JPH0827413A - Curing composition for finishing coating - Google Patents

Abstract

PURPOSE:To obtain a curing composition composed of a vinyl copolymer having a hydrolyzable silyl group bound to carbon atom and a hydroxyl group at the terminal or side chain, an amino polymer and a hardening catalyst, offering a good balance of curability and storage stability and excellent in acid resistance. CONSTITUTION:This composition is composed of (A) 100 pts.wt. of a vinyl copolymer having a main chain consisting of a vinyl copolymer chain and one or more than one of hydrolyzable silyl group bound to carbon atom expressed by the formula (R<1> is H or a 1-10C alkyl; R<2> is H, a 1-10C alkyl, an aryl, etc.; R<3> is a l-6C alkyl or a l-10C alkoxy; a=0-2; b=0-10) at the terminal of the main chain and/or at side chain and further having one or more than one of alcoholic hydroxyl group at the terminal of the main chain and/or side chain, and having an alcoholic hydroxy value of 400-2000g/mol, (B) 0.01-5 pts.wt. of an amino resin and (C) a hardening catalyst in an amount of 0.001-10 pts.wt. based on 100 pts.wt. of the total of components A and B. The objective composition offers a good balance of curabillty and storage stability and is excellent in high temperature acid resistance.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a curable composition for a top coat. More specifically, for example, it can be suitably used for top coatings used for automobiles, industrial machines, steel furniture, interior and exterior of buildings, home appliances, plastics, etc., and has excellent water resistance, appearance, and thermosetting property. The present invention relates to a curable composition for a topcoat paint, which exhibits storage stability and the like and has excellent acid resistance, and can be suitably used especially for a topcoat paint for automobiles.

[0002]

2. Description of the Related Art Conventionally, paints containing melamine resins such as alkyd melamine resins and acrylic melamine resins have been mainly used for painting automobiles, interior and exterior of buildings, industrial machines, steel furniture, plastics, etc. ,
Such a melamine resin has a problem that harmful formalin is generated at the time of curing and the cured coating film is inferior in acid resistance, so that it is attacked by acid rain.

In particular, the problem of acid rain caused by air pollution in recent years has become serious, and there are phenomena such as etching, whitening, and stains on the coating film.

In order to solve the above-mentioned problems, the present inventors have found that a vinyl-based copolymer having a hydrolyzable silyl group or a blend of a vinyl-based copolymer having a hydrolyzable silyl group and an acrylic polyol. System, as a result of studying the use of a copolymer such as a vinyl-based monomer having a hydrolyzable silyl group and a vinyl-based monomer having an alcoholic hydroxyl group in a coating material, when these are used, It has been found that a coating having excellent acid resistance and weather resistance can be obtained, and a patent application has been filed first (Japanese Patent Laid-Open No. 63-132).
977, JP-A-2-289642, JP-A-6-136324, etc.).

A vinyl copolymer having a hydrolyzable silyl group, a blend system of a vinyl copolymer having a hydrolyzable silyl group and an acrylic polyol, and a vinyl monomer having a hydrolyzable silyl group. The characteristic of the copolymer of a vinyl monomer having an alcoholic hydroxyl group is that a hydrolyzable silyl group and an alcoholic hydroxyl group form a stable siloxane bond or a siloxy bond and cure, so that an acrylic melamine resin or It is possible to form a coating film having excellent acid resistance and weather resistance as compared with the case of using a melamine resin such as an alkyd melamine resin. Also,
The hydrolyzable silyl group has the general formula (I):

[0006]

Embedded image

(In the formula, R ¹ is a hydrogen atom or a carbon number of 1 to
10 alkyl groups, R ² is a hydrogen atom or 1 to 1 carbon atoms
0 alkyl group, a monovalent hydrocarbon group selected from the group consisting of aryl and aralkyl groups, R ³ is 1 to carbon atoms
An alkyl group of 6 or an alkoxyl group of 1 to 10 carbon atoms, provided that two R ^{3 s} are not the same, a is 0 to 2 and b is an integer of 0 to 10) In the meanwhile, since the silyl group is introduced into the main chain of the copolymer through the Si—C bond, it is possible to form a coating film having excellent acid resistance and weather resistance.

[0008]

However, a vinyl polymer homopolymer having a hydrolyzable silyl group and an alcoholic hydroxyl group in the same molecule does not always have sufficient curability, appearance and storage stability. Further, recently, the demand for acid resistance has increased, and the acid resistance at high temperatures is not sufficiently satisfied.

The inventors of the present invention have conducted extensive studies to obtain a curable composition for top coating composition which has a good balance of curability, appearance and storage stability and which has excellent acid resistance at high temperatures. The invention was completed.

