JP4027240B2 - Black toner - Google Patents

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、Ｒ₁〜Ｒ₇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、−ＮＨ₂、−ＮＨ（ＣＨ₃）、−Ｎ（ＣＨ₃）₂、−ＯＣＨ₃、−Ｏ（Ｃ₂Ｈ₅）、−ＣＯＯＨ、−ＣＯＮＨ₂を示す。〕
【００８９】
上記化合物において、好ましいＲ₁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、露光ランプによって照射され、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（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５×１０⁴Ｈｚと１×１０⁵Ｈｚ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／ｃｍ²）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、１００〜１０⁶Ｈｚ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６×１０²、２．１×１０³、４×１０³、１．７５×１０⁴、５．１×１０⁴、１．１×１０⁵、３．９×１０⁵、８．６×１０⁵、２×１０⁶、４．４８×１０⁶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、１０³〜２×１０⁶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、１０³、１０⁴、１０⁵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（ＲｕＯ₄）、または必要に応じて四酸化オスミウム（ＯｓＯ₄）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１×１０⁶〜１×１０⁸［ｄＮ／ｍ²］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５×１０⁴Ｈｚにおいて、ｔａｎδ_ε（５×１０⁴Ｈｚ）≦０．００８
周波数１×１０⁵Ｈｚにおいて、ｔａｎδ_ε（１×１０⁵Ｈｚ）≦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】

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】

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程度に粗粉砕した。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−Ｃ₄Ｈ₉Ｓｉ（ＯＣＨ₃）₃で処理した疎水性酸化チタン（ＢＥＴ比表面積：１１０ｍ²／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／ｃｍ²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／ｃｍ²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／ｃｍ²）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】
（参考例１）
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】
（参考例２）
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】
（参考例３）
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】
（参考例４）
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]
BACKGROUND OF THE INVENTION
The present invention relates to a black toner for developing an electrostatic image or a black toner of a toner jet type, and does not use oil for preventing high temperature offset, or uses a heat and pressure fixing unit that uses less oil. Also relates to a black toner that can be sufficiently fixed.
[0002]
[Prior art]
In recent years, the proposed full-color copying machine uses four photosensitive members and a belt-like transfer member, and uses cyan toner, magenta toner, yellow toner and black toner for the electrostatic image formed on each photosensitive member. After development, the transfer material (recording material) is transported between the photoreceptor and the belt transfer body and transferred between straight passes, and then a full color image is formed, or electrostatic force is applied to the surface of the transfer body facing the photoreceptor. In general, a method of obtaining a full-color image by winding a transfer material by a mechanical action such as a gripper and performing a development-transfer process four times is used.
[0003]
As the toner applied to these full-color copying machines, each toner is sufficiently mixed in the heat and pressure fixing process without impairing the color reproducibility and the overhead projector (OHP) image transparency (OHP transparency). is required. The full-color image forming toner is preferably a low molecular weight binder resin having sharp melt properties as compared with a general black toner for black and white copying machines. However, generally, when a sharp melt binder resin is used, when the toner is melted in the heat and pressure fixing step, the self-cohesion force of the binder resin is low, and thus a problem with high temperature offset resistance is likely to occur. Therefore, for example, as proposed in Patent Documents 1 to 3, in general black toner for black-and-white copying machines, a relatively high crystal typified by polyethylene wax or polypropylene wax is used to improve high-temperature offset resistance during fixing. -Type wax is used as a release agent.
[0004]
Further, a toner having a specific storage elastic modulus has been proposed in order to improve the offset resistance. For example, Patent Documents 4 and 5 propose toners having a specific storage elastic modulus at 180 ° C. or 170 ° C. However, as a toner for full-color image formation that requires both low-temperature fixing and high-temperature offset resistance, sufficient color mixing characteristics, etc., the toner viscosity is too low and the storage stability under high-temperature and high-humidity environment is satisfactory. It wasn't possible.
[0005]
Further, Patent Documents 6 to 12 propose toners having a specific storage elastic modulus. However, there is still room for improvement in order to secure ideal fixing characteristics as a toner for forming a full-color image and to stably fix the toner for 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 high-temperature offset resistance. However, the fixed image obtained in this manner has excess oil attached to the surface thereof, and has image defects characteristic to oil application such as uneven application and glare due to oil. On the other hand, at the time of double-sided fixing, the oil on the image surface of the first surface that has already been fixed adheres to the photoconductor and may cause new image defects. Furthermore, it has been pointed out that the oil swells the fixing roller and shortens the life of the fixing roller. Further, in this method, in order not to generate oil streaks on the fixed image, it is necessary to supply oil uniformly and quantitatively on the surface of the fixing roller, and the fixing device tends to be enlarged.
[0007]
Therefore, in the heat and pressure fixing means that does not use oil or uses a small amount of oil, there is a great expectation for the toner in which the occurrence of offset is suppressed, and it is strongly combined with a toner having excellent low-temperature fixability. It was long-awaited.
[0008]
On the other hand, when carbon black is used as a colorant, many problems tend to occur as compared with a color toner using a normal organic pigment as a colorant. For example, since carbon black generally has a small primary particle size and a large specific surface area, it is difficult to uniformly disperse in the toner, and free carbon black tends to be generated. Therefore, sufficient charging cannot be performed, and problems such as toner scattering and fogging are likely to occur. In addition, the loose carbon black is liable to cause problems such as sleeve contamination, carrier spent, and drum filming, and long-term durability stabilization has been difficult. Furthermore, since carbon black is generally conductive, the chargeability of the toner is hindered and uniform charging cannot be achieved, resulting in a decrease in uniformity in the halftone image area, and a deterioration in uniform transferability during transfer. There was a problem.
[0009]
In order to solve these problems, for example, Patent Document 13 uses a method of using carbon black whose surface is grafted, and Patent Document 14 discloses a method of using carbon black surface-treated with an aluminum coupling agent. Although these methods have been proposed, the steps for surface treatment of carbon black are complicated and time-consuming, and it is essential to increase the production cost, and it is difficult to adopt them industrially.
[0010]
Regarding the improvement of the dispersibility of carbon black, Patent Documents 15 and 16 propose a method for improving the dispersibility by using a specific dispersant, but it cannot be said that this has been sufficiently solved. Is the situation.
[0011]
Patent Document 17 proposes a black toner composed of carbon black having a relatively high oil absorption amount and an azo iron compound having a specific structure. This is a toner having high coloring power and stable chargeability, but leaves some problems in solid uniformity and durability in 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]
Japanese Unexamined Patent Publication No. 57-52574
[Patent Document 4]
JP-A-11-84716
[Patent Document 5]
Japanese Patent Laid-Open No. 8-54750
[Patent Document 6]
JP-A-5-249735
[Patent Document 7]
JP-A-7-92737
[Patent Document 8]
Japanese Patent Laid-Open No. 7-234542
[Patent Document 9]
JP 7-295298 A
[Patent Document 10]
JP-A-8-234480
[Patent Document 11]
JP-A-8-278662
[Patent Document 12]
Japanese Patent Laid-Open No. 10-171156
[Patent Document 13]
Japanese Patent Laid-Open No. 56-116044
[Patent Document 14]
JP 63-210849 A
[Patent Document 15]
Japanese Patent Application Laid-Open No. 64-35457
[Patent Document 16]
JP-A-1-145664
[Patent Document 17]
Japanese Patent Laid-Open No. 10-186713
[0013]
[Problems to be solved by the invention]
An object of the present invention is to provide a black toner that solves the above-described problems.
[0014]
That is, the present invention provides a black toner that has excellent dispersibility between carbon black and a release agent and has a high coloring power that covers a wide dynamic range from a low concentration to a high concentration.
[0015]
Another object of the present invention is to provide a black toner in which the occurrence of offset is suppressed in a heat and pressure fixing means that does not use oil or uses a small amount of oil.
[0016]
A further object of the present invention is to provide a black toner excellent in low-temperature fixability.
