JP2004217788A - Dispersion of colored fine particle and aqueous ink containing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion of colored fine particles having a good solvent resistance, dispersion stability and storability and an aqueous ink or an inkjet ink excellent in jetting stability, color reproducibility, light resistance of an image by using the dispersion of colored fine particles. <P>SOLUTION: The dispersion of colored fine particles comprises mixing and dispersing coloring materials and resins in an aqueous medium. At least one resin contained has at least one crosslinking structure selected from the bonds as expressed in formulae (1) and (2). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３５】
ここで、Ｒ′はやはりポリマー残基を表し、Ｒ″は反応性のオキサゾリン基に連結した架橋剤のポリマー残基を表す。ポリマー残基中のオキサゾリン基があると別のカルボキシル基と反応することで架橋を形成する。オキサゾリン基は特に反応性を妨げない限り置換されていてもよい。
【００３６】
また、前記式（２）で表されるヒドラゾン結合による架橋も前記ウレタン結合による架橋に比べ、粒子間の架橋また、水性媒体中の水との反応が少なく着色微粒子内での架橋が効果的に形成される点好ましい。ヒドラゾン結合の形成には、例えば、活性な水素を有する以下の、ヒドラジド系架橋剤
Ｈ_２ＮＨＮＣＯ−Ｒ″−ＣＯＮＨＮＨ_２
が好ましい架橋を形成する化合物の例としてあげられる。
【００３７】
ここでＲ″はアルキレン或いはアリーレン等の２価の基を表す、またこれらの基は特に架橋剤としての性質を損なわない限りは置換基を有していてもよい。
【００３８】
これらの例としては協和発酵製アジピン酸ヒドラジド（ＡＤＨ）、イソフタル酸ジヒドラジド（ＩＤＨ）等があげられ、例えばこれを用い、一方、ポリマーとして、このような活性な水素と反応することのできる、カルボニル基の様な官能基を有するモノマー成分（例えばダイアセトンアクリルアマイド；協和発酵製）を共重合成分として有するアクリル系共重合体ポリマーを着色微粒子分散体を形成する際の樹脂（ポリマー）として用いることで、ヒドラゾン結合による架橋を形成できる。
【００３９】
【化３】

【００４０】
ヒドラゾン結合は、要は、活性な水素とこれと反応する官能基との反応によるもので、これら活性水素あるいは官能基が樹脂中あるいは架橋剤中のどちらにあってもよい。上記の架橋反応は着色微粒子水性分散体の粒子周辺の水等の存在にも関わらず、粒子内で効率よく架橋を形成し、用いたポリマー樹脂の分子量を、確実に増大させることが出来る。またイソシアネートおよび、活性水素化合物であるアミン等の反応による架橋と異なり、反応の場が、粒子内に限られるためか、粒子間架橋が少なく凝集等も起こりにくい。
【００４１】
従ってこのような架橋結合を形成することは、インクジェット等、本発明に用いられる１０ｎｍ〜１００ｎｍの範囲の粒径を有する着色ポリマー樹脂微粒子の分子量を増大させ、耐溶剤性を改善するために好ましいものである。
【００４２】
本発明においては、着色微粒子を構成する樹脂（ポリマー）は、各種用いることが可能であるが、該ポリマーのＴｇは、少なくとも１種以上はＴｇが１０℃以上であるものを用いる方が好ましい。
【００４３】
本発明において使用可能な樹脂（ポリマー）は、前記のオキサゾリル基を有する化合物を架橋剤として用いる場合、また、ヒドラゾン結合を形成する場合、それぞれカルボキシル基（または、酸無水物基のように加水分解してカルボキシル基を形成する基でもよい）、または、活性なカルボニル基を有する基を樹脂中に有することが必要である。
【００４４】
色材との相溶性をあげるため、例えば、無水マレイン酸等の酸無水物基を有するモノマー成分を有するポリマーと色材を混合し、溶解分散した後或いは分散時に、加水分解してカルボキシル基を形成させることが好ましい場合がある。
【００４５】
また、自己乳化性を有する樹脂が分散体の分散安定性をあげる上では好ましいことから、水酸基や前記カルボキシル基或いは少量のスルホン酸基、リン酸基等のイオン性基、また、四級アンモニウム基、１，２級アミノ基を含有するポリマーが好ましいが、それぞれの構成成分となるモノマーが入手可能であることから、これらの官能基を有するポリマーはそれぞれの重合性ビニルモノマーを常法に従いラジカル共重合させ合成するのが好ましい。
【００４６】
共重合体を形成する好ましい共重合ビニルモノマーの具体例としては、例えば、酢酸ビニル、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチル、アクリル酸ｔ−ブチル、アクリル酸イソノニル、アクリル酸ドデシル、アクリル酸オクタデシル、２−フェノキシエチルアクリレート、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸２−エチルヘキシル、メタクリル酸ドデシル、メタクリル酸オクタデシル、メタクリル酸シクロヘキシル、メタクリル酸ステアリル、メタクリル酸ベンジル、メタクリル酸〔２−アセトアセトキシエチル〕、トリエチレングリコールメタクリレート、エトキシトリエチレングリコールメタクリレート、メタクリル酸グリシジル、メタクリル酸フェニル、ダイアセトンアクリルアミド（ＤＡＡＭ）、スチレン、α−メチルスチレン、マレイン酸、アクリロニトリル等のビニルモノマーが挙げられる。
【００４７】
本発明に係わる樹脂（ポリマー）として用いられる前記ビニル重合性モノマーの共重合体ポリマーは、ヒドロキシル基を有するモノマーを４０質量％以下、さらに好ましくは２５％以下、また、カルボキシル基を有するモノマー、また、スルホン酸基、燐酸基、４級アンモニウム基、１，２級アミノ基等の親水性基を有するモノマー、例えば２−アクリルアミド−２−メチルプロパンスルホン酸、メタクリル酸ジエチルアミノエチル等のモノマーであれば２０質量％以下好ましくは、１０質量％以下の比率で用いることが安定な電気二重層を形成し分散安定性が向上すること、また色材との親和性からみて好ましい。
【００４８】
また、前記オキサゾリル基を有する架橋剤と反応させるためにはカルボキシル基は０．３〜２０質量％の範囲で、好ましくは０．５〜１５質量％の範囲で含有する必要がある。あまり多くなると、色材との親和性が損なわれ、好ましくない。
【００４９】
ヒドラゾン結合の形成には、樹脂（ポリマー）中に、ヒドラジドと反応のために、前記ビニル重合性モノマーの共重合成分としてメタクリル酸〔２−アセトアセトキシエチル〕、ダイアセトンアクリルアミド（ＤＡＡＭ）等の活性なカルボニル基を有するモノマーをやはり０．３〜２０質量％以下、好ましくは０．５〜１５質量％以下含有させたポリマーを用いる。これもあまり多いと前記同様に色材との相溶性等に影響が出る。
【００５０】
これら重合性ビニルモノマーを公知の手法を用い、ラジカル共重合させることによって、本発明に係わる、未架橋のポリマー樹脂が得られる。
【００５１】
また、本発明においては、前記の共重合ポリマー樹脂中に、下記一般式（１）で表される構造を有する樹脂を同時に含有していることが好ましい。このような樹脂を前記の樹脂と共に含有させてもよいが、このような基を有するビニル重合性モノマーが上市されており、前記共重合体ポリマーの成分としてこのような基を有するビニル重合性モノマーを含有させることが好ましい。これらの構造をポリマーに導入することで、粒子間で起こる架橋反応をより抑制出来る。
【００５２】
一般式（１）
−（ＥＯ）_ｍ−（ＰＯ）_ｎ−Ｒ
ここにおいて、ＥＯはエチレンオキサイド基、ＰＯはプロピレンオキサイド基を表し、それぞれランダム或いはブロック共重合している。ＥＯまたはＰＯで表されるこれらのエチレンオキサイド基、プロピレンオキサイド基は更に置換されていてもよい。ｍ、ｎはそれぞれ０〜５００までの整数であり、２≦ｍ＋ｎ≦５００、Ｒは水素原子、ヒドロキシル基またはアルキル基、アリール基またはヘテロ環基等の置換基を表す。好ましいアルキル基としては、メチル、エチル、ブチル等炭素数１〜２２までの直鎖、或いは分岐のアルキル基、またやはり炭素数１〜２２までのシクロプロピル基、シクロペンチル基等の脂環式基であってもよい。これらはさらに他の置換基で置換されていてもよい。アリール基としては、フェニル基、ナフチル基等の基であり、やはり、活性な水素をもたない置換基で置換されていてもよい。また、ヘテロ環基としては、アジリジン、ピロリジン、フラン、チオフェン、ピロール、ピラゾール、イミダゾール、オキサゾール、チアゾール、ピリジン、ピリダジン等のヘテロ環基があげられ、これらに限定されないが、これらのヘテロ環基は、さらに置換基を有していてもよい。
【００５３】
また、これらのポリエチレンオキサイド基、ポリプロピレンオキサイド基の末端となる前記一般式（１）においてＲで表される基は、カルボキシル基あるいは活性カルボニル基等の架橋形成しうる官能基を含有しないものが好ましい。粒子間架橋が起こる可能性がある。
【００５４】
前記一般式（１）で表されるポリエチレンオキサイド基、ポリプロピレンオキサイド基を有するモノマー成分はポリマー成分中に１〜６０質量％、さらに好ましくは３〜５０質量％、好ましくは３〜４０質量％の割合で含有させることが好ましい。これらの基が立体的に表面を保護するためと考えられ、それにより粒子間で起こる架橋反応をより抑制出来、好ましい。多すぎる場合にはポリマー全体が親水性となり、染料との親和性が低下する、また相分離等を起こす等、安定な微粒子分散体の形成が妨げられ好ましくない。
【００５５】
前記一般式（１）で表されるポリエチレンオキサイド基、ポリプロピレンオキサイド基を有する重合性ビニルモノマーの具体的な例としては日本油脂製ブレンマーシリーズ、代表的には、ブレンマーＰＥシリーズ（ＰＥ−９０、ＰＥ−２００、ＰＥ−３５０）、ブレンマーＡＭＥシリーズ（ブレンマーＡＭＥ−４００等）、ブレンマーＰＭＥシリーズ、（ブレンマーＰＭＥ−１０００、ブレンマーＰＭＥ−４０００等）、ブレンマー５０ＰＯＥＰ−８００Ｂ、ブレンマー５５ＰＥＴシリーズ（ブレンマー５５ＰＥＴ８００等）がある。
【００５６】
前記架橋形成に必要な基を有するポリマー（好ましくはさらに、ポリエチレンオキサイド基、ポリプロピレンオキサイド基を有する）を色材と混合し、水系媒体中において乳化し、着色微粒子の水性分散体を調製し、分散時或いはその後、前記架橋形成のための架橋剤（例えば前記オキサゾリン化合物、またはヒドラジド化合物）と処理、反応させることによって、粒子内に前記架橋結合を形成する。
【００５７】
本発明において、樹脂として好ましいポリマーの例について、実施例中の合成例にいくつかの組成を示した。
【００５８】
また、前述のように本発明において色材および樹脂を混合し、水性媒体中おいて、乳化・分散して、その後、有機溶剤等を留去することで、着色微粒子分散体が得られる。着色微粒子分散体を形成する際には、必要であれば乳化剤を用いることが出来る。乳化の際にもちいることのできる乳化剤としては、通常のノニオン系乳化剤として、例えば、ポリオキシエチレンラウリルエーテル等のポリオキシエチレンオクアルキルエーテル類；例えば、ポリオキシエチレンノニルフェニルエーテル等のポリオキシエチレンアルキルフェニルエーテル類；ソルビタンモノラウレート等のソルビタン高級脂肪酸エステル類等、
またアニオン系乳化剤として、例えば、オレイン酸ナトリウム等の高級脂肪酸塩類；例えば、ドデシルベンゼンスルホン酸ナトリウム等のアルキルアリールスルホン酸塩類；例えば、ラウリル硫酸ナトリウム等のアルキル硫酸エステル塩類；例えば、ポリオキシエチレンラウリルエーテル硫酸ナトリウム等のポリオキシエチレンアルキルエーテル硫酸エステル塩類；ジオクチルスルホコハク酸ナトリウム、等のアルキルスルホコハク酸エステル塩及びその誘導体類等を用いることができる。
【００５９】
また、前記の乳化剤に代え、或いはそれに加え、重合可能な乳化剤（反応性乳化剤）を用いるのが好ましい。
【００６０】
反応性乳化剤としては、アニオン系及びノニオン系のいづれの乳化剤でも特に限定されず、例えば、（メタ）アリル基、（メタ）アクリル基、スチリル基などのラジカル重合性不飽和基を有する乳化剤が単独で又は２種類以上組み合わせて使用できる。
【００６１】
反応性乳化剤としては、アニオン系及びノニオン系のいづれの乳化剤でも特に限定されず、例えば、（メタ）アリル基、（メタ）アクリル基、スチリル基などのラジカル重合性不飽和基を有する乳化剤が単独で又は２種類以上組み合わせて使用できる。
【００６２】
このようなアニオン系反応性乳化剤としては、例えば、下記一般式（３）〜（６）で表される反応性乳化剤を挙げることができる。
【００６３】
【化４】

