JP2000297112A - Photocurable resin composition, coating and preparation of cured coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocurable resin composition which yields a coated film having an excellent smoothness when applied to plastic substrates, etc., shows an excellent adhesion against isocyanate-cured acrylic polyol coated films and yields a coated film exerting an excellent scuff resistance and flexibility, a coating prepared using it and a preparation process of a cured coating film. SOLUTION: This photocurable resin composition comprises a urethane compound (A) which has three structures having at least two unsaturated double bonds via urethane bonds per molecule, a photopolymerizable monomer (B) of the formula (wherein R is hydrogen or methyl group) and a photopolymerization initiator (C). A coating comprises the photocurable resin composition. In a preparation process of a cured coating film, the coating is applied to a substrate on which an isocyanate-cured acrylic polyol resin coated film is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable resin composition useful as a coating curable by irradiation with ultraviolet rays or electron beams, a coating composition using the same, and a method for producing a cured coating film. In particular, when cured, the photocurable resin composition is excellent in adhesion to the isocyanate-cured acrylic polyol coating film surface, and can form a coating film having excellent pencil hardness and scratch resistance on the surface of the cured coating film, and The present invention relates to a method for producing a paint and a cured coating film using the same.

[0002]

2. Description of the Related Art Conventionally, isocyanate-cured acrylic polyol paints which can be cured at a low temperature have been used for plastic coating. PVC, as plastic substrate
ABS, AS, PC, PET, etc. are used, and isocyanate-cured acrylic polyol, etc., which has excellent adhesion to various substrates, is used to enhance the design properties (coloring, pattern, gloss, etc.). I have. Examples of the application include various home appliances such as vacuum cleaners, telephones, and audio equipment, and stationery-related products.

However, an isocyanate-cured acrylic polyol coating film obtained by curing an acrylic polyol with isocyanate is inferior in surface smoothness, abrasion resistance, chemical resistance, and the like. As a solution, a method of forming a UV-cured coating film on an isocyanate-cured acrylic polyol coating film to improve abrasion resistance, chemical resistance, and the like has been conventionally studied. However, a photocurable resin composition that has a balance between adhesion, abrasion resistance, curability, and flexibility and has excellent coating film smoothness during coating has not been obtained.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a coating film having excellent smoothness when applied to a plastic substrate, etc., excellent adhesion to an isocyanate-cured acrylic polyol coating film, and improved scratch resistance of the coating film. An object of the present invention is to provide a photocurable resin composition which is excellent and has excellent flexibility of a coating film, and a paint using the same. Further, the present invention provides excellent smoothness of a coating film when applied to a plastic substrate, etc., excellent adhesion to an isocyanate-cured acrylic polyol coating film, excellent scratch resistance of the coating film, It is intended to provide a method for producing a cured coating film having excellent flexibility.

[0005]

That is, the present invention provides a urethane compound (A) having a structure having at least two unsaturated double bonds via a urethane bond in one molecule, and a compound represented by the general formula (I):

Embedded image (Wherein, R represents a hydrogen atom or a methyl group). The present invention relates to a photocurable resin composition containing a photopolymerizable monomer (B) represented by the following formula (C) and a photopolymerization initiator (C).

[0006] The present invention further relates to the photocurable resin composition containing a photopolymerizable monomer (D) having an unsaturated double bond. In the present invention, the component (A) is preferably
It is obtained by reacting an isocyanate compound having three isocyanate groups (a) and a hydroxyl group-containing unsaturated compound having two or more unsaturated double bonds and one hydroxyl group in one molecule (b). The present invention relates to a photocurable resin composition.

Further, the present invention provides a photocurable resin composition wherein the isocyanate compound (a) is a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate or a trimer of trimethylhexamethylene diisocyanate hexane methylene diisocyanate. About things. The present invention also relates to a photocurable resin, wherein the hydroxyl group-containing unsaturated compound (b) is pentaerythritol triacrylate, diacrylate of trihydroxyethyl isocyanurate, dimethacrylate of pentaerythritol trimethacrylate or trihydroxyethyl isocyanurate. Composition.

In the present invention, the component (D) may be polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triacrylate of trihydroxyethyl isocyanurate, polypropylene glycol dimethacrylate, pentaerythritol trimethacrylate,
The present invention relates to a photocurable resin composition which is pentaerythritol tetramethacrylate or trihydroxyethyl isocyanurate trimethacrylate.

