JP4115662B2 - Electrophotographic developer and image forming method - Google Patents

Description

」、（３）「該トナー中の添加微粒子の、トナー母体粒子に対する割合が、０．５〜５重量％であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真用現像剤」、（４）「トナー中４．０μｍ以下のトナー粒子が、５０個数％以下であることを特徴とする前記第（１）項乃至第（３）項の何れか１に記載の電子写真用現像剤」、（５）「像担持体上に形成された静電潜像をトナーおよびキャリア粒子よりなる電子写真用現像剤によって現像する画像形成方法であって、電子写真用現像剤が前記第（１）項乃至第（４）項のいずれか１に記載の電子写真用現像剤であることを特徴とする画像形成方法」、（６）「像担持体をクリーニング工程にてクリーニングし、クリーニング工程により回収したトナーを現像工程にて再使用することを特徴とする前記第（５）項記載の画像形成方法。
【００２０】
また、上記課題は本発明の（５）「前記第（１）項乃至第（４）項のいずれか１に記載の電子写真用現像剤を充填したことを特徴とする現像剤容器」により解決される。
【００２１】
また、上記課題は本発明の（６）「像担持体上に形成された静電潜像をトナーおよびキャリア粒子よりなる電子写真用現像剤によって現像する画像形成方法であって、電子写真用現像剤が前記第（１）項乃至第（４）項のいずれか１に記載の電子写真用現像剤であることを特徴とする画像形成方法」、（７）「像担持体をクリーニング工程にてクリーニングし、クリーニング工程により回収したトナーを現像工程にて再使用することを特徴とする前記第（６）項記載の画像形成方法」により解決される。
【００２２】
また、上記課題は本発明の（８）「像担持体上に形成された静電潜像をトナーおよびキャリア粒子よりなる電子写真用現像剤によって現像する画像形成手段を有する画像形成装置であって、電子写真用現像剤が前記第（１）項乃至第（４）項のいずれか１に記載の電子写真用現像剤であることを特徴とする画像形成装置」、（９）「静電潜像を現像する現像手段と、現像剤を前記現像手段に回収するクリーニング手段とを具備することを特徴とする前記第（８）項記載の画像形成装置」、（１０）「前記第（５）項に記載の電子写真用現像剤を充填した容器を装着したことを特徴とする前記第（８）項又は第（９）項に記載の画像形成装置」により解決される。
【００２３】
トナー中への添加微粒子およびキャリア粒子表面構成を、前記第（１）項に記載のものとすることにより、該現像剤は、極めて良好な現像剤特性の経時安定性を示すようになる。
【００２４】
すなわち、本発明の表面構成を持つキャリア粒子は、その表面の微細凹凸スケールが添加微粒子スケール以下であるため、添加微粒子が一旦キャリア粒子表面に移行したとしても、一定箇所に留まることなく速やかに転動する。これにより、トナー添加微粒子のキャリア粒子表面への固着は極めて少なくなり、表面形状制御をされていないキャリア粒子と比較して、長期に渡りキャリア粒子表面の変化を抑制することができ、安定した現像剤特性を発現させることができる。
【００２５】
キャリア粒子表面の大部分を占める、凹凸部の高低差が、５ｎｍを上回るときには、該キャリア粒子表面の微細凹凸スケールは、添加微粒子スケールと同程度となるため、遊離した添加微粒子が多く存在した状態で、トナー流動性を付与しているような場合には、添加微粒子が、キャリア粒子表面の微細凹部にはまり込んで脱離できなくなり、この影響によりキャリア粒子表面特性を変化させてしまう。更には、この部分が核となり更にトナー組成成分の固着を増加させる。
【００２６】
該微細凹凸部の高低差が５ｎｍ以下の領域は、キャリア粒子表面の６０％以上を占める。これより少ない占有領域の場合には、規定範囲外の領域に対する添加微粒子の固着によるキャリア粒子表面特性変動の影響が大きくなり、実質上、添加微粒子固着抑制による特性安定化効果を発揮させることは困難である。また、キャリア粒子表面内の該領域の割合は、７０％以上であることが、より好ましいものである。
【００２７】
ここで、キャリア粒子表面の微細構造は、概略以下のようにして、知ることができる。
まず、表面コート層を設けたキャリア粒子を、十分に剛性の高い支持体に固定する。このとき、固定には、必要に応じて両面テープや接着剤等を用いても良い。次に、粒子を固定した試料を、室温・常圧の環境下で、走査型プローブ顕微鏡（ＳＰＭ）の測定部位にセットする。引き続き、測定部位を０．５〜１０μｍ程度のスキャン範囲で、測定プローブを共鳴周波数で振動させつつ試料表面を走査する、いわゆるタッピングモード走査を行なう。このとき、プローブ先端の曲率半径は５〜２０ｎｍ程度、タッピング周波数は１５０〜４５０ｋＨｚ程度が好ましく用いられる。上記条件により、タッピングモード走査を行なうことにより、微細な表面形状を観測することができる。
【００２８】
本発明の現像剤中のキャリア粒子構成は、前記第（１）項記載の構成範囲を取り得る限り、材料を限定するものではなく、従来公知のものが使用でき、例えば、キャリア粒子のコア材に使用できる無機／金属の磁性粒子の例としては、鉄、コバルト、ニッケル等の金属；マグネタイト、ヘマタイト、フェライトなどの合金や化合物等が挙げられるが、これらに限定されるものではない。これら磁性粒子は、単結晶／アモルファスの粒子、単独／複合の焼結体、単独／複合の粒子を樹脂等の高分子中に分散させた粒子等の、いずれのコア材形態で使用しても良い。また、磁性粒子を高分子中に分散させた粒子で、キャリア粒子の磁気特性と磁性粒子の分散性を両立させるには、これらの磁性粒子は０．５〜１０μｍ程度の大きさの粒子を含むことが好ましい。
【００２９】
次に、キャリア粒子のコア材粒子及び／又は表面コート層を形成する樹脂としては、例えばポリエチレン、ポリプロピレン、塩素化ポリエチレン、クロロスルホン化ポリエチレン等のポリオレフィン系樹脂；ポリスチレン、アクリル（例えばポリメチルメタクリレート）、ポリアクリロニトリル、ポリビニルアセテート、ポリビニルアルコール、ポリビニルブチラール、ポリ塩化ビニル、ポリビニルカルバゾール、ポリビニルエーテル、ポリビリケトン等のポリビニル及びポリビニリデン系樹脂；塩化ビニル−酢酸ビニル共重合体；オルガノシロキサン結合からなるシリコーン樹脂またはその変成品（例えばアルキッド樹脂、ポリエステル樹脂、エポキシ樹脂、ポリウレタン等による変成品）；ペルヒドロポリシラザンまたはその変性品（部分酸化品を含む）；ポリテトラフルオロエチレン、ポリ弗化ビニル、ポリ弗化ビニリデン、ポリクロロトリフルオロエチレン等の弗素樹脂；ポリアミド；ポリエステル；ポリウレタン；ポリカーボネート；ユリア樹脂；メラミン樹脂；ベンゾグアナミン樹脂；エポキシ樹脂等が挙げられる。中でも本発明の構成要件を満たすために好ましいコート層材料としては、シリコーン樹脂またはその変成品、弗素樹脂、特にシリコーン樹脂またはその変成品がより好ましい。
【００３０】
シリコーン樹脂としては、従来から知られているいずれのシリコーン樹脂であってもよく、下記式で示されるオルガノシロキサン結合のみからなるストレートシリコーンおよびアルキド、ポリエステル、エポキシ、ウレタンなどで変成したシリコーン樹脂が挙げられる。
【００３１】
【化１】

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のアリケニル基、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】
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。
【００３５】
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。これらの低抵抗微粉末は、キャリア粒子表面の微細凹凸の形成を抑制するためにも、コート層表面部分にはできる限り露出していないことが好ましい。
【００３６】
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。これらカップリング剤の使用は、前述の低抵抗微粉末の表面露出抑制に対しても有効である。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。
【００３７】
【化３】

