JP2004175984A - Ink set of black ink composition, and recording method, recorded material and ink-jet recording apparatus using the ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set of a black ink composition enabling proper correction of coloring property developing in a medium tone gray and dark gray color, and provide a recording method, a recorded material and an ink-jet recording apparatus using the ink set. <P>SOLUTION: The ink set contains at least one set of a combination of the 1st black ink composition containing carbon black and a coloring agent for complementary color with the 2nd black ink composition containing carbon black at a concentration essentially equal to the carbon black concentration of the 1st black ink composition and free from the coloring agent for complementary color. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、ｐは０〜３の整数である）で表される顔料を添加することにより、中間階調灰色から濃灰色における帯色性が適切に修正され、理想的な無彩色に近いグレースケールを作成可能であることが分かった。
【００２９】
前記式（１）で表される顔料の内、ｐ＝０の場合の化合物は、カラーインデックス・ピグメントブルー６０（Ｃ．Ｉ．ＰＢ６０）として知られている。こうした薄いブラックインク組成物の場合、補色用着色剤不含ブラックインク組成物（及び補色用着色剤含有ブラックインク組成物）におけるカーボンブラック含有量は、それぞれのブラックインク組成物の全重量に対して、０．０１〜１０重量％、好ましくは０．０１〜５重量％、より好ましくは０．１〜３重量％であり、補色用着色剤含有ブラックインク組成物における一般式（１）で表される顔料の含有量は、補色用着色剤含有ブラックインク組成物の全重量に対して、０．０１〜５重量％、好ましくは０．０１〜３重量％、より好ましくは０．１〜３重量％である。
【００３０】
また、本発明のインクセットが、カーボンブラック濃度が比較的に高く、図１において曲線ｄのようなグレースケール軌跡を描く濃いブラックインク組成物を含む場合には、中間階調灰色記録用の補色剤含有ブラックインク組成物に、一般式（２）：
【化６】

で表される顔料を添加すると、中間階調での帯色性が適切に修正され、理想的な無彩色に近いグレースケールを作成することができることが分かった。
【００３１】
前記式（２）で表される顔料は、フタロシアニンブルー顔料であり、カラーインデックス・ピグメントブルー１５：３又はカラーインデックス・ピグメントブルー１５：４などとして知られている。こうした濃いブラックインク組成物の場合、補色用着色剤不含ブラックインク組成物（及び補色用着色剤含有ブラックインク組成物）におけるカーボンブラック含有量は、それぞれのブラックインク組成物の全重量に対して、０．０１〜１０重量％、好ましくは０．０１〜５重量％、より好ましくは０．１〜３重量％であり、一般式（２）で表される顔料の含有量は、補色用着色剤含有ブラックインク組成物の全重量に対して、０．０１〜５重量％、好ましくは０．０１〜３重量％、より好ましくは０．１〜３重量％である。
【００３２】
本発明のインクセットに含まれる各補色用着色剤含有ブラックインク組成物に含有されるカーボンブラックと補色用着色剤との量比は特には限定されず、使用する個々のカーボンブラックの帯色性を修正することのできる量で前記補色用着色剤を含有させればよい。具体的に含有量を決定するには、例えば、使用するカーボンブラックと前記補色用着色剤とを特定比率で含有するインク組成物によって形成される記録像について、前記のようなグレースケール軌跡を作成し、帯色性の修正程度を評価し、その帯色性を適切に修正することのできる両者の含有比率を調整する。
【００３３】
本発明のインクセットを用いて、グレースケールなどを作成する場合に、補色用着色剤含有ブラックインク組成物を用いて記録を行う階調と、補色用着色剤不含ブラックインク組成物を用いて記録を行う階調の選択は、例えば、図４又は図５に示すようなグレースケール軌跡から適宜決定することができる。図４は、図１の曲線ｄのみを残し、もう一方の曲線ｅや破線Ｒ、Ｇ、Ｃ、及びＭなどを削除した模式的グラフであり、図５は、同様に、図１の曲線ｅのみを残した模式的グラフである。
【００３４】
図４の曲線ｄのグレースケール軌跡を示すブラックインク組成物の場合には、図４のａ＊，ｂ＊座標において、例えば、原点（ａ＊＝０及びｂ＊＝０）と、その原点から最も離れた曲線ｄ上の点Ｒ１との距離Ｑを計算し、原点（ａ＊＝０及びｂ＊＝０）からの距離が０．５Ｑ以下の領域については補色用着色剤不含ブラックインク組成物Ｄ１を用い、０．５Ｑより離れた領域については補色用着色剤含有ブラックインク組成物Ｄ２を用いることができる。あるいは、０．５Ｑにて分割する代わりに、例えば、０．３Ｑ〜０．７Ｑ（又は０．４Ｑ〜０．６Ｑ）の間のいずれかの値で二分割することもできる。あるいは、三分割以上に分け、補色用着色剤含有量の異なる２種以上の補色用着色剤含有ブラックインク組成物を用いることもできる。
【００３５】
また、例えば、図５の曲線ｅのグレースケール軌跡を示すブラックインク組成物の場合には、図５のａ＊，ｂ＊座標において、原点（ａ＊＝０及びｂ＊＝０）と、その原点から最も離れた曲線ｅ上の点Ｒ２との距離Ｑを計算し、原点（ａ＊＝０及びｂ＊＝０）からの距離が０．５Ｑ以下の領域については補色用着色剤不含ブラックインク組成物Ｅ１を用い、０．５Ｑより離れた領域については補色用着色剤含有ブラックインク組成物Ｅ２を用いることができる。あるいは、０．５Ｑにて分割する代わりに、例えば、０．３Ｑ〜０．７Ｑ（又は０．４Ｑ〜０．６Ｑ）の間のいずれかの値で二分割することもできる。あるいは、前記と同様に三分割以上に分けることもできる
【００３６】
本発明のインクセットのブラックインク組成物（すなわち、補色用着色剤含有ブラックインク組成物及び補色用着色剤不含ブラックインク組成物）に用いるカーボンブラックとして、例えば、コンタクト法、ファーネスト法、又はサーマル法などの公知の方法によって製造されたカーボンブラックを使用することができる。カーボンブラックとしては、具体的には、三菱化学製のＮｏ．２３００，Ｎｏ．９００，ＭＣＦ８８，Ｎｏ．３３，Ｎｏ．４０，Ｎｏ．４５，Ｎｏ．５２，ＭＡ７，ＭＡ８，ＭＡ１００，Ｎｏ２２００Ｂ等；コロンビア社製のＲａｖｅｎ５７５０，Ｒａｖｅｎ５２５０，Ｒａｖｅｎ５０００，Ｒａｖｅｎ３５００，Ｒａｖｅｎ１２５５，Ｒａｖｅｎ７００等；キャボット社製のＲｅｇａｌ ４００Ｒ，Ｒｅｇａｌ ３３０Ｒ，Ｒｅｇａｌ ６６０Ｒ，Ｍｏｇｕｌ Ｌ，Ｍｏｎａｒｃｈ ７００，Ｍｏｎａｒｃｈ ８００，Ｍｏｎａｒｃｈ ８８０，Ｍｏｎａｒｃｈ ９００，Ｍｏｎａｒｃｈ １０００，Ｍｏｎａｒｃｈ １１００，Ｍｏｎａｒｃｈ １３００，Ｍｏｎａｒｃｈ １４００等；デグッサ社製のＣｏｌｏｒ Ｂｌａｃｋ ＦＷ１，Ｃｏｌｏｒ Ｂｌａｃｋ ＦＷ２，Ｃｏｌｏｒ Ｂｌａｃｋ ＦＷ２Ｖ，Ｃｏｌｏｒ Ｂｌａｃｋ ＦＷ１８，Ｃｏｌｏｒ Ｂｌａｃｋ ＦＷ２００，Ｃｏｌｏｒ Ｂｌａｃｋ Ｓ１５０，Ｃｏｌｏｒ ＢｌａｃｋＳ１６０，Ｃｏｌｏｒ Ｂｌａｃｋ Ｓ１７０，Ｐｒｉｎｔｅｘ ３５，Ｐｒｉｎｔｅｘ Ｕ，Ｐｒｉｎｔｅｘ Ｖ，Ｐｒｉｎｔｅｘ １４０Ｕ，Ｓｐｅｃｉａｌ Ｂｌａｃｋ ６，Ｓｐｅｃｉａｌ Ｂｌａｃｋ ５，Ｓｐｅｃｉａｌ Ｂｌａｃｋ ４Ａ，Ｓｐｅｃｉａｌ Ｂｌａｃｋ ４等を使用することができる。カーボンブラックの粒径は、特に限定されるものではないが、１０μｍ以下が好ましく、更に好ましくは０．１μｍ以下である。
同じインクセットにおいて、同一組に属する各ブラックインク組成物が含有するカーボンブラックは、それぞれ同濃度であり、別の組に属する各ブラックインク組成物が含有するカーボンブラック濃度は相互に異なる。
【００３７】
本発明のインクセットに含まれ補色用着色剤不含ブラックインク組成物は、従来公知のブラックインク組成物と同様の配合成分を含むことができ、補色用着色剤含有ブラックインク組成物は、前記の補色用着色剤を含有することを除けば、それ以外の点では、従来公知のブラックインク組成物と同様の配合成分を含むことができ、それぞれ有機系インク又は好ましくは水系インクとして調製することができる。また、本発明のインクセットは、従来公知の各種の記録方法用インクとして利用することができ、好ましくはインクジェット記録用インクセットとして利用することができる。
以下に、本発明のインクセットがインクジェット記録用であり、各インク組成物が水系インク組成物である場合について簡単に説明する。
【００３８】
インクジェット記録用水系ブラックインク組成物において、カーボンブラック及び前記補色用着色剤は、例えば、分散剤で水性媒体中に分散させた顔料分散液としてインク組成物に添加するのが好ましい。
【００３９】
本発明のインクセットで用いるインクジェット記録用水系ブラックインク組成物は、更に界面活性剤を含有することができる。界面活性剤の具体例としては、アニオン性界面活性剤（例えば、ドデシルベンゼンスルホン酸ナトリウム、ラウリル酸ナトリウム、又はポリオキシエチレンアルキルエーテルサルフェートのアンモニウム塩など）、ノニオン性界面活性剤（例えば、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルエステル、ポリオキシエチレンソルビタン脂肪酸エステル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンアルキルアミン、又はポリオキシエチレンアルキルアミドなど）、両性界面活性剤（例えば、Ｎ，Ｎ−ジメチル−Ｎ−アルキル−Ｎ−カルボキシメチルアンモニウムベタイン、Ｎ，Ｎ−ジアルキルアミノアルキレンカルボン酸塩、Ｎ，Ｎ，Ｎ−トリアルキル−Ｎ−スルホアルキレンアンモニウムベタイン、Ｎ，Ｎ−ジアルキル−Ｎ，Ｎ−ビスポリオキシエチレンアンモニウム硫酸エステルベタイン、又は２−アルキル−１−カルボキシメチル−１−ヒドロキシエチルイミダゾリニウムベタイン）等を挙げることができ、これらは単独で又は二種以上を組合せて使用することができる。
【００４０】
本発明によるブラックインク組成物は、アセチレングリコール系界面活性剤を含むのが好ましい。この添加によってインク組成物の記録媒体への浸透性を向上することができ、種々の記録媒体においてにじみの少ない印刷を期待することができる。本発明で用いるブラックインク組成物において用いられるアセチレングリコール系界面活性剤の好ましい具体例としては、一般式（３）：
【化７】

