JP2004209762A - Inkjet recording method and curling reduction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curling reduction method by which especially printed matter of plain paper can be easily handled by sufficiently inhibiting the curling. <P>SOLUTION: This inkjet recording method includes a process to discharge ink which contains water, a coloring agent and at least one kind selected between chemical compounds (1) and (2) described below and shows a surface tension of 35m N/m or less to a recording medium by an inkjet recording process. The liquid droplet volume per one liquid droplet of ink is less than 3 pL and the ink implanting amount per unit area is 3×10<SP>-6</SP>mL/mm<SP>2</SP>to 3×10<SP>-5</SP>mL/mm<SP>2</SP>. In addition, data are recorded in the recording medium by performing the specified two or more rounds of main scan through relatively moving a printing head for discharging ink in a main scan direction to a specified region of the recording medium. The chemical compound (1) is a polyhydric alcohol whose molecular weight Mw falls within the range of 100≤Mw≤1,000. The chemical compound (2) is a water-soluble amide compound. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３６】
［上記式中、Ｒはフ水素原子または水酸基で置換された炭素数２〜４の直鎖または分岐鎖状のアルキル基、（ＣＨ_２）ｎＣＯＯＨ（ｎは２または３である。）、（ＣＨ_２）ｎＳＯ_３Ｎａ（ｎは２または３である。）または（ＣＨ_２）ｎＳＯ_３Ｈ（ｎは２または３である。）であり、ｍ及びｎはそれぞれ独立して０〜５の整数を表す。但し、ｍとｎは同時に０とはならない。］；
下記構造式Ａ２で表される水溶性アミド化合物：
【００３７】
【化２】

【００３８】
［上記式中、各ｎ及び各ｍはそれぞれ独立して０〜５の整数を表す。但し、ｍとｎは同時に０とはならない。］；及び
下記構造式Ａ３を有する水溶性アミド化合物：
【００３９】
【化３】

【００４０】
［上記式中、Ｒはフェニレン基、シクロへキシレン基または炭素数２〜４の直鎖のアルキレン基を表し、ｍ及びｎはそれぞれ独立して０〜５の整数を表す。但し、ｍとｎは同時に０とはならない。また、Ｒがフェニレン基、シクロヘキシレン基の場合の、置換位置はオルト、メタ、パラ位（１，２−、１，３−及び１，４−位）のいずれのものであっても良い。］
前記構造式Ａ１におけるＲの水酸基で置換されたアルキル基としては、具体的には−ＣＨ_２ＣＨ_２ＯＨ、−ＣＨ_２ＣＨ_２ＣＨ_２ＯＨ、−ＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２ＯＨ、− （ＣＨ_２）ＣＨ（ＣＨ_３）ＯＨ、−ＣＨ_２ＣＨ_２ＣＨ（ＣＨ_３）ＯＨ、−ＣＨ_２ＣＨ（ＣＨ_３）ＣＨ_２ＯＨ、−ＣＨ（ＯＨ）ＣＨ_２ＣＨ_３、−ＣＨ（ＯＨ）ＣＨ_２ＣＨ_２ＣＨ_３、−ＣＨ_２Ｃ（ＣＨ_３）_２（ＯＨ）、−ＣＨ（ＯＨ）ＣＨ_３、−ＣＨ（ＣＨ_３）ＣＨ_２ＯＨ、−Ｃ（ＣＨ_３）_２ＯＨ、−ＣＨ_２ＣＨ（ＯＨ）ＣＨ_２ＣＨ_３、−ＣＨ（ＣＨ_３）ＣＨ_２ＣＨ_２ＯＨ、−ＣＨ（ＣＨ_３）ＣＨ（ＯＨ）ＣＨ_３、−Ｃ（ＣＨ_３）_２ＣＨ_２ＯＨ、−ＣＨ（ＯＨ）ＣＨ（ＣＨ_３）ＣＨ_３ または −Ｃ（ＯＨ）（ＣＨ_３）ＣＨ_２ＣＨ_３を挙げることができる。
【００４１】
上記、Ａ１〜Ａ３のｍ及びｎとしては各々１または２の場合がより好ましい。また、Ａ３におけるＲがフェニレン基、シクロヘキシレン基の場合の、置換位置はパラ位（１，４−位）のものがより好ましい。さらにまた、分子内においてアミド基が対称的に配置しているＡ２，Ａ３タイプの材料の方がよりカールを効果的に低減できる。
【００４２】
また、分子内においてアミド基が対称的に配置しているＡ２やＡ３タイプの材料の方がよりカールを効果的に低減できる。
【００４３】
前記１）分子量Ｍｗが１００≦Ｍｗ≦１０００の範囲にある多価アルコール、および、２）水溶性アミド化合物の分子量（Ｍｗ）の決定方法を以下に示す。
【００４４】
前記１）の多価アルコールの内、分子量が比較的小さいものＭｗが１００〜１５０のものは下記の方法で測定した。
（１）ＪＩＳハンドブック 化学分析 Ｋ０１１８、Ｋ０１２３に準じ、質量スペクトル測定、（ＧＣ−ＭＳ法、ＬＣ−ＭＳ法から直接求め本発明の分子量とした。
【００４５】
前記１）の多価アルコールの内、分子量が大きいものＭｗが１５０以上のものは下記の方法で測定した。
（２）Ｋ０１２４に準じサイズ排除クロマトグラフ法（ＧＰＣ法）から平均分子量を求め本発明の分子量とした。
【００４６】
分子量分布を有する化合物についてはポリエチレングリコール換算の重量平均分子量を求め、これを本発明の分子量とした。
【００４７】
前記２）の水溶性アミド化合物は下記の方法で測定した。
（３）化合物をＮＭＲ法、赤外分析法、元素分析法などから構造同定を行い、これより分子量を求めこれを本発明の分子量とした。
【００４８】
多価アルコールの分子量に関しては、カール低減効果とインクジェット用インクとして用いる際の信頼性（耐固着性、吐出安定性等）を両立させるために、分子量Ｍｗが１００以上１０００以下が好ましい。また同様に、カール低減効果とインクジェット用インクとして用いる際の信頼性（耐固着性、吐出安定性等）を両立させるために、Ｍｗ１００以上１０００以下の多価アルコールの好適な含有量はインク組成物中に１０〜３０質量％の量であり、より好適には１０質量％から２０質量％である。
【００４９】
上記化合物の好ましい添加量は、分子量Ｍｗが１００以上１０００以下である多価アルコールと上記水溶性アミド化合物の合計でインク中に１０質量％以上２０質量％以下とすることが好ましい。また、多価アルコールと水溶性アミド化合物を併用する場合、多価アルコールの分子量が１００〜１５０のものがより好ましい。
【００５０】
上述した４つの項目、すなわち１ドロップあたりの液滴体積、記録パス数、記録媒体へのインク付着量、インク組成をこれまでの説明の通りに制御することによりインクジェット記録における記録後カールを充分低減することが可能となる。
【００５１】
次に使用するインク組成に関してより詳細な説明を行う。
【００５２】
（着色剤：染料、顔料）
記録するインクの着色剤は水溶性染料、水分散性顔料、およびそれらの組み合わせによって用いられる。着色剤としては、ブラック、シアン、イエロー、マゼンタの他、従来公知のオレンジ、グリーン、ブルーの染料、顔料も問題なく使用できる。
【００５３】
本発明で使用されるインクには、さらにこれに水（水としては種々のイオンを含有する一般の水ではなく、イオン交換水（脱イオン水）を使用するのが好ましい。）、水溶性有機溶媒、及びその他の成分、例えば粘度調整剤、ｐＨ調整剤、防かび剤、界面活性剤、酸化防止剤等が必要に応じて含まれる。
【００５４】
（染料）
本発明において、色を記録する着色剤の染料としては一般にブラック、シアン、マゼンタ、イエローであり、アニオン性の水溶性染料が挙げられる。
【００５５】
本発明で使用されるアニオン性基を有する水溶性染料としては、カラーインデックス（ＣＯＬＯＵＲ ＩＮＤＥＸ）に記載されている水溶性の酸性染料、直接染料、反応性染料であれば特に限定はない。また、カラーインデックスに記載のない染料であっても、アニオン性基、例えばスルホン基を有するものであれば特に制限はない。これらの染料はインク中に１〜１０重量％、好ましくは１〜５重量％の範囲で用いる。具体的な染料としては、
Ｃ．Ｉ．ダイレクトイエロー ８、１１、１２、２７、２８、３３、３９、４４、５０、５８、８５、８６、８７、８８、９８、１００、１１０；
Ｃ．Ｉ．ダイレクトレッド ２、４、９、１１、２０、２３、２４、３１、３９、４６、６２、７５、７９、８０、８３、８９、９５、１９７、２０１、２１８、２２０、２２４、２２５、２２６、２２７、２２８、２３０；
Ｃ．Ｉ．ダイレクトブルー １、１５、２２、２５、４１、７６、７７、８０、８６、９０、９８、１０６、１０８、１２０、１５８、１６３、１６８、１９９、２２６；
Ｃ．Ｉ．アシッドイエロー １、３、７、１１、１７、２３、２５、２９、３６、３８、４０、４２、４４、７６、９８、９９；
