JP3805106B2 - Image forming method - Google Patents

Description

［式中、Ｘ₁およびＸ₂は水素原子、低級アルキル基、低級アルコキシ基、ニトロ基及びハロゲン原子からなるグループから選択されるメンバーを表示し、Ｘ₁とＸ₂は同じ又は異なっており、ｍおよびｍ’は１〜３の整数を表示し、Ｒ₁およびＲ₃は水素原子、Ｃ₁〜Ｃ₁₈のアルキル基、Ｃ₂〜Ｃ₁₈のアルケニル基、スルホンアミド基、メシル基、スルホン酸基、カルボキシエステル基、ヒドロキシ基、Ｃ₁〜Ｃ₁₈のアルコキシ基、アセチルアミノ基、ベンゾイルアミノ基及びハロゲン原子からなるグループから選択されるメンバーを表示し、Ｒ₁とＲ₃は同じ又は異なっており、ｎおよびｎ’は１〜３の整数を表示し、Ｒ₂およびＲ₄は水素原子またはニトロ基を表示し、Ａ⁺はアンモニウムイオン、水素イオン、ナトリウムイオン、カリウムイオン及びそれらの混合イオンからなるグループから選択されるカチオンイオンを示す。］
【００６９】
本発明によれば、画像解析装置で測定した形状係数ＳＦ−１の値が１００≦ＳＦ−１≦１２０であり、かつＳＦ−２の値が１００≦ＳＦ−２≦１１５であるトナーであり、トナー組成物として特定のアゾ系鉄錯体化合物を用い、トナー粒子に対して０．０１〜３．０重量％の重合体微粒子、及びトナー粒子に対して０．１〜３．０重量％無機微粉体を有するトナーによって、トナー帯電の迅速な立ち上がりによる高品位な画像性と、安定したクリーニング性を得ることが可能である。また、流動性、長期保存性、耐環境特性、耐久性を損なうことなく感光体上カブリを安定的に低減させることが可能である。
【００７０】
また、本発明によれば、本発明中のトナーを一成分接触現像の構成に適用することによって、非磁性一成分現像法においてトナー帯電の迅速な立ち上がりによる高品位な画像性と、安定したクリーニング性を得ることが可能である。
【００７１】
更に、本発明によれば、本発明中のトナーを現像同時クリーニングの構成に適用することによって、転写残トナーによる像担持体の帯電阻害を抑制し、更に、転写残トナーを現像時に回収すると同時に、定着性能と耐久性能を長期にわたり両立できることが可能である。
【００７２】
【発明の実施の形態】
本発明者らは、鋭意検討の結果、各々特定の荷電制御剤及び無機微粒子、重合体微粒子を組み合わせ、トナーに特定の形状を持たせることで、マシンの高速化、長寿命化に対応し得る、流動性、長期保存性、耐環境特性、耐久性を損なうことなく、（特に、低湿環境下での）感光体上カブリを特異に低減させたトナーを得ることを見い出した。また、この効果は、本発明中の重合法のトナーに適用した場合、もしくは本発明中の特定のカーボンブラック及び特定のアゾ系鉄錯体化合物を前分散する工程を行って製造されたトナーにおいて顕著であることを見い出した。
【００７３】
即ち、前述のように無機微粉体と重合体微粒子を併用した方法は、現像が高速化するに連れて、トナーが感光体の非潜像形成部にも極微量ながら付着する現象（感光体上カブリ）が問題となる。非潜像形成部に付着したトナーは転写工程で転写され難く、クリーニング工程を有するプロセスでは、廃トナー量の増大、或いはクリーニング不良の原因となり、クリーニング工程を有さないプロセスでは、帯電器汚れを促進し、現像での転写残トナーの回収に不利となり、帯電不良、回収不良による画像欠陥の原因となる。
【００７４】
また、特定の形状を持たせたトナーに、特定のアゾ系鉄錯体化合物を含有させ、重合体微粒子を添加したトナーは、トナー帯電の迅速な立ち上がりによる高品位な画像性と、感光体上の現像トナーの帯電量を適正に制御し、転写残トナーの過剰帯電によるクリーニング性の低下を防止し得る。更に、特定のカーボンブラックを含有させたトナーは、よりトナー帯電の立ち上がりが迅速となり高品位な画像性を得ることができる。
【００７５】
また、現像同時回収プロセスでは、トナーの帯電部材通過時の帯電制御特性が改善され、転写残トナーよる感光体の帯電阻害を十分に抑制し、転写残トナーを現像時に円滑に回収することが可能となるが、良好な転写性、画像性を得るためには流動性付与剤としての無機微粉体の添加が必須である。しかし、長期間の使用に伴いこの無機微粉体がトナー表面に埋め込まれることで、トナー帯電性の変化、流動性の低下による転写性、画像性の劣化を招く。
【００７６】
特定のアゾ系鉄錯体化合物を含有するトナー粒子に、無機微粉体と重合体微粒子を添加し、特定の形状をトナーに持たせることによって、長期間の使用によっても無機微粉体がトナー表面に埋め込まれることなく、トナー帯電性の変化、流動性の低下のない、優れた転写性、画像性を安定して得ることができる。
【００７７】
同時に、本発明者らは、特定のアゾ系鉄錯体化合物を含有し、重合体微粒子を添加し、特定の形状を持たせたトナーは、トナー帯電の立ち上がりが迅速で、一成分系の帯電付与工程でも低負荷で適正かつ十分なトリボ付与が行われ、感光体上カブリを低減していることを見い出した。
【００７８】
そのメカニズムは必ずしも明確ではないが、以下のように推測される。
【００７９】
即ち、通常重合体微粒子は、一次微粒子が数十個から数千個集まって凝集体を形成している。重合体微粒子の凝集体は、球形もしくは球形に近い形である一次粒子形状、トナー粒子に対して嵩密度が高いことによって、トナー粒子と均一混合する工程においても、効果的なシェアをかけることが出来ないために、好ましく崩壊しないものが残存する場合が多い。
【００８０】
この混合工程で、崩壊しなかった重合体微粒子の凝集体が現像工程で摩擦帯電する際に崩壊し、そのとき近傍にいたトナーと接触するため、当該トナー粒子の静電特性が変化し、トナーの帯電特性の分布が広がり、感光体上カブリが起こると考えられる。
【００８１】
従って、特定のアゾ系鉄錯体化合物を用いることによって、トナーの帯電量を適正に制御し、過剰帯電を防ぐ効果で、混合工程における重合体微粒子の分散を促進し、重合体微粒子のトナーへの静電的固着によるトナー帯電性の変化を抑制する効果によっても、感光体上カブリの発生を低減しているものと考えられる。
【００８２】
本発明においては、無機微粉体はトナー粒子に対して、０．１〜３．０重量％の割合で含有されていることが必要である。より好ましい含有量としては、０．８〜２．５重量％である。含有量が０．１重量％未満では、トナーへの流動性付与、帯電補助の効果が十分ではなく、３．０重量％を超えるとトナーの定着性を阻害することとなる。また、含有量が０．８重量％以上である方がトナー表面の帯電均一性を得る上で有利であり、０．５重量％以下である方がトナーの低温定着化のためにはより望ましい。
【００８３】
無機微粉体は、トナー粒子の重量平均径の１／１０以下の粒径であることが好ましい。この無機微粉体の粒径とは、電子顕微鏡におけるトナー粒子の表面観察により求めたその平均粒径を意味する。無機微粉体としては、たとえば、以下のようなものが用いられる。金属酸化物（酸化アルミニウム，酸化チタン，チタン酸ストロンチウム，酸化セリウム，酸化マグネシウム，酸化クロム，酸化錫，酸化亜鉛，など）・窒化物（窒化ケイ素など）・炭化物（炭化ケイ素など）・金属塩（硫酸カルシウム，硫酸バリウム，炭酸カルシウムなど）・脂肪酸金属塩（ステアリン酸亜鉛，ステアリン酸カルシウムなど）・カーボンブラック・シリカなどである。
【００８４】
特に帯電安定性、現像性、流動性、保存性向上の為、少なくとも１種はシリカ、アルミナ、チタニア、あるいはその複酸化物の中から選ばれることが好ましい。例えば、かかるシリカは硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ、及びアルコキシド水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、またＮａ₂Ｏ、ＳＯ₃ ^2-等の製造残滓の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム、塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能でありそれらも包含する。
【００８５】
更に、無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与える。また、無機微粉体は、疎水化処理されていることが好ましく、シリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機硅素化合物、有機チタン化合物等の処理剤で、あるいは、種々の処理剤で併用して処理されていることも可能であり好ましい。特にシリカ、アルミナ、チタニア、あるいはその複酸化物を、シリコーンオイル、各種変性シリコーンオイル、各種カップリング剤で疎水化処理されたものが特に好ましい。
【００８６】
低消費量及び高転写率を達成するためには、無機微粉体は少なくともシリコーンオイルで処理されていることがさらに好ましい。
【００８７】
更には、トナー表面を無機微粉体で被覆することにより、感光体及び帯電部材等の接触部材からのストレスを緩和できるような構成をとることが望ましく、トナー表面の外添剤被覆率が５〜９９％、さらに好ましくは１０〜９９％であることが好ましい。また、さらにトナー粒子表面に無機微粉体を有することで、転写効率の向上及び文字やライン画像の転写中抜けが改善される。
【００８８】
トナー表面の外添剤被覆率は、日立製作所製ＦＥ−ＳＥＭ（Ｓ−８００）を用いトナー像を１００個無作為にサンプリングし、その画像情報はインターフェースを介してニコレ社製画像解析装置（Ｌｕｚｅｘ３）に導入し解析を行い算出した。
【００８９】
また、本発明中においては、重合体微粒子はトナー粒子に対して、０．０１〜３．０重量％の割合で含有されていることが必要である。含有量が０．０１重量％未満では、トナーへの無機微粉体の埋め込みを低減する効果が十分ではなく、３．０重量％を超えるとトナーの定着性を阻害することとなる。
【００９０】
重合体微粒子は、一次粒子の平均粒径が０．１〜３．０μｍであることが好ましい。また、トナー粒子の重量平均径の１／１０以下の粒径であることが好ましい。転写性および／またはクリーニング性向上のために一次粒径５０ｎｍ以上（好ましくは比表面積が３０ｍ²／ｇ未満）の球状に近い微粒子をさらに添加することも好ましい形態のひとつである。例えば球状ポリメチルシルセスキオキサン粒子、球状樹脂粒子等が好ましく用いられる。この重合体微粒子の粒径とは、電子顕微鏡におけるトナー粒子の表面観察により求めたその平均粒径を意味する。
【００９１】
また、重合体微粒子はトナー粒子と逆極性を有するものであることがより好ましい。逆極性を有する樹脂微粒子の方が同極性の重合体微粒子よりもトナー表面に良く付着し、均一な分散を長期間にわたり維持することが出来る。更には、重合体微粒子が凝集体として存在する場合、重合体微粒子がトナー粒子同極性であると、凝集物の大きさ、帯電量によってはトナー粒子の帯電性を阻害する、あるいは一成分系の現像ではトナー担持体上のトナーコート安定性を阻害することがあり、これらの意味からも重合体微粒子はトナー粒子と逆極性を有することが望ましい。このためにも、トナーを構成する重合体の主たるモノマーと樹脂微粒子を構成する主たるモノマーは異なることが望ましい。
【００９２】
重合体微粒子を得るためには従来公知の方法、すなわち乳化重合法やスプレードライ法を用いることが可能である。
【００９３】
好ましくは、スチレン、アクリル酸、メチルメタクリレート、ブチルアクリレート、２−エチルヘキシルアクリレートの如きモノマー成分を乳化重合法により単独重合もしくは共重合して得られる、ガラス転移点８０℃以上の樹脂微粒子が良好な効果を示す。
【００９４】
また、ジビニルベンゼンの如き架橋剤で架橋されていてもよく、比電気抵抗及びトリボ電荷量調整のために、樹脂粒子表面が感光体表面を傷つけない程度の金属、金属酸化物、顔料、界面活性剤等で処理されていてもよい。また、懸濁重合法によるトナー製法において、トナー粒子と同時に生成せしめても良い。また、当該樹脂微粒子は球形であることが望ましいが、当該樹脂微粒子が、感光体表面がシリカ微粉体で傷つくことを防止するのに有効に働き、且つ、クリーニングブレードで効果的に除去されるならば、適度に扁平していてもよく、また、その一部が扁平した形でトナー粒子表面に固着されていてもよい。
【００９５】
本発明のトナーには、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばテフロン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末、あるいは酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末などの研磨剤、ケーキング防止剤、あるいは例えば酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤として少量用いることもできる。
【００９６】
本発明において、トナー粒子の形状係数を示すＳＦ−１、ＳＦ−２とは、例えば日立製作所製ＦＥ−ＳＥＭ（Ｓ−８００）を用い１０００倍に拡大した２μｍ以上のトナー粒子像を１００個無作為にサンプリングし、その画像情報はインターフェースを介して、例えばニコレ社製画像解析装置（Ｌｕｚｅｘ ＩＩＩ）に導入し解析を行い下式より算出し得られた値を形状係数ＳＦ−１、ＳＦ−２と定義する。
【００９７】
【数１】

（式中、ＭＸＬＮＧは粒子の絶対最大長、ＰＥＲＩＭＥは粒子の周囲長、ＡＲＥＡは粒子の投影面積を示す）
【００９８】
尚、トナー粒子に重合体微粒子及び無機微粉体を外添した後に、上記の方法によりトナー粒子の形状係数の測定を行なう場合には、トナー粒子表面に付着している重合体微粒子や無機微粉体は、画像解析データには含まれないよう画像処理を行なう。
【００９９】
形状係数ＳＦ−１はトナー粒子の丸さの度合いを示し、形状係数ＳＦ−２はトナー粒子の凹凸の度合いを示している。
【０１００】
また、多数枚の画出しにおけるトナー担持体上のトナー融着や帯電部材表面の汚染を改善する観点から、ＳＦ−１の値が１００≦ＳＦ−１≦１２０であり、かつＳＦ−２の値が１００≦ＳＦ−２≦１１５であることが必要であり、より好ましくはＳＦ−１の値が１００≦ＳＦ−１≦１１５であり、かつＳＦ−２の値が１００≦ＳＦ−２≦１１３であるトナーが用いられることが、現像性を維持しながら転写性を向上させるために好ましい。
【０１０１】
ＳＦ−１が１２０よりも大きいと、重合体微粒子のトナーへの無機微粉体の埋め込みを低減する効果が有効に発現せず、その効果が十分な程度に重合体微粒子の添加量を増大させると、帯電量分布がブロードになりやすく、また現像同時回収プロセスでは、帯電部材のトナーによる汚染が促進され、帯電不良による画像不良を生じやすい。また、ＳＦ−２が１１５よりも大きいと、静電像保持体から転写材への転写時におけるトナー像の転写効率の低下し、さらに現像同時回収プロセスでは、帯電部材の汚染が促進され好ましくない。
【０１０２】
本発明で使用するアゾ系鉄錯体化合物は、下記式（１）で示す構造を有している。
【０１０３】
【化５】

［式中、Ｘ₁およびＸ₂は水素原子、低級アルキル基、低級アルコキシ基、ニトロ基及びハロゲン原子からなるグループから選択されるメンバーを表示し、Ｘ₁とＸ₂は同じ又は異なっており、ｍおよびｍ’は１〜３の整数を表示し、Ｒ₁およびＲ₃は水素原子、Ｃ₁〜Ｃ₁₈のアルキル基、Ｃ₂〜Ｃ₁₈のアルケニル基、スルホンアミド基、メシル基、スルホン酸基、カルボキシエステル基、ヒドロキシ基、Ｃ₁〜Ｃ₁₈のアルコキシ基、アセチルアミノ基、ベンゾイルアミノ基及びハロゲン原子からなるグループから選択されるメンバーを表示し、Ｒ₁とＲ₃は同じ又は異なっており、ｎおよびｎ’は１〜３の整数を表示し、Ｒ₂およびＲ₄は水素原子またはニトロ基を表示し、Ａ⁺はアンモニウムイオン、水素イオン、ナトリウムイオン、カリウムイオン及びそれらの混合イオンからなるグループから選択されるカチオンイオンを示す。］
【０１０４】
上記アゾ系鉄錯体化合物は負荷電制御剤としても用いられる。該化合物は公知の方法により合成できる。
【０１０５】
前記一般式のアゾ系鉄錯体化合物の代表的な具体例としては、次のような化合物が挙げられる。
【０１０６】
【化６】

