JP3435599B2 - Hydrophilic curable composition for architectural exterior and method for imparting hydrophilicity to architectural exterior surface - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a curable resin for building exteriors.
Composition (hereinafter referred to as "hydrophilic curable composition for building exterior")
Or ( also referred to as "hydrophilic curable composition") (curable composition for top coating used for building exterior) and a method for imparting hydrophilicity to the surface of building exterior.

[0002]

2. Description of the Related Art Conventionally, the surface of industrial products such as ceramic materials, steel, and construction and building materials has been coated with a composition containing an acrylic silicone resin.
With this, a high-hardness film is formed on the surface, not to mention that the industrial product can be provided with a design effect, thereby improving physical properties such as weather resistance and corrosion resistance of the industrial product. It was

Further, today, there is a social demand for imparting hydrophilicity to the film surface for the following reasons. That is, for example, pollution of buildings has become a problem mainly in urban areas. However, by improving the wettability of the surface, contaminants adhering to the surface can be washed away by rainwater or the like, and the stain resistance of the building can be improved.

Although the hydrophilicity can be imparted by the method of adding a surfactant to the above composition, there are problems in that the surface hardness is lowered and the hydrophilicity is maintained even when exposed to the outdoors for a long time, which is still satisfactory. It wasn't the way.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a hydrophilic curable composition having excellent surface hardness and capable of retaining hydrophilicity even when exposed outdoors for a long period of time. To provide a method for imparting hydrophilicity to the building exterior surface by using the hydrophilic curable composition in order to facilitate washing away of contaminants attached to the building exterior surface by rainwater etc. Where it is.

[0006]

The hydrophilic curable composition for building exterior of the present invention comprises (A) a general formula;

[Chemical 2] (In the formula, R ₁ is an alkyl group having 1 to 10 carbon atoms, R ₂ is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group, a represents 0, 1 or 2) and 100 parts by weight of an alkoxysilyl group-containing acrylic copolymer containing 20 to 50 parts of n-butyl methacrylate as a copolymerization monomer, (hereinafter, Simply referred to as "part"), (B) tetraalkyl silicate and / or its condensate 5 to 60 parts, and (C) curing catalyst.

Further, hydrophilizing method for building exterior surface of the present invention, the parent aqueous imparted to the building exterior surface, thereby, the contaminants adhering to exterior building surface to a method of easily washed away by rain water or the like The method is characterized in that the above-mentioned hydrophilic curable composition for building exterior is applied to the surface of building exterior.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The alkoxysilyl group-containing acrylic copolymer of component (A), which is one component in the composition of the present invention (hereinafter referred to as "alkoxysilyl group-containing acrylic copolymer (A)" or simply " (Also referred to as "(A) ingredient")
Is a general formula;

[Chemical 3] It is a polymer having at least one, preferably two or more alkoxysilyl groups in each molecule. The alkoxysilyl group may be contained at the end of the main chain of the component (A), may be contained in the side chain, or may be contained in both.

When the number of alkoxysilyl groups in one molecule of the component (A) is less than 1, the solvent resistance of the cured product (for example, coating film) obtained from the composition of the present invention tends to decrease.

In the above formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms. When the carbon number is more than 10, the reactivity of the alkoxysilyl group is lowered, and the reactivity is lowered even when R ¹ is other than an alkyl group, for example, a phenyl group or a benzyl group.

Specific examples of R ¹ include, for example, a methyl group,
Examples thereof include ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group.

In the above formula, R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 4 alkyl groups, aryl groups and aralkyl groups. .

Specific examples of the alkyl group represented by R ² include:
Mentioned the same groups as R ^1, specific examples of the aryl group, for example, a phenyl group and the like, specific examples of the aralkyl group include benzyl group.

Specific examples of the alkoxysilyl group represented by the general formula [Chemical Formula 3] include groups contained in the alkoxysilyl group-containing monomer described later.

