Method of manufacturing inkjet printed materials

Abstract

To improve the coating durability of the printed layer using water-based inkjet ink in inkjet printed materials. [Solution] A method for producing an inkjet printed material, comprising: a primer coating step of applying an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt to a substrate and drying it to create a primer-coated material; an inkjet printing step of printing an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment having a glass transition temperature (Tg) of -20 to 50°C onto the primer-coated material using an inkjet device and drying it to produce an inkjet printed material; and a heat treatment step of performing a heat treatment on the inkjet printed material while exposing it to moisture.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an inkjet printed matter using an aqueous inkjet ink.

Background Art

[0002] Inkjet inks are used to form a printed layer by ejecting ink droplets onto various recording media and causing them to adhere, and are roughly classified into aqueous inks, solvent-based inks, curable inks, etc. Aqueous inkjet inks mainly contain water and have advantages such as low environmental impact.

[0003] On the other hand, the resistance of the coating film of aqueous inkjet inks, for example, hardness and strength such as dry rub resistance, and moisture resistance and water resistance such as wet rub resistance and retort resistance, may not be sufficient. Therefore, printed matters printed with aqueous inkjet inks are often used by preventing the printed surface from being exposed to the outside, for example, by laminating a laminate film on the printed surface. For example, when an inkjet printed matter using an aqueous inkjet ink is used as a packaging container, it is common to perform so-called reverse printing with the aqueous inkjet ink, and the printed surface is often made into a packaging container without being exposed to the outside.

[0004] Also, an inkjet printing method has been proposed in which a pretreatment liquid (primer) is applied before applying an aqueous inkjet ink to a recording medium (see Patent Documents 1 and 2). Patent Document 1 proposes that a reaction liquid containing a reactant that enhances the aggregation effect is adhered to a recording medium, and then a colored ink and a clear ink are adhered, thereby enhancing the aggregation property of the adhered colored ink and clear ink and improving the image quality of the printed image. Patent Document 2 discloses an ink set of an aqueous primer composition and an aqueous inkjet ink composition; an aqueous primer composition and an aqueous inkjet ink composition are applied to a resin film as a recording medium, and further, a laminate film is laminated on the printed surface to obtain a laminate film with high laminate strength. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-196177 [Patent Document 2] Japanese Patent Publication No. 2018-203905 [Overview of the project] [Problems that the invention aims to solve]

[0006] As mentioned above, the printed layer of inkjet printed materials printed with water-based inkjet ink has low coating durability, making it susceptible to abrasion due to friction or peeling when exposed to humidity or moisture. Therefore, there have been attempts to improve the physical properties of inkjet printed materials by applying a primer before printing with water-based inkjet ink, but this has not been sufficient to adequately improve the coating properties of the printed layer itself. Thus, the present invention aims to improve the coating durability of the printed layer of printed materials using water-based inkjet ink. [Means for solving the problem]

[0007] In other words, the first aspect of the present invention relates to a method for manufacturing inkjet printed materials as described below. [1] A primer coating step in which an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt is applied to a substrate and dried to create a primer coating; and the primer A method for producing an inkjet printed material, comprising: an inkjet printing step of printing an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment having a glass transition temperature (Tg) of -20 to 50°C onto a coated material using an inkjet printing apparatus, and drying it to produce an inkjet printed material; and a heat treatment step of performing a heat treatment on the inkjet printed material while exposing it to moisture.

[0008] The present invention preferably relates to a method for manufacturing inkjet printed materials as described below. [2] The method for manufacturing an inkjet printed material according to [1], wherein the heat treatment is a steam treatment or a hot water immersion treatment. [3] The method for producing an inkjet printed material according to [1] or [2], wherein the binder resin contained in the aqueous primer composition contains an acrylic resin and / or a vinyl acetate resin. [4] A method for producing an inkjet printed material according to any one of [1] to [3], wherein the aqueous primer composition contains a calcium salt. [5] A method for producing an inkjet printed material according to any one of [1] to [4], wherein the aqueous resin emulsion contained in the aqueous inkjet ink composition contains a styrene-acrylic resin. [6] A method for producing an inkjet printed material according to any one of [1] to [5], wherein the glass transition temperature (Tg) of the aqueous resin emulsion contained in the aqueous inkjet ink composition is 9 to 50°C. [7] The method for manufacturing an inkjet printed material according to any one of [1] to [6] above, wherein the substrate is a resin film, metal, or corrugated cardboard. [8] The method for manufacturing an inkjet printed material according to any one of [1] to [7] above, wherein the inkjet printed material is a surface-printed printed material.

[0009] The second aspect of the present invention relates to the inkjet printing apparatus described below. [9] An inkjet printing apparatus comprising a primer coating means, an inkjet printing means, and a heat treatment means: The primer application means applies an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt to a substrate and dries it to provide a primer-coated product; the inkjet printing means prints an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment having a glass transition temperature (Tg) of -20 to 50°C onto the primer-coated product and dries it to provide an inkjet-printed product; and the heat treatment means heat-treats the inkjet-printed product while exposing it to moisture to provide an inkjet printing apparatus. [Effects of the Invention]

[0010] According to the present invention, the resistance of various coatings in the ink-printed layer of an inkjet printed material using aqueous inkjet ink can be improved. Therefore, according to the present invention, an inkjet printed material using aqueous inkjet ink can be used as a surface-printed material, etc., in a state where the printed surface can come into contact with the outside. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram illustrating the overview of the inkjet printing apparatus of the present invention. [Modes for carrying out the invention]

[0012] 1. About the manufacturing method of inkjet printed materials The present invention provides a method for manufacturing an inkjet printed material, comprising, in this order: 1) a primer application step, 2) an inkjet printing step, and 3) a heat treatment step.

[0013] 1-1. Primer application process The primer application step in the method for manufacturing an inkjet printed material of the present invention includes applying an aqueous primer composition to a substrate to be printed and drying it.

[0014] 1-1-1. Printing substrate Examples of the substrate to be printed in the method for manufacturing an inkjet printed matter of the present invention are not particularly limited, but include polyethylene terephthalate (PET) films, polypropylene films, poly plastic substrates such as vinyl chloride sheets; metal substrates such as aluminum; cardboard; coated papers such as art paper, inkjet dedicated paper, inkjet glossy paper; uncoated papers such as plain paper, offset paper; fabrics such as cotton, etc. are included. Preferably, the substrate to be printed may be a substrate for a packaging container; examples include plastic films, metals, cardboard, etc.

