JP2004195706A - Recording liquid, recording method using the liquid, and recording equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording method which is almost free from a cockling phenomenon despite the use of a soaking-type ink and allows an high quality level image to be printed on a paper as is the case with the use of a laser printer, in an ink jet recording process by which ink droplets are spurted as fine liquid droplets from a fixed head by thermal energy or mechanical energy and deposited on a material on which an image is recorded for recording, and an ink composition. <P>SOLUTION: This ink jet recording method spurts the ink droplets from the fixed head by the thermal energy or mechanical energy as fine liquid droplets and thereby, deposits the fine liquid droplets on the material on which an image is recorded for recording. The ink droplets contain at least a self-dispersible pigment, a water-soluble organic solvent, a surfactant, an organic ultrafine particle internally three-dimensionally crosslinked with an average particle diameter of 0.5 μm or less and water. In addition, the recording is performed on condition that the build-up amount of the ink liquid droplets per unit area of the material on which an image is recorded be within the range of 5 to 40 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００５８】
これらのポリマーラテックスは単独で用いてもよいし、必要に応じて２種以上を併用しても良い。
乳化重合法を用いて合成されたポリマーラテックスは、通常の溶液重合などと比べて、連鎖移動剤等を用いない限り、その分子量は高く、通常１０万以上の質量平均分子量を有する。また、共役ジエンモノマーを用いた場合や２個以上のエチレン性不飽和基を有するモノマーを用いた場合、架橋反応により実質的に無限大の分子量となる場合もある。
【００５９】
ポリマーラテックスを合成するために用いられる乳化重合法について以下に説明する。乳化重合法は、少なくとも１種の乳化剤を用いて、水あるいは水と水に混和しうる有機溶媒（例えばメタノール、エタノール、アセトン等）の混合溶媒中で、分散媒に対して５ないし１５０質量％程度のモノマーを、モノマーに対して０．１ないし２０質量％の乳化剤を用いて乳化させ、モノマーに対して０．０２ないし５質量％のラジカル重合開始剤を用いて、一般に３０℃ないし約１００℃、好ましくは４０℃ないし９０℃の温度で、攪拌下行なわれる。水に混和し得る有機溶媒の量は水に対して体積比で０〜１００％、好ましくは０〜５０％である。
【００６０】
重合開始剤としては、アゾビス化合物、パーオキサイド、ハイドロパーオキサイド、レドックス触媒などがあり、例えば過硫酸カリウム、過硫酸アンモニウム等の無機過酸化物、ｔ−ブチルパーオクトエート、ベンゾイルパーオキサイド、イソプロピルパーカーボネート、２，４−ジクロロベンゾイルパーオキサイド、メチルエチルケトンパーオキサイド、クメンハイドロパーオキサイド、ジクミルパーオキサイド等の有機過酸化物、２，２'−アゾビスイソブチレート、２，２'− アゾビスシアノ吉草酸のナトリウム塩、２，２'−アゾビス（２−アミジノプロパン）ハイドロクロライド、２，２’−アゾビス〔２−（５−メチル−２−イミダゾリン−２−イル）プロパン〕塩酸塩、２，２’−アゾビス｛２−メチル−Ｎ−〔１，１’−ビス（ヒドロキシメチル）−２−ヒドロキシエチル〕プロピオンアミド｝等のアゾ化合物が挙げられる。この中でも過硫酸カリウム、過硫酸アンモニウムが特に好ましい。
【００６１】
乳化剤としてはアニオン性、カチオン性、両性、ノニオン性の界面活性剤の他、水溶性ポリマー等がある。その具体例としては、例えばラウリン酸ソーダ、ドデシル硫酸ナトリウム、１−オクトキシカルボニルメチル−１−オクトキシカルボニルメタンスルホン酸ナトリウム、ラウリルナフタレンスルホン酸ナトリウム、ラウリルベンゼンスルホン酸ナトリウム、ラウリルリン酸ナトリウム、セチルトリメチルアンモニウムクロライド、Ｎ−２−エチルピリジニウムクロライド、ポリオキシエチレンノニルフェニルエーテル、ポリオキシエチレンソルビタンラウリルエステル、ポリビニルアルコール、特公昭５３−６１９０号公報に記載の乳化剤、水溶性ポリマー等が挙げられる。
【００６２】
乳化重合においては、その目的に応じて、重合開始剤、濃度、重合温度、反応時間などを幅広く、かつ容易に変更できることは言うまでもない。また、乳化重合反応は、モノマー、界面活性剤、水性媒体を予め反応容器に全量入れておき、開始剤を投入して行なっても良いし、必要に応じてモノマー、開始剤溶液のいずれか、もしくはその両者の一部あるいは全量を滴下しながら行なっても良い。本発明に用いることのできるラテックスは通常の乳化重合法の手法を用いることにより、容易に合成可能である。一般的な乳化重合の方法については以下の成書に詳しい。「合成樹脂エマルジョン（奥田平、稲垣寛編集、高分子刊行会発行(1978)）」、「合成ラテックスの応用（杉村孝明、片岡靖男、鈴木聡一、笠原啓司編集、高分子刊行会発行(1993)）」、「合成ラテックスの化学（室井宗一著、高分子刊行会発行(1970)）」。また、特にソープフリーラテックスとして知られているものも好ましく用いることができる。
【００６３】
本発明に用いることのできる有機超微粒子の他の例として、水不溶性の解離基含有ポリマーが挙げられる。水不溶性の解離基含有ポリマーとは、イオン性の解離基を有するポリマーを言う。前記イオン性の解離基には、三級アミノ基、四級アンモニウム基等のカチオン性解離基、およびカルボン酸、スルホン酸、リン酸等のアニオン性の解離基が含まれる。前記解離基含有ポリマーとしては、例えばビニルポリマー、縮合系ポリマー（ポリウレタン、ポリエステル、ポリアミド、ポリウレア、ポリカーボネート）が挙げられる。前記水不溶性の解離基含有ポリマーは、水分散性すなわち自己乳化性を有するポリマーであることが好ましい。
【００６４】
解離基含有ビニルポリマーが含有する解離基としては、カルボキシル基、スルホン酸基、硫酸モノエステル基、−ＯＰＯ(ＯＨ)_２、スルフィン酸基、またはこれらの塩（例えば、Ｎａ、Ｋ等のアルカリ金属塩、あるいはアンモニア、ジメチルアミン、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、トリメチルアミン等のアンモニウム塩）のようなアニオン性基、あるいは一級、二級、三級アミン、またはこれらの塩（例えば有機酸（例えば、酢酸、プロピオン酸、メタンスルホン酸）や無機酸（塩酸、硫酸など）の塩）、四級アンモニウム塩の如きカチオン性基が挙げられるが、中でもアニオン性基が好ましく、特にカルボキシル基が好ましい。
【００６５】
前記カルボン酸を解離基として含有するモノマーとしては、例えば、アクリル酸、メタクリル酸、イタコン酸、マレイン酸、フマル酸、シトラコン酸、クロトン酸、イタコン酸モノアルキルエステル（例えば、イタコン酸モノメチル、イタコン酸モノエチル、イタコン酸モノブチルなど）、マレイン酸モノアルキルエステル（例えば、マレイン酸モノメチル、マレイン酸モノエチル、マレイン酸モノブチルなど）などが挙げられる。
【００６６】
前記スルホン酸を解離基として含有するモノマーとしては、例えば、スチレンスルホン酸、ビニルスルホン酸、アクリロイルオキシアルキルスルホン酸（例えば、アクリロイルオキシエチルスルホン酸、アクリロイルオキシプロピルスルホン酸など）、メタクリロイルオキシアルキルスルホン酸（例えば、メタクリロイルオキシエチルスルホン酸、メタクリロイルオキシプロピルスルホン酸など）、アクリルアミドアルキルスルホン酸（例えば、２−アクリルアミド−２−メチルエタンスルホン酸、２−アクリルアミド−２−メチルプロパンスルホン酸、２−アクリルアミド−２−メチルブタンスルホン酸など）、メタクリルアミドアルキルスルホン酸（例えば、２−メタクリルアミド−２−メチルエタンスルホン酸、２−メタクリルアミド−２−メチルプロパンスルホン酸など）などが挙げられる。
【００６７】
前記リン酸を解離基として含有するモノマーとしては、例えば、リン酸モノアクリロイルオキシエチルエステル、リン酸モノメタクリロイルオキシエチルエステルなどが挙げられる。
これらの中でも、アクリル酸、メタクリル酸、スチレンスルホン酸、ビニルスルホン酸、アクリルアミドアルキルスルホン酸、メタクリルアミドアルキルスルホン酸が好ましく、アクリル酸、メタクリル酸、スチレンスルホン酸、２−アクリルアミド−２−メチルプロパンスルホン酸、２−アクリルアミド−２−メチルブタンスルホン酸が特に好ましい。
【００６８】
前記カチオン性の解離基を有するモノマーとしては、例えば、ジアルキルアミノエチルメタクリレート、ジアルキルアミノエチルアタクリレートなどの３級アミノ基を有するモノマーや、Ｎ−２−アクリロイルオキシエチル−Ｎ，Ｎ，Ｎ−トリメチルアンモニウムクロライド、Ｎ−ビニルベンジル−Ｎ，Ｎ，Ｎ−トリエチルアンモニウムクロライドなどの４級アンモニウム基を有するモノマーが挙げられる。
【００６９】
また、上記の解離基含有モノマーは、解離基を有しないモノマーと共重合させてもよく、それに用いられるモノマーとしては以下のものを挙げることができる。すなわち、アクリル酸エステル類、具体的には、メチルアクリレート、エチルアクリレート、ｎ−プロピルアクリレート、イソプロピルアクリレート、ｎ−ブチルアクリレート、イソブチルアクリレート、ｓｅｃ−ブチルアクリレート、ｔｅｒｔ−ブチルアクリレート、ヘキシルアクリレート、２−エチルヘキシルアクリレート、ｔｅｒｔ−オクチルアクリレート、２−クロロエチルアクリレート、２−ブロモエチルアクリレート、４−クロロブチルアクリレート、２−アセトキシエチルアクリレート、ベンジルアクリレート、シクロヘキシルアクリレート、フルフリルアクリレート、テトラヒドロフルフリルアクリレート、フェニルアクリレート、２−ヒドロキシエチルアクリレート、２，２−ジメチル−３−ヒドロキシプロピルアクリレート、２−メトキシエチルアクリレート、３−メトキシブチルアクリレート、２−エトキシエチルアクリレート、２−ブトキシエチルアクリレート、２−（２−メトキシエトキシ）エチルアクリレート、グリシジルアクリレート、１−ブロモ−２−メトキシエチルアクリレート、２，２，２−テトラフルオロエチルアクリレート、１Ｈ，１Ｈ，２Ｈ，２Ｈ−パーフルオロデシルアクリレート、ジフェニル−２−アクリロイルオキシエチルホスフェート、ジフェニル−２−メタクリロイルオキシエチルホスフェート、ジブチル−２−アクリロイルオキシエチルホスフェート等が挙げられる。
【００７０】
メタクリル酸エステル類、具体的には、メチルメタクリレート、エチルメタクリレート、ｎ−プロピルメタクリレート、イソプロピルメタクリレート、ｎ−ブチルメタクリレート、イソブチルメタクリレート、ｓｅｃ−ブチルメタクリレート、ｔｅｒｔ−ブチルメタクリレート、シクロヘキシルメタクリレート、ベンジルメタクリレート、２−エチルヘキシルメタクリレート、ラウリルメタクリレート、ステアリルメタクリレート、フルフリルメタクリレート、テトラヒドロフルフリルメタクリレート、フェニルメタクリレート、クレジルメタクリレート、ナフチルメタクリレート、２−ヒドロキシエチルメタクリレート、４−ヒドロキシブチルメタクリレート、トリエチレングリコールモノメタクリレート、ジプロピレングリコールモノメタクリレート、２−メトキシエチルメタクリレート、３−メトキシブチルメタクリレート、２−エトキシエチルメタクリレート、２−ブトキシエチルメタクリレート、２−（２−メトキシエトキシ）エチルメタクリレート、２−（２−エトキシエトキシ）エチルメタクリレート、２−アセトキシエチルメタクリレート、２−アセトアセトキシエチルメタクリレート、アリルメタクリレート、グリシジルメタクリレート、２，２，２−テトラフルオロエチルメタクリレート、１Ｈ，１Ｈ，２Ｈ，２Ｈ−パーフルオロデシルメタクリレート、ジオクチル−２−メタクリロイルオキシエチルホスフェートなどが挙げられる。
【００７１】
ビニルエステル類、具体的には、ビニルアセテート、ビニルプロピオネート、ビニルブチレート、ビニルカプロエート、ビニルクロロアセテート、ビニルメトキシアセテート、ビニルフェニルアセテート、安息香酸ビニル、サリチル酸ビニルなどが挙げられる。
【００７２】
アクリルアミド類、具体的には、アクリルアミド、メチルアクリルアミド、エチルアクリルアミド、イソプロピルアクリルアミド、ｎ−ブチルアクリルアミド、ｔｅｒｔ−ブチルアクリルアミド、ｔｅｒｔ−オクチルアクリルアミド、シクロヘキシルアクリルアミド、ベンジルアクリルアミド、ヒドロキシメチルアクリルアミド、メトキシメチルアクリルアミド、ブトキシメチルアクリルアミド、メトキシエチルアクリルアミド、フェニルアクリルアミド、ジメチルアクリルアミド、ジエチルアクリルアミド、β−シアノエチルアクリルアミド、Ｎ−（２−アセトアセトキシエチル）アクリルアミド、ジアセトンアクリルアミドなどが挙げられる。
【００７３】
メタクリルアミド類、具体的には、メタクリルアミド、メチルメタクリルアミド、エチルメタクリルアミド、プロピルメタクリルアミド、ｎ−ブチルメタクリルアミド、ｔｅｒｔ−ブチルメタクリルアミド、シクロヘキシルメタクリルアミド、ベンジルメタクリルアミド、ヒドロキシメチルメタクリルアミド、メトキシエチルメタクリルアミド、フェニルメタクリルアミド、β−シアノエチルメタクリルアミド、Ｎ−（２−アセトアセトキシエチル）メタクリルアミドなどが挙げられる。
【００７４】
オレフィン類、具体的には、ジシクロペンタジエン、エチレン、プロピレン、１−ブテン、１−ペンテン、塩化ビニル、塩化ビニリデン、イソプレン、クロロプレン、ブタジエン、２，３−ジメチルブタジエン等が挙げられる。
【００７５】
スチレン類、例えば、スチレン、メチルスチレン、ジメチルスチレン、トリメチルスチレン、エチルスチレン、クロルメチルスチレン、メトキシスチレン、アセトキシスチレン、クロルスチレン、ジクロルスチレン、ブロムスチレン、ビニル安息香酸メチルエステルなどが挙げられる。
【００７６】
ビニルエーテル類、具体的には、メチルビニルエーテル、ブチルビニルエーテル、ヘキシルビニルエーテル、メトキシエチルビニルエーテルなどが挙げられる。
【００７７】
その他のモノマーとして、クロトン酸ブチル、クロトン酸ヘキシル、イタコン酸ジメチル、イタコン酸ジブチル、マレイン酸ジエチル、マレイン酸ジメチル、マレイン酸ジブチル、フマル酸ジエチル、フマル酸ジメチル、フマル酸ジブチル、メチルビニルケトン、フェニルビニルケトン、メトキシエチルビニルケトン、Ｎ−ビニルオキサゾリドン、Ｎ−ビニルピロリドン、ビニリデンクロライド、メチレンマロンニトリル、ビニリデンなどが挙げられる。
【００７８】
また、以下に挙げるような非イオン性分散性基を含有するモノマーを共重合することも好ましく、このようなモノマーの例としては、ポリエチレングリコールモノアルキルエーテルとカルボン酸モノマーとのエステル、ポリエチレングリコールモノアルキルエーテルとスルホン酸モノマーとのエステル、ポリエチレングリコールモノアルキルエーテルとリン酸モノマーとのエステル、ポリエチレングリコールモノアルキルエーテルとイソシアネート基含有モノマーから形成されるビニル基含有ウレタン、ポリビニルアルコール構造を含有するマクロモノマーなどが挙げられる。前記ポリエチレングリコールモノアルキルエーテルのエチレンオキシ部の繰り返し数としては、８〜５０が好ましく、１０〜３０がより好ましい。前記ポリエチレングリコールモノアルキルエーテルのアルキル基の炭素原子数としては、１〜２０が好ましく、１〜１２がより好ましい。
【００７９】
次に、前記の解離基含有縮合系ポリマーについて詳細に説明する。前記解離基含有ポリウレタンは基本的にジオール化合物とジイソシアネート化合物を原料とした重付加反応により合成される。
ジオール化合物の具体例としては、非解離性のジオールとしてエチレングリコール、１，２−プロパンジオール、１，３−プロパンジオール、１，３-ブタンジオール、２，３−ブタンジオール、２，２−ジメチル−１，３−プロパンジオール、１，４−ペンタンジオール、２，４−ペンタンジオール、３，３−ジメチル−１，２−ブタンジオール、２−エチル−２−メチル−１，３−プロパンジオール、１，６−ヘキサンジオール、２，５−ヘキサンジオール、２−メチル−２，４−ペンタンジオール、２，２−ジエチル−１，３−プロパンジオール、２，４−ジメチル−２，４−ペンタンジオール、２−メチル−２−プロピル−１，３−プロパンジオール、２，５−ジメチル−２，５−ヘキサンジオール、２−エチル−１，３−ヘキサンジオール、１，２−オクタンジオール、２，２，４−トリメチル−１，３−ペンタンジオール、１，４−シクロヘキサンジメタノール、ジエチレングリコール、トリエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、ポリエチレングリコール（平均分子量＝２００〜４０００）、ポリプロピレングリコール（平均分子量＝２００〜１０００）、ポリエステルポリオール、４，４’−ジヒドロキシジフェニル−２，２−プロパン、４，４’−ジヒドロキシフェニルスルホン等を挙げることができる。
【００８０】
ジイソシアネートの好ましい具体例としては、エチレンジイソシアネート、イソホロンジイソシアネート、ヘキサメチレンジイソシアネート，１，４−シクロヘキサンジイソシアネート、２，４−トルエンジイソシアネート、１，３−キシリレンジイソシアネート、１，５−ナフタレンジイソシアネート，ｍ−フェニレンジイソシアネート、ｐ−フェニレンジイソシアネート、３，３'-ジメチルー４，４’−ジフェニルメタンジイソシアネート、３，３’−ジメチルビフェニレンジイソシアネート、ジシクロヘキシルメタンジイソシアネート、メチレンビス(４−シクロヘキシルイソシアネート)等を挙げることができる。
【００８１】
解離性基含有ポリウレタンは、例えばポリウレタンの合成時に解離基を含有するジオールを使用することによって得られる。その場合は、解離基はポリマー主鎖からの置換基としてポリウレタンに導入される。解離基、特にアニオン性基を有するジオールとしては、２，２−ビス(ヒドロキシメチル)プロピオン酸、２，２−ビス(ヒドロキシメチル)ブタン酸、２，５，６−トリメトキシ−３，４−ジヒドロキシヘキサン酸、２，３−ジヒドロキシ−４，５−ジメトキシペンタン酸、３，５−ジ（２−ヒドロキシ）エチルオキシカルボニルベンゼンスルホン酸及びこれらの塩を挙げることができるが、特にこれらに限定されるものではない。
【００８２】
解離基含有ポリウレタンが含有する解離基としては、カルボキシル基、スルホン酸基、硫酸モノエステル基、−ＯＰＯ(ＯＨ)_２、スルフィン酸基、またはこれらの塩（例えば、Ｎａ、Ｋ等のアルカリ金属塩、あるいはアンモニア、ジメチルアミン、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、トリメチルアミン等のアンモニウム塩）のようなアニオン性基、あるいは一級、二級、三級アミン、四級アンモニウム塩の如きカチオン性基が挙げられ、中でもアニオン性基が好ましく、特にカルボキシル基が好ましい。
【００８３】
前記ポリエステルは、基本的にジオール化合物とジカルボン酸化合物の縮合反応によって合成される。ジカルボン酸化合物の具体的な例としては、シュウ酸、マロン酸、コハク酸、グルタル酸、ジメチルマロン酸、アジピン酸、ピメリン酸、α，α―ジメチルコハク酸、アセトンジカルボン酸、セバシン酸、１，９−ノナンジカルボン酸、フマル酸、マレイン酸、イタコン酸、シトラコン酸、フタル酸、イソフタル酸、テレフタル酸、２−ブチルテレフタル酸、テトラクロロテレフタル酸、アセチレンジカルボン酸、ポリ（エチレンテレフタレート）ジカルボン酸、１，２−シクロヘキサンジカルボン酸、１，４−シクロヘキサンジカルボン酸、ω―ポリ（エチレンオキシド）ジカルボン酸、ｐ−キシリレンジカルボン酸などを挙げることができる。これらの化合物は、ジオール化合物と重縮合反応を行なう際に、ジカルボン酸のアルキルエステル（例えば、ジメチルエステル）やジカルボン酸の酸塩化物の形で用いても良いし、無水マレイン酸や無水コハク酸、無水フタル酸のように酸無水物の形で用いても良い。
【００８４】
解離基含有ポリエステルは、カルボン酸以外に、スルホン酸基、硫酸モノエステル基、−ＯＰＯ(ＯＨ)_２、スルフィン酸基、またはこれらの塩（例えば、Ｎａ、Ｋ等のアルカリ金属塩、あるいはアンモニア、ジメチルアミン、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、トリメチルアミン等のアンモニウム塩）のようなアニオン性基、あるいは三級アミンまたはこれらの塩（例えば、有機酸（例えば、酢酸、プロピオン酸、メタンスルホン酸）や無機酸（塩酸、硫酸など）の塩）、四級アンモニウム塩の如きカチオン性基のような解離基を有するジカルボン酸化合物を用いて合成することにより得られる。解離基含有ポリエステルが含有するカルボン酸以外の解離基としては、アニオン性基が好ましく、特にスルホン酸基が好ましい。
【００８５】
前記スルホン酸基を有するジカルボン酸、ジオール原料の好ましい例としては、スルホフタル酸類（３−スルホフタル酸、４−スルホフタル酸、４−スルホイソフタル酸、５−スルホイソフタル酸、２−スルホテレフタル酸）、スルホコハク酸、スルホナフタレンジカルボン酸類(４−スルホ−１，８−ナフタレンジカルボン酸、７−スルホ−１，５−ナフタレンジカルボン酸等)、３，５−ジ（２−ヒドロキシ）エチルオキシカルボニルベンゼンスルホン酸及びこれらの塩を挙げることができる。
【００８６】
ジオール化合物としては、上記ポリウレタンにおいて記載したジオール類と同じ群から選ばれる化合物を用いることができる。前記ポリエステルの代表的な合成法は上記のジオール化合物とジカルボン酸もしくはその誘導体の縮合反応であるが、ヒドロキシカルボン酸（例えば、１２−ヒドロキシステアリン酸）のようなヒドロキシカルボン酸を縮合して得ることもできるし、環状エーテルとラクトン類の開環重合法（講座重合反応論６ 開環重合（Ｉ）三枝武夫著(化学同人、１９７１年)に詳しい）等の方法で得られるポリエステルも本発明に好適に用いることができる。
【００８７】
前記ポリアミドは、ジアミン化合物とジカルボン酸化合物の重縮合、アミノカルボン酸化合物の重縮合もしくはラクタム類の開環重合等によって得ることができる。ジアミン化合物としては、エチレンジアミン、１，３−プロパンジアミン、１，２−プロパンジアミン、ヘキサメチレンジアミン、オクタメチレンジアミン、ｏ−フェニレンジアミン、ｍ−フェニレンジアミン、ｐ−フェニレンジアミン、ピペラジン、２，５−ジメチルピペラジン、４，４’−ジアミノジフェニルエーテル、３，３’−ジアミノジフェニルスルホン、キシリレンジアミン等を挙げることができ、アミノカルボン酸としてはグリシン、アラニン、フェニルアラニン、ω−アミノヘキサン酸、ω−アミノデカン酸、ω−アミノウンデカン酸、アントラニル酸が挙げられる。また、開環重合に用い得る単量体としてはε−カプロラクタム、アゼチジノン、ピロリドン等を挙げることができる。ジカルボン酸化合物としては、上記ポリエステルにおいて説明したジカルボン酸類と同じ群から選ばれる化合物を用いることができる。
【００８８】
前記ポリウレアは、基本的にジアミン化合物とジイソシアネート化合物の重付加もしくはジアミン化合物と尿素の脱アンモニア反応によって得ることができ、原料であるジアミン化合物は上記ポリアミドにおいて記載したジアミン類、ジイソシアネート化合物は上記ポリウレタンにおいて記載したジイソシアネート類と同じ群から選ばれる化合物を用いることができる。
【００８９】
前記ポリカーボネートは、基本的にジオール化合物とホスゲンもしくは炭酸エステル誘導体（例えば、ジフェニルカーボネート等の芳香族エステル）を反応させることにより得ることができ、原料であるジオール化合物は上記ポリウレタンにおいて記載したジオール類と同じ群からなる化合物を用いることができる。
【００９０】
前記解離基は、種々の方法で前記各ポリマーに導入することができる。例えばポリウレタンの場合、前記したように、解離基を含有するジオールを合成時に用いて、ポリマー主鎖からの置換基として導入することができる。また、前記水不溶性ポリマーとしてポリエステルを使用する場合のように、ポリマーの末端にジカルボン酸の未反応末端として残存させることによって導入することもできる。さらに、前記各ポリマーの重合後に、ヒドロキシ基、アミノ基等の反応性基に対し、酸無水物（例えば無水マレイン酸）等の反応によって解離基を導入できる化合物を作用させて導入することもできる。
【００９１】
以上述べてきた解離基含有ポリマーは、ビニルポリマー、縮合ポリマーともに、必要な構成原料を１種ずつ用いても良いし、種々の目的（例えば、ポリマーのガラス転移温度（Ｔｇ）の調整や溶解性、染料との相溶性、分散物の安定性）に応じて、それぞれ２種以上を任意の割合で用いることができる。
【００９２】
また、前記解離基含有ポリマーの中でも、前記解離性基としてカルボキシル基及びスルホン酸基の少なくとも一方を有するものが好ましく、前記解離性基としてカルボキシル基を有するものが特に好ましい。
前記解離性基の含量が、少なすぎても多すぎても解離基含有ポリマーの自己乳化性が小さく、染料の微粒子分散物の安定化効果が小さくなる傾向があるので、前記解離基含有ポリマーにおける解離性基の含量として好ましい範囲は、０．１〜３．０ｍｍｏｌ／ｇであり、０．２〜２．０ｍｍｏｌ／ｇの範囲がより好ましい。
【００９３】
なお、前記解離基として、前記アニオン性の解離基としては、更に、アルカリ金属（例えばＮａ、Ｋなど）又はアンモニウムイオンの塩などであってもよく、前記カチオン性の解離基である３級アミンでは、更に、有機酸（例えば、酢酸、プロピオン酸、メタンスルホン酸）や無機酸（塩酸、硫酸など）の塩であってもよい。
【００９４】
前記解離基含有ポリマーにおいて、優れた分散安定性付与、解離基導入の容易さ等を勘案すると、より好ましいのはビニルポリマー、ポリウレタン、ポリエステルであり、特に好ましいのはビニルポリマーである。
【００９５】
前記解離基含有ビニルポリマーの具体例（ＰＰ−１）〜（ＰＰ−５４）を表２および表３に列挙するが、本発明は、これらの具体例に何ら限定されるものではない。なお、括弧内の比は質量比を意味する。
【００９６】
【表２】

