JP2004333820A - Toner and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner which is hardly affected by the environment, has stable electrostatic charge performance, is high in image density even in long-time use, is suppressed in the occurrence of fogging and is excellent in image reproducibility. <P>SOLUTION: The toner containing the particles obtained by flocculating and associating at least resin particles and iron oxide is characterized by that (1) the C content and Fe content measured by the ESCA analysis method are <0.001, (2) the toner satisfying ≤0.02 in (the minimum distance between the iron oxide and the surface layer of the toner)/(the diameter of the equivalent projected area of the toner) by observation of TEM exits at ≥30number% and (3) sr at 1,000 oersted is 0.6-6.2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１４９】
さらに、本発明に係わる磁性トナーは高い帯電能力を有するために、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好ましい。また、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。
【０１５０】
トナー担持体表面を被覆する樹脂層に含有される導電性微粒子としては、カーボンブラック、グラファイト、導電性酸化亜鉛の如き導電性金属酸化物及び金属複酸化物を単独でもしくは２種類以上組み合わせて用いるのが好ましい。この導電性微粒子及び／又は滑剤が分散される樹脂としては、フェノール系樹脂、エポキシ系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリカーボネート系樹脂、ポリオレフィン系樹脂、シリコーン系樹脂、フッ素系樹脂、スチレン系樹脂、アクリル系樹脂の如き公知の樹脂が用いられる。特に熱硬化性樹脂または光硬化性の樹脂が好ましい。
【０１５１】
また、非接触の現像方法においては、現像工程でトナーを担持して現像部に搬送するトナー担持体の移動速度を、感光体の移動速度に対して速度差をもたせることが好ましい。このような速度差を設けることにより、トナー担持体側から感光体側へトナー粒子を十分に供給することができ、良好な画像を得ることができるためである。
【０１５２】
トナーを担持するトナー担持体表面は、感光体表面の移動方向と同方向に移動していてもよいし、逆方向に移動していてもよい。その際の速度としては、トナー担持体表面と感光体表面の移動速度が等速であるより、一方が他方に対して１．０２〜３．０倍の速度で移動していることが好ましい。
【０１５３】
現像部においては、該磁性トナーを静電潜像に転移させて現像するために交流バイアスが印加されているが、この際の交流バイアスは、少なくともピークトゥーピークの電界強度が３×１０^６〜１×１０^７Ｖ／ｍであり、周波数１００〜５０００Ｈｚであることが好ましい。また、更に直流バイアスを重畳することも好ましい形態である。
【０１５４】
次に帯電工程について説明する。
【０１５５】
本発明においては、コロナ放電を用いた帯電装置を使用する帯電工程の如き非接触の帯電工程でも構わないが、帯電部材を感光体に当接させる接触帯電法が好ましい帯電法である。この場合、接触帯電部材としては、帯電ローラを用いることが好ましい。
【０１５６】
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、ローラーの当接圧が４．９〜４９０Ｎ／ｍ（５〜５００ｇ／ｃｍ）で、直流電圧または直流電圧に交流電圧を重畳したものが用いられる。直流電圧に交流電圧を重畳したものを用いる場合は、交流電圧＝０．５〜５ｋＶｐｐ、交流周波数＝５０〜５ｋＨｚ、直流電圧＝±０．２〜±５ｋＶが好ましい。
【０１５７】
この他の帯電手段としては、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を使用する場合にも、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。
【０１５８】
接触帯電手段としての帯電ローラ及び帯電ブレードの材質としては、導電性ゴムが好ましく、その表面に離型性被膜を設けてもよい。離型性被膜としては、ナイロン系樹脂、ＰＶｄＦ（ポリフッ化ビニリデン）、ＰＶｄＣ（ポリ塩化ビニリデン）、フッ素アクリル樹脂が適用可能である。
【０１５９】
次に転写工程について説明する。
【０１６０】
本発明においては、コロナ放電を用いた転写装置を使用する転写工程の如き非接触の転写工程でも構わないが、好ましくは転写手段を転写材を介して感光体に当接させて転写を行う接触転写方法である。
【０１６１】
転写手段の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１９．６Ｎ／ｍ（２０ｇ／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。
【０１６２】
また、接触転写工程における転写手段としては、転写ローラあるいは転写ベルトを有する装置が使用される。図５に転写ローラの構成の一例を示す。転写ローラ３４は少なくとも芯金３４ａと導電性弾性層３４ｂからなり、導電性弾性層はカーボン等の導電材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おり、転写バイアス電源３５により転写バイアスが印加されている。
【０１６３】
次に、本発明において用いられる感光体について以下に説明する。
【０１６４】
感光体としては、ａ−Ｓｅ、ＣｄＳ、ＺｎＯ２、ＯＰＣ（有機感光体）、ａ−Ｓｉの如き光導電絶縁物質層を持つ感光ドラムもしくは感光ベルトが好適に使用される。
【０１６５】
特に、本発明においては感光体表面が高分子結着剤を主体として構成されている感光体を用いることが好ましい。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（保護層）を設ける場合、または機能分離型の有機感光体の電荷輸送層として電荷輸送材と樹脂からなる表面層を設ける場合、またその表面層の上に樹脂を主体とした保護層を設ける場合等がある。これらの表面層（または保護層）は離型性を有していることが好ましく、実際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させる、
手段などが挙げられる。▲１▼の例としては、樹脂の構成単位の構造中にフッ素含有基、シリコーン含有基の如き官能基を導入することが挙げられる。▲２▼の撥水、親油性を付与するような添加剤としては、例えば、界面活性剤が挙げられる。▲３▼の高い離型性を有する材料としては、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、フッ化カーボンが挙げられる。
【０１６６】
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、トナーの転写性及び感光体の耐久性を一層向上させることができる。感光体表面の水に対する接触角は、９０度以上であることが好ましい。本発明においては、上記▲１▼〜▲３▼の手段の中では、▲３▼のように含フッ素樹脂の離型性粉体の最表面層へ分散させることが好適であり、離型性粉体としてはポリ４フッ化エチレンを使用するのが特に好ましい。
【０１６７】
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離型性粉体を分散させた層を感光体最表面に設けるか、または、感光体自体が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、最上層に離型性粉体を分散させればよい。離型性粉体の添加量は、表面層総量に対して、１〜６０質量％が好ましく、２〜５０質量％が更に好ましい。離型性粉体の添加量が１質量％より少ないとトナーの転写性及び感光体の耐久性改善の効果が不十分であり、６０質量％を越えると保護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。
【０１６８】
本発明においては、帯電手段が帯電部材を感光体に当接させる接触帯電法が好ましい帯電方法であるが、帯電手段が感光体に接することのないコロナ放電等による方法にくらべて感光体表面に対する負荷が大きいので、感光体の表面に保護層（保護膜）を設けることが耐久性に関する改善効果が顕著であり、好ましい適用形態の一つである。
【０１６９】
また、本発明においては、接触帯電方法、接触転写方法を適用することが好ましいため、直径が５０ｍｍ以下の径が小さい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、画像形成において使用する感光体の径が小さい場合には、同一の線圧に対する曲率が大きく、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、本発明は転写部での曲率半径が２５ｍｍ以下の画像形成装置に対しても有効である。
【０１７０】
本発明に用いられる感光体の好ましい様態の一つを以下に説明する。
【０１７１】
導電性基体としては、アルミニウム・ステンレスの如き金属、アルミニウム合金、酸化インジウム−酸化錫合金による被膜層を有するプラスチック、導電性粒子を含侵させた紙、プラスチック、導電性ポリマーを有するプラスチックの円筒状シリンダー及びフィルムが用いられる。
【０１７２】
これら導電性基体上には、感光層の接着性の向上、塗工性の改良、基体の保護、基体上の欠陥の被覆、基体からの電荷注入性の改良、感光層の電気的破壊に対する保護等を目的として下引き層を設けても良い。下引き層は、ポリビニルアルコール、ポリ−Ｎ−ビニルイミダゾール、ポリエチレンオキシド、エチルセルロース、メチルセルロース、ニトロセルロース、エチレン−アクリル酸コポリマー、ポリビニルブチラール、フェノール樹脂、カゼイン、ポリアミド、共重合ナイロン、ニカワ、ゼラチン、ポリウレタン、酸化アルミニウムの如き材料によって形成される。下引き層の膜厚は通常、０．１〜１０μｍであり、好ましくは０．１〜３μｍ程度である。
【０１７３】
電荷発生層は、アゾ系顔料、フタロシアニン系顔料、インジゴ系顔料、ペリレン系顔料、多環キノン系顔料、スクワリリウム色素、ピリリウム塩類、チオピリリウム塩類、トリフェニルメタン系色素、セレン、非晶質シリコンの如き無機物質の様な電荷発生物質を適当な結着剤に分散し塗工するか、または蒸着により形成される。結着剤としては、例えば、ポリカーボネート樹脂、ポリエステル樹脂、ポリビニルブチラール樹脂、ポリスチレン樹脂、アクリル樹脂、メタクリル樹脂、フェノール樹脂、シリコーン樹脂、エポキシ樹脂、酢酸ビニル樹脂が挙げられ、このような広範囲な樹脂から任意に結着剤を選択できる。電荷発生層中に含有される結着剤の量は、電荷発生層全体に対して８０質量％以下が好ましく、０〜６０質量％が更に好ましい。また、電荷発生層の膜厚は５μｍ以下が好ましく、特には０．０５〜２μｍが好ましい。
【０１７４】
電荷輸送層は、電界の存在下で電荷発生層から電荷キャリアを受け取り、これを輸送する機能を有している。電荷輸送層は電荷輸送物質を必要に応じて結着樹脂と共に溶剤中に溶解させ、塗工することによって形成される。電荷発生層の膜厚は一般的には５〜４０μｍである。電荷輸送物質としては、主鎖または側鎖にビフェニレン、アントラセン、ピレン、フェナントレンの如き構造を有する多環芳香族化合物、インドール、カルバゾール、オキサジアゾール、ピラゾリンの如き含窒素環式化合物、ヒドラゾン化合物、スチリル化合物、セレン、セレン−テルル、非晶質シリコン、硫化カドニウムが挙げられる。
【０１７５】
また、これら電荷輸送物質を分散させる結着樹脂としては、ポリカーボネート樹脂、ポリエステル樹脂、ポリメタクリル酸エステル、ポリスチレン樹脂、アクリル樹脂、ポリアミド樹脂の如き樹脂、ポリ−Ｎ−ビニルカルバゾール、ポリビニルアントラセンの如き有機光導電性ポリマーが挙げられる。
【０１７６】
更に、表面層として、更に別途保護層を設けてもよい。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、またはこれらの樹脂の硬化剤を単独または２種以上組み合わせて用いることができる。
【０１７７】
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、酸化ジルコニウムの超微粒子が挙げられる。これらの導電性微粒子は単独で用いてもよいし、２種以上を混合して用いてもよい。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微粒子の粒径は０．３μｍ以下であることが好ましい。また、保護層中での導電性微粒子の含有量は、保護層総重量に対して２〜９０質量％が好ましく、５〜８０質量％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。
【０１７８】
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または浸透（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。
【０１７９】
次に、本発明の画像形成方法を図に沿って具体的に説明する。
【０１８０】
図１の画像形成装置において、１００は感光ドラムで、その周囲に一次帯電ローラー１１７、現像器１４０、転写帯電ローラー１１４、クリーナ１１６、レジスタローラー１２４等が設けられている。そして感光体１００は一次帯電ローラー１１７によって、例えば−７００Ｖに帯電される。（印加電圧は交流電圧−２．０ｋ Ｖｐｐ、直流電圧−７００Ｖｄｃ）そして、レーザー発生装置１２１によりレーザー光１２３を感光体１００に照射することによって露光される。感光体１００上の静電潜像は現像器１４０によって一成分磁性現像剤で現像され、転写材を介して感光体に当接された転写ローラー１１４により転写材上へ転写される。トナー画像をのせた転写材は搬送ベルト１２５等により定着器１２６へ運ばれ転写材上に定着される。また、一部感光体上に残されたトナーはクリーニング手段１１６によりクリーニングされる。現像器１４０は図２に示すように感光体１００に近接してアルミニウム、ステンレスの如き非磁性金属で作られた円筒状のトナー担持体１０２（以下現像スリーブと称す）が配設され、感光体１００と現像スリーブ１０２との間隙は図示されないスリーブ／感光体間隙保持部材等により約３００μｍに維持されている。現像スリーブ内にはマグネットローラー１０４が現像スリーブ１０２と同心的に固定、配設されている。但し現像スリーブ１０２は回転可能である。マグネットローラー１０４には図示のように複数の磁極が具備されており、Ｓ１は現像、Ｎ１はトナーコート量規制、Ｓ２はトナーの取り込み／搬送、Ｎ２はトナーの吹き出し防止に影響している。トナーは、トナー塗布ローラ１４１によって、現像スリーブ１０２に塗布され、付着して搬送される。搬送されるトナー量を規制する部材として、弾性ブレード１０３が配設され弾性ブレード１０３の現像スリーブ１０２に対する当接圧により現像領域に搬送されるトナー量が制御される。現像領域では、感光体１００と現像スリーブ１０２との間に直流及び交流の現像バイアスが印加され、現像スリーブ上現像剤は静電潜像に応じて感光体１００上に飛翔し可視像となる。
【０１８１】
本発明における各種物性データの測定法を以下に詳述する。
【０１８２】
（１）トナー表面に存在する炭素元素の含有量（Ａ）に対する鉄元素の含有量（Ｂ）の比（Ｂ／Ａ）
本発明におけるトナー表面に存在する炭素元素の含有量（Ａ）に対する鉄元素の含有量（Ｂ）の比（Ｂ／Ａ）は、ＥＳＣＡ（Ｘ線光電子分光分析）により表面組成分析を行い算出した。
【０１８３】
本発明では、ＥＳＣＡの装置および測定条件は、下記の通りである。
使用装置：ＰＨＩ社（Ｐｈｙｓｉｃａｌ Ｅｌｅｃｔｒｏｎｉｃｓ Ｉｎｄｕｓｔｒｉｅｓ，Ｉｎｃ．）製 １６００Ｓ型 Ｘ線光電子分光装置
測定条件：Ｘ線源 ＭｇＫα（４００Ｗ）
分光領域８００μｍφ
本発明では、測定された各元素のピーク強度から、ＰＨＩ社提供の相対感度因子を用いて表面原子濃度（原子％）を算出した。
【０１８４】
測定試料としては、トナーを用いるが、トナーに外添剤が添加されている場合には、イソプロパノールの如きトナーを溶解しない溶媒を用いて、トナーを洗浄し、外添剤を取り除いた後に測定を行う。
【０１８５】
（２）トナーの平均円形度
本発明における円形度は、粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明では東亜医用電子社製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて粒子形状の測定を行い、円形度を下記式により求める。更に下式で示すように、測定された全粒子の円形度の総和を全粒子数で除した値を平均円形度と定義する。
【外２】

【０１８６】
なお、本発明で用いている測定装置である「ＦＰＩＡ−１０００」は、各粒子の円形度を算出後、平均円形度の算出に当たって、粒子を得られた円形度によって、円形度０．４００〜１．０００を０．０１０間隔で、０．４００以上０．４１０未満、０．４１０以上０．４２０未満・・・０．９９０以上１．０００未満及び１．０００の如くに６１分割した分割範囲に分け、分割点の中心値と頻度を用いて平均円形度の算出を行う算出法を用いている。
