Ink compositions, laminates, and packaging materials

Abstract

To provide an ink composition capable of forming an ink layer with excellent adhesion to a substrate, blocking resistance, matte finish, and transparency. [Solution] An ink composition comprising a binder resin (A), a matting agent (B), and an organic solvent (C), wherein the binder resin (A) is a reaction product of a 5-membered cyclic carbonate compound formed by the reaction of an epoxy compound and carbon dioxide and an amine compound, and contains a polyhydroxypolyurethane resin (A1) having a hydroxyl value of 40 to 85 mgKOH / g and a vinyl chloride-vinyl acetate copolymer (A2), and the matting agent (B) contains silica (B1) having an average particle size of 2 to 10 μm and an extender pigment (B2) having an average particle size of 0.02 to 0.5 μm, and the (A2) / (A1) ratio on a solid content basis is 0.1 to 0.45 and the (B1) / (B2) ratio on a solid content basis is 0.05 to 0.5.

Description

[Technical Field]

[0001] The present invention relates to an ink composition, a laminate, and a packaging material. [Background technology]

[0002] Packaging materials using plastic film or other substrates, used for packaging food and daily necessities, are printed with gravure inks or similar materials for decorative purposes or to include information. In recent years, to further improve aesthetic appeal, printing with matte inks is sometimes applied to the entire surface of the printed layer formed by gravure inks or to the surface of the substrate opposite to the printed layer, either partially or completely. Furthermore, printing with matte inks may be applied not only to improve aesthetic appeal but also to improve various physical properties such as heat resistance, abrasion resistance, and non-slip properties.

[0003] Generally, matte inks contain matting agents. Silica and extender pigments are widely used as matting agents due to their properties and cost-effectiveness. The important physical properties required for matte inks are matte finish and transparency. Matte finish is important for achieving a sufficiently matte look, while transparency is important for ensuring that the image created by the printed layer is clearly visible when the matte ink layer is placed on the surface of the printed layer or on the surface of the substrate opposite the printed layer. However, generally, when designing to increase matte finish, the matte layer becomes whitish, compromising transparency and making it difficult to achieve a clear image.

[0004] Incidentally, in recent years, the biomass-based production of polyurethane resins has been actively promoted as an environmental initiative. This is based on the concept of carbon neutrality, where plants absorb carbon dioxide from the atmosphere through photosynthesis using sunlight as energy to grow, and therefore, the amount of carbon dioxide absorbed by photosynthesis during the plant's growth process and the amount of carbon dioxide emitted by burning the plant cancel each other out, thus having no impact on the increase or decrease of carbon dioxide in the atmosphere. Furthermore, in recent years, the development of new environmentally friendly polyurethane resins has been reported, based on the concept of carbon recycling rather than carbon neutrality, and utilizing carbon dioxide directly. Specifically, polyhydroxy polyurethane resins obtained by the addition reaction of cyclic carbonate compounds, which are obtained by reacting epoxy compounds with carbon dioxide, with amine compounds have been proposed. Due to the nature of its synthesis, this polyhydroxy polyurethane resin differs from ordinary polyurethane resins in that it has a chemical structure with hydroxyl groups in its side chains, and therefore possesses properties different from conventional polyurethane resins.

[0005] The use of the above-mentioned polyhydroxy polyurethane resin as a binder resin in printing inks is being considered. Patent Document 1 discloses a printing ink binder containing a polyhydroxypolyurethane resin and another resin, a crosslinking agent which is at least one of an alkyl titanate compound and a polyisocyanate compound, and a colorant. Patent Document 2 discloses a gravure printing ink containing a polyhydroxypolyurethane resin, a vinyl chloride-vinyl acetate copolymer, and a coloring agent. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-105827 [Patent Document 2] Japanese Patent Publication No. 2024-041313 [Overview of the project] [Problems that the invention aims to solve]

[0007] Patent documents 1 and 2 describe the use of inorganic pigments as colorants, listing silica, barium sulfate, calcium carbonate, and the like as inorganic pigments. While these inorganic pigments can be used as matting agents, the printing inks described in Patent Documents 1 and 2 are not intended for use as matting inks. According to the inventors' research, when using polyhydroxy polyurethane resin in matte inks, further investigation is required to achieve both superior mattiness and transparency. Furthermore, in matte inks, the surface of the formed matte ink layer has irregularities derived from the matting agent, resulting in extremely stringent requirements for coating properties such as blocking resistance, abrasion resistance, and adhesion to the substrate. Further investigation is necessary to meet these required coating properties.

[0008] The present invention has been made in view of these circumstances, and its object is to provide an ink composition capable of forming an ink layer with excellent adhesion to a substrate, blocking resistance, matte finish, and transparency, as well as a laminate and packaging material having an ink layer with excellent adhesion to a substrate, blocking resistance, matte finish, and transparency. [Means for solving the problem]

[0009] The present invention has the following aspects. [1] An ink composition containing a binder resin (A), a matting agent (B), and an organic solvent (C), The binder resin (A) is a reaction product of a 5-membered cyclic carbonate compound formed by the reaction of an epoxy compound and carbon dioxide, and an amine compound, and contains a polyhydroxypolyurethane resin (A1) having a hydroxyl value of 40-85 mgKOH / g, and a vinyl chloride-vinyl acetate copolymer (A2). The matting agent (B) contains silica (B1) with an average particle size of 2 to 10 μm and an extender pigment (B2) with an average particle size of 0.02 to 0.5 μm. The mass ratio (A2) / (A1) of the vinyl chloride-vinyl acetate copolymer (A2) to the polyhydroxy polyurethane resin (A1) in terms of solid content is 0.1 to 0.45, An ink composition characterized in that the mass ratio (B1) / (B2) of the silica (B1) to the extender pigment (B2) in terms of solid content is 0.05 to 0.5. [2] The ink composition according to [1], wherein the content of the binder resin (A) in terms of solid content is 25 to 50% by mass based on the total solid content of the ink composition. [3] The ink composition according to [1] or [2], wherein the content of the matting agent (B) in terms of solid content is 36 to 61.5% by mass based on the total solid content of the ink composition. [4] The ink composition according to any one of [1] to [3], wherein the silica (B1) is hydrophobic silica. [5] The ink composition according to any one of [1] to [4], further containing a hydrocarbon wax. [6] The ink composition according to any one of [1] to [5], further containing a chlorinated polyolefin resin. [7] The ink composition according to any one of [1] to [6], further containing resin beads. [8] The ink composition according to any one of [1] to [7], further containing a curing agent. [9] The ink composition according to any one of [1] to [8], which is for gravure printing.

[10] A laminate comprising a plastic film and an ink layer provided on the plastic film, wherein the ink layer is a layer formed from the ink composition according to any one of [1] to [9].

