JP7464411B2 - Active energy ray curable building material paint and decorative sheet obtained - Google Patents

Description

The present invention relates to an active energy ray-curable building material coating that is not deteriorated by ultraviolet rays and has excellent ultraviolet curing properties and weather resistance, and a decorative sheet using the active energy ray-curable building material coating.

Decorative sheets have been widely used for furniture and flooring materials inside buildings such as houses, and their surfaces are painted with various coatings for the purpose of protection and beautification. Decorative sheets are a general term for printed materials that are attached to wood and other materials to decorate the surface.
In the field of building interior materials, decorative sheets are increasingly being replaced by painted finishes for everything from furniture, walls, ceilings and floors, due to their high design quality, ease of processing, and economical advantages such as low cost and ability to be produced in small lots.
Furthermore, in recent years, weather resistance has become a requirement in the interior design field to prevent deterioration caused by sunlight, especially ultraviolet rays, that shines through windows. In addition, there is also a growing demand for the development of highly weather-resistant decorative sheets that can be used not only in interior design applications but also in exterior applications.

Conventionally, organic triazine ultraviolet absorbers (UVAs) and hindered amine light stabilizers (HALS) have been used as additives in printing inks used for building material coatings to impart weather resistance (e.g., References 1 and 2).
The organic triazine ultraviolet absorber (UVA) is an additive that absorbs ultraviolet light and converts it into heat energy to protect the coating film, and the hindered amine light stabilizer (HALS) is an additive that captures radicals generated by ultraviolet light to prevent deterioration of resins and coating films, and by changing the type and content of these additives, it is possible to efficiently prevent deterioration caused by ultraviolet light.
However, when an active energy ray-curable resin is used as a building material coating, the ultraviolet ray absorber absorbs ultraviolet rays, which may cause curing inhibition.

JP 2018-203866 A JP 2012-136647 A

The objective of the present invention is to provide an active energy ray-curable building material coating that is not deteriorated by ultraviolet rays and has excellent ultraviolet curing properties and weather resistance, and a decorative sheet using the active energy ray-curable building material coating.

That is, the present invention relates to an active energy ray-curable building material coating material that is characterized by containing an acrylic resin containing a (meth)acryloyl group with a double bond equivalent of 100 to 750 g/mol, and a metal oxide.

The present invention also relates to an active energy ray-curable building material coating material in which the weight average molecular weight of the acrylic resin containing the (meth)acryloyl group is 10,000 to 100,000.

The present invention also relates to an active energy ray-curable building material coating material in which the glass transition temperature (Tg) of the acrylic resin containing the (meth)acryloyl group is in the range of 40 to 130°C and the hydroxyl value is 5 to 300 mgKOH/g.

The present invention also relates to an active energy ray-curable building material coating material in which the metal oxide is zinc oxide having an average particle size of 0.5 to 500 nm.

The present invention also relates to an active energy ray-curable building material coating material in which the zinc oxide content is 1 to 50 mass % of the total solid content of the active energy ray-curable building material coating material.

The present invention also relates to an active energy ray-curable building material coating material that contains an acrylic (meth)oligomer and/or a urethane (meth)acrylate resin.

The present invention also relates to a decorative sheet using this active energy ray-curable building material paint.

The present invention also relates to a method for producing a coated building material having an active energy ray-curable coating on a building material substrate, the method comprising the steps of applying the active energy ray-curable building material coating to the building material substrate and irradiating the substrate with active energy rays.

The active energy ray-curable building material paint of the present invention is not deteriorated by ultraviolet rays and has excellent ultraviolet curing properties and weather resistance, so it is possible to provide a decorative sheet using this active energy ray-curable building material paint.

The active energy ray-curable building material coating of the present invention is characterized by containing an acrylic resin containing a (meth)acryloyl group with a double bond equivalent of 100 to 750 g/mol, and a metal oxide.

The (meth)acryloyl group-containing acrylic resin used in the present invention is not particularly limited, and any acrylic resin obtained by a known method can be used.
Specifically, for example, a method of blending and copolymerizing a carboxyl group-containing polymerizable monomer such as acrylic acid or methacrylic acid as the copolymerization component to obtain the copolymer having a carboxyl group or an amino group, and then reacting the carboxyl group or the amino group with a monomer having a glycidyl group and a (meth)acryloyl group such as glycidyl methacrylate; a method of blending and copolymerizing a hydroxyl group-containing monomer such as 2-hydroxyethyl methacrylate or 2-hydroxyethyl acrylate as the copolymerization component to obtain the copolymer having a hydroxyl group, and then reacting the hydroxyl group with a monomer having an isocyanate group and a (meth)acryloyl group such as isocyanate ethyl methacrylate; a method in which a glycidyl group-containing polymerizable monomer such as glycidyl methacrylate is blended as the copolymerization component in advance, copolymerized to obtain the copolymer having a glycidyl group, and then the glycidyl group is reacted with a carboxyl group-containing polymerizable monomer such as acrylic acid or methacrylic acid; a method in which a carboxyl group is introduced to the copolymer terminal using thioglycolic acid as a chain transfer agent during polymerization, and a monomer having a glycidyl group and a (meth)acryloyl group, such as glycidyl methacrylate, is reacted with the carboxyl group; and a method in which a carboxyl group-containing azo initiator such as azobiscyanopentanoic acid is used as a polymerization initiator to introduce a carboxyl group into the copolymer, and a monomer having a glycidyl group and a (meth)acryloyl group, such as glycidyl methacrylate, is reacted with the carboxyl group.

