JP2005003838A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method by which high-grade images are stably and continuously provided without causing image defects even in a high-speed process, as an image forming method which uses a developing device adopting a so-called trickle developing system and in which a residual toner recovered by a cleaning means from the surface of an electrostatic latent image carrier is returned to the inside of a development section or a toner replenishment section through a toner recovery device and reused as a recycled toner, and to provide an image forming method in which cleaning properties by a cleaning means are stabilized and properties as an electrostatic latent image carrier can be maintained over a prolonged period of time. <P>SOLUTION: In the image forming method for performing image formation with an image forming apparatus including a charging means, an electrostatic latent image forming device, a developing device, a transfer means, a cleaning means and a fixing device, the developing device properly replenishes a developer for replenishment containing a toner and a carrier to the inside of a developing vessel and includes a developer recovery mechanism for recovering an excess of the developer from the inside of the developing vessel, a toner recovered from an electrostatic latent image carrier is reused as a recycled toner, and a percentage of the recycled toner in the whole quantity of a replenished toner replenished to a developer is ≥15 mass%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１０４】
一般式（ＩＩ）中、Ａｒ_１〜Ａｒ_４は、それぞれ独立に置換又は未置換のアリール基を表し、Ａｒ_５は、置換若しくは未置換のアリール基又はアリーレン基を表す。但し、Ａｒ_１〜Ａｒ_５のうち１〜４個は、Ｆ、Ｄ、及びＡを含む化合物中の−Ｄ−Ａで表される結合基と結合可能な結合手を有する。ｋは０または１を表す。
【０１０５】
【化２】

【０１０６】
上記中、Ａｒは下記構造群２に挙げられるものが好ましい。
【０１０７】
【化３】

【０１０８】
また、前記Ｚ’は下記構造群３に挙げられるものが好ましい。
【０１０９】
【化４】

【０１１０】
ここで、Ｒ_６ は、水素、炭素数１〜４のアルキル基、炭素数１〜４のアルキル基もしくは炭素数１〜４のアルコキシ基で置換されたフェニル基、または未置換のフェニル基、炭素数７〜１０のアラルキル基を表す。Ｒ_７〜Ｒ_１３は、水素、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、もしくは炭素数１〜４のアルコキシ基で置換されたフェニル基、または未置換のフェニル基、炭素数７〜１０のアラルキル基、ハロゲンを表す。ｍ及びｓはそれぞれ独立に０または１を表し、ｑ及びｒはそれぞれ独立に１〜１０の整数、ｔ、ｔ’はそれぞれ独立に１〜３の整数を表す。ここで、Ｘは前記−Ｄ−Ａと同様である。
【０１１１】
また、前記Ｗは下記に構造群４に挙げられるものが好ましい。
【０１１２】
【化５】

【０１１３】
ここで、ｓ’は０〜３の整数を表す。
【０１１４】
一般式（ＩＩ）におけるＡｒ_５の具体的構造としては、ｋ＝０ の時は、上記Ａｒ_１〜Ａｒ_４のｍ＝１の構造が、ｋ＝１ の時の時は、上記Ａｒ_１〜Ａｒ_４のｍ＝０の構造が挙げられる。
【０１１５】
前記Ｆ、Ｄ、及びＡを含む光機能性有機けい素化合物は、１種単独で使用してもよいし、２種以上併用してもよい。
表面層形成に際しては、硬化膜の機械的強度をさらに向上させる目的で、前記Ｆ、Ｄ、及びＡを含む化合物と結合可能な基を有する化合物の少なくとも１種を添加することが好ましい。
【０１１６】
上記Ｆ、Ｄ、及びＡを含む化合物と結合可能な基とは、該Ｆ、Ｄ、及びＡを含む化合物を加水分解した際に生じるシラノール基と結合可能な基を意味し、具体的には、−Ｓｉ（Ｒ_１）_{（３−ａ）}Ｑ_ａで示される基、エポキシ基、イソシアネート基、カルボキシル基、ヒドロキシ基、ハロゲンなどを意味する。これらのうち、−Ｓｉ（Ｒ_１）_{（３−ａ）}Ｑ_ａで示される加水分解性基、エポキシ基、イソシアネート基を有する化合物が、より強い機械的強度を有するため好ましい。
【０１１７】
さらに、Ｆ、Ｄ、及びＡを含む化合物と結合可能な基を有する化合物としては、これらの基を分子内に２つ以上持つものが、硬化膜の架橋構造を３次元的にし、膜により強い機械的強度を与えるため好ましい。これらのうち、最も好ましい化合物例として一般式（ＩＩＩ）で示される化合物が挙げられる。
【０１１８】
【化６】

【０１１９】
一般式（ＩＩＩ）中、Ａ’は−Ｓｉ（Ｒ_１）_{（３−ａ）}Ｑ_ａで表される加水分解性基を有する置換けい素基、Ｂは枝分かれを含んでも良いｎ価の炭化水素基、ｎ価のフェニル基、−ＮＨ−、−Ｏ−Ｓｉ−から選ばれる基の少なくとも１つ、あるいはこれらの組み合わせから構成される。ａは１〜３の整数、ｎは２以上の整数を表す。
【０１２０】
一般式（ＩＩＩ）で示される化合物は、−Ｓｉ（Ｒ_１）_{（３−ａ）}Ｑ_ａで表される加水分解性基を有する置換けい素基Ａ’を２個以上有している化合物である。Ａ’に含まれるＳｉ基の部分が、前記Ｆ、Ｄ、及びＡを含む化合物あるいは化合物（ＩＩＩ）自身と反応し、Ｓｉ−Ｏ−Ｓｉ結合となって３次元的な架橋硬化膜を形成していく。Ｆ、Ｄ、及びＡを含む化合物も同様のＳｉ基を有しているので、それのみで硬化膜を形成することも可能であるが、化合物（ＩＩＩ）は２個以上のＡ’を有しているので硬化膜の架橋構造が３次元的になり、より強い機械的強度を有するようになると考えられる。また、Ｆ、Ｄ、及びＡを含む化合物におけるＤ部分と同様、架橋硬化膜に適度な可とう性を与える役割もある。
化合物（ＩＩＩ）としては、下記構造群５に示されるものがより好ましい。
【０１２１】
【化７】

【０１２２】
上記式中、Ｔ_１、Ｔ_２はそれぞれ独立に枝分かれしていてもよい２価あるいは３価の炭化水素基、Ａ’は前記した置換基を表わす。ｈ、ｉ、ｊは１〜３の整数であり、かつ、分子内のＡ’の数が２以上となるように選ばれる。
【０１２３】
これらの式で表わされる一般式（ＩＩＩ）の化合物の具体例を以下に示すが、これらに限定されるわけではない。
【０１２４】
【化８】

【０１２５】
前記Ｆ、Ｄ及びＡからなる光機能性有機けい素化合物は、１種単独で使用してもよいし、２種以上併用してもよい。また、膜の成膜性、可とう性を調整するなどの目的から、他のカップリング剤、フッ素化合物などを混合して用いてもよい。このような化合物として、各種シランカップリング剤、および市販のシリコーン系ハードコート剤を用いることができる。
また、表面保護層として架橋膜を形成する場合は、有機金属化合物、あるいは硬化型マトリックスを添加することが好ましい。
【０１２６】
これらのコーティング液の調製は、無溶媒で行うか、必要に応じてメタノール、エタノール、プロパノール、ブタノール等のアルコール類；アセトン、メチルエチルケトン等のケトン類；テトラヒドロフラン、ジエチルエーテル、ジオキサン等のエーテル類等が使用できるが、好ましくは沸点が１００℃以下のものであり、任意に混合しての使用もできる。溶剤量は任意に設定できるが、少なすぎると前記Ｆ、Ｄ、及びＡを含む化合物が析出しやすくなるため、前記Ｆ、Ｄ、及びＡを含む化合物１質量部に対し０．５〜３０質量部、好ましくは１〜２０質量部で使用される。
【０１２７】
コーティング液調製においては、前記Ｆ、Ｄ、及びＡを含む化合物と、必要に応じてその他の化合物と、を固体触媒に接触させて反応させるが、反応温度および時間は原料の種類によっても異なり、通常は０〜１００℃で行われ、０〜７０℃で行うことがより好ましく、１０〜３５℃の温度で行うことが特に好ましい。反応時間に特に制限はないが、反応時間が長くなるとゲル化を生じ易くなるため、１０分から１００時間の範囲で行うことが好ましい。
【０１２８】
前記Ｆ、Ｄ、及びＡからなる化合物と結合可能な基を有するポリマーを添加する場合、固体触媒と上記ポリマーとが同時に存在すると著しくゲル化を促進し、コーティングが困難となる場合があるため、固体触媒を除去した後に添加することが好ましい。このような固体触媒は、触媒成分が前記Ｆ、Ｄ、及びＡを含む化合物溶液、その他の化合物、溶媒等のいずれにも不溶であるものであれば、特に限定されない。
【０１２９】
加水分解縮合させる際の水の添加量は、特に限定されないが、生成物の保存安定性やさらに重合に供する際のゲル化抑制に影響するため、好ましくは、前記Ｆ、Ｄ、及びＡを含む化合物の加水分解性基をすべて加水分解するに必要な理論量に対して３０〜５００％、さらに５０〜３００％の範囲の割合で使用することが好ましい。水の量が５００％よりも多い場合、生成物の保存安定性が悪くなったり、析出しやすくなる。一方、水の量が３０％より少ない場合、未反応物が増大してコーティング液塗布時、硬化時に相分離を起こしたり、塗膜の強度低下を起こしやすい。
【０１３０】
さらに硬化触媒として、塩酸、酢酸、リン酸、硫酸などのプロトン酸等を加え硬化させる。硬化温度は、任意に設定できるが、所望の強度を得るためには６０℃以上、より好ましくは８０℃以上に設定される。硬化時間は、必要に応じて任意に設定できるが、１０分〜５時間が好ましい。また、硬化反応を行ったのち、高湿度状態に保ち、特性の安定化を図ることも有効である。さらに、用途によっては、ヘキサメチルジシラザンや、トリメチルクロロシランなどを用いて表面処理を行い、疎水化することもできる。
【０１３１】
塗布方法としては、ブレードコーティング法、ワイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法等の通常の方法を用いることができる。
【０１３２】
本発明に用いられる感光体においては、所望により基材（導電性支持体）と感光層の間に下引き層を形成することもできる。下引き層を形成するために用いられる材料としては、従来より下引き層に用いられている公知の結着樹脂を用いることができるが、前記の表面層を構成する材料によっても形成することができる。この場合、所望により、ジルコニウム系化合物、電子輸送性顔料等の他の材料を添加してもよい。
【０１３３】
本発明に用いられる感光体において、前記表面保護層を設けた場合、その下層に形成される感光層は、従来から公知のあらゆる感光体の感光層を採用することができ、電荷発生層と電荷輸送層とを積層した積層型の感光体でもよいし、電荷発生材料を含有する単層型感光体でもよいが、感度、耐久性等の観点から、積層型の感光体が好ましい。
【０１３４】
積層型の感光層における電荷発生層は、少なくとも電荷発生材料及び結着樹脂から形成される。
電荷発生材料は、ビスアゾ、トリスアゾなどのアゾ顔料、ジブロモアントアントロンなどの縮環芳香族顔料、ペリレン顔料、ピロロピロール顔料、フラトシアニン顔料等既知のもの全て使用することができるが、特に金属及び無金属フタロシアニン顔料が好ましい。その中でも、特定の結晶を有するヒドロキシガリウムフタロシアニン、クロロガリウムフタロシアニン、ジクロロスズフタロシアニン、チタニルフタロシアニンが特に好ましい。また、結着樹脂は、広範な絶縁性樹脂の中から選択することができる。
電荷発生材料と結着樹脂との配合比は（質量比）、１０：１〜１：１０の範囲が好ましい。
【０１３５】
これらを分散させる方法としては、ボールミル分散法、アトライター分散法、サンドミル分散法等の通常の方法を用いることができるが、この際、分散によって、電荷発生材料の結晶型が変化しないことが必要とされる。
上記分散には、メタノール、エタノール、ｎ−プロパノール、ｎ−ブタノール、ベンジルアルコール、メチルセルソルブ、エチルセルソルブ、アセトン、メチルエチルケトン、シクロヘキサノン、酢酸メチル、酢酸ｎ−ブチル、ジオキサン、テトラヒドロフラン、メチレンクロライド、クロロホルム、クロルベンゼン、トルエン等の通常の有機溶剤を、単独あるいは２種以上混合して用いることができる。
【０１３６】
電荷発生層の厚みは、一般的には０．１〜５μｍ、好ましくは０．２〜２．０μｍである。また、電荷発生層を設けるときに用いる塗布方法としては、ブレードコーティング法、ワイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法等の通常の方法を用いることができる。
【０１３７】
本発明に用いられる感光体における電荷輸送層としては、公知の技術によって形成されたものを使用できる。それらの電荷輸送層は、電荷輸送材料と結着樹脂とを含有して形成されるか、あるいは高分子電荷輸送材を含有して形成される。
電荷輸送材料としては、ｐ−ベンゾキノン、クロラニル、ブロマニル、アントラキノン等のキノン系化合物、テトラシアノキノジメタン系化合物、２，４，７−トリニトロフルオレノン等のフルオレノン化合物、キサントン系化合物、ベンゾフェノン系化合物、シアノビニル系化合物、エチレン系化合物等の電子輸送性化合物；トリアリールアミン系化合物、ベンジジン系化合物、アリールアルカン系化合物、アリール置換エチレン系化合物、スチルベン系化合物、アントラセン系化合物、ヒドラゾン系化合物などの正孔輸送性化合物；が挙げられる。これらの電荷輸送材料は、単独または２種以上混合して用いることができるが、これらに限定されるものではない。
【０１３８】
電荷輸送材料としては、一般式（ＩＶ）で表わされるトリフェニルアミン系化合物、及び一般式（Ｖ）で表わされるベンジジン系化合物が、高い電荷（正孔）輸送能と優れた安定性を有しているため、特に好ましく用いられる。
【０１３９】
【化９】

【０１４０】
上記式中、Ｒ_１４は、水素原子またはメチル基を表す。また、ｎは１または２である。Ａｒ_６及びＡｒ_７はそれぞれ独立に置換または未置換のアリール基を表し、置換基としてはハロゲン原子、炭素数が１〜５の範囲のアルキル基、炭素数が１〜５の範囲のアルコキシ基、または炭素数が１〜３の範囲のアルキル基で置換された置換アミノ基を表す。
【０１４１】
【化１０】