The alkoxysilyl group-containing acrylic copolymer (A) is excellent in weather resistance, chemical resistance, water resistance, etc. of the cured product because its main chain is substantially composed of the acrylic copolymer chain. Furthermore, in the component (A), if the alkoxysilyl group is bonded to a carbon atom, the resulting cured product will have even more excellent water resistance, alkali resistance, acid resistance and the like.

The number average molecular weight of the alkoxysilyl group-containing acrylic copolymer (A) is 1,000 to 30, from the viewpoint of physical properties such as durability of the cured product obtained from the composition of the present invention.
000 is preferable, and 3,000 to 25,000 is more preferable.

The component (A) is an acrylic monomer such as acrylic acid, methacrylic acid or a derivative thereof, and
It can be obtained by copolymerization with an alkoxysilyl group-containing monomer.

The acrylic monomer is not particularly limited,
Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, Trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (meth) acrylonitrile,
Glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethylacrylamide, N-methyl acrylamide, acryloyl morpholine, 2-hydroxyethyl (meth) acrylate, 2-
Hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, Toagosei Chemical Industry Co., Ltd.
Aronix M-5700 manufactured by Toa Gosei Chemical Industry Co., Ltd.
Manufactured macromonomers AS-6, AN-6, AA-
6, AB-6, AK-5, Placcel FA-1, Placcel FA- manufactured by Daicel Chemical Industries, Ltd.
4, Placcel FM-1, Placcel FM
-4, a phosphoric acid ester group-containing vinyl which is a condensation product of a hydroxyalkyl ester of α, β-ethylenically unsaturated carboxylic acid such as hydroxyalkyl ester of (meth) acrylic acid and phosphoric acid or phosphoric acid ester Examples thereof include system compounds, (meth) acrylates containing urethane bonds and siloxane bonds.

The alkoxysilyl group-containing monomer is not particularly limited except that it has a polymerizable double bond, and specific examples thereof include, for example,

[Chemical 4]

[Chemical 5] And the like, and also includes (meth) acrylate having an alkoxysilyl group at the terminal via a urethane bond or a siloxane bond.

The proportion of the alkoxysilyl group-containing monomer in the component (A) is preferably 5 to 90%, more preferably 10 to 70% from the viewpoint of the curability of the composition and the durability of the coating film.

The component (A) may contain a segment formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50%, and is derived from a monomer other than the (meth) acrylic acid derivative. The segment may be included. The monomer is not limited, and specific examples thereof include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, vinyltoluene; maleic acid, fumaric acid. Acids, unsaturated carboxylic acids such as itaconic acid, their salts (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.), or those and C1-C20 direct Esters of unsaturated carboxylic acids such as diesters or half esters with chain or branched alcohols; vinyl acetate,
Vinyl propionate, vinyl esters and allyl compounds such as diallyl phthalate; Vinyl group-containing vinyl compounds such as vinyl pyridine and aminoethyl vinyl ether;
Amide group-containing vinyl compounds such as itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone; 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, Other vinyl compounds such as butadiene, isoprene, fluoroolefin maleimide, N-vinyl imidazole, vinyl sulfonic acid and the like can be mentioned.

The alkoxysilyl group-containing acrylic copolymer (A) can be produced, for example, by the method described in JP-A-54-36395, JP-A-57-36109, JP-A-58-157810 and the like. However, it is most preferable to manufacture by a solution polymerization method using an azo radical initiator such as azobisisobutyronitrile from the viewpoint of ease of synthesis.

Also in this case, if necessary, n-dodecylmercaptan, t-dodecylmercaptan, n-butylmercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane. ,
γ-mercaptopropylmethyldiethoxysilane, (C
_{H 3 O) 3 Si-S} -S-Si (OCH 3) 3, using a chain transfer agent such as, can be adjusted molecular weight. In particular, a chain transfer agent having an alkoxysilyl group in the molecule,
For example, it is preferable to use γ-mercaptopropyltrimethoxysilane because the alkoxysilyl group can be introduced into the terminal of the silyl group-containing acrylic copolymer.

