JP2004126239A - Toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner with which a stable favorable image having no fog can be obtained for a long period of time without causing problems of contamination in an electrifying member or scratches on a photoreceptor even in an environmentally conscious system into which processes of ozone-less contact electrification and simultaneous developing and cleaning are introduced. <P>SOLUTION: The toner composition to be used for an image forming method including contact electrification and cleaner-less processes consists of an additive and toner particles containing at least a coloring agent and a binder resin. The additive is a titanium compound prepared by surface treating metatitanic acid with a silane compound or silicone oil. <P>COPYRIGHT: (C)2004,JPO

Description

【０１５２】
【数２】

【０１５３】
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。
【０１５４】
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。
【０１５５】
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。
【０１５６】
【数３】

【０１５７】
【数４】

【０１５８】
又、円形度頻度分布の平均値を意味する平均円形度Ｃと円形度標準偏差ＳＤｃは、粒度分布の分割点ｉでの円形度（中心値）をｃｉ、頻度をｆ_ｃｉとすると、次式から算出される。
【０１５９】
【数５】

【０１６０】
（疎水化度測定）
メタノール滴定試験は、疎水性無機微粒子の疎水化度を確認する実験的試験である。疎水性無機微粒子０．２ｇを容量２５０ｍｌの三角フラスコ中の水５０ｍ１に添加する。メタノールをヒューレットから疎水性無機微粒子の全量が湿潤されるまで滴定する。この際フラスコ内の溶液はマグネチックスターラーで常時撹拌する。その終点は疎水性無機微粒子の全量が液体中に懸濁されることによって観察され、疎水化度は終点に達した際のメタノールおよび水の液状混合物中のメタノール百分率として表わされる。
【０１６１】
（ＢＥＴ比表面積の測定方法）
疎水性無機微粒子のＢＥＴの実測は次のようにして行う。
【０１６２】
ＢＥＴ比表面積は、湯浅アイオニクス（株）製、全自動ガス吸着量測定装置：オートソーブ１を使用し、吸着ガスに窒素ガスを用い、ＢＥＴ多点法により求める。なお、サンプルの前処理としては、温度５０℃で１０時間の脱気を行う。
【０１６３】
（疎水性無機微粒子の平均粒径の測定方法）
一次粒子径は、疎水性無機微粒子を透過電子顕微鏡で観察し、視野中の１００個の粒子径を測定して平均粒子径を求める。
【０１６４】
【実施例】
以下、実施例によって本発明を具体的に説明するが、本発明は何らこれの実施例に制約されるものではない。「部」は「質量部」を意味する。
【０１６５】
疎水性メタチタン酸Ａの製造例
硫酸加水分解法により得られた個数平均一次粒径が４０ｎｍのメタチタン酸スラリーに撹幹しながら６Ｎ水酸化ナトリウム水溶液を加えｐＨ８．５として１時間撹拌保持後、１２Ｎ塩酸にてｐＨ５．６まで中和し、ろ過、水洗を行った。洗浄済ケーキに水を加え再びスラリーとし、撹拌をしながら１２Ｎ塩酸を加えｐＨｌ．３とし２時間撹拌保持し、解膠処理を行った。この解膠スラリーからメタチタン酸として１００ｇ分を分取し、４０℃に加温保持し撹拌しながら、イソブチルトリメトキシシラン５０ｇ（５０質量％）を添加し３０分間撹拌保持した。次に一旦反応スラリーに８Ｎ水酸化ナトリウム水溶液を加えｐＨを９．８（４０℃）にし、１０分間撹拌保持後、８Ｎ塩酸を用いてｐＨ６．６（４０℃）まで中和し、ろ過、水洗を行った。
【０１６６】
水洗済ケーキは１３０℃で乾燥した後、エアジェット方式による微粉砕機で微粉砕し、ＳｉＯ_２量１１質量％、トルエン抽出によるＣ量減少率１２％、ＳｉＯ_２量減少率１２％、疎水化度５７％、ＢＥＴ比表面積１２０ｍ^２／ｇの目的とする疎水性メタチタン酸微粒子（疎水性メタチタン酸Ａ）を得た。
【０１６７】
疎水性メタチタン酸Ｂの製造例
硫酸加水分解法により得られた個数平均一次粒径が３０ｎｍのメタチタン酸スラリーに撹拌しながら６Ｎ水酸化ナトリウム水溶液を加えｐＨ９．３として１時間撹拌保持後、１２Ｎ塩酸にてｐＨ５．５まで中和し、ろ過、水洗を行った。洗浄済ケーキに水を加え再びスラリーとし、撹拌をしながら１２Ｎ塩酸を加えｐＨ１．２とし２時間撹拌保持し、解膠処理を行った。この解膠スラリーからメタチタン酸として１００ｇ分を分取し、４０℃に加温保持し撹拌しながら、イソブチルトリメトキシシラン１０ｇ（１０質量％）を添加し３０分間撹拌保持した。次に一旦反応スラリーに８Ｎ水酸化ナトリウム水溶液を加えｐＨを９．６（４０℃）にし、１０分間撹拌保持後、８Ｎ塩酸を用いてｐＨ６．５（４０℃）まで中和し、ろ過、水洗を行った。
【０１６８】
水洗済ケーキは１３０℃で乾燥した後、エアジェット方式による微粉砕機で微粉砕し、ＳｉＯ_２量５質量％、トルエン抽出によるＣ量減少率１０％、ＳｉＯ_２量減少率１０％、疎水化度３５％、ＢＥＴ比表面積１３０ｍ^２／ｇの目的とする疎水性メタチタン酸微粒子（疎水性メタチタン酸Ｂ）を得た。
【０１６９】
疎水性メタチタン酸Ｃの製造例
イソブチルトリメトキシシランの添加量を９０ｇ（９０質量％）に変えた以外は、外添剤Ｂと同様な手法を用いてＳｉＯ_２量１８質量％、トルエン抽出によるＣ量減少率１７％、ＳｉＯ_２量減少率１４％、疎水化度９５％、ＢＥＴ比表面積１４０ｍ^２／ｇの疎水性メタチタン酸微粒子（疎水性メタチタン酸Ｃ）を得た。
【０１７０】
疎水性メタチタン酸Ｄの製造例
硫酸加水分解法により得られるメタチタン酸スラリーを、ｐＨ調整により個数平均一次粒径が１２０ｎｍのものを用い、イソブチルトリメトキシシランの添加量を４０ｇ（４０質量％）に変えた以外は、外添剤Ａと同様な手法でＳｉＯ_２量８質量％、トルエン抽出によるＣ量減少率１２％、ＳｉＯ_２量減少率１２％、疎水化度５５％、ＢＥＴ比表面積３０ｍ^２／ｇの疎水性メタチタン酸微粒子（疎水性メタチタン酸Ｄ）を得た。
【０１７１】
疎水性メタチタン酸Ｅの製造例
疎水性メタチタン酸Ａの製造例において、イソブチルトリメトキシシランの添加量を７０ｇ（７０質量％）に変え、３０分撹拌保持後、８Ｎ水酸化ナトリウム水溶液を加えてそのままｐＨ６．５（４０℃）まで中和する以外は同様な手法を用いてＳｉＯ_２量１３質量％、トルエン抽出によるＣ量減少率２０％、ＳｉＯ_２量減少率１７％、疎水化度６０％、ＢＥＴ比表面積１３０ｍ^２／ｇの疎水性メタチタン酸微粒子（疎水性メタチタン酸Ｅ）を得た。
【０１７２】
疎水性メタチタン酸Ｆの製造例
疎水性メタチタン酸Ａの製造例において、イソブチルトリメトキシシランの代わりにポリジメチルシロキサンエマルジョンを有効成分として２０ｇ（２０質量％）に変えた以外は同様な手法を用いて、ＳｉＯ_２量１５質量％、トルエン抽出によるＣ量減少率２２％、ＳｉＯ_２量減少率１７％、疎水化度５５％、ＢＥＴ比表面積７０ｍ^２／ｇの疎水性メタチタン酸微粒子（疎水性メタチタン酸Ｆ）を得た。
【０１７３】
親水性酸化チタンＧの製造例
メタチタン酸Ａの製造例において、イソブチルトリメトキシシランを使用しない以外は同様にして、未処理の親水性のアナターゼ型酸化チタンＧを得た。
【０１７４】
（トナー粒子の製造例１）
・スチレン　　　　　　　　　　　　　　　　　　　　　　　　　　　１００部
・メチルメタクリレート　　　　　　　　　　　　　　　　　　　　　　１０部
・ｎ−ブチルアクリレート　　　　　　　　　　　　　　　　　　　　　１０部
・Ｃ．Ｉ．ピグメントイエロー７４　　　　　　　　　　　　　　　　　　８部
・ジターシャリブチルサルチル酸Ａｌ化合物　　　　　　　　　　　　１．５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、酸価１４ｍｇＫＯＨ／ｇ、ピーク分子量８５００）　　　　　　　１０部
・エステルワックス（ベヘン酸ベヘニル）　　　　　　　　　　　　　　４０部
上記処方を６０℃に加温し、ＴＫホモミキサー（特殊機化工業製）を用い、１０，０００ｒｐｍにて均一に溶解、分散した。これに、重合開始剤２，２’−アゾビス（２，４−ジメチルバレロニトリル）５部を溶解し、重合性単量体組成物を調製した。
【０１７５】
別途イオン交換水７１０ｇに、０．１Ｍ−Ｎａ_３ＰＯ_４水溶液４５０部を投入し、６０℃に加温した後、ＴＫホモミキサー（特殊機化工業製）を用い、１，３００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ_２水溶液６８部を徐々に添加し、Ｃａ_３（ＰＯ_４）_２を含む水系媒体を得た。
【０１７６】
この水系媒体中に上記重合性単量体組成物を投入し、更にポリエチレンを２部添加し、６０℃，Ｎ_２雰囲気下において、クレアミキサーにて１２，０００ｒｐｍで１０分間撹拌し、重合性単量体組成物を造粒した。その後、水系媒体をパドル撹拌翼で撹拌しつつ、８０℃で昇温し、８時間の重合反応を行った。
【０１７７】
重合反応終了後、冷却し、塩酸を加えリン酸カルシウムを融解させた後、濾過、水洗、乾燥をして、重合粒子（トナー粒子１）を得た。得られた重合トナー粒子Ａの重量平均粒径は６．７μｍ、平均円形度は０．９８０、円形度標準偏差は０．０３２であった。
【０１７８】
得られたトナー粒子１は、透過電子顕微鏡（ＴＥＭ）を用いた重合粒子の断層面測定法により、ワックスを外殻樹脂層で内包化したコア−シェル構造が確認された。
【０１７９】
（トナー粒子の製造方法２）
Ｃ．Ｉ．ピグメントイエロー７４の変わりにキナクリドン顔料を使用することを除いては、トナー粒子１の製造例と同様にしてマゼンタ色の重合粒子（トナー粒子２）を得た。得られたトナー粒子２は、重量平均粒径６．７μｍ、平均円形度は０．９７９円形度標準偏差は０．０３４であった。
【０１８０】
（トナー粒子の製造例３）
Ｃ．Ｉ．ピグメントイエロー７４の変わりにＣ．Ｉ．ピグメントブルー１５：３を使用することを除いては、トナー粒子１の製造例と同様にしてシアン色の重合粒子（トナー粒子３）を得た。得られたトナー粒子３は、重量平均粒径６．７μｍ、平均円形度は０．９８１、円形度標準偏差は０．０２９であった。
【０１８１】
（トナー粒子の製造例４）
Ｃ．Ｉ．ピグメントイエロー７４の変わりにカーボンブラックを使用することを除いては、トナー粒子１の製造例と同様にしてブラック色の重合粒子（トナー粒子４）を得た。得られたトナー粒子４は、重量平均粒径６．８μｍ、平均円形度は０．９８０、円形度標準偏差は０．０３１であった。
【０１８２】
＜実施例１＞
トナーの粒子の製造例４で得られたブラック粒子１００部に対して、疎水性メタチタン酸Ａを１．２部加えて、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、攪拌時間３分間の条件下で混合し、ブラックトナーを得た。
【０１８３】
上記トナー８部と、フェノール樹脂中にマグネタイト粒子を分散してなる磁性微粒子分散型樹脂キャリア９２部とを混合し二成分現像剤とし、画像形成装置として、市販のデジタル複写機ＧＰ５５（キヤノン製）を図３の現像装置が入れるよう改造したものを用いた。具体的には、現像剤担持体としては直径１６ｍｍのＳＵＳスリーブをサンドブラスト処理によって表面粗さＲｚ＝１２．５μｍに調整したものを使用した。帯電部材としては、図１に示す帯電器を使用し、感光体の当接部に対して順方向に１００％で回転させ、直流／交流電界（−６００Ｖ、１．５ｋＨｚ／１．２ｋＶｐｐ）を重畳印加し、を帯電させた。現像コントラストは−２００Ｖ、バックコントラストを−２００Ｖに設定し、不図示のバイアス印加手段から図４に示す交流電圧を有する現像バイアスを印加し、定着ローラー、加圧ローラーともに表層をＰＦＡで１．２μｍ被覆したローラーに変更しオイル塗布機構を除去した構成に改造し、画像面積５％のオリジナル原稿を使用し、１５℃／１０％（Ｌ／Ｌ）、３０℃／８０％（Ｈ／Ｈ）の各環境でそれぞれ１万枚の通紙試験を行い、以下の評価法に基づいて評価した。結果を表１に示すが、表から分かるように良好な結果が得られた。
【０１８４】
（画像濃度）
画像濃度は、ＳＰＩフィルターを装着したマクベス社製マクベスデンシトメータＲＤ９１８タイプ（Ｍａｃｂｅｔｈ　Ｄｅｎｓｉｔｏｍｅｔｅｒ　ＲＤ９１８ｍａｎｕｆａｃｔｕｒｅｄ　ｂｙ　Ｍａｃｂｅｔｈ　Ｃｏ．）を使用して、普通紙上に２０φのベタパッチ（オリジナル原稿濃度１．５）を５ヶ所形成し、平均画像濃度として測定した。
【０１８５】
（カブリ）
画出し前の普通紙の平均反射率Ｄｒ（％）をリフレクトメーター（東京電色株式会社製の「ＲＥＦＲＥＣＴＯＭＥＴＥＲ　ＭＯＤＥＬ　ＴＣ−６ＤＳ」）によって測定した。一方、普通紙上にベタ白画像を画出しし、次いでベタ白画像の反射率Ｄｓ（％）を測定した。カブリ（％）は下記式
Ｆｏｇ（％）＝Ｄｒ（％）−Ｄｓ（％）
から算出する。
【０１８６】
（ハーフトーン画像均一性）
マクベス画像濃度０．３〜０．６のハーフトーン画像を出力し、濃度の均一性、がさつき感、及び画像欠陥の程度を目視により評価する。
◎：画像濃度の均一性に優れた良好な出力画像である。
○：画像濃度の均一性にやや欠けるが、実用上問題のないレベルである。
△：画像濃度の均一性が悪く、がさついた出力画像であり、実用上問題となるレベルである。
×：画像濃度の均一性が著しく悪く、帯電ローラ汚染に起因するスジ又はポチ状の画像欠陥が目立ち、実用不可能なレベルである。
【０１８７】
＜実施例２＞
実施例１において疎水性メタチタン酸Ａが疎水性メタチタン酸Ｂである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように若干耐久性に劣るものの、良好な結果が得られた。これは、疎水化度が小さいことからもわかるように、表面処理が若干不均一となり、トナーへの帯電安定化効果が若干損われたためと推測される。
【０１８８】
＜実施例３＞
実施例１において疎水性メタチタン酸Ａが疎水性メタチタン酸Ｃである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、すべての評価項目において、実施例１や２と比較して若干劣るが、これは、疎水化度が大きいために、トナーの帯電速度が逆に低下したためと考えられる。
【０１８９】
＜実施例４＞
実施例１において疎水性メタチタン酸Ａが疎水性メタチタン酸Ｄである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、すべての評価項目において若干劣るが、これは粒径が大きいために、トナーの流動性が若干低下したためと推測される。
【０１９０】
＜実施例５＞
実施例１において疎水性メタチタン酸Ａが疎水性メタチタン酸Ｅである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、すべての評価項目において耐久性が若干劣るが、これは抽出量が若干大きいために、耐久によるストレスが加わった際に、疎水性メタチタン酸微粒子表面から多量の残存物が遊離したため、トナーが好適な帯電性を維持できず、キャリアへのスペントや、現像器各部を汚染したためと考えられる。
【０１９１】
＜実施例６＞
実施例１において疎水性メタチタン酸Ａが疎水性メタチタン酸Ｆである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、全ての項目において若干劣るものの良好な結果が得られた。これは、酸化チタンの処理がシリコーンオイルであるので凝集しやすく、現像剤の流動性が若干劣るためによるものと考えられる。
【０１９２】
＜実施例７＞
トナーの製造例１、トナーの製造例２、トナーの製造例３およびトナーの製造例４において得られたイエロー、マゼンタ、シアンおよびブラックトナー粒子それぞれについて、実施例１と同様の条件で外添を行い、各色のトナーを得た。
【０１９３】
また、このトナー８部に対し、キャリアの製造例で作製された磁性体分散型樹脂キャリア９２部を混合して現像剤を調製し、この現像剤２５０ｇを各色ごとに図３に示した現像器に充填し、４色のプロセストナーカートリッジとした。
【０１９４】
以上のカートリッジを用いて、１５℃／１０％（Ｌ／Ｌ）、３０℃／８０％（Ｈ／Ｈ）の各環境下において、実施例１と同様の評価方法に基づき、図２に示したフルカラー画像形成装置によって、プリント速度をＡ４横２３枚／分とし、紙面積に対するプリント比率５％のオリジナル原稿を用いて、１万枚の連続プリント試験を行った。　評価結果を表１に示が、表から分かるように、全ての項目において良好な結果が得られた
【０１９５】
＜比較例１＞
実施例１において疎水性メタチタン酸Ａが親水性酸化チタンＧである他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、すべての評価項目において悪化した。これは、疎水化処理を施してない為に、水分吸着による帯電付与性が著しく劣るともに、キャリアや帯電ローラ及び感光体への付着性も高いため、かぶりの悪化及び帯電ローラへの汚染による画像不良が顕著になったものと推測する。
【０１９６】
＜比較例２＞
実施例１において疎水性メタチタン酸Ａのかわりに、４塩化チタンから気相法で合成した後、シランカップリング剤処理したＴ８０５（デグサ社製）を用いる他は同様に行い、画像評価した。結果を表１に示すが、表から分かるように、耐久後半のかぶり及び帯電ローラ汚染による不良画像が発生した。かぶりの悪化は、気相法により製造した酸価チタンであるため処理剤の化学結合性がメタチタン酸より弱いため、耐久後半の処理剤剥離によってトナーの帯電特性がおちたためと推測する。帯電ローラへの汚染は、酸化チタン中の焼結塊の存在が、耐久に伴って帯電ローラに蓄積されたためと推測する。
【０１９７】
【表１】