【０１４２】
上記式中Ｒ_１５、Ｒ_１５′ はそれぞれ独立に、水素原子、ハロゲン原子、炭素数１〜５のアルキル基、炭素数１〜５のアルコキシ基、を表す。Ｒ_１６、Ｒ_１６′、Ｒ_１７、Ｒ_１７′ はそれぞれ独立に、水素原子、ハロゲン原子、炭素数１〜５のアルキル基、炭素数１〜５のアルコキシ基、炭素数１〜２のアルキル基で置換されたアミノ基を表す。ｍ及びｎはそれぞれ独立に０〜２の整数である。
これらは、単独または２種以上混合して用いることができる。また、高分子電荷輸送材を用いることもできる。
【０１４３】
電荷輸送層に用いる結着樹脂としては、ポリカーボネート樹脂、ポリエステル樹脂、メタクリル樹脂、アクリル樹脂、ポリ塩化ビニル樹脂、ポリ塩化ビニリデン樹脂、ポリスチレン樹脂、ポリビニルアセテート樹脂、スチレン−ブタジエン共重合体、塩化ビニリデン−アクリロニトリル共重合体、塩化ビニル−酢酸ビニル共重合体、塩化ビニル−酢酸ビニル−無水マレイン酸共重合体、シリコーン樹脂、シリコーン−アルキッド樹脂、フェノール−ホルムアルデヒド樹脂、スチレン−アルキッド樹脂等を挙げることができる。
【０１４４】
前記結着樹脂は単独あるいは２種以上混合して用いることができる。電荷輸送材料と結着樹脂との配合比（質量比）は１０：１〜１：５の範囲が好ましい。電荷輸送層の厚みは５〜５０μｍの範囲が好ましく、１０〜３０μｍの範囲がより好ましい。塗布方法としては、ブレードコーティング法、ワイヤーバーコーティング法、スプレーコーティング法、浸漬コーティング法、ビードコーティング法、エアーナイフコーティング法、カーテンコーティング法等の通常の方法を用いることができる。
【０１４５】
さらに溶剤としては、ベンゼン、トルエン、キシレン、クロルベンゼン等の芳香族炭化水素類；アセトン、２−ブタノン等のケトン類；塩化メチレン、クロロホルム、塩化エチレン等のハロゲン化脂肪族炭化水素類；テトラヒドロフラン、エチルエーテル等の環状もしくは直鎖状のエーテル類；等の通常の有機溶剤を単独あるいは２種以上混合して用いることができる。
【０１４６】
前記導電性支持体としては、一般にアルミニウムがドラム状、シート状、プレート状等、適宜の形状のものとして使用されるが、これらに限定されるものではない。感光体ドラムがレーザープリンターに使用される場合には、レーザー光を照射する際に生じる干渉縞を防止するために、支持体表面は、中心線平均粗さＲ_ａ７５値で０．０４μｍ〜０．５μｍの範囲となるように粗面化することが好ましい。粗面化の方法としては、研磨剤を水に懸濁させて支持体に吹き付けることによって行う湿式ホーニング、あるいは、回転する砥石に支持体を圧接し、連続的に研削加工を行うセンタレス研削が好ましい。Ｒ_ａ７５値が０．０４μｍより小さいと、鏡面に近くなるので干渉防止効果が得られなくなり、Ｒ_ａ７５値が０．５μｍより大きいと、下引き層として被膜を形成しても画質が粗くなって不適である。非干渉光を光源に用いる場合には、干渉縞防止の粗面化は特に必要なく、基材の表面の凹凸による欠陥の発生が防げるため、より長寿命化に適する。
【０１４７】
なお、本発明に用いられる感光体において、表面保護層を設けない場合には、導電性支持体表面に形成された感光層の最表面層が、本発明に用いられる感光体の表面層となる。そして感光層としては、積層型および単層型の２通りがある。
【０１４８】
積層型の感光層の場合、電荷輸送層が表面であれば電荷輸送層が、電荷発生層が表面であれば電荷発生層が表面層となる。この場合、最表面層に、前記電荷輸送層あるいは電荷発生層の構成に代えて、前記、表面層として説明した層の構成が採用され、他の層は、前記説明した構成がそのまま採用される。
【０１４９】
一方、単層型感光層の場合には、当該感光層自体が前記表面層の構成を為す層となる。但し、当該単層型感光層中には、電荷発生材料を添加することが必要となる。電荷発生材料としては、前記説明した電荷発生層の場合と同様の材料を用いることができる。
【０１５０】
＜画像形成装置＞
本発明の画像形成方法においては、少なくとも、静電潜像担持体表面を帯電する帯電手段と、帯電された前記静電潜像担持体表面に静電潜像を形成する静電潜像形成手段と、該静電潜像を現像剤を用いてトナー画像として現像する現像手段と、前記トナー画像を被転写体に転写する転写手段と、転写後に静電潜像担持体表面に残留したトナーを除くクリーニング手段と、転写されたトナー画像を記録媒体に定着する定着手段と、を有する画像形成装置が用いられる
【０１５１】
本発明においては、前記現像手段が、現像器の内部に前記トナーおよびキャリアからなる補給用現像剤を適宜補給するとともに、過剰となった前記現像剤を内部から回収する現像剤回収機構を有する、すなわちトリクル現像方式を採用している。トリクル現像方式を採用する現像手段は、少なくとも１つあれば、現像剤のメンテナンスを省力化、さらにはメンテナンスフリーが実現できるが、勿論、より多くの現像手段について、トリクル現像方式を採用することが望ましく、全ての現像手段について採用することが最も望ましい。
【０１５２】
トリクル現像方式における補給用現像剤は、通常現像剤中に混入されるため、トナー消費に伴い一定量のずつ補給されることとなる。さらに、その一般的な制御方法としては、現像器内のトナー濃度センサーによりトナー濃度が一定範囲になるように逐次補給用現像剤が補給制御されるものが挙げられる。また、補給により過剰となった現像器内の現像剤は、通常オーバーフローにより回収され、回収容器に収容される。
【０１５３】
また、本発明の画像形成方法において、フルカラー画像を作成する場合には、用紙汎用性、高画質の観点から、各色のカラートナー画像を、被転写体としての中間転写ベルトまたは中間転写ドラム表面に一旦転写して積層させた後、該積層されたカラートナー画像を一度に紙等の記録媒体表面に転写することが好ましい。勿論、被転写体を紙等の記録媒体とし、直接、各色のカラートナー画像を積層する構成としてもよい。
【０１５４】
本発明の画像形成方法は、前述のように、高速プロセスの画像形成装置において有効にその効果が発揮される。本発明が適用可能なプロセススピードとしては、１００〜３５０ｍｍ／ｓｅｃの範囲であることが好ましく、１６０〜２８０ｍｍ／ｓｅｃの範囲であることがより好ましい。
【０１５５】
前記クリーニング手段とは、転写後の静電潜像担持体表面に、転写残として残った残留トナーを除去する手段である。このクリーニング手段により、ブレード、ブラシ、ロール等を静電潜像担持体表面に直接接触させ、静電潜像担持体表面に付着しているトナー、紙粉、ゴミなどを除去することができる。
【０１５６】
最も一般的に採用されているクリーニング手段として、ポリウレタン等のゴム製のブレードを静電潜像担持体に圧接させるクリーニングブレードである。これに対し、内部に磁石を固定配置し、その外周に回転可能な円筒状の非磁性体のスリーブを設け、そのスリーブ表面に磁性キャリアを担持させてトナーを回収する磁気ブラシや、半導電性の樹脂繊維や動物の毛をロール状に回転可能にし、トナーと反対極性のバイアスをそのロールに印加してトナーを除去する静電ブラシでもよい。
本発明においては、トナーリサイクルを行うため、クリーニングブレードが好ましく用いられる。
【０１５７】
本発明に用いられる画像形成装置においては、さらに、リサイクル手段が含まれる。該リサイクル手段は、前記クリーニング手段により回収したトナーを現像剤担持体を有する現像器等に移す手段である。
このリサイクル手段を有する態様の本発明の画像形成方法は、トナーリサイクルシステムタイプのコピー機、プリンタ、ファクシミリ機等の画像形成装置を用いて実施することができる。
【０１５８】
【実施例】
以下、実施例により本発明をさらに具体的に説明するが、本発明はこれらに限定されるものではない。なお、トナー、キャリアの説明において、特に断りのない限り、「部」は全て「質量部」を意味する。
【０１５９】
まず、実施例、比較例において使用したトナー、キャリア、及び現像剤について説明する。
＜各測定方法＞
下記トナー、キャリヤ、及び現像剤の製造において、各測定は以下の方法で行った。
【０１６０】
（外添剤、キャリアの体積固有抵抗値測定）
図１に示されるように、測定試料３を下部電極４と上部電極２とで挟持し、上方より加圧しながらダイヤルゲージで厚みＬを測定し、測定試料３の電気抵抗を高電圧抵抗計６で計測した。
【０１６１】
具体的には、外添剤としての特定酸化チタンの試料に、成形機にて４．９×１０^７Ｐａの圧力を加えて測定ディスクを作製した。次いで、測定ディスクの表面をハケで清掃し、セル内の上部電極２と下部電極４との間に挟み込み、ダイヤルゲージで厚みを測定した。次に電圧を印加し、電流値を読み取ることにより、体積固有抵抗値を求めた。
【０１６２】
また、キャリアの場合には、試料を直径１００ｍｍの下部電極４に充填し、上部電極２をセットし、その上から３．４３ｋｇの荷重を加え、ダイヤルゲージで厚みＬを測定した。次に電圧を印加し、電流値を読み取ることにより、体積固有抵抗値を求めた。
【０１６３】
なお、体積固有抵抗値（Ω・ｃｍ）の計算式は、下式に示す通りである。
Ｒ＝α×Ｅ／（Ｉ−Ｉ_０ ）／Ｌ
上記式中、Ｒは体積固有抵抗値（Ω・ｃｍ）、Ｅは印加電圧（Ｖ）、Ｉは電流値（Ａ）、Ｉ_０は印加電圧０Ｖにおける電流値（Ａ）、Ｌは試料層の厚み（ｍｍ）をそれぞれ表す。また、αの係数は、電極板の面積（ｃｍ^２）を表す。
【０１６４】
（トナーの形状係数ＳＦ１）
本発明において、トナーの形状指数ＳＦ１とは、前記のように個々のトナー粒子について下記式で計算される値の平均値を意味する。
ＳＦ１＝（ＭＬ^２／Ａ）×（π／４）×１００
上式において、ＭＬはトナーの最大長、Ａはトナーの投影面積を表す。下記式で計算された値を意味し、真球の場合ＳＦ１＝１００となる。
【０１６５】
上記形状指数を求めるための具体的な手法としては、トナー画像を光学顕微鏡から画像解析装置（ＬＵＺＥＸ ＩＩＩ：（株）ニレコ製）に取り込み、円相当径を測定して、最大長および面積から、個々の粒子について上記式のＳＦ１の値を求めることにより行った。
【０１６６】
（トナー帯電量測定）
後述する実機評価試験におけるトナー帯電量は、現像器中のマグスリーブ上の現像剤を約２ｇ採取し、上記と同様、２５℃、５５％ＲＨの条件下で東芝社製ＴＢ２００にて測定した。なお、測定した各現像剤のトナー濃度は、いずれも約１０質量％であった。
【０１６７】
＜感光体Ａの製造＞
ＪＩＳ Ａ３００３合金よりなる直径８４ｍｍ、長さ３４０ｍｍの引き抜き管を用意し、センタレス研磨装置により研磨し、表面粗さが十点平均粗さＲｚで０．６μｍのシリンダーとした。洗浄工程として、このシリンダーを脱脂処理した後、２質量％水酸化ナトリウム溶液で１分間エッチング処理し、中和処理、更に純水洗浄を順に行った。
【０１６８】
次に、陽極酸化処理工程として、１０質量％硫酸溶液によりシリンダー表面に陽極酸化膜（電流密度：１．０Ａ／ｄｍ^２）を形成した。水洗後、８０℃の１質量％酢酸ニッケル溶液中に２０分間浸漬して封孔処理を行った。更に、純水洗浄、乾燥処理を行った。このようにして、アルミニウムシリンダー表面に、膜厚７μｍの陽極酸化膜を形成したアルミニウム基材（導電性支持体）を得た。
【０１６９】
Ｘ線回折スペクトルにおけるブラッグ角（２θ±０．２°）が、７．４°、１６．６°、２５．５°、２８．３°に強い回折ピークを持つクロロガリウムフタロシアニンの１部を、ポリビニルブチラール（エスレックＢＭ−Ｓ：積水化学社製）１部、および酢酸ｎ−ブチル１００部と混合し、ガラスビーズとともにペイントシェーカーで１時間処理して分散して塗布液を作製した。得られた塗布液を、前記アルミニウム基材の陽極酸化膜表面に浸漬コーティング法で塗布し、１００℃で１０分間加熱乾燥して、膜厚約０．１５μｍの電荷発生層を形成した。
【０１７０】
下記式（１）で示されるベンジジン化合物（式中Ｍｅはメチル基を表す）２部、及び下記式（２）を基本単位とする高分子化合物（粘度平均分子量：３９，０００）３部を、クロロベンゼン２０部に溶解させた塗布液を、前記電荷発生層表面に浸漬コーティング法で塗布し、１１０℃、４０分の加熱を行なって、膜厚２０μｍの電荷輸送層を形成した。
【０１７１】
【化１１】

【０１７２】
下記一般式（ＩＩ）に示す化合物の中で、各置換基が表１に示される構造（表中、ｉＰｒはイソプロピル基を表す）である化合物（３）２部、メチルトリメトキシシラン２部、テトラメトキシシラン０．５部、コロイダルシリカ０．３部を、イソプロピルアルコール５部、テトラヒドロフラン３部、蒸留水０．３部に溶解させ、イオン交換樹脂（アンバーリスト１５Ｅ）０．５部を加え、室温で攪拌することにより２４時間加水分解を行った。
【０１７３】
【化１２】

