JPH11116894A - Curable composition for top-coat paint and coated product obtained by applying it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition for a topcoat paint which has excellent weather resistance and gives a coating film having excellent stain resistance, adhesion and the like. SOLUTION: embedded image (R ¹ is a hydroxyl group or an alkyl group having 1 to 10 carbon atoms;
² is a hydrogen atom or a monovalent hydrocarbon group selected from an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms, and a is a reactive silyl group bonded to a carbon atom represented by the following formula: And 100 parts by weight of an acrylic copolymer (A) containing a hydroxyl group, (R ³ is a monovalent hydrocarbon group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group, and R ⁴ is selected from an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group. A monovalent hydrocarbon group, b represents 0 or 1) a silicon compound represented by 0 or 1) and / or 2 to 70 parts by weight of a hydrolytic condensate thereof (B), and (C) a compound 0.1 having two or more isocyanate groups. ~ 30 parts by weight, (D)
The composition contains 0.1 to 10 parts by weight of a curing catalyst and 0.01 to 10 parts by weight of (E) a polyether-modified dimethylpolysiloxane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a curable resin composition for a top coat. More specifically, for example, metal, ceramics, glass, cement, ceramic moldings,
Plastics, woods, papers, buildings composed of fibers, etc., home appliances, industrial equipment, curable resin compositions for topcoats that can be suitably used for automotive coatings, etc., and curable resin compositions for such topcoats Related to painted objects.

[0002]

2. Description of the Related Art Conventionally, the surface of industrial products such as ceramic moldings, buildings made of concrete or steel, building materials, etc. is conventionally coated with, for example, fluororesin paint, acrylic urethane paint, acrylic silicone paint. By coating with such paints, the appearance of buildings and the like is improved, and the anticorrosion property and weather resistance are improved. At the same time, due to the recent deterioration of the environment, especially in urban areas, and an increase in awareness of the protection of aesthetics and landscapes, products having the above-mentioned paints imparted with stain resistance performance have been developed and put on the market.

[0003] Among them, acrylic silicone paints have insufficient adhesion and performance such as shrinkage generated during recoating, depending on the object to be coated, as compared with the other two, depending on the cross-linking form, and areocyanate compound. These properties have been improved by the addition of.

[0004] However, it is possible to use an acrylic melamine coating, a fluorsomeramine coating, an acrylic urethane coating, an acid-
In the case of overcoating on a thermosetting coating film such as an epoxy coating film, or after coating these base coats, in a car application where a wet-on-wet coating method (2 coats 1 bake) is used, it is extremely high. Appearance is required. For this reason, a surface conditioner (leveling agent) is indispensable. However, when a leveling agent is added, the appearance is obtained, but the contact angle is increased and the stain resistance is not exhibited.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above situation, and as a result, have found that an acrylic copolymer containing a specific reactive silyl group and a hydroxyl group as essential components has been developed. A silicone compound, a polyfunctional isocyanate compound, a specific curing catalyst, a composition in which a specific polyether-modified dimethylpolysiloxane is blended in a specific ratio has curability at room temperature or under heating, and from the composition Was found to have excellent weather resistance as well as a coating film from an acrylic silicone resin paint, and at the same time, had excellent stain resistance, adhesion, solvent resistance, and impact resistance.

That is, the curable composition for a top coating composition of the present invention has the general formula (I):

Embedded image (Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group, and an aralkyl group selected from an aralkyl group.
A is an integer of 0 to 2; Acrylic copolymer (A) 10 containing, as essential components, a reactive silyl group and a hydroxyl group bonded to a carbon atom represented by
With respect to 0 parts (parts by weight, hereinafter the same), the general formula (II):

Embedded image (Wherein, R ³ is a monovalent hydrocarbon group selected from an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms, and R ⁴ is an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms. A monovalent hydrocarbon selected from the group, b represents 0 or 1.) 2 to 70 parts by weight of a silicon compound represented by the following formula:
0.1 to 30 parts by weight of a compound having two or more isocyanate groups as a crosslinking agent (C), 0.1 to 30 parts by weight of a curing catalyst (D)
10 parts by weight, and 0.01 to 10 parts by weight of a polyether-modified dimethylpolysiloxane (E).

The acrylic copolymer (A) contains 3-90% by weight of a monomer unit having a reactive silyl group bonded to a carbon atom represented by the general formula (I) in the molecule. It is preferable that they are united (claim 2).

The curing catalyst (D) is preferably an organometallic compound, particularly preferably a tin compound containing an S atom in the molecule.
4).

The curable composition may further contain a mercapto group-containing hydrocarbon and / or mercaptosilane (F).

[0010] The coated product of the present invention is a coated product in which a top coat clear paint is applied to an application surface on which a paint containing a metallic powder and / or a color pigment is applied, wherein the top coat clear paint is: The curable composition for paints of any of the above is contained as a main component (claim 6).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The curable composition for a top coating composition of the present invention has a general formula (I) as a base resin having curability at room temperature in the presence of moisture (moisture).

