JPH0699668B2 - Coating composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is directed to the heat resistance of the surface of metal, ceramics, glass, cement, plastics, wood, paper, fiber, etc.
The present invention relates to a coating composition for coating, which is excellent in abrasion resistance, chemical resistance, water resistance, weather resistance, etc. and is suitable for forming a thick coating film having high hardness and high gloss.

(B) Conventional technology The surface of various molded products such as metals and ceramics is coated with a composition comprising a silicone-based compound and a silicone-modified acrylic resin to provide beauty or abrasion resistance,
Chemical resistance, corrosion resistance, weather resistance, water resistance, glare resistance, etc. have been improved. For example, JP-A-60-
Japanese Patent No. 135465 discloses a coating composition comprising a dispersion liquid of organotrihydroxysilane and colloidal silica and a silicone-modified acrylic resin. This composition is simply obtained by mixing a dispersion of methyltriethoxysilane hydrolyzed with water in an aqueous silica sol and a silicone-modified acrylic resin containing an alkoxy group in a compatible solvent. Therefore, the cured film obtained by applying the composition cannot be said to be chemically homogeneous. Since the silicone component and the silicone-modified acrylic resin cure independently, they have the effect of preventing glare, but the coating film lacks water resistance, chemical resistance, adhesion, scratch resistance, and smoothness.

JP-A-61-277901 discloses a composition comprising a hydrolyzate of orthoethyl silicate and a vinyl polymer containing a silyl group as an antiglare agent for a synthetic resin plate. This composition is essentially the same as the composition described above, except that the polysiloxane consists of ethyl silicate. Therefore, a cured film obtained by applying the composition is inhomogeneous, and although it has an effect of preventing glare, it lacks water resistance, chemical resistance, adhesion, scratch resistance, and smoothness as a coating film. .

JP-A 64-1769 discloses an organopolysiloxane,
A coating composition comprising a zirconium compound and a silyl group-containing vinyl resin is disclosed. In this composition, the zirconium compound forms a cross-linking part between the organopolysiloxane and the silyl group-containing vinyl resin, and gives a copolymer in which the organopolysiloxane and the silyl group-containing vinyl resin are chemically complexed. . Therefore, the cured film obtained by applying the composition is homogeneous and has excellent smoothness,
Excellent chemical resistance and gloss. In addition, since the composition contains β-diketones that act as a stabilizer, the composition has good storage stability. However, since this composition is a copolymer of an organopolysiloxane and a vinyl resin containing a silyl group, the silanol content per copolymer molecule is small, that is, the crosslink density is small. Therefore, not only the adhesiveness with the substrate is poor, but also the hardness of the coating film obtained by curing is low.

Further, the β-diketones or β-ketoesters used during the hydrolysis of the zirconium compound form a coloring chelate compound with a trace amount of metal ions, particularly iron ions, and therefore, during the preparation and storage of the composition. Alternatively, raw materials, containers, instruments, etc. used when forming the coating film are limited.

(C) Problem to be Solved by the Invention The present invention is to solve the above-mentioned conventional problems, and the purpose thereof is to provide metal, ceramics, glass,
A coating composition for coating the surface of cement, plastics, wood, paper, fibers and the like, which is to provide a coating composition having the following properties.

For coating compositions that have excellent transparency and gloss, high hardness, and excellent adhesion to base materials, alkali resistance, acid resistance, boiling water resistance, solvent resistance, etc. A coating composition that can form an excellent coating film, does not require long-term curing treatment at high temperature when preparing a coating film, and even when forming a coating film with a relatively thick film thickness, tarac and the like occur. A coating composition that does not have discoloration, blistering, cracking, etc. even when exposed outdoors for a long time.

