JP4324979B2 - Ink for inkjet recording - Google Patents

Description

【００２６】
【表２】

なお表１．表２．中、

である。
【００２７】
【実施例２】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（２）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
パラメチルスチレン−メタクリル酸ブチル共重合体微粒子（不揮発分換算）５．０wt％
水 残
ここにパラメチルスチレン−メタクリル酸ブチル共重合体微粒子はパラメチルスチレン７５wt％、メタクリル酸ブチル２０wt％、ジビニルベンゼン５wt％からなるソープフリー乳化重合により得られた共重合体樹脂粒子水分散体であり、
平均粒子径 ０．４５μｍ
樹脂比重 １．０２
最低造膜温度 １０２℃
ビカット軟化点 ９５℃
である。
本樹脂は、メタノール、エタノール、イソプロパノール、エチレングリコール、ニトリルトリエタノールに対して溶解しなかった、ただしメタノールに対し若干膨潤が観察された。不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においては最低造膜が約４℃低下したが、粒子径には検出できる程の変化がないため低級アルコールによる膨潤性は低いと判断された。
【００２８】
【実施例３】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（３）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
アイオノマー樹脂微粒子Ｓ−２００ （不揮発分換算）５．０wt％
水 残
ここにアイオノマー樹脂微粒子はアルカリ金属イオンにより部分的イオン架橋されたエチレン−メタクリル酸共重合体（エチレン８０〜９０wt％、メタクリル酸１０〜２０wt％）からなりソープフリー乳化手法により得られた水分散体であり、ケミパールＳ−２００として三井石油化学社より上市されているものであり、
平均粒子径 ０．４３μｍ
樹脂比重 ０．９５
最低造膜温度 ８５℃
ビカット軟化点 ５７℃
である。
【００２９】
本樹脂はメタノール、エタノール、イソプロピルアルコール、エチレングリコール、ニトリルトリエタノールに対して溶解せず、膨潤している様子も観察されなかった。さらに不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においても最低造膜には変化がなく、粒子径にも変化がないため低級アルコールによる膨潤性は事実上ないと判断された。
【００３０】
【実施例４】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（４）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
アイオノマー樹脂微粒子Ｓ−３００ （不揮発分換算）２．０wt％
水 残
ここにアイオノマー樹脂微粒子はアルカリ金属イオンにより部分的イオン架橋されたエチレン−メタクリル酸共重合体（エチレン８０〜９０wt％、メタクリル酸１０〜２０wt％）からなりソープフリー乳化手法により得られた水分散体であり、ケミパールＳ−３００として三井石油化学社より上市されているものであり、
平均粒子径 ０．５３μｍ
樹脂比重 ０．９５
最低造膜温度 ９４℃
ビカット軟化点 ６７℃
である。本樹脂は実施例３に用いられたアイオノマー樹脂と同様、低級アルコールによる膨潤性は事実上ないと判断された。
【００３１】
【実施例５】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（５）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
変性アイオノマー樹脂微粒子ＳＡ−１００（不揮発分換算）２．０wt％
水 残
ここに変性アイオノマー樹脂微粒子はアルカリ金属イオンにより部分的イオン架橋されたエチレン−メタクリル酸共重合体（エチレン８０〜９０wt％、メタクリル酸１０〜２０wt％）にさらにスチレンをグラフトしたグラフト共重合体からなるソープフリー乳化手法により得られた水分散体であり、ケミパールＳＡ−１００として三井石油化学社より上市されているものであり、
平均粒子径 ０．７５μｍ
樹脂比重 １．００
最低造膜温度 ７０℃
ビカット軟化点 ５５℃
である。本樹脂は、メタノール、エタノール、イソプロパノール、エチレングリコール、ニトリルトリエタノールに対して溶解しなかった、ただしメタノールに対し若干膨潤が観察された。不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においては最低造膜が約２℃低下したが、粒子径には検出できる程の変化がないため低級アルコールによる膨潤性は低いと判断された。
【００３２】
【比較例１】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（６）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
水 残
本試作インクは樹脂粒子を含まない所謂典型的な有機顔料微分散型インクである。
【００３３】
【比較例２】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（７）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
塩化ビニリデン共重合体ラテックス （不揮発分換算）５．０wt％
水 残
ここに塩化ビニリデン共重合体ラテックスは塩化ビニリデン−塩化ビニル共重合体の脂肪族石鹸を用いた乳化分散ラテックスである。
平均粒子径 ０．１５μｍ
樹脂比重 １．３６
最低造膜温度 １３５℃
ビカット軟化点 １２５℃
である。本樹脂は実施例１と同様の評価の結果、低級アルコールによる膨潤性は低いと判断された。
【００３４】
【比較例３】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（８）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
塩化ビニリデン共重合体ラテックス （不揮発分換算）５．０wt％
水 残
ここに塩化ビニリデン共重合体ラテックスは比較例１と同様、塩化ビニリデン−塩化ビニル共重合体の脂肪族石鹸を用いた乳化分散ラテックスである。
平均粒子径 ０．４５μｍ
樹脂比重 １．３６
最低造膜温度 １３５℃
ビカット軟化点 １２５℃
であり比較例１に対して粒子径が大となっている。本樹脂は実施例１と同様の評価の結果、低級アルコールによる膨潤性は低いと判断された。
【００３５】
【比較例４】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（９）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
スチレン−ブタジエン共重合体ラテックス（不揮発分換算）５．０wt％
水 残
ここにスチレン−ブタジエン共重合体ラテックスはスチレン２５wt％を含む共重合体の脂肪族石鹸を用いた乳化分散ラテックスである。
平均粒子径 １．１０μｍ
樹脂比重 ０．９７
最低造膜温度 ２４℃
ビカット軟化点 １０℃
である。本樹脂は、メタノール、エタノール、イソプロパノールに溶解した。エチレングリコール、ニトリルトリエタノールに対して溶解しなかった。不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においては最低造膜は２４℃以上低下、すなわち氷点以下にならない場合には自然乾燥により造膜した。したがって膨潤性は非常に高い判断された。
【００３６】
【比較例５】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（10）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
ポリメチルメタクリレートラテックス （不揮発分換算）５．０wt％
水 残
ここにポリメチルメタクリレートラテックスはソープフリー乳化重合により得られた単分散性の高いラテックス粒子である。
平均粒子径 ０．５２μｍ
樹脂比重 １．１９
最低造膜温度 １２０℃
ビカット軟化点 １１０℃