【０１９８】
【発明の効果】
本発明によれば、オゾンレス接触帯電及び現像同時クリーニング工程を導入した環境に配慮したシステムにおいても、帯電部材汚染及び感光体傷の問題が生じず、長期にわたってカブリの無い安定した良好な画像が得られるトナーが提供できる。
【図面の簡単な説明】
【図１】接触帯電装置の概略図である。
【図２】フルカラー画像形成方法の例を示す概略説明図である。
【図３】本発明の現像装置の好適な一例を表す模式図である。
【図４】実施例で用いた交流電界を表す模式図である。
【図５】本発明に用い得る接触一成分現像方式のプロセスカートリッジである。
【符号の説明】
１　感光体
２　帯電部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, or the like. More specifically, the present invention relates to a toner used in a copying machine, a printer, or a facsimile, which forms a toner image on an electrostatic latent image carrier and transfers the toner image onto a transfer material to form an image.
[0002]
[Prior art]
At present, as an image forming method used in a copying machine, a method generally called an electrophotographic method is widely known. The image forming method using the electrophotographic method is also used for a printer, which is an output device of a computer, in addition to the copying machine. In the image forming method in the electrophotographic method, roughly, first, the surface of a photoreceptor is uniformly charged, an electrostatic latent image is formed on the charged photoreceptor surface by light image exposure, and toner is applied to the latent image. This is a method of forming a final image by development by attaching the toner. Thereafter, the formed image (toner image) is transferred to plain paper or the like, and then fixed. After the transfer, untransferred toner is removed from the photoreceptor surface by a cleaning unit.
[0003]
In the electrophotographic method, various types of image forming apparatuses and image forming methods have been developed depending on a charging method, a light image exposing method, a transfer / fixing method, a method of collecting untransferred toner, and a developer used. I have. For example, the charging method includes a method using corona discharge, a method using a magnetic brush with a charging roller, a contact charging method in which the charging roller is brought into direct contact, and the like, which have been widely used. Also, in the light image exposure method, for example, a method of exposing a light image from a surface of a photoreceptor, which is generally widely used, and a method of exposing the photoreceptor surface by exposing from the back surface of a recently developed transparent photoreceptor. A known back exposure method is known. In addition, various light sources have been developed for light image exposure, such as flash lamps for full-surface exposure, halogen lamps and fluorescent lamps for slit exposure for copiers, and semiconductor laser light for printers. , A light emitting diode (LED), a fluorescent lamp controlled by a liquid crystal shutter, and the like.
[0004]
The shape of the photoreceptor includes a drum-shaped one generally used widely, a belt-shaped one used in a feed developing method and the like, and an inorganic photoreceptor using a photosensitive layer of selenium or the like as a photosensitive layer. And various organic photoconductors using an organic photoconductive substance such as polyvinylcarbazole (PVK). In the transfer / fixing method, as a charging method at the time of transfer, there are a method using the corona discharge, a contact charging method using a conductive roller, and the like. Further, the fixing method includes a pressure fixing method, a heat roll fixing method, and a flash fixing method. Various types such as an oven fixing method and the like have been developed. The method of collecting untransferred toner after transfer is a widely used method of scraping untransferred toner from the surface of the photoreceptor after transfer using a cleaner blade, and a recently developed method of collecting untransferred toner with a developing device. And a cleaner-less system.
[0005]
However, in recent years, when resource conservation on a global scale, protection and maintenance of the global environment, and the like have been demanded, development from a new viewpoint different from the past has become particularly important. In the field of office equipment such as copiers as well, from the aspect of environmental pollution, the development of image forming devices and image forming methods that incorporate not only conventional functions and price emphasis but also conventional components with the aim of eliminating pollution. It has been demanded.
[0006]
In accordance with the trend of the times, image forming methods in the electrophotographic method in consideration of ecology include ozone-less charging by introducing a contact charging method in a charging step, and transfer residual toner in a developing step without a cleaning step. A system has been developed that does not generate waste toner by collecting waste toner.
[0007]
It is said that ozone is generated due to aerial discharge in an electrophotographic method using a charging method using corona discharge which has been widely used in the past. Ozone has a strong oxidizing power and is highly toxic. Therefore, the generation of ozone in a limited office space hasten the deterioration of peripheral components and greatly affects human health. For this reason, appropriate measures against ozone have been eagerly desired.
[0008]
Therefore, as a measure for suppressing the generation of ozone, a contact charging means that does not use a corona discharger has been developed. Specifically, a voltage is applied to a conductive roller serving as a charging member, and the roller is brought into contact with a photosensitive member serving as a charged member to charge the surface of the photosensitive member to a predetermined potential. If such a contact charging means is used, a lower voltage can be achieved as compared with a corona discharger, and the amount of generated ozone can be reduced.
[0009]
For example, in Patent Document 1, a low voltage can be applied when charging photosensitive paper by using a roller in which a core metal is coated with a dielectric material made of nylon or polyurethane rubber.
[0010]
On the other hand, in the conventional photoconductor cleaning process, the untransferred toner after the transfer uses blade cleaning, fur brush cleaning, roller cleaning, and other means. The transfer residual toner is scraped off or dammed, and the transfer residual toner is collected in a waste toner container, and then collected and discarded at a later date. From the viewpoint of ecology, a system that does not generate waste toner is expected. .
[0011]
Therefore, in order to reduce the frequency of collecting and disposing of toner as much as possible and to use the developer efficiently, the untransferred toner is collected by a developing device, and the collected toner is further transported to the surface of the photoreceptor so that the toner can be recycled. A cleaner-less system that can be used has been proposed.
[0012]
However, when using environmentally friendly ozone-less contact charging and development simultaneous cleaning technology, poor charging due to fogging toner and transfer residual toner contamination of the charging member, deterioration toner accumulated due to durability and changes in temperature and humidity, and free external additives There are problems such as photoreceptor filming caused by the agent and deterioration of image quality due to scratches.
[0013]
Therefore, various measures have been attempted to improve the above problems. For example, as a countermeasure against the contact charging member, an elastic layer or a release layer is provided on the surface layer of the charging member. On the other hand, as a countermeasure against the photoreceptor, for example, Patent Document 2 proposes to prevent filming by making the surface of the photoreceptor uniform with a uniformizing member. Certainly, the above-mentioned measures have significantly reduced the phenomenon of sticking to the member to be charged and filming of the photosensitive member, but in order to achieve a stable charging process over a long period of time and in various environments, it is necessary to improve the toner. Proved difficult.
[0014]
Accordingly, as a toner for realizing a stable and high-quality image forming method in a contact charging and cleanerless system, importance has been placed on the price and functional aspects of conventional high image quality, high speed, miniaturization, low price, etc. From the idea, toners designed and developed mainly are insufficient, and are required to be particularly excellent in fluidity, transferability, developability and charge stability.
[0015]
In order to satisfy the above-mentioned characteristics, it has been conventionally used to add an inorganic oxide fine powder such as silica to a toner. However, in the case of a silica-based fine powder that is generally used, although the toner fluidity improving effect is particularly excellent, the negative polarity is strong, and the charge of the negatively chargeable toner is excessively increased particularly under low temperature and low humidity. Even if the charge is suppressed by a nitrogen compound treatment or the like, it is not suitable for the toner, and under high temperature and high humidity, water is taken in to reduce the chargeability, so that a large difference is caused between the two. As a result, the transferability and chargeability of the toner on the developer carrying member cannot be optimized at both high temperature and high humidity and low temperature and low humidity, and image density reproduction failure, background fog, toner There has been a problem that it may fall off and further cause in-flight contamination or the like.
[0016]
It has been proposed to use a surface-treated inorganic fine powder for the purpose of improving these. For example, Patent Literature 3, Patent Literature 4, Patent Literature 5, and the like describe that the surface of silica fine particles is subjected to a hydrophobic treatment.
[0017]
However, the use of these inorganic fine powders alone does not provide a sufficient effect particularly on the chargeability, and particularly in cases where sufficient chargeability can be imparted at high temperature and high humidity, excessive charge at low temperature and low humidity. Is imparted, the transport amount on the developer carrying member becomes excessive, and the broadening of charging becomes severe, and in particular, the developing property may be lowered and the degree of fogging may become severe.
[0018]
Further, as a method of relaxing the negative chargeability of the toner particles, a method of externally adding the above-mentioned silica fine particles surface-treated with aminosilane (Patent Document 6) is known. However, although treatment with these amino compounds can suppress the excessive increase in charge of the negatively chargeable toner particularly at low temperature and low humidity, it cannot sufficiently improve the environmental dependency of the silica fine powder itself. That is, even under high temperature and high humidity, similar charge neutralization occurs, so that the environment dependency is not improved as before, and background fog and image density decrease due to poor conveyance and poor charging are caused.
[0019]
As described above, even if the silica fine particles are subjected to a hydrophobic treatment, a treatment for alleviating negative chargeability, etc., the environmental dependency of the charge of silica, the charge speed, the charge distribution has not been improved. Is the current situation. In addition, when the inorganic oxide to be added for the purpose of charging and fluidity is a commonly used titanium oxide, the charge rises quickly with respect to silica, and the charge distribution is sharp, probably because of the low resistance of titanium oxide. It has the characteristic of becoming. However, in the case where titanium oxide is added, high charge cannot be imparted to the toner, so that the transport amount is reduced, the density reproducibility is reduced due to the reduced charge, and the background fog is likely to occur.
[0020]
For the purpose of improving the chargeability, a method has been proposed in which hydrophobic titanium oxide is externally added to a toner irrespective of a two-component system or a one-component system (Patent Document 7, Patent Document 8, etc.). Hydrophobic titanium oxide can be obtained by treating the surface with a silane compound, a silane coupling agent, silicone oil, or the like. According to the present method, the chargeability can be certainly increased with respect to the untreated hydrophilic titanium oxide, and it is used for two-component toners and magnetic one-component toners, and there are examples in which it is marketed. However, although this method can improve the charge level to some extent depending on the type and amount of the treating agent, the charge level is not yet at a satisfactory level, and there is a limit in environmental dependency. In addition, by increasing the hydrophobicity of titanium oxide with a treatment agent, the charge level and environmental dependency are certainly better than conventional hydrophilic titanium oxide, but titanium oxide is more effective than silica. Achieving the above properties with a low surface activity and a small amount of a treating agent has not yet reached a satisfactory level.
[0021]
Titanium oxide is mainly obtained from a method of extracting titanium oxide crystals from a ilmenite ore by a sulfuric acid method or a hydrochloric acid method.However, since titanium oxide is purified by a wet method and obtained by heating and calcining, it is subjected to dehydration condensation. The resulting chemical bonds are of course present, and existing techniques do not easily redisperse such aggregated particles. That is, the titanium oxide taken out as a fine powder formed secondary and tertiary aggregation, and the effect of improving the fluidity of the toner was significantly inferior to silica. In recent years, in particular, the demand for high image quality such as color has been increasing in the market, and attempts have been made to achieve high image quality by reducing the particle size of the toner. This phenomenon is remarkable. In addition, titanium oxide which has been conventionally used has a drawback that it does not firmly adhere to the toner surface and is easily detached from the toner surface, probably because of its large specific gravity with respect to silica. For this reason, long-term charging stability accompanied by sleeve contamination is inferior, and contamination of the photoreceptor is easily caused, which causes image quality deterioration and image quality defects.
[0022]
In order to achieve both improvement in fluidity and environmental dependency of charging, an attempt has been made to add hydrophobic titanium oxide and hydrophobic silica in combination (Patent Document 9). This technique temporarily suppresses the respective disadvantages of the hydrophobic silica and the hydrophobic titanium oxide, but is susceptible to either additive depending on the dispersion state. In particular, when considering the maintainability, it is difficult to stably control the dispersion structure on the toner surface, and the characteristics of hydrophobic silica or hydrophobic titanium oxide tend to appear due to stress on the sleeve. That is, it has been difficult to stably control the respective disadvantages over a long period of time.
[0023]
Next, a method of adding hydrophobic amorphous titanium oxide to a toner has been proposed (Patent Document 10). Amorphous titanium oxide can be obtained by hydrolyzing a metal alkoxide or a metal halide using a CVD method (Non-Patent Document 1). However, although titanium oxide obtained by the hydrolysis method can achieve both charging characteristics and improvement in toner fluidity, it has a large amount of adsorbed water inside the particles and remains on the photoreceptor itself during transfer. That is, the adhesive force between the amorphous titanium oxide and the photoreceptor is strong, and only that is left on the photoreceptor without being transferred, causing defects such as white spots on an image or scratching on the photoreceptor with hard titanium oxide during cleaning. Have.
[0024]
