JP3902943B2 - Developer and image forming method - Google Patents

Description

【００５６】
ここで、「粒子投影面積」とは二値化されたトナー粒子像の面積であり、「粒子投影像の周囲長」とは該トナー粒子像のエッジ点を結んで得られる輪郭線の長さと定義する。
【００５７】
本発明における円形度はトナー粒子の凹凸の度合いを示す指標であり、トナー粒子が完全な球形の場合には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。
【００５８】
本発明において、トナーの個数基準の粒径頻度分布の平均値を意味する円相当個数平均径Ｄ１（μｍ）と粒径標準偏差ＳＤｄは、粒度分布の分割点ｉでの粒径（中心値）をｄｉ、頻度をｆｉとすると次式から算出される。
【００５９】
【数２】

【００６０】

【００６１】
【数３】

【００６２】
具体的な測定方法としては、容器中に予め不純固形物などを除去したイオン交換水１０ｍｌを用意し、その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加えた後、更に測定試料を０．０２ｇを加え、均一に分散させる。分散手段としては、超音波分散機ＵＨ−５０型（エスエムテー社製）に振動子として５φのチタン合金チップを装着したものを用い、５分間分散処理を行い、測定用の分散液とする。その際、該分散液の温度が４０℃以上にならないように適宜冷却する。
【００６３】
トナー粒子の形状測定には、前記フロー式粒子像測定装置を用い、測定時のトナー粒子濃度が３０００〜１万個／μｌとなるように該分散液濃度を再調整し、トナー粒子を１０００個以上計測する。計測後、このデータを用いてトナー粒子の円相当径や円形度頻度分布等を求める。
【００６４】
本発明のトナーのフロー式粒子像測定装置で計測される個数基準の円相当径−円形度スキャッタグラムにおける平均円形度は、０．９５０乃至０．９９９が好ましい。より好ましい平均円形度及び円形度標準偏差は、０．９５０乃至０．９９９でかつ０．０４０未満が好ましく、さらに好ましくは、０．９５０乃至０．９９５であり、０．０１５以上０．０３５未満であることが好ましく、さらに好ましくは０．９７０乃至０．９９５でかつ、０．０１５乃至０．０３５が良い。
【００６５】
平均円形度が０．９５０未満の場合には、トナー形状がかなり不定形になるために、連続通紙時のトナー転写効率が悪くなり、感光体上に転写残トナーがおおく、現像兼回収がし難くなる。
平均円形度が０．９９９を超える場合には、製造面において、再現性、収率が著しく悪化し、コストアップにつながる。
【００６６】
円形度標準偏差が０．０４を超える場合には、トナーの形状分布が拡がるために、均一転写が悪化し、現像兼回収がし難くなる。
【００６７】
以下、実施例の画像形成装置（画像記録装置）について説明する。
【００６８】
図３は本発明に従う画像形成装置例の概略構成模型図である。本例の画像形成装置は、転写方式電子写真プロセス利用、接触帯電方式、反転現像方式、クリーナレス、最大通紙サイズがＡ３サイズのレーザビームプリンタである。
【００６９】
（１）プリンタの全体的概略構成
ａ）感光ドラム
１は回転ドラム型の電子写真感光体（以下、感光ドラムと記す）である。この感光ドラム１は、図４の層構成模型図のように、アルミニウム製シリンダ（導電性ドラム基体）１ａの表面に、光の干渉を抑え、上層の接着性を向上させる下引き層１ｂと、光電荷発生層１ｃと、電荷輸送層１ｄの３層を下から順に塗り重ねた構成をしている。
【００７０】
本発明の感光ドラムは上記に限られるものではない。以下につぎに電子写真感光体の典型的な構成について、図５、図６および図７により説明する。
【００７１】
感光層が有機光導電体を主成分として構成され、有機光導電体としては、ポリビニールカルバゾール等の有機光導電性ポリマーを用いたもの、あるいは低分子量の有機光導電性物質を結着樹脂中に含有したものなどがある。
【００７２】
図５の電子写真感光体は、導電性支持体１６上に感光層１７が設けられており、この感光層１７は結着樹脂中に電荷発生物質１８を分散含有した電荷発生層１９と電荷輸送層２０の積層構造である。この場合電荷輸送層２０は、電荷発生層１９の上に積層されている。
【００７３】
図６の電子写真感光体は、図５の場合と異なり、電荷輸送層２０は電荷発生層１９の下に積層されている。この場合、電荷発生層１９中には電荷輸送物質が含有されていてもよい。
【００７４】
図７の電子写真感光体は、導電性支持体１６上に感光層１７が設けられており、この感光層１７は結着樹脂中に電荷発生物質１８と電荷輸送物質（図示せず）が含有されている。
【００７５】
これらのうち、図５に示すように、導電性支持体１６側から電荷発生層１９、次いで、電荷輸送層２０の順で積層されている構造の感光体が本発明においては好ましい。
【００７６】
導電性支持体１６としては、アルミニウム、ステンレスなどの金属、紙、プラスチックなどの円筒状シリンダー、シートまたはフィルムなどが用いられる。また、これらの円筒状シリンダー、シートまたはフィルムは、必要に応じて導電性ポリマー層、あるいは酸化スズ、酸化チタン、銀粒子などの導電性粒子を含有する樹脂層を有していてもよい。
【００７７】
また、導電性支持体１６と感光層１７の間にはバリアー機能と下引き機能を持つ下引き層（接着層）を設けることができる。
【００７８】
下引き層は感光層の接着性改良、塗工性改良、支持体の保護、支持体の欠陥の被覆、支持体からの電荷注入性改良、感光層の電気的破壊に対する保護などのために形成される。その膜厚は０．２〜２μｍ程度である。
【００７９】
電荷発生物質としては、ピリリウム、チオピオリリウム系染料、フタロシアニン系顔料、アントアントロン顔料、ジベンズビレンキノン顔料、ピラトロン顔料、アゾ顔料、インジゴ顔料、キナクリドン系顔料、非対称キノシアニン、キノシアニンなどを用いることができる。
【００８０】
電荷輸送物質としては、ヒドラゾン系化合物、ピラゾリン系化合物、スチリル系化合物、オキサゾール系化合物、チアゾール系化合物、トリアリールメタン系化合物、ポリアリールアルカン系化合物などを用いることができる。
【００８１】
電荷発生層１９は、上記電荷発生物質を０．５〜４倍量の結着剤樹脂、および溶剤と共に、ホモジナイザー、超音波、ボールミル、振動ボールミル、サンドミル、アトライター、ロールミルなどの方法でよく分散し、塗布、乾燥されて形成される。その厚みは５μｍ以下、特には０．０１〜１μｍの範囲が好ましい。
【００８２】
電荷輸送層２０は、一般的には上記電荷輸送物質と結着剤樹脂を溶剤に溶解し、塗布して形成する。電荷輸送物質と結着剤樹脂との混合割合は２：１〜１：２程度である。溶剤としては、アセトン、メチルエチルケトンなどのケトン類、酢酸メチル、酢酸エチルなどのエステル類、トルエン、キシレンなどの芳香族炭化水素類、クロルベンゼン、クロロホルム、四塩化炭素などの塩素系炭化水素類、などが用いられる。この溶液を塗布する際には、例えば浸漬コーティング法、スプレーコーティング法、スピンナーコーティング法などのコーティング法を用いることができ、乾燥は１０〜２００℃、好ましくは２０〜１５０℃の範囲の温度で５分〜５時間、好ましくは１０分〜２時間で送風乾燥または静止乾燥下で行うことができる。生成した電荷輸送層の膜厚は５〜３０μｍ、特には１０〜２５μｍの範囲が好ましい。
【００８３】
電荷発生層１９および電荷輸送層２０を形成するのに用いられる結着樹脂としては、アクリル樹脂、スチレン系樹脂、ポリエステル、ポリカーボネート樹脂、ポリアリレート、ポリサルホン、ポリフェニレンオキシド、エポキシ樹脂、ポリウレタン樹脂、アルキド樹脂、および不飽和樹脂等から選ばれる樹脂が好ましい。特に好ましい樹脂としては、ポリメチルメタクリレート、ポリスチレン、スチレン−アクリロニトリル共重合体、ポリカーボネート樹脂またはジアリルフタレート樹脂が挙げられる。
【００８４】
また、電荷発生層あるいは電荷輸送層には、酸化防止剤、紫外線吸収剤、潤滑剤など種々の添加剤を含有させることができる。
【００８５】
ｂ）帯電手段
２は感光ドラム１の周面を一様に帯電処理する帯電手段としての接触帯電装置（接触帯電器）であり、本例は帯電ローラ（ローラ帯電器）である。
【００８６】
この帯電ローラ２は、芯金２ａの両端部をそれぞれ不図示の軸受け部材により回転自在に保持させると共に、押し圧ばね２ｅによって感光ドラム方向に付勢して感光ドラム１の表面に対して所定の押圧力をもって圧接させており、感光ドラム１の回転に従動して回転する。感光ドラム１と帯電ローラ２との圧接部が帯電部（帯電ニップ部）ａである。
【００８７】
帯電ローラ２の芯金２ａには電源Ｓ１より所定の条件の帯電バイアス電圧が印加されることにより回転感光ドラム１の周面が所定の極性・電位に接触帯電処理される。本例において、帯電ローラ２に対する帯電バイアス電圧は直流電圧（Ｖｄｃ）と交流電圧（Ｖａｃ）とを重畳した振動電圧である。
【００８８】
直流電圧；−５００Ｖ
交流電圧；周波数ｆ１０００Ｈｚ、ピーク間電圧Ｖｐｐ１３００Ｖ、正弦波とを重畳した振動電圧であり、感光ドラム１の周面は−５００Ｖ（暗電位Ｖｄ）に一様に接触帯電処理される。
【００８９】
帯電ローラ２の長手長さは３２０ｍｍであり、図４の層構成模型図のように、芯金（支持部材）２ａの外回りに、弾性層２ｂと、抵抗制御層２ｃと、表面層２ｄを下から順次に積層した３層構成である。弾性層２ｂは帯電音を低減するための発泡スポンジ層であり、抵抗制御層２ｃは帯電ローラ全体として均一な抵抗を得るための導電層であり、表面層２ｄは感光ドラム１上にピンホール等の欠陥があってもリークが発生するのを防止するために設けている保護層である。
【００９０】
さらに詳細に説明する。
【００９１】
図４において、２は帯電部材、２ａは導電性支持体、２ｂは弾性層、２ｃは抵抗制御層、２ｄは表面層を示す。帯電ローラは抵抗制御層２ｃのない弾性層２ｂと表面層２ｄの構成であってもよい。
【００９２】
本発明に用いられる導電性支持体２ａは、鉄、銅、ステンレス、アルミニウム及びニッケル等の金属を用いることができる。更に、これらの金属表面に防錆や耐傷性付与を目的としてメッキ処理を施しても構わないが、導電性を損なわないことが必要である。
【００９３】
帯電ローラ２において、弾性層２ｂには、帯電ローラ２の感光体１に対する良好な均一密着性を確保するために適当な弾性を持たせてある。
【００９４】
弾性層２ｂの導電性はゴム等の弾性材料中にカーボンブラック等の導電性粒子あるいはアルカリ金属塩及びアンモニウム塩等の導電剤を添加することにより調整される。弾性はプロセス油及び可塑剤等の添加により調整される。弾性層２ｂの具体的弾性材料としては、例えば、天然ゴム、エチレンプロピレンジエンメチレンゴム（ＥＰＤＭ）、スチレン−ブタジエンゴム（ＳＢＲ）、シリコーンゴム、ウレタンゴム、エピクロルヒドリンゴム、イソプレンゴム（ＩＲ）、ブタジエンゴム（ＢＲ）、ニトリル−ブタジエンゴム（ＮＢＲ）及びクロロプレンゴム（ＣＲ）等の合成ゴム、更にはポリアミド樹脂、ポリウレタン樹脂、シリコーン樹脂及びフッ素樹脂等の樹脂も挙げられる。また、前述の弾性材料の発泡体を弾性層２ｂに用いてもよい。
【００９５】
前記弾性層の電気抵抗は、１×１０³〜１×１０¹⁰［Ωｃｍ］の範囲の導電性を有していることが好ましい。また、膜厚は導電性支持体の径にもよるので、特に制限を受けるものではない。
【００９６】
表面層２ｄは弾性層２ｂ中の可塑剤等の帯電ローラ表面へのブリードアウトを防止するためや帯電ローラ表面の滑り性や平滑性を維持するために設けることが多い。表面層２ｄは塗工あるいはチューブを被覆することによって設ける。
【００９７】
表面層２ｄを塗工により設ける場合、具体的な材料としては、ポリアミド樹脂、ポリウレタン樹脂、アクリル樹脂、フッ素樹脂及びシリコーン樹脂等の樹脂、更にはエピクロルヒドリンゴム、ウレタンゴム、クロロプレンゴム及びアクリロニトリル系ゴム等が挙げられる。塗工方法としては、浸漬塗工法、ロール塗工法及びスプレー塗工法などがよい。
【００９８】
また、表面層２ｄをチューブを被覆することにより設ける場合、具体的な材料としては、ナイロン１２、ＰＦＡ（４フッ化エチレン−パーフルオロアルキルビニルエーテル共重合樹脂）、ＰＶＤＦ（ポリフッ化ビニリデン）、ＦＥＰ（４フッ化エチレン−６フッ化プロピレン共重合樹脂）、更にはポリスチレン系、ポリオレフィン系、ポリ塩化ビニル系、ポリウレタン系、ポリエステル系及びポリアミド系等の熱可塑性エラストマーが挙げられる。
【００９９】
チューブは熱収縮性チューブであってもよいし、非熱収縮性チューブであってもよい。表面層２ｄにも適度な導電性を持たせるため、カーボンブラック及びカーボングラファイトのような導電性粒子や、導電性酸化チタン、導電性酸化亜鉛及び導電性酸化錫等の導電性金属酸化物等の導電剤が用いられる。
【０１００】
前記表面層の電気抵抗は、１×１０⁶〜１×１０¹⁴［Ωｃｍ］の範囲であることが好ましい。
【０１０１】
また、膜厚は、２乃至５００μｍであることが好ましい。より好ましくは、２乃至２５０μｍである。
【０１０２】
抵抗制御層２ｃは帯電部材の抵抗を制御するために設けることが多い。抵抗制御層２ｃの具体的材料としては、ポリアミド樹脂、ポリウレタン樹脂、フッ素樹脂、シリコーン樹脂等の樹脂、さらにはエピクロルヒドリンゴム、ウレタンゴム、クロロプレンゴム及びアクリロニトリル系ゴム等が挙げられる。抵抗制御層２ｃにも抵抗調整を目的として、カーボンブラックやカーボングラファイトのような導電性粒子や、導電性酸化チタン、導電性酸化亜鉛及び導電性酸化錫等の導電性金属酸化物あるいはアルカリ金属塩及びアンモニウム塩等の導電剤を分散することができる。
【０１０３】
抵抗制御層２ｃもまた塗工あるいはチューブを被覆することによって設ける。
【０１０４】
前記抵抗制御層の電気抵抗は、１×１０⁶〜１×１０¹⁰［Ωｃｍ］の範囲であることが好ましい。また、膜厚は、１０乃至１０００μｍであることが好ましい。より好ましくは、１０乃至７５０μｍである。
【０１０５】
本発明における体積抵抗率の測定は、ＪＩＳ Ｋ ６９１１に準じて行ったものである。
【０１０６】
図４において、２ｆは帯電ローラクリーニング部材であり、本例では可撓性を持つクリーニングフィルムである。このクリーニングフィルム２ｆは、帯電ローラ２の長手方向に対し平行に配置され且つ同長手方向に対し一定量の往復運動をする支持部材２ｇに一端を固定され、自由端側近傍の面において帯電ローラ２と接触ニップを形成するよう配置されている。支持部材２ｇがプリンタの駆動モーターによりギア列を介して長手方向に対し一定量の往復運動駆動されて帯電ローラ表面層２ｄがクリーニングフィルム２ｆで摺擦される。これにより帯電ローラ表面層２ｄの付着汚染物（微粉トナー、外添剤など）の除去がなされる。
【０１０７】
ｃ）情報書き込み手段
３は帯電処理された感光ドラム１の面に静電潜像を形成する情報書き込み手段としては露光である。ＬＥＤアレイを用いる方法、半導体レーザを用いる方法、液晶シャッタアレイを用いた方法などがある。
【０１０８】
本例は半導体レーザを用いたレーザビームスキャナである。画像読み取り装置等のホスト装置からプリンタ側に送られた画像信号に対応して変調されたレーザ光を出力して回転感光ドラム１の一様帯電処理面を露光位置ｂにおいてレーザ走査露光Ｌ（イメージ露光）する。このレーザ走査露光Ｌにより感光ドラム１面のレーザ光で照射されたところの電位が低下することで回転感光ドラム１面には走査露光した画像情報に対応した静電潜像が順次に形成されていく。
【０１０９】
ｄ）現像手段
４は感光ドラム１上の静電潜像に現像剤（トナー）を供給し静電潜像を可視化する現像手段としての現像装置（現像器）であり、本例は二成分磁気ブラシ現像方式の反転現像装置である。
【０１１０】
４ａは現像容器、４ｂは非磁性の現像スリーブであり、この現像スリーブ４ｂはその外周面の一部を外部に露呈させて現像容器４ａ内に回転可能に配設してある。４ｃは非回転に固定して現像スリーブ４ｂ内に挿設したマグネットローラ、４ｄは現像剤コーティングブレード、４ｅは現像容器４ａに収容した二成分現像剤、４ｆは現像容器４ａ内の底部側に配設した現像剤撹拌部材、４ｇはトナーホッパーであり、補給用トナーを収容させてある。
【０１１１】
而して、回転する現像スリーブ４ｂの面に薄層としてコーティングされ、現像部ｃに搬送された現像剤中のトナー分が現像バイアスによる電界によって感光ドラム１面に静電潜像に対応して選択的に付着することで静電潜像がトナー画像として現像される。本例の場合は感光ドラム１面の露光明部にトナーが付着して静電潜像が反転現像される。
【０１１２】
現像部ｃを通過した現像スリーブ４ｂ上の現像剤薄層は、引き続く現像スリーブの回転に伴い現像容器４ａ内の現像剤溜り部に戻される。
【０１１３】
現像容器４ａ内の二成分現像剤４ｅのトナー濃度を所定の略一定範囲内に維持させるために、現像容器４ａ内の二成分現像剤４ｅのトナー濃度が不図示の例えば光学式トナー濃度センサーによって検知され、その検知情報に応じてトナーホッパー４ｇが駆動制御されて、トナーホッパー内のトナーが現像容器４ａ内の二成分現像剤４ｅに補給される。二成分現像剤４ｅに補給されたトナーは撹拌部材４ｆにより撹拌される。
【０１１４】
ｅ）転写手段・定着手段
５は転写装置であり、本例は転写ローラである。この転写ローラ５は感光ドラム１に所定の押圧力をもって圧接させてあり、その圧接ニップ部が転写部ｄである。この転写部ｄに不図示の給紙機構部から所定の制御タイミングにて転写材（被転写部材、記録材）Ｐが給送される。
【０１１５】
転写部ｄに給送された転写材Ｐは、回転する感光ドラム１と転写ローラ５の間に挟持されて搬送され、その間、転写ローラ５に電源Ｓ３からトナーの正規帯電極性である負極性とは逆極性である正極性の転写バイアス本例では＋２ｋＶが印加されることで、転写部ｄを挟持搬送されていく転写材Ｐの面に感光ドラム１面側のトナー画像が順次に静電転写されていく。
【０１１６】
転写部ｄを通ってトナー画像の転写を受けた転写材Ｐは、回転感光ドラム１面から順次に分離されて定着装置６（例えば熱ローラ定着装置）へ搬送されてトナー画像の定着処理を受けて画像形成物（プリント、コピー）として出力される。
【０１１７】
（２）クリーナレスシステムおよびトナー帯電量制御
本例のプリンタはクリーナレスであり、転写材Ｐに対するトナー画像転写後の感光ドラム１面に若干量残留する転写残トナーを除去する専用のクリーニング装置は具備させていない。転写後の感光ドラム１面上の転写残トナーは、引き続く感光ドラム１の回転に伴い帯電部ａ、露光部ｂを通って現像部ｃに持ち運ばれて、現像装置３により現像兼クリーニング（回収）される（クリーナレスシステム）。
【０１１８】
本実施例においては現像装置４の現像スリーブ４ｂは前述したように現像部ｃにおいて、感光ドラム１面の進行方向とは逆方法に回転させており、これは感光ドラム１上の転写版トナーの回収に有利である。
【０１１９】
感光ドラム１面上の転写残トナーは露光部ｂを通るので露光工程はその転写残トナー上からなされるが、転写残トナーの量は少ないため、大きな影響は現れない。
【０１２０】
ただ前述のように、転写残トナーには帯電極性が正規極性のもの、逆極性のもの（反転トナー）、帯電量が少ないものが混在しており、その内の反転トナーや帯電量が少ないトナーが帯電部ａを通過する際に帯電ローラ２に付着することで帯電ローラが許容以上にトナー汚染して帯電不良を生じることになる。
【０１２１】
また、感光ドラム１面上の転写残トナーの現像装置３による現像兼クリーニングを効果的に行なわせるためには、現像部ｃに持ち運ばれる感光ドラム上の転写残トナーの帯電極性が正規極性であり、かつその帯電量が現像装置によって感光ドラムの静電潜像を現像できるトナーの帯電量であることが必要である。反転トナーや帯電量が適切でないトナーについては感光ドラム上から現像装置に除去・回収できず、不良画像の原因となってしまう。
【０１２２】
そこで本実施例においては、転写部ｄよりも感光ドラム回転方向下流側で、帯電部ａよりも感光ドラム回転方向上流側の位置において、転写残トナーの帯電極性を正規極性である負極性に揃えるためのトナー（現像剤）帯電量制御手段７を設けている。
【０１２３】
転写残トナーの帯電極性を正規極性である負極性に揃えることにより、さらに下流に位置する帯電部ａで、該転写残トナーの上から感光ドラム１面上を帯電処理する際に、感光ドラム１への鏡映力が大きくし、転写残トナーの帯電ローラ２への付着を防止するのである。
【０１２４】
この為に転写残トナーに必要な帯電量は現像時のトナー帯電量と比較すると、２．２倍以上必要である。
【０１２５】
次に本発明のトナーについて説明をする。
【０１２６】
まず外添剤に関する記載を述べる。
【０１２７】
本発明に使用できるトナーの外添剤としては、Ｓｉ原子を主成分とする微粒子としてシリカ，Ｔｉ原子を主成分とする微粒子としてチタニアが好適に用いられる。その他、酸化ジルコニウム，酸化マグネシウムの如き酸化物の他に、炭化ケイ素，チッ化ケイ素，チッ化ホウ素，チッ化アルミニウム，炭酸マグネシウム，有機ケイ素化合物なども併用することが可能である。
【０１２８】
特にシリカは、出発材料あるいは温度等の酸化の条件により、ある程度任意に、一次粒子の合一をコントロールできる点で好ましい。例えば、かかるシリカは硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法またはヒュームドシリカと称される乾式シリカ、及びアルコキシド，水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、またＮａ₂Ｏ，ＳＯ₃ ^2-の如き製造残滓の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム，塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能でありそれらも包含する。
【０１２９】
更に、上記シリカは疎水化処理されていることが、トナーの帯電量の温度や湿度の如き環境依存性を少なくするため及びトナー表面からの過剰な遊離を防止するために良い。この疎水化処理剤としては、例えばシランカップリング剤、チタンカップリング剤、アルミニウムカップリング剤の如きカップリング剤が挙げられる。特にシランカップリング剤が、無機酸化物微粒子上の残存基あるいは吸着水と反応し均一な処理が達成され、トナーの帯電の安定化，流動性付与の点で好ましい。
【０１３０】
シランカップリング剤は、下記一般式
Ｒｍ ＳｉＹｎ
Ｒ：アルコキシ基
ｍ：１〜３の整数
Ｙ：アルキル基
ビニル基、グリシドキシ基、メタクリル基を含む炭化水素基
ｎ：１〜３の整数
で表されるものであり、例えばビニルトリメトキシシラン，ビニルトリエトキシシラン，γ−メタクリルオキシプロピルトリメトキシシラン，ビニルトリアセトキシシラン，メチルトリメトキシシラン，メチルトリエトキシシラン，イソブチルトリメトキシシラン，ジメチルジメトキシシラン，ジメチルジエトキシシラン，トリメチルメトキシシラン，ヒドロキシプロピルトリメトキシシラン，フェニルトリメトキシシラン，ｎ−ヘキサデシルトリメトキシシラン，ｎ−オクタデシルトリメトキシシラン等を挙げることができる。
【０１３１】
より好ましくは、Ｃ_aＨ_2a+1−Ｓｉ（ＯＣ_bＨ_2b+1）₃
ａ＝４〜１２、ｂ＝１〜３である。
【０１３２】
ここで、一般式におけるａが４より小さいと、処理は容易となるが疎水性が十分に達成できない。またａが１２より大きいと疎水性は十分になるが、粒子同士の合一が多くなり、流動性付与能が低下してしまう。
【０１３３】
ｂは３より大きいと反応性が低下して疎水化が十分に行われなくなってしまう。したがって上記一般式におけるａは４〜１２、好ましくは４〜８、ｂは１〜３、好ましくは１〜２が良い。
【０１３４】
その処理量は１００質量部に対して１〜５０質量部、粒子合一させずに均一に処理するために好ましくは３〜４０質量部とし、疎水化度を２０〜９８％、好ましくは３０〜９０％、より好ましくは４０〜８０％にすれば良い。
【０１３５】
Ｔｉ原子を主成分とする微粒子としては、チタニアが好ましい。その製法としては何ら制約はないが、ハロゲン化物あるいはアルコキシドを気相下で酸化する方法、あるいは水存在下で加水分解しながら生成する方法などが使用できる。例えば、アモルファス酸化チタンあるいはアナターゼ型酸化チタン、ルチル型酸化チタンなどを用いることができる。
【０１３６】
本発明のトナーにおいては、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばポリフッ化エチレン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末の如き研磨剤、酸化アルミニウム粉末の如きケーキング防止剤、あるいは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末の如き導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることもできる。
【０１３７】
本発明のトナーを粉砕方法で製造する際に用いられるトナーの結着樹脂としては、ポリスチレン；ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如きスチレン置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体の如きスチレン系共重合体；アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニール、シリコーン樹脂、ポリエステル樹脂、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂等が挙げられる。
【０１３８】
これらの樹脂は、単独で又は混合して使用される。
【０１３９】
結着樹脂の主成分としてはスチレンと他のビニルモノマーとの共重合体であるスチレン共重合体が現像性、定着性の点で好ましい。
【０１４０】
スチレン共重合体のスチレンモノマーに対するコモノマーとしては、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドジテル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、アクリロニトリル、メタクリロニトリル、アクリルアミドのような二重結合を有するモノカルボン酸もしくはその置換体；マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチルのような二重結合を有するジカルボン酸及びその置換体；塩化ビニル、酢酸ビニル、安息香酸ビニルのようなビニルエステル；エチレン、プロピレン、ブチレンのようなエチレン系オレフィン；ビニルメチルケトン、ビニルヘキシルケトンのようなビニルケトン；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルのようなビニルエーテルが挙げられる。これらビニル単量体が単独もしくは２つ以上用いられる。
【０１４１】
スチレン共重合体はジビニルベンゼンの如き架橋剤で架橋されていることがトナーの定着温度領域を広げ、耐オフセット性を向上させる上で好ましい。
【０１４２】
本発明のトナーを重合方法で製造する際に用いられる重合性単量体としては、ラジカル重合が可能なビニル系重合性単量体が用いられる。該ビニル系重合性単量体としては、単官能性重合性単量体或いは多官能性重合性単量体を使用することが出来る。
【０１４３】
単官能性重合性単量体としては、スチレン；α−メチルスチレン、β−メチルスチレン、ο−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、２，４−ジメチルスチレン、ｐ−ｎ−ブチルスチレン、ｐ−ｔｅｒｔ−ブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレン、ｐ−メトキシスチレン、ｐ−フェニルスチレンの如きスチレン誘導体；メチルアクリレート、エチルアクリレート、ｎ−プロピルアクリレート、ｉｓｏ−プロピルアクリレート、ｎ−ブチルアクリレート、ｉｓｏ−ブチルアクリレート、ｔｅｒｔ−ブチルアクリレート、ｎ−アミルアクリレート、ｎ−ヘキシルアクリレート、２−エチルヘキシルアクリレート、ｎ−オクチルアクリレート、ｎ−ノニルアクリレート、シクロヘキシルアクリレート、ベンジルアクリレート、ジメチルフォスフェートエチルアクリレート、ジエチルフォスフェートエチルアクリレート、ジブチルフォスフェートエチルアクリレート、２−ベンゾイルオキシエチルアクリレートの如きアクリル系重合性単量体；メチルメタクリレート、エチルメタクリレート、ｎ−プロピルメタクリレート、ｉｓｏ−プロピルメタクリレート、ｎ−ブチルメタクリレート、ｉｓｏ−ブチルメタクリレート、ｔｅｒｔ−ブチルメタクリレート、ｎ−アミルメタクリレート、ｎ−ヘキシルメタクリレート、２−エチルヘキシルメタクリレート、ｎ−オクチルメタクリレート、ｎ−ノニルメタクリレート、ジエチルフォスフェートエチルメタクリレート、ジブチルフォスフェートエチルメタクリレートの如きメタクリル系重合性単量体；メチレン脂肪族モノカルボン酸エステル；酢酸ビニル、プロピオン酸ビニル、酪酸ビニル、安息香酸ビニル、ギ酸ビニルの如きビニルエステル；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルの如きビニルエーテル；ビニルメチルケトン、ビニルヘキシルケトン、ビニルイソプロピルケトンの如きビニルケトンが挙げられる。
【０１４４】
多官能性重合性単量体としては、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、トリプロピレングリコールジアクリレート、ポリプロピレングリコールジアクリレート、２，２’−ビス（４−（アクリロキシ・ジエトキシ）フェニル）プロパン、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、エチレングリコールジメタクリレート、ジエチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、テトラエチレングリコールジメタクリレート、ポリエチレングリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、１，６−ヘキサンジオールジメタクリレート、ネオペンチルグリコールジメタクリレート、ポリプロピレングリコールジメタクリレート、２，２’−ビス（４−（メタクリロキシ・ジエトキシ）フェニル）プロパン、２，２’−ビス（４−（メタクリロキシ・ポリエトキシ）フェニル）プロパン、トリメチロールプロパントリメタクリレート、テトラメチロールメタンテトラメタクリレート、ジビニルベンゼン、ジビニルナフタリン、ジビニルエーテル等が挙げられる。
【０１４５】
本発明においては、上記した単官能性重合性単量体を単独或いは、２種以上組み合わせて、又は、上記した単官能性重合性単量体と多官能性重合性単量体を組み合わせて使用する。多官能性重合性単量体は架橋剤として使用することも可能である。
【０１４６】
上記した重合性単量体の重合の際に用いられる重合開始剤としては、油溶性開始剤及び／又は水溶性開始剤が用いられる。例えば、油溶性開始剤としては、２，２’−アゾビスイソブチロニトリル、２，２’−アゾビス−２，４−ジメチルバレロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリルの如きアゾ化合物；アセチルシクロヘキシルスルホニルパーオキサイド、ジイソプロピルパーオキシカーボネート、デカノニルパーオキサイド、ラウロイルパーオキサイド、ステアロイルパーオキサイド、プロピオニルパーオキサイド、アセチルパーオキサイド、ｔ−ブチルパーオキシ−２−エチルヘキサノエート、ベンゾイルパーオキサイド、ｔ−ブチルパーオキシイソブチレート、シクロヘキサノンパーオキサイド、メチルエチルケトンパーオキサイド、ジクミルパーオキサイド、ｔ−ブチルヒドロパーオキサイド、ジ−ｔ−ブチルパーオキサイド、クメンヒドロパーオキサイドの如きパーオキサイド系開始剤が挙げられる。
【０１４７】
水溶性開始剤としては、過硫酸アンモニウム、過硫酸カリウム、２，２’−アゾビス（Ｎ，Ｎ’−ジメチレンイソブチロアミジン）塩酸塩、２，２’−アゾビス（２−アミノジノプロパン）塩酸塩、アゾビス（イソブチルアミジン）塩酸塩、２，２’−アゾビスイソブチロニトリルスルホン酸ナトリウム、硫酸第一鉄又は過酸化水素が挙げられる。
【０１４８】
本発明においては、重合性単量体の重合度を制御する為に、連鎖移動剤，重合禁止剤等を更に添加し用いることも可能である。
【０１４９】
本発明のトナーに用いられる架橋剤としては、２個以上の重合可能な二重結合を有する化合物が用いられる。例えば、ジビニルベンゼン、ジビニルナフタレンのような芳香族ジビニル化合物；エチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレートのような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホンの如きジビニル化合物；及び３個以上のビニル基を有する化合物が挙げられる。これらは単独もしくは混合物として用いられる。
【０１５０】
本発明のトナーに用いられる離型剤としては、パラフィンワックス、ポリオレフィンワックス、マイクロクリスタリンワックス、フィッシャートロピッシュワックスの如きポリメチレンワックス、アミドワックス、高級脂肪酸、長鎖アルコール、ケトンワックス、エステルワックス及びこれらのグラフト化合物、ブロック化合物の如き誘導体が挙げられ、必要に応じて蒸留などしても構わない。
【０１５１】
下記一般構造式で示すが特にエステルワックスが好ましい。
【０１５２】
【化１】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基を示し、且つＲ₁とＲ₂との炭素数差が３以上である基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない。）
【０１５３】
【化２】