Among these, the simplest and most preferred method is to copolymerize a carboxyl group-containing monomer such as acrylic acid or methacrylic acid, or an amino group-containing monomer such as dimethylaminoethyl methacrylate or dimethylaminopropylacrylamide, and then react the carboxyl group or amino group with a monomer having a glycidyl group and a (meth)acryloyl group, such as glycidyl methacrylate, or to previously blend and copolymerize a glycidyl group-containing polymerizable monomer such as glycidyl methacrylate as the copolymerization component to obtain the copolymer having a glycidyl group, and then react the glycidyl group with a carboxyl group-containing polymerizable monomer such as acrylic acid or methacrylic acid.

The monomer components constituting the acrylic resin containing a (meth)acryloyl group used in the present invention include monofunctional monomers such as ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone, as well as polyfunctional monomers such as trimethylolpropane (meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol (meth)acrylate.

The double bond equivalent of the acrylic resin containing the (meth)acryloyl group must be in the range of 100 to 750 g/mol. If the double bond equivalent of the acrylic resin containing the (meth)acryloyl group is less than 100 g/mol, the volume shrinkage during curing is large, and cracks may occur due to curvature or distortion of the coating film, and the processability tends to decrease due to dense crosslinking. If it exceeds 750 g/mol, there is a tendency for the reactive groups to be insufficient, resulting in insufficient physical properties such as hardness after the reaction. It is more preferable that the double bond equivalent is in the range of 200 to 400 g/mol, and even more preferable that it is in the range of 200 to 300 g/mol.
The double bond equivalent of the acrylic resin containing a (meth)acryloyl group is defined by the following formula.
"Double bond equivalent" = "Molecular weight of one molecule of acrylic resin containing (meth)acryloyl group" / "Number of double bonds"

The weight average molecular weight of the acrylic resin containing the (meth)acryloyl group is preferably in the range of 10,000 to 100,000. If the weight average molecular weight of the acrylic resin containing the (meth)acryloyl group is 10,000 or more, tackiness is unlikely to remain in the coating film, and it is easy to make the coating film tack-free only by the drying process, and if it is 100,000 or less, the viscosity of the active energy ray curable building material coating material does not become too high, and the problem of excessive dilution during coating, in which a sufficient coating amount cannot be obtained, can be avoided. From the viewpoint of workability, it is more preferable that it is 10,000 to 50,000, and even more preferable that it is in the range of 10,000 to 30,000.
The weight average molecular weight is determined by measurement using GPC in terms of polystyrene.

Furthermore, the glass transition temperature (Tg) of the acrylic resin containing the (meth)acryloyl group is preferably in the range of 40 to 130° C., and if it is 40° C. or higher, sufficient strength can be obtained after curing when formed into a coating film, and if it is 130° C. or lower, the tendency that brittleness appears and processability decreases when formed into a coating film can be suppressed. The hydroxyl value of the acrylic resin containing the (meth)acryloyl group is preferably in the range of 5 to 300 mgKOH/g, and if it is 5 mgKOH/g or higher, low gloss tends to be easily maintained without decreasing dispersion when, for example, a matting agent such as wet silica is used in combination, and if it is 300 mgKOH/g or lower, the tendency that contamination resistance decreases can be suppressed.
The glass transition temperature (Tg) was measured by using a differential scanning calorimeter and scanning with a cooling device in a nitrogen atmosphere at a temperature range of −80 to 450° C. with a temperature rise rate of 10° C./min.

The content of the acrylic resin containing the (meth)acryloyl group is preferably 20 to 85% by mass of the total solid content in the active energy ray-curable building material coating material from the viewpoint of favorable coating properties and curing properties of the coating surface, and more preferably in the range of 25 to 80% by mass.

Next, the metal oxide used in the active energy ray-curable building material coating of the present invention will be described. Examples of the metal oxide include molybdenum oxide, tungsten oxide, titanium oxide, zirconium oxide, tin oxide, copper oxide, zinc oxide, aluminum oxide, nickel oxide, iron oxide, manganese oxide, antimony trioxide, antimony tetroxide, and antimony pentoxide. Of these, zinc oxide is preferred.

