JP2003313497A - Water-based coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition which has good curability and forms a coating film excellent in stain resistance, hot-water resistance, alkali resistance, etc. <P>SOLUTION: The water-based coating composition contains (I) an aqueous dispersion obtained by neutralizing hydrolytic condensate of 100 pts.mass (a) organosilane represented by formula (1): R<SP>1</SP><SB>n</SB>Si(OR<SP>2</SP>)<SB>4-n</SB>[wherein R<SP>1</SP>is a 1-8C organic group; R<SP>2</SP>is a 1-5C alkyl group; and n is 1 or 2] and/or condensate of a partial hydrolyzate thereof with 5-200 pts.mass (b) silyl-containing vinyl resin having hydrolyzable silyl groups or OH-bonded-Si-containing silyl groups and having an acid value of 20-150 mgKOH/g with a neutralizing agent and adding water to the neutralized product and (II) colloidal silica. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention comprises an aqueous dispersion of a specific organic-inorganic composite resin and colloidal silica, has good curability, and has stain resistance, hot water resistance, weather resistance and solvent resistance. , An aqueous coating composition capable of forming a coating film having excellent alkali resistance and the like.

[0002]

2. Description of the Related Art A coating film containing an organic-inorganic composite resin obtained by hydrolyzing and condensing an organosilane and / or a partial hydrolyzed condensate thereof and a silyl group-containing vinyl resin as a binder has weather resistance and It is excellent in stain resistance and is less likely to crack like a coating film using an organopolysiloxane-based inorganic resin as a binder, and thus the above-mentioned coating composition using an organic-inorganic composite resin as a binder is attracting attention. It has become to. However, many of such coating compositions are organic solvent-based coatings, which is not preferable from the viewpoint of air pollution and resource saving, and when the amount of organic resin used for preventing cracks is increased, the resulting coating composition is obtained. There is a problem that the stain resistance, weather resistance, solvent resistance, etc. of the film are lowered. In addition, recently, the development of water-based paints using organic-inorganic composite resins as binders has been made, and the problem of organic solvents has been solved, but in the case of water-based paints, drying is slow and curing is insufficient. Therefore, there is a problem that the hardness, stain resistance, solvent resistance, alkali resistance, etc. of the coating film are inferior.

[0003]

SUMMARY OF THE INVENTION The present invention has been made against the background of the problems of the prior art as described above. By using a specific organic-inorganic composite resin aqueous dispersion and colloidal silica, the curability is improved. Also, stain resistance, hot water resistance,
It is an object of the present invention to provide an aqueous coating composition capable of forming a coating film excellent in weather resistance, solvent resistance and the like.

[0004]

That is, the present invention provides (i)
(A) Formula (1), R ¹ _n Si (OR ² ) _4-n [In the formula, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] 100 parts by mass of organosilane and / or its partial hydrolyzed condensate, and (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20 to 150 mgKOH / G of silyl group-containing vinyl resin 5 to 200 parts by mass, a water-dispersion liquid obtained by neutralizing a hydrolysis condensation reaction product with a neutralizing agent and adding water, and (II) colloidal silica The present invention relates to a water-based coating composition containing:

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Each component of the water-based coating composition of the present invention will be described. Component (i) First, each component used for producing the component (i), which is an organic-inorganic composite resin aqueous dispersion, will be described. Component (a) The component (a) is represented by the formula (1), R ¹ _n Si (OR ² ) _4-n [wherein, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] The organosilane and / or its partial hydrolysis-condensation product shown by these. In the above formula, examples of the organic group as R ¹ include an alkyl group, a cycloalkyl group, an aryl group, a vinyl group and the like. Here, the alkyl group may be linear or branched. Examples of the alkyl group include a methyl group, an ethyl group, and n.
Examples thereof include alkyl groups such as -propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group, and octyl group. Preferred alkyl groups have 1 to 4 carbon atoms.

Preferable examples of the cycloalkyl group include a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like. Examples of the aryl group include a phenyl group and the like. Each of the above functional groups may optionally have a substituent. Examples of such a substituent include a halogen atom (for example, a chlorine atom, a bromine atom, a fluorine atom, etc.), a (meth) acryloyl group, a mercapto group, an alicyclic group and the like. The alkyl group as R ² may be linear or branched. Examples of such an alkyl group include a methyl group, an ethyl group,
n-propyl group, i-propyl group, n-butyl group, i-
A butyl group, an s-butyl group, a t-butyl group, a pentyl group and the like can be mentioned, and a preferable alkyl group has 1 to 2 carbon atoms.
It belongs to an individual.