[0010]

According to the present invention, the main chain (A) consists essentially of a vinyl copolymer chain, and the main chain ends and / or side chains have the general formula (I):

[0011]

Embedded image

(In the formula, R ¹ is a hydrogen atom or a carbon number of 1 to
10 alkyl groups, R ² is a hydrogen atom or 1 to 1 carbon atoms
0 alkyl group, a monovalent hydrocarbon group selected from the group consisting of aryl and aralkyl groups, R ³ is 1 to carbon atoms
A hydrolyzable silyl group represented by an alkyl group of 6 and an alkoxyl group of 1 to 10 carbon atoms, provided that two R ^{3 s} are not the same, a is 0 to 2 and b is an integer of 0 to 10). It has at least one group in the molecule, and has at least one alcoholic hydroxyl group at the main chain terminal and / or side chain.
Have individual, alcoholic hydroxyl equivalent is 400-2000g
100 parts by weight of vinyl copolymer (weight part, the same shall apply hereinafter) (B) 0.01 to 5 parts of amino resin and (C) curing catalyst 100 parts of total amount of component (A) and component (B) To 0.001 to 10 parts by weight of the curable composition for top coating composition.

[0013]

EXAMPLES The main chain used in the present invention consists essentially of a vinyl copolymer chain, and the main chain ends and / or side chains have the general formula (I):

[0014]

[Chemical 4]

(Wherein R ¹ is a hydrogen atom or a carbon number of 1 to
10 alkyl groups, R ² is a hydrogen atom or 1 to 1 carbon atoms
0 alkyl group, a monovalent hydrocarbon group selected from the group consisting of aryl and aralkyl groups, R ³ is 1 to carbon atoms
A hydrolyzable silyl group represented by an alkyl group of 6 and an alkoxyl group of 1 to 10 carbon atoms, provided that two R ^{3 s} are not the same, a is 0 to 2 and b is an integer of 0 to 10). It has at least one group in the molecule, and has at least one alcoholic hydroxyl group at the main chain terminal and / or side chain.
Have individual, alcoholic hydroxyl equivalent is 400-2000g
/ Mol vinyl-based copolymer (hereinafter, copolymer (A)
Is a component that serves as a base resin of the curable composition for top-coat paint of the present invention (hereinafter referred to as a curable composition).

As described above, since the main chain of the copolymer (A) consists essentially of the vinyl copolymer chain, it is formed from the curable composition of the present invention prepared using the copolymer (A). The coated film has excellent weather resistance and chemical resistance.

The term “substantially” means that the proportion of the vinyl-based copolymer in the copolymer chain is 50% or more, and further 80%.
That is all.

Since the copolymer (A) has a hydrolyzable silyl group introduced into the main chain terminal and / or side chain of the copolymer chain through a Si--C bond, the curable composition obtained is The objects have excellent acid resistance and weather resistance,
In the copolymer (A), since the alcoholic hydroxyl group is introduced into the main chain terminal and / or the side chain of the copolymer chain together with the hydrolyzable silyl group, it does not have an alcoholic hydroxyl group. In comparison with the case where a vinyl copolymer having only a hydrolyzable silyl group or a blend system of the vinyl copolymer and an acrylic polyol is used, the obtained curable composition has excellent acid resistance and weather resistance. It is thought that they will exhibit sex.

In the above general formula (I), R ¹ has 1 to 10 carbon atoms, preferably, for example, methyl group, ethyl group,
n-propyl group, i-propyl group, n-butyl group, i-
It is an alkyl group having 1 to 4 carbon atoms such as a butyl group. When the alkyl group has more than 10 carbon atoms, the reactivity of the alkoxysilyl group is lowered. In addition, R
^{When 1} is a group other than an alkyl group such as a phenyl group or a benzyl group, the reactivity is lowered.

In the general formula (I), R
² is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, similar to those exemplified in the above R ¹ ,
For example, it is a monovalent hydrocarbon group selected from an aryl group having preferably 6 to 25 carbon atoms such as phenyl group and an aralkyl group having preferably 7 to 12 carbon atoms such as benzyl group. From the viewpoint that the curability of the curable composition is excellent, it is preferably an alkyl group.

In the above general formula (I), R ³ has 1 to 6 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, and a carbon number of 1. -10, preferably an alkoxyl group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group.

Specific examples of the hydrolyzable silyl group bonded to the carbon atom represented by the general formula (I) include groups contained in a monomer containing a hydrolyzable silyl group described later.

As the copolymer (A) used in the present invention,
From the viewpoint of ease of synthesis and the like, those obtained by polymerizing a monomer containing a monomer having a hydrolyzable silyl group represented by formula (I) in the molecule are preferable.

The hydrolyzable silyl group equivalent in the copolymer (A) (resin solid content (g) of the copolymer (A) containing 1 mol of the hydrolyzable silyl group) is 380 to 30,000 g.
/ Mol is preferable from the viewpoint that a curable composition exhibiting excellent heat curability, acid resistance, weather resistance and the like can be obtained, and more preferably 410 to 3000 g / mol, and 450 to 1500 g. More preferably, it is / mol.

The alcoholic hydroxyl group equivalent (resin solid content (g) of the copolymer (A) containing 1 mol of alcoholic hydroxyl group) in the copolymer (A) is 400 to 2000 g.
/ Mol, preferably 500 to 2000 g / mol, more preferably 600 to 2000 g / mol, and further preferably 800 to 2000 g / mol. When the alcoholic hydroxyl group equivalent is less than 400 g / mol, the acid resistance of the coating film formed by using the obtained curable composition is lowered, and when it exceeds 2000 g / mol. Will reduce the thermal oxidation resistance of the composition and the scratch resistance and impact resistance of the coating film.

