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能でありそれらも包含する。
【０１６８】
本発明に用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与え、トナー１００重量部に対してシリカ微粉末０．１〜８重量部、好ましくは０．５〜５重量部、さらに好ましくは１．０を超えて３．０重量部まで使用するのが特に良い。
【０１６９】
また、本発明に用いられる無機微粉体は、必要に応じ、疎水化，帯電性制御等の目的でシリコーンワニス，各種変性シリコーンワニス，シリコーンオイル，各種変性シリコーンオイル，シランカップリング剤，官能基を有するシランカップリング剤，その他有機硅素化合物，有機チタン化合物等の処理剤で、あるいは、種々の処理剤で併用して処理されていることも可能であり好ましい。
【０１７０】
比表面積はＢＥＴ法に従って、比表面積測定装置オートソーブ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて比表面積を算出した。
【０１７１】
高い帯電量を維持し、低消費量及び高転写率を達成するためには、無機微粉体は少なくともシリコーンオイルで処理されることがさらに好ましい。
【０１７２】
本発明のトナーにおいては、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばテフロン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末などの研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末などの流動性付与剤；ケーキング防止剤、あるいは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることもできる。
【０１７３】
本発明のトナーを製造する方法としては、樹脂，低軟化点物質からなる離型剤，着色剤，荷電制御剤等を加圧ニーダーやエクストルーダー又はメディア分散機を用い均一に分散せしめた後、機械的又はジェット気流下でターゲットに衝突させ、所望のトナー粒径に微粉砕化せしめた後（必要により、トナー粒子の平滑化及び球形化の工程を付加）、更に分級工程を経て粒度分布をシャープにせしめトナーにする粉砕方法によるトナーの製造方法の他に、特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報，特開昭５９−５３８５６号公報，特開昭５９−６１８４２号公報に述べられている懸濁重合方法を用いて直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合方法又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合法に代表される乳化重合方法等を用いトナーを製造することが可能である。
【０１７４】
粉砕法を用いてトナーを製造する方法においては、トナー粒子の形状を所望の円形度頻度分布の範囲に納めることが困難であり、溶融スプレー法においては、ある程度の円形度を得ることができるが、得られるトナーの粒度分布が広くなり易い傾向があると共に、トナーの表面状態をコントロールすることが困難である。他方、分散重合法においては、得られるトナーは極めてシャープな粒度分布を示すが、使用する材料の選択が狭いことや有機溶剤の利用が廃溶剤の処理や溶剤の引火性に関する観点から製造装置が複雑で煩雑化しやすい。ソープフリー重合に代表される乳化重合方法は、トナーの粒度分布が比較的揃うため有効であるが、使用した乳化剤や重合開始剤末端がトナー粒子表面に存在し時に環境特性を悪化させやすい。
【０１７５】
本発明においては、トナー粒子の円形度頻度分布のコントロールが重要であり、比較的容易に円相当個数平均径が２〜６μｍの微粒子トナーが得られる常圧下、または、加圧下での乳化重合法又は懸濁重合方法を用い、予め得られた重合体にメディアを用い定形化したり、直接加圧衝突板に重合体を衝突せしめる方法や、更には得られた重合体を水系中にて凍結せしめたり、塩折や反対表面電荷を有する粒子をｐＨ等の条件を考慮することで合体し、凝集、合一せしめる凝集方法が特に好ましい。さらに、一旦得られた重合粒子に更に単量体を吸着せしめた後、重合開始剤を用い重合せしめるシード重合方法も本発明に好適に利用することができる。
【０１７６】
トナーの製造方法として直接重合方法を利用する場合、トナー粒子の円形度頻度分布及び粒径頻度分布の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件（例えばローターの周速、パス回数、撹拌羽根形状等の撹拌条件や容器形状）又は、水溶液中での固形分濃度等を制御することにより所定のトナー粒子を得ることができる。また、前述の如くトナー粒子の乾燥に用いられる円錘型乾燥機の撹拌条件、処理時間を調整することによっても所定のトナー粒子を得ることができる。
【０１７７】
直接重合法によりトナーを製造する際、用いられる重合開始剤として例えば、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系又はジアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシドの如き過酸化物系重合開始剤が用いられる。該重合開始剤の使用量は、目的とする重合度により変化するが一般的には重合性単量体に対し０．５〜２０重量％用いられる。重合開始剤の種類は、重合法により若干異なるが、十時間半減期温度を参考に、単独又は混合して使用される。
【０１７８】
重合度を制御するため公知の架橋剤，連鎖移動剤，重合禁止剤等を更に添加し用いても良い。
【０１７９】
トナーの製法として分散安定剤を用いた懸濁重合法を利用する場合、用いる分散安定剤としては、無機化合物として、リン酸三カルシウム，リン酸マグネシウム，リン酸アルミニウム，リン酸亜鉛，炭酸カルシウム，炭酸マグネシウム，水酸化カルシウム，水酸化マグネシウム，水酸化アルミニウム，メタケイ酸カルシウム，硫酸カルシウム，硫酸バリウム，ベントナイト，シリカ，アルミナ等が挙げられる。有機化合物としては、ポリビニルアルコール，ゼラチン，メチルセルロース，メチルヒドロキシプロピルセルロース，エチルセルロース，カルボキシメチルセルロースのナトリウム塩，ポリアクリル酸及びその塩，デンプン等が挙げられる。これらを水相に分散させて使用できる。これら分散安定剤は、重合性単量体１００重量部に対して０．２〜２０重量部を使用することが好ましい。
【０１８０】
分散安定剤として、無機化合物を用いる場合、市販のものをそのまま用いても良いが、細かい粒子を得るために、分散媒体中にて該無機化合物の微粒子を生成しても良い。例えば、リン酸三カルシウムの場合、高速撹拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合すると良い。
【０１８１】
これら分散安定剤の微細な分散の為に、０．００１〜０．１重量部の界面活性剤を併用してもよい。これは上記分散安定剤の所期の作用を促進するためのものであり、例えば、ドデシルベンゼン硫酸ナトリウム，テトラデシル硫酸ナトリウム，ペンタデシル硫酸ナトリウム，オクチル硫酸ナトリウム，オレイン酸ナトリウム，ラウリル酸ナトリウム，ステアリン酸カリウム，オレイン酸カルシウム等が挙げられる。
【０１８２】
本発明で使用するトナーの製造方法として直接重合法を用いる場合においては、以下の如き製造方法が可能である。
【０１８３】
重合性単量体中に、低軟化点物質からなる離型剤，着色剤，荷電制御剤，重合開始剤その他の添加剤を加え、ホモジナイザー，超音波分散機等によって均一に溶解又は分散せしめた単量体組成物を、分散安定剤を含有する水相中に通常の撹拌機またはホモミキサー，ホモジナイザー等により分散せしめる。好ましくは単量体組成物の液滴が所望のトナー粒子のサイズを有するように撹拌速度，撹拌時間を調整し、造粒する。その後は分散安定剤の作用により、粒子状態が維持され、且つ粒子の沈降が防止される程度の撹拌を行えば良い。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行うのが良い。重合反応後半に昇温しても良く、更に、本発明における画像形成方法における耐久性向上の目的で、未反応の重合性単量体、副生成物等を除去するために反応後半、又は、反応終了後に一部水系媒体を反応系から留去しても良い。反応終了後、生成したトナー粒子を洗浄・濾過により回収し、乾燥する。懸濁重合法においては、通常単量体組成物１００重量部に対して水３００〜３０００重量部を分散媒体として使用するのが好ましい。
【０１８４】
次に本発明の画像形成方法を添付図面を参照しながら以下に説明する。
【０１８５】
二成分現像プロセス：
図１を参照しながら、本発明の画像形成方法の実施例の一例として用いた、磁気ブラシ現像用二成分系現像剤を使用する現像器を用いた画像形成装置を模式的に示した図で説明する。
【０１８６】
図１において、感光体２の帯電手段である帯電ブラシローラー５（ナイロン繊維にカーボンブラックを分散させて抵抗調整された、繊維の太さが６デニール、ブラシの繊維の長さは３ｍｍ、ブラシ密度は１平方インチ当たり１０万本、感光体回転と逆方向に周速１２０％で回転）を感光体２と接触させてバイアス印加して帯電し、レーザー光による露光６（６００ｄｐｉ、２値）により、感光体２に静電荷潜像を形成する。現像器１５の現像剤担持体１上のトナーと磁性キャリアとを有する二成分系現像剤で形成された磁気ブラシを感光体２と接触させて、反転現像法により感光体２の静電荷潜像を現像してトナー画像を形成する。
【０１８７】
現像剤担持体１には、バイアス印加手段により少なくとも直流バイアスが印加される（直流成分として現像コントラストが５００Ｖとなるように設定、交流成分としては１．８ｋＶを印加）。
【０１８８】
感光体２上のトナー画像は、搬送されてくる転写材４へ、転写手段である転写コロナ帯電器３（感光体２とは非接触）により転写され、転写材４上のトナー画像は、ヒータ８を内包する加熱ローラ７と加圧ローラ９とを有する加熱加圧定着手段により転写材４に定着される。感光体２としては、感光体表面の水に対する接触角が８５度以上である感光体製造例１の感光体を使用した。転写工程後の感光体２上の転写残余のトナーは、クリーニング工程を経由することはない。イレース露光１１により除電された感光体２は、再度帯電ブラシローラー５で帯電され、露光６により静電荷潜像を形成する。転写残余のトナーを有する感光体２は、現像剤担持体１上の磁気ブラシによる静電荷潜像の現像とともに、転写残余のトナーの現像剤担持体１への回収がおこなわれる。現像兼クリーニング工程後の感光体２上のトナー画像は、搬送されてくる転写材４上へ転写コロナ帯電器３により転写され、転写工程後の感光体２は、イレース露光１１で除電され、帯電ブラシローラー５で再度帯電され、以後同様な工程が繰り返し実施される。
【０１８９】
図２に、図１の現像部の拡大図を示す。図２において、感光体２と、現像剤担持体１上の二成分系現像剤２０で形成されている磁気ブラシと接触している。
【０１９０】
現像剤担持体１は、例えばアルミニウム、ＳＵＳ３１６の如き非磁性材料で構成されている。現像剤担持体１は現像器１５の左下方壁に容器長手方向に形成した横長開口に右略半周面を現像器１５内へ突入させ、左略半周面を容器外へ露出させて回転自在に軸受けさせて横設してあり、矢印方向に回転駆動される。
【０１９１】
現像剤担持体１内に挿入し図示の位置姿勢に位置決め保持した固定磁界発生手段としての固定の永久磁石（マグネット）であり、現像剤担持体１が回転駆動されてもこの磁石２４は図示の位置・姿勢にそのまま固定保持される。この磁石２４はＮ極の磁極２２，２５及び２６を有し、Ｓ極の磁極２１及び２３の５磁極を有する。磁石２４は永久磁石に代えて電磁石を配設してもよい。
【０１９２】
１３は現像剤担持体１を配設した現像剤供給器開口の上縁側に、基部を容器側壁に固定した現像剤規制部材としての非磁性ブレードであり、例えばＳＵＳ３１６を横断面路図の如くＬ宇形に曲げ加工したものである。
【０１９３】
１４は非磁性ブレード（現像剤規制部材）１３の下面側に上面を接触させ前端面を現像剤案内面とした磁性キャリア限定部材である。非磁性ブレード１３及び磁性キャリア返し部材１４などによって構成される部分が規制部である。
【０１９４】
２０はトナー及び磁性キャリアを有する現像剤層である。１６は非磁性トナーである。
【０１９５】
２７はトナー濃度検出センサー（不図示）によって得られる出力に応じて作動するトナー補給ローラーである。センサーとしては、現像剤の体積検知方式、圧電素子、インダクタンス変化検知素子、交番バイアスを利用したアンテナ方式、光学濃度を検知する方式を利用することができる。該ローラーの回転または停止によって非磁性トナー１６の補給を行う。トナー１６が補給されたフレッシュな現像剤は現像剤搬送ローラ１７によって搬送されながら混合及び撹拌される。従ってこの搬送中において補給されたトナーにトリボ付与が行われる。１８はしきり板で現像器の長手方向両端部において切り欠かれており、この部分でスクリュー１７によって搬送されたフレッシュな現像剤がスクリュー１９へ受け渡される。
【０１９６】
Ｎ磁極２６は搬送極である。現像後の回収現像剤を容器内に回収し、さらに容器内の現像剤を規制部まで搬送する。
【０１９７】
Ｎ磁極２６付近では、現像剤担持体１に近接して設けたスクリュー１９によって搬送されてきたフレッシュな現像剤と現像後の回収現像剤とを交換する。
【０１９８】
非磁性ブレード１３の端部と現像剤担持体１面との距離ｄは４００μｍとした。好ましいｄの設定範囲は１００〜９００μｍである。この距離が１００μｍより小さいとキャリア粒子がこの間に詰まり現像剤層にムラを生じやすいと共に良好な現像を行うのに必要な現像剤を塗布することが出来ず濃度の薄いムラの多い現像画像しか得られない場合がある。一方、この距離が９００μｍより大きいと現像剤担持体１上へ塗布される現像剤量が増加し所定の現像剤層厚の規制が行えず、潜像担持体への磁性粒子付着が多くなると共に現像剤の循環、現像剤限定部材１４による現像規制が弱まりトナーのトリボが不足しカブリやすくなる傾向がある。
【０１９９】
現像剤担持体１上の現像剤層の厚さを、現像剤担持体１と感光体２との対向空隙距離よりも若干大きくすることが好ましい。この距離は、４００μｍに設定した。好ましくは、５０〜８００μｍに設定するのが良い。
【０２００】
一成分現像プロセス：
図３を参照しながら、本発明の画像形成方法の実施例の別の一例として、クリーニングブレード等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する画像形成方法を模式的に示した図で説明する。
【０２０１】
接触帯電手段である帯電ローラ３１により感光体３６を帯電し、レーザー光４０で画像部分を露光して静電荷潜像を形成する。現像器３２にあるトナー３０をトナー塗布ローラ３５及び塗布ブレード３３によりトナー担持体３４上に塗布し、トナー担持体３４上のトナーで感光体３６の静電荷潜像を反転現像法により現像し、トナー画像を感光体３６上に形成する。トナー担持体３４にはバイアス印加手段４１により少なくとも直流バイアスが印加される。感光体３６上のトナー画像は搬送されて来る転写材３８上へ、バイアス印加手段４２によりバイアスが印加されている転写手段である転写ローラー３７により転写され、転写材上のトナー画像は、加熱ローラと加圧ローラーとを有する加熱加圧定着手段４３により定着される。
【０２０２】
感光体３６として、感光体表面の水に対する接触角が８５度以上である感光体製造例１の感光体を使用した。転写工程後の感光体３６上の転写残余のトナーは、ブレードクリーニング手段の如きクリーニング手段によりクリーニング工程を経由することなく、帯電ローラー３１の所まで搬送される。転写残余のトナーを有する感光体３６は、再度、帯電ローラー３１で帯電され、帯電後にレーザー光４０の露光により静電荷潜像が形成される。転写残余のトナーを有する感光体３６は、トナー担持体３４上のトナーによる静電荷潜像の現像とともに、転写残余のトナーの現像剤担持体３４への回収がおこなわれる。現像兼クリーニング工程後の感光体３６上のトナー画像は、転写ローラー３７により搬送されてくる転写材３８上に転写され、転写工程後の感光体３６は、帯電ローラー３１により再度帯電され、以後同様な工程が繰り返し実施される。
【０２０３】
反転現像方法において、現像同時クリーニングを実施するための好ましい現像条件としては、感光体表面の暗部電位（Ｖ_d）と明部電位（Ｖ_l）とトナー担持体に印加される直流バイアス（Ｖ_DC）とが、｜Ｖ_d−Ｖ_DC｜＞｜Ｖ_l−Ｖ_DC｜の関係を満足するように設定するのが良い。より好ましくは、｜Ｖ_d−Ｖ_DC｜の値が｜Ｖ_l−Ｖ_DC｜の値よりも１０Ｖ以上大きい方が良い。
【０２０４】
中間転写ベルトを用いた画像形成プロセス：
図４は中間転写ベルトを用いたカラー画像形成装置（複写機あるいはレーザービームプリンター）の概略的説明図である。
【０２０５】
５１は第１の画像担持体としてのドラム状の電子写真感光体（以下感光ドラムと記す）であり、矢印の方向に所定の周速度（プロセススピード）で回転駆動される。
【０２０６】
感光ドラム５１は回転過程で、一次帯電器５２により所定の極性・電位に一様に帯電処理され、次いで不図示の像露光手段による露光５３を受ける。このようにして目的のカラー画像の第１の色成分像（例えばイエロー色成分像）に対応した静電潜像が形成される。
【０２０７】
次いで、その静電潜像が第１の現像器（イエロー色現像器７１）により第１色であるイエロー成分像に現像される。この時第２〜第４の現像器、即ちマゼンタ現像器７２、シアン色現像器７３、およびブラック色現像器７４は作動しておらず、感光ドラム５１には作用していないので、上記第１色のイエロー成分画像は上記第２〜第４の現像器による影響を受けない。
【０２０８】
中間転写ベルト７７は、矢印の方向に感光ドラム５１と同じ周速度で回転駆動される。
【０２０９】
感光ドラム５１上に形成された上記第１色のイエロー成分像が、感光ドラム５１と中間転写ベルト７７とのニップ部を通過する過程で、一次転写ローラ６２を介してバイアス電源７８から中間転写ベルト７７に印加される一次転写バイアスによって形成される電界により、中間転写ベルト７７の外周面に順次転写（一次転写）されていく。
【０２１０】
中間転写ベルト７７に対応する第１色のイエロートナー画像の転写を終えた感光ドラム５１の表面は、イエロー現像器７１のトナー担持体による現像兼クリーニング方式によりクリーニングされる。
【０２１１】
以下、同様に第２色のマゼンタトナー画像、第３色のシアントナー画像、第４色のブラックトナー画像が順次中間転写ベルト７７上に重ね合わせて転写され、目的のカラー画像に対応した合成カラートナー画像が形成される。
【０２１２】
６３は二次転写ローラで、二次転写対向ローラ６４に対応し平行に軸受させて中間転写ベルト７７の下面部に離間可能な状態に配設してある。
【０２１３】
トナー画像を感光ドラム５１から中間転写ベルト７７へ転写するための一次転写バイアスは、トナーとは逆極性でバイアス電源７８から印加される。その印加電圧は例えば＋１００Ｖ〜＋２ｋＶの範囲である。
【０２１４】
感光ドラム５１から中間転写ベルト７７への第１〜第３色のトナー画像の一次転写工程において、二次転写ローラ６３及びクリーニング装置５４は中間転写ベルト７７から離間することも可能である。
【０２１５】
中間転写ベルト７７上に転写されたフルカラー画像は、二次転写ローラ６３が中間転写ベルト７７に当接され、給紙ローラ８０から中間転写ベルト７０と二次転写ローラ６３との当接部分に所定のタイミングで第２の画像担持体である転写材Ｐが給送され、二次転写バイアスがバイアス電源７６から二次転写ローラ６３に印加されることにより転写材Ｐに二次転写される。トナー画像が転写された転写材Ｐは、定着器７５へ導入され加熱定着される。
【０２１６】
転写材Ｐへの画像転写終了後、中間転写ベルト７７には転写残余のトナーのクリーニング装置５４が当接され、中間転写ベルト７７がクリーニングされる。
【０２１７】
ところで、本発明は、感光体表面に離型性を付与することが好ましく、感光体表面の水に対する接触角は８５度以上であることが好ましい。この効果により、転写残余のトナー量を著しく減少させることができ、転写残余のトナーによる遮光がほとんどなくネガゴースト画像を本質的に防止できると共に現像時に転写残余のトナーの現像域での回収効率も向上し、ポジゴースト画像を防止する。
【０２１８】
ここで、ゴースト画像の発生メカニズムを説明する。
【０２１９】
転写残余のトナーによる遮光が特に問題となるのは、一枚の転写材に対し感光体表面が繰り返し使用される場合、つまり感光体一周分の長さが転写材の進行方向長さよりも短い場合、転写残余のトナーが感光体上に存在する状態で帯電と露光と現像をしなければならないため、転写残余のトナーの存在する感光体表面部での電位が充分落ちきらず現像コントラストが不十分になるため反転現像については周囲よりも濃度が低い、ネガゴーストとして画像上に現れる。
【０２２０】
一方、現像時に転写残余のトナーのクリーニング効果が不十分であれば、転写残余のトナーの存在する感光体表面上に、トナーが現像されるため周囲よりも濃度が高く、ポジゴーストが発生する。
【０２２１】
本発明の構成では上記の如きゴースト画像を本質的に防止することが出来る。
【０２２２】
また、本発明は感光体表面が高分子結着剤を主体として構成される場合に有効である。例えば、セレン、アモルファスシリコンなどの無機感光体の上に、樹脂を主体とした保護膜を設ける場合、又は機能分離型有機感光体の電荷輸送層として、電荷輸送材と樹脂からなる表面層をもつ場合、さらにその上に上記のような保護層を設ける場合等がある。このような表面層に離型性を付与する手段としては、
▲１▼膜を構成する樹脂自体に表面エネルギーの低いものを用いる、
▲２▼撥水、親油性を付与するような添加剤を加える、
▲３▼高い離型性を有する材料を粉体状にして分散する、
などが挙げられる。▲１▼の例としては、樹脂の構造中にフッ素含有基、シリコーン含有基等を導入することにより達成する。▲２▼としては、界面活性剤等を添加剤とすればよい。▲３▼としては、フッ素原子を含む化合物、すなわちポリ４フッ化エチレン、ポリフッ化ビニリデン、フッ化カーボン等が挙げられる。
【０２２３】
これらの手段によって感光体表面の水に対する接触角を８５度以上とすることができる。８５度未満では耐久によるトナーおよびトナー担持体の劣化が生じやすい。また、感光体表面の水に対する接触角は９０度以上とすることが、より好ましい。
【０２２４】
この中でも特にポリ４フッ化エチレンが好適である。本発明においては、▲３▼の含フッ素樹脂などの離型性粉体の最表面層への分散が好適である。
【０２２５】
これらの粉体を表面に含有させるためには、バインダー樹脂中に該粉体を分散させた層を感光体最表面に設けるか、あるいは、元々樹脂を主体として構成されている有機感光体であれば、新たに表面層を設けなくても、最上層に該粉体を分散させれば良い。
【０２２６】
該粉体の表面層への添加量は、表面層の総重量に対して、１〜６０重量％、さらには２〜５０重量％が好ましい。１重量％より少ないと転写残余のトナーが充分に減少せず、転写残余のトナーのクリーニング効率も充分でなく、ゴースト防止効果が不十分であり、６０重量％を超えると膜の強度が低下したり、感光体への入射光量が著しく低下したりするため、好ましくない。また、該粉体の粒径については、画質の面から、１μｍ以下、好ましくは０．５μｍ以下が望ましい。１μｍより大きいと入射光の散乱によりラインの切れが悪くなり実用に耐えない。
【０２２７】
本発明は、帯電手段が帯電部材を感光体に当接させる直接帯電法の場合に特に効果的である。すなわち、クリーニング後の未回収トナーが多いと、それが後工程である直接帯電部材に付着してしまい、帯電不良を引き起こす。従って、帯電手段が感光体に接することのないコロナ放電等に比べて、未回収トナーの量はより少なく、付着し難くする必要がある。
【０２２８】
本発明に用いられる感光体の好ましい様態のひとつを以下に説明する。
【０２２９】
導電性基体としては、アルミニウム・ステンレス等の金属、アルミニウム合金・酸化インジウム−酸化錫合金等による被膜層を有するプラスチック、導電性粒子を含侵させた紙・プラスチック、導電性ポリマーを有するプラスチック等の円筒状シリンダー及びフィルムが用いられる。
【０２３０】
これら導電性基体上には、感光層の接着性向上・塗工性改良・基体の保護・基体上に欠陥の被覆・基体からの電荷注入性改良・感光層の電気的破壊に対する保護等を目的として下引き層を設けても良い。下引き層は、ポリビニルアルコール・ポリ−Ｎ−ビニルイミダゾール・ポリエチレンオキシド・エチルセルロース・メチルセルロース・ニトロセルロース・エチレン−アクリル酸コポリマー・ポリビニルブチラール・フェノール樹脂・カゼイン・ポリアミド・共重合ナイロン・ニカワ・ゼラチン・ポリウレタン・酸化アルミニウム等の材料によって形成される。その膜厚は通常０．１〜１０μｍ、好ましくは０．１〜３μｍ程度である。
【０２３１】
電荷発生層は、アゾ系顔料・フタロシアニン系顔料・インジゴ系顔料・ペリレン系顔料・多環キノン系顔料・スクワリリウム色素・ピリリウム塩類・チオピリリウム塩類・トリフェニルメタン系色素、セレン・非晶質シリコン等の無機物質などの電荷発生物質を適当な結着剤に分散し塗工するあるいは蒸着等により形成される。なかでもフタロシアニン系顔料が感光体感度を本発明に適合する感度に調整するうえで好ましい。結着剤としては、広範囲な結着性樹脂から選択でき、例えば、ポリカーボネート樹脂・ポリエステル樹脂・ポリビニルブチラール樹脂・ポリスチレン樹脂・アクリル樹脂・メタクリル樹脂・フェノール樹脂・シリコーン樹脂・エポキシ樹脂・酢酸ビニル樹脂等が挙げられる。電荷発生層中に含有される結着剤の量は８０重量％以下、好ましくは０〜４０重量％に選ぶ。また、電荷発生層の膜厚は５μｍ以下、特には０．０５〜２μｍが好ましい。
【０２３２】
電荷輸送層は、電界の存在下で電荷発生層から電荷キャリアを受け取り、これを輸送する機能を有している。電荷輸送層は電荷輸送物質を必要に応じて結着樹脂と共に溶剤中に溶解し、塗工することによって形成され、その膜厚は一般的には５〜４０μｍである。電荷輸送物質としては、主鎖または側鎖にビフェニレン・アントラセン・ピレン・フェナントレンなどの構造を有する多環芳香族化合物、インドール・カルバゾール・オキサジアゾール・ピラゾリンなどの含窒素環式化合物、ヒドラゾン化合物、スチリル化合物、セレン・セレン−テルル・非晶質シリコン・硫化カドニウム等が挙げられる。
【０２３３】
これら電荷輸送物質を分散させる結着樹脂としては、ポリカーボネート樹脂・ポリエステル樹脂・ポリメタクリル酸エステル・ポリスチレン樹脂・アクリル樹脂・ポリアミド樹脂等の樹脂、ポリ−Ｎ−ビニルカルバゾール・ポリビニルアントラセン等の有機光導電性ポリマー等が挙げられる。
【０２３４】
また、表面層として、保護層を設けてもよい。保護層の樹脂としては、ポリエステル・ポリカーボネート・アクリル樹脂・エポキシ樹脂・フェノール樹脂、あるいはこれらの樹脂の硬化剤等が単独あるいは２種以上組み合わされて用いられる。
【０２３５】
また、保護層の樹脂中に導電性微粒子を分散してもよい。導電性微粒子の例としては、金属・金属酸化物等が挙げられ、好ましくは、酸化亜鉛・酸化チタン・酸化スズ・酸化アンチモン・酸化インジウム・酸化ビスマス・酸化スズ被膜酸化チタン・スズ被膜酸化インジウム・アンチモン被膜酸化スズ・酸化ジルコニウム等の超微粒子がある。これらは単独で用いても２種以上を混合して用いても良い。一般的に保護層に粒子を分散させる場合、分散粒子による入射光の散乱を防ぐために入射光の波長よりも粒子の粒径の方が小さいことが必要であり、本発明における保護層に分散される導電性、絶縁性粒子の粒径としては０．５μｍ以下であることが好ましい。また、保護層中での含有量は、保護層総重量に対して２〜９０重量％が好ましく、５〜８０重量％がより好ましい。保護層の膜厚は、０．１〜１０μｍが好ましく、１〜７μｍがより好ましい。
【０２３６】
表面層の塗工は、樹脂分散液をスプレーコーティング、ビームコーティングあるいは浸透（ディッピング）コーティングすることによって行うことができる。
【０２３７】
本発明に用いられる現像工程は、現像剤と感光体表面が接触しており、特に反転現像方法を用いる場合に非常に好適である。二成分磁気ブラシ現像方法を用いる場合は、そのキャリアとして、フェライト、マグネタイト、鉄粉あるいは、それらをアクリル樹脂、シリコーン樹脂、フッ素樹脂等でコーティングしたものが用いられる。このとき、現像時あるいは現像前後の空白時には、直流あるいは交流成分のバイアスを印加し、現像と感光体上の残余のトナーを回収出来るような電位に制御される。このとき直流成分は、明部電位と暗部電位の間に位置する。
【０２３８】
一成分現像剤の場合、トナー担持体として弾性ローラーを用い、弾性ローラー表面等にトナーをコーティングしこれを感光体表面と接触させる方法も用いられる。このとき、トナーの磁性、非磁性は問わず、ただ、トナーと感光体表面が接触していることが重要となる。このとき、トナーを介して、感光体と感光体表面に対向する弾性ローラー間に働く電界によって現像と共にクリーニングが行われるので、弾性ローラ表面あるいは、表面近傍が電位をもち、感光体表面とトナー担持表面間で電界を有する必要性がある。このため、弾性ローラーの弾性ゴムが中抵抗領域に抵抗制御されて感光体表面との導通を防ぎつつ電界を保つか、または導電性ローラーの表面層に薄層の絶縁層を設ける方法も利用できる。さらには、導電性ローラ上に感光体表面に対向する側を絶縁性物質により被覆した導電性樹脂スリーブあるいは、絶縁性スリーブで感光体に対向しない側に導電層を設けた構成も可能である。また、トナー担持体として剛体ローラを用い、感光体をベルトのごときフレキシブルなものとした構成も可能である。トナー担持体としての現像ローラの抵抗としては１０²〜１０⁹Ω・ｃｍの範囲が好ましい。
【０２３９】
一成分接触現像法を用いた場合そのトナーを担持するローラー表面と感光体の周速同方向に回転していてもよいし、逆方向に回転していてもよい。その回転が同方向である場合感光体の周速に対して、周速比で１００％以上が望ましい。１００％未満であると、画像品質が悪い。周速比が高まれば高まるほど、現像部位に供給されるトナーの量は多く、潜像に対しトナーの脱着頻度が多くなり、不要な部分は掻き落とされ必要な部分には付与されるという繰り返しにより、潜像に忠実な画像が得られる。現像兼クリーニングという観点では、感光体上に密着した転写残余のトナーを感光体表面とトナーの付着部分を周速差により物理的に引き剥がし電界により回収すると言う効果も期待できることから、周速比は高いほど転写残余のトナーの回収には都合がよい。具体的には、トナー担持体面の移動速度が感光体面の移動速度に対し、１．０５〜３．０倍の速度であることが好ましい。
【０２４０】
以下、本発明の画像形成方法に適用可能な接触転写工程について具体的に説明する。
【０２４１】
接触転写工程とは、感光体と転写材を介して転写手段を当接しながら現像画像を転写材に静電転写するものであるが、転写手段の当接圧力としては線圧２．９Ｎ／ｍ（３ｇ／ｃｍ）以上であることが好ましく、より好ましくは１９．６Ｎ／ｍ（２０ｇ／ｃｍ）以上である。当接圧力としての線圧が２．９Ｎ／ｍ（３ｇ／ｃｍ）未満であると、転写材の搬送ずれや転写不良の発生が起こりやすくなるため好ましくない。
【０２４２】
また、接触転写工程における転写手段としては、転写ローラーあるいは転写ベルトを有する装置が使用される。転写ローラーは少なくとも芯金と導電性弾性層からなり、導電性弾性層はカーボン等の導電材を分散させたウレタンやＥＰＤＭ等の、体積抵抗１０⁹〜１０¹⁰Ωｃｍ程度の弾性体で作られている。
【０２４３】
本発明は、感光体の表面が有機化合物である様な画像形成装置において特に有効に用いられる。即ち、有機化合物が感光体の表面層を形成している場合には、無機材料を用いた他の感光体よりもトナー粒子に含まれる結着樹脂との接着性に優れ、転写性がより低下する傾向にあるためである。
【０２４４】
また、本発明に係わる感光体の表面物質としては、たとえばシリコーン樹脂、塩化ビニリデン、エチレン−塩化ビニル、スチレン−アクリロニトリル、スチレン−メチルメタクリレート、スチレン、ポリエチレンテレフタレートおよびポリカーボネート等が挙げられるが、これらに限定されることはなく他のモノマーあるいは前述の結着樹脂間での共重合体およびブレンド体等も使用することができる。
【０２４５】
また、本発明は、直径が５０ｍｍ以下の小径の感光体を有する画像形成装置に対し特に有効に用いられる。即ち、小径感光体の場合には、同一の線圧に対する曲率が大きく、当接部における圧力の集中が起こりやすいためである。ベルト感光体でも同一の現象があると考えられるが、本発明は、転写部での曲率半径が２５ｍｍ以下の画像形成装置に対しても有効である。
【０２４６】
さらに本発明に係るトナーは、高い帯電能力を有するために現像に際しては、トナーの総帯電量をコントロールすることが望ましく、本発明に係わるトナー担持体の表面は導電性微粒子及び／又は滑剤を分散した樹脂層で被覆されていることが好ましい。
【０２４７】
帯電方法としては、コロトロンあるいはスコロトロンなどと呼ばれる公知のコロナ帯電方法が用いられるほか、ピン電極を用いた方法等も使用できる。また、直接帯電法も同様に使用できる。
【０２４８】
さらに、本発明においてはオゾンが発生しないように帯電部材が感光体に当接されていることが環境保全上好ましい。
【０２４９】
帯電ローラーを用いたときの好ましいプロセス条件としては、ローラーの当接圧が５〜５００ｇ／ｃｍで、転写残余のトナーの極性を感光体の帯電極性と同じ極性に揃え、現像時での回収を容易にするため、直流電圧の印加がよいが、直流電圧に交流電圧を重畳したものを用いたときには、２×Ｖｔｈ（Ｖ）［Ｖｔｈ；直流印加における放電開始電圧（Ｖ）］未満のピーク間電圧を有する交流電圧を直流電圧に重畳することが好ましい。
【０２５０】
この他の帯電手段としては、帯電ブレードを用いる方法や、導電性ブラシを用いる方法がある。これらの接触帯電手段は、高電圧が不要になったり、オゾンの発生が低減するといった効果がある。
【０２５１】
接触帯電部材としては、ローラーまたはブレードの場合は、導電性基体として、鉄、銅、ステンレス等の金属、カーボン分散樹脂、金属あるいは金属酸化物分散樹脂などが用いられ、その形状としては棒状、板状等が使用できる。例えば、弾性ローラーの構成としては、導電性基体上に弾性層、導電層、抵抗層を設けたものが用いられ、ローラー弾性層としては、クロロプレンゴム、イソプレンゴム、ＥＰＤＭゴム、ポリウレタンゴム、エポキシゴム、ブチルゴムなどのゴム又はスポンジや、スチレン−ブタジエンサーモプラスチックエラストマー、ポリウレタン系サーモプラスチックエラストマー、ポリエステル系サーモプラスチックエラストマー、エチレン−酢ビサーモプラスチックエラストマー等のサーモプラスチックエラストマーなどで形成することができ、導電層としては、体積抵抗率を１０⁷Ω・ｃｍ以下、望ましくは１０⁶Ω・ｃｍ以下である。例えば、金属蒸着膜、導電性粒子分散樹脂、導電性樹脂等が用いられ、具体例としては、アルミニウム、インジウム、ニッケル、銅、鉄等の蒸着膜、導電性粒子分散樹脂の例としては、カーボン、アルミニウム、ニッケル、酸化チタンなどの導電性粒子をウレタン、ポリエステル、酢酸ビニル−塩化ビニル共重合体、ポリメタクリル酸メチル等の樹脂中に分散したものなどが挙げられる。導電性樹脂としては、４級アンモニウム塩含有ポリメタクリル酸メチル、ポリビニルアニリン、ポリビニルピロール、ポリジアセチレン、ポリエチレンイミンなどが挙げられる。抵抗層は、例えば、体積抵抗率が１０⁶〜１０¹²Ω・ｃｍの層であり、半導性樹脂、導電性粒子分散絶縁樹脂等を用いることができる。半導性樹脂としては、エチルセルロース、ニトロセルロース、メトキシメチル化ナイロン、エトキシメチル化ナイロン、共重合ナイロン、ポリビニルヒドリン、カゼイン等の樹脂が用いられる。導電性粒子分散樹脂の例としては、カーボン、アルミニウム、酸化インジウム、酸化チタンなどの導電性粒子をウレタン、ポリエステル、酢酸ビニル−塩化ビニル共重合体、ポリメタクリル酸メチル等の絶縁性樹脂中に少量分散したものなどが挙げられる。
【０２５２】
帯電部材としてのブラシは、一般に用いられている繊維に導電材を分散させて抵抗調整されたものが用いられる。繊維としては、一般に知られている繊維が使用可能であり、例えばナイロン、アクリル、レーヨン、ポリカーボネート、ポリエステル等が挙げられる。また導電材としては、これも一般に知られている導電材が使用可能であり、銅、ニッケル、鉄、アルミニウム、金、銀等の金属あるいは酸化鉄、酸化亜鉛、酸化スズ、酸化アンチモン、酸化チタン等の金属酸化物、さらにはカーボンブラック等の導電粉が挙げられる。なおこれら導電粉は必要に応じ疎水化、抵抗調整の目的で表面処理が施されていてもよい。使用に際しては、繊維との分散性や生産性を考慮して選択して用いる。ブラシの形状としては、繊維の太さが１〜２０デニール（繊維径１０〜５００μｍ程度）、ブラシの繊維の長さは１〜１５ｍｍ、ブラシ密度は１平方インチ当たり１万〜３０万本（１平方メートル当り１．５×１０⁷〜４．５×１０⁸本程度）のものが好ましく用いられる。
【０２５３】
【実施例】
以下、具体的実施例によって本発明を説明するが、本発明はなんらこれらに限定されるものではない。
【０２５４】
本発明に用いられるワックス成分の内容をＤＳＣの測定結果と共に表１にまとめる。
【０２５５】
【表１】

