Coating agent for printing, and printed substrate, container and packaging material having a coating layer of said coating agent

Abstract

To provide a coating agent for printing that excels in adhesion to printed materials, particularly a digital printed material, in blocking resistance to plastic such as polyvinyl chloride for use as a substrate, and in alcohol resistance.SOLUTION: This invention relates to a coating agent for printing that contains a polyvinyl chloride copolymer resin and an acrylic resin as main binder resins and also contains an organic solvent, the coating agent satisfying the following items: (1) a plasticizer is contained at a rate of 1.0-10.0 mass% to the total solid content of the coating agent; and (2) a chelate compound is contained at a rate of 0.03-10.0 mass% to the total solid content of the coating agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to printing coatings and printed substrates, containers and packaging materials. [Background technology]

[0002] BACKGROUND ART Conventionally, printed matter used in various packaging materials has been coated with a colorless and transparent printing coating agent after printing for the purpose of improving the gloss of the printed matter or protecting the film of the printed matter.

[0003] Methods for printing printing inks or printing coatings onto plastic film substrates or paper substrates that serve as the base material for various packaging materials include gravure printing, flexographic printing, digital printing, etc. Printing coatings are required to have adhesion to these printing inks, blocking resistance to plastics such as polyvinyl chloride used as the base material, and alcohol resistance, which has become essential in recent years from the perspective of hygiene, for use in sterilization and disinfection (particularly abrasion resistance when the packaging material itself is wiped with a cloth or paper soaked in alcohol).

[0004] In particular, a printing coating agent containing a specific polyurethane resin, a vinyl chloride-vinyl acetate copolymer resin, and a rosin-modified maleic acid resin is known as a printing coating agent suitable for digital printing (see, for example, Patent Document 1). This printing coating agent has excellent physical properties such as scratch resistance, tape adhesion resistance, heat resistance, and gloss, as well as blocking resistance to PVC sheets, but there is no mention of alcohol resistance, which has been in high demand in recent years. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-145283 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a coating agent for printing that has excellent adhesion to digitally printed matter, blocking resistance to plastics such as vinyl chloride used as a substrate, and alcohol resistance. [Means for solving the problem]

[0007] That is, the present invention provides a printing coating agent that contains a vinyl chloride copolymer resin and an acrylic resin as main binder resins and an organic solvent, and that satisfies the following requirements: (1) The coating agent contains a plasticizer in an amount of 1.0 to 10.0% by mass based on the total solid content of the coating agent. (2) The coating agent contains a chelate compound in an amount of 0.03 to 10.0% by mass based on the total solid content of the coating agent.

[0008] The present invention also provides a coating agent for printing, wherein the chelate compound is a titanium-based chelate compound.

[0009] The present invention also provides a coating agent for printing, which contains 0.15 to 10.0% by mass of wax relative to the total solid content of the coating agent.

[0010] The present invention also provides a printing coating agent for use in digital printing.

[0011] The present invention also provides a printed substrate obtained by coating a printed substrate with the above-described coating agent for printing.

[0012] The present invention also provides a printed substrate obtained by coating a digitally printed substrate with the above-described coating agent for printing.

[0013] The present invention also provides containers and packaging materials using the above-described printed substrate. [Effects of the Invention]

[0014] The present invention can provide a coating agent for printing that has excellent adhesion to digitally printed matter, blocking resistance to plastics such as vinyl chloride used as a substrate, and alcohol resistance. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Definition of words) In the present invention, all "parts" refer to "parts by mass," "total amount of coating agent" refers to the total amount of ink including all volatile components such as organic solvents, and "total amount of solids in coating agent" refers to the total amount of only non-volatile components, excluding volatile components.

[0016] (Binder resin (A)) The binder resin used in the present invention is mainly a vinyl chloride copolymer resin and an acrylic resin. In addition, rosin-based resins, cellulose-based resins such as nitrocellulose, cellulose acetate propionate (CAP), and cellulose acetate butyronate (CAB), polyurethane-based resins, polyester resins, chlorinated polypropylene resins, vinyl-based resins, and the like may be appropriately contained within a range that does not impair the effects of the present invention.

[0017] (Vinyl chloride copolymer resin) As the vinyl chloride copolymer resin, any known resin can be used without any particular limitation, but in the present invention, it is preferable to use a vinyl chloride-vinyl acetate copolymer resin or a vinyl chloride-vinyl isobutyl ether copolymer resin.