（式中、ａ及びｂは０〜４の整数を示し、ａ＋ｂは４であり、Ｒ₁は炭素数が１〜４０の有機基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない。）
【０１５４】
【化３】

（式中、ａ及びｂは０〜３の整数を示し、ａ＋ｂは３以下であり、Ｒ₁及びＲ₂は炭素数が１〜４０の有機基を示し、且つＲ₁とＲ₂との炭素数差が３以上である基を示し、Ｒ₃は炭素数が１以上の有機基を示し、ｎ及びｍは０〜４０の整数を示し、ｎとｍが同時に０になることはない。）
【０１５５】
該トナーの半値幅は、ＡＳＴＭ Ｄ３４１８−８２に準拠して測定される。そして１０℃以下であることが好ましく、より好ましくは７℃以下が良い。１０℃を超える場合には、結晶性が高くないことから、離型剤の硬度も軟らかく、感光体や帯電ローラへの汚染を促進させてしまう。
【０１５６】
ここでいう吸熱ピークの半値幅とは、吸熱ピークにおけるベースラインからピークの高さの２分の１の吸熱チャートの温度幅である。
【０１５７】
本発明における離型剤のＤＳＣ吸熱曲線における吸熱ピーク値は、トナー中から離型剤を任意の方法で抽出した後、該抽出したサンプルをＡＳＴＭ Ｄ３４１８−８２に準拠して測定する。
【０１５８】
そして、より好ましくは５０乃至１００℃の値を示す化合物が好ましく、特に、ＤＳＣ曲線の接線離脱温度が４０℃以上の離型剤が一層好ましい。
【０１５９】
測定試料は、２〜１０ｍｇの範囲内で正確に秤量する。これをアルミパン中に入れ、リファレンスとして空のアルミパンを用い、測定温度範囲３０〜１６０℃の間で、昇温温度１０℃／ｍｉｎで、常温常湿下で測定を行う。
【０１６０】
吸熱ピーク値が５０℃未満であると、離型剤の自己凝集力が弱い為に、トナー粒子の内部又は中心部を構成しづらく、トナー粒子の製造時にトナー粒子表面に離型剤が析出し、感光体や帯電ローラを汚染しやすい。
【０１６１】
一方、吸熱ピークが１２０℃を超えると、定着時に離型剤が浸み出しにくく、低温時の定着性や、トナー現像量が多い２次色（レッド、グリーン、ブルー）の定着性が低下する。更に、直接重合方法によりトナー粒子を生成する場合には、重合性単量体組成物中への溶解性が低下し、水系媒体中での重合性単量体組成物のトナー粒子径サイズへの液滴の造粒中に離型剤が析出して造粒が困難となり好ましくない。
【０１６２】
離型剤の分子量としては、重量平均分子量（Ｍｗ）が３００乃至１，５００のものが好ましい。３００未満になると離型剤のトナー粒子表面への露出が生じ易く、現像性が悪化し、高温高湿環境下でのカブリが悪い。また、帯電ローラへの汚染も著しい。１，５００を超えると低温定着性が低下しかつ、ＯＨＴ透明性も悪化する。特に４００乃至１，２５０の範囲のものが好ましい。
【０１６３】
更に、重量平均分子量／数平均分子量の比（Ｍｗ／Ｍｎ）が１．５以下になると、離型剤のＤＳＣ吸熱曲線の極大ピークがよりシャープになり、室温時のトナー粒子の機械的強度が向上し、定着時にはシャープな溶融特性を示す特に優れたトナー物性が得られる。
【０１６４】
離型剤の分子量はＧＰＣにより次の条件で測定される。
【０１６５】
（ＧＰＣ測定条件）
装置 ：ＧＰＣ−１５０Ｃ（ウォーターズ社製）
カラム：ＧＭＨ−ＭＴ３０ｃｍ２連（東ソー社製）
温度 ：１３５℃
溶媒 ：ｏ−ジクロロベンゼン（０．１％アイオノール添加）
流速 ：１．０ｍｌ／ｍｉｎ
試料 ：０．１５％の試料を０．４ｍｌ注入
【０１６６】
以上の条件で測定し、試料の分子量算出にあたっては単分散ポリスチレン標準試料により作成した分子量較正曲線を使用する。さらに、Ｍａｒｋ−Ｈｏｕｗｉｎｋ粘度式から導き出される換算式でポリエチレン換算することによって算出される。
【０１６７】
該離型剤の針入度はＪＩＳ Ｋ２２３５に準拠し測定される。測定温度は２５℃とする。該離型剤の針入度は１５度以下、より好ましくは、８度以下であることが良い。１５度を超える場合には、離型剤を含有するトナーの半値幅が１０℃を超える場合と同様に、感光体や帯電ローラへの汚染を促進させてしまう。
【０１６８】
離型剤は、溶融混練粉砕法によりトナー粒子を生成する場合は、結着樹脂１００質量部に対して１乃至１０質量部使用するのが良い。
【０１６９】
重合性単量体組成物を使用して、水系媒体中で直接的にトナー粒子を生成する場合には、重合性単量体１００質量部に対して５乃至４０質量部（より好ましくは、５乃至３０質量部）配合し、結果として、重合性単量体から生成された結着樹脂１００質量部当り離型剤５乃至４０質量部（より好ましくは、５乃至３０質量部）トナー粒子に含有されるのが良い。
【０１７０】
溶融混練粉砕法による乾式トナー製法に比べ重合法によるトナー製法においては、トナー粒子内部に極性樹脂により多量の離型剤を内包化させ易いので乾式トナー製法と比較し、一般に多量の離型剤を用いることが可能となり、定着時のオフセット防止効果には特に有効となる。
【０１７１】
本発明のトナーに用いられる着色剤は、黒色着色剤としてカーボンブラック，磁性体，以下に示すイエロー／マゼンタ／シアン着色剤を用い黒色に調色されたものが利用される。
【０１７２】
イエロー着色剤としては、顔料系としては、縮合アゾ化合物，イソインドリノン化合物，アンスラキノン化合物、アゾ金属錯体メチン化合物、アリルアミド化合物に代表される化合物が用いられる。具体的には、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ３．７．１０．１２．１３．１４．１５．１７．２３．２４．６０．６２．７４．７５．８３．９３．９４．９５．９９．１００．１０１．１０４．１０８．１０９．１１０．１１１．１１７．１２３．１２８．１２９．１３８．１３９．１４７．１４８．１５０．１６６．１６８．１６９．１７７．１７９．１８０．１８１．１８３．１８５．１９１：１．１９１．１９２．１９３．１９９等が好適に用いられる。染料系としては、例えば、Ｃ．Ｉ．ｓｏｌｖｅｎｔＹｅｌｌｏｗ３３．５６．７９．８２．９３．１１２．１６２．１６３、Ｃ．Ｉ．ｄｉｓｐｅｒｓｅ Ｙｅｌｌｏｗ４２．６４．２０１．２１１などが挙げられる。
【０１７３】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物，アントラキノン，キナクリドン化合物，塩基染料レーキ化合物，ナフトール化合物，ベンズイミダゾロン化合物，チオインジゴ化合物，ペリレン化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１２２、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４、Ｃ．Ｉ．ピグメントバイオレッド１９が特に好ましい。
【０１７４】
シアン着色剤としては、フタロシアニン化合物及びその誘導体，アントラキノン化合物，塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６等が特に好適に利用される。
【０１７５】
これらの着色剤は、単独又は混合し更には固溶体の状態で用いることができる。本発明の着色剤は、色相角，彩度，明度，耐侯性，ＯＨＰ透明性，トナー中への分散性の点から選択される。該着色剤の添加量は、樹脂１００質量部に対し１乃至２０質量部添加して用いられる。
【０１７６】
本発明のトナーは、荷電制御剤を併用しても構わない。
【０１７７】
トナーを負荷電性に制御するものとして下記物質がある。
【０１７８】
例えば、有機金属化合物、キレート化合物が有効であり、モノアゾ金属化合物、アセチルアセトン金属化合物、芳香族オキシカルボン酸、芳香族ダイカルボン酸、オキシカルボン酸及びダイカルボン酸系の金属化合物がある。他には、芳香族オキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類などがある。
【０１７９】
さらに、尿素誘導体、含金属サリチル酸系化合物、含金属ナフトエ酸系化合物、ホウ素化合物、４級アンモニウム塩、カリックスアレーン、樹脂系帯電制御剤等が挙げられる。
【０１８０】
トナーを正荷電性に制御するものとして下記物質がある。
【０１８１】
ニグロシン及び脂肪酸金属塩等によるニグロシン変性物、グアニジン化合物、イミダゾール化合物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートの如き４級アンモニウム塩、及びこれらの類似体であるホスホニウム塩の如きオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドの如きジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートの如きジオルガノスズボレート類、樹脂系帯電制御剤等が挙げられる。これらを単独で或いは２種類以上組合せて用いることができる。
【０１８２】
荷電制御剤は、結着樹脂１００質量部当り、０．０１乃至２０質量部、より好ましくは０．５乃至１０質量部使用するのが良い。
【０１８３】
本発明のトナーが重合法トナーの場合に縮合系樹脂を添加しても良い。
【０１８４】
本発明の該縮合系樹脂は例えば、ポリエステル、ポリカーボネート、フェノール樹脂、エポキシ樹脂、ポリアミド、セルロースなどが挙げられる。より好ましくは材料の多様性からポリエステルが望まれる。結着樹脂１００質量部当り、０．０１乃至２０質量部、より好ましくは０．５乃至１０質量部使用するのが良い。
【０１８５】
トナーにおける各種の特性向上を目的とした添加剤としては、耐久性の点から、トナー粒子の体積平均径の１／２以下の粒径であることが好ましい。添加剤の粒径とは、電子顕微鏡におけるトナー粒子の表面観察により求めたその平均粒径を意味する。これら特性付与を目的とした添加剤としては、たとえば、以下のようなものが用いられる。
【０１８６】
流動性付与剤としては、金属酸化物（酸化ケイ素、酸化アルミニウム、酸化チタンなど）カーボンブラック、フッ化カーボンなどが挙げられる。それぞれ、疎水化処理を行ったものが、より好ましい。
【０１８７】
研磨剤としては、金属酸化物（チタン酸ストロンチウム、酸化セリウム、酸化アルミニウム、酸化マグネシウム、酸化クロムなど）・窒化物（窒化ケイ素など）・炭化物（炭化ケイ素など）・金属塩（硫酸カルシウム、硫酸バリウム、炭酸カルシウムなど）が挙げられる。
【０１８８】
滑剤としては、フッ素系樹脂粉末（フッ化ビニリデン、ポリテトラフルオロエチレンなど）・脂肪酸金属塩（ステアリン酸亜鉛、ステアリン酸カルシウムなど）などが挙げられる。
【０１８９】
荷電制御性粒子としては、金属酸化物（酸化錫、酸化チタン、酸化亜鉛、酸化ケイ素、酸化アルミニウムなど）・カーボンブラックなどが挙げられる。
【０１９０】
これら添加剤は、トナー粒子１００質量部に対し、０．１乃至１０質量部が用いられ、好ましくは０．１乃至５質量部が用いられる。
【０１９１】
これら添加剤は、単独で用いても、また、複数併用しても良い。さらに必要に応じ疎水化処理（オイル、カップリング）をしても構わない。
【０１９２】
以下に本発明のトナー製造方法を示す。
【０１９３】
本発明のトナーが粉砕法トナーである場合には、少なくとも結着樹脂、着色剤を、加圧ニーダーやエクストルーダー、或いはメディア分散機等を用いて混練、均一に分散せしめた後、機械的又はジェット気流下でターゲットに衝突させて所望のトナー粒径に微粉砕化せしめ、更に分級工程を経た後、機械的手段を用いて所望の円形度にするしトナー粒子を製造する製造方法や、上記微粉砕化の後に湿式あるいは乾式の熱球形化処理をする方法などがある。
【０１９４】
本発明のトナーが重合法である場合には、特に制約を受けるものではないが、特公昭３６−１０２３１号公報、特開昭５９−５３８５６号公報、特開昭５９−６１８４２号公報に述べられている懸濁重合法を用いて直接トナーを生成する方法；単量体には可溶で水溶性重合開始剤の存在下で直接重合させてトナー粒子を生成するソープフリー重合法に代表される乳化重合法によるトナー粒子の製造が挙げられる。また、マイクロカプセル製法のような界面重合法、ｉｎ−ｓｉｔｕ重合法、コアセルベーション法などの製造も挙げられる。さらに、特開昭６２−１０６４７３号公報や特開昭６３−１８６２５３号公報に開示されている様な、少なくとも１種以上の微粒子を凝集させ所望の粒径のものを得る界面会合法なども挙げられる。
【０１９５】
小粒径のトナー粒子が容易に得られる懸濁重合方法が特に好ましい。さらに一旦得られた重合粒子に更に単量体を吸着せしめた後、重合開始剤を用い重合せしめるシード重合方法も本発明に好適に利用することができる。このとき、吸着せしめる単量体中に、極性を有する化合物を分散あるいは溶解させて使用することも可能である。
【０１９６】
縣濁重合をする場合には、通常単量体組成物１００質量部に対して水３００乃至３０００質量部を分散媒体として使用するのが好ましい。用いる分散剤として例えば無機系酸化物として、リン酸三カルシウム，リン酸マグネシウム，リン酸アルミニウム，リン酸亜鉛，炭酸カルシウム，炭酸マグネシウム，水酸化カルシウム，水酸化マグネシウム，水酸化アルミニウム，メタケイ酸カルシウム，硫酸カルシウム，硫酸バリウム，ベントナイト，シリカ，アルミナ，ドデシル硫酸ナトリウム等が挙げられる。有機系化合物としては例えばポリビニルアルコール，ゼラチン，メチセルロース，メチルヒドロキシプロピルセルロース，エチルセルロース，カルボキシメチルセルロースのナトリウム塩，デンプン等が使用されている。これら分散剤あるいは分散助剤は、重合性単量体１００質量部に対して０．１乃至５．０質量部を使用することが好ましい。これら分散剤の微細化のために０．００１乃至０．１質量％の界面活性剤を併用しても良い。具体的には市販のノニオン，アニオン，カチオン型の界面活性剤が利用できる。例えばドデシル硫酸ナトリウム，テトラデシル硫酸ナトリウム，ペンタデシル硫酸ナトリウム，オクチル硫酸ナトリウム，オレイン酸ナトリウム，ラウリル酸ナトリウム，ステアリン酸カリウム，オレイン酸カルシウム等が好ましく用いられる。
【０１９７】
次に本発明のキャリアについて説明をする。
【０１９８】
本発明のキャリア粒子の体積基準の５０％粒径及び粒度分布の測定方法は、シンパテック（ＳＹＮＰＡＴＥＣ）社製で乾式分散機（ロドス＜ＲＯＤＯＳ＞）を備えたレーザー回折式粒度分布測定装置（へロス＜ＨＥＬＯＳ＞）を用いて、フィードエア圧力３ｂａｒ、吸引圧力０．１ｂａｒの条件で測定した。
【０１９９】
キャリア粒径は、体積基準による５０％粒径（Ｄ）が好ましくは１５〜６０μｍ、より好ましくは２５〜５０μｍであることがよい。さらにキャリアは、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が、好ましくは５体積％以下、より好ましくは０．１〜５体積％以下であることが良い。
【０２００】
キャリアの５０％粒径が１５μｍ未満である場合には、キャリアの粒度分布の微粒子側の粒子による非画像部へのキャリア付着を良好に防止できず、それが原因で帯電ローラの表面層に傷をつけ、その結果帯電ローラ汚染が生じてしまう場合がある。キャリアの５０％粒径が６０μｍより大きい場合には、トナーへの帯電付与能が低下し、現像特性が劣る場合がある。
【０２０１】
本発明のキャリアの粒度分布として、５０％粒径の２／３以下の粒径の粒子の含有量が５体積％を超える場合には、キャリアの微粉によるキャリア付着を生じる傾向があり、それが原因で帯電ローラの表面層に傷をつけ、その結果帯電ローラ汚染が生じてしまう場合がある。
【０２０２】
本発明において、キャリアの比抵抗は、１×１０⁸〜１×１０¹⁶Ω・ｃｍであることが好ましく、より好ましくは、１×１０⁹〜１×１０¹⁵Ω・ｃｍであることが良い。
【０２０３】
キヤリアの比抵抗が１×１０⁸Ω・ｃｍ未満であると、感光体表面へのキャリア付着を起こし易く、感光体に傷を生じさせたり、直接紙上に転写されたりして画像欠陥を起こし易くなる。さらに、現像バイアスが、キャリアを介してリークし、感光体ドラム上に描かれた静電潜像を乱してしまうことがある。
【０２０４】
キヤリアの比抵抗が１×１０¹⁶Ω・ｃｍを超えると、エッジ強調のきつい画像が形成され易く、さらに、キャリア表面の電荷がリークしづらくなるため、チャージアップ現象による画像濃度の低下や、新たに補給されたトナーへの帯電付与ができなくなくなることによるカブリ及び飛散などを起こしてしまうことがある。さらに、現像器内壁等の物質と帯電してしまい、本来与えられるべきトナーの帯電量が不均一になってしまうこともある。その他、静電気的な外添剤付着など、画像欠陥を引き起こしやすい。
【０２０５】
キャリアの比抵抗の測定は、真空理工（株）社製の粉体用絶縁抵抗測定器を用いて測定した。測定条件は、２３℃，６０％条件下に２４時間以上放置したキャリアを直径２０ｍｍ（０．２８３ｃｍ²）の測定セル中にいれ、１２０ｇ／ｃｍ²の荷重電極で挟み、厚みを２ｍｍとし、印加電圧を５００Ｖで測定した。
【０２０６】
キャリアの磁気特性は、１０００／４π（ｋＡ／ｍ）での磁化の強さが、好ましくは２０〜１００（Ａｍ²／ｋｇ）、より好ましくは３０〜６５（Ａｍ²／ｋｇ）であるような低磁気力であることが良い。
【０２０７】
キャリアの磁化の強さが１００（Ａｍ²／ｋｇ）を超えるとキャリア粒径にも関係するが、現像極での現像スリーブ上に形成される磁気ブラシの密度が減少し、穂長が長くなり、かつ剛直化してしまうためコピー画像上に掃き目ムラが生じやすく、特に多数枚の複写又はプリントによるトナーの耐久劣化が生じやすい。
【０２０８】
キャリアの磁化の強さが２０（Ａｍ²／ｋｇ）未満では、キャリア微粉を除去してもキャリアの磁気力が低下し、キャリア付着が生じやすく、トナー搬送性が低下し易い。
【０２０９】
キャリアの磁気特性の測定は、理研電子（株）製の振動磁場型磁気特性自動記録装置ＢＨＶ−３５を用いて行なった。測定条件としては、キャリア粉体の磁気特性は１０００／４π（ｋＡ／ｍ）の外部磁場を作り、そのときの磁化の強さを求めた。キャリアを円筒状のプラスチック容器にキャリア粒子が動かないように十分密になるようにパッキングした状態に作製し、この状態で磁化モーメントを測定し、試料を入れたときの実際の重量を測定して、磁化の強さ（Ａｍ²／ｋｇ）を求めた。
【０２１０】
本発明において、キャリアコアに用いる金属化合物粒子としては、下記式（１）又は（２）で表される磁性を有するマグネタイト又はフェライトが挙げられる。
ＭＯ・Ｆｅ₂Ｏ₃ ・・・（１）
Ｍ・Ｆｅ₂Ｏ₄ ・・・（２）
（式中、Ｍは３価、２価又は１価の金属イオンを示す。）
【０２１１】
Ｍとしては、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｓｒ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｃｄ、Ｓｎ、Ｂａ、Ｐｂ及びＬｉが挙げられ、これらは、単独あるいは複数で用いることができる。
【０２１２】
上記の磁性を有する金属化合物粒子の具体的化合物としては、例えば、マグネタイト、Ｚｎ−Ｆｅ系フェライト、Ｍｎ−Ｚｎ−Ｆｅ系フェライト、Ｎｉ−Ｚｎ−Ｆｅフェライト、Ｍｎ−Ｍｇ−Ｆｅ系フェライト、Ｃａ−Ｍｎ−Ｆｅ系フェライト、Ｃａ−Ｍｇ−Ｆｅ系フェライト、Ｌｉ−Ｆｅ系フェライト及びＣｕ−Ｚｎ−Ｆｅ系フェライトの如き鉄系酸化物が挙げられる。
【０２１３】
さらに、本発明において、キャリアコアに用いる金属化合物粒子としては、上記の磁性を有する金属化合物と下記の非磁性の金属化合物とを混合して用いても良い。
【０２１４】
非磁性の金属化合物としては、例えば、Ａｌ₂Ｏ₃、ＳｉＯ₂、ＣａＯ、ＴｉＯ₂、Ｖ₂Ｏ₅、ＣｒＯ、ＭｎＯ₂、α−Ｆｅ₂Ｏ₃、ＣｏＯ、ＮｉＯ、ＣｕＯ、ＺｎＯ、ＳｒＯ、Ｙ₂Ｏ₃及びＺｒＯ₂が挙げられる。この場合、１種類の金属化合物を用いることもできるが、とくに好ましくは少なくとも２種以上の金属化合物を混合して用いるのが良い。その場合には、比重や形状が類似している粒子を用いるのが結着樹脂との密着性及びキャリアコア粒子の強度を高めるためにより好ましい。
【０２１５】
組み合わせの具体例としては、例えば、マグネタイトとヘマタイト、マグネタイトとｒ−Ｆｅ₂Ｏ₃、マグネタイトとＳｉＯ₂、マグネタイトとＡｌ₂Ｏ₃、マグネタイトとＴｉＯ₂、マグネタイトとＣａ−Ｍｎ−Ｆｅ系フェライト、マグネタイトとＣａ−ＭｇＦｅ系フェライトが好ましく用いることができる。中でもマグネタイトとヘマタイトの組み合わせが特に好ましく用いることができる。
【０２１６】
上記の磁性を示す金属化合物を単独で使用する場合、又は非磁性の金属化合物と混合して使用する場合、磁性を示す金属化合物の個数平均粒径は、キャリアコアの個数平均粒径によっても変わるが、好ましくは０．０２〜２μｍ、より好ましくは０．０５〜１μｍであることが良い。
【０２１７】
磁性を示す金属化合物の個数平均粒径が０．０２μｍ未満の場合には、好ましい磁気特性を得られがたくなる。磁性を示す金属化合物の個数平均粒径が２μｍを超える場合には、造粒不均一により、強度の高い好ましい粒径のキャリアが得られがたくなる。
【０２１８】
