Inkjet print manufacturing method

Abstract

To improve the coating resistance of a layer printed with a water-based inkjet ink in an inkjet printed matter. [Solution] The method for producing an inkjet printed matter includes, in order: 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 produce a primer-coated matter; an inkjet printing step in which an aqueous inkjet ink composition containing an aqueous resin emulsion and a pigment and having a glass transition temperature (Tg) of -20 to 50°C is printed on the primer-coated matter using an inkjet device, and dried to produce an inkjet printed matter; and a heat treatment step in which the inkjet printed matter is heat-treated while being exposed to moisture.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an inkjet printed matter using a water-based inkjet ink. [Background technology]

[0002] Inkjet inks are used to form printed layers by ejecting and depositing small ink droplets onto various recording media, and are broadly classified into aqueous inks, solvent-based inks, curable inks, etc. Aqueous inkjet inks are primarily composed of water and have the advantage of being environmentally friendly.

[0003] On the other hand, aqueous inkjet inks may not be sufficient in terms of the resistance of their coating films, for example, hardness and strength such as dry rub resistance, moisture resistance and water resistance such as wet rub resistance and retort resistance. Therefore, printed matter printed with aqueous inkjet inks is 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 printed with aqueous inkjet ink is used as a packaging container, so-called reverse printing is generally performed with the aqueous inkjet ink, and the packaging container is often made without exposing the printed surface to the outside.

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

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-196177 [Patent Document 2] Japanese Patent Application Publication No. 2018-203905 Summary of the Invention [Problem to be solved by the invention]

[0006]

[0006] As described above, the printed layer of an inkjet-printed matter printed with an aqueous inkjet ink has low coating resistance and is prone to wear due to friction, or the coating may peel off due to exposure to humidity or moisture. For this reason, attempts have been made to improve the physical properties of the inkjet-printed matter by applying a primer before printing with an aqueous inkjet ink, but this has not been able to sufficiently improve the coating physical properties of the printed layer itself of the printed matter. Therefore, an object of the present invention is to improve the coating resistance of the printed layer of a matter printed with an aqueous inkjet ink. [Means for solving the problem]

[0007] That is, a first aspect of the present invention relates to a method for producing an inkjet printed matter, which will be described below. [1] A method for producing an inkjet printed product, the method comprising the steps of: a primer application step of applying an aqueous primer composition containing a binder resin and a water-soluble polyvalent metal salt to a substrate and drying the applied composition to produce a primer-coated product; 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 product using an inkjet printing device and drying the printed material to produce an inkjet printed product; and a heat treatment step of heat-treating the inkjet printed product while exposing it to moisture.

[0008] The present invention preferably relates to the following method for producing an inkjet printed matter. [2] The method for producing an inkjet printed matter according to [1] above, wherein the heat treatment is a steam treatment or a hot water immersion treatment. [3] The method for producing an inkjet printed matter according to [1] or [2] above, 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 matter according to any one of [1] to [3] above, 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 matter according to any one of [1] to [4] above, wherein the aqueous resin emulsion contained in the aqueous inkjet ink composition contains a styrene-acrylic resin. [6] The method for producing an inkjet printed matter according to any one of [1] to [5] above, 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 producing an inkjet printed matter according to any one of [1] to [6] above, wherein the substrate is a resin film, metal, or cardboard. [8] The method for producing an inkjet printed matter according to any one of [1] to [7] above, wherein the inkjet printed matter is a surface-printed printed matter.

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

[0010] According to the present invention, it is possible to improve the resistance of various coating films in the ink-printed layer of an ink-jet printed material using an aqueous ink-jet ink. Therefore, according to the present invention, an ink-jet printed material using an aqueous ink-jet ink can be used as a surface-printed material or the like, with the printed surface in contact with the outside. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an outline of an inkjet printing apparatus according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Manufacturing method for inkjet printed materials The method for producing an inkjet printed matter of the present invention includes, 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 producing an inkjet printed matter of the present invention is a step that includes applying an aqueous primer composition to a substrate to be printed and drying it.

[0014] 1-1-1. Printing substrate Examples of the printing substrate in the method for producing an inkjet printed matter of the present invention include, but are not limited to, plastic substrates such as polyethylene terephthalate (PET) film, polypropylene film, and polyvinyl chloride sheet; metal substrates such as aluminum; corrugated paper; coated paper such as art paper, inkjet paper, and inkjet glossy paper; uncoated paper such as plain paper and offset paper; and fabrics such as cotton. Preferably, the printing substrate is sometimes the substrate for a packaging container; examples include plastic film, metal, and corrugated board.

