JP6996199B2 - Urethane paint composition and molded product - Google Patents

Description

The present invention relates to a urethane coating composition and a molded body having a coating film of the urethane coating composition.

Synthetic resins such as acrylic resin, polycarbonate resin, polystyrene resin and ABS resin are used in various fields because they are easy to mold. However, since the molded product made of these resins is inferior in scratch resistance and abrasion resistance on the surface thereof as compared with glass and the like, the appearance and function are easily impaired by scratches and dents. In order to solve these problems, a method of covering the surface of a resin molded product with a coating film having excellent scratch resistance to protect it has been generally performed, and various paints having such a function have been proposed.

For example, Patent Document 1 describes a urethane resin paint using silica fine particles as a reinforcing material in an acrylic polyol and a polyisocyanate, and a molded body having a coating film thereof. Further, Patent Document 2 describes a urethane resin paint using silica fine particles as a reinforcing material in cellulose acetate butyrate and polyisocyanate, and a molded product having a coating film thereof.

Japanese Unexamined Patent Publication No. 2012-21111 Japanese Unexamined Patent Publication No. 2013-142119

Patent Document 1 and Patent Document 2 describe a urethane resin coating composition containing silica particles in order to improve the abrasion resistance of the coating film. However, the urethane resin coating composition described in the above patent document has insufficient scratch resistance and wear resistance under conditions of long-term outdoor use. In particular, in order to prevent deterioration of appearance such as whitening due to aggregation of silica particles, scratch resistance and wear resistance when the amount of silica particles is reduced are insufficient.

The present invention aims to solve these problems, and has various performances such as scratch resistance and abrasion resistance of the coating film even under conditions of long-term outdoor use such as vehicle exterior parts. It is an object of the present invention to provide a urethane coating composition capable of maintaining the above-mentioned properties and a molded product having a coating film of the urethane coating composition.

That is, the above-mentioned problem of the present invention can be solved by the following means [1] to [8].
[1] A urethane coating composition containing a polyol (A), a polyisocyanate (B), and reactive silica particles (C), wherein the polyol (A) has a mass average molecular weight of 100 or more and 800 or less. A urethane coating composition in which the reactive silica particles (C) have a functional group capable of reacting with a hydroxyl group or an isocyanate group on the surface.
[2] The urethane coating composition according to the above [1], wherein the polyol (A) is polycaprolactone triol.
[3] The urethane coating composition according to the above [1] or [2], wherein the polyisocyanate (B) is a trifunctional or higher functional isocyanate compound.
[4] Any of the above [1] to [3], wherein the functional group capable of reacting with the hydroxyl group or isocyanate group on the surface of the reactive silica particles (C) is any of a mercapto group, an isocyanate group or an epoxy group. The urethane coating composition according to item 1.
[5] The urethane coating composition according to any one of the above [1] to [4], which comprises an acrylic polyol (D) having a mass average molecular weight of 5,000 to 200,000.
[6] The urethane coating composition according to any one of the above [1] to [5], which comprises cellulose acetate butyrate (E) having a number average molecular weight of 10,000 to 100,000.
[7] A molded product having a coating film of the urethane coating composition according to any one of the above [1] to [6].
[8] The molded body according to the above [7], wherein the molded body is a vehicle exterior product.

The urethane coating composition of the present invention can maintain the scratch resistance, abrasion resistance, chemical resistance and other performance of the coating film even under conditions of long-term outdoor use such as vehicle exterior parts. And a molded body having a coating film of the urethane coating composition can be provided.

The urethane coating composition of the present invention contains a polyol (A), a polyisocyanate (B), and reactive silica particles (C).
<polypoly (A)>

The mass average molecular weight of the polyol (A) in the urethane coating composition of the present invention is 100 or more and 800 or less. When the mass average molecular weight is 100 or more, the flexibility of the coating film is good. Further, when the mass average molecular weight is 800 or less, the scratch resistance and abrasion resistance of the coating film are good.
The mass average molecular weight is preferably 300 to 550.

The mass average molecular weight can be measured by the following measuring method as a polystyrene-equivalent molecular weight by the Gel Permeation Chromatography method.