〔式中、０≦ｍ＋ｎ≦５０であり、Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４はそれぞれ独立してアルキル基、好ましくは炭素数６以下のアルキル基である〕で表わされる化合物を挙げることができる。
【００４１】
前記一般式（３）で表される化合物の中で、特に好ましくは２，４，７，９−テトラメチル−５−デシン−４，７−ジオール、３，６−ジメチル−４−オクチン−３，６−ジオール、３，５−ジメチル−１−ヘキシン−３オールなどを挙げることができる。前記一般式（２）で表されるアセチレングリコール系界面活性剤として市販品を利用することも可能であり、その具体例としてはサーフィノール１０４、８２、４６５、４８５、又はＴＧ（いずれもＡｉｒ Ｐｒｏｄｕｃｔｓ ａｎｄ Ｃｈｅｍｉｃａｌｓ．Ｉｎｃ．より入手可能）、オルフインＳＴＧ、オルフインＥ１０１０（いずれも日信化学社製の商品名）を挙げることができる。
【００４２】
本発明で用いるブラックインク組成物は、一般式（４）：
【化８】

（式中、Ｒ^１１〜Ｒ^１７は、独立して、Ｃ_１−６アルキル基を表し、ｊ及びｋは、独立して、１以上の整数を表し、ＥＯはエチレンオキシ基を表し、ＰＯはプロピレンオキシ基を表し、ｓ及びｔは０以上の整数を表すが、但しｓ＋ｔは１以上の整数を表し、ＥＯ及びＰＯは、［ ］内においてその順序は問わず、ランダムであってもブロックであってもよい）
で表されるシリコーン系界面活性剤を含むのが好ましい。この添加によってインク組成物の記録媒体への浸透性を向上することができる。
【００４３】
前記一般式（４）で表されるシリコーン系界面活性剤において好ましい化合物は、前記一般式（４）において、Ｒ^１１〜Ｒ^１７が、独立して、Ｃ_１−６アルキル基、より好ましくはメチル基であり、ｊ及びｋが、独立して、１以上の整数、より好ましくは１〜２であり、ｓ及びｔは０以上の整数を表すが、但しｓ＋ｔが１以上の整数、より好ましくはｓ＋ｔは２〜４である化合物である。
【００４４】
前記一般式（４）で表されるシリコーン系界面活性剤において特に好ましい化合物は、前記式（４）において、ｊ及びｋが同じ数であり、しかも１〜３、特には１又は２である化合物であり、更に好ましい前記一般式（４）で表される化合物は、Ｒ^１１〜Ｒ^１７が全てメチル基を表し、ｊが１を表し、ｋが１を表し、ｕが１を表し、ｓが１以上の整数、特には１〜５の整数を表し、ｔが０を表す化合物である。
【００４５】
前記一般式（４）で表されるシリコーン系界面活性剤の添加量は適宜決定されてよいが、本発明で用いるブラックインク組成物の全重量に対して０．０３〜３重量％が好ましく、より好ましくは０．１〜２重量％程度であり、更に好ましくは０．３〜１重量％程度である。
【００４６】
前記一般式（４）で表されるシリコーン系界面活性剤は市販されており、それを利用することが可能である。例えば、ビックケミー・ジャパン株式会社より市販されているシリコーン系界面活性剤ＢＹＫ−３４７又はＢＹＫ−３４８が利用可能である。
【００４７】
インクジェット記録用水系ブラックインク組成物に含有される界面活性剤量は特に限定されるものではないが、好ましくは０．０１〜１０重量％、より好ましくは０．１〜５重量％の範囲である。界面活性剤の含有量が０．０１重量％未満になると界面活性効果が十分に得られず、１０重量％を超えると結晶の析出、液晶の形成、あるいは顔料の安定性低下などによる吐出不良の原因となる場合が認められる。
本発明において、補色用着色剤は、顔料又は染料であることができる。顔料は、顔料を分散させる分散剤によりインク組成物中に分散されるものである。
本発明の好ましい態様によれば、これらの顔料は、分散剤で水性媒体中に分散させて得られた顔料分散液としてインク組成物に添加されるのが好ましい。
分散剤としては、慣用の界面活性剤の他、顔料分散液を調製するのに慣用されている分散剤、例えば高分子分散剤を好適に使用することができる。なお、この顔料分散液に含まれる分散剤がインク組成物の分散剤及び界面活性剤としても機能するであろうことは当業者に明らかであろう。
【００４８】
より好ましい分散剤としては、高分子分散剤、特に樹脂分散剤を使用することができる。
高分子分散剤の好ましい例としては天然高分子が挙げられる。その具体例としては、にかわ、ゼラチン、ガゼイン、又はアルブミンなどのタンパク質類、アラビアゴム、又はトラガントゴムなどの天然ゴム類、サボニンなどのグルコシド類、アルギン酸、あるいはアルギン酸プロピレングリコールエステル、アルギン酸トリエタノールアミン、又はアルギン酸アンモニウムなどのアルギン酸誘導体、メチルセルロース、カルボキシメチルセルロース、ヒドロキシエチルセルロース、又はエチルヒドロキシセルロースなどのセルロース誘導体などが挙げられる。
【００４９】
また、高分子分散剤の好ましい例としては合成高分子も挙げられる。その具体例としては、ポリビニルアルコール類、ポリビニルピロリドン類、ポリアクリル酸、アクリル酸−アクリルニトリル共重合体、アクリル酸塩−アクリルニトリル共重合体、酢酸ビニル−アクリル酸エステル共重合体、又はアクリル酸−アクリル酸エステル共重合体などのアクリル系樹脂、スチレン−アクリル酸共重合体、スチレン−メタクリル酸共重合体、スチレン−メタクリル酸−アクリル酸エステル共重合体、スチレン−α−メチルスチレン−アクリル酸共重合体、又はスチレン−α−メチルスチレン−アクリル酸−アクリル酸エステル共重合体などのスチレン−アクリル樹脂、スチレン−マレイン酸共重合体、スチレン−無水マレイン酸共重合体、イソブチレン−マレイン酸樹脂、ロジン変性マレイン酸樹脂、ビニルナフタレン−アクリル酸共重合体、ビニルナフタレン−マレイン酸共重合体、あるいは、酢酸ビニル−エチレン共重合体、酢酸ビニル−脂肪酸ビニルエチレン共重合体、酢酸ビニル−マレイン酸エステル共重合体、酢酸ビニル−クロトン酸共重合体、又は酢酸ビニル−アクリル酸共重合体などの酢酸ビニル系共重合体及びそれらの塩が挙げられる。
これらの中でも、スチレン−アクリル酸共重合体、スチレン−メタクリル酸共重合体、アクリル酸−アクリル酸エステル共重合体、及びスチレン−無水マレイン酸共重合体が該分散剤として好ましい。
【００５０】
また、樹脂分散剤としては、市販のものを使用することができ、その具体例としては、ジョンソンポリマー株式会社製、ジョンクリル６８（分子量１００００、酸価１９５）、ジョンクリル６１Ｊ（分子量１００００、酸価１９５）、ジョンクリル６８０（分子量３９００、酸価２１５）、ジョンクリル６８２（分子量１６００、酸価２３５）、ジョンクリル５５０（分子量７５００、酸価２００）、ジョンクリル５５５（分子量５０００、酸価２００）、ジョンクリル５８６（分子量３１００、酸価１０５）、ジョンクリル６８３（分子量７３００、酸価１５０）、ジョンクリルＢ−３６（分子量６８００、酸価２５０）等が挙げられる。
【００５１】
本発明のインクジェット記録用インクセットに含まれる水系ブラックインク組成物は、湿潤剤、乾燥速度調整剤、及び／又は安定化剤として、水溶性有機溶媒を含有することができる。各インク組成物に添加される水溶性有機溶媒の含有量は、インク組成物の全重量に対して、好ましくは０．５〜４０重量％程度であり、より好ましくは２〜３０重量％である。
前記の水溶性有機溶媒としては、通常の水性顔料インク組成物に配合される水溶性有機溶媒を用いることができ、具体的には、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、テトラエチレングリコール、ポリエチレングリコール、ポリプロピレングリコール、プロピレングリコール、ジプロピレングリコール、ブチレングリコール、１，２，６−ヘキサントリオール、チオグリコール、ヘキシレングリコール、グリセリン、トリメチロールエタン、若しくはトリメチロールプロパンなどの多価アルコール類；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、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテル、トリエチエ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、若しくはトリエチレングリコールモノブチルエーテルなどの多価アルコールのアルキルエーテル類；あるいは、２−ピロリドン、Ｎ−メチル−２−ピロリドン、１，３−ジメチル−２−イミダゾリジノン、又はトリエタノールアミンを挙げることができる。
【００５２】
また、本発明のインクジェット記録用インクセットに含まれるブラックインク組成物は、防腐剤、金属イオン捕獲剤、及び／又は防錆剤を更に含有するのが好ましい。ここで、防腐剤は、アルキルイソチアゾロン、クロルアルキルイソチアゾロン、ベンズイソチアゾロン、ブロモニトロアルコール、オキサゾリジン系化合物、及びクロルキシレノールからなる群から選択された１種以上の化合物が好ましく、金属イオン捕獲剤は、エチレンジアミン四酢酸塩が好ましく、防錆剤は、ジシクロヘキシルアンモニウムニトラート及び／又はベンゾトリアゾールが好ましく用いられる。
【００５３】
また、本発明のインクジェット記録用インクセットに含まれるブラックインク組成物は、保存安定性の確保、目詰まり防止、吐出安定の確保、放置安定性の確保の目的で、湿潤剤、保湿剤、溶解助剤、浸透制御剤、粘度調整剤、ｐＨ調整剤、溶解助剤、酸化防止剤、防黴剤、腐食防止剤、その他の種々の添加剤を添加することができる。
その他、インク成分の溶解性を向上させ、更に記録媒体、例えば、紙に対する浸透性を向上させ、あるいはノズルの目詰まりを防止する成分として、エタノール、メタノール、ブタノール、プロパノール、又はイソプロパノールなどの炭素数１〜４のアルキルアルコール類、ホルムアミド、アセトアミド、ジメチルスルホキシド、ソルビット、ソルビタン、アセチン、ジアセチン、トリアセチン、スルホランなどを挙げることができ、これらを適宜選択して使用することができる。
【００５４】
また、ｐＨ調整剤、ジエタノールアミン、トリエタノールアミン、プロパノールアミン、モルホリンなどのアミン類及びそれらの変成物、水酸化カリウム、水酸化ナトリウム、水酸化リチウムなどの無機水酸化物、水酸化アンモニウム、４級アンモニウム塩（テトラメチルアンモニウムなど）、炭酸カリウム、炭酸ナトリウム、炭酸リチウムなどの炭酸塩類、その他、燐酸塩などを挙げることができる。
その他の添加剤として、尿素、チオ尿素、テトラメチル尿素などの尿素類、アロハネート、メチルアロハネートなどのアロハネート類、ビウレット、ジメチルビウレット、テトラメチルビウレットなどのビウレット類など、Ｌ−アスコルビン酸及びその塩、市販の酸化防止剤、紫外線吸収剤なども用いることができる。
【００５５】
また、本発明のインクジェット記録用インクセットに含まれるブラックインク組成物は、表面張力が４５ｍＮ／ｍ以下であることが好ましく、更に好ましくは、２５〜４５ｍＮ／ｍの範囲である。表面張力が４５ｍＮ／ｍを越えると、印字の乾燥性が悪くなり、滲みが発生しやすくなり、カラーブリードが発生する等のため、良好な印刷画像が得られにくい。また、表面張力が２５ｍＮ／ｍ未満では、プリンタヘッドのノズル周囲が濡れやすくなるためにインク滴の飛行曲がりが発生する等、吐出安定性に問題が生じ易い。上記表面張力は、通常に用いられる表面張力計によって測定することができる。
インクの表面張力は、インクを構成する各成分の種類や組成比などを調整することにより上記範囲内とすることができる。
本発明のインクジェット記録用インクセットに含まれるブラックインク組成物は、通常の方法で調製することができる。
本発明のインクセットは、モノクロ記録用のインクセット又はカラー記録用のインクセットであることができる。
【００５６】
本発明のモノクロ記録用インクセットは、補色用着色剤含有ブラックインク組成物（１種またはそれ以上）と補色用着色剤不含ブラックインク組成物との組み合わせの少なくとも１組を含み、各組において、前記補色用着色剤含有ブラックインク組成物と前記補色用着色剤不含ブラックインク組成物のカーボンブラック濃度がそれぞれ実質的に同濃度である。前記の或る１組の組み合わせ内部において、補色用着色剤含有ブラックインク組成物２種以上を用いる場合は、その補色用着色剤の含有量が相互に異なる。また、１つのインクセットにおいて前記の組み合わせを２組以上併用する場合は、各組相互のカーボンブラック濃度がそれぞれ異なる。
【００５７】
また、本発明のカラー記録用インクセットを構成するインク組成物の種類や数は、本発明による複数のブラックインク組成物をインクセット構成員として含む限り特に限定されるものではないが、典型的な本発明によるインクセットとしては、例えば、イエロー、シアン、マゼンタ、第１ブラックインク（補色用着色剤含有）、及び第２ブラックインク（補色用着色剤不含）の５色のインクセット；イエロー、シアン、マゼンタ、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、ライトシアン、及びライトマゼンタの７色のインクセット；イエロー、シアン、マゼンタ、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、ライトシアン、ライトマゼンタ、及びダークイエローの８色のインクセット；イエロー、マゼンタ、シアン、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、ライトマゼンタ、及びライトシアンの７色のインクセット；イエロー、シアン、マゼンタ、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、レッド、グリーン、及びブルーの８色のインクセット；イエロー、シアン、マゼンタ、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、オレンジ、グリーン、及びブルーの８色のインクセット；並びにイエロー、マゼンタ、シアン、第１ブラックインク（補色用着色剤含有）、第２ブラックインク（補色用着色剤不含）、オレンジ、グリーン、及びバイオレットの８色のインクセット；あるいは、前記の各インクセットに更に別のブラックインク組成物を含むインクセット；を挙げることができる。
なお、本発明のインクセットには、前記補色用着色剤の含有量が異なる２種以上の補色剤含有ブラックインク組成物を含む、前記カラーインクセット及び前記モノクロインクセットも含まれる。
【００５８】
なお、本明細書において「ライトマゼンタ」及び「ライトシアン」の各インク組成物とは、一般的には、濃度変調による印刷画像の画質向上を目的に、それぞれマゼンタインク組成物、及びシアンインク組成物の色材濃度を低くしたインク組成物である。また、「ダークイエロー」のインク組成物とは、シャドー部等の暗色に対する色再現性を向上させる目的で、イエローインク組成物よりも明度・彩度の低い色材（顔料）を用いたイエローインク組成物である。そして、「レッド」、「オレンジ」、「グリーン」、「ブルー」、及び「バイオレット」の各インク組成物は、色再現範囲を向上させるために、イエロー、マゼンタ、シアンの中間色を構成する要素として使用されるインク組成物である。
【００５９】
本発明のインクセットは、補色用着色剤含有ブラックインク組成物がカーボンブラックと前記補色用着色剤とを含有することを除けば、それ以外の点では、従来公知のインクセットと同様に構成することができ、従来公知の各種の記録方法用インクとして利用することができる。好ましいインクセットは、水系であり、特にインクジェット記録用インクセットである。
また、本発明の記録方法は、インク組成物の液滴を吐出して、前記液滴を記録媒体に付着させて印刷を行う記録方法であって、本発明のインクセットを用いる。ここで、記録方法は、本発明のインクセットが収容されたインクカートリッジ（各ブラックインク組成物が個別に収容されたインクカートリッジ）を公知のインクジェット記録装置に搭載させて、記録媒体に対して印刷することにより、好適に行うことができる。
ここで、インクジェット記録装置としては、電気信号に基づいて振動可能な電歪素子が搭載されるとともに、前記電歪素子の振動によって、本発明に係るインクセットが含むインクを吐出することができるように構成されたインクジェット記録装置が好ましい。
また、インクセットを収容するインクカートリッジ（収容ケース）としては、公知のものを好適に使用することができる。
また、本発明の記録物は、本発明の記録方法によって印刷されるので、カーボンブラックの帯色性を修正することができ、色味が良好である。
【００６０】
【実施例】
以下、実施例によって本発明を具体的に説明するが、これらは本発明の範囲を限定するものではない。以下の実施例及び比較例で、ｗｔ％は重量％である。
【比較例】
（１）ブラックインク組成物の調製
以下の表１に記載の配合成分を混合し、サンドミル（安川製作所製）中でガラスビーズ〔直径＝１．７ｍｍ；混合物の１．５倍量（重量）〕とともに２時間分散させ、濃いブラックインク組成物Ａ１及びＢ１、並びに薄いブラックインク組成物Ａ２及びＢ２を得た。水溶性樹脂としてはスチレン−アクリル酸共重合体（分子量＝１５０００；酸価＝１００）を用いた。なお、表１における単位は、重量％である。
【００６１】
【表１】