但し、Ｘ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。
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。
【００３８】
コート層の形成法としては、従来と同様、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。
被覆層の厚さは０．１〜２０μmが好ましい。
【００３９】
一方、本発明の現像剤に使用するトナー構成についても同様に、前記第（１）項に記載の構成範囲を取り得る限り、材料を限定するものではなく、通常、電子写真用トナーとして使用される材料を、特に制限無く、使用することができる。
【００４０】
例えば、該電子写真用トナー母体粒子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。
【００４１】
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。
【００４２】
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。
【００４３】
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。
【００４４】
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。
【００４５】
トナー母体粒子同士の合一化を抑制しつつ、トナー流動性を向上させ、また環境依存性を安定化する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。
【００４６】
本発明の現像剤中のトナー製造方法としては、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、前述の微粒子を添加し、混合機等により混合・表面改質が行なわれる。
【００４７】
また、これらトナーの帯電電荷量は、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３〜８０μＣ／ｇ程度の飽和電荷量であることが好ましく、更には５〜５０μＣ／ｇ程度の飽和電荷量であることがより好ましく、１０〜４０μＣ／ｇ程度の飽和電荷量であることがいっそう好ましい。
【００４８】
次に、前記第（２）項記載のように、該キャリア粒子表面の１００ｎｍ×１００ｎｍ領域内の表面粗さＲｚと、該トナー中の添加微粒子の平均一次粒子径Ｄは、（式１）の関係であることが好ましく、両者の大小関係が（式１）を逸脱するような場合には、該領域のキャリア粒子表面での添加微粒子の転動が生じにくくなり、現像剤の撹拌条件によっては、添加微粒子固着の発生を十分に抑制できないことがあるため、好ましくない。
【００４９】
【数３】

【００５０】
一方、前記第（３）項記載のように、キャリア粒子表面コート層に、主鎖および／または側鎖にシロキサン結合骨格を持つ化合物を含有することにより、その表面エネルギーの小ささとあいまって、該キャリア粒子表面への添加微粒子固定化の抑制は、より確実なものとなる。
【００５１】
トナー母体粒子に対する外添微粒子の割合については、添加する材料の種類にもよるが、およそ０．５〜５重量％であることが好ましい。また、これらの添加微粒子は、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、少量のトナー粒子間隙での遊離状態になるよう調整し、用いることができる。
【００５２】
添加微粒子の添加量が、０．５重量％を下回る場合には、トナー母体粒子表面の添加微粒子による被覆が不十分となり、トナー母体粒子同士の合一化が発生することがあり、また、添加微粒子の添加量が、５重量％を上回る場合には、トナー母体粒子から遊離した添加微粒子が多く発生しやすく、遊離微粒子量の経時変化が大きくなることがあり、これにより生じるトナー自体の特性変動を、現像剤として十分に吸収できない場合が有る。添加微粒子の割合としては、トナー母体粒子に対して０．７〜３重量％程度であれば、更に好ましいものである。
【００５３】
また更に、本発明の現像剤に用いるトナー中に、あまりにも多くの微細なトナー粒子が含まれるような場合には、該微細トナー粒子自体が、キャリア粒子表面上へ付着しキャリア粒子表面を変質させることがあるため、好ましくない。
【００５４】
このような影響は、粒子径が小さな粒子に特有であり、特に４．０μｍ程度の大きさを持つ微粒子の量を制限することにより、更に現像剤を安定して長寿命化することができる。
【００５５】
したがって、本発明の構成による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、４．０μｍ以下の微小なトナー粒子が５０個数％以下であることが好ましく、３５個数％以下であることがより好ましい。
【００５６】
また、前記第（７）項として、像担持体上に形成された静電潜像をトナーおよびキャリア粒子よりなる電子写真用現像剤によって現像する画像形成方法において、電子写真用現像剤を前記第（１）項乃至第（５）項のいずれかに記載の電子写真用現像剤とすることにより、長期間にわたって安定した高品質の画像が得られる画像形成方法を提供でき、前記第（８）項として、更に、像担持体をクリーニング工程にてクリーニングし、クリーニング工程により回収したトナーを現像工程にて再使用することにより、上記の高品質画像を省資源で得るための画像形成方法を提供することができる。
【００５７】
また、前記第（９）項として、像担持体上に形成された静電潜像をトナーおよびキャリア粒子よりなる電子写真用現像剤によって現像する画像形成手段を有する画像形成装置において、電子写真用現像剤を前記第（１）項乃至第（５）項のいずれかに記載の電子写真用現像剤とすることにより、上記の高品質画像を省資源で得るための画像形成装置を提供することができる。
【００５８】
また、前記第（１０）項として静電潜像を現像する現像手段と、現像剤を前記現像手段に回収するクリーニング手段とを具備する前記第（９）項に記載の画像形成装置とすることにより、上記の高品質画像を省資源で得るための画像形成装置を提供することができる。
【００５９】
また、前記第（１１）項として、前記第（１）項乃至第（５）項のいずれかに記載の電子写真用現像剤を充填した容器を装着した画像形成装置とすることにより、上記の高品質画像を省資源で得るための画像形成装置を提供することができる。
【００６０】
【発明の実施の形態】
以下に図を用いて、本発明の画像形成方法について説明を加える。まず、図１は画像形成装置の一例の断面図である。ドラム状の像担持体（１）の周囲に、像担持体帯電部材（２）、像露光系（３）、現像機構（４）、転写機構（５）、クリーニング機構（６）、除電ランプ（７）が配置されていて、以下の動作で画像形成を行なう。
【００６１】
画像形成の一連のプロセスは、ネガ−ポジプロセスで説明を行なう。有機光導電層を有する感光体（ＯＰＣ）に代表される像担持体（１）は除電ランプ（７）で除電され、帯電チャージャーや帯電ローラーといった帯電部材（２）で均一にマイナスに帯電され、レーザー光学系（３）より照射されるレーザー光で潜像形成（露光部電位の絶対値は、非露光部電位の絶対値より低電位となる）が行なわれる。
【００６２】
レーザー光は半導体レーザーから発せられて、高速で回転する多角柱の多面鏡（ポリゴン）等により像担持体（１）の表面を像担持体（１）の回転軸方向に走査する。このようにして形成された潜像が、現像機構（４）にある現像剤担持体である現像スリーブ（４１）上に供給されたトナー粒子及びキャリア粒子の混合物からなる二成分現像剤により現像され、トナー可視像が形成される。潜像の現像時には、電圧印加機構（図示せず）から現像スリーブ（４１）に、像担持体（１）の露光部と非露光部の間にある、適当な大きさの電圧またはこれに交流電圧を重畳した現像バイアスが印加される。
【００６３】
一方、転写媒体（例えば紙）（９）が、給紙機構（図示せず）から給送され、上下一対のレジストローラー（図示せず）で画像先端と同期をとって像担持体（１）と転写部材（５１）との間に給送され、トナー像が転写される。このとき転写部材（５１）には、転写バイアスとして、トナー帯電の極性と逆極性の電位が印加されることが好ましい。その後転写媒体（９）は像担持体（１）より分離された後、定着装置（８）を経て出力画像として排出される。
【００６４】
また、像担持体上に残存するトナー粒子は、クリーニング部材（６１）にて、クリーニング機構（６）内のトナー回収室（６２）へ回収される。
回収されたトナー粒子は、トナーリサイクル手段（図示せず）により現像部および／またはトナー補給部に搬送され、再使用されても良い。
【００６５】
図２は、画像形成装置の現像装置主要部の概略構成図である。潜像担持体である感光体ドラム（１２）の側方に配設された現像機構（４）は、現像剤担持体としての現像スリーブ（４１）、現像剤収容部材（４２）、規制部材としてのドクターブレード（４３）、支持ケース（４４）等から主に構成されている。
【００６６】
感光体ドラム（１２）側に開口を有する支持ケース（４４）には、内部にトナー（１０）を収容するトナー収容部としてのトナーホッパー（４５）が接合されている。トナーホッパー（４５）に隣接した、トナー（１０）とキャリア粒子とからなる現像剤（１１）を収容する現像剤収容部（４６）には、トナー粒子（１０）とキャリア粒子を撹拌し、トナー粒子に摩擦／剥離電荷を付与するための、現像剤撹拌機構（４７）が設けられている。
【００６７】
トナーホッパー（４５）の内部には、図示しない駆動手段によって回動されるトナー供給手段としてのトナーアジテータ（４８）及びトナー補給機構（４９）が配設されている。トナーアジテータ（４８）及びトナー補給機構（４９）は、トナーホッパー（４５）内のトナー（１０）を現像剤収容部（４６）に向けて撹拌しながら送り出す。
【００６８】
感光体ドラム（１２）とトナーホッパー（４５）との間の空間には、現像スリーブ（４１）が配設されている。図示しない駆動手段で図の矢印方向に回転駆動される現像スリーブ（４１）は、キャリア粒子による磁気ブラシを形成するために、その内部に現像機構（４）に対して相対位置不変に配設された、磁界発生手段としての図示しない磁石を有する。
【００６９】
現像剤収容部材（４２）の、支持ケース（４４）に取り付けられた側と対向する側には、規制部材（ドクターブレード）（４３）が一体的に取り付けられている。規制部材（ドクターブレード）（４３）は、その先端と現像スリーブ（４１）の外周面との間に一定の隙間を保った状態で配設されている。
【００７０】
上記構成により、トナーホッパー（４５）の内部からトナーアジテータ（４８）、トナー補給機構（４９）によって送り出されたトナー（１０）は、現像剤収容部（４６）へ運ばれ、現像剤撹拌機構（４７）で撹拌されることによって、所望の摩擦／剥離電荷が付与され、キャリア粒子と共に現像剤（１１）として、現像スリーブ（４１）に担持されて感光体ドラム（１２）の外周面と対向する位置まで搬送され、トナー（１０）のみが感光体ドラム（１２）上に形成された静電潜像と静電的に結合することにより、感光体ドラム（１２）上にトナー像が形成される。
【００７１】
また、図２に記載の画像形成装置に代えて図３に示される画像形成装置を使用することができる。
図３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（７１）と、この現像部（７１）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（７２）と、この両者を接続する現像剤送流手段（７３）を示す部分断面図である。
【００７２】
図３において、現像部（７１）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（７４）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（７５）、（７６）と、現像ローラ（７７）とを有していて、当該現像ローラ（７７）が、潜像担持体の感光体（７８）に対向して配置されている。感光体（７８）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（８６）は、現像剤受入口（８３）に固定された接続部材（８４）の上にフィルター（８５）を介して又は介さず嵌合されたキャップである。
感光体（７８）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。
【００７３】
第１及び第２の攪拌スクリュー（７５）、（７６）が回転することにより、現像ハウジング（７４）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（７７）の周面に供給され、その供給された現像剤は現像ローラ（７７）の周面に担持され、当該現像ローラ（７７）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（７９）によって量を規制され、規制後の現像剤が感光体（７８）と現像ローラ（７７）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。
【００７４】
【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。
［実施例１］
（キャリア粒子製造例１）
ポリエチレンイミン／シリコーン樹脂（＝５０／５０）グラフト重合体溶液
（固形分＝１０％相当） ５００部
テトラエトキシシラン ２５部
エチルアルコール ４７５部
処方を撹拌機で撹拌してコート層形成用の塗工液を調整した。
これを重量平均粒径５０μｍの球形フェライト粒子５０００部の表面へ流動床型スプレーコート装置によりコート後、１６０℃／２時間加熱して各樹脂相組成を反応させ、表面にコート層を持つ、キャリア粒子（Ｃ１）を得た。
【００７５】
ここで、キャリア粒子表面コート層の形状観測は、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を用いて行なった。
【００７６】
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５００ｎｍ四方とし、各サンプルについて独立した３箇所を観測して、これらの表面形状観測データを元にキャリア粒子表面の微細凹凸部の高低差が５ｎｍ以下に相当する領域の占める割合およびスキャンプロフィールから１００ｎｍ×１００ｎｍ領域の表面粗さ（Ｒｚ）を算出した。
キャリア粒子表面観測結果を表１に示す。
【００７７】
【表１】

