WO2018123739A1

WO2018123739A1 - Aqueous ink composition for ink-jet printing

Info

Publication number: WO2018123739A1
Application number: PCT/JP2017/045578
Authority: WO
Inventors: 員揮森安; 恵理高橋
Original assignee: サカタインクス株式会社
Priority date: 2016-12-27
Filing date: 2017-12-19
Publication date: 2018-07-05
Also published as: JP6868392B2; JP2018104582A

Abstract

The present invention addresses the problem of providing an aqueous ink composition for ink-jet printing which, even when printed on coated paper for ink-jet printing or on treated paper for ink-jet printing, causes no mottling and which is excellent in terms of delivery stability and storage stability. Provided as a solving means is an aqueous ink composition for ink-jet printing which comprises (a) an alkali-soluble resin having acid groups, some or all of which have been neutralized with a basic compound, (b) 0.01-10 mass% free amino alcohol, (c) a pigment, (d) a water-soluble organic solvent, and (e) water.

Description

Water-based inkjet ink composition

The present invention relates to an aqueous inkjet ink composition that does not cause motering even when printed on inkjet coated paper and inkjet treat paper, and is excellent in ejection stability and storage stability.

The ink jet printing method is a printing / recording method in which ink droplets are directly ejected from a very fine nozzle onto a printing / recording substrate and adhered to obtain characters and images.
The water-based inkjet printing method was once considered unsuitable for the production of a large amount of printed matter due to problems such as a long print time due to the printing head being a scanning type and slow drying of an aqueous medium.
However, on the other hand, it does not require a plate making process like a normal printing method, and even if it includes an electrophotographic method, it has the advantage that it can be printed with a very simple device configuration. It was mostly used at home.

Therefore, if problems such as the time required for printing and drying can be solved, it is considered that there is sufficient value in competition with other printing methods even in industrial applications such as office and commercial printing. For these reasons, in order to use the inkjet printing method for industrial purposes, recently, a technology for actively applying high-speed printing and low-cost printing paper from both the printing apparatus and ink has been studied. .
In industrial applications, use of low-absorbency media such as inkjet coated paper and inkjet treat paper as well as uncoated paper such as cheap plain paper and ordinary offset paper is also considered as a printing substrate. Has been. Since such media have a lower surface tension than media such as uncoated paper, the contact angle of the ink droplets with the media is large, and it is difficult for the ink droplets to wet and spread on the media when they land. Dots do not expand sufficiently, lack of density, and have a narrow color gamut.
In addition, the ink itself must also have storage stability, which is the ink performance required by the original ink jet printing method.

Examples of the ink composition for inkjet used in these include an anionic microencapsulated pigment formed by coating an organic pigment or carbon black with an organic polymer compound containing an anionic group neutralized with a base, and An aqueous inkjet ink composition containing a water-soluble anionic surfactant and / or a nonionic surfactant having an HLB value of 14 or more (see, for example, Patent Document 1), and an aqueous inkjet containing crosslinked polymer particles for inkjet recording An ink composition (see, for example, Patent Document 2) is disclosed. However, in any of the water-based ink-jet ink compositions, when the recording medium is ink-jet coated paper or ink-jet treat paper, there is a problem that motering occurs at a high printing rate.

Japanese Patent Laid-Open No. 10-140065 JP 2008-150535 A

It is an object of the present invention to provide an aqueous inkjet ink composition that does not cause motering even when printed on inkjet coated paper and inkjet treat paper, and is excellent in ejection stability and storage stability. To do.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have invented the following aqueous inkjet ink composition.
That is, the present invention
1. a. Alkali-soluble resin obtained by neutralizing a part or all of acid groups with a basic compound b. 0.01-10% by mass of free amino alcohol
c. Pigment d. Water-soluble organic solvent e. A water-based inkjet ink composition containing water a to e.
2. 2. The aqueous inkjet ink composition according to 1, wherein the basic compound is an amino alcohol.
3. 3. The water-based inkjet ink composition according to 1 or 2, wherein the pigment is a resin-coated pigment coated with an alkali-soluble resin and / or a cross-linked resin-coated pigment obtained by crosslinking the resin-coated pigment with a bifunctional or higher functional crosslinking agent.
4). 4. The aqueous inkjet ink composition according to any one of 1 to 3, wherein the alkali-soluble resin contains a structural unit derived from stearyl (meth) acrylate and / or lauryl (meth) acrylate in the resin.
5). 5. The aqueous inkjet ink composition according to any one of 1 to 4, wherein the content of the water-soluble organic solvent is 10 to 60% by mass in the aqueous inkjet ink composition.

