JPH05345879A - Curable coating composition - Google Patents

Abstract

PURPOSE:To obtain a excellent curable coating composition consisting essentially of a hydrolyzable silyl group-containing vinyl based polymer and excellent in acid and scratch resistances. CONSTITUTION:The curable coating composition is obtained by blending 100 pts.wt. total amount of 10-99 pts.wt. vinyl based polymer having >=2000 number- average molecular weight and 1-90 pts.wt. polycarbonate polyol compound having at least one carbonate bond and at least two hydroxyl groups in one molecule with 0.001-10 pts.wt. curing catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition for paints which has low toxicity and is improved in acid resistance, scratch resistance, 1-liquid storage stability and curability. In particular, it relates to a curable composition which is useful as a coating material for automobile top coating.

[0002]

2. Description of the Related Art Conventionally, paint resins used for coating automobiles, building exteriors, industrial machinery, steel furniture, plastics, etc. are mainly melamine resins such as alkyd melamine and acrylic melamine or two-component urethane resins. Is.

Among these, the melamine resin has a problem that harmful formalin is generated at the time of curing and that the cured coating film is resistant to acid and is affected by acid rain. Also,
With the two-component urethane resin, the toxicity of the isocyanate compound used is a problem.

In order to solve these problems, the present inventors have investigated the use of a vinyl polymer having a silicon atom bonded to a hydrolyzable group (hereinafter, also referred to as hydrolyzable silyl group) in a coating material. I'm doing it. As a result, they have found that this polymer solves the above problems and provides a curable resin for coatings having excellent weather resistance, and has previously filed a patent application (JP-A-63-132977, etc.).

In the vinyl polymer having a hydrolyzable silyl group, the silyl group is hydrolyzed by the moisture in the air and undergoes a condensation reaction to form a stable siloxane bond and cure, so that an acrylic melamine or It has superior chemical resistance and weather resistance compared to melamine resins such as alkyd melamine and two-component urethane resins.

[0006]

However, when the above-mentioned vinyl polymer having a hydrolyzable silyl group is used as a coating material for automobile top coating, there are the following problems.

[0007] First, scratch resistance to car wash brushes and running dust is insufficient, and flexible components such as polyester components are copolymerized or blended in order to enhance scratch resistance. Then, the acid resistance of the coating film deteriorates.

Secondly, in recent years, there has been a tendency to regulate the total amount of solvent generated when coating a paint, such as the VOC (volatile organic substance) regulation in the United States. However, it is difficult for a coating consisting of the above-mentioned polymer alone to have a high solid content that satisfies the VOC regulations of the United States.

Thirdly, as a curing catalyst, a tin compound such as di-n-butyltin (IV) dilaurate, a sulfonic acid such as p-toluenesulfonic acid, or di-2
-When an acidic phosphate ester such as ethylhexyl phosphate is added, the activity is high even at room temperature,
1-liquid storage stability is not always sufficient.

[0010]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have excellent scratch resistance and acid resistance, as well as high solidity and one-liquid storage stability. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, (A) the main chain is substantially composed of a vinyl polymer chain, and the main chain end and / or
Vinyl polymer having a number average molecular weight of 2000 or more and having at least one silicon atom bonded to a hydrolyzable group in the side chain of 10 to 99 parts (parts by weight, the same hereinafter) and (B) per molecule Curable properties for paints, in which 0.001 to 10 parts of (C) curing catalyst is added to 100 parts in total of 1 to 90 parts of a polycarbonate polyol compound having at least one carbonate bond and at least two hydroxyl groups on average. It relates to a composition.

[0012]

[Functions and Examples] The hydrolyzable silyl group-containing vinyl polymer of the component (A) used in the present invention has a main chain consisting essentially of a vinyl polymer chain, and has main chain terminals and / or side chains. At least one silicon atom (hydrolyzable silyl group) bonded to a hydrolyzable group in one molecule, preferably 2 to
It is a polymer having 10. When the number of hydrolyzable silyl groups is less than 1 in one molecule, the crosslinking density becomes too small, and the effects resulting from the siloxane bond, such as weather resistance and chemical resistance, are not sufficiently exhibited. Further, when the number of hydrolyzable silyl groups exceeds 10 in one molecule, the internal stress of the cured coating film becomes large and the coating film becomes liable to crack.