Specific examples of the organosilane represented by the above formula (1) include, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n. -Propyltriethoxysilane, i-
Propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ
-Chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3,3,3-
Trifluoropropyltrimethoxysilane, 3,3,3
-Trifluoropropyltriethoxysilane, cyclohexyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxy Examples include silane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, and dimethyldipropoxysilane.
Preferred are methyltrimethoxysilane, methyltriethoxysilane, and dimethyldimethoxysilane.

These organosilanes may be used alone or in combination of two or more.
The component (a) may be a partially hydrolyzed condensate of the organosilane described above. The polystyrene equivalent weight average molecular weight of the condensate is, for example, 300 to 5,000, preferably 500 to 3,000 is suitable. By using the condensate having such a molecular weight, the storage stability is not deteriorated, A coating film with good adhesion can be obtained. Also,
The partially hydrolyzed condensate of organosilane has at least one —OH group or —OR ² group bonded to a silicon atom, preferably 3 to 30 groups. Specific examples of such condensates include SH6018 manufactured by Toray Dow Corning Co., SR2402, and DC303 as commercial products.
7, DC3074; KR-211 manufactured by Shin-Etsu Chemical Co., Ltd.
Or KR-212, KR-213, KR-214, KR
-216, KR-218; TSR manufactured by Toshiba Silicone Co., Ltd.
-145, TSR-160, TSR-165, YR-
3187 etc. are mentioned. In the present invention, the component (a) includes an organosilane having an n value of 1 in the above formula and / or a partial hydrolyzed condensate thereof (a-1), and an organosilane having an n value of 2 and / or a partial hydrolysis thereof. Condensate (a-2)
A mixture having a mass ratio of (50:50 to 100: 0), preferably (60:40 to 95: 5), reacts stably during the hydrolysis-condensation reaction and has good crack resistance. It is desirable because a film can be obtained.

Component (b) The component (b) contains at least one hydrolyzable silyl group at the terminal or side chain of the vinyl resin, or at least one silyl group having a silicon atom bonded to a hydroxyl group in one resin molecule, preferably Has two or more and an acid value of 20 to 150 mg KO
H / g, preferably with a molecular weight of, for example, about 1000
It is a vinyl resin of up to 50,000. The silyl group is
Formula (2), —SiX _P (R ³ ) _(3-P) [In the formula, X is a hydrolysis of an alkoxy group, an acyloxy group, a halogen atom, a ketoximate group, a mercapto group, an alkenyloxy group, a phenoxy group, or the like. R ³ is hydrogen or an alkyl group having 1 to 10 carbon atoms,
It is a monovalent hydrocarbon group such as an aryl group or an aralkyl group, and P is an integer of 1 to 3. ] Is shown. The alkyl group in the alkoxy group is, for example, suitably an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, and may be linear or branched. As such an alkyl group, specifically, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group,
Preferable examples are t-butyl group and pentyl group. Preferable examples of the acyloxy group include an acetyl group and a benzoyloxy group.

Preferable examples of the halogen atom include chlorine atom, bromine atom, fluorine atom and the like. The ketoximate group generally has (R ³ ) ₂ —C═NO
-(In the formula, R ³ is the same as in the case of the above formula (2)), and preferable examples thereof include an acetoxymate group and a group such as dimethyl ketoximate. . Preferable examples of the alkenyl group in the alkenyloxy group include alkenyl groups corresponding to the above alkyl groups. 1 to 10 carbon atoms as R ³
The alkyl group of may be linear or branched. Specific examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group,
Preferable examples are n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group and the like. Examples of the aryl group include, for example, a phenyl group and the like. The aralkyl group is a group having a structure in which a hydrogen atom of an alkyl group is substituted with an aryl group, and the range of the alkyl group and the aryl group is
As above.