[0018] (Vinyl chloride-vinyl acetate copolymer resin) The vinyl chloride-vinyl acetate copolymer resin used in the present invention is not particularly limited as long as it is a copolymer of vinyl chloride and vinyl acetate. The molecular weight is preferably a weight-average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000. Of 100% by mass of the solids content of the vinyl chloride-vinyl acetate copolymer resin, the vinyl acetate monomer-derived structure is preferably 5 to 30% by mass, and the vinyl chloride monomer-derived structure is preferably 70 to 95% by mass. This improves solubility in organic solvents, and further improves adhesion to substrates, coating properties, scratch resistance, etc. From the viewpoint of solubility in organic solvents, those containing hydroxyl groups derived from a vinyl alcohol structure are also preferred. The hydroxyl value is preferably 20 to 200 mgKOH / g. The glass transition temperature is preferably 50 to 90°C. The amount of vinyl chloride-vinyl acetate copolymer resin added is 10.0 to 40.0 mass % of the coating agent solid content, and preferably 15.0 to 25.0 mass %. Vinyl chloride-vinyl acetate copolymer resin particularly contributes to coating film formation, so adding it in this range is particularly effective.

[0019] (Vinyl chloride-vinyl isobutyl ether copolymer resin) The vinyl chloride-vinyl isobutyl ether copolymer resin used in the present invention is not particularly limited as long as it is a copolymer of vinyl chloride and vinyl isobutyl ether. The weight average molecular weight is preferably 5,000 to 100,000, and more preferably 10,000 to 70,000. In 100% by mass of the solid content of the vinyl chloride-vinyl isobutyl ether copolymer resin, the vinyl isobutyl ether-derived structure is preferably 1 to 30% by mass, and the vinyl chloride monomer-derived structure is preferably 70 to 99% by mass. The amount of vinyl chloride-vinyl isobutyl ether copolymer resin added is 10.0 to 40.0 mass% of the coating agent solid content as described above, but is preferably 15.0 to 23.0 mass%. Vinyl chloride-vinyl isobutyl ether copolymer resin particularly contributes to coating film formation, and adding it within this range is particularly effective.

[0020] (acrylic resin) The acrylic resin is not particularly limited as long as it is a copolymer of a polymerizable monomer mainly composed of a (meth)acrylic acid ester. Examples of the polymerizable monomer include alkyl ester compounds of (meth)acrylic acid such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate; (meth)acrylic acid amide derivatives containing at least one N-substituted methylol group such as N-methylol (meth)acrylamide; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dipropylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate. Examples of the polymerizable monomer include (meth)acrylate, aminoalkyl esters of (meth)acrylic acid such as diethylaminopropyl (meth)acrylate and dipropylaminopropyl (meth)acrylate, mono- or diesters of (meth)acrylic acid of glycols such as diethylene glycol and dipropylene glycol, styrene derivatives such as styrene and α-methylstyrene, hydroxyalkyl ester compounds of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate, and vinyl compounds having an acid group such as acrylic acid, methacrylic acid, maleic acid and itaconic acid. The polymerization method is not particularly limited, and those obtained by known methods such as bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization can be used. The weight average molecular weight of the acrylic resin is preferably 5,000 to 200,000, and more preferably in the range of 10,000 to 100,000. The amount of acrylic resin added is 50.0 to 80.0 mass % of the coating agent solid content, and preferably 65.0 to 75.0 mass %. The acrylic resin particularly contributes to heat resistance and alcohol resistance, and adding it within this range is particularly effective.

[0021] (rosin-based resin) The rosin resin used in the present invention is not particularly limited as long as it has an acid value of 190 mgKOH / g or less and a softening point of 160°C or less, and rosin and / or rosin derivatives commonly used for printing inks can be used. Specific examples of rosin or rosin derivatives include rosins or carboxyl group-containing derivatives thereof. Examples of rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, and polymers thereof. Examples of rosin derivatives include carboxyl group-containing derivatives such as rosin derivatives to which unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, and crotonic acid have been added. The acid value of the rosin-based resin is preferably 100 mgKOH / g or less, and more preferably 50 mgKOH / g or less. There is no particular lower limit, but any acid value of 20 mgKOH / g or more can be used without any particular limitation.