Since the vinyl polymer containing a hydrolyzable silyl group is substantially composed of a vinyl polymer chain, the cured product has excellent weather resistance, chemical resistance, etc., and the copolymer composition can be changed. A wide range of resin designs from soft to hard are possible. In the vinyl polymer, about 60% (% by weight, the same applies below) of the units constituting the main chain, or more, preferably about 80% or more is composed of vinyl monomer units.
Therefore, the vinyl polymer as the component (A) may partially contain a urethane bond or a siloxane bond in the main chain or side chain.

Examples of the hydrolyzable silyl group include those represented by the general formula (I):

[0015]

[Chemical 1]

(In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, and R ² is a hydrogen atom or 1 to 4 carbon atoms.
It is a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 10 to 4, preferably 1 to 4, an aryl group having 6 to 10 carbon atoms and an aralkyl group having 7 to 10 carbon atoms, and R ¹ and R ²
When each is 2 or more, they may be the same group or different groups; and a represents an integer of 0 to 2).

If R ¹ has more than 10 carbon atoms, the hydrolytic reactivity of the hydrolyzable silyl group is lowered, and even if R ¹ is a group other than an alkyl group, for example, a phenyl group or a benzyl group, the hydrolysis is not possible. Reactivity decreases. Specific examples of R ¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a hexyl group and an octyl group. Specific examples of the alkyl group for R ² include the same groups as the alkyl group for R ¹ , and specific examples of the aryl group include, for example, a phenyl group, a tolyl group, a cumenyl group, and an aralkyl group. Specific examples include a benzyl group and a phenethyl group.

The hydrolyzable silyl group represented by the general formula (I) may be contained at the terminal of the main chain of the vinyl polymer as the component (A) or may be contained in the side chain. , And may be contained in both the terminal and side chains of the main chain.

If the molecular weight of the polymer as the component (A) is too small, the amount of the non-crosslinking component will increase, so that the number average molecular weight is 20.
Those of 00 or more, preferably 3000 to 10000 are used.
If the molecular weight exceeds 10,000, the viscosity becomes high, and as a result, the solid content concentration during coating must be reduced.

If the molecular weight of one hydrolyzable silyl group in the polymer of the component (A) is too large, the formation of siloxane bonds will be small, and the effects of the present invention will not be sufficiently exhibited. On the contrary, if it is too small, the internal stress increases. for that reason
300 to 5000 is preferable, and 350 to 2500 is particularly preferable.

The polymer as the component (A) is generally composed of units from a vinyl-based monomer, units from a hydrolyzable silyl group-containing monomer, and the like.

The vinyl-based monomer is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth). ) Acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, etc .; unsaturated polycarboxylic acids (maleic acid, fumaric acid, Unsaturated polycarboxylic acid esters such as diesters or half esters of itaconic acid) with linear or branched alcohols having 1 to 20 carbon atoms; styrene, α-methylstyrene, chlorostyrene, styrenesulfone Aromatic hydrocarbon vinyl compounds such as acids, 4-hydroxystyrene and vinyltoluene; vinyl esters and allyl compounds such as vinyl acetate and vinyl diallyl phthalate propionate; nitrile group-containing vinyl compounds such as (meth) acrylonitrile; glycidyl (meth ) Epoxy group-containing vinyl compounds such as acrylates; basic nitrogen atom-containing vinyl compounds such as dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, vinylpyridine and aminoethyl vinyl ether; (Meth) acrylamide, itaconic acid diamide, α-ethyl (meth) acrylamide, crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone, N-butoxymethyl (meth) a Amyl group-containing vinyl compounds such as rylamide, N, N-dimethylacrylamide, N-methylacrylamide, and acryloylmorpholine; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N- Methylol (meth) acrylamide, Aronix 5700 (Toagosei Chemical Industry Co., Ltd.), Placcel FA-1, Placcel FA-4, Plac
vinyl compounds containing hydroxyl groups such as cel FM-1 and Placcel FM-4 (all manufactured by Daicel Chemical Industries, Ltd.); unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid Acid anhydrides such as salts (alkali metal salts, ammonium salts, amine salts, etc.), maleic anhydride, itaconic anhydride; vinyl methyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, maleimide, N-vinyl. Other vinyl compounds such as imidazole and vinyl sulfonic acid are included.