The polymerization solvent used in the solution polymerization method includes hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetic acid esters (ethyl acetate, butyl acetate, etc.), ethers (ethyl cellosolve, Butyl cellosolve, cellosolve acetate, etc.),
There is no particular limitation as long as it is a non-reactive solvent such as ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, acetone, etc.).

The alkoxysilyl group-containing polymer (A) may be used alone or in combination of two or more kinds.

From the viewpoint of compatibility with the tetraalkyl silicate of component (B) and / or its condensate,
It is desirable to introduce 20 to 50 parts of n-butyl methacrylate as a copolymerizable monomer in the component (A).

The component (B) tetraalkyl silicate and / or its condensate used in the present invention improves the hydrophilicity and hardness of the cured coating film obtained by coating the composition, or the coating film and the base material. Improves the adhesion of materials.

Examples of the tetraalkyl silicate include tetramethyl silicate, tetraethyl silicate, tetra-n-propyl silicate, tetra-i-propyl silicate, tetra-n-butyl silicate and the like.

The condensate of tetraalkyl silicate can be produced by a known production method in which it is obtained by condensing the above tetraalkyl silicate under hydrolysis conditions. That is, it can be carried out by adding water to the tetraalkyl silicate to cause condensation. Moreover, a commercial item can also be used for the tetraalkyl silicate condensate. As such a condensate, for example,
Examples include MSI51, ESI28, ESI40 (all manufactured by Colcoat Co., Ltd.).

The above tetraalkyl silicate and / or its condensate may be mixed with the component (A),
When the component (A) is synthesized, that is, when the alkoxysilyl group-containing monomer and the acrylic monomer are copolymerized, the component (B) can be allowed to be present in the reaction vessel in advance. The latter method improves compatibility and hydrophilicity.

The compounding ratio of the above tetraalkyl silicate is 2 to 60 parts, preferably 5 to 40 parts per 100 parts of the resin component (A). If it is less than 2 parts, the resulting cured product is not sufficiently hydrophilic, and if it exceeds 60 parts, the appearance of the cured product is deteriorated and cracks are likely to occur.

Specific examples of the curing catalyst (hereinafter referred to as "curing catalyst (C)" or simply "(C) component") which is the component (C) used in the present invention include dibutyltin dilaurate, dibutyltin malate and dioctyl. Organotin compounds such as tin laurate, dioctyl tin malate and tin octylate, phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl Phosphates such as phosphate and didecyl phosphate; propylene oxide,
Butylene oxide, cyclohexene oxide, glycidyl methacrylate, glycidol, acryl glycidyl ether, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane,

[Chemical 6] Yuka Shell Epoxy Co., Ltd. Cardura E, Yuka Shell Epoxy Co., Ltd. Epicoat 828, Epicoat 1
Addition reaction products of epoxy compounds such as 001 with phosphoric acid and / or monoacidic phosphoric acid ester, maleic acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, succinic acid, phthalic acid, trimellitic acid, Examples of the acid compound include pyromellitic acid, acid anhydrides thereof, paratoluenesulfonic acid, and dodecylbenzenesulfonic acid. Also included are mixtures or reactants of these acidic catalysts and amines. For example, hexylamine,
Examples of amines include N, N-dimethyldodecylamine and dodecylamine.

Among these curing catalysts (C), acidic curing catalysts are desirable, and particularly acidic phosphoric acid esters, mixtures or reaction products of acidic phosphoric acid esters and amines have high activity, and hydrophilicity is also preferable. The curing catalyst (C) may be used alone or in combination of two or more kinds.

The amount of the component (C) used is not particularly limited, but is usually 0.1 to 20 parts, preferably 0.1 to 20 parts, relative to 100 parts of the resin solid content of the components (A) and (B). ~ 1
0 part is more preferable. When the amount of the component (C) used is less than 0.1 part, the curability tends to decrease, and when it exceeds 20 parts, the appearance of the coating film tends to decrease.

It is preferable to use a dehydrating agent and an alkyl alcohol in order to ensure storage stability that does not cause a problem even after repeated use over a long period of time.

