JP6705295B2 - Thermosetting coating composition - Google Patents

Description

The present invention relates to a thermosetting coating composition, a cured film, and a resin member having a cured film.

Synthetic resins such as acrylic resins, polycarbonate resins, polystyrene resins, and ABS resins are easy to mold, are lightweight, and have excellent impact resistance, and are used as resin members in various fields.

However, since these resin members have inferior scratch resistance, abrasion resistance, etc. of the surface as compared with glass, etc., the surface of the resin member has a cured film (hard coat film) excellent in scratch resistance, etc. The method of covering with is generally performed (patent document 1).

As a method of coating the surface of the resin member, for example, using a thermosetting coating composition for forming a hard coat film, after coating the surface of the resin member by spraying or flow coating, in a thermosetting furnace, A method of curing (crosslinking) a non-volatile component (solid content) contained in the composition while volatilizing a volatile component such as an organic solvent contained in the composition is used.

Usually, in a urethane thermosetting coating composition for forming a urethane cured film, a dialkyltin compound such as dibutyltin dilaurate, which has a high catalytic activity for the urethanization reaction, is used as a catalyst. However, in a urethane thermosetting coating composition containing silica particles, curing (crosslinking) thereof is difficult to proceed sufficiently, and therefore it is known to use a carboxylic acid metal salt as a catalyst (Patent Document 2).

Further, it has been reported that an amine salt such as a formate salt of 1,8-diazabicyclo[5.4.0]undecene-7 is used as a catalyst in a urethane resin composition containing silica particles (Patent Document 3). Furthermore, an amine salt such as a formate salt of 1,8-diazabicyclo[5.4.0]undecene-7 as a catalyst is added to a urethane resin composition for a primer (undercoating agent for a hard coat film) containing silica particles. It is reported to be used (Patent Document 4).

JP 2012-21111 A JP, 2014-185269, A JP, 2009-242600, A JP, 2010-100472, A

However, when the carboxylic acid metal salt is used in the urethane thermosetting coating composition as in Patent Document 2, the carboxylic acid metal salt tends to be difficult to dissolve in the organic solvent contained in the composition. As described above, when the solubility in the organic solvent is low, the step of blending the thermosetting coating composition takes time, which is a problem from the viewpoint of production efficiency.

Further, Patent Documents 3 and 4 disclose a cured film formed from a urethane resin composition containing silica particles using the amine salt as described above as a catalyst, but the obtained cured film is scratch resistant. Since it is inferior in properties, it cannot be used as a hard coat film.

Further, in the thermosetting coating composition, when a resin member made of a synthetic resin is used as a substrate, the curing temperature of the composition is required to be equal to or lower than the heat distortion temperature of the synthetic resin, and the production efficiency is improved. From the viewpoint, it is desirable that the curing time is shorter.

The present invention, a urethane composition containing silica particles, while using a catalyst having good solubility in an organic solvent, to sufficiently proceed a curing (crosslinking) reaction even at a temperature below the heat distortion temperature of the synthetic resin, It is an object of the present invention to provide a thermosetting coating composition that forms a cured film having excellent scratch resistance, transparency, and adhesion.

As a result of intensive studies to solve the above problems, the present inventors have found that the thermosetting coating composition shown below can achieve the above object, and have completed the present invention.

That is, the present invention contains an acrylic polyol (a), a low molecular weight polyol (b), silica particles (c), a polyisocyanate (d), and a catalyst (e), and the low molecular weight polyol (b). Has a molecular weight of 60 to 500 and a hydroxyl value of 500 to 2,000 mg·KOH/g, and the catalyst (e) has the following general formula (1).
[In the formula, X represents an acid having a pKa of 2 to 12] and/or the following general formula (2).
[Wherein, X represents an acid having a pKa of 2 to 12], and the acrylic polyol (a) is added to the total weight of the above (a) to (d) in an amount of 0. 5 to 21% by weight, low molecular weight polyol (b) 0.5 to 17% by weight, and silica particles (c) 36 to 79% by weight, and 100 parts by weight of silica particles (c), 0.1 to 2.2 parts by weight of the catalyst (e) is contained, and the acrylic polyol (a), the low molecular weight polyol (b), and the polyisocyanate (d) are the isocyanate groups of (d)/{(a). And a total hydroxyl group of (b)} in an equivalent ratio of 0.4 to 2.4 are blended in the thermosetting coating composition.

The present invention also relates to a cured film formed from the thermosetting coating composition.

The cured film of the present invention is preferably a hard coat film.

The present invention relates to a resin member having the cured film.

In the present invention, by using the tertiary amine salt represented by the above general formula (1) and/or the general formula (2) as a catalyst, a urethane thermosetting coating composition containing silica particles can be used as a synthetic resin. The curing (crosslinking) reaction can be sufficiently promoted even under a temperature condition equal to or lower than the heat distortion temperature. In particular, even in the urethane thermosetting coating composition containing a large amount of silica particles, the curing (crosslinking) reaction can be sufficiently advanced. Further, since the tertiary amine salt represented by the general formula (1) and/or the general formula (2) has excellent solubility in an organic solvent, the time required for compounding the composition can be shortened, and the production in the compounding step can be performed. The efficiency can be increased.

Further, the cured film of the present invention has good scratch resistance, transparency, and adhesion, and is therefore useful as a hard coat film.

In a urethane thermosetting coating composition containing silica particles, a dialkyltin compound such as dibutyltin dilaurate or an amine compound is likely to be adsorbed on the surface of the silica particles, and thus it is considered that the compound does not sufficiently function as a catalyst for the urethanization reaction. On the other hand, since the tertiary amine salt represented by the general formula (1) and/or the general formula (2) used in the present invention forms a salt, it is difficult to be adsorbed on the surface of silica particles, and the salt is not heated by heating. It is considered that the dissociation causes the catalyst to function.