【０１７４】
【表１】

【０１７５】
加水分解したものからイオン交換樹脂を濾過分離した液体２部に対し、アルミニウムトリスアセチルアセトナートを０．０４部、３，５−ジ−ｔ−ブチル−４−ヒドロキシトルエン（ＢＨＴ）０．１部を加え、表面保護層塗布液を調製した。この塗布液を前記電荷輸送層の上にリング型浸漬塗布法により塗布した。室温で３０分風乾した後、１７０℃で１時間加熱処理して硬化し、膜厚約３μｍの表面保護層を形成することにより、感光体Ａを作製した。
【０１７６】
＜トナーの作製＞
（トナー粒子１の作製）
・スチレン−ｎブチルアクリレート共重合樹脂（共重合比：７０／３０、Ｔｇ：５８℃、Ｍｎ：４，０００、Ｍｗ：２５，０００） １００部
・カーボンブラック（モーガルＬ：キャボット製） ３部
【０１７７】
上記各成分の混合物をエクストルーダーで混練し、ジェットミルで粉砕した後、風力式分級機で分散して、体積平均粒径Ｄ５０が７．８μｍ、形状係数ＳＦ１が１４８．８のトナー粒子１（黒）を得た。
【０１７８】
（トナー粒子２の作製）
・線状ポリエステル（テレフタル酸／ビスフェノールＡ・エチレンオキシド付加物／シクロヘキサンジメタノールから選られた線状ポリエステル、Ｔｇ：６２℃、Ｍｎ：４，０００、Ｍｗ：３５，０００、酸価：１２、水酸価：２５）８６部・カーボンブラック（Ｒ３３０：キャボット社製） ８部
・ポリエチレンワックス（融点：１３５℃） ６部
【０１７９】
上記各成分の混合物をエクストルーダーで混練し、表面粉砕方式の粉砕機で粉砕した後、風力式分級機で細粒、粗粒を分級し、その中間サイズの粒子を得る過程を３回繰り返し、体積平均粒径Ｄ５０が８μｍ、形状係数ＳＦ１が１２８．５のトナー粒子２（黒）を得た。
【０１８０】
＜キャリアの作製＞
（キャリアＡの作製）
・フェライト粒子（体積平均粒径：５０μｍ） １００部
・トルエン １４部
・スチレン−メタクリレート共重合体（成分比：９０／１０、重量平均分子量：７万） ２部
・カーボンブラック（Ｒ３３０：キャボット社製） ０．２部
【０１８１】
まず、フェライト粒子を除く上記各成分を１０分間スターラーで撹拌させて、分散した被覆樹脂液を調製し、次に、この被覆樹脂液と前記フェライト粒子とを真空脱気型ニーダーに入れて、６０℃において３０分撹拌した後、さらに加温しながら減圧して脱気し、乾燥させることによりキャリアＡを得た。
このキャリアは、１０００Ｖ／ｃｍの印加電界時の体積固有抵抗値が５．０×１０^１１Ωｃｍであった。
【０１８２】
（キャリアＢの作製）
・フェライト粒子（体積平均粒径：５０μｍ） １００部
・トルエン １４部
・スチレン−メタクリレート共重合体（成分比：９０／１０、重量平均分子量：７万） ２部
・カーボンブラック（ＶＸＣ７２：キャボット社製） ０．２部
・架橋メラミン樹脂 ０．２部
【０１８３】
まず、フェライト粒子を除く上記各成分を１０分間スターラーで撹拌させて、分散した被覆樹脂液を調製し、次に、この被覆樹脂液と前記フェライト粒子とを真空脱気型ニーダーに入れて、６０℃において３０分撹拌した後、さらに加温しながら減圧して脱気し、乾燥させることによりキャリアＢを得た。
このキャリアは、１０００Ｖ／ｃｍの印加電界時の体積固有抵抗値が７．０×１０^１１Ωｃｍであった。
【０１８４】
（キャリアＣの作製）
・フェライト粒子（体積抵抗値：１０^８Ω・ｃｍ、体積平均粒径：５０μｍ） １００部
・トルエン １４部
・パーフルオロオクチルエチルアクリレート／メチルメタクリレート共重合体（共重合比４０：６０、Ｍｗ：５万） １．６部
・カーボンブラック（ＶＸＣ−７２：キャボット社製） ０．１２部
・架橋メラミン樹脂（数平均粒子径：０．３μｍ） ０．２部
【０１８５】
上記各成分のうち、フェライト粒子を除く成分を１０分間スターラーで分散し、被覆樹脂層形成用液を調製し、この被覆樹脂層形成用液とフェライト粒子とを真空脱気型ニーダーに入れ、６０℃で３０分間攪拌した後、減圧してトルエンを留去して、フェライト粒子表面に被覆樹脂層を形成して、キャリアＡを製造した。
【０１８６】
樹脂被覆層におけるマトリックス樹脂として用いたパーフルオロオクチルエチルアクリレート／メチルメタクリレート共重合体には、カーボンブラックの粒子および架橋メラミン樹脂の粒子をトルエンにて希釈してサンドミルで分散しておいたため、得られたキャリアにおける樹脂被膜には、カーボンブラックおよび架橋メラミン樹脂の各粒子が均一に分散されていた。
このキャリアは、１０００Ｖ／ｃｍの印加電界時の体積固有抵抗値が２×１０^１２Ωｃｍであった。
【０１８７】
（キャリアＤ及びＥの作製）
前記トナー粒子１の６部と、前記キャリアＣの９４部とを混合し、現像剤Ａを作製した。得られた現像剤Ｃを用いて、電子写真複写機（富士ゼロックス（株）製、Ｃｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機）にてコピーテストを行った。コピー枚数を５万枚、１０万枚の２水準取り、劣化した現像剤Ｄ（５万枚）、現像剤Ｅ（１０万枚）を取り出した。その後、トナーとキャリアとをブローオフ法により分離した。現像剤Ｂから分離したキャリアをキャリアＤ、現像剤Ｅから分離したキャリアをキャリアＥとした。
キャリアＤ、Ｅは、１０００Ｖ／ｃｍの印加電界時の体積固有抵抗値が各々８×１０^１１Ωｃｍ、５×１０^１０Ωｃｍであった。
【０１８８】
（キャリアＦの作製）
キャリアＤをサンプルミルで表面を強制的に粗し（強制劣化）、キャリアの芯材構成成分の表面露出量が３７．１ａｔｏｍ％のキャリアＦを製造した。
このキャリアは、１０００Ｖ／ｃｍの印加電界時の体積固有抵抗値が３×１０^９Ωｃｍであった。
【０１８９】
（キャリアＧの作製）
キャリアＤをサンプルミルで表面を強制的に粗し（強制劣化）、樹脂被覆率（Ｃ／Ｃ_０）が新キャリアであるキャリアＤに対して０．４６であるキャリアＧを作製した。
【０１９０】
上記キャリアＣ〜Ｇの再生条件、および物性の一覧を、表２に明記する。
なお、表１において、芯材構成成分の表面露出量、樹脂被覆率、および芯材の体積電気抵抗は、それぞれ既述の測定手順の例として挙げた手順により測定した。また、樹脂被覆率（Ｃ／Ｃ_０）の計算の基準となる新しい（未使用の）キャリアの樹脂被覆量Ｃ_０は、コピーテスト前あるいは強制劣化前のキャリアについて測定した値である（キャリアＣは、コピーテストも強制劣化も行っていないため、樹脂被覆率は未使用のままであり、Ｃ＝Ｃ_０すなわちＣ／Ｃ_０が１である）。
【０１９１】
【表２】

【０１９２】
＜現像剤の作製＞
前記トナー粒子１、２のそれぞれ１００部に、平均粒子径１５ｎｍのデシルシラン処理の疎水性チタニア０．８部、平均粒子径３０ｎｍの疎水性シリカ（ＮＹ５０、日本アエロジル社製）１．３部を加え、ヘンシェルミキサーを用い周速３２ｍ／秒で１０分間ブレンドを行った後、４５μｍ網目のシーブを用いて粗大粒子を除去し、トナー１及び２を得た。
【０１９３】
前記各種キャリヤ１００部と上記各トナー６部とを、Ｖ−ブレンダーを用い４０ｒｐｍで２０分間攪拌し、１７７μｍの網目を有するシーブで篩うことにより、各種の現像剤を得た。
【０１９４】
＜補給用現像剤の作製＞
前記各トナー１００部に対し、前記各種キャリア１０部の割合で混合させた。これを補給用現像剤とした。
【０１９５】
＜実施例１＞
前記トナー１及びキャリアＡとからなる現像剤１と、前記トナー１及びキャリアＢとからなる補給用現像剤１とを用意した。
リサイクルトナーがトナー補給部に戻るようにしたＦｕｊｉ Ｘｅｒｏｘ社製Ｃｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機のオリジナル感光体（有機感光体）を、表面層がシロキサン結合を有する架橋樹脂からなる感光体Ａに取り替え、補給用現像剤カートリッジに前記補給用現像剤１を、現像器に前記現像剤１を収容して、長期使用テストを実施し、カブリ、画像流れ等を評価した。
【０１９６】
なお、前記Ｃｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機は、静電潜像担持体と、該静電潜像担持体表面を帯電する帯電手段と、帯電された前記静電潜像担持体表面に静電潜像を形成する静電潜像形成手段と、トナー及びキャリアからなる現像剤が内部に収容され、現像剤担持体表面に形成された前記現像剤の層により前記静電潜像を現像し、前記静電潜像担持体表面にトナー画像を形成する現像器と、前記トナー画像を中間転写体に転写する転写手段と、クリーニングブレード方式によるクリーニング手段とを含む画像形成装置であり、トリクル現像方式を採用している。
また、プロセススピードは、２６０ｍｍ／ｓｅｃとした。
【０１９７】
この際、一定枚数プリント毎に静電潜像担持体表面にトナーバンドを形成し、そのトナーバンドは転写されずに全量がクリーニング装置で回収されるように制御した。このトナーバンド形成頻度を変化させて、トナーカートリッジから供給される補給トナー全量中のリサイクルトナーの割合が、初期からＡ４サイズの画像を５０００枚プリントした時に１５質量％となるように調整した。
【０１９８】
なお、上記補給トナー全量中のリサイクルトナーの割合は、一定枚数プリントごとに、トナー補給部に回収されるリサイクルトナー量と、補給用現像剤カートリッジから現像剤中に補給される補給用現像剤量とを、前記評価機を１分間駆動させた状態で各々測定することにより求めた。
【０１９９】
５０００枚以降、上記条件を維持しつつ１０００００枚までプリントを行い、その時点でのトナー帯電量、画質（紙上カブリ、画像流れ）を評価した。なお、紙上カブリ、画像流れは下記の基準により評価した。
【０２００】
−紙上カブリ−
プリント画像の非画像部のカブリを目視で官能評価し、以下のように判断した。
・○ ・・・ 全く汚れていない。
・△ ・・・ やや汚れを感じるが、許容レベル。
・× ・・・ 非現像領域（余白部）と非画像部との境界がわかるほど汚れている。
【０２０１】
−画像流れ−
プリント画像の非画像部のカブリを目視で官能評価し、以下のように判断した。
・○ ・・・ 流れが全くない。
・× ・・・ 流れが見られる。
結果を表３に示す。
【０２０２】
＜実施例２＞
実施例１において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、２０質量％となるように調製した以外は実施例１と同様にして評価を行った。結果を表３に示す。
【０２０３】
＜実施例３＞
実施例１において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、２５質量％となるように調製した以外は実施例１と同様にして評価を行った。結果を表３に示す。
【０２０４】
＜比較例１＞
実施例１において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、１０質量％となるように調製した以外は実施例１と同様にして評価を行った。結果を表３に示す。
【０２０５】
＜比較例２〜５＞
実施例１〜３、比較例１において、評価機であるＣｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機のトリクル現像方式をやめ、トナー補給方式（補給用トナーは各々の現像剤に使用したトナー）とした以外は同様にして評価を行った。結果を表３に示す。
【０２０６】
【表３】

【０２０７】
＜実施例４＞
前記トナー２とキャリアＡとからなる現像剤２と、前記トナー２とキャリアＢとからなる補給用現像剤２を用意した。
実施例１において、現像剤１及び補給用現像剤１の代わりに上記現像剤２及び補給用現像剤２を用いた以外は実施例１と同様にして評価を行った。結果を表４に示す。
【０２０８】
＜実施例５＞
実施例４において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、２０質量％となるように調製した以外は実施例４と同様にして評価を行った。結果を表４に示す。
【０２０９】
＜実施例６＞
実施例４において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、２５質量％となるように調製した以外は実施例４と同様にして評価を行った。結果を表４に示す。
【０２１０】
＜比較例６＞
実施例４において、５０００枚プリント後の補給トナー中のリサイクルトナーの割合が、１０質量％となるように調製した以外は実施例４と同様にして評価を行った。結果を表４に示す。
【０２１１】
＜比較例７〜１０＞
実施例４〜６、比較例６において、評価機であるＣｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機のトリクル現像方式をやめ、トナー補給方式（補給用トナーは各々の現像剤に使用したトナー）とした以外は同様にして評価を行った。結果を表４に示す。
【０２１２】
【表４】

【０２１３】
表３及び４に示すように、本発明の画像形成方法である、補給トナー全量中のリサイクルトナーの割合を１５質量％以上とした場合には、紙上カブリ、プリント画像の画像流れもなく良好だった。一方、補給トナー中のリサイクルトナーの割合が１０質量％の場合は、紙上カブリ、プリント画像の画像流れがあり、不十分な画質であった。
また、トリクル現像方式を採用することにより、長期にわたり紙上カブリ、プリント画像の画像流れもない良好な画質が得られた。
【０２１４】
＜実施例７〜１２＞
前記トナー粒子１と、前記キャリアＣ〜Ｇとを各々順次組み合わせて混合し、現像剤３〜７及び補給用現像剤３〜７を用意した。
前述の実施例１で用いた感光体Ａを装着した電子写真複写機（Ｃｏｌｏｒ ＤｏｃｕＴｅｃｈ６０改造機）にて、これらの現像剤及び補給用現像剤を表５に示すように組み合わせて用いて、リサイクルトナーの割合をいずれの試験においても１５質量％となるように調整し、コピーテストを行った。結果を下記表５に示す。
【０２１５】
なお、表５におけるコピーテストの画質評価は、まず、テスト開始時については、濃度階調のあるチャートのコピーを行い、その階調性、濃度の均一性、エッジ効果の有無を目視で評価した。１０万枚複写後の画質については、粒状性、階調性／擬似輪郭、濃度再現性、その他の画質欠陥の観点から目視で評価した。
【０２１６】
【表５】