[0022] In the present invention, it is preferable to use a rosin-modified maleic acid resin, which is a maleic acid derivative of rosin, or a rosin-modified fumaric acid resin, which is a fumaric acid derivative of rosin. The rosin-modified maleic acid resin or rosin-modified fumaric acid resin used in the present invention is not particularly limited, and any known rosin-modified maleic acid resin or rosin-modified fumaric acid resin can be used. The rosin-modified maleic acid resin or rosin-modified fumaric acid resin preferably has an acid value of 25 mgKOH / g or more and 320 mgKOH / g or less, and particularly preferably has an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less. The amount of rosin resin added is preferably 0.7 to 4.5 mass % relative to the solid content of the coating agent, and more preferably 1.5 to 3.0 mass %.

[0023] Examples of commercially available rosin-based resins include Marquid Nos. 1, 2, 5, 6, 8, 31, 32, 33, 34, and 3002 manufactured by Arakawa Chemical Industries, Ltd., and Harimac R-80, T-80, R-100, M-453, M-130A, 135GN, 145P, and R-120AH, and Haritac 4851, 4821, 4740, and 28JA manufactured by Harima Chemicals Co., Ltd.

[0024] In the present invention, there are no particular limitations on the binder resins used, other than the incorporation of the vinyl chloride-vinyl acetate copolymer resin, the acrylic resin, the vinyl chloride-vinyl isobutyl ether copolymer resin, and the rosin-based resin in predetermined amounts, and known binder resins can also be used in combination. Examples of such binder resins include cellulose-based resins such as soluble nitrocellulose, cellulose acetate propionate (CAP), and cellulose acetate butyronate (CAB), polyurethane resins, polyamide-based resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, and polyvinyl chloride resins, polyester resins, alkyd resins, ketone resins, cyclized rubber, chlorinated rubber, butyral, and petroleum resins.

[0025] (cellulose resin) Examples of cellulose-based resins include cellulose acetate propionate, cellulose acetate butyrate, and other cellulose ester resins, nitrocellulose (also known as soluble cellulose), hydroxyalkyl cellulose, and carboxyalkyl cellulose. The cellulose ester resin preferably has an alkyl group, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, and a hexyl group, and the alkyl group may further have a substituent. Of the above, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred as cellulose-based resins. Nitrocellulose is particularly preferred. The weight-average molecular weight is preferably 5,000 to 200,000, and more preferably 10,000 to 50,000. Furthermore, the glass transition temperature is preferably 120°C to 180°C. When polyurethane resin is used in combination, improvements in blocking resistance, scratch resistance, and other physical properties of the ink film can be expected. Nitrocellulose (nitrocellulose) is preferably obtained as a nitric acid ester by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydroglucopyranose group in the natural cellulose with nitric acid groups.

[0026] The use of nitrocellulose (nitrocellulose) provides high dispersibility in pigments, and is therefore suitable for use as a coating agent for surface printing, as it can improve the strength of the printing ink film. The nitrocellulose (nitrocellulose) preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 30 to 500, and more preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 45 to 290.

[0027] The amount of nitrocellulose (nitrocellulose) added is 10.0 to 25.0% by mass, preferably 15.0 to 20.0% by mass, based on the solid content of the coating agent.

[0028] (Polyurethane resin) The polyurethane resin is not particularly limited as long as it is a polyurethane resin obtained by reacting a polyol with a polyisocyanate. Examples of polyols that can be used include various known polyols that are commonly used in the production of polyurethane resins, and one or more of these may be used in combination. Examples of suitable polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, and dipropylene glycol. Saturated or unsaturated low molecular weight polyols (1) such as ethylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, and pentaerythritol; these low molecular weight polyols (1) and sebacic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, and trimellitic acid. polyester polyols (2) obtained by dehydration condensation or polymerization of polycarboxylic acids such as methyl acrylate, pyromellitic acid, or their anhydrides; polyester polyols (3) obtained by ring-opening polymerization of cyclic ester compounds, for example, lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone); polycarbonate polyols (4) obtained by reacting the low-molecular-weight polyols (1) or the like with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like; polybutadiene glycols (5); glycols (6) obtained by adding ethylene oxide or propylene oxide to bisphenol A; and acrylic polyols (7) obtained by copolymerizing, in one molecule, one or more hydroxyethyl groups, hydroxypropyl acrylate, hydroxybutyl acrylate, or the like, or the corresponding methacrylic acid derivatives, with, for example, acrylic acid, methacrylic acid, or an ester thereof.