磁性を有する金属化合物と非磁性の化合物とを混合して用いる場合、非磁性の金属化合物の個数平均粒径は、好ましくは０．０５〜５μｍ、より好ましくは０．１〜３μｍであることが良い。この場合、磁性を有する金属化合物の個数平均粒径（平均粒径ｒａ）と、非磁性の金属化合物の個数平均粒径（平均粒径ｒｂ）との粒径比（ｒｂ／ｒａ）は、好ましくは１．０乃至５．０より好ましくは１．２乃至５．０であることが良い。
【０２１９】
非磁性の金属化合物の個数平均粒径が０．０５μｍ未満の場合には、好ましい抵抗が得られず、キャリア付着しやすくなる。非磁性の金属化合物の個数平均粒径が５μｍを超える場合には、造粒不均一により強度の高い好ましい粒径のキャリアが得られがたくなる。
【０２２０】
さらに、ｒｂ／ｒａが１．０未満であると、比抵抗の低い強磁性を示す金属化合物粒子が表面に出やすくなり、キャリアコアの比抵抗を上げにくく、キャリア付着を防止する効果が得られ難くなる。ｒｂ／ｒａが５を超えると、キャリアの強度が低下しやすく、キャリア破壊を引き起こしやすくなる。
【０２２１】
上記金属酸化物の個数平均粒径は、日立製作所（株）製の透過型電子顕微鏡Ｈ−８００により５０００〜２００００倍に拡大した写真画像を用い、ランダムに粒径０．０１μｍ以上の粒子を３００個以上抽出し、ニレコ社（株）製の画像処理解析装置Ｌｕｚｅｘ３により水平方向フェレ径をもって金属酸化物粒径として測定し、平均化処理して個数平均粒径を算出した。
【０２２２】
結着樹脂に分散されている金属化合物の比抵抗は、磁性を有する金属化合物粒子の比抵抗が１×１０³Ω・ｃｍ以上の範囲のものが好ましく、特に、磁性を有する金属化合物と非磁性の化合物とを混合して用いる場合には、磁性を有する金属化合物粒子の比抵抗が１×１０³Ω・ｃｍ以上の範囲が好ましく、他方の非磁性の金属化合物粒子は磁性金属化合物粒子よりも高い比抵抗を有するものを用いることが好ましく、好ましくは本発明に用いる非磁性の金属化合物の比抵抗は１×１０⁸Ω・ｃｍ以上、より好ましくは１×１０¹⁰Ω・ｃｍ以上のものが良い。
【０２２３】
磁性を有する金属化合物粒子の比抵抗が１×１０³Ω・ｃｍ未満であると、含有量を減量しても所望の高比抵抗が得られ難く、電荷注入を招き、画質の劣化や、キャリア付着を招きやすい。また、磁性を有する金属化合物と非磁性の化合物とを混合して用いる場合には、非磁性の金属化合物の比抵抗が１×１０⁸Ω・ｃｍ未満であると、磁性キャリアコアの比抵抗が低くなり、本発明の効果が得られにくくなる。
【０２２４】
本発明において、磁性を有する金属化合物及び非磁性の金属化合物の比抵抗測定方法は、キャリア粒子の比抵抗の測定方法に準じて行なう。
【０２２５】
本発明のキャリアコアにおいて、金属化合物の含有量は、キャリアコアに対して、好ましくは８０〜９９質量％であることが良い。
【０２２６】
金属化合物の含有量が８０質量％未満であると、帯電性が不安定になりやすく、特に低温低湿環境下においてキャリアが帯電し、その残留電荷が残存し易くなるために、微粉トナーや外添剤がキャリア粒子表面に付着し易くなり、さらに、適度な比重が得られなくなる。金属化合物の含有量が９９質量％を超えると、キャリア強度が低下して、耐久によるキャリアの割れなどの問題を生じ易くなる。
【０２２７】
さらに本発明の好ましい形態としては、磁性を有する金属化合物と非磁性の化合物との混合物を含有するキャリアコアにおいて、含有する金属化合物全体に占める磁性を有する金属化合物の含有量が好ましくは５０〜９５質量％、より好ましくは５５〜９５質量％であることが良い。
【０２２８】
含有する金属化合物全体に占める磁性を有する金属化合物の含有量が５０質量％未満であると、コアの高抵抗化は良好になる反面、キャリアとしての磁気力が小さくなり、キャリア付着を招く場合がある。含有する金属化合物全体に占める磁性を有する金属化合物の含有量が９５質量％を超えると、磁性を有する金属化合物の比抵抗にもよるが、より好ましいコアの高抵抗化が図れない場合がある。
【０２２９】
本発明に用いるキャリアコア粒子の結着樹脂としては、熱硬化性樹脂であり、一部または全部が３次元的に架橋されている樹脂であることが好ましい。このことにより、分散する金属化合物粒子を強固に結着できるため、キャリアコアの強度を高めることができ、多数枚の複写においても金属化合物の脱離が起こり難くする。
【０２３０】
磁性体分散型キャリアコアを得る方法としては、特に以下に記載する方法に限定されるものではないが、本発明においては、モノマーと溶媒が均一に分散又は溶解されているような溶液中から、モノマーを重合させることにより粒子を生成する重合法の製造方法、特に、キャリアコア粒子中に分散する金属酸化物に、親油化処理を施すことにより、粒度分布のシャープな、微粉の少ない磁性体分散型樹脂キャリアコアを得る方法が、好適に用いられる。
【０２３１】
本発明においては、高画質化を達成するために重量平均粒径が１〜１０μｍの小粒径トナーと組み合わせて用いられるキャリアの場合、キャリア粒径もトナーの粒径に応じて小粒径化することが好ましく、上述した製造方法ではキャリア粒径を小粒径化させても平均粒径に関係なく微粉の少ないキャリアを製造できることから特に好ましい。
【０２３２】
キャリアコア粒子の結着樹脂に使用されるモノマーとしては、ラジカルの重合性モノマーを用いることができる。例えばスチレン；ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メトキシスチレン、ｐ−エチルスチレン、ｐ−ターシャリーブチルスチレンの如きスチレン誘導体；アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチル、アクリル酸ｎ−プロピル、アクリル酸イソブチル、アクリル酸オクチル、アクリル酸ドデシル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸２−クロルエチル、アクリル酸フェニルの如きアクリル酸エステル；メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、メタクリル酸２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸フェニル、メタクリル酸ジメチルアミノメチル、メタクリル酸ジエチルアミノエチル、メタクリル酸ベンジルの如きメタクリル酸エステル類；２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート；アクリロニトリル、メタクリロニトリル、アクリルアミド；メチルビニルエーテル、エチルビニルエーテル、プロピルビニルエーテル、ｎ−ブチルエーテル、イソブチルエーテル、β−クロルエチルビニルエーテル、フェニルビニルエーテル、ｐ−メチルフェニルエーテル、ｐ−クロルフェニルエーテル、ｐ−ブロムフェニルエーテル、ｐ−ニトロフェニルビニルエーテル、ｐ−メトキシフェニルビニルエーテルの如きビニルエーテル；ブタジエンの如きジエン化合物を挙げることができる。
【０２３３】
これらのモノマーは単独または混合して使用することができ、好ましい特性が得られるような好適な重合体組成を選択することができる。
【０２３４】
前述したように、キャリアコア粒子の結着樹脂は３次元的に架橋されていることが好ましいが、結着樹脂を３次元的に架橋させるための架橋剤としては、重合性の２重結合を一分子当たり２個以上有する架橋剤を使用することが好ましい。このような架橋剤としては、例えば、ジビニルベンゼン、ジビニルナフタレンの如き芳香族ジビニル化合物；エチレングリコールジアクリレート、エチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、テトラエチレングリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、トリメチロールプロパントリアクリレート、トリメチロールプロパントリメタクリレート、１，４−ブタンジオールジアクリレート、ネオペンチルグリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、ペンタエリスリトールジメタクリレート、ペンタエリスリトールテトラメタクリレート、グリセロールアクロキシジメタクリレート、Ｎ，Ｎ−ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド及びジビニルスルフォンが挙げられる。これらは、２種類以上を適宜混合して使用しても良い。架橋剤は、重合性混合物にあらかじめ混合しておくこともできるし、必要に応じて適宜重合の途中で添加することもできる。
【０２３５】
その他のキャリアコア粒子の結着樹脂のモノマーとして、エポキシ樹脂の出発原料としてなるビスフェノール類とエピクロルヒドリン；フェノール樹脂のフェノール類とアルデヒド類；尿素樹脂の尿素とアルデヒド類；メラミンとアルデヒド類が挙げられる。
【０２３６】
もっとも好ましい結着樹脂は、フェノール系樹脂である。その出発原料としては、フェノール、ｍ−クレゾール、３，５−キシレノール、ｐ−アルキルフェノール、レゾルシル、ｐ−ｔｅｒｔ−ブチルフェノールの如きフェノール化合物、ホルマリン、パラホルムアルデヒド、フルフラールの如きアルデヒド化合物が挙げられる。特にフェノールとホルマリンの組み合わせが好ましい。
【０２３７】
これらのフェノール樹脂又はメラミン樹脂を用いる場合には、硬化触媒として塩基性触媒を用いることができる。塩基性触媒として通常のレゾール樹脂製造に使用される種々のものを用いることができる。具体的にはアンモニア水、ヘキサメチレンテトラミン、ジエチルトリアミン、ポリエチレンイミンの如きアミン類を挙げることができる。
【０２３８】
本発明において、キャリアコアに含有される金属化合物は、親油化処理されていることが磁性キャリア粒子の粒度分布をシャープにすること及び金属化合物粒子のキャリアからの脱離を防止する上で好ましい。親油化処理された金属化合物を分散させたキャリアコア粒子を形成する場合、モノマーと溶媒が均一に分散又は溶解している液中から重合反応が進むと同時に溶液に不溶化した粒子が生成する。そのときに金属酸化物が粒子内部で均一に、かつ高密度に取り込まれる作用と粒子同士の凝集を防止し粒度分布をシャープ化する作用があると考えられる。更に、親油化処理を施した金属化合物を用いた場合、フッ化カルシウムの如き懸濁安定剤を用いる必要がなく、懸濁安定剤がキャリア表面に残存することによる帯電性阻害、コート時におけるコート樹脂の不均一性、シリコーン樹脂の如き反応性樹脂をコートした場合における反応阻害を防止することができる。
【０２３９】
親油化処理は、エポキシ基、アミノ基及びメルカプト基から選ばれた、１種又は２種以上の官能基を有する有機化合物や、それらの混合物である親油化処理剤で処理されていることが好ましい。
【０２４０】
磁性金属酸化物粒子は、磁性金属酸化物粒子１００質量部当り好ましくは０．１〜１０質量部、より好ましくは０．２〜６質量部の親油化処理剤で処理されているのが磁性金属酸化物粒子の親油性及び疎水性を高める上で好ましい。
【０２４１】
エポキシ基を有する親油化処理剤としては、γ−グリシドキシプロピルメチルジエトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、β−（３，４−エポキシシクロヘキシル）トリメトキシシラン、エピクロルヒドリン、グリシドール及びスチレン−（メタ）アクリル酸グリシジル共重合体が挙げられる。
【０２４２】
アミノ基を持つ親油化処理剤としては、例えば、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルメトキシジエトキシシラン、γ−アミノプロピルトリエトキシシラン、エチレンジアミン、エチレントリアミン、スチレン−（メタ）アクリル酸ジメチルアミノエチル共重合体及びイソプロピルトリ（Ｎ−アミノエチル）チタネート等が用いられる。
【０２４３】
メルカプト基を有する親油化処理剤としては、例えば、メルカプトエタノール、メルカプトプロピオン酸及びγ−メルカプトプロピルトリメトキシシランが用いられる。
【０２４４】
キャリアコア表面を被覆する樹脂は、特に限定を受けるものではない。具体的には、例えば、ポリスチレン、スチレン−アクリル共重合体の如きアクリル樹脂、塩化ビニル、酢酸ビニル、ポリフッ化ビニリデン樹脂、フルオロカーボン樹脂、パーフロロカーボン樹脂、溶剤可溶性パーフロロカーボン樹脂、ポリビニルアルコール、ポリビニルアセタール、ポリビニルピロリドン、石油樹脂、セルロース、セルロース誘導体、ノボラック樹脂、低分子量ポリエチレン、飽和アルキルポリエステル樹脂、芳香族ポリエステル樹脂、ポリアミド樹脂、ポリアセタール樹脂、ポリカーボネート樹脂、ポリエーテルスルホン樹脂、ポリスルホン樹脂、ポリフェニレンサルファイド樹脂、ポリエーテルケトン樹脂、フェノール樹脂、変性フェノール樹脂、マレイン樹脂、アルキド樹脂、エポキシ樹脂、アクリル樹脂、無水マレインとテレフタル酸と多価アルコールとの重縮合によって得られる不飽和ポリエステル、尿素樹脂、メラミン樹脂、尿素−メラミン樹脂、キシレン樹脂、トルエン樹脂、グアナミン樹脂、メラミン−グアナミン樹脂、アセトグアナミン樹脂、グリプタール樹脂、フラン樹脂、シリコーン樹脂、ポリイミド樹脂、ポリアミドイミド樹脂、ポリエーテルイミド樹脂及びポリウレタン樹脂を挙げることができる。
【０２４５】
中でもシリコーン樹脂は、コアとの密着性、スペント防止の観点から、好ましく用いられる。シリコーン樹脂は、単独で用いることもできるが、被覆層の強度を高め好ましい帯電に制御するために、カップリング剤と併用して用いることが好ましい。更に、前述のカップリング剤は、その一部が、樹脂をコートする前に、キャリアコア表面に処理される、いわゆるプライマー剤として用いられることが好ましく、その後の被覆層が、共有結合を伴った、より密着性の高い状態で形成することができる。
【０２４６】
カップリング剤としては、アミノシランを用いると良い。その結果、ポジ帯電性を持ったアミノ基をキャリア表面に導入でき、良好にトナーに負帯電特性を付与できる。更に、アミノ基の存在は、金属化合物に好ましく処理されている親油化処理剤と、シリコーン樹脂の両者を活性化させるため、シリコーン樹脂のキャリアコアとの密着性を更に高め、同時に樹脂の硬化を促進することで、より強固な被覆層を形成することができる。
【０２４７】
被覆層の被覆処理時は、３０〜８０℃の温度下において、減圧状態で被覆することが好ましい。
【０２４８】
また、最終工程において２３℃，６０％ＲＨのような通常環境下に少なくとも２４時間以上放置することによる調湿工程を行なうことが好ましい。
【０２４９】
【実施例】
本発明を以下に実施例を示すことでより具体的に説明するが、これは本発明になんら限定するものではない。以下の部は質量部を意味する。
【０２５０】
本例の画像形成装置は、転写方式電子写真プロセス利用、接触帯電方式、反転現像方式、クリーナレス、最大通紙サイズがＡ３サイズのレーザビームプリンタである。
【０２５１】
本実施例での感光ドラムは、負帯電性の有機光導電体（ＯＰＣ）で、外径５０ｍｍであり、中心支軸を中心に１２０ｍｍ／ｓｅｃのプロセススピード（周速度）をもって矢示の反時計方向に回転駆動される。
【０２５２】
本発明での現像構成は、図３に則して下記のとおりである。
【０２５３】
現像スリーブ４ｂは感光ドラム１との最近接距離（Ｓ−Ｄｇａｐと称する）を３５０μｍに保たせて感光ドラム１に近接させて対向配設してある。この感光ドラム１と現像スリーブ４ｂとの対向部が現像部ｃである。現像スリーブ４ｂは現像部ｃにおいて感光ドラム１の進行方向とは逆方向に回転駆動される。この現像スリーブ４ｂの外周面に該スリーブ内のマグネットローラ４ｃの磁力により現像容器４ａ内の二成分現像剤４ｅの一部が磁気ブラシ層として吸着保持され、該スリーブの回転に伴い回転搬送され、現像剤コーティングブレード４ｄにより所定の薄層に整層され、現像部ｃにおいて感光ドラム１の面に対して接触して感光ドラム面を適度に摺擦する。現像スリーブ４ｂには電源Ｓ２から所定の現像バイアスが印加される。本例において、現像スリーブ４ｂに対する現像バイアス電圧は直流電圧（Ｖｄｃ）と交流電圧（Ｖａｃ）とを重畳した振動電圧である。より具体的には、
直流電圧；−３５０Ｖ
交流電圧；１５００Ｖ
とを重畳した振動電圧である。
【０２５４】
本実施例ではこのトナー帯電量制御手段７は、適度の導電性を持ったブラシ形状部材であり、ブラシ部を感光ドラム１面に接触させて配設してあり、負極性の電圧が電源Ｓ４より印加されている。ｅはブラシ部と感光ドラム１面の接触部である。トナー帯電量制御手段７を通過する感光ドラム１上の転写残トナーはその帯電極性が正規極性である負極性に揃えられる。
【０２５５】
以下、帯電ローラの製造方法を説明する。
【０２５６】
（帯電ローラＮｏ．１の製造方法）
・スチレン−ブタジエンゴム（ＳＢＲ） １００部
・カーボンブラック ３０部
・酸化亜鉛 ４．５部
・脂肪酸 ２部
【０２５７】
以上の材料を６０℃に調節した密閉型ミキサーにて１０分間混練した後、ＳＢＲ１００部に対してナフテン系オイル２０部を加え、２０℃に冷却した密閉型ミキサーで２０分間混練し、原料コンパウンドを調製した。さらに原料ゴムのスチレン−ブタジエンゴム（ＳＢＲ）１００部に対し加硫剤として硫黄０．５部、加硫促進剤としてチアゾール系１部およびチウラム系１部を原料コンパウンドに加え、２０℃に冷却した２本ロール機にて１０分間混練した。このコンパウンドを用い、直径６ｍｍ、長さ３２０ｍｍのステンレス製導電性支持体２ａの周囲にローラ状に弾性層２ｂをトランスファー成型にて加硫成型した。
【０２５８】
尚、帯電ローラの表面粗さはこの時点のローラ表面を研磨処理することで行なった。
【０２５９】
研磨後の弾性層ローラの１０点平均表面粗さは、Ｒｚ＝１１．２μｍであった。
【０２６０】
また抵抗制御層２ｃの材料として
・エピクロルヒドリンゴム １００部
・酸化チタン ３０部
をトルエンの溶媒にて分散溶解して抵抗制御層用塗料を作製した。この塗料を前記の弾性層２ｂ上にディッピング法にて塗布して膜厚７００μｍの抵抗制御層２ｃを形成した。
【０２６１】
さらに、形成した抵抗制御層２ｃ上に下記のようにして表面層２ｄを形成した。
【０２６２】
表面層２ｄの材料として
・ポリウレタン樹脂 １００部
・酸化チタン ９０部
をメチルエチルケトンの溶媒にて分散溶解して表面層用塗料を作製した。この塗料を抵抗制御層２ｃ上にディッピング法にて塗布して膜厚１０μｍの表面層２ｄを形成し、帯電ローラＮｏ．１を得た。１０点平均の表面粗さ（Ｒｚ）は１．４μｍであった。
【０２６３】
（帯電ローラＮｏ．２の製造方法）
帯電ローラＮｏ．１の研磨よりも粗い工程を用いて、研磨後の弾性層ローラの２ｂのＲｚを１５．０μｍとし、その他は帯電ローラＮｏ．１の製造方法と同様にして最終的には表面粗さ（Ｒｚ）５．１μｍの帯電ローラＮｏ．２を得た。
【０２６４】
（帯電ローラＮｏ．３の製造方法）
帯電ローラＮｏ．２の研磨よりも粗い工程を用いて、研磨後の弾性層ローラの２ｂのＲｚを２０．０μｍとし、その他は帯電ローラＮｏ．１の製造方法と同様にして最終的には表面粗さ（Ｒｚ）７．７μｍの帯電ローラＮｏ．３を得た。
【０２６５】
以下にキャリアの製造方法について説明する。
【０２６６】
（キャリアＮｏ．１の製造方法）
水媒体中にフェノール／ホルムアルデヒドモノマー（５０：５０）を混合分散した後、モノマー重量に対して、チタンカップリング剤で表面処理した０．２５μｍのマグネタイト粒子６１０部、０．６μｍのヘマタイト粒子３９０部を均一に分散させ、アンモニアを適宜添加しつつモノマーを重合させ、磁性粒子内包球状磁性樹脂キャリア芯材１（平均粒径３６μｍ，飽和磁化４０Ａｍ²／ｋｇ）を得た。
【０２６７】
一方、トルエン２０部，ブタノール２０部，水２０部，氷４０部を四つ口フラスコにとり、撹拌しながらＣＨ₃ＳｉＣｌ₃ １５モルと（ＣＨ₃）₂ＳｉＣｌ₂ １０モルとの混合物４０部を加え、更に３０分間撹拌した後、６０℃で１時間縮合反応を行った。その後シロキサンを水で十分に洗浄し、トルエン−メチルエチルケトン−ブタノール混合溶媒に溶解して固型分１０％のシリコーンワニスを調製した。
【０２６８】
このシリコーンワニスにシロキサン固型分１００部に対して２．０部のイオン交換水および２．０部の下記硬化剤（１）、１．０部の下記アミノシランカップリング剤（２）および、５．０部の下部シランカップリング剤（３）を同時添加し、キャリア被覆溶液Ｉを作製した。この溶液Ｉを塗布機（岡田精工社製：スピラコータ）により、前述のキャリア芯材１００部に、樹脂コート量が１部となるように塗布し、コートキャリアＮｏ．１を得た。
【０２６９】
このキャリアは５０％粒径が３６μｍであり、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が４．０体積％であり、ＳＦ−１の値は１１３であった。
【０２７０】
さらに比抵抗が、６×１０¹³Ωｃｍであり、飽和磁化が、４２Ａｍ²／ｋｇであった。
【０２７１】
【化４】