【００７８】
（トナー製造例１）
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＝１２０００、ガラス転移点＝６１℃）
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
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・分級条件を調整し、トナー母体粒子１を得た。
【００７９】
更に、該トナー母体粒子１に対して、１．０重量％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（平均一次粒子径＝２５ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ１）を得た。
トナー（Ｔ１）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＝６．０μｍであり、４．０μｍ以下のトナー粒子は４５個数％であった。
【００８０】
更に、このキャリア粒子（Ｃ１）１０００部及びトナー（Ｔ１）５０部を混合して、電子写真用現像剤を調整し、リコー製複写機imagio ＭＦ−６５５０の改造機を用い、トナーリサイクルを行ないつつ、Ａ４版、画像面積率６％原稿６０万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。
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。
６０万枚の連続画像出図試験終了後の現像剤を採取し、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電荷付与能力を、初期の現像剤における電荷付与能力と比較評価した。電荷量の測定は、通常のブローオフ法により行ない、トナーには、連続画像出図試験で用いたトナーと同じものを使用した。
初期及び６０万枚後の、各評価結果について、表２−１、２−２に示す。
【００８１】
［実施例２］
（キャリア粒子製造例２）
ポリエチレンイミン／シリコーン樹脂（＝５０／５０）グラフト重合体溶液
（固形分＝１０％相当） ５００部
テトラエトキシシラン ５０部
エチルアルコール ４５０部
コート層形成用の塗工液として上記処方を用いた以外はキャリア粒子製造例１と同様にしてキャリア粒子（Ｃ２）を得た。
キャリア粒子（Ｃ２）を用いた以外は、実施例１と同様；トナー（Ｔ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８２】
［実施例３］
（トナー製造例２）
トナー製造例１と同様にして得られた、トナー母体粒子１に対して、１．０重量％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（平均一次粒子径＝１５ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ２）を得た。
トナー（Ｔ２）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８３】
［実施例４］
（トナー製造例３）
トナー製造例１のトナー処方を用い、粉砕・分級条件を調整して、４．０μ以下のトナー粒子を多く含むトナー母体粒子２を得た。
更に、該トナー母体粒子２に対して、２．０重量％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（平均一次粒子径＝５０ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ３）を得た。
トナー（Ｔ３）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＝５．８μｍであり、４．０μｍ以下のトナー粒子は６０個数％であった。
トナー（Ｔ３）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８４】
［実施例５］
（トナー製造例４）
トナー製造例１と同様にして得られた、トナー母体粒子１に対して、０．４重量％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（平均一次粒子径＝２５ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ４）を得た。
トナー（Ｔ４）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８５】
［実施例６］
（トナー製造例５）
トナー製造例１と同様にして得られた、トナー母体粒子１に対して、５．５重量％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（平均一次粒子径＝２５ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ５）を得た。
トナー（Ｔ５）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８６】
［実施例７］
（トナー製造例６）
トナー製造例３と同様にして得られた、トナー母体粒子２に対して、５．５重量％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（平均一次粒子径＝２５ｎｍ）を加えて、ヘンシェルミキサーにより、トータル２分間混合しトナー（Ｔ６）を得た。
トナー（Ｔ６）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８７】
［実施例８］
（キャリア粒子製造例３）
重量平均粒径５０μｍの球形フェライト粒子５０００部およびポリエチレンパウダー５０部をバッチ式混合機に投入し、９０±１０℃に加熱しつつ２時間せん断混合後、室温にて放冷し、ポリエチレン皮膜で表面改質したキャリア粒子（Ｃ３）を得た。
キャリア粒子（Ｃ３）を用いた以外は、実施例１と同様；トナー（Ｔ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８８】
［実施例９］
キャリア粒子として（Ｃ２）を用い、トナーとして（Ｔ２）を用いた以外は、実施例１と同様にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００８９】
［実施例１０］
キャリア粒子として（Ｃ３）を用い、トナーとして（Ｔ６）を用いた以外は、実施例１と同様にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００９０】
［比較例１］
ポリエチレンイミン／シリコーン樹脂（＝５０／５０）グラフト重合体溶液
（固形分＝１０％相当） ５００部
テトラエトキシシラン １００部
エチルアルコール ４００部
コート層形成用の塗工液として上記処方を用いた以外はキャリア粒子製造例１と同様にしてキャリア粒子（Ｃ４）を得た。
キャリア粒子（Ｃ４）を用いた以外は、実施例１と同様；トナー（Ｔ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００９１】
［比較例２］
（トナー製造例７）
トナー母体粒子に添加する微粒子として、ジメチルシラン処理した疎水性シリカ微粒子（平均一次粒子径＝４ｎｍ）を用い、トナー母体粒子に対する微粒子添加の割合を、１．０重量％とした以外は、トナー製造例１と同様にして、トナー（Ｔ７）を得た。
トナー（Ｔ７）を用いた以外は、実施例１と同様；キャリア粒子（Ｃ１）；にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００９２】
［比較例３］
（トナー製造例８）
トナー母体粒子に添加する微粒子として、ジメチルシラン処理した疎水性シリカ微粒子（平均一次粒子径＝２２０ｎｍ）を用い、トナー母体粒子に対する微粒子添加の割合を、２．０重量％とした以外は、トナー製造例１と同様にして、トナー（Ｔ８）を得た。
トナー（Ｔ８）を用いた以外は、実施例１と同様にして、各評価結果を得た。評価結果を、表２−１、表２−２に示す。
【００９３】
最後に、実施例１の現像剤について、引き続き、１００万枚連続画像出図試験を行なったところ、初期画像と比較して全く遜色のない高精細・高解像度の画像が得られた。
【００９４】
【表２−１】