Ｃ．Ｉ．アシッドレッド ６、８、９、１３、１４、１８、２６、２７、３２、３５、４２、５１、５２、８０、８３、８７、８９、９２、９４、１０６、１１４、１１５、１３３、１３４、１４５、１５８、１９８、２４９、２６５、２８９；
Ｃ．Ｉ．アシッドブルー １、７、９、１５、２２、２３、２５、２９、４０、４３、５９、６２、７４、７８、８０、９０、１００、１０２、１０４、１１７、１２７、１３８、１５８、１６１；
Ｃ．Ｉ．ダイレクトブラック １７、１９、２２、３１、３２、５１、６２、７１、７４、１１２、１１３、１５４、１６８；
Ｃ．Ｉ．アシッドブラック ２、４８、５１、５２、１１０、１１５、１５６Ｃ．Ｉ．リアクティブブラック １、８、１２、１３；及び
Ｃ．Ｉ．フードブラック １、２
等が挙げられる。勿論以上に限定されるものではない。
【００５６】
また、前記以外に本発明に用いる色を記録するインクの色材として可溶化基として、カルボキシル基を持つ染料が挙げられる。ここでは、ｐＨに対して溶解度の依存性を示す染料が挙げられる。これらの染料はインク中に１〜１０質量％、好ましくは１〜５質量％の範囲で用いる。
【００５７】
（顔料）
次に、本発明において使用される顔料としては、具体的には、黒色のインクに使用されるものとしてカーボンブラックが挙げられる。カーボンブラックとしては、例えば、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あって、一次粒子径が１５〜４０ｍμ、ＢＥＴ法による比表面積が５０〜３００ｍ^２／ｇ、ＤＢＰ吸油量が４０〜１５０ｍ１／１００ｇ、揮発分が０．５〜１０％、ｐＨ値が２〜９等の特性を有するものが好ましく用いられる。この様な特性を有する市販品としては、例えば、Ｎｏ．２３００、Ｎｏ．９００、ＭＣＦ８８、Ｎｏ．３３、Ｎｏ．４０、Ｎｏ．４５、Ｎｏ．５２、ＭＡ７、ＭＡ８、Ｎｏ．２２００Ｂ（以上三菱化成製）、ＲＡＶＥＮ ｌ２５５（以上コロンビア製）、ＲＥＧＡＬ４００Ｒ、ＲＥＧＡＬ ３３０Ｒ、ＲＥＧＡＬ ６６０Ｒ、ＭＯＧＵＬ Ｌ（以上キャボット製）、Ｃｏｌｏｒ Ｂｌａｃｋ ＦＷｌ、ＣＯＬＯＲ ＢｌａｃｋＦＷｌ８、Ｃｏｌｏｒ Ｂｌａｃｋ Ｓｌ７０、Ｃｏｌｏｒ Ｂｌａｃｋ Ｓｌ５０、Ｐｒｉｎｔｅｘ ３５、Ｐｒｉｎｔｅｘ Ｕ（以上デグッサ製）等があり、いずれも好ましく使用することが出来る。
【００５８】
又、イエローインクに使用される顔料としては、例えば、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ ２、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ ３、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ１３、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １６、Ｃ．Ｉ．ＰｉｇｍｅｎｔＹｅｌｌｏｗ７４、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ８３、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １２８等が挙げられる。
【００５９】
マゼンタインクに使用される顔料としては、例えば、Ｃ．Ｉ．ＰｉｇｍｅｎｔＲｅｄ ５、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ７、Ｃ．Ｉ．ＰｉｇｍｅｎｔＲｅｄ ｌ２、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ４８（Ｃａ）、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ４８（Ｍｎ）、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ５７（Ｃａ）、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ｌｌ２、Ｃ．Ｉ．ＰｉｇｍｅｎｔＲｅｄ ｌ２２等が挙げられる。
【００６０】
シアンインクに使用される顔料としては、例えば、Ｃ．Ｉ．ＰｉｇｍｅｎｔＢｌｕｅ １、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ ２、Ｃ．Ｉ．ＰｉｇｍｅｎｔＢｌｕｅ ３、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ ｌ５：３、Ｃ．Ｉ．Ｐｌｇｍｅｎｔ Ｂｌｕｅ ｌ６、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ ２２、Ｃ．Ｉ．Ｖａｔ Ｂｌｕｅ ４、Ｃ．Ｉ．Ｖａｔ Ｂｌｕｅ ６等が挙げられる。
【００６１】
用いる顔料は、これらに限られるものではない。又、以上の他、本発明の為に新たに製造された顔料も勿論、使用することが可能である。
【００６２】
本発明で使用されるインクの色材として顔料が用いられている場合には、顔料の量は、インク全重量に対して、質量比で１〜２０質量％、好ましくは２〜１２質量％の範囲で用いる。
【００６３】
又、顔料を使用する場合に、顔料をインク中に含有させる分散剤としては、水溶性樹脂であればどの様なものでも使用することが出来るが、重量平均分子量が１，０００〜３０，０００の範囲のものが好ましく、更には、３，０００〜１５，０００の範囲のものが好ましく使用される。この様な分散剤として、具体的には、スチレン、スチレン誘導体、ビニルナフタレン、ビニルナフタレン誘導体、α，β−エチレン性不飽和カルボン酸の脂肪族アルコールエステル等、アクリル酸、アクリル酸誘導体、マレイン酸、マレイン酸誘導体、イタコン酸、イタコン酸誘導体、フマール酸、フマール酸誘導体、酢酸ビニル、ビニルピロリドン、アクリルアミド、及びその誘導体等から選ばれた少なくとも２つ以上の単量体（このうち少なくとも１つは親水性単量体）からなるブロック共重合体、或いはランダム共重合体、グラフト共重合体又はこれらの塩等が挙げられる。或いは、ロジン、シェラック、デンプン等の天然樹脂も好ましく使用することが出来る。これらの樹脂は、塩基を溶解させた水溶液に可溶であり、アルカリ可溶型樹脂である。尚、これらの顔料分散剤として用いられる水溶性樹脂は、インク全重量に対して０．１〜５質量％の範囲で含有させるのが好ましい。
【００６４】
特に、上記した様な顔料が含有されているインクの場合には、インク全体が中性又はアルカリ性に調整されていることが好ましい。この様なものとすれば、顔料分散剤として使用される水溶性樹脂の溶解性を向上させ、長期保存性に一層優れたインクとすることが出来るので好ましい。但し、この場合、インクジェット記録装置に使われている種々の部材の腐食の原因となる場合があるので、好ましくは、７〜１０のｐＨ範囲とするのが望ましい。
【００６５】
この際に使用されるｐＨ調整剤としては、例えば、ジエタノールアミン、トリエタノールアミン等の各種有機アミン、水酸化ナトリウム、水酸化リチウム、水酸化カリウム等アルカリ金属水酸化物等に代表される無機アルカリ剤のほか、有機酸や鉱酸等が挙げられる。上記した様な顔料及び分散剤である水溶性樹脂は、水性液媒体中に分散又は溶解される。
【００６６】
上記した様な顔料が含有されたインクの作成方法としては、始めに、分散剤としての水溶性樹脂及び水が少なくとも含有された水性媒体に顔料を添加し、撹拌した後、後述の分散手段を用いて分散を行い、必要に応じて遠心分離処理を行って所望の分散液を得る。次に、この分散液にサイズ剤、及び、上記で挙げた様な適宜に選択された添加剤成分を加え、撹拌して本発明で使用するインクとする。
【００６７】
尚、分散剤として前記した様なアルカリ可溶型樹脂を使用する場合には、樹脂を溶解させる為に塩基を添加することが必要であるが、この際の塩基類としては、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、アミンメチルプロパノール、アンモニア等の有機アミン、或いは水酸化カリウム、水酸化ナトリウム等の無機塩基が好ましく使用される。
【００６８】
又、顔料が含有されているインクの作成方法においては、顔料を含む水性媒体を撹拌し分散処理する前に、プレミキシングを３０分間以上行うのが効果的である。即ち、この様なプレミキシング操作は、顔料表面の濡れ性を改善し、顔料表面への分散剤の吸着を促進することが出来る為、好ましい。
【００６９】
上記した顔料の分散処理の際に使用される分散機は、一般に使用される分散機なら、如何なるものでもよいが、例えば、ボールミル、ロールミル及びサンドミル等が挙げられる。その中でも、高速型のサンドミルが好ましく使用され、この様なものとしては、例えば、スーパーミル、サンドグラインダー、ビーズミル、アジテータミル、グレンミル、ダイノーミル、パールミル及びコボルミル（いずれも商品名）等が挙げられる。
【００７０】
又、顔料が含有されているインクをインクジェット記録方法に使用する場合には、耐目詰り性等の要請から、最適な粒度分布を有する顔料が用いられるが、所望の粒度分布を有する顔料を得る方法としては、分散機の粉砕メディアのサイズを小さくすること、粉砕メディアの充填率を大きくすること、処理時間を長くすること、吐出速度を遅くすること、粉砕後フィルターや遠心分離機等で分級すること及びこれらの手法の組合せ等の手法が挙げられる。
【００７１】
また、上述した水溶性染料と水分散性顔料を微妙な調色の目的や色濃度の調整などのために組み合わせることも可能である。このとき、水性染料と水分散性顔料は目的に応じて１０：１〜１：１０の範囲で配合可能である。
