JP3589262B2 - Polymerized toner - Google Patents

Description

（式中、Ｒ^１は、炭素原子数１〜８のアルキル基、Ｒ^２及びＲ^３は、それぞれ独立に炭素原子数１〜１８のアルキル基、Ｒ^４は、炭素原子数１〜８のアルキル基またはベンジル基である。）
で表される４級アンモニウム塩０．０１〜０．４重量部とを含有し、かつ、４級アンモニウム塩／ニグロシン系染料の重量比が０．０１〜５．０の範囲内であることを特徴とする非磁性一成分現像方式に用いられる重合トナーが提供される。
【００１４】
【発明の実施の形態】
本発明の重合トナーは、少なくとも重合性単量体、着色剤、及び帯電制御剤を含有する組成物を、分散安定剤を含有する水系分散媒体中に投入し、攪拌して液滴粒子を造粒し、次いで、昇温して懸濁重合することにより製造することができる。重合開始剤としては、油溶性の重合開始剤を用い、通常、重合性単量体組成物中に添加する。
【００１５】
重合性単量体
本発明で使用する重合性単量体としては、ビニル基を有する単量体が好ましく使用される。重合性単量体の具体例としては、例えば、スチレン、α−メチルスチレン、ｐ−メチルスチレン、ｐ−クロロスチレン、ビニルトルエン等の芳香族ビニル単量体類；アクリロニトリル、メタクリロニトリル等の不飽和ニトリル類；メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、ラウリル（メタ）アクリレート、ステアリル（メタ）アクリレート等の不飽和（メタ）アクリル酸エステル類；アクリル酸、メタクリル酸などのアクリル酸類；エチレン、プロピレン、ブチレン、イソブチレン等のエチレン性不飽和モノオレフィン類；塩化ビニル、塩化ビニリデン、臭化ビニル、フッ化ビニル等のハロゲン化ビニル類；酢酸ビニル、プロピオン酸ビニル等のビニルエステル類；ビニルメチルエーテル、ビニルエチルエーテル等のビニルエーテル類；ビニルメチルケトン、メチルイソプロオペニルケトン等のビニルケトン類；２−ビニルピリジン、４−ビニルピリジン、Ｎ−ビニルピロリドン等の含窒素ビニル化合物；ブタジエン、イソプレン等の共役ジオレフィン類；等を挙げることができる。これらの重合性単量体は、それぞれ単独で、あるいは２種以上を組み合わせて使用することができる。
これらの単量体の中でも、スチレンなどの芳香族ビニル単量体及び／または不飽和（メタ）アクリル酸エステル類が、疎水性が高いため好ましい。スチレン−アクリレート共重合体が特に好ましい。重合性単量体の疎水性が高いと、極性の高いニグロシン系染料及び４級アンモニウム塩は、トナーの表面に集まるため、使用量が従来の粉砕法トナーより少量となる。すなわち、従来の粉砕法トナーと比較すると、ニグロシン染料の使用割合を１／１０以下に、４級アンモニウム塩の使用割合を１／２〜１／１０程度の少量としても、十分に満足できる帯電性を有する重合トナーを得ることができる。
【００１６】
着色剤
本発明で使用する着色剤としては、例えば、カーボンブラック、ニグロシンベース、アニリンブルー、カルコオイルブルー、クロムイエロー、ウルトラマリンブルー、オリエントオイルレッド、フタロシアニンブルー、マラカイトグリーンオクサレート、ローダミンＢ、クリスタルバイオレット等の顔料及び染料を挙げることができる。染顔料は、重合性単量体１００重量部に対して、通常、０．１〜２０重量部、好ましくは１〜１０重量部の割合で用いられる。
また、着色剤として、酸化チタン、二酸化ケイ素、酸化亜鉛等の金属酸化物；鉄、コバルト、ニッケル、三二酸化鉄、四三酸化鉄、酸化鉄マンガン、酸化鉄亜鉛、酸化鉄ニッケル等の磁性粒子；なども適量の範囲で使用することができる。これらの金属酸化物や磁性粉を着色剤として使用する場合には、１μｍ以下の微粒子を用いることが好ましい。
【００１７】
油溶性重合開始剤
油溶性重合開始剤としては、使用する単量体に可溶なものであればよく、例えば、メチルエチルパーオキシド、ジ−ｔ−ブチルパーオキシド、アセチルパーオキシド、ジクミルパーオキシド、ラウロイルパーオキシド、ベンゾイルパーオキシド、ｔ−ブチルパーオキシ−２−エチルヘキサノエート、ジ−イソプロピルパーオキシジカーボネート、ジ−ｔ−ブチルジパーオキシイソフタレート等の過酸化物類；２，２′−アゾビス（２，４−ジメチルバレロニトリル）、２，２′−アゾビスイソブチロニトリル、１，１′−アズビス（１−シクロヘキサンカルボニトリル）等のアゾ化合物；などを挙げることができる。油溶性重合開始剤は、重合性単量体１００重量部に対して、通常、０．１〜２０重量部、好ましくは１〜１０重量部の割合で用いられる。重合開始剤は、重合性単量体組成物中に予め添加することができるが、場合によっては、造粒工程終了後の懸濁液に添加することもできる。
【００１８】
各種添加剤
重合性単量体組成物には、分子量調整剤、架橋性単量体、離型剤などを添加することができる。
分子量調整剤としては、例えば、ｔ−ドデシルメルカプタン、ｎ−ドデシルメルカプタン、ｎ−オクチルメルカプタン等のメルカプタン類；四塩化炭素、四臭化炭素等のハロゲン化炭化水素類；などを挙げることができる。これらの分子量調整剤は、重合開始前、あるいは、重合の途中で添加することができる。分子量調整剤は、重合性単量体１００重量部に対して、通常、０．０１〜１０重量部、好ましくは０．１〜５重量部の割合で用いられる。
架橋性単量体としては、例えば、ジビニルベンゼン、エチレングリコールジ（メタ）アクリレート、グリシジル（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート等の多官能性単量体類を挙げることができる。これらの架橋性単量体は、重合開始前、あるいは、重合の途中で添加することができる。架橋性単量体は、重合性単量体１００重量部に対して、通常、０．０１〜１０重量部、好ましくは０．５〜５重量部の割合で用いられる。
離型剤としては、例えば、低分子量ポリエチレン、低分子量ポリプロピレン、低分子量ポリブチレン等の低分子量ポリオレフィン類を挙げることができる。離型剤は、重合性単量体１００重量部に対して、通常、０．１〜２０重量部、好ましくは１〜１０重量部の割合で用いられる。
着色剤のトナー粒子中への均一分散化を目的として、オレイン酸、ステアリン酸等の滑剤；シラン系またはチタン系カップリング剤等の分散助剤；などを重合性単量体組成物中に存在させてもよい。このような滑剤や分散助剤は、着色剤の重量を基準として、通常、１／１０００〜１／５０程度の割合で用いられる。
【００１９】
帯電制御剤
本発明では、帯電制御剤として、ニグロシン系染料と前記式（Ｉ）で表される４級アンモニウム塩を使用する。
ニグロシン染料としては、公知のものが使用可能であり、例えば、オリエント化学（株）製のボントロン Ｎシリーズ（Ｎ−０１、Ｎ−０２、Ｎ−０３、Ｎ−０４、Ｎ−０５、Ｎ−０７、Ｎ−０９、Ｎ−１０、Ｎ−１１、Ｎ−１３、Ｎ−ＥＸ）、オリエント スピリットブラックＡＢ、オリエント スピリットブラックＳＢ、ソルベントブラック＃５、ソルベントブラック＃７；住友化学（株）製のスピリットブラックＮｏ．８５０、スピリットブラックＮｏ．９００などを挙げることができる。
式（Ｉ）で表される４級アンモニウム塩の具体例としては、下記の式（１）〜（１０）の化合物を挙げることができる。
【００２０】
【化３】