[0017]
Still another object of the present invention is to provide a black toner that is excellent in storage stability, heat resistance, and blocking resistance.
[0018]
Furthermore, an object of the present invention is to provide a black toner having no fog, excellent highlight reproducibility, excellent solid uniformity, and excellent durability stability.
[0019]
[Means for Solving the Problems]
  The present invention comprises at least a binder resin,2 to 10 parts by mass per 100 parts by mass of the binder resinA release agent;SaidContains 0.5 to 10 parts by mass of carbon black per 100 parts by mass of binder resin and ultramarine having a volume average particle size of 0.3 to 3.0 μm.Black toner,
  Storage modulus of the black toner at 80 ° C. (G ′ ₈₀ ) Is 1 × 10 ⁶ ~ 1x10 ⁸ [DN / m ² Loss tangent (tan δ) represented by the ratio (G ″ / G ′) of storage elastic modulus (G ′) and loss elastic modulus (G ″) at a temperature of 140 ° C. _G ) Is in the range of 0.2 to 1.5, and the loss tangent (tan δ) represented by the ratio (ε ″ / ε ′) between the dielectric loss factor (ε ″) and the dielectric constant (ε ′). _ε )But,
Frequency 5 × 10 ^Four In Hz, tan δ _ε (5 × 10 ^Four Hz) ≦ 0.006
Frequency 1 × 10 ^Five In Hz, tan δ _ε (1 × 10 ^Five Hz) ≦ 0.008
IsThis is a black toner.
[0020]
As a result of intensive studies, the present inventors have found the following in the black toner containing ultramarine.
[0021]
By appropriately containing ultramarine, the dispersibility of carbon black is improved, the dispersibility of the release agent is also improved, and charging is stabilized, and excellent image quality and durability are provided. Furthermore, it has also been found that ultramarine has a bluing effect (increased blackness) as an additive and has a high coloring power.
[0022]
That is, a toner having excellent coloring power and charging performance can be obtained as compared with a conventional toner containing carbon black. In addition, heat and pressure fixing means that do not use oil or reduce the amount of oil used have excellent high-temperature offset resistance, and achieve both long-term storage stability and low-temperature fixability in high-temperature environments. It was possible.
[0023]
DETAILED DESCRIPTION OF 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 a detailed study by the present inventors, by appropriately incorporating ultramarine in the toner, the dispersibility of the carbon black is improved and the decrease in the resistance of the toner due to the conductivity of the 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 clear but is thought to be as follows.
[0027]
Due to the influence of functional groups 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. Further, carbon black has a small particle diameter and a structure in which carbon is arranged in a network shape, which is a factor for reducing the affinity for the binder resin. However, by incorporating ultramarine as in the present invention, ultramarine acts as a buffer between the binder resin and carbon black, and the affinity between the binder resin and carbon black increases.
[0028]
This is thought to be because ultramarine is an inorganic pigment that is structurally close to zeolite and has high dispersibility in oil-based materials in addition to the inherent hydrophilicity.
[0029]
Therefore, carbon black is present in a state of being wrapped with a binder resin, and the dispersibility in the toner particles is increased, so that it is possible to suppress the uneven distribution of carbon black on the toner surface, and the release of carbon black. Can be suppressed. Furthermore, even if there is carbon black present on the surface of the toner particles, it is covered with the binder resin, so that it does not leak electric charge and can suppress the increase in toner particle conductivity. It becomes. As a result, a toner having a quick and good chargeability can be obtained.
[0030]
Furthermore, due to the buffer action of Ultramarine, not only carbon black but also the dispersibility of the release agent is improved, and not only the above-mentioned coloring power and chargeability are improved, but also transferability and toner fluidity are improved. The knowledge that it improves is obtained.
[0031]
As a result, high and uniform charging with the charging member can be achieved, and an image with excellent halftone reproducibility in a color image can be obtained.
[0032]
Next, the ultramarine used in the present invention will be described.
[0033]
The ultramarine used in the present invention is generally composed of raw materials mainly composed of kaolin, soda ash, sulfur, and a reducing agent, and is obtained through processes such as firing, grinding, drying, and surface processing. It is not intended to limit.
[0034]
The 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, more preferably 0.5 to 1.5 μm. When the volume average particle size is less than 0.3 μm, sulfur in the ultramarine is liberated, which is not preferable. On the other hand, if it is larger than 3.0 μm, the toner is reddish and is not suitable as a black toner.
[0035]
In the present invention, the ultramarine preferably has a pH of 7.5 or more, more preferably 8.5 or more, and further preferably 7.5 to 10.5. Since ultramarine is weakly decomposed into an acid, it is not preferable that the pH is 7.5 or less. On the contrary, if the pH is extremely high, the compatibility with carbon black and resin is lowered and the carbon black is likely to be liberated. Therefore, the pH is preferably 10.5 or less.
[0036]
In the present invention, the 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. When the oil absorption is less than 15 ml / 100 g, the dispersibility of the ultramarine in the toner particles becomes insufficient, so that the dispersibility of the carbon black and the release agent also decreases. On the other hand, when the oil absorption exceeds 40 ml / 100 g, the resistance of the toner tends to decrease, and the charge amount particularly in a high temperature and high humidity environment decreases, and problems such as toner scattering and fogging are likely 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 production method such as furnace black, gas black thermal black, acetylene black, or lamp black, and the production method 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, uniform dispersion is difficult, and as a result, the absolute value of the charge amount of the toner is lowered, which is likely to cause toner scattering and fogging. In addition, if the average primary particle size is less than 14 nm, the toner is reddish and unsuitable as black for forming a full-color image. On the contrary, when the average primary particle size of carbon black is larger than 60 nm, even if it is dispersed well, the coloring power becomes too low, which is not preferable. If a large amount of carbon black having such a large primary particle diameter is added to the toner in order to increase the coloring power, the uniformity of charging is lowered, and it tends to cause fogging in durability under a low temperature and low humidity environment.
[0040]
In the toner of the present invention, it is desirable that the average primary particle size of carbon black measured by TEM (transmission electron microscope) observation is 14 to 60 nm. More specifically, from the cross-sectional photograph of the toner magnified 40,000 times, carbon black that has not formed an aggregate is randomly extracted and analyzed, and the measurement is repeated until the number of sampling exceeds 300 times. The average particle size was determined. Here, a spherical approximation was performed using an image processing apparatus, and the value defined from the obtained diameter was defined as the average primary particle size of carbon black. When measuring the average primary particle size of carbon black directly from the TEM photograph, the average particle size was determined by repeating the measurement until the major axis of the carbon black was the particle size and the number of samplings exceeded 300 times.
[0041]
  The carbon black used in the present invention preferably has a pH of 6.5 or higher, more preferably 7.0 or higher, more preferably 7.5 to 10.5.TheWhen the pH is less than 6.5, functional groups such as carboxyl groups and ketones increase, polyester association becomes strong, and fixing properties tend to be hindered. On the other hand, if the pH is extremely high, the compatibility between the carbon black and the resin is lowered, and the carbon black tends to be 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 with a volatile content greater than 1.5% means that there are many functional groups on the surface of the carbon black, and when this type of carbon black is used, it tends to cause a decrease in charge under high humidity. The solid uniformity tends 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. When the oil absorption exceeds 150 ml / 100 g, the resistance of the toner tends to decrease, the charge amount tends to decrease in durability evaluation under a high temperature and high humidity environment, and problems such as toner scattering and fogging are likely to occur. Furthermore, the uniform transfer property in a low temperature and low humidity environment is lowered, and the image tends to be bulging. 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 be lowered.
[0044]
Further, the carbon black used in the present invention has a specific surface area of 30 to 200 m by nitrogen adsorption.²/ G, more preferably 40 to 150 m.²/ G, preferably 45-120m²/ G. Specific surface area 200m²When it is larger than / g, it is difficult to uniformly disperse, 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 is reddish and is not suitable as a black for forming a full-color image. Conversely, the specific surface area is 30m²When it is less than / g, even if it is dispersed well, the coloring power becomes too low, which is not preferable.
