JP7589626B2 - Active energy ray curable composition and laminate using same - Google Patents

Description

The present invention relates to an active energy ray-curable composition and a laminate using the same.

In recent years, in the field of packaging that uses paper substrates (also known as paper containers), much research has been conducted into printing color inks on various substrates and then applying a coating varnish to impart durability and aesthetic appeal to printed matter. With regard to paper container packaging, after printing, there are cases where glossiness or a matte finish is required for aesthetic reasons when the product is displayed in stores. In particular, there has been an increase in demand for printed matter with a matte finish in recent years.

Conventionally, solvent-based matte coating varnishes containing resins, matting agents, and solvents have been used for matte coating varnishes for paper packaging, with the aim of imparting a high-quality look through high matte properties. Generally, with solvent-based matte coating varnishes, the volume of the varnish film decreases as the solvent components evaporate from the varnish film during the drying process after printing, and the matting agent is oriented on the surface of the varnish film, resulting in a high matte effect, but on the other hand, they are poor in workability and environmental friendliness. Furthermore, with solvent-based matte coating varnishes, the solid content of the ink changes as the solvent components evaporate during printing, which raises concerns about viscosity changes during printing and the risk of environmental pollution due to volatilized solvent.

In recent years, solvent-free activated energy ray matte coating varnishes that improve workability and environmental friendliness have been developed. For example, Patent Document 1 proposes an activated energy ray curable coating varnish that contains a photopolymerizable acrylate monomer, resin beads, and a photoinitiator, in which the resin beads are made of resin beads with two types of average particle size, and that produces printed matter with excellent matte finish and abrasion resistance.

Patent Document 2 proposes a solventless active energy ray-curable composition containing an active energy ray-curable compound, an inorganic matting agent, and an aluminum chelate compound, characterized in that the inorganic matting agent is silica having an average particle size of 1 to 15 μm, the thixotropic coefficient at 25°C is 2 or less, and the viscosity at the coating environment temperature is 1000 mPa·s or less.

Patent Document 3 proposes an active energy ray-curable resin composition that contains an organic filler and a urethane (meth)acrylate compound obtained by reacting a polyol compound, a hydroxyl group-containing (meth)acrylate compound, and a polyisocyanate compound, in which the polyol compound contains a polyol compound having a weight average molecular weight of 60 to 300 and a polyol compound having a weight average molecular weight of 3,000 to 20,000, and the organic filler is a combination of a polyurethane filler and a polyethylene filler.

However, while the technologies disclosed in Patent Documents 1 and 2 above are solvent-free and have excellent workability and environmental friendliness, they do not have sufficient matte properties compared to the solvent-based matte coating varnishes that have traditionally been mainstream, and issues remain for use in paper packaging applications that require high matte properties in recent years.

In addition, while the composition of Patent Document 3 is considered to have sufficient matte properties from the viewpoint of cosmetic properties, it contains a solvent in order to impart coatability, and therefore has issues in terms of workability and environmental friendliness.

JP 2010-241954 A JP 2002-121210 A JP 2015-101609 A

The present invention aims to provide an active energy ray-curable composition for forming a cured layer that has excellent workability, environmental friendliness, and suitability for printing and other coating processes, and that has excellent adhesion to the substrate and matte properties (beautiful cosmetic properties) when printed and cured.

As a result of extensive research into the above-mentioned problems, the inventors discovered that the problems could be solved by using the active energy ray-curable composition described below, and thus completed the present invention.

That is, the present invention provides an active energy ray-curable composition containing a polyfunctional urethane (meth)acrylate, a monofunctional ethylenically unsaturated monomer, and resin fine particles,
The weight average molecular weight of the polyfunctional urethane (meth)acrylate is 1,000 to 7,000;
The composition does not contain an organic solvent or contains an organic solvent in an amount of 5% by mass or less based on the total mass of the composition;
The present invention relates to an active energy ray-curable composition, wherein the viscosity of the composition at 25° C. is 250 to 2500 mPa·s.

The present invention also relates to the above-mentioned active energy ray-curable composition, which further contains a photopolymerization initiator.

The present invention also relates to the above-mentioned active energy ray-curable composition, in which the multifunctional urethane (meth)acrylate has a structural unit derived from polyether.

The present invention also relates to the above-mentioned active energy ray-curable composition, in which the monofunctional ethylenically unsaturated monomer contains a hydroxyalkyl (meth)acrylate.

The present invention also relates to the above active energy ray-curable composition, which has a viscosity at 25°C of 500 to 1500 mPa·s.

The present invention also relates to the above-mentioned active energy ray-curable composition, in which the resin microparticles are urethane resin microparticles.

The present invention also relates to the above-mentioned active energy ray-curable composition for use on paper substrates.

The present invention also relates to a laminate having a printed layer and a cured layer formed from the above-mentioned active energy ray-curable composition on a paper substrate.

The present invention makes it possible to provide an active energy ray-curable composition for forming a cured layer that is excellent in workability, environmental friendliness, and suitability for printing and other coating processes, and that, when printed and cured, has excellent adhesion to the substrate and matte properties (beautiful appearance).

The following describes in detail the embodiments of the present invention. However, the following description of the components is merely an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these details as long as it does not exceed the gist of the invention.