[0029] Examples of polyisocyanates include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates that are generally used in the production of polyurethane resins. For example, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzene Aromatic polyisocyanates such as zenediisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-diisocyanate, 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3-3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, and diphenylmethane-2,4-diisocyanate;Aliphatic or alicyclic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatomethyl)cyclohexane, 1,4-di(isocyanatomethyl)cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, and 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more. Among these, these diisocyanate compounds can be used alone or in combination of two or more.

[0030] Chain extenders can also be used. Examples of chain extenders include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, and dicyclohexylmethane-4,4'-diamine, as well as amines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These chain extenders can be used alone or in combination of two or more.

[0031] Monovalent active hydrogen compounds can also be used as end-capping agents for the purpose of terminating the reaction. Examples of such compounds include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol. Furthermore, when it is particularly desired to introduce carboxyl groups into the polyurethane resin, amino acids such as glycine and L-alanine can be used as reaction terminators. These end-capping agents can be used alone or in combination. The weight average molecular weight of the polyurethane resin is preferably 10,000 to 100,000, and more preferably in the range of 15,000 to 80,000. The amount of polyurethane resin added is preferably 10.0 to 80.0% by mass, and more preferably 15.0 to 50.0% by mass, based on the total amount of ink.

[0032] (polyester resin) The polyester resin is not particularly limited as long as it is a polyester resin obtained by reacting an alcohol with a carboxylic acid using a known esterification polymerization reaction. Examples of alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, and isosorbide. These may be used alone or in combination of two or more. Among these, polyfunctional alcohols are preferred. Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, linoleic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and 1,4-cyclohexanedicarboxylic acid. These may be used alone or in combination of two or more. Among these, polyfunctional carboxylic acids are preferred. The weight average molecular weight of the polyester resin is preferably 500 to 6000, more preferably 1400 to 5500. The amount of polyester resin added is preferably 0.15 to 40% by mass, and more preferably 1.0 to 35% by mass, based on the total amount of ink.

[0033] (chlorinated polyolefin resin) The chlorinated polyolefin resin used in the present invention is not particularly limited as long as it is a polyolefin resin in which at least a portion of the hydrogen atoms are substituted with chlorine atoms. The weight-average molecular weight of the chlorinated polyolefin is preferably 5,000 to 100,000, more preferably 5,000 to 70,000, and even more preferably 7,000 to 50,000. Furthermore, in order to improve adhesion to substrates, the chlorine content of the chlorinated polyolefin resin is preferably 25 to 45% by mass. Furthermore, from the viewpoint of solubility in organic solvents, the chlorine content is more preferably 26 to 43% by mass. Here, the chlorine content refers to the mass % content of chlorine atoms in 100% by mass of the chlorinated polyolefin resin. Furthermore, from the viewpoint of a balance with blocking resistance, the chlorinated polyolefin resin is contained in the coating agent solids at 1.0 to 10.0% by mass, preferably 1.5 to 4.5% by mass.

[0034] Chlorinated polyolefin resins have flexible alkyl groups in a branched structure, making them flexible even at low temperatures and contributing to improved substrate adhesion. The structure of the polyolefin resin in the chlorinated polyolefin resin is not particularly limited. For example, resins containing homopolymers or copolymers of α-olefin-based unsaturated hydrocarbons such as polypropylene, poly-1-butene, and poly-4-methyl-1-pentene are preferred. Among these, chlorinated polypropylene resins containing a polypropylene structure (i.e., a chlorinated polypropylene structure) are particularly preferred.

[0035] (vinyl resin) Furthermore, vinyl resins other than the vinyl chloride-vinyl acetate copolymer resin and vinyl chloride-vinyl isobutyl ether copolymer resin may also be used. Examples of the vinyl chloride resins include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer, vinyl chloride-acrylonitrile copolymer, and vinyl chloride-various vinyl ether copolymers, as well as blends thereof and other chlorine-free synthetic resins such as acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl (meth)acrylate copolymer, blends with polyesters, block copolymers, graft copolymers, and the like. These vinyl chloride resins may be a mixture of two or more kinds, or may be a mixture with other synthetic resins.

[0036] Vinyl acetate resins are vinyl acetate monomers alone or copolymers of vinyl acetate monomers with polymerizable unsaturated monomers. Examples of unsaturated monomers include long-chain (meth)acrylic monomers such as alkyl (meth)acrylate monomers (e.g., n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate), hydroxyl group-containing (meth)acrylic monomers such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, and (poly)ethylene glycol mono(meth)acrylate, carboxyl group-containing monomers (e.g., (meth)acrylic acid, maleic acid, and maleic anhydride), vinyl monomers (e.g., styrene, acrylonitrile, and vinyl chloride), and ethylene. These may be used alone or in combination of two or more.