Embedded image (Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aryl group, and an aralkyl group selected from an aralkyl group.
A is an integer of 0 to 2; The acrylic copolymer (A) containing as an essential component a reactive silyl group and a hydroxyl group bonded to a carbon atom represented by the formula (A) is contained.

The acrylic copolymer (A) has a main chain substantially consisting of a main chain copolymerized with an acrylic monomer (hereinafter, also referred to as a main chain substantially consisting of an acrylic copolymer chain). )) Because it is a copolymer, the weather resistance of a coating film formed from the curable resin composition for a topcoat paint of the present invention obtained;
Excellent in chemical resistance and the like.

In the above description, "the main chain of the acrylic copolymer (A) is substantially composed of an acrylic copolymer chain."
Means that at least 50% (% by weight, the same applies hereinafter), more preferably at least 70%, of the units constituting the main chain of the acrylic copolymer (A) are formed from acrylic monomer units. Means that

Further, since the acrylic copolymer (A) contains a reactive silyl group bonded to a carbon atom, the coating has excellent water resistance, alkali resistance, acid resistance and the like. Become.

In the acrylic copolymer (A), the number of reactive silyl groups bonded to carbon atoms represented by the general formula (I) is preferably at least 2 per molecule of the acrylic copolymer (A), Is preferably 3 or more from the viewpoint that a coating film formed from the composition of the present invention has excellent durability such as weather resistance and solvent resistance.

The reactive silyl group represented by the general formula (I) may be bonded to an end of the main chain of the acrylic copolymer (A) or may be bonded to a side chain. It may be attached to the chain ends and side chains.

In the general formula (I), R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably
For example, a carbon number of 1-4 such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group and an i-butyl group.
Is an alkyl group. When the alkyl group has more than 10 carbon atoms, the reactivity of the reactive silyl group decreases. Also, when R ¹ is a group other than an alkyl group such as a phenyl group and a benzyl group, the reactivity of the reactive silyl group is reduced.

In the above general formula (I), R
² is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms as exemplified for R ¹ above, for example, an aryl group preferably having 6 to 25 carbon atoms such as a phenyl group; It is preferably a monovalent hydrocarbon group selected from aralkyl groups having 7 to 12 carbon atoms such as a benzyl group. Among them, an alkyl group having 1 to 4 carbon atoms is preferable from the viewpoint that the composition of the present invention is excellent in curability.

In the general formula (I), (R ¹ O)
_3-a is selected such that 3-a is 1 or more and 3 or less, that is, a is 0 to 2, but from the viewpoint that the curability of the acrylic copolymer (A) becomes good. In the formula, a is preferably 0 or 1. Therefore, the number of bonds of R ² is preferably 0 to 1.

When the number of (R ¹ O) or R ^{2 in} the general formula (I) is 2 or more, R ¹ contained in 2 or more is included.
Or, R ² may be the same or different.

Specific examples of the reactive silyl group bonded to the carbon atom represented by the general formula (I) include, for example, a group contained in a monomer containing a reactive silyl group described below.

The acrylic copolymer (A) has the general formula (I) in its molecule because of its ease of synthesis.
Those containing a monomer unit containing a reactive silyl group bonded to a carbon atom represented by In addition, the content ratio of the monomer unit in the acrylic copolymer (A) is preferably 3 because the coating film formed using the composition of the present invention has excellent durability and high strength. ~ 90%,
Especially, it is preferable that it is 10 to 70%, especially 10 to 50%.

The monomer units other than the monomer units having a reactive silyl group bonded to a carbon atom represented by the general formula (I) contained in the acrylic copolymer (A) are described below. And units from other monomers used as necessary as described below.

The acrylic copolymer (A) has a number average molecular weight of 1,000 to 30,0 from the viewpoint that the coating film formed using the composition of the present invention has excellent physical properties such as durability.
00, especially 3,000 to 25,000.

Acrylic copolymer (A) as described above
May be used alone or in combination of two or more.

Next, an example of a method for producing the acrylic copolymer (A) will be described.

The acrylic copolymer (A) is, for example, a monomer containing a polymerizable double bond and a reactive silyl group bonded to a carbon atom (hereinafter, referred to as monomer (A-1)), and a hydroxyl group-containing monomer. Monomer (hereinafter, monomer (A-
2). ), (Meth) acrylic acid and / or a derivative thereof (hereinafter, referred to as monomer (A-3)) and other monomers used as necessary.