【００９５】
【表２−２】

【００９６】
【発明の効果】
以上、詳細且つ具体的な説明から、本発明の構成によれば、表１におけるキャリア粒子表面形状とトナー中への添加微粒子一次粒子径の関係及び、表２に見られる実施例および比較例の対比から明らかなように、現像剤の劣化による、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非常に長期間に渡って得るのに、極めて有効な電子写真用二成分現像剤であり、同時に、省資源に対しても有効な、電子写真用二成分現像剤および画像形成方法であった。
【図面の簡単な説明】
【図１】本発明に用いられる画像形成装置の一例の断面図である。
【図２】本発明に用いられる画像形成装置の現像装置主要部の概略構成図である。
【図３】本発明に用いられる画像形成装置の現像装置主要部の他の概略構成図である。
【符合の説明】
１ 像担持体
２ 帯電部材
３ 像露光系
４ 現像機構
５ 転写機構
６ クリーニング機構
７ 除電ランプ
８ 定着装置
９ 転写媒体
１０ トナー
１１ 現像剤
１２ 感光体ドラム
４１ 現像スリーブ
４２ 現像剤収容部材
４３ 規制部材（ドクターブレード）
４４ 支持ケース
４５ トナーホッパー
４６ 現像剤収容部
４７ 現像剤撹拌機構
４８ トナーアジテーター
４９ トナー補給機構
５１ 転写部材
５２ 除電ブラシ
６１ クリーニング部材
６２ トナー回収室
７１ 現像部
７２ 現像剤収納容器
７３ 現像剤送流手段
７４ 現像ハウジング
７５ 攪拌スクリュー
７６ 攪拌スクリュー
７７ 現像ローラ
７８ 感光体
７９ ドクターブレード
８３ 現像剤受入口
８４ 接続部材
８５ フィルター
８６ キャップ
Ｄ 現像剤[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called carrier particle that is a charge imparting member that imparts a charge to toner particles by stirring with the toner particles, a two-component developer containing at least the toner particles, and an image forming method using the same. In particular, the present invention relates to an image forming method having a so-called recycling mechanism in which toner remaining on an image carrier is reused in development, and an electrophotographic developer suitable for this.
[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]
Furthermore, with the recent trend of energy saving, the fixing energy of toner in image formation has decreased, and for this reason, a resin that softens with a lower thermal energy than before has tended to be adopted as a binder resin for toner. is there. These resins tend to have high adhesiveness even at room temperature. For this reason, to ensure toner fluidity by preventing toner particles from binding at room temperature, and to fix the toner base particle composition component to the carrier particle surface. In order to prevent (so-called toner spent), it tends to contain a large amount of externally added fine particles as a fluidity improver. However, in such a toner, although the adhesion of the toner base particle composition component to the carrier particle surface is suppressed, a part of the externally added fine particles contained in the toner tend to be in a free state. In some cases, the carrier particles adhere strongly to the surface of the carrier particles due to the action of an external force such as agitation, and cause fluctuations in developer properties such as fluctuations in charge imparting ability of carrier particles.
[0007]
On the other hand, from the viewpoint of resource saving, a toner recycling process for reusing the so-called transfer residual toner remaining on the image carrier after transferring the toner from the image carrier to an image transfer medium such as paper Including image forming methods are becoming common. In the image forming method including such a toner recycling step, the externally added fine particles in the toner may be embedded in the toner base particles in the toner recycling step. In order to suppress the fluctuation in toner fluidity associated with this, a larger amount of externally added fine particles are used, and as a result, the amount of free externally added fine particles in the toner increases. In the case of the developer, the change in the developer characteristics with time was more prominent.
[0008]
When the developer characteristics fluctuate, deterioration in image quality such as a decrease in image density, occurrence of background fogging, a decrease in resolving power, etc. appears as a change with time, and further, physical / electrical properties of the image carrier. Deterioration of the image forming system such as generation of scratches and contamination of the charging member may be caused, and the life of the image forming apparatus itself is shortened.
[0009]
Therefore, in order to obtain a stable and good quality image over a long period of time and further to maintain the life of the image forming apparatus, the characteristics of the developer should be stable without changing depending on the period of use. It has become important, and various proposals have been made so far focusing on the suppression of variation over time.
[0010]
As an example of these, in JP-A-6-43686, a carrier having a concavo-convex structure on the surface and a carrier having a concavo-convex structure on the surface are used at the same time, so that the rising of charging is improved while preventing toner spent; In Japanese Laid-Open Patent Application No. 8-190224, a magnetic carrier having a central particle size of 60 to 100 μm having fine irregularities on the surface and a spherical toner having a central particle size of 5 to 8 μm are used to increase the carrier surface area. The toner can be charged even if it adheres to the surface; Japanese Patent Application Laid-Open No. 9-244301 discloses that the average sphericity is 1.1 or more and 1.5 or less and the sphericity is less than 1.3. By having 70% by number or more, carrier surface unevenness to the extent that it appears in sphericity is suppressed, and spent toner fine powder is prevented.
[0011]
However, since these proposals focus on the fixing of the toner base composition component to the carrier particle surface, a longer life of the developer is required and resource saving is achieved. In addition, an electrophotographic developer and an image forming method that prevent the addition of the added fine particles in the toner to the surface of the carrier particles and have sufficiently stable developer characteristics have not been studied at all.
[0012]
As described above, in the two-component developer, a proposal for suppressing a change in developer characteristics for a long period of time, in particular, a proposal for suppressing immobilization of the additive fine particles in the toner on the surface of the carrier particles has not been made yet. It has been a very difficult task to stably obtain a high-quality image without changing the developer.
[0013]
[Problems to be solved by the invention]
In view of the current problems as described above, the present invention suppresses a change in developer characteristics with time so that it can be substantially ignored, and can retain a high-quality image for an extremely long time, and can be fixed with a lower fixing energy. An object of the present invention is to provide a very high-performance electrophotographic developer capable of maintaining a high-quality image even for a toner capable of energy-saving fixing.
Another object of the present invention is to provide an image forming method capable of substantially reducing waste toner and having an extremely small influence on the natural environment.
[0014]
[Means for Solving the Problems]
In order to suppress fluctuations in developer characteristics, it is important to suppress changes over time in the surface characteristics of carrier particles as a frictional charge imparting member, and in particular, it is particularly important to suppress fluctuations in charge imparting characteristics on the surface of carrier particles. It is.
[0015]
The variation in the charge imparting characteristics on the surface of the carrier particles is largely caused by the toner composition components moving to and fixed on the surface of the carrier particles due to the impact force during agitation and friction with the toner, thereby contaminating the surface of the carrier particles. Therefore, by suppressing the occurrence of such a phenomenon, the variation in charge imparting characteristics of the carrier particles can be extremely reduced.
[0016]
In addition, as described above, the fluctuation of the charge imparting characteristics over time is not affected by the fixing of the toner base particle component, but the toner and the carrier particle surface due to the migration / fixation of the externally added fine particles onto the carrier particle surface. The effect of homogenization is extremely large. In other words, it is possible to minimize the migration of additive fine particles contained in the toner to the surface of the carrier particles as much as possible while maintaining sufficient toner fluidity and maintaining rapid diffusion of the replenishment toner into the developer. It is important for the suppression.
[0017]
As a result of diligent research, the present inventors have found that there are fine irregularities on the surface of the carrier particles and the primary particle size range of the added fine particles contained in the toner that can significantly suppress the adhesion of the added fine particles to the surface of the carrier particles. By specifying these states and ranges, it was confirmed that the initial developer characteristics can be maintained for a very long time while maintaining the toner fluidity, and the present invention has been completed.
[0018]
  That is, the above-mentioned problem is (1) “electrophotographic developer obtained by mixing toner obtained by externally adding fine particles to toner base particles comprising at least a colorant and a binder resin, and carrier particles for electrophotography. In
  The average primary particle size of the additive fine particles in the toner is 5 to 200 nm,
  The carrier particles are electrophotographic carrier particles in which a coating layer containing a resin phase is provided on the surface of a core material made of at least a magnetic material,
The coating layer is a coating layer formed using a graft polymer containing at least a silicone resin and tetraethoxysilane, and is a scanning probe microscope manufactured by Digital Instruments. NanoscopeIIIa, Dimension3100 With the measurement atThe surface of the carrier particles has irregularities, and the region where the height difference between an arbitrary convex portion and a concave portion adjacent thereto is 5 nm or less occupies 60% or more of the surface of the carrier particles. “Developer”, (2) “Surface roughness Rz in the region of 100 nm × 100 nm of the surface of the carrier particles and the average primary particle diameter D of the added fine particles in the toner are in the relationship of (Formula 1). The electrophotographic developer according to item (1).
[0019]
[Expression 2]