The thermosetting coating composition of the present invention contains an acrylic polyol (a), a low molecular weight polyol (b), silica particles (c), a polyisocyanate (d), and a catalyst (e).

<Acrylic polyol (a)>
The acrylic polyol (a) of the present invention mainly has a function of imparting flexibility to a cured film and an effect of imparting adhesion to a resin member which is a base material, and has radical polymerizable property including a hydroxyl group-containing monomer. It is a hydroxyl group-containing (meth)acrylic polymer obtained by radically polymerizing monomers.

<Hydroxyl group-containing monomer>
As the hydroxyl group-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth). ) Acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate and other hydroxyalkyl (meth)acrylates; (4-hydroxymethylcyclohexyl)methyl (meth) ) Hydroxyalkylcycloalkane (meth)acrylates such as acrylates. Further, 2-hydroxybutyl (meth)acrylate 6-hexanolide addition polymer (polymerization degree 1 to 6), glyceryl mono(meth)acrylate, glyceryl-1-(meth)acryloyloxyethyl urethane, hydroxyethyl (meth)acrylamide. , Allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like. The hydroxyl group-containing monomers can be used alone or in combination. Among these, hydroxyalkyl (meth)acrylate and hydroxyalkylcycloalkane (meth)acrylate are preferable, and 2-hydroxyethyl (meth)acrylate is more preferable.

<Alkyl (meth)acrylate having an alkyl group at the ester end>
As the radically polymerizable monomer other than the hydroxyl group-containing monomer, an alkyl (meth)acrylate having an alkyl group at the ester end should be included from the viewpoint of enhancing the flexibility of the cured film and enhancing the adhesion to the substrate. Is preferred. Examples of the alkyl group of the alkyl (meth)acrylate having an alkyl group at the ester terminal include a straight chain alkyl group, a branched chain alkyl group, and a cyclic cycloalkyl group. The alkyl (meth)acrylate having an alkyl group at the ester terminal has 1 to 18 carbon atoms in the alkyl group from the viewpoint of further increasing the flexibility of the cured film and the adhesiveness with the base material. Is preferred, 3 to 14 is preferred, and 5 to 10 is more preferred.

Examples of the alkyl(meth)acrylate having an alkyl group at the ester terminal include methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, s-butyl(meth)acrylate, t-butyl( (Meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, isohexyl (meth)acrylate, heptyl (meth)acrylate, isoheptyl (meth)acrylate , 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate , N-undecyl acrylate, isoundecyl acrylate, n-dodecyl acrylate, isododecyl acrylate, n-tridecyl acrylate, isotridecyl acrylate, n-mistyryl acrylate, isomistyryl acrylate, n-pentadecyl acrylate, isopenta Decyl acrylate, n-hexadecyl acrylate, isohexadecyl acrylate, n-heptadecyl acrylate, isoheptadecyl acrylate, n-octadecyl acrylate, isooctadecyl acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth ) Acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate and the like. The alkyl (meth)acrylates having an alkyl group at the ester end can be used alone or in combination. Among these, cycloalkane (meth)acrylate is preferable, and cyclohexyl (meth)acrylate is more preferable.

As the radical-polymerizable monomer, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethyleneglycol (meth)acrylate, propoxypolyethyleneglycol (having an oxyethylene group having an average addition mole number of 2 to 10 as another radical-polymerizable monomer Ether bond-containing monomers such as (meth)acrylate; glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3- Cyclic ether group-containing monomers such as ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyloxetanylmethyl (meth)acrylate; (meth)acrylic acid, carboxyethyl (meth)acrylate , Carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and other carboxyl group-containing monomers; (meth)acrylamide, N-methylacrylamide, N,N-dimethyl(meth)acrylamide, N -Ethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide and other acrylamide monomers; 3-(trimethoxysilyl)propyl methacrylate and the like (Meth)acrylate having an alkoxysilane group or the like can be used. Other radically polymerizable monomers can be used alone or in combination.

In the present invention, the hydroxyl group-containing monomer is preferably 10% by weight or more, and preferably 20% by weight or more, with respect to the total monomer components forming the acrylic polyol (a), from the viewpoint of increasing the crosslink density of the cured film. More preferably. From the viewpoint of increasing the flexibility of the cured film, the hydroxyl group-containing monomer is preferably 50% by weight or less, and more preferably 40% by weight or less, with respect to all the monomer components forming the acrylic polyol (a). preferable.

In the present invention, the alkyl (meth)acrylate having an alkyl group at the ester terminal is 50% by weight or more from the viewpoint of increasing the adhesion to the substrate with respect to all the monomer components forming the acrylic polyol (a). It is preferably present, and more preferably 60% by weight or more. The alkyl (meth)acrylate having an alkyl group at the ester terminal is preferably 90% by weight or less based on the total monomer components forming the acrylic polyol (a), from the viewpoint of increasing the crosslink density of the cured film. It is more preferable that the content is not more than weight %.

<Method for producing acrylic polyol (a)>
As the method for producing the acrylic polyol (a), known production methods for various radical polymerizations such as solution polymerization, radiation polymerization such as electron beam and UV, bulk polymerization and emulsion polymerization can be appropriately selected. Further, the acrylic polyol (a) may be any of a random copolymer, a block copolymer, a graft copolymer and the like.

In the radical polymerization, known polymerization initiators such as azo-based initiators, peroxide-based initiators, diazo-based initiators and redox-based initiators; chains such as mercaptan-based chain transfer agents and thioglycolic acid-based chain transfer agents Transfer agent: Anionic emulsifiers, nonionic emulsifiers, and other emulsifiers are not particularly limited and may be appropriately selected and used. The weight average molecular weight of the acrylic polyol (a) can be controlled by the amount of the polymerization initiator and the chain transfer agent used and the reaction conditions, and the amount thereof can be adjusted appropriately depending on the types.