【００７２】
本発明における記録インクの物性として好適な範囲は２５℃付近で、ｐＨは３〜１２、好ましくは７〜１０、表面張力は１０〜６０ｍＮ／ｍ、好ましくは１０〜４０ｍＮ／ｍであり、粘度は１〜３０ｍＰａ・ｓ（ｃｐｓ）、好ましくは１〜５ｍＰａ・ｓである。
【００７３】
（水溶性液媒体）
本発明においては着色剤と上述したカール低減剤となる化合物以外に水と混合して使用できる水溶性有機溶剤を適宜配合して用いることが好ましい。
【００７４】
水と混合して使用される水溶性有機溶剤としては、例えば、
（１）メチルアルコール、エチルアルコール、ｎ−プロピルアルコール、イソプロピルアルコール、ｎ−ブチルアルコール、ｓｅｃ−ブチルアルコール、ｔｅｒｔ−ブチルアルコール、イソブチルアルコール、ｎ−ペンタノール等の炭素数１〜５のアルキルアルコール類；
（２）ジメチルホルムアミド、ジメチルアセトアミド等のアミド類；
（３）アセトン、ジアセトンアルコール等のケトン又はケトアルコール類；
（４）テトラヒドロフラン、ジオキサン等のエーテル類；
（５）ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、エチレングリコール、プロピレングリコール、トリメチレングリコール、トリエチレングリコールなど２〜６個の炭素原子を含むアルキレングリコール類；
（６）グリセリン；
（７）エチレングリコールモノメチル（又はエチル）エーテル、ジエチレングリコールモノメチル（又はエチル、ブチル）エーテル、トリエチレングリコールモノメチル（又はエチル、ブチル）エーテル等の低級アルキルエーテル類；
（８）トリエチレングリコールジメチル（又はジエチル）エーテル、テトラエチレングリコールジメチル（又はジエチル）エーテル等の多価アルコールの低級ジアルキルエーテル類；
（９）モノエタノールアミン、ジエタノールアミン、トリエタノールアミン等のアルカノールアミン類；及び
（１０）スルホラン、Ｎ−メチル−２−ピロリドン、２−ピロリドン、１，３−ジメチル−２−イミダゾリジノン等が挙げられる。
【００７５】
上記のごとき水溶性有機溶剤は、単独でも或いは混合物としても使用することができる。
【００７６】
また、使用される水の含有量としては、インク全重量の１０〜９０質量％、好ましくは３０〜８０質量％の範囲とすることができる。
【００７７】
（記録装置について）
図１は、本発明に係る吐出時に気泡を大気と連通する吐出方式の液体吐出ヘッドとしての液体吐出ヘッドおよびこのヘッドを用いる液体吐出装置としてのインクジェットプリンタの一例の要部を示す概略斜視図である。図１においては、インクジェットプリンタは、ケーシング １００８ 内に長手方向に沿って設けられる記録媒体としての用紙 １０２８ を図１に示す矢印Ｐで示す方向に間欠的に搬送する搬送装置 １０３０ と、搬送装置 １０３０ による用紙 １０２８ の搬送方向Ｐに略直交する方向Ｓに略平行に往復運動せしめられる記録部 １０１０ と、記録部 １０１０ を往復運動させる駆動手段としての移動駆動部 １００６ とを含んで構成されている。
【００７８】
搬送装置 １０３０ は、互いに略平行に対向配置される一対のローラユニット １０２２ａ および １０２２ｂ と、一対のローラユニット １０２４ａ および １０２４ｂ と、これらの各ローラユニットを駆動させる駆動部 １０２０ とを備えている。これにより、駆動部 １０２０ が作動状態とされるとき、用紙 １０２８ が図１に示す矢印Ｐ方向にそれぞれのローラユニット １０２２ａ および １０２２ｂ と、ローラユニット １０２４ａ および １０２４ｂ により狭持されて間欠送りで搬送されることとなる。
【００７９】
移動駆動部 １００６ は、所定の間隔をもって対向配置される回転軸に配されるプーリ １０２６ａ および １０２６ｂ に巻きかけられるベルト １０１６ と、ローラユニット １０２２ａ および １０２２ｂ に略平行に配置され記録部 １０１０ のキャリッジ部材 １０１０ａに連結されるベルト １０１６ を順方向および逆方向に駆動させるモータ １０１８ とを含んで構成されている。
【００８０】
モータ １０１８ が作動状態とされてベルト １０１６ が図７の矢印Ｒ方向に回転したとき、記録部 １０１０ のキャリッジ部材 １０１０ａ は図７の矢印Ｓ方向に所定の移動量だけ移動される。また、モータ １０１８ が作動状態とされてベルト １０１６ が図１の矢印Ｒ方向とは逆方向に回転したとき、記録部 １０１０ のキャリッジ部材 １０１０ａは図１の矢印Ｓ方向とは反対の方向に所定の移動量だけ移動されることとなる。さらに、移動駆動部 １００６ の一端部には、キャリッジ部材 １０１０ａ のホームポ ジションとなる位置に、記録部 １０１０ の吐出回復処理を行うための回復ユニット１０２６ が記録部 １０１０ のインク吐出口配列に対向して設けられている。
【００８１】
記録部 １０１０ は、インクジェットカートリッジ（以下、単にカートリッジと記述する場合がある）１０１２Ｙ、１０１２Ｍ、１０１２Ｃおよび １０１２Ｂが各色、例えばイエロー、マゼンタ、シアンおよびブラックごとにそれぞれ、キャリッジ部材 １０１０ａに対して着脱自在に備えられる。
【００８２】
【実施例】
次に、実施例及び比較例を挙げて、本発明を具体的に説明する。本発明は、その要旨を超えない限り、下記実施例により限定されるものではない。尚、文中「部」または「％」とあるのは特に断りのない限り質量基準である。
【００８３】
実施例１〜１８
下記組成のインクを作製した。
（記録インク１の作製）
下記成分を混合し、更にポアサイズが０．２ミクロンのメンブレンフィルターにて加圧濾過し、記録インク１を得た。
Ｃ．Ｉ．ダイレクトブルー１９９：３部
ポリエチレングリコール（ＰＥＧ）−３００：８部
グリセリン：１０部
ジエチレングリコール：８部
アセチレノールＥＨ（川研ファインケミカル製）：１部
イオン交換水：６０部
（記録インク２の作製）
下記成分を混合し、更にポアサイズが０．２ミクロンのメンブレンフィルターにて加圧濾過し、記録インク１を得た。
Ｃ．Ｉ．ダイレクトブルー１９９：３部
ＰＥＧ−３００：１２部
グリセリン：１０部
尿素：８部
アセチレノールＥＨ（川研ファインケミカル製）：１部
イオン交換水：６９部
（記録インク３の作製）
下記成分を混合し、更にポアサイズが０．２ミクロンのメンブレンフィルターにて加圧濾過し、記録インク１を得た。
Ｃ．Ｉ．ダイレクトブルー１９９：３部
ＰＥＧ−２００：１２部
グリセリン：１０部
エチレン尿素：８部
アセチレノールＥＨ（川研ファインケミカル製）：１部
イオン交換水：７８部
（記録インク４の作製）
下記成分を混合し、更にポアサイズが０．２ミクロンのメンブレンフィルターにて加圧濾過し、記録インク１を得た。
Ｃ．Ｉ．ダイレクトブルー１９９：３部
ＰＥＧ−２００：１２部
グリセリン：１０部
ＨＯＨ_２ＣＨ_２Ｃ−ＮＨ−（Ｃ＝Ｏ）ＮＨ−ＣＨ_２ＣＨ_２ＯＨ：８部
アセチレノールＥＨ（川研ファインケミカル製）：１部
イオン交換水：７８部
ここで使用したインクジェト記録装置としては、図１に示したのと同様の記録装置を用いた。用いた記録ヘッドは、１２００ｄｐｉの記録密度を有し、駆動条件としては、駆動周波数１０ｋＨｚとした。
【００８４】
上記記録インク１から４と表１に示す記録条件の組み合せにて記録を行った。記録紙にはキヤノン製インクジェット、電子写真共用紙ＰＢ用紙を使用した。
【００８５】
【表１】

【００８６】
表１における単位は下記の通りである。
液滴体積：ｐｌ
記録パス数（回）
インク付与量：×１０^−５ｍｌ／ｍｍ^２
上記条件で記録した記録物のカール量を以下のようにして評価した。
（カールの評価）
記録物を常温／常湿下でそれぞれ１日間、４日間、７日間放置した後、カール量を測定した。記録物の紙が凹方向にカールした場合を＋（プラスカール）、カールした紙の先端から紙の接地面までの距離を定規で測定した。数値は紙の４すみの平均を求めカール量とした。評価結果を表１に示した。
カール判定基準は以下の通りである。
Ａ…２０ｍｍ未満：全く問題ないレベル
Ｂ…２０ｍｍ以上３５ｍｍ未満：実用上問題ないレベル
Ｃ…３５ｍｍ以上：実用上問題あり
表２に実施例及び比較例のカールの評価結果を示した。
【００８７】
【表２】

【００８８】
表２からわかるように本発明により、普通紙インクジェット記録により記録後カールを低減する方法が示された。
【００８９】
【発明の効果】
以上説明したように、本発明によれば、特に普通紙へのインクジェット記録方法に関して、カールを十分に抑制し、印刷物のハンドリングが大幅に改善される効果が示された。
【図面の簡単な説明】
【図１】液体吐出ヘッドを搭載可能なインクジェットプリンタの一例の要部を示す概略斜視図である。
【図２】２パス印字を説明する図である。
【図３】４パス印字を説明する図である。
【符号の説明】
１００８ ケーシング
１０１０ 記録部
１０１０ａ キャリッジ部材
１０１２ カートリッジ
１０１２Ｙ，Ｍ，Ｃ，Ｂ インクジェットカートリッジ
１０１６ ベルト
１０１８ モータ
１０２０ 駆動部
１０２２ａ，１０２２ｂ ローラユニット
１０２４ａ，１０２４ｂ ローラユニット
１０２６ 回復ユニット
１０２６ａ，１０２６ｂ プーリ
１０２８ 用紙
１０３０ 搬送装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a post-recording curl reduction method in an ink jet recording method for recording an image by discharging ink.