Further, the value of the molar ratio of the alcoholic hydroxyl group to the hydrolyzable silyl group (alcoholic hydroxyl group / hydrolyzable silyl group) in the copolymer (A) is excellent in heat curability, acid resistance, and From the viewpoint of being able to obtain a curable composition exhibiting weather resistance, water resistance, etc., 0.1-3.
0, further 0.5 to 2.5, especially 0.7 to 2.0
It is preferred that

The glass transition temperature (calculated value, hereinafter also referred to as Tg) of the copolymer (A) is 0 to 70 ° C., further 10 to 6
It is preferably 0 ° C, particularly 15 to 50 ° C from the viewpoint of curability, acid resistance and weather resistance. When the temperature is lower than 0 ° C, the obtained coating film has insufficient acid resistance, and when the temperature exceeds 70 ° C, the obtained coating film tends to be brittle.

The calculation of Tg is

[0029]

[Equation 1]

W ₁ , W ₂ ; Weight fraction of monomer in acrylic resin Tg ₁ , Tg ₂ ; Homopolymer of monomer Tg (° C.) As the number average molecular weight of the copolymer (A), The curable composition of the present invention produced by using the copolymer (A) has excellent curability, and the coating film obtained from the composition has excellent coating film physical properties such as durability. ~ 300
00, further 2000-25,000, especially 300
It is preferably 0 to 12000.

As a unit constituting the copolymer (A), a unit having a hydrolyzable silyl group (hereinafter, referred to as
Examples thereof include a silyl group unit), a unit having an alcoholic hydroxyl group (hereinafter referred to as a hydroxyl unit), and a unit (hereinafter referred to as a base unit) from a monomer copolymerizable with a monomer to be these units. .

The silyl group unit is formed, for example, by polymerizing an alkoxysilyl group-containing vinyl-based copolymerizable monomer (hereinafter referred to as monomer (A-1)), and the monomer (A-1) is polymerized. Is not particularly limited as long as it contains a sex double bond and an alkoxysilyl group bonded to the carbon atom represented by the general formula (I), and specific examples thereof include

[0033]

Embedded image

General formula (II) such as:

[0035]

[Chemical 6]

(Wherein R ¹ , R ² and a are the same as above,
⁴ is a hydrogen atom or a methyl group);

[0037]

[Chemical 7]

General formula (III) such as:

[0039]

Embedded image

A compound represented by the formula: wherein R ¹ , R ² , R ⁴ and a are the same as defined above, and n is an integer of 1 to 12;

[0041]

[Chemical 9]

General formula (IV) such as:

[0043]

[Chemical 10]

A compound represented by the formula (wherein R ¹ , R ² , R ⁴ , a and n are the same as defined above);

[0045]

[Chemical 11]

General formula (V) such as:

[0047]

[Chemical 12]

A compound represented by the formula: wherein R ¹ , R ² , R ⁴ and a are the same as defined above, and m is an integer of 1 to 14;

[0049]

[Chemical 13]

(Wherein p represents an integer of 0 to 20) such as general formula (VI):

[0051]

Embedded image

(Wherein R ¹ , R ² , R ⁴ and a are the same as above, q is an integer of 0 to 22),

[0053]

[Chemical 15]

Examples thereof include compounds represented by and a (meth) acrylate having an alkoxysilyl group bonded to a carbon atom at the terminal via a urethane bond or a siloxane bond. These may be used alone or in combination of two or more. Among these, the compound represented by the general formula (III) is preferable from the viewpoint of excellent copolymerizability and polymerization stability, and curability and storage stability of the obtained curable composition.

The amount of the monomer (A-1) used is preferably 5 to 50% (% by weight, the same applies hereinafter) of the total amount of the copolymerization components, especially 5 to 35%. When the amount of the monomer (A-1) used is less than 5%, the acid resistance of the coating film formed using the curable composition obtained tends to be insufficient, and 50% If it exceeds, the storage stability of the curable composition tends to decrease.

The hydroxyl unit is, for example, an alcoholic hydroxyl group-containing vinyl monomer (hereinafter referred to as monomer (A-
2)), and specific examples of the monomer (A-2) include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter, acrylate and methacrylate are referred to as (meth) acrylate). ), 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth ) Acrylamide, Aronix 5700 manufactured by Toagosei Kagaku Kogyo Co., Ltd., 4-hydroxystyrene, HE-10 manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.
HE-20, HP-1 and HP-20 (all of which are acrylic acid ester oligomers having a hydroxyl group at the terminal), NOF CORPORATION's BLEMMER PP series (polypropylene glycol methacrylate), BLEMMER PE series (polyethylene glycol mono). Methacrylate, Bremmer PEP series (polyethylene glycol polypropylene glycol methacrylate), Bremmer AP-400 (polypropylene glycol monoacrylate), Bremmer AE-350 (polyethylene glycol monoacrylate), Bremmer NKH-5
050 (polypropylene glycol polytrimethylene monoacrylate) and Blemmer GLM (glycerol monomethacrylate), ε-caprolactone-modified hydroxyalkyl vinyl-based copolymerizable compound obtained by the reaction of hydroxyl group-containing vinyl compound and ε-caprolactone, and the like. . Of these, 2-hydroxypropyl (meth) acrylate is preferable because it can impart excellent acid resistance and water resistance to the coating film.

