JP4097312B2 - Toner for electrostatic latent image development, method for producing the same, electrostatic latent image developer, and image forming method - Google Patents

Description

【００５０】
（実施例１）
【００５１】
（Ａ）色材分散液の調整
下記材料組成の分散液に、ガラスビーズを加えサンドミル分散機に装着した。分散容器回りを冷却しながら、高速撹拌モードで３時間分散し、その後酢酸エチルで希釈し色材濃度１０重量％濃度の色材分散液を調整した。
マゼンタ顔料: (C.I. ピグメントレッド122,ECR186Y;大日精化社製) ８８部
シナージスト: ジメチルアミノエチルキナクリドン ２部
高分子分散剤: ポリカプロラクトン（分子量2000） １０部
酢酸エチル １００部
【００５２】
（Ｂ）微粒子化ワックスの調整
下記材料を、撹拌羽根を装着し、容器回りに熱媒を循環させる機能を持った分散機に投入した。毎分８３回転で撹拌しながら徐々に温度を上げてゆき、１００℃まで温度を上げ、１００℃に保ったまま３時間撹拌した。次に撹拌を続けながら毎分約２℃の割合で室温まで冷却し、微粒子化したワックスを析出させた。レーザ回折／散乱粒度分布測定装置「ＬＡ−７００」（堀場製作所社製）を用いてワックスの平均粒度を測定すると約１．０２μｍであった。このワックス分散液を高圧乳化機「APV GAULIN HOMOGENIZER 15MR 型」（APPVGAULIN社製）を用い、圧力５．１０×１０⁵ Ｐａ（５００ＫＧ／ＣＭ２）で再度分散を行った。同様にワックス粒度を測定したところ０．８１μｍであった。作製した微粒子化ワックスの分散液は、ワックスの重量濃度が１５重量％濃度になるように酢酸エチルで希釈した。
パラフィンワックス: （融点: 85℃、融解潜熱: 193mJ/mg） １５部
トルエン ８５部
【００５３】
（Ｃ）油相溶液の調整
下記材料を、結着樹脂が溶剤に充分に溶解することを確認したのち混合し、混合物をホモミキサー「エースホモジナイザー」（日本精機社製）に投入し、毎分１５０００回転で２分間撹拌し、均一な油相溶液を調整した。
結着樹脂Ａ: ７０部
結着樹脂Ｂ: ３０部
色材分散液: （顔料濃度10重量%) ５０部
微粒子化ワックスの分散液: （ワックス濃度15重量%) ３３部
酢酸エチル ３２部
【００５４】
（Ｄ）水相溶液の調整
水相溶液として用いる、「炭酸カルシウム水溶液」と「カルボキシルメチルセルロース水溶液」とを調整した。
（Ｄ−１）炭酸カルシウム水溶液の調整
下記材料を、ボールミルで４日間撹拌し、炭酸カルシウム水溶液を得た。上述したレーザ回折/ 散乱粒度分布測定装置「ＬＡ−７００」（堀場製作所社製）を用いて炭酸カルシウムの平均粒度を測定すると約０．０８μｍであった。
炭酸カルシウム: （平均粒径０．０３μｍ) ６０部
純水 ４０部
（Ｄ−２）カルボキシルメチルセルロース水溶液の調整
カルボキシルメチルセルロース「セロゲンＢＳＨ」（第一工業製薬社製) 2 部を、純水９８部に溶解させ、カルボキシルメチルセルロース水溶液を得た。
【００５５】
（Ｅ）トナーの造粒
油相溶液６０部、炭酸カルシウム水溶液１０部、およびカルボキシルメチルセルロース水溶液３０部を、コロイドミル（日本精機社製）に投入し、ギャップ間隔１．５ｍｍ、毎分８０００回転で２０分間乳化をおこなった。次に、上記乳化物を、ロータリーエバポレータに投入、３９９０Ｐａ（30mmHg）の減圧下、室温で３時間脱溶媒を行った。その後１２Ｎ塩酸をｐＨ２になるまで加え、炭酸カルシウムをトナー表面から除去した。その後、１０Ｎの水酸化ナトリウムをｐＨ１０になるまで加え、さらに超音波洗浄槽中で撹拌機で撹拌しながら一時間撹拌を継続した。さらに遠心沈降を行い、その上澄みを三回交換して洗浄した後、乾燥してマゼンタトナーを得た。
コールターカウンター「ＴＡ−II型」（コールター社製) を用い測定したトナーの体積平均粒度は６．５μｍ、粒度分布の指標であるＧＳＤ（体積平均粒度である、d84/d16 のルートを求めたもの）は１．２２、形状係数ＭＬＳ２は１０７であった。
【００５６】
（Ｆ）現像剤の調整
（Ｅ）で作製したトナーに、シリカ「Ｒ９７２」（日本アエロジル社製）０．５重量部をヘンシェルミキサーを用いて添加した。このトナーにキャリアコアとして「Ｆ３００」（パウダーテック社製）にポリメチルメタクリレートを０．５重量部、ニーダでコートしたキャリアを作製し、トナー重量濃度で８％になるように調整し、マゼンタカラー現像剤とした。
【００５７】
（実施例２）
色材分散液を調整する際に、色材とシナージストを以下のように変更した他は、実施例１と同様に、シアントナーを作製した。また、このトナーを用い、実施例１と同様にしてシアンカラー現像剤を得た。
シアン顔料: (C.I. ピグメントブル-15:3,
シアンインブル-4933M; 大日精化社製) ８８部
シナージスト: １−アミノアントラキノン−２−カルボン酸 2 部
【００５８】
（実施例３）
色材分散液を調整する際に、色材とシナージストを以下のように変更した他は、実施例１と同様に、イエロートナーを作製した。また、このトナーを用い、実施例１と同様にしてイエローカラー現像剤を得た。
イエロー顔料: (C.I. ピグメントイエロ-180, ヘキスト社製) ８８部
シナージスト: 下記化合物(PはC.I.PIGMENT YELLOW180) 2 部
【００５９】
【化１】

【００６０】
（実施例４）
色材分散液を調整する際に、色材とシナージストを以下のように変更した他は、実施例１と同様に、ブラックトナーを作製した。また、このトナーを用い、実施例１と同様にしてブラックカラー現像剤を得た。
カーボンブラック(#25, 三菱化学社製) ８８部
シナージスト: ジメチルアミノエチルキナクリドン 2 部
【００６１】
（実施例５）
色材分散液を調整する際に、高分子分散剤を１２−ヒドロキシステアリン酸の重合体（酸価２０ｍｇＫＯＨ／ｇ）に替えた以外は、実施例１と同様に、マゼンタトナーを作製した。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。
【００６２】
（実施例６）
結着樹脂を、結着樹脂Ａと結着樹脂Ｂから結着樹脂Ｃと結着樹脂Ｄに変え、シナージストをジヒドロキシキナクリドンに、高分子分散剤をポリカプロラクトン（分子量5000）に替えた以外は、実施例１と同様に、マゼンタトナーを作製した。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。
【００６３】
（実施例７）
シナージストをジメチルアミノエチルキナクリドンに替えた以外は、実施例６と同様に、マゼンタトナーを作製した。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。
【００６４】
（実施例８）
結着樹脂を、線状ポリエステルである結着樹脂Ｅのみにした以外は、実施例５と同様に、マゼンタトナーを作製した。顔料の平均粒度を測定すると０．３μｍであった。トナーの平均粒度は７．８μｍ、ＧＳＤは１．３５であった。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。実施例1 同様に現像剤を調整し実機での評価を行った。ＯＨＰ画像は、鮮明で良好なものであった。画像のホットオフセット温度は１５５℃で発生し、オイルレス定着生は不十分であった。連続評価をすると、８０００枚まで画像劣化の少ない良好なものであった。また機械内の汚れも発生しなかった。高温高湿での画像も画像乱れがなく良好なものであった。トナー熱保存性指数は１９％であった。
【００６５】
（参考例）旧実施例９
結着樹脂Ａ ６０部
結着樹脂Ｂ ２６部
マゼンタ顔料：（Ｃ．Ｉ．ピグメントレッド１２２、ＥＣＲ１８６Ｙ、
大日精化社製） ６部
シナージスト：ジメチルアミノエチルキナクリドン ２部
高分子分散剤：ポリカプロラクトン（分子量２０００） ２部
パラフィンワックス：（融点：８５℃、融解潜熱：１９３mJ/mg ） ４部
上記組成の混合物をＢＲバンバリーミキサーを用い、溶融混練した後、フィッツミルを用いて粗粉砕し、さらにジェットミルを用い微粉砕した。この粉砕トナーを風力式分級機を用いて分級し、不定形トナーを作製した。
トナー平均径は、７．２μｍ、ＭＬＳ２は１５４、顔料分散径０．３μｍであった。実施例１と同様にしてマゼンタカラー現像剤を得た。また実施例１と同様に現像剤を調整し実機での評価を行った。ＯＨＰ画像は、鮮明で良好であった。画像のホットオフセットは２００℃で未発生であった。連続評価を行っても８０００枚まで画像劣化が無く、また機械内汚染の少ない良好な画像が得られた。
【００６６】
（実施例１０）
図４は、本発明の画像形成方法に使用可能な非磁性一成分現像ユニットの構造を示す概略図である。図４に示す非磁性一成分現像ユニットは、トナー溜め１１と、供給ロール１２、シール材１３、現像ロール１４、および規制ブレード１５から構成されている。
実施例１に記載のトナーと図４に示す非磁性一成分現像ユニットを登載した「レーザープレス4161」（富士ゼロックス社製）改造機を用いて画質の評価を行った。ハードロールに対し、定着温度１５５℃での、ベタ部画像では入射測定角が６０／６０の条件で、トナー付着量が０．６〜０．７ｍｇ／ｃｍの時、光沢度はどの色も２０以上の高光沢を示した。またオフセット温度も２１０℃以上でも発生しなかった。ＯＨＰ画像も鮮明で良好であった。
【００６７】
（比較例１）
シナージストと高分子分散剤の両方を使用しない以外は、すべて実施例２と同様にしてシアントナーを作製した。顔料の平均粒度を測定すると約０．８μｍであった。トナーの平均粒度は８．３μｍ、ＧＳＤは１．３５であった。また、このトナーを用い、実施例２と同様にシアンカラー現像剤を得た。