[0015] 1-1-2. Aqueous primer composition The aqueous primer composition in the primer coating step contains a binder resin, a water-soluble polyvalent metal salt, and water, and may contain other optional components (hydrazine derivatives, chlorinated polyolefins, etc.). The main component of the aqueous primer composition is water, and the water content in the aqueous primer composition is usually 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more.

[0016] 1-1-2A. Binder resin The binder resin exists as an emulsion or is dissolved in the aqueous primer composition. Examples of the binder resin include acrylic resins, vinyl acetate resins, polyester resins, polyurethane resins, polyvinyl chloride resins, polybutadiene resins, polyolefin resins, etc.; preferably, it is an acrylic resin and / or a vinyl acetate resin.

[0017] The binder resin content in the aqueous primer composition is preferably 0.5% by mass or more, more preferably 1% by mass or more; on the other hand, it is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Including a binder resin improves the adhesion of the aqueous primer composition to the substrate to be printed, but if the binder resin content is excessively high, the storage stability of the aqueous primer composition may decrease.

[0018] Acrylic resins include unsaturated carboxylic acids such as (meth)acrylic acid and (anhydride) maleic acid as monomers; (meth)acrylic acid esters having aliphatic hydrocarbon groups such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, oleyl (meth)acrylate, and eicosyl (meth)acrylate; 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and (meth)acrylic acid as monomers; The resin is obtained by polymerizing (meth)acrylic acid ester compounds having a hydroxyalkyl group such as 2-hydroxypropyl lylate and 3-hydroxypropyl (meth)acrylic acid; (meth)acrylamide, acrylonitrile, olefin compounds, etc.; styrene monomers such as styrene, α-methylstyrene, vinyltoluene, dimethylstyrene, ethylstyrene, isopropylstyrene, t-butylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, fluorostyrene, and styrene; benzyl (meth)acrylate monomers such as benzyl (meth)acrylate; and phenyl (meth)acrylate monomers such as phenyl (meth)acrylate. These acrylic resins may be used individually or in combination of two or more types.

[0019] The glass transition temperature (Tg) of the acrylic resin is preferably -30 to 120°C, the weight-average molecular weight is preferably 3000 to 50000, and the acid value is preferably 30 to 500 mg KOH / g.

[0020] Vinyl acetate resins are resins containing 50 mol% or more of vinyl acetate monomer. Vinyl acetate resins may include vinyl acetate homopolymers or copolymers of vinyl acetate and other monomers. Vinyl acetate resins may be partially saponified or 100% saponified as needed. Examples of other monomers include ethylene, propylene; vinyl halides such as vinyl chloride, vinylidene chloride, and vinyl fluoride; alkyl esters of (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, fumaric acid, and crotonic acid, and their anhydrides.

[0021] The weight-average molecular weight of the vinyl acetate resin is preferably between 3,000 and 50,000.

[0022] The binder resin in the aqueous primer composition may contain chlorinated polyolefin. Chlorinated polyolefin is a resin obtained by chlorinating a polyolefin resin, and may be an emulsion thereof. Examples of polyolefin resins that can be chlorinated include polypropylene resin, polyethylene resin, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-propylene-α-olefin copolymer, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, etc. In order to improve the storage stability of the aqueous resin emulsion, the chlorinated polyolefin may be acid-modified with (anhydride) maleic acid, etc., in which case a basic compound is added to the system before use. Two or more chlorinated polyolefin emulsions may be used in combination.

[0023] Furthermore, the degree of chlorination (chlorine content) of the chlorinated polyolefin is preferably 1 to 40% by mass of the total resin, and more preferably 10 to 30% by mass. If the degree of chlorination of the chlorinated polyolefin is too high, the polarity of the resin itself becomes excessively high, which may reduce its adhesion to the substrate to be printed when it is included in the primer composition.

[0024] The content of chlorinated polyolefin in the aqueous primer composition is not particularly limited, but from the viewpoint of adhesion of the aqueous primer composition to the substrate to be printed and storage stability of the primer composition itself, it is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, even more preferably 1% by mass or more, and may be 1.5% by mass or more in terms of solid content; on the other hand, it is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and may be 5% by mass.

[0025] 1-1-2B. Water-soluble polyvalent metal salts The water-soluble polyvalent metal salt contained in the aqueous primer composition may be a polyvalent metal salt of an organic acid and / or an inorganic acid, but is preferably a polyvalent metal salt of an organic acid. Examples of polyvalent metals include calcium, magnesium, iron, aluminum, zinc, strontium, copper, nickel, etc., but is preferably calcium and magnesium, and more preferably calcium.

[0026] Polyvalent metal salts of organic acids are, for example, polyvalent metal salts of fatty acids. As for fatty acids, the fatty acid anion RCOO - Fatty acids in which R has 1 to 30 carbon atoms are preferably mentioned. Specific examples of fatty acids include acetic acid, propionic acid, octic acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, margaric acid, stearic acid, and 12-hydroxypropyl alcohol. This includes cystearic acid, ricinoleic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, etc. Among these, the fatty acid anion RCOO- It is more preferable that the number of carbon atoms in R is between 1 and 10, and even more preferable that it is between 1 and 5. Examples of such fatty acids include acetic acid.

[0027] Polyvalent metal salts of inorganic acids are, for example, polyvalent metal salts of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and preferably polyvalent metal salts of hydrochloric acid or nitric acid. Preferred specific examples of polyvalent metal salts of inorganic acids include calcium salts such as calcium nitrate, calcium chloride, and calcium hydroxide; and magnesium salts such as magnesium chloride, magnesium hydroxide, and magnesium sulfate.

[0028] The content of the water-soluble polyvalent metal salt in the primer composition is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more; on the other hand, it is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. By adjusting the content of the water-soluble polyvalent metal salt, the primer layer and the printing layer of the aqueous inkjet ink composition formed thereon can be laminated more tightly together.

[0029] The present invention's method for producing inkjet printed materials includes a heat treatment step (steam treatment or hot water immersion treatment), but this heat treatment step can alter the water-soluble polyvalent metal salt contained in the primer layer (for example, by reacting with the aqueous resin emulsion in the aqueous inkjet ink composition) and turn it into an insoluble substance.

