JP2014205768A - Aqueous ink for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for inkjet excellent in printability to a general printing base material, especially a base material having low water absorption such as a coat paper, an art paper or a vinyl chloride sheet, capable of providing a high quality image, and excellent in discharge stability.SOLUTION: There is an ink for aqueous inkjet containing at least an organic solvent, a surfactant and water, at least (A) a water soluble organic solvent having the boiling point of 100 to 180°C and (B) an organic solvent having the boiling point of 200 to 280°C and surface tension of 20 to 30 mN/m or less are contained as the organic solvent, and the surfactant is a polysiloxane-based surfactant at 0.5 to 3 wt.%.

Description

  The present invention is excellent in printability to a general printing substrate, particularly a substrate having low water absorption such as coated paper, art paper, and a vinyl chloride sheet, and is capable of obtaining a high quality image and discharging. The present invention relates to an inkjet ink composition having excellent stability.

  The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. According to this method, there is an advantage that not only the noise of the apparatus to be used is small and the operability is good, but also colorization is easy and plain paper can be used as a recording member. It is widely used as an output machine in offices and homes.

  On the other hand, in industrial applications, it is expected to be used as an output machine for digital printing due to improvements in inkjet technology, and even for non-absorbable substrates (plastic substrates such as PVC and PET) using solvent inks and UV inks. Printing machines capable of printing have actually been marketed. However, in recent years, the demand for water-based inks has increased from the standpoint of environmental friendliness.

  As ink-jet water-based inks, as described in Patent Documents 1, 2, and 3, the development of inks for which special printing paper such as plain paper or photographic glossy paper has been developed for a long time. On the other hand, in recent years, the application of the ink jet recording method is expected to be expanded, and the need for direct printing on a non-absorbent base material used for coated paper such as coated paper or outdoor advertising is increasing. Since conventional ink performs drawing by absorbing liquid droplets on paper, if the ink is printed on a substrate having low water absorption, the image is blurred and cannot be used.

Patent Document 4 presents an ink capable of performing direct printing on coated paper without bleeding by using crystalline sugar alcohol. In this method, sugar alcohol is crystallized after printing, thereby reducing the fluidity of the ink and suppressing bleeding of the image. However, since sugar alcohol remains in the coating film in this method, there is a concern that the coating film deteriorates due to dissolution of the sugar alcohol by alcohol or the like.

Japanese Patent No.4764562 Japanese Patent No. 4595281 JP 2008-247941 A JP 2011-178980

  The object of the present invention is excellent in printability on a general printing substrate, particularly a substrate having low water absorption, such as coated paper, art paper or vinyl chloride sheet, and is capable of obtaining a high quality image, and In addition, the present invention provides an inkjet ink composition having excellent ejection stability.

  That is, the present invention comprises at least an organic solvent, a surfactant, and water, and as the organic solvent, at least (A) a water-soluble organic solvent having a boiling point of 100 ° C. or more and 180 ° C. or less and (B) a boiling point of 200 ° C. or more. And an organic solvent having a surface tension of 20 mN / m or more and 30 mN / m or less, wherein the surfactant is a polysiloxane surfactant.

Further, the present invention relates to the water-based inkjet ink, wherein the surfactant is selected from the general formula 1 or 2.
3. The water-based inkjet ink according to claim 2, further comprising a compound of the general formula 3 as the surfactant.

The present invention also relates to the water-based inkjet ink described above, wherein the surfactant is contained in the ink in an amount of 0.5% to 3% by weight.
The water-soluble organic solvent (A) having a boiling point of 100 ° C. or more and 180 ° C. or less includes any one selected from propylene glycol monomethyl ether, methoxybutanol, and 3-methyl-3-methoxybutanol. The present invention relates to the water-based inkjet ink.

Further, the present invention relates to a printing method for performing printing by attaching ink droplets to a printing medium while heating the printing medium to 40 to 80 ° C., and relates to an inkjet printing method using the above-described aqueous inkjet ink .
In addition, the present invention relates to the above inkjet printing method, wherein the printing medium is a non-water-absorbing substrate or a hardly water-absorbing substrate.

