JP7847469B2 - Method for manufacturing active energy ray-curable coating agent and laminate - Google Patents

Description

This invention relates to an active energy ray curable coating agent and a method for manufacturing a laminate using the coating agent.

Decorative sheets with wood grain patterns or other designs are frequently used on the surfaces of building interior materials and fixtures. The surface of these decorative sheets is coated with a protective and aesthetically pleasing coating agent. These coating agents are primarily required to have "impact resistance" to prevent cracking from falling heavy objects, "scratch resistance" to prevent damage from scratches and abrasions, and "stain resistance" to prevent staining from various contaminants.
Furthermore, in recent years there has been a growing demand for the adoption of carbon-neutral materials (biomass) made from plant-derived raw materials that suppress carbon dioxide emissions into the environment.
On the other hand, low-gloss coating agents containing specific acrylic acrylates and silica (see, for example, Patent Document 1), coating compositions containing specific acrylic (meth)acrylate resins, compounds having an acryloyl group and a siloxane skeleton and/or a fluoroalkyl group, and silica (see, for example, Patent Document 2), and active energy ray curable compositions using specific silica and silicone (meth)acrylate in combination (see, for example, Patent Document 3) are known.
However, in recent years, there has been a demand for even greater durability in building materials, and currently, a more high-performance biomass-type coating agent that combines impact resistance, scratch resistance, and stain resistance has not yet been obtained.

Patent No. 6637950 Patent No. 6697771 Patent No. 5144881

The problem that this invention aims to solve is to provide an active energy ray curable coating agent using biomass raw materials that possesses impact resistance, scratch resistance, and stain resistance, and a method for manufacturing a laminate using the active energy ray curable coating agent.

The inventors have found that an active energy ray-curable coating agent containing acrylic (meth)acrylate and acrylate having a glycerin skeleton in a specific ratio range solves the aforementioned problem.

In other words, the present invention provides an active energy ray curable coating agent containing an acrylic (meth)acrylate and an acrylate having a glycerin skeleton, characterized in that the mass ratio of the acrylic (meth)acrylate to the acrylate having a glycerin skeleton is in the range of 80:20 to 20:80.

Furthermore, the present invention provides an active energy ray curable coating agent containing 1 to 10% by mass of a cellulose-based resin having a number average molecular weight of 10,000 to 80,000, relative to the total mass of the active energy ray curable coating agent.

Furthermore, the present invention provides an active energy ray curable coating agent having a double bond equivalent of 200 to 750 g/mol of acrylic (meth)acrylate and a weight-average molecular weight of 10,000 to 100,000.

Furthermore, the present invention provides an active energy ray curable coating agent in which the acrylate having a glycerin skeleton is a compound having 2 to 4 (meth)acryloyl groups.

Furthermore, the present invention provides a method for manufacturing a laminate, characterized by comprising the steps of (I) forming a coating film of the active energy ray-curable coating agent on a substrate, and (II) irradiating the coating film with active energy rays, in this order.

The active energy ray curing coating agent of the present invention utilizes biomass raw materials and possesses impact resistance, scratch resistance, and stain resistance.

The active energy ray curable coating agent of the present invention is an active energy ray curable coating agent containing acrylic (meth)acrylate and acrylate having a glycerin skeleton, wherein the mass ratio of the acrylic (meth)acrylate to the acrylate having a glycerin skeleton is in the range of 80:20 to 20:80.

In this invention, "(meth)acrylate" refers to either or both acrylate and methacrylate.

