JP2005226046A - Coating material composition for preventing surface of construction from being stained - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coating material composition for preventing a surface of a construction from being stained, which necessitates no troublesome acid-treatment, uses no catalyst which gives damage to the surface of the construction and causes application restriction, immediately effects on stain resistance after being applied, has excellent storage stability, drying properties, adhesion to a cured coating film and transparency, and is capable of forming an excellent stain-resistant coating film onto the surface of the construction. <P>SOLUTION: This coating material composition for preventing the surface of the construction, is prepared by the followings. An organosilicate expressed by the formula (1): HxSi(OR)y (in the formula, R is a 1-3C alkyl group; (x) and (y) are each an integer of 0-4 wherein the total of x+y is 4) is prepared. After 100 pts.wt. of the organosilicate (in terms of SiO2 of an Si atom) is hydrolyzed in the presence of a water/solvent mixture composed of 60-50,000 pts.wt. of water and 60-50,000 pts.wt. of a solvent compatible with water and the organosilicate each other, 0.01-1 pts.wt. of an aluminum alkoxide in terms of Al, is added to the resulting hydrolyzed product on the basis of 100 pts.wt. of the organosilicate used as a raw material (in terms of SiO2 of the Si atom). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention may be applied to a surface of a structure formed of, for example, metal, ceramic, glass, plastic, concrete, stone, wood, a combination thereof, or other materials. Smoke and exhaust gases such as windows and guardrails, highway bridge girders, bridges, overpasses, road signs, park facilities, other structures, automobiles, aircraft, rail cars, ships, and other vehicles The present invention relates to a coating composition for preventing contamination of a structure surface, which is applied to the surface of an outdoor structure exposed to a cause of contamination such as, and which can prevent the surface of the structure from being contaminated by the cause of contamination as much as possible. .

  Contaminating substances such as carbon and organic matter are likely to adhere to the surface of the structure, especially outdoor structures that are constantly exposed to the cause of contamination such as smoke and exhaust gas. If they adhere to the surface, these pollutants flow on the surface of the structure during rain and appear as black streaks (rain streaks), which significantly impairs the appearance of the structure surface.

  Therefore, conventionally, as a means for preventing such contamination of the structure surface as much as possible, for example, a fluorine-based coating agent in which an alkyl silicate or a condensate thereof is added to a hydrophobic fluororesin paint has been proposed. (Japanese Patent Laid-Open Nos. 08-120, 211, 08-120, 212, 08-176, 304, etc.). However, in such a fluorine-based coating agent, the effect of preventing contamination is improved to some extent by adding alkyl silicate or its condensate, but the surface exhibits hydrophilicity due to the highly hydrophobic fluororesin coating material. It takes a long time to finish, the antifouling resistance is low at the initial stage after the coating film is formed, and rain streaks may adhere at the very initial stage, and the contamination of the structure surface cannot be completely prevented. There is.

  In addition, recently, for the purpose of low contamination and non-contamination of the structure surface, (a) the hydrophilic coating has a lower electrical resistance and is less likely to be charged. Difficult, (b) Even if dirt or dirt adheres, it does not fit well with the paint film, so it is difficult to enter the paint film. For this reason, it has been found that it is more effective to make the surface of the structure more hydrophilic (to make it hydrophilic) (February 10, 1995, Monthly Building Materials News, pages 18-19) ).

  Therefore, as a method of obtaining such a hydrophilic coating film, first, an undercoat paint is applied, and then an organosilicate and / or a condensate thereof is blended with an organosilicon curable solvent-based paint, and an acid treatment is performed. A method for obtaining a hydrophilic cured coating film by applying a top coating having a contact angle with water of 70 ° or less on the surface of the subsequent cured coating film and then curing by acid treatment has been proposed (Japanese Patent Laid-Open No. 07-136,584). Gazette and patent 2,869,443). However, in this method, it is necessary to perform an acid treatment after the top coating is applied, and there is a problem that the number of treatment steps increases and the cost increases.