Furthermore, the average particle size of zinc oxide used in the active energy ray-curable building material coating material of the present invention is preferably 0.5 to 500 nm, more preferably 1 to 200 nm, and most preferably 10 to 100 nm. Compared with zinc oxide with an untreated surface, zinc oxide that has been "hydrogen dimethicone-treated" can reduce radical attack on the organic coating film by preventing radicals generated after absorbing ultraviolet rays from being released outside the surface treatment layer, and weather resistance tends to be improved.
When zinc oxide is treated with hydrogen dimethicone, it can be roughly divided into two types: untreated zinc oxide is directly treated with hydrogen dimethicone, and zinc oxide particle surface is coated with high density silica layer for the purpose of particle inactivation, particle surface is once covered with high density silica, and then further treated with hydrogen dimethicone.As the zinc oxide used in the active energy ray curable building material coating material of the present invention, the former type of untreated zinc oxide is directly treated with hydrogen dimethicone, which is more preferable.The reason for this is that in the latter method of covering zinc oxide particle surface with high density silica layer to inactivate and weaken the cohesive force of zinc oxide, the high density silica layer is hydrous silica, which hinders the hydrophobicity desired in the active energy ray curable building material coating material of the present invention, and tends to reduce the high dispersibility with the resin component or solvent that is mixed.
Furthermore, when the untreated zinc oxide described above is directly treated with hydrogen dimethicone, the zinc oxide particle surface is uniformly and completely covered with silicone, and the active surface is not exposed even when the particles are crushed in a wet treatment, so that a part of the zinc oxide particle surface is exposed, and the active surface is exposed in a dry treatment, which results in improved dispersibility of the active energy ray-curable building material coating material. This is more preferable than a wet treatment in which the surface of the zinc oxide particles is uniformly and completely covered with silicone, and the active surface is not exposed even when the particles are crushed.

Examples of the siloxane compound used in the hydrogen dimethicone treatment applied to the zinc oxide used in the active energy ray curable building material coating material of the present invention include various silicone oils such as methyl polysiloxane, methylphenyl polysiloxane, methyl hydrogen polysiloxane, methyl cyclo polysiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, dodecamethyl cyclohexasiloxane, octamethyl trisiloxane, tetradecamethyl hexasiloxane, dimethyl siloxane-methyl (polyoxyethylene) siloxane-methyl (polyoxypropylene) siloxane copolymer, dimethyl siloxane-methyl (polyoxyethylene) siloxane copolymer, dimethyl siloxane-methyl (polyoxypropylene) siloxane copolymer, dimethyl siloxane-methyl cetyloxy siloxane copolymer, and dimethyl siloxane-methyl stearoxy siloxane copolymer. Among them, methyl hydrogen polysiloxane and methyl polysiloxane are preferred.
The amount of zinc oxide used in the active energy ray-curable building material coating material of the present invention is preferably in the range of 1 to 60 mass % of the total solids of the coating material, more preferably in the range of 10 to 55 mass %, and even more preferably in the range of 20 to 50 mass %.

In addition, the active energy ray curable building material coating material of the present invention may further contain an acrylic (meth) oligomer and/or a urethane (meth) acrylate resin in order to improve the scratch resistance of the coating surface. The composition ratio when adding these acrylic (meth) oligomers and/or urethane (meth) acrylate resins is preferably 50 to 99% by mass of acrylic (meth) acrylate resin and 1 to 50% by mass of acrylic (meth) oligomer and/or urethane (meth) acrylate resin, in terms of the "mass ratio range of the solid contents of the three" when acrylic (meth) acrylate/acrylic (meth) oligomer/urethane (meth) acrylate are used in combination. More preferably, it is 60 to 90% by mass of acrylic (meth) acrylate resin and 10 to 40% by mass of acrylic (meth) oligomer and/or urethane (meth) acrylate resin. If the blending amount of acrylic (meth)oligomer and/or urethane (meth)acrylate resin exceeds 50% by mass, the coating film becomes viscous and does not become tack-free through the drying process alone.

Examples of the acrylic (meth)oligomer include trimethylolpropane (meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol (meth)acrylate.

Examples of components constituting the urethane (meth)acrylate resin include polyfunctional alcohol components, compounds having one or more alcoholic hydroxyl groups and one or more (meth)acrylic acid esters or (meth)acrylamides in the molecule, and polyisocyanate compounds.
As the polyfunctional alcohol component constituting the urethane (meth)acrylate resin, one or more compounds selected from the compounds exemplified below can be used alone, or two or more compounds can be mixed in any ratio as necessary.

Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, di(1,2-propylene glycol), tri(1,2-propylene glycol), 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 1,5-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,6-hexanediol, 1,2-hexanediol , 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,2-bis(hydroxymethyl)cyclohexane, 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, bis(hydroxymethyl)tricyclodecane, 1,3-bis(hydroxymethyl)adamantane, 2,3-bis(hydroxymethyl)norbornane, 2,5-bis(hydroxymethyl)norbornane, 2,6-bis(hydroxymethyl)norbornane, hydrogenated bisphenol A, hydrogenated bisphenol A ethylene oxide adduct, bisphenol A ethylene oxide adduct, Neopentyl glycol monohydroxypivalate, spiroglycol (3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxospiro[5.5]undecane), trimethylolethane, trimethylolpropane, ethylene oxide modified trimethylolpropane, tris(hydroxyethyl)isocyanuric acid, glycerin, ethylene oxide modified glycerin, propylene oxide modified glycerin, pentaerythritol, ethylene oxide modified pentaerythritol, propylene oxide modified pentaerythritol, ditrimethylolpropane, ethylene oxide modified ditrimethylolpropane, propylene oxide modified ditrimethylolpropane, dipentaerythritol, ethylene oxide modified dipentaerythritol, propylene oxide modified dipentaerythritol, refined castor oil, etc.

Examples of compounds that are components of urethane (meth)acrylate resins and that impart a terminal radically polymerizable unsaturated bond include compounds having one or more alcoholic hydroxyl groups and one or more (meth)acrylic acid esters or (meth)acrylamides in the molecule, as shown below.
Examples of (meth)acrylic acid esters or (meth)acrylamides having one alcoholic hydroxyl group in the molecule include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxymethylcyclohexylmethyl (meth)acrylate, α-hydroxymethyl methyl acrylate, α-hydroxymethyl ethyl acrylate, ε-caprolactone-modified 2-hydroxyethyl (meth)acrylate, γ-butyrolactone-modified 2-hydroxyethyl (meth)acrylate, poly Examples of the (meth)acrylic acid esters having two or more alcoholic hydroxyl groups include (ethylene glycol) mono(meth)acrylate, poly(propylene glycol) mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, glycerin (meth)acrylate stearate, glycerin (meth)acrylate oleate, glycerin di(meth)acrylate, glycerin acrylate methacrylate, bis[(meth)acryloyloxyethyl]isocyanuric acid, and N-(2-hydroxyethyl)(meth)acrylamide.
A mixture of more than one type may be used.
Examples of (meth)acrylic acid esters having two or more alcoholic hydroxyl groups include glycerin (meth)acrylate, trimethylolpropane (meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, dipentaerythritol tetra(meth)acrylate, (meth)acryloyloxyethyl bis(hydroxyethyl)isocyanuric acid, etc. In addition, a compound group generally called epoxy acrylate, which is obtained by reacting an aliphatic diglycidyl ether such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, poly(ethylene glycol) diglycidyl ether, or poly(propylene glycol) diglycidyl ether with (meth)acrylic acid, can be used. One or more compounds selected from these can be used as a compound having a 2-hydroxyl(meth)acrylic acid ester structure at both ends to introduce a radically polymerizable unsaturated bond into the urethane resin skeleton.

As the curing agent used in the active energy ray curable building material coating of the present invention, a publicly known photopolymerization initiator can be used, among which a radical polymerization type photopolymerization initiator is preferred, and an α-hydroxyalkyl ketone-based photopolymerization initiator that does not color the solution when the active energy ray curable compound is dissolved and does not yellow over time is included. 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, 1-hydroxycyclohexyl phenyl ketone, etc. Furthermore, a phenylglyoxolate-based photopolymerization initiator is also preferred. Examples of phenylglyoxolate-based photopolymerization initiators include methylbenzoyl formate, etc. Among them, 1-hydroxycyclohexyl phenyl ketone is preferred.

In addition, other radical polymerization type photopolymerization initiators may be used in appropriate combination with monoacylphosphine oxide photopolymerization initiators that have an absorption wavelength in the long wavelength region of ultraviolet light. Monoacylphosphine oxide 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-phenylphosphine acid methyl ester, 2-methylbenzoyl-diphenylphosphine oxide, and pivaloylphenylphosphine acid isopropyl ester, excluding bisacylphosphine oxides that become colored when dissolved in an active energy ray curable compound. Among these, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is particularly preferable because it has a UV absorption wavelength that matches the emission wavelength range of UV-LEDs that have an emission wavelength of 385 nm or 395 nm, thereby obtaining suitable curability and causing less yellowing of the cured film.

The above-mentioned photopolymerization initiators may be used alone or in combination of two or more. The total content of the photopolymerization initiators in the paint is preferably in the range of 0.1 to 10% by mass based on the total amount of the paint including the organic solvent. If the amount added is less than 0.1% by mass, it is difficult to obtain good curing properties, and if the amount added is more than 10% by mass, the amount of initiator becomes excessive, impairing the fluidity of the paint and reducing processability and workability, which is not preferable.