[0045]
Furthermore, the carbon black used in the present invention has a toluene extraction amount of 0.1% or less, preferably 0.05% or less.
[0046]
In the toner of the present invention, the 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 1.0-8.0 mass parts, More preferably, it is 1.5-7.0 mass parts. When the carbon black content 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 this makes it difficult to obtain an image with a high image density. On the other hand, if the carbon black is used in excess of 10 parts by mass, it becomes difficult to control the charge of the toner, and long-term charge stabilization cannot be achieved.
[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~ 1x10⁸[DN / m²More preferably, 1 × 10⁶~ 5x10⁷[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. In recent years, as the output speed of copiers and printers has increased 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 elastic modulus (G ′₈₀) Is 1 × 10⁸[DN / m²] Is larger, the storage stability, heat resistance, and blocking resistance are sufficient, but it is not preferable because sufficient fixability at a low temperature cannot be obtained.
[0048]
Further, a loss tangent (tan δ) represented by a ratio (G ″ / G ′) of storage elastic modulus (G ′) and loss elastic modulus (G ″) at a temperature of 140 ° C._G) Is preferably 0.2 to 1.5, more preferably 0.3 to 1. in order to achieve both sufficient fixability and high temperature offset resistance, and further to obtain an image having uniform gloss. 0. Loss tangent (tan δ_G) Greater than 1.5 is not preferred because sufficient high temperature offset resistance of the toner cannot be obtained. Loss tangent (tan δ_G) Is less than 0.2, the toner cannot be sufficiently fixed, and the color developability of the toner is significantly reduced.
[0049]
Loss tangent represented by the ratio (ε ″ / ε ′) of dielectric loss factor (ε ″) and dielectric constant (ε ′) as an index indicating the degree of dispersibility of carbon black, which is a characteristic of the black toner of the present invention (Tan δ_ε) The smaller this value, the better the dispersibility of carbon black.
[0050]
In the present invention, the frequency is 5 × 10^FourTan δ in Hz_ε(5 × 10^FourHz) is 0.008 or less and 1 × 10^FiveTan δ in Hz_ε(1 × 10^FiveHz) is 0.011 or less, preferably tan δ_ε(5 × 10^FourHz) is 0.006 or less and tan δ_ε(1 × 10^FiveHz) is 0.008 or less.
[0051]
tan δ_ε(5 × 10^FourHz) is greater than 0.008 and tan δ_ε(1 × 10^Five(Hz) is greater than 0.011, the dispersibility of carbon black is inferior and non-uniform, resulting in a broad toner charge distribution, resulting in low image density, fogging, and high humidity due to charge-up under low humidity. This causes problems such as fogging, scattering, and transferability deterioration due to insufficient charge amount.
[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 (b) above and a vinyl polymer,
(D) a mixture of a polyester resin and a vinyl polymer;
(E) A resin selected from any one of the mixture of the hybrid resin and the polyester resin (b) is preferable.
[0053]
In addition, the binder resin preferably has a molecular weight distribution measured by gel permeation chromatography (GPC) having a main peak (Mp) in a region having a molecular weight 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 exceeding 10,000, it is not preferable because sufficient low-temperature fixability of the toner cannot be obtained and the OHP transparency becomes insufficient. Moreover, when Mw / Mn is less than 5.0, it is impossible to obtain good offset resistance.
[0054]
Furthermore, when the hybrid resin having the polyester unit (b) and the vinyl polymer unit 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 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 polymer. A graft copolymer (or block copolymer) is used in which is a trunk polymer and a polyester unit is a branched polymer.
[0055]
When a polyester resin and / or a hybrid resin is used as the binder resin, alcohol and carboxylic acid, carboxylic acid anhydride, 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, 1, 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 trivalent 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, etc. Can be mentioned.
[0057]
Examples of the acid component include 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; Succinic acid substituted with an alkyl group or an anhydride thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof;
[0058]
Among them, in particular, bisphenol derivatives represented by the following general formula (1) are used as diol components, and carboxylic acid components composed of divalent or higher carboxylic acids or acid anhydrides or lower alkyl esters 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 condensation polymerization of these as a black toner for full color image formation has good charging characteristics This is preferable.
[0059]
[Chemical 1]

(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 them include the following. Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-chloro styrene, 3, Styrene and its derivatives such as 4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, 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, fluoride 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, n-methacrylate Α-methylene aliphatic monocarboxylic acid esters such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate Propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-acrylate Acrylic 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-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.
[0061]
In addition, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride, etc. Unsaturated dibasic acid anhydride; maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Alkenyl succinic acid half ester, fumaric acid methyl half ester, mesaconic acid methyl half ester unsaturated dibasic acid half ester; dimethylmaleic acid, dimethyl fumaric acid unsaturated dibasic acid ester; acrylic acid, meta Α, β-unsaturated acids such as rillic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, the α, β-unsaturated acid and lower fatty acids And monomers having a carboxyl group such as alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, acid anhydrides and monoesters thereof.
[0062]
Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) -Methylhexyl) Monomers having a hydroxy group such as styrene.
[0063]
In the toner of the present invention, the vinyl polymer and / or the vinyl polymer unit of the hybrid resin used as the binder resin may have a crosslinked structure crosslinked with a crosslinking agent having two or more vinyl groups. Good. Examples of the crosslinking agent used in this case include divinylbenzene and divinylnaphthalene as aromatic divinyl compounds; examples of diacrylate compounds linked by an alkyl chain include ethylene glycol diacrylate and 1,3-butylene glycol diene. Examples include acrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate and those obtained by replacing acrylate of the above compounds with methacrylate; ether Examples of diacrylate compounds linked by an alkyl chain containing a bond include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene, and the like. Glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate and the above compounds in which acrylate is replaced by methacrylate; di-linked by a chain containing an aromatic group and an ether bond Examples of acrylate compounds include polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate and What replaced the acrylate of the above compound with the methacrylate is mentioned.
[0064]
Polyfunctional cross-linking agents include pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of the above compounds in place of methacrylate; triallylcia Examples include nurate and triallyl trimellitate.
[0065]
In the present invention, it is preferable that a monomer component capable of reacting with both resin components is contained in the vinyl polymer component and / or the polyester resin component. Examples of monomers that can react with the vinyl polymer among the monomers constituting the polyester resin component include 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 that 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 vinyl polymer and the polyester resin listed above is present, either one or A method obtained by polymerizing both resins is preferred.
[0067]
Examples of the polymerization initiator used in producing the vinyl polymer and the vinyl polymer unit according to the present invention include 2,2′-azobisisobutyronitrile, 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-butyl cumyl 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-isopropyl peroxide -Bonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxycarbonate, di-methoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxy Butyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, tert-butylperoxyacetate, tert-butylperoxyisobutyrate, tert-butylperoxyneodecanoate, tert-butylperoxy-2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, di-tert-butyl peroxyisophthalate, ter - butylperoxy allyl carbonate, tert- amyl peroxy 2-ethyl hexanoate, di -tert- butyl peroxy hexahydro terephthalate, include di -tert- butyl peroxy azelate.
[0068]
As a manufacturing method of the hybrid resin used for this invention, the manufacturing method shown to the following (1)-(6) can be mentioned, for example.
[0069]
(1) A method in which a vinyl polymer, a polyester resin, and a hybrid resin component are blended after production. 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. The ester compound used can be used.
[0070]
(2) A method of producing a polyester unit and a hybrid resin component in the presence of a vinyl polymer unit in the presence of the vinyl polymer unit. The hybrid resin component is produced by a reaction between a vinyl polymer unit (a vinyl monomer can be added if necessary) and a polyester monomer (alcohol, carboxylic acid) and / or polyester. Also in this case, an organic solvent can be appropriately used.