【００９７】
【表３】

【００９８】
また、前記解離基含有ポリマーのうち、縮合系ポリマーの具体例（ＰＰ−５５）〜（ＰＰ−７４））を表４に挙げるが、本発明がこれらに限定されるものではない。各ポリマーにおける酸性基はすべて非解離形で表わしてある。またポリエステル、ポリアミド等縮合反応により生成するものについては、構成成分は原料の如何に関わらずすべてジカルボン酸、ジオール、ジアミン、ヒドロキシカルボン酸、アミノカルボン酸等で表記する。括弧内の比は、各成分のモル百分率比を意味する。
【００９９】
【表４】

【０１００】
上記の解離基含有縮合系ポリマーの合成に関しては、「高分子実験学(第５巻)重縮合と重付加（神原周編集、共立出版(株)発行(1980)）」、「ポリエステル樹脂ハンドブック（滝山栄一郎著、日刊工業新聞社発行(1988)）」、「ポリウレタン樹脂ハンドブック（岩田敬治編、日刊工業新聞社発行(1987)）」、「高分子合成の実験法（大津隆行・木下雅悦共著、化学同人発行(1972)）」、特公昭３３−１１４１号公報、特公昭３７−７６４１号公報、特公昭３９−５９８９号公報、特公昭４０−２７３４９号公報、特公昭４２−５１１８号公報、特公昭４２−２４１９４号公報、特公昭４５−１０９５７号公報、特公昭４８−２５４３５号公報、特公昭４９−３６９４２号公報、特公昭５２−８１３４４号公報、特開昭５６−８８４５４号公報、特開平６−３４０８３５号公報などの各公報に記載されている公知の方法を用いることができる。
【０１０１】
（有機超微粒子の合成方法）
＜有機超微粒子［１］の合成例＞
有機超微粒子はコア層とシェル層の屈折率の差が０．１７となるようにコア層とシェル層のモノマーを選択して製造する。以下にその方法を示す。
攪拌機、温度計、還流冷却器、滴下漏斗を付けた１Ｌのフラスコに、蒸留水４００ｍｌ、過硫酸カリウム０．１５ｇ、Ｅｍｕｌｇｅｎ９１３（Ｋａｏ−Ａｔｌａｓ社製）１．６ｇを仕込んで攪拌し、予め混合しておいたスチレン５０ｇ、ｎ−ドデシルメルカプタン０．１ｇ、ＬｅｖｅｎｏｌＷＺ（Ｋａｏ−Ａｔｌａｓ社製）０．４ｇを加えて、窒素置換しながら７５℃まで加熱する。その後、７５℃で１時間重合する。次いで、予め混合しておいたメタクリル酸トリデシル４５ｇ、メタクリル酸５ｇ及びｎ−ドデシルメルカプタン０．１ｇを、過硫酸カリウム０．１５ｇを溶解した蒸留水１５ｇに混合した混合液を１．５時間かけて一定速度で滴下する。その後、７５℃で５時間保持する。得られた乳濁液を常温まで冷却し、中和剤としてアンモニア水を添加してｐＨを調整する。更に、０．４μｍのフィルターで濾過し、ポリマー微粒子の濃度が３０％となるように蒸留水で調製する。得られた有機超微粒子のガラス転移点は１２℃である。又、得られた有機超微粒子を分散粒子とするポリマーエマルジョンの最低成膜温度が２０℃近辺である。
【０１０２】
＜有機超微粒子［２］の合成例＞
表５に示す原料を、表５に示す割合で、予めＮ_２ガスで飽和された反応釜および滴下槽に仕込んだ。重合反応は５５〜５７℃で開始し、反応釜の温度が５９℃となったとき、滴下を開始した。滴下時間は１００分とした。重合は、６０〜６５℃の温度範囲内で行ない、約３時間で反応は終結した。その後、２５％アンモニア水でｐＨ８〜９に調整し、固形分２０％の水分散型樹脂組成物を得た。得られた水分散型樹脂組成物の平均粒径は、レーザー光散乱法による測定値で１２０ｎｍであった。
【０１０３】
【表５】

【０１０４】
＜有機超微粒子［３］、［４］の合成例＞
表６に示す原料を用い、合成例［２］と同様にして固形分２０％の水分散型樹脂組成物を得た。重合進行性、得られた水分散型樹脂組成物中の凝集物の有無および平均粒径を表６に示す。
【０１０５】
【表６】

【０１０６】
＜有機超微粒子［５］〜［８］の合成例＞
［５］＝Ａ１
［６］＝Ａ２
［７］＝Ａ３
［８］＝Ａ４
《ポリエステル樹脂の重合》
温度計、攪拌機を備えたオートクレーブ中に、
シクロヘキサンジカルボン酸 １５６．４重量部
エチレングリコ−ル １１１．６重量部
トリシクロデカンジメタノール ７８．４重量部
テトラブトキシチタネート ０．１重量部
を仕込み、１５０〜２２０℃で１８０分間加熱してエステル化反応を行なった。次いで、２４０℃に昇温した後、系の圧力を徐々に減じて３０分後に１０ｍｍＨｇとし、１２０分間反応を続けた。その後オ−トクレ−ブ中を窒素ガスで置換し、大気圧とした。
温度を２００〜２２０℃に保ち、無水トリメリット酸１５．４重量部を加え、６０分間反応を行ない、共重合ポリエステル樹脂（Ａ１）を得た。得られた共重合ポリエステル樹脂は平均分子量は３３００、酸価３６０ｅｑ．／ｔｏｎ、ガラス転移温度は７０℃であった。またＮＭＲ分析によりその組成比は表７に示す如きであった。
【０１０７】
【表７】

【０１０８】
以下同様に原料を代えて重合を行ない、表７に示すポリエステル樹脂を得た。
なお、表７中、
ＣＨＤＡ：シクロヘキサンジカルボン酸
ＴＰＡ：テレフタル酸
ＩＰＡ：イソフタル酸
ＳＩＰ：５−ナトリウムスルホイソフタル酸
ＴＭＡ：トリメリット酸
ＥＧ：エチレングリコール
ＮＰＧ：ネオペンチルグリコール
ＴＣＤＬ：トリシクロデカンジメタノール
Ｔｇ：ガラス転移温度
である。
ポリエステル樹脂（Ａ４）では、加えて蛍光Ｘ線分析により硫黄元素の含有量を求めスルホン酸ナトリウム基当量に換算した。
【０１０９】
本発明の記録液には、有機超微粒子以外にも樹脂エマルジョンが添加されているのが好ましい。樹脂エマルジョンとは、連続相が水であり、分散相が次の様な樹脂成分であるエマルジョンを意味する。分散相の樹脂成分としてはアクリル系樹脂、酢酸ビニル系樹脂、スチレン−ブタジエン系樹脂、塩化ビニル系樹脂、アクリル−スチレン系樹脂、ブタジエン系樹脂、スチレン系樹脂などが挙げられる。
【０１１０】
本発明の好ましい態様によれば、この樹脂は親水性部分と疎水性部分とを併せ持つ重合体であるのが好ましい。また、これらの樹脂成分の粒子径はエマルジョンを形成する限り特に限定されないが、１５０ｎｍ程度以下が好ましく、より好ましくは５〜１００ｎｍ程度である。
これらの樹脂エマルジョンは、樹脂粒子を、場合によって界面活性剤とともに水に混合することによって得ることができる。
例えば、アクリル系樹脂またはスチレン−アクリル系樹脂のエマルジョンは、（メタ）アクリル酸エステルまたはスチレンと、(メタ)アクリル酸エステルと、場合により（メタ）アクリル酸エステルと、界面活性剤とを水に混合することによって得ることができる。樹脂成分と界面活性剤との混合の割合は、通常１０：１〜５：１程度とするのが好ましい。界面活性剤の使用量が前記範囲に満たない場合、エマルジョンとなりにくく、また前記範囲を超える場合、インクの耐水性が低下したり、浸透性が悪化する傾向があるので好ましくない。
前記エマルジョンの分散相成分としての樹脂と水との割合は、樹脂１００重量部に対して水６０〜４００重量部、好ましくは１００〜２００の範囲が適当である。
【０１１１】
市販の樹脂エマルジョンとしては、マイクロジェルＥ−１００２、Ｅ−５００２（スチレン−アクリル系樹脂エマルジョン、日本ペイント株式会社製）、ボンコート４００１（アクリル系樹脂エマルジョン、大日本インキ化学工業株式会社製）、ボンコート５４５４（スチレン−アクリル系樹脂エマルジョン、大日本インキ化学工業株式会社製）、ＳＡＥ−１０１４（スチレン−アクリル系樹脂エマルジョン、日本ゼオン株式会社製）、サイビノールＳＫ−２００（アクリル系樹脂エマルジョン、サイデン化学株式会社製）、などが挙げられる。
本発明に使用するインクは、樹脂エマルジョンを、その樹脂成分がインクの０．１〜４０重量％となるよう含有するのが好ましく、より好ましくは１〜２５重量％の範囲である。
樹脂エマルジョンは、増粘・凝集する性質を持ち、着色成分の浸透を抑制し、さらに記録材への定着を促進する効果を有する。また、樹脂エマルジョンの種類によっては記録材上で皮膜を形成し、印刷物の耐擦性をも向上させる効果を有する。
【０１１２】
（６）防腐剤、（７）ｐＨ調整剤、（８）緩衝剤、（９）消泡剤、（１０）純水
本発明のインクには上記着色剤、溶媒、界面活性剤の他に従来より知られている添加剤を加えることができる。
例えば、防腐防黴剤としてはデヒドロ酢酸ナトリウム、ソルビン酸ナトリウム、２−ピリジンチオール−１−オキサイドナトリウム、安息香酸ナトリウム、ペンタクロロフェノールナトリウム等が本発明に使用できる。
ｐＨ調整剤としては、調合されるインクに悪影響をおよぼさずにｐＨを７以上に調整できるものであれば、任意の物質を使用することができる。
その例として、ジエタノールアミン、トリエタノールアミン等のアミン、水酸化リチウム、水酸化ナトリウム、水酸化カリウム等のアルカリ金属元素の水酸化物、水酸化アンモニウム、第４級アンモニウム水酸化物、第４級ホスホニウム水酸化物、炭酸リチウム、炭酸ナトリウム、炭酸カリウム等のアルカリ金属の炭酸塩等が挙げられる。
キレート試薬としては、例えば、エチレンジアミン四酢酸ナトリウム、ニトリロ三酢酸ナトリウム、ヒドロキシエチルエチレンジアミン三酢酸ナトリウム、ジエチレントリアミン五酢酸ナトリウム、ウラミル二酢酸ナトリウム等がある。
防錆剤としては、例えば、酸性亜硫酸塩、チオ硫酸ナトリウム、チオジグリコール酸アンモン、ジイソプロピルアンモニウムニトライト、四硝酸ペンタエリスリトール、ジシクロヘキシルアンモニウムニトライト等がある。
その目的に応じて緩衝剤、消泡剤、水溶性紫外線吸収剤、水溶性赤外線吸収剤等を添加することができる。
【０１１３】
２．インクジェット印字装置
図４は本発明の構成の印字装置の側面説明図である。このインクジェット印字装置は、印字装置本体（１）の内部に固定された印字ヘッド、印字ヘッドへインクを供給するインクカートリッジ等で構成される印字機構部（２）等を収納し、装置本体（１）の下方部側には前方側より多数枚の用紙（３）を積載可能な給紙カセット（或いは給紙トレイでもよい。）（４）を抜き差し自在に装着することができ、また、用紙（３）を手差しで給紙するための手差しトレイを開倒することができ、給紙カセット（４）或いは手差しトレイから給送される用紙（３）を取り込んで、印字機構部（２）によって所要の画像を印字した後、後面側に装着された排紙トレイ（６）から排紙される。
【０１１４】
印字機構部（２）は、イエロー（Ｙ）、シアン（Ｃ）、マゼンタ（Ｍ）、ブラック（Ｂｋ）の各色のインク液滴を吐出するインクジェットヘッドからなるライン状のヘッド（１４）がこの順序で具備され、インク液滴の吐出方向を下方に向けて装着される。また、ヘッド（１４）に各色のインクを供給するための各インクカートリッジ（１５）を交換可能にして装着されている。
インクカートリッジ（１５）は上方に大気と連通する大気口、下方にはインクジェットヘッドへインクを供給する供給口を、内部にはインクが充填された多孔質体を有しており、多孔質体の毛管力によりインクジェットヘッドへ供給されるインクを僅かながら負圧して維持している。
【０１１５】
また、本例では、印字ヘッドとして各色個別構成のヘッド（１４）を用いて構成しているが、各色のインク液滴を吐出するノズル列を有する１個のヘッド構成としてもよい。さらに、インクを加圧してインク液滴を形成せしめる印字ヘッド（インクジェットヘッド）（１４）としては、ピエゾ素子などの電気機械変換素子で液室壁面を形成し、振動板を介してインク加圧する圧電型、或いは発熱抵抗体によりインク中に気泡を生じさせてインク加圧するバブル型、若しくはインク流路壁面を形成する振動板とこれに対向する電極との間の静電気力で振動板を変位させてインク加圧する静電型などを使用することができるが、本構成例では圧電型インクジェットヘッドを利用した場合について説明する。
【０１１６】
給紙カセット（４）にセットした用紙（３）をヘッド（１４）の下方側に搬送するために、給紙カセット（４）からは、用紙（３）を分離給装する給紙ローラ（２１）及びフリクションパッド（２２）と、用紙（３）を案内するガイド部材（２３）と、給紙された用紙（３）を反転させて搬送する搬送ローラ（２４）と、この搬送ローラ（２４）の周面に押し付けられる搬送コロ（２５）及び搬送ローラ（２４）からの用紙（３）の送り出し角度を規定する先端コロ（２６）とを設けている。搬送ローラ（２４）は副走査モータ（２７）によってギヤ列を介して回転駆動される。そして、キャリッジ（１３）の主走査方向の移動範囲に対応して搬送ローラ（２４）から送り出された用紙（３）を印字ヘッド（１４）の下方側まで案内（ガイド）するために、用紙ガイド部材である印写受け部材を設置している。更に、印写受け部材の用紙搬送方向下流側には、用紙（３）を排紙方向へ送り出すために回転駆動される搬送コロ（３１）、及び拍車（３２）とを設け、さらに用紙（３）を排紙トレイ（６）に送り出すための排紙ローラ（３３）、及び拍車（３４）と、排紙経路を確保するためのガイド部材（３５）、（３６）等を配設している。
【０１１７】
また、キャリッジ（１３）の移動方向右端側の印字領域を外れた位置には、ヘッド（１４）の吐出不良を回復するための回復処理装置を配置している。回復処理装置にはキャップ手段と吸引手段とクリーニング手段とを有している。キャリッジ（１３）は印字待機中にはこの回復処理装置側に移動されてキャッピング手段でヘッド（１４）がキャッピングされ、吐出口部を湿潤状態に保つことによりインク乾燥によるインク吐出不良を防ぐことができる。また、印字途中などに印字と関係しないインクを吐出することで、全ての吐出口内のインク粘度が一定となり、安定した吐出性能が維持される。吐出不良が発生した場合等には、キャッピング手段でヘッド（１４）の吐出口を密封し、チューブを通して吸引手段で吐出口からインクとともに気泡等を吸い出し、吐出口面に付着したインクやゴミ等はクリーニング手段により除去され吐出不良が回復される。また、吸引されたインクは、本体下部に設置された廃インク溜（不図示）に排出され、廃インク溜内部のインク吸収体に吸収保持される。
【０１１８】
【実施例】
以下、実施例により、本発明を具体的に説明するが、本発明は、これらに限定されるものではない。なお、実施例に記載の各成分の量（％）は重量基準である。
顔料の表面処理（自己分散性顔料の作製方法）
黒としてはカーボンブラックとして、ファーネス法、チャネル法で製造されたカーボンブラックで、１次粒子が１５ｎｍ〜４０ｎｍ、ＢＥＴ吸着法による比表面積が５０〜３００ｍ^２／ｇ、ＤＢＰ吸油量が４０〜１５０ｍｌ／１００ｇ、揮発分が０．５〜１０％、ｐＨ２〜９を有するものが使用され、特にｐＨ６以下の酸性カーボンブラックが高濃度で好ましい。また、次亜塩素酸化処理したカーボンブラックやスルホン化剤処理したカーボンブラック、ジアゾニュウム化合物にて処理してスルホン酸、カルボン酸等のアニオン性解離基を導入したカーボンブラックがさらに好ましい。イエロー顔料としてはベンチジン骨格を含まないＣ．Ｉピグメントイエロー７４、１２８、１３８が好ましい。マゼンタ顔料としてはキナクリドン系のＣ．Ｉ．ピグメントレッド１２２、２０９が好ましい。シアンはフタロシアニン化合物であるＣ．Ｉ．ピグメントブルー１５：３やアルミ配位フタロシアニン、無金属フタロシアニンが好ましい。これらカラー有機顔料も表面処理によりスルホン酸基、カルボン酸基が導入された顔料はさらに分散安定性が優れ、分散剤なしに分散安定性が得られるものは自己分散顔料として好適に用いることができる。また、表面をカプセル化した顔料やポリマーをグラフトした顔料等も分散安定性に優れ信頼性の高いインクとすることができる。
【０１１９】
（参考例１）次亜塩素酸処理したカーボンブラック１
市販のｐＨ２．５の酸性カーボンブラック（キャボット社製 商品名モナーク１３００）３００ｇを水１０００ミリリットルに良く混合した後に次亜塩素酸ソーダ（有効塩素濃度１２％）４５０ｇを滴下して、１００〜１０５℃で８時間撹拌した。この液に更に次亜塩素酸ソーダ（有効塩素濃度１２％）１００ｇを加え、横型分散機で３時間分散した。得られたスラリーを水で１０倍に希釈し、水酸化リチウムにてｐＨを調整し、電導度０．２ｍＳ／ｃｍまで限外濾過膜にて脱塩濃縮し顔料濃度１５％のカーボンブラック分散液とした。遠心処理により粗大粒子を除き、さらに１ミクロンのナイロンフィルターで濾過しカーボンブラック分散液１とした。マイクロトラックＵＰＡで測定した平均粒子径（Ｄ５０％）は９５ｎｍであった。
【０１２０】
（参考例２）スルホン化剤処理したカーボンブラック２
市販のカーボンブラック顔料（デグサ社製「プリンテックス＃８５」）１５０ｇをスルホラン４００ｍｌ中に良く混合し、ビーズミルで微分散後、アミド硫酸１５ｇを添加して１４０〜１５０℃で１０時間攪拌した。得られたスラリーをイオン交換水１０００ｍｌ中に投入し、１２０００ｒｐｍで遠心分離機により表面処理カーボンブラックウエットケーキを得る。このカーボンブラックウエットケーキを２０００ｍｌのイオン交換水中に再分散し、水酸化リチウムにてｐＨを調整し、限外濾過膜により脱塩濃縮し顔料濃度１０重量％のカーボンブラック分散液とした。このものを１ミクロンのナイロンフィルターで濾過しカーボンブラック液２とした。平均粒子径は８０ｎｍであった。
【０１２１】
（参考例３）ジアゾ化合物処理したカーボンブラック分散液３
表面積が２３０ｍ^２／ｇでＤＢＰ吸油量が７０ｍｌ／１００ｇのカーボンブラック１００ｇと、ｐ−アミノ−Ｎ−安息香酸３４ｇとを水７５０ｇに混合分散し、これに硝酸１６ｇを滴下して７０℃で撹拌した。５分後、５０ｇの水に１１ｇの亜硝酸ナトリウムを溶かした溶液を加え、更に１時間撹拌した。得られたスラリーを１０倍に希釈し遠心処理し粗大粒子を除き、ｐＨをジエタノールアミンにて調整しｐＨ８〜９とし、限外濾過膜にて脱塩濃縮し顔料濃度１５％のカーボンブラック分散液とした。このものをポリプロピレンの０．５μｍフィルターにてカーボンブラック分散液３とした。平均粒子径は９９ｎｍであった。
【０１２２】
（参考例４）ジアゾ化合物処理したカーボンブラック分散液４
２リットルの水と４３ｇのスルファニル酸を含む約７５℃の溶液を、撹拌しながら、２３０ｍ^２／ｇの表面積と７０ｍｌ／１００ｇのＤＢＰＡを有する２０２ｇのカーボンブラックに添加した。この混合物を撹拌しながら室温まで冷やし、２６．２ｇの濃硝酸を添加した。水中の亜硝酸ナトリウムの２０．５ｇの溶液を添加した。４−スルホベンゼンジアゾニウム水酸化物内部塩を作製し、これをカーボンブラックと反応させた。発生した泡立ちが停止するまで分散系を撹拌した。得られたスラリーを希釈し、水酸化リチウムにてｐＨを調整しｐＨ８〜９として粗大粒子を遠心処理にて除き、引き続いて限外濾過膜にて脱塩濃縮し顔料濃度１５％のカーボンブラック分散液とした。このものをポリプロピレンの１μｍフィルターにて濾過しカーボンブラック分散液４とした。平均粒子径は９５ｎｍであった。
【０１２３】
（参考例５）表面化学処理したカラー顔料分散液
（イエロー分散液１、マゼンタ分散液１、シアン分散液１）
イエロー顔料としてＣ．Ｉ．ピグメントイエロー１２８を低温プラズマ処理しカルボン酸基を導入した顔料を作製した。これをイオン交換水に分散したものを限外濾過膜にて脱塩濃縮し顔料濃度１５％のイエロー顔料分散液１とした。平均粒子径７０ｎｍであった。
同様にマゼンタ顔料としてＣ．Ｉ．ピグメントマゼンタ１２２を用いて顔料濃度１５％のマゼンタ顔料分散液１を作製した。平均粒子６０ｎｍであった。
同様にシアン顔料としてＣ．Ｉ．ピグメントシアン１５：３を用いて顔料濃度１５％のシアン顔料分散液１を作製した。平均粒子径８０ｎｍであった。
【０１２４】
本発明では界面活性剤を使用することで記録紙への濡れ性を改善することができる。好ましい界面活性剤としては界面ポリオキシエチレンアルキルエーテル酢酸塩、ジアルキルスルホ琥珀酸塩、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンポリオキシプロピレンブロック共重合体、アセチレングリコール系界面活性剤が挙げられる。より具体的にはアニオン系界面活性剤としてはポリオキシエチレンアルキルエーテル酢酸塩（Ｉ）、及び／または炭素鎖が５〜７の分岐したアルキル鎖を有するジアルキルスルホ琥珀酸（II）を用いることで普通紙特性も改善されさらに着色剤の溶解・分散安定性が選られる。
【０１２５】
【化７】
Ｒ_１−Ｏ−（ＣＨ_２ＣＨ_２Ｏ）ｍＣＨ_２ＣＯＯＭ ……（Ｉ）
（Ｒ_１：炭素数６〜１４の分岐してもよいアルキル基、ｍ：３〜１２、Ｍ：アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、アルカノールアミン）
【０１２６】
【化８】

