Ink composition for wallpaper, laminate, and wallpaper

Abstract

To provide a wallpaper ink composition with excellent drying properties that can form a printed layer with excellent interlayer adhesion, leveling properties, and heat resistance; a laminate comprising a printed layer formed using the above wallpaper ink composition; and wallpaper comprising the above laminate. [Solution] A wallpaper ink composition comprising a (meth)acrylic resin emulsion (A), a polyurethane resin dispersion (B), a free neutralizing agent (C), a leveling agent, and an aqueous medium, wherein the polyurethane resin dispersion (B) is a polycarbonate-based polyurethane resin, the elongation at break of the polyurethane resin dispersion (B), measured in accordance with JIS K7161-1:2014, is 40 to 300%, and the mass ratio of the solids represented by the polyurethane resin dispersion (B) / (meth)acrylic resin emulsion (A) is 0.25 to 0.70.

Description

Technical Field

[0001] The present invention relates to an ink composition for wallpaper, a laminate, and wallpaper.

Background Art

[0002] Wallpaper used as an interior material for residences and the like is produced by laminating a plastic film such as a vinyl chloride resin or olefin resin on a base material such as paper or nonwoven fabric, and performing printing on the surface thereof to impart design properties. In recent years, designs of wallpaper have been diversified, and the importance of ink compositions using gravure printing and the like has been increasing in order to express high-definition patterns and deep textures.

[0003] Conventionally, as inks for wallpaper, those in which a synthetic resin is used as a binder, and a pigment and various additives are blended therewith are known. In the wallpaper production process, heat foaming treatment and embossing (stamping) are performed after printing, and thus the ink composition is required to have various properties capable of withstanding these severe processing conditions.

[0004] In addition, the leveling property of the printed layer is also one of the properties required for wallpaper inks. By improving the leveling property, the gradation of the gradient becomes smoother, and it becomes easier to realize the reproducibility of the intended pattern and a uniform and beautiful smooth surface. Furthermore, the drying property that affects the work efficiency on the production line is also an extremely important factor in maintaining product quality. Furthermore, high adhesion between printed layers is also required when the ink is applied in multiple layers.

[0005] Patent Document 1 discloses a water-based printing ink composition for wallpaper (ink for wallpaper) characterized by containing: an acrylic resin that exhibits water solubility in the presence of (A), obtained by copolymerizing a monomer mixture comprising an inorganic acid and / or an organic acid, (B) 7 to 50% by weight of a vinyl monomer having an amino group with a specific structure in the molecule, 1 to 30% by weight of a vinyl monomer having an acetyloxyacetoxy group in the molecule, and the balance being 20 to 92% of another copolymerizable vinyl monomer; (C) an acrylic resin emulsion; and (D) a crosslinking agent.

[0006] Patent Document 2 discloses an aqueous ink for wallpaper (wallpaper ink) containing a vinyl chloride resin emulsion of a polymer consisting of (A) a polycarbonate-based urethane oligomer having a number average molecular weight of 5,000 to 50,000 and (B) a monomer composition containing vinyl chloride monomers.

[0007] Patent Document 3 discloses an aqueous coating agent for wallpaper (wallpaper ink) characterized by comprising a water-soluble or water-dispersible polyurethane resin (A) having an anionic group or anion-forming group in the molecule, and having a solubility parameter (SP value) of 11 to 12 and a glass transition temperature of 40 to 150°C. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 08-218026 [Patent Document 2] International Publication No. 2020 / 166660 [Patent Document 3] Japanese Patent Publication No. 2000-198962 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, with the conventional wallpaper inks described in Patent Documents 1 to 3, it is difficult to obtain a printed layer that has a good balance of ink layer adhesion, leveling properties, and heat resistance. Furthermore, it is difficult to obtain a wallpaper ink with excellent drying properties.

[0010] The present invention aims to provide a wallpaper ink composition with excellent drying properties that can form a printed layer with excellent interlayer adhesion, leveling properties, and heat resistance, a laminate comprising a printed layer formed using the above wallpaper ink composition, and wallpaper comprising the above laminate. [Means for solving the problem]

[0011] The present invention has the following aspects. [1] A wallpaper ink composition comprising (meth)acrylic resin emulsion (A), polyurethane resin dispersion (B), free neutralizing agent (C), leveling agent, and aqueous medium, The glass transition temperature of the (meth)acrylic resin emulsion (A) is 60 to 100°C. The polyurethane resin dispersion (B) is a polycarbonate-based polyurethane resin. The polyurethane resin dispersion (B) has a breaking elongation of 40-300% as measured in accordance with JIS K7161-1:2014. The total solid content of the (meth)acrylic resin emulsion (A) and the polyurethane resin dispersion (B) is 65.0 to 90.0% by mass of the total mass of solids in the wallpaper ink composition. A wallpaper ink composition in which the mass ratio of the polyurethane resin dispersion (B) to the (meth)acrylic resin emulsion (A) is 0.25 to 0.70. [2] The wallpaper ink composition according to [1], further comprising either or both of texanol and dipropylene glycol-n-butyl ether. [3] The wallpaper ink composition according to [1] or [2], wherein the leveling agent is an acetylenediol-based leveling agent. [4] The wallpaper ink composition according to any one of [1] to [3], further comprising a thickening agent, wherein the thickening agent is a urethane association type thickening agent. [5] The wallpaper ink composition according to any one of [1] to [4], wherein the free neutralizing agent (C) contains ammonia or an amine-based neutralizing agent, and the content of the free ammonia and the amine-based neutralizing agent is 0.2 to 2.5% by mass with respect to the total mass of the wallpaper ink composition. [6] A wallpaper ink composition according to any one of [1] to [5], further comprising silica. [7] A wallpaper ink composition according to any of [1] to [6], for gravure printing. [8] A laminate comprising a wallpaper substrate and a printed layer formed on one surface of the wallpaper substrate using any of the wallpaper ink compositions described in [1] to [6]. [9] A laminate comprising a wallpaper substrate and a printed layer formed on one surface of the wallpaper substrate using the wallpaper ink composition described in [7]. Wallpaper comprising the laminate described in

[10] [8]. Wallpaper comprising the laminate described in

[11] [9]. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a wallpaper ink composition with excellent drying properties that can form a printed layer with excellent interlayer adhesion, leveling properties, and heat resistance, a laminate comprising a printed layer formed using the above wallpaper ink composition, and wallpaper comprising the above laminate. [Modes for carrying out the invention]

[0013] The present invention will now be described in detail. The following embodiments are merely illustrative for illustrating the present invention and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from its spirit. The definitions used herein are as follows: "Aqueous medium" refers to a liquid medium that contains water. "Liquid medium" refers to volatile liquids such as water and organic solvents. The content of (meth)acrylic resin emulsion and polyurethane resin dispersion is all calculated on a solids basis. The "solid content" of a wallpaper ink composition refers to the components of the wallpaper ink composition excluding the liquid medium, and is the component that ultimately forms the ink layer. Specifically, it can be measured in accordance with JIS K 5601-1-2:2008. The same applies to the solid content of (meth)acrylic resin emulsions and polyurethane resin dispersions. The term "coating film" refers to a coating film formed by the ink composition for wallpaper of the present invention. That is, in the present specification, "printed layer" and "coating film" are synonymous. The term "(meth)acrylate" is a general term for "acrylate" and "methacrylate". The term "(meth)acrylic acid" is a general term for "acrylic acid" and "methacrylic acid".