(GPC measurement conditions)
Columns: "TSK-gel superHZM-M", "TSK-gel HZM-M", "TSK-gel HZ2000"
Eluent: THF
Flow rate: 0.35 mL / min
Injection volume: 10 μL
Column temperature: 40 ° C
Detector: UV-8020

The content of the polyol (A) in the coating composition of the present invention is preferably 0.5 to 40% by mass in the components forming the coating film. When the content of the polyol (A) is 0.5% by mass or more, the scratch resistance is improved. Further, when the content of the polyol (A) is 40% by mass or less, sufficient adhesion can be obtained and cracks in the coating film are less likely to occur.

The hydroxyl value of the polyol (A) is preferably 300 to 550 mg · KOH / g. When the hydroxyl value is 300 mg · KOH / g or more, a preferable crosslink density as a coating film is obtained, and scratch resistance, abrasion resistance and solvent resistance are good. Further, when the hydroxyl value is 550 mg · KOH / g or less, the solubility in the coating composition and the flexibility of the coating film when formed into a coating film are good.

Specific examples of the polyol (A) in the present invention include 1,6-hexanediol, cyclohexyldimethanol, neopentyl glycol, butylethylpropanediol, trimethylolethane, trimethylolpropane, polycaprolactone triol, and ditrimethylolpropane. , Pentaerythritol, polycaprolactone tetraol, dipentaerythritol, sorbitol, mannitol and the like. These may be used alone or in combination of two or more.

Examples of the polycaprolactone triol include Polyol 3940 and R3600 manufactured by Perstop, and Praxel 303, Praxel 305 and Praxel 308 manufactured by Daicel Chemical Co., Ltd. Examples of polycaprolactone tetraol include Polyol 4525 and Polyol 4800 manufactured by Polyester.

As the polyol (A) in the present invention, Pluxel 303, Pluxel 305, Polyol 4525, and Polyol 4800 are preferable from the viewpoint of scratch resistance and substrate adhesion.

<Polyisocyanate (B)>
The content of the polyisocyanate (B) in the coating composition of the present invention is preferably 5 to 65% by mass in the components forming the coating film. Within the above range, the weather resistance and stain resistance of the coating film can be improved.

The polyisocyanate (B) is preferably a bifunctional or higher functional isocyanate compound. As the isocyanate compound, a known compound can be used. Examples of the bifunctional isocyanate compound include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, and 4,4-dicyclohexyldiisocyanate.
Examples of the trifunctional or higher functional isocyanate compound are those synthesized from the diisocyanate compound as a starting material, and examples thereof include a bullet form, a trimethylolpropane adduct form, an isocyanurate form, and an allophanate form. From the viewpoint of increasing the crosslink density of the coating film and improving the weather resistance and stain resistance of the coating film, a trifunctional or higher functional isocyanate compound is preferable.

Examples of the trifunctional or higher functional isocyanate compound include hexamethylene diisocyanate burette body: Duranate 24A-100, hexamethylene diisocyanate adduct body: Duranate P-301-75E, and hexamethylene diisocyanate isocyanurate body: Duranate TPA. -100, Block type isocyanate body: Duranate MF-K60X, Trimethylol propane adduct body of 1,3-bis (isocyanatomethyl) cyclohexane manufactured by Mitsui Chemicals Co., Ltd .: Takenate D-120N, 1,3-bis (isocyanato) Examples thereof include isocyanurates of methyl) cyclohexane: Takenate D-127N, trimethylolpropane adducts of isophorone diisocyanate: Takenate D-140N, and allophanates of hexamethylene diisocyanate manufactured by Sumika Bayer Urethane Co., Ltd .: Death Module XP2679. These isocyanate compounds may be used alone or in combination of two or more.

<Reactive silica particles (C)>
The reactive silica particles (C) in the urethane coating composition of the present invention have a functional group capable of reacting with a hydroxyl group or an isocyanate group on the surface.

Examples of the functional group capable of reacting with the hydroxyl group or the isocyanate group include a mercapto group, an isocyanate group, an epoxy group, a hydroxyl group, an amino group and a carbamoyl group, and the mercapto group, the isocyanate group and the epoxy group have high reactivity with the hydroxyl group or the isocyanate group. Preferred in terms of points.