（Ｒ_２：炭素数５〜１６の分岐したアルキル基、Ｍ：アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、アルカノールアミン）
【０１２７】
【化９】

（Ｒ：分岐しても良い６〜１４の炭素鎖、ｋ：５〜２０）
【０１２８】
【化１０】
Ｒ−（ＯＣＨ_２ＣＨ_２）ｎＯＨ ……（IV）
（Ｒ：分岐しても良い炭素数６〜１４の炭素鎖、ｎ：５〜２０）
【０１２９】
【化１１】

（Ｒ’：炭素数６〜１４の炭素鎖、ｍ，ｎ：ｍ，ｎ≦２０）
【０１３０】
【化１２】

（ｐ，ｑ：０〜４０）
【０１３１】
さらに本発明の界面活性剤の対イオンとしてリチウムイオン、及び下記一般式で示される第４級アンモニウム、第４級ホスホニウムを用いることにより界面活性剤が優れた溶解安定性を示す。
好ましい非イオン系の界面活性剤としてポリオキシエチレンアルキルフェニルエーテルである一般式（III）、アセチレングリコール系界面活性剤である一般式（VI）の活性剤が挙げられる。これらを併用することによりさらに相乗効果として浸透性が挙げられ、これにより色境界にじみが低減されまた文字にじみも少ないインクが得られる。
なお、このインクのｐＨを６以上にすることによりインクの保存安定性が得られ、また、オフィスで使用されているコピ−用紙や用箋等はｐＨが５〜６のものが多く、これらの記録紙にインクを９〜６０μｍの微細な吐出口より吐出し重量が３ｎｇ〜５０ｎｇの液滴として５〜２０ｍ／ｓで飛翔させ、単色での付着量を１．５ｇ／ｍ^２から３０ｇ／ｍ^２としてＪＩＳ Ｐ−８１２２試験法によるステキヒトサイズ度が３秒以上の所謂普通紙に記録するこにより高画質、高解像の記録画像を形成する記録方式を提供することができる。ただし、ｐＨが９以上では保存時に（II）の活性剤では分解による物性変化が起こりやすいため（II）を用いる場合はｐＨを６〜９とすることが好ましい。
【０１３２】
本発明に用いることができる前記（Ｉ）、（II）、（III）、（IV）、（Ｖ）、（VI）の添加量は０．０５〜１０重量％の間でプリンターシステムにより要求されるインク特性に対し所望の浸透性を与えることが可能である。ここで０．０５％未満ではいずれの場合も２色重ね部の境界でのにじみが発生し、１０重量％以上添加する場合は化合物自体が低温で析出しやすことがあり信頼性が悪くなる。
次表８に本発明に用いる界面活性剤（Ｉ）、（II）を具体的に遊離酸型で示す。
【０１３３】
【表８】

【０１３４】
下記実施例に使用するエマルジョンは有機超微粒子の合成例で作製したエマルジョン［１］〜［８］である。
実施例１
下記処方のインク組成物を作成し、ｐＨが９になるように水酸化リチウム１０％水溶液にて調整した。その後、平均孔径０．８μｍのメンブレンフィルターで濾過を行ないインク組成物を得た。
カーボン分散液１ ８．０ｗｔ％
２−メチル−２，４−ペンタンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
２−ピロリドン ５．０ｗｔ％
具体例（Ｉ−１）の活性剤 ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［１］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１３５】
実施例２
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化ナトリウムで９にしてインク組成物を調製した。
カーボン分散液２ １０．０ｗｔ％
１，６−ヘキサンジオール ３０．０ｗｔ％
グリセロール １０．０ｗｔ％
Ｎ−メチル−２−ピロリドン ２．０ｗｔ％
具体例（Ｉ−２）の活性剤 ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
エマルジョン［２］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１３６】
実施例３
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化ナトリウムで９にしてインク組成物を調製した。
カーボン分散液３ １２．０ｗｔ％
プロピレングリコール ２０．０ｗｔ％
グリセロール １０．０ｗｔ％
Ｎ−ヒドロキシエチル−２−ピロリドン ５．０ｗｔ％
具体例（Ｉ−３）の活性剤 ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［３］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１３７】
実施例４
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
カーボン分散液４ １０．０ｗｔ％
１，３−ブタンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
２−ピロリドン ５．０ｗｔ％
具体例（Ｉ−４）の活性剤 ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
エマルジョン［４］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１３８】
実施例５
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
エマルジョン被覆型カーボンブラック分散液（花王社製） ９．０ｗｔ％
２，３−ブタンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
Ｎ−メチル−２−ピロリドン ３．０ｗｔ％
具体例（Ｉ−５）の活性剤 ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１３９】
実施例６
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
自己分散型カーボンブラック分散液（東洋インキ社製） １０．０ｗｔ％
１，４−ブタンジオール １５．０ｗｔ％
グリセロール １５．０ｗｔ％
Ｎ−ヒドロキシエチル−２−ピロリドン ５．０ｗｔ％
具体例（Ｉ−６）の活性剤 ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
エマルジョン［５］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４０】
実施例７
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
カルボキシル基付加型カーボンブラック １３．０ｗｔ％
（キャボット・スペシャルティ・ケミカルズ・インク社製）
１，３−プロパンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
２−ピロリドン ５．０ｗｔ％
具体例（II−１）の活性剤 ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［６］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４１】
実施例８
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
スルホン基付加型カーボンブラック １４．０ｗｔ％
（キャボット・スぺシャルティ・ケミカルズ・インク社製）
２−メチル−２，４−ペンタンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
Ｎ−メチル−２−ピロリドン ２．０ｗｔ％
具体例（II−２）の活性剤 ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
エマルジョン［７］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４２】
実施例９
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
カルボキシル基付加型カーボンブラック １０．０ｗｔ％
（オリエント化学工業社製）
１、５−ペンタンジオール １５．０ｗｔ％
グリセロール １５．０ｗｔ％
Ｎ−ヒドロキシエチル−２−ピロリドン ２．０ｗｔ％
具体例（II−３）の活性剤 ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［８］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４３】
実施例１０
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
マイクロカプセル包含型カーボンブラック １１．０ｗｔ％
（大日本インキ化学工業社製）
１，６−ヘキサンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
２−ピロリドン ３．０ｗｔ％
具体例（II−４）の活性剤 ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４４】
実施例１１
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化ナトリウムで９にしてインク組成物を調製した。
カルボキシル基付加型自己分散型カーボンブラック分散液
（大成化工社製） ８．０ｗｔ％
２−メチル−２，４−ペンタンジオール ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
Ｎ−メチル−２−ピロリドン ５．０ｗｔ％
具体例（III）の活性剤（Ｒ＝Ｃ６，ｋ＝５） ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［１］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４５】
カラー顔料インク
（シアン顔料インク）
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
シアン分散液１ ６．０ｗｔ％
尿素 ２２．５ｗｔ％
グリセロール ７．５ｗｔ％
Ｎ−ヒドロキシエチル−２−ピロリドン ５．０ｗｔ％
ＥＣＴＤ−３ＮＥＸ
（日光ケミカルズ製アニオン系界面活性剤） ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［２］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４６】
（マゼンタ顔料インク）
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
マゼンタ分散液１ ６．０ｗｔ％
１，３−ジメチルイミダゾリジノン １５．０ｗｔ％
グリセロール １５．０ｗｔ％
２−ピロリドン ５．０ｗｔ％
ＥＣＴＤ−６ＮＥＸ
（日光ケミカルズ製アニオン系界面活性剤） ２．０ｗｔ％
２，２，４−トリメチル−１，３−ペンタンジオール ２．０ｗｔ％
エマルジョン［３］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４７】
（イエロー顔料インク）
下記組成物を用いる以外は実施例１と同様にし、ｐＨを水酸化ナトリウムで９にしてインク組成物を調製した。
イエロー分散液１ ６．０ｗｔ％
マルチトース ２５．０ｗｔ％
グリセロール １５．０ｗｔ％
Ｎ−メチル−２−ピロリドン ５．０ｗｔ％
ディスパノールＴＯＣ
（日本油脂製ノニオン系界面活性剤） ２．０ｗｔ％
２−エチル−１，３−ヘキサンジオール ２．０ｗｔ％
エマルジョン［４］ ３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４８】
比較例１
下記処方のインク組成物を作成し、ｐＨが９になるように水酸化リチウム１０％水溶液にて調整した。その後、平均孔径０．８μｍのメンブレンフィルターで濾過を行ないインク組成物を得た。
高分子分散剤分散型カーボンブラック
（大日精化工業社製） ５．０ｗｔ％
ジエチレングリコール １５．０ｗｔ％
グリセロール ５．０ｗｔ％
Ｎ−メチル−２−ピロリドン ２．０ｗｔ％
ＥＣＴＤ−６ＮＥＸ
（日光ケミカルズ製アニオン系界面活性剤） １．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１４９】
比較例２
下記組成物を用いる以外は比較例１と同様にし、ｐＨを水酸化リチウムで９にしてインク組成物を調製した。
界面活性剤分散型カーボンブラック（富士色素社製） ５．０ｗｔ％
トリエチレングリコール １５．０ｗｔ％
グリセロール ５．０ｗｔ％
Ｎ−ヒドロキシエチル−２−ピロリドン ２．０ｗｔ％
ディスパノールＴＯＣ
（日本油脂社製ノニオン系界面活性剤） １．０ｗｔ％
エマルジョン（マイクロジェル溶液固形分２０．０％日本ペイント製）
３．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１５０】
比較例３
下記組成物を用いる以外は比較例１と同様にし、ｐＨを水酸化ナトリウムで９にしてインク組成物を調製した。
高分子分散剤分散型カーボンブラック（御國色素社製） ５．０ｗｔ％
エチレングリコール １５．０ｗｔ％
グリセロール ５．０ｗｔ％
２−ピロリドン ２．０ｗｔ％
ＥＣＴＤ−６ＮＥＸ
（日光ケミカルズ製アニオン系界面活性剤） １．０ｗｔ％
プロキセルＬＶ（防腐剤） ０．２ｗｔ％
イオン交換水 残量
【０１５１】
実施例１〜１１とシアン、マゼンタ、イエロー顔料インク及び比較例１〜３のインク組成物の粘度を表９に示す。
【０１５２】
【表９】

【０１５３】
次に、上記実施例１〜１１及び比較例１〜３について、前記のヘッドを固定したインクジェット印字装置を用いて下記の試験を行ない、評価した。
１）画像の鮮明性
印字乾燥後、２色重ね部境界の滲み、画像滲み、色調、画像濃度を３０人の評価被験者及び反射型カラー分光測色濃度計（Ｘ−Ｒｉｔｅ社製）により総合的に調べ、後に示す評価基準にしたがって判定した。用いた印刷試験用紙を以下に示す
▲１▼マイペーパー（株式会社ＮＢＳリコー製）
▲２▼紙源Ｓ・再生紙（株式会社ＮＢＳリコー製）
▲３▼ＰＢ紙（キャノン株式会社製）
▲４▼マルチエース（富士ゼロックスオフィスサプライ株式会社製）
▲５▼やまゆり紙（本州製紙株式会社製・再生紙）
▲６▼ＬＨ紙（富士ゼロックスオフィスサプライ株式会社製）
▲７▼Ｘｅｒｏｘ ４０２４紙（富士ゼロックスオフィスサプライ株式会社製）
▲８▼Ｎｅｅｎａｈ Ｂｏｎｄ紙（キンバリークラーク社製）
【０１５４】
２）画像の乾燥性
印字後の画像に一定条件で濾紙を押しつけインクが濾紙に転写しなくなるまでの時間を測定した。いずれの紙でも１０秒以内で乾燥した場合に○と判定した。
【０１５５】
３）保存安定性
各インクをポリエチレン容器に入れ、−２０℃、５℃、２０℃、７０℃でそれぞれの条件下で３カ月保存し、保存後の表面張力、粘度、及び沈殿物析出の有無を調べた。どの条件で保存しても、物性等の変化がないものを○とした。
【０１５６】
４）印字休止時の信頼性
ヘッドを固定したインクジェット印字装置の動作中にキャップ、クリーニング等が行なわれないでどれだけ印字休止しても復帰できるかを調べ、どれだけの時間（秒）で噴射方向がずれるか、あるいは吐出液滴の重量が変化するかでその信頼性を評価した。
【０１５７】
５）コックリング評価
印字された各用紙の印字直後のコックリングを物差しで測り、次のように評価した。
◎：コックリングが全く起きていない。
□：コックリングが起きているが５ｍｍ以内の範囲で起きている。
△：コックリングが５ｍｍから１ｃｍの範囲で起きている。
×：コックリングが１ｃｍ以上起きている。
【０１５８】
【表１０】

【０１５９】
（請求項１の説明）
図５は、被印字媒体として普通紙を利用し、その普通紙上に本発明のインクでもってベタ画像部（５１．０［ｍｍ］×１４９．０［ｍｍ］の一定面積領域）にインク液滴を付着させ、そのときの紙上の単位面積当たりのインク滴付着量（Ｇｍ）を変化させたときの値と、そのベタ画像部の画像濃度値（光学濃度：ＯＤ値）との関係を実験的に調査した結果を表わしたものである。
ここで、インク液滴の単位面積当たりの付着量（Ｇｍ）の測定方法としては、ベタ画像部を任意の画像解像度に設定し（例えば７２０ｄｐｉなど）、その解像度を印字密度（印字率）１００％で印字した場合に、紙上に付着したインク滴重量［ｇ］を電子天秤等で計測し、その計測された重量［ｇ］を上記ベタ画像部の印字領域面積［ｍ^２］で除することにより、求めることができる。また、ベタ画像部の画像濃度（ＯＤ値）については、Ｘ−Ｒｉｔｅ社製反射型分光濃度計（Ｘ−Ｒｉｔｅ９３８型）等を利用し、画像の表側より被印字ベタ画像部での反射率分光濃度として計測したものである。
ところで、画像品質として全体の画像が見やすくなる適正な光学濃度（ＯＤ）値としては、通常、ベタ画像部においてＯＤ＝１．２以上の値が必要である。したがって、図５のように、例えば、ＮＢＳリコー社製普通用紙（商品名：マイペーパーＴＡ）Ａを利用して、適正な画像濃度（ＯＤ）値であるＯＤ＝１．２以上の値をベタ画像部にて得ようとする場合には、前記して求めた単位面積当たりのインク滴付着量（Ｇｍ）の値を５［ｇ／ｍ^２］以上とすることにより、必要な画像濃度値（ＯＤ＝１．２以上の値）を達成し得ることができる。また、例えば、紙種が異なって、ＯＡペーパー用紙やペーパーライン用紙のような海外製の普通用紙Ｂのように比較的画像濃度が出難い紙種利用の場合には、適正な画像濃度（ＯＤ）値を得るためには、前記単位面積当たりのインク滴付着量（Ｇｍ）の値を１０［ｇ／ｍ^２］以上とすることにより、必要な画像濃度値（ＯＤ＝１．２ 以上の値）を達成し得ることができる。
【０１６０】
更に、上記単位面積当たりのインク滴付着量（Ｇｍ）を増大させることにより、ベタ画像部での画像濃度（ＯＤ）値を最大値であるＯＤ＝１．７（紙種Ａの場合）、もしくはＯＤ＝１．５（紙種Ｂの場合）程度まで増大させることはできるものの、何れの紙種（Ａ、Ｂ）でもインク滴付着量（Ｇｍ）が４０［ｇ／ｍ^２］以上の範囲ではベタ画像部での画像濃度（ＯＤ）値は飽和状態にあるため、それ以上インク滴付着量（Ｇｍ）を増加させても画像濃度（ＯＤ）値を増大させる効果はほとんどないことが実験的に判明した。
【０１６１】
したがって、本発明のインクジェット印字装置の場合、上記した本発明でのインクを使用して普通紙上に印字する場合には、前記インク液滴の単位面積当たりの付着量の範囲を５〜４０［ｇ／ｍ^２］の値に調整可能とすることにより、画像品質として適正な画像濃度（ＯＤ）値が得られるインクジェット印字装置を提供することが可能となる。なお、本発明のインクジェット装置の場合には、図４に示されるインクを加圧してインク液滴を吐出せしめる印字ヘッド（インクジェットヘッド）（１４）において、そのヘッド（１４）を駆動する駆動信号を調整して、そのヘッド（１４）の各ノズルより吐出されるインク吐出量を調整可能な手段を設けることにより、上記被印字媒体上での単位面積当たりのインク付着量を調整可変とすることが可能となる。
【０１６２】
なお、前記紙とインク滴との間で形成される前進接触角の測定方法については、先に記載の通り、協和界面科学社製の自動接触角計を用いて計測し、約５μｌ程度のインク量を紙に接触させた後、その１ｓｅｃ後に紙とインクとの間に形成される前進接触角の値を読み取ったものを表わしている。
また、コックリングの測定においても、前記インク液滴の単位面積当たりの付着量の範囲を５〜４０［ｇ／ｍ^２］の値に調整可能とすることにより、コックリングが殆ど起きないことが確認できた。
【０１６３】
（請求項２及び４の説明）
本発明のインクジェット印字装置では、水、着色剤、水溶性有機溶媒、界面活性剤などを含有するインクを用いることができ、水溶性有機溶媒や界面活性剤の種類、含有量などを調整することにより、所望のブリストー法における被印字媒体へのぬれ時間および吸収係数を有するインクを得ることができる。ブリストー法における被印字媒体へのぬれ時間および吸収係数は、図１に示す浸透性測定装置を用いて次のようにして求めることができる。
【０１６４】
＜試験条件＞
すなわち、図１において、インクジェット印字用インク（５１）が４０μｌ入ったインク溜め（５２）を回転ホイール（５３）の周面に密着して特定の移動速度で移動している印字用紙（マイペーパー、ＮＢＳリコー社製）（５４）に接触させ、インク溜めのスリット（スリット幅１ｍｍ、スリット長さ１７．５ｍｍ）を通して印字用紙面にインクを吸収させることにより印字用紙面上に図２に示すインク転移跡を得て、次式からインクの接触時間ｔとインクの転移量Ｖを求める。
【数２】
接触時間ｔ（ｍｓ）＝スリット幅ｄ（ｍｍ）×１０００／紙の移動速度Ｓ（ｍｍ／秒）
転移量Ｖ（ｍｌ／ｍ^２）＝インク量Ｑ（μｌ）×１０００／（インク転移跡の長さＬ（ｍｍ）×スリット長さｗ（ｍｍ））
【０１６５】
次に、印字用紙（５４）の移動速度を変化させて、それぞれの移動速度の場合におけるインクの接触時間ｔとインクの転移量Ｖを同様に求める。上記のようにして求められたインクの接触時間ｔとインクの転移量Ｖから、ｔ^１／２に対してＶをプロットし、図３に示すようなインクの印字用紙への吸収曲線を描き、インク吸収曲線が横軸に対して平行である間の時間をぬれ時間、それ以降のインク吸収曲線の傾きをインク吸収係数として、それぞれの値を求めることができる。
そこで、上記ブリストー法により、本発明インクを使用した場合での前記各紙種Ａ、Ｂにおけるインク吸収係数を測定した結果、紙種Ａの場合にはインク吸収係数が８〜９［ｍｌ／ｍ^２／ｍｓ^１／２］程度の値を示し、また、紙種Ｂの場合にはインク吸収係数が３〜４［ｍｌ／ｍ^２／ｍｓ^１／２］程度の値を示すことが判明した。
【０１６６】
そこで、図６では、上記インク吸収係数が異なる紙種Ａ、及びＢについて、前記ベタ画像部での単位面積当たりのインク滴付着量（Ｇｍ）の値を変化させたときの、そのベタ画像部での粒状度との関係について、実験的に調査した結果を表わしている。ここで、本発明で言う粒状度とは、以下のように定義して測定したもののことをいう。すなわち、印字された上記ベタ画像部を被測定画像部とし、その画像部に対して、解像度１０００ｄｐｉ相当のスキャナ装置でもってＲＧＢカラーモードにて測定画像の読み込みを行なう。次に、その読み込みまれた画像データ（ＲＧＢ）を色度（ＣＩＥ（１９７６）Ｌ^＊ａ^＊ｂ^＊）データに変換し、その色度データをフーリエ変換して、ウィーナスペクトラムＷＳ_ｂ（ｕ）、ＷＳ_ｃ１（ｕ）、ＷＳ_ｃ２（ｕ）を得る。ＷＳ_ｂ（ｕ）は明度成分、ＷＳ_ｃ１（ｕ）、ＷＳ_ｃ２（ｕ）は色度成分に対するウィーナスペクトラムを表わす。このフーリエ変換後のウィーナスペクトラムは複素平面における原点を中心に０〜１８０度の範囲で円周方向に平均をとることでデータの１次元化を図っている。次に、カラー粒状度（ＣＧ）として、次式で表わせるものを定義とする。
【０１６７】
【数３】

視覚の空間周波数特性であるＶＴＦは以下の式で表わされる。
【数４】
ＶＴＦ＝５．０５・ｅｘｐ（−０．１３８・ｆｆ）・（１．０ｅｘｐ（−０．１・ｆｆ）
ここで、ｆｆは、網膜上の空間周波数特性を意味する。
ｈ（Ｌ^＊）は平均明度に対する補正関数であり、以下の式で表わされる。
【０１６８】
【数５】

ここで、ｔ_１＝０．０１０４４、ｔ_２＝０．８９７８である。
また、上記式での重み係数としてＰ_Ｌ＊、Ｐ_ａ＊、Ｐ_ｂ＊を以下の値に設定する。
Ｐ_Ｌ＊＝１．４０５２
Ｐ_ａ＊＝１．１４６
Ｐ_ｂ＊＝０．５４８
【０１６９】
次に、メディアンフィルタを用いて、パワースペクトラム内のスパイク状のスペクトル成分のみを除去した近似カーブを算出する。次に、明度成分のパワースペクトラムと前記の近似カーブとの差分、つまりスパイク状のスペクトル成分のみを抽出し、その総和をテクスチャ成分（Ｔ_Ｘ）とする。そして、最終的には上記各値を次式に代入し、「総合粒状度」と定義して、各インク付着量値でのベタ画像に対する粒状度として測定を行なった。
総合粒状度＝α・ＣＧ＋β・Ｔ_Ｘ＋ｃｏｎｓｔ
（ここで、α＝０．４１５７８７３、β＝３．９０６０２９３、ｃｏｎｓｔ＝０．０５３１０９の値が設定される。）
【０１７０】
すなわち、「総合粒状度」の値が小さいほど、ベタ画像部にてザラツキ感の少ない平滑・均一なベタ画像（インク滴で均一に埋まっているベタ画像）が描かれているということである。
なお、粒状度の測定方法（粒状性評価尺度）としては、上記方法以外に銀塩写真等の評価で用いられているＡＮＳＩ ＰＨ−２．４０−１９８５「root mean square (rms) granularity of film」に規定された濃度分布Ｄｉの標準偏差で定義される下式の「ＲＭＳ粒状度」を用いる方法や、ハードコピー画像（電子写真等）の分野で広く用いられているXerox社のDooleyとShawの提案によるＮＷＳ（ノイズウィーナスペクトラム）を適用し、視覚の空間周波数特性（Visual Transfer Function：ＶＴＦ）とカスケ−ドした後に積分した値で定義される下式の「粒状性（Graininess Scale：ＧＳ）」を用いる方法を適用しても良いが、インクジェット画像の場合には前記した「総合粒状度」を用いる方法が最も明確な粒状度が得られるため、より好ましい。
【数６】
ＲＭＳ粒状度（σ_Ｄ）＝［１／ＮΣ（Ｄｉ−Ｄ）^２］^１／２
【０１７１】
【数７】

