Aqueous ink and laminate

Abstract

To provide an aqueous ink from which a film excellent in adhesion, blocking resistance between films, wet friction resistance, and alcohol resistance can be obtained, and to provide a laminate using the same.SOLUTION: The aqueous ink contains a binder resin, a curing agent, and an aqueous solvent. The binder resin contains a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble type water-soluble resin. The laminate includes a substrate and a printing layer provided on the substrate. The printing layer is a printing layer of the aqueous ink.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-based ink and a laminate. [Background technology]

[0002] Gravure inks and flexographic inks are widely used to impart beauty and functionality to printed flexible packaging films.

[0003] Specifically, for example, when packaging products, these gravure inks and flexographic inks are printed on the front side (the side that does not come into contact with the product being packaged) of the base plastic film for decoration and surface protection, and printed materials with a simple configuration (called surface printing method) are used in which the back side (the side that comes into contact with the product being packaged) is not printed.

[0004] Furthermore, in the case of labels wrapped around the body of PET bottles or shrink labels, a top coat varnish is generally printed on the outer surface to provide scratch protection for the film, and a decorative printing layer and a varnish layer to provide blocking protection for the PET bottle are provided on the inner surface. The ink and top coat varnish used in the surface printing described above are directly exposed to the outside and come into direct contact with other components, and therefore require film properties that are strong enough to withstand handling of the product, etc. Furthermore, the quality of the printed design on the decorative printing layer of the flexible packaging film has a significant impact on the quality of the contents, so high image reproducibility is required to accommodate sophisticated designs that emphasize aesthetic appeal.

[0005] In recent years, based on the perspective of sustainability against the backdrop of worsening air pollution by VOCs, global warming, and other global issues, and in addition to considerations of occupational safety and health, flammability, and explosiveness, and in response to the movement to shift away from petroleum resources, so-called water-based inks in which organic solvents in inks are replaced with water are expected to become more widespread. Under these circumstances, various studies are being conducted on water-based inks that can also be used as inks for surface printing and top coat varnishes (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 07441356 Summary of the Invention [Problem to be solved by the invention]

[0007] Here, in addition to adhesion to the substrate, various physical properties (blocking resistance between films, alcohol resistance, water abrasion resistance, etc.) are required for the ink film, and therefore improvements that can satisfy all of these requirements are required for water-based inks. Furthermore, because decorative printing layers contain pigments, it is difficult to achieve excellent printability in addition to various film properties. For example, when applying a white printing layer to a transparent film, a white printing layer with sufficient white density has traditionally been achieved by printing with white ink twice. However, this method not only increases the time required for printing twice, but also requires the use of two printing units for the white ink, making it difficult to add special colors and limiting the reproducible color gamut. To ensure sufficient white density with a single printing pass, the concentration of the white pigment in the ink must be increased, but increasing the pigment concentration can lead to a deterioration in various film properties.

[0008] Therefore, an object of the present invention is to provide a water-based ink that can provide a film that has excellent adhesion, resistance to blocking between films, resistance to water friction, and resistance to alcohol. Another object of the present invention is to provide a laminate having an ink layer as a film that has excellent adhesion, resistance to blocking between films, resistance to water friction, and resistance to alcohol. [Means for solving the problem]

[0009] That is, the present invention relates to an aqueous ink containing a binder resin, a curing agent, and an aqueous solvent, wherein the binder resin contains a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble water-soluble resin.

[0010] The present invention also relates to a laminate comprising a substrate and a printed layer provided on the substrate, the printed layer containing a binder resin, a curing agent, and an aqueous solvent, the binder resin being a printed layer of an aqueous ink containing a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble water-soluble resin. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a water-based ink that can give a film that has excellent adhesion, resistance to blocking between films, resistance to water friction, and resistance to alcohol. Furthermore, according to the present invention, it is possible to provide a laminate having a water-based ink layer as a coating, which can provide a coating that has excellent adhesion, resistance to blocking between coatings, resistance to water friction, and resistance to alcohol. The aqueous ink of the present invention can provide a film that is excellent in adhesion, resistance to blocking between films, resistance to water friction, and resistance to alcohol, even when the ink has a high pigment concentration. Therefore, the aqueous ink of the present invention and a laminate comprising the aqueous ink layer of the present invention as a film can provide an ink layer with excellent aesthetic properties in a single printing run. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail an embodiment of the present invention (hereinafter sometimes referred to as the "present embodiment"); however, the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist.

[0013] (Water-based ink) The water-based ink of the present invention contains a binder resin, a curing agent, and an aqueous solvent, and the binder resin is characterized by containing a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble water-soluble resin. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0014] <Binder resin> The water-based ink of the present invention contains a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble water-soluble resin as binder resins.

[0015] (Self-crosslinking (meth)acrylic resin emulsion) The self-crosslinking (meth)acrylic resin emulsion used in the present invention may be a publicly known and available self-crosslinking (meth)acrylic resin emulsion. The self-crosslinking (meth)acrylic resin emulsion may be a single type or a combination of two or more types.

[0016] The (meth)acrylic resin contained in the self-crosslinking (meth)acrylic resin emulsion is not particularly limited, and examples thereof include homopolymers or copolymers of (meth)acrylates and copolymers of vinyl monomers copolymerizable with (meth)acrylates. Furthermore, copolymers having an acid value are preferred for the purpose of imparting water dispersibility and water solubility. Specific examples of resins having structural units derived from (meth)acrylic acid ester monomers include acrylic resins, styrene-acrylic resins, polyester-acrylic resins, urethane-acrylic resins, vinyl chloride-vinyl acetate copolymer-acrylic resins, silicone-acrylic resins, acrylamide resins, and epoxy-acrylic resins. In other words, a (meth)acrylic resin refers to a resin obtained by (co)polymerizing a (meth)acrylic acid ester as an essential monomer together with other polymerizable unsaturated group-containing compounds as needed.

[0017] Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, and perfluoro (meth)acrylate. Examples of the (meth)acrylate include cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, (meth)acrylamide, N-monoalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, acrolein, diacetone (meth)acrylamide, and acetoacetoxyethyl (meth)acrylate. The (meth)acrylate may be used alone or in combination of two or more.