【０２５６】
すなわち、＜Ａ＞高級脂肪酸エステルワックス、＜Ｂ＞高級アルコールワックス、＜Ｃ＞フィッシャートロプシュ法により合成したポリアルキレンから分別により得られたワックス、＜Ｄ＞アーゲ法により合成したポリアルキレンから分別により得られたワックス、＜Ｅ＞ポリプロピレンの酸化分解より得られたワックス（以上、本発明のトナー用）、及び＜ａ＞と＜ｂ＞ポリエチレンの酸化分解より得られたワックス（比較トナー用）である。
【０２５７】
［トナーの製造例及び比較製造例］
本発明のトナーの製造例及び比較製造例について述べる。
【０２５８】
トナーの製造例１
高速撹拌装置ＴＫ式ホモミキサー（特殊機化工業社製）を備えた２リットル用４つ口フラスコ中にイオン交換水６５０ｇと０．１ｍｏｌ／リットル−Ｎａ₃ＰＯ₄水溶液５００ｇを投入し、回転数を１２０００ｒｐｍに調整し、７０℃に加温せしめた。ここに１．０ｍｏｌ／リットル−ＣａＣｌ₂水溶液７０重量部を徐々に添加し、微小な難水溶性分散安定剤Ｃａ₃（ＰＯ₄）₂を含む水系分散媒体を調製した。
【０２５９】
一方、分散質として、
・スチレン ７７重量部
・２−エチルヘキシルアクリレート ２３重量部
・ジビニルベンゼン ０．２重量部
・カーボンブラック（粒径＝４５ｎｍ） ８重量部
・ポリカーボネート樹脂（ピーク分子量＝７０００） ５重量部
・アゾ系鉄錯体化合物（Ａ−１） ２重量部
・前記表１のワックス成分＜Ａ＞ １０重量部
からなる混合物をアトライター（三井金属社製）を用い３時間分散させた後、２，２’−アゾビス（２，４−ジメチルバレロニトリル）１０重量部を添加し重合性単量体組成物を調製した。
【０２６０】
次に、前記水系分散媒体中に該重合性単量体組成物を投入し、内温７０℃のＮ₂雰囲気下で、高速撹拌器の回転数を１２０００ｒｐｍに維持しつつ、１５分間撹拌し、該重合性単量体組成物を造粒した。その後、撹拌器をプロペラ撹拌羽根に換え５０ｒｐｍで撹拌しながら同温度に５時間保持し、更に８０℃に昇温して１０時間保持して重合を完了した。
【０２６１】
重合終了後、８０℃／４７ｋＰａ（３５０Ｔｏｒｒ）の加熱減圧下で残存モノマーを留去し、懸濁液を冷却し、次いで希塩酸を添加し分散安定剤を除去せしめた。更に水洗浄を数回繰り返した後、円錘型リボン乾燥機（大川原製作所製）を用い、４５℃／１．３ｋＰａ（１０Ｔｏｒｒ）の加熱減圧下で、螺旋リボン回転翼で撹拌しながら重合体粒子の球形化処理と乾燥処理を６時間行い、重合体粒子（Ａ）を得た。
【０２６２】
該重合体粒子（Ａ）は、円相当個数平均径が３．７μｍで、円形度頻度分布における平均円形度が０．９８５で、円形度標準偏差が０．０３０で、ＧＰＣによる分子量分布で、ピーク分子量が１．２万、Ｍｗ／Ｍｎが１３であった。
【０２６３】
また、該重合体粒子（Ａ）に残存する揮発成分は、スチレンモノマーが４０ｐｐｍ、２−エチルヘキシルアクリレートモノマーが０ｐｐｍ（検出されず）であった。更に、ワックス成分の分散状態をＴＥＭで観察したところ、図６（ａ）の模式図の様に結着樹脂中に実質的に球状を呈し分散していた。
【０２６４】
上記重合体粒子（Ａ）１００重量部と疎水性オイル処理シリカ微粉体（ＢＥＴ；２００ｍ²／ｇ）２重量部をヘンシェルミキサー（三井金属社製）で乾式混合して、本発明のトナー（Ａ）とした後、該トナー（Ａ）５重量部と樹脂コート磁性フェライトキャリア（平均粒径；４０μｍ）９５重量部とを混合して磁気ブラシ現像用二成分系現像剤（Ａ）を調製した。
【０２６５】
トナーの製造例２〜５
ワックス成分の種類及び添加量、極性樹脂の種類及び添加量を変えると共に、残存モノマーの留去時の温度と減圧度と処理時間、円錐型リボン乾燥機の設定温度と撹拌条件と処理時間を変更することにより、粒子の粒度分布と形状、及び残存モノマー量をコントロールした以外は前記のトナーの製造例１と同様にして、重合体粒子（Ｂ）〜（Ｅ）を得た後、本発明のトナー（Ｂ）〜（Ｅ）、現像剤（Ｂ）〜（Ｅ）を調製した。
【０２６６】
それぞれの製造例におけるワックスの種類及び添加量、極性樹脂の種類及び添加量は、表２に示す。
【０２６７】
トナーの比較製造例１
ワックス成分＜Ａ＞とポリカーボネート樹脂に代え、前記表１のワックス成分＜ａ＞と飽和ポリエステル樹脂（プロポキシ化ビスフェノールＡとテレフタル酸の縮合重合体、ピーク分子量＝７０００）を用いる以外は、トナーの製造例１と同様にして比較用重合体粒子（ａ）を得た後、比較用トナー（ａ）、更には、比較用現像剤（ａ）を調製した。
【０２６８】

【０２６９】
上記混合物を二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕物をジェットミルで微粉砕し、得られた微粉砕物を分級して分級粉（ｂ）とした。該分級粉（ｂ）を用い前記トナーの製造例１と同様にして比較用トナー（ｂ）、更には、比較用現像剤（ｂ）を調製した。
【０２７０】
なお、分級粉（ｂ）中には、揮発成分として結着樹脂に由来するスチレンモノマーが１８２ｐｐｍ、２−エチルヘキシルアクリレートモノマー６ｐｐｍが残留し、また、ワックス成分は微分散していた。
【０２７１】
上記で得られた重合体粒子（Ａ）〜（Ｅ）、比較用重合体粒子（ａ）、及び、分級粉（ｂ）の諸性状を表２にまとめる。
【０２７２】
【表２】

【０２７３】
トナーの製造例６
・スチレン ７５重量部
・２−エチルヘキシルアクリレート ２５重量部
・ジビニルベンゼン ０．３重量部
・ポリカーボネート樹脂（ピーク分子量＝３０００） ５重量部
・ジルコニウム化合物（Ｂ−１５） ２重量部
・前記表１のワックス成分＜Ｃ＞ １０重量部
上記混合物からなる重合性単量体組成物を分散質とする以外は、前記のトナー製造例１と同様にして、重合体粒子（Ｆ）を得た。
【０２７４】
上記重合体粒子（Ｆ）１００重量部と、疎水性オイル処理シリカ微粉体（ＢＥＴ：５０ｍ²／ｇ）１．５重量部と、疎水性オイル処理酸化チタン微粉体（ＢＥＴ：２００ｍ²／ｇ）０．５重量部を、ヘンシェルミキサー（三井金属社製）で乾式混合して、本発明のトナー（Ｆ）とした。
【０２７５】
トナーの製造例７〜９、並びに、比較製造例３〜６
着色剤、ジルコニウム化合物、及び、極性樹脂の種類と添加量を変更すると共に、残存モノマーの留去時の温度と減圧度と処理時間、円錐型リボン乾燥機の設定温度と撹拌条件と処理時間を変更する以外は前記のトナーの製造例１と同様にして、重合体粒子（Ｇ）〜（Ｉ）、及び、比較用重合体粒子（ｃ）〜（ｆ）を得た後、本発明のトナー（Ｇ）〜（Ｉ）及び、比較用トナー（ｃ）〜（ｆ）を調製した。
【０２７６】
それぞれの製造例における着色剤、ジルコニウム化合物、極性樹脂の種類と添加量及び、得られた重合体粒子（Ｆ）〜（Ｉ）、比較用重合体粒子（ｃ）〜（ｆ）の諸性状を表３にまとめる。
【０２７７】
【表３】