【００６８】
（比較例２）
シナージストを使用しない以外は、すべて実施例１と同様にしてマゼンタトナーを作製した。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。この現像剤を評価したところ、ＯＨＰ画像は、ベタ画像部は良好であるが画像面積率２０〜３０％の部分が暗く十分な発色が得られなかった。
【００６９】
（比較例３）
シナージストを用い無い以外は、すべて参考例と同様にしてトナーを作製した。顔料分散径は１．５μｍであった。また、このトナーを用い、実施例１と同様にしてマゼンタカラー現像剤を得た。この現像剤を評価したところ、ＯＨＰ画像は暗く、画像品位の低いものであった。
【００７０】
［トナーの評価方法］
得られたトナーおよび現像剤について、下記の方法により、評価を行った。評価結果をトナー物性（トナーの体積平均粒度、粒度分布の指標であるＧＳＤ、形状係数ＭＬＳ２）とともに表２に示す。
【００７１】
【表２】

【００７２】
（１）ＯＨＰ透過性および発色性
各色について得られた現像剤を用い、「Ａ Ｃｏｌｏｒ ６３５」（富士ゼロックス社製）を改造した画像出力評価装置を用いて、熱定着ロールにオイルを供給せずにＯＨＰシート上、および普通紙上に画像形成を行った。（図１に画像出力評価装置の概略を示す。）画像形成の諸条件を下記に示す。現像ロール、感光体と現像ロールの間隔、感光体と現像ロールの間隔、現像バイアスについては、各色の現像器について共通とした。
【００７３】
感光体 ＯＰＣ（φ８４）
ＲＯＳ光学系 ＬＥＤ（４００ｄｐｉ）
プロセス速度 １６０ｍｍ／ｓ
潜像電位 背景部＝−５５０Ｖ、画像部＝−１５０Ｖ
現像ロール マグネット固定、スリーブ回転、マグネット磁束密度＝５００Ｇ（スリーブ上）、スリーブ径＝φ２５、スリーブ回転速度＝３００ｍｍ／ｓ
感光体と現像ロールの間隔 ０．５ｍｍ
現像剤層層厚規制部材と現像ロールとの間隔 ０．５ｍｍ
現像バイアス ＤＣ成分＝−５００Ｖ、ＡＣ成分＝１．５ｋＶＰ−Ｐ（８ｋＨｚ）
転写条件 コロトロン転写（ワイヤ径＝８５μｍ）
定着条件 フッ素ロール、オイル供給無し
環境条件 常温常湿（２３℃，５０％ＲＨ）
および高温高湿（２８℃，８５％ＲＨ）
【００７４】
ＯＨＰ透過性の評価は、ＯＨＰシート上に作像した画像の、各色ごとに以下の波長での光透過率を分光光度計「Ｕ−３２１０」（日立製作所社製) を用いて測定することにより行った。
シアン ---------４８０ｎｍ
マゼンタ--------６８０ｎｍ
イエロー--------５８０ｎｍ
【００７５】
発色性の評価は、定着温度１５５℃で、普通紙上にベタ画像を形成し、ベタ画像部で、入射測定角が６０／６０の条件で、白色光を照射し、トナー付着量が０．６〜０．７ｍｇ／ｃｍの時の光沢度をグロスメーターにより測定した。光沢度２０以上を高光沢とする。
【００７６】
（２）帯電・現像性（帯電量・転写効率・画像濃度とカブリ）
（帯電量）
実施例１〜９および比較例１〜３により、得られたトナーの帯電量を測定した。本発明のトナーを用いた各色の現像剤は−１５から−２０μＣ／ｇの帯電量を持っており顔料による差はほとんど無かった。一方、比較例１のトナーは−１４μＣ／ｇであり、比較例２のトナーは−１５μＣ／ｇ、比較例３のトナーは−１４μＣ／ｇであった。
【００７７】
（転写効率）
感光体から中間転写体への転写効率１の測定には、感光体上のトナー像を透明な粘着テープで採取し、その画像をカラー反射濃度計で測定する。次に、再度トナー像を作製し、トナー像を中間転写体へ転写し同様に粘着テープで採取しその画像濃度を測定した。転写効率は以下の式に従い算出する。
【００７８】
転写効率１＝（中間転写体から採取したトナー画像濃度)/( 感光体から採取したトナー画像濃度)
【００７９】
同様に中間転写体から転写材への転写効率は以下の式に従い算出する。
【００８０】
転写効率２＝ (転写材から採取したトナー画像濃度)/( 中間転写体から採取したトナー画像濃度)
【００８１】
最終転写効率は以下の式に従い算出する。
【００８２】
最終転写効率= 転写効率１×転写効率２
【００８３】
（画像濃度とカブリ）
ＯＨＰ透過性および発色性評価の場合と同様の条件で、普通紙上に画像形成を行い、カラー反射濃度計(Color reflection densitometer）「Ｘ−ｒｉｔｅ ４０４Ａ」（Ｘ−ｒｉｔｅ社製）で、画像濃度を測定した。また、非画像部におけるカブリの有無は目視により確認した。
【００８４】
（３）定着性
（耐オフセット性）
富士ゼロックス社製「Ａ-Color」の改造機により、オフセット温度を測定し、以下の基準で耐オフセット性を判断した。
オフセット温度１５０℃未満..................×
オフセット温度１５０℃以上１８０℃未満......△
オフセット温度１８０℃以上..................○
【００８５】
（定着画像強度）
ＯＨＰ透過性および発色性評価の場合と同様の条件で、普通紙上に画像形成を行い、以下の基準で定着画像強度を判断した。
良好----ロール温度１８０℃で定着した画像をしごいてトナーの剥離無し
劣る----画像をしごくとトナーの剥離あり
【００８６】
（４）その他
また、トナー５ｇを４５℃，５０％ＲＨのチャンバーに１７時間放置した後、室温に戻し、このトナーを２ｇ採って、目開き４５μｍのメッシュに投入し、一定の条件で振動させ、メッシュ上に残ったトナーの重量を測定し、重量比を算出する（熱ブロッキング指数）という方法でトナーの熱ブロッキング性を評価したところ、本発明のトナーは、熱ブロッキング指数が６％未満と凝集が少なく、保存時の安定性にも優れていた。さらに、本発明のトナーを用いて得られた画像は高解像度の良好なものであり、転写材へのオフセットも無かった。さらに、３万枚連続の複写を行ったが３万枚後の画像は初期と変化のない良好なものであった。さらに高温高湿で画像評価を行ったが、画像乱れはまったくなかった。
一方、比較例１のトナーは、熱ブロッキング指数は８．４％と高く保存安定性にも劣り、得られた画像は高解像度の良好なものであるが、３万枚連続の複写を行った場合の３万枚後の画像は初期に比べ、やや画質が低下した。また、比較例２のトナーは、高温高湿下での画像かぶりが観察された。
【００８７】
以上の実施例から、本発明のトナーは、一成分現像剤としても、また、二成分現像剤としても使用可能であり、また、溶解懸濁法で作製したか、混練粉砕法で作製したかにかかわらず、トナー定着後の光透過率が８５％以上とＯＨＰ透過性に優れ、また、高い光沢度を有し発色性にも優れていることが分かる。また、現像剤の帯電量も、−１５から−２０μＣ／ｇと十分で、感光体１から中間転写体４への各色の転写効率は９８〜９９％、中間転写体４から転写材１０への転写効率は９８〜９９％、総合的には９６〜９８％の高い転写効率を有し、また、高現像濃度でカブリも少なく、帯電・現像特性に優れていることが分かる。
また、非線状の樹脂を含有する結着樹脂を用いた場合にも、同様にＯＨＰ透過性・発色性に優れていると同時に、結着樹脂の性能が如何なく発揮され、１８０℃という高温までオフセットを起こさず、定着性に優れ、画像定着強度にも優れていることが分かる。
さらに、本発明のトナーにおいては、保存安定性や環境依存性といった諸特性が損なわれていないことが分かる。
【００８８】
一方、シナージストと高分子分散剤のいずれをも用いない場合は、ＯＨＰ画像は、中間調が暗い画像となり、透明性に劣ることが分かる。それだけでなく、画像のホットオフセットは１４５℃で発生し、オイルレスでの定着性は不十分であることが分かる（比較例１）。高分子分散剤は用いているが、シナージストを用いない場合は、ベタ部のＯＨＰ発色は十分であるが、低画像濃度部での発色が不十分であることが分かる（比較例２、３）。
【００８９】
【発明の効果】
以上述べてきたように、本発明によれば、色材の分散性が良好で、透明性、発色性に優れ、安定した帯電性、現像性を有する静電潜像現像用トナーを提供することができる。
また、特に、架橋構造を有する非線状樹脂を結着樹脂として用いた場合にも、色材の分散性を安定化することができ、定着性に優れると同時に、透明性、発色性、帯電性、および現像性に優れ、カラー画像の形成に特に適した静電潜像現像用トナーを提供することができる。すなわち、シアン、マゼンタ、イエロー、ブラックの各色のトナーを重ねあわせても良好な色調の再現を可能とし、理想的な減色混合法によるあらゆる色調の実現が可能となった。
【図面の簡単な説明】
【図１】 ワックスのＤＳＣ吸熱曲線を示す模式図である。
【図２】 トナー粒子の断面を示す模式図である。
【図３】 本発明の画像形成方法に使用可能なカラー画像形成装置の一例を示す概略図である。
【図４】 本発明の画像形成方法に使用可能な非磁性一成分現像ユニットの構造を示す概略図である。
【符号の説明】
１ 感光体( 静電潜像担持体) 、
２ コロナ帯電器、
３ 露光装置
４ 中間転写体、
５ 四色現像器(5a,5b,5c,5d)
６ 転写帯電器、
７ クリーナー
８ 加熱ローラ
９ 加圧ローラ
１０ 転写材
１１ トナー溜め、
１２ 供給ロール、
１３ シール材
１４ 現像ロール、
１５ 規制ブレード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic latent image developing toner used in an electrophotographic process or the like, a method for producing the same, an electrostatic latent image developer, and an image forming method.