  According to the present invention, it is possible to obtain a high-quality image with excellent printability on a general printing base material, particularly a base material having low water absorption such as coated paper, art paper, and vinyl chloride sheet. It has become possible to provide an ink-jet ink composition having excellent stability.

  Hereinafter, the present invention will be described with reference to preferred embodiments.

  In the present invention, a water-soluble organic solvent (solvent A) having a boiling point of 100 ° C. or higher and 180 ° C. or lower as a polysiloxane surfactant and an organic solvent and a boiling point of 200 ° C. or higher and 280 ° C. or lower and a surface tension of 20 mN / m or higher and 30 mN By combining an organic solvent (solvent B) that is less than or equal to / m, the ejection stability during printing, the drying speed, and the print quality are improved.

  The principle is considered as follows. During ink jet printing, ink droplets wet and spread on the print medium while the water evaporates. Printing defects such as missing or beading occur. In order to solve this problem, it is important to increase the speed of wetting and spreading with respect to the printing medium of the ink and to sufficiently spread the ink before pigment aggregation occurs. The present inventors have confirmed that the rate of wetting and spreading is improved by combining a solvent having a high boiling point and a low surface tension (solvent B) and a polysiloxane surfactant. In addition, combined use of a low boiling point solvent (solvent A) speeds up the drying of the ink, eliminates printing bleeding, and enables high-quality printed matter to be printed at high speed.

  The main components of the present invention are described below.

  The polysiloxane surfactant is not particularly limited as long as it is generally used for ink, paint, etc., but it is high by using a surfactant having a structure represented by general formula 1 or general formula 2. Discharge stability and print quality can be obtained. Further, when a surfactant having a structure represented by the general formula 3 is used in combination, higher discharge stability can be obtained.

  The blending amount of the surfactant in the ink is preferably 0.5 to 3% by weight. More preferably, it is 0.8-2 weight%, More preferably, it is 1-1.5 weight%.

  Hereinafter, the polysiloxane surfactants represented by the general formulas 1 to 3 will be described.

式中aは1〜500の整数、bは0〜10の整数。R1はアルキル基、またはアリール基を示す。R2は下記(A), (B), (C), (D)の内の何れかの置換基で示され、R2の内、少なくとも一つは(A)を含む。 [General formula 1]

In the formula, a is an integer of 1 to 500, and b is an integer of 0 to 0. R1 represents an alkyl group or an aryl group. R2 is represented by any one of the following substituents (A), (B), (C), and (D), and at least one of R2 includes (A).

cは1〜20の整数であり、dは0〜50の整数であり、eは0〜50の整数である。R3は水素原子またはアルキル基を示し、R4は水素原子、アルキル基、アシル基の何れかを示す。 (A)

c is an integer of 1 to 20, d is an integer of 0 to 50, and e is an integer of 0 to 50. R3 represents a hydrogen atom or an alkyl group, and R4 represents any one of a hydrogen atom, an alkyl group, and an acyl group.

fは2〜20の整数である。R5は水素原子、アルキル基、アシル基、ジメチルプロピル骨格を有するエーテル基の何れかをす。 (B)

f is an integer of 2 to 20. R5 represents any one of a hydrogen atom, an alkyl group, an acyl group, and an ether group having a dimethylpropyl skeleton.

gは2〜6の整数であり、hは0〜20の整数であり、iは1〜50の整数であり、jは0〜10の整数であり、kは0〜10の整数である。R6は水素原子、アルキル基、アシル基の何れかを示す。 (C)

g is an integer of 2-6, h is an integer of 0-20, i is an integer of 1-50, j is an integer of 0-10, and k is an integer of 0-10. R6 represents any one of a hydrogen atom, an alkyl group, and an acyl group.

 (D) An alkyl group or an aryl group.

Commercial products of the compound represented by the general formula 1 include Tegotwin 4000 and Tegotwin 4100 manufactured by Evonik Degussa.

式中lは10〜80の整数を示す。R7は下記(E)の置換基で示される。 [General formula 2]

In the formula, l represents an integer of 10 to 80. R7 is represented by the following substituent (E).

mは1〜6の整数、nは0〜50の整数、oは0〜50の整数であり、n+oは1以上の整数で示される。R8は水素原子または炭素数1〜6のアルキル基、または(メタ)アクリル基である。 (E)

m is an integer of 1 to 6, n is an integer of 0 to 50, o is an integer of 0 to 50, and n + o is represented by an integer of 1 or more. R8 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a (meth) acryl group.