[0071]
(3) A method for producing a vinyl polymer unit and a hybrid resin component in the presence of the polyester unit after the production thereof. 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 units and / or polyester units are produced by adding vinyl monomers and / or polyester monomers (alcohol, carboxylic acid) and performing addition polymerization and / or polycondensation reaction. Is done. In this case, as the hybrid resin component, those produced by the production methods (2) to (4) can be used, and those produced by a known production method can be used as necessary. Furthermore, an organic solvent can be used as appropriate.
[0074]
(6) A vinyl polymer unit, a polyester unit, and a hybrid resin component are produced by mixing a vinyl monomer and a polyester monomer (alcohol, carboxylic acid, etc.) and continuously performing addition polymerization and condensation polymerization reaction. Furthermore, an organic solvent can be used as appropriate.
[0075]
In the production methods of (1) to (5) above, a polymer unit having a plurality of different molecular weights and crosslinking degrees can be used as the vinyl polymer unit and / or the polyester unit.
[0076]
The glass transition temperature of the binder resin used in the toner of the present invention is preferably 40 to 90 ° C, more preferably 45 to 85 ° C. The acid value of the binder resin is preferably 1 to 40 mgKOH / g.
[0077]
Next, the mold release agent used in the present invention will be described.
[0078]
As the release agent used in the present invention, one or two or more kinds of waxes are desirable.
[0079]
The toner of the present invention containing the wax has one or more in a temperature range of 30 to 200 ° C. in an endothermic curve in differential thermal analysis (DSC) measurement from the viewpoint of achieving both low-temperature fixability and blocking resistance. It has an endothermic peak, and the peak temperature of the maximum endothermic peak in the endothermic peak is preferably in the range of 60 to 110 ° C. More preferably, the maximum peak of the endothermic curve is in the range of 65 to 100 ° C. When the peak temperature of the maximum endothermic peak is less than 60 ° C., the toner has poor blocking resistance, and conversely, when the peak temperature of the maximum endothermic peak exceeds 110 ° C., the fixability decreases.
[0080]
Examples of the wax used in the present invention include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax, and oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or Those block copolymers: waxes mainly composed of fatty acid esters such as carnauba wax, sazol wax, and montanic acid ester wax, and partially or fully deoxidized fatty acid esters such as deoxidized carnauba wax Etc. In addition, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brandic acid, eleostearic acid, and valinal acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, and seryl alcohol , Saturated alcohols such as melyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis laurin Saturated fatty acid bisamides such as acid amide and hexamethylene bis stearic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N ′ Unsaturated fatty acid amides such as dioleyl sebacic acid amide; aromatic bisamides such as m-xylene bisstearic acid amide and N, N′-distearylisophthalic acid amide; calcium stearate, calcium laurate, zinc stearate, stearin Aliphatic metal salts such as magnesium acid (generally called metal soap); waxes grafted with aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; behenic acid monoglycerides, etc. Examples include partially esterified products of fatty acids and polyhydric alcohols; methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.
[0081]
In addition to the above, examples of the wax preferably used in the present invention include aliphatic hydrocarbon waxes. 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; synthesis gas containing carbon monoxide and hydrogen Synthetic hydrocarbon waxes obtained from the distillation residue of hydrocarbons obtained by the method or by hydrogenation thereof are preferred. Furthermore, what carried out the fractionation of the hydrocarbon wax by the use of the press perspiration method, the solvent method, the vacuum distillation, or the fractional crystallization method is more preferably used. The base hydrocarbon is synthesized by the synthesis of carbon monoxide and hydrogen using a metal oxide catalyst (mostly two or more multi-component systems) [for example, the Gintoll method, Hydrocol method (with a fluid catalyst bed). Hydrocarbon compounds synthesized by use); hydrocarbons with up to several hundred carbon atoms obtained by the age method (using the identified catalyst bed) from which a large amount of wax-like hydrocarbons can be obtained; alkylene such as ethylene by Ziegler catalyst Polymerized hydrocarbons are preferred because they are linear hydrocarbons with little branching, small and long saturation. In particular, a wax synthesized by a method that does not rely on polymerization of alkylene is also preferred from its molecular weight distribution.
[0082]
In the molecular weight distribution of the wax, the main peak is preferably in the region of molecular weight 400-2400, more preferably in the region of 430-2000. By giving such a molecular weight distribution, it is possible to impart preferable thermal characteristics to the toner.
[0083]
In the present invention, the wax used as a 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 increased, and the mixture is added and mixed while stirring, or by mixing during kneading.
[0085]
The toner of the present invention may contain a metal compound of an aromatic carboxylic acid derivative for charging stabilization. This not only functions as a charge control agent but also contributes to an improvement in 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 not clear, but the cross-linking reaction proceeds partially due to the interaction between the binder resin and the metal compound of the aromatic carboxylic acid derivative, and kneading It is considered that the dispersibility of the hard-dispersible carbon black was increased by increasing the share of the carbon black at the time. Furthermore, since the metal compound of the aromatic carboxylic acid derivative surrounds the carbon black and functions like a dispersion stabilizer for the carbon black, it exerts an effect in stabilizing the carbon black finely dispersed during the kneading and is a reaggregation inhibitor. It seems to be functioning as well.
[0087]
Examples of the aromatic carboxylic acid include three types of compounds represented by the following formulas (2) to (4).
[0088]
[Chemical 2]

[In the above formula, R₁~ R₇Are each hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, -OH, -NH₂, -NH (CH_Three), -N (CH_Three)₂, -OCH_Three, -O (C₂H_Five), -COOH, -CONH₂Indicates. ]
[0089]
In the above compound, preferred R₁Examples thereof 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]
The metal compound of an aromatic carboxylic acid is prepared by, for example, dissolving an aromatic carboxylic acid in an aqueous sodium hydroxide solution, dropping an aqueous solution in which a divalent or higher valent metal atom is melted into the aqueous sodium hydroxide solution, stirring with heating, 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 synthesis method described above.
[0091]
The amount of the aromatic carboxylic acid metal compound 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 viscoelastic characteristics and triboelectrification characteristics of the toner. 5 to 8 parts by mass. When the amount of the metal compound used is less than 0.5 parts by mass, not only does not function 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 proceeds excessively and the fixing property as a toner is impaired.
[0092]
In the present invention, a compound other than the metal compound of the 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 used in a mixer such as a Henschel mixer. After mixing, use a heat kneader such as a heating roll, kneader, or extruder to melt, knead and knead to disperse the carbon black in the resin so that they are compatible with each other. Further, black toner particles can be obtained by performing strict classification.
[0094]
In the present invention, in order to improve the dispersion state of 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 no pressure or under pressure. The first binder resin is melted by heating with heating, and then the first kneaded material is sufficiently kneaded with a kneader such as a three roll, and then the second binder resin is added to the first kneaded material. Further, if necessary, a mixture to which an additive such as a charge control agent or a release agent is added is heated and melt-kneaded to obtain a second kneaded product. After cooling the obtained second kneaded product, It is preferable to classify the toner. Here, the first binder resin and the second binder resin may be the same or different resins.
[0095]
Further, examples of the kneading apparatus include a heating kneader, a single screw extruder, a twin screw extruder, and the like, and particularly preferably a heating kneader.
[0096]
The black toner of the present invention preferably has a weight average particle diameter of 4 to 10 μm and a number average particle diameter of preferably 3.5 to 9.5 μm. Further, the number of particles having a particle size of 4 μm or less in the number distribution of the toner is preferably 5 to 50% by number, and the particle having a particle size of 12.70 μm or more in the volume distribution is preferably 5% by volume or less.
[0097]
When the weight average particle diameter of the toner is larger than 10 μm, it means that there are few fine particles that can contribute to high image quality, and it is easy to obtain a high image density and has the advantages of excellent toner fluidity. It is difficult to adhere faithfully on the fine electrostatic image above, and the reproducibility of the highlight portion is lowered, and the resolution is also lowered. Further, there is a tendency that the toner is excessively applied to the electrostatic charge image more than necessary, and the toner consumption is likely to increase.
[0098]
On the other hand, when the weight average particle diameter of the toner is smaller than 4 μm, the charge amount per unit weight of the toner becomes high, and the decrease in image density, particularly the decrease in image density under low temperature and low humidity becomes remarkable. Therefore, it is not suitable for applications with a high image area ratio such as graphic images.