[0015] 1-1-2. Water-based primer composition The aqueous primer composition used in the primer application 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 is present as an emulsion or 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., but acrylic resins and / or vinyl acetate resins are preferred.

[0017] The content of the binder resin in the aqueous primer composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. By including a binder resin, the adhesion of the aqueous primer composition to the substrate to be printed is improved, but if the content of the binder resin is excessively high, the storage stability of the aqueous primer composition may be reduced.

[0018] The acrylic resins include, as monomers, unsaturated carboxylic acids such as (meth)acrylic acid and (anhydrous) maleic acid; (meth)acrylic acid esters having an aliphatic hydrocarbon group 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)acrylate. The acrylic resins are resins obtained by polymerizing (meth)acrylic acid ester compounds having a hydroxyalkyl group such as 2-hydroxypropyl acrylate and 3-hydroxypropyl (meth)acrylate; (meth)acrylamide, acrylonitrile, olefin-based compounds; styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, dimethylstyrene, ethylstyrene, isopropylstyrene, t-butylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, fluorostyrene, and styrene; benzyl (meth)acrylate-based monomers such as benzyl (meth)acrylate; phenyl (meth)acrylate-based monomers such as phenyl (meth)acrylate, etc. These acrylic resins may be used alone or in combination of two or more.

[0019] The acrylic resin preferably has a glass transition temperature (Tg) of -30 to 120°C, a weight average molecular weight of 3,000 to 50,000, and an acid value of 30 to 500 mgKOH / g.

[0020] Vinyl acetate resins are resins containing 50 mol% or more of vinyl acetate monomer. Examples of vinyl acetate resins include vinyl acetate homopolymers and copolymers of vinyl acetate with 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; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, fumaric acid, and crotonic acid, as well as their anhydrides.

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

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

[0023] The chlorination degree (chlorine content) of the chlorinated polyolefin is preferably 1 to 40 mass % and more preferably 10 to 30 mass % based on the total mass of the resin. If the chlorination degree of the chlorinated polyolefin is too high, the polarity of the resin itself becomes excessively high, and when the resin is contained in a primer composition, the adhesion to the printing substrate may decrease.

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

[0026] The polyvalent metal salt of an organic acid is, for example, a polyvalent metal salt of a fatty acid. - In the formula, the number of carbon atoms in R is preferably 1 or more and 30 or less. Specific examples of fatty acids include acetic acid, propionic acid, octylic acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, 12-hydroxystearic 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 - In the formula, the number of carbon atoms in R is more preferably 1 to 10, and even more preferably 1 to 5. Examples of such fatty acids include acetic acid.

[0027] The polyvalent metal salt of an inorganic acid may be, for example, a polyvalent metal salt of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc., and may preferably be a polyvalent metal salt of hydrochloric acid or nitric acid. Specific preferred examples of the polyvalent metal salt of an inorganic acid 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 printed layer of the aqueous inkjet ink composition formed thereon can be laminated more closely.

[0029] The method for producing an inkjet printed matter of the present invention includes a heat treatment step (steam treatment or hot water immersion treatment), and the heat treatment step may cause the water-soluble polyvalent metal salt contained in the primer layer to change in quality (for example, by reacting with the aqueous resin emulsion in the aqueous inkjet ink composition) and become 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; examples include compounds represented by the following general formula A, compounds represented by the following general formula B, maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide, and two or more of these may be used in combination. Among these, adipic acid dihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide are more preferred. (chemical 1) General formula A JPEG2026043710000002.jpg23170 (in General Formula A, n represents 1 to 10) General formula B JPEG2026043710000003.jpg16170 (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, more preferably 5% by mass or less. The hydrazine derivative can improve adhesion to the printing substrate, but if the amount is excessive, the storage stability of the primer composition may decrease.

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

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

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

[0035] The applied primer composition is dried to form a primer layer. There are no particular limitations on the drying method, but drying by heating is preferred. The heating temperature is about 30 to 80°C, and in some cases, about 40 to 70°C is preferred. The drying time varies depending on the heating temperature, but is about 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 on the primer-coated product obtained by the primer coating step, and then dried to produce an inkjet printed product.