[0002]
[Prior art]
In recent years, demand for color image formation by electrophotography such as color copying has increased, and color copiers and the like have been put into practical use. In order to form these color images, it is necessary to superimpose several types of toner layers of different colors on the same support. Therefore, in the color image forming method by the electrophotographic method, the fixing characteristics that the color toner should have are extremely high. is important. That is, the fixed color toner needs to suppress irregular reflection by toner particles as much as possible and to exhibit appropriate glossiness. In addition, it should be a color toner having transparency that does not interfere with the color development of the toner layers of different tones under the toner layer and having a wide color reproducibility.
[0003]
In particular, quality requirements for full-color copy images have become increasingly sophisticated in recent years, and above all, demands for toner transparency have become higher, such as OHP images that require transparency equivalent to printing. Although it has been found that the transparency of the toner can be improved by improving the dispersibility of the color material in the toner, it has been difficult to sufficiently disperse the color material.
For example, Japanese Patent Application Laid-Open No. 61-117565 and Japanese Patent Application Laid-Open No. 61-156054 disclose a method in which a binder resin, a color material, and a charge control agent are dissolved in a solvent in advance and the solvent is removed to obtain a toner. However, the pigment dispersibility of the toners obtained by these methods was not satisfactory. Such poor dispersion of the pigments deteriorates not only the transparency of the toner but also other toner characteristics. Specifically, a pigment having a polarity such as carbon black is unevenly distributed on the toner surface, which causes a problem that toner charging characteristics, electrostatic developability and transferability are remarkably deteriorated. In addition, even if other organic pigments are used, the effect of the pigment type is strong and the chargeability of the toner is significantly different. This makes it difficult to design the charging of the developer, and as a result, a high-quality color image cannot be obtained.
[0004]
Various studies have been made to improve the dispersibility of the coloring material. For example, Japanese Patent Application Laid-Open No. 7-152202 proposes a method in which polyester is dissolved and then granulated in an aqueous phase containing an inorganic dispersant. JP-A-7-168395 proposes tricalcium phosphate and hydroxyapatite having a particle size of 0.7 to 5 μm as inorganic dispersants to be used. These are proposals relating to a dissolution suspension method in which an oil phase solution in which a toner component is dissolved is granulated in an aqueous phase, and after removing the solvent, the powder is pulverized. The inorganic dispersant here is used in the aqueous phase. It is added to stabilize the dispersion of the oil phase droplets. Certainly, if the dispersion of the oil phase droplets is stabilized, the content of the color material between the oil phase droplets, that is, between the toner particles becomes uniform, but the color material in the individual toner particles becomes uniform. The dispersibility of the toner is not improved at all, and the toners obtained by these methods do not provide satisfactory performance in all aspects of transparency, chargeability and developability.
[0005]
In particular, in a color image forming method, the color balance of at least three color toners, preferably four color toners, must be harmonized, and the fixing characteristics and color reproducibility of only one color can be discussed. meaningless. It is necessary to design and select a resin in consideration of the superposition and balance of four-color toners.
In other words, if there are three colors of cyan, yellow, and magenta, it should be possible to reproduce almost all colors by the subtractive color mixing method. Therefore, the current full-color copying machine is configured to use three colors in an overlapping manner. Yes. This should ideally achieve any color tone with any density distribution, but in reality, there are points to be improved such as the spectral reflectance characteristics of the toner, the color mixing characteristics when the toners are superimposed, and the reduction in saturation. Have.
[0006]
[Problems to be solved by the invention]
The first object of the present invention is to provide a toner for developing an electrostatic latent image, which has good dispersibility of the color material, excellent transparency and color developability, and can obtain stable chargeability and developability, and a method for producing the same. It is to provide.
The second object of the present invention is to provide a toner for developing an electrostatic latent image, which can achieve both high fixability and transparency / color development, and is suitable for forming a color image, and a method for producing the same. is there.
A third object of the present invention is to provide an electrostatic latent image developer and an image forming method using the electrostatic latent image developing toner of the present invention.
[0007]
[Means for Solving the Problems]
  As a result of intensive studies on the method of dispersing the color material in the toner, the present inventors have used a synergist and a polymer dispersant in combination, so that the binder that is a color material, a polymer dispersant, or a dispersion medium can be used. The inventors have found that good dispersibility can be obtained regardless of the type of resin, and have completed the present invention.
  That is, the electrostatic latent image developing toner of the present invention comprises at least a binder resin and a color material.It is obtained by suspending and granulating an oil phase in which a toner component containing at least a binder resin and a coloring material is dissolved or dispersed in an organic solvent.In the electrostatic latent image developing toner, the color material is dispersed by a polymer dispersant and a synergist having a common skeleton with the color material and a polar functional group that interacts with the polymer dispersant. And the shape factor MLS2 defined by the following formula is in the range of 100 to 140.
      MLS2 = ( Absolute maximum length of toner particles ) ² / ( Projected area of toner particles ) × π × 1/4 × 100
[0008]
In general, the polymer dispersant has a part (anchor part) that expresses interaction with the pigment in the molecule and a part (tail or loop) that solvates and spreads from the pigment surface into the solvent. The pigment is dispersed in the solvent by both actions. Therefore, in order to increase the dispersibility of the pigment, it is first necessary to increase the interaction between the polymer dispersant and the pigment. For example, a dispersant having a basic functional group in acidic carbon black. It is effective to combine the pigment dispersant and the pigment surface so as to cause an acid-base interaction. However, pigments with a small amount of acid or base, such as quinacridone pigments, are difficult to disperse due to their small interaction with the dispersant and difficult to stabilize.
[0009]
In the present invention, a synergist means a compound that has a strong interaction with a pigment and also has a strong interaction with a polymer dispersant. In the present invention, this synergist is used in combination with a polymer dispersant. Thus, it is considered that the synergist mediates between the pigment and the polymer dispersant, and thus even a pigment having a small amount of acid or base can be effectively dispersed. For example, for quinacridone pigments, when dimethylaminoethylquinacridone, which is a derivative of quinacridone pigment, is added as a synergist, dimethylaminoethylquinacridone has a common skeleton with the quinacridone pigment and is strongly adsorbed on the pigment surface. The interaction between the synergist and the pigment is considered to be van der Waals force, but it is presumed that strong and practical adsorption can be achieved because it acts on the entire flat surface of the dye skeleton. Furthermore, since dimethylaminoethylquinacridone has a tertiary amino group, which is a basic functional group, if the dispersant has an acidic functional group, the pigment will be indirectly adsorbed to the resin via the synergist, and the pigment will be dispersed. It can be stabilized.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[0011]
As the binder resin of the present invention, polyester resin, styrene resin, acrylic resin, styrene / acrylic resin, silicone resin, epoxy resin, diene resin, phenol resin, terpene resin, coumarin resin, amide resin, amideimide resin, butyral resin Known binder resins such as urethane resin and ethylene / vinyl acetate resin can be used.
[0012]
Among these, a polyester resin having sufficient flexibility even when the molecular weight is reduced is preferable in that it melts sharply at the time of fixing and the surface of the image can be smoothed, and another resin is used in combination with the polyester resin. May be.
[0013]
The alcohol component of the polyester resin includes polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2-bis (4-hydroxyphenyl) Propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) Propane, polyoxypropylene (2,0) -polyoxyethylene (2,0) -2,2-bis (4- Hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane and other diols, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol Coal, propylene glycol, dipropylene glycol, isopentyl glycol, dipropylene glycol, isopentyl glycol, hydrogenated bisphenol A, 1,3-butanediol, 1,4-butane All, neopentyl glycol, xylylene glycol, 1,4-cyclohexanedimethanol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, bis- (β-hydroxyethyl) terephthalate, tris- (β-hydroxyethyl) isocyania Examples thereof include nurate and 2,2,4-trimethylolpentane-1,3-diol.
[0014]
On the other hand, as the acid component, malonic acid, succinic acid, glutaric acid, dimer acid, phthalic acid, isophthalic acid, terephthalic acid, isophthalic acid dimethyl ester, terephthalic acid dimethyl ester, terephthalic acid monomethyl ester, tetrahydroterephthalic acid, methyltetrahydrophthale Acid, hexahydrophthalic acid, dimethyltetrahydrophthalic acid, endomethylenehexahydrophthalic acid, naphthalenetetracarboxylic acid, diphenolic acid, trimellitic acid, pyromellitic acid, trimesic acid, cyclopentanedicarboxylic acid, 3,3 ', 4 , 4'-benzophenone tetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 2,2-bis- (4-carboxyphenyl) propane, trimellitic anhydride and 4,4-diaminophenylmethane The resulting diimidecarboxylic acid, tris- (β-carboxy Chill) isocyanurate, isocyanurate ring-containing polyimide carboxylic acid, tolylene diisocyanate, xylylene diisocyanate or isophorone diisocyanate trimerization reaction product and trimellitic anhydride-containing polyimide carboxylic acid, etc. Or two or more are used.
[0015]
In the present invention, among polyester resins, in terms of stability such as fixing strength and offset resistance, in particular, a three-dimensional crosslinking having a trivalent or higher monomer or other crosslinking agent as a constituent monomer in a part of the resin. A polyester resin blended with the non-linear polyester subjected to the above is preferred.
In general, the cross-linked nonlinear polyester has a weak cross-linked structure, but the whole polymer is constituted as a single three-dimensional polymer, and when used as a binder resin, the temperature is higher than a mixture of simple linear polymers. It is excellent in preventing hot offset on the side, but if the crosslinking density is increased too much by using a trivalent or higher monomer as a crosslinking component, the elasticity of the polyester increases and the melting rate decreases, so it melts sharply. Compared with a normal linear polymer, the smoothness and glossiness after fixing are inferior, and the color reproducibility becomes poor.
However, by blending an appropriate amount of this with linear polyester, it is possible to suppress a decrease in melting rate to such an extent that the smoothness and glossiness of the fixed image are not substantially impaired.
[0016]
As the non-linear polyester subjected to three-dimensional crosslinking, specifically, a diol component and a dicarboxylic acid component are capable of cross-linking a trivalent or higher polyvalent carboxylic acid component regularly in a linear polymer chain. A polyester resin having a weak cross-linked structure introduced as a monomer component is preferably used.