[0018] Examples of the polymerizable unsaturated group-containing compound include vinyl monomers such as vinyl acetate, vinyl propionate, vinyl versatate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, (meth)acrylonitrile, styrene, α-methylstyrene, divinylstyrene, isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, and N-vinylpyrrolidone. The polymerizable unsaturated group-containing compound may be used alone or in combination of two or more.

[0019] Furthermore, for the purpose of introducing one or more acidic groups selected from the group consisting of carboxyl groups and carboxylate groups in which the carboxyl group has been neutralized with a basic compound, a copolymer having an acid value can be obtained by copolymerizing a (meth)acrylic monomer having a carboxyl group, such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, β-(meth)acryloyloxyethyl hydrogen succinate, or β-(meth)acryloyloxyethyl hydrogen phthalate. When an acidic group is introduced, it is preferable to appropriately adjust the amount of the monomer so that the acid value falls within a desired range, as will be described in detail later.

[0020] The self-crosslinking (meth)acrylic resin emulsion contains a self-crosslinking component, such as an isocyanate compound, an epoxy compound, an amine compound, a melamine compound, an aziridine compound, a hydrazine compound, an aldehyde compound, or an oxazoline compound. Among these, a hydrazine compound is preferred, and an example of the hydrazine compound is adipic acid dihydrazide. The content of the self-crosslinking component is preferably 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the acrylic emulsion solution in order to improve the storage stability of the self-crosslinking (meth)acrylic resin emulsion, and more preferably 0.3 parts by mass or more and 3 parts by mass or less. Furthermore, (meth)acrylic resins contain functional groups that react with the self-crosslinking component. Therefore, they must be produced by incorporating a polymerizable unsaturated monomer that reacts with the self-crosslinking component. Examples of such polymerizable unsaturated monomers include radically polymerizable unsaturated monomers containing a carbonyl group, such as diacetone (meth)acrylamide, diacetone (meth)acrylate, acetonyl (meth)acrylate, vinyl alkyl ketones, acrolein, formyl styrene, (meth)acrylic acid, and alkanal (meth)acrylates; radically polymerizable unsaturated monomers containing a carboxyl group; and radically polymerizable unsaturated monomers containing a hydroxyl group. Among these, diacetone (meth)acrylamide and diacetone (meth)acrylate are preferred. The self-crosslinking (meth)acrylic resin emulsion may contain, for example, both carbonyl and amine functional groups, and therefore has a self-reactive function that allows these to react with each other.

[0021] The self-crosslinking (meth)acrylic resin emulsion may preferably be a core-shell emulsion. The core-shell emulsion refers to a state in which a first polymer is dispersed in an aqueous medium by a second polymer. Typically, the second polymer is present at the outermost part of the resin particles to form the shell portion, and part or all of the first polymer forms the core portion. The polymer forming the shell portion is hydrophilic, while the polymer forming the core portion is hydrophobic. The hydrophilic shell portion maintains dispersion, while the hydrophobic core portion provides a reactive site for crosslinking. Therefore, it is preferable that the polymer forming the core portion contains a functional group that reacts with the self-crosslinking component.

[0022] (Meth)acrylic resins can be produced, for example, by polymerizing various monomers in the presence of a polymerization initiator at a temperature range of 50°C to 180°C, more preferably 80°C to 150°C. Examples of polymerization methods include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Furthermore, when the (meth)acrylic resin is a copolymer, it may be a random copolymer, block copolymer, graft copolymer, or the like, depending on the polymerization mode. When obtained by the bulk polymerization or solution polymerization method, the (meth)acrylic resin having an acidic group introduced therein can be neutralized with a neutralizing agent such as an alkali after polymerization, and the solvent can be replaced with an aqueous medium to form an aqueous emulsion.

[0023] The glass transition temperature (Tg) of the self-crosslinking (meth)acrylic resin emulsion is preferably in the range of -30°C to 60°C, more preferably -10°C to 50°C.

[0024] In the present invention, the glass transition temperature (Tg) refers to the so-called calculated glass transition temperature, which is a value calculated by the following method. (Formula 1) 1 / Tg(K)=(W1 / T1)+(W2 / T2)+...(Wn / Tn) (Equation 2) Tg(°C)=Tg(K)-273 In Equation 1, W1, W2, ..., Wn represent the mass percentage of each monomer relative to the total mass of the monomers used in producing the polymer, and T1, T2, ..., Tn represent the glass transition temperature (K) of the homopolymer of each monomer. The values ​​of T1, T2, ..., Tn are those listed in the Polymer Handbook (Fourth Edition, edited by J. Brandrup, E.H. Immergut, and E.A. Grulke). For the homopolymers of monomers whose glass transition temperatures are not listed in the Polymer Handbook, the glass transition temperatures were measured using a differential scanning calorimeter "DSCQ-100" (manufactured by TA Instrument) according to JIS K7121. Specifically, the polymer was vacuum-suctioned to completely remove the solvent, and the heat change was measured in the range of -100°C to +200°C at a temperature increase rate of 20°C / min. The glass transition temperature was determined as the point where a line equidistant in the vertical direction from the extended line of each baseline intersected with the curve of the stepwise change portion of the glass transition.

[0025] The acid value (also referred to as "AV") of the self-crosslinking (meth)acrylic resin emulsion is preferably 0 mgKOH / g to 100 mgKOH / g. This range is preferable because it allows the effects of the present invention to be maximized. The acid value of the (meth)acrylic resin (A) is more preferably 15 mgKOH / g or more, and more preferably 60 mgKOH / g or less, and even more preferably 40 mgKOH / g or less. In the present invention, the acid value refers to the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of resin.

[0026] In the present invention, the self-crosslinking (meth)acrylic resin emulsion is preferably an acrylic resin (i.e., a resin obtained by polymerizing substantially only (meth)acrylic acid ester monomers) or a styrene-acrylic resin (i.e., a resin obtained by copolymerizing a styrene monomer and a (meth)acrylic acid ester monomer) from the viewpoint of improving adhesion to the substrate and strength of the coating, and is more preferably a styrene-acrylic resin.