【０２７２】
【化５】

【０２７３】
【化６】

【０２７４】
（キャリアＮｏ．２の製造方法）
水媒体中にフェノール／ホルムアルデヒドモノマー（５０：５０）を混合分散した後、モノマー重量に対して、チタンカップリング剤で表面処理した０．２５μｍのマグネタイト粒子６４０部、０．６μｍのヘマタイト粒子２４０部を均一に分散させ、アンモニアを適宜添加しつつモノマーを重合させ、磁性粒子内包球状磁性樹脂キャリア芯材１（平均粒径３５μｍ，飽和磁化４９Ａｍ²／ｋｇ）を得た。これ以外は、キャリアＮｏ．１と同様な製造方法でキャリアＮｏ．２を製造した。
【０２７５】
得られたキャリアは、５０％粒径は３５μｍであり、５０％粒径の２／３以下の粒径（２Ｄ／３≧）の粒子の含有量が４．２体積％であり、ＳＦ−１の値は１１２であった。
【０２７６】
さらに比抵抗が８．８×１０¹¹Ωｃｍであり、飽和磁化が５１Ａｍ²／ｋｇであった。
【０２７７】
以下にトナーの製造方法について説明する。
【０２７８】
（トナーの製造例１）
反応容器中のイオン交換水１００００部に、０．１Ｍ−Ｎａ₃ＰＯ₄水溶液１００部ならびに１Ｍ−ＨＣｌ水溶液を８５部投入し、Ｎ₂パージしながら６５℃で６０分保温した。ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌しながら、１．０Ｍ−ＣａＣｌ₂水溶液６０部を一括投入し、ｐＨ＝６．５のリン酸カルシウム塩を含む水系媒体を調製した。
【０２７９】
一方、
・スチレン ８０部
・ｎ−ブチルアクリレート ２０部
・カーボンブラック １２部
・ジ−ｔｅｒｔ−ブチルサリチル酸金属化合物 １．０部
・縮合系化合物 １０部
（〔飽和ポリエステル（テレフタル酸−プロピレンオキサイド変性ビスフェノールＡ）
・エステルワックス（半値幅４℃、ＤＳＣピーク６５℃） １５部
・架橋剤（ジビニルベンゼン） ０．２５部
別容器中で上記材料を６５℃に保温し、ＴＫ方式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて均一に溶解、分解した。これに、重合開始剤２，２’−アゾビス（２，４−ジメチルバレロニトリル）３質量部を溶解し、重合性単量体組成物を調製した。
【０２８０】
反応容器中の前記水系媒体中に上記重合性単量体組成物を投入し、６５℃，Ｎ₂パージ下において、ＴＫ式ホモミキサーにて１２０００ｒｐｍで１０分間撹拌し、重合性単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ６５℃で６時間重合反応させ、さらに８５℃に昇温し、９時間反応させた後、８５℃で蒸留を行った。
【０２８１】
重合反応終了後、反応容器を冷却し、塩酸を加えリン酸カルシウム塩を溶解させた後、ろ過、水洗、乾燥をして、ブラックトナー母体（Ｂｋ１）を得た。
【０２８２】
該トナー（Ｂｋ１）の円相当個数平均径は６．３μｍ、フロー式粒子像分析装置による平均円形度は０．９７３、円形度の標準偏差は０．０３３であった。詳細は表１に示す。
【０２８３】
（トナーの製造例２〜４及び７〜１４）
着色剤、ワックス成分の種類と添加量を変更する以外は、前記トナーの製造例１と同様にして重合体粒子ブラックトナー母体（顔料カーボンブラック）Ｂｋ４〜Ｂｋ５、イエロートナー母体（顔料Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ９３）Ｙ１〜Ｙ３、マゼンタトナー母体（顔料キナクリドン）Ｍ１〜Ｍ３、シアントナー母体（顔料銅フタロシアニン）Ｃ１〜Ｃ３を得た。詳細は表１に示す。
【０２８４】
（トナーの製造例５）
・プロポキシ化ビスフェノールとフマル酸及びトリメリット酸を縮合して得られたポリエステル樹脂 １００部
・カーボンブラック ８部
・ジ−アルキルサリチル酸のジルコニウム錯化合物 ４部
・低分子量ポリプロピレン ４部
上記原料をヘンシェルミキサーにより、予備混合を行い、二軸押出し式混練機により溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度に粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。更に得られた微粉砕物を分級した後、機械的衝撃により球状化処理をし、重量平均粒径７．３μｍのブラックトナー母体（Ｂｋ２）を得た。
【０２８５】
該ブラックトナー母体Ｂｋ２の円相当個数平均径は６．５μｍ、フロー式粒子像分析装置による平均円形度は０．９６２、円形度の標準偏差は０．０３０であった。詳細は表１に示す。
【０２８６】
（トナーの製造例６）
ワックス成分の種類と添加量を変更する以外は、前記トナーの製造例５と同様にしてブラックトナー母体（Ｂｋ３）を得た。
【０２８７】
該ブラックトナー母体Ｂｋ３の円相当個数平均径は６．５μｍ、フロー式粒子像分析装置による平均円形度は０．９４５、円形度の標準偏差は０．０３７であった。詳細は表１に示す。
【０２８８】
（比較用トナーの製造例１〜４）
着色剤及びワックス成分の種類と添加量を変更する以外は、前記トナーの製造例１と同様にして重合体粒子（Ｂｋ６〜Ｂｋ７）、（Ｙ４）、（Ｍ４）、（Ｃ４）を得た。詳細は表１に示す。
【０２８９】
[実施例１]
トナーの製造例１で得られたブラックトナー粒子（Ｂｋ１）１００部と、平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）において、回転数３０００ｒｐｍ、撹拌時間１分間の条件下で混合し、その後平均粒径が０．３μｍであるチタニア微粒子１．０部を追加添加し、回転数３０００ｒｐｍにおいてさらに３分間撹拌し、負摩擦帯電性のブラックトナーを得た。
【０２９０】
このとき、トナー母体のＣ原子に対するＳｉ原子の遊離率は１．４％、Ｔｉ原子の遊離率は１２．３％であった。
【０２９１】
このブラックトナー７部に対し、キャリアＮｏ．１を９３部混合して現像剤を調製し、製造例１の帯電ローラを備えた図３に示す構成のＡ３サイズのレーザビームプリンタを用いて、画像面積比率５％の画像５００００枚の連続耐久試験を行った。１０枚目と５００００枚目に高温高湿環境下（３０℃／８０％）においてはベタ白画像とベタ黒画像をサンプルとして出力し、低温低湿環境下（１０℃／１５％）においてはハーフトーン画像を出力し、それぞれカブリと濃度安定性及び画像均一性と帯電ローラの汚染具合を評価した。
【０２９２】
得られた出力画像は、高温高湿環境（３０℃／８０％）においてはカブリ、画像濃度安定性共に極めて良好な結果が得られた。低温低湿環境（１０℃／１５％）においても、ハーフトーン画像均一性が斑無く、きめ細やかであり、また、帯電ローラを目視観察したところ汚染は確認されなかった。
【０２９３】
[実施例２]
トナーの製造例２で得られたイエロートナー粒子（Ｙ１）１００部と、平均粒径０．２５μｍの疎水性シリカ粒子を０．７部及び平均粒径０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂにおいて、回転数３０００ｒｐｍ、撹拌時間４分間の条件下で混合し、負帯電性のイエロートナーを得た。
【０２９４】
このとき、トナー母体のＣ原子に対するＳｉ原子の遊離率は６．３％、Ｔｉ原子の遊離率は１２．９％であった。
【０２９５】
このイエロートナーを用いて、以下実施例１と同様に評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０２９６】
[実施例３]
トナーの製造例３で得られたマゼンタトナー粒子（Ｍ１）１００部と、平均粒径０．０１μｍの疎水性シリカ０．７部をヘンシェルミキサー１０Ｂ（三井三池化工機社製）において、回転数３０００ｒｐｍ、撹拌時間２分間の条件下で混合し、その後平均粒径が０．０５μｍであるチタニア微粒子１．０部を追加添加し、回転数３０００ｒｐｍにおいてさらに２分間撹拌し、負摩擦帯電性のマゼンタトナーを得た。
【０２９７】
このとき、トナー母体のＣ原子に対するＳｉ原子の遊離率は１．２％、Ｔｉ原子の遊離率は２２．２％であった。
【０２９８】
このマゼンタトナーを用いて、以下実施例１と同様に評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０２９９】
[実施例４、参考例１〜６]
実施例１において用いるトナー粒子、外添剤の種類と添加量、帯電ローラ、キャリアを表１に示す様に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３００】
[参考例７]
実施例１においてマゼンタトナー粒子（Ｍ２）１００部を用い、外添条件を以下に示す様に、平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数４０００ｒｐｍ、撹拌時間２分間の条件下で混合し、その後平均粒径が０．３μｍであるチタニア微粒子１．０部を追加添加し、回転数４０００ｒｐｍにおいてさらに２分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０１】
[参考例８]
実施例１においてマゼンタトナー粒子（Ｍ３）１００部を用い、外添条件を以下に示す様に、平均粒径が０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数４０００ｒｐｍ、撹拌時間２分間の条件下で混合し、その後平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を追加添加し、回転数４０００ｒｐｍにおいてさらに２分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０２】
[参考例９]
実施例１においてシアントナー粒子（Ｃ２）１００部を用い、外添条件を以下に示す様に、平均粒径が０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数３０００ｒｐｍ、撹拌時間１分間の条件下で混合し、その後平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を追加添加し、回転数２０００ｒｐｍにおいてさらに１分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０３】
[参考例１０]
実施例１においてシアントナー粒子（Ｃ３）１００部を用い、外添条件を以下に示す様に、平均粒径０．０５μｍの疎水性シリカ粒子を０．７部及び平均粒径０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂを用いて、回転数３０００ｒｐｍ、撹拌時間１分間の条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０４】
[比較例１]
実施例１においてブラックトナー粒子（Ｂｋ６）１００部を用い、外添条件を以下に示す様に、平均粒径が０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数２０００ｒｐｍ、撹拌時間１分間の条件下で混合し、その後平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を追加添加し、回転数２０００ｒｐｍにおいてさらに１分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０５】
[比較例２]
実施例１においてイエロートナー粒子（Ｙ１）１００部を用い、外添条件を以下に示す様に、平均粒径が０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数４０００ｒｐｍ、撹拌時間５分間の条件下で混合し、その後平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を追加添加し、回転数３０００ｒｐｍにおいてさらに３分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０６】
チャージアップが発生し、画像濃度の低下が見られた。
【０３０７】
[比較例３]
実施例１においてマゼンタトナー粒子（Ｍ４）１００部を用い、外添条件を以下に示す様に、平均粒径０．０５μｍの疎水性シリカ粒子を０．７部及び平均粒径０．３μｍであるチタニア微粒子１．０部を、ヘンシェルミキサー１０Ｂを用いて、回転数４０００ｒｐｍ、撹拌時間６分間の条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３０８】
チャージアップが発生し、画像濃度の低下が見られた。
【０３０９】
[比較例４]
実施例１においてシアントナー粒子（Ｃ４）１００部を用い、外添条件を以下に示す様に、平均粒径０．０５μｍの疎水化シリカ微粒子０．７部を、ヘンシェルミキサー１０Ｂ（三井三池化工機社製）を用いて、回転数４０００ｒｐｍ、撹拌時間５分間の条件下で混合し、その後平均粒径が０．３μｍであるチタニア微粒子１．０部を追加添加し、回転数２０００ｒｐｍにおいてさらに１分間撹拌する条件に変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３１０】
顕著なチャージアップが発生し、画像濃度の低下が見られた。
【０３１１】
[比較例５]
実施例１において、用いるトナー粒子と帯電ローラを表１に示すように変えた以外は同様の方法により評価した。トナーの物性値を表１に、評価結果を表２に示す。
【０３１２】
上記実施例及び比較例中に記載の評価項目の説明とその評価基準を以下に示す。
【０３１３】
＜画像カブリ＞
カブリの測定は、ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳ（東京電色社製）を用い測定した。ブラック／マゼンタトナー画像は、グリーンフィルターで、イエロートナー画像はブルーフィルターで、シアントナー画像はアンバーフィルターをそれぞれ使用し、標準紙とベタ白パターンのサンプルの反射率を測定して下記式により算出した。なお、初期カブリは１０枚時サンプルにて、耐久カブリは５００００枚時サンプルにて評価した。カブリ量１．５％以下は実質的にカブリの無い良好な画像であり、カブリ量が１．５％を超えるとカブリの目立った不鮮明な画像である。評価のランク分けは以下のようにおこなった。
【０３１４】
カブリ（反射率；％）＝（標準紙の反射率；％）−（サンプルの反射率；％）
◎： ０．４％未満
○： ０．４％以上０．８％未満
△： ０．８％を超え１．５％未満
×： １．５％を超える
【０３１５】
＜画像濃度＞
画像濃度安定性の評価は、ベタ黒パターンのサンプルの、紙先端から３ｃｍの部分の濃度を、中央、両端の３点測定し平均値を求める。濃度測定は、反射濃度計ＲＤ９１８（マクベス社製）でおこなった。評価のランク分けは、以下のようにおこなった。
・初期濃度
◎：１０枚目の濃度が１．４５以上
○：１０枚目の濃度が１．４０以上１．４５未満
△：１０枚目の濃度が１．３５以上１．４０未満
×：１０枚目の濃度が１．３５未満
・耐久濃度低下
◎：１０枚目の濃度と５００００枚目の濃度差が０．１未満
○：１０枚目の濃度と５００００枚目の濃度差が０．１以上０．２未満
△：１０枚目の濃度と５００００枚目の濃度差が０．２以上０．３未満
×：１０枚目の濃度と５００００枚目の濃度差が０．３以上
【０３１６】
＜ハーフトーン画像均一性＞
画像均一性の評価は、得られたハーフトーン画像と帯電ローラの表面観察から判断した。評価のランク分けは、目視により以下のようにおこなった。
◎：ハーフトーン画像の均一性は良好で、帯電ローラ表面もきれいなレベル
○：ハーフトーン画像の均一性は良好ではあるが、帯電ローラ表面には軽微な汚染物が見受けられるレベル
△：ハーフトーン画像の均一性はやや不良で、帯電ローラ表面の汚染物もはっきり認識できるレベル
×：ハーフトーン画像の均一性は不良で、帯電ローラ周期で濃度ムラが生じ、帯電ローラ−表面の汚染物が非常に目に付くレベル
【０３１７】
＜ドラム融着＞
ドラム融着の評価は、得られた５％ｄｕｔｙの耐久画像と感光体の表面観察から判断した。評価のランク分けは、目視により以下のようにおこなった。
◎：画像に融着起因の画像欠陥がなく、感光体表面もきれいなレベル
○：画像に融着起因の画像欠陥はないものの、感光体表面には軽微な融着物が見受けられるレベル
△：画像に融着起因の画像欠陥が５点未満存在し、感光体表面にも融着物がはっきり認識できるレベル
×：画像に融着起因の画像欠陥が５点以上存在し、感光体表面にも多数融着物が認識できるレベル
【０３１８】
【表１】