【０１８７】
この算出法で算出される平均円形度の各値と、上述した各粒子の円形度を直接用いる算出式によって算出される平均円形度の各値との誤差は、非常に少なく、実質的には無視できる程度であるため、本発明においては、算出時間の短縮化や算出演算式の簡略化の如きデータの取り扱い上の理由で、上述した各粒子の円形度を直接用いる算出式の概念を利用し、一部変更したこの様な算出法を用いている。
【０１８８】
本発明における円形度は、粒子の凹凸の度合いを示す指標であり、粒子が完全な球形の場合に１．０００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【０１８９】
円形度の具体的な測定方法としては、ノニオン型界面活性剤約０．１ｍｇを溶解している水１０ｍｌにトナー約５ｍｇを分散させ分散液を調整し、超音波（２０ｋＨｚ、５０Ｗ）を分散液に５分間照射し、分散液濃度を５０００〜２００００個／μｌとして、上記フロー式粒子像測定装置を用い、３μｍ以上の円相当径を有する粒子の円形度分布を測定する。
【０１９０】
測定の概略は、東亜医用電子社（株）発行のＦＰＩＡ−１０００のカタログ（１９９５年６月版）、測定装置の操作マニュアル及び特開平８−１３６４３９号公報に記載されているが、以下の通りである。
【０１９１】
試料分散液は、フラットで扁平な透明フローセル（厚み約２００μｍ）の流路（流れ方向に沿って広がっている）を通過させる。フローセルの厚みに対して交差して通過する光路を形成するように、ストロボとＣＣＤカメラが、フローセルに対して、相互に反対側に位置するように装着される。試料分散液が流れている間に、ストロボ光がフローセルを流れている粒子の画像を得るために１／３０秒間隔で照射され、その結果、それぞれの粒子はフローセルに平行な一定範囲を有する２次元画像として撮影される。それぞれの粒子の２次元画像の面積から、同一の面積を有する円の直径を円相当径として算出する。それぞれの粒子の２次元画像の投影面積及び投影像の周囲長から上記の円形度算出式を用いて各粒子の円形度を算出する。
【０１９２】
（３）トナーの粒度分布
測定装置としてはコールターカウンターＴＡ−ＩＩ型（コールター社製）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ＣＸ−１パーソナルコンピュータ（キヤノン製）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。例えば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）を使用できる。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ホン酸塩）を０．１〜５ｍｌ加え、さらに測定試料を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分間分散処理を行い、前記コールターカウンターＴＡ−ＩＩ型により、アパチャーとして１００μｍアパチャーを用いて、トナーの体積、個数を測定して２〜４０μｍの粒子の体積分布と個数分布とを算出する。それから数平均粒径（Ｄ１）体積分布から求めた重量基準の重量平均径Ｄ４（各チャンネルの中央値をチャンネルごとの代表値とする）、体積分布から求めた重量基準の１２．７μｍ以上の重量分布を求める。
【０１９３】
（４）磁性体の疎水化度
なお、本発明における疎水化度とは以下の方法により測定されたものである。磁性体の疎水化度の測定は、メタノール滴定試験により行う。メタノール滴定試験は、疎水化された表面を有する磁性体の疎水化度を確認する実験的試験である。
【０１９４】
メタノールを用いた疎水化度測定は次のように行う。磁性体０．１ｇを容量２５０ｍｌのビーカーの水５０ｍｌに添加する。その後メタノールを液中に徐々に添加し滴定を行う。この際メタノールは液底部より供給し、緩やかに攪拌しながら行う。磁性体の沈降終了は、液面に磁性体の浮遊物が確認されなくなった時点とし、疎水化度は、沈降終了時点に達した際のメタノール及び水混合液中のメタノールの体積百分率としてあらわされる。
【０１９５】
（実施例）
以下、実施例により本発明を詳細に説明するが、本発明を何ら限定するものではない。本発明のトナーは、下記の樹脂微粒子分散液、着色剤分散液、離型剤分散液をそれぞれ調製し、これを所定の割合で混合し攪拌したながら、これに無機金属塩の重合体を添加し、イオン的に中和させて凝集粒子を形成する。無機水酸化物で系内のｐＨを弱酸性から中性に調整した後、前記樹脂微粒子のガラス転移温度以上に加熱して融合・合一温度まで昇温せしめる。融合・合一温度到達後、系内のｐＨを弱酸性から酸性に調整して加熱を継続する。反応終了後、十分な洗浄、固液分離、乾燥の工程を経て所望のトナーを得る。以下、それぞれの調製方法を説明する。なお実施例に記載されている部数または％は、質量部または質量％を示す。
【０１９６】
次に、下記実施例１〜６および比較例１〜４において用いた画像形成装置について説明する。
【０１９７】
非接触の現像方法によって現像を行う市販のレーザービームプリンターＬＢＰ−ＳＸ（キヤノン製）を以下に示す如く改造して用いた。すなわち、プロセスカートリッジ部分のトナー層厚規制部材をウレタンゴム製の弾性ブレードに変え、たＬＢＰプリンターを用いた。
【０１９８】
画出し条件を下記に示す。
【０１９９】
図６は、使用される交番電圧を説明したものである。Ｖｄｃは直流電源電圧を示し、Ｖｄは静電潜像担持体上の暗部電位、ＶＬは明部電位をそれぞれ表す。ｆは交番電圧の周波数、Ｖｐｐは交番電圧のピーク間の電圧を示す。
【０２００】
Ｖｄを−６００Ｖとして静電潜像を形成し、感光ドラム３と現像スリーブ１５上の現像剤層を非接触に間隙（３００μｍ）を設定し、現像スリーブ１５にはバイアス印加手段１２により、交流バイアス（ｆ＝３２００Ｈｚ Ｖｐｐ＝１８００Ｖ）及び直流バイアス（Ｖｄｃ＝−４００Ｖ）とを印加し、ＶＬを−１５０Ｖに設定し画出しを行った。
【０２０１】
また、感光ドラムに対する現像スリーブの周速比を２００％に設定した。
【０２０２】
（樹脂微粒子分散液１の調製）
スチレン ３３０重量部
ｎ ブチルアクリレート ８０重量部
アクリル酸 ６重量部
ジビニルベンゼン ２．３重量部
ドデカンチオール ６重量部
四臭化炭素 ４重量部
前記成分（全体の重量４１２．６ｇ）を混合溶解して溶液を調製し、他方非イオン性界面活性剤（花王社製、ノニポール４００）６ｇ、及びアニオン性界面活性剤（第一工業薬品社製、ネオゲンＳＣ）１０ｇをイオン交換水５５０ｇに溶解し、前記溶液を加えてフラスコ中で分散し乳化して１０分間ゆっくり攪拌・混合しながら、過硫酸アンモニウム５ｇを溶解したイオン交換水５０ｇを投入した。次いで、系内を窒素で十分に置換した後、フラスコを攪拌しながらオイルバスで７０℃まで加熱し、５時間そのまま乳化重合を継続して、中心径１７３ｎｍ、ガラス転移温度５９℃、Ｍｗ ５２，５００の樹脂微粒子を含有するアニオン性樹脂微粒子分散液１を得た。
【０２０３】
１０を得た。
【０２０４】
（磁性体分散液１の調製）
磁性体
（残留磁化４．２Ａｍ^２／ｋｇ、粒径 ０．２μ［０．０３〜０．１μｍ：１５個数％、０．３μｍ以上：２％］）
シランカップリング剤［ｎ−Ｃ_４Ｈ_９Ｓｉ（ＯＣＨ_３）_３］０．２部処理、疎水化度 ２５％） １５０重量部
非イオン性界面活性剤（花王社製、ノニポール４００） １０重量部
イオン交換水 ４００重量部
前記成分を混合溶解し、ホモジナイザー（ＩＫＡ社製、ウルトラタラックス）により１０分間分散し、中心粒径０．２３μの磁性体分散液１を得た。
【０２０５】
（磁性体分散液２の調製）
磁性体として、粒度分布の異なる磁性体
（残留磁化４．１Ａｍ^２／ｋｇ、粒径０．２μ［０．０３〜０．１μｍ：１５個数％、０．３μｍ以上：９％］
シランカップリング剤［ｎ−Ｃ_４Ｈ_９Ｓｉ（ＯＣＨ_３）_３］０．２部処理、疎水化度２３％）
を同量用いた以外は磁性体分散液１の調製と同様にして、中心径は０．２３μの着色剤粒子を含有する磁性体分散液２を得た。
【０２０６】
（磁性体分散液３の調製）
磁性体として、粒度分布の異なる磁性体
（残留磁化４．３Ａｍ^２／ｋｇ、粒径０．２μ［０．０３〜０．１μｍ：３３個数％、０．３μｍ以上：９％］
シランカップリング剤［ｎ−Ｃ_４Ｈ_９Ｓｉ（ＯＣＨ_３）_３］０．２部処理、疎水化度２３％）
を同量用いた以外は磁性体分散液１の調製と同様にして、中心径は０．２３μの着色剤粒子を含有する磁性体分散液３を得た。
【０２０７】
（磁性体分散液４の調製）
磁性体として、疎水化処理を行わない磁性体
（残留磁化４．２Ａｍ^２／ｋｇ、粒径０．２μ［０．０３〜０．１μｍ：１５個数％、０．３μｍ以上：２％］）
を同量用いた以外は磁性体分散液１の調製と同様にして、中心径は０．２５μの着色剤粒子を含有する磁性体分散液４を得た。
【０２０８】
（磁性体分散液５の調製）
磁性体として、残留磁化の異なる磁性体
（残留磁化１５．３Ａｍ^２／ｋｇ、粒径０．２μ［０．０３〜０．１μｍ：１０個数％、０．３μｍ以上：３％］
シランカップリング剤［ｎ−Ｃ_４Ｈ_９Ｓｉ（ＯＣＨ_３）_３］０．２部処理、疎水化２６％）
を同量用いた以外は磁性体分散液１の調製と同様にして、中心径は０．２５μの着色剤粒子を含有する磁性体分散液５を得た。
【０２０９】
（離型剤分散液１の調製）
パラフィンワックス（融点ピーク温度 ９０℃） ５０重量部
カチオン性界面活性剤（花王社製、サニゾールＢ５０） ５．５重量部
イオン交換水 ２００重量部
前記成分を加圧下９８℃に加熱して、ＩＫＡ 社製ウルトラタラックスＴ５０で十分に分散した後、圧力吐出型ホモジナイザーで分散処理を施し、中心径０．１６μの離型剤粒子を含有する離型剤分散液を得た。
【０２１０】
（離型剤分散液２の調製）
ワックスとして
ポリエチレンワックス（融点ピーク温度１１２℃）
を同量用いた以外は離型剤分散液１の調製と同様にして、中心径は０．３８μの着色剤粒子を含有する磁性体分散液２を得た。
【０２１１】
（トナー１の製造）
樹脂微粒子分散液１ ２００重量部
磁性体分散液１ ２８３重量部
離型剤分散液１ ６４重量部
ポリ塩化アルミニウム １．２３重量部
前記成分を丸型ステンレス製フラスコ中でホモジナイザー（ＩＫＥ社製、ウルトラタラックスＴ５０）で十分に混合・分散した後、加熱用オイルバスでフラスコを攪拌しながら凝集温度５８℃まで加熱した。その後、５８℃で６０分間保持した後、さらに樹脂微粒子分散液１を３０重量部追加して緩やかに攪拌した。
【０２１２】
その後、０．５Ｍｏｌ／Ｌの水酸化ナトリウム水溶液で系内のｐＨを７．０に調整した後、ステンレス製フラスコを密閉し、磁力シールを用いて攪拌を継続しながら８０℃まで加熱した。その後、ｐＨを４．０まで低下して６時間保持した。反応終了後、冷却し、濾過、イオン交換水による十分な洗浄を行った後、ヌッチェ式吸引濾過により固液分離を施した。さらに、４０℃のイオン交換水３Ｌに再度分散し、１５分３００ｒｐｍで攪拌、洗浄した。
【０２１３】
この洗浄操作を５回繰り返した後、ヌッチェ式吸引濾過により固液分離を行った。次いで真空乾燥を１２時間継続し、その後疎水性シリカ（ヘキサメチルジシラザン処理、ＢＥＴ２００ｍ^２／ｇ）１．２部を外添してトナー１を得た。このトナー粒径をコールターカウンターで測定したところ、重量平均径６．６μ平均円形度０．９６８であった。またＸ線光電子分光分析により測定されるトナー表面に存在する炭素元素の含有量（Ａ）に対する鉄元素の含有量（Ｂ）の比（Ｂ／Ａ）が０．０００８であり、透過型電子顕微鏡（ＴＥＭ）を用いたトナーの断面観察によるＤ／Ｃ≦０．０２を満足する粒子数は８０％以上であった。
【０２１４】
トナー１の物性について表１に示す。
【０２１５】
（トナー２の製造）
トナー１の製造において、離型剤分散液２を同量添加したほかはトナー１の製造例１と同様の操作を行い、トナー２を得た。
【０２１６】
トナー２の物性について表１に示す。
【０２１７】
（トナー３の製造）
トナー１の製造において、磁性体分散液１を２９０部、離型剤分散液１を２５５部添加したほかはトナー１の製造例１と同様の操作を行い、トナー３を得た。
【０２１８】
トナー３の物性について表１に示す。
【０２１９】
（トナー４の製造）
トナー１の製造において、磁性体分散液２を同量添加したほかはトナー１の製造例１と同様の操作を行い、トナー４を得た。
【０２２０】
トナー４の物性について表１に示す。
【０２２１】
（トナー５の製造）
トナー１の製造において、磁性体分散液３を同量添加したほかはトナー１の製造例１と同様の操作を行い、トナー５を得た。
【０２２２】
トナー５の物性について表１に示す。
【０２２３】
（トナー６の製造）
トナー１の製造において、離型剤分散液１の添加量を固形分換算で１５．０重量％、着色剤分散液１の添加量を固形分換算で４．５重量％に変更し、凝集温度を６３℃、凝集停止後の８０℃到達時の系内ｐＨを５．０とした以外はトナー１の製造と同様に操作してトナー６を得た。
【０２２４】
（トナー７の製造）
トナー１の製造において、凝集温度を５３℃とし、凝集保持時間を４時間としたほかはトナー１の製造例１と同様の操作を行い、トナー７を得た。
【０２２５】
トナー７の物性について表１に示す。
【０２２６】
（トナー８の製造）
トナー１の製造において、磁性体分散液４を同量添加したほかはトナー１の製造例１と同様の操作を行い、トナー８を得た。
【０２２７】
トナー８の物性について表１に示す。
【０２２８】
（トナー９の製造）
トナー１の製造において、磁性体分散液１を７８０部添加したほかはトナー１の製造例１と同様の操作を行い、トナー９を得た。
【０２２９】
トナー９の物性について表１に示す。
【０２３０】
トナー１の製造において、樹脂分散液１ ３０部を追添加しないほかはトナー１の製造例１と同様の操作を行い、トナー１０を得た。
【０２３１】
トナー１０の物性について表１に示す。
【０２３２】
（トナー１１の製造）
トナー１の製造において、樹脂分散液１ ６０部を追添加するほかはトナー１の製造例１と同様の操作を行い、トナー１１を得た。
【０２３３】
トナー１１の物性について表１に示す。
【０２３４】
（トナー１２の製造）
トナー１の製造において、磁性体分散液５を同量添加するほかはトナー１の製造例１と同様の操作を行い、トナー１２を得た。
トナー１２の物性について表１に示す。
【外３】

【０２３５】
（実施例１）
トナー１を用いて、最もチャージアップしやすい低温低湿環境下（１５℃，１０％ＲＨ）で５０００枚の画出し試験を行った。その結果、連続５０００枚プリント後においても飛び散りの無い良好な画像が得られた。また、スリーブ上のトナーをエアで除去した後、目視観察をしたが、スリーブ上は現像剤固着も全くなかった。後述の評価方法による画像濃度、カブリ量及びドット再現性の評価結果を表２に示す。
【０２３６】
同様にして、高温高湿環境下（３２．５℃，８５％ＲＨ）において画出し試験をおこなった。結果を表３に示す。
【０２３７】
＜実施例２−９比較例１−３＞
表２に示す各トナー２−１２を用いて実施例１と同様に、低温低湿環境下（１５℃，１０％ＲＨ）で５０００枚の画出しを行った。
【０２３８】
後述の評価方法による画像濃度、カブリ量及びドット再現性の評価結果を表２に示す。
【０２３９】
同様にして、高温高湿環境下（３２．５℃，８５％ＲＨ）において画出し試験をおこなった。結果を表３に示す。
【外４】

【０２４０】
なお、画像評価は以下のように行った。
【０２４１】
感光体の削れ及びトナー融着の評価は、画像不良が現れやすいハーフトーン画像上に、削れあるいはトナー融着による画像不良、即ち黒点あるいは白抜けが発生した耐久枚数で判断した。発生するまでの耐久枚数が多い程、画像形成方法の耐久性が良好なことを意味する。これらの画像不良が発生しない場合は印字枚数５０００枚まで耐久試験を続けた。
【０２４２】
ａ）画像濃度の測定はマクベス濃度計ＲＤ９１８（マクベス社製）で測定した。
【０２４３】
ｂ）カブリの測定は、東京電色社製のＲＥＦＬＥＣＴＭＥＴＥＲ ＭＯＤＥＬＴＣ−６ＤＳを使用して測定した。フィルターは、グリーンフィルターを用い、下記の式より算出した。
【０２４４】
カブリ（反射率）（％）＝標準紙上の反射率（％）−サンプル非画像部の反射率（％）
カブリは、２．０％以下であれば良好な画像である。
【０２４５】
ｃ）ドット再現性は、図７に示す８０μｍ×５０μｍのチェッカー模様を用いて画出し試験をおこない、顕微鏡により黒色部の欠損の有無を観察し、評価した。
Ａ：１００個中欠損が２個以下
Ｂ：１００個中欠損が３〜５個
Ｃ：１００個中欠損が６〜１０個
Ｄ：１００個中欠損が１１個以上
ｄ）耐久初期（１００枚時）の転写効率は、ベタ黒画像転写後の感光体上の転写残トナーをマイラーテープにより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の値をＣ、転写後定着前のトナーの載った紙上にマイラーテープを貼ったもののマクベス濃度をＥ、未使用の紙上に貼ったマイラーテープのマクベス濃度をＤとした時、近似的に以下の式で計算した。
【外５】

【０２４６】
転写効率は９０％以上であれば問題のない画像である。
【図面の簡単な説明】
【図１】非接触現像方式を用いた画像形成装置の一例を示す図である。
【図２】図１に示した画像形成装置の現像器部分の拡大図である。
【図３】接触転写部材の一例を示す図である。
【図４】画像形成装置の現像バイアスのパターンを示す図である。
【図５】トナーの現像特性を試験するためのチェッカー模様の説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet recording method, and the like, and an image forming method. More specifically, the present invention relates to a toner and an image forming method used for a copying machine, a printer, and a facsimile, which form a toner image on an electrostatic latent image carrier in advance and then transfer the image onto a transfer material to form an image.