The silyl group-containing vinyl resin is, for example, represented by the formula (3), (X) _P (R ³ ) _(3-P) Si—H [wherein, X, R ³ and p are represented by the above formula (2). ) Has the same meaning. ] It manufactures by making the hydrosilane compound shown by these and the vinyl resin which has a carbon-carbon double bond react according to a conventional method. In addition, as the above-mentioned hydrosilane compound, for example, methyldichlorohydrosilane, methyldiethoxyhydrosilane, methyldiacetoxyhydrosilane and the like are mentioned as typical ones. The amount of the hydrosilane compound used is appropriately 0.5 to 2 times the molar amount of the carbon-carbon double bond contained in the vinyl resin.

The vinyl resin contains (meth) acrylic acid, carboxylic acids such as itaconic acid and fumaric acid, or acid anhydrides such as maleic anhydride as essential vinyl monomers, and further contains methyl (meth) acrylate. And (meth) acrylic acid esters such as ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, 2 Hydroxyl group-containing vinyl monomers such as hydroxypropyl (meth) acrylate and 2-hydroxyvinyl ether; 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano- 4-
Polymerizable light stabilizers such as (meth) acryloylamino-2,2,6,6-tetramethylpiperidine; (2-hydroxy-4-((meth) acryloyloxyethoxy) benzophenone and other polymerizable ultraviolet absorbers; acrylonitrile , Copolymers with other vinyl monomers selected from the group consisting of styrene, α-methylstyrene, vinyl acetate, vinyl propionate and the like are preferable, and allyl (meth) acrylate or diallyl is used during the production of the copolymer. By radically copolymerizing phthalate or the like, it becomes possible to introduce a carbon-carbon double bond into the vinyl resin for the hydrosilylation reaction.

The above-mentioned carboxylic acid or acid anhydride is
The vinyl resin obtained has an acid value of 20 to 150 mgKOH / g, preferably 5 in the constituent monomers of the copolymer.
It is necessary to contain it so as to be 0 to 120 mgKOH / g. If the acid value is smaller than the above range, the storage stability of the resulting aqueous dispersion will be poor, and conversely, if it is large, the water resistance and hot water resistance of the resulting coating film will be poor, so both are not preferred. In addition, as the other production method of the above-mentioned silyl group-containing vinyl-based resin, a vinyl-based monomer containing the above-mentioned carboxylic acid or acid anhydride, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryl Roxypropyltriethoxysilane, β- (meth) acryloxyethyltrimethoxysilane, β- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropyl Methyldiethoxysilane, γ
Silyl such as-(meth) acryloxypropylmethyldipropoxysilane, γ- (meth) acryloxybutylphenyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, γ- (meth) acryloxypropyldiethylmethoxysilane There is also a method of containing a group-containing vinyl compound as an essential monomer and radically polymerizing one or more of the above-mentioned other vinyl-based monomers. Specific examples of these silyl group-containing vinyl resins include Kaneka Zemurask manufactured by Kanebuchi Chemical Co., Ltd. as a commercially available product.

Next, a method for producing the organic-inorganic composite resin aqueous dispersion which is the component (i) will be described. First, the mixture of the component (a) and the component (b) is subjected to hydrolysis and condensation reaction in the presence of water and a catalyst, for example. (A)
The mixing ratio of the component and the component (b) is 5 to 200 parts by mass, preferably 10 to 1 for the former 100 parts by mass.
Suitably 50 parts by weight. Incidentally, if the latter is less than the above range, the appearance of the obtained coating film, crack resistance, frost damage resistance, alkali resistance, etc. deteriorate, and conversely, if too much, weather resistance of the obtained coating film, and It is not preferable because the stain resistance is deteriorated. The amount of water was 4 times the hydrolyzable group initially present in the mixture of component (a) and component (b).
5 to 100%, preferably 50 to 90% is an amount sufficient for the hydrolysis and condensation reaction, and specifically 0.4 to 1.0 times the total number of hydrolyzable groups in the mixture. The amount is preferably 0.5 to 0.9 times the number of moles.

