JP3245575B2 - Method of forming moisture-permeable coating film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a moisture-permeable coating applied to the surface finishing of various substrates having moisture permeability, such as concrete, mortar, siding board, ALC, extruded board, and wood plywood. Things.

[0002]

2. Description of the Related Art Conventionally, paint finishing has been performed to protect a frame of a building, a civil engineering structure or the like, to impart designability, and to improve aesthetics. Among such paint finishes, waterproofing for preventing infiltration of rainwater into the inside of the skeleton is an important function from the viewpoint of protecting the skeleton of a building, a civil engineering structure, or the like. In recent years, by applying such a waterproof coating film, it has become possible to shield rainwater from entering from the outside. However, water vapor generated inside buildings and civil engineering structures, on the other hand, stays inside the building due to the moisture-blocking performance of the waterproof coating that was painted to protect the building, and in winter, the water inside the building was frozen by the inside of the building. May cause destruction of
A new problem arises in that the waterproof film is localized on the back surface and causes blistering of the film. On the other hand, with the improvement of the waterproof coating film, a new coating composition having a moisture-permeable function, which maintains the conventional waterproof performance and allows only permeation of water vapor, has been developed.

On the other hand, it has been demanded that the effect of protecting the skeleton be maintained for a long time. For this reason, with the advent of highly durable paints such as fluororesin paints, acrylic silicone resin paints, and acrylic urethane resin paints in recent years, it has become possible to drastically extend the protection effect of the frame. However, due to their durability, these highly durable paints
On the contrary, the problem of contamination of the coating film surface was brought up.

[0004] That is, even if the surface of the coating film formed by the coating material prior to the high weather resistance coating material is deteriorated by ultraviolet rays of sunlight or the like, and the contaminant adheres, the coating film is deteriorated along with the deteriorated portion of the coating film surface. Although it was peeled off, the durability of the coating film was improved, so that the mechanism of deterioration and peeling of the coating film surface could not function. In recent years, especially in urban and suburban areas, where oily contaminants are floating in the air due to exhaust gas from automobiles and other vehicles, these oily contaminants are coated with highly durable paint. If adhered to the surface, significant soot-like or streak-like contamination (hereinafter referred to as "rain streak") may occur, and the paint finish that should have been applied to improve the cityscape may not be meaningful. . This tendency is undeniable even in waterproof coatings, and contamination of the coating film surface may cause a decrease in the moisture permeability effect.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of water vapor permeability and waterproofness, while contradictory effects, and also to the stain resistance of the coating film surface, especially the natural removal effect of contaminants. Therefore, an object of the present invention is to provide a method for forming a moisture-permeable coating film that does not cause a decrease in the moisture-permeable effect over time.

[0006]

Means for Solving the Problems In order to solve such problems, the present inventors have conducted intensive studies and as a result, have found that a low-contamination type water-based coating material having a specific composition, a specific water vapor permeability and a specific amount of water permeability. It has been found that by coating, it is possible to maintain both waterproof and moisture-permeable functions for a long period of time with excellent stain resistance, and completed the present invention.

[0007] That is, (A) the following components, (B) component (C) containing components, water vapor transmission rate according to JISK 5400 8.17 of the formed coating film is 40g ^/ m 2 · 24H or more and JIS
A 6909 A method for forming a moisture-permeable coating film, characterized in that a low-contamination aqueous topcoat material having a water permeability of not more than 0.5 ml according to 6.13 is applied to the surface of a moisture-permeable substrate. (A) Synthetic resin emulsion (B) Silane-based osmotic water-absorbing inhibitor (C) Modified condensate of alkoxysilane The modified condensate of alkoxysilane (C) in the low-contamination type aqueous topcoat material has at least one or more polyoxyalkylene groups. 3. The method for forming a moisture-permeable coating film according to item 1. 3. The modified condensate of the alkoxysilane (C) in the low-contamination type aqueous topcoat material is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene groups and alkoxyl groups, and a repeating unit of the polyoxyalkylene group Wherein the alkoxyl group has 1 to 4 carbon atoms, and the alkoxyl group has 1 to 4 carbon atoms. Or 2. 3. The method for forming a moisture-permeable coating film according to item 1. 4. The modified condensate of (C) alkoxysilane in the low-contamination type water-based coating material is a modified condensate of alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, and a repeating unit of the polyoxyalkylene group A polyoxyethylene group having 2 carbon atoms,
The alkoxyl group is an ethoxy group having 2 carbon atoms. ~ 3. The method for forming a moisture-permeable coating film according to any one of the above.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The moisture-permeable substrate of the present invention is a substrate having pores containing water therein, such as concrete, mortar, ALC, gypsum board, asbestos slate board, plywood, wood, foamed foam and the like. Yes, metal plates, glass plates, plastic plates, etc. that have no air permeability are excluded.

