JP5553297B2 - Coating composition - Google Patents

Description

  The present invention relates to a coating composition, and in particular, used for exterior walls and roofs of buildings, bodies of aircraft, ships, vehicles, etc., glass, wheels, etc., side mirrors for passenger cars, heat exchangers for air conditioners, parabolic antennas, electric wires, etc. Coating compositions to be applied.

  Glass and mirrors installed outdoors or used outdoors, such as passenger car side mirrors and glass, and window glass of houses, are difficult to visually identify when raindrops adhere to them, reducing visibility. To do. Moreover, if raindrops adhere to the outer wall, roof, etc. of the building, the aesthetics are impaired. Furthermore, various problems occur when dew condensation or icing occurs on parabolic antennas, electric wires, etc., or when water droplets adhere to the heat exchanger of an air conditioner. Therefore, the development of a technique for imparting water repellency to the surface of a building such as an outer wall of a building, a parabolic antenna, an electric wire, glass, a mirror, a heat exchanger or the like has been performed.

  For example, JP 2003-306670 A, JP 2004-149700 A, JP 2004-149701 A, and JP 2005-218980 A use water-repellent particles having hydrophobic surfaces. Although it is disclosed to form a coating film, all show high water repellency in the initial stage, but the sliding resistance against wipers and the like is not yet sufficient, and when it is actually used outdoors, it is raining heavily. When hit or used on the windshield of an automobile, the coating film was easily peeled off, and it was not resistant to actual use.

  For the purpose of improving durability, JP-A-10-259037 and JP-A-2000-144122 disclose that heat treatment is performed after coating a coating solution, but high heat treatment at 350 ° C. or higher is disclosed. It is necessary and the operation is very complicated, and the heat resistance of the object to be coated has been a big problem. Japanese Patent Application Laid-Open No. 2008-007363 discloses a water / oil repellent / antifouling glass plate whose surface is covered with sintered and fixed water / oil repellent / antifouling transparent fine particles. A heat treatment at 250 ° C. or higher was necessary in the ligation process, and the same problems as described above were involved.

  Japanese Patent Application Laid-Open No. 2002-038094 discloses that a superhydrophobic film having a contact angle of 140 ° or more is formed by applying a coating liquid in which solid lubricant particles are dispersed in an organic / inorganic hybrid sol liquid. However, this super water-repellent film is inferior in transparency. Japanese Patent Application Laid-Open No. 2003-206476 discloses forming a super water-repellent film by using a super water repellent composition obtained by mixing hydrophobically treated inorganic fine particles and an organic silicon compound. If it is used in a windshield where the durability is not enough, where it is exposed to heavy rain, or when the wiper is forced to slide, the super-water-repellent coating will be easily peeled off, and it will not withstand practical use. There wasn't.

JP 2003-306670 A JP 2004-149700 A JP 2004-149701 A JP 2005-218980 A Japanese Patent Laid-Open No. 10-259037 JP 2000-144122 A JP 2008-007363 A JP 2002-038094 A JP 2003-206476 A

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to form a super-water-repellent coating that can easily form a coating, excellent in transparency, and excellent in durability. Is to provide a coating composition capable of forming Another object of the present invention is to provide a method for forming a super-water-repellent coating film using this coating composition.

In view of the above problems, the present inventors have intensively studied, and as a result, completed the present invention.
That is, the coating composition of the present invention has (A) silicon alkoxide, (B) alcohols, (C) water, (D) acids, and (E) a hydrophobic surface and an average primary particle size of 100 nm or less. It contains fine particles, and is characterized in that (A) silicon alkoxide, (B) alcohols, (C) water, and (D) acids are mixed and matured.

  In the present invention, the ratio of (A) silicon alkoxide to (E) fine particles having a hydrophobic surface and an average primary particle size of 100 nm or less is expressed by weight ratio (A) / (E) = 3/1 to 16 / 1.

  In the present invention, the acid (D) is preferably at least one selected from inorganic acids.

