JP3931639B2 - Aqueous ink composition for use in an ink jet printer - Google Patents

Description

ここで、ｍは多分散ポリスチレンブロックに対する平均値で、１０ないし２０の範囲にある；ｐは多分散（メタ）アクリレートに対する平均値で、２０ないし４０の範囲にある；そしてＺは水素（Ｈ）かメチル基（ＣＨ₃）である。上の２ブロック共重合体は、公知の方法によって調製するか市販品を購入することができる。次の文献：Ｚｈｏｎｇ，Ｘ．Ｆ．，Ｖａｒｓｈｎｅｙ，Ｓ．Ｎ．およびＥｉｓｅｎｂｅｒｇ，Ａ．，Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ，１９９２， ２５，７１６０〜７１６７およびＣａｏ，Ｔ．，Ｍｕｎｋ，Ｐ．，Ｒａｍｉｒｅｄｄｙ，Ｃ．，Ｔｕｚａｒ，Ｚ．，Ｗｅｂｂｅｒ，Ｓ．Ｅ．，Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ，１９９１，２４，６３００〜６３１０にはその方法が記載されている。このタイプの２ブロック共重合体はＰｏｌｙｍｅｒ Ｓｏｕｒｃｅ Ｉｎｃ．（カナダ、ケベック州、ドーバル）から購入することができる。上記化合物の化学構造から分かるように、この化合物はｐＨ値が８より高い水性溶液中でポリ（メタ）アクリレートのカルボキシル基が多重解離するためポリアニオンとして存在する。
【００３１】
本発明のミセル形成成分に対する条件を満たす化合物の別のタイプの一般構造式を次に示す：
【００３２】
【化２】

ここで、ｘは多分散オリゴ糖に対する平均値で、１ないし１４の範囲にある；ｎは２ないし１２の範囲にある；Ｒはアリール、置換アリール、アルキルアリール、置換アルキルアリール、ピリジルまたは炭素原子数が５ないし２０の置換ピリジル基である。上記化学構造から明らかなように、この化合物はｐＨ値が８より高い水性溶液中でオリゴ糖成分のカルボキシル基が多重解離するためポリアニオンとして存在する。
【００３３】
上記化合物のオリゴ糖部分は、アルギン酸およびペクチンといった天然多糖類から化学的な方法または酵素法を使って容易に得ることができる。上記化合物を得るには２つの還元的アミノ化反応を使用するのが最も簡単である。第１の還元アミノ化反応は、オリゴ糖前駆体および次の一般式で表される過剰量の分枝ポリアミン化合物とを使用して行われる。
【００３４】
【化３】

ここで、ｎは２ないし１２の範囲にある。ｎが４の分枝ポリアミンは、ＤＳＭＮｅｗ Ｂｕｓｉｎｅｓｓ Ｄｅｖｅｌｏｐｍｅｎｔ（オランダ）から「Ａｓｔｒａｍｏｌ Ａｍ４」の名称で市販されている。過剰の分枝アミンを除去したのち、第１の還元アミノ化で得られた生成物と、一般式Ｒ−ＣＨＯ（ここでＲはアリール、置換アリール、アルキルアリール、置換アルキルアリール、ピリジルまたは炭素原子数が５ないし２０の置換ピリジル基である）で表される過剰量のアルデヒドとを使用して第２の還元的アミノ化反応を行う。このタイプのミセル形成成分を調製するために使用が可能な好ましいアルデヒドの例を以下に列挙するが、このリストが包括的なものでないことは言うまでもない。好ましいアルデヒド：ピペオナール、２，３−（メチレンジオキシ）ベンズアルデヒド、１−ナフタルデヒド、２−ナフタルデヒド、４−メトキシ−１−ナフタルデヒド、４−ビフェニルカルボキシアルデヒド、３−フェノキシベンズアルデヒド、４−フェノキシベンズアルデヒド、２−フルオレンカルボキシアルデヒド、３−ベンジルオキシベンズアルデヒド、４−ベンジルオキシベンズアルデヒド、３−（４−メトキシフェノキシ）ベンズアルデヒド、９−アントラルデヒド、２−ベンジルオキシ−３−メトキシベンズアルデヒド、３−ベンジルオキシ−４−メトキシベンズアルデヒドおよび４−ベンジルオキシ−３−メトキシベンズアルデヒド。
【００３５】
本発明のインク組成物中の建染染料の量は０．１ないし４０重量％ミセル形成成分が好ましい。
【００３６】
水
水は本発明の水性インク組成物の主要な溶媒である。水としては通常脱イオン水が使用される。本発明で言う「水性担持媒体」とは、水、水と混和する共溶媒、水溶性界面活性剤、および水溶性添加剤の混合物を意味する。本発明のインク組成物中における水性担持媒体の好ましい量は、５０ないし９９．８重量％である。
【００３７】
水と混和する共溶媒
本発明のインク組成物は、当業者によって最も良いとされるインク配合の処方に従って１つまたは複数の水と混和する共溶媒を含むことができる。水と混和しうる有機共溶媒はよく知られており、その例を挙げれば次の通りである：（１）イソプロピルアルコール、ブチルアルコールなどのアルコール類、（２）アセトン、メチルエチルケトンなどのケトン類、（３）テトラヒドロフラン、ジオキサンなどのエーテル類、（４）酢酸エチル、プロピレンカーボネートなどのエステル類、（５）エチレングリコール、グリセロール、グリセロールエトキシレート、プロピレングリコール、ブチレングリコール、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、１，２−ペンタンジオール、１，２−ヘキサンジオール、ポリエチレングリコール、ポリプロピレングリコール、１，２，６−ヘキサトリオール、チオグリコールなどの多価アルコール類、（６）ジエチレングリコール−モノ−ｎ−ブチルエーテル、トリエチレングリコール−モノ−ｎ−ブチルエーテル、ジエチレングリコール−モノ−ｎ−ヘキシルエーテル、ジプロピレングリコールモノメチルエ−テル等の多価アルコールのアルキルエーテル類、（７）尿素、ピロリドン、Ｎ−メチル−２−ピロリドンなどの含窒素化合物および（８）ジメチルスルホキシド、テトラメチレンスルホキシドなどの含硫黄化合物。上のリストは包括的なものでないことは言うまでもないし、本発明のインク配合を制限するものでもない。言い換えれば、他の共溶媒も使用可能であり、かつ本発明の範囲内に入る。
【００３８】
水溶性界面活性剤
本発明のインク組成物は、当業者によって最も良いとされるインク配合の処方に従って１つまたは複数の水溶性界面活性剤を含むことができる。一般に、ノニオン界面活性剤が、発泡しない点で好ましい。有用な界面活性剤の例を挙げれば次の通りである：アセチレン系ジオールエチレンオキサイド付加体、高級アルコールエチレンオキサイド付加体、アルキルフェノールエチレンオキサイド付加体、高級アルキルアミンエチレンオキサイド付加体、エチレンオキサイドプロピレンオキサイド共重合体およびポリエーテル変性ジメチルポリシロキサン。上のリストは包括的なものでないことは言うまでもないし、本発明のインク配合を制限するものでもない。言い換えれば、他の界面活性剤も使用可能であり、かつ本発明の範囲内に入る。
【００３９】
その他の成分
ｐＨ値が８より高いインク組成物を得るために、インクには、上に記載した成分の他に、さらに随意に１つまたは複数の塩基を加えることができる。好ましい塩基には無機塩基、有機塩基およびそれらの混合物が含まれる。好適な塩基の例は次の通りである：水酸化リチウム、水酸化ナトリウム、水酸化カリウム、水酸化ルビジウム、水酸化セシウム、アンモニア、メチルアミン、ジメチルアミン、トリメチルアミン、モルホリン、Ｎ−メチルモルホリン、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、トリイソプロパノールアミン、Ｎ−メチルモノエタノールアミン、Ｎ，Ｎ−ジメチルモノエタノールアミン、Ｎ−メチルジエタノールアミンおよび水酸化テトラメチルアンモニウム。塩基添加物の他に、インクには、さらに随意にｐＨ緩衝剤、殺菌剤、腐食防止剤、粘度調整剤、紫外線吸収剤および抗酸化剤を添加することができる。インクに使用されるその他の成分の総量に特別な制限はない。インクの全成分の量は、インクの表面張力が約２０ないし４０ｄｙｎｅ／ｃｍの範囲に、そしてインクの粘度は約１．０ないし１０．０ｍＰａ・ｓの範囲にそれぞれ収まるように選択される。
【００４０】
インクの調製
本発明のインク組成物は、理論的にはいかなる公知の方法によっても調製することができる。しかし、上で指摘したように建染染料の還元された可溶性ロイコ塩／塩基型を使用する方法は、本発明者の手中に安定な分散液を与えなかった。本発明の安定な建染染料分散液を調製するために使用できる方法は、建染染料の標準的な酸化型の使用を共通の要素としている。具体的には、ジメチルスルホキシド、スルホラン、Ｎ−メチル−２−ピロリドン、ジメチルホルムアミド、ジメチルアセトアミドおよびヘキサメチルホスホラミドなどの、極性の強い有機溶媒中の標準的な酸化型建染染料の溶液が使用される。
【００４１】
有用な１つの方法においては、最初に、少なくとも１つの建染染料と少なくとも１つのミセル形成成分とを、極性の強い有機溶媒に部分的に、または完全に溶かす。ミセル形成成分は、遊離酸／非解離型の形で溶解させる。一般にこれらのミセル形成成分は、この条件下では極性の強い有機溶媒に完全に溶解する。出発物質の建染染料が極性の強い有機溶媒中に溶ける度合いは、建染染料の種類と、ミセル形成成分の共溶媒和能とに依存する。攪拌、ミリング、加熱、超音波処理またはこれらの方法の組み合わせによって均一にしたのち、適当な溶媒を加えると建染染料とミセル形成成分の両方を含む固体が沈殿する。本発明における有用な沈殿溶媒としてはアルコールとケトンとがあり、具体的に何を選ぶかは、建染染料とミセル形成成分の種類に依存する。この固体を沈殿させたのち、それを攪拌、ミリング、加熱、超音波処理またはこれらの方法の組み合わせによって水性塩基溶液中に分散させる。水性溶液中の塩基の量は、ミセル形成成分の遊離酸／非解離型を中和し、かつ分散液のｐＨ値が８より高く１０以下とするのに十分な量とする。水性塩基溶液を調製するための好ましい塩基として、無機塩基、有機塩基およびそれらの混合物を挙げることができる。その例は、上記「その他の成分」の項に列挙されている。
【００４２】
上記の方法と多くに点で似ている別の有用な方法においては、最初に、少なくとも１つの建染染料と少なくとも１つのミセル形成成分とを、極性の強い有機溶媒に溶かす。上記のように、ミセル形成成分は、遊離酸／非解離型の形で溶解させる。攪拌、ミリング、加熱、超音波またはこれらの方法の組み合わせによって均一にする。均一になったら、その均一溶液に非水塩基溶液をゆっくり加える。ミセル形成成分、非水塩基溶液中の塩基、極性の強い有機溶媒の種類によっては、この添加によって建染染料とミセル形成成分の両方を含む固体の沈殿を生成させることができる。非水溶液の量は、ミセル形成成分の遊離酸／非解離型を中和するのに十分な量とする。固体が沈殿した場合はそれを分離し、攪拌、ミリング、加熱、超音波処理またはこれらの方法の組み合わせによって水性塩基溶液中に分散させる。固体が沈殿しなかった場合は、適当な溶媒を加えて沈殿させる必要がある。上記のように、本発明の有用な沈殿溶媒は、アルコール類とケトン類である。この固体を沈殿させた後は、攪拌、ミリング、加熱、超音波処理またはこれらの方法の組み合わせによって水性塩基溶液中に分散させる。
【００４３】
上記の２つの方法のいずれかによって得られた建染染料分散液は、インクジェットプリンタで使用するためのインクの配合に使用する前に、公知の方法によって濃縮および／または精製してもよい。濃縮および精製に有用な方法は限外濾過法である。限外濾過メンブランの孔径を慎重に選択することによって、過剰のミセル形成成分および過剰の塩基を含む可溶不純物を強制的に限外濾過膜を通過させて流出液だめに集める。一般的には、分散されない不溶成分を除くために分散液またはインク配合物を濾過するのが望ましい。金属メッシュフィルタとメンブランフィルタの両方が使用可能である。濾過を行うには分散液を加圧してもよいし、濾過装置の受器末端を減圧にしてもよい。インクジェットプリンタのプリンタヘッドに設置されたノズルの詰まりの原因になる大きな粒子を除去するために遠心分離を行うこともできる。精製、濃縮した建染染料分散液が得られたら、有効と思われる順序に従って所望成分を混合してインクを配合する。インクの配合が終わったら、その配合によっては再度濾過を行う。
【００４４】
理論に束縛される意図はないが、いくつかの理由によって、本発明の方法に従えば安定な建染染料分散液が得られるものと信じられる。第１の理由は、本発明の特許請求項に従って指定されたミセル形成成分が、特別なタイプの分散手段として使用されることである。水性溶液中で平均粒径が２０ｎｍより大きなミセルを形成しなければならないという基準を満たすミセル形成成分は、あらゆる実用目的に対して、２つの異なるブロックから成る高分子に限定される。異なるブロックの１つは、水性溶液中の高分子電解質であり、もう一方のブロックは比較的分子量の大きな疎水性の化合物である。水性溶液中に溶かした時にこれらの高分子はそれ自身で集合して一様な球状ミセルを形成し、そのミセルの中では不溶な疎水性ブロックがミセルのコアに隔離され、可溶性の高分子電解質ブロックは、ミセルを溶液状態に分散させておく殻を形成する。特殊なこれらのミセルタイプは、よく知られた洗浄剤ミセルと表面的には似ているが、ミセルの大きさはそれよりはるかに大きく、安定性もかなり大きい。標準的な酸化型の建染染料は、水に溶解しない疎水性の物質であるため、類似の疎水性物質に強い親和性を示す。ここでも、理論に束縛される意図はないが、疎水性の建染染料が、本発明のミセルの大きな疎水性コアに対して強い親和性を持つことが、これら建染染料分散液の安定性に大きく貢献するという利点をもたらすものと思われる。
【００４５】
安定な建染染料分散液が得られる第２の理由は、疎水性の建染染料が、疎水性の存在種としてミセルの疎水性コア内に包含されていることにあるものと思われる。本発明の方法によれば、少なくとも１つの疎水性建染染料と少なくとも１つのミセル形成成分とが極性の強い溶媒に溶解される。本発明のミセル形成高分子の２つのブロックは、極性の強い有機溶媒中でさえ弱い高分子の自己会合が起こりうるほど、大きな違いが持たせてある。有機溶媒の極性が大きいため、高分子の自己会合は、水性溶液中の自己会合と同じタイプ、すなわち、疎水性のコアと親水性部分の強く溶媒和した殻から成ることが想定される。標準的な酸化型のほとんどの建染染料は、本発明のミセル形成成分が存在しても非水性極性有機溶媒にそれほど溶けないが、均一な溶液が得られる。ここでも、理論に束縛される意図はないが、疎水性の建染染料が、ミセルの疎水性コアに対して強い親和性を持つことが、極性の強い有機溶媒にこれら建染染料分散液の溶解性に大きく貢献するというかなりの利点をもたらすものと思われる。
【００４６】
安定な建染染料分散液が得られる第３の理由は、疎水性の建染染料を疎水性のコア内に包含して含む会合前のミセルは、極性の強い有機媒体から水性溶液に移行する時に保存されることにあるものと思われる。上記の第１の方法では、均一な溶液が得られた後で沈殿溶媒が加えられる。この目的に使用される溶媒のタイプであるアルコールとケトンは、ミセルのコアを壊すものとは想定されない。上記の第２の方法では、均一な溶液が得られた後で非水性塩基溶液が加えられる。この添加によってミセルの遊離酸／非解離部分が高分子電解質型に変換され、変化を受けていないミセルの沈殿をもたらす。このタイプの沈殿がミセルのコアを壊すとは想定されない。ここでもやはり理論に束縛される意図はないが、疎水性コアに疎水性建染染料を含んでいる変化を受けていないミセルが、有機溶媒から水性溶液に移動することが、安定な建染染料分散液の調製に大きく貢献するという利点をもたらすものと思われる。
【００４７】
【実施例】
本発明は以下の具体的な実施例により、一層明確になる。作業はすべて十分換気したドラフタ内で実施した。
【００４８】
ミセル形成成分
下記の一般式で表されるミセル形成成分を以下のようにして調製した：
【００４９】
【化４】

