JP7494787B2 - Overcoat and print materials - Google Patents

Description

The present invention relates to an overcoat agent and a printed matter using the same.

In flexible packaging and other packaging that uses film substrates such as polyester film, nylon film, and polyolefin film, printing ink is printed to add design, beauty, or product information. Printing on film substrates can be broadly divided into front printing, where printing is done directly on the surface of the film, and back printing, where ink is printed on the back side of the film. When packaging is done with front printing, the printed layer is placed on the outermost side and can be directly observed with the naked eye. On the other hand, when packaging is done with back printing, the outermost side is the film substrate, and the printed layer is sandwiched between the substrate and a thermoplastic substrate called a sealant (called a laminate). Therefore, unlike front printing, packaging with back printing has the difference that the printed layer can be seen through the film substrate.

Surface-printed printed compositions form a printing ink layer on the outermost surface, and therefore often have inferior glossiness, scratch resistance, and heat resistance compared to the above-mentioned film substrate (Patent Document 1). On the other hand, reverse-printed printed compositions (laminate laminates) have the characteristic that high glossiness and scratch resistance can be easily obtained compared to surface-printed printed compositions in which the outermost layer of the package is a printing layer, since the physical properties of the film substrate itself are effectively utilized in the outermost layer of the package. However, this method requires printing ink onto the substrate and then attaching another film onto the printing layer, which is a time-consuming process, and in addition, physical properties such as adhesion between the film substrate and the printing layer and delamination (floating) are often insufficient due to the process, and there are also cost issues due to the need for adhesives and lamination processes.

Therefore, in order to impart high gloss and heat resistance to surface-printed structures or packages, a method of forming a protective layer on the surface of the surface-printed layer using an overcoat agent has been investigated. This method is expected to impart gloss and scratch resistance to the same degree as laminates without the need for complicated manufacturing processes as with laminates.
However, as conventional overcoating agents, a urethane resin-based coating agent (Patent Document 2), an acrylic resin-based coating agent (Patent Document 3), an amide resin-based coating agent (Patent Document 4), a polylactic acid-based overcoating agent (Patent Document 5), and the like have been proposed, but all of them have room for improvement in terms of gloss, heat resistance, and even odor, compared to laminated bodies.

JP 2019-119824 A JP 2018-145283 A Patent No. 5828196 JP 2016-079306 A JP 2003-147265 A

The present invention aims to provide an overcoat agent that can achieve high gloss equivalent to or greater than that of the film surface of a laminate, in addition to various physical properties such as adhesion, heat resistance, and odor, even in surface-printed compositions.

As a result of extensive research into the problem, the inventors discovered that the problem could be solved by using the overcoat agent described below, which led to the creation of the present invention.

That is, the present invention provides an overcoat agent for forming a transparent protective layer disposed on a print layer, the overcoat agent containing a binder resin and an isocyanate curing agent,
The overcoat agent relates to the binder resin, which comprises a vinyl chloride copolymer resin and a polyester resin having a ring structure, and the vinyl chloride copolymer resin is contained in an amount of 30 mass % or more based on the total mass of the binder resin.

The present invention also relates to the above-mentioned overcoat agent, in which the polyester resin having a ring structure includes a polyester resin having an aromatic ring structure.

The present invention also relates to the above overcoat agent, in which the ring structure content in the total solid content of the overcoat agent is 0.5 to 10% by mass or less.

The present invention also relates to the above overcoat agent, in which the mass ratio of the vinyl chloride copolymer resin to the polyester resin having a ring structure is 80:20 to 40:60.

The present invention also relates to the above-mentioned overcoat agent, in which the polyester resin having a ring structure includes a vegetable oil-modified alkyd resin having a ring structure.

The present invention also relates to the above overcoat agent, in which the isocyanate curing agent has a ring structure.

The present invention also relates to a printed matter having, in order, a substrate, a printed layer, and a transparent protective layer formed from the above-mentioned overcoat agent.

The present invention makes it possible to provide an overcoat agent that can exhibit high gloss equal to or greater than that of the film surface of a laminate, in addition to various physical properties such as adhesion, heat resistance, and odor.
In addition, it is now possible to produce printed matter with performance equal to or better than that of laminated laminates, even in surface printing configurations, which was previously difficult, and this can contribute to simplifying lamination and other manufacturing processes, reducing costs, and reducing _CO2 emissions by reducing the amount of plastic base material used.

The following describes in detail an embodiment of the present invention. However, the following description of the embodiment or requirements is merely an example of how the present invention can be implemented, and the present invention is not limited to these details as long as it does not exceed the gist of the invention.

The present invention provides an overcoat agent for forming a transparent protective layer disposed on a print layer, the overcoat agent containing a binder resin and an isocyanate curing agent,
The binder resin is an overcoat agent containing a vinyl chloride copolymer resin and a polyester resin having a ring structure, and the vinyl chloride copolymer resin is contained in an amount of 60 mass% or more in the total mass of the binder resin. By containing a vinyl chloride copolymer resin and a polyester resin having a ring structure in the binder resin and containing the vinyl chloride copolymer resin in an amount of 60 mass% or more in the total mass of the binder resin, it is possible to improve high gloss, adhesion, heat resistance, odor, etc.
The transparent protective layer preferably has a surface gloss value (60°) of 80 to 135.
The overcoat agent includes a binder resin containing a polyester resin and an isocyanate curing agent. The polyester resin in the overcoat agent imparts flexibility and adhesion, and the isocyanate curing agent imparts heat resistance and scratch resistance. In order to improve the gloss value and adhesion, it is necessary for the polyester resin to have a ring structure, and the ring structure is preferably an aromatic ring structure.

The gloss value is the value measured according to JIS Z8741, and is the measured value at an incidence angle of 60°. The gloss value can be measured, for example, using a Micro-TRI-glossmeter manufactured by BYK-Gardner, under measurement conditions of an incidence angle of 60° and a receiving angle of 60°.

The overcoat agent of the present invention is preferably used for surface printing. In this specification, surface printing refers to the case where, when printing on a paper or plastic substrate, the printing ink and the overcoat agent are printed on the substrate in that order, and the printed pattern can be confirmed from the printed surface. The transparent protective layer made of the overcoat agent becomes the outermost layer in the printed matter of the present invention. Each material constituting the overcoat agent of the present invention will be described below.