[11] A packaging material comprising the laminate according to

[10] . [Advantages of the Invention]

[0010] According to the present invention, it is possible to provide an ink composition capable of forming an ink layer excellent in adhesion to a substrate, blocking resistance, matting property and transparency, and a laminate and a packaging material having an ink layer excellent in adhesion to a substrate, blocking resistance, matting property and transparency.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail. The following embodiments are merely illustrative for explaining the present invention, and it is not intended to limit the present invention only to these embodiments. The present invention can be implemented in various modes without departing from its gist. The content of the binder resin (A) in this specification is all in terms of solid content. In this specification, "solid content" refers to the components among the components contained in the ink composition excluding volatile media such as organic solvents, and is the component that will finally form the ink layer, specifically measured in accordance with JIS K 5601-1-2:2008. In this specification, "coating film" refers to the coating film formed by the ink composition of the present invention. "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0012] 〔Ink Composition〕 The ink composition according to an embodiment of the present invention contains a binder resin (A), a matting agent (B), and an organic solvent (C). The binder resin (A) contains a polyhydroxy polyurethane resin (A1) and a vinyl chloride-vinyl acetate copolymer (A2). The matting agent (B) contains silica (B1) having an average particle diameter of 2 to 10 μm and an extender pigment (B2) having an average particle diameter of 0.02 to 0.5 μm. Therefore, the ink composition contains a polyhydroxy polyurethane resin (A1), a vinyl chloride-vinyl acetate copolymer (A2), silica (B1) having an average particle diameter of 2 to 10 μm, an extender pigment (B2) having an average particle diameter of 0.02 to 0.5 μm, and an organic solvent (C). The ink composition may further contain components (optional components) other than the polyhydroxy polyurethane resin (A1), the vinyl chloride-vinyl acetate copolymer (A2), silica (B1), the extender pigment (B2), and the organic solvent (C) as necessary, as long as the effects of the present invention are not impaired.

[0013] [Binder resin (A)] The binder resin (A) contains polyhydroxypolyurethane resin (A1) and vinyl chloride-vinyl acetate copolymer (A2).

[0014] <Polyhydroxypolyurethane resin (A1)> Polyhydroxypolyurethane resin (A1) is a reaction product of a five-membered cyclic carbonate compound formed by the reaction of an epoxy compound and carbon dioxide, and an amine compound, with a hydroxyl value of 40-85 mgKOH / g.

[0015] Polyhydroxypolyurethane resin (A1) is synthesized by reacting an epoxy compound with carbon dioxide in the presence of a catalyst, and then reacting the resulting five-membered cyclic carbonate compound with an amine compound.

[0016] Examples of epoxy compounds used in synthesis include the following compounds. These epoxy compounds may be used individually or in combination of two or more. When an epoxy compound is reacted with carbon dioxide, the epoxy ring of the epoxy compound becomes a five-membered ring with a carbonate bond in its ring skeleton.

[0017] [ka]

[0018] [ka]

[0019] Examples of catalysts used in synthesis include base catalysts and Lewis acid catalysts. Examples of base catalysts include tertiary amines such as triethylamine, tributylamine, diazabicycloundecene, diazabicyclooctane, and pyridine; alkali metal salts such as lithium chloride, lithium bromide, lithium fluoride, and sodium chloride; alkaline earth metal salts such as calcium chloride; quaternary ammonium salts such as tetrabutylammonium chloride, tetraethylammonium bromide, and benzyltrimethylammonium chloride; carbonates such as potassium carbonate and sodium carbonate; metal acetates such as zinc acetate, lead acetate, copper acetate, and iron acetate; metal oxides such as calcium oxide, magnesium oxide, and zinc oxide; and phosphonium salts such as tetrabutylphosphonium chloride. Examples of Lewis acid catalysts include tin compounds such as tetrabutyltin, dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin octoate. These catalysts may be used individually or in combination of two or more.

[0020] Examples of amine compounds used in synthesis include methylenediamine, ethylenediamine, trimethylenediamine, 1,3-diaminopropane, hexamethylenediamine, octamethylenediamine, phenylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(phenylamine), 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, metaxylylenediamine, paraxylylenediamine, 1,4-cyclohexanediamine, 4,4'-diaminocyclohexylmethane, 1,4'-diaminomethylcyclohexane, isophoronediamine, monoethanoldiamine, ethylaminoethanolamine, hydroxyethylaminopropylamine, and bis(aminopropyl)piperazine. These amine compounds may be used individually or in combination of two or more.

[0021] The hydroxyl value of polyhydroxypolyurethane resin (A1) is 40 to 85 mgKOH / g, preferably 45 to 75 mgKOH / g, and more preferably 50 to 70 mgKOH / g. When the hydroxyl value of polyhydroxypolyurethane resin (A1) is above the lower limit, the ink layer exhibits excellent adhesion to the substrate, abrasion resistance, and heat resistance. When the hydroxyl value of polyhydroxypolyurethane resin (A1) is below the upper limit, the ink layer exhibits excellent blocking resistance, solubility of polyhydroxypolyurethane resin (A1) in organic solvents, and ink stability.

[0022] The weight-average molecular weight (hereinafter also referred to as Mw) of the polyhydroxypolyurethane resin (A1) is preferably 10,000 to 100,000, more preferably 20,000 to 80,000, and particularly preferably 30,000 to 60,000. When the Mw of the polyhydroxypolyurethane resin (A1) is above the lower limit, the blocking resistance, abrasion resistance, and heat resistance of the ink layer are better. When the Mw of the polyhydroxypolyurethane resin (A1) is below the upper limit, the adhesion of the ink layer to the substrate is better. In this specification, Mw is the value obtained by gel permeation chromatography (GPC) on a standard polystyrene basis. Further details are provided in the examples below.

[0023] <Vinyl chloride-vinyl acetate copolymer (A2)> Vinyl chloride-vinyl acetate copolymer (A2) is a copolymer product of vinyl chloride and vinyl acetate, and contains vinyl chloride units and vinyl acetate units. Vinyl chloride-vinyl acetate copolymer (A2) may optionally contain monomer units other than vinyl chloride units and vinyl acetate units. The other monomers are not particularly limited as long as they can copolymerize with vinyl chloride and vinyl acetate. Examples of vinyl chloride-vinyl acetate copolymers (A2) include vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-vinyl alcohol copolymers, vinyl chloride-vinyl acetate-(meth)acrylate hydroxyalkyl ester copolymers, and vinyl chloride-vinyl acetate-dicarboxylic acid copolymers. One of these may be used alone, or two or more may be used in combination. As the vinyl chloride-vinyl acetate copolymer (A2), a vinyl chloride-vinyl acetate-vinyl alcohol copolymer is preferred.

[0024] The content of vinyl chloride units relative to the total mass of the vinyl chloride-vinyl acetate copolymer (A2) is preferably 50 to 98% by mass, more preferably 70 to 98% by mass, and particularly preferably 80 to 95% by mass. When the content of vinyl chloride units is above the lower limit, the blocking resistance of the ink layer is better. When the content of vinyl chloride units is below the upper limit, the adhesion of the ink layer to the substrate and the resistance to rubbing are better.

[0025] The content of vinyl acetate units relative to the total mass of the vinyl chloride-vinyl acetate copolymer (A2) is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and particularly preferably 0.5 to 5% by mass. When the content of vinyl acetate units is above the lower limit, the adhesion of the ink layer to the substrate and the resistance to rubbing are better. When the content of vinyl acetate units is below the upper limit, the blocking resistance of the ink layer is better.

[0026] The glass transition temperature (hereinafter also referred to as Tg) of the vinyl chloride-vinyl acetate copolymer (A2) is preferably 40 to 110°C, more preferably 50 to 100°C, and particularly preferably 60 to 90°C. When the Tg of the vinyl chloride-vinyl acetate copolymer (A2) is above the lower limit, the blocking resistance, abrasion resistance, and heat resistance of the ink layer are better. When the Tg of the vinyl chloride-vinyl acetate copolymer is below the upper limit, the adhesion of the ink layer to the substrate is better. In this specification, Tg is determined in accordance with JIS K 7121, using a differential scanning calorimeter, by heating 10 mg of the sample from -100°C to 160°C at a rate of 20°C / min. The Tg is determined from the intersection of the baseline and the tangent to the endothermic curve in the resulting curve (DSC curve).