(Acrylic (meth)acrylate)
The acrylic (meth)acrylate used in the active energy ray curable coating agent of the present invention preferably has a double bond equivalent in the range of 200 to 750 g/mol.
If the double bond equivalent of the acrylic (meth)acrylate is 200 g/mol or more, volume shrinkage during curing tends to be suppressed, making it less likely for the coating film to bend or crack due to distortion, and also suppressing the decrease in workability due to dense crosslinking.
Furthermore, if the concentration is 750 g/mol or less, there will be no shortage of reactive groups and the hardness after the reaction will be maintained. A concentration in the range of 200 to 600 g/mol is more preferable, and a concentration in the range of 250 to 550 g/mol is even more preferable.
Furthermore, the double bond equivalent of the acrylic (meth)acrylate resin is defined by the following formula.
"Double bond equivalent" = "Molecular weight of one molecule of acrylic (meth)acrylate resin" / "Number of double bonds"
Furthermore, the weight-uniform molecular weight of the acrylic (meth)acrylate is preferably in the range of 10,000 to 100,000.
If the weight-average molecular weight of the acrylic (meth)acrylate is 10,000 or more, tack is less likely to remain on the coating film, and tack-free coating can be easily achieved through the drying process alone. If it is 100,000 or less, the viscosity of the composition will not become too high, and the problem of insufficient coating amount due to excessive dilution during coating can be avoided. Furthermore, from the viewpoint of workability, a molecular weight of 10,000 to 50,000 is more preferable, and a molecular weight in the range of 10,000 to 30,000 is even more preferable.
The aforementioned weight-average molecular weight is determined by measurement using GPC (Glycerin Propagation) on a polystyrene basis.

Furthermore, the glass transition temperature (Tg) of the acrylic (meth)acrylate is preferably in the range of 40 to 130°C. If it is 40°C or higher, sufficient strength can be obtained after curing when it is used as a coating film, and if it is 130°C or lower, the tendency for brittleness to appear and a decrease in processability when it is used as a coating film can be suppressed. Furthermore, the hydroxyl value of the acrylic (meth)acrylate is preferably in the range of 5 to 300 mg KOH/g. If it is 5 mg KOH/g or higher, when used in combination with a matting agent such as wet silica, the dispersion of the matting agent does not decrease and it is easier to maintain a low gloss, and if it is 300 mg KOH/g or lower, the tendency for a decrease in stain resistance can be suppressed.
The glass transition temperature (Tg) was measured using a differential scanning calorimeter under a nitrogen atmosphere and with a cooling device, scanning was performed within a temperature range of -80 to 450°C and a heating rate of 10°C/min.

(Acrylate with a glycerin skeleton)
Furthermore, the acrylate having a glycerin skeleton used in the active energy ray curable coating agent of the present invention is preferably a compound having 2 to 4 (meth)acryloyl groups.
Specifically, these include glycerin diacrylate, glycerin dimethacrylate, ethylene oxide-modified glycerin diacrylate, ethylene oxide-modified glycerin dimethacrylate, propylene oxide-modified glycerin diacrylate, propylene oxide-modified glycerin dimethacrylate, glycerin triacrylate, glycerin trimethacrylate, ethylene oxide-modified glycerin triacrylate, ethylene oxide-modified glycerin trimethacrylate, propylene oxide-modified glycerin triacrylate, propylene oxide-modified glycerin trimethacrylate, diglycerin acrylate, ethylene oxide-modified diglycerin acrylate, and propylene oxide-modified diglycerin acrylate.
As commercially available products, preferred are Toagosei Co., Ltd.'s glycerin diacrylate "Aronics M-920 (45% plant-derived material ratio)" and glycerin triacrylate "Aronics M-930 (37% plant-derived material ratio)," which have been certified by the Japan Organic Resources Association as having a biomass content (percentage of biomass raw materials contained in the product by dry weight) of 35%. The aforementioned plant-derived material ratio is calculated as molecular weight of the plant-derived raw material skeleton ÷ total molecular weight × 100, based on the description in Toagosei Group Research Annual Report 26 TREND 2020 No. 23. In addition, as the ethylene oxide-modified diglycerin acrylate, Toagosei Co., Ltd.'s "Aronics M-460 (30% plant-derived material ratio)" can be mentioned.

The active energy ray curable coating agent of the present invention must have a mass ratio of acrylic (meth)acrylate to acrylate having a glycerin skeleton in the range of 80:20 to 20:80.
If the mass ratio of the acrylic (meth)acrylate to the acrylate having a glycerin skeleton is in the range of 80:20 to 20:80, it can have impact resistance, scratch resistance, and stain resistance, and a mass ratio in the range of 60:40 to 40:60 is more preferable.