[0037] 1-2-1. Aqueous inkjet ink composition The aqueous inkjet ink composition contains an aqueous resin emulsion, a pigment, and water, and may contain other components such as wax, a surfactant, a water-soluble organic solvent, a pigment dispersant, etc. The water content in the aqueous inkjet ink composition is preferably 10% by mass or more, and 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 contained 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, and polyethylene resin emulsions. 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. Depending on the composition of the aqueous resin emulsion, the physical properties (such as abrasion resistance and moisture resistance) of the inkjet printing layer of the resulting inkjet printed matter can be improved.

[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 a (meth)acrylic acid alkyl ester. Furthermore, a monomer such as acrylamide or acrylonitrile may be copolymerized as a comonomer within a range that does not impair the effects of the styrene-acrylic resin emulsion. Specific examples of commercially available styrene-acrylic resins include Yodozole AD199, Neocryl A-1092, and Neocryl A-655.

[0040] The glass transition temperature (Tg) of the aqueous resin emulsion is −20° C. or higher, preferably −10° C. or higher, more preferably 0° C. or higher, and even more preferably 9° C. or higher; on the other hand, it is 50° C. or lower, preferably 40° C. or lower. When the glass transition temperature (Tg) of the aqueous resin emulsion is 50° C. or lower, the film-forming properties of the ink composition on the primer-coated surface are easily improved; on the other hand, when it is −20° C. or higher, the ejection stability of the ink composition is easily improved, and the physical properties (such as abrasion resistance and moisture resistance) of the inkjet printed layer of the inkjet-printed material obtained after the heat treatment step can be improved.

[0041] The glass transition temperature (Tg) of the aqueous resin emulsion may be a theoretical glass transition temperature or an actually measured glass transition temperature. For example, when the aqueous resin emulsion is an acrylic resin or a styrene-acrylic resin, the theoretical glass transition temperature Tg is calculated by the following Wood's equation. Wood's formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 + + W X / Tg X [In the formula, Tg1~Tg X are the glass transition temperatures of the homopolymers of the monomers 1, 2, 3, x that make up the anionic group-containing resin, and W1 to W X are the polymerization fractions of the monomers 1, 2, 3, and x, respectively, and Tg is the theoretical glass transition temperature. The glass transition temperature in Wood's equation is expressed in absolute temperature.

[0042] The actual glass transition temperature can be measured by thermal analysis, which is performed in accordance with JIS K7121 (Method for measuring transition temperature of plastics), for example, using a Pyris1 DSC manufactured by PerkinElmer, under conditions of a temperature rise rate of 20°C / min and a nitrogen gas flow rate of 20 ml / min.

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

[0044] The content of the aqueous resin emulsion in the aqueous inkjet ink composition is preferably 1% by mass or more, more preferably 2% by mass or more, in terms of resin solids; on the other hand, it is preferably 10% by mass or less, more preferably 8% by mass or less. If the content of the aqueous resin emulsion is 1% by mass or more, in terms of resin solids, the appearance and various resistances of the resulting printed matter can be improved; on the other hand, if it is 10% by mass or less, the inkjet ejection of the ink composition can be stabilized.

[0045] 1-2-1B. Pigments The pigment contained in the aqueous inkjet ink composition may be any known inorganic pigment or organic pigment that has been conventionally used.

[0046] Examples of inorganic pigments include carbon black, titanium oxide, zinc oxide, lithopone, 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, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, Prussian blue, cobalt blue, cerulean blue, manganese violet, cobalt violet, mica, and the like.

[0047] Examples of the organic pigment include azo-based, azomethine-based, polyazo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, indigo-based, thioindigo-based, quinophthalone-based, benzimidazolone-based, isoindoline-based, and isoindolinone-based organic pigments.

[0048] Examples of organic pigments are listed 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 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; etc. These pigments can be used alone or in combination of two or more.

[0049] The pigment content of the aqueous inkjet ink compositions other than the white ink is preferably 1% by mass or more, and more preferably 2% by mass or more, and is preferably 10% by mass or less, and more preferably 7% by mass or less. The pigment content of the white ink is preferably 5 to 15% by mass, based on the total amount of the aqueous inkjet ink compositions. By ensuring that the pigment content is at a certain level or more, it is easy to obtain sufficient coloring power, while by ensuring that the pigment content is at a certain level or less, it is easy to prevent an increase in the viscosity of the ink composition and ensure the fluidity of the ink.

