JP2008127513A - Hydrophilic inorganic paint - Google Patents

Abstract

Provided is a paint having hydrophilicity which does not deteriorate a building finishing material layer in order to prevent the building finishing material layer from deteriorating on an outer wall of a building.
A paint used for forming a hydrophilic inorganic coating film on the surface of a building, wherein the paint contains a volatile organic solvent having a vapor pressure of 0.01 to 100 mmHg at 20 ° C. Features. Further, the hydrophilic inorganic coating contains a silica solution, the content of the volatile organic solvent in the hydrophilic inorganic coating is 0.1 to 30% by mass, and the vapor of the volatile organic solvent at 20 ° C. The pressure is a mixture of one having a pressure of 1 to 10 mmHg and one having a pressure of 20 to 100 mmHg.
[Selection figure] None

Description

  The present invention relates to a hydrophilic inorganic coating for forming a hydrophilic surface structure on the outer wall of a building that is directly exposed to wind and rain.

  As a conventional hydrophilic inorganic coating, a surface layer containing photocatalytic oxide particles and silica or silicone is provided on the surface of a building material base for an outer wall such as a high-rise building, and the surface according to photoexcitation of the photocatalytic oxide The surface of the layer exhibits hydrophilicity, and when the exterior wall surface is exposed to rainfall, the product is generated from combustion products such as dust and exhaust gas contained in the air, dirt that elutes from the sealant above, Hydrophobic dirt such as pollutants discharged from the exhaust port of the wall can be washed away by raindrops or used for building materials for outer walls that can be easily washed with water (for example, see Patent Document 1) .). In addition, a surface layer containing photocatalytic oxide particles is provided on the surface of the building material base for the outer wall, the surface of the layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst, and the surface of the building material for the outer wall is exposed to rainfall. Examples include those used in building materials for self-cleaning exterior walls that allow deposits and / or contaminants to be washed away by raindrops when exposed (see, for example, Patent Document 2).

  However, any of these hydrophilic inorganic paints has a problem that when the base to be coated is a glossy paint, repelling occurs and a uniform coating film is not formed.

JP 2001-49828 A (Claims 0004 to 0024) JP-A-9-228602 (Claims 0004 to 0025)

  The problem to be solved is that a uniform coating film is formed when the base to be coated is a glossy paint.

The invention according to claim 1 is characterized in that it contains a volatile organic solvent having a vapor pressure of 0.1 to 100 mmHg at 20 ° C.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, it contains a silica solution.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the content of the volatile organic solvent in the hydrophilic inorganic coating is 0.1 to 30% by mass. This is the main feature.

  The invention described in claim 4 is a mixture of the volatile organic solvent according to any one of claims 1 to 3 having a vapor pressure of 1 to 10 mmHg and 20 to 100 mmHg at 20 ° C. The most important feature is to be.

  According to invention of Claim 1, a uniform hydrophilic inorganic coating film can be formed in the outer wall surface of a building.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, a uniform hydrophilic inorganic coating film can be formed on the outer wall surface of the building.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, a more uniform hydrophilic inorganic coating film can be formed on the outer wall surface of the building.

  According to the invention described in claim 4, in addition to the effects of the invention described in claims 1 to 3, a hydrophilic inorganic coating film having no coating film defect on the outer wall surface of the building is formed with a short drying and curing time. Can be formed.

Hereinafter, embodiments embodying the present invention will be described.
The composition of the hydrophilic inorganic coating material of the present invention is, for example, as follows.
Composition example of hydrophilic inorganic coating: 100 parts by mass of isopropyl alcohol as a volatile organic solvent, 20 parts by mass of propylene glycol as a volatile organic solvent, 100 parts by mass of water as an inorganic solvent, and a silica solution 200 as a hydrophilic inorganic agent Parts by mass. The solid content of the silica solution is 25% by mass.

