JPH0770509A - Thermosetting topcoating composition - Google Patents

Abstract

PURPOSE:To obtain a topcoating composition which gives a thermosetting coating film excellent in the balance between the retention of water repellency and tight adhesion in recoating, by mixing a carboxylated acrylic polyol, an acrylic copolymer having a specified alkoxysilyl group, a reactive organopolysiloxane, and an epoxy resin. CONSTITUTION:The composition comprises a carboxylated acrylic polyol, an acrylic copolymer having an alkoxysilyl group of the formula (wherein R<1> is 1-10C alkyl or phenyl; R<2> is H or a monovalent hydrocarbon group selected from 1-10C alkyl, 1-10C aryl and 1-10C aralkyl; and a is 0, 1 or 2), a reactive organopolysiloxane, and an epoxy resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a thermosetting top coating, and more specifically, it is suitably used as a top coating for building exteriors, automobiles, industrial machines, steel furniture, home appliances, plastics members and the like. The present invention relates to a thermosetting composition for top coating composition.

[0002]

2. Description of the Related Art Conventionally, as thermosetting paints, alkyd melamine resin paints,
Acrylic melamine resin paints and epoxy melamine resin paints are known.

Since these paints use volatile melamine as a crosslinking agent for polyols, odor due to by-products has been regarded as a problem.

Further, the above-mentioned coating material using melamine as a cross-linking agent has not yet been satisfactory in terms of water repellency (contact angle of water) retention and weather resistance.

For this reason, recently, particularly in the case of coating materials for automobiles, from the viewpoint of resource saving and energy saving, it is desired to develop maintenance-free water-repellent materials, that is, high-performance paints having excellent water-repellent retention and weather resistance. Has been done.

Therefore, crosslinking is carried out in a completely different manner from the conventional crosslinking method using a polyol and melamine to obtain weather resistance,
A paint comprising a mixture of a polyol and a hydrolyzable silyl group-containing polymer, which gives a cured coating film having excellent physical properties such as chemical resistance and solvent resistance, has been proposed (JP-A-1-1419).
No. 52).

However, this paint has a problem that the balance of the properties of water repellency retention and recoat adhesion is generally poor.

The present invention has been made in view of such circumstances, and an object thereof is to provide a thermosetting composition for a top coating composition capable of giving a cured coating film having an excellent balance of properties of water repellency retention and recoat adhesion. It's about providing things.

[0009]

That is, the composition for thermosetting top coating composition of the present invention comprises (A) an acrylic polyol having a carboxyl group (hereinafter referred to as "carboxyl group-containing acrylic polyol").
Alternatively, it may be simply referred to as “component (A)”. (B) Acrylic copolymer having an alkoxysilyl group represented by the following general formula (hereinafter, “alkoxysilyl group-containing acrylic copolymer” or simply “(B Component)) (C) Reactive organopolysiloxane (hereinafter also simply referred to as "component (C)") and (D) epoxy resin (hereinafter also simply referred to as "component (D)") It is a thing.

[0010]

[Chemical 2] (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms.
A monovalent hydrocarbon group selected from the group consisting of aralkyl groups, and a is 0, 1 or 2. ).

(A) Carboxyl Group-Containing Acrylic Polyol The component (A) in the present invention is for causing the cured product after baking to exhibit various physical properties such as hardness and solvent resistance. Since the main chain is substantially composed of an acrylic copolymer, the cured product has excellent weather resistance, chemical resistance, water resistance and the like.

The carboxyl group-containing acrylic polyol that can be used in the present invention includes, for example, hydroxyl group-containing vinyl polymerizable compound [a1], carboxyl group-containing vinyl polymerizable compound [a2], (meth) acrylic acid (acrylic acid And the meaning of methacrylic acid, the same shall apply hereinafter) [a
3] and the like are obtained by copolymerization.

