JP2004246081A - Black toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black toner excellent in dispersibility of carbon black and a release agent, and having a wide fixable temperature range. <P>SOLUTION: An ultramarine having a particle diameter of 0.3-3.0 μm is incorporated into a toner to improve the dispersibility of carbon black and a release agent. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

（上記式中、Ｒはエチレンまたはプロピレン基を示し、ｘ、ｙはそれぞれ１以上の整数であり、且つ、ｘ＋ｙの平均値は２〜１０である。）
【００６０】
本発明の結着樹脂として、ビニル系重合体及び／またはハイブリッド樹脂を用いる場合に、これらを構成するビニル系モノマーとしては、次のようなものが挙げられる。スチレン；ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、α−メチルスチレン、ｐ−フェニルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｎ−ブチルスチレン、ｐ−ｔｅｒｔ−ブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレン、ｐ−メトキシスチレン、ｐ−クロルスチレン、３，４−ジクロルスチレン、ｍ−ニトロスチレン、ｏ−ニトロスチレン、ｐ−ニトロスチレンの如きスチレン及びその誘導体；エチレン、プロピレン、ブチレン、イソブチレンの如きスチレン不飽和モノオレフィン類；ブタジエン、イソプレンの如き不飽和ポリエン類；塩化ビニル、塩化ビニリデン、臭化ビニル、フッ化ビニルの如きハロゲン化ビニル類；酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニルの如きビニルエステル類；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、メタクリル酸２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸フェニル、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如きα−メチレン脂肪族モノカルボン酸エステル類；アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ｎ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−オクチル、アクリル酸ドデシル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸２−クロルエチル、アクリル酸フェニルの如きアクリル酸エステル類；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルの如きビニルエーテル類；ビニルメチルケトン、ビニルヘキシルケトン、メチルイソプロペニルケトンの如きビニルケトン類；Ｎ−ビニルピロール、Ｎ−ビニルカルバゾール、Ｎ−ビニルインドール、Ｎ−ビニルピロリドンの如きＮ−ビニル化合物；ビニルナフタリン類；アクリロニトリル、メタクリロニトリル、アクリルアミドの如きアクリル酸もしくはメタクリル酸誘導体等が挙げられる。
【００６１】
さらに、マレイン酸、シトラコン酸、イタコン酸、アルケニルコハク酸、フマル酸、メサコン酸の如き不飽和二塩基酸；マレイン酸無水物、シトラコン酸無水物、イタコン酸無水物、アルケニルコハク酸無水物の如き不飽和二塩基酸無水物；マレイン酸メチルハーフエステル、マレイン酸エチルハーフエステル、マレイン酸ブチルハーフエステル、シトラコン酸メチルハーフエステル、シトラコン酸エチルハーフエステル、シトラコン酸ブチルハーフエステル、イタコン酸メチルハーフエステル、アルケニルコハク酸メチルハーフエステル、フマル酸メチルハーフエステル、メサコン酸メチルハーフエステルの如き不飽和二塩基酸のハーフエステル；ジメチルマレイン酸、ジメチルフマル酸の如き不飽和二塩基酸エステル；アクリル酸、メタクリル酸、クロトン酸、ケイヒ酸の如きα，β−不飽和酸；クロトン酸無水物、ケイヒ酸無水物の如きα，β−不飽和酸無水物、該α，β−不飽和酸と低級脂肪酸との無水物；アルケニルマロン酸、アルケニルグルタル酸、アルケニルアジピン酸、これらの酸無水物及びこれらのモノエステルの如きカルボキシル基を有するモノマーが挙げられる。
【００６２】
さらに、２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート、２−ヒドロキシプロピルメタクリレートなどのアクリル酸またはメタクリル酸エステル類；４−（１−ヒドロキシ−１−メチルブチル）スチレン、４−（１−ヒドロキシ−１−メチルヘキシル）スチレンの如きヒドロキシ基を有するモノマーが挙げられる。
【００６３】
本発明のトナーにおいて、結着樹脂として用いられるビニル系重合体及び／またはハイブリッド樹脂のビニル系重合体ユニットは、ビニル基を２個以上有する架橋剤で架橋された架橋構造を有していてもよい。この場合に用いられる架橋剤は、芳香族ジビニル化合物として例えば、ジビニルベンゼン、ジビニルナフタレンが挙げられ；アルキル鎖で結ばれたジアクリレート化合物類として例えば、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールジアクリレート、１，６ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート及び以上の化合物のアクリレートをメタクリレートに代えたものが挙げられ；エーテル結合を含むアルキル鎖で結ばれたジアクリレート化合物類としては、例えば、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコール＃４００ジアクリレート、ポリエチレングリコール＃６００ジアクリレート、ジプロピレングリコールジアクリレート及び以上の化合物のアクリレートをメタアクリレートに代えたものが挙げられ；芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類として例えば、ポリオキシエチレン（２）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート、ポリオキシエチレン（４）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート及び以上の化合物のアクリレートをメタクリレートに代えたものが挙げられる。
【００６４】
多官能の架橋剤としては、ペンタエリスリトールトリアクリレート、トリメチロールエタントリアクリレート、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート及び以上の化合物のアクリレートをメタクリレートに代えたもの；トリアリルシアヌレート、トリアリルトリメリテートが挙げられる。
【００６５】
本発明ではビニル系重合体成分及び／またはポリエステル樹脂成分中に、両樹脂成分と反応し得るモノマー成分を含むことが好ましい。ポリエステル樹脂成分を構成するモノマーのうちビニル系重合体と反応し得るものとしては、例えば、フタル酸、マレイン酸、シトラコン酸、イタコン酸の如き不飽和ジカルボン酸またはその無水物などが挙げられる。ビニル系重合体成分を構成するモノマーのうちポリエステル樹脂成分と反応し得るものとしては、カルボキシル基またはヒドロキシ基を有するものや、アクリル酸もしくはメタクリル酸エステル類が挙げられる。
【００６６】
ビニル系重合体とポリエステル樹脂の反応生成物を得る方法としては、先に挙げたビニル系重合体及びポリエステル樹脂のそれぞれと反応しうるモノマー成分を含むポリマーが存在しているところで、どちらか一方もしくは両方の樹脂の重合反応をさせることにより得る方法が好ましい。
【００６７】
本発明にかかるビニル系重合体及びビニル系重合体ユニットを製造する場合に用いられる重合開始剤としては、例えば、２，２’−アゾビスイソブチロニトリル、２，２’−アゾビス（４−メトキシ−２，４−ジメチルバレロニトリル）、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（２−メチルブチロニトリル）、ジメチル−２，２’−アゾビスイソブチレート、１，１’−アゾビス（１−シクロヘキサンカルボニトリル）、２−（カーバモイルアゾ）−イソブチロニトリル、２，２’−アゾビス（２，４，４−トリメチルペンタン）、２−フェニルアゾ−２，４−ジメチル−４−メトキシバレロニトリル、２，２’−アゾビス（２−メチル−プロパン）、メチルエチルケトンパーオキサイド、アセチルアセトンパーオキサイド、シクロヘキサノンパーオキサイドの如きケトンパーオキサイド類、２，２−ビス（ｔｅｒｔ−ブチルパーオキシ）ブタン、ｔｅｒｔ−ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド、１，１，３，３−テトラメチルブチルハイドロパーオキサイド、ジ−ｔｅｒｔ−ブチルパーオキサイド、ｔｅｒｔ−ブチルクミルパーオキサイド、ジ−クミルパーオキサイド、α，α’−ビス（ｔｅｒｔ−ブチルパーオキシイソプロピル）ベンゼン、イソブチルパーオキサイド、オクタノイルパーオキサイド、デカノイルパーオキサイド、ラウロイルパーオキサイド、３，５，５−トリメチルヘキサノイルパーオキサイド、ベンゾイルパーオキサイド、ｍ−トリオイルパーオキサイド、ジ−イソプロピルパーオキシジカーボネート、ジ−２−エチルヘキシルパーオキシジカーボネート、ジ−ｎ−プロピルパーオキシジカーボネート、ジ−２−エトキシエチルパーオキシカーボネート、ジ−メトキシイソプロピルパーオキシジカーボネート、ジ（３−メチル−３−メトキシブチル）パーオキシカーボネート、アセチルシクロヘキシルスルホニルパーオキサイド、ｔｅｒｔ−ブチルパーオキシアセテート、ｔｅｒｔ−ブチルパーオキシイソブチレート、ｔｅｒｔ−ブチルパーオキシネオデカノエイト、ｔｅｒｔ−ブチルパーオキシ２−エチルヘキサノエイト、ｔｅｒｔ−ブチルパーオキシラウレート、ｔｅｒｔ−ブチルパーオキシベンゾエイト、ｔｅｒｔ−ブチルパーオキシイソプロピルカーボネート、ジ−ｔｅｒｔ−ブチルパーオキシイソフタレート、ｔｅｒｔ−ブチルパーオキシアリルカーボネート、ｔｅｒｔ−アミルパーオキシ２−エチルヘキサノエート、ジ−ｔｅｒｔ−ブチルパーオキシヘキサハイドロテレフタレート、ジ−ｔｅｒｔ−ブチルパーオキシアゼレートが挙げられる。
【００６８】
本発明に用いられるハイブリッド樹脂の製造方法としては、例えば、以下の（１）〜（６）に示す製造方法を挙げることができる。
【００６９】
（１）ビニル系重合体、ポリエステル樹脂及びハイブリッド樹脂成分をそれぞれ製造後にブレンドする方法であり、ブレンドは有機溶剤（例えば、キシレン）に溶解・膨潤した後に有機溶剤を留去して製造される。尚、ハイブリッド樹脂成分は、ビニル系重合体とポリエステル樹脂を別々に製造後、少量の有機溶剤に溶解・膨潤させ、エステル化触媒及びアルコールを添加し、加熱することによりエステル交換反応を行なって合成されるエステル化合物を用いることができる。
【００７０】
（２）ビニル系重合体ユニット製造後に、これの存在下にポリエステルユニット及びハイブリッド樹脂成分を製造する方法である。ハイブリッド樹脂成分はビニル系重合体ユニット（必要に応じてビニル系モノマーも添加できる）とポリエステルモノマー（アルコール、カルボン酸）及び／またはポリエステルとの反応により製造される。この場合も適宜、有機溶剤を使用することができる。
【００７１】
（３）ポリエステルユニット製造後に、これの存在下にビニル系重合体ユニット及びハイブリッド樹脂成分を製造する方法である。ハイブリッド樹脂成分はポリエステルユニット（必要に応じてポリエステルモノマーも添加できる）とビニル系モノマー及び／またはビニル系重合体ユニットとの反応により製造される。
【００７２】
（４）ビニル系重合体ユニット及びポリエステルユニット製造後に、これらの重合体ユニット存在下にビニル系モノマー及び／またはポリエステルモノマー（アルコール、カルボン酸）を添加することによりハイブリッド樹脂成分が製造される。この場合も適宜、有機溶剤を使用することができる。
【００７３】
（５）ハイブリッド樹脂成分を製造後、ビニル系モノマー及び／またはポリエステルモノマー（アルコール、カルボン酸）を添加して付加重合及び／または縮重合反応を行うことによりビニル系重合体ユニット及びポリエステルユニットが製造される。この場合、ハイブリッド樹脂成分は上記（２）〜（４）の製造方法により製造されるものを使用することもでき、必要に応じて公知の製造方法により製造されたものを使用することもできる。さらに、適宜、有機溶剤を使用することができる。
【００７４】
（６）ビニル系モノマー及びポリエステルモノマー（アルコール、カルボン酸等）を混合して付加重合及び縮重合反応を連続して行うことによりビニル系重合体ユニット、ポリエステルユニット及びハイブリッド樹脂成分が製造される。さらに、適宜、有機溶剤を使用することができる。
【００７５】
上記（１）〜（５）の製造方法において、ビニル系重合体ユニット及び／またはポリエステルユニットは複数の異なる分子量、架橋度を有する重合体ユニットを使用することができる。
【００７６】
本発明のトナーに用いられる結着樹脂のガラス転移温度は４０〜９０℃が好ましく、より好ましくは４５〜８５℃である。また、結着樹脂の酸価は１〜４０ｍｇＫＯＨ／ｇであることが好ましい。
【００７７】
次に本発明に用いられる離型剤について説明する。
【００７８】
本発明に用いられる離型剤としては、一種または二種以上のワックスが望ましい。
【００７９】
該ワックスを含有した本発明のトナーは、低温定着性と耐ブロッキング性を両立するという観点から、示差熱分析（ＤＳＣ）測定における吸熱曲線において、温度３０〜２００℃の範囲に１個または複数の吸熱ピークを有し、該吸熱ピーク中の最大吸熱ピークのピーク温度が６０〜１１０℃の範囲にあることが望ましい。より好ましくは６５〜１００℃の範囲に吸熱曲線の最大ピークがあることが望ましい。最大吸熱ピークのピーク温度が６０℃未満である場合はトナーの耐ブロッキング性が悪くなり、逆に最大吸熱ピークのピーク温度が１１０℃超の場合は定着性が低下してしまう。
【００８０】
本発明に用いられるワックスとしては、例えば低分子量ポリエチレン、低分子量ポリプロピレン、マイクロクリスタリンワックス、パラフィンワックスなどの脂肪族炭化水素系ワックス、また酸化ポリエチレンワックスなどの脂肪族炭化水素系ワックスの酸化物、またはそれらのブロック共重合物；カルナバワックス、サゾールワックス、モンタン酸エステルワックスなどの脂肪酸エステルを主成分とするワックス類、及び脱酸カルナバワックスなどの脂肪酸エステル類を一部または全部を脱酸化したものなどが挙げられる。さらに、パルミチン酸、ステアリン酸、モンタン酸などの飽和直鎖脂肪酸類；ブランジン酸、エレオステアリン酸、バリナリン酸などの不飽和脂肪酸類；ステアリルアルコール、アラルキルアルコール、ベヘニルアルコール、カルナウビルアルコール、セリルアルコール、メリシルアルコールなどの飽和アルコール類；ソルビトールなどの多価アルコール類；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドなどの脂肪酸アミド類；メチレンビスステアリン酸アミド、エチレンビスカプリン酸アミド、エチレンビスラウリン酸アミド、ヘキサメチレンビスステアリン酸アミドなどの飽和脂肪酸ビスアミド類；エチレンビスオレイン酸アミド、ヘキサメチレンビスオレイン酸アミド、Ｎ，Ｎ’−ジオレイルアジピン酸アミド、Ｎ，Ｎ’−ジオレイルセバシン酸アミドなどの不飽和脂肪酸アミド類；ｍ−キシレンビスステアリン酸アミド、Ｎ，Ｎ’−ジステアリルイソフタル酸アミドなどの芳香族系ビスアミド類；ステアリン酸カルシウム、ラウリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムなどの脂肪族金属塩（一般に金属石けんといわれているもの）；脂肪族炭化水素系ワックスにスチレンやアクリル酸などのビニル系モノマーを用いてグラフト化させたワックス類；ベヘニン酸モノグリセリドなどの脂肪酸と多価アルコールの部分エステル化物；植物性油脂の水素添加などによって得られるヒドロキシル基を有するメチルエステル化合物などが挙げられる。
【００８１】
また、この他に、本発明において好ましく用いられるワックスとしては、脂肪族炭化水素系ワックスが挙げられる。例えば、アルキレンを高圧下でラジカル重合或いは低圧下でチーグラー触媒で重合した低分子量のアルキレンポリマー；高分子量のアルキレンポリマーを熱分解して得られるアルキレンポリマー；一酸化炭素及び水素を含む合成ガスからアーゲ法により得られる炭化水素の蒸留残分から、或いはこれらを水素添加して得られる合成炭化水素ワックスがよい。さらにプレス発汗法、溶剤法、真空蒸留の利用や分別結晶方式により炭化水素ワックスの分別を行ったものが、より好ましく用いられる。母体としての炭化水素は、金属酸化物系触媒（多くは２種以上の多元系）を使用した一酸化炭素と水素の合成によって合成されるもの〔例えばジントール法、ヒドロコール法（流動触媒床を使用）によって合成された炭化水素化合物〕；ワックス状炭化水素が多く得られるアーゲ法（同定触媒床を使用）により得られる炭素数が数百ぐらいまでの炭化水素；エチレンなどのアルキレンをチーグラー触媒により重合した炭化水素が、分岐が少なくて小さく、飽和の長い直鎖状炭化水素であるので好ましい。特にアルキレンの重合によらない方法により合成されたワックスがその分子量分布からも好ましいものである。
【００８２】
ワックスの分子量分布では、メインピークが分子量４００〜２４００の領域にあることが好ましく、４３０〜２０００の領域にあることがより好ましい。この様な分子量分布を持たせることによりトナーに好ましい熱特性を付与することができる。
【００８３】
本発明において、離型剤として用いられるワックスは、結着樹脂１００質量部当たり１〜２０質量部用いることが好ましく、さらに好ましくは２〜１０質量部である。
【００８４】
ワックスは通常、樹脂を溶剤に溶解し樹脂溶液温度を上げ、撹拌しながら添加混合する方法や、混練時に混合する方法で結着樹脂に含有される。
【００８５】
本発明のトナーにおいては、帯電安定化のために芳香族カルボン酸誘導体の金属化合物を含有していても良い。これは、荷電制御剤として機能するばかりでなく、カーボンブラックの分散性向上にも寄与する。
【００８６】
芳香族カルボン酸誘導体の金属化合物がカーボンブラックの分散性を向上させる理由は定かではないが、結着樹脂と芳香族カルボン酸誘導体の金属化合物との相互作用によって、一部架橋反応が進み、混練時のカーボンブラックにシェアーを増大させることによって、難分散性のカーボンブラックの分散性が上がったものと考えられる。さらに芳香族カルボン酸誘導体の金属化合物がカーボンブラックの周りを取り囲み、カーボンブラックの分散安定化剤のごとく機能するため、混練時に微分散したカーボンブラックの安定化に効果を発揮し、再凝集抑制剤としても機能していると考えられる。
【００８７】
上記芳香族カルボン酸としては、下記式（２）〜（４）で示される３種の化合物が挙げられる。
【００８８】
【化２】

