JP4230212B2 - Pigment ink for inkjet recording and inkjet recording method - Google Patents

Description

【００９８】
参考例１〜４および比較例１〜４のインクについて、前述の評価試験方法に従って、（ａ）乾燥性、（ｂ）滲み性、（ｄ）光学濃度および（ｇ）吐出安定性を評価し、さらに（ｉ）総合評価を行った。結果を表２に示す。
【００９９】
【表２】

【０１００】
表２から、参考例１〜４が、乾燥性、滲み性、光学濃度および吐出安定性の特性すべてを高い水準で満足しているのに対し、水溶性樹脂を使用した比較例１〜４は、参考例１〜４に比べて、すべての性能が不充分であることが明らかである。
【０１０１】
参考例５および比較例５
下記の成分を下記の割合（％）で使用する以外は、参考例１と同様にして、参考例および比較例のインクを調製した。
【０１０２】
・自己分散型カーボンブラックＣｂ１ 表３に記載（％）
（平均粒子径３００ｎｍ、最小粒子径１０ｎｍ、最大粒子径６００ｎｍ）
・水分散性樹脂Ｐ１またはＳ１ 表３の記載（％）
・グリセリン １５．０％
・ジエチレングリコール １５．０％
・１，２−ヘキサンジオール １０．０％
・トリエチレングリコールモノブチルエーテル １０．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１０３】
表３において、「固形分」は、自己分散型カーボンブラックＣ１ｂと水分散性樹脂Ｐ１またはＳ１の樹脂分との合計量である固形分含量（％）を意味する。また、「重量比」は、自己分散カーボンブラックＣ１ｂの１００部に対する、水分散性樹脂の樹脂分の含有量（部）を意味する。
【０１０４】
得られた参考例５および比較例５のインクについて、前述の評価試験方法に従って、（ｂ）滲み性、（ｃ）混色性、（ｄ）光学濃度、（ｆ）定着性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表３に示す。
【０１０５】
【表３】

【０１０６】
なお、比較例５のＮｏ．１４および１５は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価は実施しなかった。
【０１０７】
参考例６および比較例６
下記の成分を下記の割合（％）で使用する以外は、参考例１と同様にして、参考例および比較例のインクを調製した。
【０１０８】
・自己分散型マゼンタ顔料Ｍ１ａ 表４に記載（％）
（平均粒子径２２０ｎｍ、最小粒子径１０ｎｍ、最大粒子径４２０ｎｍ）
・水分散性樹脂Ｐ１またはＳ１ 表４に記載（％）
・グリセリン １５．０％
・プロピレングリコール １５．０％
・１，２−ヘキサンジオール １０．０％
・テトラエチレングリコールモノブチルエーテル １０．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１０９】
表４において、「固形分」は、自己分散型マゼンタ顔料Ｍ１ａと水分散性樹脂Ｐ１またはＳ１の樹脂分との合計量である固形分含量（％）を意味する。また、「重量比」は、自己分散型マゼンタ顔料Ｍ１ａの１００部に対する、水分散性樹脂の樹脂分の含有量（部）を意味する。
【０１１０】
参考例６および比較例６のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｄ）光学濃度、（ｆ）定着性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表４に示す。
【０１１１】
【表４】

【０１１２】
なお、比較例６のＮｏ．１２および１３は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１１３】
表３および表４から、次のことが判る。
１）自己分散型顔料の含有量は０．５〜１２％の範囲から選択することが好ましい。自己分散型顔料濃度が、０．５％より低くなると光学濃度が著しく低下し許容範囲外となる。１２％より高いと、インク中で顔料の凝集・沈降が始まるので使用できない。
２）自己分散型顔料と水分散性樹脂の樹脂分との合計量である固形分含有量は、１．０〜２０％であることが必須である。固形分含有量が１．０％より低くなると、滲み、混色などが増大し、良好な記録画像を得ることができない。２０％より高いと、良好な吐出安定性が得られない。
３）自己分散型顔料と水分散性樹脂との含有比率は、自己分散型顔料１００部に対して水分散性樹脂２０〜５００部（樹脂分換算）であることが必須である。水分散性樹脂が２０部より少ないと、定着性が低くなり、混色も生じやすくなる。５００部よりも多いと、光学濃度が低下みられる。
【０１１４】
実施例１、参考例７および比較例７
表５に示す自己分散型カーボンブラックまたは自己分散型マゼンタ顔料を用い、表６に示す割合（％）で各成分を使用する以外は、参考例１と同様にして、本発明のインク、参考例のインクおよび比較例のインクを調製した。
【０１１５】
実施例１、参考例７および比較例７のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｄ）光学濃度、（ｅ）裏写り性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表６に併記する。
【０１１６】
表６中、自己分散型顔料の括弧内の数字は、それぞれの顔料の平均粒子径である。
【０１１７】
【表５】

【０１１８】
【表６】

【０１１９】
なお、比較例７のＮｏ．２は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１２０】
表６から、自己分散型顔料は、平均粒子径が２００〜５００ｎｍの範囲のものを使用しなければならないことが明らかである。平均粒子径が２００ｎｍよりも小さいと、滲み、混色および裏写りが生じる。平均粒子径が５００ｎｍよりも大きいと、顔料の凝集・沈降が起こり、インクの保存安定性と吐出安定性に問題が生じる。
【０１２１】
実施例２および比較例８
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、本発明のインクおよび比較例のインクを調製した。
【０１２２】
・自己分散型カーボンブラックＣ１ｃ ３．０％
（平均粒子径５００ｎｍ、最小粒子径１０ｎｍ、最大粒子径１μｍ）
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・アルカンジオール類▲１▼〜▲５▼ 表７に記載（％）
・グリセリン １５．０％
・ジエチレングリコール １０．０％
・トリエチレングリコールモノブチルエーテル １０．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１２３】
上記で得られた実施例２のインクおよび比較例８のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｅ）裏写り性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表７に示す。
【０１２４】
アルカンジオール類▲１▼〜▲５▼は、具体的には次のとおりである。
▲１▼ １，２−ヘキサンジオール
▲２▼ １，２−ペンタンジオール
▲３▼ １，２−ブタンジオール
▲４▼ １，６−ヘキサンジオール
▲５▼ １，５−ペンタンジオール
【０１２５】
【表７】

【０１２６】
なお、比較例８のＮｏ．４および５は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１２７】
参考例８および比較例９
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、参考例のインクおよび比較例のインクを調製した。
【０１２８】
・自己分散型マゼンタ顔料Ｍ１ａ ３．０％
（平均粒子径２９０ｎｍ、最小粒子径１０ｎｍ、最大粒子径５６０ｎｍ）
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・アルカンジオール類▲１▼〜▲５▼ 表８に記載（％）
・グリセリン １５．０％
・プロピレングリコール １０．０％
・テトラエチレングリコールモノブチルエーテル １０．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１２９】
上記で得られた参考例８のインクおよび比較例９のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｅ）裏写り性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表８に示す。
【０１３０】
なお、表８におけるアルカンジオール類▲１▼〜▲５▼は、表７と同様である。
【０１３１】
【表８】

【０１３２】
なお、比較例９のＮｏ．４および５は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１３３】
表７および８から、アルカンジオール類として、１，２−ヘキサンジオール、１，２−ペンタンジオールまたは１，２−ブタンジオールを用いる場合には、顔料・樹脂の分散性を高め、凝集・沈降を防ぐ働きがあり、平均粒子径の大きい顔料を使用したインクにおいても良好な保存安定性と吐出安定性が得られることが明らかである。また、アルカンジオール類の含有量は５〜３０重量％が好ましく、５重量％よりも低いとインクの保存安定性と吐出性に問題がみられ、３０重量％よりも高いと滲み・混色特性が低下し、裏抜けも生じる。
【０１３４】
実施例３および比較例１０
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、本発明のインクおよび比較例のインクを調製した。
【０１３５】
・自己分散型カーボンブラックＣ１ｃ ３．０％
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・１，２−ヘキサンジオール ５．０％
・グリセリン（表９では溶剤▲６▼） 表９に記載（％）
・ジエチレングリコール（表９では溶剤▲７▼） 表９に記載（％）
・トリエチレングリコールモノブチルエーテル ５．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部（表９に記載、％）
【０１３６】
上記で得られた実施例３のインクおよび比較例１０のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表９に示す。
【０１３７】
【表９】