【０２１７】
【発明の効果】
本発明によれば、いわゆるトリクル現像方式を採用した現像手段を有し、クリーニング手段により静電潜像担持体表面から回収された残留トナーを、トナー回収装置を介して現像部またはトナー補給部の中に戻して、リサイクルトナーとして再使用する画像形成方法において、高速プロセスにおいても画像ディフェクトなく安定に高品位な画像を提供し続ける画像形成方法を提供することができる。また本発明によれば、クリーニング手段によるクリーニング特性を安定させ、静電潜像担持体としての特性を長期に維持できる画像形成方法を提供することができる。
【図面の簡単な説明】
【図１】体積固有抵抗値を測定する方法を説明するための概略図である。
【符号の説明】
１ ガード電極
２ 上部電極
３ 測定試料
４ 下部電極
５ 試料保持リング
６ エレクトロメータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method in which an electrostatic latent image is developed to form an image by a method such as electrophotography or electrostatic recording.
[0002]
[Prior art]
In electrophotography, an electrostatic latent image formed on the surface of a photoreceptor (electrostatic latent image carrier) is developed with a toner containing a colorant, and the resulting toner image is transferred to the surface of a transfer target. An image is obtained by fixing with a heat roll or the like. On the other hand, the electrostatic latent image carrier is cleaned to form an electrostatic latent image again. A dry developer (developer) used in such electrophotography is a two-component developer in which a toner in which a colorant is blended with a binder resin is used alone and a carrier mixed with the toner. Broadly divided into developers.
[0003]
In a general electrophotographic apparatus using such an electrophotographic method, as described above, the electrostatic latent image on the electrostatic latent image carrier is developed with toner, and the toner image is transferred to an intermediate transfer member or the like. The toner that is transferred to the body but remains on the surface of the electrostatic latent image carrier without being transferred after the toner image is transferred is cleaned by a cleaning device, collected in a collection container, and discarded. Therefore, if the recycled toner that reuses the residual toner can be used effectively, resources can be used effectively.
[0004]
However, when the recycled toner is used, paper dust of transfer paper (recording medium) is mixed in the developer, or toner in which the external additive is buried or peeled off. The problem is that problems such as scattering are likely to occur. Further, since the charge amount of such a toner is reduced, there is a concern about mixing with these developers with respect to charge maintenance. Therefore, the amount of recycled toner used can be restricted from the viewpoint of charge maintenance.
[0005]
Regarding the use of recycled toner, in order to improve durability, the release agent amount and external additive amount are specified to suppress the deterioration of the carrier, or the initial toner external additive amount is the amount of external additive of the replenishing toner. There has been proposed a method for improving fluidity and charging stability with a combination of toners to be reduced (see, for example, Patent Documents 1 and 2). Further, in a toner to which two kinds of fine particles having different spheroidization degrees are added, the transfer efficiency is a combination in which the charge amount of the toner is between the charge amount of the toner base particles to which no fine particles are added and the charge amount of the fine particles alone. The amount of waste toner can be reduced (see, for example, Patent Document 3).
However, any of the above methods is not sufficient as a means for stably obtaining a high-quality image using recycled toner.
[0006]
On the other hand, in an image forming apparatus such as a copying machine or a printer, a developing device using a two-component developer composed of toner and a carrier does not consume the carrier in the developing device. As the usage time increases, the charging performance of the carrier decreases due to peeling of the resin coating layer on the surface of the carrier due to stirring, toner adhesion to the surface, and the like.
[0007]
Therefore, as the carrier, from the viewpoint of high durability, various resin coatings that do not change the chargeability of the toner, are excellent in impact resistance and friction resistance, and are stable with respect to environmental changes such as humidity and temperature. A career has been proposed.
For example, coating the surface of the carrier core with a copolymer of a nitrogen-containing fluorinated alkyl (meth) acrylate and a vinyl monomer, or a copolymer of a fluorinated alkyl (meth) acrylate and a nitrogen-containing vinyl monomer. Has proposed a method for obtaining a relatively long-life coated carrier (see, for example, Patent Documents 4 to 6).
[0008]
However, in the case of these carriers, there is a problem that contamination (impact) of the carrier surface by the toner component cannot be prevented. In order to prevent the impact of the toner component on the carrier surface, it is also considered to form a carrier film using a resin having a small surface energy such as a silicone resin or a fluorine resin. . However, in such a resin-coated carrier, the silicone resin and the fluorine-based resin are present in a relatively large amount near the surface of the carrier coating layer, but there are only a few in the thickness direction of the coating layer. In the case of a carrier, there is a problem that when the carrier is used for a long period of time, the effect of the resin is gradually lost due to wear of the film, and the impact is gradually generated. In addition, when continuous copying is performed using a developer containing such a carrier, an image with excellent density reproducibility and image quality can be obtained initially, but the image density decreases after copying tens of thousands of sheets. However, gradation and graininess become poor. In other words, image quality deterioration due to contamination (impact) on the carrier surface has been unavoidable.
Therefore, in order to prevent the copy image quality from being deteriorated due to the deterioration of the carrier, conventionally, the developer is mainly changed periodically to prevent the image quality from being lowered.
[0009]
However, the developer that has been exchanged and has been contaminated (impacted) on the carrier surface, which has been collected and discarded in the past, has recently become a problem as an environmental destruction caused by industrial waste, and the regeneration of the developer is one of the problems. It has become. Regarding the regeneration of the developer, for example, a method of regenerating the recovered developer by heating at a high temperature (about 1000 ° F.) has been proposed (see, for example, Patent Document 7). In this method, the ferrite carrier is regenerated. , Has the disadvantage of not returning to the original characteristics. Further, a method of removing carrier contamination by combining with a thermally decomposable toner without damaging the coating layer on the carrier surface has been proposed (see, for example, Patent Document 8). However, there is a problem that the developer characteristics are limited.
[0010]
2. Description of the Related Art In recent years, in color image forming apparatuses that are in high demand, a method of superimposing a plurality of color toners stored in a plurality of developing devices on a recording medium is common. For this reason, there are various methods such as a retraction method and a tandem method in addition to a so-called rotary method in which a rotating body equipped with a plurality of developing devices is rotated and a developing device of a plurality of colors is sequentially opposed to or contacted with a photosensitive member. It is used.
[0011]
However, in these color image forming apparatuses, the size per developing unit is limited due to limitations on the space around the electrostatic latent image carrier or the size of the apparatus, and there is sufficient developer in each developing unit. The amount cannot be secured. As a result, the developer replacement interval is shortened, increasing the service cost for developer replacement, and increasing the unit price per image due to frequent replacement of developer cartridges. It was.
[0012]
As a technique for solving the above problems, a trickle developing technique is conventionally known.
In the trickle development method, the developer is gradually replenished inside the developing device in order to prevent the developer charging performance from deteriorating and extend the developer replacement interval. This is a development system in which development is performed while recovering a deteriorated developer from the inside of the developing device. In this trickle developing method, the deteriorated developer in the developing device is gradually replaced with a new developer, the charging performance of the developer in the developing device can be maintained constant, and the deterioration of copy image quality can be suppressed.
[0013]
In this trickle development method, it is necessary to replenish and collect the developer so that the amount of developer in the developing device is always maintained at a specified value. As the trickle development technology, a trickle development method has been proposed in which a developer is gradually replenished in order to extend the developer replacement interval while an excess deteriorated developer is overflowed and collected. (For example, refer to Patent Document 9).
[0014]
However, when this trickle development method is adopted, the durability of the developer itself is improved, but in this method, a large amount of developer (carrier and toner) is consumed due to the mechanism (a mechanism for gradually replenishing the developer). Must. Therefore, the present situation is that a sufficient effect cannot be obtained in terms of cost reduction as described above.
[0015]
On the other hand, in order to maintain the characteristics of the photoreceptor as an electrostatic latent image carrier for a long period of time, it is necessary to control the system so that the surface of the photoreceptor is worn to some extent. If the wear is too small, the surface of the photoreceptor is contaminated, and defects such as “white spots” in which the image density decreases as a copy or print image, or “image flow” in which the character image is blurred are likely to occur. Furthermore, this wear must proceed as uniformly as possible over the entire photoreceptor surface.
[0016]
Various methods such as a method using a fur brush or a magnetic brush or a method using a cleaning blade whose material is an elastic material are used as cleaning means for removing residual toner on the photosensitive member. A means for rubbing the electrostatic latent image bearing member using a cleaning blade, which is an elastic body, and scraping off the toner (hereinafter sometimes referred to as “blade cleaning means”) is inexpensive and has stable performance. Is more commonly used than high. However, the blade cleaning means may cause various problems such as wear and scratches on the electrostatic latent image carrier and must be precisely controlled.
[0017]
In order to stably control blade cleaning, titanium oxide particles treated with fatty acid metal salt, titanium oxide fine particles surface-treated while hydrolyzing fatty acid compound in aqueous system, inorganic compound surface treated with fatty acid metal salt, fatty acid A method of adding fine particle titanium oxide or the like hydrophobized by surface treatment with aluminum to toner particles has been proposed (see, for example, Patent Documents 10 to 13). In these methods, by using a fatty acid metal salt for the surface treatment, the above-mentioned problem derived from the size of the particle size of the fatty acid metal salt itself is avoided to some extent. However, in either case, the effect on the surface of the photoreceptor is insufficient, although some effects are exhibited.
[0018]
On the other hand, hydrophobic hard fine powder is externally added to the toner, and the photoconductor is scraped by the polishing effect of the hard fine powder to prevent toner filming (see, for example, Patent Document 14). However, although this method is effective for suppressing filming, there is a drawback that the surface of the photoreceptor is worn and the life of the photoreceptor is remarkably reduced. At the same time, there is a drawback that the cleaning blade is worn by the hard fine powder and the blade life is remarkably reduced.
[0019]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-209902
[Patent Document 2]
JP-A-11-95553
[Patent Document 3]
Japanese Patent Laid-Open No. 11-153881
[Patent Document 4]
JP 61-80161 A
[Patent Document 5]
JP 61-80162 A
[Patent Document 6]
JP 61-80163 A
[Patent Document 7]
JP-A-47-12286
[Patent Document 8]
Japanese Patent Laid-Open No. 6-149132
[Patent Document 9]
Japanese Patent Publication No. 2-21591
[Patent Document 10]
JP-A-4-452
[Patent Document 11]
JP-A-5-66607
[Patent Document 12]
JP-A-5-165250
[Patent Document 13]
JP-A-10-161342
[Patent Document 14]
JP-A-2-89064
[0020]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, the present invention has a developing unit employing a so-called trickle developing system, and the residual toner recovered from the surface of the electrostatic latent image carrier by the cleaning unit is transferred to the developing unit or the toner replenishing unit via the toner recovery unit. An object of the present invention is to provide an image forming method for returning to the inside and reusing the recycled toner as a recycle toner, and continuously providing a high-quality image without image defects even in a high-speed process.
Another object of the present invention is to provide an image forming method capable of stabilizing the cleaning characteristics of the cleaning means and maintaining the characteristics as an electrostatic latent image carrier for a long period of time.
[0021]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have determined that the above object can be achieved by setting a specific toner recycling ratio (the ratio of the recycled toner in the total amount of replenished toner). The headline and the present invention were completed.
[0022]
That is, the present invention
<1> At least charging means for charging the surface of the electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrostatic latent image carrier, and the electrostatic latent image Developing means for developing an image as a toner image using a developer; transfer means for transferring the toner image to a transfer target; cleaning means for removing toner remaining on the surface of the electrostatic latent image carrier after transfer; and transfer An image forming method for forming an image with an image forming apparatus having a fixing unit for fixing the toner image to a recording medium,
The developing means appropriately replenishes a developer for replenishment containing toner and carrier into the developer containing a developer composed of toner and carrier, and removes the excess developer from the developer. A developer recovery mechanism for recovering from the inside; the toner recovered from the electrostatic latent image carrier by the cleaning means is reused as recycled toner; The image forming method is characterized in that the ratio of the recycled toner is 15% by mass or more.
[0023]
<2> The developer recovered from the inside of the developing device is separated into a carrier and a toner, and the separated carrier is reused as a recycling carrier for the initial developer or the replenishment developer, and The image forming method according to <1>, wherein the surface exposure amount of the core component of the carrier is in the range of 0 to 30 atom%.
[0024]
In the present invention, it is preferable that the surface layer of the latent electrostatic image bearing member includes a crosslinked resin having charge transporting properties and having a siloxane bond. Further, it is preferable that the shape factor SF1 of the toner is in the range of 100 to 140.
[0025]
Further, the present invention preferably includes a toner band forming step of forming a toner band to be supplied to the cleaning unit on the surface of the electrostatic latent image carrier during non-image formation in development. The proportion is preferably 20% by mass or more.
[0026]
In the present invention, a developer composed of a carrier and a toner is used, and the carrier preferably has a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on the surface of the core material. The toner preferably contains a release agent.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The present invention relates to an image forming method for forming an image by a developing means adopting a so-called trickle developing method and an image forming apparatus adopting a toner recycling mechanism. The ratio is 15% by mass or more.
[0028]
As described above, in the image forming method using the recycled toner, since the external additive is buried or peeled off compared to the unused toner, the image quality deteriorates due to the mixing in the developer. Problems such as toner scattering. This is because the toner charge amount becomes unstable because the external additive added to the toner base particles is detached by stress such as cleaning or embedded in the toner base particles. Therefore, in order to improve various properties of the recycled toner, it is important that there is no change or small change in the toner structure between the unused toner and the recycled toner.
[0029]
By the way, the conventional viewpoint for improving the above problem is to make the toner itself a structure in which the toner structure does not easily change, or to prevent the charging characteristics from changing even if the toner structure changes.
[0030]
As a result of intensive studies by the present inventors, when a large amount of toner is collected in the cleaning part (sliding part between the photoreceptor and the cleaning member) in the cleaning process, the collected toner can be used favorably as a recycled toner. I found. This is because the stress applied to the toner in the cleaning unit is dispersed due to the large amount of toner present therein, the stress applied to each toner is minute, and further, the change in the toner structure is suppressed to a small extent. This is thought to be the cause.
[0031]
Therefore, even in a trickle development type development system used to extend the life of the developer by increasing the amount of toner supplied to the cleaning unit and reducing the structural change of the recycled toner, image quality degradation, toner scattering, etc. It is possible to maintain a higher quality image without image defects. The inventors have found that the above effect is particularly remarkable in an image forming apparatus that employs a high-speed process in which recycled toner is more susceptible to greater stress.
[0032]
In addition, since the toner is abundant in the cleaning unit, the cleaning characteristics can be stabilized. In blade cleaning, as described above, the electrostatic latent image carrier is rubbed with the cleaning blade to scrape the residual toner, so the edge of the cleaning blade is caused by the frictional resistance between the electrostatic latent image carrier and the cleaning blade. Is deformed to form a minute wedge-shaped space (microtack under part). The toner that has entered the micro-tack under part is difficult to replace and forms a non-flow region. In fact, the presence of this non-flow region is important for blade cleaning, and the non-flow region functions to actually scrape off the toner.
[0033]
Therefore, since the toner is abundant in the cleaning portion, the non-flow region is uniformly formed in the entire micro tack-under portion. As a result, the cleaning characteristics are stabilized, and it is possible to prevent image defects such as “white spots” in which the image density is lowered as a print image and “image flow” in which the character image is blurred.
[0034]
As described above, in the present invention, by supplying abundant toner to the cleaning unit, it is possible to reduce the stress on the toner during cleaning and at the same time to stabilize the cleaning characteristics. Since the recycled toner is stored in a developing unit or the like together with the replenishment developer when the image forming apparatus is used, the toner supply amount of the replenishment toner is the total amount of replenishment toner combined with the toner in the replenishment developer and the recycle toner. The percentage of recycled toner.
[0035]
In the present invention, the ratio of the recycled toner in the total amount of the replenished toner needs to be 15% by mass or more. When the ratio of the recycled toner is less than 15% by mass, the amount of toner supplied to the cleaning unit is not sufficient, the toner structural change cannot be made minute, and the non-flow region in the microtack under part is uniform. Can not be formed.
[0036]
Furthermore, the ratio of the recycled toner in the total amount of the replenished toner is preferably 20% by mass or more, and more preferably 25% by mass or more. However, if the ratio of the recycled toner in the replenished toner becomes too high, the toner concentration in the developer after replenishment becomes too high, and efficient frictional charging with the carrier may not be performed. The upper limit is about 50% by mass.
[0037]
In an image forming apparatus having a toner recycling mechanism, there is no or little recycled toner at the time of initial image formation. Therefore, the ratio of the recycled toner in the total amount of the replenished toner is 15 masses as defined in the present invention. “% Or more” means a condition to be satisfied after 5000 sheets are printed on an A4 size recording sheet (recording medium) after starting to use a new image forming apparatus that does not perform image formation at all.
[0038]
Hereinafter, the present invention will be described in more detail.
In order to make the ratio of the recycled toner in the total amount of the replenished toner 15% by mass or more, it is necessary to supply abundant toner to the cleaning unit. However, when the toner is recycled by forming an image with normal transfer efficiency In this case, since the ratio of the recycled toner is in the range of about 5 to 12% by mass, the target ratio of the recycled toner cannot be obtained.
[0039]
A method for achieving this is not particularly limited. For example, a method of supplying a large amount of toner to the cleaning unit by reducing the toner transfer efficiency to increase the residual toner on the surface of the photoreceptor, so-called a toner band is systematically used. A method of providing and supplying abundant toner to the cleaning unit can be considered.
Hereinafter, a toner band forming method that is preferably used in the present invention in order to achieve the required ratio of recycled toner will be described.
[0040]
In general, in electrophotographic image formation, depending on the image to be produced, the amount of toner supplied to the cleaning unit is extremely small in areas where there are few images, such as non-image areas. By supplying toner to the lacking portion (toner band forming step), it becomes possible to compensate for the shortage of toner in the cleaning unit.
[0041]
That is, a predetermined amount of toner is supplied to supply a cleaning amount corresponding to a portion having no image or a portion having a small amount without supplying excessive toner to a cleaning portion corresponding to a portion having a large image on the surface of the photoreceptor. A toner band is formed. The “non-image forming time” refers to a time when a normal image forming cycle is not performed, such as during the time when the recording paper is not supplied between the image forming cycle and the next image forming cycle.
[0042]
The toner image formed as the toner band may be a pattern in which toner is supplied to the entire longitudinal direction of the cleaning blade, and may be a solid image, a halftone image, a line image, or the like. ) Direction length is in the range of 0.5 mm to 20 mm, the length orthogonal to the photoconductor rotation (movement) direction is equal to the length in the longitudinal direction of the cleaning blade, and the image density is in the range of 30 to 100%. More preferably.
[0043]
If the length in the rotational direction is less than 0.5 mm, the toner may not be stably supplied to the cleaning blade regardless of the image density, and the surface of the photoreceptor may not be uniformly polished. If the length in the rotational direction exceeds 20 mm, the toner may be excessively supplied to the elastic cleaning blade.
On the other hand, if the image density is less than 30%, the toner may not be stably supplied to the elastic cleaning blade regardless of the image density, and the surface of the photoreceptor may not be uniformly polished.
[0044]
The timing for forming the toner band may be any fixed timing, cycle, time, etc., and may be any timing. However, the interval is an A4 size image from 1 to 200 prints per 10 prints. It is preferable that the range be one time. If the interval is more than once for printing 200 sheets of A4 images, the ratio of the recycled toner in the replenished toner may not be stably 15% by mass or more.
[0045]
By forming the toner band in this way during non-image formation, the entire area where the cleaning blade comes into contact with the photoconductor is more independent of the density of the image to be produced and the variation in its temporal frequency. Abundant toner can be stably supplied to the rubbing portion between the cleaning blade and the photosensitive member.
[0046]
The toner band can be supplied for any number of photoconductors, in the case of a copying machine, the integrated image reading information by a CCD sensor or the like, in the case of a printer, the integrated pixel information of the axial position of the photoconductor of the output image information. Simply storing “integrated image information”), and based on this information, a toner image corresponding to the accumulated image information at each axial position is produced in a non-image forming cycle and supplied to the cleaning blade. Can be achieved.
[0047]
In the present invention, as described above, the formation timing of the toner band on the surface of the photoreceptor is controlled, and the formed toner band is removed by an elastic cleaning blade or the like using an elastic body as a material. The ratio of the recycled toner in the toner can be a certain value or more. As a result, the stress applied to the toner can be reduced, the change in the toner structure can be reduced, the image density is reduced due to the contamination of the photoconductor, “white spots”, the character image is blurred, “image flow”, etc. Defects, wear and scratches can be suppressed, and good cleaning properties can be secured.
[0048]
<Developer>
As the developer used in the present invention, a two-component developer composed of a toner and a carrier is used from the viewpoint of full-color image formation and ease of toner charge amount control, and a developer containing the developer. Is supplied with a replenishment developer containing toner and carrier (trickle development system).
[0049]
(toner)
The toner used for the developer in the present invention is preferably composed of a binder resin, a colorant, and a release agent added as necessary, and having a volume average particle diameter in the range of 2 to 8 μm. . In addition to obtaining high developability, transferability, and high-quality images, the toner fluidity is improved, and after being collected by the cleaning unit, the collected toner (recycled toner) is collected in the developing unit, toner replenishing unit, etc. ), The toner shape factor SF1 is preferably in the range of 100 to 140, more preferably in the range of 110 to 135.
[0050]
The shape factor SF1 means an average value of values calculated by the following formula for individual toner particles, and SF1 is 100 in the case of a true sphere.
SF1 = (ML ² / A) × (π / 4) × 100
In the above equation, ML represents the maximum toner length, and A represents the projected area of the toner.
[0051]
As described above, in the present invention, the amount of toner supplied to the cleaning unit is increased, and the stress applied to the toner is reduced, thereby reducing the change in the toner structure of the recycled toner. Therefore, it is preferable that the toner physical properties such as the shape and particle diameter of the recycled toner are almost the same as the specified range.
[0052]
The method for producing the toner used in the present invention is not particularly limited by the production method as long as it satisfies the above shape factor and particle size, and a known method can be used.
