JP2003105230A - Composition for active energy ray curing coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for an active energy ray curing coating material with which a cured coating film having high hardness and a ductility to control a cracking can be obtained. SOLUTION: This composition contains an epoxyacrylate resin (A), which is obtained by reacting a lactone adduct to an hydroxyalkyl (meth)acrylate (a1) with a dicarboxylic anhydride (a2) and an epoxy resin (a3), and a radically polymerizable monomer (B).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an active energy ray-curable coating composition containing an epoxy acrylate resin having a lactone-derived structure.

[0002]

2. Description of the Related Art In recent years, active energy ray curable resins that are cured by ultraviolet rays or electron beams are (1) fast curable.
It is highly evaluated as a coating composition from the viewpoints of (2) low energy cost, and (3) pollution-free by solvent-free.

As the active energy ray curable resin, for example, epoxy acrylate obtained by adding acrylic acid to an epoxy resin is used in the fields of woodwork paints and plastic paints. Although the coating film obtained from the epoxy acrylate has a high hardness, the coating film does not have sufficient elongation (elongation) and cracks easily occur due to stress. In particular, in recent years, the number of cheap imported plywood with weak materials has increased in the woodworking field.This imported plywood has a large internal distortion, and the elongation of the coating film can withstand the distortion of the plywood under severe cold conditions. However, there is a problem that cracking of the coating film becomes more remarkable.

To address the above problems, a half-ester compound (A) obtained by reacting a hydroxyalkyl (meth) acrylate with a dicarboxylic acid anhydride, and an epoxy resin having an average of 1.0 or more glycidyl groups in the molecule. An active energy ray resin composition containing a modified epoxy resin having an acid value of 10 or less obtained by reacting with (B) is disclosed in JP-A-5-70.
It is described in Japanese Patent Publication No. 560. However, although the coating composition comprising the resin composition has tried to impart flexibility to the coating film and improve the elongation, it cannot sufficiently suppress the occurrence of cracks.

[0005]

The problem to be solved by the present invention is to provide an active energy ray-curable coating composition which gives a cured coating film having high hardness and elongation that suppresses the occurrence of cracks. That is.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that in the above composition, an active energy ray-curable coating composition containing a compound in which a lactone is added to hydroxyalkyl (meth) acrylate as a constituent component. It has been found that the composition for use has a high hardness of the coating film, has an elongation and can suppress the occurrence of cracks, and has completed the present invention.

That is, the present invention relates to an epoxy acrylate resin (A) obtained by reacting a lactone adduct (a1) of hydroxyalkyl (meth) acrylate with a dicarboxylic acid anhydride (a2) and an epoxy resin (a3). The present invention provides an active energy ray-curable coating composition, which contains a radically polymerizable monomer (B) as an essential component.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The lactone adduct (a1) of hydroxyalkyl (meth) acrylate used in the present invention is obtained by ring-opening addition of lactone to hydroxyalkyl (meth) acrylate.

Examples of the hydroxyalkyl (meth) acrylate used in preparing the lactone adduct (a1) of hydroxyalkyl (meth) acrylate include:
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like can be mentioned.

Examples of the lactone include β-propiolactone, β-butyrolactone, γ-butyrolactone,
γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone and the like can be mentioned.

The lactone adduct of hydroxyalkyl (meth) acrylate (a1) is preferably a lactone adduct of 2-hydroxyethyl acrylate, and among them, an average of 2 mol of lactone is added to 1 mol of 2-hydroxyethyl acrylate. Is more preferable. Furthermore, 2
An ε-caprolactone adduct of -hydroxyethyl acrylate is preferred, and an ε-caprolactone 2 mol adduct of 2-hydroxyethyl acrylate is most preferred from the viewpoint of the performance of a cured coating film.

Incidentally, 2-hydroxyethyl acrylate with 2 mol of ε-caprolactone, 2-hydroxyethyl acrylate with 3 mol of ε-caprolactone and the like are commercially available.

The above-mentioned lactone adduct (a1) of hydroxyalkyl (meth) acrylate can be used alone or in combination of two or more kinds.

