Aqueous inkjet ink composition, printed matter, and inkjet printing method

Abstract

An aqueous inkjet ink composition containing a pigment, an alkali-soluble resin, a surfactant, a water-soluble solvent, colloidal silica, and water, wherein the surfactant includes a surfactant (A) having an HLB value of 3 or more but less than 10, and a surfactant (B) having an HLB value of 10 or more but 20 or less, the water-soluble solvent has a boiling point of 170°C or more but 250°C or less at 1 atm, and the proportion of the colloidal silica in the aqueous inkjet ink composition is 0.05% by mass or more but 2% by mass or less. The aqueous inkjet ink composition has good storage stability, mechanical stability, jetting stability, coating film drying properties, and shrinkage resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to an aqueous inkjet ink composition, a printed matter, and an inkjet printing method. BACKGROUND

[0002] The inkjet printing, recording method is a printing, recording method in which an aqueous inkjet ink composition is directly jetted from a very fine nozzle to a printing, recording substrate and adhered to obtain characters or images.

[0003] As such an aqueous inkjet ink composition, for example, a composition containing a pigment, an alkali-soluble resin (pigment dispersing resin), a surfactant, a specific water-soluble solvent, and water, etc. is known (Patent Documents 1 to 4). In these patent documents, an aqueous inkjet ink composition having good storage stability or jetting stability is disclosed. In addition, an aqueous inkjet ink composition containing colloidal silica is known (Patent Documents 5 to 11).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2020-56018

[0007] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2019-1955

[0008] Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2018-104582

[0009] Patent Document 4: Japanese Patent Application Laid-Open (JP-A) No. 2015-137319

[0010] Patent Document 5: Japanese Patent Application Laid-Open (JP-A) No. Hei 9-227812

[0011] Patent Document 6: Japanese Patent Application Laid-Open (JP-A) No. Hei 9-286941

[0012] Patent Document 7: Japanese Patent Application Laid-Open (JP-A) No. Hei 10-152635

[0013] Patent Document 8: Japanese Patent Application Laid-Open (JP-A) No. 2002-29140

[0014] Patent Document 9: Japanese Patent Application Laid-Open (JP-A) No. 2002-20656

[0015] Patent Document 10: Japanese Patent Application Laid-Open (JP-A) No. 2011-62999

[0016] Patent Document 11: Japanese Patent Application Laid-Open (JP-A) No. 2011-63772 SUMMARY

[0017] [Problems to be Solved by the Invention]

[0018] On the other hand, the printing, recording substrate as described above can employ not only non-coated paper such as plain paper or offset paper, but also coated paper or non-absorbing printing media such as polyvinyl chloride sheet. Since the water-based inkjet ink composition is not easily subjected to penetration drying of the water-soluble solvent on such non-absorbing printing media, the drying property of the coating film is decreased, resulting in problems such as a decrease in image quality such as blurring, or a problem of shrinkage of the coated surface.

[0019] Further, the ink composition containing colloidal silica also needs to have mechanical stability so that the colloidal silica does not undergo aggregation during use or during storage.

[0020] The present application was made in view of the actual situation, and aims to provide a water-based inkjet ink composition having good storage stability, mechanical stability, ejection stability, coating film drying property, and shrinkage resistance.

[0021] [Means for Solving the Problems]

[0022] That is, the present application relates to a water-based inkjet ink composition containing a pigment, an alkali-soluble resin, a surfactant, a water-soluble solvent, colloidal silica, and water, and the surfactant contains a surfactant (A) having an HLB value of 3 or more and less than 10, and a surfactant (B) having an HLB value of 10 or more and 20 or less, the water-soluble solvent has a boiling point of 170°C or more and 250°C or less at 1 atm, and the proportion of the colloidal silica in the water-based inkjet ink composition is 0.05 mass% or more and 2 mass% or less.

[0023] Further, the present application relates to a printed matter obtained by printing the water-based inkjet ink composition.

[0024] Further, the present application relates to an inkjet printing method of printing the water-based inkjet ink composition on a non-absorbing printing medium.

[0025] [Effects of the Invention]

[0026] The details of the mechanism of action of the effects of the water-based inkjet ink composition of the present application are not entirely clear, but are presumed as follows. However, the present application is not limited to this mechanism of action for explanation.

[0027] The aqueous inkjet ink composition of the present application contains a pigment, an alkali-soluble resin, a surfactant, a water-soluble solvent, colloidal silica, and water, the surfactant contains a surfactant (A) having an HLB value of 3 or more and less than 10, and a surfactant (B) having an HLB value of 10 or more and 20 or less, the water-soluble solvent has a boiling point of 170°C or more and 250°C or less at 1 atm, and in the aqueous inkjet ink composition, the proportion of the colloidal silica is 0.05 mass% or more and 1 mass% or less. By adding the surfactant (A) having a low HLB value, the surface tension of the ink is lowered, and the entrainment of air bubbles from the nozzle face is suppressed, so the ejection stability of the aqueous inkjet ink composition of the present application becomes good. Further, since the surfactant (B) having a high HLB value has an effect of compatibilizing the surfactant (A) with water, the storage stability, the ejection stability, and the coating film drying property of the aqueous inkjet ink composition of the present application become good. Further, by containing a specific amount of colloidal silica, the adsorptivity on the surface of a substrate is improved, and the coagulation of droplets is suppressed, so the shrinkage resistance becomes good. Further, by containing colloidal silica in an amount of less than a specific amount, the mechanical stability also becomes good. DETAILED DESCRIPTION

[0028] The aqueous inkjet ink composition of the present application contains a pigment, an alkali-soluble resin, a surfactant, a water-soluble solvent, colloidal silica, and water.