For the production of the toner, for example, a binder resin, a colorant, a release agent, and, if necessary, a kneading and pulverizing method in which a charge control agent and the like are kneaded and pulverized and classified. A method of changing the shape by mechanical impact force or thermal energy, emulsion polymerization of a polymerizable monomer to obtain a binder resin, a formed resin dispersion, a colorant, a release agent, as required In accordance with this, an emulsion polymerization aggregation method for obtaining toner particles by mixing with a dispersion such as a charge control agent, and aggregating and heating and fusing, a polymerizable monomer and a colorant for obtaining a binder resin, and a release agent In addition, a suspension polymerization method in which a solution such as a charge control agent is suspended in an aqueous solvent for polymerization, if necessary, a binder resin, a colorant, a release agent, and a charge control agent as necessary. A solution suspension method in which a solution is suspended in an aqueous solvent and granulated can be used. In addition, a manufacturing method may be performed in which the toner particles obtained by the above method are used as a core, and fine particles are further adhered and heat-fused to have a core-shell structure.
[0053]
In the toner used in the present invention, when the internal additive is added to the inside of the toner particles by, for example, a kneading and pulverizing method, it is carried out by a kneading process. The kneading at this time can be performed using various heating kneaders. As the heat kneader, a three-roll type, a single screw type, a twin screw type, a Banbury mixer type, and the like are known.
[0054]
As described above, the production method of the toner used in the present invention is arbitrary, but in order to control the shape factor in the production process, for example, in the kneading and pulverization method, pulverization such as a collision plate type or a jet type is used. There is a choice of method. A device that causes toner to collide with an object such as a collision plate type is called a surface pulverization type, and examples of the device include a micronizer, ulmax, and a jet-o-mizer. A device that causes toners to collide with each other is called a volume grinding type, and examples of the device include KTM (krypton) and a turbo mill.
[0055]
Further, as a volume / surface grinding mold having a collision plate on the volume grinding mold and having both characteristics, there is an I-type Jet-Mill. In general, the pulverized product tends to be indeterminate in the volume pulverization type, and is more likely to be round in the surface pulverization type. Also, the shape changes depending on the number of classifications, and the more the number of classifications, the more likely it becomes round. Furthermore, the shape can be changed by adding a hybridization system (manufactured by Nara Machinery Co., Ltd.), mechano-fusion system (manufactured by Hosokawa Micron Corporation), kryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), etc. Can also be mentioned.
[0056]
Binder resins used include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Examples of vinyl polymers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene- Mention may be made of maleic anhydride copolymers, polyethylene, polypropylene and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.
[0057]
In the image forming method in which toner is recycled as in the present invention, it is preferable to use a styrene-alkyl acrylate copolymer, polyester, or the like from the viewpoint of fixability among the binder resins.
[0058]
In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 238, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.
[0059]
The toner used in the present invention preferably contains a release agent.
Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.
[0060]
As the release agent contained in the toner used in the present invention, it is preferable to use low molecular weight polyethylene, low molecular weight polypropylene, carnauba wax or the like from the viewpoint of not plasticizing the binder resin.
The content of the release agent is preferably in the range of 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin.
[0061]
In addition, a charge control agent may be added to the toner used in the present invention as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.
[0062]
Furthermore, in order to further improve the long-term storability, fluidity, developability and transferability of the toner, the toner used in the present invention may contain inorganic powder and resin powder on the surface of the toner particles. . Examples of the inorganic powder include carbon black, silica, alumina, titania, zinc oxide, strontium titanate, cerium oxide, and calcium carbonate. Examples of the resin powder include spherical particles such as polystyrene, polymethyl methacrylate (PMMA), nylon, melamine resin, benzoguanamine resin, and fluorine-based resin, and amorphous powders such as vinylidene chloride resin and fatty acid metal salts.
[0063]
Among the inorganic powders and resin powders, silica, titanium compounds, alumina and the like are preferably used in the image forming method for recycling the toner of the present invention from the viewpoint of powder flowability.
[0064]
When the inorganic powder or resin powder is added to the toner surface, the amount added is 0.1 to 4% by mass, more preferably 0.2 to 3% by mass. The Mixing can be performed by a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer.
Moreover, it does not matter even if it goes through a sieving process after external addition mixing.
[0065]
(Career)
On the other hand, as the carrier, a resin-coated carrier having a resin coating layer on the surface of the core material is preferably used. Preferably, conductive particles and the like are dispersed and contained in the resin coating layer. When the spherical toner is used, the packing property is inevitably improved at the conveyance restriction portion in the developing device, and accordingly, a strong force is applied not only to the toner surface but also to the carrier. Therefore, by containing conductive particles dispersed in the resin coating layer of the carrier, even if the resin coating layer is peeled off, the volume specific resistance of the carrier is not greatly changed, and as a result, high image quality can be maintained over a long period of time. This is because it can be made possible.
[0066]
Moreover, in this invention, it is preferable that the surface exposure amount of the core material component of the said carrier is the range of 0-30.0 atom%.
Even if the carrier in which the surface exposure amount of the core component is in the range of 0 to 30.0 atom% is a carrier generally discarded from the trickle developing type image forming apparatus used in the present invention, it is sufficiently used. It has good charging characteristics as much as possible. By using this as a recycle carrier for an electrostatic charge image developer for initial (start) or replenishment (trickle), the carrier can be used effectively. be able to.
[0067]
That is, the electrostatic latent image developer discharged and collected from the trickle developing type image forming apparatus is separated into carrier and toner, and the surface exposure amount of the core component is in the range of 0 to 30.0 atom%. By using the separated carrier, the carrier can be reused without removing / re-coating the resin film by a combustion method or a solvent method.
[0068]
As described above, the “trickle development system” is a system that employs a system that discharges an excess amount while replenishing a replenishment developer composed of toner and a carrier in an electrophotographic image forming apparatus. Refers to that. In the trickle developing system, new carriers are constantly supplied into the developing device at a constant rate by the mechanism. As a result, the carrier deterioration (external additive impact, coating weight loss) is alleviated because there is a certain change compared to the type in which the carrier as in the conventional developing system is used up in the developing device.
[0069]
In the present invention, as described above, the recycle carrier is used for the core component having a surface exposure amount of preferably 0 to 30.0 atom%, more preferably 0 to 10.0 atom%. It is preferable to be used as a reuse.
[0070]
When the surface exposure amount of the core component is 0 atom%, the carrier surface is completely covered with the resin film. If it is completely covered with a resin film, the original function of the resin-coated carrier is exhibited. On the other hand, when the surface exposure amount of the core component exceeds 30.0 atom%, toner or an external additive may selectively adhere to the exposed surface and the charging ability of the carrier may be significantly reduced.
[0071]
In the present invention, the “surface exposed amount of the core component” refers to the area of the resin-coated carrier that is not covered with the resin on the carrier surface, that is, the exposed core material area. As a specific measurement method, It is calculated from the element number ratio measured by XPS (for example, JPS80 (manufactured by JEOL)). That is, it is obtained from the ratio of the number of elements between the resin film component and the core material component by XPS.
[0072]
In the actual measurement, only some main components of the resin coating component and the core component are measured by XPS, the number of elements is counted and totaled, and the total of all obtained main components is calculated. What is necessary is just to calculate from an element number ratio (of course, all elemental analysis may be performed). Here, the main component includes, for example, C, F, N, Si, O and the like as the components of the resin film, and the components of the core material include Fe, Ni, Co, Mn, Cr, O etc. are mentioned. As these main components, a total of 90% or more (more preferably, from among all components constituting the resin coating or the core material (excluding elements contained in both. However, so-called trace elements are not limited to this). The components may be selected (preferably in descending order of the constituent ratio) so that it becomes 95% or more. Below, the example of the specific measurement procedure of the surface exposure amount of the core material component of a carrier is shown.
[0073]
-Examples of procedures for measuring the amount of surface exposure of carrier core components-
(1) A 10 g sample is taken for the developer to be measured.
(2) Place 10 g of the above sample and 1% aqueous surfactant solution in a 50 ml beaker, and separate them by shaking for 5 minutes with an ultrasonic shaker.
{Circle around (3)} After shaking, leave the sample for several minutes, discard the solution while holding the sample in the beaker with a magnet from the outside, and take out only the carrier.
(4) The taken-out carrier is put into a dryer, and moisture is removed by drying.
(5) The dried carrier is set in an aluminum cell of 10 mm × 10 mm of XPS (JPS80 (manufactured by JEOL)) and measured. At this time, as the measurement element, the main component elements of the resin coating component and the core material component are selected.
The element number ratio is calculated from the measurement result, and this is defined as the surface exposure amount.
[0074]
−Core material−
In the carrier of the present invention, the core material has a volume electric resistance of 10 ⁵ -10 ^9.5 It is preferably in the range of Ωcm. ⁷ -10 ⁹ A range of Ωcm is more preferable. Volumetric electrical resistance is 10 ⁵ If it is smaller than Ωcm, when the toner concentration in the developer decreases due to repeated copying, charges may be injected into the carrier and the carrier itself may be developed. On the other hand, the volume electric resistance is 10 ^9.5 It has been confirmed that when it exceeds Ωcm, the image quality may be adversely affected, such as a prominent edge effect or pseudo contour.
[0075]
There is no restriction | limiting in particular as a measuring method of the volume electrical resistance of the said core material of a carrier, What is necessary is just to measure by a conventionally well-known method. As a measuring device, for example, SM8210 type super megaohm meter (manufactured by Toa Denpa Kogyo Co., Ltd.) can be used.
[0076]
Examples of the core material of the carrier include magnetic metals such as iron, steel, nickel, and cobalt, alloys of these with manganese, chromium, rare earth, and magnetic oxides such as ferrite and magnetite. From the viewpoint of core resistance, ferrite is preferred, and alloys with manganese, lithium, strontium, magnesium, etc. are particularly preferred.
The volume average particle diameter of the core material is generally in the range of 10 to 500 μm, and preferably in the range of 30 to 100 μm.
[0077]
-Resin coating-
When the carrier in the present invention is reused as a recycled carrier, the resin coating amount C (mass%) is a new (unused) carrier resin coating amount C. ₀ It is preferable that the following condition is satisfied with respect to (mass%).
0.5 ≦ C / C ₀ ≦ 1.0
The above C / C ₀ This value is referred to as the resin coverage.
[0078]
The lifetime of the developer largely depends on the resin coating amount of the carrier. That is, as the resin coating amount decreases, the charge amount decreases, and as a result, the image quality is adversely affected (white spots, fogging, etc. due to carrier scattering). The carrier in the present invention exhibits performance equivalent to that of a new carrier in the trickle development method, particularly by satisfying the above resin coverage condition.
[0079]
Here, the resin coating amount of the carrier refers to the mass ratio (%) of the resin coating in the entire carrier, and the measurement method is not limited. Below, the example of the specific measurement procedure of the resin coating amount of a carrier is shown.
[0080]
-Example of measurement procedure for carrier resin coating-
{Circle around (1)} After a 50 ml beaker is precisely weighed (measured value A), about 2 g of a sample to be measured is added, and the total mass of the sample and the beaker is precisely weighed (measured value B).
(2) About 20 ml of toluene is put in a beaker and shaken with an ultrasonic shaker for 5 minutes. (At this time, the beaker is installed in the center of the washing tank of the ultrasonic shaker, and the water in the washing tank is reduced to about 150 ml.)
(3) Allow to stand for several minutes after the end of shaking, and flow only the toluene solution in which the resin film is dissolved as waste liquid while holding the sample in the beaker with a magnet from the outside.
(4) While holding the sample in the beaker with a magnet from the outside, put about 20 ml of toluene again into the beaker, and after shaking for 5 minutes with an ultrasonic shaker in the same manner as in the above operation (2), Repeat step (3).
(5) While holding the sample in the beaker with a magnet from the outside, put methanol in a beaker of about 20 ml, move the sample with a magnet, rinse with methanol, and replace the solvent from toluene to methanol.
(6) After leaving still for a few minutes, only methanol is allowed to flow as a waste liquid while the sample in the beaker is held by a magnet from the outside.
(7) The beaker is put into a vacuum dryer, and the substituted methanol is dried and removed (use a vacuum dryer with a solvent trap, temperature 50 ° C., vacuum degree 60 mmHg (0.008 MPa) or less, drying time Perform in 30 minutes).
(8) Take out the beaker from the vacuum dryer, leave it to cool for about 20 minutes, and then weigh the mass precisely (measured value C).
(9) From the measured values obtained as described above, the resin coating amount (% by mass) is calculated according to the following formula.
Resin coating amount = (initial sample mass−sample mass after coating removal) / sample mass × 100
In the above formula, the sample mass is obtained by calculating (measured value B-measured value A), and the sample mass after film peeling is obtained by calculating (measured value C-measured value A).
[0081]
In the operation of each precision balance, it is desirable to obtain up to the fourth decimal place after the decimal point.
The measurement of the resin coating amount of the carrier is preferably carried out twice by the above method, the average value is obtained, and this is used as the measurement value. At this time, when the two measurement values are separated by 0.1% by mass or more, it is desirable to further perform the third measurement and use the average value as the measurement value.
[0082]
Examples of the matrix resin used for the resin coating layer include polyolefin resins such as polyethylene and polypropylene; polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether or Polyvinyl resins such as polyvinyl ketone or polyvinylidene resins; vinyl chloride-vinyl acetate copolymers; styrene-acrylic acid copolymers; straight silicone resins composed of organosiloxane bonds or modified products thereof; polytetrafluoroethylene, polyfluoride Fluorine resins such as vinyl, polyvinylidene fluoride, and polychlorotrifluoroethylene; silicone resins; polyesters; polyurethanes; Over preparative resins; phenolic resins; - include known resin itself, such as; epoxy resins urea-formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, amino resins such as polyamide resins. These resins may be used alone or in combination of two or more.
[0083]
In the present invention, it is preferable to use at least a fluorine-based resin and / or a silicone resin among these resins as the carrier coating resin. The use of at least a fluorine-based resin and / or a silicone resin as the resin is advantageous in that it has a high effect of preventing carrier contamination (impact) due to toner and external additives.
[0084]
It is desirable that at least resin particles and / or conductive particles are dispersed in the coating resin.
Examples of the resin particles include thermoplastic resin particles and thermosetting resin particles. Among these, a thermosetting resin is preferable from the viewpoint that the hardness can be relatively easily increased, and resin particles made of a nitrogen-containing resin containing N atoms are preferable from the viewpoint of imparting negative chargeability to the toner. In addition, these resin particles may be used individually by 1 type, and may use 2 or more types together.
[0085]
The average particle diameter of the resin particles is preferably about 0.1 to 2 μm, more preferably 0.2 to 1 μm. If the average particle size of the resin particles is less than 0.1 μm, the resin particles may not be sufficiently dispersible in the resin coating, whereas if the average particle size exceeds 2 μm, the resin particles may easily fall off from the resin coating. , May not show the original effect.
[0086]
Examples of the conductive particles include metal particles such as gold, silver, and copper; semiconductive oxide particles such as carbon black particles, titanium oxide, and zinc oxide; titanium oxide, zinc oxide, barium sulfate, aluminum borate, And particles having the surface of potassium titanate powder or the like covered with tin oxide, carbon black, metal or the like. These electroconductive particles may be used individually by 1 type, and may use 2 or more types together. Among these, carbon black particles are preferable in terms of production stability, cost, conductivity, and the like. The type of carbon black that can be used as the conductive particles is not particularly limited, but carbon black having a DBP oil absorption of about 50 to 250 ml / 100 g is preferable because of excellent production stability.
The content of the conductive particles is preferably in the range of 1 to 50 parts by mass and more preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the coating resin.
[0087]
In the present invention, the method for forming the coating resin layer of the carrier is not particularly limited. For example, the resin particles such as crosslinkable resin particles and / or styrene-acrylic as the conductive particle matrix resin. Examples thereof include a method in which a coating resin layer forming liquid containing a resin, a fluorine-based resin, a silicone resin, or the like in an appropriate solvent is applied and formed on the surface of the core material. Specifically, the coating and forming methods include an immersion method in which the core material is immersed in the film forming liquid, a spray method in which the film forming liquid is sprayed on the surface of the carrier core material, and the carrier core material is fluidized. Examples thereof include a kneader coater method in which the coating liquid is mixed in a state of being floated by air and the solvent is removed. Among these, the kneader coater method is preferable in the present invention.
[0088]
The solvent used in the coating resin layer forming liquid is not particularly limited as long as it can dissolve only the resin as a matrix resin, and can be selected from known solvents. For example, aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane;
[0089]
When the resin particles and the like are dispersed in the coating resin layer, the resin particles and the resin particles as matrix resin are uniformly dispersed in the thickness direction and the tangential direction of the carrier surface. Even when the coating resin is worn out over a long period of time, the same surface state as when not in use can always be maintained, and a good charge imparting ability for the toner can be maintained over a long period of time.
[0090]
In addition, when the conductive particles are dispersed in the coating resin layer, the conductive particles are uniformly dispersed in the thickness direction and the tangential direction of the carrier surface. Even when the coating resin is worn, the same surface state as when not in use can always be maintained, and carrier deterioration can be prevented for a long time. In addition, when both the said resin particle and the said electroconductive particle are disperse | distributed to the said coating resin layer, both the above-mentioned effects will be show | played simultaneously.
[0091]
The average film thickness of the resin coating layer is usually in the range of 0.1 to 10 μm, but in the present invention, it is in the range of 0.5 to 3 μm in order to develop a stable volume resistivity of the carrier over time. It is preferable.
[0092]
The volume resistivity of the carrier produced as described above corresponds to the upper and lower limits of a normal development contrast potential in order to achieve high image quality. ³ -10 ⁴ In the range of V / cm, 10 ⁶ -10 ¹⁴ A range of Ωcm is preferable. The volume resistivity of the carrier is 10 ⁶ If it is less than Ωcm, the reproducibility of fine lines is poor, and toner fogging on the background due to charge injection tends to occur. The volume resistivity of the carrier is 10 ¹⁴ If it is larger than Ωcm, black solid and halftone reproduction will be worse. In addition, the amount of carrier transferred to the photoconductor increases and the photoconductor is easily damaged.
[0093]
(Developer, replenishment developer)
The developer used in the present invention is prepared by mixing the above carrier and toner in an appropriate blending ratio together with the initial developer and the replenishment developer.
The carrier content ((carrier) / (carrier + toner) × 100) in the initial developer is preferably in the range of 1 to 20% by mass, more preferably in the range of 3 to 15% by mass, and still more preferably 4 It is the range of -10 mass%.
[0094]
On the other hand, the carrier content in the replenishment developer is in the range of 10 to 50% by mass, and preferably in the range of 15 to 45% by mass. When the carrier content is less than 10% by mass, it is not possible to exert sufficient effects for suppressing charging deterioration, preventing resistance change, and consequently suppressing image quality change. Further, the developer that becomes excessive in the developing device is recovered from the inside of the developing device. However, when the carrier content in the replenishing toner is more than 50% by mass, the recovered amount is large. It is necessary to increase the capacity of the container for storage, which is not suitable for downsizing of an apparatus that requires space constraints.
[0095]
It should be noted that the ratio of the recycled toner in the total amount of replenished toner in the present invention is that the amount of toner in the replenishment developer used is clear. It can be determined by measuring the developer amount.
[0096]
Further, as the carrier, a carrier in the developer recovered from the inside of the developing device by the trickle developing method described above can be used as a recycled carrier.
As a method for separating the carrier from the developer collected from the developing device, a blow-off method (a method in which strong air is applied to the electrostatic charge image developer, sieved and only the toner is blown off to separate the carrier), air classification, water washing It can be separated by a method such as a method. The obtained recycled carrier may be used as it is as a developer carrier for initial (start) or replenishment (for trickle replenishment) in a trickle development type image forming apparatus, or a new (unused) carrier. It may be used after mixing with.
[0097]
<Photoconductor>
Next, the photoconductor (electrostatic latent image carrier) used in the present invention will be described.
The photoreceptor used in the present invention has at least a function of forming an electrostatic latent image. The photoreceptor may be a single-layer type electrophotographic photoreceptor in which a charge generation material vapor-deposited film or the like is formed on the surface of the conductive support. In the present invention, the charge generation layer and the charge are formed on the surface of the conductive support. A function-separated multilayer electrophotographic photoreceptor having a transport layer or the like can be suitably used. Further, a photoconductor including a cross-linked resin in which the surface layer of the photoconductor has a charge transporting property and has a siloxane bond is more preferable because it is difficult to wear and can achieve a long life.
In this case, the surface protective layer may be a surface layer, the charge transport layer or the charge generation layer may be a surface layer, and the single-layer type photosensitive layer may be a surface layer.
[0098]
The crosslinked resin having a charge transporting property and having a siloxane bond is particularly preferable in terms of transparency, dielectric breakdown resistance, light stability, and the like.
The crosslinked resin having a siloxane bond is a resin obtained by three-dimensionally crosslinking siloxane, dimethylsiloxane, methylphenylsiloxane, and other necessary components. In the present invention, an organic group F derived from a photofunctional compound is used. A crosslinked resin having a siloxane bond containing a compound containing a flexible organic subunit D and a substituted silicon group A having a hydrolyzable group, in addition to the above-mentioned features, such as wear resistance, charge transportability, etc. It is particularly excellent and preferable.
[0099]
The above A is -Si (R ₁ ) _(3-a) Q _a Represents a substituted silicon group having a hydrolyzable group represented by (wherein R ₁ Represents hydrogen, an alkyl group, a substituted or unsubstituted aryl group, and Q represents a hydrolyzable group. a represents an integer of 1 to 3). b represents an integer of 1 to 4;
[0100]
The organic group F derived from the photofunctional compound is preferably a group having a hole transporting ability or a group having an electron transporting ability. Specifically, the group having an electron transporting ability is specifically a quinone group. Examples thereof include organic groups derived from compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, ethylene compounds, and the like. Specific examples of the group having a hole transporting ability include triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and quinone compounds. Examples thereof include structures having photocarrier transport properties such as compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, and ethylene compounds.
[0101]
The substituted silicon group A having a hydrolyzable group is -Si (R ₁ ) _(3-a) Q _a Represents a substituted silicon group having a hydrolyzable group represented by the following formula. This substituted silicon group undergoes a cross-linking reaction with each other by a Si group, and thus a three-dimensional Si—O—Si bond, that is, an inorganic glass. To form a quality network. Furthermore, the flexible organic subunit D is for connecting F for imparting photoelectric characteristics to a three-dimensional inorganic glassy network by direct bonding. In addition to the rigidity, the inorganic glassy network having brittleness is imparted with an appropriate flexibility, thereby improving the strength as a film. Specifically, −C when n is an integer from 1 to 15. _n H _2n -, -C _n H _(2n-2) -, -C _n H _(2n-4) A divalent hydrocarbon group represented by-, -COO-, -S-, -O-, -CH ₂ -C ₆ H ₄ -, -N = CH-,-(C ₆ H ₄ )-(C ₆ H ₄ )-, Combinations thereof, or those having a substituent introduced therein.
[0102]
Among the compounds containing F, D, and A, the compound in which F is represented by the general formula (II) exhibits particularly excellent hole transportability and mechanical properties. Ar in the general formula (II) ₁ ~ Ar ₄ Each independently represents a substituted or unsubstituted aryl group, and specifically, those listed in Structure Group 1 below are preferred.
[0103]
[Chemical 1]