[0002]
[Prior art]
The ink-jet method is a recording method in which minute droplets of ink are made to fly and adhere to a recording medium (paper, etc.) based on various operating principles to record images, characters, and the like. It is widely used in various applications because it is easy to use, has high flexibility of recording patterns, and does not require development and fixing. Various types of recording media, such as plain paper, coated paper, glossy paper, OHP sheets, and back print films, are commercially available when recording by the ink jet recording method. We often use plain paper. The required characteristics at this time include, while satisfying the above-mentioned characteristics, alleviating and suppressing the curl (curling or curling) phenomenon that occurs when a large amount of ink is applied to the paper. Here, it is important to alleviate and suppress curl during recording as well as curl after recording, which is caused by moisture drying and evaporation after recording.
[0003]
There are various uses of the recorded matter recorded by the ink jet, and the curled paper is rolled up when piled up or filed, and various problems occur because the flatness cannot be maintained. In addition, printing may be performed using low-priced plain paper for an OHP presentation document. At this time, if figures, photographs, and backgrounds are recorded in a secondary color such as blue, the paper may be warped. This often makes handling difficult.
[0004]
Here, the phenomenon of curling is largely due to the provision of moisture. That is, it has been found that when the recording area is large, and when the amount of applied ink at the time of recording is large, the curl is remarkably caused.
[0005]
Conventionally, several methods have been proposed as methods for alleviating and suppressing this curl. For example, Japanese Patent Application Laid-Open No. 4-332775 (Patent Document 1) proposes an inkjet ink having a solid structure that has four or more hydroxyl groups in a molecular structure and is soluble in water or an aqueous organic solvent. In addition, Japanese Patent Application Laid-Open No. 6-157555 (Patent Document 2) proposes an ink containing an anti-curl agent such as a saccharide. JP-A-6-240189 (Patent Document 3) and JP-A-9-165538 (Patent Document 4) propose inks containing saccharides and sugar alcohols. Japanese Patent Application Laid-Open No. 9-176538 (Patent Document 5) proposes an ink containing a specific amide compound as an anti-curl agent. Japanese Patent Application Laid-Open No. Hei 10-130550 (Patent Document 6) proposes an ink containing a combination of a specific polyhydric alcohol and glycerin. Japanese Patent Application Laid-Open No. 2000-198267 (Patent Document 7) proposes an ink containing a solvent, a polymer binder, a mordant, a water-soluble curl preventing compound, a water-soluble desizing compound, a light-resistant compound, an antifoaming agent, and the like. ing.
[0006]
In addition to the above-mentioned publications, refer to JP-A-09-145538 (Patent Document 10), JP-A-11-12520 (Patent Document 11), and the like.
[0007]
[Patent Document 1]
JP-A-04-332775
[Patent Document 2]
JP-A-06-157555
[Patent Document 3]
JP 06-240189 A
[Patent Document 4]
JP-A-09-165538
[Patent Document 5]
JP-A-09-176538
[Patent Document 6]
JP-A-10-130550
[Patent Document 7]
JP-A-2000-198267
[Patent Document 8]
JP-A-09-145538
[Patent Document 9]
JP-A-11-12520
[0008]
[Problems to be solved by the invention]
However, according to the study of the present inventors, although the curl can be suppressed to some extent by the method described in the above-mentioned prior art, the improvement in image quality deterioration, kogation, image characteristics and recording stability of an obtained image is not achieved. There was room. Further, in particular, when a large amount of a curl suppressing substance is added in order to sufficiently suppress curling, the dischargeability often deteriorates.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a curl reduction method that sufficiently suppresses curl and makes it easier to handle printed matter of plain paper.
