JP3754802B2 - Toner for developing electrostatic image and image forming method - Google Patents

Description

【００２４】
また、本発明は、静電潜像担持体を帯電する工程；
帯電された該静電潜像担持体に静電潜像を形成する工程；
該静電潜像担持体上にトナー像を形成するために、該静電潜像をトナー担持体上に担持されているトナーによって現像する工程；及び
電圧が印加されている転写部材を転写材に接触させて、該静電潜像担持体上のトナー像を転写材に転写する工程；
を有する画像形成方法において、
該トナーは結着樹脂及び着色剤を少なくとも含有するトナー粒子、及び無機微粉体を少なくとも有しており、
該トナーは、示差熱分析における吸熱ピークを６０℃乃至１２０℃の温度領域に１つ以上有しており、
該トナーは、粒径３μｍ以上の粒子において、上記式より求められる円形度ａが０．９０以上の粒子を９０個数％以上有し、かつ、円形度ａが０．９８以上の粒子を３０個数％未満有しており、
該トナーは、粒径３μｍ以上の粒子において、上記式より求められる円形度分布の標準偏差ＳＤが０．０４５以下であり、
該トナーは、重量平均粒径が８．０μｍ以下であり、
該トナーは、溶融・混練工程及び粉砕工程を少なくとも有するトナーの製造工程において、少なくとも機械的衝撃力を加える球形化処理が施されていることを特徴とする画像形成方法に関する。
【００２５】
さらに、本発明は、静電潜像担持体を帯電する工程；
帯電された該静電潜像担持体に静電潜像を形成する工程；
該静電潜像担持体上にトナー像を形成するために、該静電潜像をトナー担持体上に担持されているトナーによって現像する工程；
該静電潜像担持体上のトナー像を中間転写体に１次転写する工程；及び
電圧が印加されている転写部材を記録材に接触させて、該中間転写体上のトナー像を記録材に２次転写する工程；
を有する画像形成方法において、
該トナーは結着樹脂及び着色剤を少なくとも含有するトナー粒子、及び無機微粉体を少なくとも有しており、
該トナーは、示差熱分析における吸熱ピークを６０℃乃至１２０℃の温度領域に１つ以上有しており、該トナーは粒径３μｍ以上の粒子において、上記式より求められる円形度ａが０．９０以上の粒子を９０個数％以上有し、かつ、円形度ａが０．９８以上の粒子を３０個数％未満有しており、
該トナーは、粒径３μｍ以上の粒子において、上記式より求められる円形度分布の標準偏差ＳＤが０．０４５以下であり、
該トナーは、重量平均粒径が８．０μｍ以下であり、
該トナーは、溶融・混練工程及び粉砕工程を少なくとも有するトナーの製造工程において、少なくとも機械的衝撃力を加える球形化処理が施されていることを特徴とする画像形成方法に関する。
【００２６】
【発明の実施の形態】
本発明における円形度とは、粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明では東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて測定を行い、下記式（１）より得られた値を円形度と定義する。
【００２７】
【数８】

【００２８】
具体的な測定方法としては、容器中の予め不純固形物を除去した水１００〜１５０ｍｌ中に分散剤として界面活性剤、好ましくはアルキルベンゼンスフォン酸塩を０．１〜０．５ｍｌ加え、更に測定試料を０．１〜０．５ｇ程度加える。試料を分散した懸濁液は超音波分散器で約１〜３分間分散処理を行ない、分散液濃度を３０００〜１万個／μｌとして前記装置によりトナーの形状、粒度を測定する。
【００２９】
本発明における円形度はトナー粒子の凹凸の度合いの指標であり、トナーが完全な球形の場合１．００を示し、表面形状が複雑になるほど円形度は小さな値となる。
【００３０】
さらに、本発明において、円形度分布の標準偏差ＳＤは各粒子の円形度と平均円形度より、下記式（２）により求められた値を用いる。
【００３１】
【数９】

