JP3937738B2 - Toner for developing electrostatic image, method for producing toner for developing electrostatic image, and image forming method - Google Patents

Description

【０１５５】
【化２】

【０１５６】
本発明の静電荷像現像用トナーを構成する離型剤の含有割合としては、通常１〜３０質量％とされ、好ましくは２〜２５質量％、更に好ましくは４〜２０質量％とされる。
【０１５７】
上記記載の離型剤は低分子量ポリプロピレン（数平均分子量＝１５００〜９０００）や低分子量ポリエチレン等を更に添加してもよい。
【０１５８】
本発明のトナー粒子は、結着樹脂相中に着色剤等が分離相を構成する海島構造を有する粒子が好ましく用いられるが、本発明においては、トナー粒子に占める島部の割合を表す尺度として、トナー粒子の海島構造中における島部の占有状態をボロノイ分割して得られるボロノイ多角形の面積により示す。
【０１５９】
また、本発明に記載の効果である、転写率の向上、ハーフトーンの均一性、微細ドットのチリが無くなるなどの効果が得られるので、本発明に係るトナー粒子は下記に定義されるようなボロノイ多角形（ボロノイ多面体ともいう）の面積の平均値が特定の範囲に入ることが好ましい。ここで、ボロノイ多角形について説明する。
【０１６０】
本発明に係るボロノイ多角形の面積とは、トナー粒子中における島部の占有状況を示す。ボロノイ多角形あるいはボロノイ多面体とは、例えば岩波理化学事典にも掲載されている様に、空間中、あるいは平面上に多数の点が分散しているときに隣り合った点の垂直２等分面、垂直２等分線を作ることにより空間全体を多面体に、または平面全体を多角形に分割させ、この様にして形成される多面体をボロノイ多面体、多角形をボロノイ多角形と呼び、この様な空間や平面の分割をボロノイ分割と呼ぶ。
【０１６１】
図２にボロノイ多角形（ボロノイ多面体）によって分割された本発明に係るトナー粒子の一例を示す。
【０１６２】
すなわち、本発明ではトナー粒子中に存在する島の重心に着目し、隣接し合う島の重心を結んで作られる垂直２等分線によって多角形を形成し、これらの多角形の面積を前記透過型電子顕微鏡より得られた撮影写真に基づき電子顕微鏡装置に設置された画像解析装置により算出する。
【０１６３】
ここで、ボロノイ多角形の面積が大きいものとは、隣接し合う島の重心間の距離が離れたものであることを示すものであり、すなわち、粒子中における島部の占有状態の疎な状態のものを示すものである。また、ボロノイ多角形の面積の小さいものとは、隣接し合う島の重心間の距離が短く近接しているものを示し、すなわち粒子中の島の占有状態が密な状態であることを示す。
【０１６４】
本発明では、トナー粒子中の島部のボロノイ多角形については１０００個のトナーについて測定を行い、ボロノイ多角形の面積の平均値を算出した。
【０１６５】
尚、ボロノイ多角形を数学的に一般定義すると、以下に示される式で定義されるものである。
【０１６６】
《ボロノイ多角形の面積》
２次元空間Ｒ２、または３次元空間Ｒ３におけるＮ個の独立した点Ｐ（ｉ）（１≦ｉ≦Ｎ）についてボロノイ多角形Ｖ（ｉ）の集合は、
Ｖ（ｉ）＝｛Ｘ｜｜Ｘ・Ｐ（ｉ）｜＜｜Ｘ・Ｐ（ｊ）｜
ｆｏｒ ａｌｌ ｉ ｔｏ ｊ｝
式中、Ｘ，Ｐは位置ベクトルで、｜ ｜はユークリッド空間における距離を示す。
【０１６７】
この様に定義されたＶ（ｉ）はＲ２ではボロノイ多角形、Ｒ３ではボロノイ多面体を形成すると仮定し、Ｖ（ｉ）とＶ（ｊ）とが隣合うときにボロノイ多角形の境界は、点Ｐ（ｉ）と点Ｐ（ｊ）を結ぶ線分の垂直２等分線の一部となるものと定義する。ユークリッド空間については、数理科学大辞典等に定義、記載されているとおりのものである。
【０１６８】
また、本発明のトナー粒子の重心、及びトナー粒子中の各島の重心は画像のモーメントによって得られるもので、透過型電子顕微鏡装置に設置された画像解析装置では自動的に算出される。ここで、トナー粒子の重心座標は、トナー粒子の任意の点における微小面積の有する輝度値とその任意の点の座標値との積を求める。そして、トナー粒子全体に存在する全座標について、その輝度と座標値の積を求め、その積の総和をトナー粒子の輝度（前述の様にして得られた各座標点における輝度値の総和）で除することで求められるものである。また、島の重心についても同様、島中の任意の座標点における輝度を求めることによって、島の重心も算出されるものである。この様に、本発明のトナー粒子の重心座標、及びトナー粒子中に存在する各島の重心座標とも各任意の点における輝度に基づき、すなわち画像の明暗から算出されるものである。
【０１６９】
本発明では、トナー粒子中の隣接し合う島の重心間の垂直２等分線により形成されるボロノイ多角形の面積の平均値が２０，０００〜１２０，０００ｎｍ²であり、かつその面積の平均値の変動係数が２５％以下のものである。本発明において、ボロノイ多角形の面積の変動係数は以下の式により算出される。
【０１７０】
ボロノイ多角形の面積の変動係数＝｛Ｓ４／Ｋ４｝×１００（％）
式中、Ｓ４はトナー粒子に存在する島部のボロノイ多角形の面積の標準偏差を示し、Ｋ４はボロノイ多角形の面積の平均値を示す。
【０１７１】
また、本発明に係るトナー粒子中の隣接し合う島のボロノイ多角形の面積の平均値については、より好ましくは４０，０００〜１００，０００ｎｍ²であり、かつその変動係数が２０％以下である。
【０１７２】
本発明に係るトナー粒子中の隣接し合う島の重心間の垂直２等分線により形成されるボロノイ多角形の面積の平均値は２０，０００〜１２０，０００ｎｍ２の範囲内にあるものであるが、この範囲から外れたものは、トナー粒子中における島部の占有状況が好ましくないものとなり、例えば粒子中に島として存在する着色剤がトナー粒子中へ効果的に添加されていないことを示すもので、本発明の効果を見出すことが困難となり好ましくない。
【０１７３】
本発明に係るトナー粒子中の隣接し合う島より形成されるボロノイ多角形の面積の平均値の変動係数とは、ボロノイ多角形の面積のバラツキを特定するもの、すなわちトナー粒子中における島部の占有状態のばらつきを特定するものであり、ボロノイ多角形の面積の平均値の変動係数が２５％以下の範囲であればよく、好ましくは２０％以下である。なお、変動係数が０％のとき、すなわち、ボロノイ多角形の面積の平均値にばらつきのない状態、換言すればトナー粒子中における島の占有状態に全くばらつきのない状態、どのトナー粒子も島の占有状態が同じものである必要性は全くない。
【０１７４】
また、本発明では、トナー粒子の重心から特定範囲内に存在する島により形成されるボロノイ多角形の面積が、その範囲外に存在する島により形成されるボロノイ多角形の面積よりも小さいものであることを特徴としているものである。すなわち、本発明ではトナー粒子の重心から半径１０００ｎｍの外に存在する島によって形成されるボロノイ多角形の面積の平均値が半径１０００ｎｍ以内に存在する島によって形成されるボロノイ多角形の面積の平均値よりも大きいものであり、このことはトナー粒子中においては、島の分散状態がトナー粒子の重心からある程度離れた箇所ではまばらになっていることを意味するものである。この条件を満足することで、本発明のトナーではトナー粒子中において島を適度に粒子中に分散させ本発明で達成させた効果が見出されるものである。
【０１７５】
また、本発明では、ボロノイ多角形の面積が１６０，０００ｎｍ²以上となる島がトナー粒子１個中に５〜３０個存在するものが好ましく、これは島が適度に分散していることを示すことを意味するものであり、この様に適度に島同士が距離を有していることで、トナー粒子中において島が偏在することがなく、着色剤がトナー粒子中に効果的に添加されていることを示す。
【０１７６】
また、本発明のトナーでは、トナー粒子が海島構造を有するものが好ましく、また、トナー粒子の外周に沿った領域において島の存在しない領域を有するものが好ましく用いられる。前記のような海島構造を有するトナー粒子について、図３で示すトナー粒子の概略断面図を用いて具体的に説明する。
【０１７７】
図３の概略断面図において、トナー粒子断面の外周に沿って長さａ、深さｂで示される領域が島を含まない領域である。
【０１７８】
本発明に係るトナー粒子においては、トナー粒子断面の外周に沿う領域において、深さ１００〜２００ｎｍ、長さ５００〜６０００ｎｍの島部を全く含まない領域を有するものが好ましく用いられる。
【０１７９】
この様にトナー粒子の外周に沿った特定領域内には島を存在させないことにより、特に島がトナー粒子からこぼれ落ちることを効果的に防止し、更にトナー粒子に添加された結晶性物質や着色剤を適度に粒子内に分散させると共に加圧定着時において結晶性物質を効果的に滲出させることが出来ると推測している。
【０１８０】
本発明に係るトナー粒子は、透過型電子顕微鏡観察の結果から、海島構造を有するものが好ましいが、トナー粒子中に添加される結晶性物質（例えば、上記記載の離型剤等）は結晶性物質の島が形成されており、着色剤は着色剤の島が形成されるもので、この様に添加剤の種類毎に複数種類の島が形成されているものが好ましい。これまで述べてきた特性は、同種、すなわち、結晶性物質の島間、あるいは着色剤の島間における特性であって異種の島間でのものではない。
【０１８１】
添加剤の異なる島、すなわち、結晶性物質の島と着色剤の島とは各々の輝度が異なるので、電子顕微鏡写真において容易に識別可能であり、前述した特性を算出する画像解析装置が誤って異種の島間の特性値を算出することはない様に設定されている。本発明のトナー粒子中における島について、結晶性物質の島は、フェレ径、島の形状係数、トナー粒子１個当たりに存在する島の個数によって特定されるものであり、また着色剤の島は、ボロノイ多角形の面積によって特定されるものである。
【０１８２】
本発明の静電荷像現像用トナーの製造方法について説明する。
本発明のトナーは、着色剤の不存在下において樹脂粒子を形成し、当該樹脂粒子の分散液に着色剤粒子の分散液を加え、当該樹脂粒子と着色剤粒子とを塩析、凝集、融着させることにより調製されるものである。
【０１８３】
このように、樹脂粒子の調製を着色剤の存在しない系で行うことにより、複合樹脂粒子を得るための重合反応が阻害されることない。このため、本発明のトナーによれば、優れた耐オフセット性が損なわれることはなく、トナーの蓄積による定着装置の汚染や画像汚れを発生させることはない。
【０１８４】
また、樹脂粒子を得るための重合反応が確実に行われる結果、得られるトナー粒子中に単量体やオリゴマーが残留するようなことはなく、当該トナーを使用する画像形成方法の熱定着工程において、異臭を発生させることはない。
【０１８５】
さらに、得られるトナー粒子の表面特性は均質であり、帯電量分布もシャープとなるため、鮮鋭性に優れた画像を長期にわたり形成することができる。
【０１８６】
本発明のトナーを構成する樹脂粒子は、樹脂からなる核粒子の表面を覆うように、当該核粒子を形成する樹脂とは分子量および／または組成の異なる樹脂からなる１または２以上の被覆層が形成されている多層構造の樹脂粒子が好ましい。
【０１８７】
すなわち樹脂粒子の分子量分布は単分散ではなく、また、樹脂粒子は、通常、その中心部（核）〜外層（殻）にかけて分子量勾配を有することが好ましい。
【０１８８】
本発明において、樹脂粒子を得るために「多段重合法」を用いることが、分子量分布制御の観点から、すなわち定着強度、耐オフセット性を確保する観点から好ましい。本発明において、樹脂粒子を得るための「多段重合法」とは、単量体（ｎ）を重合処理（第ｎ段）して得られた樹脂粒子（ｎ）の存在下に、単量体（ｎ＋１）を重合処理（第ｎ＋１段）して、当該樹脂粒子（ｎ）の表面に、単量体（ｎ＋１）の重合体（樹脂粒子（ｎ）の構成樹脂とは分散および／または組成の異なる樹脂）からなる被覆層（ｎ＋１）を形成する方法を示す。
【０１８９】
ここに、樹脂粒子（ｎ）が核粒子である場合（ｎ＝１）には、「二段重合法」となり、樹脂粒子（ｎ）が複合樹脂粒子である場合（ｎ≧２）には、三段以上の多段重合法となる。
【０１９０】
多段重合法によって得られる複合樹脂粒子中には、組成および／または分子量が異なる複数の樹脂が存在することになる。従って、当該複合樹脂粒子と着色剤粒子とを塩析、凝集、融着させることにより得られるトナーは、トナー粒子間において、組成・分子量・表面特性のバラツキがきわめて小さい。
【０１９１】
このようなトナー粒子間における組成・分子量・表面特性が均質であるトナーによれば、接触加熱方式による定着工程を含む画像形成方法において、画像支持体に対する良好な接着性（高い定着強度）を維持しながら、耐オフセット性および巻き付き防止特性の向上を図ることができ、適度の光沢を有する画像を得ることができる。
【０１９２】
本発明の静電荷像現像用トナーの製造方法の一例を具体的に示すと、
（１）樹脂粒子を得るための重合工程
（２）樹脂粒子と着色剤粒子とを塩析、凝集、融着させてトナー粒子を得る塩析、凝集、融着する工程（II）、
（３）トナー粒子の分散系からトナー粒子を濾別し、トナー粒子から界面活性剤などを除去する濾過、洗浄工程、
（４）洗浄処理されたトナー粒子を乾燥する乾燥工程、
（５）乾燥処理されたトナー粒子に外添剤を添加する工程から構成される。
【０１９３】
以下、各工程について説明する。
離型剤を樹脂粒子（核粒子）に含有させる方法としては、離型剤を単量体に溶解させ、得られる単量体溶液を水系媒体中に油滴分散させ、この系を重合処理することにより、ラテックス粒子として得る方法を採用することができる。
【０１９４】
《塩析、凝集、融着する工程（II）》
この塩析、凝集、融着する工程（II）は、重合工程（Ｉ）によって得られた樹脂粒子と、着色剤粒子とを塩析、凝集、融着させる（塩析と融着とを同時に起こさせる）ことによって、非球形のトナー粒子を得る工程である。
【０１９５】
この塩析、凝集、融着する工程（II）においては、複合樹脂粒子および着色剤粒子とともに、エステルワックスなどの離型剤、荷電制御剤などの内添剤粒子（数平均一次粒子径が１０〜１０００ｎｍ程度の微粒子）を加え、塩析、凝集、融着させてもよい。
【０１９６】
着色剤粒子は、表面改質されていてもよい。ここに、表面改質剤としては、従来公知のものを使用することができる。
【０１９７】
着色剤粒子は、水性媒体中に分散された状態で塩析、凝集、融着処理に供される。着色剤粒子が分散される水性媒体は、臨界ミセル濃度（ＣＭＣ）以上の濃度で界面活性剤が溶解されている水溶液を挙げることができる。
【０１９８】
ここに界面活性剤としては、多段重合工程（Ｉ）で使用した界面活性剤と同一のものを使用することができる。
【０１９９】
着色剤粒子の分散処理に使用する分散機は特に限定されないが、好ましくは、高速回転するローターを備えた攪拌装置「クレアミックス（ＣＬＥＡＲＭＩＸ）」（エム・テクニック（株）製）、超音波分散機、機械的ホモジナイザー、マントンゴーリン、圧力式ホモジナイザー等の加圧分散機、ゲッツマンミル、ダイヤモンドファインミル等の媒体型分散機が挙げられる。
【０２００】
樹脂粒子と着色剤粒子とを塩析、凝集、融着させるためには、樹脂粒子および着色剤粒子が分散している分散液中に、臨界凝集濃度以上の凝集剤を添加するとともに、この分散液を、樹脂粒子のガラス転移温度（Ｔｇ）以上に加熱することが好ましい。
【０２０１】
更に好ましくは、凝集剤により複合樹脂粒子が所望の粒径に達した段階で凝集停止剤が用いられる。その凝集停止剤としては、１価の金属塩、中でも塩化ナトリウムが好ましく用いられる。
【０２０２】
塩析、凝集、融着させるために好適な温度範囲としては、（Ｔｇ＋１０）〜（Ｔｇ＋５０℃）とされ、特に好ましくは（Ｔｇ＋１５）〜（Ｔｇ＋４０℃）とされる。また、融着を効果的に行なわせるために、水に無限溶解する有機溶媒を添加してもよい。
【０２０３】
ここに、塩析、凝集、融着の際に使用する「凝集剤」としては、前述のようなアルカリ金属塩およびアルカリ土類金属塩を挙げることができる。
【０２０４】
本発明に係る塩析、凝集について説明する。
本発明において、「塩析、凝集、融着」するとは、塩析（粒子の凝集）と融着（粒子間の界面消失）とが同時に起こること、または、塩析と融着とを同時に起こさせる行為をいう。
【０２０５】
塩析と融着とを同時に行わせるためには、複合樹脂粒子を構成する樹脂のガラス転移温度（Ｔｇ）以上の温度条件下において粒子（複合樹脂粒子、着色剤粒子）を凝集させることが好ましい。
【０２０６】
本発明の静電荷像現像用トナーは、着色剤の不存在下において樹脂粒子を形成し、当該複合樹脂粒子の分散液に着色剤粒子の分散液を加え、あるいは必要に応じ離型剤分散液を加え当該樹脂粒子と着色剤粒子、離型剤、荷電制御剤とを塩析、凝集、融着させることにより調製されることが好ましい。
【０２０７】
このように、樹脂粒子の調製を着色剤の存在しない系で行うことにより、複合樹脂粒子を得るための重合反応が阻害されることない。このため、本発明のトナーによれば、優れた耐オフセット性が損なわれることはなく、トナーの蓄積による定着装置の汚染や画像汚れを発生させることはない。
【０２０８】
また、複合樹脂粒子を得るための重合反応が確実に行われる結果、得られるトナー粒子中に単量体やオリゴマーが残留するようなことはなく、当該トナーを使用する画像形成方法の熱定着工程において、異臭を発生させることはない。
【０２０９】
さらに、得られるトナー粒子の表面特性は均質であり、帯電量分布もシャープとなるため、鮮鋭性に優れた画像を長期にわたり形成することができる。このようなトナー粒子間における組成・分子量・表面特性が均質であるトナーによれば、接触加熱方式による定着工程を含む画像形成方法において、画像支持体に対する良好な接着性（高い定着強度）を維持しながら、耐オフセット性の向上を図ることができ、適度の光沢を有する画像を得ることができる。
【０２１０】
上記記載の樹脂粒子形成に用いられる樹脂としては、例えば、熱可塑性結着樹脂などが挙げられ、具体的には、スチレン、パラクロロスチレン、α−メチルスチレン等のスチレン類の単独重合体または共重合体（スチレン系樹脂）；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−プロピル、アクリル酸ｎ−ブチル、アクリル酸ラウリル、アクリル酸２−エチルヘキシル、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、メタクリル酸ラウリル、メタクリル酸２−エチルヘキシル等のビニル基を有するエステル類の単独重合体または共重合体（ビニル系樹脂）；アクリロニトリル、メタクリロニトリル等のビニルニトリル類の単独重合体または共重合体（ビニル系樹脂）；ビニルメチルエーテル、ビニルイソブチルエーテル等のビニルエーテル類の単独重合体または共重合体（ビニル系樹脂）；ビニルメチルケトン、ビニルエチルケトン、ビニルイソプロペニルケトン等のビニルケトン類の単独重合体または共重合体（ビニル系樹脂）；エチレン、プロピレン、ブタジエン、イソプレン等のオレフィン類の単独重合体または共重合体（オレフィン系樹脂）；エポキシ樹脂、ポリエステル樹脂、ポリウレタン樹脂、ポリアミド樹脂、セルロース樹脂、ポリエーテル樹脂等の非ビニル縮合系樹脂、及びこれらの非ビニル縮合系樹脂とビニル系モノマーとのグラフト重合体などが挙げられる。これらの樹脂は、１種単独で使用してもよいし、２種以上を併用してもよい。
【０２１１】
これらの樹脂の中でもビニル系樹脂が特に好ましい。ビニル系樹脂の場合、イオン性界面活性剤などを用いて乳化重合やシード重合により樹脂粒子分散液を容易に調製することができる点で有利である。前記ビニル系モノマーとしては、例えば、アクリル酸、メタクリル酸、マレイン酸、ケイ皮酸、フマル酸、ビニルスルフォン酸、エチレンイミン、ビニルピリジン、ビニルアミンなどのビニル系高分子酸やビニル系高分子塩基の原料となるモノマーが挙げられる。本発明においては、前記樹脂粒子が、前記ビニル系モノマーをモノマー成分として含有するのが好ましい。本発明においては、これらのビニル系モノマーの中でも、ビニル系樹脂の形成反応の容易性等の点でビニル系高分子酸がより好ましく、具体的にはアクリル酸、メタクリル酸、マレイン酸、ケイ皮酸、フマル酸などのカルボキシル基を解離基として有する解離性ビニル系モノマーが、重合度やガラス転移点の制御の点で特に好ましい。
【０２１２】
尚、前記解離性ビニル系モノマーにおける解離基の濃度は、例えば、高分子ラテックスの化学（高分子刊行会）に記載されているような、トナー粒子等の粒子を表面から溶解して定量する方法などにより決定することができる。なお、前記方法等により、粒子の表面から内部にかけての樹脂の分子量やガラス転移点を決定することもできる。
【０２１３】
前記樹脂粒子の個数平均粒径としては、通常、大きくとも１μｍ（１μｍ以下）であり、０．０１〜１μｍであるのが好ましい。前記個数平均粒径が１μｍを越えると、最終的に得られる静電荷像現像用トナーの粒径分布が広くなったり、遊離粒子の発生が生じ、性能や信頼性の低下を招き易い。一方、前記個数平均粒径が前記範囲内にあると前記欠点がない上、トナー間の偏在が減少し、トナー中の分散が良好となり、性能や信頼性のバラツキが小さくなる点で有利である。なお、前記個数平均粒径は、例えばコールターカウンターなどを用いて測定することができる。
【０２１４】
前記着色剤分散液は、少なくとも着色剤を分散させてなる。前記着色剤としては、例えば、カーボンブラック、クロムイエロー、ハンザイエロー、ベンジジンイエロー、スレンイエロー、キノリンイエロー、パーマネントオレンジＧＴＲ、ピラゾロンオレンジ、バルカンオレンジ、ウオッチヤングレッド、パーマネントレッド、ブリリアントカーミン３Ｂ、ブリリアントカーミン６Ｂ、デュポンオイルレッド、ピラゾロンレッド、リソールレッド、ローダミンＢレーキ、レーキレッドＣ、ローズベンガル、アニリンブルー、ウルトラマリンブルー、カルコオイルブルー、メチレンブルークロライド、フタロシアニンブルー、フタロシアニングリーン、マラカイトグリーンオキサレートなどの種々の顔料；アクリジン系、キサンテン系、アゾ系、ベンゾキノン系、アジン系、アントラキノン系、ジオキサジン系、チアジン系、アゾメチン系、インジコ系、チオインジコ系、フタロシアニン系、アニリンブラック系、ポリメチン系、トリフェニルメタン系、ジフェニルメタン系、チアジン系、チアゾール系、キサンテン系などの各種染料；などが挙げられる。これらの着色剤は、１種単独で使用してもよいし、２種以上を併用してもよい。
【０２１５】
