JP3548392B2 - Image forming method - Google Patents

Description

（式中、Ｒはエチレンまたはプロピレン基であり、ｘ，ｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０〜１０である。）。
【００７６】
また、式（Ｂ）で示されるジオール類；
【００７７】
【化３】

であり、ｘ′，ｙ′は０以上の整数であり、かつ、ｘ′＋ｙ′の平均値は０〜１０である。）
が挙げられる。
【００７８】
２価の酸成分としては、例えばフタル酸、テレフタル酸、イソフタル酸、無水フタル酸などのベンゼンジカルボン酸類又はその無水物、低級アルキルエステル；こはく酸、アジピン酸、セバシン酸、アゼライン酸などのアルキルジカルボン酸類又はその無水物、低級アルキルエステル；ｎ−ドデセニルコハク酸、ｎ−ドデシルコハク酸などのアルケニルコハク酸類もしくはアルキルコハク酸類、又はその無水物、低級アルキルエステル；フマル酸、マレイン酸、シトラコン酸、イタコン酸などの不飽和ジカルボン酸類又はその無水物、低級アルキルエステル；等のジカルボン酸類及びその誘導体が挙げられる。
【００７９】
また、架橋成分としても働く３価以上のアルコール成分と３価以上の酸成分を併用することが好ましい。
【００８０】
３価以上の多価アルコール成分としては、例えばソルビトール、１，２，３，６−ヘキサンテトロール、１，４−ソルビタン、ペンタエリスリトール、ジペンタエリスリトール、トリペンタエリスリトール、１，２，４−ブタントリオール、１，２，５−ペンタントリオール、グリセロール、２−メチルプロパントリオール、２−メチル−１，２，４−ブタントリオール、トリメチロールエタン、トリメチロールプロパン、１，３，５−トリヒドロキシベンゼン等が挙げられる。
【００８１】
また、本発明における３価以上の多価カルボン酸成分としては、例えばトリメリット酸、ピロメリット酸、１，２，４−ベンゼントリカルボン酸、１，２，５−ベンゼントリカルボン酸、２，５，７−ナフタレントリカルボン酸、１，２，４−ナフタレントリカルボン酸、１，２，４−ブタントリカルボン酸、１，２，５−ヘキサントリカルボン酸、１，３−ジカルボキシル−２−メチル−２−メチレンカルボキシプロパン、テトラ（メチレンカルボキシル）メタン、１，２，７，８−オクタンテトラカルボン酸、エンポール三量体酸、及びこれらの無水物、低級アルキルエステル；
次式
【００８２】
【化４】

（式中、Ｘは炭素数１以上の側鎖を１個以上有する炭素数１〜３０のアルキレン基又はアルケニレン基）で表わされるテトラカルボン酸等、及びこれらの無水物、低級アルキルエステル等の多価カルボン酸類及びその誘導体が挙げられる。
【００８３】
本発明に用いられるアルコール成分としては４０〜６０ｍｏｌ％、好ましくは４５〜５５ｍｏｌ％、酸成分としては６０〜４０ｍｏｌ％、好ましくは５５〜４５ｍｏｌ％であることが好ましい。
【００８４】
また３価以上の多価の成分は、全成分中の１〜６０ｍｏｌ％であることも好ましい。
【００８５】
該ポリエステル樹脂も通常一般に知られている縮重合によって得られる。
【００８６】
本発明に係るトナー中には上記結着樹脂成分の他に、該結着樹脂成分の含有量より少ない割合で以下の化合物を含有させてもよい。例えばシリコーン樹脂、ポリウレタン、ポリアミド、エポキシ樹脂、ポリビニルブチラール、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、２種以上のα−オレフィンの共重合体などが挙げられる。
【００８７】
本発明においては、トナーに離型性を与えるために次のようなワックス類を含有させることが好ましい。融点が７０〜１６５℃で、１６０℃における溶融粘度が１０００ｍＰａ・ｓ以下のワックスであり、その具体例としてはパラフィンワックス、、マイクロクリスタリンワックス、フィッシャートロプシュワックス、モンタンワックスやエチレン、プロピレン、ブテン−１、ペンテン−１、ヘキセン−１、ヘプテン−１、オクテン−１、ノネン−１、デセン−１のような直鎖のα−オレフィン及び分岐部分が末端にあるような分岐α−オレフィン及びこれらの不飽和基の位置の異なるオレフィンの単独重合体もしくはこれらの共重合体等が挙げられる。
【００８８】
更に、ビニル系モノマーによりブロック共重合体としたり、グラフト変性などを施した変性ワックスでも良い。
【００８９】
また、上記ワックスの添加量は、結着樹脂１００質量部に対して０．５〜１０質量部であることが好ましく、１〜８質量部であることがより好ましい。尚、２種類以上のワックスを併用して添加しても良い。
【００９０】
これらのワックスは、トナー製造に際し、予め重合体成分中に添加、混合しておくこともできる。その場合は、重合体成分の調製時に、ワックスと高分子量重合体とを溶剤に予備溶解した後、低分子量重合体溶液と混合する方法が好ましい。これにより、ミクロな領域での相分離が緩和され、高分子量成分の再凝集が抑制され、低分子量重合体との良好な分散状態も得られる。
【００９１】
係る重合体溶液の固体濃度は、分散効率、撹拌時の樹脂の変質防止、操作性等を考慮し、５〜７０質量％以下であることが好ましく、高分子量重合体成分とワックスの予備溶液は５〜６０質量％以下、低分子量重合体溶液は５〜７０質量％以下の固体濃度であることが好ましい。
【００９２】
高分子量重合体成分とワックスを溶解又は分散させる方法は、撹拌混合により行われ、撹拌は回分式又は連続式でおこなうのが好ましい。
【００９３】
低分子量重合体溶液を混合する方法は、該予備溶液の固形分量１００質量部に対して、該低分子量重合体溶液を１０〜１０００質量部添加し撹拌混合を行うことが好ましい。この場合、回分式でも連続式でも良い。
【００９４】
本発明に係る樹脂組成物の溶液混合時に用いる有機溶剤としては、例えばベンゼン、トルエン、キシレン、ソルベントナフサ１号、ソルベントナフサ２号、ソルベントナフサ３号、シクロヘキサン、エチルベンゼン、ソルベッソ１００、ソルベッソ１５０、ミネラルスピリット等の炭化水素系溶剤；メタノール、エタノール、ｉｓｏ−プロピルアルコール、ｎ−ブチルアルコール、ｓｅｃ−ブチルアルコール、ｉｓｏ−ブチルアルコール、アミルアルコール、シクロヘキサノール等のアルコール系溶剤；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系溶剤；酢酸エチル、ｎ−酢酸ブチル、セロソルブアセテート等のエステル系溶剤；メチルセロソルブ、エチルセロソルブ、ブチルセロソルブ、メチルカルビトール等のエーテル系溶剤等が挙げられる。これらの中で芳香族溶剤、ケトン系溶剤又は、エステル系溶剤が好ましい。また、これらを混合して用いても差し支えない。
【００９５】
有機溶剤を除去する方法は、重合体の有機溶剤溶液を加熱後、常圧下で有機溶剤の１０〜８０質量％を除去した後、減圧下で、残存溶剤を除去する方法が好ましい。この時、有機溶剤溶液は、用いた有機溶剤の沸点から２００℃の範囲に保持することが好ましい。有機溶剤の沸点を下回ると溶剤留去時の効率が悪いだけでなく、有機溶剤中の重合体に不必要な剪断力がかかったり、各構成重合体の再分散が促進され、ミクロな状態での相分離を起こす場合がある。また、２００℃を超えると重合体が解重合し、分子切断によるオリゴマーが生成し、樹脂組成物内への不純物の混入を招くので好ましくない。
【００９６】
本発明で用いられる荷電制御剤は、環状の縮合物を少なくとも１種以上含有する。
【００９７】
このことによる第一の効果は、帯電の減衰特性が好ましいものになる点である。「帯電の減衰特性が好ましい」とは、具体的には放置した時に帯電が維持されることや、耐久時に過剰な帯電を持たないようにリークさせることを言う。
【００９８】
また、ユニット数が異なる縮合物を少なくとも２種以上含有することが好ましい。いろいろな大きさの縮合物があることにより、大きな分子の間に小さい分子が進入でき、結果的に分子間の電子伝導が変化するためと考えられる。ここで「ユニット数」とは、イミダゾール単位を１ユニットして数え、イミダゾール単位の数をユニット数とする。
【００９９】
また、２種以上含有することにより、現像後のトナーがまとまって挙動することが見出された。２種以上の縮合物を含むことにより、転写性が良好になり、転写時に紙の凹凸に従って起こる転写不良が起こりにくくなる。また、定着工程においても定着飛び散りが低減する。これも、現像後の帯電の減衰と関係していると思われる。
【０１００】
２種以上含有する第二の効果は、合成時の収率が向上し、コストが低下する点である。これは、ユニット数の異なる縮合物はそれぞれ反応に適したモノマーの条件が異なる。よって、反応途中の残存モノマーはそのどれかの条件に適合すれば良いので、反応に寄与しないモノマーが少なくなると考えられる。
【０１０１】
また、ユニット数の異なる縮合物を２種以上含有することにより、得られる粉体の結晶性が低下する。そのため、弱い力で微粒子にすることができ、結果としてトナー樹脂への分散性が向上する。
【０１０２】
これらの効果は、ユニット数が３種以上のとき、より向上し、安定した帯電性が得られる。またこの時、１種の縮合物の存在比が９０％以下であることが好ましく、更には８０％以下であることが好ましく、特には７０％以下であり、更には６０％以下である時に、前述の効果はより顕著に現れるようになる。
【０１０３】
また、従来帯電制御剤として提案されてきたイミダゾール縮合物は、鎖状物である。鎖状の縮合物は、分散性に優れるので、帯電性にやや劣るが、均一な帯電性が得られやすい。環状の化合物は、帯電性に優れるので、高い帯電量が得られる。鎖状物の弊害は、環状の縮合物を用いることで改善される。
【０１０４】
また、鎖状縮合物と環状縮合物を同時に用いると、鎖状物の分散性の良さが活かされ、環状物の帯電性の高さにさらに帯電の立ち上がりの速さも現れてくる。鎖状の構造を有する縮合物は、一般の樹脂と同様に比較的低温から軟化する。この成分と環状の成分が混ざることで結果的に非常に良好な帯電性が得られる。これは以下のような現象であると思われる。環状の成分は、高い帯電性を示す。一方、鎖状の成分は帯電量は高くないが、軟化しやすく、分散性が良い。さらにこの両者は基本的に同じ骨格を有するので親和性があり、微細な混合状態を形成されやすい。すなわち、鎖状の成分が環状の成分の分散助剤となっていると考えられ、そのため均一で高い帯電が達成できるのであろう。
【０１０５】
このように本発明の縮合物をトナー中に含有すると、トナーの帯電量分布が高いレベルで均一なものが得られる。そのため、高温高湿環境はトナー飛散の生じやすい環境であるが、本発明の縮合物を含有することにより、トナー飛散が著しく低減する。
【０１０６】
本発明の縮合物は、イミダゾール類とアルデヒド類を無機アルカリ触媒存在下で、加熱することによって得ることができる。鎖状縮合物、環状縮合物を選択的に得て、その後混合しても良い。選択的に得るためには、無機アルカリの添加条件を調整し、さらに洗浄、抽出の条件を調整すれば良い。複数の無機アルカリを添加することで、ユニット数の異なる縮合物の種類を多くすることができる。鎖状縮合物や環状縮合物の混合物も加熱温度、原料の添加時期、合成濃度等の合成条件、溶媒、アルカリ金属の量、ｐＨを調整することにより種々のものが得られる。合成に使用される溶媒としてはメタノール、エタノール、プロパノール、イソプロパノール、ブタノールなどのアルコール類、エチレングリコール、エチレングリコールアルキルエーテル、プロピレングリコールなどのグリコール類が好ましく用いられる。また、洗浄、抽出に用いることのできる溶媒としては、アセトン、メチルエチルケトン、アルコール、エーテル、ヘキサン、ジオキサン、トルエン、クロロホルム、テトラヒドロフラン、ジメチルスルホキシドなどが挙げられる。
【０１０７】
本発明の鎖状縮合物の末端は、水素原子、アルキル基、ハイドロキシ基を含むアルキル基がよく、高湿環境での帯電量において有利である水素、アルキル基が好ましい。例えば、一般式（ＩＩ）においては、一方がアルデヒドに縮合し、一方は水素、アルキル基、ハイドロキシアルキル基となり、一般式（ＩＶ）においては、一方がイミダゾールに縮合し、一方は水素あるいはハイドロキシ基となる。
【０１０８】
本発明の縮合物中の環状縮合物の存在比は５％以上であるのが好ましい。さらに好ましくは５〜９５％であるのが良い。さらに好ましくは１０％〜９０％である。環状のものが５％より少ないと帯電性向上効果が現れる処方が限定され、１０％以上でないと、負帯電性の強い樹脂での効果が小さくなる。また、鎖状のものが５〜９５％含まれることにより、均一に分散することで現像に適した帯電に速く到達し、現像器に供給されたトナーが素早く入れ替わって消費されるようになる。１０〜９０％含むことにより、特に低湿環境での入れ替わりが速くなる。これにより、耐久した時に劣化したトナーが発生しにくくなり、画質が向上する。また、過剰な帯電を持つトナーの発生（いわゆるチャージアップ）が低減し、画像濃度の推移も安定する。
【０１０９】
なお、ここではユニット数１のものは鎖状縮合物に含むものとする。ユニット数が同じであっても、鎖状縮合物と環状縮合物はユニット数の違うものとして扱う。また、縮合物を構成するそれぞれのユニットの置換基Ｒｎはユニット毎に、異なっていてもよいし、同じであってもよく、その順列も任意で良い。
【０１１０】
また本発明においては、縮合物が下記一般式（Ｉ）、（ＩＩ）、（ＩＩＩ）、（ＩＶ）で表されるユニットを含むことが好ましい。
【０１１１】
【化５】

［式中、Ｒ_１及びＲ_３は水素原子、置換基を有していてもよいアルキル基、置換基を有してもよいアリール基、置換基を有してもよいアルアルキル基又は置換基を有してもよいアリサイクリック基を示し；Ｒ_２は水素原子、置換基を有していてもよいアルキル基、置換基を有してもよいアリール基、置換基を有してもよいアルアルキル基、置換基を有してもよいアリサイクリック基、ハイドロキシ基を有するアルキル基又はハイドロキシ基を有するアルアルキル基を示し；Ｒ_４は水素原子又はハイドロキシ基を示し、式（ＩＩ）及び（ＩＶ）は鎖状縮合物の末端ユニットを表わす。］
本発明の縮合物の構造としては、一般式（Ｉ）〜（ＩＶ）における置換基Ｒｎにおいて、縮合反応を阻害しないものであれば、適用可能である。
【０１１２】
一般式（Ｉ），（ＩＩ）における置換基Ｒ_１では、アルキル基、置換基を有していても良い、アリール基、アラルキル基、アリサイクリック基である場合、帯電量の高さ、帯電の立ち上がりが良好になりやすい。その中でも置換基を有していても良いアルキル基が良く、さらに好ましくは炭素数２１個以下のアルキル基、特には炭素数１〜１５個のアルキル基を有するものが、帯電の維持性が向上するので良い。また、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、シクロヘキシル基、ヘプチル基、ノニル基、ウンデシル基、トリデシル基、ペンタデシル基、フェニル基、ベンジル基を有することにより、適度な帯電量を保持するようになり、転写、定着においても制御がしやすくなる。このことにより転写、定着での画像の乱れが低減する。
【０１１３】
一般式（ＩＩ）における置換基Ｒ_２では、水素原子が好ましいが、その他では、アルキル基、アラルキル基、アリール基が良い。
【０１１４】
一般式（ＩＩＩ），（ＩＶ）における置換基Ｒ_３では、水素原子が好ましいが、その他ではメチル基が縮合反応を阻害せず、トナー性能に有害な不純物が含まれにくいので良い。
【０１１５】
一般式（ＩＶ）における置換基Ｒ_４では、水素原子が好ましいが、その他ではハイドロキシ基、シロキシ基、アルキル基、シリル基が帯電量向上効果があり良い。
【０１１６】
置換基の異なる２種以上のユニットを有する縮合物も好ましい。２種以上用いることにより、得られる粉体の結晶性がくずれ、トナーヘの分散性、帯電の立ち上がり方を調整することができる。組合せとしては、例えば炭素数の異なるアルキル基の組合せが良い。
【０１１７】
本発明において、縮合物のユニット数としては環状のものでは２以上、鎖状のものでは３以上のものを含む必要があり、さらには３〜５０のものがよく、さらには３〜３０がよく、特に分散性の観点から３〜１０個の縮合物を含むことが好ましい。
【０１１８】
本発明の化合物をトナーに含有させる方法としては、トナー内部に添加する方法と外添する方法がある。内添する場合の好ましい添加量としては、結着樹脂１００質量部に対して０．１〜１０質量部、より好ましくは０．５〜５質量部の範囲で用いられる。また、外添する場合は、０．０１〜５質量部が好ましく、特にメカノケミカル的にトナー表面に固着させるのが好ましい。
【０１１９】
また本発明の化合物は、従来の技術で述べたような公知の電荷制御剤と組み合わせて使用することもできる。
【０１２０】
以下に本発明の縮合物の具体的構造を例示する。
【０１２１】
存在比は、分子量分布をＦＤ−ＭＳ（電解脱離質量分析）を用いて測定し、ｍ／ｚピークの強度比を存在比として求める。各ユニットの分子量を計算し、そのユニットで構成される縮合物の分子量を計算し、ユニット構成を求める。
【０１２２】
縮合物（１）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１２３】
【化６】

