Active energy ray curable coating composition, cured coating film and coating

Abstract

This invention provides an active energy ray curable coating composition that can use polyfunctional (meth)acrylate compounds capable of forming (meth)acrylate resins with various properties, and that forms a cured coating film exhibiting excellent adhesion to molded products made from melamine resin. [Solution] This disclosure relates to component (A), which is a polyfunctional (meth)acrylate compound, This is an active energy ray curable coating composition containing component (B), which is a phosphate-modified (meth)acrylate. The present invention provides an active energy ray curable coating composition in which the content of component (B) is 1.0 to 7.0 parts by weight per 100 parts by weight of component (A).

Description

Technical Field

[0001] The present disclosure relates to an active energy ray-curable coating composition, a cured coating film, and a coated article.

Background Art

[0002] Conventionally, curable (meth)acrylate resins having various performance such as hardness, flexibility, toughness, solvent resistance, etc. by combining various skeletal structures have been widely used as coating agents for protecting the surface of molded articles.

[0003] On the other hand, melamine resins are widely used as materials for molded articles such as construction materials (decorative boards, etc.), daily necessities (dinnerware, etc.) and electrical equipment parts (connectors, converters, switchboards, insulators, etc.) because they are excellent in properties such as heat resistance, water resistance, weather resistance or electrical insulation. In recent years, further improvement in scratch resistance and chemical resistance has been demanded, and attempts have been made to coat these surfaces with curable (meth)acrylate resins. However, since the coating film formed from a curable (meth)acrylate resin has poor adhesion to the melamine resin, it has been necessary to provide a primer layer or an adhesive layer to improve the adhesion.

[0004] As a technique for ensuring adhesion to a melamine resin molded article without providing a primer layer or an adhesive layer, for example, Patent Document 1 discloses a decorative board including a layer made of a cured product of a resin composition containing a urethane acrylate resin or an acrylic resin containing two radical-reactive groups and a urethane acrylate resin or an acrylic resin containing six or more radical-reactive groups at a specific ratio, and a melamine resin layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, the decorative panel described in Patent Document 1 achieves adhesion only in resin compositions using specific urethane acrylate resins or acrylic resins, and there were limitations on the types of urethane acrylate resins or acrylic resins that could be selected when trying to adjust the hardness, flexibility, toughness, solvent resistance, and other properties to the desired combination.

[0007] Therefore, the object of this disclosure is to provide an active energy ray curable coating composition that can use a polyfunctional (meth)acrylate compound capable of forming (meth)acrylate resins of various properties, and that forms a cured coating film exhibiting excellent adhesion to molded articles formed from melamine resin. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors of this disclosure have found that a cured coating film exhibiting excellent adhesion to molded articles formed from melamine resin can be obtained in a composition containing component (A), which is a polyfunctional (meth)acrylate compound, and component (B), which is a phosphate-modified (meth)acrylate.

[0009] In other words, the present disclosure provides an active energy ray-curable coating composition comprising a component (A) which is a polyfunctional (meth)acrylate compound and a component (B) which is a phosphate-modified (meth)acrylate, wherein the content of component (B) is 1.0 to 7.0 parts by weight per 100 parts by weight of component (A).

[0010] The aforementioned component (A) preferably contains a polyfunctional (meth)acrylate monomer.

[0011] The component (A) preferably comprises a (meth)acrylate oligomer, and the (meth)acrylate oligomer preferably comprises at least one selected from urethane (meth)acrylate oligomer, polyester (meth)acrylate oligomer, and epoxy (meth)acrylate oligomer.

[0012] The aforementioned component (A) preferably includes a polyfunctional (meth)acrylate polymer.

[0013] The aforementioned active energy ray curable coating composition may contain a photopolymerization initiator.

[0014] The active energy ray curing paint composition may contain 1 to 1,000 parts by weight of a volatile organic solvent per 100 parts by weight of the total of components (A) and (B).

[0015] This disclosure also provides a cured coating film obtained by curing the active energy ray curable coating composition.