Examples of the reactive silica particles (C) include 2- (3,4-epylcyclohexyl) ethyltrimethoxysilane: KBM-303 and 3-glycidoxypropylmethyldimethoxysilane manufactured by Shin-Etsu Chemical Industry Co., Ltd. KBM-402, 3-glycidoxypropyltrimethoxysilane: KBM-403, 3-glycidoxypropylmethyldiethoxysilane: KBE-402, 3-glycidoxypropyltriethoxysilane: KBE-403, bis (2) -Hydroxyethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane: KBM-903, 3-aminopropyltriethoxysilane: KBE-903, N-2- (aminoethyl) -3-aminopropyl Methyldimethoxysilane: KBM-602, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane: KBM-603, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine: KBE -9103, N-phenyl-3-aminopropyltrimethoxysilane: KBM-573, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride: KBM-575, 3-mercaptopropylmethyl Dimethoxysilane: KBM-802, 3-mercaptopropyltrimethoxysilane: KBM-803, 3-isocyanuppropyltriethoxysilane: KBE-9007 and 3-ureidopropyltrialkoxysilane: KBE-585, manufactured by CIK Nanotech Co., Ltd. Examples thereof include SIRMEK20WT% -M70, SIRMEK50WT% -E86, SIRMIBK15WT% -M96, SIRMIBK30WT% -S39, MEK-EC-2130Y, MEK-EC-6150P, MEK-EC-7150P manufactured by Nissan Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

The reactive silica particles (C) in the present invention include SIRMEK20WT% -M70, SIRMEK50WT% -E86, MEK-EC-2130Y, MEK-EC-6150P, and MEK-EC-7150P from the viewpoint of compatibility with the resin. Is preferable.

The content of the reactive silica particles (C) is preferably 3 to 70% by mass in the components forming the coating film. When the content of the reactive silica particles (C) is 3% by mass or more, the abrasion resistance of the coating film can be improved. Further, if it is 70% by mass or less, cracks in the coating film can be suppressed.

In the present invention, it is possible to obtain a coating film having good scratch resistance and wear resistance even when the amount of the reactive silica particles (C) is small.

Further, the average particle size of the reactive silica particles (C) of the present invention is preferably 500 nm or less, more preferably 100 nm or less, still more preferably 50 nm or less from the viewpoint of transparency of the cured film. .. The average particle size of the silica particles can be measured as a value converted from the specific surface area measurement value (according to JIS Z8830) by the BET adsorption method.

The reactive silica particles (C) are, for example, surface-treated with a silane coupling agent having a functional group capable of reacting with a hydroxyl group or an isocyanate group on the surface of the silica particles having no functional group capable of reacting with a hydroxyl group or an isocyanate group. Obtained by doing.

Examples of the non-reactive silica having no functional group capable of reacting with a hydroxyl group or an isocyanate group on the surface include colloidal silica. Here, colloidal silica means a substance in which ultrafine particles of silicic acid anhydride are dispersed in an appropriate liquid solvent. Colloidal silica can be used in a form dispersed in water or a form dispersed in an organic solvent. From the viewpoint that the silane coupling agent can be uniformly dispersed, colloidal silica is preferably used in the form of being dispersed in an organic solvent.

Examples of the non-reactive silica include dimethylacetamide-dispersed silica sol (DMAC-ST, DMAC-ST-L) and methyl ethyl ketone-dispersed silica sol (MEK-ST, MEK-ST-L, MEK-) manufactured by Nissan Chemical Industry Co., Ltd. Examples thereof include ST-ZL, MEK-ST-UP), methyl isobutyl ketone dispersed silica sol (MIBK-ST), propylene glycol monomethyl ether acetate dispersed silica sol (PMA-ST), ethyl acetate dispersed silica sol (EAC-ST) and the like. These may be used alone or in combination of two or more.

