JPS6333512B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a curable resin composition useful for coatings, and more specifically, a composition comprising a vinyl polymer having a specific functional group in its side chain, a polyhydroxy compound, and a curing catalyst as essential components.
This invention relates to a new and useful resin composition for coatings. In recent years, the development of low-temperature drying paints has been actively promoted as part of energy-saving measures in the paint field. Under these circumstances, polyurethane paints that use polyisocyanate as a curing agent have excellent curing properties at low temperatures and provide cured coatings with excellent physical properties, so they are being used for a variety of purposes. There is. However, such urethane paints have the problem of toxicity due to the raw material isocyanate, and also have the disadvantage that the paint film turns yellow in a short period of time, especially when used as a clear paint. As a paint free from such drawbacks, paints using a vinyl polymer having an alkoxysilyl group in the side chain as a base resin have been proposed (for example, Japanese Patent Publication No. 46-29280), but these paints are still satisfactory in terms of mechanical strength. The current situation is that we are not getting anything. In view of the above, the present inventors have conducted intensive research and have found a low-temperature curable resin composition that does not have the above drawbacks and has excellent yellowing resistance and mechanical strength, and has accomplished the present invention. . That is, the present invention uses the general formula [However, R ₁ in the formula is a C ₁ to C ₄ linear or branched alkyl group, a C ₁ to _{C 4} alkoxy-substituted alkyl group, or a phenyl group, and R ₂ is an OR ₁
Alternatively, it represents a C ₁ -C ₄ straight chain or branched alkyl group. ] A vinyl polymer (A) having an alkoxyl group in the side chain, a polyhydroxy compound (B) having at least two hydroxyl groups per molecule, and (C) a curing catalyst, combined with the above vinyl polymer. -SiOR ₁ bond in (A)
The above-mentioned curing catalyst (C) is added to the above-mentioned polymer (A) and compound (B) in such a proportion that the number of hydroxyl groups in the above-mentioned polyhydroxy compound (B) is 0.1 to 1.0 per unit. It is an object of the present invention to provide a curable resin composition for paint, which contains 0.01 to 10% by weight based on the total solid content. In the present invention, the “vinyl polymer (A) having an alkoxysilyl group in the side chain” has the general formula

[Formula] (However, R ₁ is a C ₁ to C ₄ straight chain or branched alkyl group or phenyl group, and R ₂ is OR ₁ or a C ₁ to C ₄ straight chain or branched alkyl group. ) is a vinyl polymer having a group represented by Such a polymer (A) can be prepared by polymerizing a mixture of the above-mentioned vinyl monomer containing an alkoxysilyl group and another vinyl monomer copolymerizable with the monomer, or by separately This is achieved by reacting the prepared vinyl polymer having an unsaturated group or an epoxy group in its side chain with the aminosilanes, hydrosilanes, or mercaptosilanes containing the alkoxysilyl group. Specific examples of the "vinyl monomer having an alkoxysilyl group" used when preparing the polymer (A) of the present invention by a copolymerization method include γ-methacryloyloxypropyltrimethoxysilane, γ-
Methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-acryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyl Examples include methyldiethoxysilane, vinyltris(β-methoxyethoxy)silane, allyltrimethoxysilane, and P-vinylphenyltrimethoxysilane. Typical examples of other vinyl monomers that can be copolymerized with these monomers include methyl methacrylate, ethyl methacrylate, butyl methacrylate,
- Methacrylic acid esters such as ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, and cyclohexyl acrylate; itaconic acid , mono- or dialkyl esters of fumaric acid or maleic acid; aromatic unsaturated hydrocarbons such as styrene, α-methylstyrene, vinyltoluene; β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, β -Hydroxyalkyl (meth)acrylates such as hydroxypropyl methacrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid; perfluoroalkyl (C ₃ - _{C 18} )
Alkylene (meth)acrylate, N-alkyl-N-(meth)acryloyloxyalkylene perfluoroalkyl ( _C3 - _C18 ) sulfonamide,
N-alkyl-N-(meth)acryloyloxyalkylene perfluoroalkyl ( _{C3- C18} ) carboxylic acid amide, N-alkyl-N-vinyloxyalkylene perfluoroalkyl ( _C3 - _C18 )
Sulfonamide, perfluoroalkyl ( _C3 ~
_C18 ) perfluoroalkyl ( _C3 - _C18 )-containing vinyl compounds such as alkylene vinyl ethers; furthermore, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N,N
-dimethylacrylamide, diacetone acrylamide, N,N-dimethylaminoethyl methacrylate, vinylpyridine, vinyl chloride, vinyl acetate and the like. Introduction of an alkoxysilyl group into the vinyl polymer (A) by the copolymerization method of an alkoxysilyl group-containing monomer can be achieved by polymerizing the exemplified monomers by a known method. However, in this case, it is most preferable to use a solution radical polymerization method.