  In the method for forming a coating film of the present invention, (A) silicon alkoxide, (B) alcohols, (C) water, and (D) acids are mixed and after aging is completed, (E) the surface is hydrophobic. In the method, a coating solution is prepared by adding fine particles having an average primary particle size of 100 nm or less, and the coating solution is applied to an object to be coated, followed by heat treatment to form a coating film.

  Here, as a method of applying the coating solution to the object to be coated, any of flow coating method, dip coating method, spray coating method, gravure coating method, roll coating method, bar coating method, or screen printing method Is preferably adopted.

  Further, the object to be coated is preferably a glass substrate, a metal substrate, or a plastic substrate.

  In the present invention, the heat treatment can be performed at a temperature of 0 ° C. or higher and lower than 250 ° C.

In the present invention, after the heat treatment, it is preferable to further perform a hydrophobic treatment by applying hexyltrimethoxysilane containing no fluorine or heptadecafluorodecyltrimethoxysilane containing fluorine.
In this case, the hydrophobic treatment is preferably performed at a temperature of 40 ° C. or higher and 90 ° C. or lower.

ADVANTAGE OF THE INVENTION According to this invention, it can provide the coating composition which can form the super-water-repellent film which was excellent in transparency and excellent in durability, and using this coating composition, it can provide simply. A transparent and durable super water-repellent film can be formed.

  The coating composition of the present invention comprises (A) silicon alkoxide, (B) alcohols, (C) water, (D) acids, and (E) fine particles having a hydrophobic surface and an average primary particle size of 100 nm or less. Contains.

  Examples of (A) silicon alkoxide used in the present invention include tetraalkoxysilanes such as tetraethoxysilane and tetramethoxysilane. Examples of the alkoxide include methoxide, ethoxide, propoxide, isopropoxide, or butoxide. A part of the alkoxy group may be β-diketone, β-ketoester, alkanolamine, alkylalkanolamine, etc. It may be a substituted alkoxide derivative.

  Examples of the (B) alcohol used in the present invention include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, allyl alcohol, ethylene glycol, propylene glycol, 3-methoxy-3-methyl-1-butanol, Or a polar solvent like 1-methoxy-2-propanol is mentioned. Among these, it is preferable to use ethyl alcohol or isopropyl alcohol. These alcohols can be used alone or in combination of two or more. In the present invention, alcohols function as a solvent for stably dispersing fine particles and the like.

  Examples of the (C) water used in the present invention include ion-exchanged water.

  Examples of the acids (D) used in the present invention include inorganic acids such as hydrochloric acid, sulfuric acid, or nitric acid, and organic acids such as acetic acid and formic acid. Among these acids, inorganic acids are preferably used, and hydrochloric acid, sulfuric acid, nitric acid and the like are more preferably used. These acids can be used alone or in combination of two or more. In the present invention, acids are used as a catalyst.

  The fine particles (D) used in the present invention are required to have a hydrophobic surface and an average primary particle size of 100 nm or less. The average primary particle diameter of the fine particles is preferably in the range of 1 to 100 nm, more preferably in the range of 5 nm to 100 nm. This is because if the particle diameter of the fine particles exceeds 100 nm, light scattering occurs on the surface of the coating film, and transparency may not be maintained. That is, the coating film in which the fine particles are attached to the surface of glass or the like has irregularities having the same size and height as the fine particles. Therefore, if fine particles having an average particle diameter of 100 nm or less are attached, the wavelength of visible light ( Mainly about 400 to 800 nm), and the light is not scattered on the surface of the coating film, and the transparency can be maintained. Therefore, when the object to which the coating composition of the present invention is applied is glass, a mirror, etc., the transparency is effectively utilized and it is particularly effective.

  The shape of the fine particles is not limited to a spherical shape in a strict sense. For example, the crystal form or aggregated form may be substantially spherical, cylindrical, scaly, fibrous, indeterminate, or polyhedral.