[0014] The glass transition temperatures of the (meth)acrylic resin emulsion and the polyurethane resin dispersion can be measured in the following manner in accordance with JIS K 7121:2012. Using a differential scanning calorimeter, the glass transition temperature is determined from the intersection of the baseline and the tangent line of the endothermic curve in the curve (DSC curve) obtained by heating 10 mg of the solid content of the (meth)acrylic resin emulsion or the polyurethane resin dispersion from -100°C to 160°C at a rate of 20°C / min.

[0015] The acid value of the (meth)acrylic resin emulsion and the polyurethane resin dispersion is expressed as the number of milligrams of potassium hydroxide required to neutralize acid groups such as carboxy groups per 1 g of the solid content of the sample, and can be measured in accordance with JIS K 5601-2-1:1999.

[0016] ≪Ink Composition for Wallpaper≫ The ink composition for wallpaper of the present embodiment (hereinafter also simply referred to as "ink composition") contains a (meth)acrylic resin emulsion (A), a polyurethane resin dispersion (B), a free neutralizing agent (C), a leveling agent, and an aqueous medium. The ink composition may further contain a film-forming auxiliary. The ink composition may further contain a thickener. The ink composition may further contain an extender pigment. The ink composition may further contain other components besides the (meth)acrylic resin emulsion (A), the polyurethane resin dispersion (B), the free neutralizing agent (C), the leveling agent, the aqueous medium, the film-forming auxiliary, the thickener, and the extender pigment.

[0017] <(Meth)acrylic resin emulsion (A)> (Meth)acrylic resin emulsion (A) is an emulsion-type (meth)acrylic resin. (Meth)acrylic resin emulsion (A) has units based on (meth)acrylate. (Meth)acrylic resin emulsion (A) typically has a core-shell structure. The core portion of the core-shell structure is preferably a hydrophobic (meth)acrylic resin. The shell portion of the core-shell structure is preferably a hydrophilic (meth)acrylic resin. The core portion and the shell portion may be bonded together by a crosslinking agent.

[0018] The hydrophobic (meth)acrylic resin of the core is typically a resin containing units based on (meth)acrylate. Examples of such resins include homopolymers of (meth)acrylate, copolymers of two or more (meth)acrylates, and copolymers of (meth)acrylate and monomers other than (meth)acrylate. The (meth)acrylate is preferably one that does not have a carboxyl group.

[0019] The hydrophilic (meth)acrylic resin of the shell is typically a resin containing units based on carboxyl group-containing monomers. Examples of such resins include homopolymers of carboxyl group-containing monomers, copolymers of two or more carboxyl group-containing monomers, and copolymers of carboxyl group-containing monomers and monomers other than carboxyl group-containing monomers. The monomers other than carboxyl group-containing monomers can be any monomer that does not have a carboxyl group, and may be (meth)acrylates or monomers other than (meth)acrylates.

[0020] Examples of (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. (Meth)acrylate may be used alone or in combination of two or more types.

[0021] Examples of monomers containing a carboxyl group include (meth)acrylic acid, maleic acid (maleic anhydride), fumaric acid, and itaconic acid (itaconic anhydride). The carboxyl group-containing monomer may be used alone or in combination of two or more types.

[0022] Examples of monomers other than (meth)acrylates and carboxyl group-containing monomers include conjugated diene compounds such as 1,3-butadiene, isoprene, and chloroprene; aromatic vinyl compounds such as styrene, α-methylstyrene, halogenated styrene, and divinylbenzene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; and unsaturated carboxylic acid esters such as diethyl maleate, dibutyl maleate, dibutyl fumarate, diethyl itaconate, and dibutyl itaconate. These monomers may be used individually or in combination of two or more.

[0023] The (meth)acrylic resin emulsion (A) may be self-crosslinking. If the (meth)acrylic resin emulsion (A) is self-crosslinking, the (meth)acrylic resin emulsion (A) typically contains constituent units based on reactive functional group-containing monomers. These constituent units may be contained in the core, the shell, or both. Examples of monomers containing reactive functional groups include monomers containing alkoxysilyl groups, monomers containing hydrazine groups, monomers containing epoxy groups, monomers containing methylol groups, monomers containing alkoxymethyl groups, dihydrazide adipate, diacetone acrylamide, vinyl acetoacetate, allyl acetoacetate, and acetoacetoxyalkyl (meth)acrylate. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 2,3-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, and allyl glycidyl ether. Examples of acetoacetoxyalkyl (meth)acrylates include acetoacetoxyethyl (meth)acrylate, acetoacetoxypropyl (meth)acrylate, acetoacetoxybutyl (meth)acrylate, and 2,3-di(acetoacetoxy)propyl (meth)acrylate. Reactive functional group-containing monomers may be used individually or in combination of two or more.

[0024] The total content of units based on (meth)acrylate and units based on carboxyl group-containing monomers relative to the total mass of all monomer units constituting the (meth)acrylic resin emulsion (A) is preferably 20 to 100% by mass, more preferably 50 to 100% by mass, and even more preferably 80 to 100% by mass.

[0025] In the (meth)acrylic resin emulsion (A), the mass ratio of the core portion to the shell portion (core portion:shell portion) is preferably 20:80 to 90:10, more preferably 25:75 to 85:15, and even more preferably 30:70 to 80:20. If the amount of core portion is greater than the above range and the amount of shell portion is less, the storage stability of the ink composition, the film-forming ability, and the adhesion of the resulting printed layer to the wallpaper substrate will be slightly reduced. If the amount of core portion is less than the above range and the amount of shell portion is greater, the blocking resistance, abrasion resistance, and water abrasion resistance of the resulting printed layer will be slightly reduced.

[0026] The acid value of (meth)acrylic resin emulsion (A) is preferably 60 mgKOH / g or less, more preferably 55 mgKOH / g or less, and even more preferably 50 mgKOH / g or less. Furthermore, the acid value of (meth)acrylic resin emulsion (A) may be 0 mgKOH / g or more, 1 mgKOH / g or more, 5 mgKOH / g or more, 10 mgKOH / g or more, or 20 mgKOH / g or more. The above upper and lower limits can be combined as appropriate. If the acid value exceeds the above upper limit, the adhesion, alkali resistance, and water friction resistance of the resulting printed layer to the wallpaper substrate will be slightly reduced.

[0027] The average particle size of the (meth)acrylic resin emulsion (A) is preferably 38 to 600 nm, more preferably 39 to 400 nm, and even more preferably 40 to 350 nm. If the average particle size of the (meth)acrylic resin emulsion (A) is below the lower limit, the adhesion, alkali resistance, and water friction resistance of the resulting printed layer to the wallpaper substrate will be slightly reduced. If the average particle size of the (meth)acrylic resin emulsion (A) is above the upper limit, the storage stability of the ink composition will be slightly reduced. The average particle size of (meth)acrylic resin emulsion (A) is the particle size at which the volume-based cumulative frequency reaches 50% (median diameter: D50) calculated from the volume-based particle size distribution obtained by dynamic light scattering.

