JP4040420B2 - Image forming method and toner - Google Patents

Description

【００９８】
上式において、粒子投影像の周囲長とは、二値化された粒子像のエッジ点を結んで得られる輪郭線の長さであり、相当円の周囲長とは、二値化された粒子像と同じ面積を有する円の外周の長さである。円相当径とは、測定された粒子の２次元画像の面積と同面積を有する円の直径である。
【００９９】
フロー式粒子像測定装置としてＦＰＩＡ−１０００（東亜医用電子社製）を用いる。
【０１００】
測定方法としてはイオン交換水に界面活性剤（好ましくは和光純薬製コンタミノン）を０．１〜０．５質量％加えて調整した溶液１０ｍｌ（２０℃）に測定試料を０．０２ｇ加えて均一に分散させて試料分散液を調製した。
【０１０１】
分散させる手段としてはエスエムテー社製の超音波分散機ＵＭ−５０（振動子は５φのチタン合金チップ）を用い、分散時間は５分とし、その際、分散媒の温度が４０℃以上にならないように冷却した。測定は０．６０〜４００μｍの範囲を２２６チャンネルに分割し、実際の測定では円相当径が０．６０μｍ以上１５９．２１μｍ未満の範囲で粒子の測定を行う。
【０１０２】
本発明のトナーのフロー式粒子像測定装置で計測される個数基準の円相当径−円形度スキャッタグラムにおける円形度の標準偏差は、０．０１０〜０．０４０であることが好ましく、０．０１５〜０．０３５であることがより好ましい。
【０１０３】
本発明のトナーの円形度の標準偏差が０．０４０を超える場合には、トナーの形状分布が拡がるために、均一転写性が悪化し、ベタ画像の濃度むらを起こしやすい。またクリーナーレスシステムでは転写残トナー増による帯電不良を引き起こしやすい。
【０１０４】
本発明のトナーの円形度の標準偏差が０．０１０未満の場合には製造面において、再現性、収率が著しく悪化し、コストアップにつながるばかりでなく、感光体や転写ベルト等のトナーのクリーニング性が不十分となりやすい。
【０１０５】
本発明のトナーは、上記のように球形に近いことが良いといった観点から、原材料を混合し混練・粉砕して得られる粉砕トナーをターボミル等で機械的に粉砕して得られる粉砕トナーもしくは、重合性単量体、着色剤、離型剤及び重合開始剤から成る単量体組成物を水系媒体中で懸濁重合して得られる重合トナーであることが好ましい。特に、円形度の高さくる転写性・現像性といった点を考慮すると、重合トナーの方が好ましい。
【０１０６】
本発明のトナーは、ネガ帯電トナーにも、ポジ帯電トナーにも適用し得るが、シリカのネガ帯電性を考慮すると、ネガトナーの方が本発明を良好に発現し得る。
【０１０７】
本発明のシリカ微粉体（Ａ）、（Ｂ）は、高湿環境下での疎水性を維持するために、疎水化処理されていることが好ましい。特に、シランカップリング剤またはシリコーンオイルにより処理されていることがより好ましい。
【０１０８】
また、均一帯電性といった観点からは、シリカ微粉体（Ａ）及び（Ｂ）に用いられる処理剤は、同一の処理剤を用いた方が好ましい。つまり、シリカ微粉体（Ａ）及び（Ｂ）両者ともシランカップリング剤で処理するかシリコーンオイルで処理するかのいずれかが好ましい。
【０１０９】
シランカップリング剤は、カップリング処理を施す以前のシリカ１００質量部に対して、１〜４０質量部、好ましくは２〜３５質量部を用いるのが良い。１乃至４０質量部であると耐湿性が向上し凝集体が発生しにくい。
【０１１０】
本発明に用いられるシランカップリング剤としては、下記一般式で示されるものが挙げられる。
【０１１１】
ＲｍＳｉＹｎ
〔式中、Ｒはアルコキシ基又は塩素原子を示し、ｍは１〜３の整数であり、Ｙは、炭化水素基（例えば、アルキル基、ビニル基、グリシドキシ基，メタクリル基が挙げられる）を示し、ｎは３〜１の整数である〕。
【０１１２】
例えば、ジメチルジクロルシラン，トリメチルクロルシラン，アリルジメチルクロルシラン，ヘキサメチルジシラザン，アリルフェニルジクロルシラン，ベンジルジメチルクロルシラン，ビニルトリエトキシシラン、γ−メタクリルオキシプロピルトリメキシシラン，ビニルトリアセトキシシラン，ジビニルクロルシラン，ジメチルビニルクロルシラン等をあげることができる。中でも、ヘキサメチルジシラザンが良好に疎水性を上げ、トナーの環境による帯電性差を抑制する観点で好ましい。
【０１１３】
上記シリカのシランカップリング剤処理は、シリカを撹拌によりクラウド状としたものに気化したシランカップリング剤を反応させる乾式処理又は、ケイ酸微粉体を溶媒中に分散させシランカップリング剤を滴下反応させる湿式法の如き一般に知られた方法で処理することができる。
【０１１４】
シリカは、珪素ハロゲン化合物の蒸気相酸化（例えば酸素・水素火陥中の熱分解酸化反応）による乾式法や、珪酸ナトリウム，アルカリ土類金属珪酸塩、珪酸塩等の、酸、アンモニア、塩類、アルカリ塩類による分解を用いる湿式法により得られるシリカが用いられる。特に、本発明の好ましいシリカとしては、乾式方により生成したものであり、結晶型としてはアモルファスのものが好ましい用いられる。
【０１１５】
シリカの表面処理を施すシリコーンオイルとしては、一般に次の式により示されるのが好ましい。
【０１１６】
【化１】

〔式中、Ｒ₁〜Ｒ₁₀は、同一でも異なっていてもよく、水素、水酸基、アルキル基、ハロゲン、フェニル基、置換基を有するフェニル基、脂肪酸基、ポリオキシアルキレン基又はパーフルオロアルキル基を示し、ｍ及びｎは整数を示す〕。
【０１１７】
好ましいシリコーンオイルとしては、２５℃における粘度が５〜２００ｍｍ²／ｓのものが好ましく用いられ、４０〜８０ｍｍ²／ｓが均一に処理する観点では、より好ましく用いられる。分子量が低すぎて低粘度のシリコーンオイルは加熱処理により、揮発分が発生することがあり好ましくなく、一方、分子量が高すぎて高粘度のシリコーンオイルは表面処理操作がしにくくなる。シリコーンオイルとしては、メチルシリコーンオイル，ジメチルシリコーンオイル，フェニルメチルシリコーンオイル，クロルフェニルメチルシリコーンオイル，アルキル変性シリコーンオイル，脂肪酸変性シリコーンオイル，ポリオキシアルキル変性シリコーンオイルが好ましい。
【０１１８】
ポジトナーに適用する場合、シリコーンオイルとして、側鎖に窒素原子を少なくとも１つ以上有するオルガノ基を有する変性シリコーンオイルでも良い。例えば少なくとも下記式で表わされる部分構造を具備する変性シリコーンオイルが挙げられる。
【０１１９】
【化２】

（式中、Ｒ₁は水素，アルキル基，アリール基又はアルコキシ基を示し、Ｒ₂はアルキレン基又はフェニレン基を示し、Ｒ₃及びＲ₄は水素，アルキル基又はアリール基を示し、Ｒ₅は含窒素複素環基を示す）。
【０１２０】
上記アルキル基，アリール基，アルキレン基，フェニレン基は窒素原子を有するオルガノ基を有していても良いし、ハロゲン等の置換基を有していても良い。
【０１２１】
上述のシリコーンオイルは、トナーの帯電特性を高めるため、トナー粒子と同極性のものを用いることが好ましい。
【０１２２】
シリカをシリコーンオイル処理する方法としては、公知の技術が用いられる。
【０１２３】
例えば無機微粉体とシリコーンオイルとをヘンシェルミキサーの如き混合機を用いて直接混合しても良いし、無機微粉体へシリコーンオイルを噴霧する方法によっても良い。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、無機微粉体とを混合し、その後、溶剤を除去して作製しても良い。
【０１２４】
シリコーンオイルは、処理を施すシリカ１００質量部に対して、１．５〜６０質量部、好ましくは３．５〜４０質量部用いるのが良い。１．５乃至６０質量部であると、シリコーンオイルによる表面処理が均一におこなえ、好適にフィルミング及び中抜けを防止でき、高湿下での吸湿によるトナーの帯電性の低下を防止し、耐久における画像濃度の低下を防止し得る。サーフ定着を用いた場合は、定着飛び散りといった画像欠陥の発生を防止し得る。トナーの流動性の低下を防止し、カブリの発生も防止し得る。
【０１２５】
シリカの疎水率は９５％以上、好ましくは９７％以上のものが好ましい。疎水率は９５％以上であると、耐湿性が向上し、高湿下での画像濃度低下を引き起こす。
【０１２６】
更に、コロナ帯電方式や磁気ブラシ帯電方式と異なり、ローラー帯電方式の画像形成装置においては帯電ローラーと感光体がある圧力を持って接しながら回転している。特にクリーニングブレードのないクリーナーレスシステムにおいては転写残のトナーがそのニップを通過することになり、ローラーや感光体へのトナー、外添剤の融着が起こりやすい状況にある。その場合、特に粒径の大きなシリカ微粉体（Ａ）をシリコーンオイル処理することが好ましい。
【０１２７】
さらには、微粉体（Ａ）には本発明に必要な０．１μｍ以上１μｍ未満の範囲の複合粒子の量および融着防止効果のための２０μｍ以上１００μｍ未満の範囲の複合粒子の量の両者をコントロールすることが好ましい。その方法としては、分級処理または解砕処理を行っても良い。
【０１２８】
方法としてはエアー分級機等の粒度選別を行う方法やローターが回転して衝撃により複合粒子をほぐす方法（例えばハイブリタイザー、コスモマイザー等）や粉砕に用いられるピンミル、ジェットミル等の方法が挙げられるが、本発明の粒度分布に制御できる装置については限定はない。
【０１２９】
本発明に用いられる微粉体（Ａ），（Ｂ）の他に、帯電量の調整や、流動性の補助等のためさらに微粉末を添加しても良い。
【０１３０】
例えば流動性付与剤としては、金属酸化物（酸化ケイ素、酸化アルミニウム、酸化チタンなど）カーボンブラック、シリカなどが挙げられ、それぞれ、疎水化処理を行ったものが、より好ましい。
【０１３１】
研磨剤としては、金属酸化物（チタン酸ストロンチウム、酸化セリウム、酸化アルミニウム、酸化マグネシウム、酸化クロムなど）・窒化物（窒化ケイ素など）・炭化物（炭化ケイ素など）・金属塩（硫酸カルシウム、硫酸バリウム、炭酸カルシウムなど）が挙げられる。
【０１３２】
荷電制御性粒子としては、金属酸化物（酸化錫、酸化チタン、酸化亜鉛、酸化ケイ素、酸化アルミニウムなど）・カーボンブラックなどが挙げられる。
【０１３３】
本発明のトナーに離型剤を用いることも、オイルレス定着を達成するための良好な形態である。本発明に使用可能な離型剤としては、パラフィンワックス、ポリオレフィンワックス、マイクロクリスタリンワックス、フィッシャートロプシュワックス等のポリメチレンワックス、アミドワックス、高級脂肪酸、長鎖アルコール、ケトンワックス、エステルワックス及びこれらのグラフト化合物、ブロック化合物等の誘導体が挙げられ、必要に応じて蒸留などしても構わない。
【０１３４】
また、下記一般構造式で示すエステルワックスが特に好ましい。
【０１３５】
【化３】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基であり且つＲ₁とＲ₂との炭素数の差が３以上である基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない）
【０１３６】
【化４】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁は炭素数が１〜４０の有機基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない）
【０１３７】
【化５】