[0050] 1-2-1C. Wax The aqueous inkjet ink composition may contain a 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, and microcrystalline wax, which may be used alone or in combination of two or more. The wax is more preferably polyethylene wax and / or Fischer-Tropsch wax, and even more preferably polyethylene wax.

[0051] Specific examples of polyethylene waxes include AQUACER 507, AQUACER 515, AQUACER 531, AQUACER 539 (all manufactured by BYK Japan), Hitec E-6314 (35% solids, nonionic emulsified polyethylene wax, manufactured by Toho Chemical Industry Co., Ltd.), Hitec E-1000 (35% solids, nonionic emulsified polyethylene wax, manufactured by Toho Chemical Industry Co., Ltd.), etc. These may be used alone or in combination of two or more.

[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, and is preferably 7% by mass or less, more preferably 5% by mass or less. Wax can improve the blocking resistance and rub resistance (especially dry rub resistance) of printed matter.

[0053] 1-2-1D.Surfactants The aqueous inkjet ink composition may contain a surfactant. Examples of surfactants include acetylenic diol surfactants, silicone surfactants, fluorine-based surfactants, alcohol ethoxylate surfactants, and alcohol alkoxylate surfactants; however, acetylenic diol surfactants may be preferred. The acetylenic diol surfactant can improve the solid filling of the printed (recorded) image using the aqueous inkjet ink composition.

[0054] Specific examples of acetylene diol surfactants include Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104BC, Surfynol 104DPM, Surfynol 104PA, Surfynol 104PG-50, Surfynol 420, and Surfynol 440, all manufactured by Evonik Corporation; and Olfine E1004, Olfine E1010, Olfine E1020, Olfine PD-001, Olfine PD-002W, Olfine PD-004, Olfine PD-005, Olfine EXP.4001, Olfine EXP.4200, Olfine EXP.4123, and Olfine EXP.4300, all manufactured by Nissin Chemical Industry Co., Ltd. These surfactants may be used alone or in combination of two or more.

[0055] The content of surfactant in the aqueous inkjet ink composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more; and 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 producing an inkjet printed matter of the present invention, the white aqueous inkjet ink composition may be used as whitening printing. Whitening printing refers to concealing the color of the base (substrate) by printing with a white ink before printing an aqueous inkjet ink composition other than the white ink. In this case, the surface tension of the white aqueous inkjet ink composition and the surface tension of the aqueous inkjet ink composition other than the white ink can be adjusted with a surfactant to make it easier to overcoat printed layers of the aqueous inkjet ink composition other than the white ink.

[0057] 1-2-1E. Water-soluble organic solvents The aqueous inkjet ink composition may contain a water-soluble organic solvent. Examples of the water-soluble organic solvent 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; tetraethylene glycol, polyethylene glycol, tetrapropylene glycol, thiazolinone ... Examples of water-soluble organic solvents include glycerin, monoalkyl esters, monoalkyl ethers, and dialkyl ethers of these alcohols; 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 solvent contained in the aqueous inkjet ink composition may be one or more types alone, or two or more types may be combined.

[0058] The content of the water-soluble organic solvent in the aqueous inkjet ink composition is preferably 20% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. The total content of the water-soluble organic solvent and water in the aqueous inkjet ink composition is preferably 40% by mass or more, and more preferably 50% by mass or more, and is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0059] 1-2-1F. Pigment dispersants The aqueous inkjet ink composition may contain a pigment dispersant. The pigment dispersant is preferably a resin-type pigment dispersant (pigment dispersing resin). The pigment dispersing resin has a hydrophobic group (e.g., styrene or a long-chain alkyl group) in the molecule, and the hydrophobic group imparts affinity to the pigment. Examples of pigment dispersing 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 or styrene-acrylic resins such as styrene-lauroyl acrylate-acrylic acid copolymers.

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

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

[0062] 1-2-2. Printing and drying of aqueous inkjet ink composition The aqueous inkjet ink composition is printed onto a primer-coated substrate using an inkjet printing device and dried to form a printed layer, thereby producing an inkjet print. In the inkjet printing process, only a single-color aqueous inkjet ink composition may be printed, or multiple colors of aqueous inkjet ink compositions may be printed (color printing). In addition, in the inkjet printing process, a white aqueous inkjet ink composition may be printed (referred to as white printing), and then other colors of aqueous inkjet ink compositions may be overcoated and printed.

