JP3220085B2 - 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 surface finishing of various substrates having moisture permeability, such as concrete, mortar, siding board, ALC, extruded board, and wood plywood. It is about.

[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, on the contrary, the moisture generated by the penetration of water vapor generated inside the building or civil engineering
Due to the moisture shielding performance of the waterproof coating, it stays inside the building,
In winter, the freezing inside the skeleton caused the destruction of the skeleton, and the waterproof coating was localized on the back surface, causing new problems such as swelling of the coating. 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, The surface of the moisture-permeable base material contains a condensate of tetraalkoxysilane with an average degree of condensation of 4 to 10 with respect to the organic synthetic resin, and the formed coating film has a moisture permeability according to JISZ0208 of 40 g /
m 2 ^· 24H or more and a method of forming the moisture-permeable coating film, wherein the water permeability according to JIS A6909 6.13 to paint the following topcoat material 0.5 ml.

[0008] 2. The condensate of tetraalkoxysilane having an average degree of condensation of 4 to 10 is a condensate in which an alkyl group having 1 to 3 carbon atoms and an alkyl group having 4 to 12 carbon atoms are mixed. 3. The method for forming a moisture-permeable coating film according to item 1.

3. It is characterized by containing 1 to 50 parts by weight of a condensate of tetraalkoxysilane having an average degree of condensation of 4 to 10 in terms of SiO ₂ with respect to 100 parts by weight of the solid content of the organic synthetic resin. 3. The method for forming a moisture-permeable coating film according to item 1.

[0010] 4. For 100 parts by weight of the solid content of the organic synthetic resin, alkyl groups having 1 to 3 carbon atoms and 4 to 12 carbon atoms are mixed, and alkyl groups having 4 to 12 carbon atoms are 5 to 5 of all alkyl groups in the condensate. 2, wherein a condensate is 50%, containing 1 to 50 parts by weight in terms of SiO _2. 3. The method for forming a moisture-permeable coating film according to item 1.

5. The organic synthetic resin is a polyurethane resin; ~ 4. The method for forming a moisture-permeable coating film according to any one of the above.

6. Furthermore, the number of repeating units is 2 to 40.
An alkoxysilane compound having a weight average molecular weight of 150 to 3500 containing a polyalkylene oxide chain of 0.1 to 20 parts by weight based on 100 parts by weight of the resin solids.
It is characterized by containing 1 part by weight. ~ 5. The method for forming a moisture-permeable coating film according to any one of the above.

[0013]

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
It is measured based on Z 0208 “Method of testing moisture permeability of moisture-proof packaging material”. If the moisture permeability is less than 40g / m 2 · ^24H, buildings inside and civil structures inside water vapor generated, the water due to penetration into the interior skeleton is localized to coating the back surface, as a result, the coating film In winter, the swelling may cause swelling, while in the winter, the skeletal structure may be damaged by freezing inside the skeletal structure.

The water permeability of the formed coating film is determined according to 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, by applying a material containing a specific component and having a specific physical property value as a topcoat material, it exhibits moisture permeability and waterproofness.

As the overcoating material in the present invention, a condensate of tetraalkoxysilane having an average degree of condensation of 4 to 10 (hereinafter referred to as "component (A)") is added to an organic synthetic resin (hereinafter referred to as "component (A)").
A non-staining paint containing “(B) component” is used. 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. The average degree of condensation of the component (B) is from 4 to
About 10 is effective because the state of dispersion in the top coat is moderate. Those having an average degree of condensation of more than 10 are not preferred because they are difficult to produce and are inconvenient to handle due to an increase in viscosity. Conversely, those having an average degree of condensation of 3 or less are not preferred because of increased volatility and inconvenient handling.

The composition of the organic synthetic resin is not particularly limited, but when the organic synthetic resin contains the component (B), the formed coating film has a moisture permeability according to JISZ 0208 of 40 g / m ² ··· It is essential that the water permeability according to JIS A69096.13 is not more than 0.5 ml.

As such organic synthetic resins, aqueous resins,
Regardless of the solvent type, any organic synthetic resin such as an acrylic resin type, a urethane resin type, an acrylic silicon resin type, a fluorine type, an epoxy resin type, etc. may be used, and the form may be a dispersion type or a solution type. Furthermore, in the solvent system,
The solvent may be an aromatic hydrocarbon, an aliphatic hydrocarbon, or a mixture thereof.