<Binder resin>
The binder resin refers to the resin components contained in the overcoat agent other than the curing agent, additives, and solvent, and the vinyl chloride copolymer resin is contained in the total amount of the binder resin in an amount of 30% by mass or more, preferably 40% by mass or more, and more preferably 60% by mass or more, and the upper limit is preferably 95% by mass or less, 90% by mass or less, or 80% by mass or less.
The polyester resin having a ring structure is preferably contained in an amount of 70% by mass or less, more preferably 60% by mass or less and 50% by mass or less.

<Polyester Resin Having a Ring Structure>
Examples of polyester resins having a ring structure include polyester resins obtained by reacting a polyhydric alcohol with a carboxylic acid using a known esterification polymerization reaction, and alkyd resins described below, and preferred examples of such polyester resins include those in which the polyhydric alcohol and/or the carboxylic acid have a ring structure.
The polyester resin having a ring structure is not particularly limited as long as it contains 50% by mass or more of polyester structure in the total mass, and is appropriately produced by a known method. The content of the ring structure in the polyester resin is preferably 1 to 80% by mass, more preferably 5 to 30% by mass. The content of the ring structure is preferably 0.5 to 10% by mass of the total mass of solid content in the overcoat agent. The solid content refers to the total mass of non-volatile components of the overcoat agent.
Suitable examples of the ring structure include an aromatic ring structure, an alicyclic ring structure, and a heterocyclic structure (such as a pyranose ring structure), and among these, it is preferable that the ring structure contains an aromatic ring structure.

The weight average molecular weight of the polyester resin is preferably 500 to 200,000, and more preferably 2,000 to 150,000. This is because it provides good adhesion and blocking resistance, as well as work efficiency and printability in the ink printing process.

Examples of alicyclic alcohols among polyhydric alcohols include 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, isosorbide, etc. Monofunctional alcohols such as cyclohexanol, cyclohexaneethanol, 4-tert-butylcyclohexanol, menthol, 2-ethyl-4-(2,2,3-trimethyl-3-cyclopentenyl)-2-buten-1-ol, 4-isopropylcyclohexanol, and 2-(tert-butyl)cyclohexanol can also be used in combination.
The polyhydric alcohols can be used alone or in combination of two or more kinds.

Among the polyhydric alcohols, aromatic alcohols include 1,4-benzenedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,2-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, hydroquinone, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, etc., which can be used alone or in combination of two or more.

Among the dibasic acids, alicyclic dibasic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,1-cyclopentanediacetic acid, and decahydro-1,4-naphthalenedicarboxylic acid.

Among the dibasic acids, aromatic dibasic acids include phthalic acid, isophthalic acid, terephthalic acid, 1,2-phenylene diacetic acid, 1,3-phenylene diacetic acid, 1,4-phenylene diacetic acid, 4-(carboxymethyl)benzoic acid, etc., which can be used alone or in combination of two or more.

In addition, the above polyester resins can also use polyhydric alcohols that do not have a ring structure and dibasic acids that do not have a ring structure.

Examples of polyhydric alcohols that do not have an alicyclic structure include, but are not limited to, 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, and pentaerythritol.

Examples of dibasic acids that do not have a ring structure include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and phthalic acid. If necessary, monobasic acids such as formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, and linoleic acid may be used in combination.

Furthermore, acid anhydrides may be used, such as succinic anhydride, methyl succinic anhydride, 2,2-dimethyl succinic anhydride, butyl succinic anhydride, isobutyl succinic anhydride, hexyl succinic anhydride, octyl succinic anhydride, dodecenyl succinic anhydride, phenyl succinic anhydride, glutaric anhydride, 3-allyl glutaric anhydride, 2,4-dimethyl glutaric anhydride, 2,4-diethyl glutaric anhydride, butyl glutaric anhydride, and hexyl glutaric anhydride. maleic anhydride, 2-methylmaleic anhydride, 2,3-dimethylmaleic anhydride, butyl maleic anhydride, pentyl maleic anhydride, hexyl maleic anhydride, octyl maleic anhydride, decyl maleic anhydride, dodecyl maleic anhydride, 2,3-dichloromaleic anhydride, phenyl maleic anhydride, 2,3-diphenyl maleic anhydride, itaconic anhydride, citraconic anhydride, phthalic anhydride, 4-methylphthalic anhydride, daclinic anhydride, phthalic ... Examples of the anhydrides include mer acid, 1,2,3,6-tetrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, methylbutenyl-1,2,3,6-tetrahydrophthalic anhydride, chlorendic anhydride, head acid anhydride, biphenyl dicarboxylic anhydride, himic anhydride, endomethylene-1,2,3,6-tetrahydrophthalic anhydride, methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride, methylcyclohexene dicarboxylic anhydride, trimellitic anhydride, 1,8-naphthalenedicarboxylic anhydride, and octahydro-1,3-dioxo-4,5-isobenzofuran dicarboxylic anhydride.

(Alkyd resin)
Alkyd resins are one type of polyester resins having the above ring structure, and examples thereof include alkyd resins synthesized by polycondensation of a carboxylic acid compound, a fatty acid (including animal and vegetable oils) and an alcohol compound, and alkyd resins obtained by reacting the above fatty acid or its fatty acid monoester with a carboxylic acid compound, followed by an esterification reaction of the alcohol compound. All of these correspond to alkyd resins modified with fats and oils (fat-modified alkyd resins).
The hydroxyl value of the alkyd resin used in the present invention is preferably 5 to 200 mgKOH/g, more preferably 20 to 150 mgKOH/g. The weight average molecular weight of the alkyd resin is preferably 500 to 200,000, more preferably 2,000 to 150,000. The content of the ring structure in the total amount of the alkyd resin is preferably 1 to 80 mass%, more preferably 5 to 30 mass%.