〔上記式中、Ｒ_１〜Ｒ_７はそれぞれ、水素、炭素数１〜１２のアルキル基、炭素数２〜１２のアルケニル基、−ＯＨ、−ＮＨ_２、−ＮＨ（ＣＨ_３）、−Ｎ（ＣＨ_３）_２、−ＯＣＨ_３、−Ｏ（Ｃ_２Ｈ_５）、−ＣＯＯＨ、−ＣＯＮＨ_２を示す。〕
【００８９】
上記化合物において、好ましいＲ_１としては、ヒドロキシル基、アミノ基及びメトキシ基が挙げられるが、中でもヒドロキシル基が好ましい。芳香族カルボン酸としては、特に、ジ−ｔｅｒｔ−ブチルサリチル酸のアルミニウム化合物が好ましい。
【００９０】
芳香族カルボン酸の金属化合物は、例えば、芳香族カルボン酸を水酸化ナトリウム水溶液に溶解させ、２価以上の金属原子を溶融している水溶液を水酸化ナトリウム水溶液に滴下し、加熱攪拌し、次に水溶液のｐＨを調整し、室温まで冷却した後、ろ過水洗することにより芳香族カルボン酸の金属化合物を合成しうる。但し、上記の合成方法だけに限定されるものではない。
【００９１】
上記芳香族カルボン酸の金属化合物の使用量は、トナーの粘弾性特性及び摩擦帯電特性を調整する上で、結着樹脂１００質量部当たり０．５〜１０質量部が好ましく、より好ましくは１．５〜８質量部である。該金属化合物の使用量が０．５質量部より少ない場合には、荷電制御剤としてあまり機能しないばかりでなく、良好なカーボンブラック分散性が達成できない。一方、１０質量部よりも多いときは、架橋が進みすぎてしまい、トナーとしての定着性が損なわれてしまう。
【００９２】
本発明においては、上記芳香族カルボン酸の金属化合物以外の化合物を荷電制御剤として用いても良い。
【００９３】
本発明のブラックトナーの製造方法としては、例えば、結着樹脂、カーボンブラック、ウルトラマリン、離型剤、さらに必要に応じて荷電制御剤やそのほかの添加剤等をヘンシェルミキサーの如き混合機において十分混合してから、加熱ロール、ニーダー、エクストルーダーの如き熱混練機を用いて溶融、捏和及び練肉して樹脂類を互いに相溶せしめた中にカーボンブラックを分散せしめ、冷却固化後、粉砕及び厳密な分級を行ってブラックトナー粒子を得ることができる。
【００９４】
本発明においては、トナー粒子中のカーボンブラックの分散状態を向上させるために、第１の結着樹脂、ウルトラマリン、カーボンブラックを混練機または混合機に仕込み、非加圧もしくは加圧下で混合しながら加熱して第１の結着樹脂を溶融させ、その後、３本ロールの如き混練機で十分に混練せしめた第１の混練物を得、次いで第１の混練物に第２の結着樹脂、さらに必要に応じて荷電制御剤の如き添加剤や離型剤等を加えた混合物を、加熱溶融混練して第２の混練物を得、得られた第２の混練物を冷却後粉砕及び分級してトナー化することが好ましい。ここで、第１の結着樹脂と第２の結着樹脂は、同じであっても異なる樹脂であっても良い。
【００９５】
また、混練装置としては、加熱ニーダー、一軸押し出し機、二軸押し出し機などが挙げられ、特に好ましくは加熱ニーダーが挙げられる。
【００９６】
本発明のブラックトナーは重量平均粒径が好ましくは４〜１０μｍであり、個数平均粒径が好ましくは３．５〜９．５μｍである。さらに、当該トナーの個数分布における粒径４μｍ以下の粒子が５〜５０個数％であり、体積分布における粒径１２．７０μｍ以上の粒子が５体積％以下であることが好ましい。
【００９７】
トナーの重量平均粒径が１０μｍより大きい場合、高画質化に寄与しうる微粒子が少ないことを意味し、高い画像濃度が得られ易く、トナーの流動性に優れるというメリットがあるものの、感光体ドラム上の微細な静電荷像上には忠実に付着しづらく、ハイライト部の再現性が低下し、さらに解像性も低下する。また、必要以上にトナーが静電荷像に乗りすぎ、トナー消費量の増大を招きやすい傾向もある。
【００９８】
また、トナーの重量平均粒径が４μｍより小さいときには、トナーの単位重量当たりの帯電量が高くなり、画像濃度の低下、特に低温低湿下での画像濃度の低下が顕著となる。そのため、特にグラフィック画像の如き画像面積比率の高い用途には不向きである。
【００９９】
さらに、トナーの重量平均粒径が４μｍより小さいときには、キャリアなどの帯電付与部材との接触帯電がスムーズに行われにくく、十分に帯電し得ないトナーが増大し、非画像部への飛び散りによるカブリが目立つようになる。これに対処すべくキャリアの比表面積を稼ぐためにキャリアの小径化が考えられるが、重量平均粒径が４μｍ未満のトナーでは、トナー自己凝集も起こりやすく、キャリアとの均一混合が短時間では達成されにくく、トナーの連続補給耐久においては、カブリが生じてしまう傾向にある。
【０１００】
また、本発明のトナーは、４μｍ以下の粒径のトナー粒子が全粒子数の５〜５０個数％であることが好ましく、より好ましくは５〜２５個数％である。４μｍ以下の粒径のトナー粒子が５個数％未満であると、高画質のために必須な成分である微小なトナー粒子が少ないことを意味し、特に、コピーまたはプリントアウトを続けることによってトナーが連続的に使われるに従い、有効なトナー粒子成分が減少して、本発明で示すトナーの粒度分布のバランスが悪化し、画質が次第に低下する傾向を示す。
【０１０１】
また、４μｍ以下の粒径のトナー粒子が５０個数％を超えると、トナー粒子相互の凝集状体が生じやすく、本来の粒径のトナー塊として、挙動することも多くなり、その結果、荒れた画像が形成されやすく、解像性を低下させたり、または静電荷像のエッジ部と内部との濃度差が大きくなり、中抜け気味の画像となり易い。さらに、粒径が１２．７０μｍ以上の粒子が５体積％以下であることが画質向上の上で好ましい。
【０１０２】
さらに、本発明のトナーには、流動性向上剤が外添されていることが画質向上、高温環境下でも保存性の点で好ましい。流動性向上剤としては、シリカ、酸化チタン、酸化アルミニウム等の無機微粉体が好ましい。該無機微粉体は、シランカップリング剤、シリコーンオイルまたはそれらの混合物の如き疎水化剤で疎水化されていることが好ましい。
【０１０３】
疎水化剤としては、シランカップリング剤、チタネートカップリング剤、アルミニウムカップリング剤、ジルコアルミネートカップリング剤の如きカップリング剤が挙げられる。
【０１０４】
具体的に、例えばシランカップリング剤としては、一般式
Ｒ_ｍ−Ｓｉ−Ｙ_ｎ
〔上記式中、Ｒはアルコキシ基を示し、ｍは１〜３の整数を示し、Ｙはアルキル基、ビニル基、フェニル基、メタクリル基、アミノ基、エポキシ基、メルカプト基またはこれらの誘導体を示し、ｎは１〜３の整数を示す。〕
で表されるものが好ましい。例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン、γ−メタクリルオキシプロピルトリメトキシシラン、メチルトリメトキシシラン、メチルトリエトキシシラン、イソブチルトリメトキシシラン、ジメチルジメトキシシラン、ジメチルジエトキシシラン、トリメチルメトキシシラン、ヒドロキシプロピルトリメトキシシラン、フェニルトリメトキシシラン、ｎ−ヘキサデシルトリメトキシシラン、ｎ−オクタデシルトリメトキシシラン等を挙げることができる。
【０１０５】
その処理量は、無機微粉体１００質量部に対して、好ましくは１〜６０質量部、より好ましくは３〜５０質量部である。
【０１０６】
本発明において好ましく用いられる疎水化剤は、下記一般式
Ｃ_ｎＨ_２ｎ＋１−Ｓｉ−（ＯＣ_ｍＨ_２ｍ＋１）_３
〔上記式中、ｎは４〜１２の整数を示し、ｍは１〜３の整数を示す。〕
で示されるアルキルアルコキシシランカップリング剤である。該アルキルアルコキシシランカップリング剤において、ｎが４より小さいと、処理は容易になるが疎水化度が低く、好ましくない。ｎが１２より大きいと、疎水性が十分になるが、酸化チタン微粒子同士の合一が多くなり、流動性付与能が低下しやすい。ｍが３より大きいと、該アルキルアルコキシシランカップリング剤の反応性が低下して疎水化を良好に行いにくくなる。より好ましいアルキルアルコキシシランカップリング剤はｎが４〜８であり、ｍが１〜２である。
【０１０７】
アルキルアルコキシシランカップリング剤の処理量は、無機微粉体１００質量部に対して、好ましくは１〜６０質量部、より好ましくは３〜５０質量部である。
【０１０８】
疎水化処理は１種類の疎水化剤単独で行っても良いし、２種類以上の疎水化剤を同時或いは順次併用しても良い。
【０１０９】
上記流動性向上剤は、トナー粒子１００質量部に対して０．０１〜５質量部添加することが好ましく、さらに好ましくは０．０３〜３質量部である。
【０１１０】
本発明のブラックトナーは、一成分系現像剤及び二成分系現像剤のいずれにも適用できるものである。本発明のトナーを二成分系現像剤に用いる場合に併用されるキャリアとしては、例えば表面酸化または未酸化の鉄、ニッケル、銅、亜鉛、コバルト、マンガン、クロム、希土類等の金属及びそれらの合金または酸化物及びフェライトなどが使用できる。
【０１１１】
特に、マンガン、マグネシウム及び鉄を主成分として形成されるＭｎ−Ｍｇ−Ｆｅの３元素の磁性フェライト粒子がキャリア粒子として好ましい。磁性キャリア粒子は、樹脂で被覆されていることが好ましく、該被覆樹脂としては、シリコーン樹脂が好ましい。特に、含窒素シリコーン樹脂、または、含窒素シランカップリング剤とシリコーン樹脂とが反応することにより生成した変性シリコーン樹脂が、本発明のトナーへのマイナスの摩擦電荷の付与性、環境安定性、キャリアの表面の汚染に対する抑制の点で好ましい。
【０１１２】
磁性キャリアは、平均粒径が好ましくは１５〜６０μｍ、より好ましくは２５〜５０μｍであることが、本発明のトナーの重量平均粒径との関係で好ましい。磁性キャリアを当該平均粒径を有するように調整する方法としては、例えば篩を用いることによる分級が挙げられる。特に、精度良く分級を行うために、適当な目開きの篩を用いて複数回繰り返してふるうことが好ましい。また、メッシュの開口の形状をメッキ等によって制御したものを使うことも有効な手段である。
【０１１３】
本発明のトナーを用いて二成分系現像剤を調整する場合、トナーとキャリアとの混合比率は、現像剤中のトナー濃度として２〜１５質量％が好ましく、さらに好ましくは４〜１３質量％にすると、通常良好な結果が得られる。トナー濃度が２質量％未満では画像濃度が低くなりやすく、１５質量％を超える場合ではカブリや機内飛散が増加しやすい。
【０１１４】
本発明のブラックトナーを用いてフルカラー画像を形成する画像形成装置の一例を図１に示し、該装置における画像形成方法について説明する。
【０１１５】
図１に示す画像形成装置は、下部のデジタルカラー画像プリンタ部Ｉと、上部のデジタルカラー画像リーダ部ＩＩとを備えており、例えば、リーダ部ＩＩで読み取った原稿Ｄの画像に基づき、プリンタ部Ｉにおいて記録材Ｐに画像を形成する。
【０１１６】
先ず、プリンタ部Ｉについて説明する。
【０１１７】
プリンタ部Ｉは、矢印Ｒ１方向に回転駆動される静電荷像担持体としての感光体ドラム１を有する。感光体ドラム１の周囲には、その回転方向に沿って順に、一次帯電器（帯電手段）２、露光手段３、現像装置（現像手段）４、転写装置５、クリーニング部６、前露光ランプ７等が配置されている。転写装置５の下方（即ちプリンタ部Ｉの下半部）には、記録材Ｐの給紙搬送部８が配置され、さらに転写装置５の上部には分離手段９が設置され、また分離手段９の下流側（記録材Ｐの搬送方向についての下流側）には加熱加圧定着器１０及び排紙部１１が配置されている。
【０１１８】
感光体ドラム１は、アルミニウム製のドラム上の基体１ａと、その表面を覆うＯＰＣ（有機半導体）の感光体１ｂとを有し、駆動手段（不図示）によって矢印Ｒ１方向に所定のプロセススピード（周速度）で回転駆動されるように構成されている。
【０１１９】
一次帯電器２は、感光体ドラム１に対向する部分が開口したシールド２ａと、シールド２ａの内側に感光体ドラム１の母線と平行に配置された放電ワイヤ２ｂと、シールド２ａの開口部に配置されて帯電電位を規制するグリッド２ｃとを有するコロナ帯電器である。一次帯電器２は、電源（不図示）によって帯電バイアスが印加され、これにより、感光体ドラム１表面を所定の極性、所定の電位に均一に帯電するようになっている。
【０１２０】
露光手段３は、後述のリーダ部ＩＩからの画像信号に基づいてレーザ光を発光するレーザ出力部（不図示）と、レーザ光を反射するポリゴンミラー３ａと、レンズ３ｂと、ミラー３ｃとを有する。露光手段３は、このレーザ光が感光体ドラム１表面を照射することによって感光体ドラム１を露光し、露光部分の電荷を除去して静電潜像を形成するように構成されている。図１の装置においては、感光体ドラム１表面に形成される静電潜像は、原稿の画像に基づいて、イエロー、シアン、マゼンタ、ブラックの４色に色分解され、それぞれの色に対応した静電潜像が順次形成されるようになっている。
【０１２１】
現像装置４は、感光体ドラム１の回転方向（矢印Ｒ１方向）に沿って上流側から順にイエロートナー、シアントナー、マゼンタトナー、ブラックトナーの各色トナー（現像剤）を収納した現像器４Ｙ、４Ｃ、４Ｍ、４Ｂｋを備えている。各現像器４Ｙ、４Ｃ、４Ｍ、４Ｂｋは、それぞれ感光体ドラム１表面に形成された静電荷像を現像するためのトナーを有する現像剤を担持している現像スリーブ４ａを有し、静電荷像の現像に供せられる所定の色の現像器が偏心カム４ｂによって、択一的に感光体ドラム１表面に近接する現像位置に配置されている。現像スリーブ４ａに担持されている現像剤のトナーが静電荷像を現像し、顕像としてのトナー像（可視画像）を形成するように構成されている。現像に供せられる現像器以外の他の３色の現像器は、現像位置から退避するようになっている。
【０１２２】
転写装置５は、表面に記録材Ｐを担持する転写ドラム（記録材担持体）５ａ、感光体ドラム１上のトナー像を記録材Ｐに転写する転写帯電器（転写帯電手段）５ｂ、記録材Ｐを転写ドラム５ａに吸着させるための吸着帯電器５ｃとこれに対向する吸着ローラ５ｄ、内側帯電器５ｅ、外側帯電器５ｆを有し、矢印Ｒ５方向に回転駆動されるように軸支された転写ドラム５ａの周面開口域には誘電体からなる記録材担持シート５ｇが円筒状に一体的に張設されている。記録材担持シート５ｇは、ポリカーボネートフィルムの如き誘電体シートを使用している。転写装置５は、転写ドラム５ａ表面に記録材Ｐを吸着して担持するように構成されている。
【０１２３】
クリーニング器６は、記録材Ｐに転写されずに感光体ドラム１表面に残った残留トナーを掻き落とすクリーニングブレード６ａ、及び掻き落としたトナーを回収するクリーニング容器６ｂを備えている。
【０１２４】
前露光ランプ７は、一次帯電器２の上流側に隣接して配置され、クリーニング部６によって清掃された感光体ドラム１表面の不要な電荷を除去する。
【０１２５】
給紙搬送部８は、大きさの異なる記録材Ｐを積載収納する複数の給紙カセット８ａ、給紙カセット８ａ内の記録材Ｐを給紙する給紙ローラ８ｂ、多数の搬送ローラ、そしてレジストローラ８ｃ等を有し、所定の大きさの記録材Ｐを転写ドラム５ａに供給する。
【０１２６】
分離手段９は、トナー像が転写された後の記録材Ｐを転写ドラム５ａから分離するための分離帯電器９ａ、分離爪９ｂ、分離押し上げころ９ｃ等を有する。
【０１２７】
加熱加圧定着器１０は、内側にヒータを有する定着ローラ１０ａと、定着ローラ１０ａの下方に配置され、記録材Ｐを定着ローラ１０ａに押し付ける加圧ローラ１０ｂとを有する。
【０１２８】
排紙部１１は、加熱加圧定着器１０の下流側に配置された、搬送パス切替ガイド１１ａ、排出ローラ１１ｂ、排紙トレイ１１ｃ等を有する。また、搬送パス切替ガイド１１ａの下方には、１枚の記録材Ｐに対してその両面に画像形成を行うために搬送縦パス１１ｄ、反転パス１１ｅ、積載部材１１ｆ、中間トレイ１１ｇ、さらに搬送ローラ１１ｈ、１１ｉ、反転ローラ１１ｊ等が配置されている。
【０１２９】
また、感光体ドラム１周囲における、一次帯電器２と現像装置４との間には、感光体ドラム１表面の帯電電位を検出する電位センサＳ１が、また現像装置４と転写ドラム５ａとの間には、感光体ドラム１上のトナー像の濃度を検知する濃度センサＳ２が、それぞれ配置されている。
【０１３０】
続いて、リーダ部ＩＩについて説明する。
【０１３１】
プリンタ部Ｉの上方に配置されたリーダ部ＩＩは、原稿Ｄを載置する原稿台ガラス１２ａ、移動しながら原稿Ｄの画像面を露光走査する露光ランプ１２ｂ、原稿Ｄからの反射光をさらに反射させる複数のミラー１２ｃ、反射光を集光するレンズ１２ｄ、そしてレンズ１２ｄからの光に基づいてカラー色分解画像信号を形成するフルカラーセンサ１２ｅ等を有する。カラー色分解画像信号は、増幅回路（不図示）を経て、ビデオ処理ユニット（不図示）によって処理を施され、上述のプリンタ部Ｉに送出されるようになっている。
【０１３２】
次に、図１の構成の画像形成装置の動作を説明する。以下の説明においては、イエロー、シアン、マゼンタ、ブラックの順に４色フルカラー画像を形成するものとする。
【０１３３】
リーダ部ＩＩの原稿台ガラス１２ａに載置された原稿Ｄの画像は、露光ランプよって照射され、色分解されて先ずイエローの画像がフルカラーセンサ１２ｅによって読み取られ、所定の処理を施され画像信号としてプリンタ部Ｉに送られる。
【０１３４】
プリンタ部Ｉでは、感光体ドラム１が矢印Ｒ１方向に回転駆動され、一次帯電器２によって表面が均一に帯電される。上述のリーダ部ＩＩから送られてきた画像信号に基づいて、露光手段３のレーザ出力部からレーザ光が照射され、ポリゴンミラー３ａ等を介して帯電済みの感光体ドラム１表面を光像Ｅによって露光する。感光体ドラム１表面の露光を受けた部分は電荷が除去され、これによりイエロー現像器４Ｙが所定の現像位置に配置され、そのほかの現像器４Ｃ、４Ｍ、４Ｂｋは現像位置から退避される。感光体ドラム１上の静電荷像は、現像器４Ｙによってイエローのトナーが付着され、顕像化されてイエロートナー像となる。この感光体ドラム１上のイエロートナー像は、転写ドラム５ａに担持された記録材Ｐに転写される。記録材Ｐは、原稿画像に適した大きさの記録材Ｐが所定の給紙カセット８ａから給紙ローラ８ｂ、搬送ローラ、レジストローラ８ｃ等を介して所定のタイミングで転写ドラム５ａに巻き付くように吸着されて矢印Ｒ５方向に回転し、転写帯電器５ｂによって感光体ドラム１上のイエロートナー像が転写される。
【０１３５】
一方、イエロートナー像が転写された後の感光体ドラム１は、クリーニング器６によって表面の残留トナーが除去され、さらに前露光ランプ７によって不要な電荷が除去され、一次帯電から始まる次の画像形成に供される。
【０１３６】
以上のリーダ部ＩＩによる原稿画像の読み取りから、転写ドラム５ａ上の記録材Ｐに対するトナー像の転写、さらには感光体ドラム１の清掃、除電に至る各プロセスが、イエロー以外の他の色、即ち、シアン、マゼンタ、ブラックについても同様に行われ、転写ドラム５ａ上の記録材Ｐには、イエロートナー、シアントナー、マゼンタトナー及びブラックトナーの４色のトナー像が重なるようにして転写される。
【０１３７】
４色のトナー像の転写を受けた記録材Ｐは、分離帯電器９ａ、分離爪９ｂ等によって転写ドラム５ａから分離され、未定着のトナー像を表面に担持した状態で定着器１０に搬送される。記録材Ｐは、加熱加圧定着器１０の定着ローラ１０ａ及び加圧ローラ１０ｂによって加熱加圧され、カラートナー像が溶融されて定着され、フルカラー画像が記録材Ｐの一方の面に形成される。定着後の記録材Ｐは、排出ローラ１１ｂによって排紙トレイ１１ｃ上に排出される。
【０１３８】
次に、図１の加熱加圧定着器１０の拡大図を図２に示して当該定着器について説明する。
【０１３９】
図２において、トナー像と接触する定着ローラ１０ａは、例えば、アルミニウム製の芯金３１上の１ｍｍ厚のＨＴＶ（高温加硫型）シリコーンゴム層３２、この外側に特定の付加型シリコーンゴム層３３を有し、直径６０ｍｍに形成されている。
【０１４０】
一方、加圧ローラ１０ｂは、例えば、アルミニウム製の芯金３４上に、１ｍｍ厚のＨＴＶと、さらに厚さ１ｍｍの前述の特定の付加型シリコーンゴム層３５を設け、直径６０ｍｍに形成されている。
【０１４１】
上述の定着ローラ１０ａには、発熱手段である搬送ローラヒータ３６が芯金３１内に配設され、加圧ローラ１０ｂには、同じくヒータ３７が芯金３４内に配設されて記録材Ｐの両面から加熱を行っている。加圧ローラ１０ｂに当接されたサーミスタ３８によって加圧ローラ１０ｂの温度が検知され、この検知温度に基づいて制御装置３９によりハロンゲンヒータ３６、３７が制御され、定着ローラ１０ａ及び加圧ローラ１０ｂの温度が共に所定の温度に一定に維持されるように制御される。尚、定着ローラ１０ａと加圧ローラ１０ｂとは、加圧機構（不図示）によって所定の圧力で加圧されている。
【０１４２】
また、図２においては、Ｏはオイル塗布装置であり、Ｃはクリーニング装置であり、Ｃ１は加圧ローラ１０ｂのオイル汚れを除去するクリーニングブレードである。オイル塗布装置Ｏは、オイルパン４０内のジメチルシリコーンオイル４１をオイル汲み上げローラ５０、４２及びオイル塗布ローラ４３を経由させてオイル塗布量調整ブレード４４でオイル塗布量を規制して定着ローラ１０ａに当接されたウエブ４６によって定着ローラ１０ａ表面を清掃する。
【０１４３】
上述の定着装置１０では、未定着トナー像を表面に担持した記録材Ｐは、定着ローラ１０ａと加圧ローラ１０ｂとの間の定着ニップに挟持搬送され、このとき、表裏両面から加熱加圧されてトナーの定着が行われる。この際、定着ローラ１０ａ、加圧ローラ１０ｂに付着したトナーは、それぞれクリーニング装置Ｃ、クリーニングブレードＣ１によって除去される。
【０１４４】
以上、記録材の一方の面にのみフルカラー画像を形成する方法について説明したが、次にこのフルカラー画像を記録材の両面に形成する方法について説明する。
【０１４５】
記録材Ｐの両面にフルカラー画像を形成する場合は、加熱加圧定着器１０は排出後の記録材Ｐを、すぐに搬送パス切替ガイド１１ａを駆動し、搬送パス１１ｄを経て、反転パス１１ｅに一旦導いた後、反転ローラ１１ｊの逆転により、送り込まれた際の後端を先頭にして、送り込まれた方向と反対向きに退出させ、中間トレイ１１ｇに収納する。その後、中間トレイ１１ｇの一方の面にフルカラー画像を有する記録材Ｐは転写ドラム５ａに送られ、他方の面に再度上述の画像形成プロセスによりイエロートナー、シアントナー及びマゼンタトナーのカラートナーが転写され、さらにブラックトナーが転写される。記録材Ｐのフルカラー画像が転写ドラム５ａに接触するので、定着時にフルカラー画像面に付着したシリコーンオイルが転写ドラム５ａに付着し、転写工程を通常に阻害しやすいが、本発明のブラックトナーは、シリコーンオイルの吸収性に優れているので、転写ドラム５ａに付着するシリコーンオイル量が従来と比較して極めて少ない。
【０１４６】
他方の面に未定着のカラートナー画像を有する記録材Ｐは、転写ドラム５ａから分離され、加熱加圧定着器１０へ送られ、未定着のカラートナー像は、記録材Ｐの他方の面に加熱加圧定着され、記録材Ｐの両面にフルカラー画像が形成される。その際、本発明のブラックトナーは、カーボンブラックが良好に分散され、適量の離型剤が含有されているため、両面に良好に画像が形成され、定着ローラ１０ａ及び加圧ローラ１０ｂへの記録材Ｐの巻き付きが抑制され、オフセット現象の発生も良好に防止されるものである。
【０１４７】
本発明のブラックトナーを使用すると、転写ドラム５ａの記録材担持シート５ｇのシリコーンオイル等の汚染は従来と比較して極めて少ないが、必要に応じてファーブラシ１３ａとバックアップブラシ１３ｂ及びオイル除去ローラ１４ａとバックアップブラシ１４ｂによって清掃を行う。このような清掃は、必要に応じて画像形成前もしくは画像形成後に行い、また、ジャム（紙詰まり）発生した場合には随時行う。
【０１４８】
次に、各物性の測定方法について説明する。
【０１４９】
〔ウルトラマリンの体積平均粒径の測定方法〕
レーザ回折／散乱式粒度分布測定装置（ホリバ社製「ＬＡ−９２０」）を用いて測定する。
【０１５０】
〔吸油量の測定方法〕
ウルトラマリンの吸油量はＪＩＳ Ｋ５１０１−２１により、カーボンブラックの吸油量はＪＩＳ Ｋ６２２１ Ａ法により測定する。
【０１５１】
〔ｐＨの測定方法〕
ウルトラマリンのｐＨはＪＩＳ Ｋ５１０１−２６により、カーボンブラックのｐＨはＤＩＮ ＩＳＯ ７８７／９により測定する。
【０１５２】
〔トナーの粘弾性の測定方法〕
トナーを直径８ｍｍ、厚さ約２〜３ｍｍの円板状の試料に加圧成形する。次にパラレルプレートにセットし、５０〜２００℃の温度範囲内で徐々に昇温させ、温度分散測定を行う。昇温速度は２℃／ｍｉｎとし、角周波数（ω）は６．２８ｒａｄ／ｓｅｃに固定し、歪率は自動とする。横軸に温度、縦軸に貯蔵弾性率（Ｇ’）、損失弾性率弾性率（Ｇ”）を取り、各温度における値を読み取る。測定にあたっては、ＲＤＡ‐ＩＩ（レオメトリックス社製）を用いる。
【０１５３】
〔トナーの誘電正接の測定方法〕
４２８４ＡプレシジョンＬＣＲメーター（ヒューレット・パッカード社製）を用いて、１ｋＨｚ及び１ＭＨｚの周波数で校正後、周波数５×１０^４Ｈｚと１×１０^５Ｈｚの誘電率の測定値から誘電正接（ｔａｎδε）を算出する。
【０１５４】
トナー０．５〜０．７ｇを秤量し、３４３００ｋＰａ（３５０ｋｇｆ／ｃｍ^２）の荷重を２分間かけて、直径２５ｍｍ、厚さ１ｍｍ以下（好ましくは、０．５〜０．９ｍｍ）の円盤状に成型し、測定試料とする。この測定試料を直径２５ｍｍの誘電率測定治具（電極）を装着したＡＲＥＳ（レオメトリック・サイエンティフィック・エフ・イー社製）に装着し、固定する。その後、３．４３Ｎ（３５０ｇ）の荷重をかけた状態で、１００〜１０^６Ｈｚの周波数範囲で３回測定し、平均値を算出する。
【０１５５】
〔トナーの吸熱ピークの測定方法〕
示差走査熱量計（ＤＳＣ測定装置）、ＤＳＣ−７（パーキンエルマー社製）を用いてＡＳＴＭ Ｄ３４１８−８２に準じて測定する。
【０１５６】
測定試料は５〜２０ｍｇ、好ましくは１０ｍｇを精密に秤量する。
【０１５７】
これをアルミパン中に入れ、リファレンスとして空のアルミパンを用い、測定温度範囲３０〜２００℃の間で、昇温速度１０℃／ｍｉｎで常温常湿下で測定を行う。この昇温過程で、温度３０〜２００℃の範囲におけるＤＳＣ曲線のメインピークの吸熱ピークが得られる。
【０１５８】
〔ＧＰＣによる分子量分布の測定方法〕
ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によるクロマトグラムの分子量は次の条件で測定される。４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに溶媒としてテトラヒドロフラン（ＴＨＦ）を毎分１ｍｌの流速で流し、試料濃度として０．０５〜０．６質量％に調整した樹脂のＴＨＦ試料溶液を約５０〜２００μｌ注入して測定する。試料の分子量測定にあたっては、試料の有する分子量分布を数種の単分散ポリスチレン標準試料により作成された検量線の対数値とカウント数（リテンションタイム）との関係から算出する。検量線作成用の標準ポリスチレン試料としては、例えば東ソー社製或いはＰｒｅｓｓｕｒｅ Ｃｈｅｍｉｃａｌ Ｃｏ．製の分子量が６×１０^２、２．１×１０^３、４×１０^３、１．７５×１０^４、５．１×１０^４、１．１×１０^５、３．９×１０^５、８．６×１０^５、２×１０^６、４．４８×１０^６のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。検出器にはＲＩ（屈折率）検出器を用いる。
【０１５９】
カラムとしては、１０^３〜２×１０^６の分子量領域を的確に測定するために、市販のポリスチレンジェルカラムを複数本組み合わせるのが良く、例えば昭和電工社製のｓｈｏｄｅｘ ＧＰＣ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７の組み合わせや、Ｗａｔｅｒｓ社製のμ−ｓｔｙｒａｇｅｌ ５００、１０^３、１０^４、１０^５の組み合わせを挙げることができる。
【０１６０】
〔トナーの粒度分布の測定方法〕
本発明において、トナーの平均粒径及び粒度分布はコールターカウンターＴＡ−ＩＩ型（コールター社製）を用いて行うが、コールターマルチサイザー（コールター社製）を用いることも可能である。電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。例えば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜５ｍｌ加え、さらに測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行い、前記測定装置によりアパチャーとして１００μｍアパチャーを用いて、２．００μｍ以上のトナーの体積、個数を測定して体積分布と個数分布とを算出した。それから本発明に係る体積分布から求めた重量基準の重量平均粒径（Ｄ４）（各チャンネルの中央値をチャンネル毎の代表値とする）を求めた。
【０１６１】
チャンネルとしては、２．００〜２．５２μｍ；２．５２〜３．１７μｍ；３．１７〜４．００μｍ；４．００〜５．０４μｍ；５．０４〜６．３５μｍ；６．３５〜８．００μｍ；８．００〜１０．０８μｍ；１０．０８〜１２．７０μｍ；１２．７０〜１６．００μｍ；１６．００〜２０．２０μｍ；２０．２０〜２５．４０μｍ；２５．４０〜３２．００μｍ；３２．００〜４０．３０μｍの１３チャンネルを用いる。
【０１６２】
〔カーボンブラックの平均一次粒径の測定方法〕
本発明においては、トナー中のカーボンブラックの平均一次粒径は、次のようにして測定した。
【０１６３】
紫外線硬化型のアクリル樹脂中にトナーを十分に分散させた後、紫外線を照射して硬化させ、得られた硬化物をウルトラミクロトームを用いて面出しし、それを四酸化ルテニウム（ＲｕＯ_４）、または必要に応じて四酸化オスミウム（ＯｓＯ_４）を併用して電子染色を施した後、ダイヤモンドナイフを備えたウルトラミクロトームを用いて薄片状のサンプルを切り出し、透過型電子顕微鏡（ＴＥＭ）を用いてトナーの断面層形態を観察した。こうして得られたトナーの断面写真（例えば、４万倍に拡大した断面写真）より、凝集体を形成していないカーボンブラックについて、無作為に抽出し、解析を行うこととし、サンプリング数が３００回を超えるまで測定を繰り返して平均粒径を求めた。
【０１６４】
本発明では、画像処理装置を用いてカーボンブラックを球形近似し、得られる直径より定義される値をカーボンブラックの平均一次粒径（Ａ）とした。また、ＴＥＭ写真より直接カーボンブラックの平均一次粒径を測定する際には、カーボンブラックの長径を粒径とし、同じくサンプリング数が３００回を超えるまで測定を繰り返して平均一次粒径（Ｂ）を求めた。本発明では、上記の（Ａ）も（Ｂ）もほぼ同じ結果が得られた。
【０１６５】
以下に本発明の実施態様を示す。
【０１６６】
〔実施態様１〕
少なくとも結着樹脂と、離型剤と、結着樹脂１００質量部当たり０．５〜１０質量部のカーボンブラックと、体積平均粒径が０．３〜３．０μｍのウルトラマリンを含有することを特徴とするブラックトナーである。
【０１６７】
〔実施態様２〕
実施態様１において、ウルトラマリンを結着樹脂１００質量部当たり０．０１〜２質量部含有する。
【０１６８】
〔実施態様３〕
実施態様１または２において、トナーの８０℃における貯蔵弾性率（Ｇ’_８０）が１×１０^６〜１×１０^８［ｄＮ／ｍ^２］の範囲にあり、温度１４０℃における貯蔵弾性率（Ｇ’）及び損失弾性率（Ｇ”）の比（Ｇ”／Ｇ’）で示される損失正接（ｔａｎδ_Ｇ）が０．２〜１．５の範囲にあり、誘電損率（ε”）と誘電率（ε’）の比（ε”／ε’）で示される損失正接（ｔａｎδ_ε）が、
周波数５×１０^４Ｈｚにおいて、ｔａｎδ_ε（５×１０^４Ｈｚ）≦０．００８
周波数１×１０^５Ｈｚにおいて、ｔａｎδ_ε（１×１０^５Ｈｚ）≦０．０１１
であることを特徴とする請求項１または２に記載のブラックトナー。
【０１６９】
〔実施態様４〕
実施態様１〜３のいずれかにおいて、トナーが、示差熱分析（ＤＳＣ）測定における吸熱曲線において、温度３０〜２００℃の範囲に１個または複数の吸熱ピークを有し、該吸熱ピーク中の最大吸熱ピークのピーク温度が６０〜１１０℃の範囲にある。
【０１７０】
〔実施態様５〕
実施態様１〜４のいずれかにおいて、結着樹脂が、
（ａ）ポリエステル樹脂、
（ｂ）ポリエステルユニットとビニル系重合体ユニットを有しているハイブリッド樹脂、
（ｃ）上記（ｂ）のハイブリッド樹脂とビニル系重合体との混合物、
（ｄ）ポリエステル樹脂とビニル系重合体との混合物、
（ｅ）上記（ｂ）のハイブリッド樹脂とポリエステル樹脂との混合物
のいずれかから選択される樹脂である。
【０１７１】
〔実施態様６〕
実施態様１〜５のいずれかにおいて、離型剤が、トナー中の樹脂成分１００質量部に対して１〜２０質量部含有されている。
【０１７２】
〔実施態様７〕
実施態様１〜６のいずれかにおいて、トナーの重量平均粒径が４〜１０μｍである。
【０１７３】
【実施例】
以下、本発明の実施例について説明するが、本発明がこれら実施例に限定されるものではない。
【０１７４】
〔ウルトラマリン〕
本実施例で用いたウルトラマリンを表１に示す。
【０１７５】
【表１】