Furthermore, the curing speed can be increased 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 increase reactivity and prevent reaction inhibition by oxygen. Suitable tertiary amine compounds include free alkylamines such as triethylamine, methyldiethanolamine, and triethanolamine, aromatic amines such as 2-ethylhexyl-4-dimethylaminobenzoate and ethyl-4-dimethylaminobenzoate, and active energy ray polymerizable compounds such as polyunsaturated amines (e.g., (meth)acrylated amines), which are considered to be preferred due to their low odor, low volatility, and ability to be incorporated into the polymer matrix by curing, thereby suppressing yellowing.

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, based on the total amount of the paint including the organic solvent.

Additional optional ingredients include silica for matte finish and scratch resistance, wax, plasticizers, dispersants, and defoamers.

The organic solvents used in the active energy ray-curable building material coating of the present invention include aromatic hydrocarbons such as toluene and xylene, aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane, esters such as ethyl acetate, butyl acetate, and propyl acetate, alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, and alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether.

(Production of active energy ray curable building paint)
The active energy ray-curable building material coating material of the present invention can be produced by previously combining an acrylic resin containing a (meth)acryloyl group and a metal oxide such as zinc oxide, and then dissolving and/or dispersing a photopolymerization initiator, a resin such as an acrylic (meth)oligomer as necessary, and various other additives in an organic solvent.

The active energy ray-curable building material coating material of the present invention can be prepared by appropriately adjusting the size of the grinding media of the dispersing machine, the packing rate of the grinding media, the dispersion treatment time, etc. As the dispersing machine, for example, a commonly used roller mill, ball mill, pebble mill, attritor, sand mill, etc. can be used.
When air bubbles or unexpectedly large particles are contained in the coating material, they degrade the quality of the coating product, so it is preferable to remove them by filtration, etc. As the filter, a conventionally known filter can be used.

Substrates on which the active energy ray-curable building material coating of the present invention can be used include paper and various films for decorative sheets, as well as wood and non-flammable materials.

The decorative sheet is constructed by forming a pattern layer by printing or applying a known printing ink or paint, such as an acrylic, cellulose, vinyl, chlorinated polyolefin, chlorinated rubber, or urethane ink, onto a substrate such as paper or film, and then providing a topcoat layer to cover the pattern layer. The active energy ray-curable building material paint of the present invention forms the topcoat layer.
Examples of the substrate for the decorative sheet include paper sheets such as thin paper, plain paper, reinforced paper, and resin-impregnated paper; titanium paper; polyethylene terephthalate sheets, glycol-modified polyethylene terephthalate sheets (PETG sheets), polyvinyl chloride sheets, polyethylene sheets, acrylonitrile butadiene styrene sheets, and polypropylene sheets; and composite sheets thereof.
Examples of the wood substrate for the wood decorative board include known materials such as plywood, particle board, hardboard, and MDF that have been conventionally used as wood substrates for decorative boards, furniture, building materials, etc. Furthermore, it does not matter by what method these known substrates are obtained.

Furthermore, examples of non-combustible materials that can be used as the base material include perforated board building materials made from gypsum board, gypsum board, calcium silicate board, etc.

Taking the decorative sheet using the active energy ray curable building material paint of the present invention as an example, a design layer is formed by printing or applying a known printing ink or paint, such as an acrylic, cellulose, vinyl, chlorinated polyolefin, chlorinated rubber, or urethane ink, onto the substrate, and then an active energy ray curable building material paint characterized by containing an acrylic resin containing a (meth)acryloyl group with a double bond equivalent of 100 to 750 g/mol, and a metal oxide is applied, and a coated building material is produced through step (I) of first forming a coating film of the building material paint.

Specific examples of coating and printing methods for producing the coating film of the active energy ray-curable building material coating material include coating methods that can be appropriately adopted, such as a roll coater, gravure 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 machine, screen printing machine, etc.

Next, a step (II) is carried out in which the coating film obtained in the step (I) is irradiated at least once with active energy rays of 30 to 1000 mJ/ ^cm2 , thereby making it possible to provide a coated building material having excellent curability and weather resistance of the surface of the coated building material.
Furthermore, if active energy rays can be irradiated in a gas atmosphere with an oxygen concentration of less than 8% by injecting into the reaction vessel one or a mixed gas of two or more kinds selected from nitrogen gas, carbon dioxide gas, and argon gas together with air or alone, the curing of the coating film obtained in the above step (I) can be promoted more efficiently.

The active energy ray in the step (II) of irradiating at least once with 30 to 1000 mJ/ ^cm2 is an ionizing radiation or electromagnetic wave such as ultraviolet ray, electron beam, or gamma ray, and among these, ultraviolet ray or electron beam is preferred.