[0016] This disclosure also provides a coated object in which a molded article formed from melamine resin is coated with the cured coating film. [Effects of the Invention]

[0017] Because the active energy ray curable coating composition of this disclosure has the above configuration, it is possible to use a polyfunctional (meth)acrylate compound that can form (meth)acrylate resins with various properties, and it is possible to form a cured coating film that exhibits excellent adhesion to molded products made from melamine resin. [Modes for carrying out the invention]

[0018] [Active energy ray curing type paint composition] The active energy ray-curable coating composition of the present disclosure is an active energy ray-curable coating composition containing component (A) which is a polyfunctional (meth)acrylate and component (B) which is a phosphate group-modified (meth)acrylate, and the content of the above component (B) is 1.0 to 7.0 parts by weight with respect to 100 parts by weight of the above component (A). Here, “(meth)acrylate” means “acrylate or methacrylate”.

[0019] <Polyfunctional (meth)acrylate compound (component (A))> The polyfunctional (meth)acrylate compound according to the present application is preferably at least one selected from polyfunctional (meth)acrylate monomers, polyfunctional (meth)acrylate oligomers, and polyfunctional (meth)acrylate polymers.

[0020] (Polyfunctional (meth)acrylate monomer) The polyfunctional (meth)acrylate monomer according to the present disclosure is a polymerizable monomer having two or more (meth)acryloyl groups. The number of (meth)acryloyl groups of the polyfunctional (meth)acrylate monomer is preferably 2 to 6, more preferably 2 to 4.

[0021] The molecular weight of the above polyfunctional (meth)acrylate monomer is preferably 200 to 600, more preferably 200 to 500, and still more preferably 400.

[0022] Among the above polyfunctional (meth)acrylate monomers, specific examples of bifunctional (meth)acrylate monomers include, for example, (poly)ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 4,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, neopentyl glycol dimethacrylate, 3-methyl-1,5-pentanediol diacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, dimethylol tricyclodecane diacrylate, dicyclopentanyl diacrylate, and the like.

[0023] Among the above polyfunctional (meth)acrylate monomers, specific examples of trifunctional (meth)acrylate monomers include, for example, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, tris(2-acryloxyethyl) isocyanurate, ε-caprolactone-modified tris(2-acryloxyethyl) isocyanurate, and the like.

[0024] Among the above polyfunctional (meth)acrylate monomers, specific examples of tetrafunctional (meth)acrylate monomers include, for example, trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, alkyl-modified dipentaerythritol tetra(meth)acrylate, and the like.

[0025] Among the polyfunctional (meth)acrylate monomers mentioned above, specific examples of pentafunctional (meth)acrylate monomers include, for example, dipentaerythritol penta(meth)acrylate and alkyl-modified dipentaerythritol penta(meth)acrylate.

[0026] Among the polyfunctional (meth)acrylate monomers mentioned above, specific examples of hexafunctional (meth)acrylate monomers include, for example, dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0027] The above-mentioned polyfunctional (meth)acrylate monomers may be used individually or in combination of two or more.

[0028] (Multifunctional (meth)acrylate oligomers) The polyfunctional (meth)acrylate oligomers relating to this disclosure have two or more (meth)acryloyl groups (functional groups) in the molecule. The above polyfunctional (meth)acrylate oligomers may be formed by bonding the above polyfunctional (meth)acrylate monomers, or they may be urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyether (meth)acrylate oligomers, etc. Among these, urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, and epoxy (meth)acrylate oligomers are preferred because they facilitate the formation of a uniform coating film.

[0029] The weight-average molecular weight of the polyfunctional (meth)acrylate oligomer, measured by GPC in terms of polystyrene equivalent, is preferably 400 to less than 9,000, more preferably 450 to 7,500, even more preferably 500 to 5,000, particularly preferably 600 to 3,500, and most preferably 700 to 2,000.

[0030] The above-mentioned urethane (meth)acrylate oligomer is a compound having a polyurethane bond and two or more (meth)acryloyl groups (functional groups) within its molecule. Examples include addition reaction products with organic isocyanates, hydroxyl group-containing (meth)acrylic acid esters, and any polyhydric alcohol.

[0031] Examples of the above-mentioned organic isocyanates include aliphatic isocyanates such as butane diisocyanate, pentane diisocyanate, and hexamethylene diisocyanate; alicyclic isocyanates such as cyclohexyl isocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate; and aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate.

[0032] Examples of the hydroxyl group-containing (meth)acrylic acid esters mentioned above include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2,3-hydroxypropyl (meth)acrylate.

[0033] Examples of the polyhydric alcohols mentioned above include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, pentanediol, and butanediol.