（式中、ａ及びｂは０〜３の整数を示し、ａ＋ｂは３以下であり、ｋは１乃至３の整数であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基であり且つＲ₁とＲ₂との炭素数の差が３以上である基を示し、Ｒ₃は炭素数が１以上の有機基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない。）
【０１３８】
本発明のトナーに含有される離型剤の半値幅は、ＡＳＴＭ Ｄ３４１８−８２に準拠して測定される。ここでいう吸熱ピークの半値幅とは、吸熱ピークにおけるベースラインからピークの高さの２分の１の吸熱チャートの温度幅である。離型剤の吸熱ピーク半値幅は１５℃以下であることが好ましく、より好ましくは７℃以下である。
【０１３９】
上記半値幅が１５℃を超える場合には、結晶性が高くないことから、離型剤の硬度も軟らかく、感光体や帯電ローラーへの汚染を促進させてしまう。
【０１４０】
また、本発明における離型剤のＤＳＣ吸熱曲線における吸熱ピーク値はＡＳＴＭ Ｄ３４１８−８２に準拠して測定される。
【０１４１】
本発明で用いられる離型剤は、上記ＤＳＣ曲線における吸熱ピーク値が５０〜１５０℃の値を示す化合物であることが好ましく、６０〜１２０℃の値を示す化合物であることがより好ましい。
【０１４２】
吸熱ピーク値が５０℃未満であると離型剤の自己凝集力が弱い為に、トナー粒子の内部又は中心部を構成しづらく、トナー粒子の製造時にトナー粒子表面に離型剤が析出し、感光体や帯電ローラーを汚染しやすい。
【０１４３】
一方、吸熱ピークが１５０℃を超えると、定着時に離型剤が浸み出しにくく、低温時の定着性や、トナー現像量が多い２次色（レッド、グリーン、ブルー）の定着性が低下する。更に、直接重合方法によりトナー粒子を生成する場合には、重合性単量体組成物中への溶解性が低下し、水系媒体中での重合性単量体組成物のトナー粒子径サイズへの液滴の造粒中に離型剤が析出して造粒が困難となり好ましくない。
【０１４４】
離型剤の分子量としては、質量平均分子量（Ｍｗ）が３００〜１，５００のものが好ましい。３００未満になると離型剤のトナー粒子表面への露出が生じ易く、現像性が悪化し、高温高湿環境下でカブリが生じやすい。また、帯電ローラーの汚染も著しい。一方、離型剤の質量平均分子量が１，５００を超えると、低温定着性が低下しかつ、ＯＨＴ透明性も悪化する。
【０１４５】
上記離型剤の質量平均分子量としては、４００〜１，２５０の範囲のものが特に好ましい。更に、質量平均分子量／数平均分子量の比（Ｍｗ／Ｍｎ）が１．５以下になると、離型剤のＤＳＣ吸熱曲線の極大ピークがよりシャープになり、室温時のトナー粒子の機械的強度が向上し、定着時にはシャープな溶融特性を示す、特に優れたトナー物性が得られる。
【０１４６】
上記離型剤の針入度は１５度以下、より好ましくは８度以下である。１５度を超える場合には、離型剤の半値幅が１０℃を超える場合と同様に、感光体や帯電ローラーの汚染を促進させてしまう。
【０１４７】
離型剤は結着樹脂１００質量部に対し、１乃至３５質量部、好ましくは５乃至３０質量部配合するのが良い。
【０１４８】
本発明のトナーに使用される結着樹脂としては、下記の結着樹脂の使用が可能である。
【０１４９】
例えば、ポリスチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如きスチレンおよびその置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体の如きスチレン系共重合体；ポリ塩化ビニル；フェノール樹脂；天然変性フェノール樹脂；天然変性マレイン酸樹脂；アクリル樹脂；メタクリル樹脂；ポリ酢酸ビニール；シリコーン樹脂；ポリエステル樹脂；ポリウレタン；ポリアミド樹脂；フラン樹脂；エポキシ樹脂；キシレン樹脂；ポリビニルブチラール；テルペン樹脂；クマロンインデン樹脂；石油系樹脂が使用できる。好ましい結着物質としては、スチレン系共重合体もしくはポリエステル樹脂があげられる。
【０１５０】
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およびその置換体；例えば、塩化ビニル、酢酸ビニル、安息香酸ビニルの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；の如きビニル系単量体が単独もしくは２つ以上用いられる。
【０１５１】
スチレン系重合体またはスチレン系共重合体は架橋されていても良く、さらに架橋されている樹脂と架橋されていない樹脂との混合樹脂でも良い。
【０１５２】
結着樹脂の架橋剤としては、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を用いてもよい。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、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；例えば、ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホンの如きジビニル化合物；および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用いられる。
【０１５３】
架橋剤の添加量としては、重合性単量体１００質量部に対して０．００１〜１０質量部が好ましい。
【０１５４】
本発明のトナーは、荷電制御剤を含有しても良い。
【０１５５】
トナーを負荷電性に制御するものとして下記物質がある。
【０１５６】
例えば、有機金属化合物、キレート化合物が有効であり、モノアゾ金属化合物、アセチルアセトン金属化合物、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属化合物がある。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類などがある。また、尿素誘導体、含金属サリチル酸系化合物、含金属ナフトエ酸系化合物、ホウ素化合物、４級アンモニウム塩、カリックスアレーン、ケイ素化合物、スチレン−アクリル酸共重合体、スチレン−メタクリル酸共重合体、スチレン−アクリル−スルホン酸共重合体、ノンメタルカルボン酸系化合物等が挙げられる。また、上記荷電制御化合物をペンダントした樹脂をトナー中に内添させても良い。
【０１５７】
トナーを正荷電性に制御するものとして下記物質がある。
【０１５８】
例えば、ニグロシン及び脂肪酸金属塩等による変性物、グアニジン化合物、イミダゾール化合物、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などの４級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドなどの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などのジオルガノスズボレート類；これらを単独で或は２種類以上組合せて用いることができる。これらの中でも、ニグロシン系、４級アンモニウム塩の如き荷電制御剤が特に好ましく用いられる。また、上記荷電制御化合物をペンダントした樹脂をトナー中に内添させても良い。
【０１５９】
これらの荷電制御剤は、樹脂成分１００質量部に対して、０．０１〜２０質量部（より好ましくは０．５〜１０質量部）使用するのが良い。
【０１６０】
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，グラフト化カーボンや以下に示すイエロー／マゼンタ／シアン着色剤を用い黒色に調色されたものが利用される。
【０１６１】
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等が用いられる。具体的には、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ３、７、１０、１２、１３、１４、１５、１７、２３、２４、６０、６２、７４、７５、８３、９３、９４、９５、９９、１００、１０１、１０４、１０８、１０９、１１０、１１１、１１７、１２３、１２８、１２９、１３８、１３９、１４７、１４８、１５０、１５５、１６６、１６８、１６９、１７７、１７９、１８０、１８１、１８３、１８５、１９１、１９２、１７０、１９９等が好適に用いられる。
【０１６２】
また、染料としてＣ．Ｉ．Ｓｏｌｖｅｎｔ Ｙｅｌｌｏｗ３３、５６、７９、８２、９３、１１２、１６２、１６３、Ｃ．Ｉ．Ｄｉｓｐｅｒｓｅ Ｙｅｌｌｏｗ４２、６４、２０１、２１１等があげられる。
【０１６３】
また、必要に応じてイエロー顔料、染料を単独で使用しても、もしくは数種の顔料や染料を併用しても良い。
【０１６４】
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，アントラキノン，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，ペリレン化合物等が用いられる。具体的には、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１２２、１４６、１５０、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２３８、２５４、２６９やＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｖｉｏｌｅｔ１９等が特に好ましい。
【０１６５】
また、必要に応じてマゼンタ顔料、染料を単独で使用しても、もしくは数種の顔料や染料を併用しても良い。
【０１６６】
本発明に用いられる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，アントラキノン化合物，塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ１、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。
【０１６７】
また、必要に応じてシアン顔料、染料を単独で使用しても、もしくは数種の顔料や染料を併用しても良い。
【０１６８】
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。本発明の着色剤は、色相角，彩度，明度，耐候性，ＯＨＰ透明性，トナー中への分散性の点から選択される。該着色剤の添加量は、樹脂１００質量部に対し１〜２０質量部添加して用いられる。
【０１６９】
次に本発明に用いられるトナーを製造するための方法について説明する。本発明に用いられるトナーは、粉砕トナー製法及び重合トナー製法を用いて製造することが可能である。
【０１７０】
本発明において、粉砕トナーの製造方法は結着樹脂、低軟化点物質、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機により充分混合し；得られた混合物を加熱ロール、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、樹脂成分を互いに相溶せしめた中に低軟化点物質、顔料、染料、磁性体を分散又は溶解せしめ；得られた混練物を冷却固化後粉砕及び分級を行ってトナーを得ることができる。
【０１７１】
さらに必要に応じてトナーと所望の添加剤をヘンシェルミキサーの如き混合機により充分混合し、本発明に用いられるトナーを得ることができる。
【０１７２】
本発明において、重合トナーの製造方法は、特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報，特開昭５９−５３８５６号公報，特開昭５９−６１８４２号公報に述べられている懸濁重合法を用いて直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合法又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合法に代表される乳化重合法や、予め１次極性乳化重合粒子を作った後、反対電荷を有する極性粒子を加え会合させるヘテロ凝集法等を用いトナーを製造することが可能である。
【０１７３】
しかしながら、分散重合法においては、得られるトナーは極めてシャープな粒度分布を示すが、使用する材料の選択が狭い事や有機溶剤の利用が廃溶剤の処理や溶剤の引火性に関する観点から製造装置が複雑で煩雑化しやすい。ソープフリー重合に代表される乳化重合法は、トナーの粒度分布が比較的揃うため有効であるが、使用した乳化剤や開始剤末端がトナー粒子表面に存在した時に環境特性を悪化させやすい。
【０１７４】
従って、本発明においては比較的容易に粒度分布がシャープな微粒子トナーが得られる常圧下での、または、加圧下での懸濁重合法が特に好ましい。一旦得られた重合粒子に更に単量体を吸着せしめた後、重合開始剤を用い重合せしめる所謂シード重合方法も本発明に好適に利用することができる。
【０１７５】
本発明のトナー製造方法に直接重合方法を用いる場合においては、以下の如き製造方法によって具体的にトナーを製造することが可能である。単量体中に低軟化点物質，着色剤，荷電制御剤，重合開始剤その他の添加剤を加え、ホモジナイザー，超音波分散機等によって均一に溶解又は分散せしめた単量体系を、分散安定剤を含有する水相中に通常の撹拌機またはホモミキサー，ホモジナイザー等により分散せしめる。好ましくは単量体液滴が所望のトナー粒子のサイズを有するように撹拌速度・時間を調整し、造粒する。その後は分散安定剤の作用により、粒子状態が維持され、且つ粒子の沈降が防止される程度の撹拌を行えば良い。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行う。また、重合反応後半に昇温しても良く、更に、トナー定着時の臭いの原因等となる未反応の重合性単量体、副生成物等を除去するために反応後半、又は、反応終了後に一部水系媒体を留去しても良い。反応終了後、生成したトナー粒子を洗浄・濾過により回収し、乾燥する。懸濁重合法においては、通常単量体系１００質量部に対して水３００〜３０００質量部を分散媒として使用するのが好ましい。
【０１７６】
本発明に用いられるより好ましいトナーは、透過電子顕微鏡（ＴＥＭ）を用いたトナーの断層面測定法で低軟化点物質が、外殻樹脂層で内包化された直接重合法を用いて製造されたものである。定着性の観点から多量の低軟化点物質をトナーに含有せしめる必要性から、必然的な低軟化点物質を外殻樹脂中に内包化せしめる必要がある。内包化せしめない場合のトナーは、粉砕工程において特殊な凍結粉砕を利用しないと十分な微粉砕化ができず結果的に粒度分布の広いものしか得られず、装置へのトナー融着も発生し甚だ好ましくない。また冷凍粉砕においては、装置への結露防止策のため装置が煩雑化したり、仮にトナーが吸湿した場合においてはトナーの作業性低下を招き、更に乾燥工程を追加することも必要となり問題となる。該低軟化点物質を内包化せしめる具体的な方法としては、水系媒体中での材料の極性を主要単量体より低軟化点物質の方を小さく設定し、更に少量の極性の大きな樹脂又は単量体を添加せしめることで低軟化点物質を外殻樹脂で被覆した所謂コア−シェル構造を有するトナーを得ることができる。トナーの粒度分布制御や粒径の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件例えばローターの周速・パス回数・撹拌羽根形状等の撹拌条件や容器形状又は、水溶液中での固形分濃度等を制御することにより所定の本発明のトナーを得ることができる。
【０１７７】
本発明においてトナーの断層面を測定する具体的な方法としては、常温硬化性のエポキシ樹脂中にトナーを十分分散させた後温度４０℃の雰囲気中で２日間硬化させ得られた硬化物を四三酸化ルテニウム、必要により四三酸化オスミウムを併用し染色を施した後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出し透過電子顕微鏡（ＴＥＭ）を用いトナーの断層形態を測定した。本発明においては、用いる該低軟化点物質と外殻を構成する樹脂との若干の結晶化度の違いを利用して材料間のコントラストを付けるため四三酸化ルテニウム染色法を用いることが好ましい。
【０１７８】
重合法によりトナーを製造する場合に用いられるラジカル重合が可能なビニル系重合性単量体としては、単官能性重合性単量体あるいは多官能性重合性単量体を使用することができる。
【０１７９】
単官能性重合性単量体としては、スチレン、α−メチルスチレン、β−メチルスチレン、ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、２，４−ジメチルスチレン、ｐ−ｎ−ブチルスチレン、ｐ−ｔｅｒｔ−ブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレン、ｐ−メトキシスチレン、ｐ−フェニルスチレンなどのスチレン系重合性単量体；メチルアクリレート、エチルアクリレート、ｎ−プロピルアクリレート、ｉｓｏ−プロピルアクリレート、ｎ−ブチルアクリレート、ｉｓｏ−ブチルアクリレート、ｔｅｒｔ−ブチルアクリレート、ｎ−アミルアクリレート、ｎ−ヘキシルアクリレート、２−エチルヘキシルアクリレート、ｎ−オクチルアクリレート、ｎ−ノニルアクリレート、シクロヘキシルアクリレート、ベンジルアクリレート、ジメチルフォスフェートエチルアクリレート、ジブチルフォスフェートエチルアクリレート、２−ベンゾイルオキシエチルアクリレートなどのアクリル系重合性単量体；メチルメタクリレート、エチルメタクリレート、ｎ−プロピルメタクリレート、ｉｓｏ−プロピルメタクリレート、ｎ−ブチルメタクリレート、ｉｓｏ−ブチルメタクリレート、ｔｅｒｔ−ブチルメタクリレート、ｎ−アミルメタクリレート、ｎ−ヘキシルメタクリレート、２−エチルヘキシルメタクリレート、ｎ−オクチルメタクリレート、ｎ−ノニルメタクリレート、ジエチルフォスフェートエチルメタクリレート、ジブチルフォスフェートエチルメタクリレートなどのメタクリル系重合性単量体；メチレン脂肪族モノカルボン酸エステル類；酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニル、酪酸ビニル、安息香酸ビニル、ギ酸ビニルなどのビニルエステル類；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテル等のビニルエーテル類、ビニルメチルケトン、ビニルヘキシルケトン、ビニルイソプロピルケトン等のビニルケトン類などのビニル系重合性単量体等が挙げられる。
【０１８０】
多官能性重合性単量体としては、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、トリプロピレングリコールジアクリレート、ポリプロピレングリコールジアクリレート、２，２’−ビス［４−（アクリロキシ・ジエトキシ）フェニル］プロパン、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、エチレングリコールジメタクリレート、ジエチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、テトラエチレングリコールジメタクリレート、ポリエチレングリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、１，６−ヘキサンジオールジメタクリレート、ネオペンチルグリコールジメタクリレート、ポリプロピレングリコールジメタクリレート、２，２’−ビス［４−（メタクリロキシ・ジエトキシ）フェニル］プロパン、２，２’−ビス［４−（メタクリロキシ・ポリエトキシ）フェニル］プロパン、トリメチロールプロパントリメタクリレート、テトラメチロールメタンテトラメタクリレート、ジビニルベンゼン、ジビニルナフタリン、ジビニルエーテル等を挙げることができる。
【０１８１】
前記単官能性重合性単量体を単独あるいは２種以上組み合わせて、また、単官能性重合性単量体と多官能性重合性単量体を組み合わせて使用することができる。また、前記多官能性重合性単量体を架橋剤として使用することも可能である。
【０１８２】
本発明において、トナーにコアーシェル構造を形成せしめるためには、極性樹脂を併用することが好ましい。本発明に使用できる極性重合体及び極性共重合体の如き極性樹脂を以下に例示する。
【０１８３】
極性樹脂としては、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如き含窒素単量体の重合体もしくは含窒素単量体とスチレン−不飽和カルボン酸エステルとの共重合体；アクリロニトリルの如きニトリル系単量体；塩化ビニルの如き含ハロゲン系単量体；アクリル酸、メタクリル酸の如き不飽和カルボン酸；不飽和二塩基酸；不飽和二塩基酸無水物；ニトロ系単量体の重合体もしくはそれとスチレン系単量体との共重合体；ポリエステル；エポキシ樹脂；が挙げられる。より好ましいものとして、スチレンと（メタ）アクリル酸の共重合体、マレイン酸共重合体、飽和または不飽和のポリエステル樹脂、エポキシ樹脂が挙げられる。
【０１８４】
重合開始剤としては、例えば、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリル等のアゾ系又はジアゾ系重合開始剤、ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、ｔ−ブチルヒドロペルオキシド、ジ−ｔ−ブチルペルオキシド、ジクシルペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシド、２，２−ビス（４，４−ｔ−ブチルペルオキシシクロヘキシル）プロパン、トリス−（ｔ−ブチルペルオキシ）トリアジンなどの過酸化物系開始剤や過酸化物を側鎖に有する高分子開始剤、過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩、過酸化水素などが使用される。
【０１８５】
重合開始剤は重合性単量体の０．５〜２０質量部の添加量が好ましく、単独で又は、併用しても良い。
【０１８６】
また、本発明では分子量をコントロールするために、公知の架橋剤、連鎖移動剤を添加しても良く、好ましい添加量としては０．００１〜１５質量部である。
【０１８７】
本発明において、乳化重合，分散重合，懸濁重合，シード重合，ヘテロ凝集法を用いる重合法等によって、重合法トナーを製造する際に用いられる分散媒には、いずれか適当な安定剤を使用する。例えば、無機化合物として、リン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナ等が挙げられる。有機化合物として、ポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、ポリアクリル酸及びその塩、デンプン、ポリアクリルアミド、ポリエチレンオキシド、ポリ（ハイドロオキシステアリン酸−ｇ−メタクリル酸メチル−ｅｕ−メタクリル酸）共重合体やノニオン系或はイオン系界面活性剤などが使用される。
【０１８８】
また、乳化重合法及びヘテロ凝集法を用いる場合には、アニオン系界面活性剤、カチオン系界面活性剤、両性イオン界面活性剤及びノニオン系界面活性剤が使用される。これらの安定剤は重合性単量体１００質量部に対して０．２〜３０質量部を使用することが好ましい。
【０１８９】
これら安定化剤の中で、無機化合物を用いる場合、市販のものをそのまま用いても良いが、細かい粒子を得るために、分散媒中にて該無機化合物を生成させても良い。
【０１９０】
また、これら安定化剤の微細な分散の為に、０．００１〜０．１質量部の界面活性剤を使用してもよい。これは上記分散安定化剤の所期の作用を促進する為のものであり、その具体例としては、ドデシルベンゼン硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等が挙げられる。
【０１９１】
本発明のトナーは、通常一成分及び二成分系現像剤用として使用できる。一成分系現像剤として、磁性体を含有しない非磁性トナーを用いる場合には、ブレード又はローラを用い、現像スリーブにて強制的に摩擦帯電しスリーブ上にトナーを付着せしめることで搬送せしめる方法がある。
【０１９２】
本発明のトナーはトナーのみからなる（キャリアを有さない）一成分現像剤として用いられるものであっても、トナーとキャリアとからなる二成分現像剤として用いられるものであってもよいが、本発明のトナーはフルカラーの画像形成方法にも好適に用いることができるため、二成分現像剤として好適に用いることができる。
【０１９３】
次に本発明を二成分現像で使用する場合の使用可能なキャリアについて説明をする。
【０１９４】
キャリアの５０％粒径が１５μｍ未満である場合には、キャリアの粒度分布の微粒子側の粒子による非画像部へのキャリア付着を良好に防止できない場合がある。キャリアの５０％粒径が６０μｍより大きい場合には、磁気ブラシの剛直さによるはきめは生じないが、大きさ故の画像のムラを生じてしまう場合がある。
【０１９５】
本発明において、キャリアコアに用いる金属化合物粒子としては、下記式（１）又は（２）で表される磁性を有するマグネタイト又はフェライトが挙げられる。
【０１９６】
ＭＯ・Ｆｅ₂Ｏ₃ ・・・（１）
Ｍ・Ｆｅ₂Ｏ₄ ・・・（２）
（式中、Ｍは３価、２価又は１価の金属イオンを示す。）
【０１９７】
Ｍとしては、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｓｒ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｃｄ、Ｓｎ、Ｂａ、Ｐｂ及びＬｉが挙げられ、こえらは、単独あるいは複数で用いることができる。
【０１９８】
上記の磁性を有する金属化合物粒子の具体的化合物としては、例えば、マグネタイト、Ｚｎ−Ｆｅ系フェライト、Ｍｎ−Ｚｎ−Ｆｅ系フェライト、Ｎｉ−Ｚｎ−Ｆｅフェライト、Ｍｎ−Ｍｇ−Ｆｅ系フェライト、Ｃａ−Ｍｎ−Ｆｅ系フェライト、Ｃａ−Ｍｇ−Ｆｅ系フェライト、Ｌｉ−Ｆｅ系フェライト及びＣｕ−Ｚｎ−Ｆｅ系フェライトの如き鉄系酸化物が挙げられる。
【０１９９】
さらに、本発明において、キャリアコアに用いる金属化合物粒子としては、上記の磁性を有する金属化合物と下記の非磁性の金属化合物とを混合して用いても良い。
【０２００】
非磁性の金属化合物としては、例えば、Ａｌ₂Ｏ₃、ＳｉＯ₂、ＣａＯ、ＴｉＯ₂、Ｖ₂Ｏ₅、ＣｒＯ、ＭｎＯ₂、α−Ｆｅ₂Ｏ₃、ＣｏＯ、ＮｉＯ、ＣｕＯ、ＺｎＯ、ＳｒＯ、Ｙ₂Ｏ₃及びＺｒＯ₂が挙げられる。この場合、１種類の金属化合物を用いることもできるが、とくに好ましくは少なくとも２種以上の金属化合物を混合して用いるのが良い。その場合には、比重や形状が類似している粒子を用いるのが結着樹脂との密着性及びキャリアコア粒子の強度を高めるためにより好ましい。
【０２０１】
組み合わせの具体例としては、例えば、マグネタイトとヘマタイト、マグネタイトとｒ−Ｆｅ₂Ｏ₃、マグネタイトとＳｉＯ₂、マグネタイトとＡｌ₂Ｏ₃、マグネタイトとＴｉＯ₂、マグネタイトとＣａ−Ｍｎ−Ｆｅ系フェライト、マグネタイトとＣａ−ＭｇＦｅ系フェライトが好ましく用いることができる。中でもマグネタイトとヘマタイトの組み合わせが特に好ましく用いることができる。
【０２０２】
本発明に用いるキャリアコア粒子の結着樹脂としては、熱硬化性樹脂であり、一部または全部が３次元的に架橋されている樹脂であることが好ましい。このことにより、分散する金属化合物粒子を強固に結着できるため、キャリアコアの強度を高めることができ、多数枚の複写においても金属化合物の脱離が起こリ難く、さらに、被覆樹脂を、より良好に被覆することができ、その結果、吸着水分量を本発明の範囲内に制御することが容易になる。
【０２０３】
磁性体分散型キャリアコアを得る方法としては、特に以下に記載する方法に限定されるものではないが、本発明においては、モノマーと溶媒が均一に分散又は溶解されているような溶液中から、モノマーを重合させることにより粒子を生成する重合法の製造方法、特に、キャリアコア粒子中に分散する金属酸化物に、親油化処理を施すことにより、粒度分布のシャープな、微粉の少ない磁性体分散型樹脂キャリアコアを得る方法が、好適に用いられる。
【０２０４】
本発明においては、高画質化を達成するために重量平均粒径が４〜１０μｍの小粒径トナーと組み合わせて用いられるキャリアの場合、キャリア粒径もトナーの粒径に応じて小粒径化することが好ましく、上述した製造方法ではキャリア粒径を小粒径化させても平均粒径に関係なく微粉の少ないキャリアを製造できることから特に好ましい。
【０２０５】
キャリアコア粒子の結着樹脂に使用されるモノマーとしては、ラジカルの重合性モノマーを用いることができる。例えばスチレン；ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メトキシスチレン、ｐ−エチルスチレン、ｐ−ターシャリーブチルスチレンの如きスチレン誘導体；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ｎ−ブチル、アクリル酸ｎ−プロピル、アクリル酸イソブチル、アクリル酸オクチル、アクリル酸ドデシル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸２−クロルエチル、アクリル酸フェニルの如きアクリル酸エステル；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ｎ−プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、メタクリル酸２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸フェニル、メタクリル酸ジメチルアミノメチル、メタクリル酸ジエチルアミノエチル、メタクリル酸ベンジルの如きメタクリル酸エステル類；２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート；アクリロニトリル、メタクリロニトリル、アクリルアミド；メチルビニルエーテル、エチルビニルエーテル、プロピルビニルエーテル、ｎ−ブチルエーテル、イソブチルエーテル、β−クロルエチルビニルエーテル、フェニルビニルエーテル、ｐ−メチルフェニルエーテル、ｐ−クロルフェニルエーテル、ｐ−ブロムフェニルエーテル、ｐ−ニトロフェニルビニルエーテル、ｐ−メトキシフェニルビニルエーテルの如きビニルエーテル；ブタジエンの如きジエン化合物を挙げることができる。
【０２０６】
これらのモノマーは単独または混合して使用することができ、好ましい特性が得られるような好適な重合体組成を選択することができる。
【０２０７】
前述したように、キャリアコア粒子の結着樹脂は３次元的に架橋されていることが好ましいが、結着樹脂を３次元的に架橋させるための架橋剤としては、重合性の２重結合を一分子当たり２個以上有する架橋剤を使用することが好ましい。このような架橋剤としては、例えば、ジビニルベンゼン、ジビニルナフタレンの如き芳香族ジビニル化合物；エチレングリコールジアクリレート、エチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、テトラエチレングリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、トリメチロールプロパントリアクリレート、トリメチロールプロパントリメタクリレート、１，４−ブタンジオールジアクリレート、ネオペンチルグリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、ペンタエリスリトールジメタクリレート、ペンタエリスリトールテトラメタクリレート、グリセロールアクロキシジメタクリレート、Ｎ，Ｎ−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フォンが挙げられる。これらは、２種類以上を適宜混合して使用しても良い。架橋剤は、重合性混合物にあらかじめ混合しておくこともできるし、必要に応じて適宜重合の途中で添加することもできる。
【０２０８】
その他のキャリアコア粒子の結着樹脂のモノマーとして、エポキシ樹脂の出発原料としてなるビスフェノール類とエピクロルヒドリン；フェノール樹脂のフェノール類とアルデヒド類；尿素樹脂の尿素とアルデヒド類；メラミンとアルデヒド類が挙げられる。
【０２０９】
もっとも好ましい結着樹脂は、フェノール系樹脂である。その出発原料としては、フェノール、ｍ−クレゾール、３，５−キシレノール、ｐ−アルキルフェノール、レゾルシル、ｐ−ｔｅｒｔ−ブチルフェノールの如きフェノール化合物、ホルマリン、パラホルムアルデヒド、フルフラールの如きアルデヒド化合物が挙げられる。特にフェノールとホルマリンの組み合わせが好ましい。
【０２１０】
これらのフェノール樹脂又はメラミン樹脂を用いる場合には、硬化触媒として塩基性触媒を用いることができる。塩基性触媒として通常のレゾール樹脂製造に使用される種々のものを用いることができる。具体的にはアンモニア水、ヘキサメチレンテトラミン、ジエチルトリアミン、ポリエチレンイミンの如きアミン類を挙げることができる。
【０２１１】
本発明において、キャリアコアに含有される金属化合物は、親油化処理されていることが磁性キャリア粒子の粒度分布をシャープにすること及び金属化合物粒子のキャリアからの脱離を防止する上で好ましい。親油化処理された金属化合物を分散させたキャリアコア粒子を形成する場合、モノマーと溶媒が均一に分散又は溶解している液中から重合反応が進むと同時に溶液に不溶化した粒子が生成する。そのときに金属酸化物が粒子内部で均一に、かつ高密度に取り込まれる作用と粒子同士の凝集を防止し粒度分布をシャープ化する作用があると考えられる。更に、親油化処理を施した金属化合物を用いた場合、フッ化カルシウムの如き懸濁安定剤を用いる必要がなく、懸濁安定剤がキャリア表面に残存することによる帯電性阻害、コート時におけるコート樹脂の不均一性、シリコーン樹脂の如き反応性樹脂をコートした場合における反応阻害を防止することができる。また、懸濁安定剤が表面に存在しないこと及び、それに付随する弊害を無くすことで、吸着水分量を本発明の範囲内に制御することを容易にしている。
【０２１２】
親油化処理は、エポキシ基、アミノ基及びメルカプト基から選ばれた、１種又は２種以上の官能基を有する有機化合物や、それらの混合物である親油化処理剤で処理されていることが好ましい。特に、本発明の吸着水分量の範囲を容易に達成し、帯電付与能が安定したキャリアを得るためには、エポキシ基が好ましく用いられる。
【０２１３】
磁性金属酸化物粒子は、磁性金属酸化物粒子１００質量部当り好ましくは０．１〜１０質量部、より好ましくは０．２〜６質量部の親油化処理剤で処理されているのが磁性金属酸化物粒子の親油性及び疎水性を高める上で好ましい。
【０２１４】
エポキシ基を有する親油化処理剤としては、γ−グリシドキシプロピルメチルジエトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、β−（３，４−エポキシシクロヘキシル）トリメトキシシラン、エピクロルヒドリン、グリシドール及びスチレン−（メタ）アクリル酸グリシジル共重合体が挙げられる。
【０２１５】
アミノ基を持つ親油化処理剤としては、例えば、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルメトキシジエトキシシラン、γ−アミノプロピルトリエトキシシラン、Ｎ−β（アミノエチル）−γ−アミノプロピルトリメトキシシラン、Ｎ−β（アミノエチル）−γ−アミノプロピルメチルジメトキシシラン、Ｎ−フェニル−γ−アミノプロピルトリメトキシシラン、エチレンジアミン、エチレントリアミン、スチレン−（メタ）アクリル酸ジメチルアミノエチル共重合体及びイソプロピルトリ（Ｎ−アミノエチル）チタネート等が用いられる。
【０２１６】
メルカプト基を有する親油化処理剤としては、例えば、メルカプトエタノール、メルカプトプロピオン酸及びγ−メルカプトプロピルトリメトキシシランが用いられる。
【０２１７】
キャリアコア表面を被覆する樹脂は、特に限定を受けるものではない。具体的には、例えば、ポリスチレン、スチレン−アクリル共重合体の如きアクリル樹脂、塩化ビニル、酢酸ビニル、ポリフッ化ビニリデン樹脂、フルオロカーボン樹脂、パーフロロカーボン樹脂、溶剤可溶性パーフロロカーボン樹脂、ポリビニルアルコール、ポリビニルアセタール、ポリビニルピロリドン、石油樹脂、セルロース、セルロース誘導体、ノボラック樹脂、低分子量ポリエチレン、飽和アルキルポリエステル樹脂、芳香族ポリエステル樹脂、ポリアミド樹脂、ポリアセタール樹脂、ポリカーボネート樹脂、ポリエーテルスルホン樹脂、ポリスルホン樹脂、ポリフェニレンサルファイド樹脂、ポリエーテルケトン樹脂、フェノール樹脂、変性フェノール樹脂、マレイン樹脂、アルキド樹脂、エポキシ樹脂、アクリル樹脂、無水マレインとテレフタル酸と多価アルコールとの重縮合によって得られる不飽和ポリエステル、尿素樹脂、メラミン樹脂、尿素−メラミン樹脂、キシレン樹脂、トルエン樹脂、グアナミン樹脂、メラミン−グアナミン樹脂、アセトグアナミン樹脂、グリプタール樹脂、フラン樹脂、シリコーン樹脂、ポリイミド樹脂、ポリアミドイミド樹脂、ポリエーテルイミド樹脂及びポリウレタン樹脂を挙げることができる。
【０２１８】
中でもシリコーン樹脂は、コアとの密着性、スペント防止の観点から、好ましく用いられる。シリコーン樹脂は、単独で用いることもできるが、被覆層の強度を高め好ましい帯電に制御するために、カップリング剤と併用して用いることが好ましい。更に、前述のカップリング剤は、その一部が、樹脂をコートする前に、キャリアコア表面に処理される、いわゆるプライマー剤として用いられることが好ましく、その後の被覆層が、共有結合を伴った、より密着性の高い状態で形成することができる。
【０２１９】
カップリング剤としては、アミノシランを用いると良い。その結果、ポジ帯電性を持ったアミノ基をキャリア表面に導入でき、良好にトナーに負帯電特性を付与できる。更に、アミノ基の存在は、金属化合物に好ましく処理されている親油化処理剤と、シリコーン樹脂の両者を活性化させるため、シリコーン樹脂のキャリアコアとの密着性を更に高め、同時に樹脂の硬化を促進することでより強固な被覆層を形成することができる。
【０２２０】
本発明で、使用したキャリアは必要に応じて下記測定方法により、物性測定を行った。
【０２２１】
キャリア粒子の体積基準の５０％粒径及び粒度分布の測定方法は、シンパテック（ＳＹＮＰＡＴＥＣ）社製で乾式分散機（ロドス＜ＲＯＤＯＳ＞）を備えたレーザー回折式粒度分布測定装置（へロス＜ＨＥＬＯＳ＞）を用いて、フィードエア圧力３ｂａｒ、吸引圧力０．１ｂａｒの条件で測定した。
【０２２２】
キャリア粒径は、体積基準による５０％粒径（Ｄ）が好ましくは１５〜６０μｍ、より好ましくは２５〜５０μｍ、さらに好ましくは３０〜４０μｍであることが本発明のトナーを良好に帯電させるために好ましい。さらにキャリアは、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が、好ましくは５体積％以下、より好ましくは０．１〜５体積％であることが良い。
【０２２３】
キャリアの磁気特性の測定は、理研電子（株）製の振動磁場型磁気特性自動記録装置ＢＨＶ−３５を用いて行う。測定としては、１０００／４π（ｋＡ／ｍ）の外部磁場を作り、そのときの磁化の強さを求める。円筒状のプラスチック容器にキャリア粒子が動かないように十分密になるようにパッキングし、この状態で磁化モーメントを測定し、試料を入れたときの実際の質量を測定して、磁化の強さ（Ａｍ²／ｋｇ）を求めた。
【０２２４】
二成分現像剤からキャリア物性を測定する場合は、コンタミノンＮ（界面活性剤）が１％含まれるイオン交換水にて現像剤を洗浄してトナーとキャリアとを分離した後、上記測定を行う。
【０２２５】
キャリアの比抵抗の測定は、真空理工（株）社製の粉体用絶縁抵抗測定器を用いて測定する。測定条件は、２３℃，６０％条件下に２４時間以上放置したキャリアを直径２０ｍｍ（０．２８３ｃｍ²）の測定セル中にいれ、１２０ｇ／ｃｍ²の荷重電極で挟み、厚みを２ｍｍとし、印加電圧を５００Ｖで測定する。
【０２２６】
キャリアの見かけ密度測定方法は、ＪＩＳ−Ｚ０２５０４に従って行う。
【０２２７】
以下、実施例の画像形成装置（画像記録装置）について具体的に説明する。しかし、これらは本発明を何ら限定するものではない。
【０２２８】
図１は本発明に従う画像形成装置例の概略構成模型図である。本例の画像形成装置は、転写方式電子写真プロセス利用、接触帯電方式、反転現像方式、クリーナレス、最大通紙サイズがＡ３サイズのレーザビームプリンタである。
【０２２９】
（１）プリンタの全体的概略構成
ａ）感光ドラム
１は回転ドラム型の電子写真感光体（以下、感光ドラムと記す）である。この感光ドラム１は、図２の層構成模型図のように、アルミニウム製シリンダ（導電性ドラム基体）１ａの表面に、光の干渉を抑え、上層の接着性を向上させる下引き層１ｂと、光電荷発生層１ｃと、電荷輸送層１ｄの３層を下から順に塗り重ねた構成をしている。
【０２３０】
本発明の感光ドラムは上記に限られるものではない。以下につぎに電子写真感光体の典型的な構成について、図３、図４および図５により説明する。
【０２３１】
感光層が有機光導電体を主成分として構成され、有機光導電体としては、ポリビニールカルバゾール等の有機光導電性ポリマーを用いたもの、あるいは低分子量の有機光導電性物質を結着樹脂中に含有したものなどがある。
【０２３２】
図３の電子写真感光体は、導電性支持体１６上に感光層１７が設けられており、この感光層１７は結着樹脂中に電荷発生物質１８を分散含有した電荷発生層１９と電荷輸送層２０の積層構造である。この場合電荷輸送層２０は、電荷発生層１９の上に積層されている。
【０２３３】
図４の電子写真感光体は、図３の場合と異なり、電荷輸送層２０は電荷発生層１９の下に積層されている。この場合、電荷発生層１９中には電荷輸送物質が含有されていてもよい。
【０２３４】
図５の電子写真感光体は、導電性支持体１６上に感光層１７が設けられており、この感光層１７は結着樹脂中に電荷発生物質１８と電荷輸送物質（図示せず）が含有されている。
【０２３５】
これらのうち、図３に示すように、導電性支持体１６側から電荷発生層１９、次いで、電荷輸送層２０の順で積層されている構造の感光体が本発明においては好ましい。
【０２３６】
導電性支持体１６としては、アルミニウム、ステンレスなどの金属、紙、プラスチックなどの円筒状シリンダー、シートまたはフィルムなどが用いられる。また、これらの円筒状シリンダー、シートまたはフィルムは、必要に応じて導電性ポリマー層、あるいは酸化スズ、酸化チタン、銀粒子などの導電性粒子を含有する樹脂層を有していてもよい。
【０２３７】
また、導電性支持体１６と感光層１７の間にはバリアー機能と下引き機能を持つ下引き層（接着層）を設けることができる。
【０２３８】
下引き層は感光層の接着性改良、塗工性改良、支持体の保護、支持体の欠陥の被覆、支持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などのために形成される。その膜厚は０．２〜２μｍ程度である。
【０２３９】
電荷発生物質としては、ビリリウム、チオピオリリウム系染料、フタロシアニン系顔料、アントアントロン顔料、ジベンズビレンキノン顔料、ピラトロン顔料、アゾ顔料、インジゴ顔料、キナクリドン系顔料、非対称キノシアニン、キノシアニンなどを用いることができる。
【０２４０】
電荷輸送物質としては、ヒドラゾン系化合物、ピラゾリン系化合物、スチリル系化合物、オキサゾール系化合物、チアゾール系化合物、トリアリールメタン系化合物、ポリアリールアルカン系化合物などを用いることができる。
【０２４１】
電荷発生層１９は、上記電荷発生物質を０．５〜４倍量の結着剤樹脂、および溶剤と共に、ホモジナイザー、超音波、ボールミル、振動ボールミル、サンドミル、アトライター、ロールミルなどの方法でよく分散し、塗布、乾燥されて形成される。その厚みは５μｍ以下、特には０．０１〜１μｍの範囲が好ましい。
【０２４２】
電荷輸送層２０は、一般的には上記電荷輸送物質と結着剤樹脂を溶剤に溶解し、塗布して形成する。電荷輸送物質と結着剤樹脂との混合割合は２：１〜１：２程度である。溶剤としては、アセトン、メチルエチルケトンなどのケトン類、酢酸メチル、酢酸エチルなどのエステル類、トルエン、キシレンなどの芳香族炭化水素類、クロルベンゼン、クロロホルム、四塩化炭素などの塩素系炭化水素類、などが用いられる。この溶液を塗布する際には、例えば浸漬コーティング法、スプレーコーティング法、スピンナーコーティング法などのコーティング法を用いることができ、乾燥は１０℃〜２００℃、好ましくは２０℃〜１５０℃の範囲の温度で５分〜５時間、好ましくは１０分〜２時間で送風乾燥または静止乾燥下で行うことができる。生成した電荷輸送層の膜厚は５〜３０μｍ、特には１０〜２５μｍの範囲が好ましい。
【０２４３】
電荷発生層１９および電荷輸送層２０を形成するのに用いられる結着樹脂としては、アクリル樹脂、スチレン系樹脂、ポリエステル、ポリカーボネート樹脂、ポリアリレート、ポリサルホン、ポリフェニレンオキシド、エポキシ樹脂、ポリウレタン樹脂、アルキド樹脂、および不飽和樹脂等から選ばれる樹脂が好ましい。特に好ましい樹脂としては、ポリメチルメタクリレート、ポリスチレン、スチレン−アクリロニトリル共重合体、ポリカーボネート樹脂またはジアリルフタレート樹脂が挙げられる。また、電荷発生層あるいは電荷輸送層には、酸化防止剤、紫外線吸収剤、潤滑剤など種々の添加剤を含有させることができる。
【０２４４】
ｂ）帯電手段
２は感光ドラム１の周面を一様に帯電処理する帯電手段としての接触帯電装置（接触帯電器）であり、本例は帯電ローラ（ローラ帯電器）である。
【０２４５】
この帯電ロ一ラ２は、芯金２ａの両端部をそれぞれ不図示の軸受け部材により回転自在に保持させると共に、押し圧ばね２ｅによって感光ドラム方向に付勢して感光ドラム１の表面に対して所定の押圧力をもって圧接させており、感光ドラム１の回転に従動して回転する。感光ドラム１と帯電ローラ２との圧接部が帯電部（帯電ニップ部）ａである。
【０２４６】
帯電ローラ２の芯金２ａには電源Ｓ１より所定の条件の帯電バイアス電圧が印加されることにより回転感光ドラム１の周面が所定の極性・電位に接触帯電処理される。本例において、帯電ローラ２に対する帯電バイアス電圧は直流電圧（Ｖｄｃ）と交流電圧（Ｖａｃ）とを重畳した振動電圧である。
直流電圧；−５００Ｖ
交流電圧；周波数ｆ１０００Ｈｚ、ピーク間電圧Ｖｐｐ１４００Ｖ、正弦波とを重畳した振動電圧であり、感光ドラム１の周面は−５００Ｖ（暗電位Ｖｄ）に一様に接触帯電処理される。
【０２４７】
帯電ローラ２の長手長さは３２０ｍｍであり、図４の層構成模型図のように、芯金（支持部材）２ａの外回りに、弾性層２ｂと、抵抗制御層２ｃと、表面層２ｄを下から順次に積層した３層構成である。弾性層２ｂは帯電音を低減するための発泡スポンジ層であり、抵抗制御層２ｃは帯電ローラ全体として均一な抵抗を得るための導電層であり、表面層２ｄは感光ドラム１上にピンホール等の欠陥があってもリークが発生するのを防止するために設けている保護層である。
【０２４８】
さらに詳細に説明する。
【０２４９】
図２において、２は帯電部材、２ａは導電性支持体、２ｂは弾性層、２ｃは抵抗制御層、２ｄは表面層を示す。帯電ローラは抵抗制御層２ｃのない弾性層２ｂと表面層２ｄの構成であってもよい。
【０２５０】
本発明に用いられる導電性支持体２ａは、鉄、銅、ステンレス、アルミニウム及びニッケル等の金属を用いることができる。更に、これらの金属表面に防錆や耐傷性付与を目的としてメッキ処理を施しても構わないが、導電性を損なわないことが必要である。
【０２５１】
帯電ローラ２において、弾性層２ｂには、帯電ローラ２の感光体１に対する良好な均一密着性を確保するために適当な弾性を持たせてある。
【０２５２】
弾性層２ｂの導電性はゴム等の弾性材料中にカーボンブラック等の導電性粒子あるいはアルカリ金属塩及びアンモニウム塩等の導電剤を添加することにより調整される。弾性はプロセス油及び可塑剤等の添加により調整される。弾性層２ｂの具体的弾性材料としては、例えば、天然ゴム、エチレンプロピレンジエンメチレンゴム（ＥＰＤＭ）、スチレン−ブタジエンゴム（ＳＢＲ）、シリコーンゴム、ウレタンゴム、エピクロルヒドリンゴム、イソプレンゴム（ＩＲ）、ブタジエンゴム（ＢＲ）、ニトリル−ブタジエンゴム（ＮＢＲ）及びクロロプレンゴム（ＣＲ）等の合成ゴム、更にはポリアミド樹脂、ポリウレタン樹脂、シリコーン樹脂及びフッ素樹脂等の樹脂も挙げられる。また、前述の弾性材料の発泡体を弾性層２ｂに用いてもよい。
【０２５３】
前記弾性層の電気抵抗は、１×１０³〜１×１０¹⁰［Ωｃｍ］の範囲の導電性を有していることが好ましい。また、膜厚は導電性支持体の径にもよるので、特に制限を受けるものではない。
【０２５４】
表面層２ｄは弾性層２ｂ中の可塑剤等の帯電ローラ表面へのブリードアウトを防止するためや帯電ローラ表面の滑り性や平滑性を維持するために設けることが多い。表面層２ｄは塗工あるいはチューブを被覆することによって設ける。
【０２５５】
表面層２ｄを塗工により設ける場合、具体的な材料としては、ポリアミド樹脂、ポリウレタン樹脂、アクリル樹脂、フッ素樹脂及びシリコーン樹脂等の樹脂、更にはエピクロルヒドリンゴム、ウレタンゴム、クロロプレンゴム及びアクリロニトリル系ゴム等が挙げられる。塗工方法としては、浸漬塗工法、ロール塗工法及びスプレー塗工法などがよい。
【０２５６】
また、表面層２ｄをチューブを被覆することにより設ける場合、具体的な材料としては、ナイロン１２、ＰＦＡ（４フッ化エチレン−パーフルオロアルキルビニルエーテル共重合樹脂）、ＰＶＤＦ（ポリフッ化ビニリデン）、ＦＥＰ（４フッ化エチレン−６フッ化プロピレン共重合樹脂）、更にはポリスチレン系、ポリオレフィン系、ポリ塩化ビニル系、ポリウレタン系、ポリエステル系及びポリアミド系等の熱可塑性エラストマーが挙げられる。
【０２５７】
チューブは熱収縮性チューブであってもよいし、非熱収縮性チューブであってもよい。表面層２ｄにも適度な導電性を持たせるため、カーボンブラック及びカーボングラファイトのような導電性粒子や、導電性酸化チタン、導電性酸化亜鉛及び導電性酸化錫等の導電性金属酸化物等の導電剤が用いられる。
【０２５８】
前記表面層の電気抵抗は、１×１０⁶〜１×１０¹⁴［Ωｃｍ］の範囲であることが好ましい。また、膜厚は、２乃至５００μｍであることが好ましい。より好ましくは、２乃至２５０μｍである。
【０２５９】
抵抗制御層２ｃは帯電部材の抵抗を制御するために設けることが多い。抵抗制御層２ｃの具体的材料としては、ポリアミド樹脂、ポリウレタン樹脂、フッ素樹脂、シリコーン樹脂等の樹脂、さらにはエピクロルヒドリンゴム、ウレタンゴム、クロロプレンゴム及びアクリロニトリル系ゴム等が挙げられる。抵抗制御層２ｃにも抵抗調整を目的として、カーボンブラックやカーボングラファイトのような導電性粒子や、導電性酸化チタン、導電性酸化亜鉛及び導電性酸化錫等の導電性金属酸化物あるいはアルカリ金属塩及びアンモニウム塩等の導電剤を分散することができる。抵抗制御層２ｃもまた塗工あるいはチューブを被覆することによって設ける。
【０２６０】
前記抵抗制御層の電気抵抗は、１×１０⁶〜１×１０¹⁰［Ωｃｍ］の範囲であることが好ましい。
【０２６１】
また、膜厚は、１０乃至１０００μｍであることが好ましい。より好ましくは、１０乃至７５０μｍである。
【０２６２】
本発明における体積抵抗率の測定は、ＪＩＳ Ｋ ６９１１に準じて行ったものである。
【０２６３】
図２において、２ｆは帯電ローラクリーニング部材であり、本例では可撓性を持つクリーニングフィルムである。このクリーニングフィルム２ｆは帯電ローラ２の長手方向に対し平行に配置され且つ同長手方向に対し一定量の往復運動をする支持部材２ｇに一端を固定され、自由端側近傍の面において帯電ローラ２と接触ニップを形成するよう配置されている。支持部材２ｇがプリンタの駆動モーターによりギア列を介して長手方向に対し一定量の往復運動駆動されて帯電ローラ表面層２ｄがクリーニングフィルム２ｆで摺擦される。これにより帯電ローラ表面層２ｄの付着汚染物（微粉トナー、外添剤など）の除去がなされる。
【０２６４】
ｃ）情報書き込み手段
３は帯電処理された感光ドラム１の面に静電潜像を形成する情報書き込み手段としては露光である。ＬＥＤアレイを用いる方法、半導体レーザを用いる方法、液晶シャッタアレイを用いた方などがある。
【０２６５】
本例は半導体レーザを用いたレーザビームスキャナである。画像読み取り装置等のホスト装置からプリンタ側に送られた画像信号に対応して変調されたレーザ光を出力して回転感光ドラム１の一様帯電処理面を露光位置ｂにおいてレーザ走査露光Ｌ（イメージ露光）する。このレーザ走査露光Ｌにより感光ドラム１面のレーザ光で照射されたところの電位が低下することで回転感光ドラム１面には走査露光した画像情報に対応した静電潜像が順次に形成されていく。
【０２６６】
ｄ）現像手段
４は感光ドラム１上の静電潜像に現像剤（トナー）を供給し静電潜像を可視化する現像手段としての現像装置（現像器）であり、本例は二成分磁気ブラシ現像方式の反転現像装置である。
【０２６７】
４ａは現像容器、４ｂは非磁性の現像スリーブであり、この現像スリーブ４ｂはその外周面の一部を外部に露呈させて現像容器４ａ内に回転可能に配設してある。４ｃは非回転に固定して現像スリーブ４ｂ内に挿設したマグネットローラ、４ｄは現像剤コーティングブレード、４ｅは現像容器４ａに収容した二成分現像剤、４ｆは現像容器４ａ内の底部側に配設した現像剤撹拌部材、４ｇはトナーホッパーであり、補給用トナーを収容させてある。
【０２６８】
而して、回転する現像スリーブ４ｂの面に薄層としてカーボン及びグラファイトが分散されたフェノール樹脂がコーティングされ、現像部ｃに搬送された現像剤中のトナー分が現像バイアスによる電界によって感光ドラム１面に静電潜像に対応して選択的に付着することで静電潜像がトナー画像として現像される。本例の場合は感光ドラム１面の露光明部にトナーが付着して静電潜像が反転現像される。
【０２６９】
現像部ｃを通過した現像スリーブ４ｂ上の現像剤薄層は引き続く現像スリーブの回転に伴い現像容器４ａ内の現像剤溜り部に戻される。
【０２７０】
現像容器４ａ内の二成分現像剤４ｅのトナー濃度を所定の略一定範囲内に維持させるために、現像容器４ａ内の二成分現像剤４ｅのトナー濃度が不図示の例えば光学式トナー濃度センサーによって検知され、その検知情報に応じてトナーホッパー４ｇが駆動制御されて、トナーホッパー内のトナーが現像容器４ａ内の二成分現像剤４ｅに補給される。二成分現像剤４ｅに補給されたトナーは撹拌部材４ｆにより撹拌される。
【０２７１】
ｅ）転写手段・定着手段
５は転写装置であり、本例は転写ローラである。この転写ローラ５は感光ドラム１に所定の押圧力をもって圧接させてあり、その圧接ニップ部が転写部ｄである。この転写部ｄに不図示の給紙機構部から所定の制御タイミングにて転写材（被転写部材、記録材）Ｐが給送される。
【０２７２】
転写部ｄに給送された転写材Ｐは回転する感光ドラム１と転写ローラ５の間に挟持されて搬送され、その間、転写ローラ５に電源Ｓ３からトナーの正規帯電極性である負極性とは逆極性である正極性の転写バイアス本例では＋２ｋＶが印加されることで、転写部ｄを挟持搬送されていく転写材Ｐの面に感光ドラム１面側のトナー画像が順次に静電転写されていく。
【０２７３】
転写部ｄを通ってトナー画像の転写を受けた転写材Ｐは回転感光ドラム１面から順次に分離されて定着装置６（例えば熱ローラ定着装置）へ搬送されてトナー画像の定着処理を受けて画像形成物（プリント、コピー）として出力される。
【０２７４】
（２）クリーナレスシステムおよびトナー帯電量制御
本例のプリンタはクリーナレスであり、転写材Ｐに対するトナー画像転写後の感光ドラム１面に若干量残留する転写残トナーを除去する専用のクリーニング装置は具備させていない。転写後の感光ドラム１面上の転写残トナーは引き続く感光ドラム１の回転に伴い帯電部ａ、露光部ｂを通って現像部ｃに持ち運ばれて、現像装置４により現像同時クリーニング（回収）される（クリーナレスシステム）。
【０２７５】
本実施例においては現像装置４の現像スリーブ４ｂは前述したように現像部ｃにおいて、感光ドラム１面の進行方向とは逆方法に回転させており、これは感光ドラム１上の転写版トナーの回収に有利である。
【０２７６】
感光ドラム１面上の転写残トナーは露光部ｂを通るので露光工程はその転写残トナー上からなされるが、転写残トナーの量は少ないため、大きな影響は現れない。
【０２７７】
ただ前述のように、転写残トナーには帯電極性が正規極性のもの、逆極性のもの（反転トナー）、帯電量が少ないものが混在しており、その内の反転トナーや帯電量が少ないトナーが帯電部ａを通過する際に帯電ローラ２に付着することで帯電ローラが許容以上にトナー汚染して帯電不良を生じることになる。
【０２７８】
また、感光ドラム１面上の転写残トナーの現像装置３による現像兼回収を効果的に行なわせるためには、現像部ｃに持ち運ばれる感光ドラム上の転写残トナーの帯電極性が正規極性であり、かつその帯電量が現像装置によって感光ドラムの静電潜像を現像できるトナーの帯電量であることが必要である。反転トナーや帯電量が適切でないトナーについては感光ドラム上から現像装置に除去・回収できず、不良画像の原因となってしまう。
【０２７９】
そこで本実施例においては、転写部ｄよりも感光ドラム回転方向下流側で、帯電部ａよりも感光ドラム回転方向上流側の位置において、転写残トナーの帯電極性を正規極性である負極性に揃えるためのトナー（現像剤）帯電量制御手段７を設けている。
【０２８０】
転写残トナーの帯電極性を正規極性である負極性に揃えることにより、さらに下流に位置する帯電部ａで、該転写残トナーの上から感光ドラム１面上を帯電処理する際に、感光ドラム１への鏡映力が大きくし、転写残トナーの帯電ローラ２への付着を防止するのである。
【０２８１】
次に現像工程における転写残トナーの回収について述べる。
【０２８２】
現像装置４は上述したとおりで、現像を行う際に転写残トナーを清掃するクリーナレス方式である。
【０２８３】
感光ドラム１上の転写残トナーが現像装置４に回収されるためのトナー帯電量は、前記現像剤帯電量制御手段で帯電処理されたときの帯電量の絶対値よりも小さい絶対値の帯電量にすることが必要である。これはいわゆる除電であり、転写残トナーの帯電量が高いとドラムとの親和力の方が勝り、現像装置４に回収されなくなり、画像欠陥を生じることによる。
【０２８４】
しかしながら、上述したように帯電ローラ２へのトナー付着を防止するために、トナー帯電量制御手段７によって負極性に大きく帯電された転写残トナーを、現像装置４において回収させるためには、除電を行う必要がある。その除電は帯電部ａでなされる。即ち、帯電ローラ２には前記したように１０００Ｈｚ、１４００Ｖの交流電圧が印加されていることにより、転写残トナーは交流除電されるのである。また、帯電ローラ２への印加交流電圧の調整により帯電部ａを通過後のトナー帯電量を交流除電で調整することができる。現像工程においては、トナーが現像されるべきではない感光ドラム１上の転写残トナーは、上記の理由で現像装置４に回収される。
【０２８５】
かくして、転写部ｄから帯電部ａへ持ち運ばれる感光ドラム１上の転写残トナーのトリボをトナー帯電量制御手段７で正規極性である負極性に揃えて帯電処理することで転写残トナーの帯電ローラ２への付着を防止しつつ、帯電ローラ２で感光ドラム１を所定の電位に帯電すると同時に、上記のトナー帯電量制御手段７で正規極性である負極性に帯電処理された転写残トナーの帯電量を、現像装置４によって感光ドラムの静電潜像を現像できる適切な帯電量に制御することで現像装置での転写残トナーの回収も効率的になされるもので、これにより、帯電不良や不良画像がなく、しかもクリーナレスシステムのメリットを生かした画像形成装置を提供できる。
【０２８６】
【実施例】
本発明を以下に実施例を示すことでより具体的に説明するが、これは本発明になんら限定するものではない。
【０２８７】
以下にキャリアの製造方法について説明する。
【０２８８】
（磁性キャリアの製造例１）
水媒体中にフェノール／ホルムアルデヒドモノマー（５０：５０）を混合分散した後、モノマー重量に対して、チタンカップリング剤で表面処理した０．２４μｍのマグネタイト粒子７００部、０．５９μｍのヘマタイト粒子３００部を均一に分散させ、アンモニアを適宜添加しつつモノマーを重合させ、磁性粒子内包球状磁性樹脂キャリア芯材１（平均粒径３２μｍ，飽和磁化３７Ａｍ²／ｋｇ）を得た。
【０２８９】
一方、トルエン２０部，ブタノール２０部，水２０部，氷４０部を四つ口フラスコにとり、撹拌しながらＣＨ₃ＳｉＣｌ₃１５モルと（ＣＨ₃）₂ＳｉＣｌ₂１０モルとの混合物４０部を加え、更に３０分間撹拌した後、６０℃で１時間縮合反応を行った。その後シロキサンを水で十分に洗浄し、トルエン−メチルエチルケトン−ブタノール混合溶媒に溶解して固型分１０％のシリコーンワニスを調製した。
【０２９０】
このシリコーンワニスにシロキサン固型分１００部に対して２．０部のイオン交換水および２．０部の下記硬化剤（２）、１．０部の下記アミノシランカップリング剤（１１）および、５．０部の下部シランカップリング剤（１８）を同時添加し、キャリア被覆溶液Ｉを作製した。この溶液Ｉを塗布機（岡田精工社製：スピラコータ）により、前述のキャリア芯材１００部に、樹脂コート量が１部となるように塗布し、コートキャリア１を得た。
【０２９１】
このキャリアは５０％粒径が３４μｍであり、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が３．２体積％であり、ＳＦ−１の値は１０９であった。
【０２９２】
さらに比抵抗が、８×１０¹³Ωｃｍであり、飽和磁化が４１Ａｍ²／ｋｇであった。
【０２９３】
【化６】