"(3)“The ratio of the added fine particles in the toner to the toner base particles is 0.5 to 5% by weight,” (1)Or item (2)The developer for electrophotography described in ","(4)“The toner particles having a particle size of 4.0 μm or less in the toner are 50% by number or less.(3)The electrophotographic developer according to any one of the items "(5)“An image forming method for developing an electrostatic latent image formed on an image bearing member with an electrophotographic developer comprising toner and carrier particles, wherein the electrophotographic developer comprises the above-mentioned items (1) to (1).(4)An image forming method, which is the electrophotographic developer according to any one of items 1 to 3,(6)“The image bearing member is cleaned in a cleaning step, and the toner collected in the cleaning step is reused in a developing step.(5)The image forming method according to Item.
[0020]
  In addition, the above problem is(5)“Items (1) to (1)(4)This can be solved by a developer container filled with the electrophotographic developer according to any one of the items.
[0021]
  In addition, the above problem is(6)“An image forming method for developing an electrostatic latent image formed on an image bearing member with an electrophotographic developer comprising toner and carrier particles, wherein the electrophotographic developer comprises the above-mentioned items (1) to (1).(4)An image forming method, which is the electrophotographic developer according to any one of items 1 to 3,(7)“The image bearing member is cleaned in a cleaning step, and the toner collected in the cleaning step is reused in a developing step.(6)This is solved by the “image forming method”.
[0022]
  In addition, the above problem is(8)“An image forming apparatus having an image forming means for developing an electrostatic latent image formed on an image bearing member with an electrophotographic developer comprising toner and carrier particles, wherein the electrophotographic developer is the first (1). ) To No.(4)An image forming apparatus, which is the electrophotographic developer according to any one of items 1 to 3,(9)“The developing means for developing the electrostatic latent image and the cleaning means for collecting the developer in the developing means”(8)Image forming apparatus according to item ",(10)"The first(5)A container filled with the electrophotographic developer described in the above item.(8)Term or number(9)The image forming apparatus described in the above item is solved.
[0023]
When the fine particles added to the toner and the surface structure of the carrier particles are those described in the above item (1), the developer exhibits extremely good developer characteristics over time.
[0024]
That is, the carrier particles having the surface configuration of the present invention have a fine unevenness scale on the surface thereof that is equal to or smaller than the additive fine particle scale, so even if the additive fine particles once move to the surface of the carrier particle, the carrier particles are quickly transferred without staying at a certain place. Move. As a result, adhesion of the toner-added fine particles to the surface of the carrier particles is extremely reduced, and it is possible to suppress changes in the surface of the carrier particles over a long period of time compared to carrier particles whose surface shape is not controlled. Agent characteristics can be developed.
[0025]
When the height difference of the concavo-convex portion occupying most of the carrier particle surface exceeds 5 nm, the fine concavo-convex scale on the surface of the carrier particle is almost the same as the additive fine particle scale, so that a large amount of free additive fine particles are present. In the case where toner fluidity is imparted, the added fine particles get stuck in the fine recesses on the surface of the carrier particles and cannot be detached, and this influence changes the carrier particle surface characteristics. Further, this portion serves as a nucleus and further increases the adhesion of the toner composition components.
[0026]
The region where the height difference of the fine irregularities is 5 nm or less occupies 60% or more of the carrier particle surface. If the area is smaller than this, the influence of the carrier particle surface fluctuation due to the adhesion of the added fine particles to the area outside the specified range becomes large, and it is practically difficult to exert the characteristic stabilization effect by suppressing the adhesion of the added fine particles. It is. The ratio of the region in the carrier particle surface is more preferably 70% or more.
[0027]
Here, the fine structure of the carrier particle surface 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 in a measurement site of a scanning probe microscope (SPM) under an environment of room temperature and normal pressure. Subsequently, so-called tapping mode scanning is performed in which the measurement surface is scanned within a scan range of about 0.5 to 10 μm while the measurement probe is vibrated at the resonance frequency and the sample surface is scanned. 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. By performing tapping mode scanning under the above conditions, a fine surface shape can be observed.
[0028]
The carrier particle constitution in the developer of the present invention is not limited as long as the constitutional range described in the above item (1) can be taken, and conventionally known ones can be used. For example, the carrier particle core material Examples of inorganic / metal magnetic particles that can be used in the present invention include, but are not limited to, metals such as iron, cobalt, and nickel; alloys and compounds such as magnetite, hematite, and ferrite. 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. Among them, as a preferable coating layer material for satisfying the constituent requirements of the present invention, a silicone resin or a modified product thereof, a fluorine resin, particularly a silicone resin or a modified product thereof is more preferable.
[0030]
The silicone resin may be any conventionally known silicone resin, and includes straight silicone consisting only of an organosiloxane bond represented by the following formula and a silicone resin modified with alkyd, polyester, epoxy, urethane or the like. It is done.
[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]
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.
[0035]
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, and more preferably 5 to 5 parts by weight. 20 parts by weight is preferred. These low resistance fine powders are preferably not exposed as much as possible on the surface of the coat layer in order to suppress the formation of fine irregularities on the surface of the carrier particles.
[0036]
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. Use of these coupling agents is also effective for suppressing surface exposure of the above-mentioned low resistance fine powder. Examples of the silane coupling agent used in the present invention include compounds represented by the following general formula.
[0037]
[Chemical Formula 3]