【０１７６】
〔ハイブリッド樹脂の製造〕
ビニル系モノマー組成物として、
スチレン １．９モル
２−エチルヘキシルアクリレート ０．２１モル
フマル酸 ０．１５モル
α−メチルスチレンの二量体 ０．０３モル
ジクミルパーオキサイド ０．０５モル
を滴下ロートに入れた。また、
ポリオキシプロピレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プ
ロパン ７．０モル
ポリオキシエチレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プロ
パン ３．０モル
テレフタル酸 ３．０モル
無水トリメリット酸 ２．０モル
フマル酸 ５．０モル
酸化ジブチル錫 ０．２ｇ
をガラス製４リットルの四つ口フラスコに入れ、温度計、攪拌棒、コンデンサ及び窒素導入管を取り付けマントルヒーター内に置いた。次に、フラスコ内を窒素ガスで置換した後、攪拌しながら徐々に昇温し、１４５℃の温度で攪拌しつつ、先の滴下ロートよりビニル系モノマー組成物を４時間かけて滴下した。次いで、２００℃に昇温し、４時間反応させてハイブリッド樹脂を得た。ＧＰＣによる分子量測定の結果を表２に示す。
【０１７７】
〔ポリエステル樹脂の製造〕
ポリオキシプロピレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プ
ロパン ３．６モル
ポリオキシエチレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プロ
パン １．６モル
テレフタル酸 １．７モル
無水トリメリット酸 １．１モル
フマル酸 ２．４モル
酸化ジブチル錫 ０．１ｇ
をガラス製４リットルの四つ口フラスコに入れ、温度計、攪拌棒、コンデンサ及び窒素導入管を取り付けマントルヒーター内に置いた。窒素雰囲気下で、２１５℃で５時間反応させ、ポリエステル樹脂を得た。ＧＰＣによる分子量測定の結果を表２に示す。
【０１７８】
〔ビニル系重合体の製造〕
スチレン ２．２モル
２−エチルヘキシルアクリレート ０．２３モル
ジクミルパーオキサイド ０．０８モル
酸化ジブチル錫 ３．２ｇ
を、温度計、ステンレス製攪拌棒、流下式コンデンサ及び窒素導入管を装備した３リットルの四つ口フラスコに入れ、マントルヒーター中で、窒素雰囲気にて２２５℃で攪拌しつつ反応させ、ビニル系重合体を得た。ＧＰＣによる分子量測定の結果を表２に示す。
【０１７９】
【表２】