In the solution polymerization, as the polymerization solvent, for example, alcohol-based, carboxylic acid ester-based, ketone-based, amide-based, ether-based, aliphatic and aromatic hydrocarbon-based solvents can be used. Examples of alcohol solvents include methanol, isopropyl alcohol, n-butanol, diacetone alcohol, 2-methoxyethanol (methylcellosolve), 2-ethoxyethanol (ethylcellosolve), 2-butoxyethanol (butylcellosolve), tertiary amyl. Examples thereof include alcohol and diacetone alcohol. Examples of the carboxylic acid ester-based solvent include ethyl acetate, n-propyl acetate, butyl acetate, butyl formate and the like. Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, acetone and cyclohexanone. Examples of the amide solvent include dimethylformamide and dimethylacetamide. Examples of ether solvents include diethyl ether, methoxytoluene, 1,2-dimethoxyethane, 1,2-dibutoxyethane, 1,1-dimethoxymethane, 1,1-dimethoxyethane, 1,4-dioxane, and tetrahydrofuran. Etc. Examples of the aliphatic and aromatic hydrocarbon solvents include hexane, pentane xylene, toluene and benzene. The polymerization solvents can be used alone or in combination.

As a specific example of the solution polymerization, the reaction is usually carried out under a flow of an inert gas such as nitrogen and a polymerization initiator at about 40 to 170° C. for about 4 to 10 hours.

The weight average molecular weight of the acrylic polyol (a) is preferably 5,000 or more, more preferably 10,000 or more, from the viewpoint of enhancing the flexibility of the cured film. The weight average molecular weight of the acrylic polyol (a) is preferably 200,000 or less, and more preferably 100,000 or less from the viewpoint of enhancing the compatibility with the components contained in the thermosetting coating composition. ..

The weight average molecular weight of the acrylic polyol (a) can be determined by the GPC method. The sample can be measured under the following conditions by using a sample obtained by dissolving the sample in THF to prepare a 0.3% by weight solution and filtering the solution with a 0.25 μm membrane filter.
<Measurement of weight average molecular weight (Mw)>
・Analyzer: TOSOH HLC-8320GPC
-Columns 1 and 2: TSKgel SuperMulbipore HZ-M
・Column size: 15 cm x 4.6 mmφ (all two)
・Eluent: THF
・Flow rate: 0.35 ml/min
・Detector: RI
・Column temperature: 40℃
・Standard sample: polystyrene

The hydroxyl value of the acrylic polyol (a) is preferably 1 mg·KOH/g or more, more preferably 20 mg·KOH/g or more, and 40 mg·KOH/ from the viewpoint of increasing the crosslink density of the cured film. More preferably, it is g or more. From the viewpoint of enhancing the flexibility of the cured film, the hydroxyl value of the acrylic polyol (a) is preferably 200 mg·KOH/g or less, more preferably 180 mg·KOH/g or less, and 160 mg·KOH/g. It is more preferably g or less. The hydroxyl value of the acrylic polyol (a) is a theoretical value calculated from the charged amounts of all the monomers forming the acrylic polyol (a).

<Low molecular weight polyol (b)>
The low molecular weight polyol (b) of the present invention is a compound having at least two hydroxyl groups in one molecule, has a molecular weight of 60 to 500, and a hydroxyl value of 500 to 2,000 mg·KOH/g. .. The low molecular weight polyol (b) mainly has an action of increasing the crosslink density of the cured film and improving the scratch resistance of the cured film.

The molecular weight of the low molecular weight polyol (b) is preferably 70 or more, and more preferably 80 or more, from the viewpoint of enhancing flexibility of the cured film and enhancing solubility in the thermosetting coating composition. Is more preferable, and 90 or more is further preferable. The molecular weight of the low molecular weight polyol (b) is preferably 400 or less, more preferably 300 or less, and further preferably 200 or less from the viewpoint of increasing the crosslink density of the cured film.

The hydroxyl value of the low molecular weight polyol (b) is preferably 600 mg·KOH/g or more, more preferably 700 mg·KOH/g or more, and more preferably 800 mg·KOH, from the viewpoint of increasing the crosslink density of the cured film. /G or more is more preferable. The molecular weight of the low-molecular-weight polyol (b) is preferably 1,900 mg·KOH/g or less from the viewpoint of enhancing the flexibility of the cured film and enhancing the solubility in the thermosetting coating composition, It is more preferably 1,800 mg·KOH/g or less, still more preferably 1,700 mg·KOH/g or less.

Examples of the low molecular weight polyol (b) include ethanediol, propanediol, 1,4-butanediol, 1,6-hexanediol, cyclohexyldimethanol, methylpropanediol, neopentylglycol, butylethylpropanediol and glycerin. , Trimethylolethane, trimethylolpropane, polycaprolactone triol, ditrimethylolpropane, pentaerythritol, polycaprolactone tetraol, dipentaerythritol, sorbitol, mannitol and the like. The low molecular weight polyol (b) can be used alone or in combination. Examples of commercially available products of the polycaprolactone triol include Polyol 3940 and R3600 manufactured by Perstorp, and Praxel 303 manufactured by Daicel Kagaku. Further, examples of commercial products of the polycaprolactone tetraol include Polyol 4525 and Polyol 4800 manufactured by Perstorp. In particular, cyclohexyldimethanol, glycerin, trimethylolpropane, polycaprolactone triol, and polycaprolactone tetraol are preferable.