式中、多分散オリゴ糖部分の平均値ｘは５；ｎは４；Ｒは１−ナフチルである。
【００５０】
アルギン酸（超低粘度アルギン酸；紀文フードケミファ、日本）１５０ｇを２０００ｍＬビーカーに入れた脱イオン水５００ｍＬに加えてスラリー状にした。攪拌機で上から機械的に攪拌しながら、このスラリーに水酸化リチウム１水和物２８．２ｇを加えた。さらに脱イオン水を加えて溶液の総体積を６００ｍＬとした。３４．５重量％の過酸化水素水１００ｇを加え、生成した溶液を４時間攪拌し、それから１６時間放置した。次に、消泡剤としてｎ−ノナノール１ｍＬと新しく調製した０．６５ｇの硫酸第一鉄７水和物を含む溶液４０ｍＬとをアルギン酸／過酸化水素水溶液に攪拌しながら加えた。溶液を４時間激しく攪拌した。この間に著しい発熱が起こり、その後収まった。３４．５重量％の過酸化水素水４５ｇを添加し、生成した溶液を短時間攪拌し、つづいてそれを１６時間放置した。次に、穏やかな発熱が起こり、それが収まって溶液の色が暗色に変化するまで混合物を５０゜Ｃに加熱した。暗色に変化した溶液を室温まで放冷し、ワットマンの濾紙Ｎｏ．１を使って濾過した。濾液を１Ｌナスフラスコに移し、再循環アスピレータに接続した回転式蒸発器で液量が３００ｍＬになるまで濃縮した。回転式蒸発器の水浴温度は約５５゜Ｃに維持した。暗色の濃縮溶液を１Ｌビーカーに移し水で洗い込んで、全液量を３５０ｍＬとした。この溶液を激しく攪拌しながら氷酢酸３５０ｍＬを加ると、ふわふわした沈殿が生成した。混合物に３０分間超音波処理を行い、それから１６時間放置した。混合物を卓上遠心分離器にかけて固体を分離した。固体の一部を１００ｍＬ遠沈管４本に移し、３５００ｒｐｍで１時間遠心分離した。上澄液を捨てたのち、遠心分離にかけていない残り分を先の遠沈管４本に移し、一杯になった遠沈管を３５００ｒｐｍで１時間遠心分離した。１００ｍＬの水で洗い込んで全固体を１Ｌポリプロピレン容器に移した。ポリプロピレン容器に封をして６０゜Ｃの定温乾燥機に１６時間置いた。次に、激しく攪拌しながら全量が１Ｌになるまでゆっくり無水エタノールを加えた。混合物をワットマンの濾紙Ｎｏ．１で濾過した。湿った固体を９５％エタノールで洗浄し、空気中に放置して乾燥させた。最後に一定重量になるまで固体を減圧乾燥した。生成物の収量は２０ｇであった。手順を６回くり返して全部で約１２０ｇの生成物を合成した。オリゴ糖の平均重合度は、Ｐ．Ａ．ＳｈａｆｆｅｒとＭ．Ｓｏｍｏｇｙｉの方法（Ｊ．Ｂｉｏｌ．Ｃｈｅｍ．１９３３，１００，６９５〜７１３）によって決定した。エタノールと水から再結晶したガラクツロン酸１水和物をこの方法に対する単糖の比較基準物質として使用した。オリゴ糖試料の平均重合度は、７であった。上の式で平均重合度に相当するｘの値は５となる。
【００５１】
上に記載したオリゴ糖のポリアニオン性は、Ｐ．Ｊ．Ｓｉｍｍｓ，Ａ．Ｔ．Ｈｏｔｃｈｋｉｓｓ，Ｊｒ．，Ｐ．Ｌ．ＩｒｗｉｎおよびＫ．Ｂ．Ｈｉｃｋｓ，Ｃａｒｂｏｈｙｄｒａｔｅ Ｒｅｓｅａｒｃｈ，１９９５，２７８，１〜９に記載されている方法に従い、高速液体クロマトグラフィ（ＨＰＬＣ）を使って確認した。ヒューレット・パッカード製１１００シリーズ高速液体クロマトグラフ装置を使用し、アセトニトリル−リン酸ナトリウム緩衝液（ｐＨ５）５０：５０を移動相として、試料をＣｙｃｌｏｂｏｎｄ Ｉカラム（東京化成、２５０ｍｍ×４．６ｍｍ）から溶出させた。重合度３ないし１０に相当するオリゴ糖のピークが観察され、ｐＨ５でオリゴ糖成分がポリアニオンとして挙動することが確認された。物理化学的な原理から、この挙動はｐＨ値が８より高い水性溶液中でも変わらないものと推定される。同様に、詳細は後で述べる方法によってこのオリゴ糖から調製したミセル形成成分も、ｐＨ値が８より高い水性溶液中でポリアニオンとして挙動することが推定される。
【００５２】
上で調製したオリゴ糖１２０ｇと分枝ポリアミン「Ａｓｔｒａｍｏｌ Ａｍ４」（ＤＳＭ Ｎｅｗ Ｂｕｓｉｎｅｓｓ Ｄｅｖｅｌｏｐｍｅｎｔ、オランダ）７５ｇを、５Ｌのビーカーに入れた脱イオン水５００ｍＬに溶解した。ビーカーにふたをしないまま、換気能の高いドラフト内に５日間放置した。攪拌機で上から激しく攪拌しながら、この粘稠な溶液に水素化ホウ素ナトリウム３３ｇを加えた。８時間攪拌を続けたのち、溶液を１６時間放置した。次に、激しく攪拌しながら全体積が５Ｌになるまでメタノールをゆっくり添加した。このメタノールの添加によってふわっとしたイエローの固体が沈殿した。混合物を１６時間放置すると固体はかなり沈積した。上澄液を傾斜法によって除いた。混合物を激しく攪拌しながら全体積が５Ｌになるまでメタノールを添加した。混合物を再度１６時間放置して固体を沈積させた。傾斜法によって上澄液を除き、固体スラリーに残るメタノール量ができるだけ少なくなるようにした。
【００５３】
攪拌しながら上で調製したスラリーにジメチルスルホキシド１．５Ｌと１−ナフトアルデヒド７０ｇを添加した。スラリーを５５゜Ｃに加熱し、６時間攪拌し、それから１６時間放置した。次に、混合物を激しく攪拌しながら、９５％シアノ水素化ホウ素ナトリウム２５ｇと塩化テトラエチルアンモニウム７０ｇとからメタノール中で複分解して調製したシアノ水素化ホウ素テトラエチルアンモニウムのメタノール溶液２００ｍＬを添加した。混合物を８時間攪拌し、それから１６時間放置した。次に、１−ナフタルアルデヒド１００ｇと、９５％シアノ水素化ホウ素ナトリウム４０ｇと塩化テトラエチルアンモニウム１０５ｇとからメタノール中で複分解して調製したシアノ水素化ホウ素テトラエチルアンモニウムのメタノール溶液３５０ｍＬを加えた。混合物を激しく攪拌しながらすべての固体がちょうど溶けきるまでトリフルオロ酢酸を滴下した。滴下したトリフルオロ酢酸の重さはおよそ１４０ｇであった。褐色を帯びたイエローの溶液を８時間攪拌し、それから１６時間放置した。溶液を５５゜Ｃに加熱しながら溶液をさらに１０時間攪拌し、それから１６時間放置した。溶液を激しく攪拌しながら、混合物の全体積が５Ｌになるまで９５％エタノールを加えた。アルコールを添加していくにつれてふわふわした黄白色の沈殿が生成した。ビーカーに覆いをして４０時間放置した。大半の上澄液を傾斜法で除き、残った混合物を１００ｍＬの遠沈管に入れ、３０００ｒｐｍで３０分間遠心分離にかけて固体を分離した。分離した湿った固体を沸騰メタノール中に３０分間懸濁させた。混合物を室温まで冷却し、目の細かい（孔径１６〜４０ミクロン）ガラス濾過器で生成物を吸引濾過した。固体をメタノールで数回洗浄し、それから空気中で乾燥させた。最後に、固体を一定の重さになるまで減圧乾燥した。生成物の収量は２１０ｇであった。
【００５４】
乾燥固体３００ｍｇを脱イオン水５ｍＬに入れ、５％水酸化リチウムを滴下して溶解した。標準ｐＨ試験紙で調べた溶液のｐＨは１０であった。５分間超音波を照射して均一にし、それからＰｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計でミセル形成成分の粒径を測定した。測定された粒子径は７８ｎｍであった。
【００５５】
分散液の調整
イエロー分散液
ミセル形成成分（上で調製）３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｙｅｌｌｏｗ ５Ｇ（オーストラリア、ＮＳＷ ２０３１、Ｒａｎｄｗｉｃｋ、Ｂａｔｉｋ Ｏｅｔｅｒｏから入手）１６ｇおよびジメチルスルホキシド４００ｍＬを３Ｌビーカー中で混合し、混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理によって均一な溶液が得られた。混合物を上から激しく攪拌しながら、イソプロピルアルコールを加えて全体積を２．５Ｌにした。イソプロピルアルコールの添加によってイエローの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体を水酸化リチウム１水和物５ｇを含む脱イオン水３００ｇに加えた。混合物を磁気攪拌器で２時間攪拌して均一分散液を得た。分散液に１５分間超音波処理を行ったのち、５ミクロンのメンブランフィルタを通して濾過し、少量の不溶物を除去した。ｐＨ計で測定したこの時点での分散液のｐＨは１１．５であった。１０，０００ＮＭＷＬ低結合再生セルロース濾過板（１０枚）を備えた実験室用Ｍｉｌｌｉｐｏｒｅ Ｍｉｎｉｔａｎを使って限外濾過し、過剰の水酸化リチウム、イソプロピルアルコールおよびジメチルスルホキシドを分散液から除去した。分散液に脱イオン水（１５００ｍＬ）を数回に分けて加えて廃棄溶液の損失を補填した。最後の脱イオン水を加えたのち分散液の体積が約８０ｍＬになるまで濃縮した。次に、脱イオン水を滴下して分散液の重量を１２８ｇに調整した。生成したイエロー分散液のｐＨは９．５であった。Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で測定した粒子径は１０１ｎｍであった。
【００５６】
レッド分散液
ミセル形成成分（上で調製）３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｒｅｄ ３Ｂ（オーストラリア、ＮＳＷ ２０３１、Ｒａｎｄｗｉｃｋ、Ｂａｔｉｋ Ｏｅｔｅｒｏから入手）１５ｇおよびＮ−メチル−２−ピロリドン５００ｍＬを３Ｌビーカー中で混合した。混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理によって均一な溶液が得られた。混合物を上から激しく攪拌しながら、９５％エタノールを加えて全体積を３Ｌにした。９５％エタノールの添加によってレッドの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体を水酸化リチウム１水和物５ｇを含む脱イオン水３００ｇに加えた。混合物を磁気攪拌器で２時間攪拌して均一分散液を得た。分散液に１５分間超音波処理を行ったのち、５ミクロンのメンブランフィルタを通して濾過し、少量の不溶物を除去した。ｐＨ計で測定したこの時点での分散液のｐＨは１１．７であった。１０，０００ＮＭＷＬ低結合再生セルロース濾過板（１０枚）を備えた実験室用Ｍｉｌｌｉｐｏｒｅ Ｍｉｎｉｔａｎを使って限外濾過し、過剰の水酸化リチウム、エタノールおよびＮ−メチル−２−ピロリドンを分散液から除去した。分散液に脱イオン水（１５００ｍＬ）を数回に分けて加えて廃棄溶液の損失を補填した。最後の脱イオン水を加えたのち分散液の体積が約７５ｍＬになるまで濃縮した。次に、脱イオン水を滴下して分散液の重量を１２５ｇに調整した。生成したレッド分散液のｐＨは９．５であった。Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で測定した粒子径は９８ｎｍであった。
【００５７】
ブルー分散液
ミセル形成成分（上で調製）３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｂｌｕｅ ＢＣ（オーストラリア、ＮＳＷ ２０３１、Ｒａｎｄｗｉｃｋ、Ｂａｔｉｋ Ｏｅｔｅｒｏから入手）１２ｇおよびＮ−メチル−２−ピロリドン５００ｍＬを３Ｌビーカー中で混合した。混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理によって均一な溶液が得られた。混合物を上から激しく攪拌しながら、水酸化テトラメチルアンモニウム５水和物２５ｇをエタノール１Ｌに溶かした溶液を加えた。塩基溶液の添加によってブルーの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体をトリフルオロメタンスルホン酸リチウム２０ｇを含む脱イオン水３００ｇに加えた。混合物を磁気攪拌器で２時間攪拌して均一分散液を得た。分散液に１５分間超音波処理を行ったのち、５ミクロンのメンブランフィルタを通して濾過し、少量の不溶物を除去した。ｐＨ計で測定したこの時点での分散液のｐＨは１１．６であった。１０，０００ＮＭＷＬ低結合再生セルロース濾過板（１０枚）を備えた実験室用Ｍｉｌｌｉｐｏｒｅ Ｍｉｎｉｔａｎを使って過剰のリチウム塩、テトラメチルアンモニウム塩、エタノールおよびＮ−メチル−２−ピロリドンを分散液から除去した。分散液に脱イオン水（１５００ｍＬ）を加えて廃棄溶液の損失を補填した。最後の脱イオン水を加えたのち分散液の体積が約７０ｍＬになるまで濃縮した。次に、脱イオン水を滴下して分散液の重量を１２０ｇに調整した。生成したブルー分散液のｐＨは９．５であった。Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で測定した粒子径は９１ｎｍであった。
【００５８】
ブラック分散液
ミセル形成成分（上で調製）３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｂｌａｃｋ ＡＣ（オーストラリア、ＮＳＷ ２０３１、Ｒａｎｄｗｉｃｋ、Ｂａｔｉｋ Ｏｅｔｅｒｏから入手）２０ｇおよびジメチルスルホキシド５００ｍＬを３Ｌビーカー中で混合した。混合物を６０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理によって均一な溶液が得られた。混合物を上から激しく攪拌しながら、水酸化テトラメチルアンモニウム５水和物２５ｇをエタノール１Ｌに溶かした溶液を加えた。塩基溶液の添加によってブラックの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体をトリフルオロメタンスルホン酸リチウム２０ｇを含む脱イオン水３００ｇに加えた。混合物を磁気攪拌器で２時間攪拌して均一分散液を得た。分散液に１５分間超音波処理を行ったのち、５ミクロンのメンブランフィルタを通して濾過し、少量の不溶物を除去した。ｐＨ計で測定したこの時点での分散液のｐＨは１１．５であった。１０，０００ＮＭＷＬ低結合再生セルロース濾過板（１０枚）を備えた実験室用Ｍｉｌｌｉｐｏｒｅ Ｍｉｎｉｔａｎを使って過剰のリチウム塩、テトラメチルアンモニウム塩、エタノールおよびジメチルスルホキシドを分散液から除去した。分散液に脱イオン水（１５００ｍＬ）を加えて廃棄溶液の損失を補填した。最後の脱イオン水を加えたのち分散液の体積が約９０ｍＬになるまで濃縮した。次に、脱イオン水を滴下して分散液の重量を１３５ｇに調整した。生成したブラック分散液のｐＨは９．５であった。Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で測定した粒子径は１０６ｎｍであった。
【００５９】
一般的なインクの調製
攪拌しながら、下記の表１に記載された成分を記載の順にビーカーに加えた。合わせた混合物を３時間撹拌した。次に、混合物を５ミクロンのメンブランフィルタを通して濾過し、インクジェットプリンタに適するインクを得た。表１では次のような略号が使用されている：水＝Ｗ；グリセロール＝ＧＬＹ；２−ピロリドン＝２Ｐ；トリエチレングリコール＝ＴＥＧ；トリエチレングリコールモノ−ｎ−ブチルエーテル＝ＴＥＧ−ｍＢＥ；Ｓｕｒｆｙｎｏｌ ４６５（Ａｉｒ Ｐｒｏｄｕｃｔｓ Ｉｎｃの製品名）＝Ｓ４６５。密度を１．０８ｇ／ｍＬとした時の４種類のインクの粘度測定値はいずれも４．２ｍＰａ・ｓであった。
【００６０】
【表１】

