JPH0559330A - Antifouling method for coating film surface - Google Patents

Abstract

PURPOSE:To provide the title surface excellent in antifouling capability, suitable for facing construction materials such as outer wall materials or roofing materials. CONSTITUTION:The objective antifouling method characterized by modifying coating film surface by corona discharge treatment of the coating film surface produced by curing a coating containing a polysiloxane resin as vehicle component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing adhesion of stains on a coating film surface suitable for outer wall materials such as curtain walls and exterior building materials such as roofing materials.

[0002]

2. Description of the Related Art Conventionally, the coating film surface of exterior building materials such as curtain walls is used outdoors, so that it is polluted early by mud stains, dust, bird droppings, dead insects, raindrops, etc. There is a problem of damaging. In order to solve this problem, a method for smoothing the coating surface, a method for increasing the water and oil repellency of the coating surface, a method for reducing the surface resistivity of the coating surface to prevent electrification, etc. have been studied. It was However, none of the above-mentioned methods has a sufficient stain adhesion preventing effect, and a better stain adhesion preventing method has been demanded.

[0003]

In order to solve the above problems, the inventors of the present invention have made earnest studies on a method capable of preventing stains on the surface of a coating film even when used outdoors. As a result, polysiloxane resin is used as a vehicle component. The inventors have found that it is possible to prevent the adherence of stains on the surface of the coating film by subjecting the surface of the cured coating film containing the coating material to corona discharge treatment, and completed the present invention.

That is, the present invention is characterized in that the coating film surface is modified by subjecting the coating film surface obtained by curing a coating material containing a polysiloxane resin as a vehicle component to corona discharge treatment. The present invention provides a method for preventing stain adhesion.

The coating material containing the polysiloxane resin as a vehicle component in the present invention may have a vehicle component consisting only of the polysiloxane resin, or may be a combination system of the polysiloxane resin and other components.

The polysiloxane resin of the present invention is not particularly limited as long as it is a resin having a large number of siloxane bonds, and the following are typical examples of the polysiloxane resin of the present invention. (1) The polysiloxane resin previously proposed by the applicant (Japanese Patent Laid-Open No. 59-646).
No. 71), which is an organosilicon compound represented by the following general formula (1) and / or a low condensation product thereof:

[0007]

[Chemical 1] (However, R is a hydrocarbon group having 1 to 8 carbon atoms)

Organosilicon compounds represented by the following general formula (2) and / or low condensation products thereof

[0009]

[Chemical 2] (However, R'is a hydrocarbon group having 1 to 12 carbon atoms, and R is the same as above)

A polysiloxane resin obtained by hydrolyzing a mixture of and in the presence of an acid catalyst, and then condensing the mixture at a pH of 7 or higher.

(2) The present applicant has previously proposed (Japanese Patent Laid-Open No. 62-62-62).
275132), which is a copolymer of a vinyl monomer and a polysiloxane-based macromonomer, wherein the polysiloxane-based macromonomer has the general formula

[0012]

[Chemical 3]

(In the formula, R ₁ represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a phenyl group, and R ₂ , R ₃ and R ₄ represent an alkoxyl group having 1 to ₄ carbon atoms or a hydroxyl group.)
Compound (A) represented by 70 to 99.999 mol%
And the general formula

[0014]

[Chemical 4]

(In the formula, R ₅ represents a hydrogen atom or a methyl group, and R ₆ , R ₇ and R ₈ represent a hydroxyl group, an alkoxyl group having 1 to 4 carbon atoms or an aliphatic hydrocarbon group having 1 to 8 carbon atoms. However, all of R ₆ , R ₇ and R ₈ have 1 to 1 carbon atoms.
8 is not an aliphatic hydrocarbon group. n shows the integer of 1-6. ) Compound (B) 30-0.0
It is obtained by reacting with 01 mol%.

The hydrocarbon group represented by R in the general formula [1] in the above (1) is an alkyl group such as methyl, ethyl, propyl and hexyl, an aryl group such as phenyl, tolyl and xylyl, cyclohexyl, cyclobutyl and cyclopentyl. And a cycloalkyl group. Specific examples of the compound include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetraphenoxysilane.
The low condensate means an oligomer having a polymerization degree of 10 or less.