【０１０７】
【化７】

【０１０８】
本発明においては、黒色着色剤として平均一次粒径が２５〜８０ｎｍであるカーボンブラックと、特定のアゾ系鉄錯体化合物を併用したトナーを用いることが好ましい。
【０１０９】
カーボンブラックの粒径に関しては、２５ｎｍよりも小さいと、本発明中のアゾ系鉄錯体化合物と併用した場合、一次粒径が微細なため、十分な分散が得られにくく、本発明の効果を得られない。更に、懸濁重合法にてトナーを作製する場合には、トナー粒度が粗粒化する傾向があり、使いこなすのが困難である。
【０１１０】
８０ｎｍよりも大きい場合には、良好に分散してもトナーとしての着色力の不足から、低濃度の画像しか得られない、或いはトナー消費量が増大する等の不都合が生ずる。
【０１１１】
カーボンブラックの粒径に関しては、粒径が２５〜５５ｎｍであることがより好ましい。本発明の特定のアゾ系鉄錯体化合物と併用した場合、カーボンブラックの粒径がこの範囲にあると、転写残トナーの帯電部材による帯電極性及び帯電量を制御がより確実に且つ均一になされ、トナーの帯電量の安定性及びトナー着色力の面でもより有利である。
【０１１２】
本発明におけるトナー中のカーボンブラックの平均一次粒径は、透過型電子顕微鏡で拡大した写真を撮影して測定することができる。
【０１１３】
本発明に用いられるカーボンブラックのＤＢＰ吸油量は４０〜１５０ｍｌ／１００ｇであることが望ましい。
【０１１４】
ＤＢＰ吸油量が４０ｍｌ／１００ｇ未満のストラクチャーの短いカーボンブラックではトナーの帯電量が低くなりすぎ易く、１５０ｍｌ／１００ｇを超えると強固な長ストラクチャーのためカーボンブラックの微細な分散が得られにくい。
【０１１５】
ＤＢＰ吸油量の測定は、ＡＳＴＭ法Ｄ２４１４−７９に準拠して行う。
【０１１６】
本発明に用いられるカーボンブラックは、窒素吸着比表面積が１００ｍ²／ｇ以下、揮発分が２％以下であることが望ましい。この本発明に係わるカーボンブラックは、通常トナーに多く用いられているカーボンブラックよりも比表面積が小さく、揮発分も少ない。
【０１１７】
比表面積が小さく、揮発分の少ないカーボンブラックは、重合阻害性の官能基が少ないことから、重合阻害性が低い利点があり、重合トナー中でのカーボンブラックの均一な分散にも有利である。
【０１１８】
カーボンブラックの窒素吸着比表面積に関しては、１００ｍ²／ｇよりも大きくなると重合阻害性を生じ易くなる。また、揮発分が２％を超えるカーボンブラックは、表面に重合阻害性の官能基が多数存在するため好ましくない。
【０１１９】
窒素吸着比表面積の測定は、ＡＳＴＭ法Ｄ３０３７−７８に準拠して行う。
【０１２０】
カーボンブラックの揮発分の測定は、「ＪＩＳ Ｋ ６２２１−１９８２」に準拠して行う。
【０１２１】
また、トナーを重合法で製造する場合、本発明に係わるカーボンブラックと前記アゾ系鉄錯体化合物を重合性単量体中に前分散する工程を行うことが望ましい。より高濃度でカーボンブラックを分散できるためせん断力がかかり易くなり、分散性向上の効果が大きくなる。
【０１２２】
図３に本発明に係わるカーボンブラック及びアゾ系鉄錯体化合物をスチレン中で分散したときの粘度変化を示す。図からも明らかなように、アゾ系鉄錯体化合物を添加することにより分散液の粘度が飛躍的に増大し、高せん断力でカーボンブラックが安定して分散されることを示している。
【０１２３】
また、図４において、粒径２５〜８０ｎｍのカーボンブラックにおいて、一定量のアゾ系鉄錯体化合物を添加しスチレン単量体中で分散したときのカーボンブラックの吸油量と分散液の粘度の関係を示す。この図から、４０ｍｌ／１００ｇ以上の高吸油量のカーボンブラックの方が分散液の粘度が高く、分散性が良いことが示されている。しかしながら、カーボンブラックの吸油量が１５０ｍｌ／１００ｇを超えると分散液の粘度が高くなりすぎ、重合時の造粒性を損ない易くなる。
【０１２４】
なお、本発明者らの検討によると、トナー粒子の重量に対する前記カーボンブラックの含有量Ａ［ｗｔ％］と、前記アゾ系鉄錯体化合物Ｂ［ｗｔ％］が、下記条件
２≦Ａ／Ｂ≦３５
を満たすことが好ましい。
【０１２５】
カーボンブラックの含有量に対してアゾ系鉄錯体化合物の含有量が少なすぎると、図３からも明らかなように粘度が上がらず、カーボンブラックが安定して分散しない。この場合、時間の経過とともにカーボンブラックが沈殿し、この分散液を用いてトナーを製造すると着色力が上がらない。カーボンブラックの含有量に対してアゾ系鉄錯体化合物の含有量が多すぎると、アゾ系鉄錯体が二次凝集を起こし、分散性が低下するとともに、重合阻害を起こし、トナー粒子を良好に製造することが困難となる。
【０１２６】
本発明において、トナー粒子中のカーボンブラックの含有量は、好ましくは０．１乃至３０重量％、より好ましくは１〜２０重量％であることが良い。カーボンブラックの含有量が０．１重量％未満では、トナーの着色力が低く、３０重量％を超える場合は、分散性が充分に均一にならない。
【０１２７】
また、本発明において、アゾ系鉄錯体化合物の含有量は、好ましくは０．０１乃至２０重量％、より好ましくは０．１乃至１０重量％であることが好ましい。アゾ系鉄錯体化合物の含有量が０．０１重量％未満では、分散液の粘度が上がりにくく、２０重量％を超す場合にも、やはり、分散液粘度が低下し、カーボンブラックの分散性向上の効果が十分でない。
【０１２８】
本発明においては、前記トナーを重合法にて形成する際、使用する重合性単量体中に前記カーボンブラックと前記アゾ系鉄錯体化合物を前分散させることで、カーボンブラックの分散性向上の効果が著しい。これはより高濃度で分散させるために分散液が高粘度となり、高シェアで分散が行われるためである。
【０１２９】
上述したように、本発明者らは、特定の吸油量範囲で適正なストラクチャーを有し、比表面積が小さく、揮発分も少ないカーボンブラックを特定のアゾ系鉄錯体化合物と併用することで、転写トナーの帯電部材通過時の帯電制御特性が、より改善されるトナーを得ることを見い出した。
【０１３０】
このようにして得られたトナーを適用することで、転写残トナー中の過剰な帯電量のトナー粒子や逆極性の過剰な帯電量の粒子の存在割合が少なくなり、クリーニング性が向上する。また、より高速なプロセススピードの系の現像同時クリーニング、クリーナレス画像形成方法においても、感光体帯電部材を通過する際、トナーがより確実に且つ均一に帯電極性制御されることで、現像での安定した回収性を示し、転写残トナーとして現像で回収された後現像にその一部が再利用される際にも、現像特性に悪影響を及ぼすことなく、高品質な画像を安定して実現することができる。
【０１３１】
更に高画質化のためより微小な潜像ドットを忠実に現像するために、トナー粒子は重量平均径が３μｍ〜９μｍであることが好ましい。重量平均径が３μｍ未満のトナー粒子においては、転写効率の低下から感光体や中間転写体上に転写残のトナーが多く、さらに、カブリ・転写不良に基づく画像の不均一ムラの原因となりやすく、本発明で使用するトナーには好ましくない。また、トナー粒子の重量平均径が９μｍを超える場合には、文字やライン画像に飛び散りが生じやすい。
【０１３２】
トナーの平均粒径及び粒度分布はコールターカウンターＴＡ−ＩＩ型あるいはコールターマルチサイザー（コールター社製）等を用い、個数分布、体積分布を出力するインターフェイス（日科機製）及びＰＣ９８０１パーソナルコンピューター（ＮＥＣ製）を接続し、電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。たとえば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルフォン酸塩）を０．１〜５ｍｌ加え、更に測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行ない前記コールターカウンターＴＡ−ＩＩ型によりアパーチャーとして１００μｍアパーチャーを用いて、２μｍ以上のトナーの体積、個数を測定して体積分布と個数分布とを算出した。それから、本発明に係わる体積分布から求めた体積基準の重量平均粒径（Ｄ４）、個数分布から求めた個数基準の個数平均粒径（Ｄｌ）を求めた。
【０１３３】
トナーの定着性及び耐オフセット性を向上させるために、離型剤をトナー粒子に添加することが好ましい。離型剤としては、ＡＳＴＭ Ｄ３４１８−８に準拠し測定されたＤＳＣ曲線における主体吸熱極大ピーク値（融点）が、３０〜１２０℃（より好ましくは４０〜９０℃）の範囲にある化合物が好ましい。離型剤の極大ピーク値（融点）が３０℃未満であると離型剤の自己凝集力が弱くなり、結果として耐高温オフセット性が弱くなり好ましくない。一方、極大ピーク値が１２０℃を超えると定着温度が高くなり、定着画像表面を適度に平滑化させることが困難となり混色性低下の点から好ましくない。更に直接重合方法によりトナー粒子を得る場合においては、水系媒体中で造粒・重合を行うため、吸熱極大ピーク値の温度が高いと主に造粒中に離型剤が析出してくるので好ましくない。
【０１３４】
離型剤の極大ピーク値の温度（融点）の測定には、例えばパーキンエルマー社製ＤＳＣ−７を用いる。装置検出部の温度補正はインジウムと亜鉛の融点を用い、熱量の補正についてはインジウムの融解熱を用いる。サンプルはアルミニウム製パンを用い対照用に空パンをセットし、温度２０℃から１８０℃まで昇温速度１０℃／ｍｉｎで測定を行う。
【０１３５】
離型剤としては、パラフィンワックス，ポリオレフィンワックス，フィッシャートロピッシュワックスの如きポリメチレンワックス，アミドワックス，高級脂肪酸，高級脂肪酸金属塩，長鎖アルキルアルコール，エステルワックス及びこれらの誘導体（例えばこれらのグラフト化合物又はブロック化合物等）が挙げられる。
【０１３６】
また、離型剤はトナー中へ２〜３０重量％添加することが好ましい。仮に２重量％未満の添加では定着性の改善が不十分であり、また３０重量％を超える場合は、トナーの流動性・帯電性を阻害することが多く、重合法による製造においても造粒時にトナー粒子同士の合一が起きやすく、粒度分布の広いものが生成しやすく、本発明には不適当であった。
【０１３７】
本発明においては、トナーにコア／シェル構造をもたせ、シェル部分を重合により合成された重合体によって形成され、コア部分を離型剤としてのワックスで構成するようなトナーを本発明の画像形成方法に用いることにより、トナー粒子の劣化や画像形成装置への汚染を防止することが出来るので良好な帯電性が維持され、ドット潜像の再現に優れたトナー画像を長期にわたって形成し得ることが可能となる。また、加熱加圧定着時にはワックスが効率良く作用する為、低温定着性と耐高温オフセット性とを向上させることができるから好ましい。
【０１３８】
本発明において、コア／シェル構造を有するトナーとは、離型剤としてのワックスによるコア部の表面を重合性単量体の重合によって合成された重合体によって形成されるシェル部が被覆している形態のトナーを意味する。
【０１３９】
本発明において、トナーのコア／シェル構造は、トナー粒子の断面層観察により確認することが出来る。
【０１４０】
トナー粒子の断層面を観察する具体的方法としては、常温硬化性のエポキシ樹脂中にトナー粒子を十分分散させた後、４０℃の雰囲気中で２日間硬化させ、得られた硬化物を四三酸化ルテニウム、必要により四三酸化オスミウムを併用し染色を施した後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出し、透過電子顕微鏡（ＴＥＭ）を用いトナー粒子の断層形態を観察する。ワックスと外殻を構成する樹脂との若干の結晶化度の違いを利用して材料間のコントラストを付けるため四三酸化ルテニウム染色法を用いることが好ましい。
【０１４１】
本発明において、離型剤のトナー粒子における含有量は、好ましくは２〜３０重量％、より好ましくは２〜２５重量％であることが好ましい。
【０１４２】
離型剤の含有量が２重量％未満では定着性の改善が不十分であり、３０重量％を超える場合は、重合法による製造においても造粒時にトナー粒子同士の合一が起きやすく、粒度分布の広いものが生成しやすく、本発明には不適当であった。
【０１４３】
本発明においては、コア／シェル構造を有するトナーを製造する場合、シェル部が離型剤としてのワックスによるコア部を内包化せしめるためシェル部を構成する樹脂に更に極性樹脂を添加せしめることが特に好ましい。
【０１４４】
本発明に用いられる極性樹脂としては、スチレンと（メタ）アクリル酸の共重合体，マレイン酸共重合体，飽和ポリエステル樹脂，エポキシ樹脂が好ましく用いられる。
【０１４５】
トナー粒子中極性樹脂の含有量は、好ましくは１〜２０重量％、より好ましくは２〜１６重量％（トナー粒子の重量基準）であることが良い。
【０１４６】
極性樹脂の含有量が１重量％未満の場合には、添加効果が十分に発現されず、また、２０重量％を超える場合にはトナーの帯電特性に影響を及ぼすことが多く、特に高温高湿環境下でのトナーの帯電性の低下を招き易く好ましくない。
【０１４７】
本発明においては、トナーの表面にさらに最外殻樹脂層を設けても良い。
【０１４８】
該最外殻樹脂層のガラス転移温度は、耐ブロッキング性のさらなる向上のため外殻樹脂層のガラス転移温度以上に設計されること、さらに定着性を損なわない程度に架橋されていることが好ましい。この最外殻樹脂層には帯電性向上のため極性樹脂や荷電制御剤が含有されていることが好ましい。
【０１４９】
該最外殻層を設ける方法としては、特に限定されるものではないが例えば以下のような方法が挙げられる。
【０１５０】
１．重合反応後半、または終了後、反応系中に必要に応じて、極性樹脂、荷電制御剤、架橋剤を溶解、分散したモノマーを添加し重合粒子に吸着させ、重合開始剤を添加し重合を行う方法。
【０１５１】
２．必要に応じて、極性樹脂、荷電制御剤、架橋剤を含有したモノマーからなる乳化重合粒子またはソープフリー重合粒子を反応系中に添加し、重合粒子表面に凝集、必要に応じて熱により固着させる方法。
【０１５２】
３．必要に応じて、極性樹脂、荷電制御剤、架橋剤を含有したモノマーからなる乳化重合粒子またはソープフリー重合粒子を乾式で機械的にトナー粒子表面に固着させる方法。
【０１５３】
本発明において、着色剤及び重合性単量体と共に離型剤としてのワックス及び極性樹脂を含有する単量体組成物を水系媒体中で重合することによりトナー粒子を製造する重合法によって、ワックス及び極性樹脂を含有するトナー粒子を製造する場合には、製造されたトナー粒子はワックスによるコア部と重合性単量体の重合により合成された重合体及び極性樹脂によって構成されるシェル部とを有するコア／シェル構造を有し、さらにシェル部の最外殻樹脂層に極性樹脂が位置する形態となる。
【０１５４】
したがって、このような形態のトナー粒子の場合には、着色剤として用いるカーボンブラックの表面には、極性基が存在しているため、カーボンブラックは、非極性のワックス中には入り込まず、シェル部に位置することになり、トナー粒子中に均一にカーボンブラックが分散している形態のトナー粒子に比べて着色力が低下し易い傾向にあり、またシェル部の最外殻層には極性樹脂が位置するため、トナー粒子の表面部に位置するカーボンブラックの割合が少なくなることから、極性樹脂を含有しないトナー粒子に比べて、トナーの摩擦帯電性が低い傾向にある。
【０１５５】
しかしながら、本発明においては、トナー粒子は、上述の如く、カーボンブラック及び特定のアゾ系鉄化合物を含有していることから、アゾ系鉄化合物によるカーボンブラックの分散性向上効果によりトナーの着色力の低下を抑制し、かつカーボンブラックの分散性向上効果とアゾ系鉄化合物の高い荷電制御効果によりトナーの摩擦帯電性の低下を抑圧することが可能である。
【０１５６】
本発明の一成分接触現像方式の画像形成方法においては、現像時にトナー担持体上のトナーが像担持体の表面に接触することから、トナーの耐久性やトナー担持体の表面及び像担持体の表面に対するトナーの耐融着性を有していることが好ましい。
【０１５７】
従って、一成分非接触現像方式やトナー及びキャリアを有する二成分現像方式に用いるトナーに比べて、一成分接触現像方式に用いるトナーは、より高い機械的特性を有することが要求される。
【０１５８】
本発明に用いられるトナーの結着樹脂としては、一般的に用いられているスチレン−（メタ）アクリル共重合体，ポリエステル樹脂，エポキシ樹脂，スチレン−ブタジエン共重合体を利用することが出来る。重合法によってトナー粒子を得る方法においては、それらの単量体が好ましく用いられる。具体的には、スチレン，ｏ（ｍ−、ｐ−）−メチルスチレン，ｍ（ｐ−）−エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル，（メタ）アクリル酸エチル，（メタ）アクリル酸プロピル，（メタ）アクリル酸ブチル，（メタ）アクリル酸オクチル，（メタ）アクリル酸ドデシル，（メタ）アクリル酸ステアリル，（メタ）アクリル酸ベヘニル，（メタ）アクリル酸２−エチルヘキシル，（メタ）アクリル酸ジメチルアミノエチル，（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体；ブタジエン，イソプレン，シクロヘキセン，（メタ）アクリロニトリル，アクリル酸アミドの如きエン系単量体が好ましく用いられる。これらの単量体は、ポリマーハンドブック第２版−Ｐｌ３９〜１９２（ＪｏｈｎＷｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を単独で又は適宜混合し用いられる。理論ガラス転移温度が４０℃未満の場合には、トナーの保存安定性や現像剤の耐久安定性の面から問題が生じ、一方７５℃を超える場合は定着点の上昇をもたらす。
【０１５９】
結着樹脂の分子量は、ＧＰＣ（ゲルパーミエーションクロマトグラフィー）により測定される。具体的なＧＰＣの測定方法としては、予めトナーをソックスレー抽出器を用いトルエン溶剤で２０時間抽出を行った後、ロータリーエバポレーターでトルエンを留去せしめ、更に離型剤は溶解するが結着樹脂は溶解し得ない有機溶剤例えばクロロホルム等を加え十分洗浄を行った後、ＴＨＦ（テトラヒドロフラン）に可溶した溶液をポア径が０．３μｍの耐溶剤性メンブランフィルターでろ過したサンプルをウォーターズ社製１５０Ｃを用い、カラム構成は昭和電工製Ａ−８０１、８０２、８０３、８０４、８０５、８０６、８０７を連結し標準ポリスチレン樹脂の検量線を用い分子量分布を測定し得る。得られた樹脂成分の数平均分子量（Ｍｎ）は、５０００〜１００００００で有り、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）の比（Ｍｗ／Ｍｎ）は、２〜１００を示す結着樹脂が本発明には好ましい。
【０１６０】
本発明に用いられるアゾ系鉄錯体化合物は、荷電制御剤としての機能も有しているが、更に別の荷電制御剤を併用してもよい。別の荷電制御剤としては、公知のものが利用できるが、帯電スピードが速く且つ一定の帯電量を安定して維持できる荷電制御剤が好ましい。更に本発明において重合法でトナー粒子を製造する場合には、重合阻害性が無く水系への可溶化物の無い荷電制御剤が特に好ましい。
【０１６１】
別の荷電制御剤の具体的化合物としては、ネガ系としてサリチル酸、ナフトエ酸、ダイカルボン酸またはその誘導体の金属化合物、アゾ顔料またはその誘導体の金属化合物、スルホン酸、カルボン酸を側鎖に持つ高分子型化合物、ホウ素化合物、尿素化合物、ケイ素化合物、カリークスアレーン等が利用できる。ポジ系としてニグロシン、トリフェニルメタン系化合物、四級アンモニウム塩、該四級アンモニウム塩を側鎖に有する高分子型化合物、グアニジン化合物、イミダゾール化合物等が好ましく用いられる。別の荷電制御剤は結着樹脂１００重量部に対し０．２〜１０重量部が好ましい。しかしながら、本発明において別の荷電制御剤の添加は必須ではなく、非磁性一成分ブレードコーティング現像方法を用いた場合においてもブレード部材やスリーブ部材との摩擦帯電を積極的に利用することでトナー中に必ずしも別の荷電制御剤を含む必要はない。
【０１６２】
本発明で重合法でトナー粒子を製造する場合には、重合開始剤として、例えば、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシドの如き過酸化物系重合開始剤が用いられる。
【０１６３】
該重合開始剤の添加量は、目的とする重合度により変化するが一般的には単量体に対し０．５〜２０重量％添加され用いられる。開始剤の種類は、重合方法により若干異なるが、十時間半減期温度を参考に、単独又は混合し利用される。
【０１６４】
重合度を制御するため公知の架橋剤・連鎖移動剤・重合禁止剤等を更に添加し用いることも可能である。
【０１６５】
本発明に係るトナー製造方法として懸濁重合を利用する場合には、用いる分散剤として例えば無機系酸化物として、リン酸三カルシウム，リン酸マグネシウム，リン酸アルミニウム，リン酸亜鉛，炭酸カルシウム，炭酸マグネシウム，水酸化カルシウム，水酸化マグネシウム，水酸化アルミニウム，メタケイ酸カルシウム，硫酸カルシウム，硫酸バリウム，ベントナイト，シリカ，アルミナ，磁性体，フェライト等が挙げられる。有機系化合物としは例えばポリビニルアルコール，ゼラチン，メチルセルロース，メチルヒドロキシプロピルセルロース，エチルセルロース，カルボキシメチルセルロースのナトリウム塩，デンプン等が水相に分散させて使用される。これら分散剤は、重合性単量体１００重量部に対して０．２〜１０．０重量部使用することが好ましい。
【０１６６】
これら分散剤は、市販のものをそのまま用いても良いが、細かい均一な粒度を有す分散粒子を得るために、分散媒中にて高速撹拌下にて該無機化合物を生成させて用いることも出来る。例えば、リン酸三カルシウムの場合、高速撹拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合することで懸濁重合方法に好ましい分散剤を得ることが出来る。またこれら分散剤の微細化のため０．００１〜０．１重量部の界面活性剤を併用しても良い。具体的には市販のノニオン，アニオン，カチオン型の界面活性剤が利用でき，例えばドデシル硫酸ナトリウム，テトラデシル硫酸ナトリウム，ペンタデシル硫酸ナトリウム，オクチル硫酸ナトリウム，オレイン酸ナトリウム，ラウリル酸ナトリウム，ステアリン酸カリウム，オレイン酸カルシウム等が好ましく用いられる。
【０１６７】
本発明に係るトナー製造方法に重合法を用いる場合においては、以下の如き製造方法によって具体的にトナーを製造することが可能である。単量体中に低軟化点物質からなる離型剤，着色剤，荷電制御剤，重合開始剤その他の添加剤を加え、ホモジナイザー・超音波分散機等によって均一に溶解又は分散せしめた単量体組成物を、分散安定剤を含有する水相中に通常の撹拌機またはホモミキサー，ホモジナイザー等により分散せしめる。好ましくは単量体組成物からなる液滴が所望のトナー粒子のサイズを有するように撹拌速度・時間を調整し、造粒する。その後は分散安定剤の作用により、粒子状態が維持され、且つ粒子の沈降が防止される程度の撹拌を行えば良い。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行う。また、重合反応後半に昇温しても良く、更に、本発明の画像形成方法における耐久特性向上の目的で、未反応の重合性単量体、副生成物等を除去するために反応後半、又は、反応終了後に一部水系媒体を留去しても良い。反応終了後、生成したトナー粒子を洗浄・ろ過により回収し、乾燥する。懸濁重合法においては、通常単量体系１００重量部にたいして水３００〜３０００重量部を分散媒として使用するのが好ましい。
【０１６８】
本発明中のトナーを作製するには、公知の方法が用いられるが、例えば、本発明のトナーを製造する方法としては、樹脂，アゾ系鉄錯体化合物，カーボンブラック，離型剤等を加圧ニーダーやエクストルーダー又はメディア分散機を用い均一に分散せしめた後、機械的又はジェット気流下でターゲットに衝突させ、所望のトナー粒径に微粉砕化せしめた後、更に分級工程を経て粒度分布をシャープ化せしめトナー化する所謂粉砕方法によるトナーの製造方法、特公昭５６−１３９４５号公報に記載のディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報，特開昭５９−５３８５６号公報，特開昭５９−６１８４２号公報に述ベられている懸濁重合方法を用いて直接トナーを生成する方法、重合性単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合方法、又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合方法に代表される乳化重合方法等を用いトナーを製造することが可能である。
【０１６９】
また、本発明は、感光体表面が有機化合物である様な画像形成装置において特に有効に用いられる。即ち、有機化合物が感光体の表面層を形成している場合には、無機材料を用いた他の感光体よりもトナー粒子に含まれる結着樹脂との接着性に優れ、転写性がより低下する傾向にあるためである。
【０１７０】
また、本発明に係わる感光体の表面物質としては、たとえばシリコーン樹脂、塩化ビニリデン、エチレン−塩化ビニル、スチレン−アクリロニトリル、スチレン−メチルメタクリレート、スチレン、ポリエチレンテレフタレートおよびポリカーボネート等が挙げられるが、これらに限定されることはなく他のモノマーあるいは前述の結着樹脂間での共重合体およびブレンド体等も使用することができる。
【０１７１】
また、本発明は、感光体表面に離型性を付与することが好ましく、感光体表面の水に対する接触角は８５度以上であることが好ましい。より好ましくは感光体表面の水に対する接触角は９０度以上である。感光体表面が高い接触角を有することは、感光体表面が高い離型性有することを示し、この効果により、転写残余のトナー量を著しく減少させることができ、クリーニング工程での負荷を大幅に低減し、本発明中のトナーを用いた際、クリーニング不良の発生をより確実に防止することができる。
【０１７２】
また、現像同時回収プロセスにおいても、転写残余のトナー量を著しく減少させることが出来、転写残トナーのによる遮光がほとんどなくネガゴースト画像を本質的に防止できると共に現像時に転写残トナーの現像域での回収効率も向上し、ポシゴースト画像を防止する。
【０１７３】
ここで、ゴースト画像の発生メカニズムを説明する。
【０１７４】
転写残トナーによる遮光が特に問題となるのは、一枚の転写材に対し感光体表面が繰り返し使用される場合、つまり感光体一周分の長さが転写材の進行方向長さよりも短い場合、転写残トナーが感光体上に存在する状態で帯電、露光及び現像をしなければならないため、転写残トナーの存在する感光体表面部での電位が充分落ちきらず現像コントラストが不十分になるため反転現像については周囲よりも濃度が低い、ネガゴーストとして画像上に現れる。
【０１７５】
一方、現像時に転写残トナーのクリーニング効果が不十分であれば、転写残トナーの存在する感光体表面上に、トナーが現像されるため周囲よりも濃度が高く、ポシゴーストが発生する。
【０１７６】
本発明の構成にて、上記説明のゴースト画像を本質的に防止できる。
【０１７７】
感光体表面に有機化合物を用いる場合としては、例えば、セレン、アモルファスシリコンなどの無機感光体の上に、樹脂を主体とした保護膜を設ける場合、又は機能分離型有機感光体の電荷輸送層として、電荷輸送材と樹脂を有する表面層をもつ場合、さらにその上に上記のような保護層を設ける場合等がある。このような表面層に離型性を付与する手段としては、
▲１▼膜を構成する樹脂自体に表面エネルギーの低いものを用いる、
▲２▼撥水、親油性を付与するような添加剤を加える、
▲３▼高い離型性を有する材料を粉体状にして分散する、
などが挙げられる。▲１▼としては、樹脂の構造中にフッ素含有基、シリコーン含有基等を導入することにより達成する。▲２▼としては、界面活性剤等を添加剤として添加すればよい。▲３▼としては、フッ素原子を含む化合物、すなわちポリ４フッ化エチレン、ポリフッ化ビニリデン、フッ化カーボンの如きフッ素原子を含む化合物を用いることが挙げられる。
【０１７８】
これらの手段によって感光体表面の水に対する接触角を８５度以上とすることができる。８５度未満では耐久によるトナーおよびトナー担持体の劣化が生じやすい。
【０１７９】
この中でも特にポリ４フッ化エチレン、ポリフッ化ビニリデンの如き含フッ素樹脂が好適である。本発明においては、▲３▼の含フッ素樹脂を離型性粉体として用いた場合には最表面層への分散が好適である。
【０１８０】
これらの粉体を表面に含有させるためには、バインダー樹脂中に該粉体を分散させた層を感光体最表面に設けるか、あるいは、元々樹脂を主体として構成されている有機感光体であれば、新たに表面層を設けなくても、最表面層に該粉体を分散させれば良い。
【０１８１】
該粉体の表面層への添加量は、表面層総重量に対して、１〜６０重量％、さらには２〜５０重量％が好ましい。１重量％より少ないと転写残余のトナーが充分に減少せず、転写残トナーのクリーニング効率も充分でなく、ゴースト防止効果が不十分であり、６０重量％を超えると膜の強度が低下したり、感光体への入射光量が著しく低下したりするため、好ましくない。また、該粉体の粒径については、画質の面から、１μｍ以下、好ましくは０．５μｍ以下が望ましい。１μｍより大きいと入射光の散乱によりラインの切れが悪くなり実用に耐えない。
【０１８２】
保護層の樹脂としては、ポリエステル・ポリカーボネート・アクリル樹脂・エポキシ樹脂・フェノール樹脂、あるいはこれらの樹脂の硬化剤等が単独あるいは２種以上組み合わされて用いられる。
【０１８３】
また、保護層の樹脂中に導電性微粒子を分散してもよい。導電性微粒子の例としては、金属・金属酸化物等が挙げられ、好ましくは、酸化亜鉛・酸化チタン・酸化スズ・酸化アンチモン・酸化インジウム・酸化ビスマス・酸化スズ被膜酸化チタン・スズ被膜酸化インジウム・アンチモン被膜酸化スズ・酸化ジルコニウム等の超微粒子がある。これらは単独で用いても２種以上を混合して用いても良い。一般的に保護層に粒子を分散させる場合、分散粒子による入射光の散乱を防ぐために入射光の波長よりも粒子の粒径の方が小さいことが必要であり、本発明における保護層に分散される導電性、絶縁性粒子の粒径としては０．５μｍ以下であることが好ましい。また、保護層中での含有量は、保護層総重量に対して２〜９０重量％が好ましく、５〜８０重量％がより好ましい。保護層の膜厚は、０．１〜１０μｍが好ましく、１〜７μｍがより好ましい。
【０１８４】
表面層の塗工は、樹脂分散液をスプレーコーティング、ビームコーティングあるいは浸透（ディッピング）コーティングすることによって行うことができる。
【０１８５】
本発明に用いられる好ましい現像工程の条件としては、トナー担持体上のトナー層と感光体表面が接触しているということである。
【０１８６】
一成分現像剤の場合、トナー担持体として弾性ローラーを用い、弾性ローラー表面にトナーをコーティングして形成したトナー層を感光体表面と接触させる方法も用いられる。このとき、トナーの磁性、非磁性は問わず、ただ、トナー層と感光体表面が接触していることが重要となる。また、トナー担持体は実質的に感光体表面と接触しているが、これは、トナー担持体からトナー層を除いたときに該トナー担持体が感光体と接触しているということを意味する。このとき、トナー層を介して、感光体と感光体表面に対向する弾性ローラー間に働く電界によってエッジ効果のない画像を得るためには、弾性ローラー表面あるいは、表面近傍が電位をもち、感光体表面とトナー担持表面との間で電界を有する必要性がある。このため、弾性ローラーの弾性ゴムが中抵抗領域に抵抗制御されて感光体表面との導通を防ぎつつ電界を保つか、または導電性ローラーの表面層に薄層の絶縁層を設ける方法も利用できる。さらには、導電性ローラ上に感光体表面に対向する側を絶縁性物質により被覆した導電性樹脂スリーブあるいは、絶縁性スリーブで感光体に対向しない側に導電層を設けた構成も可能である。また、トナー担持体として剛体ローラを用い、感光体をベルトのごときフレキシブルなものとした構成も可能である。トナー担持体としての現像ローラの電気抵抗としては１０²〜１０⁹Ω・ｃｍの範囲が好ましい。
【０１８７】
一成分接触現像法を用いた場合そのトナーを担持する現像ローラー表面と感光体の周速同方向に回転していてもよいし、逆方向に回転していてもよい。その回転が同方向である場合感光体の周速に対して、周速比で１００％よりも速いことが望ましい。１００％以下であると、画像品質が悪い。周速比が高まれば高まるほど、現像部位に供給されるトナーの量は多く、潜像に対しトナーの脱着頻度が多くなり、不要な部分は掻き落とされ必要な部分には付与されるという繰り返しにより、潜像に忠実な画像が得られる。具体的には、トナー担持体面の移動速度が感光体面の移動速度に対し、１．０５〜３．０倍の速度であることが好ましい。
【０１８８】
本発明に用いられるクリーニング部材としては、ブレード、ローラー、ファーブラシ、磁気ブラシ等を用いることが出来る。また、これらのクリーニング部材の２種類以上を組み合わせて使用してもよい。
【０１８９】
一成分接触現像による画像形成方法においては、感光体上の現像トナーの帯電量を適正に制御することで、転写残トナーの過剰帯電によるクリーニング性の低下を防止し得る。
【０１９０】
すなわち、転写残トナーの過剰に帯電してしまうと、感光体への転写残余のトナーの付着力が高いためにクリーニング性が低下し易い。特に、懸濁重合法の如き重合法によって作成されたトナーのように、トナー粒子の形状が球形に近い場合、クリーニング工程でのスクレイプ性の低下、クリーニング部材からのすり抜け易さ等の点でクリーニングに不利であり、転写残トナーの過剰帯電はクリーニング性を著しく低下させる。
【０１９１】
転写残余のトナーの帯電は、転写バイアス条件、転写材の抵抗等によっても大きく変化する。転写バイアスは一般にトナーの帯電極性とは逆極性の電圧が印加されるが、現像が正現像（トナー帯電極性と感光体帯電極性が逆）である場合、転写材が厚紙、ＯＨＴフィルムのように高抵抗なものであると、高い帯電を持ったトナー粒子が感光体との強い付着力によって転写されることなく、そのままの帯電でクリーニング工程へと進みクリーニングしきれなくなり易い。
【０１９２】
したがって、トナーとしては、感光体上の現像トナーが帯電量を適正に制御され、元々高帯電量のトナーが感光体に現像されていないことが望ましい。
【０１９３】
さらには、接触現像法では、トナー層と感光体表面が接触しているために、感光体との摩擦によるトナーに対する帯電付与が生じ、感光体との摩擦による帯電が、現像トナーの帯電に少なからず影響することが判明した。本発明者らの検討によれば、トナーの画像解析装置で測定した形状係数ＳＦ−１の値が１００＜ＳＦ−１≦１６０であり、かつＳＦ−２の値が１００＜ＳＦ−２≦１４０である場合には、感光体との摩擦によるトナーに対する帯電付与が均一なものとなり、高帯電量のトナーが感光体に現像されにくいのに対して、ＳＦ−１の値がＳＦ−１＞１６０であるか、あるいはＳＦ−２の値がＳＦ−２＞１４０である場合には、感光体との摩擦によるトナーに対する帯電付与が不均一なものとなり、トナー帯電のばらつきが大きくなり、高帯電量のトナーが生成し、一部が感光体にまで現像されることが判明した。
【０１９４】
更に、本発明者らの検討によれば、本発明中のトナーに添加される重合体微粒子が帯電性を有する場合、トナー形状による接触現像法における感光体表面との摩擦によるトナーに対する帯電付与のされ方が、より大きく影響されることが判明した。
【０１９５】
すなわち、重合体微粒子の帯電性は、トナー粒子と逆極性であることが重合体微粒子の付着性の点で有利であるが、重合体微粒子がトナー粒子から遊離して存在する場合、もしくは、現像工程から転写工程終了までの間に遊離する場合、重合体微粒子が非常に高い帯電量で感光体表面に付着し、クリーニング性を著しく低下させる原因となる。
【０１９６】
また重合体微粒子がトナーと同極性の帯電性を有する場合は、遊離重合体微粒子自体が粒径が小さいために大きな比電荷をもち、トナー粒子の均一な帯電を阻害し、現像性・転写性を大幅に低下させる。このような重合体微粒子のトナー粒子からの遊離が、感光体表面とトナー層とが摺擦されることにより、大幅に起こり易くなり、重合体微粒子のトナー粒子からの遊離と、トナー形状とが密接に関連していることが、本発明者らの検討により判明した。
【０１９７】
トナーの形状係数ＳＦ−１の値が１００≦ＳＦ−１≦１２０であり、かつ、ＳＦ−２の値が１００≦ＳＦ−２≦１１５である場合、重合体微粒子のトナー粒子からの遊離を抑制しつつ、重合体微粒子のトナーへの無機微粉体の埋め込みを低減する効果が有効に発現し、かつ、感光体との摺擦によるトナーへの帯電付与が均一となり、長期にわたり安定した帯電性を示すトナーが得られる。
【０１９８】
トナー粒子表面に凹凸がある場合、凹部は、重合体微粒子の遊離は起こりにくいが、トナー粒子への無機微粉体への埋め込みを低減する効果を鑑みて、接触機会・帯電機会のより小さなトナー粒子凹部の無機微粒子の埋め込みを低減してもトナー粒子としての帯電性・流動性を維持する効果は小さい。
【０１９９】
トナー粒子間、帯電付与部材、トナー担持体、トナー層厚規制部材、感光体等との接触機会のより大きなトナー粒子凸部でも重合体微粒子の付着性・遊離のしやすさがトナー全体としての帯電性に大きく影響する。
【０２００】
トナー粒子の凸部がより滑らかである方が、重合体微粒子のトナー粒子からの遊離は起こりにくく、トナーの形状係数ＳＦ−１が１２０よりも大きい場合、もしくはＳＦ−２が１１５よりも大きい場合には、トナー粒子が感光体との摺擦による大きなストレスを余分に受ける接触現像法では、トナー粒子凸部での重合体微粒子の遊離が起こり易くなり、安定したトナー帯電性が得られにくい。
【０２０１】
現像同時クリーニングプロセスにおいても、重合体微粒子のトナー粒子からの遊離は、帯電部材の重合体微粒子による汚染を招き、帯電部材による感光体の均一帯電を著しく阻害する、あるいは、現像性を低下させるという悪影響を及ぼす。
【０２０２】
従って、現像同時クリーニングプロセスにおいても、トナーの形状係数はＳＦ−１は１００≦ＳＦ−１≦１２０であり、かつＳＦ−２は１００≦ＳＦ−２≦１１５であることが必要である。
【０２０３】
また、高帯電量のトナーが感光体に現像されないためには、トナーへの帯電付与或いはトナーの帯電性を押さえる必要があるが、トナーの帯電が十分でないとカブリ、トナー飛散、転写性の低下等の弊害を生じ易くなる。本発明のトナーを用いることで、過剰な高帯電トナー粒子の生成を抑制し、適正な帯電量をトナーに持たせることが可能となった。これにより現像工程においても耐久性に優れた安定した性能を示す。
【０２０４】
また、現像が反転現像（トナー帯電極性と感光体帯電極性が同極性）の場合、転写材が薄紙のように電界を通し易いものの場合、転写バイアスによって逆極性に強く帯電されるトナーができ、やはり感光体との強い付着力をもちクリーニングしきれなくなり易い。
【０２０５】
これに対し、本発明のトナーを用いることで、過剰に逆極性に帯電したトナー粒子の生成を抑制すること及び転写バイアスによるトナー帯電の制御が可能となった。
【０２０６】
これらの理由については必ずしも明らかではないが、本発明中のトナーに用いられる重合体微粒子と特定のアゾ系鉄錯体化合物が、トナーが異常に高帯電量となる（いわゆるチャージアップ現象）ことを防止する効果で、転写工程でトナー極性と逆電界を印加されても、過剰な逆電荷をトナーが保持しにくくしていること、及び重合体微粒子との併用により耐久によってもトナー表面に安定に存在する無機微粉体の効果、更には、特定の形状を有するトナーを用いることで、感光体との摩擦帯電によるトナー帯電のばらつきを抑制した効果によると考えている。
【０２０７】
本発明に用いられる好ましい画像形成方法の一つとしては、転写工程の後感光体上に残存するトナーを現像工程において回収する工程を有することである。
【０２０８】
先ず、この現像同時クリーニング方法あるいはクリーナレス画像形成方法の原理を説明する。
【０２０９】
その原理は、電子写真各工程における感光体上のトナーの帯電極性及び帯電量を制御することと反転現像方法を用いていることにある。
【０２１０】
例を挙げて説明すると、マイナス帯電性の感光体及びマイナス帯電性のトナーを用いた場合、その転写工程において、プラス極性の転写部材によって可視化された像を転写材に転写することになるが、転写材の種類（厚み、抵抗、誘電率等の違い）と画像面積等の関係により、転写残余のトナーの帯電極性がプラスからマイナスまで変動する。しかし、マイナス帯電性の感光体を帯電する際のマイナス極性の帯電部材により、感光体表面と共に転写残余のトナーまでもが、転写工程においてプラス極性に振れていたとしても、一様にマイナス側へ帯電極性を揃えることが出来る。これゆえ、現像方法として反転現像を用いた場合、トナーの現像されるべき明部電位部にはマイナスに帯電された、転写残余のトナーが残り、トナーの現像されるべきでない暗部電位には、現像電界の関係上トナー担持体の方に引き寄せられ、暗部電位をもつ感光体上にトナーは残留しない。
【０２１１】
しかしながら、より高速なプロセススピードでの画像形成を行おうとする場合には、感光体単位表面積あたりの帯電時間の減少に相関して、帯電部材により感光体表面と共に転写残余のトナーをも一様に帯電極性を揃えることが困難となる。これゆえ、現像方法として反転現像を用いた場合、トナーの現像されるべきでない暗部電位上の転写残トナーが、現像電界によってトナー担持体の方に引き寄せられ回収することをも困難となる。また、トナー担持体に摺擦等の機械的力によって回収されたとしても、転写残トナーの帯電が均一に揃えられていないと、トナー担持体上のトナーの帯電性に悪影響を及ぼし、現像特性を低下させる。また、帯電部材の汚染による帯電不良も起こしやすくなる。
【０２１２】
感光体の帯電と同時に転写残余のトナーの帯電極性を制御することにより、現像同時クリーニング、クリーナレス画像形成方法が成立する。
【０２１３】
転写残トナーの現像での回収性向上には、帯電極性制御がより迅速に行われなばならず、現像性能の保持には、帯電部材を通過する際、転写残トナーがより確実に且つ均一に帯電極性制御されねばならない。
【０２１４】
特に、帯電部材と感光体を当接させ帯電を行う、いわゆる接触帯電法においては、その帯電機構として所謂パッシェンの法則に従う放電を利用した場合においては、帯電部材が感光体に接触している事および放電エネルギーによるトナー劣化に起因する帯電部材への付着性の悪化も生ずる。
【０２１５】
従来は、ブレード又は、ファーブラシなどのクリーニング部材により、転写残余のトナーが感光体上からクリーニングされており、感光体上に存在するトナーの帯電、現像装置での回収性及びこのトナーが現像装置内に回収され再利用される際の現像性能への影響を考慮にいれた検討は行われていなかった。
【０２１６】
本発明者らは、様々なトナーについて鋭意検討した。その結果、現像同時クリーニング、クリーナレス画像形成方法においては、特定の形状を有し、特定の無機微粉体及び有機樹脂微粒子と、特定のアゾ系鉄錯体化合物を用いることで、トナーの帯電部材通過時の帯電制御特性が改善され、これら耐久特性、画像品質特性に密接なつながりがある。
【０２１７】
以下、本発明の画像形成方法に適用可能な接触転写工程について具体的に説明する。
【０２１８】
接触転写工程とは、感光体表面に転写材を介して転写手段を当接させながら現像画像を転写材に静電転写するものであるが、転写手段の感光体表面に対する当接圧力としては線圧２．９Ｎ／ｍ（３ｇ／ｃｍ）以上であることが好ましく、より好ましくは９．８〜４９０Ｎ／ｍ（１０〜５００ｇ／ｃｍ）以上である。当接圧力としての線圧が２．９Ｎ／ｍ（３ｇ／ｃｍ）未満であると、転写材の搬送ずれや転写不良の発生が起こりやすくなるため好ましくない。当接圧力が高すぎる場合には、感光体の劣化や、感光体表面へのトナー融着を生じるようになる。
【０２１９】
また、接触転写工程における転写手段としては、転写ローラーあるいは転写ベルトを有する装置が使用される。転写ローラーは少なくとも芯金と芯金を被覆する導電性弾性層を有し、導電性弾性層はカーボン等の導電性微粒子を分散させたウレタンやＥＰＤＭ等の、体積抵抗１０⁶〜１０¹⁰Ωｃｍ程度の弾性体で作られている。
【０２２０】
また、本発明は、直径が５０ｍｍ以下の小径のドラム状感光体を有する画像形成装置に対し特に有効に用いられる。即ち、小径の感光体ドラムの場合には、同一の線圧での接触部材の当接部における圧力の集中が起こりやすいためである。ベルト感光体でも同一の現象があると考えられるが、本発明は、当接部での曲率半径が２５ｍｍ以下の画像形成装置に対しても有効である。
【０２２１】
さらに本発明においては、トナーの現像に際しては、トナーの総帯電量をコントロールすることが望ましく、本発明に係わるトナー担持体の表面は導電性微粒子及び／又は滑剤を分散した樹脂層で被覆されていることが好ましい。
【０２２２】
帯電方法としては、コロトロンあるいはスコロトロンなどと呼ばれる公知のコロナ帯電方法が用いられるほか、ピン電極を用いた方法等も使用できる。また、接触帯電法も同様に使用できる。
【０２２３】
本発明は、帯電手段が帯電部材を感光体表面に当接させる接触帯電法の場合に特に効果的である。すなわち、帯電手段が感光体表面に接することのない非接触のコロナ放電等に比べて、接触帯電法は感光体表面の劣化を生じ易く、耐久性の観点から転写性の低下による転写残トナーの増加がクリーニング性に厳しい方向にあるためである。従って、本発明の高転写性の効果はより顕著となる。
【０２２４】
接触帯電部材として、帯電ローラーを用いたときの好ましいプロセス条件としては、帯電ローラーの当接圧が４．９〜４９０Ｎ／ｍ（５〜５００ｇ／ｃｍ）で、転写残トナーの極性を感光体帯電極性と同じ極性に揃え、現像時での回収を容易にするため、直流電圧の印加がよいが、直流電圧に交流電圧を重畳したものを用いたときには、２×Ｖｔｈ（Ｖ）［Ｖｔｈ；直流印加における放電開始電圧（Ｖ）］未満のピーク間電圧を有する交流電圧を直流電圧に重畳することが好ましい。
【０２２５】
この他の接触帯電部材としては、帯電ブレードを用いる方法や、導電性ブラシを用いる方法がある。これらの接触帯電手段は、高電圧が不要になったり、オゾンの発生が低減するといった効果がある。
【０２２６】
接触帯電部材としては、ローラーまたはブレードの場合は、導電性基体として、鉄、銅、ステンレス等の導電性金属、カーボン分散樹脂、金属あるいは金属酸化物分散樹脂などが用いられる。その形状としては棒状、板状等が使用できる。例えば、弾性ローラーの構成としては、導電性基体上に弾性層、導電層、抵抗層を設けたものが用いられる。ローラー弾性層としては、クロロプレンゴム、イソプレンゴム、ＥＰＤＭゴム、ポリウレタンゴム、エポキシゴム、ブチルゴムなどのゴム又はゴムの発泡体であるスポンジや、スチレン−ブタジエンサーモプラスチックエラストマー、ポリウレタン系サーモプラスチックエラストマー、ポリエステル系サーモプラスチックエラストマー、エチレン−酢ビサーモプラスチックエラストマー等のサーモプラスチックエラストマーなどで形成することができる。導電層としては、体積抵抗率を１０⁷Ω・ｃｍ以下とすることが好ましく、１０⁶Ω・ｃｍ以下であることがより好ましい。例えば、金属蒸着膜、導電性粒子分散樹脂、導電性樹脂等が用いられ、具体例としては、アルミニウム、インジウム、ニッケル、銅、鉄等の金属の蒸着膜、カーボン、アルミニウム、ニッケル、酸化チタンなどの導電性粒子をウレタン、ポリエステル、酢酸ビニル−塩化ビニル共重合体、ポリメタクリル酸メチル等の樹脂中に分散した導電性粒子分散樹脂などが挙げられ、４級アンモニウム塩含有ポリメタクリル酸メチル、ポリビニルアニリン、ポリビニルピロール、ポリジアセチレン、ポリエチレンイミンなどの導電性を有する樹脂が挙げられる。抵抗層は、例えば、体積抵抗率が１０⁶〜１０¹²Ω・ｃｍの層であることが好ましく、半導性樹脂、導電性粒子分散絶縁樹脂等を用いることができる。半導性樹脂としては、エチルセルロース、ニトロセルロース、メトキシメチル化ナイロン、エトキシメチル化ナイロン、共重合ナイロン、ポリビニルヒドリン、カゼイン等が用いられる。導電性粒子分散樹脂の例としては、カーボン、アルミニウム、酸化インジウム、酸化チタンなどの導電性粒子をウレタン、ポリエステル、酢酸ビニル−塩化ビニル共重合体、ポリメタクリル酸メチル等の絶縁性樹脂中に少量分散したものなどが挙げられる。
【０２２７】
接触帯電部材としてのブラシは、一般に用いられている繊維に導電材を分散させて抵抗調整されたものが用いられる。繊維としては、一般に知られている繊維が使用可能であり、例えばナイロン、アクリル、レーヨン、ポリカーボネート、ポリエステル等が挙げられる。また導電材としては、一般に知られている導電材が使用可能であり、銅、ニッケル、鉄、アルミニウム、金、銀等の金属あるいは酸化鉄、酸化亜鉛、酸化スズ、酸化アンチモン、酸化チタン等の金属酸化物、さらにはカーボンブラック等の導電粉が挙げられる。なおこれら導電材は必要に応じ疎水化、抵抗調整の目的で表面処理が施されていてもよい。使用に際しては、繊維との分散性や生産性を考慮して選択して用いる。ブラシの形状としては、繊維の太さが１〜２０デニール（繊維径１０〜５００μｍ程度）、ブラシの繊維の長さは１〜１５ｍｍ、ブラシ密度は１平方インチ当たり１万〜３０万本（１平方メートル当り１．５×１０⁷〜４．５×１０⁸本程度）のものが好ましく用いられる。
【０２２８】
【実施例】
以下、トナーおよび感光体ドラムの具体的な製造方法、実施例、比較例をもって本発明をさらに詳細に説明する。
【０２２９】
表１に示すカーボンブラックを用意した。
【０２３０】
【表１】