[0027] The number-average molecular weight (hereinafter also referred to as Mn) of the vinyl chloride-vinyl acetate copolymer (A2) is preferably 10,000 to 100,000, more preferably 15,000 to 80,000, and particularly preferably 20,000 to 50,000. When the Mn of the vinyl chloride-vinyl acetate copolymer (A2) is above the lower limit, the blocking resistance, abrasion resistance, and heat resistance of the ink layer are better. When the Mn of the vinyl chloride-vinyl acetate copolymer (A2) is below the upper limit, the adhesion of the ink layer to the substrate is better. In this specification, Mn is the value obtained by gel permeation chromatography (GPC) on a standard polystyrene basis.

[0028] [Matting agent (B)] The matting agent (B) contains silica (B1) with an average particle size of 2 to 10 μm and an extender pigment (B2) with an average particle size of 0.02 to 0.5 μm.

[0029] <Silica (B1)> Silica (B1) may be either naturally occurring or synthetic, and may be crystalline or amorphous. The synthesis method may be either dry or wet. Known dry methods include combustion and arc synthesis. Known wet methods include sedimentation and gel synthesis. Silica (B1) may be either hydrophobic or hydrophilic. Silica (B1) may be used alone or in combination of two or more types.

[0030] As for silica (B1), hydrophobic silica is preferred from the viewpoint of providing superior blocking resistance to the ink layer. Hydrophobic silica is silica whose surface has been treated to be hydrophobic. Hydrophobic treatment of the silica surface can be carried out by known methods using surface treatment agents. Examples of surface treatment agents include dimethyldichlorosilane, hexamethyldisilazane, octylsilane, and silicone oil. One surface treatment agent may be used alone, or two or more may be used in combination.

[0031] The average particle size of silica (B1) is 2 to 10 μm, preferably 2.5 to 8 μm, and more preferably 3 to 6 μm. When the average particle size of silica (B1) is above the lower limit, the ink layer exhibits excellent blocking resistance and matte properties. When the average particle size of silica (B1) is below the upper limit, the ink layer exhibits excellent adhesion to the substrate, transparency, abrasion resistance, and printability.

[0032] In this specification, the average particle diameter of silica is defined as the particle diameter at 50% of the volume-based cumulative value (D50) in the particle size distribution measured by laser diffraction-scattering when the average particle diameter is 100 nm or more, and as the particle diameter at 50% of the number-based cumulative value (D50) in the particle size distribution measured using a transmission electron microscope (TEM) when the average particle diameter is less than 100 nm.

[0033] <Extender pigment (B2)> The extender pigment (B2) is a solid particle formed from an inorganic material, such as barium sulfate, calcium sulfate, calcium carbonate, calcium silicate, magnesium silicate, aluminum oxide, zirconium oxide, tin oxide, clay, and kaolin. Among these, barium sulfate and calcium carbonate are preferred from the viewpoint of excellent transparency. Extender pigments (B2) may be used individually or in combination of two or more types.

[0034] The average particle size of the extender pigment (B2) is 0.02 to 0.5 μm, preferably 0.03 to 0.45 μm, and more preferably 0.04 to 0.4 μm. If the average particle size of the extender pigment (B2) is above the lower limit, the ink layer exhibits excellent blocking resistance and heat resistance. If the average particle size of the extender pigment (B2) is below the upper limit, the ink layer exhibits excellent transparency.

[0035] In this specification, the average particle size of an extender pigment 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 when 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) when the average particle size is less than 100 nm.

[0036] [Organic solvent (C)] Examples of organic solvents (C) include ketone solvents, hydrocarbon solvents, ester solvents, ether solvents, glycol ether solvents, and alcohol solvents.

[0037] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and cyclooctane. Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate. Examples of ether solvents include tetrahydrofuran, dioxane, diethyl ether, and methyl ethyl ether. Examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether. Examples of alcohol-based solvents include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; and polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin. Organic solvent (C) may be used alone or in combination of two or more types.

[0038] As for the organic solvent (C), from the viewpoint of safety in the work environment, such as odor and safety, an organic solvent that substantially does not contain aromatic hydrocarbon solvents such as toluene and xylene is preferred. The organic solvent (C) preferably includes at least one selected from the group consisting of ester-based solvents, ketone-based solvents, and alcohol-based solvents. The content of ester-based solvents in organic solvent (C) is preferably 30 to 90% by mass, based on the total amount of organic solvent (C). The content of ketone-based solvents in organic solvent (C) is preferably 0 to 50% by mass, based on the total amount of organic solvent (C). The content of alcohol-based solvents in organic solvent (C) is preferably 0 to 40% by mass, based on the total amount of organic solvent (C).

[0039] [Optional ingredients] <Hydrocarbon wax> To further improve abrasion resistance, hydrocarbon waxes can be included in the ink composition. Examples of hydrocarbon waxes include polyethylene wax, Fischer-Tropsch wax, paraffin wax, microstarin wax, and polypropylene wax. Among these, polyethylene wax and Fischer-Tropsch wax are preferred. Examples of polyethylene waxes include high-density polymerized polyethylene, low-density polymerized polyethylene, oxidized polyethylene, acid-modified polyethylene, and special monomer-modified polyethylene. Fischer-Tropsch wax is a wax produced by the Fischer-Tropsch process using carbon monoxide and hydrogen as raw materials, and has a nearly saturated, unbranched, linear molecular structure. Hydrocarbon waxes may be used individually or in combination of two or more types.

[0040] The penetration (hardness) of the hydrocarbon wax at 25°C is preferably 30 or less, more preferably 25 or less, and particularly preferably 20 or less. When the penetration (hardness) of the hydrocarbon wax is below the above upper limit, the abrasion resistance of the ink layer is better. In this specification, penetration (hardness) is a value measured in accordance with JIS K 2207.

[0041] The melting point of the hydrocarbon wax is preferably 50 to 160°C, more preferably 80 to 150°C, and particularly preferably 100 to 140°C. If the melting point of the hydrocarbon wax is above the lower limit, the heat resistance and blocking resistance are better. If the melting point of the hydrocarbon wax is below the upper limit, the abrasion resistance is better.

[0042] <Chlorinated polyolefin resin> To further improve adhesion to the substrate, the ink composition may contain chlorinated polyolefin resin. Chlorinated polyolefin resin is a polyolefin in which at least some of the hydrogen atoms are replaced by chlorine atoms. Preferred polyolefins constituting the chlorinated polyolefin resin are homopolymers or copolymers of α-olefin-based unsaturated hydrocarbons such as polypropylene, poly-1-butene, and poly-4-methyl-1-pentene, with polypropylene being more preferred. Chlorinated polyolefins may be used individually or in combination of two or more types.

[0043] The Mw of the chlorinated polyolefin resin is preferably 1,000 to 100,000, more preferably 2,000 to 80,000, and particularly preferably 3,000 to 50,000. When the Mw of the chlorinated polyolefin resin is above the lower limit, the adhesion to the substrate is better. When the Mw of the chlorinated polyolefin resin is below the upper limit, the compatibility is better.