【００６４】
式中、Ｒ^２は水素、メチル基、Ｒ^３は炭素数６〜１８のアルキル基、アルケニル基、アリール基又はアラルキル基、Ｒ^４は水素又はメチル基、Ｒ^５は炭素数６〜１８のアルキル基、アルケニル基、アリール基又はアラルキル基、Ｘは単結合またはメチレン基、Ｍはアルカリ金属、ｍは１〜５０の自然数、ｎは１〜５０の自然数、ｑは０又は１である。
【００６５】
上記一般式（３）で表されるアニオン系反応性乳化剤の具体例としては、例えば、「アデカリアソープ ＳＥ−１０Ｎ」、「アデカリアソープ ＳＥ−２０Ｎ」、「アデカリアソープ ＳＥ−３０Ｎ」（以上、旭電化工業（株）製）が、上記一般式（４）で表されるアニオン系反応性乳化剤の具体例としては、例えば、「アクアロン ＨＳ−０５」、「アクアロン ＨＳ−１０」、「アクアロン ＨＳ−２０」、「アクアロン ＨＳ−３０」（以上、第一工業製薬（株）製）等が、また、上記一般式（５）のアニオン系反応性乳化剤の具体例としては、例えば「ラテムル Ｓ−１２０」、「ラテムル Ｓ−１２０Ａ」、「ラテムル Ｓ−１８０」、「ラテムル Ｓ−１８０Ａ」（以上、花王（株）製）、「エレミノールＪＳ−２１」（以上、三洋化成工業（株）製）等が、一般式（６）のアニオン系反応性乳化剤の具体例としては、例えば「アントックス ＭＳ−６０」（日本乳化剤（株）製）を挙げることができる。
【００６６】
その他、アニオン系反応性乳化剤としては、例えば「ラテムル ＡＳＫ」（花王（株）製）等のアルキルアルケニルコハク酸エステル塩系反応性乳化剤；例えば「エレミノール ＲＳ−３０」（三洋化成工業（株）製）等のポリオキシアルキレン（メタ）アクリレート硫酸エステル塩系反応性乳化剤；例えば「ＲＡ−１１２０」、「ＲＡ−２６１４」（以上、日本乳化剤（株）製）等のポリオキシアルキレンアルキルエーテル脂肪族不飽和ジカルボン酸エステル塩系反応性乳化剤；例えば「アントックス ＭＳ−２Ｎ」（日本乳化剤（株）製）等の（メタ）アクリル酸スルホアルキルエステル塩系反応性乳化剤；フタル酸ジヒドロキシアルキル（メタ）アクリレート硫酸エステル塩系反応性乳化剤；例えば「Ｈ−３３３０ＰＬ」（第一工業製薬（株）製）等のモノもしくはジ（グリセロール−１−アルキルフェニル−３−アリル−２−ポリオキシアルキレンエーテル）リン酸エステル塩系反応性乳化剤等が、また、ノニオン系反応乳化剤としては、例えば、下記一般式（７）及び（８）で示される反応性乳化剤を挙げることができる。
【００６７】
【化５】

【００６８】
式中、Ｒ^２は水素、メチル基、Ｒ^３は炭素数６〜１８のアルキル基、ｍは１〜５０の自然数、アルケニル基、アリール基又はアラルキル基、Ｒ^４は水素又はメチル基、Ｘは単結合またはメチレン基、Ｍはアルカリ金属である。
【００６９】
上記一般式（７）で表されるノニオン系反応性乳化剤の具体例としては、例えば「アデカリアソープＮＥ−１０」、「アデカリアソープＮＥ−２０」、「アデカリアソープＮＥ−３０」（以上、旭電化工業（株）製）等が、一般式（７）で表されるノニオン系反応性乳化剤の具体例としては、例えば「アクアロン ＲＮ−１０」、「アクアロン ＲＮ−２０」、「アクアロン ＲＮ−３０」、「アクアロン ＲＮ−５０」（以上、第一工業製薬（株）製）等が、またその他、例えば「ＲＭＡ−５６４」、「ＲＭＡ−５６８」（以上、日本乳化剤（株）製）等のポリオキシアルキレンアルキルフェニルエーテル（メタ）アクリレート系反応性乳化剤；例えば「ＲＭＡ−１１１４」（日本乳化剤（株）製）等のポリオキシアルキレンアルキルフェニルエーテル（メタ）アクリレート系反応性乳化剤等も挙げることができる。
【００７０】
これら反応性乳化剤の使用量は、ポリマーの合計１００質量部当たり、一般に０．１〜３０質量部、好ましくは２〜２５質量部、特に好ましくは３〜２０質量部の範囲で用いるのがよい。
【００７１】
これらの乳化剤は、粒子近傍に安定な電気二重層を形成すると同時に、樹脂との反応性を有するために、ポリエチレンオキサイド鎖、ポリプロピレンオキサイド鎖を、乳化時或いは乳化後に、樹脂中に導入でき、立体的に、後に、架橋を導入する際、粒子表面において粒子間架橋が防止でき好ましい。本発明において、このようにして樹脂中に、ポリエチレンオキサイド鎖、ポリプロピレンオキサイド鎖を導入してもよい。
【００７２】
次に、上記ポリマーとともに種粒子中に封入される色材について説明する。
該色材としては、上記ポリマーに溶解或いは分散可能な色材であれば特に制限無く用いることができ、例えば、油性染料、分散染料、直接染料、酸性染料及び塩基性染料等を挙げることができるが、良好な封入性の観点から油性染料及び分散染料を用いることが好ましい。上記分散染料として、特に好ましい具体例を以下に示すが、これのみに限定されるものではない。特に好ましい具体例としては、Ｃ．Ｉ．ディスパーズイエロー５、４２、５４、６４、７９、８２、８３、９３、９９、１００、１１９、１２２、１２４、１２６、１６０、１８４：１、１８６、１９８、１９９、２０４、２２４及び２３７；Ｃ．Ｉ．ディスパーズオレンジ１３、２９、３１：１、３３、４９、５４、５５、６６、７３、１１８、１１９及び１６３；Ｃ．Ｉ．ディスパーズレッド５４、６０、７２、７３、８６、８８、９１、９２、９３、１１１、１２６、１２７、１３４、１３５、１４３、１４５、１５２、１５３、１５４、１５９、１６４、１６７：１、１７７、１８１、２０４、２０６、２０７、２２１、２３９、２４０、２５８、２７７、２７８、２８３、３１１、３２３、３４３、３４８、３５６及び３６２；Ｃ．Ｉ．ディスパーズバイオレッド３３；Ｃ．Ｉ．ディスパーズブルー５６、６０、７３、８７、１１３、１２８、１４３、１４８、１５４、１５８、１６５、１６５：１、１６５：２、１７６、１８３、１８５、１９７、１９８、２０１、２１４、２２４、２２５、２５７、２６６、２６７、２８７、３５４、３５８、３６５及び３６８；並びにＣ．Ｉ．ディスパーズグリーン６：１及び９等が挙げられる。一方、上記油性染料としては、以下に限定されるものではないが、特に好ましい具体例としては、例えば、Ｃ．Ｉ．ソルベント・ブラック３、７、２７、２９及び３４；Ｃ．Ｉ．ソルベント・イエロー１４、１６、１９、２９、５６及び８２；Ｃ．Ｉ．ソルベント・レッド１、３、８、１８、２４、２７、４３、５１、７２、７３、１３２及び２１８；Ｃ．Ｉ．ソルベント・バイオレット３；Ｃ．Ｉ．ソルベント・ブルー２、１１及び７０；Ｃ．Ｉ．ソルベント・グリーン３及び７；並びにＣ．Ｉ．ソルベント・オレンジ２等が挙げられる。
【００７３】
また、水や各種有機溶剤に不溶な顔料をポリマー媒体中に分散して用いることも可能である。
【００７４】
本発明に使用できる顔料としては、従来公知の有機及び無機顔料が使用できる。例えばアゾレーキ、不溶性アゾ顔料、縮合アゾ顔料、キレートアゾ顔料等のアゾ顔料や、フタロシアニン顔料、ペリレン及びペリレン顔料、アントラキノン顔料、キナクリドン顔料、ジオキサンジン顔料、チオインジゴ顔料、イソインドリノン顔料、キノフタロニ顔料等の多環式顔料や、塩基性染料型レーキ、酸性染料型レーキ等の染料レーキや、ニトロ顔料、ニトロソ顔料、アニリンブラック、昼光蛍光顔料等の有機顔料、カーボンブラック等の無機顔料が挙げられる。
【００７５】
具体的な有機顔料を以下に例示する。
マゼンタまたはレッド用の顔料としては、Ｃ．Ｉ．ピグメントレッド２、Ｃ．Ｉ．ピグメントレッド３、Ｃ．Ｉ．ピグメントレッド５、Ｃ．Ｉ．ピグメントレッド６、Ｃ．Ｉ．ピグメントレッド７、Ｃ．Ｉ．ピグメントレッド１５、Ｃ．Ｉ．ピグメントレッド１６、Ｃ．Ｉ．ピグメントレッド４８：１、Ｃ．Ｉ．ピグメントレッド５３：１、Ｃ．Ｉ．ピグメントレッド５７：１、Ｃ．Ｉ．ピグメントレッド１２２、Ｃ．Ｉ．ピグメントレッド１２３、Ｃ．Ｉ．ピグメントレッド１３９、Ｃ．Ｉ．ピグメントレッド１４４、Ｃ．Ｉ．ピグメントレッド１４９、Ｃ．Ｉ．ピグメントレッド１６６、Ｃ．Ｉ．ピグメントレッド１７７、Ｃ．Ｉ．ピグメントレッド１７８、Ｃ．Ｉ．ピグメントレッド２２２等が挙げられる。
【００７６】
オレンジまたはイエロー用の顔料としては、Ｃ．Ｉ．ピグメントオレンジ３１、Ｃ．Ｉ．ピグメントオレンジ４３、Ｃ．Ｉ．ピグメントイエロー１２、Ｃ．Ｉ．ピグメントイエロー１３、Ｃ．Ｉ．ピグメントイエロー１４、Ｃ．Ｉ．ピグメントイエロー１５、Ｃ．Ｉ．ピグメントイエロー１７、Ｃ．Ｉ．ピグメントイエロー９３、Ｃ．Ｉ．ピグメントイエロー９４、Ｃ．Ｉ．ピグメントイエロー１３８等が挙げられる。
【００７７】
グリーンまたはシアン用の顔料としては、Ｃ．Ｉ．ピグメントブルー１５、Ｃ．Ｉ．ピグメントブルー１５：２、Ｃ．Ｉ．ピグメントブルー１５：３、Ｃ．Ｉ．ピグメントブルー１６、Ｃ．Ｉ．ピグメントブルー６０、Ｃ．Ｉ．ピグメントグリーン７等が挙げられる。
【００７８】
本発明のインクに使用する顔料分散体の平均粒径は１０〜２００ｎｍであることが好ましく、１０〜１５０ｎｍがより好ましく、１０〜１００ｎｍがさらに好ましい。顔料分散体の平均粒径が１５０ｎｍを越えると光沢メディアに記録した画像では光沢感の劣化が起こり、トランスペアレンシーメディアに記録した画像では著しい透明感の劣化が起こる。また、顔料分散体の平均粒径が１０ｎｍ未満になると顔料分散体の安定性が悪くなり易く、インクの保存安定性が劣化し易くなる。
【００７９】
顔料分散体の粒径測定は、光散乱法、電気泳動法、レーザードップラー法等を用いた市販の粒径測定機器により求めることができる。また、透過型電子顕微鏡による粒子像撮影を少なくとも１００粒子以上に対して行い、この像をＩｍａｇｅ−Ｐｒｏ（メディアサイバネティクス製）等の画像解析ソフトを用いて統計的処理を行うことによっても求めることが可能である。
【００８０】
色材として、あるいは、特開平９−２７７６９３号、特開平１０−２０５５９号、特開平１０−３００６１号に示されるような、金属錯体色素も使用可能である。たとえば、特開平１０−２０５５９号に記載の一般式（Ｉ）及び一般式（ＩＩ）で表される色素が使用可能である。
【００８１】
【化６】

