JP3913064B2 - Image forming method - Google Patents

Description

【００５９】
ここで、「粒子投影面積」とは二値化された現像剤粒子像の面積であり、「粒子投影像の周囲長」とは該現像剤粒子像のエッジ点を結んで得られる輪郭線の長さと定義する。
【００６０】
本発明における円形度は現像剤粒子の凹凸の度合いを示す指標であり、現像剤粒子が完全な球形の場合に１．００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【００６１】
本発明において、現像剤の個数基準の粒径頻度分布の平均値を意味する円相当個数平均粒子径Ｄ１と粒径標準偏差ＳＤｄは、粒度分布の分割点ｉでの粒径（中心値）をｄｉ、頻度をｆ_iとすると次式から算出される。
【００６２】
【数２】

【００６３】
また、円形度頻度分布の平均値を意味する平均円形度と円形度標準偏差ＳＤｃは、粒度分布の分訊点ｉでの円形度（中心値）をｃｉ，頻度をｆｃｉとすると、次式から算出される。
【００６４】
【数３】

【００６５】
本発明の現像剤用樹脂に用いられる結着樹脂は、現像剤を製造する際に用いられるものであれば特に限定されるものではない。本発明の現像剤用樹脂に用いられる結着樹脂としては、公知の重合体、又は、共重合体、あるいはこれらの混合物が挙げられる。更に具体的には、スチレン−（メタ）アクリル酸共重合体あるいはポリエステル系樹脂が好ましい。
【００６６】
本発明の現像剤を得るためには、本発明で好ましい範囲の現像剤粒子径や形状を達成可能なものであればその製造方法は特に限定するものではないが、本発明の効果がより顕著に発現するための形状を達成するためには、現像剤の構成成分を溶融混練後に粉砕しさらに球形化処理を施した後に所望の粒子径に分級操作する方法、または、懸濁重合の如き重合方法によって、現像剤を構成する材料を直接モノマー単位から球形化して重合を行い、重合後の粒子を単離する現像剤の製造方法、または、懸濁重合や乳化重合法によってモノマーの重合により現像剤粒子径よりも小さい着色粒子を合成した後にこれらの凝集操作を行って所望の粒度になるように制御する凝集法の如き方法が使用可能である。
【００６７】
現像剤を構成する原材料は、粉砕法であれば上記の如き結着樹脂成分、また、重合法あるいは凝集法であれば結着樹脂を構成するモノマーと、公知の現像剤に使用可能な重合開始剤や架橋剤、分子量調整剤等からなる結着樹脂成分と、公知の着色剤、荷電制御剤、帯電補助剤、離型剤等が使用できる。
【００６８】
一般的に現像剤の機械的ストレスは、構成する原材料の性質と加工後の現像剤中でのこれら構成材料の相互作用状態が影響を与えるものである。従って本発明の如き現像剤においては、これらの機械的ストレスに耐えうる物理的特性、たとえば、粘性力や弾性力特性において強靱なことが現像剤の部材融着を防止し、帯電特性を高める上で好ましく、また、このような粘弾特性を達成するためには、化学的観点から分子量やゲル分、充填剤の分散状態等が適切にコントロールされていることが好ましい。
【００６９】
また、本発明の現像剤及び画像形成方法を用いてモノカラー、あるいはフルカラーの画像形成を行なう場合は、着色剤を変化させることでイエロー、マゼンタ、シアン、ブラックの現像剤を使用することができる。
【００７０】
着色剤として、従来から広く知られている無機、有機の染料、顔料が使用可能である。具体的には次の様なものが挙げられる。
【００７１】
イエロー用着色顔料の具体例としては、縮合アゾ化合物，イソインドリノン化合物，アンスラキノン化合物，アゾ金属錯体，メチン化合物，アリルアミド化合物に代表される化合物が用いられる。さらに具体的には、Ｃ．Ｉ．ピグメントイエロー１，２，３，４，５，６，７，１０，１１，１２，１３，１４，１５，１６，１７，２３，６５，７３，８３、９３、９４、９５、９７、１０９、１１０、１１１、１２０、１２７、１２８、１２９、１４７、１６８、１７４、１７６、１８０、１８１、１９１、Ｃ．Ｉ．バットイエロー１，３，２０等が挙げられる。また、黄鉛、カドミウムイエロー、ミネラルファストイエロー、ネーブルイエロー、ナフトールイエローＳ、ハンザイエローＧ、パーマネントイエローＮＣＧ、タートラジンレーキなども使用することができる。
【００７２】
マゼンタ用着色顔料の具体例としては、Ｃ．Ｉ．ピグメントレッド１，２，３，４，５，６，７，８，９，１０，１１，１２，１３，１４，１５，１６，１７，１８，１９，２１，２２，２３，３０，３１，３２，３７，３８，３９，４０，４１，４８，４９，５０，５１，５２，５３，５４，５５，５７，５８，６０，６３，６４，６８，８１，８３，８７，８８，８９，９０，１１２，１１４，１２２，１２３，１６３，２０２，２０６，２０７，２０９、Ｃ．Ｉ．ピグメントバイオレット１９、Ｃ．Ｉ．バットレッド１，２，１０，１３，１５，２３，２９，３５等が挙げられる。
【００７３】
さらに染料としては、Ｃ．Ｉ．ソルベントレッド１，３，８，２３，２４，２５，２７，３０，４９，８１，８２，８３，８４，１００，１０９，１２１、Ｃ．Ｉ．ディスパースレッド９、Ｃ．Ｉ．ディスパースバイオレット１等の油溶染料、Ｃ．Ｉ．ベーシックレッド１，２，９，１２，１３，１４，１５，１７，１８，２２，２３，２４，２７，２９，３２，３４，３５，３６，３７，３８，３９，４０等の塩基性染料、Ｃ．Ｉ．アシッドレッド１、Ｃ．Ｉ．ダイレクトレッド１，４、Ｃ．Ｉ．モーダントレッド３０等が挙げられる。
【００７４】
シアン用着色顔料の具体例としては、Ｃ．Ｉ．ピグメントブルー２，３，１５，１６，１７、Ｃ．Ｉ．ベーシックブルー３、５、Ｃ．Ｉ．バットブルー６、Ｃ．Ｉ．ダイレクトブルー１，２、Ｃ．Ｉ．アシッドブルー９，１５，４５、Ｃ．Ｉ．モーダントブルー７、又は銅フタロシアニン顔料等がある。
【００７５】
黒用着色顔料の具体例としては、カーボンブラック、アリニンブラック、アセチレンブラック、オイルブラック等がある。また、色用の着色剤を混合し、黒色着色剤として使用することも可能である。
【００７６】
また、上記着色剤の他に、チタンホワイト、Ｃ．Ｉ．ダイレクトグリーン６、Ｃ．Ｉ．ベーシックグリーン４，６、ピグメントグリーンＢ、マラカイトグリーンレーキ、ファイナルイエローグリーンＧ、クロムグリーン、モリブデンオレンジ、パーマネントオレンジＧＴＲ、ピラゾロンオレンジ、ベンジジンオレンジＧ、Ｃ．Ｉ．ベーシックバイオレット１，３，７，１０，１４，１５，２１，２５，２６，２７，２８、Ｃ．Ｉ．ソルベントバイオレット８，１３，１４，２１，２７、マンガン紫、ファストバイオレットＢ、メチルバイオレットレーキ等を使用して、上記色以外の色現像剤用着色剤として使用することも可能である。
【００７７】
これらは、単独、あるいは組合せて使用することができ、通常、結着樹脂１００質量部に対して、０．１〜６０質量部、好ましくは０．５〜２０質量部使用される。
【００７８】
さらに、本発明の現像剤には、定着時の離型性向上のためにワックス成分を含有することが好ましい。
【００７９】
ワックス成分としては、具体的に以下の化合物が挙げられる。
【００８０】
例えばシリコーン樹脂、ポリエステル、ポリウレタン、ポリアミド、エポキシ樹脂、ポリビニルブチラール、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、低分子量ポリエチレン又は低分子量ポリプロピレンの如き脂肪族又は脂環族炭化水素樹脂、芳香族系石油樹脂、塩素化パラフィン、パラフィンワックスなどである。
【００８１】
これらのワックスから、種々の方法によりワックスを分子量により分別したワックスも本発明に好ましく用いられる。また、分別後に酸化やブロック共重合、グラフト変性を行っても良い。
【００８２】
中でも好ましく用いられるワックスは、低分子量ポリプロピレン及びこの副生成物、低分子量ポリエステルおよびエステル系ワックス、脂肪族の誘導体である。
【００８３】
これらのうち、更に好ましいエステルワックスの代表的化合物の例をエステルワックスの一般構造式▲１▼〜▲６▼として以下に示す。
【００８４】
【化１】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基を示し、且つＲ₁とＲ₂との炭素数差が１０以上である基を示し、ｎ及びｍは０〜１５の整数を示し、ｎとｍが同時に０になることはない。）
【００８５】
【化２】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁は炭素数が１〜４０の有機基を示し、ｎ及びｍは０〜１５の整数を示し、ｎとｍが同時に０になることはない。）
【００８６】
【化３】

（式中、ａ及びｂは０〜３の整数を示し、ａ＋ｂは３以下であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基を示し、且つＲ₁とＲ₂との炭素数差が１０以上である基を示し、Ｒ₃は炭素数が１以上の有機基を示し、ｎ及びｍは０〜１５の整数を示し、ｎとｍが同時に０になることはない。）
【００８７】
【化４】

（式中、Ｒ₁及びＲ₂は炭素数が１〜４０の炭化水素基を示し、且つＲ₁及びＲ₂は、お互いに同じでも異なる炭素数でもよい。）
【００８８】
【化５】

（式中、Ｒ₁及びＲ₂は炭素数が１〜４０の炭化水素基を示し、ｎは２〜２０の整数であり、且つＲ₁及びＲ₂は、お互いに同じでも異なる炭素数でもよい。）
【００８９】
【化６】