R in the organosilicon compound represented by the general formula [2] is the same as in the general formula [1]. On the other hand, R'is a hydrocarbon group having 1 to 12 carbon atoms which is bonded to silicon by a carbon-silicon bond, and examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, hexyl and octyl, phenyl, tolyl, xylyl, Examples include aryl groups such as naphthyl, cycloalkyl groups such as cyclohexyl, cyclobutyl, cyclopentyl, and the like. Specific examples of the compound include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

The compound of the general formula [1] and / or
When a low-condensation product and a compound of the general formula [2] and / or a low-condensation product thereof are used to obtain a polycondensation resin that is a high-condensation product, the mixing ratio of both components is as follows based on the weight. It is suitable to mix in a ratio. [1] Compound and / or low condensate thereof: 5 to 95% by weight, preferably 20 to 80% by weight [2] Compound and / or low condensate thereof: 5 to 95% by weight, preferably 20 to 80% by weight In the above formulation, when the amount of the [1] compound and / or its low condensate is less than 5% by weight, that is, when the [2] compound and / or its low condensate exceeds 95% by weight, it is formed. The coating film has poor curability. When the amount of the compound [2] and / or its low condensate is less than 5% by weight, that is, the amount of the compound [1] and / or its low condensate exceeds 95% by weight, the coating film is It has the drawback that it tends to cause cracks and peeling.

When the mixture of the organosilicon compounds represented by the above general formulas [1] and [2] and / or the low condensation product thereof is condensed, the mixture of the compound and / or the low condensation product is dissolved in a water-soluble solvent. For example, it is added to an alcohol solvent, a cellosolve solvent, a cellosolve acetate solvent, a glyme solvent, etc., and bonded to Si in the presence of a mineral acid such as hydrochloric acid, sulfuric acid, phosphoric acid or an organic acid such as formic acid, acetic acid. Water is added at a ratio of 0.2 to 2 mol with respect to 1 mol of the RO group, and the mixture is reacted at 20 to 100 ° C. for about 30 minutes to 10 hours with stirring, and then inorganic such as sodium hydroxide or potassium hydroxide. Bases, aliphatic amines such as monoethylamine, diethylamine, triethylamine and the like, ammonia and the like are added to bring the pH of the system to 7 or more to proceed the condensation reaction. After the completion of the reaction, the remaining water is removed by distillation, azeotropic distillation, etc., so that the desired polysiloxane resin can be easily obtained. This polysiloxane resin is a three-dimensional condensate having a condensation degree of at least 20 and a molecular weight of about 3
It is more than 000.

In the polysiloxane macromonomer in the above (2), the main skeleton is composed of siloxane bonds, and Si of the main skeleton has an aliphatic hydrocarbon group, a phenyl group, a hydroxyl group, an alkoxyl group, a polymerizable unsaturated bond, etc. Are directly or indirectly bound to each other and are obtained by reacting the compound (A) represented by the general formula [3] with the compound (B) represented by the general formula [4]. There are 2 free functional groups selected from a hydroxyl group and an alkoxyl group per molecule of the polysiloxane macromonomer.
There are more than one.

In the above compound (A), R ₁ represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a phenyl group, and R 1
₂ , R ₃ and R ₄ represent an alkoxyl group having 1 to ₄ carbon atoms or a hydroxyl group. R _2, R ₃ and R ₄ are not permissible be different partially or entirely all be the same. In the compound (A), examples of the alkoxyl group having 1 to 4 carbon atoms include linear or branched ones such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like. As the aliphatic hydrocarbon group of, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group,
Examples thereof include linear or branched ones such as hexyl group, heptyl group, octyl group and the like.

In the above compound (A), R ₁ is particularly preferably a methyl group or a phenyl group. As R ₂ , R ₃ and R ₄ , a methoxy group, an ethoxy group, a propoxy group, a ptooxy group and a hydroxyl group are particularly preferable. Preferred specific examples of the compound (A) include methyltrimethoxysilane, phenyltrimethoxysilane, butyltrimethoxysilane, methyltriethoxysilane, methyltryptoxysilane, phenyltrisilanol, and methyltrisilanol. Of these, methyltrimethoxysilane, phenyltrimethoxysilane, phenyltrisilanol and the like are particularly preferably used. Compound (A)
Can be used alone or in combination.

In the above compound (B), R ₅ represents a hydrogen atom or a methyl group, R ₆ , R ₇ and R ₈ are hydroxyl groups,
An alkoxyl group having 1 to 4 carbon atoms or an aliphatic hydrocarbon group having 1 to 8 carbon atoms is shown. n shows the integer of 1-6. R ₆ ,
All R ₇ and R ₈ may be different partially or entirely be the same, but all should not be an aliphatic hydrocarbon group having 1 to 8 carbon atoms.