The dicarboxylic acid anhydride (a used in the present invention
Examples of 2) include maleic anhydride, phthalic anhydride, succinic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride. Of these, phthalic anhydride is preferable. The dicarboxylic acid anhydride (a2) can be used alone or in combination of two or more kinds.

Examples of the epoxy resin (a3) used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and aromatic rings of bisphenol type epoxy resin. And hydrogenated.

The epoxy resin (a3) is preferably an epoxy resin having an average of 1.5 or more, preferably 2 to 5 epoxy groups in one molecule. Among the above epoxy resins, a bisphenol type epoxy resin is preferable because it can form a cured coating film having an excellent balance of hardness and elongation. Further, the epoxy resin (a3) can be used alone or in combination of two or more kinds.

Next, a method for producing the epoxy acrylate resin (A) will be described. The epoxy acrylate resin used in the present invention can be prepared by various manufacturing methods, and the manufacturing method and raw materials are not limited. For example, a method in which all of the lactone adduct (a1) of hydroxyalkyl (meth) acrylate, the acid anhydride (a2) and the epoxy resin (a3) are charged and a batch reaction is performed, or a lactone adduct of hydroxyalkyl (meth) acrylate is used. (A1) and dicarboxylic acid anhydride (a2) are subjected to a half-esterification reaction at 110 to 130 ° C. When the half-esterification is almost completed, an epoxy resin (a3) is charged and a reaction between a carboxyl group and an epoxy group is performed. At 80 to 130 ° C. to obtain the epoxy acrylate resin (A). In the present invention, the latter production method can be preferably used. In the latter production method, hydroxyalkyl (meth) during the reaction
Acrylate lactone adduct (a1) and acid anhydride (a
The ratio of the reaction of 2) is [(a1)] / [(a2)] = 1.0 /
It is 0.9-1.0 / 1.1 (molar ratio). Also, (a
The ratio of the reaction between the reaction product of 1) and (a2) and (a3) is
[Carboxyl group possessed by the reaction product of (a1) and (a2)]
/ [(Epoxy group possessed by a3)] = 1.0 / 0.9-
It is 1.0 / 1.1 (molar ratio).

The epoxy acrylate resin (A) used in the present invention includes a lactone adduct (a1) of hydroxyalkyl (meth) acrylate and a dicarboxylic acid anhydride (a).
Any compound can be used without limitation as long as it is obtained by reacting 2) with the epoxy resin (a3), but the content of the lactone-derived structure in the epoxy acrylate resin (A) is 1 kg of the epoxy acrylate resin (A). For 1.0 to
The amount of 3.0 mol is preferable because the elongation and hardness of the coating film are good.

The acid value of the epoxy acrylate resin (A) is preferably less than 2 mg / KOH.

In the method for producing the epoxy acrylate resin (A), as the catalyst used for the reaction between the carboxyl group and the epoxy group, various catalysts such as tertiary amine type and phosphorous acid type can be used. .

Further, when preparing the epoxy acrylate (A), an organic solvent, a radical-polymerizable monomer having no site reacting with a carboxyl group and an epoxy group, or the like can be used if necessary.

Examples of the organic solvent include butyl acetate, methyl isobutyl ketone, toluene and xylene.

The radical-polymerizable monomers containing no site that reacts with the carboxyl group and the epoxy group are:
For example, N-vinylpyrrolidone, acryloylmorpholine, dicyclopentadienyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate,
Dicyclopentenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, isobornyl (meth) acrylate, mono (meth) acrylate of bisphenol F, alkylene oxide-added bisphenol F Mono (meth) acrylates such as mono (meth) acrylates;

Ethylene glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dimethylol tricyclodecane diacrylate, tripropylene glycol di (Meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, alkylene oxide addition 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) Acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, di (meth) hydroxypivalic acid neopentyl glycol ester
Acrylate, bisphenol A di (meth) acrylate, bisphenol F di (meth) acrylate, alkylene oxide-added bisphenol A di (meth)
Di (meth) acrylates such as acrylates and alkylene oxide-added bisphenol F di (meth) acrylates;

Tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate, alkylene oxide-added trimethylolpropane tri (meth) acrylate and pentaerythritol triacrylate;

Hexaacrylate of dipentaerythritol and the like can be mentioned.