Furthermore, it is more preferable that the active energy ray curable coating agent of the present invention contains 1 to 10% by mass of a cellulose-based resin having a number average molecular weight of 10,000 to 80,000, relative to the total mass of the active energy ray curable coating agent.
By including 1 to 10% by mass of cellulose-based resin with a number-average molecular weight of 10,000 to 80,000, impact resistance and stain resistance tend to improve.

(Cellular resin)
Examples of cellulose-based resins include cellulose acetate propionate, cellulose acetate butyrate and other cellulose ester resins, nitrocellulose (also known as nitrated cotton), hydroxyalkylcellulose, and carboxyalkylcellulose. Cellulose ester resins preferably have an alkyl group, and examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, and hexyl groups, and the alkyl group may also have substituents.
Of the above, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred as cellulose-based resins. Furthermore, cellulose acetate propionate and cellulose acetate butyrate are more preferred.
Preferably, the molecular weight is 10,000 to 80,000 in number average molecular weight, and more preferably 20,000 to 40,000. Furthermore, a glass transition temperature of 120°C to 180°C is preferred. The combined use of the acrylic (meth)acrylate and an acrylate having a glycerin skeleton is expected to further improve impact resistance and stain resistance.

The aforementioned cellulose-based resin is preferably contained in an amount of 1 to 10% by mass relative to the total mass of the active energy ray curable coating agent, and can also be used as a biomass raw material.

(Photopolymerization initiator)
The active energy ray curable coating agent of the present invention typically uses a photopolymerization initiator, but this is not the case when a curing method that does not require an initiator such as an electron beam is selected. Any known photopolymerization initiator may be used.

Among these, radical polymerization type photopolymerization initiators are preferred. α-hydroxyalkyl ketone-based photopolymerization initiators are particularly preferred because they do not discolor the solution when dissolving active energy ray-curable compounds and exhibit minimal yellowing over time. Examples of α-hydroxyalkyl ketone-based photopolymerization initiators include 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-(4-i-propylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, and 1-hydroxycyclohexylphenyl ketone. Furthermore, phenylglyoxolate-based photopolymerization initiators are also preferred. Examples of phenylglyoxolate-based photopolymerization initiators include methylbenzoyl formate. Among these, 1-hydroxycyclohexylphenyl ketone is preferred.

Furthermore, as other radical polymerization type photopolymerization initiators, monoacylphosphine oxide-based photopolymerization initiators having absorption wavelengths in the long-wavelength region of ultraviolet light may be used in appropriate combinations. Examples of monoacylphosphine oxide-based photopolymerization initiators include monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,6-dimethoxybenzoyl-diphenylphosphine oxide, 2,6-dichlorobenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-phenylphosphinate methyl ester, 2-methylbenzoyl-diphenylphosphinate isopropyl ester, and pivaloylphenylphosphinate isopropyl ester. Among these, 2,4,6-trimethylbenzoyl-diphenylphosphinate is particularly preferred because it has a UV absorption wavelength that matches the emission wavelength range of UV-LEDs with emission wavelengths of 385 nm and 395 nm, resulting in favorable curability and minimal yellowing of the cured film.

When using the aforementioned photopolymerization initiators, they may be used individually or in combination of two or more. The total amount of photopolymerization initiators added is preferably in the range of 0.01 to 15.0% by mass of the total mass of the active energy ray curable coating agent. A concentration of 0.01% by mass or more provides good curability. Furthermore, a concentration of 15.0% by mass or less ensures that the fluidity of the coating agent is maintained for a long period, guaranteeing good processability and workability.