Examples of the catalyst include inorganic acids such as nitric acid and hydrochloric acid, and organic acids such as acetic acid, formic acid and propionic acid. The amount of catalyst added is such that the pH of the mixture is 3
An amount of ~ 6 is suitable. The hydrolysis condensation reaction is
The mixture of the component (a) and the component (b) is, for example, in the presence of water and a catalyst, 40 to 80 ° C, preferably 45 to 6 ° C.
A method of reacting while stirring at 5 ° C. for 2 to 10 hours is suitable, but not limited to this method. It is to be noted that the content of the hydrolyzable group initially present in the mixture of the components (a) and (b) is 45% or more when the organic-inorganic composite resin aqueous dispersion (emulsion) is formed. This is because it has good storage stability and can form a highly transparent film when used in a paint. It is possible to carry out the hydrolysis-condensation reaction of the components (a) and (b) in one step as described above, but from the viewpoint of storage stability of the product, the reaction is carried out in the following two steps. Preferably. That is, as the first step, in the presence of water and an acid catalyst, (a)
40-80%, preferably 45-70%, of the hydrolyzable groups initially present in the mixture of component and component (b).
Is hydrolyzed and condensed, the reaction is carried out at 40 to 80 ° C., preferably 45 to 65 ° C. for 1 to 8 hours with stirring.

As the second step, following the first step, water and trialkoxyborane such as trimethoxyborane and triethoxyborane; tri-n-butoxyethylacetoacetate zirconium, di-n-butoxydi (ethylacetoacetate Acetate) zirconium, tetrakis (ethylacetoacetate) zirconium and other zirconium chelate compounds, diisopropoxybis (acetylacetate) titanium, diisopropoxybis (ethylacetoacetate) titanium and other titanium chelate compounds, monoacetylacetate bis (ethylacetate) Acetate) Aluminum, an organometallic compound catalyst such as an aluminum chelate compound such as aluminum diisopropoxyethylacetoacetate is added, and a hydrolysis and condensation reaction is performed.
The amount of water added in the second stage was 45% of the hydrolyzable group initially present in the mixture of the components (a) and (b).
-100%, preferably 50-90% is sufficient for the hydrolysis and condensation reactions.

The trialkoxyborane and the organometallic compound catalyst used in the second step can accelerate the condensation reaction and improve the appearance of the coating film, weather resistance, stain resistance, hot water resistance and the like. The amount of these catalysts is 0.001 to 5 parts by mass based on 100 parts by mass of the total amount of the above-mentioned components (a) and (b) remaining unreacted with the reaction product obtained in the first step, Preferably, 0.005 to 2 parts by mass is suitable.
The hydrolysis-condensation reaction in the second step is suitably carried out at 40 to 80 ° C. for 2 to 5 hours, as in the first step. The hydrolysis-condensation reaction product is in a solution state due to the alcohol content produced in the reaction, or due to the alcohol content and an organic solvent which will be described later added as necessary.

A neutralizing agent is added to the solution of the organic-inorganic composite resin which is the reaction product thus obtained, and the mixture is uniformly dispersed.
After neutralization, water is added, or a neutralizing agent and water are added at the same time, and the mixture is forcibly dispersed by stirring to obtain an aqueous dispersion (emulsion). The amount of the neutralizing agent is 50 to 100%, preferably 70 to 10% of the acid groups in the organic-inorganic composite resin as a reaction product so that a stable emulsion can be obtained.
An amount that neutralizes 0% is suitable. Typical examples of the neutralizing agent include triethylamine, triethanolamine, dimethylethanolamine, monoethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, and morpholine. The amount of water is arbitrarily determined in consideration of the coating workability of the paint, but usually the solid content of the coating composition is, for example, 10
An amount of about 70% by mass is suitable.

In the organic-inorganic composite resin aqueous dispersion thus obtained, an alcohol content is produced by the above-mentioned hydrolysis condensation reaction, and this remains in the aqueous dispersion. Therefore, if the aqueous dispersion is used as it is as a coating composition, the amount of volatile organic components (VOC) increases, and therefore the alcohol content may be removed under reduced pressure according to a conventional method.

Component (II) Component (II) is colloidal silica in which silica particles are dispersed in water or an organic solvent. Colloidal silica is
Usually, the average particle size is 5 to 100 nm, preferably 10
A type in which approximately spherical silica particles having a particle size of up to 30 nm are dispersed, and a silica particle having a thickness of 5 to 50 nm and a length of 40 to 40
There is a type in which they are aggregated and dispersed in a chain form of about 0 nm, and any of them can be used. In particular, in the present invention, the chain colloidal silica type has good miscibility stability,
Also, the curability is good, and the hardness of the formed coating film is high,
It is preferable because it has good stain resistance and durability.