Also, a method has been proposed in which metatitanic acid is prepared by a wet method, and hydrophobic metatitanic acid surface-treated with an organic silane compound is externally added to the toner while mixing is suppressed without heating and baking steps. (Patent Document 11). However, in this method, although it is possible to obtain a hydrophobic metatitanic acid with suppressed aggregation, the reaction between the metatitanic acid and the silane compound is insufficient, and the amount of the silane compound to be treated is large. Self-condensation without a hydrolysis reaction with metatitanic acid increases the number of silane compounds that are only physically adsorbed on the metatitanic acid surface. For this reason, continuous development is performed for a long time, and when a stress is applied to the toner by a charging member such as a carrier, the silane compound is detached from the hydrophobic metatitanic acid surface, and a predetermined hydrophobic function cannot be maintained, or It has been found that the detached silane compound adheres or damages the surface of the electrostatic image carrier, further contaminates the charging member and the like, makes it impossible to obtain a desired charge amount, and makes it impossible to obtain a high-quality image. .
[0025]
In recent years, demands for higher definition and higher image quality of color copiers and color printers have been increasing in the market, as well as higher productivity due to higher speed. In response to such demands, when these inorganic oxides are added to the toner surface, stress is applied to the toner by the layer forming member or the like due to long-term continuous use, and toner filming and fusion to the layer forming member may occur. In addition, since the toner charging property changes due to peeling or embedding of the external additive, it becomes difficult to maintain stable toner charging and conveyance for a long period of time. In order to solve these problems, Patent Documents 12 and 13 propose to use a specific binder resin to prevent embedding of an external additive. Further, Patent Documents 14, 15, 15 and 16 propose using specific charge control agents and external additives. However, these effects are not all satisfactory. Particularly, when a large number of continuous copies are made by an electronic copying machine using a two-component developer, images that are clear and good at the beginning can be changed to tens of thousands of copies. Fog significantly increases fog, resulting in an image having poor gradation and sharpness.
[0026]
That is, when a large number of sheets are continuously copied, a copy having a high image density is usually obtained in the initial stage, but the charging of the toner gradually becomes non-uniform, and the density is reduced. Or a partial increase or decrease in the amount of toner on the developing sleeve tends to occur, making it difficult to obtain image blur and uniform image density.
[0027]
As described above, the addition of an external additive is generally used as a means for imparting a stable charging characteristic to a toner, but in any case, if any of them is missing, detached, transferred, etc., various problems may occur in the charging characteristic. And the final image quality is degraded. In particular, in order to realize a contact charging and cleaner-less system, it is particularly required that the external additives have high performance and high functionality.
[0028]
[Patent Document 1]
JP-A-50-13661
[Patent Document 2]
JP-A-5-61383
[Patent Document 3]
JP-A-3-145563
[Patent Document 4]
JP-A-4-3099961
[Patent Document 5]
JP-A-4-80764
[Patent Document 6]
JP-A-10-039534
[Patent Document 7]
JP 09-325517 A
[Patent Document 8]
JP-A-11-237763
[Patent Document 9]
JP-A-2-27664
[Patent Document 10]
JP-A-5-72797
[Patent Document 11]
JP-A-10-123822
[Patent Document 12]
JP-A-6-102699
[Patent Document 13]
JP-A-6-266156
[Patent Document 14]
JP-A-6-51561
[Patent Document 15]
JP-A-6-208242
[Patent Document 16]
JP-A-6-250442
[Non-patent document 1]
Transactions on Chemical Engineering (Vol. 18, No. 3, 303-307 (1992))
[0029]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner for use in an image forming method having an ozoneless contact charging and developing simultaneous cleaning step, which is environmentally friendly and has solved the above-mentioned problems. That is, a contact charging step in which the toner is prevented from sticking to the surface of the charging member to prevent poor charging and uneven charging due to filming of the toner on the member to be charged, and a high-resolution and high-definition image is obtained. After the process, the toner to be subjected to an image forming method having a developing process and a transfer process using a toner that hardly remains on the member to be charged and does not adhere to the surface of the charging member or the surface of the member to be charged is extremely small. The purpose is to provide.
[0030]
Further, an object of the present invention is to prevent the occurrence of scratches on the surface of the electrostatic image carrier, prevent the life of the electrostatic image carrier from being shortened, suppress the surface deterioration of the developer carrier even during long-term continuous development, and improve image quality. An object of the present invention is to provide a toner which is excellent in durability with less defects and image density, is less affected by the environment such as temperature and humidity, and has excellent charge stability and fluidity.
[0031]
It is a further object of the present invention to provide a toner which does not cause problems such as low developability and fog.
[0032]
Means and Action for Solving the Problems
The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. A charging process, (2) an exposure process for exposing a charged photoconductor to form an electrostatic latent image, (3) a developing process for developing the photoconductor with toner, and (4) a toner image via an intermediate transfer member. (5) an image forming method including a simultaneous developing and cleaning step of recovering toner remaining on the electrostatic latent image carrier after transfer to a developing unit in the developing step. The toner to be provided,
The toner has toner particles containing at least a colorant and a binder resin and an additive, and the external additive is a titanium compound obtained by subjecting metatitanic acid to a surface treatment with a silane compound or silicone oil. By using the characteristic toner, it has been found that a stable image without image quality density change, fog, filming can be obtained in a long-term continuous development without damaging the surface of the electrostatic image carrier, and the present invention It was completed.
[0033]
Furthermore, in the present invention, the metatitanic acid is formed of SiO₂Amount is 1 to 20% by mass, and the C reduction rate by toluene extraction is 25% or less.₂Hydrophobic metatitanic acid fine particles that have been surface-hydrophobized with an organic silane compound so that the amount reduction rate is 25% or less are excellent in charge stability over a long period of time, and no external additives are released from the toner. It has been found that the present invention is particularly effective in preventing damage to the photoreceptor due to agglomerates of free external additives, contamination of a charging member due to toner free of external additives, filming of the photoreceptor, and the like.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. The developer of the present invention comprises: (1) a charging step of applying a voltage from the outside to a charging member having a conductive rubber layer and a release film on the outside thereof to contact and charge a photoreceptor; An exposure step of exposing the body to form an electrostatic latent image, (3) a development step of developing the photoreceptor with toner, and (4) a transfer of the toner image to a transfer material with or without an intermediate transfer body. (5) Used as a developer in an image forming method having a simultaneous development and cleaning step in which toner remaining on the electrostatic latent image carrier after transfer is collected by a developing unit in the development step.
[0035]
The contact charging device applicable to the present invention is, for example, as shown in FIG. Reference numeral 2 denotes a charging member, 2a denotes a conductive support, 2c denotes a resistance control layer, and 2d denotes a surface layer. The charging roller may have a configuration of the elastic layer 2b without the resistance control layer 2c and the surface layer 2d.
[0036]
Metal such as iron, copper, stainless steel, aluminum and nickel can be used for the conductive support 2a used in the present invention. Further, these metal surfaces may be plated for the purpose of imparting rust prevention and scratch resistance, but it is necessary that the conductivity is not impaired.
[0037]
In the charging roller 2, the elastic layer 2b is provided with appropriate elasticity in order to ensure good uniform adhesion of the charging roller 2 to the photoconductor 1.
[0038]
The conductivity of the charging roller 2b is adjusted by adding conductive particles such as carbon black or conductive agents such as alkali metal salts and ammonium salts to an elastic material such as rubber. The elasticity is adjusted by adding a process oil and a plasticizer. Specific elastic materials of 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 (BR), synthetic rubbers such as nitrile-butadiene rubber (NBR) and chloroprene rubber (CR), and resins such as polyamide resin, polyurethane resin, silicone resin and fluorine resin. Further, a foam of the above-described elastic material may be used for the elastic layer 2b.
[0039]
The electric resistance of the elastic layer is 1 × 10³~ 1 × 10¹⁰It is preferable to have conductivity in the range of [Ωcm].
[0040]
The surface layer 2d is often provided to prevent bleed-out of the plasticizer and the like in the elastic layer 2b to the surface of the charging roller and to maintain the slipperiness and smoothness of the charging roller surface. The surface layer 2d is provided by coating or coating a tube.
[0041]
When the surface layer 2d is provided by coating, specific materials include resins such as polyamide resin, polyurethane resin, acrylic resin, fluororesin, and silicone resin, as well as epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber. Is mentioned. As a coating method, a dip coating method, a roll coating method, a spray coating method, or the like is preferable.
[0042]
When the surface layer 2d is provided by coating a tube, specific materials include nylon 12, PFA (ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin), PVDF (polyvinylidene fluoride), and FEP ( (Tetrafluoroethylene-hexafluoropropylene copolymer resin), and thermoplastic elastomers such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide.
[0043]
The tube may be a heat-shrinkable tube or a non-heat-shrinkable tube. In order to provide the surface layer 2d with appropriate conductivity, conductive particles such as carbon black and carbon graphite, and conductive metal oxides such as conductive titanium oxide, conductive zinc oxide, and conductive tin oxide are used. A conductive agent is used.
[0044]
The electric resistance of the surface layer is 1 × 10⁵~ 1 × 10¹⁴It is preferable to be within the range of [Ωcm].
[0045]
The resistance control layer 2c is often provided to control the resistance of the charging member. Specific examples of the material of the resistance control layer 2c include resins such as polyamide resin, polyurethane resin, fluorine resin, and silicone resin, and further include epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber. For the purpose of adjusting the resistance of the resistance control layer 2c as well, 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 are used. And a conductive agent such as an ammonium salt.
[0046]
The resistance control layer 2c is also provided by coating or coating a tube.
[0047]
The electric resistance of the resistance control layer is 1 × 10⁶~ 1 × 10¹⁰It is preferable to be within the range of [Ωcm].
[0048]
The measurement of the volume resistivity in the present invention is performed according to JIS @ K # 6911.
[0049]
As the photosensitive layer of the latent image holding member used in the present invention, known materials such as organic and amorphous silicon can be used. Further, the cylindrical holder for holding the photosensitive layer can be obtained by a known manufacturing method such as extruding aluminum or an aluminum alloy and processing the surface.
[0050]
As a developing method used in the present invention, a reversal developing method is preferably used. When the two-component magnetic brush developing method is used, magnetic ferrite particles, magnetite particles, iron powder, or those coated with a resin such as an acrylic resin, a silicone resin, or a fluororesin are used as the magnetic carrier. At this time, at the time of development or at the time of blank before and after the development, a bias of DC or AC component is applied to the developer carrier, and the potential is controlled so that the transfer residual toner on the photoconductor can be collected. At this time, the DC component is preferably set so as to be located between the light portion potential and the dark portion potential.
[0051]
As a one-component developer, a method is also used in which a toner is coated on the surface of an elastic roller serving as a developer carrier, and the toner is brought into contact with the surface of the photoreceptor. The toner may be either a magnetic toner or a non-magnetic toner. At this time, the cleaning is performed simultaneously with the development by the electric field between the photoreceptor and the elastic roller facing the photoreceptor surface via the toner. There is a need to have an electric field in a narrow gap with the surface. For this reason, the elastic rubber layer of the elastic roller is resistance-controlled in the medium resistance region to prevent conduction with the photoreceptor surface and maintain an electric field, or a method of providing a thin insulating layer on the surface layer of the conductive roller is used. it can. Further, a configuration in which a conductive layer is provided on a conductive roller on a conductive resin sleeve in which the outside in contact with the surface of the photoreceptor is coated with an insulating material, or an inside with an insulating sleeve not in contact with the surface of the photoreceptor.
[0052]
When the one-component contact developing method is used, the toner may be rotated in the same direction as the surface of the roller carrying the toner and the photoconductor, or may be rotated in the opposite direction. When the rotation is in the same direction, the peripheral speed ratio is preferably 100% or more (preferably 110% or more) with respect to the peripheral speed of the photoconductor. If it is less than 100%, the image quality tends to deteriorate. The higher the peripheral speed ratio, the greater the amount of toner supplied to the development site, the more frequently the toner is attached to and detached from the electrostatic latent image, and the unnecessary parts are scraped off and toner is applied to the necessary parts By repeating this operation, an image faithful to the electrostatic latent image is obtained. From the viewpoint of cleaning at the same time as the development, the effect that the transfer residual toner adhered to the photoreceptor is physically peeled off by the peripheral speed difference between the photoreceptor surface and the developer carrier and collected by an electric field can be expected. The higher the value, the more convenient the recovery of the transfer residual toner.
[0053]
In the transfer step, the toner image on the latent image holding member is transferred to a transfer member (for example, paper). Examples of the transfer unit in the present invention include a contact type in which a transfer roller is pressed against a latent image holding member and a non-contact type such as a non-contact type using a corotron. A contact type is generally used.