The radically polymerizable monomer (B) used in the present invention is, for example, N-vinylcaprolactam,
N-vinylpyrrolidone, N-vinylcarbazole, vinylpyridine, N, N-dimethyl (meth) acrylamide, acrylamide, acryloylmorpholine, 7-amino-3,7-dimethyloctyl (meth) acrylate, isobutoxymethyl (meth) acrylamide , T-
Octyl (meth) acrylamide, diacetone (meth)
Acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, lauryl (meth) acrylate, dicyclopentadienyl (meth) acrylate, dicyclopentenyloxyethyl (meth)
Acrylate, dicyclopentenyl (meth) acrylate, tetrachlorophenyl (meth) acrylate, 2-
Tetrachlorophenoxyethyl (meth) acrylate,
Tetrahydrofurfuryl (meth) acrylate, tetrabromophenyl (meth) acrylate, 2-tetrabromophenoxyethyl (meth) acrylate, 2-trichlorophenoxyethyl (meth) acrylate, tribromophenyl (meth) acrylate, 2-tribromophenoxy Ethyl (meth) acrylate, phenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, pentachlorophenyl (meth) acrylate,
Pentabromophenyl (meth) acrylate, bornyl (meth) acrylate, methyltriethylenediglycol (meth) acrylate, isobornyl (meth) acrylate, bisphenol F mono (meth) acrylate, alkylene oxide adduct bisphenol F mono (meth) acrylate ;

Various phosphoric acid group-containing vinyl monomers such as mono {2- (meth) acryloyloxyethyl} acid phosphate; vinyl sulfonic acid, allyl sulfonic acid, 2
-Methyl allyl sulfonic acid, 4-vinylbenzene sulfonic acid, 2- (meth) acryloyloxyethane sulfonic acid, 3- (meth) acryloyloxypropane sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and other sulfonic acids Group-containing vinyl monomers;

CH₂= CHCOO (CH₂)₃[Si (C
H₃)₂O]_nSi (CH₃)₃, CH₂= C (CH₃) CO
OC₆H_Four[Si (CH₃)₂O)_nSi (CH₃)₃, CH₂
= C (CH₃) COO (CH₂)₃[Si (CH₃)₂O]_n
Si (CH₃)₃, CH₂= C (CH₃) COO (CH₂)₃
[Si (CH₃) (C₆H_Five) ○]_nSi (CH₃)₃,is there
I'm CH₂= C (CH₃) COO (CH₂)₃[Si (C₆
H_Five)₂O]_nSi (CH ₃)₃(However, n in each formula is 0
Or it shall be an integer of 1 to 130. ) Etc.
Various polysiloxane bonds represented by such general formulas
Contained monomers;

Γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxy Silane, γ- (meth) acryloyloxypropyltriisopropenyloxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyl (tris-β-methoxyethoxy) silane, vinyltriacetoxysilane, vinyltrichlorosilane or N-β- (N-vinylbenzylaminoethyl) -γ-
Aminopropyltrimethoxysilane and its hydrochloride salt;
2-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and other (meth) acrylic acid esters having a hydroxyl group, and these monoesters. Ε-caprolactone adduct of a monomer;

Various vinyl ethers having a tertiary amine such as 2-dimethylaminoethyl vinyl ether, 2-diethylaminoethyl vinyl ether, 4-dimethylaminobutyl vinyl ether, 4-diethylaminobutyl vinyl ether and 6-dimethylaminohexyl vinyl ether; 2-hydroxyethyl Vinyl ethers having various hydroxyl groups such as vinyl ether, 4-hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether; or 2-hydroxyethoxyallyl ether,
Allyl ethers having a hydroxyl group such as 4-hydroxybutoxyallyl ether, trimethylolpropane mono- or di-allyl ether, pentaerythritol mono- or di-allyl ether, and ε-caprolactone of these monomers Additives: methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, iso-butyl vinyl ether, 2-ethylhexyl vinyl ether,
Vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether;

Ethylene glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tricyclodecane di (meth) acrylate, dimethylol Tricyclodecane diacrylate, tripropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth)
Acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, bisphenol A
Or di (meth) acrylate of F, alkylene oxide-added bisphenol A or di (meth) acrylate of F; various divalent carboxylic acids such as various unsaturated dibasic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid Bifunctional monomers such as divinyl esters:

Tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate, alkylene oxide-added trimethylolpropane tri (meth) acrylate and pentaerythritol triacrylate;

Hexaacrylate of dipentaerythritol and the like can be mentioned.