【００６１】
表中、（）内の数値は添加量（ｇ）を示す。
【００６２】
比較例
比較例 分散液Ａ
上記イエロー分散液の調製に使用したミセル形成成分の代わりにＪｏｎｃｒｙｌ６８２（Ｊｏｈｎｓｏｎ Ｐｏｌｙｍｅｒｓ Ｉｎｃ．の製品名）３０ｇを使用した点を除き、上記イエロー分散液の調製手順と同じ手順を試みた。この比較例を試みる前に、Ｊｏｎｃｒｙｌ ６８２ ｌ３００ｍｇを脱イオン水５ｍＬに、５％水酸化リチウム溶液を滴下して溶解した。得られた溶液のｐＨを標準ｐＨ試験紙で調べた結果は１０であった。溶液に５分間超音波処理を行って均一にしたのち、Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で粒子径の測定を試みた。しかし試料の測定はできなかったので、ミセルが形成されたという証拠は得られなかった。
Ｊｏｎｃｒｙｌ ６８２ ３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｙｅｌｌｏｗ ５Ｇ１６ｇおよびジメチルスルホキシド４００ｍＬを３Ｌビーカー中で混合した。混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理を行っても均一な溶液は得られなかった。混合物を上から激しく攪拌しながら、イソプロピルアルコールを加えて全体積を２．５Ｌにした。イソプロピルアルコールの添加によって不均一なイエローの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体を水酸化リチウム１水和物５ｇを含む脱イオン水３００ｇに加えた。大きなイエローの結晶を含む混合物が得られ、それは４時間攪拌しても均一にはならなかった。超音波処理を行っても効果は認められなかった。１０ミクロンのステンレス製メッシュを通して濾過すると、イエローの結晶とほとんど無色の濾液とに分離された。均一な分散液が得られなかったので、この試料をそれ以上評価することはできなかった。
【００６３】
比較例 分散液Ｂ
上記レッド分散液の調製に使用したミセル形成成分の代わりにデモール ＡＳの遊離酸（花王の製品名）３０ｇを使用した点を除き、上記レッド分散液の調製手順と同じ手順を試みた。デモール ＡＳ ５０ｇを脱イオン水５００ｇに溶解し、強酸性イオン交換樹脂Ｄｏｗｅｘ ５０ＷＸ２−２００ ３００ｇを充填したイオン交換樹脂カラムに流した。溶出液を回転式蒸発器で濃縮して水を除き、固体を減圧乾燥した。この比較実験を行う前に、乾燥した固体３００ｍｇを脱イオン水５ｍＬに、５％水酸化リチウム溶液を滴下して溶解した。得られた溶液のｐＨを標準ｐＨ試験紙で調べた結果は１０であった。溶液に５分間超音波処理を行って均一にしたのち、Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で粒子径の測定を試みた。しかし試料の測定はできなかったので、ミセルが形成されたという証拠は得られなかった。デモール ＡＳの遊離酸３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｒｅｄ ３Ｂ １５ｇおよびＮ−メチル−２−ピロリドン５００ｍＬを３Ｌビーカー中で混合した。混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理を行っても均一な溶液は得られなかった。混合物を上から激しく攪拌しながら、９５％エタノールを加えて全体積を３Ｌにした。９５％エタノールの添加によって不均一なレッドの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体を水酸化リチウム１水和物５ｇを含む脱イオン水３００ｇに加えた。大きなレッドの結晶を含む混合物が得られ、それは４時間攪拌しても均一にはならなかった。超音波処理を行っても効果は認められなかった。１０ミクロンのステンレス製メッシュを通して濾過すると、レッドの結晶とほとんど無色の濾液とに分離された。均一な分散液が得られなかったので、この試料をそれ以上評価することはできなかった。
【００６４】
比較例 分散液Ｃ
上記ブルー分散液の調製に使用したミセル形成成分の代わりにイソブチルエステルを部分的に含むスチレン−マレイン酸共重合体（Ｓｉｇｍａ−Ａｌｄｒｉｃｈ Ｃｏ．）を使用した点を除き、上記ブルー分散液の調製手順と同じ手順を試みた。この比較例を試みる前に、イソブチルエステルを部分的に含むスチレン−マレイン酸共重合体３００ｍｇを脱イオン水５ｍＬに、５％水酸化リチウム溶液を滴下して溶解した。得られた溶液のｐＨを標準ｐＨ試験紙で調べた結果は１０であった。溶液に５分間超音波処理を行って均一にしたのち、Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で粒子径の測定を試みた。しかし試料の測定はできなかったので、ミセルが形成されたという証拠は得られなかった。
【００６５】
イソブチルエステルを部分的に含むスチレン−マレイン酸共重合体３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｂｌｕｅ ＢＣ １２ｇおよびＮ−メチル−２−ピロリドン５００ｍＬを３Ｌビーカー中で混合した。混合物を７０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理を行っても均一な溶液は得られなかった。混合物を上から激しく攪拌しながら、水酸化テトラメチルアンモニウム５水和物２５ｇをエタノール１Ｌに溶解した溶液を加えた。塩基溶液の添加によって不均一なブルーの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体をトリフルオロメタンスルホン酸リチウム２０ｇを含む脱イオン水３００ｇに加えた。大きなブルーの結晶を含む混合物が得られ、それは４時間攪拌しても均一にはならなかった。超音波処理を行っても効果は認められなかった。１０ミクロンのステンレス製メッシュを通して濾過すると、ブルーの結晶とほとんど無色の濾液とに分離された。均一な分散液が得られなかったので、この試料をそれ以上評価することはできなかった。
【００６６】
比較例 分散液Ｄ
上記ブラック分散液の調製に使用したミセル形成成分の代わりにスチレンスルホン酸−マレイン酸共重合体のナトリウム塩の遊離酸（Ｓｉｇｍａ−Ａｌｄｒｉｃｈ Ｃｏ．）３０ｇを使用した点を除き、上記ブラック分散液の調製手順と同じ手順を試みた。スチレンスルホン酸−マレイン酸共重合体のナトリウム塩４０ｇを脱イオン水５００ｇに溶解し、強酸性イオン交換樹脂Ｄｏｗｅｘ ５０ＷＸ２−２００ ３５０ｇを充填したイオン交換樹脂カラムに流した。溶出液を回転式蒸発器で濃縮して水を除き、固体を減圧乾燥した。この比較試験を試みる前に、乾燥した固体３００ｍｇを脱イオン水５ｍＬに、５％水酸化リチウム溶液を滴下して溶解した。得られた溶液のｐＨを標準ｐＨ試験紙で調べた結果は１０であった。溶液に５分間超音波処理を行って均一にしたのち、Ｐｈｏｔａｌ Ｏｔｓｕｋａ Ｅｌｅｃｔｒｏｎｉｃｓ製ＥＬＳ−８００フォトン相関光度計で粒子径の測定を試みた。しかし試料の測定はできなかったので、ミセルが形成されたという証拠は得られなかった。スチレンスルホン酸−マレイン酸共重合体のナトリウム塩の遊離酸３０ｇ、Ｉｎｄａｎｔｈｒｅｎ Ｂｌａｃｋ ＡＣ ２０ｇおよびジメチルスルホキシド５００ｍＬを３Ｌビーカー中で混合した。混合物を６０゜Ｃに加熱し、攪拌機で上から２時間激しく攪拌した。次に、ビーカーを超音波装置に移し、３０分間超音波処理を行った。この処理を行っても均一な溶液は得られなかった。混合物を上から激しく攪拌しながら、水酸化テトラメチルアンモニウム５水和物２５ｇをエタノール１Ｌに溶解した溶液を加えた。塩基溶液の添加によって不均一なブラックの固体が沈殿した。混合物を１６時間放置すると固体は上澄液ときれいに分離した。傾斜法で大部分の上澄液を除き、残りを１００ｍＬ遠沈管に入れ、３５００ｒｐｍで１時間遠心分離した。固体をトリフルオロメタンスルホン酸リチウム２０ｇを含む脱イオン水３００ｇに加えた。大きなブラックの結晶を含む混合物が得られ、それは４時間攪拌しても均一にはならなかった。超音波処理を行っても効果は認められなかった。１０ミクロンのステンレス製メッシュを通して濾過すると、ブラックの結晶とほとんど無色の濾液とに分離された。均一な分散液が得られなかったので、この試料をそれ以上評価することはできなかった。
【００６７】
インクの評価
下記のようにして、表１に記載したインクの信頼性、普通紙および専用紙に対するカラーガマット、耐光性、耐オゾン性、耐水性、耐湿性および耐摩擦性を評価した。
【００６８】
連続印字信頼性の試験
連続印字条件下における上記のインクの信頼性を以下のように評価した。まず、熱シールアルミニウムパックにインクを充填し、脱気を行ってから密封した。次に、そのインクをプリンタＰＭ−９００Ｃ（セイコーエプソン社の製品名）の黒インクプリントヘッドに装填した。インクがすべてのノズルから正しい方向に噴射される（ノズルから噴射されるインクの液滴の角偏差は約±０．５゜以内）ことを最初に確認するために、すべてのノズルを使用してラインパターンを印字した。印字パターンを、Ａ４用紙一杯に印字する３６０ｄｐｉのソリッドブロックパターンに切り替え、印字速度を毎分約４枚の速い速度に設定した。それからブロックパターンを用紙５０００枚に連続印字した。試験した４種類のインクすべてについて、すべてのノズルは良好な方向性を示し、印字抜けしたノズルは、５０００枚すべての用紙について全く認められなかった。
【００６９】
長期保管信頼性の試験
上記インクをプリントヘッドに長期間保管した時の信頼性を以下のようにして評価した：まず、インクを脱気したのち、熱シールアルミニウムパックに封入した。次に、プリンタＭＪ−５１０（セイコーエプソン社の製品名）の黒インクプリントヘッドに装填した。インクがすべてのノズルから正しい方向に噴射されることを最初に確認するためにすべてのノズルを使用してラインパターンを印字した。次に、インク供給部をプリントヘッドから取り去り、次いでプリンタからプリントヘッドを外した。キャップを外したプリントヘッドを恒温槽中に４０゜Ｃで４日間保管した。再びプリントヘッドをプリンタに取り付け、それからインク供給部をプリンタヘッドに取り付けた。プリンタのクリーニング操作を実行してからすべてのノズルを使用してラインパターンを印字した。すべてのノズルが正しい方向に印字するまで、クリーニング操作とラインパターンの印字をくり返した。試験した４種類のインク全部について完全に回復するまでに必要なクリーニング操作の回数は４回以下であった。これは信頼性が合格レベルにあることを示している。
【００７０】
熱サイクル信頼性の試験
上記インクの両極端の温度（−３０゜Ｃ〜６０゜Ｃ）に対する信頼性を以下のように評価した。まず、インクを脱気して３０ｍＬのガラス製試料瓶に封入した。試料瓶を６０゜Ｃの恒温槽中に入れ、同温度で２４時間保管した。試料を恒温槽から−３０゜Ｃの定温冷凍庫に移し、同温度で２４時間保管した。全部で１０回のサイクルが終了するまで、両温度間のサイクルをくり返した。最後のサイクルが終了した後、インクを室温で解凍し、ガラス試料瓶を静かに上下反転させた。試料瓶の底に沈殿がないか検査した。試験した４種類のインク全部について沈殿は認められなかった。これは信頼性が合格レベルにあることを示している。
【００７１】
カラーガマットの評価
Ｓｐｅｃｔｒｏｓｃａｎテーブルユニットを備えたＧｒｅｔａｇ−ＭａｃｂｅｔｈのＳｐｅｃｔｒｏｌｉｎｏを使ってＣＩＥＬＡＢ色測定評価を行うための標準色パッチを普通用紙と専用紙上に印字した。普通紙の代表としてＸｅｒｏｘ ４０２４（ゼロックス社製）を使用した。専用紙の代表にはエプソン社のプレミアム半光沢フォト紙を使用した。プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用して本発明の４種類のインクを印字した。水溶性染料を使って調製される染料をベースにしたインクの代表としてプリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０用の標準インクを使用した。顔料をベースにしたインクの代表としてプリンタＳｔｙｌｕｓ Ｐｈｏｔｏ ２０００Ｐ（セイコーエプソン社の製品名）用の標準インクを使用し、同じプリンタで印字した。上記２種類の用紙におけるガマット値を表２に示す。表から分かるように、本発明のインクは両用紙に対して、水溶性染料を使って調製される染料をベースにした対応するインクと同等以上の彩度を示している。表２から分かるように、本発明のインクは、市販の顔料をベースにしたインクよりも普通用紙に対して広いカラーガマットを有している。また、専用紙に対する本発明のインクのカラーガマットは、顔料をベースにした同じ市販のインクと同じカラーガマットを有する。
【００７２】
【表２】