[0009] The present invention also relates to a paint containing the photocurable resin composition. Further, the present invention relates to a method for producing a cured coating film, which comprises applying the above-mentioned coating material on a substrate on which a coating film of an isocyanate-cured acrylic polyol resin is formed, and curing.

[0010]

First, the urethane compound (A) will be described in detail. Urethane compound (A) used in the present invention
Is a structure having at least two unsaturated double bonds via a urethane bond in one molecule.
By using this urethane compound (A), the resulting coating film is excellent in scratch resistance, coating film appearance, and the like.

The method for producing the urethane compound (A) used in the present invention is not particularly limited. Examples thereof include an isocyanate compound (a) having three isocyanate groups and two or more unsaturated double bonds in one molecule. It can be obtained by reacting a hydroxyl group-containing unsaturated compound (b) having two hydroxyl groups.

The isocyanate compound having three isocyanate groups in one molecule (a) used herein includes tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and tetramethylxylylene. Three molecules of each diisocyanate compound such as diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylylene diisocyanate form an isocyanurate ring to form a trimer. Compounds containing a group are preferred. Among these, considering the handling properties of the obtained urethane compound (A), trimers of isophorone diisocyanate, trimers of hexamethylene diisocyanate or trimers of tetramethylxylylene diisocyanate have low viscosity, It is preferable because of low thixotropy.

Examples of the hydroxyl-containing unsaturated compound (b) having two or more photocurable unsaturated double bonds and one hydroxyl group in one molecule include di (meth) acrylate of trimethylolpropane. And di (meth) acrylate of pentaerythritol tri (meth) acrylate and trihydroxyethyl isocyanurate. Among these, in terms of scratch resistance,
Pentaerythritol tri (meth) acrylate is particularly preferred. In the present invention, (meth) acrylate means acrylate or methacrylate. The urethane compound (A) may be used alone or as a mixture of two or more.

The component (B) is a photopolymerizable monomer represented by the general formula (I). By using this as an essential component, excellent adhesion can be obtained without deteriorating abrasion resistance. Can be obtained. As the photopolymerizable monomer represented by the general formula (I), an acrylate in which R in the general formula (I) is a hydrogen atom is preferable from the viewpoint of reactivity.

The mixing ratio of the component (A) is as follows:
Based on the sum of the component (B) and the component (D) described below, the component (A) is preferably 20 to 70% by weight, and more preferably 30 to 70% by weight.
60% by weight is more preferred. When the proportion of the component (A) is less than 20% by weight, the scratch resistance tends to be inferior.
If it exceeds 0% by weight, the properties of the resulting coating film, such as appearance, adhesion, and scratch resistance, tend to be generally reduced.

The photocurable resin composition of the present invention contains a photopolymerization initiator as the component (C). Examples of the photopolymerization initiator include carbonyl [benzophenone, diacetyl, benzyl, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetone, p-dimethylaminoacetophenone, p
-Dimethylaminopropiophenone, 2-chlorobenzophenone, p, p'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2- Hydroxy-2-methyl-1-one, 1- (4-isopropylphenyl)-
2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 2,2-diethoxyacetophenone, 4-N, N'-dimethylacetophenones, etc.], sulfides (diphenyl disulfide, dibenzyl disulfide, etc.) Quinone (benzoquinone, anthraquinone, etc.), azo (azobisisobutyronitrile, 2,2'-azobispropane, hydrazine, etc.), sulfochloride, thioxanthone, etc., peroxide (benzoyl peroxide, Di-t-butyl peroxide), isoamyl o-dimethylaminobenzoate and the like. These photopolymerization initiators can be used alone or
It can be used in combination of more than one kind.

The amount of these photopolymerization initiators is (A)
1 to 10 parts by weight based on 100 parts by weight of the total of the component, the component (B), the component (C), and the component (D) used as required.
A weight part is preferable and 3-7 weight parts is more preferable. If this amount is less than 1 part by weight, the photocurability is not sufficient and
If the amount exceeds 0 parts by weight, the physical properties of the obtained coating film tend to be generally reduced.

The photocurable resin composition of the present invention may further contain, if necessary, a photopolymerizable monomer (D) having at least one unsaturated double bond. As the photopolymerizable monomer (D), a monofunctional or polyfunctional (meth) acrylate compound or the like can be used.