As the radically polymerizable monomers (B),
Mono (meth) acrylate and / or di (meth) acrylate are preferable in terms of excellent crack resistance. Among them, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate,
Polypropylene glycol di (meth) acrylate and neopentyl glycol di (meth) acrylate are more preferable.

The amount of the radically polymerizable monomers (B) used is a good balance between the hardness and the elongation of the cured coating film, so that the epoxy acrylate resin (A) and the radically polymerizable monomers ( 10 to 70 per 100 parts by weight of B) in total
It is preferably part by weight.

The trifunctional or higher functional (meth) acrylate such as tri (meth) acrylate or hexa (meth) acrylate is 20 weight% of the total amount of the epoxy acrylate resin (A) and the radical polymerizable monomer (B). It is preferably used within the range of%.

The active energy ray-curable coating composition of the present invention comprises a photoinitiator, an organic solvent, natural or synthetic polymer substances, active energy ray-curable resins, and the like, depending on the purpose.
Fillers, pigments, polymerization inhibitors and the like may be used.

Examples of the above-mentioned photoinitiator include benzophenone, benzyl, Michler's ketone, thioxanthone, anthraquinone and the like compounds which generate radicals by hydrogen abstraction. In general,
A tertiary amine such as methylamine, diethanolamine, N-methyldiethanolamine or tributylamine is used in combination with these compounds. For other types,
For example, compounds of the type that generate radicals by intramolecular splitting, such as benzoin, dialkoxyacetophenone, acyl oxime ester, benzyl ketal,
Examples thereof include hydroxyalkylphenone and halogenoketone.

The amount of the photoinitiator used in the active energy ray-curable coating composition of the present invention is such that the cured film is not colored and can be sufficiently cured, so that the active energy ray-curable coating composition is used. 0.1 to 1 in 100 parts by weight of the solid content of the product
It is preferably 0 part by weight.

Examples of the organic solvent include butyl acetate, methyl isobutyl ketone, toluene and xylene.

Examples of the above-mentioned natural or synthetic polymer substances include various other vinyl ester resins, polyisocyanate compounds, polyepoxides, acrylic resins, alkyd resins, urea resins, melamine resins, polyacetic acid. Vinyl, vinyl acetate-based copolymers, polybutadiene-based elastomers, saturated polyesters, saturated polyethers, nitrocelluloses, cellulose derivatives such as cellulose acetate butyrate; linseed oil, tung oil,
Examples include oils and fats such as soybean oil, castor oil, and epoxidized oils.

Examples of the active energy ray curable resins include unsaturated polyester resins, urethane acrylate resins, epoxy acrylate resins and the like.

Examples of the filler include calcium carbonate, talc, mica, clay, silica powder, colloidal silica, aluminum hydroxide, zinc stearate and the like.

Examples of the pigment include zinc white, titanium white, red iron oxide, and azo pigment.

Examples of the above-mentioned polymerization inhibitors include hydroquinone, methoxyhydroquinone, benzoquinone, toluhydrnoquinone, paratertiarybutylcatechol and the like.

In the present invention, the active energy ray means
Of electromagnetic waves or charged particle beams, those having energy quantum capable of polymerizing and cross-linking molecules are usually used, and ultraviolet rays, electron beams, etc. are usually used, and in the case of ultraviolet rays, ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp A light source such as a carbon arc, a black light lamp, or a metal halide lamp can be used. UV wavelength is usually 1900-38
The wavelength range of 00 Å is mainly used.

In the case of an electron beam, an irradiation source such as a Cockloft-Walton type, a Van de Graaff type, a resonance transformer type, an insulating core transformer type, or a linear type, a dynamitron type, a high frequency type, etc. Can be used, and can be 100 to 1000 KeV, preferably 100
Irradiate with electrons having an energy of ~ 300 KeV. The irradiation dose is usually preferably about 0.5 to 30 Mrad.