[0054]
As a specific example of the contact-type transfer step, a toner image is electrostatically transferred to a transfer material while a transfer unit is in contact with a photosensitive member, which is an electrostatic latent image carrier, via a transfer material. The contact pressure of the transfer unit is preferably a linear pressure of 2.94 N / m (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more.
[0055]
If the linear pressure as the contact pressure is less than 2.94 N / m, it is not preferable because transfer of the transfer material and transfer failure easily occur.
[0056]
As a transfer unit in the contact transfer step, an apparatus having a transfer roller or a transfer belt is used. The transfer roller has at least a core metal and a conductive elastic layer. The conductive elastic layer is made of polyurethane or EPDM rubber in which a conductive material such as carbon is dispersed.⁶-10¹⁰Ωcm.
[0057]
The developer used in the present invention includes toner particles containing at least a binder resin and a colorant, and an additive. The additive is a titanium compound obtained by subjecting metatitanic acid to a surface treatment with a silane compound or silicone oil.
[0058]
Further, the process of completing the hydrophobic metatitanate fine particles used in the developer of the present invention will be described.
[0059]
Drying metatitanic acid with the goal of monodisperse fine particles that have achieved hydrophobic treatment with uniform and excellent adhesion in order to complete the added fine particles that can impart stable charging performance and fluidity and do not release from the toner.・ A method of treating the organic silane compound in an aqueous system by pulverizing and dispersing the calcined powder was studied.In this method, especially when the particle diameter of metatitanic acid becomes small, drying of metatitanic acid is carried out. Strong coagulation occurred during firing. Therefore, although the degree of hydrophobicity was able to be increased, the specific surface area was small and the dispersibility was poor, which was not much different from the conventional ultrafine titanium oxide.
[0060]
Therefore, as a result of intensive studies to solve this problem, metatitanic acid was peptized with hydrochloric acid, an organic silane compound was added in a state of a non-agglomerated slurry, and coating treatment was performed, so Despite being certain metatitanic acid, the solid-liquid separated and dried powder has a high degree of hydrophobicity, has a high specific surface area, and has good dispersibility while maintaining non-aggregation even after drying. The particles were found to be fine particles, and the toner-added fine particles of the present invention, which are optimal for contact charging and a cleanerless system, were completed. Further, after the organic silane compound is added and stirred in an aqueous system, and then neutralized, washed, and dried, the reaction slurry is once alkalinized, and the mixture is kept under stirring to solidify the organic silane compound into metatitanic acid. The adhesion is improved, and as a result, continuous development is performed for a long period of time, and when stress is applied to the toner by the layer forming member or the like, the detachment of the hydrophobic metatitanate fine particles from the surface of the toner particles from the toner particles is suppressed. Further, the elimination of the organic silane compound from the surface of the hydrophobic metatitanic acid fine particles is suppressed, and the toner can maintain a desired hydrophobizing function, charge imparting ability, and the like for a long period of time. It has been found that a high-quality image free from fog, white spots, filming, and the like can be obtained without adhesion or damage, and the present invention has been completed.
[0061]
The method for producing metatitanic acid fine particles and hydrophobic metatitanic acid fine particles in the present invention will be described in more detail.
[0062]
It is particularly desirable that the metatitanate fine particles in the present invention be produced by a wet method. In the present invention, the method of treating the organic silane compound of the metatitanic acid fine particles is not particularly specified, and can be performed by a known method. A method in which a silane compound is hydrolyzed for treatment is effective, and is preferable in that a solvent is not used.
[0063]
In general, the production method of titanium oxide by a usual wet method is produced through a chemical reaction in a solvent, and can be divided into a sulfuric acid hydrolysis method and a hydrochloric acid hydrolysis method. When the sulfuric acid hydrolysis method is simplified, the following reaction proceeds in the liquid phase, and the insoluble TiO (OH)₂Is produced by hydrolysis.
FeTiO₃+ 2H₂SO₄→ FeSO₄+ TiOSO₄+ 2H₂O
TiOSO₄+ 2H₂O → TiO (OH)₂+ H₂SO₄
[0064]
In the hydrochloric acid hydrolysis method, titanium tetrachloride is produced by chlorination in the same manner as in the dry method. After that, it is dissolved in water, hydrolyzed while adding a strong base, and TiO (OH)₂Is produced. Briefly, it is as follows.
TiCl₄+ H₂O → TiOCl₂+2 HCl
TiOCl₂+ 2H₂O → TiO (OH)₂+2 HCl
[0065]
In a normal titanium oxide production process, washing and filtration are repeated thereafter, and the titanium oxide is obtained by firing. Further, if necessary, a treatment such as a silane compound is performed after pulverization and pulverization. However, the conventional production of this titanium oxide has a serious disadvantage that particles are sintered in the sintering step due to the strength of the bonding between Tis, and many agglomerations occur. Many solutions have been devised to solve this serious drawback, such as enhanced wet pulverization and treatment agent treatment before drying, but it has not been possible at present to disintegrate this agglomeration into primary particles. Even if this titanium oxide is applied to an additive of a toner, even if the coverage on the toner is combined with silica particles, fluidity comparable to that of silica cannot be obtained, and the phenomenon is thought to be caused by aggregation of the particles. As a result, photoreceptor flaws and filming occur. In addition, since the titanium oxide is agglomerated, the surface of the silane compound cannot be uniformly hydrophobized, and thus the charging ability, the charging speed, and the charging distribution of the toner are not at a satisfactory level. .
[0066]
In order to solve these problems, the metatitanic acid of the present invention undergoes peptization. There are several peptizing methods. For example, ammonia or caustic is added to the slurry of the agglomerated metatitanic acid, neutralized, filtered, washed with water to remove the remaining sulfate, and subsequently a strong basic monobasic acid such as hydrochloric acid, nitric acid, and trichloroacetic acid is added. In addition, there is a method of adjusting the pH to 3 or less, preferably 0.9 to 2.0. Also, a method of adding a salt that reacts with the sulfate group to form insoluble lead sulfate and at the same time forms a monobasic acid, such as barium chloride, in the slurry of the agglomerated metatitanic acid without performing the treatment of the desulfate group, etc. There is. The former method, in particular, the method of peptizing using hydrochloric acid, is more suitable for dissolving the organic silane compound and making the organic silane compound easy to react without mixing foreign substances.
[0067]
Next, a method of treating the surface of the metatitanate fine particles with an organic silane compound for hydrophobization of the present invention will be described. When an organic silane compound is added to the acidic slurry of metatitanic acid fine particles obtained by the peptizing method, the pH is adjusted to pH 3.0 or lower, preferably pH 2.0 or lower using an acid, if necessary. By setting the pH to the above value or more, the coating treatment of the organic silane compound can be uniformly promoted. Further, after stirring and holding, for the purpose of suppressing the self-condensation reaction of the organic silane compound and promoting the hydrolysis reaction more efficiently, once neutralizing the reaction slurry with an alkali before neutralization, the pH is preferably 7 to 13, preferably. Is 9-13, more preferably 9-11, and the temperature of the reaction slurry is heated to 20-100 ° C, preferably 30-70 ° C, and the mixture is kept under stirring. Thereafter, for the purpose of further promoting the hydrolysis reaction, if necessary, the pH is adjusted to 4 to 9, preferably 5 to 7, using an acid or alkali, and the temperature of the reaction slurry is adjusted to 20 to 100 ° C, preferably 30 to 70 ° C. Neutralize, wash, and dry at 100-190 ° C.
[0068]
The hydrophobic metatitanic acid fine particles in the present invention are prepared by reacting the metatitanic acid fine particles produced in the above-mentioned wet process with an organic silane compound under an acidic slurry without passing through a firing step of several hundred degrees, In order to promote a hydrolysis reaction between the reaction slurry and the organic silane compound, the reaction slurry is once stirred and maintained at pH 7 to 13 using an alkali, then neutralized, filtered, washed and dried. In this case, since the obtained hydrophobic metatitanic acid fine particles do not pass through a baking process of several hundred degrees, there is no strong bond between Tis, there is no aggregation, and the particles are almost primary particles in an organic silane compound and are hydrophobic. Can be processed. As a result, the conventional titanium oxide fine particles have high agglomeration properties, and required an excessive amount of an organic silane compound to obtain desired hydrophobicity and charge-imparting ability, whereas the production method of the present invention requires Since the cohesiveness of the metatitanic acid fine particles is low, the organic silane compound can be uniformly treated on the surface of the metatitanic acid fine particles, and an excessive amount of the organic silane compound is not required.
[0069]
Furthermore, in the production method of the present invention, after the metatitanic acid fine particles are reacted with the organic silane compound in an acidic slurry, the reaction slurry is once adjusted to pH 7 to 13 using an alkali and stirred and held. The rate of the self-condensation reaction is suppressed, and the rate of hydrolysis with the metatitanic acid fine particles can be accelerated. When the pH is higher than 13, it is possible to obtain the target fine particles of metatitanic acid, but this is not preferable in handling such as neutralization and washing. When the pH is less than 7, the ratio of the organic silane compound formed by self-condensation on the metatitanic acid surface and physically adsorbed increases, and the organic silane compound can efficiently perform a hydrolysis reaction on the metatitanic acid particles. Therefore, the ratio of the organic silane compound chemically adsorbed on the metatitanic acid surface decreases.
[0070]
That is, according to this method, the amount of the organic silane compound physically adsorbed on the surface of the metatitanic acid fine particles can be reduced and the amount of the silane compound chemically bonded can be increased. Strength increases. Further, by increasing the amount of the organic silane compound chemically bonded, the metatitanic acid fine particles can be efficiently coated and hydrophobically treated, and the amount of the organic silane compound to be treated can be reduced. As a result, when continuous development is performed for a long time and stress on the toner is known by the layer forming member or the like, detachment of the hydrophobic metatitanic acid fine particles from the surface of the toner particles can be suppressed. The elimination of the organic silane compound from the surface of the metatitanate fine particles is suppressed, and the desired hydrophobicity function, charge imparting ability, and the like of the toner can be maintained for a long period of time. It is possible to obtain a high-quality image without white spots or filming.
[0071]
Known alkalis can be used as the alkali used when the pH of the reaction slurry is adjusted to 7 to 13 or when neutralizing, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium carbonate. , Ammonia water, ammonia gas and the like can be used.
[0072]
As the acid used for the neutralization, known ones can be used, and for example, hydrochloric acid, nitric acid, carbonic acid, acetic acid, trichloroacetic acid and the like can be used.
[0073]
The drying temperature after washing with water is 100 to 190 ° C, preferably 110 to 170 ° C. If it is too low, the drying efficiency is poor and the degree of hydrophobicity is low. If it is too high, thermal decomposition of the hydrocarbon group occurs, causing discoloration and a decrease in the degree of hydrophobicity.
[0074]
The organic silane compound used in the present invention is not particularly limited as long as it is generally known, but it is used for the purpose of surface modification (for example, control of charging characteristics, and stability of charging under high humidity). ) And the reactivity of the organic silane compound. For example, organic silane compounds such as alkoxysilane, alkylalkoxysilane, siloxane, silane, and silicone oil can be used. The hydrophobizing treatment with the organic silane compound may be performed by using a hydrophobizing agent alone, or by using two or more hydrophobizing agents. For example, one kind of organic silane compound may be used for the hydrophobic treatment, or two kinds of organic silane compounds may be used simultaneously or after the hydrophobic treatment with the organic silane compound, another organic silane compound may be used. The compound may be further subjected to a hydrophobic treatment. Further, a generally known hydrophobizing agent such as a silane coupling agent, a titanate coupling agent, a silicone oil, or a silicone varnish may be used in combination.
[0075]
Particularly preferred is an alkoxysilane having both a volatile group, a hydrophobic group, and a highly reactive bonding group, such as a coupling agent.
[0076]
Specifically, for example, as a silane coupling agent, a general formula
RmSiYn
R: alkoxy group
m: an integer from 1 to 3
Y: alkyl group, vinyl group, phenyl group, methacryl group, amino group, epoxy group, mercapto group or derivatives thereof
n: an integer from 1 to 3
Are preferable, for example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane Examples thereof include silane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-otatadecyltrimethoxysilane.
[0077]
Particularly preferred in the present invention is the general formula
C_nH_{2n + 1}-Si- (OC_mH_{2m + 1})₃
n = 4-12
m: 1-3
And a coupling agent represented by Here, if n in the general formula is smaller than 4, the treatment becomes easy, but the degree of hydrophobicity cannot be sufficiently achieved. On the other hand, if n is larger than 12, hydrophobicity is sufficient, but coalescence between titanium oxides is increased, and the ability to impart fluidity is reduced. On the other hand, if m is larger than 3, the reactivity will be reduced and the hydrophobicization will not be sufficiently performed.
[0078]
Therefore, in the present invention, n is 4 to 12, preferably 4 to 8, and m is 1 to 3, preferably 1 to 2.
[0079]
Examples of the silicone oil used in the present invention include dimethyl silicone oil, alkyl-modified silicone oil, α-methyl sulfone-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.
[0080]
The treatment amount of the organic silane compound with respect to the metatitanic acid fine particles is the same as that of the hydrophobic metatitanic acid fine particles.₂Amount is 1 to 20% by mass, and the C reduction rate by toluene extraction is 25% or less,₂It is sufficient if the processing amount is such that the reduction rate of the amount is 25% or less (C amount, SiO amount₂The method of measuring the amount and the method of extraction with toluene will be described later).