[0029] < Pigment >

[0030] The pigment of the present application can be used without particular limitation, using an organic pigment or an inorganic pigment used in an inkjet ink composition. As the organic pigment, for example, there can be mentioned dye lake pigments, azo-based pigments, benzimidazolone-based pigments, phthalocyanine-based pigments, quinacridone-based pigments, anthraquinone-based pigments, dioxazine-based pigments, indigo-based pigments, thioindigo-based pigments, perylene-based pigments, perinone-based pigments, diketopyrrolopyrrole-based pigments, isoindolinone-based pigments, nitro-based pigments, nitroso-based pigments, flavanthrone-based pigments, quinophthalone-based pigments, pyranthrone-based pigments, indanthrone-based pigments, and the like. Further, as the inorganic pigment, for example, there can be mentioned carbon black, titanium oxide, zinc white, red iron oxide, graphite, black iron oxide, chromium oxide green, aluminum hydroxide, and the like. The pigments can also be subjected to surface treatment with a well-known surface treatment agent. The pigments can be used alone, or in combination of two or more.

[0031] As specific examples of each typical color tone of the pigment, the following pigments can be mentioned.

[0032] As yellow pigments, for example, C.I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213, etc. can be exemplified.

[0033] As magenta pigments, for example, C.I. Pigment Red 5, 7, 12, 22, 38, 48: 1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I. Pigment Violet 19, etc. can be exemplified.

[0034] As cyan pigments, for example, C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, 60, etc. can be exemplified.

[0035] As black pigments, for example, carbon black (C.I. Pigment Black 7), etc. can be exemplified.

[0036] As white pigments, for example, titanium oxide, aluminum oxide, etc. can be exemplified, and various materials such as alumina, silica, etc. can be surface-treated.

[0037] <Alkali-soluble resin>

[0038] The alkali-soluble resin of the present application is not particularly limited as long as it is an alkali-soluble resin that can be used for pigment dispersion purposes or adhesives of ordinary inks or paints, and can be dissolved in an aqueous medium in the presence of an alkali compound, and is preferably a resin containing one or two or more anionic groups such as carboxyl groups, sulfonic acid groups, phosphonic acid groups (-P(=0)(OH2)), etc.

[0039] The alkali-soluble resin preferably further has a hydrophobic moiety in its molecule, and is mainly used to improve the adsorptivity to pigments. As the hydrophobic moiety introduced into the molecule, for example, hydrophobic groups such as long-chain alkyl groups, alicyclic groups, aromatic cyclic hydrocarbon groups, etc. can be exemplified.

[0040] The acid value of the alkali-soluble resin is preferably 40 mgKOH / g or more, more preferably 70 mgKOH / g or more, from the viewpoint of improving the solubility in an aqueous medium. In addition, the acid value of the alkali-soluble resin is preferably 300 mgKOH / g or less, more preferably 250 mgKOH / g or less, from the viewpoint of improving the water resistance of the printed matter. In addition, the acid value is a theoretical acid value obtained by calculating the number of mg of potassium hydroxide required to neutralize 1 g of the alkali-soluble resin theoretically, based on the composition of the monomers used for the synthesis of the alkali-soluble resin.

[0041] The glass transition temperature of the alkali-soluble resin is preferably 0°C or more, more preferably 10°C or more, from the viewpoint of improving the blocking resistance of the printed matter. The glass transition temperature of the alkali-soluble resin is preferably 100°C or less, more preferably 80°C or less, from the viewpoint of improving the folding endurance of the printed matter.

[0042] In the case where the alkali-soluble resin is an acrylic copolymer resin, the glass transition temperature of the alkali-soluble resin is a theoretical glass transition temperature obtained by the following wood formula.

[0043] Wood formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 +... + Wx / Tgx

[0044] [In the formula, Tg1 to Tgx represent the glass transition temperatures of the respective homopolymers of monomers 1, 2, 3,... x constituting the alkali-soluble resin, W1 to Wx represent the polymerization ratios of the respective monomers 1, 2, 3,... x, and Tg represents the theoretical glass transition temperature. In the wood formula, the glass transition temperature is an absolute temperature.]

[0045] In the case where the alkali-soluble resin is a resin other than the acrylic copolymer resin, the glass transition temperature of the alkali-soluble resin is a theoretical glass transition temperature obtained by thermal analysis. As the method of thermal analysis, the glass transition temperature can be measured using, for example, a Pyris 1 DSC manufactured by PerkinElmer under conditions of a temperature increase rate of 20°C / min and a nitrogen flow rate of 20 ml / min in accordance with JIS K7121 (Method for measuring transition temperature of plastics).