Specific examples of the monomer (A-1) include, for example,

Embedded image General formula (III) such as:

Embedded image (Wherein, R ¹ , R ² and a are the same as described above, and R ⁵ represents a hydrogen atom or a methyl group);

Embedded image General formula (IV) such as:

Embedded image (Wherein R ¹ , R ² , R ⁵ and a are the same as defined above, n
Represents an integer of 1 to 12. A compound represented by);

Embedded image General formula (V) such as:

Embedded image (Wherein, R ¹ , R ² , R ⁵ , a and n are the same as described above);

Embedded image General formula (VI) such as:

Embedded image (Wherein R ¹ , R ² , R ⁵ and a are the same as defined above, m
Represents an integer of 1 to 14. A compound represented by);

Embedded image (Wherein p represents an integer of 0 to 20).
II):

Embedded image (Wherein, R ¹ , R ² , R ⁵ and a are the same as above, and q is 0
Represents an integer of ~ 22. And a (meth) acrylate having a reactive silyl group bonded to a carbon atom at the terminal via a urethane bond or a siloxane bond. Among them, the compound represented by the above general formula (IV) is preferable in terms of excellent copolymerizability and polymerization stability, and excellent curability and storage stability of the obtained composition.

These monomers (A-1) may be used alone or in combination of two or more.

As described above, the monomer (A-1) is a monomer having a reactive silyl group bonded to a carbon atom represented by the general formula (I) in the obtained acrylic copolymer (A). It is preferable to use such that the body unit is contained at 3 to 90%, more preferably 10 to 70%, particularly preferably 10 to 50%.

Specific examples of the monomer (A-2) include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) Acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, 4-hydroxystyrene vinyltoluene, Alonix 5700, 4-hydroxystyrene manufactured by Toa Gosei Chemical Industry Co., Ltd., HE manufactured by Nippon Shokubai Chemical Industry Co., Ltd. -10,
HE-20, HP-1 and HP-20 (all of which are acrylate oligomers having a hydroxyl group at a terminal), Blemmer PP series (polypropylene glycol methacrylate), Blemmer PE series (polyethylene glycol mono) manufactured by NOF Corporation (Methacrylate), Blemmer PEP series (polyethylene glycol polypropylene glycol methacrylate), Blemmer AP-400 (polypropylene glycol monoacrylate), Blemmer AE-350 (polyethylene glycol monoacrylate), and Blemmer G
LM (hydroxyalkyl esters of (meth) acrylic acid such as glycerol monomethacrylate, N-methylol (meth) acrylamide, hydroxyl-containing compounds and ε-
Ε-caprolactone-modified hydroxyalkyl vinyl copolymerizable compound P obtained by reaction with caprolactone
lacel FA-1, PlacelFA-4, P
lacel FM-1, Placcel FM-4
(These are Daicel Chemical Industries, Ltd.), TONE M-
201 (manufactured by UCC) and a polycarbonate-containing vinyl compound (specific examples include HEAC-1 (manufactured by Daicel Chemical Industries, Ltd.)), among which 2-hydroxyethyl (meth) acrylate, 2-hydroxy Propyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate have excellent reactivity with isocyanate, and provide a coating film having good weather resistance, chemical resistance, and impact resistance. Particularly preferred are 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and the amount used is the hydroxyl equivalent (the molecular weight of the resin per OH group). ) Is preferably 300 or more, more preferably 400 or more, and particularly preferably 5 or more.
00 or more is preferable.

These alcoholic hydroxyl group-containing vinyl copolymerizable compounds may be used alone or in combination of two or more.

Specific examples of the monomer (A-3) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate,
tert-butyl (meth) acrylate, 3,3,5-
Trimethylcyclohexyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth)
Acrylate, lauryl (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, isobornyl (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 (meth) acrylamide, (meth) acryloylmorpholine, Alonix M-5700, macromonomers AS-6, AN-6, AA-6, AB-6, AK-
6 and the like (these are manufactured by Toa Gosei Chemical Industry Co., Ltd.),
Phosphoric acid ester group-containing (meth) acrylic compounds such as condensation products of hydroxyalkyl esters of (meth) acrylic acid and phosphoric acid or phosphoric acid esters, (meth) acrylates containing urethane bonds or siloxane bonds, etc. No. Among them, n- is preferred because the obtained acrylic copolymer (A) has excellent compatibility with the silicon compound represented by the following general formula (II) and / or its hydrolysis condensate (B). It preferably contains butyl methacrylate.

These monomers (A-2) may be used alone or in combination of two or more.

The total amount of the monomers (A-2) and (A-3) used may be appropriately adjusted in accordance with the type and amount of the monomer (A-1) to be used. 5 to 90%, especially 30 to 85%, especially 5
Preferably it is 0-85%. The monomer (A-
The use amount of 1) is preferably 1 to 50%, more preferably 3 to 40%, particularly preferably 5 to 30% of the polymerization component. When n-butyl methacrylate is used as the monomer (A-3), the amount used is 20 to 5 times the amount of the monomer used.
0% means compatibility with the silicon compound represented by the following general formula (II) and / or its hydrolysis condensate (B), and various types of coating films formed from the obtained curable composition. It is preferable because the balance of characteristics is excellent.