【０１８０】
〔離型剤〕
本実施例では、離型剤として、融点６７．２℃の精製ｎ−パラフィンワックスを用いた。
【０１８１】
〔カーボンブラック〕
本実施例に用いたカーボンブラックを表３に示す。
【０１８２】
【表３】

【０１８３】
〔トナー及び現像剤の製造〕
表４に示すトナー材料をヘンシェルミキサーにより十分予備混合した後、二軸式押出機で溶融混練し、冷却後ハンマーミルを用いて粒径約１〜２ｍｍ程度に素粉砕した。次いで、エアージェット方式による微粉砕機で微粉砕した。さらに、得られた微粉砕物を多分割分級装置で分級して、重量平均粒径が７．０μｍのトナー粒子を得た。
【０１８４】
上記トナー粒子１００質量部に対して、ｎ−Ｃ_４Ｈ_９Ｓｉ（ＯＣＨ_３）_３で処理した疎水性酸化チタン（ＢＥＴ比表面積：１１０ｍ^２／ｇ）１．０質量部を合わせてトナーとした。さらに、該トナーと、シリコーン樹脂で表面被覆した磁性フェライトキャリア粒子（平均粒径：５０μｍ）とを、トナー濃度が６質量％となるように混合し、二成分系現像剤とした。
【０１８５】
【表４】

【０１８６】
〔評価方法〕
市販の普通紙フルカラー複写機（キヤノン製「ＣＬＣ９００」）を用い、常温常湿下（２３℃／６０％）で、画像面積比率２５％のオリジナル原稿を用いて、連続複写２万枚の耐久試験を行った。
【０１８７】
▲１▼現像性（画像濃度）
現像性は耐久初期と２万枚耐久後の画像濃度の変化を評価の基準とした。画像濃度は、マクベス社製のマクベス濃度計にてオリジナル画像のベタ部（単位面積当たりのトナー載り量：０．６ｍｇ／ｃｍ^２に設定）を５回平均し、画像濃度の変化値を見た。
【０１８８】
▲２▼カブリ
白地部分の白色度をリフレクトメーター（東京電色社製）により測定し、その白色度と転写紙の白色度の差からカブリ濃度（％）を算出し、評価した。評価基準は以下の通りである。
Ａ：非常に良好（１．０％未満）
Ｂ：良好（１．０％〜２．０％未満）
Ｃ：普通（２．０％〜３．０％未満）
Ｄ：悪い（３．０％以上）
【０１８９】
▲３▼定着温度幅
カラー複写機（キヤノン製「ＣＬＣ９００」）のオイル塗布機構を取り外し、さらに、定着温度を自由に設定できるように改造して定着試験を行った。このときの画像面積比率は２５％であり、単位面積当たりのトナー載り量は０．６ｍｇ／ｃｍ^２に設定した。定着開始温度とオフセット発生温度の測定は、定着器の設定温度を１２０〜２１０℃の温度範囲で５℃おきに温度調節して、各温度で定着画像を出力し、得られた定着画像を４．９ｋＰａ（５０ｇ／ｃｍ^２）の荷重をかけたシルボン紙で摺擦し、摺擦前後の濃度低下率が１０％以下となる定着温度を定着開始温度とした。また、定着開始温度からさらに設定温度を上げてゆき、目視で高温オフセットの発生した温度をオフセット発生温度とした。
【０１９０】
▲４▼保存性（耐ブロッキング性）
５０℃のオーブン内にて１週間トナーを放置し、目視により凝集性のレベルを判定した。評価基準を以下に示す。
Ａ：凝集体が全く見られず、流動性が非常によい。
Ｂ：若干の凝集体は見られるが、すぐにほぐれる。
Ｃ：現像剤撹拌装置で凝集体がほぐれる（普通）。
Ｄ：現像剤撹拌装置では凝集体がほぐれない（やや悪い）。
【０１９１】
（実施例１〜８）
２００００枚の耐久後も非常に良好な現像性を示し、カブリも発生しなかった。また、低温定着性、耐高温オフセット性にも優れ、広い定着温度幅をとることができた。結果を表５に示す。
【０１９２】
（実施例９、１０）
実施例１に比較して、定着開始温度が若干高くなったが、使用上問題はなかった。また、実施例９では、保存性が若干不利であったが、問題のないレベルであった。結果を表５に示す。
【０１９３】
（実施例１１）
２００００枚の耐久後も非常に良好な現像性を示し、カブリも発生しなかった。また、低温定着性、耐高温オフセット性にも優れ、広い定着温度幅をとることができた。結果を表５に示す。
【０１９４】
（実施例１２）
実施例１に比較すると、カーボンブラック量が少ないため、画像濃度が低かったが、良好な現像性を示し、カブリも発生せず、使用上問題はなかった。結果を表５に示す。
【０１９５】
（実施例１３）
実施例１に比較すると、カーボンブラックの量が多く、ｔａｎδ_εの値が若干悪くなったが、良好な画像が得られた。結果を表５に示す。
【０１９６】
（実施例１４）
実施例１に比較すると、ワックス量が少ないためか、定着温度幅が若干狭くなった。結果を表５に示す。
【０１９７】
（実施例１５）
実施例１に比較すると、カブリと保存性が若干悪くなり、得られた画像はわずかに赤みを帯びていたが、使用上問題はなかった。結果を表５に示す。
【０１９８】
（実施例１６）
実施例１に比較すると、カブリが若干悪く、画像濃度も低かったが、使用上問題はなかった。結果を表５に示す。
【０１９９】
（実施例１７）
実施例１に比較すると、カブリが若干悪く、画像濃度も低かったが、使用上問題はなかった。結果を表５に示す。
【０２００】
（比較例１）
用いたウルトラマリンの粒径が小さく、成分であるイオウが遊離していると思われ、耐久後、画像濃度の低下やカブリが発生した。結果を表５に示す。
【０２０１】
（比較例２）
用いたウルトラマリンの粒径が大きく、ふるい残分も多いため、凝集が起こっていると思われ、ｔａｎδ_εの値が悪くなり、カブリも発生した。結果を表５に示す。
【０２０２】
（比較例３）
カーボンブラックの添加量が少なかったため、十分な画像濃度を得ることができなかった。結果を表５に示す。
【０２０３】
（比較例４）
カーボンブラックの添加量が多すぎたため、カブリが著しく、耐久後の画像濃度が低下した。結果を表５に示す。
【０２０４】
（比較例５）
低軟化点物質を用いていないため、記録材の定着ローラへの巻き付きが起こった。結果を表５に示す。
【０２０５】
（比較例６）
ウルトラマリンを使用しなかったため、カーボンブラックの分散性が悪く、ｔａｎδ_ε値が悪く、画像濃度、カブリ、定着温度幅の全てにおいて良好な結果が得られなかった。結果を表５に示す。
【０２０６】
【表５】