Typical examples of the ε-caprolactone-modified hydroxyalkylvinyl copolymerizable compound include, for example, the compound represented by the general formula (VII):

[0058]

Embedded image

(Wherein R ⁴ is the same as above, r is 1 to 10)
Placcel FA-1 (R ⁴ = H, manufactured by Daicel Chemical Industries, Ltd.) having a structure represented by
r = 1), Placcel FA-4 (R ⁴ = H, r =
4), Placcel FM-1 (R ⁴ = CH ₃ , r =
1), Placcel FM-4 (R ⁴ = CH ₃ , r =
4), UCC TONE M-100 (R ⁴ = H,
r = 2) and ^{TONEM-201 (R 4 = CH} 3, r
= 1) and so on. These monomers (A-2)
May be used alone or in combination of two or more.

The amount of the monomer (A-2) used is preferably 5 to 50%, especially 7 to 35% of the total amount of the copolymerization components. When the amount of the monomer (A-2) used is less than 5%, the resulting composition tends not to exhibit sufficient curability, and when it exceeds 50%, the curable composition is The water resistance and acid resistance of the coating film formed using the object tend to be reduced.

The base unit is formed by polymerizing a monomer copolymerizable with a monomer giving a silyl group unit and a hydroxyl group unit (hereinafter referred to as a monomer (A-3)). 3)
An example is a unit derived from a derivative of (meth) acrylic acid. The (meth) acrylic acid derivative is used for improving various properties such as flexibility or hardness of the curable composition of the present invention, gloss, light resistance, weather resistance, transparency, and water resistance. Specific examples include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-
Butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Isoboronyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (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-methyl acrylamide, AS-6, AN-6 which are macromonomers manufactured by Toagosei Kagaku Kogyo Co., Ltd.
Condensation of hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids such as AA-6, AB-6, AK-5, hydroxyalkyl esters of (meth) acrylic acid with phosphoric acid or phosphoric acid esters Examples include phosphoric acid ester group-containing vinyl compounds, which are products, and (meth) acrylates containing a urethane bond or a siloxane bond.

Monomers (A-3) other than the (meth) acrylic acid derivative are also used for further adjusting the above-mentioned various properties of the curable composition of the present invention, and specific examples thereof include
For example, 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. (Alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.), or unsaturated carboxylic acids such as diesters or half-esters of them with linear or branched alcohols having 1 to 20 carbon atoms. Acid esters; vinyl esters such as vinyl acetate, vinyl propionate, diallyl phthalate and allyl compounds; amino group-containing vinyl compounds such as vinyl pyridine and aminoethyl vinyl ether; itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide , N- Amide group-containing vinyl compounds such as nylpyrrolidone; 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.

Among the above-mentioned copolymerizable (meth) acrylic acid derivatives and copolymerizable compounds other than (meth) acrylic acid derivatives, polar copolymerization having amine, carboxylic acid, sulfonic acid or phosphoric acid group. When a polymerizable compound is used, it is desirable that the amount thereof is 0 to 5% in the component (A) in order to suppress the crosslinking reaction at the time of polymerization.

The component (A) may contain a segment formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50%, and a monomer (other than a (meth) acrylic acid derivative ( It may contain a segment derived from A-3).

The amount of the monomer (A-3) used is preferably 20 to 90% of the copolymerization component, and more preferably 50 to 80%. When the amount of the monomer (A-3) used is less than 20%, the flexibility tends to be impaired, and when it exceeds 90%, it is one of the effects of the present invention. The curability tends to be impaired.

The component (A) may contain a polyester chain, a polyether chain, a polyamide chain, a urethane chain, etc. in addition to the vinyl copolymer chain.

The copolymer (A) is composed of the monomer (A
-1), the monomer (A-2), the monomer (A-3) and the like, for example, JP-A-54-36395.
JP-A-57-36109, JP-A-58-36109
Although it can be produced by the method described in JP-A-157810, it is preferably produced by a solution polymerization method using an azo radical polymerization initiator such as azobisisobutyronitrile from the viewpoint of ease of synthesis. .

The polymerization solvent used in the solution polymerization method is
It is not particularly limited as long as it is non-reactive, but is not particularly limited, for example, hydrocarbons such as toluene, xylene, n-hexane and cyclohexane; acetic acid esters such as ethyl acetate and butyl acetate; ethyl cellosolve, butyl cellosolve, cellosolve acetate. Ethers such as; methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, ketones such as acetone, and the like.

In the solution polymerization, if necessary, for example, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, (CH ₃ O) ₃ Si—S—S—Si (O
_{CH 3) 3, (CH 3} O) 3 Si-S 8 -Si (OCH
₃ ) The molecular weight of the obtained copolymer (A) may be adjusted by using a chain transfer agent such as ₃ alone or in combination of two or more kinds. In particular, when a chain transfer agent having an alkoxysilyl group bonded to a carbon atom such as γ-mercaptopropyltrimethoxysilane is used in the molecule, the carbon atom is bonded to the carbon atom at the end of the copolymer (A). It is preferable because an alkoxysilyl group can be introduced.