【０２３１】
これらのカーボンブラックを用いて表２に示すような組成の前分散液を用意した。表２の処方をメディア分散機で３時間撹拌分散し、前分散処理後の分散液の粘度を測定した。
【０２３２】
【表２】

【０２３３】
上記の前分散液を用いて、表３の処方を組みトナー粒子を作製した。この際、含有するカーボンブラックの比率を一定に設定した。
【０２３４】
なお、ポリエステル樹脂は、プロポキシ化ビスフェノールとテレフタル酸を縮合して得られた、ピーク分子量６０００、酸価１０〜２０のポリエステル樹脂を用いた。
【０２３５】
【表３】

【０２３６】
以下にトナーの製造例を示す。
【０２３７】
［重合トナーの製造例Ａ］
２リットル用四つ口フラスコ中のイオン交換水７００ｇに、０．ｌＭ−Ｎａ₃ＰＯ₄水溶液５００ｇを投入し、６０℃に加温した後、高速撹拌装置ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂水溶液７６ｇを徐々に添加し、微小な難水溶性分散安定剤を含む水系媒体を得た。
【０２３８】
一方、前分散工程として
（モノマー）スチレン ２０００ｇ
（着色剤）カーボンブラックａ １６０ｇ
（分散助剤・荷電制御剤）アゾ系鉄錯体化合物（１） ４０ｇ
上記処方をメディア分散機で３時間撹拌し、前分散処理を行った。前分散処理後の分散液の粘度を測定したところ、４６０センチポイズの粘度を有していた。さらに、分散質として、

上記処方を６０℃に加温、均一に溶解し、分散した。これに、重合開始剤２，２’−アゾビス（２，４−ジメチルバレロニトリル）１０ｇを溶解し、重合性単量体組成物を調製した。
【０２３９】
前記水系媒体中に上記重合性単量体組成物を投入し、６５℃，Ｎ₂雰囲気下において、ＴＫ式ホモミキサーにて１２０００ｒｐｍで１０分間撹拌し、重合性単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ（１００ｒｐｍ）、同温度で５時間反応させた後、８０℃に昇温し、さらに５時間反応させた。重合反応終了後、減圧下で残存モノマーを留去し、冷却後、塩酸を加えリン酸カルシウムを溶解させた後、ろ過、水洗、乾燥して、重量平均径約６．７μｍのシャープな黒色懸濁粒子（トナー粒子）を得た。
【０２４０】
得られたトナー粒子１００重量部に対して、無機微粉体として表４に示す疎水性シリカ（ａ）を１．５重量部及び重合体微粒子として表５に示すポリメチルメタクリレート微粒子（ｈ）０．２重量部を外添し、重合トナーＡを得た。得られた重合トナーＡを、日立製作所製ＦＥ−ＳＥＭ（Ｓ−８００）を用い１０００倍に拡大した２μｍ以上のトナー像を１００個無作為にサンプリングし、ニコレ社製画像解析装置（ＬｕｚｅｘＩＩＩ）に導入し解析を行い、形状係数を求めたところ、トナー粒子の形状係数は、ＳＦ−１が１１７、ＳＦ−２が１１５であった。
【０２４１】
［重合トナーの製造例Ｂ〜Ｄ］
０．１Ｍ−Ｎａ₃ＰＯ₄水溶液と１．０Ｍ−ＣａＣｌ₂水溶液の量、添加する極性レジンの飽和ポリエステルの添加量及び酸価を調整することで形状係数ＳＦ−１、ＳＦ−２の異なるトナーを［重合トナーの製造例Ａ］と同様にして重合トナーＢ〜Ｄを作製した。得られたトナーの物性を表６に示した。
【０２４２】
［重合トナーの比較製造例Ｅ，Ｆ］
０．１Ｍ−Ｎａ₃ＰＯ₄水溶液と１．０Ｍ−ＣａＣｌ₂水溶液の量、造粒時の水系媒体のｐＨ、及び添加する極性レジンの飽和ポリエステルの添加量及び酸価を調整することで形状係数ＳＦ−１、ＳＦ−２の異なるトナーを［重合トナーの製造例Ａ］と同様にして重合トナーＥ，Ｆを作製した。得られたトナーの物性を表６に示した。
【０２４３】
［重合トナーの製造例Ｇ，Ｈ］
０．ｌＭ−Ｎａ₃ＰＯ₄水溶液と１．０Ｍ−ＣａＣｌ₂水溶液の量を調整することで粒度の異なるトナーを［重合トナーの製造例Ａ］と同様にして重合トナーＧ，Ｈを作製した。得られたトナーの物性を表６に示した。
【０２４４】
［重合トナーの製造例Ｉ］
カーボンブラックａのかわりに表１に示すカーボンブラックｂを使用した前分散液Ｎｏ．２を用い、無機微粉体として疎水性シリカ（ｂ）を１．２重量部及び重合体微粒子として粒径０．１５μｍであるポリメチルメタクリレート微粒子（ｊ）０．１重量部を外添した以外は［重合トナーの製造例Ａ］と同様にして重合トナーＩを作製した。また、得られたトナーの物性を表６に示した。
【０２４５】
［重合トナーの製造例Ｊ〜Ｍ］
アゾ系鉄錯体化合物（１）の添加量を変更した前分散液Ｎｏ．３〜６を用いた以外は［重合トナーの製造例Ｉ］と同様にして重合トナーＪ〜Ｍを作製した。得られたトナーの物性を表６に示した。
【０２４６】
［重合トナーの比較製造例Ｎ］
アゾ系鉄錯体化合物を未添加とした前分散液Ｎｏ．７を用いた以外は［重合トナーの製造例Ｉ］と同様にして重合トナーＮを作製した。得られたトナーの物性を表６に示した。
【０２４７】
［重合トナーの製造例Ｏ〜Ｘ］
カーボンブラックａのかわりにカーボンブラックｃ〜ｌを用い、無機微粉体として疎水性シリカ（ｄ）を１．０重量部及び重合体微粒子として粒径０．４μｍであるポリメチルメタクリレート微粒子（ｋ）０．１重量部を外添した以外は［重合トナーの製造例Ａ］と同様にして重合トナーＯ〜Ｘを作製した。ただし、カーボンブラックｋを用いた重合トナーＷは、前分散が不均一となり造粒できず、トナーとして得ることができなかった。得られたトナーの物性を表６に示した。
【０２４８】
【表４】