Of these, polyurethane resins are preferably used from the viewpoints of moisture permeability, waterproofness, weather resistance, and economy. In particular, a non-aqueous dispersion type (hereinafter referred to as "NAD type") polyol dispersion and an isocyanate
When an AD type polyurethane resin is used, a coating film having an excellent balance between moisture permeability and waterproofness can be formed, and is most preferably used. Specifically, the weight average molecular weight is 500
0 to 150,000, a hydroxyl value of 20 to 100 KOHmg / g, and an isocyanate compounded in an NCO / OH ratio of 0.7 to 2.0 with respect to 100 parts by weight of the resin solid content of the NAD type polyol dispersion. NAD type polyurethane resin.

In the overcoating material of the present invention, the alkyl group in the component (B) is a mixture of an alkyl group having 1 to 3 carbon atoms and an alkyl group having 4 to 12 carbon atoms (hereinafter referred to as "component (B ')"). The use of is extremely advantageous in that the effect of removing contaminants on the surface of the topcoat film by rainfall is greatly enhanced, so that a decrease in the moisture permeability effect due to the attachment of contaminants is prevented.

The component (B ') of the present invention can be produced by the following method, but is not limited thereto. (Production Example 1) General formula

Embedded image ( Wherein R _{1 to} R ₄ are a mixture of an alkyl group having 1 to 3 carbon atoms and an alkyl group having 4 to 12 carbon atoms).
0, condensation is performed so that the weight average molecular weight is 500 to 2500. The condensation method is based on a known method.

(Production Example 2) (a) General formula

Embedded image ( Wherein , R ₅ is an alkyl group having 1 to 3 carbon atoms, and n is 4
(B) an alkyl silicate low-condensate represented by the following general formula (b):

Embedded image ( Wherein , R ₆ is an alkyl group having 4 to 12 carbon atoms) (hereinafter, referred to as “component (b)”) using about 5 to 5 parts of the alkyl group portion of component (a). Transesterify 50%.

As the component (a), specifically, tetramethyl silicate, tetraethyl silicate, tetra-n
Low-condensates such as -propyl silicate and tetra-i-propyl silicate. In particular, tetramethyl silicate and tetraethyl silicate are generally used. The average degree of condensation is preferably from 4 to 10, and it is not preferable that the degree of condensation is large or small because handling becomes inconvenient.
As the component (b), specifically, n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol,
n-heptyl alcohol, n-octyl alcohol, n
-Nonyl alcohol, n-decyl alcohol, n-undecyl alcohol and n-dodecyl alcohol can be exemplified.

When the component (a) is transesterified with the component (b), all the alkyl groups ( R ₅ ) of the component (a)
Is not transesterified to the alkyl group ( R ₆ ) of the component (b), but about 5% of the total alkyl group of the component (a).
５０50% transesterified is used. The exchange ratio of component (b) is 1 to 1 mole of component (a).
The transesterification may be performed using 12 moles. This exchange ratio is appropriately adjusted depending on the degree of condensation of the component (a). By transesterifying about 5 to 50% of the total alkyl groups of the component (a), the compatibility with the component (A) and the coating film Has excellent stain resistance.

Next, in the present invention, a coating film is obtained by further adding (C) an alkoxysilane compound containing a polyalkylene oxide chain (hereinafter referred to as “component (C)”) to an overcoating material containing tetraalkoxysilane. It is possible to make the surface more hydrophilic than the initial stage, and it is possible to obtain a stain resistance superior to the initial stage.

The component (C) is a compound having an alkylene oxide repeating unit and at least one alkoxysilyl group. In the polyalkylene oxide repeating unit of the component (C), the number of carbon atoms in the alkylene portion is 2 to 4, and the number of repeating units is 2 to 4.
0 and a weight average molecular weight of 150 to 3500 are preferred.

In the component (C), the both ends of the polyalkylene oxide chain may be alkoxysilyl groups, and one end may be an alkoxysilyl group and the other end may be another functional group. Good. Examples of such a functional group that can be present at one end include a vinyl group,
Examples include a hydroxyl group, an epoxy group, an amino group, an isocyanate group, and a mercapto group. Particularly, the use of a hydroxyl group (hydroxyl group) is preferred. Further, the functional group may be bonded to an alkoxysilyl group via a urethane bond, a urea bond, a siloxane bond, an amide bond, an ether bond, or the like.

As the component (C), for example, a compound synthesized by reacting a compound containing a polyalkylene oxide chain with a compound containing an alkoxysilyl group (hereinafter, referred to as a coupling agent) can be used.