  Alternatively, the organosilicate is hydrolyzed in the presence of an acid catalyst using 3-70 parts by weight of water with respect to 100 parts by weight of SiO 2 in terms of SiO 2 in the organosilicate. It has been proposed to apply a decomposition reaction product to the surface of a structure (Japanese Patent Laid-Open No. 07-136,583). However, in this method, since less water is used for hydrolysis, alkoxy groups remain in the hydrolysis reaction product, and the remaining alkoxy groups are hydrolyzed with moisture in the air as time passes after coating. Even if hydrophilicity may be obtained, there is a problem that hydrophilicity cannot be obtained for a while after coating, contamination proceeds during that time, and as a result, a sufficient antifouling effect cannot be obtained.

Furthermore, as another method, a method of blending an organosilicate and / or a condensate thereof with an acidic surfactant or a boron compound (Japanese Patent Laid-Open No. 2000-309,749), an organosilicate such as hydrochloric acid or acetic acid is used. Acid catalysts, alkali catalysts such as sodium hydroxide, organotin compounds such as dibutyltin laurate, organoaluminum compounds such as aluminum tris (acetylacetonate), organotitanium compounds such as titanium tetrakis (acetylacetonate), zirconium tetrakis (acetyl) A method of blending a catalyst such as an organometallic compound other than an organosilicate such as an organozirconium compound such as acetonate) or a metal alkoxide compound (Japanese Patent Laid-Open No. 2000-327,996), using an acid catalyst such as hydrochloric acid or acetic acid as an organosilicate Diluted with water after hydrolysis A method for adjusting the moisture content using a catalyst (Japanese Patent Laid-Open No. 2002-173,642) and the like have been proposed. The kind and material of the object are significantly restricted.
JP 08-120,211 Japanese Patent Laid-Open No. 08-120,212 Japanese Unexamined Patent Publication No. 08-176,304 Japanese Patent Laid-Open No. 07-136,584 Japanese Patent No. 2,869,443 Japanese Patent Laid-Open No. 07-136,583 JP 2000-309,749 A JP 2000-327,996 Japanese Patent Laid-Open No. 2002-173,642 February 10, 1995, Monthly Building Materials News, pages 18-19

  Therefore, the present inventors do not require troublesome acid treatment, and without using a catalyst that causes surface damage and application restrictions of the structure, an excellent stain-resistant coating film on the surface of the structure. As a result of intensive investigations on the anti-staining coating composition that can be formed, a specific organosilicate is hydrolyzed with a water / solvent mixture, and an aluminum alkoxide is used as a stabilizer in the obtained hydrolysis reaction product. By containing it in a proportion, it has hydrophilicity immediately after coating, exhibits excellent antifouling resistance, has excellent storage stability and drying properties, and is excellent in handleability, and further cured. The present invention was completed by finding that a coating film having excellent adhesion and transparency to the coating film, good appearance, and no damage to the surface of the structure and no application restrictions was formed.

  Therefore, the object of the present invention is that it does not require troublesome acid treatment, and without using a catalyst that causes damage to the surface of the structure or application restrictions, and is excellent in antifouling resistance immediately after application and storage stability. An object of the present invention is to provide a stain-preventing coating composition that can form a stain-resistant coating film having excellent properties, drying properties, adhesion to a cured coating film, and transparency, and an excellent surface.

That is, the present invention provides the following general formula (1)
HxSi (OR) y (1)
(However, R shows a C1-C3 alkyl group, x and y are the integers in any one of 0-4, and the sum x + y of both shows the integer which is 4, y is 2-4. R may be the same or different from each other.) 100 parts by weight of the organosilicate represented by (in terms of SiO2 of Si atoms) is soluble in 60 to 50,000 parts by weight of water and the above organosilicate and water. In the hydrolysis reaction product obtained by hydrolysis in the presence of water / solvent with 60 to 50,000 parts by weight of the solvent, 100 parts by weight of organosilicate used as a raw material (in terms of SiO2 of Si atoms) A coating composition for preventing contamination of a structure surface, which contains 0.01 to 1 part by weight of aluminum alkoxide as Al.