構造式の一例
【０１２４】
【化７】

【０１２５】
【表１】

【０１２６】
縮合物（２）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１２７】
【化８】

構造式の一例
【０１２８】
【化９】

【０１２９】
【表２】

【０１３０】
縮合物（３）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１３１】
【化１０】

構造式の一例
【０１３２】
【化１１】

【０１３３】
【表３】

【０１３４】
縮合物（４）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１３５】
【化１２】

構造式の一例
【０１３６】
【化１３】

【０１３７】
【表４】

【０１３８】
縮合物（５）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１３９】
【化１４】

構造式の一例
【０１４０】
【化１５】

【０１４１】
【表５】

【０１４２】
縮合物（６）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１４３】
【化１６】

構造式の一例
【０１４４】
【化１７】

【０１４５】
【表６】

【０１４６】
縮合物（７）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１４７】
【化１８】

構造式の一例
【０１４８】
【化１９】

【０１４９】
【表７】

【０１５０】
縮合物（８）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１５１】
【化２０】

構造式の一例
【０１５２】
【化２１】

【０１５３】
【表８】

【０１５４】
縮合物（９）：
以下のユニットから構成される縮合物の混合物
Ａとホルムアルデヒドが出発原料
【０１５５】
【化２２】

構造式の一例
【０１５６】
【化２３】

【０１５７】
【表９】

【０１５８】
縮合物（１０）：
以下の２種のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒドが出発原料
【０１５９】
【化２４】

構造式の一例
【０１６０】
【化２５】

【０１６１】
【表１０】

【０１６２】
縮合物（１１）：
以下の２種のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒドが出発原料
【０１６３】
【化２６】

構造式の一例
【０１６４】
【化２７】

【０１６５】
【表１１】

【０１６６】
縮合物（１２）：
以下の３種のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒドが出発原料
【０１６７】
【化２８】

構造式の一例
【０１６８】
【化２９】

【０１６９】
【表１２】

【０１７０】
縮合物（１３）：
以下の３種のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒドが出発原料
【０１７１】
【化３０】

構造式の一例
【０１７２】
【化３１】

【０１７３】
【表１３】

【０１７４】
縮合物（１４）：
以下の４種のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒドが出発原料
【０１７５】
【化３２】

構造式の一例
【０１７６】
【化３３】

【０１７７】
【表１４】

【０１７８】
縮合物（１５）：
Ａ群、Ｂ群のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒド、アセトアルデヒドが出発原料
【０１７９】
【化３４】

構造式の一例
【０１８０】
【化３５】

【０１８１】
【表１５】

【０１８２】
縮合物（１６）：
Ａ群、Ｂ群のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒド、アセトアルデヒドが出発原料
【０１８３】
【化３６】

構造式の一例
【０１８４】
【化３７】

【０１８５】
【表１６】

【０１８６】
縮合物（１７）：
Ａ群、Ｂ群のユニットから選ばれる少なくとも一つのユニットから構成される縮合物の混合物
連結基のところが水素であるイミダゾールとホルムアルデヒド、アセトアルデヒドが出発原料
【０１８７】
【化３８】