(D) Means and Actions for Solving the Problems The coating composition for coating of the present invention comprises (1) (a) the general formula RSi (OR ¹ ) ₃ (wherein R represents a carbon number of 1).
To 8 organic groups, R ¹ represents an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms) and an organoalkoxysilane represented by the formula (1) and / or a partial condensate thereof is 100 in terms of organoalkoxysilane. (B) 10 to 300 parts by weight of a silyl group-containing vinyl resin having at least one silyl group having a silicon atom bonded to a hydrolyzable group at the terminal or side chain in one molecule of the polymer, (c) 10 to 70 parts by weight of water, (d) a tetraalkyl silicate represented by the general formula Si (OR ² ) ₄ (wherein R ² represents an alkyl group having 1 to 4 carbon atoms).
0.5 to 30 parts by weight, (e) the general formula Al (OR ³⁾ n [OC (R ⁴⁾ = CHCOR ^5] _3-n
(Wherein R ³ and R ⁴ are alkyl groups, R ⁵ is an alkyl group or an alkoxy group, n is an integer of 0 to 3), and a partial hydrolyzate of the aluminum compound. 0.01 to 30 at least one selected
The above object is achieved by blending parts by weight, and (f) an appropriate amount of a solid content adjusting agent.

The organoalkoxysilane and / or its partial condensate [component (a)] used in the composition of the present invention has the general formula RS
Alkoxy group-containing partial condensate obtained by condensing an alkoxy group-containing silicon compound represented by i (OR ¹ ) ₃ and an alkoxy group-containing silicon compound represented by the general formula RSi (OR ¹ ) under hydrolysis conditions Is.

In the above formula, R is an organic group having 1 to 8 carbon atoms, and R ¹ is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms. If the carbon number of R and R ¹ is too large, the hydrolysis rate described below becomes extremely slow, and in some cases hydrolysis hardly progresses. The R is a methyl group,
Alkyl group such as ethyl group, propyl group, butyl group; aryl group such as phenyl group, tolyl group, xylyl group; cycloalkyl group such as cyclohexyl group; other γ-chloropropyl group, vinyl group, γ-glycidoxypropyl Group, γ-methacryloyloxypropyl group, γ-mercaptopropyl group, γ-aminopropyl group, 3,4-epoxycyclohexyl group and the like. Examples of R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, an acetyl group and the like. Examples of such organoalkoxysilanes include, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, Phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γmethacryloxytrimethoxysilane, Examples include γ-aminopropyltrimethoxysilane and 3,4-epoxycyclohexylethyltrimethoxysilane. Preferably, methyltrimethoxysilane and / or methyltriethoxysilane are used. These organoalkoxylanes can be used alone or in combination of two or more kinds.

The reaction for producing a partial condensate obtained by condensing the above-mentioned organoalkoxysilane under hydrolysis conditions can be carried out by a production method known per se, that is, by adding water to the above-mentioned organoalkoxysilane and allowing it to condense. it can.

The silyl group-containing vinyl resin (component (b)) used in the composition of the present invention has at least one silyl group having a silicon atom having a hydrolyzable group bonded at the terminal or side chain in one molecule of the polymer. It is a vinyl resin containing silyl groups. For example, such a silyl group-containing vinyl resin has the general formula (a) (Here, R ⁶ is a hydrolyzable group such as a halogen atom, an alkoxy group, an acyloxy group, an aminoxy group, a phenoxy group, a thioalkoxy group, and an amino group, a hydrogen atom or an organic group having 1 to 8 carbon atoms, R ^{7 8} is a divalent hydrocarbon group, R ⁹ is a hydrogen atom or a monovalent hydrocarbon group, and n is an integer of 1 to 3) and an acryloxy-functional silane represented by the general formula (b) (Wherein R ¹⁰ is a hydrogen atom or substituted or unsubstituted n
Represents a group selected from the group consisting of a valent aliphatic hydrocarbon residue and a substituted n-valent aliphatic hydrocarbon residue having at least one ether bond, R ¹¹ is a hydrogen atom or a lower alkyl group, n is an integer of 1 to 4) or by copolymerization of a radically polymerizable acrylate monomer represented by (Here, R ¹² is a hydrolyzable group such as a halogen atom, an alkoxy group, an acyloxy group, an aminoxy group, a phenoxy group, a thioalkoxy group and an amino group, R ¹³ is a hydrogen atom or an organic group having 1 to 8 carbon atoms, It can be produced by reacting a hydrosilane compound represented by (n is an integer of 1 to 3) with a vinyl polymer having a carbon-carbon double bond, and the production method thereof is not particularly limited.

