JP4931166B2 - Pigment dispersion, ink composition and recording method - Google Patents

Description

【００２１】
一般式（２）：
【化２】

【００２２】
一般式（１）〜（２）のポリマーとしては、例えば、ＨＰ−１２１Ａ、パピオゲン−Ｐ−１０５、ＨＰ−１８２−Ａ（以上、センカ（株）製）が挙げられる。
【００２３】
特に好ましくは、センカＰ-105、センカＨＰ121Ａ，センカＨＰ182Ａ（以上、センカ（株）製）、ポリフィックス700（昭和高分子（株）製）など、4級のものから選択する。
例えば,ＡＭＰとかトリブチルアミンとかのアミンで飛散し難いポリアミンを選択して、部分的に使用することにより中和溶解工程を省略することもできる。
【００２４】
〔カチオンアニオンコンプレックスの形成〕
アニオンカチオンコンプレックスの作製方法は、アニオンポリマーを中和し、ここにカチオンポリマーを添加してアニオンカチオンコンプレックスを凝集物として析出させ、さらに該凝集物を乾燥させた後にアルカリを添加して、中和溶解してアニオン性ポリマーとカチオン性ポリマーとがイオン結合してコンプレックスを形成した状態にする方法であればよいが、好ましくは、以下の方法によれば、良好な物性のコンプレックスを得ることができる。
すなわち、アニオンポリマー溶液カチオンポリマー溶液とを、混合するのであるが、まず、アニオンポリマーのアミン中和水溶液のような中和水溶液と、カチオンポリマーに酢酸のような酸を混合した水溶液とを、各々、均一に撹拌するのに適した濃度に希釈しておき、これらを混合する事で、透明もしくは白色の凝集物としてコンプレックスを発生させる。
【００２５】
アニオンポリマーとカチオンポリマーの希釈は、イオン交換水で行なうのが望ましい。
アニオンポリマーの水への中和溶解には、アンモニアの他にトリエチルアミン、トリエタノールアミン、などの有機アミン、水酸化カリウム、水酸化ナトリウムなどに代表される無機アミンが使用できる。
【００２６】
カチオンポリマーに酸を混合した希釈液を調製するに際して使用する酸は限定されず、例えば、ぎ酸、酢酸、乳酸に代表される有機酸、塩酸、硫酸などに代表される無機酸が挙げられる。
凝集物として発生したコンプレックスを吸引濾過し、ペーストとして回収し、乾燥機を７０℃から１００℃に設定して乾燥させ、コンプレックス凝集物の乾燥固形物を得る。この時に塩酸、酢酸等の酸は、飛散する。なお乾燥時の温度は適宜調整すればよい。
【００２７】
コンプレックス凝集物を分散剤として機能させるべく、これを水溶液化する。中和剤としてＫＯＨなどのアルカリを使用して、中和溶解を行えばよい。
中和溶解は、樹脂の酸価や中和率などに合わせて自由に選択配合出来る。
【００２８】
分散剤としての機能は主に、アニオン側のＫ+で中和コンプレックスとして存在している、カルボキシル基等の官能基によると考えられる。
液中では、4級アミン等のカチオンは、ＣＯＯ―をカウンターイオンとして存在している。これが、液中で分散に寄与しているかどうかは不明であるが、印字後、乾燥を始めるとこのカチオンが、活動をはじめ、紙表面への吸着（ＯＤアップ）、境界のにじみ防止を発動していると推測される。
【００２９】
前記カチオン性ポリマーとアニオン性ポリマーの使用割合（固形分量）は、印字濃度および鮮明度の点、また耐水性の点から、アニオンポリマー100重量部に対してカチオンポリマー13〜50重量部である。カチオンポリマーの量が多すぎても少なすぎても分散性が十分でなくなる。
【００３０】
また、本発明の顔料分散液、インキ組成物に含まれるアニオンカチオンコンプレックスの含有量は、顔料１００重量部に対し１０〜３０重量部以下、特に好ましくは２０〜２５重量部で十分に分散性を発揮する。また、より多量に配合することによりバインダー効果を持たせて耐擦過性を付与することもできる。この場合には、特に好ましくは、顔料１００重量部に対して５０〜６０重量部が適切である。
【００３１】
アミン価で表現されるカチオン官能基量と酸価として表現されるアニオン官能基量のバランスによってカチオンポリマーと混合してコンプレックス化した際の状態が異なり、中和後に、水溶性化するものとエマルジョン化してしまう物とがある。コンプレックスの酸価は限定されないが、良好な状態のコンプレックスとしては、好ましくは１００以上、特に好ましくは１５０以上である。ここでの酸価は以下の方法で測定したものである。
イオン交換水８７重量部、コンプレックス１０重量部、２５％アンモニア水３重量部（計１００重量部）をよく混合して均一な状態にした後、ＫＯＨで滴定していくことにより酸価を求める。
【００３２】
〔色材〕
本発明の色材としては限定されない。特に高いＯＤ値と耐候性を得るには顔料分散系のインキを用いるとよいが、本発明はこのような顔料分散系のインキにも好適に使用できる。
本発明のインク組成物に使用される顔料は特に限定がなく、有機顔料及び無機顔料のいずれも使用することができる。
有機顔料としては、たとえばアゾレーキ、不溶性モノアゾ顔料、不溶性ジスアゾ顔料、縮合アゾ顔料、キレートアゾ顔料などのアゾ顔料；フタロシアニン顔料、ペリレン顔料、ペリノン顔料、アントラキノン顔料、キナクリドン顔料、ジオキサジン顔料、チオインジゴ顔料、イソインドリノン顔料、キノフタロン顔料などの多環式顔料；塩基性染料型キレート、酸性染料型キレートなどの染料キレート；ニトロ顔料；ニトロソ顔料などがあげられる。
【００３３】
無機顔料としては、たとえば酸化チタン、酸化鉄、べんがら、酸化クロム、紺青、群青、モリブデン赤、鉄黒、黄鉛、カーボンブラックなどがあげられ、これらは単独でまたは２種以上を混合して用いることができる。
【００３４】
なかでも、耐光性を考慮すれば、イソインドリノン系顔料、キナクリドン系顔料、縮合アゾ系顔料、フタロシアニン系顔料、キノフタロン系顔料、アントラキノン系顔料、カーボンブラックが好適に用いられる。
【００３５】