構造式の一例
【０１８８】
【化３９】

【０１８９】
【表１７】

【０１９０】
縮合物（１８）：
以下のユニットから構成される縮合物の混合物
Ａとアセトアルデヒドが出発原料
【０１９１】
【化４０】

構造式の一例
【０１９２】
【化４１】

【０１９３】
【表１８】

【０１９４】
縮合物（１９）：
以下のユニットから構成される縮合物の混合物
Ａとベンズアルデヒドが出発原料
【０１９５】
【化４２】

構造式の一例
【０１９６】
【化４３】

【０１９７】
【表１９】

【０１９８】
縮合物（２０）：
以下のユニットから構成される縮合物の混合物
Ａとプロピオンアルデヒドが出発原料
【０１９９】
【化４４】

構造式の一例
【０２００】
【化４５】

【０２０１】
【表２０】

【０２０２】
本発明のトナーに使用できる着色剤としては、任意の適当な顔料又は染料が挙げられる。例えば顔料として、カーボンブラック、アニリンブラック、アセチレンブラック、ナフトールイエロー、ハンザイエロー、ローダミンレーキ、アリザリンレーキ、ベンガラ、フタロシアニンブルー、インダンスレンブルー等がある。これらは定着画像の光学濃度を維持するために必要な量が用いられ、結着樹脂１００質量部に対し０．１〜２０質量部、好ましくは０．２〜１０質量部の添加量が良い。また、同様の目的で、更に染料が用いられる。例えば、アゾ系染料、アントラキノン系染料、キサンテン系染料、メチン系染料があり、結着樹脂１００質量部に対し０．１〜２０質量部、好ましくは０．３〜１０質量部の添加量が良い。
【０２０３】
また、本発明のトナーにおいては、着色剤として磁性体を用い、磁性トナーとして使用することもできる。
【０２０４】
本発明に用いられる磁性体としては、マグネタイト、マグヘマイト、フェライト等の酸化鉄；鉄、コバルト、ニッケルのような金属あるいはこれらの金属とアルミニウム、コバルト、銅、鉛、マグネシウム、錫、亜鉛、アンチモン、ベリリウム、ビスマス、カドミウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムのような金属の合金及びその混合物が用いられ、その磁性体表面或いは内部にケイ素元素を含有するものが好ましい。
【０２０５】
本発明者等が鋭意検討の結果、磁性体中にケイ素元素を含有させることで、磁性体の粒度分布がそろい、トナー中の磁性体の分散が、ケイ素元素を含有しない時に比べて数段良くなることが明らかになった。また、ケイ素元素を含有した磁性体をトナーに含有させると、平均粒子径１０μｍ以下のトナーにおいても、帯電均一性が向上し、トナー凝集性を抑制できトナーの流動性が向上するため、トナーの摩擦帯電量が向上する。その結果、初期画像濃度が安定し、画像カブリもほとんど問題ないレベルに抑えられることがわかった。
【０２０６】
上記磁性体に含有させるケイ素元素の含有率は、磁性体を基準として、０．０５〜１０質量％であることが好ましい。更に好ましくは０．１〜７質量％であり、望ましくは０．２〜５質量％である。磁性体に占めるケイ素元素の含有量が０．０５質量％より少ないと、ケイ素元素を添加した効果が得られなくなり、トナーの摩擦帯電量が不均一になりやすくなり、画像カブリが増加する。また、１０質量％より多いと画像カブリは良くなるものの、トナー担持体表面を汚染し、画像濃度が低下し、また、ゴーストが発生し易くなる。
【０２０７】
本発明における磁性体中のケイ素元素量は、蛍光Ｘ線分析装置ＳＹＳＴＥＭ３０８０（理学電機工業社製）を使用し、ＪＩＳ Ｋ０１１９「蛍光Ｘ線分析通則」に従って、蛍光Ｘ線分析を行なうことにより測定した。
【０２０８】
本発明に用いる磁性体の形状としては、六面体、八面体、十面体、十二面体、十四面体、あるいはそれ以上の面を有する多面体、針状、鱗片状、球形、不定形なものなどが用いられる。中でも多面体が好ましく用いられる。多面体形状の磁性体の場合には、その形状から物理的にトナー粒子からの脱離を防ぐことができる。
【０２０９】
本発明においてトナーに用いる磁性体は、窒素ガス吸着法によるＢＥＴ比表面積が、１〜４０ｍ^２／ｇ、好ましくは２〜３０ｍ^２／ｇ、更に好ましくは３〜２０ｍ^２／ｇが良い。測定法として、ＢＥＴ法に従って、比表面積測定装置：オートソープ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて比表面積を算出する。
【０２１０】
また、磁性体の飽和磁化としては、７９５．８ｋＡ／ｍの磁場中において、５〜２００Ａｍ^２／ｋｇ、好ましくは１０〜１５０Ａｍ^２／ｋｇの範囲のものを用いる。
【０２１１】
更に、磁性体の残留磁化としては、７９５．８ｋＡ／ｍの磁場中において、１〜１００Ａｍ^２／ｋｇ、好ましくは１〜７０Ａｍ^２／ｋｇの範囲のものを用いる。
【０２１２】
また、磁性体の平均粒子径としては、０．０５〜１．０μｍが好ましく、更に好ましくは０．１〜０．６μｍ、特に好ましくは０．１〜０．４μｍである。
【０２１３】
本発明においてトナーに含有させる磁性体の量は、結着樹脂１００質量部に対して１０〜２００質量部、好ましくは２０〜１７０質量部、更に好ましくは３０〜１５０質量部である。
【０２１４】
本発明において磁性体の形状は、透過型電子顕微鏡及び走査型電子顕微鏡により観察されたものである。
【０２１５】
磁性体の磁気特性は、「振動試料型磁力計ＶＳＭ−３Ｓ−１５」（東英工業社製）を用いて外部磁場７９５．８ｋＡ／ｍの下で測定した値である。
【０２１６】
本発明のトナーにおいては、帯電安定性、現像性、流動性、耐久性向上のため、シリカ微粉末を添加することが好ましい。
【０２１７】
本発明に用いられるシリカ微粉末は、窒素吸着によるＢＥＴ法による比表面積が３０ｍ^２／ｇ以上、特に５０〜４００ｍ^２／ｇの範囲内のものが良好な結果を与える。トナー１００質量部に対してシリカ微粉体０．０１〜８質量部、好ましくは０．１〜５質量部使用するのが良い。
【０２１８】
また、本発明に用いられるシリカ微粉末は、必要に応じ、疎水化、帯電性コントロールなどの目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシラン化合物、その他の有機ケイ素化合物等の処理剤で、或いは種々の処理剤を併用して処理されていることも好ましい。
【０２１９】
本発明のトナーには、必要に応じて他の外部添加剤を添加しても良い。
【０２２０】
例えば、帯電補助剤、導電性付与剤、流動性付与剤、ケーキング防止剤、熱ローラー定着時の離型剤、滑剤、研磨剤等の働きをする樹脂微粒子や無機微粒子などである。
【０２２１】
例えば滑剤としては、テフロン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末等が挙げられ、中でもポリフッ化ビニリデン粉末が好ましい。また研磨剤としては、酸化セリウム粉末、炭化ケイ素粉末、チタン酸ストロンチウム粉末等が挙げられ、中でもチタン酸ストロンチウム粉末が好ましい。流動性付与剤としては、酸化チタン粉末、酸化アルミニウム粉末等が挙げられ、中でも疎水性のものが好ましい。導電性付与剤としては、カーボンブラック粉末、酸化亜鉛粉末、酸化アンチモン粉末、酸化スズ粉末等が挙げられる。またさらに、逆極性の白色微粒子及び黒色微粒子を現像性向上剤として少量用いることができる。
【０２２２】
本発明のトナーを作製するには、結着樹脂、着色剤、イミダゾール誘導体及び必要に応じて磁性体、ワックス、金属塩ないしは金属錯体、顔料又は染料、その他の添加剤等を、ヘンシェルミキサー、ボールミル等の混合機により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ような熱混練機を用いて溶融混練し、冷却固化後粉砕及び分級を行い、更に必要に応じて所望の添加剤をヘンシェルミキサー等の混合機により十分混合し、本発明のトナーを得ることができる。
【０２２３】
次に本発明の現像剤担持体であるスリーブの構成を図１に例示して説明する。
【０２２４】
本発明の現像剤担持体あるスリーブは、円筒状基体と、該基体表面を被覆する被膜層（樹脂層）を有する。該樹脂層１は、結着樹脂４、場合によっては導電性物質２、充填剤３、固体潤滑剤５等を含有し、円筒状基体６上に被覆されている。導電性物質が含有されている場合、樹脂層１は導電性なのでトナーの過剰帯電が防止できる。また充填剤３が含有されている場合には、トナーによる該樹脂１の摩耗を防ぎ、更に充填剤３の帯電付与性により、トナーの帯電も好適にコントロールできる。また、固体潤滑剤５が含有される場合には、トナーとスリーブとの離型性が向上され、その結果トナーのスリーブ上への融着が防止できる。
【０２２５】
本発明のスリーブにおいて、樹脂層に導電性物質を含有させる場合、該樹脂層の体積抵抗が１０^６Ω・ｃｍ以下、好ましくは１０^３Ω・ｃｍ以下であるものがよい。樹脂層の体積抵抗が１０^６Ω・ｃｍを超える場合には、トナーのチャージアップが発生しやすくなり、ブロッチの発生や現像特性の劣化を引き起こすことがある。
【０２２６】
樹脂層の体積抵抗は、構成組成物を塗料とし、絶縁シート上にバーコーターにてコート・乾燥させ、１０ｃｍ×１０ｃｍにカットし、低抵抗率計ロレスター（三菱油化社製）により測定することができる。
【０２２７】
また、該樹脂層の表面粗さは、ＪＩＳ中心線平均粗さ（Ｒａ）で０．２〜３．５μｍの範囲にあることが好ましい。Ｒａが０．２μｍ未満ではスリーブ近傍のトナーの帯電量が高くなりすぎ、鏡映力によりトナーがスリーブ上に引きつけられ、新たなトナーがスリーブから帯電付与を受けられず、現像性が不充分となる。Ｒａが３．５μｍを超えると、スリーブ上のトナーコート量が増加しすぎてトナーが十分な帯電量を得られず、かつ不均一な帯電となり、画像濃度の低下や濃度ムラの原因となる。
【０２２８】
次に該樹脂層１を構成する各材料について説明する。
【０２２９】
図１において導電性物質２としては、例えばアルミニウム、銅、ニッケル、銀等の金属粉体；酸化アンチモン、酸化インジウム、酸化スズ等の金属酸化物；カーボンファイバー、カーボンブラック、グラファイト等の炭素同素体が挙げられる。このうちカーボンブラックは特に電気伝導性に優れ、高分子材料に充填して導電性を付与したり、添加量のコントロールで、ある程度任意の導電度を得ることができるために好適に用いられる。なお、本発明に使用するカーボンブラックの個数平均粒径は１μｍ以下、好ましくは０．０１μｍ〜０．８μｍのものが良い。カーボンブラックの個数平均粒径が１μｍを超える場合には、樹脂層の体積抵抗を制御しづらくなり好ましくない。
【０２３０】
導電性物質の使用量としては、結着樹脂１００質量部に対して、好ましくは０．１〜３００質量部であり、より好ましくは１〜１００質量部である。
【０２３１】
充填剤３としては、例えばアルミナ、アスベスト、ガラス繊維、炭酸カルシウム、炭酸マグネシウム、炭酸バリウム、硫酸バリウム、シリカ、ケイ酸カルシウム等の無機化合物；フェノール樹脂、エポキシ樹脂、メラミン樹脂、シリコーン樹脂、ＰＭＭＡ、メタクリレートのターポリマー（例えばポリスチレン／ｎ−ブチルメタクリレート／シランターポリマー）、スチレン−ブタジエン系共重合体、ポリカプロラクトン；ポリカプロラクタム、ポリビニルピリジン、ポリアミドのような含窒素化合物；ポリフッ化ビニリデン、ポリ塩化ビニル、ポリテトラフルオロエチレン、ポリテトラクロロフルオロエチレン、ペルフルオロアルコキシル化エチレン、ポリテトラフルオロアルコキシエチレン、フッ素化エチレンプロピレン−ポリテトラフルオロエチレン共重合体、トリフルオロクロロエチレン−塩化ビニル共重合体といった高度にハロゲン化された重合体；その他にポリカーボネート、ポリエステル等が挙げられる。このうちシリカ及びアルミナが、それ自身の硬さ及びトナーに対する帯電制御性を有するので好ましく用いられる。
【０２３２】
充填剤の使用量としては、結着樹脂１００質量部に対して、好ましくは０．１〜５００質量部、より好ましくは１〜２００質量部である。
【０２３３】
固体潤滑剤５としては、例えば二硫化モリブデン、窒化硼素、グラファイト、フッ化グラファイト、銀−セレン化ニオブ、塩化カルシウム−グラファイト、滑石が挙げられる。このうちグラファイトは潤滑性と共に導電性を有し、高すぎる電荷を有するトナーを減少させ、現像に好適な帯電量を持たせる働きがあることから好適に用いられる。
【０２３４】
固体潤滑剤の使用量としては、結着樹脂１００質量部に対して、好ましくは０．１〜３００質量部であり、より好ましくは１〜１５０質量部である。
【０２３５】
該導電性物質２、場合によっては該充填剤３や固体潤滑剤５が分散される結着樹脂４としては、フェノール系樹脂、エポキシ系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリカーボネート系樹脂、ポリオレフィン系樹脂、シリコーン系樹脂、フッ素系樹脂、スチレン系樹脂、アクリル系樹脂など公知の樹脂が用いられる。特に熱硬化性もしくは光硬化性の樹脂が好ましい。
【０２３６】
また本発明におけるスリーブ表面の樹脂層中の導電性物質、或いは充填剤や固体潤滑剤を表面に好適に露出させるために、または、表面を平滑化処理して均一な凹凸表面を作るために、後述の磨き加工等の手段により表面を平滑化処理することにより、さらに好ましい性能を付与することが可能である。特に、ベタ黒やハーフトーン画像に発生する縦スジ現象や初期の画像濃度の立上がりに効果があり、特に高温高湿下での効果が大きい。
【０２３７】
本発明において、スリーブの平滑化処理の一例を図２に示しながら作用を説明する。図２（Ａ）において該被膜層（樹脂層）５０１は、固体潤滑剤５０２、導電性物質５０３、充填剤５０４、結着樹脂５０５とを含有し、円筒状基体５０６上に被覆されている。これをフェルトや砥粒の付着した帯状研磨材での磨き加工を施すことで、図２（Ｂ）に示すようにスリーブの表面凹凸を均一に仕上げることができるので、スリーブ上のトナーコート量が均一化し、その結果スリーブとの摩擦帯電を受けたトナーのみが現像領域に搬送されるようになる。従って、上記効果が得られるものと考えられる。
【０２３８】
上記のように平滑化処理を施した後も、コート層表面はＪＩＳ Ｂ ０６０１におけるＲａで０．２〜３．５μｍの範囲の凹凸を保持していることが好ましく、より好ましくは０．３〜２．５μｍ程度である。理由は前記と同様である。
【０２３９】
次に本発明の現像剤担持体である現像スリーブが組み込まれる現像方法について説明する。
【０２４０】
図３において、公知のプロセスにより形成された静電潜像を担持する像保持体、例えば電子写真感光ドラム７は、矢印Ｂ方向に回転される。現像剤担持体としての現像スリーブ１４は、ホッパー９から供給された一成分磁性現像剤としての磁性トナー１０を担持して、矢印Ａ方法に回転することにより、現像スリーブ１４と感光ドラム７とが対向した現像部Ｄに磁性トナー１０を搬送する。現像スリーブ１４内には、磁性トナー１０を現像スリーブ１４上に磁気的に吸引・保持するために、磁石１１が配置されている。磁性トナー１０は現像スリーブ１４との摩擦により、感光ドラム７上の静電潜像を現像可能な摩擦帯電電荷を得る。
【０２４１】
現像部Ｄに搬送される磁性トナー１０の層厚を規制するために、強磁性金属からなる規制ブレード８が、現像スリーブ１４の表面から約２００〜３００μｍのギャップ幅を持って現像スリーブ１４に臨むように、ホッパー９から垂下されている。磁石１１の磁極Ｎ１からの磁力線がブレード８に集中することにより、現像スリーブ１４上に磁性トナー１０の薄層が形成される。ブレード８としては非磁性ブレードを使用することもできる。
【０２４２】
現像スリーブ１４上に形成される磁性トナー１０の薄層の厚みは、現像部Ｄにおける現像スリーブ１４と感光ドラム７との間の最小間隙よりも更に薄いものであることが好ましい。このようなトナー薄層により静電潜像を現像する方式の現像装置、即ち非接触型現像装置に、本発明は特に有効である。しかし、現像部においてトナー層の厚みが現像スリーブ１４と感光ドラム７との間の最小間隙以上の厚みである現像装置、即ち接触型現像装置にも、本発明は適用することができる。
【０２４３】
説明の煩雑を避けるため、以下の説明では、非接触型現像装置を例に採って行う。
【０２４４】
上記現像スリーブ１４には、これに担持された一成分磁性現像剤である磁性トナー１０を飛翔させるために、電源１５により現像バイアス電圧が印加される。この現像バイアス電圧として直流電圧を使用するときは、静電潜像の画像部（磁性トナー１０が付着して可視化される領域）の電位と背景部の電位との間の値の電圧が、現像スリーブ１４に印加されることが好ましい。一方、現像画像の濃度を高め或は階調性を向上するために、現像スリーブ１４に交番バイアス電圧を印加して、現像部Ｄに向きが交互に反転する振動電界を形成してもよい。この場合、上記画像部の電位と背景部の電位の間の値を有する直流電圧成分が重畳された交番バイアス電圧を現像スリーブ１４に印加することが好ましい。
【０２４５】
また、高電位部と低電位部を有する静電潜像の高電位部にトナーを付着させて可視化する、いわゆる正規現像では、静電潜像の極性と逆極性に帯電するトナーを使用し、一方、静電潜像の低電位部にトナーを付着させて可視化する、いわゆる反転現像では、トナーは静電潜像の極性と同極性に帯電するトナーを使用する。尚、高電位と低電位というのは、絶対値による表現である。いずれにしても、磁性トナー１０は現像スリーブ１４との摩擦により静電潜像を現像するための極性に帯電する。
【０２４６】
図４は本発明の他の実施例を示す構成図である。
【０２４７】
図４の現像装置では、現像スリーブ１４上の磁性トナー１０の層厚を規制する部材として、ウレタンゴム，シリコーンゴム等のゴム弾性を有する材料、或はリン青銅，ステンレス鋼等の金属弾性を有する材料などの弾性板１７を使用し、この弾性板１７を現像スリーブ１４に圧接させていることが特徴である。このような現像装置では、現像スリーブ８上に更に薄いトナー層を形成することができる。図４の現像装置のその他の構成は、図３に示した現像装置と基本的に同じで、図４において図３に付した符号と同一の符号は同一の部材を示す。
【０２４８】
上記のようにして現像スリーブ１４上にトナー層を形成する図４に示すような現像装置は、弾性板１７によりトナーを現像スリーブ１４上に擦りつけるため、トナーの摩擦帯電量も多くなり、画像濃度の向上が図られる。また、非磁性一成分トナーにおいては、このような現像装置が用いられる。
【０２４９】
次に本発明で用いた接触帯電・転写方式を有する画像形成方法の一例について、図５の概略構成図を基に説明する。
【０２５０】
８０１は回転ドラム型の感光体であり、図面上時計方向に所定の周速度（プロセススピード）で回転される。８０２は帯電ローラーで、感光体８０１面に押圧力をもって圧接され、感光体８０１の回転に伴い従動回転する。８０３は帯電ローラー８０２に電圧を印加するための帯電バイアス電流Ｖ_２であり、帯電ローラー８０２にバイアスが印加されることで感光体８０１の表面が所定の極性・電位に帯電される。次いで画像露光８０４によって静電荷像が形成され、現像手段８０５によりトナー画像として順次可視化されていく。
【０２５１】