である。本樹脂は、メタノール、エタノール、イソプロパノール、エチレングリコール、ニトリルトリエタノールに対して溶解はしなかったが、メタノール、イソプロパノールに対して若干表面が軟化膨潤のきざしを示した。不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においては最低造膜は１２℃低下した。膨潤性はそれほど高くないが若干は認められるものとされた。
【００３７】
【比較例６】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（11）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
アクリル系共重合体ラテックス （不揮発分換算）５．０wt％
水 残
ここにアクリル系共重合体ラテックスはメチルメタクリレート、エチルメタクリレート、ブチルメタクリレートからなる乳化重合により得られた共重合体ラテックス粒子である。
平均粒子径 ０．４５μｍ
樹脂比重 １．０８
最低造膜温度 ８４℃
ビカット軟化点 ８０℃
である。本樹脂は、エタノール、エチレングリコール、ニトリルトリエタノールに対して溶解はしなかったが、メタノール、イソプロパノールに対して若干溶解性が観察された。不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においては最低造膜は３０℃近く低下し、膨潤性は高いと判断された。
【００３８】
【比較例７】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。ただし１．０μｍメンブレンフィルターによる濾過工程は省略した。結果を表１．表２．に示す。
試作インク（12）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
ポリオレフィン微粒子Ｗ−５００ （不揮発分換算）５．０wt％
水 残
ここにポリオレフィン微粒子は低分子量ポリオレフィン（主にポリエチレン）からなりソープフリー乳化手法により得られた水分散体であり、ケミパールＷ−５００として三井石油化学社より上市されているものであり、
平均粒子径 ２．５０μｍ
樹脂比重 ０．９２
最低造膜温度 ９０℃
ビカット軟化点 ３８℃
である。本樹脂はメタノール、エタノール、イソプロピルアルコール、エチレングリコール、ニトリルトリエタノールに対して溶解せず、膨潤している様子も観察されなかった。さらに不揮発分濃度を２０wt％に調製した水分散体１００wt部にイソプロピルアルコール１０wt部を添加した場合においても最低造膜には変化がなく、粒子径にも変化がないため低級アルコールによる膨潤性は事実上ないと判断された。
【００３９】
【比較例８】
下記組成のインクジェット記録用インクを実施例１と同様の手順にて調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（13）
水溶性染料 Ｃ. Ｉ. Ｄｉｒｅｃｔ Ｂｌｕｅ ８６ 精製品 １．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
水 残
本試作インクは樹脂粒子を含まない所謂典型的な水溶性染料型インクである。
【００４０】
【実施例６】
有機顔料の水分散体を「Ｌｅｖａｎｙｌ Ｙｅｌｌｏｗ １０ＧＺ」（ＢＡＹＥＲ社製、平均粒子径０．０６μｍ、ノニオン系分散剤を使用して微分散したＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ ３）に代え、以下実施例１と同様の手順にて試作インクを調製し、同様の評価を行なった。結果を表１．表２．に示す。
試作インク（14）
有機顔料 （顔料分換算）１０．０wt％
エチレングリコール ５．０wt％
イソプロピルアルコール ０．８wt％
ニトリルトリエタノール ０．２wt％
アイオノマー樹脂微粒子Ｓ−２００ （不揮発分換算）５．０wt％
水 残
ここにアイオノマー樹脂微粒子は実施例３で用いたものと同じである。
【００４１】
【実施例７】
有機顔料の水分散体を「Ｌｅｖａｎｙｌ Ｃａｒｍｉｎ ＧＺ」（ＢＡＹＥＲ社製、平均粒子径０．０６μｍ、ノニオン系分散剤を使用して微分散したＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ ９５）に代え、それ以外は実施例６と同様の組成と手順にとして試作インク（15）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４２】
【実施例８】
有機顔料の水分散体を「Ｌｅｖａｎｙｌ Ｖｉｏｌｅｔ ＢＮＺ」（ＢＡＹＥＲ社製、平均粒子径０．０６μｍ、ノニオン系分散剤を使用して微分散したＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｖｉｏｌｅｔ ２３）に代え、それ以外は実施例６と同様の組成と手順にとして試作インク（16）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４３】
【実施例９】
「Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２」２０重量部、スチレン−マレイン酸共重合樹脂の部分エステル化物（酸価２０００eq/ton）の水溶液（不揮発分２０wt％）１０重量部、イオン交換水７０重量部をアトライターに仕込み、約３時間分散処理を行なった。得られた分散体を５Ｂろ紙にて濾過した後にメンブレンフィルター１．０μｍ、メンブレンフィルター０．４μｍ、メンブレンフィルター０．２μｍと濾過し、最終的に平均粒子径０．０８μｍの顔料水分散体を得た。このようにして得られた顔料水分散体を用い、それ以外は実施例６と同様の組成と手順にとして試作インク（17）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４４】
【実施例１０】
有機顔料を「Ｐｅｒｍａｎｅｎｔ Ｒｕｂｉｎｅ Ｆ６Ｂ（Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １８４）」（ＨＯＥＣＨＳＴ社製）に変えた以外は実施例９と同様の組成、手順にて試作インク（18）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４５】
【実施例１１】
有機顔料を「Ｐｅｒｍａｎｅｎｔ Ｐｉｎｋ Ｆ３Ｂ」（ＨＯＥＣＨＳＴ社製）に変えた以外は実施例９と同様の組成、手順にて試作インク（19）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４６】
【実施例１２】
有機顔料を「Ｐａｌｉｏｔｏｌ Ｙｅｌｌｏｗ Ｓ１１５５（Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １８５」（ＢＡＳＦ社製）に変えた以外は実施例９と同様の組成、手順にて試作インク（20）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４７】
【実施例１３】
有機顔料を「Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １７」に変えた以外は実施例９と同様の組成、手順にて試作インク（21）を得た。以下実施例１と同様の評価を行い、結果を表１．表２．に示す。
【００４８】
【発明の効果】
以上述べてきたように、本発明のインクジェット記録インクは高い高品位な記録画像、印字が可能であるとともにノズル目詰まりに対する耐性が高く、また長期間静置保存した場合にも安定な優れた特性を有する物である。[0001]
[Industrial application fields]
The present invention includes printers for computers, word processors, facsimiles, digital copying machines, CAD output plotters, pop (POP) writers, large signboards, poster printers, etc., to printing of fabrics, carpets, wallpaper, etc. The present invention relates to inks for ink jet recording that have been widely used, and more specifically to inks using finely dispersed particles of organic pigment as a recording material.