【０２０７】
【発明の効果】
以上説明したように、本発明においては、ウルトラマリンの添加によってカーボンブラック及び離型剤の分散性に優れるため、低濃度から高濃度までダイナミックレンジをカバーする高着色力を有し、定着性、保存安定性、耐熱性に優れたトナーが提供される。
【図面の簡単な説明】
【図１】本発明のトナーを適用しうる画像形成装置の一例の概略構成図である。
【図２】図１の画像形成装置の加熱定着器の拡大図である。
【符号の説明】
１ 感光体ドラム
１ａ 基体
１ｂ 感光体
２ 一次帯電器（帯電手段）
２ａ シールド
２ｂ 放電ワイヤ
２ｃ グリッド
３ 露光手段
３ａ ポリゴンミラー
３ｂ レンズ
３ｃ ミラー
４ 現像装置（現像手段）
４Ｙ、４Ｃ、４Ｍ、４Ｂｋ 現像器
４ａ 現像スリーブ
４ｂ 偏心カム
５ 転写装置
５ａ 転写ドラム（記録材担持体）
５ｂ 転写帯電器（転写帯電手段）
５ｃ 吸着帯電器
５ｄ 吸着ローラ
５ｅ 内側帯電器
５ｆ 外側帯電器
５ｇ 記録材担持シート
６ クリーニング器
６ａ クリーニングブレード
６ｂ クリーニング容器
７ 前露光ランプ
８ 給紙搬送部
８ａ 給紙カセット
８ｂ 給紙ローラ
８ｃ レジストローラ
９ 分離手段
９ａ 分離帯電器
９ｂ 分離爪
９ｃ 分離ころ
１０ 加熱加圧定着器
１０ａ 定着ローラ
１０ｂ 加圧ローラ
１１ 排紙部
１１ａ 搬送パス切替ガイド
１１ｂ 排出ローラ
１１ｃ 排紙トレイ
１１ｄ 搬送縦パス
１１ｅ 反転パス
１１ｆ 積載部材
１１ｇ 中間トレイ
１１ｈ 搬送ローラ
１１ｊ 反転ローラ
１２ａ 原稿台ガラス
１２ｂ 露光ランプ
１２ｃ ミラー
１２ｄ 集光レンズ
１２ｅ フルカラーセンサ
１３ａ ファーブラシ
１３ｂ、１４ｂ バックアップブラシ
１４ａ オイル除去ローラ
３１、３４ 芯金
３２ ＨＴＶシリコーンゴム層
３３ 付加型シリコーンゴム層
３６、３７ ハロゲンヒータ
３８ サーミスタ
３９ 制御装置
４０ オイルパン
４１ ジメチルシリコーンオイル
４２、５０ オイル汲み上げローラ
４３ オイル塗布ローラ
４４ オイル塗布量調整ブレード
４５ 突当ローラ
４６ ウエブ
Ｉ プリンタ部
ＩＩ リーダ部
Ｃ クリーニング装置
Ｃ１ クリーニングブレード
Ｄ 原稿
Ｅ 光像
Ｏ オイル塗布装置
Ｐ 記録材
Ｓ１ 電位センサ
Ｓ２ 濃度センサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a black toner for developing an electrostatic image or a black toner of a toner jet system, and does not use oil for preventing high-temperature offset, or uses a heat and pressure fixing unit with a reduced amount of oil. Also relates to a black toner that can be sufficiently fixed.
[0002]
[Prior art]
In recent years, a full-color copying machine that has been proposed uses four photoconductors and a belt-shaped transfer body, and uses a cyan toner, a magenta toner, a yellow toner, and a black toner to form an electrostatic charge image formed on each photoconductor. After transferring and transferring the transfer material (recording material) between the photoreceptor and the belt transfer member and transferring it between straight passes, a full-color image is formed, or the electrostatic force is applied to the surface of the transfer member facing the photoreceptor. Generally, a method is used in which a transfer material is wound by a mechanical action such as a gripper or a gripper and a development-transfer process is performed four times to obtain a full-color image.
[0003]
The toner applied to these full-color copiers is that the respective toners are sufficiently mixed in the heating and pressing fixing step without increasing the color reproducibility and losing the transparency (OHP transparency) of the overhead projector (OHP) image. is necessary. Compared with a general black toner for a black-and-white copying machine, the toner for forming a full-color image is preferably a low-molecular-weight binder resin having sharp melt properties. However, when a sharp-melting binder resin is used, the self-cohesive force of the binder resin is low when the toner is melted in the heating and pressurizing fixing step, so that a problem is likely to occur in the hot offset resistance. Therefore, as proposed in, for example, Patent Documents 1 to 3, in general black toners for black-and-white copying machines, relatively high crystallinity represented by polyethylene wax or polypropylene wax is used in order to improve high-temperature offset resistance during fixing. Wax is used as a release agent.
[0004]
Further, there has been proposed a toner having a specific storage modulus in order to improve the offset resistance. For example, Patent Documents 4 and 5 propose a toner having a specific storage modulus at 180 ° C. or 170 ° C. However, as a toner for forming a full-color image that requires compatibility between low-temperature fixing and high-temperature offset resistance, sufficient color mixing characteristics, and the like, the viscosity of the toner is too low and the storage stability in a high-temperature, high-humidity environment is satisfactory. I couldn't do it.
[0005]
Further, Patent Documents 6 to 12 also propose a toner having a specific storage modulus. However, there is still room for improvement in securing ideal fixing characteristics as a toner for full-color image formation and stably fixing the toner even in long-term durability.
[0006]
For this reason, in a normal full-color image forming toner, an oil such as silicone oil or fluorine oil is applied to the heat fixing roller to improve the hot offset resistance. However, the fixed image thus obtained had extra oil adhered to the surface, and had image defects characteristic of oil application, such as uneven application and glare of the oil. On the other hand, at the time of double-sided fixing, oil on the surface of the first image which has already been fixed adheres to the photoreceptor, causing a new image defect. In addition, it has been pointed out that oil swells the fixing roller and shortens the life of the fixing roller. In this method, it is necessary to supply oil uniformly and quantitatively to the surface of the fixing roller in order to prevent generation of oil streaks on the fixed image, and the fixing device tends to be large.
[0007]
Therefore, in the heating and pressurizing fixing means in which no oil is used or the amount of used oil is reduced, the expectation of the toner in which the occurrence of the offset is suppressed is great, and it is strongly expected that the toner is excellent in the low-temperature fixing property. It was long-awaited.
[0008]
On the other hand, when carbon black is used as a coloring agent, many problems tend to occur more easily than a color toner using a normal organic pigment as a coloring agent. For example, since carbon black generally has a small primary particle size and a large specific surface area, it is difficult to uniformly disperse it in a toner, and free carbon black is easily generated. Therefore, sufficient charging cannot be performed, and problems such as toner scattering and fogging are likely to occur. In addition, loose carbon black tends to cause problems such as sleeve contamination, carrier spent, and drum filming, and it has been difficult to stabilize long-term durability. Further, since carbon black is generally conductive, the chargeability of the toner is hindered, and uniform charging cannot be performed, so that uniformity in a halftone image area is reduced or uniform transferability during transfer is deteriorated. There was a problem.
[0009]
In order to solve these problems, for example, Patent Document 13 discloses a method using carbon black having a surface grafted, and Patent Document 14 discloses a method using carbon black surface-treated with an aluminum coupling agent. Although these methods have been proposed, the steps for surface-treating carbon black are complicated and time-consuming, and the production cost is required to be increased, so that it is difficult to employ them industrially.
[0010]
Regarding the improvement of the dispersibility of carbon black, Patent Documents 15 and 16 propose a method of improving the dispersibility by using a specific dispersant, but it cannot be said that this method has been sufficiently solved. The situation.
[0011]
Patent Document 17 proposes a black toner composed of carbon black having a relatively high oil absorption and an azo iron compound having a specific structure. Although this is a toner having a high coloring power and a stable charging property, it still leaves some problems in solid uniformity and durability under a high humidity environment.
[0012]
[Patent Document 1]
Japanese Patent Publication No. 52-3304
[Patent Document 2]
Japanese Patent Publication No. 52-3305
[Patent Document 3]
JP-A-57-52574
[Patent Document 4]
JP-A-11-84716
[Patent Document 5]
JP-A-8-54750
[Patent Document 6]
JP-A-5-249735
[Patent Document 7]
JP-A-7-92737
[Patent Document 8]
JP-A-7-234542
[Patent Document 9]
JP-A-7-295298
[Patent Document 10]
JP-A-8-234480
[Patent Document 11]
JP-A-8-278662
[Patent Document 12]
JP-A-10-171156
[Patent Document 13]
JP-A-56-116044
[Patent Document 14]
JP-A-63-210849
[Patent Document 15]
JP-A-64-35457
[Patent Document 16]
JP-A-1-145664
[Patent Document 17]
JP-A-10-186713
[0013]
[Problems to be solved by the invention]
An object of the present invention is to provide a black toner which has solved the above-mentioned problems.
[0014]
That is, the present invention provides a black toner having excellent dispersibility of carbon black and a release agent and having high coloring power covering a wide dynamic range from low to high concentrations.
[0015]
Another object of the present invention is to provide a black toner in which the occurrence of offset is suppressed in a heating / pressing fixing unit using no oil or using a small amount of oil.
[0016]
It is a further object of the present invention to provide a black toner having excellent low-temperature fixability.
[0017]
Still another object of the present invention is to provide a black toner having excellent storage stability, heat resistance and blocking resistance.
[0018]
Further, an object of the present invention is to provide a black toner which is free from fog, has excellent highlight reproducibility, has excellent solid uniformity, and has excellent durability stability.
[0019]
[Means for Solving the Problems]
The present invention provides at least a binder resin, a release agent, 0.5 to 10 parts by mass of carbon black per 100 parts by mass of the binder resin, and ultramarine having a volume average particle diameter of 0.3 to 3.0 μm. It is a black toner characterized by containing.
[0020]
As a result of intensive studies, the present inventors have found the following in a black toner containing ultramarine.
[0021]
By appropriately adding ultramarine, the dispersibility of the carbon black is improved, the dispersibility of the release agent is also improved, the charge stability is improved, and excellent image quality and durability are provided. Further, it has been found that ultramarine has a bluing (increase in blackness) effect as an additive and has high coloring power.
[0022]
That is, a toner having excellent coloring power and charging performance as compared with a conventional toner containing carbon black can be obtained. In addition, the heat and pressure fixing means that uses no oil or uses less oil has excellent high-temperature offset resistance, and achieves both long-term storage stability and low-temperature fixability in a high-temperature environment. Is what I was able to do.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the toner of the present invention will be described in detail.
[0024]
The black toner of the present invention contains at least a binder resin, a release agent, carbon black, and ultramarine.
[0025]
According to detailed studies by the present inventors, by appropriately including ultramarine in the toner, the dispersibility of carbon black is improved, and the decrease in toner resistance due to the conductivity of carbon black is sufficiently suppressed. can do. By these actions, it is possible to provide a toner having high coloring power and quick and good chargeability in any environment.
[0026]
The reason for this is not clearly understood, but is considered as follows.
[0027]
Due to the effect of the functional group present on the surface of the binder resin of the toner, carbon black, which is usually hydrophobic, has a low affinity for the binder resin and is difficult to disperse. In addition, the fact that carbon black has a small particle size and a structure in which carbon is arranged in a network form also causes a decrease in affinity for the binder resin. However, by including ultramarine as in the present invention, ultramarine acts as a buffer between the binder resin and the carbon black, and the affinity between the binder resin and the carbon black increases.
[0028]
This is considered to be because ultramarine is an inorganic pigment that is structurally similar to zeolite, and has high dispersibility in oil-based materials in addition to the inherent hydrophilicity.
[0029]
Therefore, the carbon black is present in a state of being wrapped with the binder resin, and the dispersibility in the toner particles is increased, so that the uneven distribution of the carbon black on the toner surface can be suppressed, and the release of the carbon black can be prevented. Can be suppressed. In addition, even if there is carbon black on the toner particle surface, it is covered with the binder resin, preventing the charge from leaking and suppressing the increase in the conductivity of the toner particles. It becomes. As a result, a toner having quick and good chargeability can be obtained.
[0030]
Furthermore, due to the buffering action of Ultramarine, not only carbon black, but also the dispersibility of the release agent is improved, which not only improves the aforementioned coloring power and chargeability, but also improves the transferability and the fluidity of the toner. The finding that it is improved was obtained.
[0031]
As a result, high uniform charging with the charging member was achieved, and an image having excellent halftone reproducibility in a color image could be obtained.
[0032]
Next, the ultramarine used in the present invention will be described.
[0033]
Ultramarine used in the present invention is generally composed of a raw material mainly comprising kaolin, soda ash, sulfur, and a reducing agent, and can be obtained through processes such as firing, grinding, drying, and surface processing. Is not limited.
[0034]
Ultramarine used in the present invention has a volume average particle size of 0.3 to 3.0 μm, preferably 0.3 to 2.0 μm, and more preferably 0.5 to 1.5 μm. If the volume average particle diameter is smaller than 0.3 μm, sulfur in ultramarine is liberated, which is not preferable. Conversely, if it is larger than 3.0 μm, the toner will appear reddish, making it unsuitable as a black toner.
[0035]
In the present invention, ultramarine preferably has a pH of 7.5 or more, more preferably 8.5 or more, and still more preferably 7.5 to 10.5. Ultramarine is weakly decomposed to acid, and therefore, it is not preferable that the pH is 7.5 or less. Conversely, if the pH is too high, the compatibility with the carbon black and the resin is reduced, and the carbon black is easily released, so that the pH is preferably 10.5 or less.
[0036]
In the present invention, ultramarine preferably has an oil absorption of 15 to 40 ml / 100 g, more preferably 20 to 40 ml / 100 g, and still more preferably 28 to 40 ml / 100 g. If the oil absorption is less than 15 ml / 100 g, the dispersibility of ultramarine in the toner particles will be insufficient, and the dispersibility of carbon black and the release agent will also decrease. Conversely, if the oil absorption exceeds 40 ml / 100 g, the resistance of the toner tends to decrease. Particularly, the charge amount in a high-temperature and high-humidity environment decreases, and problems such as toner scattering and fog tend to occur.
[0037]
Next, the carbon black used in the present invention will be described.
[0038]
The carbon black used in the present invention is a carbon black obtained by a method of producing furnace black, gas black thermal black, acetylene black, lamp black, etc., and the method of producing the carbon black is not particularly limited.
[0039]
In the present invention, the carbon black preferably has an average primary particle size of 14 to 60 nm, more preferably 17 to 55 nm, and desirably 20 to 50 nm. If the average primary particle size is smaller than 14 nm, even if the above-mentioned ultramarine is used, it is difficult to uniformly disperse the toner. As a result, the absolute value of the charge amount of the toner is relatively low, and toner scattering or fogging is likely to occur. In addition, when the average primary particle size is smaller than 14 nm, the toner has a reddish tint and is unsuitable as black for full-color image formation. On the other hand, if the average primary particle size of the carbon black is larger than 60 nm, the coloring power is undesirably too low even if dispersed well. If such a large amount of carbon black having a large primary particle size is added to the toner in a large amount for the purpose of increasing the coloring power, the uniformity of charging is reduced, and fogging is likely to occur in durability under a low temperature and low humidity environment.
[0040]
In the toner of the present invention, the average primary particle size of the carbon black measured by cross-sectional TEM (transmission electron microscope) observation of the toner is desirably 14 to 60 nm. More specifically, from the cross-sectional photograph of the toner magnified 40,000 times, carbon black without aggregation was randomly extracted and analyzed, and the measurement was repeated until the number of samples exceeded 300 times To determine the average particle size. Here, spherical approximation was performed using an image processing apparatus, and a value defined from the obtained diameter was defined as the average primary particle size of carbon black. When directly measuring the average primary particle size of the carbon black from the TEM photograph, the longest diameter of the carbon black was used as the particle size, and the measurement was repeated until the number of samples exceeded 300 to obtain the average particle size.
[0041]
The pH of the carbon black used in the present invention is preferably 6.5 or more, more preferably 7.0 or more, and even more preferably 7.5 to 10.5. When the pH is lower than 6.5, the number of functional groups such as carboxyl groups and ketones increases, so that the association of the polyester becomes strong and the fixing property is easily inhibited. Conversely, if the pH is too high, the compatibility between the carbon black and the resin will be reduced, and the carbon black will be easily detached from the toner.
[0042]
In the present invention, the carbon black preferably has a volatile content of 1.5% or less, more preferably 1.2% or less. Carbon black having a volatile content of more than 1.5% means that there are many functional groups on the surface of the carbon black. Use of this type of carbon black tends to cause a decrease in the charge amount under high humidity. Solid uniformity is likely to deteriorate.
[0043]
The carbon black of the present invention preferably has a DBP oil absorption of 20 to 150 ml / 100 g, more preferably 30 to 140 ml / 100 g. If the oil absorption exceeds 150 ml / 100 g, the resistance of the toner tends to decrease, and the charge tends to decrease in the durability evaluation under a high temperature and high humidity environment, and problems such as toner scattering and fog tend to occur. Further, the uniform transferability under a low-temperature and low-humidity environment is reduced, and the image tends to be uneven. On the other hand, when the oil absorption is less than 20 ml / 100 g, the dispersibility of the carbon black in the toner particles is not sufficient, and the coloring power tends to decrease.
[0044]
Further, the carbon black used in the present invention has a specific surface area by nitrogen adsorption of 30 to 200 m.²/ G, more preferably 40 to 150 m²/ G, desirably 45 to 120 m²/ G. Specific surface area is 200m²If the ratio is larger than / g, uniform dispersion is difficult, and as a result, the absolute value of the charge amount of the toner becomes lower, which tends to cause toner scattering and fogging. In addition, the toner has a red tint, which makes it unsuitable as black for full-color image formation. Conversely, the specific surface area is 30m²If the ratio is smaller than / g, the coloring power becomes too low even if dispersed well, which is not preferable.
[0045]
Further, the carbon black used in the present invention has a toluene extraction of 0.1% or less, preferably 0.05% or less.
[0046]
In the toner of the present invention, carbon black is contained in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the binder resin. Preferably it is 1.0 to 8.0 parts by mass, more preferably 1.5 to 7.0 parts by mass. When the content of carbon black is less than 0.5 parts by mass per 100 parts by mass of the binder resin, the coloring power of the toner becomes too low, and it is difficult to obtain an image having a high image density. On the other hand, if the carbon black is used in an amount exceeding 10 parts by mass, it becomes difficult to control the charge of the toner, and the charge cannot be stabilized for a long time.
[0047]
The black toner of the present invention has a storage elastic modulus (G ′) at a temperature of 80 ° C. in order to improve the storage stability, heat resistance, and blocking resistance of the toner in a high temperature environment.₈₀) Is preferably 1 × 10⁶~ 1 × 10⁸[DN / m²And more preferably 1 × 10⁶~ 5 × 10⁷[DN / m²]. Storage modulus (G '₈₀) Is 1 × 10⁶[DN / m²], The storage stability, heat resistance, and blocking resistance in a high-temperature environment are poor, and the toner particles coalesce to form a large toner aggregate, which is not preferable. In recent years, as the output speed of copiers and printers has been increasing and the size of the main body has been reduced, the temperature inside the machine tends to increase, and in order to stably obtain high-definition and high-quality images, It is important that the toner has sufficient storage stability, heat resistance and blocking resistance in a high temperature environment. Further, the storage modulus (G ′)₈₀) Is 1 × 10⁸[DN / m²If it is larger than this, it is not preferable because sufficient storage stability, heat resistance and blocking resistance are obtained, but sufficient fixability at low temperatures cannot be obtained.
[0048]
Further, the loss tangent (tan δ) represented by the ratio (G ″ / G ′) of the storage elastic modulus (G ′) and the loss elastic modulus (G ″) at a temperature of 140 ° C._G) Is preferably from 0.2 to 1.5, more preferably from 0.3 to 1.10, in order to achieve a sufficient fixing property and high-temperature offset resistance, and further to obtain an image having uniform gloss. 0. Loss tangent (tan δ_GIs larger than 1.5, it is not preferable because sufficient high-temperature offset resistance of the toner cannot be obtained. In addition, loss tangent (tan δ_GWhen the value of ()) is smaller than 0.2, the toner cannot be sufficiently fixed, and the color developability of the toner is significantly reduced.
[0049]
As an index indicating the degree of dispersibility of carbon black, which is a feature of the black toner of the present invention, a loss tangent represented by a ratio (ε ″ / ε ′) between a dielectric loss factor (ε ″) and a dielectric constant (ε ′). (Tan δ_ε). The smaller this value is, the better the dispersibility of the carbon black is.
[0050]
In the present invention, the frequency 5 × 10⁴Tan δ in Hz_ε(5 × 10⁴Hz) is 0.008 or less and 1 × 10⁵Tan δ in Hz_ε(1 × 10⁵Hz) is 0.011 or less, and preferably tan δ_ε(5 × 10⁴Hz) is less than 0.006 and tan δ_ε(1 × 10⁵Hz) is 0.008 or less.
[0051]
tan δ_ε(5 × 10⁴Hz) is greater than 0.008 and tan δ_ε(1 × 10⁵(Hz) is greater than 0.011, the dispersibility of carbon black is inferior and non-uniform, so that the charge amount distribution of the toner is broad, and the image density is low due to charge-up under low humidity, and fogging or high humidity occurs. Insufficient amount of electrification causes adverse effects such as fogging, scattering, and poor transferability.
[0052]
As the binder resin used in the toner of the present invention,
(A) polyester resin,
(B) a hybrid resin having a polyester unit and a vinyl polymer unit,
(C) a mixture of the hybrid resin of the above (b) and a vinyl polymer,
(D) a mixture of a polyester resin and a vinyl polymer,
(E) A resin selected from any of the above-mentioned mixture of the hybrid resin and the polyester resin (b) is preferable.
[0053]
In addition, it is preferable that the molecular weight distribution of the binder resin measured by gel permeation chromatography (GPC) has a main peak (Mp) in a molecular weight region of 3,500 to 10,000. Preferably, the main peak has a molecular weight of 4,000 to 9,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 5.0 or more. When the main peak is in a region having a molecular weight of less than 3,500, the high-temperature offset resistance of the toner is insufficient. On the other hand, when the main peak is in a region having a molecular weight of more than 10,000, sufficient low-temperature fixability of the toner cannot be obtained, and OHP transparency becomes insufficient. Further, when Mw / Mn is less than 5.0, it becomes impossible to obtain good offset resistance.
[0054]
When a hybrid resin having the polyester unit and the vinyl polymer unit (b) is used as the binder resin, further improved wax dispersibility, low-temperature fixability, and offset resistance can be expected. The “hybrid resin” used in the present invention means a resin in which a vinyl polymer unit and a polyester unit are chemically bonded. Specifically, a polyester unit and a vinyl-based polymer unit obtained by polymerizing a monomer having a carboxylic acid ester group such as (meth) acrylic acid ester are formed by a transesterification reaction, preferably a vinyl-based polymer. Is a trunk polymer, and a graft copolymer (or a block copolymer) is formed using a polyester unit as a branch polymer.
[0055]
When a polyester resin and / or a hybrid resin is used as the binder resin, alcohol and carboxylic acid, or a carboxylic anhydride, a carboxylic acid ester, or the like can be used as a raw material monomer as a polyester monomer constituting these resins. Specifically, for example, as the dihydric alcohol component, 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 Alkylene oxide adducts of bisphenol A such as -bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, Opentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A And hydrogenated bisphenol A.
[0056]
Examples of the trihydric or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like No.
[0057]
As the acid component, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; And unsaturated anhydrides such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof.
[0058]
Among them, particularly, a bisphenol derivative represented by the following general formula (1) is used as a diol component, and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof, or a lower alkyl ester thereof (for example, fumaric acid) Acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) as an acid component, and a polyester resin obtained by polycondensation of these, as a black toner for full-color image formation, has excellent charging characteristics. Is preferred.
[0059]
Embedded image