[0034] Examples of commercially available urethane (meth)acrylate oligomers include "EBECRYL 230" and "EBECRYL 1290" (both manufactured by Daicel Ornex Co., Ltd.), "CN 929" and "CN 964" (both manufactured by Sartomer Co., Ltd.), and "Shiko UV-1700B," "Shiko UV-3000B," and "Shiko UV-7000B" (all manufactured by Mitsubishi Chemical Corporation).

[0035] The number of (meth)acryloyl groups (functional groups) in the above-mentioned urethane (meth)acrylate oligomer is preferably 2 to 12, more preferably 3 to 10, and even more preferably 4 to 8.

[0036] Furthermore, the tensile strength (breaking strength) of the cured urethane (meth)acrylate oligomer is preferably 5 MPa or higher, more preferably 20 MPa or higher, and even more preferably 40 MPa or higher, given that the cured coating film of this disclosure tends to have excellent adhesion. The upper limit of the tensile strength (breaking strength) is, for example, 100 MPa, preferably 70 MPa. The tensile strength is measured, for example, when the coating is cast onto a glass plate and irradiated at an irradiation dose of 800 mJ / cm². 2 For a cured material (7 cm long, 1 cm wide, 100 μm thick) cured using this method, measurements can be taken with a chuck distance of 2 cm and a tensile speed of 200 mm / s.

[0037] The above-mentioned polyester (meth)acrylate oligomer is a compound having an ester bond and two or more (meth)acryloyl groups (functional groups) in its molecule, and examples include (meth)acrylates of polyester polyols. The above-mentioned (meth)acrylates can be obtained, for example, by an esterification reaction between the hydroxyl groups at the ends of the main chain or in the chain of a polyester polyol obtained by polycondensation of a polybasic acid and a polyhydric alcohol, and (meth)acrylic acid and / or a carboxyl group-containing (meth)acrylic acid ester.

[0038] Examples of the polybasic acids mentioned above include aliphatic polybasic acids such as oxalic acid, succinic acid, malonic acid, adipic acid, sebacic acid, azelaic acid, maleic acid, fumaric acid, itaconic acid, succinic anhydride, and maleic anhydride; alicyclic polybasic acids such as dimer acid, cyclohexanedicarboxylic acid, and tetrahydrophthalic anhydride; and aromatic polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, biphenyldicarboxylic acid, trimellitic acid, and pyromellitic acid.

[0039] Examples of the polyhydric alcohols mentioned above include glycols, hexanediols, diethylene glycols, tripropylene glycols, cyclohexanedimethanol, and polyols.

[0040] Examples of the carboxyl group-containing (meth)acrylic acid esters mentioned above include β-carboxyethyl (meth)acrylate, mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, and (meth)acrylic acid dimer.

[0041] Examples of commercially available polyester (meth)acrylate oligomers include "Arronix M-7100" and "Arronix M-8560" (both manufactured by Toagosei Co., Ltd.), and "EBECRYL 884" and "EBECRYL 1830" (both manufactured by Daicel Ornex Co., Ltd.).

[0042] The number of (meth)acryloyl groups (functional groups) in the above polyester (meth)acrylate oligomer is preferably 2 to 10, more preferably 3 to 9, and even more preferably 4 to 8.

[0043] Furthermore, the acid value of the above-mentioned urethane (meth)acrylate oligomer is preferably 50 mg KOH / g or less, more preferably 45 mg KOH / g or less, and even more preferably 40 mg KOH / g or less. The lower limit is preferably 0.5 mg KOH / g, and more preferably 5 mg KOH / g.

[0044] Furthermore, the tensile strength (breaking strength) of the cured polyester (meth)acrylate oligomer is preferably 5 MPa or higher, more preferably 30 MPa or higher, and even more preferably 50 MPa or higher, given that the cured coating film of this disclosure tends to have excellent adhesion. The upper limit of the tensile strength (breaking strength) is, for example, 100 MPa, preferably 90 MPa. The tensile strength is measured, for example, when the coating is cast onto a glass plate and irradiated at an irradiation dose of 800 mJ / cm². 2For a cured material (7 cm long, 1 cm wide, 100 μm thick) cured using this method, measurements can be taken with a chuck distance of 2 cm and a tensile speed of 200 mm / s.

[0045] Examples of the epoxy (meth)acrylate oligomers mentioned above include addition reaction products of an oxirane ring-containing compound and (meth)acrylic acid and / or a carboxyl group-containing (meth)acrylic acid ester.