[0099]
Further, when the weight average particle size of the toner is smaller than 4 μm, contact charging with a charging member such as a carrier is difficult to be performed smoothly, and toner that cannot be sufficiently charged increases, and fog caused by scattering to a non-image portion increases. Will stand out. In order 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, with toner having a weight average particle diameter of less than 4 μm, toner self-aggregation tends to occur, and uniform mixing with the carrier can be achieved in a short time. In the continuous toner replenishment durability, fogging tends to occur.
[0100]
In the toner of the present invention, toner particles having a particle size of 4 μm or less are preferably 5 to 50% by number, more preferably 5 to 25% by number of the total number of particles. If the number of toner particles having a particle size of 4 μm or less is less than 5% by number, it means that there are few fine toner particles that are essential components for high image quality. As the toner is continuously used, the effective toner particle component decreases, the balance of the particle size distribution of the toner shown in the present invention deteriorates, and the image quality gradually decreases.
[0101]
Further, when the number of toner particles having a particle diameter of 4 μm or less exceeds 50% by number, agglomerates between the toner particles tend to occur, and the toner particles often behave as a lump of toner having the original particle diameter. An image is likely to be formed, the resolution is lowered, or the density difference between the edge portion and the inside of the electrostatic charge image is increased, and the image tends to be hollow. Furthermore, it is preferable for the improvement of image quality that the particle size is 12.70 μm or more is 5% by volume or less.
[0102]
Further, it is preferable that a fluidity improver is externally added to the toner of the present invention in terms of image quality improvement and storage stability even in 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 silane coupling agents, titanate coupling agents, aluminum coupling agents, and zircoaluminate coupling agents.
[0104]
Specifically, for example, as a silane coupling agent, a general formula
R_m-Si-Y_n
[In the above formula, 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. ]
The thing represented by these is preferable. 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 processing amount is preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass with respect to 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})_Three
[In the above formula, n represents an integer of 4 to 12, and m represents an integer of 1 to 3. ]
It is an alkyl alkoxysilane coupling agent shown by these. In the alkylalkoxysilane coupling agent, when n is smaller than 4, the treatment becomes easy, but the degree of hydrophobicity is low, which is not preferable. When n is larger than 12, hydrophobicity is sufficient, but coalescence of titanium oxide fine particles increases, and fluidity imparting ability tends to decrease. When m is larger than 3, the reactivity of the alkylalkoxysilane coupling agent is lowered and it becomes difficult to perform hydrophobicity well. As for a more preferable alkyl alkoxysilane coupling agent, n is 4-8 and m is 1-2.
[0107]
The treatment amount of the alkylalkoxysilane coupling agent is preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass with respect to 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 weight, more preferably 0.03 to 3 parts by weight, based on 100 parts by weight of the toner particles.
[0110]
The black toner of the present invention can be applied to both a one-component developer and a two-component developer. Examples of the carrier used when the toner of the present invention is used for a two-component developer include, for example, surface oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth, and alloys thereof. Alternatively, oxide and ferrite can be used.
[0111]
In particular, Mn—Mg—Fe three-element magnetic ferrite particles formed mainly of manganese, magnesium and iron are preferred 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 and a silicone resin is capable of imparting a negative triboelectric charge to the toner of the present invention, environmental stability, carrier This is preferable in terms of suppression of surface contamination.
[0112]
The magnetic carrier preferably has an average particle diameter of 15 to 60 μm, more preferably 25 to 50 μm, in relation to the weight average particle diameter of the toner of the present invention. Examples of the method for adjusting the magnetic carrier to have the average particle diameter include classification by using a sieve. In particular, in order to classify with high accuracy, it is preferable to repeat a plurality of times using an appropriate sieve. It is also an effective means to use a mesh opening whose shape is controlled by plating or the like.
[0113]
When the two-component developer is prepared 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 good results are usually obtained. When the toner concentration is less than 2% by mass, the image density tends to be low, and when it exceeds 15% by mass, fog and in-machine scattering tend to increase.
[0114]
An example of an image forming apparatus that forms a full-color image using the black toner of the present invention is shown in FIG. 1, 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 the image of the 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 charge image carrier that is rotationally driven in the direction of arrow R1. Around the photosensitive drum 1, a primary charger (charging means) 2, an exposure means 3, a developing device (developing means) 4, a transfer device 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 / conveying unit 8 for the recording material P is disposed. Further, a separation unit 9 is installed above the transfer device 5. On the downstream side (downstream side in the conveyance direction of the recording material P), a heating and pressure fixing device 10 and a paper discharge unit 11 are arranged.
[0118]
The photoconductor drum 1 has a base 1a on an aluminum drum and an OPC (organic semiconductor) photoconductor 1b covering the surface thereof, and a predetermined process speed (in the direction of arrow R1) by a driving means (not shown). (Circumferential speed).
[0119]
The primary charger 2 is disposed in a shield 2a having an opening at a portion facing the photosensitive drum 1, a discharge wire 2b disposed in parallel to the bus bar of the photosensitive drum 1 inside the shield 2a, and an opening of the shield 2a. And a corona charger having a grid 2c that regulates the charging potential. The primary charger 2 is applied with a charging bias by a power source (not shown), thereby uniformly charging the surface of the photosensitive drum 1 to a predetermined polarity and a predetermined potential.
[0120]
The exposure unit 3 includes a laser output unit (not shown) that emits laser light based on an image signal from the reader unit II described later, a polygon mirror 3a that reflects the laser light, a lens 3b, and a mirror 3c. . The exposure means 3 is configured to expose the photosensitive drum 1 by irradiating the surface of the photosensitive drum 1 with this laser light, and to remove an electric charge of the exposed portion to form an electrostatic latent image. In the apparatus of FIG. 1, the electrostatic latent image formed on the surface of the photosensitive drum 1 is color-separated into four colors of yellow, cyan, magenta, and black based on the image of the original, and corresponds to each color. The electrostatic latent images are sequentially formed.
[0121]
The developing device 4 includes developing devices 4Y and 4C that store toners (developers) of yellow toner, cyan toner, magenta toner, and black toner in order from the upstream side along the rotation direction of the photosensitive drum 1 (in the direction of arrow R1). 4M, 4Bk. Each of the developing devices 4Y, 4C, 4M, and 4Bk includes a developing sleeve 4a that carries a developer having toner for developing the electrostatic charge image formed on the surface of the photosensitive drum 1, and has an electrostatic charge image. A developing device of a predetermined color to be used for the development is selectively arranged at a developing position close to the surface of the photosensitive drum 1 by an eccentric cam 4b. The developer toner carried on the developing sleeve 4a develops the electrostatic image and forms a visible toner image (visible image). The three color developing devices other than the developing device provided for development are retracted from the development position.
[0122]
The transfer device 5 includes a transfer drum (recording material carrier) 5a that carries the recording material P on its surface, a transfer charger (transfer charging means) 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, an inner charger 5e, and an outer charger 5f that are opposed to the adsorption drum 5a, and is rotatably supported in the direction of arrow R5. A recording material carrying sheet 5g made of a dielectric material is integrally stretched in a cylindrical shape in the opening area of the peripheral surface of the transfer drum 5a. As the recording material carrying sheet 5g, a dielectric sheet such as a polycarbonate film is used. 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 6 a that scrapes off residual toner that is not transferred to the recording material P and remains on the surface of the photosensitive drum 1, and a cleaning container 6 b that collects 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 paper feeding / conveying section 8 includes a plurality of paper feeding cassettes 8a for loading and storing recording materials P of different sizes, a paper feeding roller 8b for feeding the recording materials P in the paper feeding cassette 8a, a number of conveying rollers, and a resist. A recording material P having a roller 8c and the like and having a predetermined size is supplied to the transfer drum 5a.