  Examples of the volatile organic solvent include methanol (96 mmHg, 20 ° C), ethanol (44 mmHg, 20 ° C), 1-propanol (15 mmHg, 20 ° C), isopropanol (32 mmHg, 20 ° C), butanol (5.5 mmHg, 20 ° C), alcohols such as isobutanol (8.9 mmHg, 20 ° C), ethylene glycol (0.05 mmHg, 20 ° C), polyethylene glycol (<10 Pa (= <0.075 mmHg), 20 ° C), diethylene glycol (3. 7 mmHg, 20 ° C.), polyhydric alcohols such as propylene glycol (2.6 mmHg, 20 ° C.), dichloroethyl ether (0.7 mmHg, 20 ° C.), methyl phenyl ether (2.7 mmHg, 20 ° C.), n-butyl ether ( 31mmHg, 20 ° C), Acid-n-butyl (8.4 mmHg, 20 ° C.), ethylene glycol monobutyl ether (8.5 mmHg, 20 ° C.), diethylene glycol monomethyl ether (0.2 mmHg, 20 ° C.), diethylene glycol monobutyl ether (0.02 mmHg, 20 ° C.) And ethers, esters, and polyhydric alcohol derivatives. These volatile organic solvents are required to be uniformly mixed with a silica solution described later, and are characterized by having —OH groups and —COOH groups. In the hydrophilic inorganic coating material of this invention, it is necessary to contain the volatile organic solvent whose vapor pressure in 20 degreeC is 0.01-100 mmHg among the said volatile organic solvents.

  When the vapor pressure of the volatile organic solvent at 20 ° C. is less than 0.01 mmHg, the volatilization rate of the volatile organic solvent is too slow and the silica component is unevenly distributed during the formation of the coating film to form a uniform film. Not. Conversely, when the vapor pressure of the volatile organic solvent at 20 ° C. exceeds 100 mmHg, the volatilization rate of the volatile organic solvent is too fast, and a silica solution film as a hydrophilic inorganic coating film is sufficiently formed. The solvent is volatilized before the coating, and the coating loses its fluidity, so that a uniform coating is not formed.

  The said volatile organic solvent may be used independently and may be used in mixture of 2 or more types. When used alone, it is desirable to use one having a vapor pressure of 20 to 50 mmHg. When a volatile organic solvent in this range is blended, the balance between ensuring the volatilization rate and the uniformity of the resulting coating film is excellent.

  When the volatile organic solvents are used in combination, the vapor pressure at 20 ° C. is more preferably 1-10 mmHg (= 133-1330 Pa) and 20-100 mmHg. About a thing with a high vapor pressure, Preferably it is 20-50 mmHg. When it is in this range, a uniform hydrophilic inorganic coating film can be obtained while ensuring more drying properties.

  Examples of the silica solution include aqueous dispersions of silicates such as sodium silicate and lithium silicate as colloidal silica. Also, as organosilica sol, silica methanol dispersion, isopropyl alcohol dispersion, ethylene glycol dispersion, n-propyl cellosolve dispersion, dimethylacetamide dispersion, methyl ethyl ketone dispersion, methyl isobutyl ketone dispersion, xylene / n-butanol mixed A solvent dispersion, a propylene glycol monomethyl acetate dispersion, etc. are mentioned. These may be used alone or in combination of two or more.

  The average particle diameter of the silica fine particles dispersed in the silica solution is preferably 4 to 100 nm, more preferably 6 to 50 nm, and most preferably 10 to 20 nm. When it is within this range, the bonding force between the silica fine particles becomes optimum. When the average particle diameter of the silica fine particles is less than 4 nm, the bonding force between the silica fine particles is too strong, and there is a possibility that shrinkage cracks are generated in the silica fine particle film. On the other hand, when it exceeds 100 nm, the bonding force between the silica fine particles is weak, and the silica fine particle film cannot be sufficiently formed.

  Examples of the particle shape of the silica fine particles include a spherical shape, a pearl necklace shape, a needle shape, and a rod shape. Of these, a spherical shape is preferable. Since the silica fine particles are spherical, when the silica fine particles are dried to form a dry gel, the particles can have a close-packed structure, so that the strength of the silica fine particle film can be improved.

