JP2001064577A - Topcoating material and its curing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coating film which is cured and dried in a short time by using a coating material containing a polyurethane resin, an ultraviolet- curable resin, and a photopolymerization initiator. SOLUTION: The ultraviolet-curable resin is preferably an amine-modified polyether acrylate. A two-component polyurethane resin based on an acrylic resin polyol and a tolylene diisocyanate polymer is suitable as the polyurethane resin. Preferably, 30 to 80 pts.wt. amine-modified polyether acrylate and a pohopolymerization initiator are compounded based on 10 pts.wt. acrylic resin polyol (solid basis) to give the objective topcoating material. First, a two- component polyurethane undercoating material is applied to a substrate and dried at normal temperature; then, an unsaturated polyester intercoating material is applied, dried, and polished with sandpaper; and the topcoating material is applied, predried at normal temperature, and irradiated with ultraviolet rays to form a cured coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top coat containing a polyurethane resin, an ultraviolet curable resin and a photopolymerization initiator, and a method for curing the same.

[0002]

2. Description of the Related Art Polyurethane-based paints can be easily applied without the need for special coating equipment and can be easily applied.
It also has a good finish and has been widely used as a top coat. However, it takes a long time for the coated surface to dry due to the condensation reaction type paint, and it is necessary to take a long time to move to the next step. For example, in the case of a two-pack polyurethane topcoat, if it is air-dried at room temperature (25 ° C.), a leaving time of 20 hours or more is required to move to the next step. In addition, a standing time of one week or more was required for complete curing.

[0003]

Under the circumstances described above, there has been a demand for an overcoating material which can be cured and dried in a short time and has a beautiful finish.

[0004]

In order to solve these problems, the present inventor has invented a top coat containing a polyurethane resin and an ultraviolet curable resin, and a method for curing the same. That is, it is a topcoat paint characterized by containing a polyurethane resin, an ultraviolet curable resin and a photopolymerization initiator, preferably the ultraviolet curable resin is an amine-modified polyether acrylate,
Preferably, the polyurethane resin is a two-component polyurethane resin, the urethane resin polyol of the polyurethane resin is an acrylic resin polyol, the urethane resin isocyanate is a tolylene diisocyanate polymer, and the amine-modified polyisocyanate. The compounding ratio of the ether acrylate is preferably from 30 to 80 parts by weight, particularly preferably from 40 to 60 parts by weight, based on 100 parts by weight of the resin solid content of the urethane resin polyol.

[0005] A second method of the present invention is a method of curing a topcoat paint, which comprises applying a topcoat containing a polyurethane resin, an ultraviolet curable resin and a photopolymerization initiator, preliminarily drying at room temperature, and then irradiating ultraviolet rays. is there.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[0007] The topcoat paint in the present invention is a paint that uses both a polyurethane resin and an ultraviolet curable resin. The polyurethane-based resin generally refers to generally used polyurethane-based resins, and either a one-pack type or a two-pack type can be used, but a two-pack type polyurethane resin is practically preferable because of its high surface hardness.

On the polyol side of the two-pack type polyurethane resin, any of polyester polyol, acrylic polyol, polyether polyol, epoxy polyol and the like can be generally used, but acrylic polyol is preferred from the viewpoint of discoloration hardness. On the isocyanate side, tolylene diisocyanate (TDI), 4-4 diphenylmethane diisocyanate (XDI), xylylene diisocyanate (HDI), hexamethylene diisocyanate (H
DI), isophorone diisocyanate IPDI), water-soluble XDI (H6XDI), water-soluble MDI (H12MDI)
Polyurethane adduct, partial buret with water or amines, and isocyanate (trimerization), all of which can be used. However, a trimerolpropane (TMP) adduct of tolylene diisocyanate (TDI) is preferred in terms of reactivity and coating film hardness.

As the ultraviolet curing resin used in the present invention, epoxy acrylate, urethane acrylate, unsaturated polyester, polyester acrylate, polyether acrylate, silicon acrylate, polybutadiene acrylate, polystyrylethyl methacrylate and the like can be used. In consideration of the ultraviolet curing reaction without inhibiting the reaction, polyether acrylate is preferable as the resin, and amine-modified polyether acrylate is particularly preferable.