In the present invention, the moisture permeability of the formed coating film is determined by JI
It is measured based on S K 5400 8.17 “water vapor permeability”. If water vapor permeability is less than 40g / m 2 · ^24H, steam generated inside buildings or inside civil structures is localized to coating the back surface, as a result, cause blistering of the coating film, whereas, in winter There is a danger of the frame being destroyed due to freezing inside the frame.

The water permeability of the formed coating film is measured according to JIS A
6909 Measured based on 6.13 “Permeability test B method”. When the water permeability exceeds 0.5 ml, water from rainfall penetrates into the inside of a building such as a building or a civil engineering structure. As a result, for example, on a concrete foundation, the strength is reduced due to neutralization and the rust of reinforcing steel is rusted. This causes an abnormality such as peeling of the coating film due to excessive permeation of moisture, and the protection of the frame cannot function.

According to the present invention, moisture-permeable and waterproof properties are exhibited by coating a material containing a specific component as a topcoat material and having a specific physical property value.

In the present invention, (A) a synthetic resin emulsion (hereinafter referred to as component (A)), (B) a silane-based permeable water-absorbing material (hereinafter referred to as component (B)), and (C) a modified condensation of alkoxysilane. A low-contamination type aqueous topcoat material containing a substance (hereinafter referred to as a component (C)) is used. The component (B) penetrates into the inside of the base material to increase the waterproofness, and the component (C) imparts stain resistance to the formed coating film and prevention of penetration of contaminants.

The component (A) is not particularly limited in composition, but the JIS of a coating film formed when the component (B) and the component (C) are contained in the synthetic resin emulsion.
The water vapor permeability according to K5400 8.17 is 40 g /
m ² · 24H or more, and JIS A6909 6.13
It is essential that the amount of water permeation is 0.5 ml or less.

As such a synthetic resin emulsion, any synthetic resin emulsion of acrylic resin type, acrylic silicon resin type, fluororesin type, urethane resin type, cross-linking type resin type and the like may be used.

[Acrylic resin emulsion]
As the acrylic resin-based emulsion, those obtained by radical copolymerization of an acrylic monomer and another monomer copolymerizable with the acrylic monomer can be used.

The acrylic monomer is not particularly restricted but includes, for example, methyl (meth) acrylate (indicating either methyl acrylate or methyl methacrylate; the same applies hereinafter) and ethyl (meth).
Acrylate, n-butyl (meth) acrylate, i-
Alkyl group-containing (meth) acrylic monomers such as butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate; 2
-Hydroxy group-containing (meth) acrylic monomers such as hydroxyethyl (meth) acrylate; ethylenically unsaturated carboxylic acids such as (meth) acrylic acid; dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate Amino group-containing (meth) acrylic monomers; amide-containing (meth) acrylic monomers such as (meth) acrylamide and ethyl (meth) acrylamide; nitrile group-containing (meth) acrylic monomers such as acrylonitrile An epoxy group-containing (meth) acrylic monomer such as glycidyl (meth) acrylate;

Other monomers copolymerizable with the acrylic monomer include aromatic hydrocarbon vinyl monomers such as styrene, methylstyrene, chlorostyrene and vinyltoluene; maleic acid, itaconic acid, croton Acid, fumaric acid,
Α, β-ethylenically unsaturated carboxylic acids such as citraconic acid; sulfonic acid-containing vinyl monomers such as styrene sulfonic acid and vinyl sulfonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl chloride, vinylidene chloride , Chloroprene and other chlorine-containing monomers; hydroxyethyl vinyl ether, hydroxypropyl vinyl ether and other hydroxyl-containing alkyl vinyl ethers; ethylene glycol monoallyl ether, propylene glycol monoallyl ether, diethylene glycol monoallyl ether and other alkylene glycol monoallyl ethers; ethylene and propylene And α-olefins such as isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate; methyl vinyl ether and ethyl vinyl Ether, butyl vinyl ether, vinyl ether such as cyclohexyl vinyl ether, ethyl allyl ether, an allyl ether such as butyl allyl ether and the like.