前記有機顔料の具体例としては、例えばピグメント・イエロー１（カラー・インデックス（以下、Ｃ．Ｉ．という）１１６８０）、ピグメント・イエロー３（Ｃ．Ｉ．１１７１０）、ピグメント・イエロー１４（Ｃ．Ｉ．２１０９５）、ピグメント・イエロー１７（Ｃ．Ｉ．２１１０５）、ピグメント・イエロー４２（Ｃ．Ｉ．７７４９２）、ピグメント・イエロー７４（Ｃ．Ｉ．１１７４１）、ピグメント・イエロー８３（Ｃ．Ｉ．２１１０８）、ピグメント・イエロー９３（Ｃ．Ｉ．２０７１０）、ピグメント・イエロー９８（Ｃ．Ｉ．１１７２７）、ピグメント・イエロー１０９（Ｃ．Ｉ．５６２８４）、ピグメント・イエロー１１０（Ｃ．Ｉ．５６２８０）、ピグメント・イエロー１２８（Ｃ．Ｉ．２００３７）、ピグメント・イエロー１３８（Ｃ．Ｉ．５６３００）、ピグメント・イエロー１３９（Ｃ．Ｉ．５６２９８）、ピグメント・イエロー１４７（Ｃ．Ｉ．６０６４５）、ピグメント・イエロー１５４（Ｃ．Ｉ．１１７８１）、ピグメント・イエロー１５５、ピグメント・イエロー１８０（Ｃ．Ｉ．２１２９０）、ピグメント・イエロー１８５、ピグメント・オレンジ５（Ｃ．Ｉ．１２０７５）、ピグメント・オレンジ１３（Ｃ．Ｉ．２１１１０）、ピグメント・オレンジ１６（Ｃ．Ｉ．２１１６０）、ピグメント・オレンジ３４（Ｃ．Ｉ．２１１６０）、ピグメント・オレンジ４３（Ｃ．Ｉ．７１１０５）、ピグメント・オレンジ６１（Ｃ．Ｉ．１１２６５）、ピグメント・オレンジ７１（Ｃ．Ｉ．５６１２００）、ピグメント・レッド５（Ｃ．Ｉ．１２４９０）、ピグメント・レッド８（Ｃ．Ｉ．１２３３５）、ピグメント・レッド１７（Ｃ．Ｉ．１２３９０）、ピグメント・レッド２２（Ｃ．Ｉ．１２３１５）、ピグメント・レッド４８：２（Ｃ．Ｉ．１５８６５：２）、ピグメント・レッド１１２（Ｃ．Ｉ．１２３７０）、ピグメント・レッド１２２（Ｃ．Ｉ．７３９１５）、ピグメント・レッド１７７（Ｃ．Ｉ．６５３００）、ピグメント・レッド２０２（Ｃ．Ｉ．７３９０７）、ピグメント・レッド２５４（Ｃ．Ｉ．５６１１０）、ピグメント・バイオレット１９（Ｃ．Ｉ．４６５００）、ピグメント・バイオレット２３（Ｃ．Ｉ．５１３１９）、ピグメント・ブルー１５：１（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー１５：３（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー１５：４（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー６０（Ｃ．Ｉ．６９８００）、ピグメント・グリーン７（Ｃ．Ｉ．７４２６０）、ピグメント・グリーン３６（Ｃ．Ｉ．７４２６５）などが挙げられる。
【００３６】
無機顔料の具体例としては、たとえばピグメント・イエロー４２（Ｃ．Ｉ．７７４９２）、ピグメント・ホワイト６（Ｃ．Ｉ．７７８９１）、ピグメント・ブルー２７（Ｃ．Ｉ．７７５１０）、ピグメント・ブルー２９（Ｃ．Ｉ．７７００７）、ピグメント・ブラック７（Ｃ．Ｉ．７７２６６）などがあげられる。
【００３７】
好ましくは、ピグメント・イエロー７４（Ｃ．Ｉ．１１７４１）、ピグメント・イエロー１０９（Ｃ．Ｉ．５６２８４）、ピグメント・イエロー１１０（Ｃ．Ｉ．５６２８０）、ピグメント・イエロー１２８（Ｃ．Ｉ．２００３７）、ピグメント・イエロー１５５、ピグメント・イエロー１８０（Ｃ．Ｉ．２１２９０）、ピグメント・レッド１２２（Ｃ．Ｉ．７３９１５）、ピグメント・レッド２０２（Ｃ．Ｉ．７３９０７）、ピグメント・バイオレット１９（Ｃ．Ｉ．４６５００）、ピグメント・ブルー１５：１（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー１５：３（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー１５：４（Ｃ．Ｉ．７４１６０）、ピグメント・ブルー６０（Ｃ．Ｉ．６９８００）、ピグメント・ブラック７（Ｃ．Ｉ．７７２６６）などが挙げられる。
【００３８】
高いＯＤ値を得るには顔料として特にカーボンブラックを用いるのが好ましく、カーボンブラックとして中でも、以下のものが好適である。
一次粒子径は５０ｎｍ以下、特に好ましくは４０ｎｍ以下、さらに好ましくは３０ｎｍ以下である。ストラクチャーとしては２４Ｍ４ＤＢＰ吸収量が７０ｇ／１００ｍｌ以上、さらに好ましくは８０ｇ／１００ｍｌ以上である。このようなカーボンブラックは、紙の繊維の間に浸透していかないネットワークを形成しやすく高いＯＤ値を出しやすいと考えられる。なおここで一次粒子径は電子顕微鏡による値であり、ＤＢＰ吸収量はJIS K 6221 Ａ法による値である。２４Ｍ４ＤＢＰ吸収量は以下の方法で測定する。試料を所定量金属シリンダー中に仕込み、24,000psi(165Mpa)の圧力で、４回の繰り返し圧縮を加えたのち、ＤＢＰ値を求める（ＡＳＴＭ D 3493）。
【００３９】
（溶媒の説明）
分散液の溶媒は、コンプレックスを可溶化し、後述するインキ組成物のインキ特性を損なわないものであれば特に限定されず用いられる。コンプレックスの種類によって選択すればよいが、代表的には、メタノール、エタノール、ｎ−プロパノール、２−エチルヘキサノール、シクロヘキサノール、ジエチレングリコール、アセトン、ＭＥＫ、メチルイソブチルケトン、ジ−イソブチルケトン、エチルアセテート、ｎ−ブチルアセテート、エチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテルが挙げられる。
【００４０】
本発明の顔料分散液の製造方法は特に限定されないが、以下の方法によれば効率的に得ることができる。すなわち、顔料とアニオンカチオンコンプレックスを混合攪拌したのち、分散機にて処理し、顔料を微粒子状に分散させる。顔料とアニオンカチオンコンプレックスの混合物は水性媒体中で処理される。また、処理に用いる分散機としては、例えばメディア媒体型分散機や衝突型分散機が挙げられる。
【００４１】
分散機は、メディアを使用する物、メディアレスの物など分散可能な物であれば,何でも良い。
メディアミルで使用する場合は,各種の種類のメディアを使用できる。
メディア媒体型分散機とは、ベッセル内で、媒体としてガラス、アルミナ、ジルコニア、スチール、タングステンなどの小径のメディアを高速で運動させ、そのあいだを通過するスラリーをメディア間の剪断力で摩砕させるものをいう。かかるメディア媒体型分散機の具体例としては、たとえば、ボールミル、サンドミル、パールミル、アジテータミル、コボールミル、ウルトラビスコミル、スパイクミル、ウルトラファインミルなどが挙げられる。
【００４２】
衝突型分散機とは、１つの壁面に流体を高速で衝突させるか、流体同士を高速で衝突させて流体中の顔料などを粉砕させるものをいう。かかる衝突型分散機の具体例としては、たとえばナノマイザー、ホモゲナイザー、マイクロフルイダイザー、アルチマイザーなどが挙げられる。
