Precoat agent, ink set for ink-jet recording, and laminate

Abstract

To provide a precoat agent which can suppress solid filling and bleeding and improve printing image quality without using a polyvalent metal salt when an ink composition for inkjet recording is printed, can suppress strike-through of the ink composition for inkjet recording, and can suppress peeling of an overcoat layer and deterioration of hardness in a post process (formation of overcoat layer).SOLUTION: A precoat agent is used for forming a precoat layer for receiving an ink composition for inkjet recording, contains inorganic particles, an amine salt of an organic acid, resin emulsion and water, where a particle diameter of the inorganic particles is 1-10 μm, and the precoat agent does not contain a polyvalent metal salt.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a precoat agent, an ink set for ink-jet recording, and a laminate. [Background technology]

[0002] 2. Description of the Related Art There is known an image forming method in which a precoat agent (pretreatment liquid) is applied or discharged onto the surface of a substrate, and then an ink composition for inkjet recording is discharged to aggregate pigments on the substrate, thereby achieving high image quality.

[0003] For example, Patent Document 1 discloses an image forming method including a pretreatment step of applying a pretreatment liquid onto a recording medium having a coating layer on a support, an image forming step of applying an inkjet ink containing a colorant, a water-soluble organic solvent, a surfactant, a penetrant, and water onto the surface onto which the pretreatment liquid has been applied to form an image, and a posttreatment step of applying a posttreatment liquid onto the surface onto which the inkjet ink has been applied to form a protective layer, in which the amount of pure water transferred to the coating layer of the recording medium in a contact time of 100 ms, as measured by a dynamic scanning absorptiometer, is 1 to 10 mL / m 2 and at least one of the pre-treatment liquid and the post-treatment liquid contains water and an aqueous resin, and further contains any one of colloidal silica, barium sulfate, and titanium oxide.

[0004] Patent Document 2 discloses a recording medium having at least one ink-receiving layer provided on a support, the ink-receiving layer containing inorganic fine particles, cationic organic fine particles and a water-soluble polyvalent metal salt, and the cationic organic fine particles are contained in an amount of 0.1 to 25 mass % relative to the dry mass of the ink-receiving layer in the ink-receiving layer containing the cationic organic fine particles.

[0005] However, with conventional methods, when an ink composition for inkjet recording is printed on a support (substrate), there are problems such as degradation of image quality due to the occurrence of mottling (filling in of a solid image) and bleeding in areas with a high printing rate, and problems such as the ink composition for inkjet recording penetrating to the back side of the support (substrate) and showing through to the back. Furthermore, in conventional methods, it is considered preferable to include a polyvalent metal salt in the pretreatment liquid (precoat agent) in order to improve the fixation of the pigment. However, if the pretreatment liquid contains a polyvalent metal salt, it may react with the overcoat resin used in the subsequent process (formation of the overcoat layer), causing problems such as peeling of the overcoat layer or a decrease in hardness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-073672 A [Patent Document 2] JP 2004-255772 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a precoat agent that can suppress mottle and bleeding and improve print image quality when an ink composition for inkjet recording is printed without using a polyvalent metal salt, can suppress strike-through of the ink composition for inkjet recording, and can suppress peeling of the overcoat layer and reduction in hardness during a post-process (formation of an overcoat layer). [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have conducted intensive research in light of the above-mentioned problems, and as a result, have found that a precoat agent used to form a precoat layer that receives an ink composition for inkjet recording, which contains inorganic particles of a specific particle size, an amine salt of an organic acid, a resin emulsion, and water, can solve all of the above-mentioned problems without using a polyvalent metal salt, and have thus completed the present invention.

[0009] That is, the present invention relates to a precoat agent used for forming a precoat layer that receives an ink composition for inkjet recording, the precoat agent comprising inorganic particles, an amine salt of an organic acid, a resin emulsion and water, the inorganic particles having a particle size of 1 μm to 10 μm, and not comprising a polyvalent metal salt.

[0010] In the precoat agent of the present invention, the inorganic particles are preferably porous silica particles. The amine salt of the organic acid is preferably a salt obtained by neutralizing at least one selected from the group consisting of polyacrylic acid, formic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, and lactic acid, or derivatives thereof, with an amine. The resin emulsion is preferably a styrene-acrylic emulsion and / or a vinyl acetate emulsion. The present invention also provides an ink set for ink-jet recording, comprising the above precoat agent and an ink composition for ink-jet recording. In the ink set for ink-jet recording of the present invention, the ink composition for ink-jet recording is preferably an aqueous ink-jet recording ink composition. The aqueous ink composition for ink jet recording preferably contains a pigment coated with an alkali-soluble resin, a basic compound, and a water-soluble organic solvent. The present invention also relates to a laminate having, on a substrate, a printed layer formed from the ink set for ink-jet recording, and an overcoat layer containing a resin, in this order. Effect of the Invention