[0028] The glass transition temperature of (meth)acrylic resin emulsion (A) is 60 to 100°C, preferably 62 to 90°C, and more preferably 65 to 85°C. If the glass transition temperature of (meth)acrylic resin emulsion (A) is below the above lower limit, the heat resistance of the resulting printed layer will decrease. In addition, the resolubility of the ink composition will decrease. If the resolubility of the ink composition is low, when the ink composition remaining in the cells of the gravure plate or on the flexographic plate dries, it can cause transfer defects. Resolubility refers to the ability to redissolve the ink composition in the aqueous medium that constitutes the ink composition before it dries and causes transfer defects. If the glass transition temperature of (meth)acrylic resin emulsion (A) exceeds the above upper limit, the interlayer adhesion of the ink in the resulting printed layer will decrease. In addition, the adhesion to the wallpaper substrate will also decrease.

[0029] The weight-average molecular weight of the (meth)acrylic resin emulsion (A) is preferably 30,000 to 1,000,000, more preferably 50,000 to 900,000, and even more preferably 70,000 to 800,000. If the weight-average molecular weight of the (meth)acrylic resin emulsion (A) is below the lower limit, the abrasion resistance, water abrasion resistance, and blocking resistance of the resulting printed layer will be slightly reduced. If the weight-average molecular weight of the (meth)acrylic resin emulsion (A) is above the upper limit, the storage stability of the ink composition will be slightly reduced. The weight-average molecular weight of (meth)acrylic resin emulsion (A) is the weight-average molecular weight converted to the standard polystyrene molecular weight and is measured by gel permeation chromatography (GPC). The same applies to other resins.

[0030] The (meth)acrylic resin emulsion (A) may be one produced by a known manufacturing method or a commercially available product. In the production of (meth)acrylic resin emulsion (A), the polymerization method of the monomers is not particularly limited, but examples include radical polymerization, anionic polymerization, cationic polymerization, etc. In particular, radical polymerization includes bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc. Among these, emulsion polymerization is preferred. Emulsion polymerization is a method of polymerization in which the monomers used for polymerization are polymerized in an aqueous medium in the presence of an emulsifier and a polymerization initiator. (Meth)acrylic resin emulsion (A) may be produced by compounding the core and shell parts after producing them separately, or it may be produced by multi-step emulsion polymerization. The polymerization mode may be any of random copolymer, block copolymer, graft copolymer, etc.

[0031] (Meth)acrylic resin emulsion (A) may be used alone or in combination of two or more types.

[0032] <Polyurethane resin dispersion (B)> Polyurethane resin dispersion (B) is a resin obtained by aqueousizing a polyurethane resin having urethane bonds and carboxyl groups. The above polyurethane resin can be produced from a polyvalent isocyanate compound, a polyol compound, and a compound having a carboxyl group and at least two active hydrogen-containing groups. For example, it can be synthesized by reacting a diisocyanate compound, a polyol compound, a compound having a carboxyl group and at least two active hydrogen-containing groups, and an extender as needed to synthesize a urethane prepolymer having a carboxyl group in the molecule and an isocyanate group at the terminal, then self-emulsifying by adding a neutralizing agent and water as described later, and reacting it with a diamine compound as needed.

[0033] In other words, polyurethane resin dispersion (B) is a water-based dispersion type polyurethane resin. Furthermore, polyurethane resin dispersion (B) is a polycarbonate-based polyurethane resin. The ink composition, by containing polyurethane resin dispersion (B), improves the inter-layer adhesion of the resulting printed layer. It also improves adhesion to the wallpaper substrate.

[0034] Examples of polyvalent isocyanate compounds include aliphatic, alicyclic, and aromatic polyvalent isocyanate compounds. Specific examples of polyvalent isocyanate compounds include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate; hydrogenated diisocyanates. Diphenylmethane diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexyl Alicyclic diisocyanates such as xane diisocyanates, 1,4-bis(isocyanate-methyl)cyclohexane, and 1,3-bis(isocyanate-methyl)cyclohexane; m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 4,4'-diphenylmethanediisocyanate, 2,4- or 2,6-tolylenediisocyanate, 4,4'-toluidinediisocyanate, dianisidinediisocyanate, Examples include aromatic diisocyanates such as 4,4'-diphenyl ether diisocyanate; polyvalent isocyanate compounds having allophanate, nurate, or biuret structures obtained by polymerizing the above diisocyanates; triisocyanates such as 1,3,5-triisocyanatebenzene, 2,4,6-triisocyanatetoluene, and 1,3,5-triisocyanatehexane; and polyisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate. These polyvalent isocyanate compounds may be used individually or in combination of two or more.

[0035] Examples of polyol compounds include polycarbonate polyols obtained by reacting glycols with dimethyl carbonate, diphenyl carbonate, diethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, phosgene, etc. Examples of glycols include saturated or unsaturated glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, octanediol, 1,9-nonanediol, 1,8-nonanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A. Polyol compounds may be used individually or in combination of two or more.

[0036] Compounds having a carboxyl group and at least two active hydrogen-containing groups are necessary to introduce the carboxyl group required to make polyurethane resins aqueous. Active hydrogen-containing groups are functional groups that can react with isocyanate groups, with hydroxyl groups and amino groups being typical examples. Specifically, examples include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, diaminopropionic acid, lysine, ornithine, asparagine, glutamine, and diaminobenzoic acid. Compounds having a carboxyl group and at least two active hydrogen-containing groups may be used individually or in combination of two or more.

[0037] Diamine compounds are used as extension agents. Diamine compounds are used to extend the urethane prepolymer by reacting with the isocyanate groups at the ends of the resulting urethane prepolymer, thereby forming urea bonds. Specifically, examples include hydroxyl group-containing diamine compounds such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine; and ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, and dicyclohexylmethane-4,4'-diamine. The growth extender may be used alone or in combination of two or more types.

[0038] In addition to the above, other extenders and reaction inhibitors other than known diamine compounds may be used as needed in the synthesis of polyurethane resin dispersion (B). Alternatively, a silanol group may be introduced by reacting a hydrolyzable silicon group-containing compound with the reaction product of a polyvalent isocyanate compound and a polyol compound.

[0039] The weight-average molecular weight of the polyurethane resin dispersion (B) is preferably 50,000 to 1,000,000, more preferably 100,000 to 700,000, and even more preferably 100,000 to 500,000. If the weight-average molecular weight of the polyurethane resin dispersion (B) is below the lower limit, the heat resistance of the resulting printed layer will be slightly reduced. If the weight-average molecular weight of the polyurethane resin dispersion (B) is above the upper limit, the inter-ink adhesion of the resulting printed layer will be slightly reduced.