The active energy ray-curable composition of the present invention is an active energy ray-curable composition containing a polyfunctional urethane (meth)acrylate, a monofunctional ethylenically unsaturated monomer, resin fine particles, and, if necessary, a photopolymerization initiator,
The weight average molecular weight of the polyfunctional urethane (meth)acrylate is 1,000 to 7,000;
The composition does not contain an organic solvent or contains an organic solvent in an amount of 5% by mass or less based on the total mass of the composition;
The viscosity of the composition at 25° C. is 250 to 2500 mPa·s. When the weight average molecular weight of the polyfunctional urethane (meth)acrylate is within the applicable range, the surface tackiness, blocking resistance, crease cracking resistance, etc. are improved, when the organic solvent in the total mass of the composition is 5 mass% or less, the viscosity stability is improved, and when the viscosity of the composition at 25° C. is 250 to 2500 mPa·s, the smoothness, penetration prevention, etc. are improved, and the printability and film properties of the printed matter are improved.

In the following description, (meth)acrylic and (meth)acrylate respectively mean methacrylic and/or acrylic, and methacrylate and/or acrylate. Also, (meth)acryloyl means methacryloyl and/or acryloyl. Also, the active energy ray-curable composition may be simply referred to as the "composition", but this has the same meaning.

(Polyfunctional urethane (meth)acrylate)
The weight average molecular weight of the polyfunctional urethane (meth)acrylate used in the present invention is 1000 to 7000. In addition to maintaining the viscosity of the composition appropriately and improving the coating suitability, excessive penetration into the paper substrate does not occur, and the cured layer formed from the active energy ray curable resin composition becomes uniform. Furthermore, the hardness of the cured layer is appropriately maintained and it does not crack. In addition, the blocking resistance is good due to the polyfunctionality. The weight average molecular weight is preferably 1500 to 5000, more preferably 1500 to 3500, and even more preferably 2000 to 3000. In addition, the number of functional groups of the polyfunctional urethane (meth)acrylate is preferably 2 to 4, more preferably 2 to 3, and even more preferably 2. Here, the number of functional groups refers to the number of polymerizable (meth)acrylate groups and other unsaturated double bond groups.

The weight average molecular weight mentioned above refers to a value measured by gel permeation chromatography, and can be measured, for example, using a GPC (gel permeation chromatography) "Shodex GPC System-21" manufactured by Showa Denko KK GPC (gel permeation chromatography) is a liquid chromatography that separates and quantifies substances dissolved in a solvent based on the difference in their molecular size. Tetrahydrofuran is preferably used as the solvent, and the weight average molecular weight is preferably determined in polystyrene equivalent.

The glass transition temperature (Tg) of the polyfunctional urethane (meth)acrylate is preferably 0 to 50°C, more preferably 5 to 40°C, even more preferably 10 to 35°C, and particularly preferably 15 to 30°C. The glass transition temperature is a value measured using a differential scanning calorimeter (DSC), and the midpoint between the endothermic start and end temperatures due to the glass transition in the DSC curve is taken as the glass transition temperature.

The polyfunctional urethane (meth)acrylate is preferably in the following form, for example, one obtained by reacting an isocyanate group-containing urethane prepolymer obtained by reacting a polyol with a polyisocyanate under conditions of excess isocyanate groups with a (meth)acrylate having a hydroxyl group, one obtained by reacting a polyisocyanate with a (meth)acrylate having a hydroxyl group, etc. Alternatively, it can also be obtained by reacting a hydroxyl group-containing urethane prepolymer obtained by reacting a polyol with a polyisocyanate under conditions of excess hydroxyl groups with a (meth)acrylate having an isocyanate group.

The above polyols, hydroxyl group-containing (meth)acrylates, and polyisocyanates are explained below.

<Polyol>
The polyol may be a known one, and suitable examples thereof include polyether polyol, polyester polyol, polyolefin polyol (polybutadiene polyol, polyisoprene polyol), polycarbonate polyol, polysiloxane polyol, (meth)acrylic polyol, etc., which may have an aliphatic structure or an alicyclic structure. Among these, polyether polyol is preferred. When polyether polyol is used, the multifunctional urethane (meth)acrylate has a structural unit derived from polyether. The polyether polyol is preferably, for example, polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, or a copolymer thereof. When the multifunctional urethane (meth)acrylate has a structural unit derived from polyether, the viscosity and coating suitability of the composition can be improved.

<Polyisocyanate>
As the polyisocyanate, known ones can be used, and examples thereof include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.
Examples of aromatic diisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, and 2,6-diisocyanate-benzyl chloride.
Examples of the aliphatic diisocyanate include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate.
Examples of alicyclic diisocyanates include cyclohexane-1,4-diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, and dimer diisocyanate in which the carboxy group of a dimer acid is converted into an isocyanate group.
These may form a trimer to form an isocyanurate ring structure. These polyisocyanates may be used alone or in combination of two or more kinds.
Among these, tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isocyanurates of hexamethylene diisocyanate are preferred.

<Hydroxyl Group-Containing (Meth)Acrylate>
Examples of hydroxyl group-containing (meth)acrylates include trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 1-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyethyl (meth)acrylate. Examples of the hydroxyl group-containing (meth)acrylic acid ester include hydroxyl group-containing (meth)acrylic acid esters such as octyl, cyclohexanedimethanol mono(meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, ethyl-α-(hydroxymethyl) (meth)acrylate, monofunctional glycerol (meth)acrylate, or (meth)acrylic acid esters having a hydroxyl group at the end obtained by ring-opening addition of these (meth)acrylates with ε-caprolactone lactone, and alkylene oxide-added (meth)acrylic acid esters obtained by repeatedly adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to the above-mentioned hydroxyl group-containing (meth)acrylates. Among these, those containing at least one selected from 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred.