<Silica particles (c)>
The silica particles (c) of the present invention mainly have a function of suppressing volume contraction during formation of a cured film, enhancing adhesion to a substrate, and improving scratch resistance of the cured film. The average particle size of the silica particles (c) is preferably as small as possible (fine particles) from the viewpoint of increasing the light transmittance of the cured film, and specifically, it is preferably 300 nm or less, and 100 nm or less. It is more preferable that it is present, and it is further preferable that it is 50 nm or less.

As the silica particles (c), known ones can be used without limitation, but from the viewpoint of increasing the light transmittance of the cured film and from the viewpoint of enhancing the scratch resistance of the cured film, the silica sol dispersed in an organic solvent, It is preferable to use a dispersion of silica particles (c) (colloidal silica). In the state of being dispersed in an organic solvent, the surface of the silica particles (c) is usually surface-treated in advance with various silane compounds (silane coupling agents), etc., so that the surface of the silica particles (c) is hydrophobic. Have. By using the surface-treated silica particles (c), the cured film has good chemical resistance and weather resistance.

Examples of commercially available products of the dispersion of silica particles (c) (colloidal silica) include methanol-dispersed silica sol (trade name: MA-ST) and isopropyl alcohol-dispersed silica sol (trade name: IPA-ST, manufactured by Nissan Chemical Industries, Ltd.). ), n-butanol dispersed silica sol (trade name: NBA-ST), ethylene glycol dispersed silica sol (trade name: EG-ST), xylene/butanol dispersed silica sol (trade name: XBA-ST), ethyl cellosolve dispersed silica sol (trade name). : ETC-ST), butyl cellosolve-dispersed silica sol (trade name: BTC-ST), dimethylformamide-dispersed silica sol (trade name: DBF-ST), dimethylacetamide-dispersed silica sol (trade name: DMAC-ST), methyl ethyl ketone-dispersed silica sol (trade name) : MEK-ST), methyl isobutyl ketone-dispersed silica sol (trade name: MIBK-ST), ethyl acetate-dispersed silica sol (trade name: EAC-ST) and the like.

<Polyisocyanate (d)>
The polyisocyanate (d) of the present invention is a compound having at least two or more isocyanate groups in one molecule, and by curing (crosslinking) reaction with hydroxyl groups or curing (crosslinking) reaction between isocyanate groups, It mainly has the effect of improving the crosslink density of the cured film.

As the polyisocyanate (d), known ones can be used without limitation, but it is preferable that it is at least one compound selected from the group consisting of diisocyanates and their derivatives. Examples of the diisocyanate include 1,6-hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, tolylene diisocyanate and diphenylmethane diisocyanate. , Aliphatic, cycloaliphatic, and aromatic diisocyanates. Examples of the diisocyanate derivative include 1,6-hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate. And the like. Examples thereof include burettes, adducts with trimethylolpropane, isocyanurates, and allophanates, and derivatives of aliphatic, alicyclic, and aromatic diisocyanates. From the viewpoint of increasing the crosslink density of the cured film, the polyisocyanate (d) is preferably an aliphatic, alicyclic, or aromatic diisocyanate derivative. The polyisocyanate (d) is preferably a derivative of an aliphatic or alicyclic diisocyanate from the viewpoint of enhancing the weather resistance of the cured film. The polyisocyanates (d) can be used alone or in combination. The isocyanate group may be protected with a blocking agent or the like.

Examples of commercial products of the polyisocyanate (d) include hexamethylene diisocyanate burette (trade name: duranate 24A-100) and hexamethylene diisocyanate isocyanurate (trade name: duranate TPA-, manufactured by Asahi Kasei Chemicals Corporation). 100), an allophanate body of hexamethylene diisocyanate manufactured by Sumika Bayer Urethane Co., Ltd. (trade name: Desmodur XP2679), and a trimethylolpropane adduct body of 1,3-bis(isocyanatomethyl)cyclohexane manufactured by Mitsui Chemicals, Inc. (trade name) : Takenate D-120N), 1,3-bis(isocyanatomethyl)cyclohexane isocyanurate (trade name: Takenate D-127N), isophorone diisocyanate trimethylolpropane adduct (trade name: Takenate D-140N), etc. Is mentioned. Among these, the isocyanurate body of hexamethylene diisocyanate is preferable.

<Catalyst (e)>
The catalyst (e) of the present invention has the following general formula (1):
[In the formula, X represents an acid having a pKa of 2 to 12] and/or the following general formula (2).
[In the formula, X represents an acid having a pKa of 2 to 12] and is a tertiary amine salt, and has an action of promoting a curing (crosslinking) reaction between a hydroxyl group and an isocyanate group, or between isocyanate groups.

The cation in the general formula (1) is 1,5-diazabicyclo[4.3.0]nonene-5 (referred to as DBN), and the cation in the general formula (2) is 1,8-diazabicyclo. [5.4.0] Undecene-7 (referred to as DBU). Moreover, X in the said General formula (1) and (2) shows the acid of pKa=2-12. Examples of the acid include organic acids and inorganic acids. The catalyst (e) can be used alone or in combination.