[0002]
[Prior art]
Inkjet recording technology is non-contact recording, and has a wide range of applications from small recording devices to very large devices, and is relatively easy to color, so it is used in a wide range from OA to industrial use. .
Ink jet recording is roughly classified into a continuous jet type and an on-demand jet type from its form. The former is mainly used for industrial printers, and the latter is mainly used for small OA and portable printers. In particular, demand for on-demand small printers using the thermal bubble jet method or the piezo method has been rapidly increasing in recent years.
Inks used for industrial printers are mainly solvent-based inks due to the demand for quick drying, and water-based inks are mainly used for OA and portable printers in consideration of the use environment.
[0003]
(Water-soluble dye ink)
Many water-based inks are water-soluble dye-type inks. Water-soluble dye-type inks are mainly used in aqueous solutions of water-soluble dyes, which are classified as acid dyes, direct dyes, and some food dyes, and as interfaces for the preparation of glycols, alkanolamines, surface tension, etc. as humectants. A small amount of activator, alcohol or the like is added. There are some patent proposals that add a water-soluble resin component as a binder component, but it is not practically used due to concerns about nozzle clogging.
These water-soluble dye type inks are most commonly used because of their high reliability against nozzle clogging. However, such a water-soluble dye-type ink is easy to bleed on the recording paper because it is an aqueous solution of the dye, and conversely, because it is prepared so as to penetrate the recording paper quickly from the need to increase the apparent drying speed, The recording quality has been reduced. It is also obvious that the water resistance is poor because it is a water-soluble dye. Furthermore, water-soluble dyes that have only penetrated into the recording paper and have been dry-fixed cannot be said to be “dyed” and have a very low light fastness.
[0004]
(Resin fine particle addition-water-soluble dye type ink)
As a measure for solving the problems of the water-soluble dye ink as described above, it has long been studied to add resin fine particles such as emulsion and latex.
Japanese Patent Application Laid-Open No. 55-18418 adds a latex which is “a kind of colloidal solution in which components such as rubber and resin are dispersed in water in the form of fine particles (particle size of about 0.01 to several μm) with an emulsifier”. There are proposals for ink jet recording inks. As latex that is preferably used,
Styrene-butadiene copolymer latex,
Acrylonitrile-butadiene copolymer latex,
Polychloroprene latex,
Vinylpyridine-styrene-butadiene latex,
Butyl rubber latex,
Polybutadiene latex,
Polyisoprene latex,
Polysulfide rubber latex,
Synthetic rubber latex such as
Acrylic ester latex,
Styrene-butadiene resin latex,
Vinyl acetate latex,
Vinyl chloride latex,
Vinylidene chloride latex,
Synthetic resin latexes such as are exemplified.
[0005]
In the proposal, the particle diameter of latex particles that can be added is said to be in the range of about 0.01 to several μm. However, when the particle diameter is less than 0.2 μm, the effect of preventing ink blur on the recording paper is insufficient, and high recording quality cannot be obtained. On the other hand, when the particle diameter is 1.0 μm or more, the nozzles are frequently clogged, making it difficult to use from the viewpoint of reliability. Therefore, the range that can be practically used is considered to be approximately 0.2 to 1.0 μm.
When such resin fine particles are added to the ink, it is necessary to pay attention to sedimentation or flying due to the difference in specific gravity of the particles and specific gravity of the medium. In the case of water-based ink, it is difficult for the specific gravity of the medium to depart greatly from 1.0. In the case of fine particles having a size of about 0.2 μm or more, the effect of gravity is larger than the diffusion force of particles due to Brownian motion, and therefore the difference between the particle specific gravity and the medium specific gravity is 0.1 or less, preferably 0. It is necessary to suppress it to about 07 or less.
The specific gravity of the synthetic rubber-based latex exemplified in the patent proposal is approximately in the range of 0.9 to 1.0, and most of the synthetic rubber has an unsaturated double bond in the molecule, although this condition is met to some extent. There are problems in terms of light resistance and weather resistance. Further, when unsaturated bonds are reduced by vulcanization, the fixing of the particles onto the recording paper is hindered, resulting in a problem in recording quality. Further, if vulcanized excessively, the specific gravity becomes 1.1 or more, which causes a problem of sedimentation. Furthermore, such synthetic rubber latex has a low glass transition temperature, so it is easy to form a film at room temperature, and when it is dried at the tip of an inkjet nozzle, the nozzle is likely to be clogged, and the dried product is flexible and somewhat sticky. It is very difficult to remove it.
[0006]
The specific gravity of the synthetic resin latex exemplified in the patent is 1.1 or more, particularly in the case of a synthetic resin containing a halogen element, the specific gravity is close to 1.3 to 1.5. Sedimentation occurs in all areas.
Furthermore, as can be said for these latexes in general, many of the emulsifiers used in producing the latex tend to promote foaming of the ink, and there are many problems because the surface tension is lowered more than necessary.
Japanese Patent Laid-Open No. 54-146109 proposes a water-soluble dye-type ink to which vinyl polymer fine particles swollen with a solvent and colored with an oil-based dye are added. Examples of the polymer that can be suitably used include mainly (meth) acrylic acid ester copolymer fine particles, and it is described that a preferable condition is that the glass transition temperature is 30 ° C. or lower. In the proposal, there is no description regarding the particle size. It is obvious that fine particles swollen with a solvent at such a low glass transition temperature have film-forming properties when dried at room temperature, and when such ink is used, nozzle clogging may frequently occur. Easy to guess.
[0007]
(Pigment-dispersed ink)
In order to improve the drawbacks of water-soluble dye-type inks, proposals have been made to use carbon black or organic pigments as recording materials. In such a pigment dispersion type ink, the water resistance of the ink is greatly improved. However, these pigments have a high specific gravity of 1.5 to 2.0, and attention must be paid to the sedimentation of dispersed particles. In order to stably disperse such a high specific gravity pigment, it is necessary to finely disperse the average particle diameter to about 0.1 μm or less, resulting in a very expensive ink having a high dispersion cost. Further, when the particle diameter is 0.1 μm or less, the effect of preventing blurring is insufficient, and high-quality recorded characters / images cannot be obtained. Further, there is a problem that the ink physical properties such as surface tension and foaming property are limited by the dispersant used for dispersion.