[0046] The weight average molecular weight of the alkali-soluble resin is preferably 5,000 or more, more preferably 10,000 or more, from the viewpoint of improving the water resistance of the printed matter. The weight average molecular weight of the alkali-soluble resin is preferably 100,000 or less, more preferably 50,000 or less, from the viewpoint of improving the solubility in an aqueous medium.

[0047] The weight average molecular weight can be measured by a gel permeation chromatography (GPC) method. As an example, a Water 2690 (manufactured by Waters Corporation) can be used as a GPC device, a PLgel, 5μ, MIXED-D (manufactured by Polymer Laboratories) can be used as a column, tetrahydrofuran can be used as a developing solvent, a chromatography can be performed at a column temperature of 25°C, a flow rate of 1 mL / min, an RI detector, a sample injection concentration of 10 mg / mL, and an injection amount of 100 μL, and a weight average molecular weight in terms of polystyrene can be calculated as the weight average molecular weight.

[0048] As the alkali-soluble resin, for example, an acrylic copolymer resin, a maleic acid copolymer resin, a polyester resin obtained by a polycondensation reaction, a polyurethane resin, and the like can be exemplified. As to the materials used for synthesizing such alkali-soluble resins, for example, those disclosed in Japanese Patent Application Publication No. 2000-94825 can be used, and an acrylic copolymer resin, a maleic acid copolymer resin, a polyester resin, a polyurethane resin, and the like obtained from the materials described in the publication can be used. Further, a resin obtained from other materials than these materials can also be used. The alkali-soluble resin can be used alone or in combination of two or more.

[0049] As the acrylic copolymer resin, for example, an acrylic copolymer resin obtained by polymerizing a mixture of other monomers capable of copolymerizing with the anionic group-containing monomer in the presence of a general radical generator (for example, benzoyl peroxide, t-butyl peroxybenzoate, azobisisobutyronitrile, and the like) in a solvent can be used.

[0050] As the anionic group-containing monomer, for example, a monomer having at least one anionic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphonic acid group can be exemplified, and a monomer having a carboxyl group is particularly preferable.

[0051] As the monomer having a carboxyl group, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, maleic anhydride, fumaric anhydride, maleic acid half ester, and the like can be exemplified. Further, as the monomer having a sulfonic acid group, for example, sulfoethyl methacrylate and the like can be exemplified. Further, as the monomer having a phosphonic acid group, for example, phosphonoethyl methacrylate and the like can be exemplified.

[0052] As the other monomer capable of copolymerizing with the anionic group-containing monomer, a monomer containing a hydrophobic group is preferable from the viewpoint of improving the adsorptivity to pigments.

[0053] As the monomer containing a hydrophobic group, for example, mention can be made of: a monomer having a long-chain alkyl group, such as alkyl esters of a radical-polymerizable unsaturated carboxylic acid having a carbon number of 8 or more, such as (meth)acrylic acid (e.g., 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxy stearyl (meth)acrylate, etc.), alkyl vinyl ethers having a carbon number of 8 or more (e.g., dodecyl vinyl ether, etc.), vinyl esters of a fatty acid having a carbon number of 8 or more (e.g., 2-ethylhexanoic acid vinyl ester, lauric acid vinyl ester, stearic acid vinyl ester, etc.); a monomer having an alicyclic hydrocarbon group, such as cyclohexyl (meth)acrylate, etc.; a monomer having an aromatic hydrocarbon group, such as benzyl (meth)acrylate, styrene, α-methyl styrene, vinyltoluene, a styrene-based monomer, etc. The monomer containing a hydrophobic group can be used alone or in combination of two or more.

[0054] As the other monomer copolymerizable with the monomer containing an anionic group, from the viewpoint of inhibiting the aggregation of the alkali-soluble resin in an aqueous medium, a monomer containing a hydrophilic group can be included.

[0055] As the monomer containing a hydrophilic group, for example, mention can be made of: a monomer having a (poly)oxyalkylene chain, such as an ester of a mono-terminal alkyl-terminated (poly)alkylene glycol with a radical-polymerizable unsaturated carboxylic acid such as (meth)acrylic acid, or an oxirane adduct and / or an oxetane adduct of a radical-polymerizable unsaturated carboxylic acid such as (meth)acrylic acid, etc.; a monomer containing a basic group, such as 1-vinyl-2-pyrrolidone, 1-vinyl-3-pyrrolidone, a vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine, a vinylpyridine, 1-vinylimidazole, 1-vinyl-2-methylimidazole, a vinylimidazole, 3-vinylpiperidine, N-methyl-3-vinylpiperidine, a vinylpiperidine, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-methoxy (meth)acrylamide, N-ethoxy (meth)acrylamide, N-dimethylacrylamide, N-propylacrylamide, a nitrogen-containing derivative of (meth)acrylic acid, etc.; a monomer having a hydroxyl group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, a hydroxyalkyl ester of (meth)acrylic acid, etc.; a monomer having an epoxy group, such as glycidyl (meth)acrylate, etc. The monomer containing a hydrophilic group can be used alone or in combination of two or more.