Furthermore, the curing rate can be accelerated by adding a tertiary amine compound selected from aliphatic amine derivatives and/or benzoic acid amine derivatives as a sensitizer. Tertiary amine compounds are known to enhance reactivity and prevent reaction inhibition by oxygen. Suitable tertiary amine compounds include, for example, free alkylamines such as triethylamine, methyldiethanolamine, and triethanolamine; aromatic amines such as 2-ethylhexyl-4-dimethylaminobenzoate and ethyl-4-dimethylaminobenzoate; and polymerizable unsaturated amines (e.g., (meth)acrylated amines). Active energy ray polymerizable compounds are preferred because they have low odor, low volatility, and the ability to suppress yellowing by being incorporated into the polymer matrix upon curing.

The tertiary amine compound can be used in an amount of preferably 0.1 to 10% by mass, more preferably 0.3 to 3% by mass, of the total mass of the active energy ray curable coating agent.

(Matte agent)
The active energy ray curing coating agent of the present invention may use a matting agent as needed when a matte appearance is required. The matting agent can be any known agent with an average particle size of 1 to 15 μm, and can be used alone or in combination without any particular limitations on whether it is organic or inorganic. Specifically, examples of inorganic particles such as silica, titanium dioxide, alumina particles (aluminum oxide), calcium carbonate, barium sulfate, and glass, or organic particles such as acrylic resin, urethane resin, polycarbonate resin, silicone resin, and polystyrene resin, as well as silicone beads, can be used. As inorganic fine particles that can be expected to have a high matting effect, silica and aluminosilicate beads are preferred, and as organic fine particles, acrylic resin beads, urethane resin beads, and silicone beads are preferred.
The amount of matting agent added is preferably 5 to 20% by mass of the total mass of the active energy ray curing coating agent, and more preferably 5 to 15% by mass. If the content is 5% by mass or more, a sufficient matting effect can be obtained, and if it is 20% by mass or less, the coating agent tends to maintain a viscosity suitable for application and scratch resistance.

(silica)
The silica used in this invention is not particularly limited as long as its average particle size is in the range of 1 to 15 μm; any known silica can be used. In this invention, the average particle size is the value measured by laser diffraction.
Specifically, amorphous silica is more preferred as silica. Examples of amorphous silica include diatomaceous earth and activated clay, and among amorphous silicas, synthetic amorphous silica such as dry silica, wet silica, and silica gel can be used. Among these, wet silica produced by the neutralization and decomposition reaction of an aqueous sodium silicate solution with an acid or alkali metal salt is preferred. Surface-treated wet silica can also be used. There are no particular restrictions on the method of surface-treating the silica particles, and any known method is acceptable. Examples include surface treatment with wax or silane coupling agent. A mixture of surface-treated and untreated wet silica may be used.

The average particle size of the wet-processed silica used as the matting agent is 1 to 15 μm, more preferably 1.5 to 8 μm. If the average particle size is 1 μm or larger, a significant increase in viscosity can be suppressed, resulting in a viscosity suitable for coating. Furthermore, if the average particle size is 15 μm or smaller, a sufficient matte finish can be obtained due to the effect of silica orientation on the surface of the coating film.

When silica is used, its content is preferably 5 to 20% by mass of the total mass of the active energy ray curable coating agent, and more preferably 5 to 15% by mass. A content of 5% by mass or more provides sufficient matte effect, while a content of 20% by mass or less tends to maintain the viscosity and scratch resistance required for application as a coating agent.

(beads)
The active energy ray curing coating agent of the present invention may further use beads. There are no particular limitations on the beads, and known beads can be used. Specifically, acrylic resin beads, urethane resin beads, silicone beads, glass beads, aluminosilicate beads, etc., can be used. By adding beads to the silica used as a matting agent, it is possible to improve the scratch resistance of the coated surface in addition to achieving a moderate low gloss. Although a larger amount of beads is required than silica as a matting agent, an advantage is that it is easier to fine-tune the gloss level by adjusting the amount of beads added. Among these, acrylic resin beads are preferred.

The active energy ray curable coating agent of the present invention may contain an organic solvent as needed.

(Organic solvents)
Any organic solvent that can dissolve the active energy ray-curable coating agent used can be used.
Examples include aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic hydrocarbons such as n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane; esters such as ethyl acetate, butyl acetate, and propyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and n-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether; and ether esters such as propylene glycol monomethyl ether acetate.