According to the water-based inkjet ink composition of the present invention, the ink composition itself is excellent in storage stability, and even when printed on inkjet coated paper and inkjet treat paper, it does not cause motering and has ejection stability. Can exhibit a remarkable effect.

The present inventors have studied a water-based inkjet ink composition containing a pigment, an alkali-soluble resin, a basic compound that neutralizes part or all of the alkali-soluble resin, and a water-soluble organic solvent. By containing 0.01 to 10% by mass of free amino alcohol, preferably, the amino alcohol is used as a basic compound for neutralizing a part or all of the alkali-soluble resin, and then the free amino alcohol is used in the ink composition. It has been found that the above-mentioned problems can be solved by containing 0.01 to 10% by mass of alcohol, and the present invention has been solved.

Hereinafter, the aqueous inkjet ink composition of the present invention will be described.
<A. Alkali-soluble resin in which part or all of acid groups are neutralized with basic compound>
As the alkali-soluble resin in the present invention, known ones conventionally used in water-based inkjet ink compositions can be used.
The monomer component constituting such an alkali-soluble resin includes a monomer having a carboxyl group, a monomer containing a hydrophobic group for improving the adsorptivity with a pigment, and other polymerizable units. Composed of a mass.

Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, maleic anhydride, Maleic acid monoalkyl ester, citraconic acid, citraconic anhydride, citraconic acid monoalkyl ester and the like can be used.

The monomer containing a hydrophobic group for improving the adsorptivity with the pigment is preferably a (meth) acrylate having a long-chain alkyl group having 6 to 20 carbon atoms, particularly 2-ethylhexyl (meta). ) Acrylate, octyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxystearyl (meth) acrylate, etc. are more preferable. Toluene or the like can be used.

Other monomers that can be polymerized are those that can be used as long as the properties of the alkali-soluble resin are not impaired, and include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. (Meth) acrylic acid such as isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, hydroxyethyl (meth) acrylate, acrylamide, N-methylolacrylamide, cyclohexyl (meth) acrylate, Benzyl (meth) acrylate and the like can be used.

The acid value of the alkali-soluble resin is preferably 40 to 300 mgKOH / g, more preferably 70 to 250 mgKOH / g. If the acid value of the alkali-soluble resin is lower than 40 mgKOH / g, the dispersion stability of the aqueous dispersion of the resulting alkali-soluble resin may be lowered. On the other hand, if it is higher than 300 mgKOH / g, the hydrophilicity becomes too high. Storage stability and water resistance may decrease.
The molecular weight of the alkali-soluble resin is usually preferably 3,000 to 200,000, and more preferably 10,000 to 50,000. When the weight average molecular weight of the alkali-soluble resin is less than 3,000, the dispersion stability of the pigment and the scratch resistance of the resulting printed matter tend to decrease. Absent.
The blending amount of the alkali-soluble resin is preferably 10 to 100 parts by mass with respect to 100 parts by mass of the pigment described below.

The acid value is a theory obtained by arithmetically determining the number of mg of potassium hydroxide theoretically required to neutralize 1 g of the alkali-soluble resin based on the composition of the monomer used to synthesize the alkali-soluble resin. The acid value.
The weight average molecular weight can be measured by a gel permeation chromatography (GPC) method. As an example, chromatography can be performed using Water 2690 (manufactured by Waters) as a GPC apparatus and PLgel 5 μm MIXED-D (manufactured by Agilent Technologies) as a column, and the weight average molecular weight in terms of polystyrene can be obtained.

(Basic compound)
Examples of basic compounds that neutralize alkali-soluble resins include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, triethylamine, monoethanolamine, triethanolamine, N, N-dimethylethanolamine, N, N- Examples include one or more organic basic compounds such as diethylethanolamine, N, N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, and triethylenediamine. Among these, from the viewpoint of preventing the occurrence of motoring, monoethanolamine, triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine Amino alcohols such as are preferred.

<B. Free amino alcohol>
The free amino alcohol used in the present invention is a basic compound (amino alcohol) in which the acid group of the alkali-soluble resin is not neutralized, and can be selected from the same group of amino alcohols as the amino alcohol.
The blending amount of the free amino alcohol is 0.01 to 10% by mass, preferably 1.0 to 5.0% by mass in the aqueous inkjet ink composition of the present invention. When the amount of the free amino alcohol is outside the range of 0.01 to 10% by mass, the occurrence of motoring cannot be prevented.