（式中、Ｒ₁及びＲ₂は炭素数が１〜４０の炭化水素基を示し、ｎは２〜２０の整数であり、且つＲ₁及びＲ₂は、お互いに同じでも異なる炭素数でもよい。）
【００９０】
これらのワックスは定着時の離型性向上を達成するために、現像剤１００質量部中に一般的に２〜３０質量部、より好ましくは５〜２０質量部が使用される。ワックス成分が２質量部未満の場合、ワックスとしての離型効果がほとんど発揮できず、また、ワックス成分が３０質量部を超えると、現像剤の離型性は満足されるものの現像剤の現像性が悪化し、現像スリーブや潜像担持体表面に現像剤が融着するといった弊害を生じやすくなるため好ましくない。
【００９１】
本発明に係るワックス成分は、示差走査熱量計により測定されるＤＳＣ曲線において、昇温時に５０〜１２０℃の領域に最大吸熱ピークを示し、該最大吸熱ピークを含む吸熱ピークの始点のオンセット温度が４０℃以上であることが好ましく、特に該最大吸熱ピークのピーク温度と該オンセット温度の温度差が７〜５０℃の範囲であることが好ましい。
【００９２】
上記温度領域に吸熱ピークおよび最大吸熱ピークを有することにより、低温定着に大きく貢献しつつ、離型性をも効果的に発現し、本発明の定着方法とのマッチングが良好なものとなる。該吸熱ピークが５０℃未満に存在すると現像剤の耐高温オフセット性が著しく損なわれ、１２０℃を超えると現像剤の低温定着性が著しく損なわれる。また、該最大吸熱ピークが昇温測定時に５０℃未満、降温測定時に４０℃未満であると、ワックス成分の自己凝集力が弱くなり、結果として耐高温オフセット性が悪化する。一方、該最大吸熱ピークが１２０℃を超えると、定着温度が高くなり低温オフセットが発生しやすくなり好ましくない。
【００９３】
昇温時のＤＳＣ曲線において、上記温度領域で溶融するワックス成分を用いることにより、他の添加剤の分散性を良好なものとすることができると共に、ワックス成分自身を前述の如き分散状態に容易にコントロールすることができる。
【００９４】
これにより現像剤の良好な定着性はもとより、該ワックス成分による離型効果が効果的に発現され、十分な定着領域が確保されると共に、従来から知られるワックス成分による現像性、耐ブロッキング性や画像形成装置への悪影響が排除されるのでこれらの特性が格段に向上する。特に粒子形状が球形化するに従い、現像剤の比表面積は減少していくので、ワックス成分の分散状態をコントロールすることは、非常に効果的なものとなる。
【００９５】
本発明の現像剤は、該着色粒子表面に、少なくとも金属酸化物微粒子を有し、該現像剤中の金属酸化物微粒子の遊離率が０．０１〜１０％であることが必要である。
【００９６】
金属酸化物微粒子としてはマグネシウム、亜鉛、アルミニウム、チタン、コバルト、ジルコニウム、マンガン、セリウム、ストロンチウム等の酸化物粉体及びチタン酸カルシウム、チタン酸マグネシウム、チタン酸ストロンチウム、チタン酸バリウム等の複合金属酸化物粉体等を挙げることが出来る。さらに好ましくは酸化チタン、チタン酸ストロンチウム、シリカ微粒子、マグネシウム複合金属酸化物粉体である。
【００９７】
尚、本発明に用いられるシリカ微粒子のうち特に好ましいものは、ケイ素ハロゲン化合物の蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ、及び水ガラス等から製造されるいわゆる湿式シリカの両方が使用可能であるが表面及びシリカ微粒子の内部にあるシラノール基が少なく、またＮａ₂Ｏ，ＳＯ₃ ^2-等の製造残査のない乾式シリカの方が好ましい。
【００９８】
また、乾式シリカにおいては製造工程において例えば、塩化アルミニウム、又は塩化チタンなど他の金属ハロゲン化合物をケイ素ハロゲン化合物と共に用いることによってシリカと他の金属酸化物の複合微粒子を得ることも可能であり、それらも包含する。
【００９９】
本発明に用いられるシリカ微粒子は、必要に応じて、疎水化、摩擦帯電性の制御などの目的のために、シランカップリング剤、有機ケイ素化合物等の処理剤で表面処理されていても良く、その方法も公知の方法が用いられ、シリカ粒子と反応あるいは物理吸着する処理剤で表面処理される。
【０１００】
そのような処理剤としては、例えば、ヘキサメチルジシラザン、卜リメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシリルメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサン、及び１分子当り２から１２個のシロキサン単位を有し末端に位置する単位にそれぞれ１個宛のＳｉに結合した水酸基を含有するジメチルポリシロキサン等がある。これらは１種あるいは２種以上の混合物で用いられる。
【０１０１】
また、酸化チタンとしては、公知のアナターゼ型の酸化チタンやルチル型の酸化チタンが使用できる。マグネシウム複合金属酸化物粉体としては、公知のハイドロタルサイト類化合物が好適に使用できる。
【０１０２】
該現像剤中の金属酸化物微粒子の遊離物とは、現像剤中の着色粒子から外れた金属酸化物微粒子のことを指すものである。従って、外添等の公知の表面処理条件によってコントロールできたり、また、金属酸化物微粒子の使用量によってもコントロールすることが可能である。
【０１０３】
現像剤母粒子の炭素原子に対する外添剤微粒子の存在は、元素内に含まれる原子の比率を利用する方法が使用できる。母粒子（炭素を主体とする）に対して、遊離した外添剤由来のたとえばＳｉ原子は、プラズマ中に導入するとそれぞれの元素の励起に伴う発光スペクトルが得られる。このスペクトルをリアルタイムでモニターすることで、この励起に伴う発光スペクトルを検出することにより分析を行なうものである。
【０１０４】
本測定方法は、現像剤の分析方法として、電子写真学会年次大会（通算９５回）、“ Ｊａｐａｎ Ｈａｒｄｃｏｐｙ’９７ ”論文集、「新しい外添評価方法−パーティクルアナライザによる現像剤分析−」、鈴木俊之、高原寿雄、電子写真学会主催、１９９７年７月９〜１１日、に開示されている現像剤分析方法を使用して行なうことができる。
【０１０５】
この分析方法によれば、複数元素の励起に伴う発光スペクトルを同時検出することが可能であり、さらに発光スペクトルの周期性についても測定することができる。
【０１０６】
外添剤の遊離率を求める方法としては、同期性を利用した。
【０１０７】
同一粒子中に含まれる元素は、同一周期で励起発光スペクトル（同期スペクトル）を生じるが、一方、外添剤遊離物のように単体で存在する元素は、現像剤母体とは同期せずに単独で励起発光スペクトル（非同期スペクトル）を生じる。これらの各元素に由来する励起発光スペクトルの非同期／同期を定量的に求めることによって、現像剤母体に対する特定元素の遊離率を求めた。
【０１０８】
具体的測定方法としては、横河電機（株）製ＰＴ１０００を用い以下の条件にて測定した後、Ｃ原子を基準とした外添剤原子の発光の同期性を以下の式に当てはめて遊離率を求めた。外添剤として、ハイドロタルサイトの場合は例えばＭｇ原子が、酸化チタンの場合はＴｉ原子の同期性を測定することで外添剤の遊離率を求めた。
【０１０９】
一例として、マグネシウム元素を有する複合金属酸化物粉体を含有する現像剤の測定方法について述べる。
【０１１０】
＜＜横河電機（株）製ＰＴ１０００の測定条件＞＞
・一回の測定におけるＣ原子検出数：５００〜２５００
・ノイズカットレベル：１．５以下
・ソート時間：２０ｄｉｇｉｔｓ
・ガス：Ｏ₂ ０．１％、Ｈｅガス
・分析波長：
Ｃ原子 ：２４７．８６０ｎｍ
Ｍｇ原子：２８５．２１０ｎｍ
・使用チャンネル：
Ｃ原子 ：１又は２
Ｍｇ原子 ：１又は２
・Ｍｇ原子の遊離率
（Ｃ原子と同時に発光しなかったＭｇ原子のカウント数）／（Ｃ原子と同時に発光したＭｇ原子のカウント数＋Ｃ原子と同時に発光しなかったＭｇ原子のカウント数）×１００
【０１１１】
本発明は、現像部分での帯電付与性が特徴であるが、このような特徴を発現するためには、公知の荷電制御剤を適宜使用することが好ましい。現像剤を負荷電性に制御するものの例として下記物質がある。例えば、有機金属化合物、キレート化合物が有効であり、具体的には、モノアゾ金属化合物、アセチルアセトン金属化合物、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属化合物がある。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類などがある。また、尿素誘導体、含金属サリチル酸系化合物、含金属ナフトエ酸系化合物、ホウ素化合物、４級アンモニウム塩、カリックスアレーン、ケイ素化合物、スチレン−アクリル酸共重合体、スチレン−メタクリル酸共重合体、スチレン−アクリル−スルホン酸共重合体、ノンメタルカルボン酸系化合物等が挙げられる。
【０１１２】
また、現像剤を正荷電性に制御するものの具体例として下記物質がある。例えば、ニグロシン及び脂肪酸金属塩等による変性物、グアニジン化合物、イミダゾール化合物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルホン酸塩、テトラブチルアンモニウムテトラフルオロボレートなどの４級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドなどのジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートなどのジオルガノスズボレート類；これらを単独で或は２種類以上組合せて用いることができる。これらの中でも、ニグロシン系、４級アンモニウム塩の如き荷電制御剤が特に好ましく用いられる。
【０１１３】
本発明の現像剤中の金属酸化物微粒子は、帯電安定性、現像性、流動性、耐久性向上の目的で、疎水化シリカ微粉末が好ましく使用できる。
【０１１４】
疎水化処理を行なうシリカ微粉末母体としては、特に限定するものではなく公知のシリカが使用できるが、疎水化処理後のシリカ微粉末の特性として、ＢＥＴ法で測定した窒素吸着による比表面積が２０ｍ²／ｇ以上（特に３０〜４００ｍ²／ｇの範囲内）のものが現像性、流動性の点で好ましい。
【０１１５】
また、疎水化剤の具体例としては、シリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他の有機ケイ素化合物が挙げられる。これらの処理剤は単独でもあるいは混合して使用しても良い。
【０１１６】
これらのシリカ微粉末を疎水化する方法は、公知の製造方法により行なうことが可能である。なお、疎水化シリカ微粉末の疎水化の程度（疎水化度）としては、メタノール／水混合溶媒系で濡れ性が９０％以上であることが本願の目的から好ましい。
【０１１７】
また、疎水化シリカ微粉末の使用量としては、現像剤粒子１００質量部に対してシリカ微粉体０．０１〜８質量部、好ましくは０．１〜５質量部使用するのが良い。
【０１１８】
シリコーンオイル処理された無機微粉体があり、具体的な例としては、シリコーンオイル処理により疎水化したシリカ微粉末、シリコーンオイル処理により疎水化した酸化チタン、シリコーンオイル処理により疎水化したアルミナなどが挙げられる。
【０１１９】
本発明で好適に使用できるその他の外添剤としては以下のような公知の無機粉体中で本願の範囲を満たすものであれば特に限定するものではない。第２の外添剤として具体的には、マグネシウム、亜鉛、アルミニウム、セリウム、コバルト、鉄、ジルコニウム、クロム、マンガン、ストロンチウム、錫、アンチモンの如き金属の酸化物；チタン酸カルシウム、チタン酸マグネシウム、チタン酸ストロンチウムの如き複合金属酸化物；炭酸カルシウム、炭酸マグネシウム、炭酸アルミニウムの如き金属塩；カオリンの如き粘土鉱物；アパタイトの如きリン酸化合物；炭化ケイ素、窒化ケイ素の如きケイ素化合物；カーボンブラックやグラファイトの如き炭素粉末などのものが使用できる。
【０１２０】
【実施例】
現像剤供剥離部材の製造例（１）
本例ではワンショット方式で現像剤供給剥離部材の成型を行った。即ち、現像剤供給剥離部材の芯金として、Φ５ｍｍの芯金を用意し、その外周面に接着剤を塗布して、円筒形金型の成型キャビティ内にセットした。次いで、液状としたイソシアネートと、成形後に発泡状態が連続気泡になるような量を調整したエチレンオキサイドを予め混入したポリオールとをキャビティ内に流し込み、６０℃程度に温調した。この雰囲気中で約３０分保持し反応を完了させる。これにより発泡性ウレタンスポンジが成型され、反応終了後、これを金型から取り出した後、成形金型との界面で生じた平滑面を研磨し、その表面が発泡層で、その径がΦ１６ｍｍになるように調整した。このようにして得られた発泡弾性体の任意断面の連泡セル数を測定したところ１００個／２５ｍｍであった。この現像剤供給剥離部材を、現像剤供給剥離部材（１）とする。
【０１２１】
現像剤供給剥離部材の製造例（２）
現像剤供給剥離部材の製造例（１）でエチレンオキサイド量を調整した他は現像剤供給剥離部材の製造例（１）と同様の方法で、１４０個／２５ｍｍの連泡セル数を有する現像剤供給剥離部材（２）を得た。
【０１２２】
現像剤供給剥離部材の製造例（３）
現像剤供給剥離部材の製造例（１）でイソシアネートとエチレンオキサイドを使用する代わりに、アクリルゴムと発泡剤としてのスルフォニルヒドラジド化合物を適量使用し、成形温度を１００℃とする他は現像剤供給剥離部材の製造例（１）と同様の方法で、５５個／２５ｍｍの連泡セル数を有する現像剤供給剥離部材（３）を得た。
【０１２３】
現像剤供給剥離部材の比較製造例（１）
現像剤供給剥離部材の製造例（１）で液状のワンショット成型方法を用いる代わりに、ミラブルタイプで発泡性のないウレタンゴム成形を行なうことで、発泡を持たない弾性体の現像剤供給剥離部材（４）を得た。
【０１２４】
現像剤供給剥離部材の比較製造例（２）
現像剤供給剥離部材の製造例（３）で発泡剤としてのスルフォニルヒドラジド化合物量を減量した他は現像剤供給剥離部材の製造例（１）と同様の方法で、４０個／２５ｍｍの単泡セル数を有する現像剤供給剥離部材（５）を得た。
【０１２５】
現像剤供給剥離部材の比較製造例（３）
現像剤供給剥離部材の製造例（１）でエチレンオキサイド量を調整した他は現像剤供給剥離部材の製造例（１）と同様の方法で、１７０個／２５ｍｍの発泡セル数を有する現像剤供給剥離部材（６）を得た。
【０１２６】
現像剤供給剥離部材の比較製造例（４）
現像剤供給剥離部材として、Φ１６ｍｍのポリエステル性ファーブラシを用意し、これを現像剤供給剥離部材（７）とした。
【０１２７】
現像剤供給剥離部材の製造例で製造した現像剤供給剥離部材の内容と表面特性を表１にまとめる。
【０１２８】
【表１】

