JP3979563B2 - Electrophotographic carrier and electrophotographic developer - Google Patents

Description

上記式中Ｒ₁は水素原子、炭素原子１〜４のアルキル基またはフェニル基、Ｒ₂およびＲ₃は水素基、炭素原子数１〜４のアルコキシ基、フェニル基、フェノキシ基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニルオキシ基、ヒドロキシ基、カルボキシル基、エチレンオキシド基、グリシジル基または下記式で示される基である。
【００３２】
【化２】

上記式中Ｒ₄、Ｒ₅はヒドロキシ基、カルボキシル基、炭素原子数１〜４のアルキル基、炭素原子数１〜４のアルコキシ基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニルオキシ基、フェニル基、フェノキシ基、ｋ、ｌ、ｍ、ｎ、ｏ、ｐは１以上の整数を示す。
【００３３】
上記各置換基は未置換のもののほか、例えばアミノ基、ヒドロキシ基、カルボキシル基、メルカプト基、アルキル基、フェニル基、エチレンオキサイド基、グリシジル基、ハロゲン原子のような置換基を有してもよい。
【００３４】
ポリシラザンとしては、従来から知られている置換基を含まないペルヒドロポリシラザンであってもよく、水素原子の一部をアルキル基、フェニル基、アルキルフェニル基、アルケニル基や、これらのハロゲン化物、スルホ基、ホスフィノ基、ホスフィニル基、ホスフィノチオイル基等により置換した部分置換ポリシラザンや、これらの複合重合物であっても良い。
【００３５】
また前述のようにキャリアコア材粒子及び／又はコート層の電気抵抗を低抵抗材料粒子の分散により制御する際に用いられる材料は、従来公知のもので良く、その例としては、鉄、金、銅等の金属；フェライト、マグネタイト等の酸化鉄；カーボンブラック等の顔料が挙げられる。
【００３６】
この中でも特にカーボンブラックの一つであるファーネスブラックとアセチレンブラックの混合物を用いることにより、少量の低抵抗微粉末の添加で効果的に導電性の調整が可能であり、好ましく用いられる。これらの低抵抗微粉末は、粒径０．０１〜１０μｍ程度のものが好ましく、コア材粒子またはコート層樹脂１００重量部に対して２〜３０重量部添加されることが好ましく、さらには５〜２０重量部が好ましい。
【００３７】
また、キャリアコア材粒子及び／又はコート層中には、これらの密着性を向上させたり抵抗制御材の分散性を向上させる目的でシランカップリング剤、チタンカップリング剤等のカップリング剤を助剤として添加しても良い。
【００３８】
本発明で用いられるシランカップリング剤の例としては、下記一般式で示される化合物が挙げられる。
【００３９】
【化３】