【０２４９】
【表５】

【０２５０】
【表６】

【０２５１】
（感光体製造例１）
感光体としては３０φ、２５４ｍｍのアルミニウムシリンダーを基体とした。これに、次に示すような構成の層を順次浸漬塗布により積層して、感光体を作製した。
【０２５２】
（１）導電性被覆層：酸化錫及び酸化チタンの粉未をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
【０２５３】
（２）下引き層：変性ナイロン及び共重合ナイロンを主体とする。膜厚０．６μｍ。
【０２５４】
（３）電荷発生層：長波長域に吸収を持つアゾ顔料をブチラール樹脂に分散したものを主体とする。膜厚０．６μｍ。
【０２５５】
（４）電荷輸送層：ホール搬送性トリフェニルアミン化合物をポリカーボネート樹脂（オストワルド粘度法による分子量２万）に８：１０の重量比で溶解したものを主体とし、さらにポリ４フッ化エチレン粉体（粒径０．２μｍ）を総固形分に対して１０重量％添加し、均一に分散した。膜厚２５μｍ。
【０２５６】
得られた感光体の表面の水に対する接触角は９５度であった。
【０２５７】
なお、接触角の測定は、純水を用い、装置は、協和界面科学（株）、接触角計ＣＡ−ＤＳ型を用いた。
【０２５８】
（感光体製造例２）
電荷輸送層にポリ４フッ化エチレン粉体（粒径０．２μｍ）を添加しなかったことを除いて感光体製造例１と同様に膜厚２５μｍの電荷輸送層を形成し、感光体を作製した。得られた感光体の表面の水に対する接触角は７９度であった。
【０２５９】
＜実施例１＞
画像形成装置として６００ｄｐｉのレーザービームプリンタ（キヤノン製：ＬＢＰ−８３０）を用意した。この装置を改造し、プロセススピード８０ｍｍ／ｓ（トナー担持体スピード可変）、Ａ４サイズ紙で毎分１６枚プリントとした。図１に示すように、この装置は直流及び交流成分を印加したローラー３２を用い感光体２６（３０φ）を一様に帯電する。帯電に次いで、レーザー光２０で画像部分を露光することにより静電潜像を形成し、トナー３３により可視画像とした後に、電圧を印加した転写ローラー２７によりトナー像を転写材２８に転写するプロセスを持つ。転写材上のトナー画像は、加熱ローラと加圧ローラとを有する加熱加圧定着手段３１により定着される。
【０２６０】
また、クリーニングブレードを除去し、転写残のトナーは現像時に同時に現像器内に回収する現像同時クリーニングシステムとした。
【０２６１】
次に、プロセスカートリッジにおける現像容器２２を改造した。トナー供給体であるマグネットを内包したアルミニウムスリーブの代わりにカーボンブラックを分散して抵抗を調整したシリコーンゴムからなる中抵抗ゴムローラ（１６φ）をトナー担持体２４とし、感光体２６に当接した。該トナー担持体の回転周速は、感光体との接触部分において同方向であり、該感光体回転周速に対し１５０％となるように駆動する、つまり、該トナー担持体の周速は１２０ｍｍ／ｓであり、感光体表面に対する相対速度は４０ｍｍ／ｓである。
【０２６２】
トナー担持体にトナーを塗布する手段として、現像部分に塗布ローラー２５を設け、該トナー担持体に当接させた。接触部においてトナー担持体と反対方向に回転することによりトナーをトナー担持体上に塗布した。さらに、該トナー担持体上トナーのコート層制御のために、樹脂をコートしたステンレス製ブレード２３を取付けた。
【０２６３】
感光体は（感光体製造例１）を用い、トナーはトナーＡを用い、以下の現像条件を満足するようプロセス条件を設定した。
【０２６４】
感光体暗部電位（Ｖ_D） −７００Ｖ
感光体明部電位（Ｖ_L） −１５０Ｖ
現像バイアス（Ｖ_DC） −４００Ｖ（直流成分のみ）
【０２６５】
反転現像方法において、現像同時クリーニングを実施するための好ましい現像条件としては、感光体表面の暗部電位（Ｖ_D）と明部電位（Ｖ_L）とトナー担持体に印加される直流バイアス（Ｖ_DC）とが、｜Ｖ_D−Ｖ_DC｜＞｜Ｖ_L−Ｖ_DC｜の関係を満足するように設定するのが良い。より好ましくは｜Ｖ_D−Ｖ_DC｜の値が｜Ｖ_L−Ｖ_DC｜の値よりも１０Ｖ以上大きい方が良い。
【０２６６】
印字比率４％文字Ａ４を１０００枚の連続画出し試験を行い、画像評価を行ったところ、画像濃度、感光体上カブリ抑制、転写性ともに良好であり、初期と同等の画像品質を得た。転写材としては、７５ｇ／ｍ²の紙を用いた。また、感光体、現像ローラ共に観察したが、融着等もなく交換することを必要としなかった。更にトナー表面をＳＥＭ観察したところ、１０００枚の連続画出し後のトナー担持体近傍トナーでもトナー容器に充填する前の初期のトナーと比較して、トナー表面の無機微粉体及び重合体微粒子の様子に変化はほとんど見られなかった。
【０２６７】
なお、本発明中において飛び散りの評価は、グラフィカルな画像の画質に関わる微細な細線での飛び散り評価であり、文字ラインにおける飛び散りよりも、より飛び散りやすい１ドットラインでの飛び散り評価である。
【０２６８】
また、解像力は潜像電界によって電界が閉じやすく、再現しにくい図２に示す様な６００ｄｐｉの５０μｍ小径孤立ドットの再現性によって評価した。
【０２６９】
転写性はベタ黒の感光体上の転写残トナーを、カブリはベタ白の感光体上の転写残トナーを、それぞれマイラーテープによリテーピングしてはぎ取り、紙上に貼ったもののマクベス濃度から、テープのみを貼ったもののマクベス濃度を差し引いた数値で評価した。したがって、値の小さいほど転写性・カブリ抑制ともに良好である。
【０２７０】
また、１００枚めの画像の帯電不良による汚れを評価した。印字比率４％文字を１０００枚プリントした後にも、画像濃度及び画像汚れを評価した。さらに帯電ローラー単位表面積（ｃｍ²）あたりのトナー付着量（ｍｇ）を測定した。
【０２７１】
画像汚れは
◎：未発生
○：かすかに発生だが実用可
△：発生量は少ないが実用不可
×：著しく発生し実用不可
の基準で評価した。すなわち、よく観察しないとわからないような画像汚れを除き、すべて実用不可とした。
【０２７２】
帯電ローラの汚れは、帯電ローラ上の単位面積当たりのトナー重量（ｍｇ／ｃｍ²）を測定した。
【０２７３】
転写性、カブリ、画像濃度、解像力は実施例１と同様にして評価した。
【０２７４】
結果は表７に示すように、高濃度で画像汚れのない高品質の画像が得られた。
【０２７５】
＜実施例２＞
下記以外は実施例１と同様にして行った。
【０２７６】
トナー担持体の回転周速を、感光体との接触部分において同方向であり、該感光体回転周速に対し２００％となるように駆動した。該トナー担持体の周速は１６０ｍｍ／ｓであり、感光体表面に対する相対速度は８０ｍｍ／ｓである。
【０２７７】
トナーはトナーＢを用い、以下の現像条件を満足するようプロセス条件を設定した。
【０２７８】
現像バイアス −５００Ｖ（直流成分のみ）
【０２７９】
トナーを補給しつつ１０００枚の耐久試験を行ったが、画像濃度、カブリ抑制、転写性ともに良好であり、クリーニング不良も発生せず、初期と同等の画像品質を得た。また、感光体、現像ローラー共に観察したが、融着等もなく交換することを必要としなかった。評価結果を表７に示す。
【０２８０】
＜実施例３〜５＞
トナーとして、重合トナーＢ〜Ｄを使用する以外は実施例１と同様にして評価した。結果は表７に示すように、概ね良好な結果を得た。
【０２８１】
＜比較例１，２＞
実施例１において、重合トナーＥ，Ｆと感光体製造例２の感光体を用いたほかは同様の試験を行った。
【０２８２】
以下の現像条件を満足するようプロセス条件を設定した。
【０２８３】
現像バイアス −３５０Ｖ（直流成分のみ）
【０２８４】
重合トナーＥでは、１００枚時に著しい帯電不良による著しい画像不良が発生した。重合トナーＦでは、１００枚時にカブリがやや多く、１０００枚時には帯電不良による著しい画像不良が発生した。
【０２８５】
また、重合トナーＥ，Ｆとも５０μｍの孤立ドットの再現が不十分でライン画像も飛び散りが目立つものであった。
【０２８６】
その結果を表７に示した。
【０２８７】
【表７】

【０２８８】
＜実施例６〜１１＞
トナーとして、重合トナーＧ，Ｈをもとに、添加する無機微粉体及び有機微粒子を表８に示すようにした重合トナーＧａ〜Ｇｃ，Ｈａ〜Ｈｃを使用する以外は実施例１と同様にして評価した。結果は表１０に示すように、概ね良好な結果を得た。
【０２８９】
＜比較例３＞
トナーとして、重合トナーＧをもとに、表８に示すように無機微粉体を添加しない重合トナーＧｄを使用する以外は実施例１と同様にして評価した。結果は表１０に示すように、初期１００枚よりカブリ抑制が悪く、転写性も良くなく、帯電部材の汚染により画像汚れを生じた。
【０２９０】
【表８】

【０２９１】
＜実施例１２〜１９＞
トナーとして、重合トナーＩをもとに、添加する無機微粉体及び有機微粒子を表９に示すようにした重合トナーＩａ〜Ｉｊを使用する以外は実施例１と同様にして評価した。結果は表１０に示すように、概ね良好な結果を得た。
【０２９２】
＜比較例４＞
トナーとして、重合トナーＩをもとに、表９に示すように有機微粒子を添加しない重合トナーＩｋを使用する以外は実施例１と同様にして評価した。結果は表１０に示すように、初期１００枚より転写性がやや悪く、１０００枚後には帯電部材の汚染により画像汚れを生じた。
【０２９３】
【表９】

【０２９４】
【表１０】

【０２９５】
＜実施例２２、参考例１、実施例２４及び２５、参考例２＞
トナーとして、重合トナーＩ〜Ｍを使用する以外は実施例１と同様にして評価した。結果は表１１に示すように、概ね良好な結果を得た。
【０２９６】
＜比較例５＞
トナーとして、重合トナーＮを使用する以外は実施例１と同様にして評価した。結果は表１１に示すように、カブリ抑制が悪く、クリーニング不良による顕著な画像汚れを生じ、画像濃度が低かった。
【０２９７】
＜実施例２７〜３５＞
トナーとして、重合トナーＯ〜Ｖ及びＸを使用する以外は実施例１と同様に評価した。結果は表１１に示すように、重合トナーＯ〜Ｕについては概ね良好な結果を得たが、重合トナーＶでは、初期に画像濃度がやや低く、徐々に画像濃度が上昇し、その後画像濃度は安定した。重合トナーＸでは、画像濃度がやや低かった。
【０２９８】
【表１１】

【０２９９】
＜参考例３＞
プロセスカートリッジ概略を図５に示すように、実施例１に用いた画像形成装置にクリーニング部材を取りつけ、転写残トナーをクリーニング部材で感光体表面から掻き取り、廃トナーとして回収する構成とした画像形成装置を用意した。
【０３００】
トナーとして、実施例１２で用いた重合トナーＩａを使用し、帯電不良による画像汚れの評価に代わり、クリーニング不良による画像汚れの程度を評価項目とする以外は、実施例１と同様に評価した。結果は表１２に示すように、１０００枚目まで、クリーニング不良を生ずることなく良好な画像が得られた。
【０３０１】
更に５０００枚の連続画出し後のトナー担持体近傍トナーにおいてトナー表面をＳＥＭ観察したところ、トナー容器に充填する前の初期トナーと比較して、トナー表面の無機微粉体及び有機微粒子の様子に変化はほとんど見られなかった。
【０３０２】
＜比較例６＞
トナーとして、比較例４で用いた重合トナーＩｋを使用する以外は参考例３と同様にして評価した。結果は表１２に示すように、参考例３と比較して転写性に劣り、１０００枚目ではクリーニング不良による画像汚れを僅かに生じ、カブリ抑制も悪化していた。
【０３０３】
＜参考例４＞
トナーとして、実施例１で用いた重合トナーＡを使用する以外は、参考例３と同様に評価した。結果は表１２に示すように、１０００枚目まで、クリーニング不良を生ずることなく良好な画像が得られた。
【０３０４】
＜比較例７＞
トナーとして、比較例１で用いた重合トナーＥを使用する以外は参考例３と同様にして評価した。結果は表１２に示すように、参考例４と比較して転写性に劣り、１０００枚目では重合体微粒子のクリーニング部材からのすり抜けが原因と考えられるポチ状のカブリが発生し、転写性も更に低下しクリーニング不良による画像汚れを生じた。
【０３０５】
【表１２】