【０２７８】
［静電潜像担持体の製造例］
本発明の画像形成方法に用いられる静電潜像担持体として感光体ドラムの製造例について述べる。
【０２７９】
感光体ドラムの製造例１
直径３０ｍｍ，長さ２５４ｍｍのアルミニウムシリンダーを基体とし、次に示すような構成の層を順次浸漬塗布により積層して、感光体ドラム１を作製した。
【０２８０】
（１）導電性被覆層：酸化錫及び酸化チタンの粉未をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
【０２８１】
（２）下引き層：変性ナイロン及び共重合ナイロンを主体とする。膜厚０．６μｍ。
【０２８２】
（３）電荷発生層：長波長域に吸収を持つアゾ顔料をブチラール樹脂に分散したものを主体とする。膜厚０．６μｍ。
【０２８３】
（４）電荷輸送層：ホール搬送性トリフェニルアミン化合物をポリカーボネート樹脂（オストワルド粘度法による分子量２万）に８：１０の重量比で溶解したものを主体とし、さらにポリ４フッ化エチレン粉体（粒径０．２μｍ）を総固形分に対して１０重量％添加し、均一に分散した。膜厚２５μｍ。
【０２８４】
得られた感光体ドラム１の表面の水に対する接触角は９５度であった。
【０２８５】
なお、接触角の測定は、純水を用い、装置は、協和界面科学（株）、接触角計ＣＡ−ＤＳ型を用いた。
【０２８６】
感光体ドラムの製造例２
電荷輸送層にポリ４フッ化エチレン粉体を添加しなかったことを除いては、感光体ドラムの製造例１と同様にして膜厚２５μｍの電荷輸送層を形成し、感光体ドラム２を作製した。得られた感光体ドラム２の表面の水に対する接触角は７９度であった。
【０２８７】
実施例１
図１と図２に示す二成分現像プロセスを有する画像形成装置を用いて画像形成を行った。
【０２８８】
静電潜像担持体２の表面は１８０ｍｍ／ｓｅｃの回転周速で移動するように設定し、現像剤は現像剤（Ａ）を用いた。
【０２８９】
トナーを補給しつつ１０００枚のプリントアウト試験を行い、画像評価を行ったところ、画像濃度やドット再現性は共に良好であり、画像汚れ、カブリ、飛び散り、中抜け等の画像不良も発生せず、高品位な画像が得られた。また、感光体と現像ローラーの表面を観察したが融着や傷もなく、帯電ローラーへのトナーの付着量も軽微であり、交換することを必要としなかった。
【０２９０】
評価結果を表４に示す。
【０２９１】
実施例２、参考例３〜５
現像剤として現像剤（Ｂ）〜（Ｅ）を使用することを除いては実施例１と同様にして評価した。結果は表４に示すように概ね良好であった。
【０２９２】
比較例１及び２
現像剤として比較用現像剤（ａ）と（ｂ）を使用することを除いては実施例１と同様にして評価した。結果は表４に示すように帯電部材をトナーが著しく汚染し、帯電不良による画像不良を招いた。
【０２９３】
【表４】

【０２９４】
実施例６
図３は本実施例に適用される一成分現像プロセスを有する画像形成装置の断面の概略的説明図であり、市販のレーザープリンターＬＢＰ−ＥＸ（キヤノン社製）を改造し、再設定して用いた。即ち、静電潜像担持体３６の表面は９６ｍｍ／ｓｅｃの回転周速（１６枚（Ａ４サイズ）／分のプリントアウト速度に相当）で矢印の方向に移動する。プロセスカートリッジにおけるクリーニングゴムブレードを取りはずし、装置の帯電方式をゴムローラー３１を当接する接触帯電であり、印加電圧を直流成分（−１４００Ｖ）とした。レーザー光４０で露光（６００ｄｐｉ）することにより静電潜像を形成した。
【０２９５】
次に、プロセスカートリッジにおける現像部分を改造した。トナー担持体であるステンレススリーブの代わりに発泡ウレタンからなる中抵抗ゴムローラー（１６ｍｍ、硬度ＡＳＫＥＲ Ｃ４５度、抵抗１０⁵Ω・ｃｍ）を用いて、静電潜像担持体３６に当接させた。該トナー担持体３４表面の移動方向は、感光体表面の移動方向と同方向であり、該感光体回転周速に対し１３０％となるように駆動する。
【０２９６】
トナー担持体３４にトナーを塗布する手段として、現像部分に塗布ローラー３５を、トナー担持体３４に当接させて設けた。さらに、トナー担持体３４上トナーのコート層制御のために、樹脂をコートしたステンレス製ブレード３３を取付けた。
【０２９７】
静電潜像担持体３６としては、感光体ドラムの製造例１で作製した感光体（１）を用い、トナーはトナー（Ａ）を用い、以下の現像条件を満足するようにプロセス条件を設定した。
感光体暗部電位：−８００Ｖ
感光体明部電位：−１５０Ｖ
現像バイアス：−４５０Ｖ（直流成分のみ）
【０２９８】
トナーを補給しつつ１０００枚のプリントアウトを行い画像評価を行ったところ、画像濃度やドット再現性は共に良好であり、画像汚れ、カブリ、飛び散り、中抜け、ゴーストなどの画像不良も発生せず、初期と同等の画像品質を得た。また、感光体と現像ローラー表面を観察したが、融着や傷もなく、帯電ローラーへのトナー付着量も軽微であり、交換することを必要としなかった。
【０２９９】
評価結果を表５に示す。
【０３００】
実施例７
実施例６で用いた画像形成装置の静電潜像担持体３６の表面の回転周速を１４４ｍｍ／ｓｅｃ（２０枚（Ａ４サイズ）／分のプリントアウト速度に相当）とし、現像容器３２中のトナー塗布ローラー３５として単層構造のスポンジローラーを用い、このトナー塗布ローラー３５に図示されていないバイアス印加手段からバイアス電圧を印加するように変更することを除いては、実施例６と同様にして画像形成を行ない評価を行なった。
【０３０１】
この現像時の現像ローラー３４には現像バイアス電圧として直流成分のみを−３００Ｖ、また、トナー塗布ローラー３５にはバイアス電圧として直流成分のみを−４５０Ｖ印加した。
【０３０２】
プリントアウト速度を速めている分、感光体の均一な帯電やトナーの帯電量制御、更には、帯電ローラーへのトナー汚染に対し厳しい条件となっているにもかかわらず優れた画像が得られた。また、帯電ローラーへのトナー付着量が増えたものの画像形成装置とのマッチングも概ね良好であった。
【０３０３】
実施例８
感光体ドラムの製造例２で作製した感光体（２）を使用することを除いては実施例６と同様にしてプリントアウト試験を行った。得られた画像には軽微なゴーストを生じ結果は表５に示すように実施例６と比較するとやや劣るものの、概ね良好であった。
【０３０４】
実施例９、参考例１０〜１２
トナーとしてトナー（Ｂ）〜（Ｅ）を使用することを除いては実施例６と同様にしてプリントアウト試験を行った。結果は表５に示すように、概ね良好であった。
【０３０５】
比較例３及び４
トナーとして比較用トナー（ａ）と（ｂ）を使用することを除いては実施例６と同様にして評価した。結果は表５に示すように帯電部材をトナーが著しく汚染し、帯電不良による画像不良を招いた。
【０３０６】
【表５】

【０３０７】
実施例１３
図４に示す転写ベルトを有する画像形成装置を用いて画像形成を行った。
【０３０８】
画像形成装置には、第１のクリーニング手段としてトナー担持体により現像兼クリーニング方式が行われ、第２の転写工程後、中間転写体表面に残存するトナーを除去するためのクリーニング手段として、中間転写体表面に当接するクリーニング部材を有するクリーナーが、第２の転写部より下流側であり、第１の転写部よりも上流側に設けられている。
【０３０９】
現像器５７としては、図３に示す現像器３２の構成のものを用いた。第１の転写後感光体ドラム表面に残存するトナーは、帯電部で帯電バイアスの印加により、トナーの帯電極性を負極性にそろえた後、現像時に現像部で非画像領域に存在するトナーのみ現像器中で回収させる構成にした。
【０３１０】
現像器８において、カーボンブラックを分散して抵抗を調整したシリコーンゴムからなる中抵抗ゴムローラ（１６ｍｍ）をトナー担持体９とし、感光体に当接した。トナー担持体９の表面の移動方向及び回転周速は、感光体表面との接触部分において同方向であり、該感光体回転周速に対し１５０％となるように駆動する。つまり、トナー担持体の周速は１２０ｍｍ／ｓであり、感光体表面に対する相対速度は８０ｍｍ／ｓである。
【０３１１】
トナー担持体にトナーを塗布する手段として、単層構成のスポンジローラーを塗布ローラー１２として設け、該トナー担持体に当接させた。接触部において、塗布ローラー１２の表面の移動方向が、トナー担持体の移動方向と反対方向に移動するように回転させることによりトナーをトナー担持体上に塗布した。さらに、該トナー担持体上トナーのコート層制御のために、樹脂をコートしたステンレス製ブレード１６を取付けた。
【０３１２】
感光体としては、感光体製造例１で製造した感光体（１）を用い、トナーはトナー（Ａ）を用い、以下の現像条件及び転写条件を満足するよう画像形成条件を設定した。
感光体暗部電位：−７００Ｖ
感光体明部電位：−１５０Ｖ
現像ローラーに印加する現像バイアス ：−４５０Ｖ（直流成分のみ）
トナー塗布ローラーに印加するバイアス：−３００Ｖ（直流成分のみ）
第１の転写工程で中間転写体に印加する転写バイアス：３５０Ｖ（直流成分のみ）
第２の転写工程で転写ローラーに印加する転写バイアス：１１００Ｖ（直流成分のみ）
【０３１３】
上記の画像形成条件によって、記録材上に転写されたトナー画像は、以下の加熱定着装置によって、転写材に加熱定着した。
【０３１４】
加熱定着装置７０にはオイル塗布機能のない熱ロール方式の定着装置を用いた。この時上部ローラー６８、下部ローラー６９共にフッ素系樹脂の表面層を有するものを使用し、ローラーの直径は５５ｍｍであった。また、定着温度は１５０℃、ニップ幅を７ｍｍに設定した。
【０３１５】
上記の構成の画像形成装置を用いてトナーを補給しつつ１０００枚のプリントアウト試験を行い画像評価を行ったところ、高濃度で画像汚れのない高品質の画像が得られた。
【０３１６】
参考例１４、実施例１５、参考例１６
トナーとしてトナー（Ｇ）〜（Ｈ）を使用することを除いては実施例１３と同様にしてプリントアウト試験を行った。結果は表６に示すように、概ね良好であった。
【０３１７】
比較例５〜８
トナーとして比較用トナー（ｃ）〜（ｆ）を使用することを除いては実施例１３と同様にしてプリントアウト試験を行った。結果は表６に示すように、帯電部材をトナーが著しく汚染し、帯電不良による画像不良を招いた。
【０３１８】
【表６】