【００３２】
本発明における円形度分布のＳＤは、分布の広さの指標であり、数値が小さい程ばらつきのないシャープな分布であることを示す。
【００３３】
本発明者らは、トナーの円形度の分布と転写性の関係について調べたところ、非常に深い関わりがあることを見出し、本発明に至ったものである。
【００３４】
本発明のトナーは、粒径３μｍ以上の粒子において、円形度ａが０．９０以上の粒子を、９０個数％以上（９０〜１００個数％）、より好ましくは９３個数％以上（９３〜１００個数％）有しており、かつ円形度ａが０．９８以上の粒子を３０個数％未満（０〜３０個数％未満）有していることが良く、さらに好ましくはトナーの粒径３μｍ以上の粒子における円形度分布の標準偏差ＳＤが０．０４５以下（０＜ＳＤ≦０．０４５）、より好ましくは０．０４０以下（０＜ＳＤ≦０．０４０）であることにより、弊害無く上記課題を解決できる。
【００３５】
トナーの円形度ａが０．９０以上の粒子の含有量が、９０個数％未満であると、静電潜像担持体から転写材への転写時におけるトナー像の転写効率の低下、及び文字やラインの転写中抜けを招き好ましくなく、さらに、トナーの円形度ａが０．９８以上の粒子の含有量が３０個数％を超えるとクリーニング不良が発生しやすくなる。
【００３６】
さらに、トナーの粒径３μｍ以上の粒子における円形度分布の標準偏差ＳＤが０．０４５以下であると、さらに優れた転写性が得られる。
【００３７】
その理由としては、現像工程においてトナー担持体上にトナーの薄層を形成する際に、トナー層厚規制部材の規制力を通常よりも強くしても十分なトナーコート量を保つことができるため、トナー担持体に対するダメージを与えることなくトナー担持体上のトナーの帯電量を通常よりも高くすることが可能となるからである。
【００３８】
このため、従来では困難であった静電潜像の電位コントラストが４００Ｖ以下、さらには３５０Ｖ以下の低電位潜像に対する現像能力が大幅に改善される。特にデジタル方式の微小スポット潜像を現像する場合に有効である。
【００３９】
さらに、同時に磁性トナーであっても非磁性トナーと同様の幅広い転写電流条件（特に高い転写電流条件）において「再転写」を起こさず高い画像濃度を得ることが容易となる。
【００４０】
一般に磁性トナーは、非磁性トナーよりも低抵抗であり、転写電流条件が磁性トナーは低めに、非磁性トナーは高めに設定される。
【００４１】
近年、フルカラー画像を得る方法として、単色での耐久安定性に優れ、長寿命化が容易な黒トナーを磁性トナーとし、他のカラートナーを非磁性トナーとする組み合せが注目されている。
【００４２】
本発明を、磁性トナーと非磁性トナーを組合わせたフルカラー画像形成方法における磁性トナーあるいは、磁性トナーと非磁性トナー双方に用いることにより転写電流条件を磁性トナーであっても非磁性トナー並の設定を取ることが可能となる。
【００４３】
従って、後述する中間転写体を用いた画像形成方法において、磁性トナーに本発明のトナーの構成を用い、この磁性トナーを非磁性シアントナー、非磁性イエロートナー及び非磁性マゼンタトナーからなるグループから選択される１種以上の非磁性カラートナーと共に用いて、該中間転写体上に順次静電潜像担持体から１次転写し、中間転写体上に１次転写された磁性トナーと非磁性カラートナーとを組み合わせたカラートナー像を記録材に一括転写する際に、非磁性カラートナーに適した高めの転写電流条件で転写を行なっても、非磁性カラートナーと同様に磁性トナーも良好に転写されるため、転写不良が生じ難い。
【００４４】
本発明のトナーは、トナーの示差熱分析における吸熱ピークを１２０℃以下の温度領域、好ましくは１１０℃以下の温度領域に１つ以上有している。
【００４５】
トナーの示差熱分析における吸熱ピークが１２０℃以下の温度領域に無い場合は、本発明の効果が十分に得られない。
【００４６】
すなわち、トナーの示差熱分析における吸熱ピークを１２０℃以下の温度領域に有するトナーは、その製造における溶融混練工程においてバインダー樹脂中の磁性体及び電荷制御剤の分散の状態が吸熱ピークが、吸熱ピークを１２０℃以下の温度領域に有していないトナーとは異なり「ある特異な状態」になるものと推測される。そのある特異な状態が本発明トナーの表面性に影響を与え、転写性向上の効果を発揮しやすい状態にしているものと推測している。
【００４７】
すなわち、トナーは、トナーの示差熱分析における吸熱ピークを１２０℃以下の温度領域に有することにより、上記のトナーの特定の円形度分布を容易に達成することが可能であり、特に上記のトナーの特定の円形度分布を達成するためにトナーに機械的衝撃力を加える処理を必要とする際には、装置内の温度上昇を適度に保つ効果があり、装置へのトナー融着を発生することなく適度なトナーの表面性を得ることができる。
【００４８】
本発明において、トナーは、トナーの示差熱分析における吸熱ピークを１２０℃以下の温度領域に少なくとも１つ有していれば効果はあり、さらに１２０℃を超える温度領域に他の吸熱ピークを有していても構わない。本発明においては、トナーは、トナーの示差熱分析における吸熱ピークを６０℃以下の温度領域、好ましくは７０℃以下の温度領域に有していないことがより好ましい。トナーがトナーの示差熱分析における吸熱ピークを６０℃以下の温度領域に有する場合には画像濃度が低くなる傾向があり、さらに、保存性も不安定になる傾向にある。
【００４９】
トナーがトナーの示差熱分析における吸熱ピークを１２０℃以下の温度領域に有する形態にするための手段としては、トナー中に、示差熱分析における吸熱ピークを１２０℃以下の温度領域に有する化合物を内添させる方法が好ましい。
【００５０】
示差熱分析における吸熱ピークを１２０℃以下の温度領域に１つ以上有する物質としては、樹脂あるいはワックスを挙げることができる。
【００５１】
樹脂としては、結晶性を有するポリエステル樹脂及びシリコーン樹脂を挙げることができる。
【００５２】
ワックスとしては、パラフィンワックス、マイクロクリスタリンワックス及びペトロラクタムの如き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；カルナバワックス及びキャンデリラワックスの如き天然ワックス及びそれらの誘導体；高級脂肪族アルコールの如きアルコール；ステアリン酸及びパルミチン酸の如き脂肪酸或いはその誘導体；酸アミド及びその誘導体，エステル及びその誘導体，ケトン及びその誘導体，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。
【００５３】
上記の誘導体は、酸化物及びビニルモノマーとのブロック共重合物又はグラフト変性物を含む。
【００５４】
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、石油系ワックス又は高級アルコールがトナー母体の帯電を安定させる効果があり、再転写防止効果がさらに高まるため、本発明のトナーにおいては特に好ましい。
【００５５】
上記の特定の化合物を用いた場合、「再転写」防止の効果がさらに高くなる。
【００５６】
これらの化合物は比較的それ自身の極性が低く、トナーの帯電を安定させるものと考えられる。
【００５７】
示差熱分析における吸熱ピークを１２０℃以下の温度領域に有する化合物が、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、石油系ワックス及び高級アルコールからなるグループから選択されるワックスであり、かつこのワックスのＧＰＣ測定での重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）の比（Ｍｗ／Ｍｎ）が１．０〜２．０、より好ましくは１．０〜１．５である場合、「再転写」防止の効果がさらに高くなる。
【００５８】
重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比（Ｍｗ／Ｍｎ）が１．０〜２．０である分子量分布がかなりシャープな上記ワックスをトナー中に含有させることにより、トナーの製造における溶融混練工程においてバインダー樹脂中の磁性体及び電荷制御剤の分散の状態が、より好ましくなるためと考えている。
【００５９】
本発明に係るトナーの吸熱ピークの測定には、例えばパーキンエルマー社製のＤＳＣ−７のような、高精度の内熱式入力補償型の示差走査熱量計で測定されるＤＳＣ曲線を用いる。
【００６０】
測定方法は、ＡＳＴＭ Ｄ３４１８−８２に準じて行う。本発明に用いられるＤＳＣ曲線は、１回昇温させ前履歴をとった後、温度速度１０℃／ｍｉｎ、温度０〜２００℃の範囲で降温、昇温させたときに測定されるＤＳＣ曲線を用いる。
【００６１】
吸熱ピーク温度とは、ＤＳＣ曲線に於て、プラスの方向のピーク温度のことであり、即ち、ピーク曲線の微分値が正から負にかわる際の０になる点を言う。
【００６２】
本発明において、トナーは、結着樹脂のＧＰＣ測定による分子量分布において、メインピークが分子量１５０００を超える分子量領域にあることがトナーの円形度分布の標準偏差を制御するうえで好ましく、より好ましくは分子量１００００以下の成分の割合が好ましくは２５％以下、より好ましくは２０％以下であることが良い。
【００６３】
トナーの結着樹脂のＧＰＣ測定による分子量分布において、メインピークが分子量１５０００以下の分子量領域に存在する場合、あるいは、分子量１００００以下の成分の割合が２５％を超える場合には、機械的衝撃に対してもろくなりやすく、必要以上に粉砕されやすいため、トナーの円形度分布が広くなり本発明で規定している範囲内に制御することが困難になる傾向であり、さらに静電潜像担持体の如きトナーの接触する部材のトナーによる汚染・融着が生じやすい傾向があり帯電不良及び画像欠陥の原因となりやすい。
【００６４】
特にトナーを粉砕後に機械的衝撃力を加えて球形化処理を行う場合では、メインピークが分子量１５０００を超える分子量領域に存在する場合には、粉砕工程が完了した時点でトナーの円形度をある程度揃えておくことが可能となり、次いで行われる球形化処理によって円形度分布を本発明で規定している範囲にすることが容易となり転写性の点で好ましく、さらに像担持体等のトナーが接触する部材のトナーによる汚染融着を防止でき、耐久性向上の点で好ましい。
【００６５】
分子量１５０００以下の分子量領域にピーク又はショルダーを有していないことが、機械的衝撃力を加える球形化処理工程における現像に悪影響を及ぼすトナーの超微粉発生を抑制し得ることでより好ましい。
【００６６】
すなわち、本発明のトナーは、図５に示す通り、トナー原料を溶融・混練工程で溶融・混練し、混練物を粗粉砕工程で粗粉砕し、粗粉砕物を微粉砕工程で微粉砕し、微粉砕物を第１分級工程で所定の規定粒径内の粒子と規定粒径より大きい粒子とを分け、このうち規定粒径内の粒子は、第２分級工程でさらに所定の粒径の範囲の粒子のみを分級し、その所定の粒径範囲内の分級品を球形化処理工程で球形化処理を行ったトナー粒子を得、一方、第１分級工程で規定粒径より大きい粒子は、再度微粉砕工程に導入され、以降の工程が行われるような製造方法によって製造される。
【００６７】
このような製造方法に、前述の如きトナーの結着樹脂のＧＰＣ測定による分子量分布において、メインピークが分子量１５０００を超える分子量領域に存在するような硬い結着樹脂を含有するトナーの場合には、微粉砕工程で粉砕され難いことから、第１分級工程で分級後に再度微粉砕工程に戻る粒子が多く、通常この微粉砕工程に複数回繰り返し導入される。
【００６８】
この微粉砕工程を複数回繰り返すことにより、球形化処理工程に導入される前の分級品の球形化が適度に行なわれ、かつ、円形度が適度に揃った状態になることから、後の球形化処理工程を経て得られるトナーの円形度分布を本発明で規定する範囲内に好ましく調整することができる。特に粒径の小さいトナーの場合には、微粉砕工程に導入される回数が増えることから、より円形度を揃えることができる。
【００６９】
本発明において、トナーの結着樹脂の分子量分布は、ＧＰＣ（ゲルパーミエーションクロマトグラフィー）により測定される。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ＴＨＦ（テトラヒドロフラン）溶剤で２０時間抽出を行ったサンプルを用い、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。
【００７０】
本発明に使用される結着樹脂の種類としては、例えば、ポリスチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如きスチレン及びその置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体の如きスチレン系共重合体；ポリ塩化ビニル、フェノール樹脂、天然変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニール、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロンインデン樹脂及び石油系樹脂が使用できる。架橋されたスチレン系樹脂も好ましい結着樹脂である。
【００７１】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、アクリロニトリル、メタクリロニトリル、アクリルアミドのような二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチルのような二重結合を有するジカルボン酸及びその置換体；例えば、塩化ビニル、酢酸ビニル、安息香酸ビニルのようなビニルエステル類；例えば、エチレン、プロピレン、ブチレンのようなエチレン系オレフィン類；例えば、ビニルメチルケトン、ビニルヘキシルケトンのようなビニルケトン類；例えば、ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルのようなビニルエーテル類；が挙げられる。これらのビニル単量体は、単独もしくは組み合わせて用いられる。
【００７２】
ここで架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられ、例えば、ジビニルベンゼン、ジビニルナフタレンのような芳香族ジビニル化合物；例えば、エチレングリコールジアクリレート、エチレングリコールジメタクリレート及び１，３−ブタンジオールジメタクリレートのような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド及びジビニルスルホンのジビニル化合物；及び３個以上のビニル基を有する化合物；が単独もしくは混合物として使用できる。
【００７３】
圧力定着用に供されるトナー用の結着樹脂としては、低分子量ポリエチレン，低分子量ポリプロピレン，エチレン−酢酸ビニル共重合体，エチレン−アクリル酸エステル共重合体，高級脂肪酸，ポリアミド樹脂及びポリエステル樹脂が挙げられる。これらは単独又は混合して用いることが好ましい。
【００７４】
本発明のトナーには荷電制御剤をトナー粒子に配合（内添）、又はトナー粒子と混合（外添）して用いることが好ましい。荷電制御剤によって、現像システムに応じた最適の荷電量コントロールが可能となり、特に本発明のトナーにおいては、粒度分布と荷電量とのバランスを更に安定したものとすることが可能である。トナーを負荷電性に制御するための負荷電制御剤としては、下記物質がある。
【００７５】
例えば有機金属錯体、キレート化合物が有効であり、モノアゾ金属錯体、アセチルアセトン金属錯体、芳香族ハイドロキシカルボン酸金属錯体、芳香族ジカルボン酸金属錯体がある。他には、芳香族ハイドロキシカルボン酸、芳香族モノカルボン酸及び芳香族ポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノールの如きフェノール誘導体類がある。
【００７６】
トナーを正荷電性に制御するための正荷電制御剤として下記物質がある。
【００７７】
例えば、ニグロシン及び脂肪酸金属塩等による変性物；トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートの如き四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩の如きオニウム塩及びこれらのレーキ顔料；トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、燐タングステン酸、燐モリブデン酸、燐タングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物等）；高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドの如きジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートの如きジオルガノスズボレート類；がある。
【００７８】
これらの荷電制御剤は、単独あるいは２種類以上組み合わせて用いることができる。
【００７９】
上述した荷電制御剤は微粒子状として用いることが好ましく、この場合これらの荷電制御剤の個数平均粒径は４μｍ以下さらには３μｍ以下が特に好ましい。これらの荷電制御剤をトナーに内添する場合は、結着樹脂１００重量部に対して０．１〜２０重量部、特に０．２〜１０重量部トナーに含有されることが好ましい。
【００８０】
本発明に用いられる着色剤は、黒色着色剤としてカーボンブラック，磁性体，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の如き有彩色着色剤によって黒色に調色されるように組み合わせたものが利用される。
【００８１】
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、９７、１０９、１１０、１１１、１２０、１２７、１２８、１２９、１４７、１６８、１７４、１７６、１８０、１８１、１９１が好適に用いられる。
【００８２】
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。
【００８３】
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。
【００８４】
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。本発明において、着色剤は、色相角，彩度，明度，耐候性，ＯＨＰ透明性，トナー中への分散性を考慮して選択される。これらの有彩色着色剤は、結着樹脂１００重量部に対し１〜２０重量部トナー中に含有される。
【００８５】
磁性体としては、鉄，コバルト，ニッケル，銅，マグネシウム，マンガン，アルミニウム又は珪素の元素を含む金属酸化物などがある。中でも四三酸化鉄，γ−酸化鉄の如き酸化鉄を主成分とするものが好ましい。トナー帯電性コントロールの観点から硅素元素またはアルミニウム元素の如き他の元素を含有していてもよい。これら磁性粒子は、窒素吸着法によるＢＥＴ比表面積が好ましく２〜３０ｍ²／ｇ、特に３〜２８ｍ²／ｇ、更にモース硬度が５〜７の磁性粉が好ましい。
【００８６】
磁性体の形状としては、８面体，６面体，球体，針状，鱗片状などがあるが、８面体，６面体，球体及び不定型の如き異方性の少ない形状のものが画像濃度を高める上で好ましい。磁性体の平均粒径としては、好ましくは０．０５〜１．０μｍ、より好ましくは０．１〜０．６μｍ、さらに好ましくは、０．１〜０．４μｍであることが良い。
【００８７】
磁性体の含有量は結着樹脂１００重量部に対し、好ましくは３０〜２００重量部、より好ましくは４０〜２００重量部、さらに好ましくは５０〜１５０重量部であることが良い。３０重量部未満ではトナー搬送に磁気力を用いる現像器においては、搬送性が不十分で現像剤担持体上の現像剤層にむらが生じ画像むらとなる傾向であり、さらに現像剤トリボの上昇に起因する画像濃度の低下が生じ易い傾向であった。含有量が２００重量部を超えると定着性に問題が生ずる傾向であった。
【００８８】
本発明のトナーにおいて、トナー粒子と共に含有される無機微粉体としては公知のものを用いることができるが、帯電安定性，現像性，流動性及び保存性向上のため、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。さらには、シリカであることがより好ましい。例えば、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シリカ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-の如き製造残滓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，塩化チタンの如き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。
【００８９】
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る。
【００９０】
この無機微粉体のトナーにおける含有量は、トナー１００重量部に対して好ましくは０．１〜８重量部、より好ましくは０．５〜５重量部、さらに好ましくは１．０を超えて３．０重量部まであることが良い。
【００９１】
本発明に用いられる無機微粉体は、必要に応じ、疎水化及び帯電性制御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，有機チタン化合物の如き処理剤を単独で、あるいは、併用して処理されているが好ましい。
【００９２】
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。
【００９３】
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。
【００９４】
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の如き研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末の如き流動性付与剤；ケーキング防止剤；例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末の如き導電性付与剤；逆極性の有機微粒子及び逆極性の無機微粒子の如き現像性向上剤用いることもできる。
【００９５】
本発明に係るトナーを作製するには、例えば、結着樹脂、ワックス、金属塩ないしは金属錯体、着色剤としての顔料、染料、又は磁性体、必要に応じて荷電制御剤、その他の添加剤をヘンシェルミキサー、ボールミルの如き混合器により十分混合してから加熱ロール、ニーダー、エクストルーダーの如き熱混練機を用いて溶融混練して樹脂類をお互いに相溶せしめた中に金属化合物、顔料、染料、磁性体を分散又は溶解せしめ、冷却固化、粉砕後、必要に応じて分級及び表面処理を行なってトナー粒子を得、必要に応じ無機微粉体等を添加混合して製造する方法が好ましく用いられる。
【００９６】
本発明トナーの特定の円形度分布を達成するためには、示差熱分析における吸熱ピークを１２０℃以下にひとつ以上有するトナーでは機械衝撃式粉砕装置及びジェット式粉砕装置の如き一般的な粉砕装置を用いた方法により粉砕（必要に応じて分級）するだけでも良いが、さらに補助的に機械的衝撃を加える処理をすることが、よりシャープな円形度分布が得られ、転写条件のラチチュードが広くなる点で好ましい。
【００９７】
微粉砕（必要に応じて分級）されたトナー粒子を熱水中に分散させる湯浴法、熱気流中を通過させる方法を用いてもよいが、トナーの帯電量が低くなり転写特性及びその他の画像特性、さらに生産性の面でも機械的衝撃力による処理を加える方法が最も好ましい。
【００９８】
機械的衝撃力を加える処理としては、例えば、川崎重工社製のクリプトロンシステムやターボ工業社製のターボミルの如き機械衝撃式粉砕機を用いる方法；或いは、ホソカワミクロン社製のメカノフュージョンシステムや奈良機械製作所製のハイブリダイゼーションシステム等の装置のように、高速回転する羽根によりトナーをケーシングの内側に遠心力により押し付け、圧縮力及び摩擦力によりトナーに機械的衝撃力を加える方法；が挙げられる。
【００９９】
本発明において、トナーの円形度をコントロールするための衝撃式表面処理装置を用いた処理システムについて、図８及び図９を用いて説明する。
【０１００】
５１は本体ケーシング、５８はステーター、７７はステータージャケット、６３はリサイクルパイプ、５９は排出バルブ、１９は排出シュート、６４は原料ホッパーである。
【０１０１】
衝撃式表面処理装置では図８及び図９に示すように、駆動手段によって回転軸６１を駆動し、表面処理すべき物質の性質により粒子が解砕しない程度の周速で回転ローター６２を回転させ、該回転ローター６２の回転に伴って発生した急激な気流により、衝撃室６８に開口するリサイクルパイプ６３を巡って回転ローター６２の中心部に戻る循環流れを起こす。
【０１０２】
該装置において、原料ホッパー６４から供給された被処理粉体は、衝撃室６８内で主として高速で回転している回転ローター６２に配置された複数のローターブレード５５によって瞬間的な打撃作用を受け、さらに周辺のステーター５８に衝突して衝撃作用を受けた後、被処理粒子の角取り又は球形化が行なわれる。この状態は粒子の飛行と衝突に伴って進んで行く。すなわち、ローターブレード５５の回転により発生する気流の流れに伴って、該粒子は、６３のリサイクルパイプを複数回通過することにより処理される。さらにローターブレード５５及びステーター５８から該粒子が繰り返し打撃作用を受けることにより、被処理粉体は、粒子の形状が球形化されていく。
【０１０３】
球形化が完了した処理粉体は、排出弁制御装置２８により排出バルブ５９を開くことにより、１９の排出シュートを通過し吸引ブロア２４と連通しているバグフィルター２２により捕集される。
【０１０４】
球形化が完了した処理粉体は、排出弁制御装置２８により排出バルブ５９を開くことにより、１９の排出シュートを通過し吸引ブロア２４と連通しているバグフィルター２２により捕集される。
【０１０５】
ローターブレード５５の周速は６０ｍ／秒から１５０ｍ／秒の範囲になるように回転盤を回転させることが好ましい。
【０１０６】
また、この表面処理装置は、ジャケット７７に冷却水を通すことにより、冷却が可能であり、処理温度のコントロールがある程度可能となる。
【０１０７】
機械的衝撃力を加える処理は、トナーの微粉砕工程の後、あるいは、さらに分級工程を経た後に行う場合、「再転写」防止の効果がさらに高まり特に好ましい。
【０１０８】
分級及び表面処理の順序はどちらが先でも良いが、分級を行なった後、表面処理を行なうことが、トナー微粉による装置内の融着を防止でき好ましい。分級工程においては生産効率上、多分割分級機を用いることが好ましい。
【０１０９】
機械的衝撃法において処理温度をトナー粒子のガラス転移点Ｔｇ付近の温度（Ｔｇ±１０℃）に設定して熱機械的衝撃を付与することが、凝集防止、生産性の観点から好ましい。さらに好ましくは、トナーのガラス転移点Ｔｇ±５℃の範囲の温度で行うことが現像能力と転写効率を向上させるのに特に有効である。
【０１１０】
トナーの重量平均粒径は１０．０μｍ以下、好ましくは３．０〜８．０μｍの範囲内であることが好ましい。トナーの重量平均粒径が１０．０μｍ以下であるとき、「再転写」の防止効果がさらに高まる。その理由としては、トナーの重量平均粒径は１０．０μｍ以下であるとき、転写前の静電潜像担持体あるいは中間転写体上のトナーの帯電量がさらに高くなるためと考えられる。
【０１１１】
トナーの重量平均粒径が小さすぎる場合には、トナー担持体の汚染等により、画像濃度が低下することがある。
【０１１２】
本発明トナーの重量平均粒径はコールターカウンターＴＡ−ＩＩ型あるいはコールターマルチサイザー（コールター社製）を用いる。電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。例えばＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルフォン酸塩）を０．１〜５ｍｌ加え、さらに測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行ない前記装置によりアパーチャーとして１００μｍアパーチャーを用いて、２μｍ以上のトナーの体積，個数を測定して体積分布と個数分布とを算出した。それから、本発明に係わる体積分布から求めた体積基準の重量平均粒径（Ｄ４）を求めた。
【０１１３】
本発明は、静電潜像担持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の如き無機静電潜像担持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像担持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▼撥水性及び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、ことが挙げられる。▲１▼の例としては、樹脂の構造中にフッ素含有基、シリコン含有基を導入することにより達成する。▲２▼としては、界面活性剤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、フッ化カーボンの如き含フッ素化合物粉体が挙げられる。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▼の含フッ素樹脂の如き離型性粉体の最表面層への分散が特に好適である。
【０１１４】
これらの手段によって静電潜像担持体表面の水に対する接触角を８５度以上（好ましくは９０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。
【０１１５】
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像担持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像担持体であれば、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。
【０１１６】
該粉体の表面層への添加量は、表面層総質量に対して、１〜６０重量％、さらには、２〜５０重量％が好ましい。１重量％より少ないとトナー及びトナー担持体の耐久性改善の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、像担持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。
【０１１７】
本発明は、帯電手段が帯電部材を像担持体に当接させる直接帯電法の場合に特に効果的である。帯電手段が像担持体に接することのないコロナ放電等に比べて、像担持体表面に対する負荷が大きいので像担持体寿命という点で改善効果が顕著であり、好ましい適用形態の一つである。
【０１１８】
本発明に用いられる静電潜像担持体の好ましい態様のひとつを以下に説明する。
【０１１９】
導電性基体としては、アルミニウム，ステンレスの如き金属；アルミニウム合金，酸化インジウム−酸化錫合金による被膜層を有するプラスチック；導電性粒子を含浸させた紙又はプラスチック；又は導電性ポリマーを有するプラスチック；の円筒状シリンダー及びフィルムが用いられる。
【０１２０】
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，基体上の欠陥の被覆，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，ポリウレタン又は酸化アルミニウム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。
【０１２１】
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、セレン及び非晶質シリコンの如き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あるいは蒸着により形成される。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，エポキシ樹脂及び酢酸ビニル樹脂が挙げられる。電荷発生層中に含有される結着剤の量は、電荷発生物質の重量を として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。
【０１２２】
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，ピレン又はフェナントレン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，オキサジアゾール又はピラゾリン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；硫化カドニウムが挙げられる。
【０１２３】
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，ポリアミド樹脂の如き熱可塑性樹脂及びポリ−Ｎ−ビニルカルバゾール，ポリビニルアントラセンの如き有機光導電性ポリマーが挙げられる。
【０１２４】
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が単独あるいは２種以上組み合わされて用いられる。
【０１２５】
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及び酸化ジルコニウムの超微粒子があげられる。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。
【０１２６】
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。
【０１２７】
保護層中での含有量は、保護層総質量に対して２〜９０質量％が好ましく、５〜８０質量％がより好ましい。
【０１２８】
保護層の膜厚は、０．１〜１０μｍが好ましく、１〜７μｍがより好ましい。
【０１２９】
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コーティングすることによって行うことができる。
【０１３０】
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。
【０１３１】
接触転写工程とは、静電荷像担持体又は中間転写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。
【０１３２】
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構成され、導電性弾性層はカーボンの如き導電材を分散させたウレタンやＥＰＤＭの如き、体積抵抗１０⁶〜１０¹⁰Ωｃｍ程度の弾性体で作られている。
【０１３３】
本発明は、静電潜像担持体（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。
【０１３４】
本発明に係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が挙げられるが、これらに限定されること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も使用することができる。
【０１３５】
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。
【０１３６】
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。
【０１３７】
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、直流電圧に交流電圧を重畳したものを用いたときには、交流電圧＝０．５〜５ｋＶｐｐ，交流周波数＝５０〜５ｋＨｚ，直流電圧＝±０．２〜±５ｋＶである。
【０１３８】
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。
【０１３９】
本発明は、現像工程においてトナー担持体上にトナーの薄層を形成する手段として、トナー層厚を規制する部材をトナー担持体上に弾性力で当接して用いることにより、現像されるトナーの帯電量が高くなり特に転写性の点で好ましい。弾性力で当接するトナー層厚規制部材は、例えばゴム状弾性あるいは金属の板バネの弾性を利用したものを用いることができる。
【０１４０】
接触帯電手段としての帯電ローラー及び帯電ブレードの材質としては、導電性ゴムが好ましく、その表面に離型性被膜を設けてもよい。離型性被膜としては、ナイロン系樹脂，ＰＶＤＦ（ポリフッ化ビニリデン），ＰＶＤＣ（ポリ塩化ビニリデン）及びフッ素アクリル樹脂が適用可能である。
【０１４１】
次に、本発明の画像形成方法を図に沿って具体的に説明する。
【０１４２】
図１は、静電潜像担持体上のトナー像を転写材に直接転写するタイプの画像形成装置を示す。
【０１４３】
図１において、１００は静電潜像担持体としての感光ドラムであり、その周囲に一次帯電ローラー１１７、現像器１４０、転写帯電ローラー１１４、クリーナ１１６、レジスタローラー１２４が設けられている。そして感光ドラム１００は一次帯電ローラー１１７によって−７００Ｖに帯電される（印加電圧は交流電圧−２．０ｋＶｐｐ、直流電圧−７００Ｖｄｃ）。そして、レーザー発生装置１２１によりレーザー光１２３を感光ドラム１００に照射することによって露光され、静電潜像が形成される。感光ドラム１００上の静電潜像は現像器１４０によって一成分磁性トナーで現像され、転写材を介して感光ドラムに当接された転写ローラー１１４により転写材上へ転写される。トナー画像をのせた転写材は搬送ベルト１２５により定着器１２６へ運ばれ転写材上に定着される。静電潜像担持体上に一部残されたトナーはクリーニング手段１１６によりクリーニングされる。
【０１４４】
現像器１４０は図２に示すように感光ドラム１００に近接してアルミニウム及びステンレスの如き非磁性金属で作られた円筒状のトナー担持体１０２（以下現像スリーブと称す）が配設され、感光ドラム１００と現像スリーブ１０２との間隙は図示されないスリーブ／ドラム間隙保持部材により約３００μｍに維持されている。現像器内には攪拌棒１４１が配設されている。現像スリーブ内にはマグネットローラー１０４が現像スリーブ１０２と同心的に固定、配設されている。但し、現像スリーブ１０２は回転可能である。マグネットローラー１０４には図示の如く複数の磁極が具備されており、Ｓ₁は現像、Ｎ₁はトナーコート量規制、Ｓ₂はトナーの取り込み／搬送、Ｎ₂はトナーの吹き出し防止に影響している。現像スリーブ１０２に付着して搬送される磁性トナー量を規制する部材として、弾性ブレード１０３が配設され弾性ブレード１０３の現像スリーブ１０２に対する当接圧により現像領域に搬送されるトナー量が制御される。現像領域では、感光ドラム１００と現像スリーブ１０２との間に直流及び交流現像バイアスが印加され、現像スリーブ上トナーは静電潜像に応じて感光ドラム１００上に飛翔し可視像となる。
【０１４５】
図７は、静電潜像担持体上のトナー像を中間転写体上に１次転写した後、中間転写体上のトナー像を記録材に２次転写するタイプの画像形成装置を示す。
【０１４６】
感光体１は、基材１ａ上に有機光半導体を有する感光層１ｂを有し、矢印方向に回転し、対抗し接触回転する帯電ローラー２（導電性弾性層２ａ，芯金２ｂ）により感光体１上に約−６００Ｖの表面電位に帯電させる。露光は、ポリゴンミラーにより感光体上にデジタル画像情報に応じてオン−オフさせることで露光部電位が−１００Ｖ，暗部電位が−６００Ｖの静電荷像が形成される。複数の現像器４−１，４−２，４−３，４−４を用い、マゼンタトナー，シアントナー，イエロートナーまたはブラックトナーを感光体１上に反転現像方法を用いトナー像を得た。該トナー像は、一色毎に中間転写体５（弾性層５ａ，支持体としての芯金５ｂ）上に転写され中間転写体５上に４色の色重ね顕色像が形成される。感光体１上の転写残トナーはクリーナー部材８により、残トナー容器９中に回収される。
【０１４７】
本発明に係わるトナーは、転写効率が高いため、簡単なバイアスローラー又はクリーナー部材のない系においても問題が発生しにくい。
【０１４８】
中間転写体５は、パイプ状の芯金５ｂ上にカーボンブラックの導電付与部材をニトリル−ブタジエンラバー（ＮＢＲ）中に十分分散させた弾性層５ａをコーティングした。該コート層の硬度は、ＪＩＳ Ｋ−６３０１に準拠し３０度で且つ体積固有抵抗値は、１０⁹Ω・ｃｍであった。感光体１から中間転写体５への転写に必要な転写電流は約５μＡであり、これは電源より＋２０００Ｖを芯金５ｂ上に付与することで得られた。中間転写体５から転写材６へトナー像を転写後に中間転写体表面をクリーナー部材１０でクリーニングしてもよい。
【０１４９】
転写ローラーは、２０ｍｍの芯金７ｂ上にカーボンの導電性付与部材をエチレン−プロピレン−ジエン系三元共重合体（ＥＰＤＭ）の発泡体中に十分分散させたものをコーティングすることにより生成した弾性層７ａの体積固有抵抗値が、１０⁶Ω・ｃｍで、ＪＩＳ Ｋ−６３０１基準の硬度が３５度の値を示すものを用いた。転写ローラーには電圧を印加して１５μＡの転写電流を流した。中間転写体５から転写材６にトナーを一括転写させる際の転写ローラー７上の汚染トナーは、クリーニング部材としてファーブラシクリーナーかクリーニング部材レス系が一般的に用いられる。
【０１５０】
また、本発明においては、現像器４−１，４−２，４−３，４−４のいずれか一つを磁性トナーを用いた磁性一成分ジャンピング現像方式とし、図２に示すような現像器構成を用いた。他の３つの非磁性カラートナー用現像器は、二成分磁性ブラシ現像器又は、非磁性一成分現像器を用いた。
【０１５１】
【実施例】
以下、本発明を製造例及び実施例により具体的に説明するが、これは本発明をなんら限定するものではない。尚、以下の配合における部数は全て重量部である。
【０１５２】
（トナー製造例１）