The photopolymerization initiator is not particularly limited as long as it generates a radical by the action of light, but the use of a hydroxy group-containing phenyl ketone compound is preferred. Specifically, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1
-Phenylpropan-1-one, 1- (4-isopropylenephenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane-1 -One, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-
Propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxypropyl phenyl ketone,
2-hydroxypropyl-4-isobutylphenylketone, 2-methyl-1- [4- (methylthio) phenyl]
-2-morpholinopropane-1-benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyldimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4
-Benzoyl-4'-methyldiphenyl sulfide,
3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberon, 2- Ethyl anthraquinone, 4 ', 4 "-
Diethylisophthalophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, α-acyloxime ester, acylphosphine oxide, methylphenylglyoxylate, 9,10-
Phenanthrenequinone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, and the like. Among these photopolymerization initiators, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether,
4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-
Methyl-1-phenylpropan-1-one is suitably used, and 1-hydroxycyclohexylphenyl ketone is particularly preferred.

[0011] As an auxiliary agent for the photopolymerization initiator, triethanolamine, triisopropanolamine, 4,4'-
Dimethylaminobenzophenone (Michler's ketone),
4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy)
Ethyl, isoamyl 4-dimethylaminobenzoate, 4-
2-ethylhexyl dimethylaminobenzoate, 2,4-
It is also possible to use diethylthioxanthone, 2,4-diisopropylthioxanthone or the like in combination.

The mixing ratio of the resin in the top coat of the present invention is not particularly limited. However, in order to obtain the effects of the present invention efficiently, the mixing ratio of the amine-modified polyether acrylate should be not more than 10% of the resin solid content of the urethane resin polyol.
It is preferably from 30 to 80 parts by weight, particularly preferably from 40 to 60 parts by weight, based on 0 parts by weight. If the amount is less than 30 parts by weight, the curability when irradiated with ultraviolet light is poor, and the thinner resistance and the solvent resistance cannot be provided.If the amount exceeds 80 parts by weight, the ultraviolet curable resin inhibits the reaction of the urethane resin,
Urethane reaction hardly occurs, and thinner resistance and solvent resistance become poor.

[0013] The top coat obtained in this manner is usually coated with a two-pack polyurethane undercoat on a substrate, dried at room temperature for 5 hours, coated with an unsaturated polyester intermediate coat, and then left at room temperature for 18 hours. It is dried, polished with # 400 sandpaper, and then applied. After applying the top coat, it is necessary to dry at room temperature for 2 hours and then irradiate with ultraviolet rays for 2 seconds. Here, UV is 150-45
The method mainly uses light in a wavelength range of 0 nm, and examples of the method include irradiation using a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, or the like.

[0014] The top coat of the present invention is
As long as the effects of the present invention are not impaired, an antifoaming agent, a flame retardant, an antistatic agent, a plasticizer, a filler (such as finely divided silica),
Contains leveling agents (silicone, cellulose acetate butyrate, surfactants, etc.), stabilizers, anti-sagging agents (hydrogenated castor oil, fine silica, etc.), matting agents (fine silica powder, polyethylene wax, etc.) It is also possible.

As the diluent, there can be used ethyl acetate, toluene, xylene, butanol, acetone, methyl isobutyl ketone, methyl ethyl ketone, cellosolves, diacetone alcohol, acrylate, alkyl vinyl ketone and the like.

[0016]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the gist of the present invention is not limited thereto.

(Example 1) Hitaloid D-1004Z-1 (manufactured by Hitachi Chemical Co., Ltd.) as a polyol 20
0 g, 44 g of CAB-381-05 (manufactured by Eastman Chemical Japan Co., Ltd.), and 156 g of methyl isobutyl ketone were weighed, transferred to a container, and dissolved well. Further, Laromer PO-83 is used as an ultraviolet curable resin.
70 g of F (manufactured by BSF Japan Co., Ltd.) was weighed and transferred to a container containing polyol. afterwards,
288 g of butyl acetate was weighed, placed in the container, and stirred well. As a matting agent, 210 g of X-5025 (manufactured by Gifu Shellac Manufacturing Co., Ltd.) and MATTING AGEN
14 g of TOK-412 (manufactured by Degussa Japan)
Was placed in the container and stirred for 30 minutes. Thereafter, 3 g of BYK-300 (manufactured by Big Chemie Japan) as a leveling agent and Irgacure 18 as a photoinitiator.
4 (manufactured by Nippon Ciba Geigy Co., Ltd.) was placed in the container, stirred for 15 minutes and dissolved to prepare 1 kg of a main agent. Next, as an isocyanate prepolymer, Coronate L-75 (manufactured by Nippon Polyurethane Industry Co., Ltd.) 500
g was weighed and transferred to a container. Then, butyl acetate 500
g was weighed, placed in a container containing the isocyanate prepolymer, and stirred well to prepare 1 kg of a curing agent. Immediately before coating, the main agent and the curing agent were mixed so that the weight ratio became 4: 1 and used as a paint. The above paint was spray-coated with an upper cup gun to obtain a coating amount of 60 g / m ² . After standing at room temperature (25 ° C.) for 2 hours, one high-pressure mercury lamp (80 W / cm) was put on a 3.0 m / min belt conveyor under lighting, passed through, and dried.