As the aliphatic hydrocarbon group having 1 to 8 carbon atoms and the alkoxyl group having 1 to 4 carbon atoms in the compound (B), the same ones as those in the compound (A) can be mentioned. R ₆ , R ₇ and R ₈ are particularly preferably a methoxy group, an ethoxy group or a hydroxyl group, and n is particularly preferably in the range of 2-4. Specific preferred examples of the compound (B) include γ-methacryloxypropyltrimethoxysilane,
γ-methacryloxypropyltriethoxysilane, γ-
Examples thereof include acryloxypropyltriethoxysilane, γ-methacryloxybutyltriethoxysilane and γ-acryloxypropyltrisilanol. Of these, γ-methacryloxypropyltrimethoxysilane,
γ-methacryloxypropyltriethoxysilane, γ-
Acryloxypropyltrisilanol and the like are particularly preferable. The compound (B) can be used alone or in appropriate combination.

The polysiloxane macromonomer in the above (2) is obtained by mixing the compound (A) and the compound (B) and reacting them. The mixing ratio of both compounds is 70 to 99.999 mol% of compound (A), preferably 90 to 90, based on the total amount of both compounds.
99.9 mol%, more preferably 95 to 99 mol%, compound (B) 30 to 0.001 mol%, preferably 10
˜0.1 mol%, more preferably 5-1 mol%. When the amount of the compound (A) is less than 70 mol%, gelation is likely to occur in the copolymerization reaction, while when it is more than 99.999 mol%, the amount of unpolymerized polysiloxane increases and the resin liquid becomes turbid, which is not preferable.

The reaction between the compound (A) and the compound (B) is
It is carried out by dehydration condensation of the hydroxyl groups of both compounds or the hydroxyl groups formed by hydrolysis of the alkoxyl groups. At this time, not only dehydration condensation but also partial dealcoholization condensation occurs depending on the reaction conditions. This reaction can be carried out without a solvent, but is preferably carried out using an organic solvent capable of dissolving the compound (A) and the compound (B) or water as a solvent. In the reaction between the compound (A) and the compound (B), the reaction temperature is usually about 20 to 180 ° C, and preferably about 50 to 120 ° C. The reaction time is usually about 1 to 40 hours.

In the production of this polysiloxane macromonomer, tetraalkoxysilane or dialkyldialkoxysilane may be added to the reaction system of the compound (A) and the compound (B) without any problem. About 20 mol% or less of both compounds can be added. In the reaction between the compound (A) and the compound (B), R
_{When 2} , R ₃ , R ₄ , R ₆ , R ₇ and R ₈ are all hydroxyl groups. Dehydration condensation is preferably carried out in an organic solvent with heating and stirring.

When the compound (A) and / or the compound (B) has an alkoxyl group bonded to Si, it is preferably hydrolyzed prior to the condensation, and usually heated and stirred in the presence of water and a catalyst. By doing so, the hydrolysis reaction and the condensation reaction can be continuously performed. The amount of water used in this case is not particularly limited, but is preferably about 0.1 mol or more per mol of the alkoxyl group. If the amount is less than about 0.1 mol, the reaction of both compounds may decrease. The most preferable method is a method using water as a solvent in a large excess. Further, in this reaction, if water and a water-soluble organic solvent are used in combination, the reaction system can be made uniform even when a sparingly soluble alcohol is produced by condensation. As the water-soluble organic solvent, those of alcohol type, ester type, ether type, ketone type and the like can be preferably used.

As the catalyst for the hydrolysis reaction, an acid catalyst or an alkali catalyst can be used. Specifically, as the acid catalyst, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid or the like can be used. Sodium hydroxide, triethylamine, ammonia, etc. can be used as the alkali catalyst. The addition amount of the catalyst is the above compound (A)
The total amount of the compound (B) and the compound (B) is about 0.0001 to 5% by weight, preferably 0.01 to 0.1% by weight.

The polysiloxane macromonomer obtained as described above has a number average molecular weight of 400 to 1000.
It is about 00, preferably about 1000 to 20000. If the number average molecular weight is less than about 400, gelation tends to occur during copolymerization, and if it exceeds about 100,000, the compatibility tends to decrease, such being undesirable. The main skeleton of the obtained polysiloxane-based macromonomer is composed of siloxane bonds, and the structure of the main skeleton is mainly composed of a long chain, a ladder, or a mixed system thereof. Among these, it is preferable to use one having a ladder-like structure or a mixed system having many ladder-like portions from the viewpoint of water resistance, heat resistance, light resistance and the like.

The polysiloxane macromonomer has a polymerizable unsaturated bond of 0.2 to 10 on average per molecule.
It is preferable to have 1.9 pieces, more preferable to have 0.6 to 1.4 pieces, and most preferable to have 0.9 to 1.2 pieces. If the amount of polymerizable unsaturated bonds is too small, the copolymerization reaction product of the macromonomer and vinyl monomer tends to become cloudy, while if the amount of polymerizable unsaturated bonds is too large, gelation may occur during the copolymerization reaction. It is not preferable.