[0046] Examples of the oxirane ring-containing compounds mentioned above include aromatic epoxy compounds such as bisphenol-type epoxys, aliphatic epoxy compounds such as diglycidyl ethers of diols having 2 to 20 carbon atoms, and alicyclic epoxy compounds.

[0047] Examples of the carboxyl group-containing (meth)acrylic acid esters mentioned above include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, (meth)acrylic acid dimer, and modified (meth)acrylic acid caprolactam.

[0048] Specific examples of the epoxy (meth)acrylate oligomers mentioned above include, for example, bisphenol-type epoxy acrylate, novolac-type epoxy acrylate, aliphatic-type epoxy acrylate, and glycidyl ester-type acrylate. A commercially available example is "EBECRYL 3701" (manufactured by Daicel Ornex Co., Ltd.).

[0049] The number of (meth)acryloyl groups (functional groups) in the epoxy (meth)acrylate oligomer is preferably 2 to 10, more preferably 2 to 7, and even more preferably 2 to 5.

[0050] Furthermore, the acid value of the epoxy (meth)acrylate oligomer is preferably 15 mg KOH / g or less, more preferably 11 mg KOH / g or less, and even more preferably 7 mg KOH / g or less. The lower limit is preferably 0.5 mg KOH / g, and more preferably 0.9 mg KOH / g.

[0051] Furthermore, the tensile strength (breaking strength) of the cured polyester (meth)acrylate oligomer is preferably 5 MPa or higher, more preferably 30 MPa or higher, and even more preferably 50 MPa or higher, given that the cured coating film of this disclosure tends to have excellent adhesion. The upper limit of the tensile strength (breaking strength) is, for example, 100 MPa, preferably 90 MPa. The tensile strength is measured, for example, when the coating is cast onto a glass plate and irradiated at an irradiation dose of 800 mJ / cm². 2 For a cured material (7 cm long, 1 cm wide, 100 μm thick) cured using this method, measurements can be taken with a chuck distance of 2 cm and a tensile speed of 200 mm / s.

[0052] The above-mentioned polyfunctional (meth)acrylate oligomers may be used individually or in combination of two or more.

[0053] (Polyfunctional (meth)acrylate polymer) The polyfunctional (meth)acrylate polymers relating to this disclosure are polymers having two or more (meth)acryloyl groups (functional groups) in their molecules.

[0054] The above-mentioned polyfunctional (meth)acrylate polymer is a vinyl compound polymer having two or more (meth)acryloyl groups (functional groups) in its side chains. Examples include a reaction product of (meth)acrylic acid ester and oxirane ring-containing (meth)acrylic acid ester to which (meth)acrylic acid and / or carboxyl group-containing (meth)acrylic acid ester are added, or a reaction product of (meth)acrylic acid ester and / or (meth)acrylic acid to which oxirane ring-containing (meth)acrylic acid ester are added.

[0055] Examples of the above-mentioned (meth)acrylic acid esters include alkyl (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, n-amyl (meth)acrylate, s-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and alkyl (meth)acrylate alkoxy-containing esters such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 2-phenoxyethyl (meth)acrylate.

[0056] Examples of the carboxyl group-containing (meth)acrylic acid esters mentioned above include β-carboxyethyl (meth)acrylate, mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, (meth)acrylic acid dimer, and modified (meth)acrylic acid caprolactam.

[0057] Examples of the above-mentioned oxirane ring-containing (meth)acrylic acid esters include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, β-ethylglycidyl (meth)acrylate, vinylbenzylglycidyl ether, allylglycidyl ether, (3,4-epoxycyclohexyl)methyl (meth)acrylate, vinylcyclohexene oxide, and the like.

[0058] Examples of commercially available polyfunctional (meth)acrylate polymers include "EBECRYL 1200" (manufactured by Daicel Ornex Co., Ltd.).

[0059] The number of (meth)acryloyl groups (functional groups) in the above-mentioned polyfunctional (meth)acrylate polymer is preferably 2 to 20, more preferably 2 to 15, and even more preferably 2 to 12.

[0060] Furthermore, the elongation at break of the cured polyfunctional (meth)acrylate polymer is preferably 2% or more, more preferably 5% or more, and even more preferably 7% or more, given that the cured coating film of this disclosure tends to have excellent adhesion. The upper limit of the tensile elongation is, for example, 20%, preferably 15%. The tensile elongation is measured, for example, when the coating is cast onto a glass plate and irradiated at an irradiation dose of 800 mJ / cm². 2 For a cured material (7 cm long, 1 cm wide, 100 μm thick) cured using this method, measurements can be taken with a chuck distance of 2 cm and a tensile speed of 200 mm / s.