【００６２】
（２）グレースケールの出力
前項（１）で調製した濃いブラックインク組成物Ａ１又は薄いブラックインク組成物Ａ２をインクジェットプリンタ（ＭＣ２０００；セイコーエプソン株式会社製）の専用カートリッジのブラックインク室に充填し、専用記録媒体（ＭＣ写真用紙；セイコーエプソン株式会社製）に吐出し、それぞれ白から黒へのグレーの階調パターン（グレースケール）を、階調を１７等分に分割して出力した。出力は各インクの吐出量を分配して行った。出力されたパターンは分光光度計（ＧＲＥＴＡＧ ＳＰＭ；ＧＲＥＴＡＧ社製）を用いて測定し、ＣＩＥで規定されている色差表示法のＬ＊ａ＊ｂ＊表色系の座標を求めた。その際の条件は、光源Ｄ５０、光源フィルタなしで、白色標準は絶対白とし、視野角は２°とした。
結果を、図６の曲線ａ１（濃いブラックインク組成物Ａ１）及び曲線ａ２（薄いブラックインク組成物Ａ２）に示す。
【００６３】
また、図６の曲線ａ１と曲線ａ２とにおいて、単位面積あたりのカーボンブラック担持量が同量になる点を３箇所示す。すなわち、曲線ａ１上の点ｓ１と曲線ａ２上の点ｓ２とは、単位面積あたりのカーボンブラック担持量が同量であり、同様に、曲線ａ１上の点ｔ１と曲線ａ２上の点ｔ２、及び曲線ａ１上の点ｕ１と曲線ａ２上の点ｕ２とは、それぞれ単位面積あたりのカーボンブラック担持量が同量である。これらの各点間距離（ΔＣ^＊）を式（１）：
【数１】