<Acrylic polyol (D)>
Further, the urethane coating composition of the present invention preferably contains an acrylic polyol (D) having a mass average molecular weight of 5,000 to 200,000. The mass average molecular weight is preferably 5,000 or more in terms of good flexibility to the coating film, sufficient compatibility with the coating composition can be obtained, and whitening of the coating film is less likely to occur during film formation. It is preferably 200,000 or less.

The content of the acrylic polyol (D) is preferably 0.5 to 70% by mass in the components forming the coating film. When the content of the acrylic polyol (D) is 0.5% by mass or more, the scratch resistance is improved. Further, if it is 70% by mass or less, sufficient adhesion can be obtained and cracks in the coating film are less likely to occur.

The acrylic polyol (D) comprises, for example, a polymerizable unsaturated monomer having one or more active hydrogens in one molecule and another radically polymerizable unsaturated monomer copolymerizable therewith. It can be obtained by copolymerizing.

6-Hexanolide addition polymerization of 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and -2-hydroxyethyl methacrylate as polymerizable unsaturated monomers having one or more active hydrogens in one molecule. Substance (polymerization degree 1 to 6), hydroxyl group-containing (meth) acrylic monomer such as glyceryl (meth) acrylate, glyceryl-1-methacryloyloxyethyl urethane, α, 1-ethylenically unsaturated carboxylic acid: for example, acrylic acid, Glydisyl group-containing vinyl-based monomers such as methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride and fumaric acid: for example, glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether, acrylic acid or methacrylic acid amide: For example, acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide and the like can be mentioned.

2-Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, acrylic acid, and methacrylic acid are preferable from the viewpoint of improving the scratch resistance and abrasion resistance of the coating film.

As another radically polymerizable unsaturated monomer copolymerizable with the polymerizable unsaturated monomer having one or more active hydrogens in one molecule, an ester of acrylic acid or methacrylic acid: for example, (meth). Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic C1-18 alkyl or cycloalkyl ester of acrylic acid or methacrylic acid such as lauryl acid, cyclohexyl (meth) acrylate, octyl methacrylate, lauryl methacrylate and cyclohexyl methacrylate; methoxybutyl (meth) acrylate, (meth) acrylic. Acrylic acid or alkoxyalkyl ester of acrylic acid such as methoxyethyl (meth) acrylate; glycidyl acrylate or glycidyl methacrylate and a C3-18 monocarboxylic acid compound (eg acetic acid, propionic acid, oleic acid, stearic acid or An ethylenically unsaturated monomer having an alkoxysilane group, such as an adduct with (lauric acid), an adduct of Cardula E-10 and an unsaturated acid such as acrylic acid: for example, 1-methacryloxytrimethoxysilane, etc .: Examples thereof include acrylonitrile and methacrylonitrile.

Methyl (meth) acrylate, ethyl (meth) acrylate, and cyclohexyl (meth) acrylate are preferable because the coating film has good scratch resistance and abrasion resistance.

<Cellulose Acetate Butyrate (E)>
Further, the urethane coating composition of the present invention preferably contains cellulose acetate butyrate (E) having a number average molecular weight of 10,000 to 100,000.

The number average molecular weight is preferably 10,000 or more in terms of improving the flexibility of the coating film when it is dissolved in the coating composition to form a coating film. Further, 100,000 or less is preferable in that the required cross-linking density as a coating film can be obtained and the scratch resistance and abrasion resistance are good.

The number average molecular weight can be measured as a polystyrene-equivalent molecular weight by the Gel Permeation Chromatography method by the same measuring method as the mass average molecular weight measuring method.

The content of the cellulose acetate butyrate (E) is preferably 0.5 to 40% by mass in the components forming the coating film. When the content of the cellulose acetate butyrate is 0.5% by mass or more, the scratch resistance is improved. Further, when the content of the cellulose acetate butyrate is 40% by mass or less, sufficient adhesion can be obtained and cracks in the coating film are less likely to occur.

Examples of the cellulose acetate butyrate include CAB-551-0.01, CAB-551-0.2, CAB-553-0.4, CAB-531-1, and CAB-500- manufactured by Eastman Chemical Company. 5, CAB-321-0.1, CAB-381-0.1, CAB-381-0.5, CAB-381-2, CAB-321-20 and the like can be mentioned. These may be used alone or in combination of two or more.