[0044] The chlorine content of the chlorinated polyolefin resin is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, and particularly preferably 20 to 50% by mass. When the chlorine content of the chlorinated polyolefin is above the lower limit, the compatibility is better. When the chlorine content of the chlorinated polyolefin is below the upper limit, the adhesion to the substrate is better. The chlorine content of chlorinated polyolefins is the percentage (by mass) of chlorine atoms relative to the total mass of the chlorinated polyolefin.

[0045] <Resin beads> To further improve blocking resistance and matte finish, resin beads can be included in the ink composition. Examples of resin beads include melamine resins, benzoguanamine resins, (meth)acrylic resins, polystyrene resins, urethane resins, silicone resins, polycarbonate resins, copolymers of (meth)acrylic monomers and styrene monomers, polyolefin resins, polyester resins, polyamide resins, polyimide resins, and polyfluoroethylene resins. Among these, benzoguanamine resin beads are preferred from the viewpoint of excellent heat resistance. The resin beads may be crosslinked or uncrosslinked. Resin beads can be used individually or in combination of two or more types.

[0046] The average particle size of the resin beads is preferably 0.1 to 10 μm, more preferably 0.5 to 7 μm, and particularly preferably 1 to 5 μm. If the average particle size of the resin beads is above the lower limit, the ink layer exhibits superior blocking resistance, matte finish, and heat resistance. If the average particle size of the resin beads is below the upper limit, the ink layer exhibits superior abrasion resistance and printability. In this specification, the average particle size of resin beads is the particle size at 50% (D50) of the volume-based integrated value in the particle size distribution measured by laser diffraction-scattering.

[0047] <Hardening agent> To further improve adhesion to the substrate, heat resistance, and abrasion resistance, a curing agent can be included in the ink composition.

[0048] As a curing agent, isocyanate-based curing agents are preferred. An isocyanate-based curing agent is a compound having two or more isocyanate groups in one molecule. Examples of isocyanate-based curing agents include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-MDI, 2,4'-MDI, 2,4-tolylene diisocyanate (TDI), 2,6-TDI, m-xylylene diisocyanate (XDI), and 1,4-phenylene diisocyanate; isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), dicyclohexylmethane-4,4'-diisocyanate Examples include alicyclic diisocyanates such as hydrogenated MDI and 1-methylcyclohexane-2,4-diisocyanate (hydrogenated TDI); aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), and 2,4,4-trimethylhexamethylene diisocyanate; and isocyanate prepolymers such as adducts of various diisocyanates, isocyanurates of various diisocyanates, biuret compounds of HDI, and allophanates of HDI. Isocyanate-based curing agents may be used individually or in combination of two or more types.

[0049] <Other optional ingredients> Other optional components include, for example, pigments, pigment derivatives, rosin derivatives, cellulose resins, chelating agents, surfactants, anti-settling agents, UV absorbers, antioxidants, antistatic agents, leveling agents, thickeners, defoaming agents, plasticizers, dispersants, and stabilizers. These optional components may be used individually or in combination of two or more.

[0050] [Content ratio] In the ink composition, the mass ratio of the vinyl chloride-vinyl acetate copolymer (A2) to the polyhydroxypolyurethane resin (A1) on a solid content basis (A2) / (A1) (hereinafter also simply referred to as "(A2) / (A1)") is 0.1 to 0.45, preferably 0.14 to 0.4, and more preferably 0.18 to 0.35. When (A2) / (A1) is above the lower limit, the ink layer exhibits excellent blocking resistance, abrasion resistance, and heat resistance. When (A2) / (A1) is below the upper limit, the ink layer exhibits excellent adhesion to the substrate.

[0051] The mass ratio of silica (B1) to extender pigment (B2) on a solid content basis (B1) / (B2) (hereinafter also simply referred to as "(B1) / (B2)") is 0.05 to 0.5, preferably 0.06 to 0.4, and more preferably 0.1 to 0.3. When (B1) / (B2) is above the lower limit, the ink layer exhibits excellent blocking resistance and heat resistance. When (B1) / (B2) is below the upper limit, the ink layer exhibits excellent adhesion to the substrate, abrasion resistance, and printability of the ink composition.

[0052] [Content] The solid content of the binder resin (A) is preferably 20 to 55% by mass, more preferably 25 to 50% by mass, and even more preferably 30 to 40% by mass, relative to the total solid content of the ink composition. The solid content of the binder resin (A) is preferably 5 to 30% by mass, more preferably 7 to 25% by mass, and even more preferably 10 to 20% by mass, relative to the total mass of the ink composition. When the content of binder resin (A) is above the lower limit, the adhesion of the ink layer to the substrate, abrasion resistance, and printability of the ink composition are improved. When the content of binder resin (A) is below the upper limit, the blocking resistance and heat resistance of the ink layer are improved.

[0053] The content of polyhydroxypolyurethane resin (A1) on a solids basis is preferably 15 to 45% by mass, more preferably 20 to 40% by mass, and even more preferably 23 to 35% by mass, relative to the total solids of the ink composition. The content of polyhydroxypolyurethane resin (A1) on a solids basis is preferably 5 to 23% by mass, more preferably 7 to 19% by mass, and even more preferably 8 to 15% by mass, relative to the total mass of the ink composition. If the content of polyhydroxypolyurethane resin (A1) is above the lower limit, the adhesion of the ink layer to the substrate is improved. If the content of polyhydroxypolyurethane resin (A1) is below the upper limit, the blocking resistance and heat resistance of the ink layer are improved.

[0054] The content of vinyl chloride-vinyl acetate copolymer (A2) on a solids basis is preferably 4 to 10% by mass, more preferably 4.5 to 9% by mass, and even more preferably 5 to 8% by mass, relative to the total solids of the ink composition. The content of vinyl chloride-vinyl acetate copolymer (A2) on a solids basis is preferably 1 to 5% by mass, more preferably 1.5 to 4.5% by mass, and even more preferably 2 to 3% by mass, relative to the total mass of the ink composition. When the content of vinyl chloride-vinyl acetate copolymer (A2) is above the lower limit, the blocking resistance and heat resistance of the ink layer are improved. When the content of vinyl chloride-vinyl acetate copolymer (A2) is below the upper limit, the adhesion of the ink layer to the substrate is improved.

[0055] The matting agent (B), when calculated on a solids basis, is preferably 30 to 70% by mass, more preferably 40 to 65% by mass, and even more preferably 45 to 60% by mass, relative to the total solids of the ink composition. The content of matting agent (B) on a solid content basis is preferably 9 to 30% by mass, more preferably 12 to 27% by mass, and even more preferably 15 to 24% by mass, relative to the total mass of the ink composition. When the content of matting agent (B) is above the lower limit, the ink layer exhibits superior blocking resistance, matte properties, and heat resistance. When the content of matting agent (B) is below the upper limit, the ink layer exhibits superior adhesion to the substrate, transparency, abrasion resistance, and printability of the ink composition.

[0056] The silica (B1) content, calculated on a solids basis, is preferably 2.5 to 17.5% by mass, more preferably 4.5 to 15.5% by mass, and even more preferably 6.5 to 13.5% by mass, relative to the total solids of the ink composition. The silica (B1) content, calculated on a solids basis, is preferably 0.5 to 6.5% by mass, more preferably 1.5 to 5.5% by mass, and even more preferably 2.5 to 4.5% by mass, relative to the total mass of the ink composition. When the silica (B1) content is above the lower limit, the ink layer exhibits superior blocking resistance, matte finish, and heat resistance. When the silica (B1) content is below the upper limit, the ink layer exhibits superior adhesion to the substrate, transparency, abrasion resistance, and printability of the ink composition.