Examples of commercially available compounds represented by general formula 2 include BY16-201, SF8427 manufactured by Toray Dow Corning, BYK-331, BYK-333, BYK-UV3500 manufactured by BYK Chemie, and Evonik Degussa Tegoglide410, Tegoglide432, Tegoglide435, Tegoglide440, Tegoglide450 etc. are mentioned.

（pおよびqは1以上の整数であり、p+qは3〜50の整数で示される。R9は下記（Ｆ）の置換基で示され、Ｒ１０は炭素数1〜6のアルキル基で示される。）

（ｒは１〜６の整数、ｓは０〜５０の整数、ｔは０〜５０の整数であり、ｓ＋ｔは１以上の整数で示される。Ｒ１１は水素原子または炭素数１〜６のアルキル基、または（メタ）アクリル基である） [General formula 3]

(P and q are integers of 1 or more, p + q is represented by an integer of 3 to 50, R9 is represented by the following substituent (F), and R10 is represented by an alkyl group having 1 to 6 carbon atoms. )

(R is an integer of 1 to 6, s is an integer of 0 to 50, t is an integer of 0 to 50, and s + t is an integer of 1 or more. R11 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Or (meth) acrylic group)

  Examples of commercially available compounds represented by general formula 3 include SF8428, FZ-2162, 8032ADDITIVE, SH3749, FZ-77, L-7001, L-7002, FZ-2104, FZ manufactured by Toray Dow Corning. -2110, F-2123, SH8400, SH3773M, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-Chemie, Tegowet250, Tegowet260, Tegowet270, Tegowet280, Shin-Etsu Chemical, manufactured by Evonik Degussa Examples thereof include KF-351A, KF-352A, KF-353, KF-354L, KF355A, KF-615A, KF-640, KF-642, and KF-643 manufactured by Kogyo.

  In the present invention, the solvent A is a water-soluble organic solvent having a boiling point of 100 ° C. or higher and 180 ° C. or lower as an organic solvent, and a boiling point of 200 ° C. or higher and 280 ° C. or lower and a surface tension of 20 mN / m or higher and 30 mN / m or lower. Solvent B, which is an organic solvent, is included as an essential component. The addition amount of the solvent A and the solvent B in the ink is preferably 10 to 45% by weight as the total amount of the solvent A and the solvent B. When the addition amount is too small, the drying property and the wettability to the printing medium are poor, and the printing quality may be lowered depending on the printing medium. On the other hand, if it exceeds 45% by weight, the storage stability of the ink may be lowered. The amount of the solvent added is more preferably 15 to 30% by weight, further preferably 18 to 28% by weight, and most preferably 20 to 26% by weight. Further, the addition amount of each of the solvent A and the solvent B is preferably 5 to 25% by weight. More preferably, it is 8-20 weight%, More preferably, it is 10-15 weight%.

  The content weight ratio of the solvent A and the solvent B is preferably solvent A: solvent B = 1: 5 to 5: 1, more preferably solvent A: solvent B = 1: 4 to 4: 1, more preferably solvent. A: Solvent B = 1: 3 to 2: 1, most preferably Solvent A: Solvent B = 1: 2 to 2: 1.

  As the solvent A, any water-soluble organic solvent having a boiling point of 100 ° C. or higher and 180 ° C. or lower can be used. For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl Ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, methoxybutanol, 3-methyl-3-methoxybutanol, diethylene glycol methyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl ether acetate, Examples include ethyl lactate. Among these, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, methoxybutanol, and 3-methyl-3-methoxybutanol are preferable from the viewpoints of drying properties and print quality. More preferred are propylene glycol monomethyl ether, methoxybutanol and 3-methyl-3-methoxybutanol, still more preferred are propylene glycol monomethyl ether and methoxybutanol, and most preferred is propylene glycol monomethyl ether.