(In the above formula, R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)
[0060]
When a vinyl polymer and / or a hybrid resin is used as the binder resin of the present invention, examples of the vinyl monomer constituting these resins include the following. Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert- Butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3, Styrene and its derivatives such as 4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene and p-nitrostyrene; styrene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated such as butadiene and isoprene Polyenes: vinyl chloride, vinylidene chloride, vinyl bromide, fluorine Vinyl halides such as vinyl; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and n-methacrylate. Α-methylene aliphatic monocarboxylic esters such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate , Propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-acrylic acid Acrylic acid esters such as lorethyl and phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole; N-vinyl compounds such as N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.
[0061]
Further, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid and mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride and alkenyl succinic anhydride Unsaturated dibasic acid anhydrides: methyl maleate half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Half esters of unsaturated dibasic acids such as methyl alkenyl succinate half ester, methyl half fumarate ester and methyl half ester mesaconate; unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid; acrylic acid, meta Α, β-unsaturated acids such as lylic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic anhydride and cinnamic anhydride; the α, β-unsaturated acids and lower fatty acids And monomers having a carboxyl group such as alkenyl malonic acid, alkenyl glutaric acid, alkenyl adipic acid, acid anhydrides and monoesters thereof.
[0062]
Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) And a monomer having a hydroxy group such as (-methylhexyl) styrene.
[0063]
In the toner of the present invention, the vinyl polymer unit used as the binder resin and / or the vinyl polymer unit of the hybrid resin may have a cross-linked structure cross-linked with a cross-linking agent having two or more vinyl groups. Good. Examples of the crosslinking agent used in this case include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; and diacrylate compounds linked by an alkyl chain such as ethylene glycol diacrylate and 1,3-butylene glycol divinyl compound. Acrylates, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate and those obtained by replacing acrylates of the above compounds with methacrylates; ethers Examples of diacrylate compounds linked by an alkyl chain containing a bond include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, and polyethylene. Glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and methacrylates instead of the above compounds; dimers linked by a chain containing an aromatic group and an ether bond. As the acrylate compounds, for example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate and The compounds in which acrylate of the above compounds is replaced with methacrylate may be mentioned.
[0064]
Examples of the polyfunctional crosslinking agent include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and acrylates of the above compounds replaced with methacrylate; triallylcia Nurate and triallyl trimellitate are exemplified.
[0065]
In the present invention, the vinyl polymer component and / or the polyester resin component preferably contain a monomer component capable of reacting with both resin components. Among the monomers constituting the polyester resin component, those which can react with the vinyl polymer include, for example, unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid and itaconic acid or anhydrides thereof. Among the monomers constituting the vinyl polymer component, those which can react with the polyester resin component include those having a carboxyl group or a hydroxy group, and acrylic acid or methacrylic acid esters.
[0066]
As a method for obtaining a reaction product of a vinyl polymer and a polyester resin, where a polymer containing a monomer component capable of reacting with each of the above-mentioned vinyl polymer and polyester resin is present, either one or A method obtained by polymerizing both resins is preferred.
[0067]
Examples of the polymerization initiator used for producing the vinyl polymer and the vinyl polymer unit according to the present invention include, for example, 2,2′-azobisisobutyronitrile and 2,2′-azobis (4- Methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), dimethyl-2,2′-azo Bisisobutyrate, 1,1'-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2'-azobis (2,4,4-trimethylpentane), 2-phenylazo -2,4-dimethyl-4-methoxyvaleronitrile, 2,2'-azobis (2-methyl-propane), methyl ethyl ketone peroxide, acetyl Ketone peroxides such as seton peroxide and cyclohexanone peroxide, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethyl Butyl hydroperoxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, di-cumyl peroxide, α, α′-bis (tert-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide , Decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioyl peroxide, di-isopropylperoxydi -Carbonate, di-2-ethylhexylperoxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethylperoxycarbonate, di-methoxyisopropylperoxydicarbonate, di (3-methyl-3-methoxy) Butyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, tert-butylperoxyacetate, tert-butylperoxyisobutyrate, tert-butylperoxyneodecanoate, tert-butylperoxy-2-ethylhexanoate, tert-butyl peroxy laurate, tert-butyl peroxy benzoate, tert-butyl peroxy isopropyl carbonate, di-tert-butyl peroxy isophthalate, ter - butylperoxy allyl carbonate, tert- amyl peroxy 2-ethyl hexanoate, di -tert- butyl peroxy hexahydro terephthalate, include di -tert- butyl peroxy azelate.
[0068]
Examples of the method for producing the hybrid resin used in the present invention include the following production methods (1) to (6).
[0069]
(1) A method in which a vinyl polymer, a polyester resin, and a hybrid resin component are blended after each production, and the blend is produced by dissolving and swelling in an organic solvent (for example, xylene) and then distilling off the organic solvent. The hybrid resin component is synthesized by separately producing a vinyl polymer and a polyester resin, dissolving and swelling in a small amount of an organic solvent, adding an esterification catalyst and an alcohol, and performing a transesterification reaction by heating. Can be used.
[0070]
(2) This is a method of producing a polyester unit and a hybrid resin component in the presence of a vinyl polymer unit after the production. The hybrid resin component is produced by reacting a vinyl-based polymer unit (a vinyl-based monomer can be added if necessary) with a polyester monomer (alcohol, carboxylic acid) and / or polyester. Also in this case, an organic solvent can be appropriately used.
[0071]
(3) This is a method for producing a vinyl-based polymer unit and a hybrid resin component in the presence of a polyester unit after the production. The hybrid resin component is produced by a reaction between a polyester unit (a polyester monomer can be added if necessary) and a vinyl monomer and / or vinyl polymer unit.
[0072]
(4) After the production of the vinyl polymer unit and the polyester unit, a hybrid resin component is produced by adding a vinyl monomer and / or a polyester monomer (alcohol, carboxylic acid) in the presence of these polymer units. Also in this case, an organic solvent can be appropriately used.
[0073]
(5) After producing the hybrid resin component, vinyl polymer and / or polyester monomer (alcohol, carboxylic acid) is added to carry out addition polymerization and / or polycondensation reaction to produce vinyl polymer unit and polyester unit. Is done. In this case, as the hybrid resin component, those produced by the above-mentioned production methods (2) to (4) can be used, and if necessary, those produced by a known production method can be used. Further, an organic solvent can be appropriately used.
[0074]
(6) A vinyl-based polymer unit, a polyester unit and a hybrid resin component are produced by mixing a vinyl-based monomer and a polyester monomer (alcohol, carboxylic acid, etc.) and continuously performing addition polymerization and polycondensation reaction. Further, an organic solvent can be appropriately used.
[0075]
In the production methods (1) to (5), the vinyl-based polymer unit and / or the polyester unit may be a plurality of polymer units having different molecular weights and degrees of crosslinking.
[0076]
The glass transition temperature of the binder resin used in the toner of the present invention is preferably from 40 to 90 ° C, more preferably from 45 to 85 ° C. Further, the acid value of the binder resin is preferably 1 to 40 mgKOH / g.
[0077]
Next, the release agent used in the present invention will be described.
[0078]
As the release agent used in the present invention, one or more waxes are desirable.
[0079]
In the endothermic curve in the differential thermal analysis (DSC) measurement, the toner of the present invention containing the wax may have one or more toners in a temperature range of 30 to 200 ° C from the viewpoint of achieving both low-temperature fixability and blocking resistance. It is desirable to have an endothermic peak and the peak temperature of the maximum endothermic peak in the endothermic peak is in the range of 60 to 110 ° C. More preferably, it is desirable that there is a maximum peak of the endothermic curve in the range of 65 to 100 ° C. When the peak temperature of the maximum endothermic peak is lower than 60 ° C., the blocking resistance of the toner is deteriorated.
[0080]
As the wax used in the present invention, for example, low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, aliphatic hydrocarbon-based wax such as paraffin wax, or an oxide of an aliphatic hydrocarbon-based wax such as oxidized polyethylene wax, or Block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax, sasol wax and montanic acid ester wax, and those obtained by partially or entirely deoxidizing fatty acid esters such as deoxidized carnauba wax. And the like. Further, saturated straight-chain fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brandinic acid, eleostearic acid, and vinaric acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, and seryl alcohol And polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide and lauric acid amide; methylenebisstearic acid amide, ethylenebiscapric acid amide and ethylenebislaurin Saturated fatty acid bisamides such as acid amide and hexamethylene bisstearic acid amide; ethylene bisoleic acid amide, hexamethylene bis oleic acid amide, N, N'-dioleyl adipamide, N, N ' Unsaturated fatty acid amides such as dioleylsebacic acid amide; aromatic bisamides such as m-xylene bisstearic acid amide and N, N'-distearylisophthalic acid amide; calcium stearate, calcium laurate, zinc stearate and stearin Aliphatic metal salts such as magnesium silicate (commonly referred to as metallic soaps); waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid; behenic acid monoglycerides Partial esterified products of fatty acids and polyhydric alcohols; and methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.
[0081]
In addition, the wax preferably used in the present invention includes an aliphatic hydrocarbon-based wax. For example, low molecular weight alkylene polymer obtained by radical polymerization of alkylene under high pressure or Ziegler catalyst under low pressure; alkylene polymer obtained by thermally decomposing high molecular weight alkylene polymer; Preferred is a synthetic hydrocarbon wax obtained from the distillation residue of hydrocarbons obtained by the method or by hydrogenating them. Further, those obtained by separating a hydrocarbon wax by use of a press sweating method, a solvent method, vacuum distillation or a fractional crystallization method are more preferably used. The hydrocarbon as a base is synthesized by synthesizing carbon monoxide and hydrogen using a metal oxide catalyst (often a multi-component system of two or more types) [for example, the Zintol method, the hydrochol method (fluidized catalyst bed). Hydrocarbon compounds synthesized by the use); hydrocarbons having a carbon number of up to about several hundreds obtained by the Aggé method (using an identified catalyst bed) in which a large amount of waxy hydrocarbons can be obtained; alkylene such as ethylene by a Ziegler catalyst The polymerized hydrocarbon is preferred because it is a straight-chain hydrocarbon having a small number of branches, a small number of branches, and a long saturation. Particularly, a wax synthesized by a method not based on the polymerization of alkylene is preferable in view of its molecular weight distribution.
[0082]
In the molecular weight distribution of the wax, the main peak is preferably in a region having a molecular weight of 400 to 2400, and more preferably in a region having a molecular weight of 430 to 2000. By providing such a molecular weight distribution, favorable thermal characteristics can be imparted to the toner.
[0083]
In the present invention, the wax used as the release agent is preferably used in an amount of 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, per 100 parts by mass of the binder resin.
[0084]
The wax is usually contained in the binder resin by a method in which the resin is dissolved in a solvent, the temperature of the resin solution is raised, and the mixture is added and mixed while stirring, or a method in which the wax is mixed during kneading.
[0085]
The toner of the present invention may contain a metal compound of an aromatic carboxylic acid derivative for stabilizing charge. This not only functions as a charge control agent, but also contributes to improving the dispersibility of carbon black.
[0086]
The reason why the metal compound of the aromatic carboxylic acid derivative improves the dispersibility of the carbon black is unknown, but due to the interaction between the binder resin and the metal compound of the aromatic carboxylic acid derivative, a partial crosslinking reaction proceeds, and the kneading is performed. It is considered that the dispersibility of the hardly dispersible carbon black was increased by increasing the share of the carbon black at that time. In addition, the metal compound of the aromatic carboxylic acid derivative surrounds the carbon black and functions like a dispersion stabilizing agent of the carbon black. It is thought that it is functioning as well.
[0087]
Examples of the aromatic carboxylic acid include three kinds of compounds represented by the following formulas (2) to (4).
[0088]
Embedded image