[0057] The content of the extender pigment (B2) on a solid content basis is preferably 26 to 52% by mass, more preferably 31 to 50% by mass, and even more preferably 36 to 48% by mass, relative to the total solid content of the ink composition. The content of the extender pigment (B2) on a solid content basis is preferably 7 to 25% by mass, more preferably 10 to 22% by mass, and even more preferably 13 to 19% by mass, relative to the total mass of the ink composition. When the content of extender pigment (B2) is above the lower limit, the ink layer exhibits superior blocking resistance, matte finish, and heat resistance. When the content of extender pigment (B2) is below the upper limit, the ink layer exhibits superior adhesion to the substrate, transparency, abrasion resistance, and printability of the ink composition.

[0058] The content of organic solvent (C) is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, and even more preferably 20 to 70% by mass, based on the total mass of the ink composition. If the content of organic solvent (C) is above the lower limit, the fluidity and printability of the ink composition will be better. If the content of organic solvent (C) is below the upper limit, the printability and storage stability of the ink composition will be better.

[0059] If the ink composition contains hydrocarbon wax, the amount of hydrocarbon wax in terms of solid content is preferably 2 to 8% by mass, more preferably 2.5 to 6.5% by mass, and even more preferably 3 to 5% by mass, relative to the total solid content of the ink composition. If the ink composition contains hydrocarbon wax, the content of hydrocarbon wax on a solids basis is preferably 0.1 to 5% by mass, more preferably 0.5 to 3.5% by mass, and even more preferably 1 to 2% by mass, relative to the total mass of the ink composition. If the hydrocarbon wax content is above the lower limit, the abrasion resistance of the ink layer is superior. If the hydrocarbon wax content is below the upper limit, the heat resistance of the ink layer is superior.

[0060] When the ink composition contains a chlorinated polyolefin resin, the content of the chlorinated polyolefin resin on a solids basis is preferably 0.1 to 4% by mass, more preferably 0.2 to 3% by mass, and even more preferably 0.4 to 2% by mass, relative to the total solids of the ink composition. When the ink composition contains a chlorinated polyolefin resin, the content of the chlorinated polyolefin resin on a solids basis is preferably 0.1 to 3% by mass, more preferably 0.1 to 2% by mass, and even more preferably 0.2 to 1% by mass, relative to the total mass of the ink composition. If the content of chlorinated polyolefin resin is above the lower limit, the adhesion of the ink layer to the substrate is superior. If the content of chlorinated polyolefin resin is below the upper limit, the heat resistance of the ink layer is superior.

[0061] If the ink composition contains resin beads, the content of resin beads in terms of solid content is preferably 0.1 to 5% by mass, more preferably 1 to 4.5% by mass, and even more preferably 2 to 4% by mass, relative to the total solid content of the ink composition. If the ink composition contains resin beads, the content of resin beads in terms of solid content is preferably 0.1 to 4% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.2 to 2% by mass, relative to the total mass of the ink composition. When the resin bead content is above the lower limit, the ink layer exhibits superior blocking resistance, matte finish, and heat resistance. When the resin bead content is below the upper limit, the ink layer exhibits superior adhesion to the substrate, transparency, abrasion resistance, and printability of the ink composition.

[0062] If the ink composition contains a curing agent, the content of the curing agent in terms of solids is preferably 0.1 to 8% by mass, more preferably 2 to 7.5% by mass, and even more preferably 4 to 7% by mass, relative to the total solids of the ink composition. If the ink composition contains a curing agent, the content of the curing agent in terms of solid content is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 1 to 3% by mass, relative to the total mass of the ink composition. When the hardening agent content is above the lower limit, the adhesion, heat resistance, and abrasion resistance of the ink layer to the substrate are improved. When the hardening agent content is below the upper limit, the blocking resistance is improved.

[0063] [Manufacturing method] The ink composition of this embodiment is obtained, for example, by dissolving or dispersing a binder resin (A), a matting agent (B), and optionally other components in an organic solvent (C). 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 the organic solvent (C) 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, 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.

[0064] [Effects and Effects] As described above, the ink composition of this embodiment contains the binder resin (A), matting agent (B), and organic solvent (C), making it possible to form an ink layer with excellent adhesion to the substrate, blocking resistance, matte finish, and transparency.

[0065] [Application] The ink composition of the present invention is printed on any substrate to form an ink layer. The ink composition of the present invention is suitable as an ink for gravure printing, and particularly for printing on flexible packaging materials by gravure printing. Here, "flexible packaging" refers to packaging materials made of flexible materials, i.e., flexible packaging, which is used for packaging food, daily necessities, and other items.

[0066] Examples of flexible packaging materials include plastic film (base film). A laminate obtained by printing on a plastic film using the ink composition of the present invention by gravure printing becomes a packaging material for flexible packaging.

[0067] Examples of plastic films include polyolefins (e.g., polyethylene (PE), polypropylene (PP), etc.), polyesters (e.g., polyethylene terephthalate (PET), etc.), polystyrene (PS), stretched polypropylene (OPP), polyamide (NY), and films made by laminating two or more of these materials. The thickness of the plastic film is not particularly limited, but is, for example, 2 to 100 μm.

[0068] Other layers may be provided between the plastic film and the ink layer formed from the ink composition of the present invention. If the ink layer formed from the ink composition of the present invention is provided on one side of the plastic film, other layers may be provided on the side of the plastic film opposite to the ink layer. Examples of other layers include printing layers formed for purposes such as decoration or information inscription. The ink layer formed from the ink composition of the present invention is preferably located on at least one surface of the laminate.

Examples

[0069] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. "Parts" means parts by mass. "%" means mass%. "NV." means solid content. Hereinafter, "polyhydroxy polyurethane resin (A1)" will also be referred to as "HPU resin (A1)". "Vinyl chloride-vinyl acetate copolymer (A2)" will also be simply referred to as "copolymer (A2)".

[0070] [Raw materials used] <HPU resin (A1), its comparative products>[ · A1-1: A polyhydroxy polyurethane resin having a hydroxyl value of 64 mgKOH / g and a Mw of 43000 obtained in Synthesis Example 1 described later. · A1-2: A polyhydroxy polyurethane resin having a hydroxyl value of 41.8 mgKOH / g and a Mw of 49000 obtained in Synthesis Example 2 described later. · A1-3: A polyhydroxy polyurethane resin having a hydroxyl value of 82 mgKOH / g and a Mw of 42000 obtained in Synthesis Example 3 described later. · A1-4: A polyhydroxy polyurethane resin having a hydroxyl value of 35 mgKOH / g and a Mw of 44000 obtained in Synthesis Example 4 described later. · A1-5: A polyhydroxy polyurethane resin having a hydroxyl value of 90 mgKOH / g and a Mw of 45000 obtained in Synthesis Example 5 described later. · A1-6: A polyurethane resin having a hydroxyl value of 4.2 mgKOH / g and a Mw of 33000. Note that A1-6 does not correspond to the polyhydroxy polyurethane resin (A1) in that it is not a reaction product of a 5-membered cyclic carbonate compound formed by the reaction of an epoxy compound and carbon dioxide and an amine compound.