[0040] The elongation at break (tensile strain) of polyurethane resin dispersion (B), measured in accordance with JIS K7161-1:2014, is 40-300%, preferably 50-190%, more preferably 60-160%, and even more preferably 80-150%. If the polyurethane resin dispersion (B) is a commercially available product and the manufacturer discloses the elongation at break value, the above value can be used. If the elongation at break exceeds the above upper limit, the inter-ink adhesion of the resulting printed layer will decrease. Furthermore, the adhesion to the wallpaper substrate will also decrease.

[0041] Polyurethane resin dispersion (B) may be used alone or in combination of two or more types.

[0042] The above-mentioned elongation at break is a parameter that correlates with the hardness of the polyurethane resin dispersion (B). When the hardness of the polyurethane resin dispersion (B) is high, the elongation at break tends to be low.

[0043] The hardness (elongation at break) of the polyurethane resin dispersion (B) can be controlled, for example, by the type, physical properties, and composition of the polyisocyanate compound and the polyol compound. Alternatively, the polyurethane resin dispersion (B) can be composed of a hard segment and a soft segment, and its hardness can be controlled by adjusting the composition and physical properties of at least one of the hard or soft segments. An example of controlling the hardness of the polyurethane resin dispersion (B) is shown below. Long-chain polyol compounds are used as the polyol compounds, and the molecular weight of the long-chain polyol compounds is adjusted. Long-chain polyol compounds are polyol compounds with a number-average molecular weight of 400 or more. When the number-average molecular weight of the long-chain polyol compound is reduced, the polyurethane resin dispersion (B) tends to become harder. The ratio of hard segments to soft segments in the polyurethane resin dispersion (B) is adjusted. Increasing the proportion of hard segments tends to make the polyurethane resin dispersion (B) harder. The proportion of hard segments can be controlled, for example, by adjusting the proportion of at least one of urethane bonds and urea bonds in the polyurethane resin dispersion (B). A higher proportion of urethane or urea bonds tends to increase the proportion of hard segments in the polyurethane resin dispersion (B). The proportion of urethane or urea bonds can be quantified using the amine value. As described above, the elongation at break of polyurethane resin dispersion (B) is controllable for those skilled in the art.

[0044] <Free neutralizing agent (C)> The neutralizing agent is used to neutralize acidic groups (e.g., sulfonic acid groups, carboxyl groups) in the resins in order to make the (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) aqueous. Any excess neutralizing agent is present in the ink composition as free neutralizing agent (C). Specifically, examples include ammonia; organic amines such as monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, N-methylmorpholine, and 2-amino-2-ethyl-1-propanol (amine-based neutralizing agents); and inorganic alkalis such as sodium hydroxide and potassium hydroxide. In particular, from the viewpoint of drying properties, ammonia and amine-based neutralizing agents are preferred, with ammonia, trimethylamine, triethylamine, triethanolamine, and 2-amino-2-methyl-1-propanol being preferred. The neutralizing agent may be used alone or in combination of two or more types.

[0045] <Leveling agent> By including a leveling agent in the ink composition, the leveling properties of the resulting printed layer can be improved. Examples of leveling agents include acetylenediol-based leveling agents, silicone-based leveling agents such as polyether-modified polydimethylsiloxane and polyester-modified polydimethylsiloxane, and (meth)acrylic-based leveling agents such as polyacrylates, with acetylenediol-based leveling agents being preferred. An example of an acetylenediol-based leveling agent is "Acetylenel E13T" manufactured by Kawaken Fine Chemicals Co., Ltd. Leveling agents may be used individually or in combination of two or more types.

[0046] <Aqueous medium> Examples of aqueous media include water; and mixed solvents of water and organic solvents. The organic solvent is not particularly limited as long as it is soluble in water, but examples include alcoholic solvents such as methanol, ethanol, n-propanol, i-propanol, n-butanol, and i-butanol; and ketoneic solvents such as acetone. However, even if glycols and glycol derivatives are liquid and soluble in water at 25°C, they are not included in aqueous media in this specification. Glycol derivatives mean glycol ethers and glycol esters. The above glycol derivatives are film-forming aids as described later in this specification. The above glycols are other components as described later in this specification. These organic solvents may be used individually or in combination of two or more.

[0047] <Membrane-forming agent> To lower the minimum film-forming temperature of the ink composition and to form a uniform and strong printed layer even at low temperatures, the ink composition may contain additional film-forming aids. Examples of film-forming aids include glycol derivatives that are liquid at 25°C. Examples include glycol ethers such as butyl cellosolve, diethylene glycol butyl ether, polypropylene glycol methyl ether, propylene glycol methyl ether, propylene glycol-n-propyl ether, dipropylene glycol-n-butyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, dipropylene glycol dimethyl ether, and tripropylene glycol-n-butyl ether, as well as glycol esters such as texanol. Among these, texanol and dipropylene glycol-n-butyl ether are preferred because they are excellent at lowering the minimum film-forming temperature.

[0048] <Thickening agent> A thickening agent may be further added to the ink composition for the purpose of increasing its viscosity and improving its stability. Examples of thickeners include polyurethane-based thickeners, acrylic-based thickeners, polyamide-based thickeners, cellulose-based thickeners, and clay minerals such as bentonite. Among these, polyurethane-based thickeners are preferred because they are excellent at improving the storage stability of the ink composition, and among these, associated polyurethane-based thickeners (hereinafter also referred to as "urethane associated thickeners") are particularly preferred.

[0049] Associative thickeners are polymers that have both hydrophobic and hydrophilic groups in their molecules. The hydrophobic groups of the thickener interact with each other or with hydrophobic substances such as resins through intermolecular interactions, forming a network structure and increasing the viscosity of the ink composition. In addition, the viscosity of the ink composition is further increased when the hydrophilic groups of the thickener interact with the hydrophilic groups on the emulsion surface of (meth)acrylic resin emulsion (A) or polyurethane resin dispersion (B). Examples of hydrophobic groups in association-type thickeners include alkyl groups and phenyl groups. Examples of hydrophilic groups in associated thickeners include hydroxyl groups, amide groups, and carboxyl groups.

[0050] Examples of urethane-associated thickeners include urethane-modified polyethers and polyether polyol-based urethane prepolymers.

[0051] Examples of commercially available urethane-associated thickeners include the "SN Thickener" series manufactured by Sunopco Corporation. The thickening agent may be used alone or in combination of two or more types.

[0052] <Body pigments> Extender pigments are solid particles formed from inorganic materials. Examples of extender pigments include barium sulfate, calcium sulfate, calcium carbonate, calcium silicate, magnesium silicate, silica, alumina, zirconia, tin oxide, clay, and kaolin. Among these, silica is preferred from the viewpoint of superior matte finish, design appeal, and cost-effectiveness. Extender pigments may be used individually or in combination of two or more types.