Vinyl monomers copolymerizable with the polysiloxane macromonomer obtained as described above include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate and acrylic acid. Butyl, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, etc. Acrylic acid or methacrylic acid and monohydric alcohol having 1 to 22 carbon atoms Ester with; carboxyl group-containing vinyl monomer such as acrylic acid, methacrylic acid, maleic anhydride; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, methyl ester Hydroxyalkyl esters such as acrylic acid hydroxypropyl; FA-1, FA-
3, FM-3 (all trade names, manufactured by Daicel) and the like, an adduct of hydroxyalkyl ester of acrylic acid or methacrylic acid with ε-caprolactone; glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl Epoxy group-containing vinyl monomers such as acrylate and 3,4-epoxycyclohexyl methyl methacrylate; amide vinyl monomers such as acrylamide, methacrylamide, N-methylol acrylamide, and N-methylol methacrylamide; dimethylaminoethyl methacrylate and 2-diethylaminoethyl methacrylate. , Amino-based vinyl monomers such as tert-butylaminoethyl methacrylate; styrene, vinyltoluene, acrylonitrile, methacrylonitrile, α-
Other vinyl monomers such as methylstyrene and vinyl acetate: etc. and compounds having one polymerizable unsaturated bond in one molecule.

The copolymerization reaction between the polysiloxane macromonomer and the vinyl monomer can be carried out in the same manner as in the usual method for synthesizing an acrylic resin or a vinyl resin. For example, the both components are dissolved or dispersed in an organic solvent to give a radical. Copolymerization can be performed by heating in the presence of a polymerization initiator while stirring at a temperature of about 60 to 180 ° C.
The reaction time may be usually about 1 to 10 hours. The composition ratio of the both components in this copolymerization reaction can be arbitrarily selected according to the purpose, but the polysiloxane macromonomer is contained in an amount of 5 to 95% by weight based on the total amount of the both components.
Degree, preferably about 10 to 70% by weight, vinyl monomer about 95 to 5% by weight, preferably 90 to 30% by weight
The degree is suitable.

In the copolymer obtained as described above, the polysiloxane portion of the polysiloxane macromonomer has a long chain or ladder structure as a side chain, and is extremely excellent due to the presence of the side chain. It has surface characteristics, and the functional group bonded to Si in the side chain has high reactivity, good crosslinkability, and good compatibility with other components.

The polysiloxane resin obtained in the above (1) and (2) is a vehicle component of the paint, but the vehicle component of the paint used in the method of the present invention may be composed of only the polysiloxane resin. However, it may be a combination system of a polysiloxane resin and other components. As the other component that can be used in combination with the polysiloxane resin as the vehicle component, a resin compatible with the polysiloxane resin can be used, and examples thereof include an epoxy resin, an acrylic resin, and a polyester resin. A curing agent can also be used together.

For example, the polysiloxane resin, which is the copolymer obtained in the above (2), is disclosed in Japanese Patent Application Laid-Open No.
As described in JP-A-75379, a resin containing two or more epoxy groups and a curing agent can be used in combination. The resin containing two or more epoxy groups is homopolymerized with a polymerizable unsaturated monomer having an epoxy group by a known polymerization method such as a solution polymerization method, or is copolymerized with another copolymerizable monomer. It can be obtained by copolymerizing with a polymerizable monomer.

Typical examples of the polymerizable unsaturated monomer having an epoxy group include glycidyl methacrylate,
Aliphatic epoxy monomers such as glycidyl acrylate and allyl glycidyl ether; and alicyclic epoxy monomers such as 3,4-epoxycyclohexylmethyl methacrylate and 3,4-epoxycyclohexylmethyl acrylate. Is preferable from the viewpoint of curability.

Specific examples of the copolymerizable monomer which can be copolymerized with the polymerizable unsaturated monomer having an epoxy group include those exemplified as the vinyl monomer which is copolymerized with the polysiloxane macromonomer. The thing which removed the monomer is mentioned.
The compounding amount of the epoxy group-containing vinyl monomer in the monomer component is about 3 to 100% by weight, preferably about 20 to 100% by weight. The resin containing two or more epoxy groups obtained as described above preferably has 2 to 40 epoxy groups and has a number average molecular weight of 3,000 to 2,000.
It is preferably about 00, more preferably about 5000 to 80,000.