These photopolymerizable monomers (D) include:
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, n-propyl (meth) acrylate, n
-Butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) ) Acrylate, tridecyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( (Meth) acrylate, 2-methoxyethoxy (meth) acrylate, 2-ethoxyethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydi Tylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, octafluoropentyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, allyl (meth) ) Acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate, polyethylene glycol di (meth)
Acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Tripropylene glycol di (meth) acrylate, hydroxypivalic acid ester neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, 1,3-bis (hydroxyethyl)
-5,5-dimethylhydantoin, 3-methylpentanediol (meth) acrylate, α-, ω-di (meth)
Acrylic bisdiethylene glycol phthalate, trimethylolpropane tri (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol hexa (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, α, ω-tetraallylbistri Methylolpropane tetrahydrophthalate, 2-hydroxyethyl acryloyl phosphate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate,
1,4-butanediol di (meth) acrylate, 1,
Examples thereof include 6-hexanediol di (meth) acrylate, neopentyl glycol dimethacrylate, diacryloxyethyl phosphate, N-vinylpyrrolidone, and the like, and among them, acrylate derivatives are preferable.

Among them, polypropylene glycol di (meth) acrylate, pentaerythritol tri (meth)
Acrylate, pentaerythritol tetra (meth) acrylate or di (meth) acrylate of trihydroxyethyl isocyanurate is preferred from the viewpoint of scratch resistance.

The component (D) may be used alone or as a mixture of two or more. When the component (D) is used,
Based on the sum of the components (A), (B) and (D), the total amount of the components (B) and (D) is 30 to 80.
%, More preferably 40 to 70% by weight. If this amount is less than 30% by weight or 80
When the content exceeds about 10% by weight, properties such as appearance, adhesion, and scratch resistance of the obtained coating film tend to be generally deteriorated. Also,
In this case, the mixing ratio of the component (B) and the component (D) is preferably 10/90 to 30/70 in terms of the former / the latter (weight ratio) in terms of adhesion and abrasion resistance.

The photocurable resin composition of the present invention may further comprise (i) an organic solvent such as a hydrocarbon-based organic solvent, an ester-based organic solvent, a ketone-based organic solvent (if used, (A) (B) preferably 70 parts by weight or less based on 100 parts by weight of the total of components (C) and (D)), (i)
i) unsaturated polyester resin, vinyl ester resin, vinyl urethane resin, vinyl ester urethane resin, polyisocyanate, polyepoxide, epoxy-terminated polyoxazolidone, acrylic resin, alkyd resin, urea resin, melamine resin, polydiene elastomer,
Saturated polyesters, polyethers, nitrocellulose, cellulose derivatives such as cellulose acetate butyrate, and natural and synthetic high molecular substances such as linseed oil, tung oil, soybean oil, castor oil, epoxidized oil, and other fats and oils (used In this case, the sum of the components (A), (B), (C) and (D) is 10
0 parts by weight, preferably 50 parts by weight or less),
(Iii) Various fillers and pigments such as calcium carbonate, talc, mica, clay, silica powder, colloidal silica, barium sulfate, aluminum hydroxide, zinc stearate, zinc white, red iron oxide, azo pigments (when used,
(A) (preferably 10 parts by weight or less based on 100 parts by weight of the total of the components (C) and (D)), (iv) hydroquinone, hydroquinone monomethyl ether, benzoquinone, pt-butylcatechol , 2,6-di-
A polymerization inhibitor such as t-butyl-4-methylphenol (when used, preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the total of components (A), (B), (C) and (D)) Parts by weight) and the like.

The photocurable resin composition of the present invention can be used for a metal material such as iron and aluminum, a calcium silicate plate, a lightweight concrete plate, an asbestos cement plate, an inorganic building material such as mortar, and an ultraviolet ray for wood, paper and plastic base materials. It can be used as a curable paint or printing ink. When used as a paint, a leveling agent and other modifiers can also be added.

The coating composition using the photocurable resin composition of the present invention is applied to a base material on which a coating film of an isocyanate-cured acrylic polyol resin has been formed, and is then applied as a top-coating coating for a method of producing a cured coating film. The cured coating film obtained by this production method is excellent in adhesion, chemical resistance, stain resistance and scratch resistance. A known method such as a method using a bar coater can be applied to the coating method, and is not particularly limited. Curing can be performed by ultraviolet irradiation or electron beam irradiation, and the apparatus, conditions, and the like are not particularly limited.