（ここでｕは空間周波数、ＷＳ_Ｄ（ｕ）はウィーナスペクトラム、ｅｘｐ（−１．８Ｄ）の項は濃度と人の知覚する明るさの差を補正するために主観評価実験により求められた平均濃度Ｄを変数とした関数である。）
【０１７２】
したがって、図６の結果（関係図）では、前記インク吸収係数が大きい（８〜９［ｍｌ／ｍ^２／ｍｓ^１／２］程度）紙種Ａや、比較的インク吸収係数が小さい（３〜４［ｍｌ／ｍ^２／ｍｓ^１／２］程度）紙種Ｂの場合に、前記単位面積当たりのインク滴付着量（Ｇｍ）の値が比較的小さい範囲では、ベタ画像部での白スジ等が目に付き、所望の画像がインク滴で均一に埋め尽くされる状態とならないため、ザラツキ感（粒状感）が感じられる。その視覚感覚は前記「総合粒状度」の値としては、図６のように比較的高い値として現れる。また、前記インク滴付着量（Ｇｍ）を増加させることにより、紙種Ａの場合には１０〜４０［ｇ／ｍ^２］の範囲内、紙種Ｂの場合には１５［ｇ／ｍ^２］以上とすることにより、ベタ画像部での粒状度の値を最も低くすることができ、本発明インクを使用した場合でもベタ画像部で白スジがなく、所望のインク滴で均一に埋まった画像を得ることができる。そして、更に、前記インク滴付着量（Ｇｍ）を増加させることで、両紙種（Ａ or Ｂ）ともに普通紙上での印字ムラが顕著に現れてくるため、前記単位面積当たりのインク滴付着量（Ｇｍ）の値が比較的大きい範囲にて、再度、またザラツキ感（粒状感）が感じられ、前記「総合粒状度」の値も図６のように高くなるという傾向を示している。
【０１７３】
したがって、本発明のインクジェット印字装置の場合、上記した本発明でのインクを使用して各々のインク吸収係数を有する紙種Ａ、及びＢの普通紙上に印字する際には、各紙種のインク吸収係数に応じて、そのインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］を超える場合には、前記インク液滴の単位面積当たりの付着量を１０〜４０［ｇ／ｍ^２］の範囲内の値に調整し、あるいはインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］以下の場合には、前記インク液滴の単位面積当たりの付着量を１５［ｇ／ｍ^２］以上の値に調整して印字することにより、インクを吸収し易い紙（紙種Ａ）や吸収し難い紙（紙種Ｂ）など、あらゆる紙種に対してベタ画像部等で白スジのない、適正で安定した画像品質が得られるインクジェット印字装置を提供することが可能となる。
また、コックリングの測定においても、前記インク液滴の単位面積当たりの付着量の範囲をこの値に調整可能とすることにより、コックリングが殆ど起きないことが確認できた。
【０１７４】
（請求項６の説明）
図７では、被印字媒体として普通紙を利用し、その普通紙上に本発明のインクでもってベタ画像部（１０．０［ｍｍ］×１０．０［ｍｍ］の一定面積領域）にインク液滴を付着させ、前記したベタ画像部を印字密度（印字率）１００％で印字した場合に、そのベタ画像から得られる紙上の単位面積当たりのインク滴付着量（Ｇｍ）の値を変化させたときの、そのベタ画像部での裏抜け濃度との関係を実験的に調査した結果を表わしたものである。ここで、本発明で言う裏抜け濃度とは、以下のように定義して測定したもののことをいう。
すなわち、前記したベタ画像部について、Ｘ−Ｒｉｔｅ社製反射型分光濃度計（Ｘ−Ｒｉｔｅ ９３８型）等を利用し、その対象画像の紙の裏側からの反射率分光濃度（Ｄｒ）を計測する。そして、そのベタ画像を印字した紙の地肌濃度（Ｄｇ）について同様の計測方法にて計測した後、そのベタ画像の裏側からの測定濃度（Ｄｒ）から上記印字した紙の地肌濃度（Ｄｇ）を差し引いた濃度差（Ｄｒ−Ｄｇ）を裏抜け濃度と定義して、各インク付着量値での裏抜け濃度の測定を行なった。つまり、裏抜け濃度値が小さいほど、紙の裏側でのインク裏写りが少なく、より紙の元々の地肌に近い色になっているということである。このインク裏写り現象の問題は、従来より普通紙において顕著に現れており、特に、普通紙に両面印字をしようとする際に紙の裏側での印字画像が読みづらくなる問題を有している。
【０１７５】
したがって、普通紙の裏側での印字画像の可読性の妨げにならない適正な裏抜け濃度値としては、実験的に０．１以下の値にすることが好ましい。図７の調査結果（関係図）より、例えば、ＮＢＳリコー社製普通用紙（商品名：マイペーパーＴＡ）Ａを利用して、適正な裏抜け濃度値である０．１以下の値を得ようとする場合には、前記した単位面積当たりのインク滴付着量（Ｇｍ）の値を約３０［ｇ／ｍ^２］以下の値とすることにより、適正な裏抜け濃度値である０．１以下の値を達成し得ることが判明した。また、例えば、紙種が異なって、ＯＡペーパー用紙やペーパーライン用紙のような海外製の普通用紙Ｂを利用した場合には、適正な裏抜け濃度値とするためには、前記単位面積当たりのインク滴付着量（Ｇｍ）の値は約３８［ｇ／ｍ^２］以下の値であれば充分達成でき、約３０［ｇ／ｍ^２］の値のときでは、インク裏写りがほとんど気にならないレベルにまで達成できることが実験的に判明した。
【０１７６】
したがって、本発明のインクジェット印字装置の場合、上記した本発明でのインクを使用して普通紙の表面側に印字された後、その裏面側にも印字したい場合には、前記インク液滴の単位面積当たりの付着量の値を約３０［ｇ／ｍ^２］以下の値に調整可能とすることにより、普通紙の裏面側でも印字画像が読みやすく、両面印刷に適したインクジェット印字装置を提供することが可能となる。
【０１７７】
（請求項３と５の説明）
表１１及び表１２は、本発明にて前記したベタ画像についての画質評価項目（図５、図６、図７）に加えて、文字画像やカラー画像における「文字滲み（フェザリング）」と「カラーブリード」の画質評価と、それら上記全ての画質評価項目を加味・考慮した「総合画質評価」のレベルについて、評価被験者３０人に対し前記インク液滴の単位面積当たりの付着量の値を順次変化させた場合での各画像品質レベルについて主観評価した結果をまとめたものである。なお、表中の各記号の意味は以下の通りである。
【０１７８】
＜「フェザリング」、及び「カラーブリード」の評価記号＞
◎：滲んでいなく、画像が見やすい（適正である）。
□：滲んでいないが、画像が見難い（不適正である）。
△：滲んでいるが、許容できる。
×：滲んでいて、許容できない。
【０１７９】
＜「総合評価」の評価記号＞
Ａ：従来より非常に良い。
Ｂ：従来より良い。
Ｃ：従来と変わらず。
Ｄ：従来より悪い。
【０１８０】
表１１は、紙種として前記したインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］を超える紙種Ａに対して実施した結果である。表１１の結果より、評価被験者３０人の画質主観評価にて、上記した「総合評価」として適正なインク滴付着量であると判断される最適範囲（評価記号が「Ａ」である範囲）は、１０〜２０［ｇ／ｍ^２］の値であることが判明した。
また、表１２は、表１１と同様の評価条件にて評価した結果であり、紙種として前記したインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］以下を示す紙種Ｂに対して実施した結果である。表１２の結果より、評価被験者３０人の画質主観評価にて、上記した「総合画質評価」として適正なインク滴付着量であると判断される最適範囲（評価記号が「Ａ」である範囲）は、１５〜３０［ｇ／ｍ^２］の値であることが判明した。
【０１８１】
したがって、本発明のインクジェット印字装置の場合には、上記した本発明でのインクを使用して各々のインク吸収係数を有する紙種Ａ、及び紙種Ｂの普通紙上に印字する際に、各紙種のインク吸収係数に応じて、そのインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］を超える場合には、前記インク液滴の単位面積当たりのインク滴付着量を好ましくは１０〜２０［ｇ／ｍ^２］の範囲の値に調整可能とし、あるいはインク吸収係数の値が６［ｍｌ／ｍ^２／ｍｓ^１／２］以下を示す場合には、前記インク液滴の単位面積当たりのインク滴付着量を好ましくは１５〜３０［ｇ／ｍ^２］の範囲の値に調整可能として印字することにより、インクを吸収し易い紙（紙種Ａ）や吸収し難い紙（紙種Ｂ）など、紙種の違いに依らず、あらゆる紙種に対して文字画像部やカラー画像（グラフィック画像）部等で、フェザリング現象やカラーブリード現象、更にはコックリング現象のない高品質な画像が得られ、また、ベタ画像部においても白スジ画像の発生がなく、文字・画像等で適正な印字濃度が得られ、更に、裏抜け濃度も低い安定して高品位な画像品質が得られるインクジェット印字装置を提供することが可能となる。
【０１８２】
【表１１】