【０３１９】
実施例１７
トナーとしてトナー（Ｆ）〜（Ｈ）を使用し、フルカラーの画像形成を試みたところ、良好な画像が得られた。
【０３２０】
比較例９
トナーとして比較用トナー（ｃ）〜（ｆ）を使用することを除いては実施例１７と同様にフルカラーの画像の形成を試みたが、著しい帯電不良が発生し途中で中止せざるを得なかった。
【０３２１】
実施例１８
図５に示す転写ベルトを有する画像形成装置を用いて画像形成を行った。
【０３２２】
即ち、実施例１３で用いた画像形成装置の第２のクリーニング手段である中間転写ベルト２０のクリーニング装置５０を取りはずし、代わりに帯電部材５２を当接し、感光ドラムとは逆極性のバイアスを印加することにより、転写材Ｐに転写されずに中間転写ベルトに残留している転写残トナーに感光ドラムと逆極性の電荷を付与し、該転写残トナーを感光ドラムとの当接部およびその近傍において感光ドラムに静電的に転写させることにより、中間転写ベルトがクリーニングされ、更に、感光ドラム上に転写された該転写残トナーをブラック色現像器４４を作動させ回収し、感光ドラムの表面を清掃するように設定した。
【０３２３】
トナーとしてトナー（Ｆ）〜（Ｈ）を使用し、フルカラーの画像形成を試みたところ、概ね良好な画像が得られた。
【０３２４】
比較例１０
トナーとして比較用トナー（ｃ）〜（ｆ）を使用することを除いては実施例１８と同様にフルカラーの画像形成を試みたが、帯電ローラーと中間転写ベルトへのトナー付着が著しく途中で中止せざるを得なかった。
【０３２５】
本発明の実施例及び比較例中に記載の評価項目の説明とその評価基準について述べる。
【０３２６】
［プリントアウト画像評価］
＜１＞画像濃度
通常の複写機用普通紙（７５ｇ／ｍ²）に所定の枚数のプリントアウトを終了した時の画像濃度により評価した。尚、画像濃度は「マクベス反射濃度計」（マクベス社製）を用いて、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
【０３２７】
Ａ：１．４０以上
Ｂ：１．３５以上、１．４０未満
Ｃ：１．００以上、１．３５未満
Ｄ：１．００未満
【０３２８】
＜２＞画像汚れ
帯電ローラーの周囲長の周期で画像上に現われる帯電不良に起因する画像汚れを目視により評価した。
【０３２９】
Ａ：ほとんど発生せず
Ｂ：軽微な画像汚れが見られる
Ｃ：若干の画像汚れが見られる
Ｄ：顕著な画像汚れが見られる
【０３３０】
＜３＞ドット再現性
潜像電界によって電界が閉じ易く、再現しにくい図８に示す様な小径（５０μｍ）の孤立ドットパターンの画像をプリントアウトし、そのドット再現性を評価した。
【０３３１】
Ａ：欠損２個以下／１００個
Ｂ：欠損３〜５個／１００個
Ｃ：欠損６〜１０個／１００個
Ｄ：欠損１１個以上／１００個
【０３３２】
＜４＞画像カブリ
「リフレクトメータ」（東京電色社製）により測定したプリントアウト画像の白地部分の白色度と転写紙の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価した。
【０３３３】
Ａ：１．５％未満
Ｂ：１．５％以上、２．５％未満
Ｃ：２．５％以上、４．０％未満
Ｄ：４．０％以上
【０３３４】
＜５＞画像飛び散り
図９（ａ）に示した「電」文字パターンを普通紙（７５ｇ／ｍ²）と厚紙（１２８ｇ／ｍ²）にプリントした際の文字周辺部へのトナー飛び散り（図９（ｂ）の状態）を目視で評価した。
【０３３５】
Ａ：ほとんど発生せず。
【０３３６】
Ｂ：軽微な飛び散りが見られる。
【０３３７】
Ｃ：若干の飛び散りが見られる。
【０３３８】
Ｄ：顕著な飛び散りが見られる。
【０３３９】
＜６＞画像中抜け
図１０（ａ）に示した「驚」文字パターンを厚紙（１２８ｇ／ｍ²）にプリントした際の文字の中抜け（図１０（ｂ）の状態）を目視で評価した。
【０３４０】
Ａ：中抜けはほとんど発生せず。
【０３４１】
Ｂ：軽微な中抜けが見られる。
【０３４２】
Ｃ：若干の中抜けが見られる。
【０３４３】
Ｄ：顕著な中抜けが見られる。
【０３４４】
［画像形成装置マッチング評価］
＜１＞現像スリーブとのマッチング
プリントアウト試験終了後、現像スリーブ表面への残留トナーの固着の様子とプリントアウト画像への影響を目視で評価した。
【０３４５】
Ａ：固着は未発生。
【０３４６】
Ｂ：固着はほとんど発生せず。
【０３４７】
Ｃ：固着があるが、画像への影響が少ない。
【０３４８】
Ｄ：固着が多く、画像ムラを生じる。
【０３４９】
＜２＞感光ドラムとのマッチング
プリントアウト試験終了後、感光体ドラム表面の傷や残留トナーの固着の発生状況とプリントアウト画像への影響を目視で評価した。
【０３５０】
Ａ：傷及び固着は未発生。
【０３５１】
Ｂ：わずかに傷の発生が見られるが、画像への影響はない。
【０３５２】
Ｃ：固着や傷があるが、画像への影響が少ない。
【０３５３】
Ｄ：固着が多く、縦スジ状の画像欠陥を生じる。
【０３５４】
＜３＞中間転写体とのマッチング
プリントアウト試験終了後、中間転写体表面の傷や残留トナーの固着状況を目視で評価した。
【０３５５】
Ａ：傷及び固着は未発生。
【０３５６】
Ｂ：表面に残留トナーの存在が認められるものの画像への影響はない。
【０３５７】
Ｃ：固着や傷があるが、画像への影響が少ない。
【０３５８】
Ｄ：固着が多く、画像欠陥を生じる。
【０３５９】
＜４＞帯電ローラーとのマッチング
プリントアウト試験終了後、帯電ローラー表面のトナーの付着状況を目視で評価した。
【０３６０】
Ａ：ほとんど付着せず。
【０３６１】
Ｂ：軽微な付着が見られる。
【０３６２】
Ｃ：若干の付着が見られる。
【０３６３】
Ｄ：顕著な付着が見られる。
【０３６４】
【発明の効果】
以上説明したように、本発明によれば、現像工程時に静電潜像担持体の表面に残存しているトナーをトナー担持体が回収することによって静電潜像担持体表面のクリーニングが行われる現像同時クリーニング方式を有する画像形成装置に用いられるトナーの形状分布を精密に制御することにより、高品位な画像形成性と、画像形成装置との安定したマッチングを得ることができる。
【図面の簡単な説明】
【図１】本発明に好適な二成分現像プロセスを用いた画像形成装置の概略的説明図である。
【図２】本発明に好適な二成分現像プロセスに用いられる画像形成装置の要部の拡大横断図である。
【図３】本発明に好適な一成分現像プロセスを用いた画像形成装置の概略的説明図である。
【図４】本発明に好適なブレードクリーニング装置を具備した中間転写ベルトを用いた画像形成装置の概略的説明図である。
【図５】本発明に好適な帯電ローラークリーニング装置を具備した中間転写ベルトを用いた画像形成装置の概略的説明図である。
【図６】ワックス成分を内包化しているトナー粒子の断面の一例を示す模式図である。
【図７】本発明に係るワックス成分の昇温時におけるＤＳＣ曲線の概略的説明図である。
【図８】トナーの現像特性をチェックする為の孤立ドットパターンの説明図である。
【図９】文字画像の飛び散りの状態を示す模式図である。
【図１０】文字画像の中抜けの状態を示す模式図である。
【符号の説明】
１ 現像剤担持体
２ 感光体（像担持体）
４ 転写材
５ 帯電ブラシローラー
１３ 非磁性ブレード
１５ 現像器
１６ 二成分系現像剤
２４ 磁石
３０ トナー
３１ 帯電ローラー
３２ 現像容器
３３ トナー規制ブレード
３４ トナー担持体（弾性ローラー）
３５ トナー塗布ローラー
３６ 感光体（像担持体）
３７ 転写ローラー
３８ 転写材
４１ 現像バイアス印加手段
４２ 転写バイアス印加手段
４３ 定着器
５１ 感光ドラム
５２ 帯電ローラー
５３ 像露光手段
５４ 転写残トナークリーニング装置
５５ 転写残トナー帯電部材
５６ バイアス電源
６２ 一次転写ローラ
６３ 二次転写ローラ
７１ イエロー色現像装置
７２ マゼンタ色現像装置
７３ シアン色現像装置
７４ ブラック色現像装置
７６ バイアス電源
７７ 中間転写ベルト
７８ バイアス電源
Ｐ 転写材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method using an electrophotographic method, an electrostatic recording method, or a magnetic recording method. More specifically, the present invention relates to an image forming method used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, which forms a toner image on a photosensitive member and then transfers the toner image onto a transfer material to form an image. It is.
[0002]
[Prior art]
Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the electric latent image is converted into a toner. The image is developed with a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat or pressure to obtain a fixed image. is there. At this time, the toner remaining on the photoreceptor without being transferred to the transfer material after the transfer is cleaned by various methods, and the above-described steps are repeated.
[0003]
As a method for visualizing an electric latent image, a cascade development method, a magnetic brush development method, a nonmagnetic one-component development method, and a pressure development method are known. Furthermore, a magnetic one-component developing method is also used in which a magnetic toner is used and a rotating sleeve having a magnetic pole at the center is used to fly between the photosensitive member and the sleeve by an electric field.
[0004]
LED and LBP printers have become the mainstream in the recent market, and the direction of technology is higher resolution, that is, what is conventionally 240 dpi or 300 dpi has become 400 dpi, 600 dpi, or 1200 dpi. Accordingly, the development method is also required to have higher definition. Copiers are also becoming more sophisticated, and are therefore moving toward digitalization. In the digital system, a method of forming an electrostatic charge image with a laser is mainly used, so that the resolution is still high, and a high-resolution and high-definition developing system is required as in the case of a printer.
[0005]
For this reason, the toner particle size has been reduced, and Japanese Patent Application Laid-Open Nos. 1-112253, 1-1191156, 2-214156, 2-284158, and 3-181955. No. 4-162048 proposes a toner having a specific particle size distribution and a small particle size.
[0006]
In recent years, there has been proposed a so-called one-component contact development method in which development is performed by using a semiconductive development roller or a development roller having a dielectric layer formed on the surface thereof and pressing the photosensitive member surface layer.
[0007]
In the one-component development method, when the photoreceptor and the toner carrier are not in contact with each other, the lines of electric force concentrate on the edge portion of the electrostatic latent image on the photoreceptor, and the toner is developed along the lines of electric force. In addition, the image quality is likely to deteriorate due to an edge effect in which toner is biased and developed at the edge portion of the image.
[0008]
This edge effect is prevented by bringing the photosensitive member and the toner carrier very close to each other. However, when the gap between the photosensitive member and the toner carrier is mechanically set, the gap is larger than the thickness of the toner layer on the toner carrier. It is difficult to set a small value.
[0009]
Therefore, a one-component contact development method in which development is performed by pressing the toner carrier against the photosensitive member is effective in preventing the edge effect. However, if the toner carrier surface moving speed is the same as the photosensitive member surface moving speed, a satisfactory image cannot be obtained when the latent image on the photosensitive member is visualized. Therefore, in the one-component contact development method, by making a difference in the toner carrier surface movement speed with respect to the photoreceptor surface movement speed, a part of the toner on the toner carrier is made to the latent image on the photoreceptor surface. It is developed and some other toner is stripped off, resulting in a developed image without edge effects that is very faithful to the latent image.
[0010]
In such a one-component contact development method, since the surface of the photoreceptor is rubbed with toner and the toner carrier, toner deterioration, toner carrier surface degradation, photoreceptor surface degradation or wear is likely to occur due to long-term use. The deterioration of durability characteristics remains as a problem, and this improvement method has been desired. Therefore, in the one-component contact development method, it is necessary to improve the durability characteristics of the image forming process for such a reason, and further, there is an essential problem that it is difficult to increase the speed by applying a load.
[0011]
Japan Hardcopy '89 Proceedings, pages 25 to 28, discusses a contact-type one-component non-magnetic development system. However, the durability characteristics are not mentioned.
[0012]
FUJITSU Sci. Tech. J. et al. , 28, 4, pp. 473-480 (December 992) reports an outline of a printer using a one-component contact development method. However, the durability characteristics are not sufficient and there is room for further improvement.
[0013]
Japanese Patent Laid-Open Nos. Hei 5-188852 and Hei 5-188765 disclose techniques relating to a one-component contact development method, and both of them disclose techniques for improving durability characteristics and durability. Not.
[0014]
On the other hand, the toner image formed on the photoconductor in the development process is transferred to the transfer material in the transfer process, but the residual transfer toner remaining on the photoconductor is cleaned in the cleaning process, and the toner is stored in the waste toner container. It is done. For this cleaning process, conventionally, cleaning methods such as blade cleaning, fur brush cleaning, and roller cleaning have been used. In any of the cleaning methods, a cleaning member is brought into contact with the surface of the photosensitive member to mechanically scrape off or remove the residual toner after transfer, and collect it in a waste toner container. Therefore, all of these cleaning methods have problems caused by the pressing of the cleaning member against the surface of the photosensitive member, for example, the pressing of the cleaning member strongly causes the photosensitive member to wear and shorten the life of the photosensitive member. It was. Further, from the standpoint of the apparatus, the apparatus becomes inevitably large in order to have such a cleaning apparatus, which has become a bottleneck when aiming for a compact image forming apparatus.
[0015]
Furthermore, from the viewpoint of ecology, there has been a demand for a system without waste toner for the purpose of effective use of toner and a system excellent in fixing property and offset resistance from the viewpoint of energy saving.
[0016]
The disclosure of the technique called the conventional simultaneous development cleaning method or cleanerless method focuses on positive memory and negative memory due to the influence of residual toner on the image as disclosed in Japanese Patent Laid-Open No. 5-2287. there were. However, as the use of electrophotography progresses, it is necessary to transfer toner images to various transfer materials. In this sense, the transfer images are not satisfactory.
[0017]
Prior arts that disclose technologies related to the cleanerless system include Japanese Patent Application Laid-Open Nos. 59-133573, 62-203182, 63-133179, and 64- No. 20587, JP-A-2-302773, JP-A-5-2289, JP-A-5-53482, and JP-A-5-61383, all of which are desirable images. It does not describe the formation method, nor does it mention the toner configuration.
[0018]
Furthermore, in the development simultaneous cleaning method in which the cleaning process also serves as the development process at the time of development, a structure in which the surface of the photoconductor is rubbed with the toner and the toner carrier is indispensable. However, since the surface of the photoreceptor is deteriorated or worn, and the durability is easily deteriorated, the prior art cannot solve the problem sufficiently, and both the fixing property and the durability are desired. At the same time, where speeding up of image formation is desired at the same time, in the simultaneous development cleaning of a device with a faster process speed, the charge of the residual toner in the transfer is controlled in order to improve the recoverability of the residual toner in the development. In terms of maintaining the stability of development during reuse, the prior art does not provide a sufficient solution.
[0019]
Japanese Patent Laid-Open No. 3-259161 provides a non-magnetic one-component developer in which a shape factor, a specific surface area, and a particle size are defined. However, the developer defined in this prior art has insufficient durability. Met.
[0020]
Japanese Patent Application Laid-Open No. 61-279864 proposes a toner that defines shape factors SF1 and SF2. However, this prior art has no description regarding transfer, and as a result of reexamining the examples, the transfer efficiency is low and further improvement is required.
[0021]
Japanese Patent Application Laid-Open No. 63-235953 proposes a magnetic toner that is spheroidized by a mechanical impact force. However, in this prior art, the transfer efficiency is still insufficient and further improvement is required.
[0022]
In recent years, from the viewpoint of environmental protection, in a conventional primary charging process and transfer process using corona discharge, a contact charging method in which charging is performed by bringing a charging member into contact with the surface of the photoconductor, and transfer to the surface of the photoconductor A contact transfer method in which transfer is performed by bringing a transfer member into contact with each other through a material is becoming mainstream.
[0023]
Such a contact charging method and a contact transfer method are proposed in, for example, Japanese Patent Laid-Open Nos. 63-149669 and 2-123385. In these methods, a conductive elastic roller is brought into contact with the photosensitive member, and the photosensitive member is uniformly charged while applying a voltage to the conductive roller, and then a toner image is obtained by an exposure and development process. A transfer material is passed while pressing another conductive roller to which a voltage is applied, and a toner image on the photoreceptor is transferred to the transfer material, and then a copy image is obtained through a fixing step.
[0024]
However, in such a contact transfer method, the transfer member is brought into contact with the photoconductor via the transfer material at the time of transfer, so that the toner image is formed when the toner image formed on the photoconductor is transferred to the transfer material. There arises a problem of partial transfer failure, which is referred to as a so-called “transfer dropout”.
[0025]
Furthermore, as the diameter of the toner decreases, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photoconductor becomes larger than the Coulomb force applied to the toner particles during transfer, resulting in residual transfer. There was a tendency for toner to increase.
[0026]
Therefore, the toner and the photoreceptor used in such an image forming method are required to have excellent releasability.
[0027]
In order to improve the releasability of the toner from the photoconductor and improve the transferability of the toner, it is possible to use a nearly spherical toner manufactured by suspension polymerization, as disclosed in Japanese Patent Application Laid-Open No. 7-209952 (corresponding US Pat. No. 5,659,857).
[0028]
Toners produced by the suspension polymerization method have been proposed for a long time (for example, Japanese Patent Publication No. 36-10231). In this suspension polymerization method, a monomer composition is prepared by uniformly dissolving or dispersing a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives). Then, the monomer composition is dispersed in a continuous phase (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and a polymerization reaction is performed, whereby toner particles having a desired particle size are obtained. Is what you get.
[0029]
In this suspension polymerization method, droplets of the monomer composition are generated in a dispersion medium having a large polarity such as water. Therefore, the component having a polar group contained in the monomer composition is an interface with the aqueous phase. Thus, it is possible to produce a spherical toner having a so-called core / shell structure or sea-island structure in which a non-polar component does not exist in the surface layer portion.
[0030]
The toner by the polymerization method has been able to satisfy both the low-temperature fixing property and the anti-blocking property and the high-temperature offset-resistant property by embedding the wax component as a release agent.
[0031]
When such a toner is used, it is difficult to expose the colorant to the surface, and there is an advantage that the toner has uniform triboelectric chargeability. Furthermore, since the classification process can be omitted, the manufacturing cost reduction effect such as energy saving, time reduction, and process yield improvement is great.
[0032]
However, since the toner obtained by this method has a substantially spherical shape, a cleaning failure due to toner particle abrasion occurs during cleaning in the above-described electrophotographic process, particularly blade cleaning, and copying. The image quality may be significantly impaired.
[0033]
In particular, in non-magnetic one-component contact development, the charge amount of the toner developed on the photoconductor is high, and the adhesion force (mirror power) of the toner particles to the photoconductor is increased, resulting in an increase in the residual toner after transfer. Tend to. There is also a tendency that the charge amount of the toner remaining after transfer tends to be high, and the adhesion force of the toner particles to the photosensitive member is also increased, so that a cleaning failure tends to occur during cleaning.
[0034]
On the other hand, even in the development simultaneous cleaning system in which the cleaning process for removing the transfer residual toner from the surface of the photoreceptor also serves as the development process at the time of development, when spherical toner is used, the external additive is not used when used for a long time. The toner tends to be buried in the toner surface, and the chargeability of the toner is lowered, resulting in the deterioration of the image quality as a result. In particular, this phenomenon becomes more prominent as the process speed of the developing roller becomes higher.
[0035]
Incidentally, the toner needs to have a positive or negative charge depending on the polarity of the electrostatic latent image to be developed.
[0036]
In order to retain the charge in the toner, it is possible to use the triboelectric charging property of the resin, which is a component of the toner. However, since this method does not stabilize the charging of the toner, the rise of density is slow and fogging is easy. Therefore, a charge control agent is added in order to impart a desired triboelectric chargeability to the toner.
[0037]
As a charge control agent known in the technical field today, as a negative triboelectric charge control agent, a metal complex salt of a monoazo dye, a metal complex salt such as hydroxycarboxylic acid, dicarboxylic acid, aromatic diol, and an acid component are included. Resins and the like are known. As the positive triboelectric charge control agent, nigrosine dyes, azine dyes, triphenylmethane dyes and pigments, polymers having quaternary ammonium salts and quaternary ammonium salts in the side chain are known.
[0038]
However, most of these charge control agents are colored and cannot be used for color toners. Most colorless, white, or light color toners that can be applied to color toners are insufficient in performance. They have drawbacks such as failure to obtain highlight uniformity and large variations in image density in the durability test.
[0039]
In addition, some charge control agents have the following drawbacks. It is difficult to balance image density and fog, it is difficult to obtain sufficient image density in a high humidity environment, dispersibility in resin is poor, storage stability, fixability, and offset resistance are adversely affected.
[0040]
Conventionally, metal complexes and metal salts of aromatic carboxylic acids are disclosed in JP-A-53-127726, JP-A-57-111541, JP-A-57-124357, JP-A-57-104940, JP-A-61-69073, JP-A-61-73963, JP-A-61-267058, JP-A-62-105156, JP-A-62-145255, JP-A-62-163061 Several proposals have been made such as Japanese Patent Application Laid-Open No. 63-208865, Japanese Patent Application Laid-Open No. 3-276166, Japanese Patent Application Laid-Open No. 4-84141, and Japanese Patent Application Laid-Open No. 8-160668. However, these publications have proposed all of them from the viewpoint of imparting frictional charge, but with a simple developing device configuration, stable developability regardless of environmental fluctuations, aging, and usage conditions. There are few things that can be obtained. In addition, few high-speed machines can obtain stable developability even during long-term durability. Furthermore, there are many cases where other raw materials are affected, and other raw materials are restricted. At present, none of the above items is satisfactory.
[0041]
It is also known to contain an azo-based iron complex compound as a charge control agent in the toner.
[0042]
Japanese Patent Laid-Open No. 7-281485 proposes a suspension polymerization toner in which a specific azo-based iron complex compound is contained in a toner and the chargeability is improved by a nonmagnetic one-component development method. However, carbon black that greatly affects the polymerizability and chargeability of the toner has not been studied.
[0043]
Furthermore, in the image development method of the simultaneous development cleaning system, there has not yet been found a prior art that sufficiently solves the problems in using the toner containing carbon black.
[0044]
[Problems to be solved by the invention]
The object of the present invention is to significantly improve the drawbacks of the prior art, improve the developability and environmental stability, and realize a high-quality image stably over a long period of time, adversely affecting the image forming apparatus. It is an object of the present invention to provide an image forming method capable of advanced application to an electrophotographic process.
[0045]
[Means and Actions for Solving the Problems]
  The present invention includes a charging step in which a voltage is applied to the charging member from the outside to charge the electrostatic latent image carrier, and a latent image forming step in which an electrostatic latent image is formed on the charged electrostatic latent image carrier. The developer layer formed by the developer having the toner carried on the surface of the developer carrying member comes into contact with the surface of the electrostatic latent image carrying member, thereby developing the electrostatic charge image to static the toner image. A developing process for forming on the electrostatic latent image carrier, a transfer process for transferring a toner image on the electrostatic latent image carrier to a transfer material, and a toner remaining on the surface of the electrostatic latent image carrier after the transfer process In an image forming method having at least a cleaning step of recovering the toner and a fixing step of heating and fixing the toner image on the transfer material,
  The cleaning step is performed using a cleaning method in which the developer carrying member collects the toner remaining on the surface of the electrostatic latent image carrying member during the developing step, thereby cleaning the surface of the electrostatic latent image carrying member. And
  The toner contains at least a binder resin, a colorant, and a wax component. The toner has a circle equivalent diameter-circularity scattergram based on the number of toners measured by a flow type particle image measuring device. Equivalent number average diameter (D₁) Is 2 to 10 μm, and the average circularity of the toner is0.970~0.990And the circularity standard deviation is0.015 or more and less than 0.035InThe
  In the equivalent circle diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the toner contains 15% by number or less of toner particles having a circularity of less than 0.950.The present invention relates to an image forming method.
[0046]
  Furthermore, the present invention provides at least a charging step in which a voltage is applied to the charging member from the outside to charge the electrostatic latent image carrier, and a latent image for forming an electrostatic latent image on the charged electrostatic latent image carrier. A developer layer formed by an image forming step and a developer having toner carried on the surface of the developer carrying member is in contact with the surface of the electrostatic latent image carrying member; A developing step of developing the electrostatic image by moving the surface and the surface of the toner carrying member relative to each other to form a toner image on the electrostatic latent image carrying member; and a toner image on the electrostatic latent image carrying member. A first transfer step for transferring to the intermediate transfer member, a second transfer step for transferring the toner image on the intermediate transfer member to the transfer material, and a surface remaining on the surface of the electrostatic latent image carrier after the first transfer step. A cleaning process for collecting the remaining toner and a fixing process for heating and fixing the toner image on the transfer material. In the image forming method having even without,
  The first cleaning step uses a cleaning method in which the toner carrier collects the toner remaining on the surface of the electrostatic latent image carrier during the development step, thereby cleaning the surface of the electrostatic latent image carrier. Performed and
  The toner contains at least a binder resin, a colorant, and a wax component. The toner has a circle equivalent diameter-circularity scattergram based on the number of toners measured by a flow type particle image measuring device. Equivalent number average diameter (D₁) Is 2 to 10 μm, and the average circularity of the toner is0.970~0.990And the circularity standard deviation is0.015 or more and less than 0.035InThe
  In the equivalent circle diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the toner has 15% by number or less of toner particles having a circularity of less than 0.950.The present invention relates to an image forming method.
[0047]
The inventors of the present invention provide an image forming apparatus that gives a desirable electrophotographic characteristic to the toner by precisely controlling the shape distribution of the toner, and applies the one-component contact developing method using the simultaneous development cleaning method to the toner. When used, it has been found that stable matching with the image forming apparatus can be obtained, and high-quality image formation can be performed.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
That is, the number average diameter equivalent to the circle (D₁) Is 2 to 10 μm, and the toner has a mean circularity of 0.920 to 0.995 and a circularity standard deviation of less than 0.040, by precisely controlling the particle shape of the toner, While improving developability and transferability in a well-balanced manner, matching with an image forming apparatus such as recoverability of toner remaining after transfer is remarkably improved.
[0049]
Toner circle equivalent number average diameter (D₁) Is reduced to 2 to 10 [mu] m, the reproducibility of image contours, particularly character images and line patterns, is improved. However, in general, when the toner particle size is reduced, the presence rate of the toner having a small particle size inevitably increases, so that it is difficult to uniformly charge the toner and image fogging occurs. The adhesion force to the surface of the body and the toner carrier increases, resulting in an increase in residual toner and the above-described problems.
[0050]
However, in the toner of the present invention, the circularity standard deviation is less than 0.040, preferably less than 0.035, more preferably 0.010 or more and less than 0.035. can do. The reason for this is that when the toner layer is formed on the toner carrier in the development process, the present inventors can maintain a sufficient toner coat amount even if the regulating force of the toner layer regulating member is stronger than usual. Therefore, it is considered that the damage received from the toner carrier is minimized and the toner charge amount on the toner carrier can be made appropriate.
[0051]
In addition, the average circularity of the circularity frequency distribution is 0.920 to 0.995, preferably 0.950 to 0.995, and more preferably the average circularity is 0.970 to 0.990. The transfer performance of a toner having a small particle diameter, which was difficult to achieve, is greatly improved, and the developing ability for a low potential latent image is remarkably improved. This is particularly effective when developing a digital microspot latent image adapted to a nonmagnetic one-component contact development method.
[0052]
First, a cleaning method in which the surface of the electrostatic latent image carrier is cleaned by collecting the toner remaining on the surface of the electrostatic latent image carrier during the development process, that is, a developing and cleaning method is used. The principle of the used image forming method will be described.
[0053]
The principle is to control the charge polarity and charge amount of the toner on the photoreceptor in each electrophotographic process and to use a reversal development method.
[0054]
For example, when a negatively chargeable photoreceptor and negatively chargeable toner are used, in the transfer process, an image visualized by a transfer member to which a positive potential is applied is transferred to a transfer material. However, depending on the relationship between the type of transfer material (difference in thickness, resistance, dielectric constant, etc.) and the image area, the charging polarity of the residual toner varies from negative chargeability to positive chargeability. However, due to the charging member to which a negative potential is applied when charging the negatively chargeable photoconductor, the transfer residual toner whose chargeability fluctuates to the positive side in the transfer process also uniformly aligns the charging polarity to the negative side. I can do it. Therefore, when reversal development is used as the developing method, the toner remaining on the photosensitive portion is left with a retransfer residual toner that is negatively recharged in the light potential portion where the toner is to be developed, and the toner should not be developed. The dark portion potential is attracted toward the toner carrying member by the developing electric field, and the transfer residual toner is cleaned from the photosensitive member having the dark portion potential.
[0055]
However, when an image is formed at a higher process speed, the toner remaining on the transfer surface is uniformly charged together with the surface of the photosensitive member by the charging member in correlation with a decrease in the charging time per surface area of the photosensitive member. It becomes difficult to align the polarities. Therefore, when reversal development is used as the development method, it is difficult to collect the residual toner on the dark portion potential that should not be developed by the toner by being attracted to the toner carrier by the development electric field. Even if the toner carrier is recovered by mechanical force such as rubbing, if the charge of the residual toner is not uniform, the chargeability of the toner on the toner carrier is adversely affected and Degrading properties.
[0056]
By controlling the charging polarity of the residual toner at the same time as the charging of the photosensitive member, an image forming method based on the development and cleaning method is established. However, when the image forming method based on the development and cleaning method is applied to an image forming apparatus with a higher process speed as described above, it becomes difficult to control the charging polarity of the toner remaining in the transfer, resulting in poor collection during development. There is a problem in that the chargeability of the transfer residual toner collected by the development is greatly affected by the development characteristics, and the development performance is liable to be deteriorated.
[0057]
Also, charging failure due to contamination of the charging member is likely to occur.
[0058]
According to the study by the present inventors, in the image forming method based on the development and cleaning method of the higher process speed system, the charge polarity is more quickly controlled in order to improve the recoverability of the transfer residual toner in the development. In order to maintain the development performance, it has been found that the charge polarity of the residual toner after transfer must be more reliably and uniformly controlled when passing through the charging member.
[0059]
In particular, in the so-called direct charging method in which the charging member and the photosensitive member are brought into contact with each other for charging, the charging member is in contact with the photosensitive member in the case of using discharge according to the so-called Paschen's law as the charging mechanism. In addition, adhesion to the charging member is also deteriorated due to toner deterioration due to the discharge energy.
[0060]
Conventionally, a transfer residual toner is cleaned from the photosensitive member by a cleaning member such as a blade or a fur brush, and the toner existing on the photosensitive member is charged, collected by the developing device, and this toner is used as the developing device. No consideration has been given to the effect on development performance when it is collected and reused.
[0061]
The present inventors have intensively studied various toners, and in the image forming method using the developing and cleaning method, the charge control characteristics when the toner passes through the charging member are closely related to the durability characteristics and the image quality characteristics. It has been found that there is a connection, and further, by controlling the shape distribution of the toner precisely, it has been found that the charge control characteristics when the toner passes through the charging member are improved, and the present invention has been achieved.
[0062]
In the present invention, the equivalent-circle diameter, circularity, and frequency distribution of the toner are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring device FPIA- Measurement was performed using a 1000 model (manufactured by Toa Medical Electronics Co., Ltd.), and the calculation was performed using the following formula.
[0063]
[Expression 1]

[0064]
Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.
[0065]
In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity.
[0066]

[0067]
[Expression 2]

[0068]

[0069]
[Equation 3]

[0070]
As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a 5φ titanium alloy chip as a vibrator is used, and a dispersion for measurement is made using a dispersion treatment for 5 minutes. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more.
[0071]
To measure the shape of the toner particles, the flow type particle image measuring device is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 / μl, and 1000 toner particles are obtained. Measure above. After the measurement, this data is used to determine the equivalent circle diameter of the toner, the circularity frequency distribution, and the like.
[0072]
The wax component according to the present invention is substantially spherical and / or spindle-shaped and island-shaped in a state where the wax component is not compatible with the binder resin in the tomographic observation of the toner using a transmission electron microscope (TEM). Is distributed.
[0073]