(Comparative Example 1) Hitaloid D-1004Z-1 (manufactured by Hitachi Chemical Co., Ltd.) as a polyol 20
0 g, 44 g of CAB-381-05 (manufactured by Eastman Chemical Japan Co., Ltd.), and 156 g of methyl isobutyl ketone were weighed, transferred to a container, and dissolved well. Thereafter, 373 g of butyl acetate was weighed, placed in a container containing a polyol, and stirred well. As a matting agent, 210 g of X-5025 (manufactured by Gifu Shellac Manufacturing Co., Ltd.) and MATTING AGENT OK-4
14 (manufactured by Degussa Japan KK) was placed in the container and stirred for 30 minutes. Then, BYK-300 (manufactured by Big Chemie Japan) as a leveling agent
3 g was placed in the container, stirred for 15 minutes, and dissolved to prepare 1 kg of a main ingredient. The curing agent prepared in Example 1 was used. Immediately before coating, the main agent and the curing agent were mixed so that the weight ratio became 4: 1 and used as a paint. Spray the above paint with upper cup gun, 60g / m
A coating weight of ² was obtained. It was dried at normal temperature (25 ° C.) for 2 hours.

Comparative Example 2 Hitaloid D-1004Z-1 (manufactured by Hitachi Chemical Co., Ltd.) as a polyol 20
0 g, 44 g of CAB-381-05 (manufactured by Eastman Chemical Japan Co., Ltd.), and 156 g of methyl isobutyl ketone were weighed, transferred to a container, and dissolved well. Furthermore, Laromer PO-
83g (BSF Japan Co., Ltd.) 30g
Was weighed and transferred to a container containing the polyol. Thereafter, 336 g of butyl acetate was weighed, placed in the container, and stirred well. As a matting agent, 210 g of X-5025 (manufactured by Gifu Shellac Co., Ltd.) and MATTING AG
ENT OK-412 (made by Degussa Japan Co., Ltd.) 1
4 g was placed in the vessel and stirred for 30 minutes. Thereafter, 3 g of BYK-300 (manufactured by Big Chemie Japan Co., Ltd.) as a leveling agent and 7 g of Irgacure 184 (manufactured by Nippon Ciba Geigy Co., Ltd.) as a photoinitiator are placed in the container, stirred for 15 minutes, dissolved, and the base material is dissolved. 1 kg was prepared. Next, as an isocyanate prepolymer, Coronate L-75 (manufactured by Nippon Polyurethane Industry Co., Ltd.) 50
0 g was weighed and transferred to a container. Then, butyl acetate 50
0 g was weighed, placed in a container containing the isocyanate prepolymer, and stirred well to prepare 1 kg of a curing agent. Immediately before coating, the main agent and the curing agent were mixed so that the weight ratio became 4: 1 and used as a paint. The above paint was spray-coated with an upper cup gun to obtain a coating amount of 60 g / m ² . After standing at room temperature (25 ° C.) for 2 hours, one high-pressure mercury lamp (80 W / cm) was put on a 3.0 m / min belt conveyor under lighting, passed through, and dried.