Examples of such polyalkylene oxide chain-containing compounds include polyethylene glycol, polyethylene-propylene glycol, polyethylene-tetramethylene glycol, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyoxyethylene diglycolic acid, and polyethylene glycol. Examples include vinyl ether, polyethylene glycol divinyl ether, polyethylene glycol allyl ether, and polyethylene glycol diallyl ether. The polyalkylene oxide chain-containing compound can be selected from one kind or a combination of two or more kinds. When two or more types of monomers are used, they may be random copolymers or block copolymers.

On the other hand, the coupling agent is, for example, a compound having at least one or more alkoxysilyl groups and other substituents in one molecule. Specific examples of the coupling agent include β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (Aminoethyl) γ-aminopropylmethyldimethoxysilane, N-
β (aminoethyl) γ -aminopropyl trimethoxy
Orchid , γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, isocyanate-functional silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropoxymethyldiethoxysilane, γ-methacryloxypropyltrisilane Ethoxysilane and the like can be mentioned.

The synthesis of component (C) is not particularly limited, but a compound containing a polyalkylene oxide chain and a coupling agent are separately prepared. For example, a radical polymerization initiator is used for each compound having a polymerizable double bond. In addition to copolymerization using an amino group, it can be synthesized by a known method such as an addition reaction of an amino group / epoxy group, an isocyanate group / hydroxyl group or an isocyanate group / amino group. It can also be synthesized by a method in which ethylene oxide is ring-opened to an alkoxysilyl compound having an active hydrogen group such as a primary or secondary amino group.

When the copolymerization is carried out using a radical polymerization initiator, at least one or more of the polyalkylene oxide chain-containing compounds having a polymerizable double bond and at least one or more of the coupling agents may be used in a non-reactive, appropriate manner. It can be obtained by reacting in a suitable solvent. At this time, as the radical polymerization initiator used, for example, benzoyl peroxide, dichlorobenzoyl peroxide, 2,5-
Di (peroxybenzoate) hexyne-3,1,3-
Bis (t-butylperoxyisopropyl) benzene,
Examples include perester compounds such as t-butyl perbenzoate, azo compounds such as azobisisobutyronitrile and dimethylazobutyrate, and organic peroxides.

As the polyalkylene oxide chain-containing compound having a polymerizable double bond, for example, polyethylene glycol vinyl ether can be used, and γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl Methyldiethoxysilane and γ-methacryloxypropyltriethoxysilane can be used alone or in combination of two or more.

When the compound is synthesized by an addition reaction of isocyanate / polyol, for example, a compound having a hydroxyl group at a terminal such as polyethylene glycol is used for a compound containing a polyalkylene oxide chain, and an isocyanate such as an isocyanate-containing coupling agent is used as a coupling agent. Compounds having a group are mixed and synthesized. In this synthesis method, dibutyltin laurate, such as dibutyltin dimaleate or dioctyltin dimaleate, it is also possible to use well-known organometallic catalyst in the field of polyurethane synthesis.

As the component (C) synthesized by the above-mentioned reaction, a compound obtained by adding a coupling agent to both ends or one end of a polyalkylene oxide chain-containing compound can be obtained. And may be used as a mixture.

Among these components (C), those having an alkylene oxide chain of an ethylene oxide chain and a hydroxyl group at one end are the most preferred because they have a high anti-staining effect of the present invention, that is, a high anti-staining property and a high permeation resistance. preferable.

In the present invention, component (A), component (B),
The mixing ratio of the component (C) is not limited as long as the physical properties are satisfied.
The component (B) may be blended in an amount of 1 to 50 parts by weight , and if necessary, the component (C) in an amount of about 0.1 to 20 parts by weight with respect to 0 parts by weight.

When the amount of the component (B) is less than 1 part by weight, the effect of preventing contamination is not exerted. When the amount is more than 50 parts by weight, crack resistance is poor, so that it is not preferable. Also, (B ') the case of using a component, the resin solid content 100 parts by weight of component (A), (B') 1.0 to 50.0 parts by weight of component in terms of SiO _2, preferably 2.0-3
It is desirable to add 0.0 parts by weight because of excellent contamination resistance and crack resistance.

The term “ SiO ₂ equivalent” means that a compound having a Si—O bond such as an alkoxysilane or a silicate is completely hydrolyzed, and then calcined at 900 ° C. to form silica ( SiO ₂ ). It is expressed in minutes. In general, alkoxysilanes and silicates have a property of reacting with water to cause a hydrolysis reaction to form silanol, and to further cause a condensation reaction between silanols or silanol and alkoxy. When this reaction is performed to the ultimate, silica ( SiO ₂ ) is obtained. These reactions are

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.