As the curing agent that can be used in combination with the resin containing two or more epoxy groups, an aluminum chelate compound, a titanium chelate compound and a zirconium chelate compound are used. Further, among these chelate compounds, a chelate compound containing a compound capable of forming a keto-enol tautomer as a ligand forming a stable chelate ring is preferable.

Examples of the compound capable of forming the keto-enol tautomer include β-diketones (acetylacetone etc.), acetoacetic acid esters (methyl acetoacetate etc.),
Malonates (ethyl malonate, etc.), ketones having a hydroxyl group at the β position (diacetone alcohol, etc.), aldehydes having a hydroxyl group at the β position (salicylaldehyde, etc.), esters having a hydroxyl group at the β position ( Methyl salicylate) or the like can be used. Particularly, preferable results are obtained by using acetoacetic acid esters and β-diketones.

Typical examples of these chelate compounds are diisopropylate ethylacetoacetate aluminum, tris (ethylacetoacetate) aluminum, tris (n-propylacetoacetate) aluminum, tris (isopropylacetoacetate) aluminum, tris (n). -Butylacetoacetate) aluminum, isopropoxybisethylacetoacetate aluminum, diisopropoxyethylacetoacetate aluminum, tris (acetylacetonate) aluminum, tris (ethylacetonate) aluminum,
Diisopropylate ethylacetonato aluminum, monoacetylacetonato bis (ethylacetonato) aluminum, monoethylacetoacetate bis (acetylacetonate) aluminum, tris (isopropylate) aluminum, tris (sec-butyrate) aluminum, diisopropylate Aluminum chelate compounds such as rate mono-sec-butoxyaluminum and tris (acetylacetone) aluminum: diisopropoxy bis (ethylacetoacetate) titanate, diisopropoxy bis (acetylacetate) titanate, diisopropoxy bis (acetylacetone) Titanium chelate compounds such as titanate: tetrakis (acetylacetone) zirconium, tetrakis (n-propylacetoacetate) zirco Um, it can be exemplified tetrakis (acetylacetonato) zirconium, tetrakis (ethylacetoacetate) zirconium chelate compounds such as zirconium.

The compounding amount of the chelate compound as the curing agent is 0.1 to 30 parts by weight based on 100 parts by weight of the total amount of the polysiloxane resin which is a copolymer and the resin containing two or more epoxy groups. , Preferably 0.1 to 5 parts by weight.

When the polysiloxane resin, which is a copolymer, contains an epoxy group-containing vinyl monomer as a vinyl monomer that can be copolymerized with the polysiloxane macromonomer, the epoxy group is present in the polysiloxane resin, and curing is difficult. Because of the contribution, even if the resin containing two or more epoxy groups is not blended, the same effect as that of the blended resin can be obtained.

Further, a composition prepared by blending the polysiloxane resin which is the above-mentioned copolymer, a curing agent and, if necessary, a resin containing two or more epoxy groups is further added, if necessary, in at least one molecule. A low molecular weight compound having a number average molecular weight of 2000 or less and containing two oxirane groups can be blended. This low molecular weight compound serves as a reactive diluent, and by adding it to the coating composition it can lower the viscosity of the coating and increase the solid content, and since there are few by-products during curing, it is uniform. It is possible to obtain a high solid paint having excellent curability and the like. Further, even when it is cured, there are few creases, and the coating film has excellent smoothness.

As the low molecular weight compound having a number average molecular weight of 2000 or less and containing at least two oxirane groups in one molecule, which can be used as necessary, for example, a compound represented by the following general formula:

[0046]

[Chemical 5]

And an adduct of the following polyisocyanate compound.

Examples of the polyisocyanate compound which can be used in the synthesis of the above-mentioned adduct include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate: xylylene diisocyanate or cycloaliphatic diisocyanates such as isophorone diisocyanate: tolylene diisocyanate. Isocyanates or organic diisocyanates such as aromatic diisocyanates such as 4,4'-cyphenylmethane diisocyanate itself, or adducts of each of these organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins or water, or as mentioned above. Polymers of each organic diisocyanate, such as isocyanate, and burette of isocyanate are listed. The Te "BARNOCK D-750, -8
00, DN-950, -970 or 15-455 "
[These are products of Dainippon Ink and Chemicals, Inc.], "Desmodur L, NHL, IL or N3390" [Products of Bayer AG, West Germany], "Takenate D-102,-"
202, -110N or -123N "[Takeda Pharmaceutical Co., Ltd. product]," Coronate L, HL, EH or 203 "[Japan Polyurethane Industry Co., Ltd. product] or" Duranate 24A-90CX "[Asahi Kasei Co., Ltd.]
Product] etc.