Colloidal silica in which substantially spherical silica particles are dispersed in water can be easily obtained as a commercial product, and specific examples thereof include Snowtex ST-manufactured by Nissan Chemical Industries, Ltd. 20, ST-O, S
TC, ST-S, Adelite AT-20, AT-20N, AT-20A, AT-30 manufactured by Asahi Denka Kogyo Co., Ltd.
0 etc. are mentioned. In addition, colloidal silica in which substantially spherical silica particles are dispersed in an organic solvent includes, for example, methanol, ethanol, isopropanol, n-butanol,
Lower fatty acid alcohols such as isobutanol; ethylene glycol, ethylene glycol monobutyl ether,
Ethylene glycol derivatives such as ethylene glycol monoethyl ether acetate; Diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; ketones such as acetone and methyl ethyl ketone; silica particles in organic solvents such as toluene, xylene, ethyl acetate and butyl acetate. This organic solvent-dispersed colloidal silica can also be easily obtained as a commercial product, and specific examples include Snowtex MA-ST manufactured by Nissan Chemical Industries, Ltd.
-M, IPA-ST, EG-ST, EG-ST-ZL and the like.

The chain colloidal silica in which the silica particles are aggregated in a chain form is also dispersed in water or the above-mentioned organic solvent and can be easily obtained as a commercial product. Specific examples include Nissan Chemical Co., Ltd. Snowtex ST-UP, ST-OUP, PS-M, PS-L manufactured by Kogyo Co., Ltd.
(Above, water dispersion system), MA-ST-UP, IPA-ST
-UP (above, solvent dispersion system) etc. are mentioned. The component (II) is blended in order to improve the curability and stain resistance of the coating film, and the blending amount thereof is the solid content based on 100 parts by mass of the solid content of the aqueous dispersion (i). In terms of conversion, for example,
0.1 to 50 parts by mass, preferably 1 to 30 parts by mass is suitable. If the compounding amount of the component (II) is less than the above range, the effect of improving the curability and stain resistance of the coating film is small, and conversely if it is too large, the mixing stability, crack resistance of the coating film, etc. Tends to decrease. The component (II) is mixed with and dispersed in the aqueous dispersion (i) to form a coating, but the component (II) is also effective as a catalyst for the condensation reaction between the components (a) and (b). It is also possible to pre-mix a part or all of the aqueous dispersion (i) at the time of production.

The coating composition of the present invention comprises the above-described aqueous dispersion of component (i) and colloidal silica of component (II), and, if necessary, the storage stability and coating of the coating composition. Water for improving workability, organic solvents and fillers, dyes, curing agents, further curing accelerators, thickeners,
It is composed of a mixture of various additives such as a pigment dispersant. As the organic solvent, methanol, alcohols such as ethanol, propanol, butanol,
Alcohol ethers such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether,
Hydrophilic organic solvents such as ketones such as acetone and methyl ethyl ketone, and toluene, xylene, ethyl acetate,
A mixed organic solvent with various hydrophobic coating organic solvents such as butyl acetate can be used. These organic solvents can be blended as a solvent so that the reaction can occur uniformly during the production of the above-mentioned aqueous dispersion (i). The content of the organic solvent in the coating composition is 0 to 20% by mass, preferably 0 to 10% by mass.

Examples of the filler include talc and
Various extender pigments for paints such as barium carbonate, calcium carbonate, barium carbonate, bentonite, titanium oxide, carbon black, red iron oxide, lithopone, and coloring pigments can be used. The content of the filler is 0 in the solid content of the coating composition.
〜70 mass%, preferably 0 to 50 mass% is suitable. Examples of the curing agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, and N- (β-aminoethyl). −
γ-aminopropylmethyldimethoxysilane, N- (β
-Aminoethyl) -γ-aminopropylmethyldiethoxysilane, N-cyclohexyl γ-aminopropyltrimethoxysilane, N-cyclohexyl-γ-aminopropyltriethoxysilane, γ- (2-aminoethyl)
-Aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane,
Having an amino group in the molecule such as γ-anilinopropyltrimethoxysilane, alkoxysilane capable of hydrolysis and condensation reaction, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, γ-
Glycidoxypropyltriisopropenyloxysilane, γ-glycidoxypropyltriiminooxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, γ-isonanoatepropyltriisopropenyloxysilane Examples thereof include alkoxysilanes having an epoxy group such as an adduct with glycidol and capable of undergoing a hydrolytic condensation reaction.