[0037] The weight average molecular weight of the vinyl resin is preferably 5,000 to 100,000, more preferably 10,000 to 70,000. The amount of vinyl resin added is 5.0 to 40.0% by mass, preferably 10.0 to 25.0% by mass, based on the solid content of the coating agent.

[0038] (hardening agent) Furthermore, a curing agent such as an isocyanate may be used in the binder resin. The amount of the isocyanate compound added is preferably in the range of 0.3 to 10.0% by mass, more preferably 1.0 to 7.0% by mass, based on the solid content of the liquid printing coating agent, from the viewpoint of curing efficiency. The total amount of binder resin is preferably in the range of 0.15 to 50% by mass, and most preferably in the range of 1 to 40% by mass, based on the solid content of the coating agent.

[0039] (plasticizer) The present invention is characterized in that the coating agent contains a plasticizer in an amount of 1.0 to 10.0 mass % based on the total solid content of the coating agent. By including a plasticizer, thickening of the coating agent can be suppressed, and the softness and flexibility of the dried coating film can be maintained. Examples of plasticizers include fatty oils such as castor oil, phthalate ester plasticizers such as dioctyl phthalate, phosphate ester plasticizers, fatty acid ester plasticizers such as adipate ester plasticizers and sebacate ester plasticizers, polyester plasticizers, epoxy plasticizers such as epoxidized vegetable oil, citrate ester plasticizers such as acetyl tributyl citrate, and sulfonate amide plasticizers such as N-butylbenzenesulfonamide and N-ethyltoluenesulfonamide. Among these, citrate esters, epoxidized vegetable oils, phosphate ester plasticizers, and sulfonate amide plasticizers are preferred. Sulfonate amide plasticizers are the most preferred. The amount of the plasticizer is preferably in the range of 1.0 to 10.0% by mass, and most preferably in the range of 3.0 to 7.0% by mass, based on the solid content of the coating agent. These plasticizers may be used alone or in combination.

[0040] (Chelate compounds) The present invention is characterized in that the chelate compound is contained in an amount of 0.03 to 10.0% by mass relative to the solid content of the coating agent. By containing the chelate compound in this range, a balance with the rosin-based resin added to contribute to biomass is achieved, resulting in an ink with improved lamination strength and ink offset.

[0041] The chelate compound is preferably a metal chelate compound. As the metal chelate compound, a titanium-based chelate compound, a zirconium-based chelate compound, or an aluminum-based chelate compound can be used. Among them, a titanium-based chelate compound is preferred. Titanium-based chelate compounds are classified into alkoxides, acylates, and chelate complexes, but the chelate compounds used in the present invention are more preferably chelate complexes than alkoxides or acylates. Specific examples of chelate complexes include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, and phosphate ester titanium complexes. The titanium ethylacetoacetate and phosphate ester titanium complexes are acetylacetone-free and therefore have a higher level of safety. Among these, titanium chelate complexes are preferred. The content is more preferably 0.03 to 10.0 mass % relative to the solid content of the coating agent, and most preferably 1.5 to 6.5 mass %.

[0042] (wax) The coating agent of the present invention preferably contains 0.15 to 10.0 mass % of hydrocarbon wax relative to the solid content of the coating agent. The carbon wax is preferably a polyolefin wax or a Fischer-Tropsch wax. Examples of the polyolefin wax include polyethylene wax and polypropylene wax. Among these, polyethylene wax is preferred.

[0043] (organic solvent) The organic solvent used in the coating agent of the present invention is not particularly limited and may be any organic solvent used in the field of printing inks. Examples include aromatic hydrocarbon organic solvents such as toluene, xylene, Solvesso #100, Solvesso #150, etc., aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, decane, etc., and various ester organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, etc. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; glycol ethers such as ethylene glycol (mono- and di-)methyl ether, ethylene glycol (mono- and di-)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono- and di-)methyl ether, diethylene glycol (mono- and di-)ethyl ether, propylene glycol (mono- and di-)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono- and di-)methyl ether; and various organic solvents such as glycerol, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, and diethylene glycol monoisopropyl ether. These can be used alone or in combination of two or more.