[0053] The average particle size of the extender pigment is preferably 12 μm or less, more preferably 11 μm or less, and even more preferably 10 μm or less. The lower limit of the average particle size is not particularly limited, but for example, it is 1 μm or more. If the average particle size of the extender pigment is less than the above lower limit, the blocking resistance and matte properties of the resulting printed layer may be slightly reduced. If the average particle size of the extender pigment exceeds the above upper limit, the storage stability of the ink composition may be slightly reduced. The average particle size of extender pigments is defined as the particle size at 50% of the volume-based cumulative value (D50) in the particle size distribution measured by laser diffraction-scattering if the average particle size is 100 nm or more, and as the particle size at 50% of the number-based cumulative value (D50) in the particle size distribution measured using a transmission electron microscope (TEM) if the average particle size is less than 100 nm. If the extender pigment is a commercially available product, the above value can be used if the manufacturer discloses the D50 value measured by laser diffraction-scattering.

[0054] Commercial silica products may be used. Examples of commercially available products include the "SYLYSIA" series, "SYLOPHOBIC" series, and "SYLOSPHERE" series from Fuji Silysia Chemical Co., Ltd., and the "NipSeal SS" series, "NipSeal WE" series, "NipSeal E" series, "NipSeal K" series, and "NipSeal AZ" series from Tosoh Silica Co., Ltd.

[0055] <Other ingredients> Other components include, for example, binder resins other than (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B), pigments other than extender pigments (coloring pigments), anti-settlement agents, UV absorbers, antioxidants, dispersants, waxes, corrosion inhibitors, defoamers, lubricants, stabilizers, surface modifiers, surfactants, silicone-based additives, foam inhibitors, drying agents, release agents, and wetting agents. These other components may be used individually or in combination of two or more. An example of a drying agent is glycol that is liquid at 25°C. An example of a release agent is glycol that is solid at 25°C. An example of such glycol is polyethylene glycol (PEG) with a number average molecular weight of 1500 or more. The ink composition of this embodiment may contain both an extender pigment and a coloring pigment, or it may contain an extender pigment and not contain a coloring pigment, or it may contain a coloring pigment and not contain an extender pigment. An ink composition containing an extender pigment and not containing a coloring pigment is known as an extender and is used to adjust the concentration of an ink (containing a coloring pigment).

[0056] Other binder resins include, for example, aqueous resins other than (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B). Examples of such aqueous resins include aqueous urethane resins other than polycarbonate-based polyurethane resins, aqueous polyolefin resins, and aqueous vinyl chloride-vinyl acetate copolymer resins, aqueous ethylene-vinyl acetate copolymer resins, and so on. Examples of water-based polyurethane resins other than polycarbonate-based polyurethane resins include polyether-based polyurethane resins, polyester-based polyurethane resins, polyolefin-based polyurethane resins, and polyether ester-based polyurethane resins.

[0057] <Composition of the ink composition> The total solid content of the (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) is 65.0 to 90.0% by mass, preferably 68.0 to 85.0% by mass, more preferably 70.0 to 80.0% by mass, and even more preferably 72.0 to 78.0% by mass, relative to the total mass of solid content of the ink composition. If the total content is below the lower limit, the interlayer adhesion and leveling properties of the resulting printed layer will decrease. The drying properties of the ink composition will also decrease. If the total content exceeds the upper limit, the leveling properties of the resulting printed layer will decrease. The resolubility of the ink composition will also decrease.

[0058] The total solid content of the (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) is preferably 10 to 23% by mass, more preferably 12 to 20% by mass, and even more preferably 14 to 18.5% by mass, relative to the total mass of the ink composition. If the total content is below the lower limit, the interlayer adhesion and leveling properties of the resulting printed layer will decrease. The drying properties of the ink composition will also decrease. If the total content exceeds the upper limit, the leveling properties of the resulting printed layer will decrease. The resolubility of the ink composition will also decrease.

[0059] The solid content of (meth)acrylic resin emulsion (A) is preferably 43 to 60% by mass, more preferably 45 to 55% by mass, and even more preferably 47 to 53% by mass, relative to the total mass of solid content of the ink composition. If the content of (meth)acrylic resin emulsion (A) is below the lower limit, the heat resistance of the resulting printed layer will be slightly reduced. If the content of (meth)acrylic resin emulsion (A) exceeds the upper limit, the leveling properties and interlayer adhesion of the resulting printed layer will be slightly reduced. In addition, the resolubility of the ink composition will be slightly reduced.

[0060] The solid content of (meth)acrylic resin emulsion (A) is preferably 6.5 to 16% by mass, more preferably 8 to 14% by mass, and even more preferably 9 to 12% by mass, relative to the total mass of the ink composition. If the content of (meth)acrylic resin emulsion (A) is below the lower limit, the heat resistance of the resulting printed layer will be slightly reduced. If the content of (meth)acrylic resin emulsion (A) exceeds the upper limit, the leveling properties and inter-layer adhesion of the resulting printed layer will be slightly reduced. In addition, the resolubility of the ink composition will be slightly reduced.

[0061] The solid content of the polyurethane resin dispersion (B) is preferably 17 to 32% by mass, more preferably 20 to 30% by mass, and even more preferably 22 to 28% by mass, relative to the total mass of solid content of the ink composition. If the content of polyurethane resin dispersion (B) is below the lower limit, the interlayer adhesion of the resulting printed layer will be slightly reduced. If the content of polyurethane resin dispersion (B) exceeds the upper limit, the heat resistance of the resulting printed layer will be slightly reduced.

[0062] The solid content of polyurethane resin dispersion (B) is preferably 3.2 to 8% by mass, more preferably 4 to 7% by mass, and even more preferably 4.5 to 6.5% by mass, relative to the total mass of the ink composition. If the content of polyurethane resin dispersion (B) is below the lower limit, the interlayer adhesion of the resulting printed layer will be slightly reduced. If the content of polyurethane resin dispersion (B) exceeds the upper limit, the heat resistance of the resulting printed layer will be slightly reduced.

[0063] The mass ratio of solids represented by polyurethane resin dispersion (B) / (meth)acrylic resin emulsion (A) is 0.25 to 0.70, preferably 0.3 to 0.68, more preferably 0.35 to 0.65, and even more preferably 0.4 to 0.6. If the mass ratio is below the lower limit, the inter-ink adhesion of the resulting printed layer will decrease. If the mass ratio exceeds the upper limit, the heat resistance of the resulting printed layer will decrease.

[0064] The total solid content of the (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass, relative to the total mass of solid content of the binder resin. It may also be 100% by mass.

[0065] The content of the free neutralizing agent (C) is preferably 0.05 to 3% by mass, more preferably 0.2 to 2.5% by mass, and even more preferably 0.4 to 2% by mass, based on the total mass of the ink composition. Ammonia or an amine-based neutralizing agent is preferred as the neutralizing agent. If the content of the free neutralizing agent (C) is below the lower limit, the resolubility of the ink composition will be slightly reduced. If the content of the free neutralizing agent (C) is above the upper limit, the drying properties of the ink composition will be slightly reduced.

[0066] The solid content of the leveling agent is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and even more preferably 3 to 6% by mass, relative to the total mass of solid content of the ink composition. If the leveling agent content is below the lower limit, the leveling properties of the resulting printed layer will be slightly reduced. If the leveling agent content exceeds the upper limit, the inter-ink adhesion of the resulting printed layer will be slightly reduced. In addition, the drying properties of the ink composition will be slightly reduced. Acetylenediol-based leveling agents are preferred as the leveling agent.

