JP3245566B2 - 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 a problem, the present inventors have made intensive studies and as a result, the coating film formed has micropores and adheres to the surface of the coating film. The inventor of the present invention completed the present invention by assuming that a substance having a mechanism for naturally removing contaminants can maintain both functions of waterproofness and moisture permeability over a long period of time.

[0007] That is, On the surface of the moisture-permeable base material, synthetic resin emulsion to an aqueous paint and a binder, alkoxy containing modified condensate of the silane, the water vapor transmission rate according to JISK 5400 8.17 of the formed coating film is 40g / m 2 · ^24H more And JISA6909
A method for forming a moisture-permeable coating film, characterized by applying a low-contamination aqueous topcoat material having a water permeability of 0.5 ml or less according to 6.13. 2. JISK of coating film formed as undercoat material on the surface of moisture-permeable substrate
5400 water vapor permeability by 8.17 is 40g ^/ m 2 · 24
After coating the permeable water absorption prevention material of H or more, A method for forming a moisture-permeable coating film, characterized by applying the low-contamination type water-based topcoat material described in 1 above. 3. The modified condensate of alkoxysilane in the low-contamination type aqueous topcoat material has at least one or more polyoxyalkylene groups. Or 2. 3. The method for forming a moisture-permeable coating film according to item 1. 4. The modified condensate of alkoxysilane 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, and the number of carbon atoms of the repeating unit of the polyoxyalkylene group is 1 to 4, wherein 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. 5. The modified condensate of alkoxysilane 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, and the number of carbon atoms of the repeating unit of the polyoxyalkylene group is Wherein the alkoxyl group is an ethoxy group having 2 carbon atoms. Or 2. 3. The method for forming a moisture-permeable coating film according to item 1.

[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 JIS
K 5400 Measured based on 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 JIS A 6909
It is measured based on 6.13 “Permeability test B method”.
If the amount of water permeation exceeds 0.5 ml, water from rainfall penetrates into the inside of a building such as a building or civil engineering structure, and as a result,
For example, on a concrete substrate, it causes a decrease in strength due to neutralization and rusting of a reinforcing bar, and further, an abnormality such as peeling of a coating film due to excessive permeation of moisture occurs, so that the protection of the frame cannot function.

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

In the present invention, a low-contamination aqueous topcoat material containing a modified condensate of (B) an alkoxysilane is used for (A) a waterborne paint using a synthetic resin emulsion as a binder. The top coat containing the component (B) is effective because the siloxane bond in the component (B) has an appropriate bond length that allows water vapor to permeate and does not allow water to permeate in the coating. You.

Although the composition of the synthetic resin emulsion used in (A) is not particularly limited, water vapor permeation according to JIS K 5400 8.17 of a coating film formed when the synthetic resin emulsion contains the component (B) is used. The degree is 40 g / m ²
-It is essential that the water permeability according to JISA6909 6.13 is not more than 24 ml and not more than 0.5 ml.

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 modified condensate of alkoxysilane is
It acts as a stain-reducing agent, and is an essential component for imparting stain resistance and prevention of penetration of contaminants to the topcoat material of the present invention. Further, by being modified, (A) the compatibility with the water-based paint is good, and when it is used for a gloss paint, an effect that a coating film having high gloss can be formed is exhibited. 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.

(B) As the modified condensate of alkoxysilane, a product 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 them, from the viewpoint of compatibility with the synthetic resin emulsion,
An alkoxysilane condensate modified with a polyoxyalkylene group-containing compound is preferably used. When the polyoxyalkylene group is a polyoxyethylene group having 1 to 4 carbon atoms in the repeating unit and further having 2 carbon atoms, the effect of removing contaminants on the surface of the top coat by rainfall is extremely high. Therefore, it is more desirable to prevent a reduction in the moisture permeability effect due to the attachment of contaminants.

The production method (B) can be produced by the method described below, but is not limited thereto. As a specific production method of (B), for example, one or more condensates of alkoxysilane are
Examples thereof include a method of performing a transesterification reaction with one or more polyoxyalkylene group-containing substances and a method of performing an addition reaction using a coupling agent described below.