[0061] The above-mentioned polyfunctional (meth)acrylate polymers may be used individually or in combination of two or more types.

[0062] The weight-average molecular weight of the above-mentioned polyfunctional (meth)acrylate polymer is preferably 9,000 to 50,000, more preferably 9,500 to 40,000, and even more preferably 9,800 to 30,000, based on polystyrene equivalent values ​​measured by the GPC method.

[0063] Examples of commercially available polyfunctional (meth)acrylate polymers include "EBECRYL 1200" (manufactured by Daicel Ornex Co., Ltd.).

[0064] These polyfunctional (meth)acrylate polymers may be used individually or in combination of two or more types.

[0065] The above-described active energy ray-curable coating composition may contain other resin components (such as monomers, oligomers, polymers (hydroxyl group-containing vinyl compound polymers, etc.) other than component (A)) in addition to the above-described polyfunctional (meth)acrylate compound (component (A)). However, the content of component (A) in the total 100% by weight of component (A) and the other resin components is preferably 90% by weight or more, and more preferably 95% by weight or more, in order to easily obtain excellent adhesion to the cured coating film. The upper limit is preferably 100% by weight, and may be 98% by weight.

[0066] <Phosphorus-modified (meth)acrylate (component (B))> The above-mentioned phosphate-modified (meth)acrylate is a (meth)acrylate compound having a phosphate ester group, for example, a reaction product of a (meth)acrylate compound having a (meth)acryloyl group and a hydroxyl group in one molecule with phosphoric acid. The active energy ray-curable coating composition of this disclosure exhibits excellent adhesion to melamine resin by containing a phosphate-modified (meth)acrylate.

[0067] Compounds having a (meth)acryloyl group and a hydroxyl group in one molecule can be obtained, for example, by reacting (meth)acrylic acid and / or (meth)acrylic acid esters with a polyhydric alcohol (alkylene glycol, glycerin, etc.) in a ratio that leaves the hydroxyl group of the polyhydric alcohol intact, or by adding an alkylene oxide (ethylene oxide, propylene oxide, etc.) to (meth)acrylic acid.

[0068] Examples of commercially available phosphate-modified (meth)acrylates include "EBECRYL 168" (manufactured by Ornex Co., Ltd.), "KAYAMER PM-2", "KAYAMER PM-21", "Light Ester P-1M", "Light Ester P-2M", and "Light Acrylate P-1A(N)" (all manufactured by Kyoeisha Chemical Co., Ltd.) from Nippon Kayaku Co., Ltd., and "JPA-514" (manufactured by Johoku Chemical Industry Co., Ltd.).

[0069] The number of (meth)acryloyl groups (functional groups) in the above-mentioned phosphoric acid-modified (meth)acrylate is preferably 1 to 7, more preferably 1 to 5, and even more preferably 1 to 3. The acid value of the above-mentioned phosphoric acid-modified (meth)acrylate is preferably 400 mg KOH / g or less, more preferably 350 mg KOH / g or less, and even more preferably 300 mg KOH / g or less. The lower limit is preferably 50 mg KOH / g, and more preferably 100 mg KOH / g.

[0070] The content of the above-mentioned phosphoric acid-modified (meth)acrylate is 1.0 to 9.0 parts by weight, preferably 1.2 to 8.0 parts by weight, and more preferably 1.5 to 7.0 parts by weight, per 100 parts by weight of component (A). When the amount of the above-mentioned phosphoric acid-modified (meth)acrylate used is within the above range, excellent adhesion to the cured coating film is more easily obtained.