The cellulose acetate butyrate is preferably CAB-500-5, CAB-381-0.1, CAB-381-0.5, CAB- from the viewpoint of imparting solvent resistance and scratch resistance to the coating film. 381-2.

The cellulose acetate butyrate preferably has a hydroxyl value of 1 to 200 mgKOH / g. Cellulose acetate butyrate having a hydroxyl value of 1 mgKOH / g or more has a high crosslink density in the coating film and has good solvent resistance and the like. Further, cellulose acetate butyrate having a hydroxyl value of 200 mgKOH / g or less has good extensibility of the coating film. The hydroxyl value is a theoretical value or a value measured according to 6.4 of JISK-1557.

Further, the cellulose acetate butyrate has a degree of acetylation of 1 to 34% by mass, a degree of butyrylization of 16 to 60% by mass, and ASTM- It is preferable that the viscosity according to the measurement method described in D-1343 is in the range of 0.0005 to 2 Pa · s.

In the present invention, the coating film-forming component corresponds to the above-mentioned polyol (A), polyisocyanate (B), reactive silica particles (C), acrylic polyol (D) and cellulose acetate butyrate (E). It means everything.

<Ultraviolet absorber (F)>
Further, the urethane coating composition of the present invention preferably contains an ultraviolet absorber (F). The ultraviolet absorber improves the weather resistance of the formed coating film and prevents deterioration of the surface of the molded product.

The content of the ultraviolet absorber (F) is preferably 1 to 10% by mass with respect to 100% by mass of the components forming the coating film. When the content of the ultraviolet absorber is 1% by mass or more, the effect of improving the weather resistance to the coating film is obtained, and when it is 10% by mass or less, the adhesion and scratch resistance of the coating film are not deteriorated.

Examples of the ultraviolet absorber (F) include salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, hydroxyphenyltriazine-based compounds, and the like.

Examples of the salicylate compound include phenyl salicylate, p-tert. -Butylphenyl salicylate, p- (1,1,3,3, -tetramethylbutyl) phenylsalicylate, 3-hydroxyphenylbenzoate, phenylene-1,3-dibenzoate and the like can be mentioned.

Examples of benzophenone compounds include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyroxybenzophenone, and 4-dodecyloxy-. Examples thereof include 2-hydroxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

Examples of the benzotriazole-based compound include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, and 2- (2-hydroxy-5-tert.-butyl). Phenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert.-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert.-butylphenyl) benzotriazole and 2 -(2-Hydroxy-4-octyroxyphenyl) benzotriazole and the like can be mentioned.

Examples of the hydroxyphenyltriazine compound include 2,4-bis (2-hydroxy-4-butyloxyphenyl) -6- (2,4-bis-butyloxyphenyl) -1,3,5-triazine and 2-[. 4 [(2-Hydroxy-3- (2'-ethyl) hexyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethoxyphenyl) -1,3,5-triazine and 2- (2-Hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine and the like can be mentioned.

These UV absorbers may be used alone or in combination of two or more.

In particular, those having good compatibility with the components forming the coating film and having a large absorption coefficient in the ultraviolet region are preferable from the viewpoint of preventing deterioration in the weather resistance of the coating film and the resin molded product. Examples of such an ultraviolet absorber include 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine. Can be mentioned.

Examples of the ultraviolet absorber (F) include TINUVIN-PS, TINUVIN99-2, TINUVIN109, TINUVIN328, TINUVIN384-2, TINUVIN900, TINUVIN928, TINUVIN1130 (hereinafter, benzotriazole type), TINUVIN400, TINUVIN405, TINUVIN4, manufactured by BASF. , TINUVIN477, TINUVIN479 (above, hydroxyphenyltriazine type) and the like.

In particular, those having good compatibility with the coating film forming components (a) to (e) include TINUVIN99-2, TINUVIN384-2, TINUVIN900, TINUVIN928, TINUVIN1130, TINUVIN400, TINUVIN477, TINUVIN479 and the like.