によって計算した。なお、Δａ^＊は、各点間のａ^＊値の差であり、Δ^＊は、各点間のｂ^＊値の差である。結果は以下の通りであった。
ｓ１−ｓ２間距離＝８．９
ｔ１−ｔ２間距離＝５．８
ｕ１−ｕ２間距離＝０．９８
【００６４】
同様に、前項（１）で調製した濃いブラックインク組成物Ｂ１又は薄いブラックインク組成物Ｂ２をインクジェットプリンタ（ＭＣ２０００；セイコーエプソン株式会社製）の専用カートリッジのブラックインク室に充填し、専用記録媒体（光沢フィルム；セイコーエプソン株式会社製）に吐出し、白から黒へのグレーの階調パターン（グレースケール）を、階調を１７等分に分割して出力した。出力は各インクの吐出量を分配して行った。出力されたパターンを測色し、ａ＊，ｂ＊座標をプロットした。濃いブラックインク組成物Ｂ１からは、図６の曲線ａ１と同様のグレースケール軌跡が得られ、薄いブラックインク組成物Ｂ２からは、図６の曲線Ａ２と同様のグレースケール軌跡が得られた。
【００６５】
図６から明らかなとおり、補色用着色剤を添加しない場合には、濃いブラックインク組成物及び薄いブラックインク組成物のそれぞれから得られるグレースケール軌跡は、原点から大幅に乖離し、帯色性を示す。
【００６６】
（実施例１及び２）
（１）ブラックインク組成物の調製
以下の表２に記載の配合成分を混合し、サンドミル（安川製作所製）中でガラスビーズ〔直径＝１．７ｍｍ；混合物の１．５倍量（重量）〕とともに２時間分散させ、補色用着色剤含有ブラックインク組成物Ｘ１及びＹ１、並びに補色用着色剤不含ブラックインク組成物Ｘ２及びＹ２を得た。水溶性樹脂としてはスチレン−アクリル酸共重合体（分子量＝１５０００；酸価＝１００）を用いた。なお、表２における単位は、重量％である。
【００６７】
【表２】