【００８２】
一般式（Ｉ）において、Ｘ^１は、金属イオンと少なくとも２座の配位結合を形成可能な構造を有する原子の集まりを表し、Ｙ^１は芳香族炭化水素環、５員或いは６員の複素環又は−Ｌ^４＝Ｙ^２を表し、Ｙ^２は含窒素の５員或いは６員の複素環を表す。Ｌ^１、Ｌ^４は置換又は非置換のメチン基並びに窒素原子を表し、Ｌ^２、Ｌ^３は置換又は非置換のメチン基を表す。Ｍは金属イオンを表し、Ｘ^１で形成される原子の集まりと少なくとも２座の配位結合を形成している。ｍは０、１、２又は３の整数を表し、ｎ１は１、２又は３の整数を表す。又、一般式（ＩＩ）において、Ｘ^３、Ｙ^３、Ｍ及びｎ２はそれぞれ上記Ｘ^１、Ｙ^１、Ｍ及びｎ１と同義である。
【００８３】
さらにこれらの具体例として以下の色素が挙げられる。
【００８４】
【化７】

【００８５】
【化８】

【００８６】
【化９】

【００８７】
【化１０】

【００８８】
【化１１】

【００８９】
【化１２】

【００９０】
【化１３】

【００９１】
【化１４】

【００９２】
【化１５】

【００９３】
【化１６】

【００９４】
【化１７】

【００９５】
【化１８】

【００９６】
【化１９】

【００９７】
【化２０】

【００９８】
これらの色材および前記樹脂からなる着色微粒子の製造方法については、各種の乳化法で製造することができる。乳化法としては、各種の方法を用いることができる。それらの例は、例えば、「機能性乳化剤・乳化技術の進歩と応用展開 シー エム シー」の８６ページの記載にまとめられている。本発明においては、特に、超音波、高速回転せん断、高圧による乳化分散装置を使用することが好ましい。
【００９９】
超音波による乳化分散では、いわゆるバッチ式と連続式の２通りが使用可能である。バッチ式は、比較的少量のサンプル作製に適し、連続式は大量のサンプル作製に適する。連続式では、たとえば、ＵＨ−６００ＳＲ（株式会社エスエムテー製）のような装置を用いることが可能である。このような連続式の場合、超音波の照射時間は、分散室容積／流速×循環回数で求めることができる。超音波照射装置が複数ある場合は、それぞれの照射時間の合計としてもとめられる。超音波の照射時間は実際上は１００００秒以下である。また、１００００秒以上必要であると、工程の負荷が大きく、実際上は乳化剤の再選択などにより乳化分散時間を短くする必要がある。そのため１００００秒以上は必要でない。さらに好ましくは、１０秒以上、２０００秒以内である。
【０１００】
高速回転せん断による乳化分散装置としては、「機能性乳化剤・乳化技術の進歩と応用展開 シー エム シー」の２５５〜２５６ページに記載されているような、ディスパーミキサーや、２５１ページに記載されているようなホモミキサー、２５６ページに記載されているようなウルトラミキサーなどが使用できる。これらの型式は、乳化分散時の液粘度によって使い分けることができる。これらの高速回転せん断による乳化分散機では、攪拌翼の回転数が重要である。ステーターを有する装置の場合、攪拌翼とステーターとのクリアランスは通常０．５ｍｍ程度で、極端に狭くはできないので、せん断力は主として攪拌翼の周速に依存する。周速が５ｍ／Ｓ以上１５０ｍ／Ｓ以内であれば本発明の乳化・分散に使用できる。周速が遅い場合、乳化時間を延ばしても小粒径化が達成できない場合が多く、１５０ｍ／Ｓにするにはモーターの性能を極端に上げる必要があるからである。さらに好ましくは、２０〜１００ｍ／ｓである。
【０１０１】
高圧による乳化分散では、ＬＡＢ２０００（エスエムテー社製）などが使用できるが、その乳化・分散能力は、試料にかけられる圧力に依存する。圧力は１０^４ｋＰａ〜５×１０^５ｋＰａの範囲が好ましい。また、必要に応じて数回乳化・分散を行い、目的の粒径を得ることができる。圧力が低すぎる場合、何度乳化分散を行っても目的の粒径は達成できない場合が多く、また、圧力を５×１０^５ｋＰａにするためには、装置に大きな負荷がかかり実用的ではない。さらに好ましくは５×１０^４ｋＰａ〜２×１０^５ｋＰａの範囲である。
【０１０２】
これらの乳化・分散装置は単独で用いてもよいが、必要に応じて組み合わせて使用することが可能である。コロイドミルや、フロージェットミキサなども単独では本発明の目的を達成できないが、本発明の装置との組み合わせにより、短時間で乳化・分散を可能にするなど本発明の効果を高めることが可能である。
【０１０３】
本発明においては、前記油溶性染料を、前記ポリエチレンオキサイド基またはポリプロピレンオキサイド基、およびイソシアネート基等の架橋性基を有する共重合ポリマー樹脂と共に、酢酸エチル等の有機溶剤に溶解・混合した後、前記分散装置により乳化・分散し、溶剤を除去して水性の分散体を形成した後、架橋剤として例えば、前記３−アミノプロパノール等のアミン化合物を、乳化、分散した水性分散体に混合して架橋させる。反応を促進するために、例えば、必要な場合には水性分散体を４０〜９０℃の範囲で加温し、十分な時間（形成される架橋結合によって異なるが、例えば、数分から必要な場合には数時間をかけて）反応させ、微粒子内部での架橋反応を十分行わせることも好ましい。
【０１０４】
また、反応が比較的ゆっくりである場合には、これら架橋剤は、ポリマー、染料と共に混合溶解して、その後乳化、分散するという方法でもよい。
【０１０５】
ここにおいて水性分散体とは水を主体とする水系の媒体中に前記着色微粒子が分散しているものをいい、例えば非水溶性、或いは水溶性の有機溶媒が混合されていてもよいが、水を主体とする水系の媒体とは、媒体中での水の割合が５０％以上のものをいい、水性インクの水性も同じ意味である。
【０１０６】
また、前記本発明に係わる、前記のポリマー、色材等を溶解分散する有機溶剤としては、低沸点（例えば１５０℃以下、好ましくは１００℃以下）の有機溶剤が好ましく、具体例としては、酢酸エチル、酢酸ブチル、メチルエチルケトン、ブタノール、シクロヘキサノン等の溶剤を好ましく用いることができる。
【０１０７】
本発明に係わる着色微粒子分散体は、このようにして形成した色材および樹脂（ポリマー）を含有する着色微粒子散体を種粒子として、これに重合可能な素材を添加、重合させ、更に、コアシェル構造としてもよい。
【０１０８】
重合可能な素材を添加して、種粒子上でシード重合させる方法としては、色材と樹脂を含有する着色微粒子の分散体を形成した後、重合可能な素材として重合性不飽和二重結合を有するモノマーを添加し活性剤の存在下、乳化重合を行って、重合と同時に種粒子となる着色微粒子表面に沈着させる方法が本発明においては好ましい。この方法で形成した場合、好ましい場合には、後添加した重合性不飽和二重結合を有するモノマーは、前記種粒子上で重合してポリマーシェルを形成する。
【０１０９】
色材と樹脂からなる着色微粒子を種粒子として、これに後添加して、種粒子上で重合させる重合性不飽和二重結合を有するモノマーとしては、エチレン、プロピレン、ブタジエン、塩化ビニル、塩化ビニリデン、酢酸ビニル、スチレン、（メタ）アクリル酸エステル類、（メタ）アクリル酸等、アクリルアミド類等から選ばれる化合物、特スチレンや（メタ）アクリル酸エチル、（メタ）アクリル酸ブチル、（メタ）アクリル酸エチルヘキシル等の（メタ）アクリル酸エステル類等が好ましいが、これらのモノマーに加えて、分子内にヒドロキシル基を含有する重合性不飽和二重結合を有するモノマー、例えば、ヒドロキシエチル（メタ）アクリレート等のヒドロキシアルキル（メタ）アクリレート、或いはヒドロキシル基を有する重合性不飽和二重結合を有するモノマーを、後添加する原料モノマー全体の中で、最大５０％、その他のエチレン性不飽和二重結合を有するモノマーと混合して用い共重合させることが好ましい。
【０１１０】
このような共重合体として、例えば、スチレン／メタクリル酸２−ヒドロキシエチル、スチレン／アクリル酸２−ヒドロキシエチル等が好ましい例としてあげられる。
【０１１１】
また、シェルの安定性を増す等の理由から、アクリル酸、メタクリル酸等のカルボン酸を含有するモノマー或いはスルホン酸を含有するモノマー等、ｐＫａ値で３〜７の解離性基を含有するエチレン性不飽和モノマーを共重合成分の１０％以下用いてもよい。これらのモノマー成分をシェル形成に用いることによって、当該コア／シェル着色微粒子の水分散体の安定性が向上する。
【０１１２】
本発明においては、シェルに用いられるポリマー量が総ポリマー量の５質量％以上９５質量％以下である。５質量％より少ないとシェルの厚みが不十分で、色材を多く含有するコアの一部が粒子表面に現れ易くなる。また、シェルのポリマーが多すぎると、コアの色材保護能低下を起こし易い。さらに好ましくは１０質量％以上９０質量％以下である。
【０１１３】
色材の総量は総ポリマー量に対して２０質量％以上１０００質量％以下であることが好ましい。色材量がポリマーに比して少なすぎると吐出後の画像濃度が上がらず、また、色材質量が多すぎるとポリマーの保護能が十分に得られない。
【０１１４】
このようにして形成された本発明に係わる着色微粒子分散体の着色微粒子の体積換算平均粒径は１０〜１５０ｎｍ、好ましくは１０〜１００ｎｍであり、この粒径範囲において安定であるため、鮮やかな色を有すると同時に、インクとしたときの安定性に優れる。
【０１１５】
また、体積平均粒径の変動係数が８０％以下である分散体が好ましく経時での粒径変動も少ない。
【０１１６】
体積平均粒子径は、透過型電子顕微鏡（ＴＥＭ）写真の投影面積（少なくとも１００粒子以上に対して求める）の平均値から得られた円換算平均粒径を、球形換算して求めた。また、体積平均粒径とその標準偏差を求め、標準偏差を体積平均粒径で割ることで変動係数を求めた。或いは、動的光散乱法を利用して変動係数を求めることも出来る。例えば、大塚電子製レーザー粒径解析システムや、マルバーン社製、ゼータサイザーを用いて求める事が出来る。
【０１１７】
粒径の変動係数は、粒径の標準偏差を粒径で割った値であるが、この値が大きいほど粒径の分布が広い事を意味する。体積平均粒径の変動係数が８０％以上であると、粒径分布が非常に広くなり、粒子間の表面物性にばらつきが生じ、これにより粒子の凝集を招きやすい。また、粒子の凝集はメディア上で、色材の光散乱を招き易く、画質の低下も招き易くする。
【０１１８】
この様にして形成された、本発明にかわる着色微粒子分散体は、トータルのポリマー量として本発明のポリマーエマルジョン型水性インク中にポリマーが０．５〜５０質量％配合されることが好ましく、０．５〜３０質量％配合されることが更に好ましい。上記ポリマーの配合量が０．５質量％に満たないと、色材の保護能が十分でなく、５０質量％を超えると、サスペンションのインクとしての保存安定性が低下したり、ノズル先端部でのインク蒸発に伴うインクの増粘やサスペンションの凝集が起こることによってプリンタヘッドの目詰りが起こる場合があるので、上記範囲内とすることが好ましい。
【０１１９】
一方、上記色材は、該インク中に１〜３０質量％配合されることが好ましく、１．５〜２５質量％配合されることが更に好ましい。上記色材の配合量が１質量％に満たないと印字濃度が不十分であり、３０質量％を超えるとエマルジョンの経時安定性が低下し、凝集等による粒径増大の傾向があるので、上記範囲内とすることが好ましい。
【０１２０】
本発明の水性インクは、水を主体とする水性媒体とし、上記色材を封入したポリマーのエマルジョンからなり、該エマルジョンには従来公知の各種添加剤、例えば多価アルコール類のような湿潤剤、分散剤、シリコーン系等の消泡剤、クロロメチルフェノール系等の防黴剤及び／又はＥＤＴＡ等のキレート剤、又、亜硫酸塩等の酸素吸収剤等が含有されていてもよい。
【０１２１】
本発明に係わる着色微粒子分散体は、内部が架橋されており、耐溶剤性が高いため、これらの添加剤のうち、各種の有機溶剤、特に多価アルコール類のような以下に示す湿潤剤（低表面張力を実現する効果がある）との共存下での安定性が高く、凝集を起こしにくい。
【０１２２】
湿潤剤としては、例えば、エチレングリコール、プロピレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、グリセリン、ジエチレングリコールジエチルエーテル、ジエチレングリコールモノｎ−ブチルエーテル、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、メチルカルビトール、エチルカルビトール、ブチルカルビトール、エチルカルビトールアセテート、ジエチルカルビトール、トリエチレングリコールモノメチルエーテル、トリエチレングリコールモノエチルエーテル、トリエチレングリコールモノブチルエーテル、プロピレングリコールモノメチルエーテル等、また、１，２−ヘキサンジオール等の多価アルコール及びそのエーテル、アセテート類、Ｎ−メチル−２−ピロリドン、１，３−ジメチルイミダゾリジノン、トリエタノールアミン、ホルムアミド、ジメチルホルムアミド等の含窒素化合物類、ジメチルサルフォキサイド等のような水溶性有機溶剤があげられる。これらの一種又は二種以上を湿潤剤として使用することができる。これらの湿潤剤の配合量に特に制限はないが、上記インク中に好ましくは０．１〜５０質量％配合することができ、更に好ましくは０．１〜３０質量％配合することができる。
【０１２３】
また、上記分散剤としては、特に制限されるものではないが、そのＨＬＢ値が８〜１８であることが、分散剤としての効果が発現し、サスペンションの粒径の増大抑制効果がある点から好ましい。
【０１２４】
分散剤として市販品も使用することができる。そのような市販品としては、例えば花王（株）製の分散剤デモールＳＮＢ，ＭＳ，Ｎ，ＳＳＬ，ＳＴ，Ｐ（商品名）が挙げられる。
【０１２５】
分散剤の配合量に特に制限はないが、本発明のインク中に、０．０１〜１０質量％配合されることが好ましい。該化合物の配合量が０．０１質量％に満たないとサスペンションの小粒径化が困難であり、１０質量％を超えるとエマルジョンの粒径が増大したりエマルジョン安定性が低下し、ゲル化するおそれがあり、上記範囲内とすることが好ましい。
【０１２６】
また、上記消泡剤としては、特に制限なく、市販品を使用することができる。そのような市販品としては、例えば信越シリコーン社製のＫＦ９６、６６、６９、ＫＳ６８、６０４、６０７Ａ、６０２、６０３、ＫＭ７３、７３Ａ、７３Ｅ、７２、７２Ａ、７２Ｃ、７２Ｆ、８２Ｆ、７０、７１、７５、８０、８３Ａ、８５、８９、９０、６８−１Ｆ、６８−２Ｆ（商品名）等が挙げられる。これら化合物の配合量に特に制限はないが、本発明のポリマーエマルジョン型水系インク中に、０．００１〜２質量％配合されることが好ましい。該化合物の配合量が０．００１質量％に満たないとインク調製時に泡が発生し易く、又、インク内での小泡の除去が難しく、２質量％を超えると泡の発生は抑えられるものの、印字の際、インク内でハジキが発生し印字品質の低下が起こる場合があるので、上記範囲内とすることが好ましい。
【０１２７】
本発明のインクジェット記録用水性インクを使用するインクジェットヘッドはオンデマンド方式でもコンティニュアス方式でも構わない。又吐出方式としては、電気−機械変換方式（例えば、シングルキャビティー型、ダブルキャビティー型、ベンダー型、ピストン型、シェアーモード型、シェアードウォール型等）、電気−熱変換方式（例えば、サーマルインクジェット型、バブルジェット（Ｒ）型等）等など何れの吐出方式を用いても構わない。
【０１２８】
本発明のインクジェット記録用水性インクを用いた画像形成においては、例えば、インクジェット記録用水性インクを装填したプリンター等により、デジタル信号に基づきインクジェットヘッドよりインクを液滴として吐出させインク受容体に付着させることで、例えばインクジェット画像記録媒体上にインクジェット記録画像が形成されたインクジェットプリントが得られる。
【０１２９】
インクジェット画像記録媒体としては、例えば、普通紙、コート紙、キャストコート紙、光沢紙、光沢フィルム、ＯＨＰフィルムのいずれも使用することができ、なかでも例えば多孔質層が形成されている所謂空隙層を有する被記録媒体であれば好ましい。上述した支持体の素材或いは形状に特に限定されるものではなく、例えばシート状に形成されたもの以外に立体的な構造を有するものであってもよい。
【０１３０】
本発明の水性インクは、インクジェット記録用のインクとして以外に、例えば、一般の万年筆、ボールペン、サインペン等の筆記具用のインクとしても使用可能である。本発明のサスペンションを乾燥し、微粒の粉体を得ることもできる。得られた粉体は、電子写真のトナーなどにも使用可能である。
【０１３１】
【実施例】
以下に、合成例、実施例を挙げて本発明を更に具体的に説明するが、本発明は、これら実施例の範囲に限定されるものではない。
【０１３２】
〈樹脂合成１〉
３リットルの四つ口フラスコに滴下装置、温度計、窒素ガス導入管、撹拌装置及び還流冷却管を付し、脱水したメチルエチルケトン２０ｇをしこみ、８０℃に加熱した。下記表１に示した組成割合のモノマーを総量が１００ｇとなるように秤量し、更にＮ，Ｎ′−アゾビスイソバレロニトリル２ｇを前記モノマーに加えた混合液を、フラスコ中に２時間かけて滴下し、同温度にて５時間反応させた。その後メチルエチルケトン８０ｇを添加し冷却、５０質量％のポリマー溶液を得た。ゲル化したポリマーはアセトン、酢酸エチルに不溶であった。（Ｒ−１〜Ｒ−１１）
【０１３３】
【表１】