When irradiating with ultraviolet light in a gas atmosphere with an oxygen concentration of less than 8%, a known ultraviolet light irradiation device equipped with a high-pressure mercury lamp, an excimer lamp, a metal halide lamp, etc. When the amount of ultraviolet light during curing is 80 mJ/ ^cm2 or more, the curing efficiency is good, and when it is 1000 mJ/ ^cm2 or less, it is preferable from the viewpoint of preventing damage to the substrate due to heat.

The active energy ray-curable building material coating material of the present invention can be applied to a substrate and then irradiated with active energy rays to form a cured coating. The active energy rays include ionizing radiation such as ultraviolet rays, electron beams, α rays, β rays, and γ rays, and specific energy sources or curing devices include, for example, 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, ultraviolet rays using natural light as a light source, or electron beams from a scanning type or curtain type electron beam accelerator.
In the active energy ray curable building material coating material of the present invention, as described above, by irradiating with active energy rays, preferably ultraviolet light, etc., the curing reaction can be carried out without leaving a sticky feeling on the finished product even if the coating material is not a two-component curing type. For example, the curing reaction can be carried out using commercially available lamps such as H lamps, D lamps, and V lamps manufactured by Fusion Systems.

When curing in an inert gas, there is little inhibition of curing by oxygen, and the reaction of the radically polymerizable double bonds of the base material, such as the acrylic resin containing the (meth)acryloyl group described above, proceeds more rapidly, curing is sufficiently carried out, and the coating surface of the decorative sheet becomes more resistant because it remains on the surface for a long time even after the passage of time, and adhesion and weather resistance can be further improved. Additive components that are sufficiently fixed are unlikely to come off even when they come into contact with the back surface of the original roll when being wound up on a roll in gravure printing, for example.

The active energy ray-curable building material coating of the present invention can be used not only for building materials, but also for a wide range of surface coating applications, including furniture, musical instruments, office supplies, sporting goods, toys, etc.

The present invention will be described in more detail below with reference to examples. In the examples, "parts" and "parts by mass" refer to mass %.
In the present invention, the weight average molecular weight (converted into polystyrene) was measured by GPC using an HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation column: Four columns of TSKgel GMHHR-N manufactured by Tosoh Corporation were used. Column temperature: 40° C. Mobile phase: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml/min. Sample concentration: 1.0 wt %. Sample injection amount: 100 microliters. Detector: differential refractometer.
The glass transition temperature (Tg) was measured using a differential scanning calorimeter ("DSC Q100" manufactured by TA Instruments Co., Ltd.) by scanning in a nitrogen atmosphere using a cooling device at a temperature range of -80 to 450°C and a temperature rise rate of 10°C/min.
The hydroxyl value of an acrylic resin containing a (meth)acryloyl group is the amount of hydroxyl groups in 1 g of resin calculated by back titrating the remaining acid with an alkali when the hydroxyl groups in the resin are acetylated with an excess of an acetyl reagent, expressed in mg of potassium hydroxide (KOH), and is in accordance with JIS K0070.
The average particle size of zinc oxide was measured using a nanoparticle size distribution analyzer Nanotrac UPA EX-150 manufactured by Nikkiso Co., Ltd.

(Adjustment of building material paint)
[Preparation Example 1]
(Meth) 38.2 parts of acrylic acrylate resin A (double bond equivalent 250 g / mol product, weight average molecular weight 25,000, Tg 56 ° C., hydroxyl value 113 mg KOH / g) as an acrylic resin containing an acryloyl group, 8 parts of 1-hydroxy-cyclohexyl-phenyl-ketone "Omnirad 184" manufactured by BASF, 20 parts of FINEX-52W-LP2 manufactured by Sakai Chemical Industry Co., Ltd. (zinc oxide in which untreated zinc oxide (average particle size 20 nm) is coated with a high density silica layer and treated with hydrogen dimethicone, the mass ratio of the high density silica layer is 10% of the total amount, and the mass ratio of the hydrogen dimethicone layer is 4% of the total amount) and 33.8 parts of ethyl acetate were added, stirred and mixed with a stirrer for 1 hour, and then stirred and treated with a bead mill for 2 hours to prepare building material coating 1.

[Preparation Example 2]
Building material coating material 2 was prepared by mixing and stirring in the same manner as in Preparation Example 1 with the same composition and procedure as in Preparation Example 1, except that acrylic acrylate resin B (double bond equivalent 360 g/mol, weight average molecular weight 25,000, Tg 73°C, hydroxyl value 78 mgKOH/g) was used instead of acrylic acrylate resin A (double bond equivalent 250 g/mol) in Preparation Example 1.

