JP2014205770A - Aqueous ink for inkjet - Google Patents

Abstract

[PROBLEMS] To provide an inkjet ink that 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 capable of obtaining a high-quality and durable image. provide. SOLUTION: 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. as the organic solvent, containing at least water-dispersible resin fine particles, an organic solvent, and water. An aqueous inkjet ink comprising an organic solvent having a surface tension of 20 mN / m or more and 30 mN / m or less. [Selection figure] None

Description

  INDUSTRIAL APPLICABILITY The present invention is an inkjet ink that is excellent in printability on a general printing substrate, particularly a substrate having low water absorption such as coated paper, art paper and vinyl chloride sheet, and can obtain a high-quality, durable image. Relates to the composition.

  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

  An object of the present invention is an ink jet which 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 which can obtain a high quality and durable image. Providing an ink composition.

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

  (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 tension of 20 mN / m to 30 mN / m contained in the ink. The total content of the organic solvent is 10 to 45% by weight.

In addition, the water-dispersible resin fine particles may include a crosslinkable monomer as a constituent component.
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.

In addition, the present invention relates to the above aqueous inkjet ink, wherein the organic solvent (B) 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 is an alkanediol solvent.
In addition, the water-dispersible resin particles include the sulfonic acid group-containing monomer as a constituent component.

Further, the present invention relates to the above-mentioned water-based ink jet ink, further comprising a surfactant, wherein the surfactant is a polysiloxane surfactant.
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, an ink jet ink that is excellent in printability to a general printing substrate, particularly a substrate having low water absorption such as coated paper, art paper or vinyl chloride sheet, and can obtain a high quality and durable image. It has become possible to provide a composition.

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

  In the present invention, the water-dispersible resin fine particles and the organic solvent as a water-soluble organic solvent (solvent A) having a boiling point of 100 ° C. or higher and 180 ° C. or lower 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 drying speed during printing, the print quality, and the durability of the printed matter are improved. The main components of the present invention are described below.

  Water-soluble resins and water-dispersible resin fine particles are widely known as binder resins for water-based inks. However, in the present invention, by using water-dispersible resin fine particles as a binder resin, the printed matter can be improved in resistance and printed. Improves wetting and spreading after ink droplets have landed, improving print quality. Since the water-soluble resin is dissolved in the ink, the resins may be entangled with each other, impairing the fluidity of the ink, and the wetting and spreading to the printing medium may be deteriorated. On the other hand, since the water-dispersible resin fine particles are not entangled with each other, the ink flows and spreads, and a printed matter with good solid filling can be obtained. Further, since the water-dispersible resin fine particles have a high molecular weight as compared with the water-soluble resin, high resistance can be obtained.

  Examples of the water-dispersible resin fine particles used in the present invention include acrylic resins, urethane resins, styrene butadiene resins, vinyl chloride resins, and polyolefin resins. It is preferable to use water-dispersible resin fine particles of acrylic resin from the viewpoints of ink stability and printed material resistance.

  In the present invention, the dispersion stability of the resin fine particles in the ink can be improved by including a crosslinkable monomer as a constituent of the water-dispersible resin fine particles. If the dispersion stability is poor, when the ink droplets are dried on the printing medium and the solvent ratio is high, the resin fine particles are aggregated and solidified, so that the ink droplets do not wet and spread on the printing medium. Therefore, the printed material may have white spots and may have low image quality.

  The crosslinkable monomer is introduced into the resin fine particles by being used in combination with other raw material monomers during the production of the resin fine particles. The content of the crosslinkable monomer in the resin fine particles is preferably 0.1 to 10% by weight, more preferably 0.2 to 8%, and still more preferably 0.5 to 5%. When the content is within this range, the dispersion stability of the resin fine particles is good, and the ink can obtain a high-quality printed matter. When the content is more than 10%, the film formability of the resin fine particles is lowered, and the printed matter may be lowered in resistance.

  Examples of the crosslinkable monomer include allyl (meth) acrylate, vinyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol (meth) ) Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate , Neopentyl glycol di (meth) acrylate, glycerin dimethacrylate, dimethylol tricyclodecane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate , Divinyl ben Monomers having two or more unsaturated groups such as divinyl adipate, diallyl adipate, diallyl isophthalate, diallyl phthalate, diallyl maleate, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acrylic Roxypropyltriethoxysilane, γ- (meth) acryloxypropyltributoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxy Alkoxysilyl group-containing unsaturated monomers such as methyltrimethoxysilane, γ- (meth) acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, N- Methylol (meth) acrylamide, N, N-dimethylol (meth) acrylamid Although methylol group-containing unsaturated monomers such as alkyl etherified -N- methylol (meth) acrylamide, but it is not particularly limited thereto. These can be used alone or in combination of two or more.

  Among the above crosslinkable monomers, a monomer having two allyl groups and an alkoxysilyl group-containing unsaturated monomer are preferable from the viewpoint of improving dispersion stability, and a monomer having two allyl groups Is more preferable.

