JP2000212509A5 - - Google Patents

Description

[Claims]
1. A coating film composed of the following (I) undercoating coating composition is formed on a base material, and a coating film composed of the following (II) overcoating coating composition is formed on the coating film. A method for forming a coating film.
(I) (A) (a) A coating composition for an undercoat containing an aqueous dispersion obtained by dispersing a polymer containing a polyorganosiloxane and (b) a vinyl-based polymer in an aqueous medium.
Polymers containing (II) (A) (a) polyorganosiloxane and (b) vinyl-based polymer, and (B) photocatalytic inorganic fine particles and / or sol are dispersed in an aqueous medium. A coating composition for a top coat containing an aqueous dispersion.
[Claim 2] (B) The vinyl-based polymer has a main chain composed of a vinyl-based polymer, and has at least one hydrolyzable silyl group and / or hydroxysilyl group at the end and / or side chain of the polymer molecular chain, and The method for forming a coating film according to claim 1, which is a polymer having at least one hydrophilic functional group (vinyl-based polymer (b1)).
[Claim 3] The method for forming a coating film according to claim 2, wherein the vinyl-based polymer (b1) has a polystyrene-equivalent number average molecular weight of 2,000 to 100,000.
[Claim 4] The method for forming a coating film according to claim 2 or 3, wherein the amount of the vinyl polymer (b1) used is 2 to 900 parts by weight with respect to 100 parts by weight of the polyorganosiloxane (a1).
[Claim 5] The method for forming a coating film according to claims 1 to 4, wherein the composition (I) and the composition (II) contain a chelate compound (organic metal compound (C)) of a metal selected from the group of zirconium, titanium and aluminum. ..
Claim6] Claim 1To any ofA cured product obtained by the method for forming a coating film described.
[Claim 7] The cured product according to claim 6, wherein the cured product is composed of a base material / (I) composition / (II) composition or a base material / primer / (I) composition / (II) composition.
[Claim 8] The cured product according to claim 6 or 7, wherein the total film thickness of the undercoat layer and the topcoat layer is a dry film thickness, usually 0.1 to 80 μm.

0002.
[Conventional technology]
Conventionally, various treatments have been performed on the coating material in order to improve the stain resistance and waterproof property of the coating film surface. However, with the conventional surface treatment method, it is difficult to obtain a coating film having high hardness due to excellent adhesion, weather resistance, heat resistance, moisture resistance, stain resistance, antibacterial property, antifungal property, deodorant function, etc. there were. Especially in the case of outdoor structures, it is recognized that the surface of the coating film should be made hydrophilic in order to improve the stain resistance, and for example, a method of adding a hydrophilic substance or a water-soluble substance has been proposed. However, with such a method, hydrophilic substances and water-soluble substances are gradually deteriorated by light or washed away by water, and it is difficult to maintain the hydrophilicity of the coating film surface to a sufficient level for a long period of time. there were. In addition, the conventional photocatalytic inorganic fine particle dispersion has poor stretchability, so high-temperature firing is required, it is difficult to thicken the film, the adhesion to the substrate is insufficient, and the application is limited, and the long-term durability is very high. There were problems such as scarcity. Further, all the conventional coating materials used for forming a coating film are solvent type, and in recent years, there has been a strong demand for solvent removal from the viewpoints of low pollution, resource saving, safety and hygiene, and the like. The present inventors have been found a photocatalyst dispersion coating material using the aqueous dispersion of silicone over emissions system, photocatalyst dispersion coating material, because of its photocatalytic activity, it degrades the substrate surface, the substrate and the coating There was a problem that the long-term adhesion with the material was inferior.