[0011] The present invention can provide a precoat agent that can suppress mottle and bleeding and improve print image quality when printing an ink composition for inkjet recording without using a polyvalent metal salt, can suppress strike-through of the ink composition for inkjet recording, and can suppress peeling of the overcoat layer and reduction in hardness during a post-process (formation of an overcoat layer). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Precoat agent> The present invention relates to a precoat agent used for forming a precoat layer that receives an ink composition for inkjet recording, the precoat agent comprising inorganic particles, an amine salt of an organic acid, a resin emulsion and water, the inorganic particles having a particle size of 1 μm to 10 μm, and not comprising a polyvalent metal salt.

[0013] In the precoat agent of the present invention, the inorganic particles having a specific particle size provide a sealing effect that prevents excessive penetration into and strike-through of the substrate, as described below, after droplets of the ink composition for inkjet recording ejected from an inkjet nozzle land on the substrate, the organic acid obtained by drying the amine salt of the organic acid reacts with a compound contained in the ink composition for inkjet recording to suppress mottling and bleeding, thereby improving print image quality, and the resin emulsion provides a precoat layer that can suppress peeling off of the inorganic particles and the amine salt of the organic acid from the substrate. However, the present invention should not be construed as being limited to the above mechanism.

[0014] (Inorganic particles) The precoat agent of the present invention contains inorganic particles.

[0015] The inorganic particles include at least one selected from titanium dioxide, silica, alumina, iron oxide, iron hydroxide, tin oxide, and the like. The inorganic particles are preferably porous particles, and more preferably porous silica particles. The above inorganic particles can be used alone or in combination of two or more kinds.

[0016] The inorganic particles have a particle size of 1 μm to 10 μm. If the particle size of the inorganic particles is less than 1 μm, the effect of suppressing strike-through is reduced, whereas if it exceeds 10 μm, the smoothness of the coating film formed by the precoat agent is reduced, resulting in a deterioration in print quality. The inorganic particles more preferably have a particle size of 3 μm to 7 μm. The particle size means a volume average particle size measured by a particle size distribution measuring device using a laser diffraction scattering method as a measurement principle.

[0017] When the inorganic particles are porous particles, the average pore size is preferably 10 nm or more and 300 nm or less, and more preferably 10 nm or more and 200 nm or less. The average pore size in the present invention refers to the average pore diameter calculated from the pore volume and the specific surface area. The pore volume is preferably from 10 mL / g to 200 mL / g, and more preferably from 30 mL / g to 100 mL / g. The pore volume and specific surface area can be calculated based on the pore distribution obtained by the gas adsorption method (using nitrogen gas), specifically, the total pore volume can be calculated using the BJH method, and the specific surface area can be calculated using the BET method. An example of an apparatus capable of carrying out the gas adsorption method is Autosorb 3 (product name) manufactured by Quantachrome.

[0018] When the inorganic particles are porous particles, the porosity is not particularly limited, but is preferably, for example, from 20% to 90%, and more preferably from 30% to 85%. The porosity can be calculated based on the pore volume.

[0019] The content of the inorganic particles is preferably 1 to 10 mass %, and more preferably 3 to 7 mass %, based on the total mass of the precoat agent.

[0020] (amine salts of organic acids) The precoat agent of the present invention comprises an amine salt of an organic acid. The amine salt of an organic acid means a salt obtained by neutralizing an organic acid with an amine.

[0021] The organic acid may be at least one selected from polyacrylic acid, formic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, and lactic acid, or derivatives thereof. Among these, from the viewpoint of suppressing coating unevenness of the precoat agent and optimally exerting the effects of the present invention, a water-soluble organic acid is preferable, a water-soluble polycarboxylic acid is more preferable, and citric acid and malic acid are even more preferable.

[0022] The amine is preferably a volatile amine, and examples thereof include ammonia, mono-, di-, or trialkyl (carbon number: 1 to 4) amines, monoalkanol (carbon number: 2 or 3) amines, and mono- or dialkyl (carbon number: 1 to 4) monoalkanol (carbon number: 2 or 3) amines. More specifically, at least one selected from ammonia; mono-, di-, or trialkyl amines (having 1 to 4 carbon atoms), such as methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, propylamine, and butylamine; monoalkanolamines, such as monoethanolamine and monopropanolamine, and mono- or dialkyl monoalkanolamines (having 1 to 4 carbon atoms), such as dimethylaminoethanol, can be used. Among these, ammonia is preferred from the viewpoints of favorably imparting cohesive properties to the coating film of the precoat agent and of being less likely to remain on the substrate, as described below.

[0023] The amine salts of the above organic acids can be used alone or in combination of two or more kinds.