【０２９４】
（磁性キャリアの製造例２）
ＭｇＯ１５部，ＭｎＯ１０部，Ｆｅ₂Ｏ₃７５部を使用して微粒化した後、水を添加し造粒した後、１２００℃にて焼成し、体積平均による５０％径が３２μｍで、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が８．４体積％のフェライトキャリア芯材を得た。
【０２９５】
上記芯材に、製造例１と同様に樹脂コートを行い、コートキャリア４を得た。
【０２９６】
このキャリアのＳＦ−１の値は１２６であった。
【０２９７】
さらに比抵抗が、４×１０¹²Ωｃｍであり、飽和磁化が、５６Ａｍ²／ｋｇであった。
【０２９８】
次に、帯電ローラの製造方法を説明する。
【０２９９】
（帯電ローラーの製造例１）
ＥＰＤＭ１００質量部に対し、導電性カーボンブラック３９質量部、パラフィンオイル５１質量部と発泡剤、架橋剤及びその他の配合剤を適量添加、混練し、導電性コンパウンド１を作製した。次に、直径６ｍｍのステンレス製芯金に前記コンパウンドを加硫成形した後、外径を研磨し、厚さ３ｍｍの発泡体である弾性層１を作製した。
【０３００】
次に、エーテル系熱可塑性ウレタンエラストマー（アスカーＣ硬度；６２）１０質量部に導電性カーボンブラック１５．５質量部を配合し、加圧式ニーダーを用い１８２℃で９分間溶融混練した。更に冷却後、粉砕機にて粉砕した後、単軸押出機を用いてペレット化した。
【０３０１】
このペレットを押出機を用いて、内径が１０．５［ｍｍ］、肉厚５００［μｍ］のシームレスチューブを得た。このチューブを以下チューブＡと呼称する。
【０３０２】
更に、同じペレットを用いて、熱プレスにより直径５ｍｍ、厚み３ｍｍの円板状シートを作製し、前記弾性層１の軟化剤であるパラフィンオイルに７日間浸漬放置した。このシートで放置前後の重量変化率及び体積抵抗率を測定したところ、重量変化率は０．０３％であり、体積抵抗率は放置前で１．９×１０⁶Ωｃｍ、放置後で２．０×１０⁶Ωｃｍと殆ど変化はなかった。
【０３０３】
これとは別に、エチレンブチレンゴム分子鎖の片端にポリスチレン分子鎖、もう逆端にオレフィン結晶が共有結合で結び付いた熱可塑性エラストマー（アスカーＣ硬度；６２）１００質量部の導電性カーボンブラック１４質量部を配合し、加圧式ニーダーを用い２００℃で１０分間溶融混練した。更に冷却後、粉砕機にて粉砕した後、単軸押出機を用いてペレット化した。更に、このペレットを押出機を用いて、内径が１１．５［ｍｍ］、肉厚２００［μｍ］のシームレスチューブを得た。このチューブを以下チューブＢと呼称する。
【０３０４】
続いて、チューブＡにエアーを吹き込み外径を拡大しつつ、弾性層１を挿入してチューブを被覆した後、チューブＢをその外側に同様の方法で被覆して帯電ローラー１を得た。
【０３０５】
得られた帯電ローラー１の各特性は以下の通りであった。
【０３０６】
電気抵抗値；
低温低湿環境（温度１５℃、湿度１０％、以下Ｌ／Ｌ環境） １．２ＭΩ
高温高湿環境（温度３２．５℃、湿度８０％、以下Ｈ／Ｈ環境）１．０ＭΩ
表面硬度 ；６２度（アスカーＣ）
【０３０７】
電気抵抗値は、帯電ローラーの外周に１０ｍｍ幅のアルミニウム箔を密着させて巻き付け、芯金とアルミ箔間に直流電圧２５０Ｖを印加し、抵抗計ＨＩＯＫＩ３１１９ ＤＩＧＩＴＡＬ ＭΩ ＨＩＴＥＳＴＥＲ（日置電機製）を使用して測定した値である。
【０３０８】
表面硬度（アスカーＣ）は、アスカーＣゴム硬度計（高分子計器（株）社製）を用いて行い、５点平均で数値を求めたものである。なお、測定は片側５００ｇ荷重で測定する。
【０３０９】
（シリカ微粉体（Ａ）の製造例１）
下記の如く、乾式シリカの製造方法にてシリカを作製した。支燃性ガス供給管を開いて酸素ガスをバーナーに供給し、着火用バーナーに点火した後、可燃性ガス供給管を開いて水素ガスをバーナーに供給して火炎を形成し、これに四塩化珪素を蒸発器にてガス化して供給し、火炎加水分解反応を行わせ、生成したシリカ粉末を回収した。得られたシリカ微粉末１００質量部を用い、これをミキサーに入れ、窒素雰囲気下、撹拌しながら、５０ｍｍ²／ｓのジメチルシリコーンオイル２０質量部を滴下し、３００℃で１時間加熱撹拌した後に冷却しシリカ微粉体（Ａ−１）を作製した。表１に記す。
【０３１０】
（シリカ微粉体（Ａ）の製造例２〜１１）
原料の四塩化珪素ガス量、水素ガスおよび酸素ガスの量、火炎中のシリカ濃度と滞留時間を調整しシリカ原体を得た後、各種疎水化処理を施し、シリカ微粉体（Ａ−２）〜（Ａ−１１）まで製造した。表１に記す。
【０３１１】
（シリカ微粉体（Ｂ）の製造例１〜９）
シリカ微粉体（Ａ）と同様に、原料の四塩化珪素ガス量、水素ガスおよび酸素ガスの量、火炎中のシリカ濃度と滞留時間を調整しシリカ原体を得た後、各種疎水化処理を施し、シリカ微粉体（Ｂ−１）〜（Ｂ−９）まで製造した。表２に示す。
【０３１２】
【表１】

【０３１３】
【表２】

【０３１４】
以下に、トナーの製造方法について説明する。
【０３１５】
（トナーの製造例１）
本発明に用いるシアントナーは、次の如くして調製した。高速撹拌装置ＴＫ−ホモミキサーを備えた２リットル用四つ口フラスコ中に、イオン交換水９１０質量部とポリビニルアルコール１質量部を添加し回転数を１２０００回転に調整し、６０℃に加温せしめ分散剤系とした。
【０３１６】
一方、分散質系は、
スチレン単量体 １６４質量部
ｎ−ブチルアクリレート単量体 ３６質量部
フタロシアニン顔料 ９質量部
（Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３）
飽和ポリエステル樹脂 １０質量部
（ビスフェノールＡとテレフタル酸との重縮合物、酸価１０、
ガラス転移点７０℃）
ｔ−ブチルサリチル酸金属塩 ４質量部
ジビニルベンゼン ０．１５質量部
低軟化点物質 ３０質量部
（エステルワックスＭｗ＝１２００，Ｍｎ＝７５０，Ｍｗ／Ｍｎ＝１．６）
上記混合物をアトライターを用い３時間分散させた後、重合開始剤である２，２’−アゾビス（２，４−ジメチルバレロニトリル）４質量部を添加した分散物を、上記分散媒中に投入し回転数を維持しつつ１０分間造粒した。その後高速撹拌器からプロペラ撹拌羽根に撹拌器を代え内温を６２℃に昇温させ５０回転で重合を１０時間継続した。
【０３１７】
重合終了後スラリーを冷却し、水洗、乾燥をしてシアン粒子を得た。得られたシアン粒子１００質量部に対し、粘度５０ｍｍ²／ｓのポリジメチルシロキサンにより疎水化処理を行い、処理後に解砕処理および分級処理を行い粒度調整を行ったシリカ微粉末（Ａ−１）（平均１次粒径２２ｎｍ、ＢＥＴ８２ｍ²／ｇ）を０．５質量部、同じく粘度５０ｍｍ²／ｓのポリジメチルシロキサンにより疎水化処理を行ったシリカ微粉末（Ｂ−１）（平均１次粒径９ｎｍ、ＢＥＴ１４０ｍ²／ｇ）を０．５質量部、そしてイソプロピルトリメトキシシランにより疎水化処理を行ったアルミナ微粉末（平均１次粒径４０ｎｍ、ＢＥＴ１１０ｍ²／ｇ）を０．５質量部を加え、三井鉱山社製ヘンシェルミキサーを用いて均一拡散しシアントナー（１）を得た。
【０３１８】
得られたシアン粒子をコールターカウンターにより粒度分布を測定したところ、体積平均径は６．１μｍであった。トナーの構成表を表３に示す。
【０３１９】
＜トナーの比較製造例１＞
トナーの製造例１において、水系媒体の製造時における０．１Ｍ−Ｎａ₃ＰＯ₄水溶液の使用量を６００部、重合性単量体組成物の造粒時におけるクレアミキサーの回転数を１４，０００ｒｐｍ、分級時の多段分割式分級機の分級条件をそれぞれ変更し、外添剤の添加量を総量で１．８質量部とした以外は上記製造例１と同様の方法を用いて、質量平均粒径３．３μｍの比較用シアントナー（比較トナー１）を得た。
【０３２０】
＜トナーの比較製造例２＞
トナーの製造例１において、水系媒体の製造時における０．１Ｍ−Ｎａ₃ＰＯ₄水溶液の使用量を１９０部、重合性単量体組成物の造粒時におけるクレアミキサーの回転数を４３００ｒｐｍ、分級時の多段分割式分級機の分級条件をそれぞれ変更し、外添剤の添加量を総量で１．４質量部とした以外は上記製造例１と同様の方法を用いて、質量平均粒径１０．６μｍの比較用シアントナー（比較トナー２）を得た。
【０３２１】
＜トナーの製造例２＞
トナーの製造例１において、水系媒体の製造時における０．１Ｍ−Ｎａ₃ＰＯ₄水溶液の使用量を５３０部、重合性単量体組成物の造粒時におけるクレアミキサーの回転数を１２０００ｒｐｍ、分級時の多段分割式分級機の分級条件をそれぞれ変更し、外添剤の添加量を総量で１．５質量部とした以外は上記製造例１と同様の方法を用いて、質量平均粒径４．２μｍのシアントナー（トナー２）を得た。
【０３２２】
＜トナーの製造例３＞
トナーの製造例１において、水系媒体の製造時における０．１Ｍ−Ｎａ₃ＰＯ₄水溶液の使用量を２８０部、重合性単量体組成物の造粒時におけるクレアミキサーの回転数を５５５０ｒｐｍ、分級時の多段分割式分級機の分級条件をそれぞれ変更し、外添剤の添加量を総量で１．５質量部とした以外は上記製造例１と同様の方法を用いて、質量平均粒径９．３μｍのシアントナー（トナー３）を得た。
【０３２３】
＜トナーの製造例４乃至１８、２１＞
製造例１におけるシアン粒子に対して、それぞれ表１及び２に示す物性を有するように、疎水化処理方法、解砕方法、および分級方法等の製造方法を変えて得られた微粉末を表３に示す構成で外添することによりシアントナー（４）乃至（１８）を得た。
【０３２４】
＜トナーの比較製造例３乃至１１＞
製造例１におけるシアン粒子に対して、それぞれ表１及び２に示す物性を有するように、疎水化処理方法、解砕方法、および分級方法等の製造方法を変えて得られた微粉末を外添することにより比較シアントナー（３）乃至（１１）を得た。
【０３２５】
＜トナーの製造例１９＞
スチレン−２−エチルヘキシルアクリレート−ジビニルベンゼン共重合体
（ガラス転移点６５℃） １００質量部
フタロシアニン顔料 ７質量部
（Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３）
飽和ポリエステル樹脂 ５質量部
（ビスフェノールＡとテレフタル酸との重縮合物、酸価１０
ガラス転移点６５℃）
ジアルキルサリチル酸金属化合物 １質量部
低軟化点物質 ８質量部
（パラフィンワックスＭｗ＝１２００，Ｍｎ＝７５０，Ｍｗ／Ｍｎ＝１．６）
上記混合物をヘンシェルミキサーで予備混合し、二軸押出混練機により温度１３０℃にて溶融混練し、冷却後、ハンマーミルを用いて粗粉砕し、次いでエアージェット方式による微粉砕機で粉砕した。これを分級してシアン粒子を得た。
【０３２６】
この時、粒子の平均円形度は０．９４０であった。
【０３２７】
このシアン粒子に対し、製造例１と同様に外添を行いシアントナー（１９）を得た。
【０３２８】
＜トナーの製造例２０＞
製造例１９におけるシアン粒子に対して、羽根が回転して機械式に処理を行う形式の表面処理装置を用いて球形化処理を行いシアン粒子を得た。
【０３２９】
この時、粒子の平均円形度は０．９５５であった。
【０３３０】
このシアン粒子に対し、製造例１と同様に外添を行いシアントナー（２０）を得た。
【０３３１】
＜トナーの製造例２２乃至２４＞
着色剤としてマゼンタ着色剤（Ｃ．Ｉ．ピグメントレッド１２２）、イエロー着色剤（Ｃ．Ｉ．ピグメントイエロー９３）、またはブラック着色剤（グラフトカーボンブラック）を使用することを除いて、製造例１と同様にしてマゼンタトナー（２２）、イエロートナー（２３）およびブラックトナー（２４）を調製した。
【０３３２】
【表３】