<Monofunctional ethylenically unsaturated monomer>
Examples of the monofunctional ethylenically unsaturated monomers used in the present invention include (alkyl)(meth)acrylates having 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate, as well as benzyl (meth)acrylate, alkylphenols such as butylphenol, octylphenol, nonylphenol, and dodecylphenol, (meth)acrylates of ethylene oxide adducts, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, tricyclodecane monomethylol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, 2-hydroxypropyl ...propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-butoxypropyl (meth)acrylate, 2-hydroxy-3-methoxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate, acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, β-carboxyethyl (meth)acrylate, (meth)acrylic acid dimer, ω-carboxy-polycaprolactone mono(meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-vinylpyrrolidone, N-vinylformamide, (meth)acryloylmorpholine, and the like.
Among these, it is preferable to include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. The number of carbon atoms in the alkyl group is preferably 2 to 10 or 2 to 6, and more preferably 2 to 4.
The monofunctional ethylenically unsaturated monomer has the effect of significantly reducing the viscosity of the active energy ray curable composition, and improves the smoothness of the coating film. The monofunctional ethylenically unsaturated monomer is preferably contained in an amount of 30 to 60 mass%, more preferably 35 to 55 mass%, and even more preferably 40 to 50 mass% in the total mass of the active energy ray curable composition. The mass ratio of the polyfunctional urethane (meth)acrylate to the monofunctional ethylenically unsaturated monomer is preferably 10:90 to 40:60, and more preferably 15:85 to 30:70. The hydroxyalkyl (meth)acrylate is preferably contained in an amount of 70 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 85 to 100 mass% in the total mass of the monofunctional ethylenically unsaturated monomer.

<Difunctional ethylenically unsaturated monomer>
The composition of the present invention is also preferably a case where it contains a bifunctional ethylenically unsaturated monomer.The bifunctional ethylenically unsaturated monomer is preferably butanediol di(meth)acrylate, hexanediol di(meth)acrylate, octanediol di(meth)acrylate or other alkylene glycol di(meth)acrylate, polyethylene glycol 200 di(meth)acrylate (numbers indicate molecular weight), polyethylene glycol 300 di(meth)acrylate, polyethylene glycol 400 di(meth)acrylate, polyethylene glycol 600 di(meth)acrylate, polyethylene glycol 1000 di(meth)acrylate or other polyethylene glycol di(meth)acrylate, or tetraethylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, etc., and preferably contains a polyether structure.The amount of the bifunctional ethylenically unsaturated monomer is preferably 15% by mass or less, more preferably 7% by mass or less in the total mass of the composition.
The difunctional ethylenically unsaturated monomer does not include the above-mentioned polyfunctional urethane (meth)acrylate.

<Resin fine particles>
In the present invention, the resin fine particles are responsible for the matte function. The resin fine particles preferably have an average particle diameter of 1 to 10 μm, more preferably 1.5 to 8 μm, even more preferably 2 to 6 μm, and even more preferably 2 to 3 μm. The average particle diameter referred to here refers to the volume average particle diameter measured by a laser diffraction method, and can be measured, for example, using a T330EXII manufactured by Microtrack Bell.
Specific examples of suitable resin fine particles include urethane resin fine particles, silicone resin fine particles, melamine resin fine particles, melamine-benzoguanamine resin fine particles, acrylic resin fine particles (e.g., polymethyl methacrylate resin fine particles), acrylic-styrene copolymer resin fine particles, polycarbonate resin fine particles, polyethylene resin fine particles, polystyrene resin fine particles, and benzoguanamine resin fine particles. These may be used alone or in combination of two or more kinds. Among these, urethane resin fine particles are more preferable. The above-mentioned resin fine particles may be used in combination of two or more kinds as necessary.

The resin microparticles are preferably contained in an amount of 15 to 35% by mass, more preferably 20 to 30% by mass, and even more preferably 23 to 27% by mass, based on the total mass of the composition. The glass transition temperature of the resin microparticles is preferably -30 to 40°C, more preferably -20 to 30°C, and even more preferably -15 to 25°C. The glass transition temperature is a value measured using a differential scanning calorimeter (DSC), and the midpoint between the endothermic start and end temperatures based on the glass transition in the DSC curve is taken as the glass transition temperature.

Specific examples of urethane resin microparticles include crosslinked urethane beads such as Art Pearl C-1000 transparent, Art Pearl C-600 transparent, Art Pearl C-400 transparent, Art Pearl C-800, Art Pearl MM-120T, Art Pearl JB-800T, Art Pearl JB-600T, Art Pearl P-800T, and Art Pearl P-400T (manufactured by Negami Chemical Industries Co., Ltd.).

Specific examples of silicone resin particles include KMP-594, KMP-597, and KMP-
598, KMP-600, KMP-601, KMP-602 (manufactured by Shin-Etsu Chemical Co., Ltd.), Trefil E-506S, EP-9215 (manufactured by Dow Corning Toray Co., Ltd.), and the like.

Specific examples of melamine resin fine particles include Eposter SS, Eposter S, Eposter FS, Eposter S6, and Eposter S12 (manufactured by Nippon Shokubai Co., Ltd.).
A specific example of the melamine-benzoguanamine resin fine particles is Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.).

Specific examples of acrylic resin fine particles include Eposter MA1002, Eposter MA1004, Eposter MA1006, and Eposter MA1010 (manufactured by Nippon Shokubai Co., Ltd.), Tuftic FH-S005, Tuftic FH-S008, Tuftic FH-S010, Tuftic FH-S015, and Tuftic FH-S020 (manufactured by Toyobo Co., Ltd.), and Chemisnow M.
Examples of the polymerizable compound include X-80H3wT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MX-2000, and MX-3000 (manufactured by Soken Chemical Engineering Co., Ltd.).

Specific examples of acrylic-styrene copolymer resin microparticles include Eposter MA2003 (manufactured by Nippon Shokubai Co., Ltd.), FS-102, FS-201, FS-301, MG-451, MG-351 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.), etc.