[0002]
[Prior art]
Conventionally, many methods are known as electrophotography, but generally, a photoconductive substance is used, and an electric latent image is formed on an electrostatic image carrier (hereinafter referred to as a “photoconductor”) by various means. Is formed, and then the latent image is developed with a toner to form a visible image. If necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat, pressure, or the like. To obtain a copy.
[0003]
As a method for visualizing an electric latent image, a cascade developing method, a magnetic brush developing method, a pressure developing method, and the like are known.
[0004]
U.S. Pat. No. 3,909,258 proposes a method of developing using an electrically conductive magnetic toner. In this technique, a conductive magnetic toner is supported on a cylindrical conductive sleeve having magnetism therein, and the toner is brought into contact with an electrostatic image for development. At this time, in the developing section, a conductive path is formed by the toner particles between the surface of the recording medium and the surface of the sleeve, and electric charges are guided to the toner particles from the sleeve via the conductive path, and a gap between the electrostatic image and the image area is formed. The toner particles adhere to the image area due to the Coulomb force and are developed. The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method.On the other hand, since the toner is conductive, the developed image can be transferred from a recording medium to plain paper or the like. There is a problem that it is difficult to transfer electrostatically to the final supporting member.
[0005]
As a developing method using a high-resistance magnetic toner capable of electrostatically transferring, there is a developing method using dielectric polarization of toner particles. However, such a method has a problem that the developing speed is essentially low and the density of a developed image is not sufficiently obtained, and is practically difficult.
[0006]
As another developing method using a high-resistance insulating magnetic toner, toner particles are frictionally charged by friction between the toner particles, friction between the toner particles and a sleeve, and the like, and are contacted with the electrostatic image holding member. Methods for developing are known. However, in this method, the number of times of contact between the toner particles and the friction member is small, and the magnetic toner used has a large amount of magnetic material exposed on the surface of the toner particles. There was such a problem.
[0007]
For example, in JP-A-54-43027 and JP-A-55-18656, a magnetic developer is thinly coated on a developer carrying member, and the magnetic developer is triboelectrically charged. A method of developing an image by bringing it into close proximity to an electrostatic latent image without making contact with the electrostatic latent image, that is, a so-called jumping development method is disclosed. According to this method, it is possible to sufficiently frictionally charge the developer by applying the magnetic developer thinly on the developer carrier, and to develop the developer without contacting the electrostatic latent image while supporting the developer by magnetic force. Is performed, transfer of the developer to the non-image portion, that is, fogging is suppressed, and a high-definition image can be obtained.
[0008]
Unlike the two-component system, such a one-component developing system does not require carrier particles such as glass beads and iron powder, so that the developing device itself can be reduced in size and weight. Further, in the two-component developing method, since it is necessary to keep the toner concentration in the developer constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device is also large and heavy here. In the one-component developing system, such an apparatus is not required, so that it is preferable because it can be made small and light.
[0009]
However, the developing method using the insulating magnetic toner has an unstable factor relating to the insulating magnetic toner to be used. The reason is that a considerable amount of fine powdered magnetic material is mixed and dispersed in the insulating magnetic toner, and a part of the magnetic material is exposed on the surface of the toner particles. The characteristics of the magnetic toner are changed, and as a result, various characteristics required for the magnetic toner such as development characteristics and durability of the magnetic toner are changed or deteriorated.
[0010]
It is considered that the above problem occurs when a magnetic toner containing a conventional magnetic material is used, because the magnetic material is exposed on the surface of the magnetic toner. That is, by exposing the magnetic fine particles having relatively low resistance as compared with the resin constituting the toner on the surface of the magnetic toner, the toner charging performance is reduced, the toner fluidity is reduced, and the In use, the deterioration of the developer is caused, such as a decrease in image density due to the separation of the magnetic material due to the rubbing between the toners or the regulating member, and the occurrence of density unevenness called a sleeve ghost.
[0011]
On the other hand, the toner is prepared by melt-mixing a binder resin, a colorant, and the like, uniformly dispersing the mixture, pulverizing with a fine pulverizer, and classifying with a classifier to obtain a toner having a desired particle size (pulverization method). However, there is a limitation on the material selection range for reducing the toner particle size. For example, the resin colorant dispersion must be sufficiently brittle and capable of being pulverized with economically available manufacturing equipment. From this requirement, in order to make the resin colorant dispersion brittle, when the resin colorant dispersion is actually finely pulverized at a high speed, particles having a wide particle size range are easily formed, and in particular, a relatively large proportion of fine particles ( The problem is that excessively pulverized particles are included in this. Further, such a highly brittle material is often further pulverized or powdered when used as a developing toner in a copying machine or the like.
[0012]
Further, in the pulverization method, it is difficult to completely and uniformly disperse solid fine particles such as a magnetic powder or a colorant in a resin, and depending on the degree of the dispersion, it causes an increase in fog and a decrease in image density. . Further, in the pulverization method, magnetic iron oxide particles are essentially exposed on the surface of the toner, so that there remains a problem in the fluidity of the toner and the charging stability under a severe environment.
[0013]
That is, in the pulverization method, there is a limit to the fineness of the toner required for high definition and high image quality, and along with this, the powder characteristics, especially the uniform charging property and fluidity of the toner are significantly attenuated.
[0014]
In order to overcome the problems of the toner by the pulverization method as described above and further satisfy the above requirements, a suspension polymerization method, an association / salting-out method after emulsion polymerization (hereinafter referred to as an association polymerization method), an interface There has been proposed a method of producing a toner by a so-called polymerization method in which a monomer or the like is charged into a solvent to directly form a toner, such as a polymerization method and a dispersion polymerization method.
[0015]
Among them, the toner by association polymerization can easily be manufactured with a narrow toner particle size distribution as disclosed in Japanese Patent Publication Nos. 2557646, 2547011-2547016, and 2537503. In addition, since the toner particles have no edge portion and can be formed into a thermal sphere, they have excellent transfer characteristics and are advantageous for high image quality.
[0016]
However, when the magnetic material is contained in the associative polymerized toner, its fluidity and charging characteristics when left unattended are significantly reduced.
[0017]
This means that a large amount of surfactant is used in the production, so that charge leakage is likely to occur, and that the magnetic iron oxide particles are exposed on the toner surface as in the case of the pulverization method because aggregation and aggregation are essentially uniform. As a result, the fluidity is reduced and problems such as toner fusion and scraping occur.
[0018]
Further, in order to realize sufficient fixability at a low temperature, it is necessary to use a low Tg or low melting point resin as a thermoplastic resin. When used, a part of the toner adheres to the fixing roller at the time of fixing, and the so-called offset phenomenon occurs where the toner is transferred to the non-image area. The toner is rubbed around the regulating blade in the developing machine. This causes a problem of mutual aggregation or fusion.
[0019]
From such a point of view, improvements as in the prior art have been proposed.
[0020]
For example, regarding the exposure of a coloring agent such as a magnetic substance, in the case of the association polymerization method, various methods are used as a manufacturing method for producing a encapsulated toner by depositing polymer fine particles on the surface of the toner base particles and then forming a film of the polymer fine particles. A method has been proposed.
[0021]
For example, JP-A-57-45558 describes a method of adding a water-soluble inorganic salt or changing the pH when polymer fine particles formed by emulsion polymerization are adhered to the surface of a toner base particle. I have. This method has problems such as partial elution of the magnetic substance and slight incorporation of the inorganic salt into the toner, and is still insufficient from the viewpoint of chargeability.
[0022]
JP-A Nos. 1-257853 to 1-257856 disclose that when a fine particle formed by emulsion polymerization is adhered to the surface of a toner base particle obtained by suspension polymerization, a mixed solution of the base particle and the fine particle is used. A method is disclosed in which a water-soluble polymerization initiator is added to cause a reaction. According to this method, it is possible to uniformly cover the surface of the toner base particles with the fine particles, but only the fine particles are adhered in the form of particles, and in order to form a uniform film, the amount of the fine particles is greatly increased. It is necessary to coat thickly, and the fixability is rather deteriorated.
[0023]
Further, JP-A-2-186363, JP-A-4-188155 and JP-A-5-281782 disclose that fine particles formed by emulsion polymerization on the surface of toner base particles are dry-mixed, A manufacturing method has been disclosed in which fine particles are electrostatically attached and then fixed by an impact force. Although this method has an advantage that it can be coated by a dry method, it is difficult to re-disperse the dried fine particles into the primary particles, and it is difficult to uniformly attach the fine particles to the surface of the toner base particles.
[0024]
Japanese Patent Application Laid-Open No. Hei 7-209904 discloses a method of achieving both fixability and durability by providing a toner surface layer portion, which is a suspension polymerization toner but has no magnetic particles due to encapsulation, from the same viewpoint. However, when such a developer has a small average particle size of, for example, 10 μm, the volume in which the magnetic particles can exist is small, and thus it is difficult to include a sufficient amount of the magnetic particles. Moreover, in such a developer, the ratio of the surface resin layer where no magnetic particles are present differs between the developer particles having a large particle size and the developer particles having a small particle size in the particle size distribution of the developer. Thus, the content of the magnetic substance included therein is different, and the developability and transferability also differ depending on the particle size of the developer, that is, the selective developability depending on the particle size is easily observed. Therefore, even in a toner having a sharp particle size distribution such as an association polymerization method, particles which are hard to be developed because they contain a large amount of magnetic material, that is, developer particles having a large particle size are likely to remain, and the image density and image quality are lowered, and further, the fixing property is reduced. It also leads to deterioration.
[0025]
In addition, in any of the above-mentioned association polymerization methods, when a magnetic material is used as a colorant, the magnetic material hinders thermal spheroidization. There was a tendency for the coating amount to change due to the unevenness, and there was a case where the transferability and the chargeability during durability were insufficient. Further, in order to reduce the influence of the irregularities of the toner, it is necessary to perform an excessive heat treatment in order to form a true sphere shape, for example, a temperature much higher than that of the resin Tg. It has been found that exposure occurs and transferability and developability deteriorate.
[0026]
From this point of view, it is necessary to improve the magnetic material, but at present, sufficient knowledge regarding the improvement of the magnetic material has not been obtained from the viewpoint of the association polymerization method.
[0027]
Regarding the magnetic substance, for example, in a suspension polymerization method toner, although from the viewpoint of improving the dispersibility of the magnetic substance, many proposals have been made regarding surface modification.
[0028]
For example, JP-A-59-200254, JP-A-59-200256, JP-A-59-200257 and JP-A-59-224102 disclose various techniques for treating a magnetic substance with a silane coupling agent. Japanese Patent Application Laid-Open No. 63-250660 discloses a technique for treating magnetic particles containing silicon elements with a silane coupling agent, and Japanese Patent Application Laid-Open No. 7-72654 discloses a method in which magnetic iron oxide is alkylated. A technique of treating with trialkoxysilane is disclosed.
[0029]
However, when the above techniques are used for the association polymerization method, these treatments improve the fluidity of the magnetic material and improve the dispersibility in the toner to some extent, but decrease the chargeability and the toner melting due to thermal spheroidization. It has been found that there has been little improvement with respect to issues such as a decrease in the transferability and transferability, and that there is still room for study.
[0030]
In addition, in the case of the associative polymerization method, since it is necessary to aggregate with emulsified particles in water, the magnetic material having a high degree of hydrophobicity is easily aggregated, and a large amount of a surfactant having the opposite polarity to the emulsified particles and a small amount of the magnetic material are added. It is necessary to devise a process such as addition, which leads to a decrease in chargeability and an increase in cost.
[0031]
As for printer devices, LED and LBP printers have become the mainstream in the recent market, and the direction of technology has been increased to higher resolution, that is, 240,300 dpi has been changed to 400,600,800 dpi. Accordingly, the development method is also required to have higher definition. In addition, the functions of the copiers have also been enhanced, and therefore the digital copier is moving toward digitalization. In this direction, the method of forming an electrostatic latent image with a laser is the main method, so it is also proceeding in the direction of high resolution, and here, similarly to printers, a high resolution and high definition development method is required. I have. For this reason, the particle size of the toner has been reduced, and JP-A-1-112253, JP-A-1-191156, JP-A-2-214156, JP-A-2-284158, and JP-A-3-181952. And Japanese Patent Application Laid-Open No. 4-162048 propose a toner having a specific particle size distribution and a small particle size.
[0032]
In recent years, from the viewpoint of environmental protection, the primary charging and transfer process using a photoreceptor abutting member has become mainstream from the primary charging and transfer process using corona discharge.
[0033]
In the primary charging and transfer process using corona discharge, a large amount of ozone is generated when corona discharge, especially negative corona is generated, so it is necessary to provide a filter for capturing ozone in the electrophotographic apparatus. There are problems such as an increase in size or an increase in running cost. Further, image problems caused by such a corona charging method include, for example, so-called image deletion caused by a decrease in the surface resistance of the photoreceptor due to attachment of nitrogen oxide or the like, or a problem that the electrophotographic apparatus is stopped. A memory phenomenon of the photoreceptor caused by ions remaining in the charger is exemplified.
[0034]
As a technique for solving such a problem, a charging member such as a roller or a blade or a transfer member is brought into contact with the surface of the photoreceptor to form a narrow space near the contact portion and can be interpreted by the so-called Paschen's law. A contact charging method or a contact transfer method in which such a discharge is formed to minimize the generation of ozone has been developed. For example, JP-A-57-178257, JP-A-56-104351, and JP-A-58-104351 This technology is known in Japanese Patent Application Laid-Open Nos. 40566, 58-139156 and 58-150975. Among these, in particular, a charging method and a transfer method using a conductive elastic roller as described in JP-A-63-149669 and JP-A-2-123385 are preferably used from the viewpoint of stability. ing.
[0035]
However, it has been found that when the contact charging method or the contact transfer method is used, there is an alarming problem unlike the case where corona discharge is used.