Examples of the curing accelerator include tin octylate, organic tin compounds such as dibutyltin dilaurate, dibutyltin dimaleate and tributyltin laurate, amine compounds such as ethylenediamine, diethylenetriamine, piperidine, phenylenediamine and triethylamine. As a representative one,
Organic tin compounds are particularly effective. The coating composition of the present invention is applied to the surface of an object to be coated with a brush, spray, roll, dipping or other coating means, and is baked at room temperature or at a temperature of 300 ° C. or lower to form a cured coating film. It is possible. As the article to be coated, it is possible to use, for example, inorganic ceramic substrates, various metal substrates such as stainless steel and aluminum, glass substrates, plastic substrates, paper substrates and other various substrates.

[0026]

EXAMPLES The present invention will now be described in more detail with reference to examples. In the examples, "parts" and "%" are based on mass unless otherwise specified.

Reference Example 1 <Silyl group-containing vinyl resin solution
Preparation of (ii)> 100 parts of ethylene glycol monobutyl ether was added to a reactor equipped with a reflux condenser and a stirrer, and heated to 100 ° C while stirring. Next, 50 parts of isobutyl methacrylate and 31.5 parts of 2-ethylhexyl methacrylate.
Part, γ-methacryloxypropyltrimethoxysilane 1
0 parts, 8.5 parts acrylic acid and t-butylperoxy-2
100 parts of a mixed solution of 2.5 parts of ethyl hexanoate
Dropwise over 3 hours at ℃, then heated to 105 ℃, 2
The time was maintained and the reaction was terminated. The resulting silyl group-containing vinyl resin solution (a) had a solid content concentration of 50%, an acid value of the resin of 65 mgKOH / g, and a number average molecular weight of 10,000.

Reference Example 2 <Silyl group-containing vinyl resin solution
Preparation of (b)> 100 parts of ethylene glycol monobutyl ether was added to a reactor equipped with a reflux condenser and a stirrer, and heated to 100 ° C while stirring. Next, 50 parts of isobutyl methacrylate and 31.5 parts of 2-ethylhexyl methacrylate.
Solution, 8.5 parts of γ-methacryloxypropyltrimethoxysilane, 10.5 parts of acrylic acid and 2.5 parts of t-butylperoxy-2-ethylhexanoate,
The mixture was added dropwise at 100 ° C over 3 hours, then heated to 105 ° C and maintained for 2 hours to complete the reaction. The resulting silyl group-containing vinyl resin solution (b) has a solid content concentration of 50%.
The acid value of the resin was 80 mgKOH / g, and the number average molecular weight was 10,000.

Example 1 (a) Partial hydrolysis-condensation product of methyltrimethoxysilane (SR2402 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%) was placed in a reactor equipped with a reflux condenser and a stirrer.
23 parts, methyltrimethoxysilane 8 parts, dimethyldimethoxysilane 1.7 parts, (b) silyl group-containing vinyl resin solution (ii) 25 parts, isopropanol 10 parts,
After mixing, 3.0 parts of ion-exchanged water and 1N hydrochloric acid 0.1.
05 parts was added and the reaction was carried out at 60 ° C. for 3 hours. Next, 0.5 part of triethoxyborane and 0.5 part of ion-exchanged water were added, and the mixture was further reacted at 60 ° C. for 3 hours. Then, 0.6 parts of triethylamine and 41 parts of water were added and stirred, and further 3.0 parts of water-dispersed colloidal silica (Adelite AT-20 manufactured by Asahi Denka Co., Ltd .; solid content 20%) was added, The mixture was stirred at 50 ° C for 1 hour. Then depressurize (1.3 x
After removing the solvent under 10 ⁴ Pa (100 torr),
Aqueous coating composition A was obtained by adjusting the dilution with water to a solid concentration of 35%.