[0063] The type of inkjet printing device that can be used is not particularly limited, and 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 further added to adjust the electrical conductivity of the ink composition.

[0064] The aqueous 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 a substrate to be printed. The ink composition is ejected from the printer head onto the substrate (printing an image) so that the film thickness on the substrate after drying is, for example, 1 to 60 μm.

[0065] When droplets of the aqueous inkjet ink composition of the present invention land on a substrate, the water-soluble polyvalent metal salt contained in the primer layer interacts with the binder resin contained in the aqueous inkjet ink composition (for example, by forming an ionic bond), which can prevent the droplets of the aqueous inkjet ink composition from excessively wetting and spreading on the substrate.

[0066] The aqueous inkjet ink composition printed on the substrate is dried to form a printed layer. The drying method is not particularly limited, but can be heat drying. The drying temperature can be about 60°C to 130°C, and in some cases it is preferable to set it in the range of 80°C to 120°C. The drying time depends on the drying temperature, but can be about 1 to 10 minutes, or can be 5 minutes or less.

[0067] 1-3.Heat treatment process The inkjet printed matter obtained by the inkjet printing process is subjected to a heat treatment, specifically, a heat treatment while being 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 contacting the printed surface of an inkjet printed material with water vapor. The temperature of the water vapor brought into contact with the printed material (the temperature of the water vapor when it comes into contact with the printed material) is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, and may be 100°C. The steam treatment may also be pressurized water vapor treatment, and the steam temperature may exceed 100°C. The treatment time for the steam treatment may be 0.1 seconds or longer and 10 seconds or shorter.

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

[0070] 1-3-2. Hot water immersion treatment Hot water immersion treatment refers to immersing an inkjet printed matter 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 0.1 to 10 seconds or less.

[0071] Heat treating an inkjet-printed matter by steam treatment, hot water immersion treatment, or other means improves the coating film properties of the printed layer in the inkjet-printed matter. Improved coating film properties include abrasion resistance in a dry state (dry abrasion resistance), abrasion resistance in a wet state (wet abrasion resistance), and abrasion resistance when exposed to hot air at 100°C or higher, such as in a retort test (retort resistance).

[0072] The reason why heat treatment while exposing to moisture improves the coating film properties of the printed layer in an inkjet printed matter is not particularly limited, but it is thought that the water-soluble metal salt contained in the primer layer and the aqueous pigment dispersion resin and aqueous resin emulsion contained in the printed layer of the aqueous inkjet ink composition are crosslinked and cured by the heat treatment, and become more insoluble in water, although the reason is not limited to this.

[0073] It has been difficult to obtain sufficient coating physical properties from a printed layer obtained by printing a conventional aqueous inkjet ink composition. In the present invention, a printing substrate is treated with a specific primer composition, and a printed layer of the aqueous inkjet ink composition is subjected to a specific heat treatment, thereby achieving a dramatic improvement in coating physical properties.

[0074] 2. Uses of inkjet printed materials The inkjet printed matter of the present invention may be a surface-printed matter. That is, the printed layer formed by the inkjet ink may be disposed on the outer surface. The inkjet printed matter of the present invention is resistant to deterioration even when disposed on the outer surface because the printed layer (the coating film of the primer composition and the printed layer formed by the inkjet ink) has high physical resistance (such as abrasion resistance).

[0075] The inkjet printed matter of the present invention may be a surface-printed packaging container, such as a plastic film container, a cardboard container, an aluminum pouch container, or an aluminum can. The plastic film container or aluminum pouch container may be used as a retort packaging container. The printed layer of the inkjet printed matter of the present invention can maintain its abrasion resistance even after retort treatment (exposure to 100°C or higher), and therefore can also be preferably used as a retort packaging container.

[0076] The inkjet printed matter of the present invention may have an overcoat varnish that covers the printed layer of the inkjet ink, or may be a laminate in which a laminate film is laminated on the printed surface of the inkjet ink.

[0077] 3. Inkjet printing devices The inkjet printing apparatus of the present invention is an apparatus capable of carrying out the above-described method for producing an inkjet printed product. Preferably, the inkjet printing apparatus can carry out the above-described process for producing an inkjet printed product inline, but is not limited to this. In other words, the primer application step, inkjet printing step, and heat treatment step may be carried out in a single apparatus, or may be carried out in different apparatuses.