(Comparative Example 3) Hitaloid D-1004Z-1 (manufactured by Hitachi Chemical Co., Ltd.) as a polyol 20
0 g, 44 g of CAB-381-05 (manufactured by Eastman Chemical Japan Co., Ltd.), and 156 g of methyl isobutyl ketone were weighed, transferred to a container, and dissolved well. Furthermore, Laromer PO-
83F (BFS Japan Ltd.) 150
g was weighed and transferred to a container containing the polyol. Thereafter, 193 g of butyl acetate was weighed, placed in the container, and stirred well. As a matting agent, 210 g of X-5025 (manufactured by Gifu Shellac Manufacturing Co., Ltd.) and MATTING A
GENT OK-412 (made by Degussa Japan Co., Ltd.)
14 g was placed in the vessel and stirred for 30 minutes. afterwards,
3 g of BYK-300 (manufactured by Big Chemie Japan Co., Ltd.) as a leveling agent and 30 g of Irgacure 184 (manufactured by Nippon Ciba Geigy Co., Ltd.) as a photoinitiator are placed in the container, stirred for 15 minutes, dissolved, and 1 kg of the main agent is added. Prepared. Next, Coronate L-75 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer
500 g was weighed and transferred to a container. Thereafter, 500 g of butyl acetate was weighed, placed in a container containing an isocyanate prepolymer, and stirred well to prepare 1 kg of a curing agent.
Immediately before coating, the main agent and the curing agent were mixed so that the weight ratio became 4: 1 and used as a paint. The above paint was spray-coated with an upper cup gun to obtain a coating amount of 60 g / m ² . After standing at room temperature (25 ° C.) for 2 hours, one high-pressure mercury lamp (80 W / cm) was put on a 3.0 m / min belt conveyor under lighting, passed through, and dried.

(Test Example 1) The top coats produced in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were applied according to the steps shown in Table 1. That is, first, a two-pack type polyurethane undercoat (manufactured by Sanyu Paint Co., Best Sealer) is applied to the surface of oak natural decorative plywood, and an unsaturated polyester intermediate coat (manufactured by Sanyu Paint Co., Ltd., NS-777) is applied thereon. After coating and polishing with # 400 sandpaper, Example 1, Comparative Example 1, Comparative Example 2
Each of the top coats manufactured according to Comparative Example 3 was applied and dried under the respective drying conditions, and the coated surface was evaluated. As shown in Table 2, the results were as in Example 1.
The coated surface of the top coat prepared in the above was excellent in surface hardness, thinner resistance and blocking resistance, but the coated surface of the top coat prepared in Comparative Example 1, Comparative Example 2 and Comparative Example 3 Was also inferior to the case of Example 1. The evaluation criteria for surface hardness, thinner resistance and blocking resistance are as follows:
It is as follows.

(Surface hardness) JIS K-5400
4.2 It was measured by a manual scratching method, and the evaluation was made as a pencil scratch value obtained by abrasion of the coating film.

(Thinner resistance) The JAS special plywood is subjected to a thinner resistance test according to Japanese Agricultural Standards. That is, after the test piece was placed horizontally, lacquer thinner (JIS5538) was dropped on the surface of the test piece, coated with a watch glass for 6 hours, allowed to stand at room temperature for 24 hours, and evaluated according to the following criteria. 10: No abnormality at all. 8: Almost no abnormality. 5: Somewhat swollen, peeled, softened. 3: There is swelling, peeling, and softening. 1: Large swelling, peeling, softening.

(Blocking resistance) A gauze was placed on the dried coating film, and a load of 1 kgf / cm ² was applied thereon to apply
It was left for 4 hours, and those with gauze marks were rejected.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

The topcoat of the present invention can provide a coated surface having excellent surface hardness, blocking resistance and thinner resistance in a short time compared to the conventional two-pack type urethane resin topcoat, and The finish feeling was similar to that of urethane and was more beautiful than that of the UV-curable top coat.

Claims (6)

[Claims] 1. A topcoat comprising a polyurethane resin, an ultraviolet curable resin and a photopolymerization initiator. 2. An overcoat paint, wherein the ultraviolet-curable resin according to claim 1 is an amine-modified polyether acrylate. 3. A topcoat paint, wherein the polyurethane resin according to claim 1 is a two-pack polyurethane resin. 4. The polyurethane resin according to claim 1, wherein the urethane resin polyol is an acrylic resin polyol, and the urethane resin isocyanate is a tolylene diisocyanate prepolymer. And top coat paint. 5. A topcoat paint wherein the compounding ratio of the amine-modified polyether acrylate according to claim 2 or 3 is 30 to 80 parts by weight with respect to 100 parts by weight of the resin solid content of the urethane resin polyol. . 6. A method for curing a top coat, comprising applying a top coat containing a polyurethane resin, an ultraviolet curable resin and a photopolymerization initiator, preliminarily drying at room temperature, and irradiating with ultraviolet rays.