The carboxylic acid compound used in the synthesis of the alkyd resin is preferably a polybasic acid such as a dibasic acid, and suitable examples of the dibasic acid include the aromatic carboxylic acids (including anhydrides) and alicyclic carboxylic acids (including anhydrides). Among these, aromatic carboxylic acids (including anhydrides) are preferred, and suitable examples of such compounds include phthalic anhydride, phthalic acid, isophthalic acid, and terephthalic acid.

The alcohol compounds used in the synthesis of the alkyd resin preferably include alicyclic alcohols, aromatic alcohols, and alcohols having no ring structure, and the same as those mentioned above can be preferably used. Among them, it is preferable to use alcohols having no ring structure, and as dihydric alcohol compounds, preferably ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, cyclohexanedimethanol, nepentyl glycol, etc. can be mentioned.
Examples of trihydric or higher alcohol compounds include aliphatic polyhydric alcohols such as (mono-, di-, or tri)glycerin, (mono-, di-, or tri)trimethylolethane, (mono-, di-, or tri)trimethylolpropane, (mono-, di-, or tri)trimethylolalkane, (mono-, di-, or tri)pentaerythritol, and sorbitol.

The fatty acid may be a mixed fatty acid, and preferred examples of the fatty acid include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, palmitic acid, and stearic acid.

Examples of the above-mentioned animal and vegetable oils include hemp seed oil, linseed oil, perilla oil, oiticica oil, olive oil, cacao oil, kapok oil, torreya oil, mustard oil, apricot kernel oil, tung oil, kukui oil, walnut oil, poppy seed oil, sesame oil, safflower oil, radish seed oil, soybean oil, safflower oil, camellia oil, corn oil, rapeseed oil, niger oil, rice bran oil, palm oil, castor oil, sunflower oil, grape seed oil, almond oil, pine seed oil, cottonseed oil, coconut oil, peanut oil, and dehydrated castor oil.

The fatty acid monoester may be an alkyl ester formed from the fatty acid and an alcohol, and preferred examples of the alcohol include alkanols such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol.

(Ring Structure Content in Total Solid Mass of Overcoat Agent)
The content of the ring structure in the total mass of the solid content of the overcoat agent can be calculated by the following formula.
Ring structure content (%)=total atomic weight of all atoms constituting the ring structure in one molecule of raw material/molecular weight of raw material Here, the raw material refers to compounds constituting an overcoat agent such as a binder resin or an isocyanate-based curing agent, and all atoms constituting the ring structure in one molecule of raw material means atoms (carbon atoms or heteroatoms) constituting the ring structure itself, such as an aromatic ring, and hydrogen atoms directly bonded to atoms constituting the ring structure itself, and is defined as not including atoms of substituents such as methyl groups and nitro groups.
For example, in the case of a trimethylolpropane adduct compound of xylylene diisocyanate (XDI-TMP adduct), which is a raw material for an isocyanate curing agent, there are three ring structures (C ₆ H ₄ ) which are aromatic groups while the total molecular weight is 698.7, and the total molecular weight (C ₁₈ H ₁₂ ) is 228.3, so the ring structure content is 228.3/698.7=33%.
When the ring structure content is calculated based on the binder resin, it is the ring structure content in the binder resin, and when calculated based on the solid content, it is the ring structure content in the solid content.

<Vinyl chloride copolymer resin>
The vinyl chloride copolymer resin is not particularly limited as long as it contains a structural unit derived from vinyl chloride and a structural unit derived from another monomer, and among these, vinyl chloride-vinyl acetate copolymer resin and vinyl chloride-acrylic copolymer resin are preferred.

<Vinyl chloride-vinyl acetate copolymer resin>
The vinyl chloride-vinyl acetate copolymer resin is a copolymer of vinyl chloride and vinyl acetate, and the molecular weight is preferably 5,000 to 100,000, more preferably 20,000 to 70,000 in weight average molecular weight. The vinyl acetate monomer-derived structure is preferably 1 to 30 mass% and the vinyl chloride monomer-derived structure is preferably 70 to 95 mass% in 100 mass% of the solid content of the vinyl chloride-vinyl acetate copolymer resin. In this case, the solubility in organic solvents is improved, and further, the adhesion to the substrate, the coating properties, the laminate strength, etc. are improved.
In order to improve the solubility in organic solvents, it is more preferable that the polyvinyl alcohol contains a hydroxyl group derived from a saponification reaction or copolymerization, and the hydroxyl value is preferably 20 to 200 mgKOH/g. The glass transition temperature is preferably 50°C to 90°C.

<Vinyl chloride-acrylic copolymer resin>
The vinyl chloride-acrylic copolymer resin is mainly composed of a copolymer resin of vinyl chloride monomer and acrylic monomer, and the acrylic monomer preferably contains a (meth)acrylic acid hydroxyalkyl ester in order to improve the adhesiveness to the substrate and the solubility in organic solvents. The acrylic monomer may be incorporated in the main chain of polyvinyl chloride in a block or random manner, or may be graft-polymerized to the side chain of polyvinyl chloride. The vinyl chloride-acrylic copolymer resin preferably has a weight average molecular weight of 10,000 to 100,000, more preferably 30,000 to 70,000. In addition, the hydroxyl value is preferably 20 to 200 mgKOH/g, and the glass transition temperature is preferably 50°C to 90°C.

The vinyl chloride monomer-derived structure in the vinyl chloride-acrylic copolymer resin is preferably 70 to 95% by mass out of 100% by mass of the vinyl chloride-acrylic copolymer resin solids. In this case, the solubility in organic solvents is improved, and the adhesion to the substrate, coating properties, laminate strength, etc. are also improved.

In the following description, (meth)acrylic and (meth)acrylate refer to methacrylic and acrylic, methacrylate and acrylate, respectively.

The acrylic monomer is preferably one having a hydroxyl group, and examples thereof include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate, as well as glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate, caprolactone-modified (meth)acrylate, and hydroxyethylacrylamide. Among these, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl acrylate are more preferred because they improve solubility in solvents. These can be used alone or in combination of two or more. Acrylic monomers other than those mentioned above may be included at any time.