【０１３８】
比較例１０のＮｏ．２および４〜６は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１３９】
参考例９および比較例１１
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、参考例のインクおよび比較例のインクを調製した。
【０１４０】
・自己分散型マゼンタ顔料Ｍ１ｂ ３．０％
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・１，２−ヘキサンジオール ５．０％
・グリセリン（表１０では溶剤▲６▼） 表１０に記載（％）
・プロピレングリコール（表１０では溶剤▲７▼） 表１０に記載（％）
・テトラエチレングリコールモノブチルエーテル ５．０％
・非イオン性界面活性剤（タージトール） １．０％
・水 残部（表１０の記載、％）
【０１４１】
上記で得られた参考例９のインクおよび比較例１１のインクについて、前述の評価試験方法にしたがって、（ｂ）滲み性、（ｃ）混色性、（ｇ）吐出安定性および（ｈ）保存安定性を評価し、さらに（ｉ）総合評価を行った。結果を表１０に示す。
【０１４２】
【表１０】

【０１４３】
比較例１１のＮｏ．２および４〜６は、吐出安定性および保存安定性を評価した段階で総合評価×が確定したので、他の評価項目を実施しなかった。
【０１４４】
表９および表１０から、有機溶剤の含有量は３０〜７０％であることが必須であり、グリセリン、ジエチレングリコール、プロピレングリコールまたはそれらの混合物より選択される有機溶剤を２０％以上含有することが好ましいことが判る。有機溶剤の含有量が３０％よりも少ないと、吐出不良が生じる。７０％よりも多いと、水の含有量が低くなりすぎ、水に分散する自己分散顔料及び水分散性樹脂の分散性が低下し凝集・沈降が生じ、インクの保存安定性、吐出性に問題が生じる。水の含有量はインク全量の２０％以上が好ましいことが判る。
【０１４５】
実施例４および比較例１２
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、本発明のインクおよび比較例のインクを調製した。
【０１４６】
・自己分散型カーボンブラックＣ１ｃ ３．０％
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・グリセリン １５．０％
・ジエチレングリコール １０．０％
・１，２−ヘキサンジオール １０．０％
・アルキレングリコールモノアルキルエーテル類 表１１に記載（％）
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１４７】
実施例４のインクおよび比較例１２のインクについて、前述の評価試験方法にしたがって、（ａ）乾燥性、（ｂ）滲み性、（ｃ）混色性および（ｅ）裏写りを評価し、さらに（ｉ）総合評価を行った。結果を表１１に示す。
【０１４８】
【表１１】

【０１４９】
参考例１０および比較例１３
下記の成分を下記に示す割合（％）で使用する以外は、参考例１と同様にして、参考例のインクおよび比較例のインクを調製した。
【０１５０】
・自己分散型マゼンタ顔料Ｍ１ｂ ３．０％
・水分散性ポリエステル樹脂Ｐ１ ４．０％
・グリセリン １５．０％
・プロピレングリコール １０．０％
・１，２−ヘキサンジオール １０．０％
・アルキレングリコールモノアルキルエーテル類 表１２に記載（％）
・非イオン性界面活性剤（タージトール） １．０％
・水 残部
【０１５１】
参考例１０のインクおよび比較例１３のインクについて、前述の評価試験方法にしたがって、（ａ）乾燥性、（ｂ）滲み性、（ｃ）混色性および（ｅ）裏写りを評価し、さらに（ｉ）総合評価を行った。結果を表１２に示す。
【０１５２】
【表１２】