[0027] (alkali-soluble water-soluble resin) The alkali-soluble water-soluble resin used in the present invention is not particularly limited, and any publicly available alkali-soluble water-soluble resin can be used. Among them, it is preferable to use a (meth)acrylic resin from the viewpoint of compatibility with the self-crosslinking (meth)acrylic resin emulsion. The (meth)acrylic resin can be the same resin as that used in the aqueous (meth)acrylic emulsion. The alkali-soluble water-soluble resin may be used alone or in combination of two or more kinds. The aqueous ink of the present invention contains an alkali-soluble water-soluble resin, which improves the ink's stability over time and the pigment dispersibility of inks containing large amounts of pigment.Furthermore, the ink is also easily washable from a printing machine using a synthetic detergent after printing.

[0028] In the present invention, the alkali-soluble water-soluble resin is preferably an acrylic resin (i.e., a resin obtained by polymerizing substantially only (meth)acrylic acid ester monomers) or a styrene-acrylic resin (i.e., a resin obtained by copolymerizing a styrene monomer and a (meth)acrylic acid ester monomer), and more preferably a styrene-acrylic resin.

[0029] In the present invention, the (meth)acrylic resin, which is an alkali-soluble water-soluble resin, may be reacted with a self-crosslinking component. That is, the (meth)acrylic resin may be a self-crosslinking type. Examples of the self-crosslinking component include an isocyanate compound, an epoxy compound, an amine compound, a melamine compound, a hydrazine compound, an aldehyde compound, and an oxazoline compound. However, from the viewpoint of improving the ink stability over time, the ink washability, and the pigment dispersibility, it is preferable that the alkali-soluble water-soluble resin is a resin that is not a self-crosslinking type.

[0030] The glass transition temperature (Tg) of the alkali-soluble water-soluble resin is preferably in the range of 10°C to 140°C from the viewpoint of improving the substrate adhesion, blocking resistance, and water abrasion resistance. In particular, the glass transition temperature (Tg) is more preferably 20°C or higher, even more preferably 30°C or higher, and even more preferably 50°C or higher, and is more preferably 130°C or lower, even more preferably 120°C or lower, and even more preferably 100°C or lower.

[0031] The acid value of the alkali-soluble water-soluble resin is preferably 40 mgKOH / g to 250 mgKOH. This range is preferable from the viewpoint of improving pigment dispersibility, ink washability, and water abrasion resistance. In particular, the acid value is more preferably 60 mgKOH / g or more, even more preferably 100 mgKOH / g or more, and even more preferably 150 mgKOH / g or more, and more preferably 250 mgKOH / g or less, and even more preferably 230 mgKOH / g or less.

[0032] (mass ratio) In the present invention, the mass ratio of the nonvolatile components of the self-crosslinking (meth)acrylic resin emulsion to the alkali-soluble water-soluble resin is preferably self-crosslinking (meth)acrylic resin emulsion / alkali-soluble water-soluble resin = 10 / 90 to 90 / 10. By setting the mass ratio within this range, pigment dispersibility, ink washability, water abrasion resistance, etc. can be maximized. The mass ratio is more preferably in the range of 20 / 80 to 85 / 15, and most preferably in the range of 30 / 70 to 80 / 20.

[0033] In the present invention, the binder resin may contain a resin other than the self-crosslinking (meth)acrylic resin emulsion and the alkali-soluble water-soluble resin. However, from the viewpoint of more effectively improving the effects of the present invention, the proportion of the self-crosslinking (meth)acrylic resin emulsion and the alkali-soluble water-soluble resin in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and also preferably 100% by mass (i.e., the binder resin consists only of the self-crosslinking (meth)acrylic resin emulsion and the alkali-soluble water-soluble resin).

[0034] <Curing agent> The water-based ink of the present invention contains a curing agent. The water-based ink of the present invention contains a self-crosslinking (meth)acrylic resin emulsion, and therefore has excellent adhesion to substrates and excellent film strength. However, by containing a curing agent, the effects of the present invention can be further improved. As the curing agent, known curing agents can be used, and it is preferable to use a crosslinking agent capable of reacting with a carboxy group in the binder resin. Among them, at least one crosslinking agent selected from the group consisting of epoxy-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, chelate-based curing agents such as titanium chelate, and isocyanate-based crosslinking agents that can be incorporated into aqueous inks is preferred, and an aziridine-based curing agent is more preferred. The content of the curing agent (solid content) in the ink is preferably 0.05 to 10 mass % based on the total amount of the ink, and more preferably 0.3 to 5 mass %.

[0035] (Aziridine curing agent) The aziridine curing agent is a compound having an aziridine group, and more specific examples thereof include trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-(2-methylaziridine)propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), and N,N'-toluene-2,4-bis(1-aziridinecarboxamide). The aziridine curing agent may be used alone or in combination of two or more.

[0036] Commercially available aziridine curing agents can be used, such as "PZ-33" manufactured by Nippon Shokubai Co., Ltd., "DZ-22E" manufactured by Nippon Shokubai Co., Ltd., "XL-706" manufactured by Stahl, and "SU-125F" manufactured by Meisei Chemical Industry Co., Ltd.

[0037] In the water-based ink of the present invention, the amount of the non-volatile content of the aziridine curing agent relative to 100 parts by mass of the non-volatile content of the binder resin is preferably 1.0 part by mass or more and 35.0 parts by mass or less, and preferably 2.0 parts by mass or more, more preferably 3.0 parts by mass or more, and preferably 30.0 parts by mass or less, more preferably 25.0 parts by mass or less, relative to 100 parts by mass of the non-volatile content of the binder resin.

[0038] In addition, when used to prepare water-based inks, binder resins and aziridine-based curing agents are often dispersed in a solvent. Therefore, in order to calculate the mass ratio of the nonvolatile content mentioned above, it is important to know the NV value (Nonvolatile Content) of each binder resin and aziridine-based curing agent. The "non-volatile content" (NV) is also generally referred to as the "solid content."