Examples of the hydroxyl group-containing vinyl-based polymerizable compound [a1] in this case include 2-hydroxyethyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. Hydroxyethyl vinyl ether, N
-Methylol (meth) acrylamide, Aronix 5700, 4-hydroxystyrene manufactured by Toagosei Kagaku Kogyo Co., Ltd., HE-10, HE-20 manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.
HP-10 and HP-20 (all of which are acrylic acid ester oligomers having a hydroxyl group at the terminal), NOF CORPORATION Blemmer PP series (polypropylene glycol methacrylate), Blemmer PE series (polyethylene glycol monomethacrylate), Blemmer PEP series. (Polyethylene glycol polypropylene glycol methacrylate), Blemmer AP-4
00 (polypropylene glycol monoacrylate),
Blemmer AE-350 (polyethylene glycol monoacrylate), Blemmer NKH-5050 (polypropylene glycol polytrimethylene monoacrylate) and Blemmer GLM (glycerol monomethacrylate), ε-obtained by reacting a vinyl compound having a hydroxyl group with ε-caprolactone. Examples thereof include caprolactone-modified hydroxyalkyl vinyl-based monomers.

Among them, the ε-caprolactone-modified hydroxyalkylvinyl-based monomer is preferable because it can impart more excellent impact resistance and flexibility to the coating film.

A typical example of such an ε-caprolactone-modified hydroxyalkyl vinyl monomer is a vinyl monomer represented by the following general formula.

[0016]

[Chemical 3] (In the formula, R is a hydrogen atom or a methyl group, and n is an integer of 1 or more.).

Commercially available products of the vinyl type monomer represented by the above formula are Placcel FA-1 manufactured by Daicel Corporation.
(R = H, n = 1), the same Placel FA-4 (R
= H, n = 4), the same Placcel FM-1 (R = C)
H _3, n = 1), the Placcel FM-4 (R = C
H ₃ , n = 4), TONE M-100 manufactured by UCC.
(R = H, n = 2) and the same TONE M-201 (R
= CH ₃ , n = 1) and the like.

These hydroxyl group-containing vinyl-based polymerizable compounds may be used alone or in combination of two or more as required.

Specific examples of the carboxyl group-containing vinyl-based polymerizable compound [a2] include α, β-of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and the like.
A half ester of an ethylenically unsaturated carboxylic acid or an anhydride thereof and a linear or branched alcohol having 1 to 20 carbon atoms can be mentioned.

The (meth) acrylic acid derivative [a3] copolymerizable with the hydroxyl group-containing vinyl polymerizable compound is not particularly limited, and specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate and n. -Butyl (meth) acrylate, isobutyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (Meth) acrylonitrile, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth)
Acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (meth)
Acrylamide, N, N-dimethyl (meth) acrylamide, N-methylacrylamide, acryloylmorpholine, N-methylol (meth) acrylamide, AS-6, AN which is a macromonomer manufactured by Toagosei Co., Ltd.
-6, AA-6, AB-6, AK-5, hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids such as hydroxyalkyl esters of (meth) acrylic acid, and phosphoric acid or phosphoric acid esters Examples thereof include a phosphoric acid ester group-containing vinyl compound which is a condensation product with and a (meth) acrylate having a urethane bond or a siloxane bond.

The carboxyl group-containing acrylic polyol as the component (A) has a portion formed by urethane bonds or siloxane bonds in the main chain within a range not exceeding 50% by weight (hereinafter abbreviated as "%"). May include,
A portion derived from a monomer other than the (meth) acrylic acid derivative may be included.

There is no limitation on the monomers other than the (meth) acrylic acid derivative, and specific examples thereof include styrene and α-
Aromatic hydrocarbon vinyl compounds such as methylstyrene, chlorostyrene, styrenesulfonic acid and vinyltoluene; vinyl esters and vinyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; amino groups such as vinyl pyridine and aminoethyl vinyl ether Vinyl compounds containing amide groups such as itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone; methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene , Isoprene, fluoroolefin maleimide, N-vinyl imidazole, vinyl sulfonic acid, and other vinyl compounds.

As a method for synthesizing the component (A), a solution polymerization method using a peroxide radical initiator such as t-butylperoxyacetate or an azo radical initiator such as azobisisobutyronitrile, It is preferable because it can be easily synthesized.

In the solution polymerization method, n-
Dodecyl mercaptan, t-dodecyl mercaptan, n
The molecular weight may be adjusted using a chain transfer agent such as -butyl mercaptan. The solvent used for solution polymerization is not particularly limited as long as it is a non-reactive solvent with respect to raw material monomers and the like.

The component (A) is, for example, heptane,
A non-aqueous dispersion type in which insoluble polymer particles are dispersed in a non-polar organic solvent such as pentane may be used.