[0008]
(Colored resin particle type ink)
Proposals for coloring water-dispersible resins with oil-soluble dyes or hydrophobic dyes have been made as inks for inkjet recording. These are proposals relating to “inks using colored polymer particles as a recording agent”. For example, JP-A-54-58504 proposes an ink in which a mixture of a hydrophobic dye solution and vinyl polymer fine particles is dispersed in an oil-in-water type. It is disclosed in the text that the vinyl polymer fine particles swell in the solvent of the dye solution by being mixed with the hydrophobic dye solution and further colored with the dye. Since a hydrophobic dye is used as a recording agent, the obtained image has water resistance. In this proposal, water is used as a continuous phase and colored vinyl polymer particles swollen with a solvent are used as a dispersed phase, so that water has a dominant ink viscosity, and the solvent has a certain degree of high viscosity (low volatility). It is allowed to use things.
[0009]
Japanese Patent Application Laid-Open Nos. 55-139471 and 3-250069 propose inks using emulsion polymerization or dispersion polymerization particles dyed with a dye. The main point of the proposal is the prevention of blurring by using colored particles as a dispersoid and water (transparent) as a medium, as in JP-A-54-58504. It is necessary to be fixed on the recording paper by forming the film. From the viewpoint of necessity of film formation and ensuring dispersion stability, it is suggested that the desirable particle size is in the submicron region.
In any proposal, the water dispersible resin is a vinyl polymer. In these vinyl polymers, it is difficult to color at a high concentration because the solubility of the dye in the resin is low. In Japanese Patent Laid-Open No. 54-58504, it is accepted that dyeing property is increased by swelling polymer fine particles with a solvent. In this case, however, there is a problem of nozzle clogging due to dry film formation at the nozzle tip. Arise.
Japanese Patent Laid-Open No. 4-185672 discloses that an ink composed of colored resin particles and an aqueous medium dissolves a water-soluble compound in the aqueous medium, thereby reducing the specific gravity difference between the colored resin particles and the aqueous medium to 0.04 or less. It has been proposed to prevent this.
Here, inorganic salts are preferably used as the water-soluble compound. However, when such inorganic salts are dissolved in an aqueous medium, the ionic strength in the system increases and the stability of the dispersion system decreases, so that the colored resin particles agglomerate and cannot maintain fluid properties as an inkjet ink.
In JP-A-4-185673 and JP-A-4-185673, the effective specific gravity is lowered by swelling the colored resin particles with a solvent in the ink comprising the colored resin particles and the aqueous medium. It has been proposed to make the difference in specific gravity of 0.04 or less. In such a case, as described above, it is difficult to avoid nozzle clogging.
[0010]
[Problems to be solved by the invention]
As described above, it is difficult to improve the recording quality of water-soluble dye-type ink with the prior art, and further, pigment-dispersed ink and colored resin particles that have been developed to solve the problems of water-soluble dye-type ink Satisfactory results have not been obtained with mold inks.
The present inventors have aimed to improve the recording quality of water-based inks for ink jet recording, and in particular, in inks using organic pigment fine dispersions as recording materials, only when specific resin fine particles are added, significant recording quality is achieved. The present inventors have found that it is possible to achieve both improvement, stability against particle sedimentation, and reliability against nozzle clogging.
[0011]
[Means for Solving the Problems]
That is, the present invention relates to an ink for inkjet recording using an aqueous fine dispersion of an organic pigment as a recording agent, and has a specific gravity of 0.9 to 1.05 and an average particle size of 0.2 to 1.0 μm. And the Vicat softening point obtained by emulsifying means without using an emulsifier is in the range of 40 to 100 ° C. An ink for inkjet recording, characterized by containing 0.5 to 15% by weight of synthetic resin fine particles, wherein the specific gravity of the synthetic resin fine particles is in the range of 0.93 to 1.00, and the average particle size is 0.00. 2. The ink for ink jet recording according to claim 1, wherein the ink has a specific gravity of 0.93 to 1.00 and an average particle size of 0.3 to 0.00. An ink for ink-jet recording characterized by being in the range of 8 μm, wherein the synthetic resin fine particles are non-swellable with respect to lower alcohol and / or alkylene glycol and / or alkanolamines And the synthetic resin fine particles are made of a (co) polymer containing ethylene and / or propylene in an amount of 50% by weight or more. Ink jet recording ink, wherein the synthetic resin fine particles are made of a (co) polymer composed of 50% by weight or more of methylstyrene, and the synthetic resin fine particles are ethylene / (meth) An ink for ink-jet recording comprising an acrylic acid copolymer, wherein the synthetic resin fine particles are made of an ethylene / (meth) acrylic acid copolymer. With fat Ink for ink-jet recording, characterized in that The Furthermore, the organic pigment has a dispersed particle diameter of 0.1 μm or less.
[0012]
The organic pigment used in the present invention can be selected from known organic pigments as necessary. More preferably, those having a hue angle H in the range of CIEELCH chromaticity coordinates (CIELAB 1976 chromaticity coordinates cylindrical coordinate system display) in the range of 85 to 120 degrees, preferably 90 to 110 degrees, yellow dye, 230 to 270 degrees, preferably It is preferable to use a dye at 250 to 265 degrees as a cyan dye and a magenta dye at 330 to 360 degrees. As an organic pigment, C.I. I. Classified as pigment color, C.I. I. Those that are classified as bat color can be mainly used. In addition to these, a part of a dye insoluble in water can also be used as a pigment. As such dyes, some oil-based dyes that are hydrophobic and not soluble in lower alcohols and glycols, which are hydrophilic solvents, can be used.
[0013]
More specifically
C. I. Pigment Yellow 3, 13, 14, 15, 16, 17, 185,
C. I. Pigment Red 81, 95, 122, 184
C. I. Pigment Violet 23
C. I. Pigment Blue 15, 16
Etc. can be used suitably.
As a water dispersion method, a sand mill, a ball mill, an attritor, a paint shaker, or the like can be used. As a dispersant necessary for water dispersion, a known anionic, nonionic, or cationic dispersant can be used as necessary. However, in the present invention, the amount of such a dispersant should be minimized, and it is preferable to use an organic pigment that has been subjected to a surface treatment or a graft treatment, and that is dispersed in water without using a dispersant. The organic pigment is blended in the ink in an amount of 0.3 to 15 wt%, preferably 0.5 to 10 wt%, more preferably about 2.0 to 8.0 wt%. The dispersed particle diameter of the organic pigment is preferably 0.1 μm or less, more preferably 0.08 μm or less, and further preferably 0.05 μm or less. If the dispersed particle size is large, the organic pigment particles may be settled.