Specific examples of polycarbonate resin microparticles include the microparticles described in JP-A-2014-125495, the microparticles obtained by the manufacturing method described in JP-A-2011-26471, and the microparticles obtained by the method described in JP-A-2001-213970.

Specific examples of polyethylene resin fine particles include Mipelon XM-220 and XM221U (manufactured by Mitsui Chemicals, Inc.), Flow Beads LE-1080 (manufactured by Sumitomo Seika Chemicals, Inc.), and the like.
Specific examples of polystyrene-based fine particles include Chemisnow SX-130H, SX-350H, and SX-500H (manufactured by Soken Chemical & Engineering Co., Ltd.).

Specific examples of benzoguanamine resin microparticles include Eposter MS, Eposter M05, and Eposter L15 (manufactured by Nippon Shokubai Co., Ltd.).

<Photopolymerization initiator>
The active energy ray curable composition of the present invention may contain a photopolymerization initiator. The photopolymerization initiator generates radicals by irradiation with active energy rays such as light, and initiates a crosslinking reaction and a polymerization reaction of the acrylate group of the polyfunctional urethane (meth)acrylate or the monofunctional ethylenically unsaturated monomer. Suitable examples of the photopolymerization initiator include acetophenone-based photopolymerization initiators, alkylphenone-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzophenone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. Among these, acetophenone-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators are preferred. The photopolymerization initiator is preferably contained in an amount of 1 to 10% by mass, more preferably 2 to 7% by mass, and even more preferably 3 to 5% by mass, based on the total mass of the composition.

Examples of the acetophenone-based photopolymerization initiator include acetophenone-based photopolymerization initiators such as 4-phenoxydichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and 2,2-dimethoxy-2-phenylacetophenone.

Examples of alkylphenone photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, and the like.

Benzoin-based photopolymerization initiators include benzoin, benzoin methyl ether, benzoin isoethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Benzophenone-based photopolymerization initiators (d-1) include benzophenone, 4-methylbenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, methyl-o-benzoylbenzoate, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3-dimethyl-4-methoxybenzophenone, etc. Among these, 4-methylbenzophenone is preferred.

Thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-diisopropylthioxanthone.

Anthraquinone-based photopolymerization initiators include α-acyloxime ester, benzil, methylbenzoyl formate ("Biacure 55"), 2-ethylanthraquinone, etc.

Examples of acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide ("OmniradTPO"), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide ("IRGACURE819"), etc.

The photopolymerization initiator may be used alone or in combination of two or more.

<Organic Solvent in Composition>
In order to solve the problems of the present invention, it is essential that the composition does not contain an organic solvent or that the organic solvent content is 5% by mass or less of the total mass of the composition. It is preferably 3% by mass or less, and more preferably 1.5% by mass or less. This is because printability is improved within this range. Examples of organic solvents that can be used include known solvents used in coating varnishes.

<Viscosity of Composition>
It is essential for the purpose of solving the problems of the present invention that the viscosity of the composition is 250 to 2500 mPa·s at 25°C. If the viscosity is within this range, excessive penetration into the paper substrate after coating by printing or the like is suppressed. In addition, the surface of the cured layer becomes a uniform film, and no spots or the like occur. The viscosity referred to here is a measured value according to the method described in JIS K5600-2, and can be measured, for example, using a cone-plate type viscometer using a cone with a cone diameter of 35 mm and a cone angle of 2° under a 25°C environment at a shear rate of 100 per second. The viscosity of the composition at 25°C is preferably 300 to 2000 mPa·s, and more preferably 500 to 1500 mPa·s.

(Additives)
The active energy ray-curable composition of the present invention can appropriately contain known additives. For example, a leveling agent, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, a sensitizer, a curing agent, a plasticizer, a wetting agent, an adhesion aid, an antifoaming agent, an antistatic agent, etc. can be used, and there are no particular limitations.

(Production of active energy ray-curable composition)
The active energy ray-curable composition can be produced by stirring a polyfunctional urethane (meth)acrylate having a weight average molecular weight of 1000 to 7000, a monofunctional ethylenically unsaturated monomer, resin fine particles, and a photopolymerization initiator for about 30 minutes to 3 hours using a bladed stirrer (disper), etc. If mixing is difficult and the viscosity, etc., tends to become non-uniform, a roller mill, ball mill, pebble mill, attritor, sand mill, etc. may be used.

If the active energy ray-curable composition of the present invention contains air bubbles or unexpectedly large particles, it is preferable to remove them by filtration or the like, as they will deteriorate the quality of the printed matter. Conventional filters can be used.

(Manufacture of Laminate)
The method for producing the laminate of the present invention is not particularly limited, but it is preferably produced by printing/coating the active energy ray-curable composition on a paper substrate or a film substrate and curing it. Alternatively, a printed layer made of a printing ink composition may be formed on the substrate, and the active energy ray-curable composition of the present invention may be printed/coated on the printed layer and cured to form a laminate.

The printing/coating method for the active energy ray-curable composition is not particularly limited, and examples include wet coating methods such as spray, shower, dipping, flow coating, gravure printing, flexographic printing, roll, spin, dispenser, inkjet printing, and screen printing.

Examples of active energy rays include ultraviolet rays such as far ultraviolet rays, ultraviolet rays, and near ultraviolet rays. On the other hand, it is also possible to use electron beams or proton beams, in which case curing can be achieved without using a photopolymerization initiator, but curing by ultraviolet irradiation is preferred in terms of curing speed, ease of obtaining irradiation equipment, cost, etc.