【０１８３】
【表１２】

【０１８４】
【発明の効果】
以上、詳細かつ具体的な説明より明らかなように、本発明の請求項１によれば、固定されたヘッドからインク滴を熱エネルギーまたは機械エネルギーにより微小な液滴として飛翔させ被記録材に付着させて記録を行なうインクジェット記録方法において、新規なインク構成による記録液を用い、普通紙に印字した場合でも画像解像度に依らず文字・画像等が充分見えやすい印字濃度（ＯＤ値：１．２以上）でもって、より高い画像濃度が得られるようになるため、高速印刷をした場合でも、コックリングが殆ど起こらずに、より鮮明で印字品質の高いカラー画像を出力することができるインクジェット印字装置が提供される。また、請求項２、４によれば、普通紙の紙種の違いに依らず、ベタ画像部等で紙の地肌の白スジ画像が発生しない（ベタ部がほぼ均一に埋まる）高い画像品質が得られるようになるので、比較的より少ないインク量で文字・画像等の裏写り問題が少なく、両面、及び高速印刷に適したカラー画像を出力することができるインクジェット印字装置が提供される。また、請求項３、５によれば、普通紙の紙種の違いに依らず、文字や画像の滲み（フェザリング現象やカラーブリード現象）、コックリングが少なく、裏抜け濃度も低い良好な画像品質が得られるようになるので、両面、及び高速印刷をした場合でも、普通紙において、更により鮮明で高画質なカラー画像を出力することができるインクジェット印字装置が提供される。また、請求項６によれば、普通紙の紙種の違いに依らず、比較的裏抜け濃度が低くなる良好な画像品質が得られるようになるので、文字・画像等の裏写り問題が少なく、両面印刷に適したカラー画像を出力することができるインクジェット印字装置が提供される。また、請求項８〜１５に記載の自己分散性顔料を用いることにより、再溶解性に優れた信頼性の高い顔料インクを設計することが可能となり、高密度のラインヘッドに対応したインクが提供される。インク中の顔料濃度が８ｗｔ％以上、好ましくは１０ｗｔ％以上にすることである。顔料濃度を高めることにより、インクの粘度が高くなり、顔料が紙面上で凝集し易くなり画像濃度（ＯＤ）が向上すると共にフェザリングも少なくなる。また、請求項１６〜２１に記載の記録液は、高顔料濃度で高粘度インクであるが、選定された湿潤剤の効果により従来の高顔料・高粘度インクに比べノズルの目詰まりとコックリングがなく、安定した印字が可能となった。更に、保存安定性が格段に向上した。従来用いられてきたエチレングリコール（ジエチレングリコール）とグリセリンの混合した低粘度の湿潤剤よりも、２−メチル−２，４−ペンタンジオール（１，３−ブタンジオール、１，６−ヘキサンジオール）とグリセリンの混合した高粘度の湿潤剤を用いることにある。高粘度の湿潤剤を用いると、高顔料濃度と相まって高粘度のインクを達成できる。また、本発明の請求項２２〜２５により、アルキルエーテルや炭素数８以上のポリオールと（Ｉ）〜（VI）の界面活性剤の相互作用により、インクの表面張力が４０ｄｙｎ／ｃｍ以下となり、顔料濃度が６ｗｔ％以上、８．０ｃｐｓ以上の高粘度であっても、ほとんどの被記録材に対して速やかな定着し、耐マーカー性も充分である。また、ヘッド部材への濡れがよくなり、インク組成物気泡排出性の向上、周波数応答性の向上、吐出安定性が格段に向上した。また、請求項２６〜２９に記載の記録液に関する発明の第２の特徴は平均粒径０．５μｍ以下の内部３次元架橋した被記録材と自己分散性顔料に対する吸着力を有する有機超微粒子を用いることである。これにより固定されたヘッドによる高速印字でも顔料が被記録材に定着され乾燥性が早くにじみのない画像が実現できた。
【図面の簡単な説明】
【図１】浸透性測定装置を示す図である。
【図２】インク転移跡を示す図である。
【図３】インクの印字用紙への吸収曲線を示す図である。
【図４】本発明のインクジェット装置の側面図である。
【図５】インク滴付着量（Ｇｍ）を変化させたときの値と、そのベタ画像部の画像濃度値（光学濃度：ＯＤ値）との関係を表わした図である
【図６】インク滴付着量（Ｇｍ）の値を変化させたときの、そのベタ画像部での粒状度との関係を表わした図である。
【図７】単位面積当たりのインク滴付着量（Ｇｍ）の値を変化させたときの、そのベタ画像部での裏抜け濃度との関係を表わした図である。
【符号の説明】
１ 印字装置本体
２ 印字機構部
３ 用紙
４ 給紙カセット（給紙トレイ）
６ 排紙トレイ
１３ キャリッジ
１４ ヘッド
１５ インクカートリッジ
２１ 給紙ローラ
２２ フリクションパッド
２３ ガイド部材
２４ 搬送ローラ
２５ 搬送コロ
２６ 先端コロ
２７ 副走査モータ
３１ 搬送コロ
３２ 拍車
３３ 排紙ローラ
３４ 拍車
３５ ガイド部材
３６ ガイド部材
５１ 印字用インク
５２ インク溜め
５３ 回転ホイール
５４ 印字用紙[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording method for recording information such as characters, images, symbols, etc., particularly on plain paper copier paper (PPC paper) using an ink jet recording apparatus.
[0002]
[Prior art]
Inkjet recording has been known as an excellent recording method regardless of the recording material, and research and development have been actively conducted on a recording apparatus, a recording method, a recording material, and the like.
However, in practice, conventionally, in an ink jet recording apparatus which has been developed and commercialized, an ink jet paper, a special recording material specially developed for ink jet such as a so-called transparency film for ink jet is not used, (1) good fixability; (2) so-called "sharpness"; recorded images free from blurring and bleeding (hereinafter referred to as feathering) in the periphery of characters and images; (3) optical density (Optical Density) : OD), it is difficult to obtain a recorded image with high print quality, and is generally used in office paper such as plain paper copier paper (PPC paper), letter paper, bond paper, postcards, letter paper, envelopes, report paper, etc., and at home. Conventionally used for recording materials such as used paper and generally commercially available transparency film (OHP film) However, when recording was performed with an ink jet recording apparatus as known from the above, the above characteristics could not be satisfied at the same time.
[0003]
Although the above characteristics can be satisfied by using ink-jet paper, ink-jet paper is generally expensive, and ink-jet paper is generally a single-side coated paper. When recording is performed on a non-existing surface, there is a disadvantage that fixability and print quality are remarkably reduced, and this has been one of the causes of the general lack of widespread use of ink jet recording apparatuses.
[0004]
Therefore, (1) excellent fixability, (2) a recorded image of excellent print quality in which blurring and bleeding (hereinafter collectively referred to as feathering) do not occur in the peripheral portion of characters and images, which is so-called "cut", and 3) Various developments have been made to obtain a recorded image having a high optical density (Optical Density: OD).
For example, (1) a strong alkaline ink having a pH of about 13 (see, for example, Patent Documents 1 to 3), and (2) a method of recording by heating a solid wax-like ink at normal temperature and discharging it in a molten state (for example, , Patent Documents 4 and 5), (3) A method of performing recording using an oil-based ink using a water-insoluble organic solvent as a liquid medium has been developed and commercialized.
[0005]
In addition, regarding only the purpose of (1) for obtaining good fixability, (4) an ink containing a large amount of a surfactant (for example, see Patent Document 6), (5) glycerin and N-methyl-2- Pyrrolidone, direct dye and critical micelle concentration 30 dyne.cm^-1Inks (for example, see Patent Document 7) in which the following amounts of low surface tension surfactants are combined (6) Inks in which the pH of the ink is made strongly alkaline and a fluorine-based surfactant is further added (for example, , Patent Documents 3 and 8).
[0006]
However, in the method (1), there is a danger in handling because the ink is strongly alkaline, and printing can be performed with good fixability and good print quality on acidic paper using rosin or the like as a sizing agent. On the other hand, neutral paper using alkyl ketene dimer, stearic anhydride, or the like, whose production has increased in Japan in recent years, shows a significant decrease in fixability and a slight decrease in print quality.
In addition, this strong alkaline ink has a drawback that it is easily penetrated because of a large penetrating power into the inside of the paper, and it is extremely difficult to perform double-sided recording.
[0007]
The method (2) is an excellent method that satisfies the above-mentioned characteristics (1) to (3). However, the printed portion swells, and the print may be transferred if a number of prints are left standing. However, there is a known drawback that the papers are stuck together, and furthermore, there is a problem that a device for heating the ink is required and the apparatus becomes complicated.
[0008]
The method (3) is particularly excellent in fixability, but requires consideration of the odor and safety of the organic solvent contained in the ink. Therefore, the production lot number is printed on the bottom of the can or on the outside of the box. It is used only for industrial purposes such as printing on orifices, and is not in a situation where it is used in ordinary homes.
[0009]
The method (4) using ink has a problem in print quality as disclosed in Patent Document 9 and Patent Document 7, and cannot be said to be an excellent method.
[0010]
In the method using the ink of (5), the drying speed of the ink after printing ("fixing property" in the present invention) is about 8 to 15 seconds as clarified in the embodiment, Although it can be said that the fixing property is better than the known ink, the time of 8 to 15 seconds seems to be long from the standpoint of using the recording device, and depending on the paper, the recording device may not be able to use the recording device. If the printed matter is immediately picked up, the hand may be stained with ink, and feathering may be noticeable depending on the type of paper. Therefore, further improvement is desired.
[0011]
For the ink of (6), the fixing time can be set to 5 seconds or less. The present inventors have confirmed that the ink is excellent in fixability. However, as described in the description of the method (1) above, the ink has excellent safety and neutrality on neutral paper. There is a problem in fixability, print quality, and strike-through, which is not preferable.
[0012]
In addition, in general, it is desirable to use water-based ink in consideration of odor, safety, ink handling properties, and the like, in consideration of office use and general home use. If the recording material is stained with fingerprints or the like, feathering tends to occur only in that part, and the printing quality may change significantly on the front and back of the paper depending on the paper. However, there is also a problem that when the ink is set in the ink jet recording apparatus, great care must be taken in handling the recording material.
[0013]
Further, as is well known in the art, it contains 1 to 5% by weight of a water-soluble dye and 20 to 50% by weight of a water-soluble organic solvent such as glycols, and has a surface tension of about 40 to 55 dyne / cm. In a multi-nozzle ink jet recording apparatus using a water-based ink, the nozzles that do not perform printing (not used for printing) may be clogged even during printing due to evaporation of water from the nozzles. For example, if "-" is repeatedly printed for about 120 seconds and then "1" is printed, the nozzle used when printing "-" normally discharges, but the other nozzles do not discharge. In some cases, such a problem may occur that "1" cannot be correctly printed.
[0014]
Also, if the recording apparatus is left for a while after printing (for example, about two days and nights assuming weekends and holidays), a non-ejection phenomenon that is considered to be caused by an increase in ink viscosity due to evaporation of water from nozzles is often observed. Since it is necessary to perform an operation for solving the non-ejection phenomenon each time the printing apparatus is started to be used, it is often said that the inkjet printing apparatus is difficult to use. Such troubles are relatively common when using a recording device that uses a relatively small amount of energy to fly ink.The foam ejection type recording device discharges more than an ink jet recording device using a piezo element. Because of low energy, it is often seen especially in a foaming jet recording apparatus, and various improvement measures have been devised.
[0015]
In order to prevent the above troubles, it is necessary to incorporate various recovery devices such as caps and pumps into the recording apparatus, which is one of the causes of making the ink jet recording apparatus complicated and expensive.
Also, in recent years, in order to improve the problems with the dye-based ink when using plain paper, use of a pigment-based ink using an organic pigment or carbon black as a colorant has been studied for plain paper printing, Alternatively, it has been put to practical use. Pigments, unlike dyes, have no solubility in water, and thus are usually used as aqueous inks in a state where the pigment is mixed with a dispersant, subjected to dispersion treatment, and stably dispersed in water. By using pigments, light resistance and water resistance can be improved, but it is difficult to satisfy other image quality characteristics at the same time, especially when high-speed printing on plain paper, high image density, sufficient It is difficult to obtain color developability, color reproducibility, etc., and character bleeding, color boundary bleeding, double-sided printing properties, ink drying properties (fixing properties), cockling, etc. are not sufficiently satisfactory. There is still.
[0016]
In order to solve these problems when printing on plain paper using the pigment-based ink, there are techniques disclosed in Patent Documents 10 and 11. In Patent Document 10, a pigment, a polymer dispersant, and a resin emulsion are contained as an ink, and a solid content per unit area on a recording paper at the time of 100% duty printing is adjusted to an appropriate range, thereby making the pigment ink unique. Discloses an ink jet recording method capable of reducing print unevenness due to pigment aggregation regardless of the paper type, eliminating print bleeding, and obtaining an image with high print density. Further, in the above-mentioned Patent Document 11, an ink composition containing a pigment having a dispersing group on the surface of a pigment and having been subjected to a surface treatment so as to be dispersible alone in an aqueous solvent, and an ink containing a penetrating agent are used. By controlling the amount of ink composition discharged per unit area to prevent irregular bleeding of the printed image, the dried ink composition is dried quickly on the recording medium, and high print density is secured. And an ink jet recording method capable of obtaining a good printed image.
[0017]
On the other hand, there are Patent Documents 12, 13, 13 and 14 for the purpose of solving the problems that occur in plain paper printing with the pigment-based ink as described above using an ink configuration.
[0018]
[Patent Document 1]
JP-A-56-57862 (Claim 2 of line 8 to line 10 in the lower left column of page 1)
[Patent Document 2]
JP-A-57-102970 (Claim 1 in the lower left column of the first page, lines 4 to 7)
[Patent Document 3]
JP-A-57-102971 (page 3, upper left column, second line to sixth line)
[Patent Document 4]
JP-A-61-159470 (Claim 1)
[Patent Document 5]
JP-A-62-48774 (Claim 1 in the fifth line to the eighth line in the lower left column on page 1)
[Patent Document 6]
JP-A-55-29546 (Claim 1)
[Patent Document 7]
JP-A-56-49771 (Claims in the lower left column of the first page, lines 3 to 11)
[Patent Document 8]
JP-A-56-57862 (Claims)
[Patent Document 9]
JP-A-55-80477
[Patent Document 10]
JP-A-6-171072 (Claim 1 on page 2, column 1, line 2 to line 6)
[Patent Document 11]
JP-A-2000-355159 (Claims 1 to 3 on page 2, column 1, line 2 to line 19)
[Patent Document 12]
Japanese Patent Application No. 2001-290051
[Patent Document 13]
Japanese Patent Application No. 2002-156317
[Patent Document 14]
Japanese Patent Application No. 2001-286320
[0019]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide an ink-jet recording method in which ink droplets are ejected from a fixed head such as a line head by thermal energy or mechanical energy as fine droplets and adhere to a recording material to perform recording. An object of the present invention is to provide an ink jet recording method and an ink composition which, while being an ink, hardly cause cockling and can provide high quality image quality comparable to a laser printer on plain paper.
In particular,
(1) The recording surface is not selected (it is hardly affected by the surface properties, material, and front and back of paper and film).
(2) High concentration (OD),
(3) The print quality is good and recording with little feathering, color bleed, and strikethrough is possible.
(4) The fixing property is extremely good.
(5) Cockling is extremely small even when printing with a fixed head.
{Circle around (6)} Another object of the present invention is to provide an unprecedented excellent ink jet recording method capable of performing normal printing at any time immediately without using a complicated recovery device.
[0020]
Another object of the present invention is to provide an ink jet recording method capable of performing smooth and natural reproduction recording of complicated kanji characters, oblique lines and curved lines with highly safe ink. Still another object of the present invention is to provide an ink jet recording method capable of obtaining a recorded image having good water resistance.
[0021]
Specifically, in the ink jet recording method described in Patent Document 11, the contact angle of the ink used is as high as 70 ° or more with respect to paper such as plain paper, so that the print density is improved. And improvement such as reduction of character blur. However, when an attempt is made to print on recording paper at 100% duty, the solid content per unit area is several tens ng / m2.²The degree is also required, which causes a problem in terms of ink fixing property (drying property). In particular, when high-speed printing is performed by superposing a plurality of sheets, high-speed printing is not suitable because a paper stain problem occurs due to ink transfer between sheets. Also, depending on the type of paper, there is a problem that white stripes or the like of the background of the paper are generated in a solid portion, a character portion, or the like due to a high contact angle at the time of 100% duty printing. Further, at a color boundary portion of a color, the problem of color bleeding is likely to occur between dots printed adjacent to each other due to a high contact angle in a state of a droplet.
[0022]
Further, the ink jet recording method described in Patent Document 12 is advantageous in terms of image quality in terms of ink drying property (fixing property) because a penetrant is used. Is suitable for high-speed printing because the problem of paper contamination due to ink transfer between papers does not occur. However, since a penetrant is used in the ink composition, when printing on plain paper, a character bleeding phenomenon like dye-based ink occurs, and especially in the case of plain paper, even in the depth direction of the paper. Due to the penetration of the ink, the structure of the double-sided printing on plain paper is not suitable due to the ink strike-through phenomenon.
Therefore, any of the above publications discloses an ink jet recording method capable of obtaining high image quality with satisfactory results in high-speed printing on plain paper.
(Structure) is hard to say.
[0023]
Therefore, in the above-mentioned Patent Documents 12, 13, and 14, in order to solve these problems, a pigment, a water-soluble organic solvent, a polyol or glycol ether having 8 or more carbon atoms, By using an ink droplet configuration containing at least water and water, even when printed on plain paper, (1) good color tone (has sufficient color development and color reproducibility), (2) high image density, 3) Clear image quality without feathering or color bleed in characters / images; 4) Image with little ink strike-through which can withstand double-sided printing; 5) High ink drying property suitable for high-speed printing (fixing) (6) Ink composition capable of printing high-quality images that are sufficiently satisfactory with respect to these image characteristics, such as images having high fastness such as light fastness and water fastness. And a printing apparatus has been proposed.
[0024]
However, in the above-mentioned Patent Documents 12, 13, and 14, when printing is performed on plain paper using a novel ink composition, characters and the like are easily read in accordance with the image resolution, and an appropriate image density can be obtained. The amount of ink attached per unit area was not clear.
Also, even in plain paper, depending on the type of paper, it is not possible to fill a solid image portion or the like with ink, and a white streak image of the background of the paper is generated on the image and the image quality is reduced. There is. On the other hand, depending on a certain paper type, blurring of characters and images (feathering phenomenon and color bleeding phenomenon) may be seriously caused, causing a phenomenon of ink strike-through, so that double-sided printing may not be possible. Thus, a method for controlling image quality according to the type of plain paper has not been clarified. Furthermore, since it is not suitable to obtain a fine line with a higher line density, it has not been clarified about the conditions of the amount of ink adhering per unit area which can further improve the line quality.
[0025]
[Means for Solving the Problems]
The above object is achieved by the present invention described below.
That is, the present invention is an ink jet recording method in which ink droplets are ejected from a fixed head as fine droplets by thermal energy or mechanical energy, and the ink droplets are attached to a recording material to perform recording. , Self-dispersible pigment, polyol or glycol ether having 8 or more carbon atoms, anionic or nonionic surfactant, water-soluble organic solvent, organic ultrafine particles having internal three-dimensionally crosslinked three-dimensionally having an average particle diameter of 0.5 μm or less, and at least water. An aqueous ink having a pigment concentration of 8 wt% or more, a surface tension at 25 ° C. of 17 to 35 dyne / cm, and an ink viscosity of 8 to 20 mPa · sec (20 ° C.) under the following printing conditions: To use.
That is, the volume of one ink droplet flying by one electrical signal is 2 to 40 pl (picoliter), the droplet speed is 4 to 20 m / sec, the driving frequency is 3 to 30 KHz, and the recording density is 600 dpi or more. Is an ink jet recording method characterized in that recording is performed under printing conditions of 100% printing density.
[0026]
(Ink characteristics)
1. Surface tension: 17-35 dyn / cm (25 ° C)
2. Ink viscosity: 8 to 20 mPa · sec (20 ° C)
3. Dynamic contact angle one second after contacting the recording material: 20 ° to 80 °
[0027]
(Printing conditions)
1. Drive frequency: 3 to 30 kHz
2. Recording density: 600 dpi or more
3. Droplet volume: 2 to 40 pl
4. Droplet velocity: 4 to 5 m / sec (mechanical energy)
Droplet velocity: 15 to 20 m / sec (thermal energy)
5. Printing density: 100%
[0028]
The first feature of the recording method of the present invention is that the novel ink composition allows the recording material to have an attached amount per unit area of 5 to 40 g / m2.²], A high image density is obtained so that a print density (OD value: 1.6 or more) in which characters and images can be easily viewed irrespective of the image resolution even when printing on plain paper is obtained. It was found that it could be obtained.
[0029]
The second feature of the recording method of the present invention is that the ink droplet has an absorption coefficient of 6 [ml / m2] when the ink droplet is applied to a recording material by the following Bristow method using a novel ink composition.²/ Ms^1/2] And the adhering amount per unit area of the recording material is 15 [g / m²Or an absorption coefficient of 6 [ml / m] when adhered to a recording material.²/ Ms^1/2] And the adhered amount per unit area of the recording material is 10 to 40 [g / m].²], A high image quality is obtained in which no white streak image of the background of the paper occurs in a solid image portion or the like (the solid portion is almost uniformly filled) irrespective of the type of plain paper. Was found.
[0030]
(Test method: Bristow method)
In FIG. 1, an ink reservoir (52) containing 40 μl of an ink for ink jet printing (51) is brought into close contact with the peripheral surface of a rotating wheel (53) and is brought into contact with a printing paper (54) moving at a specific moving speed. By absorbing ink on the printing paper surface through a slit (slit width 1 mm, slit length 17.5 mm) of the ink reservoir, an ink transfer mark shown in FIG. 2 is obtained on the printing paper surface, and ink contact is obtained from the following equation. The time t and the transfer amount V of the ink are obtained.
(Equation 1)
Contact time t (ms) = slit width d (mm) × 1000 / paper moving speed S (mm / sec)
Transfer volume V (ml / m²) = Ink amount Q (μl) × 1000 / (length L (mm) of ink transfer mark × slit length w (mm))
[0031]
Next, the moving speed of the printing paper (54) is changed, and the ink contact time t and the ink transfer amount V at each moving speed are similarly obtained. From the ink contact time t and the ink transfer amount V obtained as described above, t^1/2Is plotted against V, and an absorption curve of the ink onto the printing paper as shown in FIG. 3 is drawn. The time during which the ink absorption curve is parallel to the horizontal axis is the wetting time, and the subsequent ink absorption curves The respective values are obtained using the slope of the as the ink absorption coefficient.
[0032]
A third feature of the recording method of the present invention is that the novel ink composition has an absorption coefficient of 6 [ml / m] when the ink droplets are adhered to a recording material by the above method.²/ Ms^{1 / 2}] And the adhering amount per unit area of the recording material is 15 to 30 [g / m].²Or the absorption coefficient when adhered to a recording material is 6 [ml / m2].²/ Ms^1/2] And the adhered amount per unit area of the recording material is 10 to 20 [g / m].²], It is possible to obtain good image quality with little blurring of characters and images (feathering phenomenon and color bleeding phenomenon) and low strike-through density regardless of the type of plain paper. I found it.
[0033]
A fourth feature of the recording method of the present invention is that, when printing is performed at a print density of 100% with a novel ink configuration, the amount of adhesion per unit area of the recording material is 30 g / m 2.²], It was found that good image quality with a relatively low strike-through density can be obtained irrespective of the type of plain paper.
[0034]
A first feature of the recording liquid of the present invention resides in that a low surface tension aqueous ink having a surface tension at 25 ° C. of 35 dyne / cm or less is used as the ink. The present inventors have studied various means for improving the fixability of a recorded image. As a result, if the surface tension of the ink is adjusted to be 35 dyn / cm or less, most of the recording materials can be used. This is based on the finding that quick fixation is possible. With this fixing property, the marker resistance is also at a level with no problem. Further, by setting the surface tension of the ink to 35 dyn / cm or less, the wettability of the ink to the head member is improved, the frequency response is improved even with a high-viscosity ink of 8 cps (25 ° C.) or more, and the ejection stability is markedly improved. Due to improvement. This low surface tension ink can be achieved by using an alkyl ether, a polyol or glycol ether having 8 or more carbon atoms, and an anionic or nonionic surfactant. Examples of the alkyl ether include various alkyl ethers described in (2) Water-soluble organic solvent described below.
As the polyol or glycol ether having 8 or more carbon atoms, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,2-diethyl-1,3-pentanediol There are three types.
[0035]
The second feature of the recording liquid of the present invention is to use organic ultrafine particles having an internal three-dimensional crosslinkage having an average particle diameter of 0.5 μm or less, having a surface functional group, and having an adsorbing power to a recording material and a self-dispersing pigment. That is. As a result, the pigment was fixed on the recording material even in high-speed printing with the fixed head, and a dry image was obtained quickly and without blurring.
[0036]
A third feature of the present invention is that the printing quality is remarkably improved by using a high-viscosity ink of 8 cps (25 ° C.) or higher. The low-viscosity ink of about 3 cps (25 ° C.) used in conventional inkjet printers has about 70% of water in the ink, but the high-viscosity ink of about 8 cps (25 ° C.) has about 50% or less, The water evaporation rate when the ink droplet lands on the paper surface is increased by 1.5 to 2.0 times. For this reason, the speed at which the pigment of high concentration agglomerates on the paper surface increases, and bleeding (feathering) is reduced.
[0037]
A fourth feature of the present invention is that the pigment concentration in the ink is 8 wt% or more, preferably 10 wt% or more. Increasing the pigment concentration increases the viscosity of the ink, makes it easier for the pigment to agglomerate on the paper surface, improves the image density (OD), and reduces feathering.
[0038]
A fifth feature of the present invention is that 2-methyl-2,4-pentanediol (1,3-butanediol, 1,3-butanediol, and the like) can be used as compared with a conventionally used low-viscosity wetting agent obtained by mixing ethylene glycol (diethylene glycol) and glycerin. 1,6-hexanediol) and glycerin. The use of a high viscosity wetting agent, combined with a high pigment concentration, can achieve a high viscosity ink.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
1. Recording liquid
The ink composition of the present invention is a recording liquid having the following constitution and having an ink viscosity of 8 cps (25 ° C.) or more. As a coloring material for printing, a pigment and a water-soluble organic solvent for dissolving and dispersing the pigment are essential components, and as additives, there are a surfactant, a preservative, and a pH adjuster. The water-soluble organic solvent is preferably a mixture of two or more organic solvents. The reason is considered to be that the viscosity can be adjusted, the characteristics of the respective moisturizing properties are utilized, and the ejection characteristics of the respective heads are utilized.
(1) Pigment (self-dispersible pigment)
(2) Water-soluble organic solvent
(3) Anionic or nonionic surfactant
(4) Polyol or glycol ether having 8 or more carbon atoms
(5) Organic three-dimensionally crosslinked organic ultrafine particles having an average particle size of 0.5 μm or less
(6) Preservative
(7) pH adjuster
(8) Buffer
(9) Antifoaming agent
(10) Pure water
[0040]
Hereinafter, the components of each ink will be described.
(1) Pigment (self-dispersible pigment)
Regarding the pigment used in the present invention, inorganic pigments and organic pigments can be used without any particular limitation. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, and a thermal method can be used. Examples of organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelated azo pigments, etc.) and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments) , Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinoflurone pigments, etc., dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black and the like.
According to a preferred embodiment of the present invention, among these pigments, those having good affinity for water are preferably used. The particle size of the pigment is preferably from 10 to 300 nm, more preferably from 50 to 150 nm, and most preferably from 80 to 120 nm.
The addition amount of the pigment as a coloring agent in the ink is preferably about 8 to 20% by weight, more preferably about 10 to 15% by weight.
[0041]
Specific examples of the pigment preferably used in the invention include the following.
For black color, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, or metal such as copper, iron (CI pigment black 11), and titanium oxide And organic pigments such as aniline black (CI pigment black 1).
Further, for color, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 138, 153, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant Fast Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48: 3 (permanent red 2B (Sr)), 48: 4 (permanent red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (brilliant carmine 6B), 60: 1, 63. : 1, 63: 2, 64: 1, 81 (rhodamine 6G lake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123 , 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, CI. Pigment Violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36 and the like.
Other pigments (for example, carbon) are treated with a resin or the like to treat the surface of the pigment (eg, carbon) with a graft pigment that can be dispersed in water. Processed pigments and the like can be used.
Further, the pigment may be contained in microcapsules so that the pigment can be dispersed in water.
[0042]
(2) Organic solvent
The use of a pyrrolidone derivative, particularly 2-pyrrolidone, as at least one of the water-soluble organic solvents improves the image quality.
The ink of the present invention uses water as a liquid medium. However, in order to obtain desired physical properties of the ink, to prevent the ink from drying (moisturizing property), and to improve the dissolution stability. For this purpose, for example, the following water-soluble organic solvents are used. These water-soluble organic solvents may be used as a mixture of two or more.
[0043]
Specific examples of the water-soluble organic solvent and the wetting agent include the following.
Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, Polyhydric alcohols such as 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol and petriol;
Polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether;
Polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether;
Nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone;
Amides such as formamide, N-methylformamide, N, N-dimethylformamide;
Amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine;
Sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol;
Propylene carbonate, ethylene carbonate and the like.
[0044]
Among these organic solvents, in particular, diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petriol, and 1,5-pentane Diol, 2-pyrrolidone and N-methyl-2-pyrrolidone are preferred. These have an excellent effect on the solubility and the prevention of jetting characteristics failure due to water evaporation.
[0045]
As other humectants, those containing sugar are preferred. Examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, Lactose, sucrose, trehalose, maltotriose and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include substances widely existing in nature such as α-cyclodextrin and cellulose.
[0046]
Examples of the derivatives of these saccharides include reducing sugars of the aforementioned saccharides (eg, sugar alcohols (general formula HOCH)₂(CHOH) nCH₂OH (where n represents an integer of 2 to 5). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thioacids and the like. Particularly, sugar alcohols are preferable, and specific examples include maltitol and sorbitol.
The content of these saccharides is appropriately in the range of 0.1 to 40% by weight, preferably 0.5 to 30% by weight of the ink composition.
[0047]
(3) Anionic or nonionic surfactant
Although the surfactant is not particularly limited, examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzenesulfonate, laurylate, and salts of polyoxyethylene alkyl ether sulfate.
Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide. No. The surfactants may be used alone or in combination of two or more.
[0048]
The surface tension in the present invention is an index indicating permeability to paper, particularly indicates a dynamic surface tension in a short time of 1 second or less after the surface is formed, and is different from a static surface tension measured in a saturation time. . As a measuring method, any method that can measure a dynamic surface tension of 1 second or less by a conventionally known method described in JP-A-63-31237 or the like can be used, but in the present invention, a Wilhelmy type suspension is used. It measured using the plate type surface tensiometer. The value of surface tension is 40 mJ / m²The following is preferable, and 35 mJ / m is more preferable.²When the content is set as below, excellent fixability and drying property can be obtained.
[0049]
(4) Polyol or glycol ether having 8 or more carbon atoms
The polyol or glycol ether having 8 or more carbon atoms used in the present invention is a partially water-soluble polyol and / or glycol ether having a solubility of less than 0.1 to less than 4.5% by weight in water at 25 ° C. By adding 0.1 to 10.0% by weight based on the total weight of the liquid, the wettability of the ink to the thermal element is improved, and the ejection stability and the frequency stability can be obtained even with a small amount of addition. Do you get it. (1) 2-ethyl-1,3-hexanediol solubility: 4.2% (20 ° C.), (2) 2,2,4-trimethyl-1,3-pentanediol solubility: 2.0% (25 ° C.) )
Penetrants having a solubility between 0.1 and less than 4.5% by weight in water at 25 ° C. have the advantage of having a very high permeability instead of a low solubility. Therefore, a combination of a penetrant having a solubility of less than 0.1 to less than 4.5% by weight in water at 25 ° C. and another solvent or a combination of another surfactant makes it possible to obtain a highly penetrable ink. It can be created.
[0050]
(5) Organic three-dimensionally crosslinked organic ultrafine particles having an average particle size of 0.5 μm or less
The organic ultrafine particles have a surface functional group introduced therein, and the recording liquid containing the organic fine particles has a feature that the surface functional group has an adsorbing power to the colorant. Further, the recording liquid is characterized in that the surface functional group has an adsorbing power to a medium such as paper. The recording liquid contains the organic ultrafine particles in an amount of 5 to 40% by weight.
The pigment is adsorbed on the surface of the organic ultrafine particles which are uniformly dispersed inside and three-dimensionally crosslinked, and a film is formed on the fibers of the paper while maintaining the dot shape, and dried and fixed.
That is, bleeding, drying property, and fixing property can be improved by the intermolecular force between the organic ultrafine particles and the colorant and the adhesive force of the resin particles to the paper.
It is possible to adjust the hardness / softness of the particles by three-dimensionally crosslinking the organic ultrafine particles according to the degree of crosslinking, and to impart hydrophilicity / hydrophobicity by freely introducing surface functional groups. And the surface charge and the like can be freely controlled.
Also, since the internal three-dimensionally cross-linked, it is difficult for the resin particles to fuse due to interfacial tension during solvent evaporation, the primary film forming power is weak, so that no clogging or aggregation occurs, and Can easily be redispersed in a solvent and dried sufficiently on paper to form a strong film due to the adhesion of the resin to the paper.
If the fixability is insufficient, it is also possible to fix by thermosetting.
[0051]
The organic ultrafine particles used in the present invention are very suitable for synthesis by emulsion polymerization, and the cross-linking of the polymer particles is achieved by copolymerizing a polyfunctional monomer having a plurality of double bonds.
Specifically, a styrene / acrylate (styrene, methyl methacrylate, n-butyl acrylate) resin is preferable. The reason is that the particle diameter, shape, degree of cross-linking, surface functional groups, multilayer structure, etc. can be freely adjusted, and the surfactant used is also of a high molecular type, so that there is little fear of foaming, which is suitable.
If the amount is less than 5% by weight, the bleeding, drying and fixing properties cannot be solved, and if the amount is more than 40% by weight, problems occur in the ejection stability and dispersion stability. For this reason, 5 to 40% by weight is preferable.
[0052]
(Method of synthesizing organic ultrafine particles)
Examples of the organic ultrafine particles used in the present invention include what is known as a polymer fine particle dispersion (polymer latex). Usually, a polymer latex is prepared by a so-called emulsion polymerization method using a vinyl monomer, and is a dispersion of a polymer in an aqueous medium in the form of fine particles.
The structure of the polymer constituting the polymer latex can be a homopolymer of any monomer selected from the group of monomers shown below as typical examples or a copolymer of any combination thereof. The usable monomer unit is not particularly limited, and any unit can be used as long as it can be polymerized by a usual radical polymerization method.
[0053]
Monomer group
(A) Olefins: ethylene, propylene, isoprene, butadiene, vinyl chloride, vinylidene chloride, 6-hydroxy-1-hexene, cyclopentadiene, 4-pentenoic acid, methyl 8-nonenoate, vinyl sulfonic acid, trimethylvinylsilane, trimethyl Methoxyvinylsilane, butadiene, pentadiene, isoprene, 1,4-divinylcyclohexane, 1,2,5-trivinylcyclohexane and the like.
(B) α, β-unsaturated carboxylic acids and salts thereof: acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, potassium itaconate and the like.
(C) Derivatives of α, β-unsaturated carboxylic acids: alkyl acrylates (eg, methyl acrylate, ethyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-dodecyl acrylate, etc.), substituted alkyl acrylates (eg, , 2-chloroethyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, allyl acrylate, etc.), alkyl methacrylate (eg, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, etc.), substituted alkyl methacrylate (eg, , 2-hydroxyethyl methacrylate, glycidyl methacrylate, glycerin monomethacrylate, 2-acetoxyethyl methacrylate Acrylate, tetrahydrofurfuryl methacrylate, 2-methoxyethyl methacrylate, ω-methoxypolyethylene glycol methacrylate (polyoxyethylene addition moles = 2 to 100), polyethylene glycol monomethacrylate (polyoxyethylene addition moles = 2 to 100), polypropylene glycol monomethacrylate (additional mole number of polyoxypropylene = 2 to 100), 2-carboxyethyl methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl methacrylate, 3-trimethoxysilylpropyl Methacrylates, allyl methacrylates, etc.), derivatives of unsaturated dicarboxylic acids (eg, monobutyl maleate, dimethyl maleate, monomeric itaconic acid) , Dibutyl itaconate, etc.), polyfunctional esters (eg, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylol) Ethane triacrylate, dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate, 1,2,4-cyclohexanetetramethacrylate, etc.).
(D) Amides of α, β-unsaturated carboxylic acids: for example, acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-methyl-N-hydroxyethylacrylamide, N-tertbutylacrylamide, N -Tert-octylmethacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, N-acryloylmorpholine, diacetoneacrylamide, itaconic acid diamide, N-methylmaleimide, 2-acrylamide- 2-methylpropanesulfonic acid, methylenebisacrylamide, dimethacryloylpiperazine and the like.
(E) Styrene and derivatives thereof: styrene, vinyltoluene, p-tert-butylstyrene, vinylbenzoic acid, methyl vinylbenzoate, α-methylstyrene, p-chloromethylstyrene, vinylnaphthalene, p-hydroxymethylstyrene, p -Styrenesulfonic acid sodium salt, p-styrenesulfinic acid potassium salt, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester and the like.
(F) Vinyl ethers: methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether and the like.
(G) Vinyl esters: vinyl acetate, vinyl propionate, vinyl benzoate, vinyl salicylate and vinyl chloroacetate.
(H) Other polymerizable monomers: N-vinylpyrrolidone, 2-vinyloxazoline, 2-isopropenyloxazoline, divinylsulfone, and the like.
[0054]
The polymer selected preferably in the latex synthesized by copolymerization of these monomers is mainly composed of a homopolymer or a copolymer such as an acrylic / methacrylic resin, a styrene resin, a conjugated diene resin, a vinyl acetate resin, and a polyolefin resin. Among them, polymers having an ethylenically unsaturated group in the main chain or side chain, that is, having conjugated dienes or at least two non-conjugated ethylenically unsaturated groups, It is more preferable that the polymer has at least one monomer having different polymerizability as a constituent monomer component, and a polymer containing conjugated dienes as a constituent component is particularly preferable.
[0055]
Monomers having at least two types of non-conjugated ethylenically unsaturated groups which are the above-mentioned preferred monomers and having different polymerizabilities of the unsaturated groups include allyl acrylate, allyl methacrylate, N-allyl acrylamide, N-allyl Methacrylamide and the like can be mentioned. Specific examples of the conjugated diene monomer which is a particularly preferred monomer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, and 2-n-propyl-1,3-diene. Butadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl -1,3-butadiene, 2-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 1-chlorobutadiene, 2-fluoro-1,3-butadiene, 2,3-dichloro-1, 3-butadiene, 1,1,2-trichloro-1,3-butadiene and 2-cyano-1,3-butadiene, 1,4-hexadiene, cyclopentadiene, ethylidene norbo Runnene and the like can be mentioned.
[0056]
Hereinafter, specific examples of the preferred polymer latex of the present invention are shown in Table 1, but the present invention is not limited thereto. Here, unless otherwise specified, the numerical value indicating the composition ratio of each monomer represents a mass percentage.
[0057]
[Table 1]