[0025]

Next, the present invention will be described in detail with reference to examples and comparative examples. In the following, “parts” and “%” are all based on weight unless otherwise specified.

Production Example 1 (Urethane acrylate compound) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, tetramethylolmethane triacrylate (Shin-Nakamura Chemical Co., Ltd. ), Trade name A-TMM-3, hydroxyl value 122) 444 parts, hydroquinone monomethyl ether 0.32 parts, dibutyltin dilaurate (trade name L101, manufactured by Tokyo Fine Chemical Co., Ltd.) 0.64 parts and ethyl acetate 160 parts Was heated to 70 ° C., and then kept at 70 to 75 ° C., and Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd., trimer of hexamethylene diisocyanate, NCO content = 21.1%)
A mixed liquid of 191 parts and 120 parts of ethyl acetate was dropped uniformly over 3 hours to carry out a reaction. When the reaction was allowed to proceed for about 5 hours after the completion of the dropwise addition, the reaction was terminated after confirming that the isocyanate had disappeared as a result of IR measurement.
%, A urethane acrylate compound having a weight average molecular weight of 2,000 was obtained.

Production Example 2 (Urethane acrylate compound) After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, tetramethylolmethane triacrylate (Shin-Nakamura Chemical Co., Ltd. A-TMM-3) 347 parts, 2-hydroxyethyl acrylate 116 parts, hydroquinone monomethyl ether 0.4 parts, dibutyltin dilaurate (trade name L101, manufactured by Tokyo Fine Chemical Co., Ltd.) 0.8 parts and After charging 160 parts of ethyl acetate and raising the temperature to 70 ° C.,
Warmed to Coronate HX (Nippon Polyurethane Industry Co., Ltd.)
298 parts and 120 parts of ethyl acetate.
The reaction was carried out by dropping uniformly over time. After the reaction was completed for about 5 hours after the completion of the dropping, IR measurement confirmed that the isocyanate had disappeared, and the reaction was terminated. The solid content was about 70%.
A urethane acrylate compound having a weight average molecular weight of 1500 was obtained.

Using the urethane acrylate compounds obtained in Production Examples 1 and 2, the composition shown in Table 1 was used to prepare Example 1.
To 3 and Comparative Examples 1 and 2 were prepared.

[0029]

[Table 1]

Application Examples The photocurable resin compositions obtained in the above Examples and Comparative Examples are coated and cured by the method of (2) on an isocyanate-cured acrylic polyol coated plate prepared by the following method (1). Thus, an evaluation test plate was prepared. Irradiation was performed at one 80 w / cm high-pressure mercury lamp, irradiation distance of 15 cm, and conveyor speed of 10 m / min (a single irradiation amount of about 250 mJ / cm ² ).

(1) Preparation of Intermediate, Isocyanate-cured Acrylic Polyol Coating Composition of paint: Hitaloid 3368 / Sumidur N-75
/ Butyl acetate = 100/14/13 (weight ratio) * Hitaloid 3368: acrylic polyol resin, manufactured by Hitachi Chemical Co., Ltd., hydroxyl value = 30 mgKOH / g, Tg = 65
° C, viscosity = 10 poise, heating residue = 50% * Sumidule N-75: isocyanate curing agent, manufactured by Sumitomo Bayer Urethane Co., Ltd., NCO content = 16.4%

Paint curing method: Substrate Transparent rigid PVC plate (Mitsubishi PVC 3001: 0.5 mm ×, manufactured by Japan Test Panel Co., Ltd.)
(200mm x 300mm) Coating method; Bar coater No. 60 drying; 15 minutes in 60 ° C hot air dryer; Curing of coating film;

(2) Method of preparing UV cured coated plate for evaluation Coating; Bar coater No. 8 drying; UV irradiation for 1 minute in a 60 ° C hot air dryer; 80 w / cm 1 high pressure mercury lamp Conveyor speed 10 m / min (UV irradiation Equipment: 6kw, 80w / cm × 2
Light, UV irradiation device; Nippon Battery Co., Ltd. UV irradiation amount:
Conveyor speed 10m / minute is equivalent to 100mJ / cm ² irradiation) measurement equipment: Topcon industrial UV checker UV R-T
35, measurement wavelength range: about 300 to 390 nm)

The coating films thus obtained were subjected to various performance tests. Table 2 shows the results. (1) Appearance of coating film: The smoothness of the coating film surface was visually evaluated. (2) Chemical resistance: The coating film surface was rubbed 50 times using a gauze impregnated with xylene, and the surface condition of the coating film was observed. (3) Magic stain resistance: Draw a straight line with a length of about 3 cm on the coating surface with red magic and black magic, and after 6 hours, wipe off with absorbent cotton soaked with isopropyl alcohol.
The surface of the coating film was observed.