[0056] As the other monomer copolymerizable in addition to the monomer containing the hydrophobic group and the monomer containing the hydrophilic group, for example, there can be mentioned alkyl esters of (meth)acrylic acid having a carbon number of 8 or less such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, and the like. The other monomer copolymerizable in addition to the monomer containing the hydrophobic group and the monomer containing the hydrophilic group can be used alone or in combination of two or more.

[0057] <Surfactant>

[0058] The surfactant of the present application contains a surfactant (A) having an HLB value of 3 or more and less than 10, and a surfactant (B) having an HLB value of 10 or more and 20 or less. Here, the HLB value means an index indicating the degree of hydrophilicity and lipophilicity of a surfactant calculated by Griffin's method, and the smaller the HLB value, the higher the lipophilicity, and the larger the HLB value, the higher the hydrophilicity. The surfactant (A) and the surfactant (B) can be used alone or in combination of two or more.

[0059] The surfactant (A) and the surfactant (B) are not particularly limited as long as the respective HLB values are satisfied, and can be used as the well-known surfactants used in aqueous inkjet inks, for example, nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants. As specific examples of the surfactants, for example, there can be mentioned silicone-based surfactants, fluorine-based surfactants, acetylene-based surfactants, and the like. Among them, from the viewpoint of improving the ejection stability and the shrinkage resistance, acetylene-based surfactants are preferred.

[0060] As the surfactant (A), for example, there can be mentioned surfactants having trade names of "Surfynol 104E", "Surfynol 104H", "Surfynol 104A", "Surfynol 104BC", "Surfynol 104DPM", "Surfynol 104PA", "Surfynol 104PG-50", "Surfynol 420", "Surfynol 440", "Olfine E1004" (all manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

[0061] As the surfactant (B), for example, there can be mentioned surfactants of trade names "Surfynol 465", "Surfynol 485", "Olfine E1010", "Olfine E1020" (all manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

[0062] <Water-soluble solvent>

[0063] The water-soluble solvent of the present application has a boiling point of 170°C or higher and 250°C or lower at 1 atm.

[0064] The water-soluble solvent is not particularly limited as long as it has a boiling point of 170°C or higher and 250°C or lower at 1 atm, and for example, there can be mentioned monoalcohols, polyhydric alcohols, lower alkyl ethers of polyhydric alcohols, nitrogen-containing compounds, and the like.

[0065] As the water-soluble solvent, for example, there can be mentioned 1-octanol (boiling point 195°C), 2-ethylhexanol (boiling point 184°C), propylene glycol (boiling point 188°C), 1,2-butanediol (boiling point 197°C), ethylene glycol (boiling point 197°C), 3-methoxy-3-methyl-l-butanol (boiling point 174°C), diethylene glycol (boiling point 245°C), dipropylene glycol monomethyl ether (boiling point 188°C), dipropylene glycol dimethyl ether (boiling point 175°C), diethylene glycol monomethyl ether (boiling point 194°C), diethylene glycol monoethyl ether (boiling point 196°C), diethylene glycol monobutyl ether (boiling point 231°C), N-methylpyrrolidone (boiling point 202°C), 2-pyrrolidone (boiling point 245°C), and the like.

[0066] The water-based inkjet ink composition of the present application can also contain a solvent (other solvent) for a water-based inkjet ink composition other than the water-soluble solvent.

[0067] <Colloidal silica>

[0068] The colloidal silica of the present application is silica in which silica particles represented by the chemical formula SiO2 are dispersed in a medium to form a colloid. As the medium, for example, there can be mentioned water, methanol, ethanol, isopropanol, n-butanol, xylene, dimethylformamide, and the like. Further, in the colloidal silica, the surface of the silica particles can be modified with a surface treatment agent such as a silane compound. The colloidal silica can be used alone or in combination of two or more.

[0069] The average particle diameter of the colloidal silica is preferably 3 to 100 nm, more preferably 5 to 30 nm. The average particle diameter is the average primary particle diameter, which is represented by the median particle diameter (D50) of the volume-based particle size distribution measured by a dynamic light scattering method. Further, as the shape of the colloidal silica, particle shape, chain shape, pearl chain shape, and the like can be exemplified.

[0070] As the commercially available product of the colloidal silica, for example, colloidal silica of trade names "SNOWTEX XS", "SNOWTEX S", "SNOWTEX 30", "SNOWTEX 50T", "SNOWTEX 30L", "SNOWTEX YL", "SNOWTEX ZL", "SNOWTEX MP1040", "SNOWTEX UP", "SNOWTEX PS-S", "SNOWTEX PS-M", "SNOWTEX OXS", "SNOWTEX OS", "SNOWTEX O", "SNOWTEX O-40", "SNOWTEX OL", "SNOWTEX OYL", "SNOWTEX OUP", "SNOWTEX PS-SO", "SNOWTEX PS-MO", "SNOWTEX NXS", "SNOWTEX NS", "SNOWTEX N", "SNOWTEX N-40", "SNOWTEX CXS", "SNOWTEX C", "SNOWTEX CM", "SNOWTEX AK", "SNOWTEX AK-L", "SNOWTEX AK-Y", "ORGANOSILICASOL EG-ST", "ORGANOSILICASOL PMG-ST", "ORGANOSILICASOL IPα-ST" (all manufactured by Nissan Chemical Industries, Ltd.), "Levasil CC151", "Levasil CC301", "Levasil CC401", "Levasil CC503" (all manufactured by Nalge Nunc International Corp.), and the like can be exemplified.