When the amount of the component (C) is less than 0.1 part by weight, the effect of preventing contamination at the initial stage is not exhibited, and when the amount is more than 20 parts by weight, the crack resistance is poor, which is not preferable.

In the moisture-permeable coating composition used in the present invention, a coloring pigment is blended to form a colored (enamel) coating film. Examples of such color pigments include inorganic oxides such as titanium oxide, zinc oxide, carbon black, ferric oxide (bengala), lead chromate (molybdate orange), graphite, yellow iron oxide, ocher, ultramarine, and cobalt green. Pigments, azo pigments,
Organic pigments such as naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone can be used.

It is also possible to use extenders such as heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, barium carbonate, white carbon, and diatomaceous earth. In particular, when a matte coating film is formed, it is optimal to use white carbon or diatomaceous earth which least impairs the non-staining effect on the coating film surface.
When these inorganic substances are added to the paint, it is preferable to treat the powder surface with a coupling agent or to add the coupling agent to the paint.

In the moisture-permeable coating composition used in the present invention, various additives which can be usually added to the coating can be added to such an extent that the effects of the present invention are not affected. Such additives include plasticizers, preservatives, fungicides, anti-algal agents, defoamers, leveling agents, pigment dispersants, anti-settling agents,
Examples include an anti-sagging agent, a matting agent, and an ultraviolet absorber.

In forming the moisture-permeable coating film of the present invention, known coating methods such as brush coating, spray coating, roller coating, roll coater, and flow coater can be used as an application means.

Further, if necessary, various undercoating materials and undercoating adjustment coating materials can be used for the moisture-permeable substrate as long as the effects of the present invention are not impaired. That is, you may use the undercoat material and the base adjustment coating material which are excellent in the adhesiveness of both a moisture-permeable base material and a topcoat material, and have a moisture permeability at least equal to or more than a topcoat material.

[0047]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention. (Synthesis Example 1) Low Condensation Product of Alkyl Silicate 1 Synthesis Example Weight average molecular weight 1000, degree of condensation about 8, nonvolatile content 100
% Of methyl silicate (hereinafter, “methyl silicate A”
100 parts by weight), 71.4 parts by weight of n-hexyl alcohol and 0.03 parts by weight of dibutyltin dilaurate as a catalyst were added, mixed, and subjected to a methanol removal reaction at 75 ° C. for 8 hours to obtain an alkyl silicate. Low condensate 1
Was synthesized. The transesterification rate of this alkyl silicate low-condensate 1 was 39%, and the residual silica ratio obtained by calcining at 900 ° C. was 37.6% by weight.

(Synthesis Example 2) Synthetic example of alkyl silicate low-condensate 2 100 parts by weight of methyl silicate A, 17.6 parts by weight of n-amyl alcohol, 0.03 of dibutyltin dilaurate
By weight, the alkyl silicate low-condensate 2 was synthesized in the same manner as in Synthesis Example 1. The transesterification rate of this alkyl silicate low-condensate 2 was 11%, and the residual silica ratio was 50.3% by weight.

Synthesis Example 3 Synthesis Example of Alkoxysilane Compound Containing Polyalkylene Oxide Chain Polyethylene glycol 200 (average molecular weight 200; Wako Pure Chemical Industries, Ltd.) was placed in a reaction vessel equipped with a heating device, stirrer, reflux device, dehydration device, and thermometer. 20 parts by weight), 54.3 parts by weight of Y-9030 (manufactured by Nippon Unicar Co., Ltd.), which is an isocyanate-containing silane, and 0.05 part by weight of dibutyltin dilaurate were charged and reacted at 50 ° C. for 8 hours. Thus, a pale yellow polyethylene oxide chain-containing alkoxysilane compound was obtained. The weight average molecular weight of the alkoxysilane compound having a polyethylene oxide chain was 800 as measured by gel permeation chromatography (hereinafter referred to as GPC) in terms of polystyrene.

Using the raw materials shown in Table 1 as the overcoating materials, each of the overcoating materials was prepared in the composition shown in Table 2, and evaluated based on the following test methods.

[Table 1]

[Table 2]

1. Moisture permeability test A release paper is spread on a 300 x 300 x 2 mm glass plate, and an overcoat material is spray-coated on the glass plate so that the dry film thickness is about 30 m, dried under standard conditions for 7 days, and coated from the release paper. Was peeled off to form a free coating film. Free coating with a diameter of about 70
Six test pieces were cut out into a circular shape of mm. JISZ 0208 "Moisture-proof packaging material moisture permeability test method"
A moisture permeability test was performed in accordance with the following. The other three are JISK 540
0 8.10 A 15% by weight aqueous dispersion of carbon black was uniformly sprayed on the entire surface of the coating film at 50 ° C according to the stain resistance test.
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. Moisture permeability 40g ^/ m 2 · 24h or more: ○ 20g ^/ m 2 · 24h or more 40 g ^/ m 2 · less than 24h: △ 20g ^/ m 2 · less than 24h: × Note, the results are shown in Table 3.