【００６８】
（２）グレースケールの出力（インクセットＸ：実施例１）
補色用着色剤含有ブラックインク組成物Ｘ１及び補色用着色剤不含ブラックインク組成物Ｘ２からインクセットＸ（実施例１）を構成し、インクジェットプリンタ（ＭＣ２０００；セイコーエプソン株式会社製）の専用カートリッジに、次のように充填した。
（イ）前記インクジェットプリンタ（ＭＣ２０００）のインクカートリッジのブラックインク室に補色用着色剤含有ブラックインク組成物Ｘ１を充填した。
（ロ）前記インクジェットプリンタ（ＭＣ２０００）のインクカートリッジのシアンインク室に補色用着色剤不含ブラックインク組成物Ｘ２を充填した。
専用記録媒体（ＭＣ写真用紙；セイコーエプソン株式会社製）に吐出し、それぞれ白から黒へのグレーの階調パターン（グレースケール）を、階調を１８等分に分割して出力した。出力は各インクの吐出量を分配して行った。出力されたパターンは分光光度計（ＧＲＥＴＡＧ ＳＰＭ；ＧＲＥＴＡＧ社製）を用いて測定し、ＣＩＥで規定されている色差表示法のＬ＊ａ＊ｂ＊表色系の座標を求めた。その際の条件は、光源Ｄ５０、光源フィルタなしで、白色標準は絶対白とし、視野角は２°とした。本実施例では、白（階調１７）から黒（階調０）の１８階調のうち、階調１７〜１６を補色用着色剤不含ブラックインク組成物Ｘ２で印刷し、階調１５〜０を補色用着色剤含有ブラックインク組成物Ｘ１で印刷した。結果を、図７に示す。
【００６９】
（３）グレースケールの出力（インクセットＹ：実施例２）
補色用着色剤含有ブラックインク組成物Ｙ１及び補色用着色剤不含ブラックインク組成物Ｙ２からインクセットＹ（実施例２）を構成し、インクジェットプリンタ（ＭＣ２０００；セイコーエプソン株式会社製）の専用カートリッジに、次のように充填した。
（イ）前記インクジェットプリンタ（ＭＣ２０００）のインクカートリッジのブラックインク室に補色用着色剤含有ブラックインク組成物Ｙ１を充填した。
（ロ）前記インクジェットプリンタ（ＭＣ２０００）のインクカートリッジのシアンインク室に補色用着色剤不含ブラックインク組成物Ｙ２を充填した。
専用記録媒体（ＭＣ写真用紙；セイコーエプソン株式会社製）に吐出し、それぞれ白から黒へのグレーの階調パターン（グレースケール）を、階調を１８等分に分割して出力した。出力は各インクの吐出量を分配して行った。出力されたパターンは分光光度計（ＧＲＥＴＡＧ ＳＰＭ；ＧＲＥＴＡＧ社製）を用いて測定し、ＣＩＥで規定されている色差表示法のＬ＊ａ＊ｂ＊表色系の座標を求めた。その際の条件は、光源Ｄ５０、光源フィルタなしで、白色標準は絶対白とし、視野角は２°とした。本実施例では、白（階調１７）から黒（階調０）の１８階調のうち、階調１７及び階調６〜０を補色用着色剤不含ブラックインク組成物Ｙ２で印刷し、階調１６〜７を補色用着色剤含有ブラックインク組成物Ｙ１で印刷した。結果を、図８に示す。
【００７０】
【発明の効果】
本発明によれば、中間階調の灰色や濃灰色に発生する帯色性を適切に修正することのできるインクセットが提供される。
【図面の簡単な説明】
【図１】ＣＩＥで規定されている色差表示法のＬ＊ａ＊ｂ＊表色系のａ＊，ｂ＊座標にプロットしたグレースケール軌跡を模式的に示す説明図である。
【図２】薄いブラックインク〔図２（１）〕又は濃いブラックインク〔図２（２）〕を用いて、同じ灰色を表現するのに必要な量のカーボンブラックが、記録媒体表面の単位面積あたりに付着するようにデューティーを調節してインク液滴を吐出させる状態を模式的に示す説明図である。
【図３】ＣＩＥで規定されている色差表示法のＬ＊ａ＊ｂ＊表色系のａ＊，ｂ＊座標にプロットした濃いブラックインクのグレースケール軌跡に、薄いブラックインクの仮想グレースケール軌跡が重なることを模式的に示す説明図である。
【図４】図１の曲線ｄのグレースケール軌跡を示す濃いブラックインクにおいて、補色用着色剤含有インク組成物と補色用着色剤不含インク組成物との諧調分割方法を模式的に示す説明図である。
【図５】図１の曲線ｅのグレースケール軌跡を示す薄いブラックインクにおいて、補色用着色剤含有インク組成物と補色用着色剤不含インク組成物との諧調分割方法を模式的に示す説明図である。
【図６】比較例にて作成した濃いブラックインクと薄いブラックインクの実際のグレースケール軌跡をａ＊，ｂ＊座標に示すグラフである。
【図７】実施例１にて作成したインクセットＸの実際のグレースケール軌跡をａ＊，ｂ＊座標に示すグラフである。
【図８】実施例２にて作成したインクセットＹの実際のグレースケール軌跡をａ＊，ｂ＊座標に示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an ink set containing at least two combinations of a black ink composition having the same carbon black concentration but one containing a colorant for a complementary color and the other containing no colorant for a complementary color, and the ink. The present invention relates to a recording method using a set, a recorded matter, and an ink jet recording apparatus.
[0002]
[Prior art]
When an image is formed by an ink jet recording method or the like, an ink set including a light black ink may be used in order to obtain a high-quality image. For example, a four-color ink set including a black ink, a cyan ink, a magenta ink, and a yellow ink (or a six-color ink set in which a light cyan ink and a light magenta ink are added thereto) is added to a five-color ink set. Set (or a seven-color ink set). The light black ink has a lower carbon black density than the black ink, and is used for the purpose of improving color reproducibility for dark colors such as shadow portions and gray gradation.
[0003]
However, since the light black ink (that is, the light black ink) has a low carbon black content, the resulting hue is not an achromatic color originally required but a tint. That is, in the L * a * b * space of the color difference display method defined by the CIE (International Commission on Illumination), it deviates from (a *, b *) = (0, 0), and specifically, yellowish It takes on. To correct such yellowness of carbon black, it is necessary to use a colorant (eg, a pigment) that is a complementary color of yellow.
For example, US Pat. No. 5,803,958 (Patent Document 1) describes a black pigment ink composition containing a cyan pigment and a magenta pigment in addition to carbon black. That is, the same effect as when a blue pigment is added is obtained by mixing a cyan pigment and a magenta pigment, and when this black pigment ink composition is used as a light black ink composition, the yellowing property is improved. It is assumed.
[0004]
On the other hand, it is known that even with a black ink having a high carbon black content (that is, a dark black ink), the obtained hue becomes reddish instead of the originally required achromatic color. As means for correcting such reddishness, for example, JP-A-64-180 (Patent Document 2) describes a method of adding a copper phthalocyanine pigment.
However, a detailed report on the relationship between the yellowish and reddish properties and the carbon black content as described above has not been known until now, and the yellowish property in a thin black ink and the reddish property in a dark black ink have not been reported. A technique for simultaneously correcting the gender has not been proposed in the prior art.
[0005]
Also, an ink jet recording method using two or more types of black inks having different carbon black concentrations is known, and it is also known to add another type of dye or pigment to the high-concentration black ink and the low-concentration black ink ( JP-A-11-48502: Patent Document 3). However, the dyes or pigments to be added to each of these black inks are only described as using a black dye alone or as a mixture, or using a mixture of yellow, magenta, and cyan. There is no description suggesting a means for simultaneously correcting yellowishness and reddishness.
[0006]
Further, in the case where a gray scale (a plurality of gradation patterns from white to black via gray) is formed using one kind of black ink composition containing a specific concentration of carbon black, recording is performed. Since the amount of carbon black to be carried on the medium surface needs to be adjusted stepwise from a small amount to a large amount, the ejection amount of the ink droplet is changed from a low duty to a high duty. Even in such a case, as described later, banding occurs particularly in grays of intermediate gradation in black ink having a high carbon black content, and particularly in the case of black ink having a low carbon black content. The present inventor has found that banding occurs in dark gray. The phenomenon itself of the banding in such a half-tone gray or dark gray has not been known in the past, and therefore no solution has been known.
[0007]
[Patent Document 1]
U.S. Pat. No. 5,803,958
[Patent Document 2]
JP-A-64-180
[Patent Document 3]
JP-A-11-48502
[0008]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a black ink composition containing carbon black, which appropriately corrects the banding that occurs in a medium-gray-gray record or a medium-gray to dark-gray record. Is provided.
[0009]
[Means for Solving the Problems]
Therefore, the present invention includes a first black ink composition containing carbon black and a colorant for complementary color, and carbon black at a concentration substantially equal to the concentration of carbon black in the first black ink composition. Comprises at least one combination with a second black ink composition containing no complementary colorant.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the principle of the present invention will be described.
As will be specifically shown in a comparative example described later, the present inventors first set the carbon content in an ink set for ink jet recording at a high content similar to that of a black ink generally used as a dark black ink. A dark black ink containing black is prepared, a gray scale (18-step gradation pattern from white to black via gray) is created, each gradation is measured, and the color difference display method specified by CIE When plotted on the a * and b * coordinates of the L * a * b * color system, a gray scale locus schematically shown by a curve d in FIG. 1 was drawn.
[0011]
In the a * and b * coordinates shown in FIG. 1, the intersection between the a * axis and the b * axis, that is, the origin (a * = 0 and b * = 0) is achromatic, and from the origin, for example, the b * axis If the distance increases in the + (plus) direction (Y direction in FIG. 1), the yellowishness increases in accordance with the degree of the distance. If the distance increases in the opposite-(minus) direction (the direction B in FIG. 1), the yellowness increases. , Blue taste becomes stronger. Also, as the distance from the origin in the direction of the broken line C in FIG. 1 increases, the cyan taste increases. Similarly, as the distance from the origin in the direction of the broken line M in FIG. 1 increases, the magenta taste increases. Further, broken lines G and R in FIG. 1 indicate the directions of green and red, respectively.
[0012]
That is, the gray scale locus of the curve d in FIG. 1 draws a locus colored from the achromatic white (a * = 0 and b * = 0) in the direction of the arrow D as the gray becomes darker. Eventually, it returned to the vicinity of achromatic black (a * = 0 and b * = 0). (Actually measured data does not return exactly to the origin indicating ideal black, but in FIG. 1, It is schematically shown as returning to the origin).
[0013]
Subsequently, the present inventors prepared a thin black ink containing carbon black in the same low content as the black ink generally used as a thin black ink in the ink set for ink jet recording, A gray scale (18 gradation patterns) similar to that described above was created, each gradation was measured, and plotted on the a * and b * coordinates of the L * a * b * color system.
[0014]
As schematically shown in FIG. 2, when a specific gray is expressed by a light black ink [FIG. 2 (1)] or a dark black ink [FIG. 2 (2)], the specific gray is expressed. Ink droplets are ejected so that the necessary amount of carbon black adheres to the recording medium surface 1 per unit area. For example, as shown in FIG. 2A, when a thin black ink is used, since the content of the carbon black 2e in each ink droplet is small, it is necessary to print at a high duty. On the other hand, as shown in FIG. 2 (2), when the same gray is expressed using dark black ink, it is necessary to print at a low duty because the content of carbon black 2d in each ink droplet is large. There is.
[0015]
In any of these cases, the amount of carbon black carried per unit area is the same, so that the gray scale created from the thin black ink overlaps the gray scale locus of curve d in FIG. Should draw a locus indicated by a thick line e ′. That is, from the white (a * = 0 and b * = 0) at the 0% duty point to the 100% duty point (the tip x of the thick line e '), the gray scale of the thick line e' in the direction of the arrow E ' It should draw a trajectory.
[0016]
However, surprisingly, the actual gray scale trajectory is the curve e in FIG. 1, which is significantly shifted to the yellow side from the expected gray scale trajectory (thick line e ′ in FIG. 3). That is, it was found that a locus was drawn from the white color (a * = 0 and b * = 0) at the 0% duty point to the 100% duty point (the tip y of the thin line e) along the direction of arrow E.
[0017]
Summarizing the above results, when a gray scale is created with dark black ink, as shown by curve d in FIG. 1, light gray (the number of ink droplets ejected per unit area on a recording medium is relatively small, When the amount of carbon black per unit area is small; when the duty is low, the color takes on a hue between yellow and red, and dark gray (the number of ink droplets ejected per unit area on the recording medium is relatively large) (When the amount of carbon black per unit area is large; when the duty is high), it tends to take on a red hue. On the other hand, when a gray scale is created with a thin black ink, as shown by a curve e in FIG. 1, there is a tendency that the expected gray scale locus (thick line e ′ in FIG. 3) shifts to the yellow side.
[0018]
In the dark black ink, the deviation from the achromatic color is particularly conspicuous in the intermediate gradation, and in the thin black ink, the deviation from the achromatic color is conspicuous in the intermediate gradation and the dark gradation. That is, when a gray scale is created with dark black ink, banding is hardly recognized in gray close to white and gray close to black, but banding is recognized in gray of intermediate gradation. Further, when a gray scale is created with a thin black ink, banding is hardly recognized in gray close to white, but banding is recognized in gray of intermediate to high density.
[0019]
The reason why such a phenomenon occurs depending on the difference in the carbon black content and the duty in the black ink is unknown to the present inventors and others. not exist. Therefore, for example, a technique for correcting the banding property (reddish property) that occurs when printing a halftone gray using dark black ink as shown by the locus of the curve d in FIG. unknown. Further, for example, there is also a technique for correcting the banding (yellowing) that occurs when printing a halftone gray or dark gray using a thin black ink as shown by the locus of the curve e in FIG. Conventionally, it is not known at all. Further, in an ink set using both a dark black ink and a light black ink as shown in FIG. 1, a technique for appropriately correcting the banding property, that is, the reddish property and the yellowish property, has not been known at all. Not.
The present invention provides a means for appropriately correcting the above-mentioned drawbacks by utilizing the above-mentioned phenomenon found by the present inventors.
[0020]
That is, according to the present invention, when a gray scale is prepared using a black ink composition containing only carbon black as a colorant, the L * a * b color difference display method defined by the CIE (International Commission on Illumination) is used. * In a gray scale locus drawn in space, only carbon black is used for a black ink composition for recording a gradation that does not deviate from the origin (a *, b * = 0, 0). A black ink composition for recording a gradation that is chromatically deviated relatively largely from the origin (a *, b * = 0, 0) includes a colorant for a complementary color that is a complementary color of the chromatic color. To correct chromatic coloring. Therefore, the ink set of the present invention has at least one combination of a pair of two types of black ink compositions having the same carbon black concentration but one containing a colorant for complementary color and the other containing no colorant for complementary color. Black ink set.
[0021]
For example, when a dark gray color is recorded as in a dark black ink composition that draws a gray scale locus like a curve d in FIG. 1, the intersection of the a * axis and the b * axis, that is, the origin (a * = 0) And b * = 0), a high-concentration carbon black black ink composition that returns to the vicinity of (1) a first black ink composition for gray-scale gray recording and (2) a light gray The first black ink composition is divided into a second black ink composition for recording and a dark gray recording, and a colorant for complementary color is contained in the first black ink composition. Does not contain a colorant for complementary colors. The carbon black concentration is substantially the same in the first black ink composition and the second black ink composition. The colorant for a complementary color contained in the black ink composition containing a colorant for a complementary color can be selected and added as a colorant that is a complementary color of the gray scale locus d (the colorant in the region cD in FIG. 1).
[0022]
On the other hand, when a dark gray color is recorded as in a thin black ink composition that draws a gray scale locus like a curve e in FIG. 1, the intersection of the a * axis and the b * axis, that is, the origin (a * = 0) And b * = 0), a low-concentration carbon black black ink composition that terminates at a point far away from (b) = 0) is used: (1) a first black ink composition for medium-tone gray recording and dark gray recording And (2) a second black ink composition for light gray recording, wherein the first black ink composition contains a complementary colorant. The product does not contain a complementary colorant. The carbon black concentration is substantially the same in the first black ink composition and the second black ink composition. The colorant for a complementary color contained in the black ink composition containing a colorant for a complementary color can be selected and added as a colorant that becomes a complementary color of the gray scale locus e (the colorant in the region cE in FIG. 1).
[0023]
Further, the ink set according to the present invention may include a set composed of a combination of two or more kinds of black ink compositions containing a colorant for complementary colors and one kind of black ink composition containing no colorant for complementary colors. That is, in a certain set of black inks used in the ink set of the present invention, the carbon black content contained in each black ink composition belonging to the set is made substantially the same, and the black ink composition containing the colorant for complementary color is used. As a product, two or more kinds of black ink compositions containing a complementary colorant containing the same kind of complementary colorant in different contents can be used in combination.
[0024]
Further, in the ink set according to the present invention, the number of combinations of the combination of the complementary colorant-containing black ink composition and the complementary colorant-free black ink composition having substantially the same carbon black concentration is as follows. There is no particular limitation as long as at least one set is included, and a plurality of sets of two or more combinations having mutually different carbon black concentrations can be included. Further, in addition to a set of combinations having the same concentration of carbon black, a combination of one or more black ink compositions having different carbon black concentrations and containing no or containing a colorant for complementary color can be used. .
[0025]
For example, a combination of a dark black ink composition that draws a gray scale locus as shown by a curve d in FIG. 1 and a set of thin black ink composition that draws a gray scale locus as shown by a curve e in FIG. it can. In that case, as an ink set,
(A1) a dark black ink composition containing no colorant for complementary color, and
(A2) Dark black ink composition containing a complementary colorant
In addition to the combination (set of the same carbon black concentration),
(B1) a thin black ink composition containing no complementary colorant,
(B2) Thin black ink composition containing a colorant for complementary color
Or the same combination (set of the same carbon black concentration), or
(B1) a thin black ink composition containing no colorant for complementary color or
(B2) Thin black ink composition containing a colorant for complementary color
The ink set can include:
[0026]
Or
(A1) a thin black ink composition containing no colorant for complementary color, and
(A2) Thin black ink composition containing a colorant for complementary color
In addition to the combination (set of the same carbon black concentration),
(B1) a dark black ink composition containing no complementary colorant;
(B2) Dark black ink composition containing a colorant for complementary color
(The same set of carbon black concentrations) or
(B1) a dark black ink composition containing no complementary colorant or
(B2) Dark black ink composition containing a colorant for complementary color
The ink set can include:
[0027]
In the ink set of the present invention, an appropriate complementary colorant for a black ink composition containing a certain concentration of carbon black can be selected, for example, by the following procedure. That is, as described above, a gray scale is created for a black ink composition containing only carbon black, each gradation is measured, and the L * a * b * color specification of the color difference display method specified by the CIE is used. Plot the a *, b * coordinates of the system and draw the gray scale trajectory in the first quadrant of the a *, b * coordinates, with respect to the origin of the gray scale trajectory (a * = 0 and b * = 0). A point-symmetric virtual locus is drawn in the third quadrant of the a * and b * coordinates, a colorant having a hue overlapping with the hue of the virtual locus is determined, and the colorant is selected as a complementary colorant.
[0028]
The present inventor specifically searched for an appropriate complementary colorant by the above-described procedure. For example, the ink set of the present invention has a relatively low carbon black concentration, and has a curve e in FIG. When a thin black ink composition that draws a gray scale trajectory is included, a black ink composition containing a complementary colorant for medium-tone gray recording or dark gray recording has the general formula (1):
Embedded image