[0030] 1-1-2C. Hydrazine derivatives The aqueous primer composition may contain a hydrazine derivative. The hydrazine derivative has at least two hydrazine residues; for example, a compound represented by the following general formula A, Compounds represented by general formula B, dihydrazide maleate, dihydrazide fumarate, itacon Examples include acid dihydrazides, and two or more may be used in combination. Among these, adipic acid dihydrazide, sebacate acid dihydrazide, and isophthalic acid dihydrazide are more preferred. (chemical 1) General formula A TIFF2026046996000002.tif23170 (In general formula A, n represents values ​​from 1 to 10) General formula B TIFF2026046996000003.tif16170 (In general formula B, m represents 1 to 4)

[0031] The content of the hydrazine derivative in the aqueous primer composition is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1% by mass or more; on the other hand, it is preferably 10% by mass or less, and more preferably 5% by mass or less. While the hydrazine derivative can improve adhesion to the substrate to be printed, an excessive amount may reduce the storage stability of the primer composition.

[0032] 1-1-3. Application and drying of aqueous primer composition The aqueous primer composition is applied to a substrate (the substrate to be printed on) and dried to form a primer layer, thereby becoming a primer-coated product.

[0033] The means of applying the aqueous primer composition are not particularly limited. Examples of application methods include application using various coating devices such as bar coaters, blade coaters, air knife coaters, roll coaters, gravure coaters, rod blade coaters, lip coaters, curtain coaters, and die coaters. Alternatively, the aqueous primer composition may be applied using an inkjet printing device.

[0034] The amount of aqueous primer composition applied can be adjusted so that the thickness of the primer layer after drying is 0.01 to 1 μm, preferably 0.05 to 0.8 μm. If the thickness of the primer layer after drying is less than 0.01 μm, it becomes difficult to form a uniform, defect-free primer layer on the substrate. On the other hand, if the thickness of the primer layer after drying exceeds 1 μm, the drying time of the primer layer may be long, which may reduce workability and may also be economically inefficient.

[0035] The applied primer composition is dried to form a primer layer. The drying method is not particularly limited, but drying by heating is preferred. The heating temperature is approximately 30 to 80°C, and may be preferably 40 to 70°C. The drying time varies depending on the heating temperature, but is approximately 1 second to 1 minute, and may be 10 seconds or less.

[0036] 1-2. Inkjet Printing Process An aqueous inkjet ink composition is printed onto the primer-coated material obtained by the primer application process described above, and the material is dried to produce an inkjet print.

[0037] 1-2-1. Water-based ink composition for inkjet printers The aqueous inkjet ink composition contains an aqueous resin emulsion, a pigment, and water; it may also contain other components, such as wax, surfactant, water-soluble organic solvent, and pigment dispersant. The water content in the aqueous inkjet ink composition is preferably 10% by mass or more, more preferably 20% by mass or more; on the other hand, it is preferably 60% by mass or less, and more preferably 50% by mass or less.

[0038] 1-2-1A. Water-based resin emulsion Examples of aqueous resin emulsions included in aqueous inkjet ink compositions include acrylic resin emulsions, acrylic-styrene resin emulsions, acrylic-vinyl acetate resin emulsions, polyester resin emulsions, polyurethane resin emulsions, polyvinyl acetate resin emulsions, polyvinyl chloride resin emulsions, polybutadiene resin emulsions, polyethylene resin emulsions, and the like. More preferred examples of aqueous resin emulsions include acrylic resin emulsions and acrylic-styrene resin emulsions, with acrylic-styrene resin emulsions being even more preferred. The composition of the aqueous resin emulsion can improve the physical properties (such as abrasion resistance and moisture resistance) of the inkjet print layer of the resulting inkjet print.

[0039] The aqueous resin emulsion may preferably be a styrene-acrylic resin; the styrene-acrylic resin may be a copolymer of styrene, (meth)acrylic acid, and an alkyl (meth)acrylate ester. Furthermore, monomers such as acrylamide and acrylonitrile can be copolymerized as comonomers, to the extent that the effects of the styrene-acrylic resin emulsion are not impaired. Styrene-acrylic resins available from the market... Specific examples of acrylic resins include, for instance, Yodzol AD199, NeoKryl A-1092, and NeoKryl A-655.

[0040] The glass transition temperature (Tg) of aqueous resin emulsions is -20°C or higher, and -10°C or lower. It is preferable that the temperature is above 0°C, more preferably above 0°C, and even more preferably above 9°C; on the other hand, it is preferable that the temperature is 50°C or lower, and preferably below 40°C. When the glass transition temperature (Tg) of the aqueous resin emulsion is 50°C or lower, the temperature on the primer-coated surface is The film-forming properties of the ink composition are easily enhanced; on the other hand, temperatures above -20°C make it easier to improve the ejection stability of the ink composition, and also improve the physical properties (such as abrasion resistance and moisture resistance) of the inkjet print layer of the inkjet printed material obtained after the heat treatment process.

[0041] Is the glass transition temperature (Tg) of an aqueous resin emulsion the theoretical glass transition temperature, or is it the actual glass transition temperature? This can be the measured glass transition temperature. For example, if the aqueous resin emulsion is an acrylic resin or a styrene-acrylic resin, the theoretical glass transition temperature Tg is obtained by Wood's formula below. Wood's formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 + ... + W X / Tg X [In the formula, Tg1~Tg X These are monomers 1, 2, 3...x that constitute the anionic group-containing resin. Glass transition temperatures of each homopolymer, W1~W X This is the same as that of monomers 1, 2, 3...x. The polymerization fraction and Tg represent the theoretical glass transition temperature. In Wood's equation, the glass transition temperature is expressed in absolute temperature.

[0042] The actual glass transition temperature can be measured by thermal analysis. The thermal analysis method follows JIS K7121 (Method for measuring the transition temperature of plastics), and as an example, Perkin Using the Elmer Pyris1 DSC, the glass transition temperature can be measured under conditions of a heating rate of 20°C / min and a nitrogen gas flow rate of 20 ml / min.

[0043] The average particle size of the aqueous resin emulsion is preferably 500 nm or less, and more preferably 300 nm or less, from the viewpoint of improving the discharge stability of the ink composition. The average particle size of the emulsion can be determined, for example, by measuring the D50 value using a Nikkiso Microtrac particle size distribution analyzer "UPA-150" with a measurement time of 60 seconds and water as the diluent.