【０１５３】
上記材料をブレンダーにて混合し、１３０℃に加熱した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た。この時磁性トナー粒子は、図５に示すように粉砕工程で所定の粒度になるまで粉砕が繰り返される。次いで得られた微粉砕物を、コアンダ効果を用いた多分割分級機にて厳密に分級して磁性トナー分級粒子を得た。
【０１５４】
該磁性トナー分級粒子を、図８及び９に示す衝撃式表面処理装置を用いて、ローターを回転して機械的衝撃力を与える方式の表面改質装置を用いて、１６００ｒｐｍ（周速８０ｍ／ｓｅｃ）で３分間の表面処理を行ない、磁性トナー粒子を得た。表面改質装置には、表面改質時の装置内部温度を好ましい範囲に制御する目的で２０℃の冷却水を通水した。この時磁性トナー分級粒子を投入する前の処理装置内部気流温度は３０℃であり、磁性トナー分級粒子投入後、処理装置内部気流温度は徐々に上昇し、３分後には内部気流温度は最高５９℃に達した。
【０１５５】
分級した磁性トナー分級粒子の粒度分布における４μｍ以下の微粉の含有量は、１６個数％であり、処理後の磁性トナー粒子の４μｍ以下の微粉の含有量は、１９個数％であった。
【０１５６】
次いで、得られた磁性トナー粒子１００部に対し、シリコーンオイルとヘキサメチルジシラザンで疎水化処理された一次粒径１２ｎｍの乾式シリカ（処理後のＢＥＴ比表面積１２０ｍ²／ｇ）を１．２部添加し、混合機にて混合し磁性トナー１を得た。得られた磁性トナーの重量平均粒径は６．７μｍ、３μｍ以上の粒子においての円形度ａが０．９０以上の粒子は９６．７個数％、円形度ａが０．９８以上の粒子は２３．２個数％であった。３μｍ以上の粒子における円形度分布の標準偏差ＳＤは０．０３１であった。得られた磁性トナー１の物性を表１に示す。
【０１５７】
（トナー製造例２〜４）
トナー製造例１の表面改質装置の条件を変更する以外はトナー製造例１と同様にして磁性トナー２、３及び４を得た。得られた磁性トナー２、３及び４の物性を表１に示す。磁性トナー２、３及び４の粒度分布における微粉量（４μｍ以下の個数％）は、それぞれ２１％、１８．５％及び１８％であった。
【０１５８】
（トナー製造例５）

【０１５９】
上記材料を用いることを除いてはトナー製造例１と同様にして磁性トナー５を得た。得られた磁性トナーの重量平均粒径は６．７μｍ、３μｍ以上の粒子においての円形度ａが０．９０以上の粒子は９３．８個数％、円形度ａが０．９８以上の粒子は２２．２個数％であった。３μｍ以上の粒子における円形度分布の標準偏差ＳＤは０．０３６であった。処理時の内部気流温度はローターと粒子の衝撃による発熱で最高６０℃であった。得られた磁性トナー５の物性を表１に示す。
【０１６０】
（トナー製造例６）
トナー製造例１の表面改質装置の条件を１２００ｒｐｍ（周速６０ｍ／ｓｅｃ）で１分間に変更することを除いては、トナー製造例１と同様にして磁性トナー６を得た。得られた磁性トナー６の物性を表１に示す。
【０１６１】
（トナー製造例７）

【０１６２】
上記材料を用いること、表面改質装置の条件を１２００ｒｐｍ（周速６０ｍ／ｓｅｃ）で１分間に変更することを除いてはトナー製造例１と同様にして磁性トナー７を得た。得られた磁性トナー７の物性を表１に示す。
【０１６３】
（トナー製造例８）

【０１６４】
上記材料をブレンダーにて混合し、１３０℃に加熱した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、コアンダ効果を用いた多分割分級機にて厳密に分級して磁性トナー分級粒子を得た。
【０１６５】
次いで、得られた磁性トナー分級粒子１００部に対し、ヘキサメチルジシラザンで疎水化処理された一次粒径１６ｎｍの乾式シリカ（処理後のＢＥＴ比表面積１００ｍ²／ｇ）を０．８部添加し、混合機にて混合し磁性トナー８を得た。得られた磁性トナー８の物性を表１に示す。
【０１６６】
（トナー製造例９）
トナー製造例８で得たトナー分級粒子を用いて、３００℃熱風中を瞬間的に通過させる処理をおこなったことを除いてはトナー製造例８と同様にして、磁性トナー９を得た。得られた磁性トナー９の物性を表１に示す。
【０１６７】
（トナー製造例１０）
トナー製造例８で得たトナー分級粒子を用いて、表面改質装置の条件を１２００ｒｐｍ（周速６０ｍ／ｓｅｃ）で１分間に変更することを除いてはトナー製造例１と同様にして、磁性トナー１０を得た。得られた磁性トナー１０の物性を表１に示す。
【０１６８】
（トナー製造例１１）

【０１６９】
上記材料を用いることを除いてはトナー製造例１と同様にして磁性トナー１１を得た。得られた磁性トナーの重量平均粒径は６．９μｍ、３μｍ以上の粒子においての円形度ａが０．９０以上の粒子は９６．３個数％、円形度ａが０．９８以上の粒子は３２．０個数％であった。３μｍ以上の粒子における円形度分布の標準偏差ＳＤは０．０３６であった。処理時の内部気流温度はローターと粒子の衝撃による発熱で最高７３℃であった。得られた磁性トナー１１の物性を表１に示す。
【０１７０】
尚、処理時の、処理装置冷却水温を３０℃とした。
【０１７１】
（トナー製造例１２）

【０１７２】
上記材料を用いることを除いてはトナー製造例１と同様にして磁性トナー１２を得た。得られた磁性トナーの重量平均粒径は６．５μｍ、３μｍ以上の粒子においての円形度ａが０．９０以上の粒子は９０．２個数％、円形度ａが０．９８以上の粒子は８．５個数％であった。３μｍ以上の粒子における円形度分布の標準偏差ＳＤは０．０４７であった。処理時の内部気流温度はローターと粒子の衝撃による発熱で最高４５℃であった。得られた磁性トナー１２の物性を表１に示す。
【０１７３】
尚、磁性トナー１２の分級後の磁性トナー分級粒子の粒度分布における４μｍ以下の微粉の含有量は１５個数％であり、処理後の磁性トナー粒子の４μｍ以下の微粉の含有量は、２６個数％であった。
【０１７４】
（トナー製造例１３）

【０１７５】
上記材料を用いることを除いてはトナー製造例１と同様にして磁性トナー１３を得た。得られた磁性トナーの重量平均粒径は６．４μｍ、３μｍ以上の粒子においての円形度ａが０．９０以上の粒子は８７．０個数％、円形度ａが０．９８以上の粒子は４．５個数％であった。３μｍ以上の粒子における円形度分布の標準偏差ＳＤは０．０４６であった。処理時の内部気流温度はローターと粒子の衝撃による発熱で最高３７℃であった。得られた磁性トナー１３の物性を表１に示す。
【０１７６】
尚、磁性トナー１３の分級後の磁性トナー分級粒子の粒度分布における４μｍ以下の微粉の含有量は、１４個数％であり、処理後の磁性トナー粒子の４μｍ以下の微粉の含有量は、２７個数％であった。
【０１７７】
【表１】

【０１７８】
（感光体製造例１）
感光体としては直径３０ｍｍのＡｌシリンダーを基体とした。これに、図３に示すような構成の層を順次浸漬塗布により積層して、感光体を作製した。
【０１７９】
（１）導電性被覆層：酸化錫及び酸化チタンの粉末をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
【０１８０】
（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。
【０１８１】
（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。
【０１８２】
（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質量％添加し、均一に分散した。膜厚１５μｍ。水に対する接触角は９５度であった。
【０１８３】
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−Ｘ型を用いた。
【０１８４】
（感光体製造例２）
感光体製造例１でポリ４フッ化エチレン粉体を添加しないで同様に感光体を作製した。水に対する接触角は７４度であった。
【０１８５】
（感光体製造例３）
感光体は、電荷発生層までは感光体製造例１に準じて作製した。電荷輸送層は、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に１０：１０の質量比で溶解したものを用いた。膜厚２０μｍ。さらにその上に保護層として、同じ材料を５：１０の重量比で溶解した構成物にポリ４フッ化エチレン粉体（粒径０．２μｍ）を総固形分に対して３０％添加し、均一に分散したものを用い、電荷輸送層の上にスプレーコートした。膜厚５μｍ。水に対する接触角は１０２度であった。
【０１８６】
実施例１
画像形成装置として、概ね図１及び図２に示されるものを用いた。
【０１８７】
静電潜像担持体として感光体製造例３の有機感光体（ＯＰＣ）ドラムを用い暗部電位Ｖ_d＝−６５０Ｖ，明部電位Ｖ_L＝−２１０Ｖとした。感光ドラムと現像スリーブとの間隙を３００μｍとし、トナー担持体に、トナー規制部材として厚み１．０ｍｍ、自由長１０ｍｍのウレタンゴム製ブレードを１４．７Ｎ／ｍ（１５ｇ／ｃｍ）の線圧で当接させた。
【０１８８】
次いで、現像バイアスとして直流バイアス成分Ｖ_dc＝−５００Ｖ，重畳する交流バイアス成分Ｖ_P-P＝１５００Ｖ，ｆ＝２０００Ｈｚを用いた。
【０１８９】
図４のような転写ローラー（導電性カーボンを分散したエチレン−プロピレンゴム製、導電性弾性層の体積抵抗値１０⁸Ωｃｍ，表面ゴム硬度２４°，直径２０ｍｍ，当接圧４９Ｎ／ｍ（５０ｇ／ｃｍ）を感光体周速（４８ｍｍ／ｓｅｃ）に対して等速とし、転写バイアスを２〜２０μＡの間で振って転写性のラチチュードを評価した。トナーとして磁性トナー１を使用し、３２．５℃，８０％ＲＨ環境下で画出しを行なった。転写紙としては７５ｇ／ｍ²の紙を使用した。
【０１９０】
この時の感光体から転写材への転写効率９０％以上が得られる範囲は、４〜１８μＡと広い条件において、高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０１９１】
上記の転写効率は、５ｍｍ角のベタ黒部を転写材の中央と両端の３個所に印字し、転写材が定着器にいく前に、画像形成装置通過中に停止し、下記の方法で得た転写効率の３ヶ所の平均値である。
【０１９２】
転写効率は、感光体上の転写後の転写残トナーをマイラーテープによりテーピングして剥ぎ取り、紙上に貼ったもののマクベス濃度（ａ）、及び、転写紙上に転写されたトナー画像の上にマイラーテープ貼ったもののマクベス濃度（ｂ）から、紙上にテープのみ貼ったもののマクベス濃度（ｃ）をそれぞれ差し引いた数値を下記の通り、転写残濃度（Ａ）及び転写画像の濃度（Ｂ）とし、以下の式により算出した。
【０１９３】
転写残濃度（Ａ）＝濃度（ａ）−濃度（ｃ）
転写画像の濃度（Ｂ）＝濃度（ｂ）−濃度（ｃ）
転写効率（％）＝｛［転写画像の濃度（Ｂ）］／［転写残濃度（Ａ）＋転写画像の濃度（Ｂ）］｝×１００
【０１９４】
さらに、連続で６０００枚まで画出し、感光体削れ量を膜厚計で測定したところ、削れ量は０〜１μｍと非常に少なかった。
【０１９５】
実施例２
トナーとしてトナー２を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用したことを除いては実施例１と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率は９０％以上が得られる範囲は、４〜１７μＡと広い条件において高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０１９６】
実施例３
トナーとしてトナー３を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用したことを除いては実施例１と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率は９０％以上が得られる範囲は、４〜１６μＡと広い条件において高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０１９７】
実施例４
トナーとしてトナー４を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用したことを除いては実施例１と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率は９０％以上が得られる範囲は、４〜１４μＡと広い条件において高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０１９８】
実施例５
トナー５を使用し、実施例３と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率９０％以上が得られる範囲は、２〜１０μＡと実施例１よりやや悪かったものの、実用上時に問題はなく、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０１９９】
実施例６
トナー６を使用し、実施例３と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率９０％以上が得られる範囲は、２〜８μＡと実施例１よりやや悪く、ライン画像部分にわずかな中抜けが見られたものの、実用上特に問題はなく、画像上に飛び散りのない良好な画像が得られた。
【０２００】
参考例１
トナー７を使用し、実施例３と同様の装置・条件で画出しを行った。この時の感光体から転写材への転写効率９０％以上が得られる範囲は、２〜８μＡと実施例１よりやや悪く、画像上にやや飛び散りが見られたものの、実用上は問題のない良好な画像が得られた。
【０２０１】
参考例２
トナー１２を使用することを除いては、実施例２と同様の装置・条件で画出しを行なった。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は２〜６μＡと実施例１よりもやや悪く、画像上にやや飛び散りが見られたものの実用上問題のない良好な画像が得られた。
【０２０２】
比較例１
トナー８を使用することを除いては、実施例２と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は存在せず、トナーの利用効率が低かった。また、やや文字やラインの転写中抜けが目立つ画像であった。
【０２０３】
比較例２
トナー９を使用し、静電潜像担持体として感光体製造例２のＯＰＣドラムを使用したことを除いては比較例１と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率は９０％以上が得られる範囲は８μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が薄く貧弱な、飛び散りが非常に多い画像であった。さらに５００枚の画出しにより感光体クリーニング不良が発生した。
【０２０４】
比較例３
トナー１０を使用し、静電潜像担持体として感光体製造例２のＯＰＣドラムを使用したことを除いては比較例１と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率は９０％以上が得られる範囲は６μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が薄く貧弱な、飛び散りが非常に多い画像であった。
【０２０５】
比較例４
トナー９を使用することを除いては、実施例２と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率は９０％以上が得られる範囲は８μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が低く、１５℃，１０％環境下での画出し３００枚時にクリーニング不良が発生した。
【０２０６】
比較例５
トナー１０を使用することを除いては、実施例２と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は、６μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が低く、飛び散り、解像力、中抜けも劣ったものとなった。
【０２０７】
比較例６
トナー１１を使用することを除いては、実施例２と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は８〜９μＡと狭く、しかも画像濃度が低く、飛び散り、解像力、中抜けも劣ったものとなった。
【０２０８】
比較例７
トナー１３を使用することを除いては、実施例２と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は、６μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が低く、飛び散り、解像力、中抜けも劣ったものとなった。
【０２０９】
実施例７
画像形成装置として、概ね図１及び図２に示されるものを用いた。
【０２１０】
静電潜像担持体として感光体製造例３の有機感光体（ＯＰＣ）ドラムを用い暗部電位Ｖ_d＝−５５０Ｖ，明部電位Ｖ_L＝−２５０Ｖとした。感光ドラムと現像スリーブとの間隙を３００μｍとし、トナー担持体として下記の構成の層厚約７μｍ、ＪＩＳ中心線平均粗さ（Ｒａ）１．４μｍの樹脂層を、表面がブラスト処理した直径２０φのアルミニウム円筒上に形成した現像スリーブを使用し、現像磁極９５ｍＴ（９５０ガウス）、トナー規制部材として厚み１．０ｍｍ、自由長１０ｍｍのウレタンゴム製ブレードを１４．７Ｎ／ｍ（１５ｇ／ｃｍ）の線圧で当接させた。
【０２１１】
フェノール樹脂 １００部
グラファイト（粒径約７μｍ） ９０部
カーボンブラック １０部
【０２１２】
次いで、現像バイアスとして直流バイアス成分Ｖ_dc＝−４００Ｖ，重畳する交流バイアス成分Ｖ_P-P＝１５００Ｖ，ｆ＝２０００Ｈｚを用い、現像コントラスト（Ｖ_L−Ｖ_dc）１５０Ｖとして反転現像を行なった。
【０２１３】
図４のような転写ローラー（導電性カーボンを分散したエチレン−プロピレンゴム製、導電性弾性層の体積抵抗値１０⁸Ωｃｍ，表面ゴム硬度２４°，直径２０ｍｍ，当接圧４９Ｎ／ｍ（５０ｇ／ｃｍ）を感光体周速（４８ｍｍ／ｓｅｃ）に対して等速とし、印字を行なった。
【０２１４】
トナーとして磁性トナー１を使用し、１５℃，１０％ＲＨ環境下で連続７０００枚の画出しを行なったところ、表２に示すように充分なベタ画像濃度を維持し、画像上にゴースト、飛び散りや中抜けのない解像力の高い良好な画像が得られた。
【０２１５】
本実施例において飛び散りの評価は、グラフィカルな画像の画質に関わる微細な細線での飛び散り評価であり、文字やラインにおける飛び散りよりもより飛び散りやすい１００μｍ幅ラインでの飛び散り評価である。
【０２１６】
解像力は潜像電界によって電界が閉じ易く、再現しにくい図６に示す様な小径（Ｘ＝５０μｍφ）孤立ドットの再現性によって評価した。
【０２１７】
中抜けの評価は、中抜け現象が生じやすい厚紙（約１２８ｇ／ｃｍ²）に印字した際の評価である。
【０２１８】
さらに３２．５℃，８０％ＲＨ環境下で転写バイアスを２〜２０μＡの間で振って転写性のラチチュードを評価した。転写紙としては７５ｇ／ｃｍ²の紙を使用した。この時の感光体から転写材への転写効率９０％以上が得られる範囲は、４〜１８μＡと広い条件において高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。
【０２１９】
転写効率は、前述の算出方法を用いた。
【０２２０】
さらに、連続で６０００枚まで画出し、感光体削れ量を膜厚計で測定したところ、削れ量は０．５μｍと非常に少なかった。
【０２２１】
実施例８
トナーとしてトナー２を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用する以外は実施例７と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２２】
実施例９
トナーとしてトナー３を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用し暗部電位Ｖ_d＝−５５０Ｖ、明部電位Ｖ_L＝−１７０Ｖ、現像コントラスト（Ｖ_L−Ｖ_dc）＝２３０Ｖとすることを除いては実施例７と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２３】
実施例１０
トナーとしてトナー４を用い、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用したことを除いては実施例９と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２４】
実施例１１
トナー５を使用し、静電潜像担持体として感光体製造例１のＯＰＣドラムを使用し暗部電位Ｖ_d＝−４００Ｖ、明部電位Ｖ_L＝−１００Ｖとし、現像バイアスとして直流バイアス成分Ｖ_dc＝−３００Ｖ、重畳する交流バイアス成分Ｖ_P-P＝１６００Ｖ、ｆ＝１８００Ｈｚ、現像コントラスト（Ｖ_L−Ｖ_dc）＝２００Ｖとすることを除いては実施例９と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２５】
実施例１２
トナー６を使用し、実施例９と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２６】
参考例３
トナー７を使用し、実施例９と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０２２７】
参考例４
トナー１２を使用し、実施例９と同様の装置・条件で画出しを行った。その結果、表２に示す通り、実用上問題のない良好な画像が得られた。
【０２２８】
比較例８
トナー８を使用することを除いては、実施例８と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は存在せず、トナーの利用効率が低かった。また、やや文字やラインの転写中抜けが目立つ画像であった。
【０２２９】
比較例９
トナー９を使用し、静電潜像担持体として感光体製造例２のＯＰＣドラムを使用したことを除いては比較例８と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率は９０％以上が得られる範囲は８μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が薄く貧弱な、飛び散りが非常に多い画像であった。さらに５００枚の画出しにより感光体クリーニング不良が発生した。
【０２３０】
比較例１０
トナー１０を使用し、静電潜像担持体として感光体製造例２のＯＰＣドラムを使用したことを除いては比較例８と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率は９０％以上が得られる範囲は６μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が薄く貧弱な、飛び散りが非常に多い画像であった。
【０２３１】
比較例１１
トナー９を使用することを除いては、実施例８と同様の装置・条件で画出しを行った。その結果、表２に示す通り、低温低湿下の耐久評価において１０００枚時にクリーニング不良を発生した。また、転写ラチチュードも狭いものであった。
【０２３２】
比較例１２
トナー１０を使用することを除いては、実施例８と同様の装置・条件で画出しを行った。その結果、表２に示す通り、画像濃度が低く、飛び散り、解像力、中抜けも劣ったものであった。また、転写ラチチュードも狭いものであった。
【０２３３】
比較例１３
トナー１１を使用することを除いては、実施例８と同様の装置・条件で画出しを行った。その結果、表２に示す通り、画像濃度が低く、飛び散り、解像力、中抜けも劣ったものであった。
【０２３４】
比較例１４
トナー１３を使用することを除いては、実施例８と同様の装置・条件で画出しを行った。その結果、表２に示す通り、画像濃度が低く、飛び散り、解像力、中抜けも劣ったものであった。また、転写ラチチュードも狭いものであった。
【０２３５】
【表２】