  The silica fine particle film formed on the outer wall surface of the building by the silica fine particles needs to have a thickness of 2 to 150 μm, more preferably 5 to 100 μm, and most preferably 30 to 50 μm. preferable. When it exists in this range, sufficient hydrophilicity can be provided to the outer wall surface of a building. When the thickness of the silica fine particles formed on the outer wall surface of the building is less than 2 μm, the silica fine particle film is too thin and vulnerable to external impacts, so that surface cracks are likely to occur. On the other hand, if it exceeds 150 μm, the light transmittance of the silica fine particle film is lowered, so that the color and gloss of the building finishing material may be suppressed and the designability may be lowered. Further, when the thickness of the silica fine particle film is 5 μm or more, the silica fine particle film remains even if the silica fine particle film flows out due to the aging wind and rain, so that the durability is excellent.

  The silica fine particle film preferably has a crystallized film structure. Since the silica fine particle film has a crystallized film structure, it is possible to suppress the outflow of the silica fine particle film surface due to aged wind and rain as compared with an amorphous state.

  For the setting of the silica fine particle thickness, the actual required amount per square meter is calculated from the mass of the silica fine particles per square meter, the specific gravity of the silica fine particles, and the solid content concentration of the hydrophilic inorganic paint when the planned thickness is obtained. After that, it is calculated in consideration of scattering loss due to spray painting. The scattering loss is expected to be 20% for airless spray and 40% for air spray, and the calculated coating amount is 80% for airless spray and 60% for air spray.

  The photocatalytic oxide particles described in the description of the background art are oxide particles in which excitation of electrons in the valence band is caused by light irradiation. Specifically, typical metal oxides such as titanium oxide and zinc oxide are oxidized. Say things. In the present invention, it is necessary not to contain photocatalytic oxide particles in the outer wall structure. By not containing the photocatalytic oxide particles, organic substances such as building finishing materials as a base are not decomposed.

Formation of the outer wall structure of the building configured as described above is performed as follows. First, a synthetic resin paint as a building finishing material is painted on the surface of the outer wall of the building. After the synthetic resin paint is dried to form a coating film, a hydrophilic inorganic paint is applied with an airless spray at an average coating amount of 50 g / m ² . This average coating amount excludes the scattering loss (20%) due to airless spray coating.

  The hydrophilic inorganic paint is obtained by diluting 100 parts by mass of an aqueous colloidal silica dispersion (silica content 25% by mass) having an average particle diameter of 15 nm with 48 parts by mass of isopropyl alcohol and 50 parts by mass of propylene glycol. is there.

  When the hydrophilic inorganic paint is alkaline, it is preferable to add an indicator that is colored in the alkaline region (pH of more than 8) to the alcohols. By adding the indicator, the solution can be discolored by mixing the two, so that it is possible to visually confirm that the hydrophilic inorganic paint and alcohol are mixed, and the construction remains unmixed. Can be prevented. Moreover, since it is colored, construction / non-construction can be easily discriminate | determined visually, Therefore Forgetting to paint can be prevented.

  The indicator is preferably colorless or pale in an acidic region (less than pH 6) and a neutral region (pH 6-8). Because the indicator is colorless in the acidic region and neutral region, it is neutralized by carbon dioxide gas or acid rain in the atmosphere after construction, and the color gradually fades, so the design of the building finishing material after construction is completed Does not affect sex.

  The content of the indicator with respect to the alcohol is preferably 0.001 to 5.0% by mass, more preferably 0.005 to 1.0% by mass, and most preferably 0.01 to 0.5% by mass. %. When it is in this range, an appropriate color can be shown in the alkaline region, so that it does not affect the design of the building finishing material. When the content of the indicator with respect to the alcohol is less than 0.001% by mass, the coloring is not sufficient, which may cause forgetting to mix or forget to paint. Conversely, if it exceeds 5.0% by mass, the coloration is too strong and neutralization with carbon dioxide gas or the like does not proceed to a considerable extent, so that the surface of the building finishing material is colored over a long period of time without becoming colorless or pale. , There is a risk of harming the design of the building finishing material.