【０１３４】
ブレンマーＰＭＥ−１０００：
−（ＥＯ）_ｍ−ＣＨ_３ （ｍ≒２３）を有するメタアクリレート
ブレンマーＰＰ−８００：
−（ＰＯ）_ｍ−Ｈ （ｍ≒１３）を有するメタアクリレート
ブレンマーＡＭＥ−４００：
−（ＥＯ）_ｍ−ＣＨ_３ （ｍ≒９）を有するアクリレート
ここにおいて、ＥＯ；−ＣＨ_２ＣＨ_２Ｏ−を、ＰＯ；−Ｃ_３Ｈ_６Ｏ−を表し、上記はすべて日本油脂製。
ＨＥＭＡ：メタクリル酸２−ヒドロキシエチル、ＳＴ：スチレン、ＭＭＡ：メタクリル酸メチル、ＳＭＡ：ステアリルメタクリレート、カレンズＭＯＩ：２−メタクリロイルオキシエチルイソシアネート（昭和電工製）、ブレンマーＧ：グリシジルメタクリレート、ＭＡＡ：メタアクリル酸、ＤＡＡＭ：ダイアセトンアクリルアミド（協和発酵製）
〈樹脂合成２〉
３リットルの四つ口フラスコに滴下装置、温度計、窒素ガス導入管、撹拌装置及び還流冷却管を付し、脱水したメチルエチルケトン２０ｇをしこみ、６０℃に加熱した。９．１ｇの２−ヒドロキシエチルアミノプロピルアミン（広栄化学製）、１０．９ｇのブレンマーＧを添加し、５時間反応させた後、１０ｇのＤＡＡＭ、４０ｇのＳＴ、３０ｇのブレンマーＰＭＥ−１０００、更にＮ，Ｎ′−アゾビスイソバレロニトリル２ｇを２時間かけて滴下し、８０℃に昇温させ６時間反応させた。その後メチルエチルケトン８０ｇを添加し冷却、ポリマー濃度５０質量％の１、２級アミン含有ポリマー溶液を得た。（Ｒ−１２）
〈着色微粒子の製造〉
（ヒドラゾン結合を有する染料着色微粒子分散体の製造）
クレアミックスＣＬＭ−０．８Ｓ（エムテクニック（株）社製）のポットに１２ｇのＣ．Ｉ．Ｓｏｌｖｅｎｔ Ｙｅｌｌｏｗ １６２（▲１▼染料）、及び１２０ｇの酢酸エチルを入れ、攪拌して染料を完全溶解させた。さらに表２に示すように、１２ｇの樹脂を含む液２４ｇを加え（▲２▼樹脂）、ラウリル硫酸ナトリウム（ＳＤＳ）またはＫＨ−０５（第一工業製）を含む水溶液２７０ｇを添加（▲３▼乳化剤）後、４０℃に温度を保ちながら回転数２００００ｒｐｍで５分間乳化した。有機溶剤を減圧除去した後、アジピン酸ジヒドラジド（Ａ１）ないしポリイソシアネート（Ｎ３３００、住化バイエルウレタン製）（Ａ２）を添加し、８０℃で１２０分架橋反応させた。着色微粒子分散体１〜７を作製した。
【０１３５】
【表２】

【０１３６】
（アミドエステル結合を有する染料着色微粒子分散体の製造）
前記着色微粒子分散体１の製法で、▲２▼として、Ｒ−７を１２ｇ含む液２４ｇを用い、乳化時の水相にカルボン酸と反応するオキサゾリン基を有する、エポクロスＫ−２０２０Ｅ（日本触媒製）４０％液を６ｇ添加し８０℃で５時間反応させ、他の架橋剤を添加しなかった以外は同様にして着色微粒子分散体８を得た（粒径８０ｎｍ、本発明）。また架橋剤を加えずに着色微粒子分散体９（粒径８０ｎｍ、比較例）を得た。
【０１３７】
また、着色微粒子分散体８を８０℃に保温して、ＭＭＡ３ｇと、過硫酸カリウム０．１ｇを含む水溶液３ｇをそれぞれ１時間かけて添加し、そのまま５時間反応させて、コアシェル構造を有する着色微粒子分散体１０を得た。
【０１３８】
〈耐溶剤性評価〉
着色微粒子分散体１〜１０各４ｇに対し、１，２−ペンタンジオールの１０質量％水溶液１ｇをゆっくり加え、良く攪拌した後、６０℃で１週間静置し、粒径の変化率を計算した。ここで粒径は体積平均粒径であり、前記のとおり、透過型電子顕微鏡（ＴＥＭ）、具体的には、日本電子（株）製ＪＥＭ−２０００ＦＸを用いて撮影した写真の投影面積（少なくとも１００粒子以上に対して求める）の平均値から得られた円換算平均粒径を、球形換算して求めた。また、体積平均粒径とその標準偏差を求め、標準偏差を体積平均粒径で割ることで変動係数を求めた。
【０１３９】
粒径の変化率：６０℃１週間後の粒径／即粒径
にて求めた。結果を表３に示す。
【０１４０】
【表３】