Here, as the acryloxy-functional silane represented by the general formula (a), for example, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane and γ- Methacryloxypropyltriisopropoxysilane and the like can be mentioned.

One or more selected from the group consisting of these are used.

Examples of the radical polymerizable monomer represented by the general formula (b) include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, t-butyl acrylate, 2-hydroxyethyl acrylate, and acrylic acid 2 −
Hydroxypropyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-methacrylate
Butyl, isobutyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methoxydiethylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxytetraethylene methacrylate and monoacrylates such as allyl methacrylate. Monomers; Diacrylate monomers such as ethylene glycol dimethacrylate, diethylene glycol methacrylate, 1,3-butylene glycol diacrylate and 1,3-butylene glycol dimethacrylate; trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate and tetramethylolmethane triacrylate. Such as triacrylate Nomar; and tetraacrylate monomers such as tetramethylolmethane tetraacrylate and the like.

One or two or more selected from the group consisting of these are used.

A hydrolyzable silyl group-containing acrylic resin is obtained by mixing at least one of these acryloxy-functional silanes and at least one of radically polymerizable monomers in a suitable solvent and copolymerizing with a radical polymerization initiator. be able to.

Examples of the radical polymerization initiator include benzoyl peroxide, dichlorobenzoyl peroxide, di-t-
Perester compounds such as butyl peroxide, 2,5-di (peroxide benzoate) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene, t-butylperbenzoate; azobisisobutyronitrile and dimethylazo Azo compounds such as butyrate; and organic peroxides.

As the hydrosilane compound represented by the general formula (C),
For example, halogenated silane compounds such as methyldichlorosilane, ethyldichlorosilane, phenyldichlorosilane and trichlorosilane; methyldimethoxysilane, methyldiethoxysilane, ethyldimethoxysilane, ethyldiethoxysilane, phenyldimethoxysilane, trimethoxy. Alkoxysilane compounds such as silane and triethoxysilane; Acyloxysilane compounds such as methyldiacetoxysilane, phenyldiacetoxysilane, triacetoxysilane; and aminosilane compounds such as methyldiaminoxysilane, triaminoxysilane, and triaminosilane. To be One or more selected from the group consisting of these are used.

The vinyl polymer having a carbon-carbon double bond is selected from styrenes, α-methylstyrene, vinyl chloride, vinyl acetate, etc. in addition to those having no hydroxyl group among the acrylates represented by the general formula (b). Carbon obtained by copolymerizing one or more vinyl compounds with a conjugated diene compound such as butadiene, isoprene and chloroprene, and / or an acrylic acid derivative having a carbon-carbon double bond not involved in polymerization -Vinyl polymers having a carbon double bond are preferred.

At least one of these hydrosilane compounds is used as carbon-
A hydrolyzable silyl group-containing vinyl resin (component (b)) can be obtained by adding it to a vinyl polymer having a carbon double bond by an appropriate method.

Specific examples of the hydrolyzable silyl group-containing vinyl resin used in the present invention include Zemlac and Cyril manufactured by Kaneka Fuchi Chemical Co., Ltd .; Silicone acrylic varnish manufactured by Toshiba Silicone Co., Ltd.

The mixing ratio of the silyl-containing vinyl resin (component (b)) is 10 parts with respect to 100 parts by weight of organoalkoxysilane.
˜300 parts by weight, preferably 15 to 200 parts by weight. When the amount of the silyl group-containing vinyl resin is less than 10 parts by weight, the resulting coating film has insufficient chemical resistance, and a thick film is prone to cracks. On the other hand, if it exceeds 300 parts by weight, scratch resistance,
It has poor heat resistance and lacks storage stability.

Water (component (c)) used in the composition of the present invention is an essential component for the hydrolysis reaction of the organoalkoxysilane (component (a)) and the silyl group-containing vinyl resin (component (b)). The ratio of water used is 10% organoalkoxysilane.
It is 10 to 70 parts by weight, preferably 20 to 60 parts by weight, relative to 0 parts by weight. If it is less than 10 parts by weight, the coating film may not be sufficiently cured even if the composition obtained is applied. On the other hand, if the blending ratio exceeds 70 parts by weight, the storage stability of the composition is lowered, which is not preferable.