Further, as the low molecular weight compound,

[0050]

[Chemical 6]

An ester compound having an unsaturated group such as (for example, an ester compound having a number average molecular weight of about 900 obtained by an esterification reaction of tetrahydrophthalic anhydride, trimethylolpropane, 1,4-butanediol, etc.) Examples thereof include those obtained by oxidation with acetic acid and the like.

The above-mentioned (2) polysiloxane resin which is a copolymer, a curing agent and, if necessary, a resin containing two or more epoxy groups, and if necessary, at least two oxirane groups in one molecule. Number average molecular weight of 200
When a solvent is blended, the curing reaction of a coating material having a low molecular weight compound of 0 or less as a vehicle component is started by the volatilization of the solvent and proceeds in a chain by the volatilization of the chelating agent from the curing agent. Conceivable. It is presumed that the progress of the curing reaction by the curing agent follows the mechanism shown below.

For example, when an organoaluminum chelate compound is used as a curing agent, the first step reaction is that after the chelating agent volatilizes, the aluminum compound reacts with the silanol group in the polysiloxane macromonomer to form Al-- O-Si bond is generated. Then, as the second step reaction, the silanol group is coordinated to the Al-O-Si bond.

[0054]

[Chemical 7]

And polarize the silanol groups. This polarized silanol group reacts with the epoxy group to form oxonium chloride.

[0056]

[Chemical 8]

It becomes Then, ionic polymerization of the epoxy group and addition reaction to the hydroxyl group occur.

Further, it is presumed that the curing reaction proceeds when various reactions such as condensation reaction between silanol groups occur concurrently with the crosslinking reaction by the catalytic action of the curing agent described above. It seems that various curing reactions such as (A) Condensation of silanol groups with each other (B) Condensation of silanol groups with hydroxyl groups generated from oxirane groups (C) Addition of silanol groups to oxirane groups (D) Addition of hydroxyl groups to oxirane groups (E) With oxirane groups Ionic polymerization of

In the coating composition, when the polysiloxane macromonomer contains an alkoxyl group as a functional group (that is, contains an alkoxysilane group), hydrolysis is required to generate a silanol group. However, this hydrolysis reaction sufficiently proceeds even in the presence of a small amount of water such as the humidity in the air.

The coating material used in the method of the present invention contains a polysiloxane resin as a vehicle component, such as the polysiloxane resin of the above (1) or (2), or a composition obtained by combining these polysiloxane resins with other components. In addition to the vehicle component, a paint, solvent,
A paint additive such as a paint surface modifier can be blended.

Examples of the pigment include extenders such as talc, barita, clay, calcium carbonate and silica: titanium oxide, red iron oxide, carbon black, copper phthalocyanine blue, copper phthalocyanine green, flavans yellow, organic red pigment, metal oxide. Coloring pigments such as fired pigments; volatile mica powder, mica-like iron oxide, aluminum powder, stainless powder, and other volatile powders can be added.

Examples of the solvent include hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, ethers such as dioxane and ethylene glycol diethyl ether. A solvent such as an alcohol solvent such as butanol or propanol may be added.

In the method of the present invention, the coating containing the above-mentioned polysiloxane resin as a vehicle component is directly applied to a base material, or an undercoating coating is applied to the base material and is applied in a cured or uncured state. It is applied on top and cured.
As the above-mentioned base material, cement-based, calcium silicate-based,
Inorganic base materials such as gypsum-based, asbestos-based, and ceramic-based, specifically, lightweight cellular concrete (ALC), precast concrete, asbestos cement board, pulp cement board, GRC calcium silicate board, magnesium carbonate board,
Gypsum board, hard board, perlite board, etc.,
Examples of the metal plate include iron and aluminum. Paints containing a polysiloxane resin as a vehicle component include, for example, air spray coating, airless spray coating, brush coating,
It can be coated by means of roller coating, flow coating, dip coating, etc., and the coating amount (g / m ² ) is 50 to 600, preferably 100.
~ 400. In addition, the curing conditions of the above paint are
It may be appropriately selected depending on the kind of the base material, for example, it is usually dried at room temperature for about 8 hours to 3 days, or 50 to 24.
It can be cured by heating at 0 ° C. for about 30 seconds to 4 hours.

In the method of the present invention, the surface of the cured coating film obtained as described above is subjected to corona discharge treatment to modify the surface of the coating film. The treatment conditions of the corona discharge treatment are not particularly limited, but the current value is usually 10 ⁻⁵ to 10 ^−5.
-Perform self-sustaining intermittent discharge at ^-7 A for 1 to 30 seconds.