[0071] (Production Example 1: Production of carbonate compound (Compound I)) In a reaction vessel equipped with a stirrer, thermometer, gas inlet tube, and reflux condenser, 100 parts of neopentyl glycol diglycidyl ether (product name: "Denacol EX-211", manufactured by Nagase ChemteX Corporation) at an epoxy equivalent weight of 138 g / eq, 100 parts of N-methyl-2-pyrrolidone (NMP), and 20 parts of sodium iodide (manufactured by Wako Pure Chemical Industries, Ltd.) were added and uniformly dissolved. Under stirring, the reaction was carried out at 100°C for 10 hours while introducing carbon dioxide (CO2 gas) at a rate of 0.5 L / min.

[0072] After the reaction was complete, 400 parts of ethyl acetate and 800 parts of water were added and the mixture was stirred for 1 hour. The ethyl acetate phase was then recovered, and the solvent was removed using an evaporator to obtain a viscous liquid compound. Using an infrared spectrophotometer (product name: "FT-720", manufactured by Horiba, Ltd., hereinafter referred to as FT-IR), the obtained viscous liquid was subjected to IR analysis, and it was found to be 910 cm³. -1 The absorption peaks originating from epoxy groups in the raw materials in the vicinity have disappeared, and a new peak has appeared at 1800 cm². -1 An absorption peak originating from a carbonate group (carbonyl group) was found in the vicinity. The obtained compound (reactant) was confirmed to be compound I, represented by the following formula, which has a cyclic carbonate group formed by the reaction of an epoxy group with carbon dioxide. The carbon dioxide content of compound I obtained above is calculated to be 24.1%.

[0073] [ka]

[0074] (Synthesis Example 1: Synthesis of A1-1) In a reaction vessel equipped with a stirrer, a refluxer with an atmospheric outlet, and a nitrogen inlet, 100 parts of Compound I obtained in Production Example 1, 18.8 parts of hexamethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 87.3 parts of a C36 dimeramine with a C6 ring structure (manufactured by Croda Japan, trade name "Priamine 1074", dimer structure ratio: 95% or more, amine value: 210 mg KOH / g), and 58.9 parts of ethyl acetate were added, and the reaction was carried out under reflux conditions at approximately 80°C for 5 hours. After the reaction, the resulting reaction solution was analyzed by FT-IR and found to be 1800 cm³. -1 The absorption originating from the carbonyl group of compound I, which had been observed nearby, has completely disappeared, and a new absorption has been found at 1760 cm⁻¹. -1 The observation of absorption originating from the carbonyl group of the urethane bond in the vicinity confirmed that a prepolymer of polyhydroxypolyurethane resin with NH2 terminals had been synthesized.

[0075] Next, without cooling the reaction solution, 21.8 parts of hexamethyldisilazane (product name: SZ-31, manufactured by Shin-Etsu Chemical Co., Ltd.) were added dropwise over 30 minutes. 30 minutes after the entire volume had been added, FT-IR measured 933 cm³ of N-Si-derived residue. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. 378.9 parts of ethyl acetate were added to the reaction solution as a diluent, and the solution was cooled to room temperature. Then, while stirring the cooled solution, 12.0 parts of isophorone diisocyanate (manufactured by Evonik Japan; the same product was used in other examples) were slowly added dropwise. After addition, FT-IR showed a reading of 2260 cm⁻¹ from the isocyanate group. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. This yielded a pale yellow, transparent polyhydroxypolyurethane resin solution with a resin content (solids) of 35%.

[0076] Regarding the obtained polyhydroxy polyurethane resin, GPC measurement was carried out using DMF (N,N-dimethylformamide) as the mobile phase. As a result, Mw was 43,000. The GPC measurement was performed using GPC-8820 (trade name, manufactured by Tosoh Corporation) for the measuring device and the following four columns. Specifically, four columns of SuperAW2500, AW3000, AW4000, and AW5000 (trade names, all manufactured by Tosoh Corporation) were used. Also, the hydroxyl value measured according to JIS-K1557-1 was 64 mgKOH / g as a solid content conversion value. In addition, in each of the following examples, Mw and the hydroxyl value were measured in the same manner as above.

[0077] (Synthesis Example 2: Synthesis of A1-2) Into a reaction vessel equipped with a stirrer, a reflux condenser with an air opening, and a nitrogen inlet tube, 100 parts of Compound I obtained in Production Example 1, 20.4 parts of hexamethylenediamine, 94.6 parts of Priamine 1074, and 65 parts of ethyl acetate were added, and the reaction was carried out for 5 hours under reflux conditions at about 80 °C. After the reaction, when the obtained reaction solution was analyzed by FT-IR, the absorption derived from the carbonyl group of Compound I observed around 1800 cm -1 completely disappeared, and newly, the absorption derived from the carbonyl group of the urethane bond was observed around 1760 cm -1 It was confirmed that a prepolymer of a polyhydroxy polyurethane resin with NH2 at the terminal was synthesized by observing the absorption derived from the carbonyl group of the urethane bond around 1760 cm.

[0078] Next, without cooling the above reaction solution, 30.5 parts of hexamethyldisilazane (product name: SZ-31) was added dropwise over 30 minutes. After 30 minutes had elapsed since the total amount was dropped, it was confirmed by FT-IR that the peak around 933 cm -1 derived from N-Si had disappeared, and the reaction was terminated. To the solution after the reaction was completed, 315.4 parts of ethyl acetate as a diluting solvent was added, and it was cooled to room temperature. Then, while stirring the cooled solution, 18.0 parts of isophorone diisocyanate was slowly added dropwise. After the dropwise addition, the absorption derived from the isocyanate group at 2260 cm -1The reaction was terminated after confirming that the nearby peaks had disappeared. This yielded a pale yellow, transparent polyhydroxypolyurethane resin solution with a resin content (solids) of 35%. The obtained polyhydroxypolyurethane resin had a Mw of 49,000. Its hydroxyl value, calculated on a solid content basis, was 41.8 mgKOH / g.

[0079] (Synthesis Example 3: Synthesis of A1-3) In a reaction vessel equipped with a stirrer, a refluxer with an atmospheric outlet, and a nitrogen inlet, 100 parts of Compound I obtained in Production Example 1, 18.8 parts of hexamethylenediamine, 87.3 parts of priamine 1074, and 58.0 parts of ethyl acetate were added, and the reaction was carried out under reflux conditions at approximately 80°C for 5 hours. After the reaction, the resulting reaction solution was analyzed by FT-IR and found to be 1800 cm³. -1 The absorption originating from the carbonyl group of compound I, which had been observed nearby, has completely disappeared, and a new absorption of 1760 cm⁻¹ has been detected. -1 The observation of absorption originating from the carbonyl group of the urethane bond in the vicinity confirmed that a prepolymer of polyhydroxypolyurethane resin with NH2 terminals had been synthesized.

[0080] Next, without cooling the reaction solution, 17.4 parts of hexamethyldisilazane (product name: SZ-31) were added dropwise over 30 minutes. 30 minutes after the total amount had been added, FT-IR measured 933 cm³ of N-Si-derived residue. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. 372.6 parts of ethyl acetate were added to the reaction solution as a diluent, and the solution was cooled to room temperature. Then, 12.0 parts of isophorone diisocyanate were slowly added dropwise while stirring the cooled solution. After the addition, FT-IR measured a 2260 cm⁻¹ peak originating from the isocyanate group. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. This yielded a pale yellow, transparent polyhydroxypolyurethane resin solution with a resin content (solids) of 35%. The obtained polyhydroxypolyurethane resin had a Mw of 42,000. Its hydroxyl value, calculated on a solid content basis, was 82 mgKOH / g.