In one embodiment, the binder resin preferably contains the vinyl chloride copolymer resin and the polyester resin in a certain ratio range. In this case, the ratio of the vinyl chloride copolymer resin to the polyester resin is preferably 40:60 to 80:20 by mass, and more preferably 50:50 to 70:30 by mass. The polyester resin preferably contains an alkyd resin. The binder resin preferably contains 70% by mass or more of the polyester resin and the vinyl chloride copolymer resin in total, and more preferably 80% by mass or more.

<Concomitant Resin>
In the embodiment of the present invention, the binder resin is also suitable when other resins are used in combination with the polyester resins and vinyl chloride copolymer resins, and examples thereof include, but are not limited to, polyurethane resins, polyamide resins, rosin resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, styrene resins, dammar resins, styrene-maleic acid copolymer resins, styrene-acrylic copolymer resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyacetal resins, petroleum resins, and modified resins thereof. These resins can be used alone or in combination of two or more.

<Isocyanate hardener>
In the overcoat agent of the present invention, an isocyanate curing agent is used to improve heat resistance. In order to improve gloss, the isocyanate curing agent preferably has a ring structure. Suitable examples of the ring structure include the same structures as those in the polyester resin. Among them, an alicyclic ring structure and/or an aromatic ring structure are more preferred.
As a specific embodiment of the isocyanate curing agent, polyisocyanate compounds and modified isocyanate compounds can be suitably used. Specifically, the modified isocyanate compounds are dimeric allophanate type isocyanate compounds, trimer biuret type isocyanate compounds, adduct type isocyanate compounds, and isocyanurate type isocyanate compounds. The biuret type isocyanate compounds are isocyanate compounds having a structure in which urea is dimerized. Also, the isocyanurate type isocyanate compounds are isocyanate compounds that are cyclic trimers of polyisocyanate compounds. The adduct type isocyanate compounds refer to adducts of polyisocyanate compounds and polyhydric alcohols, and examples thereof include reaction products with xylylene diisocyanate.
As the polyisocyanate compound, diisocyanates are preferred, and aromatic diisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, etc., alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate, etc., and aromatic aliphatic diisocyanates such as α,α,α',α'-tetramethylxylylene diisocyanate, etc. are suitable.
Specific examples of commercially available modified isocyanate compounds include Duranate 24A-100, 22A-75P, TPA-100, TKA-100, and P301-75E (manufactured by Asahi Kasei Corporation), Takenate D-160N, D-170N, D-110N, and D-101 (manufactured by Mitsui Chemicals), and Desmodur N3200, N3600, Z4470BA, and L75(C) (manufactured by Covestro).
The ring structure content in the isocyanate curing agent is preferably 5 to 50% by mass, more preferably 20 to 40% by mass. The ring structure preferably has an alicyclic group and/or an aromatic group. The isocyanate curing agent preferably has an isocyanate group (NCO) content as specified in JIS K6806 of 3 to 30% (mass %), more preferably 5 to 25%.

The isocyanate hardener is preferably mixed in an amount of 0.25 to 8 equivalents per equivalent of crosslinkable functional group (such as a hydroxyl group or amino group) of the binder resin, and more preferably 0.8 to 3 equivalents. The ratio of binder resin to isocyanate hardener used is preferably 95:5 to 10:90 by mass, and even more preferably 90:10 to 20:80 by mass. Within this range, sufficient crosslink density is obtained, and heat resistance is good.

<Additives>
The overcoat agent of the present invention may appropriately contain conventionally known additives. In producing the overcoat agent, additives such as a wetting agent, an adhesion aid, a leveling agent, an antifoaming agent, an antistatic agent, a viscosity modifier, a chelating crosslinking agent, a trapping agent, an antiblocking agent, wax components other than those mentioned above, and a silane coupling agent may be used as necessary.

<Organic Solvent>
The overcoat agent of the present invention preferably contains an organic solvent as a liquid medium (organic solvent-based overcoat agent). Although not limited to the following, the organic solvent used may be a known organic solvent such as an aromatic organic solvent such as toluene or xylene, a ketone-based organic solvent such as methyl ethyl ketone or methyl isobutyl ketone, ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, an ester-based organic solvent, an alcohol-based organic solvent such as methanol, ethanol, n-propanol, isopropanol, or n-butanol, or a glycol ether-based solvent such as ethylene glycol monopropyl ether or propylene glycol monomethyl ether, or may be used in combination. Among them, an organic solvent that does not contain an aromatic organic solvent such as toluene or xylene (non-toluene-based organic solvent) is more preferable. More preferably, an organic solvent consisting of an ester-based organic solvent or an alcohol-based organic solvent is preferable. In this case, the glycol ether-based organic solvent may be contained in an amount of 6% by mass or less in 100% by mass of the overcoat agent. The overcoat agent of the present invention may contain water as a liquid medium, but the content of water is preferably 0.1 to 5% by mass in 100% by mass of the liquid medium. However, it is not limited to these.

(Production of Overcoat Agent)
The overcoat agent is not particularly limited in the production method, and may be produced by adding a binder resin solution in which a binder resin and an organic solvent are dissolved or dispersed, and a solvent to an agitator equipped with an agitating blade, a rotating blade, etc., and mixing and agitating the binder resin solution and the organic solvent. The agitation speed is not particularly limited, and may be 50 to 300 rpm. In order to improve the handling and application properties of the overcoat agent, a solvent may be appropriately added. The isocyanate curing agent may be added at the beginning, but depending on the storage conditions and the type of isocyanate curing agent, it is preferable to mix the overcoat agent immediately before use. The viscosity of the overcoat agent is preferably 20 to 200 mPa·s, since the overcoat agent is used by a printing method, etc.

(Overcoat application and printing)
The overcoat agent of the present invention can be applied by a known printing method. For example, gravure printing, flexographic printing, microgravure printing, etc. can be mentioned, and gravure printing is preferred. In the gravure printing method, the overcoat agent enters the recesses that become the image areas engraved on the surface of a cylindrical cylinder, and after the overcoat agent of the non-image areas is scraped off with a metal plate called a doctor, the overcoat agent remaining in the recesses of the cylinder is transferred onto the printing film to form a coating layer. The amount of overcoat agent applied can be controlled by the depth of the recesses. The coating on the printing film can be applied multiple times, taking into consideration the film properties such as drying after coating, gloss of the coating film, scratch resistance, and high-temperature hot water resistance. The amount of coating and the number of coatings can be appropriately selected as the form of use of the overcoat agent. The thickness of the transparent protective layer formed by the overcoat agent of the present invention is preferably 0.5 to 10 μm, more preferably 1 to 6 μm.