The chain transfer agent is used in an amount of 0.05 to 10%, especially 0.1 to 8%, based on the total amount of the monomers used.
%.

Specific examples of the copolymer (A) thus obtained include, for example, γ-methacryloxypropyltrimethoxysilane (10-40%), 2-hydroxypropyl acrylate (5-50%), styrene (0-). Thirty
%), Methyl methacrylate (5 to 50%), n-butyl acrylate (5 to 50%) copolymer, γ-
Methacryloxypropyltrimethoxysilane (20-3
0%), 2-hydroxyethyl methacrylate (5-1
5%), styrene (10-20%), methyl methacrylate (20-50%), n-butyl acrylate (10
Up to 30%). These may be used alone or in combination of two or more.

The curable composition of the present invention contains an amino resin (B) in addition to the copolymer (A), which is more than that of the copolymer (A) alone. The obtained coating film has about the same acid resistance at high temperature and excellent appearance, and the curability and storage stability of the composition are excellent.

The amino resin (B) used in the present invention includes amino resins (melamine resin, urea resin, melamine resin, urea resin, melamine resin, urea, benzoguanamine, glycolurea, acetoguanamine, dicyandiamide, etc. A methylolated amino resin such as guanamine resin). Aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like.

Among the above, melamine resin is preferably used from the viewpoints of improving the finished appearance and curability.

Further, the above amino resin (for example, methylolated amino resin) is replaced with methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2
It is also possible to use those which are further etherified with an alcohol such as -ethylbutanol or 2-ethylhexanol.

As the amino resin (B), specifically, Uban 20SE and 20SE-6 manufactured by Mitsui Toatsu Chemicals, Inc.
0, U-ban 128, U-Van 220, U-Van 22
5, n-butylated melamine resin such as Uban 20SB, Uban 20SE60, Uban 21R, Uban 22R, Uban 122, Uban 28-60, Uban 20HS, Uban 2028, Uban 202, Uban 120, Uban 62, Uban 69-1, Isobutylated melamines such as Uban 169 and Uban 2061, butylated urea resins such as Uban 10S-60 and Uban 10R, Cymel 303, Cymel 232, Cymel 370, and Cymel 3 manufactured by Mitsui Cyanamid Co., Ltd.
25, Cymel 236, Cymel 738, Cymel 77
1, Cymel 327, Cymel 703, Cymel 70
1, Cymel 266, Cymel 267, Cymel 28
5, Cymel 235, Cymel 238, Cymel 114
1, Cymel 272, Cymel 254, Cymel 20
2, Cymel 1156, Cymel 1158, Cymel 3
00, Cymel 301, Cymel 350, Cymel 73
Melamine resins such as 6 are mentioned, and Cymel 23
Alkyl etherified melamine resins such as 5, Cymel 238 and Cymel 1158 are preferable from the viewpoint of curability.

Examples of the component (C) curing catalyst used in the present invention include organic tin compounds, acidic phosphoric acid esters,
Reaction product of acidic phosphoric acid ester and amine, saturated or unsaturated polyvalent carboxylic acid or acid anhydride thereof, sulfonic acid or reaction product of sulfonic acid and amine, organic titanate compound, organic aluminum compound or mixture thereof, etc. Can be given.

Among the above curing catalysts, the reaction product of sulfonic acid and amine, that is, the reaction product of sulfonic acid and amine, that is, the storage stability of one liquid at room temperature and the curability during baking at 100 ° C. or higher (usually 120 ° C. or higher). A compound in which the sulfonic acid group of the sulfonic acid compound is blocked with an amine is preferable.

Examples of the sulfonic acid compound include dodecylbenzenesulfonic acid, 1-octanesulfonic acid, p-toluenesulfonic acid, 2-acrylamido-2.
-Methyl propane sulfonic acid and the like.

Examples of the amine used for blocking the sulfonic acid group include aliphatic chain amines, aliphatic cyclic amines, aromatic amines and the like. 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 can be mentioned.

Specific examples of the catalyst in which sulfonic acid is blocked with these amines include Nacure 5225 (King Industries
Manufactured).

The ratio of the amine used to the sulfonic acid is such that the amine is 0.5 to 1 equivalent to 1 equivalent of the sulfonic acid group.
It is preferably 3.0 equivalents. When the equivalent of amine to 1 equivalent of sulfonic acid group is less than 0.5, the storage stability of 1-liquid and the appearance of the coating film are deteriorated, and when it exceeds 3.0, the coloration of the coating film and the appearance are deteriorated. Water resistance tends to decrease.

With respect to 1 equivalent of the sulfonic acid group, the amine content was 0.
75 equivalents or more, more preferably 0.9 equivalents or more, and especially 1.
It is more preferably 0 equivalent or more from the viewpoint of storage stability of one liquid and improvement of appearance of the coating film, and amine is 2.5 equivalents or less, further 2.0 equivalents or less to prevent coloration of the coating film, It is preferable from the viewpoint of improving water resistance.