(Wherein p is an integer of 0 to 3), whereby the banding in the intermediate gray to the dark gray is appropriately corrected, and the gray close to the ideal achromatic color is obtained. It turns out that scales can be created.
[0029]
Among the pigments represented by the formula (1), the compound in the case of p = 0 is known as Color Index Pigment Blue 60 (CIPB60). In the case of such a thin black ink composition, the carbon black content in the colorant-free black ink composition for a complementary color (and the black ink composition containing a colorant for a complementary color) is based on the total weight of each black ink composition. , 0.01 to 10% by weight, preferably 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, represented by the general formula (1) in the black ink composition containing a colorant for complementary color. The content of the pigment is 0.01 to 5% by weight, preferably 0.01 to 3% by weight, more preferably 0.1 to 3% by weight based on the total weight of the black ink composition containing a complementary colorant. %.
[0030]
Further, when the ink set of the present invention has a relatively high carbon black concentration and includes a dark black ink composition which draws a gray scale locus as shown by a curve d in FIG. Formula (2):
Embedded image

It has been found that the addition of the pigment represented by the formula (1) appropriately corrects the banding at intermediate gradations, and can produce a gray scale close to an ideal achromatic color.
[0031]
The pigment represented by the formula (2) is a phthalocyanine blue pigment, which is known as Color Index Pigment Blue 15: 3 or Color Index Pigment Blue 15: 4. In the case of such a dark black ink composition, the carbon black content in the colorant-free black ink composition for complementary color (and the black ink composition containing colorant for complementary color) is based on the total weight of each black ink composition. , 0.01 to 10% by weight, preferably 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, and the content of the pigment represented by the general formula (2) is It is 0.01 to 5% by weight, preferably 0.01 to 3% by weight, more preferably 0.1 to 3% by weight, based on the total weight of the agent-containing black ink composition.
[0032]
The quantitative ratio between the carbon black and the complementary colorant contained in each of the complementary colorant-containing black ink compositions included in the ink set of the present invention is not particularly limited, and the coloration of each carbon black used is not limited. May be added in an amount that can correct the above. To specifically determine the content, for example, the above-described gray scale locus is created for a recorded image formed by an ink composition containing the carbon black to be used and the complementary colorant at a specific ratio. Then, the degree of correction of the banding property is evaluated, and the content ratio of the two that can appropriately correct the banding property is adjusted.
[0033]
Using the ink set of the present invention, when creating a gray scale or the like, using a complementary colorant-containing black ink composition to perform recording, and using a complementary colorant-free black ink composition The selection of the gradation to be recorded can be appropriately determined, for example, from a gray scale locus as shown in FIG. 4 or FIG. FIG. 4 is a schematic graph in which only the curve d in FIG. 1 is left and the other curve e and broken lines R, G, C, M, and the like are deleted, and FIG. 5 is similarly a curve e in FIG. 5 is a schematic graph leaving only the graph.
[0034]
In the case of the black ink composition showing the gray scale locus of the curve d in FIG. 4, for example, the origin (a * = 0 and b * = 0) and the origin in the a * and b * coordinates in FIG. The distance Q to the point R1 on the farthest curve d is calculated, and for a region whose distance from the origin (a * = 0 and b * = 0) is 0.5Q or less, the colorant-free black ink composition for a complementary color does not exist. Using the product D1, the black ink composition D2 containing the colorant for complementary color can be used in a region apart from 0.5Q. Alternatively, instead of dividing by 0.5Q, for example, it is also possible to divide into two by any value between 0.3Q to 0.7Q (or 0.4Q to 0.6Q). Alternatively, two or more types of black ink compositions containing a colorant for a complementary color, which are divided into three or more parts and have different colorant contents for a complementary color, may be used.
[0035]
Further, for example, in the case of a black ink composition showing the gray scale locus of the curve e in FIG. 5, the origins (a * = 0 and b * = 0) and the The distance Q to the point R2 on the curve e farthest from the origin is calculated, and for a region whose distance from the origin (a * = 0 and b * = 0) is 0.5Q or less, the colorant free of the colorant for complementary colors is used. The ink composition E1 can be used, and the colorant-containing black ink composition E2 for complementary colors can be used in a region apart from 0.5Q. Alternatively, instead of dividing by 0.5Q, for example, it is also possible to divide into two by any value between 0.3Q to 0.7Q (or 0.4Q to 0.6Q). Alternatively, it can be divided into three or more as described above.
[0036]
Examples of the carbon black used in the black ink composition of the ink set of the present invention (that is, the black ink composition containing a colorant for a complementary color and the black ink composition not containing a colorant for a complementary color) include, for example, a contact method, a furnace method, and a carbon black method. Carbon black produced by a known method such as a thermal method can be used. Specific examples of the carbon black include No. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No. 2200B, etc .; Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 1700, etc., manufactured by Columbia Corporation; Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW2V, Color Black FW2V, Color Black FW2, Color Black FW2V 0, Color BlackS160, Color Black S170, Printex 35, Printex U, can be used Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, the Special Black 4 and the like. The particle size of the carbon black is not particularly limited, but is preferably 10 μm or less, and more preferably 0.1 μm or less.
In the same ink set, the carbon black contained in each black ink composition belonging to the same set has the same concentration, and the carbon black concentration contained in each black ink composition belonging to another set is different from each other.
[0037]
The complementary colorant-free black ink composition included in the ink set of the present invention can contain the same compounding component as a conventionally known black ink composition, and the complementary colorant-containing black ink composition includes the above-described black ink composition. Except for containing a colorant for complementary colors, other than that, it can contain the same compounding components as the conventionally known black ink composition, and each can be prepared as an organic ink or preferably an aqueous ink. Can be. Further, the ink set of the present invention can be used as conventionally known inks for various recording methods, and can be preferably used as ink sets for inkjet recording.
Hereinafter, the case where the ink set of the present invention is for inkjet recording and each ink composition is a water-based ink composition will be briefly described.
[0038]
In the aqueous black ink composition for inkjet recording, the carbon black and the colorant for complementary colors are preferably added to the ink composition as a pigment dispersion liquid dispersed in an aqueous medium with a dispersant.
[0039]
The aqueous black ink composition for inkjet recording used in the ink set of the present invention can further contain a surfactant. Specific examples of the surfactant include an anionic surfactant (for example, sodium dodecylbenzenesulfonate, sodium laurate, or an ammonium salt of polyoxyethylene alkyl ether sulfate), a nonionic surfactant (for example, polyoxyethylene). Ethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, or polyoxyethylene alkylamide, etc., an amphoteric surfactant (for example, N, N- Dimethyl-N-alkyl-N-carboxymethylammonium betaine, N, N-dialkylaminoalkylene carboxylate, N, N, N-trialkyl-N-sulfoalkylene ammonium betain , N, N-dialkyl-N, N-bispolyoxyethyleneammonium sulfate betaine or 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine) and the like, and these are used alone. Or a combination of two or more.
[0040]
The black ink composition according to the present invention preferably contains an acetylene glycol-based surfactant. By this addition, the permeability of the ink composition into the recording medium can be improved, and printing with little bleeding on various recording media can be expected. Preferred specific examples of the acetylene glycol-based surfactant used in the black ink composition used in the present invention include general formula (3):
Embedded image

[Wherein 0 ≦ m + n ≦ 50, and R ¹ , R ² , R ³ , And R ⁴ Are each independently an alkyl group, preferably an alkyl group having 6 or less carbon atoms].
[0041]
Among the compounds represented by the general formula (3), particularly preferred are 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 3,6-dimethyl-4-octyne-3. , 6-diol, 3,5-dimethyl-1-hexyne-3ol, and the like. As the acetylene glycol-based surfactant represented by the general formula (2), a commercially available product can be used, and specific examples thereof include Surfynol 104, 82, 465, 485, and TG (all of which are Air Products). and Chemicals, Inc.), Olufin STG, and Olufin E1010 (all are trade names manufactured by Nissin Chemical Co., Ltd.).
[0042]
The black ink composition used in the present invention has a general formula (4):
Embedded image