これら以外にもロールミル、超音波分散機などの他の公知の分散機を用いても構わない。
【００４３】
顔料分散液中の顔料の粒子径は５ｎｍ以上２５０ｎｍ以下であるのが好ましい。粒子径が２５０ｎｍをこえると顔料の分離や沈降が発生しやすくなる。また５ｎｍより小さいと粒子の制御や耐光性などの性能が劣ってくる。特に好ましくは１００〜２００ｎｍの範囲とする。
なお、ここでの粒子径は、顔料が実際に分散液中で形成している粒子としての分散径であり、測定装置として、マイクロトラックＵＰＡ（ＬＥＥＤＳ＆ＮＯＲＴＨＲＵＰ社）を使用したものである。
【００４４】
本発明の顔料分散液は、以上説明した顔料、アニオンカチオンコンプレックス及び媒体として水その他の水性媒体を含有するものであるが、その他、各種の有機溶剤を含有させてもよい。ここで、水性媒体とは、水又は水と相溶し得る水溶性の溶媒をいう。水としてはイオン交換水を用いるのが特に好ましい。水溶性の溶媒としては、後述する、インク組成物において用いられる溶媒から選択するのが望ましい。
【００４５】
顔料分散液におけるその他の成分として、分散液の物性に悪影響を与えたりインキ化した際に障害となるものでなければ限定されず、適宜選択することができるが、以下に説明する水性インク組成物において用いられる有機溶剤から選択した溶剤や、水性インク組成物への添加剤である防カビ剤等を含有していてもよい。
【００４６】
〔インク組成物〕
本発明のインク組成物は、前述したアニオンカチオンコンプレックスを少なくとも含有することを特徴とする。色材としては前述した顔料が好ましく用いられる。
本発明のインク組成物の製造方法は特に限定されないが、顔料分散液を調製し、粗大粒子が含まれている場合は遠心処理を施して除去するのが望ましく、その後、有機溶剤等を添加してインク化工程に進むのが好ましい。
【００４７】
インク組成物中の色材の含有量は、特に顔料を用いた場合、着色効果が充分に発現されるようにするには、０．５重量％以上、好ましくは２重量％以上であることが望ましく、またインク組成物の粘度において、吐出性能を良好に保持しうる適性粘度にするには、２５重量％以下、好ましくは１０重量％以下であることが望ましい。
【００４８】
本発明のインク組成物に用いる有機溶剤は、インクジェット用インクに使用した場合、ヘッド部分の目詰まり防止や印字した時のかすれを改善する働きを有する。
【００４９】
好ましい有機溶剤の具体例としては、たとえば、水溶性有機溶剤として、エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、プロピレングリコール、ブチレングリコール、１，２，６−ヘキサントリオ−ル、チオグリコール、ヘキシレングリコール、グリセリン、ジグリセリン、２−ピロリドン、Ｎ−メチル−２−ピロリドン、１，５−ペンタンジオ−ル、１，３−ジメチル−２−イミダゾリジノンの中から選ばれ、これらは単独でまたは２種以上を混合して用いることができる。
【００５０】
有機溶剤の添加量は、インク液中に５重量％から３０重量％、好ましくは６重量％から２５重量％が望ましく、それ以上の添加では、インク自体が高粘度となり、インクの安定性や吐出性が悪くなったり、紙へのにじみが大きく、しかも乾燥速度が遅くなったりする。とりわけ粘度は２０mPa・s以下が好ましい。
【００５１】
上記以外の有機溶剤を添加してもよく、たとえば、メタノール、エタノール、ｎ−プロパノール、ｉｓｏ−プロパノール、ｎ−ブタノール、ｉｓｏ−ブタノール、ｔ−ブタノール、トリメチロールプロパン、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などがあげられる。
さらに皮膜性アップのために、バインダー樹脂を添加してもよい。公知の皮膜性の樹脂、例えばウレタン樹脂、アクリル樹脂、ポリエステル樹脂、ＰＶＡ、ＰＶＰ、アミド樹脂、エポキシ樹脂、メチルセルロース等の、水溶性あるいはエマルジョンのものが挙げられる。
【００５２】
さらに、本発明のインク組成物には、所望の物性を有するようにするために、防カビ剤、消泡剤、防錆剤、防腐剤などの添加剤を適宜配合することができる。
以上説明した本発明の水性インク組成物は特にインクジェット用インクとして優れていることは上述した通りである。具体的な使用方法としては、例えば、上述の水性インク組成物をインクジェットプリンターのノズルより吐出させて印字を行うことを特徴とするインクジェット記録方法、あるいは上述の水性インク組成物に熱エネルギーを作用させて液滴を形成し、この液滴を以て記録を行うことを特徴とするインクジェット記録方法が挙げられる。
【００５３】
（印字方法の説明）
以上説明した本発明のインキ組成物を、ＰＰＣ用紙、コピー用紙で代表される汎用ＯＡ共用紙に印字することにより、これら汎用ＯＡ共用紙においても、ＯＤ値で代表される着色濃度の高い印字が可能となる。もちろん、本発明のインキ組成物を用いてマットタイプ専用紙等のＩＪ専用紙、IJ対応普通紙に印字することにより、さらにＯＤ値アップを達成することもできる。
また、ＰＰＣ用紙、コピー用紙で代表されるＯＡ用紙、あるいはマットタイプ等のＩＪ専用紙において、複数のインキから印字する記録方法において、これら複数のインキのうち少なくとも１つとして本発明のインキ組成物を用いることにより、このインキ組成物による印字部と、他のインキ組成物による印字部との印字部との境界、特に染料インキと顔料インキの印字境界でのにじみの発生を防止できる。
【００５４】
【実施例】
以下、本発明を実施例によりさらに具体的に説明する。なお以下の実施例において「部」及び「％」は特にことわりのない限り、「重量部」及び「重量％」を表す。
【００５５】
（実施例１〜１２）
〔コンプレックスの形成〕
表−１に示す配合A、配合Bにより各々、アニオンポリマー中和希釈液とカチオンポリマー中和希釈液を調製し、それらを表−１中の混合の欄の割合で均一に混合して凝集体としてコンプレックスを析出させた。析出物を吸引濾過し、ペーストとして回収し、乾燥機を７０℃から１００℃に設定して乾燥させ、コンプレックスの乾燥固形物を得た。
なお表中の数字は配合した「部」を示し、ポリマーの配合量は、固形分としての添加量ではなく見かけの添加量である。表中のポリマー成分の固形分含有量は、表−２に示す。
【００５６】
【表１】
表−１