[0081] (Synthesis Example 4: Synthesis of A1-4) In a reaction vessel equipped with a stirrer, a refluxer with an atmospheric outlet, and a nitrogen inlet, 100 parts of Compound I obtained in Production Example 1, 20.2 parts of hexamethylenediamine, 99.1 parts of priamine 1074, and 68.6 parts of ethyl acetate were added, and the reaction was carried out under reflux conditions at approximately 80°C for 5 hours. After the reaction, the resulting reaction solution was analyzed by FT-IR and found to be 1800 cm³. -1 The absorption originating from the carbonyl group of compound I, which had been observed nearby, has completely disappeared, and a new absorption of 1760 cm⁻¹ has been detected. -1 The observation of absorption originating from the carbonyl group of the urethane bond in the vicinity confirmed that a prepolymer of polyhydroxypolyurethane resin with NH2 terminals had been synthesized.

[0082] Next, without cooling the reaction solution, 36.5 parts of hexamethyldisilazane (product name: SZ-31) were added dropwise over 30 minutes. 30 minutes after the total amount had been added, FT-IR measured 933 cm³ of N-Si-derived residue. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. 434.9 parts of ethyl acetate were added to the reaction solution as a diluent, and the solution was cooled to room temperature. Then, 19.0 parts of isophorone diisocyanate were slowly added dropwise while stirring the cooled solution. After the addition, FT-IR showed a value of 2260 cm⁻¹ derived from the isocyanate group. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. This yielded a pale yellow, transparent polyhydroxypolyurethane resin solution with a resin content (solids) of 35%. The obtained polyhydroxypolyurethane resin had a Mw of 44,000. Its hydroxyl value, calculated on a solid content basis, was 35 mg KOH / g.

[0083] (Synthesis Example 5: Synthesis of A1-5) In a reaction vessel equipped with a stirrer, a refluxer with an atmospheric outlet, and a nitrogen inlet, 100 parts of Compound I obtained in Production Example 1, 20.2 parts of hexamethylenediamine, 99.1 parts of priamine 1074, and 63.6 parts of ethyl acetate were added, and the reaction was carried out under reflux conditions at approximately 80°C for 5 hours. After the reaction, the resulting reaction solution was analyzed by FT-IR and found to be 1800 cm³. -1 The absorption originating from the carbonyl group of compound I, which had been observed nearby, has completely disappeared, and a new absorption of 1760 cm⁻¹ has been detected. -1 The observation of absorption originating from the carbonyl group of the urethane bond in the vicinity confirmed that a prepolymer of polyhydroxypolyurethane resin with NH2 terminals had been synthesized.

[0084] Next, without cooling the reaction solution, 14.0 parts of hexamethyldisilazane (product name: SZ-31) were added dropwise over 30 minutes. 30 minutes after the total amount had been added, FT-IR measured 933 cm³ of N-Si-derived residue. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. 402.5 parts of ethyl acetate were added to the reaction solution as a diluent, and the solution was cooled to room temperature. Then, 19.0 parts of isophorone diisocyanate were slowly added dropwise while stirring the cooled solution. After the addition, FT-IR showed a 2260 cm⁻¹ peak originating from the isocyanate group. -1 The reaction was terminated after confirming that the nearby peaks had disappeared. This yielded a pale yellow, transparent polyhydroxypolyurethane resin solution with a resin content (solids) of 35%. The obtained polyhydroxypolyurethane resin had a Mw of 45,000. Its hydroxyl value, calculated on a solid content basis, was 90 mgKOH / g.

[0085] <Copolymer (A2)> A2-1: Vinyl chloride-vinyl acetate copolymer (vinyl chloride units: vinyl acetate units: vinyl alcohol units = 87.5:1:11.5 (mass ratio), Tg 75℃, Mn 29000). A2-2: Vinyl chloride-vinyl acetate copolymer (vinyl chloride units: vinyl acetate units: vinyl alcohol units = 91.5:3:5.5 (mass ratio), Tg 74℃, Mn 35000).

[0086] <Silica (B1)> B1-1: Silohobic 200 (manufactured by Fuji Silicia Chemical Co., Ltd., hydrophobic silica, average particle size 3.9 μm). B1-2: Silohobic 4004 (manufactured by Fuji Silicia Chemical Co., Ltd., hydrophobic silica, average particle size 8 μm). • B1-3: Silicea 350 (manufactured by Fuji Silicea Chemical Co., Ltd., hydrophilic silica, average particle size 3.9 μm). B1-4: Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, average particle size 16 nm). • B1-5: NIP Gel AY-603 (manufactured by Tosoh Silica Co., Ltd., hydrophilic silica, average particle size 10.8 μm).

[0087] <Extender pigment (B2)> • B2-1: Varifine BF10 (manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate, average particle size 0.06 μm). · B2-2: Varifine BF20 (manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate, average particle size 0.03 μm). ·B2-3: Variace B-34 (manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate, average particle size 0.3 μm). B2-4: Shirotsuyahana DD (manufactured by Shiraishi Calcium Co., Ltd., calcium carbonate, average particle size 0.1 μm). • B2-5: Varifine BF40 (manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate, average particle size 0.01 μm). • B2-6: Precipitated Barium Sulfate 100 (manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate, average particle size 0.6 μm).

[0088] <Organic solvent (C)> A mixed solvent of n-propyl acetate and isopropanol in a 2:1 (mass ratio).

[0089] <Optional ingredients> • Wax: Manufactured by Mitsui Chemicals, Inc., product name "High Wax 220P", melting point 110℃, penetration degree 13. • Chlorinated polyolefin resin: Manufactured by Nippon Paper Industries Co., Ltd., product name "Superclon 814HS", chlorine content 41%. • Resin beads: Manufactured by Nippon Shokubai Co., Ltd., product name "Epostor MS", benzoquanamine-formaldehyde condensate, average particle size 2 μm. • Hardener: Hexamethylene diisocyanate.

[0090] [Examples 1-21, Comparative Examples 1-11] <Preparation of Ink Composition> HPU resin (A1) or a comparable product thereof, copolymer (A2), silica (B1), extender pigment (B2), organic solvent (C), and other optional components were mixed according to the compositions shown in Tables 1 to 5, and the resulting mixture was kneaded in a paint shaker to obtain an ink composition. In Tables 1-5, the content of each component is expressed as a percentage (%) of the total mass of the ink composition. The content of components other than organic solvent (C) is expressed on a solids basis. The "residue" of organic solvent (C) is the amount that makes the sum of all components (total mass of the ink composition) 100%.

[0091] <Creating printed materials> The prepared ink composition was diluted with a mixed solvent of n-propyl acetate:isopropanol = 2:1 (mass ratio) so that the viscosity at 20°C, as measured using a Zahn cup #3, was 17 seconds, to prepare a printing ink. Using a gravure printing press (manufactured by Matsuo Sangyo Co., Ltd., product name "K Printing Proofer") equipped with a Helio 175 lines / inch gravure engraving plate, the prepared printing ink was applied to the untreated side of a PET film (manufactured by Toyobo Co., Ltd., product name "E5102", thickness: 25 μm) with one side corona discharge treated, or to the treated side of an OPP film (manufactured by Futamura Chemical Co., Ltd., product name "FOR", thickness: 25 μm) with one side corona discharge treated. After that, the prints were aged at 40°C for 48 hours to obtain the printed material.