[In the above formula, R₁~ R₇Each represents hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, -OH, -NH₂, -NH (CH₃), -N (CH₃)₂, -OCH₃, -O (C₂H₅), -COOH, -CONH₂Is shown. ]
[0089]
In the above compound, preferred R₁Examples include a hydroxyl group, an amino group and a methoxy group, and among them, a hydroxyl group is preferable. As the aromatic carboxylic acid, an aluminum compound of di-tert-butylsalicylic acid is particularly preferable.
[0090]
As the metal compound of the aromatic carboxylic acid, for example, an aromatic carboxylic acid is dissolved in an aqueous sodium hydroxide solution, an aqueous solution in which divalent or higher valent metal atoms are melted is added dropwise to the aqueous sodium hydroxide solution, and the mixture is heated and stirred. After adjusting the pH of the aqueous solution, cooling to room temperature, and washing with filtered water, a metal compound of an aromatic carboxylic acid can be synthesized. However, it is not limited only to the above synthesis method.
[0091]
The amount of the metal compound of the aromatic carboxylic acid to be used is preferably 0.5 to 10 parts by mass, more preferably 1.10 parts by mass, per 100 parts by mass of the binder resin in order to adjust the viscoelasticity and triboelectricity of the toner. 5 to 8 parts by mass. When the amount of the metal compound is less than 0.5 part by mass, not only does it not function very much as a charge control agent, but good carbon black dispersibility cannot be achieved. On the other hand, when the amount is more than 10 parts by mass, the crosslinking is excessively advanced, and the fixability as a toner is impaired.
[0092]
In the present invention, a compound other than the above-mentioned metal compound of aromatic carboxylic acid may be used as a charge control agent.
[0093]
As a method for producing the black toner of the present invention, for example, a binder resin, carbon black, ultramarine, a release agent, and if necessary, a charge control agent and other additives are sufficiently mixed in a mixer such as a Henschel mixer. After mixing, using a hot kneader such as a heating roll, kneader, extruder, melting, kneading, and kneading to disperse the carbon black in the resin and to disperse the carbon black, solidify by cooling, and then pulverize. And strict classification to obtain black toner particles.
[0094]
In the present invention, in order to improve the dispersion state of the carbon black in the toner particles, the first binder resin, ultramarine, and carbon black are charged into a kneader or a mixer and mixed under non-pressurization or under pressure. To melt the first binder resin, and then obtain a first kneaded material sufficiently kneaded with a kneader such as a three-roll machine, and then add the second binder resin to the first kneaded material. Further, if necessary, a mixture obtained by adding an additive such as a charge control agent, a release agent, and the like, is heated and melt-kneaded to obtain a second kneaded product. It is preferred to classify the toner. Here, the first binder resin and the second binder resin may be the same or different resins.
[0095]
Examples of the kneading apparatus include a heating kneader, a single-screw extruder, and a twin-screw extruder, and particularly preferably a heating kneader.
[0096]
The weight average particle diameter of the black toner of the present invention is preferably 4 to 10 μm, and the number average particle diameter is preferably 3.5 to 9.5 μm. Further, it is preferable that 5 to 50% by number of particles having a particle diameter of 4 μm or less in the number distribution of the toner and 5% by volume or less of particles having a particle diameter of 12.70 μm or more in the volume distribution.
[0097]
When the weight average particle diameter of the toner is larger than 10 μm, it means that there are few fine particles which can contribute to high image quality, and there is an advantage that a high image density is easily obtained and the fluidity of the toner is excellent. It is difficult to adhere faithfully on the above fine electrostatic image, and the reproducibility of the highlight portion is reduced, and the resolution is also reduced. Further, the toner tends to ride on the electrostatic image more than necessary, which tends to increase the toner consumption.
[0098]
Further, when the weight average particle diameter of the toner is smaller than 4 μm, the charge amount per unit weight of the toner is increased, and the image density is reduced, particularly, the image density under low temperature and low humidity is remarkable. Therefore, it is not suitable especially for a use having a high image area ratio such as a graphic image.
[0099]
Further, when the weight average particle diameter of the toner is smaller than 4 μm, it is difficult to smoothly charge the toner with a charging member such as a carrier, and the amount of toner that cannot be sufficiently charged increases. Becomes noticeable. To cope with this, it is conceivable to reduce the diameter of the carrier in order to increase the specific surface area of the carrier. However, in the case of a toner having a weight average particle size of less than 4 μm, self-aggregation of the toner is likely to occur, and uniform mixing with the carrier can be achieved in a short time. The toner tends to be fogged during continuous replenishment of toner.
[0100]
In the toner of the present invention, toner particles having a particle diameter of 4 μm or less are preferably 5 to 50% by number of the total number of particles, and more preferably 5 to 25% by number. When the number of toner particles having a particle diameter of 4 μm or less is less than 5% by number, it means that there are few fine toner particles which are essential components for high image quality. As the toner is continuously used, the effective toner particle component decreases, the balance of the toner particle size distribution shown in the present invention deteriorates, and the image quality tends to gradually decrease.
[0101]
If the number of toner particles having a particle diameter of 4 μm or less exceeds 50% by number, aggregates of the toner particles are likely to be formed, and the toner particles often behave as a toner lump having an original particle diameter. An image is easily formed, the resolution is reduced, or the density difference between the edge portion and the inside of the electrostatic charge image is increased, so that the image tends to be slightly hollow. Further, it is preferable that particles having a particle diameter of 12.70 μm or more be 5% by volume or less from the viewpoint of improving image quality.
[0102]
Further, it is preferable that a fluidity improver is externally added to the toner of the present invention from the viewpoint of improving image quality and preserving even under a high temperature environment. As the fluidity improver, inorganic fine powders such as silica, titanium oxide and aluminum oxide are preferable. The inorganic fine powder is preferably hydrophobized with a hydrophobizing agent such as a silane coupling agent, silicone oil or a mixture thereof.
[0103]
Examples of the hydrophobizing agent include coupling agents such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a zircoaluminate coupling agent.
[0104]
Specifically, for example, as a silane coupling agent, a general formula
R_m-Si-Y_n
[Wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents an alkyl group, a vinyl group, a phenyl group, a methacryl group, an amino group, an epoxy group, a mercapto group or a derivative thereof. , N represents an integer of 1 to 3. ]
Is preferably represented by For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxy Examples thereof include propyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.
[0105]
The treatment amount is preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass, based on 100 parts by mass of the inorganic fine powder.
[0106]
The hydrophobizing agent preferably used in the present invention has the following general formula
C_nH_{2n + 1}-Si- (OC_mH_{2m + 1})₃
[In the above formula, n shows the integer of 4-12, m shows the integer of 1-3. ]
And an alkylalkoxysilane coupling agent represented by the formula: When n is less than 4 in the alkylalkoxysilane coupling agent, the treatment becomes easy, but the hydrophobicity is low, which is not preferable. When n is larger than 12, the hydrophobicity is sufficient, but the coalescence of the titanium oxide fine particles increases, and the fluidity-imparting ability tends to decrease. If m is greater than 3, the reactivity of the alkylalkoxysilane coupling agent will be reduced, making it difficult to achieve good hydrophobicity. More preferred alkylalkoxysilane coupling agents have n of 4 to 8 and m of 1 to 2.
[0107]
The processing amount of the alkylalkoxysilane coupling agent is preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass, based on 100 parts by mass of the inorganic fine powder.
[0108]
The hydrophobizing treatment may be performed with one type of hydrophobizing agent alone, or two or more types of hydrophobizing agents may be used simultaneously or sequentially.
[0109]
The fluidity improver is preferably added in an amount of 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, per 100 parts by mass of the toner particles.
[0110]
The black toner of the present invention is applicable to both one-component developers and two-component developers. Examples of the carrier used when the toner of the present invention is used in a two-component developer include, for example, surface-oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, and rare earths, and alloys thereof. Alternatively, oxides and ferrites can be used.
[0111]
Particularly, magnetic ferrite particles of three elements of Mn-Mg-Fe formed mainly of manganese, magnesium and iron are preferable as carrier particles. The magnetic carrier particles are preferably coated with a resin, and the coating resin is preferably a silicone resin. In particular, a nitrogen-containing silicone resin, or a modified silicone resin produced by the reaction of a nitrogen-containing silane coupling agent with a silicone resin has a property of imparting a negative triboelectric charge to the toner of the present invention, environmental stability, and carrier. This is preferable in terms of suppressing contamination of the surface.
[0112]
The magnetic carrier preferably has an average particle size of 15 to 60 μm, more preferably 25 to 50 μm, in view of the weight average particle size of the toner of the present invention. As a method of adjusting the magnetic carrier so as to have the average particle diameter, for example, classification by using a sieve can be mentioned. In particular, in order to perform classification with high accuracy, it is preferable to sieve a plurality of times using a sieve having an appropriate opening. It is also effective to use a mesh whose opening shape is controlled by plating or the like.
[0113]
When adjusting the two-component developer using the toner of the present invention, the mixing ratio of the toner and the carrier is preferably 2 to 15% by mass, more preferably 4 to 13% by mass, as the toner concentration in the developer. Then, usually good results are obtained. If the toner density is less than 2% by mass, the image density tends to be low, and if it is more than 15% by mass, fog and scattering in the machine are likely to increase.
[0114]
FIG. 1 shows an example of an image forming apparatus for forming a full-color image using the black toner of the present invention, and an image forming method in the apparatus will be described.
[0115]
The image forming apparatus shown in FIG. 1 includes a lower digital color image printer unit I and an upper digital color image reader unit II. For example, based on an image of a document D read by the reader unit II, the printer unit In I, an image is formed on the recording material P.
[0116]
First, the printer unit I will be described.
[0117]
The printer unit I has a photosensitive drum 1 as an electrostatic image carrier that is driven to rotate in the direction of arrow R1. Around the photoreceptor drum 1, a primary charger (charging unit) 2, an exposing unit 3, a developing unit (developing unit) 4, a transfer unit 5, a cleaning unit 6, and a pre-exposure lamp 7 are sequentially arranged along the rotation direction. Etc. are arranged. Below the transfer device 5 (that is, in the lower half of the printer unit I), a paper feeding and conveying unit 8 for the recording material P is arranged, and above the transfer device 5, a separating unit 9 is provided. Downstream (downstream in the transport direction of the recording material P), a heating / pressing fixing device 10 and a paper discharge unit 11 are arranged.
[0118]
The photoreceptor drum 1 has a substrate 1a on an aluminum drum and an OPC (organic semiconductor) photoreceptor 1b covering the surface thereof, and is driven at a predetermined process speed (in the direction of arrow R1) by driving means (not shown). (Peripheral speed).
[0119]
The primary charger 2 includes a shield 2a having an opening at a portion facing the photoconductor drum 1, a discharge wire 2b arranged inside the shield 2a in parallel with a generatrix of the photoconductor drum 1, and an opening at the opening of the shield 2a. And a grid 2c for regulating the charging potential. A charging bias is applied to the primary charger 2 by a power supply (not shown), whereby the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and a predetermined potential.
[0120]
The exposure unit 3 includes a laser output unit (not shown) that emits a laser beam based on an image signal from a reader unit II described later, a polygon mirror 3a that reflects the laser beam, a lens 3b, and a mirror 3c. . The exposure unit 3 is configured to irradiate the surface of the photosensitive drum 1 with the laser light to expose the photosensitive drum 1 and remove an electric charge of an exposed portion to form an electrostatic latent image. In the apparatus shown in FIG. 1, the electrostatic latent image formed on the surface of the photosensitive drum 1 is separated into four colors of yellow, cyan, magenta, and black based on the image of the original, and the images correspond to the respective colors. The electrostatic latent images are sequentially formed.
[0121]
The developing device 4 includes developing devices 4Y and 4C that store yellow toner, cyan toner, magenta toner, and black toner (developer) in order from the upstream side along the rotation direction of the photosensitive drum 1 (the direction of arrow R1). , 4M, 4Bk. Each of the developing units 4Y, 4C, 4M, and 4Bk has a developing sleeve 4a that carries a developer having a toner for developing the electrostatic image formed on the surface of the photosensitive drum 1, and the electrostatic image is formed. The developing device of a predetermined color to be used for the development is alternatively disposed at a developing position close to the surface of the photosensitive drum 1 by the eccentric cam 4b. The toner of the developer carried on the developing sleeve 4a develops the electrostatic charge image to form a visible toner image as a visible image. The three color developing units other than the developing unit used for the development are retracted from the developing position.
[0122]
The transfer device 5 includes a transfer drum (recording material carrier) 5a that carries a recording material P on the surface, a transfer charger (transfer charging unit) 5b that transfers the toner image on the photosensitive drum 1 to the recording material P, and a recording material. It has an adsorption charger 5c for adsorbing P to the transfer drum 5a, an adsorption roller 5d opposed thereto, an inner charger 5e, and an outer charger 5f, and is rotatably supported in the direction of arrow R5. A recording material carrying sheet 5g made of a dielectric is integrally stretched in a cylindrical shape in a peripheral opening area of the transfer drum 5a. The recording material supporting sheet 5g uses a dielectric sheet such as a polycarbonate film. The transfer device 5 is configured to adsorb and carry the recording material P on the surface of the transfer drum 5a.
[0123]
The cleaning device 6 includes a cleaning blade 6a for scraping off residual toner remaining on the surface of the photosensitive drum 1 without being transferred to the recording material P, and a cleaning container 6b for collecting the scraped toner.
[0124]
The pre-exposure lamp 7 is disposed adjacent to the upstream side of the primary charger 2 and removes unnecessary charges on the surface of the photosensitive drum 1 cleaned by the cleaning unit 6.
[0125]
The sheet feeding and conveying unit 8 includes a plurality of sheet feeding cassettes 8a for stacking and storing recording materials P having different sizes, a sheet feeding roller 8b for feeding the recording materials P in the sheet feeding cassette 8a, a number of conveying rollers, It has a roller 8c and the like, and supplies a recording material P of a predetermined size to the transfer drum 5a.
[0126]
The separation unit 9 includes a separation charger 9a for separating the recording material P after the transfer of the toner image from the transfer drum 5a, a separation claw 9b, a separation pushing roller 9c, and the like.
[0127]
The heat-pressure fixing device 10 includes a fixing roller 10a having a heater inside, and a pressure roller 10b disposed below the fixing roller 10a and pressing the recording material P against the fixing roller 10a.
[0128]
The paper discharge unit 11 includes a transport path switching guide 11a, a discharge roller 11b, a paper discharge tray 11c, and the like, which are arranged on the downstream side of the heat and pressure fixing device 10. Below the conveyance path switching guide 11a, a conveyance vertical path 11d, a reversing path 11e, a stacking member 11f, an intermediate tray 11g, and a conveyance roller for forming an image on both sides of one recording material P. 11h, 11i, a reversing roller 11j and the like are arranged.
[0129]
A potential sensor S1 for detecting the charged potential on the surface of the photosensitive drum 1 is provided between the primary charger 2 and the developing device 4 around the photosensitive drum 1, and between the developing device 4 and the transfer drum 5a. Is provided with a density sensor S2 for detecting the density of the toner image on the photosensitive drum 1.
[0130]
Next, the reader unit II will be described.
[0131]
The reader unit II disposed above the printer unit I includes a document table glass 12a on which the document D is placed, an exposure lamp 12b that exposes and scans the image surface of the document D while moving, and further reflects light reflected from the document D. A plurality of mirrors 12c for condensing the reflected light, a full-color sensor 12e for forming a color-separated image signal based on the light from the lens 12d, and the like. The color-separated image signal is processed by a video processing unit (not shown) through an amplifier circuit (not shown), and is sent to the above-described printer unit I.
[0132]
Next, the operation of the image forming apparatus having the configuration shown in FIG. 1 will be described. In the following description, it is assumed that four full-color images are formed in the order of yellow, cyan, magenta, and black.
[0133]
The image of the document D placed on the platen glass 12a of the reader unit II is irradiated by an exposure lamp, color-separated, and a yellow image is first read by a full-color sensor 12e, subjected to a predetermined process, and converted into an image signal. It is sent to the printer unit I.
[0134]
In the printer unit I, the photosensitive drum 1 is driven to rotate in the direction of arrow R1, and the surface is uniformly charged by the primary charger 2. A laser beam is emitted from the laser output unit of the exposure unit 3 based on the image signal sent from the reader unit II described above, and the surface of the charged photosensitive drum 1 is charged by a light image E via a polygon mirror 3a and the like. Expose. The exposed portion of the surface of the photoreceptor drum 1 has its charge removed, whereby the yellow developing device 4Y is disposed at a predetermined developing position, and the other developing devices 4C, 4M, and 4Bk are retracted from the developing position. The yellow toner is attached to the electrostatic charge image on the photosensitive drum 1 by the developing device 4Y, and is visualized to be a yellow toner image. The yellow toner image on the photosensitive drum 1 is transferred onto the recording material P carried on the transfer drum 5a. The recording material P is wound around the transfer drum 5a at a predetermined timing from a predetermined paper feeding cassette 8a via a paper feeding roller 8b, a conveying roller, a registration roller 8c, and the like. , And rotates in the direction of arrow R5, and the yellow toner image on the photosensitive drum 1 is transferred by the transfer charger 5b.
[0135]
On the other hand, on the photosensitive drum 1 after the transfer of the yellow toner image, the residual toner on the surface is removed by the cleaning device 6, unnecessary charges are removed by the pre-exposure lamp 7, and the next image formation starting from primary charging Offered to
[0136]
The processes from the reading of the document image by the reader unit II, the transfer of the toner image to the recording material P on the transfer drum 5a, the cleaning of the photosensitive drum 1, and the charge removal are performed in other colors than yellow, that is, , Cyan, magenta, and black are similarly performed, and four color toner images of a yellow toner, a cyan toner, a magenta toner, and a black toner are transferred onto the recording material P on the transfer drum 5a so as to overlap.
[0137]
The recording material P to which the four color toner images have been transferred is separated from the transfer drum 5a by the separation charger 9a, the separation claw 9b, and the like, and is conveyed to the fixing device 10 in a state where the unfixed toner image is carried on the surface. You. The recording material P is heated and pressed by the fixing roller 10a and the pressure roller 10b of the heating and pressing fixing device 10, and the color toner image is melted and fixed, so that a full-color image is formed on one surface of the recording material P. . The recording material P after fixing is discharged onto a paper discharge tray 11c by a discharge roller 11b.
[0138]
Next, FIG. 2 shows an enlarged view of the heating and pressing fixing device 10 in FIG. 1 and the fixing device will be described.
[0139]
In FIG. 2, a fixing roller 10a that comes into contact with the toner image includes, for example, an HTV (high-temperature vulcanization type) silicone rubber layer 32 having a thickness of 1 mm on an aluminum core bar 31 and a specific additional silicone rubber layer 33 on the outside thereof. And has a diameter of 60 mm.
[0140]
On the other hand, the pressure roller 10b is provided with, for example, an HTV having a thickness of 1 mm and a specific additional silicone rubber layer 35 having a thickness of 1 mm on a core metal 34 made of aluminum, and has a diameter of 60 mm. .
[0141]
The above-described fixing roller 10a is provided with a transport roller heater 36, which is a heating means, in the cored bar 31, and the pressure roller 10b is also provided with a heater 37 in the cored bar 34. Heating from The temperature of the pressure roller 10b is detected by the thermistor 38 in contact with the pressure roller 10b, and based on the detected temperature, the control devices 39 control the Harongen heaters 36 and 37, and the fixing roller 10a and the pressure roller 10b Are controlled so that both of them are maintained at a predetermined temperature. Note that the fixing roller 10a and the pressure roller 10b are pressed at a predetermined pressure by a pressure mechanism (not shown).
[0142]
In FIG. 2, O is an oil application device, C is a cleaning device, and C1 is a cleaning blade for removing oil stains on the pressure roller 10b. The oil application device O controls the dimethyl silicone oil 41 in the oil pan 40 via the oil pumping rollers 50 and 42 and the oil application roller 43 to regulate the amount of oil applied by the oil application amount adjusting blade 44 and hits the fixing roller 10a. The surface of the fixing roller 10a is cleaned by the contacted web 46.
[0143]
In the fixing device 10 described above, the recording material P carrying the unfixed toner image on the surface is nipped and conveyed to a fixing nip between the fixing roller 10a and the pressure roller 10b. The toner is fixed. At this time, the toner adhered to the fixing roller 10a and the pressure roller 10b is removed by the cleaning device C and the cleaning blade C1, respectively.
[0144]
The method of forming a full-color image on only one surface of a recording material has been described above. Next, a method of forming a full-color image on both surfaces of a recording material will be described.
[0145]
When a full-color image is formed on both sides of the recording material P, the heating / pressing fixing device 10 immediately drives the conveyed recording material P on the conveyed path switching guide 11a, passes the conveyed path 11d to the reversing path 11e. After being guided once, the reversing roller 11j is rotated in reverse so that the rear end at the time of feeding is retreated, and the sheet is retracted in a direction opposite to the direction of feeding, and is stored in the intermediate tray 11g. Thereafter, the recording material P having a full-color image on one surface of the intermediate tray 11g is sent to the transfer drum 5a, and the yellow toner, cyan toner and magenta toner are again transferred to the other surface by the above-described image forming process. The black toner is further transferred. Since the full-color image of the recording material P comes into contact with the transfer drum 5a, the silicone oil attached to the full-color image surface at the time of fixing adheres to the transfer drum 5a and easily hinders the transfer process. Since the silicone oil has excellent absorbability, the amount of silicone oil adhering to the transfer drum 5a is extremely small as compared with the related art.
[0146]
The recording material P having an unfixed color toner image on the other surface is separated from the transfer drum 5a and sent to the heating and pressing fixing device 10, and the unfixed color toner image is transferred to the other surface of the recording material P. The recording material P is fixed by heating and pressing, and a full-color image is formed on both surfaces of the recording material P. At this time, since the black toner of the present invention contains carbon black in a good dispersion and contains an appropriate amount of release agent, images are formed well on both sides, and recording is performed on the fixing roller 10a and the pressure roller 10b. The winding of the material P is suppressed, and the occurrence of the offset phenomenon is well prevented.
[0147]
When the black toner of the present invention is used, the contamination of the recording material carrying sheet 5g of the transfer drum 5a with silicone oil and the like is extremely small as compared with the related art, but if necessary, the fur brush 13a, the backup brush 13b, and the oil removing roller 14a And the backup brush 14b for cleaning. Such cleaning is performed before or after image formation as necessary, and is performed as needed when a jam (paper jam) occurs.
[0148]
Next, a method for measuring each physical property will be described.
[0149]
(Method of measuring volume average particle size of ultramarine)
The measurement is performed using a laser diffraction / scattering type particle size distribution analyzer (“LA-920” manufactured by Horiba).
[0150]
[Method of measuring oil absorption]
The oil absorption of ultramarine is measured according to JIS K5101-21, and the oil absorption of carbon black is measured according to JIS K6221A.
[0151]
[Method of measuring pH]
The pH of ultramarine is measured according to JIS K5101-26, and the pH of carbon black is measured according to DIN ISO 787/9.
[0152]
(Method of measuring viscoelasticity of toner)
The toner is pressed into a disk-shaped sample having a diameter of 8 mm and a thickness of about 2 to 3 mm. Next, the temperature is set in a parallel plate, and the temperature is gradually increased within a temperature range of 50 to 200 ° C. to perform temperature dispersion measurement. The heating rate is 2 ° C./min, the angular frequency (ω) is fixed at 6.28 rad / sec, and the distortion rate is automatic. The horizontal axis represents temperature, and the vertical axis represents storage modulus (G ′) and loss modulus (G ″), and the value at each temperature is read. For measurement, RDA-II (manufactured by Rheometrics) is used. .
[0153]
[Method of measuring dielectric loss tangent of toner]
After calibration at a frequency of 1 kHz and 1 MHz using a 4284A Precision LCR meter (manufactured by Hewlett-Packard Company), a frequency of 5 × 10⁴Hz and 1 × 10⁵The dielectric loss tangent (tan δε) is calculated from the measured value of the dielectric constant in Hz.
[0154]
0.5 to 0.7 g of the toner is weighed and measured at 34300 kPa (350 kgf / cm²) Is applied for 2 minutes to form a disk having a diameter of 25 mm and a thickness of 1 mm or less (preferably 0.5 to 0.9 mm) to obtain a measurement sample. This measurement sample is mounted and fixed on an ARES (manufactured by Rheometric Scientific F.E.) equipped with a dielectric constant measuring jig (electrode) having a diameter of 25 mm. Thereafter, under a load of 3.43 N (350 g), 100 to 10⁶The measurement is performed three times in a frequency range of Hz, and an average value is calculated.
[0155]
[Method of measuring endothermic peak of toner]
It measures according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) and DSC-7 (made by Perkin Elmer).
[0156]
The measurement sample is precisely weighed in an amount of 5 to 20 mg, preferably 10 mg.
[0157]
This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rising rate of 10 ° C./min under normal temperature and normal humidity within a measurement temperature range of 30 to 200 ° C. In this heating process, an endothermic peak of the main peak of the DSC curve in the temperature range of 30 to 200 ° C. is obtained.
[0158]
[Method of measuring molecular weight distribution by GPC]
The molecular weight of a chromatogram by gel permeation chromatography (GPC) is measured under the following conditions. The column was stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) was passed through the column at this temperature as a solvent at a flow rate of 1 ml per minute, and the resin was adjusted to a sample concentration of 0.05 to 0.6% by mass. The measurement is performed by injecting about 50 to 200 μl of a THF sample solution. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number (retention time). As a standard polystyrene sample for preparing a calibration curve, for example, Tosoh Corporation or Pressure Chemical Co. Has a molecular weight of 6 × 10², 2.1 × 10³, 4 × 10³, 1.75 × 10⁴, 5.1 × 10⁴, 1.1 × 10⁵3.9 × 10⁵, 8.6 × 10⁵, 2 × 10⁶, 4.48 × 10⁶It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
[0159]
As a column, 10³~ 2 × 10⁶In order to accurately measure the molecular weight region of, a plurality of commercially available polystyrene gel columns may be combined, for example, a combination of Showex DPC's Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 and Waters, μ-styragel 500, 10³, 10⁴, 10⁵Can be cited.
[0160]
[Method of Measuring Particle Size Distribution of Toner]
In the present invention, the average particle size and the particle size distribution of the toner are measured using a Coulter Counter TA-II type (manufactured by Coulter Inc.), but a Coulter Multisizer (manufactured by Coulter Inc.) can also be used. As the electrolyte, a 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and the number of toner particles having a size of 2.00 μm or more are measured by using the measuring device with a 100 μm aperture. The distribution and number distribution were calculated. Then, the weight-based weight average particle diameter (D4) (the median value of each channel is a representative value for each channel) determined from the volume distribution according to the present invention was determined.
[0161]
As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 8.0 μm to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32.00 to 40.30 μm are used.
[0162]
(Method of measuring average primary particle size of carbon black)
In the present invention, the average primary particle size of carbon black in the toner was measured as follows.
[0163]
After sufficiently dispersing the toner in an ultraviolet-curable acrylic resin, the toner is cured by irradiating ultraviolet rays, and the obtained cured product is exposed using an ultramicrotome, which is then ruthenium tetroxide (RuO).₄) Or, if necessary, osmium tetroxide (OsO)₄) Was applied, and a thin sample was cut out using an ultramicrotome equipped with a diamond knife, and the cross-sectional layer morphology of the toner was observed using a transmission electron microscope (TEM). From the cross-sectional photograph of the toner obtained in this way (for example, a cross-sectional photograph magnified 40,000 times), carbon black having no aggregate formed was randomly extracted and analyzed, and the number of samplings was 300 times. The average particle diameter was determined by repeating the measurement until the average particle diameter exceeded the average particle diameter.
[0164]
In the present invention, carbon black is spherically approximated using an image processing apparatus, and a value defined by the obtained diameter is defined as an average primary particle size (A) of carbon black. When directly measuring the average primary particle size of carbon black from a TEM photograph, the major diameter of carbon black is used as the particle size, and the measurement is repeated until the number of samplings exceeds 300 to obtain the average primary particle size (B). I asked. In the present invention, substantially the same results were obtained in both (A) and (B).
[0165]
Hereinafter, embodiments of the present invention will be described.
[0166]
[Embodiment 1]
At least a binder resin, a release agent, 0.5 to 10 parts by mass of carbon black per 100 parts by mass of the binder resin, and a volume average particle size of 0.3 to 3.0 μm ultramarine. It is a characteristic black toner.
[0167]
[Embodiment 2]
In the first embodiment, 0.01 to 2 parts by mass of ultramarine is contained per 100 parts by mass of the binder resin.
[0168]
[Embodiment 3]
In Embodiment 1 or 2, the storage elastic modulus (G ′) of the toner at 80 ° C.₈₀) Is 1 × 10⁶~ 1 × 10⁸[DN / m²Loss tangent (tan δ) represented by the ratio (G ″ / G ′) of the storage modulus (G ′) and the loss modulus (G ″) at a temperature of 140 ° C._G) Is in the range of 0.2 to 1.5, and a loss tangent (tan δ) represented by a ratio (ε ″ / ε ′) between the dielectric loss factor (ε ″) and the dielectric constant (ε ′)._ε)But,
Frequency 5 × 10⁴In Hz, tan δ_ε(5 × 10⁴Hz) ≦ 0.008
Frequency 1 × 10⁵In Hz, tan δ_ε(1 × 10⁵Hz) ≦ 0.011
The black toner according to claim 1, wherein:
[0169]
[Embodiment 4]
In any one of Embodiments 1 to 3, the toner has one or more endothermic peaks in a temperature range of 30 to 200 ° C. in an endothermic curve in differential thermal analysis (DSC) measurement, The peak temperature of the endothermic peak is in the range of 60 to 110 ° C.
[0170]
[Embodiment 5]
In any one of Embodiments 1 to 4, the binder resin is
(A) polyester resin,
(B) a hybrid resin having a polyester unit and a vinyl polymer unit,
(C) a mixture of the hybrid resin of the above (b) and a vinyl polymer,
(D) a mixture of a polyester resin and a vinyl polymer,
(E) Mixture of the above-mentioned (b) hybrid resin and polyester resin
Is a resin selected from the group consisting of:
[0171]
[Embodiment 6]
In any one of Embodiments 1 to 5, the release agent is contained in an amount of 1 to 20 parts by mass based on 100 parts by mass of the resin component in the toner.
[0172]
[Embodiment 7]
In any one of Embodiments 1 to 6, the weight average particle diameter of the toner is 4 to 10 μm.
[0173]
【Example】
Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.
[0174]
(Ultra Marine)
Table 1 shows the ultramarine used in this example.
[0175]
[Table 1]