[0071] <Water>

[0072] The water of the present application includes water contained in the pigment dispersion liquid described later as an aqueous medium, and water added for adjusting the concentration of the aqueous inkjet ink composition of the present application, and the like. As the water, for example, ion-exchanged water, pure water, distilled water, industrial water, and the like can be exemplified. The water can be used alone, or two or more kinds can be used in combination.

[0073] Hereinafter, the proportions of each component in the aqueous inkjet ink composition of the present application are described.

[0074] The proportion of the pigment in the aqueous inkjet ink composition of the present application is preferably 1% by mass or more, more preferably 2% by mass or more, from the viewpoint of improving the print density of a printed matter, and is preferably 10% by mass or less, more preferably 8% by mass or less, from the viewpoint of improving the jetting stability. However, in the case where the pigment is a white pigment, the proportion of the white pigment in the aqueous inkjet ink composition of the present application is preferably 4% by mass or more, more preferably 8% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less.

[0075] The content of the alkali-soluble resin is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, relative to 100 parts by mass of the pigment, from the viewpoint of improving the dispersibility of the pigment. The content of the alkali-soluble resin is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further preferably 60 parts by mass or less, relative to 100 parts by mass of the pigment, from the viewpoint of reducing the viscosity of the aqueous inkjet composition.

[0076] The proportion of the surfactant (A) in the aqueous inkjet ink composition of the present application is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, further preferably 0.4% by mass or more, from the viewpoint of improving the jetting stability, and is preferably 3% by mass or less, more preferably 2% by mass or less, from the viewpoint of improving the storage stability.

[0077] The proportion of the surfactant (B) in the aqueous inkjet ink composition of the present application is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, further preferably 0.4% by mass or more, from the viewpoint of improving the jetting stability and the storage stability, and is preferably 3% by mass or less, more preferably 2% by mass or less, from the viewpoint of improving the storage stability.

[0078] The proportion of the water-soluble solvent in the aqueous inkjet ink composition of the present application is preferably 15% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving the jetting stability, and is preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoint of improving the drying property of a coating film.

[0079] The proportion of the colloidal silica in the aqueous inkjet ink composition of the present application is 0.05 mass% or more and 2 mass% or less. From the viewpoint of improving the storage stability, the ejection stability, and the shrinkage resistance, the proportion of the colloidal silica in the aqueous inkjet ink composition of the present application is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and from the viewpoint of improving the storage stability, the mechanical stability, the ejection stability, and the shrinkage resistance, it is preferably 1.5 mass% or less, more preferably 1.0 mass% or less, and further preferably 0.8 mass% or less.

[0080] From the viewpoint of improving the drying property of the coating film, the proportion of the water (including the water contained in each component) in the aqueous inkjet ink composition of the present application is preferably 40 mass% or more, more preferably 50 mass% or more, and from the viewpoint of improving the ejection stability, it is preferably 70 mass% or less, more preferably 60 mass% or less.

[0081] <Resin emulsion>

[0082] From the viewpoint of improving the drying property and the shrinkage resistance of the coating film, the aqueous inkjet ink composition of the present application preferably contains a resin emulsion. The resin emulsion can employ a well-known resin emulsion used in an aqueous inkjet ink composition, and examples thereof include an acrylic resin emulsion, a styrene-acrylic resin emulsion, a polyester resin emulsion, a polyurethane resin emulsion, a polyvinyl acetate resin emulsion, a polyvinyl chloride resin emulsion, a polybutadiene resin emulsion, a polyolefin resin emulsion, and the like. From the viewpoint of improving the drying property of the coating film of a printed matter or the adhesiveness to a substrate, the glass transition temperature of the resin of the resin emulsion is preferably 20°C or lower. In addition, the glass transition temperature is referred to the catalog value of the manufacturer, but in the case where the catalog value cannot be obtained, the glass transition temperature is calculated by differential scanning calorimetry (DSC), and is usually calculated from the midpoint of the temperature range in which the glass transition occurs. The resin emulsion can be used alone or in combination of two or more.

[0083] From the viewpoint of improving the print quality and the abrasion resistance, the proportion of the (resin) solid component of the resin emulsion in the aqueous inkjet ink composition is preferably 1 mass% or more, and preferably 2 mass% or more, and from the viewpoint of improving the print quality and the storage stability, it is preferably 10 mass% or less, more preferably 5 mass% or less.