Although the surface energy of the coating film is increased by the corona discharge treatment, the surface energy is 50 dy.
It is desirable that the treatment be carried out so as to be n / cm or more, preferably 50 to 70 dyn / cm. Surface energy is 50 dyn /
If it is less than cm, the stain resistance improving effect is insufficient.

[0066]

The reason why the stain resistance of the coating film is remarkably improved by subjecting the surface of the cured coating film of the coating material containing the polysiloxane resin as a vehicle component to corona discharge treatment is not clear. By increasing the surface energy, the surface is made hydrophilic and the effect of cleaning the surface with water such as rainwater is increased, and the surface is more likely to absorb moisture, so the antistatic effect is increased. It is believed that this is due to the fact that it is prominent in the coating film in which the resin is the vehicle component.

[0067]

EFFECTS OF THE INVENTION By curing a coating film of a coating material containing a polysiloxane resin as a vehicle component by corona discharge treatment to modify the surface, the surface of exterior building materials, which has been a problem until now, has not been changed without changing the appearance. It is possible to prevent adhesion of dirt such as raindrops and maintain a good appearance.

[0068]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the following, "part" and "%" are based on weight. Production Example 1 62 parts of tetraethoxysilane, 125 parts of methyltriethoxysilane and 187 parts of ethyl alcohol were added to a reaction vessel, and the contents were heated with stirring to 80 ° C., and then 30 parts of 0.2N-hydrochloric acid was added. The mixture was added and reacted at 80 ° C. for 10 hours. Then, 30 parts of triethylamine was added to this reaction product to raise the pH to 7 or more and the condensation reaction was carried out at 80 ° C. for 2 hours, and then 100 parts of benzene was added to remove the solvent until the nonvolatile content became 40%. It was The reaction product (varnish) thus obtained was transparent and had a viscosity of 5.8 centipoise. 20 parts of titanium white was uniformly dispersed in 100 parts of the obtained varnish (a) having a solid content of 40% to obtain a coating material A.

Production Example 2 Mixture of 3,4-epoxycyclohexyl methacrylate 30 parts n-butyl methacrylate 35 parts isobutyl methacrylate 10 parts 2-hydroxyethyl acrylate 10 parts styrene 15 parts azobisisobutyronitrile 0.8 parts. Was added dropwise to 100 parts of xylene held for 3 hours and further held at the same temperature for 5 hours to obtain a transparent epoxy group-containing polymer solution (b). The number average molecular weight of the obtained polymer was about 40,000. The solid content of the polymer solution was about 50%. To 40 parts of the epoxy group-containing polymer solution (b) obtained above, 75 parts of the varnish (a) obtained in Production Example 1 and 25 parts of titanium white were mixed and uniformly dispersed to obtain a coating material B. ..

Production Example 3 Production of polysiloxane macromonomer Methyltrimethoxysilane 2720 parts γ-methacryloyloxypropyl trimethoxysilane 256 parts Deionized water 1134 parts 60% hydrochloric acid 2 parts Hydroquinone 1 part Reacted for hours. The number average molecular weight of the obtained polysiloxane macromonomer is 20.
It had one vinyl group (polymerizable unsaturated bond) and four hydroxyl groups per molecule on average. A copolymer was produced using the obtained macromonomer.

Preparation of Copolymer-1 Polysiloxane Macromonomer 300 parts 3,4-Epoxycyclohexylmethyl methacrylate 150 parts Styrene 150 parts 2-Ethylhexyl Methacrylate 230 parts 2-Hydroxyethyl acrylate 120 parts Azobisisobutyronitrile 50 parts of the mixture was dropped into 1000 parts of xylene kept at 120 ° C. and polymerized to obtain a transparent copolymer. The number average molecular weight was about 30,000. The solid content of the obtained copolymer-1 solution was about 49%.

Production of paint C Low molecular weight compound (c) containing alicyclic oxirane group (Note 1)
14 parts, isobutyl acetate 20 parts, xylene 5 parts and titanium white 50 parts were uniformly mixed and dispersed to obtain a pigment paste. 89 parts of the obtained pigment paste was added to the above copolymer-1.
A coating C was obtained by mixing 175 parts of the solution and 20 parts of a solution prepared by diluting 2 parts of tris (acetylacetonato) aluminum with 18 parts of acetylacetone.

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[Chemical 9] (Note 1): A compound represented by the general formula:

Production Example 4 Production of Copolymer-2 Mixture of the above polysiloxane macromonomer 300 parts styrene 100 parts n-butyl acrylate 600 parts azobisisobutyronitrile 20 parts in 1000 parts xylene held at 120 ° C. It was dropped and polymerized to obtain a transparent copolymer. The number average molecular weight was about 20,000. The solid content of the obtained copolymer-2 solution was about 50%.