The molecular weight of the component (A) is not particularly limited, but the physical properties of the cured coating film such as durability expected from the curable composition of the present invention (hereinafter referred to as "coating film physical properties"). The number average molecular weight is preferably 1,500 to 40,000, more preferably 3,000 to 25,000.

The component (A) must have a sufficient number of hydroxyl groups that can be crosslinked, and has a hydroxyl value of 10 to 300 mgKOH / g in terms of strength and durability.
Are preferred, and those of 30 to 150 mg KOH / g are more preferred. Moreover, the acid value is 5 to 120 m.
gKOH / g is preferred, 10-80 mgK
More preferably OH / g, 20 to 60 mg
More preferably KOH / g. Acid value is 5mg
If it is less than KOH / g, the crosslinking of the epoxy resin is insufficient, and if it exceeds 120 mgKOH / g, the storage stability of the composition is lowered.

As the component (A), one type may be used alone, or two or more types may be used in combination.

(B) Alkoxysilyl Group-Containing Acrylic Copolymer The component (B) in the present invention has at least one, preferably two or more alkoxysilyl groups represented by the following general formula in one molecule. is there. If the average number of alkoxysilyl groups in one molecule is less than 1, the solvent resistance of the resulting coating film will be poor.

[0030]

[Chemical 4] (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms.
A monovalent hydrocarbon group selected from the group consisting of aralkyl groups, and a is 0, 1 or 2. ).

The alkoxysilyl group represented by the above formula is
It may be contained at the end of the main chain in the component (B),
It may be contained in the side chain, or may be contained in both the end of the main chain and the side chain.

When R ¹ has more than 10 carbon atoms, the hydrolysis reactivity of the alkoxysilyl group is lowered.

Specific examples of R ¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Examples include isobutyl group and phenyl group.

Specific examples of the alkyl group for R ² include the same alkyl groups as those mentioned in the description of R ¹ , and specific examples of the aryl group include a phenyl group and an aralkyl group. A specific example is a benzyl group.

Specific examples of the alkoxysilyl group represented by the above formula include alkoxysilyl groups contained in the alkoxysilyl group-containing monomers (see [Chemical Formula 5] to [Chemical Formula 6]) described later.

Since the main chain of the component (B) is substantially composed of an acrylic copolymer, the resulting cured product has weather resistance,
It has excellent chemical resistance and water resistance. Moreover, since the alkoxysilyl group is directly bonded to the carbon atom, the cured product has excellent water resistance, alkali resistance, acid resistance, and the like.

The number average molecular weight of the component (B) is preferably in the range of 1,000 to 30,000, from the viewpoint of the physical properties of the coating film obtained from the thermosetting composition for top coating composition of the present invention.
The range of 000 to 25,000 is more preferable.

If the number average molecular weight is less than 1,000, the problem of deterioration of curability tends to occur.
When it exceeds 50,000, the problem that the storage stability is lowered tends to occur.

The alkoxysilyl group-containing acrylic copolymer (B) can be obtained, for example, by copolymerizing acrylic acid, methacrylic acid, a derivative thereof [b1] or the like with an alkoxysilyl group-containing monomer [b2]. .

The acrylic acid or methacrylic acid derivative [b1] is not limited to the foil, and specific examples thereof include
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) Acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (meth) acrylonitrile, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α -Ethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N,
N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, Aronix M-570 manufactured by Toagosei Co., Ltd.
0, AS which is a macromonomer manufactured by Toagosei Chemical Industry Co., Ltd.
-6, AN-6, AA-6, AB-6, AK-5, Placcel FA-1, Placcel manufactured by Daicel Corp.
FA-4, Placcel FM-1, Placce
1 FM-4, a phosphoric acid ester which is a condensation product of hydroxyalkyl ester of α, β-ethylenically unsaturated carboxylic acid such as hydroxyalkyl ester of (meth) acrylic acid and phosphoric acid or phosphoric acid ester Examples thereof include a group-containing vinyl compound and a (meth) acrylate containing a urethane bond or a siloxane bond.

The above alkoxysilyl group-containing monomer [b
2] is not particularly limited except that it has a polymerizable double bond, and specific examples thereof include compounds represented by the following formula. In addition, (meth) acrylate having a terminal alkoxysilyl group via a urethane bond or a siloxane bond is also included.

[0042]

[Chemical 5]

[0043]

[Chemical 6]

The proportion of the portion formed by the alkoxysilyl group-containing monomer [b2] in the component (B) is 5 to 90.
% Is preferable in terms of curability of the composition and physical properties of the coating film, and more preferably 11 to 70%.