前記着色剤の個数平均粒径としては、通常大きくとも１μｍ（即ち１μｍ以下）であるが、大きくとも０．５μｍ（即ち０．５μｍ以下）が好ましく、０．０１〜０．５μｍが特に好ましい。前記個数平均粒径が１μｍを越えると、最終的に得られる静電荷像現像用トナーの粒径分布が広くなったり、遊離粒子の発生が生じ、性能や信頼性の低下を招き易い。一方、前記個数平均粒径が前記範囲内にあると前記欠点がない上、トナー間の偏在が減少し、トナー中の分散が良好となり、性能や信頼性のバラツキが小さくなる点で有利である。更に、前記個数平均粒径が０．５μｍ以下であると、得られるトナー粒子が、発色性、色再現性、ＯＨＰ透過性等に優れる点で有利である。なお、前記個数平均粒径は、例えばマイクロトラックなどを用いて測定することができる。
【０２１６】
本発明に用いられる帯電制御剤としては、例えば、４級アンモニウム塩化合物、ニグロシン系化合物、アルミ、鉄、クロムなどの錯体からなる染料、トリフェニルメタン系顔料などが挙げられる。なお、本発明における帯電制御剤としては、凝集時や融合時の安定性に影響するイオン強度の制御と廃水汚染減少の点で、水に溶解しにくい素材のものが好ましい。
【０２１７】
本発明に用いられる現像剤について説明する。
本発明のトナーは、一成分現像剤でも二成分現像剤として用いてもよい。
【０２１８】
一成分現像剤として用いる場合は、非磁性一成分現像剤、あるいはトナー中に０．１〜０．５μｍ程度の磁性粒子を含有させ磁性一成分現像剤としたものがあげられ、いずれも使用することができる。
【０２１９】
また、キャリアと混合して二成分現像剤として用いることができる。この場合は、キャリアの磁性粒子として、鉄、フェライト、マグネタイト等の金属、それらの金属とアルミニウム、鉛等の金属との合金等の従来から公知の材料を用いることが出来る。特にフェライト粒子が好ましい。上記磁性粒子は、その個数平均粒径としては１５〜１００μｍ、より好ましくは２５〜８０μｍのものがよい。
【０２２０】
キャリアの個数平均粒径の測定は、代表的には湿式分散機を備えたレーザ回折式粒度分布測定装置「ヘロス（ＨＥＬＯＳ）」（シンパティック（ＳＹＭＰＡＴＥＣ）社製）により測定することができる。
【０２２１】
本発明に係る画像形成方法について説明する。
本発明に係る画像形成方法とは、感光体上に帯電、像露光を行って形成した静電潜像を、静電潜像現像用トナーを含有する現像剤にて現像し形成したトナー画像を、接触転写方式を用いて転写材に転写し、その後分離、定着及びクリーニングを行う各工程を繰り返すことにより、多数枚の画像を形成する画像形成方法を云う。
【０２２２】
図４は転写ロールを用いた画像形成装置の一例を示す概略構成図である。
図４に於いて感光体１０は矢印方向に回転する有機感光体であり、１１は前記感光体に一様な帯電を付与する帯電器であり、帯電器はコロナ放電器、ローラ帯電器、磁気ブラシ帯電器であってもよい。１２はアナログ像露光または半導体レーザー、発光ダイオード等を用いたデジタル像露光光であり、該像露光光により感光体上に静電潜像が形成される。この静電潜像は個数平均粒径２〜１０μｍの微粒子トナーを含有する現像剤を収納する現像器１３により接触または非接触で現像されて、前記感光体上にトナー画像が形成される。
【０２２３】
前記トナー画像はタイミングを合わせて搬送された転写材Ｐ上に転写ロール１５により直流バイアス印加下、感光体への押圧力２．５〜１００ｋＰａ、好ましくは１０〜８０ｋＰａで転写される。
【０２２４】
前記転写ロール１５へバイアス印加する直流バイアスの電源１６は、好ましくは定電流電源または定電圧電源であり、前記定電流電源の場合は５〜１５μＡであり、定電圧電源の場合は絶対値で４００〜１５００Ｖである。
【０２２５】
前記転写ロール１５により画像が転写された転写材Ｐは感光体１０から分離極１４により分離され図示しない定着器へと搬送されて加熱定着される。
【０２２６】
転写後の感光体表面は、クリーニングブレード１７によりクリーニングされ、その後除電ランプ（ＰＣＬ）１８で除電されて次の画像形成に備えられる。なお１９は給紙ローラであり、２０は定着器である。
【０２２７】
（中間転写体）
感光体から転写材へトナー画像の転写は、中間転写体を用いる方式でも行うことが出来る。即ち、各々４色の現像剤ごとに画像形成部（画像形成ユニット）を設け、各画像形成部に於いて各感光体に各色ごとの可視画像を形成し、これら可視画像を中間転写体に順次転写し、一括して転写材（通常は普通紙であるが、転写可能なものであれば特に限定はない）に転写後、定着してカラー画像を得る方式にも好ましく用いることが出来る。
【０２２８】
複数色の画像を画像形成部にて形成し、これを同一中間転写体に順次重ねて転写するようにした画像形成方法を図に基づいて説明する。
【０２２９】
図５は中間転写体（転写ベルト）を用いた画像形成装置の一例を示す概略構成図である。
【０２３０】
図５に於いて、カラー画像を得るため画像形成装置は、複数個の画像形成ユニットを備え、各画像形成ユニットにてそれぞれ色の異なる可視画像（トナー画像）を形成し、該トナー画像を同一中間転写体に順次重ねて転写するような画像形成方法である。
【０２３１】
ここでは、第１、第２、第３及び第４の画像形成ユニットＰａ、Ｐｂ、Ｐｃ及びＰｄが並設されており、該画像形成部はそれぞれ静電潜像形成体である感光体１ａ、１ｂ、１ｃ及び１ｄを具備している。
【０２３２】
感光体１ａ、１ｂ、１ｃ及び１ｄはその外周側に潜像形成部２ａ、２ｂ、２ｃ及び２ｄ、現像部３ａ、３ｂ、３ｃ及び３ｄ、転写放電部４ａ、４ｂ、４ｃ及び４ｄ、クリーニング部材及びゴムブレードを有するクリーニング器５ａ、５ｂ、５ｃ及び５ｄ、帯電器６ａ、６ｂ、６ｃ及び６ｄが配置されている。
【０２３３】
このような構成にて、先ず、第１画像形成ユニットＰａの感光体１ａ上に潜像形成部２ａによって原稿画像における、例えばイエロー成分色の潜像が形成される。該潜像は現像部３ａのイエロートナーを含有する現像剤で可視画像とされ、転写放電部４ａにて、転写ベルト２１に転写される。
【０２３４】
一方、上記のようにイエロートナー画像が転写ベルト２１に転写されている間に、第２画像形成ユニットＰｂではマゼンタ成分色の潜像が感光体１ｂ上に形成され、続いて現像部３ｂでマゼンタトナーを含有する現像剤で可視画像とされる。この可視画像（マゼンタトナー画像）は、上記の第１画像形成ユニットＰａでの転写が終了した転写ベルトが転写放電部４ｂに搬入されたときに、該転写ベルト２１の所定位置に重ねて転写される。
【０２３５】
以下、上記と同様な方法により第３、第４の画像形成ユニットＰｃ、Ｐｄによってシアン成分色、ブラック成分色の画像形成が行われ、上記同一の転写ベルト上に、シアントナー画像、ブラックトナー画像が重ねて転写される。このような画像形成プロセスが終了した時点で、転写ベルト２１上に多色重ね合せ画像が得られる。一方、転写が終了した各感光体１ａ、１ｂ、１ｃ及び１ｄはクリーニング器５ａ、５ｂ、５ｃ及び５ｄにより残留トナーが除去され、引き続き行われる次の潜像形成のために供せられる。
【０２３６】
尚、前記画像形成装置では、転写ベルト２１が用いられており、図５に於いて、転写ベルト２１は右側から左側へと搬送され、その搬送過程で、各画像形成ユニットＰａ、Ｐｂ、Ｐｃ及びＰｄにおける各転写放電部４ａ、４ｂ、４ｃ及び４ｄを通過し、各色転写画像が転写される。
【０２３７】
転写ベルト２１が第４画像形成ユニットＰｄを通過すると、ＡＣ電圧が分離除電放電器２２ｄに加えられ、転写ベルト２１は除電され、転写材Ｐにトナー像が一括転写される。その後転写材Ｐは定着装置２３に入り、定着され、排出口２５から排出される。
【０２３８】
尚、図中、２２ａ、２２ｂ、２２ｃ及び２２ｄは分離除電放電器である。
又、トナー像の転写を終えた転写ベルト２１は、ブラシ状クリーニング部材とゴムブレードを併用したクリーニング器２４により、転写残トナーがクリーニングされて、次の画像形成に備えられる。
【０２３９】
尚、前記した如く、搬送ベルトの如き長尺の転写ベルト２１を用いて、その上に多色重ね合わせ像を作り、それを転写材に一括転写する構成にしても、その画像形成ユニットにそれぞれ独立した転写ベルトを具備させ、それから転写材へ、順次各転写ベルトから転写する構成にしてもよい。
【０２４０】
尚、前記転写ベルトとしては、例えばポリイミド、ポリエーテル、ポリアミド或いはテトラフルオロエチレン・パーフルオロビニルエーテル共重合体等の表面抵抗が１０¹⁴Ω以上で、厚さ２０μｍ程度の高抵抗フィルムの上に、フッ素系またはシリコン系樹脂に導電剤を添加して表面抵抗を１０⁵〜１０⁸Ωとした５〜１５μｍ厚の離型層を設けて成るエンドレスフィルムが用いられる。
【０２４１】
また、本発明に使用される好適な定着方法としては、いわゆる接触加熱方式を図６（ａ）、（ｂ）を用いて説明する。
【０２４２】
図６（ａ）、（ｂ）は、各々、本発明に用いられる定着器の一態様を示す概略断面図である。
【０２４３】
本発明においては、特に、接触加熱方式として、熱圧定着方式、さらには熱ロール定着方式および固定配置された加熱体を内包した回動する加圧部材により定着する圧接加熱定着方式をあげることができる。
【０２４４】
熱ロール定着方式では、多くの場合表面にテトラフルオロエチレンやポリテトラフルオロエチレン−パーフルオロアルコキシビニルエーテル共重合体類等を被覆した鉄やアルミニウム等で構成される金属シリンダー内部に熱源を有する上ローラーとシリコーンゴム等で形成された下ローラーとから形成されている。熱源としては、線状のヒーターを有し、上ローラーの表面温度を１２０〜２００℃程度に加熱するものが代表例である。定着部に於いては上ローラーと下ローラー間に圧力を加え、下ローラーを変形させ、いわゆるニップを形成する。ニップ幅としては１〜１０ｍｍ、好ましくは１．５〜７ｍｍである。定着線速は４０ｍｍ／ｓｅｃ〜６００ｍｍ／ｓｅｃが好ましい。
【０２４５】
定着クリーニングの機構を付与して使用してもよい。この方式としてはシリコーンオイルを定着の上ローラーあるいはフィルムに供給する方式やシリコーンオイルを含浸したパッド、ローラー、ウェッブ等でクリーニングする方法が使用できる。
【０２４６】
次に、本発明で用いられる固定配置された加熱体を内包した回動する加圧部材により定着する方式について説明する。
【０２４７】
この定着方式は、固定配置された加熱体と、該加熱体に対向圧接し、且つフィルムを介して転写材を加熱体に密着させる加圧部材とにより圧接加熱定着する方式である。
【０２４８】
この圧接加熱定着器は、加熱体が従来の加熱ローラーに比べて熱容量が小さく、転写材の通過方向と直角方向にライン状の加熱部を有するものであり、通常加熱部の最高温度は１００〜３００℃である。
【０２４９】
なお、圧接加熱定着とは、通常よく用いられるごとく加熱部材と加圧部材の間を、未定着トナーをした転写材を通す方式等、加熱源に未定着トナー像を押し当てて定着する方法である。こうすることにより加熱が迅速に行われるため、定着の高速化が可能となるが、温度制御が難しく、加熱源表面部分等の未定着トナーを直接圧接される部分に、トナーが付着残留したいわゆるトナーオフセットが起こりやすく、また転写材が定着器に巻き付きを起こす等の故障も起こしやすいという問題点もある。
【０２５０】
この定着方式では、装置に固定支持された低熱容量のライン状加熱体は、厚さにして０．２〜５．０ｍｍ、さらに好ましくは０．５〜３．５ｍｍで幅１０〜１５ｍｍ、長手長２４０〜４００ｍｍのアルミナ基板に抵抗材料を１．０〜２．５ｍｍに塗布したもので両端より通電される。
【０２５１】
通電はＤＣ１００Ｖの周期１５〜２５ｍｓｅｃのパルス波形で、温度センサーにより制御された温度・エネルギー放出量に応じたパルス幅に変化させてあたえる。低熱容量ライン状加熱体において、温度センサーで検出された温度Ｔ１の場合、抵抗材料に対向するフィルムの表面温度Ｔ２はＴ１よりも低い温度となる。ここでＴ１は１２０〜２２０℃が好ましく、Ｔ２の温度はＴ１の温度と比較して０．５〜１０℃低いことが好ましい。また、フィルムがトナー表面より剥離する部分におけるフィルム材表面温度Ｔ３はＴ２とほぼ同等である。フィルムは、この様にエネルギー制御・温度制御された加熱体に当接して図６（ａ）の中央矢印方向に移動する。これら定着用フィルムとして用いられるものは、厚みが１０〜３５μｍの耐熱フィルム、例えばポリエステル、ポリパーフルオロアルコキシビニルエーテル、ポリイミド、ポリエーテルイミドに、多くの場合はテフロン等のフッ素樹脂に導電材を添加し離型剤層を、５〜１５μｍ被覆させたエンドレスフィルムである。
【０２５２】
フィルムの駆動には、駆動ローラーと従動ローラーにより駆動力とテンションをかけられて矢印方向へシワ・ヨレがなく搬送される。定着器としての線速は４０〜６００ｍｍ／ｓｅｃが好ましい。
【０２５３】
加圧ローラーはシリコーンゴム等の離型性の高いゴム弾性層を有し、フィルム材を介して加熱体に圧着され、圧接回転する。
【０２５４】
また、上記にはエンドレスフィルムを用いた例を説明したが、図６（ｂ）の様にフィルムシートの送り出し軸と巻き取り軸を使用し、有端のフィルム材を使用してもよい。さらには内部に駆動ローラー等を有しない単なる円筒状のものでもよい。
【０２５５】
上記定着器にはクリーニング機構を付与して使用してもよい。クリーニング方式としては、各種シリコーンオイルを定着用フィルムに供給する方式や各種シリコーンオイルを含浸させたパッド、ローラー、ウェッブ等でクリーニングする方式が用いられる。
【０２５６】
なお、シリコーンオイルとしては、ポリジメチルシロキサン、ポリメチルフェニルシロキサン、ポリジフェニルシロキサン等を使用することが出来る。さらに、フッ素を含有するシロキサンも好適に使用することが出来る。
【０２５７】
次に図６にこの定着器の構成断面図の例を示す。
図６（ａ）において、８４は装置に固定支持された低熱容量ライン状加熱体であって、一例として高さが１．０ｍｍ、幅が１０ｍｍ、長手長が２４０ｍｍのアルミナ基板８５に抵抗材料８６を幅１．０ｍｍに塗工したものであり、長手方向両端部より通電される。
【０２５８】
通電は例えばＤＣ１００Ｖで通常は周期２０ｍｓｅｃのパルス状波形でなされ、検温素子８７からの信号によりコントロールされ所定温度に保たれる。このためエネルギー放出量に応じてパルス幅を変化させるが、その範囲は例えば０．５〜５ｍｓｅｃである。
【０２５９】
このように制御された加熱体８４に移動するフィルム８８を介して未定着トナー像９３を担持した転写材９４を当接させてトナーを熱定着する。
【０２６０】
ここで用いられるフィルム８８は、駆動ローラー８９と従動ローラー９０によりテンションをかけられた状態でシワの発生なく移動する。９５はシリコーンゴム等で形成されたゴム弾性層を有する加圧ローラーであり、総圧０．４〜２．０Ｎでフィルムを介して加熱体を加圧している。転写材９４上の未定着トナー像９３は、入口ガイド９６により定着部に導かれ、加熱により定着像を得る。
【０２６１】
以上はエンドレスベルトで説明したが、図６（ｂ）のごとく、フィルムシート繰り出し軸９１および巻き取り軸９２を使用し、定着用のフィルムは有端のものでもよい。
【０２６２】
【実施例】
以下、実施例にて本発明を詳細に説明するが本発明はこれらに限定されない。
【０２６３】
実施例１
《ラテックスの調製》
（ラテックス１ＨＭＬの調製）
（１）核粒子の調製（第１段重合）：（ラテックス１Ｈの調製）
攪拌装置、温度センサー、冷却管、窒素導入装置を取り付けた５０００ｍｌのセパラブルフラスコに、下記のアニオン系界面活性剤（１０１）
（１０１） Ｃ₁₀Ｈ₂₁（ＯＣＨ₂ＣＨ₂）₂ＯＳＯ₃Ｎａ
７．０８ｇをイオン交換水３０１０ｇに溶解させた界面活性剤溶液（水系媒体）を仕込み、窒素気流下２３０ｒｐｍの攪拌速度で攪拌しながら、内温を８０℃に昇温させた。
【０２６４】
この界面活性剤溶液に、重合開始剤（過硫酸カリウム：ＫＰＳ）９．２ｇをイオン交換水２００ｇに溶解させた開始剤溶液を添加し、温度を７５℃とした後、スチレン７０．１ｇ、ｎ−ブチルアクリレート１９．９ｇ、メタクリル酸１０．９ｇからなる単量体混合液を１時間かけて滴下し、この系を７５℃にて２時間にわたり加熱、攪拌することにより重合（第１段重合）を行い、ラテックス（高分子量樹脂からなる樹脂粒子の分散液）を調製した。これを「ラテックス（１Ｈ）」とする。
【０２６５】
（２）中間層の形成（第２段重合）：（ラテックス１ＨＭの調製）
攪拌装置を取り付けたフラスコ内において、スチレン１０５．６ｇ、ｎ−ブチルアクリレート３０．０ｇ、メタクリル酸６．２ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル５．６ｇからなる単量体混合液に、上記例示化合物２０）で表されるエステル化合物（脂肪酸ユニットの炭素数２０）９８．０ｇを添加し、８５℃に加温し溶解させて単量体溶液を調製した。
【０２６６】
一方、アニオン系界面活性剤（１０１）１．６ｇをイオン交換水２７００ｍｌに溶解させた界面活性剤溶液を９５℃に加熱し、この界面活性剤溶液に、核粒子の分散液である前記ラテックス（１Ｈ）を固形分換算で２８ｇ添加した後、循環経路を有する機械式分散機「クレアミックス（ＣＬＥＡＲＭＩＸ）」（エム・テクニック（株）製）により、前記例示化合物１９）の単量体溶液を６時間混合分散させ、分散粒子径（２８４ｎｍ）を有する乳化粒子（油滴）を含む分散液（乳化液）を調製した。
【０２６７】
次いで、この分散液（乳化液）に、重合開始剤（ＫＰＳ）５．１ｇをイオン交換水２４０ｍｌに溶解させた開始剤溶液と、イオン交換水７５０ｍｌとを添加し、この系を８０〜９８℃にて１〜１２時間にわたり加熱攪拌することにより重合（第２段重合）を行い、ラテックス（高分子量樹脂からなる樹脂粒子の表面が中間分子量樹脂により被覆された構造の複合樹脂粒子の分散液）を得た。これを「ラテックス（１ＨＭ）」とする。
【０２６８】
前記ラテックス（１ＨＭ）を乾燥し、走査型電子顕微鏡で観察したところ、ラテックスに取り込まれなかった例示化合物１９）を主成分とする粒子（４００〜１０００ｎｍ）が観察された。
【０２６９】
（３）外層の形成（第３段重合）：（ラテックス１ＨＭＬの調製）
上記のようにして得られたラテックス（１ＨＭ）に、重合開始剤（ＫＰＳ）７．４ｇをイオン交換水２００ｍｌに溶解させた開始剤溶液を添加し、８０℃の温度条件下に、スチレン３００ｇ、ｎ−ブチルアクリレート９５ｇ、メタクリル酸１５．３ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル１０．４ｇからなる単量体混合液を１時間かけて滴下した。滴下終了後、２時間にわたり加熱攪拌することにより重合（第３段重合）を行った後、２８℃まで冷却しラテックス（高分子量樹脂からなる中心部と、中間分子量樹脂からなる中間層と、低分子量樹脂からなる外層とを有し、前記中間層に例示化合物１９）が含有されている複合樹脂粒子の分散液）を得た。このラテックスを「ラテックス（１ＨＭＬ）」とする。
【０２７０】
このラテックス（１ＨＭＬ）を構成する複合樹脂粒子は、１３８，０００、８０，０００および１３，０００にピーク分子量を有するものであり、また、この複合樹脂粒子の個数平均粒径は１２２ｎｍであった。
【０２７１】
（ラテックス２ＨＭＬの調製）
ラテックス（１ＨＭＬ）の製造において、例示化合物２０）の代わりに例示化合物２１）（脂肪酸ユニットの炭素数１８）とした以外は同様にして、ラテックス２ＨＭＬを得た。
【０２７２】
このラテックス（２ＨＭＬ）を構成する複合樹脂粒子は、１４６，０００、９０，０００および１３，０００にピーク分子量を有するものであり、また、この複合樹脂粒子の個数平均粒径は１２６ｎｍであった。
【０２７３】
（ラテックス３ＨＭＬの調製）
ラテックス（３ＨＭＬ）の製造において、例示化合物２０）の代わりに例示化合物１８）（脂肪酸ユニットの炭素数２８）とした以外は同様にして、ラテックス３ＨＭＬを得た。
【０２７４】
このラテックス（３ＨＭＬ）を構成する複合樹脂粒子は、１１７，０００、９０，０００および１２，０００にピーク分子量を有するものであり、また、この複合樹脂粒子の個数平均粒径は１１８ｎｍであった。
【０２７５】
《着色粒子１の製造》
アニオン系界面活性剤（１０１）５９．０ｇをイオン交換水１６００ｍｌに攪拌溶解した。この溶液を攪拌しながら、４２０．０ｇのＣ．Ｉ．ピグメント・レッド１２２を徐々に添加し、次いで、「クレアミックス」（エム・テクニック（株）製）を用いて分散処理することにより、着色剤粒子の分散液（以下、「着色剤分散液１」という）を調製した。この着色剤分散液における着色剤粒子の粒子径を、電気泳動光散乱光度計「ＥＬＳ−８００」（大塚電子社製）を用いて測定したところ、重量平均粒子径で８９ｎｍであった。
【０２７６】
４２０．７ｇのラテックス１ＨＭＬ（固形分換算）、イオン交換水９００ｇと、１６６ｇの着色剤分散液１とを、温度センサー、冷却管、窒素導入装置、攪拌装置を取り付けた反応容器（四つ口フラスコ）に入れ攪拌した。内温を３０℃に調整した後、この溶液に５モル／リットルの水酸化ナトリウム水溶液を加えてｐＨを８〜１０．０に調整した。
【０２７７】
次いで、塩化マグネシウム６水和物１２．１ｇをイオン交換水１０００ｍｌに溶解した水溶液を、攪拌下、３０℃にて１０分間かけて添加した。３分間放置した後に昇温を開始し、この系を６〜６０分間かけて９０℃まで昇温した。その状態で、「コールターカウンターＴＡ−II」にて会合粒子の粒径を測定し、個数平均粒径が４〜７μｍになった時点で、塩化ナトリウム８０．４ｇをイオン交換水１０００ｍｌに溶解した水溶液を添加して粒子成長を停止させ、さらに、熟成処理として液温度８５〜９８℃にて２〜１２時間にわたり加熱攪拌することにより融着を継続させた。その後、３０℃まで冷却し、塩酸を添加してｐＨを２．０に調整し、攪拌を停止した。生成した会合粒子を濾過し、４５℃のイオン交換水で繰り返し洗浄し、その後、４０℃の温風で乾燥して着色粒子１を得た。
【０２７８】
ここで、着色粒子１の製造にあたり、上記記載の凝集工程のｐＨ、熟成処理工程の温度、熟成時間、撹拌強度を制御して離型剤、着色剤分散状態、及び形状および形状係数の変動係数を制御し、さらに液中分級により、粒径および粒度分布の変動係数等を表１に示すように調整した。
【０２７９】
（比較用着色粒子１〜７の製造）
着色粒子１の製造にあたり、上記記載の凝集工程のｐＨ、熟成処理工程の温度、熟成時間、撹拌強度を制御して離型剤、着色剤分散状態、及び形状および形状係数の変動係数を制御し、さらに液中分級により、粒径および粒度分布の変動係数等を表１に示すように調整した以外は同様にして、比較用の着色粒子１〜７を製造した。
【０２８０】
（着色粒子２、３の製造）
着色粒子１の製造において、ラテックス１ＨＭＬの代わりにラテックス２ＨＭＬを使用し、また、Ｃ．Ｉ．ピグメント・レッド１２２のかわりにピグメントイエロー１８０を使用し表１に示す特性を有する着色粒子２を製造した。
【０２８１】
また、着色粒子１の製造において、ラテックス１ＨＭＬの代わりにラテックス３ＨＭＬを使用し、Ｃ．Ｉ．ピグメント・レッド１２２のかわりにフタロシアニン顔料（ＢＡＳＦ社製、ＰＢ−ＦＡＳＴ ＢＬＵＥ）を使用し、表１に示す特性を有する着色粒子３を製造した。
【０２８２】
【表１】