In the present invention, a small amount of water-soluble dye may be added for adjusting the hue and the like. The water-soluble dye can be appropriately selected from known dyes. As water-soluble dyes, acidic dyes, direct dyes, anionic dyes such as some food dyes, and cationic dyes such as basic dyes are preferably used. The addition of water-soluble dyes must be kept to a minimum because it causes a decrease in water resistance.
[0014]
Usually, a water-soluble organic compound is added to the ink for ink jet recording for the purpose of adjusting the surface tension, viscosity, moisture retention, penetrating speed of the recording paper, and the present invention is no exception. Water-soluble organic compounds include methanol, ethyl alcohol, propanol, isopropanol, butanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, thiodiglycol, propylene glycol, dipropylene glycol, polypropylene glycol, neopentyl glycol, Compounds such as glycerin, monoethanolamine, diethanolamine, nitrile triethanol, ethylenediamine ethyl cellosolve, butyl cellosolve, tertiary butyl cellosolve, and alkylene glycol monoether can be used alone or in appropriate combination of a plurality of components. In particular, alkylene glycols are preferably added to the ink in an amount of about 2 to 10 wt%, preferably about 3 to 7 wt%.
[0015]
A feature of the present invention is that the organic pigment water-based finely dispersed ink contains 0.5 to 15% by weight of synthetic resin fine particles having a specific gravity of 0.9 to 1.05 and an average particle size of 0.2 to 1.0 μm. is there.
The specific gravity of the synthetic resin fine particles is preferably in the range of 0.93 to 1.00, more preferably in the range of 0.94 to 0.98. The average particle diameter is preferably in the range of 0.3 to 0.8 μm, more preferably in the range of 0.35 to 0.7 μm, and still more preferably in the range of 0.4 to 0.6 μm. If the specific gravity is below this range, there is a possibility of phase separation due to particle floating when the ink is stored for a long time. If the specific gravity greatly exceeds this range, sedimentation may occur. When the average particle diameter is below this range, the recording quality is not improved sufficiently, and blurring is likely to occur particularly on paper of poor quality such as recycled paper. When the average particle diameter exceeds this range, the risk of phase separation due to sedimentation or floating increases, and the risk of nozzle clogging increases. It is further interesting that when the particles having a particle size exceeding this range are added, the blurring preventing effect gradually decreases. This is considered to be due to the fact that the particle diameter is too large, and the effect of the particles blocking the fiber gaps of the recording paper is reduced. In the present invention, the lower limit of the particle size distribution is not limited as long as problems such as an increase in ink viscosity do not occur, and a range of approximately 0.01 μm is allowed. However, the upper limit of the particle size distribution needs to be controlled to about 2.0 μm, preferably 1.5 μm, more preferably 1.2 μm or less. That is, the preferable particle size distribution in the present invention is not necessarily a normal distribution, and a shape with a slight tail on the small particle side is preferable. Highly monodispersed particles are not necessarily preferred.
[0016]
Furthermore, such synthetic resin fine particles are required to be non-swellable with respect to lower alcohol and / or alkylene glycol and / or alkanolamines which are water-soluble organic compounds which are ink additives. The term “non-swelling” as used herein means that the resin does not dissolve in the organic compound as a physical property of the resin, and of course does not absorb 10 wt%, preferably 5 wt% or more of the organic compound. From another point of view, it is meant that such an aqueous dispersion of resin particles does not cause a decrease in film forming temperature of 10 ° C. or higher, preferably 5 ° C. or higher. When these water-soluble organic compounds added auxiliary to the ink swell, dry film formation of resin particles occurs at the tip of the nozzle, causing nozzle clogging.
[0017]
In the resin fine particles used in the present invention, the minimum film forming temperature is preferably 40 ° C. or higher, more preferably 60 ° C. or higher, still more preferably in the range of 70 to 100 ° C., and further It is preferable that it is the range of 80-100 degreeC. In order to realize such minimum film-forming temperature, the Vicat softening point defined by ASTM D1525-70 is 40-100. ℃ That it is Is necessary Furthermore, it is preferable that it is 45-80 degreeC, and it is still more preferable that it is 50-70 degreeC.
[0018]
The resin fine particles having such properties include (co) polymers containing 50% by weight or more of ethylene and / or propylene, (co) polymers comprising 50% by weight or more of methylstyrene, and ethylene / (meth) acrylic acid copolymers. The resin fine particles can be exemplified. As methylstyrene, any of isomers of α, ortho, meta and para positions may be used, but those having a methyl group at the meta position and para position are particularly preferred. Such resin fine particles can be obtained by any method such as a so-called emulsion polymerization method. Is When using resin fine particles obtained by emulsion polymerization, use those obtained by techniques that do not use emulsifiers such as soap-free emulsion polymerization. The This is because emulsifiers and the like often have undesirable effects on various performances as inks for inkjet recording. The resin particles particularly preferably used in the present invention are so-called ethylene / (meth) acrylic acid copolymer as a main component and partially ion-crosslinked by alkali metal ions, alkaline earth metal ions, ammonium ions or the like. It is preferable to use an aqueous dispersion made of an ionomer resin. Such an aqueous dispersion of resin can be obtained by a method other than emulsion polymerization such as forced mechanical emulsification using both heating and mechanical stirring, and the degree of freedom in the method of obtaining a fine dispersion of resin particles without using an emulsifier. Is expensive. Examples of the aqueous dispersion of the resin include trade names such as Chemipearl S-100, S-200, S-300, and SA-100 type [Mitsui Petrochemical Co., Ltd.].
[0019]
A fluorine-based or silicone-based antifoaming agent can be added to the ink of the present invention. Furthermore, various bactericides and fungicides, and if necessary, inorganic and organic pigments can be added to the extent that transparency is not impaired.
Further, addition of a trace amount of alkali metal ions or alkaline earth metal ions of about 5 to 50 ppm may be preferable in order to reduce the viscosity of the aqueous dispersion.
The pH of the ink of the present invention is preferably 4 or more, more preferably 6 or more, still more preferably 7.5 or more, and even more preferably in the range of 7.5 to 9.5.