  Among the indicators, those that are colorless or light in the acidic region and neutral region include, for example, lactone indicators such as phenolphthalein and thymolphthalein, sultone indicators such as bromothymol blue and phenol red, and alizarin yellow. And diazo indicators, thealvidin, and the like. Of these, lactone indicators are preferably used, and phenolphthalein or thymolphthalein is more preferably used. By using a lactone-based indicator, it is colorless in the acidic region and neutral region, so it does not affect the design of the building finishing material.

  When the hydrophilic inorganic paint containing the lactone-based indicator is neutralized by carbon dioxide gas or the like from the alkaline region immediately after the construction to the neutral region or further the acidic region, the conjugated benzene ring The double bond between carbon and carbon becomes a single bond, and one phenol that was quinone type closes to become a lactone ring. The lactone ring is not conjugated like the benzene ring and is colorless because it absorbs only ultraviolet rays with a short wavelength. Thus, when several hours to 10 days have passed since the construction, the original design of the building finishing material is exhibited.

  It is preferable to add a surfactant to the hydrophilic inorganic paint. By adding the surfactant, a uniform silica fine particle film can be formed even if the surface of the building finishing material is non-hydrophilic.

  Examples of the surfactant include sodium lauryl sulfate, triethanolamine lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, dodecylbenzenesulfonic acid, sodium dialkylsulfosuccinate, sodium alkyldiphenyl ether disulfonate, styrene maleic acid resin half ester, polycarboxylic acid Acid ammonium salt etc. are mentioned. Among these, it is preferable to use polycarboxylic acid ammonium salt. By using the polycarboxylic acid ammonium salt, it is possible to achieve good adhesion even if the surface of the building finishing material is non-hydrophilic.

  The blending amount of the surfactant in the hydrophilic inorganic coating is preferably 1.0% by mass or less. If it exceeds 1.0% by mass, the water resistance of the hydrophilic inorganic coating film is lowered, and if it is more than 5% by mass, film formation is poor.

  It is preferable to form a silane coupling agent film between the building finishing material and the silica fine particle film. By forming the silane coupling agent film, the building finishing material and the silica fine particle film can be firmly adhered to each other.

  The silane coupling agent film is a thin film having an ethoxy group or a methoxy group that imparts a silanol group by hydrolysis at one end of the molecule and an organic functional group such as an amino group or glycidyl group at the other end. Say things. The silane coupling agent film serves as an adhesive in which silanol groups are bonded to the silica fine particle film and organic functional groups are bonded to the building finishing material.

  The building finishing material is a building material that is constructed to give a design such as color and shape to a building. For example, a synthetic resin blend paint defined in JIS K 5516, JIS K 5572 Phthalic acid resin enamel, acrylic resin varnish specified in JIS K 5653, acrylic resin enamel specified in JIS K 5654, glossy synthetic resin emulsion paint specified in JIS K 5660, and JIS K 5663 Specified synthetic resin emulsion paint, variegated pattern paint specified in JIS K 5667, Synthetic resin emulsion pattern paint specified in JIS K 5668, Vinyl chloride resin varnish specified in JIS K 5581, JIS K Vinyl chloride specified in 5582 Nyl resin enamel, acrylic resin non-aqueous dispersion paint defined in JIS K 5670, architectural polyurethane resin paint defined in JIS K 5656, and polyurethane resin paint for steel structures defined in JIS K 5657 , Fluorine resin paints for construction specified in JIS K 5658, Fluorine resin paints for steel structures specified in JIS K 5659, Thin finish coating materials specified in JIS A 6909, Multi-layer finish coating materials And finish coating materials for flexible shape repair.

  The surface of the building finishing material is preferably hydrophilic. Since the surface of the building finishing material is hydrophilic, the adhesion to the silica fine particles is excellent.