[0126]
The separating unit 9 includes a separation charger 9a, a separation claw 9b, a separation push-up roller 9c, and the like for separating the recording material P after the toner image is transferred from the transfer drum 5a.
[0127]
The heat and pressure fixing device 10 includes a fixing roller 10a having a heater inside, and a pressure roller 10b that is disposed below the fixing roller 10a and presses the recording material P against the fixing roller 10a.
[0128]
The paper discharge unit 11 includes a conveyance path switching guide 11a, a discharge roller 11b, a paper discharge tray 11c, and the like disposed on the downstream side of the heat and pressure fixing device 10. Further, below the transport path switching guide 11a, a transport vertical path 11d, a reverse path 11e, a stacking member 11f, an intermediate tray 11g, and a transport roller are used to form an image on both sides of one recording material P. 11h, 11i, a reverse roller 11j, and the like are disposed.
[0129]
Further, between the primary charger 2 and the developing device 4 around the photosensitive drum 1, a potential sensor S1 for detecting a charging potential on the surface of the photosensitive drum 1 is provided between the developing device 4 and the transfer drum 5a. Are provided with density sensors S2 for detecting the density of the toner image on the photosensitive drum 1, respectively.
[0130]
Next, the reader unit II will be described.
[0131]
The reader unit II disposed above the printer unit I further reflects the reflected light from the original D, the original table glass 12a on which the original D is placed, the exposure lamp 12b that exposes and scans the image surface of the original D while moving. A plurality of mirrors 12c, a lens 12d that collects the reflected light, a full color sensor 12e that forms a color separation 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 sent to the printer unit I described above.
[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-color full-color images are formed in the order of yellow, cyan, magenta, and black.
[0133]
  The image of the document D placed on the document table glass 12a of the reader unit II is an exposure lamp.InThus, the image is irradiated and color-separated, and a yellow image is first read by the full-color sensor 12e, subjected to predetermined processing, and sent to the printer unit I as an image signal.
[0134]
In the printer unit I, the photosensitive drum 1 is rotationally driven in the direction of the arrow R1, and the surface is uniformly charged by the primary charger 2. Based on the image signal sent from the reader unit II described above, a laser beam is irradiated from the laser output unit of the exposure unit 3, and the surface of the charged photosensitive drum 1 is reflected by the optical image E through the polygon mirror 3a or the like. Exposure. Charges are removed from the exposed portion of the surface of the photosensitive drum 1, 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 electrostatic charge image on the photosensitive drum 1 is made yellow by the developing device 4Y and is visualized to become a yellow toner image. The yellow toner image on the photosensitive drum 1 is transferred to the recording material P carried on the transfer drum 5a. As for the recording material P, the recording material P having a size suitable for the original image is wound around the transfer drum 5a from the predetermined paper feeding cassette 8a via the paper feeding roller 8b, the conveying roller, the registration roller 8c and the like at a predetermined timing. And the yellow toner image on the photosensitive drum 1 is transferred by the transfer charger 5b.
[0135]
On the other hand, after the yellow toner image has been transferred, the toner remaining on the surface of the photosensitive drum 1 is removed by the cleaning device 6, and unnecessary charges are removed by the pre-exposure lamp 7, and the next image formation starting from primary charging is performed. To be served.
[0136]
The processes from reading the original image by the reader unit II to transferring the toner image onto the recording material P on the transfer drum 5a, further cleaning the photosensitive drum 1, and discharging are performed in colors other than yellow, , Cyan, magenta, and black are similarly performed, and toner images of four colors of yellow toner, cyan toner, magenta toner, and black toner are transferred onto the recording material P on the transfer drum 5a so as to overlap each other.
[0137]
The recording material P that has been transferred with the four color toner images 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 with an unfixed toner image supported on the surface. The The recording material P is heated and pressed by the fixing roller 10 a and the pressure roller 10 b of the heating and pressure fixing device 10, the color toner image is melted and fixed, and a full color image is formed on one surface of the recording material P. . The recording material P after fixing is discharged onto the paper discharge tray 11c by the discharge roller 11b.
[0138]
Next, an enlarged view of the heat and pressure fixing device 10 of FIG. 1 is shown in FIG. 2, and the fixing device will be described.
[0139]
In FIG. 2, the fixing roller 10 a in contact with the toner image includes, for example, a 1 mm thick HTV (high temperature vulcanization type) silicone rubber layer 32 on an aluminum core 31, and a specific addition type silicone rubber layer 33 on the outside. And has a diameter of 60 mm.
[0140]
On the other hand, the pressure roller 10b is formed to have a diameter of 60 mm, for example, by providing a 1 mm thick HTV and the above-mentioned specific addition type silicone rubber layer 35 having a thickness of 1 mm on an aluminum cored bar 34. .
[0141]
The above-described fixing roller 10a is provided with a conveying roller heater 36 as a heat generating means in the core metal 31, and the pressure roller 10b is similarly provided with a heater 37 in the core metal 34 so that both surfaces of the recording material P are provided. Heating is performed from The temperature of the pressure roller 10b is detected by the thermistor 38 that is in contact with the pressure roller 10b, and the Halon heaters 36 and 37 are controlled by the control device 39 based on the detected temperature, so that the fixing roller 10a and the pressure roller 10b are controlled. Are controlled to be kept constant at a predetermined temperature. The fixing roller 10a and the pressure roller 10b are pressurized with 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 passes the dimethyl silicone oil 41 in the oil pan 40 through the oil pumping rollers 50 and 42 and the oil application roller 43 and regulates the oil application amount with the oil application amount adjusting blade 44 so as to contact the fixing roller 10a. The surface of the fixing roller 10a is cleaned by the web 46 in contact therewith.
[0143]
In the fixing device 10 described above, the recording material P carrying the unfixed toner image on the surface is nipped and conveyed in the fixing nip between the fixing roller 10a and the pressure roller 10b, and at this time, the recording material P is heated and pressed from both the front and back surfaces. The toner is fixed. At this time, the toner adhering 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 for forming a full color image on only one side of the recording material has been described above. Next, a method for forming this full color image on both sides of the recording material will be described.
[0145]
When full-color images are formed on both sides of the recording material P, the heating and pressure fixing device 10 immediately drives the transported path switching guide 11a after the discharged recording material P, passes through the transporting path 11d, and then into the reversing path 11e. Once guided, the reversing roller 11j is reversed so that the rear end of the reversing roller 11j is used as the head, and the retreating roller 11j is retreated in the direction opposite to the fed direction, and is stored in the intermediate tray 11g. Thereafter, the recording material P having a full color image on one side of the intermediate tray 11g is sent to the transfer drum 5a, and the color toners of yellow toner, cyan toner and magenta toner are transferred to the other side again by the above-described image forming process. Further, black toner is transferred. Since the full color image of the recording material P comes into contact with the transfer drum 5a, the silicone oil adhering to the full color image surface at the time of fixing adheres to the transfer drum 5a and normally tends to hinder the transfer process. Since the silicone oil has excellent absorbability, the amount of silicone oil adhering to the transfer drum 5a is extremely small compared to the conventional case.
[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 heat and pressure fixing device 10, and the unfixed color toner image is transferred to the other surface of the recording material P. Heat and pressure fixing is performed, and full-color images are formed on both sides of the recording material P. At that time, since the black toner of the present invention has a good dispersion of carbon black and contains an appropriate amount of a release agent, a good image is formed on both sides and recording on the fixing roller 10a and the pressure roller 10b. The wrapping 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 recording material-carrying sheet 5g of the transfer drum 5a is much less contaminated with silicone oil or the like than the conventional one, but the fur brush 13a, the backup brush 13b, and the oil removing roller 14a are used as necessary. And cleaning is performed by the backup brush 14b. 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]
[Measurement method of volume average particle diameter of ultramarine]
Measurement is performed using a laser diffraction / scattering particle size distribution analyzer (“LA-920” manufactured by Horiba).
[0150]
[Measurement method of oil absorption]
The oil absorption of ultramarine is measured by JIS K5101-21, and the oil absorption of carbon black is measured by JIS K6221 A method.