【０３０６】
【発明の効果】
以上説明したように、本発明によれば、マシンの高速化、長寿命化に対応し得る、トナー帯電の迅速な立ち上がりによる高品位な画像性と、転写性を得ることが可能である。また、流動性、長期保存性、耐環境特性、耐久性を損なうことなく、感光体上カブリを安定的に低減させることが可能である。
【０３０７】
更に、本発明によれば、本発明のトナーを現像同時クリーニングの構成に適用することによって、感光体上の現像トナーの帯電量を適正に制御し、転写残トナーやカブリトナーの悪影響による、現像工程でのクリーニング性の低下を防止すると同時に、定着性能と耐久性能を長期にわたり両立できることが可能である。
【０３０８】
また、接触一成分現像においても過剰な帯電が抑制された良好なトナー担持体上での帯電制御性により、優れた現像特性が得られる。
【図面の簡単な説明】
【図１】本発明の画像形成方法の実施例の一例として用いた、現像同時クリーニングシステムを用いた画像形成方法を模式図に示した図である。
【図２】解像性を評価するための円形スポット模様の説明図である。
【図３】本発明に係わるカーボンブラック及びアゾ系鉄錯体化合物をスチレン中で分散したときの粘度変化を示す図である。
【図４】本発明に係わるカーボンブラックにおいて、一定量のアゾ系鉄錯体化合物を添加しスチレン中で分散したときのカーボンブラックの吸油量と粘度の関係を示す図である。
【図５】本発明の画像形成方法の実施例の一例として用いた、接触一成分現像装置を用いた画像形成方法を模式図に示した図である。
【符号の説明】
２２ 現像容器
２３ トナー規制ブレード
２４ トナー担持体（弾性ローラー）
２５ トナー塗布ローラー
２６ 感光体（像担持体）
２７ 転写ローラー
２８ 転写材
３０ バイアス印加手段
３１ 定着器
３２ 帯電ローラー
３３ トナー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method using electrophotography, electrostatic recording, magnetic recording, or the like. More specifically, the present invention relates to an image forming method and a toner used in a copying machine, a printer, and a fax machine, in which a toner image is formed on a photoreceptor in advance and then transferred onto a transfer material to form an image.
[0002]
[Prior art]
Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is formed with toner. Development is performed to form a visible image, and the toner image is transferred to a transfer material such as paper as necessary, and then the toner image is fixed on the transfer material by heat and pressure to obtain a fixed image. At this time, the toner remaining on the photoreceptor without being transferred to the transfer material after the transfer is cleaned by various methods, and the above-described steps are repeated.
[0003]
As a developer for developing the electrostatic latent image formed on the surface of the photoreceptor, a two-component developer composed of a carrier and a toner, and a one-component developer that does not require a carrier (magnetic toner, non-magnetic toner). )It has been known. In the two-component system, the toner is charged mainly by friction between the carrier and the toner, and in the one-component system, the toner is charged mainly by friction between the toner and the charge imparting member.
[0004]
As a developer, regardless of the difference between a two-component developer and a one-component developer, a method of adding inorganic fine powder such as silica to the toner particles for the purpose of improving the flow characteristics and charging characteristics of the toner is proposed. And widely used.
[0005]
However, inorganic fine powders that are highly effective in improving toner flow characteristics and charging characteristics have an average particle size that is very small compared to the average particle size of toner particles and has a high hardness. Alternatively, the toner particles are easily embedded in the surface of the toner particles due to friction between the toner particles and the charge imparting member, and as a result, it is difficult to maintain the chargeability and fluidity characteristics of the developer over a long period of time. When inorganic fine particles having an average particle diameter of about 0.1 to 2 μm are mixed with toner particles, the inorganic fine particles adhering to the toner particle surfaces are statically absorbed although the inorganic fine particles are hardly embedded in the toner particle surfaces by friction. There is a problem that the surface of the electrostatic latent image holding member or the toner carrying member is damaged and the print quality is deteriorated.
[0006]
Further, a developer in which inorganic particles or polymer fine particles known in the art are mixed with toner particles can prevent the toner particles from adhering to the surface of the photoreceptor and can improve the cleaning property, but the toner particles have a triboelectric charging ability. When the developer is used over a long period of time, there is a problem that image density is lowered and fogging occurs.
[0007]
In addition, a developer in which an acrylic polymer fine powder or an acrylic / styrene copolymer fine powder having an average particle size smaller than the average particle size of the toner is added to the toner as the polymer fine particles has been proposed. JP-A-60-186851, JP-A-60-186852, JP-A-60-186854). These polymer fine powders have an average particle size of 0.005 to 5 μm, preferably 0.1 to 2 μm, and the developer mixed therewith can be used for cleaning without damaging the surface of the photoreceptor or toner carrier. It is said that the property can be improved and the developer life can be extended. However, according to the examination results of the present inventors, when a developer is used for a long period of time, there is a problem that the triboelectric charging ability of the toner particles is reduced, and the image density is lowered and fogging occurs. It has been found that the charging ability is not always satisfactory.
[0008]
As a method of using inorganic fine powder and polymer fine particles in combination, for example, as disclosed in JP-A-1-116648, 0.05 to 1% by weight of silica fine powder with respect to toner particles and polymethyl methacrylate type are used. Method using polymer fine particles; the ratio of polymethyl methacrylate fine powder to silica fine powder is 1: (0.50 to 3.0) as in JP-A-2-91659, and the addition There is a method of adjusting the total amount of fine particles to be 0.75 to 1.55% by weight with respect to the toner particles.
[0009]
It has been found that the above-mentioned methods cause a problem (fogging on the photoconductor) that the toner adheres to the non-latent image forming portion of the photoconductor in a trace amount as the development speed increases. The toner adhering to the non-latent image forming part is difficult to be transferred in the transfer process, and it is necessary to secure a large space for storing the waste toner removed in the cleaning process, and the machine speed, size and print volume are increased. It is becoming impossible to fully satisfy today's demands.
[0010]
It is also known that an azo-based iron complex compound is contained in the toner as a charge control agent that improves the charging characteristics of the toner.
[0011]
In Japanese Patent Application Laid-Open Nos. 61-155464 and 62-177561, azo-based iron complexes are known as charge control agents having good dispersibility in the binder resin. The toner containing the azo-based iron complex has a slow charge increase rate, and the image density decreases when left for a long period of time or under high humidity. In recent years, a reduction in toner particle size (weight average diameter of 9 μm or less) has been promoted in order to improve image quality. The toner with small particle size has a significantly increased charge amount under low humidity, and the reverse polarity due to thinning of the line image, lowering of the image density, and inhibition of charging of the toner on the toner carrier by the excessively charged toner. As a result, charged toner is generated, and reversal potential fogging occurs.
[0012]
In order to improve the chargeability of toner using such an azo-based iron complex as a charge control agent, Japanese Patent Application Laid-Open No. 2-153362 proposes a developing device in which a toner layer thickness regulating member, a toner replenishing auxiliary member, and the like are improved. ing. The developing property of the toner is maintained by the charge imparting member, and it is difficult to maintain a good image for a long time due to problems such as deterioration and contamination of the charge imparting member.
[0013]
It is also widely known that carbon black is contained as a black colorant in a toner. Carbon black is known to have a great influence on its dispersibility due to physical properties such as primary particle size, specific surface area, structure structure, surface properties (functional groups on the surface, etc.), and contains carbon black in the toner. It is also known that the selection greatly affects the toner characteristics.
[0014]
For example, carbon black is very difficult to disperse because it has a small primary particle size, a large specific surface area, and a structure structure compared to other pigments. If the dispersibility of carbon black in the toner particles is insufficient, the chargeability of the toner is impaired, toner scattering occurs, and fogging occurs during development. In addition, adverse effects such as low image density or increased toner consumption occur.
[0015]
As a method for visualizing an electric latent image, a cascade development method, a magnetic brush development method, a nonmagnetic one-component development method, a pressure development method, and the like are known. Furthermore, a magnetic one-component developing method is also used in which a magnetic toner is used and a rotating sleeve having a magnetic pole at the center is used to fly between the photosensitive member and the sleeve by an electric field.
[0016]
In recent years, as an image forming method having a configuration in which the surface of the photoconductor is rubbed with toner and a toner carrier, a configuration in which the surface is pressed against the surface of the photoconductor using a semiconductive developing roller or a developing roller having a dielectric layer formed on the surface is used. A so-called contact one-component development method has been proposed.
[0017]
In the one-component development method, if the photosensitive member and the toner carrier have a distance, the electric force lines concentrate on the edge portion of the electrostatic latent image on the photosensitive member, and the toner is developed along the electric force lines. Image quality is likely to deteriorate due to an edge effect in which toner is biased and developed at the edge portion of the image. In the contact one-component development method, since the surface of the photoreceptor and the development electrode are very close to each other, advantages such as reduction of the edge effect of development have been pointed out.
[0018]
However, there are demerits caused by the contact between the surface of the photoreceptor and the toner carrier, and there is a limit to the application range. It is difficult to mechanically set the gap between the photoconductor and the toner carrier, that is, to set the gap smaller than the thickness of the toner layer on the toner carrier.
[0019]
Therefore, the toner carrier is pressed against the photoconductor to prevent the edge effect. However, if the toner carrier surface moving speed is the same as the photoconductor surface moving speed, the latent image on the photoconductor is visualized. In this case, a satisfactory image cannot be obtained. In other words, there is a difference in the toner carrier surface moving speed with respect to the photosensitive member surface moving speed, and the toner on the toner carrier is developed with respect to the latent image on the photosensitive member. A developed image without a very faithful edge effect is obtained.
[0020]
Japan Hardcopy '89 Proceedings, pages 25 to 28, discusses a contact-type one-component non-magnetic development system. However, the durability characteristics are not mentioned.
[0021]
FUJITSU Sci. Tech. J. et al. , 28, 4, pp. 473-480 (December 992) reports an outline of a printer using a one-component contact development method. However, the durability characteristics are not sufficient and there is room for further improvement.
[0022]
Japanese Patent Laid-Open No. 5-188765 and Japanese Patent Laid-Open No. 5-188852 disclose techniques relating to a one-component contact development method, but no technique for improving durability.
[0023]
In other words, when such a development method is used, it is essential to rub the surface of the photoreceptor with the toner and the toner carrier. For this reason, toner deterioration due to long-term use, toner carrier surface degradation, photoreceptor surface degradation or wear. As a result, deterioration of durability characteristics remains as a problem, and this improvement method has been desired. Further, for this reason, there remains an essential problem that it is difficult to speed up the apparatus.
[0024]
In recent years, from the viewpoint of environmental protection, primary charging and transfer processes using a photoreceptor contact member are becoming mainstream.
[0025]
For example, Japanese Patent Laid-Open Nos. 63-149669 and 2-123385 have been proposed. In these methods, a conductive elastic roller is brought into contact with the photosensitive member, and the photosensitive member is uniformly charged while applying a voltage to the conductive roller, and then a toner image is obtained by an exposure and development process. While pressing another conductive roller to which a voltage is applied, a transfer material is passed between them to transfer the toner image on the photoconductor to the transfer material, and then a fixing image is obtained through a fixing step.
[0026]
However, in such a contact transfer method that does not use corona discharge, the transfer member is brought into contact with the photoconductor through the transfer material at the time of transfer, so that the toner image formed on the photoconductor is transferred to the transfer material. At this time, the toner image is brought into pressure contact, which causes a problem of partial transfer failure called so-called transfer omission.
[0027]
In addition, as the diameter of the toner decreases, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photosensitive member becomes larger than the Coulomb force applied to the toner particles during transfer, resulting in a residual transfer. There was a tendency for toner to increase.
[0028]
Accordingly, the toner and the photoreceptor used in such an image forming method are required to have excellent releasability.
[0029]
It is also known to define the shape of the toner in order to improve the transferability of the toner. For example, in JP-A-3-259161, non-magnetic one-component development in which the shape factor, the specific surface area, and the particle size are defined. A developer has been proposed, but the developer specified in the publication has insufficient durability.
[0030]
Japanese Patent Application Laid-Open No. 61-279864 proposes a toner that defines shape factors SF-1 and SF-2. However, there is no description about the transfer in this publication, and as a result of reexamining the examples, the transfer efficiency is low and further improvement is required.
[0031]
Furthermore, Japanese Patent Laid-Open No. 63-235953 proposes a magnetic toner that is spheroidized by a mechanical impact force. However, the transfer efficiency is still insufficient and further improvement is necessary.
[0032]
It is also known that a toner produced by a polymerization method that yields a substantially spherical toner is excellent in transferability. As an example, a toner by suspension polymerization has been proposed for a long time (for example, Japanese Patent Publication No. 36-10231). Japanese Patent Application Laid-Open No. 7-209952 discloses that a nearly spherical toner produced by suspension polymerization improves the releasability of the toner from the photoreceptor and improves the toner transferability.
[0033]
In this suspension polymerization method, a monomer composition is prepared by uniformly dissolving or dispersing a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives). Then, the monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer using a suitable stirrer and simultaneously subjected to a polymerization reaction, whereby a toner having a desired particle size is prepared. Particles are obtained.
[0034]
In this suspension polymerization method, droplets of the monomer composition are generated in a dispersion medium having a large polarity such as water. Therefore, the component having a polar group contained in the monomer composition is an interface with the aqueous phase. Therefore, it is possible to produce a substantially spherical toner having a so-called core / shell structure or sea-island structure in which a nonpolar component is easily present in the surface layer portion and does not exist in the surface layer portion.
[0035]
The toner by the polymerization method has been able to satisfy both conflicting performances such as low-temperature fixability, blocking resistance and high-temperature offset resistance by inclusion of a wax component as a release agent.
[0036]
When such a toner is used, it is difficult to expose the colorant to the surface, and there is an advantage that the toner has uniform triboelectric chargeability. Also, since the classification process can be omitted, the manufacturing cost reduction effect such as energy saving, time reduction, and process yield improvement is great.
[0037]
However, since the shape of the toner obtained by this method is substantially spherical, a cleaning defect due to toner particle abrasion occurs during cleaning in the above-described electrophotographic process, particularly blade cleaning. The quality of the resulting image may be significantly impaired.
[0038]
In particular, in non-magnetic one-component development, the charge amount of the toner developed on the photoconductor is high, and the adhesion force (mirror power) of the toner particles to the photoconductor is increased, and as a result, there is a tendency for the residual toner to increase. is there. There is a tendency that the charge amount of the transfer residual toner also tends to be high, and the adhesion force of the toner particles to the photosensitive member is also increased, so that a cleaning failure is likely to occur during cleaning.
[0039]
In addition, since the shape of the toner is substantially spherical, the inorganic fine powder added to the toner in order to improve the flow characteristics and charging characteristics of the toner is between the toner particles and the carrier particles or between the toner particles and the toner particles. By receiving the friction with the applying member more efficiently, the inorganic fine particles are easily embedded in the surface of the toner particles, in contrast to the excellent charging characteristics at the beginning, and the charging property and flow of the developer over a long period of time. It is difficult to maintain characteristics such as sex.
[0040]
Furthermore, when a toner is produced using carbon black as a pigment by the suspension polymerization method, a further problem occurs.
[0041]
First, since carbon black has functional groups on the surface that inhibit the polymerizability of monomers such as quinone groups, the polymerization rate slows and the degree of polymerization does not increase, and the particles become unstable during granulation, causing aggregation and coalescence. Cause a problem that makes it difficult to extract as particles.
[0042]
Secondly, a monomer composition is prepared by uniformly dissolving or dispersing a polymerizable monomer and carbon black (further, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives). At this time, carbon black is difficult to disperse in the monomer composition, and carbon black is unevenly distributed in the particles, or toner particles not containing carbon black are likely to be generated.
[0043]
Third, since carbon black is conductive, the charge on the surface of the toner is likely to leak, greatly affecting the chargeability of the toner. Variations in the carbon black content, dispersibility, and presence / absence of aggregation for each toner particle result in variations in the chargeability of the toner particles, leading to a decrease in development efficiency and an increase in fog.
[0044]
In particular, in non-magnetic one-component development, when toner particles having a low charge amount increase, the toner particles are scattered without being electrostatically attached and held on the toner carrying member, so that the inside of the apparatus and the image are stained. It tends to cause fog on the image. In addition, toner particles with a higher charge than necessary tend to increase the amount of residual toner after transfer to the photosensitive member (mirror power), and the charge amount of the residual toner tends to increase. In this case, cleaning defects are likely to occur. Furthermore, charging of other toner particles is inhibited to reduce the charge amount of the toner as a whole, which easily causes toner scattering and fogging.
[0045]
It is also known to contain an azo-based iron complex compound as a charge control agent in a toner by suspension polymerization.
[0046]
Japanese Patent Laid-Open No. 7-281485 proposes a suspension polymerization toner in which a specific azo-based iron complex compound is contained in a toner and the chargeability is improved by a nonmagnetic one-component development method. However, carbon black that greatly affects the polymerizability and chargeability of the toner has not been studied.
[0047]
On the other hand, in the application of electrophotography, LED and LBP printers have become the mainstream in the recent market, and smaller, lower-priced products in the direction of technology, further resource saving and consideration for the global environment Is demanded. In addition, copiers are required to have high reliability, higher image quality as digitalization progresses, resource saving, and consideration for the global environment.
[0048]
Conventionally, the toner image formed on the photoconductor in the development process is transferred to a transfer material in the transfer process, but the residual transfer toner remaining on the photoconductor is removed in a cleaning process such as blade cleaning, fur brush cleaning, or roller cleaning. The collected toner is collected and stored in the waste toner container.
[0049]
With respect to this cleaning process, any of the methods mechanically scrapes off the transfer residual toner or stops it and collects it in a waste toner container. Therefore, there has been a problem that the photosensitive member is worn by such a member being pressed against the surface of the photosensitive member, and the life of the photosensitive member is shortened. Further, from the standpoint of the apparatus, the apparatus is inevitably enlarged to provide such cleaning equipment, which has become a bottleneck when aiming to make the apparatus compact. Furthermore, there has been a demand for a system without waste toner in terms of effective use of toner and reduction of waste.
[0050]
Disclosure of a technique called conventional simultaneous cleaning or cleanerless focuses on positive memory, negative memory, and the like due to the influence of residual toner on an image as disclosed in Japanese Patent Laid-Open No. 5-2287. there were. However, with the progress of the use of electrophotography, there is a need to transfer toner images to various transfer materials, and in this sense, the various transfer properties are not satisfactory.
[0051]
JP-A-59-133573, JP-A-62-203182, JP-A-63-133179, JP-A-64-20587 are disclosed in which technologies related to cleanerless are disclosed. There are JP-A-2-302277, JP-A-5-2289, JP-A-5-53482, JP-A-5-61383, etc., but a desirable image forming method is not described, and the toner configuration Was also not mentioned.
[0052]
Furthermore, in the simultaneous development cleaning that essentially does not have a cleaning device, it is essential to rub the surface of the photosensitive member with toner and a toner carrier. For this reason, toner deterioration due to long-term use, toner carrier surface deterioration, photosensitive Deterioration of durability characteristics remains as a problem because it causes deterioration of the body surface or wear, and the prior art has not been able to solve the problem sufficiently, and it has been desired to achieve both fixing properties and durability characteristics. In addition, in response to higher speeds and higher durability, charging control of the residual toner before collection to improve the recoverability of the residual toner during development is controlled, and development stability is maintained when the collected toner is reused. In terms of the above, the prior art does not provide a sufficient solution.
[0053]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner in which fog on the photoreceptor is stably reduced without impairing fluidity, long-term storage, environmental resistance, and durability.
[0054]
Another object of the present invention is to provide a toner that achieves higher speed, smaller size, and longer life of a machine.
[0055]
Furthermore, an object of the present invention is to form an electrostatic latent image on the photosensitive member, and in the developing process of the electrostatic latent image, the surface of the photosensitive member and the toner layer on the toner carrier are brought into contact with the photosensitive member. In addition, a technology for improving toner deterioration in an image forming method using a contact one-component developing method in which development of an electrostatic latent image is achieved by moving the surface of the photosensitive member and the surface of the toner carrying member relative to each other. It is to be disclosed.
[0056]
Another object of the present invention is to disclose a technique for improving toner carrier surface deterioration.
[0057]
It is another object of the present invention to provide an image forming method that does not cause a cleaning failure even in blade cleaning.
[0058]
A further object of the present invention is to provide an image forming method capable of speeding up the apparatus.
[0059]
It is a further object of the present invention to provide an image forming method that improves both the fixing property and the offset resistance, and at the same time has the durability to stably realize a high-quality image over a long period of time.
[0060]
A further object of the present invention is to provide an image forming method capable of obtaining a stable image over a long period of time without causing defective charging even in a charging method using a contact charging member.
[0061]
Furthermore, an object of the present invention is to provide an image forming method essentially having no cleaning device.
[0062]
Furthermore, an object of the present invention is to provide an extremely good transfer property to various transfer materials such as cardboard and overhead projector transparent film in an image forming method using the simultaneous development cleaning configuration. An object of the present invention is to provide an image forming method capable of designing a system with a wide margin of process.
[0063]
Furthermore, an object of the present invention is to provide an image forming method having durability that smoothly collects transfer residual toner during development and stably realizes a high-quality image over a long period of time by stable development performance.
[0064]
Furthermore, an object of the present invention is to provide an image forming method that is excellent in transferability, has little transfer residual toner, and does not cause transfer loss even in the contact transfer method, or in which these phenomena are suppressed.
[0065]
[Means and Actions for Solving the Problems]
  The present invention relates to a charging step of charging an image carrier for carrying an electrostatic latent image by bringing a charging member to which a voltage is applied from the outside into contact; and electrostatic latent image by image exposure on the charged image carrier An exposure step for developing the electrostatic latent image with a toner included in a developing device to form a toner image; and a transfer step for transferring the toner image formed on the surface of the image carrier onto a transfer material. And an image forming method using a simultaneous development cleaning method in which the developing device also serves to collect toner remaining on the surface of the image carrier after the transfer step in the developing step.Leave
  The toner was produced by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer, carbon black, and an azo-based iron complex compound represented by the following general formula (1) in an aqueous medium. Toner particles, 0.01 to 3.0 wt% polymer fine particles and 0.1 to 3.0 wt% inorganic fine powder based on the toner particles.Toner,
  The toner particles have at least carbon black dispersed in a binder resin, and have a SF-1 value of 100 ≦ SF-1 ≦ 120 with respect to a shape factor measured by an image analyzer, and The value of SF-2 is 100 ≦ SF-2 ≦ 115,
  In the toner, the content A [wt%] of carbon black and the content B [wt%] of the azo-based iron complex compound satisfy the following conditions.
2 ≦ A / B ≦ 35
It is characterized by satisfyingImage forming methodAbout.
[0066]
[Formula 4]

[Where X₁And X₂Represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group and a halogen atom, and X₁And X₂Are the same or different, m and m 'represent an integer of 1 to 3, and R₁And R_ThreeIs a hydrogen atom, C₁~ C₁₈Alkyl group of₂~ C₁₈Alkenyl group, sulfonamide group, mesyl group, sulfonic acid group, carboxyester group, hydroxy group, C₁~ C₁₈A member selected from the group consisting of an alkoxy group, an acetylamino group, a benzoylamino group, and a halogen atom, and R₁And R_ThreeAre the same or different, n and n 'represent an integer of 1 to 3, and R₂And R_FourIndicates a hydrogen atom or a nitro group, and A⁺Represents a cation ion selected from the group consisting of ammonium ion, hydrogen ion, sodium ion, potassium ion and mixed ions thereof. ]
[0069]
According to the present invention, the toner has a shape factor SF-1 value measured by an image analyzer of 100 ≦ SF-1 ≦ 120 and an SF-2 value of 100 ≦ SF-2 ≦ 115, Using a specific azo-based iron complex compound as a toner composition, 0.01 to 3.0% by weight of polymer fine particles with respect to toner particles, and 0.1 to 3.0% by weight of inorganic fine powder with respect to toner particles With toner having a body, it is possible to obtain high-quality image quality due to rapid rise of toner charging and stable cleaning properties. Further, it is possible to stably reduce fog on the photoreceptor without impairing fluidity, long-term storage, environmental resistance, and durability.
[0070]
In addition, according to the present invention, by applying the toner in the present invention to the configuration of one-component contact development, high-quality image quality due to rapid rise of toner charging and stable cleaning can be achieved in the non-magnetic one-component development method. It is possible to get sex.
[0071]
Furthermore, according to the present invention, by applying the toner in the present invention to the configuration for simultaneous development cleaning, charging inhibition of the image carrier due to the transfer residual toner is suppressed, and further, the transfer residual toner is recovered at the time of development. It is possible to achieve both fixing performance and durability performance over a long period of time.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
As a result of intensive studies, the present inventors have combined a specific charge control agent, inorganic fine particles, and polymer fine particles, and can give a specific shape to the toner, thereby responding to higher speed and longer life of the machine. In addition, the present inventors have found that a toner having specifically reduced fog on the photoreceptor (particularly in a low humidity environment) can be obtained without impairing fluidity, long-term storage, environmental resistance, and durability. In addition, this effect is remarkable in the toner manufactured by performing the step of pre-dispersing the specific carbon black and the specific azo-based iron complex compound in the present invention when applied to the polymerization method toner in the present invention. I found out.
[0073]
That is, as described above, the method using the inorganic fine powder and the polymer fine particles together causes a phenomenon in which the toner adheres to the non-latent image forming portion of the photoconductor in a trace amount as the development speed increases (on the photoconductor). (Fog) is a problem. The toner adhering to the non-latent image forming portion is difficult to be transferred in the transfer process, and in the process having the cleaning process, the amount of waste toner is increased or the cleaning is defective. This is disadvantageous in collecting the untransferred toner in development, and causes image defects due to poor charging and poor collection.
[0074]
In addition, a toner in which a specific azo-based iron complex compound is added to a toner having a specific shape and polymer fine particles are added has high image quality due to a rapid rise in toner charging, The charge amount of the developing toner can be appropriately controlled to prevent the cleaning property from being deteriorated due to excessive charging of the transfer residual toner. Furthermore, the toner containing the specific carbon black can increase the charge of the toner more quickly and obtain high quality image quality.
[0075]
In addition, in the simultaneous development recovery process, the charge control characteristics when the toner passes through the charging member is improved, and the charging inhibition of the photoreceptor due to the transfer residual toner is sufficiently suppressed, and the transfer residual toner can be recovered smoothly during development. However, in order to obtain good transferability and image quality, it is essential to add an inorganic fine powder as a fluidity-imparting agent. However, the inorganic fine powder is embedded in the toner surface along with long-term use, thereby causing a change in toner chargeability, transferability due to a decrease in fluidity, and deterioration in image quality.
[0076]
By adding inorganic fine powder and polymer fine particles to toner particles containing a specific azo-based iron complex compound to give the toner a specific shape, the inorganic fine powder can be embedded in the toner surface even after long-term use. Therefore, it is possible to stably obtain excellent transferability and imageability without any change in toner charging property and decrease in fluidity.
[0077]
At the same time, the inventors of the present invention include a specific azo-based iron complex compound, a polymer fine particle added thereto, and a toner having a specific shape has a rapid rise in toner charge, and imparts a one-component charge. In the process, it was found that proper and sufficient tribo application was performed with a low load, and fogging on the photoreceptor was reduced.
[0078]
The mechanism is not necessarily clear, but is presumed as follows.
[0079]
That is, the polymer fine particles usually form flocculates by collecting several tens to thousands of primary fine particles. Aggregates of polymer fine particles have a primary particle shape that is spherical or nearly spherical, and a high bulk density with respect to toner particles, so that an effective share can be applied even in a step of uniformly mixing with toner particles. Since this is not possible, there are many cases in which those that do not collapse preferably remain.
[0080]
In this mixing step, the aggregates of polymer fine particles that have not broken down collapse when frictionally charged in the development step, and contact with the toner in the vicinity at that time, so the electrostatic characteristics of the toner particles change, and the toner It is considered that the distribution of the charging characteristics of the toner spreads and fogging occurs on the photoreceptor.
[0081]
Therefore, by using a specific azo-based iron complex compound, the charge amount of the toner is appropriately controlled, and the effect of preventing excessive charging is promoted, and the dispersion of the polymer fine particles in the mixing process is promoted. It is considered that the occurrence of fog on the photoreceptor is also reduced by the effect of suppressing the change in toner charging property due to electrostatic fixation.
[0082]
In the present invention, the inorganic fine powder needs to be contained at a ratio of 0.1 to 3.0% by weight with respect to the toner particles. A more preferable content is 0.8 to 2.5% by weight. If the content is less than 0.1% by weight, the effect of imparting fluidity to the toner and assisting in charging are not sufficient, and if it exceeds 3.0% by weight, the fixing property of the toner is inhibited. Further, the content of 0.8% by weight or more is advantageous for obtaining charging uniformity on the toner surface, and the content of 0.5% by weight or less is more desirable for low-temperature fixing of the toner. .
[0083]
The inorganic fine powder preferably has a particle size of 1/10 or less of the weight average diameter of the toner particles. The particle size of the inorganic fine powder means the average particle size obtained by observing the surface of the toner particles with an electron microscope. As inorganic fine powder, the following are used, for example. Metal oxide (aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, zinc oxide, etc.), nitride (silicon nitride, etc.), carbide (silicon carbide, etc.), metal salt ( Calcium sulfate, barium sulfate, calcium carbonate, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), carbon black, and silica.
[0084]
In particular, at least one kind is preferably selected from silica, alumina, titania, or a double oxide thereof in order to improve charging stability, developability, fluidity, and storage stability. For example, such silica can be used both as a so-called dry method produced by vapor phase oxidation of silicon halide or alkoxide or dry silica called fumed silica, and so-called wet silica produced from alkoxide water glass. There are few silanol groups on the surface and in the silica fine powder, and Na₂O, SO_Three ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0085]
Furthermore, the inorganic fine powder has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²Those in the / g range give good results. In addition, the inorganic fine powder is preferably hydrophobized. Silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, and other organic silicon It is also possible and preferable to treat with a treating agent such as a compound or an organic titanium compound, or with various treating agents. In particular, silica, alumina, titania, or double oxides thereof are particularly preferably hydrophobized with silicone oil, various modified silicone oils, or various coupling agents.
[0086]
In order to achieve low consumption and high transfer rate, the inorganic fine powder is more preferably treated with at least silicone oil.
[0087]
Furthermore, it is desirable that the toner surface be coated with inorganic fine powder to reduce the stress from the contact member such as the photosensitive member and the charging member, and the external additive coverage on the toner surface is 5 to 5. It is preferably 99%, more preferably 10 to 99%. Further, by having the inorganic fine powder on the surface of the toner particles, the transfer efficiency can be improved and the transfer and omission of characters and line images can be improved.
[0088]
As for the external additive coverage on the toner surface, 100 toner images were randomly sampled using FE-SEM (S-800) manufactured by Hitachi, Ltd., and the image information was sent to the image analysis device (Luxex 3 manufactured by Nicole) via the interface. ) And analyzed and calculated.
[0089]
In the present invention, the polymer fine particles are required to be contained at a ratio of 0.01 to 3.0% by weight with respect to the toner particles. If the content is less than 0.01% by weight, the effect of reducing the embedding of the inorganic fine powder in the toner is not sufficient, and if it exceeds 3.0% by weight, the fixability of the toner is inhibited.
[0090]
The polymer fine particles preferably have an average primary particle size of 0.1 to 3.0 μm. Further, the particle diameter is preferably 1/10 or less of the weight average diameter of the toner particles. Primary particle size of 50 nm or more (preferably a specific surface area of 30 m for improving transferability and / or cleaning properties²It is also one of preferred modes to further add fine particles close to spherical shape (less than / g). For example, spherical polymethylsilsesquioxane particles, spherical resin particles and the like are preferably used. The particle size of the polymer fine particles means the average particle size obtained by observing the surface of the toner particles with an electron microscope.
[0091]
The polymer fine particles are more preferably those having a polarity opposite to that of the toner particles. Resin fine particles having reverse polarity adhere better to the toner surface than polymer fine particles of the same polarity, and uniform dispersion can be maintained over a long period of time. Furthermore, when the polymer fine particles are present as aggregates, if the polymer fine particles have the same polarity as the toner particles, depending on the size of the aggregates and the charge amount, the chargeability of the toner particles may be inhibited, or In development, the stability of the toner coat on the toner carrier may be inhibited. From these viewpoints, it is desirable that the polymer fine particles have a polarity opposite to that of the toner particles. For this reason, it is desirable that the main monomer constituting the toner and the main monomer constituting the resin fine particles are different.
[0092]
In order to obtain polymer fine particles, a conventionally known method, that is, an emulsion polymerization method or a spray drying method can be used.
[0093]
Preferably, resin fine particles having a glass transition point of 80 ° C. or higher obtained by homopolymerization or copolymerization of monomer components such as styrene, acrylic acid, methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate by an emulsion polymerization method are preferable. Indicates.
[0094]
In addition, it may be crosslinked with a crosslinking agent such as divinylbenzene. In order to adjust the specific electric resistance and tribo charge amount, the resin particle surface does not damage the surface of the photoreceptor, metal, metal oxide, pigment, surface activity It may be treated with an agent or the like. Further, in the toner production method by the suspension polymerization method, it may be formed simultaneously with the toner particles. The resin fine particles are preferably spherical, but the resin fine particles work effectively to prevent the surface of the photoreceptor from being damaged by the silica fine powder and are effectively removed by the cleaning blade. For example, it may be appropriately flattened, or a part thereof may be fixed to the toner particle surface in a flattened form.
[0095]
In the toner of the present invention, other additives within a range that does not substantially adversely affect, for example, a lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder, cerium oxide powder, silicon carbide powder, A small amount can also be used as a polishing agent such as strontium titanate powder, an anti-caking agent, or a conductivity imparting agent such as zinc oxide powder or tin oxide powder.
[0096]
In the present invention, SF-1 and SF-2 indicating the shape factor of the toner particles are 100 toner particle images of 2 μm or more magnified 1000 times using, for example, Hitachi FE-SEM (S-800). Samples are randomly sampled, and the image information is introduced into, for example, an image analysis apparatus (Luzex III) manufactured by Nicole via an interface, analyzed, and the values obtained from the following equations are used as shape coefficients SF-1 and SF-2. It is defined as
[0097]
[Expression 1]