[Preparation Example 3]
Building material coating 3 was prepared by mixing and stirring in the same manner as in Preparation Example 1 with the same composition and procedure as in Preparation Example 1, except that acrylic acrylate resin C (double bond equivalent 550 g/mol, weight average molecular weight 25,000, Tg 85°C, hydroxyl value 50 mgKOH/g) was used instead of acrylic acrylate resin A (double bond equivalent 250 g/mol) in Preparation Example 1.

[Preparation Examples 4 and 5]
The amount of FINEX-52W-LP2 in Preparation Example 3 (zinc oxide in which untreated zinc oxide (average particle size 20 nm) is both coated with a high-density silica layer and treated with hydrogen dimethicone, with the mass ratio of the high-density silica layer being 10% of the total, and the mass ratio of the hydrogen dimethicone layer being 4% of the total) was changed according to Table 1, and the total amount of the paint was adjusted to 100 parts with ethyl acetate. Building material paints 4 and 5 were prepared by mixing and stirring in the same manner.

[Preparation Examples 6 to 8]
According to Table 1, building material coatings 6 to 8 were prepared in the same manner as in Preparation Examples 1 to 3, except that 20 parts of surface-untreated zinc oxide MA-500 (average particle size 25 nm, manufactured by Teika Co., Ltd.) was used instead of FINEX-52W-LP2 in Preparation Examples 1 to 3, and the same formulations and mixing and stirring procedures were used to prepare building material coatings 6 to 8.

[Preparation Example 9]
To 31.2 parts of the acrylic acrylate resin C (double bond equivalent 550 g/mol product, weight average molecular weight 25,000, Tg 85 ° C., hydroxyl value 50 mg KOH/g) of Preparation Example 3, 7 parts of "Aronix M-402 (a mixture of dipentaerythritol pentaacrylate, which is a pentafunctional polymerizable acrylate monomer, and hexaacrylate, which is a hexafunctional polymerizable acrylate monomer, the proportion of pentaacrylate in the product is 30 to 40% by mass%)" manufactured by Toagosei Co., Ltd. was added as another (meth)acrylate. The mixture was mixed and stirred in the same manner as in Preparation Example 3 to prepare building material coating 9.

[Preparation Example 10]
Building material coating material 10 was produced by mixing and stirring in the same manner as in Preparation Example 9 with the same formulation as in Preparation Example 9, except that 7 parts of aliphatic urethane acrylate Miramer PU610 (functionality 6, weight average molecular weight 1800) manufactured by Toyo Chemicals Co., Ltd. was added instead of Aronix M-402 manufactured by Toagosei Co., Ltd. in Preparation Example 9.

[Preparation Example 11]
Instead of FINEX-52W-LP2 in Preparation Example 3, 20 parts of FINEX-50W manufactured by Sakai Chemical Industry Co., Ltd. (zinc oxide obtained by subjecting untreated zinc oxide (average particle size 20 nm) to only hydrogen dimethicone treatment, with the mass ratio of the hydrogen dimethicone treatment layer being 4% of the total) was added, and the same formulation and mixing and stirring were carried out in the same manner as in Preparation Example 3 to prepare building material coating material 11.

[Preparation Example 12]
Instead of the FINEX-52W-LP2 in Preparation Example 3, 20 parts of FINEX-50W manufactured by Sakai Chemical Industry Co., Ltd. (zinc oxide obtained by coating only a high-density silica layer on untreated zinc oxide (average particle size 20 nm), with the mass ratio of the treated layer being approximately 21% of the total) was added, and the same formulation and mixing and stirring were carried out in the same manner as in Preparation Example 3 to produce building material coating material 12.

[Preparation Example 13]
Building material coating material 13 was prepared by mixing and stirring in the same manner as in Preparation Example 3 with the same composition as in Preparation Example 3, except that 20 parts of FINEX-50 manufactured by Sakai Chemical Industry Co., Ltd. (untreated zinc oxide (average particle size 20 nm) that has not been coated with a high-density silica layer or treated with hydrogen dimethicone) was added instead of FINEX-52W-LP2 in Preparation Example 3.

[Preparation Examples 14 to 21]
Building material coatings 14 to 21 were prepared by mixing and stirring the ingredients in the same manner as described in Table 2, except that no zinc oxide was added and 8 parts of an ultraviolet absorber, Tinuvin 400 (manufactured by BASF Japan Ltd.), was added uniformly.