The active energy ray-curable coating composition of the present invention is applied using various coating methods such as conventional air spray, airless spray, electrostatic coating, roll coater and flow coater, and various energy is applied. The coating film is cured by irradiating a ray, and the coated article can be used as a building interior or exterior material.

[0050]

EXAMPLES The present invention will now be described in more detail with reference to examples. In the following, all parts and% are by weight unless otherwise specified.

Example 1 (Preparation of active energy ray-curable coating composition) In a 1-liter flask equipped with a stirrer, a gas introduction tube, a condenser, and a thermometer, 2 mol of ε-caprolactone was added to 2-hydroxyethyl acrylate. [Plaxel F
A2D; manufactured by Daicel Chemical Industries, Ltd.] 344 parts, 148 parts of phthalic anhydride, 0.3 parts of methoxyhydroquinone,
The temperature was raised to 120 ° C. and the reaction was performed for 3 hours. After that, it is cooled to 80 ° C and bisphenol A type epoxy resin [EPICL
ON850; manufactured by Dainippon Ink and Chemicals, Inc.] 189
And 4 parts of N, N-dimethylbenzylamine were added,
The temperature was raised to 0 ° C., and the reaction was continued until the acid value became 2 mg / KOH or less. After the reaction was completed, 170 parts of polyethylene glycol 400 diacrylate and 43 parts of 1-hydroxy-cyclohexyl-phenyl ketone (IRGACURE 184, manufactured by Ciba Geigy) were uniformly mixed to obtain an active energy ray-curable coating composition (I1). It was

Example 2 (same as above) In a 1 liter flask equipped with a stirrer, gas inlet tube, condenser, and thermometer, 302 parts of 2-hydroxyethyl acrylate containing 1 mol of γ-butyrolactone, 207 parts of phthalic anhydride and methoxy were added. 0.3 part of hydroquinone was added, the temperature was raised to 120 ° C., and the reaction was carried out for 3 hours. Then 80
After cooling to ℃, 265 parts of EPICRON 850, N,
4 parts of N-dimethylbenzylamine was added, the temperature was raised to 110 ° C., and the reaction was continued until the acid value became 2 mg / KOH or less. After completion of the reaction, tripropylene glycol diacrylate 2
00 parts and 1-hydroxy-cyclohexyl-phenyl ketone (IRGACURE 184, manufactured by Ciba Geigy) were uniformly mixed to obtain an active energy ray-curable coating composition (I2).

Example 3 (same as above) In a 1 liter flask equipped with a stirrer, a gas inlet tube, a condenser, and a thermometer, 3 mol of ε-caprolactone was added 2-hydroxyethyl acrylate [Praxel F.
A3D; manufactured by Daicel Chemical Industries, Ltd.] 366 parts, phthalic anhydride 118 parts, and methoxyhydroquinone 0.3 part,
The temperature was raised to 120 ° C. and the reaction was performed for 3 hours. Then, it cooled to 80 degreeC, 151 parts of EPICLON850 and 3.2 parts of N, N- dimethylbenzylamine were added, and it heated up at 110 degreeC, and reacted until the acid value became 2 mg / KOH or less. After completion of the reaction, tripropylene glycol diacrylate 1
60 parts and 1-hydroxy-cyclohexyl-phenyl ketone (IRGACURE 184, manufactured by Ciba Geigy) were uniformly mixed to obtain an active energy ray-curable coating composition (I3).

Comparative Example 1 (Preparation of active energy ray-curable coating composition for comparison) Acrylic acid 176 and bisphenol F type epoxy were placed in a 1 liter flask equipped with a stirrer, gas inlet tube, condenser and thermometer. Resin [EPICLON 830; manufactured by Dainippon Ink and Chemicals, Inc.] 461 parts, methoxyhydroquinone 0.3 part, N, N-dimethylbenzylamine 3.4 parts were added, the temperature was raised to 110 ° C., and the acid value was 2 mg / KO.
Reacted until H or less. After completion of the reaction, 159 parts of tripropylene glycol diacrylate, 1-hydroxy-cyclohexyl-phenyl ketone (IRGACURE 18
40 parts, manufactured by Ciba-Geigy Co., Ltd.) were uniformly mixed to obtain an active energy ray-curable coating composition (I'1) for comparison.