[0084] <Alkaline compound>

[0085] An alkaline compound is preferably contained in the aqueous inkjet ink composition of the present application from the viewpoint of dissolving the alkali-soluble resin. As the alkaline compound, for example, inorganic alkaline compounds such as sodium hydroxide, potassium hydroxide, and the like; organic alkaline compounds such as ammonia, methylamine, ethylamine, monoethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, and the like; and the like can be exemplified. The alkaline compound can be used alone or in combination of two or more.

[0086] The proportion of the alkaline compound in the aqueous inkjet ink composition of the present application can be an amount that enables the alkali-soluble resin to be dissolved in the medium, and in general, from the viewpoint of improving the dispersion stability of the alkali-soluble resin, it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and from the viewpoint of improving the water resistance of the printed matter, it is preferably 1% by mass or less, more preferably 0.5% by mass or less.

[0087] In the aqueous inkjet ink composition of the present application, a well-known resin, a resin emulsion, a wax emulsion, a pigment dispersant, a mildew preventive, a rust preventive, an adhesion promoter, an antioxidant, an ultraviolet absorber, a storage property improver, an antifoaming agent, a pH adjustor, and the like can be further added as an additive according to the purpose.

[0088] <Method for producing the aqueous inkjet ink composition>

[0089] The method for producing (manufacturing) the aqueous inkjet ink composition of the present application is not particularly limited, and for example, a method in which the components are sequentially or simultaneously added and mixed can be exemplified, such as: (1) a method in which the alkali-soluble resin is dissolved in water in the presence of the alkaline compound, the aqueous resin varnish, the pigment, and the pigment dispersant and the like, if necessary, obtained thereby are mixed, and a pigment dispersion liquid (ink base) is produced using various dispersing machines such as a ball mill, an attritor, a roll mill, a sand mill, a stirring mill, and the like, and the remaining materials are further added to produce the aqueous inkjet ink composition; and (2) a method in which the pigment is dispersed using the method, a resin-coated pigment in which the alkali-soluble resin is precipitated onto the surface of the pigment is obtained by a method of acid deposition or an ion exchange means described in Japanese Re-publication No. WO2005 / 116147, and the like, and the obtained resin-coated pigment is neutralized using the alkaline compound, and the pigment is again dispersed in water using various dispersing machines (high-speed stirring device, and the like), and the remaining materials are further added to produce the aqueous inkjet ink composition.

[0090] The aqueous inkjet ink composition of the present application has an initial viscosity after production in the range of 2.0 to 15.0 mPa-s, preferably 3.0 to 12.0 mPa-s. The viscosity can be measured, for example, using an E-type viscometer (trade name "RE100L-type viscometer", manufactured by Tokimec, Inc.).

[0091] <Printed Matter>

[0092] The printed matter of the present application is obtained by printing the aqueous inkjet ink composition. Specifically, the aqueous inkjet ink composition is applied (printed) on a substrate using an inkjet printer.

[0093] As the substrate, for example, coated paper such as art paper, inkjet special paper, inkjet glossy paper, and the like; non-absorbing printing media such as plastic-based substrates such as polypropylene film or polyvinyl chloride sheet, and the like; uncoated paper such as plain paper, offset paper, and the like; fabric such as cotton cloth, and the like can be exemplified. In particular, since the aqueous inkjet ink composition of the present application is excellent in shrink resistance, it is suitable for plastic-based substrates among non-absorbing printing media.

[0094] <Inkjet Printing Method>

[0095] The inkjet printing method of the present application can be appropriately applied with conditions well known in the art, and for example, a method in which the aqueous inkjet ink composition is loaded in an ink cartridge, and the ink cartridge is installed in an inkjet recording device such as a single-pass inkjet device, and the aqueous inkjet ink composition is ejected from a nozzle toward a substrate to perform inkjet printing can be exemplified.

[0096] Examples

[0097] Hereinafter, the present application will be described based on examples, but the present application is not limited only to these examples.

[0098] <Production Example 1>

[0099] <Production of Pigment Dispersion Liquid (Based on Black Ink)>

[0100] An alkali-soluble resin (acrylic acid / n-butyl acrylate / benzyl methacrylate / styrene copolymer, weight average molecular weight 30,000, acid value 185 mgKOH / g, glass transition temperature 40°C) 20 parts by mass was dissolved in a mixed solution of potassium hydroxide 2.5 parts by mass and water 77.5 parts by mass to obtain an aqueous resin varnish having a solid content of 20% by mass of the alkali-soluble resin. Next, a resin varnish for pigment dispersion was prepared by adding and mixing water 64.3 parts by mass to the aqueous resin varnish 23.7 parts by mass. After further adding and stirring-mixing carbon black (trade name "Printex 90", manufactured by DKS Co., Ltd.) 12 parts by mass as a pigment in the resin varnish for pigment dispersion, a wet-type circulation mill was used for grinding to thereby produce a black pigment dispersion liquid (based on black ink) of Production Example 1.