  The fine particles whose surface is hydrophobic are mainly composed of silicon, titanium, aluminum, zirconium, antimony, tin, tungsten, zinc, iron, cerium, manganese, copper, magnesium, holmium or nickel oxide, or carbon. Of these, silicon oxide is particularly preferable. In this invention, these can be used individually or in mixture of 2 or more types. When the fine particles are formed using zinc oxide, antibacterial and antifungal effects can be further imparted to the coating film surface.

In the present invention, the fine particles having a hydrophobic surface are preferably hydrophobic silica. Here, the term “silica” means not only those that exist strictly in the state of SiO ₂ but also silicon oxide. The fine particles whose surface is hydrophobic means those whose surface is subjected to a hydrophobic treatment. For example, the hydrophobic silica means one whose surface is subjected to a hydrophobic treatment.

  The method for hydrophobizing the surface of the fine particles is not particularly limited as long as it can impart hydrophobicity to the surface of the fine particles, and is appropriately adopted. For example, it is preferable that the surface contains fluorine or an alkyl group. Examples of the method for containing fluorine or an alkyl group on the surface of the fine particles include a method using a silylating agent, a silane coupling agent, or an alkylaluminum (organometallic compound). Here, the silylating agent is a compound in which an alkyl group, an allyl group, a fluoroalkyl group containing fluorine, or the like is bonded to a hydrolyzable silyl group having affinity or reactivity with an inorganic material. Examples of the hydrolyzable group bonded to silicon include an alkoxy group, a halogen, or an acetoxy group. Usually, an alkoxy group such as a methoxy group and an ethoxy group, and chlorine are preferably used. For example, a trimethylsilylating agent, alkylsilanes, arylsilanes, or fluoroalkylsilanes can be mentioned.

  In the present invention, the hydrophilic fine particles may be hydrophobized to make the surface hydrophobic.

In the present invention, it is preferable to perform a hydrophobizing treatment by a dry method. Here, the hydrophobizing treatment by dry means that the hydrophilic fine particles and the hydrophobizing agent are reacted in the gas phase. As the hydrophobizing agent, monomethyltrichlorosilane, dimethyldichlorosilane, hexamethyldisilazane, or silicone oil can be used. For example, silicon dioxide synthesized at high heat can be hydrophobized in a fluidized bed using dimethyldichlorosilane. In addition, it is preferable to implement hydrophobization reaction at the temperature of 400-600 degreeC. The hydrophobizing treatment by wet means that the hydrophilic fine particles and the hydrophobizing agent are reacted in a solution.
The degree of hydrophobicity of the fine particles having a hydrophobic surface is preferably designed as appropriate according to the material of the object to be coated and the type of organic solvent used.

  Examples of the hydrophobic silica containing a methyl group on the silica surface include, for example, a trade name “Leolosil HM20S” (manufactured by Tokuyama Corporation, average primary particle size 12 nm), and a trade name “Leolosil HM30S” (manufactured by Tokuyama Corporation, average Primary particle diameter 7 nm), trade name “Leoroceal HM40S” (manufactured by Tokuyama Corporation, average primary particle diameter 7 nm), trade name “Leoroceal DM30S” (manufactured by Tokuyama Corporation, average primary particle diameter 7 nm), trade name “Leolosil” ZD30S "(manufactured by Tokuyama Co., Ltd., average primary particle diameter 7 nm) and the like can be obtained commercially.

In the present invention, the mixing ratio of the component (A), the component (B), the component (C), the component (D) and the component (E) can be appropriately designed. For example, (A) silicon The mixing ratio of the alkoxide and the fine particles (E) is a weight ratio, and is preferably in the range of (A) component / (E) component = 3/1 to 16/1, and in the range of 9/1 to 11/1. More preferably, it is within.
The mixing ratio of (A) silicon alkoxide and (B) alcohol is preferably in the range of (A) component / (B) component = 1/10 to 4/10 by weight ratio, More preferably, it is in the range of 190-50 / 190.