As the organic acid, for example, as a carboxylic acid, a saturated aliphatic carboxylic acid (acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, methyl ethyl acetic acid, trimethyl acetic acid, caproic acid, isocaproic acid, diethyl acetic acid, 2, 2-dimethylbutyric acid, enanthic acid, caprylic acid, pelargonic acid, 2-ethylhexanoic acid, n-undecylenic acid, lauric acid, n-tridecylenic acid, myristic acid, n-pentadecylenic acid, palmitic acid, margaric acid, stearic acid, n-nonadecylenic acid, arachidic acid, n-henicoic acid, etc.), unsaturated aliphatic carboxylic acids (acrylic acid, crotonic acid, isocrotonic acid, vinyl acetic acid, methacrylic acid, 2-pentenoic acid, 3-pentenoic acid, allyl acetic acid, Angelica acid, tiglic acid, 3-methylcrotonic acid, 2-hexenoic acid, 3-hexenoic acid, 4-hexenoic acid, 5-hexenoic acid, 2-methyl-2-pentenoic acid, 3-methyl-2-pentenoic acid, 4-methyl-2-pentenoic acid, 4-methyl-2-pentenoic acid, 4-methyl-3-pentenoic acid, 2-ethylcrotonic acid, 2-heptenoic acid, 2-octenoic acid, palmitoleic acid, oleic acid, Vaccenic acid, linoleic acid, linolenic acid, elestearic acid, arachidonic acid, etc.), saturated aliphatic dicarboxylic acids (succinic acid, glutaric acid, methylsuccinic acid, adipic acid, ethylsuccinic acid, pimelic acid, propylsuccinic acid, suberic acid, azelaine) Acid, sebacic acid, etc.), alicyclic carboxylic acid (cyclopropanecarboxylic acid, cyclobutanecarboxylic acid, cyclobutenecarboxylic acid, cyclopentanecarboxylic acid, cyclopentenecarboxylic acid, cyclohexanecarboxylic acid, cyclohexenecarboxylic acid, cycloheptanecarboxylic acid, cyclo Heptenecarboxylic acid, etc.), aromatic carboxylic acid (benzoic acid, alkyl-substituted benzoic acid (3-methylbenzoic acid, 4-methylbenzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, etc.), 4-hydroxybenzoic acid Acid, alkoxy-substituted benzoic acid (2-methoxybenzoic acid, 3-methoxybenzoic acid, 4-methoxybenzoic acid, etc.), mercaptobenzoic acid, amino-substituted benzoic acid, 2-naphthoic acid, etc.), hydroxycarboxylic acid (ascorbic acid, etc.) ) And ketocarboxylic acid (levulinic acid, etc.).

Examples of the organic acid include monoalkyl carbonic acid (such as methyl carbonic acid and ethyl carbonic acid); aromatic hydroxy compound {phenol, alkyl-substituted phenol (o-cresol, m-cresol, p-cresol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, xylenol, trimethylphenol, tetramethylphenol, pentamethylphenol, etc., alkoxy-substituted phenol (2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2-ethoxyphenol, 3 -Ethoxyphenol, 4-ethoxyphenol, etc.), halogen-substituted phenol (fluorophenol, chlorophenol, bromophenol, iodophenol, etc.), naphthol, aminophenol, nitrophenol, polyhydric phenol (catechol, resorcinol, hydroquinone, biphenol, bisphenol) , Pyrogallol, phloroglucinol, hexahydroxybenzene, etc.), and thiophenol.

Examples of the inorganic acid include carbonic acid and boric acid.

The acid is preferably an organic acid from the viewpoint of high solubility in the thermosetting coating composition, and as the organic acid, saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, and aromatic hydroxy compounds are preferable. The acid preferably has a pKa of 3 or more, preferably 10 or less, and more preferably 6 or less.

Commercially available products of the catalyst (e) include DBU-formate (trade name: U-CAT SA603), DBU-octylate (trade name: U-CAT SA102), and DBU-oleate manufactured by San-Apro. (Trade name: U-CAT SA106), DBU-phenol salt (U-CAT SA1), DBN-octylate salt (trade name: U-CAT SA1102) and the like. Among these, DBU-formate, DBU-octylate, DBU-oleate and DBN-octylate are preferable.

Below, in the thermosetting coating composition of this invention, the content of the said components (a)-(e), the compounding quantity, or the usage-amount is demonstrated.

The content of the acrylic polyol (a) is 0.5 to 21% by weight based on the total weight of the components (a) to (d). The content of the acrylic polyol (a) is preferably 2% by weight or more, and preferably 4% by weight, based on the total weight of the components (a) to (d) from the viewpoint of enhancing the adhesion to the substrate. The above is more preferable. From the viewpoint of enhancing the scratch resistance of the cured film, the content of the acrylic polyol (a) is preferably 20% by weight or less based on the total weight of the components (a) to (d).

The content of the low molecular weight polyol (b) is 0.5 to 17% by weight based on the total weight of the components (a) to (d). The content of the low molecular weight polyol (b) is preferably 1% by weight or more based on the total weight of the components (a) to (d) from the viewpoint of enhancing the scratch resistance of the cured film. The content of the low molecular weight polyol (b) is preferably 15% by weight or less based on the total weight of the components (a) to (d) from the viewpoint of enhancing the adhesion to the substrate.

The content of the silica particles (c) is 36 to 79% by weight based on the total weight of the components (a) to (d). The content of the silica particles (c) is the components (a) to (d) from the viewpoint of enhancing the scratch resistance of the cured film, enhancing the transparency of the cured film, and enhancing the adhesion to the substrate. It is preferable that it is 38% by weight or more with respect to the total weight of the above. The content of the silica particles (c) is the components (a) to (d) from the viewpoint of enhancing the scratch resistance of the cured film, enhancing the transparency of the cured film, and enhancing the adhesion to the substrate. It is preferably 77% by weight or less based on the total weight of

The amount of the catalyst (e) used is 0.1 to 2.2 parts by weight based on 100 parts by weight of the silica particles (c). The amount of the catalyst (e) used is preferably 0.2 parts by weight or more, and is 0.3 parts by weight or more, based on 100 parts by weight of the silica particles (c) from the viewpoint of enhancing the progress of the curing reaction. Is more preferable. The amount of the catalyst (e) used is preferably 2.1 parts by weight or less, and 2.0 parts by weight or less with respect to 100 parts by weight of the silica particles (c), from the viewpoint of enhancing the adhesion to the substrate. Is more preferable.