[0058]
These polymer latexes may be used alone or in combination of two or more as needed.
The polymer latex synthesized using the emulsion polymerization method has a higher molecular weight and usually has a mass average molecular weight of 100,000 or more, unless a chain transfer agent or the like is used, as compared with ordinary solution polymerization or the like. When a conjugated diene monomer is used or when a monomer having two or more ethylenically unsaturated groups is used, the molecular weight may become substantially infinite due to a crosslinking reaction.
[0059]
The emulsion polymerization method used for synthesizing the polymer latex will be described below. The emulsion polymerization method uses at least one emulsifier in water or a mixed solvent of water and an organic solvent miscible with water (eg, methanol, ethanol, acetone, etc.) in an amount of 5 to 150% by mass based on the dispersion medium. Of the monomers are emulsified using 0.1 to 20% by weight of the emulsifier with respect to the monomers and from 0.02 to 5% by weight of the monomers with the radical polymerization initiator, generally at 30 ° C to about 100%. C., preferably at a temperature of 40.degree. C. to 90.degree. C., with stirring. The amount of the organic solvent miscible with water is 0 to 100%, preferably 0 to 50%, by volume relative to water.
[0060]
Examples of the polymerization initiator include azobis compounds, peroxides, hydroperoxides, redox catalysts, and the like, for example, inorganic peroxides such as potassium persulfate and ammonium persulfate, t-butyl peroctoate, benzoyl peroxide, and isopropyl percarbonate. Organic peroxides such as 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide, 2,2′-azobisisobutyrate and 2,2′-azobiscyanovaleric acid Sodium salt, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] hydrochloride, 2,2′- Azobis {2-methyl-N- [1,1'-bis ( Azo compounds such as (hydroxymethyl) -2-hydroxyethyl] propionamide. Of these, potassium persulfate and ammonium persulfate are particularly preferred.
[0061]
Emulsifiers include water-soluble polymers and the like in addition to anionic, cationic, amphoteric and nonionic surfactants. Specific examples thereof include sodium laurate, sodium dodecyl sulfate, sodium 1-octoxycarbonylmethyl-1-octoxycarbonylmethanesulfonate, sodium laurylnaphthalenesulfonate, sodium laurylbenzenesulfonate, sodium laurylphosphate, cetyl Examples include trimethylammonium chloride, N-2-ethylpyridinium chloride, polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan lauryl ester, polyvinyl alcohol, emulsifiers described in JP-B-53-6190, and water-soluble polymers.
[0062]
In emulsion polymerization, it goes without saying that the polymerization initiator, concentration, polymerization temperature, reaction time, and the like can be widely and easily changed according to the purpose. In addition, the emulsion polymerization reaction may be carried out by putting a monomer, a surfactant, and an aqueous medium in advance in a reaction vessel in full amounts, and adding an initiator, or, if necessary, any of a monomer and an initiator solution, Alternatively, it may be carried out while dropping a part or the whole amount of both. The latex that can be used in the present invention can be easily synthesized by using a usual emulsion polymerization method. The general method of emulsion polymerization is described in detail in the following books. "Synthetic Resin Emulsion (edited by Tadashi Okuda and Hiroshi Inagaki, published by Polymer Publishing Association (1978))", "Application of Synthetic Latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, Published by Polymer Publishing Association (1993)" ) "," Chemistry of Synthetic Latex (Souichi Muroi, published by The Society of Polymer Publishing (1970)) ". In addition, especially what is known as soap-free latex can be preferably used.
[0063]
Another example of the organic ultrafine particles that can be used in the present invention includes a water-insoluble polymer containing a dissociating group. The water-insoluble polymer containing a dissociating group refers to a polymer having an ionic dissociating group. The ionic dissociating group includes a cationic dissociating group such as a tertiary amino group and a quaternary ammonium group, and an anionic dissociating group such as carboxylic acid, sulfonic acid and phosphoric acid. Examples of the dissociative group-containing polymer include a vinyl polymer and a condensation polymer (polyurethane, polyester, polyamide, polyurea, polycarbonate). The water-insoluble polymer having a dissociating group is preferably a polymer having water dispersibility, that is, self-emulsifying property.
[0064]
As the dissociating group contained in the dissociating group-containing vinyl polymer, a carboxyl group, a sulfonic acid group, a monoester sulfate group, -OPO (OH)₂, A sulfinic acid group, or an anionic group such as a salt thereof (for example, an alkali metal salt such as Na or K, or an ammonium salt such as ammonia, dimethylamine, ethanolamine, diethanolamine, triethanolamine, or trimethylamine); Primary, secondary, tertiary amines or salts thereof (eg, salts of organic acids (eg, acetic acid, propionic acid, methanesulfonic acid) and inorganic acids (hydrochloric acid, sulfuric acid, etc.)) and cationic salts such as quaternary ammonium salts Although an anionic group is preferable among them, a carboxyl group is particularly preferable.
[0065]
Examples of the monomer containing the carboxylic acid as a dissociating group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, crotonic acid, and monoalkyl itaconate (for example, monomethyl itaconate, itaconic acid). Monoethyl, monobutyl itaconate, etc.) and monoalkyl maleate (eg, monomethyl maleate, monoethyl maleate, monobutyl maleate, etc.).
[0066]
Examples of the monomer containing the sulfonic acid as a dissociating group include styrene sulfonic acid, vinyl sulfonic acid, acryloyloxyalkyl sulfonic acid (eg, acryloyloxyethyl sulfonic acid, acryloyloxypropyl sulfonic acid, etc.), methacryloyloxyalkyl sulfonic acid (For example, methacryloyloxyethylsulfonic acid, methacryloyloxypropylsulfonic acid, etc.), acrylamidoalkylsulfonic acid (for example, 2-acrylamido-2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-) 2-methylbutanesulfonic acid, etc.), methacrylamide alkylsulfonic acid (for example, 2-methacrylamide-2-methylethanesulfonic acid, 2-methacrylamide) And 2-methylpropane sulfonic acid) and the like.
[0067]
Examples of the monomer containing phosphoric acid as a dissociating group include monoacryloyloxyethyl phosphate and monomethacryloyloxyethyl phosphate.
Among these, acrylic acid, methacrylic acid, styrene sulfonic acid, vinyl sulfonic acid, acrylamide alkyl sulfonic acid and methacrylamide alkyl sulfonic acid are preferable, and acrylic acid, methacrylic acid, styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfone are preferable. The acid, 2-acrylamido-2-methylbutanesulfonic acid, is particularly preferred.
[0068]
Examples of the monomer having a cationic dissociation group include a monomer having a tertiary amino group such as dialkylaminoethyl methacrylate and dialkylaminoethyl acrylate, and N-2-acryloyloxyethyl-N, N, N-. Monomers having a quaternary ammonium group such as trimethylammonium chloride and N-vinylbenzyl-N, N, N-triethylammonium chloride are exemplified.
[0069]
Further, the above-mentioned monomer containing a dissociating group may be copolymerized with a monomer having no dissociating group, and the following monomers can be used as the monomer. That is, acrylic esters, specifically, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl Acrylate, tert-octyl acrylate, 2-chloroethyl acrylate, 2-bromoethyl acrylate, 4-chlorobutyl acrylate, 2-acetoxyethyl acrylate, benzyl acrylate, cyclohexyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 2 -Hydroxyethyl acrylate, 2,2-dimethyl-3-hydroxypropyl acryle G, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, 2- (2-methoxyethoxy) ethyl acrylate, glycidyl acrylate, 1-bromo-2-methoxyethyl acrylate, 2,2,2-tetrafluoroethyl acrylate, 1H, 1H, 2H, 2H-perfluorodecyl acrylate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate And the like.
[0070]
Methacrylic esters, specifically, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-benzyl methacrylate Ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, triethylene glycol monomethacrylate, dipropylene glycol mono Me Acrylate, 2-methoxyethyl methacrylate, 3-methoxybutyl methacrylate, 2-ethoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2- (2-methoxyethoxy) ethyl methacrylate, 2- (2-ethoxyethoxy) ethyl methacrylate, 2- Acetoxyethyl methacrylate, 2-acetoacetoxyethyl methacrylate, allyl methacrylate, glycidyl methacrylate, 2,2,2-tetrafluoroethyl methacrylate, 1H, 1H, 2H, 2H-perfluorodecyl methacrylate, dioctyl-2-methacryloyloxyethyl phosphate, etc. Is mentioned.
[0071]
Vinyl esters, specifically, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate, and the like.
[0072]
Acrylamides, specifically, acrylamide, methylacrylamide, ethylacrylamide, isopropylacrylamide, n-butylacrylamide, tert-butylacrylamide, tert-octylacrylamide, cyclohexylacrylamide, benzylacrylamide, hydroxymethylacrylamide, methoxymethylacrylamide, butoxymethyl Acrylamide, methoxyethyl acrylamide, phenyl acrylamide, dimethyl acrylamide, diethyl acrylamide, β-cyanoethyl acrylamide, N- (2-acetoacetoxyethyl) acrylamide, diacetone acrylamide and the like can be mentioned.
[0073]
Methacrylamides, specifically, methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, n-butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, benzyl methacrylamide, hydroxymethyl methacrylamide, methoxy Ethyl methacrylamide, phenyl methacrylamide, β-cyanoethyl methacrylamide, N- (2-acetoacetoxyethyl) methacrylamide and the like can be mentioned.
[0074]
Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, and 2,3-dimethylbutadiene.
[0075]
Styrenes such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, methyl vinyl benzoate and the like can be mentioned.
[0076]
Vinyl ethers, specifically, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether and the like can be mentioned.
[0077]
Other monomers include butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate, diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl Examples thereof include vinyl ketone, methoxyethyl vinyl ketone, N-vinyl oxazolidone, N-vinyl pyrrolidone, vinylidene chloride, methylene malon nitrile, and vinylidene.
[0078]
It is also preferable to copolymerize a monomer containing a nonionic dispersing group as described below. Examples of such a monomer include an ester of a polyethylene glycol monoalkyl ether and a carboxylic acid monomer, and a polyethylene glycol monoester. Ester of alkyl ether and sulfonic acid monomer, ester of polyethylene glycol monoalkyl ether and phosphoric acid monomer, vinyl group-containing urethane formed from polyethylene glycol monoalkyl ether and isocyanate group-containing monomer, macromonomer containing polyvinyl alcohol structure And the like. The repeating number of the ethyleneoxy moiety of the polyethylene glycol monoalkyl ether is preferably from 8 to 50, and more preferably from 10 to 30. The number of carbon atoms in the alkyl group of the polyethylene glycol monoalkyl ether is preferably from 1 to 20, more preferably from 1 to 12.
[0079]
Next, the above-mentioned condensation group-containing condensation polymer will be described in detail. The dissociative group-containing polyurethane is basically synthesized by a polyaddition reaction using a diol compound and a diisocyanate compound as raw materials.
Specific examples of the diol compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, and 2,2-dimethyl as non-dissociable diols. -1,3-propanediol, 1,4-pentanediol, 2,4-pentanediol, 3,3-dimethyl-1,2-butanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,2-diethyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol , 2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanedi All, 1,2-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol (average Molecular weight = 200-4000), polypropylene glycol (average molecular weight = 200-1000), polyester polyol, 4,4′-dihydroxydiphenyl-2,2-propane, 4,4′-dihydroxyphenylsulfone, and the like.
[0080]
Preferred specific examples of the diisocyanate include ethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-toluene diisocyanate, 1,3-xylylene diisocyanate, 1,5-naphthalene diisocyanate, and m-phenylene. Examples thereof include diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 3,3′-dimethylbiphenylene diisocyanate, dicyclohexylmethane diisocyanate, and methylene bis (4-cyclohexyl isocyanate).
[0081]
The dissociable group-containing polyurethane can be obtained, for example, by using a diol containing a dissociable group at the time of synthesizing the polyurethane. In that case, the dissociating group is introduced into the polyurethane as a substituent from the polymer backbone. Examples of the diol having a dissociating group, particularly an anionic group include 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,5,6-trimethoxy-3,4-dihydroxy Examples include hexanoic acid, 2,3-dihydroxy-4,5-dimethoxypentanoic acid, 3,5-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid, and salts thereof, but are particularly limited to these. Not something.
[0082]
As the dissociating group contained in the dissociating group-containing polyurethane, a carboxyl group, a sulfonic acid group, a sulfuric acid monoester group, -OPO (OH)₂, A sulfinic acid group, or an anionic group such as a salt thereof (for example, an alkali metal salt such as Na or K, or an ammonium salt such as ammonia, dimethylamine, ethanolamine, diethanolamine, triethanolamine, or trimethylamine); Cationic groups such as primary, secondary, tertiary amines and quaternary ammonium salts can be mentioned, among which anionic groups are preferred, and carboxyl groups are particularly preferred.
[0083]
The polyester is basically synthesized by a condensation reaction between a diol compound and a dicarboxylic acid compound. Specific examples of dicarboxylic acid compounds include oxalic acid, malonic acid, succinic acid, glutaric acid, dimethylmalonic acid, adipic acid, pimelic acid, α, α-dimethylsuccinic acid, acetone dicarboxylic acid, sebacic acid, 9-nonanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, phthalic acid, isophthalic acid, terephthalic acid, 2-butylterephthalic acid, tetrachloroterephthalic acid, acetylenedicarboxylic acid, poly (ethylene terephthalate) dicarboxylic acid, Examples thereof include 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, ω-poly (ethylene oxide) dicarboxylic acid, and p-xylylenedicarboxylic acid. These compounds may be used in the form of an alkyl ester of a dicarboxylic acid (for example, dimethyl ester) or an acid chloride of a dicarboxylic acid when conducting a polycondensation reaction with a diol compound, or may be used in the form of maleic anhydride or succinic anhydride. May be used in the form of an acid anhydride such as phthalic anhydride.
[0084]
Dissociative group-containing polyester, other than carboxylic acid, sulfonic acid group, sulfuric acid monoester group, -OPO (OH)₂, A sulfinic acid group, or an anionic group such as a salt thereof (for example, an alkali metal salt such as Na or K, or an ammonium salt such as ammonia, dimethylamine, ethanolamine, diethanolamine, triethanolamine, or trimethylamine); Dissociation such as tertiary amines or salts thereof (eg, salts of organic acids (eg, acetic acid, propionic acid, methanesulfonic acid) and inorganic acids (hydrochloric acid, sulfuric acid, etc.)) and cationic groups such as quaternary ammonium salts It is obtained by synthesis using a dicarboxylic acid compound having a group. The dissociating group other than the carboxylic acid contained in the dissociating group-containing polyester is preferably an anionic group, particularly preferably a sulfonic acid group.
[0085]
Preferred examples of the dicarboxylic acid having a sulfonic acid group and diol raw materials include sulfophthalic acids (3-sulfophthalic acid, 4-sulfophthalic acid, 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, and 2-sulfoterephthalic acid), sulfosuccinic acid Acids, sulfonaphthalenedicarboxylic acids (such as 4-sulfo-1,8-naphthalenedicarboxylic acid, 7-sulfo-1,5-naphthalenedicarboxylic acid), 3,5-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid and These salts can be mentioned.
[0086]
As the diol compound, a compound selected from the same group as the diols described in the above polyurethane can be used. A typical method for synthesizing the polyester is a condensation reaction of the diol compound with a dicarboxylic acid or a derivative thereof, which is obtained by condensing a hydroxycarboxylic acid such as a hydroxycarboxylic acid (for example, 12-hydroxystearic acid). Polyesters obtained by a method such as ring-opening polymerization of cyclic ethers and lactones (Course polymerization reaction theory 6: Ring-opening polymerization (I) by Takeo Saegusa (Kagakudojin, 1971)) are also included in the present invention. It can be suitably used.
[0087]
The polyamide can be obtained by polycondensation of a diamine compound and a dicarboxylic acid compound, polycondensation of an aminocarboxylic acid compound, or ring-opening polymerization of lactams. Examples of the diamine compound include ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, hexamethylenediamine, octamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, piperazine, and 2,5-diamine. Dimethyl piperazine, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, xylylenediamine and the like can be mentioned. Examples of aminocarboxylic acids are glycine, alanine, phenylalanine, ω-aminohexanoic acid, ω-aminodecane Acids, ω-aminoundecanoic acid and anthranilic acid. Examples of the monomer that can be used for ring-opening polymerization include ε-caprolactam, azetidinone, and pyrrolidone. As the dicarboxylic acid compound, a compound selected from the same group as the dicarboxylic acids described in the polyester can be used.
[0088]
The polyurea can be obtained basically by a polyaddition of a diamine compound and a diisocyanate compound or a deammonification reaction of a diamine compound and urea, and the diamine compound as a raw material is the diamines described in the polyamide, and the diisocyanate compound is the polyurethane. Compounds selected from the same group as the described diisocyanates can be used.
[0089]
The polycarbonate can be basically obtained by reacting a diol compound with a phosgene or a carbonate derivative (eg, an aromatic ester such as diphenyl carbonate). Compounds from the same group can be used.
[0090]
The dissociating group can be introduced into each of the polymers by various methods. For example, in the case of polyurethane, as described above, a diol containing a dissociating group can be used during synthesis to be introduced as a substituent from the polymer main chain. Further, as in the case of using a polyester as the water-insoluble polymer, it can be introduced by leaving the unreacted terminal of dicarboxylic acid at the terminal of the polymer. Furthermore, after the polymerization of each polymer, a compound capable of introducing a dissociating group by a reaction such as an acid anhydride (for example, maleic anhydride) can be introduced to a reactive group such as a hydroxy group or an amino group. .
[0091]
For the above-mentioned polymer containing a dissociating group, both the vinyl polymer and the condensed polymer may be used as necessary constituent materials one by one, or may be used for various purposes (for example, adjustment of the glass transition temperature (Tg) of the polymer or solubility of the polymer). , And the compatibility with the dye and the stability of the dispersion).
[0092]
Further, among the dissociative group-containing polymers, those having at least one of a carboxyl group and a sulfonic acid group as the dissociable group are preferable, and those having a carboxyl group as the dissociative group are particularly preferable.
The content of the dissociable group is too small or too small, the self-emulsifying property of the dissociative group-containing polymer is small, and the stabilizing effect of the fine particle dispersion of the dye tends to be small. A preferred range for the content of the dissociable group is 0.1 to 3.0 mmol / g, more preferably 0.2 to 2.0 mmol / g.
[0093]
In addition, the anionic dissociating group as the dissociating group may further be an alkali metal (for example, Na, K or the like) or a salt of an ammonium ion, and the tertiary amine which is the cationic dissociating group. Further, salts of organic acids (eg, acetic acid, propionic acid, methanesulfonic acid) and inorganic acids (eg, hydrochloric acid, sulfuric acid) may be used.
[0094]
Taking into account the excellent dispersing stability imparting and the ease of introducing a dissociating group in the polymer containing a dissociating group, more preferred are vinyl polymers, polyurethanes and polyesters, and particularly preferred is a vinyl polymer.
[0095]
Tables 2 and 3 list specific examples (PP-1) to (PP-54) of the dissociative group-containing vinyl polymer, but the present invention is not limited to these specific examples. The ratio in parentheses means the mass ratio.
[0096]
[Table 2]

[0097]
[Table 3]

[0098]
Table 4 shows specific examples of the condensation polymer (PP-55) to (PP-74) among the dissociative group-containing polymers, but the present invention is not limited thereto. All acidic groups in each polymer are shown in non-dissociated form. Regarding those produced by condensation reaction, such as polyesters and polyamides, the constituent components are all expressed as dicarboxylic acids, diols, diamines, hydroxycarboxylic acids, aminocarboxylic acids and the like irrespective of the raw materials. The ratio in parentheses means the molar percentage ratio of each component.
[0099]
[Table 4]

[0100]
Regarding the synthesis of the above-mentioned condensation polymer containing a dissociating group, "Polymer Experimental Studies (Vol. 5) Polycondensation and Polyaddition (Edited by Shu Kamihara, published by Kyoritsu Shuppan Co., Ltd. (1980))", "Polyester Resin Handbook ( "Eiichiro Takiyama, published by Nikkan Kogyo Shimbun (1988))", "Polyurethane Resin Handbook (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun) (1987)", "Experimental Method for Polymer Synthesis (Takayuki Otsu and Masayoshi Kinoshita) , Published by Kagaku Dojin (1972)), Japanese Patent Publication No. 33-1141, Japanese Patent Publication No. 37-7641, Japanese Patent Publication No. 39-5989, Japanese Patent Publication No. 40-27349, Japanese Patent Publication No. 42-5118, JP-B-42-24194, JP-B-45-10957, JP-B-48-25435, JP-B-49-36942, JP-B-52-81344, JP-A-56-88454, and Kaihei 6 A known method described in each gazette such as -340835 can be used.
[0101]
(Method of synthesizing organic ultrafine particles)
<Synthesis example of organic ultrafine particles [1]>
Organic ultrafine particles are produced by selecting monomers for the core layer and the shell layer such that the difference in refractive index between the core layer and the shell layer is 0.17. The method is described below.
A 1 L flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 ml of distilled water, 0.15 g of potassium persulfate and 1.6 g of Emulgen 913 (manufactured by Kao-Atlas), stirred and mixed in advance. 50 g of styrene, 0.1 g of n-dodecyl mercaptan, and 0.4 g of Levenol WZ (manufactured by Kao-Atlas) are added, and heated to 75 ° C. while purging with nitrogen. Thereafter, polymerization is performed at 75 ° C. for 1 hour. Then, a mixture of 45 g of premixed tridecyl methacrylate, 5 g of methacrylic acid, and 0.1 g of n-dodecyl mercaptan mixed in 15 g of distilled water in which 0.15 g of potassium persulfate was dissolved was taken over 1.5 hours. Drop at a constant rate. Thereafter, the temperature is maintained at 75 ° C. for 5 hours. The obtained emulsion is cooled to room temperature, and the pH is adjusted by adding aqueous ammonia as a neutralizing agent. Further, the solution is filtered through a 0.4 μm filter, and is prepared with distilled water so that the concentration of the polymer fine particles becomes 30%. The glass transition point of the obtained organic ultrafine particles is 12 ° C. Further, the minimum film forming temperature of the polymer emulsion containing the obtained organic ultrafine particles as dispersed particles is around 20 ° C.
[0102]
<Synthesis example of organic ultrafine particles [2]>
The raw materials shown in Table 5 were previously added at the ratios shown in Table 5 by N₂The reactor was charged with a gas-saturated reactor and a dropping tank. The polymerization reaction was started at 55-57 ° C, and when the temperature of the reactor reached 59 ° C, dropping was started. The dropping time was 100 minutes. The polymerization was carried out within a temperature range of 60 to 65 ° C., and the reaction was completed in about 3 hours. Thereafter, the pH was adjusted to 8 to 9 with 25% aqueous ammonia to obtain a water-dispersed resin composition having a solid content of 20%. The average particle size of the obtained water-dispersed resin composition was 120 nm as measured by a laser light scattering method.
[0103]
[Table 5]

[0104]
<Synthesis example of organic ultrafine particles [3] and [4]>
Using the raw materials shown in Table 6, a water-dispersed resin composition having a solid content of 20% was obtained in the same manner as in Synthesis Example [2]. Table 6 shows the progress of polymerization, the presence or absence of aggregates in the obtained aqueous dispersion type resin composition, and the average particle size.
[0105]
[Table 6]

[0106]
<Synthesis example of organic ultrafine particles [5] to [8]>
[5] = A1
[6] = A2
[7] = A3
[8] = A4
<< Polymerization of polyester resin >>
In an autoclave equipped with a thermometer and a stirrer,
156.4 parts by weight of cyclohexanedicarboxylic acid
111.6 parts by weight of ethylene glycol
78.4 parts by weight of tricyclodecane dimethanol
0.1 parts by weight of tetrabutoxy titanate
And heated at 150 to 220 ° C. for 180 minutes to perform an esterification reaction. Next, after the temperature was raised to 240 ° C., the pressure of the system was gradually reduced to 10 mmHg after 30 minutes, and the reaction was continued for 120 minutes. Thereafter, the autoclave was replaced with nitrogen gas, and the pressure was adjusted to atmospheric pressure.
The temperature was maintained at 200 to 220 ° C., 15.4 parts by weight of trimellitic anhydride was added, and the reaction was carried out for 60 minutes to obtain a copolymerized polyester resin (A1). The obtained copolymerized polyester resin has an average molecular weight of 3300 and an acid value of 360 eq. / Ton, the glass transition temperature was 70 ° C. The compositional ratio was as shown in Table 7 by NMR analysis.
[0107]
[Table 7]