Specific examples of trivalent or higher polyvalent carboxylic acids and polyhydric alcohols include trivalent carboxylic acids such as trimellitic anhydride, 2,5,7-naphthalene tricarboxylic acid, or derivatives thereof, glycerol, trimethylol. Examples thereof include trivalent alcohols such as propane. In addition, it is preferable to use a monomer having a side chain having 2 to 30 carbon atoms such as dodecenyl succinic acid because the softening point can be adjusted.
[0017]
The blend ratio of the non-linear polyester is preferably 1 to 40%, more preferably 10 to 30%. If the non-linear polyester exceeds 40%, the minimum fixing temperature increases, and the color developability and OHP permeability are inferior. If the non-linear polyester is less than 1%, sufficient offset resistance cannot be obtained.
The softening point of the resin after blending is preferably 90 ° C. or more and 120 ° C. or less, and in terms of gloss, the difference in softening point between the linear polyester resin and the non-linear polyester resin is 20 ° C. or less. The optimum temperature is 10 ° C or lower. When the softening point is less than 90 ° C., the storage stability of the toner is poor, and for example, the toner may block in a storage state of 80 RH at 45 ° C. When the softening point exceeds 120 ° C., the minimum fixing temperature of the toner rises, and further, the color developability and the OHP permeability are reduced, resulting in a dull color. Further, the toner particle production may be deteriorated.
Here, the softening point is 1 cm using a descending flow tester (Shimadzu Corporation).^ThreeWhile heating the sample at a heating rate of 6 ° C./min, 30 kg / cm by the plunger²A nozzle having a diameter of 1 mm and a length of 1 mm is pushed out, whereby a plunger descending amount vs. temperature curve is drawn, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 ( Temperature at which half of the resin flows out).
The glass transition temperature of the resin after blending is preferably 40 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 70 ° C. or lower. Furthermore, since the glass transition temperature difference between the linear polyester and the non-linear polyester also affects the toner characteristics, the glass transition temperature difference between the linear polyester resin and the non-linear polyester resin is 20 ° C. or less, preferably 10 ° C. or less. It is best to do. When the glass transition temperature is lower than 40 ° C., the toner storage stability is deteriorated. When the glass transition temperature exceeds 80 ° C., the minimum fixing temperature may be increased, and the toner particle production may be deteriorated.
[0018]
Further, for reasons such as transparency and storage stability, the weight molecular weight by GPC of the resin after blending is preferably 2000 to 50000, and more preferably 8000 to 20000. Furthermore, the sum of the acid value and the hydroxyl value is preferably 5 KOH mg / g or more and 100 KOH mg / g or less, more preferably an acid value of 25 KOH mg / g or less and a hydroxyl value of 25 KOH mg / g or less. Those having an acid value and a hydroxyl value exceeding these ranges are easily affected by the environment under high temperature and high humidity and low temperature and low humidity, and are liable to cause image deterioration.
[0019]
In the present invention, known organic or inorganic pigments and dyes and oil-soluble dyes can be used as the colorant to be dispersed. CI Pigment Red 48: 1, CI Pigment Red 57: 1, CI Pigment Red 122, CI Pigment Yellow 17, CI Pigment Yellow 97, CI Pigment Yellow 12, CI Pigment Yellow 180, CI Pigment Yellow 185, CI Pigment Blue 15: 1, CI Pigment Blue 15: 3, Lamp Black (CI No. 77266), Rose Bengal (CI No. 45432), Carbon Black, Nigrosine Dye (CI No. 50415B), Metal Complex Dye, Metal Complex Dye Derivatives These A mixture etc. can be mentioned. Furthermore, various metal oxides such as silica, aluminum oxide, magnetite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, and magnesium oxide, and mixtures thereof can be used.
These coloring materials need to be contained in a sufficient ratio to form a visible image having a sufficient density, and generally depend on the toner particle size and the development amount, but generally with respect to 100 parts by weight of the toner. It is appropriate to mix | blend in the ratio of about 1-100 weight part.
[0020]
The synergist of the present invention is not particularly limited as long as it has a strong interaction with the colorant and also has a strong interaction with the polymer dispersant. A pigment or dye derivative or precursor having a common skeleton with the material is preferred.
Moreover, it is preferable to have a polar functional group having high affinity with the polymer dispersant in that the interaction with the polymer dispersant is strong. The interaction between the synergist and the polymer dispersant may be a hydrogen bond interaction or an acid-base interaction. In order to enhance the interaction by hydrogen bonding, the synergist preferably has a functional group such as a hydroxyl group or an amide group. Further, in order to enhance the acid-base interaction, when the polymer dispersant has an acidic functional group, those having a basic functional group such as an amino group are preferable, and the polymer dispersant has a basic functional group. When it has, what has acidic functional groups, such as a carboxyl group and a sulfonate group, is preferable.
For example, examples of the quinacridone pigment synergists include dimethylaminoethyl quinacridone and dihydroxyquinacridone, and examples of the anthraquinone dye synergists include anthraquinone sulfonic acid derivatives and anthraquinone carboxylic acid derivatives.
[0021]
A known polymer dispersant can be used as the polymer dispersant of the present invention. Specifically, it is preferable to use a resin such as a polyester resin, a polycaprolactone resin, an acrylic resin, an unsaturated polyester resin, a photosensitive monomer having an (meth) acryloyl group, or an oligomer as a dispersant. Furthermore, poly (meth) acrylic acid ester or a hydrolyzate thereof, polyvinyl acetate or a partially saponified product thereof, polyvinyl phenol, phenol novolac, polystyrene, polyvinyl butyral, polychloroprene, polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene. , Polyvinylpyrrolidone, copolymer of styrene and maleic anhydride or half ester thereof, and further selected from copolymerizable monomers such as (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, (meth) acrylonitrile, etc. The polymer obtained can also be used suitably.
In consideration of the charging characteristics of the toner and the dispersibility in the binder resin, it is preferable to use the same type of resin as the binder resin. If the binder resin is a polyester resin, the polymer dispersant is also a polyester resin or a polycaprolactone resin. Is preferable.
Specific examples of the lactone compound constituting the polycaprolactone resin include ε-caprolactone, σ-valerolactone, β-methyl-σ-valerolactone, 4-methylcaprolactone, 2-methylcaprolactone, β-propiolactone, γ-propiobutyl lactone and the like can be mentioned. These may be used alone or as a mixture of two or more.
[0022]
The amount of the synergist and polymer dispersant used is 0.1 to 100 parts by weight, preferably 1 to 50 parts by weight, per 100 parts by weight of the color material. If the amount is less than 0.1 part by weight, the desired colorant dispersibility cannot be obtained. When the amount exceeds 100 parts by weight, the charging characteristics of the toner, particularly the charging characteristics under high temperature and high humidity, are greatly deteriorated.
[0023]
In the present invention, if necessary, other components such as a charge control agent and a release agent may be added to the toner.
Examples of the charge control agent of the present invention include metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing bisazo dyes, tetraphenylborate derivatives, A compound selected from the group consisting of a quaternary ammonium salt and an alkylpyridinium salt, and a proper combination thereof can be preferably used.
The amount of these charge control agents added to the toner is generally from 0.1% to 10% by weight, more preferably from 0.5 to 8% by weight. This is because if the amount is less than 0.1% by weight, the charge control effect is insufficient, and if it exceeds 10% by weight, the toner resistance is excessively lowered and is difficult to use.
[0024]
Furthermore, a metal soap, an inorganic or organic metal salt can be used in combination with the charge control agent. Such metal soaps include aluminum tristearate, aluminum distearate, barium, calcium, lead and zinc stearate, or cobalt, manganese, lead and zinc linolenate, aluminum, calcium, cobalt octanoic acid Salts, calcium and cobalt oleates, zinc palmitate, calcium, cobalt, manganese, lead and zinc naphthenates, calcium, cobalt, manganese lead and zinc resins and the like can be used. In addition, as the inorganic and organic metal salt, for example, the cationic component in the metal salt is selected from the group consisting of metals of Group 1, Group 2, and Group 3 of the periodic table, and the anionic nature of the acid Is a salt selected from the group consisting of halogens, carbonates, acetates, sulfates, borates, nitrates, and phosphates. These charge control or cleaning aids are generally in the range of 0.1 wt% to 10 wt%, more preferably 0.1 wt% to 5 wt% with respect to the toner weight. This is because if the amount is less than 0.1% by weight, the desired effect is insufficient, and if it exceeds 10% by weight, the toner powder fluidity is lowered and it is difficult to use.
[0025]
Various waxes can be added as the release agent of the present invention. Specifically, the following wax can be added. Waxes and natural waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin and microcrystalline. And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, and chlorinated hydrocarbons, esters and ketones Synthetic waxes such as ether can also be used. Still other mold release agents include homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate (eg, n-stearyl acrylate-ethyl methacrylate copolymer). Examples thereof include crystalline polymers having a long alkyl group in the side chain, but more preferred are petroleum waxes such as paraffin wax and microcrystalline wax, or synthetic waxes.
[0026]
FIG. 1 is a schematic diagram showing a DSC (differential scanning calorimeter) endothermic curve of wax. DSC (Differential Scanning Calorimeter) endothermic curve is measured according to ASTM D3418-8. In this DSC endothermic curve, the peak top of the endothermic main peak indicates the melting point, and the end point of the endothermic main peak deviates from the baseline. Indicates the endothermic start temperature (tangential separation temperature).
As the wax used in the present invention, a melting point which is an endothermic main peak in a DSC (differential scanning calorimeter) endothermic curve measured according to ASTM D3418-8 is preferably 50 ° C. or higher and 120 ° C. or lower. More preferred are those having a temperature of from 90 ° C. to 90 ° C. Such a wax effectively acts as a release agent between the fixing roller and the toner interface, thereby preventing high-temperature offset without applying a release material such as oil to the fixing roller. On the other hand, when the melting point exceeds 120 ° C., the effect of releasability is not sufficient. On the other hand, if the melting point is lower than 50 ° C., the storage stability of the toner under high temperature and high humidity may be insufficient, or the developability of the toner may be deteriorated during long-term use.
Further, a low softening point material having a DSC curve endothermic start temperature of 40 ° C. or higher is more preferable. When the endothermic start temperature is lower than 40 ° C., the toner has insufficient blocking resistance and storage stability, and there may be a problem in image storage stability during overlay.