現像手段８０５を構成する現像スリーブには、バイアス印加手段８１３よりバイアスＶ_１が印加される。現像により潜像保持体上に形成されたトナー像は、転写バイアスＶ_３が印加された当接転写手段８０６により転写材８０８に静電転写され、転写材上のトナー像は、加熱加圧手段８１１により加熱加圧定着される。トナー画像転写後の感光体８０１面では転写残りトナー等の付着汚染物質を、感光体８０１にカウンター方向に圧接した弾性クリーニングブレードを具備したクリーニング装置８０９で清浄面化され、更に除電露光装置８１０により除電されて、繰り返して作像される。
【０２５２】
【実施例】
以下、具体的実施例にもって本発明を更に詳しく説明するが、本発明は何らこれらに限定されるものではない。
【０２５３】
（結着樹脂の合成例）
＜樹脂合成例１＞
スチレン ７９．０質量部
ｎ−ブチルアクリレート ２０．０質量部
モノブチルマレート ０．８質量部
２，２’−アゾビス（２，４−ジメチルバレロニトリル） ０．２質量部
【０２５４】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂ａとする。
【０２５５】
樹脂ａ ３０．０質量部
スチレン ５６．０質量部
ｎ−ブチルアクリレート １２．２質量部
モノブチルマレート １．４質量部
ジビニルベンゼン ０．４質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド １．０質量部
【０２５６】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、減圧下で溶媒を蒸留留去した。このようにして得られた樹脂を樹脂Ａとする。この樹脂Ａの酸価は、５．２であった。
【０２５７】
＜樹脂合成例２＞
スチレン ７９．０質量部
ｎ−ブチルアクリレート ２１．０質量部
２，２’−ビス（４，４−ジ−ｔｅｒｔ−ブチル
パーオキシシクロヘキシル）プロパン ０．３質量部
【０２５８】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了した。
【０２５９】
スチレン ８２．０質量部
ｎ−ブチルアクリレート １７．０質量部
モノブチルマレート １．０質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド １．０質量部
【０２６０】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、樹脂成分の質量比が、前者２５後者７５となるように溶液を混合した後、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｂとする。この樹脂Ｂの酸価は、２．３であった。
【０２６１】
＜樹脂合成例３＞
スチレン ７７．０質量部
ｎ−ブチルアクリレート ２０．０質量部
モノブチルマレート ３．０質量部
２，２’−ビス（４，４−ジ−ｔｅｒｔ−ブチル
パーオキシシクロヘキシル）プロパン ０．３質量部
【０２６２】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了した。
【０２６３】
スチレン ７８．０質量部
ｎ−ブチルアクリレート １８．０質量部
メタクリル酸 ４．０質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド １．０質量部
【０２６４】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、樹脂成分の質量比が、前者４後者６となるように溶液を混合した後、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｃとする。この樹脂Ｃの酸価は、１８．８であった。
【０２６５】
＜樹脂合成例４＞
スチレン ７３．７質量部
ブチルアクリレート ２２．０質量部
アクリル酸 ３．５質量部
ジビニルベンゼン ０．８質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド ０．８質量部
【０２６６】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｄとする。この樹脂Ｄの酸価は、２７．０であった。
【０２６７】
＜樹脂合成例５＞
スチレン ７２．７質量部
ブチルアクリレート ２２．０質量部
アクリル酸 ４．５質量部
ジビニルベンゼン ０．８質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド ０．８質量部
【０２６８】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｅとする。この樹脂Ｅの酸価は、３４．８であった。
【０２６９】
＜樹脂比較合成例１＞
スチレン ８０．０質量部
ｎ−ブチルアクリレート ２０．０質量部
２，２’−ビス（４，４−ジ−ｔｅｒｔ−ブチル
パーオキシシクロヘキシル）プロパン ０．３質量部
【０２７０】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了した。
【０２７１】
スチレン ８３．０質量部
ｎ−ブチルアクリレート １７．０質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド １．０質量部
【０２７２】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、樹脂成分の質量比が、前者３後者７となるように溶液を混合した後、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｆとする。この樹脂Ｆの酸価は、０．１であった。
【０２７３】
＜樹脂比較合成例２＞
スチレン ６８．７質量部
ブチルアクリレート ２２．０質量部
メタクリル酸 ８．５質量部
ジビニルベンゼン ０．８質量部
ジ−ｔｅｒｔ−ブチルパーオキサイド ０．８質量部
【０２７４】
上記原料を、加熱したキシレン２００質量部中に４時間かけて滴下した。更に、キシレン還流下で重合を完了し、減圧下で溶媒を蒸留除去した。このようにして得られた樹脂を樹脂Ｇとする。この樹脂Ｇの酸価は、５５．２であった。
【０２７５】
（樹脂層を表面に形成した現像剤担持体の製造例）
＜現像スリーブ製造例１＞
フェノール樹脂中間体 １２５質量部
カーボンブラック ５質量部
結晶性グラファイト ４５質量部
メタノール ４１質量部
イソプロピルアルコール ２８４質量部
フェノール樹脂中間体のメタノール溶液をイソプロピルアルコール（ＩＰＡ）で希釈し、カーボンブラックと結晶性グラファイトを添加し、ガラスビーズを用いたサンドミルにより分散を行った。次にこの塗料を用いてスリーブ上に樹脂層の塗工を行った。
【０２７６】
現像スリーブとしては、外径２０ｍｍ，肉厚０．８ｍｍのステンレス鋼円筒管の表面を研磨加工して、円筒管の振れが１０μｍ以下、表面粗さがＲｚ表記で４μｍ以下にして用いた。このスリーブを垂直に立てて、一定速度で回転させるとともに上下端部にマスキングを施し、スプレーガンを一定速度で下降させながら上記塗料を塗布した。スリーブ両端のマスキング幅は３ｍｍに設定した。これを乾燥炉にて１６０℃で２０分間乾燥硬化させた後、樹脂コートスリーブ表面に、帯状のフェルトを４ｋｇｆの押しあて荷重をもって摺擦させ表面磨き加工を行い、膜厚の均一な樹脂層コートスリーブを得た。
【０２７７】
この樹脂層の膜厚は１０μｍ、表面粗さＲａは６点平均で０．８６μｍ、体積抵抗は４Ω・ｃｍであり、更に鉛筆硬度を測定したところ、２Ｈであった。このスリーブにマグネットを挿入し、両端にフランジを取り付けて現像スリーブ１とした。
【０２７８】
＜現像スリーブ製造例２＞
フェノール樹脂中間体 １２５質量部
カーボンブラック ５質量部
結晶性グラファイト ４５質量部
表面処理シリカ微粉末 ２５質量部
（ＢＥＴによる比表面積が約１３０ｍ^２／ｇの乾式シリカ微粉末に、メチルトリメトキシシランにより表面処理を行なったもの）
メタノール ５８質量部
イソプロピルアルコール ４０８質量部
上記材料を、サンドミルを用いて分散した。フェノール樹脂中間体のメタノール溶液をイソプロピルアルコール（ＩＰＡ）の一部で希釈し、カーボンブラックと結晶性グラファイトを添加し、ガラスビーズを用いたサンドミルにより分散を行った。ここに更に残りのＩＰＡ中に分散した上記処理シリカを充填剤として添加し、更にサンドミル分散を進めた。
【０２７９】
次にこの塗料を用いて、樹脂コート現像スリーブ製造例１と同様にしてスリーブ上に樹脂層の塗工を行った後に表面磨き加工を行った。この導電性樹脂層の膜厚は１５μｍ、表面粗さＲａは６点平均で１．０８μｍ、体積抵抗は７Ω・ｃｍであり、更に鉛筆硬度を測定したところ、３Ｈであった。このスリーブにマグネットを挿入し、両端にフランジを取り付けて現像スリーブ２とした。
【０２８０】
＜現像スリーブ製造例３＞
現像スリーブ製造例１で使用した塗料を用い、現像スリーブとしては、外径１２ｍｍ，肉厚０．８ｍｍのアルミニウム円筒管の表面を研磨加工して、円筒管の振れが１０μｍ以下、表面粗さがＲｚ表記で４μｍ以下にして用いた。このスリーブを垂直に立てて、一定速度で回転させるとともに上下端部にマスキングを施し、スプレーガンを一定速度で下降させながら上記塗料を塗布した。スリーブ両端のマスキング幅は３ｍｍに設定した。これを乾燥炉にて１６０℃で２０分間乾燥硬化させた後、樹脂コートスリーブ表面に、帯状のフェルトを４ｋｇｆの押しあて荷重をもって摺擦させ表面磨き加工を行い、膜厚の均一な樹脂層コートスリーブを得た。
【０２８１】
この樹脂層の膜厚は１１μｍ、表面粗さＲａは６点平均で０．９７μｍ、体積抵抗は４Ω・ｃｍであり、更に鉛筆硬度を測定したところ、２Ｈであった。このスリーブの両端にフランジを取り付けて現像スリーブ４とした。
【０２８２】
＜現像スリーブ比較製造例１＞
現像スリーブとしては、外径２０ｍｍ，肉厚０．８ｍｍのステンレス鋼円筒管の表面を研磨加工して、円筒管の振れが１０μｍ以下、表面粗さがＲｚ表記で４μｍ以下にしたものを、上下端部にマスキングを施し、不定形アルミナ砥粒（＃３００）を用いブラストマシンにより、３．９２×１０^−２ＭＰａ（４．０ｋｇｆ／ｃｍ）のブラスト圧でブラスト処理を行った。スリーブ両端のマスキング幅は３ｍｍに設定した。このブラスト処理スリーブの表面粗さＲａは６点平均で１．１２μｍであった。このスリーブにマグネットを挿入し、両端にフランジを取り付けて現像スリーブ３とした。
【０２８３】
［実施例１］
・結着樹脂Ａ １００質量部
・マグネタイト ９０質量部
（八面体、平均粒子径０．２２μｍ、ＢＥＴ＝７．９ｍ^２／ｇ、
ケイ素含有量０．３５ｗｔ％、σｓ＝８４．５Ａｍ^２／ｋｇ、
σｒ＝１０．９Ａｍ^２／ｋｇ）
・低分子量ポリプロピレンワックス（融点１３０℃） ４質量部
・イミダゾール誘導体の化合物例（８） ２質量部
【０２８４】
上記材料をヘンシェルミキサーで良く前混合した後、１４０℃に設定した二軸混練押出し機によって溶融混練した。得られた混練物を冷却し、カッターミルで粗粉砕した後、ジェット気流を用いた微粉砕機を用いて微粉砕し、得られた微粉砕物を更に風力分級機で分級し、重量平均粒径８．５μｍの分級微粉体を得た。
【０２８５】
得られた分級微粉体１００質量部に、乾式法で製造されたシリカ微粉体（ＢＥＴ比表面積２００ｍ^２／ｇ）１００質量部当りアミノ変性シリコーンオイル（アミン当量８３０，２５℃における粘度７０ｃＳｔ）１７質量部で処理した疎水性シリカ０．８質量部を加え、ヘンシェルミキサーで混合し、目開き１５０μｍのメッシュで篩い、正帯電性一成分磁性トナー１を得た。
【０２８６】
得られたトナー１について、次に示す各評価試験を行なった。
【０２８７】
耐オフセット性評価試験：
市販の複写機ＮＰ６０３０（キヤノン（株）社製）の定着器を外部へ取り外し、複写機外でも動作し、定着ローラー温度を任意に設定可能にし、プロセススピードを１００ｍｍ／ｓｅｃとなるように改造した外部定着器を用い、未定着画像を通紙することにより耐オフセット性を評価した。評価に際して、定着ローラーの温度を２３０℃に設定し、オフセットの様子を観察し、下に示すランクに分類した（評価環境：常温／常湿（２３℃／６０％ＲＨ））。
【０２８８】
オフセットランク
◎（優） 全くオフセットが見られない。
○（良） 極わずかオフセットが見られる。
×（不可） オフセットが発生する。
【０２８９】
スリーブコート性評価試験：
スリーブ上のトナーコートを目視し、ブロッチの発生レベルを下に示すランクに分類した（評価環境：常温／常湿（２３℃／６０％ＲＨ）、常温／低湿（２３℃／５％ＲＨ）、高温／高湿（３２．５℃／８０％ＲＨ））。
【０２９０】
ブロッチランク
◎（優） 全く発生していない。
○（良） スリーブ端部にわずか発生している。
△（可） 極わずか発生しているが画像には影響しない。
×（不可） はっきりと発生しており画像に影響する。
【０２９１】
画像評価試験：
市販の複写機ＮＰ６０３０（キヤノン（株）社製）を用い、現像スリーブを本発明の現像スリーブ製造例１に示した現像スリーブ１に交換し、常温／常湿環境下において１００００枚複写し、常温／低湿環境、及び高温／高湿環境の各環境下においてそれぞれ１００００枚複写を行い、画像濃度、カブリを評価した（評価環境：常温／常湿（２３℃／６０％ＲＨ）、常温／低湿（２３℃／５％ＲＨ）、高温／高湿（３２．５℃／８０％ＲＨ））。
【０２９２】
また、常温／常湿環境下にて１００００枚複写した後の現像スリーブ表面の一部をエタノールで洗浄に拭き取り、ベタ黒画像をプリントし、エタノール拭き清掃前後の画像濃度を測定し、その差を算出することによりスリーブ汚染の評価を行ない、その濃度差が小さいものほど汚染抑制が良い。
【０２９３】
画像濃度は、「マクベス反射濃度計」（マクベス社製）を用いて測定した。カブリは、「反射濃度計」（東京電色技術センター社製）を用いて、転写紙の反射濃度と、ベタ白をコピーした後の転写紙の反射濃度とを測定し、その差分をカブリ値とし、数値の小さいものほどカブリ抑制が良い。
【０２９４】
これらの耐オフセット性試験、スリーブコート性試験、画像評価試験の評価結果を表１及び２にまとめた。
【０２９５】
［実施例２］
実施例１において、結着樹脂Ａを結着樹脂Ｂに変更する以外は実施例１と同様にして、分級微粉体並びにトナー２を得た。このトナー２について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０２９６】
［実施例３］
実施例１において、結着樹脂Ａを結着樹脂Ｃに変更する以外は実施例１と同様にして、分級微粉体並びにトナー３を得た。このトナー３について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０２９７】
［実施例４］
実施例１において、結着樹脂Ａを結着樹脂Ｄに変更する以外は実施例１と同様にして、分級微粉体並びにトナー４を得た。このトナー４について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０２９８】
［実施例５］
実施例１において、結着樹脂Ａを結着樹脂Ｅに変更する以外は実施例１と同様にして、分級微粉体並びにトナー５を得た。このトナー５について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０２９９】
［比較例１］
実施例１において、結着樹脂Ａを結着樹脂Ｆに変更する以外は実施例１と同様にして、分級微粉体並びにトナー６を得た。このトナー６について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３００】
［比較例２］
実施例１において、結着樹脂Ａを結着樹脂Ｇに変更する以外は実施例１と同様にして、分級微粉体並びにトナー７を得た。このトナー７について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０１】
［実施例６］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（１）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー８を得た。このトナー８について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０２】
［実施例７］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（３）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー９を得た。このトナー９について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０３】
［実施例８］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（４）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー１０を得た。このトナー１０について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０４】
［実施例９］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（１０）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー１１を得た。このトナー１１について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０５】
［実施例１０］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（１１）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー１２を得た。このトナー１２について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０６】
［実施例１１］
実施例１において、イミダゾール誘導体の化合物例（８）を化合物例（１４）に変更する以外は実施例１と同様にして、分級微粉体並びにトナー１３を得た。このトナー１３について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０７】
［比較例３］
実施例１において、イミダゾール誘導体の化合物例（８）をニグロシン染料に変更する以外は実施例１と同様にして、分級微粉体並びにトナー１４を得た。このトナー１４について、実施例１と同様に各評価を行った。評価結果を表１及び２にまとめた。
【０３０８】
［実施例１２］
実施例１において、現像スリーブ１を現像スリーブ２に変更する以外は実施例１と同様にして耐オフセット性試験以外の各評価を行った。評価結果を表１及び２にまとめた。
【０３０９】
［比較例４］
実施例１において、現像スリーブ１を現像スリーブ３に変更する以外は実施例１と同様にして耐オフセット性試験以外の各評価を行った。評価結果を表１及び２にまとめた。
【０３１０】
【表１】