【００７３】
表中、ＳＣ ９８０はプリンタ：Ｓｔｙｌｕｓ Ｃｏｌｏｒ ９８０を、
ＳＰ ２０００Ｐはプリンタ：Ｓｔｙｌｕｓ Ｐｈｏｔｏ ２０００Ｐを示す。
【００７４】
耐光性試験
プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用し、エプソン社のプレミアム半光沢フォト紙に本発明の４種類のインクを使って標準色パッチを印字した。一晩乾燥させた後、色パッチをガラスでカバーしたフレームに装着した。次いでフレームに装着した試験片を５．４Ｋｌｕｘの蛍光褪色ユニットに取り付けた。ユニットの環境を温度２４゜Ｃで、相対湿度６０％に設定した。Ｓｐｅｃｔｒｏｓｃａｎテーブルユニットを備えたＧｒｅｔａｇ−ＭａｃｂｅｔｈのＳｐｅｃｔｒｏｌｉｎｏを使って、褪色させた色パッチのＣＩＥＬＡＢ測色値△Ｅを測定し、露光しなかった色パッチと比較した。４，８，１２，１６および２０週間経過した時点で各試験片を取り出して△Ｅ値を測定した。△Ｅ値をＫｌｕｘ・時間に対してプロットして得られる曲線は、４種類の色すべてについて直線を与えた。△Ｅ値カットオフ値を７、そして平均１日露光量を５Ｋｌｕｘ時間として４種類のインクすべての耐光性を計算した結果、６０年以上と出た。この値は、従来のカラー写真で得られる最高の値と同等かそれ以上である。したがって、本発明のインクは高水準の耐光性を有するものと判定される。
【００７５】
耐オゾン性試験
プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用し、本発明の４種類のインクで、エプソン社のプレミアム半光沢フォト紙に標準色パッチを印字した。Ｓｔｙｌｕｓ Ｃｏｌｏｒ ９８０を使用して、染料をベースにしたプリンタ標準インクで、また、Ｓｔｙｌｕｓ Ｐｈｏｔｏ ２０００Ｐ（セイコーエプソン社の製品名）を使用して、顔料をベースにしたプリンタ標準インクで、同じ用紙に比較用の色パッチを印字した。一晩乾燥させた後、色パッチをガラスでカバーしないフレームに装着した。それから、フレームに装着した試験片をオゾン曝露室に入れた。オゾン室の環境を温度２４゜Ｃ、相対湿度６０％、オゾン濃度０．４００ｐｐｍに設定した。Ｓｐｅｃｔｒｏｓｃａｎテーブルユニットを備えたＧｒｅｔａｇ−ＭａｃｂｅｔｈのＳｐｅｃｔｒｏｌｉｎｏを使って、褪色させた色パッチのＣＩＥＬＡＢ測色値△Ｅを測定し、曝露しなかった色パッチと比較した。２，４および６日間、そして１，２，３，４，６，８および１０週間経過した時点で各試験片を取り出して△Ｅ値を測定した。各インクセットの４種類の色すべてについて△Ｅ値対時間のデータが得られた。△Ｅ値を時間に対してプロットして得られる曲線は、最初の４または５測定点の間は急傾斜で上昇し、それ以降は次第に直線的な上昇に変化した。本発明のすべてインクで最終的な△Ｅ値は１０より小さかった。染料をベースにしたインクのセットを比較すると、シアンの褪色が特に目立ち、最終的な△Ｅ値は３０より大きかった。顔料をベースにしたインクのセットを比較すると、シアンの褪色が特に目立ち、最終的な△Ｅ値は１５より大きかった。本発明のインクについてもある程度のオゾン褪色が認められたが、その程度は市販の染料をベースにしたインクおよび顔料をベースにしたインクより小さかった。したがって本発明のインクは高水準の耐オゾン性を有するものと判定される。
【００７６】
耐水性試験
プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用し、本発明の４種類のインクで、Ｘｅｒｏｘ ４０２４普通紙に標準色パッチ（２ｃｍ×２ｃｍ）を印字した。一晩乾燥させたのち、使い捨て１ｍＬピペットを使って脱イオン水１滴を各パッチの中心部に注意深く付着させた。２４時間乾燥させたのち、試験片を目で観察した。４種類の色すべてについて、色パッチ上の印字されていない外側への色の移動は認められなかった。したがって、本発明のインクは高水準の耐水性を有するものと判定される。
【００７７】
耐湿性試験
プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用し、本発明の４種類のインクで、エプソン社のプレミアム半光沢フォト紙に標準色パッチを印字した。２４時間乾燥させたのち、カラーパッチをガラスでカバーしないフレームに装着した。それから、フレームに装着した試験片を湿気試験室に入れた。湿気試験室の環境を温度２４゜Ｃ、相対湿度７０％に設定した。Ｓｐｅｃｔｒｏｓｃａｎテーブルユニットを備えたＧｒｅｔａｇ−ＭａｃｂｅｔｈのＳｐｅｃｔｒｏｌｉｎｏを使って、湿気に曝露した色パッチのＣＩＥＬＡＢ測色値△Ｅを測定し、曝露しなかった色パッチと比較した。１０，２０，４０，６０および８０日間経過した時点で各試験片を取り出して△Ｅ値を測定した。サンプリング時間に対する△Ｅ値の上昇はわずかであった。４種類の色すべてに対して、データを対数回帰分析によってフィットさせて得られた△Ｅ値は、５０年間の湿気への曝露で６より小さい値となった。したがって本発明のインクは高水準の耐湿性を有するものと判定される。
【００７８】
耐摩擦性試験
プリンタＳｔｙｌｕｓ Ｃｏｌｏｒ ９８０（セイコーエプソン社の製品名）を使用し、本発明の４種類のインクで、エプソン製プレミアム半光沢フォト専用紙にテキストサンプルを印字した。２４時間乾燥させたのち、黄色マーカーペン（ゼブラペン２）を使ってテキストの同じ部分を２回連続してこすった。こすった時の概略の圧力を測定するため、摩擦操作は天秤上で行った。摩擦する圧力は２回とも３００ｇで誤差は±５０ｇであった。４種類の色すべてについて、印字されていない部分への色の転写は認められなかった。したがって本発明のインクは高水準の耐摩擦性を有するものと判定される。[0001]
[Field of the Invention]
The present invention provides a reliable recorded image and a durable recorded image having a chroma (chroma) equal to or better than the corresponding ink based on a dye prepared using an aqueous dye. The present invention relates to a water-based ink composition used for inkjet recording, which is applied to special paper and plain paper.
[0002]
[Prior art]
Inkjet recording is a non-impact recording method in which a printer forms ink droplets in response to digital signals generated by a computer, for example. The ink droplets are attached to a substrate such as paper or transparent film. Inkjet printers are widely accepted commercially due to their high print quality, low cost, relatively low noise during use, and good graphics rendering. Heated (inkjet) and piezoelectric drop-on-demand printers have been very successful on the market and are widely used in offices and homes as printers for personal computers.
[0003]
Inks used in inkjet printers can be classified into dye-based inks and pigment-based inks. In general, dye-based inks have a very wide color gamut on special paper and a medium color gamut on plain paper. Dye-based inks give satisfactory results for many applications, but are generally defined herein as light resistance, ozone resistance, water resistance, moisture resistance and rub resistance. The overall durability is poor. Since the recorded document is required to have a certain storability, the low durability of the recorded image with the dye-based ink is an important problem.
[0004]
On the other hand, in the case of inks based on pigments, it is possible to prepare inks that are more preferable than inks based on dyes in order to produce a highly durable recording document with sufficient storage stability. Durable inks based on pigments having a fairly wide color gamut relative to special paper are known in the prior art. Unfortunately, however, this type of ink based on pigments is known to have a much narrower color gamut for plain paper than the corresponding inks based on dyes. Similarly, durable inks based on pigments are also known to have a moderate color gamut to plain paper. Unfortunately, such inks based on pigments are known to have a much narrower color gamut for specialty papers than the corresponding inks based on dyes. In other words, a pigment-based ink composition that has a saturation equal to or greater than that of the corresponding ink based on a dye and that provides a durable recorded image not only on dedicated paper but also on plain paper. It is not known that the preparation method has been clarified.
[0005]
One type of dye that can provide a durable image is a vat dye. Since vat dyes are excellent in light resistance, ozone resistance, water resistance and moisture resistance, they are used for dyeing textile products. In the standard form on the market, vat dyes do not dissolve in water at all. This standard form is often referred to as the oxidized form. Unless otherwise noted, the term “viscosity dye” as used herein refers to a standard oxidized form. Since vat dyes are oxidized and do not dissolve in water, they cannot be used in water-based inks as they are. On the other hand, reduced vat dyes called leuco salts or leuco bases are water-soluble. Reduction to the soluble leuco salt / base form is routinely performed using sodium hydrosulfite or sodium borohydride in an aqueous alkaline solution. Reduced soluble leuco salt / base form is highly susceptible to air oxidation, so it will remain in a reduced state unless special measures are taken, such as strict exclusion of oxygen in the air or the use of sacrificial reducing agents I can't do it.
[0006]
Since vat dyes are dyes based on the nature of their color, they give images not only on special paper but also on plain paper that have a saturation equivalent to or higher than the corresponding aqueous inks based on dyes. Can do. In contrast, for pigments that develop color from both solid state interactions and individual molecular absorption, the saturation of the resulting image is generally inferior to that obtained with the corresponding dye. The poor saturation of pigment-based inks can be easily seen with two widely used pigments, quinacridone red or phthalocyanine blue in high concentrations. The reason for such poor saturation is that the color of these types of pigments is highly dependent on solid state interactions.
[0007]
Since vat dyes are excellent in intrinsic saturation and durability, several inks based on vat dyes have been reported. These examples will be described in detail below.
[0008]
Japanese Laid-Open Patent Publication No. 57-18767 discloses a recording liquid containing a vat dye and / or a sulfur dye. Specifically, it is described that a vat dye and / or a sulfur dye is dissolved in a liquid medium in the presence of a reducing agent that gives a leuco salt / base type. After dissolution, the dissolved reducing dye is oxidized to form a vat dye and / or sulfur dye dispersion in the liquid medium. JP-A-57-18767 claims a dispersant as a component of the recording liquid. Examples of preferred dispersants are polymeric dispersants having a molecular weight in the range of 1000 to 100,000 g / mole, such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl pyridine, sodium polyacrylate, polymethacrylate, condensed naphthalene sulfonate. , Styrene-maleic acid copolymer, di-isobutylene-maleic acid copolymer, polyethylene glycol, polypropylene glycol, polyoxyethylene-oxydipropylene block copolymer, styrene- (meth) acrylic acid copolymer, (meta ) Acrylate ester- (meth) acrylate copolymer, styrene-itaconate copolymer, itaconate-itaconate copolymer, vinylnaphthalene-maleate copolymer, vinylnaphthalene- (meta Acrylic acid co Coalescence, vinyl naphthalene - itaconate copolymer are mentioned. In the polymer dispersant of the above example, the following monomers can also be used for modification of the polymer dispersant: acrylonitrile, vinyl acetate, (meth) acrylamide, N-methylol- (meth) acrylamide, vinyl chloride, Vinylidene chloride and ethylene.
[0009]
The inventor of the present invention will obtain a stable dispersion of vat dye according to the method described in JP-A-57-18767, ie, Examples 1, 2A, 2C and 2D. I tried. In Example 1, SMA 1440 manufactured by Atofina Chemicals was used in place of the Arco Chemicals product described in the specification. In Examples 2A and 2C, the same dispersant as described in the specification was used. In Example 2D, the corresponding polyacrylic acid sodium salt from Sigma-Aldrich was used in place of the Sannobuco product described in the specification. As a result of performing Examples 1 and 2C, a precipitate of a large crystalline vat dye was formed immediately upon addition of the hydrogen peroxide solution as the oxidizing agent. This precipitation also occurred when the hydrogen peroxide solution was dropped over several hours. The crystals were easily separated at 3000 rpm using a laboratory tabletop centrifuge. In short, in experiments conducted by the inventors, it was impossible to obtain a stable vat dye dispersion in the presence of the dispersants described in Examples 1 and 2C. In the follow-up experiment of Example 2A, a vat dye containing solids was precipitated when hydrogen peroxide was added in aqueous methanol and recycled with a KSIF type colloid mill manufactured by Premier Mill (Redding, Pa., USA). A stable dispersion could not be obtained using the pump. Even after milling for several hours, a stable dispersion was not obtained. In short, in experiments conducted by the inventors, it was impossible to obtain a stable vat dye dispersion in the presence of the described dispersant used in Example 2A. In the follow-up experiment of Example 2D, a vat dye containing solids was precipitated when hydrogen peroxide was added in aqueous methanol, and a stable dispersion could not be obtained with a laboratory ball mill. After milling with a ball mill for 24 hours, the mixture was pressure filtered through a 5 micron membrane filter to give a substantially colorless filtrate. In short, in experiments conducted by the inventors, it was not possible to obtain a stable vat dye dispersion in the presence of the described dispersant used in Example 2D. The reason why a stable dispersion could not be obtained is not clear, but in any case, it should be noted that there is no detailed description in the specific example of Japanese Patent Application Laid-Open No. 57-18767. I must. Except for ultrafiltration conditions, important experimental details are omitted. In particular, there is no description regarding the conditions of ultracentrifugation, the conditions of milling using a colloid mill, the particle size of the dispersed vat dye, and the concentration of the dispersed vat dye after being subjected to ultracentrifugation.
[0010]
JP 63-139959 claims an ink containing water, an organic solvent, a solubilized vat dye and an antioxidant. The solubilized vat dye used in JP-A-63-139959 is different from ordinary vat dyes in that it contains a sulfonic acid group that imparts solubility. It has been. A recorded matter using the ink of the present invention is expected to have the chroma advantage of dye-based ink. However, since the dye described in JP-A-63-139959 is water-soluble, it is not expected to have the advantage of durability of vat dye, particularly in terms of water resistance and moisture resistance.
[0011]
Japanese Patent Laid-Open No. 63-139961 claims an ink containing water, an organic solvent, a vat dye leuco salt and an antioxidant. The vat dye leuco salt is obtained by reducing a corresponding standard form of vat dye. The role of the antioxidant component is to maintain the vat dye in a reduced soluble leuco salt form. A recorded matter using the ink of the present invention is expected to have the chroma advantage of dye-based ink. However, the reduced soluble dye described in JP-A-63-139961 is easily oxidized by air, and once the antioxidant (sacrificial reducing agent) in the ink is consumed by air oxidation, the reduced dye is used. Will be oxidized to the corresponding standard oxidized insoluble form. If this happens, the nozzles of the printer head are clogged, and it is expected that reliable recording quality cannot be obtained.
[0012]