  The dispersion stability of the resin fine particles can be further improved by including a sulfonic acid group-containing monomer as a constituent component in the water-dispersible resin fine particles used in the present invention. The content of the sulfonic acid group-containing monomer in the resin fine particles is preferably 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, and still more preferably 0.5 to 5% by weight. If the content is within this range, the dispersion stability of the resin fine particles is good, and the ink can obtain a high-quality printed matter. When the content is more than 10%, the dispersion stability of the resin fine particles may be lowered and the water resistance of the printed matter may be lowered.

  Examples of sulfonic acid group-containing monomers include styrene sulfonic acid, sodium styrene sulfonate, ammonium styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium 2-acrylamido-2-methylpropane sulfonate, and methallyl sulfonic acid. , Methallyl sulfonic acid, sodium methallyl sulfonate, allyl sulfonic acid, sodium allyl sulfonate, ammonium allyl sulfonate, vinyl sulfonic acid, allyloxybenzene sulfonic acid, sodium allyloxybenzene sulfonate, ammonium allyloxybenzene sulfonate, etc. Is mentioned.

  By increasing the glass transition temperature (Tg) of the water-dispersible resin fine particles, it is possible to improve resistance such as abrasion resistance and chemical resistance, preferably 50 to 120 ° C, more preferably 80 to 100 ° C. It should be in the range of ° C. When the temperature is lower than 50 ° C., sufficient resistance cannot be obtained, and the ink coating film may be peeled off from the printed matter in practical use. In addition, when the temperature is higher than 120 ° C., the coating film becomes very hard, and cracking and cracking may occur on the printed surface when the printed material is bent.

  The content of the above water-dispersible resin fine particles in the ink is in the range of 2% to 30% by weight, preferably in the range of 3% to 20% by weight, based on the total mass of the ink in terms of solid content. More preferably, it is in the range of 6% to 15% by weight.

  In the present invention, a water-soluble organic solvent (solvent A) having a boiling point of 100 ° C. to 180 ° C. and an organic solvent (solvent) having a boiling point of 200 ° C. to 280 ° C. and a surface tension of 20 mN / m to 30 mN / m. By combining B), it is possible to satisfy the dryness, print quality and durability at a high level. This principle can be considered as follows. By using the solvent A having a low boiling point, drying after ink droplets have landed on the printing medium can be accelerated. Since the solvent A and water in the ink are volatilized, the high-boiling point solvent B remains in the ink droplets. Since solvent B has a low surface tension, it wets and spreads on the printing medium, and a uniform coating film is formed in the solid printing portion. In addition, since the solvent A and water in the ink are immediately dried, the viscosity of the ink droplet is increased, and color mixing is difficult to occur even when the ink comes into contact with other colors of ink. Ink that does not contain solvent A and is slow to dry has a very low viscosity even after landing on the printing medium, so it easily mixes colors, and blurring occurs, resulting in poor print quality. In addition, the ink droplets are wet and the contact area with the printing surface is increased, so that the adhesion is improved and the resistance is improved.

  The amount of solvent A and solvent B added to the ink is preferably 10 to 45% by weight as the total amount of solvent A and 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 ratio (weight ratio) of solvent A and solvent B is preferably solvent A: solvent B = 1: 5 to 5: 1, more preferably solvent A: solvent B = 1: 4 to 4: 1. Preferably, solvent A: solvent B = 1: 3 to 2: 1, and 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.

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。 In the present invention, a polysiloxane surfactant can be added as a surfactant in order to improve ejection stability by adjusting the surface tension. It is preferable to use the compounds represented by the general formulas 1 to 3 as the surfactant. A compound represented by general formula 1 or 2 is more preferable, and a compound represented by general formula 1 is still more preferable. The addition amount of the surfactant is preferably 0.1 to 5%, more preferably 0.5 to 3%, still more preferably 0.8% to 2%, and most preferably 1 to 1.5%.
[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 7]

(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, 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 color material is 0.1% or more and 20% or less, preferably 1% or more and 10% or less, more preferably 2% or more and 7% or less with respect to the total mass 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 addition 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 water-dispersible resin fine particles A)
In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and refluxing vessel, 40 parts of ion-exchanged water and 0.2 part of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant were charged, and 2-ethylhexyl was separately added. 40 parts of acrylate, 57 parts of methyl methacrylate, 2 parts of dimethylacrylamide, 1 part of acrylic acid, 53 parts of ion-exchanged water and 1.8 parts of Aqualon KH-10 (Daiichi Kogyo Seiyaku) as a surfactant were mixed in advance. An additional 1% of the emulsion was added. After raising the internal temperature to 60 ° C. and sufficiently purging with nitrogen, 10 parts of a 5% aqueous solution of potassium persulfate and 20 parts of a 1% aqueous solution of anhydrous sodium bisulfite were added to initiate polymerization. After maintaining the reaction system at 60 ° C. for 5 minutes, while maintaining the internal temperature at 60 ° C., the remaining pre-emulsion, 5% aqueous solution of potassium persulfate, and the remaining 1% aqueous solution of anhydrous sodium bisulfite were added over 1.5 hours. The mixture was added dropwise and stirring was continued for another 2 hours. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. Diethylaminoethanol was added to adjust the pH to 8.5, and the solid content was adjusted to 40% with ion-exchanged water to obtain a solution of water-dispersible resin fine particles A. The calculated glass transition temperature of the obtained water-dispersible resin fine particles A is 40 ° C.