Example 2 In a reactor equipped with a reflux condenser and a stirrer, (a) 30 parts of methyltrimethoxysilane, 10 parts of dimethyldimethoxysilane, (b) silyl group-containing vinyl resin solution (b) 1
After 6 parts and 5 parts of isopropanol were added and mixed, 5.2 parts of ion-exchanged water and 0.05 part of 1N hydrochloric acid were added,
The reaction was carried out at 60 ° C for 3 hours. Then, add 0.3 parts of monoacetylacetonate bis (ethylacetoacetate) aluminum and 1.5 parts of ion-exchanged water, and further add 60 ° C.
And reacted for 3 hours. Next, 0.8 parts of N, N-dimethylethanolamine and 52 parts of water are added and stirred, and further, organic solvent-dispersed colloidal silica (Snowtex EG-ST manufactured by Nissan Chemical Industries, Ltd .; solid content 20%). )
7.0 parts was added and stirred at 50 ° C. for 1 hour. Next, the solvent was removed under reduced pressure (1.3 × 10 ⁴ Pa (100 torr)), and then diluted with water so that the solid content concentration was 35% to obtain an aqueous coating composition B.

Example 3 In a reactor equipped with a reflux condenser and a stirrer, (a) 23 parts of partially hydrolyzed condensate of methyltrimethoxysilane (SR2402 manufactured by Toray Dow Corning Co., Ltd.) and methyltrimethoxysilane were added. 8 parts, dimethyldimethoxysilane 1.
7 parts, (b) silyl group-containing vinyl resin solution (a) 25
Parts and 10 parts isopropanol were added and mixed, then 3.0 parts ion-exchanged water and 0.05 parts 1N hydrochloric acid were added,
The reaction was carried out at 60 ° C for 3 hours. Then, 0.5 part of triethoxyborane and 0.5 part of deionized water are added, and the mixture is further added to 60 parts.
The reaction was carried out at 0 ° C for 3 hours. Then triethylamine 0.
6 parts and 39 parts of water are added and stirred, and further 5.0 parts of chain-shaped water-dispersed colloidal silica (Snowtex PS-M manufactured by Nissan Chemical Industries, Ltd .; solid content 20%) is added, and the temperature is 50 ° C.
It was stirred for 1 hour. Next, decompression (1.3 × 10 ⁴ Pa
(100 torr)), the solvent was removed, and then the dilution was adjusted with water to a solid content concentration of 35% to obtain an aqueous coating composition C.

Example 4 In a reactor equipped with a reflux condenser and a stirrer, (a) 30 parts of methyltrimethoxysilane, 10 parts of dimethyldimethoxysilane, (b) silyl group-containing vinyl resin solution (b) 1
After 6 parts and 5 parts of isopropanol were added and mixed, 5.2 parts of ion-exchanged water and 0.05 part of 1N hydrochloric acid were added,
The reaction was carried out at 60 ° C for 3 hours. Then, add 0.3 parts of monoacetylacetonate bis (ethylacetoacetate) aluminum and 1.5 parts of ion-exchanged water, and further add 60 ° C.
And reacted for 3 hours. Next, 0.8 part of N, N-dimethylethanolamine and 55 parts of water are added and stirred, and further chain-like water-dispersed colloidal silica (Snowtex ST-UP manufactured by Nissan Chemical Industries, Ltd .; solid content 20). %)
12.0 parts was added and stirred at 50 ° C. for 1 hour. Then
The solvent was removed under reduced pressure (1.3 × 10 ⁴ Pa (100 torr)), and then diluted with water to a solid concentration of 35% to obtain an aqueous coating composition D.

Comparative Example 1 An aqueous coating composition E having a solid content of 35% was obtained in the same manner as in Example 1 except that colloidal silica was not added.

Comparative Example 2 An aqueous coating composition F having a solid content concentration of 35% was obtained in the same manner as in Example 2 except that colloidal silica was not added. A storage stability test was conducted on each of the aqueous coating compositions obtained in Examples 1 to 4 and Comparative Examples 1 and 2. Also,
Add a curing agent to each water-based coating composition immediately before coating and prepare a coated plate as described below, and perform coating film appearance, hardness, stain resistance, hot water resistance, weather resistance, and alkali resistance coating performance tests. The results are shown in the lower part of Table 1.