The applied overcoat agent is preferably dried at a temperature between 40 and 80°C, resulting in a printed matter with a tough, transparent protective layer.

The overcoat agent of the present invention is applied onto the printing layer formed by the printing ink to form a printed matter. The printing ink is preferably a printing ink consisting of a binder resin, a pigment, a solvent, and, if necessary, additives. Although not limited to the following, it is preferable that the printing ink contains, as the binder resin constituting the printing ink, a urethane resin, a polyamide resin, an acrylic resin, a vinyl chloride-vinyl acetate copolymer resin, a nitrocellulose resin, a chlorinated polypropylene resin, an ethylene-vinyl acetate copolymer resin, a vinyl acetate resin, a polyester resin, an alkyd resin, a rosin-based resin, a rosin-modified maleic acid resin, a ketone resin, a cyclized rubber, a chlorinated rubber, a butyral, a petroleum resin, or the like. Among them, it is more preferable that the printing ink contains at least one selected from the group consisting of a urethane resin, a polyamide resin, an acrylic resin, a vinyl chloride-vinyl acetate copolymer resin, and a nitrocellulose resin. In particular, a printing ink containing a urethane resin is even more preferable because it has good adhesion to a film substrate.

The urethane resin can be obtained by known methods, such as those disclosed in JP-A-62-153366, JP-A-62-153367, JP-A-1-236289, JP-A-2-64173, JP-A-2-64174, and JP-A-2-64175. Specifically, the urethane resin is produced by a two-stage method in which a polyol and a diisocyanate compound are reacted in a ratio that results in an excess of isocyanate groups to obtain a prepolymer having terminal isocyanate groups, and the obtained prepolymer is reacted with a chain extender and/or a reaction terminator in a suitable solvent, or a one-stage method in which a polyol, a diisocyanate compound, a chain extender, and/or a reaction terminator are reacted at once in a solvent. Of these methods, the two-stage method is preferred to obtain a uniform urethane resin.

The printing ink may contain additives, such as pigment dispersants, leveling agents, defoamers, leveling agents, waxes, trapping agents, plasticizers, infrared absorbers, ultraviolet absorbers, anti-blocking agents, antistatic agents, and flame retardants.

As the pigment, any of the C.I. pigments described in the Color Index that can be generally used in printing inks and paints can be used. Examples include colored pigments such as titanium oxide, red iron oxide, Prussian blue, ultramarine blue, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Furthermore, examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo chelate pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. The content of these pigments in the printing ink can be 0.5 to 50% by weight.

Solvents used in printing inks include water, radiation-curable monomers, and the same solvents as those used in the overcoat agent described above. Known alcohol-based organic solvents, ketone-based organic solvents, ester-based organic solvents, aliphatic hydrocarbon-based organic solvents, and alicyclic hydrocarbon-based organic solvents can be used. Taking into consideration the solubility of the urethane resin and other resins, drying properties during printing, and the like, it is preferable to use them in combination.

Printing ink can be produced by a known method of dispersing a pigment using a resin, a solvent, etc. For example, a pigment dispersion is produced by dispersing a pigment in a solvent using a urethane resin, a co-resin, a dispersant, etc., and resins, additives, etc. are added to the resulting pigment dispersion as necessary.

(Base material)
The substrate used in the present invention may suitably be a plastic substrate on a film, a paper substrate, etc. Among them, the use of a plastic substrate is preferred, and since a process such as heat sealing is required, a plastic substrate having thermoplastic properties is preferred.
Examples of plastic substrates include polyethylene, polypropylene and other polyolefin substrates, polyethylene terephthalate, polylactic acid and other polyester substrates, polystyrene substrates, polystyrene-based resins such as AS resin and ABS resin, polycarbonate substrates, polyamide substrates, polyvinyl chloride substrates, various substrates such as polyvinylidene chloride, cellophane substrates, paper substrates, aluminum foil substrates, etc., or film- or sheet-shaped substrates made of composite materials of these. Among these, polyester substrates and polyamide substrates having high glass transition temperatures are preferably used.

The above-mentioned substrate may have a surface that has been subjected to deposition coating treatment with metal oxide or the like and/or coating treatment with polyvinyl alcohol or the like, for example, GL-AE manufactured by Toppan Printing Co., Ltd., in which aluminum oxide is deposited on the substrate surface, or IB-PET-PXB manufactured by Dai Nippon Printing Co., Ltd., may be mentioned. Furthermore, if necessary, a substrate treated with additives such as an antistatic agent or an ultraviolet ray inhibitor, or a substrate surface that has been subjected to corona treatment or low-temperature plasma treatment may also be used.

The above-mentioned plastic substrates include (1) plastic substrates made of a single type, and (2) multi-layered plastic substrates made of multiple types of plastic substrates. In the present invention, a multi-layered plastic substrate is preferable from the viewpoints of toughness, moisture resistance, etc. Furthermore, in the present invention, the multi-layered plastic substrate is preferably a multi-layered plastic substrate having heat sealability (thermoplasticity) on the side opposite to the printed side. When a multi-layered plastic substrate is used, it is possible to easily make a bag without post-processing after applying an overcoat agent, which has the advantage of simplifying the packaging manufacturing process.

Examples of multilayer plastic substrates include two-layer structures such as PET/CPP, OPP/CPP, and Ny/CPP; three-layer structures such as PET/aluminum/CPP, PET/Ny/CPP, Ny/PET/CPP, and Ny/vapor-deposited PET/CPP; and four-layer structures such as PET/aluminum/Ny/CPP, which are laminated via an anchor coating agent and adhesive. Even with such multilayer plastic substrates, it is preferable to subject the printing surface to corona treatment, frame treatment, plasma treatment, etc., as this improves the adhesion of the printing ink layer.