[0024] The content of the amine salt of the organic acid is preferably from 1 to 10% by mass, and more preferably from 3 to 7% by mass, based on the total mass of the precoat agent.

[0025] (Resin emulsion) The precoat agent of the present invention contains a resin emulsion.

[0026] Examples of the resin emulsion include emulsions of acrylic resins, ester resins, urethane resins, vinyl acetate resins, vinyl chloride resins, styrene resins, butadiene resins, and styrene-acrylic resins. Among these, from the viewpoints of providing excellent cohesiveness of the coating film of the precoat agent and favorably imparting coating film resistance, styrene acrylic emulsions and / or vinyl acetate emulsions are preferred. The above resin emulsions can be used alone or in combination of two or more kinds.

[0027] From the viewpoint of fixing the inorganic particles to a substrate, the resin emulsion preferably has a glass transition temperature of 30° C. or lower, and more preferably 20° C. or lower.

[0028] The glass transition temperature of the resin emulsion can be measured by, for example, differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012 "Method for measuring glass transition temperature of plastics" or the like.

[0029] The content of the resin emulsion is preferably 0.1 to 10 mass %, and more preferably 0.5 to 5 mass %, in terms of solid content, relative to the total mass of the precoat agent.

[0030] Examples of the resin emulsion include those in which the above-mentioned resins are emulsified in an aqueous medium described later using a low molecular weight emulsifier, those in which the above-mentioned resins are emulsified in an aqueous medium described later using a polymeric emulsifier, and those in which the resins are emulsified in an aqueous medium described later by self-emulsification.

[0031] Examples of the low molecular weight emulsifier include fatty acid esters of monosaccharides or polysaccharides, polyglycerol fatty acid esters, organic acid monoglycerides, propylene glycol fatty acid esters, polyglycerol condensed ricinoleic acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, alkylbenzene sulfonates, alkanesulfonates, α-olefin sulfonates, polyoxyethylene alkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, alkyl phosphates, tetraalkylammonium salts, alkylbenzyldimethylammonium salts, fatty acid amidoamines, alkylpyridinium salts, alkylbetaines, and alkylamine oxides.

[0032] (water) The precoat agent of the present invention contains water. As the water, commercially available purified water or the like can be used.

[0033] From the viewpoint of providing suitable fluidity and suitable abrasion resistance to the coating film of the precoat agent, the water is preferably contained in an amount of 50 to 95 mass % and more preferably 70 to 90 mass % based on the mass of the precoat agent. The water content is the total value of the water content contained in the resin emulsion and the water content other than the aqueous medium contained in the resin emulsion.

[0034] (others) The precoat agent of the present invention preferably contains a surfactant, a thickener, and a pH adjuster, as necessary.

[0035] The above surfactant is added to impart leveling properties, and any known surfactant can be appropriately selected and used as long as it does not impair the performance of the precoat agent of the present invention.

[0036] The thickener is not particularly limited as long as it does not react with the organic acid, and any known nonionic or anionic thickener can be appropriately selected and used.

[0037] As the pH adjuster, any known pH adjuster can be appropriately selected and used, and from the viewpoint of volatility, ammonia is a preferred example.

[0038] The content of each of the surfactant, thickener, and pH adjuster is, for example, 0.01 to 5% by mass relative to the total mass of the precoat agent.

[0039] In addition to the components described above, the precoat agent of the present invention may contain, as necessary, known additives such as dispersants, dispersion assistants, wetting agents, defoamers, antifungals, and rust inhibitors.

[0040] On the other hand, the precoat agent of the present invention does not contain a polyvalent metal salt in order to suppress peeling or a decrease in hardness of the overcoat layer, which will be described later. The polyvalent metal salt is composed of divalent or higher polyvalent metal ions and anions that bind to these polyvalent metal ions, and is soluble in water. Examples of polyvalent metal ions include Ca 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Zn 2+ , B.A. 2+ , etc. Examples of anions include Cl. - , NO 3- , I - , Br - , ClO 3- , etc.

[0041] (Method of manufacturing precoat agent) The method for producing the precoat agent of the present invention is not particularly limited. For example, the precoat agent can be produced by adding additives, etc., as necessary, to the above-mentioned components and kneading them.

[0042] From the viewpoint of coatability, the precoat agent of the present invention preferably has a viscosity measured with a Zahn Cup No. 3 (manufactured by Rigo Co., Ltd.) of 10 to 40 seconds, and more preferably 15 to 25 seconds.

[0043] The precoating agent of the present invention preferably has a pH of 7 to 9 from the viewpoints of material compatibility and storage stability.

[0044] <Ink set for inkjet recording> The ink set for ink-jet recording of the present invention contains the precoat agent of the present invention and an ink composition for ink-jet recording. The ink composition for ink-jet recording will now be described.