[0176]
[Production of hybrid resin]
As a vinyl monomer composition,
Styrene 1.9mol
0.21 mol of 2-ethylhexyl acrylate
Fumaric acid 0.15mol
α-Methylstyrene dimer 0.03 mol
Dicumyl peroxide 0.05 mol
Was placed in a dropping funnel. Also,
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) p
Lopan 7.0 mol
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) pro
Bread 3.0 mol
Terephthalic acid 3.0 mol
2.0 mol of trimellitic anhydride
Fumaric acid 5.0 mol
Dibutyltin oxide 0.2g
Was placed in a glass 4-liter four-necked flask, fitted with a thermometer, a stirring rod, a condenser, and a nitrogen inlet tube, and placed in a heating mantle. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and while stirring at a temperature of 145 ° C., the vinyl-based monomer composition was dropped from the dropping funnel over 4 hours. Next, the temperature was raised to 200 ° C., and the mixture was reacted for 4 hours to obtain a hybrid resin. Table 2 shows the results of the molecular weight measurement by GPC.
[0177]
[Production of polyester resin]
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) p
Lopan 3.6 mol
Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) pro
1.6 mol bread
1.7 moles of terephthalic acid
Trimellitic anhydride 1.1 mol
2.4 mol of fumaric acid
0.1 g of dibutyltin oxide
Was placed in a glass 4-liter four-necked flask, fitted with a thermometer, a stirring rod, a condenser, and a nitrogen inlet tube, and placed in a heating mantle. The mixture was reacted at 215 ° C. for 5 hours under a nitrogen atmosphere to obtain a polyester resin. Table 2 shows the results of the molecular weight measurement by GPC.
[0178]
(Production of vinyl polymer)
2.2 mol of styrene
0.23 mol of 2-ethylhexyl acrylate
Dicumyl peroxide 0.08 mol
3.2 g of dibutyltin oxide
Was placed in a 3 liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a falling condenser, and a nitrogen inlet tube, and reacted while stirring at 225 ° C. in a nitrogen atmosphere in a mantle heater to obtain a vinyl system. A polymer was obtained. Table 2 shows the results of the molecular weight measurement by GPC.
[0179]
[Table 2]

[0180]
〔Release agent〕
In this example, purified n-paraffin wax having a melting point of 67.2 ° C. was used as a release agent.
[0181]
〔Carbon black〕
Table 3 shows the carbon blacks used in this example.
[0182]
[Table 3]

[0183]
[Production of toner and developer]
After sufficiently premixing the toner materials shown in Table 4 with a Henschel mixer, the mixture was melt-kneaded with a twin-screw extruder, cooled, and ground to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified by a multi-segment classifier to obtain toner particles having a weight average particle size of 7.0 μm.
[0184]
With respect to 100 parts by mass of the toner particles, nC₄H₉Si (OCH₃)₃Treated with titanium oxide (BET specific surface area: 110m)²/ G) A toner was prepared by combining 1.0 parts by mass. Further, the toner and magnetic ferrite carrier particles (average particle size: 50 μm) whose surface was coated with a silicone resin were mixed so that the toner concentration became 6% by mass to obtain a two-component developer.
[0185]
[Table 4]

[0186]
〔Evaluation method〕
Endurance test of 20,000 continuous copies using a commercially available plain paper full-color copying machine (Canon “CLC900”) at room temperature and normal humidity (23 ° C / 60%), using an original document with an image area ratio of 25% Was done.
[0187]
(1) Developability (image density)
Developability was evaluated based on the change in image density at the initial stage of durability and after 20,000 copies. The image density was measured using a Macbeth densitometer manufactured by Macbeth Co., Ltd., with the solid portion of the original image (toner application amount per unit area: 0.6 mg / cm.²) Was averaged five times, and the change in image density was observed.
[0188]
(2) Fog
The whiteness of the white background was measured with a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), and the fog density (%) was calculated and evaluated from the difference between the whiteness and the whiteness of the transfer paper. The evaluation criteria are as follows.
A: Very good (less than 1.0%)
B: good (1.0% to less than 2.0%)
C: Normal (2.0% to less than 3.0%)
D: Bad (3.0% or more)
[0189]
(3) Fixing temperature range
A fixing test was performed by removing the oil application mechanism of a color copying machine (“CLC900” manufactured by Canon Inc.) and modifying the fixing device so that the fixing temperature could be freely set. At this time, the image area ratio was 25%, and the amount of applied toner per unit area was 0.6 mg / cm.²Set to. The measurement of the fixing start temperature and the offset occurrence temperature is performed by adjusting the set temperature of the fixing unit every 5 ° C. within a temperature range of 120 to 210 ° C., outputting a fixed image at each temperature, and dividing the obtained fixed image by four. .9 kPa (50 g / cm²The fixing temperature at which the density reduction rate before and after the rubbing was 10% or less was determined as the fixing start temperature. The set temperature was further increased from the fixing start temperature, and the temperature at which the high-temperature offset occurred visually was taken as the offset occurrence temperature.
[0190]
(4) Storage (blocking resistance)
The toner was left in an oven at 50 ° C. for one week, and the level of cohesiveness was visually determined. The evaluation criteria are shown below.
A: No aggregates are observed at all, and the fluidity is very good.
B: Some aggregates are seen, but loosened immediately.
C: Aggregates are loosened by the developer stirring device (normal).
D: Aggregates are not loosened (slightly bad) in the developer stirring device.
[0191]
(Examples 1 to 8)
Very good developability was exhibited even after the running of 20,000 sheets, and no fogging occurred. Further, it was excellent in low-temperature fixing property and high-temperature offset resistance, and a wide fixing temperature range could be obtained. Table 5 shows the results.
[0192]
(Examples 9 and 10)
Although the fixing start temperature was slightly higher than in Example 1, there was no problem in use. Further, in Example 9, although the storage stability was slightly disadvantageous, it was at a level without any problem. Table 5 shows the results.
[0193]
(Example 11)
Very good developability was exhibited even after the running of 20,000 sheets, and no fogging occurred. Further, it was excellent in low-temperature fixing property and high-temperature offset resistance, and a wide fixing temperature range could be obtained. Table 5 shows the results.
[0194]
(Example 12)
Compared with Example 1, the image density was low because the amount of carbon black was small, but good developability was exhibited, no fogging occurred, and there was no problem in use. Table 5 shows the results.
[0195]
(Example 13)
As compared with Example 1, the amount of carbon black was larger and tan δ_εWas slightly worse, but good images were obtained. Table 5 shows the results.
[0196]
(Example 14)
Compared with Example 1, the fixing temperature range was slightly narrowed, probably because of the small amount of wax. Table 5 shows the results.
[0197]
(Example 15)
Compared with Example 1, fog and storage stability were slightly deteriorated, and the obtained image was slightly reddish, but there was no problem in use. Table 5 shows the results.
[0198]
(Example 16)
Compared with Example 1, the fog was slightly worse and the image density was low, but there was no problem in use. Table 5 shows the results.
[0199]
(Example 17)
Compared with Example 1, the fog was slightly worse and the image density was low, but there was no problem in use. Table 5 shows the results.
[0200]
(Comparative Example 1)
The particle size of the ultramarine used was small, and it was considered that sulfur as a component was released. After durability, the image density decreased and fog occurred. Table 5 shows the results.
[0201]
(Comparative Example 2)
Since the used ultramarine has a large particle size and a large amount of sieve residue, aggregation is considered to have occurred, and tanδ_εAnd the fogging also occurred. Table 5 shows the results.
[0202]
(Comparative Example 3)
Because of the small amount of carbon black added, a sufficient image density could not be obtained. Table 5 shows the results.
[0203]
(Comparative Example 4)
Since the added amount of carbon black was too large, fogging was remarkable, and the image density after running was reduced. Table 5 shows the results.
[0204]
(Comparative Example 5)
Since the low softening point substance was not used, the recording material was wound around the fixing roller. Table 5 shows the results.
[0205]
(Comparative Example 6)
Since ultramarine was not used, the dispersibility of carbon black was poor, and tanδ_εThe values were poor, and good results were not obtained in all of the image density, fog, and fixing temperature range. Table 5 shows the results.
[0206]
[Table 5]

[0207]
【The invention's effect】
As described above, in the present invention, because of the excellent dispersibility of carbon black and the release agent due to the addition of ultramarine, it has a high coloring power covering a dynamic range from low to high concentrations, and has fixability, A toner having excellent storage stability and heat resistance is provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus to which the toner of the present invention can be applied.
FIG. 2 is an enlarged view of a heat fixing device of the image forming apparatus of FIG.
[Explanation of symbols]
1 Photoconductor drum
1a Substrate
1b Photoconductor
2 Primary charger (charging means)
2a shield
2b Discharge wire
2c grid
3 Exposure means
3a Polygon mirror
3b lens
3c mirror
4 Developing device (developing means)
4Y, 4C, 4M, 4Bk developing unit
4a Developing sleeve
4b Eccentric cam
5 Transfer device
5a Transfer drum (recording material carrier)
5b Transfer charger (transfer charger)
5c adsorption charger
5d suction roller
5e Inside charger
5f Outside charger
5g recording material carrying sheet
6 cleaning device
6a Cleaning blade
6b Cleaning container
7 Pre-exposure lamp
8 Paper feeder
8a Paper cassette
8b paper feed roller
8c Registration roller
9 Separation means
9a Separate charger
9b Separating claw
9c Separation roller
10 Heat and pressure fixing device
10a Fixing roller
10b Pressure roller
11 Paper output unit
11a Transfer path switching guide
11b Discharge roller
11c Output tray
11d transport vertical path
11e Inversion path
11f loading member
11g middle tray
11h transport roller
11j Reverse roller
12a Platen glass
12b Exposure lamp
12c mirror
12d condenser lens
12e full color sensor
13a fur brush
13b, 14b Backup brush
14a Oil removal roller
31, 34 core metal
32 HTV silicone rubber layer
33 Addition type silicone rubber layer
36, 37 Halogen heater
38 Thermistor
39 Control device
40 oil pan
41 Dimethyl silicone oil
42, 50 Oil pump roller
43 Oil application roller
44 Oil application amount adjustment blade
45 Butt Roller
46 Web
I Printer section
II Reader section
C Cleaning device
C1 cleaning blade
D manuscript
E light image
O oil application device
P recording material
S1 potential sensor
S2 concentration sensor

Claims (1)

At least a binder resin, a release agent, 0.5 to 10 parts by mass of carbon black per 100 parts by mass of the binder resin, and ultramarine having a volume average particle size of 0.3 to 3.0 μm. Characteristic black toner.

Images