During polymerization, aromatic hydrocarbons such as benzene, toluene, and xylene, hexane, heptane,
Aliphatic hydrocarbons such as cyclohexane, esters such as ethyl acetate, butyl acetate, and ethylene glycol monoethyl ether acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, methanol, ethanol, isopropanol, n-butanol, Alcohol solvents such as isobutanol and ethylene glycol monoethyl ether can be used, but from the viewpoint of storage stability of the resulting resin solution and paints using it, the alcohol solvent should be used in an amount of 5% or more by weight of the total amount of solvent. It is preferable. Also, during polymerization, t-
dodecyl mercaptan, lauryl mercaptan,
Mercaptans such as thioglycolic acid alkyl esters, β-mercaptopropionic acid, and β-mercaptoethanol, and α-methylstyrene dimer can be used, and thereby the average molecular weight of the vinyl polymer (A) can be increased to 2,000 to 30,000. 5000〜
It is preferable to set it to about 20,000. The copolymerization amount of the alkoxysilyl group-containing monomer is preferably in the range of 1 to 50% by weight from the viewpoint of curability and cost. In addition, the polymer (A) may contain a monomer having no alkoxysilyl group, a vinyl monomer having an epoxy group, or a vinyl-polymerizable double bond (preferably one having a different reactivity). A production method consisting of polymerizing two monomers to synthesize a vinyl polymer having an epoxy group or an unsaturated group in the side chain, and reacting it with aminosilanes, hydrosilanes, or mercaptosilanes. It is also manufactured. In this case, specific examples of the vinyl monomer having an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and the like. In addition, as aminosilanes, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,
Examples include N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane. Examples of mercaptosilanes include γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane. Examples of hydrosilanes include trimethoxysilane, triethoxysilane, methyldiethoxysilane, and phenyldimethoxysilane. The molecular weight and concentration of alkoxysilyl groups of the polymer (A) obtained by the production method are also preferably similar to the values explained for the copolymerization method. The polyhydroxy compound (B) added to component (A) is
A compound containing at least two hydroxyl groups per molecule. The molecular weight of this polyhydroxy compound (B) is preferably about 62 to 20,000, particularly about 62 to 10,000. Representative examples of component (B) include ethylene glycol, propylene glycol, 1,6-hexanediol, trimethylolpropane, glycerin,
Low molecular weight polyols such as pentaerythritol and sorbitol; High molecular weight polyols such as polyester resins, alkyd resins, vinyl polymers, and polyether polyols having hydroxyl groups; Combinations of the above polyhydroxy compounds and β-propiolactone or ε-caprolactone Adduct; 2 or more silanol groups in one molecule

Examples include silicon compounds containing the formula: The amount of component (B) to be blended is preferably such that the number of hydroxyl groups per one Si- _OR bond in component (A) is 0.1 to 1.0. The curing catalyst (C) used in the present invention includes amine compounds, metal-containing compounds, acidic substances, etc.
Representative examples include n-butylamine, t-butylamine, di-n-butylamine, hexylamine,
Ethylenediamine, di-n-butylamine octylate, tetraisopropyl titanate, tetrabutyl titanate, tin octylate, lead octylate, cobalt octylate, zinc octylate, calcium octylate, dibutyltin diacetate, dibutyltin dioctoate, dibutyl Examples include tin dilaurate, p-toluenesulfonic acid, and trichloroacetic acid. The amount of these catalysts used is 0.001 to 10% by weight, preferably 0.01% by weight based on the total solid content of (A) and (B).
~2% by weight. The composition of the present invention can be made into a paint as it is, or by blending pigments, solvents, additives, and conventionally known curing agents such as amino resins, polyisocyanates, blocking isocyanates, and epoxy resins as necessary. , apply such paint to the object to be coated and leave it at room temperature for several days or at 60 to 150℃ for 20 minutes.