The viscosity of the ink of the present invention is preferably in the range of 1.5 to 30 centipoise, more preferably 1.8 to 15 centipoise, still more preferably 2.0 to 10 centipoise, and 3.0 to 6.0 centipoise. A range is even more preferred.
The ink for inkjet recording of the present invention is preferably combined with an ink discharge means that does not use thermal energy as a driving force. Further, the ink for ink jet recording of the present invention is preferably combined with a means for fixing the ink by heating the recording paper to 40 ° C.
[0020]
Since the specific gravity of the organic pigment is as high as about 1.8 to 2.5, if it is not finely dispersed to about 0.1 μm or less, it may cause sedimentation when left standing for a long period of time and may cause unevenness of the ink solid content. . Since the particle diameter is sufficiently smaller than the fiber gap on the surface of general recording paper, the microscopic flow behavior of the organic pigment particles on the recording paper is close to that of a water-soluble dye. Therefore, the degree of “brightening” in relation to the recording quality and the printing quality is not much different from that of the water-soluble dye type ink, and a slight improvement is observed.
It is well known that recording quality is improved when resin fine particles are added to water-soluble dye-type ink, and many patent proposals have been made. The same can be said for inks in which organic pigments are finely dispersed. Therefore, the means of adding resin fine particles to improve the recording quality of the organic pigment water dispersion type ink can be easily analogized.
However, attempts to improve the recording quality by adding these resin fine particles that have been proposed so far to the ink only have a problem of the recording quality, and the storage stability of the ink itself and the reliability against clogging of the inkjet nozzles are considered. There is nothing to consider. An object of the present invention is to provide an ink that achieves high recording quality while satisfying storage stability and reliability against clogging, and only a specific one among many resin fine particles has this purpose. It was made as a result of finding satisfaction.
[0021]
In the present invention, the specific gravity of the resin and the dispersed particle diameter are simultaneously defined. However, the storage stability and the recording quality are compatible only when these are compatible. Further, by satisfying this condition and having a specific softening temperature and the property that the physical properties are not greatly influenced by other ink additive components, reliability against nozzle clogging is ensured.
Furthermore, what should be noted in the present invention is that the recording density is improved by adding such resin fine particles to the ink. This fact means that the organic pigment fine particle component that penetrates and diffuses along with the medium (water) along the fibers of the recording paper is blocked by the added resin fine particles, thereby suppressing blurring and the vicinity of the surface of the recording paper. It can be understood that this is because a relatively large amount remains. Since this effect is particularly observed particularly in the resin fine particles satisfying the limiting conditions of the present invention, it is possible to evaluate the level of the effect of preventing blurring.
[0022]
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples shown here. .
[Example 1]
Organic pigment water dispersion “Levanyl Blue GZ” (BAYER, average particle size 0.06 μm, CI Pigment Blue 15 finely dispersed using nonionic dispersant), deionized water, a predetermined amount of ethylene Glycol, isopropyl alcohol, and nitrile triethanol were added and mixed. Further, a separately prepared aqueous dispersion of resin fine particles was gently dropped with stirring and mixed well, and then filtered through a 1.0 μm membrane filter to prepare an ink jet recording ink having the following composition.
[0023]
Prototype ink (1)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Ethylene-propylene copolymer fine particles (non-volatile equivalent) 5.0 wt%
Water remaining
Here, the ethylene-propylene copolymer fine particle is a copolymer resin particle aqueous dispersion obtained by soap-free emulsion polymerization comprising 90 wt% ethylene and 10 wt% propylene.
Average particle size 0.38μm
Resin specific gravity 0.92
Minimum filming temperature 95 ° C
Vicat softening point 76 ℃
It is. The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol is added to 100 wt parts of an aqueous dispersion prepared with a non-volatile content concentration of 20 wt%, the minimum film formation does not change and the particle diameter does not change, so the swelling property by lower alcohol is a fact. It was judged not to be above.
[0024]
The ink viscosity was adjusted to 3.2 centipoise and the surface tension was adjusted to 54 dyn / cm. In the examples and comparative examples shown below, the ink viscosity is in the range of 2.8 to 3.5 centipoise and the surface tension is in the range of 50 to 57 dyn / cm from the viewpoint of comparison under certain conditions. It was adjusted to.
The average particle size was measured by a light scattering particle size distribution meter, the resin specific gravity was measured by a floatation method, the minimum film-forming temperature was measured by a conventional method, and the Vicat softening point was measured by a method according to ASTM D1525-70.
The obtained prototype ink (1) was charged into an inkjet printer IO735X (manufactured by Sharp), printed on recycled paper, and the recording quality was visually evaluated. In addition, a parallel line pattern having a 1-dot width and a 1-dot width line is printed on a calligraphic half paper, and the line thickness is calculated from the original line width calculated from the dot pitch and the actual printed line width. The width was set to be bleed. At the same time, the optical density of the solid printing part (Macbeth optical density meter) was measured. The obtained recorded matter was immersed in ion-exchanged water, and the water resistance was evaluated by bleeding the coloring material. The ink jet printer in which ink was charged was left in a high-temperature dry atmosphere of 40 ° C. and 30% RH for one week, after which the printer was restarted and nozzle clogging was evaluated based on the number of head cleanings required until head recovery. . Further, fill the test ink with a depth of 10 cm into a test tube, seal it, and leave it for 3 months. After 3 months, the presence of sediment at the bottom of the test tube, ink sampled from 5 mm below the liquid level, and 1 cm from the bottom The storage stability was evaluated based on the solid content concentration ratio with the ink sampled from the upper part. The solid content concentration represents the initial concentration as 100, and is a value converted into a resin particle component in the ink non-volatile content (assuming that no sedimentation / concentration gradient of the recording material occurs). The results are shown in Table 1. Table 2. Shown in
[0025]
[Table 1]

[0026]
[Table 2]

Table 1. Table 2. During,

It is.
[0027]
[Example 2]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (2)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Paramethylstyrene-butyl methacrylate copolymer fine particles (non-volatile equivalent) 5.0 wt%
Water remaining
Here, paramethylstyrene-butyl methacrylate copolymer fine particles are copolymer resin particle aqueous dispersions obtained by soap-free emulsion polymerization comprising 75% by weight of paramethylstyrene, 20% by weight of butyl methacrylate and 5% by weight of divinylbenzene. ,
Average particle size 0.45μm
Resin specific gravity 1.02
Minimum filming temperature 102 ° C
Vicat softening point 95 ℃
It is.