【０２３６】
＊１ 飛び散りの評価において、Ａは極めて良好、Ｂは良好、Ｃは飛び散りが目立つ
＊２ 解像力の評価において、Ａは極めて良好、Ｂは良好、Ｃは解像不充分
＊３ 中抜けの評価において、Ａは極めて良好、Ｂは良好、Ｃは中抜けが目立つ
【０２３７】
実施例１３
画像形成装置として、概ね図７に示されるものを用いた。
【０２３８】
カラートナーとしては、キヤノンＬＢＰ−２０３０用シアントナー、マゼンタトナー及びイエロートナーを用い、それぞれ非磁性一成分現像器を用い現像を行った。
【０２３９】
感光体としては、感光体製造例１のものを用いた。
【０２４０】
磁性トナーとしては、トナー２を用いた。
【０２４１】
カラートナー３色重ねの画像の９０％以上転写率の転写電流範囲は、１２〜２０μＡであった。また、単色磁性トナー２画像の転写電流範囲は４〜１８μＡであった。
【０２４２】
上記構成の磁性トナーを入れ４色フルカラー画像において転写電流値１５μＡで、問題ない良好な画像が得られた。
【０２４３】
比較例１５
実施例１３と同様に、磁性トナーのみを１０に変更し、評価を行った。４色フルカラー画像で黒トナーのみが中抜け、解像度が劣り、転写性の悪いものとなった。
【０２４４】
【発明の効果】
本発明によれば、示差熱分析における吸熱ピークを１２０℃以下にひとつ以上有するトナーであり、該トナーの粒径３μｍ以上のトナーにおいて、円形度ａが０．９０以上のトナーを９０個数％以上有し、かつ、円形度ａが０．９８以上のトナーを３０個数％未満有していることを特徴とするトナーを用いることで、高画像濃度・潜像再現性を保持しつつ、再転写を起こさず、高品位で鮮鋭な画像が得られる。
【０２４５】
特に従来の磁性トナーと比較して幅広い転写ラチチュードが得られる。
【図面の簡単な説明】
【図１】本発明に好適な画像形成装置の一例を示す概略図である。
【図２】一成分現像用現像器の一例を示す概略図である。
【図３】本発明に用いる感光体の構成の一例を示す概略図である。
【図４】当接転写手段の一例を示す概略図である。
【図５】本発明のトナーを得るのに好適なトナー粉砕工程の一例を示す図である。
【図６】解像性評価に用いた孤立ドットパターンの例を示す図である。
【図７】本発明に好適な他の画像形成装置の一例を示す概略図である。
【図８】トナーの円形度をコントロールするための処理システムの一例を示す説明図である。
【図９】図８のシステムにおける衝撃式表面処理装置を示す説明図である。
【符号の説明】
１００ 感光体（静電潜像担持体）
１０２ 現像スリーブ（トナー担持体）
１０３ 当接ブレード
１０４ マグネットローラー
１１４ 転写帯電ローラー
１１６ クリーナー
１１７ 一次帯電ローラー
１４０ 現像器
１４１ 撹拌棒[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic charge image developing toner and an image forming method used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, or the like. More particularly, the present invention relates to an electrostatic charge image developing toner and an image forming method used in a copying machine, a printer, and a fax machine in which a toner image is previously formed on an electrostatic latent image carrier and then transferred onto a transfer material to form an image. .
[0002]
[Prior art]
Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive material is used to form an electric latent image on a photoreceptor by various means, and then the latent image is converted into a toner. The toner image is developed into a visible image and, if necessary, the toner image is transferred onto a transfer material such as paper, and then the toner image is fixed on the transfer material by heat / pressure to obtain a final image.
[0003]
In recent years, image forming apparatuses such as copying machines, printers, and fax machines using electrophotography have been increasingly demanded for colorization. In general, a color toner is a non-magnetic toner because it is difficult to use a magnetic toner containing a magnetic material because of its color. When the magnetic toner is used as the black toner and the non-magnetic toner is used as the color toner, the non-magnetic toner tends to have an optimum transfer current value higher than the optimum transfer current value of the magnetic toner. When the transfer conditions of the main body of the device are set to non-magnetic toner, the magnetic toner once undergoes a phenomenon called “retransfer” in which the toner once transferred onto the transfer material returns to the latent image carrier. Causes a decrease in concentration.
[0004]
In recent years, with further diversification of paper materials, copiers, printers, and fax machines using electrophotography are required to be compatible with these various paper materials. However, the optimum transfer conditions differ depending on the paper material that is the transfer material. For example, the optimum transfer current value is high for thick paper and overhead projector film (OHP film), and the optimum transfer current value is low for thin paper. Therefore, if the transfer conditions of the device main body are optimized for cardboard and OHP film, the “retransfer” phenomenon occurs when transferring to thin paper.
[0005]
Japanese Patent Application Laid-Open No. 61-279864 proposes a toner that defines shape factors SF-1 and SF-2. However, this publication has no description regarding transfer, and as a result of transfer using the toner described in the examples, transfer efficiency is not sufficient, and further improvement is required.
[0006]
Further, Japanese Patent Laid-Open No. 63-235953 proposes a magnetic toner that has been spheroidized by a mechanical impact force. However, the transfer efficiency is still insufficient and further improvement is necessary.
[0007]
As for printer devices, LED and LBP printers have become the mainstream in the recent market, and the direction of technology is higher resolution, that is, what was conventionally 240 or 300 dpi has become 400, 600 or 800 dpi. Accordingly, the development method is also required to have higher definition.
[0008]
Copiers are also becoming more sophisticated, and are therefore moving toward digitalization. Since the digital method is mainly a method of forming an electrostatic charge image with a laser, it is also progressing in the direction of high resolution, and here again, a high-resolution and high-definition developing method has been required as in the case of a printer. .
[0009]
From this point of view, especially in digital printers and copiers, the photosensitive layer has been made thinner for the purpose of increasing the definition of the electrostatic latent image. When such a thin film photoconductor is used, the potential contrast of the electrostatic latent image is lowered, so that a toner having higher developability is desired as a toner used for development.
[0010]
In recent years, from the viewpoint of environmental protection, a primary charging process and a transfer process using a photosensitive member contact member are becoming mainstream from a conventionally used primary charging process and a transfer process using corona discharge.
[0011]
For example, Japanese Patent Laid-Open Nos. 63-149669 and 2-123385 have been proposed. These are related to the contact charging method and the contact transfer method. The electrostatic latent image carrier is brought into contact with the electrostatic latent image carrier while a voltage is applied to the conductive elastic roller. After uniformly charging and then obtaining a toner image by an exposure process and a development process, the electrostatic latent image carrier and the electrostatic latent image carrier are pressed while pressing another transfer conductive elastic roller to which a voltage is applied to the electrostatic latent image carrier. A transfer material is passed between the transfer conductive elastic roller and the toner image on the electrostatic latent image carrier is transferred to the transfer material, and a transfer image is obtained through a fixing step.
[0012]
However, in such a contact transfer method that does not use corona discharge, a transfer member such as a roller is brought into contact with the electrostatic latent image carrier through a transfer material during transfer, and therefore, on the electrostatic latent image carrier. When the formed toner image is transferred to a transfer material, the toner image is pressed against the transfer material, causing a problem of partial transfer failure called “transfer skipping”.
[0013]
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 electrostatic latent image carrier becomes larger than the Coulomb force applied to the toner particles during transfer. As a result, there was a tendency for the transfer residual toner to increase.
[0014]
Furthermore, in the roller charging method, the physical and chemical action on the surface of the electrostatic latent image carrier due to the discharge generated between the charging roller and the electrostatic latent image carrier is larger than in the corona charging method, In particular, when the combination of the organic photoreceptor / blade cleaning is used, wear due to deterioration of the surface of the organic photoreceptor tends to occur, and there is a problem in life. However, the combination of contact charging / organic photoconductor / one-component magnetic developing method / contact transfer / blade cleaning is easy to reduce the cost and size and weight of the image forming apparatus, so that low cost, small size and light weight are required. This is the mainstream method for copiers, printers, and facsimiles.
[0015]
Therefore, the toner and the electrostatic latent image carrier used in such an image forming method are required to have excellent releasability.
[0016]
[Problems to be solved by the invention]
An object of the present invention is to provide an electrostatic charge image developing toner and an image forming method which have solved the above-mentioned problems of the prior art.
[0017]
An object of the present invention is to provide a toner for developing an electrostatic charge image and an image forming method capable of obtaining a high image density without causing “retransfer” under a wide range of transfer current conditions (particularly under high transfer current conditions).
[0018]
An object of the present invention is an image that has an excellent developing ability even for an electrostatic latent image having a lower latent image contrast, has a high image density, and faithfully develops a small spot latent image to obtain a sharp image. It is to provide a forming method.
[0019]
An object of the present invention is to provide an electrostatic charge image developing toner and an image forming method that are excellent in transferability, have little transfer residual toner, and that do not cause transfer omission even in a roller transfer system, or in which these phenomena are suppressed. There is to do.
[0020]
An object of the present invention is an electrostatic charge image developing toner and an image which are excellent in releasability and slipperiness, have these functions for a long period of time, and have little photoconductor abrasion even after printing a large number of sheets. It is to provide a forming method.
[0021]
An object of the present invention is to provide an electrostatic charge image forming toner and an image forming method in which charging abnormality or image defect due to contamination of a member pressed against an electrostatic latent image carrier does not occur or these phenomena are suppressed. There is.
[0022]
[Means for Solving the Problems]
The present invention relates to a toner for developing an electrostatic image having at least a toner particle containing a binder resin and a colorant, and an inorganic fine powder.
The toner has an endothermic peak in differential thermal analysis.60 ° C to 120 ° CThe toner has at least one particle in a temperature range of 90% by number of particles having a particle size of 3 μm or more and a circularity a obtained by the following formula of 0.90 or more, and a circular shape. Less than 30% by number of particles having a degree of 0.98 or moreAnd
The toner has a standard deviation SD of a circularity distribution obtained from the following formula of particles having a particle diameter of 3 μm or more of 0.045 or less,
The toner has a weight average particle diameter of 8.0 μm or less,
The toner is subjected to a spheronization process that applies at least a mechanical impact force in a toner manufacturing process having at least a melting / kneading process and a grinding process.The present invention relates to a toner for developing an electrostatic charge image.
[0023]
[Expression 7]