(Where R ¹¹ ~ R ¹⁷ Is independently C _1-6 Represents an alkyl group, j and k independently represent an integer of 1 or more, EO represents an ethyleneoxy group, PO represents a propyleneoxy group, and s and t represent an integer of 0 or more, provided that s + t represents an integer of 1 or more, and EO and PO may be in any order in [] and may be random or block.
It is preferable to include a silicone surfactant represented by the following formula. By this addition, the permeability of the ink composition into the recording medium can be improved.
[0043]
Preferred compounds in the silicone surfactant represented by the general formula (4) are those represented by R in the general formula (4). ¹¹ ~ R ¹⁷ But independently C _1-6 An alkyl group, more preferably a methyl group, j and k are independently an integer of 1 or more, more preferably 1-2, and s and t represent an integer of 0 or more, provided that s + t is 1 It is a compound in which the above integer, more preferably, s + t is 2 to 4.
[0044]
Particularly preferred compounds in the silicone surfactant represented by the general formula (4) are compounds in which j and k are the same number in the above formula (4), and are 1 to 3, especially 1 or 2. And a more preferable compound represented by the general formula (4) is R ¹¹ ~ R ¹⁷ Are all methyl groups, j represents 1, k represents 1, u represents 1, s represents an integer of 1 or more, particularly an integer of 1 to 5, and t represents 0. .
[0045]
The addition amount of the silicone-based surfactant represented by the general formula (4) may be appropriately determined, but is preferably 0.03 to 3% by weight based on the total weight of the black ink composition used in the present invention. It is more preferably about 0.1 to 2% by weight, and still more preferably about 0.3 to 1% by weight.
[0046]
The silicone surfactant represented by the general formula (4) is commercially available, and can be used. For example, a silicone surfactant BYK-347 or BYK-348 commercially available from BYK Japan KK can be used.
[0047]
The amount of the surfactant contained in the aqueous black ink composition for inkjet recording is not particularly limited, but is preferably in the range of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight. . When the content of the surfactant is less than 0.01% by weight, a sufficient surfactant effect cannot be obtained. When the content exceeds 10% by weight, ejection failure due to precipitation of crystals, formation of liquid crystal, or deterioration of pigment stability is caused. Causes are recognized.
In the present invention, the complementary colorant may be a pigment or a dye. The pigment is dispersed in the ink composition by a dispersant that disperses the pigment.
According to a preferred embodiment of the present invention, these pigments are preferably added to the ink composition as a pigment dispersion obtained by dispersing the pigment in an aqueous medium with a dispersant.
As the dispersant, besides a conventional surfactant, a dispersant commonly used for preparing a pigment dispersion, for example, a polymer dispersant can be suitably used. It will be apparent to those skilled in the art that the dispersant contained in this pigment dispersion will also function as a dispersant and a surfactant in the ink composition.
[0048]
As a more preferred dispersant, a polymer dispersant, in particular, a resin dispersant can be used.
Preferred examples of the polymer dispersant include natural polymers. Specific examples thereof include glue, gelatin, casein, or proteins such as albumin, natural gums such as gum arabic, or gum tragacanth, glucosides such as savonin, alginic acid, or propylene glycol alginate, triethanolamine alginate, or Examples include alginic acid derivatives such as ammonium alginate, and cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and ethylhydroxycellulose.
[0049]
Preferred examples of the polymer dispersant include a synthetic polymer. Specific examples thereof include polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, vinyl acetate-acrylate copolymer, or acrylic acid. -Acrylic resins such as acrylic ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid Styrene-acrylic resin such as copolymer or styrene-α-methylstyrene-acrylic acid-acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic acid resin , Rosin-modified maleic resin, vinyl naphthalene -Acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, or vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-croton An acid copolymer or a vinyl acetate-based copolymer such as a vinyl acetate-acrylic acid copolymer and salts thereof may be mentioned.
Among these, a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, an acrylic acid-acrylate copolymer, and a styrene-maleic anhydride copolymer are preferable as the dispersant.
[0050]
As the resin dispersant, commercially available resins can be used. Specific examples thereof include Joncryl 68 (molecular weight 10,000, acid value 195) and Joncryl 61J (molecular weight 10,000, acid 195), Joncryl 680 (molecular weight 3900, acid number 215), Joncryl 682 (molecular weight 1600, acid number 235), Joncryl 550 (molecular weight 7500, acid number 200), Joncryl 555 (molecular weight 5000, acid number 200) ), Joncryl 586 (molecular weight 3100, acid value 105), Joncryl 683 (molecular weight 7300, acid value 150), Joncryl B-36 (molecular weight 6800, acid value 250) and the like.
[0051]
The water-based black ink composition included in the ink set for inkjet recording of the present invention can contain a water-soluble organic solvent as a wetting agent, a drying speed adjusting agent, and / or a stabilizer. The content of the water-soluble organic solvent added to each ink composition is preferably about 0.5 to 40% by weight, more preferably 2 to 30% by weight, based on the total weight of the ink composition. .
As the water-soluble organic solvent, a water-soluble organic solvent to be blended in a general aqueous pigment ink composition can be used, and specifically, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol Polyhydric alcohols such as propylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, or trimethylolpropane; ethylene glycol mono Ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl Alkyl ethers of polyhydric alcohols such as ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, or triethylene glycol monobutyl ether; or 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3- Dimethyl-2-imidazolidinone or triethanolamine can be mentioned.
[0052]
Further, the black ink composition contained in the ink set for inkjet recording of the present invention preferably further contains a preservative, a metal ion capturing agent, and / or a rust inhibitor. Here, the preservative is preferably at least one compound selected from the group consisting of alkylisothiazolone, chloroalkylisothiazolone, benzisothiazolone, bromonitroalcohol, oxazolidine-based compound, and chlorxylenol, and the metal ion scavenger is ethylenediamine. Tetraacetic acid salts are preferable, and dicyclohexylammonium nitrate and / or benzotriazole are preferably used as the rust preventive.
[0053]
Further, the black ink composition contained in the ink set for inkjet recording of the present invention contains a humectant, a humectant, and a dissolving agent for the purpose of securing storage stability, preventing clogging, securing ejection stability, and securing storage stability. Auxiliaries, penetration control agents, viscosity adjusters, pH adjusters, dissolution aids, antioxidants, fungicides, corrosion inhibitors, and other various additives can be added.
In addition, the number of carbon atoms such as ethanol, methanol, butanol, propanol, or isopropanol as a component that improves the solubility of the ink component and further improves the permeability to a recording medium, for example, paper, or prevents nozzle clogging. Examples thereof include alkyl alcohols of 1 to 4, formamide, acetamide, dimethyl sulfoxide, sorbite, sorbitan, acetin, diacetin, triacetin, and sulfolane, and these can be appropriately selected and used.
[0054]
In addition, pH adjusters, amines such as diethanolamine, triethanolamine, propanolamine, and morpholine, and modified products thereof, inorganic hydroxides such as potassium hydroxide, sodium hydroxide, and lithium hydroxide, ammonium hydroxide, and quaternary Examples thereof include ammonium salts (such as tetramethylammonium), carbonates such as potassium carbonate, sodium carbonate, and lithium carbonate, and phosphates.
As other additives, ureas such as urea, thiourea and tetramethylurea, allohanates such as allohanate and methyl allohanate, biurets such as biuret, dimethyl biuret and tetramethyl biuret, and L-ascorbic acid and salts thereof Commercially available antioxidants and ultraviolet absorbers can also be used.
[0055]
The surface tension of the black ink composition included in the ink set for inkjet recording of the invention is preferably 45 mN / m or less, and more preferably 25 to 45 mN / m. When the surface tension is more than 45 mN / m, the drying property of the printing deteriorates, bleeding easily occurs, and color bleeding occurs, so that it is difficult to obtain a good printed image. On the other hand, if the surface tension is less than 25 mN / m, the area around the nozzles of the printer head is apt to get wet, so that the ejection stability of the ink droplets tends to be deviated. The surface tension can be measured by a commonly used surface tensiometer.
The surface tension of the ink can be controlled within the above range by adjusting the type and composition ratio of each component constituting the ink.
The black ink composition included in the ink set for inkjet recording of the present invention can be prepared by a usual method.
The ink set of the present invention can be an ink set for monochrome recording or an ink set for color recording.
[0056]
The monochrome recording ink set of the present invention includes at least one set of a combination of a colorant-containing black ink composition for complementary color (one or more types) and a colorant-free black ink composition for complementary color. The black ink composition containing the colorant for complementary color and the black ink composition not containing the colorant for complementary color have substantially the same carbon black concentration. When two or more types of black ink compositions containing a complementary colorant are used within a certain combination, the contents of the complementary colorants are different from each other. When two or more of the above combinations are used in one ink set, the carbon black concentrations of the respective sets are different from each other.
[0057]
Further, the type and number of the ink compositions constituting the color recording ink set of the present invention are not particularly limited as long as a plurality of black ink compositions according to the present invention are included as an ink set member. Examples of the ink set according to the present invention include five color ink sets of yellow, cyan, magenta, a first black ink (containing a complementary colorant), and a second black ink (containing no complementary colorant); , Cyan, magenta, a first black ink (containing a colorant for complementary colors), a second black ink (containing no colorant for complementary colors), light cyan, and light magenta in seven colors; yellow, cyan, magenta, and first Black ink (containing colorant for complementary color), second black ink (containing no colorant for complementary color), light cyan, light magenta, and black Ink set of 8 colors of yellow; ink set of 7 colors of yellow, magenta, cyan, first black ink (containing a complementary colorant), second black ink (not including a complementary colorant), light magenta, and light cyan An ink set of eight colors of yellow, cyan, magenta, a first black ink (containing a colorant for a complementary color), a second black ink (no colorant for a complementary color), red, green, and blue; yellow, cyan, and magenta , A first black ink (containing a colorant for complementary color), a second black ink (containing no colorant for complementary color), an ink set of eight colors of orange, green, and blue; and yellow, magenta, cyan, and first black ink (Comprising a colorant for complementary color), a second black ink (containing no colorant for complementary color), orange, green and violet 8 The ink set; or, an ink set comprising a further black ink composition in the ink set of the; can be mentioned.
The ink set of the present invention also includes the color ink set and the monochrome ink set including two or more types of black ink compositions containing a complementary colorant having different contents of the colorant for a complementary color.
[0058]
In the present specification, “light magenta” and “light cyan” ink compositions generally mean a magenta ink composition and a cyan ink composition, respectively, for the purpose of improving the quality of a printed image by density modulation. Is an ink composition in which the concentration of the coloring material is reduced. In addition, the “dark yellow” ink composition is a yellow ink using a color material (pigment) having lower brightness and saturation than the yellow ink composition for the purpose of improving color reproducibility for dark colors such as shadow portions. A composition. Each of the red, orange, green, blue, and violet ink compositions has an intermediate color of yellow, magenta, and cyan in order to improve the color reproduction range. The ink composition used.
[0059]
The ink set of the present invention has the same configuration as the conventionally known ink set except for the fact that the complementary colorant-containing black ink composition contains carbon black and the complementary colorant. It can be used as ink for various conventionally known recording methods. Preferred ink sets are water-based, especially ink-jet recording ink sets.
Further, the recording method of the present invention is a recording method in which droplets of an ink composition are ejected and the droplets are attached to a recording medium to perform printing, and uses the ink set of the present invention. Here, the recording method is such that an ink cartridge containing the ink set of the present invention (an ink cartridge containing each black ink composition individually) is mounted on a known ink jet recording apparatus and printed on a recording medium. By doing so, it can be suitably performed.
Here, as the inkjet recording apparatus, an electrostrictive element capable of vibrating based on an electric signal is mounted, and the ink included in the ink set according to the present invention can be ejected by the vibration of the electrostrictive element. Is preferred.
A well-known ink cartridge (housing case) for housing the ink set can be suitably used.
Further, since the recorded matter of the present invention is printed by the recording method of the present invention, it is possible to correct the coloration of carbon black, and the color tone is good.
[0060]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the scope of the present invention. In the following Examples and Comparative Examples, wt% is% by weight.
[Comparative example]
(1) Preparation of black ink composition
The components shown in Table 1 below were mixed and dispersed in a sand mill (Yaskawa Seisakusho) for 2 hours together with glass beads [diameter = 1.7 mm; 1.5 times the amount (weight) of the mixture] to give a dark black ink. Compositions A1 and B1 and thin black ink compositions A2 and B2 were obtained. A styrene-acrylic acid copolymer (molecular weight = 15000; acid value = 100) was used as the water-soluble resin. The unit in Table 1 is% by weight.
[0061]
[Table 1]