The component (B) may contain a part formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50%, and a monomer [b3 other than the (meth) acrylic acid derivative is included. ] The part derived from] may be included.

The monomer [b3] other than the (meth) acrylic acid derivative is not particularly limited, and specific examples thereof include
Aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene and vinyltoluene; unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid, and salts thereof ( Unsaturation such as alkali metal salts, ammonium salts, amine salts, etc., their acid anhydrides (maleic anhydride, etc.), or diesters or half esters of them with linear or branched alcohols having 1 to 20 carbon atoms Carboxylic acid ester; Vinyl acetate or vinyl compound such as vinyl acetate, vinyl propionate, diallyl phthalate; Amino group-containing vinyl compound such as vinyl pyridine, aminoethyl vinyl ether; Itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide , N-bi Amido group-containing vinyl compounds such as rupyrrolidone; 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinyl imidazole, vinyl sulfonic acid, etc. And other vinyl compounds. (B)
The components are, for example, JP-A-54-36395 and JP-A-
Although it can be produced by the method disclosed in JP-A No. 7-36109, JP-A No. 58-157810, etc., an azo radical initiator such as azobisisobutyronitrile is used from the viewpoint of easiness of synthesis. Most preferably by a solution polymerization method.

During this solution polymerization, if necessary, n-
Dodecyl mercaptan, t-dodecyl mercaptan, n
-Butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane,
The molecular weight can be adjusted by using a chain transfer agent such as a compound represented by the following [Chemical formula 7]. Also,
Using a chain transfer agent having an alkoxysilyl group in the molecule, for example γ-mercaptopropyltrimethoxysilane,
It is preferable to continuously replenish the amount consumed during the progress of the reaction because it is possible to introduce an alkoxysilyl group at the terminal of the silyl group-containing acrylic copolymer together with the adjustment of the molecular weight.

[Chemical 7]

As the polymerization solvent in the case of the above solution polymerization method, hydrocarbons (toluene, xylene, n-hexane, cyclohexane etc.), acetic acid esters (ethyl acetate, butyl acetate etc.), ethers (ethylene glycol monoethyl) Ether, ethylene glycol mono-n-
Butyl ether, ethylene glycol monoethyl ether acetate), ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, acetone, etc.) can be used without particular limitation as long as they are non-reactive solvents to the raw material monomers. .

As the component (B), one type may be used alone, or two or more types may be used in combination. Although there is no particular limitation on the mixing ratio of the above-mentioned (A) component and (B) component, the (A) component / (B) component ratio is 9/1 to 1 by weight.
It is preferably in the range of / 9, and more preferably in the range of 8/2 to 2/8.

When the above component ratio exceeds 9/1, the water resistance of the coating film obtained from the composition of the present invention tends to decrease, and when it is 1/9 terminal, the component (A) is blended. The effect of does not tend to be sufficiently obtained.

(C) Reactive Organopolysiloxane The component (C) in the present invention imparts water repellency to the coating film,
It is a component used for maintaining water repellency (for example, water repellency after a weather resistance test) and preventing adhesion of contaminants such as dust, and the like, and is compatible with components (A) and (B). As long as it is soluble, it can be used without particular limitation.

The component (C) may have any of linear, branched, reticulated and cyclic structures, and the organo group (organic group) may be an alkyl group (methyl group, ethyl group, propyl group). Group, butyl group, hexyl group, etc.), alkenyl group, aryl group, allyl group, phenyl group and the like. Among them, those having an organo group such as a methyl group, a vinyl group and a phenyl group are practically advantageous in that they are industrially produced and are inexpensive.

Examples of the reactive functional group include silanol group, alkoxysilyl group, alcoholic hydroxyl group, glycidyl group, amino group, mercapto group, carboxyl group, amide group, vinyl group and (meth) acryloxy group. Of these, a silanol group, an alkoxysilyl group, and an alcoholic hydroxyl group represented by the following formula [Formula 8] are preferable.

[Chemical 8]

The number of reactive functional groups is preferably one or more in one molecule of the reactive organopolysiloxane (C).

The molecular weight of the component (C) can be appropriately selected within a range where it is compatible with the components (A) and (B), and it cannot be said unconditionally. However, as the molecular weight increases, the compatibility becomes higher. Tends to decline.