【００５７】
【表２】
表−２

商品名 有効成分（固形分含有量）
「パピオゲンＰ105」 約70％
「ＨＰ121Ａ」 約70％
「ＨＰ182Ａ」 約50％
【００５８】
〔コンプレックスの中和可溶化〕
得られたコンプレックスを、表−３の処方でKOHとイオン交換水を加えて中和し、水溶液化した。これを２０％コンプレックスＫＯＨ中和液とする。
【００５９】
【表３】
表−３
コンプレックス ２０部
９５．５％ＫＯＨ ４．１９部
イオン交換水 ７５．８１部
計 １００部
【００６０】
〔分散液の作製〕
表−４の処方にしたがい、以下の方法で顔料を分散して分散液を作製した。分散の方法：
表−４の分散配合で配合し、井上製作所製試験用サンドグラインダーにて、メディアとして無アリカリのガラスビーズを使用して２時間分散し、分散液を得た。分散液の初期分散性を表−４に示す。流動性有りのものを○、増粘・ゲル化したものを×とした。
【００６１】
【表４】
表−４

なお、市販のカーボンブラックａ、ｂ、ｃの基本物性は以下の通りである。
カーボンブラックａ：
一次粒子径：１３ｎｍ ＤＢＰ吸収量：１１４ｇ／１００ｍｌ ２４Ｍ４ＤＢＰ吸収量：９０ｇ／１００ｍｌ
カーボンブラックｂ：
一次粒子径：１６ｎｍ ＤＢＰ吸収量：１０８ｇ／１００ｍｌ ２４Ｍ４ＤＢＰ吸収量：８８ｇ／１００ｍｌ
カーボンブラックｃ：
一次粒子径：１９ｎｍ ＤＢＰ吸収量：１６５ｇ／１００ｍｌ ２４Ｍ４ＤＢＰ吸収量：１２５ｇ／１００ｍｌ
【００６２】
〔インキの調製〕
前記の分散液を、以下の処方でインキ化した。
インキ化処方
２―ピロリドン 5部
１．５−ペンタンジオール 8部
グリセリン 5部
サーフィノール465 1部
分散液
顔料分としてインキの4％となるよう調整
イオン交換水 Ｘ（全体が100部となるよう調整）
計 100部
【００６３】
〔試験印字物の作成〕
プリンターとしては,キヤノン社製「ＢＪＳ−５００」、「ＭＪ８０００Ｃ」を用いて印字した。
試験用紙としては、ゼロックス４０２４ペーパーを使用した。プリンタードライバーはプリンターに付属のものを用いた。
プリンターの設定を標準モードに設定し、カートリッヂに詰め替えたインキを別添の印字パターンで印字した。
評価結果を、表−５に示す。ＯＤ値はマクベス濃度計で測定した。境界ブリードは、「にじみなし」を○、「にじみ少し」を△、「にじみ有り」を×とした。
【００６４】
【表５】
表−５