Lamination of plastic substrates can be performed by known methods, such as the extrusion lamination method, which uses an anchor coating agent such as an imine-based, polybutadiene-based, or titanium-based agent and laminates molten polyethylene resin, or the dry lamination method, which applies an adhesive such as a urethane-based adhesive and laminates the substrate. Multilayer plastic substrates obtained by the dry lamination method are particularly preferred for applications that require resistance to high-temperature hot water.

The printed matter of the present invention is formed by printing a printing ink layer and an overcoat agent in that order on a plastic substrate. As mentioned above, it is preferable to use a heat-sealable multilayer film as the plastic substrate in terms of ease of post-processing.

The packaging material obtained in this way can be widely used as a packaging material for foods, medicines, etc. In addition, because the front-printed structure exhibits excellent resistance to high-temperature hot water, it can also be used in applications where high resistance is required with the conventional reverse-printed structure.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Note that parts and % in the present invention represent parts by mass and % by mass unless otherwise noted.

<Synthesis of polyurethane resin for printing ink>
[Synthesis Example 1] (Preparation of urethane resin PU1 solution)
150 parts of polyester polyol (PMPA) having a number average molecular weight of 1,000 obtained by the reaction of adipic acid and 3-methyl-1,5-pentanediol, 50 parts of polypropylene glycol (PPG700) having a number average molecular weight of 700, 103.4 parts of isophorone diisocyanate (IPDI), and 75.8 parts of ethyl acetate (ethyl acetate) were reacted under a nitrogen gas flow at 80 ° C. for 4 hours to obtain a resin solution of a terminal isocyanate urethane prepolymer. Next, the resin solution of the terminal isocyanate urethane prepolymer was gradually added at 40 ° C. to a mixture of 44.6 parts of isophorone diamine (IPDA) and 736.2 parts of a mixed solvent of ethyl acetate / isopropanol (IPA) = 50 / 50 (mass ratio) to obtain a polyurethane resin solution PU1.

<Synthesis of polyester resin A for overcoat agent>
[Synthesis Example 2] (Preparation of Polyester Resin A Solution)
190.1 parts of phthalic anhydride, 207.9 parts of castor oil, 38.6 parts of ethylene glycol, 63.4 parts of pentaerythritol, and 500.0 parts of ethyl acetate were charged into a reactor, and gradually heated to 160-240°C while stirring under a nitrogen stream to carry out an esterification reaction. The reaction was carried out at 195°C for 1 hour or more, and when the acid value became 15 or less, the pressure in the reactor was gradually reduced to 1-2 Torr. When a predetermined viscosity was reached, the reaction was stopped and the resin was taken out, to obtain a polyester resin A. The polyester resin A has an aromatic ring structure in an amount of 6% by mass.

<Synthesis of polyester resin B for overcoat agent>
[Synthesis Example 3] (Preparation of Polyester Resin B Solution)
156.3 parts of terephthalic acid, 156.3 parts of isophthalic acid, 70.0 parts of ethylene glycol, 117.4 parts of neopentyl glycol, and 500.0 parts of ethyl acetate were charged into a reactor, and gradually heated to 160-240°C while stirring under a nitrogen stream to carry out an esterification reaction. The reaction was carried out at 240°C for 1 hour or more, and when the acid value became 15 or less, the pressure in the reactor was gradually reduced to 1-2 Torr. When a predetermined viscosity was reached, the reaction was stopped and the mixture was taken out, to obtain a polyester resin B. The polyester resin B has an aromatic ring structure of 11% by mass.

[Synthesis Example 4] (Preparation of Polyester Resin C Solution)
143.1 parts of terephthalic acid, 100.1 parts of isophthalic acid, 52.3 parts of sebacic acid, 44.9 parts of ethylene glycol, 103.3 parts of neopentyl glycol, 56.3 parts of butyl ethyl propanediol, and 500.0 parts of ethyl acetate were charged into a reactor, and gradually heated to 160 to 240°C while stirring under a nitrogen stream to carry out an esterification reaction. The reaction was carried out at 240°C for 1 hour or more, and when the acid value became 15 or less, the pressure in the reactor was gradually reduced to 1 to 2 Torr. When a predetermined viscosity was reached, the reaction was stopped and the resin was taken out to obtain a polyester resin C. The polyester resin C has an aromatic ring structure of 24% by mass.

[Synthesis Example 5] (Preparation of Polyester Resin D Solution)
190.1 parts of hexahydrophthalic anhydride, 207.9 parts of castor oil, 38.6 parts of ethylene glycol, 63.4 parts of pentaerythritol, and 500.0 parts of ethyl acetate were charged into a reactor, and gradually heated to 160-240°C while stirring under a nitrogen stream to carry out an esterification reaction. The reaction was carried out at 195°C for 1 hour or more, and when the acid value became 15 or less, the pressure in the reactor was gradually reduced to 1-2 Torr. When a predetermined viscosity was reached, the reaction was stopped and the resin was taken out. Polyester resin D was obtained. Polyester resin D has 6 mass% of an alicyclic ring structure.

[Synthesis Example 6] (Preparation of Polyester Resin E Solution)
Comparative Synthesis Example 1 (Preparation of Polyester Resin E Solution)
100 parts of DL-lactide, 100 parts of L-lactide, 0.2 parts of sodium isethionate, 0.5 parts of tin octoate as a ring-opening polymerization catalyst, and 200.7 parts of ethyl acetate were charged into a four-neck flask and heated at 180° C. for 2 hours in a nitrogen atmosphere to cause ring-opening polymerization, thereby obtaining polyester resin E. Polyester resin E does not contain a constituent unit derived from a dibasic acid and a polyhydric alcohol. Polyester resin E does not have a ring structure.
[Synthesis Example 7] (Preparation of Polyester Resin F Solution)
Comparative Synthesis Example 1 (Preparation of Polyester Resin E Solution)
200 parts of meso-lactide, 0.2 parts of sodium isethionate, 0.5 parts of tin octoate as a ring-opening polymerization catalyst, and 200.7 parts of ethyl acetate were charged into a four-neck flask and heated at 180°C for 2 hours in a nitrogen atmosphere to cause ring-opening polymerization, thereby obtaining polyester resin E. Polyester resin F does not contain a constituent unit derived from a dibasic acid and a polyhydric alcohol. Polyester resin F does not have a ring structure.