[0024]
The present invention also includes a step of charging the electrostatic latent image carrier;
Forming an electrostatic latent image on the charged electrostatic latent image carrier;
Developing the electrostatic latent image with toner carried on the toner carrier to form a toner image on the electrostatic latent image carrier; and
A step of bringing a transfer member to which a voltage is applied into contact with the transfer material to transfer the toner image on the electrostatic latent image carrier onto the transfer material;
In an image forming method having
The toner has at least toner particles containing at least a binder resin and a colorant, and inorganic fine powder,
The toner isEndothermic peaks in differential thermal analysis60 ° C to 120 ° CHave one or more in the temperature range,
The toner is,In particles having a particle size of 3 μm or more, 90% by number or more of particles having a circularity a of 0.90 or more obtained from the above formula and less than 30% by number of particles having a circularity a of 0.98 or more TheAnd
The toner has a standard deviation SD of a circularity distribution obtained from the above formula of 0.045 or less for particles having a particle diameter of 3 μm or more.
The toner has a weight average particle diameter of 8.0 μm or less,
The toner is subjected to a spheroidizing process that applies at least a mechanical impact force in a toner manufacturing process having at least a melting / kneading process and a pulverizing process.The present invention relates to an image forming method.
[0025]
Furthermore, the present invention includes a step of charging the electrostatic latent image carrier;
Forming an electrostatic latent image on the charged electrostatic latent image carrier;
Developing the electrostatic latent image with toner carried on the toner carrier to form a toner image on the electrostatic latent image carrier;
Primary transfer of a toner image on the electrostatic latent image carrier to an intermediate transfer member; and
A step of bringing a transfer member to which a voltage is applied into contact with the recording material to secondarily transfer the toner image on the intermediate transfer member to the recording material;
In an image forming method having
The toner has at least toner particles containing at least a binder resin and a colorant, and inorganic fine powder,
The toner isEndothermic peaks in differential thermal analysis60 ° C to 120 ° CThe toner has at least one particle having a particle diameter of 3 μm or more and 90% by number or more of particles having a circularity a obtained from the above formula of 0.90 or more. less than 30% by number of particles having a of 0.98 or moreAnd
The toner has a standard deviation SD of a circularity distribution obtained from the above formula of 0.045 or less for particles having a particle diameter of 3 μm or more.
The toner has a weight average particle diameter of 8.0 μm or less,
The toner is subjected to a spheroidizing process that applies at least a mechanical impact force in a toner manufacturing process having at least a melting / kneading process and a pulverizing process.The present invention relates to an image forming method.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
The circularity in the present invention is used as a simple method for quantitatively expressing the shape of particles, and in the present invention, measurement is performed using a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, The value obtained from the following formula (1) is defined as circularity.
[0027]
[Equation 8]

[0028]
As a specific measuring method, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the shape and particle size of the toner are measured with the above apparatus at a dispersion concentration of 3000 to 10,000 / μl.
[0029]
The circularity in the present invention is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.
[0030]
Further, in the present invention, the standard deviation SD of the circularity distribution uses a value obtained by the following formula (2) from the circularity and average circularity of each particle.
[0031]
[Equation 9]