[0036]
Specifically, first, in the case of the contact transfer method, the transfer member is brought into contact with the photoreceptor via the transfer member at the time of transfer, so that the toner image formed on the photoreceptor is transferred to the transfer material. Are pressed against each other, which causes a problem of partial transfer failure called so-called “missing transfer”. Further, as the direction of recent technology, a developing method with higher resolution and higher definition has been demanded, and in order to respond to such a demand, the particle diameter of the toner has been reduced. As described above, as the toner particle size becomes smaller, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photoreceptor becomes larger than the Coulomb force applied to the toner particles in the transfer process, and as a result, the transfer residual As a result, the amount of toner increases, and the transfer failure tends to further worsen.
[0037]
On the other hand, in the contact charging method, the charging member is pressed against the surface of the photoreceptor with a pressing pressure. Therefore, when the untransferred residual toner, that is, the transfer residual toner, is pressed against the surface of the photoreceptor, abrasion due to the abrasion of the surface of the photoreceptor or toner fusion in which the scraped portion is a nucleus is likely to occur. It becomes more noticeable as the amount of residual toner increases.
[0038]
Such scraping of the photoreceptor and fusion of the toner cause a serious defect in forming an electrostatic latent image on the electrostatic image carrier. Specifically, since the primary charge cannot be performed when the photosensitive member is scraped, the scraped portion appears black on the halftone image. In addition, since toner fusion makes it impossible to form a latent image by exposure, a fused portion appears white on a halftone image. Further, the transferability of the toner is also deteriorated. Therefore, in combination with the above-mentioned transfer failure, a remarkable image defect appears, and in some cases, the deterioration of the image quality is accelerated synergistically.
[0039]
Such a problem of abrasion of the photoreceptor and poor transfer is likely to occur when a developer composed of irregular toner particles is used. This is presumably because the transferability of the irregular toner is low and the edge of the toner particles easily scratches the surface of the photoreceptor.
[0040]
Furthermore, the problem of shaving becomes particularly remarkable when a magnetic developer having a magnetic material exposed on the surface of toner particles is used. This is easily understood considering that the exposed magnetic body is directly pressed against the photoconductor.
[0041]
Furthermore, if the transfer residual toner increases, it becomes difficult to maintain sufficient contact between the contact charging member and the photoreceptor, and the charging property is deteriorated. Is more likely to occur. This phenomenon is often seen under low humidity where the resistance of the member tends to increase.
[0042]
As described above, in an image forming method using a contact charging method and a contact transfer method, which are very preferable in consideration of the environment, development of a magnetic developer having high transferability and less likely to cause abrasion of the photoreceptor and toner fusing is required. Is desired.
[0043]
When using a magnetic toner containing a conventional magnetic material, the above-mentioned problem is caused largely by the fact that the magnetic material is exposed on the surface of the toner of any of the conventional magnetic toners. is there. In the case of a magnetic toner in which a magnetic material is exposed on the toner surface, the resistance of the magnetic material is lower than the resistance of the resin of the toner, so that the charging characteristics under high humidity tend to be poor, and the fog suppression is deteriorated, and the transfer is deteriorated. This leads to undesirable effects such as ghosting due to a reduction in transferability, a reduction in the recovery of transfer residual toner, and a deterioration in the performance of the photoreceptor due to rubbing with the photoreceptor.
[0044]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner and an image forming method which solve the above-mentioned problems of the related art.
[0045]
An object of the present invention is to provide a toner that is less affected by the environment, has stable charging performance, has a high image density even when used for a long time, suppresses fogging, and has excellent image reproducibility. is there.
[0046]
An object of the present invention is to provide an image forming method that combines a contact charging process that generates less ozone and a non-contact developing process that uses less fog using a one-component developer. It is another object of the present invention to provide an image forming method in which an image defect is less likely to occur even when used for a long period of time by using a magnetic developer which has little transfer residual toner and hardly scrapes the photoreceptor surface.
[0047]
[Means for Solving the Problems]
The present invention has toner particles obtained by aggregation-associating at least resin particles and iron oxide, and i) with respect to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy (A). The ratio (B / A) of the content (B) of the iron element is less than 0.001, and ii) the projected area equivalent diameter of the toner is C, and the cross section of the toner is observed using a transmission electron microscope (TEM). Assuming that the minimum value of the distance between the iron oxide and the toner surface is D, 30% by number or more of the toner satisfies the relationship of D / C ≦ 0.02, and iii) the magnetic field of the magnetic toner is 79.6 kA / m. (1000 Oersted) the residual magnetization intensity is 1 to 6.2 Am²/ Kg (emu / g).
[0048]
The present invention further provides a charging step of charging the electrostatic image carrier by a charging member to which an external voltage is applied; an exposure step of forming an electrostatic latent image on the electrostatic image carrier by exposure; A developing step of developing a latent image with toner carried on a toner carrier to form a toner image; and a transferring step of transferring the toner image to a transfer material, wherein the toner comprises at least a toner image. And i) the iron element content (B) relative to the carbon element content (A) present on the toner surface as measured by X-ray photoelectron spectroscopy. ) Is less than 0.001, and ii) the projected area equivalent diameter of the toner is C, and the iron oxide and toner surface in the cross-sectional observation of the toner using a transmission electron microscope (TEM) are observed. D is the minimum distance In this case, the number of toners satisfying the relationship of D / C ≦ 0.02 is at least 50% by number, and iii) the magnetic toner has a remanence of 1 to 6 at a magnetic field of 79.6 kA / m (1000 Oersted). .1 Am²/ Kg (emu / g).
[0049]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have conducted intensive studies on the improvement of charge uniformity and stabilization of the magnetic toner by the association polymerization method. As a result, the presence state near the surface of the magnetic material and the thermal deformation during the thermal sphering / resin coating process were observed. The inventors have found that ease has greatly affected various characteristics such as chargeability and transferability, and have reached the present invention.
[0050]
Specifically, the ratio (B / A) of the iron element content (B) to the carbon element content (A) present on the toner surface measured by X-ray photoelectron spectroscopy is less than 0.001, When the projected area equivalent diameter of the toner is C, and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D, D / C ≦ 0.02. When the toner that satisfies the relationship is 30% by number or more, the magnetic material is appropriately present near the surface to improve the chargeability, and the magnetic field of the toner is 79.6 kA / m (1000 Oe). ) Is 0.6 to 6.2 Am²/ Kg (emu / g) is selected so that magnetic aggregation in the emulsified aggregation state of the magnetic substance is easily broken, and thermal spheroidization under mild conditions / resin Because coating is possible, the exudation of wax and the like is suppressed. ・ Even if the amount of surfactant that inhibits charging is reduced, stable production can be achieved. The present invention has been achieved by adopting a configuration to be made.
[0051]
Also, by using the toner as described above, even in an image forming method including a contact charging step, a one-component non-contact developing step, and a contact transfer step in which a large stress is applied to the toner, the photoreceptor is significantly shaved, poorly charged, and poorly transferred. The inventors have found that high-definition images can be stably obtained without being fogged or other image defects even after long-term use, and the present invention has been achieved.
[0052]
One of the features of the present invention is to use a magnetic material having a specific remanent magnetization and to have a remanence intensity of 0.6 to 6.2 Am in a magnetic field of 79.6 kA / m (1000 Oe) as a toner.²/ Kg (emu / g).
[0053]
As a result of intensive studies, the present inventors have found that the difficulty of thermal spheroidization in the associative polymerization method is caused by magnetic aggregation of a magnetic material, and as a toner, a magnetic field of 79.6 kA / m (1000 Oersted). Is 6.2 Am²/ Kg (emu / g), more preferably 5.0 Am²It has been found that heat treatment can be easily performed by selecting a magnetic substance so as to be less than / kg (emu / g).
[0054]
For this reason, the intensity of the remanent magnetization is 6.2 Am²/ Kg (emu / g), preferably 5.0 Am²/ Kg (emu / g), it is necessary to greatly increase the amount of fine particles and coat thickly in order to form a uniform film of the magnetic material as in the conventional case, and the fixing property is rather deteriorated. Further, in the case of an associative polymerization toner containing a wax and having a low-temperature fixing property, the toner is liable to be broken / scratched due to durability, and the transferability is deteriorated, and the toner is fused to the photoreceptor due to stress during contact charging and contact transfer. Tends to occur.
[0055]
It is unknown at which point in the manufacturing process of associative polymerization the magnetic substance forms a magnetic aggregation structure, but it is magnetized during the production of the magnetic substance or when the magnetic substance is put into the association / polymerization system from the hopper. I think it will be lost.
[0056]
From the viewpoint of recoverability of the toner on the sleeve in the one-component development, the toner of the present invention has a residual magnetization of 0.6 Am in a magnetic field of 79.6 kA / m (1000 Oe).²/ Kg (emu / g) or more, more preferably 1.0 Am²/ Kg (emu / g).
[0057]
The method for controlling the residual magnetization in the present invention can be used by any known means as long as it is a magnetic substance falling within the scope of the present invention. For example, Japanese Patent Application Laid-Open Nos. 10-101339 and 2000-319629 disclose oxidation methods. A method for manufacturing a magnetic material in which a metal such as phosphorus, silica, and titanium is added to iron is used.
[0058]
Since it is more advantageous for the toner of the present invention to have an appropriate magnetic cohesion structure with respect to the coloring power of the toner of the present invention, in the present invention, the magnetic material having low residual magnetization is appropriately hydrophobized, It is preferable to improve the dispersibility of the polymer.
[0059]
Specifically, it is preferable to use a magnetic substance having a hydrophobicity of 5 to 90% as the degree of hydrophobicity of the magnetic substance. If the degree of hydrophobicity is less than 5%, the image density decreases. In addition, the image density is lowered, and in addition, fogging and the like are easily caused by the influence of the magnetic material treating agent.
[0060]
The content of the magnetic substance in the toner binder resin of the present invention is determined by the coloring power and the residual magnetization / saturation magnetization of the magnetic substance of the present invention. Is preferable, and addition of 20 to 180 parts is more preferable.
[0061]
If the addition amount is less than 10 parts, more preferably less than 20 parts, the coloring power is reduced, and it is difficult to suppress fog. If the addition amount exceeds 180 parts, more preferably more than 200 parts, the coloring power is sufficient, but the developer is carried. The coercive force due to the magnetic force on the body is increased and the developability is reduced, and a large amount of resin coating is required to suppress the exposure of the magnetic body, and as a result, the fixability and the developability deteriorate.
[0062]
As the coupling agent that can be used in the magnetic material of the present invention, all known treatment agents can be used, and examples include a silane coupling agent and a titanium coupling agent. More preferably used is a silane coupling agent, having the general formula
RmSiYn
[Wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group such as an alkyl group, a vinyl group, a glycidoxy group, a methacryl group, and n represents an integer of 1 to 3. Show. ]. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethyl Examples include methoxysilane, hydroxypropyltrimethoxysilane, enyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.
[0063]
In particular, the expression
C_pH_{2p + 1}-Si- (OC_qH_{2q + 1})₃
[Wherein, p represents an integer of 2 to 20, and q represents an integer of 1 to 3] The iron oxide is hydrophobized in an aqueous medium using an alkyl trialkoxysilane coupling agent represented by the formula: Is good.
[0064]
If p in the above formula is smaller than 2, the hydrophobizing treatment is easy, but it is difficult to impart sufficient hydrophobicity. If p is larger than 20, the hydrophobicity is sufficient, but iron oxide is not sufficient. The coalescence of the particles increases, and it becomes difficult to sufficiently disperse the iron oxide particles in the toner.
[0065]
On the other hand, when q is larger than 3, the reactivity of the silane coupling agent is reduced, and it is difficult to sufficiently perform the hydrophobic treatment.
[0066]
In particular, alkyltrialkoxysilane in which p represents an integer of 2 to 20 (more preferably an integer of 3 to 15) and q represents an integer of 1 to 3 (more preferably an integer of 1 or 2). It is good to use a coupling agent.
[0067]
The treatment amount is 0.05 to 20 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of iron oxide.
[0068]
In the present invention, the aqueous medium is a medium containing water as a main component. Specific examples of the aqueous medium include water itself, water in which a small amount of a surfactant is added, water in which a pH adjuster is added, and water in which an organic solvent is added. As the surfactant, a nonionic surfactant such as polyvinyl alcohol is preferable. The surfactant is preferably added in an amount of 0.1 to 5% by mass based on water. Examples of the pH adjuster include an inorganic acid such as hydrochloric acid.
[0069]
The stirring is performed sufficiently by a mixer having a stirring blade (specifically, a high shear mixing device such as an attritor or a TK homomixer) so that the iron oxide fine particles become primary particles in an aqueous medium. Is good.
[0070]
Since the surface of the iron oxide particles thus obtained is uniformly subjected to a hydrophobic treatment, when used as a toner material, the dispersibility in the toner becomes very good.
[0071]
The iron oxide used in the toner of the present invention is produced, for example, by the following method.
[0072]
An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or more than the iron component to the aqueous ferrous sulfate solution. While maintaining the pH of the prepared aqueous solution at pH 7 or more (preferably pH 8 to 10), air is blown into the aqueous solution, and while the aqueous solution is heated to 70 ° C. or more, the oxidation reaction of ferrous hydroxide is carried out. First, a seed crystal is produced.
[0073]
Next, an aqueous solution containing about 1 equivalent of ferrous sulfate based on the amount of the alkali added previously is added to the slurry-like liquid containing the seed crystals. The reaction of ferrous hydroxide is promoted while blowing air while maintaining the pH of the solution at 6 to 10 to grow magnetic iron oxide particles around the seed crystal. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but it is preferable that the pH of the liquid is not less than 6. At the end of the oxidation reaction, adjust the pH of the solution, stir well so that the magnetic iron oxide becomes primary particles, and in the case of aqueous hydrophobic treatment, add a coupling agent and mix and stir well. Dry, lightly crushed to obtain hydrophobically treated magnetic iron oxide particles. Alternatively, after the oxidation reaction is completed, the iron oxide particles obtained by washing and filtering are redispersed in another aqueous medium without drying, and then the pH of the redispersed liquid is adjusted, and the mixture is sufficiently stirred. A coupling treatment may be performed by adding a silane coupling agent.
[0074]
As the ferrous salt, iron sulfate generally produced as a by-product in the production of titanium sulfate, iron sulfate produced as a by-product of cleaning the surface of a steel sheet, and iron chloride can be used.
[0075]
The method for producing magnetic iron oxide by the aqueous solution method generally uses an iron concentration of 0.5 to 2 mol / liter from the viewpoint of preventing an increase in viscosity during the reaction and the solubility of iron sulfate. Generally, the lower the concentration of iron sulfate, the smaller the particle size of the product tends to be. In addition, in the reaction, as the amount of air is larger and the reaction temperature is lower, the particles are easily atomized.
[0076]
By using the hydrophobic iron oxide particles thus produced for the toner, it is possible to obtain the toner of the present invention having excellent image characteristics and stability.
[0077]
The iron oxide used as a magnetic material in the toner of the present invention may contain an element such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, or silicon, and mainly includes triiron tetroxide and γ-iron oxide. These components are used alone or in combination of two or more. These iron oxides preferably have a BET specific surface area of 2 to 30 m by a nitrogen adsorption method.²/ G, especially 3 to 28 m²/ G and a Mohs' hardness of 5 to 7 are more preferable.
[0078]
Examples of the shape of the iron oxide include an octahedron, a hexahedron, a sphere, a needle, a scale, and the like, and an octahedron, a hexahedron, a sphere, and an amorphous material having little anisotropy increase the image density. Preferred above. Such a shape can be confirmed by SEM or the like. As the particle size of the iron oxide, in the measurement of the particle size of particles having a particle size of 0.03 μm or more, the volume average particle size is 0.1 to 0.3 μm, and 0.03 to 0.1 μm Is preferably 40% by number or less.
[0079]
When an image is obtained from a magnetic toner using iron oxide having an average particle size of less than 0.1 μm, the color of the image shifts to reddish, and the blackness of the image becomes insufficient. It is not generally preferable, for example, the tendency to feel strong is increased. Further, since the surface area of the iron oxide increases, the dispersibility decreases, and the energy required during production increases, which is not efficient. Further, the effect of iron oxide as a coloring agent is weakened, and the density of an image may be insufficient, which is not preferable.