Japanese Laid-Open Patent Publication No. 1-93389 describes a recording method using an ink jet printer. According to this recording method, the ink containing a vat dye is a reduced soluble leuco salt type. In the invention of this recording method, in the second stage, a liquid containing an oxidant is recorded at the top of the formed image, and the reduced vat dye is oxidized to a standard oxidized form. A recorded matter using the ink of the present invention is expected to have the chroma advantage of dye-based ink. However, from the standpoint of printer design and cost, it is undesirable to require two separate liquids. In addition, as pointed out above, reduced soluble dyes are susceptible to air oxidation, and the reduced dye is oxidized to the corresponding insoluble form. If this happens, it is expected that the nozzles of the printer head will be clogged and reliable print quality will not be obtained.
[0013]
[Problems to be solved by the invention]
As described above, with a corresponding ink based on a dye that provides reliable printing performance and is prepared using a water-soluble dye not only for special paper but also for plain paper. There is a need for an aqueous ink composition for use in recording by use in ink jets that provides a durable recorded image with equal or greater saturation. Specifically, there is a need for inks based on vat dyes that take advantage of the inherent saturation and durability of vat dyes that do not have the problems of the prior art described above.
[0014]
[Means for Solving the Problems]
The object of the present invention is to provide reliable printing performance and corresponding inks based not only on special paper but also on plain paper and prepared using water-soluble dyes. An object of the present invention is to provide a water-based ink composition used for ink jet recording, which gives a durable recorded image having a saturation equal to or higher than that.
[0015]
According to the invention described herein,
(A) water as the main solvent;
(B) at least one vat dye;
(C) Components forming at least one micelle
A water-based ink composition for use in ink jet recording is provided.
[0016]
The micelle-forming component in the ink forms micelles having an average diameter of more than 20 nm and less than 150 nm as measured by photon correlation spectroscopy in an aqueous solution having a pH value higher than 8. In addition, the micelle forming component exists as a polyanion in an aqueous solution having a pH value higher than 8. The ink according to the present invention comprises 0.1 to 10% vat dye, 0.1 to 40% micelle forming component, and 50 to 99.8% aqueous carrier medium, the aqueous carrier medium comprising: A mixture of water, a co-solvent miscible with water, a water-soluble surfactant, and a water-soluble additive.
[0017]
The ink of the present invention has excellent reliability in ink jet recording and provides a recorded image having good light resistance, ozone resistance, water resistance, moisture resistance and friction resistance. In addition, the ink of the present invention is not only for exclusive paper but also for plain paper. A recorded image having a saturation equal to or higher than that of a corresponding ink based on a dye prepared using a water-soluble dye. give.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The ink composition of the present invention is suitable for use in an inkjet printer using a known method of ejecting ink through a plurality of nozzles mounted on a printer head. The ink composition of the present invention can also be used for a writing instrument such as a pen in which the ink use conditions are not as strict as those of an ink jet printer.
[0019]
Vat dye
The vat dyes of the present invention comprise at least one vat dye selected from the group of those standard oxidized forms of vat dyes. Vat dyes can be classified into either indigo type or anthraquinone type. The present invention does not distinguish between these two. Examples of the vat dyes of the present invention include the following dyes listed in the color index: C.I. I. Vat Yellow 2, C.I. I. Vat Yellow 4, C.I. I. Vat Yellow 10, C.I. I. Vat Yellow 20, C.I. I. Vat Yellow 33, C.I. I. Vat Orange 1, C.I. I. Vat Orange 2, C.I. I. Vat Orange 3, C.I. I. Vat Orange 5, C.I. I. Vat Orange 7, C.I. I. Vat Orange 9, C.I. I. Vat Orange 13, C.I. I. Vat Orange 15, C.I. I. Vat Red 1, C.I. I. Vat Red 2, C.I. I. Vat Red 10, C.I. I. Vat Red 13, C.I. I. Vat Red 15, C.I. I. Vat Red 16, C.I. I. Vat Red 31, C.I. I. Vat Red 41, C.I. I. Vat Red 42, C.I. I. Vat Red 45, C.I. I. Vat Red 47, C.I. I. Vat Red 52, C.I. I. Vat Violet 1, C.I. I. Vat Violet 2, C.I. I. Vat Violet 9, C.I. I. Vat Violet 13, C.I. I. Vat Violet 21, C.I. I. Vat Blue 1, C.I. I. Vat Blue 3, C.I. I. Vat Blue 4, C.I. I. Vat Blue 5, C.I. I. Vat Blue 6, C.I. I. Vat Blue 8, C.I. I. Vat Blue 12, C.I. I. VatBlue 14, C.I. I. Vat Blue 18, C.I. I. Vat Blue 19, C.I. I. Vat Blue 20, C.I. I. Vat Blue 29, C.I. I. Vat Blue 35, C.I. I. Vat Blue 41, C.I. I. Vat Blue 64, C.I. I. Vat Green 1, C.I. I. VatGreen 2, C.I. I. Vat Green 3, C.I. I. Vat Green 8, C.I. I. Vat Green 9, C.I. I. Vat Brown 1, C.I. I. Vat Brown 3, C.I. I. Vat Brown 22, C.I. I. Vat Brown 25, C.I. I. Vat Brown 41, C.I. I. Vat Brown 44, C.I. I. Vat Brown 46, C.I. I. Vat Brown 57, C.I. I. Vat Brown 68, C.I. I. Vat Brown 72, C.I. I. Vat Black 8, C.I. I. Vat Black 9, C.I. I. Vat Black 13, C.I. I. Vat Black 14, C.I. I. Vat Black 20, C.I. I. Vat Black 25, C.I. I. Vat Black 27, C.I. I. Vat Black 29, C.I. I. Vat Black 36, C.I. I. Vat Black 56, C.I. I. Vat Black 57, C.I. I. Vat Black 59 and C.I. I. Vat Black 60. The vat dyes of the present invention include the following commercially available vat dyes: Indanthren Yellow 5G, Indanthren Orange 3R, Indanthren Red 3B, Indanthren Blue BC (C.I. Vat Blue 6), Indanthren V3 Indanthren Green XBN, Indanthren Olive B, Indanthren Brown BR (CI Vat Brown 1), Indanthren Navy DB, Indanthren Black AC. The list given above is not exhaustive and other vat dyes should be considered within the scope of the present invention. Preferred vat dyes for preparing the dispersions of the present invention are to some extent in highly polar organic solvents such as dimethyl sulfoxide, sulfolane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide and hexamethylphosphoramide. It is a vat dye with solubility.
[0020]
The amount of vat dye in the ink composition of the present invention is preferably 0.1 to 10% by weight.
[0021]
Micellar forming ingredients
The aqueous inkjet ink composition includes at least one micelle-forming component. The micelle-forming component may be of any chemical composition as long as it satisfies the following conditions: (1) A micelle is formed in an aqueous solution having a pH value higher than 8, and its average diameter is photon. Greater than 20 nm and less than 150 nm as determined by correlation spectroscopy, and (2) present as a polyanion in an aqueous solution having a pH value greater than 8.
[0022]
For the ink of the present invention, an aqueous ink composition having a pH value higher than 8 is preferred. The reason is that such ink compositions are not corrosive to parts of inkjet printers that are susceptible to corrosion. Also for the inks of the present invention, aqueous ink compositions having a pH value below about 10 are preferred. The reason is that it is safe for the human body and chemically gentle to the material of the ink jet printer that can come into contact with the ink.
[0023]
In order to be a preferred aqueous inkjet ink composition having a pH value higher than 8, the aqueous vat dye dispersion must be stable at a pH value higher than 8. The conditions for the micelle-forming components are specified for aqueous solutions with a pH value higher than 8 because of the stability of the dispersion.
[0024]
In order to obtain a stable aqueous vat dye dispersion, the inventor of the present invention forms micelles in an aqueous solution whose pH value is higher than 8, and is measured by photon correlation spectroscopy. It was found that the average diameter must be greater than 20 nm and less than 150 nm. The average diameter of the micelle-forming component may be measured by any known method, but photon correlation spectroscopy is preferred from the viewpoint of rapidity, simplicity and reproducibility. Instruments for measuring particle size by photon correlation spectroscopy are commercially available from many manufacturers. The concentration range measurable with photon correlation spectroscopy is in all cases above the critical micelle concentration (cmc) for substances that can form micelles with an average diameter greater than 20 nm.
[0025]
Therefore, it is important to consider whether a certain substance forms micelles having an average diameter larger than 20 nm, which is the lower limit, rather than being in the cmc.
[0026]
The lower limit of 20 nm set for the micelle forming component of the present invention is that a normal anionic surfactant such as sodium oleate forms a stable aqueous vat dye dispersion according to the preparation method used in the present invention. Based on the observation that no. Common anionic surfactants such as sodium oleate form micelles with an average diameter of less than 10 nm in aqueous solutions with pH values higher than 8. As described in the section “Prior Art”, ordinary polymer dispersants did not form stable aqueous vat dye dispersions when used in the preparation process of the present invention. This is consistent with the present invention in that ordinary aqueous polymer dispersants do not form micelles in aqueous solutions with pH values higher than 8, according to the results measured by photon correlation spectroscopy.
[0027]
The upper limit of 150 nm set for the micelle-forming component of the present invention is that (1) it is necessary to maintain good saturation for the recorded image, and (2) the dispersed vat dye particles This is based on the need to minimize sedimentation. First, with respect to maintaining a wide color gamut, it is well known that the saturation decreases when the particle size of the dye is significantly greater than about 100 nm. For micelles containing no dye with an average diameter of 150 nm, the size of the dye in the corresponding micelle containing the dye is expected to be less than 150 nm. Therefore, in order to increase the saturation as much as possible, a micelle forming component that forms micelles having an average diameter of less than 150 nm is preferable. A micelle-forming component that forms micelles having an average diameter of less than 120 nm is more preferred. With regard to the second point, i.e., to reduce the amount of sedimentation as much as possible, small particles have a slower sedimentation rate than large particles if all other conditions are equal. Since the density of all commercially available vat dyes is larger than that of the aqueous support medium, the pigment particle size is preferably smaller than 150 nm in order to minimize the sedimentation rate. In order to minimize sedimentation, a micelle-forming component that forms micelles having an average diameter of less than 150 nm is preferred. A micelle-forming component that forms micelles having an average diameter of less than 120 nm is more preferred.
[0028]
The inventors of the present invention have discovered that to obtain a stable aqueous vat dye dispersion, the micelle-forming component must be present as a polyanion in an aqueous solution with a pH value higher than 8. Within this restriction, polyanions are designated, differing from nonions and polycations. The reason for being limited to polyanions is unknown, but two points can be mentioned. First, unlike nonionic micelle-forming components, charged (polyanionic or polycationic) micelles are more stable than nonionic micelles. This is because the charged portion of the polyanionic or polycationic micelle forming component is more strongly solvated in the aqueous support medium than the hydrophilic portion of the nonionic micelle forming component. Secondly, unlike the polycationic micelle-forming component, the polyanionic micelle is more stable in an aqueous solution having a pH value higher than 8. This is because the charged portion of the polyanionic micelle-forming component is more stable than that of the polycationic micelle-forming component in an alkaline solution. In contrast, in an acidic solution, the charged portion of the polycationic micelle forming component is more stable than that of the polyanionic micelle forming component. The polarity of the micelle-forming component and the magnitude of the charge may be measured by any known method, but since this component has a strong tendency to form micelles, it is difficult to measure the individual molecules of the component. Therefore, for example, in addition to the characterization of mutually independent structures of micelle-forming components by NMR, IR, HPLC, the usual chemical methods using known pKa data for dissociative functional groups, for example, are applied. Thus, it is preferable to determine that the micelle forming component is present as a polyanion in an aqueous solution having a pH value higher than 8.
[0029]
A general structural formula of one type of compound that satisfies the conditions for the micelle-forming component of the present invention is shown below:
[0030]
[Chemical 1]