[0045] The ink set for ink-jet recording of the present invention contains an ink composition for ink-jet recording.

[0046] The ink composition for ink jet recording is preferably a water-based ink composition for ink jet recording. The aqueous ink composition for ink jet recording preferably contains a pigment coated with an alkali-soluble resin, a basic compound, and a water-soluble organic solvent.

[0047] (Pigments) Examples of the pigment include various inorganic pigments and organic pigments that are generally used in ink-jet inks.

[0048] Examples of the inorganic pigments include colored pigments (including achromatic colored pigments such as white and black) such as titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, ultramarine, Prussian blue, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc.

[0049] 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.

[0050] As the above pigments, particularly from the viewpoint of enabling the expression of vivid hues, specific examples of preferred pigments include red pigments such as CI Pigment Red 5, 7, 12, 57:1, 122, 146, 202, 242, 282, etc.; blue pigments such as CI Pigment Blue 1, 2, 15:3, 15:4, 16, 17, 60, etc.; purple pigments such as CI Pigment Violet 19 and 23, etc.; yellow pigments such as CI Pigment Yellow 12, 13, 14, 17, 74, 83, 93, 128, 139, 151, 154, 155, 180, 185, 213, etc.; black pigments such as CI Pigment Black 7 (carbon black), green pigments such as CI Pigment Green 7 and 36, and orange pigments such as CI Pigment Orange 34 and 71, etc.

[0051] (alkali soluble resin) As the alkali-soluble resin for coating the pigment, an alkali-soluble resin that satisfies the following (a) to (c) can be used. (a) The acid value of the alkali-soluble resin is 40 to 300 mg KOH / g. (b) 50 to 90% of the acid groups of the alkali-soluble resin are neutralized with a basic compound. (c) The alkali-soluble resin contains, as a constituent unit monomer, lauryl (meth)acrylate in an amount of 20 to 40 mass % in the alkali-soluble resin, and further contains a monomer having an aromatic ring, preferably a styrene-based monomer.

[0052] As such an alkali-soluble resin, for example, a copolymer having a monomer having a carboxyl group as a constituent unit and further having lauryl (meth)acrylate and a monomer having an aromatic ring in order to improve the adsorptivity to the pigment, or a copolymer obtained by reacting these monomers together with other polymerizable monomers as necessary, can be used.

[0053] 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.

[0054] Examples of the monomer containing a hydrophobic group for improving the adsorption to the pigment include lauryl (meth)acrylate, and examples of the monomer having an aromatic ring include styrene-based monomers such as styrene, α-styrene, and vinyltoluene, and benzyl (meth)acrylate. Here, the styrene-based monomer refers to a compound having a styrene skeleton and may have any substituent. The alkali-soluble resin preferably contains 30 to 60% by mass of a monomer having an aromatic ring, preferably a styrene-based monomer.

[0055] From the viewpoint of dispersion stability and solidification, the alkali-soluble resin preferably contains 20 to 40 mass% of lauryl (meth)acrylate. Although stearyl (meth)acrylate does not have to be used, it is also possible to use stearyl (meth)acrylate together with lauryl (meth)acrylate within a range that does not impair the effect of using lauryl (meth)acrylate.

[0056] In addition, other polymerizable monomers that can be used as necessary within a range that does not decrease performance include (meth)acrylic acids such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and hexyl (meth)acrylate, hydroxyethyl (meth)acrylate, acrylamide, N-methylol acrylamide, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxystearyl (meth)acrylate, dodecyl vinyl ether, vinyl 2-ethylhexanoate, vinyl laurate, vinyl stearate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate.

[0057] 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 resulting aqueous dispersion of the pigment coated with the alkali-soluble resin may decrease, whereas if it is higher than 300 mgKOH / g, the hydrophilicity may become too high, resulting in decreased storage stability and water resistance.

[0058] It is preferable that 50 to 90% of the acid groups of the alkali-soluble resin are neutralized with a basic compound. If the neutralization is less than 50%, the dispersion stability may decrease, and if it exceeds 90%, the storage stability and water resistance may decrease.

[0059] The molecular weight of the alkali-soluble resin is preferably a weight average molecular weight of 3,000 to 100,000, and more preferably 10,000 to 50,000. If 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 layer tend to decrease, while if it exceeds 100,000, the viscosity increases, which is not preferable.

[0060] The acid value of the above-mentioned alkali-soluble resin is a theoretical acid value obtained by arithmetically calculating the number of milligrams of potassium hydroxide theoretically required to neutralize 1 g of the alkali-soluble resin based on the composition of the monomers used to synthesize the alkali-soluble resin.

[0061] The weight average molecular weight of the alkali-soluble resin can be measured by gel permeation chromatography (GPC). As an example, chromatography can be performed using a GPC apparatus such as Waters 2690 (manufactured by Waters Corporation) and a column such as PLgel 5μ MIXED-D (manufactured by Polymer Laboratories), and the weight average molecular weight can be calculated in terms of polystyrene.