  In the present invention, (A) silicon alkoxide, (B) alcohols, (C) water, and (D) acids must be separately mixed before mixing with (E) fine particles. . Moreover, these mixed liquids need to be in a state where heat treatment has been performed and ripening has been completed. Here, the state in which the ripening is completed is a state in which the polymerization of silicon dioxide is appropriately performed and the sol-gel of silicon alkoxide is appropriately developed, and the fine particles are taken in in the subsequent mixing step with the fine particles. The state which can exhibit the effect of this application when forming a coating film. In this way, when the liquid mixture in the state of completion of aging is mixed with (E) fine particles and applied to an object to be coated to form a film, the initial water droplet contact angle is 150 ° or more, and the wiper 10 It is possible to realize a coating having a water droplet contact angle of 140 ° or more after the sliding. For example, when the mixed solution is subjected to a heat treatment at a heat treatment temperature of 60 ° C. and a heat treatment time of 12 hours or longer, ripening has been completed.

  When (A) component, (B) component, (C) component and (D) component are mixed and mixed with (E) hydrophobic fine particles in the state where ripening is completed, the carbon dioxide is not removed when ripening is completed. Since the silicon polymer chain is sufficiently long and the adhesion with the hydrophobic fine particles is improved, the durability is considered to be remarkably improved.

  In the present invention, (E) hydrophobic fine particles can be added to the above mixed solution in a state dispersed in a solvent. As a solvent used here, alcohols, such as isopropyl alcohol, can be used, for example, Specifically, the thing similar to what was mentioned by the said (B) alcohol can be used. In addition, the usage-amount of (B) component (alcohol) in this invention does not include the usage-amount of alcohol used in order to disperse | distribute this (E) component.

  The amount of the fine particles added is preferably in the range of 0.1% by mass or more and 15.0% by mass or less in the coating composition, and more preferably in the range of 1% by mass or more and 5% by mass or less. preferable. This is because sufficient water repellency may not be obtained if the amount of fine particles added is less than 0.1% by mass, and transparency may be inferior if it exceeds 15.0% by mass.

  In the coating composition of the present invention, additives usually used in general coating liquids and the like can be added within a range not impairing the effects of the present invention. For example, an ultraviolet absorber, an antioxidant, etc. Coloring, flavoring, or preservatives can be added.

  In the present invention, it is preferable that fine particles having a hydrophobic surface and an average primary particle size of 100 nm or less are dispersed by a cavitation action in a dispersion solvent such as alcohols. Here, in order to cause the cavitation action, for example, fine particles are placed in a dispersion solvent and dispersed using an ultrasonic disperser. The fine particles dispersed by the cavitation action exhibit unexpected super water repellency, but this mechanism is not clear. When the dispersion solvent is irradiated with ultrasonic waves, a high pressure portion and a low pressure portion appear, and gas dissolved in water is generated as cavities (bubbles). It is considered that the bubbles are instantaneously contracted and broken to disperse the hydrophobic fine particles in a good state or have some action on the fine particles themselves. In addition, super-water repellency may be exhibited even when dispersed by a disperser such as a homogenizer, but adjustment is necessary in consideration of the transparency of the coating film to be formed.

  For example, in a state in which components (A) to (D) are mixed and ripening is completed, (E) a coating composition in which hydrophobic fine particles are dispersed in a dispersion solvent is mixed with an object to be coated such as glass or mirror surface The coating object can be provided with water repellency by being dried after being applied to the surface. Here, the fine particles adhere to the surface of the object to be coated and form irregularities. The unevenness serves to reduce the contact point between the glass and the water droplet. Therefore, it is possible to realize super water repellency such that the contact angle of water droplets is 150 ° to 175 °. The coating composition of the present invention has a water droplet contact angle of 140 ° or more even after the wiper is slid 10 times.

  The method for applying the coating composition of the present invention is not particularly limited, and a general method can be adopted. Examples thereof include a flow coating method, a dip coating method, a spray coating method, a gravure coating method, a roll coating method, a bar coating method, and a screen printing method. These may be used in combination as appropriate.

  The coated composition of the present invention is coated on the object to be coated by the above method and then dried. The drying temperature is preferably 0 ° C. to 100 ° C., and the drying time is preferably 1 minute to 1 hour.