[0081]
SiO₂Amount is more than 20% by mass, or the C reduction rate by toluene extraction is more than 25%,₂When the amount reduction rate is greater than 25%, the organic silane compound physically adsorbed on the metatitanic acid surface increases, and continuous development is performed for a long time, and stress is applied to the toner by a charging member such as a carrier. At the time, the organic silane compound is detached from the surface of the hydrophobic metatitanate fine particles, and the toner cannot maintain the desired hydrophobizing function and charging ability for a long period of time, or the detached organic silane compound becomes an electrostatic image. Since the toner adheres to or damages the surface of the carrier, fog, white spots, filming, and the like occur, and a high-quality image cannot be obtained. In addition, the surplus organic silane compound is turned into oil and causes a problem in fluidity of the toner.
[0082]
The hydrophobic metatitanic acid fine particles SiO₂If the amount is less than 1% by mass, the desired degree of hydrophobicity cannot be obtained.
[0083]
In the present invention, the hydrophobicity of the hydrophobic metatitanic acid fine particles surface-treated with the organic silane compound is in the range of 40 to 90%, and preferably 50 to 80%.
[0084]
When the degree of hydrophobicity is less than 40%, the triboelectric charge of the toner is liable to decrease, particularly in a high humidity environment, the toner scatter, fog and image quality are liable to occur. On the other hand, if the degree of hydrophobicity is larger than 90%, it is difficult to control the charging of the hydrophobic metatitanate fine particles themselves, and the toner tends to be charged up particularly in a low humidity environment.
[0085]
The number average particle diameter of the hydrophobized metatitanic acid fine particles is preferably from 10 to 100 nm from the viewpoints of imparting fluidity to the toner and polishing.
[0086]
When the number average particle size is smaller than 10 nm, the toner particles are easily embedded in the surface of the toner particles, so that the toner is likely to deteriorate at an early stage, the durability is reduced, and the inorganic fine particles surface-treated with a hydrophobizing agent and a charge control agent are used. Low abrasiveness.
[0087]
When the number average particle size is larger than 100 nm, the toner tends to be less likely to be charged because the fluidity of the toner is reduced, and as a result, image quality is deteriorated, toner is scattered, and fogging is apt to occur. Further, the surface of the photoreceptor is easily damaged, and image defects such as a noticeable roughness of a halftone image are likely to occur.
[0088]
The BET specific surface area of the hydrophobic metatitanic acid fine particles is 50 to 350 m.²/ G is preferred.
[0089]
BET specific surface area of hydrophobic metatitanate fine particles is 50m²If the particle size is smaller than / g, it indicates that the hydrophobic metatitanic acid fine particles have a large particle size and that metatitanic acid aggregates or coarse particles are present, and that the image quality is deteriorated due to a decrease in the fluidity of the toner or damage to the photoreceptor surface. Problems, such as a decrease in the number, are likely to occur. Further, the particle size of the hydrophobic metatitanic acid fine particles is easily released from the toner particles, and a large amount of the liberated hydrophobic metatitanic acid fine particles remains in the developing machine or adheres to various devices in the image forming apparatus main body, which has an adverse effect. It is not preferable because it affects.
[0090]
BET specific surface area of hydrophobic metatitanic acid fine particles is 350 m²If it is larger than / g, the amount of water adsorbed on the hydrophobic metatitanic acid fine particles increases, which may adversely affect the charging characteristics of the toner. In particular, the amount of triboelectric charge of the toner decreases in a high humidity environment, and toner scattering, fogging, and image quality deterioration are likely to occur.
[0091]
The hydrophobic metatitanic acid fine particles are externally added and mixed as an external additive in an amount of 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the toner. The hydrophobic metatitanic acid fine particles may be used alone or in combination of two or more, or a plurality of other external additives may be used in combination.
[0092]
Other external additives according to the present invention include silica, strontium titanate, barium titanate, cerium oxide, cerium fluoride, aluminum oxide, titanium oxide, magnesium fluoride, silicon carbide, boron carbide and titanium carbide as in the prior art. Organic particles such as zirconium carbide, magnetite, molybdenum disulfide, aluminum stearate, magnesium stearate, zinc stearate, tin oxide, and various inorganic fine particles, polytetrafluoroethylene, polyvinylidene fluoride, polymethyl methacrylate, polystyrene, and silicone. Fine particles may be used alone or in combination. By externally adding the above-mentioned fine powder to the toner particles, the fine powder exists between the toner and the carrier or between the toner particles, whereby the fluidity of the developer is improved, and the life of the developer is further improved. Also improve. However, in the present invention, external addition of these fine particles to the toner particles is not essential. The average particle diameter of the fine powder described above is preferably 0.2 μm or less. When the average particle diameter exceeds 0.2 μm, the effect of improving the fluidity is reduced, and the image quality may be deteriorated due to a defect at the time of development or transfer. The measurement of the average particle size of these fine powders will be described later.
[0093]
The specific surface area of these fine powders is 30 m by nitrogen adsorption by the BET method.²/ G or more, especially 5 to 400 m²/ G is good. The addition amount of the fine powder is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the toner.
[0094]
Further, the inorganic fine particles are preferably subjected to a hydrophobic treatment in order to maintain the chargeability under high humidity. The hydrophobizing agent is not particularly limited as long as it is a generally known treating agent, but the organic silane compounds exemplified in the surface treatment of the inorganic fine particles of the present invention can be used. The treatment amount is preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass, based on 100 parts by mass of the inorganic fine particles.
[0095]
Next, the toner used in the present invention will be described.
[0096]
Further, as the toner shape, if the ratio of the minor axis length / major axis length exceeds 0.8, the toner particles relatively easily move on the photoreceptor due to rubbing of the magnetic particles. More preferably, it exceeds 0.90.
[0097]
As the binder resin used in the toner of the present invention, a wide variety of resins known as binder resins for toner such as styrene resins, polyester resins, acrylic resins, phenol resins, and epoxy resins can be used alone or in combination of two or more. It is.
[0098]
Conventionally known inorganic and organic dyes and pigments can also be used as the colorant, for example, carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodun lake, alizarin lake, bengala, phthalocyanine Blue and indanthrene blue. These are usually used in an amount of 0.5 to 20 parts by mass based on 100 parts by mass of the binder resin.
[0099]
For the purpose of controlling the charge, a nigrosine dye, a quaternary ammonium salt, a salicylic acid-based metal complex or metal salt, an azo compound, acetylacetone, or the like can be used.
[0100]
In order to prepare the toner particles according to the present invention, for example, a binder resin, a wax, a metal salt or a metal complex, a pigment as a colorant, a dye, or a magnetic substance, a charge control agent as needed, and other additives After thoroughly mixing with a mixer such as a Henschel mixer or a ball mill, a heating roll, a kneader, a metal compound in which the resins are melt-kneaded using a hot kneader such as an extruder to mutually dissolve the resins, Pigments, dyes, and magnetic substances are dispersed or dissolved, and after cooling and solidifying, pulverization and classification are performed to obtain toner particles according to the present invention.
[0101]
The shape of the toner particles depends on the pulverizing and classifying step, and usually, the average circularity measured by a flow type particle image measuring device is 0.950 to 0.995, and the circularity standard deviation is less than 0.040. Is more preferable.
[0102]
When the average circularity is within the range, the round shape of the toner reduces the load such as pressure and rubbing on the toner. When the average circularity is within the range, the transfer residual toner passes through the contact band member with a lighter load, so that the fusion of the toner member is less likely to occur. At the same time, it means that the difference in physical properties between the recovered transfer residual toner and the fresh toner is reduced, thereby enhancing the function of maintaining the developability and transferability. Further, when the circularity standard deviation is less than 0.040, it means that the shape distribution of the toner is narrow, so that the toner fusion to the member, deterioration, developability or transferability are also improved.
[0103]
In order to obtain a shape having an average circularity exceeding 0.950, it is preferable to control the shape by mechanically and thermally treating the surface. As a method for controlling the shape, a known method can be used. For example, a hybridization system manufactured by Nara Machinery Co., Ltd., Angmill manufactured by Hosokawa Micron Corporation, or the like can be used. Further, a method of forming into a sphere by hot air, a method of forming into a sphere in a warm bath, a method of dissolving in a solvent and forming into a sphere by a spray drying method are also possible.
[0104]
As toner particles having an average circularity exceeding 0.950, it is preferable to use toner particles produced by a polymerization method. In particular, since the toner particles in which the surface layer portion of the toner particles is formed by a polymerization method are generated by polymerizing the monomer composition in a dispersion medium, the surface of the toner particles can be obtained with a considerably smoothed surface. .
[0105]
A method of directly producing toner particles from a polymerizable monomer composition using a suspension polymerization method described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842. Alternatively, the polymerizable monomer is soluble in a polymer obtained by dissolving the obtained polymer directly in an aqueous organic solvent using a dispersion polymerization method or a polymerizable monomer in the presence of a water-soluble polar polymerization initiator. It is possible to produce toner particles using an emulsion polymerization method such as a soap-free polymerization method in which toner particles are directly polymerized to form toner particles.
[0106]
When a direct polymerization method is used as a method for producing toner particles, examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile. Azo or diazo polymerization such as 1,1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile Initiator: A peroxide-based polymerization initiator such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide is used. The amount of the polymerization initiator varies depending on the desired degree of polymerization, but is generally used in an amount of 0.5 to 20% by mass based on the polymerizable monomer. The type of the polymerization initiator varies slightly depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.
[0107]
In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like may be further added and used.
[0108]
When a suspension polymerization is used for producing a toner, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, and water are used as an inorganic oxide as a dispersant. Examples include calcium oxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salts of carboxymethylcellulose, starch and the like. It is preferable to use 0.2 to 10.0 parts by mass of these dispersants based on 100 parts by mass of the polymerizable monomer.
[0109]
As these dispersants, commercially available ones may be used as they are, but in order to obtain dispersed particles having a fine uniform particle size, fine particles of the inorganic compound are generated under high-speed stirring in a dispersion medium such as water. Is also good. For example, in the case of tricalcium phosphate, under high-speed stirring, by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution to produce tricalcium phosphate fine particles, a fine-grained dispersant suitable for suspension polymerization can be obtained. Can be.
[0110]
In order to refine these dispersants, a surfactant of 0.001 to 0.1 parts by mass may be used in combination. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. Examples include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, and the like.
[0111]
When a direct polymerization method is used to produce toner particles, toner particles can be produced by the following production method.
[0112]
A mold release agent, a colorant, a charge control agent, a polymerization initiator and other additives made of a low softening point substance were added to the polymerizable monomer, and the resulting mixture was uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser or the like. The monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer using a conventional stirrer or a high-shear stirrer such as a homomixer or a homogenizer. Preferably, the granulation is performed by adjusting the stirring speed and the stirring time so that the droplets of the monomer composition have a desired size of the toner particles. After that, stirring may be performed by the action of the dispersion stabilizer to such an extent that the particle state is maintained and settling of the particles is prevented. The polymerization is preferably performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and further in the latter half of the reaction or in order to remove unreacted polymerizable monomers and by-products for the purpose of improving durability in the image forming method of the present invention. After completion, a part of the aqueous medium may be distilled off from the reaction system.
[0113]
After the reaction is completed, the generated toner particles are collected by washing, filtration, and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer composition.
[0114]
As the carrier used when the toner of the present invention is used as a two-component developer, for example, surface-oxidized or unoxidized iron, nickel, copper, zinc, cobalt, manganese, chromium, metals such as rare earths and alloys thereof or Oxides and ferrites or their resin dispersed carriers can be used. In addition, there is no particular limitation on the manufacturing method.
[0115]
Further, the surface of the carrier may be covered with a resin or the like as necessary. As the method, any conventionally known method such as a method of dissolving or suspending a coating material such as a resin in a solvent, coating and adhering to a carrier, and a method of simply mixing with a powder can be applied.
[0116]
The fixing substance on the carrier surface varies depending on the toner material, for example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of ditertiary butyl salicylic acid, styrene resin, Acrylic resin, polyamide, polyvinyl butyral, nigrosine, aminoacrylate resin, basic dyes and lakes thereof, silica fine particles, alumina fine particles, and the like are suitable for use alone or in combination, but are not necessarily limited thereto.