【００２１】
【化４】

【００２２】
【化５】

【００２３】
【化６】

【００２４】
【化７】

【００２５】
【化８】

【００２６】
【化９】

【００２７】
【化１０】

【００２８】
【化１１】

【００２９】
【化１２】

【００３０】
このような４級アンモニウム塩としては、例えば、オリエント化学（株）製のＰ−５１、Ｐ−５３などのＰシリーズを使用することができる。
本発明では、重合性単量体１００重量部に対して、ニグロシン系染料０．０１〜１．０重量部及び式（Ｉ）で表される４級アンモニウム塩０．０１〜０．４重量部を、４級アンモニウム塩／ニグロシン系染料の重量比０．０１〜５．０の範囲内で使用する。これにより得られる重合トナーは、正に帯電する。
正帯電トナーの帯電制御剤にニグロシン系染料のみを使用すると、初期の印字品質は満足できるが、印字枚数が増えると帯電量が低下し、感光体上のカブリが増える。また、４級アンモニウム塩のみを使用すると、連続印字での帯電量の変化は少ないが、トナーの帯電量が低く、満足できる印字品質が得られない。この両者を併用することにより、初期の印字品質に優れ、連続印字での画質の安定性を得ることができる。
【００３１】
重合性単量体１００重量部に対するニグロシン系染料の割合が１．０重量部を超過すると、感光体上のカブリが大きく、画像濃度も低下し、０．０１重量部未満になると、十分な帯電量を得ることができない。
重合性単量体１００重量部に対する４級アンモニウム塩の割合が０．４重量部を超過すると、トナーの帯電量が低くなり、感光体上のカブリが大きく、画像濃度も低くなり、０．０１重量部未満になると、印字枚数が増えると帯電量が低下し、感光体上のカブリが増え、画像濃度も低くなる。４級アンモニウム塩の割合は、好ましくは０．０２〜０．３重量部である。
また、４級アンモニウム塩／ニグロシン系染料の重量比は、０．０１〜５．０の範囲内にすることが必要である。この重量比が５．０を超過すると、トナーの帯電量が不十分となり、感光体上のカブリが増え、画像濃度も低下し、０．０１未満になると、感光体上のカブリが大きく、画像濃度も低下する。この重量比は、好ましくは０．０５〜４．０である。
【００３２】
本発明では、このように、限定された小割合でニグロシン系染料と４級アンモニウム塩を使用する点に特徴がある。特に、重合単量体として、例えば、スチレンやアクリレートなどの疎水性の高い単量体を使用すると、極性の高いニグロシン及び４級アンモニウム塩がトナーの表面に集まるため、使用量が従来の粉砕法トナーより少量となる。前記した通り、本発明の重合トナーは、従来の粉砕法トナーと比較すると、ニグロシン系染料は１／１０以下で、４級アンモニウム塩も１／２〜１／１０程度の少量で十分な帯電性と連続印字での画質の安定性を達成することができる。
【００３３】
また、４級アンモニウム塩は、重合性単量体に難溶性であるため、生成する重合トナーよりも小粒径に粉砕されていることが好ましい。より具体的には、重合トナー中に含まれる４級アンモニウム塩の体積平均粒径を５μｍ以下とすることにより、４級アンモニウム塩を重合トナーの各粒子に平均に分散させることができる。ニグロシン系染料も重合性単量体に難溶性であるため、生成する重合トナーよりも小粒径に粉砕されていることが好ましい。粗大な帯電制御剤を用いて重合トナーを製造すると、個々の重合トナー粒子への帯電制御剤の分散が不均一になり、その結果、重合トナーの帯電量分布がブロードとなって、カブリなどの不都合が生じやすい。そこで、これらの帯電制御剤は、体積平均粒径５μｍ以下に粉砕分級して使用することが好ましい。ただし、原料作成の段階で、体積平均粒径が５μｍ以下のものを調製して使用することもできる。体積平均粒径は、コールターカウンター（コールター社製）により測定した体積平均粒径（ｄｖ）である。
【００３４】
懸濁重合法
重合性単量体組成物は、分散安定剤を含有する水系分散媒体中に投入し、攪拌して液滴粒子を造粒し、次いで、昇温して懸濁重合する。
本発明では、水系分散媒体として、水または水を主成分とする水性液体を用いることができる。分散安定剤としては、例えば、ポリビニルアルコール、メチルセルロース、ゼラチン等の水溶性高分子類；リン酸カルシウム、硫酸バリウム、硫酸カルシウム、炭酸バリウム、炭酸カルシウム、炭酸マグネシウム等の難水溶性塩類；珪酸等の無機高分子物質；酸化アルミニウム、酸化チタン等の金属酸化物；水酸化アルミニウム、水酸化マグネシウム、水酸化第二鉄等の金属水酸化物；等を挙げることができる。分散安定剤は、それぞれ単独で、あるいは２種以上を組み合わせて用いることができる。分散安定剤は、水系分散媒体１００重量部に対して、通常、０．１〜２０重量部、好ましくは０．５〜１８重量部の割合で用いられる。
【００３５】
本発明において、重合性単量体組成物と水系分散媒体との割合は、特に限定されないが、分散媒体中での造粒のし易さや重合反応中での粒子の分散安定性を考慮すると、系中の重合性単量体組成物の濃度が、通常、５〜５０重量％、好ましくは１０〜４０重量％、より好ましくは２０〜３５重量％程度となる範囲が好ましい。
造粒工程の後、造粒された重合性単量体組成物は、常法により懸濁重合して重合トナーを形成する。懸濁重合反応終了後、通常行う酸洗い、及び水洗により粒子表面に残留している分散安定剤を除去し、しかる後、脱水、乾燥することにより重合トナーを得ることができる。重合トナーの体積平均粒径は、通常、１〜５０μｍ、好ましくは５〜３０μｍ、より好ましくは２〜２０μｍである。重合トナーには、コロイダルシリカなどの流動化剤を外添することができる。
【００３６】
【実施例】
以下に実施例及び比較例を挙げて、本発明についてより具体的に説明する。
なお、以下の実施例及び比較例において、「部」は、重量部を表す。
物性の測定法は、下記の通りである。
（１）帯電量の測定
吸引式帯電量測定装置を用い、現像ロール上のトナーを吸引し、単位質量当たりの帯電量を測定した値である。
（２）感光体カブリの測定
感光体ドラム上のカブリの部分のトナーをメンディングテープで紙に転写し、白色度計で測定した反射率の値を、メンディングテープだけを紙に貼った時の反射率を白色度計で測定した値から引いた値である。
（３）画像濃度の測定
画像濃度の評価はマクベス反射濃度計を用い、「黒べた部」を測定することにより行った。
【００３７】
［実施例１］
スチレン ７０部
ｎ−ブチルアクリレート ３０部
カーボンブラック ７部
（モナーク１２０、キャボット社製）
帯電制御剤
▲１▼ニグロシン系染料 ０．０１部
（Ｎ−０５、オリエント化学社製）
▲２▼４級アンモニウム塩 ０．０２部
（Ｐ−５３、オリエント化学社製）