Examples of the hydrolyzable silyl group-containing monomer include monomers having the hydrolyzable silyl group represented by the general formula (I). Specific examples of the alkoxysilyl group-containing vinyl monomer, which is a typical example thereof, include, for example,

[0024]

[Chemical 2]

[0025]

[Chemical 3]

(N is an integer of 1 to 20) and the like.

Units derived from these hydrolyzable silyl group-containing vinyl monomers are preferably contained in the polymer of the component (A) in an amount of 5 to 90%, particularly preferably 11 to 70%.

As the method for producing the polymer as the component (A), generally, the above-mentioned hydrolyzable silyl group-containing monomer is copolymerized with a vinyl monomer, for example, JP-A-54-36395.
The methods shown in JP-A-57-36109, JP-A-57-55953, JP-A-58-157810, etc. are exemplified, but solution weight using an azo radical initiator such as azobisisobutyronitrile is used. It is preferable to manufacture it legally because it is easy to handle.

If necessary, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ
-Mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane,

[0030]

[Chemical 4]

The molecular weight may be adjusted by using a chain transfer agent such as. In particular, if a chain transfer agent having a hydrolyzable silyl group in the molecule, such as γ-mercaptopropyltrimethoxysilane, is used, the hydrolyzable silyl group can be introduced at the end of the vinyl copolymer produced. .

The polymerization solvent used for the solution polymerization is
Hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetic acid esters (ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, isopropanol, n-butanol, etc.), ethers (ethyl cellosolve, butyl cellosolve) , Cellosolve acetate, etc., ketones (methyl ethyl ketone,
Examples thereof include non-reactive solvents such as ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, and acetone), and there is no particular limitation as long as they are such solvents.

The polycarbonate polyol compound as the component (B) used in the present invention has a carbonate bond:

[0034]

[Chemical 5]

At least 1, preferably 1 to 20, more preferably 2 to 10 and 1 hydroxyl group are included in one molecule.
It has at least 2, preferably 2 to 10, more preferably 2 to 6 in the molecule and has a number average molecular weight of 3,000 or less, preferably less than 2000, more preferably 2000 to 300, particularly preferably 1500 to 250. Is a compound.

Since the polycarbonate polyol compound as the component (B) has a hydroxyl group, it forms a siloxy bond with the hydrolyzable silyl group-containing vinyl polymer as the component (A), and since it has a carbonate bond, it has sufficient acid resistance. While maintaining the above, a coating film having sufficient scratch resistance can be obtained.
Moreover, since it has a relatively low molecular weight, it is also effective for high solidification.

When the number of the carbonate bonds in the polycarbonate polyol compound of the component (B) exceeds 20, the acid resistance is rather lowered and the viscosity tends to increase, and when the number of hydroxyl groups exceeds 10, the component (A) The compatibility with the hydrolyzable silyl group-containing vinyl polymer of 1) tends to decrease, and the viscosity tends to increase. Furthermore, if the number average molecular weight exceeds 3000,
The component (B) itself has a high viscosity, and therefore the curable composition for coatings is difficult to be made into a high solid. If it is less than 250, volatility is generated and solid content is less likely to occur, which is not suitable for high solidification.

Specific examples of the polycarbonate polyol compound as the component (B) include PLACCEL CD-205PL, CD-208PL, CD-210 (above, diol), CD-305, manufactured by Daicel Chemical Industries, Ltd. Examples include CD-308 (above, triol) and CD-610 (tetraol).

The amount of the above-mentioned polycarbonate polyol compound added is 1 to 90 parts per 10 to 99 parts, preferably 20 to 95 parts, of the hydrolyzable silyl group-containing vinyl polymer as the component (A).
Parts, preferably 5 to 80 parts, such that the total amount of component (A) and component (B) is 100 parts. If the addition amount of the component (B) is less than 1 part, the viscosity of the curable composition for coatings will be high, and high solidification will be difficult. On the other hand, if the amount added exceeds 90 parts, the hardness and weather resistance decrease.