【０３１１】
【表２】

【０３１２】
［実施例１３］
・結着樹脂Ａ １００質量部
・銅フタロシアニン ３．５質量部
・低分子量ポリプロピレンワックス（融点１３０℃） ３質量部
・イミダゾール誘導体の化合物例（１８） ２質量部
【０３１３】
上記材料をヘンシェルミキサーで良く前混合した後、１２０℃に設定した二軸混練押出し機によって溶融混練した。得られた混練物を冷却し、カッターミルで粗粉砕した後、ジェット気流を用いた微粉砕機を用いて微粉砕し、得られた微粉砕物を更に風力分級機で分級し、重量平均粒径９．１μｍの分級微粉体を得た。
【０３１４】
得られた分級微粉体１００質量部に、乾式法で製造されたシリカ微粉体（ＢＥＴ比表面積２００ｍ^２／ｇ）１００質量部当りアミノ変性シリコーンオイル（アミン当量８３０，２５℃における粘度７０ｃＳｔ）１７質量部で処理した疎水性シリカ０．８質量部を加え、ヘンシェルミキサーで混合し、目開き１５０μｍのメッシュで篩い正帯電性非磁性一成分トナーを得た。
【０３１５】
市販の複写機ＦＣ−３３０（キヤノン（株）社製）を用い、現像スリーブを本発明の現像スリーブ４に交換し、常温／常湿環境下において１０００枚複写し、常温／低湿環境及び高温／高湿環境の各環境下においてそれぞれ１０００枚複写を行い、実施例１と同様に画像濃度、カブリを評価した（評価環境：常温／常湿（２３℃／６０％ＲＨ）、常温／低湿（２３℃／５％ＲＨ）、高温／高湿（３２．５℃／８０％ＲＨ））。
【０３１６】
また、常温／常湿環境下にて１０００枚複写した後の現像スリーブ表面の一部をエタノールで清浄に拭き取り、実施例１と同様にスリーブ汚染の評価を行なった。
【０３１７】
その結果、各環境で、画像濃度は１．２０〜１．３０、カブリは０．３〜０．８で鮮明な青色画像が得られた。スリーブ汚染もΔ０．０２未満で問題がなく、オフセットも発生しなかった。
【０３１８】
【発明の効果】
本発明の画像形成方法によれば、酸価を有するポジトナーにおいて、本発明に示した特定のイミダゾール誘導体を荷電制御剤として用いることにより、トナーの帯電特性及び現像特性を損なうことなく耐オフセット性を飛躍的に向上させることができ、且つ、現像剤担持体として金属基体上に樹脂層を形成したものを用いることにより、帯電付与能力が大幅に改善され現像特性を向上させることができ、長期にわたり画像濃度低下やカブリ等の無い高精細画像を安定して提供することができる。
【図面の簡単な説明】
【図１】本発明の現像剤担持体の一部分の断面の概略図である。
【図２】本発明の現像剤担持体の一部分の断面（（Ａ）は磨き加工前、（Ｂ）は磨き加工後）の概略図である。
【図３】本発明の現像剤担持体が組み込まれる磁性現像剤補給系現像装置の一例（規制部材に磁性ブレードを使用）を示す概略図である。
【図４】本発明の現像剤担持体が組み込まれる磁性現像剤補給系現像装置の他の例（規制部材に弾性ブレードを使用）を示す概略図である。
【図５】本発明の画像形成方法を説明するための概略図である。
【符号の説明】
１ 被膜層（樹脂層）
２ 導電性物質
３ 充填剤
４ 結着樹脂
５ 固体潤滑剤
６ 円筒状基体
７ 感光ドラム（潜像保持体）
８ 規制ブレード
９ ホッパー
１０ トナー
１１ 磁石
１２ 円筒状基体
１３ 被膜層（樹脂層）
１４ 現像スリーブ（現像剤担持体）
１５ 電源
１７ 弾性ブレード
Ａ 現像スリーブの回転方向
Ｂ 感光ドラムの回転方向
Ｄ 現像部
５０１ 被膜層（樹脂層）
５０２ 固体潤滑剤
５０３ 導電性物質
５０４ 充填剤
５０５ 結着樹脂
５０６ 円筒状基体
８０１ 潜像保持体
８０１ａ 光導電層
８０１ｂ 導電性基層
８０２ 帯電ローラー
８０２ａ 導電性弾性層
８０２ｂ 芯金
８０３ 帯電バイアス電源
８０４ 画像露光
８０５ 現像ローラー
８０６ 転写ローラー
８０６ａ 導電性弾性層
８０６ｂ 芯金
８０７ 転写バイアス電源
８０８ 転写材
８０９ クリーニング装置
８１０ 除電露光装置
８１１ 加熱加圧手段
８１３ 現像バイアス電源[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming method including a step of developing an electrostatic image formed in electrophotography, electrostatic recording, and magnetic recording using toner.
[0002]
[Prior art]
Conventionally, many electrophotographic methods are known as described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748. However, generally, using a photoconductive substance, an electric latent image (electrostatic latent image) is formed on the photoreceptor by various means, and then the latent image is developed using toner, and if necessary, developed. After transferring the toner image to a transfer material such as paper, the toner image is fixed by heating, pressure, heating and pressurizing, or solvent vapor to obtain a copy, and the toner remaining on the photoreceptor without being transferred is various. It is cleaned by the method and the above steps are repeated.
[0003]
In recent years, such copying apparatuses have been strictly pursued to be smaller, lighter, faster, and more reliable, reflecting the changing market needs such as compounding and personalization. As a result, the performance required of the toner is becoming more sophisticated.
[0004]
For example, various methods and apparatuses have been proposed and developed for the process of fixing a toner image on a transfer sheet such as paper, but the most common method at present is a heat compression method using a heat roller. In the heat pressure bonding method using a heat roller, fixing is performed by allowing a toner image of a sheet to be fixed to pass through the surface of the heat roller having a surface formed of a material having releasability with respect to toner while contacting the sheet under pressure. In this method, since the surface of the heat roller and the toner image of the sheet to be fixed come into contact with each other under pressure, the heat efficiency when fixing the toner image on the sheet to be fixed is extremely good, and the fixing can be performed quickly. it can.
[0005]
However, the above-described heat roller fixing method that has been frequently used in the related art is based on a so-called offset, which is a fixing failure due to a change in the temperature of the heat roller due to the passage of a transfer material or other external factors, and a transfer of toner to the heat roller. In order to prevent the phenomenon, it is necessary to maintain the heating roller in the optimal temperature range, and for this purpose, the heat capacity of the heating roller or the heating element must be increased, which requires large electric power and This results in an increase in the size of the image forming apparatus and an increase in the temperature inside the apparatus.
[0006]
Therefore, various means have been conventionally proposed for the purpose of preventing toner from adhering to the surface of the fixing roller or improving low-temperature fixability. For example, the surface of the roller is formed of a material with excellent releasability from toner, such as silicone rubber or fluororesin, and the releasability such as silicone oil is used to prevent offset and prevent the roller surface from fatigue. The roller surface is coated with a thin film of a good liquid. However, although this method is extremely effective in preventing toner offset, it requires a device for supplying an anti-offset liquid, which also complicates the fixing device and increases the size of the device. have.
[0007]
Therefore, in order to realize an efficient fixing method while achieving good fixability of a toner-toned image to a transfer material, prevention of offset, and the like, the characteristics of the toner are imposed in addition to the fixing device described above. However, it becomes very large.
[0008]
In other words, in particular, from the viewpoint of the offset prevention technology, an anti-offset method by supplying an anti-offset liquid is not preferable. Rather, there is a strong demand for development of a toner having a wide fixing temperature range and high anti-offset property. . Therefore, in order to increase the releasability of the toner itself, a method of adding a wax such as a low-molecular-weight polyethylene or a low-molecular-weight polypropylene that sufficiently melts when heated has been performed. , And the charging characteristics become unstable, which tends to cause a decrease in developability during durability. Therefore, various attempts have been made to improve the binder resin as other methods.
[0009]
For example, a method of increasing the glass transition temperature (Tg) and the molecular weight of the binder resin in the toner in order to prevent the offset and improving the melt viscoelasticity of the toner is also known. However, when the offset phenomenon is improved by such a method, the developing property does not significantly affect but the fixing property becomes insufficient, and the fixing property at a low temperature required for high-speed development and energy saving, that is, There is a problem that the low-temperature fixability is poor.
[0010]
In order to improve the low-temperature fixability of the toner, it is necessary to reduce the viscosity of the toner at the time of melting and increase the contact area with the fixing member. For this purpose, it is necessary to reduce the Tg and the molecular weight of the binder resin used. Is done.
[0011]
That is, since low-temperature fixability and anti-offset property are contradictory, it is very difficult to develop a toner that simultaneously satisfies these functions.
[0012]
In order to solve this problem, for example, Japanese Patent Publication No. 51-23354 discloses a toner comprising a suitably crosslinked vinyl polymer by adding a crosslinking agent and a molecular weight modifier, and further discloses a vinyl polymer. On the other hand, a large number of blend-type toners combining Tg, molecular weight and gel content have been proposed.
[0013]
A toner containing such a crosslinked vinyl polymer or gel component shows an excellent effect in offset resistance. However, if the crosslinked vinyl polymer is used as a raw material for the toner when these are contained, the internal friction in the polymer becomes extremely large in the melt-kneading step in the production of the toner, and a large shear force is applied. It takes unity. For this reason, in many cases, the molecular chains are cut, resulting in a decrease in the melt viscosity and adversely affecting the offset resistance.
[0014]
In order to solve this problem, JP-A-55-90509, JP-A-57-178249, JP-A-57-178250 and JP-A-60-4946 disclose a resin having a carboxylic acid and a metal compound as a toner. It is introduced that it is used as a raw material, heat-reacts at the time of melt-kneading, forms a crosslinked polymer, and contains it in the toner.
[0015]
JP-A-61-110155 discloses that a binder having a vinyl resin monomer and a more specific monoester compound as essential constitutional units is reacted with a polyvalent metal compound and crosslinked via a metal. And JP-A-61-110156.
[0016]
Further, JP-A-63-214760, JP-A-63-217362, JP-A-63-217363 and JP-A-63-217364 have a molecular weight distribution divided into two groups, a low molecular weight and a high molecular weight. It is disclosed that a carboxylic acid group contained on the molecular weight side reacts with a polyvalent metal ion to form a crosslink (a dispersion of a metal compound is added to a solution obtained by solution polymerization, and the mixture is heated and reacted). I have.
[0017]
Further, JP-A-2-168264, JP-A-2-23569, JP-A-5-173363, JP-A-5-173366, and JP-A-5-241371 disclose a low molecular weight component and a high molecular weight in a binder resin. There have been proposed toner binder compositions and toners in which the molecular weight of the components, the mixing ratio, the acid value and the ratio thereof are controlled to improve the fixing property, the anti-offset property and the like.
[0018]
JP-A-62-9256 discloses a binder composition for a toner in which two types of vinyl resins having different molecular weights and resin acid values are blended.
[0019]
Although these proposals described above have advantages and disadvantages in terms of improving the anti-offset property, it is true that excellent effects can be obtained. However, since these introduce an acid value into the toner binder, they impart a negative charge to the toner although there are some differences. As a result, when applied to a positive toner, the charging characteristics at the time of startup and durability of the toner, or in a high or low humidity environment are significantly impaired, and the development characteristics such as image density and fog are lowered. Further, the toner cannot be stably maintained at an appropriate charge amount, causing an increase in toner cohesiveness and the like, so that satisfactory results have not been obtained.
[0020]
On the other hand, the toner needs to have a positive or negative charge according to the charge polarity of the electrostatic latent image to be developed, and therefore, it is generally known to add a dye, a pigment or a charge control agent. . Among these, as the positive charge control agent, quaternary ammonium salts and their lake pigments, polymers having tertiary amino groups or quaternary ammonium salts in the side chains, triphenylmethane dyes and these lake pigments, nigrosine and fatty acids Modified products such as metal salts are known.
[0021]
However, with these conventional positive charge control agents, a sufficient amount of charge cannot be given to the toner, or even if a sufficient amount of charge is given, the toner is affected by other toner constituent materials, and excessive toner frictional charge or Nonuniform electrification caused blotches and increased toner cohesiveness, and also tended to cause deterioration in development characteristics such as image density reduction and fog. This tendency is particularly remarkable in a positive toner having an acid value. Further, there is a problem of sleeve contamination which occurs when the charge control agent is missing from the toner and adheres to the surface of the sleeve as the developer carrier.
[0022]
On the other hand, when the toner is brought into contact with a sleeve as a developer carrying member and frictionally charged, there is a problem of how to stably and efficiently maintain proper charging for a long time.
[0023]
As a sleeve in an image forming apparatus using electrophotography, for example, a metal, an alloy thereof, or a compound thereof is formed into a cylindrical shape, and the surface is treated by electrolysis, blasting, sanding, or the like so as to have a predetermined surface roughness. Is used. As general sleeve base materials, stainless steel, aluminum, and nickel proposed in Japanese Patent Application Laid-Open No. 57-66455 are widely used.
[0024]
However, it is difficult to adjust the charge amount of the toner when the positive toner is applied by using these sleeves. For example, when stainless steel is used as the sleeve base material, the charging ability is strong, so The toner present in the vicinity will have a very high charge, and will be strongly attracted to the sleeve surface by the mirroring force, forming an immobile layer. As a result, the chance of friction between the toner and the sleeve is reduced, and suitable charging is inhibited. As a result, blotching due to non-uniform charging or excessive charging of the toner is likely to occur, and the developing characteristics naturally deteriorate.
[0025]
Further, when aluminum is used as the sleeve base material, the ability to impart a charge to the positive toner is high, but due to the softness of the material, the durability is poor, and image deterioration due to surface wear is likely to occur. In order to provide wear resistance, there is a technique of coating or plating metal on the surface of the aluminum substrate.However, the durability is improved by improving the hardness of the sleeve surface, but on the other hand, the positive toner is charged compared to stainless steel etc. In many cases, the toner had low ability, and was likely to cause poor charging of the toner.
[0026]
Similarly, for the case in which the resin layer is provided on the surface of the sleeve base material, the durability is good, but the control of the charging property to the toner is restricted, and the application range is wide for negative charging, but When applied to the application of positive charge, it is not possible to impart appropriate charge-imparting ability, and in particular, when the binder resin has an acid value, it is presently difficult to apply the charge. .
[0027]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming method that solves the above-mentioned problems. That is, the object of the present invention is to provide a uniform toner coat layer having excellent anti-offset properties and no blotch on the developer carrier, and to obtain a stable and high image density and low fog with high durability. An object of the present invention is to provide an image forming method capable of obtaining good image characteristics stably for a long period of time.
[0028]
[Means for Solving the Problems]
The present invention conveys a positively chargeable toner containing at least a binder resin for a toner, a colorant and a charge control agent by a developer carrying member having a resin layer formed on a metal substrate, and carries the toner on the electrostatic latent image holding member. In the image forming method for forming the toner image by transferring the positively chargeable toner from the developer carrier to the electrostatic latent image formed on the developer and developing the toner,
The acid value of the entire polymer component of the binder resin for toner is 0.5 mgKOH / g or more and 50 mgKOH / g or less;
The charge control agent is an imidazole derivative compound, wherein the imidazole derivative compound has a condensate of imidazole or a derivative thereof and an aldehyde, and the condensate is a cyclic condensate or a cyclic condensate and a chain condensate. The above object is attained by an image forming method characterized by being a mixture of the above.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
The inventor has set the acid value of the entire polymer component of the binder resin for toner at 0.5 mgKOH / g or more and 50 mgKOH / g or less, and by using a specific imidazole derivative compound described later as a charge control agent, the positive toner It has been found that good offset resistance can be realized without impairing the charging characteristics and powder characteristics as a material. Further, by using a developing sleeve for forming a resin layer on a metal substrate as a developing sleeve for frictionally charging the toner, excellent charging characteristics which have not been obtained in the past can be obtained. , And as a result, it became clear that excellent development characteristics could be maintained.
[0030]
The reason for achieving the effect in the present invention will be described below.
[0031]
In the toner having an acid value, in a toner containing an imidazole derivative compound as a charge control agent, the imidazole derivative compound is a condensate of imidazole or a derivative thereof and an aldehyde, and the condensate is a cyclic condensate or a cyclic condensate. When a mixture of chain condensates is used, it is excellent in quick and uniform triboelectric charging characteristics, has sufficient triboelectric charging ability even in a positive toner introduced with an acid value, and suppresses excessive charging while having a high charge amount. It was found to have excellent characteristics. The mechanism by which excessive charging of the toner is suppressed has not been elucidated at the present time, but this is because some interaction has occurred between the acid resin and the imidazole derivative compound. By suppressing the excessive charging of the toner, it is possible to prevent the occurrence of blotches and the increase in toner cohesion.
[0032]
The toner containing the imidazole derivative compound used in the present invention has a small variation in charging characteristics even under a high or low humidity environment, can maintain stable development characteristics, and at the same time, when the acid resin is used, the imidazole derivative from the toner can be obtained. Since there is little loss of the compound, the occurrence of sleeve contamination can be suppressed.
[0033]
Further, the toner used in the present invention has a resin layer on a metal substrate in a frictional charging process with a developer carrier, rather than using a general stainless steel, aluminum, or metal plating as a material of the developer carrier. It has been clarified that the use of the developing sleeve on which the toner is formed exhibits much more excellent charging ability.
[0034]
This is due to the difference in chargeability between the toner and the material of each developer carrying member. That is, regarding the toner containing the binder resin having an acid value and the condensate of the imidazole derivative, the chargeability with the material of the developer carrier is considered to be the amount of charge generated by contact with stainless steel, aluminum, metal plating, or the like. In comparison, it was found that a larger amount of charge was generated when contacting a metal substrate having a resin layer (for example, a carbon black-dispersed resin layer).
[0035]
It is known that a toner containing a conventionally known general positively chargeable charge control agent, for example, nigrosine, exhibits good positively chargeable properties when it comes into contact with stainless steel. When this toner is brought into contact with a developer carrier having a resin layer (for example, a carbon black-dispersed resin layer) as a surface layer, the positive charging property is slightly lowered, and when the binder resin has an acid value, the charging performance is reduced. Drops. Further, other positively chargeable charge control agents have the same tendency.
[0036]
The acid value of the entire polymer component of the binder resin for toner used in the present invention is 0.5 mgKOH / g to 50 mgKOH / g, preferably 0.5 mgKOH / g to 30 mgKOH / g, and more preferably. Is preferably 0.5 mgKOH / g or more and 20 mgKOH / g or less. When the acid value of the entire polymer component is less than 0.5 mgKOH / g, no offset prevention effect, no development stability due to interaction with the imidazole derivative and no sleeve contamination prevention effect are exhibited, while if it exceeds 50 mgKOH / g, There is a tendency that the negative chargeability of the binder resin for toner is increased, the image density is reduced, and fog is increased.
[0037]
In the present invention, the acid value (JIS acid value) of the entire polymer component of the binder resin for toner is determined by the following method.
[0038]
<Measurement of acid value>
The basic operation conforms to JIS K-0070.
1) The sample is used after removing additives other than the polymer component in advance, or the acid value and content of the component other than the polymer are obtained in advance. 0.5 to 2.0 (g) of the crushed sample is precisely weighed, and the weight of the polymer component is defined as W (g).
2) The sample is placed in a 300 (ml) beaker, and 150 (ml) of a mixed solution of toluene / ethanol (4/1) is added and dissolved.
3) Titration using a 0.1N KOH ethanol solution using a potentiometric titrator (for example, a potentiometric titrator AT-400 manufactured by Kyoto Electronics Co., Ltd.)
(Win work station) and automatic titration with ABP-410 motorized burette is available).
4) The amount of the KOH solution used at this time is defined as S (ml), a blank is measured at the same time, and the amount of the KOH solution used at this time is defined as B (ml).
5) Calculate the acid value by the following equation. f is a factor of KOH.
[0039]
Acid value (mgKOH / g) = {(S−B) × f × 5.61} / W
[0040]
Examples of the monomer for adjusting the acid value of the polymer component of the present invention include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid, vinyl acetic acid, isocrotonic acid, acrylic acid such as angelic acid and the like. α- or β-alkyl derivatives, fumaric acid, maleic acid, citraconic acid, alkenyl succinic acid, itaconic acid, mesaconic acid, dimethyl maleic acid, unsaturated dicarboxylic acids such as dimethyl fumaric acid and monoester derivatives or anhydrides thereof Yes, such a monomer can be used alone or as a mixture and copolymerized with another monomer to produce a desired polymer. Among them, it is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid for controlling the acid value.
[0041]
More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monoethyl fumarate, monobutyl fumarate Monoesters of α, β-unsaturated dicarboxylic acids such as monobutyl n-butenylsuccinate, monomethyl n-octenylsuccinate, monoethyl n-butenylmalonate, monomethyl n-dodecenylglutarate, monobutyl n-butenyladipate And alkenyl dicarboxylic acid monoesters.
[0042]
The carboxyl group-containing monomer described above may be added in an amount of 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, based on 100 parts by mass of all the monomers constituting the binder resin.
[0043]
The reason why the monoester monomer of dicarboxylic acid is selected as described above is that it is preferably used in the form of an ester having a low solubility in an aqueous suspension and a high solubility in an organic solvent or another monomer. Because.
[0044]
In the present invention, the carboxylic acid groups and carboxylic acid ester sites in the copolymer obtained by the above method can be saponified by performing an alkali treatment. That is, the carboxylic acid group or carboxylic acid ester site may be changed to a polar functional group by reacting with a cationic component of alkali.
[0045]
This alkali treatment may be carried out after the production of the binder resin, by throwing it into the solvent used during the polymerization as an aqueous solution and stirring the solution. Examples of the alkali that can be used in the present invention include hydroxides of alkali metals and alkaline earth metals such as Na, K, Ca, Li, Mg and Ba; and hydroxides of transition metals such as Zn, Ag, Pb and Ni. Compounds: hydroxides of quaternary ammonium salts such as ammonium salts, alkylammonium salts, and pyridium salts. Particularly preferred examples include NaOH and KOH.
[0046]
In the present invention, the saponification reaction does not need to be performed over all of the carboxylic acid groups and carboxylic acid ester sites in the copolymer, and the saponification reaction partially proceeds and is converted into a polar functional group. Just fine.
[0047]
Further, the amount of the alkali used in the saponification reaction is difficult to determine unconditionally depending on the type of the polar group in the binder resin, the dispersion method, the type of the constituent monomers, and the like. Any double equivalent is acceptable. If it exceeds 5 equivalents, the functional group such as a carboxylic acid ester site is adversely affected by hydrolysis of the ester, formation of a salt by a saponification reaction, and the like.
[0048]
In addition, when the alkali treatment of 0.02 to 5 times equivalent of the acid value is performed, the residual cation concentration after the treatment is included in the range of 5 to 1000 ppm, which can be preferably used to regulate the amount of the alkali. .
[0049]
The resin composition according to the present invention has a glass transition temperature (Tg) of 45 to 80 ° C, preferably 50 to 70 ° C from the viewpoint of storage stability. It causes deterioration and offset during fixing. If the Tg exceeds 80 ° C., the fixability tends to decrease.
[0050]
As a polymerization method that can be used in the present invention as a method for synthesizing the high molecular weight polymer of the resin composition according to the present invention, there are a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.
[0051]
Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase with an emulsifier, and polymerization is carried out using a water-soluble polymerization initiator. In this method, it is easy to control the heat of reaction, and since the phase in which the polymerization is carried out (the oil phase composed of the polymer and the monomer) and the aqueous phase are separate, the termination reaction rate is small, and as a result, the polymerization rate is large. And a high degree of polymerization can be obtained. Further, the reason is that the polymerization process is relatively simple, and that the polymerization product is fine particles, so that it is easy to mix with a colorant, a charge control agent, and other additives in the production of the toner. Therefore, there is an advantage as a method for producing a binder resin for a toner.
[0052]
However, the resulting polymer tends to be impure due to the added emulsifier, and an operation such as salting out is required to remove the polymer. To avoid this inconvenience, suspension polymerization is convenient.
[0053]
In the suspension polymerization, the polymerization is preferably carried out at 100 parts by mass or less (preferably 10 to 90 parts by mass) with respect to 100 parts by mass of the aqueous solvent. Examples of usable dispersants include polyvinyl alcohol, partially saponified polyvinyl alcohol, and calcium phosphate, and are generally used in an amount of 0.05 to 1 part by mass based on 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably from 50 to 95 ° C., but is appropriately selected depending on the initiator used and the intended polymer.
[0054]
The high molecular weight polymer of the resin composition used in the present invention is formed by using a polyfunctional polymerization initiator alone or in combination with a monofunctional polymerization initiator as exemplified below in order to achieve the object of the present invention. Is preferred.
[0055]
Specific examples of the polyfunctional polymerization initiator having a polyfunctional structure include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxy). Isopropyl) benzene, 2,5-dimethyl-2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, tris- (t-butyl) Peroxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid-n-butyl ester , Di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2-bis- ( 2,4-di-t-butylperoxycyclohexyl) propane, 2,2-t-butylperoxyoctane, various polymer oxides, and other functional groups having a polymerization initiation function such as two or more peroxide groups in one molecule. And a peroxide group in one molecule such as diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate. For example, a polyfunctional polymerization initiator having both a functional group having a polymerization initiation function and a polymerizable unsaturated group is selected.
[0056]
Of these, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, di-t-butylperoxy. Hexahydroterephthalate, di-t-butylperoxyazelate and 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane, and t-butylperoxyallyl carbonate.
[0057]
These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to satisfy various performances required as a binder for a toner. In particular, it is preferable to use the polyfunctional polymerization initiator together with a polymerization initiator having a half life of 10 hours lower than the decomposition temperature for obtaining a half life of 10 hours.
[0058]
Specifically, benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, Organic peroxides such as milperoxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide, azobisisobutyronitrile, diazoamino Examples include azo and diazo compounds such as azobenzene.
[0059]
These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator.However, in order to maintain the efficiency of the polyfunctional polymerization initiator properly, the monofunctional polymerization initiator is added in the polymerization step. It is preferably added after the half-life indicated by the polyfunctional polymerization initiator has elapsed.
[0060]
These initiators are preferably used in an amount of 0.05 to 2 parts by mass based on 100 parts by mass of the monomer from the viewpoint of efficiency.
[0061]
In order to achieve the object of the present invention, the high molecular weight polymer is preferably crosslinked with a crosslinkable monomer as exemplified below.
[0062]
As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used. Specific examples include aromatic divinyl compounds (eg, divinylbenzene, divinylnaphthalene, etc.); diacrylate compounds linked by an alkyl chain (eg, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4 -Butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and methacrylates instead of the acrylates of the above compounds); alkyl chains containing an ether bond Compounds such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, Ethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and the above compounds obtained by replacing acrylate with methacrylate); diacrylate compounds linked by a chain containing an aromatic group and an ether bond (for example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and acrylates of the above compounds are methacrylated And polyester-type diacrylate compounds (for example, MANDA (Nippon Kayaku)). As multifunctional crosslinking agents, pentaerythritol acrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and acrylates of the above compounds into methacrylate Alternatives; triallyl cyanurate, triallyl trimellitate; and the like.
[0063]
It is preferable to use these crosslinking agents in an amount of 1 part by mass or less, preferably 0.001 to 0.05 part by mass, based on 100 parts by mass of the other monomer components.
[0064]
Among these crosslinkable monomers, those which are preferably used from the viewpoints of toner fixability and offset resistance include aromatic divinyl compounds (particularly divinylbenzene), divinyl compounds linked by a chain containing an aromatic group and an ether bond. Acrylate compounds are mentioned.
[0065]
On the other hand, as a method for synthesizing the low molecular weight polymer component of the binder resin according to the present invention, a known method can be used. However, in the bulk polymerization method, a polymer having a low molecular weight can be obtained by polymerizing at a high temperature to increase the termination reaction rate, but there is a problem that the reaction is difficult to control. In that regard, in the solution polymerization method, a low molecular weight polymer can be easily obtained under mild conditions by utilizing the difference in the chain transfer of radicals depending on the solvent, and by adjusting the amount of the initiator and the reaction temperature, It is preferable to obtain a low molecular weight compound in the resin composition used in the present invention. In particular, a solution polymerization method under a pressurized condition is also preferable from the viewpoint of minimizing the amount of the initiator used and minimizing the influence of the residual initiator.
[0066]
Examples of a monomer for obtaining a high molecular weight polymer component and a monomer for obtaining a low molecular weight polymer component include the following.
[0067]
For example, styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecyl Styrene derivatives such as styrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; unsaturated polyenes such as butadiene and isoprene; halogenation such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride Vinyls; vinyl acetate, vinyl propionate, vinyl benzoate, etc. Vinyl esters; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid (2-ethylhexyl), stearyl methacrylate, methacrylic acid Α-methylene aliphatic monocarboxylic esters such as phenyl, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, and n-acrylate Acrylates such as octyl, dodecyl acrylate, acrylic acid (2-ethylhexyl), stearyl acrylate, acrylic acid (2-chloroethyl), phenyl acrylate; vinyl methyl ester Vinyl ethers such as vinyl 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 carbazole, N-vinyl indole, N-vinyl pyrrolidone N-vinyl compounds; vinyl naphthalenes; acrylic acid derivatives or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers are used alone or as a mixture of two or more monomers.
[0068]
Among these, a combination of monomers that results in a styrene-based copolymer and a styrene-acryl-based copolymer is preferred.
[0069]
In addition, it is preferable that both the low-molecular-weight polymer component and the high-molecular-weight polymer component contain at least 65 parts by mass of a styrene-based polymer component or a styrene-based copolymer component from the viewpoint of miscibility.
[0070]
As a method for producing the binder resin composition, a solution blending method in which a high molecular weight polymer and a low molecular weight polymer are separately synthesized by a solution polymerization method, then mixed in a solution state, and then the solvent is removed, or an extruder A low-molecular-weight polymer obtained by a solution blending method or the like, which is melt-kneaded by dissolving in a monomer constituting a high-molecular-weight polymer obtained by dissolving the polymer, performing suspension polymerization, washing and drying, And a two-stage polymerization method for obtaining However, the dry blending method has problems in terms of uniform dispersion and compatibility. Although the two-stage polymerization method has many advantages in uniform dispersibility, the low molecular weight component can be increased to the high molecular weight component or more, a high molecular weight polymer having a large molecular weight can be synthesized, and unnecessary low molecular weight weight is reduced. The solution blending method is the most preferable because there are few problems such as by-products of coalescence. Further, as a method for introducing a predetermined acid value into the low molecular weight polymer component, a solution polymerization in which the acid value can be easily set as compared with an aqueous polymerization method is preferable.
[0071]
As the binder resin used in the toner of the present invention, the following polymers can also be used.
[0072]
For example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene and a substituted product thereof; a styrene-p-chlorostyrene copolymer, a styrene-vinyltoluene copolymer, and a styrene-vinylnaphthalene copolymer Styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene-based copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol Resin, natural modification Enol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, cumarone indene resin And petroleum-based resins can be used. Preferred binder resins include styrene copolymers and polyester resins. It is also possible to obtain an acid value by using a polyester resin.
[0073]
Next, the composition of the polyester resin will be described.
[0074]
Examples of the dihydric alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol represented by the formula (A) and derivatives thereof;
[0075]
Embedded image

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 to 10.)
[0076]
A diol represented by the formula (B);
[0077]
Embedded image

Where x 'and y' are integers equal to or greater than 0, and the average value of x '+ y' is 0 to 10. )
Is mentioned.
[0078]
Examples of the divalent acid component include benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride or anhydrides thereof, and lower alkyl esters; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid. Acids or anhydrides thereof, lower alkyl esters; alkenylsuccinic acids or alkylsuccinic acids such as n-dodecenylsuccinic acid, n-dodecylsuccinic acid, or anhydrides thereof, lower alkyl esters; fumaric acid, maleic acid, citraconic acid, itaconic acid Dicarboxylic acids and their anhydrides and lower alkyl esters; and dicarboxylic acids and their derivatives.
[0079]
Further, it is preferable to use a trivalent or higher valent alcohol component and a trivalent or higher valent acid component which also function as a crosslinking component.
[0080]
Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane Triol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene and the like Is mentioned.
[0081]
In addition, as the trivalent or higher polycarboxylic acid component in the present invention, for example, trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,5 7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empol trimer acid, and anhydrides and lower alkyl esters thereof;
Next formula
[0082]
Embedded image