[0027]
When a release agent such as wax is added, it has been confirmed that the dispersibility of the wax in the toner affects the permeability. If the dispersibility of the wax in the toner is low, the transparency of the image after fixing is slightly lowered when a transparency film is used as the recording material. In other words, if the dispersion unit of the wax in the toner is reduced to a unit that does not affect the permeability, the problem of the decrease in the permeability is eliminated regardless of the degree of the crystallinity of the wax. Specifically, the average dispersion diameter in the toner may be 3 μm or less, more preferably 1 μm or less. For this purpose, it is necessary to use the wax used at the time of toner preparation in advance with an average diameter reduced to 3 μm or less, more preferably 1 μm or less. If the average diameter of the wax exceeds 3 μm, the transparency of the image after fixing is deteriorated when a transparency film is used.
The average particle size of the wax can be measured as follows. The toner particles are solidified with a binder resin such as epoxy, sliced with a microtome to a thickness of about 1000 angstroms, and observed with a transmission light microscope, phase-separated wax particles can be seen. In the present invention, in order to minimize the error due to the grain section, 10 points were measured, and the average of 5 points having a large value was taken as the average particle size.
In order to refine the release agent, for example, the emulsification described in Reaction Engineering Study Group Report-1 “Emulsification / Dispersion Technology and Particle Size Control of Polymer Fine Particles, Chapter 3” published in March 1995 The fine particles may be formed by any conventionally known method such as a method using a dispersing device. Also, use a suitable solvent that is compatible with the solvent used at the time of toner preparation and does not dissolve the release agent at room temperature. After adding the release agent to the solvent and dissolving it with heating, it is gradually cooled to room temperature and released. Method of depositing fine particles of mold agent (dissolving precipitation method) or heating and evaporating release agent in inert gas such as helium to produce particles in gas phase, and then attaching these particles to cooled film etc. It is more effective to combine the method of dispersing in a solvent after recovery (vapor phase evaporation method) with the mechanical pulverization method using the media or the like.
[0028]
The amount of the wax added is 0.1% by weight or more and 40% by weight with respect to the toner in terms of maintaining the offset resistance, maintaining the developability and transferability of the toner, and preventing filming on the photoreceptor and the charge imparting member. It is preferable to set it as the weight% or less.
FIG. 2 is a schematic diagram showing a cross section of the toner particles. As shown in FIG. 2, the wax particles are not only contained in the toner, but a part of the wax particles is exposed on the toner surface. Here, the toner surface is d in FIG.₂The part represented by d₂Is 0.2 μm or less. When the addition amount of the wax is 0.1% by weight or more and 40% by weight or less, the presence ratio of the wax exposed on the toner surface is controlled to be in the range of 1% by weight or more and 10% by weight or less, so that good resistance to resistance is obtained. The offset property, the developing property of the toner and the transfer property are maintained, and filming to the photosensitive member and the charge imparting member can be prevented. When the amount of wax on the toner surface is 1% by weight or less, sufficient offset resistance cannot be obtained.
The ratio of the wax present on the toner surface can be measured by elemental analysis of the surface by ESCA. The elemental analysis of the surface by ESCA is to determine the elemental composition ratio of the surface by measuring the element on the surface of the toner, then to obtain the molecular formula of each compound contained in the toner, and from the elemental composition ratio of the surface measured by ESCA This is a method for calculating the content of each compound present in.
[0029]
Next, a method for producing the electrostatic latent image developing toner of the present invention will be described.
In the method for producing a toner for developing an electrostatic latent image of the present invention, there is no particular limitation as long as the color material as a toner component is previously dispersed by a synergist and a dispersant. However, it is preferable to produce the toner particles by a so-called dissolution suspension method from the viewpoint of easy control of the shape of the toner particles.
[0030]
Hereinafter, the method for producing the toner for developing an electrostatic latent image of the present invention will be described by taking the dissolution suspension method as an example. In the dissolution suspension method, first, an oil phase is prepared by dissolving or dispersing the toner component including at least the binder resin and the color material in an organic solvent.
The organic solvent that can be used depends on the type of binder resin, but in general, hydrocarbons such as toluene, xylene, hexane, halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, ethanol, butanol, benzyl alcohol ether, tetrahydrofuran Such alcohols or ethers, esters such as methyl acetate, ethyl acetate, butyl acetate and isopropyl acetate, and ketones such as acetone, methyl ethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexane are used. These solvents need to dissolve the binder resin, but the coloring material and other additives need not be dissolved. The weight ratio of the toner components such as the binder resin and color material used in the oil phase and the solvent is preferably 10/90 to 80/20 in terms of easy granulation or the final toner yield.
[0031]
In the present invention, before adjusting the oil phase, a color material dispersion is prepared in which a color material is previously dispersed with a synergist and a dispersant, and this is mixed with a binder resin or the like.
In producing the color material dispersion, first, a synergist and a dispersant are attached to the color material. The coloring material is attached using a normal stirring device. Specifically, for example, a coloring material, a synergist, and a dispersing agent are put into a suitable container equipped with granular media such as an attritor, a ball mill, a sand mill, and a vibration mill, and the container is placed in a preferable temperature range, for example, 20 ° C. to 160 ° C. A method of stirring while maintaining the temperature range of ° C. can be used, and as the granular media, steel such as stainless steel and carbon steel, alumina, zirconia, silica and the like are preferably used. With these stirring devices, the color materials are aggregated, and the color materials are dispersed until the average particle size of the color materials is about 0.5 μm or less, preferably about 0.3 μm or less. And a dispersing agent are adhered to the coloring material. This is diluted with a solvent to obtain a colorant dispersion.
[0032]
In the present invention, it is preferable to disperse the coloring material again by high-speed shearing or the like so that the coloring material does not aggregate when the coloring material dispersion and the binder resin are mixed. Dispersion can be performed by a disperser equipped with a high-speed blade rotating type or a forced interval passing type high-speed shearing mechanism such as various homomixers, homogenizers, colloid mills, ultra turraxes, and Claire mills. When adjusting the oil phase liquid, it is preferable to disperse the coloring material in the oil phase liquid to 1 μm or less, desirably 0.5 μm or less, and more desirably about 0.3 μm or less.
[0033]
Next, these oil phase components are suspended and granulated so as to have a predetermined particle size in the aqueous phase.
The main medium of the aqueous phase is water, but if necessary, the following inorganic or organic dispersion stabilizer may be added. These dispersion stabilizers stabilize the oil phase droplets by forming a hydrophilic colloid. Examples of inorganic dispersion stabilizers include calcium carbonate, magnesium carbonate, barium carbonate, tricalcium phosphate, hydroxyapatite, silicate diatomaceous earth, and clay. These inorganic dispersion stabilizers preferably have a particle size of 1 to 2 μm, more preferably 0.1 μm or less, and are used after being pulverized to a desired particle size by a wet disperser such as a ball mill, sand mill, or attrier. desirable. When the particle size of these inorganic dispersion stabilizers exceeds 2 μm, the granulated toner has a wide particle size distribution and cannot be used as a toner. Specific examples of organic dispersion stabilizers that may be used in combination with these inorganic dispersion stabilizers include gelatin, gelatin derivatives (eg, acetylated gelatin, phthalated gelatin, succinated gelatin, etc.), albumin, Proteins such as casein, collodion, gum arabic, agar, alginic acid, cellulose derivatives (eg, alkyl esters of carboxymethyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose, etc.), synthetic polymers (eg, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, poly Acrylate, polymethacrylate, polymaleate, polystyrene sulfonate) and the like. These organic dispersion stabilizers may be used alone or in combination of two or more. The dispersion stabilizer is preferably used in the range of 0.001 to 5 parts by weight with respect to the main medium of the aqueous phase.
[0034]
A dispersion stabilizer may be used in combination with the aqueous phase. Various surfactants are easy to use as the dispersion stabilizing aid. Surfactants include ionic and nonionic surfactants. Specifically, alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonic acid of higher fatty acid ester, etc. can be used as an anionic surfactant. . As the cationic activator, primary to tertiary amine salts, quaternary ammonium salts and the like can be used. Nonionic activators include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester , Fatty acid alkylolamide and the like can be used. These dispersion stabilizing aids may be used alone or in combination of two or more. The dispersion stabilizing aid is preferably used in the range of 0.001 to 5 parts by weight with respect to the main medium of the aqueous phase.
[0035]
The mixing of the oil phase and the aqueous phase varies depending on the final toner particle size and production apparatus, but is usually preferably 10/90 to 90/10 in weight ratio.
The granulation of the oil phase in the aqueous phase is preferably performed under high speed shearing. In particular, when the toner particle size is in the range of 5 to 9 μm, it is necessary to pay attention to the selection of a disperser having a high-speed shearing mechanism to be used. Among them, various types of homomixers, homogenizers, colloid mills, ultra turraxes, Claire mills, and other high speed blade rotating type and forced interval passing type emulsifying dispersers are easy to use.
[0036]
The solvent is removed during or after the granulation process. The removal of the solvent may be performed at room temperature or may be performed under reduced pressure. In order to carry out at normal temperature, it is necessary to apply a temperature that is lower than the boiling point of the solvent and takes into account the Tg of the resin. If the Tg of the resin is greatly exceeded, undesirable toner coalescence may occur. Usually, it is convenient to stir at around 40 ° C. for 3 to 24 hours. When depressurizing, it is convenient to carry out at 20-150 mmHg.
[0037]
The obtained granulated product (slurry product) is preferably washed with an acid such as hydrochloric acid, nitric acid, formic acid, acetic acid or the like that makes the inorganic dispersion stabilizer water-soluble. Accordingly, it is necessary to remove the inorganic dispersion stabilizer remaining on the toner surface. In the toner in which the inorganic dispersion stabilizer or the organic dispersion stabilizer described above remains on the toner surface, the humidity dependency of the residual deposits deteriorates the charge dependency of the toner as a humidity. It is necessary to remove such a dispersion stabilizer as much as possible to minimize the influence on the charging property and powder flowability of the toner.