【００６５】
（比較例１〜７）
コンプレックスに替えてジョンクリルＪ−６７９を用い、表―３の処方でＫＯＨとイオン交換水を加えて中和、水溶液化した。これを２０％Ｊ−６７９中和液とする。これを表―４の処方に従い、前記の「分散液の作製」に従って分散液を得、前記「インキの調製」にしたがってインキ化し、前記「試験印字物の作成」にしたがって印字し、結果を表―５に示した。
【発明の効果】
本発明によりメディア側に使用して効果のあるカチオンポリマーとして販売されているものを分散剤として使用されるスチレンアクリル樹脂等のアニオン性ポリマーとコンプレックス化し、さらに水溶化することにより、これら双方の有する機能を発揮させることに成功した。
このコンプレックスを用いてカーボンブラックをはじめとする黒色顔料を分散することができ、アニオンポリマーとしての分散性と同時にカチオンポリマーの有する顔料の紙への定着性を印字後に発現することにより、顕著なOD値アップ、境界にじみ（顔料インキ印字部分と染料インキ印字部分との境界でのにじみ、ブリーディング）の防止等の効果を発揮できる分散液及びインキ組成物を得ることができ、これにより、普通紙でも高いＯＤ値と境界にじみの防止を達成できた。また、ＩＪ専用紙を用いれば従来よりさらに高ＯＤ値を達成することもできる。[0001]
BACKGROUND OF THE INVENTION
  The present inventionPigment dispersion,The present invention relates to an ink composition and a recording method.
[0002]
[Prior art]
  In recent years, inkjet printers, which are widely used as low-cost full-color printing methods, eject ink from fine nozzles with a pore size of 200 μm or less, and are mainly dissolved as colorants to prevent clogging at the nozzles. Water-soluble dyes excellent in safety, especially anionic direct dyes and acid dyes are used.
[0003]
  When recording the ink using the water-soluble dye on a medium such as paper, (1) the density of images and characters is high and the color tone is vividly reproduced, and (2) the ink is quickly absorbed by the medium. In addition, there are demands for performance such as ink dots not flowing out, (3) less spreading of ink dots in the lateral direction and no bleeding, and (4) improvement in water resistance of images and characters.
  In order to satisfy these required performances, various types of inkjet recording media have been studied and proposed.
[0004]
  Means for forming a layer for receiving ink-jet ink on a recording material include (1) using an organic polymer-containing coating solution, and (2) inorganic particles such as silica in a solution containing water, a binder, and the like. There are those using a coating solution prepared by dispersing the slag.
  As the method (1), for example, a coating solution containing an anionic polymer and a cationic polymer is used (Japanese Patent Laid-Open Nos. 62-183,794, 62-244,690, JP 3). , 015, 739), and those using a coating solution containing a polymer complex (JP 9-99,634, JP 62-122,781).
[0005]
  In the method (2), the coating liquid is composed of inorganic particles (silica, alumina, etc.), a cation agent as an ink fixing agent, a binder, and the like (Japanese Patent Laid-Open No. 61-35,275, etc.). .
  Moreover, there exists a thing by the combination of a polymer complex and an inorganic particle which the present inventors propose (patent application 2001-170,250).
Of the above, the combination of anion and cation, or those using these complexes, is presumed to have a function due to the bond between the cation resin and paper and the bond to the ink color material of the anion resin.The
[0006]
[Problems to be solved by the invention]
  As described above, various recording materials suitable for ink jet paper have been developed and sold as ink jet exclusive paper. However, there are still many cases where printing is performed using plain paper, and high performance is achieved by printing on plain paper. There is also a great demand for inks that can achieve this.
  Ink-jet inks have been developed in various ways, but especially in the case of pigment-based inks that contain pigments as colorants, it is required that the print density represented by the OD value on the printed media be high. Is done.
  In particular, in the OA scene, similar demands are made on OA common paper represented by PPC paper and copy paper that are not dedicated paper developed for inkjet.
  Similarly, in the case of printing with dye ink on OA paper, bleeding at the boundary between the dye and the pigment becomes a problem.
  In addition, there are ink dropping due to friction called “rubbing resistance”, stain due to overwriting with a fluorescent marker called “marker resistance”, etc., and these are confirmation physical properties in relation to trade-off.
[0007]
  However, in the conventional ink and printing method, the density on the OA co-paper is still insufficient, and there are many problems with boundary blurring, and there are many perfect trade-offs of each physical property. Absent.
  The present invention is not a so-called special paper developed for ink-jet printing, but is sold as OA co-paper. PPC paper, copy paper, etc. have high concentrations represented by OD values, such as dye ink and pigment. The purpose is to enable printing without blurring at the border.
  Therefore, what should be done in order to print pigment ink on plain paper media, which is generally referred to as PPC paper, in a state where the pigment is high in OD and does not blur at the boundary, is a problem.
[0008]
  First, plain paper (PPC paper) is an abbreviation of Plain Paper Copier. The main raw material is pulp (NBKP, LBKP, recently recycled paper), and talc and calcium carbonate are added as an internal additive. In the case of sulfuric acid band (inorganic cation) for "adhesion between pulps and fixing of size", sizing agent (anion) for "paper strength, suction adjustment", in the case of neutral papermaking, This is a paper with exposed pulp, which is composed of a fixing agent (organic cation) that performs “adhesion and size fixing”, a self-fixing type sizing agent, and the like.
[0009]
  The cationic agent used at this time uses the minimum amount for the above-mentioned role.
  On the other hand, as described above, the coated paper such as the IJ exclusive paper covers the surface of the coated paper.
  When printing anionic dye ink, which is often used as inkjet ink on plain paper as described above, or pigment-type ink in which pigment is dispersed, between the pulp fiber and the ink in the bare state Ionic adsorption does not occur and bleeds (specifically) along the pulp fibers and does not settle on the surface of the paper. Since there is no ionic adsorption with the pulp fibers, water resistance problems also occur, particularly in the case of dyes.
[0010]
  In order to remedy such problems, there are papers that are IJ-compatible plain papers, and these include papers that fix inks in particular, and that are adjusted based on the addition of a cationic polymer, size type, and amount added. . Increasing the band is effective, but the preservability of the paper is lowered, so the addition of a cationic polymer is also common. In this way, efforts have been made to improve the fixing to some extent on the pulp surface and to ensure the water resistance of the dye by OD value and bordering, but not so much effect.
  On the other hand, a polymeric dispersant is generally used to finely disperse the pigment. In general, an amine-neutralized anionic water-soluble polymer used as a pigment dispersant generally functions as a dispersant by water-solubilizing a non-cationized anionic functional group with a neutralizer.
[0011]
  If there is such a polymer having a pigment dispersion function and also having a cationic functional group, such a polymer is allowed to exist in the ink so that it can be used only for printing on plain paper. It can be expected to exert the same effect as printed on paper. However, it is necessary to have excellent pigment dispersibility at the same time as such a cationic function, and it is also necessary to satisfy the discharge properties from the nozzles and the printability as ink physical properties, which are now known as commercial products. None of the cationic polymers satisfy these physical properties.
[0012]
  The present inventors have intensively studied to solve such problems. The idea of whether the above problems can be solved by adding these anion resin and cation resin to the ink side, based on the hint of the effect of the complex of anion resin and cation resin proposed as a recording material, as described above. It came to.
[0013]
  First, an attempt was made to add a pigment to an anionic resin and disperse it, and then add a cationic resin to form a complex to make the pigment as fine as possible. It turned out to be difficult.
  The inventor came up with the idea that the complexed material was not dissolved again with a solvent, but a neutralizer was brought in again, neutralized and dissolved in water, and used as a dispersant.
  Since it is useless to make the whole complex, acetic acid was scattered and partially cationized during drying using acetic acid and a cationic polymer as a method of partially forming the complex. Finally, an ink composition according to the present invention, which has excellent printability on plain paper and can express a particularly high OD value, was obtained and reached the present invention. That is, the present invention
(1)An anionic polymer is neutralized, and a cationic polymer is added thereto to precipitate the anionic cation complex as an aggregate. Further, the aggregate is dried, and then an alkali is added to neutralize and dissolve the anionic cation complex. A pigment dispersion, wherein the weight ratio of the anionic polymer to the cationic polymer is 13 to 50 parts by weight of the cationic polymer with respect to 100 parts by weight of the anionic polymer, and the cationic polymer is polyamine, polyamine sulfone, polyvinylamine, polyvinylpyridine , Polyethylenimine, polyethylenimine-epichlorohydrin reactant, polyamidoamine, polyacrylamide, polydiallyldimethylammonium chloride, polyamidoamine-epichlorohydrin resin, melamine-formaldehyde Resins, urea - formaldehyde resins, dicyandiamide - formaldehyde resin, a pigment dispersion liquid is one or more of the mixed resin of a polyamine and a polyamide,
(2)An anionic polymer is neutralized, and a cationic polymer is added thereto to precipitate the anionic cation complex as an aggregate. Further, the aggregate is dried, and then an alkali is added to neutralize and dissolve the anionic cation complex. A pigment ink composition, wherein the weight ratio of anionic polymer to cationic polymer is 13 to 50 parts by weight of cationic polymer with respect to 100 parts by weight of anionic polymer, and the cationic polymer is polyamine, polyamine sulfone, polyvinylamine, polyvinyl Pyridine, polyethyleneimine, polyethyleneimine-epichlorohydrin reactant, polyamidoamine, polyacrylamide, polydiallyldimethylammonium chloride, polyamidoamine-epichlorohydrin resin, melamine-former Dehydrogenase resins, urea - formaldehyde resins, dicyandiamide - formaldehyde resin, a pigment ink composition is one or more of the mixed resin of a polyamine and a polyamide,
(3)Above (2)A recording method comprising printing the ink composition described above on a general-purpose OA paper;
(4)Above (2)The recording method, wherein the ink composition described above is printed on IJ-compatible plain paper or mat-type exclusive paper,
(5) A recording method for printing from a plurality of inks, wherein at least one of the plurality of inks isAbove (2)A recording method comprising the ink composition according to claim 1,
Exist.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail.
[Anion-cation complex]
  The ink composition of the present invention contains an anionic cation complex. Here, the anionic cation complex is characterized in that the anionic resin and the cationic resin are not polymerized but these resins are ionically bonded due to ionicity.
[0015]
  The complex itself can be formed by mixing a solution of an anion resin and a solution of a cation resin in a solvent in which the complex is not dissolved to form a complex as a precipitate (Japanese Patent Application No. 2001-170). , 250), in the present invention, this complex exists in a state of being at least partially dissolved, and functions as a dispersant for a color material such as a pigment by an ionic functional group such as a carboxyl group of an anion resin. Can be considered. At the same time, after printing, it is considered that the effect of preventing OD increase and bleeding can be obtained by adsorption of the cationic resin onto the paper.
[0016]
[Anionic polymer]
  In the present invention, an anionic polymer refers to a polymer having an anionic functional group such as a carboxyl group, a sulfone group, a sulfate ester group, or a phosphate ester group as a functional group. Those in which these anionic functional groups are neutralized with counter ions to be water-solubilized are also included.
  The anionic polymer used in the present invention is not limited as long as it is the above, but typically, for example, styrene-acrylic acid copolymer, polyacrylic acid, styrene-maleic anhydride copolymer, acrylic acid. Examples thereof include ester-acrylic acid copolymers and salts thereof. These anionic polymers are used alone or in admixture of two or more.
[0017]
  Among the anionic polymers, the styrene-acrylic acid copolymer is suitable for application of the treatment liquid to an object to be coated, in particular, impregnation properties and sharpness and recording density when recording on the object with ink. Therefore, it can be used particularly preferably in the present invention. Examples of the styrene-acrylic acid copolymer include John Crill 61J, John Crill 62, John Crill 679, John Crill 67, John Crill 678, John Crill 683, John Crill 690, HPD- 671 (above, manufactured by Johnson Polymer Co., Ltd.).
[0018]
[Cationic polymer]
  In the present invention, the cationic polymer refers to a polymer having a cationic functional group such as an amino group, an imino group, a tertiary amine, a quaternary ammonium base, or hydrazine. Those in which these anionic functional groups are neutralized with counter ions to be water-solubilized are also included.
  Cationic polymer used in the present inventionTheReamine, polyamine sulfone, polyvinylamine, polyvinylpyridine, polyethyleneimine, polyethyleneimine-epichlorohydrin reactant, polyamidoamine, polyacrylamide, polydiallyldimethylammonium chloride, polyamidoamine-epichlorohydrin resin, melamine-formaldehyde resin, urea-formaldehyde Resin, dicyandiamide-formaldehyde resin, mixed resin of polyamine and polyamideOne or more of. These cationic polymers are used alone or in admixture of two or more.
[0019]
  Among the cationic polymers, polyamines are preferable, and among these polyamines, polyamines represented by the following general formulas (1) to (2) can be suitably used in the present invention.
[0020]
  General formula (1):
[Chemical 1]

[0021]
  General formula (2):
[Chemical 2]