The acrylic polyol (a), the low molecular weight polyol (b), and the polyisocyanate (d) are blended in such an amount that the equivalent ratio of the isocyanate group of (d)/{the total hydroxyl group of (a) and (b)} is 0. The ratio is from 0.4 to 2.4. The ratio of the equivalent ratio is preferably 0.5 or more from the viewpoint of enhancing the scratch resistance of the cured film. The ratio of the equivalent ratio is preferably 2.2 or less, and more preferably 2.0 or less from the viewpoint of enhancing the adhesion to the substrate. In addition, since the isocyanate group content (%) of the polyisocyanate (d) is defined by a theoretical value or an actual measurement value (JIS K1603-1), the required amount is calculated by the following formula 1 using these values. It can be calculated.

<Organic solvent>
The thermosetting coating composition containing the components (a) to (e) can be prepared by diluting it with an organic solvent.

Examples of the organic solvent include alcohol-based, carboxylic ester-based, ketone-based, amide-based, ether-based, aliphatic and aromatic hydrocarbon-based solvents. Examples of alcohol solvents include methanol, isopropyl alcohol, n-butanol, diacetone alcohol, 2-methoxyethanol (methylcellosolve), 2-ethoxyethanol (ethylcellosolve), 2-butoxyethanol (butylcellosolve), tertiary amyl. Examples thereof include alcohol and diacetone alcohol. Examples of the carboxylic acid ester-based solvent include ethyl acetate, n-propyl acetate, butyl acetate, butyl formate and the like. Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, acetone and cyclohexanone. Examples of the amide solvent include dimethylformamide and dimethylacetamide. Examples of ether solvents include diethyl ether, methoxytoluene, 1,2-dimethoxyethane, 1,2-dibutoxyethane, 1,1-dimethoxymethane, 1,1-dimethoxyethane, 1,4-dioxane, and tetrahydrofuran. Etc. Examples of the aliphatic and aromatic hydrocarbon solvents include hexane, pentane xylene, toluene and benzene. The organic solvents can be used alone or in combination. Among these, tertiary alcohol polar solvents such as diacetone alcohol and tertiary amyl alcohol are preferable.

In the thermosetting coating composition of the present invention, an ultraviolet absorber can be used in order to enhance the weather resistance of the cured film or prevent the deterioration of the resin member as the base material due to the ultraviolet rays transmitted through the cured film.

As the ultraviolet absorber, known ones can be used without limitation, and examples thereof include salicylate compounds, benzophenone compounds, benzotriazole compounds, hydroxyphenyltriazine compounds, and the like. Examples of the benzophenone compound include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-. Examples of salicylate compounds such as 2-hydroxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone. Phenyl salicylate, p-tert. -Butylphenyl salicylate, p-(1,1,3,3,-tetramethylbutyl)phenyl salicylate, 3-hydroxyphenylbenzoate, phenylene-1,3-dibenzoate, etc. 2-hydroxy-5-methylphenyl)benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-5-tert.-butylphenyl)-5-chlorobenzotriazole, 2 -(2-hydroxy-3,5-di-tert.-butylphenyl)benzotriazole, 2-(2-hydroxy-5-tert.-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octyloxy) Examples of hydroxyphenyltriazine-based compounds such as phenyl)benzotriazole include 2,4-bis(2-hydroxy-4-butyroxyphenyl)-6-(2,4-bis-butyroxyphenyl)-1,3,5. -Triazine, 2-[4[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethoxyphenyl)-1,3. Examples thereof include 5-triazine and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine. The UV absorbers can be used alone or in combination. Among these, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy) is preferable because it has good compatibility with the coating film forming components (a) to (d) and has a large extinction coefficient in the ultraviolet region. ] Phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine is preferred.

If necessary, the thermosetting coating composition of the present invention may contain various conventional additives such as a leveling agent, an antioxidant, an antifoaming agent and a rheology control agent.

<Cured film>
The thermosetting coating composition of the present invention can form a cured film on the surface of a base material by applying the heat-curable coating composition to a base material by a coating method that is usually used for a coating material and heating and curing. The obtained cured film has excellent scratch resistance, adhesiveness, and transparency, and thus can be used as a so-called hard coat film.

As the base material, a known resin base material (member) can be used regardless of its type. For example, various resin base materials (members) can be used regardless of whether they are thermoplastic resins or thermosetting resins. Specific examples thereof include polymethylmethacrylate resin, polycarbonate resin, polystyrene resin, acrylonitrile/styrene copolymer resin, polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, and polyamide resin.

The method of applying the thermosetting coating composition of the present invention to a resin substrate (member) is not particularly limited, and includes bar coater coating, brush coating, flow coating, dip coating, spray coating, spin coating, and the like. Known methods can be adopted.

The temperature at which the thermosetting coating composition of the present invention is heat-cured may be appropriately adjusted depending on the heat resistance and thermal deformability of the base resin used, but is preferably 50° C. or higher and 150° C. or lower. More preferably, it is 80° C. or higher and 150° C. or lower. The heating time is about several minutes to several hours, depending on the heating temperature. The thermosetting coating composition of the present invention can be cured (crosslinked) in about 10 to 20 minutes even at a heating temperature of about 100 to 120°C, and thus has excellent production efficiency.