【０１２９】
現像剤の製造例（１）
高速撹拌装置ＴＫ−ホモミキサーを具備した２リットル用四つ口フラスコ中に、イオン交換水７１０質量部と０．１ｍｏｌ／Ｌ−Ｎａ₃ＰＯ₄水溶液４５０質量部を添加し、回転数を７０００ｒｐｍに調整し、６０℃に加温せしめた。ここに１．０ｍｏｌ／Ｌ−ＣａＣｌ₂水溶液６８質量部を徐々に添加し、微小な難水溶性分散剤Ｃａ₃（ＰＯ₄）₂を含む水系分散媒体を調製した。
【０１３０】
一方、
・スチレン単量体 ８０質量部
・２−エチルヘキシルアクリレート単量体 ２０質量部
・ポリエステル １０質量部
（酸価２０ｍｇＫＯＨ／ｇ、ピーク分子量７５００）
・カーボンブラック （一次粒子径４４ｎｍ） １０質量部
・エステルワックスＮｏ．４
（Ｒ₁、Ｒ₂：Ｃ₁₈Ｈ₃₇） １０質量部
・モノアゾクロム錯体 １質量部
上記材料をボールミルを用い充分に分散させた後、ボールミルより内容物を単離した。この内容物に対して、重合開始剤である２，２’−アゾビス（２，４−ジメチルブチロニトリル）３質量部を添加した重合性単量体組成物を、前記水系分散媒体中に投入し回転数７０００ｒｐｍを維持しつつ造粒した。その後、パドル撹拌翼で撹拌しつつ６０℃で４時間反応させた後、８０℃で５時間重合させ、更に８５℃で減圧し蒸留し、反応を終了させた。
【０１３１】
反応終了後、懸濁液を冷却し、塩酸を加えて難水溶性分散剤Ｃａ₃（ＰＯ₄）₂を溶解し、濾過、水洗、乾燥した後に風力分級によって所望の粒度に分級し、着色粒子（１）を得た。
【０１３２】
続いて、該着色粒子１００質量部に対して、ＢＥＴ比表面積が１３０ｍｍ²／ｇの疎水性シリカを１．３質量部をヘンシェルミキサー内に投入し、通常の処理条件の１．５倍に相当する強度で高速撹拌処理することで本発明の現像剤（１）を調製した。
【０１３３】
本現像剤中の表面金属酸化物の遊離率をＣ−Ｓｉ原子の非同期成分で測定したところ０．９％であった。また、現像剤（１）の形状を測定したところ、円相当径は６．６μｍ、平均円形度は０．９８０、円形度標準偏差は０．０２９、さらに、コールターマルチサイザーでの粗粒量は０．３体積％であった。
【０１３４】
現像剤の製造例（２）
表２に示す着色剤を使用するよう変更する他は現像剤の製造例（１）同様の方法で、着色粒子（２）を得た。
【０１３５】
続いて、該着色粒子１００質量部に対して、ＢＥＴ比表面積が１３０ｍｍ²／ｇの疎水性シリカを１．３質量部とアナターゼ型の酸化チタン０．５質量部をヘンシェルミキサー内に投入し、通常の処理条件の１．５倍に相当する強度で高速撹拌処理することで本発明の現像剤（２）を調製した。本現像剤中の疎水性シリカの遊離率は０．７％、酸化チタンの遊離率はＣ−Ｔｉ原子の非同期成分で測定したところ０．５％であった。また、現像剤（２）の形状を測定したところ、平均円形度は０．９８０、円形度標準偏差は０．０３０、さらに、コールターマルチサイザーでの粗粒量は０．４体積％であった。
【０１３６】
現像剤の製造例（３）、（４）
表２に示す着色剤を使用するよう変更する他は現像剤の製造例（１）同様の方法で現像剤（３）、（４）を得た。
【０１３７】
なお、ハイドロタルサイトの遊離率はＣ−Ｍｇ原子の非同期成分で測定した。
【０１３８】
現像剤の製造例（５）
着色粒子の製造方法を以下に示す溶融粉砕法により行った。具体的な製造方法としては、まず下記材料をヘンシェルミキサー（ＦＭ−７５型、三井三池化工機（株）製）で混合した。
・スチレン−アクリル酸ブチル−マレイン酸ブチルハーフエステル共重合体
（ピーク分子量：約４００００、ガラス転移点Ｔｇ：６３℃） １００質量部
・カーボンブラック（一次粒子径４０ｎｍ） １０質量部
・ジカルボン酸アルミ錯体 ２質量部
・ポリエチレン
（分子量分布＝１．０８、ＤＳＣ吸熱ピーク：１０７℃） ５質量部
【０１３９】
続いて、スクリュー押し出し混練機のスクリュー最後尾側のニーディング部におけるバレル部設定温度をＴ０（℃）＝１１０℃、溶融混練機排出口温度Ｔ１＝１５０℃になるように二軸混練機（ＰＣＭ−３０型、池貝鉄工（株）製）で混練した。得られた混練物を冷却し、ハンマーミルにて１ｍｍ以下に粗粉砕し、現像剤粗砕物を得た。次に、該粗砕物を衝突式気流粉砕機で微粉砕した後、機械的衝撃力を利用する表面改質装置を用いて球形化処理を行い、球形の粉砕原料を得た。次に、得られた粉砕原料を、多分割分級装置エルボジェット分級装置（日鉄鉱業製）に導入し、所望の粒度分布になるよう分級操作して着色粒子（５）を得た。
【０１４０】
続いて、該着色粒子（５）１００質量部対して、疎水性シリカを１．８質量部とハイドロタルサイトを０．３質量部を、製造例（１）同様の方法で表面処理することで本発明の現像剤（５）を調製した。本現像剤中の疎水性シリカの遊離率は６．５％、ハイドロタルサイトの遊離率はＣ−Ｍｇ原子の非同期成分で測定したところ０．３％であった。
【０１４１】
また、現像剤（２）の形状を測定したところ、平均円形度は０．９７６、円形度標準偏差は０．０３６、さらに、コールターマルチサイザーでの粗粒量は０．４体積％であった。
【０１４２】
現像剤の製造例（６）
表２に示す処方のみ変更する他は現像剤の製造例（５）同様の方法で、現像剤（６）を製造した。
【０１４３】
本現像剤中の疎水性シリカの遊離率は８．１％、ポリメタクリル酸メチルの遊離率は測定不能であった。
【０１４４】
現像剤の製造例（７）
現像剤の製造例（５）において、機械的衝撃力を利用する表面改質装置を用いて球形化処理を行なう工程を省き、且つ、分級条件を操作した他は現像剤の製造例（５）と同様の方法で、現像剤（７）を製造した。
【０１４５】
また、現像剤（７）の形状を測定したところ、平均円形度は０．９５２、円形度標準偏差は０．０４２、さらに、コールターマルチサイザーでの粗粒量は１．４体積％であった。
【０１４６】
現像剤の比較製造例（１）
現像剤の製造例（１）で得られた着色粒子（１）を用い、表面微粒子としてポジ性に帯電する平均粒子径が０．３μｍのポリスチレン粒子を外添し、比較現像剤（１）を製造した。得られた比較現像剤（１）の形状を測定したところ、平均円形度は０．９８０、円形度標準偏差は０．０２９、さらに、コールターマルチサイザーでの粗粒量は０．５体積％であった。
【０１４７】
現像剤の比較製造例（２）
現像剤の製造例（７）における現像剤の分級条件を操作し粗粒量が１．６体積％になるよう調整したものについて、疎水性シリカを１．５質量部用いて表面処理する他は現像剤の製造例（７）と同様にして、比較現像剤（２）を調製した。
【０１４８】
現像剤の比較製造例（３）
現像剤の製造例（７）における現像剤の分級条件を操作し粗粒量が１．６体積％になるよう調整したものについて、疎水性シリカ２．５質量部とポリメタクリル酸メチル０．２質量部を添加し、ヘンシェルミキサーにて通常の処理条件で高速撹拌処理することで本発明の比較現像剤（３）を調製した。
【０１４９】
以上合成した現像剤を表２にまとめる。
【０１５０】
【表２】

【０１５１】
実施例（１）
次に、本実施例で使用する現像装置について、具体的に説明する。
【０１５２】
図１は、本実施例で使用した一成分接触現像方式の電子写真プロセスを利用した６００ｄｐｉレーザービームプリンタ（キヤノン製：ＬＢＰ−８６０）改造機の概略図である。本実施例では以下の（ａ）〜（ｈ）の部分を改造した装置を使用した。
（ａ）プロセススピードを９４ｍｍ／ｓに変更した。
（ｂ）装置の帯電方式をゴムローラ当接による直接帯電とし、印加電圧を直流成分とした。
（ｃ）現像剤担持体をカーボンブラックを分散したシリコーンゴムからなる中抵抗ゴムローラ（１６φ、硬度ＡＳＫＥＲ Ｃ４５度、抵抗１０⁵Ω・ｃｍ、Ｒａ＝２．１μｍ、Ｒｚ＝３．５μｍ）に変更し、静電潜像担持体にニップ幅３．０ｍｍで圧接するよう配置した。
（ｄ）該現像剤担持体の回転周速は、静電潜像担持体との接触部分において順方向であり、該現像剤担持体に対する該静電潜像担持体の相対速度が１５５％の速度になるよう調整した。
（ｅ）静電潜像担持体を有機系の静電潜像担持体とし、ローラ式接触帯電部材で交流と直流の混合した電圧を印加して静電潜像担持体表面の電位を均一に帯電するものとした。
（ｆ）現像剤供給剥離部材として現像剤供給剥離部材（１）を使用した。また、現像剤供給剥離部材と現像剤担持体とが、侵入量２ｍｍになるよう相互の軸間を調整した。さらにこれらの相対速度が対向で９０％になるよう回転方向及び回転速度を設定した。
（ｇ）厚さ０．５ｍｍのリン青銅表面に、溶剤希釈したウレタンをディッピング加工したブレードを、現像剤担持体との接触圧が線圧約２９．６Ｎ／ｍ（約３０ｇ／ｃｍ）となるように取付けた。
（ｈ）現像時の印加電圧をＤＣ成分のみとした。
（ｊ）静電潜像担持体上のクリーニングブレードの当接圧が線圧約３９．２Ｎ／ｍ（約４０ｇ／ｃｍ）となるように取付けた。
【０１５３】
これらのプロセスカートリッジの改造に適合するよう電子写真装置に以下のように改造及びプロセス条件設定を行った。
【０１５４】
改造された装置はローラ帯電器を用い像担持体を一様に帯電する。帯電に次いで、レーザ光で画像部分を露光することにより静電潜像を形成し、現像剤により可視画像とした後に、電圧を＋７００Ｖ印加したローラにより現像剤像を転写材に転写するプロセスを持つ。概略を図１に示した。
【０１５５】
以上の画像形成方法を用いて、現像剤として現像剤（１）を用いて、温度・湿度が、２５℃・１０％、及び、３０℃・５０％の環境下で３％印字率のＡ４画像を連続５０００枚出力した。その後、評価画像として、後述の画像をサンプリングし、得られた画像を評価した。この評価結果を表３にまとめる。
【０１５６】
実施例（２）〜（６）、参考例（１）、及び、比較実施例（１）〜（３）
実施例（１）で使用した画像形成装置を用い、現像剤として現像剤（２）〜（７）、及び、比較実施例（１）〜（３）を用いて、実施例（１）同様に画像を出力し、得られた画像を評価した。
【０１５７】
ここで、実施例（１）〜（６）、参考例（１）が良好な性能を発揮したが、これは、該現像剤中の金属酸化物微粒子の遊離率が適当な範囲にあり、且つ、該現像剤中の粗粒量が良好な範囲にあるため、本発明の効果であるところの現像剤の十分な供給と、十分な剥ぎ取り性能を維持できたこと、および、粗粒及び遊離外添剤に起因する現像弊害の影響を極力抑え留ことで、耐久性に優れた安定した画像形成が可能になったものである。
【０１５８】
また、実施例（１）〜（５）では、現像剤の粒子形状が適切であることで、さらに本発明の効果が顕著に現れることが明らかになった。これは、現像剤の粒子形状が本発明の如き範囲にあるとき、連泡性の現像剤供給剥離部材のセル内部への現像剤の進入する量が適当であり、また、その形状分布が球形に近いことで現像剤の吐出性も良好であるため、所望する量の現像剤供給が問題なく行われたことによるものである。さらに、このように現像剤の吐出性が優れていることによって、常に現像剤供給剥離部材表面のセルが露出されており、その結果、現像剤担持体上の現像後の残留現像剤を剥離する能力を常に維持することができる。従って、このような現像剤形状と現像剤供給剥離部材との組合せによって、耐久中の現像剤供給、及び現像剤剥離が良好に行われていることを意味している。
【０１５９】
また、かかる現像剤は、低湿及び高温といった過酷な環境下の耐久試験にもかかわらず、耐久中に規制部材表面や静電潜像担持体表面に現像剤が融着せず、耐久中の濃度変化が少なく、また、耐久後半でも、初期と変わらない安定した性能が発揮できている。このような効果が発現する機構については明らかではないが、現像を繰り返し行っていく上で、現像剤中の金属酸化物微粒子の遊離率が０．０１〜１０％である現像剤は、現像剤供給剥離部材のセル中の遊離金属酸化物微粒子の蓄積物を生じさせにくくするため、現像剤の帯電均一性を向上させることができるためであると考えられる。
【０１６０】
実施例（８）、（９）、及び比較実施例（４）〜（７）
現像剤として、現像剤（１）を使用し、画像形成装置として実施例（１）で使用した現像装置の現像剤供給剥離部材を、現像剤供給剥離部材の製造例（２）〜（３）、及び、現像剤供給剥離部材の比較製造例（１）〜（４）に替えた他は実施例（１）と同様に画像を出力し、得られた画像を評価した。
【０１６１】
また、図４には、比較製造例（４）で使用したファーブラシ型の画像形成方法について例示した。
【０１６２】
実施例（８）、（９）、及び比較実施例（４）〜（７）の結果において、現像剤剥離供給部材の製造例（２）、（３）の系が安定した現像性能を示し、中でも、現像剤剥離供給部材の製造例（２）、（３）が良好な性能を示したが、これは、現像剤剥離供給部材のセル数が適当な範囲にあるため、現像剤中の巨大粒子や外添剤中の遊離物が、かかる連泡セル中に捕捉され、現像に関与しなくなったことによるものと考えられる。
【０１６３】
実施例（１）〜（９）、及び比較実施例（１）〜（７）のプリントアウト評価結果を表３にまとめる。（評価の詳細は後述）
【０１６４】
【表３】