【０１５３】
表１１および１２から、アルキレングリコールアルキルエーテルをインク全量の５〜２０％含有させるのが好ましいことが判る。アルキレングリコールアルキルエーテルが５％よりも低いとインクの乾燥性が不良となり混色等の問題が生じる。２０％よりも高いとインクの浸透性が高くなりすぎ、裏写り、滲みなどが生じる。また、アルキレングリコールアルキルエーテルとしては、ジプロピレングリコール−ｎ−プロピレンエーテル、ジエチレングリコール−ｎ−ブチルエーテル、トリエチレングリコール−ｎ−ブチルエーテル、テトラエチレングリコール−ｎ−ブチルエーテル、プロピレングリコール−ｎ−ブチルエーテル、ジプロピレングリコール−ｎ−ブチルエーテルなどが好ましいことが判る。
【０１５４】
【発明の効果】
本発明によれば、色滲み、混色、裏写りなどがなく、高い光学濃度を有し、定着性の良好な記録画像を形成できるとともに、保存安定性、吐出安定性にも優れ、さらにインク液滴の微細化にも対応できるインクジェット記録用顔料インクが提供される。
【０１５５】
本発明によれば、１，２−アルカンジオールの含有量を５〜３０重量％という特定の範囲から選択することによって、本発明インクの保存安定性がさらに向上する。
【０１５６】
本発明によれば、１，２−アルカンジオールとして上記の特定のものを使用することによって、本発明インクの保存安定性が一層向上する。
【０１５７】
本発明によれば、１，２−アルカンジオール以外の有機溶剤として上記の特定のものを、２０重量％という特定量以上使用することによって、本発明インクの吐出安定性がさらに向上する。
【０１５８】
本発明によれば、１，２−アルカンジオール以外の有機溶剤として上記の特定のものを、５〜２０重量％という特定量使用することによって、本発明インクの記録媒体に対する浸透性を、さらに適度な範囲にすることができる。
【０１５９】
本発明によれば、水を２０重量％という特定量以上使用することによって、本発明インクの保存安定性がさらに向上する。
【０１６０】
本発明によれば、水分散性樹脂として特定のものを使用することによって、本発明インクのよる記録画像における色滲みの発生をさらに抑制し、さらに高い光学濃度を有する記録画像を形成することができる。
【０１６１】
本発明によれば、自己分散型顔料の含有量を０．５〜１２重量％という特定の範囲から選択することによって、本発明インクの保存安定性がさらに向上し、光学濃度がさらに高い記録画像を形成することができる。
【０１６２】
本発明によれば、本発明インクを用い、インクジェットプリンタで記録を行うことによって、記録を円滑に行うことができるとともに、高品位の記録画像を形成することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pigment ink for inkjet recording and an inkjet recording method.
[0002]
[Prior art]
Conventionally, as ink for inkjet recording, a dye ink in which a dye as a color material is dissolved or dispersed in water is used. However, recorded images with dye inks are insufficient in water resistance and light resistance.
[0003]
Accordingly, development of a pigment ink using a pigment as a color material instead of a dye is underway. When pigment ink is used, a recorded image having excellent water resistance and light resistance can be obtained. In a pigment ink containing water as a main solvent, since the pigment is insoluble in water, the pigment is dispersed by blending a dispersant such as a surfactant and a polymer compound. In order to disperse the pigment with the surfactant, a large amount of the surfactant is required. However, if a large amount of surfactant is used, the surface tension of the ink is too low, so that the ink penetrates to the inside or the back surface of the recording medium, color bleeding, color mixing between adjacent different colors, and show-through. As a result, a decrease in optical density or the like occurs, and the quality of the recorded image decreases. This is particularly noticeable when the recording medium is plain paper. In addition, the surfactant generates bubbles in the ink, which lowers the ejection stability of the ink, and the ink is not ejected accurately, resulting in printing unevenness. On the other hand, when a polymer compound is used, there is a problem that the viscosity of the ink is increased and the discharge nozzle is easily clogged, the ink droplets are reduced, and the optical density of the recorded image is lowered. Further, when a highly hydrophilic resin is used as the polymer compound, the pigment is pulled into the recording medium, the original color density of the pigment is not achieved, and the optical density of the recorded image is lowered.
[0004]
In view of the drawbacks of pigment inks containing water as the main solvent, studies have been made focusing on resin emulsions among polymer compounds, and various pigment inks have been proposed. For example, a pigment ink containing a resin emulsion such as a (meth) acrylic resin emulsion in a resin solid content of 2 to 18% by weight (see Patent Document 1), a resin emulsion containing a resin particle having an average particle diameter of 50 nm or less in resin solid content Pigment ink containing 0.5 to 10% by weight (see Patent Document 2), containing 10 to 100 parts by weight of resin emulsion (solid resin content) with respect to 100 parts by weight of pigment having an average particle size of 0.3 to 1.2 μm A pigment ink (see Patent Document 3), a pigment, a resin emulsion, and a pigment ink containing a polyol having 5 or more saccharides or hydroxyl groups (see Patent Document 4) have been proposed. There has also been proposed a method of recording an image by separately ejecting a pigment and a resin emulsion onto an image forming portion of a recording medium (see Patent Document 5). However, in the pigment ink containing the resin emulsion, the dispersion state of the pigment is likely to become unstable due to the interaction between the organic emulsion, other additives, etc. to be blended for adjusting the ink characteristics and the resin emulsion. Combinations of organic solvents, additives and resin emulsions are limited. Even when an optimal combination is selected, the obtained pigment ink has a low fixability to a recording medium, so a recorded image with the pigment ink is easily damaged by rubbing with other recording media. Furthermore, the action of the resin emulsion as the dispersant tends to cause blurring of the recorded image and a decrease in optical density.
[0005]
On the other hand, hydrophilicity (dispersibility in water) is imparted to the pigment by surface modification. For example, a polymer compound is grafted onto carbon black (see, for example, Patent Document 6, Patent Document 7, Patent Document 8, and Patent Document 9), or a hydrophilic group such as a carboxyl group or a sulfone group using a phenyl group or an alkyl group as a linking group. Introducing a functional functional group on the surface of carbon black (see Patent Document 10). Recently, not only carbon black but also self-dispersing color pigments having hydrophilic functional groups introduced on the surface of organic pigments are commercially available. Further, various studies have been made on pigment inks containing self-dispersing pigments. For example, pigment inks containing self-dispersing pigments and acrylic resins (see Patent Document 11), self-dispersing pigments, and polyoxyethylene sorbitan fatty acids. A pigment ink containing an ester (see Patent Document 12), a self-dispersing pigment, a glycol ether, a water-soluble resin, and a pigment ink containing water (see Patent Document 13) have been proposed.
[0006]
Since the self-dispersing pigment does not require a dispersant, the disadvantages of the pigment ink containing the dispersant are improved to some extent. However, particularly when the recording medium is plain paper, it is unavoidable that color bleeding, color mixing, show-through, a decrease in optical density, and the like occur due to the permeability and dryness of the ink to the recording medium. Conventional techniques represented by Patent Documents 11 to 13 and the like are effective in preventing color blurring. However, on the other hand, the storage stability of the ink is lowered, and pigment aggregation and sedimentation occur, which tends to adversely affect the ejection stability.
[0007]
In addition, in the ink jet recording system, in order to obtain a higher-definition recorded image, the ink droplets ejected to the recording medium are being miniaturized. In order to cope with this, self-dispersing pigments having an average particle diameter of about 100 nm are used from the viewpoints of dispersibility, storage stability, and the like. However, when such a self-dispersing pigment is used, color bleeding or color mixing occurs in the recorded image, resulting in a decrease in optical density.
[0008]
As described above, even a pigment ink containing a self-dispersing pigment can form a high-quality recorded image without color bleeding, color mixing, show-through, optical density reduction, etc., and has high storage stability and ejection stability. Nothing that meets the standards is available.
[0009]
[Patent Document 1]
JP-A-56-28256
[Patent Document 2]
JP-A-4-18462
[Patent Document 3]
JP-A-4-332774
[Patent Document 4]
JP-A-6-212106
[Patent Document 5]
JP 2000-34432 A
[Patent Document 6]
Japanese Patent Publication No. 1-49369
[Patent Document 7]
JP-A-1-79278
[Patent Document 8]
JP-A-6-128517
[Patent Document 9]
Japanese Patent Laid-Open No. 5-230410
[Patent Document 10]
US Pat. No. 5,571,311
[Patent Document 11]
Japanese Patent Laid-Open No. 11-181340
[Patent Document 12]
JP 2000-169769 A
[Patent Document 13]
JP 2000-169772 A
[Patent Document 14]
International Publication No. 98/21284 Pamphlet
[0010]
[Problems to be solved by the invention]
An object of the present invention is that there is no color bleeding, color mixing, show-through, etc., and a high-quality recorded image having high optical density and excellent fixability can be formed, and storage stability and ejection stability are at a high level. Ink jet recording pigment ink and ink jet recording method that can satisfy the above-mentioned requirements and can sufficiently cope with the miniaturization of ink droplets.
[0011]
[Means for Solving the Problems]
  The present invention contains at least a self-dispersing pigment, a water-dispersible resin, water and an organic solvent, and the average particle size of the self-dispersing pigment isOver 300nm and below 500nmThe solid content of the self-dispersing pigment and the water-dispersible resin in the ink is 1.0 to 20% by weight of the total amount of the ink, and the water-dispersible resin is used with respect to 100 parts by weight of the self-dispersing pigment. Ink containing 20 to 500 parts by weight of the ink, wherein the organic solvent content is 30 to 70% by weight of the total amount of the ink, and the organic solvent contains at least 1,2-alkanediol. Ink.
[0012]
According to the present invention, in an ink containing a self-dispersing pigment, a water-dispersible resin, water and an organic solvent, the solid particle is the average particle diameter of the self-dispersing pigment and the total amount of the self-dispersing pigment and the water-dispersing resin. By making the content, the blending ratio of the water-dispersible resin with respect to the self-dispersing pigment, and the content of the organic solvent into a specific range, and further making the specific organic solvent essential, the water-dispersible resin can cause bleeding of recorded images and The present inventors have succeeded in obtaining a pigment ink for inkjet recording that does not cause a decrease in optical density and fulfills the object of the present invention.
[0013]
The pigment ink for ink-jet recording of the present invention (hereinafter referred to as “the ink of the present invention”) has appropriate penetrability and drying properties with respect to the recording medium and is difficult to penetrate into the recording medium, or the inside or the inside of the recording medium. Because it does not penetrate to the back side and dries quickly, color bleeding, color mixing, show-through, etc. do not occur, it has a high optical density, can form a recorded image with excellent fixability, and is stable in storage. Also, it has excellent discharge stability and does not cause clogging of the discharge nozzle, which hinders printing. For example, high-quality recorded images can be formed even when high-speed printing or large-volume continuous printing is performed. Can do. Furthermore, the ink of the present invention can form a high-quality recorded image without affecting printing even if the ink droplets are miniaturized.
[0014]
The ink of the present invention contains 1,2-alkanediol in an amount of 5 to 30% by weight based on the total amount of the ink.
[0015]
According to the present invention, the storage stability of the ink of the present invention is further improved by selecting the content of 1,2-alkanediol from a specific range of 5 to 30% by weight.
[0016]
In the ink of the present invention, the 1,2-alkanediol is one or a mixture of two or more selected from 1,2-butanediol, 1,2-pentanediol and 1,2-hexanediol. To do.
[0017]
According to the present invention, the storage stability of the ink of the present invention is further improved by using the above-mentioned specific 1,2-alkanediol.
[0018]
The ink of the present invention is characterized in that it contains 20% by weight or more of an organic solvent, which is one or a mixture of two or more selected from glycerin, diethylene glycol, and propylene glycol.
[0019]
  According to the present invention, the discharge stability of the ink of the present invention is further improved by using the above-mentioned specific solvent other than 1,2-alkanediol in an amount of 20 wt% or more.
  The ink of the present invention is characterized by containing an organic solvent, which is a mixture selected from glycerin and diethylene glycol, by 40% by weight of the total amount of the ink.
[0020]
The ink of the present invention is characterized by containing 5 to 20% by weight of an organic solvent, which is one or a mixture of two or more selected from alkylene glycol alkyl ethers.
[0021]
According to the present invention, the organic solvent other than 1,2-alkanediol is used in a specific amount of 5 to 20% by weight of the above-mentioned specific solvent, thereby further increasing the permeability of the ink of the present invention to the recording medium. Range.
[0022]
The ink of the present invention is characterized by containing 20% by weight or more of the total amount of water.
[0023]
According to the present invention, the storage stability of the ink of the present invention is further improved by using water in an amount of 20% by weight or more.
[0024]
The ink of the present invention is characterized in that the water-dispersible resin is one or a mixture of two or more selected from polyester resins and styrene-acrylic resins.
[0025]
According to the present invention, by using a specific water-dispersible resin, it is possible to further suppress the occurrence of color bleeding in the recorded image by the ink of the present invention and to form a recorded image having a higher optical density. it can.
[0026]
The ink of the present invention contains a self-dispersing pigment in an amount of 0.5 to 12% by weight based on the total amount of the ink.
[0027]
According to the present invention, by selecting the content of the self-dispersing pigment from a specific range of 0.5 to 12% by weight, the storage stability of the ink of the present invention is further improved, and the recorded image has a higher optical density. Can be formed.
[0028]
The present invention is an ink jet recording method characterized in that the image of the present invention is ejected to form an image on a recording medium.
[0029]
According to the present invention, by using the ink of the present invention and recording with an ink jet printer, recording can be performed smoothly and a high-quality recorded image can be formed.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
The ink of the present invention is a composition comprising a self-dispersing pigment, a water-dispersible resin and an organic solvent as essential components, with the balance being water.
[0031]
The ink of the present invention satisfies all of the following features (1) to (5), whereby the desired excellent effects can be achieved.
[0032]
  (1) Average particle size of self-dispersing pigment
  The average particle size of the self-dispersing pigment isOver 300nm and below 500nmIt is.300nm or lessThen, bleeding, color mixing, and show-through tend to occur in the recorded image. On the other hand, if it exceeds 500 nm, the discharge nozzle is likely to be clogged. In addition, due to the precipitation of the self-dispersing pigment, the ejection stability and storage stability of the ink are lowered.
[0033]
(2) Solid content
The solid content, which is the total amount of the self-dispersing pigment and the water-dispersible resin, is 1.0 to 20% by weight of the total amount of the ink. If it is less than 1.0% by weight, bleeding, color mixing and the like increase, and a high-quality recorded image cannot be formed. If it exceeds 20% by weight, good ejection stability cannot be obtained.
[0034]
(3) Content ratio of self-dispersing pigment and water-dispersible resin
The water-dispersible resin is contained in an amount of 20 to 500 parts by weight in terms of resin with respect to 100 parts by weight of the self-dispersing pigment. If it is less than 20 parts by weight, the fixability is poor and color mixing tends to occur. On the other hand, if it exceeds 500 parts by weight, the optical density of the recorded image is lowered.
[0035]
(4) Content of organic solvent
The content of the organic solvent is 30 to 70% by weight of the total amount of ink. If it is less than 30% by weight, the ejection stability is lowered. On the other hand, when it exceeds 70% by weight, the pigment and the water-dispersible resin are aggregated and settled, and the storage stability and the ejection stability are lowered.
[0036]
(5) Inclusion of 1,2-alkanediol
It is essential to contain 1,2-alkanediol as the organic solvent. When 1,2-alkanediol is not included, storage stability and ejection stability are lowered.
[0037]
Hereinafter, each component of the ink of the present invention will be described.
(Self-dispersing pigment)
Self-dispersing pigments are those in which a hydrophilic functional group is introduced on the surface of the pigment to impart water dispersibility. Self-dispersing pigments do not require a dispersant.
[0038]
  Self-dispersing pigments have an average particle size as described above.Over 300nm and below 500nmIt is. The particle size distribution range of the self-dispersing pigment is more preferably in the range of 50 nm to 1 μm. The average particle size, minimum particle size, and maximum particle size of the self-dispersing pigment can be adjusted by appropriately changing the treatment conditions in the pigment pulverization step, salting-out / filtration and ultrafiltration purification steps.
[0039]
Known pigments can be used as the raw material of the self-dispersing pigment, and examples thereof include inorganic pigments such as black pigments, organic pigments such as cyan pigments, magenta pigments, and yellow pigments. Examples of the black pigment include carbon black such as acidic carbon, neutral carbon, and basic carbon. Carbon black is produced by various methods such as a channel black method, a furnace black method, a lamp black method, and an acetylene black method. When a specific example of the organic pigment is indicated by a color index number (CI), examples of the cyan pigment include C.I. I. Pigment Blue-1, 2, 3, 15, 15: 1, 15: 3, 15:34, 16, 22, 60, and the like. Examples of magenta color pigments include C.I. I. Pigment Red 5, 7, 12, 48, 48: 1, 57, 112, 122, 123, 146, 168, 184, 202, and the like. Examples of yellow pigments include C.I. I. Pigment Yellow-1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154 and the like.
[0040]
Examples of the hydrophilic functional group introduced on the surface of the pigment include a carbonyl group, a carboxyl group, a hydroxyl group, a sulfone group, and an ammonium group. One or more hydrophilic functional groups are introduced on the surface of the pigment. The hydrophilic functional group introduced into the surface of the pigment may be combined with an appropriate cation or anion to form a salt.
[0041]
In order to introduce a hydrophilic functional group to the pigment surface, a known method can be used. For example, a method of reacting an oxidation treatment, a sulfonation treatment, an aromatic azo compound, an alkylazo compound, etc. with a pigment and introducing a hydrophilic functional group onto the pigment surface using a phenyl group, an alkyl group, etc. as a linking group, a cup of a silane compound, etc. Examples thereof include a treatment with a ring agent, a polymer grafting treatment, and a plasma treatment. Two or more of these methods may be combined.
[0042]
Commercially available self-dispersing pigments can also be used. Specific examples thereof include, for example, Cab-o-jet 200 and Cab-o-jet 300 (both trade names) manufactured by Cabot Corporation, BONJET BLACK CW-1 and Microjet Black CW-1 manufactured by Orient Chemical Industries, Ltd. (Both are trade names).
[0043]
From among the self-dispersing pigments listed above, those having an average particle size that meets the definition of the present invention may be selected.
[0044]
A self-dispersion type pigment can be used individually by 1 type, or can use 2 or more types together.
The content of the self-dispersing pigment is not particularly limited. However, in consideration of obtaining a recorded image having a sufficient optical density and preventing aggregation and sedimentation thereof, it is usually 0.5 to 12% by weight of the total amount of ink. If it is less than 0.5% by weight, a recorded image having a sufficient optical density cannot be obtained. On the other hand, when the content exceeds 12% by weight, aggregation and sedimentation occur, and the storage stability and ejection stability of the ink decrease.
[0045]
(Water-dispersible resin)
The water dispersible resin is used as a binder, for example. By selecting the blending amount of the water-dispersible resin with respect to the self-dispersible pigment from the specific range while maintaining the solid content, which is the total amount of the self-dispersible pigment and the water-dispersible resin, within the specific range. Thus, it is possible to obtain an ink that is excellent in permeability (drying property) to a recording medium and that can form a recorded image having a high optical density without color bleeding even when the recording medium is plain paper.