[0062]
(2) Grayscale output
The dark black ink composition A1 or the thin black ink composition A2 prepared in (1) above is filled in a black ink chamber of a dedicated cartridge of an ink jet printer (MC2000; manufactured by Seiko Epson Corporation), and a dedicated recording medium (MC photographic paper) And a gray scale pattern (gray scale) of gray from white to black was output by dividing the gray scale into 17 equal parts. The output was performed by distributing the ejection amount of each ink. The output pattern was measured using a spectrophotometer (GRETAG SPM; manufactured by GRETAG), and the coordinates of the L * a * b * color system of the color difference display method defined by CIE were obtained. The conditions at that time were as follows: light source D50, no light source filter, white standard was absolute white, and viewing angle was 2 °.
The results are shown in curve a1 (dark black ink composition A1) and curve a2 (light black ink composition A2) in FIG.
[0063]
In addition, in the curves a1 and a2 in FIG. 6, three points at which the amounts of carbon black carried per unit area are the same are shown. That is, the point s1 on the curve a1 and the point s2 on the curve a2 have the same amount of carbon black per unit area, and similarly, the point t1 on the curve a1 and the point t2 on the curve a2, and The point u1 on the curve a1 and the point u2 on the curve a2 have the same amount of carbon black carried per unit area. The distance between these points (ΔC ^* ) To equation (1):
(Equation 1)

Calculated by Note that Δa ^* Is a between each point ^* Value difference, Δ ^* Is b between each point ^* The difference between the values. The results were as follows.
distance between s1 and s2 = 8.9
distance between t1 and t2 = 5.8
distance between u1 and u2 = 0.98
[0064]
Similarly, the dark black ink composition B1 or the thin black ink composition B2 prepared in (1) above is filled in a black ink chamber of a dedicated cartridge of an ink jet printer (MC2000; manufactured by Seiko Epson Corporation), and a dedicated recording medium ( (A glossy film; manufactured by Seiko Epson Corporation), and a gray-scale pattern (gray scale) of gray from white to black was output by dividing the gray scale into 17 equal parts. The output was performed by distributing the ejection amount of each ink. The color of the output pattern was measured, and a * and b * coordinates were plotted. From the dark black ink composition B1, a gray scale locus similar to the curve a1 in FIG. 6 was obtained, and from the light black ink composition B2, a gray scale locus similar to the curve A2 in FIG. 6 was obtained.
[0065]
As is clear from FIG. 6, when the colorant for complementary color is not added, the gray scale locus obtained from each of the dark black ink composition and the light black ink composition largely deviates from the origin, and Show.
[0066]
(Examples 1 and 2)
(1) Preparation of black ink composition
The components shown in Table 2 below were mixed and dispersed in a sand mill (manufactured by Yaskawa Seisakusho) for 2 hours together with glass beads [diameter = 1.7 mm; 1.5 times (weight) of the mixture] for complementary coloration. Agent-containing black ink compositions X1 and Y1, and a complementary colorant-free black ink composition X2 and Y2 were obtained. As the water-soluble resin, a styrene-acrylic acid copolymer (molecular weight = 15,000; acid value = 100) was used. The unit in Table 2 is% by weight.
[0067]
[Table 2]

[0068]
(2) Grayscale output (Ink set X: Example 1)
An ink set X (Example 1) was formed from the black ink composition X1 containing the colorant for complementary color and the black ink composition X2 containing no colorant for the complementary color, and was formed into a dedicated cartridge for an inkjet printer (MC2000; manufactured by Seiko Epson Corporation). , And charged as follows.
(A) The black ink chamber of the ink cartridge of the ink jet printer (MC2000) was filled with the black ink composition X1 containing the colorant for complementary color.
(B) The cyan ink chamber of the ink cartridge of the ink jet printer (MC2000) was filled with a black ink composition X2 containing no complementary colorant.
The ink was discharged onto a dedicated recording medium (MC photographic paper; manufactured by Seiko Epson Corporation), and a gray gradation pattern (gray scale) from white to black was output by dividing the gradation into 18 equal parts. The output was performed by distributing the ejection amount of each ink. The output pattern was measured using a spectrophotometer (GRETAG SPM; manufactured by GRETAG), and the coordinates of the L * a * b * color system of the color difference display method specified by CIE were obtained. The conditions at that time were as follows: the light source D50, no light source filter, the white standard was absolute white, and the viewing angle was 2 °. In this embodiment, among the 18 gradations from white (gradation 17) to black (gradation 0), gradations 17 to 16 are printed with the colorant-free black ink composition X2 for complementary colors, and gradations 15 to 16 are printed. No. 0 was printed with the black ink composition X1 containing the colorant for complementary color. FIG. 7 shows the results.
[0069]
(3) Grayscale output (ink set Y: Example 2)
An ink set Y (Example 2) was constructed from the black ink composition Y1 containing the colorant for complementary color and the black ink composition Y2 containing no colorant for the complementary color, and formed into a dedicated cartridge for an inkjet printer (MC2000; manufactured by Seiko Epson Corporation). , And charged as follows.
(A) The black ink chamber of the ink cartridge of the ink jet printer (MC2000) was filled with the black ink composition Y1 containing the colorant for complementary color.
(B) The cyan ink chamber of the ink cartridge of the ink jet printer (MC2000) was filled with the colorant-free black ink composition Y2 for a complementary color.
The ink was discharged onto a dedicated recording medium (MC photographic paper; manufactured by Seiko Epson Corporation), and a gray gradation pattern (gray scale) from white to black was output by dividing the gradation into 18 equal parts. The output was performed by distributing the ejection amount of each ink. The output pattern was measured using a spectrophotometer (GRETAG SPM; manufactured by GRETAG), and the coordinates of the L * a * b * color system of the color difference display method defined by CIE were obtained. The conditions at that time were as follows: light source D50, no light source filter, white standard was absolute white, and viewing angle was 2 °. In the present embodiment, out of the 18 gradations from white (gradation 17) to black (gradation 0), gradation 17 and gradations 6 to 0 are printed with the colorant-free black ink composition Y2 for complementary colors, Tones 16 to 7 were printed with the black ink composition Y1 containing the colorant for complementary color. The results are shown in FIG.
[0070]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the ink set which can correct | amend the banding property generate | occur | produced in gray of intermediate gradation or dark gray is provided.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing a gray scale locus plotted on a * and b * coordinates of an L * a * b * color system defined by a CIE defined by CIE.
FIG. 2 is a diagram showing a unit area of the surface of a recording medium using carbon black in an amount necessary to express the same gray using a thin black ink [FIG. 2 (1)] or a dark black ink [FIG. 2 (2)]. FIG. 7 is an explanatory diagram schematically showing a state in which the ink droplet is ejected by adjusting the duty so that the ink droplet adheres to the area.
FIG. 3 shows a gray scale locus of a dark black ink and a virtual gray scale locus of a light black ink plotted at a * and b * coordinates of an L * a * b * color system of a color difference display method defined by CIE. It is explanatory drawing which shows typically that it overlaps.
FIG. 4 is an explanatory view schematically showing a gradation dividing method for a complementary colorant-containing ink composition and a complementary colorant-free ink composition in a dark black ink showing a gray scale locus of a curve d in FIG. 1; It is.
FIG. 5 is an explanatory view schematically showing a gradation division method between a complementary colorant-containing ink composition and a complementary colorant-free ink composition in a thin black ink showing a gray scale locus of a curve e in FIG. It is.
FIG. 6 is a graph showing the actual gray scale locus of dark black ink and light black ink created in the comparative example at a * and b * coordinates.
FIG. 7 is a graph showing the actual gray scale locus of the ink set X created in Example 1 at a * and b * coordinates.
FIG. 8 is a graph showing the actual gray scale locus of an ink set Y created in Example 2 on a * and b * coordinates.

Claims (15)

A first black ink composition containing carbon black and a complementary colorant, and carbon black in a concentration substantially equal to the concentration of carbon black in the first black ink composition. An ink set comprising at least one combination with a second black ink composition that does not contain the same. The first black ink composition has a general formula (1) as a complementary colorant:

The ink set according to claim 1, further comprising a pigment represented by the formula: wherein p is an integer of 0 to 3. The carbon black content in the first black ink composition is 0.01 to 10% by weight based on the total weight of the first black ink composition, and the carbon black content of the pigment represented by the general formula (1) is The ink set according to claim 2, wherein the content is 0.01 to 5% by weight based on the total weight of the first black ink composition. The first black ink composition has a general formula (2) as a complementary colorant:

The ink set according to claim 1, further comprising a pigment represented by the following formula: The carbon black content in the first black ink composition is 0.01 to 10% by weight based on the total weight of the first black ink composition, and the carbon black content of the pigment represented by the general formula (2) is The ink set according to claim 4, wherein the content is 0.01 to 5% by weight based on the total weight of the first black ink composition. The first black ink composition has a general formula (1) as a complementary colorant:

(Where p is an integer of 0 to 3), and a first combination containing a pigment represented by the general formula (2) as a complementary colorant:

2. The ink set according to claim 1, comprising a pigment represented by the formula: and a second combination having a carbon black concentration higher than the carbon black concentration in the first combination. In the first combination, the carbon black content in the first black ink composition containing the pigment represented by the general formula (1) is set to be 0.1 to the total weight of the first black ink composition. 0.1 to 10% by weight, and the content of the pigment represented by the general formula (1) is 0.01 to 5% by weight based on the total weight of the first black ink composition. In the second combination, the carbon black content in the first black ink composition containing the pigment represented by the general formula (2) is 0.01 to 0.01% based on the total weight of the first black ink composition. 7. The pigment according to claim 6, wherein the content of the pigment represented by the general formula (2) is 0.01 to 5% by weight based on the total weight of the first black ink composition. The described ink set. The ink set according to any one of claims 1 to 7, wherein the ink set is aqueous. 9. The black ink composition according to claim 1, wherein the at least one black ink composition contains at least one surfactant selected from the group consisting of an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. An ink set according to any one of the preceding claims. 10. The ink set according to claim 9, wherein the nonionic surfactant is an acetylene glycol-based surfactant. The ink set according to any one of claims 1 to 10, wherein the at least one black ink composition further contains a water-soluble organic solvent. The ink set according to any one of claims 1 to 10, which is used for inkjet recording. A recording method for performing printing by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink set according to any one of claims 1 to 11 is used. Recording method. A recorded matter printed by the recording method according to claim 12. An electrostrictive element capable of vibrating based on an electric signal is mounted, and the ink set according to any one of claims 1 to 11 can be ejected by the vibration of the electrostrictive element. An ink jet recording apparatus characterized in that:

Images