As the above-mentioned required water, tap water, distilled water, ion-exchanged water or the like is used. Distilled water or ion-exchanged water is preferably used.

The water may be mixed with a desolvent for controlling or promoting the hydrolysis reaction.

Such catalysts include mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid,
Any of the organic acids such as formic acid, oxalic acid, acetic acid, etc. can be used.

The tetraalkyl silicate represented by the general formula Si (OR ² ) ₄ (component (d)) used in the composition of the present invention improves the hardness of the cured coating film obtained by coating the composition, or Improves adhesion with the substrate. In particular, it works to improve water resistance.

In the above formula, R ² represents an alkyl group having 1 to 4 carbon atoms.

Such alkyl silicates include tetramethyl silicate, tetraethyl silicate, tetra-n-propyl silicate, chitra-i-propyl silicate,
Examples thereof include tetra-n-butyl silicate, tetra-i-butyl silicate and tetra-sec-butyl silicate.

The compounding ratio of the tetraalkyl silicate is 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the organoalkoxysilane. If it is less than 0.5 part by weight, the hardness and water resistance of the obtained coating film will be low, while if it exceeds 30 parts by weight, cracks will be likely to occur in the obtained coating film.

The general formula used in the composition of the present invention is Al (OR ³ ) n [OC (R
⁴ ) = CHCOR ⁵ ] _3-n , the aluminum compound represented by the formula, and the partial hydrolyzate of the aluminum compound (component (e)) are the above-mentioned organoalkoxysilanes (component (a)) and silyl group-containing vinyl resins ( It acts as a reaction accelerator during the hydrolysis reaction of component (b)). Further, it acts to form a cross-linking site between the organoalkoxysilane and the silyl group-containing vinyl resin. Therefore, the aluminum compound may be added at the time of the hydrolysis reaction, or may be added after the completion of the hydrolysis reaction.

In the above formula, R ³ and R ⁴ are alkyl groups, R ⁵ is an alkyl group or an alkoxy group, and n is an integer of 0 to 3. Examples of such aluminum compounds include tri-i-propoxyaluminum, tri-n-propoxyaluminum, tri-sec-butoxyaluminum, tri-n-butoxyaluminum, sec-butoxyaluminum isopropylate, tri-tert-butoxyaluminum, Ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetonate), aluminum tris (acetylacetonate),
Examples thereof include aluminum monoacetylacetonate bis (ethylacetonate) and a partial hydrolyzate of the aluminum compound. These aluminum compounds and partial hydrolysates of the aluminum compounds may be used alone or in combination of two or more kinds.

The above-mentioned partial hydrolyzate of the aluminum compound can be obtained by adding water to the hydrophilic organic solvent containing the aluminum compound to the extent that precipitation or gel does not occur.

The mixing ratio of the aluminum compound and a partial hydrolyzate of the aluminum compound is 0.01 to 30 parts by weight, preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the organoalkoxysilane.
20 parts by weight. If it is less than 0.01 part by weight, the hardness and chemical resistance of the resulting coating film are low, while if it exceeds 30 parts by weight, the stability of the composition over time deteriorates. Further, the obtained coating film is likely to be cracked.

The solid content adjusting agent (component (f)) used in the composition of the present invention not only functions as a diluent for adjusting the solid content concentration of the present invention, but also can be applied to various coating methods. The storage stability of is improved.
Examples of the solid content adjusting agent include alcohol solvents, aromatic solvents, ketone solvents, ester solvents, and polyhydric alcohol solvents. For example, methanol,
Ethanol, n-propanol, i-propanol, n
-Butanol, i-butanol, sec-butanol, benzene, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, ethylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve and the like can be mentioned.