<C. Pigment>
The pigment used in the present invention may be coated with an alkali-soluble resin or may be coated, or may be a crosslinked resin-coated pigment in which a resin for coating the pigment is crosslinked.
The blending amount of the pigment is preferably 1 to 10% by mass in the aqueous inkjet ink composition of the present invention.
Examples of the pigment used include various inorganic pigments and organic pigments generally used in ink jet inks. Specifically, the inorganic pigment includes colored pigments such as titanium oxide, bengara, antimony red, cadmium yellow, cobalt blue, ultramarine blue, bitumen, carbon black, graphite, and the like (including achromatic pigments such as white and black). And extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Examples of the organic pigment include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. These may be used alone or in combination of two or more.
In particular, from the viewpoint of enabling a clear hue expression, C.I. I. Red pigments such as CI Pigment Red 5, 7, 12, 57: 1, 122, 146, 202, 242 and 282; I. Blue pigments such as CI Pigment Blue 1, 2, 15: 3, 15: 4, 16, 17, 60; I. Purple pigments such as Pigment Violet 19, 23; I. Pigment Yellow 12, 13, 14, 17, 74, 83, 93, 128, 139, 151, 154, 155, 180, 185, 213 and the like yellow pigments; C.I. I. Pigment Black 7 (carbon black), C.I. I. Pigment Green 7, 36, etc., green pigments, C.I. I. Orange pigments such as Pigment Orange 34 and 71 are preferable.

(Pigment coated with alkali-soluble resin)
Examples of the pigment coated with the alkali-soluble resin include the above-described pigment, an aqueous resin varnish obtained by dissolving an alkali-soluble resin in water in the presence of a basic compound, a pigment dispersant and the like as necessary, and various dispersers, For example, after dispersing carbon black using a ball mill, attritor, roll mill, sand mill, agitator mill or the like, an alkali-soluble resin is applied to the pigment surface by an acid precipitation method or an ion exchange means described in International Publication No. 2005/116147. A resin-coated pigment in which selenium is precipitated can be used.
When the alkali-soluble resin coated with the obtained pigment is neutralized with a basic compound, 50 to 100% of the acid value of the alkali-soluble resin is the above basic compound. It is preferable that they are summed.

(Crosslinked resin-coated pigment)
Examples of the cross-linked resin-coated pigment include a pigment, an aqueous resin varnish obtained by dissolving an alkali-soluble resin in water in the presence of a basic compound, and a pigment dispersant as necessary. After dispersing the pigment using a lighter, roll mill, sand mill, agitator mill or the like, an alkali-soluble resin is applied to the pigment surface by an acid precipitation method or an ion exchange method or a phase inversion emulsification method described in WO 2005/116147. Then, the pigment obtained by precipitating the alkali-soluble resin on the surface of the obtained pigment is converted to 50-100% of the acid value of the alkali-soluble resin to improve the basic compound, particularly for improving motering. Neutralize with alcohol, re-disperse in water using various dispersers (high-speed stirrer, etc.), then add a bifunctional or higher functional cross-linking agent at 50-80 ° C Heated, available to those obtained by cross-linking.

The bifunctional or higher functional crosslinking agent used for the production of the crosslinked particles is used for appropriately crosslinking the alkali-soluble resin. The cross-linking agent of the present invention is a cross-linking agent having two or more reactive functional groups, and the molecular weight of the cross-linking agent is in the range of 100 to 2,000 from the viewpoint of ease of reaction and storage stability. It is preferable that As the reactive functional group, one or more selected from the group consisting of an epoxy group, a hydroxyl group, and an aridine group are preferably exemplified. Of these, an epoxy group is preferable from the viewpoint of viscosity and tolerance, and a bifunctional epoxy compound is more preferable.
Specific examples of the epoxy compound having two or more functions include Epolite 40E, 100E, 200E, 400E, 70P, 200P, 400P, 1500NP, 1600, 80MF (manufactured by Kyoeisha Chemical Co., Ltd.), Denacol EX-201, EX-211 , EX-212, EX-313, EX-314, EX-321, EX-411, EX-421, EX-512, EX-521, EX-611, EX-612, EX-614, EX-614B, EX -622 (manufactured by Nagase ChemteX Corporation). The amount of the bifunctional or higher functional crosslinking agent is such that 50 to 100% of the acid value (acid group) of the alkali-soluble resin is neutralized with a basic compound and 10 to 100% of the remaining acid value (acid group). Preferably, it is used so that 50 to 100% is crosslinked.

<D. Water-soluble organic solvent>
A water-soluble organic solvent is used as an aqueous medium together with water.
The water is preferably ion-exchanged water or distilled water from which metal ions or the like have been removed.
By including a water-soluble organic solvent, it may be possible to impart more excellent ink jet printing suitability in terms of storage stability, ejection stability, ink flying property, and the like. Examples of such water-soluble organic solvents include monoalcohols, polyhydric alcohols, lower alkyl ethers of polyhydric alcohols, ketones, ethers, esters, nitrogen-containing compounds, and the like. These may be used alone or in combination of two or more.