ジビニルベンゼン ０．３部
２，２′−アゾビスイソブチロニトリル ２部
ポリプロピレン ２部
（ビスコール５５０Ｐ、三洋化成社製）
ただし、ニグロシン系染料のＮ−０５は、予めジェットミルで粉砕した後、分級し、体積平均粒径２．８μｍとしたものを用いた。また、４級アンモニウム塩Ｐ−５３は、予めジェットミルで粉砕した後、分級し、体積平均粒径３．０μｍとしたものを用いた。
【００３８】
上記各成分を高剪断力を有する混合機であるＴＫ式ホモミキサー（特殊機化工社製）により撹拌、混合して、均一分散した重合性単量体組成物を調製した。一方、リン酸カルシウム３部を蒸留水２５０部中に添加し、該リン酸カルシウムが微細に分散した分散液を得た。このリン酸カルシウム分散液に上記の重合性単量体組成物を添加し、ＴＫ式ホモミキサーにより高剪断撹拌を行い、重合性単量体組成物の液滴を造粒した。この造粒した重合性単量体組成物の水分散液を撹拌翼を装置した反応器に入れ、６５℃で８時間、撹拌下に重合を行った。このようにして得られた重合体の分散液を、酸洗、水洗を十分に行った後、分離、乾燥し、着色粒子たるトナー材料を得た。得られた着色粒子の粒径をコールターカウンター（コールター社製）により測定したところ、体積平均粒径が９．０μｍであった。
上記により得られた重合トナー１００部に、疎水化処理したコロイダルシリカ（商品名：ＨＶＫ２１５０、ヘキスト社製）０．５部を添加し、ヘンシェルミキサーを用いて混合し、現像剤を得た。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において良好な画質が得られ、初期の帯電量は１８μＣ／ｇであった。続いて２万枚の連続印字を行ったところ、画像濃度及び感光体カブリに変化が見られず、良好な画質が得られた。この時の帯電量は、１６μＣ／ｇであり、ほとんど変化が見られなかった。
【００３９】
［実施例２］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において良好な画質が得られ、初期の帯電量は２７μＣ／ｇであった。続いて２万枚の連続印字を行ったところ、画像濃度及び感光体カブリに変化が見られず、良好な画質が得られた。この時の帯電量は、２３μＣ／ｇであり、ほとんど変化が見られなかった。
【００４０】
［実施例３］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において良好な画質が得られ、初期の帯電量は２０μＣ／ｇであった。続いて２万枚の連続印字を行ったところ、画像濃度及び感光体カブリに変化が見られず、良好な画質が得られた。この時の帯電量は、１８μＣ／ｇであり、ほとんど変化が見られなかった。
【００４１】
［実施例４］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において良好な画質が得られ、初期の帯電量は３２μＣ／ｇであった。続いて２万枚の連続印字を行ったところ、画像濃度及び感光体カブリに変化が見られず、良好な画質が得られた。この時の帯電量は、２５μＣ／ｇであり、ほとんど変化が見られなかった。
【００４２】
［比較例１］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。この例では、帯電制御剤としてニグロシン系染料のみを用い、４級アンモニウム塩は使用しなかった。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において良好な画質が得られ、初期の帯電量は２５μＣ／ｇであった。続いて２万枚の連続印字を行ったところ、画像濃度の低下及び感光体カブリの増加が見られた。この時の帯電量は、５μＣ／ｇであり、帯電量の低下が確認された。
【００４３】
［比較例２］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。この例では、帯電制御剤として４級アンモニウム塩のみを用い、ニグロシン系染料は用いなかった。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において画像濃度が低く、画像もかすれており、不十分であった。この時の帯電量は５μＣ／ｇであった。
【００４４】
［比較例３］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。この例では、４級アンモニウム塩／ニグロシン系染料の重量比が１０と大きいものであった。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において画像濃度が低く、画像もかすれており、不十分であった。この時の帯電量は５μＣ／ｇであった。
【００４５】
［比較例４］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。この例では、ニグロシン系染料の使用割合が２．０重量部と大きいものであった。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において感光体カブリの増加がみられた。この時の初期の帯電量は５０μＣ／ｇであった。
【００４６】
［比較例５］
帯電制御剤の使用割合を表１に示すように変更したこと以外は、実施例１と同様にして、非磁性一成分現像剤を得た。この例では、４級アンモニウム塩の使用割合が１．０重量部と大きいものであった。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において画像濃度が低く、画像もかすれており、不十分であった。この時の帯電量は５μＣ／ｇであった。
【００４７】
［比較例６］
スチレン／ｎ−ブチルアクリレート／ジビニルベンゼン
（重量比８５／１５／０．３）共重合体 １００部
カーボンブラック ７部
（モナーク１２０、キャボット社製）
帯電制御剤
▲１▼ニグロシン系染料 ０．３部
（Ｎ−０５、オリエント化学社製）
▲２▼４級アンモニウム塩 ０．２部
（Ｐ−５３、オリエント化学社製）
ポリプロピレン ２部
（ビスコール５５０Ｐ 三洋化成社製）
上記の成分を配合、混練、粉砕し、分級して体積平均粒径９．１μｍの黒色のトナーを得た。このようにして得られたトナー粒子１００部に疎水化処理したコロイダルシリカ（商品名ＨＶＫ２１５０、ヘキスト社製）０．５部を添加し、ヘンシェルミキサーを用いて混合し、現像剤を得た。
上記により得られた現像剤を非磁性一成分接触現像方式の正帯電プリンターで印字評価したところ、初期において画像濃度が低く、画像もかすれており、不十分であった。この時の帯電量は５μＣ／ｇであった。
【００４８】
【表１】