  When the surface of the building finishing material is hydrophilic, the contact angle value with respect to water is preferably 50 ° or less, more preferably 40 ° or less, and most preferably 30 ° or less. When in this range, the adhesiveness to silica fine particles that are also hydrophilic is excellent. When the contact angle with water on the surface of the building finishing material exceeds 50 °, the adhesion with the silica fine particles may not be sufficient.

Moreover, in the building finishing material which cannot measure the value of the contact angle with water, it is preferable that it is 0.1 ml or more in the water permeability test B method prescribed | regulated to JISA6909. In addition, the numerical value for the upper limit is not provided because it becomes impossible to measure, but it shall satisfy the quality specified in JIS for other items.

  The addition amount of the organic substance is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and most preferably 5 parts by mass or less, with respect to 100 parts by mass of the silica fine particles in the silica solution blended with the hydrophilic inorganic paint. When in this range, the silica fine particle film is excellent in durability. When the addition amount of the organic substance with respect to 100 parts by mass of the silica fine particles exceeds 20 parts by mass, the originally hydrophilic silica fine particles and the originally hydrophobic organic substance repel each other, There is a risk of hindering fixation. When the amount exceeds 10 parts by mass, generally, the surface of the building finishing material is often organic, so the organic matter in the hydrophilic inorganic coating collects on the surface of the building finishing material and causes the silica fine particle film to “float”. There is a fear.

  The silica fine particle content in the hydrophilic inorganic coating is preferably 0.5 to 20% by mass, more preferably 0.5 to 15% by mass, and most preferably 1 to 10% by mass. When it is within this range, it is optimal for forming a silica fine particle film. When the silica content in the hydrophilic inorganic coating is less than 0.5% by mass, a large number of coatings are necessary to ensure a sufficient thickness of the silica fine particle film, and the construction is inferior. On the other hand, when it exceeds 20% by mass, it is difficult to obtain a uniform silica fine particle film because the amount applied at once is too large.

  The application of the hydrophilic inorganic paint is not limited to the airless spray, and any apparatus used for the usual paint application such as air spray, roller, brush, etc. can be used. Among these, it is preferable to apply by spraying such as airless spray or air spray. By applying by spraying, a uniform silica fine particle film can be formed.

  The hydrophilic inorganic paint is preferably applied in two or more times without securing a predetermined film thickness by one application. By dividing and coating two or more times, a uniform silica fine particle film can be obtained, so that the occurrence of iris and unevenness can be suppressed.

  The hydrophilic inorganic paint applied in the above manner fixes individual silica fine particles by drying to form a uniform silica fine particle film. The contact angle of the silica fine particle film with respect to water is 0 ° to 20 ° regardless of the presence or absence of light irradiation.

  The outer wall is contaminated when contaminants such as dust floating in the atmosphere adhere to the outer wall of the building thus formed. Since the outer wall of the building is given hydrophilicity by the silica fine particle film, raindrops permeate the interface between the pollutant and the outer wall, lift the pollutant, and flow down from the outer wall surface of the building by gravity. Contamination of the outer wall can be suppressed.

  Further, since the silica fine particle film itself does not decompose the organic matter contained in the building finishing material as a base, it does not hinder the durability of the building finishing material over a long period of time.

This embodiment can exhibit the following effects.
-When the average particle diameter of the silica fine particles is 4 to 100 nm, the bonding force between the silica fine particles is optimized.

  -Since the particle shape of the silica fine particles is spherical, when the silica fine particles are dried to form a dry gel, the particles can take a close-packed structure, thereby improving the strength of the silica fine particle film. be able to.

  -Sufficient hydrophilicity can be provided to the outer wall surface of a building by the thickness of the silica fine particle film | membrane formed on the outer wall surface of the said silica fine particle building being 2-150 micrometers.

  ・ When diluting the hydrophilic inorganic coating, use the surface tension of the hydrophilic inorganic coating by diluting with alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol. Therefore, it can apply | coat thinly and uniformly on the surface of a building finishing material.

  -By adding a surfactant to the hydrophilic inorganic paint, a uniform silica fine particle film can be formed even if the surface of the building finishing material is non-hydrophilic.