<Production of printing ink>
[Production Example 1] (Production of printing ink R1)
As the binder resin, 32 parts of urethane resin solution PU1 (solid content 30%), 3 parts of vinyl chloride-vinyl acetate copolymer resin (manufactured by Nisshin Chemical Co., Ltd., Solvine TAO, solid content 30%, ethyl acetate solution), 0.5 parts of chlorinated polypropylene resin (manufactured by Nippon Paper Industries Co., Ltd., 370M, chlorine content 30%, solid content 50%) in terms of solid content, 0.8 parts of polyethylene wax (manufactured by Mitsui Chemicals, Inc., Hiwax 320P, average particle size 2.5 μm) in terms of solid content, 10 parts of indigo pigment (C.I. Pigment Blue 15:4), and 53.7 parts of a solution of methyl ethyl ketone (MEK) / n-propyl acetate (NPAC) / isopropanol (IPA) = 40 / 40 / 20 (mass ratio) were mixed and dispersed for 15 minutes with a bead mill to obtain printing ink R1.

[Production Examples 1 to 3] (Production of Printing Inks R1 to R3)
Printing inks R1 to R3 were obtained in the same manner as in Production Example 1, except that the raw materials and blending ratios shown in Table 1 were used.

The abbreviations and details of the raw materials in Table 1 are shown below.
Titanium oxide: Titanix JR-808, manufactured by Teika Corporation
Rosin maleic acid resin: rosin modified maleic acid resin. Arakawa Chemical Industries, Ltd., Malkid No. 5, solid content 30%, ethyl acetate solution, softening point 145°C, hydroxyl value 0 mgKOH/g
Polyamide resin: A polyamide resin containing 50% by mass or more of structural units derived from dimer acid made from oleic acid and linoleic acid as raw materials, and having an amine value of 3.5 mgKOH/g. Weight average molecular weight: 6,000, solid content: 30%, IPA solution.
Cellulose resin: Nitrocellulose. Solid content 30%, ethyl acetate/IPA solution, nitrogen content 11.5-12.2%, polymerization degree 35-45, hydroxyl value 175 mgKOH/g
・Chelating crosslinking agent: Organotitanium-based chelating crosslinking agent

[Example 1] (Preparation of overcoat agent S1)
6.6 parts of polyester resin A solution (solid content 50% by mass), 26.5 parts of vinyl chloride-vinyl acetate copolymer resin (manufactured by Nisshin Chemical Industry Co., Ltd., Solvine TAO, vinyl chloride 91% by mass, vinyl acetate 2% by mass, vinyl alcohol 7% by mass, solid content 50% by mass), 3.2 parts of XDI-TMP adduct (trimethylolpropane adduct of xylylene diisocyanate, NCO content 12% solid content 50% by mass), 1.8 parts of Kasozai DBS (dibutyl sebacate manufactured by Toyokuni Oil Co., Ltd.), and 61.8 parts of ethyl acetate were mixed and stirred for 30 minutes with a disper to obtain an overcoat agent S1 with a solid content of 20%. The XDI-TMP adduct was blended just before printing.

[Examples 2 to 17, Comparative Examples 1 to 4] (Preparation of overcoat agents S2 to S17, SS1 to SS4)
Overcoat agents S2 to S17 and SS1 to SS4 were obtained in the same manner as in Example 1, except that the raw materials and blending ratios shown in Table 2 were used.

The abbreviations and details of the raw materials in Table 2 are shown below.
TDI (toluene diisocyanate)-TMP adduct: solids content 50%, NCO content 13%
HDI (hexamethylene diisocyanate)-TMP adduct: solids content 50%, NCO content 13%
HDI-biuret: HDI-isocyanurate, solids content 50%, NCO content 23.5%
Vinyl chloride-hydroxyalkyl acrylate copolymer resin: Solvine VROH, manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride 73% by mass, vinyl acetate 16% by mass, hydroxyalkyl acrylate 11% by mass, solid content 50% by mass

<Creation of printed matter using printing ink R2 and overcoat agent S1>
Each of the printing ink R2 and the overcoat agent S1 was diluted with ethyl acetate to a viscosity of 15 seconds at 25° C. in a Zahn cup #3 (manufactured by Rigo Co., Ltd.).
The diluted printing ink R2 was applied to a 30 μm thick polypropylene (OPP) film using a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm at a printing speed of 40 m/min and a dryer temperature of 50° C. to obtain a printed film.
Next, the diluted overcoat agent S1 was applied to the surface of the printed film prepared above having the printed layer using a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm at a printing speed of 40 m/min and a dryer temperature of 50°C, thereby obtaining a printed matter having a configuration of plastic substrate/printed layer/transparent protective layer.

<Preparation of printed matter using each printing ink and overcoat agent>
Using the combinations of the printing inks and overcoat agents obtained above shown in Table 2, printed matter according to Examples 1 to 17 was produced in the same manner as in the production of the above printed matter.

<Characteristics evaluation>
The overcoat agents obtained in the above Examples and Comparative Examples and their printed matter were subjected to the following evaluations. The evaluation results are shown in Table 2.

<Gloss>
The gloss values of the printed matter produced in the above Examples and Comparative Examples were measured from the transparent protective layer side using a Micro-TRI-glossmeter manufactured by BYK-Gardner at an incident angle of 60° and a receiving angle of 60°. The evaluation criteria are shown below.
A (excellent): Gloss value is 90 or more.
B (Acceptable): Gloss value is 80 or more and less than 90.
C (unacceptable): The gloss value is less than 80.
A and B are within the range where there is no practical problem.

<Adhesion (tape adhesion resistance)>
For the printed matter produced in the above Examples and Comparative Examples, cellophane tape (12 mm wide) manufactured by Nichiban Co., Ltd. was applied to the transparent protective layer, and the degree of peeling of the printed layer or the transparent protective layer was evaluated when the tape was rapidly peeled off. The evaluation criteria are shown below.
A (Excellent): The printed layer or transparent protective layer does not peel off at all.
B (Fair): Less than 50% of the printed layer or transparent protective layer peels off.
C (unacceptable): 50% or more of the printed layer or transparent protective layer is peeled off.
A and B are within the range where there is no practical problem.