In the present invention, for the purpose of further improving the weather resistance of a coating film formed from the obtained composition of the present invention, for example, a segment or monomer (U) formed on the main chain by a urethane bond or a siloxane bond. A-1), a monomer (A-2), and a segment derived from a monomer other than the monomer (A-3) are introduced into the acrylic copolymer (A) within a range not exceeding 50%. Is also good.

The monomer (A-1) and the monomer (A-
2) Specific examples of the monomer other than the monomer (A-3) include, for example, styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene,
Aromatic hydrocarbon vinyl compounds such as vinyl toluene;
Unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid and the like, salts thereof such as alkali metal salts, ammonium salts and amine salts; acid anhydrides of unsaturated carboxylic acids such as maleic anhydride and these acid anhydrides Esters of unsaturated carboxylic acids such as diesters or half esters with linear or branched alcohols having 1 to 20 carbon atoms; vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; vinyl pyridine; Amino group-containing vinyl compounds such as aminoethyl vinyl ether;
Amide group-containing vinyl compounds such as itaconic acid diamide, crotonic acid amide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone; 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene , Butadiene, isoprene, fluoroolefin maleimide, N-vinylimidazole, and other vinyl compounds such as vinylsulfonic acid.

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

The acrylic copolymer (A) may contain a group such as a carboxyl group or an amino group. In this case, the curability and the adhesion are improved, but the acrylic copolymer (A) binds to the polymer chain. In the case of a carboxyl group or an amino group, the activity is weak, and a cured product having good characteristics cannot be obtained even if they are used in place of a curing catalyst for curing.

The acrylic copolymer (A) is described in, for example, JP-A-54-36395 and JP-A-57-5595.
It can be produced by a hydrosilylation method described in JP-A No. 4 (1994) -204 or a solution polymerization method using a monomer containing a reactive silyl group, but contains a reactive silyl group from the viewpoint of ease of synthesis and the like. It is particularly preferable that the monomer is produced by a solution polymerization method using an azo-based radical polymerization initiator such as azobisisobutyronitrile.

The solvent used in this solution polymerization method is not particularly limited as long as it is non-reactive, and examples thereof include hydrocarbons such as toluene, xylene, n-hexane and cyclohexane; ethyl acetate and butyl acetate. Acetic acid esters such as ethyl cellosolve and butyl cellosolve; ether esters such as cellosolve acetate;
Examples thereof include ketones such as methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, and acetone.

In the above 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 (OC
H ₃ ) ₃ , (CH ₃ O) ₃ Si—S ₈ —Si (OC
The molecular weight of the obtained acrylic copolymer (A) may be adjusted by using a chain transfer agent such as H ₃ ) ₃ alone or in combination of two or more kinds. In particular, when a chain transfer agent having an alkoxysilyl group in the molecule such as γ-mercaptopropyltrimethoxysilane is used, it is possible to introduce a reactive silyl group at the terminal of the acrylic copolymer (A). It is preferable because it is possible. The amount of the chain transfer agent to be used is from 0.05 to 10% of the total amount of the polymerization components used, and more preferably from 0.1 to 10%.
It is preferably about 8%.

A dehydrating agent can be added to the acrylic copolymer (A) of the present invention in order to improve storage stability.

Specific examples of the dehydrating agent include methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, trimethyl orthopropionate, triethyl orthopropionate, trimethyl orthoisopropionate, triethyl orthoisopropionate, Trimethyl orthobutyrate, triethyl orthobutyrate, trimethyl orthoisobutyrate, triethyl orthoisobutyrate and the like.

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

These dehydrating agents are used in a proportion of 200 parts or less, preferably 100 parts or less, more preferably 50 parts or less, per 100 parts of the component (A).

These dehydrating agents may be added, for example, to the components before the polymerization of the acrylic copolymer (A), may be added during the polymerization of the acrylic copolymer (A), or It may be added at the time of mixing the obtained acrylic copolymer (A) and other components, and there is no particular limitation.

In the present invention, together with the above-mentioned acrylic copolymer (A), the coating film formed from the composition of the present invention is improved in the stain resistance, and the adhesion between the coating film and the object to be coated is improved. General formula (II) which is a component for improving the property:

Embedded image (Wherein, R ³ is a monovalent hydrocarbon group selected from an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms, and R ⁴ is an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms. A monovalent hydrocarbon group selected from
Represents 0 or 1. )) And / or a partial hydrolyzed condensate thereof (B) (hereinafter also referred to as a silicon compound or the like (B)). A composition obtained by mixing a silicone compound (B) with an acrylic copolymer (A) becomes a composition having room-temperature curability and heat curability, and a coating film formed using this composition has excellent resistance to heat. Although it has stain resistance, the reason why the coating film has excellent stain resistance has not been clarified yet. Probably due to the difference in the relative curing rate between the acrylic copolymer (A) and the silicone compound (B) and the compatibility, and the improvement in surface hardness and hydrophilicity.