Examples of the monoalcohols include methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonyl alcohol, n-decanol, and isomers thereof. , Cyclopentanol, cyclohexanol and the like. Preferably, alcohol having an alkyl group having 1 to 6 carbon atoms can be used.
Examples of the polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, neopentyl glycol, 1,2- Hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol, heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, glycerin, pentaerythritol, diethylene glycol, dipropylene Glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, thiodiglycol and the like can be used.
Examples of the lower alkyl ethers of the polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, and ethylene glycol. Isobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glyco The mono -n- butyl ether and the like can be used.
As the ketones, acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, cyclohexanone and the like can be used.
As the ethers, isopropyl ether, n-butyl ether, tetrahydrofuran, tetrahydropyran, butyl carbitol, 1,4-dioxane and the like can be used.
Examples of the esters include propylene carbonate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, ethyl butyrate, dibutyl phthalate, dioctyl phthalate, and ε-caprolactone and ε-caprolactam A cyclic ester such as can be used.
As the nitrogen-containing compounds, urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, octyl pyrrolidone and the like can be used.
The content of the water-soluble organic solvent is preferably 10 to 60% by mass, more preferably 15 to 45% by mass in the aqueous inkjet ink composition.
Specific examples of the water-soluble organic solvent include 1 to 40% by mass of glycerin and at least one 0 to 30 selected from butyl carbitol, 2-pyrrolidone, propylene glycol, diethylene glycol, and 1,2-pentanediol. A combination of mass% can be exemplified.

(Surfactant)
In the aqueous inkjet ink composition of the present invention, as a surfactant, an acetylene glycol compound represented by the formula (1), an HLB 4-15 compound obtained by adding ethylene oxide to an acetylenic diol compound, a silicon interface At least one selected from an activator and a fluorosurfactant may be used.
Formula (1)

Specific examples of the acetylene glycol compound represented by the formula (1) include Surfynol 104E, Surfinol 104H, Surfinol 104A, Surfinol 104BC, Surfinol 104DPM, Surfinol 104PA, Surfinol 104PG50, etc. manufactured by Air Products. Is mentioned.
Specific examples of the HLB 4-15 compound obtained by adding ethylene oxide to an acetylenic diol compound include Surfynol 420, Surfynol 440, Surfynol 465 manufactured by Air Products.
As the silicon-based surfactant and the fluorine-based surfactant, known ones conventionally used in water-based inkjet ink compositions can be used.
The content of the surfactant is preferably 0.1 to 3% by mass in the aqueous inkjet ink composition. If the surfactant content is less than 0.1% by mass, the dot expandability and the solid uniformity of the printed matter tend to be reduced. On the other hand, if it exceeds 3% by mass, the storage stability of the ink tends to deteriorate. This is not preferable.
The HLB represents a balance between a hydrophilic part and a hydrophobic part of a molecule used in the field of surfactants (hydrophile-lipophile balance), and has a value from 0 to 20, It can be said that the larger the value, the higher the hydrophilicity.
In the present invention, the HLB value defined by the following Griffin equation is used.
[Griffin formula]
HLB = 20 × total formula weight of hydrophilic part in surfactant / molecular weight of surfactant

(Additive)
Furthermore, the water-based inkjet ink composition of the present invention has a known resin emulsion, pigment dispersant, antifungal agent, rust inhibitor, thickener, antioxidant, ultraviolet absorber, and improved storage stability depending on the purpose. Additives such as an agent, an antifoaming agent, and a pH adjusting agent can also be added.

<Method for producing aqueous inkjet ink composition>
As a method for producing the aqueous inkjet ink composition of the present invention using the above components,
(1) After mixing an aqueous resin varnish obtained by dissolving an alkali-soluble resin in water in the presence of a pigment and a basic compound, and a pigment dispersant as necessary, various dispersers such as a ball mill, an attritor, a roll mill, A method of preparing a water-based inkjet ink composition by dispersing carbon black using a sand mill, an agitator mill or the like, and further adding the remaining materials (hereinafter referred to as production method 1).
(2) After dispersing the pigment by the above method, a resin-coated pigment in which an alkali-soluble resin is precipitated on the pigment surface is obtained by an acid precipitation method or an ion exchange means described in International Publication No. 2005/116147, The obtained resin-coated pigment is neutralized with a basic compound, re-dispersed in water using various dispersers (such as a high-speed stirrer), and the remaining materials are added to prepare an aqueous inkjet ink composition. Method (3) After dispersing the pigment by the above method (1), an alkali-soluble resin is precipitated on the pigment surface by an acid precipitation method, an ion exchange method described in International Publication No. 2005/116147, a phase inversion emulsification method, or the like. Next, neutralize 50-80% of the acid value of the alkali-soluble resin with a basic compound, and disperse the various pigments (high-speed agitator, etc.) A method of preparing an aqueous inkjet ink composition by re-dispersing in water, then adding a bifunctional or higher functional crosslinking agent, heating at 50 to 80 ° C., crosslinking, and adding the remaining materials. Can be mentioned.