【０２８３】
《本発明の静電荷像現像用トナー粒子１〜５及び比較の静電荷像現像用トナー粒子１〜１３の作製》
以上のようにして得られた着色粒子１〜３及び比較用着色粒子１〜７の各々に、表２に示す疎水性針状チタン（ノルマルブチルトリメトキシシランにより疎水化処理）１．０質量部、および／または、シリカ（爆燃法により製造されたもの、ヘキサメチルシラザンにより疎水化処理）０．８質量部を添加し、１０リットルヘンシェルミキサーの回転翼の周速を３０ｍ／ｓに設定し混合した。尚、針状チタンと爆燃法により製造されたシリカ粒子の両方を添加する場合は、チタン粒子を添加して１０分混合した後、爆燃法により製造されたシリカ粒子を添加し１５分追加混合し、本発明の静電荷像現像用トナー粒子１〜５、比較用の静電荷像現像用トナー粒子１〜１３を各々得た。ここで、前記記載のトナー粒子の各々を調製するにあたり、表３に示すように、トナー粒子のＢＥＴ比表面積、エステルワックスの脂肪酸炭素数、アルコール炭素数、ボロノイ多角形の面積の平均値、変動係数、ボロノイ多角形の面積（１６００００ｎｍ²の成分（％））などを調整した。
【０２８４】
また、着色粒子から本発明及び比較の静電荷像現像用トナー粒子の各々を作製する過程において、前記記載の各々のトナー粒子の母体となる各々の着色粒子は、外部添加剤の添加等により、その形状および粒径は変化しない。
【０２８５】
【表２】

【０２８６】
【表３】

【０２８７】
《キャリアの製造》
（フェライト芯材の製造）
ＭｎＯを１８ｍｏｌ％、ＭｇＯを４ｍｏｌ％、Ｆｅ₂Ｏ₃を７８ｍｏｌ％を、湿式ボールミルで２時間粉砕、混合し乾燥させた後に、９００℃で２時間保持することにより仮焼成し、これをボールミルで３時間粉砕しスラリー化した。分散剤及びバインダーを添加し、スプレードライヤーにより造粒、乾燥し、その後１２００℃、３時間本焼成を行い、抵抗４．３×１０⁸Ωのフェライト芯材粒子を得た。
【０２８８】
（被覆用樹脂の製造）
界面活性剤として炭素数１２のアルキル基を有するベンゼンスルホン酸ナトリウムを用いた水溶液媒体中の濃度を０．３質量％とした乳化重合法により、シクロヘキシルメタクリレート／メチルメタクリレート（共重合比５／５）の共重合体を合成し、体積平均一次粒径０．１μｍ、質量平均分子量（Ｍｗ）２００，０００、数平均分子量（Ｍｎ）９１，０００、Ｍｗ／Ｍｎ＝２．２、軟化点温度（Ｔｓｐ）２３０℃及びガラス転移温度（Ｔｇ）１１０℃樹脂微粒子を得た。
【０２８９】
尚、前記樹脂微粒子は、乳化状態において、水と共沸し、残存モノマー量を５１０ｐｐｍとした。次に、フェライト芯材粒子１００質量部と、前記樹脂微粒子２質量部とを、撹拌羽根付き高速撹拌混合機に投入し、１２０℃で３０分間撹拌混合して、機械的衝撃力の作用を使用して個数平均粒径６１μｍの樹脂被覆キャリアを得た。
【０２９０】
《現像剤の製造》
上記記載の静電荷像現像用トナー粒子１〜５、比較の静電荷像現像用トナー粒子１〜１３の各々と前記記載のキャリアとを混合し、表４に示すように、静電荷像現像用トナー濃度が６質量％の現像剤試料１〜１８を各々、調製した。
【０２９１】
《現像剤の評価方法》
上記のようにして得られた現像剤試料１〜１８の各々を図５に記載の、画像形成プロセスを有するデジタル複写機に各現像剤を搭載し低温低湿環境下（温度１０℃、相対湿度２０％）、および高温高湿環境下（温度３３℃、相対湿度８０％）において、下記に示すようにハーフトーンの均一性、微細ドットのチリ、転写率を評価した。また、画素率６５％の画像を１０万枚形成する実写テストを行うことにより、転写体のフィルミングについて評価した。
【０２９２】
尚、下記記載の評価を行うに当たり、デジタル複写機の設定条件は下記のように調整した。
【０２９３】
（帯電条件）
帯電器；ローラー帯電器、初期帯電電位を−７５０Ｖ
（露光条件）
露光部電位を−５０Ｖにする露光量に設定
（現像条件Ｊ）
ＤＣバイアス；−５５０Ｖ
転写ベルトとしては下記「転写ベルト」を用いた。「転写ベルト」は、ポリイミドフィルム（表面抵抗１０１４Ω、厚さ２０μｍの高抵抗フィルム）の上に、フッ素系樹脂に導電剤を添加して表面抵抗を７×１０⁶Ωとした１０μｍの厚さの離型層を設けてなるエンドレスフィルム。
【０２９４】
（ハーフトーンの均一性）
感光体フィルミング、転写性変動によるによるハーフトーン画像の均一性を評価した。ランクを下記として評価した。
【０２９５】
ランクＡ：ムラの無い均一な画像（良好）
ランクＢ：スジ状の薄いムラが１本存在（実用上問題なし）
ランクＣ：スジ状の薄いムラが数本存在（実用不可）
ランクＤ：スジ状のはっきりしたムラが数本以上存在（不良）
（微細ドットのチリ）
画像全面に１０％網点画像を形成し、ルーペにてドット周辺のチリを観察し、下記のようにランク評価を行った。
【０２９６】
◎：チリがほとんど検知できない
○：微かにチリがあるが、注視しなければ気づかない程度（実用可）
×：チリが容易に検知できるもの（実用不可）
（転写率の評価）
下記式（１）により転写率（％）を求め、下記のようにランク評価した。
【０２９７】
式（１）
転写率（％）＝｛１−（回収トナーの質量／消費トナーの質量）｝×１００
◎：転写率９９．５％を越える（極めて良好）
○：９９．０〜９９．５％（良好）
△：９５．０〜９９．０％未満（実用不可）
×：９５．０％未満（不良）
（転写体フィルミングの評価）
目視観察でフィルミングの有無を判定した。
【０２９８】
未発生：転写体に曇りがなく、全くフィルミング確認されない
発生 ：転写体にフィルミングが確認できる
得られた評価結果を表４に示した。
【０２９９】
【表４】