[0104]
In general formula (II), Ar ₁ ~ Ar ₄ Each independently represents a substituted or unsubstituted aryl group, Ar ₅ Represents a substituted or unsubstituted aryl group or an arylene group. However, Ar ₁ ~ Ar ₅ 1-4 of them have a bond that can be bonded to the bonding group represented by -DA in the compound containing F, D, and A. k represents 0 or 1;
[0105]
[Chemical 2]

[0106]
Among the above, Ar is preferably those listed in Structural Group 2 below.
[0107]
[Chemical 3]

[0108]
The Z ′ is preferably those listed in the following structural group 3.
[0109]
[Formula 4]

[0110]
Where R ₆ Is a phenyl group substituted with hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or an unsubstituted phenyl group, or a group having 7 to 10 carbon atoms Represents an aralkyl group. R ₇ ~ R ₁₃ Is hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, or an unsubstituted phenyl group, 7 to 10 carbon atoms Represents an aralkyl group, halogen. m and s each independently represent 0 or 1, q and r each independently represent an integer of 1 to 10, and t and t ′ each independently represents an integer of 1 to 3. Here, X is the same as the above -D-A.
[0111]
The W is preferably those listed below in the structural group 4.
[0112]
[Chemical formula 5]

[0113]
Here, s ′ represents an integer of 0 to 3.
[0114]
Ar in the general formula (II) ₅ As a specific structure, when k = 0, the above Ar ₁ ~ Ar ₄ When the structure of m = 1 is k = 1, the above Ar ₁ ~ Ar ₄ In which m = 0.
[0115]
The photofunctional organosilicon compound containing F, D, and A may be used alone or in combination of two or more.
In forming the surface layer, it is preferable to add at least one compound having a group capable of binding to the compound containing F, D and A for the purpose of further improving the mechanical strength of the cured film.
[0116]
The group capable of binding to the compound containing F, D and A means a group capable of binding to a silanol group generated when the compound containing F, D and A is hydrolyzed. , -Si (R ₁ ) _(3-a) Q _a Means an epoxy group, an isocyanate group, a carboxyl group, a hydroxy group, a halogen and the like. Of these, -Si (R ₁ ) _(3-a) Q _a A compound having a hydrolyzable group, an epoxy group or an isocyanate group represented by the formula (1) is preferred because it has a stronger mechanical strength.
[0117]
Further, as a compound having a group capable of binding to a compound containing F, D and A, those having two or more of these groups in the molecule make the cross-linked structure of the cured film three-dimensional and stronger to the film. This is preferable because it provides mechanical strength. Among these, the compound represented by general formula (III) is mentioned as the most preferred compound example.
[0118]
[Chemical 6]

[0119]
In general formula (III), A ′ represents —Si (R ₁ ) _(3-a) Q _a A substituted silicon group having a hydrolyzable group represented by formula (B), wherein B is at least a group selected from an n-valent hydrocarbon group, an n-valent phenyl group, -NH-, and -O-Si- which may contain a branch; It consists of one or a combination of these. a represents an integer of 1 to 3, and n represents an integer of 2 or more.
[0120]
The compound represented by the general formula (III) is -Si (R ₁ ) _(3-a) Q _a The compound which has two or more substituted silicon groups A 'which have a hydrolysable group represented by these. The Si group portion contained in A ′ reacts with the compound containing F, D, and A or the compound (III) itself to form a Si—O—Si bond to form a three-dimensional crosslinked cured film. To go. Since the compound containing F, D, and A also has the same Si group, it is possible to form a cured film by itself, but the compound (III) has two or more A ′. Therefore, it is considered that the crosslinked structure of the cured film becomes three-dimensional and has a higher mechanical strength. Further, like the D portion in the compound containing F, D, and A, there is also a role of imparting appropriate flexibility to the crosslinked cured film.
As the compound (III), those shown in the following structural group 5 are more preferable.
[0121]
[Chemical 7]

[0122]
In the above formula, T ₁ , T ₂ Represents a divalent or trivalent hydrocarbon group which may be independently branched, and A ′ represents the aforementioned substituent. h, i, and j are integers of 1 to 3, and are selected so that the number of A ′ in the molecule is 2 or more.
[0123]
Specific examples of the compound of the general formula (III) represented by these formulas are shown below, but are not limited thereto.
[0124]
[Chemical 8]