但し、Ｘ₃はけい素原子に結合している加水分解基でクロル基、アルコキシ基、アセトキシ基、アルキルアミノ基、プロペノキシ基などがある。
Ｙは有機マトリックスと反応する有機官能基でビニル基、メタクリル基、エポキシ基、グリシドキシ基、アミノ基、メルカプト基などがある。
Ｒは炭素数１〜２０のアルキル基またはアルキレン基である。
【００４０】
このシランカップリング剤の中でも、特に負帯電性を有する現像剤を得るにはＹにアミノ基を有するアミノシランカップリング剤が好ましく、正帯電性を有する現像剤を得るにはＹにエポキシ基を有するエポキシシランカップリング剤が好ましい。
本発明のキャリアを製造する方法としては、コア材粒子の表面にコート層形成液を噴霧法、浸漬法等の手段で塗布すればよい。
特に、樹脂組成物および溶媒を含むコート液を、少なくとも磁性体よりなるコア材を加熱しつつ塗工することにより、コート液中の溶媒を除去して樹脂成分をコア材表面に固定化し、更に塗工時の温度より高い温度に加熱してコート層を形成することが好ましい。
この様な製造方法をとることにより、コート液に含まれる樹脂組成物が均質に複合化した、本発明の構成に合致した構造を持つコート層組成物をコア材表面に形成することができる。
被覆層の厚さは０．１〜２０μｍが好ましい。
【００４１】
本発明は第２の構成として、最小の位相変移量Ｅｍｉｎを持つ成分Ａｍｉｎの占める面積をＳｍｉｎとしたとき、面積率Ｓｍｉｎ／ΣＳ(ｉ)×１００が８０％以下であることを特徴とする前記第１の構成に記載の電子写真用キャリアである。
【００４２】
該本発明の主旨であるところの、より安定した相互作用力バランスをとるためには、相互作用力の最も小さな領域の占有率が全表面の８０％以下であることが好ましく、これを越えるような場合には、相互作用力が最小の領域とトナー粒子が接触する確率が高くなりすぎるため、安定したトナー帯電量に至るまでの時間、いわゆるトナー帯電の立ち上がりが遅くなる場合がある。
【００４３】
一方、第３の構成を有する本発明は、最大の位相変移量Ｅｍａｘを持つ成分Ａｍａｘの占める面積をＳｍａｘとしたとき、面積率Ｓｍａｘ／ΣＳ（ｉ）×１００が６０％以下であることを特徴とする前記第１の構成に記載の電子写真用キャリアであり、前述の、第２の構成の本発明の場合と逆に、相互作用力の最も大きな領域の占有率が全表面の６０％を越えるような場合には、相互作用力が最大の領域とトナー粒子が接触する確率が高くなりすぎ、経時での安定性が十分に保てない場合がある。更には、Ａｍａｘの占める面積範囲が４５％以下であれば、より好ましい。
【００４４】
第４の構成の本発明は、Ｅｍｉｎ、Ｅｍａｘが、０．２≦Ｅｍｉｎ／Ｅｍａｘ≦０．７の関係式を満たすことを特徴とする前記第１の構成乃至第３の構成のいずれかに記載の電子写真用キャリアである。
ＥｍｉｎとＥｍａｘの値があまりにもかけ離れ、その比Ｅｍｉｎ／Ｅｍａｘが０．２を下回るような場合には、製造条件の僅かな差異により相互作用力トータル値が変動するため、安定して当該本発明主旨のキャリア粒子を得るためには好ましくない。逆にＥｍｉｎとＥｍａｘの値が近く、その比Ｅｍｉｎ／Ｅｍａｘが０．７を越えるような場合には、当該本発明の主旨とするところの複合構造が不明瞭となり、複合化による速やかなトナー粒子帯電と長寿命化の両立が、十分には発現しない場合がある。
【００４５】
また、トナー粒子とキャリア粒子表面との相互作用力の大きさはトナー粒子の種類や、二成分現像プロセスの構成に依存するため、一意的に表現することは困難であり、固有の値で特定されるものではない。したがって、Ｅｍｉｎ、Ｅｍａｘは、相対的な指標として、第４の本発明の構成の範囲０．２≦Ｅｍｉｎ／Ｅｍａｘ≦０．７であれば好ましく、０．２５〜０．５の範囲であれば更に好ましい。
【００４６】
第５の本発明の構成は、キャリア粒子表面の最大領域を占める成分Ａｍｏｄの領域面積をＳｍｏｄとしたとき、面積率Ｓｍｏｄ／ΣＳ(ｉ)×１００≦８０％であることを特徴とする前記第１の構成乃至第４の構成のいずれかに記載の電子写真用キャリアである。
【００４７】
上述までにもあるように、キャリア粒子の機能は、キャリア粒子表面における相互作用力の異なる領域の複合化及び複合状態によって制御される。したがって、同一の相互作用力を持つ領域の広さが、第５の構成の本発明の範囲を越え広い占有面積率をとるような場合には、他の領域の作用を十分に発現できないことがある。Ｓｍｏｄ／ΣＳ(ｉ)×１００は、６０以下であれば、更に好ましい。
【００４８】
第６の構成の本発明は、キャリア粒子表面の位相変移量分布を表わす表面画像内に、長さ２μｍに相当する任意の線分を重ねたとき、線分内を、Ａｍｏｄの占有する領域とＡｍｏｄ以外の占有する領域が少なくとも１カ所ずつ横切ることを特徴とする前記第１の構成乃至第５の構成のいずれかに記載の電子写真用キャリアである。
【００４９】
当該本発明のキャリア粒子の表面では、相互作用力の大きな領域と小さな領域が複合化されて存在しているが、各領域の複合状態、特にその内の最大面積を占める領域とその他の領域の複合状態によっては、各領域の作用が単独で発現してしまう場合がある。
【００５０】
したがって、当該本発明の効果を十分に発現させるには、各表面領域が高度に複合化しているほうが好ましく、具体的には第６の構成の本発明の範囲にある状態をとることが好ましい。表面の複合状態がこの構成を満たさないような場合は、Ａｍｏｄ領域またはＡｍｏｄ以外の領域の何れかが、長さ２μｍを越える領域に渡って独立に存在する。このような複合状態の部分では、実際にトナー粒子とキャリア粒子が撹拌された際に、両者の接触領域若しくはその近傍において、接触に関わらない成分領域が多数存在し得る。表面複合状態をこの構成を満たすようにすることにより、各領域が実質上十分に複合化されるため、キャリア粒子上の任意領域で、トナー粒子の略均一な接触・摩擦を行なうことができ、トナー粒子への電荷付与とキャリア粒子寿命の両立化のためには、より好ましいものである。
【００５１】
また同様に複合化の度合を示す別の指標として、Ａｍｏｄ領域とＡｍｏｄ以外の領域の境界線について好ましい状態を示すと、第７の構成の本発明は、Ａｍｏｄの占有する領域とＡｍｏｄ以外の占有する領域の境界線が、１．１〜１．６次元のフラクタル次元を持つことを特徴とする前記第１の構成乃至第６の構成のいずれかに記載の電子写真用キャリアである。
【００５２】
一般にフラクタル次元は、曲線等の複雑さを示す指標であり、この値を境界線に適用することにより、境界線がどの程度入り組んでいるかを示すことができ、これにより、複合化の程度を知ることができる。
【００５３】
境界線のフラクタル次元が、１．１を下回る場合には、各領域の十分な複合化が成されず、その結果各領域の相互作用力が個別に作用してしまい、相互作用力の比較的大きな領域でのトナー粒子成分固着等の抑制効果が長期に渡って持続できない場合がある。一方、フラクタル次元が１．６を越えるような場合では、複合の複雑さが大きすぎるため、単一相と略同一の挙動を示し易く、複合化による効果を発揮することが困難となりやすい。
【００５４】
Ａｍｏｄ領域とその他の領域の境界線における、フラクタル次元の求め方の例としては、概略以下のような方法が挙げられる。
まず、前述の方法により得た、ＳＰＭの位相変移量分布像の各領域面積から、Ａｍｏｄ領域を特定する。次に、画像処理によりＡｍｏｄ領域の境界線部分のみを抽出する。更に境界線の全長より短い同じ長さの直線線分を用いて境界線の長さを近似し、用いた線分の長さと要した線分の本数を求める。この両者の対数値をプロットしその勾配からフラクタル次元を読みとる。
【００５５】
また、フラクタル次元を求める他の方法としては、相関次元計算法によっても求めることができる。具体的には、まず、分布像Ａｍｏｄ領域の境界線部分のみを抽出し、境界線上の全ての点（総数＝Ｎ）において、各点を中心とした半径ｒの円内に入っている境界線上の点の数をカウントする。全ての点についてそのカウント数を総計し、更に総数Ｎの二乗で割った値をＣ（ｒ）とする。同様の操作を、円の半径ｒを変化させて行ない、点（ｌｏｇｒ、ｌｏｇＣ（ｒ））をプロットし、その勾配からフラクタル次元（相関次元）を読みとる。
【００５６】
比較的相互作用力の弱い領域の成分及び／又は最大占有面積をとる領域を容易に構成し、トナー粒子成分の固着を防止するには、これらの領域に、ケイ素原子を含有させることが好ましい。すなわち第８の構成の本発明は、Ａｍｉｎ及び／又はＡｍｏｄの占有する領域にケイ素原子を含むことを特徴とする前記第１の構成乃至第７の構成のいずれかに記載の電子写真用キャリアである。
【００５７】
一方、相互作用力が比較的強い領域の成分及び／又は最大占有面積をとる領域を構成し、トナー粒子への電荷付与を容易に行なうには、これらの領域に、窒素原子を含有させることが好ましい。すなわち第９の構成の本発明は、Ａｍａｘ及び／又はＡｍｏｄの占有する領域に窒素原子を含むことを特徴とする前記第１の構成乃至第８の構成のいずれかに記載の電子写真用キャリアである。
【００５８】
更に、第１０の構成の本発明は、キャリア粒子表面を占有する何れかの領域が、シロキサン結合を含むことを特徴とする前記第１の構成乃至第９の構成のいずれかに記載の電子写真用キャリアであり、第１１の構成の本発明は、キャリア粒子表面を占有する何れかの領域が、ポリシラザン骨格を有する構造を含むことを特徴とする前記第１の構成乃至第１０の構成のいずれかに記載の電子写真用キャリアである。本発明の複合化コート層表面は、特に、これらの構成をとることにより、更に見掛け上均一かつ、微視的には高度に複合化した高強度かつ靭性に富んだ表面とすることができる。
【００５９】
第１２の構成の本発明は、電子写真用キャリア粒子と、少なくとも結着樹脂及び着色剤を含むトナー粒子を混合してなる電子写真用現像剤において、該キャリア粒子が、前記第１の構成乃至第１１の構成のいずれかに記載の電子写真用キャリアであることを特徴とする電子写真用現像剤である。
【００６０】
本発明に使用するトナー粒子は、通常、電子写真用トナーとして使用されるものを、特に制限なく、使用することができる。
例えば、該電子写真用トナーに使用される結着剤樹脂の一例としては、ポリスチレン、ポリｐ−クロロスチレン、ポリビニルトルエン等のスチレン及びその置換体の単重合体；スチレン／ｐ−クロロスチレン共重合体、スチレン／プロピレン共重合体、スチレン／ビニルトルエン共重合体、スチレン／ビニルナフタレン共重合体、スチレン／アクリル酸メチル共重合体、スチレン／アクリル酸エチル共重合体、スチレン／アクリル酸ブチル共重合体、スチレン／アクリル酸オクチル共重合体、スチレン／メタクリル酸メチル共重合体、スチレン／メタクリル酸エチル共重合体、スチレン／メタクリル酸ブチル共重合体、スチレン／α−クロルメタクリル酸メチル共重合体、スチレン／アクリロニトリル共重合体、スチレン／ビニルメチルケトン共重合体、スチレン／ブタジエン共重合体、スチレン／イソプレン共重合体、スチレン／マレイン酸共重合体等のスチレン系共重合体；ポリアクリル酸メチル、ポリアクリル酸ブチル、ポリメタクリル酸メチル、ポリメタクリル酸ブチル等のアクリル酸エステル系単重合体やその共重合体；ポリ塩化ビニル、ポリ酢酸ビニル等のポリビニル誘導体；ポリエステル系重合体、ポリウレタン系重合体、ポリアミド系重合体、ポリイミド系重合体、ポリオール系重合体、エポキシ系重合体、テルペン系重合体、脂肪族または脂環族炭化水素樹脂、芳香族系石油樹脂などが挙げられ、単独あるいは混合して使用できるが特にこれらに限定するものではない。中でも、スチレン−アクリル系共重合樹脂、ポリエステル系樹脂、ポリオール系樹脂より選ばれる少なくとも１種以上であることが、電気特性、コスト面等から、より好ましいものである。更には、良好な定着特性を有するものとして、ポリエステル系樹脂および／またはポリオール系樹脂の使用が、一層好ましい。