【００４９】
【発明の効果】
本発明によれば、懸濁重合法により得られる重合トナーであって、安定した帯電性を有し、初期の印字品質が良好で、かつ、連続印字での画質の安定性に優れた重合トナーが提供される。本発明の重合トナーは、優れた流動性と安定した帯電性を有しており、特に、非磁性一成分現像剤として好適である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner for developing an electrostatic image used in electrophotography, electrostatic recording, electrostatic printing, and the like, and more specifically, a polymerized toner obtained by a suspension polymerization method, having a stable chargeability. And a polymerized toner having good initial printing quality and excellent image quality stability in continuous printing.
[0002]
[Prior art]
Conventionally, in an electrophotographic apparatus, an electrostatic recording apparatus, or the like, an electric or magnetic latent image is visualized by toner. For example, in electrophotography, an electrostatic charge image (latent image) is formed on a photoreceptor, and then the latent image is developed using toner to form a toner image. The toner image is usually transferred onto a transfer material such as paper, and then fixed by a method such as heating. The toner used for electrostatic image development is generally a colored particle containing a colorant, a charge control agent, and other additives in a binder resin.The production method is roughly classified into a pulverization method and a pulverization method. There is a suspension polymerization method. Further, as the electrostatic image developer, a two-component developer composed of a toner and carrier particles and a one-component developer composed substantially of only a toner are known. The one-component developer includes a magnetic one-component developer in which a magnetic powder is contained in a toner and a non-magnetic one-component developer without a magnetic powder.
[0003]
In the two-component developing method, electric charge is applied to the toner by frictional charging between the toner and carrier particles, and the electrostatic latent image is visualized by the toner. However, the two-component developing method requires a large amount of carrier particles in addition to the toner, so there is a limit to miniaturization, and a control mechanism for controlling the ratio of the toner and the carrier particles to a predetermined ratio is required. Will be higher.
The magnetic one-component developing method uses a magnetic one-component developer in which a magnetic powder is contained in a toner and does not require carrier particles, so that the size can be reduced. However, since the magnetic one-component developer contains a large amount of magnetic powder having a small electric resistance, it is difficult to increase the charge amount, and the toner becomes black, which is the color of the magnetic powder, and It is difficult to colorize.
[0004]
In contrast, the non-magnetic one-component developing method uses a non-magnetic one-component developer (toner) that does not contain a magnetic powder and has a high electric resistance, and forms a thin layer of toner on a developing roll. The toner is charged by frictional charging between the toner and a developing roll or a developing blade, and the electrostatic latent image is visualized by the toner. However, in the non-magnetic one-component developing method, if the fluidity of the toner is low, the supply of the toner becomes insufficient, and the image is blurred or the image density is reduced. Further, in the non-magnetic one-component developing method, since the toner is charged by frictional charging, if the toner has low chargeability, fogging is likely to occur.
[0005]
On the other hand, among the toner production methods used in these developing methods, the toner produced by the pulverization method is obtained by melt-kneading a colorant, a charge control agent, an offset preventing agent, and the like in a thermoplastic resin and uniformly dispersing the same. , Pulverized, and then classified to a desired particle size. In the pulverization method, particles having a wide particle size distribution are easily formed. In particular, when the toner is reduced in size, a large amount of excessively pulverized fine particles is generated. For a toner to exhibit satisfactory development characteristics, its particle size distribution must be somewhat narrow. Therefore, it is necessary to classify the particles obtained by grinding to remove coarse particles and fine particles. Therefore, in the pulverization method, the yield is poor and the toner yield is low. Further, it is difficult to produce spherical and uniform toner particles by the pulverization method.
[0006]
On the other hand, when the toner is manufactured by the suspension polymerization method, the colored polymer particles (toner) can be directly manufactured by the polymerization without requiring a pulverizing step. In the suspension polymerization method, a polymerizable monomer is prepared by uniformly dissolving or dispersing a colorant, a charge control agent, an oil-soluble polymerization initiator, and other additives in a polymerizable monomer, and then By dispersing in a water-based dispersion medium containing a dispersion stabilizer using a stirrer to form fine droplet particles of the polymerizable monomer composition, and thereafter, the temperature is raised to perform suspension polymerization. Thus, a polymerized toner having a desired particle size is obtained. This polymerized toner is spherical, has a uniform surface, and exhibits good development characteristics.
Therefore, in recent years, a non-magnetic one-component developing method that is easy to miniaturize and color is developed, and a developing method that uses a polymerized toner that is easily obtained as uniformly charged spherical particles as a non-magnetic one-component developer has attracted attention. ing. In addition, the non-magnetic one-component developing method and the cleaner-less developing method are advantageous in reducing the cost of parts and reducing the size because no cleaning device is required. In this cleanerless system, the amount of residual toner on the photoreceptor after toner transfer is required to be small because there is no cleaning device. However, since the polymerized toner is spherical, the charge is uniform and high transferability is obtained. Can be satisfied.
[0007]