[0032]
The SD of the circularity distribution in the present invention is an index of the breadth of the distribution. The smaller the numerical value, the sharper the distribution is.
[0033]
The present inventors have investigated the relationship between the distribution of the circularity of the toner and the transferability, and found that there is a very deep relationship, which has led to the present invention.
[0034]
In the toner of the present invention, among particles having a particle diameter of 3 μm or more, 90% or more (90 to 100%), more preferably 93 or more (93 to 100%) of particles having a circularity a of 0.90 or more. And particles having a circularity a of 0.98 or more are preferably less than 30% by number (0 to less than 30% by number), more preferably particles having a toner particle size of 3 μm or more. When the standard deviation SD of the circularity distribution at 0.04 is 0.045 or less (0 <SD ≦ 0.045), more preferably 0.040 or less (0 <SD ≦ 0.040), the above problem can be solved without any harmful effects. it can.
[0035]
When the content of particles having a circularity a of 0.90 or more of the toner is less than 90% by number, the transfer efficiency of the toner image during transfer from the electrostatic latent image carrier to the transfer material is reduced. This is not preferable because the transfer of the line is lost. Further, if the content of particles having a circularity a of 0.98 or more exceeds 30% by number, a cleaning failure tends to occur.
[0036]
Further, when the standard deviation SD of the circularity distribution in the toner having a particle diameter of 3 μm or more is 0.045 or less, further excellent transferability can be obtained.
[0037]
The reason is that when a toner thin layer is formed on the toner carrier in the development process, a sufficient toner coat amount can be maintained even if the regulating force of the toner layer thickness regulating member is made stronger than usual. This is because the charge amount of the toner on the toner carrier can be made higher than usual without damaging the toner carrier.
[0038]
For this reason, the developing capability for a low potential latent image having a potential contrast of 400 V or less, further 350 V or less, which has been difficult in the past, is greatly improved. This is particularly effective when developing a digital microspot latent image.
[0039]
Furthermore, it is easy to obtain a high image density without causing “re-transfer” even in the case of a magnetic toner at the same wide transfer current conditions (particularly high transfer current conditions) as in the case of a non-magnetic toner.
[0040]
In general, magnetic toner has a lower resistance than non-magnetic toner, and the transfer current condition is set lower for magnetic toner and higher for non-magnetic toner.
[0041]
In recent years, as a method for obtaining a full-color image, a combination of black toner, which is excellent in durability stability in a single color and easy to extend the life, as a magnetic toner and other color toner as a non-magnetic toner has been attracting attention.
[0042]
By using the present invention for a magnetic toner in a full-color image forming method combining a magnetic toner and a non-magnetic toner, or for both a magnetic toner and a non-magnetic toner, the transfer current condition can be set to the same level as that of a non-magnetic toner. It becomes possible to take.
[0043]
Therefore, in the image forming method using the intermediate transfer member described later, the toner composition of the present invention is used as the magnetic toner, and the magnetic toner is selected from the group consisting of nonmagnetic cyan toner, nonmagnetic yellow toner, and nonmagnetic magenta toner. The magnetic toner and the non-magnetic color toner, which are used together with the one or more kinds of non-magnetic color toners to be primarily transferred from the electrostatic latent image carrier sequentially onto the intermediate transfer member, and are primarily transferred onto the intermediate transfer member. When a color toner image combined with is collectively transferred to a recording material, even if the transfer is performed under a higher transfer current condition suitable for the non-magnetic color toner, the magnetic toner is transferred as well as the non-magnetic color toner. For this reason, transfer defects are unlikely to occur.
[0044]
The toner of the present invention has one or more endothermic peaks in the differential thermal analysis of the toner in a temperature range of 120 ° C. or lower, preferably 110 ° C. or lower.
[0045]
When the endothermic peak in the differential thermal analysis of the toner is not in the temperature range of 120 ° C. or less, the effect of the present invention cannot be obtained sufficiently.
[0046]
That is, a toner having an endothermic peak in a differential thermal analysis of the toner in a temperature range of 120 ° C. or less has an endothermic peak in the state of dispersion of the magnetic substance and the charge control agent in the binder resin in the melt-kneading step in the production. Unlike a toner that does not have a temperature in the temperature range of 120 ° C. or lower, it is presumed that the toner has a “specific state”. It is presumed that such a specific state affects the surface properties of the toner of the present invention and makes it easy to exhibit the effect of improving transferability.
[0047]
That is, the toner has an endothermic peak in the differential thermal analysis of the toner in a temperature range of 120 ° C. or less, so that the specific circularity distribution of the toner can be easily achieved. When processing that applies mechanical impact force to the toner is required to achieve a specific circularity distribution, it has the effect of moderately maintaining the temperature rise in the device, and causes toner fusion to the device. Therefore, an appropriate toner surface property can be obtained.
[0048]
In the present invention, the toner is effective if it has at least one endothermic peak in the differential thermal analysis of the toner in a temperature range of 120 ° C. or lower, and further has another endothermic peak in a temperature range higher than 120 ° C. It does not matter. In the present invention, it is more preferable that the toner does not have an endothermic peak in the differential thermal analysis of the toner in a temperature range of 60 ° C. or lower, preferably 70 ° C. or lower. When the toner has an endothermic peak in a differential thermal analysis of the toner in a temperature range of 60 ° C. or lower, the image density tends to be low, and the storage stability tends to be unstable.
[0049]
As a means for making the toner have a form having an endothermic peak in the differential thermal analysis of the toner in a temperature range of 120 ° C. or less, a compound having an endothermic peak in the differential thermal analysis in the temperature range of 120 ° C. or less is contained in the toner. The method of adding is preferable.
[0050]
Examples of the substance having one or more endothermic peaks in the differential thermal analysis in a temperature range of 120 ° C. or lower include resins and waxes.
[0051]
Examples of the resin include a crystalline polyester resin and a silicone resin.
[0052]
Examples of the wax include petroleum waxes such as paraffin wax, microcrystalline wax and petrolactam and derivatives thereof; montan wax and derivatives thereof; hydrocarbon waxes and derivatives thereof according to Fischer-Tropsch method; polyolefin waxes and derivatives thereof typified by polyethylene; Natural waxes such as carnauba wax and candelilla wax and derivatives thereof; alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or derivatives thereof; acid amides and derivatives thereof, esters and derivatives thereof, ketones and derivatives thereof , Hydrogenated castor oil and derivatives thereof; vegetable waxes; animal waxes.
[0053]
The above derivatives include block copolymers or graft modified products of oxides and vinyl monomers.
[0054]
Among these, polyolefin, Fischer-Tropsch hydrocarbon wax, petroleum-based wax or higher alcohol has the effect of stabilizing the charge of the toner base, and is further preferable for the toner of the present invention because the effect of preventing retransfer is further enhanced.
[0055]
When the above specific compound is used, the effect of preventing “retransfer” is further enhanced.
[0056]
These compounds are relatively low in polarity and are considered to stabilize the charging of the toner.
[0057]
The compound having an endothermic peak in a differential thermal analysis in a temperature range of 120 ° C. or lower is a wax selected from the group consisting of polyolefin, hydrocarbon wax by Fischer-Tropsch method, petroleum wax, and higher alcohol, and GPC of this wax When the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in the measurement is 1.0 to 2.0, more preferably 1.0 to 1.5, “retransfer” The effect of prevention is further enhanced.
[0058]
By adding the above wax having a very sharp molecular weight distribution in which the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.0 to 2.0, This is considered to be because the state of dispersion of the magnetic substance and the charge control agent in the binder resin becomes more preferable in the melt-kneading step in the production.
[0059]
For the measurement of the endothermic peak of the toner according to the present invention, a DSC curve measured by a differential scanning calorimeter of high accuracy internal heat input compensation type such as DSC-7 manufactured by PerkinElmer is used.
[0060]
The measurement method is performed according to ASTM D3418-82. The DSC curve used in the present invention is a DSC curve that is measured when the temperature is lowered once and the temperature is raised in the range of a temperature rate of 10 ° C./min and a temperature of 0 to 200 ° C. .
[0061]
The endothermic peak temperature is a peak temperature in a positive direction in the DSC curve, that is, a point at which the differential value of the peak curve becomes 0 when changing from positive to negative.
[0062]
In the present invention, the toner preferably has a main peak in the molecular weight region exceeding the molecular weight of 15,000 in the molecular weight distribution by GPC measurement of the binder resin in order to control the standard deviation of the circularity distribution of the toner, and more preferably the molecular weight. The proportion of the component of 10,000 or less is preferably 25% or less, more preferably 20% or less.
[0063]
In the molecular weight distribution by GPC measurement of the binder resin of the toner, when the main peak exists in the molecular weight region having a molecular weight of 15000 or less, or when the proportion of the component having a molecular weight of 10,000 or less exceeds 25%, Since the toner tends to be brittle and pulverized more than necessary, the circularity distribution of the toner tends to be wide and difficult to control within the range defined in the present invention. Such a member in contact with the toner tends to be easily contaminated and fused by the toner, and is liable to cause a charging failure and an image defect.
[0064]
In particular, when the toner is spheroidized by applying a mechanical impact force after pulverizing the toner, if the main peak exists in the molecular weight region exceeding the molecular weight of 15000, the degree of circularity of the toner is aligned to some extent when the pulverization process is completed. It is possible to maintain the circularity distribution in the range specified in the present invention by the subsequent spheronization treatment, which is preferable in terms of transferability, and further, a member such as an image carrier that contacts the toner This is preferable from the viewpoint of improving durability because it can prevent fouling by toner.
[0065]
It is more preferable not to have a peak or a shoulder in a molecular weight region having a molecular weight of 15000 or less because generation of super fine powder of toner that adversely affects development in a spheronization processing step in which mechanical impact force is applied can be suppressed.
[0066]
That is, as shown in FIG. 5, the toner of the present invention melts and kneads the toner raw material in the melting and kneading step, coarsely pulverizes the kneaded product in the coarse pulverizing step, finely pulverizes the coarsely pulverized product in the fine pulverizing step, The finely pulverized product is divided into particles having a prescribed particle size and particles having a prescribed particle size in the first classification step, and the particles having the prescribed particle size are further in the prescribed particle size range in the second classification step. The toner particles obtained by spheronizing the classified product within the predetermined particle size range in the spheronization process step are obtained while the particles having a particle size larger than the specified particle size in the first classification step are It is manufactured by a manufacturing method that is introduced into the pulverization step and the subsequent steps are performed.
[0067]
In such a manufacturing method, in the case of a toner containing a hard binder resin in which the main peak exists in a molecular weight region exceeding the molecular weight of 15,000 in the molecular weight distribution by GPC measurement of the binder resin of the toner as described above, Since it is difficult to pulverize in the fine pulverization step, many particles return to the fine pulverization step again after classification in the first classification step, and are usually repeatedly introduced into the fine pulverization step a plurality of times.
[0068]
By repeating this pulverization process a plurality of times, the spheroidized product before being introduced into the spheronization treatment process is appropriately spheroidized and the degree of circularity is appropriately aligned. The circularity distribution of the toner obtained through the heat treatment step can be preferably adjusted within the range defined by the present invention. In particular, in the case of a toner having a small particle diameter, the number of times of introduction into the fine pulverization step increases, so that the circularity can be made more uniform.
[0069]
In the present invention, the molecular weight distribution of the binder resin of the toner is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, a sample in which toner was previously extracted with a THF (tetrahydrofuran) solvent using a Soxhlet extractor for 20 hours was used, and the column configuration was A-801, 802, 803, 804, manufactured by Showa Denko. 805, 806, and 807 are connected, and a molecular weight distribution can be measured using a standard polystyrene resin calibration curve.
[0070]
The binder resin used in the present invention includes, for example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene, and a substituted polymer thereof; styrene-p-chlorostyrene copolymer, styrene. -Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrenic copolymers such as coalesced; Vinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl Butyral, terpene resin, coumarone indene resin and petroleum resin can be used. Cross-linked styrene resins are also preferred binder resins.
[0071]
Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or a substituted product thereof; for example, maleic acid, butyl maleate, Dicarboxylic acids having a double bond such as methyl maleate and dimethyl maleate and substituted products thereof; for example, vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; Ethylenic olefins such as alkylene; for example, vinyl methyl ketone, vinyl ketones such as vinyl hexyl ketone; for example, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether; and the like. These vinyl monomers are used alone or in combination.
[0072]
Here, as the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol diethylene Carboxylates having two double bonds, such as methacrylate and 1,3-butanediol dimethacrylate; divinyl compounds of divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups; Can be used alone or as a mixture.
[0073]
Binder resins for toner used for pressure fixing include low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, higher fatty acid, polyamide resin and polyester resin. Can be mentioned. These are preferably used alone or in combination.
[0074]
In the toner of the present invention, it is preferable to use a charge control agent blended with toner particles (internal addition) or mixed with toner particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, in the toner of the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. The negative charge control agent for controlling the toner to negative charge includes the following substances.
[0075]
For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid metal complexes. Others include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenols.
[0076]
The following substances are used as positive charge control agents for controlling the toner to positive charge.
[0077]
For example, modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs of phosphonium salts thereof. Onium salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide) Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexane Such as diorgano tin borate such Rusuzuboreto; there is.
[0078]
These charge control agents can be used alone or in combination of two or more.
[0079]
The above-described charge control agent is preferably used in the form of fine particles. In this case, the number average particle diameter of these charge control agents is particularly preferably 4 μm or less, and more preferably 3 μm or less. When these charge control agents are internally added to the toner, they are preferably contained in the toner in an amount of 0.1 to 20 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin.
[0080]
The colorant used in the present invention was combined so that the black colorant was adjusted to black by a chromatic colorant such as carbon black, a magnetic material, a yellow colorant, a magenta colorant, and a cyan colorant shown below. Things are used.
[0081]
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, 97, 109, 110, 111, 120, 127, 128, 129, 147, 168, 174, 176, 180, 181 and 191 are preferably used.
[0082]
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.
[0083]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds 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.
[0084]
These colorants can be used alone or in combination and further in the form of a solid solution. In the present invention, the colorant is selected in consideration of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. These chromatic colorants are contained in 1 to 20 parts by weight of the toner with respect to 100 parts by weight of the binder resin.
[0085]
Examples of the magnetic material include a metal oxide containing an element of iron, cobalt, nickel, copper, magnesium, manganese, aluminum, or silicon. Of these, those mainly composed of iron oxide such as triiron tetroxide and γ-iron oxide are preferred. From the viewpoint of toner chargeability control, other elements such as silicon element or aluminum element may be contained. These magnetic particles preferably have a BET specific surface area by nitrogen adsorption method of 2 to 30 m.²/ G, especially 3 to 28m²/ G, and magnetic powder having a Mohs hardness of 5 to 7 is preferred.
[0086]
As the shape of the magnetic material, there are octahedron, hexahedron, sphere, needle shape, scale shape, etc., but the shape with less anisotropy such as octahedron, hexahedron, sphere, and indefinite shape increases the image density. Preferred above. The average particle size of the magnetic material is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and still more preferably 0.1 to 0.4 μm.
[0087]
The content of the magnetic material is preferably 30 to 200 parts by weight, more preferably 40 to 200 parts by weight, and still more preferably 50 to 150 parts by weight with respect to 100 parts by weight of the binder resin. If the amount is less than 30 parts by weight, in a developing device that uses magnetic force for toner conveyance, the conveyance performance is insufficient, and the developer layer on the developer carrying member tends to become uneven, resulting in image unevenness, and further increase in developer tribo. The image density tends to decrease due to the above. When the content exceeded 200 parts by weight, there was a tendency for problems to occur in the fixing property.
[0088]
In the toner of the present invention, known inorganic fine powders to be contained together with the toner particles can be used, but silica, alumina, titania or the like can be used for improving charging stability, developability, fluidity and storage stability. It is preferable to be selected from double oxides. Further, silica is more preferable. For example, silica can be used both so-called dry silica produced by vapor phase oxidation of silicon halides and alkoxides, or dry silica called fumed silica and so-called wet silica produced from alkoxide, water glass, etc. However, there are few silanol groups on the surface and inside the silica fine powder, and Na₂O, SO_Three ^2-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. They are also included.
[0089]
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 50-400m²Those in the / g range give good results.
[0090]
The content of the inorganic fine powder in the toner is preferably 0.1 to 8 parts by weight, more preferably 0.5 to 5 parts by weight, still more preferably more than 1.0, based on 100 parts by weight of the toner. It should be up to 0 part by weight.
[0091]
The inorganic fine powder used in the present invention is a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a silane cup having a functional group, if necessary, for the purpose of hydrophobicity and chargeability control. It is preferable that the treating agent such as a ring agent, other organic silicon compound, or organic titanium compound is used alone or in combination.
[0092]
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.
[0093]
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.
[0094]
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. Polishing agent such as strontium acid powder; fluidity imparting agent such as titanium oxide powder and aluminum oxide powder; anti-caking agent; conductivity imparting agent such as carbon black powder, zinc oxide powder and tin oxide powder; It is also possible to use developability improvers such as fine particles and inorganic particles of opposite polarity.
[0095]
In order to produce the toner according to the present invention, for example, a binder resin, a wax, a metal salt or metal complex, a pigment as a colorant, a dye, or a magnetic substance, and if necessary, a charge control agent and other additives are added. After thoroughly mixing with a mixer such as a Henschel mixer or ball mill, and then melt-kneading using a heat kneader such as a heating roll, kneader, or extruder, and the resins are mutually compatible, metal compounds, pigments, dyes A method of dispersing and dissolving the magnetic material, cooling and solidifying and pulverizing, obtaining toner particles by performing classification and surface treatment as necessary, and adding and mixing inorganic fine powder or the like as necessary is preferably used. .
[0096]
In order to achieve a specific circularity distribution of the toner of the present invention, a general pulverizer such as a mechanical impact pulverizer and a jet pulverizer is used for a toner having one or more endothermic peaks in differential thermal analysis at 120 ° C. or lower. Although it may be simply pulverized (classified as necessary) by the method used, it is possible to obtain a sharper circularity distribution and a wider latitude of transfer conditions by further applying a mechanical impact as a supplement. This is preferable.
[0097]
A hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water or a method in which the toner particles pass through a hot air stream may be used. In view of image characteristics and productivity, the method of applying a process by mechanical impact force is most preferable.
[0098]
Examples of the process for applying mechanical impact force include a method using a mechanical impact type pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry Co .; or a mechano-fusion system manufactured by Hosokawa Micron Co., Ltd. or Nara Machinery. And a method of applying a mechanical impact force to the toner by a compressive force and a frictional force by pressing the toner to the inside of the casing by a centrifugal force with a blade rotating at high speed as in a device such as a hybridization system manufactured by Seisakusho.
[0099]
In the present invention, a processing system using an impact surface processing apparatus for controlling the circularity of toner will be described with reference to FIGS.
[0100]
51 is a main body casing, 58 is a stator, 77 is a stator jacket, 63 is a recycling pipe, 59 is a discharge valve, 19 is a discharge chute, and 64 is a raw material hopper.
[0101]
In the impact surface treatment apparatus, as shown in FIGS. 8 and 9, the rotating shaft 61 is driven by the driving means, and the rotating rotor 62 is rotated at a peripheral speed at which particles are not crushed by the properties of the material to be surface treated. The rapid air flow generated by the rotation of the rotary rotor 62 causes a circulating flow around the recycle pipe 63 opened to the impact chamber 68 and returning to the center of the rotary rotor 62.
[0102]
In the apparatus, the powder to be treated supplied from the raw material hopper 64 is subjected to a momentary impact action by a plurality of rotor blades 55 arranged in a rotary rotor 62 that is rotating mainly at a high speed in the impact chamber 68, Furthermore, after colliding with the surrounding stator 58 and receiving an impact action, the particles to be treated are rounded or spheroidized. This state advances as the particles fly and collide. That is, the particles are processed by passing through the 63 recycle pipes a plurality of times with the flow of the air flow generated by the rotation of the rotor blade 55. Further, when the particles are repeatedly hit by the rotor blade 55 and the stator 58, the shape of the particles of the powder to be processed is made spherical.
[0103]
The processed powder that has been spheroidized is collected by the bag filter 22 that passes through the 19 discharge chutes and communicates with the suction blower 24 by opening the discharge valve 59 by the discharge valve control device 28.
[0104]
The processed powder that has been spheroidized is collected by the bag filter 22 that passes through the 19 discharge chutes and communicates with the suction blower 24 by opening the discharge valve 59 by the discharge valve control device 28.
[0105]
It is preferable to rotate the rotating disk so that the peripheral speed of the rotor blade 55 is in the range of 60 m / sec to 150 m / sec.
[0106]
The surface treatment apparatus can be cooled by passing cooling water through the jacket 77, and the treatment temperature can be controlled to some extent.
[0107]
The process of applying a mechanical impact force is particularly preferable when the effect of preventing “retransfer” is further enhanced when the process is performed after the finely pulverizing step of the toner or after the further classification step.
[0108]
Either the classification or the surface treatment may be performed first, but after the classification, the surface treatment is preferably performed in order to prevent fusion in the apparatus due to toner fine powder. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.
[0109]
In the mechanical impact method, it is preferable from the viewpoint of aggregation prevention and productivity to set the treatment temperature to a temperature in the vicinity of the glass transition point Tg of the toner particles (Tg ± 10 ° C.) and to apply the thermomechanical impact. More preferably, it is particularly effective to improve the developing ability and transfer efficiency at a temperature in the range of the glass transition point Tg ± 5 ° C. of the toner.
[0110]
The weight average particle diameter of the toner is 10.0 μm or less, preferably in the range of 3.0 to 8.0 μm. When the weight average particle diameter of the toner is 10.0 μm or less, the effect of preventing “retransfer” is further enhanced. The reason is considered that when the weight average particle diameter of the toner is 10.0 μm or less, the charge amount of the toner on the electrostatic latent image carrier or intermediate transfer body before transfer is further increased.
[0111]
When the weight average particle diameter of the toner is too small, the image density may be lowered due to contamination of the toner carrier.
[0112]
For the weight average particle diameter of the toner of the present invention, Coulter counter TA-II type or Coulter Multisizer (manufactured by Coulter Inc.) is used. As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number distribution of the toner is measured by measuring the volume and number of toners of 2 μm or more using the 100 μm aperture as the aperture. And calculated. Then, the volume-based weight average particle diameter (D4) obtained from the volume distribution according to the present invention was obtained.
[0113]
The present invention is effective when the surface of the electrostatic latent image carrier is mainly composed of a polymer binder. For example, when a protective film mainly composed of a resin is provided on an inorganic electrostatic latent image carrier such as selenium or amorphous silicon, or as a charge transport layer of a function-separated organic image carrier, a charge transport material and a resin are used. In some cases, a protective layer as described above may be provided on the surface layer. As means for imparting releasability to such a surface layer, (1) a resin having a low surface energy is used for the resin constituting the film, and (2) an additive that imparts water repellency and lipophilicity. (3) Adding a material having high releasability in powder form and dispersing. The example of (1) is achieved by introducing a fluorine-containing group or a silicon-containing group into the resin structure. As (2), a surfactant may be used as an additive. Examples of (3) include compounds containing fluorine atoms, that is, fluorine-containing compound powders such as polytetrafluoroethylene, polyvinylidene fluoride, and carbon fluoride. Of these, polytetrafluoroethylene is particularly preferred. In the present invention, it is particularly preferable to disperse the releasable powder such as the fluorine-containing resin (3) in the outermost surface layer.
[0114]
By these means, the contact angle of the surface of the electrostatic latent image carrier with respect to water can be 85 degrees or more (preferably 90 degrees or more). If it is less than 85 degrees, the toner and the toner carrier are likely to deteriorate due to durability.
[0115]
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 image carrier, or an organic image carrier originally composed mainly of a resin In this case, the powder may be dispersed in the uppermost layer without newly providing a surface layer.
[0116]
The addition amount of the powder to the surface layer is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, based on the total mass of the surface layer. When the amount is less than 1% by weight, the effect of improving the durability of the toner and the toner carrier is insufficient. When the amount exceeds 60% by weight, the strength of the film is lowered and the amount of incident light on the image carrier is significantly reduced. Therefore, it is not preferable.
[0117]
The present invention is particularly effective in the case of the direct charging method in which the charging means makes the charging member contact the image carrier. Compared with corona discharge or the like in which the charging means does not come into contact with the image carrier, the load on the surface of the image carrier is large, so that the improvement effect is remarkable in terms of the life of the image carrier, which is one of the preferred applications.
[0118]
One preferred embodiment of the electrostatic latent image carrier used in the present invention will be described below.
[0119]
As a conductive substrate, a cylinder made of a metal such as aluminum or stainless steel; a plastic having a coating layer of an aluminum alloy or an indium oxide-tin oxide alloy; paper or plastic impregnated with conductive particles; or a plastic having a conductive polymer; Cylinder and film are used.
[0120]
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 Alternatively, it is formed of an aluminum oxide material. The film thickness is usually about 0.1 to 10 μm, preferably about 0.1 to 3 μm.
[0121]
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 and amorphous silicon. A charge generating substance such as an inorganic substance is dispersed in a suitable binder and formed by coating or vapor deposition. 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 and vinyl acetate resin. Can be 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 based on the weight of the charge generation material. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.05 to 2 μm.
[0122]
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 a biphenylene, anthracene, pyrene or phenanthrene structure in the main chain or side chain; nitrogen-containing cyclic compounds of indole, carbazole, oxadiazole or pyrazoline; hydrazone compounds; styryl compounds Selenium; selenium-tellurium; amorphous silicon; cadmium sulfide.
[0123]
Examples of binder resins for dispersing these charge transport materials include polycarbonate resins, polyester resins, polymethacrylates, polystyrene resins, acrylic resins, polyamide resins, and organic resins such as poly-N-vinylcarbazole and polyvinylanthracene. A photoconductive polymer is mentioned.
[0124]
A protective layer may be provided as the surface layer. As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or curing agents for these resins are used alone or in combination of two or more.
[0125]
Conductive fine particles may be dispersed in the resin of the 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, antimony. Examples thereof include ultrafine particles of coated tin oxide and zirconium oxide. These may be used alone or in combination of two or more.
[0126]
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 particle size of the conductive and insulating particles is preferably 0.5 μm or less.
[0127]
The content in the protective layer is preferably 2 to 90% by mass, more preferably 5 to 80% by mass with respect to the total mass of the protective layer.
[0128]
The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.
[0129]
The surface layer can be applied by spray coating, beam coating or osmotic coating of the resin dispersion.
[0130]
The contact transfer process applicable to the image forming method of the present invention will be specifically described below.
[0131]
The contact transfer process is to electrostatically transfer the developed image to the transfer material while contacting the transfer means via the transfer material with the electrostatic charge image carrier or intermediate transfer body. The pressure is preferably 2.9 N / m (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.
[0132]
As the 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.⁶-10^TenIt is made of an elastic body of about Ωcm.
[0133]
The present invention is particularly effectively used in an image forming apparatus in which the surface of an electrostatic latent image carrier (photoconductor) 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.
[0134]
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. Alternatively, other monomers or copolymers and blends between the aforementioned binder resins can also be used.
[0135]
The present invention is particularly effectively used for an image forming apparatus having a small diameter 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.
[0136]
In the present invention, it is preferable from the viewpoint of environmental conservation that the charging member is in contact with the photoreceptor so that ozone is not generated.
[0137]
As a preferable process condition when using a charging roller, when a contact pressure of the roller is 5 to 500 g / cm and an AC voltage is superimposed on a DC voltage, AC voltage = 0.5 to 5 kVpp, AC Frequency = 50 to 5 kHz, DC voltage = ± 0.2 to ± 5 kV.
[0138]
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.
[0139]
According to the present invention, as a means for forming a thin toner layer on the toner carrying member in the developing step, a member for regulating the toner layer thickness is used in contact with the toner carrying member by an elastic force, whereby the toner to be developed is used. The charge amount is increased, and this is particularly preferable from the viewpoint of transferability. As the toner layer thickness regulating member that is brought into contact with the elastic force, for example, a member using rubber-like elasticity or the elasticity of a metal leaf spring can be used.
[0140]
The material of the charging roller and charging blade as the contact charging means is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride), and fluorine acrylic resin are applicable.
[0141]
Next, the image forming method of the present invention will be specifically described with reference to the drawings.
[0142]
FIG. 1 shows an image forming apparatus of a type that directly transfers a toner image on an electrostatic latent image carrier onto a transfer material.
[0143]
In FIG. 1, reference numeral 100 denotes a photosensitive drum as an electrostatic latent image carrier, and a primary charging roller 117, a developing device 140, a transfer charging roller 114, a cleaner 116, and a register roller 124 are provided around the photosensitive drum. The photosensitive drum 100 is charged to −700 V by the primary charging roller 117 (applied voltages are AC voltage −2.0 kVpp, DC voltage −700 Vdc). And it exposes by irradiating the photosensitive drum 100 with the laser beam 123 by the laser generator 121, and an electrostatic latent image is formed. The electrostatic latent image on the photosensitive drum 100 is developed with a one-component magnetic toner by the developing device 140 and is transferred onto the transfer material by the transfer roller 114 in contact with the photosensitive drum via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 126 by the conveying belt 125 and fixed on the transfer material. Part of the toner remaining on the electrostatic latent image carrier is cleaned by the cleaning unit 116.
[0144]
As shown in FIG. 2, the developing device 140 is provided with a cylindrical toner carrier 102 (hereinafter referred to as a developing sleeve) made of a non-magnetic metal such as aluminum or stainless steel in the vicinity of the photosensitive drum 100. The gap between 100 and the developing sleeve 102 is maintained at about 300 μm by a sleeve / drum gap holding member (not shown). A stirring bar 141 is disposed in the developing device. A magnet roller 104 is fixed and arranged concentrically with the developing sleeve 102 in the developing sleeve. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in FIG.₁Is development, N₁Is the toner coat amount regulation, S₂Is the toner uptake / conveyance, N₂Affects the prevention of toner blowout. An elastic blade 103 is provided as a member for regulating the amount of magnetic toner that adheres to the developing sleeve 102 and is conveyed, and the amount of toner conveyed to the developing region is controlled by the contact pressure of the elastic blade 103 against the developing sleeve 102. . In the development region, direct current and alternating current development bias is applied between the photosensitive drum 100 and the development sleeve 102, and the toner on the development sleeve flies onto the photosensitive drum 100 in accordance with the electrostatic latent image and becomes a visible image.
[0145]
FIG. 7 shows an image forming apparatus of a type in which a toner image on an electrostatic latent image carrier is primarily transferred onto an intermediate transfer member, and then the toner image on the intermediate transfer member is secondarily transferred onto a recording material.
[0146]
The photosensitive member 1 has a photosensitive layer 1b having an organic optical semiconductor on a substrate 1a, and is rotated by a charging roller 2 (conductive elastic layer 2a, cored bar 2b) that rotates in the direction of an arrow and is opposed and rotated. 1 is charged to a surface potential of about -600V. The exposure is turned on and off according to the digital image information by the polygon mirror, thereby forming an electrostatic charge image having an exposed portion potential of −100V and a dark portion potential of −600V. Using a plurality of developing devices 4-1, 4-2, 4-3 and 4-4, a toner image was obtained by using a reversal development method on magenta toner, cyan toner, yellow toner or black toner on the photoreceptor 1. The toner image is transferred onto the intermediate transfer body 5 (elastic layer 5a, cored bar 5b as a support) for each color, and a four-color superimposed developed image is formed on the intermediate transfer body 5. The transfer residual toner on the photoreceptor 1 is collected in the residual toner container 9 by the cleaner member 8.
[0147]
Since the toner according to the present invention has high transfer efficiency, problems are unlikely to occur even in a system without a simple bias roller or cleaner member.
[0148]
The intermediate transfer member 5 was coated on a pipe-shaped cored bar 5b with an elastic layer 5a in which a carbon black conductive member was sufficiently dispersed in nitrile-butadiene rubber (NBR). The hardness of the coat layer is 30 degrees according to JIS K-6301, and the volume resistivity is 10⁹It was Ω · cm. The transfer current required for transfer from the photosensitive member 1 to the intermediate transfer member 5 is about 5 μA, which was obtained by applying +2000 V to the core metal 5b from the power source. The surface of the intermediate transfer member may be cleaned with the cleaner member 10 after the toner image is transferred from the intermediate transfer member 5 to the transfer material 6.
[0149]
The transfer roller is an elastic material produced by coating a 20 mm metal core 7b with a carbon electroconductivity imparting member sufficiently dispersed in an ethylene-propylene-diene terpolymer (EPDM) foam. The volume resistivity value of the layer 7a is 10⁶An Ω · cm sample having a hardness of 35 degrees based on JIS K-6301 was used. A voltage was applied to the transfer roller to pass a transfer current of 15 μA. As for the contaminated toner on the transfer roller 7 when the toner is collectively transferred from the intermediate transfer member 5 to the transfer material 6, a fur brush cleaner or a cleaning member-less system is generally used as a cleaning member.
[0150]
In the present invention, any one of the developing devices 4-1, 4-2, 4-3 and 4-4 is a magnetic one-component jumping developing system using magnetic toner, and the development as shown in FIG. A vessel configuration was used. The other three developing units for non-magnetic color toner were two-component magnetic brush developing units or non-magnetic one-component developing units.
[0151]
【Example】
Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way. All parts in the following formulations are parts by weight.
[0152]
(Toner Production Example 1)