【００６１】
また、該電子写真用トナーに使用される着色剤としては、従来からトナー用着色剤として使用されてきた顔料及び染料が使用でき、具体的には、カーボンブラック、ランプブラック、鉄黒、群青、ニグロシン染料、アニリンブルー、フタロシアニンブルー、フタロシアニングリーン、ハンザイエローＧ、ローダミン６Ｃレーキ、カルコオイルブルー、クロムイエロー、キナクリドンレッド、ベンジジンイエロー、ローズベンガル等を単独あるいは混合して用いることができる。
【００６２】
更に、必要により、トナー粒子自身に磁気特性を持たせるには、フェライト、マグネタイト、マグヘマタイト等の酸化鉄類、鉄、コバルト、ニッケル等の金属あるいは、これらと他の金属との合金等の磁性成分を単独または混合して、トナー粒子へ含有させればよい。また、これらの成分は、着色剤成分として使用／併用することもできる。
【００６３】
更に、トナー定着時にオイル等の離型剤を用いない、いわゆるオイルレス定着方式を使用するには、トナー粒子中に、ポリエチレンワックス、プロピレンワックス、カルナウバワックス等のワックス類を含有させることにより実現できる。これらの使用量としては、用いる材料の種類や定着の方法にもよるが、およそ０．５〜１０．０重量％程度の使用が好ましく、３．０〜８．０重量％程度の使用が更に好ましい。
【００６４】
この他、帯電の立ち上がりをより良くするための電荷制御剤としては、一般に知られているものが使用でき、例えば、アミノ基含有ビニル系コポリマー、四級アンモニウム塩化合物、ニグロシン染料、ポリアミン樹脂、イミダゾール化合物、アジン系染料、トリフェニルメタン系染料、グアニジン化合物、レーキ顔料等の正帯電性電荷制御剤や、カルボン酸誘導体及びこの金属塩、アルコキシレート、有機金属錯体、キレート化合物等の負帯電性電荷制御剤を、単独または混合して、トナー粒子中への混練物および／または添加物とすることができる。これら電荷制御剤を分散状態で用いる場合、キャリア粒子表面との相互作用が略均等に生じるためには、その分散径は、２．０μｍ以下であることが好ましく、１．０μｍ以下であることが更に好ましいものである。
【００６５】
トナー流動性や環境依存性改良のための添加剤としても、一般に公知のものが使用でき、例えば、酸化亜鉛、酸化錫、酸化アルミニウム、酸化チタン、酸化珪素、チタン酸ストロンチウム、チタン酸バリウム、チタン酸カルシウム、ジルコン酸ストロンチウム、ジルコン酸カルシウム、チタン酸ランタン、炭酸カルシウム、炭酸マグネシウム、マイカ、ドロマイト等の無機粉末や、これらの疎水化物が単独または混合して使用できる。この他の添加剤として、ポリテトラフルオロエチレン、テトラフルオロエチレンヘキサフルオロプロピレン共重合体、ポリフッ化ビニリデン等のフッ素樹脂微粒子をトナー表面改質剤として使用しても良い。これらは、添加する材料の種類にもよるが、トナー母体粒子１００重量部に対して、およそ０．１〜１０重量部程度を外添し、必要であれば適当な混合機により混合してトナー粒子表面に付着、凝着或いは、トナー粒子間隙で遊離した状態になるよう調整し、用いることができる。
【００６６】
本発明の現像剤中のトナー粒子製造方法としては、上述のような原材料を、二本ロール、二軸押出し混練機、一軸押出し混練機等の、公知の方法で混練し、これを機械式や気流式等の公知の粉砕、分級を行ないトナー母体粒子を作成することができる。また混練時に、着色剤や磁性体の分散状態を制御するための分散剤等を併用しても良い。更に、このトナー母体粒子は、前述の添加剤を添加し、混合機等により混合・表面改質を行なっても良い。
【００６７】
また、これらのトナー粒子の帯電電荷量は、実使用プロセスにより異なるため一概に決定できるものではないが、おおよそ、本発明の構成によるキャリア粒子との組み合わせにおいて、絶対値で３〜４０μＣ／ｇ程度の飽和電荷量であることが好ましく、更には５〜３０μＣ／ｇ程度の飽和電荷量であることが、より好ましい。
【００６８】
更に、第１３の構成の本発明は、トナー粒子の個数基準１０％径が、２．５μｍ以上であることを特徴とする前記第１２の構成に記載の電子写真用現像剤である。
これまでにも述べているように、本発明の構成は、トナー粒子とキャリア粒子の接触領域及びその近傍での、両者の接触・摩擦・剥離の状態を制御するものである。本発明のキャリア粒子表面複合化の程度を越えるような、あまりにも小さなトナー粒子が多く存在するような場合には、これらのトナー粒子が、比較的相互作用力の大きな組成が占有する領域にとりつき、長期の使用によって、トナー粒子成分固着として現れることがある。
【００６９】
したがって、本発明の構成によるキャリア粒子を使用した電子写真用現像剤では、このような微小粒径のトナー粒子数はできるだけ少ないほうが好ましく、具体的には、２．５μｍ以下の微小なトナー粒子が１０個数％以下、すなわち個数基準１０％径が２．５μｍ以上であることが好ましい。
【００７０】
更に、第１４の構成の本発明は、前記第１２又は１３の構成に記載の電子写真用現像剤を充填したことを特徴としている現像剤容器である。
【００７１】
また、更に、第１５の本発明は、前記第１４の構成に記載の電子写真用現像剤を充填した容器を装填したことを特徴とする画像形成装置である。
【００７２】
【発明の実施の形態】
以下、図面によって、本発明の画像形成装置について説明する。
図５は、本発明の電子写真用現像剤を充填した容器を搭載する画像形成装置についての１例を示したものであって、画像形成装置本体内に装着された現像部（１）と、この現像部（１）に補給される本発明の電子写真用現像剤を充填した現像剤収納容器（２）と、この両者を接続する現像剤送流手段（３）を示す部分断面図である。
【００７３】
図５において、現像部（１）は、トナーとキャリアを混合して成る液体状のニ成分系の現像剤（Ｄ）を収容した本発明の電子写真用現像剤を充填した現像ハウジング（４）と、現像剤（Ｄ）を攪拌混合する第１及び第２の攪拌スクリュー（５）、（６）と、現像ローラ（７）とを有していて、当該現像ローラ（７）が、潜像担持体の感光体（８）に対向して配置されている。感光体（８）は、矢印で示す方向に回転駆動され、その表面に静電潜像が形成される。図中符号（２６）は、現像剤受入口（２３）に固定された接続部材（２４）の上にフィルター（２５）を介して又は介さず嵌合されたキャップである。
感光体（８）の周囲には、図示していない帯電手段、露光手段、転写手段、除電手段、クリーニング手段等、その他の公知のユニットが配置されたものである。
【００７４】
第１及び第２の攪拌スクリュー（５）、（６）が回転することにより、現像ハウジング（４）内の現像剤（Ｄ）が攪拌され、そのトナーをキャリアが互いに逆極性に摩擦帯電される。かかる現像剤（Ｄ）が、矢印方向に回転駆動される現像ローラ（７）の周面に供給され、その供給された現像剤は現像ローラ（７）の周面に担持され、当該現像ローラ（７）の回転によって、その回転方向に搬送される。次いで、この搬送された現像剤は、ドクターブレード（９）によって量を規制され、規制後の現像剤が感光体（８）と現像ローラ（７）との間の現像領域に運ばれ、ここで現像剤中のトナーが、感光体表面の静電潜像に静電的に移行し、その静電潜像がトナー像として可視像化される。
【００７５】
次に、略図を用いて、本発明のキャリア粒子表面構造について説明を加える。まず、図１は本発明の構成の、キャリア粒子表面複合状態の概念図の一例である。この場合、相互作用力の異なる領域は３箇所に分かれている。図２は、図１のＸ−Ｙ部分での、位相変移量であり、Ｅｍａｘ、Ｅｍｉｎ及びＥａｖｇの大きさを併記している。但し、Ｅａｖｇは、各領域の占有面積基準で計算される。また、この例では領域３が、最大の占有面積であり、この領域成分がＡｍｏｄとなる。また、この領域範囲においては、２μｍの直線線分が、単一領域のみに含まれることはない。
【００７６】
更に、図３は、本発明第７の構成のフラクタル次元を求める方法の例である。この例では、ＡからＡ’までの曲線を、実線線分を単位長さとした場合と、破線線分（実線線分の１／２）を単位長さとした場合の区分を示している。同様の区分を様々な長さの線分で行ない、線分長（ＡＡ’の距離を１とした場合の相対値）とＡＡ’を区分するために用いた線分の本数を両対数グラフにすると、図４となる。この勾配より、曲線ＡＡ’のフラクタル次元を求めることができる。
【００７７】
【実施例】
これより、実施例において本発明を更に詳細に説明するが、本発明は以下の実施例に限定されるものではない。また、ここで「部」は全て重量部を示す。
【００７８】
実施例１
（コート剤１）
ジメトキシシリコーン・ポリエチレンイミン複合樹脂 １０部
（ジメトキシシリコーン／ポリエチレンイミン＝３／１）
エタノール １００部
【００７９】
上記処方にて混合したコート剤１を用い、乾燥後の層厚が約１μｍとなる量を、コート温度＝６０℃で流動層スプレーコートより塗布・熱乾燥し、更に電気炉により大気雰囲気中で１６０℃、９０分間焼成して、本発明の表面性状を満たす表面コート層を形成した、キャリア粒子１−２を得た。
ここで、コア材粒子としては、重量平均粒径５０μｍの球形フェライト粒子を用いた。
【００８０】
（トナー母体粒子組成）
ポリエステル樹脂 ７９部
（ビスフェノールＡのエチレンオキサイド付加アルコール、
ビスフェノールＡのプロピレンオキサイド付加アルコール、
テレフタル酸、トリメリット酸の縮合重合物；
Ｍｗ＝約１２０００、ガラス転移点＝約６０℃）
カーボンブラック（三菱カーボン社製、＃４４） １５部
電荷制御剤（クロム含金属染料、保土谷化学工業社製；
AIZON SPILON BLACK TRH） １部
カルナウバワックス（野田ワックス社製） ５部
【００８１】
上記組成の混合物を、二本ロール混練機にて３０分間混練後、機械式粉砕機・気流式分級機により粉砕・分級条件を行ない、トナー母体粒子を得た。
更に、このトナー母体粒子１００部に対して、１部の割合で表面をジメチルシラン処理した疎水性シリカ微粒子を加えて、ヘンシェルミキサーにより、トータル２分間混合し、それぞれのトナー母体粒子に対応する試験用のトナー粒子１を得た。
トナー粒子１の粒度分布をコールターカウンターＴＡ２にて測定したところ、重量平均径Ｄ４＝６．５μｍ、累積個数分布から算出した個数基準１０％径＝２．８μｍであった。
【００８２】
キャリア粒子１−２の位相変移量分布の評価値を表１−１、表１−２に示す。
【００８３】
【表１−１】