  In the present invention, examples of the organosilicate represented by the general formula (1) include a methyl group, an ethyl group, an n-propyl group, and an iso-propyl group as specific examples of the alkyl group R having 1 to 3 carbon atoms. Can be mentioned. Among these alkyl groups R, a methyl group or an ethyl group is preferable in order to facilitate hydrolysis without a catalyst using a water / solvent mixture. Specific examples of the organosilicate having a methyl group or ethyl group as the alkyl group R include tetramethyl silicate, trimethyl silicate, dimethyl silicate, monomethyl silicate, tetraethyl silicate, triethyl silicate, diethyl silicate, and monoethyl silicate. Particularly preferred are tetramethyl silicate, tetraethyl silicate, and triethyl silicate. The above organosilicate can be used alone or as a mixture of two or more.

  In the present invention, the organosilicate is not used as an oligomer but as a monomer. This is not only excellent in terms of hydrolysis rate, work efficiency, economy, etc., but also has excellent affinity for the surface of the structure, and the resulting coating film has hydrophilicity. Is even better about.

  The amount of water used for hydrolyzing the above-mentioned organosilicate is 60 parts by weight or more and 50 parts by weight or more based on 100 parts by weight of organosilicate (converted to SiO2 of Si atoms) when Si atoms in the organosilicate are converted to SiO2. Is less than 1,000 parts by weight, preferably 100 parts by weight or more and 20,000 parts by weight or less. When the amount of water used is less than 60 parts by weight, SiO 2 is contained in the resulting anti-staining coating composition. The amount becomes too large, and it is easy to gel during storage and lacks storage stability. Also, the alkoxy group remains and it is difficult to obtain the desired hydrophilicity, so that the antifouling effect is lowered. If it exceeds, the content of SiO2 in the resulting anti-contamination coating composition will be too low, and the anti-contamination function will be difficult to develop, resulting in a decrease in anti-contamination effect.

  The water used for the hydrolysis of the organosilicate is not particularly limited and may be tap water. For example, when used for applications such as electrical materials and electronic materials, it is preferably deionized water. In the case of use, it is preferable to select appropriately according to the purpose of use and use such as using ultrapure water.

  In the present invention, the hydrolysis reaction of the organosilicate is carried out in the presence of water / solvent in which the organosilicate and water and a solvent that are mutually soluble are added to the reaction system, and the water and solvent are present in a homogeneous system. The solvent used for this purpose is not particularly limited as long as it is mutually soluble with the organosilicate and water, but considering that it volatilizes when a coating film is formed after coating, for example, alcohols, especially Those having high volatility such as methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol and the like which are not likely to cause pollution are desirable. These solvents can be used singly or as a mixture of two or more if necessary, and may be introduced into the reaction system separately from water, or mixed with water in advance. It may be introduced into the reaction system.

  The amount of the solvent used is 60 to 50,000 parts by weight, preferably 100 parts by weight based on 100 parts by weight of the organosilicate (converted to SiO2 of Si atoms) in terms of Si2 in the organosilicate. The amount is preferably 20,000 parts by weight or more and 20,000 parts by weight or less. If the water content is less than 60 parts by weight, the content of SiO 2 in the resulting anti-staining coating composition is excessively increased and gelation is likely to occur during storage. Insufficient storage stability, and it is difficult to obtain the desired hydrophilicity due to the remaining alkoxy group, resulting in a low anti-staining effect. On the other hand, when the amount exceeds 50,000 parts by weight, the resulting anti-staining coating composition is obtained. The content of SiO2 in the inside becomes too low, making it difficult for the pollution prevention function to appear. As a result, the pollution prevention effect is reduced, and there are cases where it falls under dangerous goods under the Fire Service Law, causing problems in handling. The

  In the present invention, 0.01 to 1 part by weight of aluminum alkoxide as Al as a stabilizer is added to a hydrolysis reaction product obtained by hydrolyzing an organosilicate in the presence of water and a solvent. As the aluminum alkoxide used for this purpose, any aluminum alkoxide may be used as long as it is added to the hydrolysis reaction product and dissolves easily. Preferably, the aluminum content in the aluminum alkoxide is 12% by weight or more, more preferably 13% by weight. It should be at least%. If the aluminum content in the aluminum alkoxide is lower than 12% by weight, it is necessary to add such a large amount, which is uneconomical, and if the aluminum alkoxide has a higher alkoxy group, the solubility in water becomes worse. Arise.