<Printing method>
Next, a printing method using the aqueous inkjet ink composition of the present invention will be described.
As the base material for printing of the aqueous inkjet ink composition of the present invention, in addition to plain paper, offset paper and other uncoated paper, art paper, inkjet exclusive paper, inkjet coated paper such as inkjet glossy paper, and Examples include inkjet treat paper.
Then, for example, the water-based inkjet ink composition of the present invention is accommodated in an ink cartridge, the ink cartridge is mounted on a single-pass inkjet recording apparatus, and ejected from the nozzle onto the printing substrate. Thus, inkjet printing can be performed.
By using the water-based inkjet ink composition of the present invention, effects such as no motering can be obtained even when printing on inkjet coated paper and inkjet treat paper.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to these examples. Unless otherwise specified, “%” means “% by mass”, and “part” means “part by mass”.

<Alkali-soluble resin varnish>
Alkali-soluble resin varnish A
25 parts by mass of a copolymer of acrylic acid / lauryl acrylate / styrene = 25/30/45 having a glass transition temperature of 40 ° C., a weight average molecular weight of 30,000 and an acid value of 185 mg KOH / g was added to 4.9 parts by mass of potassium hydroxide. And 70.1 parts by mass of water were dissolved in an alkali-soluble resin varnish A having a solid content of 25%.

Alkali-soluble resin varnish B
25 parts by mass of a copolymer of acrylic acid / stearyl acrylate / styrene = 25/30/45 having a glass transition temperature of 40 ° C., a weight average molecular weight of 30,000, and an acid value of 185 mgKOH / g, 4.9 parts by mass of potassium hydroxide And 70.1 parts by mass of water were dissolved in an alkali-soluble resin varnish B having a solid content of 25%.

Alkali-soluble resin varnish C
25 parts by mass of a copolymer of acrylic acid / lauryl acrylate / styrene = 25/30/45 having a glass transition temperature of 40 ° C., a weight average molecular weight of 30,000, and an acid value of 185 mg KOH / g was added to N, N-dimethylethanolamine 7 It was dissolved in a mixed solution of 8 parts by mass and 67.2 parts by mass of water to obtain an alkali-soluble resin varnish C having a solid content of 25%.

Alkali-soluble resin varnish D
25 parts by mass of a copolymer of acrylic acid / stearyl acrylate / styrene = 25/30/45 having a glass transition temperature of 40 ° C., a weight average molecular weight of 30,000, and an acid value of 185 mg KOH / g was added to N, N-dimethylethanolamine 7 It was dissolved in a mixed solution of 8 parts by mass and 67.2 parts by mass of water to obtain an alkali-soluble resin varnish D having a solid content of 25%.

<Water-based pigment-based ink>
Water-based magenta pigment-based ink A
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish A and mixed to prepare a resin varnish for pigment dispersion. To this varnish, 20 parts by mass of a magenta pigment (trade name Inkjet Magenta E5B02, manufactured by Clariant) was further added, stirred and mixed, and then kneaded with a wet circulation mill to prepare an aqueous magenta pigment base ink A.

Water-based magenta pigment-based ink B
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish B and mixed to prepare a resin varnish for pigment dispersion. To this varnish, 20 parts by mass of a magenta pigment (trade name Inkjet Magenta E5B02, manufactured by Clariant) was further added, stirred and mixed, and then kneaded with a wet circulation mill to prepare an aqueous magenta pigment base ink B.

Water-based magenta pigment-based ink C
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish C and mixed to prepare a resin varnish for pigment dispersion. To this varnish was further added 20 parts by mass of a magenta pigment (trade name Inkjet Magenta E5B02, manufactured by Clariant). After stirring and mixing, the mixture was kneaded with a wet circulation mill to prepare an aqueous magenta pigment base ink C.

Water-based magenta pigment-based ink D
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish D and mixed to prepare a resin varnish for pigment dispersion. To this varnish was further added 20 parts by mass of a magenta pigment (trade name Inkjet Magenta E5B02, manufactured by Clariant), mixed with stirring, and then kneaded with a wet circulation mill to prepare an aqueous magenta pigment base ink D.

Water-based cyan pigment-based ink A
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish A and mixed to prepare a resin varnish for pigment dispersion. To this varnish was further added 20 parts by mass of a cyan pigment (trade name Heliogen Blue L7101F, manufactured by BASF), mixed with stirring, and then kneaded with a wet circulation mill to prepare an aqueous cyan pigment base ink A.