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

The blending ratio of the solid content modifier (compound (f)) is viscosity adjustment,
It is appropriately determined according to the purpose of dilution or the like and is not particularly limited. However, it is usually preferred to adjust the total solids concentration in the composition to be 10 to 50% by weight, preferably 15 to 40% by weight. If it is less than 10% by weight, the solid content is too low and pinholes are likely to occur in the coating film obtained by coating with the composition obtained, and the various properties of the coating film may not be exhibited. On the other hand, if it exceeds 50% by weight, the solid content concentration becomes too high, and the storage stability of the composition deteriorates.

The composition of the present invention may further contain various additives, if necessary.

For example, an extender pigment or a coloring pigment may be added to be used as a colored enamel, or an appropriate filler may be added,
It can also be used as a paint for forming a rust preventive film, an electric insulating film, a conductive film, a far infrared radiation film, a far infrared absorption film, an ultraviolet absorption film, and the like.

In addition to these, various conventionally known additives such as various surfactants, silane coupling agents, titanium coupling agents, acetylacetone, dyes and the like may be contained.

In preparing the composition of the present invention, (a) to (f)
The components may be mixed at once, or the components (a) to (c) and the component (f) may be mixed and then mixed with the components (d) to (e), or the components (a) and (c). After mixing the components, the (b) component,
The components (d) to (f) may be mixed, and (a) to (c).
After mixing a part of the component (e) with the component, the component (d), the rest of the component (e) and the component (f) may be mixed, and the preparation method is not particularly limited.

A desired coating film is formed by applying and curing the coating composition for coating of the present invention on various substrates. Examples of the target substrate include metals, ceramics, cement, glass, plastics, paper, fibers and wood. The coating film can be cured under a relatively mild condition of about 80 to 200 ° C for 5 to 60 minutes, and a relatively thick coating film can be formed without causing cracks or peeling during curing. Is possible.

The composition of the present invention comprises a polysiloxane derived from an organoalkoxysilane (component (a)), a silyl group-containing vinyl resin (component (b)), a tetraalkyl silicate (component (d)) and an aluminum compound (component). Since it has a form in which it is chemically and firmly bonded on the base material during coating and curing together with (e), the adhesion to the base material is not impaired. Therefore, this coating film has remarkably excellent characteristics as compared with a coating film formed from a chemical copolymer of polysiloxane and vinyl resin containing a silyl group.

Thus, by using the coating composition of the present invention, having a gloss, high hardness and weather resistance, solvent resistance, acid resistance,
A coating film having excellent alkali resistance and water resistance can be formed.

(E) Examples The present invention will be described below with reference to Examples. In the examples, all parts are parts by weight and all% are% by weight.

Example 1 (a) Preparation of coating composition for coating In a reaction vessel equipped with a reflux condenser and a stirrer, 100 parts of methyltrimethoxysilane and Kaneka Zemlac (manufactured by Kanegafuchi Chemical Industry Co., Ltd .: containing trialkoxysilyl group) Acrylic polymer, solid 50%) 100 parts, isopropanol 20 parts, water 40
A portion was charged and heated to 70 ° C. with stirring and reacted for 8 hours. Next, 40 parts of isopropanol, 2 parts of aluminum tris (acetylacetonate), and 4 parts of tetramethyl silicate were added to obtain a coating composition A for coating.

(B) Evaluation of coating composition for coating The coating composition A obtained in section (a) was sprayed onto a cold-rolled stainless steel plate (JIS G4305 SUS-CP) using a spray device to obtain a dry coating film of about Apply to 20 μm.
This was heated at 180 ° C. for 20 minutes, and the obtained cured coating film was evaluated for the following items. The composition of the coating material and the obtained results are shown in Table 1 and Table 2, respectively, together with the evaluation results of the coating composition for coating obtained in Examples 2 to 5 and Comparative Examples 1 to 5 described later.

[Appearance of coating film] The surface condition is evaluated by visual observation.

[Adhesiveness] Evaluate with JIS5400 cross-cut.

[Hardness] The pencil hardness of JIS5400 is evaluated.

[Solvent resistance] Dip methanol into gauze and observe the state after rubbing test the coating film 30 times.

[Boiling resistance] Observe the condition after soaking in boiling water at 98 ° C for 8 hours.