(Wherein X is an alkylene group or alkenylene group having 1 to 30 carbon atoms having at least one side chain having 1 or more carbon atoms), such as tetracarboxylic acids, and anhydrides and lower alkyl esters thereof. And polyvalent carboxylic acids and derivatives thereof.
[0083]
It is preferable that the alcohol component used in the present invention is 40 to 60 mol%, preferably 45 to 55 mol%, and the acid component is 60 to 40 mol%, preferably 55 to 45 mol%.
[0084]
It is also preferred that the trivalent or higher polyvalent component accounts for 1 to 60 mol% of all components.
[0085]
The polyester resin can also be obtained by commonly known condensation polymerization.
[0086]
In the toner according to the present invention, in addition to the above-mentioned binder resin component, the following compounds may be contained at a ratio smaller than the content of the binder resin component. For example, silicone resin, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, and a copolymer of two or more kinds of α-olefins may be used.
[0087]
In the present invention, the following waxes are preferably contained in order to give the toner a releasing property. A wax having a melting point of 70 to 165 ° C. and a melt viscosity at 160 ° C. of 1000 mPa · s or less, and specific examples thereof include paraffin wax, microcrystalline wax, Fischer-Tropsch wax, montan wax, ethylene, propylene, and butene-1. Linear α-olefins such as pentene-1, hexene-1, heptene-1, octene-1, nonene-1 and decene-1, and branched α-olefins having a branched portion at the terminal; Examples include olefin homopolymers having different positions of saturated groups or copolymers thereof.
[0088]
Further, a modified wax obtained by forming a block copolymer with a vinyl monomer or by performing a graft modification may be used.
[0089]
The amount of the wax added is preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, per 100 parts by mass of the binder resin. Incidentally, two or more kinds of waxes may be added in combination.
[0090]
These waxes can be added to and mixed with the polymer component in advance in the production of the toner. In such a case, it is preferable to pre-dissolve the wax and the high molecular weight polymer in a solvent when preparing the polymer component, and then mix the low molecular weight polymer solution with the low molecular weight polymer solution. As a result, phase separation in a micro region is moderated, re-aggregation of high molecular weight components is suppressed, and a good dispersion state with a low molecular weight polymer is also obtained.
[0091]
The solid concentration of the polymer solution is preferably 5 to 70% by mass or less in consideration of dispersion efficiency, prevention of deterioration of the resin during stirring, operability, and the like. The preliminary solution of the high molecular weight polymer component and the wax is preferably The solid concentration of the low-molecular-weight polymer solution is preferably 5 to 60% by mass or less and 5 to 60% by mass or less.
[0092]
The method of dissolving or dispersing the high molecular weight polymer component and the wax is performed by stirring and mixing, and the stirring is preferably performed in a batch system or a continuous system.
[0093]
In the method of mixing the low molecular weight polymer solution, it is preferable to add 10 to 1000 parts by mass of the low molecular weight polymer solution to 100 parts by mass of the solid content of the preliminary solution and perform stirring and mixing. In this case, a batch type or a continuous type may be used.
[0094]
Examples of the organic solvent used when mixing the solution of the resin composition according to the present invention include benzene, toluene, xylene, Solvent Naphtha No. 1, Solvent Naphtha No. 2, Solvent Naphtha No. 3, cyclohexane, ethylbenzene, Solvesso 100, Solvesso 150, and minerals. Hydrocarbon solvents such as spirit; alcohol solvents such as methanol, ethanol, iso-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, iso-butyl alcohol, amyl alcohol, cyclohexanol; acetone, methyl ethyl ketone, methyl isobutyl ketone Solvents such as ethyl acetate, cyclohexanone, etc .; ester solvents such as ethyl acetate, n-butyl acetate, cellosolve acetate; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl Ether solvents such as carbitol. Among them, aromatic solvents, ketone solvents or ester solvents are preferred. These may be used in combination.
[0095]
The method of removing the organic solvent is preferably a method of heating the organic solvent solution of the polymer, removing 10 to 80% by mass of the organic solvent under normal pressure, and removing the remaining solvent under reduced pressure. At this time, the organic solvent solution is preferably maintained at a temperature within the range of 200 ° C. from the boiling point of the organic solvent used. Below the boiling point of the organic solvent, not only is the efficiency at the time of solvent distillation low, but also an unnecessary shear force is applied to the polymer in the organic solvent, and the redispersion of each constituent polymer is promoted, and in a micro state. May cause phase separation. On the other hand, when the temperature exceeds 200 ° C., the polymer is depolymerized, an oligomer is generated by molecular cleavage, and impurities are mixed into the resin composition, which is not preferable.
[0096]
The charge control agent used in the present invention contains at least one cyclic condensate.
[0097]
The first effect of this is that the charge decay characteristics are favorable. "Preferably, the charge attenuating property is preferable" means that the charge is maintained when left unattended, or that the charge is leaked so as not to have an excessive charge at the time of durability.
[0098]
Further, it is preferable to contain at least two or more condensates having different numbers of units. It is considered that the presence of condensates of various sizes allows small molecules to enter between large molecules, resulting in a change in electron conduction between the molecules. Here, the "number of units" is defined as one unit of the imidazole unit, and the number of the imidazole units is defined as the number of units.
[0099]
It has also been found that the toner after development behaves collectively by containing two or more kinds. By containing two or more types of condensates, transferability is improved, and transfer failure caused by irregularities of the paper during transfer is less likely to occur. Also, in the fixing step, scattering of the fixing is reduced. This also seems to be related to the decay of charge after development.
[0100]
The second effect of containing two or more kinds is that the yield at the time of synthesis is improved and the cost is reduced. This is because condensates having different numbers of units have different monomer conditions suitable for the reaction. Therefore, it is considered that the remaining monomer in the course of the reaction only has to satisfy any one of the conditions, and that the amount of the monomer that does not contribute to the reaction decreases.
[0101]
When two or more condensates having different numbers of units are contained, the crystallinity of the obtained powder is reduced. Therefore, fine particles can be formed with a weak force, and as a result, the dispersibility in the toner resin is improved.
[0102]
These effects are further improved when the number of units is three or more, and stable charging properties can be obtained. Further, at this time, the abundance ratio of one type of condensate is preferably 90% or less, more preferably 80% or less, particularly 70% or less, and more preferably 60% or less. The above-mentioned effects become more pronounced.
[0103]
Further, the imidazole condensate conventionally proposed as a charge control agent is a chain product. Since the chain condensate is excellent in dispersibility, the chargeability is slightly inferior, but uniform chargeability is easily obtained. Since a cyclic compound is excellent in chargeability, a high charge amount can be obtained. The adverse effects of chain products are improved by using cyclic condensates.
[0104]
When a chain condensate and a cyclic condensate are used at the same time, the good dispersibility of the chain is utilized, so that the chargeability of the ring is higher and the speed of charging rises. The condensate having a chain structure softens from a relatively low temperature, like a general resin. When this component and the cyclic component are mixed, a very good charging property is obtained as a result. This seems to be the following phenomenon. The cyclic component has high chargeability. On the other hand, the chain component does not have a high charge amount, but is easily softened and has good dispersibility. Further, since both have basically the same skeleton, they have an affinity and a fine mixed state is easily formed. In other words, the chain component is considered to be a dispersing aid for the cyclic component, so that a uniform and high charge can be achieved.
[0105]
As described above, when the condensate of the present invention is contained in the toner, a toner having a uniform charge amount distribution at a high level can be obtained. For this reason, the high-temperature and high-humidity environment is an environment in which toner scattering is likely to occur. However, by containing the condensate of the present invention, toner scattering is significantly reduced.
[0106]
The condensate of the present invention can be obtained by heating an imidazole and an aldehyde in the presence of an inorganic alkali catalyst. A chain condensate and a cyclic condensate may be selectively obtained and then mixed. In order to selectively obtain them, the conditions for adding the inorganic alkali may be adjusted, and the conditions for washing and extraction may be further adjusted. By adding a plurality of inorganic alkalis, the types of condensates having different numbers of units can be increased. Various mixtures of chain condensates and cyclic condensates can be obtained by adjusting the heating temperature, the timing of adding the raw materials, the synthesis conditions such as the synthesis concentration, the amount of the solvent, the alkali metal, and the pH. As the solvent used for the synthesis, alcohols such as methanol, ethanol, propanol, isopropanol and butanol, and glycols such as ethylene glycol, ethylene glycol alkyl ether and propylene glycol are preferably used. Solvents that can be used for washing and extraction include acetone, methyl ethyl ketone, alcohol, ether, hexane, dioxane, toluene, chloroform, tetrahydrofuran, dimethyl sulfoxide and the like.
[0107]
The terminal of the chain condensate of the present invention is preferably a hydrogen atom, an alkyl group, or an alkyl group containing a hydroxy group, and is preferably a hydrogen or alkyl group which is advantageous in terms of charge amount in a high humidity environment. For example, in the general formula (II), one is condensed with an aldehyde, one is a hydrogen, an alkyl group, or a hydroxyalkyl group, and in the general formula (IV), one is condensed on an imidazole, and one is a hydrogen or a hydroxy group. It becomes.
[0108]
The abundance ratio of the cyclic condensate in the condensate of the present invention is preferably 5% or more. More preferably, it is 5 to 95%. More preferably, it is 10% to 90%. If the amount of the ring is less than 5%, the formulation exhibiting the effect of improving the chargeability is limited. In addition, since the chain-like material is contained in an amount of 5 to 95%, the toner is uniformly dispersed, thereby quickly reaching charging suitable for development, and the toner supplied to the developing device is quickly replaced and consumed. When the content is 10 to 90%, replacement in a low humidity environment is particularly fast. This makes it difficult to generate deteriorated toner at the time of durability, and improves image quality. Further, generation of toner having excessive charge (so-called charge-up) is reduced, and the transition of image density is stabilized.
[0109]
Here, the unit having one unit is included in the chain condensate. Even if the number of units is the same, the chain condensate and the cyclic condensate are treated as having different units. Further, the substituent Rn of each unit constituting the condensate may be different or the same for each unit, and the permutation thereof may be arbitrary.
[0110]
In the present invention, the condensate preferably contains units represented by the following general formulas (I), (II), (III) and (IV).
[0111]
Embedded image

[Wherein, R ₁ And R ₃ Is a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent or an alicyclic group which may have a substituent Represents a group; R ₂ Is a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, an alicyclic group which may have a substituent R, an alkyl group having a hydroxy group or an aralkyl group having a hydroxy group; ₄ Represents a hydrogen atom or a hydroxy group, and formulas (II) and (IV) represent terminal units of a chain condensate. ]
The structure of the condensate of the present invention is applicable as long as the substituent Rn in the general formulas (I) to (IV) does not inhibit the condensation reaction.
[0112]
Substituent R in general formulas (I) and (II) ₁ In the case where the compound is an aryl group, an aralkyl group, or an alicyclic group which may have an alkyl group or a substituent, the charge amount is high and the charge rise is likely to be good. Among them, an alkyl group which may have a substituent is preferable, and more preferably an alkyl group having 21 or less carbon atoms, particularly one having an alkyl group having 1 to 15 carbon atoms has improved charge retention. So good. Further, by having a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a phenyl group, and a benzyl group, Since the charge amount is maintained, the control in transfer and fixing becomes easy. As a result, disturbance of images during transfer and fixing is reduced.
[0113]
The substituent R in the general formula (II) ₂ In the above, a hydrogen atom is preferable, and in others, an alkyl group, an aralkyl group, and an aryl group are preferable.
[0114]
The substituent R in the general formulas (III) and (IV) ₃ In the above, a hydrogen atom is preferable, but in other cases, a methyl group does not hinder the condensation reaction, and it is preferable because impurities harmful to toner performance are hardly contained.
[0115]
Substituent R in general formula (IV) ₄ In the above, a hydrogen atom is preferable, but in other cases, a hydroxy group, a siloxy group, an alkyl group, and a silyl group are effective in improving the charge amount.
[0116]
Condensates having two or more units having different substituents are also preferable. By using two or more kinds, it is possible to adjust the crystallinity of the obtained powder, the dispersibility in the toner, and the way of rising of the charge. As a combination, for example, a combination of alkyl groups having different carbon numbers is preferable.
[0117]
In the present invention, the number of units of the condensate needs to include two or more in the case of a cyclic one, and three or more in the case of a chain, more preferably 3 to 50, and further preferably 3 to 30. It is preferable to contain 3 to 10 condensates, particularly from the viewpoint of dispersibility.
[0118]
As a method for incorporating the compound of the present invention into a toner, there are a method of adding the compound inside the toner and a method of externally adding the compound. When added internally, a preferable addition amount is 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the binder resin. When externally added, the amount is preferably 0.01 to 5 parts by mass, and particularly preferably mechanochemically fixed to the toner surface.
[0119]
The compounds of the present invention can also be used in combination with known charge control agents as described in the prior art.
[0120]
Hereinafter, specific structures of the condensate of the present invention will be exemplified.
[0121]
The abundance ratio is obtained by measuring the molecular weight distribution using FD-MS (electrolysis desorption mass spectrometry), and determining the intensity ratio of the m / z peak as the abundance ratio. The molecular weight of each unit is calculated, the molecular weight of the condensate composed of the unit is calculated, and the unit configuration is determined.
[0122]
Condensate (1):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0123]
Embedded image

Example of structural formula
[0124]
Embedded image

[0125]
[Table 1]

[0126]
Condensate (2):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0127]
Embedded image

Example of structural formula
[0128]
Embedded image

[0129]
[Table 2]

[0130]
Condensate (3):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0131]
Embedded image

Example of structural formula
[0132]
Embedded image

[0133]
[Table 3]

[0134]
Condensate (4):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0135]
Embedded image

Example of structural formula
[0136]
Embedded image

[0137]
[Table 4]

[0138]
Condensate (5):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0139]
Embedded image

Example of structural formula
[0140]
Embedded image

[0141]
[Table 5]

[0142]
Condensate (6):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0143]
Embedded image

Example of structural formula
[0144]
Embedded image

[0145]
[Table 6]

[0146]
Condensate (7):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0147]
Embedded image

Example of structural formula
[0148]
Embedded image

[0149]
[Table 7]

[0150]
Condensate (8):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0151]
Embedded image

Example of structural formula
[0152]
Embedded image

[0153]
[Table 8]

[0154]
Condensate (9):
A mixture of condensates composed of the following units
A and formaldehyde as starting materials
[0155]
Embedded image

Example of structural formula
[0156]
Embedded image

[0157]
[Table 9]

[0158]
Condensate (10):
A mixture of condensates composed of at least one unit selected from the following two units
Starting materials are imidazole and formaldehyde where the linking group is hydrogen
[0159]
Embedded image

Example of structural formula
[0160]
Embedded image

[0161]
[Table 10]

[0162]
Condensate (11):
A mixture of condensates composed of at least one unit selected from the following two units
Starting materials are imidazole and formaldehyde where the linking group is hydrogen
[0163]
Embedded image

Example of structural formula
[0164]
Embedded image

[0165]
[Table 11]

[0166]
Condensate (12):
A mixture of condensates composed of at least one unit selected from the following three units
Starting materials are imidazole and formaldehyde where the linking group is hydrogen
[0167]
Embedded image

Example of structural formula
[0168]
Embedded image

[0169]
[Table 12]

[0170]
Condensate (13):
A mixture of condensates composed of at least one unit selected from the following three units
Starting materials are imidazole and formaldehyde where the linking group is hydrogen
[0171]
Embedded image

Example of structural formula
[0172]
Embedded image

[0173]
[Table 13]

[0174]
Condensate (14):
A mixture of condensates composed of at least one unit selected from the following four units
Starting materials are imidazole and formaldehyde where the linking group is hydrogen
[0175]
Embedded image

Example of structural formula
[0176]
Embedded image

[0177]
[Table 14]

[0178]
Condensate (15):
A mixture of condensates composed of at least one unit selected from the units of group A and group B
Starting materials are imidazole, formaldehyde, and acetaldehyde in which the linking group is hydrogen
[0179]
Embedded image

Example of structural formula
[0180]
Embedded image

[0181]
[Table 15]

[0182]
Condensate (16):
A mixture of condensates composed of at least one unit selected from the units of group A and group B
Starting materials are imidazole, formaldehyde, and acetaldehyde in which the linking group is hydrogen
[0183]
Embedded image

Example of structural formula
[0184]
Embedded image

[0185]
[Table 16]

[0186]
Condensate (17):
A mixture of condensates composed of at least one unit selected from the units of group A and group B
Starting materials are imidazole, formaldehyde, and acetaldehyde in which the linking group is hydrogen
[0187]
Embedded image

Example of structural formula
[0188]
Embedded image

[0189]
[Table 17]

[0190]
Condensate (18):
A mixture of condensates composed of the following units
A and acetaldehyde are starting materials
[0191]
Embedded image

Example of structural formula
[0192]
Embedded image

[0193]
[Table 18]

[0194]
Condensate (19):
A mixture of condensates composed of the following units
A and benzaldehyde are starting materials
[0195]
Embedded image

Example of structural formula
[0196]
Embedded image

[0197]
[Table 19]

[0198]
Condensate (20):
A mixture of condensates composed of the following units
A and propionaldehyde are starting materials
[0199]
Embedded image

Example of structural formula
[0200]
Embedded image

[0201]
[Table 20]