[0067] The content of the aqueous medium is preferably 30 to 90% by mass, more preferably 40 to 88% by mass, and even more preferably 50 to 85% by mass, relative to the total mass of the ink composition. If the content of the aqueous medium is below the lower limit, the ink fluidity tends to decrease. If the content of the aqueous medium exceeds the upper limit, the drying properties tend to decrease.

[0068] When the ink composition contains an extender pigment, the extender pigment content is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, and even more preferably 1 to 5% by mass, relative to the total mass of the ink composition. If the extender pigment content is below the lower limit, the opacity and color development of the resulting printed layer will be slightly reduced. If the extender pigment content exceeds the upper limit, the adhesion of the resulting printed layer to the wallpaper substrate will be slightly reduced. In addition, the ink fluidity of the ink composition may decrease.

[0069] When the ink composition contains a thickener, the solid content of the thickener is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, and even more preferably 0.5 to 3% by mass, relative to the total mass of the ink composition. A urethane-associated thickener is preferred, and a neutonian-based urethane-associated thickener is more preferred.

[0070] The solid content is preferably 10 to 30% by mass, more preferably 12 to 28% by mass, and even more preferably 15 to 25% by mass, relative to the total mass of the ink composition.

[0071] The content of other components is not particularly limited as long as it does not impair the effects of the present invention, but for example, it is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, even more preferably 0 to 10% by mass, particularly preferably 0 to 5% by mass, and particularly preferably 0 to 1% by mass, based on the total mass of the ink composition. If the ink composition contains other components, the content of these other components is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, relative to the total mass of the ink composition. If the content of these other components is above the above lower limit, the effects of these other components will be fully realized.

[0072] <Method for manufacturing wallpaper ink composition> The ink composition of this embodiment can be obtained, for example, by dissolving or dispersing in an aqueous medium one or more of the following: (meth)acrylic resin emulsion (A), polyurethane resin dispersion (B), neutralizing agent (free neutralizing agent (C)), leveling agent, and optionally a film-forming aid, thickener, extender pigment, and other components. The method of mixing each component is not particularly limited, and the components can be mixed by various methods. The method for dissolving or dispersing each component in an aqueous medium is not particularly limited and can be carried out using known dispersers. Examples of dispersers include paint shakers, ball mills, attritors, sand mills, bead mills, dyno mills, roll mills, dissolvers, ultrasonic mills, and high-pressure impact dispersers. In this case, the dispersion treatment may be performed once or multiple times using one type of disperser, or multiple dispersion treatments may be performed using two or more types of dispersers in combination.

[0073] <Applications, laminates, wallpaper> The ink composition of this embodiment is typically printed on a wallpaper substrate to form an ink layer. Examples of substrates for wallpaper include those in which a plastic film mainly composed of synthetic resin such as polyvinyl chloride (PVC) resin is laminated on a support such as paper or nonwoven fabric.

[0074] Examples of resins that make up plastic films include olefin resins such as polyvinyl chloride, polyethylene, and polypropylene; polyester resins such as ethylene-vinyl alcohol copolymer and polyethylene terephthalate (PET); (meth)acrylic resins; urethane resins; and styrene resins. These plastic films may be used individually or in combination of two or more types.

[0075] In addition to the resin mentioned above, the plastic film may contain foaming agents, plasticizers, fillers, flame retardants, stabilizers, pigments, and other additives as appropriate.

[0076] Examples of foaming agents include thermally decomposed chemical foaming agents such as azodicarbonamide (ADCA) and azobisisobutyronitrile, and foaming aids such as zinc oxide may be used in combination as needed. These foaming agents decompose thermally in the heating process described later (for example, at 180°C to 230°C) to generate gas, which expands the plastic film and imparts rich cushioning and design properties to the wallpaper.

[0077] As plasticizers, phthalate ester plasticizers such as diisononyl phthalate (DINP) and dioctyl phthalate (DOP), as well as non-phthalate plasticizers, are used.

[0078] Any known printing method may be used. The ink composition of this embodiment is suitable for gravure printing or flexographic printing, and is more suitable for gravure printing.

[0079] A laminate can be obtained by printing on a plastic film substrate for wallpaper using the ink composition of this embodiment.

[0080] The printed layer formed using the ink composition of this embodiment has high processability in both mechanical and chemical embossing.

[0081] In mechanical embossing, a cooled embossing roll is pressed against a plastic film that has been softened by heating and foaming to perform physical embossing. The heating temperature is, for example, 130 to 180°C. At this time, the printed layer is subjected to rapid tensile stress, but in the printed layer formed using the ink composition of this embodiment, the occurrence of film breakage and cracks is suppressed even at the bottom and rising portions of deep embossed grooves.

[0082] In chemical embossing, the foam inhibitor blended into the ink composition migrates into the plastic film during the heating process, locally inhibiting the decomposition reaction of the foaming agent. In this method, a steep step is created at the boundary between the foamed and non-foamed areas. However, the printed layer obtained from the ink composition of this embodiment has excellent leveling properties, allowing the inhibitor to penetrate uniformly, thus enabling the formation of a sharp and precise textured design. Furthermore, even at the formed steep step, the printed layer follows the shape changes of the substrate and is firmly adhered without peeling or cracking.

[0083] The wallpaper of this embodiment comprises the laminate described above. The wallpaper may further have a coating layer on the surface of the printed layer of the laminate. Examples of the coating layer include a layer made of treatment agents such as an antifouling agent, a matting agent, and an antibacterial agent.

[0084] <Mechanism of Action> The wallpaper ink composition of the present invention comprises a (meth)acrylic resin emulsion (A), a polyurethane resin dispersion (B), a free neutralizing agent, a leveling agent, and an aqueous medium. As shown in the examples described below, the inclusion of a (meth)acrylic resin emulsion (A) with a glass transition temperature of 60 to 100°C improves the heat resistance and interlayer adhesion of the resulting printed layer. Furthermore, the adhesion of the resulting printed layer to the wallpaper substrate and the resolubility of the ink composition are improved. In addition, the inclusion of a polycarbonate-based polyurethane resin as the polyurethane resin dispersion (B) improves the interlayer adhesion of the resulting printed layer. Furthermore, the adhesion of the resulting printed layer to the wallpaper substrate is improved. The elongation at break of the polyurethane resin dispersion (B), measured in accordance with JIS K7161-1:2014, is 40 to 300%, which improves the interlayer adhesion of the printed layer. Furthermore, the adhesion of the resulting printed layer to the wallpaper substrate is improved. Furthermore, by ensuring that the total content of (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) is within a specific range, the leveling properties and inter-ink adhesion of the resulting printed layer are improved. In addition, the drying properties and re-solubility of the ink composition are also improved. Furthermore, by ensuring that the mass ratio of (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) is within a specific range, the heat resistance and inter-ink adhesion of the resulting printed layer are improved. Furthermore, by including a leveling agent, the leveling properties of the resulting printed layer are improved. In the embodiments described later, a polyolefin film is used as the plastic film for the wallpaper substrate. Although polyolefin films tend to have lower adhesion to the printed layer than polyvinyl chloride films, the printed layer obtained by using the wallpaper ink composition of this embodiment has excellent adhesion to the substrate and inter-ink layer adhesion. [Examples]

[0085] 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 unless it exceeds the gist of the invention. Unless otherwise specified, "%" means "mass%".