In the general formula (II), R ³ has 1 to 10 carbon atoms, preferably, for example, a methyl group, an ethyl group,
n-propyl group, i-propyl group, n-butyl group, i-
An alkyl group having 1 to 4 carbon atoms such as a butyl group, an aryl group,
It is preferably a monovalent hydrocarbon group selected from an aryl group having 6 to 9 carbon atoms such as a phenyl group and an aralkyl group, preferably an aralkyl group having 7 to 9 carbon atoms such as a benzyl group. When the alkyl group has more than 10 carbon atoms, the reactivity of the silicon compound or the like (B) decreases. Also, when R ³ is a group other than the alkyl group, the aryl group, and the aralkyl group, the reactivity decreases.

In the general formula (II), R ⁴
Carbon atoms 1 to 10, preferably similar to several atoms and ^{R 3}
4 alkyl group, an aryl group, preferably an aryl group R ³ the same carbon number 6-9, and aralkyl groups, preferably a monovalent selected from aralkyl group R ³ the same carbon number 7-9 It is a hydrocarbon group.

In the general formula (II), (R ³ O)
_4-b is selected such that b is 0 to 1, but from the viewpoint that the curability of a coating film formed from the composition of the present invention is improved, b is preferably 0.

When the number of (R ³ O) present in the general formula (II) is two or more, R ³ contained in two or more may be the same or different.

Specific examples of the above silicon compound include, for example, tetramethyl silicate, tetraethyl silicate, tetra n-propyl silicate, tetra i-propyl silicate, tetra n-butyl silicate, tetra i
Tetraalkyl silicates such as -butyl silicate; methyltrimethoxysilane, methyltriethoxysilane,
Phenyltrimethoxysilane, phenyltriethoxysilane, octadecyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, methyltrisec-
Octyloxysilane, methyltriphenoxysilane,
Examples include trialkoxysilane such as methyltriisopropoxysilane and methyltributoxysilane.

Specific examples of the partially hydrolyzed condensate of the silicon compound include those obtained by adding water to the above-mentioned tetraalkoxysilane or trialkoxysilane in a usual manner and condensing it. M
SI51, ESI28, ESI40, HAS-1, HA
S-10 (manufactured by Colcoat Co., Ltd.), MS56 (manufactured by Mitsubishi Chemical Co., Ltd.) and other partially hydrolyzed condensates of tetraalkoxysilanes, such as AFP-1 (manufactured by Shin-Etsu Chemical Co., Ltd.) Examples include partial hydrolysis condensates of trialkoxysilane.

These silicon compounds (B) may be used alone or in combination of two or more.

Among the above silicon compounds and the like (B),
MSI51 (tetramethoxy) has a good compatibility with the acrylic copolymer (A), good curability of the obtained composition of the present invention, and excellent hardness of a coating film formed using the composition. Partially hydrolyzed condensate of silane), ESI40
(Partially hydrolyzed condensate of tetraethoxysilane), MS
It is preferable to use a partially hydrolyzed condensate of a tetraalkoxysilane such as 56, and MS56 is particularly preferable in that the blending amount can be reduced.

In the composition of the present invention, a compound (C) having two or more isocyanate groups as a cross-linking agent is blended with the acrylic copolymer (A) and the silicon compound (B). You.

Examples of the compound having two or more isocyanate groups include aliphatic and aromatic compounds.

Specific examples of the aliphatic polyfunctional isocyanate include hexamethylene diisocyanate for curing at room temperature, and its structure includes a monomer, a buret type, a urezio type, and an isocyanurate type.

For heat curing, there is a block type. Examples of the blocking agent include methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec.
-Butyl alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, benzyl alcohol, furfuryl alcohol, cyclohexyl alcohol, phenol, o-cresol, m-cresol, p-cresol, p-tert-butylphenol, thymol, p-
Examples include nitrophenol and β-naphthol. Examples of the aromatic polyfunctional isocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate,
There are xylene diisocyanate, polymethylene-polyphenyl-polyisocyanate, and isophorone diisocyanate. Also, there are a burette type, a urezio type and an isocyanurate type.

As the curing catalyst (D) mixed with the above isocyanate compound, an organometallic compound is used. In consideration of storage stability and curing activity, compounds containing an S atom in the molecule are preferred.

Specific examples of the organic tin compound include dibutyltin bisisononyl-3-mercaptopropionate, dioctyltin bisisononyl-3-mercaptopropionate, octylbutyltin bisisononyl-3-mercaptopropionate, dibutyltin bisisopropionate. Octyl thioglucolate, dioctyltin bisisooctylthioglucolate, octylbutyltin bisisooctylthioglucolate and the like can be mentioned.