  Next, the coating film applied to the object to be coated is preferably heat-treated, but the temperature is preferably 0 ° C. or higher and lower than 250 ° C. If the heat treatment temperature is too high, for example, if it is 250 ° C. or higher, the heat resistance of the object to be coated itself becomes a problem, so it is preferable that the temperature is not too high.

  In the present invention, after the coating solution is applied, the coating film formed by heat treatment can be further subjected to a hydrophobic treatment (FAS treatment). Specifically, a solution obtained by diluting a fluorine-free alkylsilane (ex. Hexyltrimethoxysilane) or fluorine-containing fluoroalkylsilane (ex. Heptadecafluorodecyltrimethoxysilane) with an organic solvent is brought into contact with the coating film. Can be hydrophobized (ex. Coated). In addition, it is preferable to wash | clean with ethanol etc. after a hydrophobization process. In the present invention, the hydrophobization treatment temperature is preferably in the range of 25 ° C. to 75 ° C., and the treatment time is preferably in the range of 0.5 hour to 8 hours.

  Examples of the fluoroalkylsilane used for the hydrophobic treatment include fluoroalkylsilane (heptadecafluorodecyltrimethoxysilane, trifluoropropyltrimethoxysilane, etc.), alkylsilane (decyltrimethoxysilane, etc.), and the like. For example, trade name “TSL8233” (heptadecafluorodecyltrimethoxysilane, manufactured by Momentive), trade name “KBM-7103” (trifluoropropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), trade name “KBM- 3103 "(decyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like can be obtained commercially. Moreover, as an organic solvent used for dilution, hexane is preferable.

  The coating composition of the present invention can be applied to various coated objects. Examples of coated objects to be coated include glass such as tempered glass, non-alkali glass and quartz glass, metals such as iron, aluminum, stainless steel and copper, plastics such as polyolefin resin, polyester resin, acrylic resin and polycarbonate. , Stones, concrete and the like.

The coating composition of the present invention can be coated on, for example, building window glass, exterior light glass, vehicle window glass, automobile side mirrors, sunglasses, window glass for various instruments, bathroom mirrors, etc. It can also be used for building exterior walls, roofs, fences, automobile / aircraft / ship bodies, mirrors, wheels, and the like. Since a super-water-repellent film is formed on the film surface formed by coating and drying the coating composition of the present invention, it prevents adhesion of water droplets, dust, etc., and maintains aesthetics and ensures visibility. Can be realized. Also, if a super-water-repellent film is formed on the surface of parts that are subject to water droplets unnecessarily, such as heat exchangers in air conditioners, water droplets can be prevented, airflow resistance can be reduced, and A decrease in conductivity can be prevented. In addition, if a super water-repellent coating is formed on a parabolic antenna or an electric wire, condensation and icing can be prevented. Furthermore, according to the present invention, since a transparent coating film can be formed, it can be preferably used for window glass, road mirrors, road signs, signboards and the like of high-rise houses.

  The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical scope of the present invention. In addition, each Example and each comparative example measured and evaluated by the method shown below.

(1) Measurement of initial water droplet contact angle Using a CA-DT type contact angle meter manufactured by Kyowa Interface Science Co., Ltd., 2 μL of water droplets were dropped on the water-repellent film of the sample glass in the atmosphere (about 25 ° C.). The static contact angle of the water droplet was measured.

(2) Washability test This test method assumes sliding with a wiper. Specifically, a commercially available wiper (normal rubber) is set on a washerability tester (manufactured by Toyo Seiki Seisakusho), and a sample The glass repellent film surface was reciprocated a predetermined number of times under the condition of a load of 38 g / cm. After sliding the wiper 10 times, the static contact angle of the water droplet was measured in the same manner as (1) above.