In the mixing of the components (A) and (B), the ratio of the hydroxyl group equivalent of the mixture to the R ¹ O--Si bond equivalent is 0.01 / 1.0 to 1.5 / 1.0, preferably 0.02 / 1.0.
To 1.0 / 1.0, particularly preferably 0.02 / 1.0 to 0.5 / 1.0
Is. If the equivalent ratio is less than 0.01 / 1.0, sufficient scratch resistance cannot be obtained, while if it exceeds 1.5 / 1.0, curability and water resistance are deteriorated.

Examples of the curing catalyst for the component (C) used in the present invention include organic tin compounds, acidic phosphoric acid esters, reaction products of acidic phosphoric acid esters and amines, saturated or unsaturated polyvalent carboxylic acids or acid anhydrides thereof. Compounds, sulfonic acids or their reaction products with amines, organic titanates, organic aluminum compounds or mixtures thereof.

Among the above curing catalysts, the sulfonic acid group of the sulfonic acid compound is an amine in view of storage stability of one liquid at room temperature and curability during baking at 100 ° C. or higher (usually 120 ° C. or higher). It is preferably a blocked product.

Examples of the sulfonic acid compound include dodecylbenzenesulfonic acid, 1-octanesulfonic acid, p-toluenesulfonic acid, 2-acrylamido-
2-Methylpropanesulfonic acid and the like can be mentioned.

Examples of the amine used for blocking the sulfonic acid group include aliphatic chain amines, aliphatic cyclic amines and aromatic amines. Among the amines, primary and secondary amines having at least one hydroxyl group in one molecule and morpholine are preferable, and morpholine is particularly preferable, from the viewpoint of curability and storage stability in one liquid.

Specific examples of the amine include 2-
(Methylamino) ethanol, diisopropanolamine, 2-amino-2-methyl-1-propanol, 3-amino-1
-Propanol, 1-amino-2-propanol, 6-amino
-1-hexanol, 4-amino-1-butanol, 2-amino
-2-Methyl-1-propanol, morpholine and the like.

The ratio of the amine to the sulfonic acid is 0.5 to 3.0 equivalents of amine, preferably 0.75 to 2.5 equivalents, and particularly preferably 0.9 to 1 equivalent of sulfonic acid group.
It is desirable to be 2.0 equivalents. When the equivalent of amine is less than 0.5 with respect to 1 equivalent of sulfonic acid group, the storage stability of 1-liquid and the appearance of the coating film deteriorate, and when it exceeds 3.0, the coloring and water resistance of the coating film decrease. Tend to do.

The amount of the curing catalyst used as the component (C) is
0.001 to 1 for 100 parts of the total of components (A) and (B)
It is 0 part, preferably 0.05 to 10 parts. If the amount of component (C) used is less than 0.001 part, the curability tends to decrease,
If it exceeds 10 parts, the appearance of the coating film tends to deteriorate.

In the composition of the present invention, organopolysiloxane silanols, tetraalkoxysilanes, alkyltrialkoxysilanes, partial hydrolysates thereof, amino resins such as melamine, and polyols are further added to further reduce the viscosity. It may be added in an amount of preferably 50 parts or less, and more preferably 30 parts or less, based on 100 parts of the total of the components A) and (B). When more than 50 parts of organopolysiloxane silanol is added, the scratch resistance is rather lowered, and when more than 50 parts of tetraalkoxysilane or alkyltrialkoxysilane or its partial hydrolyzate is added, the compatibility is lowered, Internal stress increases. If more than 50 parts of an amino resin such as melamine is added, the acid resistance is rather lowered, and if more than 50 parts of polyol is added, the water resistance is lowered.

A hydrolyzable ester compound as a dehydrating agent and an alkyl alcohol as a solvent may be added to the composition of the present invention.

Specific examples of the dehydrating agent include ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, ethyl silicate and methyl silicate, and hydrolyzable ester compounds such as methyltrimethoxysilane. Can be given. These dehydrating agents may be added during the polymerization of the component (A) or after the polymerization. The amount of the dehydrating agent added is 70 parts or less, preferably 50 parts or less, and more preferably 20 parts or less with respect to 100 parts in total of the components (A) and (B).
When the addition amount of the dehydrating agent exceeds 70 parts, the stabilizing effect of the alkoxysilyl group is almost unchanged, and it becomes difficult to form a high solid.