<Organic solvent>
Further, the urethane coating composition of the present invention can be diluted with an organic solvent for the purpose of preparing the solid content of the coating composition. Examples of the organic solvent include alcohol-based, carboxylic acid ester-based, ketone-based, amide-based, aliphatic and aromatic hydrocarbon-based solvents.

For example, examples of the alcohol solvent include methanol, isopropyl alcohol, n-butanol, diacetone alcohol, 2-methoxyethanol (methylcellosolve), 2-ethoxyethanol (ethylcellosolve), 2-butoxyethanol (butylcellosolve) and tertiary amyl. Alcohol and the like can be mentioned.

Examples of the carboxylic acid ester solvent include ethyl acetate, n-propyl acetate, butyl acetate and butyl formate; and examples of the ketone solvent include methyl ethyl ketone and methyl isobutyl ketone. Examples of the amide-based solvent include dimethylformamide and dimethylacetamide. Examples of the aliphatic and aromatic hydrocarbon solvents include hexane, pentane xylene, toluene and benzene.

These organic solvents may be used alone or in combination of two or more. Of these organic solvents, carboxylic acid ester-based and ketone-based solvents such as ethyl acetate, butyl acetate, methyl ethyl ketone, and methyl isobutyl ketone are the main components, and a solvent obtained by mixing these with a polar solvent such as alcohol is soluble. It is preferable from the viewpoint of volatileness and adhesion.

<Curing accelerator>
In the urethane coating composition of the present invention, a curing acceleration catalyst that promotes curing of the polyisocyanate and the polyol can be added. The content of the curing acceleration catalyst is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and 0.1 to 1 part by mass with respect to 100 parts by mass of the polyisocyanate. It is more preferably by mass.

Examples of the curing acceleration catalyst include triethylamine, tetra (2-ethylhexyl) titanate, di-n-butyltin dilauric acid, 1,4-diazabicyclo [2.2.2] octane and the like. These curing acceleration catalysts may be used alone or in combination of two or more.

Further, the urethane coating composition of the present invention can be used as an antioxidant, a defoaming agent, a leveling agent, a rheology control agent, a viscosity modifier, a matting agent, a light stabilizer (for example, a hindered amine compound, etc.), and a dye. And pigments and the like may be contained within a range that does not impair the action and effect of the present invention.

Next, an example of the method for producing the urethane coating composition of the present invention will be shown.
The urethane coating composition of the present invention is, for example, a mixture of polyol (A), polyisocyanate (B) and reactive silica particles (C), and if necessary, acrylic polyol (D), cellulose acetate butyrate (E), ultraviolet rays. It can be produced by mixing an absorbent (F), an organic solvent, a curing acceleration catalyst and the like. The mixing order of each component is not particularly limited, but it is preferable to mix the reactive silica particles (C) dispersed in the organic solvent as later as possible in that all the components can be mixed uniformly. Further, in terms of improving the dispersibility in the urethane coating composition of the present invention, it is preferable that the ultraviolet absorber (F) and the curing acceleration catalyst are each dissolved in an organic solvent in advance and then mixed.

<Molded body with a coating film of urethane paint composition>
The coating composition of the present invention can modify the surface of a resin molded product by coating the surface of the resin molded product as a base material and curing the coating composition. A known resin can be used as the resin molded product. Specific examples thereof include polymethylmethacrylate resin, polycarbonate resin, polystyrene resin, acrylonitrile / styrene copolymer resin, polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, polyamide resin and the like. Among these, the polycarbonate resin in particular has low weather resistance and is liable to cause discoloration, deterioration, deterioration, etc. when used outdoors, so that the effect of the present invention can be maximized.

The method for coating the surface of the resin molded body of the coating composition of the present invention is not particularly limited, and known methods such as brush coating, sink coating, dip coating, spray coating and spin coating can be adopted. ..

The film thickness of the coating film obtained by curing the coating composition of the present invention is preferably 1 to 30 μm. When the film thickness of the coating film is 1 μm or more, the effect of preventing surface deterioration of the resin molded product as the base material can be enhanced. Further, if the thickness is 30 μm or less, the adhesion to the substrate can be improved and cracks can be reduced.