[0046]
When a water-soluble resin is used in place of the water-dispersible resin, nozzle clogging, color bleeding, and decrease in optical density due to high viscosity of the ink cannot be avoided even if the specific content ratio is used.
[0047]
As the water dispersible resin, known resins can be used, and examples thereof include polyester resin, styrene resin, styrene-acrylic resin, maleic acid resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, polyurethane resin and the like. Among these, polyester resins, styrene-acrylic resins, and the like are preferable.
[0048]
The water dispersible resin may be used after being emulsified according to a known method.
A commercially available water-dispersible resin emulsion may also be used. Commercially available products include, for example, Bayonal (trade name, water-dispersible polyester resin emulsion) manufactured by Toyobo Co., Ltd., John Crill (trade name, water-dispersible styrene-acrylic resin emulsion) manufactured by Johnson Polymer Co., Ltd., Japan Paint Co., Ltd. microgel (trade name, water dispersible styrene-acrylic resin emulsion), Dai Nippon Ink Chemical Co., Ltd. bon coat (trade name, water dispersible styrene-acrylic resin emulsion), etc. Can be mentioned.
[0049]
A water-dispersible resin can be used individually by 1 type, or can use 2 or more types together.
The water-dispersible resin is used in the range of 1.0 to 20% by weight of the total amount of the ink of the present invention as the solid content, which is the total amount with the self-dispersing pigment.
[0050]
The water-dispersible resin is used in a range of 20 to 500 parts by weight with respect to 100 parts by weight of the self-dispersing pigment while maintaining a specific range of the solid content.
[0051]
〔Organic solvent〕
In the present invention, as described above, the organic solvent is contained in an amount of 30 to 70% by weight based on the total amount of the ink of the present invention.
[0052]
Furthermore, in the present invention, it is essential to contain 1,2-alkanediol as the organic solvent. 1,2-alkanediol is used, for example, to adjust the storage stability of the ink of the present invention. The 1,2-alkanediol is not particularly limited. However, in consideration of further improving the storage stability of the ink of the present invention, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol, etc. 2-alkanediol is preferred. The content of 1,2-alkanediol is not particularly limited. However, in consideration of further improving the storage stability of the ink of the present invention, it is usually 5 to 30% by weight of the total amount of the ink.
[0053]
The ink of the present invention contains other organic solvent together with 1,2-alkanediol. Other organic solvents are used, for example, to adjust the storage stability, ejection stability, permeability to the recording medium, and the like of the ink of the present invention. As another organic solvent, a water-soluble organic solvent is preferable. Known water-soluble organic solvents can be used, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1, Multivalent alcohols such as 2-hexanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, and petriol -Monohydric alcohols such as alcohols, ethanol, isopropyl alcohol, butyl alcohol, benzyl alcohol, glycol ethers such as triethylene glycol-n-butyl ether, tetraethylene glycol-n-butyl ether Alkylene glycol such as dipropylene glycol-n-propylene ether, diethylene glycol-n-butyl ether, triethylene glycol-n-butyl ether, tetraethylene glycol-n-butyl ether, propylene glycol-n-butyl ether, dipropylene glycol-n-butyl ether Alkyl ethers, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, formamide, N-methyl Amides such as formamide, formamide, N, N-dimethylformamide, monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, Examples include amines such as triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol, thiodiglycerol, ethylene urea, and urea, propylene carbonate, ethylene carbonate, and γ-butyrolactone.
[0054]
  Among these, from the viewpoint of further improving the ejection stability of the ink of the present invention, one or more water-soluble organic solvents selected from glycerin, diethylene glycol and propylene glycol are used in an amount of 20% by weight of the total amount of the ink of the present invention. It is preferable to use the above.
  Moreover, it is preferable to contain 40% by weight of the total amount of the ink of the present invention of an organic solvent which is a mixture selected from glycerin and diethylene glycol.
[0055]
Further, from the viewpoint of further improving the permeability and drying property of the ink of the present invention with respect to the recording medium, one or two or more water-soluble organic solvents selected from alkylene glycol alkyl ethers are used in the total amount of the ink of the present invention. It is preferred to use ~ 20% by weight. Alkylene glycol alkyl ethers have a low vapor pressure and act as ink wetting agents and also as ink penetrants on recording media. The combined use of the alkylene glycol alkyl ethers and the water-dispersible resin is a particularly preferable combination in order to increase the permeability of the ink of the present invention into the recording medium.
[0056]
Organic solvents other than 1,2-alkanediol can be used alone or in combination of two or more.
[0057]
In the ink of the present invention, a preferable combination of organic solvents is (i) one or two or more selected from 1,2-alkanediols in an amount of 5 to 30% by weight of the total amount of the ink and (b) alkylene glycol alkyl ether. One or more water-soluble organic solvents selected from the group consisting of 5 to 20% by weight of the total amount of the ink and the balance being selected from (iii) glycerin, diethylene glycol and propylene glycol The total amount is 30 to 70% by weight of the total amount of ink. Furthermore, a combination in which the content of the other organic solvent is appropriately adjusted within the specified range so that the content of the water-soluble organic solvent (c) is 20% by weight or more of the total amount of the ink is particularly preferable.
[0058]
〔water〕
The content of water is usually the remainder after using a predetermined amount of the self-dispersing pigment, the water-dispersible resin, and the organic solvent. However, considering the storage stability of the ink of the present invention, the water content is preferably 20% by weight or more of the total amount of the ink.
[0059]
[Surfactant]
The ink of the present invention may contain a surfactant as long as the preferable characteristics are not impaired. For example, the surfactant adjusts the surface tension of the ink of the present invention, assists the dispersion of the self-dispersing pigment so that the ink of the present invention is smoothly ejected from the ejection nozzle, or is applied to a recording medium using an organic solvent. To help the penetration effect. Therefore, since the surfactant is not used as a pigment dispersant, the amount of the surfactant added may be greatly reduced.
[0060]
As the surfactant, anionic surfactants, nonionic surfactants and the like are preferable, and nonionic surfactants are particularly preferable. Nonionic surfactants include, for example, polyoxyethylene surfactants, polyoxypropylene surfactants, polyoxy (ethylene-propylene) nonionic surfactants, acetylene glycol, oxyethylene adducts of acetylene glycol, polyoxy Ethers such as ethylene nonylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene olein Acid ester, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, polyoxy Esters such as ethylene stearates, Other fluorine alkyl esters, such as fluorine-containing surfactants such as perfluoroalkyl carboxylate are exemplified. Surfactant can be used individually by 1 type, or can use 2 or more types together. The content of the surfactant is not particularly limited. However, it is usually 0.01 to 3% by weight of the total amount of the ink of the present invention.
[0061]
[Other ink components]
The ink of the present invention can be blended with one or more additives conventionally used in ink jet recording pigment inks as long as the preferred characteristics are not impaired. Examples of the additive include antiseptic / antifungal agents, pH adjusters, chelating reagents, and rust inhibitors. Examples of antiseptic / antifungal agents include proxel (trade name), sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, and sodium pentachlorophenol. As the pH adjuster, any substance can be used as long as the pH can be adjusted to 7 or more without adversely affecting the ink to be prepared. For example, amines such as diethanolamine and triethanolamine, water Alkali metal hydroxides such as lithium oxide, sodium hydroxide, potassium hydroxide, etc., alkali metals such as ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, etc. And carbonates. Examples of chelate trials include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like. Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, and dicyclohexyl ammonium nitrite.
[0062]
Furthermore, the ink of the present invention is a water-soluble ultraviolet absorber, a water-soluble infrared absorber, a dissolution aid, an antioxidant, an antifoaming agent, a viscosity modifier, a clogging inhibitor, a bactericidal agent, as long as the preferable characteristics are not impaired. An agent or the like may be included.
[0063]
The ink of the present invention uses, for example, a predetermined amount of a self-dispersing pigment, a water-dispersible resin and an organic solvent, and if necessary, an appropriate amount of other additives, and water is added thereto to make the total amount 100% by weight. It can be prepared by adjusting and dispersing or mixing each component in water.
[0064]
Dispersion is performed using a normal disperser. Examples of the disperser include a disperser, a sand mill, a homogenizer, a ball mill, a bead mill, a paint shaker, and an ultrasonic disperser.
[0065]
The mixing is performed by a stirrer equipped with a stirring blade, a high-speed disperser, an emulsifier or the like.
[0066]
The ink of the present invention obtained in this way can be used as it is, but may be filtered prior to its use. Filtration is performed, for example, using a filter having a pore size of about 0.3 to 1.2 μm, under normal pressure, under pressure, or under reduced pressure.
[0067]
The ink of the present invention can be used not only as a water-based pigment ink for an ink jet recording system but also for virtually all uses in which a water-based ink is used. Specific examples of applications include printing inks such as gravure inks, water-based paints, cosmetics, writing instrument inks, toners, liquid developers, and electrophotographic materials.
[0068]
The ink jet recording method of the present invention is performed by discharging the ink of the present invention onto a recording medium by an ink jet recording apparatus.
[0069]
The ink jet recording method of the present invention can be carried out in the same manner as the conventional ink jet recording method except that the ink of the present invention is used.
[0070]
As the ink jet recording apparatus, substantially all known apparatuses can be used.
[0071]
As the recording medium, those conventionally used can be used, and examples thereof include plain paper, postcards, color copy paper, inkjet paper, plastic sheets, and plastic films.
[0072]
[Example]
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the following, “%” and “parts” represent “% by weight” and “parts by weight”, respectively, unless otherwise specified.
[0073]
In addition, each component used in a present Example is specifically as follows.
[Pigment]
C1: Self-dispersing carbon black
A self-dispersing pigment in which a carboxyl group is bonded to the surface of carbon black via a phenyl group. A self-dispersing carbon black aqueous dispersion with a concentration of 20% filtered through a membrane filter having a pore size of 1.2 μm.
[0074]
C2: Carbon black (for comparative example)
20 parts of carbon black (average particle diameter of about 200 nm) and 40 parts of a water-soluble styrene-acrylic resin aqueous solution (trade name: joncry solution, manufactured by Johnson Polymer Co., Ltd.) were placed in a roll mill and kneaded for 1 hour. After adding 100 parts of polyethylene glycol and kneading for another hour, the mixture was filtered through a membrane filter having a pore size of 1.2 μm to prepare an aqueous dispersion of carbon black.
[0075]
M1: Self-dispersing magenta pigment
This is a self-dispersing magenta pigment in which a magenta pigment (CI Pigment Red 122) is heated in a sulfonated pyridine salt (sulfonating agent) and subjected to sulfonation to introduce a sulfone group on the surface of the pigment. A water dispersion having a concentration of 15% of this self-dispersing magenta pigment is filtered through a membrane filter having a pore size of 1.2 μm.
[0076]
The average particle size, minimum particle size, and maximum particle size of the pigment were measured by a particle size analyzer (trade name: LB500, manufactured by Horiba, Ltd.) using a dynamic scattering method. For pigments with different average particle size, minimum particle size, or maximum particle size, change processing conditions for the pulverization process (change of pulverization conditions) and purification process (selection of salting-out / filtration and ultrafiltration) Manufactured by.
[0077]
(Water-dispersible resin)
P1: Water-dispersible polyester resin emulsion (trade name Vylonal, manufactured by Toyobo Co., Ltd.)
S1: Water-dispersible styrene-acrylic resin emulsion (trade name johncry emulsion, manufactured by Johnson Polymer Co., Ltd.)
Sa: Water-soluble styrene-acrylic resin aqueous solution (joncry solution, for comparative example)
[Surfactant]
Polyoxyethylene nonionic surfactant (trade name: Taditol, manufactured by Union Carbide)
[0078]
Further, the ink obtained in this example was evaluated according to the following evaluation test method.
[Evaluation test method]
Ink was filled in an ink cartridge for evaluation, and recording was performed on a recording paper using an ink jet printer to prepare two types of evaluation samples.
[0079]
As the ink jet printer, an ink jet printer (trade name: CL-700, manufactured by Seiko Epson Corporation) capable of performing high-speed printing using a piezoelectric element as an ink ejection energy source was used.
[0080]
As recording paper, the following three types of plain paper and two types of glossy paper were used.
Plain paper: Trade name 4024 paper, manufactured by Xerox Co., Ltd.
Product name Bond paper, Hammer Mill
Product name: NM paper, manufactured by Sharp Corporation
Glossy paper: Product name Photo-like QP, manufactured by Konica Corporation
Product name Photo glossy paper, manufactured by Sharp Corporation
[0081]
One of the evaluation samples is a 100% solid, 50%, 30%, 10% density evaluation color patch. The other is an evaluation image in which the background is yellow and an ink-colored character is arranged thereon. Yellow, which is the background color of the evaluation image, was recorded using a yellow dye ink having the following composition.
Yellow dye (Acid Yellow 23) 3.0%
Diethylene glycol 10.0%
N-methyl-2-pyrrolidone 6.0%
Diethylene glycol-n-butyl ether 8.0%
Taditol (nonionic surfactant) 1.0%
Water balance
[0082]
(A) Dryability
The plain paper is overlaid on the evaluation color patches printed on the five types of recording paper, and about 9.8 × 10 from above.³Pa (100 g / cm²), The drying time until the ink was not transferred onto the stacked plain paper was measured, and evaluated according to the following criteria.
○: Less than 15 seconds
Δ: Less than 15-30 seconds
×: 30 seconds or more
[0083]
(B) Breathability
The dot diameter and dot shape of evaluation color patches printed on three types of plain paper were measured and evaluated according to the following criteria.
[0084]
(Double-circle): The dot diameter is 3.5 times or less compared with the true spherical equivalent diameter, the shape is also a beautiful circle, and the bleeding (unevenness) of the edge portion is hardly observed in all three types of recording materials.
[0085]
◯: The dot diameter is 4 times or less than the true sphere equivalent diameter, the shape is almost circular, and the edge portion is slightly blurred (unevenness) depending on the recording material, but is within the allowable range.
[0086]
(Triangle | delta): The dot diameter exceeds 4 times compared with a true sphere conversion diameter, a shape also shows an indefinite shape, and the bleeding (unevenness | corrugation) of an edge part is recognized depending on the recording material, and is outside an allowable range.
[0087]
X: The dot diameter is 5 times or more compared to the true spherical equivalent diameter, the shape is indefinite, and the bleeding (unevenness) of the edge portion is severe in all three types of recording materials.
[0088]
(C) Color mixing
For the evaluation images printed on three types of plain paper, the color mixture of the yellow background and the ink color of the character was visually observed and evaluated according to the following criteria.
A: Almost no color mixing is observed in all three recording materials.
○: Some color mixing is recognized depending on the recording material, but it is within the allowable range.
Δ: Depending on the recording material, a considerable color mixture is recognized, which is outside the allowable range.
X: Vigorous color mixing is observed in all three types of recording materials.
[0089]
(D) Optical density
Color patches for evaluation printed on three types of plain paper were printed, and 100% solid portions were measured using a spectrocolorimetric densitometer (trade name: X-Rite 938, manufactured by X-Rite). evaluated.
A: All the recording materials exhibit high optical density and a wide color reproduction range.
◯: A relatively high optical density is shown in all the recording materials and is within an allowable range. X: Depending on the recording material and the color, a low optical density is shown, which is outside the allowable range.
[0090]
(E) show-through property
The evaluation color patches and evaluation images printed on three types of plain paper were visually observed from the back side, and the degree of ink breakthrough was evaluated according to the following criteria.
A: There is no show-through in all recording materials.
◯: Although a slight back-through is recognized depending on the recording material, it is within an allowable range.
X: Depending on the recording material, there is a considerable amount of show-through, which is outside the allowable range.
[0091]
(F) Fixability
Images for evaluation were printed on two types of glossy papers, and after 24 hours, they were rubbed with an eraser a certain number of times to evaluate how the ink-colored characters peeled according to the following criteria.
○: Slight traces are recognized, but it is within the allowable range.
(Triangle | delta): A rubbing trace is recognized and it is outside an allowable range.
X: How to peel off is severe.
[0092]
(G) Discharge stability
Immediately after preparation of the ink, the ink cartridge is filled, and after printing continuously for 10 minutes, the printing is stopped, left in an environment of 40 ° C. and 25% RH for 72 hours, and the nozzle is cleaned before printing. The evaluation was based on the following criteria.
○: Nozzle cleaning operation was performed less than 5 times, and printing equivalent to the initial printing was achieved.
X: Good printing could not be performed in the initial stage, or printing equivalent to the initial stage could not be performed even when the nozzle cleaning operation was performed five times.
[0093]
(H) Storage stability
60 cc of ink was placed in a test screw tube bottle and left for 1 month in an environment of −10 ° C. and 50 ° C. to check for the presence of sediment.
○: No sediment
×: There is sediment
[0094]
(I) Overall evaluation
The evaluation criteria for comprehensive evaluation are as follows.
(Double-circle): In all the evaluations, it is more than (circle) and evaluation of (double-circle) is recognized by many.
◯: In all evaluations, it is ◯ or more and there is no or little evaluation of ◎.
Δ: Δ is recognized in the evaluation.
X: x is recognized in evaluation.
[0095]
  Reference Examples 1-4And Comparative Examples 1 to 4
  After sequentially adding water, a water-dispersible resin, an organic solvent and a surfactant to the pigment (water dispersion) described in Table 1 at a ratio (%) described in Table 2, the mixture was stirred at 40 ° C. for 2 hours, Return to room temperature and let stand for 1 day, filter through a membrane filter with a pore size of 0.9 μm,Reference Examples 1-4Ink of Comparative Examples 1 to 4 was prepared.
[0096]
In Table 2, the pigment and the water-dispersible resin are shown as solid contents.
[0097]
[Table 1]