Examples of the alkyl alcohol as the solvent include alcohols having an alkyl group having 1 to 10 carbon atoms. Specific examples of such alcohol include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, Isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol,
Examples thereof include isoamyl alcohol, hexyl alcohol, octyl alcohol, and cellosolve.

The amount of the alcohol used is not particularly limited, but the amount is 100 parts by weight of the component (A) and the component (B).
It is usually 70 parts or less, preferably 50 parts or less, more preferably 20 parts or less, and when using a solvent alone without a dehydrating agent, it is usually 0.5 to 70 parts, preferably 1 to 50 parts.
Parts, more preferably 2 to 20 parts. When the amount of the alcohol solvent is less than 0.5 part, there is almost no effect of stabilizing the alkoxysilyl group. If it exceeds 70 parts, it will be difficult to achieve high solids.

When the alcohol and the dehydrating agent are used in combination, the storage stability is remarkably improved as compared with the case where the composition comprising the component (A), the component (B) and the component (C) is stored. It The amount of the solvent exhibiting such an effect varies depending on the molecular weights and compositions of the component (A), the component (B) and the component (C) in the composition of the present invention, and cannot be specified unconditionally. May be adjusted so that the solid content concentration and the viscosity are practically required.

When the composition of the present invention is used as a top coat, the weather resistance can be further improved by blending an ultraviolet absorber and a light stabilizer, particularly by using them together.

As the above-mentioned UV absorber, conventionally known ones can be widely used. For example, benzophenone-based, triazole-based, phenylsalicylate-based, diphenylacrylate-based, acetophenone-based UV absorbers are preferable.

As the above-mentioned light stabilizer, those known in the art can be widely used, and for example, bis (2,2,6,6-tetramethyl-4-
Piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), Tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-
Butane tetracarboxylate, tetrakis (1,2,2,6,
6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate and the like. These may be used alone or in combination of two or more.

The amount of the ultraviolet absorber compounded is usually 0.1 to 10 parts, preferably 1 to 5 parts, relative to 100 parts of the solid content of the composition. The light stabilizer content is 10% solids of the composition.
It is usually 0.1 to 10 parts, preferably 1 to 5 parts, relative to 0 parts. If both the ultraviolet absorber and the light stabilizer are less than 0.1 parts, the effect of improving the weather resistance is small, and even if it exceeds 10 parts, the weather resistance is hardly changed and the hardness is rather lowered.

When the composition of the present invention is used as a top coat clear paint, additives such as diluents, cissing inhibitors, leveling agents, etc. depending on the application; Compounds: Epoxy resin, melamine resin, vinyl chloride resin,
Resins such as chlorinated polypropylene, chlorinated rubber and polyvinyl butyral may be added.

The method for preparing the composition of the present invention comprising the above-mentioned components is not particularly limited. For example, the component (A) and the component (B) are cold-blended, or the component (A) and the component (B) are blended. A method of mixing the components and then partially heating the mixture by heating (hot blending) and mixing it with the component (C) can be used.

The composition of the present invention has low toxicity and can be made into a high solid having a solid content of 50 to 70%, for example, spray coating, brush coating, roll coating,
After being applied to the substrate by a method such as dip coating, it is cured by heating at about 80 to 160 ° C to form a cured coating film with excellent chemical resistance such as acid resistance, weather resistance and scratch resistance. .

The composition of the present invention is useful for coating automobiles, building exteriors, industrial machines, steel furniture, plastics and the like, and is particularly useful as a coating material for automobile top coatings.

Next, the composition of the present invention will be described in more detail with reference to Examples.

Synthesis Example 1 First, the following parts 1-1 to 1-4 were prepared.