Among the above-mentioned tin compounds, dibutyltin bisisononyl-3-mercaptopropionate and dibutyltin bisisooctylthioglucolate are combined with an isocyanate to improve storage stability, pot life and pot life. It is preferable in that the balance is good and the contact angle of the coating film with water is small.

These curing catalysts (D) may be used alone or in combination of two or more different types or of the same type.

The polyether-modified dimethylpolysiloxane (E) used in the present invention has a polyalkylene oxide structure introduced into one end, both ends or side chains of polydimethylsiloxane.

The polyalkylene oxide structure has an ethylene oxide structural unit as essential, and optionally has 3 carbon atoms.
One to eight or eight or more oxyalkylene structural units may be combined.

The terminal group of the polyalkylene oxide introduced into the terminal or the side chain of the polydimethylsiloxane is not particularly limited, but may be a functional group involved in curing such as an —OH group, and these can also be suitably used. .

The polyether-modified dimethylpolysiloxane (E) used in the present invention is not particularly limited as long as it satisfies the above-mentioned conditions. Specifically, the following general formula (1) or (2) Are preferred examples.

[0069]

Embedded image (PAG is a polyalkylene oxide chain containing an ethylene oxide structural unit, Me represents a methyl group, R represents an alkylene group, and n, X, and Y each represent an integer.) When listed non-limitingly, the compound represented by the general formula (1) is SF84
27, BY16-005, BY16-006, BY6-
007, BY16-008, and those represented by the general formula (2) include SH3746, SF8428, and SH37.
71, BY16-036, BY16-027, BY16
−038, SH8400, SH3749, SH374
8, SF8410 (products of Dow Corning Toray Silicone Co., Ltd.), BYK-306, BYK-30
7, BYK-333 and BYK-325 (all manufactured by BYK Japan KK).

The mercapto group-containing hydrocarbon and / or mercaptosilane (F) which can be used in the present invention
As 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 (OC
H ₃ ) ₃ , (CH ₃ O) ₃ Si—S ₈ —Si (OC
H ₃ ) _{3 and the} like. These may be used alone or in combination of two or more. This compound is
When the isocyanate compound (B) and the curing catalyst (D) are added to a mixed system, the storage stability of the mixture can be improved. Further, the pot life when the above mixture is blended with the acrylic copolymer (A) can also be improved.

The mixing ratio of the acrylic copolymer (A), the silicon compound (B), the isocyanate compound (C), the curing catalyst (D), and the polyether-modified dimethylpolysiloxane (E) is as follows. Combined (A) 100
Parts (parts by weight, hereinafter the same), silicon compound etc. (B) is 2 to 70 parts, isocyanate compound (C) is 0.1 to 30 parts, and curing catalyst (D) is 0.1 to 10 parts. When the polyether-modified dimethylpolysiloxane (E) is 0.0
It can be adjusted so that the content of the mercapto group-containing hydrocarbon and / or the mercaptosilane (F) is 1 to 10 parts, and the content is 0 to 10 parts.

When the amount of the silicon compound or the like (B) is less than 2 parts, the effect of improving the stain resistance of the coating film formed by using the obtained composition becomes insufficient. In addition, the appearance such as the surface gloss of the coating film is reduced, and cracks and the like occur.

The isocyanate compound (C) is contained in 0.1%.
If the amount is less than 1 part, the adhesiveness and curability of the obtained composition will decrease, and if it exceeds 30 parts, the unreacted isocyanate compound or isocyanate in the coating film obtained using this composition The groups remain, causing shrinkage at the time of recoating, and making it difficult for the contact angle of the coating film surface with water to decrease, which adversely affects the improvement of stain resistance.

Further, when the amount of the curing catalyst (D) is more than 10 parts, a coating film formed using the composition tends to decrease appearance such as surface gloss, which is not preferable.

When the amount of the polyether-modified dimethylpolysiloxane (E) is less than 0.01 part, the appearance is insufficient, and when it exceeds 10 parts, the contact angle does not decrease and the stain resistance is hardly developed. .

When the amount of the mercapto group-containing hydrocarbon and / or mercaptosilane (F) exceeds 10 parts,
It is not preferable because the curability decreases.

The compounding amount of the silicon compound (B) is as follows:
The amount is preferably 3 to 60 parts, more preferably 5 to 50 parts.

The amount of the isocyanate compound (C) is preferably 0.5 to 25 parts, more preferably 1 to 25 parts.

The compounding amount of the curing catalyst (D) is as follows.
0.2 to 5 parts is preferable, 0.5 to 5 parts is more preferable, and 0.5 to 3 parts is further preferable.

The amount of the polyether-modified dimethylpolysiloxane (E) is preferably 0.01 to 5 parts.
0.1-5 parts is more preferable.