[0080]
On the other hand, if the average particle diameter of iron oxide exceeds 0.3 μm, the mass per particle increases, so that the probability of exposure to the toner surface due to the difference in specific gravity with the binder during production increases, This is not preferred because the likelihood of such an increase becomes significant and the sedimentation stability of the dispersion decreases.
[0081]
If the number of particles of iron oxide of 0.1 μm or less exceeds 40% by number in the toner, the surface area of the iron oxide increases, the dispersibility is reduced, and aggregates are easily generated in the toner. The content is preferably 40% by number or less because the possibility of impairing the chargeability and decreasing the coloring power increases. Further, when the content is 30% by number or less, the tendency is further reduced, which is more preferable.
[0082]
Incidentally, iron oxide having a particle diameter of less than 0.03 μm receives a small stress at the time of toner production due to a small particle diameter, and thus has a low probability of appearing on the surface of the toner particles. Furthermore, even if it is exposed on the particle surface, it hardly acts as a leak site, so that there is substantially no problem. Therefore, in the present invention, attention is paid to particles of 0.03 to 0.1 μm, and the number% thereof is defined.
[0083]
Further, when the number of particles of 0.3 μm or more in the iron oxide exceeds 10% by number, the coloring power is reduced, and the image density tends to be reduced. It is not preferable because it is difficult to stably exist near the surface of the toner particles and to make each toner particle contain a uniform number. More preferably, it is set to 5% by number or less.
[0084]
In the present invention, it is preferable to use iron oxide production conditions that have been set or the particle size distribution has been adjusted in advance such as pulverization and classification so as to satisfy the above-mentioned particle size distribution conditions. As a classification method, for example, a method using sedimentation separation such as centrifugation or a thickener, or a means such as a wet classification device using a cyclone is preferable.
[0085]
The determination of the volume average particle size and the particle size distribution of the iron oxide is performed by the following measurement method. With the particles sufficiently dispersed, the projected area of each of the 100 iron oxide particles in the visual field was measured with a transmission electron microscope (TEM) at a magnification of 30,000 times, and the measured area of each particle was measured. The equivalent diameter of a circle equal to the projected area was determined as each particle diameter. Further, based on the results, the volume average particle size was calculated, and the number% of particles having a particle size of 0.03 to 0.1 μm and particles having a particle size of 0.3 μm or more was calculated. The particle size was measured for particles having a particle size of 0.03 μm or more. Further, the particle size can be measured by an image analyzer.
[0086]
When determining the volume average particle size and the particle size distribution of the iron oxide in the toner particles, the following measurement method is used.
[0087]
After sufficiently dispersing the toner particles to be observed in the epoxy resin, the cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days is obtained as a flaky sample by a microtome, and is observed by a transmission electron microscope (TEM). In the photograph at a magnification of 10,000 to 40,000 times, the projected area of each of the particle diameters of 100 iron oxides in the field of view was measured, and the equivalent diameter of a circle equal to the measured projected area of each particle was measured. It was determined as the particle size. Further, based on the result, the number% of the particles of 0.03 to 0.1 μm and the number of particles of 0.3 μm or more were calculated. Further, the particle size can be measured by an image analyzer.
[0088]
Another feature of the present invention is that a magnetic material is present in the vicinity of the surface appropriately. That is, the ratio of the content (B) of the iron element (B) to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy as a definition of the state of the magnetic substance near the toner surface (B / A) Is less than 0.001, the projected area equivalent diameter of the toner is C, and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D, One of the aspects required for the toner of the present invention is that the toner satisfying the relationship of D / C ≦ 0.02 is 30% by number or more.
[0089]
First, in the present invention, the ratio (B / A) of the iron element content (B) to the carbon element content (A) present on the toner surface measured by X-ray photoelectron spectroscopy (B / A) is preferably less than 0.001. It is preferable that the magnetic material is not exposed at all on the surface so that the value is less than 0.0005.
[0090]
By not exposing the magnetic material, it is possible to suppress various adverse effects such as the deterioration of the photoreceptor at the time of durability such as scraping and fogging / transfer as described above. However, regarding the charging property itself, if no magnetic material is present near the surface, the adverse effects such as charge-up and selective development tend to occur as described above, so the magnetic material must be present appropriately near the surface. .
[0091]
That is, in the present invention, the number of toners satisfying the relationship of D / C ≦ 0.02 needs to be 30% or more, preferably 65% or more, and more preferably 75% or more.
[0092]
When the number of toners satisfying the relationship of D / C ≦ 0.02 is less than 30%, magnetic particles do not exist at all outside at least the boundary of D / C = 0.02 in almost all toners. become. If such particles are assumed to be spherical, at least 11.5% of the space where no iron oxide exists on the surface of the toner when one toner is used as the whole space. In fact, it is clear that the iron oxide is 12% or more because the iron oxide is not uniformly arranged at the closest position so as to form an inner wall inside the toner. In the toner composed of such particles, various adverse effects are likely to occur as described above.
[0093]
In the present invention, as a specific method of measuring D / C by TEM, the D / C can be obtained by sufficiently dispersing particles to be observed in a room temperature curable epoxy resin and then curing the particles in an atmosphere at a temperature of 40 ° C. for 2 days. It is preferable to observe the cured product as it is or as a flaky sample using a microtome provided with diamond teeth after freezing.
[0094]
The specific method for determining the ratio of the number of particles in question is as follows. For the particles for determining D / C by TEM, the equivalent circle diameter was determined from the cross-sectional area in a micrograph, and the value was ± 10% of the number average particle diameter determined by the method described below using a Coulter counter. And the minimum value (D) of the distance from the magnetic particle surface to 100 corresponding particles is measured, D / C is determined, and the particle having a D / C value of 0.02 or less is determined. Calculate the percentage. The micrograph at this time is preferably at a magnification of 10,000 to 20,000 times in order to perform highly accurate measurement. In the present invention, observation was performed at an accelerating voltage of 100 kV using a transmission electron microscope (H-600 manufactured by Hitachi) as an apparatus, and observation and measurement were performed using a micrograph with a magnification of 10,000 times.
[0095]
As described in detail above, a toner in which the number of toners satisfying the relationship of B / A <0.001 and satisfying the relationship of D / C ≦ 0.02 is 30% or more is such that the magnetic material is localized on the toner surface. It is not a toner that is present or, conversely, is extremely encapsulated and unevenly distributed inside the toner. A toner in which the exposure of the magnetic material is suppressed.
[0096]
In order to achieve the magnetic substance dispersion state of the present invention in the associative polymerization method, polymer fine particles were adhered to the surface of the toner base particles as long as elution of the magnetic substance and excessive change in surface properties were not obtained. Thereafter, all of the known production methods and seed / swelling polymerization methods for forming an encapsulated toner by forming a film of the polymer fine particles can be used. For example, JP-A-57-45558 and JP-A-1-25753 described above. All the techniques disclosed in JP-A-1-257856, JP-A-2-186363, JP-A-4-188155, JP-A-5-281782, JP-A-7-209904 and the like can be used. .
[0097]
However, when the toner is not the toner having the specific residual magnetization described above in the present invention, since thermal coating or seed polymerization is performed while maintaining the unevenness, the toner tends to be unevenly coated, so that the chargeability and transferability are reduced, and the toner is further deteriorated. Cracks, scratches, etc., are likely to occur, so that the magnetic material is exposed, wax exudes, and the like. As a result, the state of the toner surface of the present invention cannot be maintained, and the development and transfer properties are particularly deteriorated. Further, if a large amount of heat coating or seed polymerization is performed to cover the surface, not only the fixability is deteriorated, but also toner fusion is likely to occur due to the influence of wax ooze.
[0098]
Next, the circularity of the toner, which is a further feature of the present invention, will be described. In order to reduce toner adhesion to the non-image portion on the electrostatic image carrier and the amount of transfer residual toner, it is necessary that the chargeability of the toner particles is sufficient and uniform. Furthermore, when a toner having a small particle diameter is used from the viewpoint of improving image quality, the adhesive force of the toner particles increases, so that the shape of the toner particles has a great effect on the toner adhesion to the non-image portion on the electrostatic image carrier. Effect. In other words, the closer the toner particles are spherical and the shape is uniform, the smaller the adhesion area of the particles, the smaller the amount of toner attached to the non-image area on the electrostatic image carrier and the amount of residual toner for transfer, and the higher image quality and durability Stability is achieved.
[0099]
In addition, the toner particles according to the present invention have sufficient chargeability and, as described above, the adhesion of the toner particles is reduced, so that the toner particles can be transferred from the electrostatic image carrier to a transfer material such as paper. Transfer efficiency is also greatly improved. This can be said to be an important toner performance for achieving high resolution as well as reproducibility of a minute dot image.
[0100]
In addition, since the associative polymerization toner of the present invention has no edge portion in the particles, the magnetic cohesion between the toner particles also tends to be improved as it becomes spherical, and as a result, image tailing is reduced.
[0101]
Therefore, in the toner of the present invention, the average circularity of the toner needs to be 0.950 or more, thereby achieving high image quality and high stability.
[0102]
Therefore, when such a developer is used, transfer residual toner is greatly reduced, so that the amount of toner present in the pressure contact portion between the charging member and the photoconductor is very small, and even in an image forming method having a contact charging step. It is considered that the photoreceptor is prevented from being scraped and the toner is fused, and image defects are remarkably suppressed.
[0103]
These effects become remarkable even in an image forming method including a contact transfer step in which a dropout during transfer is likely to occur.
[0104]
In the toner of the present invention, the weight average particle diameter is preferably 2 to 10 μm.
[0105]
When the weight average particle diameter of the toner exceeds 10 μm, the reproducibility of the fine dot image is reduced, and thus the toner cannot exhibit sufficient charge stability under the severe environment obtained by the present invention. On the other hand, when the weight average particle diameter of the toner is smaller than 2 μm, even if the special iron oxide of the present invention is used, the fluidity of the toner becomes extremely low, and problems such as fogging and light density due to poor charging are likely to occur. Become.
[0106]
That is, in the toner of the present invention, remarkable effects such as improvement in charge stability and fluidity appear on the image as compared with the conventional example because the weight average particle diameter is 2 to 10 μm (more preferably, 3 to 10 μm). ), And from the viewpoint of further improving the image quality, the thickness is preferably 3.5 to 8.0 μm.
[0107]
Next, a method for producing a toner according to the present invention will be described.
[0108]
The toner of the present invention uses resin particles produced by emulsion polymerization or the like. Using a resin particle dispersion liquid in which resin particles are dispersed in an ionic surfactant, and mixing this with a colorant dispersed with an opposite polarity ionic surfactant to cause hetero-aggregation and aggregation corresponding to the toner diameter After the particles are formed, the aggregated particles are fused and coalesced by heating to a temperature equal to or higher than the glass transition temperature of the resin particles, and washed and dried to obtain a toner. According to this method, a toner having a desired shape from an irregular shape to a spherical shape can be manufactured.
[0109]
Also, the toner components can be mixed and aggregated, aggregated, fused and coalesced to be manufactured, but in the initial stage of the aggregation step, the balance of the amount of the polar ionic dispersant is shifted in advance, For example, using a polymer of an inorganic metal salt such as calcium nitrate or a polymer of an inorganic metal salt such as polyaluminum chloride, the ionic potential deviation is reduced, and the first-stage matrix aggregate particles are formed at a temperature lower than the glass transition temperature and stable. After that, as a second step, an additional particle dispersion liquid treated with a polarity and an amount of a dispersant to compensate for the above-mentioned imbalance is added, and further included in the base aggregated particles and the additional particles as necessary. After heating the resin slightly below the glass transition temperature of the resin to attach additional particles to the surface of the matrix aggregated particles and stabilizing it at a higher temperature, heat it above the glass transition temperature to fuse and coalesce. It may be. Further, the stepwise operation of the aggregation may be repeatedly performed a plurality of times.
[0110]
As the polymer used for the resin particles of the present invention, a combination of known monomers can be used. Specifically, styrenes such as styrene, parachlorostyrene, α-methylstyrene, etc .; methyl acrylate, acrylic acid Vinyl such as ethyl, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate Esters having a group; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; ethylene and propylene Polyolefins such as butadiene; divinylbenzene, ethylene diacrylate, ethylene dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, deethylene ethylene diacrylate, decaethylene dimethacrylate Glycol, pentaethylene glycol diacrylate, pentaethylene glycol dimethacrylate, pentacontactor diacrylate, pentacontactor dimethacrylate, decanediol diacrylate, decanediol dimethacrylate, etc., alone or in combination of two or more. May be used.
[0111]
When a vinyl monomer is used as the binder resin component of the present invention, a resin particle dispersion can be prepared by performing emulsion polymerization using an ionic surfactant or the like, and using other resins. If the solvent is oily and soluble in a solvent with relatively low solubility in water, dissolve the resin into those solvents and mix it with water using a homogenizer or other dispersing machine together with an ionic surfactant or polymer electrolyte. The resin dispersion can be prepared by dispersing the solvent into fine particles and then evaporating the solvent by heating or reducing the pressure. The particle size of the obtained resin fine particle dispersion is measured by, for example, a laser diffraction type particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). The center particle diameter of the resin fine particles used in the present invention is suitably in the range of 50 to 400 nm, preferably 70 to 350 nm. If it is less than 50 nm, the cohesiveness is slightly inferior and the productivity tends to decrease.
[0112]
The glass transition temperature (Tg) of the toner in the present invention is in the range of 50 to 65C, preferably 52 to 60C. If the temperature is lower than 50 ° C., the cohesive force of the binder resin itself in a high temperature range is reduced, so that hot offset tends to occur at the time of fixing. If the temperature exceeds 65 ° C., sufficient melting is not obtained, and the fixing sheet is bent. Resistance may worsen.
[0113]
In addition, the toner of the present invention preferably contains a release agent in an amount of 0.5 to 50% by mass based on the binder resin. Normally, a toner image is transferred onto a transfer material in a transfer step, and then this toner image is fixed on the transfer material by energy such as heat and pressure to obtain a semi-permanent image. As a fixing method at this time, a hot roll fixing method is generally used, and as described above, a very high-definition image can be obtained by using a toner having a weight average particle diameter of 10 μm or less. When a transfer material such as paper is used, the toner particles having a small diameter enter gaps between fibers of the paper, insufficiently receive heat from the heat fixing roller, and low-temperature offset is likely to occur. However, by including an appropriate amount of wax as a release agent in the toner of the present invention, it is possible to prevent shaving of the photoreceptor while achieving both high resolution and offset resistance.
[0114]
The wax usable in the toner of the present invention is represented by paraffin wax, microcrystalline wax, petroleum wax such as petrolactam and its derivatives, montan wax and its derivatives, hydrocarbon wax and its derivatives by Fischer-Tropsch method, and polyethylene. And natural waxes and derivatives thereof, such as polyolefin waxes and their derivatives, carnauba wax and candelilla wax. The derivatives herein include oxides, block copolymers with vinyl monomers, and graft-modified products. Further, fatty acids such as higher aliphatic alcohols, stearic acid and palmitic acid or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes can also be used.
[0115]
These release agents (waxes) are dispersed in water together with an ionic surfactant and a polymer electrolyte such as a polymer acid or a polymer base, and then heated to a melting point or higher using a homogenizer or a pressure discharge type disperser. Fine particles are formed by applying strong shearing while heating, and a dispersion liquid of fine particles of 1 μm or less can be prepared. The particle size of the obtained release agent particle dispersion is measured by, for example, a laser diffraction type particle size distribution analyzer (LA-700 manufactured by Horiba, Ltd.). The center particle diameter of the release agent particles used in the present invention is suitably in the range of 50 to 400 nm, preferably 70 to 350 nm. If the thickness is less than 50 nm, the exudation property of the release agent at the time of fixing is likely to be reduced, which may cause poor peeling. On the other hand, if it exceeds 400 nm, release agent particles having a size of 1500 nm or more are likely to be formed at the time of aggregation, and the OHP transparency may be impaired.