Specific examples of the dehydrating agent include methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, methyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, and methylsilicate. Hydrolyzable ester compounds such as ethyl silicate may be mentioned. Examples of the alkyl alcohol include low molecular weight alcohols such as methanol and ethanol. The dehydrating agent and the alkyl alcohol may be added before the polymerization of the alkoxysilyl group-containing polymer (A), after the polymerization, or during the polymerization.

The amounts of the dehydrating agent and the alkyl alcohol are not particularly limited, but 0.5 to 20 parts and 2 to 10 parts are more preferable for 100 parts of the resin solid content of the components (A) and (B). .

When a dehydrating agent and an alkyl alcohol are used in combination, a remarkable effect on storage stability can be seen.

In the composition of the present invention, additives such as a diluent, a pigment (including an extender pigment), an ultraviolet absorber, a light stabilizer, an antisettling agent, a leveling agent, etc., depending on the application; nitrocellulose, cellulose acetate. A fibrin such as butyrate; a resin such as an epoxy resin, a melamine resin, a vinyl chloride resin, a chlorinated polypropylene, a chlorinated rubber, polyvinyl butyral; and a filler may be added.

After the above composition is applied to an article to be coated by a conventional method such as various coatings, especially dipping, spraying, brushing, etc., the composition is usually cured at 30 ° C. or higher to give good adhesion to the surface of the article to be coated. It is possible to form a coating film having excellent durability.

[0041]

EXAMPLES Hereinafter, the hydrophilic curable composition for building exterior of the present invention will be described more specifically based on examples.

Synthesis Example 1 40.4 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing tube and a dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, the mixture (a) having the following composition was added dropwise at a constant rate over 5 hours by a dropping funnel. Mixture (a) Methyl methacrylate 28.4 parts N-butyl methacrylate 47.1 parts Butyl acrylate 11.8 parts γ-methacryloxypropyltrimethoxysilane 11.8 parts Acrylamide 0.9 parts Xylene 17.9 parts 2, 2-Azobisisobutyronitrile 1.0 part.

After the addition of the mixture (a) was completed, 0.5 parts of 2,2-azobisisobutyronitrile and 8.1 parts of toluene were added dropwise at a constant rate over 1 hour. After dripping, at 110 ℃ 2
After aging for time, the mixture was cooled and xylene was added to the resin solution to adjust the solid content concentration to 50%. The number average molecular weight of the obtained resin was 15,000.

Synthesis Example 2 40.4 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel, and the temperature was raised to 110 ° C. while introducing nitrogen gas. Then, the mixture (b) having the following composition was added dropwise at a constant rate through the dropping funnel over 5 hours. Mixture (b) Methyl methacrylate 56.6 parts Butyl acrylate 30.7 parts γ-methacryloxypropyltrimethoxysilane 11.8 parts Acrylamide 0.9 parts Xylene 17.9 parts 2,2-Azobisisobutyronitrile 1.0 part.

After the addition of the mixture (b) was completed, 0.5 parts of 2,2-azobisisobutyronitrile and 8.1 parts of toluene were added dropwise at a constant rate over 1 hour. After dripping, at 110 ℃ 2
After aging for time, the mixture was cooled and xylene was added to the resin solution to adjust the solid content concentration to 50%. The number average molecular weight of the obtained resin was 15,000.

Synthesis Example 3 ESI 40 (*) was added to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel.
And 10.4 parts of xylene were charged, the temperature was raised to 110 ° C. while introducing nitrogen gas, and then the mixture (c) having the following composition was added dropwise at a constant rate over 5 hours by a dropping funnel. (* Commercial product of tetraethyl silicate condensate manufactured by Colcoat Co., Ltd.).

[0047]   Mixture (c)     Methyl methacrylate 56.6 parts     Butyl acrylate 30.7 parts     γ-methacryloxypropyltrimethoxysilane 11.8 parts     Acrylamide 0.9 parts     Xylene 17.9 parts     2,2-azobisisobutyronitrile 1.0 part.