[0074]
By dispersing the wax component as described above and encapsulating it in the toner, it is possible to prevent toner deterioration and contamination of the image forming apparatus. Particularly when the average value of r / R is in a dispersion state satisfying 0.25 ≦ r / R ≦ 0.90, good chargeability can be maintained and a toner image excellent in dot reproduction can be formed over a long period of time. This is preferable because it becomes possible. Further, since the wax component acts efficiently during heating, the low-temperature fixability and offset resistance are satisfied.
[0075]
In the present invention, as a specific method for observing the tomographic plane of the toner, four cured products obtained by sufficiently dispersing toner particles in a room temperature curable epoxy resin and then curing in an atmosphere at a temperature of 40 ° C. After staining with ruthenium trioxide and, if necessary, osmium tetroxide, a flaky sample is cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner is observed using a transmission electron microscope (TEM). In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide contrast between materials by utilizing a slight difference in crystallinity between the low softening point substance used and the resin constituting the outer shell. A typical example is shown in FIG. In the toner particles obtained in Examples described later, it was observed that the low softening point substance was encapsulated with the outer shell resin.
[0076]
The wax component according to the present invention has a maximum endothermic peak in the region of 50 to 100 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter, and the onset temperature at the start point of the endothermic peak including the maximum endothermic peak Is preferably 40 ° C. or higher, and in particular, the temperature difference between the peak temperature of the maximum endothermic peak and the onset temperature is preferably in the range of 7 to 50 ° C.
[0077]
By using a wax component that melts in the above temperature range in the DSC curve at the time of temperature rise, the dispersibility of other additives can be improved, and the wax component itself can be easily dispersed as described above. Can be controlled.
[0078]
As a result, not only good fixability of the toner but also a release effect by the wax component is effectively expressed, a sufficient fixing area is ensured, and developability, blocking resistance and image by the conventionally known wax component are ensured. Since the adverse effect on the forming apparatus is eliminated, these characteristics are remarkably improved. In particular, as the particle shape becomes spherical, the specific surface area of the toner decreases, so controlling the dispersion state of the wax component is very effective.
[0079]
In the DSC measurement in the present invention, since the heat exchange of the wax is measured and the behavior is observed, it is preferable to measure with a differential scanning calorimeter of high accuracy internal heat input compensation type from the measurement principle. For example, DSC-7 manufactured by Perkin Elmer can be used.
[0080]
The measurement method is performed according to “ASTM D3418-82”. The DSC polarity used in the present invention uses a DSC curve that is measured when the temperature is raised at a temperature rate of 10 ° C./min after once raising / lowering the temperature and taking the previous history when measuring only the wax component. Further, when the measurement is performed in a state of being included in the toner, a DSC curve that is measured without using the previous history is used.
[0081]
Each temperature exhibited by the wax component specified in the present invention is defined as follows.
[0082]
(Maximum endothermic peak)
In the DSC curve obtained at the time of temperature rise, the peak top temperature of the peak showing the maximum endothermic peak in the temperature range of 50 to 100 ° C. (corresponding to MP in FIG. 7).
[0083]
(Onset temperature at the end of the endothermic peak)
The temperature at the intersection of the tangent of the curve and the base line at the point where the differential value of the DSC curve obtained at the time of temperature rise first becomes maximum (corresponding to SP in FIG. 7).
[0084]
Examples of the wax component according to the present invention include petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof according to the Fischer-Tropsch method, and polyolefins represented by polyethylene Wax and its derivatives, carnauba wax, candelilla wax, natural wax and their derivatives, etc. The derivatives include oxides, block copolymers with vinyl monomers, graft modified products, and higher aliphatic alcohols. Alcohols such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes. These can be used alone or in combination.
[0085]
Of these, polyolefin, Fischer-Tropsch hydrocarbon wax, petroleum wax, higher alcohol, or higher ester can further improve the developability and transferability.
[0086]
An antioxidant may be added to the wax component as long as the chargeability of the toner is not affected.
[0087]
The wax component described above is preferably used in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin.
[0088]
Examples of the binder resin used in the toner of the present invention include commonly used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins, and styrene-butadiene copolymers. In a method for directly obtaining toner particles by a polymerization method, a monomer for forming them is used. Specifically, styrene; styrene-based monomers such as o- (m-, p-) methylstyrene, m- (p-) ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as dimethylaminoethyl acrylate, diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile, acrylamide Preferably used. These may be used alone or in general so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-P139-192 (John Wiley & Sons) is 40-75 ° C. It is used by appropriately mixing the monomer. When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, while when it exceeds 75 ° C., the fixing point of the toner is increased. In particular, in the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is lowered, the color reproducibility is poor, and the transparency of the OHP image is further lowered.
[0089]
The molecular weight of the binder resin is measured by gel permeation chromatography (GPC). In the case of a toner having a so-called core-shell structure in which a low softening point material is encapsulated with an outer shell resin, as a specific GPC measurement method, the toner was previously extracted with a toluene solvent using a Soxhlet extractor for 20 hours. Thereafter, toluene is distilled off with a rotary evaporator to obtain an extract. Further, an organic solvent that dissolves the low softening point substance but does not dissolve the outer shell resin (for example, chloroform) is added to the extract and sufficiently washed. A sample (THF solution) obtained by filtering a solution obtained by dissolving the residue in tetrahydrofuran (THF) through a solvent-resistant membrane filter having a pore size of 0.3 μm is measured using 150C manufactured by Waters. The column structure can connect A-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko and measure the molecular weight distribution using a standard polystyrene resin calibration curve. The main peak molecular weight of the binder resin according to the present invention is 5,000 to 1,000,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 to 100. Is preferred.
[0090]
In the present invention, the above binder resin and a resin having polarity such as polyester and polycarbonate can be used in combination. Among them, it is preferable to use together a polycarbonate resin having a repeating unit represented by the following general formula (I) in the molecular structure, which improves toner charging characteristics, improves image fogging and scattering, and excels in dot reproducibility. A high-quality image can be obtained. In addition, it is possible to impart an appropriate mechanical strength to the toner, which not only improves matching with the image forming apparatus, but also affects the toner deterioration in the toner drying process and spheroidizing process as described above. Since it can be minimized, performance is synergistically improved.
[0091]
[Chemical Formula 3]

[Wherein R represents an organic group. ]
[0092]
The general formula (I) has various structures. For example, any known polycarbonate produced by reacting a dihydric phenol and a carbonate precursor by a solution method or a melt method can be used. In the following general formula (II)
[0093]
[Formula 4]

[In the formula, R²Is a hydrogen atom, an aliphatic hydrocarbon group or an aromatic substituent.²Are a plurality, they may be the same or different, and m is a number from 0 to 4. Z is a single bond, an aliphatic hydrocarbon group, an aromatic substituent, -S-, -SO-, -SO₂A bond represented by a —, —O—, or —CO— bond is shown. And a polymer having a repeating unit having a structure represented by the formula:
[0094]
This polycarbonate resin can be applied to various materials, but is usually represented by the general formulas (III) to (V).
[0095]
[Chemical formula 5]

[0096]
[Chemical formula 5]

[0097]
[Chemical 7]

(Wherein R², M and Z are the same as described above. ) And a carbonate precursor such as phosgene or a carbonate ester compound can be easily produced. That is, for example, in the presence of a known acid acceptor or molecular weight regulator in a solvent such as methylene chloride, by reaction of a dihydric phenol with a carbonate precursor such as phosgene, or like dihydric phenol and diphenyl carbonate. Produced by transesterification with a carbonate precursor.
[0098]
There are various dihydric phenols represented by the above general formulas (III) to (V), such as 2,2-bis (4-hydroxyphenyl) propane (common name: bisphenol A), for example, bis (4 -Hydroxyphenyl) methane; bis (4-hydroxyphenyl) phenylmethane; bis (4-hydroxyphenyl) naphthylmethane; bis (4-hydroxyphenyl)-(4-isopropylphenyl) methane; bis (3,5-dimethyl- 4-hydroxyphenyl) methane; 1,1-bis (4-hydroxyphenyl) ethane; 1-naphthyl-1,1-bis (4-hydroxyphenyl) ethane; 1-phenyl-1,1-bis (4-hydroxy) Phenyl) ethane; 1,2-bis (4-hydroxyphenyl) ethane; 2-methyl-1,1-bis (4- Droxyphenyl) propane; 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane; 1-ethyl-1,1-bis (4-hydroxyphenyl) propane; 2,2-bis (3- 1,4-bis (4-hydroxyphenyl) butane; 2,2-bis (4-hydroxyphenyl) butane; 1,4-bis (4-hydroxyphenyl) butane; 2-bis (4-hydroxyphenyl) pentane; 4-methyl-2,2-bis (4-hydroxyphenyl) pentane; 1,1-bis (4-hydroxyphenyl) cyclohexane; 2,2-bis (4-hydroxy) Phenyl) hexane; 4,4-bis (4-hydroxyphenyl) heptane; 2,2-bis (4-hydroxyphenyl) nonane; 1,10 Bis (4-hydroxyphenyl) decane; dihydroxyarylalkanes such as 1,1-bis (4-hydroxyphenyl) cyclodecane, bis (4-hydroxyphenyl) sulfone; bis (3,5-dimethyl-4-hydroxyphenyl) Dihydroxyaryl sulfones such as sulfone, bis (4-hydroxyphenyl) ether; dihydroxyaryl ethers such as bis (3,5-dimethyl-4-hydroxyphenyl) ether, 4,4′-dihydroxybenzophenone; 3,3 ′ , 5,5′-tetramethyl-4,4′-dihydroxybenzophenone, bis (4-hydroxyphenyl) sulfide; bis (3-methyl-4-hydroxyphenyl sulfide; bis (3,5- Dimethyl-4-hydro Dihydroxyaryl sulfides such as xyphenyl) sulfide, dihydroxyaryl sulfoxides such as bis (4-hydroxyphenyl) sulfoxide, dihydroxydiphenyls such as 4,4′-dihydroxydiphenyl, hydroquinone; solcinol; dihydroxybenzenes such as methylhydroquinone 1,5-dihydroxynaphthalene; dihydroxynaphthalene such as 2,6-dihydroxynaphthalene. These dihydric phenols may be used alone or in combination of two or more.
[0099]
Examples of the carbonate compound include diaryl carbonates such as diphenyl carbonate, and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate.
[0100]
The polycarbonate-based resin used in the present invention may be a homopolymer using one of these dihydric phenols, a copolymer using two or more, or a blend. There may be. Furthermore, the thermoplastic random branched polycarbonate resin obtained by making a polyfunctional aromatic compound react with the said dihydric phenol and / or a carbonate precursor may be sufficient.
[0101]
In order to adjust the glass transition temperature and viscoelasticity of the polycarbonate-based resin, a part of the dihydric phenol is ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1, 4-butanediol, neopentyl glycol, 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (2-hydroxyethyl) benzene, 1,4-cyclohexanedimethanol, polyethylene glycol, propylene glycol, hydrogenated bisphenol A and its derivatives, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, polyalcohol such as glycerin, trimethylolpropane, pentaerythritol, etc. Sex polycarbonate resin is also preferably used. In this case, it is possible to simply replace a part of the dihydric phenol and to produce the same by the method described above. However, as another example of the production method, the dihydric phenol and the aliphatic or aromatic bischloroformate are used. And pyridine as a catalyst in a methylene chloride solvent and the like. Of course, synthesis by other production methods is also possible.
[0102]
Furthermore, in the present invention, as the polycarbonate-based resin, the above-mentioned polycarbonate and polystyrene, styrene- (meth) acrylic copolymer, polyester, polyurethane, epoxy resin, polyolefin, polyamide, polysulfone, polycyanoaryl ether, polyarylene sulfide, and the like It is also possible to use a block-modified copolymer or a graft-modified copolymer grafted with an alkyl (meth) acrylate, (meth) acrylic acid, maleic acid, a styrene monomer or the like.
[0103]
The molecular weight of the polycarbonate resin used in the present invention is not particularly limited, but those having a peak molecular weight measured by GPC in the range of 1,000 to 500,000 are preferable, and more preferably 2000 to 100,000. If the peak molecular weight is lower than 1000, the charging characteristics may be adversely affected. If the peak molecular weight is higher than 500,000, the melt viscosity becomes too high, which may cause a problem in fixability. In producing the polycarbonate resin used in the present invention, an appropriate molecular weight regulator, a branching agent for improving viscoelasticity, a catalyst for accelerating the reaction and the like can be used as necessary.
[0104]
The content of the polycarbonate resin used in the present invention is not particularly limited, but is usually 0.1 to 50 parts by weight, preferably 0.2 to 40 parts by weight, more preferably 100 parts by weight of the total binder resin. 0.5 to 30 parts by weight. When the amount is less than 0.1 part by weight, the effect of addition is not manifested, and when the amount exceeds 50 parts by weight, a problem arises in toner chargeability, fixability, and matching with the image forming apparatus.
[0105]
In the present invention, it is one of the preferred embodiments that the polar resin as described above is used as the outermost resin layer provided on the toner surface.
[0106]
At this time, the glass transition temperature of the polar resin used in the outermost shell resin layer is designed to be higher than the glass transition temperature of the outer shell resin layer in order to further improve the blocking resistance, and to the extent that the fixing property is not impaired. It is preferably crosslinked. Further, the outermost resin layer preferably contains a polar resin or a charge control agent in order to improve chargeability.
[0107]
The method for providing the outermost shell layer is not particularly limited, and examples thereof include the following methods.
[0108]
1. In the latter half of the polymerization reaction or after completion, if necessary, add a monomer in which a polar resin, charge control agent, cross-linking agent, etc. are dissolved and dispersed in the reaction system and adsorb to the polymer particles, and then add a polymerization initiator to perform polymerization. How to do.
[0109]
2. If necessary, emulsion-polymerized particles or soap-free polymerized particles consisting of monomers containing a polar resin, a charge control agent, a crosslinking agent, etc. are added to the reaction system and aggregated on the surface of the polymerized particles. How to fix.
[0110]
3. A method in which emulsion-polymerized particles or soap-free polymerized particles comprising monomers containing a polar resin, a charge control agent, a crosslinking agent, etc. are mechanically fixed to the toner particle surface in a dry manner as required.
[0111]
The inclusion of a specific organometallic compound in the toner of the present invention is preferable because it improves the electrophotographic characteristics of the toner and improves the charge control characteristics when passing through the charging member, and particularly preferred are azo-based iron compounds and organic zirconium compounds. is there.
[0112]
As the azo-based iron compound, those having the following general formula are preferably used.
[0113]
[Chemical 8]

[Where X₁And X₂Represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom, and X₁And X₂May be the same or different, m and m 'each represent an integer of 1 to 3;₁And R_ThreeIs a hydrogen atom, C₁~ C₁₈Alkyl group of₂~ C₁₈Alkenyl group, sulfonamide group, mesyl group, sulfonic acid group, carboxyester group, hydroxy group, C₁~ C₁₈Represents an alkoxy group, an acetylamino group, a benzoylamino group or a halogen atom of R,₁And R_ThreeMay be the same or different, and n and n 'represent an integer of 1 to 3,₂And R_FourRepresents a hydrogen atom or a nitro group, and A⁺Represents a cation ion, and has an ammonium ion, a hydrogen ion, a sodium ion, a potassium ion, or a mixed ion thereof. ]
[0114]
The azo-based iron complex compound is also used as a negative charge control agent. The compound can be synthesized by a known method.
[0115]
Typical examples of the azo-type iron complex compound of the general formula include the following compounds.
[0116]
[Chemical 9]