[0116]
Among these wax components, those having a maximum endothermic peak in a region of 40 to 110 ° C. when the temperature is raised, and a maximum endothermic peak in a region of 45 to 90 ° C. in a DSC curve measured by a differential scanning calorimeter are preferable. Those having a peak are more preferred. By having the maximum endothermic peak in the above-mentioned temperature range, the releasability can be effectively exhibited while greatly contributing to low-temperature fixing. If the maximum endothermic peak is less than 40 ° C., the self-cohesive force of the wax component becomes weak, and as a result, the high-temperature offset resistance deteriorates. On the other hand, if the maximum endothermic peak exceeds 110 ° C., the fixing temperature becomes high, and low-temperature offset tends to occur, which is not preferable. Further, when the toner is directly obtained by a polymerization method by performing granulation / polymerization in an aqueous medium, if the maximum endothermic peak temperature is high, the wax component is likely to be liberated mainly in the process of association and aggregation, resulting in a decrease in transfer efficiency and durability. It is not preferable because a problem such as a decrease in image density occurs.
[0117]
The measurement of the maximum endothermic peak temperature of the wax component is performed according to “ASTM D3418-8”. For the measurement, for example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of the calorific value uses the heat of fusion of indium. An aluminum pan was used as a measurement sample, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.
[0118]
In the toner of the present invention, the content of the wax component is preferably in the range of 0.5 to 50% by mass based on the binder resin. If the content of the wax component is less than 0.5% by mass, the effect of suppressing the low-temperature offset is poor, and if it exceeds 50% by mass, the long-term storability is reduced, and the dispersibility of other toner materials is deteriorated. This leads to deterioration in fluidity and deterioration of image characteristics.
[0119]
In the present invention, inorganic fine particles can be added in a wet manner in order to stabilize the charging property. Examples of the inorganic fine particles to be added include silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate, which are usually added externally to the toner surface, and are used with an ionic surfactant, a polymer acid, It can be used by being dispersed in a molecular base.
[0120]
Further, for the purpose of imparting fluidity to the toner and improving the cleaning property, after drying the toner in the same manner as a normal toner, inorganic particles such as silica, alumina, titania, calcium carbonate, fine particles of a vinyl resin, polyester, silicone Resin fine particles such as the above can be used by adding to the toner surface by shearing in a dry state.
[0121]
A charge control agent may be added to the toner of the present invention in order to stabilize the charge characteristics. As the charge control agent, a known charge control agent can be used. However, a charge control agent which is particularly fast in charging speed and can stably maintain a constant charge amount is preferable.
[0122]
Specific compounds include salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, metal compounds of aromatic carboxylic acids such as dicarboxylic acids, metal salts or metal complexes of azo dyes or azo pigments, and sulfones as negative charge control agents. Examples thereof include a high molecular compound having an acid or carboxylic acid group in a side chain, a boron compound, a urea compound, a silicon compound, and calixarene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in a side chain, a guanidine compound, a nigrosine compound, and an imidazole compound. It is preferable to use 0.5 to 10 parts by mass of these charge control agents based on 100 parts by mass of the polymerizable monomer. However, in the developer related to the image forming method of the present invention, the addition of a charge control agent is not essential, and the toner in the toner is positively used by positively utilizing the triboelectric charge between the layer pressure regulating member of the developer and the developer carrier. Need not necessarily include a charge control agent.
[0123]
In the present invention, another coloring agent may be used in addition to iron oxide as a coloring agent. Coloring materials that can be used in combination include magnetic or non-magnetic inorganic compounds, known dyes and pigments. Specifically, for example, ferromagnetic metal particles such as cobalt and nickel or chromium, manganese, copper, zinc, aluminum and alloys added with rare earth elements, hematite, titanium black, nigrosine dye / pigment, carbon black, Phthalocyanine. These may also be used after treating the surface.
[0124]
In the method for producing a toner of the present invention, examples of surfactants used for emulsion polymerization, colorant dispersion, resin fine particle dispersion, release agent dispersion, aggregation, or stabilization thereof include, for example, sulfate ester salts and sulfonate salts. , Phosphate-based, soap-based anionic surfactants, amine salt-type and quaternary ammonium salt-type cationic surfactants, polyethylene glycol-based, alkylphenol-ethylene oxide adduct-based, polyhydric alcohol-based, etc. It is also effective to use a nonionic surfactant in combination. As a dispersing means, a rotary shearing homogenizer, a ball mill having a media, a sand mill, a dyno mill, or the like can be used.
[0125]
When using a composite comprising a resin and a magnetic material, a method of dissolving and dispersing the resin and the magnetic material in a solvent, dispersing the resin and the magnetic material in water together with an appropriate dispersant, and removing the solvent by heating and reducing pressure. Alternatively, it can be prepared and prepared by a method of applying a mechanical shear force to the surface of resin fine particles prepared by emulsion polymerization, or a method of electrically adsorbing and fixing. These methods are effective for suppressing the release of the magnetic substance as additional particles.
[0126]
After completion of the polymerization, a desired toner is obtained through an optional washing step, solid-liquid separation step, and drying step. In the washing step, it is preferable to perform sufficient replacement washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration and the like are preferred from the viewpoint of productivity. The drying step is not particularly limited, but freeze drying, flash jet drying, fluidized drying, vibration type fluidized drying and the like are preferably used from the viewpoint of productivity.
[0127]
Further, it is preferable that an inorganic fine powder or a hydrophobic inorganic fine powder is mixed with the toner of the present invention as a fluidity improver. For example, titanium oxide fine powder, silica fine powder, and alumina fine powder are preferably added and used, and particularly preferably, silica fine powder is used.
[0128]
The inorganic fine powder used in the developer has a specific surface area of 30 m due to nitrogen adsorption measured by the BET method.²/ G or more, especially 50 to 400 m²/ G is preferable because good results can be obtained.
[0129]
As the silica fine powder used in the present invention, both a so-called dry method produced by the vapor phase oxidation of a silicon halide and a so-called wet silica produced from water glass or the like and dry silica called fumed silica can be used. However, dry silica having few silanol groups on the surface and inside and having no production residue is preferably used.
[0130]
Further, the silica fine powder used in the present invention is preferably subjected to a hydrophobic treatment. The hydrophobizing treatment is applied by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the silica fine powder. As a preferable method, a method of treating a dry silica fine powder produced by a vapor phase oxidation of a silicon halide compound with a silane coupling agent, or simultaneously treating with a silane coupling agent with an organosilicon compound such as silicone oil. Is mentioned.
[0131]
Examples of the silane coupling agent used in the hydrophobizing treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, and allylphenyldichlorosilane. , Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilanemercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, Dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyl Examples include tetramethyldisiloxane and 1,3-diphenyltetramethyldisiloxane.
[0132]
Examples of the organosilicon compound include silicone oil. Preferred silicone oils have a viscosity of about 30 to 1,000 mm at 25 ° C.²/ S (cSt), for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil are preferred.
[0133]
As a method of treating the silicone oil, for example, the silica fine powder treated with the silane coupling agent and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the silicone oil may be injected into the base silica. It is good depending on the method. Alternatively, the silicone oil may be dissolved or dispersed in an appropriate solvent, mixed with a base silica fine powder, and the solvent may be removed.
[0134]
If necessary, an external additive other than the fluidity improver may be added to the toner of the present invention.
[0135]
For example, the primary particle size exceeds 30 nm (preferably the specific surface area is 50 m²/ G), more preferably the primary particle size is 50 nm or more (preferably the specific surface area is 30 m²/ G) is also one of the preferred forms. For example, it is preferable to use spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles.
[0136]
Still other additives, for example lubricant powders such as Teflon® powder, zinc stearate powder, polyvinylidene fluoride powder; or abrasives such as cerium oxide powder, silicon carbide powder, strontium titanate powder; anti-caking agents; or For example, a conductivity-imparting agent such as carbon black powder, zinc oxide powder, and tin oxide powder; and organic fine particles and inorganic fine particles of opposite polarity can be added in small amounts as a developing property improver. These additives can also be used after their surfaces have been subjected to a hydrophobic treatment.
[0137]
As described above, the external additive is preferably used in an amount of 0.1 to 5 parts by mass (preferably 0.1 to 3 parts by mass) based on 100 parts by mass of the toner.
[0138]
As a method of applying a mechanical impact force to the associative polymerization toner of the present invention to coat the resin, for example, a method using a mechanical impact pulverizer such as a Kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industries, Ltd. is there.
[0139]
In addition, like devices such as Hosokawa Micron's Mechano Fusion System and Nara Machinery Co., Ltd.'s hybridization system, high-speed rotating blades push the toner inside the casing by centrifugal force, and compressive force, frictional force, etc. A method of applying a mechanical impact force to the toner may be used.
[0140]
In the case of performing a process of applying a mechanical impact, the ambient temperature during the process is set to a temperature near the glass transition point Tg of the toner (that is, a temperature in the range of ± 30 ° C. of the glass transition point Tg) to prevent aggregation. And from the viewpoint of productivity. More preferably, processing at a temperature in the range of ± 20 ° C. of the glass transition point Tg of the toner is particularly effective for improving transfer efficiency.
[0141]
Furthermore, the toner of the present invention can be prepared by a method of atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in Japanese Patent Publication No. 56-13945 to obtain a spherical toner, Represented by a dispersion polymerization method in which the polymer obtained in step 1 is used to directly produce a toner using an insoluble aqueous organic solvent, or a soap-free polymerization method in which a polymer is produced by directly polymerizing in the presence of a water-soluble polar polymerization initiator. It can also be produced by a method of producing a toner using an emulsion polymerization method or the like.
[0142]
Next, a developing method using the toner of the present invention will be described.
[0143]
In the present invention, the toner carrier and the electrostatic image carrier are not in contact with each other.
[0144]
In the non-contact developing method, a magnetic toner is applied on the toner carrier with a layer thickness smaller than the closest distance (between S and D) between the toner carrier and the photoconductor (electrostatic image carrier). The development is performed by applying an electric field. That is, a layer thickness regulating member that regulates the magnetic toner on the toner carrier is set so that the closest gap between the photoconductor and the toner carrier is wider than the toner layer thickness on the toner carrier. At this time, it is particularly preferable that the layer thickness regulating member that regulates the magnetic toner on the toner carrier is an elastic member and is in contact with the toner carrier through the toner from the viewpoint of uniformly charging the magnetic toner. .
[0145]
Further, it is preferable that the toner carrier is provided to face the photoconductor with a separation distance of 100 to 500 μm, and it is further preferable that the toner carrier is installed to face the photoconductor with a separation distance of 120 to 500 μm. preferable. If the separation distance of the toner carrier from the photoconductor is smaller than 100 μm, the change in the developing characteristic of the toner with respect to the fluctuation of the separation distance becomes large, and it becomes difficult to mass-produce an image forming apparatus satisfying stable image quality. . If the separation distance of the toner carrier from the photoconductor is larger than 500 μm, the recoverability of the transfer residual toner to the developing device is reduced, and fog due to poor recovery is likely to occur. Further, since the followability of the toner to the latent image on the photoconductor is reduced, image quality such as resolution is reduced and image density is reduced.
[0146]
In the present invention, 5 to 30 g / m.²It is preferable that the toner layers are laminated so as to form a toner layer. The amount of toner on the toner carrier is 5 g / m²If it is smaller than this, it is difficult to obtain a sufficient image density, and the toner layer becomes uneven due to excessive charging of the toner. The amount of toner on the toner carrier is 30 g / m²If the number is larger than the above range, toner scattering tends to occur.
[0147]
The surface roughness Ra (JIS center line average roughness) of the toner carrier used in the present invention is preferably in the range of 0.2 to 3.5 μm. When Ra is less than 0.2 μm, the charge amount on the toner carrier increases, and the developability becomes insufficient. On the other hand, when Ra exceeds 3.5 μm, unevenness occurs in the lamination of the toner on the toner carrier, resulting in uneven density on the image. The surface roughness Ra is more preferably in the range of 0.5 to 3.0 μm.
[0148]
In the present invention, the surface roughness Ra of the toner carrier is measured using a surface roughness measuring device (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness "JIS B0601". Center line average roughness. Specifically, a 2.5 mm portion as the measurement length a is extracted from the roughness curve in the direction of the center line, the center line of the extracted portion is the X axis, the longitudinal magnification direction is the Y axis, and the roughness curve is When y = f (x), the value obtained by the following equation is expressed in micrometers (μm).
[Outside 1]

[0149]
Furthermore, since the magnetic toner according to the present invention has a high charging ability, it is preferable to control the total charge amount of the toner during development. The surface of the toner carrier according to the present invention is preferably coated with a resin layer in which conductive fine particles and / or a lubricant are dispersed.
[0150]
As the conductive fine particles contained in the resin layer covering the surface of the toner carrier, a conductive metal oxide such as carbon black, graphite and conductive zinc oxide and a metal double oxide are used alone or in combination of two or more. Is preferred. Examples of the resin in which the conductive fine particles and / or the lubricant are dispersed include a phenol resin, an epoxy resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyolefin resin, a silicone resin, a fluorine resin, and a styrene resin. Known resins such as resins and acrylic resins are used. Particularly, a thermosetting resin or a photocurable resin is preferable.
[0151]
In the non-contact developing method, it is preferable that the moving speed of the toner carrier that carries the toner in the developing step and transports the toner to the developing unit is different from the moving speed of the photoconductor. By providing such a speed difference, toner particles can be sufficiently supplied from the toner carrier side to the photoconductor side, and a good image can be obtained.
[0152]
The surface of the toner carrier that carries the toner may move in the same direction as the moving direction of the surface of the photoconductor, or may move in the opposite direction. As for the speed at this time, it is preferable that one of them moves at a speed of 1.02 to 3.0 times the other than the moving speed of the surface of the toner carrier and the surface of the photoconductor is constant.
[0153]
In the developing section, an AC bias is applied to transfer the magnetic toner to an electrostatic latent image for development. At this time, the AC bias has an electric field strength of at least 3 × 10⁶~ 1 × 10⁷V / m, and preferably at a frequency of 100 to 5000 Hz. It is also a preferable embodiment to further superimpose a DC bias.
[0154]
Next, the charging step will be described.
[0155]
In the present invention, a non-contact charging step such as a charging step using a charging device using corona discharge may be used, but a contact charging method in which a charging member is brought into contact with a photoreceptor is a preferable charging method. In this case, it is preferable to use a charging roller as the contact charging member.
[0156]
As a preferable process condition when the charging roller is used, a contact pressure of the roller is 4.9 to 490 N / m (5 to 500 g / cm), and a DC voltage or a DC voltage with an AC voltage superimposed thereon is used. . When an AC voltage is superimposed on a DC voltage, the AC voltage is preferably 0.5 to 5 kVpp, the AC frequency is 50 to 5 kHz, and the DC voltage is preferably ± 0.2 to ± 5 kV.
[0157]
Other charging means include a method using a charging blade and a method using a conductive brush. Also when these contact charging means are used, there is an effect that a high voltage becomes unnecessary and generation of ozone is reduced.
[0158]
The material of the charging roller and the charging blade as the contact charging means is preferably a conductive rubber, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVdF (polyvinylidene fluoride), PVdC (polyvinylidene chloride), or a fluoroacrylic resin can be used.
[0159]
Next, the transfer step will be described.
[0160]
In the present invention, a non-contact transfer step such as a transfer step using a transfer device using corona discharge may be used, but preferably a contact step in which transfer is performed by bringing a transfer unit into contact with a photoreceptor via a transfer material. This is a transfer method.
[0161]
The contact pressure of the transfer unit is preferably 2.9 N / m (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more. If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because the transfer of the transfer material and the occurrence of transfer failure tend to occur.
[0162]
Further, as a transfer unit in the contact transfer step, an apparatus having a transfer roller or a transfer belt is used. FIG. 5 shows an example of the configuration of the transfer roller. The transfer roller 34 includes at least a metal core 34a and a conductive elastic layer 34b, and the conductive elastic layer is made of an elastic material having a volume resistance of about 106 to 1010 Ωcm, such as urethane or EPDM in which a conductive material such as carbon is dispersed. Thus, a transfer bias is applied by a transfer bias power supply 35.
[0163]
Next, the photoreceptor used in the present invention will be described below.