[0071] <Photopolymerization initiator> The active energy ray curable coating composition of this disclosure may contain a photopolymerization initiator. The photopolymerization initiator is not particularly limited and varies depending on the type of active energy ray and the types of components (A) and (B), but known photoradical polymerization initiators and photocationic polymerization initiators can be used. Examples of the above photopolymerization initiators include α-aminoalkylphenone-based photopolymerization initiators such as N,N-dimethylaminoacetophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-[4-(4-morpholinyl)phenyl]-1-butanone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one; and 2-(acetyloxyiminomethyl)thioxa Examples of photopolymerization initiators include oxime ester-based photopolymerization initiators such as benzophenone-9-one; benzophenone-based photopolymerization initiators such as benzophenone, methylbenzophenone, and o-benzoylbenzoic acid; acylphosphine oxide-based photopolymerization initiators such as diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and ethyl-(2,4,6-trimethylbenzoyl)phenylphosphineate; and acetophenone-based photopolymerization initiators such as acetophenone and 1-hydroxycyclohexylphenyl ketone. Among these, acylphosphine oxide-based photopolymerization initiators and acetophenone-based photopolymerization initiators are preferred. These photopolymerization initiators may be used individually or in combination of two or more.

[0072] The amount of the above-mentioned photoinitiator is preferably 1.0 to 10.0 parts by weight, more preferably 2.0 to 8.0 parts by weight, and even more preferably 3.0 to 6.0 parts by weight, based on 100 parts by weight of the total of components (A) and (B). When the amount of photoinitiator used is within the above range, curing defects are less likely to occur, and odors derived from the photoinitiator are less likely to remain in the cured product.

[0073] The active energy ray curable coating composition of this disclosure may contain a volatile organic solvent, a monofunctional (meth)acrylate as a reactive diluent, and various additives, to the extent that they do not impair the effects of this disclosure.

[0074] Examples of volatile organic solvents include organic solvents whose boiling point at 1.0 atmosphere does not exceed 200°C (e.g., ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, and methoxyethyl acetate; ether solvents such as diethyl ether, ethylene glycol methyl ether, and dioxane; aromatic solvents such as toluene and xylene; aliphatic solvents such as pentane and hexane; halogen solvents such as methylene chloride, chlorobenzene, and chloroform; and alcohol solvents such as isopropanol and butanol).

[0075] The amount of the above-mentioned volatile organic solvent blended is preferably, for example, 1 to 1000 parts by weight, more preferably 10 to 750 parts by weight, and even more preferably 20 to 600 parts by weight, per 100 parts by weight of component (A).

[0076] The monofunctional (meth)acrylate used as a reactive diluent is not particularly limited and includes, for example, methyl (meth)acrylate, ethyl (meth)acrylate, glycerin mono(meth)acrylate, glycidyl (meth)acrylate, dicyclopentenyl (meth)acrylate, n-butyl (meth)acrylate, β-carboxyethyl (meth)acrylate, isobornyl (meth)acrylate, octyl / decyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, cyclihexyl (meth)acrylate, other alkyl (meth)acrylates, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among these, n-octyl (meth)acrylate, isobornyl (meth)acrylate, and octyl / decyl (meth)acrylate are preferred, with n-octyl (meth)acrylate being particularly preferred. Monofunctional (meth)acrylates may be used individually or in combination of two or more.

[0077] The amount of the monofunctional (meth)acrylate blended is preferably 0 to 10 parts by weight, and more preferably 0 to 5 parts by weight, per 100 parts by weight of component (A).

[0078] Other additives include, for example, fillers, dyes and pigments, surface modifiers (silicone-based surface modifiers, fluorine-based surface modifiers, polyacrylate-based surface modifiers, etc., preferably polyacrylate-based surface modifiers), ultraviolet absorbers, light stabilizers, defoamers, dispersants, thixotropy imparters, etc. The amount of these additives blended is preferably, for example, 0 to 10 parts by weight, and more preferably 0.05 to 5 parts by weight, per 100 parts by weight of the total of components (A) and (B).

[0079] The active energy ray curable coating composition of this disclosure can be manufactured by mixing component (A), component (B), and optionally the photopolymerization initiator, volatile organic solvent and / or reactive diluent, and other additives. Known or conventional means of mixing can be used, such as various mixers including dissolvers and homogenizers, kneaders, rolls, bead mills, and rotary stirring devices. The conditions for mixing, such as temperature and rotation speed, are not particularly limited and can be set as appropriate.

[0080] The active energy ray curable coating composition of this disclosure is suitably used for coating molded articles made of melamine resin (including molded articles coated with melamine resin).