[0117]
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[0118]
In the present invention, when the toner is formed by a polymerization method, carbon black and the azo-based iron complex compound are pre-dispersed in the polymerizable monomer to be used, thereby improving the dispersibility of the carbon black. It is remarkable. This is because the dispersion liquid has a high viscosity in order to disperse at a higher concentration, and the dispersion is performed with a high share.
[0119]
On the other hand, specific examples of the organic zirconium compound include (i) a zirconium complex having zirconium as a metal element and coordinating an aromatic diol, aromatic hydroxycarboxylic acid, or aromatic polycarboxylic acid as a ligand. Or a zirconium complex salt, (ii) a zirconium carboxylate salt having a zirconium ion as a metal ion and an aromatic carboxylate ion, an aromatic hydroxycarboxylate ion, or an aromatic polycarboxylate ion as an acid ion, etc. Is mentioned.
[0120]
The zirconium may contain less than 20 wt% of hafnium element based on the zirconium element. Further, as the ligand of the complex compound of zirconium and the aromatic carboxylate salt of zirconium, those having 2-4 chelates of aromatic diol, aromatic hydroxycarboxylic acid or aromatic polycarboxylic acid are preferable. Are preferably those having 2 to 3. Furthermore, it may be a complex or complex salt having a different number of chelate formations, or a complex or complex salt having a different ligand. Moreover, the mixture of the salt from which the ionization number of an acid ion differs may be sufficient.
[0121]
As the zirconium complex or zirconium complex salt of aromatic diol, aromatic hydroxycarboxylic acid, or aromatic polycarboxylic acid, an organic zirconium compound represented by the general formula (B-1) is preferable.
[0122]
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[0123]
In the general formula (B-1), Ar is an alkyl group, aryl group, aralkyl group, cycloalkyl group, alkenyl group, alkoxy group, aryloxy group, hydroxyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyl as a substituent. A group, an acyloxy group, a carboxyl group, a halogen, a nitro group, a cyano group, an amino group, an amide group, and a carbamoyl group. Represents an aromatic residue, X and Y represent -0-, -CO-O-, X and Y may be the same or different, L represents a neutral ligand, water, alcohol, Ammonia, alkylamine, pyridine, C1 represents a monovalent cation, hydrogen, monovalent metal ion, ammonium, alkylammonium, C2 represents a divalent cation, divalent metal ion, n is 2, 3 and 4 are represented, and m represents 0, 2, and 4. The aromatic carboxylic acids and aromatic diols that serve as ligands in each complex or complex salt may be the same or different. Further, it may be a mixture of complex compounds having different numbers of n and m. From the viewpoint of improving the dispersibility of the complex or complex salt in the binder resin or improving the chargeability, the aromatic residue is preferably a benzene ring, naphthalene ring, anthracene ring, or phenanthrene ring, and the substituent is an alkyl group. Carboxyl group and hydroxyl group are preferred, L is preferably water, and C1 is preferably hydrogen, sodium, potassium, ammonium, or alkylammonium.
[0124]
Further preferred zirconium complexes or salts are organic zirconium compounds represented by the general formulas (B-2), (B-3) and (B-4).
[0125]
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[0126]
In the general formulas (B-2), (B-3), and (B-4), R represents hydrogen, an alkyl group, an aryl group, an aralkyl group, a cycloalkyl group, an alkenyl group, an alkoxy group, an aryloxy group, and a hydroxyl group. Represents an acyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, a carboxyl group, a halogen, a nitro group, an amino group, or a carbamoyl group, which are linked together to form an aliphatic ring, an aromatic ring or a heterocyclic ring. In this case, the ring may have a substituent R, and the substituent R may have 1 to 8 groups, which may be the same or different, and C is a monovalent group. 1 represents an integer of 1 to 8, n represents 2, 3, 4, m represents 0, 2, 4; Aromatic carboxylic acids as the ligand in the complex or salt, aromatic diols may be different even the same. Further, it may be a mixture of complex compounds having different numbers of n and m. From the viewpoint of improving the dispersibility of the zirconium complex or salt in the binder resin or improving the chargeability, the substituent R is preferably an alkyl group, alkenyl group, carboxyl group or hydroxyl group, and C is hydrogen, sodium or potassium. Ammonium and alkylammonium are preferred. Particularly preferred is a zirconium neutral complex having no counter ion and having a general formula of n = 2, which provides excellent environmental stability, excellent dispersibility in the binder resin, and good Durability is obtained.
[0127]
The zirconium complex or salt used in the present invention is a hexacoordinate or octacoordinate complex compound, and in the octacoordinate, a ligand-bridged binuclear complex compound is formed, and the hexacoordination in the formula is There is a complex compound. Typical structures of such complex compounds are exemplified by the following general chemical formulas (B-5) to (B-9). The following structures include those having no ligand L.
[0128]
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[0129]
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[0130]
Moreover, as a zirconium salt of aromatic carboxylic acid, the organic zirconium compound represented by general formula (B-10) and (B-11) is preferable.
[0131]
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[0132]
In general formulas (B-10) and (B-11), Ar is an alkyl group, aryl group, aralkyl group, cycloalkyl group, alkenyl group, alkoxy group, aryloxy group, hydroxyl group, acyloxy group, alkoxy as a substituent. A1 represents a monovalent aromatic residue which may have a carbonyl group, an aryloxycarbonyl group, an acyl group, a carboxyl group, a halogen, a nitro group, a cyano group, an amino group, an amide group, or a carbamoyl group. An anion, a halogen ion, a hydroxide ion, and a nitrate ion are represented, A2 represents a divalent anion, a sulfate ion, and a hydrogen phosphate ion, and n represents 1, 2, 3, and 4. The aromatic carboxylic acids and aromatic diols that are acid ions in each metal salt may be the same or different. Moreover, the mixture of the salt from which the number of n differs may be sufficient. From the viewpoint of improving the dispersibility of the metal salt in the binder resin or improving the chargeability, the aromatic residue is preferably a benzene ring, naphthalene ring, anthracene ring, or phenanthrene ring, and the substituent is an alkyl group, A carboxyl group, a hydroxyl group, and an acyloxy group are preferable. In general formula (B-10), n is preferably 4, and in general formula (B-11), n is preferably 2.
[0133]
Further preferred metal salts are zirconium salts represented by general formulas (B-12) and (B-13).
[0134]
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[0135]
In the general formulas (B-12) and (B-13), R represents hydrogen, alkyl group, aryl group, aralkyl group, cycloalkyl group, alkenyl group, alkoxy group, aryloxy group, hydroxyl group, alkoxycarbonyl group, aryl Represents an oxycarbonyl group, an acyloxy group, an acyl group, a carboxyl group, a halogen, a nitro group, an amino group, an amide group, a carbamoyl group, and may be linked to each other to form an aliphatic ring, an aromatic ring or a heterocyclic ring; In this case, the ring may have a substituent R. The substituent R may have 1 to 8 groups, which may be the same or different, and A1 is a monovalent anion, Represents a halogen ion, a hydroxide ion, or a nitrate ion, A2 represents a divalent anion, a sulfate ion, or a hydrogen phosphate ion, and 1 represents an integer of 1 to 8, It represents a 2, 3, 4. The aromatic carboxylic acids and aromatic diols that are acid ions in each metal salt may be the same or different. Moreover, the mixture of the salt from which the number of n differs may be sufficient. From the viewpoint of improving the dispersibility of the metal salt in the binder resin or improving the chargeability, the substituent is preferably an alkyl group, an alkenyl group, a carboxyl group, a hydroxyl group, or an acyloxy group. In the general formula (B-12), Those having n of 4 and those having n of 2 in the general formula (B-13) are preferred, providing excellent environmental stability, excellent dispersibility in the binder resin, and excellent durability. .
[0136]
The organic zirconium compound of the present invention is obtained by dissolving a zirconium compound such as chlorinated zirconium oxide, zirconium sulfate, or organic acid zirconium in water, an alcohol, or an alcohol aqueous solution, and adding an aromatic carboxylic acid, an aromatic diol, or an alkali metal salt thereof. Alternatively, it is synthesized by adding an aromatic carboxylic acid, an aromatic diol and an alkali agent. These organic zirconium compounds are recrystallized with an aqueous alcohol solution or the like and purified by washing with alcohol. In the case of complex salts, complex salts having various counter ions can be obtained by treating the product with a mineral acid, an alkali agent, and an amine agent. In this invention, what has multiple types, such as a hydrogen ion, an alkali metal ion, and an ammonium ion, is included in the counter ion of a zirconium complex salt.
[0137]
Specific examples of the organozirconium compounds used in the present invention will be given below, but here, the formulas are shown. Although what has coordinated 2-4 water molecules is also contained, description of a water molecule is abbreviate | omitted here. In addition, although counter ions include those having a plurality of types, only the most counter ions are described here.
[0138]
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[0139]
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[0140]
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[0141]
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[0142]
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[0143]
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[0144]
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[0145]
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[0146]
Examples of the colorant used in the present invention include the following yellow colorant, magenta colorant, and cyan colorant. As the black colorant, carbon black, magnetic substance, or yellow colorant / magenta colorant / cyan color shown below. What was mixed with the agent and was toned to black is used.
[0147]
The particle size of the carbon black used in the present invention is preferably 25 to 80 nm.
[0148]
When the particle size of the carbon black is smaller than 25 nm, since the primary particle size is fine, it is difficult to obtain sufficient dispersion and it is difficult to use it.
[0149]
If it is larger than 80 nm, there is a problem that even if it is dispersed well, only a low density image can be obtained or the toner consumption is increased due to insufficient coloring power as a toner.
[0150]
Regarding the particle size of the carbon black, it is more preferable that the particle size is 35 to 70 nm, and the charge polarity and the charge amount of the transfer residual toner by the charging member are more reliably and uniformly controlled, and the toner charge amount is stable. It is more advantageous in terms of properties and toner coloring power.
[0151]
The particle size of the carbon black in the toner in the present invention can be measured by taking an enlarged photograph with a transmission electron microscope.
[0152]
The DBP oil absorption of the carbon black used in the present invention is preferably 40 to 150 ml / 100 g.
[0153]
Carbon black with a short structure with a DBP oil absorption of less than 40 ml / 100 g tends to make the charge amount of the toner too low, and when it exceeds 150 ml / 100 g, it is difficult to obtain fine dispersion of carbon black due to its strong long structure.
[0154]
The DBP oil absorption is measured in accordance with ASTM method D2414-79.
[0155]
The carbon black used in the present invention has a nitrogen adsorption specific surface area of 100 m.²/ G or less and the volatile content is preferably 2% or less. The carbon black according to the present invention has a smaller specific surface area and less volatile content than those commonly used in toners.
[0156]
Carbon black having a small specific surface area and a small amount of volatile matter has the advantage of low polymerization inhibition because it has few polymerization inhibiting functional groups, and is also advantageous for uniform dispersion of carbon black in the toner.
[0157]
For nitrogen adsorption specific surface area, 100m²When it exceeds / g, polymerization inhibition tends to occur. Further, carbon black having a volatile content exceeding 2% is not suitable for use because a large number of polymerization-inhibiting functional groups exist on the surface.
[0158]
The nitrogen adsorption specific surface area is measured according to ASTM method D3037-78.
[0159]
When the toner is produced by a polymerization method, it is desirable to perform a step of predispersing carbon black together with the azo iron compound, zirconium complex or zirconium salt according to the present invention. Since carbon black is dispersed at a higher concentration, shearing force is easily applied, and the effect of improving dispersibility is increased.
[0160]
As the yellow colorant, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180, etc. are preferably used.
[0161]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.
[0162]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.
[0163]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant is selected from the viewpoints of hue, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner particles. The added amount of the colorant is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the resin component.
[0164]
When a magnetic material is used as the black colorant, it is preferable to use 40 to 150 parts by weight with respect to 100 parts by weight of the resin, unlike other colorants.
[0165]
In the present invention, a known charge control agent can be used in combination with the above-mentioned azo-based iron compound, zirconium complex or zirconium salt, and in particular, the charge control is fast and the charge control can stably maintain a constant charge amount. Agents are preferred. Further, when the toner particles are directly polymerized, a charge control agent having no polymerization inhibition and no solubilized product in an aqueous dispersion medium is preferable. Specific compounds include metal compounds of aromatic carboxylic acids such as salicylic acid, naphthoic acid and dicarboxylic acid as negative charge control agents; polymer compounds having a sulfonic acid or carboxylic acid group in the side chain; boron compounds; urea Compound; silicon compound; calixarene and the like. Examples of the positive charge control agent include a quaternary ammonium salt; a polymer compound having the quaternary ammonium salt in the side chain; a guanidine compound; an imidazole compound.
[0166]
However, in the present invention, it is not essential to add a charge control agent. When a two-component development method is used, frictional charging with a carrier is used, and when a non-magnetic one-component blade coating development method is used, It is not always necessary to include a charge control agent in the toner particles by actively utilizing frictional charging with the blade member or the sleeve member.
[0167]
Addition of inorganic fine powder to the toner of the present invention is a preferred embodiment for improving developability, transferability, charging stability, fluidity and durability. As the inorganic fine powder, known ones can be used, and it is particularly preferred to be selected from silica, alumina, titania or a double oxide thereof. Further, silica is more preferable. For example, the silica can be either a so-called dry method produced by vapor phase oxidation of silicon halide or alkoxide, or dry silica called fumed silica and so-called wet silica produced from alkoxide, water glass, etc. There are few silanol groups on the surface and in the silica fine powder, and Na₂O, SO_Three ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0168]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²/ G range gives good results, and 0.1 to 8 parts by weight of silica fine powder, preferably 0.5 to 5 parts by weight, more preferably more than 1.0 parts per 100 parts by weight of toner. It is particularly good to use up to 3.0 parts by weight.
[0169]
In addition, the inorganic fine powder used in the present invention has a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a functional group as necessary for the purpose of hydrophobization and chargeability control. It is possible and preferable to treat with a treating agent such as a silane coupling agent, an organic silicon compound, an organic titanium compound, etc. or in combination with various treating agents.
[0170]
The specific surface area was calculated according to the BET method by using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the sample surface and calculating the specific surface area using the BET multipoint method.
[0171]
In order to maintain a high charge amount and achieve a low consumption and a high transfer rate, the inorganic fine powder is more preferably treated with at least silicone oil.
[0172]
In the toner of the present invention, other additives, such as a lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder, cerium oxide powder, silicon carbide powder, titanium, within a range that does not have a substantial adverse effect. Abrasives such as strontium acid powder; fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents or conductivity-imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder; A small amount of polar organic fine particles and inorganic fine particles can be used as a developability improver.
[0173]
As a method for producing the toner of the present invention, a resin, a release agent composed of a low softening point substance, a colorant, a charge control agent, and the like are uniformly dispersed using a pressure kneader, an extruder, or a media dispersing machine. After colliding with a target under a mechanical or jet stream and pulverizing to a desired toner particle size (adding toner particle smoothing and spheronization steps if necessary), the particle size distribution is further passed through a classification step. In addition to a method for producing a toner by a pulverizing method for sharpening and squeezing toner, a method for obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945, Toner is produced directly using the suspension polymerization method described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842. Or a dispersion polymerization method in which a toner is produced directly using a water-based organic solvent that is soluble in monomers and insoluble in a polymer, or soap-free in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator. The toner can be produced by using an emulsion polymerization method typified by a polymerization method.
[0174]
In the method of producing toner using the pulverization method, it is difficult to keep the shape of the toner particles within a desired circularity frequency distribution range. In the melt spray method, a certain degree of circularity can be obtained. In addition, the particle size distribution of the obtained toner tends to be wide, and it is difficult to control the surface state of the toner. On the other hand, in the dispersion polymerization method, the obtained toner shows a very sharp particle size distribution, but the production equipment is used from the viewpoint of the processing of the waste solvent and the flammability of the solvent due to the narrow selection of materials to be used and the use of organic solvents. Complicated and complicated. An emulsion polymerization method typified by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform, but the used emulsifier and polymerization initiator terminals are present on the toner particle surface, and environmental characteristics are likely to deteriorate.
[0175]
In the present invention, it is important to control the frequency distribution of the circularity of the toner particles, and an emulsion polymerization method under normal pressure or under pressure can be obtained relatively easily to obtain a fine particle toner having a circle-equivalent number average diameter of 2 to 6 μm. Alternatively, a suspension polymerization method is used to form the polymer in advance using a medium, or a method in which the polymer is directly collided with a pressure impingement plate, and further, the obtained polymer is frozen in an aqueous system. In particular, an agglomeration method in which particles having salt folding or opposite surface charges are combined by considering conditions such as pH, and agglomeration and coalescence are particularly preferable. Furthermore, a seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized using a polymerization initiator can be suitably used in the present invention.
[0176]
When the direct polymerization method is used as a toner production method, the control of the toner particle circularity frequency distribution and particle size frequency distribution changes the kind and addition amount of a poorly water-soluble inorganic salt and a protective colloid dispersing agent. Predetermined toner particles can be obtained by controlling the method and mechanical device conditions (for example, the circumferential speed of the rotor, the number of passes, the stirring conditions such as the shape of the stirring blades and the shape of the container) or the solid content concentration in the aqueous solution. it can. Further, as described above, predetermined toner particles can be obtained also by adjusting the stirring conditions and the processing time of the conical dryer used for drying the toner particles.
[0177]
When the toner is produced by the direct polymerization method, examples of the polymerization initiator used include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1. Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide Peroxide-based polymerization initiators such as methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used. The amount of the polymerization initiator used varies depending on the desired degree of polymerization, but is generally 0.5 to 20% by weight based on the polymerizable monomer. The kind of the polymerization initiator is slightly different depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.
[0178]
In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor or the like may be further added and used.
[0179]
When a suspension polymerization method using a dispersion stabilizer is used as a toner production method, the dispersion stabilizer used is an inorganic compound such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, Examples thereof include magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and its salt, starch and the like. These can be used by dispersing in an aqueous phase. These dispersion stabilizers are preferably used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.
[0180]
When an inorganic compound is used as the dispersion stabilizer, a commercially available one may be used as it is, but in order to obtain fine particles, fine particles of the inorganic compound may be generated in a dispersion medium. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution may be mixed under high-speed stirring.
[0181]
For fine dispersion of these dispersion stabilizers, 0.001 to 0.1 parts by weight of a surfactant may be used in combination. This is to promote the intended action of the above dispersion stabilizer, such as sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate. , Calcium oleate and the like.
[0182]
When the direct polymerization method is used as a method for producing the toner used in the present invention, the following production method is possible.
[0183]
A release agent consisting of a low softening point substance, a colorant, a charge control agent, a polymerization initiator and other additives were added to the polymerizable monomer, and the mixture was uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser, or the like. The monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, the monomer composition is granulated by adjusting the stirring speed and stirring time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization is preferably carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving durability in the image forming method of the present invention, in order to remove the unreacted polymerizable monomer, by-products, etc., or After completion of the reaction, a part of the aqueous medium may be distilled off from the reaction system. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.
[0184]
Next, the image forming method of the present invention will be described below with reference to the accompanying drawings.
[0185]
Two-component development process:
FIG. 1 is a diagram schematically showing an image forming apparatus using a developing device using a two-component developer for magnetic brush development, which is used as an example of an embodiment of an image forming method of the present invention with reference to FIG. explain.
[0186]
In FIG. 1, a charging brush roller 5 serving as a charging means for the photosensitive member 2 (resistance is adjusted by dispersing carbon black in nylon fiber, the fiber thickness is 6 denier, the brush fiber length is 3 mm, and the brush density. Is 100,000 per square inch, rotating at a peripheral speed of 120% in the opposite direction to the rotation of the photosensitive member), contacting the photosensitive member 2 and applying a bias to charge, and exposure by laser light 6 (600 dpi, binary) Then, an electrostatic charge latent image is formed on the photoreceptor 2. A magnetic brush formed of a two-component developer having a toner and a magnetic carrier on the developer carrying member 1 of the developing device 15 is brought into contact with the photosensitive member 2, and an electrostatic charge latent image of the photosensitive member 2 is obtained by reversal development. Is developed to form a toner image.
[0187]
At least a direct current bias is applied to the developer carrying member 1 by a bias applying means (a development contrast is set to 500 V as a direct current component, and 1.8 kV is applied as an alternating current component).
[0188]
The toner image on the photoconductor 2 is transferred to the transfer material 4 being conveyed by a transfer corona charger 3 (not in contact with the photoconductor 2) as transfer means, and the toner image on the transfer material 4 is transferred to a heater. 8 is fixed to the transfer material 4 by a heating and pressure fixing means having a heating roller 7 including a pressure roller 8 and a pressure roller 9. As the photoconductor 2, the photoconductor of photoconductor production example 1 having a contact angle with water of 85 ° or more on the surface of the photoconductor was used. The transfer residual toner on the photoreceptor 2 after the transfer process does not go through the cleaning process. The photosensitive member 2 that has been neutralized by the erase exposure 11 is charged again by the charging brush roller 5, and an electrostatic charge latent image is formed by the exposure 6. The photosensitive member 2 having the transfer residual toner is subjected to the development of the electrostatic charge latent image by the magnetic brush on the developer carrier 1 and the recovery of the transfer residual toner to the developer carrier 1. The toner image on the photoconductor 2 after the development and cleaning process is transferred onto the transfer material 4 being conveyed by the transfer corona charger 3, and the photoconductor 2 after the transfer process is charged by the erase exposure 11 and charged. The brush roller 5 is charged again, and thereafter the same process is repeated.
[0189]
FIG. 2 is an enlarged view of the developing unit in FIG. In FIG. 2, the photosensitive member 2 is in contact with the magnetic brush formed of the two-component developer 20 on the developer carrier 1.
[0190]
The developer carrier 1 is made of a nonmagnetic material such as aluminum or SUS316. The developer carrier 1 has a substantially right half-periphery surface protruding into the developing unit 15 in a horizontally long opening formed in the container longitudinal direction on the left lower wall of the developer unit 15, and the left substantially half-periphery surface is exposed outside the container so as to be rotatable. The bearing is installed horizontally and is driven to rotate in the direction of the arrow.
[0191]
It is a fixed permanent magnet (magnet) as a fixed magnetic field generating means which is inserted into the developer carrier 1 and positioned and held in the position and orientation shown in the figure. Even when the developer carrier 1 is driven to rotate, the magnet 24 is shown in the figure. Fixed and held in position and orientation. The magnet 24 has N-pole magnetic poles 22, 25 and 26, and has five S-pole magnetic poles 21 and 23. The magnet 24 may be an electromagnet instead of a permanent magnet.
[0192]
Reference numeral 13 denotes a non-magnetic blade as a developer regulating member having a base fixed to the container side wall on the upper edge side of the developer supply opening in which the developer carrying member 1 is disposed. It is bent into a U shape.
[0193]
Reference numeral 14 denotes a magnetic carrier limiting member having an upper surface in contact with the lower surface side of a nonmagnetic blade (developer regulating member) 13 and having a front end surface as a developer guide surface. A portion constituted by the nonmagnetic blade 13 and the magnetic carrier return member 14 is a restricting portion.
[0194]
Reference numeral 20 denotes a developer layer having toner and a magnetic carrier. Reference numeral 16 denotes a non-magnetic toner.
[0195]
Reference numeral 27 denotes a toner supply roller that operates according to an output obtained by a toner density detection sensor (not shown). As the sensor, a developer volume detection method, a piezoelectric element, an inductance change detection element, an antenna method using an alternating bias, and a method for detecting optical density can be used. The nonmagnetic toner 16 is supplied by rotating or stopping the roller. The fresh developer replenished with the toner 16 is mixed and stirred while being conveyed by the developer conveying roller 17. Therefore, tribo is applied to the toner replenished during the conveyance. Reference numeral 18 denotes a notch at both ends in the longitudinal direction of the developing device, and the fresh developer conveyed by the screw 17 is transferred to the screw 19 at this portion.
[0196]
The N magnetic pole 26 is a transport pole. The collected developer after development is collected in a container, and the developer in the container is further transported to a regulating portion.
[0197]
In the vicinity of the N magnetic pole 26, the fresh developer conveyed by the screw 19 provided close to the developer carrier 1 and the recovered developer after development are exchanged.
[0198]
The distance d between the end of the nonmagnetic blade 13 and the surface of the developer carrying member 1 was 400 μm. A preferable setting range of d is 100 to 900 μm. If this distance is smaller than 100 μm, the carrier particles are clogged in the meantime, and the developer layer is likely to be uneven, and the developer necessary for good development cannot be applied, and only a developed image with a small density and unevenness can be obtained. It may not be possible. On the other hand, if the distance is greater than 900 μm, the amount of developer applied on the developer carrier 1 increases, and the predetermined developer layer thickness cannot be regulated, and magnetic particle adhesion to the latent image carrier increases. There is a tendency that the circulation of the developer and the development regulation by the developer limiting member 14 are weakened, and the toner tribo is insufficient and fogging easily occurs.
[0199]
It is preferable that the thickness of the developer layer on the developer carrier 1 is slightly larger than the opposing gap distance between the developer carrier 1 and the photoreceptor 2. This distance was set to 400 μm. Preferably, it is good to set to 50-800 micrometers.
[0200]
One-component development process:
With reference to FIG. 3, as another example of the embodiment of the image forming method of the present invention, an image forming method having a process cartridge from which a cleaning unit having a cleaning blade or the like is removed will be described with reference to a schematic view.
[0201]
The photosensitive member 36 is charged by a charging roller 31 that is a contact charging unit, and an image portion is exposed with a laser beam 40 to form an electrostatic charge latent image. The toner 30 in the developing device 32 is applied on the toner carrier 34 by the toner application roller 35 and the application blade 33, and the electrostatic charge latent image on the photosensitive member 36 is developed by the reversal development method with the toner on the toner carrier 34. A toner image is formed on the photoreceptor 36. At least a DC bias is applied to the toner carrier 34 by the bias applying means 41. The toner image on the photoreceptor 36 is transferred onto a transfer material 38 that is conveyed by a transfer roller 37 that is a transfer unit to which a bias is applied by a bias applying unit 42, and the toner image on the transfer material is heated by a heating roller. And a heat and pressure fixing means 43 having a pressure roller.
[0202]
As the photoconductor 36, the photoconductor of the photoconductor production example 1 having a contact angle with water of 85 ° or more on the surface of the photoconductor was used. The toner remaining on the photosensitive member 36 after the transfer process is transported to the charging roller 31 without passing through the cleaning process by a cleaning unit such as a blade cleaning unit. The photosensitive member 36 having the transfer residual toner is charged again by the charging roller 31, and an electrostatic latent image is formed by exposure with the laser beam 40 after charging. The photosensitive member 36 having the transfer residual toner is subjected to the development of the electrostatic charge latent image by the toner on the toner carrier 34 and the recovery of the transfer residual toner to the developer carrier 34. The toner image on the photoconductor 36 after the development and cleaning process is transferred onto the transfer material 38 conveyed by the transfer roller 37, and the photoconductor 36 after the transfer process is charged again by the charging roller 31, and so on. This process is repeated.
[0203]
In the reversal development method, as a preferable development condition for carrying out the simultaneous development cleaning, the dark portion potential (V_d) And light potential (V_l) And a DC bias (V) applied to the toner carrier._DC)_d-V_DC｜ ＞ ｜ V_l-V_DCIt is better to set so that the relationship | More preferably, | V_d-V_DCThe value of | is | V_l-V_DCIt is better to be at least 10V larger than the value of |.
[0204]
Image forming process using intermediate transfer belt:
FIG. 4 is a schematic explanatory view of a color image forming apparatus (copying machine or laser beam printer) using an intermediate transfer belt.
[0205]
Reference numeral 51 denotes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as a first image carrier, which is rotationally driven in the direction of an arrow at a predetermined peripheral speed (process speed).
[0206]
In the rotation process, the photosensitive drum 51 is uniformly charged to a predetermined polarity and potential by a primary charger 52, and then subjected to exposure 53 by an image exposure unit (not shown). In this way, an electrostatic latent image corresponding to the first color component image (for example, yellow color component image) of the target color image is formed.
[0207]
Next, the electrostatic latent image is developed into a yellow component image which is the first color by the first developing device (yellow color developing device 71). At this time, the second to fourth developing units, that is, the magenta developing unit 72, the cyan developing unit 73, and the black developing unit 74 are not operated and do not act on the photosensitive drum 51. The yellow component image of the color is not affected by the second to fourth developing units.
[0208]
The intermediate transfer belt 77 is driven to rotate in the direction of the arrow at the same peripheral speed as that of the photosensitive drum 51.
[0209]
In the process in which the yellow component image of the first color formed on the photosensitive drum 51 passes through the nip portion between the photosensitive drum 51 and the intermediate transfer belt 77, the intermediate transfer belt is supplied from the bias power source 78 via the primary transfer roller 62. The image is sequentially transferred (primary transfer) to the outer peripheral surface of the intermediate transfer belt 77 by the electric field formed by the primary transfer bias applied to 77.
[0210]
The surface of the photosensitive drum 51 after the transfer of the first color yellow toner image corresponding to the intermediate transfer belt 77 is cleaned by a developing and cleaning method using a toner carrier of the yellow developing unit 71.
[0211]
Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer belt 77, and a composite color corresponding to the target color image is obtained. A toner image is formed.
[0212]
Reference numeral 63 denotes a secondary transfer roller, which is supported in parallel with the secondary transfer counter roller 64 and arranged in a state in which it can be separated from the lower surface portion of the intermediate transfer belt 77.
[0213]
A primary transfer bias for transferring the toner image from the photosensitive drum 51 to the intermediate transfer belt 77 is applied from a bias power source 78 with a polarity opposite to that of the toner. The applied voltage is, for example, in the range of +100 V to +2 kV.
[0214]
In the primary transfer process of the first to third color toner images from the photosensitive drum 51 to the intermediate transfer belt 77, the secondary transfer roller 63 and the cleaning device 54 can be separated from the intermediate transfer belt 77.
[0215]
The full-color image transferred on the intermediate transfer belt 77 is contacted by the secondary transfer roller 63 with the intermediate transfer belt 77, and a predetermined portion is contacted between the sheet feeding roller 80 and the intermediate transfer belt 70 and the secondary transfer roller 63. At this timing, the transfer material P as the second image carrier is fed, and the secondary transfer bias is applied from the bias power source 76 to the secondary transfer roller 63 to be secondarily transferred to the transfer material P. The transfer material P onto which the toner image has been transferred is introduced into the fixing device 75 and fixed by heating.
[0216]
After the image transfer to the transfer material P is completed, the intermediate transfer belt 77 is brought into contact with the cleaning device 54 for residual toner, and the intermediate transfer belt 77 is cleaned.
[0217]
By the way, in the present invention, it is preferable to impart releasability to the surface of the photoconductor, and the contact angle of water on the surface of the photoconductor is preferably 85 degrees or more. Due to this effect, the amount of toner remaining in the transfer can be remarkably reduced, there is almost no light shielding by the toner remaining in the transfer, and a negative ghost image can be essentially prevented, and the recovery efficiency of the toner remaining in the transfer in the development area can be improved during development. Improve and prevent positive ghost images.
[0218]
Here, the generation mechanism of the ghost image will be described.
[0219]
The problem of light shielding by transfer residual toner is especially problematic when the surface of the photoconductor is used repeatedly for a single transfer material, that is, when the length of the entire circumference of the photoconductor is shorter than the length of the transfer material in the direction of travel. Because the transfer residual toner must be charged, exposed, and developed in a state where the residual toner is present on the photosensitive member, the potential on the surface of the photosensitive member where the residual transfer toner exists is not sufficiently lowered and the development contrast is insufficient. Therefore, the reversal development appears on the image as a negative ghost having a lower density than the surroundings.
[0220]
On the other hand, if the cleaning effect of the transfer residual toner is insufficient at the time of development, the toner is developed on the surface of the photoreceptor where the transfer residual toner is present, so that the density is higher than the surroundings and a positive ghost is generated.
[0221]
In the configuration of the present invention, the ghost image as described above can be essentially prevented.
[0222]
The present invention is also effective when the surface of the photoreceptor is mainly composed of a polymer binder. For example, when a protective film mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or as a charge transport layer of a function-separated organic photoreceptor, a surface layer composed of a charge transport material and a resin is provided. In some cases, the protective layer as described above may be further provided thereon. As a means for imparting releasability to such a surface layer,
(1) Use a resin having a low surface energy as the resin itself constituting the film.
(2) Add additives that impart water repellency and lipophilicity.
(3) Disperse the material having high releasability in powder form.
Etc. Examples of (1) are achieved by introducing fluorine-containing groups, silicone-containing groups, etc. into the resin structure. As (2), a surfactant or the like may be used as an additive. Examples of (3) include compounds containing fluorine atoms, that is, polytetrafluoroethylene, polyvinylidene fluoride, carbon fluoride, and the like.
[0223]
By these means, the contact angle with respect to water on the surface of the photoreceptor can be set to 85 degrees or more. If it is less than 85 degrees, the toner and the toner carrier are likely to deteriorate due to durability. Further, it is more preferable that the contact angle of water on the surface of the photoreceptor is 90 degrees or more.
[0224]
Of these, polytetrafluoroethylene is particularly preferred. In the present invention, it is preferable to disperse the releasable powder such as the fluorine-containing resin (3) in the outermost surface layer.
[0225]
In order to contain these powders on the surface, a layer in which the powder is dispersed in a binder resin is provided on the outermost surface of the photoreceptor, or an organic photoreceptor that is originally composed mainly of a resin. For example, the powder may be dispersed in the uppermost layer without newly providing a surface layer.
[0226]
The amount of the powder added to the surface layer is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, based on the total weight of the surface layer. If the amount is less than 1% by weight, the residual toner is not sufficiently reduced, and the cleaning efficiency of the residual toner is not sufficient, and the ghost prevention effect is insufficient. If the amount exceeds 60% by weight, the strength of the film decreases. Or the amount of light incident on the photoreceptor is remarkably reduced. The particle diameter of the powder is 1 μm or less, preferably 0.5 μm or less from the viewpoint of image quality. When it is larger than 1 μm, the line breakage is deteriorated due to scattering of incident light, and it cannot be put into practical use.
[0227]
The present invention is particularly effective when the charging unit is a direct charging method in which a charging member is brought into contact with the photosensitive member. That is, if there is a large amount of unrecovered toner after cleaning, it adheres to the direct charging member, which is a subsequent process, and causes charging failure. Therefore, the amount of unrecovered toner is smaller than that of corona discharge in which the charging unit does not come into contact with the photoreceptor, and it is necessary to make it difficult to adhere.
[0228]
One preferred embodiment of the photoreceptor used in the present invention will be described below.
[0229]
Examples of the conductive substrate include metals such as aluminum and stainless steel, plastics having a coating layer made of aluminum alloy, indium oxide-tin oxide alloy, paper / plastic impregnated with conductive particles, plastics having a conductive polymer, etc. Cylindrical cylinders and films are used.
[0230]
On these conductive substrates, the purpose is to improve the adhesion of the photosensitive layer, improve coating properties, protect the substrate, cover defects on the substrate, improve charge injection from the substrate, and protect against electrical breakdown of the photosensitive layer. An undercoat layer may be provided. Undercoat layer is polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymer nylon, glue, gelatin, polyurethane -It is made of a material such as aluminum oxide. The film thickness is usually about 0.1 to 10 μm, preferably about 0.1 to 3 μm.
[0231]
The charge generation layer is composed of azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium dyes, pyrylium salts, thiopyrylium salts, triphenylmethane dyes, selenium, amorphous silicon, etc. It is formed by dispersing a charge generating substance such as an inorganic substance in an appropriate binder and coating or vapor deposition. Of these, phthalocyanine pigments are preferred for adjusting the sensitivity of the photoreceptor to a sensitivity suitable for the present invention. The binder can be selected from a wide range of binder resins such as polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin, etc. Is mentioned. The amount of the binder contained in the charge generation layer is selected to be 80% by weight or less, preferably 0 to 40% by weight. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.05 to 2 μm.
[0232]
The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transport layer is formed by dissolving a charge transport material in a solvent together with a binder resin as required, and coating, and the film thickness is generally 5 to 40 μm. Examples of charge transport materials include polycyclic aromatic compounds having structures such as biphenylene, anthracene, pyrene, phenanthrene in the main chain or side chain, nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole, pyrazoline, hydrazone compounds, Examples include styryl compounds, selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide.
[0233]
As binder resins for dispersing these charge transport materials, resins such as polycarbonate resins, polyester resins, polymethacrylates, polystyrene resins, acrylic resins, polyamide resins, and organic photoconductive materials such as poly-N-vinylcarbazole and polyvinylanthracene are used. Include a functional polymer.
[0234]
Moreover, you may provide a protective layer as a surface layer. As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent for these resins may be used alone or in combination of two or more.
[0235]
Moreover, you may disperse | distribute electroconductive fine particles in resin of a protective layer. Examples of the conductive fine particles include metals and metal oxides, preferably zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide coated titanium oxide, tin coated indium oxide, There are ultrafine particles such as antimony-coated tin oxide and zirconium oxide. These may be used alone or in combination of two or more. In general, when particles are dispersed in a protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of incident light in order to prevent scattering of incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The conductive and insulating particles preferably have a particle size of 0.5 μm or less. Moreover, 2 to 90 weight% is preferable with respect to the protective layer total weight, and, as for content in a protective layer, 5 to 80 weight% is more preferable. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.
[0236]
The surface layer can be applied by spray coating, beam coating or penetration (dipping) coating of the resin dispersion.
[0237]
The developing process used in the present invention is very suitable particularly when the reversal developing method is used, since the developer and the surface of the photoreceptor are in contact with each other. When the two-component magnetic brush developing method is used, as the carrier, ferrite, magnetite, iron powder, or those coated with acrylic resin, silicone resin, fluorine resin or the like are used. At this time, at the time of development or blank time before and after development, a bias of a direct current or alternating current component is applied to control the potential so that the development and the remaining toner on the photoreceptor can be collected. At this time, the direct current component is located between the light portion potential and the dark portion potential.
[0238]
In the case of a one-component developer, a method of using an elastic roller as a toner carrier, coating the toner on the surface of the elastic roller, and bringing the toner into contact with the surface of the photoreceptor is also used. At this time, it is important that the toner is in contact with the surface of the photoreceptor, regardless of whether the toner is magnetic or non-magnetic. At this time, since cleaning is performed together with development by an electric field acting between the photosensitive member and the elastic roller facing the surface of the photosensitive member via the toner, the surface of the elastic roller or the vicinity of the surface has a potential, and the surface of the photosensitive member and the toner are carried. There is a need to have an electric field between the surfaces. Therefore, it is possible to use a method in which the elastic rubber of the elastic roller is resistance-controlled in the middle resistance region to keep the electric field while preventing conduction with the surface of the photoreceptor, or a method of providing a thin insulating layer on the surface layer of the conductive roller. . Furthermore, a conductive resin sleeve in which the side facing the surface of the photoreceptor is covered with an insulating material on the conductive roller, or a conductive layer is provided on the side not facing the photoreceptor with the insulating sleeve is also possible. Further, a configuration in which a rigid roller is used as the toner carrying member and the photosensitive member is flexible such as a belt is possible. The resistance of the developing roller as the toner carrier is 10²-10⁹A range of Ω · cm is preferred.
[0239]
When the one-component contact development method is used, the surface of the roller carrying the toner may be rotated in the same direction as the circumferential speed of the photosensitive member, or may be rotated in the opposite direction. When the rotation is in the same direction, the peripheral speed ratio is preferably 100% or more with respect to the peripheral speed of the photoreceptor. If it is less than 100%, the image quality is poor. The higher the peripheral speed ratio, the more toner is supplied to the development site, the more frequently the toner is desorbed from the latent image, and the unnecessary parts are scraped off and applied to the necessary parts. Thus, an image faithful to the latent image can be obtained. From the standpoint of development and cleaning, it is also possible to expect the effect that the transfer residual toner adhered on the photoconductor is physically peeled off from the surface of the photoconductor by the peripheral speed difference and recovered by the electric field. The higher the value is, the more convenient it is for collecting the residual toner. Specifically, the moving speed of the toner carrying member surface is preferably 1.05 to 3.0 times the moving speed of the photosensitive member surface.
[0240]
The contact transfer process applicable to the image forming method of the present invention will be specifically described below.
[0241]
In the contact transfer process, the developed image is electrostatically transferred to the transfer material while contacting the transfer means via the photosensitive member and the transfer material. The contact pressure of the transfer means is a linear pressure of 2.9 N / m. It is preferably (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more. If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because transfer of the transfer material and transfer failure are likely to occur.
[0242]
In addition, as a transfer means in the contact transfer process, an apparatus having a transfer roller or a transfer belt is used. The transfer roller is composed of at least a metal core and a conductive elastic layer. The conductive elastic layer has a volume resistance of 10 such as urethane or EPDM in which a conductive material such as carbon is dispersed.⁹-10^TenIt is made of an elastic body of about Ωcm.
[0243]
The present invention is particularly effectively used in an image forming apparatus in which the surface of the photoreceptor is an organic compound. That is, when the organic compound forms the surface layer of the photoconductor, it has better adhesion to the binder resin contained in the toner particles than other photoconductors using inorganic materials, and transferability is further reduced. This is because they tend to.
[0244]
Examples of the surface material of the photoreceptor according to the present invention include, but are not limited to, silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. In other words, other monomers or copolymers and blends between the aforementioned binder resins can also be used.
[0245]
In addition, the present invention is particularly effectively used for an image forming apparatus having a small-sized photoconductor having a diameter of 50 mm or less. That is, in the case of a small-diameter photoconductor, the curvature with respect to the same linear pressure is large, and pressure concentration tends to occur at the contact portion. Although the belt photoreceptor is considered to have the same phenomenon, the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer portion.
[0246]
Furthermore, since the toner according to the present invention has a high charging ability, it is desirable to control the total charge amount of the toner during development, and the surface of the toner carrier according to the present invention is dispersed with conductive fine particles and / or lubricant. It is preferable that the resin layer is covered.
[0247]
As a charging method, a known corona charging method called corotron or scorotron is used, and a method using a pin electrode can also be used. The direct charging method can also be used in the same manner.
[0248]
Further, in the present invention, it is preferable from the viewpoint of environmental protection that the charging member is in contact with the photoreceptor so that ozone is not generated.
[0249]
Preferred process conditions when using a charging roller include a contact pressure of the roller of 5 to 500 g / cm, aligning the polarity of the residual toner to the same polarity as the charging polarity of the photoconductor, and collecting at the time of development. For the sake of simplicity, it is preferable to apply a DC voltage, but when using a DC voltage superimposed with an AC voltage, the peak interval is less than 2 × Vth (V) [Vth; discharge start voltage (V) when DC is applied] It is preferable to superimpose an AC voltage having a voltage on the DC voltage.
[0250]
Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means are effective in that a high voltage is not required and generation of ozone is reduced.
[0251]
As the contact charging member, in the case of a roller or a blade, a metal such as iron, copper or stainless steel, a carbon dispersion resin, a metal or a metal oxide dispersion resin, or the like is used as a conductive substrate. The shape can be used. For example, the elastic roller is composed of a conductive substrate provided with an elastic layer, a conductive layer, and a resistance layer. The roller elastic layer includes chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber. , Rubber or sponge such as butyl rubber, styrene-butadiene thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, ethylene-vinyl acetate thermoplastic elastomer, etc. As for volume resistivity 10⁷Ω · cm or less, preferably 10⁶Ω · cm or less. For example, metal vapor deposition film, conductive particle dispersion resin, conductive resin, etc. are used. Specific examples include vapor deposition films of aluminum, indium, nickel, copper, iron, etc., and examples of conductive particle dispersion resin include carbon. And those obtained by dispersing conductive particles such as aluminum, nickel, and titanium oxide in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethyl methacrylate. Examples of the conductive resin include quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline, polyvinyl pyrrole, polydiacetylene, and polyethyleneimine. For example, the resistive layer has a volume resistivity of 10⁶-10¹²A layer of Ω · cm, and a semiconductive resin, a conductive particle-dispersed insulating resin, or the like can be used. As the semiconductive resin, resins such as ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymerized nylon, polyvinyl hydrin, and casein are used. Examples of conductive particle-dispersed resins include small amounts of conductive particles such as carbon, aluminum, indium oxide, and titanium oxide in insulating resins such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethyl methacrylate. Examples include dispersed ones.
[0252]
As the charging member, a brush whose resistance is adjusted by dispersing a conductive material in commonly used fibers is used. As the fiber, generally known fiber can be used, and examples thereof include nylon, acrylic, rayon, polycarbonate, polyester and the like. As the conductive material, generally known conductive materials can also be used, and metals such as copper, nickel, iron, aluminum, gold and silver, or iron oxide, zinc oxide, tin oxide, antimony oxide and titanium oxide. Metal oxides such as carbon black, and conductive powder such as carbon black. These conductive powders may be subjected to surface treatment for the purpose of hydrophobization and resistance adjustment as necessary. In use, it is selected in consideration of dispersibility with fibers and productivity. As the shape of the brush, the fiber thickness is 1 to 20 denier (fiber diameter of about 10 to 500 μm), the brush fiber length is 1 to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1 1.5 x 10 per square meter⁷~ 4.5 × 10⁸About this) is preferably used.
[0253]
【Example】
Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited thereto.
[0254]
The contents of the wax components used in the present invention are summarized in Table 1 together with the DSC measurement results.
[0255]
[Table 1]