[0022]
  Examples of the polymers represented by the general formulas (1) to (2) include HP-121A, papyogen-P-105, and HP-182-A (manufactured by Senka Co., Ltd.).
[0023]
  Particularly preferably, it is selected from four grades such as SENKA P-105, SENKA HP121A, SENKA HP182A (above, manufactured by SENKA Co., Ltd.), POLYFIX 700 (manufactured by Showa Polymer Co., Ltd.).
  For example, the neutralization dissolution step can be omitted by selecting a polyamine that is difficult to be scattered with an amine such as AMP or tributylamine and partially using it.
[0024]
[Formation of cationic anion complex]
The method for producing an anion cation complex is as follows:Neutralize the anionic polymer, add the cationic polymer here to precipitate the anionic cation complex as aggregates, dry the aggregates, add alkali, neutralize and dissolve.Any method may be used as long as the anionic polymer and the cationic polymer are ion-bonded to form a complex. Preferably, according to the following method, a complex having good physical properties can be obtained.
That is, an anionic polymer solution is mixed with a cationic polymer solution.LiquidA neutralized aqueous solution such as this and an aqueous solution obtained by mixing an acid such as acetic acid with a cationic polymer are diluted to a concentration suitable for uniform stirring, respectively, and mixed to obtain a transparent or white solution. Complexes are generated as aggregates.
[0025]
  It is desirable to dilute the anionic polymer and the cationic polymer with ion-exchanged water.
In addition to ammonia, organic amines such as triethylamine and triethanolamine, inorganic amines such as potassium hydroxide and sodium hydroxide can be used to neutralize and dissolve anionic polymers in water.The
[0026]
The acid used for preparing the diluted solution in which the acid is mixed with the cationic polymer is not limited, and examples thereof include organic acids typified by formic acid, acetic acid, lactic acid, inorganic acids typified by hydrochloric acid, sulfuric acid and the like.
The complex generated as aggregates is filtered by suction, collected as a paste, and dried by setting the dryer at 70 ° C. to 100 ° C. to obtain a dry solid of complex aggregates. At this time, acids such as hydrochloric acid and acetic acid are scattered. The drying temperature may be adjusted as appropriate.
[0027]
In order to make the complex aggregate function as a dispersant, it is made into an aqueous solution. Neutralization and dissolution may be performed using an alkali such as KOH as a neutralizing agent.
  Neutralization and dissolution can be freely selected and blended according to the acid value and neutralization rate of the resin.
[0028]
It is considered that the function as a dispersant is mainly due to a functional group such as a carboxyl group that exists as a neutralization complex at K + on the anion side.
  In the liquid, cations such as quaternary amines are present with COO- as a counter ion. It is unclear whether this contributes to dispersion in the liquid, but when printing starts drying after printing, this cation activates activity, adsorbs on the paper surface (OD up), and prevents bleeding at the boundary. I guess that.
[0029]
  The use ratio (solid content) of the cationic polymer and the anionic polymer depends on the print density and the sharpness.point,Is it also water resistant?Et al.The cationic polymer is 13 to 50 parts by weight with respect to 100 parts by weight of the anionic polymer. If the amount of the cationic polymer is too large or too small, the dispersibility is not sufficient.
[0030]
  Further, the content of the anionic cation complex contained in the pigment dispersion and the ink composition of the present invention is 10 to 30 parts by weight or less, particularly preferably 20 to 25 parts by weight, with respect to 100 parts by weight of the pigment. Demonstrate. Further, by adding a larger amount, it is possible to impart a binder effect and impart scratch resistance. In this case, particularly preferably, 50 to 60 parts by weight is appropriate for 100 parts by weight of the pigment.
[0031]
The state when mixed with a cationic polymer to form a complex differs depending on the balance between the amount of cationic functional group expressed by amine value and the amount of anionic functional group expressed by acid value. There are things that turn into.The acid value of the complex is not limited, but the complex in a good state is preferably 100 or more, particularly preferably 150 or more. The acid value here is measured by the following method.
After 87 parts by weight of ion-exchanged water, 10 parts by weight of complex, and 3 parts by weight of 25% aqueous ammonia (total 100 parts by weight) are mixed well to obtain a uniform state, the acid value is determined by titrating with KOH.
[0032]
[Color material]
The color material of the present invention is not limited. In particular, in order to obtain a high OD value and weather resistance, a pigment-dispersed ink may be used. However, the present invention can also be suitably used for such a pigment-dispersed ink.
  The pigment used in the ink composition of the present invention is not particularly limited, and both organic pigments and inorganic pigments can be used.
  Examples of organic pigments include azo pigments such as azo lakes, insoluble monoazo pigments, insoluble disazo pigments, condensed azo pigments, and chelate azo pigments; phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, Polycyclic pigments such as linone pigments and quinophthalone pigments; dye chelates such as basic dye chelates and acid dye chelates; nitro pigments; nitroso pigments and the like.
[0033]
  Examples of the inorganic pigment include titanium oxide, iron oxide, red pepper, chromium oxide, bitumen, ultramarine blue, molybdenum red, iron black, yellow lead, and carbon black. These may be used alone or in combination of two or more. be able to.
[0034]
  Among these, considering light resistance, isoindolinone pigments, quinacridone pigments, condensed azo pigments, phthalocyanine pigments, quinophthalone pigments, anthraquinone pigments, and carbon black are preferably used.
[0035]
  Specific examples of the organic pigment include, for example, Pigment Yellow 1 (Color Index (hereinafter referred to as C.I.) 11680), Pigment Yellow 3 (C.I. 11710), and Pigment Yellow 14 (C.I. Pigment Yellow 17 (C.I. 21105), Pigment Yellow 42 (C.I. 77492), Pigment Yellow 74 (C.I. 11741), Pigment Yellow 83 (C.I. 21108) ), Pigment Yellow 93 (C.I. 20710), Pigment Yellow 98 (C.I. 11727), Pigment Yellow 109 (C.I. 56284), Pigment Yellow 110 (C.I. 56280), Pigment Yellow 128 (C.I.20037), Pigment Ye -138 (C.I. 56300), Pigment Yellow 139 (C.I. 56298), Pigment Yellow 147 (C.I. 60645), Pigment Yellow 154 (C.I. 11781), Pigment Yellow 155 Pigment Yellow 180 (C.I. 21290), Pigment Yellow 185, Pigment Orange 5 (C.I. 12075), Pigment Orange 13 (C.I. 21110), Pigment Orange 16 (C.I. Pigment Orange 34 (C.I. 21160), Pigment Orange 43 (C.I. 71105), Pigment Orange 61 (C.I. 11265), Pigment Orange 71 (C.I. 561200) ), Pigment Red 5 (C.I. 12490) Pigment Red 8 (C.I. 12335), Pigment Red 17 (C.I. 12390), Pigment Red 22 (C.I. 12315), Pigment Red 48: 2 (C.I. 15865: 2), Pigment Red 112 (C.I. 12370), Pigment Red 122 (C.I. 73915), Pigment Red 177 (C.I. 65300), Pigment Red 202 (C.I. 73907) Pigment Red 254 (C.I. 56110), Pigment Violet 19 (C.I. 46500), Pigment Violet 23 (C.I. 51319), Pigment Blue 15: 1 (C.I. 74160) Pigment Blue 15: 3 (C.I. 74160), Pigment Blue 15: 4 (C . I. 74160), Pigment Blue 60 (C.I. 69800), Pigment Green 7 (C.I. 74260), Pigment Green 36 (C.I. 74265), and the like.
[0036]
  Specific examples of the inorganic pigment include, for example, Pigment Yellow 42 (C.I. 77492), Pigment White 6 (C.I. 777891), Pigment Blue 27 (C.I. 77510), and Pigment Blue 29 ( CI.77007) and CI Pigment Black 7 (C.I.77266).
[0037]
  Preferably, Pigment Yellow 74 (C.I. 11741), Pigment Yellow 109 (C.I. 56284), Pigment Yellow 110 (C.I. 56280), Pigment Yellow 128 (C.I. 20037) Pigment Yellow 155, Pigment Yellow 180 (C.I. 21290), Pigment Red 122 (C.I. 73915), Pigment Red 202 (C.I. 73907), Pigment Violet 19 (C.I. Pigment Blue 15: 1 (C.I. 74160), Pigment Blue 15: 3 (C.I. 74160), Pigment Blue 15: 4 (C.I. 74160), Pigment Blue 60 (C.I.69800), Pigment Black 7 (C.I.7 266), and the like.
[0038]
In order to obtain a high OD value, it is particularly preferable to use carbon black as a pigment, and among them, the following are preferable.
The primary particle diameter is 50 nm or less, particularly preferably 40 nm or less, and further preferably 30 nm or less. The structure has a 24M4DBP absorption of 70 g / 100 ml or more, more preferably 80 g / 100 ml or more. Such carbon black is considered to easily form a network that does not penetrate between the fibers of the paper and easily give a high OD value. Here, the primary particle diameter is a value obtained by an electron microscope, and the DBP absorption is a value obtained by a JIS K 6221 A method. The 24M4DBP absorption is measured by the following method. A sample is charged into a metal cylinder in a predetermined amount, subjected to repeated compression four times at a pressure of 24,000 psi (165 MPa), and then a DBP value is obtained (ASTM D 3493).