X is a hydrolyzable group bonded to a silicon atom and includes a chloro group, an alkoxy group, an acetoxy group, an alkylamino group, a propenoxy group, and the like.
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.
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.
[0038]
As a method for forming the coating layer, a coating layer forming liquid may be applied to the surface of the core material particles by means of a spraying method, a dipping method, or the like, as in the past.
The thickness of the coating layer is preferably from 0.1 to 20 μm.
[0039]
On the other hand, the toner composition used in the developer of the present invention is not limited as long as the composition range described in the above item (1) can be taken, and is generally used as an electrophotographic toner. The material to be used can be used without particular limitation.
[0040]
For example, as an example of the binder resin used for the toner base particles for electrophotography, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, and the like, and a homopolymer of the substitution product; styrene / p-chlorostyrene Copolymer, 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 Polymer, styrene / acrylonitrile copolymer, styrene / vinyl methacrylate Styrene copolymers such as ketone ketone, styrene / butadiene copolymer, styrene / isoprene copolymer, styrene / maleic acid copolymer; polymethyl acrylate, polybutyl acrylate, polymethyl methacrylate, poly Acrylic acid ester-based homopolymers such as butyl methacrylate and copolymers thereof; polyvinyl derivatives such as polyvinyl chloride and polyvinyl acetate; polyester-based polymers, polyurethane-based polymers, polyamide-based polymers, polyimide-based polymers, Examples include polyol polymers, epoxy polymers, terpene polymers, aliphatic or alicyclic hydrocarbon resins, and aromatic petroleum resins, which can be used alone or in combination, but are not limited to these. Absent. Of these, at least one selected from styrene-acrylic copolymer resins, polyester resins, and polyol resins is more preferable in terms 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.
[0041]
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, calco oil blue, chrome yellow, quinacridone red, benzidine yellow, rose bengal and the like can be used alone or in combination.
[0042]
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.
[0043]
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.
[0044]
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.
[0045]
Generally known additives can be used as additives for improving toner fluidity and stabilizing environmental dependency while suppressing coalescence of toner base particles, such as zinc oxide and tin oxide. , Aluminum oxide, titanium oxide, silicon oxide, strontium titanate, barium titanate, calcium titanate, strontium zirconate, calcium zirconate, lanthanum titanate, calcium carbonate, magnesium carbonate, mica, dolomite Can be used alone or in admixture. As other additives, fluororesin fine particles such as polytetrafluoroethylene, tetrafluoroethylene hexafluoropropylene copolymer, and polyvinylidene fluoride may be used as the toner surface modifier.
[0046]
As a method for producing the toner 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, and this is mechanically or air-flowed. The toner base particles can be prepared by performing known pulverization and classification such as a formula. 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 are added with the above-mentioned fine particles, and are mixed and surface-modified by a mixer or the like.
[0047]
In addition, the charge amount of these toners 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 saturation value is approximately 3 to 80 μC / g in absolute value. The charge amount is preferably, more preferably about 5 to 50 μC / g, more preferably about 10 to 40 μC / g.
[0048]
Next, as described in the above item (2), the surface roughness Rz in the region of 100 nm × 100 nm of the surface of the carrier particles and the average primary particle diameter D of the added fine particles in the toner are It is preferable that the relationship between the two deviates from (Equation 1), and it becomes difficult for the added fine particles to roll on the surface of the carrier particles in the region, and depending on the stirring conditions of the developer This is not preferable because the occurrence of the adhesion of the added fine particles may not be sufficiently suppressed.
[0049]
[Equation 3]