【０１６５】
実施例（１０）
図２に示すフルカラー画像形成装置を用い、フルカラーの画像形成を試みた。まず、現像器４−１、４−２、４−３、４−４に現像剤（１）、現像剤（２）、現像剤（３）、現像剤（４）を導入した。次いで、現像器４−１によって静電潜像担持体１上の静電潜像を現像する。
【０１６６】
顕像化された該静電潜像担持体上のトナー像は、静電潜像担持体１の下面部に接触させて配設されている中間転写体５に、一次転写電圧（例えば、±０．１〜±５ｋＶ）によって一次転写される。このとき、着脱自在なクリーニング手段１０は、中間転写体５から脱離されることによって、中間転写体５上に現像器４−１により顕像化されたトナー像が保持される。
【０１６７】
続いて同様の方法で現像器４−２、４−３、４−４を順次現像して中間転写体５上に第１色、第２色、第３色、第４色のトナー像を重ね合わせ、これらのトナー像を中間転写体５の外面に配置された転写材６を介して転写ローラ７との間の転写電圧（例えば、±０．５〜±１０ｋＶ）により転写材６上に一括転写される。転写材６へのトナー像の転写後に、着脱自在なクリーニング手段１０により、中間転写体５の表面がクリーニングされる。
【０１６８】
続いて、転写材６上のトナー像は加熱加圧定着手段Ｈによって定着され永久画像を得る。
【０１６９】
この画像形成装置を用いて、２３℃、４０％５０％環境下で印字率３％のフルカラー画像を連続で４０００枚の耐久試験を実施した。その結果、現像スジ、現像ムラ、画像濃度の追従性に優れ、現像スジの発生がない安定したカラー画像が得られた。
【０１７０】
実施例１〜９、並びに、比較例１〜７中に記載の評価項目の説明とその評価基準について述べる。
【０１７１】
本実施例で使用した評価項目について説明する。
【０１７２】
［プリントアウト画像評価］
＜１＞現像スジ
低湿度環境（２５℃・１０％）、及び、及び高温度環境（３０℃・５０％）にて、画像印字率が３％になるような画像濃度で耐久を行った後、６００ｄｐｉの３０％印字率のハーフトーン画像を出力し得た画像について現像スジを目視で評価した。
Ａ：非常に良好（良好）
Ｂ：良好 （ほぼ気にならないレベル）
Ｃ：実用可 （若干あるが実用上問題にならないレベル）
Ｄ：実用難あり（スジが確認でき、場合によっては問題になるレベル）
Ｅ：実用不可 （スジが非常に目立ち、実用上問題になるレベル）
【０１７３】
＜２＞現像ムラ
低湿度環境（２５℃・１０％）、及び、及び高温度環境（３０℃・５０％）にて、画像印字率が３％になるような画像濃度で耐久を行った後、６００ｄｐｉの３０％印字率のハーフトーン画像を出力し得た画像について現像ムラを目視で評価した。
Ａ：非常に良好（良好）
Ｂ：良好 （ほぼ気にならないレベル）
Ｃ：実用可 （若干あるが実用上問題にならないレベル）
Ｄ：実用難あり（モヤが確認でき、場合によっては問題になるレベル）
Ｅ：実用不可 （モヤが非常に目立ち、実用上問題になるレベル）
【０１７４】
＜３＞画像濃度
通常の複写機用普通紙（７５ｇ／ｍ²）に所定の枚数のプリントアウトを終了した時の画像濃度について、先端近傍の画像濃度と、先端近傍と中段以降の画像濃度の差を求め、この２点について、下記基準で評価した。なお、画像濃度と濃度差の２点でいずれも満たすものからＡ−Ｅランクで評価した。
【０１７５】
尚、画像濃度は「マクベス反射濃度計」（マクベス社製）を用いて、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
Ａ：先端濃度が１．４０以上、且つ、濃度差が０．１未満
Ｂ：先端濃度が１．３５以上、１．４０未満、且つ、濃度差が０．１以上、０．２未満
Ｃ：先端濃度が１．２５以上、１．３５未満、且つ、濃度差が０．２以上、０．４未満
Ｄ：先端濃度が１．００以上、１．２５未満、且つ、濃度差が０．４以上、０．６未満
Ｅ：先端濃度が１．００未満、且つ、濃度差が０．６以上
【０１７６】
【発明の効果】
以上説明したように、本発明によれば、一成分接触現像方式において、現像剤供給剥離部材と現像剤のマッチングにおいて、現像剤の十分な供給力と、十分な剥ぎ取り性能を維持し、画像濃度の安定した現像剤、及び画像形成方法が得られる。また、現像剤中の粗粒及び遊離外添剤に起因する現像弊害の影響を極力抑えた画像形成方法を提供することが可能である。
【図面の簡単な説明】
【図１】本発明に好適に用いられる画像形成方法の概略構成図である。
【図２】本発明に好適に用いられる中間転写体を有するフルカラー画像形成方法の例である。
【図３】現像剤供給剥離部材の連泡、単泡のイメージ図である。
【図４】比較実施例（７）で使用したファーブラシ型の画像形成方法である。
【符号の説明】
１ 感光体
２ 帯電ローラ
３ レーザー光
４−１ イエロー現像器
４−２ マゼンタ現像器
４−３ シアン現像器
４−４ 黒現像器
５ 中間転写体ドラム
６ 転写材
７ 転写ローラ
８ クリーナ（感光体ドラム用クリーナ）
１０ クリーナ（中間転写体ドラム用クリーナ）
１００ 現像剤担持体
１１１ ファーブラシ型現像剤供給剥離手段
１２７ 転写材（記録材）
１００ 静電潜像担持体（感光体ドラム）
１１７ 帯電装置（帯電ローラ）
１４０ 現像器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet recording method, or the like, or a developer used in a full-color image forming method, and an image forming method. It is. More specifically, the present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a fax machine, which forms a developer image on a latent electrostatic image bearing member in advance and then transfers the image onto a transfer material to form an image. The present invention relates to a developer used for electrostatic printing and an image forming method.
[0002]
[Prior art]
Conventionally, electrophotography generally utilizes a photoconductive material, forms an electrostatic latent image on a latent image carrier (photoconductor) by various means, and then develops the latent image using a developer, If necessary, an image is transferred to a recording material using direct or indirect means, and then fixed by heating, pressure, etc. to obtain a copy.
[0003]
Conventionally, the two-component development method and the one-component development method are widely used as the development method. However, as a printer for business or personal use by electrophotography, in recent years, due to the demand for miniaturization and high performance, Component development methods are increasing. Among them, the non-magnetic one-component contact method has been used from the viewpoint of low developer consumption and high image quality.
[0004]
A general one-component contact development method is to visualize an electrostatic latent image by bringing a developer carrier coated with a developer on the surface of the developer carrier into a thin layer and an electrostatic latent image carrier. Further, a recorded image is obtained by sequentially transferring and fixing the visible image on a recording material. Here, the developer takes an arbitrary charged state. However, the charging to the developer is performed by forming a thin layer of the developer on the surface of the developer carrying member by the regulating member and developing the surface of the regulating member at the same time. This is done by rubbing the agent. Further, the electrostatic latent image is visualized in terms of potential by using an electric field in the developing portion by utilizing the charging polarity of the developer. Therefore, by applying appropriate electrification to the developer, it is possible to prevent image defects such as image fogging on the white background portion, insufficient development density, and lack of lines, and achieve high-quality image formation.
[0005]
Therefore, it is necessary to coat the developer on the developer carrying member. As the developer used in the non-magnetic one-component contact image forming method, for example, in JP-A-63-276064, the number average particle size and the volume average particle size are related to the particle size of the developer supplied from a sponge roller. An invention that defines the relationship is disclosed. A developer having such a particle size has the effect that there is little change in the particle size of the developer due to continuous copying and an image equivalent to the initial image can be obtained even after continuous copying, but the amount of coarse particles (coarse particles) in the developer There is no description about image streaks, which is a problem in the non-magnetic one-component contact image forming method.
[0006]
In the non-magnetic one-component contact image forming method, the developer supplying / separating member serves as a developer supplying unit, and also serves as a unit for removing an undeveloped developer remaining after development. Is preferable for printing with the same quality.
[0007]
Japanese Patent Application Laid-Open No. 5-181352 proposes an image forming apparatus using a foamed elastic body having a different compressive elastic modulus in the radial direction as a developer supply / peeling member. In such an image forming method, it is possible to prevent uneven coating on the developer carrier and increase in driving torque due to clogging of the developer. Japanese Patent Application Laid-Open No. 2001-066896 discloses an invention relating to a peeling member having a different layer structure and having an intrusion prevention layer between these layers. Such a stripping member is effective in preventing uneven coating on the developer carrying member due to clogging of the developer. However, in these publications, there is no detailed description about the developer, and there is a high possibility that it will occur with respect to development streaks that may occur with respect to development problems due to the coarse particle amount of the developer.
[0008]
Further, in Japanese Patent Application Laid-Open No. 10-239882, an elastic developer supply / peeling member is a foam having a continuous bubble ratio of 30% or more, and the biting depth of the supply roller with respect to the development roller is 0.4 mm or less. In addition, a developing device is disclosed, wherein the developer has a shape factor SF-1 of 150 or less and SF-2 of 140 or less. According to the developing device of the present invention, by controlling the shape of the developer, the developer that has entered the cell can be easily discharged from the cell, and an increase in the driving torque of the supply roller can be suppressed. is there. However, there is no description regarding the external additive liberation rate of the developer used in such a developing device. As a result of examining such an example, a large amount of free additives of the external additive in the developer accumulates on the surface and inside of the foamed elastic body, particularly in a low humidity environment, and uneven consumption of the developer occurs before and after durability. In particular, when much of the developer has been consumed in the second half of the endurance, the free external additive concentrated and accumulated during the endurance is released into the developer at a high concentration. In general, the external additive has a particle size smaller than that of the developer, and a charged substance having such a particle size tends to have a high charge amount. In particular, in a low humidity environment, the charge amount tends to increase due to the influence of humidity. Therefore, when such a system is used in a developing system such as a combination of an elastic developer carrier and an elastic blade, the non-uniformity of the image due to these external additives being discharged together in the latter half of the endurance under low humidity. (Image unevenness) and image streaks occur, which is problematic in practice.
[0009]
Further, from the viewpoint of print quality, proposals have been made that define the amount of free matter (free amount) not attached to the developer among the surface treatment agents of the developer. For example, JP-A-4-145448, JP-A-6-258863, and JP-A-7-043931 have proposed a toner in which hydrophobic silica is partially fixed and partially released on the toner surface. .
[0010]
JP-A-6-342224 discloses a toner having a Si atom liberation rate of 0.5 to 20% with respect to the base toner. Furthermore, Japanese Patent Laid-Open No. 2000-047425 discloses a toner in which the external additive released from the mother particles is 5% or less with respect to the total toner. In these gazettes, a toner that uses a particle analyzer to limit the liberation rate of the external additive has been proposed, but there is no description of the relationship with the developer supply peeling member, and the effects of these combinations are mentioned. It has not been.
[0011]
Further, the amount of coarse particles in the developer tends to hardly come out after being taken into the foamed elastic body because of its size. In particular, such a tendency is conspicuous in the open-cell-type supply / peeling member. In such a system, when the developer in the latter half of the endurance decreases, these coarse-grained developers are released onto the developer carrier together. Since the coarse particles are clogged between the developer regulating member and the developer carrying member, the developer coat layer on the developer carrying member is disturbed, causing image streaks.
[0012]
[Problems to be solved by the invention]
Therefore, the above prior art cannot be an effective means for image stability in a low-humidity environment when using an open-cell developer supply / peeling member in the non-magnetic one-component contact image forming method.
[0013]
Accordingly, an object of the present invention is to provide a developer and an image forming method that do not cause the above problems.
[0014]
That is, the first object of the present invention is to maintain a sufficient supply power of the developer and a sufficient stripping performance in matching of the developer supply peeling member and the developer, and a developer having a stable image density, and An object is to provide an image forming method.
[0015]
Furthermore, a second object of the present invention is to provide a developer that suppresses the effects of development problems caused by coarse particles and free external additives as much as possible, and an image forming method having a configuration in which these effects are unlikely to occur. It is in.
[0016]
[Means and Actions for Solving the Problems]
The present inventor has conducted intensive studies, and in a one-component contact contact development system, is a system using a developer supply peeling member made of open-cell foamed elastic material having 50 to 150 cells per 25 mm. By using a developer having a liberation rate of metal oxide fine particles in the developer of 0.01 to 10%, the free external additive in a low humidity environment is abnormally accumulated in the foam cell. It was possible to prevent the developer on the developing roller from being peeled off and insufficient supply of the developer, and as a result, it was found that the above problems could be solved and the present invention was achieved.
[0017]
Further, in the one-component contact contact development method, a system using a developer supplying / peeling member made of a foamed elastic body, and using a developer having a coarse particle amount of 1.5% by volume or less by using a developer, Concentration of the coarse portion of the developer in the foamed elastic body can be prevented, and as a result, the developer supplied to the developing roller can be obtained in an initial state even in the second half of the endurance. It has been found that the clogging of the developer between the regulating member and the developer carrying member can be prevented, and the occurrence of development streaks in the output image can be suppressed.
[0018]
As a result of further investigation, the inventors have found that the effect of the present application is more remarkable and the durability is improved when the particle shape of the developer is more spherical.
[0019]
  That is, the present invention relates to a non-magnetic one-component contact image forming method having a developer supply peeling member arranged so as to be pressed against a developer carrier.To the lawLeave
  The developer supply release member is an open-cell foamed elastic body having 50 to 150 cells per 25 mm,
  The developer is a non-magnetic one-component developer having at least a binder resin, colored particles composed of a colorant and a release agent, and at least metal oxide fine particles on the surface of the colored particles. The liberation rate of the metal oxide fine particles is 0.01 to 10%, and the coarse particles in the developer(12.7μm or more)The amount is 1.5% by volume or lessThe
  In the developer-based circle equivalent diameter-circularity scattergram measured by the flow type particle image measuring apparatus, the average circularity of the developer is 0.950 to 0.990, and the circularity standard deviation is 0. Less than 040It is characterized byPaintingThe present invention relates to an image forming method.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically.
[0021]
An image forming apparatus that is one of the features of the present invention will be described in detail below with reference to the accompanying drawings.
[0022]
FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to the present application.
[0023]
The electrophotographic image forming apparatus of this example is a non-magnetic one-component contact developing type laser beam printer having a contact charging method and a cleaning mechanism.
[0024]
In FIG. 1, the developing device 140 is located in a developing container 140 containing a non-magnetic one-component developer 142 as a developer, and an opening extending in the longitudinal direction in the developing container 140, and faces the latent image carrier 100. The developer carrying member 104 is provided, and the electrostatic latent image on the latent image carrying member 100 is developed and visualized.
[0025]
The developer carrying member 104 is horizontally provided with the substantially right half-peripheral surface shown in the drawing entering the developer container 140 through the opening and the left substantially half-peripheral surface exposed to the outside of the developer container 140. The surface exposed to the outside of the developing container 140 is in contact with the latent image carrier 100 located on the left side of the developing device 104 in the drawing.
[0026]
The developer carrying member 104 is rotationally driven in the direction of the arrow, and the surface thereof has appropriate irregularities for increasing the probability of rubbing with the developer 142 and for carrying the developer well. .
[0027]
The surface roughness Ra as defined in “JIS B 0601” is 0.2 to 5 as appropriate irregularities for increasing the probability of rubbing with the developer 142 and transporting the developer satisfactorily. 0.0 μm and Rz must be in the range of 8.0 μm or less. If Ra is set to 0.2 to 5.0 as the surface roughness of the developer carrying member, both high image quality and high durability can be achieved. If the surface roughness Ra of the developer carrier exceeds 5.0, it is difficult to make the developer layer on the developer carrier thin, and the chargeability of the developer is not improved. I cannot expect improvement. The developer carrying capacity on the surface of the developer carrier is suppressed by setting it to 5.0 or less, the developer layer on the developer carrier is thinned, and the developer carrier and the developer are in contact with each other. Since the number of times increases, the chargeability of the developer is also improved, so that the image quality is synergistically improved. On the other hand, when the surface roughness Ra is less than 0.2, it becomes difficult to control the developer coating amount. Further, in order to more efficiently perform the rubbing at the developing portion, it is preferable that the surface roughness Ra of the developer carrier is in the above range.
[0028]
As the developer carrying member 104, an elastic roller member having an elastic layer with respect to the core member, or a metal cylindrical tube surface coated with elastic conductive rubber is used. As the conductive rubber, known rubbers such as silicone rubber, urethane rubber, NBR rubber, and those coated with a conductive layer on the surface thereof are used.