【０３３３】
【表４】

【０３３４】
（実施例１）
シアントナー１とコートキャリア１とをトナー濃度８％で混合してシアン二成分系現像剤１を作製した。
【０３３５】
次に、市販の複写機ＣＰ２１５０（キヤノン製）の現像装置を図２に示す如く改造し、現像スリーブとしてはφ１６ｍｍのＳＵＳスリーブをサンドブラスト処理によって表面形状をＲｚ＝９．０に調整したものを使用した。
【０３３６】
また本例においてはトナー帯電制御手段を装備しており、印加電圧は−８００Ｖとした。
【０３３７】
帯電部材としては帯電ローラー１を用いている。この帯電ロ一ラは、感光ドラム方向に付勢して感光ドラムの表面に対して所定の押圧力をもって圧接させており、感光ドラムの回転に従動して回転する。感光ドラムと帯電ローラとの圧接部が帯電部（帯電ニップ部）である。また、ポリイミドからなる中間転写ベルトを装着させ、２次転写用複写機に改造した。
【０３３８】
さらに本例において、帯電ローラに対する帯電バイアス電圧は直流電圧（Ｖｄｃ）と交流電圧（Ｖａｃ）とを重畳した振動電圧である。
【０３３９】
より具体的には、
直流電圧；−５００Ｖ
交流電圧；周波数ｆ１０００Ｈｚ、ピーク間電圧Ｖｐｐ８００Ｖ、正弦波とを重畳した振動電圧であり、感光ドラム１の周面は−５００Ｖ（暗電位Ｖｄ）に一様に接触帯電処理される。
【０３４０】
クリーニングユニットを取り外し、現像コントラスト２５０Ｖ、カブリとの反転コントラスト−１５０Ｖに設定し、非連続の交流電界を有する現像バイアスを印加し前述のシアン二成分系現像剤１を使用し高温高湿環境（３２．５℃／８５％ＲＨ）及び低温低湿（１５℃／１０％ＲＨ）下で、画像面積比率１０％のオリジナル原稿を用いて、５万枚の連続複写を行った画出しを行った。結果を表５、表６に示す。
【０３４１】
［現像性評価方法］
（画像濃度変化）
画像濃度はカラー反射濃度計（例えばＣｏｌｏｒｒｅｆｌｅｃｔｉｏｎ ｄｅｎｓｉｔｏｍｅｔｅｒ Ｘ−ＲＩＴＥ ４０４Ａｍａｎｕｆａｃｔｕｒｅｄ ｂｙ Ｘ−Ｒｉｔｅ Ｃｏ．）で測定する。
【０３４２】
初期濃度と５万枚耐久後の濃度の差で評価する。
Ａ：０．０５以下
Ｂ：０．０５を超え０．１以下
Ｃ：０．１を超え０．２以下
Ｄ：０．２を超え０．３以下
Ｅ：０．３を超え０．４以下
Ｆ：０．４を超え０．５以下
Ｇ：０．５を超える
【０３４３】
（カブリの測定）
カブリの測定は、ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳ（東京電色社製）を用い測定し、下記式により算出した。カブリ値は少ない方が良好である。

Ａ：０．６以下
Ｂ：０．６を超え１．１以下
Ｃ：１．１を超え１．６以下
Ｄ：１．６を超え２．０以下
Ｅ：２．０を超え３．０以下
Ｆ：３．０を超え４．０以下
Ｇ：４．０を超える
【０３４４】
（帯電量変化）
帯電量変化は、現像容器内の現像剤の耐久初期及び５万枚通紙後の帯電量値の変化量を下記評価基準に基づいて評価した。
Ａ：変化量が５％以下
Ｂ：変化量が５％を超え１０％以下
Ｃ：変化量が１０％を超え１５％以下
Ｄ：変化量が１５％を超え２０％以下
Ｅ：変化量が２０％を超え２５％以下
Ｆ：変化量が２５％を超え３０％以下
Ｇ：変化量が３％を超える
【０３４５】
（帯電ローラ汚れ）
帯電ローラ汚れは、ローラ表面を目視（５０倍のルーペも使用）で観察し、さらに画像欠陥を観察し、下記評価基準に基づいて評価した。
Ａ；ルーペ観察においてローラ表面、画像ともに欠陥は全く認められない。
Ｂ；耐久後半、ルーペ観察においてのみローラ表面に汚れが若干認められるが、目視においては確認できず、画像にも現れない。
Ｃ；耐久後半、ルーペ観察においてローラ表面に汚れが若干認められ、目視においても認められるレベルであるが、画像には現れない。。
Ｄ；耐久後半、ルーペ観察及び目視においてローラ表面に汚れが若干認められ、画像にも若干ムラが認められ、実使用上も問題となるレベル。
Ｅ：耐久後半、ルーペ観察及び目視においてローラ表面に汚れが多数認められ、画像にもかなりムラが認められ、実使用上受け入れられない。
Ｆ：耐久後半、ルーペ観察するまでもなく目視においてローラ表面に汚れが認められ、画像にも顕著にムラが認められ、使用に耐えない。
Ｇ：耐久前半から、ローラーは汚れ、画像もムラが多数で使用に完全に耐えない。
【０３４６】
（転写効率）
転写効率は、５万枚通紙後の現像剤を図６に示す画像形成装置を用い、Ｎ／Ｎ条件下、感光体に現像したトナー質量に対する紙上に転写したトナー質量の割合を下記評価基準に基づいて評価した。
Ａ：９５％以上。
Ｂ：９０％を超え９５％未満。
Ｃ：８０％を超え９０％未満。
Ｄ：７０％を超え８０％未満。
Ｅ：６０％を超え７０％未満。
Ｆ：５０％を超え６０％未満。
Ｇ：５０％以下。
【０３４７】
（ベタ均一性）
得られた転写紙上のベタ部画像は５点の濃度の最大値と最小値ので下記評価基準に基づいて評価した。
Ａ；０．０５以下
Ｂ：０．０５を超え０．１以下
Ｃ：０．１を超え０．１５以下
Ｄ：０．１５を超え０．２以下
Ｅ：０．２を超え０．２５以下
Ｆ：０．２５を超え０．３以下
Ｇ：０．３を超える
【０３４８】
（ドラム融着）
ドラム融着は、ドラム表面を目視で観察し、さらに画像欠陥を観察し、下記評価基準に基づいて評価した。
Ａ：ドラム融着が全くない
Ｂ：ドラム融着がほとんどない
Ｃ：若干ドラム融着があるが実使用上全く問題ないレベル
Ｄ：耐久後半にドラム融着あり、画像を汚染する場合あり
Ｅ：耐久前半からドラム融着あり、画像を汚染する場合あり
Ｆ：顕著なドラム融着が生じている
Ｇ：ドラム融着が激しく、実使用上耐えない。
【０３４９】
（ラインのり量／ベタのり量比）
紙上に転写された未定着画像の単位面積あたりののり量から算出する。画像濃度１．４となるベタ画像のり量と、同一現像条件で得られた０．５ｍｍ幅の縦ライン（転写材排紙方向と平行の方向）ののり量を測定し、下記式により求める。
ラインのり量（ｍｇ／ｃｍ²）／べた画像のり量（ｍｇ／ｃｍ²）
【０３５０】
（画質）
Ｎ／Ｌ及びＨ／Ｈ環境下での耐久試験において、オリジナル原稿を基準にして、階調性、ハイライト均一性及び細線再現性、画像濃淡について目視により下記の評価項目に従い総合的に評価した。
Ａ：かなり高い画質である
Ｂ：良好な画質である
Ｃ：ぎりぎり許容できるレベルの画質である
Ｄ：画質が若干悪く、厳しいユーザーにはクレームとなるレベル
Ｅ：悪いレベルであり、実使用上問題。
Ｆ：かなり悪く、使用に耐えない。
Ｇ：文字として認識できないほど悪い
【０３５１】
（トナー飛散）
Ｈ／Ｈ環境で３万枚画出しした後のマシン内トナー飛散量を目視によって、以下の基準で総合的に評価した。
Ａ：トナー飛散が全くない
Ｂ：トナー飛散がほとんどない
Ｃ：若干トナー飛散があるが実使用上全く問題ないレベル
Ｄ：トナー飛散あり、耐久後半に画像を汚染する場合あり
Ｅ：トナー飛散あり、耐久前半から画像を汚染する場合あり
Ｆ：顕著なトナー飛散が生じる
Ｇ：トナーとキャリアが分離した状態でトナー飛散が激しく、実使用上耐えない
【０３５２】
（９）定着性評価
コピー濃度が最大のものと、濃度が０．５である未定着画像をＣＰ２１５０機により得る。これをＣＰ２１５０の外部駆動型の定着器を用いて、１６５℃設定で定着テストを行う。評価は以下の様に行う。
【０３５３】
（ａ）ベタ黒部（最大画像濃度）は、定着後の画像濃度（Ｄｉ ｍａｘ）を測定し、次に２枚のＬｅｎｚ Ｃｌｅａｎｉｎｇ Ｐａｐｅｒ“ｄａｓｐｅｒ（Ｒ）”（Ｏｚｕ Ｐａｐｅｒ Ｃｏ．，Ｌｔｄ．）上に２００ｇの加重を与え、画像上を１０回摺擦し、摺擦後の画像濃度Ｄｍ ｍａｘを測定する。下記摺擦濃度低下率ｄｖ ｍａｘの値をもって、下記判断とする。
評価ランク
Ａ：濃度低下率０％以上２．５％未満
Ｂ：２．５％以上５％未満
Ｃ：５％以上１０％未満
Ｄ：１０％以上２０％未満
Ｅ：２０％以上３０％未満
Ｆ：３０％以上５０％未満
Ｇ：５０％以上
【０３５４】
（実施例２乃至２４、および比較例１乃至１１）
実施例１において、表５、６に示すような構成で同様の試験を行った。その結果を示す。
【０３５５】
（実施例２５）
２成分フルカラーシステムで画だし評価を行った際の、シアントナーの画像評価結果を示す。
【０３５６】
（実施例２６）
キヤノン製ＬＢＰ ＣＰ６６０で８０００枚の画像評価を行った際のシアントナーの評価結果を示す。
【０３５７】
【表５】