[0117]
The amount of the compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but is generally preferably 0.1 to 30% by mass (preferably 0.5 to 20% by mass) based on the carrier.
[0118]
These carriers preferably have an average particle size of 10 to 100 μm, preferably 20 to 70 μm.
[0119]
When a two-component developer is prepared by mixing with the toner of the present invention, the mixing ratio is preferably 2 to 15% by mass, and more preferably 4 to 13% by mass, as the toner concentration in the developer. Can be If the toner density is less than 2%, the image density is low and cannot be used practically. If the toner density is more than 15%, fog and scattering inside the machine are increased, and the useful life of the developer is shortened.
[0120]
Although the developing method of the present invention is not particularly limited, a system in which the developing unit is also a substantial cleaning unit, that is, the electrostatic charge after transfer between the transfer position and the charging position and between the charging position and the developing position In the case of a so-called cleaner-less system having no cleaning means for collecting and storing the toner remaining on the image carrier, reversal development is preferable, and a structure in which the developer and the electrostatic image carrier come into contact with each other. Is preferred. For example, a contact two-component developing method, a contact one-component developing method, and the like are mentioned as suitable developing methods. This is because, when the developer and the transfer residual toner are in contact with each other at the time of leaving the electrostatic image, the rubbing force is applied electrostatically, and the transfer residual toner tends to be effectively collected by the developing unit. It is preferable that the DC component of the bias applied during the development be between the black portion (the exposed portion in the case of reversal development) and the potential of the white background portion.
[0121]
In the present invention, the transfer residual toner is transported from the charging means (charging device) from which the toner is temporarily recovered to the developing portion by using the surface of the electrostatic image carrier to be collected and reused. There is no need to change the body charging bias. However, practically, when a transfer material jam occurs or when images having a high image ratio are continuously obtained, the amount of the transfer toner mixed into the charger may be extremely large. In this case, during operation of the electrophotographic apparatus, the toner may be moved from the charger to the developing device by utilizing the time when an image is not formed on the electrostatic image carrier. The non-image forming time includes the time of pre-rotation, the time of post-rotation, and between transfer materials. In this case, it is also preferable to change the charging bias so that the toner is more easily transferred to the electrostatic image carrier than the charger. As a method of facilitating discharge from the charger, the peak-to-peak voltage of the AC component is reduced, or only the DC component is used. Further, there is a method of changing the waveform to lower the AC effective value without changing the peak-to-peak voltage.
[0122]
In the present invention, if the above-mentioned hydrophobic inorganic fine particles are used, transferability and fog are improved, and application to a cleanerless system becomes easy. In particular, carrier contamination under high humidity is suppressed, a long life is achieved with a small amount of developer, and it is suitable for miniaturization of the apparatus. In the present invention, the diameter of the developer carrier is 20 mm or less, preferably Those having a size of 16 mm or less can be suitably used. The electrostatic image carrier having a diameter of 40 mm or less, preferably 30 mm or less, and more preferably 24 mm or less can be suitably used.
[0123]
An image forming method to which the present invention can be applied will be described below with reference to the accompanying drawings.
[0124]
FIG. 2 is a diagram showing an image forming apparatus to which the present invention is applied. The image forming apparatus includes image forming units 31Y, 31M, 31C, and 31BK for forming a toner image on a photosensitive drum serving as an image carrier, an intermediate transfer belt 4a for transferring the toner image in a single transfer, and an image on the belt 4a. The secondary transfer roller 40 is a transfer unit that transfers the toner image of the recording medium 2 to the recording medium 2, a sheet feeding unit that sends the recording medium 2 between the intermediate transfer belt 4a and the secondary transfer roller 40, and the recording medium 2 is transported to the transfer unit. The apparatus includes a feeding unit, a fixing unit, and a paper discharging unit.
[0125]
Hereinafter, the image formation will be described.
[0126]
As shown in FIG. 2, a paper cassette 3a for stacking and storing a plurality of recording media (for example, recording paper, OHP sheets, cloth, etc.) 2 is detachably mounted on the image forming apparatus. The recording medium 2 fed from the paper feed cassette 3a by the pickup roller 3b is separated one by one by a pair of retard rollers 3c, and is conveyed to a pair of registration rollers 3g by conveyance rollers 3d and 3f.
[0127]
When the recording medium 2 is conveyed, the registration roller pair 3g stops rotating, and the recording medium 2 is skewed by being hit against the nip.
[0128]
In the case of a four-drum full-color system, four process cartridges of yellow, magenta, cyan, and black are arranged in parallel in the process cartridges BY, BM, BC, and BB including the image carrier, as shown in FIG. An optical scanning system 1Y, 1M, 1C, 1BK is provided for each of the process cartridges BY, BM, BC, BB, and a toner image is formed on a photosensitive drum for each color by an image signal, and then transferred. The toners of the respective colors are superimposedly transferred onto the intermediate transfer belt 4a running in the direction of the arrow by the rollers 4Y, 4M, 4C, and 4BK.
[0129]
Thereafter, the recording medium 2 is sent to the secondary transfer roller 40 at a predetermined timing, the toner image on the intermediate transfer belt 4a is transferred onto the recording medium 2, and is fixed by the fixing device 5, and then the discharge roller pair. 3h and 3i, and are stacked on the tray 6 on the apparatus body 14.
[0130]
The image forming units 31Y, 31M, 31C, and 31BK constitute process cartridges BY, BM, BC, and BB, respectively, except for the optical scanning systems 1Y, 1M, 1C, and 1BK. Since the configuration of the process cartridge is the same, only the process cartridge BY will be described.
[0131]
As shown in FIG. 3, the process cartridge BY is provided with a charging unit, an exposure unit, a developing unit, and a transfer opening around the photosensitive drum 7. In this embodiment, a two-component developer having a magnetic carrier powder is used. Therefore, as the photoconductor drum 7 used in the embodiment of the present invention, a commonly used organic photoconductor can be used.
[0132]
The charging unit is a charging roller 8 having conductivity. The charging roller 8 is driven by the rotation of the photosensitive drum.
[0133]
In this embodiment, the developing means employs a method in which a two-component developer is brought into a contact state and developed.
FIG. 3 shows the developing means 10 for two-component magnetic brush development used in the present embodiment. The developing sleeve 10d has a hollow cylindrical shape and is rotatably supported. A fixed magnet 10c is provided in the developing sleeve 10d. The developing sleeve 10d rotates in the same direction as the photosensitive drum 7, and the peripheral surface moves in a direction opposite to the moving direction of the peripheral surface of the photosensitive drum 7. The photoconductor drum 7 and the developing sleeve 10d are not in contact with each other and have a gap of about 0.2 to 1.0 mm, and are set so that the developer can be developed while being in contact with the photoconductor drum 7. .
[0134]
The toner mixed with the carrier is supplied by stirring screws 10g and 10h in a casing partitioned by a longitudinal partition wall 10f excluding both ends. The toner supplied from a toner supply container (not shown) drops to one end of the stirring screw 10g, is stirred while being sent in one longitudinal direction, passes through the portion without the partition 10f at the other end, and is stirred by the stirring screw 10h. It moves to one end side, and then is stirred and circulated while being fed by the stirring screw 10g through the part without the partition wall 10f on one end side.
[0135]
Here, a developing process of visualizing the electrostatic latent image formed on the photosensitive drum 7 by the two-component magnetic brush method using the developing device 10 and a developer circulation system will be described.
[0136]
First, the developer pumped up by the poles of the magnet 10c with the rotation of the developing sleeve 10d is regulated by a regulating blade 10e arranged perpendicular to the developing sleeve 10d in the process of being conveyed, and is placed on the developing sleeve 10d. A thin layer is formed. When the developer having a thin layer formed thereon is conveyed to the main developing pole, ears are formed by magnetic force. The electrostatic latent image on the photosensitive drum 7 is developed with the spike-shaped developer, and the developer on the developing sleeve 10d is returned to the developing container 10a by the repulsive magnetic field.
[0137]
A DC voltage and an AC voltage are applied to the developing sleeve 10d from a power supply (not shown). In general, in the two-component development method, when an AC voltage is applied, the development efficiency is increased, and the quality of an image is high. On the contrary, fogging is liable to occur. For this reason, usually, by providing a potential difference between the DC voltage applied to the developing sleeve 10d and the surface potential of the photosensitive drum 7, toner is prevented from adhering to the non-image area during development.
[0138]
This toner image is then transferred to an intermediate transfer belt 4a, which is an intermediate transfer body, by the intermediate transfer device 4 in FIG. The intermediate transfer device 4 winds an endless belt 4a around a drive roller 4b, a driven roller 4c, and a secondary transfer opposing roller 4d, and is rotated in the direction of the arrow in FIG. Further, transfer rollers 4Y, 4M, 4C, and 4BK are provided in the transfer belt 4a, and each transfer roller generates a pressing force from the inside of the belt 4a toward the photosensitive drum 7 (7Y, 7M, 7C, BK). The toner image on the photosensitive drum 7 is sequentially transferred to the upper surface of the intermediate transfer belt 4a by being charged from the back side of the belt 4a by being supplied with power from the high voltage power supply, thereby performing charging of the opposite polarity to the toner.
[0139]
A belt made of a polyimide resin can be used as the intermediate transfer belt 4a. The material of the belt 4a is not limited to polyimide resin, but may be a dielectric such as polycarbonate resin, polyethylene terephthalate resin, polyvinylidene fluoride resin, polyethylene naphthalate resin, polyetheretherketone resin, polyethersulfone resin, or polyurethane. Plastic such as resin, or fluorine-based or silicon-based rubber can be suitably used.
[0140]
Transfer residual toner remains on the surface of the photosensitive drum 7 after the transfer of the toner image. The transfer residual toner passes through the charging roller, is captured by the magnetic brush of the developing unit, and is collected by the developing device.
[0141]
FIG. 5 is a schematic view of a process cartridge of a contact one-component developing system which can be used in the present invention. The cartridge 40 contains a toner 42 and includes a toner carrier 4 that rotates in the direction of the arrow in contact with the photoconductor 1. The photoconductor 1 is charged by the contact charging unit 2. Further, a developing blade 43 for regulating the amount of toner and applying a charge, a toner 42 is attached to the toner carrier 4, and an application roller 41 which rotates in the direction of the arrow to apply a charge to the toner by friction with the toner carrier 4. It also has.
[0142]
Hereinafter, specific examples of the measurement method used in the present invention will be described.
[0143]
(Method of measuring C content)
The amount of C in the sample was quantified using an elemental analyzer for metals (EMIA-110, manufactured by Horiba, Ltd.). (Can also be measured with an organic element measuring device)
[0144]
(SiO₂How to measure the amount)
SiO in the sample₂The amount was quantified using an X-ray fluorescence analyzer (RIX3000 manufactured by Rigaku Corporation).
[0145]
(C content and SiO₂(The rate of decrease in the amount of toluene extracted)
15 g of the sample and 100 g of special grade toluene were put in a 500 ml plastic bottle container, shaken at 25 ° C. and 150 rpm × 1 hour with a shaker (YS-LDII manufactured by Yayoi Co., Ltd.), then centrifuged and dried under reduced pressure. Samples before and after toluene extraction were analyzed for C content and SiO₂The amount was measured, and the amount of C by extraction and SiO₂The rate of decrease in volume was calculated.
[0146]
(Measurement of toner particle size)
The particle size distribution can be measured by various methods, but in the present invention, the measurement was performed using a Coulter counter.
[0147]
As a measuring device, a Coulter Counter TA-II type (manufactured by Coulter) was used, and an interface (manufactured by Nikkaki) for outputting the number average distribution and volume distribution and a PC9801 personal computer (manufactured by NEC) were connected. A 1% NaCl aqueous solution is prepared using graded sodium chloride. As a measuring method, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume of the colorant-containing resin particles or toner particles was measured using the Coulter Counter TA-II using an aperture of 100 μm. The number is measured to calculate a volume distribution of 2 to 40 μm and a number distribution. Then, the mass-based mass average diameter (D4) obtained from the volume distribution according to the present invention (the median value of each channel is set as a representative value for each channel), and the mass-based coarse powder amount (16.0 μm) obtained from the volume distribution Above), the number-based fine powder number (5.04 μm or less) obtained from the number distribution is obtained.
[0148]
(Measurement of average circularity of toner)
The average circularity of the toner and the standard deviation of the circularity 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-1000 (Toa Medical Electronics Co., Ltd.) (Manufactured by the company).
[0149]
As a specific measuring method, 10 ml of ion-exchanged water from which impurity solids and the like have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measured. Add 0.02 g of sample and disperse uniformly. As a dispersing means, an ultrasonic dispersing machine UH-50 type (manufactured by SMT Co., Ltd.) equipped with a titanium alloy chip of 5φ as a vibrator is used for a dispersion treatment for 5 minutes to obtain a dispersion for measurement. At this time, the dispersion is appropriately cooled so that the temperature of the dispersion does not exceed 40 ° C.
[0150]
To measure the shape of the toner particles, the flow particle image measuring device was used, and the dispersion concentration was readjusted so that the concentration of the toner particles at the time of measurement was 3000 to 10,000 particles / μl. Measure above. After the measurement, using this data, the average circularity and the standard deviation of the circularity of the toner particles were calculated using the following equation.
[0151]
(Equation 1)