(Where MXLNG is the absolute maximum length of the particle, PERIME is the perimeter of the particle, and AREA is the projected area of the particle)
[0098]
In the case of measuring the shape factor of the toner particles by the above method after externally adding polymer fine particles and inorganic fine powder to the toner particles, the polymer fine particles and inorganic fine powder adhering to the toner particle surface are used. Performs image processing so that it is not included in the image analysis data.
[0099]
The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles.
[0100]
Further, from the viewpoint of improving toner fusion on the toner carrier and contamination of the surface of the charging member when a large number of images are printed, the value of SF-1 is 100 ≦ SF-1 ≦ 120, and SF-2 The value needs to be 100 ≦ SF-2 ≦ 115, more preferably the value of SF-1 is 100 ≦ SF-1 ≦ 115, and the value of SF-2 is 100 ≦ SF-2 ≦ 113. It is preferable that the toner is used in order to improve transferability while maintaining developability.
[0101]
When SF-1 is larger than 120, the effect of reducing the embedding of the fine inorganic particles in the toner of the polymer fine particles is not effectively exhibited, and the addition amount of the polymer fine particles is increased to a sufficient extent. In addition, the charge amount distribution is likely to be broad, and in the simultaneous development and recovery process, contamination of the charging member with toner is promoted, and image defects due to poor charging are likely to occur. Further, if SF-2 is larger than 115, the transfer efficiency of the toner image at the time of transfer from the electrostatic image holding member to the transfer material is lowered, and in the simultaneous development recovery process, contamination of the charging member is promoted, which is not preferable. .
[0102]
The azo-based iron complex compound used in the present invention has a structure represented by the following formula (1).
[0103]
[Chemical formula 5]

[Where X₁And X₂Represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group and a halogen atom, and X₁And X₂Are the same or different, and m and m ′ represent an integer of 1 to 3, and R₁And R_ThreeIs a hydrogen atom, C₁~ C₁₈Alkyl group of₂~ C₁₈Alkenyl group, sulfonamide group, mesyl group, sulfonic acid group, carboxyester group, hydroxy group, C₁~ C₁₈A member selected from the group consisting of an alkoxy group, an acetylamino group, a benzoylamino group and a halogen atom,₁And R_ThreeAre the same or different, n and n 'represent an integer of 1 to 3, and R₂And R_FourIndicates a hydrogen atom or a nitro group, and A⁺Represents a cation ion selected from the group consisting of ammonium ion, hydrogen ion, sodium ion, potassium ion and mixed ions thereof. ]
[0104]
The azo-based iron complex compound is also used as a negative charge control agent. The compound can be synthesized by a known method.
[0105]
Typical examples of the azo-type iron complex compound of the general formula include the following compounds.
[0106]
[Chemical 6]

[0107]
[Chemical 7]