[0044] In an aqueous inkjet ink composition, the content of aqueous resin emulsion is preferably 1% by mass or more, and more preferably 2% by mass or more, as resin solids; on the other hand, it is preferably 10% by mass or less, and more preferably 8% by mass or less. A content of 1% by mass or more of aqueous resin emulsion as resin solids improves the appearance and various resistances of the resulting printed material; on the other hand, a content of 10% by mass or less stabilizes the inkjet ejection of the ink composition.

[0045] 1-2-1B. Pigments The pigments contained in the water-based inkjet ink composition can be conventionally used known inorganic pigments, organic pigments, etc.

[0046] Examples of inorganic pigments include carbon black, titanium dioxide, zinc oxide, lithopon, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, red iron oxide, molybdenum red, chrome vermilion, molybdate orange, lead yellow, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, dark blue, cobalt blue, cerulean blue, manganese violet, cobalt violet, ma It contains squid, etc.

[0047] Examples of organic pigments include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimimidazolone, isoindoline, and isoindolinone organic pigments.

[0048] Specific examples of organic pigments are shown in the color index: Pigment Black 7; Pigment Blue 15, 15:1, 15:3, 15:4, 15:6, 60; Pigment Green 7, 36; Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 149, 168, 177, 178, 179, 206, 207, 209, 242, 254, 255; Pigment Violet 19, 23, 2 Examples include 9, 30, 37, 40, 50; Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185; Pigment Orange 36, 43, 51, 55, 59, 61, 71, 74; and others. These pigments can be used individually or in mixtures of two or more.

[0049] The pigment content of water-based inkjet ink compositions other than white ink is preferably 1% by mass or more, more preferably 2% by mass or more; on the other hand, it is preferably 10% by mass or less, and more preferably 7% by mass or less. The pigment content of the water-based inkjet ink composition of white ink is preferably 5 to 15% by mass. Setting the pigment content above a certain level makes it easier to obtain sufficient coloring power, while setting it below a certain level makes it easier to suppress the increase in viscosity of the ink composition and ensure the fluidity of the ink.

[0050] 1-2-1C. Wax Water-based inkjet ink compositions may contain wax. The wax is preferably a hydrocarbon wax; preferred examples of hydrocarbon waxes include polyethylene wax, polypropylene wax, Fischer-Tropsch wax, carnauba wax, paraffin wax, microstarin wax, etc., which may be used alone or in combination of two or more. Polyethylene wax and / or Fischer-Tropsch wax are more preferred as the wax, and polyethylene wax is even more preferred.

[0051] Specific examples of polyethylene waxes include AQUACER507, AQUACER515, AQUACER531, AQUACER539 (all manufactured by Big Chemie Japan), Hi-Tec E-6314 (35% solids, nonionic emulsion polyethylene wax, manufactured by Toho Chemical Co., Ltd.), and Hi-Tec E-1000 (35% solids, nonionic emulsion polyethylene wax, manufactured by Toho Chemical Co., Ltd.). These may be used individually or in combination of two or more types.

[0052] The wax content in the aqueous inkjet ink composition is preferably 0.5% by mass or more, more preferably 1% by mass or more; on the other hand, it is preferably 7% by mass or less, and more preferably 5% by mass or less. The wax can improve the blocking resistance and abrasion resistance (especially dry abrasion resistance) of the printed material.

[0053] 1-2-1D. Surfactants Water-based inkjet ink compositions may contain surfactants. Examples of surfactants include acetylenediol-based surfactants, silicone-based surfactants, fluorine-based surfactants, alcohol ethoxylate-based surfactants, alcohol alkoxylate-based surfactants, etc., but acetylenediol-based surfactants may be preferred. Diol-based surfactants can improve the solid filling of printed (recorded) images in aqueous inkjet ink compositions.

[0054] Specific examples of acetylenediol-based surfactants include Surfinol 104E, Surfinol 104H, Surfinol 104A, and Surfinol 104BC, all manufactured by Evonik. Surfinol 104DPM, Surfinol 104PA, Surfinol 104P Examples include G-50, Surfinol 420, Surfinol 440; and Orfin E1004, Orfin E1010, Orfin E1020, Orfin PD-001, Orfin PD-002W, Orfin PD-004, Orfin PD-005, Orfin EXP.4001, Orfin EXP.4200, Orfin EXP.4123, Orfin EXP.4300, etc., manufactured by Nisshin Chemical Industry Co., Ltd. These may be used individually or in combination of two or more types.

[0055] The surfactant content in the aqueous inkjet ink composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more; more preferably 3% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2% by mass or less.

[0056] In the method for manufacturing inkjet printed materials of the present invention, the white aqueous inkjet ink composition may be used as a white underprint. White underprint refers to the process of printing with white ink before printing with aqueous inkjet ink compositions other than white ink, thereby concealing the color of the substrate. In this case, the surface tension of the white aqueous inkjet ink composition and the surface tension of the aqueous inkjet ink compositions other than white ink can be adjusted with a surfactant to facilitate the application of the printed layer of the aqueous inkjet ink compositions other than white ink.

[0057] 1-2-1E. Water-soluble organic solvents Water-based inkjet ink compositions may contain water-soluble organic solvents. Examples of water-soluble organic solvents include: monoalcohols such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonyl alcohol, n-decanol, cyclopentanol, and cyclohexanol; diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, heptanediol, 1,2-cyclohexanediol, octanediol, 1,9-nonanediol, and 1,10-decanediol; and tetraethylene glycol, polyethylene glycol, tetrapropylene glycol, and tetraethylene glycol. This includes odiglycol and the like, as well as monoalkyl esters, monoalkyl ethers or dialkyl ethers of these alcohols, and glycerin; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, and cyclohexanone; ethers such as isopropyl ether, n-butyl ether, tetrahydrofuran, tetrahydropyran, and 1,4-dioxane; esters such as propylene carbonate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, ethyl butyrate, dibutyl phthalate, and dioctyl phthalate; cyclic esters such as ε-caprolactone and ε-caprolactam; and cyclic amides such as N-methyl-2-pyrrolidone. The water-soluble organic solvents contained in the aqueous inkjet ink composition may be one or more alone, or two or more in combination.