[0039] (water-based solvent) The aqueous solvent used in this embodiment may be water alone or an organic solvent miscible with water. Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and n-propyl alcohol; polyhydric alcohols such as propylene glycol and glycerin; and ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and ethyl carbitol. The aqueous solvent may be used alone or in combination of two or more.

[0040] (pigment) The water-based ink of the present invention can contain various pigments in addition to those mentioned above. Examples of pigments include inorganic pigments and organic pigments from the viewpoint of materials, and black pigments, indigo pigments, green pigments, red pigments, purple pigments, yellow pigments, orange pigments, brown pigments, etc. from the viewpoint of coloring. Water-based inks containing these pigments can be used as inks for so-called black-and-white printing or color printing. When used as a white ink, conventionally known white pigments can be used as the white pigment. Examples of white pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum. Among inorganic pigments, titanium oxide is particularly preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, alcohol resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide that has been treated with silica and / or alumina is preferred. The average particle size of the pigment is preferably in the range of 1 to 300 nm, and more preferably about 50 to 150 nm. The pigment is preferably contained in an amount sufficient to ensure the concentration and coloring power of the aqueous ink, i.e., 1 to 60 wt % relative to the total weight of the ink composition, or 10 to 90 wt % in terms of the solids weight ratio in the ink composition. In particular, the aqueous ink of the present invention, even in a composition containing 20 mass % or more of the pigment relative to the total weight of the ink composition, exhibits excellent pigment dispersibility, and the film obtained using the ink exhibits excellent adhesion, resistance to blocking between films, resistance to water abrasion, and resistance to alcohol. The aqueous ink of the present invention may contain 30 mass % or more of the pigment in the aqueous ink, 40 mass % or more, or even 50 mass %. Excellent effects can be obtained even with inks containing such high concentrations of pigment. The pigments can be used alone or in combination of two or more.

[0041] (surfactant) The aqueous ink of the present invention may further contain a surfactant in addition to the above. The surfactant is preferably an acetylene-based surfactant or an alcohol alkoxylate-based surfactant. These surfactants may be used alone or in combination of two or more.

[0042] Specific examples of acetylene surfactants include 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyne-3-ol, 3-methyl-1-butyne-3-ol, 3-methyl-1-pentyne-3-ol, 3-hexyne-2,5-diol, 2-butyne-1,4-diol, etc. These acetylene surfactants may be used alone or in combination of two or more.

[0043] Commercially available acetylene surfactants include commercially available alkylene oxide unmodified acetylene glycol surfactants and commercially available alkylene oxide modified acetylene glycol surfactants. Commercially available alkylene oxide unmodified acetylene glycol surfactants include Surfynol 61, 82, and 104 (all manufactured by Air Products Co., Ltd.). Commercially available alkylene oxide-modified acetylene glycol surfactants include Surfynol 420, 440, 465, 485, TG, 2502, Dynol 604, and 607 (all manufactured by Air Products Co., Ltd.); Surfynol SE, MD-20, Olfine E1004, E1010, PD-004, EXP4300, PD-501, PD-502, and SPC (all manufactured by Nissin Chemical Industry Co., Ltd.); and Acetylenol EH, E40, E60, E81, E100, and E200 (all manufactured by Kawaken Fine Chemicals Co., Ltd.). Among these, alkylene oxide-modified acetylene glycol surfactants are preferred as the acetylene surfactants.

[0044] Specific examples of the alcohol alkoxylate surfactant include alcohol ethoxylate and alcohol polyethoxylate. Commercially available alcohol alkoxylate surfactants include "BYK-DYNWET800" (manufactured by BYK). These alcohol alkoxylate surfactants may be used singly or in combination of two or more.

[0045] In addition to the surfactants mentioned above, acrylic polymer surfactants (e.g., "Polyflow WS-314" manufactured by Kyoeisha Chemical Co., Ltd.) and modified silicone surfactants (e.g., "Polyflow KL-401" manufactured by Kyoeisha Chemical Co., Ltd.) may also be used as needed.

[0046] When the aqueous ink of the present invention contains a surfactant, the total proportion of the surfactant in the total amount of the aqueous ink is preferably 0.1% by mass or more and 3.0% by mass or less. If the proportion is 0.1% by mass or more, the wettability of the substrate can be improved, and the effect of maintaining adhesion to the substrate can be obtained. Furthermore, if the proportion is 3.0% by mass or less, the abrasion resistance, water abrasion resistance, and scratch resistance can be maintained well. From the same viewpoint, the proportion is more preferably 1.0% by mass or less.

[0047] (wax) The water-based ink of the present invention may further contain a wax in addition to the above-mentioned components. The wax is preferably a hydrocarbon wax. Specific examples of the wax include liquid paraffin, natural paraffin, synthetic paraffin, microcrystalline wax, polyethylene wax, fluorocarbon wax, ethylene-propylene copolymer wax, tetrafluoroethylene resin wax, and Fischer-Tropsch wax. These waxes may be used alone or in combination of two or more. Among these, polyethylene wax is preferred as the wax.

[0048] When the water-based ink of the present invention contains wax, the total proportion of wax in the total amount of the water-based ink is preferably 0.5% by mass or more and 5.0% by mass or less. If the proportion is 0.5% by mass or more, the effect of maintaining water abrasion resistance can be obtained. Furthermore, if the proportion is 5.0% by mass or less, adhesion to the substrate, water abrasion resistance, and blocking resistance can be maintained well.

[0049] (Other ingredients) In addition to the above, the water-based ink of the present invention may contain appropriate amounts of other components, such as a general-purpose resin other than the above-mentioned binder resin, an extender pigment, a lubricant (oleic acid amide, stearic acid amide, erucic acid amide, etc.), a pigment dispersant, a leveling agent, an antifoaming agent (a silicone-based antifoaming agent, a non-silicone-based antifoaming agent, etc.), a plasticizer, an infrared absorbing agent, an ultraviolet absorbing agent, a fragrance, a flame retardant, etc., as needed.