  Specific examples of such aluminum alkoxide include, for example, aluminum trimethoxide, aluminum triethoxide, aluminum tri-n-propoxide, aluminum triiso-propoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum Triter-butoxide and the like can be mentioned, and these can be used alone or as a mixture of two or more.

  The amount of aluminum alkoxide used is 0.01 parts by weight or more and 1 part by weight with respect to 100 parts by weight of organosilicate (converted to SiO 2 of Si atoms) by converting Si atoms in the organosilicate used as a raw material into SiO 2. In the following, it is preferably 0.03 parts by weight or more and 0.1 parts by weight or less, and if it is less than 0.01 parts by weight, the storage stability of the resulting antifouling coating composition is lowered and increased. When a phenomenon such as viscosity increase or white turbidity occurs, and the amount exceeds 1 part by weight, the aluminum content becomes too high, and the adhesion and transparency of the coating film, and further the low contamination property is lowered.

  Note that the use of a relatively large amount of an organoaluminum compound other than the above aluminum alkoxide as a stabilizer is insoluble in solvents such as water and alcohols, or generates an acid by dissolving in water such as aluminum nitrate. Or aluminum tris (acetylacetonate), etc., which may remain in the coating film, but it is relatively toxic, as well as organic aluminum such as aluminum tris (acetylacetonate). The compound generally has an aluminum content of 10% by weight or less, and there is a problem in terms of practical cost.

  Further, in the present invention, it is a feature that a catalyst that causes damage to the surface of the structure and application restrictions is not used. However, a hydrolysis catalyst is substantially contained in the coating composition for preventing contamination of the present invention. If it is not included, it should not contain any organoaluminum compounds or other compounds other than aluminum alkoxides that have a catalytic action on the hydrolysis reaction of organosilicates, as long as they do not cause damage to the surface of the structure or application restrictions. The range is usually 0.001 part by weight or less, preferably 0.0001 part by weight or less, more preferably 0.00001 part by weight or less based on 100 parts by weight of organosilicate (in terms of SiO2 of Si atoms). Is good. If the content of the compound having a catalytic action exceeds 0.001 part by weight, there may be a problem of surface damage of the structure or a problem of application restriction.

  The manufacturing process of the antifouling coating composition of the present invention includes a hydrolysis process in which an organosilicate is hydrolyzed in the presence of water and a solvent to prepare a hydrolysis reaction product, and the hydrolysis obtained in this hydrolysis process. And a stabilization step of adding aluminum alkoxide in a predetermined ratio to the reaction product. The hydrolysis reaction in the hydrolysis step may be performed at room temperature or at a temperature of 100 ° C. or lower, preferably at a temperature of 30 ° C. or higher and 90 ° C. or lower. The time varies depending on the number of carbon atoms of the alkyl group R in the general formula (1) and the reaction temperature, and when it is kept at a high temperature for a long time, the silica precipitates and becomes cloudy or gelation occurs. For example, when the number of carbon atoms of the alkyl group R in the general formula (1) is 1, the reaction temperature is 30 ° C. within 12 hours, preferably within 5 hours. It may be within 1 hour at 90 ° C., preferably within 10 minutes.

  In the present invention, a high-viscosity solvent such as ethylene glycol or propylene glycol is added to the composition for the purpose of adjusting the viscosity according to the purpose or use of the anti-staining coating composition. For the purpose of adjusting the drying speed, a high boiling point solvent such as methyl isobutyl ketone or xylene may be added. Further, a pigment such as zinc chloride, an antibacterial agent such as silver, a soil decomposing agent such as titanium oxide, a surfactant and the like can be added. This is because the silica is silicic acid in the coating composition of the present invention. This is presumably due to the fact that this silicic acid is stabilized by aluminum and does not undergo major changes such as gelation even when other substances are added.

  The anti-fouling coating composition of the present invention includes, for example, various structures formed of inorganic materials such as concrete, fiber reinforced concrete, slate, glass, ceramic, acrylic resin, fluorine resin, polyurethane resin, and polyester resin. Structures made of organic materials such as films, sheets, other resin moldings, rubber moldings molded with synthetic rubber or natural rubber, molded with synthetic resins such as polycarbonate resin, vinyl chloride resin, polyethylene resin And structures formed of metal materials such as aluminum, iron, stainless steel, galvanized steel, and steel, structures formed of organic-inorganic composite materials such as fiber reinforced plastic (FRP), and combinations of these structures The surface of each structure, such as structures formed by laminating or stacking, is coated with fluororesin paint or polyurethane resin. Can be applied acrylic resin paint, Ponoesuteru resin coating, a structure having a coating layer formed by applying a coating, such as aqueous resin coating material or the like, on the surface of the very many types of structures.