Where m is an average value for the polydisperse polystyrene block and is in the range of 10 to 20; p is an average value for the polydisperse (meth) acrylate and is in the range of 20 to 40; and Z is hydrogen (H) Or methyl group (CH _Three ). The above two-block copolymer can be prepared by a known method or a commercial product can be purchased. The following document: Zhong, X. F. , Varshney, S .; N. And Eisenberg, A .; , Macromolecules, 1992, 25, 7160-7167 and Cao, T .; Munk, P .; Ramireddy, C.I. Tuzar, Z .; Webber, S .; E. , Macromolecules, 1991, 24, 6300 to 6310, describes the method. This type of diblock copolymer is available from Polymer Source Inc. (Canada, Quebec, Dorval). As can be seen from the chemical structure of the above compound, this compound exists as a polyanion because the carboxyl group of poly (meth) acrylate undergoes multiple dissociation in an aqueous solution having a pH value higher than 8.
[0031]
Another type of general structural formula for compounds that satisfy the conditions for the micelle-forming components of the present invention is as follows:
[0032]
[Chemical 2]

Where x is an average value for polydisperse oligosaccharides and is in the range of 1 to 14; n is in the range of 2 to 12; R is aryl, substituted aryl, alkylaryl, substituted alkylaryl, pyridyl or carbon atom It is a substituted pyridyl group having a number of 5 to 20. As is apparent from the above chemical structure, this compound exists as a polyanion because the carboxyl group of the oligosaccharide component undergoes multiple dissociation in an aqueous solution having a pH value higher than 8.
[0033]
The oligosaccharide moiety of the above compound can be easily obtained from natural polysaccharides such as alginic acid and pectin using chemical or enzymatic methods. The simplest way to obtain the above compounds is to use two reductive amination reactions. The first reductive amination reaction is performed using an oligosaccharide precursor and an excess amount of a branched polyamine compound represented by the following general formula.
[0034]
[Chemical 3]

Here, n is in the range of 2-12. Branched polyamines with n = 4 are commercially available under the name “Astramol Am4” from DSM New Business Development (Netherlands). After removing the excess branched amine, the product obtained in the first reductive amination and the general formula R—CHO, where R is aryl, substituted aryl, alkylaryl, substituted alkylaryl, pyridyl or carbon atom A second reductive amination reaction is carried out using an excess of aldehyde represented by the number 5 to 20 substituted pyridyl groups. Examples of preferred aldehydes that can be used to prepare this type of micelle-forming component are listed below, but it goes without saying that this list is not exhaustive. Preferred aldehydes: pipeonal, 2,3- (methylenedioxy) benzaldehyde, 1-naphthalaldehyde, 2-naphthalaldehyde, 4-methoxy-1-naphthalaldehyde, 4-biphenylcarboxaldehyde, 3-phenoxybenzaldehyde, 4-phenoxybenzaldehyde, 2- Fluorene carboxaldehyde, 3-benzyloxybenzaldehyde, 4-benzyloxybenzaldehyde, 3- (4-methoxyphenoxy) benzaldehyde, 9-anthraldehydride, 2-benzyloxy-3-methoxybenzaldehyde, 3-benzyloxy-4-methoxybenzaldehyde And 4-benzyloxy-3-methoxybenzaldehyde.
[0035]
The amount of vat dye in the ink composition of the present invention is preferably 0.1 to 40% by weight of micelle forming component.
[0036]
water
Water is the main solvent of the aqueous ink composition of the present invention. As water, deionized water is usually used. The “aqueous carrier medium” as used in the present invention means a mixture of water, a cosolvent miscible with water, a water-soluble surfactant, and a water-soluble additive. A preferred amount of the aqueous carrier medium in the ink composition of the present invention is 50 to 99.8% by weight.
[0037]
Cosolvent miscible with water
The ink compositions of the present invention can include one or more water-miscible cosolvents according to the formulation of the ink formulation best done by those skilled in the art. Organic cosolvents that are miscible with water are well known, and examples are as follows: (1) alcohols such as isopropyl alcohol and butyl alcohol; (2) ketones such as acetone and methyl ethyl ketone; (3) Ethers such as tetrahydrofuran and dioxane, (4) Esters such as ethyl acetate and propylene carbonate, (5) Ethylene glycol, glycerol, glycerol ethoxylate, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, tetraethylene Polyhydric alcohols such as glycol, 1,2-pentanediol, 1,2-hexanediol, polyethylene glycol, polypropylene glycol, 1,2,6-hexatriol, thioglycol, (6) die Alkyl ethers of polyhydric alcohols such as lenglycol-mono-n-butyl ether, triethylene glycol-mono-n-butyl ether, diethylene glycol-mono-n-hexyl ether, dipropylene glycol monomethyl ether, (7) urea, Nitrogen-containing compounds such as pyrrolidone and N-methyl-2-pyrrolidone, and (8) sulfur-containing compounds such as dimethyl sulfoxide and tetramethylene sulfoxide. It goes without saying that the above list is not exhaustive and does not limit the ink formulation of the present invention. In other words, other cosolvents can be used and are within the scope of the present invention.
[0038]
Water-soluble surfactant
The ink composition of the present invention may contain one or more water-soluble surfactants according to the formulation of the ink formulation best done by those skilled in the art. In general, nonionic surfactants are preferred in that they do not foam. Examples of useful surfactants are as follows: acetylene-based diol ethylene oxide adduct, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, higher alkylamine ethylene oxide adduct, ethylene oxide propylene oxide Polymer and polyether modified dimethylpolysiloxane. It goes without saying that the above list is not exhaustive and does not limit the ink formulation of the present invention. In other words, other surfactants can be used and are within the scope of the present invention.
[0039]
Other ingredients
In order to obtain an ink composition having a pH value higher than 8, in addition to the components described above, one or more bases can optionally be added to the ink. Preferred bases include inorganic bases, organic bases and mixtures thereof. Examples of suitable bases are: lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, ammonia, methylamine, dimethylamine, trimethylamine, morpholine, N-methylmorpholine, mono Ethanolamine, diethanolamine, triethanolamine, triisopropanolamine, N-methylmonoethanolamine, N, N-dimethylmonoethanolamine, N-methyldiethanolamine and tetramethylammonium hydroxide. In addition to the base additive, a pH buffer, bactericidal agent, corrosion inhibitor, viscosity modifier, ultraviolet absorber and antioxidant can be optionally added to the ink. There is no particular restriction on the total amount of other components used in the ink. The amounts of all components of the ink are selected so that the surface tension of the ink is in the range of about 20 to 40 dyne / cm and the viscosity of the ink is in the range of about 1.0 to 10.0 mPa · s.
[0040]
Ink preparation
The ink composition of the present invention can theoretically be prepared by any known method. However, as pointed out above, the method of using the reduced soluble leuco salt / base form of the vat dye did not give a stable dispersion in the hands of the inventor. The method that can be used to prepare the stable vat dye dispersion of the present invention shares the common use of the standard oxidized form of the vat dye. Specifically, standard oxidized vat dye solutions in strongly polar organic solvents such as dimethyl sulfoxide, sulfolane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide and hexamethylphosphoramide are used. Is done.
[0041]
In one useful method, first, at least one vat dye and at least one micelle-forming component are partially or completely dissolved in a highly polar organic solvent. The micelle forming component is dissolved in a free acid / non-dissociated form. In general, these micelle-forming components are completely dissolved in highly polar organic solvents under these conditions. The degree to which the starting vat dye is soluble in a highly polar organic solvent depends on the type of vat dye and the cosolvating ability of the micelle-forming component. After homogenization by stirring, milling, heating, sonication or a combination of these methods, a solid containing both the vat dye and the micelle-forming component precipitates when an appropriate solvent is added. Useful precipitation solvents in the present invention include alcohols and ketones, and the specific choice depends on the types of vat dyes and micelle-forming components. After the solid is precipitated, it is dispersed in the aqueous base solution by stirring, milling, heating, sonication or a combination of these methods. The amount of base in the aqueous solution should be sufficient to neutralize the free acid / non-dissociated form of the micelle forming component and to make the dispersion have a pH value greater than 8 and less than 10. Preferred bases for preparing the aqueous base solution can include inorganic bases, organic bases and mixtures thereof. Examples thereof are listed in the section “Other components” above.
[0042]
In another useful method, which is similar in many respects to the above method, first, at least one vat dye and at least one micelle-forming component are dissolved in a highly polar organic solvent. As mentioned above, the micelle forming component is dissolved in a free acid / non-dissociated form. Uniform by stirring, milling, heating, sonication or a combination of these methods. When uniform, slowly add the non-aqueous base solution to the homogeneous solution. Depending on the type of the micelle-forming component, the base in the non-aqueous base solution, and the strongly polar organic solvent, this addition can produce a solid precipitate containing both the vat dye and the micelle-forming component. The amount of the non-aqueous solution is sufficient to neutralize the free acid / non-dissociated form of the micelle forming component. If a solid precipitates, it is separated and dispersed in an aqueous base solution by stirring, milling, heating, sonication or a combination of these methods. When the solid does not precipitate, it is necessary to add a suitable solvent to precipitate. As noted above, useful precipitation solvents of the present invention are alcohols and ketones. After the solid is precipitated, it is dispersed in an aqueous base solution by stirring, milling, heating, sonication or a combination of these methods.
[0043]
The vat dye dispersion obtained by either of the above two methods may be concentrated and / or purified by known methods prior to use in formulating ink for use in an ink jet printer. A useful method for concentration and purification is the ultrafiltration method. By carefully selecting the pore size of the ultrafiltration membrane, soluble impurities including excess micelle-forming components and excess base are forced through the ultrafiltration membrane and collected in the effluent reservoir. It is generally desirable to filter the dispersion or ink formulation to remove insoluble components that are not dispersed. Both metal mesh filters and membrane filters can be used. In order to perform filtration, the dispersion may be pressurized, or the receiver end of the filtration device may be depressurized. Centrifugation can also be performed to remove large particles that can cause clogging of nozzles installed in the printer head of an inkjet printer. Once a purified and concentrated vat dye dispersion is obtained, the desired ingredients are mixed according to the order considered to be effective and the ink is formulated. When the blending of the ink is finished, filtration is performed again depending on the blending.
[0044]
While not intending to be bound by theory, it is believed that a stable vat dye dispersion can be obtained according to the method of the present invention for several reasons. The first reason is that the micelle-forming components specified according to the claims of the present invention are used as a special type of dispersing means. Micellar-forming components that meet the criteria that an average particle size of greater than 20 nm must be formed in an aqueous solution are limited to polymers composed of two different blocks for any practical purpose. One of the different blocks is a polyelectrolyte in aqueous solution and the other block is a relatively high molecular weight hydrophobic compound. When dissolved in an aqueous solution, these macromolecules assemble themselves to form uniform spherical micelles, in which the insoluble hydrophobic blocks are sequestered in the micelle core and are soluble polyelectrolytes. The block forms a shell that keeps the micelles dispersed in solution. These special micelle types are superficially similar to the well-known detergent micelles, but the micelles are much larger and much more stable. Since standard oxidized vat dyes are hydrophobic substances that do not dissolve in water, they have a strong affinity for similar hydrophobic substances. Again, without intending to be bound by theory, the stability of these vat dye dispersions is that hydrophobic vat dyes have a strong affinity for the large hydrophobic core of the micelles of the present invention. It seems to bring the advantage of greatly contributing to
[0045]
A second reason for obtaining a stable vat dye dispersion is believed to be that the hydrophobic vat dye is included in the hydrophobic core of the micelle as a hydrophobic species. According to the method of the present invention, at least one hydrophobic vat dye and at least one micelle-forming component are dissolved in a highly polar solvent. The two blocks of the micelle-forming polymer of the present invention have such a large difference that weak polymer self-association can occur even in a highly polar organic solvent. Due to the high polarity of organic solvents, macromolecular self-association is assumed to consist of the same type as self-association in aqueous solutions, ie, a strongly solvated shell of a hydrophobic core and a hydrophilic portion. Most vat dyes of standard oxidation type are not very soluble in non-aqueous polar organic solvents in the presence of the micelle-forming components of the present invention, but a uniform solution is obtained. Again, although not intending to be bound by theory, it is clear that hydrophobic vat dyes have a strong affinity for the hydrophobic core of micelles. It seems to bring a considerable advantage of greatly contributing to solubility.
[0046]
The third reason why a stable vat dye dispersion can be obtained is that micelles that contain a hydrophobic vat dye in a hydrophobic core migrate from a highly polar organic medium to an aqueous solution. It seems that it is sometimes stored. In the first method, the precipitation solvent is added after a homogeneous solution is obtained. Alcohols and ketones, the types of solvents used for this purpose, are not expected to break the micelle core. In the second method, a non-aqueous base solution is added after a uniform solution is obtained. This addition converts the free acid / non-dissociated portion of the micelles to the polyelectrolyte form, resulting in the unchanged micelles being precipitated. It is not expected that this type of precipitation will break the micelle core. Again, though not intending to be bound by theory, it is a stable vat dye that a micelle that has not undergone a change containing a hydrophobic vat dye in the hydrophobic core can be transferred from an organic solvent to an aqueous solution. It seems to bring the advantage of greatly contributing to the preparation of the dispersion.
[0047]
【Example】
The present invention will be further clarified by the following specific examples. All work was carried out in a well-ventilated drafter.
[0048]
Micellar forming component
A micelle forming component represented by the following general formula was prepared as follows:
[0049]
[Formula 4]