[0050] (Water-based ink manufacturing method) The method for producing the aqueous ink of the present invention is not particularly limited, but for example, the aqueous ink can be obtained by dispersing a mixture to which an aqueous solvent and an antifoaming agent etc. have been added, and then adding a binder resin, an aqueous solvent, an aziridine-based curing agent, and, if necessary, additives such as a surfactant, and stirring and mixing. For the above dispersion and stirring and mixing, a dispersing machine such as a bead mill, Eiger mill, sand mill, gamma mill, or attritor, which is commonly used in the production of inks for flexographic printing or gravure printing, can be used.

[0051] Furthermore, the water-based ink of the present invention is preferably used for flexographic printing or gravure printing, as described below.

[0052] When the aqueous ink of the present invention is used for flexographic printing or gravure printing, i.e., when the aqueous ink of the present invention is used as a flexographic ink or gravure ink, its viscosity should be 7 to 25 seconds, more preferably 10 to 20 seconds, at 25°C using a Zahn Cup #4 (manufactured by Rigo Co., Ltd.). Furthermore, the surface tension of the ink at 25°C is preferably 25 to 50 mN / m. The lower the surface tension of the ink, the better the ink's wetting ability to substrates such as films. However, if the surface tension is below 25 mN / m, the ink tends to spread and connect adjacent dots in halftone dot areas. This can easily cause a stain on the printed surface known as dot bridging. On the other hand, if the surface tension exceeds 50 mN / m, the ink's wetting ability to substrates such as films decreases, which can easily cause cissing. From the same viewpoint, the surface tension of the ink at 25° C. is more preferably 33 mN / m or more, and more preferably 43 mN / m or less.

[0053] (Laminate) The laminate of the present invention comprises a substrate and an ink layer provided on the substrate, wherein the ink layer is a printed layer of the above-mentioned water-based ink. That is, the laminate of the present invention is obtained by printing the above-mentioned water-based ink on the substrate.

[0054] Examples of substrates include thermoplastic resin films, paper, synthetic paper, steel plates, aluminum foil, wood, woven fabrics, knitted fabrics, nonwoven fabrics, gypsum boards, and wooden boards. Among these, paper, synthetic paper, thermoplastic resin films, and the like are preferred as substrates. The substrate may also be a combination of multiple types of the above-mentioned materials, such as a laminated substrate in which paper and a thermoplastic resin film are laminated, or a laminated substrate in which a thermoplastic resin film and aluminum foil are laminated. In the case of a combination of multiple types, the lamination method is not particularly limited, and they may be bonded using a general-purpose one-component adhesive, two-component adhesive, or the like, or a laminated substrate in which multiple thermoplastic resin films are bonded by extrusion molding.

[0055] The thermoplastic resin film is not particularly limited, and examples thereof include films made of thermoplastic resins such as polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene phthalate (PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; biodegradable resins typified by polyhydroxycarboxylic acids such as polylactic acid, and aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate); polyolefin resins such as polypropylene (PP) and polyethylene; polyimide resins; polyarylate resins; and mixtures thereof, as well as laminate films made of multiple layers of these. Among these, films made of polyester, polyamide, polyethylene, and polypropylene are preferred as thermoplastic resin films.

[0056] These thermoplastic resin films may be unstretched or stretched films, and their manufacturing method is not particularly limited. The thickness of the thermoplastic resin film used as a substrate is not particularly limited, but is generally within the range of 1 to 500 μm. It is preferable that the surface of the thermoplastic resin film to be printed is subjected to a corona discharge treatment. This can further improve adhesion. Furthermore, silica, alumina, or the like may be vapor-deposited on the surface of the thermoplastic resin film to be printed, and a gas barrier coating layer such as an oxygen gas barrier layer may be laminated thereon.

[0057] To maximize the effects of the present invention, it is preferable to use a substrate that is a constituent material of the shrink label, and it is preferable to use a thermoplastic resin film that shrinks upon heat treatment. In particular, it is preferable to use a heat-shrinkable thermoplastic resin film (referred to as a "heat-shrinkable film") that has high mechanical and chemical strength and good printability. Examples of such heat-shrinkable films include oriented polyester films, shrinkable polyvinyl chloride films, shrinkable polystyrene films, shrinkable polyethylene terephthalate films, and shrinkable polypropylene films. The printing surface may be untreated or may be subjected to a surface treatment such as plasma treatment, corona treatment, radiation treatment, or silane coupling treatment. The thermoplastic resin film may have a single-layer structure or a multi-layer structure. Furthermore, the thermoplastic resin film may be subjected to aluminum vapor deposition or transparent vapor deposition.

[0058] In this embodiment, a printed matter is obtained by printing an aqueous ink onto a substrate and providing a printed layer. In this regard, the ink is typically applied to the substrate using a printing method such as gravure printing or flexographic printing, and then dried and fixed in an oven to obtain a printed layer. The drying temperature is typically about 40 to 60°C.

[0059] The thickness of the printed layer of the above-mentioned aqueous ink is not particularly limited, and can be determined appropriately taking into account various factors such as the drying properties of the ink when forming the printed layer and running costs.

[0060] The above-mentioned water-based ink printing layer is preferably formed using a printing method such as flexographic printing or gravure printing. Both flexographic printing and gravure printing are types of rotary printing, and can form a printing layer that maintains the five properties well. Flexographic printing and gravure printing are also preferred in terms of high-speed printing suitability, print reproducibility, etc.

[0061] Flexographic printing is a type of relief printing that mainly uses a rubber plate as the printing plate (relief plate) and a fine mesh engraved roll called an anilox roll to supply ink to the plate. The anilox roll receives ink from a chamber-type doctor and applies it to the printing plate, and has the advantage of being able to transfer ink evenly to the printing plate through the anilox roll.

[0062] Specifically, ink is applied to the surface of an anilox roll, which has partition walls and numerous openings surrounded by the partition walls, and a doctor is pressed against the surface of the anilox roll to scrape off the ink present on the top surfaces of the partition walls of the anilox roll and fill the recessed openings with ink. Next, a flexographic plate is pressed against the anilox roll to transfer the ink present in the recessed parts of the anilox roll to the raised parts (pattern parts) of the printing plate, and the plate is then brought into contact with a substrate to transfer the ink present in the pattern parts of the plate to the substrate, thereby obtaining a printed product.