[0108]
Thereafter, polymerization was carried out in the same manner as described above except that the raw materials were changed to obtain polyester resins shown in Table 7.
In Table 7,
CHDA: cyclohexanedicarboxylic acid
TPA: Terephthalic acid
IPA: isophthalic acid
SIP: 5-sodium sulfoisophthalic acid
TMA: trimellitic acid
EG: ethylene glycol
NPG: neopentyl glycol
TCDL: tricyclodecane dimethanol
Tg: glass transition temperature
It is.
In the polyester resin (A4), in addition, the content of the sulfur element was determined by fluorescent X-ray analysis and converted to sodium sulfonate group equivalent.
[0109]
It is preferable that a resin emulsion besides the organic ultrafine particles is added to the recording liquid of the present invention. The resin emulsion means an emulsion in which the continuous phase is water and the dispersed phase is the following resin component. Examples of the resin component of the dispersed phase include an acrylic resin, a vinyl acetate resin, a styrene-butadiene resin, a vinyl chloride resin, an acryl-styrene resin, a butadiene resin, and a styrene resin.
[0110]
According to a preferred embodiment of the present invention, the resin is preferably a polymer having both a hydrophilic part and a hydrophobic part. The particle size of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm.
These resin emulsions can be obtained by mixing resin particles with water, optionally with a surfactant.
For example, an emulsion of an acrylic resin or a styrene-acrylic resin is obtained by adding a (meth) acrylate or styrene, a (meth) acrylate, optionally a (meth) acrylate, and a surfactant to water. It can be obtained by mixing. The mixing ratio of the resin component and the surfactant is usually preferably about 10: 1 to 5: 1. When the amount of the surfactant used is less than the above range, it is difficult to form an emulsion, and when the amount exceeds the above range, the water resistance of the ink tends to decrease and the permeability tends to deteriorate.
The ratio of the resin and water as the disperse phase component of the emulsion is suitably from 60 to 400 parts by weight of water, preferably from 100 to 200 parts by weight, per 100 parts by weight of the resin.
[0111]
Commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden Chemical Co., Ltd.) Manufactured by a company).
The ink used in the present invention preferably contains a resin emulsion such that the resin component is 0.1 to 40% by weight of the ink, more preferably 1 to 25% by weight.
The resin emulsion has a property of thickening and aggregating, has an effect of suppressing penetration of a coloring component, and further has an effect of promoting fixation to a recording material. Further, depending on the type of the resin emulsion, a film is formed on the recording material, which has the effect of improving the abrasion resistance of the printed matter.
[0112]
(6) preservative, (7) pH adjuster, (8) buffer, (9) defoamer, (10) pure water
Conventionally known additives can be added to the ink of the present invention in addition to the colorant, the solvent, and the surfactant.
For example, as the preservative and fungicide, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like can be used in the present invention.
As the pH adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the prepared ink.
Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary phosphonium. Examples include hydroxides, carbonates of alkali metals such as lithium carbonate, sodium carbonate, and potassium carbonate.
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.
Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like.
Depending on the purpose, a buffer, an antifoaming agent, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, and the like can be added.
[0113]
2. Inkjet printer
FIG. 4 is an explanatory side view of the printing apparatus having the configuration of the present invention. This ink jet printing apparatus houses a printing mechanism (2) including a print head fixed inside a printing apparatus main body (1), an ink cartridge for supplying ink to the print head, and the like. ), A sheet cassette (or a sheet tray) which can load a larger number of sheets (3) than the front side can be detachably mounted on the lower side of the sheet (3). 3) The manual feed tray for feeding paper manually can be opened, and the paper (3) fed from the paper feed cassette (4) or the manual feed tray is taken in, and required by the printing mechanism (2). After the image is printed, the sheet is discharged from a sheet discharge tray (6) mounted on the rear side.
[0114]
The printing mechanism unit (2) includes a linear head (14) composed of inkjet heads that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) in this order. And mounted with the ink droplet ejection direction facing downward. Each ink cartridge (15) for supplying each color ink to the head (14) is exchangeably mounted.
The ink cartridge (15) has an upper air port communicating with the atmosphere, a lower supply port for supplying ink to the inkjet head, and a porous body filled with ink inside. The ink supplied to the ink jet head by the capillary force is maintained at a slight negative pressure.
[0115]
Further, in this example, the print heads are configured using the heads (14) having the individual configurations for each color, but may be configured as a single head having a nozzle array for discharging ink droplets of each color. Further, as a print head (ink-jet head) (14) for forming ink droplets by pressurizing ink, a liquid chamber wall is formed by an electromechanical transducer such as a piezo element, and a piezoelectric member for pressurizing ink through a diaphragm is provided. A mold or a bubble type in which bubbles are generated in the ink by a heating resistor to pressurize the ink, or the diaphragm is displaced by an electrostatic force between a diaphragm forming an ink flow path wall surface and an electrode opposed thereto. Although an electrostatic type in which ink is pressed can be used, in this configuration example, a case in which a piezoelectric inkjet head is used will be described.
[0116]
In order to transport the paper (3) set in the paper feed cassette (4) to the lower side of the head (14), a paper feed roller (21) that separates and feeds the paper (3) from the paper feed cassette (4). ) And a friction pad (22), a guide member (23) for guiding the paper (3), a transport roller (24) for inverting and transporting the fed paper (3), and the transport roller (24) And a tip roller (26) for defining an angle at which the sheet (3) is sent out from the transport roller (24). The transport roller (24) is driven to rotate by a sub-scanning motor (27) via a gear train. A paper guide is provided for guiding the paper (3) sent from the transport roller (24) to the lower side of the print head (14) in accordance with the movement range of the carriage (13) in the main scanning direction. A printing receiving member, which is a member, is provided. Further, on the downstream side of the printing receiving member in the sheet conveying direction, a conveying roller (31) that is driven to rotate to feed the sheet (3) in the sheet discharging direction, and a spur (32) are provided. ) To the paper discharge tray (6), and a spur (34), and guide members (35) and (36) for securing a paper discharge path. .
[0117]
At a position outside the print area on the right end side in the moving direction of the carriage (13), a recovery processing device for recovering the ejection failure of the head (14) is arranged. The recovery processing device has a cap unit, a suction unit, and a cleaning unit. The carriage (13) is moved to the recovery processing device side during standby for printing, the head (14) is capped by the capping means, and the ejection opening is kept in a wet state to prevent ink ejection failure due to ink drying. it can. In addition, by discharging ink that is not related to printing during printing or the like, the ink viscosity in all the discharge ports becomes constant, and stable discharge performance is maintained. In the event of a discharge failure, for example, the discharge port of the head (14) is sealed with a capping means, air bubbles and the like are sucked out of the discharge port with a suction means through a tube, and ink or dust adhered to the discharge port surface is removed. The ejection failure is removed by the cleaning means and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir (not shown) provided at a lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.
[0118]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. In addition, the amount (%) of each component described in Examples is based on weight.
Pigment surface treatment (method of producing self-dispersing pigment)
The black is carbon black produced by a furnace method or a channel method. The primary particles are 15 nm to 40 nm, and the specific surface area by the BET adsorption method is 50 to 300 m.²/ G, a DBP oil absorption of 40 to 150 ml / 100 g, a volatile matter of 0.5 to 10%, and a pH of 2 to 9 are used. Particularly, acidic carbon black having a pH of 6 or less is preferable at a high concentration. Further, carbon black subjected to hypochlorous oxidation treatment, carbon black treated with a sulfonating agent, and carbon black treated with a diazonium compound to introduce an anionic dissociating group such as sulfonic acid and carboxylic acid are more preferable. As a yellow pigment, a C.I. I Pigment Yellow 74, 128 and 138 are preferred. As the magenta pigment, quinacridone-based C.I. I. Pigment Red 122 and 209 are preferred. Cyan is a phthalocyanine compound. I. Pigment Blue 15: 3, aluminum-coordinated phthalocyanine, and metal-free phthalocyanine are preferred. These color organic pigments are also pigments in which sulfonic acid groups and carboxylic acid groups have been introduced by surface treatment, and are more excellent in dispersion stability, and those capable of obtaining dispersion stability without a dispersant can be suitably used as self-dispersion pigments. . In addition, pigments having encapsulated surfaces or pigments grafted with polymers can also be used as highly reliable inks having excellent dispersion stability.
[0119]
(Reference Example 1) Carbon black 1 treated with hypochlorous acid
After 300 g of commercially available acidic carbon black (pH 2.5, Monarch 1300, manufactured by Cabot Corporation) is well mixed with 1000 ml of water, 450 g of sodium hypochlorite (effective chlorine concentration: 12%) is dropped, and 100 to 105 ° C. For 8 hours. 100 g of sodium hypochlorite (effective chlorine concentration: 12%) was further added to this liquid, and the mixture was dispersed by a horizontal disperser for 3 hours. The obtained slurry was diluted 10-fold with water, pH was adjusted with lithium hydroxide, desalted and concentrated with an ultrafiltration membrane to an electric conductivity of 0.2 mS / cm, and a carbon black dispersion having a pigment concentration of 15% was obtained. And The coarse particles were removed by centrifugation, and the mixture was further filtered through a 1-micron nylon filter to obtain a carbon black dispersion liquid 1. The average particle size (D50%) measured by Microtrac UPA was 95 nm.
[0120]
(Reference Example 2) Carbon black 2 treated with a sulfonating agent
150 g of a commercially available carbon black pigment (“Printex # 85” manufactured by Degussa) was thoroughly mixed in 400 ml of sulfolane, finely dispersed in a bead mill, 15 g of amidosulfuric acid was added, and the mixture was stirred at 140 to 150 ° C. for 10 hours. The obtained slurry is put into 1000 ml of ion-exchanged water, and a surface-treated carbon black wet cake is obtained by a centrifugal separator at 12000 rpm. This carbon black wet cake was redispersed in 2000 ml of ion-exchanged water, the pH was adjusted with lithium hydroxide, and desalted and concentrated by an ultrafiltration membrane to obtain a carbon black dispersion having a pigment concentration of 10% by weight. This was filtered through a 1 micron nylon filter to obtain a carbon black liquid 2. The average particle size was 80 nm.
[0121]
(Reference Example 3) Carbon black dispersion liquid 3 treated with a diazo compound
230m surface area²100 g of carbon black having a DBP oil absorption of 70 ml / 100 g and 34 g of p-amino-N-benzoic acid were mixed and dispersed in 750 g of water, and 16 g of nitric acid was added dropwise thereto, followed by stirring at 70 ° C. Five minutes later, a solution of 11 g of sodium nitrite dissolved in 50 g of water was added, and the mixture was further stirred for 1 hour. The obtained slurry was diluted 10-fold and centrifuged to remove coarse particles, the pH was adjusted to 8 to 9 with diethanolamine, and the mixture was desalted and concentrated with an ultrafiltration membrane to obtain a carbon black dispersion having a pigment concentration of 15%. did. This was used as a carbon black dispersion 3 using a polypropylene 0.5 μm filter. The average particle size was 99 nm.
[0122]
(Reference Example 4) Carbon black dispersion liquid 4 treated with a diazo compound
A solution of about 75 ° C. containing 2 liters of water and 43 g of sulfanilic acid was stirred for 230 m²/ G and 202 ml of carbon black with 70 ml / 100 g DBPA. The mixture was cooled to room temperature with stirring and 26.2 g of concentrated nitric acid was added. A solution of 20.5 g of sodium nitrite in water was added. An internal salt of 4-sulfobenzenediazonium hydroxide was prepared and reacted with carbon black. The dispersion was stirred until the bubbling that had ceased. The obtained slurry was diluted, and the pH was adjusted to 8 to 9 with lithium hydroxide to remove coarse particles by centrifugation. Subsequently, the resultant was desalted and concentrated using an ultrafiltration membrane to disperse carbon black with a pigment concentration of 15%. Liquid. This was filtered through a polypropylene 1 μm filter to obtain a carbon black dispersion liquid 4. The average particle size was 95 nm.
[0123]
(Reference Example 5) Color pigment dispersion liquid subjected to surface chemical treatment
(Yellow dispersion 1, magenta dispersion 1, cyan dispersion 1)
C.I. I. Pigment Yellow 128 was subjected to low-temperature plasma treatment to prepare a pigment into which a carboxylic acid group was introduced. This was dispersed in ion-exchanged water and desalted and concentrated using an ultrafiltration membrane to obtain a yellow pigment dispersion 1 having a pigment concentration of 15%. The average particle size was 70 nm.
Similarly, C.I. I. Pigment magenta 122 was used to prepare a magenta pigment dispersion 1 having a pigment concentration of 15%. The average particle size was 60 nm.
Similarly, C.I. I. Pigment Cyan 15: 3 was used to prepare a cyan pigment dispersion 1 having a pigment concentration of 15%. The average particle size was 80 nm.
[0124]
In the present invention, the use of a surfactant can improve the wettability to recording paper. Preferred surfactants include interfacial polyoxyethylene alkyl ether acetate, dialkyl sulfosuccinate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene block copolymer, and acetylene glycol-based surfactant. Agents. More specifically, polyoxyethylene alkyl ether acetate (I) and / or dialkyl sulfosuccinic acid (II) having a branched alkyl chain having 5 to 7 carbon atoms are used as anionic surfactants. The properties of plain paper are also improved, and the dissolution / dispersion stability of the colorant is selected.
[0125]
Embedded image
R₁-O- (CH₂CH₂O) mCH₂COOM ... (I)
(R₁: An alkyl group having 6 to 14 carbon atoms which may be branched, m: 3 to 12, M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine)
[0126]
Embedded image

(R₂: A branched alkyl group having 5 to 16 carbon atoms, M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine)
[0127]
Embedded image

(R: 6 to 14 carbon chains which may be branched, k: 5 to 20)
[0128]
Embedded image
R- (OCH₂CH₂) NOH (IV)
(R: a carbon chain having 6 to 14 carbon atoms which may be branched, n: 5 to 20)
[0129]
Embedded image

(R ′: carbon chain having 6 to 14 carbon atoms, m, n: m, n ≦ 20)
[0130]
Embedded image

(P, q: 0 to 40)
[0131]
Further, by using lithium ion and quaternary ammonium and quaternary phosphonium represented by the following general formula as counter ions of the surfactant of the present invention, the surfactant exhibits excellent dissolution stability.
Preferred nonionic surfactants include the general formula (III) which is a polyoxyethylene alkylphenyl ether and the general formula (VI) which is an acetylene glycol surfactant. When these are used together, the synergistic effect is further improved in permeability, whereby ink having reduced color boundary bleeding and less character bleeding can be obtained.
The storage stability of the ink can be obtained by setting the pH of the ink to 6 or more. In addition, many copy papers, tags, and the like used in offices have a pH of 5 to 6; The ink is ejected from a fine ejection opening of 9 to 60 μm on paper as a droplet having a weight of 3 ng to 50 ng and flies at 5 to 20 m / s, and the attached amount of a single color is 1.5 g / m.²To 30g / m²It is possible to provide a recording method for forming a high-quality, high-resolution recording image by recording on a so-called plain paper having a degree of Stiggent size of 3 seconds or more according to the JIS P-8122 test method. However, if the pH is 9 or more, the activator of (II) is likely to undergo a change in physical properties due to decomposition during storage, so when (II) is used, the pH is preferably 6 to 9.
[0132]
The amount of the above (I), (II), (III), (IV), (V) and (VI) which can be used in the present invention is required to be 0.05 to 10% by weight depending on the printer system. It is possible to provide the desired permeability to certain ink properties. Here, if it is less than 0.05%, in any case, bleeding occurs at the boundary of the two-color overlapped portion, and when added in an amount of 10% by weight or more, the compound itself may easily precipitate at a low temperature, resulting in poor reliability.
Table 8 below specifically shows the surfactants (I) and (II) used in the present invention in free acid form.
[0133]
[Table 8]

[0134]
The emulsions used in the following examples are emulsions [1] to [8] produced in the synthesis examples of organic ultrafine particles.
Example 1
An ink composition having the following formulation was prepared, and adjusted to a pH of 9 with a 10% aqueous solution of lithium hydroxide. Thereafter, the mixture was filtered with a membrane filter having an average pore diameter of 0.8 μm to obtain an ink composition.
Carbon dispersion 1 8.0 wt%
2-methyl-2,4-pentanediol 22.5wt%
Glycerol 7.5wt%
2-pyrrolidone 5.0 wt%
Activator of specific example (I-1) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [1] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0135]
Example 2
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide.
Carbon dispersion 2 10.0 wt%
1,6-hexanediol 30.0wt%
Glycerol 10.0 wt%
N-methyl-2-pyrrolidone 2.0 wt%
Activator of specific example (I-2) 2.0 wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Emulsion [2] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0136]
Example 3
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide.
Carbon dispersion 3 12.0wt%
Propylene glycol 20.0wt%
Glycerol 10.0 wt%
N-hydroxyethyl-2-pyrrolidone 5.0 wt%
Activator of specific example (I-3) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [3] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0137]
Example 4
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Carbon dispersion 4 10.0 wt%
1,3-butanediol 22.5wt%
Glycerol 7.5wt%
2-pyrrolidone 5.0 wt%
Activator of specific example (I-4) 2.0 wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Emulsion [4] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0138]
Example 5
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Emulsion-coated carbon black dispersion (manufactured by Kao Corporation) 9.0 wt%
2,3-butanediol 22.5wt%
Glycerol 7.5wt%
N-methyl-2-pyrrolidone 3.0 wt%
Activator of specific example (I-5) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0139]
Example 6
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Self-dispersion type carbon black dispersion (Toyo Ink Co., Ltd.) 10.0 wt%
1,4-butanediol 15.0wt%
Glycerol 15.0wt%
N-hydroxyethyl-2-pyrrolidone 5.0 wt%
Activator of specific example (I-6) 2.0 wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Emulsion [5] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0140]
Example 7
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Carboxyl group added type carbon black 13.0wt%
(Cabot Specialty Chemicals, Inc.)
1,3-propanediol 22.5wt%
Glycerol 7.5wt%
2-pyrrolidone 5.0 wt%
Activator of specific example (II-1) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [6] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0141]
Example 8
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Sulfone group addition type carbon black 14.0wt%
(Cabot Specialty Chemicals, Inc.)
2-methyl-2,4-pentanediol 22.5wt%
Glycerol 7.5wt%
N-methyl-2-pyrrolidone 2.0 wt%
Activator of specific example (II-2) 2.0 wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Emulsion [7] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0142]
Example 9
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Carboxyl group added type carbon black 10.0wt%
(Orient Chemical Industries)
1,5-pentanediol 15.0 wt%
Glycerol 15.0wt%
N-hydroxyethyl-2-pyrrolidone 2.0 wt%
Activator of specific example (II-3) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [8] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0143]
Example 10
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Microcapsule inclusion type carbon black 11.0wt%
(Manufactured by Dainippon Ink and Chemicals, Inc.)
1,6-hexanediol 22.5wt%
Glycerol 7.5wt%
3.0% by weight of 2-pyrrolidone
Activator of specific example (II-4) 2.0 wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0144]
Example 11
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide.
Carboxyl group-added self-dispersible carbon black dispersion
(Manufactured by Taisei Kakosha) 8.0 wt%
2-methyl-2,4-pentanediol 22.5wt%
Glycerol 7.5wt%
N-methyl-2-pyrrolidone 5.0 wt%
Activator of specific example (III) (R = C6, k = 5) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [1] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0145]
Color pigment ink
(Cyan pigment ink)
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Cyan dispersion liquid 1 6.0 wt%
Urea 22.5wt%
Glycerol 7.5wt%
N-hydroxyethyl-2-pyrrolidone 5.0 wt%
ECTD-3NEX
(Nikko Chemicals anionic surfactant) 2.0wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [2] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0146]
(Magenta pigment ink)
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Magenta dispersion 1 6.0 wt%
1,3-dimethylimidazolidinone 15.0 wt%
Glycerol 15.0wt%
2-pyrrolidone 5.0 wt%
ECTD-6NEX
(Nikko Chemicals anionic surfactant) 2.0wt%
2,2,4-trimethyl-1,3-pentanediol 2.0 wt%
Emulsion [3] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0147]
(Yellow pigment ink)
An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide.
Yellow dispersion 1 6.0 wt%
Maltose 25.0wt%
Glycerol 15.0wt%
N-methyl-2-pyrrolidone 5.0 wt%
Dispanol TOC
(Nonionic surfactant made by Nippon Oil & Fat) 2.0 wt%
2-ethyl-1,3-hexanediol 2.0 wt%
Emulsion [4] 3.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0148]
Comparative Example 1
An ink composition having the following formulation was prepared, and adjusted to a pH of 9 with a 10% aqueous solution of lithium hydroxide. Thereafter, the mixture was filtered with a membrane filter having an average pore diameter of 0.8 μm to obtain an ink composition.
Polymer dispersant dispersed carbon black
(Manufactured by Dainichi Seika Kogyo) 5.0 wt%
Diethylene glycol 15.0wt%
Glycerol 5.0 wt%
N-methyl-2-pyrrolidone 2.0 wt%
ECTD-6NEX
(Anionic surfactant manufactured by Nikko Chemicals) 1.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0149]
Comparative Example 2
An ink composition was prepared in the same manner as in Comparative Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide.
Surfactant-dispersed carbon black (manufactured by Fuji Dye Corporation) 5.0 wt%
Triethylene glycol 15.0wt%
Glycerol 5.0 wt%
N-hydroxyethyl-2-pyrrolidone 2.0 wt%
Dispanol TOC
(Nonionic surfactant manufactured by NOF Corporation) 1.0 wt%
Emulsion (Microgel solution solid content 20.0% Nippon Paint)
3.0wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0150]
Comparative Example 3
An ink composition was prepared in the same manner as in Comparative Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide.
Polymer dispersant dispersed carbon black (manufactured by Mikuni Dyestuffs Co.) 5.0 wt%
Ethylene glycol 15.0wt%
Glycerol 5.0 wt%
2-pyrrolidone 2.0wt%
ECTD-6NEX
(Anionic surfactant manufactured by Nikko Chemicals) 1.0 wt%
Proxel LV (preservative) 0.2 wt%
Deionized water remaining
[0151]
Table 9 shows the viscosities of Examples 1 to 11, the cyan, magenta, and yellow pigment inks and the ink compositions of Comparative Examples 1 to 3.
[0152]
[Table 9]

[0153]
Next, the following tests were performed and evaluated with respect to Examples 1 to 11 and Comparative Examples 1 to 3 using an inkjet printing apparatus to which the above-described head was fixed.
1) Image sharpness
After printing and drying, the bleeding, image bleeding, color tone, and image density at the boundary of the two-color superposed portion were comprehensively examined by 30 evaluation subjects and a reflection-type color spectral colorimeter (manufactured by X-Rite), and the evaluation described later The judgment was made according to the standard. The printing test paper used is shown below.
▲ 1 ▼ My Paper (NBS Ricoh Co., Ltd.)
(2) Paper source S, recycled paper (NBS Ricoh Co., Ltd.)
(3) PB paper (manufactured by Canon Inc.)
4 Multi Ace (Fuji Xerox Office Supply Co., Ltd.)
5) Yamayuri paper (Honshu Paper Co., Ltd., recycled paper)
6 LH paper (manufactured by Fuji Xerox Office Supply Co., Ltd.)
7) Xerox 4024 paper (manufactured by Fuji Xerox Office Supply Co., Ltd.)
(8) Neenah Bond paper (manufactured by Kimberly-Clark)
[0154]
2) Dryness of image
The filter paper was pressed against the image after printing under certain conditions, and the time until the ink was not transferred to the filter paper was measured. If any of the papers dried within 10 seconds, it was judged as ○.
[0155]
3) Storage stability
Each ink was placed in a polyethylene container and stored at −20 ° C., 5 ° C., 20 ° C., and 70 ° C. for 3 months under the respective conditions, and the surface tension, viscosity, and the presence or absence of precipitate deposition after storage were examined. No change in physical properties and the like was observed regardless of the conditions of storage.
[0156]
4) Reliability during printing suspension
Investigate how much printing can be resumed without capping, cleaning, etc. during operation of the inkjet printing device with the fixed head. The reliability was evaluated based on the change in the weight of the droplet.
[0157]
5) Cockling evaluation
Cockling of each printed sheet immediately after printing was measured with a ruler and evaluated as follows.
：: No cockling occurred.
□: Cockling occurred, but occurred within 5 mm.
Δ: Cockling occurred in a range of 5 mm to 1 cm.
×: Cockling occurred 1 cm or more.
[0158]
[Table 10]