[0256]
That is, <A> higher fatty acid ester wax, <B> higher alcohol wax, <C> wax obtained by fractionation from polyalkylene synthesized by Fischer-Tropsch method, <D> obtained by fractionation from polyalkylene synthesized by Age method Wax obtained by oxidative decomposition of polypropylene (for the toner of the present invention), and <a> and <b> wax obtained by oxidative decomposition of polyethylene (for comparative toner). .
[0257]
[Toner Production Examples and Comparative Production Examples]
Production examples and comparative production examples of the toner of the present invention will be described.
[0258]
Toner production example 1
650 g of ion-exchanged water and 0.1 mol / liter-Na in a 4-liter flask for 2 liters equipped with a high-speed stirring device TK type homomixer (made by Tokushu Kika Kogyo Co., Ltd.)_ThreePO_Four500 g of an aqueous solution was added, the rotation speed was adjusted to 12000 rpm, and the mixture was heated to 70 ° C. Here 1.0 mol / liter-CaCl₂70 parts by weight of an aqueous solution is gradually added, and a minute hardly water-soluble dispersion stabilizer Ca_Three(PO_Four)₂An aqueous dispersion medium containing was prepared.
[0259]
On the other hand, as dispersoid,
・ 77 parts by weight of styrene
・ 23 parts by weight of 2-ethylhexyl acrylate
・ 0.2 parts by weight of divinylbenzene
・ Carbon black (particle size = 45 nm) 8 parts by weight
・ Polycarbonate resin (peak molecular weight = 7000) 5 parts by weight
・ Azo-based iron complex compound (A-1) 2 parts by weight
-10 parts by weight of the wax component <A> in Table 1 above
After dispersing the mixture consisting of 3 for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.), 10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was added to obtain a polymerizable monomer composition. Prepared.
[0260]
Next, the polymerizable monomer composition is put into the aqueous dispersion medium, and N₂While maintaining the rotation speed of the high-speed stirrer at 12000 rpm in the atmosphere, the mixture was stirred for 15 minutes to granulate the polymerizable monomer composition. Thereafter, the stirrer was changed to a propeller stirring blade and held at the same temperature for 5 hours while stirring at 50 rpm, and further heated to 80 ° C. and held for 10 hours to complete the polymerization.
[0261]
After completion of the polymerization, the residual monomer was distilled off under reduced pressure by heating at 80 ° C./47 kPa (350 Torr), the suspension was cooled, and then diluted hydrochloric acid was added to remove the dispersion stabilizer. Further, after washing with water several times, polymer particles are stirred with a spiral ribbon rotor blade at 45 ° C./1.3 kPa (10 Torr) under reduced pressure by using a cone-type ribbon dryer (Okawara Seisakusho). The spheroidization treatment and the drying treatment were performed for 6 hours to obtain polymer particles (A).
[0262]
The polymer particles (A) have a circle-equivalent number average diameter of 3.7 μm, an average circularity in a circularity frequency distribution of 0.985, a circularity standard deviation of 0.030, and a molecular weight distribution by GPC. The peak molecular weight was 12,000 and Mw / Mn was 13.
[0263]
The volatile components remaining in the polymer particles (A) were 40 ppm for the styrene monomer and 0 ppm (not detected) for the 2-ethylhexyl acrylate monomer. Further, when the dispersion state of the wax component was observed by TEM, it was substantially spherical and dispersed in the binder resin as shown in the schematic diagram of FIG.
[0264]
100 parts by weight of the above polymer particles (A) and hydrophobic oil-treated silica fine powder (BET; 200 m²/ G) 2 parts by weight were dry-mixed with a Henschel mixer (Mitsui Metals Co., Ltd.) to obtain the toner (A) of the present invention, and then 5 parts by weight of the toner (A) and a resin-coated magnetic ferrite carrier (average particle diameter) 40 μm) and 95 parts by weight were mixed to prepare a two-component developer (A) for magnetic brush development.
[0265]
Toner Production Examples 2 to 5
Change the type and amount of wax component, the type and amount of polar resin, and change the temperature and pressure reduction and processing time when the residual monomer is distilled off, and the set temperature and stirring conditions and processing time of the conical ribbon dryer. Thus, after obtaining the polymer particles (B) to (E) in the same manner as in the toner production example 1 except that the particle size distribution and shape of the particles and the amount of the residual monomer were controlled, Toners (B) to (E) and developers (B) to (E) were prepared.
[0266]
Table 2 shows the types and addition amounts of waxes and the types and addition amounts of polar resins in each production example.
[0267]
Comparative toner production example 1
Production of toner except that instead of the wax component <A> and the polycarbonate resin, the wax component <a> in Table 1 and a saturated polyester resin (condensation polymer of propoxylated bisphenol A and terephthalic acid, peak molecular weight = 7000) are used. After obtaining comparative polymer particles (a) in the same manner as in Example 1, a comparative toner (a) and further a comparative developer (a) were prepared.
[0268]

[0269]
The above mixture is melt kneaded with a twin screw extruder, the cooled kneaded product is coarsely pulverized with a hammer mill, the coarsely pulverized product is finely pulverized with a jet mill, and the resulting finely pulverized product is classified to obtain a classified powder (b) It was. Using the classified powder (b), a comparative toner (b) and further a comparative developer (b) were prepared in the same manner as in Toner Production Example 1.
[0270]
In the classified powder (b), 182 ppm of styrene monomer derived from the binder resin and 6 ppm of 2-ethylhexyl acrylate monomer remained as volatile components, and the wax component was finely dispersed.
[0271]
Table 2 summarizes the properties of the polymer particles (A) to (E) obtained above, the comparative polymer particles (a), and the classified powder (b).
[0272]
[Table 2]

[0273]
Toner Production Example 6
・ 75 parts by weight of styrene
・ 25 parts by weight of 2-ethylhexyl acrylate
・ 0.3 parts by weight of divinylbenzene
・ Polycarbonate resin (peak molecular weight = 3000) 5 parts by weight
・ Zirconium compound (B-15) 2 parts by weight
-10 parts by weight of the wax component <C> in Table 1 above
Polymer particles (F) were obtained in the same manner as in Toner Production Example 1 except that the polymerizable monomer composition comprising the above mixture was used as a dispersoid.
[0274]
100 parts by weight of the polymer particles (F) and a hydrophobic oil-treated silica fine powder (BET: 50 m²/ G) 1.5 parts by weight, hydrophobic oil-treated titanium oxide fine powder (BET: 200 m²/ G) 0.5 part by weight was dry-mixed with a Henschel mixer (manufactured by Mitsui Kinzoku Co., Ltd.) to obtain the toner (F) of the present invention.
[0275]
Toner Production Examples 7-9 and Comparative Production Examples 3-6
While changing the type and amount of colorant, zirconium compound, and polar resin, the temperature and pressure reduction degree of the residual monomer and the treatment time, the set temperature of the conical ribbon dryer, the stirring conditions and the treatment time The toner of the present invention was obtained after obtaining the polymer particles (G) to (I) and the comparative polymer particles (c) to (f) in the same manner as in the toner production example 1 except that the toner particles were changed. (G) to (I) and comparative toners (c) to (f) were prepared.
[0276]
The colorant, zirconium compound, polar resin type and amount added in each production example, and various properties of the obtained polymer particles (F) to (I) and comparative polymer particles (c) to (f). Table 3 summarizes.
[0277]
[Table 3]

[0278]
[Production example of electrostatic latent image carrier]
An example of producing a photosensitive drum as an electrostatic latent image carrier used in the image forming method of the present invention will be described.
[0279]
Photosensitive drum production example 1
A photoconductor drum 1 was manufactured by using an aluminum cylinder having a diameter of 30 mm and a length of 254 mm as a base, and laminating layers having the following configurations by sequential dip coating.
[0280]
(1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powders dispersed in a phenolic resin. Film thickness 15 μm.
[0281]
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
[0282]
(3) Charge generation layer: Mainly composed of an azo pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
[0283]
(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by the Ostwald viscosity method) at a weight ratio of 8:10, and polytetrafluoroethylene powder ( 10% by weight with respect to the total solid content was added and dispersed uniformly. Film thickness 25 μm.
[0284]
The contact angle of water on the surface of the obtained photosensitive drum 1 with respect to water was 95 degrees.
[0285]
The contact angle was measured using pure water, and the device used was Kyowa Interface Science Co., Ltd., contact angle meter CA-DS type.
[0286]
Photoconductor drum production example 2
Except that the polytetrafluoroethylene powder was not added to the charge transport layer, a charge transport layer having a film thickness of 25 μm was formed in the same manner as in Production Example 1 of the photoreceptor drum to produce the photoreceptor drum 2. did. The contact angle of water on the surface of the obtained photosensitive drum 2 with respect to water was 79 degrees.
[0287]
Example 1
Images were formed using the image forming apparatus having the two-component development process shown in FIGS.
[0288]
The surface of the electrostatic latent image carrier 2 was set to move at a rotational peripheral speed of 180 mm / sec, and the developer (A) was used as the developer.
[0289]
A 1000-sheet printout test was performed while replenishing toner, and image evaluation was performed. As a result, both image density and dot reproducibility were good, and image defects such as image contamination, fogging, scattering, and voids did not occur. High-quality images were obtained. Further, the surface of the photoreceptor and the developing roller was observed, but there was no fusion or damage, and the amount of toner attached to the charging roller was slight, so that it was not necessary to replace it.
[0290]
The evaluation results are shown in Table 4.
[0291]
  Example 2, Reference Examples 3-5
  Evaluation was performed in the same manner as in Example 1 except that the developers (B) to (E) were used as the developers. The results were generally good as shown in Table 4.
[0292]
Comparative Examples 1 and 2
Evaluation was conducted in the same manner as in Example 1 except that comparative developers (a) and (b) were used as developers. As a result, as shown in Table 4, the charging member was significantly contaminated with toner, resulting in image defects due to charging failure.
[0293]
[Table 4]