When an acrylic resin emulsion is used as the synthetic resin emulsion, durability, cost, etc.
Advantageously, there is a high degree of freedom in resin design and a high gloss in gloss paint.

[Regarding Acrylic Silicone Resin Emulsion] The acrylic silicone resin-based emulsion is obtained by radical copolymerization of a silicon-containing acrylic monomer and another monomer copolymerizable with the silicon-containing acrylic monomer. Can be used.

The silicon-containing acrylic monomer is not particularly limited. For example, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acrylic Examples include hydrolyzable silyl group-containing vinyl monomers such as roxypropylmethyldimethoxysilane and γ- (meth) acryloxypropylmethyldiethoxysilane.

As the other monomer copolymerizable with the silicon-containing acrylic monomer, for example, the monomer used in the above-mentioned acrylic resin emulsion can be used without any particular limitation.

When an acrylic silicone resin emulsion is used as the synthetic resin emulsion, weather resistance, yellowing resistance, durability, chemical resistance, stain resistance and the like are advantageous.

[Regarding Fluororesin Emulsion] As the fluororesin emulsion, a fluorine-containing monomer,
And those obtained by radical copolymerization of a fluorine-containing monomer and another copolymerizable monomer can be used.

Examples of the fluorine-containing monomer include fluoroolefins such as vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, pentafluoroethylene and hexafluoropropylene; trifluoroethyl (meth) acrylate, pentafluoropropyl (meth And fluorinated (meth) acrylates such as acrylate and perfluorocyclohexyl (meth) acrylate.

As the other monomer copolymerizable with the fluorine-containing monomer, for example, the monomer used in the above-mentioned acrylic resin emulsion can be used without any particular limitation.

When a fluororesin emulsion is used as the synthetic resin emulsion, weather resistance, yellowing resistance, durability, chemical resistance, stain resistance and the like are advantageous.

[About urethane resin emulsion]
The urethane resin-based emulsion is a generic term for emulsions having urethane bonds in a coating film after the formation of the coating film. That is, it may be one having a urethane bond before the coating film is formed, or one which forms a urethane crosslink by a reaction after the coating film is formed. The form of the emulsion may be a one-part type or a two-part type. As a one-part type, a method of copolymerizing a polymerizable monomer having a urethane bond with another copolymerizable monomer, polymerizing a polymerizable unsaturated monomer in the presence of an aqueous resin having a urethane bond how to,
Examples include a method of mixing an aqueous urethane resin having a reactive group with an emulsion containing a group capable of reacting with the reactive group. Examples of the two-pack type include a combination of a water-dispersible isocyanate and a hydroxyl group-containing emulsion.

When a urethane resin emulsion is used as the synthetic resin emulsion, durability, solvent resistance,
Advantageous are chemical resistance and stain resistance.

[Other Crosslinking Reaction Type Emulsions] In the synthetic resin emulsion, besides the above-mentioned crosslinking reaction with a hydroxyl group and an isocyanate compound, carbonyl group and hydrazide group, carboxylic acid and metal ion, epoxy group and amine, epoxy group It is also possible to use an emulsion that forms a cross-linking reaction using a carboxylic acid and aziridine, a carboxylic acid and carbodiimide, a carboxylic acid and oxazoline, an acetoacetate and ketimine, and the like. The cross-linking reaction type emulsion may be a one-component type or a multi-component type of two or more components.

When a cross-linking reaction type emulsion is used as the synthetic resin emulsion, durability, solvent resistance, chemical resistance, stain resistance and the like are advantageous.

(B) The silane-based osmotic water-absorbing agent plays a role of deeply penetrating into a base material such as concrete or mortar to form a water-repellent layer, thereby enhancing waterproofness. In addition, by preventing the intrusion of water and carbon dioxide gas from the outside, the strength of the base material is prevented from lowering due to neutralization, the corrosion of steel frames or rebar existing inside the precursor is suppressed, and the inside of the base material is further reduced. It also has an effect of preventing the occurrence of efflorescence on the surface layer of the base material due to the migration of the calcium component.