[0153]
The above materials were mixed in a blender, melt kneaded with a biaxial extruder heated to 130 ° C., the cooled kneaded product was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a jet mill. At this time, the magnetic toner particles are repeatedly pulverized until a predetermined particle size is obtained in the pulverization step as shown in FIG. Subsequently, the finely pulverized product obtained was strictly classified by a multi-division classifier using the Coanda effect to obtain magnetic toner classified particles.
[0154]
The magnetic toner classification particles are applied at 1600 rpm (peripheral speed 80 m / sec) using a surface modification device that applies a mechanical impact force by rotating a rotor using an impact surface treatment device shown in FIGS. ) For 3 minutes to obtain magnetic toner particles. Cooling water at 20 ° C. was passed through the surface reforming apparatus for the purpose of controlling the internal temperature of the apparatus during the surface modification within a preferable range. At this time, the temperature inside the processing apparatus before introducing the magnetic toner classified particles is 30 ° C. After the magnetic toner classified particles are added, the temperature inside the processing apparatus gradually increases, and after 3 minutes, the temperature inside the processing apparatus reaches a maximum of 59. Reached ℃.
[0155]
The content of fine powder of 4 μm or less in the particle size distribution of the classified magnetic toner classified particles was 16 number%, and the content of fine powder of 4 μm or less in the processed magnetic toner particles was 19 number%.
[0156]
Next, 100 parts of the obtained magnetic toner particles were subjected to hydrophobic silica having a primary particle size of 12 nm and hydrophobized with silicone oil and hexamethyldisilazane (treated BET specific surface area of 120 m).²/ G) was added in 1.2 parts and mixed with a mixer to obtain magnetic toner 1. The obtained magnetic toner has a weight average particle diameter of 6.7 μm, 3 μm or more, a particle having a circularity a of 0.90 or more is 96.7% by number, and a particle having a circularity a of 0.98 or more is 23. 2% by number. The standard deviation SD of the circularity distribution in the particles of 3 μm or more was 0.031. Table 1 shows the physical properties of the magnetic toner 1 obtained.
[0157]
(Toner Production Examples 2 to 4)
Magnetic toners 2, 3 and 4 were obtained in the same manner as in Toner Production Example 1 except that the conditions of the surface modification apparatus in Toner Production Example 1 were changed. Table 1 shows the physical properties of the magnetic toners 2, 3 and 4 obtained. The fine powder amounts (number% of 4 μm or less) in the particle size distribution of the magnetic toners 2, 3 and 4 were 21%, 18.5% and 18%, respectively.
[0158]
(Toner Production Example 5)

[0159]
A magnetic toner 5 was obtained in the same manner as in Toner Production Example 1 except that the above materials were used. The obtained magnetic toner has a weight average particle diameter of 6.7 μm, 3 μm or more, 93.8% by number of particles having a circularity a of 0.90 or more, and 22 particles having a circularity a of 0.98 or more. .2% by number. The standard deviation SD of the circularity distribution in the particles of 3 μm or more was 0.036. The internal air temperature during the treatment was a maximum of 60 ° C. due to heat generated by the impact of the rotor and particles. Table 1 shows the physical properties of the magnetic toner 5 obtained.
[0160]
(Toner Production Example 6)
A magnetic toner 6 was obtained in the same manner as in Toner Production Example 1 except that the conditions of the surface modification apparatus in Toner Production Example 1 were changed to 1200 rpm (circumferential speed 60 m / sec) for 1 minute. Table 1 shows the physical properties of the magnetic toner 6 obtained.
[0161]
(Toner Production Example 7)

[0162]
A magnetic toner 7 was obtained in the same manner as in Toner Production Example 1 except that the above materials were used and the condition of the surface modifying apparatus was changed to 1200 rpm (circumferential speed 60 m / sec) for 1 minute. Table 1 shows the physical properties of the magnetic toner 7 obtained.
[0163]
(Toner Production Example 8)

[0164]
The above materials are mixed in a blender, melt kneaded with a biaxial extruder heated to 130 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill. The pulverized product was strictly classified with a multi-division classifier using the Coanda effect to obtain magnetic toner classified particles.
[0165]
Next, 100 parts of the obtained magnetic toner classified particles were subjected to hydrophobized hexamethyldisilazane dry silica having a primary particle size of 16 nm (treated BET specific surface area of 100 m).²/ G) was added in an amount of 0.8 part and mixed with a mixer to obtain magnetic toner 8. Table 1 shows the physical properties of the magnetic toner 8 obtained.
[0166]
(Toner Production Example 9)
A magnetic toner 9 was obtained in the same manner as in Toner Preparation Example 8, except that the toner classified particles obtained in Toner Preparation Example 8 were used to instantaneously pass through 300 ° C. hot air. Table 1 shows the physical properties of the magnetic toner 9 obtained.
[0167]
(Toner Production Example 10)
Using the toner classification particles obtained in Toner Production Example 8, the magnetic properties were changed in the same manner as in Toner Production Example 1 except that the condition of the surface modifying device was changed to 1200 rpm (circumferential speed 60 m / sec) for 1 minute. Toner 10 was obtained. The physical properties of the obtained magnetic toner 10 are shown in Table 1.
[0168]
(Toner Production Example 11)

[0169]
A magnetic toner 11 was obtained in the same manner as in Toner Production Example 1 except that the above materials were used. The obtained magnetic toner has a weight average particle diameter of 6.9 μm, 3 μm or more, a particle having a circularity a of 0.90 or more is 96.3% by number, and a particle having a circularity a of 0.98 or more is 32. 0.0% by number. The standard deviation SD of the circularity distribution in the particles of 3 μm or more was 0.036. The internal air temperature during the treatment was 73 ° C. maximum due to heat generated by the impact of the rotor and particles. The physical properties of the obtained magnetic toner 11 are shown in Table 1.
[0170]
In addition, the processing apparatus cooling water temperature at the time of a process was 30 degreeC.
[0171]
(Toner Production Example 12)

[0172]
A magnetic toner 12 was obtained in the same manner as in Toner Production Example 1 except that the above materials were used. The obtained magnetic toner has a weight average particle diameter of 6.5 μm, 3 μm or more, 90.2% by number of particles having a circularity a of 0.90 or more, and 8 particles having a circularity a of 0.98 or more. 0.5% by number. The standard deviation SD of the circularity distribution in particles of 3 μm or more was 0.047. The internal air temperature during the treatment was a maximum of 45 ° C. due to heat generated by the impact of the rotor and particles. Table 1 shows the physical properties of the magnetic toner 12 obtained.
[0173]
The content of fine powder of 4 μm or less in the particle size distribution of the magnetic toner classified particles after classification of the magnetic toner 12 is 15% by number, and the content of fine powder of 4 μm or less in the processed magnetic toner particles is 26% by number. Met.
[0174]
(Toner Production Example 13)

[0175]
A magnetic toner 13 was obtained in the same manner as in Toner Production Example 1 except that the above materials were used. The obtained magnetic toner has a weight average particle diameter of 6.4 μm, 3 μm or more, a particle having a circularity a of 0.90 or more is 87.0% by number, and a particle having a circularity a of 0.98 or more is 4%. 0.5% by number. The standard deviation SD of the circularity distribution in the particles of 3 μm or more was 0.046. The internal air temperature during the treatment was a maximum of 37 ° C. due to heat generated by the impact of the rotor and particles. Table 1 shows the physical properties of the magnetic toner 13 obtained.
[0176]
The content of fine powder of 4 μm or less in the particle size distribution of the magnetic toner classified particles after classification of the magnetic toner 13 is 14% by number, and the content of fine powder of 4 μm or less in the processed magnetic toner particles is 27 numbers. %Met.
[0177]
[Table 1]

[0178]
(Photoreceptor Production Example 1)
As the photoreceptor, an Al cylinder having a diameter of 30 mm was used as a base. To this, layers having a structure as shown in FIG. 3 were sequentially laminated by dip coating to produce a photoreceptor.
[0179]
(1) Conductive coating layer: mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenol resin. Film thickness 15 μm.
[0180]
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
[0181]
(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.
[0182]
(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 by the Oswald viscosity method) at a weight ratio of 8:10, and polytetrafluoroethylene powder ( 10% by weight of the total solid content was added and dispersed uniformly. Film thickness 15 μm. The contact angle with water was 95 degrees.
[0183]
The contact angle was measured using pure water, and the device used was Kyowa Interface Science Co., Ltd., contact angle meter CA-X type.
[0184]
(Photoreceptor Production Example 2)
In the photoreceptor production example 1, a photoreceptor was prepared in the same manner without adding polytetrafluoroethylene powder. The contact angle with water was 74 degrees.
[0185]
(Photoreceptor Production Example 3)
The photoreceptor was produced according to the photoreceptor production example 1 up to the charge generation layer. As the charge transport layer, a hole transporting triphenylamine compound dissolved in a polycarbonate resin at a mass ratio of 10:10 was used. Film thickness 20 μm. Furthermore, as a protective layer, 30% of polytetrafluoroethylene powder (particle size 0.2 μm) is added to a composition in which the same material is dissolved at a weight ratio of 5:10 to the total solid content. The material dispersed in was spray-coated on the charge transport layer. Film thickness 5 μm. The contact angle with water was 102 degrees.
[0186]
Example 1
As the image forming apparatus, an apparatus generally shown in FIGS. 1 and 2 was used.
[0187]
Using an organic photoreceptor (OPC) drum of Production Example 3 as an electrostatic latent image carrier, dark portion potential V_d= -650V, Bright part potential V_L= -210V. The gap between the photosensitive drum and the developing sleeve is set to 300 μm, and a urethane rubber blade having a thickness of 1.0 mm and a free length of 10 mm is applied to the toner carrier as a toner regulating member at a linear pressure of 14.7 N / m (15 g / cm). Touched.
[0188]
Next, a DC bias component V as a developing bias_dc= -500V, superimposed AC bias component V_PP= 1500 V, f = 2000 Hz was used.
[0189]
Transfer roller as shown in FIG. 4 (made of ethylene-propylene rubber in which conductive carbon is dispersed, volume resistance value 10 of conductive elastic layer)⁸Ωcm, surface rubber hardness 24 °, diameter 20 mm, contact pressure 49 N / m (50 g / cm) is constant with respect to the photosensitive member peripheral speed (48 mm / sec), and the transfer bias is swung between 2 to 20 μA. The transcription latitude was evaluated. The magnetic toner 1 was used as the toner, and the image was printed in an environment of 32.5 ° C. and 80% RH. 75g / m for transfer paper²Paper was used.
[0190]
At this time, the range in which the transfer efficiency from the photoconductor to the transfer material is 90% or more shows a high transfer efficiency in a wide range of 4 to 18 μA, and there is no omission of transfer of characters and lines, and the image is scattered on the image. No good image was obtained.
[0191]
The above transfer efficiency was obtained by printing a solid black part of 5 mm square on three places on the center and both ends of the transfer material, stopping while the transfer material passed through the image forming apparatus before going to the fixing device, and obtained by the following method. This is the average value of three locations of transfer efficiency.
[0192]
The transfer efficiency is determined by tapering off the transfer residual toner after transfer on the photoconductor with a Mylar tape and pasting it on the paper, the Macbeth density (a), and the Mylar tape on the toner image transferred onto the transfer paper. The numerical values obtained by subtracting the Macbeth density (c) of the tape only on the paper from the Macbeth density (b) of the pasted material are the transfer residual density (A) and the density (B) of the transferred image as follows. Calculated by the formula.
[0193]
Transfer residual density (A) = density (a) -density (c)
Transfer image density (B) = density (b) -density (c)
Transfer efficiency (%) = {[transfer image density (B)] / [transfer residual density (A) + transfer image density (B)]} × 100
[0194]
Furthermore, when 6000 sheets were continuously drawn and the amount of photoconductor scraping was measured with a film thickness meter, the amount of scraping was very small, 0 to 1 μm.
[0195]
Example 2
Images were produced under the same apparatus and conditions as in Example 1 except that toner 2 was used as the toner and the OPC drum of photoreceptor production example 1 was used as the electrostatic latent image carrier. At this time, the transfer efficiency from the photoconductor to the transfer material is 90% or more, and the transfer efficiency is high in a wide range of 4 to 17 [mu] A. No good image was obtained.
[0196]
Example 3
Images were produced under the same apparatus and conditions as in Example 1 except that toner 3 was used as the toner and the OPC drum of photoreceptor production example 1 was used as the electrostatic latent image carrier. At this time, the transfer efficiency from the photoconductor to the transfer material is 90% or more, and the transfer efficiency is high in a wide range of 4 to 16 .mu.A. No good image was obtained.
[0197]
Example 4
Images were produced under the same apparatus and conditions as in Example 1 except that toner 4 was used as the toner and the OPC drum of photoreceptor production example 1 was used as the electrostatic latent image carrier. At this time, the transfer efficiency from the photoconductor to the transfer material is 90% or more, and the transfer efficiency is high under a wide range of 4 to 14 μA. No good image was obtained.
[0198]
Example 5
Using toner 5, the image was printed out with the same apparatus and conditions as in Example 3. At this time, the range in which the transfer efficiency from the photosensitive member to the transfer material of 90% or more was 2 to 10 μA, which was slightly worse than Example 1, but there was no problem in practical use, and there was no omission in transferring characters and lines. As a result, a good image without scattering on the image was obtained.
[0199]
Example 6
The toner 6 was used, and the image was printed using the same apparatus and conditions as in Example 3. The range in which the transfer efficiency from the photoconductor to the transfer material of 90% or more can be obtained is 2 to 8 μA, which is slightly worse than that of Example 1, and a slight void is seen in the line image portion, but this is a particular problem in practical use. There was no, and a good image without scattering on the image was obtained.
[0200]
Reference example 1
The toner 7 was used, and the image was printed using the same apparatus and conditions as in Example 3. The range in which the transfer efficiency from the photosensitive member to the transfer material of 90% or more at this time is 2 to 8 μA, which is slightly worse than that of Example 1 and is slightly scattered on the image. A good image was obtained.
[0201]
Reference example 2
Except that the toner 12 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, the transfer efficiency of 90% or more from the photoconductor to the transfer material is 2 to 6 μA, which is slightly worse than that of Example 1, and a good image with no practical problems although some scattering was seen on the image. was gotten.
[0202]
Comparative Example 1
Except that the toner 8 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, there was no range where 90% or more transfer efficiency from the photoconductor to the transfer material was obtained, and the toner utilization efficiency was low. Further, the image was slightly noticeable in the transfer of characters and lines.
[0203]
Comparative Example 2
Images were produced using the same apparatus and conditions as in Comparative Example 1 except that the toner 9 was used and the OPC drum of Photoconductor Production Example 2 was used as the electrostatic latent image carrier. As a result, the transfer efficiency from the photoconductor to the transfer material can be 90% or more is only 8 μA, sufficient transfer latitude cannot be obtained, and the image density is thin and poor, and the image is very scattered. there were. Furthermore, defective photoconductor cleaning occurred after printing 500 sheets.
[0204]
Comparative Example 3
Images were produced using the same apparatus and conditions as in Comparative Example 1 except that the toner 10 was used and the OPC drum of Photoconductor Production Example 2 was used as the electrostatic latent image carrier. As a result, the transfer efficiency from the photoconductor to the transfer material can be 90% or more is only 6 μA, sufficient transfer latitude cannot be obtained, and the image density is thin and poor, and the image is very scattered. there were.
[0205]
Comparative Example 4
Except that the toner 9 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, the transfer efficiency from the photoconductor to the transfer material can be 90% or more is only 8 μA, a sufficient transfer latitude cannot be obtained, and the image density is low, and the temperature is 15 ° C. and 10%. A cleaning failure occurred when 300 images were printed.
[0206]
Comparative Example 5
Except that the toner 10 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, the transfer efficiency of 90% or more from the photoconductor to the transfer material is only 6 μA, sufficient transfer latitude cannot be obtained, and the image density is low, and the scattering, resolution, and void are inferior. It became a thing.
[0207]
Comparative Example 6
Except that the toner 11 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, the range in which the transfer efficiency from the photosensitive member to the transfer material of 90% or more was as narrow as 8 to 9 μA, and the image density was low, and the scattering, resolving power, and void were inferior.
[0208]
Comparative Example 7
Except that the toner 13 was used, the image was printed using the same apparatus and conditions as in Example 2. As a result, the transfer efficiency of 90% or more from the photoconductor to the transfer material is only 6 μA, sufficient transfer latitude cannot be obtained, and the image density is low, and the scattering, resolution, and void are inferior. It became a thing.
[0209]
Example 7
As the image forming apparatus, an apparatus generally shown in FIGS. 1 and 2 was used.
[0210]
Using an organic photoreceptor (OPC) drum of Production Example 3 as an electrostatic latent image carrier, dark portion potential V_d= -550V, bright part potential V_L= −250V. The clearance between the photosensitive drum and the developing sleeve is 300 μm, and the toner carrier has a layer thickness of about 7 μm and a JIS center line average roughness (Ra) of 1.4 μm, and the surface is blasted with a diameter of 20 φ. Using a developing sleeve formed on an aluminum cylinder, a developing magnetic pole of 95 mT (950 gauss), a toner regulating member having a thickness of 1.0 mm and a free length 10 mm urethane rubber blade of 14.7 N / m (15 g / cm) The contact was made by pressure.
[0211]
100 parts of phenolic resin
90 parts of graphite (particle size approx. 7μm)
10 parts of carbon black
[0212]
Next, a DC bias component V as a developing bias_dc= -400V, superimposed AC bias component V_PP= 1500 V, f = 2000 Hz, development contrast (V_L-V_dc) Reversal development was performed at 150V.
[0213]
Transfer roller as shown in FIG. 4 (made of ethylene-propylene rubber in which conductive carbon is dispersed, volume resistance value 10 of conductive elastic layer)⁸Printing was performed with Ωcm, surface rubber hardness of 24 °, diameter of 20 mm, and contact pressure of 49 N / m (50 g / cm) at a constant speed relative to the peripheral speed of the photoreceptor (48 mm / sec).
[0214]
Using magnetic toner 1 as a toner, and continuously printing 7000 sheets in an environment of 15 ° C. and 10% RH, a sufficient solid image density was maintained as shown in Table 2, and a ghost, A good image with high resolving power without scattering and voids was obtained.
[0215]
In this embodiment, the evaluation of splattering is a splattering evaluation with fine fine lines related to the image quality of a graphical image, and is a splattering evaluation with a 100 μm width line that is more likely to scatter than characters and lines.
[0216]
The resolving power was evaluated based on the reproducibility of small dots (X = 50 μmφ) isolated dots as shown in FIG.
[0217]
The evaluation of hollowing out is based on thick paper (approximately 128 g / cm²) Is the evaluation when printed.
[0218]
Furthermore, the transfer bias was evaluated by shaking the transfer bias between 2 and 20 μA in an environment of 32.5 ° C. and 80% RH. 75g / cm for transfer paper²Paper was used. At this time, the range in which the transfer efficiency from the photoconductor to the transfer material is 90% or more shows a high transfer efficiency in a wide range of 4 to 18 μA, and there is no skipping of characters and lines, and no scattering on the image. A good image was obtained.
[0219]
The transfer efficiency described above was used for the transfer efficiency.
[0220]
Furthermore, when 6000 sheets were continuously printed and the amount of photoconductor scraping was measured with a film thickness meter, the amount of scraping was very small at 0.5 μm.
[0221]
Example 8
Example except that toner 2 is used as the toner and the OPC drum of photoreceptor production example 1 is used as the electrostatic latent image carrier.7The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0222]
Example 9
Using toner 3 as the toner, using the OPC drum of photoreceptor production example 1 as the electrostatic latent image carrier, dark portion potential V_d= -550V, bright part potential V_L= -170V, development contrast (V_L-V_dc) Example except that = 230V7The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0223]
Example 10
Example except that toner 4 was used as the toner and the OPC drum of photoreceptor production example 1 was used as the electrostatic latent image carrier.9The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0224]
Example 11
Using toner 5 and using the OPC drum of photoreceptor production example 1 as an electrostatic latent image carrier, dark portion potential V_d= -400V, bright part potential V_L= -100V, DC bias component V as development bias_dc= -300V, superimposed AC bias component V_PP= 1600V, f = 1800Hz, development contrast (V_L-V_dc) = Example except that it is 200V9The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0225]
Example 12
Example using toner 69The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0226]
Reference example 3
Example using toner 79The image was printed using the same equipment and conditions as in. As a result, good results were obtained as shown in Table 2.
[0227]
Reference example 4
Example using toner 129The image was printed using the same equipment and conditions as in. As a result, as shown in Table 2, a good image having no practical problem was obtained.
[0228]
Comparative Example 8
Example except that toner 8 is used8The image was printed using the same equipment and conditions as in. As a result, there was no range where 90% or more transfer efficiency from the photoconductor to the transfer material was obtained, and the toner utilization efficiency was low. Further, the image was slightly noticeable in the transfer of characters and lines.
[0229]
Comparative Example 9
Images were produced using the same apparatus and conditions as in Comparative Example 8 except that the toner 9 was used and the OPC drum of Photoconductor Production Example 2 was used as the electrostatic latent image carrier. As a result, the transfer efficiency from the photoconductor to the transfer material can be 90% or more is only 8 μA, sufficient transfer latitude cannot be obtained, and the image density is thin and poor, and the image is very scattered. there were. Furthermore, defective photoconductor cleaning occurred after printing 500 sheets.
[0230]
Comparative Example 10
Images were produced under the same apparatus and conditions as in Comparative Example 8 except that the toner 10 was used and the OPC drum of Photosensitive Member Production Example 2 was used as the electrostatic latent image carrier. As a result, the transfer efficiency from the photoconductor to the transfer material can be 90% or more is only 6 μA, sufficient transfer latitude cannot be obtained, and the image density is thin and poor, and the image is very scattered. there were.
[0231]
Comparative Example 11
Example except that toner 9 is used8The image was printed using the same equipment and conditions as in. As a result, as shown in Table 2, in the durability evaluation under low temperature and low humidity, cleaning failure occurred at 1000 sheets. Also, the transfer latitude was narrow.
[0232]
Comparative Example 12
Example except that toner 10 is used8The image was printed using the same equipment and conditions as in. As a result, as shown in Table 2, the image density was low, and the scattering, resolving power, and void were inferior. Also, the transfer latitude was narrow.
[0233]
Comparative Example 13
Example except that toner 11 is used8The image was printed using the same equipment and conditions as in. As a result, as shown in Table 2, the image density was low, and the scattering, resolving power, and void were inferior.
[0234]
Comparative Example 14
Example except that toner 13 is used8The image was printed using the same equipment and conditions as in. As a result, as shown in Table 2, the image density was low, and the scattering, resolving power, and void were inferior. Also, the transfer latitude was narrow.
[0235]
[Table 2]