Water-based cyan pigment-based ink B
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish B and mixed to prepare a resin varnish for pigment dispersion. To this varnish was further added 20 parts by mass of a cyan pigment (trade name Heliogen Blue L7101F, manufactured by BASF), mixed with stirring, and then kneaded with a wet circulation mill to prepare an aqueous cyan pigment base ink B.

Water-based cyan pigment-based ink C
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish C and mixed to prepare a resin varnish for pigment dispersion. To this varnish, 20 parts by mass of a cyan pigment (trade name Heliogen Blue L7101F, manufactured by BASF) was further added, stirred and mixed, and then kneaded with a wet circulation mill to prepare an aqueous cyan pigment base ink C.

Water-based cyan pigment-based ink D
48 parts by mass of water was added to 32 parts by mass of the alkali-soluble resin varnish D and mixed to prepare a resin varnish for pigment dispersion. To this varnish, 20 parts by mass of a cyan pigment (trade name Heliogen Blue L7101F, manufactured by BASF) was further added, stirred and mixed, and then kneaded with a wet circulation mill to prepare an aqueous cyan pigment base ink D.

<Aqueous pigment dispersion of pigment coated with alkali-soluble resin>
Aqueous pigment dispersion A of magenta pigment coated with alkali-soluble resin
After diluting the water-based magenta pigment base ink A with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying dispersion device: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion A of magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion B of magenta pigment coated with alkali-soluble resin
After diluting the water-based magenta pigment base ink A with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing device: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion B of a magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion C of magenta pigment coated with alkali-soluble resin
After diluting the water-based magenta pigment base ink B with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion C of a magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion D of magenta pigment coated with alkali-soluble resin
After diluting the water-based magenta pigment base ink B with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing apparatus: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion D of a magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion E of magenta pigment coated with alkali-soluble resin E
After diluting the water-based magenta pigment base ink C with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion E of magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion F of magenta pigment coated with alkali-soluble resin
After diluting the water-based magenta pigment base ink C with water so that the pigment concentration becomes 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing device: Agitated with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion F of a magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion G of magenta pigment coated with alkali-soluble resin
After diluting the aqueous magenta pigment base ink D with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying dispersion device: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion G of magenta pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion H of magenta pigment coated with alkali-soluble resin
After diluting the aqueous magenta pigment base ink D with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing apparatus: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.), An aqueous pigment dispersion H of a magenta pigment coated with an alkali-soluble resin was obtained.

Aqueous pigment dispersion A of cyan pigment coated with alkali-soluble resin
After diluting the water-based cyan pigment base ink A with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion A of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion B of cyan pigment coated with alkali-soluble resin
After diluting the water-based cyan pigment base ink A with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing apparatus: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion B of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion C of cyan pigment coated with alkali-soluble resin
After diluting the aqueous cyan pigment base ink B with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing device: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion C of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion D of cyan pigment coated with alkali-soluble resin
After diluting the aqueous cyan pigment base ink B with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing device: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion D of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion E of cyan pigment coated with alkali-soluble resin
The aqueous cyan pigment base ink C is diluted with water so that the pigment concentration is 5%, and then 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion E of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion F of cyan pigment coated with alkali-soluble resin
The aqueous cyan pigment base ink C is diluted with water so that the pigment concentration is 5%, and then 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing device: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.), An aqueous pigment dispersion F of a cyan pigment coated with an alkali-soluble resin was obtained.

Aqueous pigment dispersion G of cyan pigment coated with alkali-soluble resin
After diluting the water-based cyan pigment base ink D with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. N, N-dimethylethanolamine that neutralizes 65% of the alkali-soluble resin acid value in the resin-coated pigment and water were added to the water-containing cake containing the resin-coated pigment so that the pigment concentration was 12% by mass. Thereafter, the mixture was stirred with a high-pressure emulsifying and dispersing apparatus: Gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion G of a cyan pigment coated with an alkali-soluble resin.

Aqueous pigment dispersion H of cyan pigment coated with alkali-soluble resin
After diluting the water-based cyan pigment base ink D with water so that the pigment concentration is 5%, 5% of cation exchange resin (DOWEX MONOSPHERE (H) 650C, manufactured by Dow Chemical Co., Ltd.) is added to the diluted solution. The mixture was stirred and ion exchanged until the pH was less than 4 to obtain a resin-coated pigment. Thereafter, the ion exchange resin was filtered through a mesh and then suction filtered to obtain a water-containing cake (solid content 25%) containing a resin-coated pigment. After adding sodium hydroxide to neutralize 65% of the alkali-soluble resin acid value in the resin-coated pigment and water so that the pigment concentration becomes 12% by mass to the water-containing cake containing the resin-coated pigment, high-pressure emulsification Dispersing apparatus: Stirring with a gorin homogenizer (manufactured by APV GAULIN INK.) To obtain an aqueous pigment dispersion H of a cyan pigment coated with an alkali-soluble resin.