[0164]
As the photosensitive member, a photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as a-Se, CdS, ZnO2, OPC (organic photosensitive member), and a-Si is preferably used.
[0165]
In particular, in the present invention, it is preferable to use a photoreceptor whose surface is mainly composed of a polymer binder. For example, when a protective film (protective layer) mainly composed of resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or a charge transport layer of a function-separated type organic photoreceptor is composed of a charge transport material and a resin. There is a case where a surface layer is provided, and a case where a protective layer mainly composed of resin is provided on the surface layer. These surface layers (or protective layers) preferably have releasability, and as a means for actually providing releasability,
(1) A resin having a low surface energy is used for the resin constituting the film.
(2) Add an additive that imparts water repellency and lipophilicity,
{Circle around (3)} powdery material having high releasability is dispersed;
Means and the like. Examples of (1) include introducing a functional group such as a fluorine-containing group or a silicone-containing group into the structure of the structural unit of the resin. Examples of the additive that imparts water repellency and lipophilicity of (2) include a surfactant. Examples of the material having high releasability of (3) include compounds containing a fluorine atom, that is, polytetrafluoroethylene, polyvinylidene fluoride, and carbon fluoride.
[0166]
By these means, the contact angle of the photoreceptor surface with water can be 85 degrees or more, and the transferability of the toner and the durability of the photoreceptor can be further improved. The contact angle of the photoreceptor surface with water is preferably 90 degrees or more. In the present invention, among the means (1) to (3), it is preferable to disperse the fluororesin releasable powder in the outermost surface layer as in (3). It is particularly preferable to use polytetrafluoroethylene as the powder.
[0167]
In order to contain these powders on the surface, a layer in which a releasable powder is dispersed in a binder resin is provided on the outermost surface of the photoreceptor, or the photoreceptor itself is mainly composed of a resin. In the case of an organic photoreceptor, a release powder may be dispersed in the uppermost layer without providing a new surface layer. The addition amount of the releasable powder is preferably from 1 to 60% by mass, more preferably from 2 to 50% by mass, based on the total amount of the surface layer. If the amount of the releasable powder is less than 1% by mass, the effect of improving the transferability of the toner and the durability of the photoreceptor is insufficient. This is not preferable because the amount of light incident on the body is significantly reduced.
[0168]
In the present invention, a contact charging method in which the charging means abuts the charging member on the photoreceptor is a preferable charging method, but the charging means does not contact the photoreceptor with respect to the surface of the photoreceptor as compared with a method by corona discharge or the like. Since the load is large, providing a protective layer (protective film) on the surface of the photoreceptor has a remarkable effect of improving the durability, and is one of the preferable embodiments.
[0169]
Further, in the present invention, since it is preferable to apply a contact charging method and a contact transfer method, it is particularly effectively used for an image forming apparatus having a photoreceptor having a small diameter of 50 mm or less. That is, when the diameter of the photoreceptor used in image formation is small, the curvature for the same linear pressure is large, and the concentration of pressure in the contact portion is likely to occur. Although it is considered that the same phenomenon occurs in the belt photoreceptor, the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer section.
[0170]
One preferred embodiment of the photoreceptor used in the present invention will be described below.
[0171]
Examples of the conductive substrate include a metal such as aluminum and stainless steel, an aluminum alloy, a plastic having a coating layer of an indium oxide-tin oxide alloy, a paper impregnated with conductive particles, a plastic, and a plastic cylindrical material having a conductive polymer. Cylinders and films are used.
[0172]
On these conductive substrates, the photosensitive layer has improved adhesion, improved coating properties, protection of the substrate, coating of defects on the substrate, improved charge injection from the substrate, and protection against electrical breakdown of the photosensitive layer. An undercoat layer may be provided for the purpose. The undercoat layer is made of polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymer nylon, glue, gelatin, polyurethane , Made of a material such as aluminum oxide. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably about 0.1 to 3 μm.
[0173]
The charge generation layer includes azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium pigments, pyrylium salts, thiopyrylium salts, triphenylmethane pigments, selenium, and amorphous silicon. It is formed by dispersing a charge generating substance such as an inorganic substance in a suitable binder and coating or by vapor deposition. Examples of the binder include a polycarbonate resin, a polyester resin, a polyvinyl butyral resin, a polystyrene resin, an acrylic resin, a methacrylic resin, a phenol resin, a silicone resin, an epoxy resin, and a vinyl acetate resin. A binder can be arbitrarily selected. The amount of the binder contained in the charge generation layer is preferably 80% by mass or less, more preferably 0 to 60% by mass, based on the entire charge generation layer. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.05 to 2 μm.
[0174]
The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting material in a solvent together with a binder resin if necessary, and applying the solution. The thickness of the charge generation layer is generally 5 to 40 μm. As the charge transport substance, biphenylene, anthracene, pyrene, a polycyclic aromatic compound having a structure such as phenanthrene, indole, carbazole, oxadiazole, a nitrogen-containing cyclic compound such as pyrazoline, a hydrazone compound, Examples include styryl compounds, selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide.
[0175]
Examples of the binder resin for dispersing these charge transporting substances include resins such as polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin, acrylic resin, and polyamide resin, and organic resins such as poly-N-vinylcarbazole and polyvinylanthracene. Photoconductive polymers are mentioned.
[0176]
Further, a protective layer may be further provided as a surface layer. As the resin of the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent of these resins can be used alone or in combination of two or more.
[0177]
Further, conductive fine particles may be dispersed in the resin of the 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, and antimony. Ultrafine particles of coated tin oxide and zirconium oxide may be mentioned. These conductive fine particles may be used alone or in combination of two or more. Generally, when particles are dispersed in the protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The conductive fine particles preferably have a particle size of 0.3 μm or less. Further, the content of the conductive fine particles in the protective layer is preferably from 2 to 90% by mass, more preferably from 5 to 80% by mass, based on the total weight of the protective layer. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.
[0178]
The application of the surface layer can be performed by spray coating, beam coating or permeation (dipping) coating of the resin dispersion.
[0179]
Next, the image forming method of the present invention will be specifically described with reference to the drawings.
[0180]
In the image forming apparatus of FIG. 1, reference numeral 100 denotes a photosensitive drum, around which a primary charging roller 117, a developing device 140, a transfer charging roller 114, a cleaner 116, a register roller 124, and the like are provided. Then, the photoconductor 100 is charged to, for example, −700 V by the primary charging roller 117. (Applied voltage is AC voltage -2.0 kVpp, DC voltage -700 Vdc) Then, the photoconductor 100 is exposed by irradiating the laser beam 123 to the photoconductor 100 by the laser generator 121. The electrostatic latent image on the photoconductor 100 is developed with a one-component magnetic developer by a developing device 140, and is transferred onto a transfer material by a transfer roller 114 that is in contact with the photoconductor via the transfer material. The transfer material bearing the toner image is carried to a fixing device 126 by a conveyor belt 125 or the like, and is fixed on the transfer material. Further, the toner left partially on the photoconductor is cleaned by the cleaning unit 116. As shown in FIG. 2, the developing device 140 is provided with a cylindrical toner carrier 102 (hereinafter referred to as a developing sleeve) made of a non-magnetic metal such as aluminum or stainless steel in the vicinity of the photoconductor 100. The gap between the sleeve 100 and the developing sleeve 102 is maintained at about 300 μm by a sleeve / photoconductor gap holding member (not shown) or the like. Inside the developing sleeve, a magnet roller 104 is fixed and arranged concentrically with the developing sleeve 102. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown, S1 affects development, N1 regulates the amount of toner coating, S2 influences the intake / conveyance of toner, and N2 affects prevention of toner blowing. The toner is applied to the developing sleeve 102 by the toner applying roller 141, adhered and transported. An elastic blade 103 is provided as a member for regulating the amount of toner to be conveyed. In the developing area, a DC and AC developing bias is applied between the photoconductor 100 and the developing sleeve 102, and the developer on the developing sleeve flies on the photoconductor 100 according to the electrostatic latent image to become a visible image. .
[0181]
The method for measuring various physical property data in the present invention will be described in detail below.
[0182]
(1) Ratio of iron element content (B) to carbon element content (A) present on toner surface (B / A)
The ratio (B / A) of the content (B) of the iron element to the content (A) of the carbon element present on the toner surface in the present invention was calculated by performing surface composition analysis by ESCA (X-ray photoelectron spectroscopy). .
[0183]
In the present invention, the ESCA apparatus and measurement conditions are as follows.
Apparatus used: 1600S type X-ray photoelectron spectrometer manufactured by PHI (Physical Electronics Industries, Inc.)
Measurement conditions: X-ray source MgKα (400W)
Spectral area 800μmφ
In the present invention, the surface atomic concentration (atomic%) was calculated from the measured peak intensity of each element using a relative sensitivity factor provided by PHI.
[0184]
As a measurement sample, a toner is used, but when an external additive is added to the toner, the toner is washed with a solvent that does not dissolve the toner, such as isopropanol, and the measurement is performed after removing the external additive. Do.
[0185]
(2) Average circularity of toner
The circularity in the present invention is used as a simple method for quantitatively expressing the shape of a particle. In the present invention, the particle shape is measured using a flow-type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. And the circularity is determined by the following equation. Further, as shown by the following formula, a value obtained by dividing the total of the measured circularities of all the particles by the total number of particles is defined as an average circularity.
[Outside 2]

[0186]
In addition, "FPIA-1000" which is a measuring device used in the present invention calculates the circularity of each particle, and then calculates the average circularity. 1.000 divided by 0.010 at intervals of 0.400 or more and less than 0.410, 0.410 or more and less than 0.420: 0.990 or more and less than 1.000, and 61 divided ranges such as 1.000 And a calculation method of calculating the average circularity using the center value and the frequency of the division points is used.
[0187]
The error between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-described calculation formula that directly uses the circularity of each particle is extremely small, and is substantially small. Since it is negligible, the present invention uses the above-described concept of the calculation formula that directly uses the circularity of each particle for data handling reasons such as shortening the calculation time and simplifying the calculation formula. However, such a calculation method partially modified is used.
[0188]
The circularity in the present invention is an index indicating the degree of unevenness of the particles, and is 1.000 when the particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated.
[0189]
As a specific method of measuring the circularity, about 5 mg of a toner is dispersed in 10 ml of water in which about 0.1 mg of a nonionic surfactant is dissolved to prepare a dispersion, and an ultrasonic wave (20 kHz, 50 W) is applied. And the dispersion liquid concentration is set to 5,000 to 20,000 / μl, and the circularity distribution of particles having a circle equivalent diameter of 3 μm or more is measured using the above-mentioned flow type particle image measuring device.
[0190]
The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 version) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring device, and JP-A-8-136439. It is.
[0191]
The sample dispersion liquid is passed through a flow path (spread along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be positioned on opposite sides of the flow cell so as to form an optical path that intersects with the thickness of the flow cell. While the sample dispersion is flowing, strobe light is applied at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a range parallel to the flow cell. Photographed as a two-dimensional image. The diameter of a circle having the same area is calculated as the equivalent circle diameter from the area of the two-dimensional image of each particle. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above-described circularity calculation formula.
[0192]
(3) Particle size distribution of toner
A Coulter Counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were connected. A 1% NaCl aqueous solution is prepared using graded sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of the toner were measured using the Coulter Counter TA-II using a 100 μm aperture as the aperture. Calculate the volume distribution and number distribution of 〜40 μm particles. Then, the weight-average diameter D4 (the median value of each channel is a representative value for each channel) obtained from the number-average particle diameter (D1) volume distribution, and the weight of 12.7 μm or more obtained from the volume distribution. Find the distribution.
[0193]
(4) Degree of hydrophobicity of magnetic material
The degree of hydrophobicity in the present invention is measured by the following method. The degree of hydrophobicity of the magnetic substance is measured by a methanol titration test. The methanol titration test is an experimental test for confirming the degree of hydrophobicity of a magnetic substance having a hydrophobized surface.
[0194]
The measurement of the degree of hydrophobicity using methanol is performed as follows. 0.1 g of the magnetic material is added to 50 ml of water in a 250 ml beaker. Thereafter, methanol is gradually added to the liquid and titration is performed. At this time, methanol is supplied from the bottom of the liquid and the stirring is carried out gently. The termination of the sedimentation of the magnetic substance is defined as the time when the suspended matter of the magnetic substance is no longer confirmed on the liquid surface, and the degree of hydrophobicity is expressed as a volume percentage of methanol in the mixed solution of methanol and water when the sedimentation termination point is reached. .
[0195]
(Example)
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. The toner of the present invention is prepared by preparing the following resin fine particle dispersion, colorant dispersion, and release agent dispersion, mixing them at a predetermined ratio, stirring, and adding an inorganic metal salt polymer thereto. And ionically neutralized to form aggregated particles. After adjusting the pH of the system from weakly acidic to neutral with an inorganic hydroxide, the resin fine particles are heated to a temperature equal to or higher than the glass transition temperature of the resin fine particles, and the temperature is raised to the fusion / coalescing temperature. After the fusion / coalescing temperature is reached, the pH in the system is adjusted from weakly acidic to acidic and heating is continued. After completion of the reaction, a desired toner is obtained through a sufficient washing, solid-liquid separation and drying steps. Hereinafter, each preparation method will be described. In addition, the number of parts or% described in the examples indicates parts by mass or% by mass.
[0196]
Next, image forming apparatuses used in Examples 1 to 6 and Comparative Examples 1 to 4 will be described.
[0197]
A commercially available laser beam printer LBP-SX (manufactured by Canon Inc.) which performs development by a non-contact development method was used as modified below. That is, an LBP printer was used in which the toner layer thickness regulating member in the process cartridge portion was changed to an elastic blade made of urethane rubber.
[0198]
The image forming conditions are shown below.
[0199]
FIG. 6 illustrates the alternating voltage used. Vdc represents a DC power supply voltage, Vd represents a dark portion potential on the electrostatic latent image carrier, and VL represents a bright portion potential. f indicates the frequency of the alternating voltage, and Vpp indicates the voltage between the peaks of the alternating voltage.
[0200]
An electrostatic latent image is formed by setting Vd to −600 V, a gap (300 μm) is set without contact between the photosensitive drum 3 and the developer layer on the developing sleeve 15, and an AC bias is applied to the developing sleeve 15 by bias applying means 12. (F = 3200 Hz Vpp = 1800 V) and a DC bias (Vdc = −400 V) were applied, and VL was set to −150 V to perform image display.
[0201]
Further, the peripheral speed ratio of the developing sleeve to the photosensitive drum was set to 200%.
[0202]
(Preparation of resin fine particle dispersion 1)
330 parts by weight of styrene
n-butyl acrylate 80 parts by weight
Acrylic acid 6 parts by weight
2.3 parts by weight of divinylbenzene
Dodecanethiol 6 parts by weight
4 parts by weight carbon tetrabromide
A solution was prepared by mixing and dissolving the above components (total weight 412.6 g), while 6 g of a nonionic surfactant (manufactured by Kao Corporation, Nonipol 400) and an anionic surfactant (manufactured by Daiichi Kogyo Chemical Co., Ltd.) , Neogen SC) was dissolved in 550 g of ion-exchanged water, and the solution was added thereto, dispersed in a flask, emulsified, and slowly stirred and mixed for 10 minutes, and 50 g of ion-exchanged water in which 5 g of ammonium persulfate was dissolved was added. Next, after the inside of the system was sufficiently purged with nitrogen, the flask was heated to 70 ° C. in an oil bath with stirring, emulsion polymerization was continued for 5 hours, the center diameter was 173 nm, the glass transition temperature was 59 ° C., and Mw 52, An anionic resin particle dispersion 1 containing 500 resin particles was obtained.
[0203]
10 was obtained.
[0204]
(Preparation of magnetic substance dispersion liquid 1)
Magnetic material
(Residual magnetization 4.2 Am²/ Kg, particle size 0.2 μ [0.03-0.1 μm: 15 number%, 0.3 μm or more: 2%])
Silane coupling agent [nC₄H₉Si (OCH₃)₃] 0.2 part treatment, hydrophobicity 25%) 150 parts by weight
10 parts by weight of nonionic surfactant (Niopol 400, manufactured by Kao Corporation)
400 parts by weight of ion-exchanged water
The above components were mixed and dissolved, and dispersed with a homogenizer (Ultra Turrax, manufactured by IKA) for 10 minutes to obtain a magnetic substance dispersion liquid 1 having a central particle diameter of 0.23 μm.