<Film coating performance test> A gypsum slag perlite plate (thickness: 12 mm) was used as a material, and a polyisocyanate prepolymer solution sealer "V Seran # 1" was used on the surface thereof.
00 sealer "(trade name of Dainippon Paint Co., Ltd.) (100% diluted with a solution of butyl acetate: xylene = 1: 1) is spray-coated so that the applied amount is 90 to 100 g / m ² (wet mass). did. This was dried at 100 ° C. for 5 minutes. Then, as a base paint, an acrylic silicone resin-based paint "V-Celan # 500 Enamel" (trade name, manufactured by Dainippon Paint Co., Ltd.) (butyl acetate: xylene = 1: 1 solution)
0% dilution) was applied by spraying so that the applied amount was 80 to 90 g / m ² (wet mass). 15 at 120 ℃
Dry for minutes. Next, a coating material having the composition shown in Table 1 was spray-coated so that the applied amount was (130 ± 10) g / m ² (wet mass). The coating film was dried by two methods. That is, a coated plate I which was dried at 80 ° C. for 10 minutes and further dried at room temperature for 3 days and a coated plate II which was dried at 50 ° C. for 5 minutes and further dried at room temperature for 3 days were prepared.
The test method and evaluation were performed based on the following.

Storage stability : Each aqueous coating composition was stored at 50 ° C. for 1 month, and then the change in viscosity and the appearance were visually evaluated. ◯: No change Δ: Thickening ×: Gelation, precipitate generation Appearance : The appearance of the coating film formed on the coated plate was visually determined. ○: No particular abnormality ×: Abnormality Hardness : Pencil hardness measured by JIS K 5400 Contamination resistance : Wet with n-butanol one day and one month after applying the red and black magic inks. The cloth was wiped with a cloth and the decontamination property was visually evaluated. ◎ ・ ・ ・ Complete removal ○ ・ ・ ・ Extremely slight pollution △ ・ ・ ・ Slight contamination × ・ ・ ・ Remarkable contamination

Hot water resistance : After the coated plate was immersed in water at 80 ° C. for 6 hours, the appearance of the coating film was visually judged. ○: No change △: Minor change such as decrease in gloss and whitening ×: Significant change such as decrease in gloss and whitening Weather resistance : Sunshine Weather-Ometer 3000
Time: No change in coating appearance, gloss retention rate 95% or more △: slight change in coating appearance, gloss retention rate 80-
94% × ... Remarkable change in coating film, gloss retention rate less than 80% Alkali resistance : 40% coated plate in saturated slaked lime alkali aqueous solution
After soaking at 10 ° C. for 10 days, the coating film surface was visually evaluated. ○ ・ ・ ・ No change △ ・ ・ ・ Slight turbidity on film surface × ・ ・ ・ Sky turbidity on coating film surface

[0038]

[Table 1] Table 1

As is clear from Table 1, Example 1 of the present invention
~ 4 had excellent coating film performance. On the other hand, in Comparative Examples 1 and 2 which are coating compositions containing no colloidal silica, the coating film hardness was low, and the stain resistance, hot water resistance, weather resistance, alkali resistance, etc. were poor.

The coating composition of the present invention has good curability and can form a coating film excellent in stain resistance, hot water resistance, weather resistance, solvent resistance, alkali resistance and the like.

Continued front page    (72) Inventor Hiroharu Sasaki             7-1414 Shimonagata, Nishinasuno Town, Nasu District, Tochigi Prefecture             46 (72) Inventor Hiroaki Omoto             8-15 Asahi-cho, Nishinasuno-cho, Nasu-gun, Tochigi Prefecture             Ji heim 105 F term (reference) 4J038 CL001 DL031 DL111 HA446                       KA06 MA08 MA10 NA03 NA04                       NA05

Claims (3)

[Claims] (I) (a) Formula (1), R ¹ _n Si (OR ² ) _4-n [wherein, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] 100 parts by mass of organosilane and / or its partial hydrolyzed condensate, and (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20 to 150 mgKOH / G of silyl group-containing vinyl resin 5 to 200 parts by mass, a water-dispersion liquid obtained by neutralizing a hydrolysis condensation reaction product with a neutralizing agent and adding water, and (II) colloidal silica An aqueous coating composition comprising: 2. The aqueous coating composition according to claim 1, wherein the colloidal silica (II) is a chain colloidal silica. 3. Colloidal silica (II) in terms of solid content of 100 parts by mass of solid content of the aqueous dispersion (i) is calculated as solid content.
The aqueous coating composition according to claim 1 or 2, containing 1 to 50 parts by mass.