Specific examples of the curing catalyst other than the reaction product of the sulfonic acid and the amine include organic tin compounds (dibutyltin laurate, dibutyltin dimaleate, dioctyltin laurate, etc.), acid phosphates (monomethyl phosphate, monomethyl phosphate). Ethyl phosphate, monobutyl phosphate, monooctyl phosphate, monododecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, didodecyl phosphate, etc., acidic phosphate ester (specific examples are the same as the specific examples of the acidic phosphate ester) Can be given)
And these amines and (hexylamine, di-2-ethylhexylamine, N, N-dimethyldodecylamine, dodecylamine, DABCO (1,4-diazabicyclo [3,2,2] octane), DBU, morpholine, diisopropanol Reaction products with amines, saturated or unsaturated polycarboxylic acids or their acid anhydrides (maleic acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, succinic acid, phthalic acid, trimellitic acid) , Pyromellitic acid or their acid anhydrides), organozirconium compounds (tetrabutylzirconate, tetrakis (acetylacetonato) zirconium, butoxytris (acetylacetonato) zirconium, etc.), organoaluminum compounds (amylniumtris (acetyl)). Acetonate) Aluminum tris (ethylacetoacetate), aluminum monoacetylacetonate bis (ethylacetoacetate), etc.) and the like.

The mixing ratio of the copolymer (A) and the amino resin (B) is preferably 0.01 to 5 parts of the component (B) per 100 parts of the component (A). If the amount of the component (B) is less than 0.01 part, the curability and storage stability of the curable composition will be significantly impaired, and if it is more than 5 parts, the acid resistance of the coating film will be significantly reduced. The component (B) is preferably 0.1 part or more, more preferably 0.5 part or more from the viewpoint of storage stability, curability and finished appearance, and is 4.9 parts or less, further 4.5 parts or less. It is preferable from the viewpoint of acid resistance.

The amount of the curing catalyst as the component (C) used is 0.001 to 10 parts, preferably 0.05 to 10 parts, per 100 parts of the total of the components (A) and (B). . When the amount of component (C) used is less than 0.001 part, the curability of the curable composition tends to decrease, and when it exceeds 10 parts, the appearance of the coating film tends to decrease.

When it is desired to reduce the viscosity of the curable composition of the present invention, tetraalkoxysilane, alkyltrialkoxysilane, partial hydrolysates thereof and the like are added to 100 parts of the copolymer (A). On the other hand, the amount may be preferably 50 parts or less, more preferably 30 parts or less.

Further, the curable composition of the present invention contains an acrylic polyol in order to improve the thermosetting property of the composition and the impact resistance of the coating film formed by using the composition.
For a hydroxyl group-containing polymer compound such as polycarbonate diol or polyester diol, the molar ratio of the alcoholic hydroxyl group to the hydrolyzable silyl group (alcoholic hydroxyl group / hydrolyzable silyl group) is within the range of 0.1 to 3. It may be blended as described in 1.

By adding a dehydrating agent or a solvent to the curable composition of the present invention, the storage stability of the curable composition can be further improved.

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. These may be used alone or in admixture of two or more.

The dehydrating agent may be added at the time of polymerization of the copolymer (A) or may be added after the polymerization. If the amount of the dehydrating agent is too large, the curing amount obtained is too high. In a coating film formed using the resin composition, defects such as cracking (foaming phenomenon) tend to occur, and therefore 70 parts or less, preferably 50 parts or less, relative to 100 parts of the copolymer (A). , And more preferably 20 parts or less.

Examples of the solvent include alkyl alcohols having an alkyl group having 1 to 10 carbon atoms, and specific examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n. -Butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-
Examples thereof include butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol and octyl alcohol.

The above-mentioned solvents such as alkyl alcohol may be used alone or in combination of two or more kinds, and the compounding amount thereof is not particularly limited, but when it is too much, the curable composition obtained is obtained. In the coating film formed by using (1), defects such as armpits (foaming phenomenon) tend to occur, and therefore, usually 0.5 to 70 parts, preferably 1 to 100 parts of the copolymer (A). The amount is preferably 50 parts, more preferably 2 to 20 parts.

When the dehydrating agent and the solvent are used in combination, the storage stability is further improved as compared with the curable composition obtained by blending the copolymer (A) and the amino resin (B). The amounts of the dehydrating agent and the solvent that produce such effects are such that the copolymer (A) in the curable composition of the present invention is
And the molecular weight and composition of the amino resin (B) may be taken into consideration so that the curable composition may be adjusted so as to have a resin solid content concentration, viscosity, etc. which are practically necessary.

By mixing the curable composition of the present invention with, for example, an ultraviolet absorber and a light stabilizer, its weather resistance can be further improved, and particularly by using these in combination, the weather resistance is further improved. Can be made.

Examples of the ultraviolet absorber include benzophenone-based, triazole-based, phenylsalicylate-based, diphenylacrylate-based, acetophenone-based UV absorbers, which may be used alone or in combination of two or more. You can

Examples of the light stabilizer include bis (2,2,6-tetramethyl-4-piperidyl) sebacate and bis (1,2,2,6,6-pentamethyl-4-).
Piperidyl) sebacate, 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), tetrakis (2,2,6,6-Tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1 , 2,3,4-butanetetracarboxylate and the like, and these can be used alone or in admixture of two or more.