[0108]
In the present invention, it is preferable to use a toner in which carbon black having an average primary particle size of 25 to 80 nm and a specific azo-based iron complex compound are used as a black colorant.
[0109]
When the particle size of the carbon black is smaller than 25 nm, when used in combination with the azo-based iron complex compound in the present invention, the primary particle size is fine, so that sufficient dispersion is difficult to obtain, and the effects of the present invention are obtained. I can't. Furthermore, when a toner is produced by a suspension polymerization method, the toner particle size tends to be coarse and difficult to use.
[0110]
If it is larger than 80 nm, even if it is dispersed well, there is a problem that only a low density image can be obtained or the toner consumption is increased due to insufficient coloring power as a toner.
[0111]
Regarding the particle size of carbon black, it is more preferable that the particle size is 25 to 55 nm. When used in combination with the specific azo-based iron complex compound of the present invention, if the particle size of the carbon black is within this range, the charge polarity and charge amount of the transfer residual toner by the charging member can be controlled more reliably and uniformly. This is also more advantageous in terms of toner charge amount stability and toner coloring power.
[0112]
The average primary particle size of carbon black in the toner in the present invention can be measured by taking a photograph enlarged with a transmission electron microscope.
[0113]
The DBP oil absorption of the carbon black used in the present invention is preferably 40 to 150 ml / 100 g.
[0114]
If the carbon black has a short structure with a DBP oil absorption of less than 40 ml / 100 g, the charge amount of the toner tends to be too low, and if it exceeds 150 ml / 100 g, it is difficult to obtain a fine dispersion of the carbon black due to the strong long structure.
[0115]
The DBP oil absorption is measured in accordance with ASTM method D2414-79.
[0116]
The carbon black used in the present invention has a nitrogen adsorption specific surface area of 100 m.²/ G or less and the volatile content is preferably 2% or less. The carbon black according to the present invention has a smaller specific surface area and a smaller volatile content than the carbon black commonly used in toners.
[0117]
Carbon black having a small specific surface area and a small amount of volatile matter has the advantage of low polymerization inhibition because it has few polymerization-inhibiting functional groups, and is also advantageous for uniform dispersion of carbon black in the polymerized toner.
[0118]
Regarding the nitrogen adsorption specific surface area of carbon black, 100m²When it exceeds / g, polymerization inhibition tends to occur. Carbon black having a volatile content of more than 2% is not preferable because a large number of polymerization-inhibiting functional groups exist on the surface.
[0119]
The nitrogen adsorption specific surface area is measured according to ASTM method D3037-78.
[0120]
The volatile content of carbon black is measured in accordance with “JIS K 6221-1982”.
[0121]
Further, when the toner is produced by a polymerization method, it is desirable to perform a step of pre-dispersing the carbon black and the azo iron complex compound according to the present invention in a polymerizable monomer. Since carbon black can be dispersed at a higher concentration, shearing force is easily applied, and the effect of improving dispersibility is increased.
[0122]
FIG. 3 shows changes in viscosity when carbon black and an azo-based iron complex compound according to the present invention are dispersed in styrene. As is apparent from the figure, the addition of the azo-based iron complex compound dramatically increases the viscosity of the dispersion liquid, indicating that carbon black is stably dispersed with high shearing force.
[0123]
Further, in FIG. 4, in carbon black having a particle size of 25 to 80 nm, the relationship between the oil absorption of carbon black and the viscosity of the dispersion when a certain amount of azo-based iron complex compound is added and dispersed in the styrene monomer. Show. From this figure, it is shown that carbon black having a high oil absorption of 40 ml / 100 g or more has a higher viscosity of the dispersion and better dispersibility. However, when the oil absorption of carbon black exceeds 150 ml / 100 g, the viscosity of the dispersion becomes too high, and the granulation property during polymerization tends to be impaired.
[0124]
According to the study by the present inventors, the content A [wt%] of the carbon black with respect to the weight of the toner particles and the azo-based iron complex compound B [wt%] satisfy the following conditions.
2 ≦ A / B ≦ 35
It is preferable to satisfy.
[0125]
If the content of the azo-based iron complex compound is too small relative to the content of carbon black, the viscosity does not increase as is apparent from FIG. 3, and the carbon black is not stably dispersed. In this case, carbon black precipitates with the passage of time, and when a toner is produced using this dispersion, the coloring power does not increase. If the content of the azo-based iron complex compound is too large relative to the carbon black content, the azo-based iron complex causes secondary agglomeration, dispersibility is reduced, polymerization is inhibited, and toner particles are manufactured well. Difficult to do.
[0126]
In the present invention, the carbon black content in the toner particles is preferably 0.1 to 30% by weight, more preferably 1 to 20% by weight. When the carbon black content is less than 0.1% by weight, the coloring power of the toner is low, and when it exceeds 30% by weight, the dispersibility is not sufficiently uniform.
[0127]
In the present invention, the content of the azo-based iron complex compound is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight. If the content of the azo-based iron complex compound is less than 0.01% by weight, it is difficult to increase the viscosity of the dispersion, and even if the content exceeds 20% by weight, the viscosity of the dispersion is lowered and the dispersibility of carbon black is improved. The effect is not enough.
[0128]
In the present invention, when the toner is formed by a polymerization method, the carbon black and the azo iron complex compound are predispersed in the polymerizable monomer to be used, thereby improving the dispersibility of the carbon black. Is remarkable. This is because the dispersion liquid has a high viscosity in order to disperse at a higher concentration, and the dispersion is performed with a high share.
[0129]
As described above, the present inventors can transfer carbon black with a specific azo-based iron complex compound in combination with a specific azo-based iron complex compound having an appropriate structure in a specific oil absorption range, a small specific surface area, and a small volatile content. It has been found that the toner can be improved in charge control characteristics when the toner passes through the charging member.
[0130]
By applying the toner thus obtained, the presence ratio of the excessively charged toner particles or the reversely charged excessively charged particles in the transfer residual toner is reduced, and the cleaning property is improved. Also in the simultaneous development cleaning and cleanerless image forming method of a higher process speed system, when the toner passes through the photosensitive member charging member, the toner polarity is controlled more reliably and uniformly, so that the development can be performed. Shows stable recoverability and stably realizes high-quality images without adversely affecting the development characteristics even when a part of the toner is recovered as a residual toner after development and reused for development. be able to.
[0131]
Further, in order to faithfully develop finer latent image dots for higher image quality, the toner particles preferably have a weight average diameter of 3 μm to 9 μm. For toner particles having a weight average diameter of less than 3 μm, there is a large amount of toner remaining on the photosensitive member or intermediate transfer member due to a decrease in transfer efficiency, and moreover, it tends to cause non-uniform image unevenness due to fog and transfer failure. It is not preferable for the toner used in the present invention. Further, when the weight average diameter of the toner particles exceeds 9 μm, the characters and the line image are likely to be scattered.
[0132]
For the average particle size and particle size distribution of the toner, a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co., Ltd.) is used. And 1% NaCl aqueous solution is prepared using 1st grade sodium chloride as the electrolyte. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample was suspended was subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the volume and number of toners of 2 μm or more were measured using the Coulter counter TA-II with a 100 μm aperture as an aperture. Volume distribution and number distribution were calculated. Then, the volume-based weight average particle diameter (D4) obtained from the volume distribution according to the present invention and the number-based number average particle diameter (Dl) obtained from the number distribution were obtained.
[0133]
In order to improve the toner fixing property and offset resistance, it is preferable to add a release agent to the toner particles. The release agent is preferably a compound having a main endothermic maximum peak value (melting point) in a DSC curve measured in accordance with ASTM D3418-8 in the range of 30 to 120 ° C. (more preferably 40 to 90 ° C.). When the maximum peak value (melting point) of the release agent is less than 30 ° C., the self-aggregation force of the release agent becomes weak, and as a result, the high temperature offset resistance becomes weak. On the other hand, if the maximum peak value exceeds 120 ° C., the fixing temperature becomes high, and it becomes difficult to appropriately smooth the surface of the fixed image, which is not preferable from the viewpoint of color mixing deterioration. Furthermore, when toner particles are obtained by a direct polymerization method, granulation and polymerization are performed in an aqueous medium, and therefore, if the temperature of the endothermic maximum peak value is high, a release agent is mainly precipitated during granulation. Absent.
[0134]
For example, DSC-7 manufactured by Perkin Elmer is used to measure the temperature (melting point) of the maximum peak value of the release agent. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. For the sample, an aluminum pan is used and an empty pan is set as a control, and the temperature is measured from 20 ° C. to 180 ° C. at a heating rate of 10 ° C./min.
[0135]
Release agents include polymethylene waxes such as paraffin wax, polyolefin wax, and Fischer tropish wax, amide waxes, higher fatty acids, higher fatty acid metal salts, long chain alkyl alcohols, ester waxes and derivatives thereof (for example, grafts thereof). Compound or block compound).
[0136]
The release agent is preferably added to the toner in an amount of 2 to 30% by weight. If the addition is less than 2% by weight, the fixability is not sufficiently improved. If the addition exceeds 30% by weight, the fluidity and chargeability of the toner are often hindered. The toner particles are likely to coalesce, and those having a wide particle size distribution are likely to be generated, which is inappropriate for the present invention.
[0137]
In the present invention, a toner having a core / shell structure in the toner, the shell portion being formed by a polymer synthesized by polymerization, and the core portion being composed of wax as a release agent is used for the image forming method of the present invention. By using the toner, it is possible to prevent deterioration of toner particles and contamination of the image forming apparatus, so that good chargeability is maintained and a toner image excellent in reproducing a latent dot image can be formed over a long period of time. It becomes. Further, since the wax acts efficiently at the time of heat and pressure fixing, the low temperature fixing property and the high temperature offset resistance can be improved.
[0138]
In the present invention, the toner having a core / shell structure is such that the surface of the core portion made of wax as a releasing agent is covered with a shell portion formed by a polymer synthesized by polymerization of a polymerizable monomer. Means toner in the form.
[0139]
In the present invention, the core / shell structure of the toner can be confirmed by observing the cross-sectional layer of the toner particles.
[0140]
As a specific method for observing the tomographic plane of the toner particles, the toner particles are sufficiently dispersed in a room temperature curable epoxy resin and then cured in an atmosphere at 40 ° C. for 2 days. After staining with ruthenium oxide and, if necessary, osmium tetroxide, a flaky sample is cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner particles is observed using a transmission electron microscope (TEM). It is preferable to use a ruthenium tetroxide dyeing method in order to provide contrast between materials by utilizing a slight difference in crystallinity between the wax and the resin constituting the outer shell.
[0141]
In the present invention, the content of the release agent in the toner particles is preferably 2 to 30% by weight, more preferably 2 to 25% by weight.
[0142]
When the content of the release agent is less than 2% by weight, the fixing property is insufficiently improved. When the content exceeds 30% by weight, the toner particles are likely to coalesce during granulation even in the production by the polymerization method. Those having a wide distribution are likely to be generated and are not suitable for the present invention.
[0143]
In the present invention, when a toner having a core / shell structure is produced, it is particularly preferable to add a polar resin to the resin constituting the shell portion because the shell portion encapsulates the core portion with wax as a release agent. preferable.
[0144]
As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin are preferably used.
[0145]
The content of the polar resin in the toner particles is preferably 1 to 20% by weight, more preferably 2 to 16% by weight (based on the weight of the toner particles).
[0146]
When the content of the polar resin is less than 1% by weight, the effect of addition is not sufficiently exhibited. When the content exceeds 20% by weight, the charging characteristics of the toner are often affected. It is not preferable because it tends to lower the chargeability of the toner in the environment.
[0147]
In the present invention, an outermost shell resin layer may be further provided on the toner surface.
[0148]
The glass transition temperature of the outermost shell resin layer is preferably designed to be higher than the glass transition temperature of the outer shell resin layer in order to further improve the blocking resistance, and is preferably crosslinked to such an extent that the fixing property is not impaired. . The outermost shell resin layer preferably contains a polar resin or a charge control agent in order to improve chargeability.
[0149]
The method for providing the outermost shell layer is not particularly limited, and examples thereof include the following methods.
[0150]
1. In the latter half of the polymerization reaction or after completion, if necessary, a polar resin, a charge control agent, and a crosslinking agent are dissolved and dispersed in the reaction system, added to the polymerized particles, adsorbed onto the polymerized particles, and then added with a polymerization initiator for polymerization. Method.
[0151]
2. If necessary, emulsion polymer particles or soap-free polymer particles composed of monomers containing a polar resin, a charge control agent, and a cross-linking agent are added to the reaction system and aggregated on the surface of the polymer particles, and if necessary, fixed by heat. Method.
[0152]
3. A method in which emulsion-polymerized particles or soap-free polymerized particles comprising a monomer containing a polar resin, a charge control agent, and a cross-linking agent are mechanically fixed to the toner particle surface in a dry manner, if necessary.
[0153]
In the present invention, by a polymerization method for producing toner particles by polymerizing a monomer composition containing a wax and a polar resin as a release agent together with a colorant and a polymerizable monomer in an aqueous medium, the wax and When toner particles containing a polar resin are produced, the produced toner particles have a core portion made of wax, a polymer synthesized by polymerization of a polymerizable monomer, and a shell portion made of a polar resin. It has a core / shell structure, and the polar resin is positioned in the outermost shell resin layer of the shell portion.
[0154]
Therefore, in the case of toner particles having such a form, since a polar group exists on the surface of carbon black used as a colorant, carbon black does not enter non-polar wax, and the shell portion Therefore, the coloring power tends to be lower than that of toner particles in which carbon black is uniformly dispersed in the toner particles, and a polar resin is formed in the outermost shell layer of the shell portion. Therefore, since the ratio of carbon black located on the surface portion of the toner particle is reduced, the triboelectric chargeability of the toner tends to be lower than that of the toner particle not containing the polar resin.
[0155]
However, in the present invention, since the toner particles contain carbon black and a specific azo iron compound as described above, the coloring power of the toner is improved by the effect of improving the dispersibility of carbon black by the azo iron compound. It is possible to suppress the decrease in the triboelectric chargeability of the toner by suppressing the decrease and by the effect of improving the dispersibility of carbon black and the high charge control effect of the azo-based iron compound.
[0156]
In the one-component contact development type image forming method of the present invention, since the toner on the toner carrier contacts the surface of the image carrier during development, the durability of the toner and the surface of the toner carrier and the image carrier It is preferable that the toner has anti-fusing property to the surface.
[0157]
Therefore, the toner used in the one-component contact development method is required to have higher mechanical characteristics than the toner used in the one-component non-contact development method and the two-component development method having a toner and a carrier.
[0158]
As the binder resin for the toner used in the present invention, generally used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins, and styrene-butadiene copolymers can be used. In the method of obtaining toner particles by a polymerization method, those monomers are preferably used. Specifically, styrene monomers such as styrene, o (m-, p-)-methylstyrene, m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, ( Meth) propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylic acid ester monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide Is preferably used. These monomers are used singly or appropriately mixed so that the theoretical glass transition temperature (Tg) described in Polymer Handbook 2nd edition-Pl39-192 (John Wiley & Sons) is 40-75 ° C. Used. When the theoretical glass transition temperature is less than 40 ° C., there are problems in terms of storage stability of the toner and durability of the developer, and when it exceeds 75 ° C., the fixing point is increased.
[0159]
The molecular weight of the binder resin is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, the toner was previously extracted with a toluene solvent using a Soxhlet extractor for 20 hours, and then the toluene was distilled off with a rotary evaporator. Further, the release agent was dissolved, but the binder resin was After thoroughly washing with an organic solvent that cannot be dissolved, such as chloroform, a sample obtained by filtering a solution soluble in THF (tetrahydrofuran) with a solvent-resistant membrane filter having a pore diameter of 0.3 μm was added 150C manufactured by Waters. The column structure can be used by connecting A-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko and measuring the molecular weight distribution using a standard polystyrene resin calibration curve. The number average molecular weight (Mn) of the obtained resin component is 5000 to 1000000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2-100. Is preferred for the present invention.
[0160]
The azo-based iron complex compound used in the present invention also has a function as a charge control agent, but another charge control agent may be used in combination. As another charge control agent, a known one can be used, but a charge control agent that has a high charging speed and can stably maintain a constant charge amount is preferable. Furthermore, in the present invention, when toner particles are produced by a polymerization method, a charge control agent having no polymerization inhibitory property and no solubilized product in an aqueous system is particularly preferable.
[0161]
Specific examples of other charge control agents include negative-type salicylic acid, naphthoic acid, dicarboxylic acid or its derivative metal compound, azo pigment or its derivative metal compound, sulfonic acid, and carboxylic acid in the side chain. Molecular type compounds, boron compounds, urea compounds, silicon compounds, calixarene, and the like can be used. As the positive system, nigrosine, triphenylmethane compound, quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, an imidazole compound and the like are preferably used. Another charge control agent is preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the binder resin. However, in the present invention, it is not essential to add another charge control agent, and even in the case of using a non-magnetic one-component blade coating development method, the triboelectric charge with the blade member or sleeve member is positively used in the toner. It is not always necessary to include another charge control agent.
[0162]
When the toner particles are produced by the polymerization method in the present invention, examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile. Benzoic initiators such as 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; Peroxide-based polymerization initiators such as peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used.
[0163]
The addition amount of the polymerization initiator varies depending on the desired degree of polymerization, but generally 0.5 to 20% by weight is added to the monomer. The kind of the initiator is slightly different depending on the polymerization method, but can be used alone or mixed with reference to the 10-hour half life temperature.
[0164]
In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like can be further added and used.
[0165]
When suspension polymerization is used as the toner production method according to the present invention, examples of the dispersant used include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, and carbonate as inorganic oxides. Examples thereof include magnesium, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic substance, and ferrite. As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like are used dispersed in an aqueous phase. These dispersants are preferably used in an amount of 0.2 to 10.0 parts by weight with respect to 100 parts by weight of the polymerizable monomer.
[0166]
As these dispersants, commercially available ones may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, the inorganic compound may be generated and used in a dispersion medium under high-speed stirring. I can do it. For example, in the case of tricalcium phosphate, a preferred dispersant for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring. Moreover, you may use together 0.001-0.1 weight part surfactant for refinement | miniaturization of these dispersing agents. Specifically, commercially available nonionic, anionic and cationic surfactants can be used, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, olein. Acid calcium or the like is preferably used.
[0167]
When the polymerization method is used in the toner manufacturing method according to the present invention, the toner can be specifically manufactured by the following manufacturing method. Monomer that is uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc., with a release agent, colorant, charge control agent, polymerization initiator or other additive consisting of a low softening point substance in the monomer. The composition is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and time so that droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving durability characteristics in the image forming method of the present invention, in order to remove unreacted polymerizable monomers, by-products, etc., the latter half of the reaction, Alternatively, a part of the aqueous medium may be distilled off after completion of the reaction. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system.
[0168]
A known method is used for producing the toner in the present invention. For example, as a method for producing the toner of the present invention, a resin, an azo-based iron complex compound, carbon black, a release agent, or the like is pressurized. After uniformly dispersing using a kneader, extruder, or media disperser, collide with the target under mechanical or jet air flow, finely pulverize to the desired toner particle size, and further through a classification process, the particle size distribution A toner production method by so-called pulverization method for sharpening and forming a toner, a method for obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945, and JP-B-36. No. 10231, JP-A-59-53856, and JP-A-59-61842 can be used to directly produce toner. A dispersion polymerization method in which an aqueous organic solvent which is soluble in the polymerizable monomer and insoluble in the obtained polymer is used, or a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator. The toner can be produced using an emulsion polymerization method represented by a soap-free polymerization method.
[0169]
Further, the present invention is particularly effectively used in an image forming apparatus in which the surface of the photoreceptor is an organic compound. That is, when the organic compound forms the surface layer of the photoconductor, it has better adhesion to the binder resin contained in the toner particles than other photoconductors using inorganic materials, and transferability is further reduced. This is because they tend to.
[0170]
Examples of the surface material of the photoreceptor according to the present invention include, but are not limited to, silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. In other words, other monomers or copolymers and blends between the aforementioned binder resins can also be used.
[0171]
In the present invention, it is preferable to impart releasability to the surface of the photoconductor, and the contact angle of water on the surface of the photoconductor is preferably 85 degrees or more. More preferably, the contact angle of the photoreceptor surface with water is 90 degrees or more. A high contact angle on the surface of the photoconductor indicates that the surface of the photoconductor has a high releasability. This effect can significantly reduce the amount of toner remaining on the transfer, greatly increasing the load on the cleaning process. When the toner in the present invention is used, it is possible to more reliably prevent the occurrence of defective cleaning.
[0172]
Also in the simultaneous development recovery process, the amount of residual toner can be remarkably reduced, there is almost no light shielding by the residual toner, and a negative ghost image can be essentially prevented, and in the development area of the residual toner during development. This improves the recovery efficiency of the image and prevents the ghost image.
[0173]
Here, the generation mechanism of the ghost image will be described.
[0174]
The problem of light shielding by the transfer residual toner is particularly problematic when the surface of the photoreceptor is repeatedly used for one transfer material, that is, when the length of the entire circumference of the photoreceptor is shorter than the length of the transfer material in the traveling direction, Since the transfer residual toner must be charged, exposed and developed in the state where the residual toner is present on the photosensitive member, the potential on the surface of the photosensitive member where the residual toner is present does not drop sufficiently and the development contrast becomes insufficient. As for development, it appears on the image as a negative ghost having a lower density than the surroundings.
[0175]
On the other hand, if the cleaning effect of the transfer residual toner is insufficient at the time of development, the toner is developed on the surface of the photoconductor where the transfer residual toner is present, so that the density is higher than the surroundings, and ghost ghosts are generated.
[0176]
With the configuration of the present invention, the ghost image described above can be essentially prevented.
[0177]
When using an organic compound on the surface of the photoreceptor, for example, when a protective film mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or as a charge transport layer of a function-separated organic photoreceptor In addition, when a surface layer having a charge transport material and a resin is provided, a protective layer as described above may be further provided thereon. As a means for imparting releasability to such a surface layer,
(1) Use a resin having a low surface energy as the resin itself constituting the film.
(2) Add additives that impart water repellency and lipophilicity.
(3) Disperse the material having high releasability in powder form.
Etc. (1) is achieved by introducing a fluorine-containing group, a silicone-containing group or the like into the resin structure. As (2), a surfactant or the like may be added as an additive. (3) includes the use of a compound containing a fluorine atom, that is, a compound containing a fluorine atom such as polytetrafluoroethylene, polyvinylidene fluoride, or carbon fluoride.
[0178]
By these means, the contact angle with respect to water on the surface of the photoreceptor can be set to 85 degrees or more. If it is less than 85 degrees, the toner and the toner carrier are likely to deteriorate due to durability.
[0179]
Of these, fluorine-containing resins such as polytetrafluoroethylene and polyvinylidene fluoride are particularly suitable. In the present invention, when the fluorine-containing resin (3) is used as a releasable powder, the dispersion to the outermost layer is preferable.
[0180]
In order to contain these powders on the surface, a layer in which the powder is dispersed in a binder resin is provided on the outermost surface of the photoreceptor, or an organic photoreceptor that is originally composed mainly of a resin. For example, the powder may be dispersed in the outermost surface layer without providing a new surface layer.
[0181]
The amount of the powder added to the surface layer is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, based on the total weight of the surface layer. If the amount is less than 1% by weight, the residual toner is not sufficiently reduced, the cleaning efficiency of the residual toner is not sufficient, and the ghost prevention effect is insufficient. If the amount exceeds 60% by weight, the strength of the film decreases. This is not preferable because the amount of light incident on the photosensitive member is significantly reduced. The particle diameter of the powder is 1 μm or less, preferably 0.5 μm or less from the viewpoint of image quality. When it is larger than 1 μm, the line breakage is deteriorated due to scattering of incident light, and it cannot be put into practical use.
[0182]
As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent for these resins may be used alone or in combination of two or more.
[0183]
Moreover, you may disperse | distribute electroconductive fine particles in resin of a protective layer. Examples of the conductive fine particles include metals and metal oxides, preferably zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide coated titanium oxide, tin coated indium oxide, There are ultrafine particles such as antimony-coated tin oxide and zirconium oxide. These may be used alone or in combination of two or more. In general, when particles are dispersed in a protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of incident light in order to prevent scattering of incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The conductive and insulating particles preferably have a particle size of 0.5 μm or less. Moreover, 2 to 90 weight% is preferable with respect to the protective layer total weight, and, as for content in a protective layer, 5 to 80 weight% is more preferable. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.
[0184]
The surface layer can be applied by spray coating, beam coating or penetration (dipping) coating of the resin dispersion.
[0185]
A preferred development process condition used in the present invention is that the toner layer on the toner carrier and the surface of the photoreceptor are in contact with each other.
[0186]
In the case of a one-component developer, a method in which an elastic roller is used as a toner carrier and a toner layer formed by coating toner on the surface of the elastic roller is brought into contact with the surface of the photoreceptor. At this time, it is important that the toner layer is in contact with the surface of the photoreceptor, regardless of whether the toner is magnetic or non-magnetic. Further, the toner carrier is substantially in contact with the surface of the photoreceptor, which means that the toner carrier is in contact with the photoreceptor when the toner layer is removed from the toner carrier. . At this time, in order to obtain an image having no edge effect by the electric field acting between the photosensitive member and the elastic roller facing the surface of the photosensitive member via the toner layer, the surface of the elastic roller or the vicinity of the surface has a potential, and the photosensitive member There is a need to have an electric field between the surface and the toner carrying surface. Therefore, it is possible to use a method in which the elastic rubber of the elastic roller is resistance-controlled in the middle resistance region to keep the electric field while preventing conduction with the surface of the photoreceptor, or a method of providing a thin insulating layer on the surface layer of the conductive roller. . Furthermore, a conductive resin sleeve in which the side facing the surface of the photoreceptor is covered with an insulating material on the conductive roller, or a conductive layer is provided on the side not facing the photoreceptor with the insulating sleeve is also possible. Further, a configuration in which a rigid roller is used as the toner carrying member and the photosensitive member is flexible such as a belt is possible. The electric resistance of the developing roller as the toner carrier is 10²-10⁹A range of Ω · cm is preferred.
[0187]
When the one-component contact development method is used, the surface of the developing roller carrying the toner may be rotated in the same direction as the peripheral speed of the photosensitive member, or may be rotated in the opposite direction. When the rotation is in the same direction, it is desirable that the peripheral speed ratio is faster than 100% with respect to the peripheral speed of the photoreceptor. If it is 100% or less, the image quality is poor. The higher the peripheral speed ratio, the more toner is supplied to the development site, the more frequently the toner is desorbed from the latent image, and the unnecessary parts are scraped off and applied to the necessary parts. Thus, an image faithful to the latent image can be obtained. Specifically, the moving speed of the toner carrying member surface is preferably 1.05 to 3.0 times the moving speed of the photosensitive member surface.
[0188]
As the cleaning member used in the present invention, a blade, a roller, a fur brush, a magnetic brush, or the like can be used. Two or more of these cleaning members may be used in combination.
[0189]
In the image forming method by the one-component contact development, it is possible to prevent the cleaning property from being deteriorated due to excessive charging of the transfer residual toner by appropriately controlling the charge amount of the developing toner on the photoreceptor.
[0190]
That is, if the transfer residual toner is excessively charged, the adhesion of the transfer residual toner to the photosensitive member is high, so that the cleaning property tends to deteriorate. In particular, when the shape of the toner particles is almost spherical, such as a toner prepared by a polymerization method such as a suspension polymerization method, cleaning is performed in terms of a decrease in scraping property in the cleaning process and ease of slipping through the cleaning member. This is disadvantageous, and excessive charging of the transfer residual toner significantly reduces the cleaning property.
[0191]
The charge of the toner remaining after the transfer varies greatly depending on the transfer bias condition, the resistance of the transfer material, and the like. In general, a voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer bias. However, when the development is normal development (the toner charging polarity and the photosensitive member charging polarity are reversed), the transfer material is a thick paper, an OHT film, or the like. If the toner has a high resistance, toner particles having a high charge are not transferred due to a strong adhesion to the photosensitive member, and the charge proceeds to the cleaning process as it is, and the toner particles are not easily cleaned.
[0192]
Therefore, as the toner, it is desirable that the development toner on the photoconductor is appropriately controlled in the charge amount, and the toner having a high charge amount is not originally developed on the photoconductor.
[0193]
Further, in the contact development method, since the toner layer and the surface of the photosensitive member are in contact with each other, charging of the toner due to friction with the photosensitive member occurs, and charging due to friction with the photosensitive member is little in charging of the developing toner. It turned out that it affected. According to the study by the present inventors, the value of the shape factor SF-1 measured by the toner image analyzer is 100 <SF-1 ≦ 160, and the value of SF-2 is 100 <SF-2 ≦ 140. In this case, the toner is uniformly charged by friction with the photoconductor, and the toner of high charge amount is difficult to be developed on the photoconductor, whereas the value of SF-1 is SF-1> 160. Or if the value of SF-2 is SF-2> 140, the toner is not uniformly charged due to friction with the photosensitive member, the toner charge variation becomes large, and the high charge amount It was found that a large amount of toner was generated and a part of the toner was developed to the photosensitive member.
[0194]
Further, according to the study by the present inventors, when the polymer fine particles added to the toner in the present invention have charging properties, the toner can be charged by friction with the surface of the photoreceptor in the contact development method based on the toner shape. It has been found that this is greatly affected.
[0195]
That is, the chargeability of the polymer fine particles is advantageous from the viewpoint of the adhesion of the polymer fine particles, but the polarity opposite to that of the toner particles is advantageous. When released from the process to the end of the transfer process, the polymer fine particles adhere to the surface of the photoreceptor with a very high charge amount, which causes a significant decrease in cleaning properties.
[0196]
In addition, when the polymer fine particles have the same polarity as the toner, the free polymer fine particles themselves have a large specific charge due to the small particle size, which inhibits uniform charging of the toner particles, and developability / transferability. Is greatly reduced. Such release of the polymer fine particles from the toner particles is greatly facilitated by the rubbing between the surface of the photoreceptor and the toner layer, and the release of the polymer fine particles from the toner particles and the toner shape are reduced. It has been found by the present inventors that it is closely related.
[0197]
When the value of the toner shape factor SF-1 is 100 ≦ SF-1 ≦ 120 and the value of SF-2 is 100 ≦ SF-2 ≦ 115, the release of the polymer fine particles from the toner particles is suppressed. However, the effect of reducing the embedding of fine polymer particles into the toner of the polymer fine particles is effectively exhibited, and the toner is uniformly charged by rubbing with the photosensitive member, so that the charging property is stable over a long period of time. The toner shown is obtained.
[0198]
When the toner particle surface has irregularities, the polymer particles are less likely to be liberated, but in view of the effect of reducing embedding in the inorganic fine powder in the toner particles, toner particles with smaller contact opportunities and charging opportunities. Even if the embedding of the inorganic fine particles in the concave portion is reduced, the effect of maintaining the chargeability and fluidity as the toner particles is small.
[0199]
As a whole toner, the adhesion and release of polymer fine particles are easy even in the toner particle convex part having a larger contact opportunity between the toner particles, the charge imparting member, the toner carrying member, the toner layer thickness regulating member, and the photosensitive member. Significantly affects chargeability.
[0200]
When the convex portions of the toner particles are smoother, the polymer fine particles are less likely to be separated from the toner particles, and when the toner shape factor SF-1 is greater than 120 or SF-2 is greater than 115. In the contact development method in which the toner particles are excessively subjected to large stress due to rubbing with the photoreceptor, the polymer fine particles are easily released at the toner particle convex portions, and it is difficult to obtain stable toner chargeability.
[0201]
Even in the development simultaneous cleaning process, the release of the polymer fine particles from the toner particles leads to contamination of the charging member with the polymer fine particles, which significantly impairs the uniform charging of the photosensitive member by the charging member or reduces the developability. Adversely affect.
[0202]
Therefore, in the simultaneous development cleaning process, the toner shape factor needs to be 100 ≦ SF-1 ≦ 120 for SF-1 and 100 ≦ SF-2 ≦ 115 for SF-2.
[0203]
Further, in order to prevent development of high charge amount toner on the photosensitive member, it is necessary to impart charge to the toner or to suppress toner chargeability. However, if the toner is not sufficiently charged, fogging, toner scattering, and transferability decrease. It is easy to cause harmful effects such as. By using the toner of the present invention, it is possible to suppress generation of excessively charged toner particles and to give the toner an appropriate charge amount. As a result, stable performance excellent in durability is exhibited even in the development process.
[0204]
In addition, when the development is reversal development (the toner charging polarity and the photosensitive member charging polarity are the same polarity), if the transfer material is easy to pass an electric field like thin paper, a toner that is strongly charged to the reverse polarity by the transfer bias can be produced, After all, it has a strong adhesion to the photoconductor and cannot easily be cleaned.
[0205]
On the other hand, by using the toner of the present invention, it is possible to suppress the generation of toner particles charged to an excessively reverse polarity and to control the toner charging by the transfer bias.
[0206]
Although these reasons are not necessarily clear, the polymer fine particles used in the toner of the present invention and a specific azo-based iron complex compound prevent the toner from having an abnormally high charge amount (so-called charge-up phenomenon). As a result, even if a reverse electric field is applied to the polarity of the toner during the transfer process, the toner has an excessive reverse charge that is difficult to hold, and it can be stably present on the toner surface even when used in combination with polymer particles. It is considered that the effect of the inorganic fine powder, and the effect of suppressing the toner charging variation due to the frictional charging with the photoreceptor by using the toner having a specific shape.
[0207]
One of the preferable image forming methods used in the present invention is to have a step of collecting the toner remaining on the photoreceptor after the transfer step in the development step.
[0208]
First, the principle of the simultaneous development cleaning method or the cleanerless image forming method will be described.
[0209]
The principle is that the charge polarity and charge amount of the toner on the photosensitive member in each electrophotographic process are controlled and the reversal development method is used.
[0210]
For example, when a negatively charged photoconductor and a negatively charged toner are used, in the transfer process, an image visualized by a positive polarity transfer member is transferred to a transfer material. Depending on the relationship between the type of transfer material (difference in thickness, resistance, dielectric constant, etc.) and the image area, the charge polarity of the residual toner varies from positive to negative. However, the negatively charged charging member for charging the negatively chargeable photoconductor causes the surface of the photoconductor and even the residual toner to be transferred to the negative side even if the toner remains in the positive polarity in the transfer process. Charge polarity can be made uniform. Therefore, when reversal development is used as the developing method, the toner remaining in the transfer is left negatively charged in the bright portion potential portion where the toner is to be developed, and the dark portion potential where the toner is not to be developed is Due to the development electric field, the toner is attracted toward the toner carrying member, and the toner does not remain on the photosensitive member having the dark portion potential.
[0211]
However, when image formation is performed at a higher process speed, the toner remaining uniformly on the surface of the photosensitive member is also transferred to the surface of the photosensitive member by the charging member in correlation with the decrease in the charging time per unit surface area of the photosensitive member. It becomes difficult to make the charging polarity uniform. Therefore, when reversal development is used as a developing method, it becomes difficult for the transfer residual toner on the dark portion potential that should not be developed by the toner to be attracted toward the toner carrier by the developing electric field and collected. Even if the toner carrier is recovered by mechanical force such as rubbing, if the charge of the residual toner is not uniform, the chargeability of the toner on the toner carrier will be adversely affected, and the development characteristics Reduce. Also, charging failure due to contamination of the charging member is likely to occur.
[0212]
By controlling the charging polarity of the residual toner at the same time as the charging of the photosensitive member, a simultaneous development cleaning and a cleanerless image forming method are established.
[0213]
In order to improve the recoverability of the transfer residual toner during development, the charge polarity control must be performed more quickly, and in order to maintain the development performance, the transfer residual toner is more surely and uniform when passing through the charging member. The charging polarity must be controlled.
[0214]
In particular, in the so-called contact charging method in which charging is performed by bringing the charging member into contact with the photosensitive member, the charging member is in contact with the photosensitive member when the discharge according to the so-called Paschen's law is used as the charging mechanism. In addition, adhesion to the charging member is also deteriorated due to toner deterioration due to discharge energy.
[0215]
Conventionally, a transfer residual toner is cleaned from the photosensitive member by a cleaning member such as a blade or a fur brush, and the toner existing on the photosensitive member is charged, collected by the developing device, and this toner is used as the developing device. No consideration has been given to the effect on development performance when it is collected and reused.
[0216]
The present inventors diligently studied various toners. As a result, in the simultaneous development cleaning and the cleanerless image forming method, the toner passes through the charging member by using a specific inorganic fine powder and organic resin fine particle and a specific azo-based iron complex compound. The charge control characteristics at the time are improved, and these durability characteristics and image quality characteristics are closely related.
[0217]
The contact transfer process applicable to the image forming method of the present invention will be specifically described below.
[0218]
In the contact transfer process, the developed image is electrostatically transferred to the transfer material while the transfer unit is brought into contact with the surface of the photosensitive member via the transfer material. The pressure is preferably 2.9 N / m (3 g / cm) or more, more preferably 9.8 to 490 N / m (10 to 500 g / cm). If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because transfer of the transfer material and transfer failure are likely to occur. When the contact pressure is too high, the photoreceptor is deteriorated and toner is fused to the surface of the photoreceptor.
[0219]
In addition, as a transfer means in the contact transfer process, an apparatus having a transfer roller or a transfer belt is used. The transfer roller has at least a core metal and a conductive elastic layer covering the core metal, and the conductive elastic layer has a volume resistance of 10 such as urethane or EPDM in which conductive fine particles such as carbon are dispersed.⁶-10^TenIt is made of an elastic body of about Ωcm.
[0220]
The present invention is particularly effective for an image forming apparatus having a small drum-shaped photosensitive member having a diameter of 50 mm or less. That is, in the case of a small-diameter photosensitive drum, pressure concentration tends to occur at the contact portion of the contact member with the same linear pressure. Although the belt photoreceptor is considered to have the same phenomenon, the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the contact portion.
[0221]
Furthermore, in the present invention, it is desirable to control the total charge amount of the toner when developing the toner, and the surface of the toner carrier according to the present invention is coated with a resin layer in which conductive fine particles and / or lubricant are dispersed. Preferably it is.
[0222]
As a charging method, a known corona charging method called corotron or scorotron is used, and a method using a pin electrode can also be used. The contact charging method can also be used in the same manner.
[0223]
The present invention is particularly effective in the case of the contact charging method in which the charging means abuts the charging member on the surface of the photoreceptor. That is, compared to non-contact corona discharge in which the charging means does not contact the surface of the photoconductor, the contact charging method is liable to cause deterioration of the surface of the photoconductor. This is because the increase is in the direction of severe cleaning. Therefore, the effect of high transferability of the present invention becomes more remarkable.
[0224]
As a preferable process condition when a charging roller is used as the contact charging member, the contact pressure of the charging roller is 4.9 to 490 N / m (5 to 500 g / cm), and the polarity of the transfer residual toner is charged to the photoreceptor. In order to make the polarity the same as the polarity and to facilitate recovery at the time of development, it is preferable to apply a DC voltage, but when using a DC voltage superimposed with an AC voltage, 2 × Vth (V) [Vth; DC It is preferable to superimpose an AC voltage having a peak-to-peak voltage less than the discharge start voltage (V) in application on the DC voltage.
[0225]
Other contact charging members include a method using a charging blade and a method using a conductive brush. These contact charging means are effective in that a high voltage is not required and generation of ozone is reduced.
[0226]
As the contact charging member, in the case of a roller or a blade, a conductive metal such as iron, copper, and stainless steel, a carbon dispersion resin, a metal, or a metal oxide dispersion resin is used as a conductive substrate. As the shape, a rod shape, a plate shape or the like can be used. For example, as the configuration of the elastic roller, a structure in which an elastic layer, a conductive layer, and a resistance layer are provided on a conductive substrate is used. The roller elastic layer includes chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber, sponge such as rubber foam or foam of rubber, styrene-butadiene thermoplastic elastomer, polyurethane thermoplastic elastomer, polyester. It can be formed from a thermoplastic elastomer such as a thermoplastic elastomer or an ethylene-vinegar thermoplastic elastomer. The conductive layer has a volume resistivity of 10⁷It is preferable to be Ω · cm or less.⁶More preferably, it is Ω · cm or less. For example, metal vapor deposition film, conductive particle dispersion resin, conductive resin, etc. are used. Specific examples include metal vapor deposition films such as aluminum, indium, nickel, copper, iron, carbon, aluminum, nickel, titanium oxide, etc. Conductive particles dispersed in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, polymethyl methacrylate, and the like, and quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl Examples thereof include conductive resins such as aniline, polyvinyl pyrrole, polydiacetylene, and polyethyleneimine. For example, the resistive layer has a volume resistivity of 10⁶-10¹²A layer of Ω · cm is preferable, and a semiconductive resin, a conductive particle-dispersed insulating resin, or the like can be used. Examples of the semiconductive resin include ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymer nylon, polyvinyl hydrin, and casein. Examples of conductive particle-dispersed resins include small amounts of conductive particles such as carbon, aluminum, indium oxide, and titanium oxide in insulating resins such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethyl methacrylate. Examples include dispersed ones.
[0227]
As the brush as the contact charging member, a brush whose resistance is adjusted by dispersing a conductive material in commonly used fibers is used. As the fiber, generally known fiber can be used, and examples thereof include nylon, acrylic, rayon, polycarbonate, polyester and the like. As the conductive material, generally known conductive materials can be used, and metals such as copper, nickel, iron, aluminum, gold, silver, or iron oxide, zinc oxide, tin oxide, antimony oxide, titanium oxide, etc. Examples thereof include conductive powders such as metal oxides and carbon black. These conductive materials may be subjected to surface treatment for the purpose of hydrophobization and resistance adjustment as necessary. In use, it is selected in consideration of dispersibility with fibers and productivity. As the shape of the brush, the fiber thickness is 1 to 20 denier (fiber diameter of about 10 to 500 μm), the brush fiber length is 1 to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1 1.5 x 10 per square meter⁷~ 4.5 × 10⁸About this) is preferably used.
[0228]
【Example】
Hereinafter, the present invention will be described in more detail with specific methods for manufacturing toners and photosensitive drums, examples, and comparative examples.
[0229]
Carbon black shown in Table 1 was prepared.
[0230]
[Table 1]

[0231]
Using these carbon blacks, a pre-dispersion liquid having a composition as shown in Table 2 was prepared. The formulations shown in Table 2 were stirred and dispersed with a media disperser for 3 hours, and the viscosity of the dispersion after the pre-dispersion treatment was measured.
[0232]
[Table 2]

[0233]
Using the above pre-dispersion liquid, toner particles were prepared by combining the formulations shown in Table 3. At this time, the ratio of carbon black contained was set constant.
[0234]
As the polyester resin, a polyester resin having a peak molecular weight of 6000 and an acid value of 10 to 20 obtained by condensing propoxylated bisphenol and terephthalic acid was used.
[0235]
[Table 3]