As a means for curing the coating composition of the present invention, heat treatment can be mentioned. The heat treatment temperature is preferably room temperature or higher and 200 ° C. or lower, and more preferably 40 ° C. or higher and 150 ° C. or lower. The heat treatment temperature may be appropriately adjusted according to the heat resistance, thermal deformability, etc. of the resin molded product to be used. The heating time varies depending on the heating temperature, but is usually about several minutes to several hours.

The coating film made of the urethane coating composition of the present invention can maintain various performances such as scratch resistance and abrasion resistance of the coating film even when used outdoors for a long time, and is suitable for use in vehicle exterior products. Can be used for.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In Examples and Comparative Examples, "%" indicates mass% unless otherwise specified. Each component used in each Example and Comparative Example is as follows.

<polypoly (A)>
a-1; Polycaprolactone triol (Plaxel 303, manufactured by Daicel Corporation, solid content 100% by mass, mass average molecular weight 300, hydroxyl value 530 to 550 mg, KOH / g)
a-2; Polycaprolactone triol (Plaxel 305, manufactured by Daicel Corporation, solid content 100% by mass, mass average molecular weight 550, hydroxyl value 300-310 mg · KOH / g)
a-3; Polycaprolactone triol (Plaxel 308, manufactured by Daicel Corporation, solid content 100% by mass, mass average molecular weight 850, hydroxyl value 190-200 mg · KOH / g)
a-4; Glycerin (solid content 100% by mass, number of hydroxyl groups 3, molecular weight 92, hydroxyl value 1,830 mg, KOH / g)

<Polyisocyanate (B)>
b-1; Isocyanurate form of hexamethylene diisocyanate (Duranate TPA-100, manufactured by Asahi Kasei Corporation, solid content 100% by mass)

<Reactive silica particles (C)>
c-1; 5.3 g of 3-mercaptopropyltrimethoxysilane (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) and 5.0 g of fumed silica heated at 110 ° C. under reduced pressure for 16 hours were added to 83 g of toluene and suspended. The mixture was turbid and heated to reflux for 24 hours to obtain mercapto group-containing colloidal silica (solid content: 11% by mass).
c-2; Isocyanate group-containing colloidal silica (SIRMEK20WT% -M70, manufactured by CIK Nanotech Co., Ltd., solid content 19% by mass)
c-3; A cooling tube and a stirrer were attached to a three-necked eggplant-shaped flask, and MIBK-ST 100.0 g and 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) 70. 8 g of the mixture was charged and the temperature was raised to 70 ° C. The reaction was carried out for 5 hours to obtain an epoxy group-containing colloidal silica dispersion (solid content 59% by mass).

<Non-reactive silica particles>
c-4; MIBK-ST (manufactured by Nissan Chemical Industries, Ltd., solid content 30% by mass)

<Acrylic polyol (D)>
d-1; A cooling tube and a stirrer were attached to a three-necked eggplant-shaped flask, and methyl isobutyl ketone (MIBK) 78.4 g, hydroxyethyl methacrylate 5.0 g (38 mmol), cyclohexyl methacrylate 79.7 g (474 mmol) and polymerization were performed. A mixture of 4.8 g of an initiator (Perhexyl PV manufactured by NOF Corporation, solid content 70%) was charged, and the temperature was raised to 65 ° C. while stirring in a nitrogen atmosphere, and the reaction was carried out for 5 hours. Further, the temperature was raised to 85 ° C., and after reacting for 1 hour and 30 minutes, the mixture was cooled to room temperature to obtain an acrylic resin (solid content 53%, mass average molecular weight (Mw) 20000, hydroxyl value 25 mg · KOH / g). ..
<Cellulose Acetate Butyrate (E)>
e-1: Cellulose acetate butyrate (trade name: CAB-381-0.5, manufactured by Eastman, solid content 15%, number average molecular weight 30,000, hydroxyl value 42.9 mg / KOH / g, butyl acetate solution)

<Ultraviolet absorber (F)>
f-1; 2- [4-[(2-Hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5 -Triazine (trade name: TINUVIN400, manufactured by BASF)