[0202]
The coloring agent that can be used in the toner of the present invention includes any appropriate pigment or dye. For example, pigments include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, red bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary to maintain the optical density of the fixed image, and are preferably added in an amount of 0.1 to 20 parts by mass, preferably 0.2 to 10 parts by mass, per 100 parts by mass of the binder resin. A dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and 0.1 to 20 parts by mass, preferably 0.3 to 10 parts by mass, per 100 parts by mass of the binder resin is good. .
[0203]
Further, in the toner of the present invention, a magnetic substance may be used as a coloring agent, and the magnetic substance may be used as a magnetic toner.
[0204]
Examples of the magnetic substance used in the present invention include iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, Alloys of metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium and mixtures thereof are used, and those containing a silicon element on the surface or inside of the magnetic material are preferable.
[0205]
As a result of intensive studies by the present inventors, the inclusion of the silicon element in the magnetic substance has a uniform particle size distribution of the magnetic substance, and the dispersion of the magnetic substance in the toner is several steps better than when the silicon element is not contained. It turned out to be. Further, when a magnetic material containing a silicon element is contained in the toner, even in a toner having an average particle diameter of 10 μm or less, charging uniformity is improved, toner cohesion can be suppressed, and fluidity of the toner is improved. The triboelectric charge is improved. As a result, it was found that the initial image density was stable and the image fog was suppressed to a level that caused almost no problem.
[0206]
The content of the silicon element contained in the magnetic material is preferably 0.05 to 10% by mass based on the magnetic material. It is more preferably 0.1 to 7% by mass, and desirably 0.2 to 5% by mass. If the content of the silicon element in the magnetic material is less than 0.05% by mass, the effect of the addition of the silicon element cannot be obtained, and the triboelectric charge amount of the toner tends to be nonuniform, and image fog increases. If the content is more than 10% by mass, the image fog is improved, but the surface of the toner carrier is contaminated, the image density is reduced, and ghosts are easily generated.
[0207]
The amount of silicon element in the magnetic material in the present invention was measured by performing X-ray fluorescence analysis using a fluorescent X-ray analyzer SYSTEM3080 (manufactured by Rigaku Corporation) in accordance with JIS K0119 “General rules for X-ray fluorescence analysis”. .
[0208]
As the shape of the magnetic material used in the present invention, a hexahedron, an octahedron, a decahedron, a dodecahedron, a tetrahedron, or a polyhedron having more surfaces, a needle, a scale, a sphere, an irregular shape and the like Is used. Among them, a polyhedron is preferably used. In the case of a magnetic material having a polyhedral shape, it is possible to physically prevent the magnetic material from detaching from the toner particles from the shape.
[0209]
The magnetic material used for the toner in the present invention has a BET specific surface area of 1 to 40 m by a nitrogen gas adsorption method. ² / G, preferably 2 to 30 m ² / G, more preferably 3 to 20 m ² / G is good. As a measurement method, according to the BET method, a nitrogen gas is adsorbed on the sample surface using a specific surface area measuring apparatus: Auto Soap 1 (manufactured by Yuasa Ionics), and the specific surface area is calculated using the BET multipoint method.
[0210]
The saturation magnetization of the magnetic material is 5 to 200 Am in a magnetic field of 795.8 kA / m. ² / Kg, preferably 10 to 150 Am ² / Kg range.
[0211]
Further, the residual magnetization of the magnetic material is 1 to 100 Am in a magnetic field of 795.8 kA / m. ² / Kg, preferably 1-70 Am ² / Kg range.
[0212]
The average particle size of the magnetic material is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and particularly preferably 0.1 to 0.4 μm.
[0213]
In the present invention, the amount of the magnetic substance contained in the toner is 10 to 200 parts by mass, preferably 20 to 170 parts by mass, and more preferably 30 to 150 parts by mass with respect to 100 parts by mass of the binder resin.
[0214]
In the present invention, the shape of the magnetic body is observed by a transmission electron microscope and a scanning electron microscope.
[0215]
The magnetic properties of the magnetic material are values measured using an "oscillating sample magnetometer VSM-3S-15" (manufactured by Toei Kogyo Co., Ltd.) under an external magnetic field of 795.8 kA / m.
[0216]
In the toner of the present invention, it is preferable to add silica fine powder in order to improve charge stability, developability, fluidity, and durability.
[0219]
The silica fine powder used in the present invention has a specific surface area of 30 m by the BET method by nitrogen adsorption. ² / G or more, especially 50 to 400 m ² / G gives good results. It is preferable to use 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass of silica fine powder with respect to 100 parts by mass of the toner.
[0218]
In addition, the silica fine powder used in the present invention may contain, if necessary, a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, a functional group for the purpose of hydrophobicity, charge control, and the like. It is also preferable that the silane compound is treated with a treating agent such as a silane compound or another organosilicon compound, or in combination with various treating agents.
[0219]
If necessary, other external additives may be added to the toner of the present invention.
[0220]
For example, there are resin fine particles and inorganic fine particles which function as a charge auxiliary agent, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a releasing agent at the time of fixing with a heat roller, a lubricant, an abrasive and the like.
[0221]
For example, examples of the lubricant include Teflon powder, zinc stearate powder, polyvinylidene fluoride powder and the like, and among them, polyvinylidene fluoride powder is preferable. Examples of the polishing agent include cerium oxide powder, silicon carbide powder, and strontium titanate powder, and among them, strontium titanate powder is preferable. Examples of the fluidity-imparting agent include a titanium oxide powder and an aluminum oxide powder, and among them, a hydrophobic one is preferable. Examples of the conductivity imparting agent include carbon black powder, zinc oxide powder, antimony oxide powder, and tin oxide powder. Still further, a small amount of white fine particles and black fine particles of opposite polarity can be used as a developing property improver.
[0222]
To prepare the toner of the present invention, a binder resin, a colorant, an imidazole derivative, and if necessary, a magnetic substance, a wax, a metal salt or metal complex, a pigment or a dye, other additives, and the like, are added to a Henschel mixer, a ball mill. After sufficiently mixing with a mixer such as a heating roll, kneader, melt kneading using a hot kneader such as an extruder, after cooling and solidification, pulverization and classification, and further, if necessary, the desired additive Henschel The toner of the present invention can be obtained by sufficiently mixing with a mixer such as a mixer.
[0223]
Next, the configuration of the sleeve which is the developer carrying member of the present invention will be described with reference to FIG.
[0224]
The sleeve with the developer carrier of the present invention has a cylindrical substrate and a coating layer (resin layer) covering the surface of the substrate. The resin layer 1 contains a binder resin 4, and in some cases, a conductive substance 2, a filler 3, a solid lubricant 5, and the like, and is coated on a cylindrical substrate 6. When the conductive material is contained, the resin layer 1 is conductive, so that excessive charging of the toner can be prevented. When the filler 3 is contained, abrasion of the resin 1 by the toner is prevented, and the charging property of the filler 3 can appropriately control the charging of the toner. When the solid lubricant 5 is contained, the releasability of the toner and the sleeve is improved, and as a result, the fusion of the toner onto the sleeve can be prevented.
[0225]
In the sleeve of the present invention, when the resin layer contains a conductive substance, the volume resistance of the resin layer is 10%. ⁶ Ω · cm or less, preferably 10 ³ It is preferable that the resistance is Ω · cm or less. The volume resistance of the resin layer is 10 ⁶ If it exceeds Ω · cm, charge-up of the toner is likely to occur, which may cause the occurrence of blotches and the deterioration of development characteristics.
[0226]
The volume resistance of the resin layer is measured by using a low-resistivity lorester (manufactured by Mitsubishi Yuka Co., Ltd.), using a composition as a paint, coating and drying on an insulating sheet with a bar coater, cutting to 10 cm × 10 cm. Can be.
[0227]
The surface roughness of the resin layer is preferably in the range of 0.2 to 3.5 μm in JIS center line average roughness (Ra). If Ra is less than 0.2 μm, the charge amount of the toner in the vicinity of the sleeve becomes too high, the toner is attracted to the sleeve by the mirroring power, new toner cannot be charged by the sleeve, and the developing property is insufficient. Become. When Ra exceeds 3.5 μm, the toner coating amount on the sleeve is excessively increased, so that a sufficient charge amount of the toner cannot be obtained, and the toner becomes non-uniformly charged, which causes a reduction in image density and density unevenness.
[0228]
Next, each material constituting the resin layer 1 will be described.
[0229]
In FIG. 1, examples of the conductive substance 2 include metal powders such as aluminum, copper, nickel, and silver; metal oxides such as antimony oxide, indium oxide, and tin oxide; and carbon allotropes such as carbon fiber, carbon black, and graphite. No. Among them, carbon black is particularly excellent in electric conductivity, and is preferably used because it can be filled with a polymer material to impart conductivity, or the conductivity can be obtained to some extent by controlling the amount of addition. The carbon black used in the present invention has a number average particle size of 1 μm or less, preferably 0.01 μm to 0.8 μm. If the number average particle size of the carbon black exceeds 1 μm, it becomes difficult to control the volume resistance of the resin layer, which is not preferable.
[0230]
The amount of the conductive substance to be used is preferably 0.1 to 300 parts by mass, more preferably 1 to 100 parts by mass, based on 100 parts by mass of the binder resin.
[0231]
Examples of the filler 3 include inorganic compounds such as alumina, asbestos, glass fiber, calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, silica, and calcium silicate; phenol resins, epoxy resins, melamine resins, silicone resins, PMMA, Methacrylate terpolymer (for example, polystyrene / n-butyl methacrylate / silane terpolymer), styrene-butadiene copolymer, polycaprolactone; nitrogen-containing compounds such as polycaprolactam, polyvinylpyridine, and polyamide; polyvinylidene fluoride, polyvinyl chloride , Polytetrafluoroethylene, polytetrachlorofluoroethylene, perfluoroalkoxylated ethylene, polytetrafluoroalkoxyethylene, fluorinated ethylene propylene-polytetraf Oroechiren copolymer, trifluorochloroethylene - highly halogenated polymers such as vinyl chloride copolymers; Other polycarbonates, polyesters, and the like. Among these, silica and alumina are preferably used because they have their own hardness and charge controllability for toner.
[0232]
The amount of the filler to be used is preferably 0.1 to 500 parts by mass, more preferably 1 to 200 parts by mass, based on 100 parts by mass of the binder resin.
[0233]
Examples of the solid lubricant 5 include molybdenum disulfide, boron nitride, graphite, graphite fluoride, silver-niobium selenide, calcium chloride-graphite, and talc. Among these, graphite is preferably used because it has conductivity as well as lubricity, has a function of reducing toner having an excessively high charge, and having a charge amount suitable for development.
[0234]
The amount of the solid lubricant to be used is preferably 0.1 to 300 parts by mass, more preferably 1 to 150 parts by mass, based on 100 parts by mass of the binder resin.
[0235]
Examples of the binder resin 4 in which the conductive substance 2 and, in some cases, the filler 3 and the solid lubricant 5 are dispersed, include a phenolic resin, an epoxy resin, a polyamide resin, a polyester resin, a polycarbonate resin, and a polyolefin. Known resins such as a resin, a silicone resin, a fluorine resin, a styrene resin, and an acrylic resin are used. Particularly, a thermosetting or photocurable resin is preferable.
[0236]
Further, in order to suitably expose the conductive material in the resin layer on the sleeve surface in the present invention, or a filler or a solid lubricant to the surface, or to smooth the surface to produce a uniform uneven surface, By performing a smoothing treatment on the surface by means such as polishing described below, more preferable performance can be imparted. In particular, it has an effect on the vertical streak phenomenon that occurs in solid black and halftone images and the rise of the initial image density, and is particularly effective under high temperature and high humidity.
[0237]
The operation of the present invention will be described with reference to FIG. In FIG. 2A, the coating layer (resin layer) 501 contains a solid lubricant 502, a conductive substance 503, a filler 504, and a binder resin 505, and is coated on a cylindrical base 506. This is polished with a belt-like abrasive to which felt or abrasive grains are adhered, so that the surface unevenness of the sleeve can be uniformly finished as shown in FIG. 2 (B). As a result, only the toner that has been frictionally charged with the sleeve is conveyed to the developing area. Therefore, it is considered that the above effects can be obtained.
[0238]
Even after the smoothing treatment as described above, the surface of the coat layer preferably retains irregularities in the range of 0.2 to 3.5 μm in Ra according to JIS B0601, more preferably 0.3 to 3.5 μm. It is about 2.5 μm. The reason is the same as above.
[0239]
Next, a description will be given of a developing method in which the developing sleeve as the developer carrying member of the present invention is incorporated.
[0240]
In FIG. 3, an image carrier, for example, an electrophotographic photosensitive drum 7 that carries an electrostatic latent image formed by a known process is rotated in the direction of arrow B. The developing sleeve 14 as a developer carrying member carries the magnetic toner 10 as a one-component magnetic developer supplied from the hopper 9 and rotates in the direction of arrow A so that the developing sleeve 14 and the photosensitive drum 7 are separated. The magnetic toner 10 is transported to the developing section D facing the same. A magnet 11 is disposed in the developing sleeve 14 for magnetically attracting and holding the magnetic toner 10 on the developing sleeve 14. The magnetic toner 10 obtains a triboelectric charge that can develop the electrostatic latent image on the photosensitive drum 7 by friction with the developing sleeve 14.
[0241]
In order to regulate the layer thickness of the magnetic toner 10 conveyed to the developing section D, a regulating blade 8 made of a ferromagnetic metal faces the developing sleeve 14 with a gap width of about 200 to 300 μm from the surface of the developing sleeve 14. Thus, it is hung from the hopper 9. When the magnetic lines of force from the magnetic pole N1 of the magnet 11 are concentrated on the blade 8, a thin layer of the magnetic toner 10 is formed on the developing sleeve 14. A non-magnetic blade can be used as the blade 8.
[0242]
The thickness of the thin layer of the magnetic toner 10 formed on the developing sleeve 14 is preferably smaller than the minimum gap between the developing sleeve 14 and the photosensitive drum 7 in the developing section D. The present invention is particularly effective for a developing device of a system for developing an electrostatic latent image with such a thin toner layer, that is, a non-contact type developing device. However, the present invention is also applicable to a developing device in which the thickness of the toner layer in the developing section is equal to or greater than the minimum gap between the developing sleeve 14 and the photosensitive drum 7, that is, a contact type developing device.
[0243]
For the sake of simplicity, the following description will be made using a non-contact developing device as an example.
[0244]
A power supply 15 applies a developing bias voltage to the developing sleeve 14 in order to fly the magnetic toner 10 which is a one-component magnetic developer carried on the developing sleeve 14. When a DC voltage is used as the developing bias voltage, a voltage having a value between the potential of the image portion of the electrostatic latent image (the region where the magnetic toner 10 adheres and is visualized) and the potential of the background portion is used. Preferably, it is applied to the sleeve 14. On the other hand, in order to increase the density of the developed image or improve the gradation, an alternating bias voltage may be applied to the developing sleeve 14 to form an oscillating electric field whose direction is alternately reversed in the developing unit D. In this case, it is preferable to apply to the developing sleeve 14 an alternating bias voltage on which a DC voltage component having a value between the potential of the image portion and the potential of the background portion is superimposed.
[0245]
Also, in so-called regular development, in which toner is attached to a high potential portion of an electrostatic latent image having a high potential portion and a low potential portion to visualize the toner, a toner charged to a polarity opposite to the polarity of the electrostatic latent image is used. On the other hand, in so-called reversal development in which toner is attached to a low-potential portion of an electrostatic latent image to make it visible, toner that is charged to the same polarity as the polarity of the electrostatic latent image is used. Note that the high potential and the low potential are expressed by absolute values. In any case, the magnetic toner 10 is charged to a polarity for developing the electrostatic latent image by friction with the developing sleeve 14.
[0246]
FIG. 4 is a configuration diagram showing another embodiment of the present invention.
[0247]
In the developing device of FIG. 4, as a member for regulating the layer thickness of the magnetic toner 10 on the developing sleeve 14, a material having rubber elasticity such as urethane rubber or silicone rubber or a metal elasticity such as phosphor bronze or stainless steel is used. It is characterized in that an elastic plate 17 made of a material or the like is used, and this elastic plate 17 is pressed against the developing sleeve 14. In such a developing device, a thinner toner layer can be formed on the developing sleeve 8. The other configuration of the developing device of FIG. 4 is basically the same as that of the developing device shown in FIG. 3. In FIG. 4, the same reference numerals as those shown in FIG. 3 denote the same members.
[0248]
In the developing device shown in FIG. 4, in which the toner layer is formed on the developing sleeve 14 as described above, the toner is rubbed on the developing sleeve 14 by the elastic plate 17, so that the amount of triboelectric charge of the toner increases, and The concentration is improved. Such a developing device is used for a non-magnetic one-component toner.
[0249]
Next, an example of an image forming method having a contact charging / transfer method used in the present invention will be described with reference to the schematic configuration diagram of FIG.
[0250]
Reference numeral 801 denotes a rotating drum type photoconductor, which is rotated at a predetermined peripheral speed (process speed) clockwise in the drawing. Reference numeral 802 denotes a charging roller which is pressed against the surface of the photoconductor 801 with a pressing force, and is driven to rotate as the photoconductor 801 rotates. 803 denotes a charging bias current V for applying a voltage to the charging roller 802. ₂ When a bias is applied to the charging roller 802, the surface of the photoconductor 801 is charged to a predetermined polarity and potential. Next, an electrostatic image is formed by the image exposure 804, and is sequentially visualized as a toner image by the developing unit 805.
[0251]
The bias V is applied to the developing sleeve constituting the developing unit 805 by the bias applying unit 813. ₁ Is applied. The toner image formed on the latent image holding member by development is ₃ Is electrostatically transferred to the transfer material 808 by the contact transfer unit 806 to which the toner image is applied, and the toner image on the transfer material is heated and pressurized and fixed by the heating and pressurizing unit 811. On the surface of the photoconductor 801 after transfer of the toner image, adhered contaminants such as untransferred toner are cleaned by a cleaning device 809 having an elastic cleaning blade pressed against the photoconductor 801 in a counter direction, and further, by a charge-removal exposure device 810. The charge is removed and an image is repeatedly formed.
[0252]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.
[0253]
(Synthesis example of binder resin)
<Resin synthesis example 1>
79.0 parts by mass of styrene
n-butyl acrylate 20.0 parts by mass
0.8 parts by mass of monobutyl malate
0.2 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile)
[0254]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin a.
[0255]
Resin a 30.0 parts by mass
56.0 parts by mass of styrene
n-butyl acrylate 12.2 parts by mass
Monobutyl malate 1.4 parts by mass
0.4 parts by mass of divinylbenzene
1.0 parts by mass of di-tert-butyl peroxide
[0256]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as resin A. The acid value of this resin A was 5.2.
[0257]
<Resin synthesis example 2>
79.0 parts by mass of styrene
n-butyl acrylate 21.0 parts by mass
2,2′-bis (4,4-di-tert-butyl
0.3 parts by mass of peroxycyclohexyl) propane
[0258]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Furthermore, the polymerization was completed under xylene reflux.
[0259]
82.0 parts by mass of styrene
17.0 parts by mass of n-butyl acrylate
Monobutyl malate 1.0 part by mass
1.0 parts by mass of di-tert-butyl peroxide
[0260]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solutions were mixed such that the mass ratio of the resin components became the former 25 and the latter 75, and then the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin B. The acid value of this resin B was 2.3.
[0261]
<Resin synthesis example 3>
77.0 parts by mass of styrene
n-butyl acrylate 20.0 parts by mass
Monobutyl maleate 3.0 parts by mass
2,2′-bis (4,4-di-tert-butyl
0.3 parts by mass of peroxycyclohexyl) propane
[0262]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Furthermore, the polymerization was completed under xylene reflux.
[0263]
78.0 parts by mass of styrene
18.0 parts by mass of n-butyl acrylate
Methacrylic acid 4.0 parts by mass
1.0 parts by mass of di-tert-butyl peroxide
[0264]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under reflux of xylene, and the solutions were mixed such that the mass ratio of the resin components became the former 4 and the latter 6, and then the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin C. The acid value of this resin C was 18.8.
[0265]
<Resin synthesis example 4>
73.7 parts by mass of styrene
Butyl acrylate 22.0 parts by mass
Acrylic acid 3.5 parts by mass
0.8 parts by mass of divinylbenzene
0.8 parts by mass of di-tert-butyl peroxide
[0266]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as resin D. The acid value of this resin D was 27.0.
[0267]
<Resin synthesis example 5>
72.7 parts by mass of styrene
Butyl acrylate 22.0 parts by mass
Acrylic acid 4.5 parts by mass
0.8 parts by mass of divinylbenzene
0.8 parts by mass of di-tert-butyl peroxide
[0268]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin E. The acid value of this resin E was 34.8.
[0269]
<Resin Comparative Synthesis Example 1>
80.0 parts by mass of styrene
n-butyl acrylate 20.0 parts by mass
2,2′-bis (4,4-di-tert-butyl
0.3 parts by mass of peroxycyclohexyl) propane
[0270]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Furthermore, the polymerization was completed under xylene reflux.
[0271]
83.0 parts by mass of styrene
17.0 parts by mass of n-butyl acrylate
1.0 parts by mass of di-tert-butyl peroxide
[0272]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under reflux of xylene, and the solutions were mixed such that the mass ratio of the resin components became the former 3 and the latter 7, and then the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin F. The acid value of this resin F was 0.1.
[0273]
<Resin Comparative Synthesis Example 2>
68.7 parts by mass of styrene
Butyl acrylate 22.0 parts by mass
8.5 parts by mass of methacrylic acid
0.8 parts by mass of divinylbenzene
0.8 parts by mass of di-tert-butyl peroxide
[0274]
The above raw material was dropped into 200 parts by mass of heated xylene over 4 hours. Further, the polymerization was completed under xylene reflux, and the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a resin G. The acid value of this resin G was 55.2.
[0275]
(Example of manufacturing a developer carrier having a resin layer formed on the surface)
<Development sleeve manufacturing example 1>
Phenol resin intermediate 125 parts by mass
5 parts by mass of carbon black
45 parts by mass of crystalline graphite
Methanol 41 parts by mass
284 parts by mass of isopropyl alcohol
The methanol solution of the phenol resin intermediate was diluted with isopropyl alcohol (IPA), carbon black and crystalline graphite were added, and the mixture was dispersed by a sand mill using glass beads. Next, a resin layer was applied on the sleeve using this paint.
[0276]
As a developing sleeve, the surface of a stainless steel cylindrical tube having an outer diameter of 20 mm and a wall thickness of 0.8 mm was polished to have a run-out of 10 μm or less and a surface roughness of 4 μm or less in Rz notation. The sleeve was set up vertically, rotated at a constant speed, masked at the upper and lower ends, and the above-mentioned paint was applied while lowering the spray gun at a constant speed. The masking width at both ends of the sleeve was set to 3 mm. After drying and curing at 160 ° C. for 20 minutes in a drying furnace, a belt-shaped felt is rubbed against the surface of the resin-coated sleeve with a load of 4 kgf, and the surface is polished. Got a sleeve.
[0277]
The resin layer had a thickness of 10 μm, a surface roughness Ra of 0.86 μm on average at six points, a volume resistance of 4 Ω · cm, and a pencil hardness of 2H when measured. A magnet was inserted into this sleeve, and flanges were attached to both ends to form a developing sleeve 1.
[0278]
<Developing sleeve manufacturing example 2>
Phenol resin intermediate 125 parts by mass
5 parts by mass of carbon black
45 parts by mass of crystalline graphite
Surface-treated silica fine powder 25 parts by mass
(Specific surface area by BET is about 130m ² / G dry silica fine powder treated with methyltrimethoxysilane
Methanol 58 parts by mass
408 parts by mass of isopropyl alcohol
The above materials were dispersed using a sand mill. The methanol solution of the phenol resin intermediate was diluted with a part of isopropyl alcohol (IPA), carbon black and crystalline graphite were added, and the mixture was dispersed by a sand mill using glass beads. Here, the above treated silica dispersed in the remaining IPA was further added as a filler, and the sand mill dispersion was further advanced.
[0279]
Next, using this coating material, a resin layer was coated on the sleeve in the same manner as in Production Example 1 for a resin-coated developing sleeve, and then the surface was polished. The thickness of the conductive resin layer was 15 μm, the surface roughness Ra was 1.08 μm on average at six points, the volume resistance was 7 Ω · cm, and the pencil hardness was measured. A magnet was inserted into this sleeve, and flanges were attached to both ends to form a developing sleeve 2.
[0280]
<Developing sleeve manufacturing example 3>
Using the paint used in the developing sleeve production example 1, the surface of an aluminum cylindrical tube having an outer diameter of 12 mm and a wall thickness of 0.8 mm was polished as a developing sleeve, and the cylindrical tube had a runout of 10 μm or less and a surface roughness of less than 10 μm. It was used at 4 μm or less in Rz notation. The sleeve was set up vertically, rotated at a constant speed, masked at the upper and lower ends, and the above-mentioned paint was applied while lowering the spray gun at a constant speed. The masking width at both ends of the sleeve was set to 3 mm. After drying and curing at 160 ° C. for 20 minutes in a drying furnace, a belt-shaped felt is rubbed against the surface of the resin-coated sleeve with a load of 4 kgf, and the surface is polished. Got a sleeve.
[0281]
The resin layer had a thickness of 11 μm, a surface roughness Ra of 0.97 μm on an average of 6 points, a volume resistance of 4 Ω · cm, and a pencil hardness of 2H. A flange was attached to both ends of this sleeve to form a developing sleeve 4.
[0282]
<Development sleeve comparative production example 1>
As the developing sleeve, the surface of a stainless steel cylindrical tube having an outer diameter of 20 mm and a wall thickness of 0.8 mm was polished so that the cylindrical tube had a runout of 10 μm or less and a surface roughness of 4 μm or less in Rz notation. The end is masked and 3.92 × 10 3 by a blast machine using amorphous alumina abrasive grains (# 300). ^-2 The blast processing was performed at a blast pressure of MPa (4.0 kgf / cm). The masking width at both ends of the sleeve was set to 3 mm. The surface roughness Ra of the blasting sleeve was 1.12 μm on average at six points. A magnet was inserted into this sleeve, and flanges were attached to both ends to form a developing sleeve 3.
[0283]
[Example 1]
・ Binder resin A 100 parts by mass
・ 90 parts by mass of magnetite
(Octahedron, average particle size 0.22 μm, BET = 7.9 m ² / G,
Silicon content 0.35 wt%, σs = 84.5 Am ² / Kg,
σr = 10.9Am ² / Kg)
・ 4 parts by mass of low molecular weight polypropylene wax (melting point 130 ° C)
-Example compound (8) of imidazole derivative (2 parts by mass)
[0284]
The above materials were premixed well with a Henschel mixer and then melt kneaded with a twin screw extruder set at 140 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized material was further classified by an air classifier to obtain a weight average particle A classified fine powder having a diameter of 8.5 μm was obtained.
[0285]
100 parts by mass of the obtained classified fine powder was mixed with a silica fine powder (BET specific surface area 200 m ² / G) 0.8 parts by mass of hydrophobic silica treated with 17 parts by mass of an amino-modified silicone oil (amine equivalent: 830, viscosity 70 cSt at 25 ° C. 70 cSt) per 100 parts by mass, mixed with a Henschel mixer, and meshed with a mesh of 150 μm. To obtain a positively chargeable one-component magnetic toner 1.
[0286]
The following evaluation tests were performed on the obtained toner 1.
[0287]
Offset resistance evaluation test:
The fixing device of a commercially available copying machine NP6030 (manufactured by Canon Inc.) was removed to the outside, it was operated outside the copying machine, the fixing roller temperature could be set arbitrarily, and the process speed was changed to 100 mm / sec. Offset resistance was evaluated by passing an unfixed image through an external fixing device. At the time of evaluation, the temperature of the fixing roller was set to 230 ° C., the state of offset was observed, and the images were classified into the following ranks (evaluation environment: normal temperature / normal humidity (23 ° C./60% RH)).
[0288]
Offset rank
◎ (Excellent) No offset was seen at all.
○ (Good) Very slight offset is observed.
× (not possible) Offset occurs.
[0289]
Sleeve coatability evaluation test:
The toner coat on the sleeve was visually observed and the blotting generation level was classified into the ranks shown below (evaluation environment: normal temperature / normal humidity (23 ° C./60% RH), normal temperature / low humidity (23 ° C./5% RH), High temperature / humidity (32.5 ° C / 80% RH)).
[0290]
Blotch rank
◎ (Excellent) Not generated at all.
○ (Good) Slightly generated at the end of the sleeve.
Δ (OK): Very slight occurrence but no effect on image.
× (impossible) It is clearly generated and affects the image.
[0291]
Image evaluation test:
Using a commercially available copying machine NP6030 (manufactured by Canon Inc.), the developing sleeve was replaced with the developing sleeve 1 shown in the developing sleeve manufacturing example 1 of the present invention, and 10,000 copies were made in a normal temperature / humidity environment. The image density and fog were evaluated by copying 10,000 sheets in each of the following environments: low temperature environment / high humidity environment, normal temperature / low humidity environment (23 ° C./60% RH). 23 ° C./5% RH), high temperature / high humidity (32.5 ° C./80% RH)).
[0292]
Also, after copying 10000 sheets under normal temperature / humidity environment, a part of the developing sleeve surface was wiped off with ethanol, a solid black image was printed, and the image density before and after wiping with ethanol was measured. The sleeve contamination is evaluated by the calculation, and the smaller the density difference, the better the contamination suppression.
[0293]
The image density was measured using a “Macbeth reflection densitometer” (manufactured by Macbeth). The fog is measured using a "reflection densitometer" (manufactured by Tokyo Denshoku Technology Center Co., Ltd.) to measure the reflection density of the transfer paper and the reflection density of the transfer paper after the solid white copy, and the difference is used as the fog value. The smaller the numerical value, the better the fog suppression.
[0294]
Tables 1 and 2 summarize the evaluation results of these offset resistance test, sleeve coat property test, and image evaluation test.
[0295]
[Example 2]
A classified fine powder and a toner 2 were obtained in the same manner as in Example 1 except that the binder resin A was changed to the binder resin B. This toner 2 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0296]
[Example 3]
A classified fine powder and toner 3 were obtained in the same manner as in Example 1 except that binder resin A was changed to binder resin C. This toner 3 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0297]
[Example 4]
A classified fine powder and a toner 4 were obtained in the same manner as in Example 1 except that the binder resin A was changed to the binder resin D. This toner 4 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0298]
[Example 5]
A classified fine powder and a toner 5 were obtained in the same manner as in Example 1 except that the binder resin A was changed to the binder resin E. This toner 5 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0299]
[Comparative Example 1]
A classified fine powder and a toner 6 were obtained in the same manner as in Example 1 except that the binder resin A was changed to the binder resin F. This toner 6 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0300]
[Comparative Example 2]
A classified fine powder and a toner 7 were obtained in the same manner as in Example 1 except that the binder resin A was changed to the binder resin G. This toner 7 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0301]
[Example 6]
A classified fine powder and toner 8 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (1). This toner 8 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0302]
[Example 7]
A classified fine powder and toner 9 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (3). This toner 9 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0303]
Example 8
A classified fine powder and toner 10 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (4). This toner 10 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0304]
[Example 9]
A classified fine powder and toner 11 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (10). This toner 11 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0305]
[Example 10]
A classified fine powder and toner 12 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (11). This toner 12 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0306]
[Example 11]
A classified fine powder and toner 13 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to Compound Example (14). This toner 13 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0307]
[Comparative Example 3]
A classified fine powder and toner 14 were obtained in the same manner as in Example 1 except that Compound Example (8) of the imidazole derivative was changed to a nigrosine dye. This toner 14 was evaluated in the same manner as in Example 1. The evaluation results are summarized in Tables 1 and 2.
[0308]
[Example 12]
In Example 1, each evaluation other than the offset resistance test was performed in the same manner as in Example 1 except that the developing sleeve 1 was changed to the developing sleeve 2. The evaluation results are summarized in Tables 1 and 2.
[0309]
[Comparative Example 4]
In Example 1, each evaluation other than the offset resistance test was performed in the same manner as in Example 1 except that the developing sleeve 1 was changed to the developing sleeve 3. The evaluation results are summarized in Tables 1 and 2.
[0310]
[Table 1]