The amount of the ultraviolet absorber compounded is usually 0.1 to 10 parts with respect to 100 parts of the resin solid content of the curable composition,
It is preferably 1 to 5 parts, and the amount of the light stabilizer is usually 0.1 to 10 parts, and particularly 1 to 5 parts per 100 parts of the resin solid content of the curable composition. Is preferred.

Further, when the curable composition of the present invention is used as a clear paint, additives such as diluents, cissing inhibitors and leveling agents; fibrin compounds such as nitrocellulose and cellulose acetate butyrate; epoxy A resin, a vinyl chloride resin, a chlorinated polypropylene, a chlorinated rubber, a resin such as polyvinyl butyral, or the like can be appropriately blended depending on the application.

The curable composition of the present invention has low toxicity,
It is also possible to adjust to a high solid having a solid content concentration of 50 to 70%. The curable composition of the present invention is applied to a substrate by a method such as spray coating, brush coating, roll coating or dip coating, and then cured by heating at about 80 to 160 ° C. to obtain acid resistance. It is possible to obtain a cured coating film having excellent chemical resistance, water resistance, weather resistance, scratch resistance, and appearance.

As described above, the curable composition of the present invention exhibits excellent water resistance, abrasion resistance, appearance, thermosetting property and the like, and exhibits extremely excellent acid resistance. It can be suitably used as a top coat paint for industrial machinery, steel furniture, interior and exterior of buildings, home appliances, plastics, etc., especially for automobiles.

Next, the curable composition for top coating composition of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Production Examples 1 to 5 (Production of Copolymer (A) and Copolymer for Comparative Example) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel. 26 parts of Solvesso 100 (Petroleum aromatic solvent manufactured by Exxon Chemical Co., Ltd.) was charged, and the temperature was raised to 110 ° C. while introducing nitrogen gas.
The copolymerization component having the composition shown in Table 1, 2,2′-azobis (2
-Methylbutyronitrile) (trade name: V-59, manufactured by Wako Pure Chemical Industries, Ltd.) 5.7 parts, Solvesso 100 3.5.
Part and 2 parts of methanol were added dropwise at a constant rate from a dropping funnel over 4 hours.

After completion of dropping the mixture, 0.3 part of V-59 and 10 parts of xylene were dropped at a constant rate over 30 minutes, and 1 part was added.
Polymerization was carried out for 30 minutes, then cooled, 4 parts of methyl orthoacetate and 4 parts of methanol were added, and Solvesso 100 was added to the resin solution to adjust the resin solid content concentration to 60%. To obtain a solution of.

The number average molecular weight of the obtained copolymer, the hydrolyzable silyl group equivalent (g / mol), the alcoholic hydroxyl group equivalent (g / mol), and the molar ratio of the alcoholic hydroxyl group and the hydrolyzable silyl group ( Table 1 shows the values of alcoholic hydroxyl group / hydrolyzable silyl group), Tg and conversion rate. The abbreviations of the copolymers are also shown in Table 1.

The abbreviations of the copolymerization components in Table 1 are as shown below.

MPTMSi: γ-methacryloxypropyltrimethoxysilane HPA: 2-hydroxypropyl acrylate HEMA: 2-hydroxyethyl methacrylate ST: styrene MMA: methyl methacrylate NBA: n-butyl acrylate

[0109]

[Table 1]

Examples 1 to 8 and Comparative Examples 1 to 5 Cymel 235 of the copolymers obtained in Production Examples 1 to 5 and a commercially available melamine resin (all methylol groups are alkyl etherified (methyl / butyl = 6/4) )) And Cymel 238 (type in which all methylol groups are alkyl etherified (methyl / isobutyl = 6/4)) were blended so as to have the composition shown in Table 2. In each of the Examples and Comparative Examples, 0.4 parts of a leveling agent (# 1984-50, manufactured by Kusumoto Kasei Co., Ltd.) and Tinuvin 384 as an ultraviolet absorber, based on the total solids of the copolymer and melamine resin, respectively. 2 parts (manufactured by Ciba Geigy), 1 part tinuvin 123 (manufactured by Ciba Geigy) as a light stabilizer, (C)
Dodecylbenzenesulfonic acid / diisopropanolamine = 1 / 1.03 (equivalent ratio) as a curing catalyst for the components (however, in Example 7, dodecylbenzenesulfonic acid / 2-
Methyl-2-amino-1-propanol = 1 / 1.03
(Equivalent ratio) Further, in Example 8, a mixture of dodecylbenzenesulfonic acid / morpholine = 1 / 0.8 (equivalent ratio).
0 parts was added. This mixture was diluted with Solvesso 100 to adjust the viscosity of the Ford cup to 15 to 20 seconds to obtain a clear coating for top coat.

[0111] A degreased and phosphorylated mild steel plate coated with an automotive epoxyamide-based cationic electrodeposition primer and an intermediate coat surfacer was used as a test piece, and a high solid type acrylic melamine resin coating was applied on it. (Black metallic base) was applied 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. Table 2 shows the results.