[0034] 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 the 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 is described in which the ester exchange reaction is carried out 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 and dioctyltin malate; phosphoric acid such as phosphoric acid, monomethyl phosphate, monoethyl phosphate and 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 with Coupling Agent The low-staining agent in the present invention is not only a method for introducing the component b into the component a by transesterification but also a reaction for binding the component a and the 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 for mixing the low-staining agent of (B) in the present invention, it is possible to directly add (B) to (A) an aqueous paint, or to mix (B) with this. It is also possible to add to (A) after mixing with a suitable solvent or a crosslinking agent. The amount of (B) added is based on 100 parts by weight of the solid content of the synthetic resin emulsion of (A).
It is desirable to add 1.0 to 40.0 parts by weight in terms of SiO ₂ .

Here, in terms of SiO ₂ , the weight of a compound having a Si—O bond, such as an alkoxysilane or a silicate, which is completely hydrolyzed and then converted to 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, when the mixing ratio of (A) and (B) is less than 1.0 part by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion of the overcoating material, the effect of reducing contamination can be obtained. It cannot be expressed. If it exceeds 40.0 parts by weight, the compatibility between (A) and (B) tends to decrease, and gloss paint causes a decrease in gloss.

The overcoating material of the present invention includes an alkoxysilane compound as described above as the monomer of the component a,
Alternatively, a coupling agent shown as the component d may be added in a range that does not impair the effects of the present invention.

It is preferable to add a curing catalyst to the overcoating material in the present invention. The amount of the curing catalyst added is 10
0.1 to 10 parts by weight of the curing catalyst is suitable for 0 parts by weight. If the amount is less than 0.1 part by weight, the reaction rate becomes slow, and as a result, the effect of low contamination of the cured coating film tends to decrease. If the amount is more than 10 parts by weight, the appearance and durability of the coating film tend to decrease.

As such a curing catalyst, for example,
Organic tin compounds such as dibutyltin dilaurate, dibutyltin malate, dioctyltin dilaurate, dioctyltin malate; phosphoric acid or phosphoric acid esters such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, monooctyl phosphate; propylene oxide, butylene oxide Glycidyl methacrylate, γ-glycidoxypropyltriethoxysilane, Epikote 82
Adducts of epoxy compounds such as 8 with phosphoric acid and / or acidic monophosphate esters; organic titanate compounds;
Organic aluminum compounds; organic zirconium compounds; maleic acid, adipic acid, azelaic acid, acid anhydrides thereof, acidic compounds such as paratoluenesulfonic acid; hexylamine; Examples thereof include amines such as N-dimethyldodecylamine; alkaline compounds such as sodium hydroxide. These curing catalysts can be used alone or in combination of two or more.

These curing catalysts can be added after emulsification and dispersion using a surfactant. The surfactant used is not particularly limited, but nonionic, anionic, and nonionic-anionic surfactants can be suitably used.

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 pigment, etc., which are usually used in coatings. 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 anti-sagging agents, matting agents, ultraviolet absorbers, and antioxidants can be used alone or in combination.

In the present invention, a low-contamination type water-based topcoat material can be directly applied to a substrate having moisture permeability such as concrete or mortar, but it is also possible to apply to a substrate coated with various undercoat materials. It is. In this case, the undercoat material has a water vapor permeability of 4 according to JISK 5400 8.17 for the formed coating film.
It is essential that it is 0g ^/ m 2 · 24H or more. In the present invention, it is particularly desirable to use a permeable water-absorbing prevention material as the undercoat material.

The permeable water-absorbing material penetrates deeply into a base material such as concrete or mortar to form a water-repellent layer, and blocks water or carbon dioxide gas from the outside to prevent the water from entering. It has the effect of preventing the strength from being reduced due to hydration and inhibiting the corrosion of steel frames or rebar existing inside the vehicle body.
Further, it is possible to prevent the occurrence of efflorescence on the surface layer of the base material due to the migration of the calcium component inside the base material.