  -By using polycarboxylic acid ammonium salt as the surfactant, the surface of the building finishing material can be satisfactorily adhered even if it is non-hydrophilic.

  -By the contact angle with respect to the water of the said building finishing material surface being 50 degrees or less, it is excellent in adhesiveness with the silica fine particle which is also hydrophilic.

  -The durability of a silica fine particle film | membrane is excellent because the addition amount of the organic substance with respect to 100 mass parts of silica fine particles in the said hydrophilic inorganic coating material is 20 mass parts or less.

  -A silica fine particle film | membrane is optimally formed because the silica content rate in the said hydrophilic inorganic coating material is 5-40 mass%.

  A uniform silica fine particle film can be formed by applying the hydrophilic inorganic paint by spraying such as airless spray or air spray.

  -In the construction of the hydrophilic inorganic paint, a uniform silica fine particle film can be obtained by dividing and coating two or more times without securing a predetermined film thickness by a single coating. Unevenness can be suppressed

In addition, the said embodiment of this invention can also be changed and comprised as follows.
In the above-described embodiment, the silica fine particle film is formed at the construction site. However, the silica fine particle film may be formed in advance by painting the silica fine particles on the outer wall material in a factory or the like.

  -In the said embodiment, although the silica fine particle film | membrane by a hydrophilic inorganic coating material was formed on the building finishing material, you may form directly on the surface of inorganic substances, such as concrete.

-In the said embodiment, although the hydrophilic inorganic coating material was dried under external temperature and the silica fine particle film | membrane was formed, you may form by heat drying.
When comprised in this way, the time which drying requires can be shortened.

-Although alcohol is used in the said embodiment, you may dilute and use this alcohol with water.
When comprised in this way, the danger of the ignition of alcohol can be reduced.

  In the above-described embodiment, the alcohol contains an indicator. However, the hydrophilic inorganic paint is adjusted to an optimum pH range, or by selecting the optimum indicator for the pH of the hydrophilic inorganic paint, You may make it contain in an inorganic coating material.

Next, technical ideas other than the invention described in the claims ascertained from the embodiment will be described together with their effects.
(1) A method for forming an outer wall of a building, wherein a silica fine particle film is formed on the surface of a hydrophilic building finishing material.
When comprised in this way, it is excellent in adhesiveness with a silica fine particle.

(2) A method for forming a building outer wall, comprising forming a silica fine particle film on the surface of a building finishing material having a contact angle with water of 50 ° or less.
When comprised in this way, it is excellent in adhesiveness with a silica fine particle.

Hereinafter, the remarkable effect of the present invention as compared with the prior art will be described by comparative tests on the examples.

  In the test, a test body in which a white acrylic resin paint was applied to a 70 × 150 × 2.3 mm slate plate was used as a standard base material, and paints of Examples and Comparative Examples having the formulations shown in Table 1 below were spray-coated. The surface state after coating the paint was observed with a microscope (200 times), and the film forming state on the substrate surface was evaluated. The evaluation results are shown in Table 2 below. In the table, real 1 represents Example 1, real 2 represents Example 2, and ratio 1 represents Comparative Example 1. The same abbreviations are used in Tables 2 to 5 below.

  Next, the specimen was exposed outdoors at a horizontal angle of 30 degrees for 6 months, and the deterioration state of the coating film was visually observed, and the L values in the Lab color system before and after the exposure were compared. The L value of the standard specimen before exposure was 99.7. The evaluation results are shown in Table 3 below.

  Furthermore, in accordance with PWTM-3-2000pr Contamination Material Evaluation Promotion Test Method (Draft) for Civil Engineering Structures, Part 2 Antifouling Material Evaluation Promotion Test Method 2 (2 is Roman numeral) (for tunnel) A contamination test was conducted. The results of this accelerated contamination test are shown in Table 4 below.