[0044] Among these, it is more preferable to use ethyl acetate, propyl acetate, isopropanol, normal propanol, etc., and not use aromatic solvents such as toluene or ketone solvents such as methyl ethyl ketone, from the viewpoints of both work hygiene during printing and the harmfulness of packaging materials.

[0045] The coating agent for printing of the present invention may further contain, as necessary, colorants, extender pigments, leveling agents, antifoaming agents, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, and even antibacterial and antiviral agents, within limits that do not impair the effects of the present invention.

[0046] (Method of manufacturing a coating agent for printing) The coating agent for printing of the present invention can be produced by dissolving and / or dispersing the binder resin, plasticizer, chelating compound, etc. in an organic solvent. As a dispersing machine, a commonly used dispersing stirrer can be used.

[0047] The coating agent for printing of the present invention can be applied to substrates such as plastic materials, molded products, film substrates, and packaging materials by a common coating method, specifically, gravure roll coating (gravure coater), reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating, etc. Among these, from an industrial viewpoint, it is preferable to use gravure roll coating (gravure coater).

[0048] When the coating agent of the present invention is applied using a gravure coater, the viscosity thereof may be 12 to 30 seconds, more preferably 15 to 20 seconds, at 25° C. using a Zahn Cup #3 manufactured by Rigo Co., Ltd.

[0049] The thickness of the coating layer of the coating agent of the present invention can be adjusted appropriately depending on the application and the material of the substrate, but is preferably in the range of, for example, 0.5 to 2 μm.

[0050] (printed substrate) The printed substrate in the present invention can be obtained by printing a printing ink on a substrate made of a paper substrate, a plastic substrate, or the like to form a printed layer, and then coating the printed surface with the coating agent of the present invention to form a protective layer. Thus, the structure is substrate / printed layer / protective layer coated with coating agent.

[0051] Examples of printing inks include gravure ink, flexographic ink, offset ink, liquid toner, inkjet ink, etc., and examples of printing methods for these include gravure printing, flexographic printing, sheet-fed printing, digital printing, etc. Among these, many digital printing layers formed by digital printing are more brittle than printing layers formed by other methods such as gravure ink, flexographic ink, sheet-fed ink (offset ink), etc., and therefore the effect of the protective layer made of the printing coating agent of the present invention can be more effectively exhibited.

[0052] (digital printing layer) The ink used to form the digitally printed layer may be a liquid toner, aqueous inkjet ink, UV-curable inkjet ink, or solvent-based inkjet ink, and is not particularly limited as long as it is suitable for digital printing. Considering printing on plastic substrates, a liquid toner or UV-curable inkjet ink is preferred. For example, a liquid toner may be a typical toner in which toner particles are dispersed in water and / or an organic solvent. Liquid toners contain a binder resin for fixing the toner particles to the print medium, a colorant for visualizing the toner particles, a charge control agent for adjusting the electrical properties of the liquid toner, and the like.

[0053] As the binder resin, known resins commonly used in liquid toners can be used, and thermoplastic resins are particularly preferred. Examples of thermoplastic resins include polystyrene resins, styrene-acrylic acid copolymer resins, polyacrylic acid resins, polyethylene resins, ethylene-(meth)acrylic acid copolymer resins, polypropylene resins, polyester resins, polyurethane resins, and polyamide resins. These thermoplastic resins can be used alone or in combination of two or more.

[0054] Colorants can be materials that impart color to the liquid toner, such as pigments and dyes that impart color to the ink, such as black, magenta, cyan, yellow, and white, and can include colored pigments, magnetic particles, alumina, silica, and / or other ceramics or organometallics.

[0055] Examples of the charge control agent that can be used include known charge control agents such as metal salts of fatty acids such as naphthenic acid, oleic acid, octenoic acid, stearic acid, and lauric acid, metal salts of sulfosuccinic acid esters, nonionic surfactants such as polyoxyethylated alkylamines, fats and oils such as lecithin and linseed oil, polyvinylpyrrolidone, and organic acid esters of polyhydric alcohols.

[0056] (base material) The substrate used in the present invention is a paper substrate or a plastic substrate. Alternatively, these substrates may have a metal layer such as a metal foil or a metal vapor deposition layer, or an inorganic film such as an inorganic vapor deposition layer.