[0151]
[Measurement method of 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]
  [Measurement method of viscoelasticity of toner]
  The toner is pressure-molded into a disk-shaped sample having a diameter of 8 mm and a thickness of about 2 to 3 mm. Next, it sets to a parallel plate, and it heats up gradually within the temperature range of 50-200 degreeC, and performs a temperature dispersion measurement. The heating rate is 2 ° C./min, the angular frequency (ω) is fixed at 6.28 rad / sec, and the distortion is automatic. Temperature on the horizontal axis, storage elastic modulus (G ') on the vertical axis, lossMissed bulletTaking the sex ratio (G ″) and reading the value at each temperature. For the measurement, RDA-II (manufactured by Rheometrics) is used.
[0153]
[Measurement method of dielectric loss tangent of toner]
Using a 4284A Precision LCR meter (manufactured by Hewlett-Packard), after calibration at frequencies of 1 kHz and 1 MHz, a frequency of 5 × 10^FourHz and 1 × 10^FiveThe 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 toner is weighed and 34300 kPa (350 kgf / cm²) Over a period of 2 minutes to form a disc having a diameter of 25 mm and a thickness of 1 mm or less (preferably 0.5 to 0.9 mm) to be 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, in a state where a load of 3.43 N (350 g) was applied, 100 to 10⁶Measure three times in the frequency range of Hz and calculate the average value.
[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 (manufactured by Perkin Elmer).
[0156]
The sample to be measured is precisely weighed 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 rise rate of 10 ° C./min at room temperature and humidity in a measurement temperature range of 30 to 200 ° C. In this temperature raising process, an endothermic peak of the main peak of the DSC curve in the temperature range of 30 to 200 ° C. is obtained.
[0158]
[Measurement method of molecular weight distribution by GPC]
The molecular weight of the 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) as a solvent was passed through the column at this temperature at a flow rate of 1 ml / min, and the sample concentration was adjusted to 0.05 to 0.6% by mass. About 50 to 200 μl of THF sample solution is injected and measured. 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 number of counts (retention time). Examples of standard polystyrene samples for preparing a calibration curve include those manufactured by Tosoh Corporation or Pressure Chemical Co. Made molecular weight 6 × 10²2.1 × 10^Three4 × 10^Three1.75 × 10^Four5.1 × 10^Four1.1 × 10^Five3.9 × 10^Five8.6 × 10^Five2 × 10⁶4.48 × 10⁶It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
[0159]
As column, 10^Three~ 2x10⁶In order to accurately measure the molecular weight region, it is preferable to combine a plurality of commercially available polystyrene gel columns. [Mu] -styragel 500, 10 manufactured by Waters^Three10^Four10^FiveCan be mentioned.
[0160]
[Measurement method of toner particle size distribution]
In the present invention, the average particle size and particle size distribution of the toner are measured using a Coulter Counter TA-II type (manufactured by Coulter), but a Coulter Multisizer (manufactured by Coulter) can also be used. As the electrolytic solution, 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 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 a dispersion process for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toner particles of 2.00 μm or more are measured using the 100 μm aperture as the aperture by the measuring device. Distribution and number distribution were calculated. Then, a weight-based weight average particle diameter (D4) obtained from the volume distribution according to the present invention (the median value of each channel is a representative value for each channel) was obtained.
[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. 00 μm; 8.00 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 32.00-40.30 μm are used.
[0162]
[Measurement method of 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 the toner is sufficiently dispersed in the ultraviolet curable acrylic resin, it is cured by irradiating with ultraviolet rays, and the resulting cured product is exposed using an ultramicrotome, which is then converted to ruthenium tetroxide (RuO)._Four) Or, if necessary, osmium tetroxide (OsO)_Four) Was used for electron staining, and a flaky sample was cut out using an ultramicrotome equipped with a diamond knife, and the cross-sectional layer form of the toner was observed using a transmission electron microscope (TEM). From the cross-sectional photograph of the toner thus obtained (for example, a cross-sectional photograph magnified 40,000 times), carbon black not forming an aggregate is randomly extracted and analyzed, and the number of samplings is 300 times. The measurement was repeated until the average particle size was exceeded.
[0164]
In the present invention, carbon black is approximated to a sphere using an image processing apparatus, and the value defined by the obtained diameter is defined as the average primary particle size (A) of carbon black. When measuring the average primary particle size of carbon black directly from a TEM photograph, the measurement is repeated until the major axis of the carbon black is the particle size, and the number of samplings is more than 300 times to obtain the average primary particle size (B). Asked. In the present invention, the same results were obtained in both (A) and (B).
[0165]
Embodiments of the present invention are shown below.
[0166]
[Embodiment 1]
Containing 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. This is a characteristic black toner.
[0167]
[Embodiment 2]
In Embodiment 1, 0.01-2 mass parts of ultramarine is contained per 100 mass parts 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~ 1x10⁸[DN / m²Loss tangent (tan δ) represented by a ratio (G ″ / G ′) of storage elastic modulus (G ′) and loss elastic modulus (G ″) at a temperature of 140 ° C._G) Is in the range of 0.2 to 1.5, and the loss tangent (tan δ) represented by the ratio (ε ″ / ε ′) of the dielectric loss factor (ε ″) to the dielectric constant (ε ′)._ε)But,
Frequency 5 × 10^FourIn Hz, tan δ_ε(5 × 10^FourHz) ≦ 0.008
Frequency 1 × 10^FiveIn Hz, tan δ_ε(1 × 10^FiveHz) ≦ 0.011
The black toner according to claim 1, wherein the toner is a black toner.
[0169]
[Embodiment 4]
In any one of Embodiments 1 to 3, the toner has one or a plurality of 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 (b) above and a vinyl polymer,
(D) a mixture of a polyester resin and a vinyl polymer;
(E) Mixture of hybrid resin and polyester resin of (b) above
It is resin selected from any one of these.
[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 with respect to 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】
Examples of the present invention will be described below, but the present invention is not limited to these examples.
[0174]
[Ultramarine]
Table 1 shows the ultramarine used in this example.
[0175]
[Table 1]

[0176]

Was placed in a glass 4-liter four-necked flask, and a thermometer, a stir bar, a condenser and a nitrogen inlet tube were attached and placed in a mantle heater. Next, after replacing the inside of the flask with nitrogen gas, the temperature was gradually raised while stirring, and the vinyl monomer composition was dropped from the previous dropping funnel over 4 hours while stirring at a temperature of 145 ° C. Next, the temperature was raised to 200 ° C. and reacted for 4 hours to obtain a hybrid resin. The results of molecular weight measurement by GPC are shown in Table 2.
[0177]

Was placed in a glass 4-liter four-necked flask, and a thermometer, a stir bar, a condenser and a nitrogen inlet tube were attached and placed in a mantle heater. Under a nitrogen atmosphere, reaction was performed at 215 ° C. for 5 hours to obtain a polyester resin. The results of molecular weight measurement by GPC are shown in Table 2.
[0178]
[Production of vinyl polymer]
Styrene 2.2 mol
2-Ethylhexyl acrylate 0.23 mol
Dicumyl peroxide 0.08 mol
3.2 g dibutyltin oxide
Is put into a 3 liter four-necked flask equipped with a thermometer, stainless steel stir bar, flow-down condenser and nitrogen inlet tube, and reacted in a mantle heater with stirring at 225 ° C. in a nitrogen atmosphere. A polymer was obtained. The results of molecular weight measurement by GPC are shown in Table 2.
[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 black used in this example.
[0182]
[Table 3]

[0183]
  [Manufacture of toner and developer]
  After sufficiently premixing the toner materials shown in Table 4 with a Henschel mixer, the mixture is melt-kneaded with a twin screw extruder, and after cooling, the particle size is about 1-2 mm using a hammer mill.CoarseCrushed. Subsequently, it was finely pulverized with an air jet type fine pulverizer. Further, the obtained finely pulverized product was classified by a multi-division classifier to obtain toner particles having a weight average particle size of 7.0 μm.