This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but some swelling was observed in methanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of an aqueous dispersion prepared with a nonvolatile content concentration of 20 wt%, the minimum film formation decreased by about 4 ° C., but the particle size did not change appreciably, so lower alcohol It was judged that the swelling property was low.
[0028]
[Example 3]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (3)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Ionomer resin fine particles S-200 (non-volatile content conversion) 5.0wt%
Water remaining
Here, the ionomer resin fine particles are composed of an ethylene-methacrylic acid copolymer (80-90 wt% ethylene, 10-20 wt% methacrylic acid) partially ion-crosslinked with an alkali metal ion, and an aqueous dispersion obtained by a soap-free emulsification technique. It is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl S-200,
Average particle size 0.43μm
Resin specific gravity 0.95
Minimum film forming temperature 85 ℃
Vicat softening point 57 ℃
It is.
[0029]
The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol is added to 100 wt parts of an aqueous dispersion prepared with a non-volatile content concentration of 20 wt%, the minimum film formation does not change and the particle diameter does not change, so the swelling property by lower alcohol is a fact. It was judged not to be above.
[0030]
[Example 4]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (4)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Ionomer resin fine particles S-300 (non-volatile content conversion) 2.0wt%
Water remaining
Here, the ionomer resin fine particles are composed of an ethylene-methacrylic acid copolymer (80-90 wt% ethylene, 10-20 wt% methacrylic acid) partially ion-crosslinked with an alkali metal ion, and an aqueous dispersion obtained by a soap-free emulsification technique. It is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl S-300,
Average particle size 0.53μm
Resin specific gravity 0.95
Minimum filming temperature 94 ℃
Vicat softening point 67 ℃
It is. Similar to the ionomer resin used in Example 3, this resin was judged to be virtually free from swelling by lower alcohols.
[0031]
[Example 5]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (5)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Modified ionomer resin fine particles SA-100 (non-volatile equivalent) 2.0 wt%
Water remaining
The modified ionomer resin fine particles are composed of a graft copolymer obtained by grafting styrene to an ethylene-methacrylic acid copolymer (ethylene 80 to 90 wt%, methacrylic acid 10 to 20 wt%) partially ion-crosslinked with an alkali metal ion. It is an aqueous dispersion obtained by a soap-free emulsification technique, and is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl SA-100.
Average particle size 0.75μm
Resin specific gravity 1.00
Minimum filming temperature 70 ° C
Vicat softening point 55 ℃
It is. This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but some swelling was observed in methanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of an aqueous dispersion prepared with a non-volatile concentration of 20 wt%, the minimum film formation decreased by about 2 ° C., but there was no detectable change in the particle size, so lower alcohol It was judged that the swelling property was low.
[0032]
[Comparative Example 1]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (6)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Water remaining
This prototype ink is a so-called typical organic pigment finely dispersed ink that does not contain resin particles.
[0033]
[Comparative Example 2]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (7)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Vinylidene chloride copolymer latex (nonvolatile content) 5.0wt%
Water remaining
Here, the vinylidene chloride copolymer latex is an emulsified dispersion latex using an aliphatic soap of vinylidene chloride-vinyl chloride copolymer.
Average particle size 0.15μm
Resin specific gravity 1.36
Minimum filming temperature 135 ° C
Vicat softening point 125 ℃
It is. As a result of the same evaluation as in Example 1, this resin was judged to have low swellability due to lower alcohol.
[0034]
[Comparative Example 3]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (8)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Vinylidene chloride copolymer latex (nonvolatile content) 5.0wt%
Water remaining
The vinylidene chloride copolymer latex is an emulsion-dispersed latex using an aliphatic soap of vinylidene chloride-vinyl chloride copolymer as in Comparative Example 1.
Average particle size 0.45μm
Resin specific gravity 1.36
Minimum filming temperature 135 ° C
Vicat softening point 125 ℃
The particle diameter is larger than that of Comparative Example 1. As a result of the same evaluation as in Example 1, this resin was judged to have low swellability due to lower alcohol.
[0035]
[Comparative Example 4]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (9)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Styrene-butadiene copolymer latex (non-volatile content) 5.0wt%
Water remaining
Here, the styrene-butadiene copolymer latex is an emulsion-dispersed latex using a copolymer aliphatic soap containing 25 wt% of styrene.
Average particle size 1.10 μm
Resin specific gravity 0.97
Minimum filming temperature 24 ° C
Vicat softening point 10 ℃
It is. This resin was dissolved in methanol, ethanol and isopropanol. It did not dissolve in ethylene glycol and nitrile triethanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of an aqueous dispersion prepared with a non-volatile content concentration of 20 wt%, the minimum film formation decreased by 24 ° C. or more, that is, when it did not fall below the freezing point, the film was formed by natural drying. Therefore, the swelling property was judged to be very high.
[0036]
[Comparative Example 5]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (10)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Polymethylmethacrylate latex (nonvolatile content) 5.0wt%
Water remaining
Here, polymethyl methacrylate latex is latex particles having high monodispersibility obtained by soap-free emulsion polymerization.
Average particle size 0.52μm
Resin specific gravity 1.19
Minimum filming temperature 120 ° C
Vicat softening point 110 ℃
It is. This resin did not dissolve in methanol, ethanol, isopropanol, ethylene glycol, and nitrile triethanol, but the surface showed some softening and swelling signs in methanol and isopropanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of an aqueous dispersion prepared with a nonvolatile content concentration of 20 wt%, the minimum film formation decreased by 12 ° C. Swellability was not so high, but some were recognized.
[0037]
[Comparative Example 6]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (11)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Acrylic copolymer latex (non-volatile equivalent) 5.0wt%
Water remaining
Here, the acrylic copolymer latex is copolymer latex particles obtained by emulsion polymerization comprising methyl methacrylate, ethyl methacrylate, and butyl methacrylate.
Average particle size 0.45μm
Resin specific gravity 1.08
Minimum filming temperature 84 ℃
Vicat softening point 80 ℃
It is. The resin did not dissolve in ethanol, ethylene glycol, and nitrile triethanol, but some solubility was observed in methanol and isopropanol. When 10 wt parts of isopropyl alcohol was added to 100 wt parts of an aqueous dispersion prepared with a non-volatile content concentration of 20 wt%, the minimum film formation was reduced by nearly 30 ° C., and the swellability was judged to be high.