  In the accelerated contamination test, an acrylic resin paint is applied to an aluminum plate of 200 × 120 × 1 mm, and the paint of the example or comparative example is sprayed on the next day, and after a curing period of 2 weeks, as a pretreatment The specimen was placed at a temperature of 50 ° C. ± 1 ° C. and a relative humidity of 95% or more for 24 hours and dried at a temperature of 20 ° C. ± 1 ° C. and a relative humidity of 65% ± 5% for 3 days. One of the multiple test specimens is used as a back plate. As the soiling substance, 2.3% by mass of carbon black (particle size: 0.002 to 0.28 μm), 9.3% by mass of carbon black (12 kinds of test dust, JIS Z8901), yellow ocher (natural pigments) 62.8% by mass of ocher), 20.9% by mass of sintered Kanto loam (8 types of test dust, JIS Z8901), and 4.7% by mass of silica powder (3 types of test dust, JIS Z8901) Used after mixing and stirring in a magnetic pot. Sprinkle dirt material until the specimen is no longer visible, and tap the back of the specimen with a spoon to remove the dirt. After the soiling substance is sprinkled and removed 5 times, the gauze is changed and washed under running water until the soiling substance does not fall to such an extent that the coating film is not damaged. After washing, the specimen was dried, the L value of the specimen and the backing plate was measured with a color difference meter, and ΔL, which is the difference, was obtained by calculation.

  In Table 1, IPA refers to isopropanol, PG refers to propylene glycol, and EG refers to ethylene glycol. As the silica solution, a sodium silicate aqueous dispersion as colloidal silica having a silica content of 25% by mass was used. The vapor pressure at 20 ° C. of each volatile organic solvent is 32 mmHg for IPA, 2.6 mmHg for PG, 0.05 mmHg for EG, 170 mmHg for methyl acetate, and 0.0025 mmHg for glycerin. As the indicator, a phenolphthalein solution (0.1 g phenolphthalein dissolved in 100 g IPA) was used. A polycarboxylic acid ammonium salt was used as the surfactant.

  Next, a test body in which an exterior synthetic resin emulsion-based finish coating material is applied as a standard base material among the thickening finish coating materials specified in JIS A6909 on a slate plate of 70 × 150 × 2.3 mm is used as a standard base material. The paints of Examples 1, 4 and Comparative Example 1 were spray coated. The water permeability of the water permeability test on the standard substrate was 0.1 ml. Cured for one week in a constant temperature room at 20 ° C and 65% RH. JIS K5600-5-6 “Part 5: Mechanical properties of coating film” The adhesion test specified in “Crosscut method” was conducted. In the test, cuts to form a grid with 5 mm intervals on the surface of the coating were applied to the surface of the substrate with a cutter knife, and then a transparent cellophane tape was applied, rubbed firmly with the fingertips, peeled off, and peeled off. The area of the film is evaluated. The test results are shown in Table 5 below.

  Classification 0 as the evaluation result is that the edges of the cut are smooth and there is no peeling to the eyes of any lattice. In category 1, there is a small peeling of the coating film at the intersection of the cuts, and it is clearly not more than 5% that it is affected at the crosscut part. In category 2, the coating is peeled along the edge of the cut and / or at the intersection. The cross-cut portion is clearly affected by more than 5% but not more than 15%. In the following, as the classification 5, those in which partial or full peeling occurs and the peeling exceeds 65% are classified.

Claims (4)

A paint used for forming a hydrophilic inorganic coating film on the surface of a building, wherein the paint contains a volatile organic solvent having a vapor pressure of 0.01 to 100 mmHg at 20 ° C. Inorganic paint. The hydrophilic inorganic paint according to claim 1, wherein the hydrophilic inorganic paint contains a silica solution. The hydrophilic inorganic paint according to claim 1 or 2, wherein the content of the volatile organic solvent in the hydrophilic inorganic paint is 0.1 to 30% by mass. The hydrophilic inorganic paint according to any one of claims 1 to 3, wherein the volatile organic solvent is a mixture of one having a vapor pressure of 1 to 10 mmHg and 20 to 100 mmHg at 20 ° C. .