[0092] The following evaluations were conducted on the printed materials or ink compositions. The results are shown in Tables 1-5. Unless otherwise specified, the evaluation of printed materials was performed on materials after aging. Hereafter, printed materials with a PET film base will also be referred to as "printed materials (PET)," and printed materials with an OPP film base will also be referred to as "printed materials (OPP)."

[0093] <Evaluation of adhesion to the substrate> After applying cellophane tape (manufactured by Nichiban Co., Ltd.) to the printed surface of printed materials (PET) and printed materials (OPP), the cellophane tape was promptly removed, and the condition of the printed layer remaining on the base film was visually inspected. The adhesion to the base material was evaluated according to the evaluation criteria shown below. A score of 3 to 5 was considered acceptable. 5. The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is less than 5%. 4. The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is 5% or more and less than 20%. 3. The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is 20% or more and less than 50%. 2: The ratio of the area of ​​the peeled-off printed layer to the total area of ​​the printed layer is 50% or more and less than 80%. 1: The area of ​​the peeled-off printed layer is 80% or more of the total area of ​​the printed layer.

[0094] <Evaluation of blocking resistance> The printed layer of a printed material (PET) before aging is placed on top of the unprinted side of the same printed material (PET), and the aging process is performed at 4 kg / cm². 2 The samples were subjected to a load and stored in a 40°C constant temperature chamber for 24 hours. Afterward, the overlapping printed layers were peeled off, and their blocking resistance was evaluated according to the criteria shown below. A score of 3 to 5 was considered acceptable. 5. Ink removal to the non-printed surface is less than 5% of the total area of ​​the printed layer. 4. Ink removal to the non-printed surface is between 5% and 20% of the total printed area. 3. Ink removal to the non-printed surface is between 20% and 50% of the total printed surface area. 2: Ink removal to the non-printed surface is between 50% and 80% of the total printed surface area. 1: Ink removal to the non-printed surface is 80% or more of the total area of ​​the printed layer.

[0095] <60° Gross Evaluation> A printed material (PET) was placed on the black side of an opacity test paper (manufactured by TP Giken Co., Ltd.) with the printed side facing upwards, and the 60° gloss was measured using a gloss meter (manufactured by BYK Gardner, product name "micro-TRI-gloss"). A lower 60° gloss value indicates a better matte finish. A 60° gloss of 15 or less was considered acceptable.

[0096] <L * Value evaluation > Place the printed material (PET) on the black side of the opacity test paper (manufactured by TP Giken Co., Ltd.) with the printed side facing upwards, and use a colorimeter (manufactured by x-rite, product name "exact") to measure the L * The value was measured. L * A lower value indicates less whiteness and better transparency. * A value of 50 or less was considered acceptable.

[0097] <Evaluation of abrasion resistance> The printed surface of the printed material (PET) was subjected to a friction test using a JSPS-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which a black cloth (cotton 3-1: metal cloth 3) with a load of 200 gf was rubbed back and forth 100 times. Afterwards, the appearance of the ink layer was visually inspected, and the friction resistance was evaluated according to the evaluation criteria shown below. A score of 3 to 5 was considered acceptable. 5. The percentage of the ink layer that has migrated to the black cloth (gold cloth No. 3) is between 0% and 10%. 4. The percentage of the ink layer that has migrated to the black cloth (gold cloth No. 3) side is 10% or more and less than 20%. 3. The percentage of the ink layer that has migrated to the black cloth (gold cloth No. 3) is 20% or more and less than 50%. 2: The percentage of the ink layer area that has migrated to the black cloth (gold cloth No. 3) side is 50% or more and less than 80%. 1: The area of ​​the ink layer that has migrated to the black cloth (gold cloth No. 3) is between 80% and 100%.

[0098] <Evaluation of printability> The prepared ink composition was diluted with a mixed solvent of n-propyl acetate:isopropanol = 2:1 (mass ratio) so that the viscosity at 20°C, as measured using a Zahn cup #3, was 17 seconds. The diluted ink composition was supplied to the ink pan of a 5-color gravure printing press (manufactured by Fuji Machinery Industry Co., Ltd.) equipped with a commercially available steel doctor blade and a plate with only the non-image area, and the plate was run idle for 30 minutes at a rate of 150 m / min. After that, streaky stains (doctor blade streaks) that appeared on the plate surface were visually inspected, and the printability was evaluated according to the evaluation criteria shown below. A score of 3 to 5 was considered acceptable. 5: No or very faint doctor's muscle was observed, or 1-2 very faint doctor's muscles were found. 4: Three to five thin muscle fibers were identified. 3: Six or more thin doctor's muscles, or one or two thick doctor's muscles were identified. 2: Three to five thick muscle fibers were observed. 1: More than six thick, defined muscle fibers were observed.

[0099] [Table 1]

[0100] [Table 2]

[0101] [Table 3]

[0102] [Table 4]

[0103] [Table 5] [Industrial applicability]

[0104] The ink composition of the present invention is capable of forming an ink layer with excellent adhesion to the substrate, blocking resistance, matte finish, and transparency, and is useful as an ink for gravure printing.

Claims

1. An ink composition containing a binder resin (A), a matting agent (B), and an organic solvent (C), The binder resin (A) is a reaction product of a five-membered cyclic carbonate compound formed by the reaction of an epoxy compound and carbon dioxide, and an amine compound, and contains a polyhydroxypolyurethane resin (A1) having a hydroxyl value of 40 to 85 mg KOH / g, and a vinyl chloride-vinyl acetate copolymer (A2). The matting agent (B) contains silica (B1) with an average particle size of 2 to 10 μm and an extender pigment (B2) with an average particle size of 0.02 to 0.5 μm. The mass ratio (A2) / (A1) of the polyhydroxypolyurethane resin (A1) on a solid content basis is 0.1 to 0.

45. An ink composition characterized in that the mass ratio (B1) / (B2) of silica (B1) to the extender pigment (B2) on a solid content basis is 0.05 to 0.

5.

2. The ink composition according to claim 1, wherein the content of the binder resin (A) on a solid content basis is 25 to 50% by mass relative to the total solid content of the ink composition.

3. The ink composition according to claim 1, wherein the content of the matting agent (B) on a solid content basis is 36 to 61.5% by mass relative to the total solid content of the ink composition.

4. The ink composition according to claim 1, wherein the silica (B1) is hydrophobic silica.

5. Furthermore, the ink composition according to claim 1, further containing a hydrocarbon wax.

6. Furthermore, the ink composition according to claim 1 further contains a chlorinated polyolefin resin.

7. Furthermore, the ink composition according to claim 1, further comprising resin beads.

8. Furthermore, the ink composition according to claim 1, further containing a curing agent.

9. An ink composition according to any one of claims 1 to 8, for use in gravure printing.

10. A laminate comprising a plastic film and an ink layer provided on the plastic film, wherein the ink layer is a layer formed from the ink composition described in claim 9.

11. A packaging material comprising the laminate described in claim 10.

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