<Heat resistance>
The printed matter produced in the above examples and comparative examples was cut into pieces of 3 cm x 13 cm, and the glossy side of an aluminum foil (thickness 30 μm) cut to the same size was placed on the printed side of the printed matter. The aluminum foil was pressed with a pressure of 2 x 9.8 N/ ^cm2 at 120°C for 1 second using a Sentinel heat sealer, and the peeling of the printed layer or transparent protective layer when the aluminum foil was peeled off was visually judged. The evaluation criteria are shown below.
A (Excellent): No peeling at all at a seal bar temperature of 160°C.
B (Acceptable): Does not peel off at a seal bar temperature of 120°C, but peels off at 160°C.
C (unacceptable): Peeled off at a seal bar temperature of 120°C.
A and B are within the range where there is no practical problem.

<Blocking resistance>
The printed matter produced in the above Examples and Comparative Examples was evaluated for blocking resistance under the following conditions.
(Sample and Pressure)
Printed surface of OPP printed matter/non-corona treated surface of OPP substrate 10 kg/ ^cm2
(Static conditions) 40° C.-80% RH, 48 hours (Evaluation method) The printed surface and the substrate were peeled off, and the degree of peeling of the ink coating from the printed surface was visually judged.
(Judgment criteria)
A (Excellent): The ink film on the printed surface does not peel off at all and has low peeling resistance. B (Fair): The area of the ink film that has peeled off is between 5% and 20%. C (Unacceptable): The area of the ink film that has peeled off is 20% or more. A and B are within the range where there are no problems in practical use.

<Kneading resistance>
The printed matter produced in the above-mentioned Examples and Comparative Examples was kneaded 30 times with both hands and evaluated according to the following evaluation criteria. The measurement conditions were a test piece of 100 mm square.
A (Excellent): No peeling or lifting of the ink film. B (Fair): Some peeling or lifting of the ink film is observed, but no peeling. C (Unacceptable): Some peeling of the ink film. A and B are within the range of no practical problems.

<Abrasion resistance>
The coating strength of each of the printed matter produced in the above Examples and Comparative Examples was measured using a Gakushin-type friction fastness tester manufactured by Tester Sangyo Co., Ltd., and was evaluated according to the following evaluation criteria. The measurement conditions were: test piece 20 mm wide, load 500 g, 100 reciprocations, against Kanakin No. 3.
A (Excellent): No peeling of the ink film B (Fair): Peeling of the ink film over an area of 10% to less than 30% C (Unacceptable): Peeling of the ink film over an area of 30% or more A and B are within the range where there are no problems in practical use.

Reference Example 1: Evaluation of only surface-printed prints of printing ink
Each of the printing inks R2 was diluted with a mixed solvent of ethyl acetate/IPA (mass ratio 70/30) so that the ink would last for 15 seconds at 25° C. in a Zahn cup #3 (manufactured by Rigo Co., Ltd.).
The diluted printing ink R3 was applied to a 30 μm thick OPP film using a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm at a printing speed of 40 m/min and a dryer temperature of 50° C., to obtain a printed matter A1 with a surface print configuration.
The same evaluation as above was carried out on the printed matter A1 having a surface printing configuration, and the results were gloss: C, adhesion: A, heat resistance: A, blocking resistance: B, kneading resistance: B, and abrasion resistance: B.

Reference Example 2: Evaluation of Laminated Body
Each of the printing inks R2 was diluted with a mixed solvent of ethyl acetate/IPA (mass ratio 70/30) so that the ink would last for 15 seconds at 25° C. in a Zahn cup #3 (manufactured by Rigo Co., Ltd.).
The diluted printing ink R2 was applied to a 30 μm thick OPP film using a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm at a printing speed of 40 m/min and a dryer temperature of 50° C., to obtain a printed matter A2.
Next, using a dry laminator, a dry laminating adhesive (TM-340V/CAT-29B manufactured by Toyo-Morton) was applied onto the printed layer of printed matter A2, and then laminated with VMCPP (aluminum-vapor-deposited unoriented polypropylene film, thickness 25 μm) at a line speed of 40 m/min, to obtain a laminated body B1 laminated in the order of OPP substrate/printed layer/adhesive layer/VMCPP substrate.
The laminate B1 was evaluated in the same manner as above, and the results were gloss: B, adhesion: A, heat resistance: A, blocking resistance: A, kneading resistance: A, and abrasion resistance: A. The gloss was evaluated from the OPP substrate side.

The above evaluation results show that by using the overcoat agent according to an embodiment of the present invention, the gloss of the printed layer is improved to a level greater than that of a laminate laminated with a film, good adhesion and heat resistance are exhibited in the surface printing configuration of flexible packaging, and printed matter with good odor can be obtained.

Claims (7)

An overcoat agent for forming a transparent protective layer disposed on a print layer, the overcoat agent containing a binder resin and an isocyanate curing agent,
The overcoat agent comprises a binder resin comprising a vinyl chloride copolymer resin and a polyester resin having a ring structure, and the vinyl chloride copolymer resin is contained in an amount of 30 mass % or more based on the total mass of the binder resin. The overcoat agent according to claim 1, wherein the polyester resin having a ring structure includes a polyester resin having an aromatic ring structure. The overcoat agent according to claim 1 or 2, wherein the ring structure content in the total solid content of the overcoat agent is 0.5 to 10% by mass or less. The overcoat agent according to any one of claims 1 to 3, in which the mass ratio of the vinyl chloride copolymer resin to the polyester resin having a ring structure is 80:20 to 40:60. The overcoat agent according to any one of claims 1 to 4, wherein the polyester resin having a ring structure includes a vegetable oil-modified alkyd resin having a ring structure. The overcoat agent according to any one of claims 1 to 5, wherein the isocyanate curing agent has a ring structure. A printed matter having, in order, a substrate, a printed layer, and a transparent protective layer formed by the overcoat agent according to any one of claims 1 to 6.