[0098]
    Reference Examples 1-4For the inks of Comparative Examples 1 to 4, (a) drying property, (b) bleeding property, (d) optical density and (g) ejection stability were evaluated according to the evaluation test method described above, and (i) synthesis. Evaluation was performed. The results are shown in Table 2.
[0099]
[Table 2]

[0100]
  From Table 2Reference examples 1 to 4However, it satisfies all of the characteristics of dryness, bleeding, optical density and ejection stability, while using water-soluble resin.RatioComparative Example 14 is,Reference Examples 1-4It is clear that all performance is insufficient compared to.
[0101]
  Reference Example 5And Comparative Example 5
  Except for using the following ingredients in the following proportions (%)Reference example 1LikeReference exampleAnd inks of comparative examples were prepared.
[0102]
-Self-dispersing carbon black Cb1 listed in Table 3 (%)
(Average particle diameter 300 nm, minimum particle diameter 10 nm, maximum particle diameter 600 nm)
-Water-dispersible resin P1 or S1 as described in Table 3 (%)
・ Glycerin 15.0%
・ Diethylene glycol 15.0%
・ 1,2-hexanediol 10.0%
・ Triethylene glycol monobutyl ether 10.0%
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0103]
In Table 3, “solid content” means the solid content (%) which is the total amount of the self-dispersing carbon black C1b and the resin content of the water-dispersible resin P1 or S1. The “weight ratio” means the content (parts) of the resin component of the water-dispersible resin with respect to 100 parts of the self-dispersing carbon black C1b.
[0104]
  ObtainedReference Example 5For the ink of Comparative Example 5, (b) bleeding, (c) color mixing, (d) optical density, (f) fixability, (g) ejection stability, and (h) storage in accordance with the evaluation test method described above. Stability was evaluated and (i) comprehensive evaluation was performed. The results are shown in Table 3.
[0105]
[Table 3]