【０３５８】
【表６】

【０３５９】
【発明の効果】
本発明のトナーにおいては、中間転写体を用いた２次転写システムにおいて、トナー表面に外添処理を行う外添剤の粒径を所定の分布とし、さらにその外添剤を疎水化処理することにより，部材や感光ドラムを汚染したり、傷つけたりすることが少なく、多数枚の連続プリントを行っても、画像濃度が安定し、カブリのない耐久安定性にすぐれた画像形成方法が得られる。
【０３６０】
更に、表面硬度を規定した導電性弾性層を有する帯電ローラーを用いた画像形成装置において、多数枚の連続プリントを行っても、画像濃度が安定し、カブリのない耐久安定性にすぐれたクリーナレス方式の画像形成方法が得られる。
【図面の簡単な説明】
【図１】本発明に適用されうる画像形成装置の一例を示す概略説明図である。
【図２】本発明に適用されうる帯電ローラーの一例を示す概略説明図である。
【図３】本発明に適用されうる電子写真感光体の一例を示す概略説明図である。
【図４】本発明に適用されうる電子写真感光体の他の一例を示す概略説明図である。
【図５】本発明に適用されうる電子写真感光体の他の一例を示す概略説明図である。
【図６】本発明に適用されうる画像形成方法を実施可能なさらに別の画像形成装置を示す概略説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method having an intermediate transfer member in an image forming apparatus used for electrophotography or electrostatic printing, and a toner that can be suitably used for the image forming method.
[0002]
[Prior art]
Conventionally, many methods are known as electrophotographic methods. In general, a photoconductive substance is used, and an electrostatic charge latent image is formed on the photoconductor by various means, and then the latent image is developed with toner to form a toner image. After the toner image is transferred to the transfer material, the toner image is fixed on the transfer material by heat, pressure, heat and pressure, etc. to obtain a copy or printed matter. Toner particles that are not transferred onto the transfer material but remain on the photoconductor are removed from the photoconductor by a cleaning process.
[0003]
In recent years, there is no end to the user's request to stably output higher quality images. In order to satisfy this requirement, in the process of forming an electrostatic latent image on a photoconductor, a technique for exposing the photoconductor using a small-diameter laser beam or the like has been developed, and the electrostatic latent image has become finer. Along with this, in order to develop the electrostatic latent image faithfully and obtain a higher quality output, the diameter of the toner has been reduced. In recent years, with the explosive spread of digital cameras, an increasing number of users output a large number of photographic images having a high printing rate. On the other hand, as an output image in an office, the output frequency of a table, a graph or the like with a low printing rate is high.
[0004]
Reducing the average particle diameter of the toner is an effective means for improving the granularity and character reproducibility among image quality characteristics, but it is stable from high printing to low printing as described above. In terms of providing high image quality, the hurdle is high. In particular, there are problems to be solved in fogging and toner scattering in the latter half of the durability due to the rising characteristics of toner charging during high-printing printing and the deterioration of the external additive of the toner during low-printing printing.
[0005]
In recent years, an intermediate transfer system using an intermediate transfer belt or the like has become the mainstream in order to provide a machine that can handle various materials such as various types of cardboard, transparency, and postcards. When a small particle size toner is applied to this intermediate transfer system, it is very difficult to maintain high transferability.
[0006]
When the particle size of the toner is reduced, the cohesiveness between the toner particles increases, so that it is difficult to receive good charge application from the charge application member. For this reason, attempts have been made to obtain good developability and transferability by providing uniform and high charging properties by adding small particles of inorganic fine particles to the toner.
[0007]
However, the toner to which such small particle size inorganic fine particles are externally added is, for example, stress with a carrier when used as a two-component developer, developer coating blade when used as a one-component developer The toner that has been used for a long time due to stress from the developer supply roller, the inner wall of the developing device, the stirring blades, or the collision of the toners, etc. will be in a state where small-sized inorganic fine particles are embedded in the surface, and stable developability In addition, it is difficult to provide transferability.
[0008]
In order to reduce the burying of the small particle size inorganic fine particles, as disclosed in Patent Documents 1 to 5, a method of using the large particle size inorganic fine particles in combination is effective.
[0009]
The addition of large-sized inorganic fine particles produces a so-called spacer effect, and the toner surface to which the small-sized inorganic fine particles adhere is the carrier, developer coating blade, developer supply roller, developing device inner wall, stirring blade, other toner, etc. Prevent direct contact and reduce stress. Thereby, the embedding of the small particle size inorganic fine particles is suppressed, and the life of the toner is extended.
[0010]
Furthermore, in order to connect this spacer effect, it is preferable to use silica as the large particle size inorganic fine particles. This is due to the following reasons. Large particle size inorganic fine particles have relatively weak electrostatic adhesion to the toner surface compared to small particle size inorganic fine particles. For this reason, the large particle size inorganic fine particles are easily released from the toner surface, and are consumed and reduced by development or the like, and the spacer effect tends not to last for a long time. Here, since silica has a large charge amount among inorganic powders and a large adhesion force to the toner surface, release is suppressed and a spacer effect can be connected.
[0011]
However, as described above, a toner obtained by externally adding a small particle size inorganic fine particle and a large particle size silica to the toner becomes too charged in a low-humidity environment, and is likely to cause so-called charge-up. Inferior aspects are seen.
[0012]
On the other hand, Patent Document 6 proposes a toner that uses 15 to 20 nm hydrophobic silica and 13 nm or less hydrophobic silica as external additives. In this document, even when an image with a high printing rate is printed, there is an effect of increasing the toner charging speed. On the contrary, when an image with a low printing rate is printed, the external additive on the toner is the toner. In order to suppress the deterioration of the external additive such as being buried or released, there are some problems.
[0013]
In addition, the particle diameter, shape, and charging characteristics of the inorganic fine particles to be added are greatly involved in cleaning and fusing of the photoreceptor. In particular, when an external additive having a small particle size is used to increase fluidity and an externally charged additive is used, the cleaning property is deteriorated. On the other hand, when too large aggregated inorganic fine particles are added, image defects such as fusion are caused.
[0014]
In other words, in order to maintain good developability, transferability, cleaning properties, and photoreceptor filming characteristics, it is necessary to add primary and secondary particle diameters, as well as inorganic fine particles with controlled charging characteristics. .
[0015]
Conventionally, means such as blade cleaning, fur brush cleaning, roller cleaning and the like have been used for the above-described photoreceptor cleaning process. The means mechanically scrapes off the transfer residual toner on the photoconductor or stops it to collect the transfer residual toner in a waste toner container. Therefore, problems are likely to occur due to the members constituting such means being pressed against the surface of the photoreceptor. For example, the surface of the photoreceptor is worn by strongly pressing the cleaning member.
[0016]
Furthermore, since the cleaning device is provided, the entire apparatus is inevitably enlarged, which has become a bottleneck when aiming to make the apparatus compact.
[0017]
On the other hand, from the viewpoint of ecology, a system without waste toner is awaited.
[0018]
For example, Patent Document 7 proposes an image forming apparatus that employs a technique called simultaneous development cleaning or cleaner-less. In the image forming apparatus, one image is formed per one rotation of the photoreceptor so that the influence of the transfer residual toner does not appear on the same image. In Patent Documents 8 to 11, a method in which a transfer residual toner is scattered on a photosensitive member by a scattering member and non-patterned, so that even when the same surface of the photosensitive member is used a plurality of times for one image, it is difficult to be manifested on the image. Has proposed.
[0019]
When a voltage is applied to a member for non-patterning residual toner, it is a cleaner-less system, but it is difficult to simplify and compact the entire apparatus.
[0020]
Patent Document 12 proposes to obtain stable charging characteristics by using a spherical toner and a spherical carrier in a cleanerless electrophotographic printing method. No mention is made of toner physical properties, particularly external additives present on the surface.
[0021]
Patent Document 13 proposes to obtain stable charging characteristics by making the resistance value and the charge amount of the toner appropriate in the cleanerless electrophotographic printing method. There is no mention of existing external additives.
[0022]
In addition, various cleaner-less electrophotographic printing systems have been proposed in Patent Documents 14 to 17 and the like, but a preferred embodiment that matches the cleaner-less system of an external toner additive is not mentioned.
[0023]
Furthermore, the user's demand for high image quality is strong, and from this point of view, the physical properties of the toner, particularly the form of the external additive present on the surface, is important. Toners having excellent development stability have been proposed. However, this publication also has some problems in providing images stably for a long time in various environments.
[0024]
In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors, and in particular, a functionally separated type in which a charge generation layer and a charge transport layer are laminated has been put into practical use. Installed in facsimile machines. As charging means in such an electrophotographic apparatus, means utilizing corona discharge has been used, but a large amount of ozone is generated. Further, from the viewpoint of image quality, the charged wire is contaminated by the scattered toner and the discharge product, so that a streak image is easily generated corresponding to the portion.
[0025]
As a technique for solving such problems, a charging member such as a roller or a blade is brought into contact with the surface of the photosensitive member to form a narrow space near the contact portion, which can be interpreted by the so-called Paschen's law. A charging method has been developed that suppresses ozone generation as much as possible by forming a discharge. Among these, a roller charging method using a charging roller as a charging member is particularly preferably used from the viewpoint of charging stability and image quality.
[0026]
Since this charging is performed by discharging from the charging member to the member to be charged, charging is started by applying a voltage higher than a certain threshold voltage. For example, when the charging roller is brought into contact with a photoconductor containing an organic photoconductive material having a thickness of about 25 μm, the surface potential of the photoconductor increases when a voltage of about 640 V or more is applied. Thereafter, the photosensitive member surface potential increases linearly with a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as the charging start voltage Vth. That is, in order to obtain the photoreceptor surface potential Vd, the charging roller needs a DC voltage higher than that required, that is, Vd + Vth. Furthermore, since the resistance value of the charging roller fluctuates due to environmental fluctuations or the like, it is difficult to set the potential of the photosensitive member to a desired value.
[0027]
For this reason, as disclosed in Patent Document 19 in order to make the different charging uniform, a contact voltage is obtained by superimposing a DC voltage corresponding to a desired Vd on an AC voltage having a peak-to-peak voltage of 2 × Vth or more. A DC + AC charging method applied to the roller is used. This is for the purpose of leveling the potential due to AC, and the potential of the charged object converges to Vd, which is the center of the peak of the AC voltage, and is not easily affected by disturbances such as environmental fluctuations.
[0028]
However, even in such a charging method, the essential charging mechanism uses a discharge phenomenon from the charging member to the photoconductor, so that the voltage required for charging is the surface of the photoconductor as described above. A value greater than the potential is required. In addition, when an AC voltage is applied, vibration and noise (hereinafter referred to as AC charging sound) of the charging member and the photosensitive member due to the electric field of the AC voltage, and deterioration of the photosensitive member surface due to discharge become remarkable. It was a new problem.
[0029]
Patent Document 20 proposes to use secondary particles obtained by fusing primary polymer particles as a toner, and Patent Document 21 proposes to use a polymerized toner that passes through exposure to a photoreceptor. Patent Document 22 proposes the use of a toner that defines a volume average diameter, number average diameter, toner charge amount, toner projected image area ratio, toner BET specific surface area, and the like. An excellent image forming method using the method is desired.
[0030]
When using a technology called development / collection system or cleaner-less, the memory on the image blocks the exposure and disturbs the formation of the latent electrostatic latent image due to the influence of the residual toner. Therefore, negative memory tends to occur on the image. Furthermore, if there is a large amount of toner remaining after transfer, a positive memory tends to be generated on the image without being completely collected in the development process. Using a non-patterned member, the image quality tends to deteriorate.
[0031]
In particular, in a system using such a charging roller, especially when a large particle size external additive is added to the toner, the charging roller is contaminated when only DC charging is used, and the fuser of the photoconductor is problematic when AC charging is used. It becomes.
[0032]
In other words, an image forming method capable of satisfying a good image and a toner compatible therewith have not yet been provided due to stable developability, transferability, and cleaning properties under any environment for a long period of time.
[0033]
[Patent Document 1]
JP-A-4-204751
[Patent Document 2]
JP-A-5-346682
[Patent Document 3]
JP-A-6-313980
[Patent Document 4]
JP-A-6-332235
[Patent Document 5]
JP-A-7-92724
[Patent Document 6]
JP-A-7-104501
[Patent Document 7]
Japanese Patent Publication No. 5-69427
[Patent Document 8]
JP-A 64-20587
[Patent Document 9]
JP-A-2-259784
[Patent Document 10]
JP-A-4-50886
[Patent Document 11]
JP-A-5-165378
[Patent Document 12]
JP-A-2-511168
[Patent Document 13]
JP-A-5-2287
[Patent Document 14]
JP-A-6-250566
[Patent Document 15]
JP-A-8-292640
[Patent Document 16]
Japanese Patent Laid-Open No. 11-38730
[Patent Document 17]
JP 11-311890 A
[Patent Document 18]
Japanese Patent Laid-Open No. 11-147331
[Patent Document 19]
JP-A 63-149669
[Patent Document 20]
Japanese Patent Laid-Open No. 5-19662
[Patent Document 21]
JP-A-4-296766
[Patent Document 22]
Japanese Patent Laid-Open No. 5-188737
[0034]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object thereof is to provide an image forming method and a toner capable of stably forming a high-quality image in a system using an intermediate transfer member.
[0035]
The present invention provides a high-quality image in any environment and print pattern output in a system using an intermediate transfer member without contaminating the charging member and photosensitive member charging member of the developing unit with inorganic fine particles in the toner. An object is to provide an image forming method and a toner capable of stably forming an image.
[0036]
The present invention further provides an image forming method and toner capable of forming a stable and high-quality image even in a so-called cleaner-less system that does not have a system for cleaning residual toner on a latent image carrier. This is the issue.
[0037]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors paid attention to the primary and secondary particle diameters, the chargeability, the surface treatment, the amount added to the toner, etc. of the silica contained in the toner. It has been found that a good image can be stably obtained over a long period of time in any environment and print pattern output in a system with an intermediate transfer body that has the merit that it can be transferred to various materials. The present invention has been completed.
[0038]
That is, the present invention relates to an electrostatic latent image carrier, a charging unit that charges the surface of the electrostatic latent image carrier, an information writing unit that forms an electrostatic latent image on the charged electrostatic latent image carrier, and development. Developing means for visualizing the electrostatic latent image by supplying toner to the electrostatic latent image by the action of an electric field between the developer carrying member and the electrostatic latent image carrier that uniformly carries the developer in the unit by the regulating member; In an image forming method comprising: a transfer unit that transfers a visualized toner image onto a transfer material via an intermediate transfer member; and a fixing unit that heat-contacts and presses the toner image on the transfer material.
The toner is a toner having at least toner particles and an external additive,
The external additive has at least two silica fine powders (A) and (B) treated with a silane coupling agent and / or silicone oil,
The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
18 ≦ r (A) ≦ 38 nm, 6 ≦ r (B) ≦ 14 nm
And
In the volume average particle size distribution by a laser diffraction type particle size distribution analyzer, the silica fine powder (A) has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively. B) has one or more peaks or shoulders in the range from 1 μm to less than 100 μm, and In particles of 0.04 to 2000 μm The frequency ratio of 0.04 μm or more and less than 1 μm is 15% or less,
The toner relates to an image forming method, wherein the weight average particle diameter D4 is 4 ≦ D4 ≦ 10 μm.
[0039]
The present invention also provides an electrostatic latent image carrier, a charging unit that charges the surface of the electrostatic latent image carrier, an information writing unit that forms an electrostatic latent image on the charged electrostatic latent image carrier, A developing means for visualizing the electrostatic latent image by supplying toner to the electrostatic latent image by the action of an electric field between the developer bearing member and the electrostatic latent image bearing member that uniformly supports the developer in the developing unit by the regulating member; In a toner used in an image forming method, the image forming method includes: a transfer unit that transfers a visualized toner image onto a transfer material via an intermediate transfer member; and a fixing unit that heat-contacts and presses the toner image on the transfer material.
The toner is a toner having at least toner particles and an external additive,
The external additive has at least two silica fine powders (A) and (B) treated with a silane coupling agent and / or silicone oil,
The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
18 ≦ r (A) ≦ 38 nm, 6 ≦ r (B) ≦ 14 nm
And
In the volume average particle size distribution by a laser diffraction type particle size distribution analyzer, the silica fine powder (A) has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively. B) has one or more peaks or shoulders in the range from 1 μm to less than 100 μm, and In particles of 0.04 to 2000 μm The frequency ratio of 0.04 μm or more and less than 1 μm is 15% or less,
The toner relates to a toner having a weight average particle diameter D4 of 4 ≦ D4 ≦ 10 μm.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an image forming method such as an electrophotographic method or an electrostatic printing method, and relates to an image forming method using an intermediate transfer member. In the present invention, the toner used in the image forming method is a toner having at least toner particles and an external additive,
The external additive has at least two silica fine powders (A) and (B) treated with a silane coupling agent and / or silicone oil,
The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
18 ≦ r (A) ≦ 38 nm, 6 ≦ r (B) ≦ 14 nm
And
In the volume average particle size distribution by a laser diffraction type particle size distribution analyzer, the silica fine powder (A) has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively. B) has one or more peaks or shoulders in the range of 1 μm or more and less than 100 μm, and the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all peaks is 15% or less,
The toner has a weight average particle diameter D4 of 4 ≦ D4 ≦ 10 μm.
[0041]
When there is a member that is in pressure contact with the drum, such as a charging roller, cleaning blade, or transfer member, as the durability progresses, the member or drum becomes contaminated or worn, and the toner adheres to the drum surface or roller surface, or is fused. There are things to do.
[0042]
This is because the toner is slightly attached to the charging roller by continuous continuous paper passing, and if the hardness of the charging roller surface is not appropriate, the toner may be damaged or fused to the roller surface or drum surface, resulting in a defective image. It will end up.
[0043]
On the other hand, as a result of intensive studies, the present inventors have determined that the particle size of the external additive to be externally applied to the toner surface has a predetermined distribution, and further hydrophobizes the external additive, so It was found that the drum is less likely to be contaminated or damaged. It was also found that a stable image can be provided over a long period of time in any environment.
[0044]
Furthermore, by balancing the addition amount of the external additive, it has succeeded in achieving good toner charging properties, transfer properties, fixing properties, and member contamination resistance.
[0045]
Next, a favorable form of the toner of the present invention will be described.
[0046]
The toner used in the present invention is a toner having at least toner particles and an external additive, and the external additive includes at least two silica fine powders (A) treated with a silane coupling agent and / or a silicone oil. ) And (B) improve the charging stability of the toner in the environment. From the viewpoint of uniform charging of the toner, it is better to use the same treating agent for (A) and (B) silica.
[0047]
The primary average particle size r (A) of the silica fine powder (A) is preferably 18 to 38 nm, more preferably 20 to 32 nm, and still more preferably 22 to 28 nm. If it is smaller than 18 nm, the mechanical stress received from the charge imparting member (carrier in the case of two-component development, sleeve and regulating blade in the case of one-component development, etc.), especially when outputting a low-printing print, When a large number of sheets are printed, the external additive cannot be satisfactorily held on the toner particles, thereby causing fogging, scattering, transferability deterioration, and the like. On the other hand, when the thickness is larger than 38 nm, when filming on the photosensitive member or a charging roller is used, the charging roller is contaminated to cause image defects such as fogging and streaks.
[0048]
The primary average particle diameter r (B) of the silica fine powder (B) is preferably 6 to 14 nm, more preferably 7 to 13 nm, and further preferably 8 to 12 nm. If it is smaller than 6 nm, scattering due to toner fluidity being too high, excessive charging of the toner in a low-humidity environment, scattering, image density fluctuation, image unevenness due to non-uniform coating on the development carrier, etc. . On the other hand, if it is larger than 14 nm, the fluidity of the toner is too low to receive a uniform charging property, which causes deterioration of image quality (dot reproducibility), fogging and scattering particularly in a high humidity environment.
[0049]
The average particle size of the primary particles of the silica fine powder of the present invention was measured by taking a photograph of the surface of the toner particles magnified 500,000 times with a scanning electron microscope FE-SEM (S-4700, manufactured by Hitachi, Ltd.) A magnified photo is taken as the measurement target. The average particle diameter of primary particles is measured over 10 fields in an enlarged photograph, and the average is defined as the average particle diameter. Of the parallel lines drawn so as to be in contact with the contours of the primary particles of the fine powder, the one having the maximum distance between the parallel lines is defined as the particle size.
[0050]
The silica fine powder (A) preferably has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively, in the volume average particle size distribution by a laser diffraction type particle size distribution meter. More preferably, it has one or more peaks in the range of less than 0.6 μm and in the range of 1 μm to less than 60 μm, and each has one or more peaks in the range of 0.10 μm to less than 0.4 μm and 1 μm to less than 40 μm. More preferably.
[0051]
Furthermore, it has a peak in the range of 0.08 μm to 0.2 μm, a shoulder in the range of 0.2 μm to 0.8 μm, a peak in the range of 1 μm to 4 μm, and 4 μm to 20 μm. Having a peak in the range and having a shoulder in the range of 20 μm to 80 μm is the condition for best expressing the effects of the present invention.
[0052]
The position of the shoulder (shoulder) represents an intersection of a portion having the maximum inclination and a portion having the minimum inclination when a tangent is drawn to the shoulder portion on the particle size distribution profile.
[0053]
Silica forms aggregates or aggregates due to its high chargeability. The silica fine powder (A) forming the aggregate in the range of 0.04 μm or more and less than 1 μm in the volume average particle size distribution by the laser diffraction type particle size distribution meter in the present invention has a small number of collected silicas, and its cohesive strength is also small. Relatively weak. Silica (A) forming an aggregate in the range of 0.04 μm or more and less than 1 μm can be easily and uniformly added onto the toner surface because of its high chargeability and moderate size. At the time of transfer to an intermediate transfer member and further to a transfer material, spacer particles are formed between the toner, the photoreceptor and the belt, so that transferability can be maintained over a long period of time. In particular, the use of silica as in the present invention is preferable because the charge transfer on the intermediate transfer member is small and gives good transferability during transfer from the intermediate transfer member to the transfer material (secondary transfer). It becomes.
[0054]
Therefore, when the peak and shoulder do not exist within the range of 0.04 μm to 1 μm, good transferability cannot be maintained over a long period under various environments.
[0055]
On the other hand, silica in the range of 1 μm or more and less than 100 μm of the silica fine powder (A) has a large number of agglomerated silica, and its aggregability is strong. When added to the toner, it also exists as an aggregate and is often free from the toner because of its size. This free agglomerated silica is required to maintain developability and transferability during long-term continuous printing. This is because, in both the one-component system and the two-component system, the external additive that is well added on the toner is gradually buried in the toner due to mechanical stress received from the charging member in the developing device. Therefore, the developability and transferability are likely to deteriorate in the second half of continuous printing. Here, the agglomerated silica released from the toner in the range of 1 μm or more and less than 100 μm of the present invention is subjected to stress in the developing device, and gradually agglomerates are released to the order of submicron particle diameter. It becomes the form made. Therefore, even in the latter half of the durability, a good image can be provided without impairing the chargeability and transferability. When the peak and shoulder positions are less than 1 μm, the above effects are not sufficiently exerted. Conversely, when the peak and shoulder positions are greater than 100 μm, the aggregated particle diameter is too large, so that the charging member and the photoreceptor are partially contaminated. Causes a potty image on the spot.
[0056]
The main purpose of the fine silica powder (B) is to impart fluidity to the toner and to impart uniform high chargeability to the toner, and therefore it is preferable that no peak or shoulder exists in the range of 0.04 μm to 1 μm. The addition of the silica fine powder (B) gives a uniform high charge to the toner, so that it can be strongly transferred onto a transfer material (paper or the like) particularly in the secondary transfer system. Therefore, the system to which the silica fine powder (B) is added can maintain high coloring power even when the same is applied to the transfer material. Addition of the silica fine powder (B) makes it possible to control the amount ratio of the solid image and the line image (the amount of the line image / the amount of the solid image) in the range of 1.0 to 1.3. Even in the case of an image, transferability, fixability, and image characteristics are not impaired. This is because, when the chargeability of the toner on the developing carrier is low, a large amount of toner accumulates on the line image due to the edge effect in the developing electric field when trying to obtain a certain solid image. In such a case, problems such as poor transfer of the line image, poor fixing (offset, etc.), and image chatter during fixing occur.
[0057]
Further, the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all peaks is preferably 15% or less, and more preferably 8% or less. When a peak or shoulder exists in the range of 0.04 μm to 1 μm, or the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all peaks exceeds 15%, the flow of toner can be achieved by adding a small amount of silica fine powder (B). It becomes difficult to impart the property. In this case, the chargeability of the toner becomes insufficient, and image quality is deteriorated, and toner scattering and fogging easily occur in a high humidity environment. When a large amount of fine silica powder (B) is added to ensure fluidity, the toner is likely to be overcharged, especially when it is charged up in a low-humidity environment, and the coatability on the development carrier becomes non-uniform. Or cause low image density. In addition, the phenomenon that the low-temperature fixability deteriorates also occurs.
[0058]
On the other hand, the presence of silica in the range of 1 μm or more and less than 100 μm with respect to the silica fine powder (B) after balancing the addition amount of the silica fine powder (A) and (B) for suitably expressing the present invention. Necessary for maintaining developability in the latter half of the durability. The silica fine powder (B) preferably has one or more peaks or shoulders in the range of 1 μm or more and less than 100 μm, more preferably one or more peaks or shoulders in the range of 1 μm or more and less than 80 μm. More preferably, it has one or more peaks or shoulders in the range of less than 60 μm. When the silica fine powder (B) has a peak and shoulder position of less than 1 μm, the above effect is not sufficiently exhibited. On the other hand, when it is greater than 100 μm, the aggregated particle diameter is too large. Partially contaminated, causing streaks and spotted spots.
[0059]
In the present invention, the peak position of the silica fine powder (B) is most preferably in the range of 1 μm to 30 μm, as in the case of the silica fine powder (A), in terms of all the balances.
[0060]
That is, the main purpose of each of the silica fine powders (A) and (B) is to improve the transferability of the toner and maintain the developability in the latter half of the durability of the silica fine powder (A). To provide fluidity and maintain developability in the latter half of the durability. It is difficult to obtain this effect with a single silica. By using the silica fine powders (A) and (B) as in the present invention, a good and stable image can be obtained for a long time in a secondary transfer system for the first time. Can be provided.
[0061]
Here, a method of measuring the volume average particle size distribution by the laser diffraction type particle size distribution meter in the present invention will be described.
[0062]
The particle size of the fine particles is measured using a Coulter LS-230 type particle size distribution meter (manufactured by Coulter, Inc.) of a laser diffraction type particle size distribution meter. Ethanol is used as a measurement solvent. Wash and replace the measurement system of the particle size distribution analyzer several times with ethanol and execute the background function.
[0063]
Next, a sample solution is obtained as described below, and the sample solution is gradually added into the measurement system of the measurement device so that the PIDS (concentration) on the screen of the device is 45 to 55%. The sample concentration is adjusted and measured, and the frequency ratio is obtained from the distribution calculated from the volume distribution.
[0064]
The measurement was carried out by setting the refractive index of ethanol as 1.36 as the device coefficient and 1.08 (real part) −0.00i (imaginary part) as the optical model.
[0065]
The particle size measurement range of the Coulter LS-230 type particle size distribution meter of the laser diffraction type particle size distribution meter in the present invention is 0.04 μm to 2000 μm. The measurement temperature was 20 ° C to 25 ° C.
[0066]
As a method for preparing a sample in the present invention, 0.4 g of a fine powder to be measured is weighed, put into a beaker containing 100 ml of ethyl alcohol, and stirred. Transfer the beaker to the ultrasonic vibration layer and treat for 3 minutes. Immediately after completion of the treatment, the dispersion solution is added to the measurement part filled with ethanol until the measurement allowable concentration is reached, and measurement is started.
[0067]
In addition, as the ultrasonic vibration layer in the present invention, ULTRASONIC CLEANER VS-150 type (frequency 50 kHz, maximum output 150 W) manufactured by Inoue Seieido Co., Ltd. was used.
[0068]
The sample concentration in this measurement varies between liquid / solid and solid / solid, but it is close to the ratio of the external additive added to the toner in the external addition process, and should be considered as a model of the dispersion state of the fine powder in the external addition operation. Is possible.
[0069]
On the other hand, in order to measure the fine powder from the toner added externally, 4 g of the toner to be measured is weighed, put into a beaker containing 100 ml of ethyl alcohol, and stirred for 1 minute by stirring with a stirrer. Transfer the beaker to the ultrasonic vibration layer and treat for 1 minute. In the case of magnetic toner, the toner is separated by a magnet to obtain a dispersion solution. The resulting solution is transferred to the ultrasonic vibration layer and treated again for 1 minute. Immediately after completion of processing, measurement is started. In the case of non-magnetic toner, the toner is separated by centrifugation or standing to obtain a dispersion solution. The resulting solution is transferred to the ultrasonic vibration layer and treated again for 1 minute. Immediately after completion of processing, measurement is started.
[0070]
In the present invention, the silica fine powder (A) preferably has a frequency ratio of 0.04 μm or more and less than 1 μm to the entire peak of 10% to 80%.
[0071]
If the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all the peaks is less than 10%, the transferability of the toner deteriorates and a satisfactory image cannot be obtained.
[0072]
If the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all peaks exceeds 80%, the amount of agglomerated silica in the range of 1 μm to 100 μm decreases, and it becomes difficult to maintain good developability in the latter half of durability. Further, the amount of inorganic fine particles released from the toner surface increases, and the adhesion to the charging member, developing member, photosensitive drum, etc. tends to deteriorate.
[0073]
When the frequency ratio of 0.04 μm or more and less than 1 μm with respect to all peaks is 20% to 70%, the above-described effect is further improved.
[0074]
Furthermore, the fact that the frequency ratio of 20 μm or more and less than 2000 μm with respect to all the peaks is less than 16% is also a preferable form for satisfactorily expressing the present invention. The particle size range of 20 μm or more and less than 2000 μm is larger than the toner base particles and is equal to or smaller than the opening of the sieve that removes coarse particles after the external addition treatment.
[0075]
If the frequency ratio of 20 μm or more and less than 2000 μm with respect to the entire peak is 16% or more, it adheres to the charging member, the developing member, the photosensitive drum, etc., and image defects are likely to occur. When the frequency ratio of 20 μm or more and less than 2000 μm with respect to all peaks is less than 12%, the above-described effect is further improved.
[0076]
In the present invention, it is preferable that the half-width of the maximum peak in the range of 1 μm or more and less than 100 μm is 5 μm to 25 μm for both silica fine powders (A) and (B). This half width shows the distribution state of the composite of inorganic fine powder.
[0077]
If the full width at half maximum of the maximum peak in the range of 1 μm or more and less than 100 μm is less than 5 μm or there is no peak, the toner and the developer are likely to be densely packed, and it is difficult to maintain the developer deterioration well for a long time. It becomes.
[0078]
When the full width at half maximum of the maximum peak in the range of 1 μm or more and less than 100 μm exceeds 25 μm, coarse particles increase, and the toner adheres to the charging member, the developing member, the photosensitive drum, and the like, and easily causes image defects.
[0079]
More preferably, the half width is 8 μm to 20 μm.
[0080]
In the present invention, the volume average particle size measured by a laser diffraction type particle size distribution meter is preferably 0.1 μm to 20 μm.
[0081]
When the volume average particle size is less than 0.1 μm, the number of particles having a spacer effect is reduced, transferability is deteriorated, and toner and developer are easily filled, and developer deterioration is likely to be accelerated. More preferably, the volume average particle diameter is 0.3 μm to 12 μm.
[0082]
In addition, it is difficult to determine the size of the particles by the specific surface area by nitrogen adsorption by the BET method of fine powder. However, the degree of moisture adsorption and the degree of charged sites vary depending on the surface area. Is preferred.
[0083]
The silica fine powder (A) in the present invention has a specific surface area of 30 to 100 m by nitrogen adsorption by the BET method. ² / G is good.
[0084]
Specific surface area of fine powder (A) by nitrogen adsorption by BET method is 30m ² If it is less than / g, it is considered that the cohesiveness of the powder is too high and the composite particles are too large, and they are released from the toner and easily contaminate the member. Specific surface area of fine powder (A) by nitrogen adsorption by BET method is 100m ² When it is larger than / g, it is considered that the composite particles in the present invention are difficult to form, and the effects of the invention are hardly exhibited.
[0085]
The silica fine powder (B) in the present invention has a specific surface area of 100 to 200 m by nitrogen adsorption by the BET method. ² / G is good development characteristics in the image forming apparatus of the present invention.
[0086]
The specific surface area of fine powder (A) by nitrogen adsorption by BET method is 100m ² If it is less than / g, the flowability and uniform chargeability to the toner are likely to be insufficient, which causes deterioration of image quality (dot reproducibility) and fogging and scattering particularly in a high humidity environment. In addition, the amount of line paste / solid image tends to exceed 1.3, and image defects such as transfer defects, fixing defects, and clear images tend to occur. Conversely, 200m ² When it exceeds / g, embedding of silica particles in the toner becomes remarkable, and even when the silica fine powder (A) used in the present invention is added, developability tends to be deteriorated in the latter half of the durability.
[0087]
The measurement of the BET specific surface area of the powder is performed as follows using a specific surface area meter autosorb 1 manufactured by QUANTACHROME. About 0.1 g of a measurement sample is weighed in a cell, temperature is 40 ° C., and the degree of vacuum is 1.0 × 10. ^-3 Degassing is performed for 12 hours or more at mmHg. Thereafter, nitrogen gas is adsorbed while being cooled with liquid nitrogen, and a value is obtained by a one-point method.
[0088]
The toner of the present invention has a weight average particle diameter D4 of preferably 4 μm to 10 μm, more preferably 5 μm to 9 μm, and even more preferably 6 μm to 8 μm. If it is smaller than 4 μm, it becomes easy to charge up especially in a low humidity environment, and a large change in electrification in both low temperature and low humidity and high temperature and high humidity environments, scattering and fogging, poor cleaning of transfer residual toner on the photoreceptor, Problems such as drum fusion and charging member contamination are likely to occur. In addition, transferability is deteriorated particularly in a high humidity environment. Further, when a large amount of an external additive is added to maintain the fluidity of the fine particle toner, the fixability is also deteriorated. On the other hand, when the weight average particle diameter of the toner is larger than 10 μm, the image quality such as flickering is deteriorated. The toner particle size distribution should be moderately sharp. Specifically, the number average of 4 μm or less of the number average particle diameter is preferably 5 to 35%, more preferably 8 to 20%. On the contrary, as the coarse powder side, the volume percentage of 12.7 μm or more of the volume average particle diameter is preferably 2.0% or less, more preferably 0.5% or less. If the number% of 4 μm or less is smaller than 5%, it becomes difficult to faithfully fill the latent image dots, the moist feeling in the halftone image is lost, and the image becomes sticky. If it is larger than 35%, the mirroring force with the charge imparting member increases, and charging of new toner is inhibited, so that image defects such as fogging and scattering are likely to occur. When the volume percentage of 12.7 μm or more on the coarse powder side is larger than 2.0%, the selective development makes it easy for the coarse powder to accumulate in the developing device, reducing the total charge amount of the toner, fogging, and transfer defects. Such image defects are likely to occur.
[0089]
Further, the addition amount W (A) of the fine silica powder (A) of the present invention is preferably 0.05 to 1.5 parts by mass, and 0.1 to 1.1 with respect to 100 parts by mass of the toner particles. More preferably.
[0090]
When the addition amount of the silica fine powder (A) is less than 0.05 parts by mass, the transferability is deteriorated. On the other hand, when the amount is larger than 1.5 parts by mass, the material released from the toner tends to contaminate the member.
[0091]
Further, the addition amount W (B) of the silica fine powder (B) of the present invention is preferably 0.05 to 1.8 parts by mass, and 0.1 to 1.5 with respect to 100 parts by mass of the toner particles. More preferably.
[0092]
When the amount of silica fine powder (B) added is less than 0.05 parts by mass, the flowability and uniform chargeability to the toner are likely to be insufficient, and the image quality (dot reproducibility) deteriorates, especially in a high humidity environment. Causes fog and scattering below. In addition, the amount of line paste / solid image tends to exceed 1.3, and image defects such as transfer defects, fixing defects, and clear images tend to occur.
[0093]
On the other hand, if it is larger than 1.8 parts by mass, scattering due to too high fluidity of the toner, excessive charging of the toner in a low-humidity environment, scattering, image density fluctuation, and uneven coating on the developing carrier. Causes uneven image coming. In addition, the low temperature fixability is deteriorated.
[0094]
Further, the average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the flow particle image measuring apparatus for toner of the present invention is preferably 0.950 to 1.00, preferably 0.960 to More preferably, it is 1.00.
[0095]
When the average circularity is less than 0.950, the toner shape becomes very irregular, so the toner charge amount distribution tends to be broad, and when a large number of copies are made, the distribution is expanded by selective development. . For this reason, fog and scattering are likely to occur. In addition, the toner transfer efficiency during continuous paper feeding deteriorates, and the density unevenness of the solid image is likely to occur. Further, the cleanerless system causes a charging failure due to an increase in the residual toner, resulting in problems such as fogging. That is, by using the silica fine powders (A) and (B) of the present invention for a toner having a high degree of circularity in which transferability and uniform chargeability are easily obtained, stable developability and fixability can be provided over a longer period of time. It will be a thing.
[0096]
Here, the flow type particle image measuring apparatus is an apparatus that statistically performs image analysis of particle imaging, and the average circularity is calculated by the arithmetic average of the circularity obtained by the following equation using the apparatus.
[0097]
[Expression 1]

[0098]
In the above equation, the perimeter of the particle projection image is the length of the contour line obtained by connecting the edge points of the binarized particle image, and the perimeter of the equivalent circle is the binarized particle This is the length of the outer circumference of a circle having the same area as the image. The equivalent circle diameter is the diameter of a circle having the same area as the area of the measured two-dimensional image of the particles.
[0099]
FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.) is used as a flow type particle image measuring device.
[0100]
As a measuring method, 0.02 g of a measurement sample is added to 10 ml (20 ° C.) of a solution prepared by adding 0.1 to 0.5 mass% of a surfactant (preferably Wako Pure Chemicals Contaminone) to ion-exchanged water. A sample dispersion was prepared by uniformly dispersing.
[0101]
As a means for dispersion, an ultrasonic disperser UM-50 manufactured by SMT Co., Ltd. (vibrator is a titanium alloy tip of 5φ) is used, and the dispersion time is set to 5 minutes, and the temperature of the dispersion medium does not exceed 40 ° C. Cooled to. In the measurement, the range of 0.60 to 400 μm is divided into 226 channels, and in the actual measurement, particles are measured in a range where the equivalent circle diameter is 0.60 μm or more and less than 159.21 μm.
[0102]
The standard deviation of circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow-type particle image measuring device of the present invention is preferably from 0.010 to 0.040, preferably 0.015. More preferably, it is -0.035.
[0103]
When the standard deviation of the circularity of the toner of the present invention exceeds 0.040, the toner shape distribution is widened, so that the uniform transfer property is deteriorated and the density of the solid image is likely to be uneven. In addition, the cleanerless system tends to cause charging failure due to an increase in residual toner.
[0104]
When the standard deviation of the circularity of the toner of the present invention is less than 0.010, reproducibility and yield are remarkably deteriorated in production, which not only leads to an increase in cost but also the toner such as a photoreceptor and a transfer belt. Easy to clean.
[0105]
From the viewpoint that the toner of the present invention should be nearly spherical as described above, a pulverized toner obtained by mechanically pulverizing a pulverized toner obtained by mixing raw materials, kneading and pulverizing with a turbo mill or the like, or a polymerization It is preferably a polymerized toner obtained by suspension polymerization of a monomer composition comprising a polymerizable monomer, a colorant, a release agent and a polymerization initiator in an aqueous medium. In particular, polymerized toner is preferable in consideration of transferability and developability with high circularity.
[0106]
The toner of the present invention can be applied to both a negatively charged toner and a positively charged toner. However, considering the negative chargeability of silica, the negative toner can express the present invention better.
[0107]
The silica fine powders (A) and (B) of the present invention are preferably hydrophobized in order to maintain hydrophobicity in a high humidity environment. In particular, it is more preferable to treat with a silane coupling agent or silicone oil.
[0108]
Further, from the viewpoint of uniform chargeability, it is preferable to use the same treating agent as the treating agent used for the silica fine powders (A) and (B). That is, it is preferable that both the silica fine powders (A) and (B) are treated with a silane coupling agent or a silicone oil.
[0109]
The silane coupling agent may be used in an amount of 1 to 40 parts by mass, preferably 2 to 35 parts by mass with respect to 100 parts by mass of silica before the coupling treatment. When it is 1 to 40 parts by mass, moisture resistance is improved and aggregates are hardly generated.
[0110]
Examples of the silane coupling agent used in the present invention include those represented by the following general formula.
[0111]
RmSiYn
[Wherein, R represents an alkoxy group or a chlorine atom, m is an integer of 1 to 3, and Y represents a hydrocarbon group (for example, an alkyl group, a vinyl group, a glycidoxy group, a methacryl group). , N is an integer from 3 to 1].
[0112]
For example, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethylsilane, vinyltriacetoxysilane , Divinylchlorosilane, dimethylvinylchlorosilane, and the like. Among them, hexamethyldisilazane is preferable from the viewpoint of improving the hydrophobicity well and suppressing the difference in chargeability depending on the toner environment.
[0113]
The silica silane coupling agent treatment is a dry treatment in which the vaporized silane coupling agent is reacted with the silica made into a cloud by stirring, or the silica silane powder is dispersed in a solvent and the silane coupling agent is dropped. It can be processed by a generally known method such as a wet method.
[0114]
Silica can be produced by a dry process based on vapor phase oxidation of silicon halides (for example, thermal decomposition oxidation reaction in an oxygen / hydrogen flame), acid, ammonia, salts such as sodium silicate, alkaline earth metal silicate, silicate, Silica obtained by a wet method using decomposition with alkali salts is used. In particular, the preferred silica of the present invention is one produced by a dry method, and the amorphous is preferably used as the crystal type.
[0115]
In general, the silicone oil to be subjected to silica surface treatment is preferably represented by the following formula.
[0116]
[Chemical 1]