[0029]
As an example, NBR base layer is surface-coated with ether urethane, diameter 16 mm, resistance 10^Four-10⁸An Ω elastic roller can be used. The peripheral speed of the latent image carrier 100 is 50 to 170 mm / s, and the peripheral speed of the developer carrier 104 is rotated at a peripheral speed that is 1 to 2 times the peripheral speed of the latent image carrier.
[0030]
The elastic layer hardness of the elastic roller surface is preferably about 20 to 65 degrees (ASKER C), more preferably 30 to 60 degrees, from the viewpoint of both developability and durability. Known materials and structures can be used for the elastic roller. In particular, solid rubber elastic bodies such as silicone rubber, urethane rubber and NBR, or foamed elastic bodies thereof are preferably used. Moreover, a well-known multilayer structure roller having a coating layer different from the central part on the surface can also be used. In addition, a known surface treatment may be performed for the purpose of imparting chargeability or imparting transportability. At this time, it is preferable to take a series in which the charging series on the surface of the elastic layer is positioned at a counter electrode for applying a charge to the developer from the viewpoints of tribocharging and replacement of the developer on the developing roller.
[0031]
Above the developer carrier 104, a metal plate such as SUS, a rubber material such as urethane or silicone, or a metal thin plate of SUS or phosphor bronze having spring elasticity is used as a base, and the developer carrier 104 is contacted. A regulating member 143 made of a rubber material bonded to the contact surface side is supported by the blade support metal plate, and is provided so that the vicinity of the free end side is in contact with the outer peripheral surface of the developer carrier 104 by surface contact. The contact direction is a so-called counter direction in which the front end side is located upstream of the rotation direction of the developer carrier 104 with respect to the contact portion.
[0032]
As an example of the developer regulating member, a plate-like urethane rubber having a thickness of 1.0 mm is bonded to a blade support metal plate, and the contact pressure with respect to the developer carrier 5 is 22.5 to 34.3 N / m. (23 to 35 g / cm). The linear pressure was measured based on a value obtained by inserting three metal thin plates having a known friction coefficient into the abutting portion and pulling out the central one with only a spring.
[0033]
The developer supplying / peeling member according to the present invention is characterized in that it is an open-cell foamed elastic body having 50 to 150 cells per 25 mm.
[0034]
The developer supply peeling member 141 is in contact with the contact portion of the developer regulating member 143 with the surface of the developer carrier 104 on the upstream side in the rotation direction of the developer carrier 104 and is rotatably supported. . As this structure, a foamed skeleton-like sponge structure is preferable from the viewpoint of supplying the developer 142 to the developer carrying member 104 and stripping off the undeveloped developer, and the material is silicone rubber, urethane rubber, SBR rubber. For example, a developer supplying / peeling member made of a foamed elastic material obtained by foaming a base material made of a plastic material such as a rubber member such as polypropylene or polyvinyl chloride is used.
[0035]
The contact width of the developer supply peeling member 141 with respect to the developer carrier 104 is preferably 1 to 8 mm, and more preferably 2 to 7 mm. Further, it is preferable that the developer supplying / separating member 141 has a relative speed with respect to the developer carrying member 104 at the contact portion.
[0036]
The outermost layer of the developer supply / separating means has two functions of supplying the developer to the developer carrying member 104 and peeling off the undeveloped developer that did not contribute to the development. The developer on the developer carrying member is mechanically peeled off by rubbing the edge portion of the foam cell.
[0037]
FIG. 3 shows a schematic diagram of the elastic body of the developer supply and peeling means. In the case where the surface layer of the developer supplying / separating means is solid rubber or the single-bubble elastic body shown in FIG. 3a, the amount of the developer is apt to be reduced, and the amount of developer necessary for the development is reduced. 3b, the developer supply and release means of the open-cell elastic body shown in FIG. 3b can include a developer in the open-cell, so that the developer-supporting body has a necessary amount of developer. Can be supported.
[0038]
As a result, a desired developer amount can be conveyed to the developer carrier 104.
[0039]
Further, from the viewpoint of the developer transportability, the open-cell ratio of the developer supply / peeling member was investigated, and the number of cells per 25 mm was preferably 10 or more, more preferably the number of cells per 25 mm. It turned out that the effect of this invention is acquired when it is 50-150 pieces.
[0040]
Further, when the open cell ratio of the developer supply / peeling member is in this range of cells, it is possible to suppress development problems such as development streaks due to coarse particles in the developer. The reason for this is that when the number of cells is 50 to 150 per 25 mm, coarse particles that are coarse particles in the developer are easily trapped in the open cell, and the developer is consumed due to durability and the durability ends. This is considered to be due to staying in the foamed cell until it does, and not participating in the development.
[0041]
Here, the “number of cells” refers to the average number of foam cells having an arbitrary cross section, and the number of cells is obtained by measuring the number of cells per unit area of the foam cell from an enlarged image of the arbitrary cross section. Therefore, “the number of cells is 50 to 150 per 25 mm” indicates that the average value of the number of foamed cells is 50 to 150 per 25 mm.
[0042]
The thickness of the foamed layer that can be used in the developer supply / peeling member in the present invention can be 2 to 15 mm, and more preferably 5 to 10 mm. When the thickness of the foamed layer is less than 2 mm, the transport amount of the developer is reduced, so that it is difficult to transport a desired amount of the developer. On the other hand, if it exceeds 15 mm, the axial torque of the developer supply / peeling member itself increases, and in some cases, there is a high possibility that the component will be damaged due to the torque increase.
[0043]
In addition to the urethane rubber described above, NBR rubber (nitrile rubber), silicone rubber, acrylic rubber, hydrin rubber, ethylene propylene rubber (EPDM rubber) can be used as the material for the foam layer that can be used in the developer supply release member of the present invention. ), Generally used rubbers such as chloroprene rubber, styrene butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, and composite mixtures thereof can be used. By using a common foaming agent in these rubber materials, a foamed elastic body can be obtained.
[0044]
A method for producing a foamed layer that can be used in the developer supply release member of the present invention will be described. Prepare a metal core for the developer supply release member, apply adhesive to the outer peripheral surface, set it in the molding cavity of the cylindrical mold, and simultaneously mix the liquid isocyanate and the polyol already mixed with ethylene oxide. The reaction is completed by pouring into the cavity and holding in an atmosphere preliminarily adjusted to about 60 ° C. for about 30 minutes. This is a so-called one-shot method, whereby a foamable urethane sponge is molded, and after completion of the reaction, it is removed from the mold. The gas generated by foaming when the sponge is formed is vented from the upper part of the mold. Since the surface of the foamed elastic body thus obtained has a smooth surface formed at the interface with the mold at the time of molding, it is adjusted so that the surface becomes a foamed layer by polishing. .
[0045]
When a developer having a liberation ratio of metal oxide fine particles in the developer of 0.01 to 10% is used in a developer supply peeling member having this number of cells, reproduction of a halftone image by charge-up is achieved. Improves. Such charge-up is particularly noticeable in a low-humidity environment. For example, in a system in which the liberation rate of metal oxide fine particles in the developer exceeds 10%, halftone image unevenness is likely to occur. In a scene where a fine gradation such as a human image is required for an image or the like, image detriment due to developer charge-up becomes conspicuous. There are various reasons for this charge-up, and one of the reasons is that the released metal oxide particles in the developer enter the cell of the developer supply peeling member, and are firmly inside the cell. After the formation of the free metal oxide layer, when the adhesion amount reaches a saturation amount, the external additive accumulation is released into the developer all at once. Such external additive accumulation is fused to the surface of the developer regulating member and the surface of the developer carrying member, or by itself polishing the surface of these members, the surface of the developer regulating member and the development are developed. The surface property of the surface of the agent carrier is changed, and the charge amount of the developer is partially disturbed. Such disturbance of the charge amount is manifested as uneven development especially in a delicate electrostatic latent image state in which a halftone image is output. Therefore, it is considered that the unevenness of the halftone image is caused as described above. .
[0046]
In addition, regarding the developer particle shape to be described later, when considering matching with the foamable developer supply peeling member, the number of developer-based circle equivalent diameter-circularity scattergram measured by the flow type particle image measuring device The developer developer may have a shape distribution such that the average circularity of the developer is 0.950 to 0.990 and the circularity standard deviation is less than 0.040 in matching with the continuous foaming supply member. . Such matching is particularly effective in the case of printing a high printing rate image that requires continuous developer supply, and the one having such a developer shape distribution is a continuous output of a high print image and the latter half of the image. It was possible to prevent a decrease in concentration. The reason for this is that the amount of the developer entering the cell inside the open-cell developer supply / peeling member is appropriate, and the shape distribution is close to a sphere, so that the developer discharge is good. This is because the desired amount of developer was supplied without any problem. Further, the developer discharge performance is excellent in this manner, so that the cells on the surface of the developer supply / peel member are always exposed, and as a result, the residual developer after development on the developer carrier is peeled off. Ability can be maintained at all times. Therefore, the combination of the developer shape and the developer supply / peeling member makes it possible to satisfactorily supply the developer and remove the developer during durability.
[0047]
In the above, the development method and the case where the present invention is applied to a process cartridge comprising a developing device detachable from the image forming apparatus main body have been described. However, the developing is configured to be fixed in the image forming apparatus main body and replenish only the developer. You may apply to an apparatus. In addition, at least the above-described developing device is provided, and if necessary, the photosensitive drum, the cleaning blade, the waste developer container, and the charging device may be formed as a process cartridge that can be detachably attached to the image forming apparatus main body. You may apply.
[0048]
In the case of using a combination of a conductive regulating member and a developer carrier, it is also preferable to apply a DC electric field and / or an AC electric field between the regulating member and the developer carrier. By applying such an electric field, uniform thin layer coating and uniform chargeability are improved, and sufficient image density can be achieved and a good quality image can be obtained.
[0049]
Furthermore, the present invention has a mechanism for blade cleaning the surface of the electrostatic latent image carrier after transfer, but a known blade can be used as a cleaning member for blade cleaning.
[0050]
As a charging method after blade cleaning, a known contact or non-contact charging method can be used, but a contact charging method that has an effect of suppressing the generation of ozone during charging is more preferable. In the combination of the image forming method of the present invention and the developer, most of the transfer residue remaining on the surface of the latent electrostatic image bearing member after transfer is composed of hydrophobic silica fine particles and a second outer layer having a polarity opposite to that of the hydrophobic silica particles. Since it is an additive, it is necessary to select a material that is compatible with the combination of the above-described blade cleaning member and contact charging. When these combinations do not function properly, particles mainly composed of external additives adhere to the charging member, and the resistance value of the surface of the charging roller is locally increased, so that the surface of the electrostatic latent image carrier surface is increased. This is not preferable because charging is hindered and as a result, image defects due to poor charging occur.
[0051]
Next, the developer which is the second aspect of the present invention will be described.
[0052]
The developer is a non-magnetic one-component developer having at least a binder resin, colored particles composed of a colorant and a release agent, and at least metal oxide fine particles on the surface of the colored particles, and the metal oxidation in the developer The release rate of the fine particles is 0.01 to 10%, and the amount of coarse particles in the developer is 1.5% by volume or less.
[0053]
The amount of coarse particles in the developer in the present invention is preferably 1.5% by volume or less. The amount of coarse particles in the developer tends to be difficult to come out after being taken into the foamed elastic body due to its size. In particular, such a tendency is conspicuous in the open-cell supply / peeling member, and when the developer in the latter half of the endurance is low, these coarse-grained developers are released onto the developer carrier together, and the developer regulation Since the coarse particles are clogged between the member and the developer carrying member, the developer coating layer on the developer carrying member is disturbed and causes image streaks. Such accumulation of coarse-grained components tends to become significant when the amount of coarse particles in the developer exceeds 1.5% by volume, and when developing stability is required, the amount of coarse particles in the developer is 1. It is necessary to be 5% by volume or less.
[0054]
The amount of coarse particles can be measured by various methods such as Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter). In the present invention, the number distribution is obtained using Coulter Multisizer (manufactured by Coulter). An interface (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) were connected and output as data obtained by dividing the particle size range into 16 parts.
[0055]
As a specific measuring method, 1% NaCl aqueous solution is prepared using 1st grade sodium chloride as the electrolytic solution. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. Next, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes using an ultrasonic disperser, and the volume distribution is measured by measuring the volume and number of the developer of 2 μm or more using the 100 μm aperture as the aperture by the Coulter Multisizer. And the number distribution were calculated.
[0056]
Then, the volume-based volume average particle diameter obtained from the volume distribution according to the present invention (Dv: the median value of each channel is the representative value of the channel), the volume variation coefficient (Sv), and the number-based number obtained from the number distribution. The weight-based coarse powder amount (12.7 μm or more) obtained from the length average particle size (D1), the length variation coefficient (S1), and the volume distribution was obtained.
[0057]
The equivalent-circle diameter, circularity, and frequency distribution of the developer in the present invention are used as a simple method for quantitatively expressing the shape of the developer particles. In the present invention, the flow-type particle image measuring device is used. Measurement was performed using an FPIA-1000 type (manufactured by Toa Medical Electronics Co., Ltd.), and the calculation was performed using the following equation.
[0058]
[Expression 1]