The number of silicon atoms contained in one molecule is preferably 2 to 300,
The number of 100 is more preferable, and the number of 3-50 is particularly preferable.

Specific examples of the reactive organopolysiloxane (C) include the following.

Examples of those having an alkoxysilyl group as a reactive functional group include those represented by the following [Chemical Formula 9] and [Chemical Formula 10].

[Chemical 9]

[0059]

[Chemical 10]

Examples of those having a silanol group as a reactive functional group include those represented by the following [Chemical formula 11].

[Chemical 11]

Examples of compounds having other reactive functional groups include those represented by the following [Chemical Formula 12].

[Chemical 12]

[0062]

[Chemical 13]

Examples of the compounds copolymerizable with the component (A) or the component (B) include those represented by the following [Chemical formula 14] and [Chemical formula 15].

[Chemical 14]

[0064]

[Chemical 15]

As the component (C), one type may be used alone, or two or more types may be used in combination. The mixing ratio of the component (C) is such that the total solid content of the components (A) and (B) is 100.
It is usually 0.01 to 100 parts, and preferably 0.05 to 50 parts by weight (hereinafter, abbreviated as "part").
It is a department. When the blending ratio is less than 0.05 part, water repellency and the like cannot be sufficiently exhibited, and when it exceeds 50 parts, problems such as compatibility and cissing occur.

(D) Epoxy Resin As the component (D) that can be used in the present invention, epichlorohydrin-bisphenol A type epoxy resin, epichlorohydrin-bisphenol F type epoxy resin, tetrabromobisphenol A glycidyl ether and other flame retardant type Epoxy resin, novolac type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, p-oxybenzoic acid glycidyl ether ester type epoxy resin, m-aminophenol type epoxy resin,
Diaminodiphenylmethane-based epoxy resin, urethane-modified epoxy resin, various alicyclic epoxy resins, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, triglycidyl isocyanurate, polyalkylene glycol diglycidyl ether, glycerin, etc. Examples include polyhydric alcohol glycidyl ethers, hydantoin type epoxy resins, epoxidized unsaturated polymers such as petroleum resins, etc., but are not limited to these, and commonly used epoxy resins Can be used. Among these epoxy resins, especially the formula

[Chemical 16] It is preferable that at least two epoxy groups represented by are contained in the molecule because they have high reactivity during curing and the cured product easily forms a three-dimensional network.

The number average molecular weight of the component (D) is 150 to 1.
The range of 10,000 is preferable, and the range of 170 to 5,000 is more preferable.

When the number average molecular weight is less than 150, the problem of low hardness is apt to occur, and 10,000
When it exceeds 0, the problem that other compatibility is poor is likely to occur.

The mixing ratio of the component (D) is 1 to 1 with respect to 100 parts of the total resin solid content of the components (A) and (B).
00 parts are preferable, 1 to 50 parts are more preferable, and 5 parts
30 parts is more preferred. If the blending ratio is less than 1 part, the effect of developing recoat adhesion is small, and if it exceeds 100 parts, problems occur in terms of weather resistance, storage stability and the like.

The effect of the present invention is to apply the composition of the present invention to an article to be coated, and thereby to obtain a cured product (coating film) having a good balance of water repellency retention and recoat adhesion on the article.
Which is formed by the four components of the component (A), the component (B), the component (C) and the component (D).

That is, the component (A), the component (B) and the component (C)
The composition composed of the three-component system has excellent water-repellent retention, but has a problem in recoat adhesion. However, by blending this with the epoxy resin (D), not only the recoat adhesion is improved, but also the water repellency retention can be enhanced.

In addition, in order to shorten the curing time, a curing catalyst may be added to the thermosetting composition for top coating composition of the present invention.