Comparative Example 2 (Same as above) In a 1 liter flask equipped with a stirrer, gas inlet tube, condenser, and thermometer, 156 parts of 2-hydroxyethyl acrylate, 200 parts of phthalic anhydride, and 0.3 parts of methoxyhydroquinone were added. In addition, the mixture was reacted at 110 ° C. for 2 hours. After that, 255 copies of EPICLON 850, N, N
-Add 3.1 parts of dimethylbenzylamine, and add 6 parts at 110 ° C.
The reaction was carried out for a period of time until the acid value became 2 mg / KOH or less. After completion of the reaction, 152 parts of tripropylene glycol diacrylate, 1-hydroxy-cyclohexyl-
38 parts of phenyl ketone (IRGACURE 184, manufactured by Ciba-Geigy) was uniformly mixed to obtain an active energy ray-curable coating composition (I′2).

Test Examples 1 to 3 and Comparative Test Examples 1 and 2 Hardness tests and crack resistance of the coating films of the active energy ray-curable coating compositions prepared in Examples 1 to 3 and Comparative Examples 1 and 2 An evaluation was made. The results are shown in Table 1. The coating film is a bar coater No. 30, and a glass plate and oak plywood (10 cm x 1
0 cm, thickness 1 cm) each active energy ray-curable coating composition is applied, and an ultraviolet irradiation device (Nippon Battery Co., Ltd.)
A coating film obtained by irradiating with a high pressure mercury lamp at a strength of 80 W / cm and a conveyor speed of 10 m / min until dry to the touch was used. The hardness test of the coating film and the crack resistance evaluation method are shown below.

(1) Hardness test of coating film: Using a coating film formed on a glass plate, a pencil scratching test specified in JIS K5400 was conducted, and the pencil density symbol when the coating film was broken was expressed. (2) Crack resistance of coating film: Using a coating film formed on oak plywood, a load of 2 cycles is applied with 80 ° C. for 2 hours and −20 ° C. for 2 hours as one cycle, and cracks formed in the coating film I observed. When the number of cracks having a length of 1 cm or more was 10 or less, it was evaluated as ◯ (no crack), and when the number of cracks exceeded 10 was evaluated as x (crack was generated).

[0058]

[Table 1]

[0059]

EFFECT OF THE INVENTION The active energy ray-curable coating composition of the present invention is suitable as a coating material for wood because it gives a cured coating film having high hardness and elongation that suppresses the occurrence of cracks.

Claims (6)

[Claims] 1. A lactone adduct (a1) of a hydroxyalkyl (meth) acrylate and a dicarboxylic acid anhydride (a).
2) An active energy ray-curable coating material containing an epoxy acrylate resin (A) obtained by reacting 2) with an epoxy resin (a3) and a radically polymerizable monomer (B) as essential components. Composition. 2. The composition for active energy ray-curable coating composition according to claim 1, wherein the lactone adduct (a1) of hydroxyalkyl (meth) acrylate is a 2-mol lactone adduct of 2-hydroxyethyl acrylate. 3. The active energy ray-curable coating composition according to claim 1, wherein the lactone adduct (a1) of hydroxyalkyl (meth) acrylate is an ε-caprolactone adduct of 2-hydroxyethyl acrylate. 4. The active energy ray curing according to claim 1, wherein the content of the lactone-derived structure in the epoxy acrylate resin (A) is 1.0 to 3.0 mol with respect to 1 kg of the epoxy acrylate resin (A). Composition for mold coating. 5. The epoxy acrylate resin (A) and the radical polymerizable monomer (B) are contained in a weight ratio (A) /
The active energy ray-curable coating composition according to claim 1, wherein (B) is contained in the range of 30/70 to 90/10. 6. The active energy ray-curable coating composition according to claim 1, wherein the radically polymerizable monomer (B) is mono (meth) acrylate and / or di (meth) acrylate.