<Aqueous pigment dispersion of cross-linked resin-coated pigment>
Aqueous pigment dispersion A of cross-linked resin-coated magenta pigment
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600, manufactured by Kyoeisha Chemical Co., Ltd., hereinafter the same) is added to 98.5 parts by mass of the aqueous pigment dispersion A of magenta pigment coated with an alkali-soluble resin. The mixture was heated at 60 ° C. for 24 hours to obtain an aqueous pigment dispersion A of a cross-linked resin-coated magenta pigment.

Aqueous pigment dispersion B of cross-linked resin-coated magenta pigment
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion B of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion B of resin-coated magenta pigment was obtained.

Cross-linked resin-coated magenta pigment aqueous pigment dispersion C
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion C of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion C of resin-coated magenta pigment was obtained.

Cross-linked resin-coated magenta pigment aqueous pigment dispersion D
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion D of magenta pigment coated with an alkali-soluble resin, and the mixture is heated at 60 ° C. for 24 hours. An aqueous pigment dispersion D of a resin-coated magenta pigment was obtained.

Aqueous pigment dispersion E of cross-linked resin-coated magenta pigment
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion E of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion E of resin-coated magenta pigment was obtained.

Aqueous pigment dispersion F of cross-linked resin-coated magenta pigment
1.5 parts by weight of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion F of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion F of resin-coated magenta pigment was obtained.

Aqueous pigment dispersion G of cross-linked resin-coated magenta pigment
1.5 parts by weight of a bifunctional or higher functional crosslinker (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion G of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion G of resin-coated magenta pigment was obtained.

Aqueous pigment dispersion H of cross-linked resin-coated magenta pigment
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion H of magenta pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion H of a resin-coated magenta pigment was obtained.

Cross-linked resin-coated cyan pigment aqueous pigment dispersion A
1.5 parts by weight of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion A of a cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion A of a resin-coated cyan pigment was obtained.

Aqueous pigment dispersion B of cross-linked resin-coated cyan pigment
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion B of cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours to form a crosslinked type. An aqueous pigment dispersion B of a resin-coated cyan pigment was obtained.

Cross-linked resin-coated cyan pigment aqueous pigment dispersion C
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion C of a cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion C of a resin-coated cyan pigment was obtained.

Cross-linked resin-coated cyan pigment aqueous pigment dispersion D
1.5 parts by weight of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion D of cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion D of a resin-coated cyan pigment was obtained.

Cross-linked resin-coated cyan pigment aqueous pigment dispersion E
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion E of cyan pigment coated with an alkali-soluble resin, and the mixture is heated at 60 ° C. for 24 hours. An aqueous pigment dispersion E of a resin-coated cyan pigment was obtained.

Cross-linked resin-coated cyan pigment aqueous pigment dispersion F
1.5 parts by mass of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by mass of an aqueous pigment dispersion F of cyan pigment coated with an alkali-soluble resin, and the mixture is heated at 60 ° C. for 24 hours. An aqueous pigment dispersion F of resin-coated cyan pigment was obtained.

Aqueous pigment dispersion G of cross-linked resin-coated cyan pigment
1.5 parts by weight of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion G of cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours to form a crosslinked type. An aqueous pigment dispersion G of a resin-coated cyan pigment was obtained.

Aqueous pigment dispersion H of cross-linked resin-coated cyan pigment
1.5 parts by weight of a bifunctional or higher functional crosslinking agent (Epolite 1600) is added to 98.5 parts by weight of an aqueous pigment dispersion H of a cyan pigment coated with an alkali-soluble resin, and heated at 60 ° C. for 24 hours. An aqueous pigment dispersion H of a resin-coated cyan pigment was obtained.

<Water-based inkjet ink composition>
Either the water-based magenta or cyan pigment base ink, the water-based pigment dispersion of the magenta or cyan pigment coated with the alkali-soluble resin, or the water-based pigment dispersion of the cross-linked resin-coated cyan pigment, Solvents, surfactants, amino alcohols, and water were mixed with stirring to obtain aqueous inkjet ink compositions of Examples 1 to 23 and Comparative Examples 1 to 6 described in Tables 1 to 5.