However, in the non-magnetic one-component developing system, it is required that the toner has high performance. In other words, in the non-magnetic one-component developing method, the toner has excellent fluidity and stable charging properties, and does not cause fogging on the photoreceptor or decrease in image density for a long period of time, so that high quality printing can be performed. It needs to be possible. However, it has been a difficult task to stably provide a high charge amount to the polymerized toner.
By the way, generally, a positive or negative charge is stored in a toner according to the polarity of an electrostatic latent image to be developed. In order to retain charge in the toner, the frictional charging property of the binder resin can be used.However, the frictional charging alone has a low chargeability of the toner. Improves chargeability. Known charge control agents include, for example, metal complex dyes, nigrosine dyes, quaternary ammonium salts, and polyamine resins.
[0008]
Conventionally, as an improvement proposal regarding a charge control agent, for example, (1) Japanese Patent Application Laid-Open No. 1-259371 discloses a method for electrophotography by using a combination of a nigrosine having a high charging power and a quaternary ammonium salt having a low charging power. A method of adjusting the charge amount of the toner has been proposed. In the examples of this publication, a toner is produced by kneading polystyrene, carbon black as a colorant, nigrosine and a quaternary ammonium salt as a charge controlling agent, and polypropylene as a release agent, and then performing a pulverization / classification process. It is shown. The ratio of nigrosine in the toner is 4% by weight, and the ratio of quaternary ammonium salt is 1% by weight.
[0009]
Also, (2) Japanese Patent Publication No. 1-54694 proposes to use a salt forming compound of a quaternary ammonium salt and naphtho-sulfonic acid as a charge control agent. This salt forming compound (a kind of quaternary ammonium salt) has good thermal stability and compatibility with the binder resin, hardly decreases the chargeability, and can provide a positive charge to the toner. In each of the examples of the publication, 100 parts by weight of a styrene-n-butyl methacrylate resin are kneaded with 2 to 5 parts by weight of various colorants and a salt forming compound, and pulverized and classified to produce a toner for electrostatic charge development. An example is shown. (3) JP-A-3-7948 discloses that a nigrosine dye and a quaternary ammonium salt (the above-mentioned salt-forming compound) are used in combination to minimize deterioration over time in image quality and deterioration due to environment, and to provide excellent charging characteristics. It has been proposed to use such a toner for electrostatic charge development. The publication describes that 0.5 to 5 parts by weight of a quaternary ammonium salt and 0.01 to 5 resins of a nigrosine dye are used in combination with 100 parts by weight of the resin. In each example of the publication, 3 to 5 parts by weight of a quaternary ammonium salt and 0.1 to 1 part by weight of a nigrosine dye are kneaded with 100 parts by weight of a styrene resin, and the mixture is ground and classified. It is shown that toner was obtained.
[0010]
However, all of these prior art improvement proposals actually relate to toners obtained by the pulverization method, and therefore, the particle size distribution is wide, the toner yield is reduced by classification, or spherical and uniform particles are obtained. It has problems associated with the above-mentioned pulverization method, for example, it cannot be performed. In addition, even when a nigrosine dye and a quaternary ammonium salt (the above-mentioned salt-forming compound) are used in combination, the amount of use thereof is large. In particular, since quaternary ammonium salts (salt-forming compounds) are hardly soluble in monomers, it is satisfactory even if these conventional techniques relating to the pulverization method are simply applied to a method for producing a polymerized toner by a suspension polymerization method. A polymerized toner having chargeability cannot be obtained.
[0011]
[Problems to be solved by the invention]
An object of the present invention is a polymerized toner obtained by a suspension polymerization method, which has stable chargeability, has good initial print quality, and has excellent image quality stability in continuous printing. Is to provide.
Another object of the present invention is to provide a polymerized toner having excellent fluidity and stable chargeability suitable as a non-magnetic one-component developer.
The present inventors have conducted intensive studies to overcome the problems of the prior art, and as a result, in the process of producing a polymerized toner by a suspension polymerization method, a nigrosine dye and a specific quaternary ammonium salt were each limited. It has been found that a polymer toner having excellent initial printing quality and excellent image quality stability in continuous printing can be obtained by using the polymer toner in a small proportion. By using a polymerizable monomer having high hydrophobicity, a highly polar nigrosine dye and a quaternary ammonium salt are collected on the surface of the droplet of the polymerizable monomer composition, and as a result, these charge control agents Is used in an extremely small amount as compared with the pulverized toner, and excellent chargeability can be imparted to the polymerized toner. If the quaternary ammonium salt or both the quaternary ammonium salt and the nigrosine dye are used after being pulverized into particles having a volume average particle size of 5 μm or less, these charge control agents can be more uniformly dispersed in the polymerized toner. Can be dispersed.
The present invention has been completed based on these findings.
[0012]
[Means for Solving the Problems]
According to the present invention, a composition containing at least a polymerizable monomer, a colorant, and a charge control agent is not subjected to suspension polymerization in an aqueous dispersion medium.Used for non-magnetic one-component developmentIn a polymerized toner, 0.01 to 1.0 part by weight of a nigrosine dye is used as a charge control agent based on 100 parts by weight of a polymerizable monomer and the following formula (I)
[0013]
Embedded image