[0063] Rotary printing methods may also be combined. For example, when rotary printing is performed using a thermoplastic resin film as the substrate, rotary printing is performed using water-based ink on the surface of a rolled thermoplastic resin film. After printing, processes such as lamination, slitting (cutting off unnecessary width portions), and bag making (cutting and heat sealing to make bags) can be performed. Rotary printing of water-based ink on a rolled thermoplastic resin film enables high-speed printing and is highly productive.

[0064] As mentioned above, rotary printing includes gravure printing and flexographic printing, and either method can be used. However, it is preferable to use flexographic printing for printing with the water-based ink of the present invention. Therefore, flexographic printing will be described in detail below. In this specification, rotary printing means gravure printing and flexographic printing, and does not include other printing methods such as ink jet printing and silk screen printing.

[0065] In flexographic printing, water-based ink is supplied from a container to an anilox roller, which has an uneven surface, either directly or via an ink supply pump or the like. The water-based ink supplied to the anilox roller is transferred to the plate surface upon contact with the raised portions of the plate surface, and then finally transferred to the thermoplastic resin film upon contact between the plate surface and the thermoplastic resin film, forming a pattern and / or characters.

[0066] When using aqueous ink, the ink drying property is slightly inferior to that of solvent-based flexographic printing ink, so it is preferable that the ink film thickness is as thin as possible. From this perspective, it is preferable that the amount of ink supplied to the Aronix roller is as small as possible. On the other hand, as a thinner film thickness tends to result in a thinner print density, it is preferable to appropriately control the pigment concentration of the aqueous ink used. Specifically, an appropriate print density can be obtained by increasing the pigment concentration of the aqueous ink by 1 to 5% by weight compared to the concentration of the solvent-based flexographic printing ink.

[0067] A rolled thermoplastic resin film is a thermoplastic resin film in a rolled form that is aligned to a specified width. It is a film for rotary printing, unlike pre-cut sheets. The width of the film is selected appropriately based on the plate width of the rotary printing press used and the width of the image (design) portion of the gravure plate. When using multiple colors of rotary printing ink to overlay colors, the order of printing is not particularly limited.

[0068] When performing surface printing, it is common to print white ink first, if necessary, and then print colored inks. When multiple colored inks are used, they can be printed in the following order, for example, yellow, magenta, cyan, and black, but this is not particularly limited. In the case of surface printing, the water-based ink of the present invention is applied as an overcoat to the printing surface of the rotary printed material.

[0069] When the color of the substrate is white, that is, when the substrate is a paper substrate or a thermoplastic resin film with a white pigment kneaded therein, printing with only colored ink is possible as needed.

[0070] Furthermore, when reverse printing is performed, it is common to first print color inks on a rolled thermoplastic resin film, followed by white ink. When multiple color inks are used, they can be printed in the order of, for example, black, cyan, magenta, and yellow, but this is not particularly limited. Large-format printing machines can also use special colors in addition to the basic colors. That is, large-format printing machines have multiple printing units corresponding to 5 to 10 colors, each equipped with one ink color, allowing for 5 to 10 colors to be printed simultaneously. The printed material obtained by reverse printing can be used as is, or an anchor coating agent and adhesive can be applied to the printed surface of the obtained rotary printed material, and after drying, the resulting product can be laminated with a film or the like to form a laminate.

[0071] The ink layer (printed layer) in the laminate of the present invention has strong film properties that can withstand external contact and excellent blocking resistance and water-rubbing resistance, so it can be used as the outermost layer. In this case, the laminate of the present invention may further include an intermediate ink layer between the substrate and the ink layer. Such an intermediate ink layer can be a printed layer of any ink, and may consist of only one layer or two or more layers. The intermediate ink layer may also be a colored ink layer that appropriately contains coloring materials such as pigments based on the desired design. The ink layer (printed layer) in the laminate of the present invention is also preferably used as a colored ink layer because it has excellent pigment dispersibility, adhesion, blocking resistance, and film properties, even when containing a pigment. In particular, by using it as a white ink layer containing a high concentration of pigment, an ink layer with excellent aesthetic properties can be obtained with a single printing run. The method for producing the intermediate ink layer is not particularly limited; for example, it can be produced in the same manner as the printed layer of the water-based ink of the present invention described above.

[0072] The laminate of the present invention has excellent adhesion to any type of substrate, including plastic films, and in addition to the physical properties described in the examples, it also has excellent coating film strength, particularly abrasion resistance and scratch resistance, and is therefore suitable for use in configurations in which the printed layer is the outermost layer. Therefore, in front-printed or back-printed printed matters, printed matters having a printed layer of the water-based ink of the present invention on the surface that will be the outermost layer during distribution are preferred, as they can maximize the effects of the present invention. The laminate of the present invention can be used in a variety of applications, such as plastic labels (such as shrink labels and wrap-around labels) for use on beverage or food bottles, integrated packaging, exterior packaging, etc. In particular, the laminate of the present invention is suitably used as a heat-shrinkable film in the various applications described above. [Example]