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

[0079] The primer application means 20 may be any means for applying the aqueous primer composition to the printing substrate 1, and preferably includes a coating device 21 such as a bar coater, blade coater, air knife coater, roll coater, gravure coater, rod blade coater, lip coater, curtain coater, or die coater. The primer application means 20 also preferably includes drying means 22 for drying the primer composition applied to the printing substrate 1. The drying means 22 may be, for example, a heating oven, a hot air dryer, or a heated fixing roller.

[0080] The inkjet printing means 30 is a means for printing the aqueous inkjet ink composition described above onto the printing substrate 1, and includes at least an inkjet recording head 31. The inkjet printing means 30 may include one inkjet recording head 31, in which case only a single color (e.g., black) ink composition can be printed; or it may include multiple (e.g., five) inkjet recording heads (31A-31E), in which case multiple colors (e.g., white, black, yellow, magenta, and cyan) of ink compositions can be printed (color printing). Whiteout printing can also be performed using a white aqueous inkjet ink composition.

[0081] There are no particular limitations on the type of inkjet recording head 31, and it may be of a piezo type, a bubble jet type, etc. The nozzle of the inkjet recording head may be a single nozzle, but is preferably a multi-nozzle head.

[0082] The inkjet printing means 30 preferably includes drying means 32 for drying the printed inkjet ink. The drying means 32 may be provided corresponding to each inkjet recording head 31, or may be one that collectively dries the inkjet inks printed by a plurality of inkjet recording heads 31 (A to E), as shown in Fig. 1. The drying means 32 may be, for example, a heating oven, a hot air dryer, a heated fixing roller, or the like.

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

[0084] The transport means 10 may be any means that transports the printing substrate 1 to the primer application means 20, the inkjet printing means 30, and the heat treatment means 40 in that order. For example, as shown in Fig. 1, it may be composed of rollers 11. The inkjet printing apparatus 100 may also have a take-up device (not shown) for taking up the inkjet-printed material. [Example]

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

[0086] A. Preparation of Primer Composition Primer compositions P1 and P2 were prepared according to the compositions shown in Table 1. Specifically, calcium acetate, an aqueous resin emulsion, a chlorinated polyolefin, and a surfactant were dissolved in water. The values ​​in Table 1 are in parts by mass. [Table 1] Acrylic emulsion: Vinyblan 2687 (acrylic, manufactured by Nissin Chemical Industry Co., Ltd.) Vinyl acetate emulsion: Vinyblan 1002 (vinyl acetate type, manufactured by Nissin Chemical Industry Co., Ltd.) Chlorinated polyolefin (chlorination degree 21%): Superchlorine E-604 (chlorination degree 21%, manufactured by Nippon Paper Industries Co., Ltd.) Surfactant: Olfine E1010 (acetylene diol, manufactured by Nissin Chemical Industry Co., Ltd.)

[0087] B. Preparation of Aqueous Inkjet Ink Composition B-1. Preparation of water-based resin varnish 20 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 solids content of 20%.

[0088] B-2. Preparation of ink base B-2-Bk. Preparation of water-based black ink base 23.7 parts by mass of the aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for pigment dispersion. 12 parts by mass of carbon black (trade 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 an aqueous black ink base.

[0089] B-2-Y. Preparation of Water-Based Yellow Ink 23.7 parts by mass of the aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for pigment dispersion. 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 an aqueous yellow ink base.

[0090] B-2-M. Preparation of Water-Based Magenta Ink 23.7 parts by mass of the aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for pigment dispersion. 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.

[0091] B-2-C. Preparation of water-based cyan ink base 23.7 parts by mass of the aqueous resin varnish was mixed with 64.3 parts by mass of water to prepare a resin varnish for pigment dispersion. 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.

[0092] B-2-W. Preparation of Water-Based White Ink 40.0 parts by mass of the aqueous resin varnish was mixed with 20.0 parts by mass of water to prepare a resin varnish for pigment dispersion. 40 parts by mass of titanium oxide (product name R-960, manufactured by DuPont) was further added to this varnish, stirred and mixed, and then milled in a wet circulation mill to prepare an aqueous white ink base.