[0184]
N-C with respect to 100 parts by mass of the toner particles._FourH₉Si (OCH_Three)_ThreeTreated with hydrophobic titanium oxide (BET specific surface area: 110m²/ G) 1.0 part by mass was combined to obtain a toner. Further, the toner and magnetic ferrite carrier particles (average particle diameter: 50 μm) surface-coated with a silicone resin were mixed so that the toner concentration was 6% by mass to obtain a two-component developer.
[0185]
[Table 4]

[0186]
〔Evaluation methods〕
Using a commercially available plain paper full-color copier ("CLC900" manufactured by Canon), normal durability at 23 ° C / 60%, using an original document with an image area ratio of 25%, durability test of 20,000 copies Went.
[0187]
(1) Developability (image density)
The developability was evaluated based on the change in image density after the end of durability and after the end of 20,000 sheets. The image density was measured with a Macbeth densitometer manufactured by Macbeth Co., Ltd. (solid toner amount per unit area: 0.6 mg / cm).²The image density change value was averaged five times and the change value of the image density was observed.
[0188]
▲ 2 ▼ fog
The whiteness of the white portion 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: Poor (3.0% or more)
[0189]
(3) Fixing temperature range
A fixing test was performed by removing the oil application mechanism of the color copier (Canon “CLC900”) and modifying it so that the fixing temperature could be set freely. The image area ratio at this time is 25%, and the applied toner amount per unit area is 0.6 mg / cm.²Set to. The fixing start temperature and the offset generation temperature are measured by adjusting the set temperature of the fixing device every 5 ° C. within a temperature range of 120 to 210 ° C., and outputting a fixed image at each temperature. .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. Further, the set temperature was further raised from the fixing start temperature, and the temperature at which the high temperature offset was visually observed was defined as the offset generation temperature.
[0190]
(4) Storage stability (blocking resistance)
The toner was allowed to stand for 1 week in an oven at 50 ° C., and the level of cohesion was determined visually. The evaluation criteria are shown below.
A: Aggregates are not seen at all, and the fluidity is very good.
B: Some agglomerates are seen, but they are 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 1-8)
Even after the endurance of 20,000 sheets, very good developability was exhibited and no fogging occurred. Moreover, it was excellent in low-temperature fixability and high-temperature offset resistance, and a wide fixing temperature range could be taken. The results are shown in Table 5.
[0192]
(Examples 9 and 10)
Compared with Example 1, the fixing start temperature was slightly higher, but there was no problem in use. Further, in Example 9, the storage stability was slightly disadvantageous, but it was a level with no problem. The results are shown in Table 5.
[0193]
(Example 11)
Even after the endurance of 20,000 sheets, very good developability was exhibited and no fogging occurred. Moreover, it was excellent in low-temperature fixability and high-temperature offset resistance, and a wide fixing temperature range could be taken. The results are shown in Table 5.
[0194]
(Example 12)
Compared to Example 1, since the amount of carbon black was small, the image density was low, but good developability was exhibited, no fogging occurred, and there was no problem in use. The results are shown in Table 5.
[0195]
(Example 13)
Compared to Example 1, the amount of carbon black is large and tan δ_εAlthough the value of was slightly worse, a good image was obtained. The results are shown in Table 5.
[0196]
  (Reference example 1)
  Compared to Example 1, the fixing temperature range was slightly narrowed because the amount of wax was small. The results are shown in Table 5.
[0197]
  (Reference example 2)
  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. The results are shown in Table 5.
[0198]
  (Reference example 3)
  Compared with Example 1, the fog was slightly worse and the image density was low, but there was no problem in use. The results are shown in Table 5.
[0199]
  (Reference example 4)
  Compared with Example 1, the fog was slightly worse and the image density was low, but there was no problem in use. The results are shown in Table 5.
[0200]
(Comparative Example 1)
The particle size of the ultramarine used was small, and it was thought that the component sulfur was liberated. After the endurance, the image density decreased and fogging occurred. The results are shown in Table 5.
[0201]
(Comparative Example 2)
Since the ultramarine used has a large particle size and a large amount of sieve residue, it is thought that aggregation has occurred._εThe value of became worse and fogging occurred. The results are shown in Table 5.
[0202]
(Comparative Example 3)
Since the amount of carbon black added was small, sufficient image density could not be obtained. The results are shown in Table 5.
[0203]
(Comparative Example 4)
Since the amount of carbon black added was excessive, fogging was remarkable and the image density after durability was lowered. The results are shown in Table 5.
[0204]
(Comparative Example 5)
Since no low softening point material was used, the recording material was wound around the fixing roller. The results are shown in Table 5.
[0205]
(Comparative Example 6)
Since no ultramarine was used, the dispersibility of carbon black was poor and tan δ_εThe value was bad, and good results were not obtained in all of the image density, fogging and fixing temperature range. The results are shown in Table 5.
[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 by adding ultramarine, it has a high coloring power covering a dynamic range from a low density to a high density, and has a fixing property. 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 a toner of the present invention can be applied.
FIG. 2 is an enlarged view of a heat fixing unit of the image forming apparatus of FIG.
[Explanation of symbols]
1 Photosensitive 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 Developer
4a Development sleeve
4b Eccentric cam
5 Transfer device
5a Transfer drum (recording material carrier)
5b Transfer charger (transfer charging means)
5c Adsorption charger
5d suction roller
5e Inner charger
5f Outside charger
5g Recording material carrier sheet
6 Cleaning device
6a Cleaning blade
6b Cleaning container
7 Pre-exposure lamp
8 Feeding and conveying section
8a Paper cassette
8b Paper feed roller
8c Registration roller
9 Separation means
9a Separate charger
9b Separation claw
9c Separating roller
10 Heating and pressure fixing device
10a Fixing roller
10b Pressure roller
11 Paper discharge unit
11a Transport path switching guide
11b Discharge roller
11c Paper output tray
11d Transport vertical path
11e Reverse path
11f Loading member
11g Intermediate 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
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 pumping roller
43 Oil application roller
44 Oil application amount adjustment blade
45 Impact roller
46 Web
I Printer section
II Reader
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 (5)

And at least a binder resin, a release agent 2 to 10 parts by weight of the binder resin per 100 parts by weight, the carbon black of the binder resin 100 parts by weight per 0.5 to 10 parts by weight, a volume average particle size A black toner containing 0.3 to 3.0 μm of ultramarine ,
The storage modulus (G ′ ₈₀ ) of the black toner at 80 ° C. is in the range of 1 × 10 ⁶ to 1 × 10 ⁸ [dN / m ² ], and the storage modulus (G ′) and loss elasticity at a temperature of 140 ° C. The loss tangent (tan δ _G ) indicated by the ratio (G ″ / G ′) of the ratio (G ″ ) is in the range of 0.2 to 1.5, and the dielectric loss factor (ε ″) and the dielectric constant (ε ′) The loss tangent (tan δ _ε ) expressed by the ratio (ε ″ / ε ′) of
At a frequency of 5 × 10 ⁴ Hz, tan δ _ε (5 × 10 ⁴ Hz) ≦ 0.006
At a frequency of 1 × 10 ⁵ Hz, tan δ _ε (1 × 10 ⁵ Hz) ≦ 0.008
Black toner, characterized in that it.   The black toner according to claim 1, wherein the ultramarine is contained in an amount of 0.01 to 2 parts by mass per 100 parts by mass of the binder resin. The toner has one or a plurality of endothermic peaks in a temperature range of 30 to 200 ° C. in an endothermic curve in differential thermal analysis (DSC) measurement. The black toner according to claim 1 or 2 , wherein the black toner is in the range of ° C. 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 (b) above and a vinyl polymer,
(D) a mixture of a polyester resin and a vinyl polymer;
(E) black toner according to any one of claims 1 to 3 is a resin selected from any of a mixture of the hybrid resin and the polyester resin described above (b). Black toner according to any one of claims 1 to 4 weight average particle size of the toner is 4 to 10 [mu] m.

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