【００８４】
【表１−２】

【００８５】
ここで、キャリア粒子表面コート層の位相変移量測定は、デジタル・インスツルメンツ社製走査型プローブ顕微鏡ＮａｎｏｓｃｏｐｅIIIａ、Ｄｉｍｅｎｓｉｏｎ３１００及び位相検出エクステンダーモジュール（ＰＨＡＳＥ−Ｄ０１型）を用いて行なった。
測定サンプルであるキャリア粒子は、アルミニウム平板上へ、薄く塗った接着剤によって固定した。走査範囲は５μｍ四方とし、各サンプルについて独立した３箇所を測定して、これらの分布測定データを元に各値を算出し、その平均値を取り評価値とした。
次に、各位相変移量分布測定範囲における、２μｍ線分をＡｍｏｄ領域及びＡｍｏｄ以外の領域が横切るかどうかを、位相変移量分布像を基に目視にて確認した。
引き続き、Ａｍｏｄとその他の領域の境界線について、単位長さの異なる５種類の線分を用い、線分長ｖｓ線分使用本数の両対数プロット勾配から、フラクタル次元を求めた。
【００８６】
また、キャリア粒子の電荷付与特性を評価するために、キャリア粒子１−２及びトナー粒子１を用いて、撹拌によるトナー粒子帯電量の立ち上がり試験を行なった。キャリア粒子とトナー粒子の混合比は、重量基準で９５：５とし、撹拌時間は１０秒、６０秒、６００秒とした。トナー帯電量の測定は、エレクトロメーター（６１０Ｃ；ケスレー社製）を用い、気流によりトナー粒子とキャリア粒子を分離しつつ帯電電荷量を測定する、いわゆるブローオフ法によって行なった。
【００８７】
更に、これらのキャリア粒子及びトナー粒子を用いて、リコー製複写機ｉｍａｇｉｏ ＭＦ−６５５０の改造機を用い、Ａ４版，画像面積率６％原稿３０万枚の連続画像出図試験を行ない、初期及び連続出図後の文字画像及びベタ画像を出力し画質評価を行なった。画質評価としては、文字部分での地肌カブリ、ベタ画像での画像濃度の安定性及び各画像でのその他不具合の有無を評価した。画像濃度については、マクベス濃度計（ＲＤ−９１４）を用いて計測し、その他の項目については、目視により評価した。
【００８８】
画像出力時の像担持体上静電荷像は、地肌部＝−７００Ｖ、画像部＝−２００Ｖとした。また、現像スリーブには、直流の現像バイアス電位を印加した。
３０万枚の連続画像出図試験終了後の各現像剤を採取し、エアーブローにより表面に付着しているトナー粒子を除去後、残ったキャリア粒子の一定量をトルエン中に分散して、上澄みを採取し、溶出したトナー粒子成分固着物の量を評価した。固着物量の評価には、対比として未使用のキャリア粒子を用い、同様の方法により採取した上澄み液における、白色可視光透過率と、試験サンプルの白色可視光透過率の差を表面固着成分量の差と捉え、各サンプルを相対評価した。透過率の測定には、分光光度計ＴＣ−１８００（東京電色社製）を用い、Ｃ５０光源を用いて行なった。
同様に３０万枚連続画像出図試験終了後の各現像剤より得たキャリア粒子表面コート層の削れ度合を蛍光Ｘ線による元素分析を用いて測定した。測定は、コート層を設けないコア材、試験前のキャリア粒子及び試験後のキャリア粒子を同時測定し、特定元素のＸ線強度から、コート層の摩耗率（％）を算出した。
【００８９】
以上の試験・評価を行なったところ、実施例１のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が極めて少ないキャリア粒子であることが確認された。
【００９０】
初期及び３０万枚後の、各評価結果について、表３−１、表３−２に示す。
【００９１】
実施例２
電気炉による焼成条件を、焼成温度＝２００℃、焼成時間＝３０分として、実施例１より焼成温度を上げ、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つキャリア粒子１−４を得た。
キャリア粒子１−４を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
【００９２】
実施例２のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が極めて少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【００９３】
実施例３
（コート剤３）
ポリシラザン ７部
ブチルメタクリレート ３部
カーボンブラック １部
トルエン １００部
【００９４】
本発明の別の処方例として、コート剤３を用い、コート温度＝９０℃、焼成温度＝２００℃、焼成時間＝３０分として、実施例１と異なるコート剤処方によりキャリア粒子表面性状を調整し、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子３−１を得た。
キャリア粒子３−１を用いた以外は、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例３のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が極めて少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【００９５】
実施例４
（コート剤４）
ポリイミド ５部
アクリル樹脂 ５部
カーボンブラック １部
トルエン １００部
【００９６】
本発明の更に別の処方例として、コート剤４を用い、コート温度＝９０℃、焼成温度＝２５０℃、焼成時間＝９０分として、コート剤処方によりキャリア粒子表面性状を調整し、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子４−２を得た。
キャリア粒子４−２を用いた以外は、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例４のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗が極めて少なく、トナー成分固着量も充分に少ないキャリア粒子であることが確認された。
各評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【００９７】
参考例１
電気炉による焼成条件を、焼成温度＝１２０℃、焼成時間＝９０分として、実施例１より焼成温度を下げ、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子１−１を得た。
キャリア粒子１−１を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
参考例１のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が極めて少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【００９８】
実施例５
（コート剤２）
ジメトキシシリコーン・ポリエチレンイミン複合樹脂 １０部
（ジメトキシシリコーン／ポリエチレンイミン＝１／３）
エタノール １００部
【００９９】
本発明のまた更に別の処方例として、コート剤１と複合化率の異なるコート剤２を用い、コート温度＝６０℃、焼成温度＝１６０℃、焼成時間＝９０分として、コート剤複合化率によりキャリア粒子表面性状を調整して、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子２−２を得た。
キャリア粒子２−２を用いた以外は、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例５のキャリア粒子は、ランニング後においても、初期と比較して帯電性能の変化が小さく、ほぼ同等の画質が得られ、コート層摩耗が充分に少なく、トナー成分固着量も少ないキャリア粒子であることが確認された。
各評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１００】
実施例６
電気炉による焼成条件を、焼成温度＝２００℃、焼成時間＝９０分として、実施例５より焼成温度を上げ、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子２−３を得た。
キャリア粒子２−３を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行った。
実施例６のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が充分に少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０１】
実施例７
電気炉による焼成条件を、焼成温度＝１６０℃、焼成時間＝１８０分として、実施例５より焼成時間を長くすることにより、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子２−４を得た。
キャリア粒子２−４を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例７のキャリア粒子は、ランニング後においても、初期と比較して帯電性能の変化が小さく、ほぼ同等の画質が得られ、コート層摩耗やトナー成分固着量が少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０２】
実施例８
電気炉による焼成条件を、焼成温度＝２５０℃、焼成時間＝３０分として、実施例３より焼成温度を上げ、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子３−２を得た。
キャリア粒子３−２を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例８のキャリア粒子は、ランニング後においても、初期と比較して帯電性能の変化が小さく、同等の画質が得られ、コート層摩耗が少なく、トナー成分固着量が充分に少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０３】
実施例９
電気炉による焼成条件を、焼成温度＝２５０℃、焼成時間＝６０分として、実施例８の焼成時間を長くして、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子３−３を得た。
キャリア粒子３−３を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例９のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗やトナー成分固着量が充分に少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０４】
実施例１０
電気炉による焼成条件を、焼成温度＝２００℃、焼成時間＝９０分として、実施例４より焼成温度を下げ、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子４−１を得た。
キャリア粒子４−１を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例１０のキャリア粒子は、ランニング後においても、初期と比較して帯電性能の変化が小さく、同等の画質が得られ、コート層摩耗が少なく、トナー成分固着量が充分に少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０５】
実施例１１
電気炉による焼成条件を、焼成温度＝２５０℃、焼成時間＝２４０分として、実施例４より焼成時間を長くし、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状を満足する表面コート層を持つ、キャリア粒子４−３を得た。
キャリア粒子４−３を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
実施例１１のキャリア粒子は、ランニング後においても、初期と比較してほとんど帯電性能が変化せず、同等の画質が得られ、コート層摩耗が少なく、トナー成分固着量が極めて少ないキャリア粒子であることが確認された。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０６】
比較例１
電気炉による焼成条件を、焼成温度＝２００℃、焼成時間＝９０分として、実施例２より焼成時間を長くすることにより、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状から逸脱した表面コート層を持つ、キャリア粒子１−３を得た。
キャリア粒子１−３を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
比較例１のキャリア粒子は、初期においても、帯電性能が不十分であるため、地肌カブリが多いばかりでなく、ランニング試験によるコート層の摩耗がひどく、実用には全く耐えないものであった。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０７】
比較例２
電気炉による焼成条件を、焼成温度＝１２０℃、焼成時間＝９０分として、実施例５より焼成温度を低くすることにより、キャリア粒子表面性状を調整した以外は同様にして、本発明の表面性状から逸脱した表面コート層を持つ、キャリア粒子２−１を得た。
キャリア粒子２−１を用いて、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
比較例２のキャリア粒子は、初期においては、充分な帯電性能を持ち、良好な画像品質が得られるものの、ランニング試験によるトナー成分の固着に伴い帯電性能が劣化し、３０万枚のランニングですでに実用には全く耐えない画像品質となった。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。
【０１０８】
比較例３
（コート剤５）
アクリル樹脂 １０部
カーボンブラック １部
トルエン １００部
【０１０９】
複合コート層とならない処方例として、コート剤４の複合部分を除いたコート剤５を用い、実施例１０と同様に、コート温度＝９０℃、焼成温度＝２００℃、焼成時間＝９０分の製造条件にて、キャリア粒子表面性状を調整し、本発明の表面性状から逸脱した表面コート層を持つ、キャリア粒子５−１を得た。
キャリア粒子５−１を用いた以外は、実施例１と同様のキャリア粒子表面性状評価、帯電量評価及び画像評価を行なった。
比較例３のキャリア粒子は、初期においても、帯電性能が不十分であるため、地肌カブリが多いばかりでなく、ランニング試験によりトナー成分の固着がひどく、更に帯電性能が低下してしまい、実用には全く耐えないものであった。
各測定・評価結果について、表１−１、表１−２、表３−１、表３−２に示す。使用したキャリア粒子と、実施例・比較例の対応は表２に一覧する。
【０１１０】
【表２】