The method of curing by ultraviolet irradiation may be carried out using a high pressure mercury lamp, ultra-high pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, chemical lamp, electrodeless discharge lamp, LED or the like that emits light in the wavelength range of 150 to 450 nm, with an integrated light quantity of 30 to 5000 mJ/cm ² , preferably 100 to 1000 mJ/cm ^2. After ultraviolet irradiation, heating may be carried out as necessary to ensure complete curing.

The active energy ray-curable composition can be printed or coated to form a layer, and then irradiated with active energy rays to form a cured layer.
The film thickness (film thickness after curing) when the active energy ray-curable composition is printed or coated is usually preferably 1 to 50 μm, more preferably 1 to 30 μm, even more preferably 1 to 20 μm, still more preferably 1 to 10 μm, and particularly preferably 1 to 5 μm.

<Paper base material>
The paper substrate used in the present invention is preferably ordinary paper or cardboard, and although there is no particular designation for the thickness, a substrate having a thickness of 0.2 mm to 1.0 mm can be preferably used, and the printed surface may be corona-treated. In addition, the surface of the paper substrate may be vapor-deposited with a metal such as aluminum for the purpose of imparting design, and may further be surface-coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and may further be surface-treated, such as corona treatment. For example, coated cardboard and Marie-coated paper are preferably used.

<Film substrate>
The film substrate used in the present invention is preferably a normal PET (polyethylene terephthalate) or PVC (polyvinyl chloride), and is not particularly limited. The film thickness is preferably 0.02 mm to 1.0 mm, and the substrate surface may be corona-treated. The film substrate may be surface-coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and may further be surface-treated, such as corona treatment. Examples include Cosmoshine A4300 (manufactured by Toyobo), E5101 (manufactured by Toyobo), and Crisper K2323 (manufactured by Toyobo).

<Printing ink composition>
Examples of the printing ink composition include known gravure ink compositions, flexographic ink compositions, ultraviolet-curable flexographic ink compositions, offset ink compositions, ultraviolet-curable offset ink compositions, and other ink compositions, and any printing ink composition may be used. Among them, when an ultraviolet-curable offset ink composition or an ultraviolet-curable flexographic ink composition is used, if an active energy ray-curable composition is laminated, a curing reaction caused by ultraviolet light or the like occurs between the layers, improving adhesion. Therefore, as the printing ink composition, an ultraviolet-curable offset ink composition or an ultraviolet-curable flexographic ink composition is more preferable.

<Printing with printing ink>
Known methods can be used as the printing method for the printing ink composition. Examples include gravure printing, flexographic printing, offset printing, and screen printing. The thickness of the ink layer is preferably 0.1 to 15 μm, and more preferably 0.5 to 12 μm. The printing ink composition may be either an organic solvent-based or water-based ink composition, or may be an ultraviolet-curable ink composition. The ink layer may be formed by combining the above printing ink compositions, and the printing layer can be formed by drying or ultraviolet curing after printing.

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 percentages in the present invention represent parts by mass and percentages by mass unless otherwise noted.

(Weight average molecular weight)
The weight average molecular weight was determined by measuring the molecular weight distribution using a GPC (gel permeation chromatography) device (HLC-8220 manufactured by Tosoh Corporation) and calculating the molecular weight converted using polystyrene as a standard substance. The measurement conditions are shown below.
Columns: The following columns were used in series connection:
Tosoh Corporation TSKgel Super AW2500
Tosoh Corporation TSKgel Super AW3000
Tosoh Corporation TSKgel Super AW4000
Tosoh Corporation TSK gelguard column Super AWH
Detector: RI (differential refractometer)
Measurement conditions: column temperature 40°C
Eluent: tetrahydrofuran Flow rate: 1.0 mL/min

(Glass Transition Temperature)
The glass transition temperature (Tg) was determined by DSC (differential scanning calorimetry). The measurement was performed using a Rigaku Corporation DSC8231 instrument, with a measurement temperature range of −70 to 150° C., a heating rate of 10° C./min, and the midpoint between the endothermic start and end temperatures due to the glass transition in the DSC curve was taken as the glass transition temperature.

[Synthesis Example 1: Synthesis of urethane acrylate UA1]
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 262 parts (1 mole) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 2000 parts (2 moles) of polytetramethylene ether glycol (product name: PTMG1000 manufactured by Mitsubishi Chemical Corporation), 232 parts (2 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 1.247 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80°C for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40°C to obtain 2262 parts of a pale yellow liquid (UA1). The weight average molecular weight of the urethane acrylate UA1 was 2200, the Tg was 25°C, and the number of functional groups was 2.

[Synthesis Example 2: Synthesis of urethane acrylate UA2]
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 79 parts (0.3 moles) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 11,750 parts (0.6 moles) of polytetramethylene ether glycol (product name: PTMG3000 manufactured by Mitsubishi Chemical Corporation), 70 parts (0.6 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 0.97 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80 ° C. for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40 ° C. to obtain 1,949 parts of a pale yellow liquid (UA2). The urethane acrylate UA2 had a weight average molecular weight of 6,200, a Tg of 9° C., and two functional groups.

[Synthesis Example 3: Synthesis of urethane acrylate UA3]
A 3L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 500 parts (1 mole) of a hexamethylene diisocyanate trimer (product name: Sumidur N3390 manufactured by Sumika Bayer Urethane Co., Ltd.), 675 parts (3 moles) of polytetramethylene ether glycol (product name: PTMG250 manufactured by Mitsubishi Chemical Co., Ltd.), 348 parts (3 moles) of 2-hydroxyethyl acrylate (product name: Hydroxyethyl Acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 0.76 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80°C for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum as the reaction was terminated, the mixture was cooled to 40°C, and 1523 parts of a pale yellow liquid (UA3) was obtained. The weight average molecular weight of the urethane acrylate UA3 was 1
200, Tg was 35° C., and the number of functional groups was 3.