[0059]
Here, the “particle projected area” is the area of the binarized developer particle image, and the “peripheral length of the particle projected image” is the contour line obtained by connecting the edge points of the developer particle image. Define length.
[0060]
The circularity in the present invention is an index indicating the degree of unevenness of the developer particles, and indicates 1.00 when the developer particles are perfectly spherical. The more complicated the surface shape, the smaller the circularity. .
[0061]
In the present invention, the circle-equivalent number average particle diameter D1 and the particle diameter standard deviation SDd, which mean the average value of the particle number frequency distribution based on the number of developers, are the particle diameter (center value) at the dividing point i of the particle size distribution. di, frequency f_iThen, it is calculated from the following formula.
[0062]
[Expression 2]

[0063]
In addition, the average circularity and the circularity standard deviation SDc, which mean the average value of the circularity frequency distribution, can be expressed by the following equation, where the circularity (center value) at the distribution point i of the particle size distribution is ci and the frequency is fci. Calculated.
[0064]
[Equation 3]

[0065]
The binder resin used for the developer resin of the present invention is not particularly limited as long as it is used when the developer is produced. Examples of the binder resin used in the developer resin of the present invention include known polymers, copolymers, and mixtures thereof. More specifically, a styrene- (meth) acrylic acid copolymer or a polyester resin is preferable.
[0066]
In order to obtain the developer of the present invention, the production method is not particularly limited as long as the developer particle diameter and shape within the preferable range of the present invention can be achieved, but the effect of the present invention is more remarkable. In order to achieve a shape that can be expressed in the above, a constituent component of the developer is pulverized after melt-kneading and further spheronized, and then classified to a desired particle size, or polymerization such as suspension polymerization Depending on the method, the material constituting the developer is directly spheronized from the monomer unit and polymerized, and then the developer is produced by polymerizing the developer by suspension polymerization or emulsion polymerization. It is possible to use a method such as an agglomeration method in which colored particles smaller than the particle size of the agent are synthesized and then these agglomeration operations are performed to control the particles to have a desired particle size.
[0067]
The raw materials constituting the developer are the binder resin components as described above in the case of the pulverization method, the monomers constituting the binder resin in the case of the polymerization method or the aggregation method, and the polymerization initiation that can be used for known developers. A binder resin component composed of an agent, a crosslinking agent, a molecular weight adjusting agent, and the like, a known colorant, a charge control agent, a charge auxiliary agent, a release agent, and the like can be used.
[0068]
In general, the mechanical stress of the developer is influenced by the properties of the constituent raw materials and the interaction state of these constituent materials in the developer after processing. Therefore, in a developer such as the present invention, the physical characteristics that can withstand these mechanical stresses, for example, the toughness in the viscous force and elastic force characteristics prevent the developer from fusing members and improve the charging characteristics. In order to achieve such viscoelastic properties, it is preferable that the molecular weight, gel content, dispersed state of the filler, and the like are appropriately controlled from a chemical viewpoint.
[0069]
In addition, when mono-color or full-color image formation is performed using the developer and image forming method of the present invention, yellow, magenta, cyan, and black developers can be used by changing the colorant. .
[0070]
As the colorant, conventionally known inorganic and organic dyes and pigments can be used. Specific examples include the following.
[0071]
Specific examples of the color pigment for yellow include compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. More specifically, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 168, 174, 176, 180, 181, 191, C.I. I. Vat yellow 1, 3, 20 etc. are mentioned. Further, yellow lead, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartrazine lake and the like can also be used.
[0072]
Specific examples of the color pigment for magenta include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned.
[0073]
Further, as the dye, C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper thread 9, C.I. I. Oil-soluble dyes such as disperse violet 1, C.I. I. Basic dyes such as Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40 , C.I. I. Acid Red 1, C.I. I. Direct Red 1, 4, C.I. I. Modern tread 30 etc. are mentioned.
[0074]
Specific examples of the color pigment for cyan include C.I. I. Pigment blue 2, 3, 15, 16, 17, C.I. I. Basic Blue 3, 5, C.I. I. Bat Blue 6, C.I. I. Direct Blue 1, 2, C.I. I. Acid Blue 9, 15, 45, C.I. I. For example, Modern Blue 7 or copper phthalocyanine pigment.
[0075]
Specific examples of black coloring pigments include carbon black, arinin black, acetylene black, and oil black. Moreover, it is also possible to mix a colorant for color and use it as a black colorant.
[0076]
In addition to the colorant, titanium white, C.I. I. Direct Green 6, C.I. I. Basic Green 4,6, Pigment Green B, Malachite Green Lake, Final Yellow Green G, Chrome Green, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, C.I. I. Basic violet 1,3,7,10,14,15,21,25,26,27,28, C.I. I. Solvent violet 8, 13, 14, 21, 27, manganese purple, fast violet B, methyl violet lake, etc. can also be used as a color developer for a color developer other than the above colors.
[0077]
These can be used singly or in combination. Usually, 0.1 to 60 parts by mass, preferably 0.5 to 20 parts by mass are used with respect to 100 parts by mass of the binder resin.
[0078]
Further, the developer of the present invention preferably contains a wax component in order to improve releasability at the time of fixing.
[0079]
Specific examples of the wax component include the following compounds.
[0080]
For example, silicone resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin such as low molecular weight polyethylene or low molecular weight polypropylene, aromatic petroleum Resins, chlorinated paraffin, paraffin wax and the like.
[0081]
Of these waxes, waxes obtained by fractionating waxes by molecular weight by various methods are also preferably used in the present invention. In addition, oxidation, block copolymerization, and graft modification may be performed after fractionation.
[0082]
Among these, low molecular weight polypropylene and its by-products, low molecular weight polyesters and ester waxes, and aliphatic derivatives are preferably used.
[0083]
Among these, examples of more preferable representative compounds of ester wax are shown below as general structural formulas (1) to (6) of the ester wax.
[0084]
[Chemical 1]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R₁And R₂Represents an organic group having 1 to 40 carbon atoms, and R₁And R₂And n and m are integers of 0 to 15, and n and m are not 0 at the same time. )
[0085]
[Chemical 2]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R₁Represents an organic group having 1 to 40 carbon atoms, n and m represent integers of 0 to 15, and n and m are not 0 at the same time. )
[0086]
[Chemical Formula 3]

(Wherein, a and b represent an integer of 0 to 3, a + b is 3 or less, R₁And R₂Represents an organic group having 1 to 40 carbon atoms, and R₁And R₂And a group having a carbon number difference of 10 or more, and R_ThreeRepresents an organic group having 1 or more carbon atoms, n and m represent an integer of 0 to 15, and n and m are not 0 at the same time. )
[0087]
[Formula 4]

(Wherein R₁And R₂Represents a hydrocarbon group having 1 to 40 carbon atoms, and R₁And R₂May be the same or different carbon numbers. )
[0088]
[Chemical formula 5]

(Wherein R₁And R₂Represents a hydrocarbon group having 1 to 40 carbon atoms, n is an integer of 2 to 20 and R₁And R₂May be the same or different carbon numbers. )
[0089]
[Chemical 6]