[In the formula, R ₁ ~ R _Ten May be the same or different and each represents hydrogen, a hydroxyl group, an alkyl group, a halogen, a phenyl group, a phenyl group having a substituent, a fatty acid group, a polyoxyalkylene group or a perfluoroalkyl group, and m and n are integers. Show]
[0117]
As a preferable silicone oil, the viscosity at 25 ° C. is 5 to 200 mm. ² / S is preferably used, 40 to 80 mm ² / S is more preferably used from the viewpoint of uniform processing. A silicone oil having a low molecular weight and a low viscosity is not preferable because volatile matter may be generated by heat treatment, while a silicone oil having a high molecular weight and a high viscosity is difficult to perform a surface treatment operation. As the silicone oil, methyl silicone oil, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, and polyoxyalkyl-modified silicone oil are preferable.
[0118]
When applied to a positive toner, the silicone oil may be a modified silicone oil having an organo group having at least one nitrogen atom in the side chain. For example, a modified silicone oil having at least a partial structure represented by the following formula can be given.
[0119]
[Chemical 2]

(Wherein R ₁ Represents hydrogen, an alkyl group, an aryl group or an alkoxy group, and R ₂ Represents an alkylene group or a phenylene group, R _Three And R _Four Represents hydrogen, an alkyl group or an aryl group, and R _Five Represents a nitrogen-containing heterocyclic group).
[0120]
The alkyl group, aryl group, alkylene group, and phenylene group may have an organo group having a nitrogen atom, or may have a substituent such as halogen.
[0121]
The above silicone oil is preferably used in the same polarity as the toner particles in order to improve the charging characteristics of the toner.
[0122]
A known technique is used as a method of treating silica with silicone oil.
[0123]
For example, the inorganic fine powder and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying the silicone oil onto the inorganic fine powder may be used. Alternatively, it may be prepared by dissolving or dispersing silicone oil in a suitable solvent, mixing with inorganic fine powder, and then removing the solvent.
[0124]
Silicone oil is used in an amount of 1.5 to 60 parts by mass, preferably 3.5 to 40 parts by mass, based on 100 parts by mass of silica to be treated. When the amount is 1.5 to 60 parts by mass, the surface treatment with silicone oil can be uniformly performed, and filming and voiding can be suitably prevented, and the toner chargeability is prevented from being deteriorated due to moisture absorption under high humidity, and is durable. It is possible to prevent a decrease in image density. When surf fixing is used, image defects such as fixing scattering can be prevented. It is possible to prevent a decrease in toner fluidity and to prevent fogging.
[0125]
Silica has a hydrophobicity of 95% or more, preferably 97% or more. When the hydrophobicity is 95% or more, the moisture resistance is improved and the image density is lowered under high humidity.
[0126]
Further, unlike the corona charging method and the magnetic brush charging method, in the roller charging type image forming apparatus, the charging roller and the photosensitive member rotate while contacting with a certain pressure. In particular, in a cleanerless system without a cleaning blade, untransferred toner passes through the nip, and the toner and external additives are likely to be fused to the roller and the photoreceptor. In that case, it is preferable to treat the silica fine powder (A) having a large particle size with a silicone oil.
[0127]
Furthermore, the fine powder (A) includes both the amount of composite particles in the range of 0.1 μm or more and less than 1 μm required for the present invention and the amount of composite particles in the range of 20 μm or more and less than 100 μm for the effect of preventing fusion. It is preferable to control. As the method, classification treatment or crushing treatment may be performed.
[0128]
Examples of the method include a method of performing particle size selection using an air classifier, a method of rotating a rotor to loosen composite particles by impact (for example, a hybridizer, a cosmomizer, etc.), and a method of a pin mill, a jet mill, or the like used for pulverization. However, there is no limitation on the apparatus that can control the particle size distribution of the present invention.
[0129]
In addition to the fine powders (A) and (B) used in the present invention, fine powders may be further added for adjusting the charge amount, assisting fluidity, and the like.
[0130]
For example, examples of the fluidity-imparting agent include metal oxides (silicon oxide, aluminum oxide, titanium oxide, etc.), carbon black, silica, and the like, and those subjected to hydrophobic treatment are more preferable.
[0131]
Abrasives include metal oxides (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitrides (silicon nitride, etc.), carbides (silicon carbide, etc.), metal salts (calcium sulfate, barium sulfate, etc.) , Calcium carbonate, etc.).
[0132]
Examples of the charge controllable particles include metal oxides (such as tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide) and carbon black.
[0133]
Using a release agent in the toner of the present invention is also a good form for achieving oilless fixing. Examples of the release agent that can be used in the present invention include polymethylene waxes such as paraffin wax, polyolefin wax, microcrystalline wax, and Fischer-Tropsch wax, amide wax, higher fatty acid, long chain alcohol, ketone wax, ester wax, and grafts thereof. Derivatives such as compounds and block compounds may be mentioned, and distillation may be performed as necessary.
[0134]
Further, ester waxes represented by the following general structural formula are particularly preferable.
[0135]
[Chemical Formula 3]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R ₁ And R ₂ Is an organic group having 1 to 40 carbon atoms and R ₁ And R ₂ And n and m are integers of 0 to 40, and n and m are not 0 at the same time)
[0136]
[Formula 4]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R ₁ Represents an organic group having 1 to 40 carbon atoms, n and m represent integers of 0 to 40, and n and m are not 0 at the same time)
[0137]
[Chemical formula 5]