(Production example of water-dispersible resin fine particles B)
Resin synthesis was carried out in the same manner as the water-dispersible resin fine particles A except that 57 parts of methyl methacrylate in Pigment-dispersed resin production example 1 was changed to 56 parts of methyl methacrylate and 1 part of diallyl phthalate. A solution was obtained. The calculated glass transition temperature of the obtained water-dispersible resin fine particles B is 40 ° C.

(Production example of water-dispersible resin fine particles C)
In the same manner as in the water-dispersible resin fine particles A, except that 57 parts of methyl methacrylate in Pigment-dispersed resin production example 1 was changed to 56 parts of methyl methacrylate, 1 part of diallyl phthalate, and 1 part of acrylic acid to 1 part of sodium styrenesulfonate. Resin synthesis was performed to obtain a solution of water-dispersible resin fine particles C. The calculated glass transition temperature of the obtained water-dispersible resin fine particles B is 40 ° C.

(Production example of water-dispersible resin fine particles D)
40 parts of 2-ethylhexyl acrylate of Pigment Dispersion Resin Production Example 1 is 15 parts of 2-ethylhexyl acrylate, 57 parts of methyl methacrylate is 81 parts of methyl methacrylate, 1 part of diallyl phthalate, 1 part of acrylic acid is 1 part of sodium styrenesulfonate Resin synthesis was carried out in the same manner as in the case of the water-dispersible resin fine particles A except that the amount was changed to obtain a solution of the water-dispersible resin fine particles C. The calculated glass transition temperature of the obtained water-dispersible resin fine particles B is 80 ° C.

(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)
While stirring 20 parts of the pigment dispersion (Cyan), 20 parts of the water-dispersible resin fine particle A solution, 10 parts of diethylene glycol methyl ethyl ether, 10 parts of 1,2-hexanediol, and 40 parts of water into the mixing vessel with a disper It put in one by one and stirred until it became uniform enough. 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.

(Resistance evaluation)
The printed material was rubbed with a cotton swab soaked in ethanol and subjected to a resistance test. The evaluation was performed based on the number of rubbing until the ink was peeled off and the ground was visible. The evaluation criteria were as follows.
A: 51 or more rubbing cycles until the substrate is visible
B: 41-50 rubbing times until the base is visible
C: 21-40 rubbing cycles until the substrate is visible
D: The rubbing number of times until the base is visible is 11-20 times
E: 10 times or less of rubbing until the base is visible

(Examples 2 to 23, Comparative Examples 1 to 6)
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 inks of the examples were highly evaluated for all of drying properties, print quality, and printed material resistance. In Examples 19 to 21, when water-dispersible resin fine particles having a Tg of 80 ° C. were used, it was confirmed that higher resistance was obtained. In Examples 22 and 23, it was confirmed that the discharge stability was improved by using a surfactant.

  On the other hand, in Comparative Examples 1 and 2, since water-dispersible resin fine particles are not used, resistance is low, and there is no effect of suppressing mottling due to film formation of water-dispersible resin fine particles, and the surface flows during drying. The dryness was also poor. In Comparative Examples 3 and 4, since the solvent B was not included, the ink did not wet and spread on the base material, and thus the white spots were generated. Furthermore, since the coating film was not uniform, the resistance was also lowered. In Comparative Examples 5 and 6, since solvent A was not included, drying was slow and bleeding occurred at the boundary between colors.

Claims (9)

  At least water-dispersible resin fine particles, an organic solvent, and water, and 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 An aqueous ink-jet ink comprising an organic solvent having a surface tension of 20 mN / m or more and 30 mN / m or less at a temperature of ℃ or less.   (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 tension of 20 mN / m to 30 mN / m, contained in the ink The water-based inkjet ink according to claim 1, wherein the total amount of the organic solvent is 10 to 45% by weight.   3. The aqueous inkjet ink according to claim 1, wherein the water-dispersible resin fine particles contain a crosslinkable monomer as a constituent component.   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. 1-3. The water-based inkjet ink in any one of 1-3.   The aqueous solvent according to any one of claims 1 to 4, wherein the organic solvent (B) having a boiling point of 200 ° C to 280 ° C and a surface tension of 20 mN / m to 30 mN / m is an alkanediol solvent. Ink for ink jet.   6. The water-based inkjet ink according to claim 1, wherein the water-dispersible resin fine particles contain a sulfonic acid group-containing monomer as a constituent component.   The aqueous inkjet ink according to claim 1, further comprising a surfactant, wherein the surfactant is a polysiloxane surfactant.   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 7 is used. An inkjet printing method. The inkjet printing method according to claim 8, wherein the printing medium is a non-water-absorbing substrate or a hardly water-absorbing substrate.