[Synthesis Example 4: Synthesis of urethane acrylate UA4]
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 158 parts (0.6 moles) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 1680 parts (1.2 moles) of polybutadiene having hydroxyl groups at both ends (product name: NISSO-PBG-1000 manufactured by Nippon Soda Co., Ltd.), 139 parts (1.2 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 0.99 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air, and reacted at 80 ° C. for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40 ° C. to obtain 1977 parts of a pale yellow liquid (UA4). The urethane acrylate UA4 had a weight average molecular weight of 3,000, a Tg of 21° C., and two functional groups.

[Synthesis Example 5: Synthesis of urethane acrylate UA5]
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 131 parts (0.5 moles) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 2000 parts (1.0 moles) of polytetramethylene ether glycol (product name: PTMG2000 manufactured by Mitsubishi Chemical Corporation), 116 parts (1.0 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 1.12 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80 ° C. for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40 ° C. to obtain 1977 parts of a pale yellow liquid (UA4). The urethane acrylate UA5 had a weight average molecular weight of 3,500, a Tg of 19° C., and two functional groups.

Comparative Synthesis Example 1: Synthesis of urethane acrylate UA6
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 66 parts (0.25 moles) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 2000 parts (0.5 moles) of polytetramethylene ether glycol (product name: PTMG4000 manufactured by Mitsubishi Chemical Corporation), 58 parts (0.5 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 1.04 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80 ° C. for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40 ° C. to obtain 2077 parts of a pale yellow liquid (UA5). The urethane acrylate UA6 had a weight average molecular weight of 9,000, a Tg of -9°C, and two functional groups.

Comparative Synthesis Example 2: Synthesis of urethane acrylate UA7
A 4L separable four-neck flask equipped with a stirrer, thermometer, and cooling tube was charged with 576 parts (2.2 moles) of dicyclohexylmethane 4,4'-diisocyanate (product name: Desmodur W manufactured by Sumika Covestro Urethane Co., Ltd.), 990 parts (4.4 moles) of polytetramethylene ether glycol (product name: PTMG250 manufactured by Mitsubishi Chemical Corporation), 511 parts (4.4 moles) of 2-hydroxyethyl acrylate (product name: hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 1.06 parts (500 ppm) of p-methoxyphenol, and the mixture was stirred while feeding air and reacted at 80°C for 4 hours. After confirming the disappearance of the peak due to the isocyanate group in the IR spectrum and terminating the reaction, the mixture was cooled to 40°C to obtain 2124 parts of a pale yellow liquid (UA6). The weight average molecular weight of the urethane acrylate UA7 was 700, the Tg was 44°C, and the number of functional groups was 2.
Table 1 summarizes the urethane (meth)acrylates synthesized above.

(Example 1: Preparation of active energy ray-curable composition S1)
12 parts of urethane acrylate UA1, 47 parts of 4-HBA (4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemicals), 25 parts of ART PEARL MM-120T (urethane-based fine particles, average particle size 2 μm, glass transition temperature “Tg” 22° C., manufactured by Negami Chemical Industrial Co., Ltd.), 4 parts of Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM) as a photopolymerization initiator, and 12 parts of a silicone-based defoamer as an additive were mixed and stirred with a bladed stirrer for 90 minutes to obtain an active energy ray-curable composition S1.

(Examples 2 to 21: Preparation of active energy ray-curable compositions S2 to S21)
Active energy ray-curable compositions S2 to S21 were obtained in the same manner as in Example 1, except that the raw materials shown in Table 2-1 were used in the blending ratios shown therein.

(Comparative Examples 1 to 6: Preparation of Active Energy Ray-Curable Compositions T1 to T6)
Active energy ray-curable compositions T1 to T6 were obtained in the same manner as in Example 1, except that the raw materials shown in Table 2-2 were used in the described blending ratios.

The abbreviations of the raw materials in Tables 2-1 to 2-2 are as follows:
<Monofunctional ethylenically unsaturated monomer>
HEA (2-hydroxyethyl acrylate, manufactured by Osaka Organic Chemicals)
LA (lauryl acrylate, manufactured by Osaka Organic Co., Ltd.)
<Difunctional ethylenically unsaturated monomer>
TEGDA (Tetraethylene glycol diacrylate, manufactured by Osaka Organic Chemicals)
<Resin fine particles>
・ART PEARL C-800 transparent (urethane resin fine particles, average particle size 6μm, Tg=-13℃, manufactured by Negami Kogyo Co., Ltd.)
・ART PEARL C-1000 transparent (urethane resin fine particles, average particle size 3μm, Tg=-13℃, manufactured by Negami Kogyo Co., Ltd.)
・ART PEARL J-4P (acrylic resin fine particles, average particle size 2.2 μm, manufactured by Negami Kogyo Co., Ltd.)
・Silosphere C-1504 (spherical silica, average particle size 4.5 μm, manufactured by Fuji Silysia Corporation)
<Photopolymerization initiator>
Omnirad 1173 (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM)
<Organic Solvent>
PGM-AC (propylene glycol monomethyl ether acetate, manufactured by Toyo Petrochemical Co., Ltd.)