[0106]
In addition, No. of Comparative Example 5 No. 14 and 15 were not evaluated since the overall evaluation x was determined at the stage when the ejection stability and the storage stability were evaluated.
[0107]
  referenceExample 6 and Comparative Example 6
  Except for using the following ingredients in the following proportions (%)referenceSimilar to Example 1,Reference exampleAnd inks of comparative examples were prepared.
[0108]
Self-dispersing magenta pigment M1a listed in Table 4 (%)
(Average particle size 220 nm, minimum particle size 10 nm, maximum particle size 420 nm)
-Water dispersible resin P1 or S1 listed in Table 4 (%)
・ Glycerin 15.0%
・ Propylene glycol 15.0%
・ 1,2-hexanediol 10.0%
・ Tetraethylene glycol monobutyl ether 10.0%
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0109]
In Table 4, “solid content” means the solid content (%) which is the total amount of the self-dispersing magenta pigment M1a and the resin content of the water-dispersible resin P1 or S1. The “weight ratio” means the resin content (parts) of the water-dispersible resin with respect to 100 parts of the self-dispersing magenta pigment M1a.
[0110]
  Reference Example 6For the ink of Comparative Example 6, (b) bleeding, (c) color mixing, (d) optical density, (f) fixability, (g) ejection stability and (h) Storage stability was evaluated, and (i) comprehensive evaluation was performed. The results are shown in Table 4.
[0111]
[Table 4]