[0058] The content of water-soluble organic solvents in an aqueous inkjet ink composition is preferably 20% by mass or more; on the other hand, it is preferably 60% by mass or less, and 50% by mass or less. It is more preferable that the amount be 40% by mass or less. Furthermore, the total content of water-soluble organic solvent and water in the aqueous inkjet ink composition is preferably 40% by mass or more, more preferably 50% by mass or more; on the other hand, it is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0059] 1-2-1F. Pigment Dispersant Water-based inkjet ink compositions may contain a pigment dispersant. The pigment dispersant is preferably a resin-type pigment dispersant (pigment dispersion resin). A pigment dispersion resin has hydrophobic groups (e.g., styrene or long-chain alkyl groups) within its molecule, and these hydrophobic groups provide affinity to the pigment. Examples of pigment dispersion resins include acrylic resins, styrene-acrylic resins, maleic acid resins, styrene-maleic acid resins, α-olefin-maleic acid resins, urethane resins, and ester resins. From the viewpoint of stabilizing the pigment dispersion, it is preferable to use acrylic resins, styrene-acrylic resins such as styrene-lauroyl acrylic acid copolymers, etc.

[0060] The acid value of the pigment dispersion resin is preferably 40 to 300 mg KOH / g, and more preferably 70 to 250 mg KOH / g, from the viewpoint of pigment dispersibility and dispersion stability. The weight-average molecular weight of the pigment dispersion resin is preferably 3,000 to 200,000, and more preferably 10,000 to 50,000, from the viewpoint of pigment dispersibility and dispersion stability, and from the viewpoint of imparting appropriate viscosity to the ink composition.

[0061] The content of the pigment dispersion resin in the aqueous inkjet ink composition is preferably 10 parts by mass or more, and preferably 200 parts by mass or less, per 100 parts by mass of pigment.

[0062] 1-2-2. Printing and drying of aqueous inkjet ink compositions Water-based inkjet ink compositions are printed onto a primer-coated surface using an inkjet printing device, dried to form a print layer, and produce an inkjet print. In the inkjet printing process, only a single-color water-based inkjet ink composition may be printed, or multiple-color water-based inkjet ink compositions may be printed (color printing). Alternatively, in the inkjet printing process, a white water-based inkjet ink composition may be printed (called white undercoat printing), and then other colored water-based inkjet ink compositions may be applied as overlays.

[0063] The type of inkjet printing device that can be used is not particularly limited; it may be a line head type (single pass type) or a serial head type (multi-pass type). Furthermore, a continuous type inkjet printing device may also be used, in which case a conductivity-imparting agent can be added to further adjust the conductivity of the ink composition.

[0064] The water-based inkjet ink composition is supplied to the printer head of an inkjet printing device, and droplets of the ink composition are ejected from the printer head onto the substrate to be printed. The ejection of the ink composition from the printer head onto the substrate (printing of an image) should be performed so that the film thickness after drying on the substrate is, for example, 1 to 60 μm.

[0065] When droplets of the aqueous inkjet ink composition according to the present invention land on a substrate, the water-soluble polyvalent metal salt contained in the primer layer and the binder resin contained in the aqueous inkjet ink composition interact (for example, by ionic bonding), which can suppress excessive wetting and spreading of the droplets of the aqueous inkjet ink composition on the substrate.

[0066] The water-based inkjet ink composition printed on the substrate dries to form the printed layer. The drying method is not particularly limited, but can be carried out by heating. The drying temperature can be around 60°C to 130°C, and is preferably in the range of 80°C to 120°C. The drying time depends on the drying temperature, but can be around 1 to 10 minutes, or 5 minutes or less.

[0067] 1-3. Heat treatment process The inkjet printed material obtained in the aforementioned inkjet printing process is subjected to heat treatment, specifically, heat treatment while exposed to moisture. Specific examples of heat treatment methods include, but are not limited to, steam treatment and hot water immersion treatment.

[0068] 1-3-1. Steam treatment Steam treatment refers to bringing water vapor into contact with the printed surface of an inkjet print. The temperature of the water vapor that comes into contact with the print (the temperature of the water vapor when it comes into contact with the print) is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, and may be 100°C. Steam treatment may also be pressurized steam treatment, and the steam temperature may exceed 100°C. The treatment time for steam treatment may be 0.1 seconds or more and 10 seconds or less.

[0069] The method of bringing water vapor into contact with an inkjet print is not particularly limited, but examples include filling a box with water vapor generated by a water boiling method and passing the inkjet print through the box, or directly blowing water vapor from a steam nozzle of a steam cleaner or the like onto the inkjet print. By adjusting the distance between the printed surface of the inkjet print and the steam nozzle, the temperature of the water vapor that comes into contact with the print can be adjusted.

[0070] 1-3-2. Hot water immersion treatment Hot water immersion treatment refers to immersing inkjet printed materials in hot water. The temperature of the hot water used for immersion is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and may be 90°C or higher (for example, 100°C). The immersion time may be between 0.1 seconds and 10 seconds or less.

[0071] Heat treatment of inkjet printed materials by means of steam treatment or hot water immersion treatment improves the coating properties of the printed layer. The improved coating properties include abrasion resistance in a dry state (dry abrasion resistance), abrasion resistance in a wet state (moist abrasion resistance), and abrasion resistance when exposed to heat of 100°C or higher, such as in retort tests (retort resistance).

[0072] The reason why heat treatment while exposing inkjet printed materials to moisture improves the coating properties of the printed layer is not particularly limited, but it is thought that the water-soluble metal salts contained in the primer layer, and the water-soluble pigment dispersion resin and water-soluble resin emulsion contained in the printed layer of the water-soluble inkjet ink composition, crosslink and harden due to the heat treatment, and their insolubility to water increases. However, this is not the only reason.

[0073] Conventional water-based inkjet ink compositions have made it difficult to obtain sufficient coating properties in printed layers. The present invention makes it possible to dramatically improve the coating properties by treating the substrate to be printed with a specific primer composition and subjecting the printed layer of the water-based inkjet ink composition to a specific heat treatment.

[0074] 2. Uses of inkjet printed materials The inkjet printed material of the present invention may be a surface-printed material. That is, the inkjet ink printing layer may be arranged so that it is on the outer surface. Because printed materials have high physical resistance (such as abrasion resistance) to their printed layers (the coating film made of primer composition and the printed layer made of inkjet ink), they are less likely to deteriorate even when placed on the outside.

[0075] The inkjet printed material of the present invention may be a surface-printed packaging container; for example, it may be a plastic film container, a corrugated cardboard container, an aluminum pouch container, an aluminum can, etc. Plastic film containers and aluminum pouch containers may also be used as retort packaging containers. The printed layer of the inkjet printed material of the present invention maintains its abrasion resistance even after retort treatment (exposure to 100°C or higher), and is therefore preferably used as a retort packaging container.