[0057] (Paper base material) The paper base material is produced using natural fibers for papermaking, such as wood pulp, on a known papermaking machine, but the papermaking conditions are not particularly specified. Examples of natural fibers for papermaking include wood pulps such as softwood pulp and hardwood pulp, non-wood pulps such as Manila hemp pulp, sisal hemp pulp, and flax pulp, and pulps obtained by chemically modifying these pulps. Pulp types that can be used include chemical pulps produced by sulfate cooking, acidic, neutral, or alkaline sulfite cooking, and soda cooking, as well as ground pulp, chemi-ground pulp, and thermomechanical pulp. Also, various commercially available high-quality papers, coated papers, lined papers, impregnated papers, cardboards, paperboards, etc. can be used.

[0058] (Plastic substrate) The plastic substrate may be any substrate used for plastic materials, molded articles, film substrates, packaging materials, etc. Specific examples include films and laminates made of polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene terephthalate (hereinafter sometimes referred to as PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; biodegradable resins such as polyhydroxycarboxylic acids such as polylactic acid, aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate); thermoplastic resins such as polyolefin resins such as polypropylene and polyethylene, polyimide resins, polyarylate resins, and mixtures thereof. Among these, films made of polyethylene terephthalate (PET), polyester, polyamide, polyethylene, and polypropylene are particularly preferred. These substrate films may be unstretched or stretched, and their manufacturing method is not limited. The thickness of the substrate film is also not particularly limited, but is typically within the range of 1 to 500 μm. The substrate film is preferably subjected to a corona discharge treatment, and may be vapor-deposited with aluminum, silica, alumina, or the like.

[0059] The substrate may also be a laminate (sometimes called a laminate film) having a laminate structure in which the above-mentioned paper substrates or film substrates are laminated by dry lamination, solventless lamination, or extrusion lamination, and the laminate may also include a metal foil, a metal vapor deposition film layer, an inorganic vapor deposition film layer, an oxygen absorbing layer, an anchor coat layer, a varnish layer, or the like.

[0060] The single-layer paper substrate or plastic substrate, or a laminate having a laminated structure thereof, is variously referred to, depending on the industry, method of use, etc., as functional film, flexible packaging film, shrink film, film for packaging daily necessities, film for packaging pharmaceuticals, film for packaging food, cartons, posters, flyers, CD jackets, direct mail, pamphlets, fine paper, coated paper, art paper, imitation paper, thin paper, cardboard, and various synthetic papers used for packaging cosmetics, beverages, pharmaceuticals, toys, equipment, etc., but the printing coating agent of the present invention can be used without any particular limitation. [Example]

[0061] The present invention will be described in more detail below using examples. Of course, the present invention should not be limited to the scope of these examples. Hereinafter, "parts" and "%" are by mass unless otherwise specified.

[0062] Example 1 (Method of manufacturing a coating agent for printing) Printing coating agent 1 was obtained by kneading a total of 100 parts of the following mixture: 6 parts of Laloflex (BASF), a vinyl chloride-vinyl isobutyl ether copolymer as a vinyl chloride copolymer resin; 19.8 parts of Acrylate (Taisei Fine Chemical Co., Ltd.), an acrylic resin; 1.5 parts of Topsizer (Kawaguchi Pharmaceutical Co., Ltd.), a plasticizer; 0.3 parts of Dispersion Wax (Gifu Ceramics Manufacturing Co., Ltd.), a polyethylene wax A; 0.2 parts of Ceridust (O.G. Corporation), a polyethylene wax B; 2 parts of Titanium Chelate Orgatix (Matsumoto Fine Chemical Co., Ltd.), a chelating compound; and ethyl acetate, normal propyl acetate, and methyl ketone in the proportions shown in Table 1.

[0063] (Examples 2 and 3) According to the formulations in Table 1, printing coating agents 2 and 3 of Examples 2 and 3 were obtained. In Example 3, instead of Laloflex (manufactured by BASF Ltd.), a copolymer of vinyl chloride and vinyl isobutyl ether used in Example 1, Solvine (manufactured by Nissin Chemical Industry Co., Ltd.), a copolymer of vinyl chloride and vinyl acetate, was used.

[0064] (Comparative Examples 1 and 2) According to the formulations in Table 1, printing coating agents H1 and H2 of Comparative Examples 1 and 2 were obtained. In Comparative Example 2, Paraloid (manufactured by Dowin Corporation) was used as the acrylic resin instead of Acrylit (manufactured by Taisei Fine Chemical Co., Ltd.), and normal propyl alcohol was also used.