[Acid resistance] 1 ml of a 5% aqueous solution of sulfuric acid was dropped on the coating film, and the mixture was allowed to stand for one day in a petri dish with a lid, washed with water, and the state was observed.

[Alkali resistance] 1 ml of a 5% aqueous sodium hydroxide solution was dropped on the coating film, and the mixture was allowed to stand for one day in a petri dish with a lid, washed with water, and the state was observed.

[Weather resistance] According to JIS K5400, a 1000 hour irradiation test was performed with a weatherometer and the state was observed.

Examples 2 to 5 Using the compositions and reaction conditions shown in Table 1, operation was carried out according to Example 1 to obtain coating compositions B to E for coating. The composition and evaluation results of the obtained coating composition for coating are shown in Table 1 and Table 2, respectively.

Comparative Examples 1 to 5 Coating compositions F to J for coating were obtained by the same operation as in Example 1 with the compositions and reaction conditions shown in Table 1. The composition and the evaluation results of the obtained coating composition for coating are shown in Table 1 and Table 2, respectively.

Example 6 Using 100 parts of the coating composition A for coating obtained in Example 1 as a binder, titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., Taipaque R-
380) 30 parts were mixed and dispersed in a sand mill for 1 hour,
A coating composition K for coating was obtained. Next, the obtained coating composition K for coating was applied onto a slate plate (JIS A5403) using a spraying device so that the dry coating film would be about 50 μm, and the temperature was 150 ° C.
And heated for 20 minutes to form a cured coating film. These cured coating films were evaluated for the evaluation items shown in Example 1. The results are shown in Table 3 together with the evaluation results of the coating compositions for coating obtained in Examples 7 to 10 and Comparative Examples 6 to 10 described later.

Examples 7 to 10 Coating compositions for coating were prepared in the same manner as in Examples 6 to 10 except that coating compositions B to E prepared in Examples 2 to 5 were used instead of coating composition A for coating. Products L to O were obtained and evaluated in the same manner. The results are shown in Table 3.

Examples 6 to 10 Coating composition P for coating was prepared in the same manner as in Example 6 except that coating compositions F to J prepared in Comparative Examples 1 to 5 were used instead of the coating composition for coating. ~ T was obtained and evaluated in the same manner. The results are shown in Table 3.

(F) Effect of the Invention According to the present invention, as shown in the above Examples and the like, a coating composition for coating which can easily form a coating film having excellent properties on the surface of a substrate such as a metal or ceramic substrate. Will be provided. In particular, the coating film obtained by using the coating composition for coating of the present invention has high hardness, excellent scratch resistance, and gloss, and is extremely excellent in weather resistance, water resistance, chemical resistance and the like. It is excellent. It maintains a high gloss even under conditions where it is easily corroded or is left outdoors, and does not cause discoloration or deterioration. It has excellent properties that cannot be obtained with conventional coating compositions for coating. Therefore, for example, its usefulness is extremely great as a coating material for coating outer wall materials exposed to sunlight, equipment used under conditions where they are easily corroded, and building materials that require good cosmetic properties.

Claims (1)

[Claims] (A) General formula RSi (OR ¹ ) ₃ (wherein R is an organic group having 1 to 8 carbon atoms, R ¹ is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms). Group)) and / or a partial condensate of the organoalkoxysilane represented by the formula (1), and (b) a silyl group having a silicon atom bound to a hydrolyzable group at the terminal or side chain. At least 1 in the polymer molecule
10 to 300 parts by weight of silyl group-containing vinyl resin, (c) 10 to 70 parts by weight of water (d) General formula Si (OR ² ) ₄ (wherein R ² represents an alkyl group having 1 to 4 carbon atoms) ) Tetraalkyl silicate represented by
0.5 to 30 parts by weight, (e) the general formula Al (OR ³⁾ n [OR (R ⁴⁾ = CHCOR ^5] _3-n
(Wherein R ³ and R ⁴ are alkyl groups, R ⁵ is an alkyl group or an alkoxy group, n is an integer of 0 to 3), and a partial hydrolyzate of the aluminum compound. 0.01 to 30 at least one selected
A coating composition for coating comprising 1 part by weight, and (f) an appropriate amount of solid content modifier.