[0076] Furthermore, the inkjet printed material of the present invention may have a varnish for overcoating that covers the inkjet ink printing layer, or it may be a laminate in which a laminate film is laminated onto the inkjet ink printing surface.

[0077] 3. About inkjet printing equipment The inkjet printing apparatus of the present invention is capable of carrying out the above-described method for manufacturing inkjet printed materials. Preferably, the inkjet printing apparatus can carry out the above-described process for manufacturing inkjet printed materials in line, but is not limited thereto. That is, the primer application step, the inkjet printing step, and the heat treatment step may be carried out in a single apparatus, or they may be carried out in separate apparatuses.

[0078] The inkjet printing apparatus 100 of the present invention comprises a primer coating means 20, an inkjet printing means 30, and a heat treatment means 40; and more preferably, a transport means 10 for transporting a substrate 1 to be printed (see Figure 1).

[0079] The primer application means 20 can be any means for applying the aforementioned aqueous primer composition to the substrate 1 to be printed; preferably it comprises a coating apparatus 21 such as a bar coater, blade coater, air knife coater, roll coater, gravure coater, rod blade coater, lip coater, curtain coater, and die coater. Furthermore, it is preferable that the primer application means 20 comprises a drying means 22 for drying the primer composition applied to the substrate 1 to be printed. The drying means 22 may be, for example, a heated oven, a hot air dryer, or a heated fixing roller.

[0080] The inkjet printing means 30 is a means for printing the aforementioned aqueous inkjet ink composition onto the substrate 1 to be printed, and comprises at least an inkjet recording head 31. The inkjet printing means 30 may comprise one inkjet recording head 31, in which case only a single-color (e.g., black) ink composition can be printed; or it may comprise multiple (e.g., five) inkjet recording heads (31A to 31E), in which case multiple-color (e.g., white, black, yellow, magenta, cyan) ink compositions can be printed (color printing). White underprinting is also possible using a white aqueous inkjet ink composition.

[0081] The type of inkjet recording head 31 is not particularly limited and may be a piezo type, a bubble jet type, etc. Also, the nozzle of the inkjet recording head may be a single nozzle, but a multi-nozzle head is preferred.

[0082] The inkjet printing means 30 preferably includes a drying means 32 for drying the printed inkjet ink. The drying means 32 may be arranged corresponding to each of the inkjet recording heads 31, but as shown in Figure 1, it may be arranged corresponding to multiple inkjet recording heads The inkjet inks printed with the brush 31 (A-E) may be dried together. The drying means 32 may be, for example, a heated oven, a hot air dryer, a heated fixing roller, etc.

[0083] The heat treatment means 40 is a means of heat-treating the substrate 1 on which the inkjet ink has been printed, preferably while exposing it to moisture, and more specifically, a means of steam treatment or hot water immersion treatment. The heat treatment means 40 may be, for example, a device that blows steam (such as a steam cleaner), a box filled with steam, a bath containing hot water, etc.

[0084] The transport means 10 can be any means that sequentially transports the substrate to be printed 1 to the primer coating means 20, the inkjet printing means 30, and the heat treatment means 40. For example, as shown in Figure 1, it may consist of rollers 11. The inkjet printing apparatus 100 may also have a winding device for winding up the inkjet printed material (not shown). [Examples]

[0085] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "parts" means "parts by mass".

[0086] A. Preparation of primer composition Primer compositions P1 and P2 were prepared with the compositions shown in Table 1. Specifically, calcium acetate, an aqueous resin emulsion, a chlorinated polyolefin, and a surfactant were dissolved in water. The units of the values ​​in Table 1 are parts by mass. [Table 1] Acrylic emulsion: Vinibran 2687 (acrylic-based, manufactured by Nisshin Chemical Industry Co., Ltd.) Vinyl acetate emulsion: Vinibran 1002 (vinyl acetate-based, manufactured by Nisshin Chemical Industry Co., Ltd.) Chlorinated polyolefin (chlorination degree 21%): Supercron E-604 (chlorination degree 21%) (Manufactured by Nippon Paper Industries Co., Ltd.) Surfactant: Olphine E1010 (acetylenediol-based, manufactured by Nisshin Chemical Industry Co., Ltd.)

[0087] B. Preparation of aqueous inkjet ink compositions B-1. Preparation of water-based resin varnish Twenty parts by mass of an acrylic acid / n-butyl acrylate / benzyl methacrylate / styrene copolymer, with 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%.

[0088] B-2. Preparation of the ink base B-2-Bk. Preparation of water-based black ink base A resin varnish for pigment dispersion was prepared by adding 64.3 parts by mass of water to 23.7 parts by mass of the above-mentioned aqueous resin varnish and mixing. To this varnish, 12 parts by mass of carbon black (product name Printex 90, manufactured by Degussa) was added, and after stirring and mixing, the mixture was kneaded using a wet circulation mill. The following procedure was performed to prepare a water-based black ink base.

[0089] B-2-Y. Preparation of a water-based yellow ink base A resin varnish for pigment dispersion was prepared by adding 64.3 parts by mass of water to 23.7 parts by mass of the above-mentioned aqueous resin varnish and mixing. To this varnish, 12 parts by mass of yellow pigment (product name Novapalm Yellow 4G01, manufactured by Clariant) was added, and after stirring and mixing, the mixture was kneaded in a wet circulation mill to prepare an aqueous yellow ink base.

[0090] B-2-M. Preparation of water-based magenta ink base A resin varnish for pigment dispersion was prepared by adding 64.3 parts by mass of water to 23.7 parts by mass of the above-mentioned aqueous resin varnish and mixing. To this varnish, 12 parts by mass of magenta pigment (product name Inkjet Magenta E5B02, manufactured by Clariant) was added, and after stirring and mixing, the mixture was kneaded in a wet circulation mill to prepare an aqueous magenta ink base.

[0091] B-2-C. Preparation of water-based cyan ink base A resin varnish for pigment dispersion was prepared by adding 64.3 parts by mass of water to 23.7 parts by mass of the above-mentioned aqueous resin varnish and mixing. To this varnish, 12 parts by mass of cyan pigment (product name Heliogen Blue L7101F, manufactured by BASF) was added, and after stirring and mixing, the mixture was kneaded in a wet circulation mill to prepare an aqueous cyan ink base.