[0112]
In addition, the comparative example 6 No. For Nos. 12 and 13, since the overall evaluation x was determined when the ejection stability and the storage stability were evaluated, no other evaluation items were performed.
[0113]
From Tables 3 and 4, the following can be seen.
1) The content of the self-dispersing pigment is preferably selected from the range of 0.5 to 12%. When the self-dispersing pigment concentration is lower than 0.5%, the optical density is remarkably lowered and falls outside the allowable range. If it is higher than 12%, the pigment cannot be used because it starts to aggregate and settle in the ink.
2) The solid content, which is the total amount of the self-dispersing pigment and the resin component of the water-dispersible resin, must be 1.0 to 20%. When the solid content is lower than 1.0%, bleeding, color mixing, and the like increase, and a good recorded image cannot be obtained. If it is higher than 20%, good ejection stability cannot be obtained.
3) It is essential that the content ratio of the self-dispersing pigment and the water-dispersible resin is 20 to 500 parts of water-dispersible resin (in terms of resin) with respect to 100 parts of the self-dispersing pigment. When the amount of the water-dispersible resin is less than 20 parts, the fixability is lowered and color mixing tends to occur. When it is more than 500 parts, the optical density is lowered.
[0114]
  Example 1, Reference Example 7And Comparative Example 7
  Except for using the self-dispersing carbon black or self-dispersing magenta pigment shown in Table 5 and using each component in the ratio (%) shown in Table 6,Reference example 1In the same manner as the ink of the present invention, Reference example inkAnd inks of comparative examples were prepared.
[0115]
  Example 1, Reference Example 7For the ink of Comparative Example 7, according to the evaluation test method described above, (b) bleeding property, (c) color mixing property, (d) optical density, (e) show-through property, (g) ejection stability and (h ) Storage stability was evaluated, and (i) comprehensive evaluation was performed. The results are also shown in Table 6.
[0116]
In Table 6, the numbers in parentheses for the self-dispersing pigments are the average particle diameter of each pigment.
[0117]
[Table 5]

[0118]
[Table 6]

[0119]
In addition, No. of Comparative Example 7 In No. 2, since the overall evaluation x was determined at the stage of evaluating the ejection stability and the storage stability, no other evaluation items were carried out.
[0120]
From Table 6, it is clear that the self-dispersing pigment must have an average particle size in the range of 200 to 500 nm. When the average particle diameter is smaller than 200 nm, bleeding, color mixture and show-through occur. When the average particle diameter is larger than 500 nm, pigment aggregation and sedimentation occur, which causes problems in the storage stability and ejection stability of the ink.
[0121]
  Example 2And Comparative Example 8
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1In the same manner, inks of the present invention and comparative inks were prepared.
[0122]
・ Self-dispersing carbon black C1c 3.0%
(Average particle diameter 500 nm, minimum particle diameter 10 nm, maximum particle diameter 1 μm)
・ Water-dispersible polyester resin P1 4.0%
・ Alkanediols (1) to (5) listed in Table 7 (%)
・ Glycerin 15.0%
・ Diethylene glycol 10.0%
・ Triethylene glycol monobutyl ether 10.0%
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0123]
  Obtained aboveExample 2(B) Bleeding property, (c) Color mixing property, (e) Back-through property, (g) Ejection stability and (h) Storage stability of the ink of Comparative Example 8 and the ink of Comparative Example 8 And (i) comprehensive evaluation was performed. The results are shown in Table 7.
[0124]
The alkanediols (1) to (5) are specifically as follows.
(1) 1,2-hexanediol
(2) 1,2-pentanediol
(3) 1,2-butanediol
(4) 1,6-hexanediol
(5) 1,5-pentanediol
[0125]
[Table 7]

[0126]
In addition, the comparative example 8 No. For 4 and 5, since the overall evaluation x was determined when the ejection stability and the storage stability were evaluated, the other evaluation items were not carried out.
[0127]
  Reference Example 8And Comparative Example 9
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1LikeReference exampleInks and comparative inks were prepared.
[0128]
-Self-dispersing magenta pigment M1a 3.0%
(Average particle size 290 nm, minimum particle size 10 nm, maximum particle size 560 nm)
・ Water-dispersible polyester resin P1 4.0%
・ Alkanediols (1) to (5) listed in Table 8 (%)
・ Glycerin 15.0%
・ Propylene glycol 10.0%
・ Tetraethylene glycol monobutyl ether 10.0%
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0129]
  Obtained aboveReference Example 8(B) Bleeding property, (c) Color mixing property, (e) Back-through property, (g) Ejection stability and (h) Storage stability of the ink of Comparative Example 9 and the ink of Comparative Example 9 And (i) comprehensive evaluation was performed. The results are shown in Table 8.
[0130]
The alkanediols (1) to (5) in Table 8 are the same as in Table 7.
[0131]
[Table 8]

[0132]
In addition, No. of Comparative Example 9 For 4 and 5, since the overall evaluation x was determined when the ejection stability and the storage stability were evaluated, the other evaluation items were not carried out.
[0133]
From Tables 7 and 8, when 1,2-hexanediol, 1,2-pentanediol or 1,2-butanediol is used as the alkanediol, the dispersibility of the pigment / resin is increased, and aggregation / sedimentation is achieved. It is clear that good storage stability and ejection stability can be obtained even in an ink using a pigment having a function of preventing and having a large average particle diameter. Further, the content of alkanediols is preferably 5 to 30% by weight, and if it is lower than 5% by weight, there is a problem in the storage stability and ejection property of the ink, and if it is higher than 30% by weight, bleeding / color mixing characteristics are exhibited. Decreases and strikethrough occurs.
[0134]
  Example 3And Comparative Example 10
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1In the same manner, inks of the present invention and comparative inks were prepared.
[0135]
・ Self-dispersing carbon black C1c 3.0%
・ Water-dispersible polyester resin P1 4.0%
・ 1,2-hexanediol 5.0%
・ Glycerin (Solvent 6 in Table 9) Listed in Table 9 (%)
Diethylene glycol (Solvent 7 in Table 9) Listed in Table 9 (%)
・ Triethylene glycol monobutyl ether 5.0%
・ Nonionic surfactant (Taditol) 1.0%
-Water balance (described in Table 9,%)
[0136]
  Obtained aboveExample 3(B) Bleeding property, (c) Color mixing property, (g) Ejection stability and (h) Storage stability of the ink of Comparative Example 10 and the ink of Comparative Example 10 were further evaluated. ) Comprehensive evaluation was performed. The results are shown in Table 9.
[0137]
[Table 9]