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0074] [Self-crosslinking (meth)acrylic resin emulsion Resin A] A reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser was charged with 60.0 parts by mass of n-propyl acetate. The mixture was heated to 90°C while stirring under a nitrogen atmosphere. Meanwhile, 57.0 parts by mass of methyl methacrylate, 10.0 parts by mass of n-butyl methacrylate, 13.0 parts by mass of n-butyl acrylate, 20.0 parts by mass of methacrylic acid, and 1.0 part by mass of azobisisobutyronitrile were dissolved in 40.0 parts by mass of n-propyl acetate and added dropwise using a dropping funnel over 4 hours. After the addition was completed, the reaction was continued for an additional 6 hours. After the reaction was completed, the mixture was cooled, and the resulting acrylic resin solution was neutralized by adding 8.0 parts by mass of 30% aqueous ammonia. Ion-exchanged water was then added and the mixture was heated to perform solvent substitution, yielding an aqueous acrylic resin solution with a solids content of 55%. The resin had an acid value of 130 mgKOH / g and a Tg of 83°C. Next, 32.1 parts by weight of the above acrylic resin aqueous solution was placed in a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and 160.0 parts by weight of ion-exchanged water was added. The mixture was heated to 75°C while stirring under a nitrogen atmosphere. Next, using the dropping funnel, 33.0 parts by weight of methyl methacrylate, 31.0 parts by weight of n-butyl methacrylate, 32.0 parts by weight of n-butyl acrylate, 4.0 parts by weight of diacetone acrylamide, and 3.5 parts by weight of 30% ammonium persulfate were added dropwise over 4 hours. After completion of the addition, the reaction was continued for an additional 6 hours. Subsequently, 3 parts by weight of adipic acid dihydrazide (ADH) was added to the resulting acrylic emulsion solution to obtain a self-crosslinking (meth)acrylic resin emulsion (Resin A) with a solids content of 40%. Resin A had an acid value of 20 mgKOH / g and a Tg of 33°C.

[0075] [Acrylic resin emulsion Resin EM] A reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser was charged with 60.0 parts by mass of n-propyl acetate. The mixture was heated to 90°C while stirring under a nitrogen atmosphere. Meanwhile, 10.0 parts by mass of methyl methacrylate, 59.0 parts by mass of styrene, 5.0 parts by mass of 2-ethylhexyl acrylate, 26.0 parts by mass of acrylic acid, and 1.0 part by mass of azobisisobutyronitrile were dissolved in 40.0 parts by mass of n-propyl acetate and added dropwise using a dropping funnel over 4 hours. After the addition was completed, the reaction was continued for an additional 6 hours. After the reaction was completed, the mixture was cooled, and the resulting acrylic resin solution was neutralized by adding 8.0 parts by mass of 30% aqueous ammonia. Ion-exchanged water was then added and the mixture was heated to perform solvent substitution, yielding an aqueous acrylic resin solution with a solids content of 55%. The resin had an acid value of 202 mgKOH / g and a Tg of 94°C. Next, 182.8 parts by weight of the above acrylic resin aqueous solution was charged into a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and 220.0 parts by weight of ion-exchanged water was added. The temperature was raised to 75°C while stirring under a nitrogen atmosphere. Next, using the dropping funnel, 10.0 parts by weight of methyl methacrylate, 41.0 parts by weight of styrene, 49.0 parts by weight of 2-ethylhexyl acrylate, and 3.5 parts by weight of 30% ammonium persulfate were added dropwise over 4 hours. After the addition was completed, the reaction was continued for an additional 6 hours, yielding an acrylic resin emulsion (Resin EM) with a solids content of 40%. Resin EM had an acid value of 101 mgKOH / g and a Tg of 52°C.

[0076] [Alkali-soluble water-soluble resin Resin a] A reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser was charged with 80.0 parts by mass of methyl triglycol. The mixture was heated to 90°C while stirring under a nitrogen atmosphere. Next, using two dropping funnels, 46.0 parts of styrene, 5.0 parts of methyl methacrylate, 20.0 parts of n-butyl methacrylate, and 29.0 parts of methacrylic acid were added dropwise from one funnel over 4 hours. From the other funnel, 5.0 parts of azobisisobutyronitrile was dissolved in 10.0 parts of methyl isobutyl ketone and added dropwise over 4.5 hours. After the addition, the reaction was continued for another 4 hours. After the reaction was completed, the mixture was cooled, and 55 parts of the resulting acrylic resin solution was neutralized by adding 10.0 parts by mass of 30% ammonia water. Ion-exchanged water was then added and the mixture was heated to perform solvent substitution, yielding a water-soluble acrylic resin with a solids content of 30%. Resin A had an acid value of 189 mgKOH / g and a Tg of 94°C.

[0077] [Alkali-soluble water-soluble resin Resin b] The alkali-soluble water-soluble resin (resin b) was prepared by the same procedure as in the preparation of the alkali-soluble water-soluble resin (resin a) described above, but with the conditions appropriately changed so that the acid value was 215 mg KOH / g, the Tg was 110°C, and the solid content was 30%.

[0078] [Alkali-soluble water-soluble resin Resin c] The alkali-soluble water-soluble resin (resin c) was prepared by the same procedure as in the preparation of the alkali-soluble water-soluble resin (resin a) described above, but with appropriate changes to the conditions so that the acid value was 241 mgKOH / g, the Tg was 104°C, and the solid content was 30%.

[0079] [Preparation of Water-Based Ink and Laminate] In each example, a water-based ink was prepared according to the formulation shown in the table in a conventional manner. On the other hand, a corona-treated polystyrene heat-shrinkable film (Bonset BS55S, 50 μm thick, manufactured by Takiron C.I. Co., Ltd.) was prepared as the substrate, and a Flexoproof100 test printing machine (200 lines / inch anilox, manufactured by Testing Machines, Inc.) was prepared as the printing device. Then, using the anilox roll and resin plate of this test printing machine, a 240 mm x 80 mm solid image was printed with each example of aqueous ink at a printing speed of 100 m / min. The resulting print was then aged at 25°C for 24 hours to obtain a printed ink laminate.

[0080] The resulting laminate was evaluated as follows.