[0092] B-2-W. Preparation of a water-based white ink base A resin varnish for pigment dispersion was prepared by adding 20.0 parts by mass of water to 40.0 parts by mass of the above-mentioned aqueous resin varnish and mixing. To this varnish, 40 parts by mass of titanium dioxide (trade name R-960, manufactured by DuPont) was added, and after stirring and mixing, the mixture was kneaded in a wet circulation mill to prepare an aqueous white ink base.

[0093] B-3. ​​Preparation of water-based inkjet inks Water-based inkjet inks with the compositions shown in Examples 1 to 12 in Table 2 were prepared. The materials used in the preparation are listed below. <Water-based resin emulsion> • Acrylic-styrene (Tg -14℃): Iodozol AD199, acrylic-styrene emulsion, manufactured by Henkel. • Acrylic-styrene (Tg 9℃): Neoacrylic A-1092, acrylic-styrene emulsion, manufactured by DSM Neoresins. • Acrylic-styrene (Tg 33℃): Neoacrylic A-655, acrylic-styrene emulsion, manufactured by DSM Neoresins. • Acrylic-styrene (Tg-32℃): Movinyl 966A, acrylic-styrene emulsion, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. • Acrylic vinyl acetate (Tg -13℃): Vinibran 1245L, acrylic vinyl acetate emulsion, manufactured by Nisshin Chemical Co., Ltd. • Acrylic-vinyl chloride (Tg33℃): Vinibran 278L, acrylic-vinyl chloride emulsion, manufactured by Nisshin Chemical Co., Ltd. • Vinyl acetate (Tg 30℃): Vinibran GV6181, vinyl acetate emulsion, manufactured by Nisshin Chemical Co., Ltd. <Wax Emulsion> • AQUACER 539 (35% solids, manufactured by BYK) <Surfactants> • Orphine E1010 (100% solids, HLB 13-14, manufactured by Nisshin Chemical Co., Ltd.) • Orphine E1004 (100% solids, HLB 7-9, manufactured by Nisshin Chemical Co., Ltd.)

[0094] Aqueous inkjet ink compositions with the compositions shown in Table 2, Examples 1 to 12, were prepared. Specifically, an aqueous resin emulsion, a wax emulsion, a surfactant, a water-soluble organic solvent, and water were added to the ink base and mixed using a mixer.

[0095] [Table 2]

[0096] C. Manufacturing of inkjet printed materials Perform the following steps (C-1 to C-3) under the conditions shown in Tables 3 to 5, and then provide examples or comparisons. We manufactured the inkjet printed material in question.

[0097] C-1. Primer application process A primer coating was formed by applying a primer composition (P1 or P2) to a PET film (E5100, 12 μm, manufactured by Toyobo), an aluminum plate (0.3 mm thick), coated cardboard (OK Ball, 230 g / m2, manufactured by Oji Materia), or corrugated cardboard base paper (K ​​Liner, 170 g / m2, manufactured by Oji Materia) using a bar coater with a 0.1 mm wire diameter, and then heating and drying it in a 50°C oven for 5 seconds. However, the comparative example... In case 1 (Table 5), the primer-coated film was not dried.

[0098] C-2. Inkjet Printing Process Aqueous inkjet ink compositions (Examples 1 to 12) were packed into cartridges of an Epson PX105 printer, printed onto the primer coating formed in C-1, and then heated and dried in an oven at 70°C or 100°C for 3 minutes to form an ink coating. However, in Comparative Examples 1 and 2 (Table 5), the ink coating was not dried.

[0099] C-3. Heat Treatment Process <Steam Treatment> The ink coating formed in C-2 above was treated with steam using a steam cleaner, by injecting steam so that the temperature of the water vapor in contact with the ink coating was 70°C, 100°C, or 120°C (specifically, by adjusting the distance between the coating surface and the steam nozzle). The steam treatment time was set to 1 second, 5 seconds, or 10 seconds. <Hot water immersion treatment> The ink coating film formed in C-2 above was treated by immersing it in boiling water (100°C) or 80°C water for 1 second or 2 seconds. <Oven Treatment> The ink coating formed in C-2 above was treated by storing it in an oven at 100°C for 10 seconds or 30 seconds.

[0100] D. Evaluation of inkjet prints The inkjet prints obtained in each example or comparative example were evaluated according to the following criteria D-1 to D-3. The results are shown in Tables 3 to 5.

[0101] D-1. Dry friction resistance The printed surface of the printed materials obtained in each example and comparative example was rubbed with a dry cotton swab, and the dry abrasion resistance was evaluated according to the following evaluation criteria. ◎: The painted surface remained completely unsmudged even after being rubbed 200 times with a cotton swab. ○: The painted surface remained completely unsmudged even after being rubbed 100 times with a cotton swab. △: After rubbing the painted surface 100 times with a cotton swab, the color transferred to the cotton swab, and the rubbed area became slightly faded. ×: After rubbing the painted surface with a cotton swab 100 times, much of the paint peeled off in the rubbed areas.

[0102] D-2. Moisture resistance and abrasion resistance The printed surface of the printed materials obtained in each example and comparative example was rubbed with a water-moistened cotton swab, and the moisture abrasion resistance was evaluated according to the following evaluation criteria. ◎: The painted surface remained completely unsmudged even after being rubbed 100 times with a cotton swab. ○: The painted surface remained completely unsmudged even after rubbing it 50 times with a cotton swab. △: After rubbing the painted surface with a cotton swab 50 times, the color transferred to the cotton swab, and the rubbed area became slightly faded. ×: After rubbing the painted surface with a cotton swab 50 times, much of the paint peeled off in the rubbed area.

[0103] D-3. Retort resistance After treating the printed materials obtained in each example and comparative example at 120°C / 30min in a retort tester, The printed surface was rubbed with a dry cotton swab, and its retort resistance was evaluated according to the following evaluation criteria. ◎: The painted surface remained completely unsmudged even after being rubbed 100 times with a cotton swab. ○: The painted surface remained completely unsmudged even after rubbing it 50 times with a cotton swab. △: After rubbing the painted surface with a cotton swab 50 times, the color transferred to the cotton swab, and the rubbed area became slightly faded. ×: After rubbing the painted surface with a cotton swab 50 times, much of the paint peeled off in the rubbed area.

[0104] [Table 3]

[0105] [Table 4]

[0106] [Table 5]

[0107] As shown in Comparative Example 1 of Table 5, a PET film was used as a printing substrate, and a primer was applied. - When the composition was not dried, the image quality deteriorated even when printing with the inkjet ink composition on top of it. Also, as shown in Comparative Example 2 of Table 5, when the coating film of the inkjet ink composition was not dried, the various coating film resistances were poor even after heat treatment by steam treatment.