【０１４１】
本発明に係わる着色微粒子は粒径の変化率が小さく耐溶剤性がよいことがわかる。
【０１４２】
【発明の効果】
耐溶剤性が良好で、分散安定性、保存性のよいインクジェット用インクとして有用な着色微粒子分散体が得られた。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a colored fine particle dispersion suitable for use in an ink jet ink, a water-based ink using the colored fine particle dispersion, and an image forming method.
[0002]
[Prior art]
In recent years, recording materials and inking materials used in printers, printing presses, markers, writing instruments, and the like, particularly ink jet inks, mainly include aqueous solutions of water-soluble dyes and those mainly including fine dispersions of pigments. Used.
[0003]
Inks using water-soluble dyes have more vivid color reproducibility than pigment inks, but tend to bleed on recording paper because they are aqueous solutions of dyes. Also, since the apparent drying speed needs to be increased, the bleeding of the ink is large in order to increase the penetration into the recording paper, and it is a water-soluble dye and has poor water resistance. There is a problem that they are very low, and many attempts have been made to improve them, but it is hard to say that these drawbacks have been improved.
[0004]
On the other hand, an aqueous ink used as an aqueous dispersion by coloring a water-dispersible resin with an oil-soluble dye or a hydrophobic dye, that is, an aqueous ink using a colored polymer fine particle as a recording material, is used as the aqueous ink. It is expected as an alternative to the ink used, and various studies have been made on the composition of dyes and polymers, and the atomization and composition of colored fine particles.
[0005]
For example, JP-A-54-58504 proposes an oil-in-water dispersion of a mixture of a hydrophobic dye solution and vinyl polymer fine particles. The vinyl polymer fine particles are mixed with a hydrophobic dye solution, the polymer fine particles are swollen with a solvent of the dye solution, and colored with a dye. Since the hydrophobic dye serves as a recording material, the resulting image has water resistance. In this proposal, water is used as the continuous phase, and colored vinyl polymer particles swollen with a solvent are used as the disperse phase, so that the viscosity of the ink is given to water, and the solvent has a somewhat high viscosity (low volatility). Is allowed to be used.
[0006]
JP-A-55-139471, JP-A-3-250069, and JP-A-54-58504 also propose inks using emulsion-polymerized or dispersed-polymer particles dyed with a dye.
[0007]
Further, JP-A-2001-98194 discloses a method using a copolymer resin composed of a hydrophilic polymer chain and a hydrophobic polymer chain, and JP-A-2000-191968 discloses a vinyl polymer polymerizable unsaturated acid monomer, Japanese Patent Application Laid-Open No. Hei 9-157508 discloses a composition using a monomer containing styrene macromer and a composition using a polyester resin containing cyclohexene dicarboxylic acid.
[0008]
U.S. Pat. No. 6,384,108 discloses fine particles obtained by dissolving a self-emulsifying polymer together with a dye in a solvent and emulsifying and forming in an aqueous phase.
[0009]
However, any of these fine particles are used by mixing various aqueous organic solvents in the ink-jet ink.Therefore, the use of the colored fine particles formed by these methods in the ink-jet ink has a disadvantage that the solvent resistance is poor. Is a big problem. The fine particles described in the above-mentioned U.S. Patent No. 6,384,108 are self-emulsifying, so they have excellent dispersion stability and are finely divided to form preferable colored fine particles, but there is no subsequent shelling. The fact that the resin having a small molecular weight is used for atomization is considered to be the reason for poor solvent resistance.
[0010]
As an attempt to solve these problems of solvent resistance, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-121417) discloses surface-crosslinked core-shell particles. However, since the dye is dissolved and polymerized in the monomer, the polymerization inhibition effect of the dye is large, and the cross-linking between particles occurs when the particle surface is cross-linked to increase the molecular weight, and the particles are likely to aggregate. There is.
[0011]
On the other hand, Patent Document 2 (Japanese Patent Application Laid-Open No. Hei 8-218015) describes polymer particles having an ionic group and imparting self-emulsifiability and at the same time crosslinked by urethane bonds. By increasing the molecular weight by the introduction, the solvent resistance of the colored fine particles is improved. However, in the case of using a resin that has a large hydrophilic group that contributes to dispersion stability such as a hydroxyl group or a carboxyl group as a resin constituting the colored fine particles, in order to introduce a crosslink by a urethane bond, for example, a polyisocyanate or the like is used. The reaction between the crosslinking agent and these hydrophilic groups is difficult to use, and it is difficult to use, and as the particle size of the aqueous dispersion becomes finer, it becomes difficult to form crosslinks in the particles. Therefore, it is desired to introduce a crosslink other than a urethane bond into the polymer by using another crosslinker.
[0012]
[Patent Document 1]
JP 2002-121417 A
[0013]
[Patent Document 2]
JP-A-8-218015
[0014]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to obtain a colored fine particle dispersion having good solvent resistance, good dispersion stability, and good storage stability even when atomized, and using the colored fine particle dispersion, stable ejection is achieved. An object of the present invention is to obtain an aqueous ink or an ink jet ink having good properties, color reproducibility and light fastness of an image.
[0015]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
[0016]
1. A colored fine particle dispersion obtained by mixing a coloring material and a resin and dispersing the same in water, wherein at least one of the contained resins is at least one selected from the bond represented by the formula (1) or (2). A colored fine particle dispersion having a seed as a crosslinked structure.
[0017]
2. 2. The colored fine particle dispersion according to the above 1, wherein the resin having a crosslinked structure has at least one of a hydroxyl group, a carboxyl group, an acid anhydride group, and a primary or secondary amino group.
[0018]
3. 3. The colored fine particle dispersion according to 1 or 2, wherein the crosslinked structure is formed after mixing a resin and a coloring material.
[0019]
4. After dissolving the coloring material and the resin in a solvent, emulsifying and dispersing in a water-based liquid using an emulsifier, and then forming the colored fine particle dispersion according to any one of the above 1 to 3, which is formed by a step of removing the solvent. Production method.
[0020]
5. The colored fine particle dispersion according to any one of the above items 1 to 3, wherein a polymerizable emulsifier is used.
[0021]
6. 6. The colored fine particle dispersion according to any one of the above items 1 to 3, which has a core-shell structure.
[0022]
7. 7. The colored fine particle dispersion according to any one of the above 1 to 3, 5 and 6, wherein the volume average particle diameter of the colored fine particles is 10 to 100 nm.
[0023]
8. 8. The colored fine particle dispersion according to the item 7, wherein the coefficient of variation of the volume-converted average particle diameter is 80% or less.
[0024]
9. A water-based ink comprising the colored fine particle dispersion according to any one of the above 1 to 3 and 5 to 8.
[0025]
10. The water-based ink according to the item 9, which is an ink-jet ink.
[0026]
11. An image forming method, wherein the aqueous ink according to the above item 10 is ejected as droplets from an ink jet head based on a digital signal and adheres to an ink receiver.
[0027]
Hereinafter, the present invention will be described in detail.
As described above, when preparing a colored fine particle dispersion containing a dye and a resin (polymer), the dye and the resin (polymer) are dissolved in an organic solvent, emulsified and dispersed in an aqueous phase, and the organic solvent is further removed. Although a method is known, the molecular weight of the polymer cannot be increased so much in order to reduce the emulsion particle size. On the other hand, since various aqueous organic solvents are used for use in the ink-jet ink, resistance to the aqueous organic solvent, that is, solvent resistance is required. For this purpose, it is better that the polymer has a large molecular weight. Therefore, as a method of increasing the molecular weight of the resin of the colored fine particles, a method of crosslinking at the time of emulsification or after emulsification is considered. Also in Patent Document 1 or 2, crosslinking is performed after emulsification to increase the molecular weight. Attempts to achieve both atomization and solvent resistance simultaneously have been disclosed, and colored polymer fine particles having a crosslinked structure have been disclosed. However, in a dispersion of ultrafine particles (particle diameter of 100 nm or less) such as an ink-jet ink, as the aqueous dispersion becomes finer, these groups that form a urethane cross-linking are formed by a reaction in the particles or the resin. Also, the reaction with water on the particle surface and the crosslinking between the particles become dominant, and the crosslinking reaction in the fine particles tends to be suppressed. As a result, the effect of improving the solvent resistance is not seen, or particles are aggregated, and in severe cases, coarse particles are formed.
[0028]
In addition, in a preferred colored fine particle dispersion, in order to ensure the dispersion stability of the fine particles, the polymer resin used preferably contains a hydrophilic group such as a hydroxyl group, a carboxyl group, and an amino group. It is difficult to use a cross-linking agent such as a polyisocyanate reactive with these, a resin having an isocyanate group, or the like.
[0029]
Therefore, in the present invention, the above-mentioned disadvantage has been solved by using the amide ester represented by the above formula (1) or (2) or a cross-linking agent that forms a hydrazone bond.
[0030]
The cross-linking due to the formation of the amide ester bond can be easily formed, for example, by using a resin having a carboxyl group as a resin to be colored with a coloring material and using a compound having an oxazoline group as a cross-linking agent.
[0031]
That is, in a colored fine particle dispersion obtained by mixing a coloring material and a resin and dispersing in water, using a resin containing a carboxyl group, after forming the dispersion, and mixing and treating with a compound having an oxazoline group at the time of dispersion. By doing so, an amide ester bond is formed by the reaction of the oxazoline group with the carboxyl group (part or all of the carboxyl group in the resin). The cross-links formed are preferably less cross-linking between particles and react with water in an aqueous medium than those due to urethane bonds or the like.
[0032]
As the carboxyl group-containing polymer, for example, an acrylic resin having acrylic acid, methacrylic acid, or the like as a copolymer component is typical, and these carboxyl group-containing polymers are mixed and dissolved with a coloring material to form an aqueous medium. Is dispersed in water. In order to increase the polymerization degree of the polymer by cross-linking, Epocross WS series (for example, Epocross WS-500, Epocross WS-700) and Epocross K series (for example, Epocross K-1010E, Epocross K-2010E, Epocross K-) manufactured by Nippon Shokubai. Oxazoline group-containing polymers such as 1020E, Epocloth K-2020E, Epocloth K-2030E) and Epocloth RPS series (for example, Epocloth RPS-1005) can be mixed with an aqueous phase as a cross-linking agent at the time of dispersion or after dispersion. In such a case, a heat treatment or the like is performed after the dispersion to cause a crosslinking reaction. Epocross WS series and Epocross K series are water-soluble or water-dispersible polymers, respectively, and are used when emulsified or mixed after emulsification in an aqueous medium or water in which the resin is mixed and dispersed with a coloring material. In the case where the skeletal polymer is hydrophobic as described above, it is preferable to mix and dissolve it with a resin together with, for example, a coloring material before use.
[0033]
As a result, an amide ester bond as shown below is formed as a crosslinked structure, the molecular weight is increased, and the solvent resistance is greatly increased.
[0034]
Embedded image

[0035]
Here, R 'also represents a polymer residue, and R "represents a polymer residue of a crosslinking agent linked to a reactive oxazoline group. If an oxazoline group in the polymer residue is present, it reacts with another carboxyl group. The oxazoline group may be substituted as long as the reactivity is not hindered.
[0036]
In addition, the crosslinking by the hydrazone bond represented by the formula (2) is more effective than the crosslinking by the urethane bond between the particles and the reaction with water in the aqueous medium with less reaction in the colored fine particles. It is preferable that it is formed. For the formation of the hydrazone bond, for example, the following hydrazide-based crosslinking agent having active hydrogen
H₂NHNCO-R ″ -CONHNH₂
Are preferred examples of the compound forming a crosslink.
[0037]
Here, R ″ represents a divalent group such as alkylene or arylene, and these groups may have a substituent as long as the properties as a crosslinking agent are not particularly impaired.
[0038]
Examples thereof include adipic acid hydrazide (ADH) and isophthalic acid dihydrazide (IDH) manufactured by Kyowa Hakko Co., Ltd., and for example, these are used. On the other hand, carbonyl which can react with such active hydrogen as a polymer is used. Use of an acrylic copolymer having a monomer component having a functional group such as diacetone acrylamide (manufactured by Kyowa Hakko) as a copolymer component as a resin (polymer) for forming a colored fine particle dispersion Thus, a cross-link by a hydrazone bond can be formed.
[0039]
Embedded image