(Example 22)
<Coating of active energy ray-curable composition S1>
Using a sheet-fed printing press "Lithrone 26 (manufactured by Komori Corporation)," a UV-curable offset ink "FD Carton X Ink M (manufactured by Toyo Ink Co., Ltd., containing a multifunctional (meth)acrylic monomer with three or more functionalities)" was printed on a paper substrate, Aurora Coat (coated paper high gloss type, paper thickness 81 μm, manufactured by Nippon Paper Industries Co., Ltd.), so that the ink density was 1.75 (measuring device: X-Rite eXact (manufactured by X-Rite Co., Ltd.), conditions: Illuminant D50, standard observer 2°, density status E, no filter), and cured with a UV lamp. The printing speed was 8000 sheets/hour, the types of UV lamps were two air-cooled metal halide lamps and one high-pressure mercury lamp, and the intensity of the UV lamps was 160 W/cm for all three lamps (accumulated light quantity 450 mJ/cm ² ).
Next, the active energy ray curable composition S1 was applied onto the printed matter of FD Carton X Ink M obtained above using a flexographic coating unit of Lithrone 26, and cured with a UV lamp to obtain a laminate G1. The anilox roll of the coating unit had a trihelical engraved pattern, a line count of 90 lines/inch, and a cell volume of 25 ml/ ^m2 . During flexographic coating, the printing speed was 8000 sheets/hour, and the temperature was controlled so that the liquid temperature of S1 was 25°C. The type, number, and intensity of the UV lamp were the same as those of the curing conditions for FD Carton X Ink M described above.

(Examples 23 to 43)
In the same manner as in Example 22, laminates G2 to G22 (Examples) were obtained using the active energy ray-curable compositions S2 to S23 shown in Table 2-1.

(Example 43)
A laminate G22 was obtained in the same manner as in Example 22, except that the paper substrate (Aurora Coat, (coated paper high gloss type, paper thickness 81 μm, manufactured by Nippon Paper Industries Co., Ltd.) used in Example 22 was changed to the paper substrate (U-Lite, (coated paper matte type, paper thickness 79 μm, manufactured by Nippon Paper Industries Co., Ltd.) shown in Table 3-1.

(Example 45)
A laminate G23 was obtained in the same manner as in Example 22, except that the paper substrate (Aurora Coat, (coated paper high gloss type, paper thickness 81 μm, manufactured by Nippon Paper Industries Co., Ltd.) used in Example 22 was changed to a film substrate (Crisper K2323, polyester film, thickness 75 μm, manufactured by Toyobo Co., Ltd.) described in Table 3-1.

(Comparative Examples 7 to 12)
Laminates H1 to H6 (Comparative Examples) were obtained in the same manner as in Example 22, except that the active energy ray-curable compositions T1 to T6 shown in Table 2-2 were used.

(evaluation)
The active energy ray curable compositions and laminates obtained in the Examples and Comparative Examples were evaluated for viscosity stability, penetration prevention, smoothness, matte finish, surface tackiness, blocking resistance, and adhesion as described below. The evaluation results are shown in Tables 3-1 and 3-2.

<Viscosity stability>
The viscosity change rate was measured for the active energy ray curable compositions obtained in the examples and comparative examples. The viscosity change rate is a value obtained by measuring the viscosity before and after heating, dividing the viscosity after heating by the viscosity before heating, and expressing the value as a percentage (%). The above-mentioned heating is a process in which the active energy ray curable composition is poured into a cylindrical metal container with an inner diameter of 9.6 cm and a height of 3.0 cm to a thickness of 1 cm, and then left in a 40°C environment for 30 minutes. The viscosity was measured using a cone-plate type viscometer under a liquid temperature condition of 25°C. The evaluation criteria are as follows.
5 (Excellent): Viscosity change rate of 0% or more but less than 3% 4 (Good): Viscosity change rate of 3% or more but less than 6% 3 (Acceptable): Viscosity change rate of 6% or more but less than 9% 2 (Unacceptable): Viscosity change rate of 9% or more but less than 12% 1 (Poor): Viscosity change rate of 12% or more Note that ratings of 3, 4 and 5 are suitable for practical use.

<Seeping prevention>
The active energy ray curable compositions obtained in the Examples and Comparative Examples were coated on the non-image areas of the UV offset ink instead of on the image areas when preparing a laminate, and the time required for the active energy ray curable composition to penetrate into the substrate and develop a mottled pattern was measured on the printed matter having a cured layer that was discharged without being irradiated with a UV lamp. Note that if the UV lamp is irradiated after coating in the coating unit, the penetration phenomenon stops at that point, so the UV lamp was not irradiated in this evaluation. The evaluation criteria are as follows.
5 (Excellent): 15 seconds or more; 4 (Good): 12 seconds or more but less than 15 seconds; 3 (Fair): 9 seconds or more but less than 12 seconds; 2 (Unacceptable): 6 seconds or more but less than 9 seconds; 1 (Poor): Less than 6 seconds. Note that ratings of 3, 4 and 5 are usable for practical use.

<Smoothness>
The arithmetic mean roughness Ra of the cured layer surface of the laminates obtained in the examples and comparative examples was measured. The Ra was measured using a laser microscope (VK-X100 manufactured by Keyence Corporation, magnification 1000 times). The evaluation criteria are as follows.
5 (excellent): Ra less than 1.0 μm 4 (good): Ra 1.0 μm or more and less than 1.5 μm 3 (passable): Ra 1.5 μm or more and less than 2.0 μm 2 (unacceptable): Ra 2.0 μm or more and less than 2.5 μm 1 (poor): Ra 2.5 μm or more Note that ratings 3, 4 and 5 are suitable for practical use.

<Matte property>
The gloss of the cured layer surface was measured for the laminates obtained in the examples and comparative examples. The gloss was measured at an incident angle of 60 degrees. The evaluation criteria were as follows. The gloss was measured using Micro Trigloss manufactured by BYK.
5 (excellent): gloss value less than 6 4 (good): gloss value 6 or more but less than 8 3 (passable): gloss value 8 or more but less than 10 2 (unacceptable): gloss value 10 or more but less than 12 1 (poor): gloss value 12 or more Note that ratings of 3, 4 and 5 are suitable for practical use.