[0086] [Raw materials used] <(Meth)acrylic resin emulsion (A)> ·A-1: Solids content: 40%, glass transition temperature: 70°C, weight-average molecular weight: 193,000, average particle size: 163 nm, has a core-shell structure. ·A-2: Solid content: 50%, glass transition temperature: 80°C, weight-average molecular weight: 220,000, average particle size: 131 nm, has a core-shell structure. ·A-3: Solids content: 50%, glass transition temperature: 53°C, weight-average molecular weight: 145,000, average particle size: 190 nm, has a core-shell structure. · A-4: Solids content: 50%, glass transition temperature: 105℃, weight-average molecular weight: 210,000, average particle size: 205nm, has a core-shell structure.

[0087] <Polyurethane resin dispersion (B)> B-1: Polycarbonate-based polyurethane resin, solids content: 30%, elongation at break: 100%. B-2: Polycarbonate-based polyurethane resin, solids content: 30%, elongation at break: 180%. B-3: Polycarbonate-based polyurethane resin, solids content: 30%, elongation at break: 66%. B-4: Polycarbonate-based polyurethane resin, solids content: 32%, elongation at break: 550%. B-5: Polyester-based polyurethane resin, solids content: 33%, elongation at break: 200%.

[0088] <Leveling agent> • Acetylenediol-based leveling agent, manufactured by Kawaken Fine Chemical Co., Ltd., product name "Acetylenel E13T", solid content: >98%.

[0089] <Neutralizing agent> Neutralizing agent: 2-amino-2-methyl-1-propanol, manufactured by ANGUS, product name "AMP-90", active ingredient: 90%. In Tables 1-5, it is referred to as "AMP-90". Neutralizing agent: Triethanolamine, active ingredient: 90%. In Tables 1-5, this is indicated as "TEA".

[0090] <Aqueous medium> ·Purified water.

[0091] <Optional ingredients> • Extender pigment: Silica, manufactured by Tosoh Silica Co., Ltd., product name "Nipsil E-1030", average particle size: 8.3 μm. In Tables 1-5, it is referred to as "Silica". • Urethane-associated thickener, manufactured by Sunopco Co., Ltd., product name "SN Thickener 623N", solids content: 30%. In Tables 1-5, it is referred to as "urethane-associated thickener". • Acrylic thickener, manufactured by Sunopco Co., Ltd., product name "SN Thickener 636", solids content: 30%. In Tables 1-5, it is referred to as "acrylic thickener". • Defoaming agent: Manufactured by ADEKA Corporation, product name "ADEKAnate B1016", solids content: 100%. • Film-forming agent: Texanol, active ingredient: 100%. In Tables 1-5, it is referred to as "Texanol". • Film-forming agent: Dipropylene glycol n-butyl ether, manufactured by Dow Chemical, trade name "Dawanol DPnB (registered trademark)", active ingredient: 100%. In Tables 1-5, it will be referred to as "Dawanol DPnB". • Corrosion inhibitor, manufactured by Sanwa Kasei Co., Ltd., product name "Fujilight BT-50A", solid content: 38.5%.

[0092] [Examples 1-15, Comparative Examples 1-9] <Preparation of wallpaper ink composition> According to the compositions shown in Tables 1-5, (meth)acrylic resin emulsion (A), polyurethane resin dispersion (B), leveling agent, neutralizing agent, aqueous medium, and optional components were mixed, and the resulting mixture was kneaded in a paint shaker to obtain an ink composition. In Tables 1-5, the content of (meth)acrylic resin emulsion (A), polyurethane resin dispersion (B), and other components in the composition [mass %] column represents the ratio of solids (mass %) to the total mass of the ink composition (however, for active ingredients that are not solids, such as free neutralizing agents, aqueous mediums, and film-forming aids, it represents the content of the active ingredient). The "residue" of the aqueous medium is the amount that makes up 100% of the total mass of the ink composition. A blank space means that the component was not included. The content of free neutralizing agent is the amount of neutralizing agent that is free and not used to neutralize acidic groups such as carboxyl groups in the resin. This free neutralizing agent is derived from the neutralizing agent included in (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) other than the solids, and from the additional neutralizing agent added as described above. In Tables 1 to 5, the "Solids Base" column refers to the amount of solids such as (meth)acrylic resin emulsion (A) and polyurethane resin dispersion (B) relative to the total mass of solids in the ink composition. For example, the content of (A) refers to the amount of (meth)acrylic resin emulsion (A) relative to the total mass of solids in the ink composition. The mass ratio of (B) / (A) refers to the mass ratio of solids represented by polyurethane resin dispersion (B) / (meth)acrylic resin emulsion (A).

[0093] <Creating printed materials> A mixture was prepared by mixing 95 parts by mass of the prepared ink composition with 5 parts by mass of a blue ink composition (manufactured by Dainichi Seika Kogyo Co., Ltd., product name "Hydric WP 63 Blue (D)") and diluting the mixture with water until the viscosity at 20°C, as measured using a Zahn cup #3, was 18 seconds, thereby preparing a printing ink. Using a gravure printing press equipped with a Helio 175 lines / inch gravure engraving plate (manufactured by Matsuo Sangyo Co., Ltd., product name "K Printing Proofer"), the prepared printing ink was applied to the surface of the foaming agent-containing polyolefin resin layer of a wallpaper sheet (paper / foaming agent-containing polyolefin resin laminate, thickness: 0.18 mm). The sheet was then dried at 80°C for 30 seconds to produce a printed material.

[0094] <Evaluation of adhesion to the substrate> The resulting printed material was subjected to a foaming treatment with 220°C hot air for 40 seconds. After that, cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface of the printed material, and then the cellophane adhesive tape was promptly peeled off. The condition of the printed layer remaining on the substrate was visually inspected, and the adhesion of the printed layer to the substrate was evaluated according to the following evaluation criteria. 5: The printed layer has not peeled off at all. 4. The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is greater than 0% and 5% or less. 3. The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is greater than 5% and less than or equal to 20%. 2: The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is greater than 20% and less than or equal to 50%. 1: The area of ​​the peeled-off printed layer is more than 50% of the total printed layer area.