(Examples 1 to 8 and Comparative Examples 1 to 4)
The components (a) to (f) are blended in the proportions shown in Tables 1 and 2, and 0.06 g of di-n-butyltin dilauryrate (solid content of the reactive silica particles (C)) as an additive is further added. 0.6% by mass), 0.5 g of a light stabilizer (trade name: TINUVIN123, manufactured by BASF), and 0.3 g of a leveling agent (trade name: BYK375, manufactured by Big Chemie) were added to Example 1. The coating compositions of No. 8 and Comparative Examples 1 to 4 were prepared. Each paint composition is placed on a polycarbonate resin injection molded plate (trade name: Panlite L-1225Z-100, clear, thickness 3 mm, manufactured by Teijin Chemicals Ltd.) so that the film thickness after curing is 10 μm. It was applied using a bar coater and heat-cured in an oven set at 115 ° C. for 20 minutes. The prepared test piece was left at room temperature for 9 days, and evaluated by the following test methods (1) and (2). The evaluation results are shown in Tables 1 and 2.

1. 1. Scratch resistance test; Scratch resistance was evaluated by the following procedure.
(1) The diffusion transmittance (haze value) of the coating film of the test piece before the test is measured with a haze meter (HM-65W, manufactured by Murakami Color Technology Laboratory Co., Ltd.).
(2) The coated surface of the test piece is rubbed 11 times with steel wool (# 000) carrying a load of 13.7 kg.
(3) The diffusion transmittance (haze value) of the test piece after the test is measured with the haze meter.
(4) The scratch resistance is evaluated by the Δ haze value (post-test haze value-pre-test haze value).
(Evaluation criteria)
◯: A Δ haze value of less than 10 was regarded as good scratch resistance.
X: A scratch resistance defect was defined as a Δ haze value of 10 or more.

2. 2. Abrasion resistance test; Scratch resistance was evaluated by the following procedure.
(1) The diffusion transmittance (haze value) of the coating film of the test piece before the test is measured with a haze meter (HM-65W, manufactured by Murakami Color Technology Laboratory Co., Ltd.).
(2) The coated surface of the test piece is worn 500 times with a wear wheel CS-10F having a load of 500 g.
(3) The diffusion transmittance (haze value) of the test piece after the test is measured with the haze meter.
(4) The wear resistance is evaluated by the Δ haze value (post-test haze value-pre-test haze value).
(Evaluation criteria)
◯: A wear resistance of less than 10 was considered to be good.
X: A wear resistance defect was defined as a Δhaze value of 10 or more.

The evaluation results are shown in Tables 1 and 2. In Comparative Example 1, since the reactive silica particles (C) were not used, the scratch resistance and abrasion resistance of the coating film were insufficient. Further, in Comparative Example 2 and Comparative Example 3, since the mass average molecular weight of the polyol (A) is out of the range specified in the present invention, the abrasion resistance of the coating film in Comparative Example 2 is insufficient, and Comparative Example 3 Was inadequate in scratch resistance and abrasion resistance. Further, in Comparative Example 4, the coating film did not cure because it did not contain the polyisocyanate (B).

Claims (6)

A urethane coating composition containing a polyol (A), a polyisocyanate (B) , reactive silica particles (C) and a cellulose acetate butyrate (E) , wherein the polyol (A) has a mass average molecular weight of 100 or more and 800. The reactive silica particles (C) have at least one functional group selected from the group consisting of a mercapto group, an isocyanate group and an epoxy group capable of reacting with a hydroxyl group or an isocyanate group on the surface thereof . A urethane coating composition having a number average molecular weight of cellulose acetate butyrate (E) of 10,000 to 100,000 . The urethane coating composition according to claim 1, wherein the polyol (A) is polycaprolactone triol. The urethane coating composition according to claim 1 or 2, wherein the polyisocyanate (B) is a trifunctional or higher functional isocyanate compound. The urethane coating composition according to any one of claims 1 to 3, which comprises an acrylic polyol (D) having a mass average molecular weight of 5,000 to 200,000. A molded product having a coating film of the urethane coating composition according to any one of claims 1 to 4 . The molded product according to claim 5 , wherein the molded product is a vehicle exterior product.