(Wherein R₁And R₂Represents a hydrocarbon group having 1 to 40 carbon atoms, n is an integer of 2 to 20 and R₁And R₂May be the same or different carbon numbers. )
[0090]
These waxes are generally used in an amount of 2 to 30 parts by mass, more preferably 5 to 20 parts by mass in 100 parts by mass of the developer in order to achieve improvement in releasability at the time of fixing. When the wax component is less than 2 parts by mass, the release effect as a wax can hardly be exhibited. When the wax component exceeds 30 parts by mass, the developer releasability is satisfied, but the developer developability. This is not preferable because it is liable to cause a problem that the developer is fused to the surface of the developing sleeve or the latent image carrier.
[0091]
The wax component according to the present invention has a maximum endothermic peak in the region of 50 to 120 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter, and the onset temperature of the start point of the endothermic peak including the maximum endothermic peak Is preferably 40 ° C. or higher, and in particular, the temperature difference between the peak temperature of the maximum endothermic peak and the onset temperature is preferably in the range of 7 to 50 ° C.
[0092]
By having an endothermic peak and a maximum endothermic peak in the above temperature range, the mold release property is also effectively exhibited while greatly contributing to low-temperature fixing, and matching with the fixing method of the present invention becomes favorable. When the endothermic peak is present below 50 ° C., the high temperature offset resistance of the developer is remarkably impaired, and when it exceeds 120 ° C., the low temperature fixability of the developer is remarkably impaired. Further, when the maximum endothermic peak is less than 50 ° C. at the time of temperature rise measurement and less than 40 ° C. at the time of temperature fall measurement, the self-cohesion force of the wax component becomes weak, and as a result, the high temperature offset resistance deteriorates. On the other hand, if the maximum endothermic peak exceeds 120 ° C., the fixing temperature becomes high and low temperature offset tends to occur, which is not preferable.
[0093]
By using a wax component that melts in the above temperature range in the DSC curve at the time of temperature rise, the dispersibility of other additives can be improved, and the wax component itself can be easily dispersed as described above. Can be controlled.
[0094]
As a result, not only good fixability of the developer but also a release effect by the wax component is effectively expressed, a sufficient fixing area is secured, and developability and blocking resistance by a conventionally known wax component Since the adverse effect on the image forming apparatus is eliminated, these characteristics are remarkably improved. In particular, as the particle shape becomes spherical, the specific surface area of the developer decreases, so it becomes very effective to control the dispersion state of the wax component.
[0095]
The developer of the present invention needs to have at least metal oxide fine particles on the surface of the colored particles, and the liberation rate of the metal oxide fine particles in the developer needs to be 0.01 to 10%.
[0096]
Metal oxide fine particles include oxide powders such as magnesium, zinc, aluminum, titanium, cobalt, zirconium, manganese, cerium, and strontium, and composite metal oxides such as calcium titanate, magnesium titanate, strontium titanate, and barium titanate. Examples include powdered materials. More preferred are titanium oxide, strontium titanate, silica fine particles, and magnesium composite metal oxide powder.
[0097]
Particularly preferred among the silica fine particles used in the present invention are so-called dry methods produced by vapor phase oxidation of silicon halogen compounds or so-called dry silica called fumed silica, and so-called water glass. Both wet silica can be used, but there are few silanol groups on the surface and inside the silica particles, and Na₂O, SO_Three ^2-Dry silica having no production residue such as is preferred.
[0098]
In dry silica, composite fine particles of silica and other metal oxides can be obtained by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0099]
The silica fine particles used in the present invention may be surface-treated with a treatment agent such as a silane coupling agent or an organosilicon compound for the purpose of hydrophobization and triboelectric charge control, if necessary. As the method, a known method is used, and the surface is treated with a treating agent that reacts or physically adsorbs with silica particles.
[0100]
Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane. , Bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyl Dimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane 1,3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and containing hydroxyl groups bonded to one Si at each terminal unit . These are used alone or in a mixture of two or more.
[0101]
As titanium oxide, known anatase type titanium oxide or rutile type titanium oxide can be used. As the magnesium composite metal oxide powder, known hydrotalcite compounds can be preferably used.
[0102]
The free metal oxide fine particles in the developer refer to metal oxide fine particles that are separated from the colored particles in the developer. Therefore, it can be controlled by known surface treatment conditions such as external addition, and can also be controlled by the amount of metal oxide fine particles used.
[0103]
The presence of the external additive fine particles with respect to the carbon atoms of the developer mother particles can be performed by a method utilizing the ratio of atoms contained in the element. When, for example, Si atoms derived from the liberated external additive are introduced into the plasma with respect to the base particles (mainly carbon), emission spectra associated with the excitation of the respective elements are obtained. By analyzing this spectrum in real time, analysis is performed by detecting the emission spectrum accompanying this excitation.
[0104]
In this measurement method, as an analysis method of developer, Electrophotographic Society Annual Meeting (95 times in total), “Japan Hardcopy '97” paper collection, “New External Evaluation Method-Developer Analysis with Particle Analyzer”, Suzuki The developer analysis method disclosed in Toshiyuki, Toshio Takahara, sponsored by the Electrophotographic Society, July 9-11, 1997 can be used.
[0105]
According to this analysis method, it is possible to simultaneously detect an emission spectrum accompanying excitation of a plurality of elements, and it is also possible to measure the periodicity of the emission spectrum.
[0106]
Synchronicity was used as a method for determining the liberation rate of the external additive.
[0107]
Elements contained in the same particle generate an excitation emission spectrum (synchronous spectrum) in the same period, while elements existing alone such as external additive free substances are not synchronized with the developer matrix alone. Produces an excitation emission spectrum (asynchronous spectrum). By quantitatively determining the asynchronous / synchronous of the excitation emission spectrum derived from each of these elements, the liberation rate of the specific element with respect to the developer matrix was determined.
[0108]
As a specific measurement method, after measuring under the following conditions using PT1000 manufactured by Yokogawa Electric Corporation, the release rate is obtained by applying the synchronization of emission of external additive atoms based on C atoms to the following formula. Asked. As the external additive, for example, Mg atom in the case of hydrotalcite, and Ti atom in the case of titanium oxide were measured to determine the liberation rate of the external additive.
[0109]
As an example, a method for measuring a developer containing a composite metal oxide powder containing magnesium element will be described.
[0110]
<< Measurement conditions for PT1000 manufactured by Yokogawa Electric Corporation >>
-Number of detected C atoms in one measurement: 500-2500
・ Noise cut level: 1.5 or less
・ Sort time: 20 digits
・ Gas: O₂  0.1% He gas
・ Analysis wavelength:
C atom: 247.860 nm
Mg atom: 285.210 nm
・ Channels used:
C atom: 1 or 2
Mg atom: 1 or 2
-Mg atom liberation rate
(Count number of Mg atoms not emitting simultaneously with C atoms) / (Count number of Mg atoms emitting simultaneously with C atoms + Count number of Mg atoms not emitting simultaneously with C atoms) × 100
[0111]
The present invention is characterized by charge imparting properties in the development portion. In order to exhibit such characteristics, it is preferable to use a known charge control agent as appropriate. Examples of those that control the developer to be negatively charged include the following substances. For example, an organic metal compound and a chelate compound are effective, and specifically, there are a monoazo metal compound, an acetylacetone metal compound, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid metal compound. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol. Also, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene- An acrylic-sulfonic acid copolymer, a nonmetal carboxylic acid compound, etc. are mentioned.
[0112]
Moreover, the following substances are given as specific examples of controlling the developer to be positively charged. For example, modified products with nigrosine and fatty acid metal salts, quaternary ammonium salts such as guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and the like Onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and their lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, Gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; DOO, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination of these alone, or two or more kinds. Among these, a charge control agent such as a nigrosine-type quaternary ammonium salt is particularly preferably used.
[0113]
As the metal oxide fine particles in the developer of the present invention, hydrophobized silica fine powder can be preferably used for the purpose of improving charging stability, developability, fluidity and durability.
[0114]
The silica fine powder matrix to be hydrophobized is not particularly limited and known silica can be used. However, as a characteristic of the silica fine powder after the hydrophobizing treatment, the specific surface area by nitrogen adsorption measured by the BET method is 20 m.²/ G or more (especially 30 to 400 m²/ G) is preferable in terms of developability and fluidity.
[0115]
Specific examples of the hydrophobizing agent include silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having a functional group, and other organosilicon compounds. These treatment agents may be used alone or in combination.
[0116]
The method for hydrophobizing these silica fine powders can be performed by a known production method. The degree of hydrophobicity (hydrophobization degree) of the hydrophobized silica fine powder is preferably 90% or more in a methanol / water mixed solvent system for the purpose of the present application.
[0117]
The amount of the hydrophobized silica fine powder used is 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the developer particles.
[0118]
There are inorganic fine powders treated with silicone oil. Specific examples include silica fine powder hydrophobized by silicone oil treatment, titanium oxide hydrophobized by silicone oil treatment, and alumina hydrophobized by silicone oil treatment. It is done.
[0119]
Other external additives that can be suitably used in the present invention are not particularly limited as long as they satisfy the scope of the present application in the following known inorganic powders. Specific examples of the second external additive include magnesium, zinc, aluminum, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, and oxides of metals such as antimony; calcium titanate, magnesium titanate, Complex metal oxides such as strontium titanate; metal salts such as calcium carbonate, magnesium carbonate and aluminum carbonate; clay minerals such as kaolin; phosphate compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; carbon black and graphite Such as carbon powder can be used.
[0120]
【Example】
Production Example of Developer Delivering Member (1)
In this example, the developer supplying / separating member was molded by a one-shot method. That is, a core metal having a diameter of 5 mm was prepared as a core metal for the developer supply / peeling member, and an adhesive was applied to the outer peripheral surface thereof and set in a molding cavity of a cylindrical mold. Next, the liquefied isocyanate and the polyol preliminarily mixed with ethylene oxide whose amount was adjusted so that the foamed state became continuous after molding were poured into the cavity, and the temperature was adjusted to about 60 ° C. Hold in this atmosphere for about 30 minutes to complete the reaction. As a result, a foamable urethane sponge is molded. After the reaction is completed, the foamed urethane sponge is taken out of the mold, and then the smooth surface generated at the interface with the molding mold is polished. The surface is a foamed layer and the diameter thereof is 16 mm. It adjusted so that it might become. The number of open cells in an arbitrary cross section of the foamed elastic body thus obtained was 100/25 mm. This developer supply / peeling member is referred to as a developer supply / peeling member (1).
[0121]
Production Example of Developer Supply Peeling Member (2)
Developer having the number of open cells of 140 cells / 25 mm in the same manner as in Production Example (1) of Developer Supply Peeling Member except that the amount of ethylene oxide was adjusted in Production Example (1) of Developer Supply Peeling Member A supply peeling member (2) was obtained.
[0122]
Production Example of Developer Supply Peeling Member (3)
Instead of using isocyanate and ethylene oxide in Production Example (1) for Developer Supply Peeling Member, use an appropriate amount of acrylic rubber and sulfonyl hydrazide compound as a foaming agent, and set the molding temperature to 100 ° C. In the same manner as in the member production example (1), a developer supply / peeling member (3) having a number of open cells of 55 cells / 25 mm was obtained.
[0123]
Comparative production example (1) of developer supply release member
Instead of using the liquid one-shot molding method in production example (1) of the developer supply / peeling member, the developer supply / peeling member is an elastic body that does not have foaming, by forming a urethane rubber that is not foamable and is a millable type (4) was obtained.
[0124]
Comparative production example (2) of developer supply release member
40/25 mm single-bubble cells in the same manner as in the developer supply release member production example (1) except that the amount of the sulfonyl hydrazide compound as the foaming agent was reduced in the production example (3) of the developer supply release member. A developer supply release member (5) having a number was obtained.
[0125]
Comparative production example of developer supply release member (3)
Developer supply having the number of foamed cells of 170 cells / 25 mm in the same manner as in the developer supply / peel member production example (1) except that the amount of ethylene oxide was adjusted in the developer supply / peel member production example (1). A release member (6) was obtained.
[0126]
Comparative production example (4) of developer supply / peeling member
A polyester fur brush having a diameter of 16 mm was prepared as a developer supply / peeling member, which was designated as a developer supply / peeling member (7).
[0127]
Table 1 summarizes the contents and surface characteristics of the developer supply release member manufactured in the manufacture example of the developer supply release member.
[0128]
[Table 1]

[0129]
Developer production example (1)
In a 4-liter flask for 2 liters equipped with a high-speed stirring device TK-homomixer, 710 parts by mass of ion-exchanged water and 0.1 mol / L-Na_ThreePO_Four450 mass parts of aqueous solution was added, the rotation speed was adjusted to 7000 rpm, and it heated at 60 degreeC. Here 1.0 mol / L-CaCl₂Gradually add 68 parts by mass of an aqueous solution, and add a minute water-insoluble dispersant Ca_Three(PO_Four)₂An aqueous dispersion medium containing was prepared.
[0130]
on the other hand,
・ 80 parts by mass of styrene monomer
・ 20 parts by mass of 2-ethylhexyl acrylate monomer
・ Polyester 10 parts by mass
(Acid value 20 mg KOH / g, peak molecular weight 7500)
・ Carbon black (primary particle size 44nm) 10 parts by mass
・ Ester wax No. 4
(R₁, R₂: C₁₈H₃₇) 10 parts by mass
・ Monoazochrome complex 1 part by mass
After the above materials were sufficiently dispersed using a ball mill, the contents were isolated from the ball mill. A polymerizable monomer composition in which 3 parts by mass of 2,2′-azobis (2,4-dimethylbutyronitrile), which is a polymerization initiator, is added to the content is charged into the aqueous dispersion medium. The granulation was carried out while maintaining the rotational speed of 7000 rpm. Thereafter, the mixture was reacted at 60 ° C. for 4 hours while stirring with a paddle stirring blade, then polymerized at 80 ° C. for 5 hours, and further distilled under reduced pressure at 85 ° C. to complete the reaction.
[0131]
After completion of the reaction, the suspension is cooled, and hydrochloric acid is added to form a poorly water-soluble dispersant Ca._Three(PO_Four)₂After being dissolved, filtered, washed with water, and dried, it was classified to a desired particle size by air classification to obtain colored particles (1).
[0132]
Subsequently, the BET specific surface area is 130 mm with respect to 100 parts by mass of the colored particles.²The developer (1) of the present invention is prepared by charging 1.3 parts by mass of / g of hydrophobic silica into a Henschel mixer and subjecting the mixture to high-speed stirring at a strength equivalent to 1.5 times the normal processing conditions. did.
[0133]
The liberation rate of the surface metal oxide in the developer was measured with an asynchronous component of C-Si atoms and found to be 0.9%. Further, when the shape of the developer (1) was measured, the equivalent circle diameter was 6.6 μm, the average circularity was 0.980, the circularity standard deviation was 0.029, and the coarse particle amount in the Coulter Multisizer was It was 0.3% by volume.
[0134]
Developer production example (2)
Colored particles (2) were obtained in the same manner as in Developer Production Example (1) except that the colorants shown in Table 2 were used.
[0135]
Subsequently, the BET specific surface area is 130 mm with respect to 100 parts by mass of the colored particles.²/ G of hydrophobic silica 1.3 parts by weight and 0.5 parts by weight of anatase-type titanium oxide in a Henschel mixer and stirred at high speed with a strength equivalent to 1.5 times the normal processing conditions. The developer (2) of the present invention was prepared. The liberation rate of hydrophobic silica in this developer was 0.7%, and the liberation rate of titanium oxide was 0.5% as measured by an asynchronous component of C—Ti atoms. Further, when the shape of the developer (2) was measured, the average circularity was 0.980, the circularity standard deviation was 0.030, and the coarse particle amount in the Coulter Multisizer was 0.4% by volume. .
[0136]
Developer production examples (3), (4)
Developers (3) and (4) were obtained in the same manner as in Developer Production Example (1) except that the colorant shown in Table 2 was used.
[0137]
The liberation rate of hydrotalcite was measured with an asynchronous component of C-Mg atoms.
[0138]
Developer production example (5)
The colored particles were produced by the melt pulverization method shown below. As a specific production method, first, the following materials were mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.).
・ Styrene-butyl acrylate-maleic acid butyl half ester copolymer
(Peak molecular weight: about 40000, glass transition point Tg: 63 ° C.) 100 parts by mass
・ Carbon black (primary particle size 40nm) 10 parts by mass
・ 2 parts by weight of dicarboxylic acid aluminum complex
·polyethylene
(Molecular weight distribution = 1.08, DSC endothermic peak: 107 ° C.) 5 parts by mass
[0139]
Subsequently, a twin-screw kneader (PCM) is used so that the barrel set temperature at the kneading section on the rearmost side of the screw extrusion kneader becomes T0 (° C.) = 110 ° C. and the melt kneader outlet temperature T1 = 150 ° C. -30 type, manufactured by Ikekai Tekko Co., Ltd.). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a developer crushed material. Next, the coarsely crushed material was finely pulverized with a collision-type airflow pulverizer, and then subjected to spheronization treatment using a surface modification device utilizing mechanical impact force to obtain a spherical pulverized raw material. Next, the obtained pulverized raw material was introduced into a multi-division classifier elbow jet classifier (manufactured by Nippon Steel Mining) and classified so as to obtain a desired particle size distribution, whereby colored particles (5) were obtained.
[0140]
Subsequently, by subjecting 100 parts by weight of the colored particles (5) to 1.8 parts by weight of hydrophobic silica and 0.3 parts by weight of hydrotalcite, surface treatment is performed in the same manner as in Production Example (1). A developer (5) of the present invention was prepared. The liberation rate of hydrophobic silica in this developer was 6.5%, and the liberation rate of hydrotalcite was 0.3% as measured by an asynchronous component of C-Mg atoms.
[0141]
Further, when the shape of the developer (2) was measured, the average circularity was 0.976, the circularity standard deviation was 0.036, and the coarse particle amount in the Coulter Multisizer was 0.4% by volume. .
[0142]
Developer production example (6)
A developer (6) was produced in the same manner as in the developer production example (5) except that only the formulation shown in Table 2 was changed.
[0143]
The liberation rate of hydrophobic silica in this developer was 8.1%, and the liberation rate of polymethyl methacrylate was not measurable.
[0144]
Developer production example (7)
Developer production example (5) except that in the developer production example (5), the step of performing the spheronization treatment using a surface modifying apparatus utilizing mechanical impact force is omitted and the classification conditions are operated. A developer (7) was produced in the same manner as described above.
[0145]
Further, when the shape of the developer (7) was measured, the average circularity was 0.952, the circularity standard deviation was 0.042, and the coarse particle amount in the Coulter Multisizer was 1.4% by volume. .
[0146]
Comparative developer example (1)
Using the colored particles (1) obtained in Developer Production Example (1), positively charged polystyrene particles having an average particle diameter of 0.3 μm as surface fine particles were externally added, and Comparative Developer (1) was added. Manufactured. When the shape of the comparative developer (1) obtained was measured, the average circularity was 0.980, the circularity standard deviation was 0.029, and the coarse particle amount in the Coulter Multisizer was 0.5% by volume. there were.
[0147]
Comparative production example of developer (2)
In the developer production example (7), the developer classification conditions were adjusted so that the amount of coarse particles was adjusted to 1.6% by volume, except that the surface treatment was carried out using 1.5 parts by mass of hydrophobic silica. Comparative developer (2) was prepared in the same manner as in developer production example (7).
[0148]
Comparative production example of developer (3)
In the developer production example (7), the developer classification conditions were adjusted so that the amount of coarse particles was 1.6% by volume. With respect to 2.5 parts by mass of hydrophobic silica and 0.2% of polymethyl methacrylate. A comparative developer (3) of the present invention was prepared by adding parts by weight and subjecting the mixture to high-speed stirring with a Henschel mixer under normal processing conditions.
[0149]
The developers synthesized above are summarized in Table 2.
[0150]
[Table 2]