  As the solvent B, any organic solvent having a boiling point of 200 ° C. or higher and 280 ° C. or lower and a surface tension of 20 mN / m or higher and 30 mN / m or lower can be used. For example, 1,2-pentanediol 1,2-hexanediol, 1,2-octanediol, ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol-2-ethylhexyl ether, triethylene glycol monobutyl ether , Dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, diethylene glycol methyl butyl ether, Examples include ethylene glycol methyl butyl ether and tripropylene glycol dimethyl ether. Of these, alkanediol solvents and glycol ether solvents having 3 or more carbon atoms in the terminal carbon chain are preferable, alkanediol solvents are more preferable, and 1,2-hexanediol is more preferable.

  In the present invention, it is also possible to add another solvent for adjusting the viscosity and improving the discharge property. Other solvents include glycerin, diols at both ends, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, N-methyloxazolidinone, N-ethyloxazolidinone, γ-butyrolactone, ε-caprolactone, N, N-dimethyl-β -Methoxypropionamide and the like.

  In the present invention, a colorant can also be used. Examples of the colorant include dyes and pigments. These color materials may be used alone or in combination of two or more. In order to improve the water resistance and weather resistance of the printed material, it is preferable to use a pigment. The content of the coloring material is 0.1% to 20% by weight, preferably 1% to 10% by weight, more preferably 2% to 7% by weight, based on the total weight of the ink.

  In the case of using a dye, various dyes usually used for ink jet recording, such as a direct dye, an acid dye, a food dye, a basic dye, a reactive dye, a disperse dye, and a vat dye, can be used.

  More specifically, CI Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78 are used as cyan dyes. , 80, 82, 83, 90, 92, 93, 100, 012, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154 , 158, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, 249, CI Direct Blue 1,2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249, CI Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13 , 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34,37, 38, 39, 40, 41, 43, 44, 46, CI Food Blue 1, 2, CI Basic Blue 9, 25, 28, 29, 44 and the like. CI Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 75, 77, 80, 82, 85, 87 as magenta dye , 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180 , 183, 184, 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322, CI Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, CI Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11 , 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42 , 43, 45, 46, 49, 50, 58, 59, 63, 64, CI Food Red 7, 9, 14 and the like. CI Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79 , 98, 99, 110, 111, 127, 131, 135, 142, 162, 164, 165, CI Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142, 144, Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42, CI Food Yellow 3, 4 and the like. Examples of black dyes include C. I. Direct Black 1, 7, 19, 32, 51, 71, 108, 146, 154, 166 and the like.

  CI Acid Green 7, 12, 25, 27, 35, 36, 40, 43, 44, 65, 79, CI Direct Green 1, 6, 8, 26, 28, as dyes other than cyan, magenta, yellow and black 30, 31, 37, 59, 63, 64, CI Reactive Green 6, 7, CI Direct Violet 2, 48, 63, 90, CI Reactive Violet 1, 5, 9, 10, etc.

  When a pigment is used, either an inorganic pigment or an organic pigment can be used. Examples of inorganic pigments include titanium oxide, zinc white, zinc sulfide, lead white, calcium carbonate, precipitated barium sulfate, white carbon, alumina white, kaolin clay, talc, bentonite, black iron oxide, cadmium red, brown rice, molybdenum red, Molybdate orange, chrome vermilion, yellow lead, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, titanium cobalt green, cobalt green, cobalt chrome green, Victoria green, ultramarine, bitumen, cobalt blue, cerulean blue , Cobalt silica blue, cobalt zinc silica blue, manganese violet, cobalt violet and the like.

  Examples of organic pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, quinophthalone pigments, dye lake pigments, and fluorescent pigments.

  More specifically, examples of cyan pigments include C. I. Pigment Blue 1, 2, 3, 15: 1, 15: 3, 15: 4, 15: 6, 16, 21, 22, 60, 64 and the like. CI Pigment Red 5, 7, 9, 12, 31, 48, 49, 52, 53, 57, 97, 112, 120, 122, 146, 147, 149, 150, 168, 170, 177, 178 as magenta pigments , 179, 184, 188, 202, 206, 207, 209, 238, 242, 254, 255, 264, 269, 282, CI Pigment Violet 19, 23, 29, 30, 32, 36, 37, 38, 40, 50 etc. are mentioned. CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128 , 129, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213 and the like.