<Surface tackiness>
The laminates obtained in the Examples and Comparative Examples were evaluated for the presence or absence of surface tack (stickiness) of the cured film (cured layer). A finger was pressed firmly against the cured film for 10 seconds, and then the finger was removed from the film surface. Thereafter, the degree of fingerprint adhesion to the cured layer surface and stickiness to the touch of the finger were measured. The evaluation criteria were as follows:
5 (Excellent): No fingerprints and no stickiness4 (Good): Slight fingerprints but no stickiness3 (Fair): Fingerprints but no stickiness2 (Poor): Fingerprints and slight stickiness1 (Poor): Fingerprints and stickiness.
The practically usable ratings are 3, 4 and 5.

<Blocking resistance>
The laminates obtained in the examples and comparative examples were stacked so that the cured layers were in contact with each other, a load of 10 kgf/ ^cm2 was applied, and the laminates were left in an environment of 40°C and 80% RH for 24 hours, and then removed to evaluate the state of blocking (a phenomenon in which one cured layer adheres to the other cured layer and transfers when the cured layers are pulled away from each other from a state in which they are in contact with each other). Regarding the peel resistance, a test piece of 25 mm x 100 mm was prepared, and left in an atmosphere of 23°C and 50% RH for 30 minutes, and then the 180°C peel strength (N/25 mm) was measured at a peel speed of 30 mm/min. The evaluation criteria are as follows.
5 (Excellent): No blocking (no metastasis)
Peel resistance less than 0.01 N/25 mm 4 (Good): No blocking (no transfer)
Peel resistance: 0.01 N/25 mm or more and less than 0.03 N/25 mm;
3 (OK): No blocking (no metastasis)
Peel resistance: 0.03 N/25 mm or more and less than 0.05 N/25 mm;
2 (Not possible): Blocking occurs (transition occurs)
Peel resistance 0.05 N/25 mm or more 1 (poor): Blocking occurs and the substrate is damaged during peeling
Peel resistance: 0.05 N/25 mm or more. Evaluations of 3, 4 and 5 indicate that the film can be used in practical applications.

<Crack resistance>
For the laminates obtained in the examples and comparative examples, the cured layer was folded in a mountain shape with a bending radius of 2 mm, and then a peeling test was performed on the folded portion using a 100 mm long adhesive tape (LP12, manufactured by Nichiban Co., Ltd.), and the total length of the portion where the cured layer peeled off was measured. The evaluation criteria are as follows.
5 (Excellent): peel length less than 1 mm; 4 (Good): peel length 1 mm or more and less than 5 mm; 3 (Acceptable): peel length 5 mm or more and less than 9 mm; 2 (Unacceptable): peel length 9 mm or more and less than 13 mm; 1 (Poor): peel length 13 mm or more. Evaluations of 3, 4 and 5 indicate that the film can be used in practical applications.

<Adhesiveness>
For the laminates obtained in the Examples and Comparative Examples, 100 cross-cuts of 1 ^mm2 were made on the cured layer using a checkerboard peeling test tool. Then, adhesive tape (LP24, manufactured by Nichiban Co., Ltd.) was attached to the cross-cuts and peeled off in a 90-degree direction, and the number of remaining checkerboards on the cured layer was counted. The evaluation criteria were as follows:
5 (Excellent): Number of remaining squares = 96-100 4 (Good): Number of remaining squares = 91-95 3 (Fair): Number of remaining squares = 86-90 2 (Unacceptable): Number of remaining squares = 81-85 1 (Poor): Number of remaining squares = 80 or less Note that ratings of 3, 4 and 5 are suitable for practical use.

A practically usable active energy ray curable composition is one that simultaneously satisfies stable printability and good film properties. In other words, it simultaneously satisfies a rating of 3 or higher for viscosity stability, and a rating of 3 or higher for all of the following properties: penetration prevention, smoothness, matte finish, surface tackiness, blocking resistance, crease cracking resistance, and adhesion.

From the above examples, we have found a method for imparting sufficient viscosity stability and stable printability by reducing the amount of solvent in the active energy ray-curable composition. Furthermore, by setting the molecular weight of the urethane (meth)acrylate to 1,000 to 7,000, we have been able to obtain excellent cured film properties.

Since it does not contain organic solvents or uses only a small amount of them, this active energy ray-curable composition is useful as a low-gloss coating agent with low environmental impact.

Claims (6)

An active energy ray-curable composition comprising a polyfunctional urethane (meth)acrylate, a monofunctional ethylenically unsaturated monomer, and resin fine particles,
The weight average molecular weight of the polyfunctional urethane (meth)acrylate is 1,000 to 7,000;
The composition does not contain an organic solvent or contains an organic solvent in an amount of 5% by mass or less based on the total mass of the composition;
The viscosity of the composition at 25°C is 250 to 2500 mPa s,
An active energy ray-curable composition for use on a paper substrate. The active energy ray-curable composition according to claim 1, further comprising a photopolymerization initiator. The active energy ray-curable composition according to claim 1 or 2, wherein the multifunctional urethane (meth)acrylate has a structural unit derived from polyether. The active energy ray-curable composition according to any one of claims 1 to 3 , having a viscosity at 25°C of 500 to 1500 mPa·s. 5. The active energy ray-curable composition according to claim 1, wherein the resin fine particles are urethane resin fine particles. A laminate having a printed layer and a cured layer formed from the active energy ray-curable composition according to any one of claims 1 to 5 on a paper substrate.