After the addition of the mixture (c) was completed, 0.5 parts of 2,2-azobisisobutyronitrile and 8.1 parts of toluene were added dropwise at a constant rate over 1 hour. After dripping, at 110 ℃ 2
After aging for time, the mixture was cooled and xylene was added to the resin solution to adjust the solid content concentration to 50%. The number average molecular weight of the obtained resin was 15,000.

Example 1 For 100 parts of the resin shown in Synthesis Example 1, M as the component (B) was used.
30 parts of SI51 (manufactured by Colcoat Co., Ltd.) was blended. Using this resin solution, titanium oxide (CR-90 manufactured by Ishihara Sangyo Co., Ltd.) was dispersed to have a PWC (ratio of pigment to total solids) of 40% and a coating solid concentration of 60% to adjust white enamel. . Dispersion was performed for 2 hours with a paint conditioner using glass beads. Dioctyl phosphate and dodecylamine were added to the white enamel as a curing catalyst in an amount of 0.25 parts per 100 parts of the resin solid content, and diluted with thinner to a solid content concentration of 45%.

This paint was applied to an aluminum plate (A5052P) by air spray so that the dry film thickness was about 30 μm. Then, the coated plate was cured at 23 ° C. for 7 days to form a coating film on the surface of the aluminum plate. The glossiness, Peroz hardness, contact angle with water and contact angle with water after exposure for 3 months were measured. The results are shown in [Table 2].

Examples 2 to 6, and Comparative Examples 1 to 1
Example 3 A white enamel was prepared from the compounding composition shown in [Table 1] under the same conditions as above to prepare a coating material. Similarly, the curing catalyst shown in [Table 1] was added, and the mixture was diluted with a thinner to a solid content concentration of 45%.

This paint was applied to an aluminum plate (A5052P) by air spraying so that the dry film thickness was about 30 μm. Thereafter, the coated plate was cured under the curing conditions shown in [Table 1], and the glossiness of the coating film, Peroz hardness, the contact angle with water and the contact angle with water after exposure for 3 months were measured. The results are also shown in [Table 2].

[0053]

[Table 1]

[Table 2]

[0054]

By the hydrophilic curable composition for building exterior and the method for imparting hydrophilicity to the surface of building exterior of the present invention, a coating film having excellent surface hardness and capable of retaining hydrophilicity even when exposed outdoors for a long period of time. Can be formed on a building exterior surface. This makes it easier for the contaminants adhering to the exterior surface of the building to be washed away by rainwater or the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C09D 143/04 C08K 5/541 C08L 43/04

Claims (5)

(57) [Claims] 1. A general formula (A); (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, R ² is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group, a represents 0, 1 or 2) and 100 parts by weight of an alkoxysilyl group-containing acrylic copolymer containing 20 to 50 parts of n-butyl methacrylate as a copolymerization monomer, and (B). A curable composition for building exterior, comprising 5 to 60 parts by weight of a tetraalkyl silicate and / or a condensate thereof, and (C) a curing catalyst. 2. The component (A) is a polymer having an alkoxysilyl group-containing monomer having a polymerizable double bond in the molecule as a copolymerization component, and the alkoxysilyl group in the component (A). The curable composition for building exterior according to claim 1, wherein the content of the contained monomer is 5 to 90% by weight. 3. The curable composition for building exterior according to claim 1, wherein the component (C) is an acidic curing catalyst. 4. The acidic curing catalyst is an acidic phosphoric acid ester, a mixture or reaction product of an acidic phosphoric acid ester and an amine, a saturated or unsaturated polyvalent carboxylic acid, an acid anhydride of a saturated or unsaturated polyvalent carboxylic acid. The curable composition for building exterior according to claim 3. 5. A method for imparting hydrophilicity to a building exterior surface, thereby facilitating washing away of contaminants adhering to the building exterior surface with rainwater or the like, according to any one of claims 1 to 4. A method for imparting hydrophilicity to a building exterior surface, which comprises applying the curable composition for building exterior to the surface of the building exterior.