[0138]
No. of Comparative Example 10 As for 2 and 4-6, since comprehensive evaluation x was determined at the stage when ejection stability and storage stability were evaluated, other evaluation items were not carried out.
[0139]
  Reference Example 9And Comparative Example 11
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1LikeReference exampleInks and comparative inks were prepared.
[0140]
-Self-dispersing magenta pigment M1b 3.0%
・ Water-dispersible polyester resin P1 4.0%
・ 1,2-hexanediol 5.0%
Glycerin (solvent (6) in Table 10) listed in Table 10 (%)
Propylene glycol (Solvent 7 in Table 10) Listed in Table 10 (%)
・ Tetraethylene glycol monobutyl ether 5.0%
・ Nonionic surfactant (Taditol) 1.0%
・ Balance of water (Described in Table 10,%)
[0141]
  Obtained aboveReference Example 9Ink and comparative example11In this ink, according to the above-described evaluation test method, (b) bleeding property, (c) color mixing property, (g) ejection stability and (h) storage stability were evaluated, and (i) comprehensive evaluation was performed. . The results are shown in Table 10.
[0142]
[Table 10]

[0143]
No. of Comparative Example 11 As for 2 and 4-6, since comprehensive evaluation x was determined at the stage when ejection stability and storage stability were evaluated, other evaluation items were not carried out.
[0144]
From Table 9 and Table 10, it is essential that the content of the organic solvent is 30 to 70%, and it is preferable to contain 20% or more of an organic solvent selected from glycerin, diethylene glycol, propylene glycol or a mixture thereof. I understand that. When the content of the organic solvent is less than 30%, ejection failure occurs. If it exceeds 70%, the water content will be too low, the dispersibility of the self-dispersing pigment and water-dispersible resin dispersed in water will be reduced, causing aggregation / sedimentation, and problems with ink storage stability and ejection properties. Occurs. It can be seen that the water content is preferably 20% or more of the total amount of ink.
[0145]
  Example 4And Comparative Example 12
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1In the same manner, inks of the present invention and comparative inks were prepared.
[0146]
・ Self-dispersing carbon black C1c 3.0%
・ Water-dispersible polyester resin P1 4.0%
・ Glycerin 15.0%
・ Diethylene glycol 10.0%
・ 1,2-hexanediol 10.0%
Alkylene glycol monoalkyl ethers listed in Table 11 (%)
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0147]
  Example 4In the ink of Comparative Example 12 and the ink of Comparative Example 12, (a) drying property, (b) bleeding property, (c) color mixing property and (e) show-through were evaluated according to the above-described evaluation test method, and (i) synthesis Evaluation was performed. The results are shown in Table 11.
[0148]
[Table 11]

[0149]
  Reference Example 10And Comparative Example 13
  Except for using the following ingredients in the proportions (%) shown below,Reference example 1LikeReference exampleInks and comparative inks were prepared.
[0150]
-Self-dispersing magenta pigment M1b 3.0%
・ Water-dispersible polyester resin P1 4.0%
・ Glycerin 15.0%
・ Propylene glycol 10.0%
・ 1,2-hexanediol 10.0%
Alkylene glycol monoalkyl ethers listed in Table 12 (%)
・ Nonionic surfactant (Taditol) 1.0%
・ Water balance
[0151]
  Reference Example 10In the ink of Comparative Example 13 and the ink of Comparative Example 13, (a) drying property, (b) bleeding property, (c) color mixing property and (e) show-through were evaluated according to the above-described evaluation test method, and (i) synthesis Evaluation was performed. The results are shown in Table 12.
[0152]
[Table 12]

[0153]
From Tables 11 and 12, it can be seen that it is preferable to contain 5 to 20% of the total amount of the alkylene glycol alkyl ether. When the alkylene glycol alkyl ether is lower than 5%, the drying property of the ink is poor and problems such as color mixing occur. If it is higher than 20%, the permeability of the ink becomes too high, resulting in show-through and bleeding. Further, as the alkylene glycol alkyl ether, dipropylene glycol-n-propylene ether, diethylene glycol-n-butyl ether, triethylene glycol-n-butyl ether, tetraethylene glycol-n-butyl ether, propylene glycol-n-butyl ether, dipropylene glycol It can be seen that -n-butyl ether and the like are preferable.
[0154]
【The invention's effect】
According to the present invention, there is no color bleeding, color mixing, show-through, etc., a high-optical density recording image with good fixability can be formed, storage stability and ejection stability are excellent, and ink liquid Provided is a pigment ink for ink-jet recording which can cope with finer droplets.
[0155]
According to the present invention, the storage stability of the ink of the present invention is further improved by selecting the content of 1,2-alkanediol from a specific range of 5 to 30% by weight.
[0156]
According to the present invention, the storage stability of the ink of the present invention is further improved by using the above-mentioned specific 1,2-alkanediol.
[0157]
According to the present invention, the discharge stability of the ink of the present invention is further improved by using the above specific solvent other than 1,2-alkanediol in an amount of 20 wt% or more.
[0158]
According to the present invention, the organic solvent other than 1,2-alkanediol is used in a specific amount of 5 to 20% by weight of the above specific solvent, thereby further increasing the permeability of the ink of the present invention to the recording medium. Range.
[0159]
According to the present invention, the storage stability of the ink of the present invention is further improved by using water in an amount of 20% by weight or more.
[0160]
According to the present invention, by using a specific water-dispersible resin, it is possible to further suppress the occurrence of color bleeding in the recorded image by the ink of the present invention and to form a recorded image having a higher optical density. it can.
[0161]
According to the present invention, by selecting the content of the self-dispersing pigment from a specific range of 0.5 to 12% by weight, the storage stability of the ink of the present invention is further improved and the recorded image has a higher optical density. Can be formed.
[0162]
According to the present invention, by using the ink of the present invention and recording with an ink jet printer, recording can be performed smoothly and a high-quality recorded image can be formed.

Claims (10)

Containing at least a self-dispersing pigment, a water-dispersible resin, water and an organic solvent, the self-dispersing pigment has an average particle diameter of more than 300 nm and not more than 500 nm , and the self-dispersing pigment and the water-dispersing resin in the ink, The content of the organic solvent in the ink having a solid content of 1.0 to 20% by weight of the total amount of the ink and containing 20 to 500 parts by weight of the water-dispersible resin with respect to 100 parts by weight of the self-dispersing pigment Is 30 to 70% by weight of the total amount of the ink, and the organic solvent contains at least 1,2-alkanediol.   2. The ink according to claim 1, wherein 1,2-alkanediol is contained in an amount of 5 to 30% by weight based on the total amount of the ink.   The 1,2-alkanediol is one or a mixture of two or more selected from 1,2-butanediol, 1,2-pentanediol and 1,2-hexanediol. The ink described.   2. The ink according to claim 1, further comprising 20% by weight or more of an organic solvent which is one or a mixture of two or more selected from glycerin, diethylene glycol and propylene glycol. 5. The ink according to claim 4, wherein the organic solvent which is a mixture of glycerin and diethylene glycol contains 40% by weight of the total amount of the ink.   2. The ink according to claim 1, further comprising 5 to 20% by weight of an organic solvent which is one or a mixture of two or more selected from alkylene glycol alkyl ethers.   The ink according to claim 1, wherein water is contained in an amount of 20% by weight or more based on the total amount of the ink.   2. The ink according to claim 1, wherein the water dispersible resin is one or a mixture of two or more selected from polyester resins and styrene-acrylic resins.   The ink according to claim 1, wherein the self-dispersing pigment is contained in an amount of 0.5 to 12% by weight based on the total amount of the ink. An ink jet recording method characterized by forming an image on a recording medium by ejecting an ink jet recording pigment ink according to any one of claims 1-9.