[0062] (Basic compounds) Examples of the basic compound that neutralizes the acid group of the alkali-soluble resin include inorganic basic compounds such as sodium hydroxide and potassium hydroxide, and organic basic compounds such as ammonia, methylamine, ethylamine, monoethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, morpholine, N-methylmorpholine, and N-ethylmorpholine. These basic compounds can be used alone or in combination of two or more. Among them, alkanolamines such as monoethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine are preferred from the viewpoint of pigment dispersion.

[0063] (Difunctional or higher crosslinking agents) The bifunctional or higher crosslinking agent used in the production of the coated pigment is used to appropriately crosslink the alkali-soluble resin. The crosslinking agent of the present invention is a crosslinking agent having two or more reactive functional groups, and the molecular weight of the crosslinking agent is preferably in the range of 100 to 2,000 from the viewpoints of ease of reaction and storage stability.

[0064] The reactive functional group is preferably one or more selected from the group consisting of an epoxy group, a hydroxyl group, and an aryl group. Among them, an epoxy group is preferred from the viewpoints of viscosity and tolerance, and a bifunctional epoxy compound is more preferred. Specific examples of the bifunctional or higher epoxy compounds include Epolite 40E, 100E, 200E, 400E, 70P, 200P, 400P, 1500NP, 1600, and 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, and EX-622 (manufactured by Nagase ChemteX Corporation).

[0065] (Manufacturing of coated pigments) The above-mentioned coated pigment is prepared by dissolving or dispersing an alkali-soluble resin, in which an acid group has been neutralized with a basic compound, and a pigment in an aqueous solvent, and then salting out or the like of the alkali-soluble resin to make it into an insolubilized resin and to adhere it to the surface of the pigment. 50 to 90% of the acid groups in the attached insolubilized resin are neutralized. A dispersion is obtained from the pigment coated with the obtained alkali-soluble resin, and a crosslinking agent is added to the dispersion, which is then heated to crosslink and insolubilize the alkali-soluble resin coating the pigment surface, thereby producing a coated pigment. In this case, the crosslinked alkali-soluble resin obtained has a crosslinking rate of 10 to 90%, preferably 20 to 80%, more preferably 30 to 70%, and even more preferably 35 to 50% of the theoretical acid value of the alkali-soluble resin. If the crosslinking rate is less than 10, the coating strength on the pigment may be insufficient, and if it exceeds 90%, the dispersion stability of the pigment may be impaired.

[0066] (Water-soluble organic solvent) The water-soluble organic solvent is used together with water as an aqueous medium. The water is preferably ion-exchanged water or distilled water from which metal ions and the like have been removed. Furthermore, by incorporating a water-soluble organic solvent, it may be possible to impart better inkjet printing suitability in terms of storage stability, ejection stability, ink flying properties, etc. Examples of such water-soluble organic solvents include monoalcohols, polyhydric alcohols, lower alkyl ethers of polyhydric alcohols, ketones, ethers, esters, nitrogen-containing compounds, etc. These may be used alone or in combination of two or more.

[0067] Specific examples of the monoalcohols include methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonyl alcohol, n-decanol, or isomers thereof, cyclopentanol, cyclohexanol, etc., and preferred are alcohols in which the alkyl group has 1 to 6 carbon atoms. Specific 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, and thiodiglycol. Specific examples of the lower alkyl ethers of the polyhydric alcohols 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, 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 glycol mono-n-butyl ether, and the like. Specific examples of the ketones include acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, and cyclohexanone. Specific examples of the ethers include isopropyl ether, n-butyl ether, tetrahydrofuran, tetrahydropyran, and 1,4-dioxane. 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 cyclic esters such as ε-caprolactone and ε-caprolactam. Examples of the nitrogen-containing compounds include urea, pyrrolidone, N-methyl-2-pyrrolidone, and octylpyrrolidone. The content of the water-soluble organic solvent in the aqueous pigment-type inkjet ink composition is preferably 20 to 40% by mass. Furthermore, when the medium is a low absorbency medium (coated paper, etc.), it is preferable to use a solvent that easily penetrates the low absorbency medium.

[0068] (others) Regarding additives that can be used in the aqueous ink composition for ink jet recording and the manufacturing method, for example, the additives and manufacturing method disclosed in JP-A-2017-149906 can be appropriately selected and used.

[0069] The ink set for ink-jet recording of the present invention can be used by separately housing the precoat agent of the present invention and the ink composition for ink-jet recording in an ink cartridge or the like.