[Table 3]

2. Water permeability test A 300 x 300 x 6 mm slate plate was spray-coated with an overcoat material to a dry film thickness of about 30 m and dried under standard conditions for 7 days to obtain a test specimen. Then JI
SA6909 6.13 The test was performed according to the amount of water permeation. The results are shown in Table 3.

3. Heating / cooling repetition test SK # 1000 on a mortar plate of 70 × 70 × 20 mm
A primer (epoxy resin primer, manufactured by SK Chemical Co., Ltd.) was spray-coated at a coating amount of 0.15 kg / m ^{2 and} dried under standard conditions for 8 hours. Thereafter, a top coat material was spray-coated at a coating amount of 0.3 kg / m ^{2 and} dried under standard conditions for 14 days to obtain a test specimen. Thereafter, the test was performed according to the JISA 6909 6.11 hot and cold repetition test. The evaluation was visually evaluated as ○ when there was no peeling, cracking, or swelling of the coating film, and × when there was any. The results are shown in Table 3.

(Examples 1 to 3) As shown in Table 3, in the moisture permeability test, the moisture permeability was very high even in the initial state. Since the contaminants were peeled off, the value of the moisture permeability did not decrease. These are considered to be excellent in the contaminant removing performance on the surface of the coating film, and that the internal structure of the coating film easily permeates water vapor. In addition, the water permeability is low with respect to the high moisture permeability, and it follows the shrinkage of the substrate due to repeated warming and cooling, so it has a moisture permeability and waterproof function, especially excellent moisture permeability does not decrease due to the adhesion of contaminants. It can be said that a coating film is formed.

(Comparative Example 1) Although the moisture permeability in the initial stage was sufficient, the effect of removing contaminants after treatment did not work because the tetraalkoxysilane condensate was not added, and the moisture permeability was reduced. Was.

[0056]

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. This is a method of forming a moisture-permeable coating film that does not cause a decrease in the water vapor permeability.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-136584 (JP, A) JP-A-9-206667 (JP, A) JP-A 9-137119 (JP, A) JP-A 8- 173899 (JP, A) JP-A-61-141967 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 7/24 302 B05D 5/00

Claims (6)

(57) [Claims] 1. The surface of a moisture-permeable substrate contains a condensate of tetraalkoxysilane with an average degree of condensation of 4 to 10 based on an organic synthetic resin, and the formed coating film has a moisture permeability according to JISZ 0208 of 40 g / m ^2.・ 24H or more and JIS A6909 6.13
A method for forming a moisture-permeable coating film, characterized by applying a topcoat material having a water permeability of 0.5 ml or less according to (1). 2. An average degree of condensation of tetraalkoxysilane of 4 to 4.
The method for forming a moisture-permeable coating film according to claim 1, wherein the condensate of 10 is a condensate in which an alkyl group having 1 to 3 carbon atoms and an alkyl group having 4 to 12 carbon atoms are mixed. 3. The composition according to claim 1, wherein the condensate of tetraalkoxysilane having an average degree of condensation of 4 to 10 is contained in an amount of 1 to 50 parts by weight in terms of SiO _{2 based} on 100 parts by weight of the solid content of the organic synthetic resin. 3. The method for forming a moisture-permeable coating film according to item 1. 4. An alkyl group having 1 to 3 carbon atoms and 4 to 12 carbon atoms is mixed with 100 parts by weight of the solid content of the organic synthetic resin, and the alkyl group having 4 to 12 carbon atoms is contained in the condensate. The condensate that is 5 to 50% of the alkyl group is converted to 1 in terms of SiO _2.
The method for forming a moisture-permeable coating film according to claim 2, wherein the amount is from 50 to 50 parts by weight. 5. The organic synthetic resin is a polyurethane resin.
The method for forming a moisture-permeable coating film according to claim 1. 6. An alkoxysilane compound having a polyalkylene oxide chain having 2 to 40 repeating units and having a weight-average molecular weight of 150 to 3500, is added in an amount of 0 to 100 parts by weight of the solid content of the resin. The method for forming a moisture-permeable coating film according to any one of claims 1 to 5, which is contained in an amount of 0.1 to 20 parts by weight.