In the formula, the average value x of the polydisperse oligosaccharide moiety is 5; n is 4; and R is 1-naphthyl.
[0050]
150 g of alginic acid (ultra-low viscosity alginic acid; Kibun Food Chemifa, Japan) was added to 500 mL of deionized water in a 2000 mL beaker to form a slurry. While mechanically stirring from above with a stirrer, 28.2 g of lithium hydroxide monohydrate was added to this slurry. Further deionized water was added to bring the total volume of the solution to 600 mL. 100 g of 34.5 wt% aqueous hydrogen peroxide was added and the resulting solution was stirred for 4 hours and then allowed to stand for 16 hours. Next, 1 mL of n-nonanol as an antifoaming agent and 40 mL of a solution containing 0.65 g of ferrous sulfate heptahydrate prepared freshly were added to the alginate / hydrogen peroxide aqueous solution with stirring. The solution was stirred vigorously for 4 hours. During this time, a significant exotherm occurred and then subsided. 45 g of 34.5% by weight aqueous hydrogen peroxide was added and the resulting solution was stirred for a short time, followed by standing for 16 hours. The mixture was then heated to 50 ° C. until a mild exotherm occurred and the solution color changed to dark. The dark-colored solution was allowed to cool to room temperature, and Whatman filter paper no. Filter using 1. The filtrate was transferred to a 1 L eggplant flask and concentrated with a rotary evaporator connected to a recirculation aspirator until the liquid volume reached 300 mL. The water temperature of the rotary evaporator was maintained at about 55 ° C. The dark concentrated solution was transferred to a 1 L beaker and washed with water to a total liquid volume of 350 mL. When 350 mL of glacial acetic acid was added while vigorously stirring this solution, a fluffy precipitate was formed. The mixture was sonicated for 30 minutes and then left for 16 hours. The mixture was centrifuged on a tabletop centrifuge to separate the solids. A part of the solid was transferred to four 100 mL centrifuge tubes and centrifuged at 3500 rpm for 1 hour. After discarding the supernatant, the remaining portion that had not been centrifuged was transferred to the above four centrifuge tubes, and the centrifuge tube that had become full was centrifuged at 3500 rpm for 1 hour. All solids were transferred to a 1 L polypropylene container by rinsing with 100 mL water. The polypropylene container was sealed and placed in a constant temperature dryer at 60 ° C. for 16 hours. Next, absolute ethanol was slowly added with vigorous stirring until the total volume reached 1L. The mixture was passed through Whatman filter paper no. Filtered through 1. The damp solid was washed with 95% ethanol and left to dry in the air. Finally, the solid was dried under reduced pressure until a constant weight was reached. The yield of product was 20 g. The procedure was repeated 6 times to synthesize a total of about 120 g of product. The average degree of polymerization of the oligosaccharide is P.I. A. Shaffer and M.M. Determined by the method of Somogyi (J. Biol. Chem. 1933, 100, 695-713). Galacturonic acid monohydrate recrystallized from ethanol and water was used as a reference standard for monosaccharides for this method. The average degree of polymerization of the oligosaccharide sample was 7. In the above formula, the value of x corresponding to the average degree of polymerization is 5.
[0051]
The polyanionic nature of the oligosaccharides described above is J. et al. Simms, A.M. T.A. Hotchkiss, Jr. , P.M. L. Irwin and K.M. B. This was confirmed using high performance liquid chromatography (HPLC) according to the method described in Hicks, Carbohydrate Research, 1995, 278, 1-9. Using a Hewlett-Packard 1100 series high performance liquid chromatograph, the sample was eluted from a Cyclobond I column (Tokyo Kasei, 250 mm x 4.6 mm) with acetonitrile-sodium phosphate buffer (pH 5) 50:50 as the mobile phase. I let you. Oligosaccharide peaks corresponding to a degree of polymerization of 3 to 10 were observed, and it was confirmed that the oligosaccharide component behaves as a polyanion at pH 5. From the physicochemical principle, it is estimated that this behavior does not change even in an aqueous solution having a pH value higher than 8. Similarly, it is presumed that the micelle-forming component prepared from this oligosaccharide by the method described in detail later behaves as a polyanion in an aqueous solution having a pH value higher than 8.
[0052]
120 g of the oligosaccharide prepared above and 75 g of the branched polyamine “Astramol Am4” (DSM New Business Development, The Netherlands) were dissolved in 500 mL of deionized water in a 5 L beaker. Without covering the beaker, the beaker was left in a fume hood for 5 days. While stirring vigorously from above with a stirrer, 33 g of sodium borohydride was added to this viscous solution. After stirring for 8 hours, the solution was left for 16 hours. Next, methanol was slowly added with vigorous stirring until the total volume reached 5L. A fluffy yellow solid precipitated by the addition of methanol. When the mixture was allowed to stand for 16 hours, the solids were considerably deposited. The supernatant was removed by the gradient method. Methanol was added while stirring the mixture vigorously until the total volume was 5L. The mixture was again left for 16 hours to deposit solids. The supernatant was removed by the gradient method so that the amount of methanol remaining in the solid slurry was as small as possible.
[0053]
While stirring, 1.5 L of dimethyl sulfoxide and 70 g of 1-naphthaldehyde were added to the slurry prepared above. The slurry was heated to 55 ° C., stirred for 6 hours and then left for 16 hours. Next, 200 mL of a methanol solution of tetraethylammonium cyanoborohydride prepared by metathesis in methanol from 25 g of 95% sodium cyanoborohydride and 70 g of tetraethylammonium chloride was added while vigorously stirring the mixture. The mixture was stirred for 8 hours and then left for 16 hours. Next, 350 mL of a methanol solution of tetraethylammonium cyanoborohydride prepared by metathesis in methanol from 100 g of 1-naphthalaldehyde, 40 g of 95% sodium cyanoborohydride and 105 g of tetraethylammonium chloride was added. While stirring the mixture vigorously, trifluoroacetic acid was added dropwise until all solids were just dissolved. The weight of the dropped trifluoroacetic acid was approximately 140 g. The brownish yellow solution was stirred for 8 hours and then allowed to stand for 16 hours. The solution was stirred for an additional 10 hours while the solution was heated to 55 ° C. and then allowed to stand for 16 hours. While stirring the solution vigorously, 95% ethanol was added until the total volume of the mixture was 5L. A fluffy yellowish white precipitate was formed as the alcohol was added. The beaker was covered and left for 40 hours. Most of the supernatant was removed by a gradient method, and the remaining mixture was placed in a 100 mL centrifuge tube and centrifuged at 3000 rpm for 30 minutes to separate the solid. The separated wet solid was suspended in boiling methanol for 30 minutes. The mixture was cooled to room temperature and the product was suction filtered through a fine (pore size 16-40 microns) glass filter. The solid was washed several times with methanol and then dried in air. Finally, the solid was dried under reduced pressure until a constant weight was reached. The product yield was 210 g.
[0054]
300 mg of the dried solid was placed in 5 mL of deionized water and 5% lithium hydroxide was added dropwise to dissolve. The pH of the solution examined with standard pH test paper was 10. The particle size of the micelle forming component was measured with an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics and then uniformed by irradiating with ultrasonic waves for 5 minutes. The measured particle size was 78 nm.
[0055]
Dispersion adjustment
Yellow dispersion
30 g of micelle forming component (prepared above), 16 g of Indanthren Yellow 5G (obtained from Australia, NSW 2031, Randwick, Batik Oetero) and 400 mL of dimethyl sulfoxide are mixed in a 3 L beaker, heated to 70 ° C. with stirrer Stir vigorously for 2 hours from above. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. A uniform solution was obtained by this treatment. While stirring the mixture vigorously from above, isopropyl alcohol was added to a total volume of 2.5L. A yellow solid precipitated by the addition of isopropyl alcohol. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 5 g of lithium hydroxide monohydrate. The mixture was stirred with a magnetic stirrer for 2 hours to obtain a uniform dispersion. The dispersion was sonicated for 15 minutes and then filtered through a 5 micron membrane filter to remove a small amount of insoluble matter. The pH of the dispersion at this point measured with a pH meter was 11.5. Excess lithium hydroxide, isopropyl alcohol and dimethyl sulfoxide were removed from the dispersion by ultrafiltration using a laboratory Millipore Minitan equipped with 10,000 NMWL low binding regenerated cellulose filter plates (10). Deionized water (1500 mL) was added to the dispersion in several portions to compensate for the loss of waste solution. After the final deionized water was added, the dispersion was concentrated to a volume of about 80 mL. Next, deionized water was added dropwise to adjust the weight of the dispersion to 128 g. The pH of the produced yellow dispersion was 9.5. The particle diameter measured by an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics was 101 nm.
[0056]
Red dispersion
30 g of micelle forming component (prepared above), 15 g of Indanthren Red 3B (obtained from Australia, NSW 2031, Randwick, Batik Otero) and 500 mL of N-methyl-2-pyrrolidone were mixed in a 3 L beaker. The mixture was heated to 70 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. A uniform solution was obtained by this treatment. While the mixture was vigorously stirred from above, 95% ethanol was added to bring the total volume to 3L. The addition of 95% ethanol precipitated a red solid. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 5 g of lithium hydroxide monohydrate. The mixture was stirred with a magnetic stirrer for 2 hours to obtain a uniform dispersion. The dispersion was sonicated for 15 minutes and then filtered through a 5 micron membrane filter to remove a small amount of insoluble matter. The pH of the dispersion at this point measured with a pH meter was 11.7. Ultrafiltration using a laboratory Millipore Minitan equipped with 10,000 NMWL low-binding regenerated cellulose filter plates (10 sheets) removed excess lithium hydroxide, ethanol and N-methyl-2-pyrrolidone from the dispersion. . Deionized water (1500 mL) was added to the dispersion in several portions to compensate for the loss of waste solution. After the final deionized water was added, the dispersion was concentrated to a volume of about 75 mL. Next, deionized water was added dropwise to adjust the weight of the dispersion to 125 g. The pH of the produced red dispersion was 9.5. The particle diameter measured by ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics was 98 nm.
[0057]
Blue dispersion
30 g of the micelle forming component (prepared above), 12 g of Indanthren Blue BC (obtained from Australia, NSW 2031, Randwick, Batik Oetero) and 500 mL of N-methyl-2-pyrrolidone were mixed in a 3 L beaker. The mixture was heated to 70 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. A uniform solution was obtained by this treatment. While the mixture was vigorously stirred from above, a solution of 25 g of tetramethylammonium hydroxide pentahydrate in 1 L of ethanol was added. A blue solid precipitated upon addition of the base solution. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 20 g of lithium trifluoromethanesulfonate. The mixture was stirred with a magnetic stirrer for 2 hours to obtain a uniform dispersion. The dispersion was sonicated for 15 minutes and then filtered through a 5 micron membrane filter to remove a small amount of insoluble matter. The pH of the dispersion at this point measured with a pH meter was 11.6. Excess lithium salt, tetramethylammonium salt, ethanol and N-methyl-2-pyrrolidone were removed from the dispersion using a laboratory Millipore Minitan equipped with 10,000 NMWL low binding regenerated cellulose filter plates (10 sheets). Deionized water (1500 mL) was added to the dispersion to compensate for the waste solution loss. After the final deionized water was added, the dispersion was concentrated to a volume of about 70 mL. Next, deionized water was added dropwise to adjust the weight of the dispersion to 120 g. The pH of the resulting blue dispersion was 9.5. The particle diameter measured by an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics was 91 nm.
[0058]
Black dispersion
30 g of the micelle forming component (prepared above), 20 g of Indanthren Black AC (obtained from NSW 2031, Randwick, Batik Otero, Australia) and 500 mL of dimethyl sulfoxide were mixed in a 3 L beaker. The mixture was heated to 60 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. A uniform solution was obtained by this treatment. While the mixture was vigorously stirred from above, a solution of 25 g of tetramethylammonium hydroxide pentahydrate in 1 L of ethanol was added. A black solid precipitated upon addition of the base solution. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 20 g of lithium trifluoromethanesulfonate. The mixture was stirred with a magnetic stirrer for 2 hours to obtain a uniform dispersion. The dispersion was sonicated for 15 minutes and then filtered through a 5 micron membrane filter to remove a small amount of insoluble matter. The pH of the dispersion at this point measured with a pH meter was 11.5. Excess lithium salt, tetramethylammonium salt, ethanol and dimethyl sulfoxide were removed from the dispersion using a laboratory Millipore Minitan equipped with 10,000 NMWL low binding regenerated cellulose filter plates (10 sheets). Deionized water (1500 mL) was added to the dispersion to compensate for the waste solution loss. After the final deionized water was added, the dispersion was concentrated to a volume of about 90 mL. Next, deionized water was added dropwise to adjust the weight of the dispersion to 135 g. The pH of the produced black dispersion was 9.5. The particle diameter measured by an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics was 106 nm.
[0059]
General ink preparation
While stirring, the ingredients listed in Table 1 below were added to the beaker in the order listed. The combined mixture was stirred for 3 hours. The mixture was then filtered through a 5 micron membrane filter to obtain an ink suitable for an inkjet printer. In Table 1, the following abbreviations are used: water = W; glycerol = GLY; 2-pyrrolidone = 2P; triethylene glycol = TEG; triethylene glycol mono-n-butyl ether = TEG-mBE; Surfynol 465 ( Product name of Air Products Inc) = S465. The measured viscosity values of the four types of ink when the density was 1.08 g / mL were all 4.2 mPa · s.
[0060]
[Table 1]