[0152]
(Equation 2)

[0153]
Here, the “particle projection area” is the area of the binarized toner particle image, and the “perimeter of the particle projection image” is the length of the contour obtained by connecting the edge points of the toner particle image. Define.
[0154]
The circularity in the present invention is an index indicating the degree of unevenness of the toner particles. When the toner particles are perfectly spherical, the circularity is 1.000. The more complicated the surface shape, the smaller the circularity.
[0155]
In the present invention, the circle-equivalent number average diameter D1 (μm) and the particle diameter standard deviation SDd, which mean the average value of the number-based particle diameter frequency distribution, are the particle diameter (center value) at the dividing point i of the particle diameter distribution. Where di is the frequency and fi is the frequency.
[0156]
(Equation 3)

[0157]
(Equation 4)

[0158]
The average circularity C and the circularity standard deviation SDc which mean the circularity frequency distribution mean the circularity (center value) at the dividing point i of the particle size distribution and the frequency f, respectively._ciThen, it is calculated from the following equation.
[0159]
(Equation 5)

[0160]
(Measurement of hydrophobicity)
The methanol titration test is an experimental test for confirming the degree of hydrophobicity of the hydrophobic inorganic fine particles. 0.2 g of hydrophobic inorganic fine particles are added to 50 ml of water in a 250 ml Erlenmeyer flask. Methanol is titrated from Hewlett until the entire amount of hydrophobic inorganic fine particles is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed when the entire amount of the hydrophobic inorganic fine particles is suspended in the liquid, and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.
[0161]
(Method of measuring BET specific surface area)
The BET of the hydrophobic inorganic fine particles is measured in the following manner.
[0162]
The BET specific surface area is determined by a BET multipoint method using a fully automatic gas adsorption measuring device: Autosorb 1, manufactured by Yuasa Ionics Co., Ltd., using nitrogen gas as the adsorbed gas. In addition, as pretreatment of a sample, deaeration is performed at a temperature of 50 ° C. for 10 hours.
[0163]
(Measurement method of average particle size of hydrophobic inorganic fine particles)
The primary particle diameter is obtained by observing the hydrophobic inorganic fine particles with a transmission electron microscope, measuring the particle diameter of 100 particles in the visual field, and calculating the average particle diameter.
[0164]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. “Parts” means “parts by mass”.
[0165]
Production example of hydrophobic metatitanic acid A
A 6N aqueous sodium hydroxide solution was added to the metatitanic acid slurry having a number average primary particle diameter of 40 nm obtained by the sulfuric acid hydrolysis method while stirring, and the mixture was maintained at pH 8.5 with stirring for 1 hour. The mixture was filtered, and washed with water. Water was added to the washed cake to form a slurry again, and 12N hydrochloric acid was added with stirring to adjust the pH to 1 / l. The mixture was then stirred for 2 hours and peptized. 100 g of metatitanic acid was collected from the deflocculated slurry, and 50 g (50% by mass) of isobutyltrimethoxysilane was added while heating and maintaining the temperature at 40 ° C. with stirring, and the mixture was stirred and maintained for 30 minutes. Next, the pH of the reaction slurry was once adjusted to 9.8 (40 ° C.) by adding an 8N aqueous sodium hydroxide solution, and the mixture was stirred for 10 minutes, neutralized with 8N hydrochloric acid to pH 6.6 (40 ° C.), filtered, and washed with water. Was done.
[0166]
After the washed cake is dried at 130 ° C., it is finely pulverized by a fine pulverizer using an air jet method,₂11% by mass, C reduction rate by toluene extraction 12%, SiO₂Amount reduction rate 12%, hydrophobicity 57%, BET specific surface area 120m²/ G of the desired hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid A).
[0167]
Production example of hydrophobic metatitanate B
A 6N sodium hydroxide aqueous solution was added to a metatitanic acid slurry having a number average primary particle size of 30 nm obtained by a sulfuric acid hydrolysis method while stirring to adjust the pH to 9.3, and the mixture was stirred and maintained for 1 hour, and then neutralized to pH 5.5 with 12N hydrochloric acid. Then, filtration and washing with water were performed. Water was added to the washed cake to form a slurry again, and 12N hydrochloric acid was added thereto with stirring to adjust the pH to 1.2, and the mixture was stirred and maintained for 2 hours to perform a peptization treatment. From this peptized slurry, 100 g of metatitanic acid was fractionated, 10 g (10% by mass) of isobutyltrimethoxysilane was added while heating and maintaining the temperature at 40 ° C., and the mixture was stirred and maintained for 30 minutes. Next, an aqueous 8N sodium hydroxide solution was added to the reaction slurry to adjust the pH to 9.6 (40 ° C.), and the mixture was stirred and maintained for 10 minutes, neutralized to pH 6.5 (40 ° C.) with 8N hydrochloric acid, filtered, and washed with water. Was done.
[0168]
After the washed cake is dried at 130 ° C., it is finely pulverized by a fine pulverizer using an air jet method,₂5% by mass, 10% reduction of C by toluene extraction, SiO₂Amount reduction rate 10%, hydrophobicity 35%, BET specific surface area 130m²/ G of the desired hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid B).
[0169]
Production example of hydrophobic metatitanic acid C
Except that the amount of isobutyltrimethoxysilane added was changed to 90 g (90% by mass), SiO₂18% by mass, 17% reduction of C by toluene extraction, SiO₂Amount reduction rate 14%, hydrophobicity 95%, BET specific surface area 140m²/ G of hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid C).
[0170]
Production example of hydrophobic metatitanic acid D
An external additive was used, except that the metatitanic acid slurry obtained by the sulfuric acid hydrolysis method had a number average primary particle diameter of 120 nm by pH adjustment and the amount of isobutyltrimethoxysilane added was changed to 40 g (40% by mass). SiO in the same manner as A₂8% by mass, C reduction rate by toluene extraction 12%, SiO₂Amount reduction rate 12%, hydrophobicity 55%, BET specific surface area 30m²/ G of hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid D).
[0171]
Production example of hydrophobic metatitanic acid E
In the production example of hydrophobic metatitanic acid A, the addition amount of isobutyltrimethoxysilane was changed to 70 g (70% by mass), and after stirring and holding for 30 minutes, an 8N aqueous sodium hydroxide solution was added, and the mixture was directly allowed to reach pH 6.5 (40 ° C). Except for neutralization, use the same method₂13% by mass, 20% reduction of C by toluene extraction, SiO₂Volume reduction rate 17%, hydrophobicity 60%, BET specific surface area 130m²/ G of hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid E).
[0172]
Production example of hydrophobic metatitanate F
In the production example of the hydrophobic metatitanic acid A, the same method was used except that polydimethylsiloxane emulsion was used as an active ingredient in place of isobutyltrimethoxysilane and the amount was changed to 20 g (20% by mass).₂15% by mass, 22% reduction of C by toluene extraction, SiO₂Volume reduction rate 17%, hydrophobicity 55%, BET specific surface area 70m²/ G of hydrophobic metatitanic acid fine particles (hydrophobic metatitanic acid F).
[0173]
Production example of hydrophilic titanium oxide G
Untreated hydrophilic anatase-type titanium oxide G was obtained in the same manner as in the production example of metatitanic acid A except that isobutyltrimethoxysilane was not used.
[0174]
(Production Example 1 of Toner Particle)
・ Styrene 100 parts
・ Methyl methacrylate 10 parts
・ N-butyl acrylate 10 parts
・ C. I. Pigment Yellow 74 8 parts
・ Al-ditert-butylsalicylate compound 1.5 parts
・ Saturated polyester (terephthalic acid-propylene oxide modified bisphenol
A, acid value 14 mgKOH / g, peak molecular weight 8500) 10 parts
・ Ester wax (behenyl behenate) 40 parts
The above formulation was heated to 60 ° C. and uniformly dissolved and dispersed at 10,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). Into this, 5 parts of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
[0175]
Separately, 0.1M-Na₃PO₄450 parts of the aqueous solution was charged and heated to 60 ° C., and then stirred at 1,300 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). 1.0M-CaCl₂68 parts of an aqueous solution is gradually added, and Ca₃(PO₄)₂Was obtained.
[0176]
The polymerizable monomer composition was charged into the aqueous medium, and 2 parts of polyethylene was further added.₂Under an atmosphere, the mixture was stirred at 12,000 rpm for 10 minutes with a Clea mixer to granulate the polymerizable monomer composition. Thereafter, the temperature was raised at 80 ° C. while stirring the aqueous medium with a paddle stirring blade, and a polymerization reaction was performed for 8 hours.
[0177]
After completion of the polymerization reaction, the mixture was cooled, hydrochloric acid was added to melt calcium phosphate, and then filtered, washed with water and dried to obtain polymerized particles (toner particles 1). The weight average particle diameter of the obtained polymerized toner particles A was 6.7 μm, the average circularity was 0.980, and the circularity standard deviation was 0.032.
[0178]
The obtained toner particles 1 were confirmed to have a core-shell structure in which wax was encapsulated in an outer resin layer by a tomography method of polymerized particles using a transmission electron microscope (TEM).
[0179]
(Method 2 for producing toner particles)
C. I. Magenta polymer particles (toner particles 2) were obtained in the same manner as in the production example of toner particles 1 except that quinacridone pigment was used instead of Pigment Yellow 74. The obtained toner particles 2 had a weight average particle diameter of 6.7 μm, an average circularity of 0.979 and a standard deviation of 0.034.
[0180]
(Production Example 3 of Toner Particle)
C. I. Pigment Yellow 74 instead of C.I. I. Pigment Blue 15: 3 was used, and cyan polymer particles (toner particles 3) were obtained in the same manner as in the production example of toner particles 1. The obtained toner particles 3 had a weight average particle size of 6.7 μm, an average circularity of 0.981, and a circularity standard deviation of 0.029.
[0181]
(Production Example 4 of Toner Particle)
C. I. Polymer particles of black color (toner particles 4) were obtained in the same manner as in the production example of toner particles 1, except that carbon black was used instead of Pigment Yellow 74. The obtained toner particles 4 had a weight average particle size of 6.8 μm, an average circularity of 0.980, and a circularity standard deviation of 0.031.
[0182]
<Example 1>
To 100 parts of the black particles obtained in Production Example 4 of the toner particles, 1.2 parts of hydrophobic metatitanic acid A was added, and the mixture was stirred at 3000 rpm in a Henschel mixer 10B (manufactured by Mitsui Miike Kakoki Co., Ltd.). Mixing was performed for 3 minutes to obtain a black toner.
[0183]
8 parts of the above toner and 92 parts of a magnetic fine particle-dispersed resin carrier obtained by dispersing magnetite particles in a phenol resin are mixed to form a two-component developer. As an image forming apparatus, a commercially available digital copying machine GP55 (manufactured by Canon) Was modified so that the developing device of FIG. 3 could be inserted. Specifically, a SUS sleeve having a diameter of 16 mm adjusted to have a surface roughness Rz of 12.5 μm by sandblasting was used as the developer carrying member. As the charging member, the charging device shown in FIG. 1 is used, and is rotated at 100% in the forward direction with respect to the contact portion of the photoreceptor to apply a DC / AC electric field (-600 V, 1.5 kHz / 1.2 kVpp). It was superimposed and charged. The developing contrast was set to -200 V, the back contrast was set to -200 V, a developing bias having an AC voltage shown in FIG. 4 was applied from a bias applying means (not shown), and the surface layer of both the fixing roller and the pressure roller was PFA 1.2 μm. Changed to a coated roller and modified to remove the oil application mechanism. Using an original document with an image area of 5%, 15 ° C / 10% (L / L), 30 ° C / 80% (H / H) A 10,000-sheet paper-passing test was performed in each environment, and the evaluation was performed based on the following evaluation methods. The results are shown in Table 1. As can be seen from the table, good results were obtained.
[0184]
(Image density)
Using a Macbeth densitometer RD918 type (Macbeth Densitometer RD918manufactured by Macbeth Co.) manufactured by Macbeth and fitted with an SPI filter, five solid patches of 20φ (original original density 1.5) were formed on plain paper. The average image density was measured.
[0185]
(Fog)
The average reflectance Dr (%) of plain paper before image formation was measured by a reflectometer (“REFRECTOMETER MODEL TC-6DS” manufactured by Tokyo Denshoku Co., Ltd.). On the other hand, a solid white image was formed on plain paper, and the reflectance Ds (%) of the solid white image was measured. Fog (%) is the following formula
Fog (%) = Dr (%)-Ds (%)
Calculated from
[0186]
(Halftone image uniformity)
A halftone image having a Macbeth image density of 0.3 to 0.6 is output, and the uniformity of density, the feeling of roughness, and the degree of image defects are visually evaluated.
A: A good output image with excellent image density uniformity.
：: Although the uniformity of the image density is slightly lacking, it is a level at which there is no practical problem.
Δ: The image has poor uniformity in image density and is a rough output image, which is a practically problematic level.
X: The image density was extremely poor in uniformity, and streaks or spot-like image defects due to contamination of the charging roller were conspicuous, making it impractical.
[0187]
<Example 2>
An image was evaluated in the same manner as in Example 1, except that the hydrophobic metatitanic acid A was hydrophobic metatitanic acid B. The results are shown in Table 1. As can be seen from the table, good results were obtained although the durability was slightly inferior. This is presumed to be due to the fact that the surface treatment was slightly non-uniform and the charge stabilizing effect on the toner was slightly impaired, as can be seen from the low hydrophobicity.
[0188]
<Example 3>
An image was evaluated in the same manner as in Example 1, except that the hydrophobic metatitanic acid A was hydrophobic metatitanic acid C. The results are shown in Table 1. As can be seen from the table, all the evaluation items were slightly inferior to those of Examples 1 and 2, but this was because the degree of hydrophobicity was large and the charging speed of the toner was reversed. Probably because of the decline.
[0189]
<Example 4>
The image was evaluated in the same manner as in Example 1 except that the hydrophobic metatitanic acid A was hydrophobic metatitanic acid D. The results are shown in Table 1. As can be seen from the table, all the evaluation items were slightly inferior, but it is presumed that the fluidity of the toner was slightly lowered due to the large particle diameter.
[0190]
<Example 5>
The image was evaluated in the same manner as in Example 1 except that the hydrophobic metatitanic acid A was hydrophobic metatitanic acid E. The results are shown in Table 1. As can be seen from the table, the durability was slightly inferior in all the evaluation items. However, this is because the amount of extraction was slightly large, so that when the stress due to the durability was applied, the hydrophobic metatitanic acid fine particles were used. It is considered that a large amount of the residue was released from the surface, so that the toner could not maintain a suitable chargeability, and spent on a carrier and contaminated various parts of the developing device.
[0191]
<Example 6>
The image was evaluated in the same manner as in Example 1 except that the hydrophobic metatitanic acid A was hydrophobic metatitanic acid F. The results are shown in Table 1. As can be seen from the table, good results were obtained in all the items, though slightly inferior. This is considered to be due to the fact that the treatment of titanium oxide is made of silicone oil, so that it tends to aggregate, and the fluidity of the developer is slightly inferior.
[0192]
<Example 7>
Each of the yellow, magenta, cyan, and black toner particles obtained in Toner Production Example 1, Toner Production Example 2, Toner Production Example 3, and Toner Production Example 4 was externally added under the same conditions as in Example 1. Then, toner of each color was obtained.
[0193]
To 8 parts of the toner, 92 parts of a magnetic material-dispersed resin carrier prepared in the carrier production example were mixed to prepare a developer, and 250 g of the developer was used for each color in the developing device shown in FIG. To form a four-color process toner cartridge.
[0194]
FIG. 2 shows the above-described cartridges in each environment of 15 ° C./10% (L / L) and 30 ° C./80% (H / H) based on the same evaluation method as in Example 1. Using a full-color image forming apparatus, a printing speed of 23 sheets / minute in A4 width was used, and a continuous print test of 10,000 sheets was performed using an original document having a print ratio of 5% of the paper area. Evaluation results are shown in Table 1. As can be seen from the table, good results were obtained in all items.
[0195]
<Comparative Example 1>
The image was evaluated in the same manner as in Example 1 except that the hydrophobic metatitanic acid A was hydrophilic titanium oxide G. The results are shown in Table 1. As can be seen from the table, all the evaluation items deteriorated. The reason for this is that, since no hydrophobic treatment has been performed, the charge imparting property due to moisture adsorption is remarkably inferior, and the adhesion to the carrier, the charging roller and the photoreceptor is high. It is presumed that the defect became remarkable.
[0196]
<Comparative Example 2>
An image was evaluated in the same manner as in Example 1 except that T805 (manufactured by Degussa), which was synthesized from titanium tetrachloride by a gas phase method instead of hydrophobic metatitanic acid A and then treated with a silane coupling agent, was used. The results are shown in Table 1. As can be seen from the table, a defective image due to fog and contamination of the charging roller occurred in the latter half of the endurance. It is presumed that the deterioration of the fog is due to the fact that the treating agent is weaker in chemical bonding property than metatitanic acid because it is an acid value titanium produced by a gas phase method, and the charging property of the toner is deteriorated by the peeling of the treating agent in the latter half of the durability. It is presumed that the contamination of the charging roller was caused by the presence of the sintered lumps in the titanium oxide accumulated on the charging roller with the endurance.
[0197]
[Table 1]