(Wherein, a and b represent an integer of 0 to 3, a + b is 3 or less, k is an integer of 1 to 3, and R ₁ And R ₂ Is an organic group having 1 to 40 carbon atoms and R ₁ And R ₂ And a group having a carbon number difference of 3 or more and R _Three Represents an organic group having 1 or more carbon atoms, n and m represent integers of 0 to 40, and n and m are not 0 simultaneously. )
[0138]
The full width at half maximum of the release agent contained in the toner of the present invention is measured in accordance with ASTM D3418-82. The half-value width of the endothermic peak here is the temperature width of the endothermic chart that is half the height of the peak from the baseline in the endothermic peak. The half-value width of the endothermic peak of the release agent is preferably 15 ° C. or less, more preferably 7 ° C. or less.
[0139]
When the half width exceeds 15 ° C., the crystallinity is not high, so that the mold release agent has a soft hardness and promotes contamination of the photoreceptor and the charging roller.
[0140]
Moreover, the endothermic peak value in the DSC endothermic curve of the release agent in the present invention is measured in accordance with ASTM D3418-82.
[0141]
The release agent used in the present invention is preferably a compound having an endothermic peak value in the DSC curve of 50 to 150 ° C, more preferably a compound of 60 to 120 ° C.
[0142]
When the endothermic peak value is less than 50 ° C., the self-cohesive force of the release agent is weak, so it is difficult to form the inside or center of the toner particle, and the release agent is deposited on the surface of the toner particle during the production of the toner particle, It easily contaminates the photoconductor and charging roller.
[0143]
On the other hand, if the endothermic peak exceeds 150 ° C., the release agent does not easily permeate during fixing, and the fixing property at a low temperature and the fixing property of secondary colors (red, green, blue) having a large amount of toner development are deteriorated. . Further, when toner particles are produced by a direct polymerization method, the solubility in the polymerizable monomer composition is reduced, and the toner particle size of the polymerizable monomer composition in the aqueous medium is reduced. The release agent is precipitated during the granulation of the droplets, making granulation difficult, which is not preferable.
[0144]
As a molecular weight of a mold release agent, a thing with a mass mean molecular weight (Mw) of 300-1,500 is preferable. If it is less than 300, exposure of the release agent to the toner particle surface is likely to occur, developability is deteriorated, and fogging is likely to occur in a high temperature and high humidity environment. In addition, the charging roller is significantly contaminated. On the other hand, when the weight average molecular weight of the release agent exceeds 1,500, the low-temperature fixability is lowered and the OHT transparency is also deteriorated.
[0145]
The weight average molecular weight of the release agent is particularly preferably in the range of 400 to 1,250. Further, when the ratio of the mass average molecular weight / number average molecular weight (Mw / Mn) is 1.5 or less, the maximum peak of the DSC endothermic curve of the release agent becomes sharper, and the mechanical strength of the toner particles at room temperature is increased. In particular, excellent toner physical properties can be obtained, which show sharp melting characteristics upon fixing.
[0146]
The penetration of the release agent is 15 degrees or less, more preferably 8 degrees or less. When the angle exceeds 15 degrees, the contamination of the photoconductor and the charging roller is promoted as in the case where the half width of the release agent exceeds 10 ° C.
[0147]
The release agent may be blended in an amount of 1 to 35 parts by weight, preferably 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin.
[0148]
As the binder resin used in the toner of the present invention, the following binder resins can be used.
[0149]
For example, styrene and its substituted homopolymers such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride; phenol Resin; natural modification Enol resin; Naturally 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; Petroleum resin can be used. Preferred binder materials include styrene copolymers or polyester resins.
[0150]
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; for example, ethylene, propylene, Ethylene monomers such as ethylene; vinyl monomers such as vinyl methyl ketone, vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Are used alone or in combination of two or more.
[0151]
The styrenic polymer or styrenic copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.
[0152]
As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; , Divinyl aniline, divinyl ether, divinyl sulfide, divinyl sulfone and the like; and compounds having three or more vinyl groups are used alone or as a mixture.
[0153]
As addition amount of a crosslinking agent, 0.001-10 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.
[0154]
The toner of the present invention may contain a charge control agent.
[0155]
The following substances are used for controlling the toner to be negatively charged.
[0156]
For example, organometallic compounds and chelate compounds are effective, and there are monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal compounds. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol. Further, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene- An acrylic-sulfonic acid copolymer, a nonmetal carboxylic acid compound, etc. are mentioned. Further, a resin having the charge control compound pendant may be internally added to the toner.
[0157]
The following substances are used to control the toner to be positively charged.
[0158]
For example, modified products such as nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and the like Onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and their lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, Gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; Over DOO, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination of these alone, or two or more kinds. Among these, a charge control agent such as a nigrosine-type quaternary ammonium salt is particularly preferably used. Further, a resin having the charge control compound pendant may be internally added to the toner.
[0159]
These charge control agents may be used in an amount of 0.01 to 20 parts by mass (more preferably 0.5 to 10 parts by mass) with respect to 100 parts by mass of the resin component.
[0160]
As the colorant used in the present invention, a black colorant that is toned in black using carbon black, grafted carbon or the following yellow / magenta / cyan colorant is used.
[0161]
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigment Yellow 3, 7, 10, 12, 13, 14, 15, 17, 23, 24, 60, 62, 74, 75, 83, 93, 94, 95, 99, 100, 101, 104, 108, 109, 110 111, 117, 123, 128, 129, 138, 139, 147, 148, 150, 155, 166, 168, 169, 177, 179, 180, 181, 183, 185, 191, 192, 170, 199, etc. Preferably used.
[0162]
In addition, C.I. I. Solvent Yellow 33, 56, 79, 82, 93, 112, 162, 163, C.I. I. Disperse Yellow 42, 64, 201, 211 and the like.
[0163]
If necessary, yellow pigments and dyes may be used alone, or several kinds of pigments and dyes may be used in combination.
[0164]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 122, 146, 150, 166, 169, 177, 184, 185, 202 206, 220, 221, 238, 254, 269 and C.I. I. Pigment Violet 19 and the like are particularly preferable.
[0165]
If necessary, magenta pigments and dyes may be used alone, or several kinds of pigments and dyes may be used in combination.
[0166]
As the cyan colorant used in the present invention, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.
[0167]
If necessary, cyan pigments and dyes may be used alone, or several kinds of pigments and dyes may be used in combination.
[0168]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.
[0169]
Next, a method for producing the toner used in the present invention will be described. The toner used in the present invention can be manufactured using a pulverized toner manufacturing method and a polymerized toner manufacturing method.
[0170]
In the present invention, the method for producing a pulverized toner includes a binder resin, a low softening point substance, a pigment as a colorant, a dye or a magnetic substance, and, if necessary, a charge control agent and other additives such as a Henschel mixer and a ball mill. Mix thoroughly with a mixer; the resulting mixture is melt-kneaded using a heat kneader such as a heating roll, kneader, extruder, etc., while the resin components are mutually compatible, a low softening point substance, a pigment, a dye, The magnetic material is dispersed or dissolved; the obtained kneaded product is cooled and solidified, and then pulverized and classified to obtain a toner.
[0171]
Further, if necessary, the toner and the desired additive can be sufficiently mixed with a mixer such as a Henschel mixer to obtain the toner used in the present invention.
[0172]
In the present invention, a polymerized toner is produced by a method described in Japanese Examined Patent Publication No. 56-13945 or the like using a disk or a multi-fluid nozzle to atomize the molten mixture into the air to obtain a spherical toner, or Japanese Examined Patent Publication No. 36-10231. JP-A-59-53856, JP-A-59-61842, a method of directly producing toner using a suspension polymerization method, An emulsion polymerization method typified by a dispersion polymerization method in which a toner is directly produced using an aqueous organic solvent in which the coalescence is insoluble, or a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator, After making the polar emulsion polymer particles, it is possible to produce a toner using a hetero-aggregation method in which polar particles having opposite charges are added and associated.
[0173]
However, in the dispersion polymerization method, the obtained toner shows a very sharp particle size distribution, but the manufacturing apparatus is used from the viewpoint of the treatment of the waste solvent and the flammability of the solvent due to the narrow selection of materials to be used and the use of organic solvents. Complicated and complicated. An emulsion polymerization method typified by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform. However, when the used emulsifier and initiator terminals are present on the surface of the toner particles, the environmental characteristics are easily deteriorated.
[0174]
Therefore, in the present invention, a suspension polymerization method under normal pressure or under pressure, which can obtain a fine particle toner having a sharp particle size distribution relatively easily, is particularly preferable. A so-called seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized using a polymerization initiator can be suitably used in the present invention.
[0175]
When the direct polymerization method is used in the toner manufacturing method of the present invention, the toner can be specifically manufactured by the following manufacturing method. Addition of low softening point substance, colorant, charge control agent, polymerization initiator and other additives to the monomer, and the monomer system that is uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc. is a dispersion stabilizer Disperse in the aqueous phase containing the water with a normal stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and time so that the monomer droplets have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and in order to remove unreacted polymerizable monomers and by-products that cause odor during toner fixing, the latter half of the reaction, or the completion of the reaction. A part of the aqueous medium may be distilled off later. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer system.
[0176]
A more preferable toner used in the present invention is manufactured by a direct polymerization method in which a low softening point substance is encapsulated in an outer shell resin layer in a tomographic measurement method of a toner using a transmission electron microscope (TEM). Is. From the viewpoint of fixing properties, it is necessary to include a large amount of a low softening point substance in the toner. Therefore, it is necessary to encapsulate the necessary low softening point substance in the outer shell resin. If the toner cannot be encapsulated, it will not be finely pulverized unless special freeze pulverization is used in the pulverization process, resulting in only a wide particle size distribution, and toner fusion to the device will also occur. That's bad. In freeze pulverization, the apparatus becomes complicated to prevent dew condensation on the apparatus, and if the toner absorbs moisture, the workability of the toner is deteriorated, and it is necessary to add a drying process. As a specific method for encapsulating the low softening point substance, the polarity of the material in the aqueous medium is set to be smaller than that of the main monomer, and a small amount of a large polar resin or simple substance is used. By adding a monomer, a toner having a so-called core-shell structure in which a low softening point substance is coated with an outer shell resin can be obtained. Toner particle size distribution control and particle size control can be done by changing the type and amount of a poorly water-soluble inorganic salt or protective colloid dispersant and mechanical device conditions such as rotor peripheral speed, number of passes, and stirring blades. The predetermined toner of the present invention can be obtained by controlling the stirring conditions such as the shape, the container shape, or the solid content concentration in the aqueous solution.
[0177]
In the present invention, as a specific method for measuring the tomographic plane of the toner, there are four cured products obtained by sufficiently dispersing the toner in a room temperature curable epoxy resin and curing it in an atmosphere at a temperature of 40 ° C. for two days. After staining with ruthenium trioxide and, if necessary, osmium tetroxide, a flaky sample was cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner was measured using a transmission electron microscope (TEM). In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide a contrast between materials by utilizing a slight difference in crystallinity between the low softening point substance used and the resin constituting the outer shell.
[0178]
A monofunctional polymerizable monomer or a polyfunctional polymerizable monomer can be used as the vinyl polymerizable monomer capable of radical polymerization used when a toner is produced by a polymerization method.
[0179]
Monofunctional polymerizable monomers include styrene, α-methyl styrene, β-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p -Styrene polymerizable monomers such as phenyl styrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n -Hexyl acrylate, 2-ethylhexyl acrylate Acrylic polymerizable monomers such as relate, n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; methyl methacrylate, ethyl Methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl Methacrylate, diethyl phosphate ethyl methacrylate, dibutyl phosphate ethyl Methacrylic polymerizable monomers such as methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether, Examples thereof include vinyl polymerizable monomers such as vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.
[0180]
As polyfunctional polymerizable monomers, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol Diacrylate, polypropylene glycol diacrylate, 2,2'-bis [4- (acryloxy-diethoxy) phenyl] propane, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2′-bis [4- (methacryloxy-diethoxy) phenyl] propane, Examples include 2,2′-bis [4- (methacryloxy / polyethoxy) phenyl] propane, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.
[0181]
The monofunctional polymerizable monomers can be used alone or in combination of two or more, or a monofunctional polymerizable monomer and a polyfunctional polymerizable monomer can be used in combination. Moreover, it is also possible to use the said polyfunctional polymerizable monomer as a crosslinking agent.
[0182]
In the present invention, it is preferable to use a polar resin together in order to form a core-shell structure in the toner. Examples of polar resins such as polar polymers and polar copolymers that can be used in the present invention are given below.
[0183]
Polar resins include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, or copolymers of nitrogen-containing monomers and styrene-unsaturated carboxylic acid esters; nitriles such as acrylonitrile Monomer; halogen-containing monomer such as vinyl chloride; unsaturated carboxylic acid such as acrylic acid and methacrylic acid; unsaturated dibasic acid; unsaturated dibasic acid anhydride; Examples thereof include copolymers of styrene monomers and polyesters; epoxy resins. More preferred are styrene and (meth) acrylic acid copolymers, maleic acid copolymers, saturated or unsaturated polyester resins, and epoxy resins.
[0184]
Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile). ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or isoazo polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydro Peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, tris- (T-Butylperoxy) to Peroxide-based initiators such as lyazine, polymer initiators having a peroxide in the side chain, persulfates such as potassium persulfate and ammonium persulfate, and hydrogen peroxide are used.
[0185]
The polymerization initiator is preferably added in an amount of 0.5 to 20 parts by mass of the polymerizable monomer, and may be used alone or in combination.
[0186]
Moreover, in order to control molecular weight in this invention, you may add a well-known crosslinking agent and a chain transfer agent, As a preferable addition amount, it is 0.001-15 mass parts.
[0187]
In the present invention, any suitable stabilizer is used for the dispersion medium used in the production of the polymerization toner by emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, polymerization method using hetero-aggregation method, or the like. To do. For example, as an inorganic compound, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. As organic compounds, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and its salts, starch, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid-g-methacrylic acid) (Methyl-eu-methacrylic acid) copolymer and nonionic or ionic surfactants are used.
[0188]
In the case of using the emulsion polymerization method and the heteroaggregation method, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant are used. These stabilizers are preferably used in an amount of 0.2 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0189]
Among these stabilizers, when an inorganic compound is used, a commercially available one may be used as it is, but in order to obtain fine particles, the inorganic compound may be produced in a dispersion medium.
[0190]
Moreover, you may use 0.001-0.1 mass part surfactant for fine dispersion of these stabilizers. This is to promote the desired action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, lauric acid. Examples thereof include sodium, potassium stearate, calcium oleate and the like.
[0191]
The toner of the present invention can usually be used for one-component and two-component developers. When a non-magnetic toner containing no magnetic material is used as a one-component developer, there is a method in which a blade or a roller is used to forcibly frictionally charge with a developing sleeve, and the toner is deposited on the sleeve and conveyed. is there.
[0192]
The toner of the present invention may be used as a one-component developer composed only of toner (no carrier) or may be used as a two-component developer composed of toner and carrier. Since the toner of the present invention can be suitably used in a full-color image forming method, it can be suitably used as a two-component developer.
[0193]
Next, usable carriers when the present invention is used in two-component development will be described.
[0194]
When the 50% particle size of the carrier is less than 15 μm, carrier adhesion to the non-image area by particles on the fine particle side of the particle size distribution of the carrier may not be satisfactorily prevented. When the 50% particle size of the carrier is larger than 60 μm, the texture due to the rigidity of the magnetic brush does not occur, but the unevenness of the image due to the size may occur.
[0195]
In the present invention, examples of the metal compound particles used for the carrier core include magnetite or ferrite having magnetism represented by the following formula (1) or (2).
[0196]
MO ・ Fe ₂ O _Three ... (1)
M ・ Fe ₂ O _Four ... (2)
(In the formula, M represents a trivalent, divalent or monovalent metal ion.)
[0197]
M includes Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Ba, Pb, and Li can be mentioned, and these can be used alone or in plural.
[0198]
Specific examples of the metal compound particles having magnetism include, for example, magnetite, Zn—Fe ferrite, Mn—Zn—Fe ferrite, Ni—Zn—Fe ferrite, Mn—Mg—Fe ferrite, Ca— Examples thereof include iron-based oxides such as Mn—Fe ferrite, Ca—Mg—Fe ferrite, Li—Fe ferrite, and Cu—Zn—Fe ferrite.
[0199]
Furthermore, in the present invention, the metal compound particles used for the carrier core may be a mixture of the above magnetic metal compound and the following nonmagnetic metal compound.
[0200]
Examples of nonmagnetic metal compounds include Al. ₂ O _Three , SiO ₂ , CaO, TiO ₂ , V ₂ O _Five , CrO, MnO ₂ , Α-Fe ₂ O _Three , CoO, NiO, CuO, ZnO, SrO, Y ₂ O _Three And ZrO ₂ Is mentioned. In this case, one kind of metal compound can be used, but it is particularly preferable to use a mixture of at least two kinds of metal compounds. In that case, it is more preferable to use particles having similar specific gravity and shape in order to increase the adhesion to the binder resin and the strength of the carrier core particles.
[0201]
Specific examples of combinations include, for example, magnetite and hematite, magnetite and r-Fe. ₂ O _Three , Magnetite and SiO ₂ , Magnetite and Al ₂ O _Three , Magnetite and TiO ₂ Magnetite and Ca—Mn—Fe based ferrite, and magnetite and Ca—MgFe based ferrite can be preferably used. Among these, a combination of magnetite and hematite can be particularly preferably used.
[0202]
The binder resin for the carrier core particles used in the present invention is a thermosetting resin and is preferably a resin partially or wholly crosslinked three-dimensionally. As a result, the dispersed metal compound particles can be strongly bound, so that the strength of the carrier core can be increased, and the metal compound is hardly detached even in a large number of copies. As a result, it is easy to control the amount of adsorbed water within the range of the present invention.
[0203]
The method for obtaining the magnetic material-dispersed carrier core is not particularly limited to the method described below, but in the present invention, from a solution in which the monomer and the solvent are uniformly dispersed or dissolved, Production method of polymerization method in which particles are produced by polymerizing monomers, in particular, a magnetic substance with a sharp particle size distribution and a small amount of fine powder by applying a lipophilic treatment to the metal oxide dispersed in the carrier core particles A method of obtaining a dispersed resin carrier core is preferably used.
[0204]
In the present invention, in the case of a carrier used in combination with a small particle size toner having a weight average particle size of 4 to 10 μm in order to achieve high image quality, the carrier particle size is also reduced according to the particle size of the toner. The above-described manufacturing method is particularly preferable because a carrier with less fine powder can be manufactured regardless of the average particle diameter even if the carrier particle diameter is reduced.
[0205]
As the monomer used for the binder resin of the carrier core particle, a radical polymerizable monomer can be used. For example, styrene; styrene derivatives such as o-methyl styrene, m-methyl styrene, p-methoxy styrene, p-ethyl styrene, p-tertiary butyl styrene; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate Acrylates such as n-propyl acrylate, isobutyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methacrylic acid, methyl methacrylate , Ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, meta Methacrylic acid esters such as phenyl laurate, dimethylaminomethyl methacrylate, diethylaminoethyl methacrylate, benzyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide; methyl vinyl ether, ethyl vinyl ether , Propyl vinyl ether, n-butyl ether, isobutyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl ether, p-chlorophenyl ether, p-bromophenyl ether, p-nitrophenyl vinyl ether, p-methoxyphenyl vinyl ether And vinyl ethers; and diene compounds such as butadiene.
[0206]
These monomers can be used alone or in combination, and a suitable polymer composition can be selected so that preferable characteristics can be obtained.
[0207]
As described above, the binder resin of the carrier core particles is preferably three-dimensionally crosslinked. However, as a crosslinking agent for three-dimensionally crosslinking the binder resin, a polymerizable double bond is used. It is preferable to use a crosslinking agent having two or more per molecule. Examples of such cross-linking agents include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and 1,3-butylene glycol. Dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, penta Erythritol dimethacrylate, pentaerythritol tetramethacrylate, glycerol Alkoxy dimethacrylate, N, N-divinyl aniline, divinyl ether, and a divinyl sulfide and divinyl sulfone. These may be used by mixing two or more kinds as appropriate. The cross-linking agent can be mixed in advance with the polymerizable mixture, or can be appropriately added during the polymerization as necessary.
[0208]
Other binder resin monomers for carrier core particles include bisphenols and epichlorohydrin as starting materials for epoxy resins; phenols and aldehydes of phenolic resins; urea and aldehydes of urea resins; melamine and aldehydes.
[0209]
The most preferred binder resin is a phenolic resin. Examples of the starting material include phenol compounds such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcil, and p-tert-butylphenol, and aldehyde compounds such as formalin, paraformaldehyde, and furfural. A combination of phenol and formalin is particularly preferable.
[0210]
When these phenol resins or melamine resins are used, a basic catalyst can be used as a curing catalyst. As the basic catalyst, various catalysts used in the production of ordinary resole resins can be used. Specific examples include amines such as aqueous ammonia, hexamethylenetetramine, diethyltriamine, and polyethyleneimine.
[0211]
In the present invention, the metal compound contained in the carrier core is preferably oleophilic in order to sharpen the particle size distribution of the magnetic carrier particles and to prevent the metal compound particles from being detached from the carrier. . When forming carrier core particles in which a metal compound subjected to lipophilic treatment is dispersed, particles insolubilized in the solution are generated at the same time as the polymerization reaction proceeds from a liquid in which the monomer and solvent are uniformly dispersed or dissolved. At that time, it is considered that the metal oxide is taken in uniformly and at a high density inside the particles and has an effect of preventing aggregation of the particles and sharpening the particle size distribution. Furthermore, when a metal compound subjected to oleophilic treatment is used, it is not necessary to use a suspension stabilizer such as calcium fluoride, charging stability is inhibited due to the suspension stabilizer remaining on the carrier surface, and during coating Inhomogeneity of the coating resin and reaction inhibition when a reactive resin such as a silicone resin is coated can be prevented. In addition, it is easy to control the amount of adsorbed water within the scope of the present invention by eliminating the suspension stabilizer on the surface and eliminating the problems associated therewith.
[0212]
The oleophilic treatment is treated with an oleophilic agent which is an organic compound having one or more functional groups selected from epoxy groups, amino groups and mercapto groups, and a mixture thereof. Is preferred. In particular, an epoxy group is preferably used in order to easily achieve the range of the amount of adsorbed moisture of the present invention and to obtain a carrier having stable charge imparting ability.
[0213]
The magnetic metal oxide particles are preferably treated with a lipophilic treatment agent in an amount of 0.1 to 10 parts by weight, more preferably 0.2 to 6 parts by weight per 100 parts by weight of the magnetic metal oxide particles. It is preferable for enhancing the lipophilicity and hydrophobicity of the metal oxide particles.
[0214]
Examples of the lipophilic agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane, epichlorohydrin, and glycidol. And styrene- (meth) acrylic acid glycidyl copolymer.
[0215]
Examples of the lipophilic agent having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxydiethoxysilane, γ-aminopropyltriethoxysilane, and N-β (aminoethyl) -γ-amino. Propyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, ethylenediamine, ethylenetriamine, styrene- (meth) acrylic acid dimethylaminoethyl copolymer Combined and isopropyl tri (N-aminoethyl) titanate are used.
[0216]
Examples of the lipophilic agent having a mercapto group include mercaptoethanol, mercaptopropionic acid, and γ-mercaptopropyltrimethoxysilane.
[0217]
The resin that coats the surface of the carrier core is not particularly limited. Specifically, for example, acrylic resin such as polystyrene and styrene-acrylic copolymer, vinyl chloride, vinyl acetate, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, Polyvinyl pyrrolidone, petroleum resin, cellulose, cellulose derivative, novolak resin, low molecular weight polyethylene, saturated alkyl polyester resin, aromatic polyester resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyphenylene sulfide resin, poly Ether ketone resin, phenol resin, modified phenol resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, anhydrous male Unsaturated polyester, urea resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin , Furan resin, silicone resin, polyimide resin, polyamideimide resin, polyetherimide resin and polyurethane resin.
[0218]
Of these, silicone resins are preferably used from the viewpoint of adhesion to the core and prevention of spent. The silicone resin can be used alone, but is preferably used in combination with a coupling agent in order to increase the strength of the coating layer and control the charge to a preferable level. Furthermore, the coupling agent described above is preferably used as a so-called primer agent in which a part of the coupling agent is treated on the surface of the carrier core before coating the resin, and the subsequent coating layer is accompanied by a covalent bond. , It can be formed in a more adhesive state.
[0219]
Aminosilane is preferably used as the coupling agent. As a result, a positively charged amino group can be introduced on the surface of the carrier, and the toner can be favorably imparted with negative charging characteristics. Furthermore, the presence of amino groups activates both the lipophilic treatment agent that is preferably treated with the metal compound and the silicone resin, thereby further improving the adhesion between the silicone resin carrier core and simultaneously curing the resin. By promoting the above, a stronger coating layer can be formed.
[0220]
In the present invention, the used carrier was measured for physical properties by the following measuring method as required.
[0221]
The volume-based 50% particle size and particle size distribution of the carrier particles are measured by a laser diffraction particle size distribution analyzer (Hellos <HELOS) manufactured by SYNPATEC and equipped with a dry disperser (Rodos <RODOS>). >) Under the conditions of a feed air pressure of 3 bar and a suction pressure of 0.1 bar.
[0222]
In order to satisfactorily charge the toner of the present invention, the carrier particle size is preferably 50 to 60 μm, more preferably 25 to 50 μm, and even more preferably 30 to 40 μm, based on a volume basis of 50% particle size (D). preferable. Further, the content of particles having a particle size of 2/3 or less of the 50% particle size (2D / 3 ≧) is preferably 5% by volume or less, more preferably 0.1 to 5% by volume. good.
[0223]
The measurement of the magnetic properties of the carrier is performed using an oscillating magnetic field type magnetic property automatic recording device BHV-35 manufactured by Riken Denshi Co., Ltd. As a measurement, an external magnetic field of 1000 / 4π (kA / m) is created, and the magnetization strength at that time is obtained. Pack in a cylindrical plastic container so that the carrier particles do not move sufficiently, measure the magnetization moment in this state, measure the actual mass when the sample is put, and measure the magnetization strength ( Am ² / Kg).
[0224]
When measuring carrier physical properties from a two-component developer, the developer is washed with ion exchange water containing 1% of Contaminone N (surfactant) to separate the toner and the carrier, and then the above measurement is performed. .
[0225]
The specific resistance of the carrier is measured using a powder insulation resistance measuring instrument manufactured by Vacuum Riko Co., Ltd. The measurement conditions were as follows: a carrier left at 23 ° C. and 60% for 24 hours or more had a diameter of 20 mm (0.283 cm ² ) In a measuring cell of 120 g / cm ² Are measured with a load electrode of 500 mm and an applied voltage of 500V.
[0226]
The method for measuring the apparent density of the carrier is performed according to JIS-Z02504.
[0227]
Hereinafter, the image forming apparatus (image recording apparatus) of the embodiment will be specifically described. However, these do not limit the present invention at all.
[0228]
FIG. 1 is a schematic configuration model diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process, a contact charging method, a reversal development method, cleanerless, and a maximum sheet passing size of A3 size.
[0229]
(1) Overall schematic configuration of printer
a) Photosensitive drum
Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum). As shown in the layer configuration model diagram of FIG. 2, the photosensitive drum 1 has an undercoat layer 1b that suppresses light interference and improves the adhesion of an upper layer on the surface of an aluminum cylinder (conductive drum base) 1a. The photocharge generation layer 1c and the charge transport layer 1d are coated in order from the bottom.
[0230]
The photosensitive drum of the present invention is not limited to the above. Next, a typical configuration of the electrophotographic photosensitive member will be described with reference to FIGS. 3, 4, and 5. FIG.
[0231]
The photosensitive layer is composed mainly of an organic photoconductor. As the organic photoconductor, an organic photoconductive polymer such as polyvinyl carbazole or a low molecular weight organic photoconductive substance is used in a binder resin. There are things contained in.
[0232]
In the electrophotographic photosensitive member of FIG. 3, a photosensitive layer 17 is provided on a conductive support 16, and this photosensitive layer 17 includes a charge generation layer 19 in which a charge generation material 18 is dispersedly contained in a binder resin, and charge transport. It is a laminated structure of the layer 20. In this case, the charge transport layer 20 is laminated on the charge generation layer 19.
[0233]
In the electrophotographic photosensitive member of FIG. 4, unlike the case of FIG. 3, the charge transport layer 20 is laminated under the charge generation layer 19. In this case, the charge generation layer 19 may contain a charge transport material.
[0234]
In the electrophotographic photosensitive member of FIG. 5, a photosensitive layer 17 is provided on a conductive support 16, and the photosensitive layer 17 contains a charge generation material 18 and a charge transport material (not shown) in a binder resin. Has been.
[0235]
Among these, as shown in FIG. 3, a photoreceptor having a structure in which a charge generation layer 19 and then a charge transport layer 20 are laminated in this order from the conductive support 16 side is preferable in the present invention.
[0236]
As the conductive support 16, a metal such as aluminum or stainless steel, a cylindrical cylinder such as paper or plastic, a sheet or a film is used. In addition, these cylindrical cylinders, sheets, or films may have a conductive polymer layer or a resin layer containing conductive particles such as tin oxide, titanium oxide, and silver particles as necessary.
[0237]
An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided between the conductive support 16 and the photosensitive layer 17.
[0238]
The undercoat layer is formed to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect against electrical breakdown of the photosensitive layer. Is done. The film thickness is about 0.2 to 2 μm.
[0239]
Examples of the charge generating substance include bililium, thiopiorilium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzbilenequinone pigments, pyratron pigments, azo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanines, and quinocyanines.
[0240]
As the charge transport material, hydrazone compounds, pyrazoline compounds, styryl compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, polyarylalkane compounds, and the like can be used.
[0241]
The charge generation layer 19 is well dispersed by a method such as a homogenizer, an ultrasonic wave, a ball mill, a vibration ball mill, a sand mill, an attritor, or a roll mill together with the above-mentioned charge generation material in an amount of 0.5 to 4 times the binder resin and solvent. Then, it is formed by coating and drying. The thickness is preferably 5 μm or less, particularly preferably in the range of 0.01 to 1 μm.
[0242]
The charge transport layer 20 is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform, and carbon tetrachloride. Is used. When this solution is applied, for example, a coating method such as a dip coating method, a spray coating method, or a spinner coating method can be used, and drying is performed at a temperature in the range of 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C. 5 minutes to 5 hours, preferably 10 minutes to 2 hours, and the drying can be carried out under blast drying or static drying. The thickness of the generated charge transport layer is preferably 5 to 30 μm, particularly preferably 10 to 25 μm.
[0243]
Examples of the binder resin used to form the charge generation layer 19 and the charge transport layer 20 include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, and alkyd resin. And a resin selected from unsaturated resins and the like are preferable. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin or diallyl phthalate resin. In addition, the charge generation layer or the charge transport layer can contain various additives such as an antioxidant, an ultraviolet absorber, and a lubricant.
[0244]
b) Charging means
Reference numeral 2 denotes a contact charging device (contact charger) as charging means for uniformly charging the peripheral surface of the photosensitive drum 1, and this example is a charging roller (roller charger).
[0245]
The charging roller 2 holds both ends of the cored bar 2a rotatably by bearing members (not shown), and is urged toward the photosensitive drum by a pressing pressure spring 2e to the surface of the photosensitive drum 1. It is brought into pressure contact with a predetermined pressing force, and rotates following the rotation of the photosensitive drum 1. A pressure contact portion between the photosensitive drum 1 and the charging roller 2 is a charging portion (charging nip portion) a.
[0246]
A charging bias voltage of a predetermined condition is applied from the power source S1 to the metal core 2a of the charging roller 2, whereby the peripheral surface of the rotating photosensitive drum 1 is contact-charged to a predetermined polarity and potential. In this example, the charging bias voltage for the charging roller 2 is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac).
DC voltage: -500V
AC voltage; frequency f1000 Hz, peak-to-peak voltage Vpp 1400 V, and oscillating voltage superimposed with a sine wave. The peripheral surface of the photosensitive drum 1 is uniformly contact-charged to −500 V (dark potential Vd).
[0247]
The longitudinal length of the charging roller 2 is 320 mm, and the elastic layer 2b, the resistance control layer 2c, and the surface layer 2d are disposed below the cored bar (support member) 2a as shown in the layer configuration model diagram of FIG. It is a three-layer structure laminated sequentially. The elastic layer 2b is a foamed sponge layer for reducing charging noise, the resistance control layer 2c is a conductive layer for obtaining a uniform resistance as the whole charging roller, and the surface layer 2d is provided with a pinhole or the like on the photosensitive drum 1. This is a protective layer provided to prevent leakage even if there is a defect.
[0248]
Further details will be described.
[0249]
In FIG. 2, 2 is a charging member, 2a is a conductive support, 2b is an elastic layer, 2c is a resistance control layer, and 2d is a surface layer. The charging roller may be composed of an elastic layer 2b and a surface layer 2d without the resistance control layer 2c.
[0250]
For the conductive support 2a used in the present invention, metals such as iron, copper, stainless steel, aluminum and nickel can be used. Furthermore, these metal surfaces may be plated for the purpose of providing rust prevention and scratch resistance, but it is necessary not to impair the conductivity.
[0251]
In the charging roller 2, the elastic layer 2 b has appropriate elasticity to ensure good uniform adhesion of the charging roller 2 to the photoreceptor 1.
[0252]
The conductivity of the elastic layer 2b is adjusted by adding conductive particles such as carbon black or a conductive agent such as alkali metal salt and ammonium salt to an elastic material such as rubber. Elasticity is adjusted by the addition of process oil and plasticizer. Specific elastic materials for the elastic layer 2b include, for example, natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber. Examples include synthetic rubbers such as (BR), nitrile-butadiene rubber (NBR), and chloroprene rubber (CR), and resins such as polyamide resin, polyurethane resin, silicone resin, and fluororesin. Moreover, you may use the foam of the above-mentioned elastic material for the elastic layer 2b.
[0253]
The elastic layer has an electric resistance of 1 × 10 ^Three ~ 1x10 ^Ten It preferably has conductivity in the range of [Ωcm]. Further, since the film thickness depends on the diameter of the conductive support, it is not particularly limited.
[0254]
The surface layer 2d is often provided in order to prevent bleed-out of the plasticizer or the like in the elastic layer 2b to the surface of the charging roller, or to maintain the slidability and smoothness of the surface of the charging roller. The surface layer 2d is provided by coating or coating a tube.
[0255]
When the surface layer 2d is provided by coating, specific materials include polyamide resins, polyurethane resins, acrylic resins, fluororesins, silicone resins, and the like, as well as epichlorohydrin rubber, urethane rubber, chloroprene rubber, acrylonitrile rubber, etc. Is mentioned. As a coating method, a dip coating method, a roll coating method, a spray coating method, or the like is preferable.
[0256]
When the surface layer 2d is provided by covering a tube, specific materials include nylon 12, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin), PVDF (polyvinylidene fluoride), FEP ( And a thermoplastic elastomer such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide.
[0257]
The tube may be a heat-shrinkable tube or a non-heat-shrinkable tube. In order to impart appropriate conductivity to the surface layer 2d, conductive particles such as carbon black and carbon graphite, conductive metal oxides such as conductive titanium oxide, conductive zinc oxide, and conductive tin oxide are used. A conductive agent is used.
[0258]
The electric resistance of the surface layer is 1 × 10 ⁶ ~ 1x10 ¹⁴ The range is preferably [Ωcm]. The film thickness is preferably 2 to 500 μm. More preferably, it is 2 to 250 μm.
[0259]
The resistance control layer 2c is often provided to control the resistance of the charging member. Specific materials for the resistance control layer 2c include resins such as polyamide resin, polyurethane resin, fluororesin, and silicone resin, as well as epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber. For the purpose of resistance adjustment, the resistance control layer 2c also has conductive particles such as carbon black and carbon graphite, conductive metal oxides such as conductive titanium oxide, conductive zinc oxide, and conductive tin oxide, or alkali metal salts. In addition, a conductive agent such as ammonium salt can be dispersed. The resistance control layer 2c is also provided by coating or coating a tube.
[0260]
The electric resistance of the resistance control layer is 1 × 10 ⁶ ~ 1x10 ^Ten The range is preferably [Ωcm].
[0261]
The film thickness is preferably 10 to 1000 μm. More preferably, it is 10 to 750 μm.
[0262]
The volume resistivity in the present invention is measured according to JIS K 6911.
[0263]
In FIG. 2, reference numeral 2f denotes a charging roller cleaning member, which is a flexible cleaning film in this example. The cleaning film 2f is arranged in parallel to the longitudinal direction of the charging roller 2 and fixed at one end to a support member 2g that reciprocates a certain amount in the longitudinal direction. It is arranged to form a contact nip. The support member 2g is driven to reciprocate by a certain amount in the longitudinal direction via a gear train by a drive motor of the printer, and the charging roller surface layer 2d is rubbed with the cleaning film 2f. As a result, contaminants (fine powder toner, external additives, etc.) on the charging roller surface layer 2d are removed.
[0264]
c) Information writing means
Reference numeral 3 denotes exposure as information writing means for forming an electrostatic latent image on the surface of the charged photosensitive drum 1. There are a method using an LED array, a method using a semiconductor laser, a method using a liquid crystal shutter array, and the like.
[0265]
This example is a laser beam scanner using a semiconductor laser. A laser beam modulated in response to an image signal sent from a host device such as an image reading device to the printer side is output, and the uniformly charged surface of the rotating photosensitive drum 1 is scanned by a laser scanning exposure L (image) at an exposure position b. Exposure). Due to the laser scanning exposure L, the potential of the surface of the photosensitive drum 1 irradiated with the laser light is lowered, and electrostatic latent images corresponding to the scanned and exposed image information are sequentially formed on the surface of the rotating photosensitive drum 1. Go.
[0266]
d) Development means
Reference numeral 4 denotes a developing device (developer) as developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 to visualize the electrostatic latent image. This example is a two-component magnetic brush developing system. A reversal developing device.
[0267]
4a is a developing container, 4b is a non-magnetic developing sleeve, and this developing sleeve 4b is rotatably arranged in the developing container 4a with a part of its outer peripheral surface exposed to the outside. 4c is a non-rotating fixed magnet roller inserted in the developing sleeve 4b, 4d is a developer coating blade, 4e is a two-component developer contained in the developing container 4a, and 4f is disposed on the bottom side in the developing container 4a. The provided developer stirring member, 4g, is a toner hopper and contains replenishing toner.
[0268]
Thus, the surface of the rotating developing sleeve 4b is coated with a phenol resin in which carbon and graphite are dispersed as a thin layer, and the toner contained in the developer conveyed to the developing section c is subjected to an electric field by a developing bias by the photosensitive drum 1. The electrostatic latent image is developed as a toner image by selectively adhering to the surface corresponding to the electrostatic latent image. In the case of this example, the toner adheres to the exposed bright portion of the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed.
[0269]
The developer thin layer on the developing sleeve 4b that has passed through the developing section c is returned to the developer reservoir in the developing container 4a with the subsequent rotation of the developing sleeve.
[0270]
In order to maintain the toner concentration of the two-component developer 4e in the developing container 4a within a predetermined substantially constant range, the toner concentration of the two-component developer 4e in the developing container 4a is adjusted by, for example, an optical toner concentration sensor (not shown). The toner hopper 4g is driven and controlled according to the detected information, and the toner in the toner hopper is supplied to the two-component developer 4e in the developing container 4a. The toner supplied to the two-component developer 4e is stirred by the stirring member 4f.
[0271]
e) Transfer means / fixing means
Reference numeral 5 denotes a transfer device, and this example is a transfer roller. The transfer roller 5 is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and the pressure nip portion is a transfer portion d. A transfer material (a member to be transferred, a recording material) P is fed to the transfer portion d from a paper feeding mechanism portion (not shown) at a predetermined control timing.
[0272]
The transfer material P fed to the transfer part d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5, and during that time, the negative polarity that is the normal charging polarity of the toner from the power source S 3 is transferred to the transfer roller 5. In this example, the positive polarity transfer bias having the reverse polarity is applied with +2 kV, so that the toner image on the surface of the photosensitive drum 1 is sequentially electrostatically transferred onto the surface of the transfer material P that is nipped and conveyed by the transfer portion d. To go.
[0273]
The transfer material P that has received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the rotary photosensitive drum 1 and is conveyed to the fixing device 6 (for example, a heat roller fixing device) to receive the toner image fixing process. Output as an image formed product (print, copy).
[0274]
(2) Cleanerless system and toner charge control
The printer of this example is cleanerless, and does not include a dedicated cleaning device that removes a small amount of transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image to the transfer material P. After the transfer, the untransferred toner on the surface of the photosensitive drum 1 is carried to the developing unit c through the charging unit a and the exposure unit b as the photosensitive drum 1 continues to rotate, and simultaneously developed (collected) by the developing device 4. (Cleanerless system).
[0275]
In this embodiment, as described above, the developing sleeve 4b of the developing device 4 is rotated in the developing portion c in a direction opposite to the traveling direction of the surface of the photosensitive drum 1, which is the transfer plate toner on the photosensitive drum 1. It is advantageous for recovery.
[0276]
Since the untransferred toner on the surface of the photosensitive drum 1 passes through the exposure part b, the exposure process is performed from the untransferred toner. However, since the amount of the untransferred toner is small, no significant influence appears.
[0277]
However, as described above, the transfer residual toner includes a mixture of normal polarity, reverse polarity (reversal toner), and low charge amount, among which reverse toner and toner with low charge amount. Adhering to the charging roller 2 when passing through the charging portion a causes the charging roller to be contaminated with toner more than allowable, resulting in a charging failure.
[0278]
Further, in order to effectively develop and collect the transfer residual toner on the surface of the photosensitive drum 1 by the developing device 3, the charging polarity of the transfer residual toner on the photosensitive drum carried to the developing unit c is a normal polarity. In addition, the charge amount needs to be a charge amount of toner that can develop the electrostatic latent image on the photosensitive drum by the developing device. Reversal toner and toner with an inappropriate charge amount cannot be removed and collected from the photosensitive drum to the developing device, causing a defective image.
[0279]
Therefore, in the present embodiment, the charging polarity of the residual toner after transfer is aligned with the negative polarity that is the normal polarity at the position downstream of the transfer portion d in the photosensitive drum rotation direction and upstream of the charging portion a. Toner (developer) charge amount control means 7 is provided.
[0280]
By aligning the charging polarity of the transfer residual toner to the negative polarity that is the normal polarity, the photosensitive drum 1 is charged when the surface of the photosensitive drum 1 is charged from above the transfer residual toner in the charging unit a located further downstream. Therefore, the transfer residual toner is prevented from adhering to the charging roller 2.
[0281]
Next, recovery of transfer residual toner in the development process will be described.
[0282]
The developing device 4 is as described above, and is a cleanerless system that cleans the transfer residual toner when developing.
[0283]
The toner charge amount for collecting the transfer residual toner on the photosensitive drum 1 to the developing device 4 is an absolute charge amount smaller than the absolute value of the charge amount when the developer charge amount control means is charged. It is necessary to make it. This is so-called neutralization, and if the charge amount of the transfer residual toner is high, the affinity with the drum is superior, and the toner is not collected by the developing device 4 and causes an image defect.
[0284]
However, as described above, in order to prevent the toner from adhering to the charging roller 2, in order to collect the transfer residual toner charged to the negative polarity by the toner charge amount control means 7 in the developing device 4, the charge removal is performed. There is a need to do. The charge removal is performed by the charging unit a. That is, as described above, an AC voltage of 1000 Hz and 1400 V is applied to the charging roller 2, whereby the transfer residual toner is subjected to AC neutralization. Further, by adjusting the AC voltage applied to the charging roller 2, the toner charge amount after passing through the charging portion a can be adjusted by AC neutralization. In the developing step, the transfer residual toner on the photosensitive drum 1 where the toner should not be developed is collected by the developing device 4 for the above reason.
[0285]
Thus, the transfer residual toner tribo on the photosensitive drum 1 carried from the transfer portion d to the charging portion a is charged by the toner charge amount control means 7 so as to have the normal polarity and the negative polarity, thereby charging the transfer residual toner. While the photosensitive drum 1 is charged to a predetermined potential by the charging roller 2 while preventing the toner from adhering to the roller 2, the transfer residual toner charged to the negative polarity having the normal polarity by the toner charge amount control means 7 is simultaneously charged. By controlling the charge amount to an appropriate charge amount that can develop the electrostatic latent image on the photosensitive drum by the developing device 4, the transfer residual toner can be efficiently collected by the developing device. It is possible to provide an image forming apparatus that does not have a defective image and takes advantage of the cleanerless system.
[0286]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the examples.
[0287]
A method for manufacturing the carrier will be described below.
[0288]
(Magnetic carrier production example 1)
After mixing and dispersing phenol / formaldehyde monomer (50:50) in an aqueous medium, 700 parts of 0.24 μm magnetite particles and 300 parts of 0.59 μm hematite particles surface-treated with a titanium coupling agent with respect to the monomer weight. Is uniformly dispersed, the monomer is polymerized while adding ammonia as appropriate, and the magnetic particle-containing spherical magnetic resin carrier core 1 (average particle diameter 32 μm, saturation magnetization 37 Am) ² / Kg).
[0289]
Meanwhile, 20 parts of toluene, 20 parts of butanol, 20 parts of water, and 40 parts of ice are placed in a four-necked flask and stirred with CH. _Three SiCl _Three 15 mol and (CH _Three ) ₂ SiCl ₂ After adding 40 parts of a mixture with 10 mol and further stirring for 30 minutes, a condensation reaction was carried out at 60 ° C. for 1 hour. Thereafter, the siloxane was thoroughly washed with water and dissolved in a toluene-methyl ethyl ketone-butanol mixed solvent to prepare a silicone varnish having a solid content of 10%.
[0290]
To this silicone varnish, 2.0 parts of ion-exchanged water and 2.0 parts of the following curing agent (2), 1.0 part of the following aminosilane coupling agent (11) and 5 parts per 100 parts of the siloxane solid form 0.0 parts of the lower silane coupling agent (18) was added at the same time to prepare a carrier coating solution I. This solution I was applied to 100 parts of the carrier core material with a coating machine (Okada Seiko Co., Ltd .: Spiracoater) so that the resin coating amount would be 1 part, whereby a coated carrier 1 was obtained.
[0291]
This carrier has a 50% particle size of 34 μm, a content of particles having a particle size of 2/3 or less of the 50% particle size (2D / 3 ≧) is 3.2% by volume, and the value of SF-1 is 109.
[0292]
Furthermore, the specific resistance is 8 × 10 ¹³ Ωcm, saturation magnetization is 41 Am ² / Kg.
[0293]
[Chemical 6]