<Preparation of decorative sheet>
[Examples 1 to 13 and Comparative Examples 1 to 8]
An easily adhesive treated polyethylene terephthalate film (hereinafter, PET film, Toyobo Co., Ltd. A4300, thickness 100 μm) was prepared as a substrate, and the building material coating materials prepared in Preparation Examples 1 to 21 were applied using a bar coater (4 μm), and then irradiated once with ultraviolet light from a high-pressure mercury lamp to cure the coating film. Using a UV irradiation device (GS Yuasa Corporation) equipped with an air-cooled high-pressure mercury lamp (output 120 W/cm per lamp) and a belt conveyor, the coating material was placed on the conveyor and passed directly under the lamp (irradiation distance 11 cm) at a speed of 25 meters per minute to cure the building material coating material.
The ultraviolet ray exposure was confirmed to be 40 mJ/ ^cm2 using an ultraviolet ray integrating light meter (GS Yuasa Corporation, Industrial UV Checker UVR-N1).

〔Evaluation methods〕
The method for evaluating the active energy ray-curable building material coating material of the present invention will be described below.

[Evaluation item 1: UV curability]
The surface of the coating film immediately after the preparation of the decorative sheet was touched, and the degree of stickiness of the surface was sensorily evaluated on the following four-level scale.
(Evaluation criteria)
4: Not sticky at all, completely dry.
3: Slight stickiness is felt, but not to the point of causing any problems.
2: Stickiness is present which causes problems in use.
1: Significantly sticky and not completely dry.

[Evaluation item 2: Weather resistance]
The weather resistance of the prepared decorative sheet was visually evaluated using a weather resistance tester (Super UV) in the following four stages. For the test, a Super UV weather resistance accelerated tester (Eye Super UV Tester SUV-W261, manufactured by Iwasaki Electric) was used to irradiate ultraviolet rays with the following settings: illuminance 60 mW, irradiation temperature 63°C, rest temperature 50°C, irradiation humidity 50%, rest humidity 50%, irradiation time 20 hours, condensation time 4 hours, rest time 6 minutes, and shower time 10 seconds.
(Evaluation criteria)
4: Deterioration of the top coat is minimal, and the transparency of the surface layer is maintained.
3: Deterioration of the top coat is rather small, and transparency of the surface layer is slightly decreased.
2: The top coat is somewhat deteriorated, and the transparency of the surface layer is greatly reduced. 1: The top coat is significantly deteriorated, and not only the surface layer but also the base material is destroyed.

The evaluation results of the decorative sheets using the active energy ray-curable building material coatings 1 to 21 are shown in Tables 1 and 2.
All values in the table are given in terms of solid content, except for ethyl acetate.

The abbreviations in the table are as follows:
FINEX-50S-LP2 (zinc oxide in which untreated zinc oxide (average particle size 20 nm) is treated only with hydrogen dimethicone, and the mass ratio of the hydrogen dimethicone-treated layer is about 4% of the total amount)
FINEX-50W (zinc oxide that is untreated (average particle size 20 nm) and is only coated with a high-density silica layer, with the mass ratio of the treated layer being approximately 21% of the total mass)
・FINEX-50 (untreated zinc oxide (average particle size 20 nm) coated with a high-density silica layer and zinc oxide that has not been treated with hydrogen dimethicone)
FINEX-52W-LP2 (zinc oxide in which untreated zinc oxide (average particle size 20 nm) is coated with a high-density silica layer and treated with hydrogen dimethicone, the mass ratio of the high-density silica layer being 10% of the total, and the mass ratio of the hydrogen dimethicone layer being 4% of the total)
MA-500: zinc oxide without surface treatment, average particle size 25 nm, manufactured by Teika Co., Ltd.

The decorative sheet using the active energy ray-curable building material coating of the present invention has excellent UV curing properties and weather resistance.

Claims (7)

The active energy ray curable building material coating material is characterized by containing an acrylic resin containing a (meth)acryloyl group and having a double bond equivalent of 100 to 750 g/mol, and zinc oxide treated with hydrogen dimethicone and having an average particle size of 0.5 to 500 nm . The active energy ray-curable building material coating according to claim 1, wherein the weight average molecular weight of the acrylic resin containing the (meth)acryloyl group is 10,000 to 100,000. The active energy ray-curable building material coating according to claim 1 or 2, wherein the glass transition temperature (Tg) of the acrylic resin containing the (meth)acryloyl group is in the range of 40 to 130°C and the hydroxyl value is 5 to 300 mgKOH/g. The active energy ray curable building material coating material according to any one of claims 1 to 3 , wherein the content of the zinc oxide is 1 to 50 mass % of the total solid content of the active energy ray curable building material coating material. 5. The active energy ray-curable building material coating material according to claim 1 , further comprising an acrylic (meth)oligomer and/or a urethane (meth)acrylate resin. A decorative sheet using the active energy ray-curable building material coating material according to any one of claims 1 to 5 . A method for producing a coated building material having an active energy ray-curable coating on a building material substrate, the method comprising the steps of: applying the active energy ray-curable building material coating material according to any one of claims 1 to 5 to the building material substrate; and irradiating the substrate with active energy rays.