[0050]
On the other hand, as described in the item (3), the carrier particle surface coat layer contains a compound having a siloxane bond skeleton in the main chain and / or side chain, combined with the small surface energy, Suppression of immobilization of the added fine particles on the surface of the carrier particles becomes more reliable.
[0051]
The ratio of the externally added fine particles to the toner base particles is preferably about 0.5 to 5% by weight although it depends on the kind of the material to be added. Further, these additive fine particles can be mixed and mixed by an appropriate mixer so that they are adhered and adhered to the surface of the toner particles, or adjusted to be in a free state with a small amount of toner particle gaps.
[0052]
When the added amount of the added fine particles is less than 0.5% by weight, the surface of the toner base particles may be insufficiently coated with the added fine particles, and the toner base particles may be coalesced. When the added amount of fine particles exceeds 5% by weight, a large amount of added fine particles released from the toner base particles are likely to be generated, and the change in the amount of free fine particles with time may increase, resulting in fluctuations in the characteristics of the toner itself. May not be sufficiently absorbed as a developer. The ratio of the added fine particles is more preferably about 0.7 to 3% by weight with respect to the toner base particles.
[0053]
Furthermore, when the toner used in the developer of the present invention contains too many fine toner particles, the fine toner particles themselves adhere to the surface of the carrier particles and change the surface of the carrier particles. This is not preferable because it may cause
[0054]
Such an effect is peculiar to particles having a small particle diameter. In particular, by limiting the amount of fine particles having a size of about 4.0 μm, the developer can be further extended in life.
[0055]
Accordingly, in the electrophotographic developer according to the configuration of the present invention, it is preferable that the number of toner particles having such a small particle size is as small as possible. Specifically, the number of fine toner particles of 4.0 μm or less is 50% by number or less. It is preferable that it is 35% by number or less.
[0056]
In the image forming method of developing the electrostatic latent image formed on the image carrier with an electrophotographic developer comprising toner and carrier particles, the electrophotographic developer is used as the item (7). By using the electrophotographic developer according to any one of items (1) to (5), an image forming method capable of obtaining a stable and high-quality image over a long period of time can be provided. In addition, an image forming method for obtaining the above-mentioned high-quality image with resource saving by further cleaning the image carrier in the cleaning process and reusing the toner collected in the cleaning process in the developing process is provided. can do.
[0057]
In addition, as the item (9), in an image forming apparatus having an image forming means for developing an electrostatic latent image formed on an image carrier with an electrophotographic developer comprising toner and carrier particles, By providing the developer for electrophotography according to any one of (1) to (5) as a developer, an image forming apparatus for obtaining the high-quality image with resource saving is provided. Can do.
[0058]
The image forming apparatus according to item (9), further comprising: a developing unit that develops the electrostatic latent image as the item (10); and a cleaning unit that collects the developer in the developing unit. Thus, it is possible to provide an image forming apparatus for obtaining the above-described high-quality image with resource saving.
[0059]
Further, as the item (11), an image forming apparatus equipped with a container filled with the electrophotographic developer according to any one of items (1) to (5) is used. It is possible to provide an image forming apparatus for obtaining a high-quality image with resource saving.
[0060]
DETAILED DESCRIPTION OF THE INVENTION
The image forming method of the present invention will be described below with reference to the drawings. First, FIG. 1 is a cross-sectional view of an example of an image forming apparatus. Around the drum-shaped image carrier (1), an image carrier charging member (2), an image exposure system (3), a developing mechanism (4), a transfer mechanism (5), a cleaning mechanism (6), a static elimination lamp ( 7) is arranged, and image formation is performed by the following operation.
[0061]
A series of image forming processes will be described as a negative-positive process. The image carrier (1) typified by a photoreceptor (OPC) having an organic photoconductive layer is neutralized by a static elimination lamp (7), and is uniformly negatively charged by a charging member (2) such as a charging charger or a charging roller, A latent image is formed by the laser light emitted from the laser optical system (3) (the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential).
[0062]
Laser light is emitted from a semiconductor laser, and the surface of the image carrier (1) is scanned in the direction of the rotation axis of the image carrier (1) by a polygonal polygon mirror (polygon) that rotates at high speed. The latent image formed in this way is developed with a two-component developer comprising a mixture of toner particles and carrier particles supplied on a developing sleeve (41) which is a developer carrying member in the developing mechanism (4). A toner visible image is formed. At the time of developing the latent image, a voltage of an appropriate magnitude between the exposed portion and the non-exposed portion of the image carrier (1) or AC is applied to the developing sleeve (41) from a voltage application mechanism (not shown). A developing bias with a superimposed voltage is applied.
[0063]
On the other hand, a transfer medium (for example, paper) (9) is fed from a paper feed mechanism (not shown), and is synchronized with the leading edge of the image by a pair of upper and lower registration rollers (not shown). And the transfer member (51) to transfer the toner image. At this time, it is preferable that a potential opposite to the polarity of toner charging is applied to the transfer member (51) as a transfer bias. Thereafter, the transfer medium (9) is separated from the image carrier (1) and then discharged as an output image through the fixing device (8).
[0064]
The toner particles remaining on the image carrier are collected by the cleaning member (61) into the toner collection chamber (62) in the cleaning mechanism (6).
The collected toner particles may be transported to a developing unit and / or a toner replenishing unit by a toner recycling unit (not shown) and reused.
[0065]
FIG. 2 is a schematic configuration diagram of a main part of the developing device of the image forming apparatus. The developing mechanism (4) disposed on the side of the photosensitive drum (12) as a latent image carrier has a developing sleeve (41) as a developer carrier, a developer accommodating member (42), and a regulating member. The doctor blade (43), the support case (44), and the like.
[0066]
To a support case (44) having an opening on the photosensitive drum (12) side, a toner hopper (45) as a toner containing portion for containing toner (10) is joined. In the developer accommodating portion (46) that accommodates the developer (11) composed of toner (10) and carrier particles adjacent to the toner hopper (45), the toner particles (10) and carrier particles are agitated. A developer stirring mechanism (47) is provided for imparting friction / release charges to the particles.
[0067]
Inside the toner hopper (45), a toner agitator (48) and a toner replenishing mechanism (49) are disposed as toner supplying means rotated by a driving means (not shown). The toner agitator (48) and the toner replenishing mechanism (49) send out the toner (10) in the toner hopper (45) toward the developer container (46) while stirring.
[0068]
A developing sleeve (41) is disposed in the space between the photosensitive drum (12) and the toner hopper (45). The developing sleeve (41) that is rotationally driven in the direction of the arrow in the figure by a driving means (not shown) is disposed in the interior thereof so as not to change relative position with respect to the developing mechanism (4) in order to form a magnetic brush made of carrier particles. In addition, it has a magnet (not shown) as magnetic field generating means.
[0069]
A regulating member (doctor blade) (43) is integrally attached to the side of the developer accommodating member (42) facing the side attached to the support case (44). The restricting member (doctor blade) (43) is disposed in a state where a certain gap is maintained between the tip thereof and the outer peripheral surface of the developing sleeve (41).
[0070]
With the above configuration, the toner (10) sent out from the inside of the toner hopper (45) by the toner agitator (48) and the toner replenishing mechanism (49) is carried to the developer accommodating portion (46), and the developer agitating mechanism ( 47), the desired friction / peeling charge is imparted, and the carrier particles and the developer (11) are carried on the developing sleeve (41) and face the outer peripheral surface of the photosensitive drum (12). The toner image is conveyed to the position, and only the toner (10) is electrostatically coupled with the electrostatic latent image formed on the photosensitive drum (12), whereby a toner image is formed on the photosensitive drum (12). .
[0071]
Further, the image forming apparatus shown in FIG. 3 can be used instead of the image forming apparatus shown in FIG.
FIG. 3 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 unit (71) mounted in the image forming apparatus main body, FIG. 6 is a partial cross-sectional view showing a developer container (72) filled with the electrophotographic developer of the present invention to be replenished in the developing section (71) and a developer flow means (73) for connecting the two. .
[0072]
In FIG. 3, the developing section (71) includes a developing housing (74) 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 (75) and (76) for stirring and mixing the developer (D), and a developing roller (77). The developing roller (77) is a latent image. It is arranged to face the photosensitive member (78) of the carrier. The photoreceptor (78) 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 (86) denotes a cap fitted on the connecting member (84) fixed to the developer receiving port (83) through or without the filter (85).
Around the photoreceptor (78), other known units such as a charging unit, an exposure unit, a transfer unit, a charge eliminating unit, and a cleaning unit (not shown) are arranged.
[0073]
The developer (D) in the developing housing (74) is agitated by the rotation of the first and second agitating screws (75) and (76), and the toner is triboelectrically charged to the opposite polarity. . The developer (D) is supplied to the peripheral surface of the developing roller (77) that is rotationally driven in the direction of the arrow, and the supplied developer is carried on the peripheral surface of the developing roller (77), and the developing roller (77) 77), the sheet is conveyed in the rotation direction. Next, the amount of the conveyed developer is regulated by the doctor blade (79), and the regulated developer is conveyed to a development area between the photosensitive member (78) and the developing roller (77), 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.
[0074]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example. Here, “parts” are all parts by weight.
[Example 1]
(Carrier particle production example 1)
Polyethyleneimine / silicone resin (= 50/50) graft polymer solution
(Solid content = 10% equivalent) 500 parts
25 parts of tetraethoxysilane
475 parts of ethyl alcohol
The formulation was stirred with a stirrer to prepare a coating solution for forming a coat layer.
A carrier having a coating layer on the surface by coating the surface of 5000 parts of spherical ferrite particles having a weight average particle size of 50 μm with a fluidized bed type spray coater and then heating at 160 ° C./2 hours to react each resin phase composition. Particles (C1) were obtained.
[0075]
Here, the shape of the carrier particle surface coating layer was observed using a scanning probe microscope Nanoscope IIIa, Dimension 3100 manufactured by Digital Instruments.
[0076]
Carrier particles as a measurement sample were fixed onto an aluminum flat plate with a thinly applied adhesive. The scanning range is 500 nm square, and three independent points are observed for each sample. Based on these surface shape observation data, the ratio of the area corresponding to the difference in height of the fine irregularities on the surface of the carrier particles to 5 nm or less and the scan The surface roughness (Rz) in the 100 nm × 100 nm region was calculated from the profile.
Table 1 shows the observation results of the carrier particle surface.
[0077]
[Table 1]