【０３１９】
【表２】

【０３２０】
【発明の効果】
上記構成の本発明によれば、高温高湿環境下において多数枚の連続プリントを行っても、カブリの少ない濃度の安定した画像が得られ、ドラム融着を発生させないトナー及び画像形成方法が得られた。さらに低温低湿環境下において多数枚の連続プリントを行っても、帯電ローラへの汚染の少ない、画像均一性の良好なトナー及び画像形成方法も得られた。
【図面の簡単な説明】
【図１】画像形成方法の概略図である。
【図２】画像形成方法の概略図である。
【図３】本発明に従う画像形成装置例の概略構成模型図である。
【図４】感光体の層構成模型図である。
【図５】感光体の層構成模型図である。
【図６】感光体の層構成模型図である。
【図７】感光体の層構成模型図である。
【符号の説明】
１ 感光体
２ 帯電手段
５ 転写手段
４ｂ 現像スリーブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer and an image forming method for forming and developing an electric latent image in an electrophotographic method or an electrostatic printing method, and in particular, a means for combining development of an electrostatic latent image and recovery of transfer residual toner. The present invention relates to an image forming method performed by
[0002]
[Prior art]
Conventionally, many methods are known as electrophotographic methods. In general, a photoconductive substance is used, and an electrostatic charge latent image is formed on the photoconductor by various means, and then the latent image is developed with toner to form a toner image. After the toner image is transferred to the transfer material, the toner image is fixed on the transfer material by heat, pressure, heat and pressure, etc. to obtain a copy or printed matter. Toner particles that are not transferred onto the transfer material but remain on the photoconductor are removed from the photoconductor by a cleaning process.
[0003]
Conventionally, means such as blade cleaning, fur brush cleaning, and roller cleaning have been used for the cleaning process of the photoreceptor. The means mechanically scrapes off the transfer residual toner on the photoconductor or stops it to collect the transfer residual toner in a waste toner container. Therefore, problems are likely to occur due to the members constituting such means being pressed against the surface of the photoreceptor. For example, the surface of the photoreceptor is worn by strongly pressing the cleaning member.
[0004]
Furthermore, since the cleaning device is provided, the entire apparatus is inevitably enlarged, which has become a bottleneck when aiming to make the apparatus compact.
[0005]
In recent years, from the viewpoint of ecology, a system that does not generate waste toner is awaited. For example, Japanese Patent Publication No. 5-69427 proposes an image forming apparatus that employs a technique called development / cleaning or cleaner-less. In the image forming apparatus, one image is formed per one rotation of the photoreceptor so that the influence of the transfer residual toner does not appear on the same image. In JP-A 64-20587, JP-A-2-259784, JP-A-4-50886, and JP-A-5-165378, a transfer residual toner is scattered on a photosensitive member by a scattering member, and is not patterned. In this way, even when the same surface of the photoconductor is used a plurality of times for one image, a method that makes it difficult to manifest on the image has been proposed.
[0006]
However, when using the above process, it is certainly a cleaner-less system. However, it is difficult to make the entire device compact by using a member for non-patterning residual toner or applying a voltage to the member. It is.
[0007]
For these reasons, there has been a demand for an image forming apparatus that also has a system that does not contain waste toner in terms of downsizing the apparatus in consideration of the demand for space saving in the office and effective use of toner.
[0008]
On the other hand, for the photoreceptor charging step, there is a charging method using corona discharge called so-called corotron or scorotron. In addition, a charging method that suppresses ozone generation as much as possible was developed by bringing a charging member such as a roller, a fur brush, or a blade into contact with the surface of the photoconductor, and forming a discharge in a narrow space near the contact portion. Yes.
[0009]
However, in the charging method using corona discharge, a large amount of ozone is generated when corona discharge, particularly negative or positive corona is generated. Therefore, it is necessary to provide an electrophotographic apparatus with a filter for capturing ozone. In addition, there are problems such as an increase in the size of the apparatus or an increase in running cost.
[0010]
Therefore, a charging method that suppresses ozone generation as much as possible by forming a discharge in a narrow space has been developed. However, in the charging method by contacting the photosensitive member such as a blade or roller charging method, Problems such as toner fusing and charging roller contamination tend to occur. In particular, when these contact charging systems are introduced into a cleaner-less system, more severe conditions have arisen with respect to the fuser of the photosensitive member and the contamination of the charging roller due to the transfer residual toner, and further technical issues have to be cleared.
[0011]
[Problems to be solved by the invention]
As mentioned above, when designing copiers and printers based on the concept of ecology, the introduction of a cleanerless system and contact charging system is the preferred configuration. Even in these configurations, high-quality images can be maintained over a long period of time. An image forming method that can be used has been desired. That is, there has been a demand for an image forming method that can withstand long-term use by suppressing contamination of the charging roller and the photosensitive member as much as possible, and that is free from fogging and has a stable image density.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to provide a developer and an image forming method capable of obtaining an image with less fog and stable density even when a large number of sheets are continuously printed in a high temperature and high humidity environment in a cleanerless image forming method. There is.
[0013]
Another object of the present invention is to provide a developer and an image forming method in which, in a cleanerless image forming method, even when a large number of sheets are continuously printed in a high-temperature and high-humidity environment, the photosensitive member is less contaminated and does not cause drum fusion. It is to provide a method.
[0014]
Another object of the present invention is to provide a developer and an image forming method having a good image uniformity with little contamination to the charging roller even when a large number of continuous printing is performed in a low temperature and low humidity environment in a cleanerless image forming method. Is to provide.
[0015]
[Means for Solving the Problems]
  The present invention relates to a photosensitive member, a charging unit that charges the surface of the photosensitive member, an information writing unit that forms an electrostatic latent image on the charged photosensitive member, and a developer toner supplied to the electrostatic latent image. An image having developing means for visualizing the latent image and transfer means for transferring the visualized toner image to a transfer material, and collecting the toner remaining on the photosensitive member after the transfer process also for development of the electrostatic latent image A developer used in the forming method,
  The charging means for charging the surface of the photoreceptor is a charging roller having a conductive elastic layer, and the number of circles corresponding to the number of circles on the basis of the number-based circle-equivalent diameter measured by a flow type particle image measuring device-circularity scattergram. Diameter D₁The charging roller has a 10-point average surface roughness (Rz) smaller than (μm),
  The developer is a two-component developer composed of toner and carrier,The toner contains, as an external additive, 0.05 to 2.5 parts by mass of silica fine particles and 0.05 to 2.5 parts by mass of titania fine particles with respect to 100 parts by mass of the toner base.Against C atoms derived from the toner baseDerived from the silica fine particlesThe liberation rate of Si atoms is1.2Thru6.3%, AndDerived from the titania fine particlesTi atom liberation rate12.3Thru22.2%And
  The average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow type particle image measuring apparatus is 0.970 to 0.995, and the circularity standard deviation is 0.015 to 0.00. Less than 035It is related with the developing agent characterized by being.
[0016]
  The present invention also provides a photosensitive member, a charging unit that charges the surface of the photosensitive member, an information writing unit that forms an electrostatic latent image on the charged photosensitive member, and a developer toner to the electrostatic latent image. It has a developing means for visualizing the electrostatic latent image and a transfer means for transferring the visualized toner image to a transfer material, and collects residual toner on the photoconductor after the transfer process, together with the development of the electrostatic latent image. In the image forming method to
  The developer is a two-component developer composed of toner and carrier,The toner contains, as an external additive, 0.05 to 2.5 parts by mass of silica fine particles and 0.05 to 2.5 parts by mass of titania fine particles with respect to 100 parts by mass of the toner base.Against C atoms derived from the toner baseDerived from the silica fine particlesThe liberation rate of Si atoms is1.2Thru6.3%, AndDerived from the titania fine particlesTi atom liberation rate12.3Thru22.2%And
  The average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow type particle image measuring apparatus is 0.970 to 0.995, and the circularity standard deviation is 0.015 to 0.00. Less than 035It is characterized by
  The charging means for charging the surface of the photoreceptor is a charging roller having a conductive elastic layer, and the number of circles corresponding to the number of circles on the basis of the number-based circle-equivalent diameter measured by a flow type particle image measuring device-circularity scattergram. Diameter D₁The present invention relates to an image forming method for developing and collecting, wherein the 10-point average surface roughness (Rz) of the charging roller is smaller than (μm).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The principle of the cleanerless image forming method using the developing and cleaning method will be described. The principle is to control the charge polarity and charge amount of the toner on the photoreceptor in each electrophotographic process and to use a reversal development method.
[0018]
When a negatively chargeable photosensitive member and a negatively chargeable toner are used, an image visualized by a positive polarity transfer member is transferred to a transfer material in the transfer step. Depending on the relationship between the type of transfer material (difference in thickness, resistance, dielectric constant, etc.) and the image area, the charge polarity of the transfer residual toner varies from plus to minus. However, due to the negative polarity charging member for charging the negatively chargeable photoconductor, even if the transfer residual toner as well as the surface of the photoconductor becomes positive polarity in the transfer process, the charge polarity is uniformly negatively charged. Can be aligned. Therefore, when reversal development is used as the developing method, the transfer residual toner remains negatively charged on the light potential portion to be developed, and the dark portion potential that should not be developed is related to the development electric field. Transfer residual toner is attracted toward the upper toner carrier, and no toner remains on the dark potential portion.
[0019]
A more specific description will be given with reference to FIG.
[0020]
A toner charged on a toner carrying member (developing roller) 51 and a toner charged with a negative polarity by a developer having a carrier is used to reversely develop the electrostatic charge latent image on the negatively chargeable photoconductor 52 by reversal development. Get a statue. The toner image on the photoconductor is transferred to a transfer material 54 by a corona transfer charger 53 to which a plus bias is applied. Toner that cannot be transferred onto the transfer material remains on the photoreceptor 52 as residual transfer toner.
[0021]
This untransferred toner includes toner particles that have a positive polarity due to a positive-polarity transfer bias. When the transfer residual toner charges the surface of the photoreceptor 52 to the negative polarity by the corona charger 55, the toner particles having the positive polarity are converted to the negative polarity.
[0022]
Therefore, the toner on the photoconductor 52 that has passed through the corona charger 55 is uniformly negative, and the photoconductor surface potential is also negative.
[0023]
Next, an electrostatic charge latent image is formed by image exposure 56, and the electrostatic charge latent image on the photoreceptor 52 is developed by a developing roller 51 carrying toner. In reversal development, the image exposure part (bright part potential part) is developed, but the bias applied to the developing roller 52 is positioned between the photosensitive member non-exposure part and the exposure part potential, so that the non-exposure part (dark part potential) is developed. For the negative polarity toner existing on the upper part), an electrostatic force attracting the toner can be applied to collect the toner remaining after transfer.
[0024]
For the negative polarity toner present on the exposed portion, the force remaining on the surface of the photosensitive member acts, but this is a portion where a toner image is originally formed and does not cause a problem.
[0025]
FIG. 2 shows a one-component toner cartridge system using a charging roller 31 as means for charging the surface of the photoreceptor 36 to a negative polarity and a transfer roller 37 to which a positive bias is applied as transfer charging means.
[0026]
In any of the systems described above, it is possible to carry out a cleanerless image forming method by developing and cleaning by controlling the charging polarity of the transfer residual toner. However, if the charging means is a corona charger, Not only does the problem of suppression remain, but in continuous paper printing in harsh environments, the toner cannot be completely recovered yet, and further improvements have been desired.
[0027]
Further, in order to respond to the long life and high speed of machines that have been increasingly demanded in recent years, a two-component development system as shown in FIG. 3 is a more suitable system.
[0028]
Next, the two-component developer used in the present invention will be described.
[0029]
In dry two-component developers, fine toner particles are held on the surface of relatively large carrier particles by the electric force generated by friction between the two particles, and the toner particles are always in the desired image area on the photoconductor. It must have the correct chargeability and charge magnitude so that it can be attracted preferentially.
[0030]
In addition, the carrier must always be triboelectrically charged with a desired polarity and a sufficient charge amount of the toner particles during long-term use.
[0031]
However, if the paper is continuously passed over a long period of time, the toner deteriorates due to mechanical collision such as collision between developer particles due to multiple sheet copying or collision between developer particles and the developing mechanism, or heat generated by these actions, and the toner is charged. Performance is inferior. In addition, deteriorated toner, free external additives, and aggregates thereof are poor in developability and recoverability, so that the surface of the photoreceptor, the charging roller, and the carrier surface are contaminated. In particular, in the developing and collecting system, since there is no cleaner, it is necessary to suppress deterioration of the agent as much as possible.
[0032]
Photoconductor contamination and charging roller contamination disturb the latent image, resulting in fatal image defects such as a halftone image roughness.
[0033]
When the carrier is contaminated, image quality such as toner scattering or background fogging due to a decrease in charging characteristics and deterioration of density reproducibility is remarkably deteriorated. Therefore, if this carrier spent becomes severe, the entire developer must be replaced.
[0034]
For the purpose of preventing these image defects, it is known as an effective means to externally add inorganic fine particles such as silica to the toner in order to give the developer appropriate fluidity and tribo-applying property. However, if the adhesion of the external additive to the toner is weak, the free external additive causes contamination of the photoreceptor, the charging roller and the carrier. On the contrary, if the adhesion to the toner is increased, the external additive is strongly driven into the toner, the fluidity imparting effect of the external additive is diminished, and the tribo imparting property of the external additive is remarkably increased. The charge-up becomes severe.
[0035]
Thus, as a result of intensive studies by the present inventors, the present inventors have found an appropriate external additive free state that suppresses contamination of the charging roller and the photoreceptor as much as possible and does not cause carrier contamination and charge-up even in the developing and collecting system.
[0036]
That is, in a two-component image forming method using a toner to which fine particles containing silica atoms as main components and fine particles containing titanium atoms as main components are added, the liberation rate of Si atoms relative to C atoms derived from the toner base is The free state of 0.3 to 20% and the free rate of Ti atoms of 1.0 to 40% is the optimally matched free state in the system that combines the developing and collecting method and the charging roller. I found out.
[0037]
The reason is as follows.
[0038]
When Ti-based fine particles are added, the charge sharpening is generally known as the action. However, the present inventors have not only the effect of preventing excessive charging of the toner itself by the adhered Ti-based fine particles, but also the free Ti It was thought that the fine particles of the system also played a role in mitigating excessive tribo addition from the carrier. In addition, by setting each release rate within the above range, the developer transportability is maintained well even after printing a large number of sheets, and the triboelectric chargeability is stabilized.
[0039]
If the liberation rate of Si atoms is less than 0.3%, it is difficult to prevent charge-up even if Ti-based fine particles are added. As a cause, it is presumed that the toner charging effect due to the rubbing of the carrier particles and the stirring member becomes excessive if there is no free silica of a certain ratio or more with respect to the silica-based fine particles adhering to the toner surface.
[0040]
Further, the Ti atom liberation rate is required to be 1.0% or more. It is recognized that if it is less than 1.0%, the effect of mitigating tribo is weakened and the effect of preventing charge-up is not exhibited.
[0041]
Further, when the liberation rate of Si atoms exceeds 20% or the liberation rate of Ti atoms exceeds 40%, not only the sleeve and carrier are contaminated in a large number of prints but also development of free external additives. Contamination of the photoconductor and the charging roller due to the toner occurs, and the image quality is significantly deteriorated.
[0042]
As a more preferable range, the liberation rate of Si atoms is 0.3 to 12%, and the durability and the latitude of environmental fluctuation are widened and desirable.
[0043]
Further, in this system, the toner equivalent number average diameter D₁By making the average surface roughness of the charging roller as in the present invention smaller than (μm), the toner-derived substance damaged by the continuous paper-passing printing is greatly suppressed from entering and accumulating in the concave portion of the charging roller, and charging Significantly reduces roller contamination. This also suppresses the contamination of the photosensitive member when the number of printed sheets is increased, further enhances the above-described effects, and in the developing and collecting system, the fog suppression is good, there is no fusion, and the uniformity is good. We believe that the images are available.
[0044]
The 10-point average surface roughness (Rz, JIS-B0601) of the surface of the charging roller of the present invention is preferably 6 μm or less. Preferably it is 5 micrometers or less. More preferably, it is 3 μm or less. If the above range is exceeded, the amount of discharge increases and the photosensitive member, which is the object to be charged, is eroded, so that the so-called photosensitive member scraping is promoted and the life of the photosensitive member may be shortened.
[0045]
As a result of further detailed studies by the present inventors, in order to further stabilize the toner charge amount, the relationship between the Si atom liberation rate (Sif) and the Ti atom liberation rate (Tif) with respect to C atoms derived from the toner base material is known. It was found that the relationship of Tif ≧ Sif is preferable. Although the detailed mechanism is unknown, satisfying such a relationship not only prevents charge-up but also has an effect of suppressing fluctuations in toner tribo due to durability.
[0046]
As external additives, silica fine particles are contained in an amount of 0.05 to 2.5 parts by mass with respect to 100 parts by mass of the toner base, and titania fine particles are contained in an amount of 0.05 to 2.5 parts by mass with respect to 100 parts by mass of the toner base. Preferably it is. If it is less than 0.05 parts by mass, the effect as an external additive is reduced. If it exceeds 2.5 parts by mass, the transportability of the sleeve may deteriorate.
[0047]
More preferably, the average particle size of the external additive is 0.005 to 0.8 μm. The average particle size referred to here is a value obtained by measuring about 50 to 200 major axes of the external additive in an enlarged photograph taken with an electron microscope and calculating the average value thereof. In the case of an external additive in which a plurality of primary particles are aggregated, the aggregated particles are regarded as one particle, and the major axis is defined as the particle size of the particle. It is preferable to observe the external additives to be used individually and calculate the average particle diameter, but it is also possible to measure from the surface of the toner particles after external addition. In that case, the measured particle size is shown as a number frequency distribution (for example, at intervals of 0.005 μm), and the peak is taken as the average particle size. When there are a plurality of peaks, each peak is regarded as an average particle diameter.
[0048]
In order to make the liberation rate of Si atom and Ti atom into an appropriate range, a known external addition method can be used. A suitable stirring method for producing the toner of the present invention is not particularly limited as long as it is mechanically attached to the outside and can be carried out using a known stirring device. Preferably, a Henschel mixer, a homogenizer, or the like is used, and more preferably, a Henschel mixer can be used.
[0049]
The method for measuring the liberation rate of Si atoms and Ti atoms with respect to carbon atoms of the toner base is described in the annual meeting of the Electrophotographic Society (total 95 times), “Japan Hardcopy '97”, “New External Evaluation Method—Particle Analyzer”. Analysis of Toner by Toshiyuki Suzuki, Toshio Takahara, sponsored by the Electrophotographic Society, July 9-11, 1997, can be used. In this toner analysis method, toner particles are excited by introducing the toner particles into plasma, and an emission spectrum accompanying the excitation is detected to perform analysis. According to this analysis method, it is possible to simultaneously detect an emission spectrum accompanying excitation of a plurality of elements, and it is also possible to measure the periodicity of the emission spectrum.
[0050]
Synchronicity was used as a method for determining the liberation rate of the external additive. Elements contained in the same particle generate an excitation emission spectrum (synchronous spectrum) in the same period, while elements existing alone such as external additive free substance are not synchronized with the toner base alone. An excitation emission spectrum (asynchronous spectrum) is generated. By quantitatively determining the asynchronous / synchronous of the excitation emission spectrum derived from each of these elements, the liberation rate of the specific element with respect to the toner base was determined.
[0051]
In this application, based on the synchronization difference between the emission spectrum associated with the excitation of carbon atoms derived from the mother particles and the emission spectrum associated with the excitation of Si and Ti atoms derived from the external additive, unsynchronized atoms are liberated. It was regarded as an external additive, and the ratio was taken as the liberation rate of the external additive.
[0052]
As a specific measuring method, after measuring under the following conditions using PT1000 manufactured by Yokogawa Electric Corporation, the light emission synchronization of Si atoms and Ti atoms based on C atoms is applied to the following formula to release The rate was determined.
[0053]
<Measurement conditions of PT1000 manufactured by Yokogawa Electric Corporation>
-Number of detected C atoms in one measurement: 500-2500
・ Noise cut level: 1.5 or less
・ Sort time: 20 digits
・ Gas: O₂    0.1% He gas
・ Analysis wavelength:
C atom: 247.860 nm
Si atom: 288.160 nm
Ti atom: 334.900 nm
・ Channels used:
C atom: 3 or 4
Si atom: 1 or 2
Ti atom: 1 or 2
-Free rate of each atom
(Count number of atoms that did not emit light simultaneously with C atoms) / (Count number of atoms that emitted light simultaneously with C atoms + Count number of atoms that did not emit light simultaneously with C atoms) × 100 (%)
[0054]
The equivalent circle diameter, circularity, and frequency distribution of the toner in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring device FPIA is used. -1000 type (manufactured by Toa Medical Electronics Co., Ltd.) was used for measurement, and calculation was performed using the following formula.
[0055]
[Expression 1]

[0056]
Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.
[0057]
The circularity in the present invention is an index indicating the degree of unevenness of toner particles, and is 1.000 when the toner particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated.
[0058]
In the present invention, the circle-equivalent number average diameter D1 (μm) and the particle size standard deviation SDd, which mean the average value of the particle number frequency distribution based on the number of toners, are the particle size (central value) at the dividing point i of the particle size distribution. Is di, and the frequency is fi.
[0059]
[Expression 2]

[0060]

[0061]
[Equation 3]