【０３００】
表４から、比較と比べて本発明の試料は、ハーフトーンの均一性が良好であり、微細ドットのチリが無く、転写率、転写体のフィルミング等の特性にも優れていることが明らかである。
【０３０１】
【発明の効果】
本発明により、ハーフトーンの均一性が良好であり、微細ドットのチリが無く、転写率、転写体のフィルミング等の特性にも優れている静電荷像現像用トナーを提供することが出来た。
【図面の簡単な説明】
【図１】（ａ）は、角のないトナー粒子の投影像を示す説明図であり、（ｂ）および（ｃ）は、それぞれ角のあるトナー粒子の投影像を示す説明図である。
【図２】本発明に用いられる、海島構造を有するトナー粒子をボロノイ多角形によって分割した概略断面図である。
【図３】本発明に用いられる、海島構造を有するトナー粒子の一例を示す概略断面図である。
【図４】転写ロールを用いた画像形成装置の一例を示す概略断面図。
【図５】転写ベルトを用いた画像形成装置の一例を示す概略断面図。
【図６】転写ベルトを用いた定着器の構成断面図。
【符号の説明】
１０ 感光体
１１ 帯電器
１２ 像露光光
１３ 現像器
１４ 分離極
１５ 転写ロール
１６ バイアス電源
１７ クリーニングブレード
１８ 除電ランプ
１９ 給紙ローラ
２０ 定着器
Ｐ 転写材
Ｐａ、Ｐｂ、Ｐｃ、Ｐｄ 画像形成ユニット
１ａ、１ｂ、１ｃ、１ｄ 感光体
２ａ、２ｂ、２ｃ、２ｄ 潜像形成部
３ａ、３ｂ、３ｃ、３ｄ 現像部
４ａ、４ｂ、４ｃ、４ｄ 転写放電部
５ａ、５ｂ、５ｃ、５ｄ クリーニング器
６ａ、６ｂ、６ｃ、６ｄ 帯電器
２１ 転写ベルト
２２ａ、２２ｂ、２２ｃ、２２ｄ 分離除電放電器
２３ 定着装置
２４ クリーニング器
２５ 排出口
８４ 加熱体
８５ アルミナ基板
８６ 抵抗材料
８７ 検温素子
８８ フィルム
８９ 駆動ローラー
９０ 従動ローラー
９１ 繰り出し軸
９２ 巻き取り軸
９３ 未定着トナー像
９４ 転写材
９５ 加圧ローラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic image developing toner, a method for producing an electrostatic image developing toner, and an image forming method.
[0002]
[Prior art]
Today, the electrostatic latent image developing method represented by electrophotography is widely used in image forming methods such as printers, copiers, and facsimiles as a high-quality method that can stably obtain high-quality images at high speed. However, there are still some problems.
[0003]
For example, in a conventional toner prepared by a pulverization method, the material dispersed in the toner is unevenly present on the fracture surface, and the surface property between the toners is difficult to be constant, and variations in the transfer process are likely to occur. However, there is a problem that color reproducibility as a color image tends to be lowered.
[0004]
On the other hand, the electrostatic latent image developing toner is desired to have a small particle size from the viewpoint of high image quality. In recent years, polymerization toner has been actively developed as a method for producing a small particle size toner. In this polymerization method, resin particles and, if necessary, colorant particles are associated or salted out, agglomerated, and fused to prepare an irregularly shaped toner, or a radically polymerizable monomer and a colorant are dispersed. Then, there is a method in which droplets are dispersed in an aqueous medium or the like so as to have a desired toner particle size, and suspension polymerization is performed.
[0005]
However, since the toner particles produced by applying the suspension polymerization method can form a spherical toner having a uniform surface property, the uniformity among the toners is high, but the shape is spherical, so the latent particles are latent. Since the adhesion to the image carrier is increased, there is a problem in that the transferability tends to be lowered.
[0006]
Therefore, the resin particles polymerized in an aqueous medium containing a surfactant are produced by being treated with a flocculant having a critical aggregation concentration equal to or higher than the resin particles and an organic solvent that is infinitely soluble in water. A non-spherical particle is disclosed in JP-A-11-194540.
[0007]
In the technique described above, by using a divalent or trivalent metal salt as the aggregating agent, an image having excellent shape uniformity and charge amount uniformity and high sharpness can be obtained. The presence of a valent metal salt raises the Kraft point of the surfactant and forms a slightly soluble precipitate in water. This precipitate is present in a state where the colored particles, that is, the toner adheres to the toner after the toner is separated from the aqueous medium, the fog is likely to occur under high temperature and high humidity, and the transferability is liable to deteriorate. there were.
[0008]
In particular, in order to achieve high image quality, it is preferable to adjust the toner particles to have a small particle diameter and to uniformize the shape of the toner particles. There are problems such as uniformity, generation of fine dots, reduction in transfer rate, and filming of the transfer body, and there has been a demand for a solution to the above problems.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner for developing an electrostatic charge image having good halftone uniformity, no dust of fine dots, and excellent properties such as transfer rate and filming of a transfer member. is there.
[0010]
[Means for Solving the Problems]
  The object of the present invention is as follows.6Achieved by.
[0011]
1. All toner particles including toner particles including a resin, a colorant, and an external additive, wherein the toner particles have a number average particle diameter of 2 to 10 μm and a shape factor in the range of 1.2 to 1.6 In the toner for developing an electrostatic charge image, the proportion of the particles is 65% by number or more, the variation coefficient of the shape factor of the toner particles is 16% or less, and the number variation coefficient in the number particle size distribution is 27% or less.
The surface of the toner particles has a major axis length ratio of 2 to 20 and a major axis length of 10 to 200 nm, or a circularity coefficient of 0.976 to 1. A toner for developing an electrostatic charge image, comprising hydrophobic metal oxide particles having a number average particle diameter of 1.000 and having a number average particle size of 35 to 140 nm.
[0012]
2. 2. The electrostatic image developing toner according to 1 above, wherein the metal oxide particles subjected to the hydrophobization treatment are silica particles.
[0013]
  3.3. The electrostatic image developing toner according to 1 or 2, wherein at least one of the external additives is metal oxide particles produced by a deflagration method.
[0014]
4). 4. The electrostatic image developing toner according to 3 above, wherein the metal oxide particles produced by the deflagration method are silica particles.
[0015]
  5).The toner particles are produced through a process of aggregating and fusing resin particles in an aqueous medium, and the residual surfactant content in the toner particles is 1-1000 ppm, and the content of divalent or trivalent metal element is 250. 5. The electrostatic charge as described in any one of 1 to 4 above, wherein the toner particles have titanium oxide fine particles having a surface treatment of 20000 ppm and a water-soluble component amount of 2 to 1800 ppm. Toner for image development.
[0016]
6). 6. The toner for developing an electrostatic charge image according to any one of 1 to 5, wherein a ratio of the toner particles having no corners in the toner particles is 50% by number or more.
[0018]
  7).The toner particles having a resin obtained by polymerizing a polymerizable monomer in an aqueous medium.6The toner for developing an electrostatic image according to any one of the above.
[0019]
  8).BET specific surface area of toner particles is 1.1 to 3.5 g / m²1 to 3 above,7The toner for developing an electrostatic image according to any one of the above.
[0020]
  9.In a cross-sectional photograph obtained by photographing the toner particles with a transmission electron microscope, the average value of the area of the Voronoi polygon at the center of gravity of the low-luminance island is 20,000 to 120,000 nm.²The coefficient of variation is 25% or less.8The toner for developing an electrostatic image according to any one of the above.
[0021]
  10.In a cross-sectional photograph obtained by photographing the toner particles with a transmission electron microscope, the average value of the area of the Voronoi polygon at the center of gravity of the low-luminance island is 40000-100,000 nm.²The coefficient of variation is 20% or less.9The toner for developing an electrostatic image according to any one of the above.
[0022]
  11.In a cross-sectional photograph obtained by photographing the toner particles with a transmission electron microscope, the average value of the area of the Voronoi polygon at the center of gravity of the low-luminance island is 20,000 to 120,000 nm.²160000 nm²3 to 20% of the above components,10The toner for developing an electrostatic image according to any one of the above.
[0023]
  12The toner particles include a release agent, and the release agent includes an ester compound having a higher alcohol having 12 to 35 carbon atoms or a higher fatty acid having 12 to 35 carbon atoms.11The toner for developing an electrostatic image according to any one of the above.
[0024]
  13.1 to12In producing the toner for developing an electrostatic charge image according to any one of the above, the ratio of the length of the major axis to the length of the minor axis is 2 to 20 and the length of the major axis is 10 on the surface of the toner particles. Having a step of externally fixing and fixing titanium oxide fine particles of ~ 200 nm,
  An electrostatic charge having a roundness coefficient of 0.976 or more, a number average particle diameter of 35 to 140 nm, a step of externally fixing and fixing hydrophobized metal oxide particles manufactured by a deflagration method A method for producing a toner for image development.
[0025]
  14The metal oxide particles subjected to hydrophobization treatment are silica particles,13A method for producing a toner for developing an electrostatic image as described in 1.
[0026]
  15.1 to12In producing the toner for developing an electrostatic charge image according to any one of the above, it is obtained by agglomerating and fusing resin particles in an aqueous medium, containing 1 to 1000 ppm of a residual surfactant, To obtain toner particles by fixing titanium oxide fine particles containing 2 to 1800 ppm of a water-soluble component as at least one kind of external additive on the surface of colored particles containing 250 to 20000 ppm of a trivalent metal element. A method for producing a toner for developing an electrostatic charge image.
[0027]
  16.A toner image formed by developing an electrostatic latent image formed by charging and image exposure on an electrophotographic photosensitive member with toner for developing an electrostatic image is transferred to a transfer material using a contact transfer method, and thereafter An image forming method in which each step of separation, fixing and cleaning is repeated, wherein:12An image forming method comprising using the electrostatic image developing toner according to any one of the above.
[0028]
Hereinafter, the present invention will be described in detail.
In the present invention, by using the electrostatic charge image developing toner according to claims 1 to 13, there is a problem of conventional high-quality toner particles having a small particle size and a uniform shape, that is, uniform halftone. In addition, the problems such as the generation of dust, the generation of fine dots, the transfer rate decrease, and the occurrence of filming of the transfer body were simultaneously solved.
[0029]
The toner particles having a small particle size and a uniform shape having the above-mentioned problems are such that the ratio of the toner particle shape factor in the range of 1.2 to 1.6 is 65% by number or more, and the toner The variation coefficient of the shape factor of the particles is 16% or less, and the number variation coefficient in the number particle size distribution is 27% or less.
[0030]
The particle diameter of the electrostatic image developing toner of the present invention will be described.
As the particle diameter of the toner of the present invention, particles having a number average particle diameter of 2 to 10 [mu] m are used, but from the viewpoint of obtaining a high quality image, it is preferably adjusted to 3 to 8 [mu] m. This particle size can be controlled by the concentration of the aggregating agent, the amount of organic solvent added, the fusing time, and the polymer composition in the toner production method described in detail later.
[0031]
When the number average particle diameter is 2 to 10 μm, toner particles having high adhesion force that fly and adhere to the heating member and generate offset in the fixing process are reduced, and transfer efficiency is increased and halftone The image quality is improved, and the image quality of fine lines and dots is improved.
[0032]
The number average particle diameter of the toner can be measured using a Coulter Counter TA-II, Coulter Multisizer, SLAD 1100 (Laser Diffraction Particle Size Measuring Device manufactured by Shimadzu Corporation) or the like.
[0033]
In the present invention, a Coulter multisizer is used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting a particle size distribution and a personal computer are connected. The particle size distribution and the number average particle size were calculated by measuring the volume distribution of a toner of 1 μm or more (for example, 1 to 40 μm) using a 100 μm aperture in the Coulter Multisizer.
[0034]
The shape factor of the toner particles will be described.
The shape factor of the toner of the present invention is represented by the following formula and indicates the degree of roundness of the toner particles.
[0035]
Shape factor = ((maximum diameter / 2)²× π) / projection area
Here, the maximum diameter refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on the plane is sandwiched between two parallel lines. The projected area refers to the area of the projected image of the toner particles on the plane.
[0036]
In the present invention, this shape factor is obtained by taking a photograph in which the toner particles are magnified 2000 times with a scanning electron microscope, and then using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph. It was measured by performing analysis. At this time, the shape factor of the present invention was measured by the above formula using 100 toner particles.
[0037]
The method for controlling the shape factor is not particularly limited. For example, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy due to impact force in a gas phase, or a method in which a toner is not dissolved in a solvent and a swirl flow is applied. To prepare a toner having 65% by number or more of toner particles having a shape factor in the range of 1.2 to 1.6, and adding this to a normal toner so as to be within the range of the present invention. There is a way to do it. In addition, the entire shape is controlled at the stage of adjusting the so-called polymerization toner, and the toner whose shape factor is in the range of 1.2 to 1.6 is adjusted to 65% by number or more is similarly converted to a normal toner. The method of adding and adjusting is mentioned.
[0038]
The variation coefficient of the shape factor of the toner particles will be described.
“Variation coefficient of shape factor”, which is a variable indicating the uniform shape of toner particles, is calculated from the following equation.
[0039]
Variation coefficient of toner shape factor = (S1 / K) × 100 (%)
In the formula, S1 represents the standard deviation of the shape factor of 100 toner particles, and K represents the average value of the shape factor.
[0040]
As a basic condition for achieving high image quality, a toner having a shape factor of 16% or less is used as the coefficient of variation of the shape factor of the toner particles according to the present invention. The coefficient of variation is adjusted to 14% or less.
[0041]
In order to uniformly control the shape factor of the toner and the variation coefficient of the shape factor without variation in lots, the resin particles (polymer particles) constituting the toner of the present invention are prepared (polymerized), and the resin particles are melted. In the process of controlling the attachment and shape, an appropriate process end time is determined while monitoring the characteristics of the toner particles (colored particles) being formed.
[0042]
Monitoring means that a measuring device is incorporated in-line, and process conditions are controlled based on the measurement result. That is, in the case of polymerization toner formed by incorporating shape measurement in-line, for example, by associating or fusing resin particles in an aqueous medium, the shape and particle size are sequentially sampled during the fusing process. The reaction is stopped when the desired shape is obtained.
[0043]
Although it does not specifically limit as a monitoring method, The flow type particle image analyzer FPIA-2000 (made by Toa Medical Electronics Co., Ltd.) can be used. This apparatus is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field, and the shape is measured continuously, and the reaction is stopped when the desired shape is obtained.
[0044]
The number particle size distribution and number variation coefficient of the toner particles will be described.
The “number variation coefficient in the number particle size distribution”, which is one variable indicating the uniform shape of the toner particles, is measured with a Coulter counter TA or Coulter Multisizer (manufactured by Coulter Co., Ltd.). In the present invention, a Coulter Multisizer is used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the particle size distribution and a personal computer are connected. The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of toners of 1 μm or more were measured to calculate the particle size distribution and the number average particle size. The number particle size distribution represents the relative frequency of the toner particles with respect to the particle size, and the number average particle size represents the median diameter in the number particle size distribution. The “number variation coefficient in the number particle size distribution” of toner (hereinafter referred to as toner number variation coefficient) is calculated from the following equation.
[0045]
Toner number variation coefficient = (S2 / Dn) × 100 (%)
In the formula, S2 represents the standard deviation in the number particle size distribution, and Dn represents the number average particle size (μm).
[0046]
In the present invention, as basic characteristics of the toner, it is necessary that the charge amount distribution is sharp and the transfer efficiency is high. However, the toner number variation coefficient described above is adjusted to 27% or less. This is an essential requirement. Further, when the toner adjusted as described above is used in an image forming apparatus, the charging characteristics of the toner are stabilized, and incidental effects such as poor occurrence of cleaning failure are exhibited.
[0047]
The method for controlling the number variation coefficient in the toner is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for reducing the number variation coefficient. As a method of classifying in this liquid, there is a method of separating and collecting toner particles according to a difference in sedimentation speed caused by a difference in toner particle diameter by using a centrifuge and controlling the rotation speed.
[0048]
In particular, when a toner is produced by a suspension polymerization method or the like, a classification operation is essential in order to make the number variation coefficient in the number particle size distribution 27% or less. In the suspension polymerization method, it is necessary to disperse a polymerizable monomer in an oil droplet having a desired size as a toner in an aqueous medium before polymerization. That is, mechanical shearing by a homomixer or homogenizer is repeated for large oil droplets of a polymerizable monomer to reduce the oil droplets to the size of toner particles. In the method using shearing, the number particle size distribution of the obtained oil droplets is wide, and therefore the particle size distribution of the toner obtained by polymerizing the oil droplets is also wide. For this reason, classification operation is essential.
[0049]
Further, the toner according to the present invention has a natural logarithm lnD on the horizontal axis when the particle diameter of the toner particles is D (μm), and the horizontal axis is divided into a plurality of classes at intervals of 0.23. In the histogram showing the particle size distribution, the sum (M1) of the relative frequency (m1) of the toner particles included in the most frequent class and the relative frequency (m2) of the toner particles included in the most frequent class after the most frequent class. ) Is preferably 70% or more.
[0050]
When the sum (M) of the relative frequency (m1) and the relative frequency (m2) is 70% or more, the dispersion of the particle size distribution of the toner particles becomes narrow. Therefore, selective development can be performed by using the toner in the image forming process. Can be reliably suppressed.
[0051]
In the present invention, the histogram showing the particle size distribution based on the number is a natural logarithm lnD (D: particle size of individual toner particles) having a plurality of classes (0 to 0.23: 0.23) at intervals of 0.23. 0.46: 0.46-0.69: 0.69-0.92: 0.92-1.15: 1.15-1.38: 1.38-1.61: 1.61-1. 84: 1.84 to 2.07: 2.07 to 2.30: 2.30 to 2.53: 2.53 to 2.76, and so on). This histogram was analyzed by a particle size distribution analysis program installed in the computer by transferring the particle size data of the sample measured by the Coulter Multisizer to the computer via the I / O unit according to the following conditions. Is.
[0052]
"Measurement condition"
(1) Aperture: 100 μm
(2) Sample preparation method: Electrolyte [ISOTON R-11 (manufactured by Coulter Scientific Japan)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) was added and stirred, and 10-20 mg of measurement sample was added thereto. Add This system is prepared by dispersing for 1 minute with an ultrasonic disperser.
[0053]
In the toner according to the present invention, “toner particles having no corners” are preferably used as the particle shape from the viewpoint of reducing aggregation of toner particles. The “toner particles without corners” will be described with reference to FIG.
[0054]
In the toner according to the present invention, the proportion of toner particles having no corners in the toner particles constituting the toner is preferably 50% by number or more, and more preferably 70% by number or more.
[0055]
When the ratio of the toner particles having no corners is 50% by number or more, voids in the transferred toner layer (powder layer) are reduced, fixing property is improved, and offset is hardly generated. In addition, toner particles that easily wear and break and toner particles having a portion where charges are concentrated are reduced, the charge amount distribution becomes sharp, the chargeability is stable, and good image quality can be formed over a long period of time.
[0056]
Here, the “toner particles having no corners” means toner particles having substantially no protrusions that concentrate electric charges or protrusions that easily wear due to stress. Specifically, the following toner particles are used. Is called toner particles having no corners. That is, as shown in FIG. 1A, when the major axis of the toner particle T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particle T at one point. A case where the circle C does not substantially protrude outside the toner T when the inner side is rolled is referred to as “toner particles having no corners”. “A case where the protrusion does not substantially protrude” refers to a case where the protrusion having the protruding circle is one or less. The “major diameter of toner particles” refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on a plane is sandwiched between two parallel lines. FIGS. 1B and 1C show projected images of toner particles having corners, respectively.
[0057]
The ratio of toner particles having no corners was measured as follows. First, an enlarged photograph of the toner particles is taken with a scanning electron microscope, and further enlarged to obtain a 15,000 times photographic image. The photographic image is then measured for the presence or absence of the corners. This measurement was performed on 100 toner particles.
[0058]
A method for obtaining toner having no corners is not particularly limited. For example, as described above as a method for controlling the shape factor, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy by impact force in a gas phase, or a toner is dissolved. It can be obtained by adding in a solvent that does not, and applying a swirling flow.
[0059]
The external additive used for the toner according to the present invention will be described.
The toner particle according to claim 1 has a small particle size (2 to 10 μm) and a surface of the toner particle having a uniform shape, the length of the long axis relative to the length of the short axis as an external additive. The titanium oxide fine particles having a ratio of 2 to 20 and a length of the major axis of 10 to 200 nm, or a hydrophobicity treatment having a circularity coefficient of 0.976 to 1.000 and a number average particle size of 35 to 140 nm It has been found that the effects described in the present invention can be obtained by preparing to have metal oxide particles.
[0060]
The titanium oxide fine particles according to the present invention will be described.
As the titanium oxide fine particles according to the first aspect of the present invention, acicular titanium oxide fine particles are preferably used.
[0061]
Here, the needle shape is defined as the ratio of the length of the long axis to the length of the short axis of the titanium fine particles in the range of 2 to 20 and the length of the long axis in the range of 10 to 200 nm. More preferably, the ratio of the length of the major axis to the length of the shaft is 4 to 16, and the length of the major axis is in the range of 35 to 155 nm.
[0062]
By externally adding the acicular titanium oxide fine particles as described above to the toner particles, contamination of the contact charging member or the contact transfer member can be remarkably suppressed, and a stable image can be obtained over a long period of time.
[0063]
The titanium oxide fine particles are added so as to have a blending amount of 0.1 to 5% by mass, more preferably 0.4 to 2% by mass with respect to the toner particles according to the present invention. You may use together with an additive.
[0064]
An example of the method for producing titanium oxide fine particles according to the present invention is as follows. Titanium obtained by a known production method such as a method using metatitanic acid obtained by a sulfuric acid method or hydrolyzing titanium tetrachloride or alkoxide. In a so-called flux method, a specific surface area of 20 to 120 m is used as a titanium source in a so-called flux method in which a source, an alkali metal source and an oxylin compound are mixed, and the mixture is preferably fired at 700 to 1000 ° C²/ G of fine particle rutile type titanium oxide. As the alkali metal source, alkali metal chlorides such as sodium and potassium, carbonates or oxyacids can be used. Examples of oxyphosphorus compounds that can be used include sodium, potassium, and ammonium phosphates, phosphorus oxides, and oxyacids.
[0065]
The firing temperature when firing the above mixture is 700 to 1000 ° C, preferably 800 to 900 ° C. When the temperature is lower than 700 ° C., it is difficult to form a needle shape, and when the temperature is 1000 ° C. or higher, the sintering is not preferable. The obtained fired product is subsequently dispersed and washed in water, but the aqueous solution may be heated to facilitate removal of soluble salts, or may be forcibly removed with an acid or alkali.
[0066]
Further, from the viewpoint of suppressing the humidity fluctuation of charging of the toner particles according to the present invention and maintaining good transferability, the titanium oxide fine particles according to claim 2 preferably have a water-soluble component amount of 2 to 1800 ppm. Although used, it is more preferably 20 to 1200 ppm.
[0067]
The amount of the water-soluble component can be adjusted by the cleaning conditions after firing in the titanium production process.
[0068]
As a water-soluble component, K contained in the conditioner and flocculant used in the manufacturing process⁺, Na⁺, Li⁺, Mg²⁺, PO_Four ^2-, SO_Four ^2-, Cl^-Etc. The water-soluble component is measured by boiling 5 g of titanium dioxide in 250 ml of water, evaporating and drying 100 ml of the filtrate obtained by filtering after cooling, and weighing the remaining amount.
[0069]
The measurement is performed with reference to the method described in JIS K5116-1973. Moreover, the amount of water-soluble components is in accordance with the above-mentioned JIS, and the remaining amount is expressed by mass% with respect to the original titanium dioxide.
[0070]
The metal oxide particles according to the present invention will be described.
From the viewpoint of obtaining the effects described in the present invention, the metal oxide particles used in the invention of claim 1 have a circularity coefficient of 0.976 to 1.000 and a number average particle diameter of 35 to 140 nm. It is necessary to use the metal oxide particles.
[0071]
From the viewpoint of reducing the occurrence of scratches on the photoreceptor and improving the uniformity of the halftone of the image, the circularity coefficient of the metal oxide particles according to the present invention is preferably 0.982 to 0.996. The circularity coefficient is an index representing a correlation coefficient with a perfect circle shape. Here, the circularity coefficient is calculated using a flow type particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.). can do.
[0072]
For example, when metal oxide particles having a circularity coefficient of 0.982 to 0.996 are produced by a deflagration method, the metal oxide particles rapidly burn silicon and oxygen at a reaction rate of about several hundreds of meters per second. It is preferably generated by reaction, and from the viewpoint of improving the fluidity of toner particles and ensuring stable transfer performance, the bulk density is preferably adjusted to 300 g / liter or more.
[0073]
In general, the metal oxide particles obtained by this method have a density of 2.1 mg / mm.^ThreeIt has a large spherical shape with a smooth surface. In addition, the bulk density of the colloidal silica by a normal hydrolysis method is 50 to 200 g / liter.
[0074]
Further, from the viewpoint of improving transferability, reducing separation from toner particles, and preventing contamination of the charging member and the transfer member, the number average particle size of the metal oxide particles according to the present invention is 35 to 140 nm. However, those having a range of 50 to 110 nm are preferably used.
[0075]
Here, the number average particle size of the metal oxide particles can be measured using a Coulter Counter TA-II, Coulter Multisizer, SLAD1000 (a laser diffraction particle size measuring device manufactured by Shimadzu Corporation) or the like.
[0076]
As a means for obtaining particles having a high circularity coefficient, the metal oxide particles according to the present invention are preferably produced using a deflagration method.
[0077]