The thickness of the cured film is preferably 0.5 μm or more, and more preferably 1 μm or more, from the viewpoint of enhancing the weather resistance of the resin base material (member) serving as the base material. The thickness of the cured film is preferably 30 μm or less, and more preferably 20 μm or less, from the viewpoint of enhancing the adhesion of the cured film and suppressing the generation of cracks during curing of the cured film.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<raw material>
The compounds used in the examples or comparative examples are shown below.
<Acrylic polyol (a)>
<Production of acrylic polyol (a-1)>
723.8 parts by weight of diacetone alcohol (DAA) was charged as a polymerization solvent into a reaction vessel equipped with a stirrer, a nitrogen introducing tube and a cooling tube, and heated to 85° C. while blowing nitrogen gas. To this, 100 parts by weight of 2-hydroxyethyl methacrylate (0.77 mol), 207.7 parts by weight of cyclohexyl methacrylate (1.23 mol), and a hydrocarbon diluted product of t-hexyl peroxypivalate as a radical polymerization initiator ( A mixture containing 4.4 wt% of solid content concentration: 70 wt%, NOF Corporation, trade name: Perhexyl PV) was added dropwise over 2 hours. After polymerizing for further 2 hours, the mixture was cooled to room temperature, and a solution of acrylic polyol (a-1) (solid content concentration: 30% by weight, weight average molecular weight: 50,000, theoretical hydroxyl value: 140 mg·KOH/g). Got

<Production of acrylic polyol (a-2)>
784.2 parts by weight of DAA as a polymerization solvent was charged into a reaction vessel equipped with a stirrer, a nitrogen introducing tube and a cooling tube, and heated to 85° C. while blowing nitrogen gas. To this, 50.0 parts by weight (0.38 mol) of 2-hydroxyethyl methacrylate, 283.3 parts by weight (1.68 mmol) of cyclohexyl methacrylate, and hydrocarbon dilution of t-hexyl peroxypivalate as a radical polymerization initiator. A mixture containing 4.8 parts of a product (solid content concentration: 70% by weight, NOF Corporation, trade name: Perhexyl PV) was added dropwise over 2 hours. After polymerizing for another 2 hours, the mixture was cooled to room temperature, and a solution of acrylic polyol (a-2) (solid content concentration: 30% by weight, weight average molecular weight: 45,000, theoretical hydroxyl value: 65 mg·KOH/g). Got

<Low molecular weight polyol (b)>
(B-1) Trimethylolpropane (molecular weight: 135, hydroxyl value: 1,254 mg·KOH/g)
(B-2) Cyclohexyldimethanol (molecular weight: 144, hydroxyl value: 778 mg.KOH/g)
(B-3) Glycerin (molecular weight: 92, hydroxyl value: 1,800 mg·KOH/g)
(B-4) Polycaprolactone tetraol (molecular weight: 426, hydroxyl value: 525 mg·KOH/g, manufactured by Perstorp, Polyol 4525)

<Silica particles (c)>
(C-1) Methyl isobutyl ketone-dispersed silica sol (solid content concentration: 30% by weight, average particle size: 10 to 20 nm, manufactured by Nissan Kagaku, MIBK-ST)
(D-2) Ethyl acetate-dispersed silica sol (solid content concentration: 30% by weight, average particle diameter: 10 to 20 nm, manufactured by Nissan Chemical Co., Ltd., EAC-ST)

<Polyisocyanate (d)>
(D-1) Isocyanurate body of hexamethylene diisocyanate (solid content concentration: 100% by weight, isocyanate group content 23.0%, Asahi Kasei Chemical Co., Ltd., Duranate TPA-100)
(D-2) Hexamethylene diisocyanate allophanate body (solid content concentration: 80% by weight, isocyanate group content rate 15.5%, Sumika Bayer Urethane Co., Desmodur XP2679)

<Catalyst (e)>
DBU-formate (manufactured by San-Apro, U-CAT SA603, pKa of formic acid: 3.8)
DBU-octylate salt (U-CAT SA102, manufactured by San-Apro, pKa of octylic acid: 4.9)
DBU-oleate (U-CAT SA106, manufactured by San-Apro, pKa of oleic acid: 4.8)
DBU-phenol salt (U-CAT SA1, manufactured by San-Apro, pKa of phenol: 9.9)
DBN-octylate (manufactured by San-Apro, U-CAT SA1102, pKa of octylic acid: 4.9)

<Other catalysts not corresponding to the above catalyst (e)>
Dibutyltin dilaurate DBU
DBN
Sodium acetate DBU-paratoluenesulfonate (U-CAT SA506, manufactured by San-Apro Ltd., pKa of paratoluenesulfonic acid: -2.8)

<Organic solvent>
Diacetone alcohol (DAA)
<Leveling agent>
Polyether-modified polydimeryl siloxane (BYK-333, manufactured by Big Chemie)

<Production of thermosetting coating composition>
In a polypropylene container with a lid, 56.7 parts by weight of the solution of the acrylic polyol (a-1) obtained above (17.0 parts by weight of the acrylic polyol (a-1), and 39.7 parts of DAA as a solvent). 3 parts by weight of trimethylolpropane (b-1) as the low molecular weight polyol (b) and 200 parts of methyl isobutyl ketone dispersed silica sol (c-1) (MIBK-ST) as the silica particles (c). Parts by weight (60 parts by weight of silica particles (c) and 140.0 parts by weight of MIBK as a solvent), and isocyanurate form of hexamethylene diisocyanate (d-1) (duranate TPA-100) as polyisocyanate (d). 20.0 parts by weight, DBU-formate (U-CAT SA603) as catalyst (e) 0.6 parts by weight, DAA as diluent solvent 153.7 parts by weight, and polyether-modified polydimeryl siloxane as leveling agent. 0.4 parts by weight of (BYK-333) was blended to obtain the blend of Example 1. The following (1) was evaluated for the obtained blend. The results are shown in Table 3. After the evaluation, the thermosetting coating composition of Example 1 was obtained. The following (2) was evaluated for the obtained thermosetting coating composition. The results are shown in Table 3.

<Examples 2 to 20, Comparative Examples 1 to 15>
<Production of thermosetting coating composition>
The compositions and proportions shown in Tables 1 to 4 were used to obtain the formulations of Examples 2 to 20 and Comparative Examples 1 to 15 and the thermosetting coating composition by the method described in Example 1. The following formulations (1) and (2) were evaluated for the obtained formulations and thermosetting coating compositions. The results are shown in Tables 3 and 4.