[0081] [Cured coating film] The cured coating film of this disclosure is formed from a cured product obtained by curing the above-mentioned active energy ray curable coating composition. The cured coating film can be obtained, for example, by applying the active energy ray curable coating composition of this disclosure to an object such as a substrate, and then curing it by irradiating it with active energy rays such as ultraviolet light or electron beams. Known or conventional methods can be used for application, such as coating methods and casting methods. As a light source for ultraviolet irradiation, for example, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, etc., can be used. The irradiation time of ultraviolet light varies depending on the type of light source, the distance between the light source and the coated surface, and other conditions, but is at most several tens of seconds, and is usually several seconds. After ultraviolet irradiation, heating can be performed as needed to ensure complete curing. On the other hand, in the case of electron beam irradiation, for example, it is preferable to use an electron beam with an energy in the range of 50 to 1000 keV and an irradiation dose of 2 to 5 Mrad. Typically, an irradiation source with a lamp output of about 80 to 300 W / cm is used. Furthermore, the thickness of the cured coating film is typically about 1 to 20 μm, preferably about 3 to 15 μm.

[0082] The cured coating film of this disclosure exhibits excellent adhesion not only to molded articles made of melamine resin, but also to various other articles such as plastic articles made of polyethylene terephthalate (PET), polycarbonate, polymethacrylate, and polyvinyl chloride resin, articles on which metal vapor deposition has been applied to the plastic surface, glass, wood, metal plates, and paper. Therefore, these other articles may also be used as the target material for coating.

[0083] [Coating] The coatings described herein are coatings in which the surface of a molded product made from melamine resin is coated with the above-mentioned cured coating film. Since the above-mentioned coatings have excellent heat resistance, water resistance, weather resistance, electrical insulation, scratch resistance, and chemical resistance, they can be suitably used in applications such as construction materials (decorative panels, etc.), daily necessities (tableware, etc.), and electrical equipment components (connectors, switches, distribution boards, insulators, etc.).

[0084] The configurations and combinations thereof described herein are examples only, and additions, omissions, substitutions, and modifications are permitted as appropriate, without departing from the spirit of this disclosure. Furthermore, this disclosure is not limited by the embodiments, but is limited solely by the claims. [Examples]

[0085] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited in any way by these examples.

[0086] The polyfunctional (meth)acrylates (polyfunctional (meth)acrylate monomers, polyfunctional (meth)acrylate oligomers, polyfunctional (meth)acrylate polymers), phosphate-modified (meth)acrylates, and photopolymerization initiators used in the examples and comparative examples are as follows.

[0087] <Component (A), polyfunctional (meth)acrylate> (Polyfunctional (meth)acrylate monomer) • PETIA: A mixture of pentaerythritol triacrylate (molecular weight 298) and pentaerythritol tetraacrylate (molecular weight 352), product name "PETIA", manufactured by Daicel Ornex Co., Ltd.

[0088] (Multifunctional (meth)acrylate oligomers) • EBECRYL1290: Urethane acrylate oligomer (weight-average molecular weight 1,000, number of functional groups 6, tensile strength of cured product 46 MPa), product name "EBECRYL 1290", manufactured by Daicel Ornex Co., Ltd. • EBECRYL1830: Polyester acrylate oligomer (weight-average molecular weight 1,500, number of functional groups 6, acid value 30 mgKOH / g, tensile strength of cured product 77 MPa), product name "EBECRYL 1830", manufactured by Daicel Ornex Co., Ltd. • EBECRYL3701: Epoxy acrylate oligomer (weight-average molecular weight 850, number of functional groups 2, acid value 5 mg KOH / g, tensile strength of cured product 79 MPa), product name "EBECRYL 3701", manufactured by Daicel Ornex Co., Ltd. • EBECRYL1200: Polyfunctional (meth)acrylate polymer (weight-average molecular weight 10,000, number of functional groups 10, tensile elongation of cured product 10%), product name "EBECRYL 1200", manufactured by Daicel Ornex Co., Ltd.

[0089] <Component (B), phosphate-modified (meth)acrylate> • EBECRYL168: Phosphate-modified methacrylate (1.5 functional groups, acid value 290 mgKOH / g), product name "EBECRYL 168", manufactured by Daicel Ornex Co., Ltd.

[0090] <Photopolymerization initiator> • Omni184: 1-Hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins. • OmniTPO: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, product name "Omnirad TPO H", manufactured by IGM Resins.

[0091] The following describes the preparation of active energy ray-curable coating compositions and methods for evaluating their adhesion, using examples and comparative examples.