[0010]
[Means for Solving the Problems]
The ink jet recording method of the present invention,
In order to reduce curl after recording of the recorded matter, the recording material contains water, a colorant, and at least one compound selected from the following compounds 1) and 2), and has a surface tension of 35 mN / m or less. An inkjet recording method having a step of discharging ink toward a recording medium by an inkjet recording method,
The droplet volume per ink droplet is less than 3 pl;
Ink ejection amount per unit area is 3 × 10^-6ml / mm²3 × 10 or more^-5ml / mm²Below, and
A print head that ejects ink is relatively moved in a main scanning direction with respect to a predetermined area of the recording medium, and a plurality of main scans are performed to perform recording on the recording medium. Things.
[0011]
1) a polyhydric alcohol having a molecular weight Mw in the range of 100 ≦ Mw ≦ 1000,
2) Water-soluble amide compound.
[0012]
The ink used is urea, ethylene urea and HOH₂CH₂C-NH- (C = O) NH-CH₂CH₂The present invention is more effective when it contains at least one compound selected from OH.
[0013]
That is, the present invention includes the following embodiments.
(1) An ink containing water, a colorant, and at least one compound selected from the following compounds 1) and 2) and having a surface tension of 35 mN / m or less is recorded on a recording medium by an inkjet recording method. An inkjet recording method having a step of discharging toward
The droplet volume per ink droplet is less than 3 pl;
The ink ejection amount per unit area ranges from 3 × 10 −6 to 3 × 10 −5, and the print head that discharges ink is moved relative to a predetermined area of the recording medium in the main scanning direction. Performing a plurality of predetermined main scans while moving to record on the recording medium
An ink-jet recording method, characterized in that:
[0014]
1) a polyhydric alcohol having a molecular weight Mw in the range of 100 ≦ Mw ≦ 1000,
2) Water-soluble amide compound.
(2) The ink jet recording method according to the above (1), wherein the ink contains at least one kind of the compound 1) and at least one kind of the compound 2).
(3) The compound 2) is urea, ethylene urea and HOH₂CH₂C-NH- (C = O) NH-CH₂CH₂The ink jet recording method according to the above item (1), which is at least one compound selected from OH.
(4) The inkjet recording method according to the above item (2) or (3), wherein the total content of the compound selected from the compound 1) and the compound 2) in the ink is 10% by mass or more and 20% by mass or less.
(5) The ink jet recording method according to any one of the above items (1) to (6), wherein the hue of the ink is a hue selected from yellow, magenta, cyan, black, red, orange, green, blue and violet. .
(5) An ink containing water, a colorant, and at least one compound selected from the following compounds 1) and 2) and having a surface tension of 35 mN / m or less is recorded on a recording medium by an inkjet recording method. A curl reduction method for a recording medium having a step of discharging toward
Recording on the recording medium by performing a plurality of predetermined times of main scanning by relatively moving a print head that ejects ink in a main scanning direction with respect to a predetermined area of the recording medium;
The droplet volume per ink droplet is less than 3 pl,
Further, the ink ejection amount per unit area is 3 × 10^-6ml / mm²3 × 10 or more^-5ml / mm²Below
A curl reduction method, characterized in that:
[0015]
1) a polyhydric alcohol having a molecular weight Mw in the range of 100 ≦ Mw ≦ 1000,
2) Water-soluble amide compound.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to preferred embodiments.
[0017]
When forming an image by an ink jet recording method using an aqueous ink containing a colorant, the present inventors use a specific ink composition and determine the volume of an ink droplet per drop of ink and the image. It has been found that curl after recording can be sufficiently suppressed by controlling the number of recording passes and the amount of ink adhering to the recording medium during formation, and have reached the present invention.
[0018]
Therefore, first, factors causing curling of paper after ink jet recording will be described, and then factors capable of sufficiently suppressing curling after recording according to the present invention will be described.
[0019]
When moisture is applied to the paper, hydrogen bonds formed between the cellulose fibers of the paper are broken once. That is, the addition of moisture causes swelling of the cellulose and a chemical phenomenon. At this time, the penetration of the ink is not uniform in the depth direction of the paper, and the deeper the portion, the smaller the amount of ink. Since the portion used for the ink, that is, the fiber in contact with water swells, it warps to the opposite side of the surface to which water is applied, and curls, that is, causes minus curling. However, once absorbed water in the cellulose gradually evaporates, the cellulose starts to shrink, and the hydrogen bond once broken is recombined. At that time, the paper does not recombine at the cut position but recombines at another position, so that the paper gradually warps and curls in the direction of the surface to which moisture has been applied. That is, plus curl occurs. This plus curl causes a problem when ink jet recording is performed on plain paper or the like.
[0020]
The present inventor has sufficiently analyzed the phenomenon of water supply-swelling-minus curl and the phenomenon of evaporation-shrinkage-plus curl, particularly the structure of the compound added to the ink, the size of the ink droplets, and the amount of ink applied to the paper. As a result of intensive studies on how to suppress the positive curl according to the number of printing passes, the above-described specific compound is contained in the ink, and the size of the ink droplet, the amount of ink applied to the printing medium, and the printing pass are controlled. By doing so, the ink is fixed near the surface layer of the paper, and the curl suppressing component in the ink effectively penetrates between the celluloses of the fibers, and when the hydrogen bonds are recombined, the paper is liable to shrink. I found that it was trying to cause it.
[0021]
Hereinafter, preferred embodiments of the present invention will be described more specifically.
[0022]
(Droplet volume)
A preferred value of the droplet volume used in the curl reduction method of the present invention is less than 3 pl as a droplet volume per drop. In this way, by adjusting the volume of a droplet per drop and using the control of the number of recording passes described in the next section, the ink is closer to the surface layer of the recording medium, especially plain paper without the ink-ink receiving layer. Since the infiltration is completed, the thickness of the pulp fiber after recording contracts, and the curling force after recording is reduced.
[0023]
The recording medium used in the recording method using the ink according to the present invention is not particularly limited, and plain paper such as copy paper and bond paper is preferably used.
[0024]
Here, the plain paper includes copy paper, recycled paper for copy, plain paper for ink jet, plain paper for color ink jet, paper for both ink jet and electrophotography, Japanese paper and the like which are generally commercially available. More specifically, the paper surface is not coated with a special white pigment, or even if coated, the amount of coating is small and the pulp fibers of the underlying paper (base paper) are partially exposed. Including.
[0025]
(Number of recording passes)
In the recording method according to the present invention, a plurality of predetermined times (the number of recording buses) of main scanning are performed by moving a print head that ejects ink relative to a predetermined area of the recording medium in a main scanning direction. Record by.
[0026]
As described above, as the number of recording passes increases, for example, to 2, 3, 4, 6, 8, and 16 passes, as described above, the ink is more likely to remain on the surface layer of the recording medium, especially plain paper, and therefore the curl suppressing effect is large. Become. However, unnecessarily increasing the number of recording passes decreases the recording speed. In consideration of such a trade-off between the curl reduction amount and the printing throughput, the number of printing passes in the present invention is preferably 2 to 8 passes, more preferably 2 to 4 passes.
[0027]
For example, a preferred embodiment of a print pattern in two-pass printing is as follows. As shown in FIG. 2, in the first scan and the second scan, the image data is divided in such a manner as to be mutually complemented according to a certain arrangement. However, this image data arrangement (decimation pattern) is usually just It is most common to use a houndstooth check. The following is a description of such a recording method.
JP-A-60-214670, JP-A-60-214671, U.S. Pat. No. 4,622,561, U.S. Pat. No. 4,963,882 and U.S. Pat. No. 4,967,203.
Therefore, in the unit print area (here, in units of four pixels), printing is completed by the first scan for printing the staggered grid and the second scan for printing the inverted staggered grid.
[0028]
FIGS. 2A, 2B, and 2C show how a multi-head having eight nozzles is used to determine how recording in a certain area is completed when the staggered and inverted staggered patterns are used, respectively. It has been explained. First, in the first scan, a staggered pattern (hatched circles) is printed using the lower four nozzles (FIG. 2A). Next, in the second scan, the paper is fed by four pixels (1/2 of the head length), and the inverted zigzag pattern (white circles) is recorded (FIG. 2B). Further, in the third scan, the paper is fed again by four pixels (１ ／ of the head length) again, and the staggered pattern is printed again (FIG. 2C). In this manner, by alternately performing paper feed in units of four pixels and recording in a zigzag or inverted zigzag pattern, a recording area in units of four pixels is completed for each scan.