[0101] <Production Examples 2 to 4>

[0102] <Production of Pigment Dispersion Liquids (based on yellow, magenta, and cyan inks)>

[0103] Instead of carbon black (trade name "Printex 90", manufactured by DKS Co., Ltd.) described in Production Example 1, a yellow pigment (trade name "Novoperm Yellow 4G01", manufactured by Clariant Co., Ltd.), a magenta pigment (trade name "INK JET Magenta E5B02", manufactured by Clariant Co., Ltd.), or a cyan pigment (trade name "Heliogen Blue L7101F", manufactured by BASF Co., Ltd.) was used, and otherwise the same method as Production Example 1 was performed to thereby produce a yellow pigment dispersion liquid (based on yellow ink) of Production Example 2, a magenta pigment dispersion liquid (based on magenta ink) of Production Example 3, and a cyan pigment dispersion liquid (based on cyan ink) of Production Example 4.

[0104] <Production Example 5>

[0105] <Production of Pigment Dispersion Liquid (based on white ink)>

[0106] A resin varnish for pigment dispersion was prepared by adding and mixing water 20.0 parts by mass to the aqueous resin varnish 40.0 parts by mass described in Production Example 1. After further adding and stirring-mixing titanium oxide (trade name "R-960", manufactured by DuPont Co.) 40 parts by mass as a pigment in the resin varnish for pigment dispersion, a wet-type circulation mill was used for grinding to thereby produce a white pigment dispersion liquid (based on white ink) of Production Example 5.

[0107] <Example 1>

[0108] <Production of Aqueous Inkjet Ink Composition>

[0109] The black pigment dispersion liquid (as a base of black ink), propylene glycol as a water-soluble solvent, ethynyl surfactant (trade name "Olfine E1004", solid content (effective ingredient) 100%, HLB value 8, manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant (A), ethynyl surfactant (trade name "Olfine E1010", solid content (effective ingredient) 100%, HLB value 13, manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant (B), colloidal silica (trade name "SNOWTEX 30", solid content 30%, particle diameter 12 nm, Na + Stable basic sol, manufactured by Nissan Chemical Industries, Ltd.), styrene-acrylic resin emulsion (trade name "Neocryl A-1092", solid content 48.5%, glass transition temperature 6°C, manufactured by DSM) as a resin emulsion, and water were mixed by stirring to achieve the mass proportions of Table 1, thereby producing the water-based inkjet ink composition of Example 1.

[0110] <Examples 2 to 26 and Comparative Examples 1 to 9>

[0111] <Manufacture of Water-Based Inkjet Ink Composition>

[0112] In each of the examples and comparative examples, the raw materials used and their amounts were changed as shown in Tables 1 to 4, and otherwise, the water-based inkjet ink composition of each of the examples and comparative examples was manufactured by the same method as in Example 1.

[0113] <Evaluation of Water-Based Inkjet Ink Composition>

[0114] The evaluation was performed by the following method, and the results of the evaluation are shown in Tables 1 to 4. In addition, in the following evaluation, the ink composition was evaluated as not passing if there was an X.

[0115] <Storage Stability>

[0116] Each of the water-based inkjet ink compositions produced above was taken in a glass bottle, and the viscosity (mPa-s) at 25°C was measured using a viscometer (manufactured by Tokimec, Inc., "RE100L type"). Thereafter, the glass bottle was tightly capped and stored at 60°C for one month, and the viscosity after storage (at 25°C) was measured using the viscometer. The storage stability was evaluated based on the rate of change in viscosity (at 60°C, (viscosity after one month - viscosity before storage) / viscosity before storage).

[0117] [Criteria for Evaluation of Storage Stability]

[0118] O: The rate of change in viscosity was not 5%.

[0119] Δ: Viscosity change rate is 5% or more and less than 10%.

[0120] X: Viscosity change rate is 10% or more.

[0121] <Mechanical stability>

[0122] Each of the aqueous inkjet ink compositions prepared above was taken in a polyethylene container, and circulated for 500 cycles using a diaphragm pump (manufactured by KNF, NF60) in a water bath at 25°C. After the circulated ink was filtered using a 150-mesh polyester screen, the residue was evaluated visually.

[0123] [Criteria for evaluation of mechanical stability]

[0124] O: No residue.

[0125] Δ: A little residue was visible.

[0126] X: A large amount of residue was visible.

[0127] <Discharge stability>

[0128] The aqueous inkjet ink compositions prepared above were loaded into a cassette of an inkjet printer ("PX105", manufactured by Epson Corporation), and printing was performed on a photo paper ("GL-101A450", manufactured by Canon Inc.) to evaluate the discharge stability.

[0129] [Criteria for evaluation of discharge stability]

[0130] O: Almost no printing distortion, and stable discharge was possible.

[0131] Δ: A little printing distortion was present, but discharge was possible.

[0132] X: Printing distortion was present, and stable discharge was not possible.

[0133] <Drying property of coating film>

[0134] The aqueous inkjet ink compositions prepared above were loaded into a cassette of an inkjet printer ("PX105", manufactured by Epson Corporation), and printing was performed on an OK Topcoat paper (manufactured by Oji Paper Co., Ltd.). After the printed matter was left to stand at 80°C for 3 minutes to dry the ink, the printed portion was wiped with a cotton swab, and the drying property of the coating film was evaluated.