The metal oxide fine particles using the deflagration method can be produced with reference to, for example, the method described in JP-A-60-255602. Here, the deflagration method is a method of obtaining metal oxide particles by instantaneously oxidizing the metal powder in a state where the metal powder is dispersed in a gas atmosphere. Specifically, first, a reaction gas containing oxygen is filled in a reaction vessel, and metal powder is dispersed in the reaction gas to form a high-concentration dust cloud. Next, ignition is performed using an appropriate ignition source such as arc, plasma, chemical flame, etc., so that the metal powder detonates and a cloud of metal oxide fine particles is generated.
[0078]
In this case, the particle size of the metal powder used for deflagration is desirably as small as possible, and is usually 140 nm or less. Examples of the material of the metal powder include aluminum, silicon, manganese, niobium, zirconium, titanium, magnesium, and iron, among which silicon is preferable.
[0079]
Among the metal oxide particles described above, silica particles are particularly preferably used. In addition, as a method for forming a dust cloud of metal powder, a method in which the gas forming the reaction gas is accompanied by the metal powder and fed into the reaction vessel is preferably employed. Metal concentration is at least 20 g / m^ThreeNormally 500g / m^ThreeOr more, more preferably 1000 g / m^ThreeAs described above, the concentration of the metal powder in the dust cloud is preferably higher for stable ignition.
[0080]
When such a dust cloud of metal powder is ignited, thermal energy is applied to the surface of the metal powder, the surface temperature of the metal powder rises, and metal vapor spreads from the metal powder surface to the surroundings. This metal vapor mixes with the reaction gas to produce an ignition flame. Then, the generated metal vapor and the reaction gas are mixed and ignited and propagated in a chain. At this time, the metal powder itself is also ruptured and scattered to promote flame propagation. After combustion, the metal oxide gas is naturally cooled to grow metal oxide particles, and spherical or polyhedral fine particles having a number average particle size of 0.01 to 20 μm are usually obtained.
[0081]
Since the metal oxide fine particles synthesized by the deflagration are particles grown in a natural cooling process, they are characterized by rich surface activity compared to conventional spherical particles melted and spheroidized at high temperature. For example, spherical silica synthesized by this method has a large amount of active silanol groups on the surface.
[0082]
The metal oxide fine particles synthesized by deflagration are preferably surface-treated with an organosilicon compound for improving fluidity and chargeability. As a surface treatment method, there is a method of applying a heat treatment after spraying an organic silicon compound directly on an inorganic powder using a wet treatment or a high-speed stirring device as conventionally known. In the present invention, as a more effective surface treatment method, the organosilicon compound is sprayed in the reaction vessel onto the metal oxide fine particles obtained immediately after the deflagration using the organosilicon compound generally used for the surface treatment. The method is recommended. According to this method, since the surface activity of the metal oxide fine particles is very high, the surface treatment is effectively performed.
[0083]
Examples of organosilicon compounds used for the surface treatment include silicone oils, preferably the following silane coupling agents, and these compounds or hydrolysates thereof are used alone or in combination of two or more. can do.
[0084]
CH_ThreeSi (OCH_Three)_Three,
(CH_Three)₂Si (OCH_Three)₂,
CH_Three(CH₂)₇Si (OCH_Three)_Three,
NH₂(CH₂)_ThreeSi (OCH_Three)_Three, HS (CH₂)_ThreeSi (OCH_Three)_Three,
(CH_Three)_ThreeSiNHSi (CH_Three)_Three,
CH₂= C (CH_Three) COOCH₂CH₂Si (OCH_Three)_Three
The amount of these organosilicon compounds used is determined by the specific surface area of the metal oxide fine particles and the area occupied by the molecules of the organosilicon compound, but usually 0.05 to 5% by mass of the metal oxide fine particles, preferably It is 0.1-1 mass%. In addition, when spraying these organosilicon compounds, a method of spraying the organosilicon compound as it is, or mixing and spraying with pure water, preferably pure water containing a strong base such as DBU, etc. is adopted. Can do.
[0085]
In addition, as the hydrophobic treatment of the metal oxide particles described above, a coating treatment with a metal oxide such as aluminum, silicon, or zinc, or a hydrophobic treatment with an organic substance such as various coupling agents or fatty acid compounds is performed. It is preferable.
[0086]
A silane coupling agent, which is an example of a coupling agent, is used for improving the degree of hydrophobicity, environment dependency, and fluidity, and may be water-soluble.
[0087]
Such silane coupling agents include chemical structural formula R_nSiX_4-n(In the formula, n is an integer of 0 to 3, R represents an organic group such as a hydrogen atom, an alkyl group and an alkenyl group, and X represents a hydrolytic group such as a chlorine atom, a methoxy group and an ethoxy group.) And any type of chlorosilane, alkoxysilane, silazane, and special silylating agent can be used, and alkoxysilane is particularly preferable. Examples of the alkoxysilane include vinyltrimethoxysilane, propyltrimethoxysilane, i-butyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, and n-dodecyltrimethoxy. Silane, phenyltrimethoxysilane, 3-glycoxypropyltrimethoxysilane and the like can be mentioned, and those having 2 to 10 carbon atoms in the hydrocarbon group are preferable. Of these, i-butyltrimethoxysilane and n-butyltrimethoxysilane are particularly preferable.
[0088]
Moreover, the said processing amount is 10-100 mass% with respect to 100 mass% of titanium oxide, Preferably it is the range of 20-70 mass%. When the treatment amount is 10% by mass or less, not only low hydrophobicity can be obtained, but also solid fixation occurs during drying, resulting in poor dispersion, and when it is 100% by mass or more, the decrease in specific surface area. Is not preferable.
[0089]
Hydrophobized silica particles and titanium oxide fine particles described above are used as external additives, and conventionally known inorganic fine particles and organic fine particles can also be used as external additives. These inorganic fine particles are preferably hydrophobic.
[0090]
The constituent materials of inorganic fine particles that can be used as external additives include silicon oxide, titanium oxide, aluminum oxide, zinc oxide, zirconium oxide, cerium oxide, tungsten oxide, antimony oxide, copper oxide, tellurium oxide, manganese oxide, and barium titanate. Strontium titanate, magnesium titanate, silicon nitride, carbon nitride, etc. are used.
[0091]
As specific examples of conventionally known silica particles, commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK manufactured by Hoechst Co., Ltd. -2150, H-200, commercially available products TS-720, TS-530, TS-610, H-5, and MS-5 manufactured by Cabot Corporation.
[0092]
Specific examples of conventionally known titanium fine particles include, for example, commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products MT-100S, MT-100B, and MT- manufactured by Teika Co., Ltd. 500BS, MT-600, MT-600SS, JA-1, commercial products manufactured by Fuji Titanium Co., Ltd. TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T, manufactured by Idemitsu Kosan Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT-OC and the like can be mentioned.
[0093]
Specific examples of the alumina fine particles used as the inorganic fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd. .
[0094]
Examples of the organic fine particles that can be used as the external additive include spherical fine particles having a number average primary particle diameter of about 10 to 2000 nm. Examples of the constituent material of the organic fine particles include polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer.
[0095]
Examples of the lubricant that can be used as an external additive include metal salts of higher fatty acids. Specific examples of the metal salts of such higher fatty acids include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate, and the like; zinc oleate, manganese oleate, iron oleate, olein Oleic acid metal salts such as acid copper and magnesium oleate; palmitate metal salts such as zinc palmitate, copper palmitate, magnesium palmitate and calcium palmitate; linoleic acid metal salts such as zinc linoleate and calcium linoleate; ricinol Examples thereof include ricinoleic acid metal salts such as zinc acid and calcium ricinoleate.
[0096]
The addition amount of the external additive is preferably about 0.1 to 5% by mass with respect to the toner.
The external additive adding process will be described.
[0097]
This step is a step of adding an external additive to the dried toner particles.
Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.
[0098]
Further, the toner particles according to claim 3, similarly to the toner particles according to claim 1, have the step of causing the toner particles having the uniform shape as described above to aggregate and fuse the resin particles in an aqueous medium. The amount of the residual surfactant in the toner particles is 1-1000 ppm, the content of the divalent or trivalent metal element is 250-20000 ppm, and the amount of water-soluble component is one kind of the external additive. The effect described in the present invention can be obtained by preparing the surface of the toner particle so that the surface is treated with titanium oxide fine particles (also referred to as adhesion). It was found that the adsorption of water molecules on the surface is not biased, the transferability is improved, and particularly the change in transferability due to humidity fluctuation is significantly reduced.
[0099]
According to the aspect of the invention defined in claim 3, it has been found that the transferability is improved, especially the change in transferability due to humidity fluctuation is reduced.
[0100]
Furthermore, in the invention according to claim 3, the charge holding function of the toner is maintained in a good state, the fog generation under high temperature and high humidity is suppressed, and the charge amount is increased under low temperature and low humidity from the viewpoint of improving transferability From the viewpoint of stabilizing the development amount and stabilizing the development amount, the surfactant content is 1-1000 ppm, preferably 5-500 ppm, and more preferably 7-100 ppm.
[0101]
As the surfactant according to the present invention, it is preferable to add and mix a surfactant in the aqueous medium. Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene Nonionic surfactants such as glycols, alkylphenol ethylene oxide adducts, polyhydric alcohols and the like can be mentioned. Among these, an ionic surfactant is preferable, and an anionic surfactant and a cationic surfactant are more preferable. The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may use 2 or more types together.
[0102]
Specific examples of the anionic surfactant include fatty acid soaps such as potassium laurate, sodium oleate and sodium castor oil; sulfates such as octyl sulfate, lauryl sulfate, lauryl ether sulfate and nonylphenyl ether sulfate; lauryl sulfonate Sulfone such as sodium alkylnaphthalene sulfonate such as dodecylbenzene sulfonate, triisopropyl naphthalene sulfonate, dibutyl naphthalene sulfonate, naphthalene sulfonate formalin condensate, monooctyl sulfosuccinate, dioctyl sulfosuccinate, lauric acid amide sulfonate, oleic acid amide sulfonate Acid salts; lauryl phosphate, isopropyl phosphate, nonylphenyl ether Phosphoric acid esters such as phosphate; dialkyl sulfosuccinate salts such as sodium dioctyl sulfosuccinate, sodium lauryl sulfosuccinate 2, polyoxyethylene sulfo sulfosuccinate salts such as succinic acid lauryl disodium; and the like.
[0103]
Specific examples of the cationic surfactant include laurylamine hydrochloride, stearylamine hydrochloride, oleylamine acetate, stearylamine acetate, stearylaminopropylamine acetate, and other amine salts; lauryltrimethylammonium chloride, dilauryldimethylammonium Chloride, distearyl ammonium chloride, distearyl dimethyl ammonium chloride, lauryl dihydroxyethyl methyl ammonium chloride, oleyl bispolyoxyethylene methyl ammonium chloride, lauroylaminopropyldimethylethylammonium ethosulphate, lauroylaminopropyldimethylhydroxyethylammonium perchlorate, alkylbenzene dimethyl Ammonium chloride, alkylto Quaternary ammonium salts such as ammonium chloride; and the like.
[0104]
Specific examples of the nonionic surfactant include polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether and other alkyl ethers; Alkylphenyl ethers such as oxyethylene nonylphenyl ether; alkyl esters such as polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene oleate; polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, polyoxy Alkyl amines such as ethylene oleyl amino ether, polyoxyethylene soybean amino ether, polyoxyethylene beef tallow amino ether; Alkyl amides such as xylethylene lauric acid amide, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid amide; vegetable oil ethers such as polyoxyethylene castor oil ether, polyoxyethylene rapeseed oil ether; lauric acid diethanolamide, stearin Alkanolamides such as acid diethanolamide and oleic acid diethanolamide; sorbitan ester ethers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate And the like.
[0105]
Among these, surfactants particularly preferably used in the present invention are surfactants having a polyoxyethylene alkyl ether sulfate structure represented by the following general formula (1) and general formula (2).
[0106]
General formula (1)
R₁(OR₂)_nOSO_ThreeM
Where R₁Is an alkyl or arylalkyl group having 6 to 22 carbon atoms, R₂Represents an alkylene group having 2 to 6 carbon atoms. n represents an integer of 1 to 11, and M represents a monovalent metal element or ammonium ion.
[0107]
General formula (2)
R₁(OR₂)_nSO_ThreeM
Where R₁Represents an alkyl group having 6 to 22 carbon atoms or an arylalkyl group, and R₂Represents an alkylene group having 2 to 6 carbon atoms, and n represents an integer of 1 to 11. M represents a monovalent metal element or ammonium ion.
[0108]
In the general formulas (1) and (2), R₁Represents an alkyl group or arylalkyl group having 6 to 22 carbon atoms, preferably an alkyl group or arylalkyl group having 8 to 20 carbon atoms, more preferably an alkyl group or arylalkyl group having 9 to 16 carbon atoms. is there.
[0109]
R₁Examples of the alkyl group having 6 to 22 carbon atoms represented by: n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-undecyl group, n-hexadecyl group, cyclopropyl group , Cyclopentyl group, cyclohexyl group and the like.
[0110]
R₁Examples of the arylalkyl group represented by the formula include a benzyl group, a diphenylmethyl group, a cinnamyl group, a styryl group, a trityl group, and a phenethyl group.
[0111]
In the general formulas (1) and (2), R₂Represents an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms.
[0112]
R₂Examples of the alkylene group having 2 to 6 carbon atoms represented by: ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group and the like.
[0113]
In general formula (1), (2), n is an integer of 1-11, Preferably it is 2-10, More preferably, it is 2-5, Most preferably, it is 2-3.
[0114]
In the general formulas (1) and (2), examples of the monovalent metal element represented by M include sodium, potassium, and lithium. Of these, sodium is preferably used.
[0115]
Specific examples of the surfactants represented by the general formulas (1) and (2) are shown below, but the present invention is not limited thereto.
[0116]
Compound (101): C_TenH_{twenty one}(OCH₂CH₂)₂OSO_ThreeNa
Compound (102): C_TenH_{twenty one}(OCH₂CH₂)_ThreeOSO_ThreeNa
Compound (103): C_TenH_{twenty one}(OCH₂CH₂)₂SO_ThreeNa
Compound (104): C_TenH_{twenty one}(OCH₂CH₂)_ThreeSO_ThreeNa
Compound (105): C₈H₁₇(OCH₂CH (CH_Three))₂OSO_ThreeNa
Compound (106): C₁₈H₃₇(OCH₂CH₂)₂OSO_ThreeNa
In the present invention, the charge holding function of the toner is maintained in a good state, the occurrence of fogging at high temperature and high quality is suppressed, and from the viewpoint of improving transferability, the increase in charge amount at low temperature and low humidity is also suppressed, and the development amount From the viewpoint of stabilizing the content, the content of the surfactant represented by the general formulas (1) and (2) in the toner for developing an electrostatic charge image of the present invention is preferably 1 to 1000 ppm, More preferably, it is 5-500 ppm, Most preferably, it is 7-100 ppm.
[0117]
By incorporating the surfactant in the toner within the above-mentioned range, the charging property of the toner for developing an electrostatic charge image of the present invention is not affected by the influence of the environment and is always applied and maintained uniformly and stably. I can do it.
[0118]
The method for measuring the content of the surfactant represented by the general formulas (1) and (2) in the toner for developing an electrostatic charge image of the present invention is as follows.
[0119]
1 g of toner is dissolved in 50 ml of chloroform, the surfactant is extracted from the chloroform layer with 100 ml of ion-exchanged water, this chloroform layer is extracted once again with 100 ml of ion-exchanged water, and a total of 200 ml of extract (water layer) is reduced to 500 ml. Dilution, This diluted solution was used as a test solution, colored with methylene blue according to the method defined in JIS 33636, the absorbance was measured, and the content in the toner was measured from a separately prepared calibration curve.
[0120]
Moreover, the structure of the surfactant represented by the general formulas (1) and (2)¹The structure was analyzed by H-NMR.
[0121]
In addition, in the same manner as the surfactants described above, the charge retention function of the toner is maintained in a good state, fogging at high temperature and high quality is suppressed, and from the viewpoint of improving transferability, charging at low temperature and low humidity is also possible. From the viewpoint of suppressing the increase in the amount and stabilizing the development amount, the content of the divalent or trivalent metal element in the toner particles is required to be 250 to 20000 ppm, preferably 800 to 5000 ppm. .
[0122]
As a means for incorporating the metal element described above into the toner particles, in the step of aggregating and fusing the resin particles in the aqueous medium, a divalent or trivalent metal salt is used as the aggregating agent in the toner particles. You can capture.
[0123]
In the present invention, a metal salt is preferably used as a flocculant in the step of salting out, agglomerating, and fusing resin particles from a dispersion of resin particles prepared in an aqueous medium. Is to use a valent metal salt as a flocculant. The reason is that the divalent and trivalent metal salts have a smaller critical aggregation concentration (coagulation value or coagulation point) than the monovalent metal salts.
[0124]
The metal salt used as the aggregating agent (sometimes used as an aggregation terminator) will be described.
[0125]
Examples of the metal salt include monovalent metals such as alkali metal salts such as sodium, potassium and lithium, divalent metals such as alkaline earth metal salts such as calcium and magnesium, and divalent metals such as manganese and copper. Examples thereof include trivalent metal salts such as salt, iron and aluminum. Specific examples of these metal salts are shown below.
[0126]
Specific examples of the monovalent metal salt include sodium chloride, potassium chloride, lithium chloride and the like. Examples of the metal salt of the divalent metal include magnesium chloride, calcium chloride, calcium nitrate, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate and the like. Examples of the trivalent metal salt include aluminum chloride and iron chloride. These are appropriately selected according to the purpose.
[0127]
The above-mentioned critical aggregation concentration is an index relating to the stability of the dispersion in the aqueous dispersion, and indicates the concentration at which aggregation occurs when a flocculant is added. This critical coagulation concentration varies greatly depending on the latex itself and the dispersant. For example, it is described in Seizo Okamura et al., Polymer Chemistry 17,601 (1960), etc., and the value can be known by following these descriptions.
[0128]
As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ potential of the dispersion is measured, and the salt concentration at the point where the ζ potential starts to change is defined as the critical aggregation concentration. It is also possible to do.
[0129]
Examples of the divalent or trivalent metal element according to the present invention include divalent metals such as alkaline earth metals such as calcium and magnesium, divalent metals such as manganese and copper, and trivalent metals such as iron and aluminum. Etc. Specific examples of metal salts containing these metal elements are shown below.
[0130]
Examples of the metal salt of the divalent metal element include magnesium chloride, calcium chloride, calcium nitrate, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate and the like.
[0131]
Examples of the metal salt of the trivalent metal element include aluminum chloride and iron chloride. These are appropriately selected according to the purpose, and may be appropriately mixed and used.
[0132]
The polymer fine particle dispersion is treated with the metal salt described above according to the present invention so as to have a concentration equal to or higher than the critical aggregation concentration. At this time, as a matter of course, whether the metal salt is added directly or as an aqueous solution is arbitrarily selected according to the purpose. When added as an aqueous solution, the added metal salt must be equal to or higher than the critical aggregation concentration of the polymer particles with respect to the volume of the polymer particle dispersion and the total volume of the metal salt aqueous solution.
[0133]
The concentration of the metal salt used as the flocculant may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration.
[0134]
In addition, a dispersion liquid in which composite resin particles (the case where the particles have a multilayer structure or other constituents such as additives are included in the particles are referred to as composite resin particles) or colorant particles are dispersed. The temperature of the dispersion when adding the flocculant therein is preferably not higher than the glass transition temperature (Tg) of the composite resin particles, and specifically, preferably in the range of 5 to 55 ° C. Preferably it is set as 10 to 45 degreeC.
[0135]
When the temperature of the dispersion liquid when adding the flocculant is equal to or higher than the glass transition temperature (Tg) of the composite resin particles, it is difficult to control the particle size, and large particles are likely to be generated.
[0136]
In the salting out, agglomerating and fusing steps, when the temperature of the dispersion in which the composite resin particles and the colorant particles are dispersed is equal to or lower than the glass transition temperature (Tg) of the composite resin particles, the dispersion It is preferable to add the flocculant while stirring the liquid, and then immediately start heating the dispersion to a temperature equal to or higher than the glass transition temperature (Tg) of the composite resin particles.
[0137]
In the present invention, resin particles and a colorant are salted out, aggregated, and fused in an aqueous medium to obtain colored particles (referred to as toner particles in the present invention), and then the toner particles are separated from the aqueous medium. When performing, it is preferable to carry out at the temperature more than the craft point of the surfactant which exists in an aqueous medium, More preferably, it is carrying out in the temperature range of a craft point-(craft point +20 degreeC).
[0138]
The Kraft point is a temperature at which an aqueous solution containing a surfactant starts to become cloudy, and the Kraft point is measured as follows.
[0139]
<Measurement of craft point>
A solution was prepared by adding the actual amount of the flocculant to the aqueous medium, that is, the surfactant solution used in the salting out, agglomeration and fusion processes, and this solution was stored at 1 ° C. for 5 days. The solution was then gradually heated with stirring until clear. The temperature at which the solution becomes clear is defined as the Kraft point.
[0140]
In the present invention, the total value of the divalent (trivalent) metal element used as the flocculant and the monovalent metal element added as the aggregation terminator is preferably 350 to 35000 ppm.
[0141]
The residual amount of metal ions in the toner can be measured by using a fluorescent X-ray analyzer “System 3270” (manufactured by Rigaku Denki Kogyo Co., Ltd.) and using a metal species of a metal salt used as a flocculant (for example, calcium chloride). It can be determined by measuring the intensity of the fluorescent X-ray emitted from the derived calcium or the like. As a specific measurement method, a plurality of toners having a known content ratio of the flocculant metal salt are prepared, each toner 5g is pelletized, the content ratio (mass ppm) of the flocculant metal salt, and the metal type of the metal salt The relationship (calibration curve) with the fluorescent X-ray intensity (peak intensity) is measured. Next, the toner (sample) whose content of the flocculant metal salt is to be measured is similarly pelletized, and the fluorescent X-ray intensity from the metal species of the flocculant metal salt is measured. Amount "can be obtained.
[0142]
Regarding the external additive used for the toner according to claim 3, the above-mentioned external additives can be used in the same manner.
[0143]
The BET specific surface area of the toner particles according to the present invention will be described.
The toner particles according to the present invention have a BET specific surface area of 1.1 to 3.5 g / m.²And more preferably 1.3 to 2.7 g / m.²It is.
[0144]
When the toner particles have a BET surface area in the above-mentioned range, the external additive is fixed to an appropriate toner, so that the fluidity is excellent, and the effect of reducing the charge amount due to moisture adsorption can be obtained.
[0145]
The BET specific surface area was measured by a BET single point method using an automatic specific surface area measuring device GEMINI 2375 (manufactured by Shimadzu Corporation).
[0146]
An ester compound used as an example of a release agent in the toner particles according to the present invention will be described.
[0147]
If soft wax is present on the toner surface, the external additive is buried and transferability is lowered. In order not to contaminate the transfer member, an ester wax having a high hardness and a low melt viscosity is preferably used.
[0148]
The mold release agent contains at least one ester composed of a higher alcohol having 12 to 35 carbon atoms and / or a higher fatty acid having 12 to 35 carbon atoms, but the acid component is a higher fatty acid having 12 to 35 carbon atoms. In some cases, the alcohol component includes monoalcohols such as methyl, ethyl, propyl and butyl, glycols such as ethylene glycol and propylene glycol and multimers thereof, triols such as glycerin and multimers thereof, and pentaerythritol. Polyhydric alcohols such as sorbitan, cholesterol and the like are suitable. When the alcohol component is a polyhydric alcohol, the higher fatty acid may be a mono-substituted product or a poly-substituted product.
[0149]
Specific examples of the release agent include esters comprising a higher alcohol having 12 to 35 carbon atoms such as stearyl stearate, palmityl palmitate, behenyl behenate, stearyl montanate and the like and a higher fatty acid having 12 to 35 carbon atoms; Esters consisting of higher fatty acids having 12 to 35 carbon atoms such as butyl stearate, isobutyl behenate, propyl montanate, 2-ethylhexyl oleate and lower monoalcohols; montanic acid monoethylene glycol ester, ethylene glycol distearate, Monostearic glyceride, monobehenic acid glyceride, tripalmitic acid glyceride, pentaerythritol monobehenate, pentaerythritol dilinoleate, pentaerythritol trioleate, pentaerythritol tetrastearate, etc. Esters comprising higher fatty acids having 12 to 35 carbon atoms and polyhydric alcohols; diethylene glycol monobehenate, diethylene glycol dibehenate, dipropylene glycol monostearate, distearic acid diglyceride, tetrastearic acid triglyceride, hexabehenic acid tetraglyceride, deca Esters composed of higher fatty acids having 12 to 35 carbon atoms such as decaglyceride stearate and polyhydric alcohol multimers; carbons such as glycerol monoacetomonostearate, glycerol monoacetomonolinoleate, diglycerol monoacetodistearate Esters consisting of a higher fatty acid of 12 to 35 and a polyhydric alcohol monomer or multimer (which may contain a short-chain functional group); sorbitan monostearate, sorbitan dibehenate, Sorbitan higher fatty acid esters such as sorbitan trioleate; cholesteryl stearate, cholesteryl oleate, such as cholesterol higher fatty acid esters such as cholesteryl linoleate are preferably exemplified. In the present invention, among these release agents, those used in the examples described later are particularly preferred. These release agents may be used alone or in combination of two or more.
[0150]
The melting point of the release agent is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and particularly preferably 50 ° C. or higher, from the viewpoint of toner storage stability. The carbon number of the alcohol component and / or the acid component in the ester composed of a higher alcohol having 12 to 35 carbon atoms and / or a higher fatty acid having 12 to 35 carbon atoms used as the release agent is appropriately determined in consideration of the melting point. Can be determined.
[0151]
Among the ester compounds, a release agent particularly preferably used is an ester compound represented by the following general formula.
[0152]
General formula
R₁-(OCO-R₂)_n
In the formula, n represents an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.
[0153]
R₁, R₂Represents a hydrocarbon group which may have a substituent.
R₁: Carbon number = 1-40, preferably 1-20, more preferably 2-5
R₂: Carbon number = 1-40, preferably 16-30, more preferably 18-26
Hereinafter, as specific examples of the ester compound represented by the above general formula, exemplary compound 1) to exemplary compound 21) are shown, but the present invention is not limited thereto.
[0154]
[Chemical 1]