(Gel Fraction) A free clear film (thickness: 5) obtained by applying a clear paint coated on a polyethylene sheet for 30 minutes at 120 ° C. or 140 ° C.
(0 μm) was wrapped in a 300-mesh stainless wire mesh (W ₀ ) that had been precisely weighed, and weighed (W ₁ ). This is immersed in acetone for 24 hours for extraction, then dried,
The weight was precisely weighed (W ₂ ) and the gel fraction was calculated according to the following formula.

Gel fraction (%) = 100 × (W ₂ −W ₀ ).
/ (W ₁ −W ₀ ) × 100 (acid resistance) 40% sulfuric acid aqueous solution (4 drops) was dropped on the test panel using a pipette, heated in a dryer at 85 ° C. for 30 minutes, and then the aqueous sulfuric acid solution was added with water. It was washed off and the state of change of the coating film surface was observed and evaluated according to the following criteria.

(Evaluation Criteria) 10 points: No change compared to before dropping. 9 points: A slight change is recognized. 8 points: A circular mark remains. 7 points: Discoloration and swelling are slightly observed. 6 points: A slight decrease in gloss and a slight discoloration are observed. 5 points: A decrease in gloss and discoloration are clearly observed. 4 points: Slight shrinkage and clear swelling are observed. 3 points: slight lifting, severe shrinkage, and discoloration are observed. 2 points: Lifting is clearly recognized. 1 point: Dissolution of the coating film is observed.

(Storage stability) Diluted paint (resin solid content 48
%) 10 g in a bottle with a diameter of 2.5 cm, and leave it at room temperature (23 ° C.) in an open state, and then measure the number of days until it gels (when the bottle is bent sideways and the paint does not flow). The storage stability was evaluated.

(Water resistance) The coated plate was immersed in warm water at 40 ° C for 240
After soaking for a period of time, it was taken out and the state of the coating film was observed.

◯: No abnormalities such as glossiness and blistering of the coating film Δ: Slight glossiness and blistering of the coating film are observed ×: Significant glossiness and blistering of the coating film are observed (Appearance) Image clarity measurement Vessel (ICM, manufactured by Suga Test Instruments Co., Ltd.)
The sharpness of the coating film was measured using a -1-DP type, slit width: 0.5 mm).

The larger the value of the image clarity, the better the appearance.

[0120]

[Table 2]

From the results shown in Table 2, the coating materials obtained in Examples 1 to 7 are excellent in curability and storage stability, and at the same time, excellent in acid resistance at high temperature. I understand.

[0122]

The curable composition for a top coating composition of the present invention comprises:
It has good curability, storage stability, etc. and is well balanced, and exhibits excellent acid resistance at high temperatures. Therefore, it can be suitably used for a top coat paint used for automobiles, industrial machines, steel furniture, interiors and exteriors of buildings, household appliances, plastics and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Nanbu, Azajigaoka 7-chome, Tarumi-ku, Kobe-shi, Hyogo 1722-20 (72) Hisao Furukawa 4-5-11 Chikushigaoka, Kita-ku, Kobe-shi, Hyogo

Claims (8)

[Claims] 1. A main chain of (A) consists essentially of a vinyl-based copolymer chain, and the main chain ends and / or side chains have the general formula (I): (In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ² is a monovalent carbon atom selected from the group consisting of a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group. Hydrogen group, R ³ is an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, but 2 R
³ does not have to be the same, a is 0 to 2 and b is an integer of 0 to 10) and has at least one hydrolyzable silyl group bonded to the carbon atom in the molecule, and It has at least one alcoholic hydroxyl group at the chain end and / or side chain, and has an alcoholic hydroxyl group equivalent of 400 to 20.
100 parts by weight of a vinyl-based copolymer having a concentration of 00 g / mol (B) 0.01 to 5 parts by weight of an amino resin and (C) a curing catalyst based on 100 parts by weight of the total amount of the components (A) and (B). Curable composition for topcoat paints containing 0.001 to 10 parts by weight. 2. The hydrolyzable silyl group equivalent in the copolymer (A) is 380 to 30000 g / mol.
A curable composition for a top coating composition as described above. 3. The value of the molar ratio of the alcoholic hydroxyl group and the hydrolyzable silyl group (alcoholic hydroxyl group / hydrolyzable silyl group) in the copolymer (A) is 0.1 to 3. A curable composition for topcoat paint according to 1 or 2. 4. The curable composition for a topcoat paint according to claim 1, wherein the glass transition temperature (calculated value) of the copolymer (A) is 0 to 70 ° C. 5. The copolymer (A) is a copolymer obtained by using, as a copolymerization component, 2-hydroxypropyl (meth) acrylate, which is a vinyl compound containing an alcoholic hydroxyl group. Curable composition for topcoat paint. 6. The topcoat paint according to claim 1, wherein the curing catalyst (C) is a reaction product of a sulfonic acid and an amine using 0.5 to 3.0 equivalents of amine with respect to 1 equivalent of sulfonic acid group. Curable composition. 7. The curable composition for top coat paints according to claim 6, wherein the amine is a primary or secondary amine having at least one hydroxyl group in one molecule. 8. The curable composition for a topcoat paint according to claim 6, wherein the amine is morpholine.