[0029]
Next, a four-pass printing method having four types of 4 × 4 basic patterns will be described. In this example, the same area is printed by four head scans using the basic masks (1) (1901), (2) (1902), (3) (1903), and (4) (1904) as shown in FIG. Is completed. Therefore, although the printing speed is lower than that of the two-pass method, the amount of ink applied per unit area in a certain period of time is small, so that the ink does not penetrate deeply in the paper surface direction and the ink easily stays on the paper surface, and the curl reduction effect is obtained. Excellent. Further, nozzle variation is reduced, and a smooth and high-quality image is obtained. Further, eight pass printing can be performed by setting eight types of basic patterns.
[0030]
(Amount of ink applied to recording medium)
The amount of ink applied to the recording medium is preferably 3 × 10^-5ml / mm²Is the amount of ink applied. By controlling the amount of applied ink as described above, the ink described in (1) and (2) is kept at a depth at which curl after recording can be sufficiently suppressed, and acts as a curl suppressing effect after recording. The ink application amount is 3 × 10^-5ml / mm²When the value exceeds, the ink penetration depth becomes too deep to obtain a sufficient curl suppressing effect.
[0031]
(Ink composition)
The ink composition preferably uses a polyhydric alcohol having a surface tension of 35 mN / m (dyn / cm) or less and a molecular weight Mw of 100 to 1,000. The reason why the surface tension needs to be controlled is to control the wettability of the ink with respect to a recording medium, particularly plain paper. If the surface tension is 35 mN / m or less, pulp fibers and various kinds of components constituting paper are required. More uniformly penetrates into additives and other components. If the surface tension exceeds 35 mN / m, it does not uniformly penetrate paper, which is not preferable. There is no problem if the surface tension of the ink is adjusted by a conventionally known method or a method of adding a surfactant. The action of the polyhydric alcohol having a molecular weight Mw of 100 or more and 1000 or less is curl suppression. When such a material is present in the ink, the above-described shrinkage of pulp fibers after recording is suppressed, and a curl suppressing effect is exerted.
[0032]
Specific examples of the polyhydric alcohol having a molecular weight Mw of 100 or more include 1,2-hexanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 1,2,2-propanediol. 6-hexanetriol, 3-methyl-1,3,5-pentanetriol, 1,2,4-butanetriol, and the like, and 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol , 3-methyl-1,5-pentanediol and the like, and polyethylene glycol 300, 400, 600 and the like are preferably used. Two or more of these can be used as needed.
[0033]
As the water-soluble amide compound, urea, ethylene urea and compounds represented by the following compounds A1 to A3 are preferably used.
[0034]
A water-soluble amide compound represented by the following structural formula A1:
[0035]
Embedded image

[0036]
[In the above formula, R is a straight-chain or branched-chain alkyl group having 2 to 4 carbon atoms substituted with a hydrogen atom or a hydroxyl group, (CH₂) NCOOH (n is 2 or 3), (CH₂) NSO₃Na (n is 2 or 3) or (CH₂) NSO₃H (n is 2 or 3), and m and n each independently represent an integer of 0-5. However, m and n do not become 0 at the same time. ];
A water-soluble amide compound represented by the following structural formula A2:
[0037]
Embedded image

[0038]
[In the above formula, each n and each m independently represent an integer of 0 to 5. However, m and n do not become 0 at the same time. ];as well as
A water-soluble amide compound having the following structural formula A3:
[0039]
Embedded image

[0040]
[In the above formula, R represents a phenylene group, a cyclohexylene group or a linear alkylene group having 2 to 4 carbon atoms, and m and n each independently represent an integer of 0 to 5. However, m and n do not become 0 at the same time. Further, when R is a phenylene group or a cyclohexylene group, the substitution position may be any of ortho, meta and para positions (1,2-, 1,3- and 1,4-position). ]
As the alkyl group substituted by the hydroxyl group for R in the structural formula A1, specifically, -CH₂CH₂OH, -CH₂CH₂CH₂OH, -CH₂CH₂CH₂CH₂OH,-(CH₂) CH (CH₃) OH, -CH₂CH₂CH (CH₃) OH, -CH₂CH (CH₃) CH₂OH, -CH (OH) CH₂CH₃, -CH (OH) CH₂CH₂CH₃, -CH₂C (CH₃)₂(OH), -CH (OH) CH₃, -CH (CH₃) CH₂OH, -C (CH₃)₂OH, -CH₂CH (OH) CH₂CH₃, -CH (CH₃) CH₂CH₂OH, -CH (CH₃) CH (OH) CH₃, -C (CH₃)₂CH₂OH, -CH (OH) CH (CH₃) CH₃  Or -C (OH) (CH₃) CH₂CH₃Can be mentioned.
[0041]
In the above, m and n of A1 to A3 are each more preferably 1 or 2. When R in A3 is a phenylene group or a cyclohexylene group, the substitution position is more preferably para-position (1,4-position). Furthermore, curling can be more effectively reduced with A2 and A3 type materials in which amide groups are symmetrically arranged in the molecule.
[0042]
A2 or A3 type material in which amide groups are symmetrically arranged in the molecule can reduce curling more effectively.
[0043]
The method for determining 1) the polyhydric alcohol having a molecular weight Mw in the range of 100 ≦ Mw ≦ 1000, and 2) the method for determining the molecular weight (Mw) of the water-soluble amide compound will be described below.
[0044]
Among the polyhydric alcohols of the above 1), those having a relatively small molecular weight and Mw of 100 to 150 were measured by the following method.
(1) JIS Handbook Chemical Analysis According to K0118 and K0123, the molecular weight of the present invention was directly obtained from mass spectrometry (GC-MS method and LC-MS method).
[0045]
Among the polyhydric alcohols of the above 1), those having a large molecular weight and Mw of 150 or more were measured by the following method.
(2) The average molecular weight was determined from the size exclusion chromatography (GPC method) according to K0124 and defined as the molecular weight of the present invention.
[0046]
For compounds having a molecular weight distribution, the weight average molecular weight in terms of polyethylene glycol was determined, and this was defined as the molecular weight of the present invention.
[0047]
The water-soluble amide compound of the above 2) was measured by the following method.
(3) The compound was subjected to structural identification by NMR, infrared analysis, elemental analysis, and the like, and the molecular weight was determined from this, and this was taken as the molecular weight of the present invention.
[0048]
Regarding the molecular weight of the polyhydric alcohol, the molecular weight Mw is preferably 100 or more and 1000 or less in order to achieve both the curl reduction effect and the reliability (fixation resistance, ejection stability, etc.) when used as an inkjet ink. Similarly, the preferred content of the polyhydric alcohol having a Mw of 100 or more and 1000 or less is determined in order to achieve both the curl reduction effect and the reliability (fixation resistance, ejection stability, etc.) when used as an inkjet ink. The content is 10 to 30% by mass, more preferably 10 to 20% by mass.
[0049]
A preferable addition amount of the compound is 10% by mass or more and 20% by mass or less in the ink in total of the polyhydric alcohol having a molecular weight Mw of 100 or more and 1000 or less and the water-soluble amide compound. When a polyhydric alcohol and a water-soluble amide compound are used in combination, the polyhydric alcohol having a molecular weight of 100 to 150 is more preferable.
[0050]
By controlling the four items described above, that is, the droplet volume per drop, the number of recording passes, the amount of ink adhering to the recording medium, and the ink composition as described above, curl after recording in ink jet recording is sufficiently reduced. It is possible to do.
[0051]
Next, the ink composition used will be described in more detail.
[0052]
(Colorant: dye, pigment)
The colorant of the recording ink is used by a water-soluble dye, a water-dispersible pigment, and a combination thereof. As the coloring agent, conventionally known orange, green, and blue dyes and pigments can be used without any problem in addition to black, cyan, yellow, and magenta.
[0053]
The ink used in the present invention may further include water (preferably, water is not general water containing various ions, but ion-exchanged water (deionized water)) and water-soluble organic. A solvent and other components such as a viscosity adjuster, a pH adjuster, a fungicide, a surfactant, an antioxidant, and the like are included as necessary.