<Creation of cured film>
Polycarbonate (PC) resin plates (Mitsubishi Gas Chemical Co., Inc., Iupilon, size: 5 cm×8 cm) were prepared by using the thermosetting coating compositions obtained above in an environment set at 25° C. and a relative humidity of 40% RH. ) Was coated by a bar coater coating method so that the film thickness after curing would be 10 to 12 μm, and heat-cured at 115° C. for 20 minutes to obtain a test piece having a cured film. After leaving the obtained test piece having a cured film at 25° C. for 30 minutes, the following evaluations (3) to (5) were performed. The results are shown in Tables 3 and 4.

(1) Evaluation of Solubility of Catalyst The obtained blend was mixed at 25° C. using a mix rotor (MIX-ROTAR MR5 manufactured by AS ONE), and the time until all the catalyst was dissolved was measured.
○: less than 1 hour ×: more than 1 hour

(2) Evaluation of curability A few drops of the obtained thermosetting coating composition were applied on a silicon wafer (manufactured by Silicon Technology Co., Ltd., size: 2 cm×2 cm), and heat treatment was performed at 115° C. for 20 minutes. The infrared absorption spectra before and after were measured by a transmission method. Before heating, the solvent was volatilized by blowing nitrogen so that the influence of the C—H stretching peak intensity of the solvent was not affected as much as possible, and a dry coating film was obtained, after which the infrared absorption spectrum was measured. The isocyanate (NCO) group consumption rate was calculated based on the following formula from the N=C=O antisymmetric stretching peak intensity present at 2270 cm ⁻¹ and the C—H stretching peak intensity present at 2952 cm ⁻¹ . Further, each catalytic ability was evaluated as follows based on the obtained NCO group consumption rate.
○: 85% or more ×: less than 85%

(3) Evaluation of Scratch Resistance Steel wool (#000) on which a load of 13.7 KPa was placed was placed on the surface of the cured film of the test piece and tested under the test conditions of 11 reciprocations with a rubbing tester, and then the haze (%). And the appearance was evaluated according to the following evaluation criteria.
◯: The value obtained by subtracting the haze before the test from the haze after the test is 5 or less. ×: The value obtained by subtracting the haze before the test from the haze after the test is larger than 5.

(4) Evaluation of Transparency The haze (%) of the test piece having the cured film was measured with a haze meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.), and the transparency was evaluated according to the following evaluation criteria.
○: haze 5.0% or less x: haze greater than 5.0%

(5) Adhesion evaluation In accordance with JIS K 5400 8.5.2, cuts that penetrate the cured film of the test piece and reach the ground surface with a grid tape method are made in a grid pattern with an interval of 1 mm. The adhesive state was set to 100 and the adhesive state of the coating film after the tape was peeled off was visually observed, and the adhesiveness was evaluated according to the following evaluation criteria.
○: No peeling ×: Peeling

It was found that the formulations of Examples 1 to 20 and the thermosetting coating composition satisfy all the evaluation criteria of (1) and (2) above. Further, it was found that the cured films of Examples 1 to 20 satisfied all the evaluation criteria of (3) to (5) above. Therefore, according to the thermosetting coating compositions of Examples 1 to 20, the urethane compositions containing silica particles were used at a temperature not higher than the heat distortion temperature of the synthetic resin while using a catalyst having good solubility in an organic solvent. It has been found that a curing (crosslinking) reaction can be sufficiently advanced even at a temperature to form a cured film having excellent scratch resistance, transparency, and adhesion.

On the other hand, it was confirmed that when dibutyltin dilaurate was used as the catalyst as in Comparative Example 1, the curing (crosslinking) reaction did not proceed sufficiently. It was also found that when DBU or DBN was used as the catalyst as in Comparative Examples 2 and 3, these catalysts were not dissolved but were precipitated. Furthermore, as in Comparative Example 4, when sodium carboxylic acid metal salt sodium acetate was used as the catalyst, it was confirmed that it took time to dissolve the catalyst. Further, as in Comparative Example 5, it was found that when the DBU salt of p-toluenesulfonic acid having a pKa of −2.8 was used, the curing (crosslinking) reaction did not proceed sufficiently.

Further, in the thermosetting coating compositions of Comparative Examples 6 to 15, at least the above (2) to (5) because the contents, blending amounts, or usage amounts of the components (a) to (e) are inappropriate. It was confirmed that one evaluation criterion in the evaluation could not be satisfied.

Claims (4)

Acrylic polyol (a), low molecular weight polyol (b), silica particles (c), polyisocyanate (d) and catalyst (e) are contained,
The low molecular weight polyol (b) has a molecular weight of 60 to 500, and a hydroxyl value of 500 to 2,000 mg·KOH/g,
The catalyst (e) has the following general formula (1)
[In the formula, X represents an acid having a pKa of 2 to 12] and/or the following general formula (2).
[Wherein, X represents an acid having a pKa of 2 to 12], which is a tertiary amine salt,
The acrylic polyol (a) is 0.5 to 21% by weight, the low molecular weight polyol (b) is 0.5 to 17% by weight, and the silica particles (c) are based on the total weight of the above (a) to (d). In an amount of 36 to 79% by weight, and 0.1 to 2.2 parts by weight of the catalyst (e) with respect to 100 parts by weight of the silica particles (c),
The acrylic polyol (a), the low molecular weight polyol (b), and the polyisocyanate (d) have an equivalent ratio of the isocyanate group of (d)/{the total hydroxyl group of (a) and (b)} is 0.4 to A thermosetting coating composition, which is blended in a ratio of 2.4. A cured film formed from the thermosetting coating composition according to claim 1. The cured film according to claim 2, wherein the cured film is a hard coat film. A resin member comprising the cured film according to claim 2.