Further, the compounding amount of the mercapto group-containing hydrocarbon and / or mercaptosilane (F) is as follows:
It is preferably from 0.2 to 5, more preferably from 0.5 to 5 parts.

The curable composition for a top coat of the present invention may contain, for example, titanium oxide, ultramarine, navy blue, zinc white, red iron, lead, white lead, carbon black, transparent iron oxide, etc. Inorganic pigments such as aluminum powder,
Pigments such as organic pigments such as azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, and phthalocyanine pigments; diluents, ultraviolet absorbers, light stabilizers,
Additives such as anti-sagging agents and leveling agents; fibrous materials such as nitrocellulose and cellulose acetate butyrate; epoxy resins, melamine resins, vinyl chloride resins, fluororesins, chlorinated polypropylene, chlorinated rubber, polyvinyl butyral, polysiloxane, etc. Resins and the like may be added as appropriate.

The top coat clear paint containing the above-mentioned curable composition of the present invention as a main component is applied by:
It can be performed by various methods conventionally used, such as immersion, spraying, brush coating, a method using a roll coater or a flow coater. After that, above normal temperature,
Preferably, it can be cured by heating to 55 to 350 ° C.

The thickness of the coating film of the coating material cannot be specified unconditionally because it differs depending on the application, but the thickness of the metallic powder and / or
Alternatively, the thickness of the coating film containing the color pigment is preferably in the range of 10 to 30 μm from the viewpoint of concealment and the like, and the thickness of the top coat clear coating film is preferably 20 to 30 μm from the viewpoint of durability and the like.
A range of 50 μm is preferred.

[0085]

EXAMPLES Next, the curable composition for a top coating composition of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

Production Example 1 (Acrylic copolymer (A) -1)
Production) 30 parts of xylene was charged into a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube and dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, a mixture consisting of 15 parts of styrene (the same applies hereinafter) γ-methacryloxypropyltrimethoxysilane 13 methyl methacrylate 42 n-butyl methacrylate 20 hydroxyethyl methacrylate 10 xylene 25 2,2′-azobisisobutyronitrile 2.8. The solution was dropped at a constant speed over 5 hours by a dropping funnel. After completion of the dropwise addition, 2,2′-azobisisobutyronitrile 0.2 toluene 8 was added dropwise at a constant speed over 1 hour, and the mixture was aged at 110 ° C. for 2 hours and then cooled. To the resin solid content of the obtained resin solution, 3 parts of orthoacetic acid methyl ester was added, and xylene was further added to obtain an acrylic copolymer (A) -1 having a resin solid content concentration of 50%.

The number average molecular weight of the obtained acrylic copolymer was 8,000.

Production Example 2 (Acrylic copolymer (A) -2)
Production) 30 parts of xylene was charged into a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube and dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, a mixture consisting of 15 parts of styrene (the same applies hereinafter) γ-methacryloxypropyltrimethoxysilane 13 methyl methacrylate 47 n-butyl methacrylate 20 hydroxyethyl methacrylate 5 xylene 25 2,2′-azobisisobutyronitrile 2.8. The solution was dropped at a constant speed over 5 hours by a dropping funnel. After completion of the dropwise addition, 2,2′-azobisisobutyronitrile 0.2 toluene 8 was added dropwise at a constant speed over 1 hour, and the mixture was aged at 110 ° C. for 2 hours and then cooled. To the resin solid content of the obtained resin solution, 3 parts of orthoacetic acid methyl ester were added, and xylene was further added to obtain an acrylic copolymer (A) -2 having a resin solid content concentration of 50%.

The number average molecular weight of the obtained acrylic copolymer was 8,200.

Production Example 3 (Acrylic copolymer (A) -3)
Production) 30 parts of xylene was charged into a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube and dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, 15 parts of styrene (the same applies hereinafter) γ-methacryloxypropyltrimethoxysilane 5 methyl methacrylate 38 n-butyl methacrylate 20 n-butyl acrylate 6 hydroxyethyl methacrylate 16 xylene 25 2,2′-azobisisobutyronitrile 2. 8 was dripped at a constant velocity over 5 hours by a dropping funnel. After completion of the dropwise addition, 2,2′-azobisisobutyronitrile 0.2 toluene 8 was added dropwise at a constant speed over 1 hour, and the mixture was aged at 110 ° C. for 2 hours and then cooled. To the resin solid content of the obtained resin solution, 3 parts of orthoacetic acid methyl ester were added, and further, xylene was added to obtain an acrylic copolymer (A) -3 having a resin solid content concentration of 50%.

The number average molecular weight of the obtained acrylic copolymer was 7,800.