[0061]
In the table, numerical values in parentheses indicate addition amounts (g).
[0062]
Comparative example
Comparative Example Dispersion A
The same procedure as that for preparing the yellow dispersion was tried, except that 30 g of Joncryl 682 (product name of Johnson Polymers Inc.) was used instead of the micelle-forming component used for the preparation of the yellow dispersion. Before attempting this comparative example, 300 mg of Joncryl 682 l was dissolved in 5 mL of deionized water by dropwise addition of a 5% lithium hydroxide solution. The result of examining the pH of the obtained solution with a standard pH test paper was 10. After sonicating the solution for 5 minutes to make it uniform, measurement of the particle size was attempted with an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics. However, because the sample could not be measured, there was no evidence that micelles were formed.
30 g of Joncryl 682, 16 g of Indanthren Yellow 5G and 400 mL of dimethyl sulfoxide were mixed in a 3 L beaker. The mixture was heated to 70 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. Even with this treatment, a uniform solution was not obtained. While stirring the mixture vigorously from above, isopropyl alcohol was added to a total volume of 2.5L. A heterogeneous yellow solid precipitated upon addition of isopropyl alcohol. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 5 g of lithium hydroxide monohydrate. A mixture containing large yellow crystals was obtained, which did not become homogeneous after stirring for 4 hours. No effect was observed even when sonication was performed. Filtration through a 10 micron stainless mesh separated into yellow crystals and an almost colorless filtrate. This sample could not be further evaluated because a uniform dispersion could not be obtained.
[0063]
Comparative Example Dispersion B
The same procedure as the preparation of the red dispersion was tried, except that 30 g of Demol AS free acid (Kao product name) was used instead of the micelle-forming component used for the preparation of the red dispersion. 50 g of Demol AS was dissolved in 500 g of deionized water and passed through an ion exchange resin column packed with 300 g of strongly acidic ion exchange resin Dowex 50WX2-200. The eluate was concentrated with a rotary evaporator to remove water, and the solid was dried under reduced pressure. Before conducting this comparative experiment, 300 mg of the dried solid was dissolved in 5 mL of deionized water by dropwise addition of a 5% lithium hydroxide solution. The result of examining the pH of the obtained solution with a standard pH test paper was 10. After sonicating the solution for 5 minutes to make it uniform, measurement of the particle size was attempted with an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics. However, because the sample could not be measured, there was no evidence that micelles were formed. 30 g of Demol AS free acid, 15 g of Indanthren Red 3B and 500 mL of N-methyl-2-pyrrolidone were mixed in a 3 L beaker. The mixture was heated to 70 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. Even with this treatment, a uniform solution was not obtained. While the mixture was vigorously stirred from above, 95% ethanol was added to bring the total volume to 3L. A heterogeneous red solid precipitated by the addition of 95% ethanol. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 5 g of lithium hydroxide monohydrate. A mixture containing large red crystals was obtained, which did not become homogeneous after stirring for 4 hours. No effect was observed even when sonication was performed. Filtration through a 10 micron stainless mesh separated into red crystals and an almost colorless filtrate. This sample could not be further evaluated because a uniform dispersion could not be obtained.
[0064]
Comparative Example Dispersion C
Preparation procedure of the blue dispersion except that a styrene-maleic acid copolymer (Sigma-Aldrich Co.) partially containing isobutyl ester was used instead of the micelle forming component used for the preparation of the blue dispersion. Tried the same procedure. Before attempting this comparative example, 300 mg of a styrene-maleic acid copolymer partially containing isobutyl ester was dissolved in 5 mL of deionized water by dropwise addition of a 5% lithium hydroxide solution. The result of examining the pH of the obtained solution with a standard pH test paper was 10. After sonicating the solution for 5 minutes to make it uniform, measurement of the particle size was attempted with an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics. However, because the sample could not be measured, there was no evidence that micelles were formed.
[0065]
30 g of a styrene-maleic acid copolymer partially containing isobutyl ester, 12 g of Indanthren Blue BC and 500 mL of N-methyl-2-pyrrolidone were mixed in a 3 L beaker. The mixture was heated to 70 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. Even with this treatment, a uniform solution was not obtained. While the mixture was vigorously stirred from above, a solution of 25 g of tetramethylammonium hydroxide pentahydrate dissolved in 1 L of ethanol was added. A heterogeneous blue solid precipitated upon addition of the base solution. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 20 g of lithium trifluoromethanesulfonate. A mixture containing large blue crystals was obtained, which did not become homogeneous after stirring for 4 hours. No effect was observed even when sonication was performed. Filtration through a 10 micron stainless steel mesh separated into blue crystals and an almost colorless filtrate. This sample could not be further evaluated because a uniform dispersion could not be obtained.
[0066]
Comparative Example Dispersion D
Except for using 30 g of the free acid of sodium salt of styrenesulfonic acid-maleic acid copolymer (Sigma-Aldrich Co.) instead of the micelle forming component used for the preparation of the black dispersion, The same procedure as the preparation procedure was attempted. 40 g of a sodium salt of a styrene sulfonic acid-maleic acid copolymer was dissolved in 500 g of deionized water, and passed through an ion exchange resin column packed with 350 g of a strongly acidic ion exchange resin Dowex 50WX2-200. The eluate was concentrated with a rotary evaporator to remove water, and the solid was dried under reduced pressure. Before attempting this comparative test, 300 mg of the dried solid was dissolved in 5 mL of deionized water by dropwise addition of a 5% lithium hydroxide solution. The result of examining the pH of the obtained solution with a standard pH test paper was 10. After sonicating the solution for 5 minutes to make it uniform, measurement of the particle size was attempted with an ELS-800 photon correlation photometer manufactured by Photo Otsuka Electronics. However, because the sample could not be measured, there was no evidence that micelles were formed. 30 g of free acid of sodium salt of styrene sulfonic acid-maleic acid copolymer, 20 g of Indanthren Black AC and 500 mL of dimethyl sulfoxide were mixed in a 3 L beaker. The mixture was heated to 60 ° C. and stirred vigorously with a stirrer for 2 hours from the top. Next, the beaker was moved to an ultrasonic device and subjected to ultrasonic treatment for 30 minutes. Even with this treatment, a uniform solution was not obtained. While the mixture was vigorously stirred from above, a solution of 25 g of tetramethylammonium hydroxide pentahydrate dissolved in 1 L of ethanol was added. A heterogeneous black solid precipitated upon addition of the base solution. The mixture was allowed to stand for 16 hours and the solid separated cleanly from the supernatant. Most of the supernatant was removed by the gradient method, and the rest was placed in a 100 mL centrifuge tube and centrifuged at 3500 rpm for 1 hour. The solid was added to 300 g of deionized water containing 20 g of lithium trifluoromethanesulfonate. A mixture containing large black crystals was obtained, which did not become homogeneous after stirring for 4 hours. No effect was observed even when sonication was performed. Filtration through a 10 micron stainless steel mesh separated into black crystals and an almost colorless filtrate. This sample could not be further evaluated because a uniform dispersion could not be obtained.
[0067]
Ink evaluation
In the following manner, the reliability of the ink described in Table 1, the color gamut, the light resistance, the ozone resistance, the water resistance, the moisture resistance and the rub resistance against plain paper and special paper were evaluated.
[0068]
Continuous printing reliability test
The reliability of the above ink under continuous printing conditions was evaluated as follows. First, a heat-sealed aluminum pack was filled with ink, deaerated, and then sealed. Next, the ink was loaded into a black ink print head of a printer PM-900C (product name of Seiko Epson Corporation). Use all nozzles to first verify that ink is ejected in the correct direction from all nozzles (the angular deviation of the ink droplets ejected from the nozzles is within about ± 0.5 °) A line pattern was printed. The print pattern was switched to a 360 dpi solid block pattern for printing on a full A4 sheet, and the print speed was set to a high speed of about 4 sheets per minute. Then, a block pattern was continuously printed on 5000 sheets of paper. For all four ink types tested, all nozzles showed good orientation and no missing nozzles were observed on all 5000 sheets.
[0069]
Long-term storage reliability test
The reliability when the ink was stored in the print head for a long time was evaluated as follows: First, the ink was deaerated and then sealed in a heat-sealed aluminum pack. Next, it was loaded into a black ink print head of a printer MJ-510 (product name of Seiko Epson Corporation). A line pattern was printed using all nozzles to initially verify that ink was ejected from all nozzles in the correct direction. Next, the ink supply unit was removed from the print head, and then the print head was removed from the printer. The print head with the cap removed was stored in a thermostatic bath at 40 ° C. for 4 days. The print head was again attached to the printer, and then the ink supply unit was attached to the printer head. A line pattern was printed using all nozzles after the printer cleaning operation. The cleaning operation and line pattern printing were repeated until all nozzles printed in the correct direction. The total number of cleaning operations required to fully recover all four ink types tested was four or less. This indicates that the reliability is at an acceptable level.
[0070]
Thermal cycle reliability test
The reliability of the ink with respect to the extreme temperatures (-30 ° C to 60 ° C) was evaluated as follows. First, the ink was degassed and sealed in a 30 mL glass sample bottle. The sample bottle was placed in a constant temperature bath at 60 ° C. and stored at the same temperature for 24 hours. The sample was transferred from the thermostat to a constant temperature freezer at −30 ° C. and stored at the same temperature for 24 hours. The cycle between both temperatures was repeated until a total of 10 cycles were completed. After the last cycle was completed, the ink was thawed at room temperature and the glass sample bottle was gently inverted upside down. The bottom of the sample bottle was inspected for precipitation. No precipitation was observed for all four inks tested. This indicates that the reliability is at an acceptable level.
[0071]
Evaluation of color gamut
Standard color patches for CIELAB color measurement evaluation using Gretag-Macbeth's Spectrolino equipped with a Spectroscan table unit were printed on plain paper and special paper. Xerox 4024 (manufactured by Xerox Corporation) was used as a representative of plain paper. Epson's premium semi-gloss photo paper was used as a representative of the special paper. The printer Stylus Color 980 (product name of Seiko Epson Corporation) was used to print the four inks of the present invention. Standard ink for the printer Stylus Color 980 was used as a representative of dye-based inks prepared using water-soluble dyes. A standard ink for a printer Stylus Photo 2000P (product name of Seiko Epson Corporation) was used as a representative of pigment-based ink, and printing was performed with the same printer. Table 2 shows the gamut values for the two types of paper. As can be seen from the table, the inks of the present invention exhibit saturation on both papers that is equal to or greater than the corresponding inks based on dyes prepared using water-soluble dyes. As can be seen from Table 2, the ink of the present invention has a wider color gamut for plain paper than the commercial pigment-based ink. Also, the color gamut of the ink of the present invention for dedicated paper has the same color gamut as the same commercially available ink based on pigment.
[0072]
[Table 2]

[0073]
In the table, SC 980 is a printer: Stylus Color 980,
SP 2000P indicates a printer: Stylus Photo 2000P.
[0074]
Light resistance test
Using a printer Stylus Color 980 (product name of Seiko Epson), standard color patches were printed on Epson's premium semi-gloss photo paper using the four inks of the present invention. After drying overnight, the color patch was mounted on a glass covered frame. The test piece mounted on the frame was then attached to a 5.4 Klux fluorescent amber unit. The environment of the unit was set at a temperature of 24 ° C. and a relative humidity of 60%. The CIELAB colorimetric value ΔE of the faded color patch was measured using a Gretag-Macbeth Spectrolino equipped with a Spectroscan table unit and compared with the unexposed color patch. When 4, 8, 12, 16, and 20 weeks passed, each test piece was taken out and the ΔE value was measured. The curve obtained by plotting the ΔE value against Klux · time gave straight lines for all four colors. The light resistance of all four types of ink was calculated with a ΔE value cut-off value of 7 and an average daily exposure amount of 5 Klux time, resulting in over 60 years. This value is equal to or higher than the highest value obtained with conventional color photography. Therefore, it is determined that the ink of the present invention has a high level of light resistance.
[0075]
Ozone resistance test
Using a printer Stylus Color 980 (product name of Seiko Epson Corporation), standard color patches were printed on Epson premium semi-gloss photo paper with the four inks of the present invention. Compare to the same paper with standard printer ink based on dyes using Stylus Color 980 and standard printer ink based on pigments using Stylus Photo 2000P (product name of Seiko Epson) A color patch was printed. After drying overnight, the color patches were mounted on a frame that was not covered with glass. The test piece attached to the frame was then placed in an ozone exposure chamber. The environment of the ozone chamber was set to a temperature of 24 ° C., a relative humidity of 60%, and an ozone concentration of 0.400 ppm. Using a Gretag-Macbeth Spectrolino equipped with a Spectroscan table unit, the CIELAB colorimetric value ΔE of the faded color patch was measured and compared to the unexposed color patch. Each test piece was taken out for 2, 4 and 6 days, and when 1, 2, 3, 4, 6, 8 and 10 weeks passed, and the ΔE value was measured. Data for ΔE values versus time were obtained for all four colors of each ink set. The curve obtained by plotting the ΔE value against time increased with a steep slope during the first 4 or 5 measurement points, and thereafter gradually changed to a linear increase. The final ΔE value for all inks of the present invention was less than 10. When comparing dye-based ink sets, the cyan fade was particularly noticeable and the final ΔE value was greater than 30. When comparing pigment-based ink sets, the cyan amber color was particularly noticeable and the final ΔE value was greater than 15. Some degree of ozone fading was also observed for the inks of the present invention, but to a lesser extent than commercial dye-based inks and pigment-based inks. Therefore, it is determined that the ink of the present invention has a high level of ozone resistance.
[0076]
Water resistance test
A standard color patch (2 cm × 2 cm) was printed on Xerox 4024 plain paper with the four types of inks of the present invention using a printer Stylus Color 980 (product name of Seiko Epson Corporation). After drying overnight, a drop of deionized water was carefully attached to the center of each patch using a disposable 1 mL pipette. After drying for 24 hours, the specimens were observed visually. For all four colors, no unprinted color movement on the color patch was observed. Therefore, it is determined that the ink of the present invention has a high level of water resistance.
[0077]
Moisture resistance test
Using a printer Stylus Color 980 (product name of Seiko Epson Corporation), standard color patches were printed on Epson premium semi-gloss photo paper with the four inks of the present invention. After drying for 24 hours, the color patch was attached to a frame not covered with glass. Then, the test piece attached to the frame was placed in the moisture test chamber. The environment of the humidity test chamber was set to a temperature of 24 ° C. and a relative humidity of 70%. The CIELAB colorimetric value ΔE of a color patch exposed to moisture was measured using a Gretag-Macbeth Spectrolino equipped with a Spectroscan table unit and compared to an unexposed color patch. At the time when 10, 20, 40, 60 and 80 days passed, each test piece was taken out and the ΔE value was measured. The increase in ΔE value with respect to the sampling time was slight. For all four colors, the ΔE value obtained by fitting the data by logarithmic regression analysis was less than 6 after 50 years of exposure to moisture. Therefore, it is determined that the ink of the present invention has a high level of moisture resistance.
[0078]
Friction resistance test
Using a printer Stylus Color 980 (product name of Seiko Epson Corporation), text samples were printed on Epson premium semi-glossy photo paper with the four inks of the present invention. After drying for 24 hours, the same part of the text was rubbed twice in succession using a yellow marker pen (Zebra Pen 2). The friction operation was performed on a balance to measure the approximate pressure when rubbed. The rubbing pressure was 300 g in both cases, and the error was ± 50 g. For all four colors, no color transfer to the unprinted area was observed. Therefore, it is determined that the ink of the present invention has a high level of friction resistance.

Claims (7)

(A) water as the main solvent;
(B) at least one vat dye;
(C) at least one micelle-forming component ;
Ri consists of,
The micelle forming component has the general formula

Where m is the average value for the polydisperse polystyrene block and is in the range of 10 to 20; p is the average value for the polydisperse (meth) acrylate and is in the range of 20 to 40; and Z is hydrogen (H)? It is a methyl group (CH ₃ )
and

Where x is an average value for the polydisperse oligosaccharide and is in the range of 1 to 14;
n is in the range of 2 to 12; R is aryl, substituted aryl, alkylaryl, substituted alkylaryl, pyridyl or a substituted pyridyl group having 5 to 20 carbon atoms
Aqueous ink-jet ink composition, wherein at least one Der Rukoto of a compound represented by.   The micelle-forming component forms micelles in an aqueous solution having a pH value higher than 8, and its average diameter measured by photon correlation spectroscopy is greater than 20 nm and smaller than 150 nm. Ink composition.   The ink composition according to claim 1, wherein the micelle-forming component is present as a polyanion in an aqueous solution having a pH value higher than 8. The ink comprises 0.1 to 10% vat dye, 0.1 to 40% micelle forming component, and 50 to 99.8% aqueous carrier medium;
The ink composition according to claim 1, wherein the aqueous carrier medium is a mixture of water, a co-solvent miscible with water, a water-soluble surfactant, and a water-soluble additive.   A recording method comprising attaching the ink according to any one of claims 1 to 4 to a recording medium.   An ink jet recording method comprising ejecting the ink droplets according to claim 1 to adhere to a recording medium.   A recorded matter recorded by the method according to claim 6.