[0159]
(Explanation of claim 1)
FIG. 5 shows an example in which plain paper is used as a print-receiving medium, and ink droplets are formed on the plain paper with the ink of the present invention in a solid image portion (a fixed area of 51.0 [mm] × 149.0 [mm]). The relationship between the value when the ink droplet adhesion amount (Gm) per unit area on paper at that time was changed and the image density value (optical density: OD value) of the solid image portion was experimentally determined. This is the result of the survey.
Here, as a method of measuring the adhesion amount (Gm) of the ink droplet per unit area, the solid image portion is set to an arbitrary image resolution (for example, 720 dpi), and the resolution is set to 100% of printing density (printing rate). In the case of printing, the weight [g] of the ink droplet adhering to the paper is measured with an electronic balance or the like, and the measured weight [g] is used as the print area area [m] of the solid image portion.²] Can be obtained. Regarding the image density (OD value) of the solid image portion, a reflectance spectral densitometer (X-Rite 938 type, manufactured by X-Rite) or the like is used to measure the reflectance of the solid image portion to be printed from the front side of the image. It was measured as a concentration.
By the way, as an image quality, an appropriate optical density (OD) value at which an entire image is easy to see usually requires a value of OD = 1.2 or more in a solid image portion. Therefore, as shown in FIG. 5, for example, using an ordinary paper (trade name: My Paper TA) A manufactured by NBS Ricoh, a value of OD = 1.2 or more, which is an appropriate image density (OD) value, is solid. In the case where the image is to be obtained in the image portion, the value of the ink droplet adhesion amount (Gm) per unit area obtained above is set to 5 [g / m²], The required image density value (OD = 1.2 or more) can be achieved. Further, for example, in the case of using a paper type having a relatively low image density such as a foreign-made plain paper B such as OA paper paper or paper line paper with different paper types, an appropriate image density (OD In order to obtain the value, the value of the ink droplet adhesion amount (Gm) per unit area is set to 10 [g / m²], The required image density value (OD = 1.2 or more) can be achieved.
[0160]
Further, by increasing the ink droplet adhesion amount (Gm) per unit area, the image density (OD) value in the solid image portion is increased to the maximum value OD = 1.7 (in the case of paper type A), or Although it is possible to increase the OD to about 1.5 (in the case of paper type B), the ink droplet adhesion amount (Gm) is 40 [g / m] in any of the paper types (A, B).²In the above range, since the image density (OD) value in the solid image portion is in a saturated state, even if the ink droplet adhesion amount (Gm) is further increased, there is almost no effect of increasing the image density (OD) value. This has been found experimentally.
[0161]
Therefore, in the case of the ink jet printing apparatus of the present invention, when printing on plain paper using the above-described ink of the present invention, the range of the adhesion amount of the ink droplet per unit area is 5 to 40 g. / M²], It is possible to provide an ink jet printing apparatus that can obtain an image density (OD) value that is appropriate as image quality. In the case of the ink jet apparatus of the present invention, in a print head (ink jet head) (14) for pressurizing ink shown in FIG. 4 and discharging ink droplets, a drive signal for driving the head (14) is provided. By providing a means for adjusting the amount of ink ejected from each nozzle of the head (14), the amount of ink adhering per unit area on the printing medium can be adjusted. It becomes possible.
[0162]
In addition, about the measuring method of the advancing contact angle formed between the said paper and an ink droplet, it measures using an automatic contact angle meter by Kyowa Interface Science Co., Ltd. After contacting the amount with the paper, the value of the advancing contact angle formed between the paper and the ink one second after that is shown.
Also, in the measurement of cockling, the range of the adhesion amount of the ink droplet per unit area is set to 5 to 40 g / m 2.²], It was confirmed that cockling hardly occurred.
[0163]
(Explanation of Claims 2 and 4)
In the inkjet printing apparatus of the present invention, an ink containing water, a colorant, a water-soluble organic solvent, a surfactant, and the like can be used, and the type and content of the water-soluble organic solvent and the surfactant can be adjusted. Accordingly, it is possible to obtain an ink having a desired wetting time on a print-receiving medium and an absorption coefficient in the Bristow method. The wetting time and the absorption coefficient of the printing medium in the Bristow method can be determined as follows using the permeability measuring apparatus shown in FIG.
[0164]
<Test conditions>
That is, in FIG. 1, a printing paper (my paper, my paper, etc.) moving at a specific moving speed in close contact with an ink reservoir (52) containing 40 μl of the ink for inkjet printing (51) on the peripheral surface of the rotating wheel (53). (NBS Ricoh Co.) (54), and the ink is absorbed on the printing paper surface through a slit (slit width 1 mm, slit length 17.5 mm) of the ink reservoir to transfer the ink onto the printing paper surface as shown in FIG. After the trace is obtained, the contact time t of the ink and the transfer amount V of the ink are obtained from the following equation.
(Equation 2)
Contact time t (ms) = slit width d (mm) × 1000 / paper moving speed S (mm / sec)
Transfer volume V (ml / m²) = Ink amount Q (μl) × 1000 / (length L (mm) of ink transfer mark × slit length w (mm))
[0165]
Next, the moving speed of the printing paper (54) is changed, and the ink contact time t and the ink transfer amount V at each moving speed are similarly obtained. From the ink contact time t and the ink transfer amount V obtained as described above, t^1/2Is plotted with respect to, and an absorption curve of the ink onto the printing paper as shown in FIG. 3 is drawn. The respective values can be obtained using the slope of the ink as the ink absorption coefficient.
Then, as a result of measuring the ink absorption coefficient in each of the paper types A and B using the ink of the present invention by the Bristow method, the ink absorption coefficient was 8 to 9 [ml / m²/ Ms^1/2], And in the case of paper type B, the ink absorption coefficient is 3 to 4 [ml / m²/ Ms^1/2] Value.
[0166]
Therefore, in FIG. 6, for the paper types A and B having different ink absorption coefficients, the solid image area when the value of the ink droplet adhesion amount (Gm) per unit area in the solid image area is changed. 5 shows the results of an experimental investigation on the relationship with the granularity in the above. Here, the granularity referred to in the present invention refers to a value defined and measured as follows. That is, the printed solid image portion is set as the image portion to be measured, and a measurement image is read from the image portion in the RGB color mode by a scanner device having a resolution of 1000 dpi. Next, the read image data (RGB) is converted into chromaticity (CIE (1976) L).^*a^*b^*) The data is converted to data, the chromaticity data is subjected to Fourier transform, and the Wiener spectrum WS_b(U), WS_c1(U), WS_c2(U) is obtained. WS_b(U) is the lightness component, WS_c1(U), WS_c2(U) represents the Wiener spectrum for the chromaticity component. The Wiener spectrum after the Fourier transform achieves one-dimensional data by averaging in the circumferential direction within a range of 0 to 180 degrees around the origin on the complex plane. Next, what can be expressed by the following equation is defined as the color granularity (CG).
[0167]
(Equation 3)

VTF, which is a visual spatial frequency characteristic, is expressed by the following equation.
(Equation 4)
VTF = 5.05exp (-0.138.ff). (1.0exp (-0.1.ff)
Here, ff means a spatial frequency characteristic on the retina.
h (L^*) Is a correction function for the average brightness, and is represented by the following equation.
[0168]
(Equation 5)

Where t₁= 0.01044, t₂= 0.8978.
Further, P is used as a weighting coefficient in the above equation._{L *}, P_{a *}, P_{b *}Is set to the following value.
P_{L *}= 1.4052
P_{a *}= 1.146
P_{b *}= 0.548
[0169]
Next, using a median filter, an approximate curve is calculated by removing only spike-like spectral components in the power spectrum. Next, only the difference between the power spectrum of the lightness component and the above-mentioned approximation curve, that is, only the spike-like spectrum component is extracted, and the sum thereof is extracted as a texture component (T_X). Finally, each of the above values was substituted into the following equation, defined as “total granularity”, and measured as the granularity for a solid image at each ink adhesion amount value.
Total granularity = α · CG + β · T_X+ Const
(Here, values of α = 0.4157873, β = 3.9060293, const = 0.053109 are set.)
[0170]
In other words, the smaller the value of the “total granularity” is, the smoother and more uniform the solid image (solid image that is uniformly filled with ink droplets) is drawn in the solid image portion.
As a method of measuring the granularity (granularity evaluation scale), ANSI PH-2.40-1985 “root mean square (rms) granularity of film” used in evaluation of silver salt photographs and the like in addition to the above method The method using the “RMS granularity” of the following formula defined by the standard deviation of the density distribution Di specified in the above, and Dooley and Shaw of Xerox, which are widely used in the field of hard copy images (electrophotography, etc.) "Graininess Scale (GS)" defined by the following equation defined by applying the proposed NWS (Noise Wiener Spectrum) to the spatial frequency characteristics of the visual (Visual Transfer Function: VTF) and the value integrated after cascading May be applied, but in the case of an ink jet image, the method using the above “total granularity” is more preferable because the clearest granularity can be obtained.
(Equation 6)
RMS granularity (σ_D) = [1 / NΣ (Di-D)²]^1/2
[0171]
(Equation 7)

(Where u is the spatial frequency, WS_D(U) is a Wiener spectrum, and the term exp (-1.8D) is a function using the average density D obtained by a subjective evaluation experiment as a variable to correct the difference between the density and the brightness perceived by a person. )
[0172]
Therefore, in the result (relational diagram) of FIG. 6, the ink absorption coefficient is large (8 to 9 [ml / m²/ Ms^1/2]) Paper type A and relatively small ink absorption coefficient (3-4 [ml / m²/ Ms^1/2In the case of paper type B, in the range where the value of the ink droplet adhesion amount (Gm) per unit area is relatively small, white streaks and the like in a solid image portion are noticeable, and a desired image is formed by an ink droplet. Since the state is not completely filled with the particles, a rough feeling (granular feeling) is felt. The visual sensation appears as a relatively high value as the value of the “total granularity” as shown in FIG. In addition, by increasing the ink droplet adhesion amount (Gm), in the case of paper type A, 10 to 40 g / m²15 g / m2 for paper type B²By the above, the value of the granularity in the solid image portion can be minimized, and even when the ink of the present invention is used, there is no white stripe in the solid image portion, and the solid image portion is uniformly filled with the desired ink droplets. Images can be obtained. Further, by increasing the ink droplet adhesion amount (Gm), printing unevenness on plain paper appears remarkably for both types of paper (A or B), so that the ink droplet adhesion amount per unit area ( In a range where the value of (Gm) is relatively large, a rough feeling (granularity) is again felt, and the value of the “total granularity” tends to increase as shown in FIG.
[0173]
Therefore, in the case of the ink jet printing apparatus of the present invention, when printing on plain paper of paper types A and B having the respective ink absorption coefficients using the ink of the present invention, the ink absorption of each paper type According to the coefficient, the value of the ink absorption coefficient is 6 [ml / m²/ Ms^1/2], The adhesion amount of the ink droplet per unit area is 10 to 40 [g / m²] Or a value of the ink absorption coefficient of 6 [ml / m²/ Ms^1/2In the following cases, the amount of the ink droplet adhered per unit area is 15 [g / m2].²By adjusting the value to the above value and performing printing, white stripes can be formed in a solid image portion or the like on all types of paper, such as paper that easily absorbs ink (paper type A) and paper that hardly absorbs ink (paper type B). It is possible to provide an ink jet printing apparatus that does not have a proper and stable image quality.
Also, in the measurement of cockling, it was confirmed that cockling hardly occurred by making the range of the amount of the ink droplet adhered per unit area adjustable to this value.
[0174]
(Explanation of Claim 6)
In FIG. 7, plain paper is used as a print-receiving medium, and ink droplets are formed on the plain paper with the ink of the present invention in a solid image portion (a fixed area of 10.0 [mm] × 10.0 [mm]). When the solid image portion is printed at a printing density (printing ratio) of 100%, the value of the ink droplet adhesion amount (Gm) per unit area on paper obtained from the solid image is changed. 5 shows the results of an experimental investigation of the relationship between the density and the strike-through density in the solid image portion. Here, the strike-through density referred to in the present invention refers to a density measured as defined below.
That is, for the solid image portion, the reflectance spectral density (Dr) of the target image from the back side of the paper is measured using a reflection type spectral densitometer (X-Rite 938) manufactured by X-Rite. . Then, after measuring the background density (Dg) of the paper on which the solid image is printed by the same measurement method, the background density (Dg) of the printed paper is calculated from the measured density (Dr) from the back side of the solid image. The density difference (Dr-Dg) thus subtracted was defined as the strike-through density, and the strike-through density at each ink adhesion amount value was measured. In other words, the smaller the strike-through density value, the less the ink show-through on the back side of the paper, and the color is closer to the original background of the paper. The problem of the ink show-through phenomenon has been conspicuously noticeable on plain paper, and in particular, there is a problem that a printed image on the back side of the paper becomes difficult to read when performing double-sided printing on plain paper. .
[0175]
Therefore, it is preferable to experimentally set the appropriate strike-through density value to 0.1 or less, which does not hinder the readability of the printed image on the back side of the plain paper. From the survey results (relational diagram) in FIG. 7, for example, using a normal paper (trade name: My Paper TA) A manufactured by NBS Ricoh, a value of 0.1 or less, which is an appropriate strike-through density value, will be obtained. In this case, the value of the ink droplet adhesion amount (Gm) per unit area is set to about 30 [g / m²], It was found that a value of 0.1 or less, which is an appropriate strike-through density value, can be achieved by setting the value to the following value. Further, for example, when a foreign paper type such as OA paper paper or paper line paper is used due to a different paper type, in order to obtain an appropriate strike-through density value, the per unit area per unit area is required. The value of the ink droplet adhesion amount (Gm) is about 38 [g / m²] The following values can be achieved sufficiently, and about 30 [g / m²], It was experimentally found that ink show-through can be achieved to a level that is hardly noticeable.
[0176]
Therefore, in the case of the ink jet printing apparatus of the present invention, after printing on the front side of plain paper using the ink of the present invention described above, if printing on the back side is desired, the unit of the ink droplet is used. The value of the amount of adhesion per area is about 30 [g / m²By adjusting the value to the following value, a printed image is easy to read even on the back side of plain paper, and an ink jet printing apparatus suitable for double-sided printing can be provided.
[0177]
(Explanation of Claims 3 and 5)
Tables 11 and 12 show “character bleed (feathering)” and “feathering” in character images and color images in addition to the image quality evaluation items (FIGS. 5, 6, and 7) for solid images described above in the present invention. Regarding the image quality evaluation of "color bleed" and the level of "comprehensive image quality evaluation" in consideration of all of the above image quality evaluation items, the value of the amount of ink droplet adhered per unit area to 30 evaluation subjects is sequentially determined. It is a summary of the results of subjective evaluation of each image quality level when changed. The meaning of each symbol in the table is as follows.
[0178]
<Evaluation symbols for "feathering" and "color bleed">
A: The image is easy to see without blurring (appropriate).
□: not blurred, but the image is difficult to see (inappropriate).
Δ: Bleed, but acceptable.
×: Bleeding is unacceptable.
[0179]
<Evaluation symbol for "Comprehensive evaluation">
A: Very good than before.
B: Better than before.
C: Same as before.
D: worse than before.
[0180]
Table 11 shows that the value of the ink absorption coefficient described above as a paper type is 6 [ml / m2].²/ Ms^1/2This is the result of the measurement for paper type A exceeding the above. From the results in Table 11, in the subjective image quality evaluation of 30 evaluation subjects, the optimal range (range where the evaluation symbol is “A”) in which the above-mentioned “comprehensive evaluation” is determined to be an appropriate amount of ink droplets applied is , 10 to 20 g / m²] Was found.
Table 12 shows the results of evaluation performed under the same evaluation conditions as in Table 11, and the value of the ink absorption coefficient described above as a paper type was 6 [ml / m 2].²/ Ms^1/2] The results were obtained for the following paper type B. From the results shown in Table 12, the optimal range in which the amount of ink droplets is determined to be appropriate as the above-mentioned “total image quality evaluation” in the subjective image quality evaluation of 30 evaluation subjects (the range in which the evaluation symbol is “A”) Is 15 to 30 g / m²] Was found.
[0181]
Therefore, in the case of the ink jet printing apparatus of the present invention, when printing on plain paper of paper type A and paper type B having respective ink absorption coefficients using the ink of the present invention described above, Of the ink absorption coefficient is 6 [ml / m²/ Ms^1/2], The ink droplet adhesion amount per unit area of the ink droplet is preferably 10 to 20 g / m2.²] Or a value of the ink absorption coefficient of 6 [ml / m²/ Ms^1/2In the following cases, the amount of the ink droplet adhered per unit area of the ink droplet is preferably 15 to 30 [g / m²] To adjust the value to a value within the range, paper can be easily absorbed by any type of paper (paper type A) or paper that is difficult to absorb (paper type B). High-quality images free of feathering, color bleed, and cockling can be obtained in character images and color images (graphic images), and white streaks also occur in solid images. Accordingly, it is possible to provide an ink jet printing apparatus which can obtain an appropriate print density for characters and images, and has a low strike-through density and stable and high quality image quality.
[0182]
[Table 11]

[0183]
[Table 12]

[0184]
【The invention's effect】
As apparent from the detailed and specific description, according to the first aspect of the present invention, ink droplets fly from the fixed head as fine droplets by thermal energy or mechanical energy and adhere to the recording material. In the ink-jet recording method in which recording is performed by using a recording liquid having a novel ink composition, a print density (OD value: 1.2 or more) that allows characters and images to be sufficiently visible irrespective of image resolution even when printing on plain paper using a recording liquid Therefore, even if high-speed printing is performed, almost no cockling occurs, and an ink jet printing apparatus that can output a clearer and higher-quality color image can be obtained. Provided. According to the second and fourth aspects of the present invention, a high image quality is obtained in which a white stripe image of the background of the paper does not occur in a solid image portion or the like (the solid portion is almost uniformly filled) irrespective of the type of plain paper. As a result, there is provided an ink jet printing apparatus capable of outputting a color image suitable for double-sided printing and high-speed printing with a relatively small amount of ink, with less problems of show-through of characters and images. According to the third and fifth aspects of the present invention, a good image having little blurring of characters and images (feathering phenomenon and color bleeding phenomenon) and cockling and having a low density of strike-through regardless of the type of plain paper. Since the quality can be obtained, there is provided an ink jet printing apparatus capable of outputting a clearer and higher quality color image on plain paper even when printing on both sides and at high speed. According to the sixth aspect, good image quality in which the strike-through density is relatively low can be obtained irrespective of the difference in the type of plain paper, so that the show-through problem of characters and images is reduced. In addition, an ink jet printing apparatus capable of outputting a color image suitable for double-sided printing is provided. In addition, by using the self-dispersing pigment according to claims 8 to 15, it is possible to design a highly reliable pigment ink having excellent resolubility, and provide an ink corresponding to a high-density line head. Is done. The pigment concentration in the ink is set to 8% by weight or more, preferably 10% by weight or more. Increasing the pigment concentration increases the viscosity of the ink, makes it easier for the pigment to agglomerate on the paper surface, improves the image density (OD), and reduces feathering. The recording liquid according to any one of claims 16 to 21 is a high-viscosity ink having a high pigment concentration. However, due to the effect of the selected wetting agent, clogging of the nozzle and cockling are reduced as compared with the conventional high-pigment / high-viscosity ink. And stable printing became possible. Further, the storage stability has been significantly improved. 2-methyl-2,4-pentanediol (1,3-butanediol, 1,6-hexanediol) and glycerin are better than the conventionally used low-viscosity wetting agent obtained by mixing ethylene glycol (diethylene glycol) and glycerin. The use of a high-viscosity wetting agent mixed with The use of a high viscosity wetting agent, combined with a high pigment concentration, can achieve a high viscosity ink. Further, according to claims 22 to 25 of the present invention, the surface tension of the ink becomes 40 dyn / cm or less due to the interaction between the alkyl ether or the polyol having 8 or more carbon atoms and the surfactants (I) to (VI). Even if the concentration is as high as 6 wt% or more and 8.0 cps or more, it is quickly fixed to most recording materials, and the marker resistance is sufficient. In addition, the wetting of the head member was improved, and the ink composition air bubble discharge property, frequency response, and ejection stability were significantly improved. The second feature of the invention relating to the recording liquid according to claims 26 to 29 is that an organic three-dimensionally crosslinked recording material having an average particle diameter of 0.5 μm or less and organic ultrafine particles having an adsorbing power to a self-dispersible pigment are used. It is to use. As a result, the pigment was fixed on the recording material even in high-speed printing with the fixed head, and a dry image was obtained quickly and without blurring.
[Brief description of the drawings]
FIG. 1 is a diagram showing a permeability measuring device.
FIG. 2 is a diagram showing ink transfer marks.
FIG. 3 is a graph showing an absorption curve of ink onto a printing paper.
FIG. 4 is a side view of the ink jet device of the present invention.
FIG. 5 is a diagram illustrating a relationship between a value when an ink droplet adhesion amount (Gm) is changed and an image density value (optical density: OD value) of the solid image portion.
FIG. 6 is a diagram illustrating a relationship between the value of the ink droplet adhesion amount (Gm) and the granularity of the solid image portion when the value is changed.
FIG. 7 is a diagram illustrating the relationship between the value of the ink droplet adhesion amount (Gm) per unit area and the strike-through density in a solid image portion when the value is changed.
[Explanation of symbols]
1 Printer main body
2 Printing mechanism
3 paper
4 Paper cassette (paper tray)
6 Output tray
13 Carriage
14 head
15 Ink cartridge
21 Paper feed roller
22 friction pads
23 Guide member
24 transport rollers
25 Transport rollers
26 Tip roller
27 Sub-scanning motor
31 Transport rollers
32 spurs
33 Paper ejection roller
34 spurs
35 Guide member
36 Guide member
51 Ink for printing
52 Ink reservoir
53 rotating wheel
54 printing paper

Claims (38)

In an ink jet recording method in which ink droplets are ejected from a fixed head as fine droplets by thermal energy or mechanical energy and adhered to a recording material to perform recording, the composition of the ink droplets is a self-dispersible pigment, a water-soluble pigment. An organic solvent, a surfactant, an organic three-dimensionally crosslinked organic ultrafine particle having an average particle size of 0.5 μm or less, and water, and the amount of ink droplets per unit area of the recording material is 5 An ink jet recording method, wherein recording is performed under conditions that fall within a range of from 40 to 40 [g / m ² ]. When the ink droplets are applied to the recording material by the Bristow method, the absorption coefficient is 6 [ml / m ² / ms ^1/2 ] or less, and the adhesion amount per unit area of the recording material is 15 the ink jet recording method according to claim 1, characterized in that the ~40 [g / ^{m 2].} 3. The ink jet recording method according to claim 2, wherein the amount of the recording material per unit area is in a range of 15 to 30 [g / m < ² >]. The absorption coefficient of the ink droplet when adhered to the recording material by the Bristow method exceeds 6 [ml / m ² / ms ^1/2 ], and the amount of adhesion of the recording material per unit area is 10 to 10. the ink jet recording method according to claim 1, characterized in that in the range of 40 [g / m ^2]. 5. The ink jet recording method according to claim 4, wherein the amount of the recording material per unit area is in the range of 10 to 20 [g / m < ² >]. ^2. The ink jet recording method according to claim 1, wherein, when printing is performed at a print density of 100%, the amount of adhesion of the recording material per unit area is 30 [g / m ² ] or less. The ink jet recording method according to any one of claims 1 to 6, wherein an image is formed by adhering to a recording material having a Stigged sizing degree of 3 seconds or more according to JIS P-8122 test method. The recording liquid obtained by the inkjet recording method according to any one of claims 1 to 7, wherein the self-dispersible pigment has a carboxyl group, a sulfone group, a carbonyl group, or a hydroxyl group on the surface. 9. The recording liquid according to claim 8, wherein the surface of the carbon black of the self-dispersion pigment has at least one hydrophilic group by a diazo compound treatment. The recording liquid according to claim 8, wherein at least one kind of hydrophilic group is provided on the surface of the carbon black of the self-dispersion pigment by an oxidation treatment. The recording liquid according to claim 8, wherein the surface of carbon black of the self-dispersion pigment has at least one kind of hydrophilic group by hypochlorous acid treatment. 9. The recording liquid according to claim 8, wherein at least one type of hydrophilic group is provided on the surface of the carbon black of the self-dispersed pigment by a sulfonating agent treatment. 9. The recording liquid according to claim 8, wherein the surface of carbon black of the self-dispersion pigment has at least one hydrophilic group by humic acid treatment. 14. The recording liquid according to claim 8, wherein the self-dispersion pigment has an average particle diameter of 10 nm to 300 nm. 15. The recording liquid according to claim 8, comprising 8 to 20% by weight of the self-dispersing pigment. 16. The recording liquid according to claim 8, comprising 10 to 90 wt% of the water-soluble organic solvent. The recording liquid according to any one of claims 8 to 16, wherein the water-soluble organic solvent comprises a polyol, a lactam, or a urea. The polyols are glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 4-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 1,2,4-butanetriol, 1,2,2 18. The recording liquid according to claim 17, comprising at least one selected from 6-hexanetriol, thiodiglycol, pentaerythritol, trimethylolethane, and trimethylolpropane. The recording according to claim 17, wherein the lactam comprises at least one selected from 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, and ε-caprolactam. liquid. The recording liquid according to claim 17, wherein the urea comprises at least one selected from urea, thiourea, ethylene urea, and 1,3-dimethyl-2-imidazolidinone. The recording liquid according to any one of claims 8 to 20, further comprising a diol or alkyl ether having 6 or more carbon atoms. The anionic surfactant comprises at least one selected from surfactants represented by the following general formulas (I), (II), (III), (IV), (V) and (VI). The recording liquid according to any one of claims 8 to 21.

(R ₁ : alkyl group having 6 to 14 carbon atoms which may be branched, m: 3 to 12, M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine)

(R ₂ : branched alkyl group having 5 to 16 carbon atoms, M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine)

(R: 6 to 14 carbon chains which may be branched, k: 5 to 20)

(R: a carbon chain having 6 to 14 carbon atoms which may be branched, n: 5 to 20)

(R ′: a carbon chain having 6 to 14 carbon atoms, m, n: m, n ≦ 20)

(P, q: 0 to 40) The recording liquid according to any one of claims 8 to 22, further comprising a polyol or glycol ether having 8 or more carbon atoms. The recording liquid according to claim 23, wherein the polyol or glycol ether having 8 or more carbon atoms comprises 2-ethyl-1,3-hexanediol. The recording liquid according to claim 23, wherein the polyol or glycol ether having 8 or more carbon atoms comprises 2,2,4-trimethyl-1,3-pentanediol. The recording liquid according to claim 23, wherein the polyol or glycol ether having 8 or more carbon atoms comprises 2,2-diethyl-1,3-pentanediol. The recording liquid according to any one of claims 8 to 26, comprising 0.1 to 10% by weight of water. The recording liquid according to any one of claims 8 to 27, wherein the organic ultrafine particles have a surface functional group. The recording liquid according to any one of claims 8 to 28, wherein the organic ultrafine particles have an adsorbing power to a recording material. The recording liquid according to any one of claims 8 to 29, wherein the organic ultrafine particles have an adsorbing power for a self-dispersing pigment. 31. The recording liquid according to claim 8, comprising 5 to 40% by weight of the organic ultrafine particles. The recording liquid according to any one of claims 8 to 31, wherein the surface tension is 17 to 35 dyn / cm (25 ° C). The recording liquid according to any one of claims 8 to 32, wherein the ink has a viscosity of 8 to 20 mPa · sec (20 ° C). The recording liquid according to any one of claims 8 to 33, wherein a dynamic contact angle one second after contact with the recording material is 20 ° to 80 °. 35. The recording liquid according to claim 8, wherein the conductivity is 1 mS / cm or more. The recording liquid according to any one of claims 8 to 35, wherein the pH is adjusted to 6 or more and 11 or less. 37. A recording liquid cartridge provided with a recording liquid storage section for storing a recording liquid, wherein the recording liquid is the recording liquid according to any one of claims 8 to 36. An ink jet recording apparatus comprising: a recording liquid storage section or a recording liquid cartridge containing a recording liquid; a head unit or a recording unit for dropping and discharging the recording liquid by the action of thermal energy; A recording apparatus comprising the recording liquid according to any one of Items 8 to 36.

Images