Specific examples of the curing catalyst in that case include dibutyltin dilaurate, dibutyltin dimaleate,
Dioctyl tin dilaurate, dioctyl tin dimaleate, polymers of dioctyl tin dimaleate, organotin compounds such as tin octylate; phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl Phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate,
Phosphoric acid or phosphoric acid ester such as didecyl phosphate; propylene oxide, butylene oxide, cyclohexene oxide, glycidyl methacrylate, glycidol, acryl glycidyl ether, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, a compound represented by the following [Chemical formula 17], epoxy compounds such as Cardura E manufactured by Yuka Shell Epoxy Co., Epicoat 828, and Epicoat 1001 and phosphoric acid and / or monoacidic phosphorus. Addition reaction product with acid ester; Organic titanate compound; Organoaluminum compound such as tris (ethylacetoacetate) aluminum, tris (acetylacetonato) aluminum; Tetrabutyl Zirconate, tetrakis (acetylacetonato) zirconium, tetraisobutyl zirconate, Butokishitorisu (acetylacetonate)
Organozirconium compounds such as zirconium; maleic acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, succinic acid, phthalic acid, trimellitic acid,
Acid compounds such as pyromellitic acid, acid anhydrides thereof, and paratoluenesulfonic acid; amines such as hexylamine, di-2-ethylhexylamine, N, N-dimethyldodecylamine, dodecylamine; these amines and acidic phosphoric acid Mixtures or reactants with esters, for example
NACURE 5225 and NACURE made by KING INDUSTRIES (King Industries)
5543, NACURE 5925; alkaline compounds such as sodium hydroxide and potassium hydroxide.

[Chemical 17]

Among the curing catalysts exemplified above, an organotin compound, an acidic phosphoric acid ester, a mixture or a reaction product of an acidic phosphoric acid ester and an amine, a saturated or unsaturated polyvalent carboxylic acid or an acid anhydride thereof, a reactivity Silicon compounds,
Organic titanate compounds, organoaluminum compounds, organozirconium compounds or mixtures of two or more thereof are preferred because of their high activity.

The above curing catalysts may be used alone or in combination of two or more. The compounding amount of the curing catalyst is not particularly limited, but is usually preferably in the range of 0.1 to 20 parts, and preferably 0.1 to 10 parts with respect to 100 parts of the total amount of the resin solids of the components (A) and (B). A range is more preferable. If the compounding amount of the curing catalyst is less than 0.1 part, the curability tends to decrease, and if it exceeds 20 parts, the appearance of the coating film tends to deteriorate, so both are not preferable.

Further, the thermosetting composition of the present invention is usually used by blending a solvent. The solvent that can be used is not particularly limited as long as it is a non-reactive solvent, and specific examples thereof include general paints, aliphatic hydrocarbons used in coating agents, halogenated hydrocarbons, Examples thereof include alkyl alcohols, ketones, esters, ethers, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, ester ethers and the like. Of these, alkyl alcohols are preferable because the storage stability of the composition is improved.

As the above-mentioned alkyl alcohols, those having an alkyl group having 1 to 10 carbon atoms are preferable.
Methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol,
Examples thereof include t-butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, octyl alcohol and ethylene glycol monoether.

The solvent in the present invention may be used alone or in combination of two or more.

The amount of alcohol as a solvent is not particularly limited, but is preferably 50 parts or less and more preferably 10 parts or less with respect to 100 parts of the total amount of the resin solids of the components (A) and (B).

Generally, the blending amount of the solvent varies depending on the molecular weights of the component (A) and the component (B) and the composition ratio of both components, and is adjusted according to the solid content concentration and viscosity required for practical use.

Further, in order to ensure storage stability without problems for repeated use over a long period of time, it is preferable to add a dehydrating agent to the thermosetting composition of the present invention.

Specific examples of dehydrating agents that can be used include methyl orthoformate, ethyl orthoformate, methyl orthoacetate,
Examples thereof include hydrolyzable ester compounds such as ethyl orthoacetate, methyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, methylsilicate and ethylsilicate.

The dehydrating agent may be added before the polymerization of the component (B), after the polymerization, or during the polymerization.

The amount of the dehydrating agent added is not particularly limited,
Total amount of resin solids of component (A) and component (B) 100
The amount is preferably 100 parts or less, more preferably 50 parts or less.

By using the above-mentioned alkyl alcohol in combination with a dehydrating agent, the storage stability can be remarkably improved.

In the composition for thermosetting top coating composition of the present invention,
Depending on the application, diluents, pigments such as extender pigments, UV absorbers, light stabilizers, antisettling agents, leveling agents, and other additives; nitrocellulose, cellulose acetate butyrate, and other fibrin compounds; melamine resins, vinyl chloride Resins, resins such as chlorinated polypropylene, chlorinated rubber, polyvinyl butyral; fillers and the like may be added.