In applying the anti-staining coating composition of the present invention to the structure surface, it may be applied directly to the structure surface, or after the surface of the structure has been previously treated with a primer or the like. Alternatively, it may be applied after undercoating.
Application of the anti-staining coating composition of the present invention to the surface of the structure is, for example, means such as brush coating, roller coating, spray coating, flow coater, gravure coater, spin coater, etc., depending on the type of structure. In addition, drying after coating may be performed at room temperature or by heat drying.

  The coating composition for preventing contamination of the structure surface of the present invention includes, for example, a building outer panel, a tent, a waterproof sheet, a windproof sheet, a building sheet, a roofing material, a skylight, a concrete wall, a water storage tank, a tank, a shutter, Outdoor building members such as sashes, handrails for buildings, building exterior walls, guardrails, pedestrian bridges, exterior panels, translucent plates, soundproof walls, signs, highway side walls, tunnel walls, railway viaducts, road members such as bridges, Starting with outdoor structures such as outdoor objects such as park objects, various indoor building components such as partitions, handrails for indoor stairs, pillars, window frames, door frames, indoor wall materials, desks, chests, By applying it to surfaces where various indoor structures such as electric appliances and other indoor structures are prone to contamination, dirt temporarily attached to outdoor structures is washed away by rain, and indoor structures Temporarily The dirt stuck to can take easily wiped by a simple wiping with water, prolonged over to prevent the structure surface is contaminated, can be kept clean.

  The reason why the anti-staining coating composition of the present invention exhibits such anti-staining effect over a long period of time is not necessarily clear, but the alkoxy group (-OR) of the organosilicate is hydrolyzed. It is considered that the hydroxyl group (—OH) of a part is combined with aluminum ion to be modified and stabilized, thereby stabilizing the surface charge, improving the dispersion stability, and improving the storage stability as a result.

  The coating composition for preventing contamination of the structure surface according to the present invention can impart hydrophilicity to various structure surfaces immediately after application without requiring special treatment such as acid treatment. Not only can it exhibit excellent anti-contamination properties, but it also has excellent storage stability and drying properties, as well as excellent handleability, and excellent adhesion and transparency. It is possible to form a coating film having a good appearance.

Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.
[Example 1]
Tetramethylsilicate (TMS: manufactured by Tama Chemical Co., Ltd.) 49.4g, ethanol 912g (4,680 parts by weight with respect to 100 parts by weight of SiO2 of TMS Si atoms), and pure water 950g (TMS) 4,870 parts by weight with respect to 100 parts by weight of Si atoms of Si atoms), and hydrolyzed at 80 ° C. for 10 minutes under heating and reflux. After the hydrolysis reaction was completed, the reaction mixture was allowed to cool, and then 0.096 g of aluminum triisopropoxide (ATiP) (0.065 parts by weight as Al with respect to 100 parts by weight of SiO2 of TMS Si atoms) was added, The coating composition of Example 1 was prepared by mixing uniformly.

About the obtained coating composition of Example 1, the storage stability, corrosivity, wettability, transparency, coating film appearance, and the stain | pollution | contamination condition 6 months after application | coating were investigated with the following method.
[Storage stability]
The coating composition was sealed in a glass container, kept at 60 ° C. for 6 months, and then returned to room temperature. The state in the glass container was visually observed, ◎: No change was observed, ○: Slightly Evaluation was made in four stages: white: turbid white: x: gelled.

[Corrosive]
The coating composition was placed in a tin can and allowed to stand, and the color state after one week was visually observed. ◎: No change was observed, ○: Slightly yellowish, and X: Yellow It was evaluated in three stages: colored.