[0093] B-3. ​​Preparation of aqueous inkjet ink Water-based inkjet inks were prepared with the compositions of Examples 1 to 12 shown in Table 2. The materials used in the preparation are listed below. <Water-based resin emulsion> Acrylic-styrene (Tg-14℃): Yodosol AD199, acrylic-styrene emulsion, manufactured by Henkel Acrylic-styrene (Tg 9°C): Neocryl A-1092, acrylic-styrene emulsion, manufactured by DSM Neoresins Acrylic-styrene (Tg 33°C): Neocryl 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°C): Vinyblan 1245L, acrylic-vinyl acetate emulsion, manufactured by Nissin Chemical Co., Ltd. Acrylic-vinyl chloride (Tg 33°C): Vinyblan 278L, acrylic-vinyl chloride emulsion, manufactured by Nissin Chemical Co., Ltd. Vinyl acetate (Tg 30°C): Vinybran GV6181, vinyl acetate emulsion, manufactured by Nissin Chemical Co., Ltd. <Wax emulsion> AQUACER 539 (35% solids, manufactured by BYK) <Surfactant> Olfine E1010 (100% solids, HLB 13-14, manufactured by Nissin Chemical Co., Ltd.) Olfine E1004 (100% solids, HLB 7-9, manufactured by Nissin Chemical Co., Ltd.)

[0094] Aqueous inkjet ink compositions of Examples 1 to 12 were prepared with the compositions shown in Table 2. 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. Inkjet Printing The following steps (C-1 to C-3) were carried out under the conditions shown in Tables 3 to 5 to produce inkjet printed materials of Examples and Comparative Examples.

[0097] C-1. Primer application process The primer composition (P1 or P2) was applied to a PET film (E5100, 12 μm, manufactured by Toyobo), an aluminum plate (0.3 mm thick), coated cardboard (OK ball, 230 g / m, manufactured by Oji Materia), or cardboard base paper (K ​​liner, 170 g / m, manufactured by Oji Materia) using a bar coater with a wire diameter of 0.1 mm, and then heated and dried in an oven at 50°C for 5 seconds to form a primer coating film. However, in Comparative Example 1 (Table 5), the primer coating film was not dried.

[0098] C-2. Inkjet printing process The aqueous inkjet ink compositions (Examples 1 to 12) were filled into cartridges for an Epson PX105 printer, and printing was carried out on the primer coating film formed in C-1 above, followed by heating and drying for 3 minutes in an oven at 70°C or 100°C to form an ink coating film. However, in Comparative Examples 1 and 2 (Table 5), the ink coating film was not dried.

[0099] C-3. Heat treatment process <Steam Treatment> The ink coating film formed in C-2 above was subjected to a steam treatment by spraying steam using a steam cleaner so that the temperature of the steam contacting the ink coating film was 70° C., 100° C., or 120° C. (Specifically, the distance between the coating film surface and the steam nozzle was adjusted.) 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 water at 80°C for 1 second or 2 seconds. <Oven Treatment> The ink coating film 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 printed matter obtained in each example or comparative example was evaluated for the following 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 print obtained in each Example and Comparative Example was rubbed with a dry cotton swab, and the dry rub resistance was evaluated according to the following evaluation criteria. ◎: No smearing at all even after rubbing the coating surface with a cotton swab 200 times ○: No smearing at all after rubbing the coating surface with a cotton swab 100 times △: After rubbing the coating surface with a cotton swab 100 times, the color transferred to the cotton swab and the rubbed area was slightly faded. ×: After rubbing the coating surface with a cotton swab 100 times, most of the rubbed area peeled off.

[0102] D-2. Wet friction resistance The printed surface of the print obtained in each of the Examples and Comparative Examples was rubbed with a cotton swab moistened with water, and the wet rub resistance was evaluated according to the following evaluation criteria. ◎: No smearing at all even after rubbing the coating surface with a cotton swab 100 times ○: No smearing at all even after rubbing the coating surface with a cotton swab 50 times △: After rubbing the coating surface with a cotton swab 50 times, the color transferred to the cotton swab and the rubbed area was slightly faded. ×: After rubbing the coating surface with a cotton swab 50 times, most of the rubbed area peeled off.