  Examples of the black pigment include carbon black produced by the furnace method and the channel method. For example, these carbon blacks have a primary particle size of 11 to 40 nm, a specific surface area by BET method of 50 to 400 m2 / g, a volatile content of 0.5 to 10%, a pH value of 2 to 10, etc. Is preferred. The following are mentioned as a commercial item which has such a characteristic. For example, No.33, 40, 45, 52, 900, 2200B, 2300, MA7, MA8, MCF88 (Mitsubishi Chemical), RAVEN1255 (Colombian Carbon), REGA330R, 400R, 660R, MOGUL L, ELFTEX415 ( As described above, manufactured by Cabot), Nipex90, Nipex150T, Nipex160IQ, Nipex170IQ, Nipex75, Printex85, Printex95, Printex90, Printex35, PrintexU (above, manufactured by Evonik Degussa) and the like can be preferably used.

  CI Pigment Green 7, 10, 36, CI Pigment Brown 3, 5, 25, 26, CI Pigment Orange 2, 5, 7, 13, 14, 15, 16, 24 other than cyan, magenta, yellow, and black , 34, 36, 38, 40, 43, 62, 63, 64, 71 and the like.

  When these pigments are used, it is preferable to use them dispersed in an ink medium in order to maintain long-term ink stability. As a method for dispersing the pigment, there are a method in which the pigment is surface-modified by oxidation treatment or the like and the pigment is dispersed without a dispersant, and a method in which the pigment is dispersed using a surfactant or resin as a dispersant. In order to obtain a more stable ink, it is preferable to disperse the pigment using a dispersion resin.

  Examples of the pigment dispersion resin include an acrylic resin, a styrene acrylic resin, a maleic acid resin, a styrene maleic resin, an α-olefin maleic resin, a urethane resin, and an ester resin. Among these, it is preferable to use an acrylic resin or a styrene acrylic resin.

  The acid value of the pigment dispersion resin is preferably 50 to 400 mgKOH / g. If the acid value is less than 50 mgKOH / g, the resin is difficult to dissolve in water, and the viscosity of the ink increases, which may affect ejection. Moreover, even when it is larger than 400 mgKOH / g, the interaction between the resins may be strengthened and the viscosity may be increased. The acid value of the pigment dispersion resin is more preferably 100 to 350 mgKOH / g, and further preferably 150 to 300 mgKOH / g.

  The weight average molecular weight of the pigment-dispersed resin is preferably 5,000 to 100,000. When the molecular weight is 5000 or less, the dispersion stability may be lowered, and when the molecular weight is 100000 or more, ejection may be affected. More preferably, the molecular weight is 10,000 to 50,000, and still more preferably the molecular weight is 15,000 to 30,000.

  The weight ratio of the pigment to the pigment dispersion resin is preferably 2/1 to 100/1. When the ratio of the pigment dispersion resin is larger than 2/1, the viscosity of the ink tends to increase. On the other hand, if it is less than 100/1, the dispersibility may be lowered and the stability may be lowered. The ratio of the pigment to the pigment dispersion resin is more preferably 4/1 to 50/1, further preferably 5/1 to 25/1, and most preferably 10/1 to 20/1.

  In addition to the above components, the ink of the present invention may be appropriately added with additives such as antifoaming agents, thickeners, pH adjusters, preservatives, etc. in order to obtain inks having desired physical properties as required. can do. The additive amount of these additives is 0.01% or more and 10% by weight or less, preferably 0.05% or more and 5% by weight or less, more preferably 0.1% or more and 3% by weight or less with respect to the total mass of the ink.

  The ink of the present invention may be used in a single color, but can also be used as an ink set in which a plurality of colors are combined according to the application. The combination is not particularly limited, but a full color image can be obtained by using three colors of cyan, magenta, and yellow. Moreover, black feeling can be improved by adding black ink, and the visibility of a character etc. can be raised. Furthermore, color reproducibility can be improved by adding colors such as orange and green. When printing on a print medium other than white, a clear image can be obtained by using white ink together.

  When the ink of the present invention is used in a combination of cyan, magenta and yellow with pigments as colorants, CI Pigment Blue 15: 3, 15: 4 as cyan pigments, CI Pigment Red 122, 202, 209, 269, as magenta pigments CI Pigment Violet 19, High color reproducibility can be obtained by using a combination of pigments selected from CI Pigment Yellow 74, 120, 150, 155, and 185 as a yellow pigment.