[0205]
(Preparation of magnetic substance dispersion liquid 2)
Magnetic material with different particle size distribution
(Residual magnetization 4.1 Am²/ Kg, particle size 0.2 μ [0.03-0.1 μm: 15 number%, 0.3 μm or more: 9%]
Silane coupling agent [nC₄H₉Si (OCH₃)₃] 0.2 part treatment, hydrophobicity 23%)
Was used in the same manner as in the preparation of the magnetic substance dispersion liquid 1 except that the same amount was used to obtain a magnetic substance dispersion liquid 2 containing colorant particles having a center diameter of 0.23 μm.
[0206]
(Preparation of magnetic substance dispersion liquid 3)
Magnetic material with different particle size distribution
(Remanent magnetization 4.3 Am²/ Kg, particle size 0.2 μ [0.03-0.1 μm: 33 number%, 0.3 μm or more: 9%]
Silane coupling agent [nC₄H₉Si (OCH₃)₃] 0.2 part treatment, hydrophobicity 23%)
Was used in the same manner as in the preparation of the magnetic dispersion 1, except that the same amount of was used to obtain a magnetic dispersion 3 containing colorant particles having a center diameter of 0.23 μm.
[0207]
(Preparation of magnetic substance dispersion liquid 4)
Magnetic material not subjected to hydrophobic treatment
(Residual magnetization 4.2 Am²/ Kg, particle size 0.2 μ [0.03-0.1 μm: 15 number%, 0.3 μm or more: 2%])
Was used in the same manner as in the preparation of the magnetic dispersion 1, except that the same amount was used to obtain a magnetic dispersion 4 containing colorant particles having a center diameter of 0.25 μm.
[0208]
(Preparation of magnetic substance dispersion liquid 5)
Magnetic material with different residual magnetization
(Residual magnetization 15.3 Am²/ Kg, particle size 0.2 μ [0.03-0.1 μm: 10 number%, 0.3 μm or more: 3%]
Silane coupling agent [nC₄H₉Si (OCH₃)₃] 0.2 part treatment, hydrophobicity 26%)
Was used in the same manner as in the preparation of the magnetic substance dispersion liquid 1 except that the same amount was used to obtain a magnetic substance dispersion liquid 5 containing colorant particles having a center diameter of 0.25 μm.
[0209]
(Preparation of release agent dispersion liquid 1)
50 parts by weight of paraffin wax (melting point peak temperature 90 ° C)
5.5 parts by weight of cationic surfactant (Sanisol B50, manufactured by Kao Corporation)
200 parts by weight of ion exchange water
The above-mentioned components were heated to 98 ° C. under pressure and sufficiently dispersed by Ultra Turrax T50 manufactured by IKA. A mold dispersion was obtained.
[0210]
(Preparation of release agent dispersion liquid 2)
As wax
Polyethylene wax (melting point peak temperature 112 ° C)
In the same manner as in the preparation of the release agent dispersion 1, except that the same amount was used, a magnetic substance dispersion 2 containing colorant particles having a center diameter of 0.38 μ was obtained.
[0211]
(Production of Toner 1)
200 parts by weight of resin fine particle dispersion 1
Magnetic material dispersion liquid 1 283 parts by weight
Release agent dispersion 1 64 parts by weight
1.23 parts by weight of polyaluminum chloride
The components were thoroughly mixed and dispersed in a round stainless steel flask with a homogenizer (Ultra Turrax T50, manufactured by IKE), and then heated to a coagulation temperature of 58 ° C while stirring the flask in a heating oil bath. Thereafter, the mixture was kept at 58 ° C. for 60 minutes, and then 30 parts by weight of the resin fine particle dispersion 1 was further added, followed by gentle stirring.
[0212]
Thereafter, the pH in the system was adjusted to 7.0 with a 0.5 Mol / L aqueous sodium hydroxide solution, and then the stainless steel flask was sealed and heated to 80 ° C. while continuing to stir using a magnetic seal. Thereafter, the pH was lowered to 4.0 and maintained for 6 hours. After completion of the reaction, the reaction solution was cooled, filtered, and sufficiently washed with ion-exchanged water, and then subjected to solid-liquid separation by Nutsche suction filtration. Further, the resultant was dispersed again in 3 L of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes.
[0213]
After repeating this washing operation five times, solid-liquid separation was performed by Nutsche suction filtration. Subsequently, vacuum drying was continued for 12 hours, and then hydrophobic silica (hexamethyldisilazane treatment, BET200m²/ G) Toner 1 was obtained by externally adding 1.2 parts. When the particle size of the toner was measured by a Coulter counter, the weight average particle size was 6.6 μm and the average circularity was 0.968. The ratio (B / A) of the content (B) of the iron element to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy was 0.0008, and the transmission electron microscope was used. The number of particles satisfying D / C ≦ 0.02 by cross-sectional observation of the toner using (TEM) was 80% or more.
[0214]
Table 1 shows the physical properties of Toner 1.
[0215]
(Production of Toner 2)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was performed, except that the same amount of release agent dispersion 2 was added, to obtain Toner 2.
[0216]
Table 1 shows the physical properties of Toner 2.
[0217]
(Production of Toner 3)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was carried out except that 290 parts of magnetic dispersion 1 and 255 parts of release agent dispersion 1 were added, to obtain Toner 3.
[0218]
Table 1 shows the physical properties of Toner 3.
[0219]
(Production of Toner 4)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was carried out, except that the same amount of magnetic dispersion liquid 2 was added, to obtain Toner 4.
[0220]
Table 1 shows the physical properties of Toner 4.
[0221]
(Production of Toner 5)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was performed, except that the same amount of the magnetic substance dispersion liquid 3 was added, to obtain Toner 5.
[0222]
Table 1 shows the physical properties of Toner 5.
[0223]
(Production of Toner 6)
In the production of the toner 1, the addition amount of the release agent dispersion 1 was changed to 15.0% by weight in terms of solids, and the addition amount of the colorant dispersion 1 was changed to 4.5% by weight in terms of solids. Toner 6 was obtained in the same manner as in the production of Toner 1 except that the pH in the system was 63 ° C. and the pH in the system at 80 ° C. after the aggregation was stopped was 5.0.
[0224]
(Production of Toner 7)
Toner 7 was obtained by performing the same operation as in Production Example 1 of Toner 1 except that the aggregation temperature was 53 ° C. and the aggregation holding time was 4 hours.
[0225]
Table 1 shows the physical properties of Toner 7.
[0226]
(Production of Toner 8)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was carried out, except that the same amount of magnetic substance dispersion 4 was added, to obtain Toner 8.
[0227]
Table 1 shows the physical properties of Toner 8.
[0228]
(Production of Toner 9)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was carried out except that 780 parts of Magnetic Dispersion 1 were added, to obtain Toner 9.
[0229]
Table 1 shows the physical properties of Toner 9.
[0230]
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was performed, except that 130 parts of the resin dispersion liquid was not additionally added, to obtain Toner 10.
[0231]
Table 1 shows the physical properties of Toner 10.
[0232]
(Manufacture of Toner 11)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was performed, except that 160 parts of the resin dispersion was additionally added, to obtain Toner 11.
[0233]
Table 1 shows the physical properties of Toner 11.
[0234]
(Production of Toner 12)
In the production of Toner 1, the same operation as in Production Example 1 of Toner 1 was carried out, except that the same amount of magnetic substance dispersion liquid 5 was added, to obtain Toner 12.
Table 1 shows the physical properties of Toner 12.
[Outside 3]

[0235]
(Example 1)
Using the toner 1, an image output test of 5,000 sheets was performed in a low-temperature and low-humidity environment (15 ° C., 10% RH) where charging up was most easily performed. As a result, a good image without scattering was obtained even after continuous printing of 5000 sheets. Further, after the toner on the sleeve was removed with air, visual observation revealed that no developer was fixed on the sleeve. Table 2 shows the evaluation results of the image density, fog amount and dot reproducibility by the evaluation methods described later.
[0236]
Similarly, an image extraction test was performed under a high temperature and high humidity environment (32.5 ° C., 85% RH). Table 3 shows the results.
[0237]
<Example 2-9 Comparative Example 1-3>
Using each of the toners 2-12 shown in Table 2, in the same manner as in Example 1, 5,000 images were printed in a low-temperature and low-humidity environment (15 ° C., 10% RH).
[0238]
Table 2 shows the evaluation results of the image density, fog amount and dot reproducibility by the evaluation methods described later.
[0239]
Similarly, an image extraction test was performed under a high temperature and high humidity environment (32.5 ° C., 85% RH). Table 3 shows the results.
[Outside 4]

[0240]
The image evaluation was performed as follows.
[0241]
The abrasion of the photoreceptor and the evaluation of toner fusion were evaluated based on the number of durable sheets on which the image failure due to abrasion or toner fusion, that is, black spots or white spots, occurred on a halftone image where image defects tend to appear. The larger the number of durable sheets before occurrence, the better the durability of the image forming method. When these image defects did not occur, the durability test was continued up to 5000 printed sheets.
[0242]
a) The image density was measured with a Macbeth densitometer RD918 (manufactured by Macbeth).
[0243]
b) Fog was measured using REFLECTMETER MODELTC-6DS manufactured by Tokyo Denshoku Co., Ltd. The filter was calculated using the following equation using a green filter.
[0244]
Fog (reflectance) (%) = Reflectance on standard paper (%) − Reflectance of non-image portion of sample (%)
Fog is a good image if it is 2.0% or less.
[0245]
c) The dot reproducibility was evaluated by performing an image-drawing test using an 80 μm × 50 μm checker pattern shown in FIG. 7 and observing the presence or absence of a defect in a black portion with a microscope.
A: 2 or less defects in 100
B: 3 to 5 defects in 100
C: 6 to 10 defects in 100
D: 11 or more defects in 100
d) The transfer efficiency in the initial stage of the endurance (at the time of 100 sheets) is as follows. When the Macbeth density of the Mylar tape pasted on the paper with the toner before fixing was E and the Macbeth density of the Mylar tape pasted on the unused paper was D, it was approximately calculated by the following equation.
[Outside 5]

[0246]
If the transfer efficiency is 90% or more, there is no problem in the image.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an image forming apparatus using a non-contact developing method.
FIG. 2 is an enlarged view of a developing unit of the image forming apparatus shown in FIG.
FIG. 3 is a diagram illustrating an example of a contact transfer member.
FIG. 4 is a diagram illustrating a pattern of a developing bias of the image forming apparatus.
FIG. 5 is an explanatory diagram of a checker pattern for testing a developing characteristic of a toner.

Claims (27)

A toner containing particles obtained by aggregation and association of at least resin particles and iron oxide,
i) the ratio (B / A) of the iron element content (B) to the carbon element content (A) present on the toner surface measured by X-ray photoelectron spectroscopy is less than 0.001,
ii) When the projected area equivalent diameter of the toner is C and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D,
30% by number or more of toners satisfying the relationship of D / C ≦ 0.02;
Toner characterized in that iii) the intensity of residual magnetization in the toner of the magnetic field 79.6 kA / m (1000 oersted) is ^{0.6~6.2Am 2 / kg (emu / g} ). The toner according to claim 1, wherein the ratio (B / A) is less than 0.0005. The toner according to claim 1, wherein the number of toners satisfying the relationship of D / C ≦ 0.02 is 65% by number or more. 3. The toner according to claim 1, wherein the toner satisfying the relationship of D / C ≦ 0.02 is 75% by number or more. The toner according to any one of claims 1 to 4, wherein the iron oxide is contained in an amount of 10 to 200 parts by mass based on 100 parts by mass of the binder resin. The toner according to any one of claims 1 to 4, wherein the iron oxide is contained in an amount of 20 to 180 parts by mass with respect to 100 parts by mass of the binder resin. 6. The toner according to claim 1, wherein the iron oxide has a hydrophobicity of 5 to 90%. 7. The toner according to claim 1, wherein the toner has a weight average particle diameter of 2 to 10 [mu] m. 7. The toner according to claim 1, wherein the toner has a weight average particle diameter of 3.5 to 8 [mu] m. 8. The toner according to claim 1, wherein the average circularity of the toner is 0.950 or more. 11. The iron oxide according to claim 1, wherein the volume average particle diameter is 0.1 to 0.3 [mu] m, and the number of particles of 0.03 to 0.1 [mu] m is 40% by number or less. Toner. 12. The iron oxide according to claim 11, wherein the iron oxide contains 30% by number or less of particles of 0.03 to 0.1 [mu] m and 10% or less of particles of 0.3 [mu] m or more. toner. 13. The iron oxide according to claim 12, wherein the iron oxide contains not more than 30% by number of particles of 0.03 to 0.1 [mu] m and not more than 5% by number of particles of not less than 0.3 [mu] m. toner. 14. The toner according to claim 1, wherein the toner contains wax in an amount of 0.5 to 50% by mass based on the binder resin. 15. The toner according to claim 14, wherein the wax has a maximum endothermic peak in a range of 40 to 110 [deg.] C. when the temperature is raised, in a DSC curve measured by a differential scanning calorimeter. A charging step of charging the electrostatic image carrier by a charging member to which a voltage is externally applied; an exposure step of forming an electrostatic latent image on the electrostatic image carrier by exposure; Developing with a toner carried on a body to form a toner image; and a transfer step of transferring the toner image to a transfer material, the toner comprising at least resin particles and iron oxide. I) the ratio of the content (B) of the iron element (B) to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy (B / A) is less than 0.001,
ii) When the projected area equivalent diameter of the toner is C and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D,
30% by number or more of toners satisfying the relationship of D / C ≦ 0.02;
image forming method, characterized in that iii) the intensity of residual magnetization in the toner of the magnetic field 79.6 kA / m (1000 oersted) is ^{0.6~6.2Am 2 / kg (emu / g} ). In the developing step, the electrostatic image carrier and the toner carrier are arranged at a fixed interval, and a toner layer is formed on the surface of the toner carrier with a thickness smaller than the interval, and an AC bias is applied. 17. The image forming method according to claim 16, wherein the developing is performed by transferring the toner to an electrostatic latent image in a developing unit. 18. The image forming method according to claim 17, wherein a separation distance between the electrostatic image carrier and the toner carrier is 100 to 500 [mu] m. 19. The image forming method according to claim 17, wherein, in the developing step, a speed difference between the surface of the electrostatic image carrier and the surface of the toner carrier in the developing area is 1.02 to 3.0 times. . 20. The image forming method according to claim 17, wherein the surface roughness Ra of the toner carrier is 0.2 to 3.5 [mu] m. 21. The image forming method according to claim 17, wherein the AC bias has a peak-to-peak electric field intensity of 3 × 10 ⁶ to 1 × 10 ⁷ V / m and a frequency of 100 to 5000 Hz. The image forming method according to any one of claims 16 to 21, wherein the charging step is a step of charging by bringing a charging member into contact with the electrostatic image carrier. The image according to any one of claims 16 to 22, wherein the transfer step is a step of transferring the toner image to the transfer material by a transfer member that contacts the electrostatic image carrier via the transfer material. Forming method. The charging step is a step of charging by bringing the charging member into contact with the electrostatic image carrier, and the developing step is to arrange the electrostatic image carrier and the toner carrier at a predetermined interval, and A step of forming a toner layer on the body surface with a thickness smaller than the interval, and transferring the toner to an electrostatic latent image in a developing unit to which an AC bias is applied to perform development. Item 17. The image forming method according to Item 16. The layer thickness of the toner carried on the toner carrier is regulated by a toner layer thickness regulating member, and the toner layer thickness regulating member is in contact with the toner carrier via the toner. The image forming method according to claim 24, wherein: The image forming method according to claim 25, wherein the toner layer thickness regulating member is an elastic member. The image forming method according to any one of claims 16 to 26, further comprising a fixing step of fixing the toner image transferred to the transfer material to the transfer material.

Images