[0125]
The photofunctional organosilicon compound comprising F, D and A may be used alone or in combination of two or more. Further, for the purpose of adjusting the film formability and flexibility of the film, other coupling agents, fluorine compounds and the like may be mixed and used. As such a compound, various silane coupling agents and commercially available silicone hard coat agents can be used.
Moreover, when forming a crosslinked film as a surface protective layer, it is preferable to add an organometallic compound or a curable matrix.
[0126]
These coating solutions are prepared in the absence of a solvent or, if necessary, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, diethyl ether and dioxane. Although it can be used, it preferably has a boiling point of 100 ° C. or less, and can be used by arbitrarily mixing. The amount of the solvent can be arbitrarily set, but if it is too small, the compound containing F, D, and A is likely to be precipitated, so 0.5-30 mass with respect to 1 part by mass of the compound containing F, D, and A. Parts, preferably 1-20 parts by weight.
[0127]
In the preparation of the coating liquid, the compound containing F, D, and A and, if necessary, other compounds are allowed to react with the solid catalyst, but the reaction temperature and time vary depending on the type of raw material, Usually, it is performed at 0 to 100 ° C, more preferably at 0 to 70 ° C, and particularly preferably at a temperature of 10 to 35 ° C. Although there is no restriction | limiting in particular in reaction time, Since it will become easy to produce gelation when reaction time becomes long, it is preferable to carry out in 10 minutes to 100 hours.
[0128]
When a polymer having a group capable of binding to the compound consisting of F, D, and A is added, if a solid catalyst and the polymer are present at the same time, gelation may be significantly promoted, and coating may be difficult. It is preferable to add after removing the solid catalyst. Such a solid catalyst is not particularly limited as long as the catalyst component is insoluble in any of the compound solution containing F, D, and A, other compounds, solvents and the like.
[0129]
The amount of water added during the hydrolytic condensation is not particularly limited, but it preferably affects the storage stability of the product and further suppresses gelation when subjected to polymerization. It is preferably used in a proportion of 30 to 500%, more preferably 50 to 300%, based on the theoretical amount necessary for hydrolyzing all the hydrolyzable groups of the compound. When the amount of water is more than 500%, the storage stability of the product is deteriorated or the product is easily precipitated. On the other hand, when the amount of water is less than 30%, unreacted substances increase and phase separation is likely to occur during coating liquid application and curing, and the strength of the coating film tends to decrease.
[0130]
Further, as a curing catalyst, a protonic acid such as hydrochloric acid, acetic acid, phosphoric acid or sulfuric acid is added and cured. The curing temperature can be arbitrarily set, but is set to 60 ° C. or higher, more preferably 80 ° C. or higher in order to obtain a desired strength. Although hardening time can be arbitrarily set as needed, 10 minutes-5 hours are preferable. It is also effective to stabilize the characteristics after the curing reaction by maintaining a high humidity state. Furthermore, depending on the application, it can be hydrophobized by surface treatment with hexamethyldisilazane, trimethylchlorosilane, or the like.
[0131]
As a coating method, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method can be used.
[0132]
In the photoreceptor used in the present invention, an undercoat layer can be formed between the substrate (conductive support) and the photosensitive layer as desired. As a material used for forming the undercoat layer, a known binder resin conventionally used for the undercoat layer can be used, but it can also be formed by the material constituting the surface layer. it can. In this case, other materials such as a zirconium compound and an electron transporting pigment may be added as desired.
[0133]
In the photoreceptor used in the present invention, when the surface protective layer is provided, any conventionally known photosensitive layer can be adopted as the photosensitive layer formed under the surface protective layer. A laminated photoreceptor having a transport layer laminated thereon or a single-layer photoreceptor containing a charge generating material may be used, but a laminated photoreceptor is preferred from the viewpoint of sensitivity, durability, and the like.
[0134]
The charge generation layer in the multilayer photosensitive layer is formed of at least a charge generation material and a binder resin.
As the charge generation material, all known materials such as azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, perylene pigments, pyrrolopyrrole pigments, and furatocyanine pigments can be used. Metal phthalocyanine pigments are preferred. Among these, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine having specific crystals are particularly preferable. The binder resin can be selected from a wide range of insulating resins.
The blending ratio of the charge generation material and the binder resin (mass ratio) is preferably in the range of 10: 1 to 1:10.
[0135]
As a method for dispersing them, a usual method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or the like can be used, but at this time, it is necessary that the crystal form of the charge generation material does not change due to the dispersion. It is said.
For the above dispersion, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform Ordinary organic solvents such as chlorobenzene and toluene can be used alone or in admixture of two or more.
[0136]
The thickness of the charge generation layer is generally 0.1 to 5 μm, preferably 0.2 to 2.0 μm. In addition, as a coating method used when the charge generation layer is provided, conventional methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Can be used.
[0137]
As the charge transport layer in the photoreceptor used in the present invention, those formed by a known technique can be used. These charge transport layers are formed containing a charge transport material and a binder resin, or are formed containing a polymer charge transport material.
Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds Electron transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Pore-transporting compounds; These charge transport materials can be used alone or in combination of two or more, but are not limited thereto.
[0138]
As the charge transport material, the triphenylamine compound represented by the general formula (IV) and the benzidine compound represented by the general formula (V) have high charge (hole) transport ability and excellent stability. Therefore, it is particularly preferably used.
[0139]
[Chemical 9]

[0140]
In the above formula, R ₁₄ Represents a hydrogen atom or a methyl group. N is 1 or 2. Ar ₆ And Ar ₇ Each independently represents a substituted or unsubstituted aryl group, and the substituent is a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 carbon atom. Represents a substituted amino group substituted with an alkyl group in the range of ˜3.
[0141]
Embedded image

[0142]
R in the above formula ₁₅ , R ₁₅ Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ₁₆ , R ₁₆ ', R ₁₇ , R ₁₇ Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an amino group substituted with an alkyl group having 1 to 2 carbon atoms. m and n are each independently an integer of 0 to 2.
These can be used alone or in admixture of two or more. A polymer charge transport material can also be used.
[0143]
As the binder resin used for the charge transport layer, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride- Examples include acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin. .
[0144]
The binder resins can be used alone or in combination of two or more. The blending ratio (mass ratio) of the charge transport material and the binder resin is preferably in the range of 10: 1 to 1: 5. The thickness of the charge transport layer is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 30 μm. As a coating method, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method can be used.
[0145]
Furthermore, as a solvent, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride; tetrahydrofuran, Ordinary organic solvents such as cyclic or linear ethers such as ethyl ether; and the like can be used alone or in admixture of two or more.
[0146]
As the conductive support, aluminum is generally used in an appropriate shape such as a drum shape, a sheet shape, or a plate shape, but is not limited thereto. When the photosensitive drum is used in a laser printer, the surface of the support has a center line average roughness R in order to prevent interference fringes generated when laser light is irradiated. _a75 The surface is preferably roughened so that the value is in the range of 0.04 μm to 0.5 μm. As the roughening method, wet honing performed by suspending an abrasive in water and spraying the support, or centerless grinding in which the support is pressed against a rotating grindstone and continuously subjected to grinding is preferable. . R _a75 If the value is smaller than 0.04 μm, the effect of preventing interference cannot be obtained because it is close to a mirror surface, and R _a75 When the value is larger than 0.5 μm, even if a film is formed as the undercoat layer, the image quality becomes rough and is not suitable. When non-interfering light is used for the light source, it is not particularly necessary to roughen the interference fringes, and it is possible to prevent the occurrence of defects due to the unevenness of the surface of the base material, which is suitable for longer life.
[0147]
In the photoreceptor used in the present invention, when the surface protective layer is not provided, the outermost surface layer of the photosensitive layer formed on the surface of the conductive support is the surface layer of the photoreceptor used in the present invention. . There are two types of photosensitive layers, a laminated type and a single layer type.
[0148]
In the case of a laminated type photosensitive layer, the charge transport layer is the surface layer if the charge transport layer is the surface, and the charge generation layer is the surface layer if the charge generation layer is the surface. In this case, instead of the structure of the charge transport layer or the charge generation layer, the structure of the layer described as the surface layer is employed for the outermost surface layer, and the structure described above is employed as it is for the other layers. .
[0149]
On the other hand, in the case of a single-layer type photosensitive layer, the photosensitive layer itself is a layer constituting the surface layer. However, it is necessary to add a charge generating material to the single-layer type photosensitive layer. As the charge generation material, the same material as that of the charge generation layer described above can be used.
[0150]
<Image forming apparatus>
In the image forming method of the present invention, at least charging means for charging the surface of the electrostatic latent image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier. Developing means for developing the electrostatic latent image as a toner image using a developer; transfer means for transferring the toner image to a transfer target; and toner remaining on the surface of the electrostatic latent image carrier after transfer. An image forming apparatus having a cleaning unit that removes and a fixing unit that fixes the transferred toner image onto a recording medium is used.
[0151]
In the present invention, the developing unit has a developer recovery mechanism for appropriately replenishing a developer for replenishment composed of the toner and a carrier inside the developing device and for collecting the excess developer from the inside. That is, the trickle development method is adopted. If at least one developing unit adopts the trickle developing method, the maintenance of the developer can be saved and further maintenance-free can be realized. Of course, the trickle developing method can be adopted for more developing units. Desirably, it is most desirable to employ all developing means.
[0152]
The developer for replenishment in the trickle development method is usually mixed in the developer, and thus is replenished by a certain amount as the toner is consumed. Further, as a general control method, there is a method in which the replenishment developer is replenished and controlled so that the toner concentration is within a certain range by a toner concentration sensor in the developing device. Further, the developer in the developing device that has become excessive due to replenishment is usually recovered by overflow and stored in a recovery container.
[0153]
In the image forming method of the present invention, when creating a full color image, the color toner image of each color is applied to the surface of an intermediate transfer belt or intermediate transfer drum as a transfer target from the viewpoint of versatility of paper and high image quality. Once transferred and laminated, the laminated color toner images are preferably transferred onto the surface of a recording medium such as paper at once. Of course, it is also possible to use a recording medium such as paper as a transfer medium and directly laminate color toner images of respective colors.
[0154]
As described above, the image forming method of the present invention is effective in the high-speed image forming apparatus. The process speed to which the present invention can be applied is preferably in the range of 100 to 350 mm / sec, and more preferably in the range of 160 to 280 mm / sec.
[0155]
The cleaning means is means for removing residual toner remaining as transfer residue on the surface of the latent electrostatic image bearing member after transfer. By this cleaning means, a blade, a brush, a roll or the like can be brought into direct contact with the surface of the electrostatic latent image carrier to remove toner, paper dust, dust, etc. adhering to the surface of the electrostatic latent image carrier.
[0156]
The most commonly employed cleaning means is a cleaning blade in which a rubber blade such as polyurethane is pressed against the electrostatic latent image carrier. On the other hand, a magnet is fixedly arranged inside, a rotatable cylindrical non-magnetic sleeve is provided on the outer periphery, and a magnetic carrier that carries a magnetic carrier on the sleeve surface to collect toner, or a semiconductive Alternatively, an electrostatic brush may be used in which the resin fibers or animal hairs are rotatable in a roll shape, and a bias having a polarity opposite to that of the toner is applied to the roll to remove the toner.
In the present invention, a cleaning blade is preferably used for toner recycling.
[0157]
The image forming apparatus used in the present invention further includes a recycling unit. The recycling means is means for transferring the toner collected by the cleaning means to a developing device having a developer carrying member.
The image forming method of the present invention having this recycling means can be carried out using an image forming apparatus such as a toner recycling system type copier, printer, facsimile machine or the like.
[0158]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the description of the toner and the carrier, “part” means “part by mass” unless otherwise specified.
[0159]
First, the toner, carrier, and developer used in Examples and Comparative Examples will be described.
<Each measurement method>
In the production of the following toner, carrier, and developer, each measurement was performed by the following method.
[0160]
(Measurement of volume resistivity of external additives and carriers)
As shown in FIG. 1, the measurement sample 3 is sandwiched between the lower electrode 4 and the upper electrode 2, the thickness L is measured with a dial gauge while pressing from above, and the electrical resistance of the measurement sample 3 is measured by the high voltage ohmmeter 6. Measured with.
[0161]
Specifically, a sample of specific titanium oxide as an external additive was added to a sample machine with a molding machine at 4.9 × 10. ⁷ A measurement disk was prepared by applying a pressure of Pa. Next, the surface of the measurement disk was cleaned with a brush, sandwiched between the upper electrode 2 and the lower electrode 4 in the cell, and the thickness was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity value.
[0162]
In the case of a carrier, the sample was filled in the lower electrode 4 having a diameter of 100 mm, the upper electrode 2 was set, a load of 3.43 kg was applied from above, and the thickness L was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity value.
[0163]
The calculation formula for the volume resistivity (Ω · cm) is as shown in the following formula.
R = α × E / (I−I ₀ ) / L
In the above formula, R is a volume specific resistance value (Ω · cm), E is an applied voltage (V), I is a current value (A), I ₀ Represents the current value (A) at an applied voltage of 0 V, and L represents the thickness (mm) of the sample layer. The coefficient of α is the area of the electrode plate (cm ² ).
[0164]
(Toner shape factor SF1)
In the present invention, the toner shape index SF1 means an average value of values calculated by the following formula for individual toner particles as described above.
SF1 = (ML ² / A) × (π / 4) × 100
In the above equation, ML represents the maximum toner length, and A represents the projected area of the toner. It means the value calculated by the following formula. In the case of a true sphere, SF1 = 100.
[0165]
As a specific method for obtaining the shape index, a toner image is taken from an optical microscope into an image analyzer (LUZEX III: manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and area are calculated. This was done by determining the value of SF1 in the above formula for each particle.
[0166]
(Toner charge measurement)
The toner charge amount in an actual machine evaluation test described later was measured with a TB200 manufactured by Toshiba under the conditions of 25 ° C. and 55% RH in the same manner as above, by collecting about 2 g of the developer on the mag sleeve in the developing device. The measured toner concentration of each developer was about 10% by mass.
[0167]
<Manufacture of photoconductor A>
A drawn tube made of JIS A3003 alloy having a diameter of 84 mm and a length of 340 mm was prepared and polished by a centerless polishing apparatus to obtain a cylinder having a 10-point average roughness Rz of 0.6 μm. As a cleaning step, the cylinder was degreased, etched with a 2% by mass sodium hydroxide solution for 1 minute, neutralized, and further washed with pure water.
[0168]
Next, as an anodizing treatment step, an anodized film (current density: 1.0 A / dm) is formed on the cylinder surface with a 10% by mass sulfuric acid solution. ² ) Was formed. After washing with water, it was immersed in a 1% by mass nickel acetate solution at 80 ° C. for 20 minutes for sealing treatment. Further, pure water washing and drying treatment were performed. In this way, an aluminum substrate (conductive support) having an anodized film having a thickness of 7 μm formed on the surface of the aluminum cylinder was obtained.
[0169]
One part of chlorogallium phthalocyanine having a strong diffraction peak at 7.4 °, 16.6 °, 25.5 °, 28.3 ° in the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum, A polyvinyl butyral (ESREC BM-S: manufactured by Sekisui Chemical Co., Ltd.) and 100 parts of n-butyl acetate were mixed together and treated with a glass bead for 1 hour and dispersed to prepare a coating solution. The obtained coating solution was applied on the surface of the anodized film of the aluminum base material by a dip coating method and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.
[0170]
2 parts of a benzidine compound represented by the following formula (1) (wherein Me represents a methyl group) and 3 parts of a polymer compound (viscosity average molecular weight: 39,000) having the following formula (2) as a basic unit, A coating solution dissolved in 20 parts of chlorobenzene was applied to the surface of the charge generation layer by a dip coating method, and heated at 110 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm.
[0171]
Embedded image

[0172]
Among the compounds represented by the following general formula (II), 2 parts of the compound (3) each having a structure shown in Table 1 (wherein iPr represents an isopropyl group), 2 parts of methyltrimethoxysilane, Tetramethoxysilane 0.5 part, colloidal silica 0.3 part is dissolved in isopropyl alcohol 5 parts, tetrahydrofuran 3 parts, distilled water 0.3 part, and ion exchange resin (Amberlyst 15E) 0.5 part is added, The hydrolysis was carried out for 24 hours by stirring at room temperature.
[0173]
Embedded image

[0174]
[Table 1]