[0065] (Printing methods for various printing coating agents) A printing coating agent diluted to 17 seconds in a Zahn cup #3 (dilution solvent: ethyl acetate / normal propyl alcohol = 1 / 1 by mass ratio) was printed onto a digitally printed material (using a Hewlett-Packard Indigo 2000) printed on a 20 μm thick stretched polypropylene film (OPP FOR manufactured by Futamura Chemical Co., Ltd., 20 μm thick) using a Helio 175L solid plate to obtain a printed substrate. The printing coating surface of the printable substrate was evaluated using the following evaluation methods.

[0066] (Evaluation method) [Base material adhesion] The coating film surface for printing obtained by the above printing method was left for 24 hours, and then cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the coating film surface, and the tape was quickly peeled off, and the condition of the coating film surface was visually evaluated. A rating of 4 or higher is within the practical range. (Evaluation criteria) 5: The coating surface does not peel off from the film at all. 4: Less than 20% of the coating surface area peels off from the film. 3: 20% or more but less than 50% of the coating surface area peels off from the film. 2: The area ratio of the coating surface is 50% or more but less than 80%. 1: More than 80% of the coating surface area peels off from the film.

[0067] [Alcohol resistance 1] (Mold killer antibacterial spray) The coating surface for printing obtained by the above printing method was rubbed 30 times under a load of 200 g with a cloth (metal cloth) soaked in a disinfectant spray using a Gakushin-type abrasion resistance tester, and the alcohol suitability was evaluated from the changes in the coating surface. A rating of 4 or above is within the practical range. (Evaluation criteria) 5: No change on the coating surface or the patch cloth. 4: There is no change in the coating surface, but the patch cloth becomes discolored. 3: Streaky scratches are observed on the coating surface. 2: Thick, streaky scratches are observed on the coating surface. 1: Surface scratches are observed on the coating surface.

[0068] [Alcohol resistance 2] (75% ethanol) The printing coating film surface obtained using the above printing method is rubbed 30 times with a cotton swab soaked in 75% alcohol, and the ink removal is evaluated. The same test is performed five times. A rating of 4 or above is within the practical range. (Evaluation criteria) 5: No change on the coating surface or cotton swab. 4: There is no change in the coating surface, but the cotton swab becomes discolored. 3: Slight ink removal is observed on the coating surface. 2: Thick streaks of ink removal are observed on the coating surface. 1: Most of the ink on the coating surface is removed.

[0069] [PVC blocking resistance] The coating film surface for printing obtained by the printing method was overlapped with a commercially available soft vinyl chloride sheet (antibacterial clear, checkered pattern, reversible pattern (front and back)) cut to the same size as the coating film surface, and the coating film surface was then coated with a pressure of 0.5 kg / cm 2After applying a load of 1000kJ / s and leaving it in an atmosphere of 50°C and 80% humidity for 24 hours, the coating surface and the polyvinyl chloride sheet were peeled off, and the PVC blocking resistance was evaluated based on the degree of peeling of the coating agent. (Evaluation criteria) 5: The coating did not peel off at all. 4: The area where the coating has peeled off from the film is 20% or more but less than 50%. 3: The area where the coating has peeled off from the film is 50% or more but less than 75%. 2: The area where the coating has peeled off from the film is 75% or more but less than 90%. 1: The area where the coating has peeled off from the film is 90% or more.

[0070] [Table 1]

Claims

1. A printing coating agent containing a vinyl chloride-vinyl isobutyl ether copolymer and an acrylic resin as the main binder resin, and an organic solvent, characterized in that the printing coating agent satisfies the following: (1) The coating agent contains a plasticizer in an amount of 1.0 to 10.0% by mass based on the total solid content of the coating agent. (2) The coating agent contains a chelate compound in an amount of 0.03 to 10.0% by mass based on the total solid content of the coating agent. (3) The coating agent contains 0.15 to 10.0 mass % of hydrocarbon wax based on the total solid content of the coating agent.

2. 2. The coating agent for printing according to claim 1, wherein the chelate compound is a titanium-based chelate compound.

3. 3. The coating agent for printing according to claim 1, wherein the plasticizer is a sulfonic acid amide plasticizer.

4. The coating agent for printing according to any one of claims 1 to 3, which is for digital printing.

5. A printed substrate obtained by coating a printed substrate with the coating agent for printing according to any one of claims 1 to 4.

6. A printed substrate obtained by coating a digitally printed substrate with the coating agent for printing according to any one of claims 1 to 4.

7. A container or packaging material using the printed substrate according to claim 5 or 6.

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