[0155]
[Chemical 2]

[0156]
The content ratio of the release agent constituting the toner for developing an electrostatic charge image of the present invention is usually 1 to 30% by mass, preferably 2 to 25% by mass, and more preferably 4 to 20% by mass.
[0157]
The release agent described above may further contain low molecular weight polypropylene (number average molecular weight = 1500-9000), low molecular weight polyethylene, or the like.
[0158]
As the toner particles of the present invention, particles having a sea-island structure in which a colorant or the like constitutes a separated phase in the binder resin phase are preferably used. The occupancy state of the island portion in the sea-island structure of toner particles is indicated by the area of a Voronoi polygon obtained by Voronoi division.
[0159]
Further, since the effects described in the present invention, such as an improvement in transfer rate, uniformity of halftone, and elimination of fine dot dust, are obtained, the toner particles according to the present invention are defined as follows. It is preferable that the average value of the area of the Voronoi polygon (also referred to as a Voronoi polyhedron) falls within a specific range. Here, the Voronoi polygon will be described.
[0160]
The area of the Voronoi polygon according to the present invention indicates the occupation state of the island portion in the toner particles. A Voronoi polygon or Voronoi polyhedron is, for example, a perpendicular bisector of adjacent points when many points are dispersed in space or on a plane, as described in the Iwanami Physical and Chemical Dictionary, By creating a perpendicular bisector, the entire space is divided into polyhedrons, or the entire plane is divided into polygons. The polyhedrons formed in this way are called Voronoi polyhedrons, and polygons are called Voronoi polygons. And the division of the plane is called Voronoi division.
[0161]
FIG. 2 shows an example of toner particles according to the present invention divided by Voronoi polygons (Voronoi polyhedrons).
[0162]
That is, in the present invention, focusing on the center of gravity of the islands present in the toner particles, polygons are formed by vertical bisectors formed by connecting the centers of gravity of adjacent islands, and the areas of these polygons are transmitted through the transmission area. Calculation is performed by an image analysis apparatus installed in the electron microscope apparatus based on a photograph taken by a scanning electron microscope.
[0163]
Here, the large area of the Voronoi polygon means that the distance between the centroids of adjacent islands is separated, that is, the sparse state of the occupied state of the island part in the particle It shows the thing. A small Voronoi polygon has a short distance between the centroids of adjacent islands, that is, the islands in the particles are densely occupied.
[0164]
In the present invention, about the Voronoi polygon of the island part in a toner particle, it measured about 1000 toners, and calculated the average value of the area of a Voronoi polygon.
[0165]
In addition, when the Voronoi polygon is generally defined mathematically, it is defined by the following formula.
[0166]
《Voronoi Polygon Area》
The set of Voronoi polygons V (i) for N independent points P (i) (1 ≦ i ≦ N) in the two-dimensional space R2 or the three-dimensional space R3 is
V (i) = {X || X · P (i) | <| X · P (j) |
for all i to j}
In the equation, X and P are position vectors, and || represents a distance in Euclidean space.
[0167]
V (i) defined in this way is assumed to form a Voronoi polygon in R2 and a Voronoi polyhedron in R3, and when V (i) and V (j) are adjacent, the boundary of the Voronoi polygon is It is defined as a part of a perpendicular bisector of a line segment connecting P (i) and point P (j). The Euclidean space is as defined and described in the Mathematical Science Dictionary.
[0168]
Further, the center of gravity of the toner particles of the present invention and the center of gravity of each island in the toner particles are obtained by the moment of the image, and are automatically calculated by the image analysis apparatus installed in the transmission electron microscope apparatus. Here, the barycentric coordinates of the toner particles are obtained by multiplying the brightness value of a minute area at an arbitrary point of the toner particles by the coordinate value of the arbitrary point. Then, the product of the brightness and the coordinate value is obtained for all coordinates existing in the entire toner particles, and the sum of the products is the brightness of the toner particles (the sum of the brightness values at the respective coordinate points obtained as described above). It is required by dividing. Similarly, for the center of gravity of the island, the center of gravity of the island is also calculated by obtaining the luminance at an arbitrary coordinate point in the island. As described above, the center-of-gravity coordinates of the toner particles of the present invention and the center-of-gravity coordinates of each island present in the toner particles are calculated based on the luminance at each arbitrary point, that is, from the brightness of the image.
[0169]
In the present invention, the average value of the area of the Voronoi polygon formed by the perpendicular bisector between the centroids of adjacent islands in the toner particles is 20,000 to 120,000 nm.²And the coefficient of variation of the average value of the area is 25% or less. In the present invention, the coefficient of variation of the area of the Voronoi polygon is calculated by the following equation.
[0170]
The coefficient of variation of the area of the Voronoi polygon = {S4 / K4} × 100 (%)
In the formula, S4 represents the standard deviation of the area of the Voronoi polygon in the island portion present in the toner particles, and K4 represents the average value of the area of the Voronoi polygon.
[0171]
Further, the average value of Voronoi polygons of adjacent islands in the toner particles according to the present invention is more preferably 40,000 to 100,000 nm.²And the coefficient of variation is 20% or less.
[0172]
The average value of the area of the Voronoi polygon formed by the perpendicular bisector between the centroids of adjacent islands in the toner particles according to the present invention is in the range of 20,000 to 120,000 nm2. If the value is out of this range, the occupancy of the islands in the toner particles becomes unfavorable. For example, the colorant present as an island in the particles is not effectively added to the toner particles. Thus, it is difficult to find the effect of the present invention, which is not preferable.
[0173]
The variation coefficient of the average value of the area of the Voronoi polygon formed from the adjacent islands in the toner particles according to the present invention is to specify the variation in the area of the Voronoi polygon, that is, the island portion in the toner particles The variation of the occupation state is specified, and the coefficient of variation of the average value of the area of the Voronoi polygon may be 25% or less, and preferably 20% or less. When the coefficient of variation is 0%, that is, in a state where there is no variation in the average value of the Voronoi polygon area, in other words, in a state where there is no variation in the occupied state of the islands in the toner particles, all the toner particles There is no need for the occupancy to be the same.
[0174]
In the present invention, the area of the Voronoi polygon formed by the islands existing within the specific range from the center of gravity of the toner particles is smaller than the area of the Voronoi polygon formed by the islands existing outside the range. It is characterized by being. That is, in the present invention, the average value of the areas of Voronoi polygons formed by islands existing within a radius of 1000 nm from the gravity center of the toner particles is the average value of the areas of Voronoi polygons formed by islands existing within a radius of 1000 nm. This means that in the toner particles, the dispersed state of the islands is sparse at some distance from the center of gravity of the toner particles. By satisfying this condition, in the toner of the present invention, the effect achieved by the present invention can be found by dispersing the islands in the toner particles appropriately.
[0175]
In the present invention, the area of the Voronoi polygon is 160,000 nm.²It is preferable that the number of islands as described above is 5 to 30 in one toner particle, which means that the islands are moderately dispersed. By having the distance, the islands are not unevenly distributed in the toner particles, and the colorant is effectively added to the toner particles.
[0176]
In the toner of the present invention, toner particles having a sea-island structure are preferable, and toner particles having a region where no island is present in the region along the outer periphery of the toner particle are preferably used. The toner particles having the sea island structure as described above will be specifically described with reference to the schematic cross-sectional view of the toner particles shown in FIG.
[0177]
In the schematic cross-sectional view of FIG. 3, the region indicated by the length a and the depth b along the outer periphery of the toner particle cross-section is a region not including an island.
[0178]
In the toner particle according to the present invention, a toner particle having a region which does not include an island part having a depth of 100 to 200 nm and a length of 500 to 6000 nm in the region along the outer periphery of the toner particle cross section is preferably used.
[0179]
In this way, by not allowing islands to exist in specific areas along the outer periphery of the toner particles, it is possible to effectively prevent the islands from spilling from the toner particles, and further, crystalline substances added to the toner particles and coloring It is presumed that the agent can be appropriately dispersed in the particles and the crystalline substance can be effectively leached during pressure fixing.
[0180]
The toner particles according to the present invention preferably have a sea-island structure from the result of observation with a transmission electron microscope, but the crystalline substance added to the toner particles (for example, the release agent described above) is crystalline. Island of substance is formed, and the colorant is formed of island of colorant. Thus, it is preferable that a plurality of types of islands are formed for each kind of additive. The characteristics described so far are those of the same type, that is, between the islands of the crystalline material or between the islands of the colorant and not between different islands.
[0181]
The islands with different additives, that is, the islands of the crystalline material and the islands of the colorant are different in brightness, so that they can be easily identified in the electron micrograph, and the image analysis device for calculating the above-mentioned characteristics is erroneous. It is set so that the characteristic value between different islands is not calculated. Regarding the islands in the toner particles of the present invention, the islands of the crystalline substance are specified by the ferret diameter, the shape factor of the islands, the number of islands present per toner particle, and the islands of the colorant are , Specified by the area of the Voronoi polygon.
[0182]
A method for producing the toner for developing an electrostatic charge image of the present invention will be described.
The toner of the present invention forms resin particles in the absence of a colorant, adds a dispersion of colorant particles to the dispersion of the resin particles, and saltes out, agglomerates, and melts the resin particles and the colorant particles. It is prepared by making it wear.
[0183]
Thus, the polymerization reaction for obtaining the composite resin particles is not inhibited by preparing the resin particles in a system in which no colorant is present. Therefore, according to the toner of the present invention, the excellent offset resistance is not impaired, and the fixing device is not contaminated or the image is not stained due to the accumulation of toner.
[0184]
In addition, as a result of the polymerization reaction for obtaining the resin particles being reliably performed, no monomer or oligomer remains in the obtained toner particles, and in the heat fixing step of the image forming method using the toner. Does not cause off-flavors.
[0185]
Furthermore, since the surface characteristics of the obtained toner particles are uniform and the charge amount distribution is sharp, an image with excellent sharpness can be formed over a long period of time.
[0186]
The resin particles constituting the toner of the present invention have one or more coating layers made of a resin having a different molecular weight and / or composition from the resin forming the core particles so as to cover the surface of the core particles made of the resin. The formed resin particles having a multilayer structure are preferable.
[0187]
That is, the molecular weight distribution of the resin particles is not monodispersed, and the resin particles usually preferably have a molecular weight gradient from the center (core) to the outer layer (shell).
[0188]
In the present invention, it is preferable to use a “multistage polymerization method” in order to obtain resin particles from the viewpoint of molecular weight distribution control, that is, from the viewpoint of securing fixing strength and offset resistance. In the present invention, the “multi-stage polymerization method” for obtaining resin particles refers to a monomer in the presence of resin particles (n) obtained by polymerizing the monomer (n) (n-th stage). (N + 1) is polymerized (stage n + 1), and the surface of the resin particles (n) has a polymer of monomer (n + 1) (the constituent resin of the resin particles (n) is dispersed and / or of composition. A method for forming a coating layer (n + 1) made of a different resin will be described.
[0189]
Here, when the resin particle (n) is a core particle (n = 1), it becomes “two-stage polymerization method”, and when the resin particle (n) is a composite resin particle (n ≧ 2), It becomes a multistage polymerization method of three or more stages.
[0190]
A plurality of resins having different compositions and / or molecular weights are present in the composite resin particles obtained by the multistage polymerization method. Therefore, the toner obtained by salting out, aggregating, and fusing the composite resin particles and the colorant particles has extremely small variations in composition, molecular weight, and surface characteristics among the toner particles.
[0191]
According to such a toner having a uniform composition, molecular weight, and surface characteristics between toner particles, an image forming method including a fixing process using a contact heating method maintains good adhesion (high fixing strength) to an image support. However, it is possible to improve the anti-offset property and the anti-winding property, and an image having an appropriate gloss can be obtained.
[0192]
An example of the method for producing the toner for developing an electrostatic charge image of the present invention is specifically shown as follows:
(1) Polymerization step for obtaining resin particles
(2) Step (II) of salting out, aggregating and fusing resin particles and colorant particles to obtain toner particles by salting out, agglomerating and fusing
(3) A filtration and washing process for separating the toner particles from the dispersion system of the toner particles and removing the surfactant from the toner particles.
(4) a drying step of drying the washed toner particles;
(5) A step of adding an external additive to the dried toner particles.
[0193]
Hereinafter, each step will be described.
As a method for incorporating the release agent into the resin particles (core particles), the release agent is dissolved in the monomer, the resulting monomer solution is dispersed in oil droplets in an aqueous medium, and this system is polymerized. Thus, a method of obtaining as latex particles can be employed.
[0194]
<< Step of salting out, agglomerating and fusing (II) >>
In the salting out, agglomerating and fusing step (II), the resin particles obtained in the polymerization step (I) and the colorant particles are salted out, agglomerated and fused (salting out and fusing at the same time). This is a step of obtaining non-spherical toner particles.
[0195]
In the salting out, agglomerating and fusing step (II), the composite resin particles and the colorant particles are used together with a release agent such as ester wax and an internal additive particle such as a charge control agent (number average primary particle size is 10). ˜1000 nm fine particles) may be added for salting out, agglomeration and fusion.
[0196]
The colorant particles may be surface modified. Here, as the surface modifier, a conventionally known one can be used.
[0197]
The colorant particles are subjected to salting out, aggregation, and fusion treatment in a state of being dispersed in an aqueous medium. Examples of the aqueous medium in which the colorant particles are dispersed include an aqueous solution in which the surfactant is dissolved at a concentration equal to or higher than the critical micelle concentration (CMC).
[0198]
As the surfactant, the same surfactant as that used in the multistage polymerization step (I) can be used.
[0199]
The disperser used for the dispersion treatment of the colorant particles is not particularly limited, but preferably, a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) equipped with a rotor rotating at high speed, an ultrasonic disperser. And a pressure disperser such as a mechanical homogenizer, a manton gourin and a pressure homogenizer, and a medium disperser such as a Getzmann mill and a diamond fine mill.
[0200]
In order to salt out, agglomerate, and fuse the resin particles and the colorant particles, a coagulant having a critical aggregation concentration or more is added to the dispersion in which the resin particles and the colorant particles are dispersed, and the dispersion is performed. It is preferable to heat the liquid to a temperature higher than the glass transition temperature (Tg) of the resin particles.
[0201]
More preferably, a coagulation terminator is used when the composite resin particles reach a desired particle size by the coagulant. As the aggregation terminator, a monovalent metal salt, particularly sodium chloride is preferably used.
[0202]
A temperature range suitable for salting out, agglomerating, and fusing is (Tg + 10) to (Tg + 50 ° C.), particularly preferably (Tg + 15) to (Tg + 40 ° C.). In addition, an organic solvent that is infinitely soluble in water may be added in order to effectively perform fusion.
[0203]
Examples of the “flocculating agent” used for salting out, agglomerating, and fusing include alkali metal salts and alkaline earth metal salts as described above.
[0204]
The salting out and aggregation according to the present invention will be described.
In the present invention, “salting out, agglomeration, fusion” means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur simultaneously, or salting out and fusion occur simultaneously. The act of letting go.
[0205]
In order to perform salting-out and fusion at the same time, it is preferable to agglomerate particles (composite resin particles, colorant particles) under a temperature condition higher than the glass transition temperature (Tg) of the resin constituting the composite resin particles. .
[0206]
The electrostatic image developing toner of the present invention forms resin particles in the absence of a colorant, and adds a dispersion of colorant particles to the dispersion of the composite resin particles, or a release agent dispersion as necessary. The resin particles are preferably prepared by salting out, aggregating and fusing the resin particles with the colorant particles, the release agent and the charge control agent.
[0207]
Thus, the polymerization reaction for obtaining the composite resin particles is not inhibited by preparing the resin particles in a system in which no colorant is present. Therefore, according to the toner of the present invention, the excellent offset resistance is not impaired, and the fixing device is not contaminated or the image is not stained due to the accumulation of toner.
[0208]
In addition, as a result of the polymerization reaction for obtaining the composite resin particles being reliably performed, no monomer or oligomer remains in the obtained toner particles, and the heat fixing step of the image forming method using the toner In this case, no off-flavor is generated.
[0209]
Furthermore, since the surface characteristics of the obtained toner particles are uniform and the charge amount distribution is sharp, an image with excellent sharpness can be formed over a long period of time. According to such a toner having a uniform composition, molecular weight, and surface characteristics between toner particles, good adhesion (high fixing strength) to an image support is maintained in an image forming method including a fixing process by a contact heating method. However, the offset resistance can be improved, and an image having an appropriate gloss can be obtained.
[0210]
Examples of the resin used for forming the resin particles described above include thermoplastic binder resins, and specifically, homopolymers or copolymers of styrenes such as styrene, parachlorostyrene, and α-methylstyrene. Polymer (styrene resin); methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-methacrylic acid n- Homopolymers or copolymers of vinyl groups such as propyl, lauryl methacrylate and 2-ethylhexyl methacrylate (vinyl resins); homopolymers or copolymers of vinylnitriles such as acrylonitrile and methacrylonitrile Combined (vinyl resin); vinyl methyl ether, vinyl isobut Homopolymers or copolymers of vinyl ethers such as ruether (vinyl resins); Homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone (vinyl resins); ethylene , Homopolymers or copolymers of olefins such as propylene, butadiene and isoprene (olefin resins); non-vinyl condensation resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, And graft polymers of these non-vinyl condensation resins and vinyl monomers. These resins may be used alone or in combination of two or more.
[0211]
Among these resins, vinyl resins are particularly preferable. The vinyl resin is advantageous in that the resin particle dispersion can be easily prepared by emulsion polymerization or seed polymerization using an ionic surfactant or the like. Examples of the vinyl monomer include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethylene imine, vinyl pyridine, vinyl amine, and other vinyl polymer acids and vinyl polymer bases. The monomer used as a raw material is mentioned. In the present invention, the resin particles preferably contain the vinyl monomer as a monomer component. In the present invention, among these vinyl monomers, vinyl polymer acids are more preferable from the viewpoint of ease of formation reaction of vinyl resins, and specifically, acrylic acid, methacrylic acid, maleic acid, cinnamon. A dissociable vinyl monomer having a carboxyl group such as acid or fumaric acid as a dissociating group is particularly preferred in terms of controlling the degree of polymerization and the glass transition point.
[0212]
The concentration of the dissociating group in the dissociable vinyl monomer is determined by dissolving particles such as toner particles from the surface, as described in, for example, polymer latex chemistry (Polymer Publications). Etc. can be determined. In addition, the molecular weight of the resin and the glass transition point from the surface of the particle to the inside can also be determined by the above method or the like.
[0213]
The number average particle diameter of the resin particles is usually at most 1 μm (1 μm or less), preferably 0.01 to 1 μm. When the number average particle diameter exceeds 1 μm, the particle diameter distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the number average particle diameter is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toner is improved, and the variation in performance and reliability is advantageous. . The number average particle diameter can be measured using, for example, a Coulter counter.
[0214]
The colorant dispersion is formed by dispersing at least a colorant. Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant carmine 6B. , DuPont oil red, pyrazolone red, risor red, rhodamine B rake, lake red C, rose bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate Pigment: Acridine, xanthene, azo, benzoquinone, azine, anthraquinone, dioxa , Thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, xanthene, and the like. . These colorants may be used alone or in combination of two or more.
[0215]
The number average particle size of the colorant is usually at most 1 μm (that is, 1 μm or less), preferably at most 0.5 μm (that is, 0.5 μm or less), particularly preferably 0.01 to 0.5 μm. When the number average particle diameter exceeds 1 μm, the particle diameter distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the number average particle diameter is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toner is good, and the variation in performance and reliability is advantageous. . Further, when the number average particle diameter is 0.5 μm or less, the obtained toner particles are advantageous in that they are excellent in color developability, color reproducibility, OHP permeability and the like. The number average particle diameter can be measured using, for example, a microtrack.
[0216]
Examples of the charge control agent used in the present invention include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments. In addition, as the charge control agent in the present invention, a material that is difficult to dissolve in water is preferable in terms of controlling ionic strength that affects stability during aggregation and fusion and reducing wastewater contamination.
[0217]
The developer used in the present invention will be described.
The toner of the present invention may be used as a one-component developer or a two-component developer.
[0218]
When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.
[0219]
Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a number average particle diameter of 15 to 100 μm, more preferably 25 to 80 μm.
[0220]
The number average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
[0221]
The image forming method according to the present invention will be described.
The image forming method according to the present invention refers to a toner image formed by developing an electrostatic latent image formed by charging and image exposure on a photoreceptor with a developer containing toner for developing an electrostatic latent image. This is an image forming method in which a large number of images are formed by repeating the steps of transferring to a transfer material using a contact transfer method and then separating, fixing and cleaning.
[0222]
FIG. 4 is a schematic configuration diagram illustrating an example of an image forming apparatus using a transfer roll.
In FIG. 4, a photoconductor 10 is an organic photoconductor that rotates in the direction of an arrow, 11 is a charger that applies uniform charge to the photoconductor, and the charger is a corona discharge device, a roller charger, a magnetic device. A brush charger may be used. Reference numeral 12 denotes digital image exposure light using an analog image exposure or a semiconductor laser, a light emitting diode or the like, and an electrostatic latent image is formed on the photosensitive member by the image exposure light. This electrostatic latent image is developed in contact or non-contact by a developer 13 containing a developer containing fine particle toner having a number average particle diameter of 2 to 10 μm, and a toner image is formed on the photoreceptor.
[0223]
The toner image is transferred onto the transfer material P conveyed in time with a DC bias applied by the transfer roll 15 at a pressing force of 2.5 to 100 kPa, preferably 10 to 80 kPa, to the photosensitive member.
[0224]
The DC bias power source 16 for applying a bias to the transfer roll 15 is preferably a constant current power source or a constant voltage power source. The constant current power source is 5 to 15 μA, and the constant voltage power source is 400 in absolute value. ~ 1500V.
[0225]
The transfer material P onto which the image has been transferred by the transfer roll 15 is separated from the photoreceptor 10 by the separation electrode 14, conveyed to a fixing device (not shown), and fixed by heating.
[0226]
The surface of the photoconductor after the transfer is cleaned by a cleaning blade 17 and then discharged by a charge removal lamp (PCL) 18 to prepare for the next image formation. Reference numeral 19 denotes a paper feed roller, and 20 denotes a fixing device.
[0227]
(Intermediate transfer member)
Transfer of the toner image from the photosensitive member to the transfer material can also be performed by a method using an intermediate transfer member. That is, an image forming unit (image forming unit) is provided for each of the four color developers, and a visible image for each color is formed on each photoconductor in each image forming unit, and these visible images are sequentially applied to the intermediate transfer member. It can also be preferably used in a system in which a color image is transferred and fixed onto a transfer material (usually plain paper, but is not particularly limited as long as it can be transferred) and then fixed.
[0228]
An image forming method in which images of a plurality of colors are formed in an image forming unit and transferred in sequence on the same intermediate transfer member will be described with reference to the drawings.
[0229]
FIG. 5 is a schematic configuration diagram illustrating an example of an image forming apparatus using an intermediate transfer member (transfer belt).
[0230]
In FIG. 5, in order to obtain a color image, the image forming apparatus includes a plurality of image forming units, each image forming unit forms a visible image (toner image) having a different color, and the toner images are the same. This is an image forming method in which the images are sequentially transferred onto an intermediate transfer member.
[0231]
Here, the first, second, third, and fourth image forming units Pa, Pb, Pc, and Pd are arranged in parallel, and the image forming portions are photosensitive members 1a that are electrostatic latent image forming members, respectively. 1b, 1c and 1d.
[0232]
The photoreceptors 1a, 1b, 1c and 1d have latent image forming portions 2a, 2b, 2c and 2d, developing portions 3a, 3b, 3c and 3d, transfer discharge portions 4a, 4b, 4c and 4d, cleaning members and Cleaning devices 5a, 5b, 5c and 5d having rubber blades and charging devices 6a, 6b, 6c and 6d are arranged.
[0233]
With such a configuration, first, a latent image of, for example, a yellow component color in a document image is formed on the photoreceptor 1a of the first image forming unit Pa by the latent image forming unit 2a. The latent image is converted into a visible image by a developer containing yellow toner in the developing unit 3a, and transferred to the transfer belt 21 by the transfer / discharge unit 4a.
[0234]
On the other hand, while the yellow toner image is transferred to the transfer belt 21 as described above, the second image forming unit Pb forms a magenta component color latent image on the photosensitive member 1b, and then the developing unit 3b generates magenta. A visible image is formed with a developer containing toner. This visible image (magenta toner image) is transferred to a predetermined position of the transfer belt 21 when the transfer belt that has been transferred by the first image forming unit Pa is carried into the transfer discharge section 4b. The
[0235]
Thereafter, cyan and black component images are formed by the third and fourth image forming units Pc and Pd in the same manner as described above, and a cyan toner image and a black toner image are formed on the same transfer belt. Are transferred in layers. When such an image forming process is completed, a multicolor superimposed image is obtained on the transfer belt 21. On the other hand, the photoreceptors 1a, 1b, 1c, and 1d after the transfer are removed from the residual toner by the cleaning devices 5a, 5b, 5c, and 5d, and are used for the subsequent latent image formation.
[0236]
In the image forming apparatus, a transfer belt 21 is used. In FIG. 5, the transfer belt 21 is conveyed from the right side to the left side, and in the conveyance process, each image forming unit Pa, Pb, Pc, and Each color transfer image is transferred through the transfer discharge portions 4a, 4b, 4c and 4d in Pd.
[0237]
When the transfer belt 21 passes through the fourth image forming unit Pd, the AC voltage is applied to the separation / discharge discharger 22d, the transfer belt 21 is discharged, and the toner images are transferred onto the transfer material P all at once. Thereafter, the transfer material P enters the fixing device 23, is fixed, and is discharged from the discharge port 25.
[0238]
In the figure, reference numerals 22a, 22b, 22c and 22d denote separate static elimination dischargers.
The transfer belt 21 that has finished transferring the toner image is cleaned of residual toner by a cleaning device 24 using both a brush-like cleaning member and a rubber blade, and is ready for the next image formation.
[0239]
In addition, as described above, a multi-color superimposed image is formed on a long transfer belt 21 such as a conveyor belt, and the image is transferred to a transfer material in a batch. An independent transfer belt may be provided, and then transferred from each transfer belt to a transfer material sequentially.
[0240]
The transfer belt has a surface resistance of 10 such as polyimide, polyether, polyamide or tetrafluoroethylene / perfluorovinyl ether copolymer.¹⁴On a high resistance film of Ω or more and a thickness of about 20 μm, a conductive agent is added to a fluorine-based or silicon-based resin to reduce the surface resistance to 10^Five-10⁸An endless film provided with a 5 to 15 μm-thick release layer that is Ω is used.
[0241]
As a suitable fixing method used in the present invention, a so-called contact heating method will be described with reference to FIGS.
[0242]
6A and 6B are schematic cross-sectional views each showing one embodiment of the fixing device used in the present invention.
[0243]
In the present invention, in particular, as a contact heating method, a heat pressure fixing method, a heat roll fixing method, and a pressure heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body can be given. it can.
[0244]
In the hot roll fixing method, in many cases, an upper roller having a heat source inside a metal cylinder composed of iron, aluminum or the like whose surface is coated with tetrafluoroethylene or polytetrafluoroethylene-perfluoroalkoxy vinyl ether copolymers, etc. And a lower roller made of silicone rubber or the like. A typical example of the heat source is one having a linear heater and heating the surface temperature of the upper roller to about 120 to 200 ° C. In the fixing unit, pressure is applied between the upper roller and the lower roller, and the lower roller is deformed to form a so-called nip. The nip width is 1 to 10 mm, preferably 1.5 to 7 mm. The fixing linear velocity is preferably 40 mm / sec to 600 mm / sec.
[0245]
A fixing cleaning mechanism may be provided for use. As this method, a method of supplying silicone oil to the upper roller or film for fixing, or a method of cleaning with a pad, roller, web or the like impregnated with silicone oil can be used.
[0246]
Next, a method for fixing by a rotating pressure member including a fixedly arranged heating body used in the present invention will be described.
[0247]
This fixing method is a method in which pressure fixing is carried out by a fixedly arranged heating body and a pressure member that is opposed to the heating body and presses the transfer material in close contact with the heating body through a film.
[0248]
In this press-contact fixing device, the heating body has a smaller heat capacity than a conventional heating roller, and has a line-shaped heating portion in a direction perpendicular to the passing direction of the transfer material. 300 ° C.
[0249]
The pressure contact fixing is a method of fixing an unfixed toner image against a heating source, such as a method in which a transfer material with unfixed toner is passed between a heating member and a pressure member as is usually used. is there. In this way, since heating is performed quickly, the fixing speed can be increased. However, temperature control is difficult, and the toner remains attached to a portion directly pressed against unfixed toner such as a surface portion of the heating source. There are also problems that toner offset is likely to occur, and that the transfer material is likely to fail such as winding around the fixing device.
[0250]
In this fixing method, the low-heat capacity line-shaped heating element fixedly supported by the apparatus has a thickness of 0.2 to 5.0 mm, more preferably 0.5 to 3.5 mm, a width of 10 to 15 mm, and a longitudinal length. A 240-400 mm alumina substrate is coated with a resistance material at 1.0-2.5 mm and is energized from both ends.
[0251]
The energization is a pulse waveform with a period of 15 to 25 msec with a DC of 100 V, and is changed to a pulse width corresponding to the temperature / energy release amount controlled by the temperature sensor. In the low heat capacity line-shaped heating element, when the temperature T1 is detected by the temperature sensor, the surface temperature T2 of the film facing the resistance material is lower than T1. Here, T1 is preferably 120 to 220 ° C, and the temperature of T2 is preferably 0.5 to 10 ° C lower than the temperature of T1. Further, the film material surface temperature T3 at the portion where the film peels from the toner surface is substantially equal to T2. The film moves in the direction of the center arrow in FIG. 6 (a) in contact with the heating body whose energy and temperature are controlled in this way. These fixing films are made by adding a conductive material to a heat-resistant film having a thickness of 10 to 35 μm, for example, polyester, polyperfluoroalkoxy vinyl ether, polyimide, polyetherimide, and in many cases a fluororesin such as Teflon. It is an endless film in which a release agent layer is coated by 5 to 15 μm.
[0252]
For driving the film, a driving force and tension are applied by a driving roller and a driven roller, and the film is transported in the direction of the arrow without wrinkles or twists. The linear velocity as the fixing device is preferably 40 to 600 mm / sec.
[0253]
The pressure roller has a rubber elastic layer having high releasability, such as silicone rubber, and is pressure-bonded to a heating body via a film material, and is pressed and rotated.
[0254]
Moreover, although the example using an endless film was demonstrated above, as shown in FIG.6 (b), you may use a film material with an end using the sending axis | shaft and winding axis | shaft of a film sheet. Furthermore, it may be a simple cylinder having no driving roller or the like inside.
[0255]
The fixing device may be used with a cleaning mechanism. As a cleaning method, a method of supplying various silicone oils to the fixing film, or a method of cleaning with a pad, roller, web or the like impregnated with various silicone oils is used.
[0256]
As the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, or the like can be used. Furthermore, siloxane containing fluorine can also be suitably used.
[0257]
Next, FIG. 6 shows an example of a sectional view of the fixing device.
In FIG. 6A, reference numeral 84 denotes a low heat capacity line-shaped heating element fixedly supported by the apparatus. As an example, a resistance material 86 is applied to an alumina substrate 85 having a height of 1.0 mm, a width of 10 mm, and a longitudinal length of 240 mm. Is applied to a width of 1.0 mm and is energized from both ends in the longitudinal direction.
[0258]
The energization is, for example, DC100V and is usually a pulse waveform with a cycle of 20 msec, and is controlled by a signal from the temperature measuring element 87 and kept at a predetermined temperature. For this reason, the pulse width is changed according to the amount of energy released, and the range is, for example, 0.5 to 5 msec.
[0259]
The transfer material 94 carrying the unfixed toner image 93 is brought into contact via the film 88 moving to the heating body 84 controlled in this way, and the toner is thermally fixed.
[0260]
The film 88 used here moves without wrinkles while being tensioned by the driving roller 89 and the driven roller 90. Reference numeral 95 denotes a pressure roller having a rubber elastic layer formed of silicone rubber or the like, and pressurizes the heating body through a film with a total pressure of 0.4 to 2.0 N. The unfixed toner image 93 on the transfer material 94 is guided to the fixing unit by the entrance guide 96, and a fixed image is obtained by heating.
[0261]
The endless belt has been described above. However, as shown in FIG. 6B, the film sheet feeding shaft 91 and the take-up shaft 92 are used, and the fixing film may be ended.
[0262]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[0263]
Example 1
<Preparation of latex>
(Preparation of latex 1HML)
(1) Preparation of core particles (first stage polymerization): (Preparation of latex 1H)
The following anionic surfactant (101) was added to a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet.
(101) C_TenH_{twenty one}(OCH₂CH₂)₂OSO_ThreeNa
A surfactant solution (aqueous medium) in which 7.08 g was dissolved in 3010 g of ion-exchanged water was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.
[0264]
To this surfactant solution, an initiator solution prepared by dissolving 9.2 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water was added, the temperature was adjusted to 75 ° C., and then 70.1 g of styrene, n -A monomer mixture consisting of 19.9 g of butyl acrylate and 10.9 g of methacrylic acid was added dropwise over 1 hour, and this system was polymerized by heating and stirring at 75 ° C for 2 hours (first stage polymerization). And a latex (a dispersion of resin particles made of a high molecular weight resin) was prepared. This is referred to as “latex (1H)”.
[0265]
(2) Formation of intermediate layer (second stage polymerization): (Preparation of latex 1HM)
In a flask equipped with a stirrer, 105.6 g of styrene, 30.0 g of n-butyl acrylate, 6.2 g of methacrylic acid, 5.6 g of n-octyl-3-mercaptopropionic acid ester, 98.0 g of an ester compound (carbon number 20 of fatty acid unit) represented by the above exemplified compound 20) was added, heated to 85 ° C. and dissolved to prepare a monomer solution.
[0266]
On the other hand, a surfactant solution in which 1.6 g of an anionic surfactant (101) was dissolved in 2700 ml of ion-exchanged water was heated to 95 ° C., and the latex (dispersed core particle) was added to the surfactant solution. 1H) is added in an amount of 28 g in terms of solid content, and then a monomer solution of Exemplified Compound 19) is prepared with a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. A dispersion (emulsion) containing emulsified particles (oil droplets) having a dispersed particle size (284 nm) was prepared by mixing and dispersing for a time.
[0267]
Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water and 750 ml of ion-exchanged water are added to this dispersion (emulsion), and the system is heated to 80 to 98 ° C. To polymerize by heating and stirring for 1 to 12 hours (second stage polymerization), latex (dispersion of composite resin particles having a structure in which the surface of resin particles made of high molecular weight resin is covered with intermediate molecular weight resin) Got. This is referred to as “latex (1HM)”.
[0268]
When the latex (1HM) was dried and observed with a scanning electron microscope, particles (400 to 1000 nm) containing, as a main component, the exemplified compound 19) that was not incorporated into the latex were observed.
[0269]
(3) Formation of outer layer (third stage polymerization): (Preparation of latex 1HML)
An initiator solution obtained by dissolving 7.4 g of a polymerization initiator (KPS) in 200 ml of ion-exchanged water is added to the latex (1HM) obtained as described above, and under a temperature condition of 80 ° C., 300 g of styrene, A monomer mixture composed of 95 g of n-butyl acrylate, 15.3 g of methacrylic acid, and 10.4 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and latex (a central portion made of a high molecular weight resin, an intermediate layer made of an intermediate molecular weight resin, A dispersion of composite resin particles) having an outer layer made of a molecular weight resin and containing the exemplified compound 19) in the intermediate layer was obtained. This latex is referred to as “latex (1HML)”.
[0270]
The composite resin particles constituting the latex (1HML) had peak molecular weights of 138,000, 80,000 and 13,000, and the number average particle diameter of the composite resin particles was 122 nm.
[0271]
(Preparation of latex 2HML)
Latex 2HML was obtained in the same manner as in the production of latex (1HML) except that Exemplified Compound 21) (with 18 carbon atoms in the fatty acid unit) was used instead of Exemplified Compound 20).
[0272]
The composite resin particles constituting the latex (2HML) had peak molecular weights of 146,000, 90,000 and 13,000, and the number average particle size of the composite resin particles was 126 nm.
[0273]
(Preparation of latex 3HML)
Latex 3HML was obtained in the same manner as in the production of latex (3HML) except that Exemplified Compound 18) (C28 of fatty acid unit) was used instead of Exemplified Compound 20).
[0274]
The composite resin particles constituting the latex (3HML) had peak molecular weights of 117,000, 90,000 and 12,000, and the number average particle diameter of the composite resin particles was 118 nm.
[0275]
<< Manufacture of colored particles 1 >>
Anionic surfactant (101) 59.0 g was stirred and dissolved in 1600 ml of ion-exchanged water. While stirring this solution, 420.0 g of C.I. I. Pigment Red 122 is gradually added, and then dispersion treatment is performed using “CLEARMIX” (manufactured by M Technique Co., Ltd.), whereby a dispersion of colorant particles (hereinafter referred to as “colorant dispersion 1”). Prepared). When the particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the weight average particle diameter was 89 nm.
[0276]
420.7 g of latex 1HML (converted to solid content), 900 g of ion-exchanged water, and 166 g of colorant dispersion 1 were placed in a reaction vessel (four-necked flask) equipped with a temperature sensor, a condenser, a nitrogen introducing device, and a stirring device. ) And stirred. After adjusting the internal temperature to 30 ° C., a 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8 to 10.0.
[0277]
Next, an aqueous solution in which 12.1 g of magnesium chloride hexahydrate was dissolved in 1000 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 6 to 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II”, and when the number average particle size became 4 to 7 μm, an aqueous solution in which 80.4 g of sodium chloride was dissolved in 1000 ml of ion-exchanged water. Was added to stop particle growth, and the fusion was continued by heating and stirring at a liquid temperature of 85 to 98 ° C. for 2 to 12 hours as an aging treatment. Then, it cooled to 30 degreeC, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced association particles were filtered, washed repeatedly with ion exchange water at 45 ° C., and then dried with hot air at 40 ° C. to obtain colored particles 1.
[0278]
Here, in the production of the colored particles 1, the pH of the agglomeration step, the temperature of the aging treatment step, the aging time, and the stirring strength are controlled to control the release agent, the colorant dispersion state, and the variation coefficient of the shape and shape factor. The particle size and the coefficient of variation of the particle size distribution were adjusted as shown in Table 1 by further classification.
[0279]
(Production of comparative colored particles 1 to 7)
In the production of the colored particles 1, the release agent, the colorant dispersion state, and the variation coefficient of the shape and the shape factor are controlled by controlling the pH of the aggregation process, the temperature of the aging process, the aging time, and the stirring intensity. Further, colored particles 1 to 7 for comparison were produced in the same manner except that the variation coefficient of particle size and particle size distribution was adjusted as shown in Table 1 by classification in liquid.
[0280]
(Production of colored particles 2 and 3)
In the production of colored particles 1, latex 2HML is used instead of latex 1HML, and C.I. I. Colored particles 2 having the characteristics shown in Table 1 were produced using Pigment Yellow 180 instead of Pigment Red 122.
[0281]
In the production of colored particles 1, latex 3HML is used instead of latex 1HML, and C.I. I. Colored particles 3 having the characteristics shown in Table 1 were produced using phthalocyanine pigment (manufactured by BASF, PB-FAST BLUE) instead of CI Pigment Red 122.
[0282]
[Table 1]