[0294]
(Magnetic carrier production example 2)
MgO 15 parts, MnO 10 parts, Fe ₂ O _Three After atomization using 75 parts, water was added and granulated, followed by firing at 1200 ° C., a 50% diameter by volume average of 32 μm, and a particle size of 2/3 or less of the 50% particle size ( A ferrite carrier core material having a content of 2D / 3 ≧) particles of 8.4% by volume was obtained.
[0295]
The core material was coated with a resin in the same manner as in Production Example 1 to obtain a coated carrier 4.
[0296]
The SF-1 value of this carrier was 126.
[0297]
Furthermore, the specific resistance is 4 × 10 ¹² Ωcm, saturation magnetization is 56 Am ² / Kg.
[0298]
Next, a method for manufacturing the charging roller will be described.
[0299]
(Production example 1 of charging roller)
With respect to 100 parts by mass of EPDM, 39 parts by mass of conductive carbon black, 51 parts by mass of paraffin oil, an appropriate amount of a foaming agent, a crosslinking agent and other compounding agents were added and kneaded to prepare a conductive compound 1. Next, the compound was vulcanized and formed on a stainless steel core having a diameter of 6 mm, and then the outer diameter was polished to produce an elastic layer 1 which is a foam having a thickness of 3 mm.
[0300]
Next, 15.5 parts by mass of conductive carbon black was blended with 10 parts by mass of an ether-based thermoplastic urethane elastomer (Asker C hardness: 62), and melt kneaded at 182 ° C. for 9 minutes using a pressure kneader. Further, after cooling, the mixture was pulverized by a pulverizer and then pelletized using a single screw extruder.
[0301]
This pellet was used to obtain a seamless tube having an inner diameter of 10.5 [mm] and a wall thickness of 500 [μm] using an extruder. This tube is hereinafter referred to as tube A.
[0302]
Further, using the same pellet, a disk-like sheet having a diameter of 5 mm and a thickness of 3 mm was produced by hot pressing, and immersed in paraffin oil which is a softening agent for the elastic layer 1 for 7 days. When the weight change rate and the volume resistivity before and after being left to stand were measured with this sheet, the weight change rate was 0.03%, and the volume resistivity was 1.9 × 10 before leaving. ⁶ Ωcm, 2.0 × 10 after standing ⁶ There was almost no change with Ωcm.
[0303]
Separately, 100 parts by mass of conductive carbon black of 100 parts by mass of a thermoplastic elastomer (Asker C hardness; 62) in which an ethylene butylene rubber molecular chain is covalently bonded to one end of a polystyrene molecular chain and the other end of an olefin crystal. And kneaded at 200 ° C. for 10 minutes using a pressure kneader. Further, after cooling, the mixture was pulverized by a pulverizer and then pelletized using a single screw extruder. Furthermore, a seamless tube having an inner diameter of 11.5 [mm] and a wall thickness of 200 [μm] was obtained from the pellets using an extruder. This tube is hereinafter referred to as tube B.
[0304]
Subsequently, air was blown into the tube A to expand the outer diameter, the elastic layer 1 was inserted to cover the tube, and then the tube B was coated on the outside in the same manner to obtain the charging roller 1.
[0305]
Each characteristic of the obtained charging roller 1 was as follows.
[0306]
Electrical resistance value;
Low temperature and low humidity environment (temperature 15 ° C, humidity 10%, L / L environment) 1.2MΩ
High temperature and high humidity environment (temperature 32.5 ° C, humidity 80%, below H / H environment) 1.0MΩ
Surface hardness: 62 degrees (Asker C)
[0307]
The electrical resistance value is obtained by tightly winding an aluminum foil having a width of 10 mm around the outer periphery of the charging roller, applying a DC voltage of 250 V between the metal core and the aluminum foil, and using an ohmmeter HIOKI 3119 DIGITAL MΩ HITESTER (manufactured by Hioki Electric). It is a measured value.
[0308]
The surface hardness (Asker C) is measured using an Asker C rubber hardness meter (manufactured by Kobunshi Keiki Co., Ltd.), and a numerical value is obtained with an average of 5 points. In addition, the measurement is performed with a 500 g load on one side.
[0309]
(Production Example 1 of Silica Fine Powder (A))
Silica was produced by a dry silica production method as described below. Open the flammable gas supply pipe to supply oxygen gas to the burner, ignite the ignition burner, then open the flammable gas supply pipe to supply hydrogen gas to the burner to form a flame, and form tetrachloride Silicon was gasified with an evaporator and supplied to cause a flame hydrolysis reaction, and the produced silica powder was recovered. Using 100 parts by mass of the obtained silica fine powder, this was put in a mixer and stirred under a nitrogen atmosphere to 50 mm. ² 20 parts by mass of / s dimethyl silicone oil was added dropwise, heated and stirred at 300 ° C. for 1 hour, and then cooled to prepare silica fine powder (A-1). It is described in Table 1.
[0310]
(Silica fine powder (A) Production Example 2 11 )
After adjusting the raw material silicon tetrachloride gas amount, hydrogen gas and oxygen gas amount, silica concentration and residence time in the flame to obtain the silica base, various hydrophobization treatments were performed, and silica fine powder (A-2) ~ (A- 11 ). It is described in Table 1.
[0311]
(Silica Fine Powder (B) Production Examples 1 to 9 )
As with the silica fine powder (A), after adjusting the amount of raw material silicon tetrachloride gas, hydrogen gas and oxygen gas, the silica concentration in the flame and the residence time to obtain the silica base, various hydrophobization treatments were performed. Silica fine powder (B-1) to (B- 9 ). It shows in Table 2.
[0312]
[Table 1]

[0313]
[Table 2]

[0314]
Hereinafter, a toner manufacturing method will be described.
[0315]
(Toner Production Example 1)
The cyan toner used in the present invention was prepared as follows. 910 parts by mass of ion-exchanged water and 1 part by mass of polyvinyl alcohol are added to a 2 liter four-necked flask equipped with a high-speed agitator TK-homomixer, the number of revolutions is adjusted to 12,000 revolutions, and the mixture is heated to 60 ° C. Dispersant system.
[0316]
On the other hand, the dispersoid system is
164 parts by mass of styrene monomer
36 parts by mass of n-butyl acrylate monomer
9 parts by mass of phthalocyanine pigment
(C.I. Pigment Blue 15: 3)
10 parts by weight of saturated polyester resin
(Polycondensation product of bisphenol A and terephthalic acid, acid value of 10,
Glass transition point 70 ° C)
t-Butyl salicylic acid metal salt 4 parts by mass
Divinylbenzene 0.15 parts by mass
Low softening point material 30 parts by mass
(Ester wax Mw = 1200, Mn = 750, Mw / Mn = 1.6)
After the mixture was dispersed for 3 hours using an attritor, a dispersion added with 4 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was put into the dispersion medium. The granulation was continued for 10 minutes while maintaining the rotation speed. Thereafter, the stirrer was changed from the high-speed stirrer to the propeller stirring blade, the internal temperature was raised to 62 ° C., and polymerization was continued at 50 revolutions for 10 hours.
[0317]
After completion of the polymerization, the slurry was cooled, washed with water and dried to obtain cyan particles. Viscosity of 50 mm with respect to 100 parts by mass of the obtained cyan particles ² Silica fine powder (A-1) (average primary particle size 22 nm, BET 82 m) subjected to hydrophobization treatment with polydimethylsiloxane of / s and subjected to pulverization treatment and classification treatment and particle size adjustment after treatment. ² / G) is 0.5 parts by mass, the viscosity is also 50 mm ² / S fine silica powder (B-1) hydrophobized with polydimethylsiloxane (average primary particle size 9 nm, BET 140 m ² / G) 0.5 parts by mass, and fine alumina powder hydrophobized with isopropyltrimethoxysilane (average primary particle size 40 nm, BET 110 m ² / G) was added in an amount of 0.5 parts by mass, and uniformly diffused using a Henschel mixer manufactured by Mitsui Mining Co., Ltd. to obtain cyan toner (1).
[0318]
When the particle size distribution of the obtained cyan particles was measured with a Coulter counter, the volume average diameter was 6.1 μm. A toner configuration table is shown in Table 3.
[0319]
<Toner Comparative Production Example 1>
In Toner Production Example 1, 0.1 M Na at the time of production of the aqueous medium _Three PO _Four The amount of aqueous solution used was 600 parts, the number of revolutions of the Claire mixer at the time of granulation of the polymerizable monomer composition was 14,000 rpm, and the classification conditions of the multistage division classifier at the time of classification were changed, respectively. A comparative cyan toner (comparative toner 1) having a mass average particle diameter of 3.3 μm was obtained using the same method as in Production Example 1 except that the total amount added was 1.8 parts by mass.
[0320]
<Toner Comparative Production Example 2>
In Toner Production Example 1, 0.1 M Na at the time of production of the aqueous medium _Three PO _Four The amount of aqueous additive used is 190 parts, the number of revolutions of the Claire mixer at the time of granulation of the polymerizable monomer composition is 4300 rpm, the classification conditions of the multi-stage division classifier at the time of classification are changed, and the amount of external additives added In total amount 1.4 A comparative cyan toner (Comparative Toner 2) having a mass average particle diameter of 10.6 μm was obtained using the same method as in Production Example 1 except that the amount was changed to parts by mass.
[0321]
<Toner Production Example 2>
In Toner Production Example 1, 0.1 M Na at the time of production of the aqueous medium _Three PO _Four The amount of aqueous additive used is 530 parts, the number of revolutions of the Claire mixer at the time of granulation of the polymerizable monomer composition is 12000 rpm, the classification conditions of the multistage division classifier at the time of classification are changed, and the amount of external additives added 1 in total 5 mass Part A cyan toner (toner 2) having a mass average particle diameter of 4.2 μm was obtained in the same manner as in Production Example 1 except that
[0322]
<Toner Production Example 3>
In Toner Production Example 1, 0.1 M Na at the time of production of the aqueous medium _Three PO _Four The amount of the aqueous solution used is 280 parts, the number of rotations of the Claire mixer at the time of granulation of the polymerizable monomer composition is 5550 rpm, the classification conditions of the multistage division classifier at the time of classification are changed, and the addition amount of the external additive 1 in total 5 mass Part A cyan toner (toner 3) having a mass average particle diameter of 9.3 μm was obtained in the same manner as in Production Example 1 except that
[0323]
<Toner Production Examples 4 to 18, 21>
Table 3 shows fine powders obtained by changing the production methods such as the hydrophobization method, the crushing method, and the classification method so that the cyan particles in Production Example 1 have the physical properties shown in Tables 1 and 2, respectively. Cyan toners (4) to (18) were obtained by external addition with the structure shown in FIG.
[0324]
<Toner Comparative Production Examples 3 to 11>
For the cyan particles in Production Example 1, externally added fine powders obtained by changing the production method such as the hydrophobization method, the crushing method, and the classification method so as to have the physical properties shown in Tables 1 and 2, respectively. Thus, comparative cyan toners (3) to (11) were obtained.
[0325]
<Toner Production Example 19>
Styrene-2-ethylhexyl acrylate-divinylbenzene copolymer
(Glass transition point 65 ° C.) 100 parts by mass
7 parts by weight of phthalocyanine pigment
(C.I. Pigment Blue 15: 3)
Saturated polyester resin 5 parts by mass
(Condensation product of bisphenol A and terephthalic acid, acid value 10
Glass transition point 65 ° C)
Dialkyl salicylic acid metal compound 1 part by mass
Low softening point material 8 parts by mass
(Paraffin wax Mw = 1200, Mn = 750, Mw / Mn = 1.6)
The above mixture was premixed with a Henschel mixer, melt-kneaded at a temperature of 130 ° C. with a twin-screw extruder kneader, cooled, coarsely pulverized with a hammer mill, and then pulverized with an air jet fine pulverizer. This was classified to obtain cyan particles.
[0326]
At this time, the average circularity of the particles was 0.940.
[0327]
The cyan particles were externally added in the same manner as in Production Example 1 to obtain cyan toner (19).
[0328]
<Toner Production Example 20>
The cyan particles in Production Example 19 were subjected to spheronization using a surface treatment apparatus of a type in which blades rotate and mechanically processed to obtain cyan particles.
[0329]
At this time, the average circularity of the particles was 0.955.
[0330]
The cyan particles were externally added in the same manner as in Production Example 1 to obtain cyan toner (20).
[0331]
<Toner Production Examples 22 to 24>
Production Example 1 except that a magenta colorant (CI Pigment Red 122), a yellow colorant (CI Pigment Yellow 93), or a black colorant (grafted carbon black) is used as the colorant. Similarly, magenta toner (22), yellow toner (23) and black toner (24) were prepared.
[0332]
[Table 3]

[0333]
[Table 4]

[0334]
Example 1
Cyan two-component developer 1 was prepared by mixing cyan toner 1 and coat carrier 1 at a toner concentration of 8%.
[0335]
Next, a developing device of a commercially available copying machine CP2150 (manufactured by Canon) was modified as shown in FIG. 2, and a developing sleeve having a φ16 mm SUS sleeve adjusted to a surface shape Rz = 9.0 by sandblasting was used. did.
[0336]
In this example, toner charging control means is provided, and the applied voltage is -800V.
[0337]
A charging roller 1 is used as the charging member. The charging roller is urged in the direction of the photosensitive drum and is brought into pressure contact with the surface of the photosensitive drum with a predetermined pressing force, and is rotated by the rotation of the photosensitive drum. A pressure contact portion between the photosensitive drum and the charging roller is a charging portion (charging nip portion). In addition, an intermediate transfer belt made of polyimide was mounted, and the secondary transfer copier was modified.
[0338]
Further, in this example, the charging bias voltage for the charging roller is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac).
[0339]
More specifically,
DC voltage: -500V
AC voltage; frequency f1000 Hz, peak-to-peak voltage Vpp 800 V, and oscillating voltage on which a sine wave is superimposed. The peripheral surface of the photosensitive drum 1 is uniformly contact-charged to −500 V (dark potential Vd).
[0340]
The cleaning unit is removed, the development contrast is set to 250 V, the reversal contrast with fog is set to −150 V, a development bias having a discontinuous AC electric field is applied, and the above-described cyan two-component developer 1 is used. .5 ° C./85% RH) and low temperature and low humidity (15 ° C./10% RH), using an original document with an image area ratio of 10%, 50,000 sheets were continuously copied to produce an image. The results are shown in Tables 5 and 6.
[0341]
[Developability evaluation method]
(Image density change)
The image density is measured with a color reflection densitometer (for example, Color reflection density X-RITE 404 Amanufactured by X-Rite Co.).
[0342]
Evaluation is based on the difference between the initial density and the density after endurance of 50,000 sheets.
A: 0.05 or less
B: more than 0.05 and 0.1 or less
C: More than 0.1 and 0.2 or less
D: More than 0.2 and 0.3 or less
E: more than 0.3 and 0.4 or less
F: More than 0.4 and 0.5 or less
G: Over 0.5
[0343]
(Measurement of fog)
The fog was measured using a REFECTOMETER MODEL TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.) and calculated according to the following formula. A smaller fog value is better.

A: 0.6 or less
B: More than 0.6 and 1.1 or less
C: More than 1.1 and 1.6 or less
D: More than 1.6 and 2.0 or less
E: More than 2.0 and 3.0 or less
F: Over 3.0 and below 4.0
G: Over 4.0
[0344]
(Charge amount change)
The change in charge amount was evaluated based on the following evaluation criteria for the amount of change in the charge amount value after the end of durability of the developer in the developer container and after the passage of 50,000 sheets.
A: Change amount is 5% or less
B: Change amount exceeds 5% and 10% or less
C: Change amount exceeds 10% and 15% or less
D: Change amount exceeds 15% and 20% or less
E: Change amount exceeds 20% and 25% or less
F: The change amount exceeds 25% and is 30% or less
G: Change amount exceeds 3%
[0345]
(Charging roller dirty)
The charging roller contamination was evaluated based on the following evaluation criteria by visually observing the roller surface (also using a 50 × magnifier), further observing image defects.
A: Defects are not recognized at all on the roller surface and the image in the magnifier observation.
B: Some dirt is observed on the roller surface only in the latter half of the endurance observation, but it cannot be visually confirmed and does not appear in the image.
C: Stain is slightly observed on the roller surface in the second half of the endurance observation in the magnifying glass and is a level that can be recognized visually, but does not appear in the image. .
D: Slight dirt on the roller surface in the latter half of durability, loupe observation and visual observation, slight unevenness in the image, and a problem in practical use.
E: Many stains are observed on the roller surface in the latter half of durability, loupe observation and visual observation, and the image is considerably uneven, which is unacceptable for practical use.
F: In the latter half of the endurance, the roller surface is visually stained without observing the loupe, and the image is noticeably uneven, and cannot be used.
G: From the first half of the durability, the roller is dirty and the image is uneven and cannot be completely used.
[0346]
(Transfer efficiency)
As for the transfer efficiency, the ratio of the toner mass transferred onto the paper to the toner mass developed on the photosensitive member under the N / N condition using the image forming apparatus shown in FIG. Based on the evaluation.
A: 95% or more.
B: More than 90% and less than 95%.
C: More than 80% and less than 90%.
D: More than 70% and less than 80%.
E: More than 60% and less than 70%.
F: More than 50% and less than 60%.
G: 50% or less.
[0347]
(Solid uniformity)
The solid image on the obtained transfer paper was evaluated based on the following evaluation criteria because of the maximum and minimum values of the density at five points.
A: 0.05 or less
B: more than 0.05 and 0.1 or less
C: More than 0.1 and 0.15 or less
D: More than 0.15 and 0.2 or less
E: More than 0.2 and 0.25 or less
F: more than 0.25 and 0.3 or less
G: Over 0.3
[0348]
(Drum fusion)
The drum fusion was evaluated based on the following evaluation criteria by visually observing the drum surface and further observing image defects.
A: No drum fusion
B: Almost no drum fusion
C: Level where there is some drum fusion but no problem in actual use
D: Drum fused in the second half of the endurance, which may contaminate the image
E: Drum fusing from the first half of the endurance, which may contaminate the image
F: Remarkable drum fusion occurred
G: Drum fusion is severe and unusable in actual use.
[0349]
(Line glue / solid glue ratio)
It is calculated from the amount of paste per unit area of the unfixed image transferred on the paper. The amount of solid image with an image density of 1.4 and the amount of paste on a 0.5 mm wide vertical line (a direction parallel to the transfer material discharge direction) obtained under the same development conditions are measured and determined by the following equation.
Line paste amount (mg / cm ² ) / Paste amount of solid image (mg / cm ² )
[0350]
(image quality)
In durability tests under N / L and H / H environments, the gradation, highlight uniformity, fine line reproducibility, and image density were evaluated comprehensively according to the following evaluation items with reference to the original document. .
A: Pretty high image quality
B: Good image quality
C: The image quality is at an acceptable level
D: Level of image quality is slightly worse and is a complaint to strict users
E: It is a bad level and a problem in practical use.
F: It is quite bad and cannot be used.
G: Bad enough to be unrecognizable as a character
[0351]
(Toner scattering)
The amount of toner scattered in the machine after 30,000 sheets were imaged in an H / H environment was visually evaluated based on the following criteria.
A: No toner scattering
B: No toner scattering
C: Level where there is some toner scattering but no problem in actual use
D: Toner scatters and may contaminate the image in the second half of durability
E: Toner scatters and may contaminate image from the first half of durability
F: Remarkable toner scattering occurs
G: Toner scattering is severe with toner and carrier separated, and cannot be used in actual use.
[0352]
(9) Fixability evaluation
A CP2150 machine obtains an unfixed image having the maximum copy density and a density of 0.5. This is subjected to a fixing test at 165 ° C. using a CP2150 externally driven fixing device. Evaluation is performed as follows.
[0353]
(A) The solid black portion (maximum image density) is measured on the image density (Di max) after fixing, and then on two Lenz Cleaning Paper “dasper (R)” (Ozu Paper Co., Ltd.). A weight of 200 g is applied, the image is rubbed 10 times, and the image density Dm max after the rub is measured. The following judgment is made with the value of the following rubbing density reduction rate dv max.
Evaluation rank
A: Density reduction rate 0% or more and less than 2.5%
B: 2.5% or more and less than 5%
C: 5% or more and less than 10%
D: 10% or more and less than 20%
E: 20% or more and less than 30%
F: 30% or more and less than 50%
G: 50% or more
[0354]
(Examples 2 to 24 and Comparative Examples 1 to 11)
In Example 1, the same test was performed with the configurations shown in Tables 5 and 6. The result is shown.
[0355]
(Example 25)
An image evaluation result of cyan toner when image evaluation is performed with a two-component full color system is shown.
[0356]
(Example 26)
An evaluation result of cyan toner when an image evaluation of 8000 sheets was performed with a Canon LBP CP660 is shown.
[0357]
[Table 5]

[0358]
[Table 6]

[0359]
【The invention's effect】
In the toner of the present invention, in the secondary transfer system using the intermediate transfer member, the particle size of the external additive to be externally applied to the toner surface is set to a predetermined distribution, and the external additive is subjected to a hydrophobic treatment. Therefore, the member and the photosensitive drum are hardly contaminated or damaged, and even when a large number of sheets are continuously printed, an image forming method with stable image density and excellent durability stability without fogging can be obtained.
[0360]
Furthermore, in an image forming apparatus using a charging roller having a conductive elastic layer with a specified surface hardness, the image density is stable even when a large number of continuous prints are made, and the cleanerless has excellent durability and stability without fog. An image forming method of the type is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram illustrating an example of an image forming apparatus that can be applied to the present invention.
FIG. 2 is a schematic explanatory diagram illustrating an example of a charging roller that can be applied to the present invention.
FIG. 3 is a schematic explanatory view showing an example of an electrophotographic photosensitive member that can be applied to the present invention.
FIG. 4 is a schematic explanatory view showing another example of an electrophotographic photosensitive member that can be applied to the present invention.
FIG. 5 is a schematic explanatory view showing another example of an electrophotographic photosensitive member that can be applied to the present invention.
FIG. 6 is a schematic explanatory view showing still another image forming apparatus capable of performing the image forming method applicable to the present invention.

Claims (28)

Electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, information writing means for forming an electrostatic latent image on the charged electrostatic latent image carrier, and developer in the developing unit Developing means for visualizing the electrostatic latent image by supplying toner to the electrostatic latent image by the action of the electric field between the developer carrying body and the electrostatic latent image carrying body that are uniformly carried by the regulating member, and the visualized toner image In an image forming method comprising: a transfer unit that transfers onto a transfer material via an intermediate transfer member; and a fixing unit that heat-contacts and presses the toner image on the transfer material.
The toner is a toner having at least toner particles and an external additive,
The external additive has at least two types of silica fine powders (A) and (B) treated with a silane coupling agent and / or silicone oil,
The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
18 ≦ r (A) ≦ 38 nm, 6 ≦ r (B) ≦ 14 nm
And
In the volume average particle size distribution by a laser diffraction type particle size distribution meter, the silica fine powder (A) has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively. B) has one or more peaks or shoulders in a range of 1 μm or more and less than 100 μm, and a frequency ratio of 0.04 μm or more and less than 1 μm in a particle of 0.04 to 2000 μm is 15% or less,
The toner has a weight average particle diameter D4 of 4 ≦ D4 ≦ 10 μm. The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
20 ≦ r (A) ≦ 32 nm, 7 ≦ r (B) ≦ 13 nm
The image forming method according to claim 1, wherein: The silica fine powder (B) is characterized in that a frequency ratio of 0.04 μm to less than 1 μm in a particle of 0.04 to 2000 μm is 8% or less in a volume average particle size distribution by a laser diffraction particle size distribution analyzer. The image forming method according to claim 1. 4. The image forming method according to claim 1, wherein both the silica fine powder (A) and the silica fine powder (B) are treated only with a silane coupling agent. 4. The image forming method according to claim 1, wherein both the silica fine powder (A) and the silica fine powder (B) are treated only with silicone oil. The image forming method according to any one of claims 1 to 3, wherein the silica fine powder (A) is treated only with silicone oil, and the silica fine powder (B) is treated only with a silane coupling agent. The silica fine powder (A) is produced by being subjected to a classification step and / or a crushing step after being treated with a silane coupling agent and / or a silicone oil. The image forming method described in 1. 8. The image forming method according to claim 1, wherein the toner has a weight average particle diameter D4 of 5 ≦ D4 ≦ 9 μm. 9. The silica fine powders (A) and (B) added in mass parts W (A) and W (B) with respect to 100 parts by mass of the toner particles satisfy the following formulas: The image forming method described.
0.05 ≦ W (A) ≦ 1.5
0.05 ≦ W (B) ≦ 1.8 The image according to any one of claims 1 to 8, wherein the added mass parts W (A) and W (B) of the silica fine powder (A) and (B) with respect to 100 parts by mass of the toner particles satisfy the following formula. Forming method.
0.1 ≦ W (A) ≦ 1.1
0.1 ≦ W (B) ≦ 1.5 11. The average circularity in a number-based equivalent circle diameter-circularity scattergram measured by the flow type particle image measuring apparatus for toner is 0.950 to 1.00. An image forming method according to claim 1. 11. The average circularity in a number-based equivalent circle diameter-circularity scattergram measured by the toner flow-type particle image measuring device is 0.960 to 1.00. An image forming method according to claim 1. 13. The image forming method according to claim 1, wherein the charging means for charging the latent image carrier is a charging roller. 14. The image forming method according to claim 1, wherein the latent image carrier is not in contact with a cleaning blade. Electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, information writing means for forming an electrostatic latent image on the charged electrostatic latent image carrier, and developer in the developing unit A developing means for visualizing the electrostatic latent image by supplying toner to the electrostatic latent image by the action of an electric field between the developer carrying body and the electrostatic latent image carrying body that are uniformly carried by the regulating member, and the visualized toner image In a toner used in an image forming method, which includes a transfer unit that transfers an image onto a transfer material via an intermediate transfer member, and a fixing unit that heat-contacts and presses the toner image on the transfer material.
The toner is a toner having at least toner particles and an external additive,
The external additive has at least two types of silica fine powders (A) and (B) treated with a silane coupling agent and / or silicone oil,
The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
18 ≦ r (A) ≦ 38 nm, 6 ≦ r (B) ≦ 14 nm
And
In the volume average particle size distribution by a laser diffraction type particle size distribution meter, the silica fine powder (A) has one or more peaks in the range of 0.04 μm or more and less than 1 μm and 1 μm or more and less than 100 μm, respectively. B) has one or more peaks or shoulders in a range of 1 μm or more and less than 100 μm, and a frequency ratio of 0.04 μm or more and less than 1 μm in a particle of 0.04 to 2000 μm is 15% or less,
The toner has a weight average particle diameter D4 of 4 ≦ D4 ≦ 10 μm. The primary average particle diameters r (A) and r (B) of the silica fine powders (A) and (B) are
20 ≦ r (A) ≦ 32 nm, 7 ≦ r (B) ≦ 13 nm
The toner according to claim 15, wherein: The silica fine powder (B) is characterized in that a frequency ratio of 0.04 μm to less than 1 μm in a particle of 0.04 to 2000 μm is 8% or less in a volume average particle size distribution by a laser diffraction particle size distribution analyzer. The toner according to claim 15 or 16. 18. The toner according to claim 15, wherein both the silica fine powder (A) and the silica fine powder (B) are treated only with a silane coupling agent. 18. The toner according to claim 15, wherein both the silica fine powder (A) and the silica fine powder (B) are treated only with silicone oil. The toner according to any one of claims 15 to 17, wherein the silica fine powder (A) is treated only with silicone oil, and the silica fine powder (B) is treated only with a silane coupling agent. The silica fine powder (A) is produced by being subjected to a classification step and / or a crushing step after being treated with a silane coupling agent and / or a silicone oil. The toner described in 1. The toner according to claim 15, wherein the toner has a weight average particle diameter D4 of 5 ≦ D4 ≦ 9 μm. 23. The mass ratio of W (A) and W (B) of the silica fine powder (A) and (B) added to 100 parts by mass of the toner particles satisfies the following formula. The toner described.
0.05 ≦ W (A) ≦ 1.5
0.05 ≦ W (B) ≦ 1.8 23. The mass ratio of W (A) and W (B) added to silica fine powder (A) and (B) with respect to 100 parts by mass of the toner particles satisfies the following formula: The toner described.
0.1 ≦ W (A) ≦ 1.1
0.1 ≦ W (B) ≦ 1.5 25. The average circularity in a circle-based equivalent diameter-circularity scattergram measured by the flow type particle image measuring device for toner is 0.950 to 1.00. Toner according to. 25. The average circularity in a number-based equivalent circle diameter-circularity scattergram measured by the flow type particle image measuring apparatus for toner is 0.960 to 1.00. Toner according to. 26. The toner according to claim 15, wherein the charging means for charging the latent image carrier is a charging roller. 28. The toner according to claim 15, wherein the latent image carrier is not in contact with a cleaning blade.

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