The acid or alkali-treated granulated product may be washed again with an alkaline water such as sodium hydroxide if necessary. Thereby, a part of the ionic substance on the surface of the toner insolubilized by being placed in an acidic atmosphere is solubilized and removed again, which is advantageous in chargeability and powder flowability. Such washing with acid or alkaline water has the effect of washing and removing the wax adhering to the toner surface. In addition to conditions such as pH at the time of washing, the number of times of washing, temperature at the time of washing, and the like, the use of a stirrer, an ultrasonic dispersing device, and the like is effective for carrying out the washing effectively. Thereafter, steps such as filtration, decantation, and centrifugation are performed as necessary, and after drying, the toner particles of the present invention can be obtained.
[0038]
The toner obtained by the production method of the present invention has an average colorant particle diameter in the toner of 0.7 μm or less, and more preferably in the range of 0.1 μm to 0.5 μm. When the average colorant particle diameter in the toner is controlled to 0.7 μm or less, it is possible to reproduce a good color tone even if several kinds of toners are overlapped. On the other hand, when it is larger than 0.7 μm, it means that there are many pigment particles that are not sufficiently dispersed, and this makes it impossible to obtain sufficient color reproducibility and OHP permeability. In addition, if the pigment particles in the toner are present as aggregates in a non-uniform state, the charge amount varies significantly between the toner particles, the charge amount becomes broad, and cyan, yellow, magenta, There is a significant difference in the charge amount between the black toners. In this case, the desired high-quality full-color image cannot be obtained.
Here, the average colorant particle diameter in the toner is the individual colorant particle dispersion diameter d in FIG.₁It is the value which took the 10-point average.
[0039]
As the shape of the toner of the present invention, a toner having a more spherical shape is preferable in terms of transfer efficiency. Specifically, a toner having a shape factor MLS2 in the range of 100 to 140 is preferable, and 100 to 120 is more preferable. preferable. A decrease in toner transfer efficiency is observed when MLS2 exceeds 140. In particular, when a full-color copier that develops and transfers multiple toner images is used, the amount of toner on the photoreceptor increases compared to conventional monochrome toner, and transfer efficiency is improved by using conventional amorphous toner. It is difficult to do. For this reason, in color image formation, it is difficult to uniformly transfer the four color toners, and when using an intermediate transfer body, problems are likely to occur in terms of color unevenness and color balance, and high-quality full-color images can be stably produced. It is not easy to output. Therefore, it is preferable to design a process by effectively using the low toner adhesion to the transfer member due to such a spherical toner shape. It is also possible to design a small and simple process that employs the cleaning-less and utilizes the high transfer efficiency characteristics of the toner.
[0040]
Here, MLS2 refers to a value obtained by calculation from the following equation.
MLS2 = (absolute maximum length of toner particles)²/ (Projection area of toner particles) × π × 1/4 × 100
The value of MLS2 is, for example, using “FE-SEM (S = 800)” manufactured by Hitachi, Ltd., and randomly sampling 100 toner images magnified to a magnification of 500 times, and the image information is obtained via the interface. It can be obtained by introducing into an image analysis apparatus “Luzex III” manufactured by Nireco and performing analysis.
[0041]
The shape of the toner can be changed from a spherical shape to an indefinite shape by controlling the difference in toner production conditions, in particular the formulation of the toner material and the process conditions for evaporating the solvent from the toner after granulation, In addition, it is possible to obtain a toner shape having minute irregularities, ridges, holes, and protrusions. In general, the toner produced by the kneading and pulverizing method has an indeterminate shape, MLS2 is about 140 to 160, and MLS2 of the toner produced by the dissolution suspension method is about 100 to 120. It is preferable that the toner is prepared by a dissolution suspension method capable of obtaining a more spherical toner.
[0042]
A known external additive may be added to the toner for developing an electrostatic latent image of the present invention in order to control fluidity and developability. As the external additive, various inorganic oxide fine particles such as silica, alumina, titania, cerium oxide and the like, hydrophobic particles as necessary, vinyl polymer, zinc stearate, and the like can be used. The amount of external addition is preferably in the range of 0.05 to 5 parts by weight with respect to the toner before addition.
[0043]
The electrostatic latent image developer of the present invention uses the above-mentioned toner for developing an electrostatic latent image, and can be used without limitation to a known dry electrostatic charge developing method. For example, limited to two-component development methods such as cascade method, magnetic brush method, microtoning method, one-component development method such as conductive one-component development method, insulating one-component development method, and non-magnetic one-component development method Can be used without
The electrostatic latent image developing toner of the present invention can be used as a two-component developer by combining with a carrier. In this case, it is preferable that the carrier has a resin coating layer. The electrostatic latent image developing toner of the present invention can be used as a one-component developer by replacing all or part of the black colorant with magnetic powder to become a magnetic one-component toner. As the magnetic powder, magnetite, ferrite, or a simple metal such as cobalt, iron, nickel, or an alloy thereof can be used.
[0044]
The image forming method of the present invention includes a latent image forming step for forming a latent image on a latent image carrier, a developing step for developing the latent image with a developer, and a toner formed on the latent image carrier. The image forming apparatus includes a transfer process for transferring an image to a transfer body and a fixing process for fixing a toner image on the transfer body.
In the step of developing the latent image using a developer, the developer is an electrostatic latent image developing toner containing at least a binder resin and a color material, and the color material is composed of a synergist and a polymer dispersant. There is no particular limitation as long as a developer using the electrostatic latent image developing toner dispersed is used. Each of these steps is a general step, and is described in, for example, Japanese Patent Laid-Open Nos. 56-40868 and 49-91231. The image forming method of the present invention can be carried out using an image forming apparatus such as a copier or a facsimile machine known per se.
[0045]
The image forming method of the present invention will be specifically described below together with the image forming apparatus.
FIG. 3 is a schematic view showing an example of a color image forming apparatus that can be used in the image forming method of the present invention. The color image forming apparatus shown in FIG. 3 includes an image forming unit, a heat fixing unit, and a cleaning unit. The image forming means includes a photosensitive member 1, a corona charger 2, an exposure device 3, an intermediate transfer member 4 in which an elastic layer 4a having a controlled electric resistance value is provided on a pipe-shaped conductive core 4b, cyan, magenta , Developing devices 5 a, 5 b, 5 c, 5 d loaded with yellow and black developers, and a transfer charger 6. As the photosensitive member 1, a photosensitive drum or belt having a photoconductive insulating layer such as a-Se, OPC, a-Si, or ZnO is used, and among them, an OPC or a-Si photosensitive member is preferably used. As the corona charger 2, a contact type using a roller or a magnetic brush is used in addition to a non-contact type charger with respect to the photosensitive member. The heat fixing unit includes a pair of heat roll fixing devices including a heating roller 8 and a pressure roller 9 incorporating a heating element such as a halogen heater. A detachable cleaner 7 is provided as a cleaning means.
[0046]
When a color image is formed using the apparatus shown in FIG. 3, the photosensitive member 1 charged by the corona charger 2 is exposed by the exposure device 3 to form an electrostatic latent image on the photosensitive member 1. . This electrostatic latent image is developed in order by developing devices 5 a, 5 b, 5 c, 5 d loaded with cyan, magenta, yellow, and black developers, and the developed images are transferred to the intermediate transfer body 4. The toner image on the intermediate transfer body 4 is applied with a bias charge having a polarity opposite to the frictional charge of the toner by the transfer charger 6 and transferred to the surface of the transfer material 10. The toner image on the transfer material 10 is fixed on the transfer material 10 by passing the transfer material 10 between the heating roller 8 and an elastic pressure roller 9 pressed by a pressing force to form a color image. Is done.
[0047]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples and comparative examples. In Examples and Comparative Examples, “parts” means “parts by weight”.
[0048]
[Binder resin production example]
(Preparation of binder resin A (linear polyester))
1050 parts of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane
520 parts of fumaric acid
Hydroquinone (polymerization inhibitor) 1 part
The above-mentioned materials shown in Table 1 were put together with an esterification catalyst (dibutyltin oxide) into a glass 3-liter four-necked flask equipped with a stainless steel stirring rod, a flow-down condenser, and a nitrogen inlet tube, and in an electric heating mantle heater. The reaction proceeded with stirring under a nitrogen stream, the first half at 230 ° C. and normal pressure, and the second half at 200 ° C. under reduced pressure. Table 1 shows the physical property values of the obtained binder resin A (linear polyester).
(Preparation of binder resins B to E)
The materials shown in Table 1 were reacted in the same manner as the binder resin A (linear polyester) to prepare binder resins B to D. Table 1 shows the physical property values of the obtained binder resins B to D. Binder resin D is linear polyester, and binder resins B and C are cross-linked polyester.
[0049]
[Table 1]

[0050]
Example 1
[0051]
(A) Adjustment of colorant dispersion
Glass beads were added to a dispersion having the following material composition and mounted on a sand mill disperser. While cooling around the dispersion vessel, the mixture was dispersed for 3 hours in a high-speed stirring mode, and then diluted with ethyl acetate to prepare a color material dispersion having a color material concentration of 10% by weight.
Magenta pigment: (C.I.Pigment Red 122, ECR186Y; manufactured by Dainichi Seika Co., Ltd.) 88 parts
Synergist: Dimethylaminoethylquinacridone 2 parts
Polymer dispersing agent: Polycaprolactone (molecular weight 2000) 10 parts
100 parts of ethyl acetate
[0052]
(B) Adjustment of micronized wax
The following materials were put into a disperser equipped with a stirring blade and having a function of circulating a heat medium around the container. The temperature was gradually raised while stirring at 83 rpm, the temperature was raised to 100 ° C., and the mixture was stirred for 3 hours while maintaining the temperature at 100 ° C. Next, while continuing stirring, the mixture was cooled to room temperature at a rate of about 2 ° C. per minute to precipitate finely divided wax. When the average particle size of the wax was measured using a laser diffraction / scattering particle size distribution analyzer “LA-700” (manufactured by Horiba, Ltd.), it was about 1.02 μm. Using this high-pressure emulsifier “APV GAULIN HOMOGENIZER 15MR type” (manufactured by APPVGAULIN), this wax dispersion is subjected to a pressure of 5.10 × 10.^FiveDispersion was performed again at Pa (500 KG / CM2). Similarly, the wax particle size was measured and found to be 0.81 μm. The prepared micronized wax dispersion was diluted with ethyl acetate so that the weight concentration of the wax was 15% by weight.