[0236]
Examples of toner production are shown below.
[0237]
[Production Example A of Polymerized Toner]
To 700 g of ion-exchanged water in a 2-liter four-necked flask, 0. lM-Na_ThreePO_Four500 g of an aqueous solution was added and heated to 60 ° C., and then stirred at 12000 rpm using a high-speed stirring device TK type homomixer (manufactured by Tokushu Kika Kogyo). To this, 1.0M-CaCl₂76 g of an aqueous solution was gradually added to obtain an aqueous medium containing a minute hardly water-soluble dispersion stabilizer.
[0238]
On the other hand, as a pre-dispersion process
(Monomer) Styrene 2000g
(Colorant) Carbon Black a 160g
(Dispersion aid / charge control agent) Azo-based iron complex compound (1) 40 g
The prescription was stirred for 3 hours with a media disperser and predispersed. When the viscosity of the dispersion after the pre-dispersion treatment was measured, it had a viscosity of 460 centipoise. Furthermore, as a dispersoid,

The above formulation was heated to 60 ° C., uniformly dissolved and dispersed. Into this, 10 g of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
[0239]
The polymerizable monomer composition is charged into the aqueous medium, and 65 ° C., N₂Under an atmosphere, the mixture was stirred at 12000 rpm for 10 minutes with a TK homomixer to granulate the polymerizable monomer composition. Thereafter, while stirring with a paddle stirring blade (100 rpm), the reaction was performed at the same temperature for 5 hours, and then the temperature was raised to 80 ° C. and the reaction was further performed for 5 hours. After completion of the polymerization reaction, the remaining monomer is distilled off under reduced pressure, and after cooling, hydrochloric acid is added to dissolve calcium phosphate, followed by filtration, washing with water, and drying, sharp black suspension particles having a weight average diameter of about 6.7 μm. (Toner particles) were obtained.
[0240]
With respect to 100 parts by weight of the obtained toner particles, 1.5 parts by weight of the hydrophobic silica (a) shown in Table 4 as the inorganic fine powder and 0.1% of the polymethyl methacrylate fine particles (h) shown in Table 5 as the polymer fine particles. 2 parts by weight were externally added to obtain a polymerized toner A. The obtained polymerization toner A was randomly sampled with 100 toner images of 2 μm or more magnified 1000 times using an FE-SEM (S-800) manufactured by Hitachi, Ltd., and the sample was collected in an image analyzer (Luzex III) manufactured by Nicole. When the shape factor was calculated by introducing the sample and analyzing it, the shape factor of the toner particles was 117 for SF-1 and 115 for SF-2.
[0241]
[Production Examples B to D of Polymerized Toner]
0.1M-Na_ThreePO_FourAqueous solution and 1.0M-CaCl₂By adjusting the amount of the aqueous solution, the addition amount of the saturated polyester of the polar resin to be added, and the acid value, toners having different shape factors SF-1 and SF-2 were prepared in the same manner as in [Polymerized toner production example A]. -D was produced. Table 6 shows the physical properties of the toner thus obtained.
[0242]
[Comparative Production Examples E and F of Polymerized Toner]
0.1M-Na_ThreePO_FourAqueous solution and 1.0M-CaCl₂By adjusting the amount of the aqueous solution, the pH of the aqueous medium at the time of granulation, the addition amount of the saturated polyester of the polar resin to be added, and the acid value, toners having different shape factors SF-1 and SF-2 can be produced [manufacturing the polymerized toner]. Polymerized toners E and F were prepared in the same manner as in Example A]. Table 6 shows the physical properties of the toner thus obtained.
[0243]
[Production Examples G and H of Polymerized Toner]
0. lM-Na_ThreePO_FourAqueous solution and 1.0M-CaCl₂Polymerized toners G and H were prepared in the same manner as in [Polymerized toner production example A] by adjusting the amount of aqueous solution. Table 6 shows the physical properties of the toner thus obtained.
[0244]
[Production Example I of Polymerized Toner]
A pre-dispersion No. using carbon black b shown in Table 1 instead of carbon black a. 2 except that 1.2 parts by weight of hydrophobic silica (b) as an inorganic fine powder and 0.1 parts by weight of polymethyl methacrylate fine particles (j) having a particle diameter of 0.15 μm as polymer fine particles were externally added. Polymerized toner I was produced in the same manner as in [Polymerized toner production example A]. In addition, Table 6 shows the physical properties of the obtained toner.
[0245]
[Production Examples J to M of Polymerized Toner]
The previous dispersion No. 1 in which the addition amount of the azo-based iron complex compound (1) was changed was used. Polymerized toners J to M were produced in the same manner as in [Polymerized toner production example I] except that 3 to 6 were used. Table 6 shows the physical properties of the toner thus obtained.
[0246]
[Comparative Production Example N of Polymerized Toner N]
A pre-dispersion No. containing no azo-based iron complex compound was added. Polymerized toner N was prepared in the same manner as in [Polymerized toner production example I] except that No. 7 was used. Table 6 shows the physical properties of the toner thus obtained.
[0247]
[Production Examples O to X of Polymerized Toner]
Carbon black c to l are used in place of carbon black a, 1.0 part by weight of hydrophobic silica (d) as an inorganic fine powder, and polymethyl methacrylate fine particles (k) 0 having a particle diameter of 0.4 μm as polymer fine particles Polymerized toners O to X were prepared in the same manner as in [Polymerized toner production example A] except that 1 part by weight was externally added. However, the polymerization toner W using carbon black k could not be obtained as a toner because the pre-dispersion was non-uniform and could not be granulated. Table 6 shows the physical properties of the toner thus obtained.
[0248]
[Table 4]

[0249]
[Table 5]

[0250]
[Table 6]

[0251]
(Photoreceptor Production Example 1)
As a photoreceptor, a 30φ, 254 mm aluminum cylinder was used as a base. Then, layers having the following constitutions were sequentially laminated by dip coating to produce a photoreceptor.
[0252]
(1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powders dispersed in a phenolic resin. Film thickness 15 μm.
[0253]
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
[0254]
(3) Charge generation layer: Mainly composed of an azo pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
[0255]
(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by the Ostwald viscosity method) at a weight ratio of 8:10, and polytetrafluoroethylene powder ( 10% by weight with respect to the total solid content was added and dispersed uniformly. Film thickness 25 μm.
[0256]
The contact angle of water on the surface of the obtained photoreceptor with respect to water was 95 degrees.
[0257]
The contact angle was measured using pure water, and the device used was Kyowa Interface Science Co., Ltd., contact angle meter CA-DS type.
[0258]
(Photoreceptor Production Example 2)
A charge transport layer having a film thickness of 25 μm was formed in the same manner as in Photoconductor Production Example 1 except that no polytetrafluoroethylene powder (particle size 0.2 μm) was added to the charge transport layer, and a photoconductor was produced. did. The contact angle of water on the surface of the obtained photoreceptor with respect to water was 79 degrees.
[0259]
<Example 1>
A 600 dpi laser beam printer (manufactured by Canon: LBP-830) was prepared as an image forming apparatus. This apparatus was modified to print 16 sheets per minute with A4 size paper at a process speed of 80 mm / s (variable toner carrier speed). As shown in FIG. 1, this apparatus uses a roller 32 to which direct current and alternating current components are applied to uniformly charge the photosensitive member 26 (30φ). A process of forming an electrostatic latent image by exposing the image portion with laser light 20 after charging, forming a visible image with toner 33, and then transferring the toner image to transfer material 28 with transfer roller 27 to which voltage is applied. have. The toner image on the transfer material is fixed by a heat and pressure fixing unit 31 having a heat roller and a pressure roller.
[0260]
The cleaning blade is removed, and a transfer simultaneous cleaning system in which the toner remaining after transfer is collected in the developing device at the same time as the development is provided.
[0261]
Next, the developer container 22 in the process cartridge was modified. Instead of an aluminum sleeve containing a magnet as a toner supply body, a medium resistance rubber roller (16φ) made of silicone rubber in which carbon black is dispersed and the resistance is adjusted is used as a toner carrier 24 and is in contact with the photoreceptor 26. The rotation peripheral speed of the toner carrier is the same in the contact portion with the photosensitive member, and is driven to be 150% of the peripheral rotation speed of the photosensitive member. That is, the peripheral speed of the toner carrier is 120 mm. / S and the relative speed with respect to the surface of the photoreceptor is 40 mm / s.
[0262]
As a means for applying the toner to the toner carrier, an application roller 25 is provided at the developing portion and brought into contact with the toner carrier. The toner was applied onto the toner carrier by rotating in the opposite direction to the toner carrier at the contact portion. Further, a stainless steel blade 23 coated with resin was attached to control the coat layer of the toner on the toner carrier.
[0263]
The photoreceptor was (Photoreceptor Production Example 1), the toner was Toner A, and the process conditions were set to satisfy the following development conditions.
[0264]
Photoconductor dark area potential (V_D-700V
Photoreceptor bright area potential (V_L-150V
Development bias (V_DC-400V (DC component only)
[0265]
In the reversal development method, as a preferable development condition for carrying out the simultaneous development cleaning, the dark portion potential (V_D) And light potential (V_L) And a DC bias (V) applied to the toner carrier._DC)_D-V_DC｜ ＞ ｜ V_L-V_DCIt is better to set so that the relationship | More preferably | V_D-V_DCThe value of | is | V_L-V_DCIt is better to be at least 10V larger than the value of |
[0266]
When a continuous image output test of 1000 sheets of a 4% character A4 print ratio was performed and image evaluation was performed, the image density, fogging suppression on the photoreceptor, and transferability were good, and an image quality equivalent to the initial one was obtained. . As a transfer material, 75 g / m²Paper was used. Further, although both the photoconductor and the developing roller were observed, it was not necessary to replace them without fusing. Further, the SEM observation of the toner surface revealed that the inorganic fine powder and polymer fine particles on the toner surface were compared with the initial toner before the toner container was filled even with the toner in the vicinity of the toner carrier after the continuous image of 1000 sheets. Little change was seen in the appearance.
[0267]
In the present invention, the evaluation of splattering is a splattering evaluation with fine fine lines related to the image quality of a graphical image, and is a splattering evaluation with one dot line that is more likely to scatter than splattering with character lines.
[0268]
Further, the resolving power was evaluated by the reproducibility of a 600 dpi 50 μm small-diameter isolated dot as shown in FIG.
[0269]
Transferability is the transfer residual toner on the solid black photoconductor, and fog is the tape transfer residual toner on the solid white photoconductor. It was evaluated by a numerical value obtained by subtracting the Macbeth concentration of the sample with only the paste. Therefore, the smaller the value, the better the transferability and fog suppression.
[0270]
Also, the stain due to poor charging of the 100th image was evaluated. The image density and image smear were also evaluated after printing 1000 sheets of characters with a printing ratio of 4%. Furthermore, the charging roller unit surface area (cm²) Toner adhesion amount (mg) was measured.
[0271]
Image dirt
A: Not generated
○: Slightly occurring but practical
△: Less generated but not practical
×: Remarkably generated and not practical
Evaluation based on the criteria. That is, all the images were made unusable except for image stains that would not be understood unless observed well.
[0272]
The contamination of the charging roller is caused by the toner weight per unit area on the charging roller (mg / cm²) Was measured.
[0273]
Transferability, fog, image density, and resolving power were evaluated in the same manner as in Example 1.
[0274]
As a result, as shown in Table 7, a high-quality image with high density and no image contamination was obtained.
[0275]
<Example 2>
The same procedure as in Example 1 was performed except for the following.
[0276]
The toner carrying member was driven so that the rotational peripheral speed of the toner carrying member was in the same direction at the contact portion with the photosensitive member and was 200% with respect to the photosensitive member rotational peripheral speed. The peripheral speed of the toner carrier is 160 mm / s, and the relative speed with respect to the surface of the photoreceptor is 80 mm / s.
[0277]
Toner B was used as the toner, and process conditions were set so as to satisfy the following development conditions.
[0278]
Development bias -500V (DC component only)
[0279]
A durability test of 1000 sheets was performed while replenishing the toner, but the image density, fog suppression, and transferability were good, and no poor cleaning occurred, and an image quality equivalent to the initial one was obtained. Further, although both the photoconductor and the developing roller were observed, it was not necessary to replace them without fusing. Table 7 shows the evaluation results.
[0280]
<Examples 3 to 5>
Evaluation was performed in the same manner as in Example 1 except that polymerized toners B to D were used as toners. As shown in Table 7, the results were generally good.
[0281]
<Comparative Examples 1 and 2>
A similar test was performed in Example 1 except that the polymerization toners E and F and the photoreceptor of photoreceptor preparation example 2 were used.
[0282]
Process conditions were set to satisfy the following development conditions.
[0283]
Development bias -350V (DC component only)
[0284]
In the case of the polymerization toner E, a remarkable image defect due to a remarkable charging failure occurred at 100 sheets. With the polymer toner F, fog was slightly increased on the 100th sheet, and a remarkable image defect due to a charging failure occurred on the 1000th sheet.
[0285]
In addition, both the superposed toners E and F were insufficiently reproduced as isolated dots of 50 μm, and the line image was conspicuous.
[0286]
The results are shown in Table 7.
[0287]
[Table 7]

[0288]
<Examples 6 to 11>
As the toner, polymerized toners G to H are used, and polymerized toners Ga to Gc and Ha to Hc in which inorganic fine powders and organic fine particles to be added are shown in Table 8 are used in the same manner as in Example 1. evaluated. As a result, as shown in Table 10, generally good results were obtained.
[0289]
<Comparative Example 3>
Evaluation was performed in the same manner as in Example 1 except that polymerized toner G based on polymerized toner G was used, as shown in Table 8, except that polymerized toner Gd to which inorganic fine powder was not added was used. As shown in Table 10, the fog suppression was worse than the initial 100 sheets, the transferability was not good, and the image was stained due to contamination of the charging member.
[0290]
[Table 8]

[0291]
<Examples 12 to 19>
Evaluation was performed in the same manner as in Example 1 except that polymerized toner I based on polymerized toner I and polymerized toners Ia to Ij having inorganic fine powder and organic fine particles added as shown in Table 9 were used. As a result, as shown in Table 10, generally good results were obtained.
[0292]
<Comparative example 4>
Evaluation was performed in the same manner as in Example 1 except that the polymerized toner I was used based on the polymerized toner I and the polymerized toner Ik to which no organic fine particles were added as shown in Table 9. As shown in Table 10, the transferability was slightly worse than the initial 100 sheets, and after 1000 sheets, image smearing occurred due to contamination of the charging member.
[0293]
[Table 9]

[0294]
[Table 10]

[0295]
  <Example 22Reference Example 1, Examples 24 and 25, Reference Example 2>
  Evaluation was performed in the same manner as in Example 1 except that polymerized toners I to M were used as toners. As a result, as shown in Table 11, generally good results were obtained.
[0296]
<Comparative Example 5>
Evaluation was conducted in the same manner as in Example 1 except that the polymerized toner N was used as the toner. As a result, as shown in Table 11, fog suppression was poor, noticeable image staining due to poor cleaning occurred, and the image density was low.
[0297]
<Examples 27 to 35>
Evaluation was conducted in the same manner as in Example 1 except that polymerized toners O to V and X were used as toners. As shown in Table 11, generally good results were obtained for the polymerized toners O to U. However, in the polymerized toner V, the image density was slightly low at the initial stage, and the image density gradually increased. Stable. With the polymerization toner X, the image density was slightly low.
[0298]
[Table 11]

[0299]
  <Reference example 3>
  As shown schematically in FIG. 5, the image forming apparatus is configured such that the cleaning member is attached to the image forming apparatus used in Example 1, and the transfer residual toner is scraped off from the surface of the photosensitive member by the cleaning member and recovered as waste toner. A device was prepared.
[0300]
Evaluation was performed in the same manner as in Example 1 except that the polymer toner Ia used in Example 12 was used as the toner, and the degree of image contamination due to defective cleaning was used as an evaluation item instead of evaluation of image contamination due to defective charging. As a result, as shown in Table 12, a good image was obtained up to the 1000th sheet without causing a cleaning failure.
[0301]
Further, SEM observation of the toner surface of the toner near the toner carrier after continuous image printing of 5000 sheets showed that the state of the inorganic fine powder and organic fine particles on the toner surface compared to the initial toner before filling the toner container. Little change was seen.
[0302]
  <Comparative Example 6>
  Other than using the polymerized toner Ik used in Comparative Example 4 as the tonerReference example 3And evaluated in the same manner. The results are shown in Table 12,Reference example 3Transferability was inferior to that of the first sheet, and the 1000th sheet had slight image stains due to poor cleaning, and the fog suppression was also deteriorated.
[0303]
  <Reference example 4>
  Except for using the polymerization toner A used in Example 1 as the toner,Reference example 3And evaluated in the same manner. As a result, as shown in Table 12, a good image was obtained up to the 1000th sheet without causing a cleaning failure.
[0304]
  <Comparative Example 7>
  As the toner, except that the polymerization toner E used in Comparative Example 1 is used.Reference example 3And evaluated in the same manner. The results are shown in Table 12,Reference example 4Transferability was inferior to that of No. 1, and, on the 1000th sheet, spot-like fogging that was thought to be caused by slipping of polymer fine particles from the cleaning member was generated, transferability was further reduced, and image contamination due to poor cleaning occurred.
[0305]
[Table 12]

[0306]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain high-quality image quality and transferability due to rapid rise of toner charging, which can cope with higher speed and longer life of the machine. Further, the fog on the photoreceptor can be stably reduced without impairing fluidity, long-term storage, environmental resistance, and durability.
[0307]
Furthermore, according to the present invention, by applying the toner of the present invention to the configuration of the simultaneous development cleaning, the charge amount of the developing toner on the photoreceptor is appropriately controlled, and the development caused by the adverse effects of the transfer residual toner and fog toner It is possible to prevent the deterioration of the cleaning performance in the process, and at the same time, to achieve both the fixing performance and the durability performance over a long period of time.
[0308]
Further, even in contact one-component development, excellent development characteristics can be obtained due to good charge controllability on the toner carrying member in which excessive charging is suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an image forming method using a simultaneous development cleaning system, which is used as an example of an image forming method according to the present invention.
FIG. 2 is an explanatory diagram of a circular spot pattern for evaluating resolution.
FIG. 3 is a graph showing changes in viscosity when carbon black and an azo-based iron complex compound according to the present invention are dispersed in styrene.
FIG. 4 is a graph showing the relationship between the amount of oil absorption and viscosity of carbon black when a certain amount of an azo-based iron complex compound is added and dispersed in styrene in the carbon black according to the present invention.
FIG. 5 is a schematic diagram illustrating an image forming method using a contact one-component developing device, which is used as an example of an image forming method according to the present invention.
[Explanation of symbols]
22 Developer container
23 Toner regulating blade
24 Toner carrier (elastic roller)
25 Toner application roller
26 Photoconductor (image carrier)
27 Transfer roller
28 Transfer material
30 Bias applying means
31 Fixing device
32 Charging roller
33 Toner

Claims (21)

A charging process in which a charging member to which a voltage is applied from the outside is brought into contact to charge an image carrier for carrying an electrostatic latent image; exposure in which an electrostatic latent image is formed on the charged image carrier by image exposure A developing step of developing the electrostatic latent image with toner included in the developing device to form a toner image; and a transferring step of transferring the toner image formed on the surface of the image carrier onto a transfer material. , Oite and recovery of toner remaining in the image bearing member surface after the transfer process in an image forming method using the cleaning simultaneous with developing system conducted developing device serves in the development step,
The toner was produced by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer, carbon black, and an azo-based iron complex compound represented by the following general formula (1) in an aqueous medium. and the toner particles against the toner particles, a toner for chromatic and 0.01-3.0 wt% of the polymer fine particles and 0.1 to 3.0% by weight of an inorganic fine powder,
The toner particles have at least carbon black dispersed in a binder resin, and have a SF-1 value of 100 ≦ SF-1 ≦ 120 with respect to a shape factor measured by an image analyzer, and The value of SF-2 is 100 ≦ SF-2 ≦ 115,
In the toner, the carbon black content A [wt%] and the azo iron complex compound content B [wt%] satisfy the following condition 2 ≦ A / B ≦ 35.
An image forming method characterized by satisfying the above.

[Wherein, X ₁ and X ₂ represent a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group and a halogen atom, and X ₁ and X ₂ are the same or different, m and m ′ represent an integer of 1 to 3, and R ₁ and R ₃ are a hydrogen atom, a C ₁ -C ₁₈ alkyl group, a C ₂ -C ₁₈ alkenyl group, a sulfonamide group, a mesyl group, a sulfonic acid group, carboxy ester group, hydroxy group, an alkoxy group of C ₁ -C _18, an acetylamino group, displays a member selected from the group consisting of benzoylamino group and a halogen atom, R ₁ and R ₃ are the same or different cage, n and n 'displays an integer of 1 to 3, R ₂ and R ₄ displays a hydrogen atom or a nitro group, a ⁺ is an ammonium ion, hydrogen ion, sodium ion, potassium ion And shows a cation ion selected from the group consisting of mixed ion. ] 2. The image forming method according to claim 1, wherein the polymer fine particles contained in the toner are substantially spherical with a ratio of major axis to minor axis of 1.2 or less. 3. The image forming method according to claim 1, wherein the polymer fine particles contained in the toner have an average primary particle diameter of 0.1 to 3.0 [mu] m. 4. The image forming method according to claim 1, wherein the polymer fine particles contained in the toner have a polarity opposite to that of the toner. 5. The image forming method according to claim 1, further comprising 0.8 to 2.5% by weight of inorganic fine powder based on the toner particles. 6. The image forming method according to claim 1, wherein the inorganic fine powder contained in the toner is hydrophobized. 7. The image forming method according to claim 1, wherein the inorganic fine powder contained in the toner is at least treated with silicone oil. 8. The image forming method according to claim 1, wherein the carbon black has a particle size of 25 to 80 nm. The image forming method according to claim 8, wherein the carbon black has a particle size of 25 to 55 nm. 10. The image forming method according to claim 8, wherein the carbon black has a DBP oil absorption of 40 to 150 ml / 100 g. 11. The image forming method according to claim 8, wherein the carbon black has a nitrogen adsorption specific surface area of 100 m ² / g or less and a volatile content of 2% or less. The toner particles are produced by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer, the carbon black, the azo-based iron compound, a release agent, and a polar resin in an aqueous medium. The image forming method according to claim 1, wherein the image forming method is one . The polymerizable monomer composition is prepared by mixing a dispersion obtained by dispersing the carbon black and the azo-based iron compound in a first polymerizable monomer with at least a second polymerizable monomer. The image forming method according to claim 12, wherein The toner particles contain a wax as a release agent in addition to the binder resin, the carbon black, and the azo-based iron compound, and the toner particles include the core portion of the release agent and the core portion. The image forming method according to claim 1, wherein the image forming method has a core / shell structure having a shell portion having a binder resin that covers the surface thereof. In addition to the binder resin, carbon black, and the azo iron compound, the toner particles have a wax having a maximum endothermic peak in a temperature range of 40 ° C. to 90 ° C. in an endothermic curve by DSC measurement as a release agent. The image forming method according to claim 1, wherein the image forming method is an image forming method . In developing process, the moving speed of the toner carrying member surface at the developing region, one of the claims 1 to 15, characterized in that the speed is set to 1.05 to 3.0 times the moving speed of the photoreceptor surface the image forming method according to any. In the developing step, a toner layer with a regulated toner layer thickness is formed on the surface of the toner carrying member by bringing a toner layer regulating member into contact with the toner carried on the toner carrying member. the image forming method according to any one of claims 1 to 16,. The toner is held in the developing device, according to any one of claims 1 to 17 by the toner supplying member for supplying the toner to the toner carrying member, characterized in that it is supplied to the toner carrying member Image forming method. In the transfer step, the transfer means to which a voltage is applied from the outside when transferring is brought into contact with the image carrier through the transfer material, and the toner image formed on the image carrier is transferred to the transfer material. the image forming method according to any one of claims 1 to 18, characterized in that transferred to. In the charging step, the voltage applied from the outside to the charging member is a DC voltage, or an AC voltage having a peak-to-peak voltage less than 2 × Vth (V) [Vth; the image forming method according to any one of claims 1 to 19, characterized in that superimposed on. The image bearing member is made of an electrophotographic photoreceptor, image forming method according to any one of claims 1 to 20 water contact angle of the photosensitive member surface, characterized in that at least 85 degrees.

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