(Part 1-1) Styrene (hereinafter referred to as ST) 13 g Methyl methacrylate (hereinafter referred to as MMA) 32 g γ-Trimethoxysilylpropylmethyl methacrylate 29 g (hereinafter referred to as TSMA) Butyl acrylate (hereinafter referred to as BA) 25 g Acrylamide (hereinafter referred to as AM) 1 g γ-trimethoxysilylpropyl mercaptan 1 g (hereinafter referred to as TSSH) Methyl alcohol (hereinafter referred to as MeOH) 2 g 2,2′-azobisisobutyronitrile 6 g (hereinafter referred to as AIBN) Xylene 18g Mixed solution of methyl orthoacetate (hereinafter referred to as MOA) 2g (Part 1-2) Solvesso 100 (manufactured by Exxon Chemical Co., Ltd.) 14g (Part 1-3) AIBN 0.6g Xylene 15g Mixed solution of MeOH 2g (Part) 1-4) MOA 4g MeOH 2g mixed solution Next, in a nitrogen atmosphere, the mixed solution of the part 1-1 was added dropwise at a constant rate into the part 1-2 heated to 110 ° C. over 5 hours. Next, the mixed solution of Part 1-3 was added dropwise thereto at a constant rate over 1 hour. After that, the mixture was continuously stirred at 110 ° C. for 2 hours and then cooled to room temperature. Finally, the mixed solution of Part 1-4 was added and stirred.

The solid content of the obtained solution was 63%. When the obtained polymer was analyzed by GPC, the number average molecular weight was 4000.

Synthesis Example 2 First, a mixed solution of the following parts 2-1 to 2-4 was prepared.

(Part 2-1) ST 13g MMA 18g TSMA 52g Butyl methacrylate 16g t-Butylacrylamide 1g 2,2'-azobis (20methylbutyronitrile) 3g (V-produced by Wako Pure Chemical Industries, Ltd. 59) Solvesso 100 17g n-butanol 2g MOA 2g mixed solution (part 2-2) xylene 17g (part 2-3) V-59 0.2g xylene 11g n-butanol 2g mixed solution (part 2-4) MOA 4g Mixed solution of MeOH 2 g Next, in a nitrogen atmosphere, the mixed solution of the part 2-1 was dropped at a constant rate into the part 2-2 heated to 130 ° C. over 4 hours. Next, the mixed solution of Part 2-3 was added dropwise thereto at a constant rate over 0.5 hour. After that, the mixture was continuously stirred at 130 ° C. for 1 hour and then cooled to room temperature. Finally, the mixed solution of part 2-4 was added and stirred.

The solid content concentration of the obtained solution was 61%. When the obtained compound was analyzed by GPC, the number average molecular weight was 3,000.

Examples 1-5 and Comparative Examples 1-5 The polymers obtained in Synthesis Examples 1-2 were blended with the polycarbonate polyols shown in Table 1 or other compounds in the compositions shown in Table 1. Leveling agent (# 1984-50 manufactured by Kusumoto Kasei Co., Ltd.) with respect to the total solid content of each Example or Comparative Example
A mixture of 0.4% and 2% of a mixture of diisopropanolamine / dodecylbenzenesulfonic acid = 3/7 (weight ratio) as a curing catalyst for the component (C) was added. Solvesso this mixture 1
It was diluted with 00 and adjusted to a viscosity of 15 to 20 seconds with a Ford cup to obtain a clear paint for top coat.

[0070] A mild steel sheet that had been degreased and phosphorylated was coated with an epoxyamide-based cationic electrodeposition primer for automobiles and an intermediate coat surfacer as a test piece, and a commercially available acrylic melamine resin coating (silver metallic Base) as a base coat.

Next, the clear coating composition for the top coat was applied wet-on-wet, set for 20 minutes, and then baked at 140 ° C. for 30 minutes.

The dry film thickness was about 15 μm for the base coat and about 50 μm for the top coat clear.

The obtained coating film was evaluated by the following methods. The results are shown in Table 1.

(Acid resistance) The test piece was placed in 1% sulfuric acid at 70 ° C. for 24 hours.
The retention rate (%) of 20 ° gloss after immersion in time is calculated. The higher the retention rate, the better the acid resistance.