[0175]
0.04 part of aluminum trisacetylacetonate and 0.1 part of 3,5-di-t-butyl-4-hydroxytoluene (BHT) with respect to 2 parts of the liquid obtained by separating the ion exchange resin from the hydrolyzed product Was added to prepare a surface protective layer coating solution. This coating solution was applied on the charge transport layer by a ring-type dip coating method. After air-drying at room temperature for 30 minutes, it was cured by heat treatment at 170 ° C. for 1 hour to form a surface protective layer having a film thickness of about 3 μm, whereby Photoreceptor A was produced.
[0176]
<Production of toner>
(Preparation of toner particles 1)
Styrene-nbutyl acrylate copolymer resin (copolymerization ratio: 70/30, Tg: 58 ° C., Mn: 4,000, Mw: 25,000) 100 parts
・ Carbon black (Mogal L: Cabot) 3 parts
[0177]
The mixture of the above components is kneaded with an extruder, pulverized with a jet mill, and then dispersed with a wind classifier. Toner particles 1 having a volume average particle diameter D50 of 7.8 μm and a shape factor SF1 of 148.8 ( Black).
[0178]
(Preparation of toner particles 2)
・ Linear polyester (Linear polyester selected from terephthalic acid / bisphenol A / ethylene oxide adduct / cyclohexanedimethanol, Tg: 62 ° C., Mn: 4,000, Mw: 35,000, acid value: 12, hydroxy acid Price: 25) 86 parts Carbon black (R330: manufactured by Cabot) 8 parts
-Polyethylene wax (melting point: 135 ° C) 6 parts
[0179]
After kneading the mixture of the above components with an extruder, pulverizing with a surface pulverization type pulverizer, fine particles and coarse particles are classified with an air classifier, and the process of obtaining particles of intermediate size is repeated three times. Toner particles 2 (black) having a volume average particle diameter D50 of 8 μm and a shape factor SF1 of 128.5 were obtained.
[0180]
<Creation of carrier>
(Preparation of carrier A)
-Ferrite particles (volume average particle size: 50 μm) 100 parts
・ Toluene 14 parts
-Styrene-methacrylate copolymer (component ratio: 90/10, weight average molecular weight: 70,000) 2 parts
・ Carbon black (R330: Cabot Corporation) 0.2 parts
[0181]
First, each of the above components excluding ferrite particles is stirred with a stirrer for 10 minutes to prepare a dispersed coating resin solution. Next, the coating resin solution and the ferrite particles are placed in a vacuum degassing kneader, and 60 After stirring for 30 minutes at 0 ° C., carrier A was obtained by further depressurizing while heating and degassing and drying.
This carrier has a volume resistivity value of 5.0 × 10 at the time of an applied electric field of 1000 V / cm. ¹¹ It was Ωcm.
[0182]
(Preparation of carrier B)
-Ferrite particles (volume average particle size: 50 μm) 100 parts
・ Toluene 14 parts
-Styrene-methacrylate copolymer (component ratio: 90/10, weight average molecular weight: 70,000) 2 parts
・ Carbon black (VXC72: Cabot Corporation) 0.2 parts
・ 0.2 parts of crosslinked melamine resin
[0183]
First, each of the above components excluding ferrite particles is stirred with a stirrer for 10 minutes to prepare a dispersed coating resin solution. Next, the coating resin solution and the ferrite particles are placed in a vacuum degassing kneader, and 60 After stirring at 30 ° C. for 30 minutes, carrier B was obtained by further depressurizing while heating and degassing and drying.
This carrier has a volume resistivity of 7.0 × 10 at an applied electric field of 1000 V / cm. ¹¹ It was Ωcm.
[0184]
(Preparation of carrier C)
Ferrite particles (volume resistance value: 10 ⁸ Ω · cm, volume average particle diameter: 50 μm) 100 parts
・ Toluene 14 parts
-Perfluorooctylethyl acrylate / methyl methacrylate copolymer (copolymerization ratio 40:60, Mw: 50,000) 1.6 parts
・ Carbon black (VXC-72: Cabot Corporation) 0.12 parts
-Cross-linked melamine resin (number average particle size: 0.3 μm) 0.2 parts
[0185]
Among the above components, the components excluding the ferrite particles are dispersed with a stirrer for 10 minutes to prepare a coating resin layer forming solution. The coating resin layer forming solution and the ferrite particles are placed in a vacuum degassing kneader, 60 After stirring for 30 minutes at a temperature, toluene was distilled off under reduced pressure to form a coating resin layer on the surface of the ferrite particles, and carrier A was produced.
[0186]
The perfluorooctylethyl acrylate / methyl methacrylate copolymer used as the matrix resin in the resin coating layer was obtained because carbon black particles and crosslinked melamine resin particles were diluted with toluene and dispersed in a sand mill. Each particle of carbon black and cross-linked melamine resin was uniformly dispersed in the resin coating on the carrier.
This carrier has a volume resistivity of 2 × 10 at an applied electric field of 1000 V / cm. ¹² It was Ωcm.
[0187]
(Production of carriers D and E)
6 parts of the toner particles 1 and 94 parts of the carrier C were mixed to prepare developer A. Using the developer C thus obtained, a copy test was performed with an electrophotographic copying machine (manufactured by Fuji Xerox Co., Ltd., Color DocuTech 60 modified machine). Two levels of 50,000 copies and 100,000 copies were taken, and deteriorated developer D (50,000 sheets) and developer E (100,000 sheets) were taken out. Thereafter, the toner and the carrier were separated by a blow-off method. The carrier separated from developer B was designated as carrier D, and the carrier separated from developer E was designated as carrier E.
Carriers D and E each have a volume resistivity of 8 × 10 at an applied electric field of 1000 V / cm. ¹¹ Ωcm, 5 × 10 ¹⁰ It was Ωcm.
[0188]
(Preparation of carrier F)
The surface of carrier D was forcibly roughened (forced deterioration) with a sample mill, and carrier F having a surface exposure amount of the core component of the carrier of 37.1 atom% was produced.
This carrier has a volume resistivity of 3 × 10 at an applied electric field of 1000 V / cm. ⁹ It was Ωcm.
[0189]
(Preparation of carrier G)
The surface of carrier D is forcibly roughened with a sample mill (forced deterioration), and the resin coverage (C / C ₀ ) Was produced with a carrier G of 0.46 with respect to the carrier D, which is a new carrier.
[0190]
Table 2 clearly shows the regeneration conditions and physical properties of the carriers C to G.
In Table 1, the surface exposure amount of the core component, the resin coverage, and the volume electrical resistance of the core material were measured by the procedures given as examples of the measurement procedure described above. Resin coverage (C / C ₀ ) A new (unused) carrier resin coating amount C used as a basis for calculation ₀ Is a value measured for the carrier before the copy test or before the forced deterioration (the carrier C has not been subjected to the copy test or the forced deterioration, so the resin coverage remains unused, and C = C ₀ That is, C / C ₀ Is 1).
[0191]
[Table 2]

[0192]
<Production of developer>
To 100 parts of each of the toner particles 1 and 2, 0.8 parts of hydrophobic titania treated with decylsilane having an average particle diameter of 15 nm and 1.3 parts of hydrophobic silica (NY50, manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 30 nm are added. Then, after blending for 10 minutes at a peripheral speed of 32 m / sec using a Henschel mixer, coarse particles were removed using a sieve having a mesh size of 45 μm, and toners 1 and 2 were obtained.
[0193]
100 parts of the various carriers and 6 parts of the toners were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain various developers.
[0194]
<Preparation of replenishment developer>
The toner was mixed at a ratio of 10 parts of the various carriers to 100 parts of the toner. This was used as a replenishment developer.
[0195]
<Example 1>
A developer 1 composed of the toner 1 and the carrier A and a replenishment developer 1 composed of the toner 1 and the carrier B were prepared.
The original photoconductor (organic photoconductor) of the Color DocuTech60 remodeling machine manufactured by Fuji Xerox, in which recycled toner is returned to the toner replenishment section, is replaced with photoconductor A made of a cross-linked resin having a siloxane bond in the surface layer. The replenishment developer 1 was accommodated in a developer cartridge, and the developer 1 was accommodated in a developing unit, and a long-term use test was conducted to evaluate fogging, image flow, and the like.
[0196]
The Color DocuTech 60 remodeling machine forms an electrostatic latent image on the surface of the electrostatic latent image carrier, the electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, and An electrostatic latent image forming means and a developer composed of a toner and a carrier are accommodated therein, and the electrostatic latent image is developed by the developer layer formed on the surface of the developer carrying member. An image forming apparatus including a developing unit that forms a toner image on the surface of an image carrier, a transfer unit that transfers the toner image to an intermediate transfer member, and a cleaning unit that uses a cleaning blade method. Yes.
The process speed was 260 mm / sec.
[0197]
At this time, a toner band was formed on the surface of the latent electrostatic image bearing member for every fixed number of prints, and the toner band was controlled to be recovered by the cleaning device without being transferred. This toner band formation frequency was changed so that the ratio of the recycled toner in the total amount of replenished toner supplied from the toner cartridge was adjusted to 15% by mass when 5000 A4 size images were printed from the beginning.
[0198]
The ratio of the recycled toner in the total amount of the replenished toner includes the amount of recycle toner collected by the toner replenishment unit and the amount of replenishment developer replenished into the developer from the replenishment developer cartridge for every fixed number of prints. Was determined by measuring each of the evaluators while they were driven for 1 minute.
[0199]
From 5000 sheets, printing was performed up to 100,000 sheets while maintaining the above conditions, and the toner charge amount and image quality (fogging on paper, image flow) at that time were evaluated. Note that fog on paper and image flow were evaluated according to the following criteria.
[0200]
-Fog on paper-
The fog in the non-image area of the printed image was visually sensory evaluated and determined as follows.
・ ○ ・ ・ ・ Not dirty at all.
・ △ ・ ・ ・ Slightly dirty but acceptable level.
······· Soiled so that the boundary between the non-development area (margin) and the non-image area can be seen.
[0201]
-Image flow-
The fog in the non-image area of the printed image was visually sensory evaluated and determined as follows.
・ ○ ・ ・ ・ There is no flow.
・ × ... Flow is seen.
The results are shown in Table 3.
[0202]
<Example 2>
In Example 1, evaluation was performed in the same manner as in Example 1 except that the ratio of the recycled toner in the replenished toner after printing 5000 sheets was 20% by mass. The results are shown in Table 3.
[0203]
<Example 3>
Evaluation was conducted in the same manner as in Example 1 except that the ratio of the recycled toner in the replenishing toner after printing 5000 sheets was adjusted to 25% by mass. The results are shown in Table 3.
[0204]
<Comparative Example 1>
Evaluation was performed in the same manner as in Example 1 except that the amount of recycled toner in the replenishing toner after printing 5000 sheets was adjusted to 10% by mass. The results are shown in Table 3.
[0205]
<Comparative Examples 2-5>
In Examples 1 to 3 and Comparative Example 1, the same procedure was applied except that the trickle developing method of the Color DocuTech 60 remodeling machine, which was the evaluation machine, was changed to a toner replenishing method (replenishment toner was the toner used for each developer). Evaluation was performed. The results are shown in Table 3.
[0206]
[Table 3]

[0207]
<Example 4>
A developer 2 composed of the toner 2 and the carrier A and a replenishment developer 2 composed of the toner 2 and the carrier B were prepared.
In Example 1, evaluation was performed in the same manner as in Example 1 except that the developer 2 and the replenishment developer 2 were used instead of the developer 1 and the replenishment developer 1. The results are shown in Table 4.
[0208]
< Example 5 >
Evaluation was conducted in the same manner as in Example 4 except that the ratio of the recycled toner in the replenishing toner after printing 5000 sheets was adjusted to 20% by mass. The results are shown in Table 4.
[0209]
<Example 6>
Evaluation was performed in the same manner as in Example 4 except that the amount of recycled toner in the replenishing toner after printing 5000 sheets was adjusted to 25% by mass. The results are shown in Table 4.
[0210]
<Comparative Example 6>
Evaluation was performed in the same manner as in Example 4 except that the ratio of the recycled toner in the replenished toner after printing 5000 sheets was adjusted to 10% by mass. The results are shown in Table 4.
[0211]
<Comparative Examples 7 to 10>
The same procedure as in Examples 4 to 6 and Comparative Example 6 was performed except that the trickle developing method of the Color DocuTech 60 remodeling machine, which is the evaluation machine, was changed to a toner replenishing method (the replenishing toner was the toner used for each developer). Evaluation was performed. The results are shown in Table 4.
[0212]
[Table 4]

[0213]
As shown in Tables 3 and 4, when the ratio of the recycled toner in the total amount of the replenished toner, which is the image forming method of the present invention, is 15% by mass or more, there is no fog on paper and no image flow of the printed image. It was. On the other hand, when the ratio of the recycled toner in the replenishing toner was 10% by mass, there was fog on paper and the image flow of the printed image, and the image quality was insufficient.
Further, by adopting the trickle development method, good image quality without fogging on paper and image flow of a printed image was obtained over a long period of time.
[0214]
<Examples 7 to 12>
The toner particles 1 and the carriers C to G were sequentially combined and mixed to prepare developers 3 to 7 and replenishment developers 3 to 7.
In the electrophotographic copying machine (Color DocuTech 60 remodeling machine) equipped with the photoreceptor A used in Example 1 above, these developer and replenishment developer are used in combination as shown in Table 5, and recycled toner is used. The copy ratio was adjusted so as to be 15% by mass in any test. The results are shown in Table 5 below.
[0215]
Note that the image quality evaluation of the copy test in Table 5 was performed by first copying a chart with density gradation at the start of the test, and visually evaluating the gradation, density uniformity, and the presence or absence of an edge effect. . The image quality after copying 100,000 sheets was evaluated visually from the viewpoint of graininess, gradation / pseudo contour, density reproducibility, and other image quality defects.
[0216]
[Table 5]

[0217]
【The invention's effect】
According to the present invention, the development unit adopting a so-called trickle development method is provided, and the residual toner collected from the surface of the electrostatic latent image carrier by the cleaning unit is removed from the developing unit or the toner supply unit via the toner collection device. In the image forming method that is returned to the inside and reused as the recycled toner, it is possible to provide an image forming method that continues to provide a high-quality image stably without image defects even in a high-speed process. Further, according to the present invention, it is possible to provide an image forming method capable of stabilizing the cleaning characteristics of the cleaning means and maintaining the characteristics as an electrostatic latent image carrier for a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a method of measuring a volume specific resistance value.
[Explanation of symbols]
1 Guard electrode
2 Upper electrode
3 Measurement sample
4 Lower electrode
5 Sample holding ring
6 Electrometer

Claims (2)

At least charging means for charging the surface of the electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrostatic latent image carrier, and developing the electrostatic latent image Developing means for developing a toner image using an agent, transfer means for transferring the toner image to a transfer target, cleaning means for removing toner remaining on the surface of the electrostatic latent image carrier after transfer, and transferred toner An image forming method for forming an image with an image forming apparatus having a fixing means for fixing an image to a recording medium,
The developing means appropriately replenishes a developer for replenishment containing toner and carrier into a developer containing a developer composed of toner and carrier, and removes the excess developer from the developer. A developer recovery mechanism for recovering from the inside; the toner recovered from the electrostatic latent image carrier by the cleaning means is reused as recycled toner; An image forming method, wherein the ratio of recycled toner is 15% by mass or more. The developer recovered from the inside of the developing device is separated into a carrier and a toner, and the separated carrier is reused as a recycling carrier for the initial developer or the replenishment developer, and the core of the carrier 2. The image forming method according to claim 1, wherein the surface exposure amount of the material component is in the range of 0 to 30 atom%.

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