(Where R¹Is an alkyl group having 1 to 8 carbon atoms, R²And R³Is independently an alkyl group having 1 to 18 carbon atoms, R⁴Is an alkyl group having 1 to 8 carbon atoms or a benzyl group. )
0.01 to 0.4 parts by weight of a quaternary ammonium salt represented by the formula: and the weight ratio of the quaternary ammonium salt to the nigrosine dye is in the range of 0.01 to 5.0. FeatureUsed for non-magnetic one-component developmentA polymerized toner is provided.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In the polymerized toner of the present invention, a composition containing at least a polymerizable monomer, a colorant, and a charge control agent is charged into an aqueous dispersion medium containing a dispersion stabilizer, and stirred to form droplet particles. It can be produced by granulating, then raising the temperature to carry out suspension polymerization. As the polymerization initiator, an oil-soluble polymerization initiator is used, and is usually added to the polymerizable monomer composition.
[0015]
Polymerizable monomer
As the polymerizable monomer used in the present invention, a monomer having a vinyl group is preferably used. Specific examples of the polymerizable monomer include, for example, aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and vinyltoluene; non-polymerizable monomers such as acrylonitrile and methacrylonitrile; Saturated nitriles; unsaturated (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate Esters; acrylic acids such as acrylic acid and methacrylic acid; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; Vinyl acetate, vinyl propionate, etc. Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; nitrogen-containing vinyl compounds such as 2-vinyl pyridine, 4-vinyl pyridine and N-vinyl pyrrolidone; Conjugated diolefins such as butadiene and isoprene; and the like. These polymerizable monomers can be used alone or in combination of two or more.
Among these monomers, aromatic vinyl monomers such as styrene and / or unsaturated (meth) acrylates are preferred because of their high hydrophobicity. Styrene-acrylate copolymers are particularly preferred. If the polymerizable monomer has high hydrophobicity, the highly polar nigrosine dye and the quaternary ammonium salt are collected on the surface of the toner, so that the amount used is smaller than that of the conventional pulverized toner. That is, as compared with the conventional pulverized toner, even if the use ratio of the nigrosine dye is as small as 1/10 or less, and the use ratio of the quaternary ammonium salt is as small as about 1/2 to 1/10, the chargeability can be sufficiently satisfied. Can be obtained.
[0016]
Colorant
Examples of the coloring agent used in the present invention include carbon black, nigrosine base, aniline blue, calco oil blue, chrome yellow, ultramarine blue, orient oil red, phthalocyanine blue, malachite green oxalate, rhodamine B, crystal violet and the like. Pigments and dyes. The dye / pigment is used in an amount of usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.
Metal oxides such as titanium oxide, silicon dioxide and zinc oxide as coloring agents; magnetic particles such as iron, cobalt, nickel, iron sesquioxide, iron sesquioxide, iron manganese oxide, zinc iron oxide and nickel iron oxide And the like can be used in an appropriate amount. When using these metal oxides or magnetic powders as coloring agents, it is preferable to use fine particles of 1 μm or less.
[0017]
Oil-soluble polymerization initiator
Any oil-soluble polymerization initiator may be used as long as it is soluble in the monomer used. For example, methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide Peroxides such as benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropylperoxydicarbonate, di-t-butyldiperoxyisophthalate; 2,2'-azobis ( Azo compounds such as 2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azbis (1-cyclohexanecarbonitrile). The oil-soluble polymerization initiator is used in an amount of usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer. The polymerization initiator can be added in advance to the polymerizable monomer composition, but in some cases, can be added to the suspension after the completion of the granulation step.
[0018]
Various additives
A molecular weight modifier, a crosslinkable monomer, a release agent, and the like can be added to the polymerizable monomer composition.
Examples of the molecular weight regulator include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, and n-octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide; and the like. These molecular weight modifiers can be added before the start of the polymerization or during the polymerization. The molecular weight modifier is used in an amount of usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.
Examples of the crosslinkable monomer include polyfunctional monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, glycidyl (meth) acrylate, and trimethylolpropane tri (meth) acrylate. These crosslinkable monomers can be added before the start of the polymerization or during the polymerization. The crosslinkable monomer is used in an amount of usually 0.01 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.
Examples of the release agent include low molecular weight polyolefins such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene. The release agent is used in an amount of usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.
A lubricant such as oleic acid and stearic acid; a dispersing aid such as a silane-based or titanium-based coupling agent; and the like are present in the polymerizable monomer composition for the purpose of uniformly dispersing the colorant in the toner particles. You may let it. Such lubricants and dispersing aids are usually used at a ratio of about 1/1000 to 1/50 based on the weight of the colorant.
[0019]
Charge control agent
In the present invention, a nigrosine dye and a quaternary ammonium salt represented by the above formula (I) are used as the charge control agent.
As the nigrosine dye, known dyes can be used, for example, Bontron N series (N-01, N-02, N-03, N-04, N-05, N-07) manufactured by Orient Chemical Co., Ltd. , N-09, N-10, N-11, N-13, N-EX), Orient Spirit Black AB, Orient Spirit Black SB, Solvent Black # 5, Solvent Black # 7; Spirit manufactured by Sumitomo Chemical Co., Ltd. Black No. 850, Spirit Black No. 900 and the like.
Specific examples of the quaternary ammonium salt represented by the formula (I) include the compounds of the following formulas (1) to (10).
[0020]
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[0021]
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[0022]
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[0023]
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[0024]
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[0025]
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[0026]
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[0027]
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[0028]
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[0029]
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[0030]
As such a quaternary ammonium salt, for example, P series such as P-51 and P-53 manufactured by Orient Chemical Co., Ltd. can be used.
In the present invention, 0.01 to 1.0 part by weight of a nigrosine dye and 0.01 to 0.4 part by weight of a quaternary ammonium salt represented by the formula (I) are added to 100 parts by weight of the polymerizable monomer. Is used in a weight ratio of quaternary ammonium salt / nigrosine dye in the range of 0.01 to 5.0. The resulting polymerized toner is positively charged.
When only a nigrosine dye is used as the charge control agent of the positively charged toner, the initial print quality can be satisfied. However, as the number of prints increases, the charge amount decreases and fog on the photoreceptor increases. When only a quaternary ammonium salt is used, the change in the charge amount in continuous printing is small, but the charge amount of the toner is low, and satisfactory print quality cannot be obtained. By using both of them, it is possible to obtain excellent initial printing quality and obtain stable image quality in continuous printing.