[0236]
* 1 In the evaluation of scattering, A is very good, B is good, and C is scattered.
* 2 In the evaluation of resolving power, A is very good, B is good, and C is insufficient.
* 3 In the evaluation of hollows, A is very good, B is good, and C is hollow.
[0237]
Example 13
As the image forming apparatus, an apparatus generally shown in FIG. 7 was used.
[0238]
As the color toner, cyan toner, magenta toner, and yellow toner for Canon LBP-2030 were used, and each was developed using a non-magnetic one-component developer.
[0239]
As the photoconductor, the photoconductor production example 1 was used.
[0240]
As the magnetic toner, toner 2 was used.
[0241]
The transfer current range of 90% or more of the color toner three-color image was 12 to 20 μA. Further, the transfer current range of the monochromatic magnetic toner 2 image was 4 to 18 μA.
[0242]
With the magnetic toner having the above-described configuration, a satisfactory image having no problem was obtained at a transfer current value of 15 μA in a four-color full-color image.
[0243]
Comparative Example 15
Example13In the same manner as described above, only the magnetic toner was changed to 10 for evaluation. In a four-color full-color image, only the black toner was lost, the resolution was inferior, and the transferability was poor.
[0244]
【The invention's effect】
According to the present invention, the toner has one or more endothermic peaks in differential thermal analysis at 120 ° C. or less, and in the toner having a particle diameter of 3 μm or more, 90% by number or more of toners having a circularity a of 0.90 or more. Re-transfer using toner having a circularity a of 0.98 or more and less than 30% by number while maintaining high image density and latent image reproducibility. A high-quality and sharp image can be obtained.
[0245]
In particular, a wide transfer latitude can be obtained as compared with the conventional magnetic toner.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an image forming apparatus suitable for the present invention.
FIG. 2 is a schematic diagram illustrating an example of a developing unit for one-component development.
FIG. 3 is a schematic view showing an example of the configuration of a photoreceptor used in the present invention.
FIG. 4 is a schematic diagram illustrating an example of a contact transfer unit.
FIG. 5 is a diagram illustrating an example of a toner pulverization process suitable for obtaining the toner of the present invention.
FIG. 6 is a diagram illustrating an example of an isolated dot pattern used for resolution evaluation.
FIG. 7 is a schematic view showing an example of another image forming apparatus suitable for the present invention.
FIG. 8 is an explanatory diagram illustrating an example of a processing system for controlling the circularity of toner.
FIG. 9 is an explanatory view showing an impact surface treatment apparatus in the system of FIG. 8;
[Explanation of symbols]
100 photoconductor (electrostatic latent image carrier)
102 Developing sleeve (toner carrier)
103 Contact blade
104 Magnet roller
114 Transfer charging roller
116 Cleaner
117 Primary charging roller
140 Developer
141 Stir bar

Claims (37)

In an electrostatic charge image developing toner having at least a toner particle containing a binder resin and a colorant, and an inorganic fine powder,
The toner has one or more endothermic peaks in a differential thermal analysis in the temperature range of 60 ° C. to 120 ° C. , and the toner has a circularity a calculated by the following formula of 0 for particles having a particle diameter of 3 μm or more. 90 or more particles of 90 or more, and less than 30% of particles having a circularity a of 0.98 or more ,

(Where L ₀ represents the circumference of a circle having the same projected area as the particle image,
L represents the perimeter of the projected image of the particle. )
The toner has a standard deviation SD of a circularity distribution obtained from the following formula of particles having a particle diameter of 3 μm or more of 0.045 or less,

The toner has a weight average particle diameter of 8.0 μm or less,
The toner for developing an electrostatic charge image , wherein the toner is subjected to a spheroidizing treatment that applies at least a mechanical impact force in a toner production process having at least a melting / kneading process and a pulverizing process . 2. The electrostatic image developing toner according to claim 1 , wherein the toner has a particle size of 3 [mu] m or more and a standard deviation SD of circularity distribution is 0.040 or less. 3. The electrostatic image developing toner according to claim 1, wherein the toner has 93% by number or more of particles having a particle size of 3 μm or more and a circularity a of 0.90 or more. The toner is the electrostatic image developing toner according to any one of claims 1 to 3, characterized in that it has endothermic peaks at one or more 70 ° C. or more regions in the differential thermal analysis. The toner according to any one of claims 1 to 4 endothermic peak and having 110 ° C. 1 or more below in differential thermal analysis of the toner. The toner is 100 parts by weight of the binder resin, electrostatic charge image development according to any one of claims 1 to 5, characterized in that it has a magnetic toner particles containing a magnetic material 30 to 200 parts by weight Toner. 2. The toner binder resin according to claim 1, wherein a molecular weight peak is in a range exceeding a molecular weight of 15,000 in a molecular weight distribution measured by GPC, and a content of a component having a molecular weight of 10,000 or less is 25% or less. The toner for developing an electrostatic charge image according to any one of items 1 to 6 . 8. The electrostatic image developing toner according to claim 7 , wherein the binder resin of the toner does not have a peak or a shoulder in a region having a molecular weight of 15000 or less. Charging the electrostatic latent image carrier;
Forming an electrostatic latent image on the charged electrostatic latent image carrier;
A step of developing the electrostatic latent image with toner carried on the toner carrying member to form a toner image on the electrostatic latent image carrying member; and a transfer member to which a voltage is applied. A step of transferring the toner image on the electrostatic latent image carrier onto a transfer material in contact with the toner;
In an image forming method having
The toner has at least toner particles containing at least a binder resin and a colorant, and inorganic fine powder,
The toner has one or more endothermic peaks in differential thermal analysis in a temperature range of 60 ° C. to 120 ° C. ,
The toner is in a particle diameter 3μm or more particles, circularity a, which is obtained by the following formula has a 0.90 or more particles 90% by number or more and 30 the number of circularity a of 0.98 or more particles has less than%,

(Where L ₀ represents the circumference of a circle having the same projected area as the particle image,
L represents the perimeter of the projected image of the particle. )
The toner has a standard deviation SD of a circularity distribution obtained from the following formula of particles having a particle diameter of 3 μm or more of 0.045 or less,

The toner has a weight average particle diameter of 8.0 μm or less,
An image forming method , wherein the toner is subjected to a spheroidizing process that applies at least a mechanical impact force in a toner manufacturing process having at least a melting / kneading process and a pulverizing process . The image forming method according to claim 9 , wherein the toner has a particle size of 3 μm or more and a standard deviation SD of the circularity distribution is 0.040 or less. 11. The image forming method according to claim 9, wherein the toner has 93% by number or more of particles having a particle size of 3 μm or more and a circularity a of 0.90 or more. The image forming method according to claim 9, wherein the toner has at least one endothermic peak in a differential thermal analysis in a region of 70 ° C. or higher. The image forming method according to claim 9, wherein the toner has one or more endothermic peaks in a differential thermal analysis at 110 ° C. or lower. The toner is 100 parts by weight of the binder resin, the image forming method according to any one of claims 9 to 13, characterized in that it has a magnetic toner particles containing a magnetic material 30 to 200 parts by weight. The toner image forming method according to any one of claims 9 to 14, in the manufacturing process of the toner, characterized in that the spheronization process of adding at least mechanical impact force is applied. The binder resin of the toner, claim in molecular weight distribution measured by GPC, and the range of molecular weight peaks of more than 15000, and a molecular weight of 10,000 or less of component content of is equal to or less than 25% 9 16. The image forming method according to any one of items 15 to 15 . The image forming method according to claim 16 , wherein the binder resin of the toner does not have a peak or a shoulder in a region having a molecular weight of 15000 or less. Using a toner layer thickness regulating member abuts an elastic force on the toner carrying member, an image forming method according to any one of claims 9 to 17, wherein the forming a layer of toner on the toner carrying member. The image forming method according to any one of claims 9 to 18 contact angle for water of the surface of the latent electrostatic image bearing member is equal to or not less than 85 degrees. The image forming method according to claim 19 , wherein the latent electrostatic image bearing member contains a substance containing fluorine on a surface thereof. 21. The image forming method according to claim 20 , wherein the substance containing fluorine is a fine powder containing fluorine. The image forming method according to any one of claims 9 to 21 potential contrast of the electrostatic latent image is equal to or less than 400V. Charging the electrostatic latent image carrier;
Forming an electrostatic latent image on the charged electrostatic latent image carrier;
Developing the electrostatic latent image with toner carried on the toner carrier to form a toner image on the electrostatic latent image carrier;
A step of primary transfer of the toner image on the electrostatic latent image carrier to the intermediate transfer member; and a transfer member to which a voltage is applied is brought into contact with the recording material, so that the toner image on the intermediate transfer member is transferred to the recording material. Secondary transfer to
In an image forming method having
The toner has at least toner particles containing at least a binder resin and a colorant, and inorganic fine powder,
The toner has one or more endothermic peaks in a differential thermal analysis in the temperature range of 60 ° C. to 120 ° C. , and the toner has a circularity a of 0. 90 or more particles of 90 or more and 90% or less of particles having a circularity a of 0.98 or more ,

(Where L ₀ represents the circumference of a circle having the same projected area as the particle image,
L represents the perimeter of the projected image of the particle. )
The toner has a standard deviation SD of a circularity distribution obtained from the following formula of particles having a particle diameter of 3 μm or more of 0.045 or less,

The toner has a weight average particle diameter of 8.0 μm or less,
An image forming method , wherein the toner is subjected to a spheroidizing process that applies at least a mechanical impact force in a toner manufacturing process having at least a melting / kneading process and a pulverizing process . 24. The image forming method according to claim 23 , wherein the toner has a particle size of 3 [mu] m or more and a standard deviation SD of circularity distribution is 0.040 or less. 25. The image forming method according to claim 23, wherein the toner has 93% by number or more of particles having a particle size of 3 μm or more and a circularity a of 0.90 or more. The image forming method according to any one of claims 23 to 25, wherein the toner has one or more endothermic peaks in a differential thermal analysis in a region of 70 ° C or higher. 27. The image forming method according to claim 23, wherein the toner has one or more endothermic peaks in a differential thermal analysis at 110 ° C. or lower. The toner is 100 parts by weight of the binder resin, the image forming method according to any one of claims 23 to 27, characterized in that a magnetic toner containing a magnetic material 30 to 200 parts by weight. The toner binder resin has a molecular weight peak in a range exceeding a molecular weight of 15,000 in a molecular weight distribution measured by GPC, and a content of a component having a molecular weight of 10,000 or less is 25% or less. 28. The image forming method according to any one of 23 to 27 . 30. The image forming method according to claim 29 , wherein the binder resin of the toner does not have a peak or a shoulder in a region having a molecular weight of 15000 or less. Using a toner layer thickness regulating member abuts an elastic force on the toner carrying member, an image forming method according to any one of claims 23 to 30, characterized in that to form a layer of toner on the toner carrying member. The image forming method according to any one of claims 23 to 31 the electrostatic latent image is characterized in that it is a digital latent image. The image forming method according to any one of claims 23 to 32 contact angle for water of the surface of the latent electrostatic image bearing member is equal to or not less than 85 degrees. 34. The image forming method according to claim 33 , wherein the electrostatic latent image carrier contains a substance containing fluorine on a surface thereof. 35. The image forming method according to claim 34 , wherein the substance containing fluorine is a fine powder containing fluorine. The image forming method according to any one of claims 23 to 35 potential contrast of the electrostatic latent image is equal to or less than 400V. The toner is a magnetic toner having magnetic toner particles containing a magnetic material as a colorant;
A color toner that is primarily transferred onto the intermediate transfer member using the magnetic toner together with at least one color toner selected from the group consisting of a non-magnetic cyan toner, a non-magnetic yellow toner, and a non-magnetic magenta toner. image secondarily transferred collectively to the recording material, the magnetic toner and image forming method according to any one of claims 23 to 36, characterized in that to obtain a color toner image having the non-magnetic color toner.

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