[0070] In the ink set for ink-jet recording of the present invention, a precoat layer is formed using the precoat agent of the present invention, and then the ink composition for ink-jet recording is printed. By using the ink composition for inkjet recording in this manner, when the ink composition for inkjet recording is printed, mottling and bleeding can be suppressed to improve the print quality, strike-through of the ink composition for inkjet recording can be suppressed, and peeling and a decrease in hardness of the overcoat layer described later can be suppressed.

[0071] <Laminate> The laminate of the present invention has, on a substrate, a printed layer formed from the ink set for ink-jet recording, and an overcoat layer containing a resin, in this order.

[0072] The substrate is not particularly limited as long as it is used as a printing medium, and examples thereof include paper sheets such as thin paper, plain paper, reinforced paper, and resin-impregnated paper, titanium paper, polyethylene terephthalate sheets, glycol-modified polyethylene terephthalate sheets (PETG sheets), polyvinyl chloride sheets, polyethylene sheets, acrylonitrile butadiene styrene sheets, and polypropylene sheets, as well as composite sheets thereof. Examples of wood substrates for wood decorative panels include known materials such as plywood, particle board, hardboard, and medium density fiberboard (MDF), which have traditionally been used as wood substrates for decorative panels, furniture, building materials, and the like.

[0073] The printed layer has, in this order from the substrate side, a precoat layer formed from the precoat agent of the present invention, and an ink layer formed from the ink composition for inkjet recording.

[0074] Examples of a method for applying the precoat agent of the present invention onto the substrate include coating methods using various coating devices such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, and an inkjet.

[0075] The amount of the precoat agent applied is 0.1 to 20 g / m2 in terms of solid content. 2 From the viewpoint of favorably imparting coating film resistance, the solid content is preferably 0.1 to 15 g / m 2 It is more preferable to set the above.

[0076] The method for drying the surface coated with the precoat agent may be a dryer commonly used in this field, such as a hot air dryer. The surface coated with the precoat agent may be in a completely dried state or a semi-dried state.

[0077] The ink composition for ink-jet recording is preferably applied by an ink-jet method.

[0078] The coating amount of the ink composition for inkjet recording is 0.1 to 20 g / m in terms of solid content. 2 From the viewpoint of favorably imparting coating film resistance, the solid content is preferably 0.1 to 15 g / m 2 It is more preferable to set the above.

[0079] The laminate of the present invention has an overcoat layer containing a resin. By providing the overcoat layer, it is possible to obtain a printed image that is excellent in gloss and durability.

[0080] The overcoat layer contains a resin component used in known overcoat layers. Examples of such resin components include melamine resin, alkyd resin, polyamide resin, polyurethane resin, cellulose resin, (meth)acrylic resin, polyolefin resin, polyester resin, vinyl chloride resin, and vinyl acetate resin.

[0081] The overcoat layer can be formed by applying a composition for an overcoat layer that contains the resin component and an organic solvent. Examples of a method for applying the composition for the overcoat layer include coating methods using various coating devices such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, and an inkjet. The organic solvent constituting the overcoat layer composition can be appropriately selected from known organic solvents. The composition for the overcoat layer may also contain known additives such as a lubricant, an antifoaming agent, a surfactant, a leveling agent, and a pigment.

[0082] The coating amount of the composition for the overcoat layer may be appropriately adjusted as necessary. For example, the coating amount is 0.1 to 100 g / m in terms of solid content. 2 From the viewpoint of favorably imparting coating film resistance, the solid content is preferably 0.1 to 80 g / m 2 It is more preferable to set the above.

[0083] The laminate of the present invention has a printing layer formed from an ink set containing the above-mentioned precoat agent of the present invention, and therefore has good print image quality, can suppress strike-through of the ink composition for inkjet recording, and can suppress peeling of the overcoat layer and a decrease in hardness. EXAMPLES

[0084] Examples are given below to explain the present invention in more detail, but the present invention is not limited to only these examples. Unless otherwise specified, “%” means “mass %” and “part” means “mass part”.

[0085] The materials used in the examples and comparative examples are as follows.

[0086] <Inorganic particles> Casilia 310 (porous silica, particle size 4 μm, pore volume 60 mL / g, average pore diameter 21 nm, manufactured by Fuji Silysia Chemical Ltd.) Casilia 380 (porous silica, particle size 9 μm, pore volume 60 mL / g, average pore diameter 21 nm, manufactured by Fuji Silysia Chemical Ltd.) ST-ZL (colloidal silica (non-porous), particle size 80 nm, manufactured by Nissan Chemical Industries, Ltd.) Casilia 470 (porous silica, particle size 14 μm, pore volume 1.25 mL / g, average pore diameter 14 nm, manufactured by Fuji Silysia Chemical Ltd.) <Organic acid amine salt> Ammonium citrate tribasic Ammonium malate dibasic Ammonium lactate <Organic acid> Citric acid <Organic acid metal salt> Sodium citrate tribasic <Polyvalent metal salt> Calcium acetate <Resin emulsion> Joncryl PDX-7741 (solid content 50 mass%, styrene-acrylic emulsion, manufactured by BASF, glass transition temperature 0 °C) Rekabond S401 (solid content 50 mass%, vinyl acetate emulsion, manufactured by Japan Coating Resin Co., Ltd., glass transition temperature <0 °C) <Surfactant> Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) <Thickener> Primal ASE-95NP (polyacrylic acid, manufactured by DOW, anionic) <pH adjuster> Aqueous NH3 <Water> purified water