As the component (B), alkoxysilane obtained by making an aqueous emulsion with various surfactants can be used.

Examples of the alkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, Propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltripropoxysilane, butyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyl Dipropoxysilane, dimethyldibutoxysilane, diethyldimethylsilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyl Dibutoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltripropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octyltripropoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, phenyl Trimethoxysilane, vinyltrimethoxysilane, and the like. These can be used alone or as a mixture of plural types.

As the surfactant for converting the alkoxysilane into an aqueous emulsion, one selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, or Two or more can be used as appropriate. For example, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl amino ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene fatty acid ester; higher alcohol sodium sulfate, ammonium lauryl sulfate, Anionic surfactants such as triethanolamine lauryl sulfate, sodium dodecylbenzene sulfonate, sodium alkylnaphthalene sulfonate, sodium dialkyl sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate; alkylamine acetate, alkylamine hydrochloride, quaternary Cationic surfactants such as ammonium salts; alkyldimethylamine oxide, alkylcarboxymethyl Amphoteric surfactants such as mud carboxyethyl imidazolium betaine. Among them, a nonionic surfactant is preferable because it can improve the stability of the alkoxysilane compound.

The content of the component (B) is 30 to 400 parts by weight (preferably 120 to 200 parts by weight) based on 100 parts by weight of the solid content of the component (A).
When the amount of the component (B) is less than 30 parts by weight, the water-repellent layer is not sufficiently formed, and the water absorption preventing property, the neutralizing preventing property, the corrosion preventing property, the eflorescence generating preventing property and the like are deteriorated. 400
If the amount is more than 10 parts by weight, sufficient film-forming ability cannot be obtained,
Durability, waterproofness, etc. are reduced.

(C) The modified condensate of alkoxysilane is
It acts as a low-staining agent, and is an essential component for imparting stain resistance, prevention of penetration of contaminants, and moisture permeability to the topcoat material of the present invention. Also,
By being modified, the compatibility with the component (A) is good, and when it is used for a gloss paint, it has an effect of forming a coating film having high gloss.
When an unmodified alkoxysilane is used, it has poor compatibility with the synthetic resin emulsion, and causes problems such as generation of foreign matter in the paint and reduction in gloss of the paint film with gloss paint.

As the component (C), one obtained by modifying an alkoxyl group of an alkoxysilane with a polyoxyalkylene group-containing compound, an amino group-containing compound, a fluorine-containing compound, or the like is used. Among these, an alkoxysilane condensate modified with a polyoxyalkylene group-containing compound is preferably used from the viewpoint of compatibility with the synthetic resin emulsion. As the polyoxyalkylene group, when the repeating unit is a polyoxyethylene group having 1 to 4 carbon atoms and further having 2 carbon atoms,
Since the effect of removing contaminants on the surface of the top coat by rain is greatly enhanced, it is more desirable to prevent a decrease in the moisture permeability effect due to the attachment of contaminants.

The component (C) can be produced by the method described below, but is not limited thereto.

As a specific production method of the component (C),
For example, a method in which one or more condensates of an alkoxysilane is transesterified with one or more polyoxyalkylene group-containing substances, and a method in which an addition reaction is performed using a coupling agent described later.

[0040] i) transesterification reaction i.e., the general formula _{^{(R 1 O) 4-a}} -SiR 2 a ( wherein, ^{R 1} represents an alkyl group having 1 to 4 carbon atoms, ^{R 2}
Is an alkyl group, an aryl group, an aralkyl group,
4 represents an alkoxyl group, and a represents an integer of 0 to 2)
(Hereinafter referred to as “a component”)
That. The raw material before the condensation is referred to as “a component monomer”. ) And the general formula ^{_{R 3 - (OC n H 2n}} ) m -R 4 ( wherein, ^{R 3} is a hydrogen atom or an alkyl group, an epoxy group, an acyl group, ^{R 4} is a hydroxyl group, an alkyl group, an alkoxyl group, An epoxy group, an acyl group, a carboxyl group, n is an integer of 1-4, and m is an integer of 1-20)
By transesterification with a polyoxyalkylene chain-containing compound represented by the following formula (hereinafter referred to as “component b”). In particular, in the transesterification reaction, it is necessary to have at least one or more hydroxyl groups at the terminal (this is not the case in the case of an addition reaction using a coupling agent described later). It is important to use the ingredients.