<Printing evaluation of water-based inkjet ink composition>
Evaluation was performed by the following evaluation methods, and the results are shown in Tables 1 to 5.
<Storage stability>
The aqueous ink-jet ink compositions of Examples 1 to 23 and Comparative Examples 1 to 6 were filled in a glass bottle and allowed to stand at 60 ° C. for 7 days. Then, the viscosity of the aqueous ink-jet ink composition was measured, and the storage stability was measured. Evaluated.
Evaluation criteria ○: Change rate from initial viscosity is less than 10%
Δ: Change rate from initial viscosity is 10% or more and less than 20% ×: Change rate from initial viscosity is 20% or more

<Discharge stability>
The aqueous ink-jet ink compositions of Examples 1 to 23 and Comparative Examples 1 to 6 are packed in an evaluation printer cartridge equipped with an Epson head and printed on photographic paper <Glossy> (manufactured by EPSON). The ejection stability was evaluated.
Evaluation criteria ○: There is no printing disturbance and can be ejected stably. △: There is some printing disturbance but it can be ejected. ×: There is printing disorder and it cannot be ejected stably.

<Motoring>
The aqueous inkjet ink compositions of Examples 1 to 23 and Comparative Examples 1 to 6 were packed in an evaluation printer cartridge equipped with an Epson head, and printed on a Mitsubishi IJ form (Mitsubishi Paper Co., Ltd.). It was evaluated whether or not the occurrence of motoring was prevented for the secondary color.
Evaluation criteria ○: The print surface has no unevenness and the image quality is good. △: The print surface has some unevenness but is inconspicuous. ×: The entire print surface has noticeable unevenness and the image quality is poor.

According to the results of Examples 1 to 4 which are examples in which the pigment is dispersed together with an alkali-soluble resin and contains amino alcohol, and the results of Comparative Examples 1 and 2 which do not contain amino alcohol, the results of Examples 1 to 4 According to Comparative Examples 1 and 2 that did not contain amino alcohol, although there was some unevenness on the printing surface, it was not noticeable, but it was possible to print more than that, there was a noticeable unevenness on the entire printing surface, The print quality was poor. According to Comparative Example 2 and Comparative Example 4 below, which are particularly poor in discharge stability, it was not possible to evaluate motoring.
In addition, according to the results of Examples 5 to 15 and Comparative Examples 3 and 4 using the resin-coated pigment coated with an alkali-soluble resin, separately from the aqueous pigment dispersion of the resin-coated pigment coated with the alkali-soluble resin. According to Examples 5 to 15 in which it is clear that the amino alcohol is present separately from the resin-coated pigment coated with the alkali-soluble resin in the ink composition by adding a predetermined amount of amino alcohol. The results of Examples 1 to 4 were excellent, and the anti-mottling property was superior to those of Comparative Examples 3 and 4, and the printing surface was somewhat inconspicuous but could not be noticed, or more than that could be printed.
In particular, as in Examples 5, 7, and 9 to 12, when neutralization of the alkali-soluble resin was performed with amino alcohol, occurrence of motoring could be prevented.
Furthermore, according to the results of Examples 16 to 23 and Comparative Examples 5 and 6 in which the alkali-soluble resin was crosslinked with the resin-coated pigment coated with the alkali-soluble resin, the resin-coated pigment coated with the crosslinked alkali-soluble resin According to Examples 16 to 23 in which a predetermined amount of amino alcohol was added by adding a predetermined amount of amino alcohol separately from the aqueous pigment dispersion, the storage stability was obtained in the results of Examples 1 to 4. On the other hand, the anti-mottering property was superior to those of Comparative Examples 5 and 6, and the printing surface was slightly noticeable but not noticeable or more. In particular, as in Examples 16, 18, 20, and 22, when the alkali-soluble resin was neutralized with amino alcohol, it was possible to prevent the occurrence of motoring.

Claims

a. Alkali-soluble resin in which part or all of acid groups are neutralized with a basic compound b. 0.01-10% by mass of free amino alcohol
c. Pigment d. Water-soluble organic solvent e. A water-based inkjet ink composition containing water a to e.
2. The aqueous inkjet ink composition according to claim 1, wherein the basic compound is an amino alcohol.
The aqueous inkjet ink composition according to claim 1 or 2, wherein the pigment is a resin-coated pigment coated with an alkali-soluble resin and / or a crosslinked resin-coated pigment obtained by crosslinking the resin-coated pigment with a bifunctional or higher functional crosslinking agent. object.
The aqueous inkjet ink composition according to any one of claims 1 to 3, wherein the alkali-soluble resin contains a structural unit derived from stearyl (meth) acrylate and / or lauryl (meth) acrylate in the resin. .
The water-based inkjet ink composition according to any one of claims 1 to 4, wherein the content of the water-soluble organic solvent is 10 to 60% by mass in the water-based inkjet ink composition.