[0038]
[Comparative Example 7]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. However, the filtration step using a 1.0 μm membrane filter was omitted. The results are shown in Table 1. Table 2. Shown in
Prototype ink (12)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Polyolefin fine particle W-500 (non-volatile content conversion) 5.0wt%
Water remaining
Here, the polyolefin fine particle is an aqueous dispersion made of a low molecular weight polyolefin (mainly polyethylene) and obtained by a soap-free emulsification technique, and is marketed by Mitsui Petrochemical Co., Ltd. as Chemipearl W-500.
Average particle size 2.50 μm
Resin specific gravity 0.92
Minimum filming temperature 90 ° C
Vicat softening point 38 ℃
It is. The resin did not dissolve in methanol, ethanol, isopropyl alcohol, ethylene glycol, and nitrile triethanol, and no swelling was observed. Furthermore, even when 10 wt parts of isopropyl alcohol is added to 100 wt parts of an aqueous dispersion prepared with a non-volatile content concentration of 20 wt%, the minimum film formation does not change and the particle diameter does not change, so the swelling property by lower alcohol is a fact. It was judged not to be above.
[0039]
[Comparative Example 8]
An ink for inkjet recording having the following composition was prepared in the same procedure as in Example 1, and the same evaluation was performed. The results are shown in Table 1. Table 2. Shown in
Prototype ink (13)
Water-soluble dye C.I. Direct Blue 86 purified product 1.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Water remaining
This prototype ink is a so-called typical water-soluble dye-type ink that does not contain resin particles.
[0040]
[Example 6]
The organic pigment aqueous dispersion was replaced with “Levantyl Yellow 10GZ” (BAYER, CI Pigment Yellow 3 finely dispersed using a nonionic dispersant having an average particle size of 0.06 μm), and the following Example 1 Prototype inks were prepared according to the same procedure as above and evaluated in the same manner. The results are shown in Table 1. Table 2. Shown in
Prototype ink (14)
Organic pigment (pigment equivalent) 10.0wt%
Ethylene glycol 5.0wt%
Isopropyl alcohol 0.8wt%
Nitrile triethanol 0.2wt%
Ionomer resin fine particles S-200 (non-volatile content conversion) 5.0wt%
Water remaining
Here, the ionomer resin fine particles are the same as those used in Example 3.
[0041]
[Example 7]
The organic pigment aqueous dispersion was replaced with “Levanyl Carmin GZ” (BAYER, average particle size 0.06 μm, CI Pigment Red 95 finely dispersed using a nonionic dispersant). A prototype ink (15) was obtained with the same composition and procedure as in Example 6. Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0042]
[Example 8]
The organic pigment aqueous dispersion was replaced with “Levanyl Violet BNZ” (BAYER's average particle size 0.06 μm, CI Pigment Violet 23 finely dispersed using a nonionic dispersant). A prototype ink (16) was obtained with the same composition and procedure as in Example 6. Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0043]
[Example 9]
20 parts by weight of “CI Pigment Red 122”, 10 parts by weight of a partially esterified product of styrene-maleic acid copolymer resin (acid value 2000 eq / ton) (nonvolatile content 20 wt%), 70 parts by weight of ion-exchanged water The attritor was charged and dispersed for about 3 hours. The obtained dispersion was filtered with 5B filter paper and then filtered with a membrane filter of 1.0 μm, a membrane filter of 0.4 μm, and a membrane filter of 0.2 μm, and finally an aqueous pigment dispersion having an average particle size of 0.08 μm was obtained. It was. A prototype ink (17) was obtained using the aqueous pigment dispersion thus obtained, except that the composition and procedure were the same as in Example 6. Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0044]
[Example 10]
A prototype ink (18) was obtained by the same composition and procedure as in Example 9, except that the organic pigment was changed to “Permanent Rubin F6B (CI Pigment Red 184)” (manufactured by HOECHST). Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0045]
Example 11
A prototype ink (19) was obtained by the same composition and procedure as in Example 9 except that the organic pigment was changed to “Permanent Pink F3B” (manufactured by HOECHST). Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0046]
Example 12
A prototype ink (20) was obtained by the same composition and procedure as in Example 9, except that the organic pigment was changed to “Paliotool Yellow S1155 (CI Pigment Yellow 185” (manufactured by BASF)). The same evaluation is performed, and the results are shown in Table 1 and Table 2.
[0047]
Example 13
A prototype ink (21) was obtained by the same composition and procedure as in Example 9 except that the organic pigment was changed to “CI Pigment Yellow 17”. Thereafter, the same evaluation as in Example 1 was performed, and the results are shown in Table 1. Table 2. Shown in
[0048]
【The invention's effect】
As described above, the inkjet recording ink of the present invention is capable of high-quality recorded images and printing, has high resistance to nozzle clogging, and has excellent characteristics that are stable even when stored for a long period of time. It is a thing which has.

Claims (8)

Ink jet recording ink using an aqueous fine dispersion of an organic pigment as a recording agent is obtained by emulsification means having a specific gravity of 0.9 to 1.05 and an average particle size of 0.2 to 1.0 μm and not using an emulsifier. An ink for inkjet recording, comprising 0.5 to 15% by weight of synthetic resin fine particles having a Vicat softening point in the range of 40 to 100 ° C.   The ink for inkjet recording according to claim 1, wherein the specific gravity of the synthetic resin fine particles is in the range of 0.93 to 1.00, and the average particle diameter is in the range of 0.3 to 0.8 µm.   2. The ink for ink jet recording according to claim 1, wherein the synthetic resin fine particles are non-swellable with respect to lower alcohol and / or alkylene glycol and / or alkanolamines.   2. The ink for ink jet recording according to claim 1, wherein the synthetic resin fine particles are a (co) polymer containing 50% by weight or more of ethylene and / or propylene.   2. The ink for ink jet recording according to claim 1, wherein the synthetic resin fine particles are a (co) polymer comprising 50% by weight or more of methylstyrene.   The ink for inkjet recording according to claim 1, wherein the synthetic resin fine particles are an ethylene / (meth) acrylic acid copolymer. The synthetic resin particles ethylene / (meth) inkjet recording ink according to claim 1, wherein the ionomer resins consisting of acrylic acid copolymer. The ink for inkjet recording according to claim 1, wherein the dispersed particle diameter of the organic pigment is 0.1 μm or less.