【０１１１】
実施例１２〜１４
更に、実施例１のキャリア粒子１−２、実施例８のキャリア粒子３−２、実施例７のキャリア粒子２−４に対して、トナー母体粒子の粉砕・分級条件を変更し、重量平均径Ｄ４＝６．３μｍ、個数基準１０％径＝２．３μｍに調整した以外は、トナー粒子１と同様にしたトナー粒子２と組み合わせて、各実施例と同様の画像評価を行なったところ、ランニング後においても、充分に実用上問題のない画像品質が得られた。
各評価結果について、表３−１、表３−２に示す。
【０１１２】
【表３−１】

地肌カブリランク ◎：極めて優れる
○：実用上問題無し
△：許容レベル
×：使用不可
【０１１３】
【表３−２】

地肌カブリランク ◎：極めて優れる
○：実用上問題無し
△：許容レベル
×：使用不可
【０１１４】
【発明の効果】
以上、本発明の構成によれば、表１−１、表１−２におけるキャリア粒子特性値及び表３−１、表３−２に見られる実施例および比較例の対比を含む詳細且つ具体的な説明から明らかなように、キャリア粒子表面コート層の摩耗やトナー粒子成分のキャリア粒子への固着が、長期に渡って極めて少なく、これに伴う画像濃度の低下や、トナーチリ・地肌カブリといった画像劣化の無い安定した画像を得るに必要な特質を持つと同時に、高精細・高解像度の高品質画像を得るのに、極めて有効な電子写真用キャリア及び電子写真用二成分現像剤であるという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の構成の、キャリア粒子表面複合状態の概念図の一例である。
【図２】図１の複合表面の位相変移量分布（ＸＹ断面）を表わす図である。
【図３】本発明の構成の、境界線のフラクタル次元分割例を表わす図である。
【図４】フラクタル次元計算例を表わす図である。
【図５】本発明の電子写真用現像剤を充填した容器及びその容器を搭載した画像形成装置を示した図である。
【符号の説明】
１ 現像部
２ 現像剤収納容器
３ 現像剤送流手段
４ 現像ハウジング
５ 攪拌スクリュー
６ 攪拌スクリュー
７ 現像ローラ
８ 感光体
９ ドクターブレード
２３ 現像剤受入口
２４ 接続部材
２５ フィルター
２６ キャップ
Ｄ 現像剤[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called carrier particle, which is a charge imparting member that imparts a charge to toner particles by stirring together with the toner particles, and a two-component developer containing at least the toner particles and the carrier particles.
[0002]
[Prior art]
Conventionally, in electrophotographic image formation, a latent image by an electrostatic charge is formed on an image carrier such as a photoconductive substance, and charged toner particles are attached to the electrostatic latent image to form a visible image. Forming. The visible image formed by the toner is finally transferred to a transfer medium such as paper, and then fixed to the transfer medium by heat, pressure, solvent gas, or the like, and becomes an output image.
[0003]
These image forming methods include a so-called two-component development method in which toner particles for charging a toner image are charged, friction charging by stirring and mixing of toner particles and carrier particles, and without using carrier particles. It is roughly divided into a so-called one-component development system that applies charge to toner particles. The one-component development method is classified into a magnetic one-component development method and a non-magnetic one-component development method depending on whether or not magnetic force is used to hold toner particles on the developing roller.
[0004]
Up to now, in copiers that require high speed and image reproducibility, and multi-function machines based on this, two components are required due to the requirements of toner particle charging stability, rise-up performance, long-term image quality stability, etc. Many developing methods have been adopted, and one-component developing methods have been often used for small printers, facsimiles, and the like, which require large space savings and low costs.
[0005]
In recent years, due to consideration for environmental impact, recycling and reuse of units mainly used in the one-component development system is being realized, and at the same time, the life of the developer can be further extended in the two-component development system. There is an increasing demand.
[0006]
On the other hand, from the viewpoint of reducing energy consumption, the temperature at which the toner image is fixed is becoming lower, and in order to enable fixing with lower energy, the toner particles are likely to be deformed and fixed at a lower temperature. Yes.
[0007]
Causes of deterioration of the two-component developer include (i) abrasion of the carrier particle surface, (ii) peeling of the carrier surface coat layer, (iii) crushing of the carrier particle, and (iv) on the carrier particle of the toner particle component. Deterioration of charging performance, transition from desired electrical resistance, and generation of debris and abrasion powder due to adhesion to the surface. These factors are the cause of this, resulting in decreased image density, background fogging, and decreased resolution. Degradation of the image forming system such as image quality, physical / electrical damage of the image carrier, contamination of the charging member, and the like are caused.
[0008]
In order to solve the above-described problems, many proposals having some effects have been made so far.
Among these, as a proposal paying attention to the coating layer of the carrier particles, especially the so-called coated carrier particles provided with the coating layer on the surface of the magnetic particles, in Japanese Patent Application Laid-Open No. 9-269614, resin particles and conductive fine powder are included in the matrix resin. A resin coating layer containing a dispersion of the toner is shown to prevent spent by the toner for a long period of time. In JP-A-9-31504, a spherical composite core particle composed of iron oxide particle powder and a cured phenol resin is used. It is described that a stable triboelectric charge and durability can be obtained by having a coating layer made of a phenol resin containing an amino group cured on the surface and defining the iron oxide particle content and amino group content. -31505 discloses melamine on the surface of spherical composite core particles composed of iron oxide particle powder and a cured phenol resin. One or two or more types selected from fats, aniline resins and urea resins and a cured coating layer of a phenol resin are described, and a carrier that obtains stable triboelectric charging and durability is described in JP-A-10-198078. By dispersing resin fine particles and conductive fine particles in the matrix resin of the carrier particle coating layer and containing 10% or more of the same resin component that constitutes the binder resin of the toner, the toner spent for charging performance In Patent No. 2777976, the surface of particles composed of ferromagnetic fine particles and a cured phenol resin is made of epoxy resin, polyester resin, styrene resin, silicon resin and fluororesin. It is described that a magnetic carrier having a controlled charge amount can be obtained by coating with one or more kinds. Patent No. 2825295 describes that a magnetic carrier having a high electrical resistance and a small bulk density is obtained by coating the surface of particles composed of ferromagnetic fine particles and a cured phenol resin with a melamine resin. Patent No. 2905563 In the book, it is shown that the surface of particles made of ferromagnetic fine particles and a cured phenol resin is uniformly coated with a polyamide layer to obtain a magnetic carrier having a high electric resistance and a small bulk density.
[0009]
However, in the proposals as described above, while the fixing temperature is further lowered and the life of the carrier particles is expected to be longer than before, sufficient effects may not be maintained yet.
[0010]
For example, in the one described in JP-A-9-269614, since the matrix resin occupies most of the surface of the carrier particles, the adherability of the toner particle component mainly depends on the surface state of the matrix resin. The function of preventing spent is not always expressed. When toner particles capable of lowering the fixing temperature are used, in the method as disclosed in Japanese Patent Application Laid-Open No. 10-198078, a portion of the same component as the binder resin component of the toner on the carrier surface is a starting point for fixing the toner particle component. In some cases, the toner charge amount becomes unstable from the initial stage of stirring.
[0011]
On the other hand, in the thing of Unexamined-Japanese-Patent No. 9-31505, the charge imparting ability to a certain amount of toner particles and carrier particle durability can be achieved by optimizing the combination of the surface coat layer resins described and the composite state thereof. Although the carrier particle surface in the proposal has a uniform resin composition, its microscopic surface state is not disclosed at all, and the carrier particle surface that directly contacts and rubs with toner particles in actual use is not disclosed. , Remained unclear. In other words, even with the proposed composition, the function of preventing the adhesion of the toner particle component does not always fully appear as in the case of the above example.
[0012]
As described above, in the two-component developer, the toner particles and the carrier particles are agitated to be peeled / tribally charged to give the toner particles a sufficient amount of charge, and the toner particle components are fixed for a long time. Therefore, the carrier particle surface state necessary for preventing the carrier particle is not clarified at all, and therefore it is very difficult to achieve both sufficient toner charge amount and further extension of the carrier particle life. It was left as an issue.
[0013]
[Problems to be solved by the invention]
In view of the present problems as described above, the present invention is capable of maintaining a sufficient toner particle charge amount without causing the toner layer component to adhere to the coating layer for a very long period of time. It is an object of the present invention to provide a carrier particle having a very high function and a two-component developer using the same.
[0014]
[Means for Solving the Problems]
In order to prevent the toner particles from sticking to the carrier particles and to prevent the carrier particles from being worn while giving a sufficient charge to the toner particles, the toner particles and the carrier particles are in contact with each other. It is important to control the surface physical properties, such as composition, adhesion, friction, viscoelasticity, etc., in the minute contact area so that they are within an appropriate range, and the area with each surface physical property is appropriately combined. .
[0015]
As a result of diligent research, the present inventors have found that a minute composite structure on the surface of the carrier coat layer or the vicinity of the extreme surface has a local impact force / friction force generated when the toner particles and the carrier particles are agitated / frictioned, or between the carrier particles. This contributes to the magnitude of impact due to collision and friction of the toner, and it appears as the occurrence of sticking of the toner particle component to the carrier particles and the increase / decrease in the wear / peeling of the carrier coat layer, greatly changing the developer life (durability). It was confirmed. Therefore, by controlling the composite structure of the carrier particle coat layer in a minute region where carrier particles and toner particles are in contact with each other, the state that occurs when the developer is agitated, such as contact, separation, and friction between toner particles and carrier particles. It was found that the above-mentioned various problems can be solved with a high degree of control, and an index expressing the surface physical properties of the carrier particle coat layer microregion required at this time and its range were specified, and the present invention was completed. .
[0016]
  Therefore, the above-mentioned problem is (1) “in an electrophotographic carrier in which a coating layer containing at least a resin phase is provided on the surface of a core material made of at least a magnetic material, and the carrier particle surface is tapped by a scanning probe microscope. Regions with different phase shifts by phase shift measurement (Phase Imaging) in mode scanning are formed, the area of the component A (i) region occupying the surface of the carrier particle is S (i), and the phase in the component A (i) region When the shift amount is E (i) (i is the number of regions having 1 to different phase shift amounts), the occupied area reference average value Eavg = Σ (E (i) · S (i)) / Ratio S0 / ΣS (i) × 100 = the total area S0 of the area of the area having a phase shift amount exceeding ΣS (i)24-90% electrophotographic carrier (Σ represents total) ", (2)" Proportion S0 / ΣS (i of total area S0 having a phase shift amount exceeding Eavg " ) × 100 =24The carrier for electrophotography according to the item (1), characterized in that it is ˜75% ”, (3)“ the ratio S0 / ΣS (% of the total area S0 having a phase shift amount exceeding the Eavg ” i) × 100 =24The electrophotographic carrier according to the above item (1), characterized in that it is ˜50% ”, (4)“ area ratio when the area occupied by the component Amin having the minimum phase shift amount Emin is Smin ” Smin / ΣS (i) × 100 ≦ 80%, wherein the electrophotographic carrier according to any one of the above items (1) to (3) ”, (5)“ maximum phase ” Any one of the items (1) to (4), wherein the area ratio Smax / ΣS (i) × 100 ≦ 60% when the area occupied by the component Amax having the shift amount Emax is Smax. (1) to (6), wherein Emin and Emax satisfy a relational expression of 0.2 ≦ Emin / Emax ≦ 0.7. 5) the electrophotographic carrier according to any one of items 5), 7) "The electrophotographic carrier according to any one of (1) to (6) above, wherein the region occupied by Amin and / or Amod contains silicon atoms", (8) “The electrophotographic carrier according to any one of Items (1) to (7), wherein the region occupied by Amax and / or Amod contains a nitrogen atom”, (9) “Carrier The electrophotographic carrier according to any one of items (1) to (8), wherein any region occupying the particle surface includes a siloxane bond. Any region that occupies the particle surface includes a structure having a polysilazane skeleton, and is achieved by the “electrophotographic carrier according to any one of items (1) to (9)”. The
[0017]
  In addition, the above problem is11) “In an electrophotographic developer obtained by mixing electrophotographic carrier particles and toner particles containing at least a binder resin and a colorant, the carrier particles are the above-mentioned items (1) to (10And an electrophotographic carrier according to any one of the above items).
[0018]
  In addition, the above problem is12) “The toner particle number-based 10% diameter is 2.5 μm or more.11It is achieved by the electrophotographic developer described in the item).
[0021]
Hereinafter, the present invention will be described in detail.
As described above, according to the first aspect of the present invention, in the electrophotographic carrier in which the coating layer including at least the resin phase is provided on the surface of the core material made of at least the magnetic material, the surface of the carrier particle is the same as that of the scanning probe microscope. Regions having different phase shift amounts by phase shift measurement in tapping mode scanning (Phase Imaging) are formed, the area of the component A (i) region occupying the surface of the carrier particle is S (i), and the component A (i) region is When the phase shift amount is E (i) (i is 1 to the number of regions having different phase shift amounts), the occupied area reference average value Eavg = Σ (E (i) · S (i)) of the phase shift amount The carrier for electrophotography is characterized in that the ratio S0 / ΣS (i) × 100 = 10 to 90% of the total area S0 of the area having a phase shift amount exceeding / ΣS (i). Here, Σ represents the total of each component, and Σ (E (i) · S (i)) = E (1) · S (1) + E (2) · S (2) + ... + E (i) · S (i).
[0022]
By making the surface of the carrier particle coat layer in this way, the toner particles are sufficiently charged by friction / peeling charging between the carrier particles and the toner particles, and the toner particle component is fixed to the carrier particles and the carrier particle surface coat layer. A high degree of suppression of wear can be achieved.
[0023]
In order to carry out friction / peeling charging by mixing and stirring toner particles and carrier particles, a portion (hereinafter referred to as a toner charging site) capable of receiving a charge corresponding to the toner polarity on the surface of the toner particles or in the vicinity of the toner particles, and a carrier Mechanical action such as contact, friction, and peeling is required between the surface of the particle or a portion (hereinafter referred to as a carrier charging site) that can supply a charge corresponding to the toner polarity. There is a method of increasing the stress (hereinafter referred to as interaction force) generated during friction / contact / separation between toner particles and carrier particles when rapidly transferring large charges by such a method. When the interaction force is uniformly large on the entire surface, there is no portion where the toner particles and the carrier particles are easily separated. Causes wear and delamination. On the other hand, in the form where the interaction force is evenly small, it is difficult for the toner particle component to be fixed and the carrier surface coat layer to be worn and peeled off, but it takes a long time for the toner particles to have a stable charge.
[0024]
According to the above configuration, since there are regions where the interaction force between the toner particles and the carrier particles is different, sufficient friction / peeling charging is quickly performed by the action of the large holding force generated in the region where the interaction force is large. In addition, due to the relatively small holding force in the region where the interaction force is small, the toner particles can be prevented from sticking without staying at a specific location on the surface of the carrier particles.
[0025]
When the proportion of S0 is outside the range of 10 to 90%, the region having a large interaction force on the surface of the carrier particle and the region having a small interaction force are too many. The same phenomenon is likely to occur. In order to further control the balance of the interaction force, the proportion of S0 is preferably 20 to 75%, more preferably 20 to 50%.
[0026]
Here, the phase shift amount in the tapping mode scan of the scanning probe microscope (hereinafter referred to as SPM) is a direct index representing the strength of the interaction force at each measurement point, and the phase shift amount on the surface of the carrier particle. The distribution can express the distribution of the interaction force between the toner particles and the carrier particles, and also represents the ratio between the small part and the large part of the interaction force.
[0027]
The distribution of the phase shift amount can be known as follows.
First, carrier particles provided with a surface coat layer are fixed to a sufficiently rigid support. At this time, a double-sided tape, an adhesive, or the like may be used for fixing as necessary. Next, the sample on which the particles are fixed is set at the SPM measurement site in an environment of room temperature and normal pressure. Subsequently, so-called tapping mode scanning is performed in which the measurement surface is scanned within the scanning range of about 2 to 200 μm and the sample surface is scanned while vibrating the measurement probe at the resonance frequency. At this time, the radius of curvature of the probe tip is preferably about 5 to 20 nm, and the tapping frequency is preferably about 150 to 450 kHz. Under the above conditions, tapping mode scanning is performed, and the phase shift amount can be measured by detecting the phase delay of the AC signal output in tapping mode scanning with respect to the AC signal input to vibrate the probe. By measuring the phase shift amount at each point, the phase shift distribution in the scanning range can be expressed. Here, the phase shift amount is large in the surface region where the interaction force is large, and the phase shift amount is detected small in the region where the interaction force is small.
[0028]
As long as the first aspect of the present invention can take the above-mentioned range, the material is not limited, and a conventionally known material can be used. For example, as an example of inorganic / metal magnetic particles that can be used as a core material of carrier particles Includes metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite, but are not limited thereto. These magnetic particles may be used in any form of core material such as single crystal / amorphous particles, single / composite sintered bodies, and particles in which single / composite particles are dispersed in a polymer such as resin. good. In order to achieve both the magnetic properties of the carrier particles and the dispersibility of the magnetic particles with the particles in which the magnetic particles are dispersed in the polymer, these magnetic particles include particles having a size of about 0.5 to 10 μm. It is preferable.
[0029]
Next, as the resin for forming the core material particles and / or the surface coat layer of the carrier particles, for example, polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene; polystyrene, acrylic (for example, polymethyl methacrylate) Polyvinyl and polyvinylidene resins such as polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone; vinyl chloride-vinyl acetate copolymer; silicone resin comprising an organosiloxane bond or Modified products (for example, modified products by alkyd resin, polyester resin, epoxy resin, polyurethane, etc.); perhydropolysilazane or modified products thereof (parts) (Including oxidized products); fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyamide; polyester; polyurethane; polycarbonate; urea resin; melamine resin; benzoguanamine resin; Etc. A composite of a silicone resin and a polyethyleneimine resin, a silicone resin and a polyolefin resin, a composite of a perhydropolysilazane resin and a polyolefin resin is preferable, and a composite of a silicone resin and a polyethyleneimine resin is particularly preferable. These resins can be modified and used to be partially compatible with each other, or partially have chemical bonds and used as block polymers, graft polymers, or intermediate products thereof. Further, it is more preferable to immobilize by a crosslinking reaction or the like in the process of forming the coat layer.
[0030]
As the silicone resin, a conventionally known silicone resin may be used, and examples thereof include straight silicone consisting only of an organosiloxane bond represented by the following formula and a silicone resin modified with alkyd, polyester, epoxy, urethane and the like.
[0031]
[Chemical 1]