[0062]
As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a dispersion means, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a 5φ titanium alloy chip as a vibrator is used, and subjected to a dispersion treatment for 5 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not become 40 degreeC or more.
[0063]
To measure the shape of the toner particles, the flow type particle image measuring device is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 / μl, and 1000 toner particles are obtained. Measure above. After the measurement, this data is used to obtain the equivalent circle diameter, circularity frequency distribution, etc. of the toner particles.
[0064]
The average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow type particle image measuring apparatus of the present invention is preferably 0.950 to 0.999. More preferable average circularity and circularity standard deviation are 0.950 to 0.999 and preferably less than 0.040, more preferably 0.950 to 0.995, and 0.015 or more and less than 0.035. It is preferably 0.970 to 0.995 and more preferably 0.015 to 0.035.
[0065]
When the average circularity is less than 0.950, the toner shape becomes considerably irregular, so that the toner transfer efficiency during continuous paper feeding deteriorates, and the transfer residual toner is placed on the photosensitive member. It becomes difficult to do.
When the average circularity exceeds 0.999, reproducibility and yield are remarkably deteriorated in production, leading to an increase in cost.
[0066]
When the circularity standard deviation exceeds 0.04, the toner shape distribution is widened, so that uniform transfer is deteriorated and development and recovery are difficult.
[0067]
Hereinafter, the image forming apparatus (image recording apparatus) of the embodiment will be described.
[0068]
FIG. 3 is a schematic configuration model diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process, a contact charging method, a reversal development method, cleanerless, and a maximum sheet passing size of A3 size.
[0069]
(1) Overall schematic configuration of printer
a) Photosensitive drum
Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum). As shown in the layer configuration model diagram of FIG. 4, the photosensitive drum 1 has an undercoat layer 1b that suppresses light interference and improves the adhesion of the upper layer on the surface of an aluminum cylinder (conductive drum base) 1a. The photocharge generation layer 1c and the charge transport layer 1d are coated in order from the bottom.
[0070]
The photosensitive drum of the present invention is not limited to the above. Next, a typical configuration of the electrophotographic photosensitive member will be described with reference to FIGS. 5, 6, and 7. FIG.
[0071]
The photosensitive layer is composed mainly of an organic photoconductor. As the organic photoconductor, an organic photoconductive polymer such as polyvinyl carbazole or a low molecular weight organic photoconductive substance is used in a binder resin. There are things contained in.
[0072]
In the electrophotographic photosensitive member of FIG. 5, a photosensitive layer 17 is provided on a conductive support 16, and this photosensitive layer 17 includes a charge generation layer 19 in which a charge generation material 18 is dispersedly contained in a binder resin, and charge transport. It is a laminated structure of the layer 20. In this case, the charge transport layer 20 is laminated on the charge generation layer 19.
[0073]
In the electrophotographic photoreceptor of FIG. 6, unlike the case of FIG. 5, the charge transport layer 20 is laminated below the charge generation layer 19. In this case, the charge generation layer 19 may contain a charge transport material.
[0074]
In the electrophotographic photosensitive member of FIG. 7, a photosensitive layer 17 is provided on a conductive support 16, and this photosensitive layer 17 contains a charge generation material 18 and a charge transport material (not shown) in a binder resin. Has been.
[0075]
Among these, as shown in FIG. 5, a photoreceptor having a structure in which the charge generation layer 19 and then the charge transport layer 20 are laminated in this order from the conductive support 16 side is preferable in the present invention.
[0076]
As the conductive support 16, a metal such as aluminum or stainless steel, a cylindrical cylinder such as paper or plastic, a sheet or a film is used. In addition, these cylindrical cylinders, sheets, or films may have a conductive polymer layer or a resin layer containing conductive particles such as tin oxide, titanium oxide, and silver particles as necessary.
[0077]
An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided between the conductive support 16 and the photosensitive layer 17.
[0078]
The undercoat layer is formed to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect against electrical breakdown of the photosensitive layer. Is done. The film thickness is about 0.2 to 2 μm.
[0079]
Examples of the charge generating substance include pyrylium, thiopioryl dye, phthalocyanine pigment, anthanthrone pigment, dibenzbilenequinone pigment, pyratron pigment, azo pigment, indigo pigment, quinacridone pigment, asymmetric quinocyanine, and quinocyanine.
[0080]
As the charge transport material, hydrazone compounds, pyrazoline compounds, styryl compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, polyarylalkane compounds, and the like can be used.
[0081]
In the charge generation layer 19, the charge generation material is well dispersed by a method such as a homogenizer, an ultrasonic wave, a ball mill, a vibration ball mill, a sand mill, an attritor and a roll mill together with a binder resin and a solvent in an amount of 0.5 to 4 Then, it is formed by coating and drying. The thickness is preferably 5 μm or less, particularly preferably in the range of 0.01 to 1 μm.
[0082]
The charge transport layer 20 is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform, and carbon tetrachloride. Is used. When this solution is applied, for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method or the like can be used, and drying is performed at a temperature in the range of 10 to 200 ° C., preferably 20 to 150 ° C. It can be carried out under air drying or static drying in minutes to 5 hours, preferably 10 minutes to 2 hours. The thickness of the generated charge transport layer is preferably 5 to 30 μm, particularly preferably 10 to 25 μm.
[0083]
Examples of the binder resin used to form the charge generation layer 19 and the charge transport layer 20 include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, and alkyd resin. And a resin selected from unsaturated resins and the like are preferable. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin or diallyl phthalate resin.
[0084]
In addition, the charge generation layer or the charge transport layer can contain various additives such as an antioxidant, an ultraviolet absorber, and a lubricant.
[0085]
b) Charging means
Reference numeral 2 denotes a contact charging device (contact charger) as charging means for uniformly charging the peripheral surface of the photosensitive drum 1, and this example is a charging roller (roller charger).
[0086]
The charging roller 2 holds both ends of the cored bar 2a rotatably by bearing members (not shown), and is urged toward the photosensitive drum by a pressing spring 2e so as to have a predetermined amount with respect to the surface of the photosensitive drum 1. It is brought into pressure contact with a pressing force, and rotates following the rotation of the photosensitive drum 1. A pressure contact portion between the photosensitive drum 1 and the charging roller 2 is a charging portion (charging nip portion) a.
[0087]
A charging bias voltage of a predetermined condition is applied from the power source S1 to the metal core 2a of the charging roller 2, whereby the peripheral surface of the rotating photosensitive drum 1 is contact-charged to a predetermined polarity and potential. In this example, the charging bias voltage for the charging roller 2 is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac).
[0088]
DC voltage: -500V
AC voltage; frequency f1000 Hz, peak-to-peak voltage Vpp 1300 V, and oscillating voltage superimposed with a sine wave. The peripheral surface of the photosensitive drum 1 is uniformly contact-charged to −500 V (dark potential Vd).
[0089]
The longitudinal length of the charging roller 2 is 320 mm, and the elastic layer 2b, the resistance control layer 2c, and the surface layer 2d are disposed below the cored bar (support member) 2a as shown in the layer configuration model diagram of FIG. It is a three-layer structure laminated sequentially. The elastic layer 2b is a foamed sponge layer for reducing charging noise, the resistance control layer 2c is a conductive layer for obtaining a uniform resistance as the whole charging roller, and the surface layer 2d is provided with a pinhole or the like on the photosensitive drum 1. This is a protective layer provided to prevent leakage even if there is a defect.
[0090]
Further details will be described.
[0091]
In FIG. 4, 2 is a charging member, 2a is a conductive support, 2b is an elastic layer, 2c is a resistance control layer, and 2d is a surface layer. The charging roller may be composed of an elastic layer 2b and a surface layer 2d without the resistance control layer 2c.
[0092]
For the conductive support 2a used in the present invention, metals such as iron, copper, stainless steel, aluminum and nickel can be used. Furthermore, these metal surfaces may be plated for the purpose of providing rust prevention and scratch resistance, but it is necessary not to impair the conductivity.
[0093]
In the charging roller 2, the elastic layer 2 b has appropriate elasticity to ensure good uniform adhesion of the charging roller 2 to the photoreceptor 1.
[0094]
The conductivity of the elastic layer 2b is adjusted by adding conductive particles such as carbon black or a conductive agent such as alkali metal salt and ammonium salt to an elastic material such as rubber. Elasticity is adjusted by the addition of process oil and plasticizer. Specific elastic materials for the elastic layer 2b include, for example, natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber. Examples include synthetic rubbers such as (BR), nitrile-butadiene rubber (NBR), and chloroprene rubber (CR), and resins such as polyamide resin, polyurethane resin, silicone resin, and fluororesin. Moreover, you may use the foam of the above-mentioned elastic material for the elastic layer 2b.
[0095]
The elastic layer has an electric resistance of 1 × 10^Three~ 1x10^TenIt preferably has conductivity in the range of [Ωcm]. Further, since the film thickness depends on the diameter of the conductive support, it is not particularly limited.
[0096]
The surface layer 2d is often provided in order to prevent bleed-out of the plasticizer or the like in the elastic layer 2b to the surface of the charging roller, or to maintain the slidability and smoothness of the surface of the charging roller. The surface layer 2d is provided by coating or coating a tube.
[0097]
When the surface layer 2d is provided by coating, specific materials include polyamide resins, polyurethane resins, acrylic resins, fluororesins, silicone resins, and the like, as well as epichlorohydrin rubber, urethane rubber, chloroprene rubber, acrylonitrile rubber, etc. Is mentioned. As a coating method, a dip coating method, a roll coating method, a spray coating method, or the like is preferable.
[0098]
When the surface layer 2d is provided by covering a tube, specific materials include nylon 12, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin), PVDF (polyvinylidene fluoride), FEP ( And a thermoplastic elastomer such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide.
[0099]
The tube may be a heat-shrinkable tube or a non-heat-shrinkable tube. In order to impart appropriate conductivity to the surface layer 2d, conductive particles such as carbon black and carbon graphite, conductive metal oxides such as conductive titanium oxide, conductive zinc oxide, and conductive tin oxide are used. A conductive agent is used.
[0100]
The electric resistance of the surface layer is 1 × 10⁶~ 1x10¹⁴The range is preferably [Ωcm].
[0101]
The film thickness is preferably 2 to 500 μm. More preferably, it is 2 to 250 μm.
[0102]
The resistance control layer 2c is often provided to control the resistance of the charging member. Specific materials for the resistance control layer 2c include resins such as polyamide resin, polyurethane resin, fluororesin, and silicone resin, as well as epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber. For the purpose of adjusting the resistance of the resistance control layer 2c, conductive particles such as carbon black and carbon graphite, conductive metal oxides such as conductive titanium oxide, conductive zinc oxide and conductive tin oxide, or alkali metal salts In addition, a conductive agent such as an ammonium salt can be dispersed.
[0103]
The resistance control layer 2c is also provided by coating or coating a tube.
[0104]
The electric resistance of the resistance control layer is 1 × 10⁶~ 1x10^TenThe range is preferably [Ωcm]. The film thickness is preferably 10 to 1000 μm. More preferably, it is 10 to 750 μm.
[0105]
The volume resistivity in the present invention is measured according to JIS K 6911.
[0106]
In FIG. 4, 2f is a charging roller cleaning member, which is a flexible cleaning film in this example. The cleaning film 2f is arranged in parallel to the longitudinal direction of the charging roller 2 and fixed at one end to a support member 2g that reciprocates a certain amount in the longitudinal direction. And is arranged to form a contact nip. The support member 2g is driven to reciprocate by a certain amount in the longitudinal direction via a gear train by a drive motor of the printer, and the charging roller surface layer 2d is rubbed with the cleaning film 2f. As a result, contaminants (fine powder toner, external additives, etc.) on the charging roller surface layer 2d are removed.
[0107]
c) Information writing means
Reference numeral 3 denotes exposure as information writing means for forming an electrostatic latent image on the surface of the charged photosensitive drum 1. There are a method using an LED array, a method using a semiconductor laser, a method using a liquid crystal shutter array, and the like.
[0108]
This example is a laser beam scanner using a semiconductor laser. A laser beam modulated in response to an image signal sent from a host device such as an image reading device to the printer side is output, and the uniformly charged surface of the rotating photosensitive drum 1 is scanned by a laser scanning exposure L (image) at an exposure position b. Exposure). Due to the laser scanning exposure L, the potential of the surface of the photosensitive drum 1 irradiated with the laser light is lowered, and electrostatic latent images corresponding to the scanned and exposed image information are sequentially formed on the surface of the rotating photosensitive drum 1. Go.
[0109]
d) Development means
Reference numeral 4 denotes a developing device (developer) as developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 to visualize the electrostatic latent image. This example is a two-component magnetic brush developing system. A reversal developing device.
[0110]
4a is a developing container, 4b is a non-magnetic developing sleeve, and this developing sleeve 4b is rotatably arranged in the developing container 4a with a part of its outer peripheral surface exposed to the outside. 4c is a non-rotating fixed magnet roller inserted in the developing sleeve 4b, 4d is a developer coating blade, 4e is a two-component developer contained in the developing container 4a, and 4f is disposed on the bottom side in the developing container 4a. The provided developer stirring member, 4g, is a toner hopper and contains replenishing toner.
[0111]
Thus, the toner in the developer coated as a thin layer on the surface of the rotating developing sleeve 4b and transported to the developing section c corresponds to the electrostatic latent image on the surface of the photosensitive drum 1 by the electric field due to the developing bias. By selectively adhering, the electrostatic latent image is developed as a toner image. In the case of this example, toner adheres to the exposed bright portion of the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed.
[0112]
The developer thin layer on the developing sleeve 4b that has passed through the developing portion c is returned to the developer reservoir in the developing container 4a with the subsequent rotation of the developing sleeve.
[0113]
In order to maintain the toner concentration of the two-component developer 4e in the developing container 4a within a predetermined substantially constant range, the toner concentration of the two-component developer 4e in the developing container 4a is adjusted by, for example, an optical toner concentration sensor (not shown). The toner hopper 4g is driven and controlled according to the detected information, and the toner in the toner hopper is supplied to the two-component developer 4e in the developing container 4a. The toner supplied to the two-component developer 4e is stirred by the stirring member 4f.
[0114]
e) Transfer means / fixing means
Reference numeral 5 denotes a transfer device, and this example is a transfer roller. The transfer roller 5 is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and the pressure nip portion is a transfer portion d. A transfer material (a member to be transferred, a recording material) P is fed to the transfer portion d from a paper feeding mechanism portion (not shown) at a predetermined control timing.
[0115]
The transfer material P fed to the transfer portion d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5, and during that time, the transfer roller 5 has a negative polarity which is a normal charging polarity of toner from the power source S 3. In this example, a positive transfer bias of +2 kV is applied in this example, so that the toner image on the surface of the photosensitive drum 1 is sequentially electrostatically transferred onto the surface of the transfer material P that is nipped and conveyed by the transfer portion d. It will be done.
[0116]
The transfer material P which has received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the rotary photosensitive drum 1 and is conveyed to the fixing device 6 (for example, a heat roller fixing device) to receive the toner image fixing process. Output as an image formed product (print, copy).
[0117]
(2) Cleanerless system and toner charge control
The printer of this example is cleanerless, and does not include a dedicated cleaning device that removes a small amount of transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image to the transfer material P. After the transfer, the untransferred toner on the surface of the photosensitive drum 1 is carried to the developing unit c through the charging unit a and the exposing unit b as the photosensitive drum 1 continues to rotate, and developed and cleaned (collected) by the developing device 3. (Cleanerless system).
[0118]
In this embodiment, as described above, the developing sleeve 4b of the developing device 4 is rotated in the developing portion c in a direction opposite to the traveling direction of the surface of the photosensitive drum 1, which is the transfer plate toner on the photosensitive drum 1. It is advantageous for recovery.
[0119]
Since the untransferred toner on the surface of the photosensitive drum 1 passes through the exposure portion b, the exposure process is performed from the untransferred toner.
[0120]
However, as described above, the transfer residual toner includes a mixture of normal polarity, reverse polarity (reversal toner), and low charge amount, among which reverse toner and toner with low charge amount. Adhering to the charging roller 2 when passing through the charging portion a causes the charging roller to be contaminated with toner more than allowable, resulting in a charging failure.
[0121]
Further, in order to effectively perform the development and cleaning of the transfer residual toner on the surface of the photosensitive drum 1 by the developing device 3, the charging polarity of the transfer residual toner on the photosensitive drum carried to the developing unit c is a normal polarity. In addition, the charge amount needs to be a charge amount of toner that can develop the electrostatic latent image on the photosensitive drum by the developing device. Reversal toner and toner with an inappropriate charge amount cannot be removed and collected from the photosensitive drum to the developing device, causing a defective image.
[0122]
Therefore, in the present embodiment, the charging polarity of the residual toner after transfer is aligned with the negative polarity that is the normal polarity at the position downstream of the transfer portion d in the photosensitive drum rotation direction and upstream of the charging portion a. Toner (developer) charge amount control means 7 is provided.
[0123]
By aligning the charge polarity of the transfer residual toner to the negative polarity that is the normal polarity, the photosensitive drum 1 is charged when the surface of the photosensitive drum 1 is charged from above the transfer residual toner in the charging unit a located further downstream. Therefore, the transfer residual toner is prevented from adhering to the charging roller 2.
[0124]
For this reason, the charge amount necessary for the untransferred toner needs to be 2.2 times or more as compared with the toner charge amount at the time of development.
[0125]
Next, the toner of the present invention will be described.
[0126]
First, the description about the external additive is described.
[0127]
As an external additive of the toner that can be used in the present invention, silica is preferably used as fine particles mainly containing Si atoms, and titania is preferably used as fine particles mainly containing Ti atoms. In addition to oxides such as zirconium oxide and magnesium oxide, silicon carbide, silicon nitride, boron nitride, aluminum nitride, magnesium carbonate, organosilicon compounds, and the like can be used in combination.
[0128]
In particular, silica is preferable in that the coalescence of the primary particles can be controlled arbitrarily to some extent depending on the starting material or oxidation conditions such as temperature. For example, such silica can be used as both a so-called dry process produced by vapor phase oxidation of silicon halides and alkoxides or dry silica called fumed silica, and so-called wet silica produced from alkoxides, water glass, etc. However, there are few silanol groups on the surface and inside the silica fine powder, and Na₂O, SO_Three ^2-Dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0129]
Furthermore, the silica is preferably hydrophobized in order to reduce the dependency of the toner charge amount on the environment, such as temperature and humidity, and to prevent excessive release from the toner surface. Examples of the hydrophobizing agent include coupling agents such as a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent. In particular, the silane coupling agent reacts with residual groups on the inorganic oxide fine particles or adsorbed water to achieve a uniform treatment, which is preferable in terms of stabilizing charging of the toner and imparting fluidity.
[0130]
The silane coupling agent has the following general formula
Rm SiYn
R: alkoxy group
m: an integer from 1 to 3
Y: alkyl group
Hydrocarbon groups including vinyl, glycidoxy and methacryl groups
n: an integer from 1 to 3
For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxy Examples thereof include silane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane and the like.
[0131]
More preferably, C_aH_{2a + 1}-Si (OC_bH_{2b + 1})_Three
a = 4-12, b = 1-3.
[0132]
Here, when a in the general formula is smaller than 4, the treatment becomes easy, but the hydrophobicity cannot be sufficiently achieved. On the other hand, if a is greater than 12, the hydrophobicity is sufficient, but the coalescence between the particles increases, and the fluidity imparting ability decreases.
[0133]
When b is larger than 3, the reactivity is lowered and the hydrophobicity is not sufficiently performed. Therefore, a in the above general formula is 4 to 12, preferably 4 to 8, and b is 1 to 3, preferably 1 to 2.
[0134]
The treatment amount is 1 to 50 parts by mass with respect to 100 parts by mass, preferably 3 to 40 parts by mass in order to uniformly treat the particles without coalescence, and the degree of hydrophobicity is 20 to 98%, preferably 30 to 30 parts. 90%, more preferably 40-80%.
[0135]
As the fine particles mainly containing Ti atoms, titania is preferable. The production method is not particularly limited, and a method of oxidizing a halide or alkoxide in a gas phase or a method of producing a product by hydrolysis in the presence of water can be used. For example, amorphous titanium oxide, anatase type titanium oxide, rutile type titanium oxide, or the like can be used.
[0136]
In the toner of the present invention, other additives such as a lubricant powder such as polyethylene fluoride powder, zinc stearate powder, polyvinylidene fluoride powder, cerium oxide powder, silicon carbide powder and the like within a range that does not substantially adversely affect the toner. An abrasive such as strontium titanate powder, an anti-caking agent such as aluminum oxide powder, or a conductivity imparting agent such as carbon black powder, zinc oxide powder or tin oxide powder, and organic and inorganic fine particles of reverse polarity. A small amount can be used as a developability improver.
[0137]
As the binder resin of the toner used when the toner of the present invention is produced by the pulverization method, polystyrene; a styrene-substituted homopolymer such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene Polymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene -Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile -Stins such as indene copolymers Emissions copolymer, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resins, polyester resins, polyamide resins, furan resins, epoxy resins, xylene resins.
[0138]
These resins are used alone or in combination.
[0139]
As the main component of the binder resin, a styrene copolymer, which is a copolymer of styrene and another vinyl monomer, is preferable in terms of developability and fixability.
[0140]
The comonomer for the styrene monomer of the styrene copolymer includes acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, doditer acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methacrylic acid. Monocarboxylic acid having a double bond such as methyl acid, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; maleic acid, butyl maleate, methyl maleate, maleate Dicarboxylic acids having a double bond such as dimethyl acid and its substitutes; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; Sulfonyl methyl ketone, vinyl ketones such as vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether. These vinyl monomers are used alone or in combination of two or more.
[0141]
The styrene copolymer is preferably crosslinked with a crosslinking agent such as divinylbenzene in order to widen the fixing temperature range of the toner and improve the offset resistance.
[0142]
As the polymerizable monomer used when the toner of the present invention is produced by the polymerization method, a vinyl polymerizable monomer capable of radical polymerization is used. As the vinyl polymerizable monomer, a monofunctional polymerizable monomer or a polyfunctional polymerizable monomer can be used.
[0143]
Monofunctional polymerizable monomers include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p -Styrene derivatives such as phenylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2 -Ethylhexyl acrylate acrylic polymerizable monomers such as n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate , N-nonyl methacrylate, diethyl phosphate ethyl methacrylate Methacrylic polymerizable monomers such as dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether Vinyl ether such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.
[0144]
As polyfunctional polymerizable monomers, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol Diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4- (acryloxydiethoxy) phenyl) propane, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4- (methacryloxy-diethoxy) phenyl) propane, Examples include 2,2′-bis (4- (methacryloxy / polyethoxy) phenyl) propane, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.
[0145]
In the present invention, the above monofunctional polymerizable monomers are used alone or in combination of two or more, or the above monofunctional polymerizable monomers and polyfunctional polymerizable monomers are used in combination. To do. The polyfunctional polymerizable monomer can also be used as a crosslinking agent.
[0146]
As the polymerization initiator used in the polymerization of the polymerizable monomer described above, an oil-soluble initiator and / or a water-soluble initiator is used. For example, as the oil-soluble initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) Azo compounds such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile; acetylcyclohexylsulfonyl peroxide, diisopropylperoxycarbonate, decanonyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide Oxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumylper Kisaido, t- butyl hydroperoxide, di -t- butyl peroxide, include peroxide initiators such as cumene hydroperoxide.
[0147]
Water-soluble initiators include ammonium persulfate, potassium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutyroamidine) hydrochloride, 2,2′-azobis (2-aminodinopropane) hydrochloric acid Salts, sodium azobis (isobutylamidine) hydrochloride, sodium 2,2′-azobisisobutyronitrile sulfonate, ferrous sulfate or hydrogen peroxide.
[0148]
In the present invention, in order to control the polymerization degree of the polymerizable monomer, a chain transfer agent, a polymerization inhibitor and the like can be further added and used.
[0149]
As the crosslinking agent used in the toner of the present invention, a compound having two or more polymerizable double bonds is used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These are used alone or as a mixture.
[0150]
Examples of the release agent used in the toner of the present invention include polymethylene wax such as paraffin wax, polyolefin wax, microcrystalline wax, and Fischer Tropish wax, amide wax, higher fatty acid, long chain alcohol, ketone wax, ester wax, and the like. Derivatives such as these graft compounds and block compounds may be mentioned, and distillation may be performed if necessary.
[0151]
Although represented by the following general structural formula, ester wax is particularly preferred.
[0152]
[Chemical 1]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R₁And R₂Represents an organic group having 1 to 40 carbon atoms, and R₁And R₂And n and m each represent an integer of 0 to 40, and n and m are not 0 at the same time. )
[0153]
[Chemical formula 2]

(In the formula, a and b represent an integer of 0 to 4, a + b is 4, and R₁Represents an organic group having 1 to 40 carbon atoms, n and m represent integers of 0 to 40, and n and m are not 0 simultaneously. )
[0154]
[Chemical Formula 3]