After applying the composition for a thermosetting top coating composition of the present invention to an object to be coated by various coating methods such as dipping, spraying and brush coating, it is usually 30 ° C. or higher, preferably 55 to 55 ° C. By curing at 350 ° C., it is possible to form a cured coating film having excellent water repellency retention, recoat adhesion, durability and the like on the surface of the article to be coated.

[0088]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications may be made without departing from the scope of the invention. Is possible.

Synthesis Example 1 (carboxyl group-containing acrylic
Synthesis of Polyol (A-1)) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction pipe, and a dropping funnel, butyl acetate 31.3
And 9.5 parts of xylene as a polymerization solvent were charged, and the temperature of the mixture was raised to 110 ° C. while introducing nitrogen gas through a nitrogen gas introducing pipe. Then, a mixture having the composition shown in the following [Table 1] was added to the same table. It was added dropwise at a constant rate from the dropping funnel at the indicated ratio over 5 hours.
After the dropping of the above mixture, 0.2 parts of 2,2'-azobisisobutyronitrile and 3.8 parts of toluene were added dropwise over 1 hour. Then, the mixture is reacted at 110 ° C. for 2 hours and cooled, xylene is added to the resin solution to adjust the solid content concentration to 60%, and the carboxyl group-containing acrylic polyol (A
-1) was obtained. Hydroxyl value of this polymer (A-1) (mg
KOH / g solid) is 112, and the number average molecular weight is 1
0,500, acid value (mgKOH / g solid) is 5
It was 5.

Synthesis Example 2 (carboxylic group-containing acrylic type)
Synthesis of Polyol (A-2)) In the same reaction vessel as in Synthesis Example 1, 31.3 parts of butyl acetate,
After 9.5 parts of xylene was charged as a polymerization solvent and the temperature was raised to 110 ° C. while introducing nitrogen gas through a nitrogen gas introduction tube, a mixture having the composition shown in the following [Table 1] was added at the ratio shown in the same table. The dropping was performed at a constant rate over 5 hours from the dropping funnel. After the dropping of the above mixture, 0.2 parts of 2,2'-azobisisobutyronitrile and 3.8 parts of toluene were added dropwise over 1 hour. Then, the mixture was reacted at 110 ° C. for 2 hours and cooled, and xylene was added to the resin solution to adjust the solid content concentration to 60% to obtain a carboxyl group-containing acrylic polyol (A-2). The hydroxyl value of this polymer (A-2) (mgKOH /
g solid) is 112, and the number average molecular weight is 10,20.
The acid value was 0 and the acid value (mgKOH / g solid) was 31.

Synthesis Example 3 (Acrylate containing an alkoxysilyl group
Synthesis of Polymer (B-1)) A reaction vessel similar to that used in Synthesis Example 1 was charged with 45.9 parts of xylene as a polymerization solvent and introduced at 110 ° C. while introducing nitrogen gas.
After the temperature was raised to 1, the mixture having the composition shown in the following [Table 1] was added dropwise at a rate shown in the same table from the dropping funnel at a constant rate over 5 hours. After the dropping of the above mixture, 0.5 parts of 2,2'-azobisisobutyronitrile and 5 parts of toluene were added dropwise at a constant rate over 1 hour. Then, the mixture was aged at 110 ° C. for 2 hours and then cooled, and xylene was added to the resin solution to adjust the solid content concentration to 60.
% To give an alkoxysilyl group-containing acrylic copolymer (B-1). The number average molecular weight of this polymer (B-1) was 6,100.

Synthesis Example 4 (alkoxysilyl group-containing acrylate)
Synthesis of Polymer (B-2)) A reactor similar to that used in Synthesis Example 1 was charged with 45.9 parts of xylene as a polymerization solvent at 110 ° C. while introducing nitrogen gas.
After the temperature was raised to 1, the mixture having the composition shown in the following [Table 1] was added dropwise at a rate shown in the same table from the dropping funnel at a constant rate over 5 hours. After the dropping of the above mixture, 0.5 parts of 2,2'-azobisisobutyronitrile and 5 parts of toluene were added dropwise at a constant rate over 1 hour. Then, after aging at 110 ° C. for 2 hours and then cooling, xylene was added to the resin solution to adjust the solid content concentration to 60%.
To prepare an alkoxysilyl group-containing acrylic copolymer (B-2). The number average molecular weight of this polymer (B-2) was 6,000.