[Wettability, transparency, appearance of coating film]
The coating composition was applied on a glass plate, and the wettability was visually observed immediately after application, ◎: spread in a film shape, △: slightly repelled from the glass surface, and ×: repelled from the glass surface It was evaluated in three stages of water droplets, and the transparency was visually observed after 1 hour of coating. A: Transparent, Δ: Slightly white, and X: White The film was evaluated in three stages, and the appearance of the coating film was visually observed after 1 hour of coating, ◎: completely dried to form a film, Δ: dried to form a film, but transparent Evaluation was made in three stages: poor feeling and x: powdered without film formation.

[Contamination after 6 months of application]
The coating composition was applied onto a glass plate, and after 6 months had elapsed from the application, the state of dirt on the coating film was visually observed to examine dust adhesion and the presence of rain stripes.
The results are shown in Table 1.

[Example 2]
A coating composition was prepared in the same manner as in Example 1 except that 72.4 g of tetraethyl silicate (TES) was used instead of tetramethyl silicate (TMS) in Example 1 (100 Si2 equivalent of TES Si atom). 4,680 parts by weight of ethanol, 4,870 parts by weight of pure water, and 0.065 parts by weight of ATiP Al), storage stability, corrosiveness, wettability, transparency, coating appearance, and The state of contamination after 6 months of application was examined.

Example 3
A coating composition was prepared in the same manner as in Example 1 except that 72.4 g of triethyl silicate (TrES) was used instead of tetramethyl silicate (TMS) in Example 1 (100 Si 2 equivalents of TrES Si atoms). 4,680 parts by weight of ethanol, 4,870 parts by weight of pure water, and 0.065 parts by weight of ATiP Al), storage stability, corrosiveness, wettability, transparency, coating appearance, and The state of contamination after 6 months of application was examined.

Example 4
A coating composition was prepared in the same manner as in Example 1 except that 0.019 g of aluminum triethoxide (ATE) was used instead of 0.096 g of aluminum triisopropoxide (ATiP) of Example 1 (TMS (4,680 parts by weight of ethanol, 4,870 parts by weight of pure water, and 0.016 parts by weight of ATE for 100 parts by weight of SiO2 in terms of SiO2), storage stability, corrosivity, wettability, and transparency in the same manner as in Example 1. Property, appearance of the coating film, and soil condition after 6 months of application.

Example 5
The nonionic surfactant “polyoxyethylene polyoxypropylene ether” was added to the coating composition of Example 1 in an amount of 1 part by weight with respect to 1000 parts by weight, and stored in the same manner as in Example 1. Stability, corrosivity, wettability, transparency, appearance of the coating film, and the state of contamination after 6 months of application were examined.

Example 6
The photocatalyst “anatase-type titanium oxide (trade name: titanium (IV) oxide manufactured by Kanto Chemical Co., Ltd.)” was added to the coating composition of Example 1 in an amount of 10 parts by weight with respect to 1000 parts by weight. In the same manner as in Example 1, the storage stability, corrosivity, wettability, transparency, appearance of the coating film, and the state of contamination after 6 months of application were examined.

[Comparative Example 1]
A coating agent in the same manner as in Example 1 except that 39.6 g of tetramethyl silicate oligomer (MS-51: trade name, manufactured by Tama Chemical Industry Co., Ltd.) was used instead of tetramethyl silicate (TMS) in Example 1. A composition was prepared (4,680 parts by weight of ethanol, 4,870 parts by weight of pure water and 0.065 parts by weight of Al of ATiP with respect to 100 parts by weight of Si atoms of MS-51), and stable storage as in Example 1. Property, corrosivity, wettability, transparency, appearance of coating film, and stain condition after 6 months of application.

[Comparative Example 2]
A coating composition was prepared in the same manner as in Example 1 except that aluminum triisopropoxide was not added in Example 1, but it was gelled after 12 hours.

[Comparative Example 3]
A coating composition was prepared in the same manner as in Example 1 except that 0.18 g of aluminum nitrate nonahydrate (NA9H) was used instead of aluminum triisopropoxide (ATiP) of Example 1 (TMS (4,680 parts by weight of ethanol, 4,870 parts by weight of pure water and 0.065 parts by weight of NA9H with respect to 100 parts by weight of SiO2 in terms of Si atoms), storage stability, corrosivity, wettability, and transparency in the same manner as in Example 1. The appearance of the coating film and the state of contamination after 6 months of application were examined.