Paraffin wax: (melting point: 85 ° C, latent heat of fusion: 193 mJ / mg) 15 parts
Toluene 85 parts
[0053]
(C) Preparation of oil phase solution
The following materials were mixed after confirming that the binder resin was sufficiently dissolved in the solvent, and the mixture was put into a homomixer “ACE Homogenizer” (manufactured by Nippon Seiki Co., Ltd.) and stirred for 2 minutes at 15000 rpm, A uniform oil phase solution was prepared.
Binder resin A: 70 parts
Binder resin B: 30 parts
Colorant dispersion: (pigment concentration 10% by weight) 50 parts
Fine particle wax dispersion: (wax concentration 15% by weight) 33 parts
32 parts of ethyl acetate
[0054]
(D) Preparation of aqueous phase solution
“Calcium carbonate aqueous solution” and “carboxyl methylcellulose aqueous solution” used as the aqueous phase solution were prepared.
(D-1) Preparation of aqueous calcium carbonate solution
The following materials were stirred with a ball mill for 4 days to obtain an aqueous calcium carbonate solution. When the average particle size of calcium carbonate was measured using the above-described laser diffraction / scattering particle size distribution analyzer “LA-700” (manufactured by Horiba, Ltd.), it was about 0.08 μm.
Calcium carbonate: (average particle size 0.03 μm) 60 parts
40 parts of pure water
(D-2) Preparation of aqueous carboxymethyl cellulose solution
2 parts of carboxymethylcellulose “Serogen BSH” (Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved in 98 parts of pure water to obtain a carboxymethylcellulose aqueous solution.
[0055]
(E) Toner granulation
60 parts of the oil phase solution, 10 parts of the calcium carbonate aqueous solution, and 30 parts of the carboxymethyl cellulose aqueous solution were put into a colloid mill (manufactured by Nippon Seiki Co., Ltd.) and emulsified for 20 minutes at a gap interval of 1.5 mm and 8000 rpm. Next, the emulsion was put into a rotary evaporator, and desolvation was performed at room temperature under reduced pressure of 3990 Pa (30 mmHg) for 3 hours. Thereafter, 12N hydrochloric acid was added until the pH reached 2, and calcium carbonate was removed from the toner surface. Thereafter, 10N sodium hydroxide was added until the pH reached 10, and stirring was continued for 1 hour while stirring with an agitator in an ultrasonic cleaning tank. Further, centrifugal sedimentation was performed, and the supernatant was changed and washed three times, followed by drying to obtain a magenta toner.
The volume average particle size of the toner measured using a Coulter counter “TA-II type” (manufactured by Coulter Co.) is 6.5 μm, and GSD (volume average particle size, d84 / d16 route) is obtained as an index of particle size distribution. ) Was 1.22 and the shape factor MLS2 was 107.
[0056]
(F) Adjustment of developer
To the toner prepared in (E), 0.5 part by weight of silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) was added using a Henschel mixer. A carrier coated with 0.5 parts by weight of polymethyl methacrylate and kneader on “F300” (manufactured by Powdertech) as a carrier core was prepared for this toner, and the toner was adjusted so that the toner weight concentration was 8%. A developer was used.
[0057]
(Example 2)
A cyan toner was produced in the same manner as in Example 1 except that the color material and the synergist were changed as follows when adjusting the color material dispersion. Further, using this toner, a cyan color developer was obtained in the same manner as in Example 1.
Cyan pigment: (C.I.Pigment Bull-15: 3,
Cyan Inmble-4933M; manufactured by Dainichi Seika Co., Ltd.) 88 parts
Synergist: 1-aminoanthraquinone-2-carboxylic acid 2 parts
[0058]
(Example 3)
A yellow toner was prepared in the same manner as in Example 1 except that the color material and the synergist were changed as follows when adjusting the color material dispersion. Further, using this toner, a yellow color developer was obtained in the same manner as in Example 1.
Yellow pigment: (C.I.Pigment Yellow-180, manufactured by Hoechst) 88 parts
Synergist: 2 parts of the following compound (P is C.I.PIGMENT YELLOW180)
[0059]
[Chemical 1]

[0060]
Example 4
A black toner was prepared in the same manner as in Example 1 except that the colorant and the synergist were changed as follows when adjusting the colorant dispersion. Further, using this toner, a black color developer was obtained in the same manner as in Example 1.
Carbon black (# 25, manufactured by Mitsubishi Chemical Corporation) 88 parts
Synergist: 2 parts dimethylaminoethylquinacridone
[0061]
(Example 5)
A magenta toner was produced in the same manner as in Example 1 except that the polymer dispersant was changed to a polymer of 12-hydroxystearic acid (acid value 20 mgKOH / g) when adjusting the colorant dispersion. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1.
[0062]
(Example 6)
The binder resin was changed from binder resin A and binder resin B to binder resin C and binder resin D, except that the synergist was changed to dihydroxyquinacridone and the polymer dispersant was changed to polycaprolactone (molecular weight 5000). A magenta toner was produced in the same manner as in Example 1. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1.
[0063]
(Example 7)
A magenta toner was produced in the same manner as in Example 6 except that the synergist was replaced with dimethylaminoethylquinacridone. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1.
[0064]
(Example 8)
A magenta toner was produced in the same manner as in Example 5 except that the binder resin was only the binder resin E, which was linear polyester. The average particle size of the pigment was measured to be 0.3 μm. The average particle size of the toner was 7.8 μm, and the GSD was 1.35. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1. Example 1 In the same manner, a developer was prepared and evaluated with an actual machine. The OHP image was clear and good. The hot offset temperature of the image occurred at 155 ° C. and the oilless fixer was insufficient. When continuously evaluated, the image quality was good up to 8000 sheets with little image deterioration. Also, no dirt in the machine occurred. The image at high temperature and high humidity was also good with no image distortion. The toner thermal preservation index was 19%.
[0065]
(Reference Example) Old Example 9
Binder resin A 60 parts
Binder resin 26 parts
Magenta pigment: (CI Pigment Red 122, ECR186Y,
                                          Dainichi Seika Co., Ltd.) 6 parts
Synergist: 2 parts dimethylaminoethylquinacridone
Polymer dispersant: Polycaprolactone (molecular weight 2000) 2 parts
Paraffin wax: (melting point: 85 ° C., latent heat of fusion: 193 mJ / mg) 4 parts
The mixture having the above composition was melt-kneaded using a BR Banbury mixer, then coarsely pulverized using a Fitzmill, and further finely pulverized using a jet mill. The pulverized toner was classified using a wind classifier to produce an irregular toner.
  The average toner diameter was 7.2 μm, MLS2 was 154, and the pigment dispersion diameter was 0.3 μm. A magenta color developer was obtained in the same manner as in Example 1. In addition, the developer was prepared in the same manner as in Example 1 and evaluated with an actual machine. The OHP image was clear and good. No hot offset of the image occurred at 200 ° C. Even when the continuous evaluation was performed, the image was not deteriorated up to 8000 sheets, and a good image with little contamination in the machine was obtained.
[0066]
(Example 10)
FIG. 4 is a schematic view showing the structure of a non-magnetic one-component developing unit that can be used in the image forming method of the present invention. The nonmagnetic one-component developing unit shown in FIG. 4 includes a toner reservoir 11, a supply roll 12, a seal material 13, a developing roll 14, and a regulating blade 15.
Image quality was evaluated using a modified “Laser Press 4161” (manufactured by Fuji Xerox Co., Ltd.) equipped with the toner described in Example 1 and the nonmagnetic one-component developing unit shown in FIG. For a solid roll image with a fixing temperature of 155 ° C., the solid portion image has an incident measurement angle of 60/60, and when the toner adhesion amount is 0.6 to 0.7 mg / cm, the glossiness of any color is 20 It showed the above high gloss. Also, the offset temperature did not occur even at 210 ° C. or higher. The OHP image was also clear and good.
[0067]
(Comparative Example 1)
A cyan toner was prepared in the same manner as in Example 2 except that both the synergist and the polymer dispersant were not used. The average particle size of the pigment was measured to be about 0.8 μm. The average particle size of the toner was 8.3 μm, and the GSD was 1.35. Further, using this toner, a cyan color developer was obtained in the same manner as in Example 2.
[0068]
(Comparative Example 2)
A magenta toner was prepared in the same manner as in Example 1 except that no synergist was used. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1. When this developer was evaluated, the OHP image had a good solid image portion, but a portion having an image area ratio of 20 to 30% was dark and sufficient color development was not obtained.
[0069]
(Comparative Example 3)
  Everything except without synergistsReference exampleA toner was prepared in the same manner as described above. The pigment dispersion diameter was 1.5 μm. Further, using this toner, a magenta color developer was obtained in the same manner as in Example 1. When this developer was evaluated, the OHP image was dark and the image quality was low.
[0070]
[Toner Evaluation Method]
The obtained toner and developer were evaluated by the following methods. The evaluation results are shown in Table 2 together with toner physical properties (volume average particle size of toner, GSD as an index of particle size distribution, shape factor MLS2).
[0071]
[Table 2]

[0072]
(1) OHP permeability and color development
Using the developer obtained for each color and using an image output evaluation device modified from “A Color 635” (manufactured by Fuji Xerox Co., Ltd.) on the OHP sheet and plain paper without supplying oil to the heat fixing roll. Image formation was performed. (The outline of the image output evaluation apparatus is shown in FIG. 1) Conditions for image formation are shown below. The developing roll, the interval between the photosensitive member and the developing roller, the interval between the photosensitive member and the developing roller, and the developing bias are common to the developing devices of the respective colors.
[0073]
Photoconductor OPC (φ84)
ROS optical system LED (400 dpi)
Process speed 160mm / s
Latent image potential Background portion = −550V, Image portion = −150V
Developing roll Magnet fixed, sleeve rotation, magnet magnetic flux density = 500G (on sleeve), sleeve diameter = φ25, sleeve rotation speed = 300 mm / s
Distance between photoconductor and developing roll 0.5mm
Distance between developer layer thickness regulating member and developing roll 0.5 mm
Development bias DC component = -500V, AC component = 1.5kVP-P (8kHz)
Transfer conditions Corotron transfer (wire diameter = 85μm)
Fixing conditions Fluorine roll, no oil supply
Environmental conditions Normal temperature and humidity (23 ℃, 50% RH)
And high temperature and high humidity (28 ℃, 85% RH)
[0074]
Evaluation of OHP permeability is performed by measuring the light transmittance at the following wavelength for each color of an image formed on an OHP sheet using a spectrophotometer “U-3210” (manufactured by Hitachi, Ltd.). went.