From the viewpoint of coatability, the active energy ray curable coating agent of the present invention is preferably adjusted using an organic solvent or the like to a viscosity suitable for coating in the coating film manufacturing method of the present invention described later. The viscosity is preferably adjusted to 30 to 10,000 mPa·s, and more preferably to 30 to 5,000 mPa·s.

(Other acrylates)
The active energy ray curable coating agent of the present invention may optionally contain, in addition to the acrylic (meth)acrylate, the acrylate having a glycerin skeleton, and the cellulose resin, other known acrylate resins such as urethane (meth)acrylate and epoxy (meth)acrylate, and/or (meth)acrylate monomers/oligomers. In this case, the amount added is preferably 0 to 25% by mass relative to the total mass of the acrylic (meth)acrylate and the acrylate having a glycerin skeleton, within a range that does not impair the physical properties of the acrylic (meth)acrylate and the acrylate having a glycerin skeleton.

(Other resins)
Furthermore, in addition to the acrylic (meth)acrylate, the acrylate having a glycerin skeleton, and the cellulose resin, known binder resins may be used in combination as needed. Examples include vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl isobutyl ether copolymer resins, acrylic resins, rosin resins, polyurethane resins, polyamide resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, polyvinyl chloride resins and other vinyl chloride resins, polyester resins, alkyd resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, petroleum resins, and the like.

(Additives)
Furthermore, the active energy ray curing coating agent of the present invention may optionally contain polymerization inhibitors, leveling agents, thixotropic agents, waxes, drying agents, thickeners, anti-sagging agents, plasticizers, dispersants, anti-settling agents, defoaming agents, ultraviolet absorbers, light stabilizers, and the like.

(Manufacturing of active energy ray curing type coating agent)
The active energy ray curable coating agent of the present invention can be manufactured by mixing and dispersing acrylic (meth)acrylate, acrylate having a glycerin skeleton, cellulose resin, photopolymerization initiator, matting agent, organic solvent, and various other additives.
The active energy ray curable coating agent of the present invention can be adjusted by appropriately adjusting the size of the grinding media in the disperser, the packing rate of the grinding media, the dispersion processing time, etc. As the disperser, commonly used types such as roller mills, ball mills, pebble mills, attritors, and sand mills can be used.
If the coating agent contains air bubbles or unexpectedly large particles, these can degrade the quality of the coated product, so it is preferable to remove them by filtration or other means. Conventional known filters can be used.

(Method for forming a coating film)
The active energy ray curing coating agent of the present invention can form a coating film using known coating and printing methods. Specific examples of coating methods include, for example, a roll coater, gravure coater, gravure offset coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, offset printing press, screen printing press, etc., as appropriate.

The coating film formed by the above method can be obtained by drying the solvent in a drying oven or the like, and then curing it with active energy rays, if the coating agent used contains an organic solvent.

(base material)
The substrate used in this invention is not particularly limited. For example, if it is a decorative sheet for building materials, a general-purpose substrate sheet used for decorative sheets can be used as the substrate.
There are no particular limitations on the base sheet; general decorative sheets, sheets (films) made of general-purpose thermoplastic resins, or paper can be used.
Examples of sheets (films) formed from thermoplastic resins include polyolefin resins such as polyethylene, ethylene-α-olefin copolymer, polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, propylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer saponified, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer; polyvinyl chloride, polyethylene terephthalate (PET), polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, ionomer, acrylic acid ester polymer, and methacrylic acid ester polymer. The base sheet may be formed by using these resins individually or in combination of two or more.

The base sheet may be colored, and may contain various additives as needed, such as fillers, matting agents, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, UV absorbers, and light stabilizers. The thickness of the base sheet can be appropriately set depending on the application and method of use of the final product, but generally, 20 to 300 μm is preferred.