[0283]
<< Production of Electrostatic Image Developing Toner Particles 1 to 5 and Comparative Electrostatic Image Developing Toner Particles 1 to 13 of the Present Invention >>
In each of the colored particles 1 to 3 and the comparative colored particles 1 to 7 obtained as described above, 1.0 part by mass of hydrophobic acicular titanium (hydrophobized with normal butyltrimethoxysilane) shown in Table 2 And / or 0.8 parts by mass of silica (manufactured by deflagration method, hydrophobized with hexamethylsilazane), and the peripheral speed of the rotor blade of a 10 liter Henschel mixer is set to 30 m / s and mixed did. In addition, when adding both acicular titanium and silica particles produced by the deflagration method, after adding titanium particles and mixing for 10 minutes, silica particles produced by the deflagration method are added and further mixed for 15 minutes. The toner particles 1 to 5 for developing an electrostatic image of the present invention and the toner particles 1 to 13 for developing an electrostatic image for comparison were obtained. Here, in preparing each of the toner particles described above, as shown in Table 3, the BET specific surface area of the toner particles, the fatty acid carbon number of the ester wax, the alcohol carbon number, the average value of the area of the Voronoi polygon, and the fluctuation Coefficient, area of Voronoi polygon (160000 nm²Component (%)) was adjusted.
[0284]
Further, in the process of preparing each of the toner particles for developing an electrostatic charge image of the present invention and comparative from the colored particles, each colored particle that becomes the base of each toner particle described above is added by adding an external additive, etc. Its shape and particle size do not change.
[0285]
[Table 2]