Production Example 4 (Acrylic copolymer (A) -4)
Production) 30 parts of xylene was charged into a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube and dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, 15 parts of styrene (the same applies hereinafter) γ-methacryloxypropyltrimethoxysilane 20 methyl methacrylate 35 n-butyl methacrylate 20 n-butyl acrylate 8 hydroxyethyl methacrylate 2 xylene 25 2,2′-azobisisobutyronitrile 4. 8 was dripped at a constant velocity over 5 hours by a dropping funnel. After completion of the dropwise addition, 2,2′-azobisisobutyronitrile 0.2 toluene 8 was added dropwise at a constant speed over 1 hour, and the mixture was aged at 110 ° C. for 2 hours and then cooled. To the resin solid content of the obtained resin solution, 3 parts of orthoacetic acid methyl ester was added, and xylene was further added to obtain an acrylic copolymer (A) -4 having a resin solid content concentration of 50%.

The number average molecular weight of the obtained acrylic copolymer was 5,400.

Examples 1 to 7 and Comparative Examples 1 to 5 The components shown in Tables 1 and 2 were mixed to prepare a topcoat clear paint.

Coating of a topcoat clear paint A steel plate that has been subjected to degreasing and phosphate conversion treatment is coated with an epoxyamide-based cationic electrodeposition primer and an intermediate coating surfacer, and an acrylic melamine resin paint (Supertech F50 Black Japan Paint Co., Ltd.
Was coated and baked at 180 ° C. for 30 minutes to prepare a base coat.

The top coat clear paint prepared in Table 1 was applied to the obtained base coat, set for 30 minutes, and baked at 70 ° C. for 30 minutes. Dry film thickness is 30 ~
It was 40 μm.

[Appearance] The gloss and sharpness were visually evaluated comprehensively.

○ indicates good, and △ indicates slightly poor.

[Adhesion] After the obtained coating film was allowed to stand at room temperature for 7 days, the grid adhesion was measured in accordance with JIS K5400. "10" indicates no peeling, and "0"
Indicates that it was completely removed.

[Contact Angle to Water] After leaving the obtained coating film at room temperature for 7 days, using a Kyowa Interface Science Model CA-S150, a water droplet of about 0.03 ml of ion-exchanged water was dropped on the coating film surface. Then, the static contact angle after 3 minutes at 23 ° C. was measured.

[Stain resistance (difference in lightness)] L * a at the beginning of exposure
The lightness represented by the * b * color system was measured with a colorimeter (CR-300 manufactured by Minolta), and an outdoor exposure of 30 ゜ on the south side was conducted in Settsu City, Osaka Prefecture for 3 months. L * a * b * after exposure was measured, and the difference in lightness (ΔL * value) before and after exposure was used as a measure of contamination. In addition, a smaller value indicates that the sample is contaminated (a larger value indicates that the stain resistance is superior).

[0102]

[Table 1]

[Table 2]

[0103]

According to the present invention, the curable composition for a topcoat paint comprises:
It has curability at room temperature or under heating, and a coating film (that is, a coating material) from the composition has excellent weather resistance as well as a coating film from an acrylic silicone resin paint, and also has excellent stain resistance. , Adhesiveness and the like. Therefore, it can be suitably used for various applications requiring the above-described performance, for example, for construction and automobiles.

Claims (6)

[Claims] 1. A compound of the general formula (I): (Wherein, R ¹ is a hydroxyl group or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or a monovalent hydrocarbon group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group. , A represents an integer of 0 to 2) with respect to 100 parts by weight of an acrylic copolymer (A) containing a reactive silyl group and a hydroxyl group bonded to a carbon atom represented by the following general formula (II): Embedded image (Wherein, R ³ is a monovalent hydrocarbon group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group, and R ⁴ is an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms. A monovalent hydrocarbon group selected from
Represents 0 or 1. )) And / or a hydrolytic condensate thereof (B) in an amount of 2 to 70 parts by weight, (C) 0.1 to 30 parts by weight of a compound having two or more isocyanate groups, and (D) a curing catalyst. A curable composition for a topcoat comprising 1 to 10 parts by weight and (E) 0.01 to 10 parts by weight of a polyether-modified dimethylpolysiloxane. 2. The acrylic copolymer (A) contains 3-90% by weight of a monomer unit having a reactive silyl group bonded to a carbon atom represented by the general formula (I) in a molecule. The curable composition according to claim 1, which is a copolymer. 3. The composition according to claim 1, wherein the curing catalyst (D) is an organometallic compound. 4. The composition according to claim 3, wherein the organometallic compound is a tin compound containing an S atom in a molecule. 5. The composition according to claim 1, further comprising a mercapto group-containing hydrocarbon and / or mercaptosilane (F). 6. A coated product obtained by applying a top coat clear paint to a coating surface to which a paint containing a metallic powder and / or a color pigment is applied, wherein the top coat clear paint is applied. A coated article comprising, as a main component, the curable composition for a coating according to any one of the above.