Preparation of Epoxy Group-Containing Polymer 3,4-Epoxycyclohexylmethyl acrylate 70 parts n-Butyl acrylate 30 parts Azobisisobutyronitrile 5 parts 3 parts in 100 parts xylene held at 120 ° C.
The solution was added dropwise over a period of time, and the solution was maintained at the same temperature for 5 hours for polymerization to obtain a transparent epoxy group-containing polymer solution (d).
The number average molecular weight of this polymer was about 7,500. The solid content of the obtained epoxy group-containing polymer solution (d) was about 50.
%Met.

Production of Paint D 100 parts of the epoxy group-containing polymer solution (d), 60 parts of ethylene glycol monobutyl ether, 20 parts of xylene.
Parts and 50 parts of titanium white were uniformly mixed and dispersed to obtain a pigment paste. To 230 parts of the obtained pigment paste, 100 parts of the above copolymer-2 solution and 1.5 parts of tris (ethylacetoacetate) aluminum were added to 1 part of acetylacetone.
A coating material D was prepared by blending 15 parts of a solution diluted with 3.5 parts.

Production Example 5 TSR-116 (manufactured by Toshiba Silicone Co., Ltd., solid content: about 5)
To 100 parts of 0% methylphenylpolysiloxane varnish), 25 parts of titanium white and 10 parts of xylene were mixed and uniformly dispersed to obtain a coating E.

Production Example 6 Ethyl methacrylate 10 parts n-Butyl methacrylate 54 parts 2-Ethylhexyl methacrylate 10 parts Styrene 15 parts 2-Hydroxyethyl acrylate 10 parts Acrylic acid 1 part Azobisisobutyronitrile 3 parts A mixture at 120 ° C. 2 in 100 parts of xylene retained
The solution was added dropwise over a period of time, and the temperature was maintained for 2 hours to obtain a transparent varnish (e). The number average molecular weight of the obtained resin was about 12,000. The solid content of the varnish (e) was about 50%. To 75 parts of the above-obtained varnish (e), 21 parts of Uban 20SE (butylated melamine manufactured by Mitsui Toatsu Chemicals, Inc.) having a solid content of 60%, 20 parts of ethylene glycol monoethyl ether and 25 parts of titanium white are added. The paint F was obtained by mixing and uniformly dispersing.

Example 1 The coating material A obtained in Production Example 1 was viscously adjusted to a viscosity of about 20 seconds (Ford cup ^{# 4,} 25 ° C) with a diluting solvent, and was placed on an aluminum plate, Plasaf 500 New White (Kansai Paint Co., Ltd.).
A primer plate having a dry film thickness of about 10 μm applied thereto was coated by air spray coating so that the dry film thickness was about 20 μm, and then baked at 200 ° C. for 20 minutes to obtain a coated plate. A corona discharge treatment was performed on the coating film surface of the obtained coated plate by a self-sustaining intermittent discharge at a current value of 1 × 10 ⁻⁶ A for 5 seconds to obtain a treated coated plate.

Examples 2 to 5 and Comparative Example 6 Treatment similar to that of Example 1 except that the paint shown in Table 1 was used instead of the paint A in Example 1 and the baking conditions were as shown in Table 1. A coated plate was obtained. Comparative Examples 1-5 and Comparative Example 7 A coated plate was obtained in the same manner as in Examples 1-5 and Comparative Example 6, except that the corona discharge treatment was not performed. Comparative Examples 1 to 5 correspond to Examples 1 to 5, respectively, and Comparative Example 7 corresponds to Comparative Example 6. No difference in appearance was observed between the corresponding coated plates.

The treated coated plates and the coated plates obtained in Examples 1 to 5 and Comparative Examples 1 to 7 were exposed outdoors in Tokyo for 1 month, and the gloss of the coated surface in the state where stains adhered after exposure ( 60 ° gloss) and the degree of stain were evaluated. The degree of stain was evaluated by the difference (ΔL) in the lightness index L value from that of the unexposed coating. The 60 ° gloss and surface energy of the (treated) coated plate before exposure were also measured. The results are shown in Table 1.

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[Table 1]

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Claims (2)

[Claims] 1. A method for preventing adhesion of stains to a coating film surface, which comprises subjecting a coating film surface obtained by curing a coating material containing a polysiloxane resin as a vehicle component to corona discharge treatment to modify the coating film surface. Method. 2. The method according to claim 1, wherein the surface energy of the coating film surface is modified by corona discharge treatment to be 50 dyn / cm or more.