One or both sides of the base sheet may be subjected to surface treatments such as corona discharge treatment, ozone treatment, plasma treatment, ionizing radiation treatment, or dichromate treatment, as needed. For example, when performing corona discharge treatment, the surface tension of the base sheet surface should be set to 30 dyne or higher, preferably 40 dyne or higher. Surface treatment should be carried out according to the standard methods for each treatment.

Examples of paper substrates for decorative sheets include tissue paper, regular paper, reinforced paper, resin-impregnated paper, titanium paper, and other types of paper sheets.

Alternatively, wood-based decorative panels commonly used for decorative panels may be used as the base material. Examples of wood-based base materials for wood-based decorative panels include plywood, particleboard, hardboard, and MDF, which have been conventionally used as wood-based base materials for decorative panels, furniture, and building materials. Furthermore, the manufacturing method by which these known base materials were obtained is irrelevant.
Furthermore, examples of non-combustible materials that can be used as base materials include perforated board building materials made from materials such as gypsum board, gypsum board, and calcium silicate board; ceramic sheets such as pottery, porcelain, stoneware, earthenware, glass, and enamel; and metal sheets such as iron sheets, galvanized steel sheets, polyvinyl chloride sol coated steel sheets, aluminum sheets, and copper sheets.

(Step (I))
A coating film is formed on a substrate selected from the above substrates according to the intended use, using one of the above coating methods, with the active energy ray curable coating agent of the present invention.

(Step (II))
Next, the coating film is irradiated with an active energy beam. The active energy beam can be either ultraviolet light or an electron beam.
Ultraviolet irradiation can be carried out by known methods. For example, ultraviolet light can be emitted from light sources such as germicidal lamps, ultraviolet fluorescent lamps, ultraviolet light-emitting diodes (UV-LEDs), carbon arcs, metal halide lamps, xenon lamps, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps for copying, medium-pressure or high-pressure mercury lamps, ultra-high-pressure mercury lamps, electrodeless lamps, metal halide lamps, and natural light.
For the present invention to exert its maximum effect, it is preferable that the cumulative amount of ultraviolet light is in the range of 20 to 1000 mJ/ ^cm² . In particular, it is even more preferable that the cumulative amount is in the range of 40 to 800 mJ/ ^cm² .
If the concentration is 20 mJ/ ^cm² or higher, the curing efficiency is good, and if it is 1000 mJ/ ^cm² or lower, it is possible to prevent damage to the substrate due to heat generation.

On the other hand, when using electron beams, an electron beam irradiation device is used. The irradiation dose is preferably around 10 to 230 kGy, and more preferably around 10 to 100 kGy. In the case of electron beam irradiation, the oxygen concentration in the atmosphere is preferably 2% or less.

The thickness of the coating film obtained in this manner is preferably in the range of 0.1 to 100 μm, and most preferably in the range of 0.5 to 50 μm. This thickness range allows the effects of the present invention to be maximized.

Furthermore, laminates using the active energy ray curing coating agent of the present invention can be widely applied not only to the aforementioned building materials such as decorative sheets, but also to surface coating applications for furniture, car interiors, musical instruments, office supplies, sporting goods, toys, and more.

The present invention will be described in more detail below with reference to examples. In the following examples, "parts" and "parts by mass" refer to mass percentages.

In this invention, the number-average molecular weight or weight-average molecular weight (in polystyrene equivalent) was measured by GPC using the HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation columns: Four TSKgelGMHHR-N columns manufactured by Tosoh Corporation were used.
Column temperature: 40°C.
Mobile layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd.
Flow rate: 1.0ml/min.
Sample concentration: 1.0% by weight.
Sample injection volume: 100 microliters.
Detector: Differential refractometer.
Furthermore, the glass transition temperature (Tg) was measured using a differential scanning calorimeter ("DSC Q100" manufactured by TA Instruments Co., Ltd.) under a nitrogen atmosphere and with a cooling device, scanning was performed within a temperature range of -80 to 450°C and a heating rate of 10°C/min.
Furthermore, the hydroxyl value of each acrylic acrylate resin is calculated by back titrating the remaining acid with an alkali after acetylating the hydroxyl groups in the resin with an excess of acetyl reagent, and expressing the amount of hydroxyl groups per gram of resin in mg of potassium hydroxide (KOH), in accordance with JIS K0070.
Furthermore, the average particle size of silica was measured using the Nanotrac UPA EX-150 nanoparticle size distribution analyzer manufactured by Nikkiso Co., Ltd.