[0103] D-3. Retort resistance The printed matter obtained in each of the Examples and Comparative Examples was treated in a retort tester at 120°C for 30 minutes, and then the printed surface was rubbed with a dry cotton swab to evaluate the retort resistance according to the following evaluation criteria. ◎: No smearing at all even after rubbing the coating surface with a cotton swab 100 times ○: No smearing at all even after rubbing the coating surface with a cotton swab 50 times △: After rubbing the coating surface with a cotton swab 50 times, the color transferred to the cotton swab and the rubbed area was slightly faded. ×: After rubbing the coating surface with a cotton swab 50 times, most of the rubbed area peeled off.

[0104] [Table 3]

[0105] [Table 4]

[0106] [Table 5]

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

[0108] As shown in Comparative Example 3 in Table 5, when a PET film was used as a printing substrate, an applied primer composition was dried, and a coating film of an inkjet ink composition was dried, a certain degree of dry rub resistance was obtained without heat treatment (evaluation △), but the wet rub resistance and retort resistance were insufficient (evaluation ×). Furthermore, as shown in Comparative Examples 4 and 5 in Table 5, when an applied primer composition was dried, and a coating film of an inkjet ink composition was dried, and then heat treatment was performed in an oven, similar to Comparative Example 3, a certain degree of dry rub resistance was obtained (evaluation △), but the wet rub resistance and retort resistance were insufficient (evaluation ×).

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

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

[0111] As shown in Examples 9 to 11 in Table 3, even when the printing substrate was an aluminum plate, coated cardboard, or corrugated board, various coating film performances were significantly improved by producing inkjet printed matter under the same conditions as in Example 1. That is, in the case of aluminum plate, the dry rub resistance, wet rub resistance, and retort resistance were all rated as ◯. In the case of coated cardboard, since the substrate is paper, retort resistance is not obtained, but both the dry rub resistance and wet rub resistance were rated as ◯. In the case of corrugated board, the dry rub resistance was rated as ◯, and the wet rub resistance was rated as △.

[0112] As shown in Example 12 in Table 4, even when the binder resin of the primer composition was changed (changing from acrylic resin emulsion to vinyl acetate emulsion), various coating film performances were significantly improved, as in Example 1. As shown in Examples 13 to 16 in Table 4, even when the pigment of the inkjet ink composition was changed, various coating film performances were significantly improved, as in Example 1. As shown in Example 17 in Table 4, when no wax was blended into the inkjet ink composition, various coating film performances were significantly improved, but on the other hand, the dry rub resistance rating was slightly lower (rating △).

[0113] Furthermore, as shown in Examples 18 to 22 in Table 4, even when the aqueous resin emulsion of the inkjet ink composition was changed, various coating film performances were significantly improved, as in Example 1. In particular, when an acrylic-styrene resin emulsion was used, as in Examples 18 and 19, all coating film performances were evaluated as Excellent. On the other hand, when an acrylic-vinyl acetate resin, acrylic-vinyl chloride resin, or vinyl acetate resin emulsion was used (Examples 20 to 22), various coating film performances were slightly reduced (evaluated as Fair). Furthermore, as shown in Comparative Example 6 in Table 5, when an acrylic-vinyl acetate resin emulsion with a glass transition temperature (Tg) of -32°C was used, wet rub resistance and retort resistance were insufficient (evaluated as Bad). [Industrial Applicability]

[0114] According to the method for producing an inkjet printed matter of the present invention, the coating resistance of the printed layer of the aqueous inkjet ink composition can be significantly improved compared to conventional methods, and peeling, discoloration, etc. of the printed layer can be suppressed. Therefore, the applications of the aqueous inkjet ink composition can be greatly expanded, and the method for producing an inkjet printed matter of the present invention can be applied to, for example, the production of packaging containers with surface printing.

Claims

1. 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 the composition to form a primer coated product; an inkjet printing step of printing an aqueous inkjet ink composition containing an aqueous resin emulsion having a glass transition temperature (Tg) of −20 to 50° C. and a pigment onto the primer-coated material using an inkjet printing device, and drying the ink to produce an inkjet printed product; a heat treatment step of subjecting the inkjet printed matter to heat treatment while exposing it to moisture; A method for producing an inkjet printed matter, comprising the steps of:

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

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

6. The method for producing an inkjet printed matter according to claim 1 or 2, wherein the water-based resin emulsion contained in the water-based inkjet ink composition has a glass transition temperature (Tg) of 9 to 50°C.

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

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

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

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