[0151]
Example (1)
Next, the developing device used in this embodiment will be specifically described.
[0152]
FIG. 1 is a schematic diagram of a modified 600 dpi laser beam printer (Canon: LBP-860) using the one-component contact developing type electrophotographic process used in this example. In this example, an apparatus in which the following parts (a) to (h) were modified was used.
(A) The process speed was changed to 94 mm / s.
(B) The charging method of the apparatus was direct charging by contact with a rubber roller, and the applied voltage was a DC component.
(C) Medium resistance rubber roller (16φ, hardness ASKER C45 degree, resistance 10) made of silicone rubber in which carbon black is dispersed as a developer carrier.^Five(Ω · cm, Ra = 2.1 μm, Rz = 3.5 μm), and arranged so as to be in pressure contact with the electrostatic latent image carrier with a nip width of 3.0 mm.
(D) The rotational peripheral speed of the developer carrying member is a forward direction at the contact portion with the electrostatic latent image carrying member, and the relative speed of the electrostatic latent image carrying member with respect to the developer carrying member is 155%. The speed was adjusted.
(E) The latent electrostatic image bearing member is an organic latent electrostatic image bearing member, and a voltage obtained by mixing alternating current and direct current is applied by a roller-type contact charging member to uniformize the surface potential of the latent electrostatic image bearing member. It shall be charged.
(F) The developer supply peeling member (1) was used as the developer supply peeling member. Further, the distance between the shafts was adjusted so that the developer supply / peeling member and the developer carrying member had an intrusion amount of 2 mm. Further, the rotation direction and the rotation speed were set so that these relative speeds were 90% at the opposite side.
(G) A blade obtained by dipping a solvent-diluted urethane on a phosphor bronze surface having a thickness of 0.5 mm so that the contact pressure with the developer carrier is about 29.6 N / m (about 30 g / cm). Installed on.
(H) Only the DC component was applied during development.
(J) The cleaning blade on the electrostatic latent image carrier was attached so that the contact pressure was about 39.2 N / m (about 40 g / cm).
[0153]
The electrophotographic apparatus was remodeled and process conditions were set as follows in order to conform to the remodeling of these process cartridges.
[0154]
The modified device uses a roller charger to uniformly charge the image carrier. After charging, an image portion is exposed with a laser beam to form an electrostatic latent image, and after making a visible image with a developer, the developer image is transferred to a transfer material by a roller to which a voltage of +700 V is applied. . The outline is shown in FIG.
[0155]
Using the above image forming method, using developer (1) as a developer, an A4 image having a printing rate of 3% under an environment where the temperature and humidity are 25 ° C. and 10%, and 30 ° C. and 50%. Was output continuously 5000 sheets. Thereafter, an image described later was sampled as an evaluation image, and the obtained image was evaluated. The evaluation results are summarized in Table 3.
[0156]
  Examples (2) to (6), Reference Example (1), and Comparative Examples (1) to (3)
  Using the image forming apparatus used in Example (1) and using Developers (2) to (7) and Comparative Examples (1) to (3) as developers, the same as in Example (1). Images were output and the resulting images were evaluated.
[0157]
  Here, Examples (1) to (6)Reference example (1)However, this is because the liberation rate of the metal oxide fine particles in the developer is in an appropriate range, and the amount of coarse particles in the developer is in a good range. As a result of the invention, sufficient supply of developer and sufficient stripping performance could be maintained, and the effects of development problems caused by coarse particles and free external additives were kept as much as possible. It is possible to form a stable image with excellent properties.
[0158]
Further, in Examples (1) to (5), it was revealed that the effect of the present invention appears more remarkably when the particle shape of the developer is appropriate. This is because when the particle shape of the developer is in the range of the present invention, the amount of the developer entering the cell inside the open-cell developer supply / peeling member is appropriate, and the shape distribution is spherical. This is because the developer discharge performance is good due to the closeness to the above, and thus the desired amount of developer is supplied without any problem. Further, the developer discharge performance is excellent in this manner, so that the cells on the surface of the developer supply / peel member are always exposed, and as a result, the residual developer after development on the developer carrier is peeled off. Ability can be maintained at all times. Therefore, the combination of the developer shape and the developer supply / peeling member means that the durable developer supply and developer stripping are performed well.
[0159]
In addition, the developer does not fuse the developer to the surface of the regulating member or the electrostatic latent image carrier during durability, despite the endurance test under harsh environments such as low humidity and high temperature. In addition, even in the second half of the endurance, stable performance that is the same as the initial stage can be demonstrated. It is not clear about the mechanism in which such an effect is manifested. However, when the development is repeated, the developer having a release rate of metal oxide fine particles in the developer of 0.01 to 10% is a developer. This is considered to be because it is possible to improve the charging uniformity of the developer in order to make it difficult to generate the accumulation of free metal oxide fine particles in the cells of the supply peeling member.
[0160]
Examples (8) and (9) and comparative examples (4) to (7)
The developer (1) is used as the developer, and the developer supply / peeling member of the developing device used in Example (1) as the image forming apparatus is used as the developer supply / peeling member production examples (2) to (3) Images were output in the same manner as in Example (1) except that the developer supply / peeling member was changed to Comparative Production Examples (1) to (4), and the obtained images were evaluated.
[0161]
FIG. 4 illustrates the fur brush type image forming method used in Comparative Production Example (4).
[0162]
In the results of Examples (8) and (9) and Comparative Examples (4) to (7), the production systems (2) and (3) of the developer peeling supply member showed stable development performance. Among them, the production examples (2) and (3) of the developer peeling supply member showed good performance. This is because the number of cells of the developer peeling supply member is in an appropriate range. It is considered that free particles in the particles and external additives are trapped in the open cell and are not involved in development.
[0163]
Table 3 summarizes the printout evaluation results of Examples (1) to (9) and Comparative Examples (1) to (7). (Details of evaluation will be described later)
[0164]
[Table 3]

[0165]
Example (10)
Using the full-color image forming apparatus shown in FIG. 2, full-color image formation was attempted. First, developer (1), developer (2), developer (3), and developer (4) were introduced into developing devices 4-1, 4-2, 4-3, and 4-4. Next, the electrostatic latent image on the electrostatic latent image carrier 1 is developed by the developing device 4-1.
[0166]
The visualized toner image on the electrostatic latent image carrier 1 is applied to a primary transfer voltage (for example, ±±) on an intermediate transfer member 5 disposed in contact with the lower surface of the electrostatic latent image carrier 1. (0.1 ±± 5 kV). At this time, the detachable cleaning unit 10 is detached from the intermediate transfer member 5, whereby the toner image visualized by the developing device 4-1 is held on the intermediate transfer member 5.
[0167]
Subsequently, the developing devices 4-2, 4-3, and 4-4 are sequentially developed by the same method so that the toner images of the first color, the second color, the third color, and the fourth color are superimposed on the intermediate transfer member 5. In addition, these toner images are collectively transferred onto the transfer material 6 by a transfer voltage (for example, ± 0.5 to ± 10 kV) with the transfer roller 7 via the transfer material 6 disposed on the outer surface of the intermediate transfer member 5. Transcribed. After the transfer of the toner image to the transfer material 6, the surface of the intermediate transfer member 5 is cleaned by a removable cleaning means 10.
[0168]
Subsequently, the toner image on the transfer material 6 is fixed by the heat and pressure fixing means H to obtain a permanent image.
[0169]
Using this image forming apparatus, a full-color image having a printing rate of 3% under a 23 ° C., 40% and 50% environment was continuously subjected to a durability test of 4000 sheets. As a result, a stable color image having excellent development streaks, uneven development, and image density followability and no development streaks was obtained.
[0170]
Description of the evaluation items described in Examples 1 to 9 and Comparative Examples 1 to 7 and the evaluation criteria thereof will be described.
[0171]
The evaluation items used in this example will be described.
[0172]
[Printout image evaluation]
<1> Development stripe
After durability at an image density of 3% in a low humidity environment (25 ° C., 10%) and a high temperature environment (30 ° C., 50%), 30% of 600 dpi The development streak was visually evaluated on the image obtained by outputting the halftone image of the printing rate.
A: Very good (good)
B: Good (almost unacceptable level)
C: Practical use possible (Some levels are not problematic for practical use)
D: Practical difficulty (Streak can be confirmed and in some cases it becomes a problem)
E: Not practical (streaks are very conspicuous and cause practical problems)
[0173]
<2> Development unevenness
After durability at an image density of 3% in a low humidity environment (25 ° C., 10%) and a high temperature environment (30 ° C., 50%), 30% of 600 dpi Development unevenness was visually evaluated for an image obtained by outputting a halftone image having a printing rate.
A: Very good (good)
B: Good (almost unacceptable level)
C: Practical use possible (Some levels are not problematic for practical use)
D: Practical difficulty (Hayaya can be confirmed, sometimes problematic)
E: Not practical (Haya is very conspicuous and causes practical problems)
[0174]
<3> Image density
Ordinary paper for ordinary copying machines (75 g / m²), The difference between the image density in the vicinity of the tip and the image density in the vicinity of the tip and the middle and subsequent stages was evaluated for the image density when a predetermined number of printouts were completed, and these two points were evaluated according to the following criteria. In addition, the evaluation was made by the A-E rank from the image density and the density difference that satisfy both.
[0175]
The image density was measured by using a “Macbeth reflection densitometer” (manufactured by Macbeth Co., Ltd.) to measure a relative density with respect to a printout image of a white background portion having a document density of 0.00.
A: The tip concentration is 1.40 or more and the concentration difference is less than 0.1.
B: The tip concentration is 1.35 or more and less than 1.40, and the concentration difference is 0.1 or more and less than 0.2.
C: The tip concentration is 1.25 or more and less than 1.35, and the concentration difference is 0.2 or more and less than 0.4.
D: The tip density is 1.00 or more and less than 1.25, and the density difference is 0.4 or more and less than 0.6.
E: The tip concentration is less than 1.00 and the concentration difference is 0.6 or more
[0176]
【The invention's effect】
As described above, according to the present invention, in the one-component contact development system, in the matching of the developer supply peeling member and the developer, a sufficient supply force of the developer and a sufficient stripping performance are maintained, and the image A developer having a stable density and an image forming method are obtained. In addition, it is possible to provide an image forming method in which the influence of development problems caused by coarse particles in the developer and free external additives is suppressed as much as possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming method preferably used in the present invention.
FIG. 2 is an example of a full-color image forming method having an intermediate transfer member preferably used in the present invention.
FIG. 3 is an image diagram of open bubbles and single bubbles of a developer supply / peeling member;
FIG. 4 is a fur brush type image forming method used in Comparative Example (7).
[Explanation of symbols]
1 Photoconductor
2 Charging roller
3 Laser light
4-1 Yellow developer
4-2 Magenta developer
4-3 Cyan developer
4-4 Black developer
5 Intermediate transfer drum
6 Transfer material
7 Transfer roller
8 Cleaner (photosensitive drum cleaner)
10 Cleaner (Cleaner for intermediate transfer drum)
100 Developer carrier
111 Fur Brush Type Developer Supply Peeling Unit
127 Transfer material (recording material)
100 Electrostatic latent image carrier (photosensitive drum)
117 Charging device (charging roller)
140 Developer

Claims (2)

In a non-magnetic one-component contact image forming method having a developer supply peeling member arranged so as to come into pressure contact with a developer carrying member,
The developer supply release member is an open-cell foamed elastic body having 50 to 150 cells per 25 mm,
The developer is a non-magnetic one-component developer having at least a binder resin, colored particles composed of a colorant and a release agent, and at least metal oxide fine particles on the surface of the colored particles. free of the metal oxide fine particles comprising 0.01 to 10%, and coarse particles (above 12.7 [mu] m) in the developer amount Ri der than 1.5 vol%,
In the developer-based circle equivalent diameter-circularity scattergram measured by the flow type particle image measuring apparatus, the average circularity of the developer is 0.950 to 0.990, and the circularity standard deviation is 0. An image forming method, wherein the image forming method is less than 040 . 2. The developer carrying member according to claim 1 , wherein the developer carrying member has an elastic member on a surface thereof, and has a surface roughness Ra of 0.2 to 5.0 μm and an Rz of 8.0 μm or less. Image forming method.

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