(Preparation of active energy ray curing type coating agent)
[Example 1]
An active energy ray curable coating agent (1) was prepared by stirring and mixing 40 parts by mass of acrylic acrylate A (weight-average molecular weight 25,000, Tg 56℃, hydroxyl value 113 mgKOH/g) with a double bond equivalent of 250 g/mol, 10 parts by mass of glycerin diacrylate "Aronics M-920" (manufactured by Toagosei Co., Ltd.), 10 parts by mass of photopolymerization initiator 1-hydroxycyclohexyl phenyl ketone "Omnirad 184" (manufactured by IGM Corporation), 8 parts by mass of matting agent wet silica "Sylysia 350" (average particle size 3.9 μm, manufactured by Fuji Silysia Chemical Co., Ltd.), 16 parts by mass of methyl ethyl ketone, and 16 parts by mass of ethyl acetate for a total of 100 parts by mass in a stirrer for 1 hour.

[Examples 2-7, Comparative Examples 1-4]
Each active energy ray-curable coating agent was prepared according to the formulations shown in Tables 1 and 2, using the same procedure as in Example 1.
For Comparative Example 3, DPHA (dipentaerythritol hexaacrylate) "Aronics M-402" (manufactured by Toagosei Co., Ltd.) was used as the other monomer, and for Comparative Example 3, PEG400 diacrylate "PEG400DA" (manufactured by Daicel Ornex Co., Ltd.) was used as the other monomer.

<Formation of coating film by process (I)>
Using a polypropylene film (manufactured by Okamoto Co., Ltd.) as the base material, the active energy ray curable coating agents prepared in Examples 1 to 7 and Comparative Examples 1 to 4 were applied to a film thickness of approximately 10 μm using a bar coater (#10).

<Ultraviolet irradiation by process (II)>
Next, using a UV irradiation device (GS Yuasa Corporation) equipped with an air-cooled high-pressure mercury lamp (output 120 W/cm², 1 lamp) and a belt conveyor, the coated object was placed on the conveyor and passed under the lamp (irradiation distance 11 cm) at a speed of 25 meters per minute in open air to cure the coating film.
The amount of ultraviolet radiation was confirmed to be 60 mJ/ ^cm² using an integrated ultraviolet light meter (Industrial UV Checker UVR-N1, manufactured by GS Yuasa Corporation).

[Evaluation Method]
This invention describes an active energy ray curable coating agent and a method for evaluating the resulting laminate.

[Evaluation Item 1: Impact Resistance]
The fully cured coating film surface was evaluated using a DuPont impact deformation test to measure its impact resistance in accordance with JIS K5600-5-3.
The experimental method involved attaching a 6.35 mm radius mold and support stand to a test piece made by bonding a decorative sheet to plywood. A 500 g weight was dropped onto the piece, and the drop height was gradually increased. The minimum height at which cracks appeared in the coating was visually observed in the following three stages. A result of ○ or higher was considered acceptable.
(Evaluation criteria)
◎: 50 cm or more ○: 30 cm or more, but less than 50 cm ×: Less than 30 cm

[Evaluation Item 2: Scratch Resistance]
The surface of the obtained coating film was subjected to a 1.5 kg load of steel wool (BON STAR No. 0000, manufactured by Nippon Steel Wool Co., Ltd.) and moved back and forth. The degree of scratching of the coating film was evaluated using a three-stage criterion. ○ or higher was considered acceptable.
(Evaluation criteria)
◎: No scratches at all, or a slight change in gloss, but no linear scratches. ○: Linear scratches cover less than half of the friction surface. ×: Linear scratches cover almost the entire friction surface, and the paint film turns white.