[0108] As shown in Comparative Example 3 of Table 5, a PET film was used as a printing substrate, and a primer was applied. - When the composition was dried and the inkjet ink film was dried, some degree of dry friction resistance was obtained without heat treatment (Evaluation △), but the moisture friction resistance and retort resistance were insufficient (Evaluation ×). Furthermore, as shown in Comparative Examples 4 and 5 of Table 5, when the applied primer composition was dried and the inkjet ink film was dried, and then heat treatment was performed by oven treatment, some degree of dry friction resistance was obtained, similar to Comparative Example 3. While dry abrasion resistance was achieved (rated △), wet abrasion resistance and retort resistance were insufficient (rated ×).

[0109] In contrast, as shown in Examples 1 to 6 of Table 3, PET film is used as a printing substrate. When the applied primer composition was dried, the inkjet ink film was dried, and then steam treatment was performed, it was found that the various coating performances improved dramatically (all evaluations except for the moisture friction resistance evaluation in Example 2 were marked as ○). As shown in Example 2, when the drying temperature for drying the inkjet ink film was somewhat low (70°C), the evaluation of moisture friction resistance decreased slightly, suggesting that it is preferable to thoroughly dry the inkjet ink film. Furthermore, it was suggested that contact with water vapor at 70°C or higher for about 1 second is sufficient for steam treatment.

[0110] Furthermore, as shown in Examples 7 and 8 of Table 3, PET film was used as a printing substrate, and coating Even when the primer composition was dried, the inkjet ink film was dried, and then subjected to a hot water immersion treatment, the performance of various coatings was significantly improved. As shown in Example 8, when the water temperature for the hot water immersion treatment was somewhat low (80°C), the evaluation of the moisture resistance of the coating decreased slightly, suggesting that a higher hot water temperature is preferable.

[0111] As shown in Examples 9-11 of Table 3, it can be seen that even when the printing substrate was an aluminum plate, coated cardboard, or corrugated cardboard, the performance of various coatings was significantly improved by manufacturing inkjet printed materials under the same conditions as in Example 1. Specifically, in the case of aluminum plates, dry abrasion resistance, moisture abrasion resistance, and retort resistance all received a "○" rating. In the case of coated cardboard, although retort resistance could not be obtained because the substrate is paper, both dry abrasion resistance and moisture abrasion resistance received a "○" rating. In the case of corrugated cardboard, dry abrasion resistance received a "○" rating, and moisture abrasion resistance received a "△" rating.

[0112] As shown in Example 12 of Table 4, even when the binder resin of the primer composition was changed (from acrylic resin emulsion to vinyl acetate emulsion), the various coating film performances were significantly improved, similar to Example 1. As shown in Examples 13 to 16 of Table 4, even when the pigment of the inkjet ink composition was changed, the various coating film performances were significantly improved, similar to Example 1. As shown in Example 17 of Table 4, when wax was not added to the inkjet ink composition, the various coating film performances were significantly improved, but on the other hand, the evaluation of dry friction resistance was slightly reduced (evaluation △).

[0113] Furthermore, as shown in Examples 18-22 of Table 4, even when the aqueous resin emulsion of the inkjet ink composition was changed, the various coating film performances were significantly improved, similar to Example 1. In particular, as shown in Examples 18 and 19, when an acrylic-styrene resin emulsion was used, all coating film performances were evaluated as excellent (◎). On the other hand, when emulsions of acrylic-vinyl acetate resin, acrylic-vinyl chloride resin, or vinyl acetate resin were used (Examples 20-22), the various coating film performances were slightly reduced (evaluation △). Also, as shown in Comparative Example 6 of Table 5, an acrylic-vinyl acetate resin emulsion with a glass transition temperature (Tg) of -32°C... When using Lujon, the moisture resistance, friction resistance, and retort resistance were insufficient (evaluation: ×). [Industrial applicability]

[0114] The present invention provides a method for manufacturing inkjet printed materials that significantly improves the coating durability of the printed layer using an aqueous inkjet ink composition compared to conventional methods, thereby suppressing peeling and fading of the printed layer. Therefore, the applications of aqueous inkjet ink compositions can be greatly expanded, and for example, the present invention can be applied to the production of surface-printed packaging containers.

Claims

1. A primer application step involves applying an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt to a substrate and drying it to create a primer-coated product. An inkjet printing step is performed by printing an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment having a glass transition temperature (Tg) of -20 to 50°C onto the primer-coated material using an inkjet printing apparatus, and then drying it to produce an inkjet printed material. A heat treatment step is performed on the aforementioned inkjet printed material while exposing it to moisture, A method for manufacturing an inkjet printed material that includes the following in order.

2. The method for manufacturing an inkjet printed article according to claim 1, wherein the heat treatment is steam treatment or hot water immersion treatment.

3. The method for producing an inkjet printed article according to claim 1 or 2, wherein the binder resin contained in the aqueous primer composition contains an acrylic resin and / or a vinyl acetate resin.

4. The method for producing an inkjet printed material according to claim 1 or 2, wherein the water-soluble polyvalent metal salt contained in the aqueous primer composition contains a calcium salt.

5. The method for producing an inkjet printed article according to claim 1 or 2, wherein the aqueous resin emulsion contained in the aqueous inkjet ink composition contains a styrene-acrylic resin.

6. A method for producing an inkjet printed article according to claim 1 or 2, wherein the glass transition temperature (Tg) of the aqueous resin emulsion contained in the aqueous inkjet ink composition is 9 to 50°C.

7. The method for manufacturing an inkjet printed article according to claim 1 or 2, wherein the substrate is a resin film, metal, or corrugated cardboard.

8. The method for manufacturing an inkjet printed material according to claim 1 or 2, wherein the inkjet printed material is a surface-printed material.

9. An inkjet printing apparatus comprising a primer application means, an inkjet printing means, and a heat treatment means: The primer application means applies an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt to a substrate and dries it to provide a primer-coated product; The inkjet printing means prints an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment having a glass transition temperature (Tg) of -20 to 50°C onto the primer coating, dries it, and provides an inkjet printed material; The heat treatment means is an inkjet printing apparatus that performs heat treatment on the inkjet printed material while exposing it to moisture.

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