[0198]
【The invention's effect】
According to the present invention, even in an environment-friendly system in which an ozone-less contact charging and simultaneous cleaning step of developing are introduced, problems of charging member contamination and photoreceptor scratches do not occur, and a stable and good image without fog can be obtained for a long period of time. Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a contact charging device.
FIG. 2 is a schematic explanatory view showing an example of a full-color image forming method.
FIG. 3 is a schematic view illustrating a preferred example of a developing device of the present invention.
FIG. 4 is a schematic diagram illustrating an AC electric field used in an example.
FIG. 5 is a process cartridge of a contact one-component developing system which can be used in the present invention.
[Explanation of symbols]
1 photoreceptor
2) Charging member

Claims (6)

(1) a charging step in which a voltage is applied from the outside to a charging member having a conductive rubber layer and a release film on the outside thereof to perform contact charging on the photoconductor; and (2) an electrostatic charge by exposing the charged photoconductor. An exposure process for forming a latent image, (3) a development process for developing the photoreceptor with toner, (4) a transfer process for transferring a toner image to a transfer material with or without an intermediate transfer member, (5) A toner for use in an image forming method having a simultaneous development and cleaning step of collecting toner remaining on an electrostatic latent image carrier after transfer to a developing unit in the development step,
The toner has toner particles containing at least a colorant and a binder resin and an additive, and the external additive is a titanium compound obtained by subjecting metatitanic acid to a surface treatment with a silane compound or silicone oil. Characterized toner. The toner according to claim 1, wherein the external additive is a titanium compound obtained by a reaction between metatitanic acid and a silane compound. The surface of the metatitanic acid is hydrophobized with an organic silane compound such that the amount of SiO ₂ is 1 to 20% by mass, the rate of C reduction by toluene extraction is 25% or less, and the rate of SiO ₂ reduction is 25% or less. The toner according to claim 1, which is a treated hydrophobic metatitanate fine particle. The toner according to any one of claims 1 to 3 BET specific surface area of the hydrophobic metatitanic acid particles is characterized by a 50~350m ² / g. The toner according to any one of claims 1 to 4, wherein the number average particle diameter of the hydrophobic metatitanic acid fine particles is 10 to 100 nm. 6. The toner according to claim 1, wherein the hydrophobic metatitanic acid fine particles have a degree of hydrophobicity of 40 to 90%.

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