[0040]
The hydrazone bond is essentially due to the reaction between active hydrogen and a functional group that reacts with the active hydrogen. These active hydrogen or the functional group may be present in either the resin or the crosslinking agent. The cross-linking reaction can efficiently form cross-links in the particles, and can surely increase the molecular weight of the polymer resin used, irrespective of the presence of water or the like around the particles of the aqueous colored fine particle dispersion. In addition, unlike the crosslinking by the reaction of isocyanate and an amine which is an active hydrogen compound, the reaction site is limited to the inside of the particles, or the crosslinking between the particles is small and aggregation does not easily occur.
[0041]
Therefore, forming such a cross-linking is preferable for increasing the molecular weight of the colored polymer resin fine particles having a particle size in the range of 10 nm to 100 nm used in the present invention, such as ink jet, and improving the solvent resistance. It is.
[0042]
In the present invention, various resins (polymers) constituting the colored fine particles can be used, and it is preferable that at least one kind of the polymer has a Tg of 10 ° C. or more.
[0043]
Resins (polymers) that can be used in the present invention include, when a compound having an oxazolyl group is used as a crosslinking agent, and when a hydrazone bond is formed, a hydrolyzate such as a carboxyl group (or an acid anhydride group) is used. And a group having an active carbonyl group may be contained in the resin.
[0044]
In order to increase the compatibility with the coloring material, for example, a polymer having a monomer component having an acid anhydride group such as maleic anhydride is mixed with the coloring material, and after dissolving or dispersing or at the time of dispersing, hydrolysis is performed to form a carboxyl group. It may be preferable to form them.
[0045]
Further, since a resin having self-emulsifying property is preferable in terms of increasing the dispersion stability of the dispersion, an ionic group such as a hydroxyl group or the carboxyl group or a small amount of a sulfonic acid group or a phosphoric acid group, or a quaternary ammonium group And polymers containing a primary or secondary amino group are preferred. However, since monomers constituting each component are available, polymers having these functional groups can be prepared by radical polymerization of each polymerizable vinyl monomer according to a conventional method. It is preferable to polymerize and synthesize.
[0046]
Specific examples of preferred copolymerized vinyl monomers that form the copolymer include, for example, vinyl acetate, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, isononyl acrylate, acrylic Dodecyl acid, octadecyl acrylate, 2-phenoxyethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, methacrylic acid Cyclohexyl, stearyl methacrylate, benzyl methacrylate, [2-acetoacetoxyethyl methacrylate], triethylene glycol methacrylate, ethoxytriethylene glycol methacrylate, methacrylate Le glycidyl, phenyl methacrylate, diacetone acrylamide (DAAM), styrene, alpha-methyl styrene, maleic acid, and vinyl monomers such as acrylonitrile.
[0047]
The copolymer of the vinyl polymerizable monomer used as the resin (polymer) according to the present invention contains a hydroxyl group-containing monomer in an amount of 40% by mass or less, more preferably 25% or less, and a carboxyl group-containing monomer. A monomer having a hydrophilic group such as a sulfonic acid group, a phosphoric acid group, a quaternary ammonium group, or a primary or secondary amino group, for example, a monomer such as 2-acrylamido-2-methylpropanesulfonic acid or diethylaminoethyl methacrylate; It is preferable to use at a ratio of 20% by mass or less, preferably 10% by mass or less, from the viewpoint of forming a stable electric double layer and improving dispersion stability, and from the viewpoint of affinity with a coloring material.
[0048]
In order to react with the crosslinking agent having an oxazolyl group, the carboxyl group must be contained in the range of 0.3 to 20% by mass, preferably in the range of 0.5 to 15% by mass. If the amount is too large, the affinity with the coloring material is impaired, which is not preferable.
[0049]
To form a hydrazone bond, the resin (polymer) reacts with hydrazide, so that an activity of methacrylic acid [2-acetoacetoxyethyl], diacetone acrylamide (DAAM) or the like as a copolymerization component of the vinyl polymerizable monomer. A polymer containing 0.3 to 20% by mass or less, preferably 0.5 to 15% by mass or less of a monomer having a suitable carbonyl group is used. If the amount is too large, the compatibility with the coloring material is affected as described above.
[0050]
By subjecting these polymerizable vinyl monomers to radical copolymerization using a known technique, an uncrosslinked polymer resin according to the present invention can be obtained.
[0051]
Further, in the present invention, it is preferable that the copolymer resin further contains a resin having a structure represented by the following general formula (1). Such a resin may be contained together with the above resin, but a vinyl polymerizable monomer having such a group is marketed, and a vinyl polymerizable monomer having such a group as a component of the copolymer polymer. Is preferably contained. By introducing these structures into the polymer, a cross-linking reaction occurring between particles can be further suppressed.
[0052]
General formula (1)
-(EO)_m-(PO)_n-R
Here, EO represents an ethylene oxide group, and PO represents a propylene oxide group, which are randomly or block copolymerized, respectively. These ethylene oxide groups and propylene oxide groups represented by EO or PO may be further substituted. m and n are each an integer from 0 to 500, 2 ≦ m + n ≦ 500, and R represents a substituent such as a hydrogen atom, a hydroxyl group or an alkyl group, an aryl group or a heterocyclic group. Preferred alkyl groups include straight-chain or branched alkyl groups having 1 to 22 carbon atoms such as methyl, ethyl and butyl, and also alicyclic groups such as cyclopropyl groups and cyclopentyl groups having 1 to 22 carbon atoms. There may be. These may be further substituted with another substituent. The aryl group is a group such as a phenyl group and a naphthyl group, and may be substituted with a substituent having no active hydrogen. Examples of the heterocyclic group include heterocyclic groups such as aziridine, pyrrolidine, furan, thiophene, pyrrole, pyrazole, imidazole, oxazole, thiazole, pyridine, and pyridazine, but are not limited thereto. And may further have a substituent.
[0053]
The group represented by R in the above general formula (1), which is the terminal of the polyethylene oxide group or the polypropylene oxide group, preferably does not contain a crosslinkable functional group such as a carboxyl group or an active carbonyl group. . Inter-particle crosslinking can occur.
[0054]
The proportion of the monomer component having a polyethylene oxide group or a polypropylene oxide group represented by the general formula (1) is 1 to 60% by mass, more preferably 3 to 50% by mass, and preferably 3 to 40% by mass in the polymer component. It is preferable to include them. These groups are considered to protect the surface three-dimensionally, whereby the cross-linking reaction occurring between the particles can be further suppressed, which is preferable. If the amount is too large, the whole polymer becomes hydrophilic, the affinity with the dye is reduced, and phase separation is caused.
[0055]
Specific examples of the polymerizable vinyl monomer having a polyethylene oxide group and a polypropylene oxide group represented by the general formula (1) include a Blenmer series manufactured by NOF Corporation, and typically, a Blenmer PE series (PE-90, PE-200, PE-350), Blemmer AME series (Blemmer AME-400, etc.), Blemmer PME series, (Blemmer PME-1000, Blemmer PME-4000, etc.), Blemmer 50 POEP-800B, Blemmer 55 PET series (Blemmer 55 PET800, etc.) There is.
[0056]
A polymer having a group necessary for cross-linking (preferably further having a polyethylene oxide group and a polypropylene oxide group) is mixed with a coloring material and emulsified in an aqueous medium to prepare an aqueous dispersion of colored fine particles. Sometimes or afterwards, the cross-linking is formed in the particles by treating and reacting with a cross-linking agent for forming the cross-link (for example, the oxazoline compound or the hydrazide compound).
[0057]
In the present invention, some compositions are shown in Synthesis Examples in Examples for examples of preferred polymers as resins.
[0058]
Further, as described above, in the present invention, a coloring material and a resin are mixed, emulsified and dispersed in an aqueous medium, and thereafter, an organic solvent and the like are distilled off to obtain a colored fine particle dispersion. When forming a colored fine particle dispersion, an emulsifier can be used if necessary. Examples of the emulsifier that can be used for emulsification include ordinary nonionic emulsifiers, for example, polyoxyethylene ocalkyl ethers such as polyoxyethylene lauryl ether; for example, polyoxyethylene such as polyoxyethylene nonylphenyl ether. Alkyl phenyl ethers; sorbitan higher fatty acid esters such as sorbitan monolaurate;
Examples of anionic emulsifiers include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfate salts such as sodium lauryl sulfate; and polyoxyethylene lauryl Polyoxyethylene alkyl ether sulfates such as sodium ether sulfate; alkyl sulfosuccinates such as sodium dioctyl sulfosuccinate and derivatives thereof can be used.
[0059]
Further, it is preferable to use a polymerizable emulsifier (reactive emulsifier) instead of or in addition to the emulsifier.
[0060]
The reactive emulsifier is not particularly limited as an anionic emulsifier or a nonionic emulsifier. For example, an emulsifier having a radical polymerizable unsaturated group such as a (meth) allyl group, a (meth) acryl group, and a styryl group may be used alone. Or in combination of two or more.
[0061]
The reactive emulsifier is not particularly limited as an anionic emulsifier or a nonionic emulsifier. For example, an emulsifier having a radical polymerizable unsaturated group such as a (meth) allyl group, a (meth) acryl group, and a styryl group may be used alone. Or in combination of two or more.
[0062]
Examples of such an anionic reactive emulsifier include reactive emulsifiers represented by the following general formulas (3) to (6).
[0063]
Embedded image

[0064]
Where R²Is hydrogen, methyl, R³Is an alkyl, alkenyl, aryl or aralkyl group having 6 to 18 carbon atoms, R⁴Is hydrogen or a methyl group, R⁵Is an alkyl group, alkenyl group, aryl group or aralkyl group having 6 to 18 carbon atoms, X is a single bond or a methylene group, M is an alkali metal, m is a natural number of 1 to 50, n is a natural number of 1 to 50, and q is It is 0 or 1.
[0065]
Specific examples of the anionic reactive emulsifier represented by the general formula (3) include, for example, “Adecaria Soap SE-10N”, “Adecaria Soap SE-20N”, “Adecaria Soap SE-30N” ( As described above, as specific examples of the anionic reactive emulsifier represented by the general formula (4), "Aqualon HS-05", "Aqualon HS-10", and "Aqualon HS-10" Aqualon HS-20 "and" Aqualon HS-30 "(all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). Specific examples of the anionic reactive emulsifier of the above general formula (5) include" Latemul ". S-120 "," Latemul S-120A "," Latemul S-180 "," Latemul S-180A "(all manufactured by Kao Corporation)," Eleminor JS-21 "(all manufactured by Sanyo Chemical) Specific examples of the anionic reactive emulsifier represented by the general formula (6) include “Antox MS-60” (manufactured by Nippon Emulsifier Co., Ltd.).
[0066]
Other anionic reactive emulsifiers include, for example, alkyl alkenyl succinate salt-based reactive emulsifiers such as "Latemul ASK" (manufactured by Kao Corporation); and "Eleminor RS-30" (manufactured by Sanyo Chemical Industries, Ltd.). ) And other polyoxyalkylene (meth) acrylate sulfate ester-based reactive emulsifiers; for example, polyoxyalkylene alkyl ether aliphatic esters such as "RA-1120" and "RA-2614" (all manufactured by Nippon Emulsifier Co., Ltd.). Saturated dicarboxylic ester salt-based reactive emulsifier; for example, (meth) acrylic acid sulfoalkyl ester salt-based reactive emulsifier such as "ANTOX MS-2N" (manufactured by Nippon Emulsifier Co., Ltd.); dihydroxyalkyl (meth) acrylate phthalate Sulfate-based reactive emulsifier; for example, “H-3330PL” (Daiichi Kogyo Seiyaku) Mono- or di (glycerol-1-alkylphenyl-3-allyl-2-polyoxyalkylene ether) phosphate ester-based reactive emulsifiers, etc .; Reactive emulsifiers represented by the following general formulas (7) and (8) can be exemplified.
[0067]
Embedded image