[Evaluation Item 3: Stain Resistance]
In accordance with the JAS Special Plywood Standard Contamination Test A, contaminants were applied to the surface of the coating film, and after 4 hours, the surface was wiped with an alcohol-containing cloth. The amount of remaining contaminants was then visually observed. The contaminants used were commercially available black marker, red crayon, and blue ink. The contamination level was evaluated according to the following three criteria. A score of ○ or higher is considered acceptable.
(Evaluation criteria)
◎: No residual contaminants at all ○: Some residual contaminants remain, but they are minor and do not pose a practical problem ×: Significant residual contaminants remain

Tables 1 and 2 show the composition of each active energy ray curable coating agent and the evaluation results of the fabricated laminates.
Note that all values in the table are in parts by mass or mass percent. Blank spaces indicate that the ingredient is not included.

The abbreviations used in the table are shown below.
• M-920: Glycerin diacrylate, manufactured by Toagosei Co., Ltd. as "Arronix M-920"
• M-930: Glycerin triacrylate, manufactured by Toagosei Co., Ltd. as "Arronix M-930"
• M-460: Ethylene oxide-modified diglycerin acrylate, manufactured by Toagosei Co., Ltd. as "Aronics M-460"
DPHA: Dipentaerythritol hexaacrylate, manufactured by Toagosei Co., Ltd. as "Arronix M-402"
PEGDA: PEG400 diacrylate, manufactured by Daicel Ornex Co., Ltd.
• CAB-381-01: Cellulose acetate butyrate, manufactured by Eastman Chemical Co., Ltd. • Silysia 350: Matte silica (average particle size 3.9 μm), manufactured by Fuji Silysia Chemical Co., Ltd. • Omnirad 184: Photopolymerization initiator 1-hydroxycyclohexyl phenyl ketone, manufactured by IGM Resins B.V.

In this invention, by using acrylic acrylate in combination with acrylate having a glycerin skeleton, a well-balanced coating film can be obtained that has both high crosslink density and flexibility, and can possess impact resistance, scratch resistance, and stain resistance while using biomass raw materials.
Comparative Example 1, which uses acrylic (meth)acrylate alone, shows that the balance of physical properties is not maintained, resulting in reduced scratch resistance.
Comparative Example 2, which uses an acrylate with a glycerin skeleton alone, shows that the physical properties are unbalanced and impact resistance is reduced.
Comparative Example 3, which uses a polyfunctional acrylate with a dipentaerythritol skeleton, shows a decrease in impact resistance due to insufficient flexibility.
Comparative Example 4, using PEGDA:PEG400 diacrylate, did not achieve sufficient hardness, demonstrating reduced scratch resistance and stain resistance.

Claims (4)

An active energy ray curable coating agent containing acrylic (meth)acrylate and acrylate having a glycerin skeleton,
The mass ratio of the acrylic (meth)acrylate to the acrylate having a glycerin skeleton is in the range of 80:20 to 20:80.
The acrylic (meth)acrylate has a double bond equivalent of 200 to 750 g/mol, a weight-average molecular weight of 10,000 to 100,000, and a hydroxyl value of 5 to 300 mgKOH/g.
The acrylate having the glycerol skeleton is a compound having 2 to 4 (meth)acryloyl groups.
A coating agent characterized by its ability to be cured by activated energy rays. Furthermore, the active energy ray curable coating agent according to claim 1 contains 1 to 10% by mass of a cellulose-based resin having a number average molecular weight of 10,000 to 80,000, relative to the total mass of the active energy ray curable coating agent. The active energy ray curable coating agent according to claim 1, wherein the photopolymerization initiator is contained in an amount of 0.01 to 15.0% by mass of the total mass of the active energy ray curable coating agent. A method for manufacturing a laminate, comprising the steps of (I) forming a coating film of an active energy ray-curable coating agent on a substrate, and (II) irradiating the coating film with active energy rays, wherein the active energy ray-curable coating agent is the active energy ray-curable coating agent described in any one of claims 1 to 3 .