[0081] (pigment dispersibility) The ink was adjusted to a liquid temperature of 25°C on the day after preparation, and the viscosity was measured using a Zahn cup #4 for evaluation. Within 5:20 seconds 4:20 seconds - within 30 seconds Within 3:30 seconds-40 seconds Within 2:40-50 seconds 1:50 seconds or more

[0082] (Adhesion to substrate) Cellophane tape was applied to the surface of the laminate on which the ink layer was formed. The cellophane tape was then quickly peeled off, and the degree of peeling of the ink layer (film) from the substrate was visually observed and evaluated according to the following criteria. A rating of 4.5 was given when, among multiple evaluations, ratings of 4 and 5 were mixed at the same level. A practical level is 4 or higher. 5: No peeling of the ink layer 4: The area of ​​the ink layer peeling is more than 0% but less than 10% of the printed area 3: The area of ​​the ink layer peeling is 10% or more but less than 30% of the printed area 2: The area of ​​the ink layer peeling is 30% or more but less than 75% of the printed area 1: The ink layer peels off over 75% of the printed area

[0083] (blocking resistance) The printed surface of the laminate is combined with the printed surface and the applied pressure is 5kg / cm 2 The test piece was left to stand for one day at 40°C and 80% humidity under a load of 1000 kJ / cm2. The test piece was then peeled off by hand, and the presence or absence of peel resistance and the degree of transfer of the ink layer (film) were visually observed and evaluated according to the following criteria. 5: No ink layer transfer, no peeling resistance 4: No ink layer transfer, but peel resistance 3: The ink layer transfer amount is less than 10% of the printing area, and there is peeling resistance 2: The amount of ink layer transferred is 10% or more but less than 50% of the printing area, and there is peeling resistance. 1: The ink layer transfers to 50% or more of the printing area and has peel resistance

[0084] (alcohol resistant) A 50 μm drop of ethanol was applied to the printed surface as an evaluation solution, and after drying at room temperature for 24 hours, the coating film was washed with water at room temperature and the degree of peeling and whitening of the coating film was evaluated. 5: No change in appearance 4: Slight whitening 3: Whitening present 2: Slight ink detachment 1: Ink detachment occurs

[0085] (Water friction resistance) A water-soaked Kanakin was placed on the ink layer surface of the laminate, and rubbed 100 times with a load of 200 g using a Gakushin-type rub fastness tester. The degree of peeling of the ink layer (film) was then visually observed and evaluated according to the following criteria. 5: No peeling of the ink layer 4: The area of ​​the ink layer peeling is more than 0% but less than 10% of the printed area 3: The area of ​​the ink layer peeling is 10% or more but less than 50% of the printed area 2: The area of ​​the ink layer that has peeled off is 50% or more but less than 70% of the printed area 1: The ink layer peels off over 70% of the printed area

[0086] (white density) The white density of the prints was evaluated using a transmission densitometer. 5:0.2 or higher 4:0.16 or higher 3:0.12 or higher 2:0.1 or more 1:0.1 or less

[0087] (Ink washability) Thirty minutes after the ink was applied, a synthetic detergent was applied to the coating, and the peeled area of ​​the coating was evaluated when the coating was wiped with a cloth. 5: Peeling area 100% 4: Peeling area less than 50-100% 3: Peeling area less than 10-50% 2: Peeling area less than 1-10% 1: No peeling

[0088] The results are shown in Tables 1 to 3. In the tables, the numbers in the "blending" column represent the mass % of the solid content other than the solvent.

[0089] [Table 1]

[0090] [Table 2]

[0091] [Table 3]

[0092] Details of each component other than the resin in the table are as follows: Solvent: Ion-exchanged water Surfactant: alkylene oxide-modified acetylene glycol surfactant (Surfynol 420, manufactured by Nissin Chemical Industry Co., Ltd.) Color pigment: Titanium oxide, manufactured by Teika Corporation "TITANIX JR-701" Wax: Polyethylene wax (Chemipearl W-400, manufactured by Mitsui Chemicals, Inc.) Antifoaming agent: Silicone emulsion (TEGO Foamex 1488 manufactured by Evonik) Silicone additive: Silicone emulsion (TEGO Glide 490 manufactured by Evonik) Aziridine compound: Aziridine-based curing agent ("PZ-33" manufactured by Nippon Shokubai Co., Ltd., NV value: 100% by mass) Epoxy: Epoxy hardener (Nagase ChemteX EX-614B) Isocyanate: Isocyanate curing agent (Mitsui Chemicals Takenate WD-726) Carbodiimide: Carbodiimide curing agent (Nisshinbo Carbodilite E-02) Titanium chelate: Titanium chelate curing agent (TC-300 manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0093] From the tables, it can be seen that the examples according to the present invention have good evaluation results in all of the substrate adhesion, blocking resistance, alcohol resistance, and water friction resistance, and are excellent in various durability properties in addition to adhesion to the substrate. Furthermore, it exhibits excellent pigment dispersibility even in inks containing high concentrations of pigment, and in addition to excellent adhesion to the substrate, it also has excellent durability in various respects.

Claims

1. An aqueous ink comprising a binder resin, a curing agent, and an aqueous solvent, wherein the binder resin comprises a self-crosslinking (meth)acrylic resin emulsion and an alkali-soluble water-soluble resin.

2. 2. The water-based ink according to claim 1, wherein the curing agent is an aziridine-based curing agent.

3. 3. The water-based ink according to claim 1, wherein at least one of the self-crosslinking (meth)acrylic resin emulsion and the alkali-soluble water-soluble resin contains a styrene-acrylic resin.

4. 3. The water-based ink according to claim 1, wherein the mass ratio of the non-volatile components of the self-crosslinking (meth)acrylic resin emulsion to the alkali-soluble water-soluble resin is self-crosslinking (meth)acrylic resin emulsion / alkali-soluble water-soluble resin=10 / 90 to 90 / 10.

5. 3. The water-based ink according to claim 1, wherein the alkali-soluble water-soluble resin has an acid value of 40 mgKOH / g to 250 mgKOH / g and a glass transition temperature (Tg) of 10 to 140°C.

6. 3. The water-based ink according to claim 1, wherein the acid value of the self-crosslinking (meth)acrylic resin emulsion is 0 mgKOH / g to 100 mgKOH / g.

7. The water-based ink according to claim 1 or 2, further comprising a pigment.

8. 8. The water-based ink according to claim 7, wherein the pigment is titanium oxide, and the content of the water-based ink is 30% by mass or more.

9. 3. The water-based ink according to claim 1, which is used for flexographic printing or gravure printing.

10. A laminate comprising a substrate and a printed layer provided on the substrate, the printed layer being a printed layer of the water-based ink according to claim 1 or 2.

11. The laminate according to claim 10, further comprising a varnish layer on the printed layer.

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