[0087] (Examples 1 to 13, Comparative Examples 1 to 9) The above materials were mixed in the mixing ratios shown in Table 1 and thoroughly stirred to prepare a mixture, which was then filtered through a #200 mesh metal filter to prepare the precoat agents of the examples and comparative examples. In addition, the precoat agents of Comparative Examples 6 and 9 had such low dispersion stability of the various materials that it was not possible to carry out the various evaluations described below.

[0088] <Preparation of aqueous ink composition for ink jet recording> (Water-based resin varnish) 20 parts by mass of an acrylic acid / n-butyl acrylate / benzyl methacrylate / styrene copolymer having a glass transition temperature of 40°C, a weight average molecular weight of 30,000, and an acid value of 185 mgKOH / g was dissolved in a mixed solution of 2.5 parts by mass of potassium hydroxide and 77.5 parts by mass of water to obtain an aqueous resin varnish with a solid content of 20%.

[0089] (Preparation of Water-Based Black Ink) 23.7 parts by mass of the above water-based resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for dispersing pigments. 12 parts by mass of carbon black (product name Printex 90, manufactured by Degussa) was further added to this varnish, stirred and mixed, and then milled in a wet circulation mill to prepare a water-based black ink base.

[0090] (Preparation of Water-Based Yellow Ink) 23.7 parts by mass of the above-mentioned water-based resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for dispersing pigments. 12 parts by mass of a yellow pigment (product name Novapalm Yellow 4G01, manufactured by Clariant) was further added to this varnish, stirred and mixed, and then milled in a wet circulation mill to prepare a water-based yellow ink base.

[0091] (Preparation of Water-Based Magenta Ink Base) 23.7 parts by mass of the above-mentioned aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for dispersing pigments. 12 parts by mass of magenta pigment (product name Inkjet Magenta E5B02, manufactured by Clariant) was further added to this varnish, stirred and mixed, and then milled in a wet circulation mill to prepare an aqueous magenta ink base.

[0092] (Preparation of Water-Based Cyan Ink) 23.7 parts by mass of the above-mentioned aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for dispersing pigments. 12 parts by mass of a cyan pigment (product name Heliogen Blue L7101F, manufactured by BASF) was further added to this varnish, stirred and mixed, and then milled in a wet circulation mill to prepare an aqueous cyan ink base.

[0093] (Preparation of Black Ink Composition) Of the materials described below, the ones except for the water-based black ink base were mixed in the amounts shown below and thoroughly stirred, and then 33 parts by mass of the water-based black ink base was added with stirring. After sufficient stirring, the mixture was filtered through a #3500 mesh metal filter and degassed using a hollow fiber membrane to prepare a water-based black ink. Water-based black ink base: 33 parts by weight Surfactant (Olfine E1010, manufactured by Nissin Chemical Co., Ltd.): 0.5 parts by mass Glycerin: 15 parts by weight Diethylene glycol: 14.5 parts by mass Water: 37 parts by mass

[0094] (Preparation of Yellow Ink Composition) A yellow ink composition was prepared in the same manner as in the preparation of the black ink composition, except that the aqueous black ink base was changed to an aqueous yellow ink base.

[0095] (Preparation of Magenta Ink Composition) A magenta ink composition was prepared in the same manner as in the preparation of the black ink composition, except that the aqueous black ink base was changed to an aqueous magenta ink base.

[0096] (Preparation of Cyan Ink Composition) A cyan ink composition was prepared in the same manner as in the preparation of the black ink composition, except that the aqueous black ink base was changed to an aqueous cyan ink base.