R in the above formula₁Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R₂And R_ThreeIs a hydrogen group, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, a phenoxy group, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a hydroxy group, a carboxyl group, an ethylene oxide group, A glycidyl group or a group represented by the following formula.
[0032]
[Chemical 2]

R in the above formula_Four, R_FiveIs a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a phenyl group , Phenoxy group, k, l, m, n, o, p represents an integer of 1 or more.
[0033]
Each of the above substituents may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, or a halogen atom in addition to an unsubstituted one. .
[0034]
The polysilazane may be a perhydropolysilazane which does not contain a conventionally known substituent. A part of the hydrogen atom may be an alkyl group, a phenyl group, an alkylphenyl group, an alkenyl group, a halide thereof, a sulfo group. It may be a partially substituted polysilazane substituted with a group, a phosphino group, a phosphinyl group, a phosphinothioyl group, or a complex polymer thereof.
[0035]
Further, as described above, the material used for controlling the electric resistance of the carrier core material particles and / or the coating layer by the dispersion of the low-resistance material particles may be a conventionally known material, and examples thereof include iron, gold, Examples include metals such as copper; iron oxides such as ferrite and magnetite; and pigments such as carbon black.
[0036]
Among these, in particular, the use of a mixture of furnace black and acetylene black, which is one of carbon blacks, can effectively adjust the conductivity with the addition of a small amount of low resistance fine powder, and is preferably used. These low-resistance fine powders preferably have a particle size of about 0.01 to 10 μm, and are preferably added in an amount of 2 to 30 parts by weight with respect to 100 parts by weight of the core material particles or the coat layer resin, 20 parts by weight is preferred.
[0037]
In addition, in the carrier core material particles and / or the coating layer, a coupling agent such as a silane coupling agent or a titanium coupling agent is assisted in order to improve the adhesion or the dispersibility of the resistance control material. It may be added as an agent.
[0038]
Examples of the silane coupling agent used in the present invention include compounds represented by the following general formula.
[0039]
[Chemical 3]