[0068]
Where R²Is hydrogen, methyl, R³Is an alkyl group having 6 to 18 carbon atoms, m is a natural number of 1 to 50, alkenyl group, aryl group or aralkyl group, R⁴Is hydrogen or a methyl group, X is a single bond or a methylene group, and M is an alkali metal.
[0069]
Specific examples of the nonionic reactive emulsifier represented by the general formula (7) include, for example, “Adecaria Soap NE-10”, “Adecaria Soap NE-20”, and “Adecaria Soap NE-30” (the above) Examples of the nonionic reactive emulsifier represented by the general formula (7) include “AQUALON RN-10”, “AQUALON RN-20”, and “AQUALON RN”. -30 "and" AQUALON RN-50 "(both manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and others, for example," RMA-564 "and" RMA-568 "(both manufactured by Nippon Emulsifier Co., Ltd.) Polyoxyalkylene alkyl phenyl ether (meth) acrylate-based reactive emulsifiers such as "RMA-1114" (manufactured by Nippon Emulsifier Co., Ltd.) Ether (meth) acrylate-based reactive emulsifier or the like can also be exemplified.
[0070]
The amount of the reactive emulsifier to be used is generally 0.1 to 30 parts by mass, preferably 2 to 25 parts by mass, particularly preferably 3 to 20 parts by mass, per 100 parts by mass of the total polymer.
[0071]
These emulsifiers form a stable electric double layer in the vicinity of the particles and have reactivity with the resin, so that the polyethylene oxide chain and the polypropylene oxide chain can be introduced into the resin during or after emulsification, Specifically, when cross-linking is introduced later, inter-particle cross-linking on the particle surface can be prevented, which is preferable. In the present invention, a polyethylene oxide chain or a polypropylene oxide chain may be introduced into the resin as described above.
[0072]
Next, the coloring material enclosed in the seed particles together with the polymer will be described.
As the coloring material, any coloring material that can be dissolved or dispersed in the polymer can be used without particular limitation, and examples thereof include an oil dye, a disperse dye, a direct dye, an acid dye, and a basic dye. However, it is preferable to use an oil dye and a disperse dye from the viewpoint of good encapsulation. Particularly preferred specific examples of the disperse dye are shown below, but are not limited thereto. Particularly preferred specific examples include C.I. I. Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 93, 99, 100, 119, 122, 124, 126, 160, 184: 1, 186, 198, 199, 204, 224 and 237; . I. Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1, 177 , 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; I. Disperse Bio Red 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 C., 257, 266, 267, 287, 354, 358, 365 and 368; I. Disperse Green 6: 1 and 9 and the like. On the other hand, the oil-based dye is not limited to the following, but particularly preferred specific examples include, for example, C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 29, 56 and 82; C.I. I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 51, 72, 73, 132 and 218; I. Solvent Violet 3; I. Solvent Blue 2, 11, and 70; I. Solvent Green 3 and 7; and C.I. I. Solvent Orange 2 and the like.
[0073]
It is also possible to use a pigment insoluble in water or various organic solvents dispersed in a polymer medium.
[0074]
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelated azo pigments; and phthalocyanine pigments, perylene and perylene pigments; Dye lakes such as cyclic pigments, basic dye lakes, and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments; and inorganic pigments such as carbon black.
[0075]
Specific organic pigments are exemplified below.
Pigments for magenta or red include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.
[0076]
Examples of orange or yellow pigments include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.
[0077]
Examples of green or cyan pigments include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.
[0078]
The average particle size of the pigment dispersion used in the ink of the invention is preferably from 10 to 200 nm, more preferably from 10 to 150 nm, even more preferably from 10 to 100 nm. If the average particle diameter of the pigment dispersion exceeds 150 nm, the glossiness of an image recorded on a glossy medium is deteriorated, and the transparency of an image recorded on a transparency medium is significantly deteriorated. Further, when the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.
[0079]
The particle size of the pigment dispersion can be measured by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method, or the like. In addition, it is also possible to obtain a particle image by a transmission electron microscope on at least 100 particles or more, and to obtain the image by performing statistical processing using image analysis software such as Image-Pro (manufactured by Media Cybernetics). It is possible.
[0080]
Metal complex dyes such as those disclosed in JP-A-9-277693, JP-A-10-20559, and JP-A-10-30061 can also be used as coloring materials. For example, dyes represented by formulas (I) and (II) described in JP-A-10-20559 can be used.
[0081]
Embedded image

[0082]
In the general formula (I), X¹Represents a group of atoms having a structure capable of forming at least a bidentate coordination bond with a metal ion;¹Is an aromatic hydrocarbon ring, a 5- or 6-membered heterocyclic ring, or -L⁴= Y²And Y²Represents a 5- or 6-membered nitrogen-containing heterocyclic ring. L¹, L⁴Represents a substituted or unsubstituted methine group and a nitrogen atom;², L³Represents a substituted or unsubstituted methine group. M represents a metal ion, X¹And at least a bidentate coordination bond with the group of atoms formed by m represents an integer of 0, 1, 2 or 3, and n1 represents an integer of 1, 2 or 3. In the general formula (II), X³, Y³, M and n2 are each X¹, Y¹, M and n1.
[0083]
Further, specific examples thereof include the following dyes.
[0084]
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[0085]
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[0086]
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[0087]
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[0088]
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[0089]
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[0090]
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[0091]
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[0092]
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[0093]
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[0094]
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[0095]
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[0096]
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[0097]
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[0098]
With respect to the method of producing the coloring material and the colored fine particles composed of the resin, it can be produced by various emulsification methods. Various methods can be used as the emulsification method. Examples of these are summarized, for example, on page 86 of “Progress of Functional Emulsifiers / Emulsification Technology and Application Development”. In the present invention, it is particularly preferable to use an emulsifying and dispersing apparatus using ultrasonic waves, high-speed rotational shearing, and high pressure.
[0099]
In emulsification and dispersion by ultrasonic waves, two types, a so-called batch type and a continuous type, can be used. The batch method is suitable for producing a relatively small amount of sample, and the continuous method is suitable for producing a large amount of sample. In the continuous method, for example, an apparatus such as UH-600SR (manufactured by SMT Co., Ltd.) can be used. In the case of such a continuous system, the irradiation time of the ultrasonic wave can be obtained by (dispersion chamber volume / flow rate × circulation number). In the case where there are a plurality of ultrasonic irradiation devices, it is determined as the sum of the respective irradiation times. The irradiation time of the ultrasonic wave is practically 10,000 seconds or less. In addition, if it is required to be 10,000 seconds or more, the load on the process is large, and in practice, it is necessary to shorten the emulsification dispersion time by reselecting an emulsifier or the like. Therefore, 10,000 seconds or more are not necessary. More preferably, it is 10 seconds or more and 2000 seconds or less.
[0100]
Examples of the emulsifying and dispersing apparatus using high-speed rotational shear include disperser mixers as described on pages 255 to 256 of "Progress of Functional Emulsifiers / Emulsification Technology and Application Development CMC", and pages 251. Such a homomixer, an ultramixer described on page 256, and the like can be used. These types can be properly used depending on the liquid viscosity at the time of emulsification and dispersion. In these high-speed shearing emulsifying and dispersing machines, the rotation speed of the stirring blade is important. In the case of an apparatus having a stator, the clearance between the stirring blade and the stator is usually about 0.5 mm and cannot be extremely narrow, so that the shearing force mainly depends on the peripheral speed of the stirring blade. If the peripheral speed is 5 m / S or more and 150 m / S or less, it can be used for emulsification and dispersion of the present invention. If the peripheral speed is low, it is often impossible to achieve a small particle size even if the emulsification time is extended, and it is necessary to increase the performance of the motor extremely to achieve 150 m / S. More preferably, it is 20 to 100 m / s.
[0101]
In emulsification and dispersion by high pressure, LAB2000 (manufactured by SMT Corporation) and the like can be used, but the emulsification / dispersion ability depends on the pressure applied to the sample. Pressure is 10⁴kPa-5 × 10⁵The range of kPa is preferable. Further, emulsification / dispersion may be performed several times as necessary to obtain a target particle size. If the pressure is too low, the target particle size cannot be achieved in many cases even if emulsification and dispersion are performed many times.⁵In order to make the pressure kPa, a large load is applied to the apparatus, which is not practical. More preferably, 5 × 10⁴kPa ~ 2 × 10⁵The range is kPa.
[0102]
These emulsifying / dispersing devices may be used alone, but may be used in combination as needed. A colloid mill, a flow jet mixer, etc. alone cannot achieve the object of the present invention, but in combination with the apparatus of the present invention, it is possible to enhance the effects of the present invention such as enabling emulsification and dispersion in a short time. is there.
[0103]
In the present invention, the oil-soluble dye, together with the polyethylene oxide group or polypropylene oxide group, and a copolymer resin having a crosslinkable group such as an isocyanate group, after dissolving and mixing in an organic solvent such as ethyl acetate, After emulsifying and dispersing with a dispersing device and removing the solvent to form an aqueous dispersion, a crosslinking agent, for example, an amine compound such as 3-aminopropanol is mixed with the emulsified and dispersed aqueous dispersion to form a crosslink. Let it. To promote the reaction, for example, if necessary, the aqueous dispersion is warmed in the range of 40-90 ° C. and left for a sufficient amount of time (depending on the crosslinks formed, It is also preferable to allow the reaction to take place over several hours) to allow the crosslinking reaction inside the fine particles to be sufficiently performed.
[0104]
When the reaction is relatively slow, these crosslinking agents may be mixed and dissolved together with a polymer and a dye, and then emulsified and dispersed.
[0105]
Here, the aqueous dispersion refers to a dispersion in which the coloring fine particles are dispersed in an aqueous medium mainly composed of water, for example, a water-insoluble or water-soluble organic solvent may be mixed. A water-based medium mainly composed of water means a medium in which the proportion of water in the medium is 50% or more, and the water-based ink has the same meaning.
[0106]
Further, as the organic solvent for dissolving and dispersing the polymer, the coloring material and the like according to the present invention, an organic solvent having a low boiling point (for example, 150 ° C. or lower, preferably 100 ° C. or lower) is preferable. Solvents such as ethyl, butyl acetate, methyl ethyl ketone, butanol, and cyclohexanone can be preferably used.
[0107]
The colored fine particle dispersion according to the present invention is obtained by adding a polymerizable material to the colored fine particle dispersion containing the coloring material and the resin (polymer) formed as described above as seed particles, polymerizing the dispersion, It may have a structure.
[0108]
As a method of adding a polymerizable material and performing seed polymerization on seed particles, after forming a dispersion of colored fine particles containing a coloring material and a resin, a polymerizable unsaturated double bond is formed as a polymerizable material. In the present invention, a method is preferred in which a monomer having the compound is added, emulsion polymerization is performed in the presence of an activator, and the emulsion polymerization is carried out and simultaneously deposited on the surface of the colored fine particles serving as seed particles. When formed in this manner, if preferred, the post-added monomer having a polymerizable unsaturated double bond is polymerized on the seed particles to form a polymer shell.
[0109]
Colored fine particles composed of a colorant and a resin are used as seed particles, and monomers having a polymerizable unsaturated double bond to be subsequently added thereto and polymerized on the seed particles include ethylene, propylene, butadiene, vinyl chloride, and vinylidene chloride. , Vinyl acetate, styrene, (meth) acrylic esters, (meth) acrylic acid, etc., compounds selected from acrylamides, etc., styrene, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic (Meth) acrylic esters such as ethylhexyl acid are preferred, and in addition to these monomers, monomers having a polymerizable unsaturated double bond containing a hydroxyl group in the molecule, for example, hydroxyethyl (meth) acrylate Such as hydroxyalkyl (meth) acrylate or polymerizable polymer having hydroxyl group A monomer having a sum double bond, in the whole raw material monomer to be added post, up to 50 percent, other ethylenically unsaturated double bond it is preferable to polymerize both used as a mixture with a monomer having a.
[0110]
Preferred examples of such a copolymer include styrene / 2-hydroxyethyl methacrylate and styrene / 2-hydroxyethyl acrylate.
[0111]
Further, for reasons such as increasing the stability of the shell, ethylenic acid containing a dissociable group having a pKa value of 3 to 7 such as a monomer containing a carboxylic acid such as acrylic acid or methacrylic acid or a monomer containing a sulfonic acid. Unsaturated monomers may be used up to 10% of the copolymerization component. By using these monomer components for shell formation, the stability of the aqueous dispersion of the core / shell colored fine particles is improved.
[0112]
In the present invention, the amount of the polymer used in the shell is 5% by mass or more and 95% by mass or less of the total amount of the polymer. If the amount is less than 5% by mass, the thickness of the shell is insufficient, and a part of the core containing a large amount of the coloring material tends to appear on the particle surface. On the other hand, if the amount of the polymer in the shell is too large, the ability of the core to protect the coloring material tends to be reduced. More preferably, the content is 10% by mass or more and 90% by mass or less.
[0113]
The total amount of the coloring material is preferably 20% by mass or more and 1000% by mass or less based on the total amount of the polymer. If the amount of the coloring material is too small as compared with the polymer, the image density after ejection will not increase, and if the amount of the coloring material is too large, sufficient protection of the polymer will not be obtained.
[0114]
The colored fine particles of the colored fine particle dispersion according to the present invention thus formed have an average particle size in terms of volume of 10 to 150 nm, preferably 10 to 100 nm, and are stable in this particle size range. And at the same time, have excellent stability when used as an ink.
[0115]
Further, a dispersion having a variation coefficient of the volume average particle diameter of 80% or less is preferable, and the fluctuation of the particle diameter with time is small.
[0116]
The volume average particle diameter was determined by converting the average particle diameter in a circle, which was obtained from the average value of the projected area (determined for at least 100 particles) of a transmission electron microscope (TEM) photograph, into a spherical form. In addition, the volume average particle diameter and its standard deviation were determined, and the standard deviation was divided by the volume average particle diameter to obtain a coefficient of variation. Alternatively, the coefficient of variation can be determined using the dynamic light scattering method. For example, it can be determined using a laser particle size analysis system manufactured by Otsuka Electronics Co., Ltd., or a Zetasizer manufactured by Malvern.
[0117]
The coefficient of variation of the particle size is a value obtained by dividing the standard deviation of the particle size by the particle size. The larger the value, the wider the distribution of the particle size. When the coefficient of variation of the volume average particle size is 80% or more, the particle size distribution becomes very wide, and the surface properties between the particles vary, thereby easily causing aggregation of the particles. In addition, the aggregation of the particles easily causes light scattering of the coloring material on the medium, and also tends to cause deterioration in image quality.
[0118]
The thus-formed colored fine particle dispersion according to the present invention is preferably such that the polymer is incorporated in the polymer emulsion type aqueous ink of the present invention in an amount of 0.5 to 50% by mass as a total polymer amount. More preferably, it is blended in an amount of 0.5 to 30% by mass. When the amount of the polymer is less than 0.5% by mass, the ability to protect the coloring material is not sufficient, and when the amount exceeds 50% by mass, the storage stability of the suspension as ink deteriorates, Since the thickening of the ink and the aggregation of the suspension due to the evaporation of the ink may cause the clogging of the printer head, it is preferable to be within the above range.
[0119]
On the other hand, the coloring material is preferably contained in the ink in an amount of 1 to 30% by mass, more preferably 1.5 to 25% by mass. When the amount of the coloring material is less than 1% by mass, the print density is insufficient, and when the amount is more than 30% by mass, the temporal stability of the emulsion is reduced and the particle size tends to increase due to aggregation or the like. It is preferable to be within the range.
[0120]
The aqueous ink of the present invention is an aqueous medium mainly composed of water, and is composed of an emulsion of a polymer in which the coloring material is encapsulated, and the emulsion includes various conventionally known additives, for example, a wetting agent such as a polyhydric alcohol, It may contain a dispersant, an antifoaming agent such as a silicone type, a fungicide such as a chloromethylphenol type and / or a chelating agent such as EDTA, and an oxygen absorbent such as a sulfite.
[0121]
Since the inside of the colored fine particle dispersion according to the present invention is crosslinked and has high solvent resistance, among these additives, various organic solvents, in particular, the following wetting agents such as polyhydric alcohols ( (It has the effect of realizing a low surface tension) and has high stability in the coexistence, and hardly causes aggregation.
[0122]
Examples of the wetting agent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycol mono n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene. Glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, etc. In addition, Polyhydric alcohols such as sundiol and ethers thereof, acetates, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, triethanolamine, formamide, nitrogen-containing compounds such as dimethylformamide, dimethyl sulfoxide Water-soluble organic solvents such as side and the like can be mentioned. One or more of these can be used as a wetting agent. The amount of these wetting agents is not particularly limited, but preferably 0.1 to 50% by mass, more preferably 0.1 to 30% by mass, in the ink.
[0123]
The dispersing agent is not particularly limited, but its HLB value is from 8 to 18, since the effect as a dispersing agent is exhibited and the suspension has an effect of suppressing increase in particle diameter. preferable.
[0124]
Commercial products can also be used as dispersants. Examples of such commercially available products include, for example, Kao Corporation's dispersant Demol SNB, MS, N, SSL, ST, P (trade name).
[0125]
The amount of the dispersant is not particularly limited, but is preferably 0.01 to 10% by mass in the ink of the present invention. If the compounding amount of the compound is less than 0.01% by mass, it is difficult to reduce the particle size of the suspension, and if it exceeds 10% by mass, the emulsion particle size increases, the emulsion stability decreases, and gelation occurs. There is a possibility that there is a possibility that it is within the above range.
[0126]
The defoaming agent is not particularly limited, and a commercially available product can be used. Examples of such commercially available products include KF96, 66, 69, KS68, 604, 607A, 602, 603, KM73, 73A, 73E, 72, 72A, 72C, 72F, 82F, 70, 71 manufactured by Shin-Etsu Silicone Co., Ltd. 75, 80, 83A, 85, 89, 90, 68-1F, 68-2F (trade name) and the like. The amount of these compounds is not particularly limited, but is preferably 0.001 to 2% by mass in the polymer emulsion type aqueous ink of the present invention. If the compounding amount of the compound is less than 0.001% by mass, bubbles are easily generated at the time of ink preparation, and it is difficult to remove small bubbles in the ink. If it exceeds 2% by mass, the generation of bubbles is suppressed. During printing, repelling may occur in the ink and the printing quality may be degraded.
[0127]
The inkjet head using the aqueous ink for inkjet recording of the present invention may be of an on-demand type or a continuous type. Examples of the discharge method include an electro-mechanical conversion method (for example, a single-cavity type, a double-cavity type, a bender type, a piston type, a shared mode type, a shared wall type, etc.) and an electro-thermal conversion method (for example, thermal ink jet. , Or a bubble jet (R) type).
[0128]
In the image formation using the aqueous ink for inkjet recording of the present invention, for example, a printer or the like loaded with the aqueous ink for inkjet recording discharges the ink as droplets from an inkjet head based on a digital signal and attaches the ink to an ink receptor. Thus, for example, an ink jet print in which an ink jet recorded image is formed on an ink jet image recording medium is obtained.
[0129]
As the inkjet image recording medium, for example, any of plain paper, coated paper, cast-coated paper, glossy paper, glossy film, and OHP film can be used. Among them, for example, a so-called void layer having a porous layer formed thereon It is preferable that the recording medium has the following. The material or shape of the above-described support is not particularly limited. For example, the support may have a three-dimensional structure in addition to a sheet-like material.
[0130]
The water-based ink of the present invention can be used as an ink for writing instruments such as a general fountain pen, a ball-point pen, and a felt-tip pen, in addition to the ink for inkjet recording. The suspension of the present invention can be dried to obtain fine powder. The obtained powder can also be used for an electrophotographic toner.
[0131]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Synthesis Examples and Examples, but the present invention is not limited to the scope of these Examples.
[0132]
<Resin synthesis 1>
A 3 liter four-necked flask was equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux condenser, 20 g of dehydrated methyl ethyl ketone was injected, and the mixture was heated to 80 ° C. The monomers having the composition ratios shown in Table 1 below were weighed so that the total amount was 100 g, and a mixed solution obtained by adding 2 g of N, N'-azobisisovaleronitrile to the monomers was added to the flask over 2 hours. The mixture was dropped and reacted at the same temperature for 5 hours. Thereafter, 80 g of methyl ethyl ketone was added thereto, followed by cooling to obtain a 50% by mass polymer solution. The gelled polymer was insoluble in acetone and ethyl acetate. (R-1 to R-11)
[0133]
[Table 1]