(4) Adhesion: Based on JIS-K5400 cross cut test. (5) Scratch resistance testing machine: Gakushin type friction fastness tester manufactured by Tester Sangyo Co., Ltd. Test load: 500 g Reciprocating speed: Approx. 30 times / min Specimen mounting base: Surface R 200 mm Reciprocating distance: Approx. 120 mm Friction element contact Area: about 1 cm ² Test method: A test piece cut into a strip shape is mounted on a test piece mounting table. Further, steel wool (Bonstar # 0000) is attached to the surface of the friction element. A friction test was performed 200 times in a room at an atmosphere temperature of 25 ° C., and the degree of damage on the coating film surface was visually observed. Table 2 shows the results.

[0036]

[Table 2]

[0037]

The photocurable resin composition of the present invention and a paint using the same have excellent smoothness of a coating film when applied to a plastic substrate or the like, and have excellent adhesion to an isocyanate-cured acrylic polyol coating film. Excellent, excellent scratch resistance of the coating film, and excellent flexibility of the coating film. In addition, according to the method for producing a cured coating film of the present invention, when applied to a plastic substrate or the like, the coating film has excellent smoothness, excellent adhesion to an isocyanate-cured acrylic polyol coating film, and abrasion resistance of the coating film. And a coating film excellent in flexibility of the coating film is obtained.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shuichi Kondo Fifth terminator at Kashima Plant, Hashima-cho, Kashima-gun, Kashima-gun, Ibaraki Pref. SA02 SA16 SA17 SA20 SA22 SA25 SA27 SA28 SA32 SA34 SA42 SA54 SA61 SA63 SA64 SA76 SA78 SA79 SA83 UA01 UA03 VA01 WA02 4J027 AA02 AC01 AC03 AC04 AC06 AG01 AG08 AG23 AG24 AG25 AG28 BA07 BA08 BA09 BA10 BA12 BA13 BA15 BA19 BA20 BA05 CD26 4J038 FA012 FA152 FA162 FA172 FA212 FA281 GA03 GA11 JA33 JA34 JA66 JB08 JB16 JC02 KA03 NA11 NA12 PA17 PB02 PB09

Claims (8)

[Claims] 1. A urethane compound (A) having at least two structures having at least two unsaturated double bonds via a urethane bond in one molecule, represented by the general formula (I): (Wherein, R represents a hydrogen atom or a methyl group) A photocurable resin composition comprising a photopolymerizable monomer (B) represented by the following formula and a photopolymerization initiator (C). 2. The photocurable resin composition according to claim 1, further comprising a photopolymerizable monomer (D) having an unsaturated double bond. 3. An isocyanate compound (a) in which the component (A) has three isocyanate groups and a hydroxyl group-containing unsaturated compound having two or more unsaturated double bonds and one hydroxyl group in one molecule ( The photocurable resin composition according to claim 1 or 2, which is obtained by reacting b). 4. The isocyanate compound (a) is a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate, a trimer of trimethylhexamethylene diisocyanate or a trimer of hexanemethylene diisocyanate. Photocurable resin composition. 5. A hydroxyl group-containing unsaturated compound (b)
Is a pentaerythritol triacrylate, a diacrylate of trihydroxyethyl isocyanurate, a pentaerythritol trimethacrylate or a dimethacrylate of trihydroxyethyl isocyanurate. 6. Component (D) is polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triacrylate of trihydroxyethyl isocyanurate, polypropylene glycol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate or The photocurable resin composition according to claim 2, which is a trimethacrylate of trihydroxyethyl isocyanurate. 7. A paint containing the photocurable resin composition according to claim 1. 8. A method for producing a cured coating film, comprising applying the coating material according to claim 7 on a substrate on which a coating film of an isocyanate-cured acrylic polyol resin is formed, and curing.