Specifically, as the monomer of the component a,
For example, tetramethoxysilane, tetraethoxysilane,
Tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetra-i-
Butoxysilane, tetra-t-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane,
Ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltributoxysilane, butyltrimethoxylan, butyltriethoxysilane, Butyl tripropoxy silane,
Examples include butyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethylsilane, diethyldiethoxysilane, diethyldipropoxysilane, and condensates of diethyldibutoxysilane. These can be used alone or as a mixture of plural types.

The alkoxysilyl group of component a has 1 carbon atom.
To 4 are preferable. When the number of carbon atoms exceeds 5, heating at a high temperature is required in the transesterification reaction between the monomer of the component a and the component b. However, since the thermal stability of the component a is inferior, the gel tends to be unusable during the transesterification reaction. The average degree of condensation of the component a is preferably 1 to 20. If the average degree of condensation exceeds 20, handling becomes inconvenient, which is not preferable.

Specific examples of the component b include polyoxyethylene glycol, polyoxyethylene glycol monoalkyl ether, polyoxyethylene-propylene glycol, polyoxyethylene-tetramethylene glycol, polyoxyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl. ether,
Polyoxyethylene diglycolic acid, polyoxyethylene glycol vinyl ether, polyoxyethylene glycol allyl ether, polyoxyethylene glycol diallyl ether, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl Amines and the like. These compounds are
One or a combination of two or more can be selected.

The average molecular weight of the component b is preferably from 150 to 2,000. If the average molecular weight is less than 150, the stability when mixing the low-staining agent obtained by transesterification with the component a into the paint tends to be poor, and excellent gloss is obtained with the gloss paint. Is gone. Conversely, if the average molecular weight of the component b exceeds 2,000, the water resistance and hardness of the cured coating film tend to decrease.

In the above, an example has been described in which the ester exchange reaction is performed after the monomer of the component a is condensed. However, a production method in which the monomer of the component a is transesterified with the component b in advance and then condensed can also be used.

In carrying out the transesterification reaction, a transesterification catalyst (hereinafter referred to as "component c") can be added.

As the component c, for example, organic tin compounds such as dibutyltin dilaurate, dibutyltin malate, dioctyltin dilaurate, dioctyltin malate; phosphoric acid such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, monooctyl phosphate; Phosphate esters; Adducts of epoxy compounds such as propylene oxide, butylene oxide, glycidyl methacrylate, γ-glycidoxypropyltriethoxysilane, and Epikote 828 with phosphoric acid and / or acidic monophosphate esters; organic titanate compounds; Aluminum compound; organic zirconium compound; maleic acid;
Acidic compounds such as adipic acid, azelaic acid, their anhydrides, and paratoluenesulfonic acid; hexylamine; Amines such as N-dimethyldodecylamine;
Curing catalysts such as an alkaline compound such as sodium hydroxide are exemplified.

Such a component c can be used alone or in combination of two or more. Component c is preferably used in an amount of 0.0001 to 5 parts by weight based on 100 parts by weight of component a. When the amount of the component c is 0.0001 parts by weight or less, the contribution to the transesterification reaction is small,
If the amount is more than 1 part by weight, the condensation reaction of the component (a) itself is accelerated, and the stability of the low-contaminating agent is undesirably reduced.

Ii) Addition reaction by coupling agent The low-contaminating agent in the present invention is not only a method of introducing component b into component a by transesterification, but also a reaction of coupling component a and component b in one molecule. It can also be produced by an addition reaction using a coupling agent having a hydrophilic functional group and one or more alkoxysilyl groups (hereinafter referred to as “d component”).

Examples of the reactive functional group for the component d include a vinyl group, an epoxy group, an amino group, an isocyanate group, and a mercapto group. Further, the functional group may be bonded to an alkoxysilyl group via a urethane bond, a urea bond, a siloxane bond, an amide bond, or the like.

As the d component, specifically, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyltriethoxysilane, β- (3,4
Epoxycyclohexyl) ethyltrimethoxysilane,
N-β (aminoethyl) γ-aminopropylmethyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane And the like.