(Scratch resistance) A test piece was fixed horizontally, and an abrasive (JIS 8 type loam ± 1.2%, JIS 11 type loam ± 1.2%, kaolin 0.6%, neutral detergent 1.0%, water was placed on the test plate. 96.0
% Mixture), and then a weight (contact surface diameter 5 cm, load 22 g / cm ² ) covered with kraft paper is stroked on the coated surface. The brightness after 0, 20, and 100 strokes is measured with a color difference meter, and the scratch resistance is evaluated by the difference in brightness (ΔL). The smaller ΔL indicates that the scratch resistance is better.

(Pencil hardness) Evaluation is made according to JIS K 5400.

Examples 6 to 14 Paints were prepared in the same manner as in Example 2 except that the amines shown in Table 2 were used instead of the amines used in Example 2.
The viscosity change rate and gel fraction were determined. The results are shown in Table 2.

Example 15 A coating material was prepared in the same manner as in Example 2 except that the curing catalyst shown in Table 2 was used instead of the curing catalyst used in Example 2, and the viscosity change rate and the gel fraction were determined. . The results are shown in Table 2.

Comparative Examples 6 to 7 In place of the curing catalyst used in Example 2, dodecylbenzenesulfonic acid shown in Table 2 was used alone or dioctyl phosphate / 1,8-diazabicyclo [5.4.0] -7 undecene was used. A coating material was prepared in the same manner as in Example 2 except for the above, and the rate of change in viscosity and the gel fraction were determined. The results are shown in Table 2.

(Rate of change in viscosity) The viscosity at 23 ° C. after storage at 50 ° C. was measured by a Ford cup and the measured value was divided by the initial viscosity. A low rate of change in viscosity indicates excellent storage stability.

(Gel Fraction) A free clear film obtained by baking at 140 ° C. for 30 minutes was wrapped in an already precisely weighed 300-mesh stainless steel wire mesh (W ₀ ) and weighed precisely (W ₁ ). This was immersed in acetone for 24 hours for extraction, dried, and precisely weighed (W ₂ ). The gel fraction was calculated according to the following formula. A large gel fraction value close to 100% indicates that the proportion of acetone insoluble matter in the film is high, and the degree of crosslinking is large accordingly.

[0082]

[Equation 1]

[0083]

[Table 1]

[0084]

[Table 2]

From the results shown in Table 1, it is understood that the scratch resistance is improved by adding the polycarbonate polyol as the component (B) to the polymer having a hydrolyzable silyl group as the component (A). Further, the composition of the present invention has excellent acid resistance as compared with the case where polycaprolactone diol is added to the hydrolyzable silyl group-containing polymer of the component (A) or the case where acrylic melamine is used alone. I understand.

Further, from the results shown in Table 2, as a curing catalyst for the component (C), an organotin compound or a substance obtained by blocking a sulfonic acid with an amine has a small rate of change in viscosity, so that the storage stability and curability of one component are You can see that it is excellent.

[0087]

As described in detail above, the composition of the present invention has low toxicity, high solidity, improved balance of acid resistance, scratch resistance, and curability, and provides a superior coating film. Moreover, it is a curable composition for paints having good one-liquid storage stability.

Front page continuation (72) Inventor Hisao Furukawa 4-5-7 Chikushigaoka, Kita-ku, Kobe-shi, Hyogo

Claims (4)

[Claims] 1. A main chain (A) is substantially composed of a vinyl polymer chain, and has at least one silicon atom bonded to a hydrolyzable group at the terminal and / or side chain of the main chain in one molecule. 10-99 parts by weight of a vinyl polymer having a number average molecular weight of 2000 or more and (B) an average of at least one carbonate bond and at least two hydroxyl groups per molecule,
Polycarbonate polyol compound 1 to 90 parts by weight in total
A curable composition for coating composition containing 0.001 to 10 parts by weight of (C) a curing catalyst based on 100 parts by weight. 2. The curing catalyst is such that the sulfonic acid group is blocked with an amine, and the amine is 0.5 per 1 equivalent of the sulfonic acid group.
The composition according to claim 1, which is comprised of about 3.0 equivalents. 3. The composition according to claim 2, wherein the amine is a primary or secondary amine having at least one hydroxyl group in one molecule. 4. The composition according to claim 2, wherein the amine is morpholine.