(Wherein, a and b represent an integer of 0 to 3, a + b is 3 or less, R₁And R₂Represents an organic group having 1 to 40 carbon atoms, and R₁And R₂And a group having a carbon number difference of 3 or more and R_ThreeRepresents an organic group having 1 or more carbon atoms, n and m represent integers of 0 to 40, and n and m are not 0 simultaneously. )
[0155]
The full width at half maximum of the toner is measured in accordance with ASTM D3418-82. And it is preferable that it is 10 degrees C or less, More preferably, 7 degrees C or less is good. When the temperature exceeds 10 ° C., the crystallinity is not high, and the hardness of the release agent is soft, which promotes contamination of the photoreceptor and the charging roller.
[0156]
The half-value width of the endothermic peak here is the temperature width of the endothermic chart that is half the height of the peak from the baseline in the endothermic peak.
[0157]
The endothermic peak value in the DSC endothermic curve of the release agent in the present invention is measured in accordance with ASTM D3418-82 after extracting the release agent from the toner by an arbitrary method.
[0158]
More preferably, a compound having a value of 50 to 100 ° C. is preferable, and in particular, a release agent having a DSC curve tangential separation temperature of 40 ° C. or more is more preferable.
[0159]
The measurement sample is accurately weighed within the range of 2 to 10 mg. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise temperature of 10 ° C./min at a temperature rise of 10 ° C./min.
[0160]
When the endothermic peak value is less than 50 ° C., the self-cohesive force of the release agent is weak, so it is difficult to form the inside or the center of the toner particle, and the release agent is deposited on the surface of the toner particle during the production of the toner particle. , The photosensitive member and the charging roller are easily contaminated.
[0161]
On the other hand, if the endothermic peak exceeds 120 ° C., the release agent does not easily permeate during fixing, and the fixing property at a low temperature and the fixing property of secondary colors (red, green, blue) having a large amount of toner development deteriorate. . Further, when toner particles are produced by a direct polymerization method, the solubility in the polymerizable monomer composition is reduced, and the toner particle size of the polymerizable monomer composition in the aqueous medium is reduced. The release agent is precipitated during the granulation of the droplets, making granulation difficult, which is not preferable.
[0162]
The molecular weight of the release agent is preferably that having a weight average molecular weight (Mw) of 300 to 1,500. If it is less than 300, the release agent is likely to be exposed on the surface of the toner particles, the developability is deteriorated, and fogging in a high temperature and high humidity environment is poor. In addition, contamination of the charging roller is significant. If it exceeds 1,500, the low-temperature fixability is lowered and the OHT transparency is also deteriorated. Particularly preferred are those in the range of 400 to 1,250.
[0163]
Further, when the ratio of weight average molecular weight / number average molecular weight (Mw / Mn) is 1.5 or less, the maximum peak of the DSC endothermic curve of the release agent becomes sharper, and the mechanical strength of the toner particles at room temperature is increased. In particular, excellent toner properties exhibiting sharp melting characteristics upon fixing can be obtained.
[0164]
The molecular weight of the release agent is measured by GPC under the following conditions.
[0165]
(GPC measurement conditions)
Apparatus: GPC-150C (manufactured by Waters)
Column: GMH-MT 30 cm 2 series (manufactured by Tosoh Corporation)
Temperature: 135 ° C
Solvent: o-dichlorobenzene (0.1% ionol added)
Flow rate: 1.0 ml / min
Sample: 0.4 ml of 0.15% sample was injected
[0166]
Measurement is performed under the above conditions, and a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample is used in calculating the molecular weight of the sample. Furthermore, it calculates by converting into polyethylene by the conversion formula derived | led-out from the Mark-Houwink viscosity formula.
[0167]
The penetration of the release agent is measured according to JIS K2235. The measurement temperature is 25 ° C. The penetration of the release agent is 15 degrees or less, more preferably 8 degrees or less. When the angle exceeds 15 degrees, contamination of the photosensitive member and the charging roller is promoted as in the case where the half-value width of the toner containing the release agent exceeds 10 ° C.
[0168]
The release agent is preferably used in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the binder resin when toner particles are produced by the melt-kneading pulverization method.
[0169]
In the case where toner particles are directly generated in an aqueous medium using the polymerizable monomer composition, 5 to 40 parts by mass (more preferably, 5 parts by mass with respect to 100 parts by mass of the polymerizable monomer). To 30 parts by mass), and as a result, 5 to 40 parts by mass (more preferably 5 to 30 parts by mass) of the release agent per 100 parts by mass of the binder resin produced from the polymerizable monomer is contained in the toner particles. It is good to be done.
[0170]
Compared with the dry toner manufacturing method, a large amount of the release agent is generally used in the toner manufacturing method using the polymerization method compared to the dry toner manufacturing method compared with the dry toner manufacturing method. This is particularly effective for the effect of preventing offset during fixing.
[0171]
As the colorant used in the toner of the present invention, a black colorant that is toned in black using carbon black, a magnetic material, and the following yellow / magenta / cyan colorant is used.
[0172]
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex methine compounds, and allylamide compounds are used as pigments. Specifically, C.I. I. Pigment Yellow 3.7.10.12.12.14.15.17.233.24.60.62.7.74.75.5.83.93.95.99.9.100.101.104.108.109.110 111.117.123.128.129.138.139.147.148.1500.166.168.169.177.179.180.181.18.181.185.191: 1.191.192.193.199 Etc. are preferably used. Examples of the dye system include C.I. I. solventYellow 33.56.79.82.93.112.162.163, C.I. I. disperse Yellow 42.64.2011.211 etc. are mentioned.
[0173]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254, C.I. I. Pigment Bio Red 19 is particularly preferable.
[0174]
As the cyan colorant, phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like are particularly preferably used.
[0175]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.
[0176]
The toner of the present invention may be used in combination with a charge control agent.
[0177]
The following substances are used for controlling the toner to be negatively charged.
[0178]
For example, organometallic compounds and chelate compounds are effective, and there are monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acids, and dicarboxylic acid-based metal compounds. Other examples include aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.
[0179]
Furthermore, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, resin charge control agents, and the like can be given.
[0180]
The following substances are used to control the toner to be positively charged.
[0181]
Modified products of nigrosine with nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs thereof Onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and their lake pigments (the rake agents include phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid Acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyls Borate, dioctyl tin borate, such as diorganotin tin borate such dicyclohexyl tin borate, resin charge control agent and the like. These can be used alone or in combination of two or more.
[0182]
The charge control agent is used in an amount of 0.01 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the binder resin.
[0183]
When the toner of the present invention is a polymerization toner, a condensation resin may be added.
[0184]
Examples of the condensation resin of the present invention include polyester, polycarbonate, phenol resin, epoxy resin, polyamide, and cellulose. More preferably, polyester is desired due to the variety of materials. 0.01 to 20 parts by mass, more preferably 0.5 to 10 parts by mass is used per 100 parts by mass of the binder resin.
[0185]
The additive for the purpose of improving various properties in the toner preferably has a particle size of 1/2 or less of the volume average diameter of the toner particles from the viewpoint of durability. The particle size of the additive means the average particle size obtained by observing the surface of the toner particles with an electron microscope. As additives for the purpose of imparting these characteristics, for example, the following are used.
[0186]
Examples of the fluidity-imparting agent include metal oxides (silicon oxide, aluminum oxide, titanium oxide, etc.) carbon black, carbon fluoride, and the like. Those subjected to hydrophobic treatment are more preferable.
[0187]
Abrasives include metal oxides (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitrides (silicon nitride, etc.), carbides (silicon carbide, etc.), metal salts (calcium sulfate, barium sulfate, etc.) , Calcium carbonate, etc.).
[0188]
Examples of the lubricant include fluorine-based resin powders (such as vinylidene fluoride and polytetrafluoroethylene) and fatty acid metal salts (such as zinc stearate and calcium stearate).
[0189]
Examples of the charge controllable particles include metal oxides (such as tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide) and carbon black.
[0190]
These additives are used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles.
[0191]
These additives may be used alone or in combination. Furthermore, you may hydrophobize (oil, coupling) as needed.
[0192]
The toner production method of the present invention will be described below.
[0193]
When the toner of the present invention is a pulverized toner, at least a binder resin and a colorant are kneaded and uniformly dispersed using a pressure kneader, an extruder, a media disperser, etc. A manufacturing method for producing toner particles by colliding with a target under a jet stream to finely pulverize the toner particles to a desired particle size, and further passing through a classification step to obtain a desired circularity using mechanical means, There are methods such as wet or dry thermal spheronization after pulverization.
[0194]
When the toner of the present invention is a polymerization method, it is not particularly limited, but is described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842. A direct toner production method using a suspension polymerization method; a soap-free polymerization method, which is soluble in monomers and directly polymerized in the presence of a water-soluble polymerization initiator to produce toner particles Examples thereof include production of toner particles by an emulsion polymerization method. In addition, production of an interfacial polymerization method such as a microcapsule production method, an in-situ polymerization method, a coacervation method, and the like can also be mentioned. Furthermore, as disclosed in JP-A-62-106473 and JP-A-63-186253, an interface association method for aggregating at least one kind of fine particles to obtain a desired particle size, etc. It is done.
[0195]
Particularly preferred is a suspension polymerization method in which small toner particles can be easily obtained. Furthermore, a seed polymerization method in which a monomer is further adsorbed to the obtained polymer particles and then polymerized using a polymerization initiator can be suitably used in the present invention. At this time, it is also possible to use a compound having polarity dispersed or dissolved in the monomer to be adsorbed.
[0196]
In the case of suspension polymerization, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition. Examples of the dispersant to be used include inorganic calcium oxide, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, Examples include calcium sulfate, barium sulfate, bentonite, silica, alumina, and sodium dodecyl sulfate. As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like are used. These dispersing agents or dispersing aids are preferably used in an amount of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer. In order to refine these dispersants, 0.001 to 0.1% by mass of a surfactant may be used in combination. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like are preferably used.
[0197]
Next, the carrier of the present invention will be described.
[0198]
The method for measuring the volume-based 50% particle size and particle size distribution of the carrier particles of the present invention is a laser diffraction particle size distribution measuring device (manufactured by SYNPATEC) equipped with a dry disperser (Rodos <RODOS>). Loss <HELOS>) and measured under conditions of a feed air pressure of 3 bar and a suction pressure of 0.1 bar.
[0199]
The carrier particle diameter is preferably 50% particle diameter (D) on a volume basis, preferably 15 to 60 μm, more preferably 25 to 50 μm. Furthermore, the content of particles having a particle size of 2/3 or less of the 50% particle size (2D / 3 ≧) is preferably 5% by volume or less, more preferably 0.1 to 5% by volume or less. Is good.
[0200]
When the 50% particle size of the carrier is less than 15 μm, carrier adhesion to the non-image area due to particles on the fine particle side of the particle size distribution of the carrier cannot be prevented well, which causes damage to the surface layer of the charging roller. As a result, the charging roller may be contaminated. If the 50% particle size of the carrier is larger than 60 μm, the ability to impart charge to the toner may be reduced and the development characteristics may be inferior.
[0201]
As the particle size distribution of the carrier of the present invention, when the content of particles having a particle size of 2/3 or less of 50% particle size exceeds 5% by volume, carrier adhesion due to carrier fine powder tends to occur. For this reason, the surface layer of the charging roller may be damaged, and as a result, the charging roller may be contaminated.
[0202]
In the present invention, the specific resistance of the carrier is 1 × 10⁸~ 1x10¹⁶Preferably, it is Ω · cm, more preferably 1 × 10⁹~ 1x10¹⁵It should be Ω · cm.
[0203]
Carrier specific resistance is 1 × 10⁸If it is less than Ω · cm, carrier adhesion to the surface of the photoconductor tends to occur, and the photoconductor is easily scratched or directly transferred onto paper, and image defects are likely to occur. Further, the developing bias may leak through the carrier and disturb the electrostatic latent image drawn on the photosensitive drum.
[0204]
Carrier specific resistance is 1 × 10¹⁶If it exceeds Ω · cm, a sharp edge-enhanced image is likely to be formed, and further, the charge on the carrier surface is less likely to leak, resulting in a decrease in image density due to a charge-up phenomenon, and charging to newly supplied toner. This may cause fogging and scattering due to the inability to do so. Further, the toner is charged with a substance such as an inner wall of the developing device, and the charge amount of the toner to be originally applied may become non-uniform. In addition, it tends to cause image defects such as electrostatic external additives.
[0205]
The specific resistance of the carrier was measured using a powder insulation resistance measuring instrument manufactured by Vacuum Riko Co., Ltd. The measurement conditions were as follows: a carrier left at 23 ° C. and 60% for 24 hours or more had a diameter of 20 mm (0.283 cm).²) In a measuring cell of 120 g / cm²Were measured with a load electrode of 500 V and a thickness of 2 mm.
[0206]
As for the magnetic properties of the carrier, the strength of magnetization at 1000 / 4π (kA / m) is preferably 20 to 100 (Am).²/ Kg), more preferably 30 to 65 (Am)²/ Kg) It is good that the magnetic force is low.
[0207]
Carrier magnetization is 100 (Am²/ Kg) is related to the carrier particle size, but the density of the magnetic brush formed on the developing sleeve at the developing pole decreases, the head length becomes longer, and it becomes rigid, so that it appears on the copy image. Sweep unevenness is likely to occur, and the durability of the toner is likely to deteriorate due to the copying or printing of a large number of sheets.
[0208]
Carrier magnetization is 20 (Am²/ Kg), even if the carrier fine powder is removed, the magnetic force of the carrier is lowered, carrier adhesion is likely to occur, and toner transportability is liable to be lowered.
[0209]
The measurement of the magnetic properties of the carrier was performed using an oscillating magnetic field type magnetic property automatic recording apparatus BHV-35 manufactured by Riken Denshi Co., Ltd. As measurement conditions, an external magnetic field of 1000 / 4π (kA / m) was created as the magnetic characteristics of the carrier powder, and the strength of magnetization at that time was determined. Make the carrier packed in a cylindrical plastic container so that the carrier particles do not move sufficiently, measure the magnetization moment in this state, measure the actual weight when the sample is put in , Magnetization strength (Am²/ Kg).
[0210]
In the present invention, examples of the metal compound particles used for the carrier core include magnetite or ferrite having magnetism represented by the following formula (1) or (2).
MO ・ Fe₂O_Three            ... (1)
M ・ Fe₂O_Four              ... (2)
(In the formula, M represents a trivalent, divalent or monovalent metal ion.)
[0211]
M includes Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Ba, Pb, and Li can be mentioned, and these can be used alone or in plural.
[0212]
Specific examples of the metal compound particles having magnetism include, for example, magnetite, Zn—Fe ferrite, Mn—Zn—Fe ferrite, Ni—Zn—Fe ferrite, Mn—Mg—Fe ferrite, Ca— Examples thereof include iron-based oxides such as Mn—Fe ferrite, Ca—Mg—Fe ferrite, Li—Fe ferrite, and Cu—Zn—Fe ferrite.
[0213]
Furthermore, in the present invention, the metal compound particles used for the carrier core may be a mixture of the above magnetic metal compound and the following nonmagnetic metal compound.
[0214]
Examples of nonmagnetic metal compounds include Al.₂O_Three, SiO₂, CaO, TiO₂, V₂O_Five, CrO, MnO₂, Α-Fe₂O_Three, CoO, NiO, CuO, ZnO, SrO, Y₂O_ThreeAnd ZrO₂Is mentioned. In this case, one kind of metal compound can be used, but it is particularly preferable to use a mixture of at least two kinds of metal compounds. In that case, it is more preferable to use particles having similar specific gravity and shape in order to increase the adhesion to the binder resin and the strength of the carrier core particles.
[0215]
Specific examples of combinations include, for example, magnetite and hematite, magnetite and r-Fe.₂O_Three, Magnetite and SiO₂, Magnetite and Al₂O_Three, Magnetite and TiO₂Magnetite and Ca—Mn—Fe based ferrite, and magnetite and Ca—MgFe based ferrite can be preferably used. Among these, a combination of magnetite and hematite can be particularly preferably used.
[0216]
When the above metal compound exhibiting magnetism is used alone or mixed with a nonmagnetic metal compound, the number average particle diameter of the metal compound exhibiting magnetism also varies depending on the number average particle diameter of the carrier core. However, it is preferably 0.02 to 2 μm, more preferably 0.05 to 1 μm.
[0217]
When the number average particle diameter of the metal compound exhibiting magnetism is less than 0.02 μm, it is difficult to obtain preferable magnetic characteristics. When the number average particle size of the metal compound exhibiting magnetism exceeds 2 μm, it is difficult to obtain a carrier having a preferable particle size with high strength due to non-uniform granulation.
[0218]
When a magnetic metal compound and a nonmagnetic compound are mixed and used, the number average particle diameter of the nonmagnetic metal compound is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm. good. In this case, the particle size ratio (rb / ra) between the number average particle size (average particle size ra) of the metal compound having magnetism and the number average particle size (average particle size rb) of the nonmagnetic metal compound is preferably Is preferably 1.0 to 5.0, more preferably 1.2 to 5.0.
[0219]
When the number average particle diameter of the non-magnetic metal compound is less than 0.05 μm, a preferable resistance cannot be obtained, and the carrier easily adheres. When the number average particle size of the non-magnetic metal compound exceeds 5 μm, it is difficult to obtain a carrier having a preferable particle size with high strength due to non-uniform granulation.
[0220]
Furthermore, when rb / ra is less than 1.0, the metal compound particles exhibiting ferromagnetism having a low specific resistance are likely to appear on the surface, and it is difficult to increase the specific resistance of the carrier core and the effect of preventing carrier adhesion is obtained. It becomes difficult. When rb / ra exceeds 5, the strength of the carrier tends to decrease, and carrier breakdown is likely to occur.
[0221]
The number average particle size of the metal oxide is 300 particles randomly having a particle size of 0.01 μm or more using a photographic image magnified 5000 to 20000 times by a transmission electron microscope H-800 manufactured by Hitachi, Ltd. One or more samples were extracted, measured with a horizontal ferret diameter as a metal oxide particle diameter by an image processing analyzer Luzex3 manufactured by Nireco Corporation, and averaged to calculate the number average particle diameter.
[0222]
The specific resistance of the metal compound dispersed in the binder resin is such that the specific resistance of the magnetic metal compound particles is 1 × 10.^ThreeThose having a range of Ω · cm or more are preferable. Particularly, when a metal compound having magnetism and a nonmagnetic compound are mixed and used, the specific resistance of the metal compound particles having magnetism is 1 × 10.^ThreeA range of Ω · cm or more is preferable, and the other nonmagnetic metal compound particles preferably have a higher specific resistance than the magnetic metal compound particles, and preferably the specific resistance of the nonmagnetic metal compound used in the present invention. Is 1 × 10⁸Ω · cm or more, more preferably 1 × 10^TenThe thing more than Ω · cm is good.
[0223]
Specific resistance of magnetic metal compound particles is 1 × 10^ThreeIf it is less than Ω · cm, it is difficult to obtain a desired high specific resistance even if the content is reduced, which leads to charge injection, which tends to cause image quality deterioration and carrier adhesion. Further, when a magnetic metal compound and a non-magnetic compound are used in combination, the specific resistance of the non-magnetic metal compound is 1 × 10.⁸If it is less than Ω · cm, the specific resistance of the magnetic carrier core is lowered, and the effect of the present invention is hardly obtained.
[0224]
In the present invention, the specific resistance measurement method for the magnetic metal compound and the nonmagnetic metal compound is performed according to the specific resistance measurement method for the carrier particles.
[0225]
In the carrier core of the present invention, the content of the metal compound is preferably 80 to 99% by mass with respect to the carrier core.
[0226]
When the content of the metal compound is less than 80% by mass, the chargeability tends to become unstable, and the carrier is charged particularly in a low-temperature and low-humidity environment. The agent easily adheres to the surface of the carrier particles, and an appropriate specific gravity cannot be obtained. When the content of the metal compound exceeds 99% by mass, the carrier strength is lowered, and problems such as carrier cracking due to durability tend to occur.
[0227]
Furthermore, as a preferable form of the present invention, in the carrier core containing a mixture of a magnetic metal compound and a nonmagnetic compound, the content of the metal compound having magnetism in the entire metal compound contained is preferably 50 to 95. It is good that it is mass%, More preferably, it is 55-95 mass%.
[0228]
When the content of the metal compound having magnetism in the entire metal compound contained is less than 50% by mass, the resistance of the core is improved, but the magnetic force as a carrier is reduced, which may lead to carrier adhesion. is there. If the content of the metal compound having magnetism in the entire metal compound contained exceeds 95% by mass, depending on the specific resistance of the metal compound having magnetism, it may not be possible to achieve higher core resistance.
[0229]
The binder resin for the carrier core particles used in the present invention is a thermosetting resin and is preferably a resin partially or wholly crosslinked three-dimensionally. As a result, the dispersed metal compound particles can be firmly bound, so that the strength of the carrier core can be increased, and the detachment of the metal compound does not easily occur even when a large number of copies are made.
[0230]
The method for obtaining the magnetic material-dispersed carrier core is not particularly limited to the method described below, but in the present invention, from a solution in which the monomer and the solvent are uniformly dispersed or dissolved, Production method of polymerization method in which particles are produced by polymerizing monomers, in particular, a magnetic substance with a sharp particle size distribution and a small amount of fine powder by applying a lipophilic treatment to the metal oxide dispersed in the carrier core particles A method of obtaining a dispersed resin carrier core is preferably used.
[0231]
In the present invention, in the case of a carrier used in combination with a small particle size toner having a weight average particle size of 1 to 10 μm in order to achieve high image quality, the carrier particle size is also reduced according to the particle size of the toner. The above-described manufacturing method is particularly preferable because a carrier with less fine powder can be manufactured regardless of the average particle diameter even if the carrier particle diameter is reduced.
[0232]
As the monomer used for the binder resin of the carrier core particle, a radical polymerizable monomer can be used. For example, styrene; styrene derivatives such as o-methyl styrene, m-methyl styrene, p-methoxy styrene, p-ethyl styrene, p-tertiary butyl styrene; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate Acrylates such as n-propyl acrylate, isobutyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methacrylic acid, methyl methacrylate , Ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, meta Methacrylic acid esters such as phenyl laurate, dimethylaminomethyl methacrylate, diethylaminoethyl methacrylate, benzyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide; methyl vinyl ether, ethyl vinyl ether , Propyl vinyl ether, n-butyl ether, isobutyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl ether, p-chlorophenyl ether, p-bromophenyl ether, p-nitrophenyl vinyl ether, p-methoxyphenyl vinyl ether And vinyl ethers; and diene compounds such as butadiene.
[0233]
These monomers can be used alone or in combination, and a suitable polymer composition can be selected so that preferable characteristics can be obtained.
[0234]
As described above, the binder resin of the carrier core particles is preferably three-dimensionally crosslinked. However, as a crosslinking agent for three-dimensionally crosslinking the binder resin, a polymerizable double bond is used. It is preferable to use a crosslinking agent having two or more per molecule. Examples of such cross-linking agents include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and 1,3-butylene glycol. Dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, penta Erythritol dimethacrylate, pentaerythritol tetramethacrylate, glycerol Alkoxy dimethacrylate, N, N-divinyl aniline, divinyl ether, and a divinyl sulfide and divinyl sulfone. These may be used by mixing two or more kinds as appropriate. The cross-linking agent can be mixed in advance with the polymerizable mixture, or can be appropriately added during the polymerization as necessary.
[0235]
Other binder resin monomers for carrier core particles include bisphenols and epichlorohydrin as starting materials for epoxy resins; phenols and aldehydes of phenolic resins; urea and aldehydes of urea resins; melamine and aldehydes.
[0236]
The most preferred binder resin is a phenolic resin. Examples of the starting material include phenol compounds such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcil, and p-tert-butylphenol, and aldehyde compounds such as formalin, paraformaldehyde, and furfural. A combination of phenol and formalin is particularly preferable.
[0237]
When these phenol resins or melamine resins are used, a basic catalyst can be used as a curing catalyst. As the basic catalyst, various catalysts used in the production of ordinary resole resins can be used. Specific examples include amines such as aqueous ammonia, hexamethylenetetramine, diethyltriamine, and polyethyleneimine.
[0238]
In the present invention, the metal compound contained in the carrier core is preferably oleophilic in order to sharpen the particle size distribution of the magnetic carrier particles and to prevent the metal compound particles from being detached from the carrier. . When forming carrier core particles in which a metal compound subjected to lipophilic treatment is dispersed, particles insolubilized in the solution are generated at the same time as the polymerization reaction proceeds from a liquid in which the monomer and solvent are uniformly dispersed or dissolved. At that time, it is considered that the metal oxide is taken in uniformly and at a high density inside the particles and has an effect of preventing aggregation of the particles and sharpening the particle size distribution. Furthermore, when a metal compound subjected to oleophilic treatment is used, it is not necessary to use a suspension stabilizer such as calcium fluoride, charging stability is inhibited due to the suspension stabilizer remaining on the carrier surface, and during coating Inhomogeneity of the coating resin and reaction inhibition when a reactive resin such as a silicone resin is coated can be prevented.
[0239]
The oleophilic treatment is treated with an oleophilic agent which is an organic compound having one or more functional groups selected from epoxy groups, amino groups and mercapto groups, and a mixture thereof. Is preferred.
[0240]
The magnetic metal oxide particles are preferably treated with a lipophilic treatment agent in an amount of 0.1 to 10 parts by weight, more preferably 0.2 to 6 parts by weight per 100 parts by weight of the magnetic metal oxide particles. It is preferable for enhancing the lipophilicity and hydrophobicity of the metal oxide particles.
[0241]
Examples of the lipophilic agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane, epichlorohydrin, and glycidol. And styrene- (meth) acrylic acid glycidyl copolymer.
[0242]
Examples of the lipophilic agent having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxydiethoxysilane, γ-aminopropyltriethoxysilane, ethylenediamine, ethylenetriamine, and styrene- (meth) acryl. An acid dimethylaminoethyl copolymer and isopropyl tri (N-aminoethyl) titanate are used.
[0243]
Examples of the lipophilic agent having a mercapto group include mercaptoethanol, mercaptopropionic acid, and γ-mercaptopropyltrimethoxysilane.
[0244]
The resin that coats the surface of the carrier core is not particularly limited. Specifically, for example, acrylic resin such as polystyrene and styrene-acrylic copolymer, vinyl chloride, vinyl acetate, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, Polyvinyl pyrrolidone, petroleum resin, cellulose, cellulose derivative, novolak resin, low molecular weight polyethylene, saturated alkyl polyester resin, aromatic polyester resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyphenylene sulfide resin, poly Ether ketone resin, phenol resin, modified phenol resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, anhydrous male Unsaturated polyester, urea resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin , Furan resin, silicone resin, polyimide resin, polyamideimide resin, polyetherimide resin and polyurethane resin.
[0245]
Of these, silicone resins are preferably used from the viewpoint of adhesion to the core and prevention of spent. The silicone resin can be used alone, but is preferably used in combination with a coupling agent in order to increase the strength of the coating layer and control the charge to a preferable level. Furthermore, the coupling agent described above is preferably used as a so-called primer agent in which a part of the coupling agent is treated on the surface of the carrier core before coating the resin, and the subsequent coating layer is accompanied by a covalent bond. , It can be formed in a more adhesive state.
[0246]
Aminosilane is preferably used as the coupling agent. As a result, an amino group having positive chargeability can be introduced on the surface of the carrier, and negative charge characteristics can be imparted to the toner satisfactorily. Furthermore, the presence of amino groups activates both the lipophilic treatment agent that is preferably treated with the metal compound and the silicone resin, thereby further improving the adhesion between the silicone resin carrier core and simultaneously curing the resin. By promoting the above, a stronger coating layer can be formed.
[0247]
During the coating treatment of the coating layer, it is preferable to coat in a reduced pressure state at a temperature of 30 to 80 ° C.
[0248]
In the final step, it is preferable to perform a humidity control step by leaving it in a normal environment such as 23 ° C. and 60% RH for at least 24 hours.
[0249]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the examples. The following parts mean parts by mass.
[0250]
The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process, a contact charging method, a reversal development method, cleanerless, and a maximum sheet passing size of A3 size.
[0251]
The photosensitive drum in this embodiment is a negatively charged organic photoconductor (OPC), has an outer diameter of 50 mm, and has a process speed (peripheral speed) of 120 mm / sec centered on the central support shaft. It is rotationally driven in the direction.
[0252]
The development configuration in the present invention is as follows in accordance with FIG.
[0253]
The developing sleeve 4b is disposed opposite to the photosensitive drum 1 so that the closest distance (referred to as S-Dgap) to the photosensitive drum 1 is maintained at 350 μm. A facing portion between the photosensitive drum 1 and the developing sleeve 4b is a developing portion c. The developing sleeve 4b is driven to rotate in the direction opposite to the traveling direction of the photosensitive drum 1 in the developing portion c. A part of the two-component developer 4e in the developing container 4a is adsorbed and held as a magnetic brush layer on the outer peripheral surface of the developing sleeve 4b by the magnetic force of the magnet roller 4c in the sleeve, and is rotated and conveyed as the sleeve rotates. A predetermined thin layer is formed by the developer coating blade 4d, and in contact with the surface of the photosensitive drum 1 at the developing portion c, the surface of the photosensitive drum is rubbed appropriately. A predetermined developing bias is applied to the developing sleeve 4b from the power source S2. In this example, the developing bias voltage for the developing sleeve 4b is an oscillating voltage obtained by superimposing a DC voltage (Vdc) and an AC voltage (Vac). More specifically,
DC voltage: -350V
AC voltage: 1500V
Is a vibration voltage obtained by superimposing and.
[0254]
In the present embodiment, the toner charge amount control means 7 is a brush-shaped member having moderate conductivity, and is disposed in contact with the surface of the photosensitive drum 1, and the negative voltage is applied to the power source S4. Is applied. e is a contact portion between the brush portion and the photosensitive drum 1 surface. The untransferred toner on the photosensitive drum 1 that passes through the toner charge amount control means 7 has a negative polarity in which the charge polarity is a normal polarity.
[0255]
Hereinafter, a method for manufacturing the charging roller will be described.
[0256]
(Method for manufacturing charging roller No. 1)
・ Styrene-butadiene rubber (SBR) 100 parts
・ Carbon black 30 parts
・ 4.5 parts of zinc oxide
・ Fatty acid 2 parts
[0257]
After kneading the above materials for 10 minutes with a closed mixer adjusted to 60 ° C, add 20 parts of naphthenic oil to 100 parts of SBR, knead for 20 minutes with a closed mixer cooled to 20 ° C, and mix the raw material compound. Prepared. Further, 100 parts of styrene-butadiene rubber (SBR) as raw material rubber was added with 0.5 parts of sulfur as a vulcanizing agent, 1 part of thiazole and 1 part of thiuram as vulcanization accelerators, and cooled to 20 ° C. It knead | mixed for 10 minutes with the 2 roll machine. Using this compound, the elastic layer 2b was vulcanized by transfer molding around a stainless steel conductive support 2a having a diameter of 6 mm and a length of 320 mm.
[0258]
The surface roughness of the charging roller was obtained by polishing the roller surface at this time.
[0259]
The 10-point average surface roughness of the elastic layer roller after polishing was Rz = 11.2 μm.
[0260]
As a material for the resistance control layer 2c
・ Epichlorohydrin rubber 100 parts
・ Titanium oxide 30 parts
Was dispersed and dissolved in a toluene solvent to prepare a resistance control layer coating material. This paint was applied on the elastic layer 2b by dipping to form a resistance control layer 2c having a thickness of 700 μm.
[0261]
Further, a surface layer 2d was formed on the formed resistance control layer 2c as follows.
[0262]
As a material for the surface layer 2d
・ 100 parts of polyurethane resin
・ Titanium oxide 90 parts
Was dispersed and dissolved in a solvent of methyl ethyl ketone to prepare a coating for the surface layer. This paint is applied onto the resistance control layer 2c by dipping to form a surface layer 2d having a thickness of 10 μm. 1 was obtained. The 10-point average surface roughness (Rz) was 1.4 μm.
[0263]
(Method for manufacturing charging roller No. 2)
Charging roller No. 1 is set to 15.0 μm, and the rest of the charging roller No. 1 is set to 15.0 μm. In the same manner as the manufacturing method of No. 1, the charging roller No. 1 having a surface roughness (Rz) of 5.1 μm is finally obtained. 2 was obtained.
[0264]
(Method for manufacturing charging roller No. 3)
Charging roller No. 2 is set to 20.0 μm, and the rest of the charging roller No. 2 is set to 20.0 μm. In the same manner as in the manufacturing method of No. 1, a charging roller No. 1 having a surface roughness (Rz) of 7.7 μm is finally obtained. 3 was obtained.
[0265]
A method for manufacturing the carrier will be described below.
[0266]
(Manufacturing method of carrier No. 1)
After mixing and dispersing a phenol / formaldehyde monomer (50:50) in an aqueous medium, 610 parts of 0.25 μm magnetite particles and 390 parts of 0.6 μm hematite particles surface-treated with a titanium coupling agent based on the monomer weight. Is uniformly dispersed, the monomer is polymerized while adding ammonia as appropriate, and the magnetic particle-containing spherical magnetic resin carrier core material 1 (average particle size 36 μm, saturation magnetization 40 Am)²/ Kg).
[0267]
Meanwhile, 20 parts of toluene, 20 parts of butanol, 20 parts of water, and 40 parts of ice are placed in a four-necked flask and stirred with CH._ThreeSiCl_Three  15 mol and (CH_Three)₂SiCl₂  After adding 40 parts of a mixture with 10 mol and further stirring for 30 minutes, a condensation reaction was carried out at 60 ° C. for 1 hour. Thereafter, the siloxane was thoroughly washed with water and dissolved in a toluene-methyl ethyl ketone-butanol mixed solvent to prepare a silicone varnish having a solid content of 10%.
[0268]
To this silicone varnish, 2.0 parts of ion exchange water and 2.0 parts of the following curing agent (1), 1.0 part of the following aminosilane coupling agent (2) 0.0 parts of the lower silane coupling agent (3) was simultaneously added to prepare a carrier coating solution I. This solution I was applied to 100 parts of the carrier core material with a coating machine (Okada Seiko Co., Ltd .: Spiracoater) so that the resin coating amount was 1 part. 1 was obtained.
[0269]
This carrier has a 50% particle size of 36 μm, a content of particles having a particle size of 2/3 or less of the 50% particle size (2D / 3 ≧) is 4.0% by volume, and the value of SF-1 is 113.
[0270]
Furthermore, the specific resistance is 6 × 10¹³Ωcm, saturation magnetization is 42 Am²/ Kg.
[0271]
[Formula 4]

[0272]
[Chemical formula 5]

[0273]
[Chemical 6]