[0095] <Evaluation of ink interlayer adhesion> Following the printing process, a test specimen was prepared by repeatedly applying and drying printing ink on the printing surface to create multiple layers of printed material. Then, cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface of the test specimen. The tape was then quickly removed, and its condition was visually inspected. The adhesion of the printed layers to the substrate was evaluated according to the following criteria. A score of 3-5 indicates excellent inter-ink layer adhesion. In the case of multiple printed layers, if only a portion of the printed layer migrated to the cellophane adhesive tape, this area of ​​the printed layer migrated to the cellophane adhesive tape was included in the calculation below. In a test specimen with a 5:5 layered printed surface, the area of ​​the printed surface transferred to the cellophane adhesive tape was less than 5%. 4. In a test specimen with four printed layers, the area of ​​the printed layer that migrated to the cellophane adhesive tape is less than 5%, provided that the requirements of item 5 above are not met. 3. In a test specimen with three printed layers that does not meet the requirements of item 4 above, the percentage of the printed layer area transferred to the cellophane adhesive tape is less than 5%. 2: In a test specimen with two laminated printed layers that does not meet the requirements of item 3 above, the percentage of the printed layer area transferred to the cellophane adhesive tape is less than 5%. 1: In a test specimen with two laminated printed layers that does not meet the requirements of item 2 above, the proportion of the printed layer area transferred to the cellophane adhesive tape exceeds 5%.

[0096] <Evaluation of drying properties> The printed surface of the obtained printed material was subjected to an abrasion resistance test using a JSPS-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which a white cloth (metal width 3) with a load of 200 gf was rubbed back and forth five times. After that, the appearance of the printed layer was visually inspected, and the drying properties were evaluated according to the evaluation criteria shown below. A score of 3 to 5 indicates excellent drying properties. 5: The area of ​​the printed layer that has migrated to the white cloth (gold cloth No. 3) is less than 5%. 4. The area of ​​the printed layer that has migrated to the white cloth (gold cloth No. 3) is 5% or more and less than 20%. 3. The percentage of the printed layer area that has migrated to the white cloth (gold cloth No. 3) side is 20% or more and less than 50%. 2: The area of ​​the printed layer that has migrated to the white cloth (gold cloth No. 3) is 50% or more and less than 80%. 1: The area of ​​the printed layer that has migrated to the white cloth (gold cloth No. 3) is 80% or more.

[0097] <Evaluation of leveling ability> The printed surface of the obtained printed material was visually inspected, and the leveling properties were evaluated according to the evaluation criteria shown below. A score of 3 to 5 indicates excellent leveling performance. 5: The printed coating is uniform. 4: Very slight unevenness can be observed in the printed coating. 3: Slight unevenness can be observed in the printed coating. 2: Unevenness in the printed coating is observed. 1: Significant unevenness in the printed coating is observed.

[0098] <Evaluation of resolubility> A Helio 175 line / inch gravure engraving plate, still coated with printing ink immediately after printing, was dried at 80°C for 10 seconds. One drop of water was then added and allowed to stand for 10 seconds. Afterward, the water was wiped off, the condition of the plate at the drop site was checked, and the resolubility was evaluated according to the following evaluation criteria. 5. No ink remains on the printing plate. 4: A very small amount of ink remains on the printing plate. 3: A small amount of ink remains on the printing plate. 2: Ink remains on the printing plate. 1: The ink has hardened on the printing plate and cannot be wiped off.

[0099] <Heat resistance evaluation> The resulting printed material was subjected to a foaming treatment with 220°C hot air for 40 seconds. Subsequently, using a heating and cooling molding machine (manufactured by Kodaira Seisakusho Co., Ltd., product name "200KN Heating and Cooling Molding Machine") and a metal mirror plate, the material was processed at 150°C and 6.8 kg / cm². 2After heat pressing the printed surface under the specified conditions, the printed surface was visually inspected, and its heat resistance was evaluated according to the evaluation criteria shown below. A score of 3 to 5 indicates excellent heat resistance. In cases 1 to 4 below, if two evaluation criteria apply regarding the area ratio and discoloration, the lower-numbered evaluation criterion is adopted. For example, if the area ratio of the printed layer transferred to the metal mirror plate is greater than 0% and 5% or less, and yellow discoloration is observed, it would fall under both 4 and 2, but in this case, 2 is selected. 5: The area of ​​the printed layer transferred to the metal mirror plate is 0%, and no discoloration is observed. 4: The percentage of the printed layer transferred to the metal mirror plate is greater than 0% and less than or equal to 5%, or a very slight yellow discoloration is observed. 3: The area of ​​the printed layer transferred to the metal mirror plate is greater than 5% and less than or equal to 10%, or a slight yellow discoloration is observed. 2: The area of ​​the printed layer transferred to the metal mirror plate is greater than 10% and less than or equal to 20%, or yellow discoloration is observed. 1: The area of ​​the printed layer that has transferred to the metal mirror plate exceeds 20%, or brown discoloration is observed.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] [Table 4]

[0104] [Table 5]

[0105] The printed layers obtained from the ink compositions of Examples 1 to 15 exhibited excellent interlayer adhesion, leveling properties, and heat resistance. Furthermore, the ink compositions also demonstrated excellent drying properties. The printed layers obtained from the ink compositions of Comparative Examples 1 to 9 showed inferior leveling properties and heat resistance. Additionally, some of the ink compositions also exhibited poor drying properties. [Industrial applicability]

[0106] The wallpaper ink composition of the present invention is useful because it has excellent drying properties, as well as excellent inter-layer adhesion, leveling properties, and heat resistance of the resulting printed layer.

Claims

1. A wallpaper ink composition comprising (meth)acrylic resin emulsion (A), polyurethane resin dispersion (B), free neutralizing agent (C), leveling agent, and aqueous medium, The glass transition temperature of the (meth)acrylic resin emulsion (A) is 60 to 100°C. The polyurethane resin dispersion (B) is a polycarbonate-based polyurethane resin. The polyurethane resin dispersion (B) has a breaking elongation of 40-300% as measured in accordance with JIS K7161-1:2014. The total solid content of the (meth)acrylic resin emulsion (A) and the polyurethane resin dispersion (B) is 65.0 to 90.0% by mass of the total mass of solid content of the wallpaper ink composition. The mass ratio of the solid content represented by the polyurethane resin dispersion (B) / (meth)acrylic resin emulsion (A) is 0.25 to 0.

70. A wallpaper ink composition in which the free neutralizing agent (C) contains ammonia or an amine-based neutralizing agent, and the content of the free ammonia and the amine-based neutralizing agent is 0.05 to 3% by mass relative to the total mass of the wallpaper ink composition.

2. The wallpaper ink composition according to claim 1, further comprising either or both of texanol and dipropylene glycol-n-butyl ether.

3. The wallpaper ink composition according to claim 1, wherein the leveling agent is an acetylenediol-based leveling agent.

4. The wallpaper ink composition according to claim 1, further comprising a thickening agent, wherein the thickening agent is a urethane-associated type thickening agent.

5. The wallpaper ink composition according to claim 1, further comprising silica.

6. A wallpaper ink composition according to any one of claims 1 to 5, for use in gravure printing.

7. A laminate comprising a wallpaper substrate and a printed layer formed on one surface of the wallpaper substrate using the wallpaper ink composition described in any one of claims 1 to 5.

8. A laminate comprising a wallpaper substrate and a printed layer formed on one surface of the wallpaper substrate using the wallpaper ink composition described in claim 6.

9. Wallpaper comprising the laminate described in claim 7.

10. Wallpaper comprising the laminate described in claim 8.

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