[0078]
(Toner Production Example 1)
79 parts of polyester resin
(Bisphenol A ethylene oxide addition alcohol,
Propylene oxide addition alcohol of bisphenol A,
Terephthalic acid, trimellitic acid condensation polymer,
(Mw = 12000, glass transition point = 61 ° C.)
Carbon black; Mitsubishi Carbon # 44 15 parts
Charge control agent; chromium metal-containing dye; made by Hodogaya Chemical Co., Ltd.
AIZON SPILON BLACK TRH 1 part
Carnauba wax; Noda Wax 5 parts
The mixture having the above composition was kneaded for 30 minutes with a two-roll kneader, and then pulverized and classified using a mechanical pulverizer / airflow classifier to obtain toner base particles 1.
[0079]
Further, 1.0% by weight of hydrophobic silica fine particles (average primary particle size = 25 nm) whose surface is treated with dimethylsilane is added to the toner base particles 1 and mixed for a total of 2 minutes by a Henschel mixer. Toner (T1) was obtained.
When the particle size distribution of the toner (T1) was measured with a Coulter counter TA2, the weight average diameter D4 was 6.0 μm, and the number of toner particles of 4.0 μm or less was 45% by number.
[0080]
Further, 1000 parts of the carrier particles (C1) and 50 parts of the toner (T1) are mixed to prepare an electrophotographic developer, and toner recycling is performed using a modified machine of the Ricoh copier imagio MF-6550. , A4 size, 6% image area ratio 600,000 continuous image drawing test was performed, and the initial and post-printing character images and solid images were output to evaluate the image quality. 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.
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.
The developer after the continuous image drawing test of 600,000 sheets was collected, the toner particles adhering to the surface were removed by air blow, and the charge imparting ability of the remaining carrier particles was applied to the initial developer. It was compared with ability. The charge amount was measured by a normal blow-off method, and the same toner as that used in the continuous image drawing test was used.
The evaluation results at the initial stage and after 600,000 sheets are shown in Tables 2-1 and 2-2.
[0081]
[Example 2]
(Carrier particle production example 2)
Polyethyleneimine / silicone resin (= 50/50) graft polymer solution
(Solid content = 10% equivalent) 500 parts
50 parts of tetraethoxysilane
450 parts of ethyl alcohol
Carrier particles (C2) were obtained in the same manner as in Carrier Particle Production Example 1 except that the above formulation was used as the coating liquid for forming the coat layer.
Each evaluation result was obtained in the same manner as in Example 1 except that the carrier particles (C2) were used; Toner (T1). The evaluation results are shown in Tables 2-1 and 2-2.
[0082]
[Example 3]
(Toner Production Example 2)
To toner base particles 1 obtained in the same manner as in Toner Production Example 1, 1.0% by weight of hydrophobic silica fine particles (average primary particle size = 15 nm) whose surface was treated with dimethylsilane were added. The toner (T2) was obtained by mixing for a total of 2 minutes using a Henschel mixer.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T2) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0083]
[Example 4]
(Toner Production Example 3)
Using the toner formulation of Toner Production Example 1, the pulverization / classification conditions were adjusted to obtain toner base particles 2 containing a large amount of toner particles of 4.0 μm or less.
Further, hydrophobic silica fine particles (average primary particle size = 50 nm) whose surface is treated with dimethylsilane at a ratio of 2.0% by weight are added to the toner base particles 2 and mixed for a total of 2 minutes by a Henschel mixer. Toner (T3) was obtained.
When the particle size distribution of the toner (T3) was measured with a Coulter counter TA2, the weight average diameter D4 was 5.8 μm, and the number of toner particles of 4.0 μm or less was 60% by number.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T3) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0084]
[Example 5]
(Toner Production Example 4)
To toner base particles 1 obtained in the same manner as in Toner Production Example 1, hydrophobic silica fine particles (average primary particle size = 25 nm) whose surface was treated with dimethylsilane at a ratio of 0.4% by weight were added. The toner (T4) was obtained by mixing for a total of 2 minutes with a Henschel mixer.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T4) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0085]
[Example 6]
(Toner Production Example 5)
Hydrophobic silica fine particles (average primary particle size = 25 nm) whose surface was treated with dimethylsilane at a ratio of 5.5% by weight to toner base particles 1 obtained in the same manner as in Toner Production Example 1, The toner (T5) was obtained by mixing for a total of 2 minutes using a Henschel mixer.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T5) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0086]
[Example 7]
(Toner Production Example 6)
Hydrophobic silica fine particles (average primary particle size = 25 nm) whose surface was treated with dimethylsilane at a ratio of 5.5% by weight to toner base particles 2 obtained in the same manner as in Toner Production Example 3, The toner (T6) was obtained by mixing for a total of 2 minutes with a Henschel mixer.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T6) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0087]
[Example 8]
(Carrier particle production example 3)
5,000 parts of spherical ferrite particles having a weight average particle diameter of 50 μm and 50 parts of polyethylene powder are put into a batch mixer, shear mixed for 2 hours while heating to 90 ± 10 ° C., and then allowed to cool at room temperature. Modified carrier particles (C3) were obtained.
Each evaluation result was obtained in the same manner as in Example 1 except that carrier particles (C3) were used; Toner (T1); The evaluation results are shown in Tables 2-1 and 2-2.
[0088]
[Example 9]
Each evaluation result was obtained in the same manner as in Example 1 except that (C2) was used as carrier particles and (T2) was used as toner. The evaluation results are shown in Tables 2-1 and 2-2.
[0089]
[Example 10]
Each evaluation result was obtained in the same manner as in Example 1 except that (C3) was used as carrier particles and (T6) was used as toner. The evaluation results are shown in Tables 2-1 and 2-2.
[0090]
[Comparative Example 1]
Polyethyleneimine / silicone resin (= 50/50) graft polymer solution
(Solid content = 10% equivalent) 500 parts
100 parts of tetraethoxysilane
400 parts of ethyl alcohol
Carrier particles (C4) were obtained in the same manner as in Carrier Particle Production Example 1 except that the above formulation was used as a coating liquid for forming a coat layer.
Each evaluation result was obtained in the same manner as in Example 1 except that the carrier particles (C4) were used; toner (T1). The evaluation results are shown in Tables 2-1 and 2-2.
[0091]
[Comparative Example 2]
(Toner Production Example 7)
Toner production except that dimethylsilane-treated hydrophobic silica fine particles (average primary particle size = 4 nm) were used as fine particles to be added to the toner base particles, and the proportion of fine particles added to the toner base particles was 1.0% by weight. In the same manner as in Example 1, a toner (T7) was obtained.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T7) was used; carrier particles (C1). The evaluation results are shown in Tables 2-1 and 2-2.
[0092]
[Comparative Example 3]
(Toner Production Example 8)
Toner production except that dimethylsilane-treated hydrophobic silica fine particles (average primary particle size = 220 nm) were used as fine particles to be added to the toner base particles, and the ratio of the fine particle addition to the toner base particles was 2.0% by weight. In the same manner as in Example 1, a toner (T8) was obtained.
Each evaluation result was obtained in the same manner as in Example 1 except that the toner (T8) was used. The evaluation results are shown in Tables 2-1 and 2-2.
[0093]
Finally, the developer of Example 1 was subjected to a continuous image drawing test of 1 million sheets. As a result, a high-definition and high-resolution image completely comparable to the initial image was obtained.
[0094]
[Table 2-1]

[0095]
[Table 2-2]

[0096]
【The invention's effect】
As described above, from the detailed and specific description, according to the configuration of the present invention, the relationship between the carrier particle surface shape in Table 1 and the primary particle diameter of the added fine particles in the toner, and the examples and comparative examples shown in Table 2 are shown. As is clear from the comparison, it has the characteristics necessary to obtain a stable image without image deterioration such as toner density and background fog due to developer deterioration, and at the same time, high definition and high resolution. It is a two-component developer for electrophotography that is extremely effective for obtaining quality images over a very long period of time, and at the same time, is a two-component developer for electrophotography and an image forming method effective for resource saving. there were.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of an image forming apparatus used in the present invention.
FIG. 2 is a schematic configuration diagram of a main part of a developing device of an image forming apparatus used in the present invention.
FIG. 3 is another schematic configuration diagram of the main part of the developing device of the image forming apparatus used in the present invention.
[Explanation of sign]
1 Image carrier
2 Charging member
3 Image exposure system
4 Development mechanism
5 Transcription mechanism
6 Cleaning mechanism
7 Static elimination lamp
8 Fixing device
9 Transfer media
10 Toner
11 Developer
12 Photosensitive drum
41 Development sleeve
42 Developer accommodating member
43 Restriction member (doctor blade)
44 Support case
45 Toner Hopper
46 Developer container
47 Developer stirring mechanism
48 Toner Agitator
49 Toner supply mechanism
51 Transfer member
52 Static elimination brush
61 Cleaning member
62 Toner recovery chamber
71 Developer
72 Developer container
73 Developer delivery means
74 Developer housing
75 stirring screw
76 Stir screw
77 Development roller
78 photoconductor
79 Doctor Blade
83 Developer inlet
84 Connection member
85 filters
86 cap
D Developer

Claims (6)

In an electrophotographic developer formed by mixing toner obtained by externally adding fine particles to toner base particles composed of at least a colorant and a binder resin, and carrier particles for electrophotography.
The average primary particle size of the additive fine particles in the toner is 5 to 200 nm,
The carrier particles are electrophotographic carrier particles in which a coating layer containing a resin phase is provided on the surface of a core material made of at least a magnetic material,
The coating layer is a coating layer formed using a graft polymer containing at least a silicone resin and tetraethoxysilane, and is measured on the surface of the carrier particle by measurement with a scanning probe microscope Nanoscope IIIa, Dimension 3100 manufactured by Digital Instruments. An electrophotographic developer characterized in that a region having irregularities and a height difference between an arbitrary convex portion and a concave portion adjacent thereto is 5 nm or less occupies 60% or more of the surface of the carrier particles. 2. The electron according to claim 1, wherein the surface roughness Rz in the region of 100 nm × 100 nm of the surface of the carrier particles and the average primary particle diameter D of the added fine particles in the toner are in the relationship of (Equation 1). Photographic developer.

3. The electrophotographic developer according to claim 1, wherein the ratio of the additive fine particles in the toner to the toner base particles is 0.5 to 5 wt%. The following toner particles in the toner 4.0μm is, an electrophotographic developer according to any one of claims 1 to 3, characterized in that 50% by number or less. An image forming method for developing an electrostatic latent image formed on an image carrier with an electrophotographic developer comprising toner and carrier particles, wherein the electrophotographic developer is defined in any one of claims 1 to 4. An image forming method, which is the electrophotographic developer described above. 6. The image forming method according to claim 5, wherein the image bearing member is cleaned in the cleaning step, and the toner collected in the cleaning step is reused in the developing step.

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