[0039]
(Description of solvent)
  The solvent of the dispersion is not particularly limited as long as it solubilizes the complex and does not impair the ink characteristics of the ink composition described below. complexofThe type may be selected, but typically, methanol, ethanol, n-propanol, 2-ethylhexanol, cyclohexanol, diethylene glycol, acetone, MEK, methyl isobutyl ketone, di-isobutyl ketone, ethyl acetate, n-butyl Examples include acetate, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether.
[0040]
  The method for producing the pigment dispersion of the present invention is not particularly limited, but can be efficiently obtained by the following method. That is, with pigmentAnion cation complexAre mixed and stirred, and then processed by a disperser to disperse the pigment into fine particles. With pigmentsAnion cation complexIs processed in an aqueous medium. Examples of the disperser used for the processing include a media medium type disperser and a collision type disperser.
[0041]
  Any disperser may be used as long as it can disperse, such as those using media or media-less.
  When used in a media mill, various types of media can be used.
  A media-media type disperser moves small-sized media such as glass, alumina, zirconia, steel, and tungsten as media in a vessel at high speed, and grinds the slurry passing between them with shear force between the media. Say things. Specific examples of such a media medium type dispersing machine include, for example, a ball mill, a sand mill, a pearl mill, an agitator mill, a coball mill, an ultra visco mill, a spike mill, and an ultra fine mill.
[0042]
  The collision-type disperser refers to a type in which a fluid collides with one wall surface at a high speed or a fluid collides with each other at a high speed to pulverize pigments in the fluid. Specific examples of such collision type dispersers include a nanomizer, a homogenizer, a microfluidizer, and an optimizer.
In addition to these, other known dispersers such as a roll mill and an ultrasonic disperser may be used.
[0043]
  Pigment dispersionThe particle diameter of the pigment in it is preferably 5 nm or more and 250 nm or less. When the particle diameter exceeds 250 nm, pigment separation and sedimentation tend to occur. On the other hand, if it is smaller than 5 nm, the performance such as particle control and light resistance is inferior. Especially preferably, it is set as the range of 100-200 nm.
  Here, the particle diameter is a dispersion diameter as a particle that the pigment is actually formed in the dispersion, and a microtrac UPA (LEEDS & NORTHUP) is used as a measuring device.
[0044]
  Of the present inventionPigment dispersionIs the pigment described above,Anion cation complexIn addition, water or other aqueous medium is contained as a medium, but various other organic solvents may be contained. Here, the aqueous medium refers to water or a water-soluble solvent that is compatible with water. It is particularly preferable to use ion exchange water as water. The water-soluble solvent is desirably selected from the solvents used in the ink composition described later.
[0045]
  Pigment dispersionThe other components in are not limited as long as they do not adversely affect the physical properties of the dispersion or become an obstacle when converted to ink, and can be appropriately selected, but are used in the aqueous ink composition described below. You may contain the solvent selected from the organic solvent, the antifungal agent which is an additive to an aqueous ink composition, etc.
[0046]
[Ink composition]
  The ink composition of the present invention is described above.Anionic cationIt contains at least a complex. The pigment described above is preferably used as the color material.
  The method for producing the ink composition of the present invention is not particularly limited. However, it is preferable to prepare a pigment dispersion and remove coarse particles by centrifugation, and then add an organic solvent or the like. Thus, it is preferable to proceed to the ink process.
[0047]
  The content of the coloring material in the ink composition is 0.5% by weight or more, preferably 2% by weight or more, in particular, when a pigment is used, so that the coloring effect is sufficiently expressed. Desirably, the viscosity of the ink composition is 25% by weight or less, preferably 10% by weight or less in order to obtain an appropriate viscosity capable of maintaining good ejection performance.
[0048]
  The organic solvent used in the ink composition of the present invention has a function of preventing clogging of the head part and improving fading when printed when used in an ink jet ink.
[0049]
  Specific examples of preferable organic solvents include, for example, water-soluble organic solvents such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, Selected from xylene glycol, glycerin, diglycerin, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,5-pentanediol, 1,3-dimethyl-2-imidazolidinone, which may be used alone or Two or more kinds can be mixed and used.
[0050]
  The addition amount of the organic solvent is 5% to 30% by weight, preferably 6% to 25% by weight in the ink liquid. If the addition is more than that, the ink itself has a high viscosity, and the stability and ejection of the ink can be improved. It becomes worse and the bleeding on the paper is large and the drying speed is slow. In particular, the viscosity is preferably 20 mPa · s or less.
[0051]
  Organic solvents other than the above may be added, for example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, t-butanol, trimethylolpropane, ethylene glycol monoethyl ether, ethylene glycol And monobutyl ether.
  Further, a binder resin may be added to improve the film property. Examples of known film-forming resins such as urethane resins, acrylic resins, polyester resins, PVA, PVP, amide resins, epoxy resins, and methyl cellulose are water-soluble or emulsion types.
[0052]
  Furthermore, additives such as an antifungal agent, an antifoaming agent, an antirust agent, and an antiseptic can be appropriately added to the ink composition of the present invention in order to have desired physical properties.
  As described above, the water-based ink composition of the present invention described above is particularly excellent as an inkjet ink. As a specific usage method, for example, the above-described aqueous ink composition is ejected from a nozzle of an inkjet printer to perform printing, or thermal energy is allowed to act on the above-described aqueous ink composition. And an ink jet recording method characterized in that recording is performed with the liquid droplets.
[0053]
(Description of printing method)
  By printing the ink composition of the present invention described above on a general-purpose OA common paper typified by PPC paper and copy paper, even on these general-purpose OA common paper, printing with a high color density represented by an OD value can be achieved. It becomes possible. Of course, the OD value can be further increased by printing on IJ paper such as mat-type paper and IJ-compatible plain paper using the ink composition of the present invention.
  Further, in a recording method for printing from a plurality of inks on PPC paper, OA paper typified by copy paper, or IJ dedicated paper such as a mat type, the ink composition of the present invention is used as at least one of the plurality of inks. By using this, it is possible to prevent the occurrence of bleeding at the boundary between the printed portion of this ink composition and the printed portion of the other ink composition, particularly at the boundary between the dye ink and the pigment ink.
[0054]
【Example】
  Hereinafter, the present invention will be described more specifically with reference to examples. In the following examples, “parts” and “%” represent “parts by weight” and “% by weight” unless otherwise specified.
[0055]
(Examples 1-12)
[Complex formation]
  An anionic polymer neutralization dilution liquid and a cationic polymer neutralization dilution liquid are respectively prepared according to the formulation A and the formulation B shown in Table 1, and they are uniformly mixed in the ratio of the mixing column in Table 1 to form an aggregate. The complex was deposited as The precipitate was filtered by suction, collected as a paste, and dried by setting the dryer at 70 ° C. to 100 ° C. to obtain a dry solid of the complex.
  In addition, the number in a table | surface shows the mix | blended "part", and the compounding quantity of a polymer is not the addition amount as solid content but an apparent addition amount. The solid content of the polymer component in the table is shown in Table-2.
[0056]
[Table 1]
Table-1