Cyan --------- 480nm
Magenta -------- 680nm
Yellow -------- 580nm
[0075]
The evaluation of color development was performed by forming a solid image on plain paper at a fixing temperature of 155 ° C., and irradiating white light on the solid image portion with an incident measurement angle of 60/60 and a toner adhesion amount of 0.6. The glossiness at -0.7 mg / cm was measured with a gloss meter. A glossiness of 20 or higher is defined as high gloss.
[0076]
(2) Charging / developability (charge amount, transfer efficiency, image density and fog)
(Charge amount)
The charge amount of the obtained toner was measured according to Examples 1 to 9 and Comparative Examples 1 to 3. Each color developer using the toner of the present invention had a charge amount of −15 to −20 μC / g, and there was almost no difference depending on the pigment. On the other hand, the toner of Comparative Example 1 was −14 μC / g, the toner of Comparative Example 2 was −15 μC / g, and the toner of Comparative Example 3 was −14 μC / g.
[0077]
(Transfer efficiency)
To measure the transfer efficiency 1 from the photoreceptor to the intermediate transfer body, the toner image on the photoreceptor is collected with a transparent adhesive tape, and the image is measured with a color reflection densitometer. Next, a toner image was prepared again, and the toner image was transferred to an intermediate transfer member and similarly collected with an adhesive tape, and the image density was measured. The transfer efficiency is calculated according to the following formula.
[0078]
Transfer efficiency 1 = (toner image density collected from intermediate transfer member) / (toner image density collected from photoconductor)
[0079]
Similarly, the transfer efficiency from the intermediate transfer member to the transfer material is calculated according to the following equation.
[0080]
Transfer efficiency 2 = (toner image density collected from the transfer material) / (toner image density collected from the intermediate transfer member)
[0081]
The final transfer efficiency is calculated according to the following formula.
[0082]
Final transfer efficiency = Transfer efficiency 1 x Transfer efficiency 2
[0083]
(Image density and fog)
An image is formed on plain paper under the same conditions as in the OHP transmission and color development evaluation, and the image density is measured with a color reflection densitometer “X-rite 404A” (manufactured by X-rite). It was measured. The presence or absence of fog in the non-image area was confirmed by visual observation.
[0084]
(3) Fixability
(Offset resistance)
The offset temperature was measured by a modified machine of “A-Color” manufactured by Fuji Xerox Co., Ltd., and the offset resistance was judged according to the following criteria.
Offset temperature less than 150 ° C .................. ×
Offset temperature 150 ° C or higher and lower than 180 ° C ...
Offset temperature 180 ° C or higher ...
[0085]
(Fixed image strength)
An image was formed on plain paper under the same conditions as in the evaluation of OHP permeability and color developability, and the fixed image strength was judged according to the following criteria.
Good ---- There is no peeling of toner by squeezing the image fixed at a roll temperature of 180 ° C
Inferior
[0086]
(4) Other
Also, 5 g of toner was left in a chamber at 45 ° C. and 50% RH for 17 hours, and then returned to room temperature. When the thermal blocking property of the toner was evaluated by a method of measuring the weight of the remaining toner and calculating the weight ratio (thermal blocking index), the toner of the present invention had a thermal blocking index of less than 6% and little aggregation. Excellent stability during storage. Furthermore, the image obtained using the toner of the present invention had good high resolution and no offset to the transfer material. Further, 30,000 sheets were copied continuously, but the image after 30,000 sheets was a good one that did not change from the initial one. Furthermore, image evaluation was performed at high temperature and high humidity, but there was no image distortion.
On the other hand, the toner of Comparative Example 1 has a high thermal blocking index of 8.4% and inferior storage stability, and the resulting image has good high resolution, but 30,000 sheets were copied continuously. In this case, the image quality after 30,000 images was slightly deteriorated compared to the initial image. Further, with the toner of Comparative Example 2, image fogging under high temperature and high humidity was observed.
[0087]
From the above examples, the toner of the present invention can be used as a one-component developer or a two-component developer, and was prepared by a dissolution suspension method or a kneading pulverization method? Regardless of this, it can be seen that the light transmittance after toner fixing is 85% or more, which is excellent in OHP transparency, and also has high glossiness and excellent color developability. Further, the charge amount of the developer is sufficient from −15 to −20 μC / g, the transfer efficiency of each color from the photoreceptor 1 to the intermediate transfer member 4 is 98 to 99%, and the transfer from the intermediate transfer member 4 to the transfer material 10 is achieved. It can be seen that the transfer efficiency is 98 to 99%, and the overall transfer efficiency is 96 to 98%. Further, it has a high development density, little fogging, and excellent charging and development characteristics.
In addition, when a binder resin containing a non-linear resin is used, the OHP permeability and color developability are also excellent, and at the same time, the performance of the binder resin is fully demonstrated, and a high temperature of 180 ° C. It can be seen that no offset occurs, the fixing property is excellent, and the image fixing strength is also excellent.
Furthermore, it can be seen that the toner of the present invention does not impair various properties such as storage stability and environmental dependency.
[0088]
On the other hand, when neither a synergist nor a polymer dispersant is used, it can be seen that the OHP image has a dark halftone and is inferior in transparency. In addition, it can be seen that the hot offset of the image occurs at 145 ° C., and the fixing property without oil is insufficient (Comparative Example 1). When a polymer dispersant is used but no synergist is used, solid OHP color development is sufficient, but color development at a low image density portion is insufficient (Comparative Examples 2 and 3). .
[0089]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a toner for developing an electrostatic latent image that has good dispersibility of a coloring material, excellent transparency and color developability, and has stable chargeability and developability. Can do.
In particular, even when a non-linear resin having a cross-linked structure is used as a binder resin, the dispersibility of the coloring material can be stabilized, and the fixing property is excellent, and at the same time, the transparency, coloring property, charging It is possible to provide a toner for developing an electrostatic latent image that is excellent in properties and developability and is particularly suitable for forming a color image. That is, even if toners of cyan, magenta, yellow, and black are overlaid, it is possible to reproduce a good color tone, and it is possible to realize any color tone by an ideal subtractive color mixing method.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a DSC endothermic curve of wax.
FIG. 2 is a schematic view showing a cross section of toner particles.
FIG. 3 is a schematic diagram showing an example of a color image forming apparatus that can be used in the image forming method of the present invention.
FIG. 4 is a schematic view showing the structure of a non-magnetic one-component developing unit that can be used in the image forming method of the present invention.
[Explanation of symbols]
1 photoconductor (electrostatic latent image carrier),
2 Corona charger,
3 Exposure equipment
4 Intermediate transfer member,
5 Four-color developer (5a, 5b, 5c, 5d)
6 Transfer charger,
7 Cleaner
8 Heating roller
9 Pressure roller
10 Transfer material
11 Toner reservoir,
12 supply rolls,
13 Sealing material
14 Developing roll,
15 Regulatory blade

Claims (13)

An electrostatic latent image obtained by suspending and granulating an oil phase containing at least a binder resin and a color material, and at least a binder component and a toner component containing the color material dissolved or dispersed in an organic solvent in an aqueous phase. In developing toner,
The colorant is dispersed by a polymer dispersant and a synergist having a common skeleton with the colorant and having a polar functional group that interacts with the polymer dispersant,
A toner for developing an electrostatic latent image, wherein the shape factor MLS2 defined by the following formula is in a range of 100 to 140.
MLS2 = ( absolute maximum length of toner particles ) ² / ( projection area of toner particles ) × π × 1/4 × 100   The electrostatic latent image developing toner according to claim 1, wherein the color material is dispersed in the toner with a number average diameter of 0.7 μm or less.   The electrostatic latent image developing toner according to claim 1, wherein the synergist is a pigment derivative.   The electrostatic latent image developing toner according to any one of claims 1 to 3, wherein the polymer dispersant is made of the same kind of resin as the binder resin.   5. The electrostatic latent image developing according to claim 1, wherein the synergist is blended at a ratio of 0.1 wt% to 100 wt% with respect to the color material. toner.   6. The electrostatic latent image developing toner according to claim 1, wherein the binder resin contains a non-linear resin.   The non-linear resin is a polyester resin having a cross-linked structure in which a diol component and a dicarboxylic acid component repeatedly introduce a trivalent or higher polyvalent carboxylic acid component as a cross-linkable monomer component into a linear polymer chain. The electrostatic latent image developing toner according to claim 6.   The toner for developing an electrostatic latent image according to any one of claims 1 to 7, further comprising a release agent. An oil phase adjustment step for adjusting an oil phase by dissolving or dispersing a toner component containing at least a binder resin and a colorant in an organic solvent, and a granulation step for suspending and granulating the oil phase component in an aqueous phase; In the method for producing a toner for developing an electrostatic latent image having a solvent removing step of removing the solvent,
  The color material is dispersed by a polymer dispersant and a synergist having a skeleton common to the color material and having a polar functional group that interacts with the polymer dispersant. A method for producing a toner for developing a latent image. The method for producing a toner for developing an electrostatic latent image according to claim 9, wherein in the oil phase adjustment step, the color material is dispersed again under high-speed shearing. An electrostatic latent image developer using the electrostatic latent image developing toner according to any one of claims 1 to 8. A latent image forming step for forming a latent image on the latent image carrier, a developing step for developing the latent image with a developer, a transfer step for transferring a toner image on the latent image carrier to a transfer member, An image forming method comprising: a fixing step of fixing a toner image on a transfer body, wherein the electrostatic latent image developer according to claim 11 is used as the developer. A latent image forming step of forming a latent image on the latent image carrier, a developing step of developing the latent image with a developer composed of cyan, magenta, yellow, and black color toners; on the latent image carrier; The electrostatic latent image developer according to claim 12 is used as the developer in a full-color image forming method having a transfer step of transferring the toner image to a transfer member and a fixing step of fixing the toner image on the transfer member. A full-color image forming method.

Images