[0294]
Example 6
FIG. 3 is a schematic explanatory view of a cross section of an image forming apparatus having a one-component development process applied to this embodiment. A commercially available laser printer LBP-EX (manufactured by Canon Inc.) is remodeled and reconfigured. It was. That is, the surface of the electrostatic latent image carrier 36 moves in the direction of the arrow at a rotational peripheral speed of 96 mm / sec (corresponding to a printout speed of 16 sheets (A4 size) / min). The cleaning rubber blade in the process cartridge was removed, and the charging method of the apparatus was contact charging in contact with the rubber roller 31, and the applied voltage was a DC component (-1400 V). An electrostatic latent image was formed by exposure (600 dpi) with laser light 40.
[0295]
Next, the development part in the process cartridge was modified. Medium resistance rubber roller (16mm, hardness ASKER C45 degree, resistance 10) made of urethane foam instead of stainless steel sleeve as toner carrier^FiveΩ · cm) to contact the electrostatic latent image carrier 36. The moving direction of the surface of the toner carrying member 34 is the same as the moving direction of the surface of the photosensitive member, and is driven so as to be 130% with respect to the circumferential speed of the photosensitive member.
[0296]
As a means for applying toner to the toner carrier 34, an application roller 35 is provided in contact with the toner carrier 34 at the developing portion. Further, a stainless steel blade 33 coated with resin was attached to control the coat layer of the toner on the toner carrier 34.
[0297]
As the electrostatic latent image carrier 36, the photosensitive member (1) produced in the photosensitive drum production example 1 is used, the toner (A) is used as the toner, and the process conditions are set so as to satisfy the following development conditions. did.
Photoconductor dark part potential: -800V
Photoreceptor bright part potential: -150V
Development bias: -450V (DC component only)
[0298]
When the image was evaluated by printing out 1000 sheets while replenishing the toner, both the image density and the dot reproducibility were good, and image defects such as image smudge, fog, splatter, void and ghost did not occur. , Got the same image quality as the initial. Further, the surface of the photoreceptor and the developing roller was observed, but there was no fusion or damage, and the amount of toner attached to the charging roller was slight, so that it was not necessary to replace it.
[0299]
The evaluation results are shown in Table 5.
[0300]
  Example 7
  The rotational peripheral speed of the surface of the electrostatic latent image carrier 36 of the image forming apparatus used in Example 6 is 144 mm / sec (corresponding to a printout speed of 20 sheets (A4 size) / min), and the developer container 32 has Example 1 except that a sponge roller having a single layer structure is used as the toner application roller 35 and the toner application roller 35 is changed so as to apply a bias voltage from a bias application means (not shown).6LikePictureAn image was formed and evaluated.
[0301]
At the time of development, only a direct current component of −300 V was applied to the developing roller 34 as a developing bias voltage, and only a direct current component of −450 V was applied to the toner application roller 35 as a bias voltage.
[0302]
As the printout speed was increased, excellent images were obtained despite the fact that the conditions were severe with respect to uniform charging of the photoreceptor, toner charge control, and toner contamination on the charging roller. . Further, although the toner adhesion amount on the charging roller increased, the matching with the image forming apparatus was generally good.
[0303]
  Example 8
  Example except that the photoconductor (2) produced in Photoconductor drum production example 2 is used.6A printout test was conducted in the same manner as described above. A slight ghost is generated in the obtained image, and the results are shown in Table 5.6Although it was a little inferior to, it was generally good.
[0304]
  Example 9, Reference Examples 10-12
  A printout test was conducted in the same manner as in Example 6 except that toners (B) to (E) were used as toners. The results were generally good as shown in Table 5.
[0305]
Comparative Examples 3 and 4
Evaluation was performed in the same manner as in Example 6 except that comparative toners (a) and (b) were used as toners. As a result, as shown in Table 5, the toner was remarkably contaminated with the charging member, resulting in an image failure due to charging failure.
[0306]
[Table 5]

[0307]
Example 13
Image formation was performed using an image forming apparatus having a transfer belt shown in FIG.
[0308]
In the image forming apparatus, a developing and cleaning method is performed by a toner carrier as a first cleaning unit, and an intermediate transfer is performed as a cleaning unit for removing toner remaining on the surface of the intermediate transfer member after the second transfer step. A cleaner having a cleaning member in contact with the body surface is provided on the downstream side of the second transfer unit and on the upstream side of the first transfer unit.
[0309]
As the developing device 57, the one having the developing device 32 shown in FIG. 3 was used. The toner remaining on the surface of the photosensitive drum after the first transfer is developed only for the toner existing in the non-image area at the developing portion after development after the charging polarity is made negative by applying a charging bias at the charging portion. It was configured to collect in the vessel.
[0310]
In the developing device 8, a medium resistance rubber roller (16 mm) made of silicone rubber, the resistance of which is adjusted by dispersing carbon black, is used as the toner carrier 9 and is in contact with the photoconductor. The moving direction and the rotational peripheral speed of the surface of the toner carrying member 9 are the same in the contact portion with the surface of the photosensitive member, and are driven so as to be 150% of the photosensitive member rotational peripheral speed. That is, the peripheral speed of the toner carrier is 120 mm / s, and the relative speed with respect to the surface of the photoreceptor is 80 mm / s.
[0311]
As a means for applying the toner to the toner carrier, a sponge roller having a single layer structure was provided as the application roller 12 and brought into contact with the toner carrier. At the contact portion, the toner was applied onto the toner carrier by rotating so that the moving direction of the surface of the application roller 12 was moved in the direction opposite to the moving direction of the toner carrier. Further, a stainless steel blade 16 coated with resin was attached to control the coat layer of the toner on the toner carrier.
[0312]
As the photoreceptor, the photoreceptor (1) produced in the photoreceptor production example 1 was used, and the toner (A) was used as the toner, and the image forming conditions were set so as to satisfy the following development conditions and transfer conditions.
Photoconductor dark part potential: -700V
Photoreceptor bright part potential: -150V
Development bias applied to development roller: -450V (DC component only)
Bias applied to toner application roller: -300V (DC component only)
Transfer bias applied to the intermediate transfer member in the first transfer process: 350 V (only DC component)
Transfer bias applied to the transfer roller in the second transfer step: 1100 V (DC component only)
[0313]
The toner image transferred onto the recording material under the above-described image forming conditions was heat-fixed on the transfer material by the following heat-fixing device.
[0314]
As the heat fixing device 70, a heat roll type fixing device having no oil application function was used. At this time, both the upper roller 68 and the lower roller 69 had a fluororesin surface layer, and the roller diameter was 55 mm. The fixing temperature was set to 150 ° C., and the nip width was set to 7 mm.
[0315]
Using the image forming apparatus having the above configuration, a printout test of 1000 sheets was performed while replenishing toner, and image evaluation was performed. As a result, a high-quality image with high density and no image smearing was obtained.
[0316]
  Reference Example 14, Example 15, Reference Example 16
  A printout test was conducted in the same manner as in Example 13 except that toners (G) to (H) were used as toners. The results were generally good as shown in Table 6.
[0317]
Comparative Examples 5-8
A printout test was conducted in the same manner as in Example 13 except that comparative toners (c) to (f) were used as toners. As shown in Table 6, the toner was remarkably contaminated with the charging member, resulting in an image failure due to charging failure.
[0318]
[Table 6]

[0319]
Example 17
When toners (F) to (H) were used as toners and full-color image formation was attempted, good images were obtained.
[0320]
Comparative Example 9
Except for using the comparative toners (c) to (f) as the toner, an attempt was made to form a full-color image in the same manner as in Example 17. It was.
[0321]
Example 18
Image formation was performed using an image forming apparatus having a transfer belt shown in FIG.
[0322]
That is, the cleaning device 50 of the intermediate transfer belt 20 as the second cleaning unit of the image forming apparatus used in the thirteenth embodiment is removed, and the charging member 52 is contacted instead, and a bias having a polarity opposite to that of the photosensitive drum is applied. As a result, the transfer residual toner that is not transferred to the transfer material P but remains on the intermediate transfer belt is charged with a polarity opposite to that of the photosensitive drum, and the transfer residual toner is applied at and near the photosensitive drum. The intermediate transfer belt is cleaned by electrostatic transfer to the photosensitive drum, and the transfer residual toner transferred onto the photosensitive drum is recovered by operating the black developing unit 44 to clean the surface of the photosensitive drum. Set to do.
[0323]
When toners (F) to (H) were used as toners and full-color image formation was attempted, generally good images were obtained.
[0324]
Comparative Example 10
Except for using comparative toners (c) to (f) as the toner, full-color image formation was attempted in the same manner as in Example 18, but the toner adhesion to the charging roller and the intermediate transfer belt was remarkably stopped halfway. I had to do it.
[0325]
The description of the evaluation items described in the examples and comparative examples of the present invention and the evaluation criteria will be described.
[0326]
[Printout image evaluation]
<1> Image density
Ordinary paper for ordinary copying machines (75 g / m²The image density when a predetermined number of printouts were completed was evaluated. The image density was measured by using a “Macbeth reflection densitometer” (manufactured by Macbeth Co., Ltd.) to measure a relative density with respect to a printout image of a white background portion having a document density of 0.00.
[0327]
A: 1.40 or more
B: 1.35 or more and less than 1.40
C: 1.00 or more and less than 1.35
D: Less than 1.00
[0328]
<2> Image stain
The image contamination due to the charging failure appearing on the image in the period of the peripheral length of the charging roller was visually evaluated.
[0329]
A: Almost no occurrence
B: Slight image stains are seen
C: Some image dirt is seen
D: Significant image contamination is seen
[0330]
<3> Dot reproducibility
An image of an isolated dot pattern having a small diameter (50 μm) as shown in FIG. 8 which is easy to close due to the latent image electric field and difficult to reproduce was printed out, and the dot reproducibility was evaluated.
[0331]
A: Less than 2 defects / 100
B: 3-5 defects / 100 defects
C: 6-10 defects / 100 defects
D: 11 or more defects / 100
[0332]
<4> Image fog
The fog density (%) was calculated from the difference between the whiteness of the white portion of the printout image measured by “Reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper, and the image fogging was evaluated.
[0333]
A: Less than 1.5%
B: 1.5% or more and less than 2.5%
C: 2.5% or more and less than 4.0%
D: 4.0% or more
[0334]
<5> Image scattering
The “electric” character pattern shown in FIG.²) And cardboard (128 g / m²) Was visually evaluated for toner scattering (state of FIG. 9B) to the periphery of the character when printed.
[0335]
A: Almost no occurrence.
[0336]
B: Minor scattering is observed.
[0337]
C: Slight scattering is observed.
[0338]
D: Significant scattering is observed.
[0339]
<6> Image dropout
The “surprise” character pattern shown in FIG.²) Was visually evaluated for the voids in the characters when printed on (the state shown in FIG. 10B).
[0340]
A: There is almost no void.
[0341]
B: A slight void is observed.
[0342]
C: Some voids are observed.
[0343]
D: Significant void is seen.
[0344]
[Image forming device matching evaluation]
<1> Matching with developing sleeve
After completion of the printout test, the appearance of residual toner on the surface of the developing sleeve and the influence on the printout image were visually evaluated.
[0345]
A: No sticking occurred.
[0346]
B: Almost no sticking occurs.
[0347]
C: Although there is sticking, the influence on the image is small.
[0348]
D: There are many sticking and image unevenness occurs.
[0349]
<2> Matching with photosensitive drum
After completion of the printout test, the occurrence of scratches on the surface of the photosensitive drum and the sticking of the residual toner and the influence on the printout image were visually evaluated.
[0350]
A: Scratches and sticking did not occur.
[0351]
B: Scratches are slightly observed, but there is no influence on the image.
[0352]
C: Although there are sticking and scratches, the influence on the image is small.
[0353]
D: There are many stickings, and vertical streak-like image defects occur.
[0354]
<3> Matching with intermediate transfer member
After completion of the printout test, scratches on the surface of the intermediate transfer member and the adhesion state of the residual toner were visually evaluated.
[0355]
A: Scratches and sticking did not occur.
[0356]
B: Although the presence of residual toner is recognized on the surface, there is no influence on the image.
[0357]
C: Although there are sticking and scratches, the influence on the image is small.
[0358]
D: There are many fixations and image defects occur.
[0359]
<4> Matching with charging roller
After completion of the printout test, the toner adhesion state on the surface of the charging roller was visually evaluated.
[0360]
A: Almost no adhesion.
[0361]
B: Minor adhesion is observed.
[0362]
C: Some adhesion is observed.
[0363]
D: Significant adhesion is observed.
[0364]
【The invention's effect】
As described above, according to the present invention, the surface of the electrostatic latent image carrier is cleaned by the toner carrier collecting the toner remaining on the surface of the electrostatic latent image carrier during the development process. By precisely controlling the shape distribution of the toner used in the image forming apparatus having the simultaneous development cleaning method, high-quality image formability and stable matching with the image forming apparatus can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of an image forming apparatus using a two-component development process suitable for the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of an image forming apparatus used in a two-component development process suitable for the present invention.
FIG. 3 is a schematic explanatory view of an image forming apparatus using a one-component development process suitable for the present invention.
FIG. 4 is a schematic explanatory view of an image forming apparatus using an intermediate transfer belt provided with a blade cleaning device suitable for the present invention.
FIG. 5 is a schematic explanatory view of an image forming apparatus using an intermediate transfer belt provided with a charging roller cleaning device suitable for the present invention.
FIG. 6 is a schematic view showing an example of a cross section of toner particles encapsulating a wax component.
FIG. 7 is a schematic explanatory diagram of a DSC curve when the wax component according to the present invention is heated.
FIG. 8 is an explanatory diagram of an isolated dot pattern for checking toner development characteristics.
FIG. 9 is a schematic diagram illustrating a state where character images are scattered.
FIG. 10 is a schematic diagram illustrating a state in which a character image is missing.
[Explanation of symbols]
1 Developer carrier
2 Photoconductor (image carrier)
4 Transfer material
5 Charging brush roller
13 Non-magnetic blade
15 Developer
16 Two-component developer
24 Magnet
30 Toner
31 Charging roller
32 Developer container
33 Toner Regulation Blade
34 Toner carrier (elastic roller)
35 Toner application roller
36 photoconductor (image carrier)
37 Transfer roller
38 Transfer material
41 Development bias applying means
42 Transfer bias applying means
43 Fixing device
51 Photosensitive drum
52 Charging roller
53 Image exposure means
54 Transfer residual toner cleaning device
55 Transfer residual toner charging member
56 Bias power supply
62 Primary transfer roller
63 Secondary transfer roller
71 Yellow color developing device
72 Magenta color developing device
73 Cyan developing device
74 Black color developing device
76 Bias power supply
77 Intermediate transfer belt
78 Bias power supply
P transfer material

Claims (17)

A charging process in which a voltage is applied to the charging member from the outside to charge the electrostatic latent image carrier, a latent image forming process in which an electrostatic latent image is formed on the charged electrostatic latent image carrier, and a developer carrying The developer layer formed by the developer having the toner carried on the surface of the body is brought into contact with the surface of the electrostatic latent image carrier, whereby the electrostatic image is developed and the electrostatic image is carried. A developing process for forming on the body, a transfer process for transferring the toner image on the electrostatic latent image carrier to a transfer material, and a cleaning for collecting toner remaining on the surface of the electrostatic latent image carrier after the transfer process. In an image forming method having at least a step and a fixing step of heat-fixing a toner image on a transfer material,
The cleaning step is performed using a cleaning method in which the developer carrying member collects the toner remaining on the surface of the electrostatic latent image carrying member during the developing step, thereby cleaning the surface of the electrostatic latent image carrying member. And
The toner contains at least a binder resin, a colorant, and a wax component. The toner has a circle equivalent diameter-circularity scattergram based on the number of toners measured by a flow type particle image measuring device. equivalent number average diameter (D ₁₎ is 2 to 10 [mu] m, and the average circularity of the toner is at 0.970 to 0.990 state, and are less than 0.035 circularity standard deviation of 0.015 or more,
In the equivalent circle diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the toner has 15% by number or less of toner particles having a circularity of less than 0.950. Image forming method. In observation of the tomographic surface of toner particles using a transmission electron microscope (TEM) of the toner,
(1) The major axis R satisfying the relationship of 0.9 ≦ R / D ₄ ≦ 1.1 is set with respect to the weight-based equivalent weight average diameter D ₄ (μm) of the toner measured by the flow type particle image measuring apparatus. Select 20 tomographic planes of toner particles to be presented,
(2) The major axis r of the largest one of the phase separation structures resulting from the wax component present in the tomographic plane of the toner particles is measured for each,
(3) The calculated arithmetic average value of r / R is
0.05 ≦ r / R arithmetic mean value ≦ 0.95
So as to satisfy the image forming method according to claim 1, characterized in that the wax component is substantially dispersed in the spherical and / or islands of spindle in the binder resin. The arithmetic mean value of the r / R is
0.25 ≦ r / R arithmetic mean value ≦ 0.90
3. The image forming method according to claim 2 , wherein the wax component is dispersed in a substantially spherical and / or spindle-shaped island shape in the binder resin so as to satisfy the above. 0.1 to 50 parts by weight of 100 parts by weight of the binder resin of the toner is a polycarbonate resin, and the polycarbonate resin has a peak molecular weight of 1000 to 500,000 as determined by gel permeation chromatography (GPC). the image forming method according to any one of claims 1 to 3, characterized in that. The toner, image forming according to any one of claims 1 to 4, characterized in that it contains 0.1 to 10 parts by weight per 100 parts by weight of the binder resin of the azo type iron compound represented by the following general formula Method.

[Wherein, X ₁ and X ₂ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom, and X ₁ and X ₂ may be the same or different, and m and m ′ Represents an integer of 1 to 3, and R ₁ and R ₃ are a hydrogen atom, a C _{1 to} C ₁₈ alkyl group, a C _{2 to} C ₁₈ alkenyl group, a sulfonamide group, a mesyl group, a sulfonic acid group, and a carboxyester group. , hydroxy group, an alkoxy group of C ₁ -C _18, an acetylamino group, a benzoylamino group or a halogen atom, R ₁ and R ₃ may be different even in the same, n and n 'is 1 3 represents an integer, R ₂ and R ₄ represents a hydrogen atom or a nitro group, a ⁺ represents a cation, an ammonium ion, hydrogen ion, sodium ion, potassium ion or mixed ions thereof To. ] The toner has zirconium as a metal element and a zirconium complex or zirconium salt in which an aromatic diol, aromatic hydroxycarboxylic acid, or aromatic polycarboxylic acid is coordinated as a ligand, and / or a metal ion Zirconium ion as an acid ion, and an aromatic carboxylate ion, an aromatic hydroxycarboxylate ion, or an aromatic polycarboxylate ion as an acid ion, based on 100 parts by weight of the binder resin the image forming method according to any one of claims 1 to 5, characterized in that it contains 0.1 to 10 parts by weight. Developer, the image forming method according to any one of claims 1 to 6, characterized in that a two-component developer having the toner and carrier. Developer, the image forming method according to any one of claims 1 to 6, characterized in that a one-component developer having the toner. At least a charging step in which a voltage is applied to the charging member from the outside to charge the electrostatic latent image carrier, a latent image forming step in which an electrostatic latent image is formed on the charged electrostatic latent image carrier, and development A developer layer formed by a developer having toner carried on the surface of the agent carrying member is in contact with the surface of the electrostatic latent image carrying member, and the surface of the electrostatic latent image carrying member, the toner carrying member, The electrostatic image is developed by moving the surfaces of each other to form a toner image on the electrostatic latent image carrier, and the toner image on the electrostatic latent image carrier is transferred to the intermediate transfer member. A first transfer step, a second transfer step for transferring the toner image on the intermediate transfer member to the transfer material, and a toner remaining on the surface of the electrostatic latent image carrier after the first transfer step. At least a cleaning step and a fixing step for heat-fixing the toner image on the transfer material In the image forming method,
The first cleaning step uses a cleaning method in which the toner carrier collects the toner remaining on the surface of the electrostatic latent image carrier during the development step, thereby cleaning the surface of the electrostatic latent image carrier. Performed and
The toner contains at least a binder resin, a colorant, and a wax component. The toner has a circle equivalent diameter-circularity scattergram based on the number of toners measured by a flow type particle image measuring device. equivalent number average diameter (D ₁₎ is 2 to 10 [mu] m, and the average circularity of the toner is at 0.970 to 0.990 state, and are less than 0.035 circularity standard deviation of 0.015 or more,
In the equivalent circle diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring apparatus, the toner has 15% by number or less of toner particles having a circularity of less than 0.950. Image forming method. In observation of the tomographic surface of toner particles using a transmission electron microscope (TEM) of the toner,
(1) The major axis 11R satisfying the relationship of 0.9 ≦ R / D ₄ ≦ 1.1 with respect to the weight-based equivalent-circle weight average diameter D ₄ (μm) of the toner measured by the flow type particle image measuring device. Select 20 tomographic planes of toner particles to be presented,
(2) The major axis r of the largest one of the phase separation structures resulting from the wax component present in the tomographic plane of the toner particles is measured for each,
(3) The calculated arithmetic average value of r / R is
0.05 ≦ r / R arithmetic mean value ≦ 0.95
The image forming method according to claim 9 , wherein the wax component is dispersed in a substantially spherical and / or spindle-shaped island shape in the binder resin so as to satisfy the above condition. The arithmetic mean value of the r / R is
0.25 ≦ r / R arithmetic mean value ≦ 0.90
The image forming method according to claim 10 , wherein the wax component is dispersed in a substantially spherical and / or spindle-shaped island shape in the binder resin so as to satisfy the above condition. Out of 100 parts by weight of the binder resin of the toner, 0.1 to 50 parts by weight is a polycarbonate resin, and the polycarbonate resin has a peak molecular weight of 1000 to 500,000 as determined by gel permeation chromatography (GPC). the image forming method according to any one of claims 9 to 11, characterized in that. The toner, image forming according to any one of claims 9 to 12, characterized in that it contains 0.1 to 10 parts by weight per 100 parts by weight of the binder resin of the azo type iron compound represented by the following general formula Method.

[Wherein, X ₁ and X ₂ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom, and X ₁ and X ₂ may be the same or different, and m and m ′ represents an integer of 1 to 3, R1 and R ₃ are a hydrogen atom, an alkyl group of C ₁ -C _18, alkenyl group of C ₂ -C _18, a sulfonamide group, a mesyl group, a sulfonic acid group, carboxy ester group, hydroxy group, an alkoxy group of C ₁ -C _18, an acetylamino group, a benzoylamino group or a halogen atom, R ₁ and R ₃ may be different even in the same, n and n 'is 1-3 represents an integer, R ₂ and R ₄ represents a hydrogen atom or a nitro group, a ⁺ represents a cation, an ammonium ion, hydrogen ion, sodium ion, potassium ion or mixed ions thereof Have. ] The toner has zirconium as a metal element and a zirconium complex or zirconium salt in which an aromatic diol, aromatic hydroxycarboxylic acid, or aromatic polycarboxylic acid is coordinated as a ligand, and / or a metal ion Zirconium ion as an acid ion, and an aromatic carboxylate ion, an aromatic hydroxycarboxylate ion, or an aromatic polycarboxylate ion as an acid ion, based on 100 parts by weight of the binder resin the image forming method according to any one of claims 9 to 12, characterized in that it contains 0.1 to 10 parts by weight. The surface of the intermediate transfer member is cleaned by applying a bias having a polarity opposite to that of the electrostatic latent image carrier by the charging member and transferring the toner remaining on the surface of the intermediate transfer member to the electrostatic latent image carrier. the image forming method according to any one of claims 9 to 14, characterized in that a cleaning step of performing. Developer, the image forming method according to any one of claims 9 to 15, characterized in that a two-component developer having the toner and carrier. 16. The image forming method according to claim 9 , wherein the developer is a one-component developer having the toner.

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