[0031]
If the ratio of the nigrosine-based dye to 100 parts by weight of the polymerizable monomer exceeds 1.0 part by weight, fog on the photoreceptor is large, and the image density is reduced. You cannot get the quantity.
If the proportion of the quaternary ammonium salt exceeds 0.4 parts by weight with respect to 100 parts by weight of the polymerizable monomer, the charge amount of the toner decreases, the fog on the photosensitive member increases, the image density decreases, When the amount is less than the weight part, as the number of printed sheets increases, the charge amount decreases, fog on the photoconductor increases, and the image density also decreases. The proportion of the quaternary ammonium salt is preferably 0.02 to 0.3 parts by weight.
The weight ratio of the quaternary ammonium salt to the nigrosine dye must be in the range of 0.01 to 5.0. If the weight ratio exceeds 5.0, the charge amount of the toner becomes insufficient, fog on the photoconductor increases, and the image density also decreases. If the weight ratio is less than 0.01, fog on the photoconductor increases, The concentration also decreases. This weight ratio is preferably between 0.05 and 4.0.
[0032]
The present invention is characterized in that the nigrosine-based dye and the quaternary ammonium salt are used in such a limited small proportion. In particular, when a highly hydrophobic monomer such as styrene or acrylate is used as a polymerizable monomer, highly polar nigrosine and a quaternary ammonium salt are collected on the surface of the toner. Less than toner. As described above, the polymerized toner of the present invention has a sufficient chargeability with a nigrosine dye and a quaternary ammonium salt in a small amount of about 1/2 to 1/10 as compared with the conventional pulverized toner. And stability of image quality in continuous printing can be achieved.
[0033]
Further, since the quaternary ammonium salt is hardly soluble in the polymerizable monomer, it is preferable that the quaternary ammonium salt is pulverized to a smaller particle size than the resulting polymerized toner. More specifically, by setting the volume average particle diameter of the quaternary ammonium salt contained in the polymerized toner to 5 μm or less, the quaternary ammonium salt can be dispersed evenly in each particle of the polymerized toner. Nigrosine dyes are also hardly soluble in polymerizable monomers, and thus are preferably ground to a smaller particle size than the resulting polymerized toner. When a polymerized toner is manufactured using a coarse charge control agent, the dispersion of the charge control agent in individual polymerized toner particles becomes non-uniform, and as a result, the charge amount distribution of the polymerized toner becomes broad, and fog and the like are reduced. Inconvenience is likely to occur. Therefore, these charge control agents are preferably used after pulverized and classified to a volume average particle size of 5 μm or less. However, a material having a volume average particle size of 5 μm or less can be prepared and used at the stage of preparing the raw material. The volume average particle size is a volume average particle size (dv) measured by a Coulter counter (manufactured by Coulter).
[0034]
Suspension polymerization method
The polymerizable monomer composition is charged into an aqueous dispersion medium containing a dispersion stabilizer, stirred to granulate droplet particles, and then subjected to suspension polymerization by raising the temperature.
In the present invention, water or an aqueous liquid containing water as a main component can be used as the aqueous dispersion medium. Examples of the dispersion stabilizer include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; poorly water-soluble salts such as calcium phosphate, barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, and magnesium carbonate; Molecular substances; metal oxides such as aluminum oxide and titanium oxide; metal hydroxides such as aluminum hydroxide, magnesium hydroxide and ferric hydroxide; The dispersion stabilizers can be used alone or in combination of two or more. The dispersion stabilizer is used in an amount of usually 0.1 to 20 parts by weight, preferably 0.5 to 18 parts by weight, based on 100 parts by weight of the aqueous dispersion medium.
[0035]
In the present invention, the ratio of the polymerizable monomer composition and the aqueous dispersion medium is not particularly limited, but considering the ease of granulation in the dispersion medium and the dispersion stability of the particles during the polymerization reaction, The concentration of the polymerizable monomer composition in the system is usually in the range of 5 to 50% by weight, preferably 10 to 40% by weight, more preferably about 20 to 35% by weight.
After the granulating step, the granulated polymerizable monomer composition is subjected to suspension polymerization by a conventional method to form a polymerized toner. After completion of the suspension polymerization reaction, the dispersion stabilizer remaining on the particle surface is removed by usual pickling and washing with water, followed by dehydration and drying to obtain a polymerized toner. The volume average particle size of the polymerized toner is usually 1 to 50 μm, preferably 5 to 30 μm, more preferably 2 to 20 μm. A fluidizing agent such as colloidal silica can be externally added to the polymerized toner.
[0036]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
In the following Examples and Comparative Examples, “parts” indicates parts by weight.
The measuring method of the physical properties is as follows.
(1) Measurement of charge amount
This is a value obtained by suctioning the toner on the developing roll using a suction-type charge amount measuring device and measuring the charge amount per unit mass.
(2) Measurement of photoreceptor fog
The toner in the fog area on the photoconductor drum is transferred to paper with a mending tape, and the reflectance value measured with a whiteness meter is used to measure the reflectance when only the mending tape is attached to the paper using a whiteness meter. It is the value subtracted from the measured value.
(3) Measurement of image density
Evaluation of image density was performed by measuring "black solid portion" using a Macbeth reflection densitometer.
[0037]
[Example 1]
Styrene 70 parts
30 parts of n-butyl acrylate
7 parts carbon black
(Monarch 120, manufactured by Cabot)
Charge control agent
(1) 0.01 parts of nigrosine dye
(N-05, manufactured by Orient Chemical Co., Ltd.)
(2) Quaternary ammonium salt 0.02 parts
(P-53, manufactured by Orient Chemical Co., Ltd.)
0.3 parts of divinylbenzene
2,2'-azobisisobutyronitrile 2 parts
2 parts of polypropylene
(Viscole 550P, manufactured by Sanyo Chemical Co., Ltd.)
However, the nigrosine dye N-05 was used after pulverizing with a jet mill in advance and then classifying to a volume average particle size of 2.8 μm. In addition, the quaternary ammonium salt P-53 was pulverized by a jet mill in advance, then classified, and the one having a volume average particle diameter of 3.0 μm was used.
[0038]
The above components were stirred and mixed by a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), which is a mixer having a high shearing force, to prepare a uniformly dispersed polymerizable monomer composition. On the other hand, 3 parts of calcium phosphate was added to 250 parts of distilled water to obtain a dispersion in which the calcium phosphate was finely dispersed. The polymerizable monomer composition described above was added to the calcium phosphate dispersion, and high shear stirring was performed with a TK homomixer to granulate droplets of the polymerizable monomer composition. The aqueous dispersion of the granulated polymerizable monomer composition was placed in a reactor equipped with a stirring blade, and polymerized at 65 ° C. for 8 hours with stirring. The polymer dispersion thus obtained was sufficiently washed with acid and water, then separated and dried to obtain a toner material as colored particles. When the particle size of the obtained colored particles was measured by a Coulter counter (manufactured by Coulter Corporation), the volume average particle size was 9.0 μm.