However, X_ThreeIs a hydrolyzable group bonded to a silicon atom and includes a chloro group, an alkoxy group, an acetoxy group, an alkylamino group, and a propenoxy group.
Y is an organic functional group that reacts with the organic matrix and includes a vinyl group, a methacryl group, an epoxy group, a glycidoxy group, an amino group, a mercapto group, and the like.
R is a C1-C20 alkyl group or alkylene group.
[0040]
Among these silane coupling agents, an aminosilane coupling agent having an amino group in Y is preferable for obtaining a negatively charged developer, and Y has an epoxy group in order to obtain a positively charged developer. Epoxy silane coupling agents are preferred.
As a method for producing the carrier of the present invention, the coating layer forming liquid may be applied to the surface of the core material particles by means such as spraying or dipping.
In particular, the coating liquid containing the resin composition and the solvent is applied while heating at least the core material made of a magnetic material, thereby removing the solvent in the coating liquid and fixing the resin component on the surface of the core material. It is preferable to form the coat layer by heating to a temperature higher than the temperature at the time of coating.
By adopting such a production method, a coating layer composition having a structure conforming to the configuration of the present invention, in which the resin composition contained in the coating liquid is homogeneously combined, can be formed on the surface of the core material.
The thickness of the coating layer is preferably 0.1 to 20 μm.
[0041]
As a second configuration of the present invention, the area ratio Smin / ΣS (i) × 100 is 80% or less, where Smin is an area occupied by the component Amin having the minimum phase shift amount Emin. The electrophotographic carrier according to the first configuration.
[0042]
In order to achieve a more stable interaction force balance, which is the gist of the present invention, it is preferable that the occupancy ratio of the region with the smallest interaction force is 80% or less of the entire surface, and exceeds this. In such a case, the probability that the toner particles come into contact with the region where the interaction force is minimum is too high, so that the time to reach a stable toner charge amount, that is, so-called toner charge rise may be delayed.
[0043]
On the other hand, the present invention having the third configuration is characterized in that the area ratio Smax / ΣS (i) × 100 is 60% or less, where Smax is an area occupied by the component Amax having the maximum phase shift amount Emax. In contrast to the case of the present invention of the second configuration described above, the occupation ratio of the region with the largest interaction force is 60% of the entire surface. In such a case, the probability that the toner particles come into contact with the region having the maximum interaction force becomes too high, and the stability over time may not be sufficiently maintained. Furthermore, it is more preferable if the area range occupied by Amax is 45% or less.
[0044]
The fourth configuration of the present invention is any one of the first to third configurations, wherein Emin and Emax satisfy a relational expression of 0.2 ≦ Emin / Emax ≦ 0.7. Is an electrophotographic carrier.
When the values of Emin and Emax are too far apart and the ratio Emin / Emax is less than 0.2, the total value of the interaction force fluctuates due to a slight difference in manufacturing conditions. It is not preferable for obtaining the main carrier particles. On the other hand, when the values of Emin and Emax are close and the ratio Emin / Emax exceeds 0.7, the composite structure as the gist of the present invention becomes unclear, and quick toner particles by the combination are obtained. There may be cases where charging and long life are not fully achieved.
[0045]
In addition, since the magnitude of the interaction force between the toner particles and the carrier particle surface depends on the type of toner particles and the configuration of the two-component development process, it is difficult to express uniquely, and it is specified by a unique value. Is not to be done. Therefore, Emin and Emax are preferable as relative indicators when the range of the configuration of the fourth aspect of the present invention is 0.2 ≦ Emin / Emax ≦ 0.7, and is within the range of 0.25 to 0.5. Further preferred.
[0046]
The fifth aspect of the present invention is characterized in that the area ratio Smod / ΣS (i) × 100 ≦ 80% when the area of the component Amod occupying the maximum area on the surface of the carrier particles is Smod. The carrier for electrophotography according to any one of the first to fourth configurations.
[0047]
As described above, the function of the carrier particle is controlled by the combination and the composite state of the regions having different interaction forces on the surface of the carrier particle. Therefore, when the area of the region having the same interaction force exceeds the range of the present invention of the fifth configuration and takes a wide occupation area ratio, the operation of other regions may not be sufficiently exhibited. is there. Smod / ΣS (i) × 100 is more preferably 60 or less.
[0048]
According to the sixth aspect of the present invention, when an arbitrary line segment corresponding to a length of 2 μm is superimposed on the surface image representing the phase shift distribution on the surface of the carrier particle, the area occupied by Amod is overlapped with the line segment. 6. The electrophotographic carrier according to any one of the first to fifth configurations, wherein an area other than Amod occupies at least one location.
[0049]
On the surface of the carrier particles of the present invention, a region having a large interaction force and a region having a small interaction force are present in a composite state. The composite state of each region, particularly the region occupying the maximum area and other regions Depending on the composite state, the action of each region may be expressed alone.
[0050]
Therefore, in order to fully express the effect of the present invention, it is preferable that each surface region is highly complex, and specifically, it is preferable to take a state within the scope of the present invention of the sixth configuration. When the composite state of the surface does not satisfy this configuration, either the Amod region or the region other than Amod exists independently over the region exceeding the length of 2 μm. In such a composite state, when the toner particles and the carrier particles are actually agitated, there may be many component regions that are not involved in the contact in the contact region between them or in the vicinity thereof. By satisfying this configuration of the surface composite state, each region is substantially sufficiently composited, so that the toner particles can be contacted and frictioned substantially uniformly in any region on the carrier particles, This is more preferable in order to achieve both charge imparting to the toner particles and carrier particle life.
[0051]
Similarly, as another index indicating the degree of compositing, when a preferable state is shown with respect to the boundary line between the Amod region and the region other than Amod, the seventh configuration of the present invention can occupy the region occupied by Amod and the occupation other than Amod. The electrophotographic carrier according to any one of the first to sixth configurations, wherein a boundary line of a region to be processed has a fractal dimension of 1.1 to 1.6 dimensions.
[0052]
In general, the fractal dimension is an index indicating the complexity of a curve or the like, and by applying this value to the boundary line, it is possible to indicate how complicated the boundary line is, thereby knowing the degree of compounding. be able to.
[0053]
When the fractal dimension of the boundary line is less than 1.1, the respective regions are not sufficiently combined, and as a result, the interaction force of each region acts individually, and the interaction force is relatively low. In some cases, the suppression effect such as toner particle component fixation in a large region cannot be sustained for a long time. On the other hand, in the case where the fractal dimension exceeds 1.6, the complexity of the composite is too large, so that it is likely to exhibit substantially the same behavior as the single phase, and it is difficult to exert the effect of the composite.
[0054]
As an example of how to obtain the fractal dimension at the boundary line between the Amod region and other regions, the following method can be given.
First, an Amod region is specified from the area of each region of the SPM phase shift distribution image obtained by the method described above. Next, only the boundary portion of the Amod area is extracted by image processing. Further, the length of the boundary line is approximated using a straight line segment having the same length shorter than the entire length of the boundary line, and the length of the used line segment and the number of required line segments are obtained. Plot the logarithm of both and read the fractal dimension from the gradient.
[0055]
As another method for obtaining the fractal dimension, the correlation dimension calculation method can also be used. Specifically, first, only the boundary line part of the distribution image Amod area is extracted, and at all the points (total number = N) on the boundary line, the boundary line that is in the circle of radius r centered on each point. Count the number of points. The counts of all points are totaled, and a value obtained by dividing by the square of the total number N is defined as C (r). The same operation is performed by changing the radius r of the circle, the points (logr, logC (r)) are plotted, and the fractal dimension (correlation dimension) is read from the gradient.
[0056]
In order to easily configure the component of the region having a relatively weak interaction force and / or the region having the maximum occupied area and prevent the toner particle component from being fixed, it is preferable that these regions contain silicon atoms. That is, the eighth aspect of the present invention is the electrophotographic carrier according to any one of the first to seventh aspects, wherein the region occupied by Amin and / or Amod contains silicon atoms. is there.
[0057]
On the other hand, in order to form a region having a relatively strong interaction force and / or a region that takes up the maximum occupied area, and to easily charge the toner particles, these regions may contain nitrogen atoms. preferable. That is, the ninth aspect of the present invention is the electrophotographic carrier according to any one of the first to eighth aspects, wherein the region occupied by Amax and / or Amod contains a nitrogen atom. is there.
[0058]
Furthermore, according to the tenth aspect of the present invention, in any one of the first to ninth aspects, the region that occupies the surface of the carrier particle includes a siloxane bond. According to the eleventh aspect of the present invention, any one of the first to tenth aspects is characterized in that any region occupying the surface of the carrier particles includes a structure having a polysilazane skeleton. An electrophotographic carrier according to claim 1. In particular, the surface of the composite coating layer of the present invention can be made to have a high strength and toughness surface that is evenly uniform and microscopically highly composited by adopting these configurations.
[0059]
According to a twelfth aspect of the present invention, there is provided an electrophotographic developer comprising a mixture of electrophotographic carrier particles and toner particles containing at least a binder resin and a colorant, wherein the carrier particles comprise the first constitution to An electrophotographic developer, which is the electrophotographic carrier according to any one of the eleventh configurations.
[0060]
As the toner particles used in the present invention, those usually used as an electrophotographic toner can be used without any particular limitation.
For example, as an example of a binder resin used in the electrophotographic toner, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene and the like, and a substituted homopolymer thereof; styrene / p-chlorostyrene copolymer Polymer, styrene / propylene copolymer, styrene / vinyl toluene copolymer, styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer Styrene / octyl acrylate copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, Styrene / acrylonitrile copolymer, styrene / vinyl methyl keto Styrene copolymers such as copolymers, styrene / butadiene copolymers, styrene / isoprene copolymers, styrene / maleic acid copolymers; polymethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polymethacryl Acrylic acid ester homopolymers such as butyl acid and copolymers thereof; polyvinyl derivatives such as polyvinyl chloride and polyvinyl acetate; polyester polymers, polyurethane polymers, polyamide polymers, polyimide polymers, polyols Polymer, epoxy polymer, terpene polymer, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, etc., which can be used alone or in combination, but are not particularly limited thereto. . Among these, at least one selected from styrene-acrylic copolymer resins, polyester resins, and polyol resins is more preferable from the viewpoint of electrical characteristics, cost, and the like. Furthermore, it is more preferable to use a polyester-based resin and / or a polyol-based resin as having good fixing characteristics.
[0061]
As the colorant used in the electrophotographic toner, pigments and dyes conventionally used as toner colorants can be used. Specifically, carbon black, lamp black, iron black, ultramarine blue, Nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6C lake, chalcoil blue, chrome yellow, quinacridone red, benzidine yellow, rose bengal and the like can be used alone or in combination.
[0062]
Furthermore, if necessary, in order to give the toner particles magnetic properties, iron oxides such as ferrite, magnetite and maghematite, metals such as iron, cobalt and nickel, or alloys of these with other metals can be used. The components may be contained in the toner particles alone or in combination. Moreover, these components can also be used / used together as a colorant component.
[0063]
Furthermore, in order to use a so-called oil-less fixing method that does not use a release agent such as oil during toner fixing, it is realized by incorporating waxes such as polyethylene wax, propylene wax, carnauba wax in the toner particles. it can. The amount used is preferably about 0.5 to 10.0% by weight, more preferably about 3.0 to 8.0% by weight, although it depends on the type of material used and the fixing method. preferable.
[0064]
In addition, generally known charge control agents for improving the rising of charge can be used, such as amino group-containing vinyl copolymers, quaternary ammonium salt compounds, nigrosine dyes, polyamine resins, imidazoles. Positive charge control agents such as compounds, azine dyes, triphenylmethane dyes, guanidine compounds, lake pigments, and negative charge charges such as carboxylic acid derivatives and their metal salts, alkoxylates, organometallic complexes, chelate compounds The control agent can be used alone or mixed to form a kneaded product and / or additive into the toner particles. When these charge control agents are used in a dispersed state, the dispersion diameter is preferably 2.0 μm or less, and preferably 1.0 μm or less in order for the interaction with the carrier particle surface to occur substantially evenly. Further preferred.
[0065]
As additives for improving toner fluidity and environment dependency, generally known additives can be used. For example, zinc oxide, tin oxide, aluminum oxide, titanium oxide, silicon oxide, strontium titanate, barium titanate, titanium Inorganic powders such as calcium oxide, strontium zirconate, calcium zirconate, lanthanum titanate, calcium carbonate, magnesium carbonate, mica and dolomite, and hydrophobized products thereof can be used alone or in combination. As other additives, fluororesin fine particles such as polytetrafluoroethylene, tetrafluoroethylene hexafluoropropylene copolymer, and polyvinylidene fluoride may be used as the toner surface modifier. Depending on the type of material to be added, about 0.1 to 10 parts by weight is externally added to 100 parts by weight of the toner base particles, and if necessary, the toner is mixed with an appropriate mixer. It can be adjusted and used so that it adheres to, adheres to the particle surface, or is released in the toner particle gap.
[0066]
As a method for producing toner particles in the developer of the present invention, the raw materials as described above are kneaded by a known method such as a two-roll, twin-screw extrusion kneader, or single-screw extrusion kneader. The toner base particles can be prepared by performing known pulverization and classification such as an airflow method. Further, at the time of kneading, a colorant or a dispersant for controlling the dispersion state of the magnetic material may be used in combination. Further, the toner base particles may be mixed and surface-modified with a mixer or the like by adding the aforementioned additives.
[0067]
In addition, the charge amount of these toner particles varies depending on the actual use process and cannot be determined in general. However, in the combination with the carrier particles according to the configuration of the present invention, the absolute value is about 3 to 40 μC / g. The saturated charge amount is more preferably about 5 to 30 μC / g.
[0068]
Furthermore, the thirteenth aspect of the present invention is the electrophotographic developer according to the twelfth aspect, wherein the toner particle number-based 10% diameter is 2.5 μm or more.
As described above, the configuration of the present invention controls the contact / friction / peeling state of toner particles and carrier particles in and near the contact region. In the case where there are many toner particles that are too small to exceed the degree of surface complexation of the carrier particles of the present invention, these toner particles are attached to a region occupied by a composition having a relatively large interaction force. When used for a long time, it may appear as toner particle component fixation.
[0069]
Therefore, in the developer for electrophotography using carrier particles according to the structure of the present invention, it is preferable that the number of toner particles having such a small particle diameter is as small as possible. It is preferable that the number of 10% or less, that is, the number-based 10% diameter is 2.5 μm or more.
[0070]
The fourteenth aspect of the present invention is a developer container that is filled with the electrophotographic developer according to the twelfth or thirteenth aspect.
[0071]
Furthermore, the fifteenth aspect of the present invention is an image forming apparatus, wherein a container filled with the electrophotographic developer according to the fourteenth aspect is loaded.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
The image forming apparatus of the present invention will be described below with reference to the drawings.
FIG. 5 shows an example of an image forming apparatus on which a container filled with the electrophotographic developer of the present invention is mounted, and a developing section (1) mounted in the image forming apparatus main body, FIG. 3 is a partial cross-sectional view showing a developer container (2) filled with the electrophotographic developer of the present invention replenished in the developing section (1), and a developer feeding means (3) for connecting the two. .
[0073]
In FIG. 5, the developing section (1) includes a developing housing (4) filled with the electrophotographic developer of the present invention containing a liquid two-component developer (D) formed by mixing toner and carrier. And first and second stirring screws (5) and (6) for stirring and mixing the developer (D), and a developing roller (7). The developing roller (7) is a latent image. It is arranged to face the photosensitive member (8) as a carrier. The photoconductor (8) is rotationally driven in the direction indicated by the arrow, and an electrostatic latent image is formed on the surface thereof. In the figure, reference numeral (26) denotes a cap fitted on the connecting member (24) fixed to the developer receiving port (23) through or without the filter (25).
Around the photosensitive member (8), other well-known units such as a charging unit, an exposure unit, a transfer unit, a charge removing unit, and a cleaning unit (not shown) are arranged.
[0074]
As the first and second agitating screws (5) and (6) rotate, the developer (D) in the developing housing (4) is agitated, and the toner is triboelectrically charged with opposite polarity to the carrier. . The developer (D) is supplied to the peripheral surface of the developing roller (7) that is rotationally driven in the direction of the arrow, and the supplied developer is carried on the peripheral surface of the developing roller (7). It is conveyed in the rotation direction by the rotation of 7). Next, the amount of the conveyed developer is regulated by the doctor blade (9), and the regulated developer is conveyed to the development area between the photosensitive member (8) and the developing roller (7), where The toner in the developer is electrostatically transferred to the electrostatic latent image on the surface of the photoreceptor, and the electrostatic latent image is visualized as a toner image.
[0075]
Next, the carrier particle surface structure of the present invention will be described using schematic diagrams. First, FIG. 1 is an example of a conceptual diagram of a carrier particle surface composite state of the configuration of the present invention. In this case, regions having different interaction forces are divided into three locations. FIG. 2 is a phase shift amount in the XY portion of FIG. 1, and the magnitudes of Emax, Emin, and Eavg are also shown. However, Eavg is calculated on the basis of the occupied area of each region. In this example, the region 3 has the largest occupied area, and this region component is Amod. In this region range, a 2 μm straight line segment is not included only in a single region.
[0076]
FIG. 3 shows an example of a method for obtaining the fractal dimension according to the seventh configuration of the present invention. In this example, the curves from A to A 'are shown when the solid line segment is the unit length and when the broken line segment (1/2 of the solid line segment) is the unit length. The same segmentation is performed with line segments of various lengths, and the number of line segments used to segment line segment length (relative value when the distance of AA ′ is 1) and AA ′ is shown in a log-log graph. Then, FIG. 4 is obtained. From this gradient, the fractal dimension of the curve AA 'can be obtained.
[0077]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Here, “parts” are all parts by weight.
[0078]
Example 1
(Coating agent 1)
10 parts of dimethoxysilicone / polyethyleneimine composite resin
(Dimethoxysilicone / polyethyleneimine = 3/1)
100 parts of ethanol
[0079]
Using the coating agent 1 mixed in the above formulation, the amount of the layer thickness after drying becomes about 1 μm, coated and heat-dried from a fluidized bed spray coat at a coating temperature = 60 ° C., and further in an air atmosphere by an electric furnace. Carrier particles 1-2 were obtained by firing at 160 ° C. for 90 minutes to form a surface coat layer satisfying the surface properties of the present invention.
Here, as the core material particles, spherical ferrite particles having a weight average particle size of 50 μm were used.
[0080]
(Toner base particle composition)
79 parts of polyester resin
(Bisphenol A ethylene oxide addition alcohol,
Propylene oxide addition alcohol of bisphenol A,
Condensation polymer of terephthalic acid and trimellitic acid;
(Mw = about 12,000, glass transition point = about 60 ° C.)
Carbon black (Mitsubishi Carbon Corporation, # 44) 15 parts
Charge control agent (chromium-containing dye, Hodogaya Chemical Co., Ltd .;
AIZON SPILON BLACK TRH) 1 part
Carnauba wax (manufactured by Noda Wax) 5 parts
[0081]
The mixture having the above composition was kneaded for 30 minutes with a two-roll kneader and then pulverized and classified with a mechanical pulverizer / airflow classifier to obtain toner base particles.
Furthermore, 100 parts of the toner base particles are added with 1 part of hydrophobic silica fine particles whose surface is treated with dimethylsilane, and mixed for a total of 2 minutes using a Henschel mixer, and a test corresponding to each toner base particle. Toner particles 1 were obtained.
When the particle size distribution of the toner particles 1 was measured with a Coulter counter TA2, the weight average diameter D4 was 6.5 μm, and the number-based 10% diameter calculated from the cumulative number distribution was 2.8 μm.
[0082]
Evaluation values of the phase shift amount distribution of the carrier particles 1-2 are shown in Table 1-1 and Table 1-2.
[0083]
[Table 1-1]