  When printing is performed with an ink jet printing apparatus using the ink of the present invention, printing is preferably performed while heating the printing medium to 40 to 80 ° C. By printing while heating, the ink droplets are dried immediately after landing on the print medium, so that bleeding is unlikely to occur and a high-quality printed matter can be obtained.

Known printing media can be used for printing with the ink jet ink of the present invention. For example, paper media such as high-quality paper, coated paper, art paper, cast paper, synthetic paper, and ink-jet paper, and plastic media such as polyvinyl chloride sheets, PET films, and PP films. These may have a smooth print medium surface or an uneven surface, or may be transparent, translucent, or opaque. Further, two or more of these print media may be bonded to each other. Furthermore, a peeling adhesive layer or the like may be provided on the opposite side of the printing surface, or an adhesive layer or the like may be provided on the printing surface after printing.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, “parts” and “%” represent “parts by weight” and “% by weight” unless otherwise specified.

(Production example of pigment dispersion)
20 parts of Pigment Blue 15: 3 as pigment, 6 parts of pigment dispersion resin (styrene acrylic resin, acid value 200 mgKOH / g), 74 parts of water are mixed and predispersed with a disper, then 1800 g of zirconia beads with a diameter of 0.5 mm This dispersion was performed for 2 hours using a 0.6 L capacity dyno mill filled with a pigment dispersion liquid (Cyan). Pigment Blue 15: 3 was changed to Pigment Red 122, and a pigment dispersion (Magenta) was obtained in the same manner. Pigment Blue 15: 3 was changed to Pigment Yellow 120, and a pigment dispersion (Yellow) was obtained in the same manner. Pigment Blue 15: 3 was changed to Pigment Black 7, and a pigment dispersion (Black) was obtained in the same manner.

(Example 1)
Add 20 parts of pigment dispersion (Cyan), 10 parts of diethylene glycol methyl ethyl ether, 10 parts of 1,2-hexanediol, 0.2 part of Tegowet 280, and 40 parts of water into the mixing vessel with stirring with a disper in order, sufficiently uniform Stir until. Thereafter, filtration with a membrane filter was performed to remove coarse particles that would cause clogging of the head, and the cyan ink for inkjet according to the present invention was prepared. Similarly, magenta ink, yellow ink, and black ink were prepared using pigment dispersions (Magenta, Yellow, Black). The prepared inkjet ink was filled into VersaCAMM VS-540 (an inkjet printer manufactured by Roland DG), and printing evaluation was performed using a polyvinyl chloride sheet as a base material.

(Dryness evaluation)
The number of printing passes was changed with the printer, and solid printing was performed at a printing rate of 100%. The occurrence of mottling in each printed material was observed, and the drying property was evaluated. The evaluation criteria were as follows.
A: Mottling does not occur when printing with 4 passes
B: No mottling when printing with 8 passes
C: Mottling does not occur when printing with 16 printing passes
D: No mottling when printing with 32 printing passes
E: Mottling occurs even when printing with 32 printing passes

(Print quality evaluation)
With the above printer, the solid color (cyan, magenta, yellow, black) solid part (printing rate 100%) and the secondary color (red, green, blue) solid part (printing rate 200%) borders should touch each other. Printing was done. The print quality was evaluated by observing bleeding at the boundary portion of the printed material and white spots in the solid portion. The evaluation criteria were as follows.
A: Bleeding is not observed at the boundary between secondary colors, and no white spots are observed in the solid solid part.
B: Bleeding is not observed at the boundary between the secondary color and the single color, and no white spots are observed in the solid solid portion.
C: Bleeding is not seen at the boundary between single colors, and no white spots are seen in the solid solid part
D: Slight bleeding was observed at the boundary between single colors, or white spots in the single color solid portion were slightly observed.
E: Bleeding was remarkably observed at the boundary between single colors, or many white spots were observed in a solid solid portion.

(Discharge stability evaluation)
The above printer performed solid printing with a printing width of 1 m, printed a nozzle check pattern every printing length of 1 m, counted the number of missing nozzles, and evaluated the number. The evaluation criteria were as follows.
A: No printing missing at 5m printing length
B: No missing nozzle with printing length 3, 4m
C: No missing nozzle with printing length of 1 or 2m
D: No more than 10 nozzles with 1m printing length
E: 11 or more nozzles with a printing length of 1m

(Examples 2 to 25, Comparative Examples 1 to 8)
An ink was prepared in the same manner as in Example 1 using the raw materials shown in Table 1, and the ink was evaluated.