[0097] (Preparation of Overcoat Layer Composition) The materials described below were mixed in the amounts shown below and thoroughly stirred to prepare a mixture. This mixture was filtered through a #200 mesh metal filter to prepare an overcoat layer composition. Dimethylolmelamine S260 (manufactured by Nippon Carbide Corporation): 50 parts by weight Surfactant (Surfynol 440, manufactured by Nissin Chemical Industry Co., Ltd.): 1 part by mass 2-pyrrolidone: 10 parts by mass Water: 39 parts by mass

[0098] <Evaluation of physical properties of pre-coating agent> (Back bleed) The precoat agents prepared in the Examples and Comparative Examples were applied onto paper using a 0.1 mm bar coater and dried at 80°C for 3 minutes, after which each aqueous ink composition for inkjet recording was filled into the cartridge of an inkjet printer PX105 (manufactured by Epson Corporation), printing was performed, and the presence or absence of strike-through was confirmed and evaluated according to the following criteria. The results are shown in Table 1. In addition, ◯ and △ were evaluated as passing. ○: No bleed-through is observed △: A small amount of bleed-through is observed ×: A large amount of bleed-through is observed

[0099] (Bleed) The precoat agents prepared in the Examples and Comparative Examples were applied onto paper using a 0.1 mm bar coater and dried at 80°C for 3 minutes, after which each aqueous ink composition for inkjet recording was filled into the cartridge of an inkjet printer PX105 (manufactured by Epson Corporation), printing was performed, and the presence or absence of bleeding (intercolor bleeding) was confirmed and evaluated according to the following criteria. The results are shown in Table 1. In addition, ◯ and △ were evaluated as passing. ○: No bleeding observed △: A small amount of bleeding is observed. ×: A large amount of bleeding is observed

[0100] (Motaling) The precoat agents prepared in the Examples and Comparative Examples were applied onto paper using a 0.1 mm bar coater and dried at 80°C for 3 minutes. Each aqueous ink composition for inkjet recording was then loaded into the cartridge of an inkjet printer PX105 (manufactured by Epson Corporation), 100% solid printing was performed, and the presence or absence of streaks in the solid areas was evaluated according to the following criteria. The results are shown in Table 1. In addition, ◯ and △ were evaluated as passing. ○: No streaks are visible in the solid area △: A small amount of streaks are visible ×: Many streaks are visible

[0101] <Overcoat suitability> In the above-mentioned examples and comparative examples, for printed matter that did not receive an x ​​rating for strike-through, bleeding, or mottling, the composition for the overcoat layer was applied twice using a 0.3 mm bar coater and reacted at 150°C for 10 minutes to form an overcoat layer. Thereafter, the coating layer was wiped 10 times with a nonwoven fabric soaked in hydrochloric acid (1N), and the surface condition of the overcoat layer was visually confirmed. Incidentally, a sample on which an overcoat layer was formed and rated as "good" was determined to have been able to suppress peeling and a decrease in hardness. ○: No peeling or dissolution of the overcoat layer was observed. ×: Peeling or dissolution of the overcoat layer is observed.

[0102] [Table 1]

[0103] In an example using a precoat agent containing inorganic particles, an amine salt of an organic acid, a resin emulsion, and water, wherein the inorganic particles have a particle size of 1 μm to 10 μm, it was confirmed that, even without using a polyvalent metal salt, when the ink composition for inkjet recording is printed, mottling and bleeding can be suppressed to improve the print image quality, strike-through of the ink composition for inkjet recording can be suppressed, and peeling of the overcoat layer and reduction in hardness can be suppressed when the overcoat layer is formed. [Industrial Applicability]

[0104] It is possible to provide a precoat agent that can suppress mottle and bleeding when printing an ink composition for inkjet recording, thereby improving print image quality, can suppress strike-through of the ink composition for inkjet recording, and can suppress peeling of the overcoat layer and reduction in hardness during a post-process (formation of an overcoat layer), even without using a polyvalent metal salt.

Claims

1. A precoat agent used for forming a precoat layer that receives an ink composition for ink-jet recording, comprising: The composition comprises inorganic particles, an amine salt of an organic acid, a resin emulsion, and water, The inorganic particles have a particle size of 1 μm to 10 μm, A precoat agent that does not contain polyvalent metal salts.

2. The precoat agent according to claim 1 , wherein the inorganic particles are porous silica particles.

3. 3. The precoat agent according to claim 1, wherein the amine salt of an organic acid is a salt obtained by neutralizing at least one selected from the group consisting of polyacrylic acid, formic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, and lactic acid, and derivatives thereof, with an amine.

4. 4. The precoat agent according to claim 1, wherein the resin emulsion is a styrene-acrylic emulsion and / or a vinyl acetate emulsion.

5. An ink set for ink jet recording, comprising the precoat agent according to any one of claims 1 to 4 and an ink composition for ink jet recording.

6. The ink set for ink-jet recording according to claim 5 , wherein the ink composition for ink-jet recording is a water-based ink-jet recording ink composition.

7. 7. The ink set for ink jet recording according to claim 6, wherein the aqueous ink composition for ink jet recording comprises a pigment coated with an alkali-soluble resin, a basic compound, and a water-soluble organic solvent.

8. A laminate comprising, on a substrate, a printed layer formed from the ink set for ink-jet recording according to any one of claims 5 to 7, and an overcoat layer containing a resin, in that order.

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