As a method of mixing the components in the present invention, it is possible to directly add the component (C) to the water-based paint containing the components (A) and (B) in advance. )) It is also possible to add the components after mixing the components with a solvent or a crosslinking agent that can be mixed with the components.

The content of the component (C) is 1.0 to _{4 in} terms of SiO _{2 with} respect to 100 parts by weight of the solid content of the component (A).
Addition of 0.0 parts by weight is desirable.

Here, in terms of SiO ₂ , the weight of a compound having a Si—O bond, such as alkoxysilane or silicate, which is completely hydrolyzed and which remains as silica (SiO ₂ ) when calcined at 900 ° C. It is expressed in minutes.

In general, alkoxysilanes and silicates
Reacts with water and undergoes a hydrolysis reaction to form silanol.
To silanols or silanol and alkoxy
It has the property of causing more condensation reaction. Investigate this reaction
When performed up to the maximum, silica (SiO ₂). These anti
Response

Embedded image This is a conversion formula of the amount of the remaining silica component based on this reaction formula.

The actual calculation is

(Equation 1) The equation was used.

In the present invention, if the mixing ratio of the component (C) is less than 1.0 part by weight, the effect of reducing pollution cannot be exhibited. If it exceeds 40.0 parts by weight,
The compatibility between the component (A) and the component (C) tends to decrease, and gloss paint may cause a decrease in gloss.

The overcoating material of the present invention may contain, if necessary, a film-forming aid, an inorganic coloring pigment, an organic coloring pigment, an extender, and the like, which are usually used in coating materials. Further, a plasticizer, an antiseptic, a fungicide, an antifoaming agent, a leveling agent, a pigment dispersant, an anti-settling agent, which do not affect the present invention,
Additives such as an anti-drip agent, a pH buffer, a matting agent, an ultraviolet absorber, an antioxidant, and a curing catalyst can be used alone or in combination.

The overcoating material of the present invention includes a
An alkoxysilane compound as shown as a monomer of the component or a coupling agent as shown as the d component can be added within a range not to impair the effects of the present invention.

In the present invention, the pH of the overcoating material is preferably 5 to 8. By setting the content in such a range, a sufficient pot life during coating can be ensured, and the coating film properties such as stain resistance and waterproofness can be sufficiently exhibited.

In forming the moisture-permeable coating film of the present invention, the means for applying the low-contamination type water-based topcoat material and the permeable water-absorbing preventive material is not particularly limited, and may be brush coating, spray coating, roller coating, roll coater, flow coating, or the like. A known coating method such as a coater can be used.

The amount of application of the low-contamination type water-based overcoating material may be determined as appropriate so that the water vapor permeability and the water permeability fall within the range of the present invention. In this range, it may be appropriately set according to the type of the material or the base material to be coated, but in the case of flat paint, gloss paint, clear paint,
Usually, perform painting at ^25g / ^{m 2 ~250g} / m 2 about coat-weight in terms of solid content. By coating the low-contamination aqueous topcoat material at such a coating amount, a coating film having a good balance of physical properties such as moisture permeability and waterproofness can be obtained.

In order to maintain the texture of a material such as concrete or brick, a clear coating material may be applied. By using the overcoating material of the present invention, it is possible to prevent the occurrence of unevenness and wet color due to coating.

[0064]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

(Synthesis Example 1) Alkoxysilane-Modified Condensate 1 Synthesis Example Average molecular weight of 750 which is a condensate of tetraethoxysilane
100.0 parts by weight of ethyl silicate condensate (average molecular weight: 750, residual ratio of silica: 40% by weight) and an average molecular weight of 2
Then, 106.7 parts by weight of polyoxyethylene glycol # 200 (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed, and 0.02 parts by weight of dibutyltin dilaurate was further added as a catalyst, followed by a deethanolation reaction at 75 ° C. for 8 hours. Thus, an alkoxysilane-modified condensate 1 was synthesized. The ratio of the remaining amount of silica obtained by calcining the alkoxysilane-modified condensate 1 at 900 ° C. was 20.9% by weight.

(Synthesis Example 2) Synthesis Example of Alkoxysilane-Modified Condensate 2 100 parts by weight of ethyl silicate condensate, average molecular weight 4
Of polyoxyethylene glycol monocetyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was mixed with 81.7 parts by weight, and 0.02 parts by weight of dibutyltin dilaurate was added as a catalyst. Condensate 2 was synthesized. The residual ratio of silica in the alkoxysilane-modified condensate 2 was 22.2% by weight.