[0092] (Example 1) An active energy ray curable coating composition was prepared by mixing 100 parts by weight of urethane acrylate oligomer (EBECRYL1290) as a polyfunctional (meth)acrylate, 3.0 parts by weight of phosphate-modified methacrylate (EBECRYL168), 4.1 parts by weight of photopolymerization initiator (Omni184), and 1.0 part by weight of photopolymerization initiator (OmniTPO) with 1.0 part by weight of BYK-361N (polyacrylate-based surface modifier, product name "BYK-361N", manufactured by Bic Chemie Japan Co., Ltd.) as a surface modifier while stirring, and then adding 400 parts by weight of 2-butanone (MEK) as a volatile organic solvent.

[0093] (Examples 2-6, Comparative Examples 1-7) An active energy ray-curable coating composition was prepared in the same manner as in Example 1, except that the polyfunctional (meth)acrylate, photopolymerization initiator (Omni184, OmniTPO), phosphate-modified methacrylate (EBECRYL168), surface modifier (BYK-361N), and volatile organic solvent were blended to the amounts shown in Table 1.

[0094] [Adhesion] On a melamine-coated board (Standard Test Piece Co., Ltd., SPCC-SD (cationic electrodeposition, white coating), 150mm x 70mm), the active energy ray-curable coating compositions obtained in Examples 1-6 and Comparative Examples 1-7 were applied using a bar coater to a coating thickness of 2 μm after curing. The board was then dried at 100°C for 20 seconds. Next, an ultraviolet irradiation unit (EYE INVERTOR GRANDAGE ECS-4011GX, iGraphics Co., Ltd.) was used to irradiate the board at a peak illuminance of 160 mW / cm². 2 , cumulative light intensity 500 mJ / cm 2 Test specimens coated with a cured coating were prepared by curing the coating under the specified conditions by irradiating it with ultraviolet light. A cross-shaped cut was made on one side of the test specimen using a cutter, and then adhesive tape (manufactured by Nichiban Co., Ltd.) was applied along the cross and peeled off. The adhesion state of the cured coating after peeling was observed visually and evaluated as follows. The results are shown in Table 1. ○: No peeling of the hardened coating film occurred. ×: There was peeling of the hardened coating.

[0095] [Table 1]

[0096] As shown in Examples 1 to 6, the cured coating films obtained by curing the active energy ray-curable coating compositions containing component (B) all exhibited excellent adhesion (○). On the other hand, Comparative Examples 1 to 5, which did not contain component (B), Comparative Example 6, which had a low content of component (B), and Comparative Example 7, which had a high content of component (B), all showed poor adhesion (×).

Claims

1. Component (A), which is a polyfunctional (meth)acrylate compound, This is an active energy ray curable coating composition containing component (B), which is a phosphate-modified (meth)acrylate. The content of component (B) is 1.0 to 7.0 parts by weight per 100 parts by weight of component (A). An active energy ray curing coating composition used for coating molded products made from melamine resin.

2. Component (A), which is a polyfunctional (meth)acrylate compound, This is an active energy ray curable coating composition containing component (B), which is a phosphate-modified (meth)acrylate. The content of component (B) is 1.0 to 7.0 parts by weight per 100 parts by weight of component (A). An active energy ray curable coating composition wherein the acid value of the phosphate-modified (meth)acrylate is 100 to 300 mg KOH / g.

3. Component (A), which is a polyfunctional (meth)acrylate compound, This is an active energy ray curable coating composition containing component (B), which is a phosphate-modified (meth)acrylate. The content of component (B) is 1.0 to 7.0 parts by weight per 100 parts by weight of component (A). The aforementioned polyfunctional (meth)acrylate compound is a polyfunctional (meth)acrylate monomer, The aforementioned polyfunctional (meth)acrylate monomer comprises pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate, and is an active energy ray curable coating composition.

4. The active energy ray curable coating composition according to claim 1 or 2, wherein component (A) comprises a polyfunctional (meth)acrylate polymer.

5. Furthermore, the active energy ray curable coating composition according to any one of claims 1 to 4, comprising a photopolymerization initiator.

6. Furthermore, the active energy ray curable coating composition according to any one of claims 1 to 5, comprising 1 to 1,000 parts by weight of a volatile organic solvent and / or a reactive diluent with respect to 100 parts by weight of the total of component (A) and component (B).

7. A cured coating film obtained by curing an active energy ray curable coating composition according to any one of claims 1 to 6.

8. A coated article, wherein a molded article formed from melamine resin is coated with the cured coating film described in claim 7.

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