[0054]
(dye)
In the present invention, dyes of colorants for recording colors are generally black, cyan, magenta, and yellow, and include anionic water-soluble dyes.
[0055]
The water-soluble dye having an anionic group used in the present invention is not particularly limited as long as it is a water-soluble acid dye, direct dye, or reactive dye described in Color Index (COLOUR INDEX). In addition, there is no particular limitation on dyes not described in the color index as long as they have an anionic group, for example, a sulfone group. These dyes are used in the ink in an amount of 1 to 10% by weight, preferably 1 to 5% by weight. Specific dyes include
C. I. Direct yellow 8, 11, 12, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 98, 100, 110;
C. I. Direct Red 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75, 79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226, 227, 228, 230;
C. I. Direct Blue 1, 15, 22, 25, 41, 76, 77, 80, 86, 90, 98, 106, 108, 120, 158, 163, 168, 199, 226;
C. I. Acid Yellow 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40, 42, 44, 76, 98, 99;
C. I. Acid Red 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51, 52, 80, 83, 87, 89, 92, 94, 106, 114, 115, 133, 134, 145, 158, 198, 249, 265, 289;
C. I. Acid Blue 1, 7, 9, 15, 22, 23, 25, 29, 40, 43, 59, 62, 74, 78, 80, 90, 100, 102, 104, 117, 127, 138, 158, 161;
C. I. Direct black 17, 19, 22, 31, 32, 51, 62, 71, 74, 112, 113, 154, 168;
C. I. Acid Black 2, 48, 51, 52, 110, 115, 156 C.I. I. Reactive black 1, 8, 12, 13; and
C. I. Food black 1,2
And the like. Of course, it is not limited more.
[0056]
In addition to the above, a dye having a carboxyl group as a solubilizing group may be used as a coloring material of an ink for recording color used in the present invention. Here, dyes exhibiting solubility dependence on pH are exemplified. These dyes are used in the ink in the range of 1 to 10% by mass, preferably 1 to 5% by mass.
[0057]
(Pigment)
Next, specific examples of the pigment used in the present invention include carbon black used in black ink. The carbon black is, for example, a carbon black manufactured by a furnace method or a channel method, and has a primary particle diameter of 15 to 40 mμ and a specific surface area of 50 to 300 m by a BET method.²/ G, DBP oil absorption of 40 to 150 m1 / 100 g, volatile matter of 0.5 to 10%, and pH of 2 to 9 are preferably used. As a commercially available product having such characteristics, for example, 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, No. 2200B (manufactured by Mitsubishi Kasei), RAVEN 255 (manufactured by Columbia), REGAL400R, REGAL 330R, REGAL 660R, MOGUL L (manufactured by Cabot), Color Black FW1, COLOR Black FW18, Color Black Slack, Col. Printex U (all manufactured by Degussa) and the like can be preferably used.
[0058]
Examples of the pigment used for the yellow ink include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 128 and the like.
[0059]
Examples of the pigment used in the magenta ink include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 112, C.I. I. Pigment Red 122 and the like.
[0060]
Examples of the pigment used for the cyan ink include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Vat Blue 4, C.I. I. Vat Blue 6 and the like.
[0061]
The pigment used is not limited to these. In addition to the above, of course, pigments newly produced for the present invention can also be used.
[0062]
When a pigment is used as a coloring material of the ink used in the present invention, the amount of the pigment is 1 to 20% by mass, preferably 2 to 12% by mass, based on the total weight of the ink. Use in the range.
[0063]
When a pigment is used, as the dispersant for incorporating the pigment into the ink, any dispersant can be used as long as it is a water-soluble resin, but the weight average molecular weight is 1,000 to 30,000. And those having a range of 3,000 to 15,000 are preferably used. Specific examples of such dispersants include styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, and maleic acid. , Maleic acid derivative, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative, vinyl acetate, vinylpyrrolidone, acrylamide, derivatives thereof and the like (at least one of which is at least one Block copolymer comprising a (hydrophilic monomer), a random copolymer, a graft copolymer or a salt thereof. Alternatively, natural resins such as rosin, shellac and starch can also be preferably used. These resins are soluble in an aqueous solution in which a base is dissolved, and are alkali-soluble resins. The water-soluble resin used as a pigment dispersant is preferably contained in the range of 0.1 to 5% by mass based on the total weight of the ink.
[0064]
In particular, in the case of an ink containing the above-described pigment, it is preferable that the entire ink is adjusted to be neutral or alkaline. Such a configuration is preferable because the solubility of the water-soluble resin used as a pigment dispersant can be improved, and an ink having more excellent long-term storage properties can be obtained. However, in this case, it may cause corrosion of various members used in the ink jet recording apparatus.
[0065]
Examples of the pH adjuster used in this case include, for example, various organic amines such as diethanolamine and triethanolamine, and inorganic alkali agents represented by alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide. And organic acids and mineral acids. The water-soluble resin as the pigment and the dispersant as described above is dispersed or dissolved in an aqueous liquid medium.
[0066]
As a method for preparing an ink containing a pigment as described above, first, a pigment is added to an aqueous medium containing at least a water-soluble resin and water as a dispersant, and after stirring, a dispersing unit described below is used. And a centrifugation treatment is performed as necessary to obtain a desired dispersion. Next, a sizing agent and appropriately selected additive components as described above are added to the dispersion and stirred to obtain an ink used in the present invention.
[0067]
In addition, when using the alkali-soluble resin as described above as a dispersant, it is necessary to add a base to dissolve the resin, as the bases in this case, monoethanolamine, Organic amines such as diethanolamine, triethanolamine, amine methylpropanol, and ammonia, and inorganic bases such as potassium hydroxide and sodium hydroxide are preferably used.
[0068]
In addition, in a method for preparing an ink containing a pigment, it is effective to perform premixing for 30 minutes or more before stirring and dispersing an aqueous medium containing the pigment. That is, such a premixing operation is preferable because the wettability of the pigment surface can be improved and the adsorption of the dispersant on the pigment surface can be promoted.
[0069]
The dispersing machine used in the above-mentioned pigment dispersion treatment may be any commonly used dispersing machine, and examples thereof include a ball mill, a roll mill, and a sand mill. Among them, a high-speed type sand mill is preferably used. Examples of such a type include a super mill, a sand grinder, a bead mill, an agitator mill, a Glen mill, a Dyno mill, a pearl mill, and a Kobol mill (all trade names).
[0070]
Further, when an ink containing a pigment is used in an ink jet recording method, a pigment having an optimum particle size distribution is used due to requirements for clogging resistance and the like, but a pigment having a desired particle size distribution is obtained. Methods include reducing the size of the grinding media in the disperser, increasing the filling rate of the grinding media, increasing the processing time, slowing the discharge speed, and classifying with a filter or centrifuge after grinding. And combinations of these methods.
[0071]
It is also possible to combine the above-mentioned water-soluble dyes and water-dispersible pigments for the purpose of subtle toning or for adjusting the color density. At this time, the aqueous dye and the water-dispersible pigment can be mixed in a range of 10: 1 to 1:10 according to the purpose.
[0072]
The preferable range of the physical properties of the recording ink in the present invention is around 25 ° C., the pH is 3 to 12, preferably 7 to 10, the surface tension is 10 to 60 mN / m, preferably 10 to 40 mN / m, and the viscosity is The pressure is 1 to 30 mPa · s (cps), preferably 1 to 5 mPa · s.
[0073]
(Water-soluble liquid medium)
In the present invention, it is preferable to use a water-soluble organic solvent which can be used by being mixed with water, as appropriate, in addition to the colorant and the compound serving as the curl reducing agent described above.