  It was confirmed that the ink compositions of the examples can obtain high evaluations for drying properties, printing quality, and ejection stability. In Example 25, it was confirmed that the durability of the printed matter was improved by using a binder resin.

On the other hand, in Comparative Examples 1 and 2, since the surfactant was not used, the discharge stability was poor, and the wettability with respect to the base material was low, so that the printing quality was also deteriorated. In Comparative Examples 3 and 4, an acetylenic diol surfactant was used, but the effect of improving the ejection stability was low and sufficient performance could not be obtained. In Comparative Examples 5 and 6, since the solvent B was not included, the ink did not spread and spread on the base material, and white spots were generated. In Comparative Examples 7 and 8, since the solvent A was not included, the drying property was slow, and slight bleeding occurred at the boundary between colors.

Claims (7)

At least an organic solvent, a surfactant, and water. As the organic solvent, at least (A) a water-soluble organic solvent having a boiling point of 100 ° C. to 180 ° C. and (B) a boiling point of 200 ° C. to 280 ° C. and a surface An aqueous inkjet ink comprising an organic solvent having a tension of 20 mN / m or more and 30 mN / m or less, wherein the surfactant is a polysiloxane surfactant. 2. The water-based inkjet ink according to claim 1, wherein the surfactant is selected from the general formula 1 or 2.
[General formula 1]

(In the formula, a represents an integer of 1 to 500, b represents an integer of 0 to 0. R1 represents an alkyl group or an aryl group. R2 represents the following (A), (B), (C), (D) And at least one of R2 includes (A).
(A)

(c represents an integer of 1 to 20, d represents an integer of 0 to 50, e represents an integer of 0 to 50. R3 represents a hydrogen atom or an alkyl group. R4 represents a hydrogen atom, an alkyl group or an acyl group. Is shown.)
(B)

(f represents an integer of 2 to 20. R5 represents any one of a hydrogen atom, an alkyl group, an acyl group, and an ether group having a dimethylpropyl skeleton.)
(C)

(g is an integer of 2-6, h is an integer of 0-20, i is an integer of 1-50, j is an integer of 0-10, k is an integer of 0-10. R6 is a hydrogen atom, an alkyl group Represents any of acyl groups.)
(D) an alkyl group or an aryl group)
[General formula 2]

(In the formula, l represents an integer of 10 to 80. R7 is represented by the following substituent (E).
(E)

(m is an integer of 1 to 6, n is an integer of 0 to 50, o is an integer of 0 to 50, and n + o is an integer of 1 or more. R8 is a hydrogen atom or a carbon number of 1 to 6 An alkyl group or a (meth) acryl group.)) 3. The water-based inkjet ink according to claim 2, further comprising a compound represented by the general formula 3 as the surfactant.
[General formula 3]

(P and q are integers of 1 or more, p + q is represented by an integer of 3 to 50, R9 is represented by the following substituent (F), and R10 is represented by an alkyl group having 1 to 6 carbon atoms. )

(R is an integer of 1 to 6, s is an integer of 0 to 50, t is an integer of 0 to 50, and s + t is an integer of 1 or more. R11 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Or (meth) acrylic group)   The water-based inkjet ink according to any one of claims 1 to 3, wherein the surfactant is contained in the ink in an amount of 0.5 to 3% by weight.   The water-soluble organic solvent (A) having a boiling point of 100 ° C or higher and 180 ° C or lower includes any one selected from propylene glycol monomethyl ether, methoxybutanol, and 3-methyl-3-methoxybutanol. The ink for water-based inkjets in any one of 1-4.   A printing method for performing printing by attaching ink droplets to a print medium while heating the print medium to 40 to 80 ° C, wherein the aqueous inkjet ink according to any one of claims 1 to 5 is used. An inkjet printing method. 7. The ink jet printing method according to claim 6, wherein the printing medium is a non-water-absorbing substrate or a hardly water-absorbing substrate.