[0135] [Criteria for evaluation of drying property of coating film]

[0136] O: No ink adhered to the cotton swab.

[0137] Δ: A little ink adhered to the cotton swab.

[0138] X: A large amount of ink adhered to the swab.

[0139] <Shrinkage resistance>

[0140] The water-based inkjet ink composition prepared above was coated on an OPP film (P2161, 25 μm, manufactured by Toyobo Co., Ltd.) using a 0.15 mm bar coater, and the shrinkage resistance was evaluated by visual observation.

[0141] [Criteria for evaluation of shrinkage resistance]

[0142] O: No shrinkage, and uniform coating was possible.

[0143] Δ: Slight shrinkage, but coating was possible.

[0144] X: Shrinkage occurred, and uniform coating was obviously impossible.

[0145]

[0146]

[0147]

[0148]

[0149] The boiling point of propylene glycol is 188°C;

[0150] The boiling point of dipropylene glycol dimethyl ether is 175°C;

[0151] The boiling point of diethylene glycol monobutyl ether is 231°C;

[0152] The boiling point of ethylene glycol monomethyl ether is 124°C;

[0153] The boiling point of tripropylene glycol monobutyl ether is 274°C.

[0154] Further, the following components are shown in Tables 1 to 4:

[0155] Olfine E1004 is an acetylene-based surfactant (solid content (active ingredient): 100%, HLB: 8, manufactured by Nissin Chemical Industry Co., Ltd.);

[0156] Surfynol 104E is an acetylene-based surfactant (solid content (active ingredient): 50%, HLB: 4, manufactured by Nissin Chemical Industry Co., Ltd.);

[0157] Olfine E1010 is an acetylene-based surfactant (solid content (active ingredient): 100%, HLB: 13, manufactured by Nissin Chemical Industry Co., Ltd.);

[0158] Surfynol 485 is an acetylene-based surfactant (solid content (active ingredient): 100%, HLB: 17, manufactured by Nissin Chemical Industry Co., Ltd.);

[0159] SNOWTEX 30 is colloidal silica (solid content: 30%, particle diameter: 12 nm, Na + stabilized basic sol, manufactured by Showa Denko K.K.);

[0160] SNOWTEX XS is colloidal silica (solid content: 20%, particle diameter: 5 nm, Na + stabilized basic sol, manufactured by Showa Denko K.K.);

[0161] SNOWTEX O is colloidal silica (solid content: 20%, particle diameter: 12 nm, acid sol, manufactured by Showa Denko K.K.);

[0162] SNOWTEX N is colloidal silica (solid content: 20%, particle diameter: 12 nm, NH4 + stabilized basic sol, manufactured by Showa Denko K.K.);

[0163] SNOWTEX C is colloidal silica (solid content: 20%, particle diameter: 12 nm, neutral region stabilized sol, manufactured by Showa Denko K.K.);

[0164] Levasil CC151 is colloidal silica (solid content: 15%, particle diameter: 5 nm, silane-modified colloidal silica, manufactured by Wacker Chemie AG);

[0165] Levasil CC301 is colloidal silica (solid content: 28%, particle diameter: 7 nm, silane-modified colloidal silica, manufactured by Wacker Chemie AG);

[0166] Levasil CC401 is colloidal silica (solid content: 37%, particle diameter: 12 nm, silane-modified colloidal silica, manufactured by Wacker Chemie AG);

[0167] Levasil CC503 is colloidal silica (solid content: 50%, particle diameter: 34 nm, silane-modified colloidal silica, manufactured by Wacker Chemie AG);

[0168] Neocryl A-1092 (solid content: 48.5%, styrene-acrylic emulsion, manufactured by DSM, glass transition temperature: 6°C).

Claims

1. A water-based inkjet ink composition comprising pigment, alkali-soluble resin, surfactant, water-soluble solvent, colloidal silica, and water, characterized in that: The surfactants include surfactants (A) with an HLB value of 3 or higher but less than 10, and surfactants (B) with an HLB value of 10 or higher but less than 20. The boiling point of the water-soluble solvent is between 170°C and 250°C at 1 atmosphere. In the water-based inkjet ink composition, the proportion of the water-soluble solvent is more than 15% by mass and less than 60% by mass. In the water-based inkjet ink composition, the proportion of colloidal silica is more than 0.05% by mass and less than 2% by mass.

2. The water-based inkjet ink composition according to claim 1, characterized in that, The water-soluble solvent is one or more solvents selected from the group consisting of monools, polyols, lower alkyl ethers of polyols, and nitrogen-containing compounds.

3. The water-based inkjet ink composition according to claim 1 or 2, characterized in that... It contains resin emulsion.

4. A printed material, characterized in that, It is obtained by printing an aqueous inkjet ink composition according to any one of claims 1 to 3.

5. An inkjet printing method, characterized in that, The water-based inkjet ink composition according to any one of claims 1 to 3 is used to print on a non-absorbent printing medium.

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