[0134]
Blemmer PME-1000:
-(EO)_m-CH₃  Methacrylate having (m ≒ 23)
Blemmer PP-800:
-(PO)_mMethacrylate having -H (m ≒ 13)
Blemmer AME-400:
-(EO)_m-CH₃  Acrylate having (m ≒ 9)
Here, EO;₂CH₂O- is replaced by PO; -C₃H₆Represents O-, all above are made by NOF Corporation.
HEMA: 2-hydroxyethyl methacrylate, ST: styrene, MMA: methyl methacrylate, SMA: stearyl methacrylate, Karenz MOI: 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko), Blenmer G: glycidyl methacrylate, MAA: methacrylic acid , DAAM: diacetone acrylamide (manufactured by Kyowa Hakko)
<Resin synthesis 2>
A 3 liter four-necked flask was equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux condenser, and 20 g of dehydrated methyl ethyl ketone was poured into the flask and heated to 60 ° C. After adding 9.1 g of 2-hydroxyethylaminopropylamine (manufactured by Koei Chemical), 10.9 g of Blemmer G and reacting for 5 hours, 10 g of DAAM, 40 g of ST, 30 g of Blemmer PME-1000, and furthermore 2 g of N, N'-azobisisovaleronitrile was added dropwise over 2 hours, the temperature was raised to 80 ° C., and the reaction was carried out for 6 hours. Thereafter, 80 g of methyl ethyl ketone was added thereto, followed by cooling to obtain a polymer solution containing a primary and secondary amine having a polymer concentration of 50% by mass. (R-12)
<Manufacture of colored fine particles>
(Production of dye-colored fine particle dispersion having hydrazone bond)
In a pot of CLEARMIX CLM-0.8S (manufactured by M Technique Co., Ltd.), 12 g of C.I. I. Solvent Yellow 162 ((1) dye) and 120 g of ethyl acetate were added, and stirred to completely dissolve the dye. Further, as shown in Table 2, 24 g of a liquid containing 12 g of resin was added ((2) resin), and 270 g of an aqueous solution containing sodium lauryl sulfate (SDS) or KH-05 (Daiichi Kogyo) was added ((3)). Thereafter, the mixture was emulsified at 20,000 rpm for 5 minutes while maintaining the temperature at 40 ° C. After removing the organic solvent under reduced pressure, adipic dihydrazide (A1) or polyisocyanate (N3300, manufactured by Sumika Bayer Urethane) (A2) was added, and a crosslinking reaction was performed at 80 ° C. for 120 minutes. Colored fine particle dispersions 1 to 7 were produced.
[0135]
[Table 2]

[0136]
(Production of dye-colored fine particle dispersion having amide ester bond)
In the production method of the colored fine particle dispersion 1, as (2), Epocross K-2020E (manufactured by Nippon Shokubai Co., Ltd.) having 24 g of a liquid containing 12 g of R-7 and having an oxazoline group which reacts with a carboxylic acid in an aqueous phase during emulsification 6) 40 g of a 40% liquid was added and reacted at 80 ° C. for 5 hours to obtain a colored fine particle dispersion 8 in the same manner except that no other crosslinking agent was added (particle size: 80 nm, the present invention). Further, a colored fine particle dispersion 9 (particle size: 80 nm, comparative example) was obtained without adding a crosslinking agent.
[0137]
Further, the colored fine particle dispersion 8 was kept at 80 ° C., and 3 g of MMA and 3 g of an aqueous solution containing 0.1 g of potassium persulfate were added over 1 hour, and the mixture was allowed to react for 5 hours to obtain colored fine particles having a core-shell structure. Dispersion 10 was obtained.
[0138]
<Solvent resistance evaluation>
To 4 g of each of the colored fine particle dispersions 1 to 10, 1 g of a 10% by mass aqueous solution of 1,2-pentanediol was slowly added, and after stirring well, the mixture was allowed to stand at 60 ° C. for one week, and the rate of change in particle diameter was calculated. . Here, the particle size is a volume average particle size, and as described above, the projected area (at least 100) of a photograph taken using a transmission electron microscope (TEM), specifically, JEM-2000FX manufactured by JEOL Ltd. The average particle diameter in terms of a circle obtained from the average value of (determined for particles or more) was converted to a spherical form. Further, the volume average particle diameter and its standard deviation were obtained, and the standard deviation was divided by the volume average particle diameter to obtain a coefficient of variation.
[0139]
Change in particle size: particle size after one week at 60 ° C / immediate particle size
I asked for it. Table 3 shows the results.
[0140]
[Table 3]

[0141]
It can be seen that the colored fine particles according to the present invention have a small rate of change in particle size and good solvent resistance.
[0142]
【The invention's effect】
A colored fine particle dispersion having good solvent resistance, excellent dispersion stability, and good storage stability was obtained as an inkjet ink.

Claims (11)

A colored fine particle dispersion obtained by mixing a coloring material and a resin and dispersing the same in an aqueous medium, wherein at least one kind of the contained resin is at least one selected from a bond represented by the following formula (1) or (2). A colored fine particle dispersion comprising one kind as a crosslinked structure.

The colored fine particle dispersion according to claim 1, wherein the resin having a crosslinked structure has at least one of a hydroxyl group, a carboxyl group, an acid anhydride group, and a primary or secondary amino group. The colored fine particle dispersion according to claim 1, wherein the crosslinked structure is formed after mixing a resin and a coloring material. The colored fine particle dispersion according to any one of claims 1 to 3, wherein the coloring material and the resin are dissolved in a solvent, and then emulsified and dispersed in an aqueous liquid using an emulsifier, and then formed by a step of removing the solvent. Manufacturing method. The colored fine particle dispersion according to any one of claims 1 to 3, wherein a polymerizable emulsifier is used. The colored fine particle dispersion according to any one of claims 1 to 3, which has a core-shell structure. The colored fine particle dispersion according to any one of claims 1 to 3, and 5, wherein the volume average particle diameter of the colored fine particles is 10 to 100 nm. The dispersion of colored fine particles according to claim 7, wherein the coefficient of variation of the volume-converted average particle diameter is 80% or less. An aqueous ink comprising the colored fine particle dispersion according to any one of claims 1 to 3 and 5 to 8. The aqueous ink according to claim 9, which is an ink jet ink. An image forming method comprising discharging the aqueous ink according to claim 10 from an inkjet head as a droplet based on a digital signal and attaching the droplet to an ink receiver.