[0084]
[Table 1-2]

[0085]
Here, the phase shift amount of the carrier particle surface coating layer was measured using a scanning probe microscope Nanoscope IIIa, Dimension 3100 and a phase detection extender module (PHASE-D01 type) manufactured by Digital Instruments.
Carrier particles as a measurement sample were fixed onto an aluminum flat plate with a thinly applied adhesive. The scanning range was 5 μm square, three independent points were measured for each sample, each value was calculated based on these distribution measurement data, and the average value was taken as the evaluation value.
Next, whether or not the Amod region and the region other than Amod cross the 2 μm line segment in each phase shift amount distribution measurement range was visually confirmed based on the phase shift amount distribution image.
Subsequently, for the boundary line between Amod and other regions, fractal dimensions were obtained from the logarithmic plot gradient of the line segment length vs. the number of line segments used, using five types of line segments having different unit lengths.
[0086]
Further, in order to evaluate the charge imparting characteristics of the carrier particles, the carrier particle 1-2 and the toner particles 1 were used, and a toner particle charge amount rising test by stirring was performed. The mixing ratio of carrier particles and toner particles was 95: 5 on a weight basis, and the stirring time was 10 seconds, 60 seconds, and 600 seconds. The toner charge amount was measured by a so-called blow-off method using an electrometer (610C; manufactured by Kesley) to measure the charge amount while separating toner particles and carrier particles by an air flow.
[0087]
Further, using these carrier particles and toner particles, a continuous image drawing test of 300,000 original sheets of A4 size, 6% image area ratio was performed using a modified machine of Ricoh copier imagio MF-6550. Character images and solid images after continuous drawing were output and image quality evaluation was performed. As the image quality evaluation, the background fogging in the character portion, the stability of the image density in the solid image, and the presence or absence of other defects in each image were evaluated. The image density was measured using a Macbeth densitometer (RD-914), and the other items were visually evaluated.
[0088]
The electrostatic charge image on the image carrier at the time of image output was set to background portion = −700V and image portion = −200V. A DC developing bias potential was applied to the developing sleeve.
Each developer after the end of the continuous image drawing test for 300,000 sheets is collected, toner particles adhering to the surface are removed by air blow, and a certain amount of the remaining carrier particles are dispersed in toluene to obtain a supernatant. The amount of the toner particle component fixed matter eluted was evaluated. For the evaluation of the amount of fixed matter, the difference between the white visible light transmittance and the white visible light transmittance of the test sample in the supernatant liquid collected by the same method using unused carrier particles as a contrast is calculated as the amount of the surface sticking component. Taking each as a difference, each sample was evaluated relative. The transmittance was measured using a spectrophotometer TC-1800 (manufactured by Tokyo Denshoku) and a C50 light source.
Similarly, the degree of abrasion of the carrier particle surface coating layer obtained from each developer after completion of the 300,000 continuous image drawing test was measured by elemental analysis using fluorescent X-rays. In the measurement, the core material without the coating layer, the carrier particles before the test and the carrier particles after the test were measured simultaneously, and the wear rate (%) of the coating layer was calculated from the X-ray intensity of the specific element.
[0089]
As a result of the above tests and evaluations, the carrier particles of Example 1 showed almost no change in charging performance after running, and the same image quality was obtained, and the coating layer was worn and the toner components adhered. It was confirmed that the amount of carrier particles was extremely small.
[0090]
The evaluation results at the initial stage and after 300,000 sheets are shown in Tables 3-1 and 3-2.
[0091]
Example 2
The surface properties of the present invention are satisfied in the same manner except that the firing conditions in the electric furnace are the firing temperature = 200 ° C. and the firing time = 30 minutes, the firing temperature is raised from Example 1 and the surface properties of the carrier particles are adjusted. Carrier particles 1-4 having a surface coat layer were obtained.
Carrier particle surface property evaluation, charge amount evaluation, and image evaluation were performed in the same manner as in Example 1 using carrier particles 1-4.
[0092]
The carrier particles of Example 2 are carrier particles with little change in charging performance as compared with the initial stage after running, equivalent image quality, and extremely low coat layer wear and toner component fixing amount. confirmed.
Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0093]
Example 3
(Coating agent 3)
Polysilazane 7 parts
Butyl methacrylate 3 parts
Carbon black 1 part
100 parts of toluene
[0094]
As another formulation example of the present invention, the coating agent 3 is used, the coating temperature = 90 ° C., the firing temperature = 200 ° C., the firing time = 30 minutes, and the carrier particle surface properties are adjusted by a coating agent formulation different from that in Example 1. Thus, carrier particles 3-1 having a surface coat layer satisfying the surface properties of the present invention were obtained.
The carrier particle surface property evaluation, charge amount evaluation, and image evaluation were performed in the same manner as in Example 1 except that the carrier particle 3-1 was used.
Even after running, the carrier particles of Example 3 have almost no change in charging performance as compared with the initial stage, can obtain the same image quality, and have very little coat layer wear and toner component fixing amount. confirmed.
Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0095]
Example 4
(Coating agent 4)
5 parts of polyimide
Acrylic resin 5 parts
Carbon black 1 part
100 parts of toluene
[0096]
As yet another formulation example of the present invention, the coating agent 4 is used, the coating temperature is 90 ° C., the firing temperature is 250 ° C., and the firing time is 90 minutes. Carrier particles 4-2 having a surface coat layer satisfying the surface properties were obtained.
The carrier particle surface property evaluation, the charge amount evaluation, and the image evaluation were performed in the same manner as in Example 1 except that the carrier particle 4-2 was used.
The carrier particles of Example 4 have almost no change in charging performance after running, the same image quality is obtained, the coat layer wear is extremely small, and the amount of toner component fixation is sufficiently small even after running. It was confirmed that.
Each evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0097]
Reference example 1
  The surface properties of the present invention are satisfied in the same manner except that the baking conditions are set to 120 ° C. and the baking time = 90 minutes, and the baking temperature is lowered from Example 1 to adjust the carrier particle surface properties. Carrier particles 1-1 having a surface coat layer were obtained.
  Using the carrier particles 1-1, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
  Reference example 1It was confirmed that the carrier particles of the present invention were the carrier particles with little change in charging performance compared with the initial stage even after running, the same image quality was obtained, and the coating layer wear and toner component fixing amount were extremely small. .
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0098]
Example5
(Coating agent 2)
    10 parts of dimethoxysilicone / polyethyleneimine composite resin
      (Dimethoxysilicone / polyethyleneimine = 1/3)
    100 parts of ethanol
[0099]
  As yet another formulation example of the present invention, a coating agent 2 having a different composite rate from the coating agent 1 is used, and the coating temperature is 60 ° C., the firing temperature is 160 ° C., and the firing time is 90 minutes. Thus, the carrier particle surface properties were adjusted to obtain carrier particles 2-2 having a surface coat layer satisfying the surface properties of the present invention.
  The carrier particle surface property evaluation, the charge amount evaluation, and the image evaluation were performed in the same manner as in Example 1 except that the carrier particle 2-2 was used.
  Example5The carrier particles of the present invention are carrier particles with little change in charging performance after running, almost the same image quality, sufficiently low wear of the coat layer, and a small amount of toner component fixation. confirmed.
  Each evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0100]
Example6
  The firing conditions in the electric furnace were set to firing temperature = 200 ° C. and firing time = 90 minutes.5Carrier particles 2-3 having a surface coat layer satisfying the surface properties of the present invention were obtained in the same manner except that the firing temperature was raised and the surface properties of the carrier particles were adjusted.
  Using the carrier particles 2-3, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
  Example6It was confirmed that the carrier particles of the present invention are carrier particles with little change in charging performance compared to the initial stage even after running, equivalent image quality, and sufficiently small coat layer wear and toner component fixation. It was.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0101]
Example7
  The firing conditions in the electric furnace were set to firing temperature = 160 ° C. and firing time = 180 minutes.5Carrier particles 2-4 having a surface coat layer satisfying the surface properties of the present invention were obtained in the same manner except that the surface properties of the carrier particles were adjusted by increasing the firing time.
  Using carrier particles 2-4, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
  Example7These carrier particles were confirmed to be carrier particles with little change in charging performance as compared with the initial stage after running, almost the same image quality, and less coating layer wear and toner component fixing amount.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0102]
Example8
  The surface properties of the present invention are satisfied in the same manner except that the firing conditions were set to be the firing temperature = 250 ° C., the firing time = 30 minutes, the firing temperature was raised from Example 3, and the carrier particle surface properties were adjusted. Carrier particles 3-2 having a surface coat layer were obtained.
  Carrier particle surface property evaluation, charge amount evaluation, and image evaluation similar to Example 1 were performed using the carrier particle 3-2.
  Example8It is confirmed that the carrier particles of this type are carrier particles that have a small change in charging performance compared with the initial stage even after running, can obtain the same image quality, have less coating layer wear, and have a sufficiently small amount of toner component fixation. It was done.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0103]
Example9
  The firing conditions in the electric furnace were set to firing temperature = 250 ° C. and firing time = 60 minutes.8The carrier particles 3-3 having a surface coat layer satisfying the surface properties of the present invention were obtained in the same manner except that the firing time was increased to adjust the surface properties of the carrier particles.
  Using the carrier particles 3-3, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
  Example9It was confirmed that the carrier particles of the present invention are carrier particles with little change in charging performance compared to the initial stage even after running, equivalent image quality, and sufficiently small coat layer wear and toner component fixation. It was.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0104]
Example10
  The surface property of the present invention is satisfied in the same manner except that the firing condition is set to 200 ° C. and the firing time is 90 minutes, the firing temperature is lowered from Example 4 and the carrier particle surface property is adjusted. Carrier particles 4-1 having a surface coat layer were obtained.
  Using the carrier particles 4-1, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as those in Example 1 were performed.
  Example10It is confirmed that the carrier particles of this type are carrier particles that have a small change in charging performance compared with the initial stage even after running, can obtain the same image quality, have less coating layer wear, and have a sufficiently small amount of toner component fixation. It was done.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0105]
Example11
  Satisfying the surface properties of the present invention in the same manner except that the firing conditions were set to firing temperature = 250 ° C., firing time = 240 minutes, the firing time was longer than in Example 4 and the carrier particle surface properties were adjusted. Carrier particles 4-3 having a surface coat layer to be obtained were obtained.
  Carrier particle surface property evaluation, charge amount evaluation, and image evaluation were performed in the same manner as in Example 1 using carrier particle 4-3.
  Example11It is confirmed that the carrier particles of the present invention are carrier particles with little change in charging performance compared to the initial stage after running, equivalent image quality, low coat layer wear, and extremely low toner component adhesion. It was done.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0106]
Comparative Example 1
The surface properties of the present invention were the same except that the carrier particle surface properties were adjusted by setting the firing conditions in the electric furnace to a firing temperature of 200 ° C. and a firing time of 90 minutes, and making the firing time longer than in Example 2. Carrier particles 1-3 having a surface coat layer deviating from the above were obtained.
Using the carrier particles 1-3, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
Even in the initial stage, the carrier particles of Comparative Example 1 had insufficient charging performance, and thus not only a lot of background fogging was observed, but also the wear of the coat layer in the running test was so severe that the carrier particles could not withstand practical use.
Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0107]
Comparative Example 2
  The firing conditions in the electric furnace were set to firing temperature = 120 ° C. and firing time = 90 minutes.5The carrier particles 2-1 having a surface coat layer deviating from the surface properties of the present invention were obtained in the same manner except that the surface properties of the carrier particles were adjusted by lowering the firing temperature.
  Using the carrier particles 2-1, the same carrier particle surface property evaluation, charge amount evaluation and image evaluation as in Example 1 were performed.
  The carrier particles of Comparative Example 2 have sufficient charging performance in the initial stage and good image quality can be obtained. However, the charging performance deteriorates as the toner component is fixed in the running test, and the running of 300,000 sheets is possible. However, the image quality was unbearable at all.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2.
[0108]
Comparative Example 3
(Coating agent 5)
10 parts acrylic resin
Carbon black 1 part
100 parts of toluene
[0109]
  As a formulation example that does not become a composite coat layer, the coating agent 5 excluding the composite part of the coating agent 4 was used, and the examples10Similarly, the carrier particle surface property is adjusted under the production conditions of coating temperature = 90 ° C., firing temperature = 200 ° C., firing time = 90 minutes, and the carrier has a surface coat layer deviating from the surface property of the present invention. Particle 5-1 was obtained.
  The carrier particle surface property evaluation, the charge amount evaluation, and the image evaluation were performed in the same manner as in Example 1 except that the carrier particle 5-1 was used.
  Since the carrier particles of Comparative Example 3 have insufficient charging performance even in the initial stage, they not only have a lot of background fogging, but the toner component is severely fixed by a running test, and the charging performance is further deteriorated. Was unbearable.
  Each measurement / evaluation result is shown in Table 1-1, Table 1-2, Table 3-1, and Table 3-2. Table 2 lists the correspondence between the carrier particles used and the examples and comparative examples.
[0110]
[Table 2]

[0111]
Example12-14
  Further, carrier particles 1-2 of Example 1, Example8Carrier particles 3-2, Examples7Toner particles 1 and 4 except that the toner base particle pulverization / classification conditions were changed to adjust the weight average diameter D4 = 6.3 μm and the number-based 10% diameter = 2.3 μm. When the same image evaluation as in each example was performed in combination with the toner particles 2 made in the same manner, even after running, an image quality having no practical problem was obtained.
  Each evaluation result is shown in Table 3-1 and Table 3-2.
[0112]
[Table 3-1]

  Background fogging ◎: Extremely excellent
                    ○: No problem in practical use
                    Δ: Acceptable level
                    N: Cannot be used
[0113]
[Table 3-2]

  Background fogging ◎: Extremely excellent
                    ○: No problem in practical use
                    Δ: Acceptable level
                    N: Cannot be used
[0114]
【The invention's effect】
As mentioned above, according to the structure of this invention, it is detailed and concrete including the comparison of the carrier particle characteristic value in Table 1-1, Table 1-2, and the Example and comparative example which are seen in Table 3-1, Table 3-2. As is clear from this explanation, the wear of the carrier particle surface coat layer and the adhesion of the toner particle components to the carrier particles are extremely small over a long period of time, resulting in a decrease in image density and image deterioration such as toner dust and background fogging. It is an excellent two-component developer for electrophotography and electrophotography that is extremely effective for obtaining high-quality images with high definition and high resolution, as well as the characteristics necessary to obtain stable images without any problems. There is an effect.
[Brief description of the drawings]
FIG. 1 is an example of a conceptual diagram of a carrier particle surface composite state according to the configuration of the present invention.
2 is a diagram showing a phase shift amount distribution (XY cross section) of the composite surface in FIG. 1; FIG.
FIG. 3 is a diagram illustrating an example of fractal dimension division of a boundary line according to the configuration of the present invention.
FIG. 4 is a diagram illustrating a fractal dimension calculation example.
FIG. 5 is a view showing a container filled with the electrophotographic developer of the present invention and an image forming apparatus equipped with the container.
[Explanation of symbols]
1 Development section
2 Developer container
3 Developer flow means
4 Development housing
5 Stir screw
6 Stir screw
7 Development roller
8 Photoconductor
9 Doctor blade
23 Developer inlet
24 connecting member
25 filters
26 cap
D Developer

Claims (12)

In an electrophotographic carrier in which a coating layer containing at least a resin phase is provided on the surface of a core material made of at least a magnetic material, the surface of the carrier particle is measured by phase transition measurement (Phase Imaging) in tapping mode scanning of a scanning probe microscope. Regions with different transition amounts are formed, the area of the component A (i) region occupying the carrier particle surface is S (i), and the phase shift amount in the component A (i) region is E (i) (i is 1 to 1). The number of regions having different phase shift amounts), the area area having a phase shift amount exceeding the phase shift occupied area reference average value Eavg = Σ (E (i) · S (i)) / ΣS (i) The ratio of the total sum S0 to S0 / ΣS (i) × 100 = 24 to 90%. (Σ represents total) 2. The electrophotographic carrier according to claim 1, wherein a ratio S0 / ΣS (i) × 100 = 24 to 75% of a total area S <b> 0 having a phase shift amount exceeding the Eavg is occupied. 2. The electrophotographic carrier according to claim 1, wherein a ratio S 0 / ΣS (i) × 100 = 24 to 50% of a total area S 0 having a phase shift amount exceeding the Eavg is occupied.   4. The area ratio Smin / ΣS (i) × 100 ≦ 80%, where Smin is an area occupied by the component Amin having the minimum phase shift amount Emin. Carrier for electrophotography.   5. The area ratio Smax / ΣS (i) × 100 ≦ 60%, wherein Smax is an area occupied by the component Amax having the maximum phase shift amount Emax. Carrier for electrophotography.   6. The electrophotographic carrier according to claim 1, wherein Emin and Emax satisfy a relational expression of 0.2 ≦ Emin / Emax ≦ 0.7.   The carrier for electrophotography according to any one of claims 1 to 6, wherein a silicon atom is contained in a region occupied by Amin and / or Amod.   The electrophotographic carrier according to any one of claims 1 to 7, wherein the region occupied by Amax and / or Amod contains a nitrogen atom.   9. The electrophotographic carrier according to claim 1, wherein any region occupying the surface of the carrier particle includes a siloxane bond.   The carrier for electrophotography according to any one of claims 1 to 9, wherein any region occupying the surface of the carrier particle includes a structure having a polysilazane skeleton.   11. The electrophotographic developer according to claim 1, wherein the carrier particle is an electrophotographic developer obtained by mixing electrophotographic carrier particles and toner particles containing at least a binder resin and a colorant. An electrophotographic developer which is a carrier.   12. The electrophotographic developer according to claim 11, wherein the toner particle has a number-based 10% diameter of 2.5 μm or more.

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