[0093]

[Table 1]

Examples 1 to 8 and Comparative Examples 1 to 4 Components (A component to D) shown in the following [Table 2] and [Table 3]
Ingredients) were mixed in the resin solid content ratio shown in the table to prepare a top coat clear paint. 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) was applied on it. After that, in a wet-on-wet system, tinuvin 900 (a benzotriazole-based ultraviolet absorber manufactured by Ciba-Geigy) and tinuvin 292 were added to the respective top coat clear paints.
(Hindered amine light stabilizer manufactured by Ciba Geigy)
Is added to 100 parts of resin solids, and diluted with xylene to a sprayable viscosity.
Baking for 30 minutes at 0 ° C. At this time, the dry film thickness of the base coat was about 15 μm, and the dry film thickness of the top coat clear paint was about 30 μm.

The water contact angle, recoat adhesion, water resistance and acid resistance of each of the obtained coated products were measured by the methods described below. The results are shown in [Table 2].
And [Table 3].

Contact Angle A contact angle FAC contact angle meter CA-P (manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle of each coated product with water after the initial and weather resistance tests. The weather resistance test was conducted by using Yubucon manufactured by Atlas Co., Ltd., and was irradiated with ultraviolet rays at 70 ° C. for 8 hours.
Water agglomeration (dark) at 50 ° C for 4 hours as one cycle,
Accelerated tests were conducted for a total of 1400 hours.

Recoat Adhesiveness Each of the above-mentioned coated products was further coated with an acrylic melamine resin coating (silver metallic base), then the above-mentioned top coating clear coating was coated by a wet-on-wet system, and baked at 140 ° C. for 30 minutes. . The coated article after baking was tested by a cross cut test method according to JIS K5400. 25/25 is 10 points and 0/25
Was evaluated as 0 point.

Using a test piece that had been subjected to water-resistant recoating, it was immersed in warm water at 40 ° C. for 10 days, taken out, and then examined for changes in appearance and adhesion. (Evaluation Criteria) Appearance When there is no luster, whitening or blister:
○ When luster and bleaching are slightly observed: △ When luster and bleaching are remarkable: × Adhesion Adhere to the recoat adhesion test method.

About 0.2 ml of acid-resistant 40% H ₂ SO ₄ was spotted and heated at 60 ° C. for 30 minutes, and then the state of the coating film was examined. (Evaluation Criteria) No abnormality: ○ Slightly reduced gloss, spots are observed: △ When blister or dissolution is observed in the coating film: ×.

[0100]

[Table 2]

[0101]

[Table 3]

From [Table 2] and [Table 3], it can be seen that the composition for thermosetting top coating composition according to the present invention shows a small reduction in contact angle even after the weather resistance test and is excellent in recoat adhesion. I understand.

[0103]

EFFECTS OF THE INVENTION The thermosetting composition for a top coating composition according to the present invention exhibits excellent unique effects such as excellent balance of physical properties such as retention of water repellency and recoat adhesion.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C09D 143/04 PGL 183/04 PMU

Claims (6)

[Claims] 1. (A) Acrylic polyol having a carboxyl group (B) Acrylic copolymer having an alkoxysilyl group represented by the following general formula (C) Reactive organopolysiloxane, and (D) Epoxy type A thermosetting composition for a top coating, comprising a resin. [Chemical 1] (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, a phenyl group, R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms.
A monovalent hydrocarbon group selected from the group consisting of aralkyl groups, and a is 0, 1 or 2. ) 2. The hydroxyl value of the component (A) is 10 to 300.
mgKOH / g and number average molecular weight of 1,500
It is -40,000, The composition for thermosetting top coat paints of Claim 1 characterized by the above-mentioned. 3. The component (B) contains 5 to 9 alkoxysilyl group-containing monomer units each having a polymerizable double bond and an alkoxysilyl group in the molecule.
The thermosetting composition for topcoat according to claim 1 or 2, which is a copolymer containing 0% by weight. 4. The thermosetting topcoat according to claim 1, wherein the component (C) is a compound having a reactive functional group at the terminal and / or side chain. Paint composition. 5. The thermosetting topcoat paint according to any one of claims 1 to 4, wherein the component (D) is a resin having at least two epoxy groups in the molecule. Composition. 6. The proportion of the component (D) used is such that the total resin solid content of the component (A) and the component (B) is 1
It is 1-100 weight part with respect to 00 weight part, The composition for thermosetting top coating materials of any one of Claims 1-5 characterized by the above-mentioned.