0004
[Means for solving problems]
In the present invention, a coating film composed of the following (I) undercoating coating composition is formed on a base material, and a coating film composed of the following (II) overcoating coating composition is formed on the coating film. It is a feature.
A polymer containing (I) (A) (a) polyorganosiloxane and (b) vinyl-based polymer (hereinafter, also referred to as “specific polymer (A)”) is dispersed in an aqueous medium. An undercoat coating composition containing an aqueous dispersion (hereinafter, also referred to as “(I) composition”).
(II) The specific polymer (A) and (B) inorganic fine particles having photocatalytic activity and / or sol (hereinafter, also referred to as “photocatalytic component (B)”) are dispersed in an aqueous medium. A coating composition for a top coat containing a body (hereinafter, also referred to as “(II) composition”).
The vinyl-based polymer (b) has a main chain composed of a vinyl-based polymer, and has at least one hydrolyzable silyl group and / or hydroxysilyl group at the terminal and / or side chain of the polymer molecular chain. And a polymer having at least one hydrophilic functional group (vinyl-based polymer (b1)) is preferable.
Further, the polystyrene-equivalent number average molecular weight of the vinyl polymer (b1) is preferably 2,000 to 100,000.
The amount of the vinyl polymer (b1) used is preferably 2 to 900 parts by weight with respect to 100 parts by weight of the polyorganosiloxane (a1).
The present invention also relates to a method for forming a coating film containing a chelate compound (organic metal compound (C)) of a metal selected from the group of zirconium, titanium and aluminum in the composition (I) and the composition (II). ..
The present invention also provides a cured product obtained by the above method for forming a coating film.
The composition of the cured product is preferably a base material / (I) composition / (II) composition or a base material / primer / (I) composition / (II) composition.
The total film thickness of the undercoat layer and the topcoat layer is usually 0.1 to 80 μm in terms of dry film thickness.
Hereinafter, the composition used in the present invention will be specifically described.

The functional unsaturated polymer used in the method (a) above can be produced, for example, as follows. That is, (a-1) a vinyl-based monomer having a hydrophilic functional group is (co) polymerized together with other vinyl-based monomers in some cases to synthesize a precursor (co) polymer, and then the precursor (co) polymer is synthesized. A functional group capable of reacting with a complementary functional group (α) to an appropriate functional group (hereinafter, referred to as “complementary functional group (α)”) in the (co) polymer (hereinafter, “complementary functional group (hereinafter”). By reacting an unsaturated compound having a carbon-carbon double bond with β) ”), a functional unsaturated polymer having a carbon-carbon double bond in the side chain of the polymer molecular chain is produced. be able to. Further, (a-2) a complementary functional group (alpha) a radical polymerization initiator having a (such as 4,4 '- azobis-4-cyanovaleric acid) of using, or radical polymerization initiator and a chain transfer agent compounds having both a complementary functional group (alpha) (such as 4,4 '- azobis-4-cyanovaleric acid and dithioglycolic acid, etc.) using, a vinyl monomer having a hydrophilic functional group, if A precursor (co-) having a complementary functional group (α) derived from a radical polymerization initiator or a chain transfer agent at one end or both ends of the polymer molecular chain by (co) polymerizing with other vinyl-based monomers. ) After synthesizing the polymer, the complementary functional group (α) in the precursor (co) polymer is reacted with an unsaturated compound having a complementary functional group (β) and a carbon-carbon double bond. Therefore, a functional unsaturated polymer having a carbon-carbon double bond at one end or both ends of the polymer molecular chain can be produced. Further, (a-3) A functional unsaturated polymer can also be produced by the combination of (a-1) and (a-2) described above. Examples of the reaction between the complementary functional group (α) and the complementary functional group (β) in the methods (a-1) and (a-2) include an esterification reaction between a carboxyl group and a hydroxyl group and carboxylic acid anhydride. Ring-opening esterification reaction between a physical group and a hydroxyl group, esterification reaction between a carboxyl group and an epoxy group, amidation reaction between a carboxyl group and an amino group, ring-opening amidation reaction between a carboxylic acid anhydride group and an amino group, Examples thereof include a ring-opening addition reaction between an epoxy group and an amino group, and a urethanization reaction between a hydroxyl group and an isocyanate group.