By baking for ~30 minutes, a coating film with excellent mechanical strength and yellowing resistance can be obtained. The composition of the present invention can be used for coating automobile repair, woodworking, building materials, and various plastics for which urethane-based paints have conventionally been used. Of course, this does not in any way preclude the use of the composition of the present invention for purposes other than coating, such as for fiber treatment or paper treatment. Next, the present invention will be explained with reference to Examples, in which all parts are by weight unless otherwise specified. Reference Example 1 (Preparation of vinyl polymer A-1) Thermometer, stirring device, dropping funnel, nitrogen introduction tube,
and xylene in 3 flasks equipped with condensers.
400 parts of n-butanol and 300 parts of n-butanol were charged, and the temperature was raised to 85°C under a nitrogen stream. Then, styrene was added at the same temperature.
300 parts, methyl methacrylate 300 parts, n-butyl methacrylate 250 parts, n-butyl acrylate
100 parts of γ-methacryloyloxypropyltrimethoxysilane, 10 parts of azobisisobutyronitrile, 10 parts of t-butylper2-ethylhexanoate, and 300 parts of xylene.
The solution was added dropwise over a period of time and maintained at the same temperature for 17 hours to obtain a polymer solution (A-1) with a nonvolatile content of 51.4% and a Gardner color of 1 or less. Reference Example 2 (Preparation of Vinyl Polymer A-2) 200 parts of styrene, 100 parts of methyl methacrylate, 600 parts of n-butyl methacrylate, and 100 parts of γ-methacryloyloxypropyltrimethoxysilane are used as comonomer components. Except for this, the same procedure as in Reference Example 1 was conducted to obtain a polymer solution (A-2) with a nonvolatile content of 51.3% and a Gardner color of 1 or less. Reference Example 3 (Preparation of vinyl polymer A-3) Methyl methacrylate as a comonomer component
A polymer solution (A-3) having a nonvolatile content of 50.5% and a Gardner color of 1 or less was obtained in exactly the same manner as in Reference Example 1 except that 300 parts of vinyl acetate, 500 parts of vinyl acetate, and 200 parts of vinyltriethoxysilane were used. Reference Example 4 (Preparation of polyhydroxy compound B-1) 134 parts of trimethylolpropane, 342 parts of ε-caprolactone, and zinc acetylacetonate
A mixture consisting of 0.46 parts was heated at 150° for 4 hours under a nitrogen stream to give a hydroxyl value of 335 and a Gardner color of 1 to 1.
A liquid adduct (B-1) of No. 2 was obtained. Reference Example 5 (Preparation of polyhydroxy compound B-2) 136 parts of pentaerythritol, 456 parts of ε-caprolactone, and 0.59 parts of zinc acetylacetonate
A liquid adduct (B-2) having a hydroxyl value of 354 and a Gardner color of 1 to 2 was obtained in the same manner as in Reference Example 4. Examples 1 to 4, Comparative Examples 1 to 2 A clear paint was prepared according to the formulation shown in Table 1 below, and applied to a zinc phosphate treated steel plate using a doctor blade to a film thickness of approximately 60μ. After that, it was force-dried at 80°C for 20 minutes and further dried at 23°C for 2 days. Table 1 shows the performance of the resulting coating film. As shown in Table 1, the coating film properties and yellowing resistance of the paint prepared from the composition of the present invention were both good. Here, the yellowing resistance is determined by applying the above clear paint on the white urethane coating that has been applied in advance, and drying it in the same manner as above.
By examining the change in the degree of yellowing of the paint film irradiated with a 15W germicidal lamp from a distance of 20cm for 24 hours (specifically, the Δb value - the difference between the b value of the unirradiated paint film and that of the irradiated paint film). I made a judgment based on the evaluation. The smaller the Δb value, the better the yellowing resistance.

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Claims (1)

[Claims] 1 (A) General formula [However, R ₁ is a C ₁ to C ₄ linear or branched alkyl group, C ₁ to _{C 4} alkoxy-substituted alkyl group, or phenyl group, and R ₂ is OR ₁ or a C ₁ to _{C 4} linear or branched alkyl group. shall represent a branched alkyl group. ] A vinyl polymer having an alkoxyl group in the side chain, (B) a polyhydroxy compound containing at least two hydroxyl groups per molecule, and (C) a curing catalyst, as essential components, Polymer (A)
The curing catalyst (C) is added to these vinyl polymers (A) in such a proportion that the number of hydroxyl groups in the _compound (B) is 0.1 to 1.0 per one -SiOR bond in the vinyl polymer (A). and a polyhydroxy compound (B) in a proportion of 0.001 to 10% by weight based on the total solid content.