[0057]
[Table 2]
Table-2

Product name Active ingredient (solid content)
"Papiogen P105" approx. 70%
"HP121A" 70%
“HP182A” approx. 50%
[0058]
[Complex neutralization and solubilization]
  The obtained complex was neutralized by adding KOH and ion-exchanged water according to the formulation shown in Table 3 to form an aqueous solution. This is a 20% complex KOH neutralized solution.
[0059]
[Table 3]
Table-3
ConTheRex 20 copies
9.5.5% KOH 4.19 parts
Ion exchange water 75.81 parts
100 copies in total
[0060]
(Preparation of dispersion)
  According to the formulation shown in Table-4, a pigment was dispersed by the following method to prepare a dispersion. Distribution method:
  It mix | blended by the dispersion | distribution mixing | blending of Table-4, and it disperse | distributed for 2 hours using the non-arikari glass bead as a medium with the sand grinder for testing made from Inoue Seisakusho, and obtained the dispersion liquid. Table 4 shows the initial dispersibility of the dispersion. A sample with fluidity was marked with ◯, and a thickened / gelled product was marked with ×.
[0061]
[Table 4]
Table-4

  The basic physical properties of commercially available carbon blacks a, b, and c are as follows.
Carbon black a:
Primary particle size: 13 nm DBP absorption: 114 g / 100 ml 24M4 DBP absorption: 90 g / 100 ml
Carbon black b:
Primary particle size: 16 nm DBP absorption: 108 g / 100 ml 24M4 DBP absorption: 88 g / 100 ml
Carbon black c:
Primary particle size: 19 nm DBP absorption: 165 g / 100 ml 24M4 DBP absorption: 125 g / 100 ml
[0062]
[Preparation of ink]
  The dispersion was inked according to the following formulation.
Ink formulation
2-pyrrolidone 5 parts
1.5-pentanediol 8 parts
Glycerin 5 parts
Surfinol 465 1 part
Dispersion
Adjust the pigment content to be 4% of the ink
Ion-exchanged water X (adjusted so that the total is 100 parts)
100 copies in total
[0063]
[Creation of test prints]
  Printing was performed using “BJS-500” and “MJ8000C” manufactured by Canon Inc.
  Xerox 4024 paper was used as the test paper. The printer driver that came with the printer was used.
  The printer was set to the standard mode, and the ink refilled in the cartridge was printed with the attached print pattern.
  The evaluation results are shown in Table-5. The OD value was measured with a Macbeth densitometer. For the boundary bleed, “no bleed” is indicated by “◯”, “little bleed” is indicated by △, and “smudge” is indicated by “x”.
[0064]
[Table 5]
Table-5

[0065]
(Comparative Examples 1-7)
  Joncrill J-679 was used instead of the complex, and KOH and ion-exchanged water were added and neutralized to obtain an aqueous solution according to the formulation shown in Table-3. This is designated as 20% J-679 neutralizing solution. In accordance with the prescription in Table-4, a dispersion is obtained according to “Preparation of dispersion” described above, converted into ink according to “Preparation of ink”, printed according to “Preparation of test print”, and the result is shown in Table 4. -Shown in 5.
【The invention's effect】
  According to the present invention, what is marketed as an effective cationic polymer for use on the media side is complexed with an anionic polymer such as styrene acrylic resin used as a dispersant, and further water-solubilized to have both of them. We succeeded in demonstrating the function.
  This complex can be used to disperse black pigments such as carbon black. By exhibiting the dispersibility as an anionic polymer and the fixing property of the pigment possessed by the cationic polymer on paper after printing, a remarkable OD Dispersions and ink compositions can be obtained that can prevent effects such as value increase and boundary bleeding (bleeding and bleeding at the boundary between pigment ink printing part and dye ink printing part). A high OD value and prevention of blurring at the boundary were achieved. Further, if the IJ dedicated paper is used, a higher OD value can be achieved than before.

Claims (5)

An anionic polymer is neutralized, and a cationic polymer is added thereto to precipitate the anionic cation complex as an aggregate. Further, the aggregate is dried, and then an alkali is added to neutralize and dissolve the anionic cation complex. A pigment dispersion, wherein the weight ratio of the anionic polymer to the cationic polymer is 13 to 50 parts by weight of the cationic polymer with respect to 100 parts by weight of the anionic polymer, and the cationic polymer is polyamine, polyamine sulfone, polyvinylamine, polyvinylpyridine , Polyethylenimine, polyethylenimine-epichlorohydrin reactant, polyamidoamine, polyacrylamide, polydiallyldimethylammonium chloride, polyamidoamine-epichlorohydrin resin, melamine-formaldehyde Resins, urea - formaldehyde resins, dicyandiamide - formaldehyde resin, a pigment dispersion liquid is one or more of the mixed resin of polyamines and polyamides. An anionic polymer is neutralized, and a cationic polymer is added thereto to precipitate the anionic cation complex as an aggregate. Further, the aggregate is dried, and then an alkali is added to neutralize and dissolve the anionic cation complex. A pigment ink composition, wherein the weight ratio of anionic polymer to cationic polymer is 13 to 50 parts by weight of cationic polymer with respect to 100 parts by weight of anionic polymer, and the cationic polymer is polyamine, polyamine sulfone, polyvinylamine, polyvinyl Pyridine, polyethyleneimine, polyethyleneimine-epichlorohydrin reactant, polyamidoamine, polyacrylamide, polydiallyldimethylammonium chloride, polyamidoamine-epichlorohydrin resin, melamine-former Dehydrogenase resins, urea - formaldehyde resins, dicyandiamide - formaldehyde resin, a pigment ink composition is one or more of the mixed resin of polyamines and polyamides.   A recording method comprising printing the ink composition according to claim 2 on a general-purpose OA co-paper.   A recording method comprising printing the ink composition according to claim 2 on IJ-compatible plain paper or mat-type exclusive paper.   A recording method for printing from a plurality of inks, wherein at least one of the plurality of inks is the ink composition according to claim 2.