[0286]
[Table 3]

[0287]
<Manufacture of carriers>
(Manufacture of ferrite core material)
18 mol% of MnO, 4 mol% of MgO, Fe₂O_Three78 mol% was pulverized, mixed and dried in a wet ball mill for 2 hours, and then temporarily calcined by holding at 900 ° C. for 2 hours, and this was pulverized in a ball mill for 3 hours to form a slurry. Dispersant and binder are added, granulated and dried by spray dryer, then fired at 1200 ° C. for 3 hours, resistance 4.3 × 10⁸Ω ferrite core material particles were obtained.
[0288]
(Manufacture of coating resin)
Cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) by an emulsion polymerization method in which the concentration in an aqueous medium using sodium benzenesulfonate having an alkyl group having 12 carbon atoms as a surfactant is 0.3% by mass. A volume average primary particle size of 0.1 μm, a mass average molecular weight (Mw) of 200,000, a number average molecular weight (Mn) of 91,000, Mw / Mn = 2.2, a softening point temperature (Tsp ) 230 ° C. and glass transition temperature (Tg) 110 ° C. Resin fine particles were obtained.
[0289]
The resin fine particles azeotroped with water in the emulsified state, and the residual monomer amount was 510 ppm. Next, 100 parts by mass of ferrite core material particles and 2 parts by mass of the resin fine particles are put into a high-speed agitator / mixer with agitating blades, and agitated and mixed at 120 ° C. for 30 minutes to use the action of mechanical impact force. Thus, a resin-coated carrier having a number average particle diameter of 61 μm was obtained.
[0290]
<Manufacture of developer>
Each of the electrostatic charge image developing toner particles 1 to 5 described above and the comparative electrostatic charge image developing toner particles 1 to 13 are mixed with the carrier described above, and as shown in Table 4, the electrostatic charge image developing toner particles are mixed. Developer samples 1 to 18 having a toner concentration of 6% by mass were prepared.
[0291]
《Developer evaluation method》
Each of the developer samples 1 to 18 obtained as described above is mounted on a digital copying machine having an image forming process as shown in FIG. 5 in a low temperature and low humidity environment (temperature 10 ° C., relative humidity 20 %) And in a high temperature and high humidity environment (temperature 33 ° C., relative humidity 80%), halftone uniformity, fine dot dust, and transfer rate were evaluated as shown below. Further, the filming of the transfer body was evaluated by performing a live-action test in which 100,000 images having a pixel rate of 65% were formed.
[0292]
In performing the evaluation described below, the setting conditions of the digital copying machine were adjusted as follows.
[0293]
(Charging conditions)
Charger; roller charger, initial charge potential of -750V
(Exposure conditions)
Set the exposure amount to -50V for the exposure area potential.
(Development condition J)
DC bias; -550V
The following “transfer belt” was used as the transfer belt. The “transfer belt” has a surface resistance of 7 × 10 by adding a conductive agent to a fluororesin on a polyimide film (surface resistance 1014Ω, high resistance film having a thickness of 20 μm).⁶An endless film provided with a release layer having a thickness of 10 μm and set to Ω.
[0294]
(Uniformity of halftone)
The uniformity of halftone images due to photoconductor filming and transferability variation was evaluated. The rank was evaluated as follows.
[0295]
Rank A: Uniform image without unevenness (good)
Rank B: One thin stripe-like unevenness exists (no problem in practical use)
Rank C: There are several thin stripes (unusable)
Rank D: Several or more streaky irregularities exist (defect)
(Chile of fine dots)
A 10% halftone dot image was formed on the entire surface of the image, and dust around the dots was observed with a magnifying glass.
[0296]
◎: Chile can hardly be detected
○: Slightly dusty but not noticeable without attention (practical)
×: Easy to detect dust (unusable)
(Evaluation of transfer rate)
The transfer rate (%) was determined by the following formula (1), and rank evaluation was performed as follows.
[0297]
Formula (1)
Transfer rate (%) = {1− (mass of collected toner / mass of consumed toner)} × 100
A: Transfer rate exceeds 99.5% (very good)
○: 99.0 to 99.5% (good)
Δ: 95.0 to less than 99.0% (unusable)
X: Less than 95.0% (defect)
(Evaluation of transfer filming)
The presence or absence of filming was determined by visual observation.
[0298]
Not generated: The transfer body is not cloudy and no filming is confirmed.
Generation: Filming can be confirmed on the transfer body
The obtained evaluation results are shown in Table 4.
[0299]
[Table 4]

[0300]
From Table 4, it is clear that the sample of the present invention has better halftone uniformity, no fine dot dust, and excellent characteristics such as transfer rate and transfer filming, as compared with the comparison. It is.
[0301]
【The invention's effect】
According to the present invention, it is possible to provide a toner for developing an electrostatic charge image having good halftone uniformity, no dust of fine dots, and excellent properties such as transfer rate and filming of a transfer member. .
[Brief description of the drawings]
FIGS. 1A and 1B are explanatory views showing projected images of toner particles having no corners, and FIGS. 1B and 1C are explanatory views showing projected images of toner particles having corners, respectively.
FIG. 2 is a schematic cross-sectional view of toner particles having a sea-island structure used in the present invention divided by Voronoi polygons.
FIG. 3 is a schematic cross-sectional view showing an example of toner particles having a sea-island structure used in the present invention.
FIG. 4 is a schematic sectional view showing an example of an image forming apparatus using a transfer roll.
FIG. 5 is a schematic cross-sectional view illustrating an example of an image forming apparatus using a transfer belt.
FIG. 6 is a structural cross-sectional view of a fixing device using a transfer belt.
[Explanation of symbols]
10 photoconductor
11 Charger
12 Image exposure light
13 Developer
14 Separation pole
15 Transfer roll
16 Bias power supply
17 Cleaning blade
18 Static elimination lamp
19 Paper feed roller
20 Fixing device
P transfer material
Pa, Pb, Pc, Pd Image forming unit
1a, 1b, 1c, 1d photoconductor
2a, 2b, 2c, 2d Latent image forming unit
3a, 3b, 3c, 3d Development section
4a, 4b, 4c, 4d Transfer discharge part
5a, 5b, 5c, 5d Cleaning device
6a, 6b, 6c, 6d charger
21 Transfer belt
22a, 22b, 22c, 22d Separate static elimination discharger
23 Fixing device
24 Cleaning device
25 outlet
84 Heating body
85 Alumina substrate
86 Resistance material
87 Thermometer
88 films
89 Driving roller
90 Followed roller
91 Feed axis
92 Winding shaft
93 Unfixed toner image
94 Transfer material
95 Pressure roller

Claims (16)

All toner particles including toner particles including a resin, a colorant, and an external additive, the toner particles having a number average particle diameter of 2 to 10 μm and a shape factor in the range of 1.2 to 1.6 In the toner for developing an electrostatic charge image, the proportion of the particles is 65% by number or more, the variation coefficient of the shape factor of the toner particles is 16% or less, and the number variation coefficient in the number particle size distribution is 27% or less.
The surface of the toner particles has a ratio of the length of the major axis to the length of the minor axis of 2 to 20, titanium oxide fine particles having a major axis length of 10 to 200 nm, or a circularity coefficient of 0.976 to 1. A toner for developing an electrostatic charge image, comprising hydrophobic metal oxide particles having a number average particle diameter of 1.000 and having a number average particle size of 35 to 140 nm.   2. The electrostatic image developing toner according to claim 1, wherein the hydrophobized metal oxide particles are silica particles.   The electrostatic charge image developing toner according to claim 1, wherein at least one of the external additives is metal oxide particles produced by a deflagration method.   4. The electrostatic image developing toner according to claim 3, wherein the metal oxide particles produced by the deflagration method are silica particles. The toner particles are prepared through a process of agglomerating and fusing resin particles in an aqueous medium, and the residual surfactant content in the toner particles is 1-1000 ppm, and the content of divalent or trivalent metal element is 250. 5. The static electricity according to claim 1, wherein the toner particle surface has titanium oxide fine particles having a surface treatment of 2 to 1800 ppm and a water-soluble component amount of 2 to 1800 ppm. Toner for charge image development.   6. The toner for developing an electrostatic charge image according to claim 1, wherein a ratio of the toner particles having no corners in the toner particles is 50% by number or more.   The toner for developing an electrostatic charge image according to claim 1, wherein the toner particles have a resin obtained by polymerizing a polymerizable monomer in an aqueous medium. The toner for developing an electrostatic image according to claim 1, wherein the toner particles have a BET specific surface area of 1.1 to 3.5 g / m ² . The cross-sectional photograph obtained by photographing the toner particles with a transmission electron microscope has an average area of Voronoi polygons at the center of gravity of a low-luminance island of 20000 to 120,000 nm ² and a coefficient of variation of 25% or less. The toner for developing an electrostatic charge image according to any one of 1 to 8. 2. A cross-sectional photograph obtained by photographing a toner particle with a transmission electron microscope, wherein an average value of Voronoi polygons at the center of gravity of a low-luminance island is 40,000 to 100,000 nm ² and a coefficient of variation is 20% or less. The toner for developing an electrostatic charge image according to any one of 1 to 9. In a cross-sectional photograph obtained by photographing the toner particles with a transmission electron microscope, the average value of the Voronoi polygon area at the center of gravity of the low-brightness island is 20000 to 120,000 nm ² and contains 3 to 20% of a component of 160000 nm ² or more. The toner for developing an electrostatic charge image according to any one of claims 1 to 10, wherein the toner is a toner for developing an electrostatic image.   12. The toner particle according to claim 1, wherein the toner particles contain a release agent, and the release agent contains an ester compound having a higher alcohol having 12 to 35 carbon atoms or a higher fatty acid having 12 to 35 carbon atoms. 2. The toner for developing an electrostatic charge image according to item 1. In producing the toner for developing an electrostatic charge image according to any one of claims 1 to 12, the ratio of the length of the major axis to the length of the minor axis is 2 to 20 on the surface of the toner particles. A step of externally fixing and fixing titanium oxide fine particles having a length of 10 to 200 nm,
An electrostatic charge having a roundness coefficient of 0.976 or more, a number average particle diameter of 35 to 140 nm, a step of externally fixing and fixing hydrophobized metal oxide particles manufactured by a deflagration method A method for producing a toner for image development.   14. The method for producing a toner for developing an electrostatic charge image according to claim 13, wherein the hydrophobized metal oxide particles are silica particles.   In producing the toner for developing an electrostatic charge image according to any one of claims 1 to 12, it is obtained by agglomerating and fusing resin particles in an aqueous medium, containing 1 to 1000 ppm of a residual surfactant, In addition, a fine particle of titanium oxide containing 2 to 1800 ppm of a water-soluble component as an external additive is fixed on the surface of colored particles containing 250 to 20000 ppm of a divalent or trivalent metal element. A method for producing a toner for developing an electrostatic image, comprising obtaining particles.   A toner image formed by developing an electrostatic latent image formed by charging and image exposure on an electrophotographic photosensitive member with a toner for developing an electrostatic image is transferred to a transfer material using a contact transfer method, and thereafter An image forming method in which each of the steps of separation, fixing, and cleaning is repeated, wherein the toner for developing an electrostatic charge image according to any one of claims 1 to 12 is used.

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