In the present invention, by laminating a permeable water-absorbing material and an aqueous coating material containing an alkoxysilane-modified condensate, excellent stain resistance and long-term moisture permeability can be maintained.
Further, a coating film having excellent durability and improved physical properties such as waterproofness and efflorescence resistance can be formed. In the present invention,
By the action of the alkoxysilane-modified condensate, the topcoat material can firmly adhere to the permeable water-absorbing material having water repellency. In order to maintain the texture of a material such as concrete or brick, a permeable water-absorbing material having a clear property and a topcoat material may be applied. By the combination of the permeable water absorption preventing material of the present invention and a topcoat material,
It is also possible to prevent the occurrence of unevenness and wet color due to painting.

The permeable water-absorbing material can be used without any particular limitation as long as it has a water vapor permeability of 40 g / m ² · 24H or more, but is preferably an aqueous material in consideration of workability and environmental hygiene. . The use of an aqueous permeable water-absorbing preventive material enables coating even when the substrate contains water. As such a permeable water-absorbing material, a hydrolyzable silane compound or a silicone-based resin formed into an aqueous emulsion with various emulsifiers, or an aqueous emulsion thereof, and an acrylic resin, an acrylic silicone resin, a fluororesin, Examples thereof include composites of a synthetic resin emulsion such as a urethane resin type or a cross-linking reaction type resin type.

As the hydrolyzed silane compound, for example,
Methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, Propyltripropoxysilane,
Propyl tributoxy silane, butyl trimethoxy silane, butyl triethoxy silane, butyl tripropoxy silane, butyl tributoxy silane, dimethyl dimethoxy silane, dimethyl diethoxy silane, dimethyl dipropoxy silane, dimethyl dibutoxy silane, diethyl dimethyl silane, diethyl di Ethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane,
Examples include hexyltripropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octyltripropoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, phenyltrimethoxysilane, and vinyltrimethoxysilane. These can be used alone or as a mixture of plural types.

The osmotic water-absorbing material of the present invention includes, as necessary, a film-forming aid, an inorganic coloring pigment, an organic coloring pigment, an extender pigment, a plasticizer, a preservative, and a fungicide, which are usually used in paints. Additives such as an antifoaming agent, a leveling agent, a pigment dispersant, an anti-settling agent, an anti-sagging agent and a matting agent can be used alone or in combination.

In forming the moisture-permeable coating film of the present invention, the means for applying the low-contamination type water-based coating 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 to be applied when the low-contamination type water-based topcoat material is applied may be appropriately determined so that the water vapor permeability and the water permeability are within the range of the present invention. In this range, it may be appropriately set depending on the type of the material to be coated, the type of the base material, and the like. In the case of a flat paint, a gloss paint, and a clear paint, usually 0.1 kg / m ^{2 to} 0.5 k
The coating is performed with a coating amount of about g / m ² . The amount of application when the permeable water-absorbing material is used may be appropriately determined so that the water vapor permeability falls within the range of the present invention. In this range, may be appropriately determined by the kind of material and the substrate to be coated, ^usually performed painted coat-weight of about ^{0.05kg / m 2 ~0.4kg / m 2} , followed by a low contamination The mold water-based topcoat material is applied at the above-mentioned amount. By coating the permeable water-absorbing preventive material and the low-contamination type water-based 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.

[0063]

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 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 in the composition shown in Table 2. As the undercoat material, an aqueous emulsion-type osmotic water-absorbing material containing hexyltriethoxysilane as a main component (hereinafter, "undercoat material 1") was used.

[0067]

[Table 1]

[0068]

[Table 2]

1. Moisture permeability test Each of the undercoat material and the topcoat material was 0.20 kg / m ² ,
Spray coated on paper at a coating amount of 0.30 kg / m ² ,
After drying in a standard state for 7 days, six test pieces were cut out into a circle having a diameter of about 70 mm. Three sheets are set to the initial value, JISK
5400 A moisture permeability test was performed according to 8.17 “water vapor permeability”. The remaining three sheets were sprayed uniformly with a 15% by weight aqueous dispersion of carbon black on the entire surface of the coating film according to the JISK 5400 8.10 stain resistance test, and left in a constant temperature room at 50 ° C. for 2 hours. Thereafter, ultrasonic cleaning was carried out for 10 minutes using a sonicator, and after standing for 3 days in a standard state, a moisture permeability test was performed and evaluated in the same manner as described above. The evaluation criteria are as follows. Water vapor permeability of 40g ^/ m 2 · 24h or more: ○, 20
g ^/ m 2 · 24h more than 40g ^/ m less than 2 · 24h:
△, 20g ^/ m 2 · less than 24h: ×