[0311]
[Table 2]

[0312]
Example 13
・ Binder resin A 100 parts by mass
・ 3.5 parts by mass of copper phthalocyanine
・ 3 parts by mass of low molecular weight polypropylene wax (melting point 130 ° C)
-Example of compound of imidazole derivative (18) 2 parts by mass
[0313]
The above materials were premixed well with a Henschel mixer and then melt kneaded with a twin screw extruder set at 120 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized material was further classified by an air classifier to obtain a weight average particle size. A classified fine powder having a diameter of 9.1 μm was obtained.
[0314]
100 parts by mass of the obtained classified fine powder was mixed with a silica fine powder (BET specific surface area 200 m ² / G) 0.8 parts by mass of hydrophobic silica treated with 17 parts by mass of an amino-modified silicone oil (amine equivalent: 830, viscosity at 25 ° C: 70 cSt) per 100 parts by mass, mixed with a Henschel mixer, and meshed to 150 μm mesh To obtain a positively chargeable non-magnetic one-component toner.
[0315]
Using a commercially available copying machine FC-330 (manufactured by Canon Inc.), the developing sleeve was replaced with the developing sleeve 4 of the present invention, and 1000 copies were made in a normal temperature / normal humidity environment. 1000 copies were made in each environment of high humidity environment, and image density and fog were evaluated in the same manner as in Example 1 (evaluation environment: normal temperature / normal humidity (23 ° C./60% RH), normal temperature / low humidity (23 ° C / 5% RH), high temperature / high humidity (32.5 ° C / 80% RH)).
[0316]
After 1000 copies were made under normal temperature / humidity environment, a part of the developing sleeve surface was wiped clean with ethanol, and sleeve contamination was evaluated in the same manner as in Example 1.
[0317]
As a result, a clear blue image having an image density of 1.20 to 1.30 and fog of 0.3 to 0.8 was obtained in each environment. There was no problem with sleeve contamination less than Δ0.02, and no offset occurred.
[0318]
【The invention's effect】
According to the image forming method of the present invention, in a positive toner having an acid value, by using the specific imidazole derivative shown in the present invention as a charge control agent, offset resistance can be achieved without impairing the charging characteristics and developing characteristics of the toner. The use of a developer support having a resin layer formed on a metal substrate as a developer carrier can greatly improve the charge-imparting ability and improve the development characteristics. It is possible to stably provide a high-definition image free from image density reduction and fog.
[Brief description of the drawings]
FIG. 1 is a schematic view of a cross section of a part of a developer carrier of the present invention.
FIG. 2 is a schematic view of a cross section of a part of the developer carrier of the present invention ((A) is before polishing, and (B) is after polishing).
FIG. 3 is a schematic diagram showing an example of a magnetic developer supply system developing device (using a magnetic blade as a regulating member) in which the developer carrying member of the present invention is incorporated.
FIG. 4 is a schematic view showing another example of a magnetic developer supply system developing device in which a developer carrying member of the present invention is incorporated (an elastic blade is used as a regulating member).
FIG. 5 is a schematic diagram for explaining the image forming method of the present invention.
[Explanation of symbols]
1 Coating layer (resin layer)
2 Conductive substances
3 filler
4 Binder resin
5 Solid lubricant
6. Cylindrical substrate
7. Photosensitive drum (latent image holder)
8 Regulation blade
9 Hopper
10 Toner
11 magnet
12 Cylindrical substrate
13 Coating layer (resin layer)
14 Developing sleeve (developer carrier)
15 Power supply
17 Elastic blade
A Rotating direction of developing sleeve
B Rotation direction of photosensitive drum
D Developing unit
501 Coating layer (resin layer)
502 Solid lubricant
503 conductive material
504 filler
505 binder resin
506 cylindrical substrate
801 Latent image carrier
801a Photoconductive layer
801b conductive base layer
802 charging roller
802a conductive elastic layer
802b Core
803 charging bias power supply
804 image exposure
805 Development roller
806 transfer roller
806a conductive elastic layer
806b Core
807 Transfer bias power supply
808 Transfer material
809 Cleaning device
810 Static elimination exposure device
811 heating and pressurizing means
813 Development bias power supply

Claims (5)

A positively chargeable toner containing at least a binder resin for a toner, a colorant, and a charge control agent is transported by a developer carrier having a resin layer formed on a metal substrate, and is formed on an electrostatic latent image holder. An electrostatic latent image is developed by transferring a positively chargeable toner from a developer carrying member to an image forming method for forming a toner image.
The acid value of the entire polymer component of the binder resin for toner is 0.5 mgKOH / g or more and 50 mgKOH / g or less;
The charge control agent is an imidazole derivative compound, the imidazole derivative compound has a condensate of imidazole or a derivative thereof and an aldehyde, and the condensate is a cyclic condensate or a cyclic condensate and a chain condensate. An image forming method characterized by comprising a mixture of: 2. The image forming method according to claim 1, wherein the imidazole derivative compound contains at least two kinds of condensates having different numbers of units. The said imidazole derivative compound contains at least 2 or more types of condensates having different numbers of units, and each of the condensates having different numbers of units is a mixture of a cyclic condensate and a chain condensate. Or the image forming method according to 2. 4. The condensate comprises a unit selected from the group consisting of units represented by the following general formulas (I), (II), (III) and (IV). 2. The image forming method according to 1.,

[Wherein, R ₁ and R ₃ represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent or a substituent And R ₂ represents a hydrogen atom, an alkyl group optionally having a substituent, an aryl group optionally having a substituent, or an optionally substituted group. R ₄ represents a hydrogen atom or a hydroxy group; an aralkyl group, an alicyclic group which may have a substituent, an alkyl group having a hydroxy group or an aralkyl group having a hydroxy group; ) And (IV) represent terminal units of the chain condensate. ] 5. The image forming method according to claim 1, wherein the acid value of the entire polymer component of the binder resin for the toner is 0.5 mgKOH / g or more and 30 mgKOH / g or less.

Images