The polystyrene-equivalent number average molecular weight (hereinafter referred to as “Mn”) of the vinyl polymer (b1) obtained as described above is preferably 2,000 to 100,000, more preferably 4,000 to 50,000. Is. In the present invention, the vinyl polymer (b1) or in alone may be used by mixing two or more kinds. The amount of the vinyl polymer (b1) used in the present invention is usually 2 to 900 parts by weight, preferably 10 to 400 parts by weight, more preferably 20 to 200 parts by weight, based on 100 parts by weight of the polyorganosiloxane (a1). It is a part by weight. In this case, if the amount of the vinyl polymer (b1) used is less than 2 parts by weight, the alkali resistance of the coating film formed from the aqueous dispersion tends to decrease, while if it exceeds 900 parts by weight, the coating film of the coating film tends to have low alkali resistance. Weather resistance tends to decrease.

The coating operation in the present invention differs depending on the type and condition of the base material and the coating method. For example, in the case of metallic substrates, if necessary for rust prevention, using primers other than prime coat Coat pos- sesses composition of the present invention, when the inorganic ceramic base material, properties of the substrate (surface roughness, impregnation Since the hiding power of the coating film differs depending on the property, alkalinity, etc.), a primer may be used. In the case of repainting the deteriorated coating film, a primer is used when the deterioration of the old coating film is remarkable. In the case of other base materials such as plastic, wood, paper, glass and the like, a primer may or may not be used in addition to the coating composition for undercoating depending on the application.

The primers, for example, alkyd resins, amino alkyd resins, epoxy resins, polyesters, acrylic resins, urethane resins, fluorocarbon resins, but a solvent may be used resins such as an acrylic silicone over down resin, an acrylic resin emulsion, Water-based emulsions such as epoxy resin emulsions, polyurethane emulsions, and polyester emulsions can be mentioned as particularly preferable. Further, various functional groups can be added to these primers when adhesion between the base material and the coating film is required under severe conditions. Examples of such a functional group include a hydroxyl group, a carboxyl group, a carbonyl group, an amide group, an amine group, a glycidyl group, an alkoxysilyl group, an ether bond, and an ester bond.

In Table 3, the organic ultraviolet absorber (1) shows 2-hydroxyphenylbenzotriazine, and the organic ultraviolet absorber (2) shows 2- (2'-hydroxy-5'-methylphenyl) benzotriazole.

Preparation Example 16 <Preparation of (II) composition>
350 parts of titanium oxide sol (antase-type titanium oxide 20% (solid content), nitrate 80%) was added as a photocatalyst component (B) to a reactor equipped with a stirrer and a reflux cooler, and methyl as an organosilane (a1). While dropping 70 parts of trimethoxysilane and 30 parts of dimethyldimethoxysilane, 50 parts of the vinyl polymer (b-1) obtained in Reference Example 1 and 180 parts of i-propyl alcohol as the vinyl polymer (b). After stirring, 5 parts of di-i-propoxy ethylacetoacetate aluminum was added as the organometallic compound (C), and the mixture was reacted at 60 ° C. for 4 hours. Next, 5 parts of acetylacetone was added as the β-keto compound (D) to obtain a solution of a titanium oxide-dispersed specific polymer (hereinafter, also referred to as “polymer (i)”) having a total solid content concentration of 20%. To 100 parts of the solution of the polymer (i), an alkyl sulfate ester salt as an emulsifier and 10% aqueous ammonia were added at a temperature of 30 ° C. or lower and mixed well to adjust the pH to 7.5. Then, it was diluted with 100 parts of i-propyl alcohol, and the obtained solution was gradually added to 200 parts of ion-exchanged water over 2 hours to form an emulsion. To this emulsion, 4 parts of adipic acid dihydrazide as a polyfunctional hydrazine derivative (G) was added, and then i-propyl alcohol and water were removed from this emulsion under reduced pressure at a temperature of 50 ° C. or lower to increase the total solid content concentration to 20. The composition was adjusted to% (II) to obtain a composition (hereinafter, also referred to as “(II-1)”).