2. Water permeability test The undercoating material and the topcoating material were placed on a 300 × 300 × 6 mm slate plate at 0.20 kg / m ² and 0.30 kg, respectively.
/ M ² was spray-coated at a coating amount of / m ² , and dried under standard conditions for 7 days to obtain a test specimen. After that, JISA6909 6.13
The test was performed according to the amount of water permeation.

3. Adhesion On a slate plate of 150 × 70 × 6 mm, the undercoat material and the topcoat material were respectively 0.20 kg / m ² and 0.30 kg /
A test piece was spray-coated with a coating amount of m ² and dried for 7 days in a standard state. About the prepared test plate,
JISK5400 8.5.2 Adhesion was evaluated according to the grid tape method. The evaluation was as follows: 欠 損: the area of the defective part was 5% or less, Δ: the area of the defective part was 5 to 35%, and X: the area of the defective part was 35% or more.

Table 3 shows the combinations of the undercoat material and the overcoat material and the test results. (Examples 1 to 5) 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. Did not. In addition, it can be said that the water permeability is low with respect to the high moisture permeability, and it has both functions of moisture permeability and waterproofness.

(Comparative Examples 1 and 2) When an overcoating material containing no alkoxysilane-modified condensate was used, the moisture permeability in the initial stage was sufficient, but the contaminants were not removed and the moisture permeability was reduced. Was. (Comparative Example 3) When a permeable water-absorbing preventive material and a clear topcoat material containing no alkoxysilane-modified condensate were combined, the moisture permeability in the initial stage was slightly low, and the moisture permeability after the stain resistance test was also reduced. . In addition, sufficient adhesion was not obtained.

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[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, by laminating the permeable water-absorbing material and the alkoxysilane-modified condensate-containing aqueous coating material, it has excellent durability,
A coating film having improved physical properties such as waterproofness and efflorescence resistance can be formed.

Continuation of the front page (56) References JP-A-1-281180 (JP, A) JP-A-11-290780 (JP, A) JP-A-3-127667 (JP, A) JP-A-6-73261 (JP) JP-A-63-20372 (JP, A) JP-A-8-113755 (JP, A) JP-A-10-168382 (JP, A) JP-A-1-2107082 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 5/00 B05D 7/24 302

Claims (5)

(57) [Claims] 1. A water-based coating material comprising a synthetic resin emulsion as a binder and a modified condensate of alkoxysilane contained on the surface of a moisture-permeable base material, and the formed coating film has a water vapor permeability of 40 g / JISK 5400 8.17. m ² · 24H or more, and JIS
A 6909 A method for forming a moisture-permeable coating film, characterized by applying a low-contamination aqueous topcoat material having a water permeability of 0.5 ml or less according to 6.13. 2. A coating film formed as an undercoat material on the surface of a moisture-permeable base material having a water vapor permeability of 40 g / m ² according to JIS K5400 8.17.
A method for forming a moisture-permeable coating film, comprising applying the low-contamination aqueous topcoat material according to claim 1 after applying a permeable water-absorbing material of 24H or more. 3. The moisture-permeable coating film according to claim 1, wherein the modified condensate of the alkoxysilane in the low-contamination type water-based topcoat material has at least one polyoxyalkylene group. Formation method. 4. The modified condensate of an alkoxysilane in the low-contamination type water-based topcoat material is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the polyoxyalkylene group is repeated. The method according to claim 1, wherein the unit has 1 to 4 carbon atoms, and the alkoxyl group has 1 to 4 carbon atoms. 4. 5. The modified condensate of an alkoxysilane in the low-contamination type water-based topcoat material is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the polyoxyalkylene group is repeated. The method for forming a moisture-permeable coating film according to claim 1 or 2, wherein the unit is a polyoxyethylene group having 2 carbon atoms, and the alkoxyl group is an ethoxy group having 2 carbon atoms.