[0074]
As the water-soluble organic solvent used by mixing with water, for example,
(1) Alkyl alcohols having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol. ;
(2) amides such as dimethylformamide and dimethylacetamide;
(3) ketones or keto alcohols such as acetone and diacetone alcohol;
(4) ethers such as tetrahydrofuran and dioxane;
(5) alkylene glycols having 2 to 6 carbon atoms, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, ethylene glycol, propylene glycol, trimethylene glycol, and triethylene glycol;
(6) glycerin;
(7) lower alkyl ethers such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl, butyl) ether, and triethylene glycol monomethyl (or ethyl, butyl) ether;
(8) lower dialkyl ethers of polyhydric alcohols such as triethylene glycol dimethyl (or diethyl) ether and tetraethylene glycol dimethyl (or diethyl) ether;
(9) alkanolamines such as monoethanolamine, diethanolamine and triethanolamine; and
(10) Sulfolane, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like.
[0075]
The water-soluble organic solvents as described above can be used alone or as a mixture.
[0076]
Further, the content of water used can be in the range of 10 to 90% by mass, preferably 30 to 80% by mass of the total weight of the ink.
[0077]
(About recording device)
FIG. 1 is a schematic perspective view showing a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method and a liquid discharge device using the head according to the present invention, in which bubbles communicate with the atmosphere during discharge. is there. In FIG. 1, the inkjet printer includes a transport device 1030 intermittently transporting a sheet 1028 as a recording medium provided in a casing 1008 along a longitudinal direction in a direction indicated by an arrow P shown in FIG. The recording unit 1010 is configured to reciprocate substantially parallel to a direction S that is substantially perpendicular to the transport direction P of the paper 1028, and a moving drive unit 1006 as a driving unit that reciprocates the recording unit 1010.
[0078]
The transport device 1030 includes a pair of roller units 1022a and 1022b arranged to face each other substantially parallel to each other, a pair of roller units 1024a and 1024b, and a driving unit 1020 for driving each of these roller units. Thus, when the drive unit 1020 is activated, the sheet 1028 is nipped and conveyed by the respective roller units 1022a and 1022b and the roller units 1024a and 1024b in the direction of arrow P shown in FIG. It will be.
[0079]
The movement driving unit 1006 is arranged substantially parallel to the belt 1016 wound around the pulleys 1026a and 1026b arranged on the rotating shafts opposed to each other at a predetermined interval, and the carriage member 1010a of the recording unit 1010 arranged substantially parallel to the roller units 1022a and 1022b. And a motor 1018 for driving a belt 1016 connected to the motor 1010 in forward and reverse directions.
[0080]
When the motor 1018 is activated and the belt 1016 rotates in the direction of arrow R in FIG. 7, the carriage member 1010a of the recording unit 1010 is moved by a predetermined amount in the direction of arrow S in FIG. When the motor 1018 is activated and the belt 1016 rotates in the direction opposite to the direction indicated by the arrow R in FIG. 1, the carriage member 1010a of the recording unit 1010 moves in a predetermined direction in the direction opposite to the direction indicated by the arrow S in FIG. It will be moved by the moving amount. Further, at one end of the movement driving unit 1006, a recovery unit 1026 for performing an ejection recovery process of the recording unit 1010 is provided at a position serving as a home position of the carriage member 1010a so as to face the ink ejection port arrangement of the recording unit 1010. Is provided.
[0081]
The recording unit 1010 is configured such that inkjet cartridges 1012Y, 1012M, 1012C, and 1012B are detachably attached to a carriage member 1010a for each color, for example, yellow, magenta, cyan, and black, respectively. Be provided.
[0082]
【Example】
Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited by the following examples unless it exceeds the gist. In the following description, “parts” or “%” is based on mass unless otherwise specified.
[0083]
Examples 1 to 18
An ink having the following composition was prepared.
(Preparation of recording ink 1)
The following components were mixed, and the mixture was filtered under pressure through a membrane filter having a pore size of 0.2 μm to obtain Recording Ink 1.
C. I. Direct Blue 199: 3 copies
Polyethylene glycol (PEG) -300: 8 parts
Glycerin: 10 parts
Diethylene glycol: 8 parts
Acetyleneol EH (manufactured by Kawaken Fine Chemical): 1 part
Ion exchange water: 60 parts
(Preparation of recording ink 2)
The following components were mixed, and the mixture was filtered under pressure through a membrane filter having a pore size of 0.2 μm to obtain Recording Ink 1.
C. I. Direct Blue 199: 3 copies
PEG-300: 12 parts
Glycerin: 10 parts
Urea: 8 parts
Acetyleneol EH (manufactured by Kawaken Fine Chemical): 1 part
Ion exchange water: 69 parts
(Preparation of recording ink 3)
The following components were mixed, and the mixture was filtered under pressure through a membrane filter having a pore size of 0.2 μm to obtain Recording Ink 1.
C. I. Direct Blue 199: 3 copies
PEG-200: 12 parts
Glycerin: 10 parts
Ethylene urea: 8 parts
Acetyleneol EH (manufactured by Kawaken Fine Chemical): 1 part
Ion exchange water: 78 parts
(Preparation of recording ink 4)
The following components were mixed, and the mixture was filtered under pressure through a membrane filter having a pore size of 0.2 μm to obtain Recording Ink 1.
C. I. Direct Blue 199: 3 copies
PEG-200: 12 parts
Glycerin: 10 parts
HOH₂CH₂C-NH- (C = O) NH-CH₂CH₂OH: 8 parts
Acetyleneol EH (Kawaken Fine Chemical): 1 part
Ion exchange water: 78 parts
As the ink jet recording apparatus used here, the same recording apparatus as that shown in FIG. 1 was used. The recording head used had a recording density of 1200 dpi, and the driving conditions were a driving frequency of 10 kHz.
[0084]
Recording was performed with a combination of the recording inks 1 to 4 and the recording conditions shown in Table 1. As the recording paper, PB paper, both of which were manufactured by Canon Inc. and electrophotography, was used.
[0085]
[Table 1]

[0086]
The units in Table 1 are as follows.
Droplet volume: pl
Number of recording passes (times)
Ink application amount: × 10^-5ml / mm²
The curl amount of the recorded matter recorded under the above conditions was evaluated as follows.
(Curl evaluation)
The recorded matter was allowed to stand at normal temperature / humidity for 1 day, 4 days, and 7 days, respectively, and then the curl amount was measured. When the recording paper was curled in the concave direction, the distance from the tip of the curled paper to the ground surface of the paper was measured with a ruler. Numerical values were determined by calculating the average of four corners of the paper and calculating the curl amount. Table 1 shows the evaluation results.
Curl determination criteria are as follows.
A: Less than 20 mm: no problem
B: 20 mm or more and less than 35 mm: level at which there is no practical problem
C: 35 mm or more: Practical problem
Table 2 shows the curl evaluation results of Examples and Comparative Examples.
[0087]
[Table 2]

[0088]
As can be seen from Table 2, according to the present invention, a method for reducing post-recording curl by plain paper ink jet recording was shown.
[0089]
【The invention's effect】
As described above, according to the present invention, particularly with respect to the ink jet recording method on plain paper, the effect of sufficiently suppressing curling and greatly improving the handling of printed matter has been demonstrated.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a main part of an example of an ink jet printer on which a liquid discharge head can be mounted.
FIG. 2 is a diagram illustrating two-pass printing.
FIG. 3 is a diagram illustrating 4-pass printing.
[Explanation of symbols]
1008 Casing
1010 Recorder
1010a Carriage member
1012 cartridge
1012Y, M, C, B inkjet cartridge
1016 belt
1018 motor
1020 drive unit
1022a, 1022b Roller unit
1024a, 1024b Roller unit
1026 Recovery unit
1026a, 1026b Pulley
1028 paper
1030 Transport device

Claims (1)

An ink containing water, a colorant, and at least one compound selected from the following compounds 1) and 2) and having a surface tension of 35 mN / m or less is directed toward a recording medium by an inkjet recording method. An inkjet recording method having a discharging step,
The droplet volume per ink droplet is less than 3 pl;
The ink ejection amount per unit area ranges from 3 × 10 −6 to 3 × 10 −5, and the print head that discharges ink is moved relative to a predetermined area of the recording medium in the main scanning direction. An ink jet recording method, wherein the recording is performed on the recording medium by performing a plurality of main scans while moving the recording medium.
1) a polyhydric alcohol having a molecular weight Mw in the range of 100 ≦ Mw ≦ 1000,
2) Water-soluble amide compound.

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