[0274]
(Manufacturing method of carrier No. 2)
After mixing and dispersing the phenol / formaldehyde monomer (50:50) in an aqueous medium, 640 parts of 0.25 μm magnetite particles and 240 parts of 0.6 μm hematite particles surface-treated with a titanium coupling agent based on the monomer weight. Is uniformly dispersed, and the monomer is polymerized while appropriately adding ammonia, and the magnetic particle-containing spherical magnetic resin carrier core material 1 (average particle diameter 35 μm, saturation magnetization 49 Am)²/ Kg). Other than this, carrier no. Carrier No. 1 in the same manufacturing method as in No. 1. 2 was produced.
[0275]
The obtained carrier has a 50% particle size of 35 μm, a content of particles having a particle size of 2/3 or less of the 50% particle size (2D / 3 ≧) is 4.2% by volume, and SF-1 The value of was 112.
[0276]
Furthermore, the specific resistance is 8.8 × 10¹¹Ωcm, saturation magnetization is 51 Am²/ Kg.
[0277]
A toner manufacturing method will be described below.
[0278]
(Toner Production Example 1)
To 10,000 parts of ion-exchanged water in the reaction vessel, 0.1M Na_ThreePO_Four100 parts of an aqueous solution and 85 parts of a 1M HCl aqueous solution were added, and N₂The temperature was kept at 65 ° C. for 60 minutes while purging. While stirring at 12000 rpm using a TK homomixer (made by Tokushu Kika Kogyo), 1.0M-CaCl₂60 parts of the aqueous solution was added all at once to prepare an aqueous medium containing calcium phosphate having a pH of 6.5.
[0279]
on the other hand,
・ 80 parts of styrene
・ N-butyl acrylate 20 parts
・ Carbon black 12 parts
・ Metal compound of di-tert-butylsalicylate 1.0 part
・ Condensation compound 10 parts
([Saturated polyester (terephthalic acid-propylene oxide modified bisphenol A)
・ Ester wax (half-width 4 ° C, DSC peak 65 ° C) 15 parts
・ 0.25 part of cross-linking agent (divinylbenzene)
The above material was kept at 65 ° C. in a separate container, and uniformly dissolved and decomposed at 12000 rpm using a TK type homomixer (manufactured by Tokushu Kika Kogyo). In this, 3 parts by mass of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
[0280]
The polymerizable monomer composition is charged into the aqueous medium in the reaction vessel,₂Under purging, the mixture was stirred at 12000 rpm for 10 minutes with a TK homomixer to granulate the polymerizable monomer composition. Thereafter, while stirring with a paddle stirring blade, the polymerization reaction was carried out at 65 ° C. for 6 hours, the temperature was further raised to 85 ° C., the reaction was carried out for 9 hours, and distillation was carried out at 85 ° C.
[0281]
After completion of the polymerization reaction, the reaction vessel was cooled, and hydrochloric acid was added to dissolve the calcium phosphate salt, followed by filtration, washing with water and drying to obtain a black toner base (Bk1).
[0282]
The toner (Bk1) had an equivalent-circle number-average diameter of 6.3 μm, an average circularity by a flow type particle image analyzer of 0.973, and a standard deviation of the circularity of 0.033. Details are shown in Table 1.
[0283]
(Toner Production Examples 2 to 4 and 7 to 14)
The polymer particle black toner base (pigment carbon black) Bk4 to Bk5, and the yellow toner base (pigment CI, pigment) are the same as in the toner production example 1 except that the types and addition amounts of the colorant and wax component are changed. Pigment Yellow 93) Y1 to Y3, magenta toner base (pigment quinacridone) M1 to M3, and cyan toner base (pigment copper phthalocyanine) C1 to C3 were obtained. Details are shown in Table 1.
[0284]
(Toner Production Example 5)
100 parts of polyester resin obtained by condensing propoxylated bisphenol with fumaric acid and trimellitic acid
・ 8 parts of carbon black
・ Zirconium complex compound of di-alkylsalicylic acid 4 parts
・ Low molecular weight polypropylene 4 parts
The above raw materials are premixed with a Henschel mixer, melt-kneaded with a twin-screw extrusion kneader, cooled and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet type pulverizer. Crushed. Further, the obtained finely pulverized product was classified and then spheroidized by mechanical impact to obtain a black toner base material (Bk2) having a weight average particle size of 7.3 μm.
[0285]
The black toner base Bk2 had a circle-equivalent number average diameter of 6.5 μm, an average circularity of 0.962 by a flow type particle image analyzer, and a standard deviation of the circularity of 0.030. Details are shown in Table 1.
[0286]
(Toner Production Example 6)
A black toner base (Bk3) was obtained in the same manner as in Toner Production Example 5 except that the type and amount of the wax component were changed.
[0287]
The black toner base Bk3 had a circle-equivalent number average diameter of 6.5 μm, an average circularity by a flow type particle image analyzer of 0.945, and a standard deviation of the circularity of 0.037. Details are shown in Table 1.
[0288]
(Comparative toner production examples 1 to 4)
Polymer particles (Bk6 to Bk7), (Y4), (M4), and (C4) were obtained in the same manner as in Toner Production Example 1 except that the types and addition amounts of the colorant and the wax component were changed. Details are shown in Table 1.
[0289]
[Example 1]
100 parts of the black toner particles (Bk1) obtained in Toner Production Example 1 and 0.7 parts of hydrophobic silica fine particles having an average particle diameter of 0.05 μm were rotated in a Henschel mixer 10B (manufactured by Mitsui Miike Chemical Co., Ltd.). After mixing under conditions of several 3000 rpm and stirring time of 1 minute, 1.0 part of titania fine particles having an average particle diameter of 0.3 μm was added and stirred for another 3 minutes at a rotational speed of 3000 rpm. A black toner was obtained.
[0290]
At this time, the liberation rate of Si atoms relative to C atoms in the toner base was 1.4%, and the liberation rate of Ti atoms was 12.3%.
[0291]
For 7 parts of this black toner, the carrier No. A developer was prepared by mixing 93 parts of 1 and using a laser beam printer of A3 size having the configuration shown in FIG. 3 equipped with the charging roller of Production Example 1, continuous durability of 50000 images with an image area ratio of 5% A test was conducted. A solid white image and a solid black image are output as samples on the 10th and 50000th sheets in a high temperature and high humidity environment (30 ° C./80%), and halftone in a low temperature and low humidity environment (10 ° C./15%). Images were output and evaluated for fogging, density stability, image uniformity, and charging roller contamination.
[0292]
The obtained output image was very good in both fog and image density stability in a high temperature and high humidity environment (30 ° C./80%). Even in a low-temperature and low-humidity environment (10 ° C./15%), the halftone image uniformity was smooth and fine, and when the charging roller was visually observed, no contamination was confirmed.
[0293]
[Example 2]
100 parts of yellow toner particles (Y1) obtained in Toner Production Example 2, 0.7 part of hydrophobic silica particles having an average particle diameter of 0.25 μm and 1.0 part of titania fine particles having an average particle diameter of 0.3 μm Were mixed in a Henschel mixer 10B under the conditions of a rotation speed of 3000 rpm and a stirring time of 4 minutes to obtain a negatively charged yellow toner.
[0294]
At this time, the liberation rate of Si atoms relative to C atoms in the toner base was 6.3%, and the liberation rate of Ti atoms was 12.9%.
[0295]
The yellow toner was used and evaluated in the same manner as in Example 1. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0296]
[Example 3]
100 parts of the magenta toner particles (M1) obtained in Toner Production Example 3 and 0.7 part of hydrophobic silica having an average particle diameter of 0.01 μm were rotated at 3000 rpm in a Henschel mixer 10B (manufactured by Mitsui Miike Chemical Co., Ltd.). The mixture was mixed under the conditions of a stirring time of 2 minutes, and then 1.0 part of titania fine particles having an average particle diameter of 0.05 μm was added, and the mixture was further stirred for 2 minutes at a rotational speed of 3000 rpm. Got.
[0297]
At this time, the liberation rate of Si atoms with respect to C atoms in the toner base was 1.2%, and the liberation rate of Ti atoms was 22.2%.
[0298]
Using this magenta toner, evaluation was made in the same manner as in Example 1 below. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0299]
  Example 4Reference Examples 1-6]
  Evaluations were made in the same manner except that the toner particles used in Example 1 and the types and amounts of external additives, charging rollers, and carriers were changed as shown in Table 1. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0300]
  [Reference Example 7]
  In Example 1, 100 parts of magenta toner particles (M2) were used, and 0.7 parts of hydrophobized silica fine particles having an average particle diameter of 0.05 μm were added to Henschel mixer 10B (Mitsui Miike Chemical Industries Co., Ltd.) as shown below for external addition conditions. The mixture was added under the conditions of a rotation speed of 4000 rpm and a stirring time of 2 minutes, and then 1.0 part of titania fine particles having an average particle diameter of 0.3 μm was added and the mixture was further added at a rotation speed of 4000 rpm for 2 minutes. Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0301]
  [Reference Example 8]
  In Example 1, 100 parts of magenta toner particles (M3) were used, and 1.0 part of titania fine particles having an average particle diameter of 0.3 μm were added to a Henschel mixer 10B (Mitsui Miike Chemical Co., Ltd.) as shown below for external addition conditions. The mixture was added under the conditions of a rotation speed of 4000 rpm and a stirring time of 2 minutes, and then 0.7 part of hydrophobized silica fine particles having an average particle diameter of 0.05 μm were further added, and the rotation speed was further 4000 minutes. Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0302]
  [Reference Example 9]
  In Example 1, 100 parts of cyan toner particles (C2) were used, and 1.0 part of titania fine particles having an average particle size of 0.3 μm was added to a Henschel mixer 10B (Mitsui Miike Chemical Industries Co., Ltd.) as shown in the following external addition conditions. The mixture was added under the conditions of a rotation speed of 3000 rpm and a stirring time of 1 minute, and then 0.7 part of hydrophobized silica fine particles having an average particle diameter of 0.05 μm was added, and the rotation speed was further 2000 minutes. Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0303]
  [Reference Example 10]
  In Example 1, 100 parts of cyan toner particles (C3) were used, and the external addition conditions were 0.7 parts of hydrophobic silica particles having an average particle diameter of 0.05 μm and an average particle diameter of 0.3 μm as shown below. Evaluation was performed in the same manner except that 1.0 part of titania fine particles was changed to a condition of a rotation speed of 3000 rpm and a stirring time of 1 minute using a Henschel mixer 10B. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0304]
[Comparative Example 1]
In Example 1, 100 parts of black toner particles (Bk6) were used, and, as shown in the following external addition conditions, 1.0 part of titania fine particles having an average particle diameter of 0.3 μm was added to Henschel mixer 10B (Mitsui Miike Chemical Industries, Ltd.). The mixture was added under the conditions of a rotation speed of 2000 rpm and a stirring time of 1 minute, and then 0.7 part of hydrophobized silica fine particles having an average particle size of 0.05 μm were added, and the rotation speed was further 2000 minutes. Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0305]
[Comparative Example 2]
In Example 1, 100 parts of yellow toner particles (Y1) were used, and 1.0 part of titania fine particles having an average particle diameter of 0.3 μm was added to a Henschel mixer 10B (Mitsui Miike Chemical Industries Co., Ltd.) as shown in the following external addition conditions. The mixture was added under the conditions of a rotation speed of 4000 rpm and a stirring time of 5 minutes, and then 0.7 part of hydrophobized silica fine particles having an average particle size of 0.05 μm was added and the mixture was further rotated at a rotation speed of 3000 rpm for 3 minutes. Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0306]
Charge-up occurred and the image density decreased.
[0307]
[Comparative Example 3]
In Example 1, 100 parts of magenta toner particles (M4) were used. As shown below, external addition conditions were 0.7 parts of hydrophobic silica particles having an average particle diameter of 0.05 μm and an average particle diameter of 0.3 μm. Evaluation was carried out in the same manner except that 1.0 part of titania fine particles was changed to a condition of a rotational speed of 4000 rpm and a stirring time of 6 minutes using a Henschel mixer 10B. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0308]
Charge-up occurred and the image density decreased.
[0309]
[Comparative Example 4]
In Example 1, 100 parts of cyan toner particles (C4) were used, and 0.7 parts of hydrophobized silica fine particles having an average particle diameter of 0.05 μm were added to Henschel mixer 10B (Mitsui Miike Chemical Industries Co., Ltd.) as shown below for external addition conditions. And then adding 1.0 part of titania fine particles having an average particle size of 0.3 μm for another 1 minute at a rotational speed of 2000 rpm Evaluations were made in the same manner except that the stirring conditions were changed. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0310]
Significant charge-up occurred and a decrease in image density was observed.
[0311]
[Comparative Example 5]
Evaluation was made in the same manner as in Example 1 except that the toner particles and the charging roller used were changed as shown in Table 1. The physical properties of the toner are shown in Table 1, and the evaluation results are shown in Table 2.
[0312]
The explanation of the evaluation items described in the examples and comparative examples and the evaluation criteria are shown below.
[0313]
<Image fog>
The fog was measured using a REFECTOMETER MODEL TC-6DS (manufactured by Tokyo Denshoku). The black / magenta toner image was calculated with the following formula using the green filter, the yellow toner image using the blue filter, and the cyan toner image using the amber filter, and measuring the reflectance of the standard paper and solid white pattern samples. . The initial fog was evaluated using a 10-sheet sample, and the durable fog was evaluated using a 50000-sheet sample. A fogging amount of 1.5% or less is a good image with substantially no fogging, and if the fogging amount exceeds 1.5%, the fogging is an unclear image. Evaluation was ranked as follows.
[0314]
Fog (reflectance;%) = (reflectance of standard paper;%) − (reflectance of sample;%)
A: Less than 0.4%
○: 0.4% or more and less than 0.8%
Δ: Over 0.8% and less than 1.5%
×: Over 1.5%
[0315]
<Image density>
For the evaluation of image density stability, the density of a solid black pattern sample at a point 3 cm from the front end of the paper is measured at three points at the center and both ends, and an average value is obtained. Density measurement was performed with a reflection densitometer RD918 (manufactured by Macbeth). Evaluation was ranked as follows.
・ Initial concentration
A: The density of the 10th sheet is 1.45 or more
○: The density of the 10th sheet is 1.40 or more and less than 1.45
Δ: The density of the 10th sheet is 1.35 or more and less than 1.40
X: The density of the 10th sheet is less than 1.35
・ Durable concentration reduction
A: The density difference between the 10th sheet and the 50000th sheet is less than 0.1.
○: The density difference between the 10th sheet and the 50000th sheet is 0.1 or more and less than 0.2.
Δ: The density difference between the 10th sheet and the 50000th sheet is 0.2 or more and less than 0.3.
X: The density difference between the 10th sheet and the 50000th sheet is 0.3 or more.
[0316]
<Halftone image uniformity>
The evaluation of the image uniformity was judged from the obtained halftone image and the surface observation of the charging roller. The ranking of evaluation was performed as follows by visual inspection.
A: Uniformity of the halftone image is good, and the charging roller surface is also clean.
○: The uniformity of the halftone image is good, but a slight contamination can be seen on the surface of the charging roller.
Δ: Uniformity of halftone image is slightly poor, and contamination on the charging roller surface can be clearly recognized
X: The uniformity of the halftone image is poor, the density unevenness occurs in the charging roller cycle, and the contamination on the surface of the charging roller is very noticeable.
[0317]
<Drum fusion>
The evaluation of drum fusion was judged from the obtained 5% duty durable image and the surface observation of the photoreceptor. The ranking of evaluation was performed as follows by visual inspection.
A: The image has no image defects due to fusion, and the surface of the photoreceptor is clean.
○: Image has no image defects due to fusion, but a slight fusion material is seen on the photoreceptor surface
Δ: Level in which there are less than 5 image defects due to fusion on the image, and the fusion material can be clearly recognized on the surface of the photoreceptor.
X: Level in which 5 or more image defects due to fusion exist in the image, and a large number of fusion products can be recognized on the surface of the photoreceptor.
[0318]
[Table 1]

[0319]
[Table 2]

[0320]
【The invention's effect】
According to the present invention having the above-described configuration, a toner and an image forming method capable of obtaining a stable image with low fog and density without causing drum fusion even when a large number of sheets are continuously printed in a high-temperature and high-humidity environment. It was. Further, even when a large number of continuous prints were performed in a low-temperature and low-humidity environment, a toner and an image forming method having good image uniformity with little contamination on the charging roller were obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of an image forming method.
FIG. 2 is a schematic view of an image forming method.
FIG. 3 is a schematic configuration diagram of an example of an image forming apparatus according to the present invention.
FIG. 4 is a layer configuration model diagram of a photoconductor.
FIG. 5 is a layer configuration model diagram of a photoreceptor.
FIG. 6 is a layer configuration model diagram of a photoreceptor.
FIG. 7 is a layer configuration model diagram of a photoconductor.
[Explanation of symbols]
1 Photoconductor
2 Charging means
5 Transfer means
4b Development sleeve

Claims (40)

A photosensitive member, a charging unit that charges the surface of the photosensitive member, an information writing unit that forms an electrostatic latent image on the charged photosensitive member, and a developer toner is supplied to the electrostatic latent image to visualize the electrostatic latent image. And a transfer unit that transfers the visualized toner image to a transfer material, and is used in an image forming method that collects the toner remaining on the photoreceptor after the transfer process in combination with the development of the electrostatic latent image. Developer,
The charging means for charging the surface of the photoreceptor is a charging roller having a conductive elastic layer, and the number of circles corresponding to the number of circles on the basis of the number-based circle-equivalent diameter measured by a flow type particle image measuring device-roundness scattergram The charging roller has a 10-point average surface roughness (Rz) smaller than the diameter D ₁ (μm),
The developer is a two-component developer composed of a toner and a carrier, and the toner contains 0.05 to 2.5 parts by mass of silica fine particles and titania fine particles as an external additive with respect to 100 parts by mass of the toner base. 0.05 to 2.5 parts by mass, the liberation rate of Si atoms derived from the silica fine particles to C atoms derived from the base of the toner is 1.2 to 6.3 %, and the titania fine particles The liberation rate of the derived Ti atoms is 12.3 to 22.2 % ,
The average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow type particle image measuring apparatus is 0.970 to 0.995, and the circularity standard deviation is 0.015 to 0.00. A developer characterized by being less than 035 . 2. The developer according to claim 1, wherein an average particle diameter of the external additive of the toner is 0.005 to 0.8 μm. The toner is a toner containing at least a binder resin, a colorant, and a release agent, and a full width at half maximum at an endothermic peak in differential thermal analysis (DSC) of the toner is 10 ° C. or less. Item 3. The developer according to Item 1 or 2 . Developer according to any one of claims 1 to 3 endothermic peak in the DSC endothermic curve of the releasing agent contained in the toner is characterized in that it is a 50 ° C. to 120 ° C.. Developer according to any one of claims 1 to 3 endothermic peak in the DSC endothermic curve of the releasing agent contained in the toner is characterized in that it is a 60 ° C. to 100 ° C.. Developer according to any one of claims 1 to 5, wherein the weight-average molecular weight of release agent (Mw) of 300 to 1,500. Developer according to any one of claims 1 to 5 weight-average molecular weight of release agent (Mw) is characterized in that it is a 400 to 1,250. Developer according to any one of claims 1 to 7, characterized in that 10-point average surface roughness of the charging roller (Rz) is 5μm or less. Developer according to any one of claims 1 to 7, characterized in that the charging point average surface roughness surface roughness of the roller (Rz) is 3μm or less. The carrier is a magnetic material dispersion type coated carrier, and the content of particles having a 50% diameter by volume average of 15 to 60 μm and a particle diameter of 2/3 or less of the 50% particle diameter (2D / 3 ≧) The developer according to any one of claims 1 to 9 , wherein 5 is 5% by volume or less and SF-1 is 100 to 130. The carrier according to any one of claims 1 to 10 , wherein the carrier is a magnetic material-dispersed coat carrier having a core in which a metal compound is dispersed in a binder resin, and the core surface being coated with a resin. Developer. The carrier contains at least two kinds of metal compound particles, the ratio of the metal compound to the binder resin is 80 to 99% by mass, one of the metal compound particles is a ferromagnetic substance, and the other is according to any one of claims 1 to 11, wherein the ratio of the ferromagnetic against a non-magnetic metal compound having a high resistance than the ferromagnetic-metal compound particles the total amount is 50 to 95 wt% Developer. The carrier has a specific resistance of 1 × 10 ^{8 to} 1 × 10 ¹⁶ Ω · cm and a magnetization strength at 1000 / 4π (kA / m) of 20 to 100 (Am ² / kg). developer according to any one of claims 1 to 12,. Ferromagnet the carrier is magnetite, the developer according to any one of claims 1 to 13 at least one of the high-resistance metal compound characterized in that it is a hematite. Developer according to any one of claims 1 to 14 The resin binder in the carrier, characterized in that it has a crosslinked structure made of a thermosetting resin. The developer according to any one of claims 1 to 15 , wherein the binder resin in the carrier is a phenol resin. In the image forming method, a toner charge amount control unit that is located upstream of the charging unit and charges the toner on the surface of the photosensitive member, and the toner remaining on the photosensitive member after the transfer step is used as the toner. Charge amount of an absolute value smaller than the absolute value of the charge amount when the charge amount is controlled by the charge amount control means to the normal polarity and the surface of the photosensitive member is charged by the charge means, and at the same time the charge amount is charged by the toner charge amount control means. The developer according to any one of claims 1 to 16 , wherein: Developer according to any one of claims 1 to 17 the charging means is characterized by a contact charging method. Developer according to any one of claims 1 to 18 the charging means and applying an oscillating electric field. Developer according to any one of claims 1 to 19 said information writing means, characterized in that the exposure means. A photosensitive member, a charging unit that charges the surface of the photosensitive member, an information writing unit that forms an electrostatic latent image on the charged photosensitive member, and a developer toner is supplied to the electrostatic latent image to visualize the electrostatic latent image. And an image forming method for recovering toner remaining on the photoreceptor after the transfer process in combination with development of the electrostatic latent image, and a developing unit that transfers the visualized toner image to a transfer material.
The developer is a two-component developer composed of a toner and a carrier, and the toner contains 0.05 to 2.5 parts by mass of silica fine particles and titania fine particles as an external additive with respect to 100 parts by mass of the toner base. 0.05 to 2.5 parts by mass, the liberation rate of Si atoms derived from the silica fine particles to C atoms derived from the base of the toner is 1.2 to 6.3 %, and the titania fine particles The liberation rate of the derived Ti atoms is 12.3 to 22.2 % ,
The average circularity in the number-based equivalent circle diameter-circularity scattergram measured by the toner flow type particle image measuring apparatus is 0.970 to 0.995, and the circularity standard deviation is 0.015 to 0.00. Less than 035 ,
The charging means for charging the surface of the photoreceptor is a charging roller having a conductive elastic layer, and the number of circles corresponding to the number of circles on the basis of the number-based circle-equivalent diameter measured by a flow type particle image measuring device-circularity scattergram An image forming method for developing and collecting, wherein the charging roller has a 10-point average surface roughness (Rz) smaller than a diameter D ₁ (μm). The image forming method according to claim 21, wherein an average particle diameter of the external additive of the toner is 0.005 to 0.8 µm. The toner is a toner containing at least a binder resin, a colorant, and a release agent, and has a half-value width of 10 ° C. or less at an endothermic peak of differential thermal analysis (DSC) of the toner. Item 23. The image forming method according to Item 21 or 22 . The image forming method according to any one of claims 21 to 23 , wherein an endothermic peak value in a DSC endothermic curve of the release agent contained in the toner is 50 ° C to 120 ° C. The image forming method according to any one of claims 21 to 23 , wherein an endothermic peak value in a DSC endothermic curve of the release agent contained in the toner is 60 ° C to 100 ° C. The image forming method according to any one of claims 21 to 25 weight average molecular weight of release agent (Mw) is characterized in that it is a 300 to 1,500. The image forming method according to any one of claims 21 to 25 weight average molecular weight of release agent (Mw) is characterized in that it is a 400 to 1,250. The image forming method according to any one of claims 21 to 27, characterized in that 10-point average surface roughness of the charging roller (Rz) is 5μm or less. 10-point average surface roughness the surface roughness of the charging roller (Rz) is an image forming method according to any one of claims 21 to 27, characterized in that it is 3μm or less. The carrier is a magnetic material-dispersed coated carrier, and the content of particles having a 50% diameter by volume average of 15 to 60 μm and a particle size of 2/3 or less of the 50% particle diameter (2D / 3 ≧) There 5 vol% or less, the image forming method according to any one of claims 21 to 29 SF-1 is characterized in that it is a 100 to 130. The carrier according to any one of claims 21 to 30 , wherein the carrier is a magnetic material-dispersed coated carrier having a core in which a metal compound is dispersed in a binder resin and the core surface is coated with a resin. Image forming method. The carrier contains at least two kinds of metal compound particles, the ratio of the metal compound to the binder resin is 80 to 99% by mass, one of the metal compound particles is a ferromagnetic substance, and the other is according to any one of claims 21 to 31, wherein the ratio of the ferromagnetic against a non-magnetic metal compound having a high resistance than the ferromagnetic-metal compound particles the total amount is 50 to 95 wt% Image forming method. The carrier has a specific resistance of 1 × 10 ^{8 to} 1 × 10 ¹⁶ Ω · cm and a magnetization strength at 1000 / 4π (kA / m) of 20 to 100 (Am ² / kg). the image forming method according to any one of claims 21 to 32 and. 34. The image forming method according to claim 21, wherein the ferromagnetic material in the carrier is magnetite, and at least one of the high resistance metal compounds is hematite. The image forming method according to any one of claims 21 to 34 The resin binder in the carrier, characterized in that it has a crosslinked structure made of a thermosetting resin. The resin binder in the carrier, the image forming method according to any one of claims 21 to 35, characterized in that a phenolic resin. In the image forming method, a toner charge amount control unit that is located upstream of the charging unit and charges the toner on the surface of the photoconductor, and the toner remaining on the photoconductor after the transfer step is used as the toner. A charge amount having an absolute value smaller than the absolute value of the charge amount when the charge amount is controlled to a normal polarity by the charge amount control unit, and the surface of the photosensitive member is charged by the charging unit, and at the same time the charge amount is charged by the toner charge amount control unit. 37. The image forming method according to any one of claims 21 to 36 , wherein: The charging means image forming method according to any one of claims 21 to 37, characterized in that a contact charging method. The charging means image forming method according to any one of claims 21 to 38, characterized in applying an oscillating electric field. The image forming method according to any one of claims 21 to 39 said information writing means, characterized in that the exposure means.

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