[Comparative Example 4]
A coating composition was prepared in the same manner as in Example 1 except that 0.096 g of titanium tetraisopropoxide (TTiP) was used instead of aluminum triisopropoxide (ATiP) in Example 1 (TMS Si (4,680 parts by weight of ethanol, 4,870 parts by weight of pure water, and 0.083 parts by weight of Ti of TiTiP) with respect to 100 parts by weight of the SiO2 equivalent of atoms), storage stability, corrosivity, wettability, transparency in the same manner as in Example 1. The appearance of the coating film and the state of contamination after 6 months of application were examined.

[Comparative Example 5]
A coating composition was prepared in the same manner as in Example 4 except that 0.019 g of aluminum tris (acetylacetonate) (ATAA) was used instead of aluminum triisopropoxide (ATiP) of Example 1 (TMS 4,680 parts by weight of ethanol, 4,870 parts by weight of pure water, and Al of Al TAAA with respect to 100 parts by weight of Si2 of Si atoms 0.016 parts by weight) In the same manner as in Example 1, the storage stability, corrosivity, wettability, transparency, appearance of the coating film, and stain condition after 6 months of application were examined.

[Comparative Example 6]
A coating composition was prepared in the same manner as in Example 1 except that 2 g of 60 wt% nitric acid was used instead of aluminum triisopropoxide (ATiP) in Example 1 (100 wt. 4,680 parts by weight of ethanol and 4,870 parts by weight of pure water), storage stability, corrosiveness, wettability, transparency, appearance of coating film, and stain condition after 6 months of application as in Example 1. Examined.

[Comparative Example 7]
A photocatalyst (the same anatase-type titanium oxide as in Example 6) was added at a ratio of 10 parts by weight to the 1,000 parts by weight of the coating composition of Comparative Example 6, but a white precipitate was formed after 1 hour. And separated into a clear liquid and a precipitate.

[Comparative Example 8]
In Example 1, a coating composition was prepared in the same manner as in Example 1 except that aluminum triisopropoxide (ATiP) was added in the hydrolysis step. The corrosiveness, wettability, transparency, appearance of the coating film, and the state of contamination after 6 months of application were examined.

The results of Examples 1 to 6 and Comparative Examples 1, 3, 5, 6, and 8 are shown in Table 1.

  According to the coating composition for preventing contamination of the structure surface of the present invention, the structure does not require troublesome acid treatment, and without using a catalyst that causes damage to the surface of the structure or application restrictions. By simply applying on the surface, the surface of this structure is not only excellent in stain resistance, but also has a coating film with excellent antifouling resistance, storage stability, drying properties, adhesion, and transparency immediately after application. It can be formed and is very useful industrially.

Claims (5)

The following general formula (1)
HxSi (OR) y (1)
(However, R shows a C1-C3 alkyl group, x and y are the integers in any one of 0-4, and the sum x + y of both shows the integer which is 4, y is 2-4. R may be the same or different from each other.) 100 parts by weight of the organosilicate represented by (in terms of SiO2 of Si atoms) is soluble in 60 to 50,000 parts by weight of water and the above organosilicate and water. In the hydrolysis reaction product obtained by hydrolysis in the presence of water / solvent with 60 to 50,000 parts by weight of the solvent, 100 parts by weight of organosilicate used as a raw material (in terms of SiO2 of Si atoms) A coating composition for preventing contamination of the structure surface, comprising 0.01 to 1 part by weight of aluminum alkoxide as Al.   The coating composition for preventing contamination of the structure surface according to claim 1, wherein the organosilicate is a monomer of alkoxysilane.   The coating composition for preventing contamination of a structure surface according to claim 1 or 2, wherein the organosilicate is one or a mixture of two or more selected from tetramethoxysilane, tetraethoxysilane and triethoxysilane.   The coating composition for preventing contamination of the structure surface according to any one of claims 1 to 3, wherein the solvent is a water-soluble alcohol.   The aluminum alkoxide has an aluminum content of 12% by weight or more. The coating composition for preventing contamination of a structure surface according to any one of claims 1 to 4.