To 100 parts of the polymerized toner obtained as described above, 0.5 part of colloidal silica (trade name: HVK2150, manufactured by Hoechst Co.) was added and mixed with a Henschel mixer to obtain a developer.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact developing system positive charging printer. As a result, good image quality was obtained at the initial stage, and the initial charge amount was 18 μC / g. Subsequently, continuous printing of 20,000 sheets was performed. As a result, no change was observed in the image density and the fog of the photosensitive member, and good image quality was obtained. At this time, the charge amount was 16 μC / g, and almost no change was observed.
[0039]
[Example 2]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1.
The thus obtained developer was evaluated for printing with a non-magnetic one-component contact developing system positively charged printer. As a result, good image quality was obtained at the initial stage, and the initial charge amount was 27 μC / g. Subsequently, continuous printing of 20,000 sheets was performed. As a result, no change was observed in the image density and the fog of the photosensitive member, and good image quality was obtained. At this time, the charge amount was 23 μC / g, and almost no change was observed.
[0040]
[Example 3]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1.
When the thus obtained developer was evaluated for printing by a positive charging printer of a non-magnetic one-component contact developing system, good image quality was obtained at the initial stage, and the initial charge amount was 20 μC / g. Subsequently, continuous printing of 20,000 sheets was performed. As a result, no change was observed in the image density and the fog of the photosensitive member, and good image quality was obtained. At this time, the charge amount was 18 μC / g, and almost no change was observed.
[0041]
[Example 4]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact development type positive charging printer. As a result, good image quality was obtained at the initial stage, and the initial charge amount was 32 μC / g. Subsequently, continuous printing of 20,000 sheets was performed. As a result, no change was observed in the image density and the fog of the photosensitive member, and good image quality was obtained. At this time, the charge amount was 25 μC / g, and almost no change was observed.
[0042]
[Comparative Example 1]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1. In this example, only a nigrosine dye was used as a charge control agent, and no quaternary ammonium salt was used.
When the thus obtained developer was evaluated for printing by a positive charging printer of a non-magnetic one-component contact developing system, good image quality was obtained at the initial stage, and the initial charge amount was 25 μC / g. Subsequently, continuous printing was performed on 20,000 sheets. As a result, a decrease in image density and an increase in fog of the photoreceptor were observed. At this time, the charge amount was 5 μC / g, and a decrease in the charge amount was confirmed.
[0043]
[Comparative Example 2]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1. In this example, only a quaternary ammonium salt was used as a charge control agent, and no nigrosine dye was used.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact developing system positively charged printer. As a result, the image density was low at the initial stage, and the image was blurred and insufficient. The charge amount at this time was 5 μC / g.
[0044]
[Comparative Example 3]
A non-magnetic one-component developer was obtained in the same manner as in Example 1, except that the use ratio of the charge control agent was changed as shown in Table 1. In this example, the weight ratio of the quaternary ammonium salt to the nigrosine dye was as large as 10.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact developing system positively charged printer. As a result, the image density was low at the initial stage, and the image was blurred and insufficient. The charge amount at this time was 5 μC / g.
[0045]
[Comparative Example 4]
A non-magnetic one-component developer was obtained in the same manner as in Example 1 except that the use ratio of the charge control agent was changed as shown in Table 1. In this example, the use ratio of the nigrosine dye was as large as 2.0 parts by weight.
The developer obtained above was evaluated for printing by a non-magnetic one-component contact development type positive charging printer. As a result, an increase in photoreceptor fog was observed at an early stage. The initial charge amount at this time was 50 μC / g.
[0046]
[Comparative Example 5]
A non-magnetic one-component developer was obtained in the same manner as in Example 1, except that the use ratio of the charge control agent was changed as shown in Table 1. In this example, the use ratio of the quaternary ammonium salt was as large as 1.0 part by weight.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact developing system positively charged printer. As a result, the image density was low at the initial stage, and the image was blurred and insufficient. The charge amount at this time was 5 μC / g.
[0047]
[Comparative Example 6]
Styrene / n-butyl acrylate / divinylbenzene
(Weight ratio 85/15 / 0.3) 100 parts of copolymer
7 parts carbon black
(Monarch 120, manufactured by Cabot)
Charge control agent
(1) 0.3 parts of nigrosine dye
(N-05, manufactured by Orient Chemical Co., Ltd.)
(2) Quaternary ammonium salt 0.2 parts
(P-53, manufactured by Orient Chemical Co., Ltd.)
2 parts of polypropylene
(Viscole 550P manufactured by Sanyo Chemical Co., Ltd.)
The above components were blended, kneaded, pulverized, and classified to obtain a black toner having a volume average particle size of 9.1 μm. To 100 parts of the toner particles thus obtained, 0.5 part of colloidal silica (trade name: HVK2150, manufactured by Hoechst Co.) was added and mixed with a Henschel mixer to obtain a developer.
The thus obtained developer was evaluated for printing by a non-magnetic one-component contact developing system positively charged printer. As a result, the image density was low at the initial stage, and the image was blurred and insufficient. The charge amount at this time was 5 μC / g.
[0048]
[Table 1]

[0049]
【The invention's effect】
According to the present invention, a polymerized toner obtained by a suspension polymerization method, which has stable chargeability, has good initial print quality, and has excellent image quality stability in continuous printing Is provided. The polymerized toner of the present invention has excellent fluidity and stable charging properties, and is particularly suitable as a non-magnetic one-component developer.

Claims (1)

At least a polymerizable monomer, a colorant, and a composition containing the charge control agent Ri name by suspension polymerization in an aqueous dispersion medium, the polymerized toner that is used in the non-magnetic one-component developing method, a charge control agent The nigrosine-based dye is used in an amount of 0.01 to 1.0 part by weight based on 100 parts by weight of the polymerizable monomer and the following formula (I)

(Wherein, R ¹ is an alkyl group having 1 to 8 carbon atoms, R ² and R ³ are each independently an alkyl group having 1 to 18 carbon atoms, and R ⁴ is an alkyl group having 1 to 8 carbon atoms. Or a benzyl group.)
0.01 to 0.4 parts by weight of a quaternary ammonium salt represented by the formula: and the weight ratio of the quaternary ammonium salt to the nigrosine dye is in the range of 0.01 to 5.0. Characterized polymerized toner used for non-magnetic one-component development .