Using the raw materials shown in Table 1 as the overcoating materials, each overcoating material was prepared with the composition shown in Table 2.

[0068]

[Table 1]

[0069]

[Table 2]

1. Moisture permeability test The topcoat material was spray-coated on paper so as to have a dry film thickness of about 40 μm, dried for 7 days in a standard state, and then cut into six pieces having a diameter of about 70 mm to obtain a test piece. The three sheets were used as initial values and subjected to a moisture permeability test according to JIS K 5400 8.17 “water vapor permeability”. The other three are JI
SK 5400 8.10 A 15% by weight aqueous dispersion of carbon black is sprayed uniformly over the entire surface of the coating film according to the stain resistance test.
It was left in a constant temperature room at 50 ° C. for 2 hours. After that, using a sonicator, ultrasonic cleaning is performed for 10 minutes, and 3
After standing for a day, a moisture permeability test was performed and evaluated in the same manner as described above. The evaluation criteria are as follows. ○: 40g ^/ m 2 · 24h or more △: 20g ^/ m 2 · 24h more than 40g ^/ m 2 · 24h less than ×: 20g ^/ m less than 2 · 24h

2. Water permeability test The top coat material was spray-coated on a slate plate of 300 × 300 × 6 mm so that the dry film thickness was about 40 μm, and dried under standard conditions for 7 days to obtain a test specimen. Then J
The test was performed according to IS A6909 6.13 Water permeability.

Table 3 shows the test results. (Examples 1 to 4) In the moisture permeability test, the moisture permeability was high even in the initial state, and the contaminants were peeled off by ultrasonic cleaning despite the subsequent contamination treatment, so that the value of the moisture permeability decreased. Did not. Further, the water permeability was low with respect to the high moisture permeability, and both moisture permeability and waterproofness were excellent.

(Comparative Examples 1 to 3) When an overcoating material containing no alkoxysilane-modified condensate was used, contaminants were not removed and moisture permeability was reduced.

[0074]

[Table 3]

[0075]

According to the present invention, while having the contradictory effects of moisture permeability and waterproofness, the stain resistance of the coating film surface, particularly the effect of naturally removing contaminants, is extremely excellent. Can be obtained. Furthermore, since it contains a component that penetrates into the base material, a coating film having excellent waterproofness, efflorescence resistance, and the like can be formed.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-290780 (JP, A) JP-A-7-82053 (JP, A) JP-A-10-244216 (JP, A) JP-A-4- 363373 (JP, A) JP-A-64-6068 (JP, A) JP-A-8-113755 (JP, A) JP-A-10-168382 (JP, A) JP-A-5-97542 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 1/00-7/26 C09D 5/00 C09D 183/06

Claims (4)

(57) [Claims] 1. A JIS K5400 8.17 of a formed coating film containing the following components (A), (B) and (C).
Water vapor permeability due to the 40g ^/ m 2 · 24H or more and the water permeability by JIS A 6909 6.13 0.5
1. A method for forming a moisture-permeable coating film, characterized in that a low-contamination type water-based coating material having a volume of not more than 0.1 ml is coated on the surface of a moisture-permeable substrate. (A) Synthetic resin emulsion (B) Silane-based osmotic water-absorbing material (C) Modified condensate of alkoxysilane 2. The moisture-permeable coating film according to claim 1, wherein the modified condensate of (C) alkoxysilane in the low-contamination aqueous topcoat material has at least one polyoxyalkylene group. Forming method. 3. The modified condensate of alkoxysilane (C) in the low-staining aqueous coating material is a modified condensate of alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, 3. The method for forming a moisture-permeable coating film according to claim 1, wherein the repeating unit of the group has 1 to 4 carbon atoms, and the alkoxyl group has 1 to 4 carbon atoms. 4. The modified condensate of alkoxysilane (C) in the low-contamination type aqueous topcoat material is a modified condensate of alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, The moisture-permeable coating film according to any one of claims 1 to 3, wherein the repeating unit of the group is a polyoxyethylene group having 2 carbon atoms, and the alkoxyl group is an ethoxy group having 2 carbon atoms. Formation method.