(3) Evaluation of finish (transparency) The water-repellent film was visually observed to evaluate the transparency. However, the evaluation criteria were the following five-level evaluation.
(Evaluation criteria)
5 Fully transparent 4 Slightly cloudy 3 Perceived cloudy when viewed from an angle 2 Perceived cloudy when viewed from the front 1 White

(4) Comprehensive evaluation Comprehensive evaluation was performed about the obtained data based on the following evaluation criteria.
“○” When the water droplet contact angle after sliding the wiper 10 times is 140 ° C. or more and the evaluation score of the finish is 3.5 or more “X” The water contact angle after sliding the wiper 10 times is 140 ° C. Or if at least one of the evaluation points of finish quality is less than 3.5

In the following examples and comparative examples, the following materials were used.
“Leosil HM30S”: hydrophobic silica, solid content 100%, average primary particle size 7 nm, IPA manufactured by Tokuyama Corporation: isopropyl alcohol (alcohol solvent)
"TEOS": Tetraethoxysilane (ethyl silicate) (silicon ethoxide), 99% special grade
EtOH: Ethyl alcohol (alcohol solvent)
Water: ion-exchanged water, 1 μS / cm or less Hydrochloric acid: 2M aqueous hydrochloric acid solution “TSL8233”: heptadecafluorodecyltrimethoxysilane, manufactured by Momentive

Example 1
A sol solution was prepared by mixing 25.25 g of TEOS, 234 mL of ethyl alcohol, 6.48 g of water, and 3 mL of 2M aqueous hydrochloric acid. The mixing ratio is TEOS / EtOH / H ₂ O / HCl = 0.3 / 10 / 0.9 / 0.015 in terms of molar ratio. The sol solution was heat treated and aged. That is, a heat treatment was performed at 20 ° C. for 1 week to obtain a sol solution in which aging was completed.
Separately, hydrophobic silica having a hydrophobic surface and a particle diameter of about 7 nm (trade name “Leosil HM30S”, solid content 100%, manufactured by Tokuyama Corporation) is placed in isopropyl alcohol (IPA), and an ultrasonic disperser The dispersion was used for 1 hour at a frequency of 44 KHz to prepare a 10% concentration hydrophobic silica IPA dispersion (YIH2001).
12 mL of the hydrophobic silica dispersion (YIH2001) was collected with stirring, mixed with 80 mL of the obtained sol solution with stirring, mixed, and then stored statically for 2 hours to prepare a coating solution.
The prepared coating solution was applied three times on a slide glass plate (borosilicate glass) with a thickness of 1.1 mm using a dip coater at a dip speed of 2 mm / s, and the dip speed was 3 mm using the dip coater. EtOH was washed once at / s. Then, after drying at 20 ° C., heat treatment (at 60 ° C. for 12 hours) was performed to form a film, and a glass substrate (sample glass) having a water-repellent film was produced. In addition, the temperature of the slide glass plate at the time of construction was 20 ° C., and the temperature of the coating liquid at the time of construction was 20 ° C.

About the water-repellent film of the obtained sample glass, the initial finish (transparency) was visually evaluated. Further, based on the above measurement method and the like, an initial water droplet contact angle was measured as an initial evaluation of water repellency, and a water droplet contact angle after sliding 10 times with a wiper was measured by a washability test. The results are shown in Table 1.
A glass substrate (sample glass) having a water-repellent film was subjected to a hydrophobic treatment using a 1% hexane solution of “TSL8233” at 60 ° C. for 5 hours. A water-repellent film was obtained.

(Examples 2-19, Comparative Examples 1-13)
Example 1 except that the mixing amount of each component used for forming the sol solution, the aging condition of the sol solution, the number of dip and the cleaning rate, and the heat treatment conditions after coating were changed as shown in Tables 1 to 6 Similarly, a glass substrate (sample glass) having a water-repellent film was produced. The sol solution of Example 14 and the like was prepared by mixing 34.0 g of TEOS, 234 mL of ethyl alcohol, 6.5 g of water, and 3 mL of 2M aqueous hydrochloric acid, and the mixing ratio was TEOS. / EtOH / H ₂ O / HCl = 0.4 / 10 / 0.9 / 0.015. The sol solution of Example 17 and the like was prepared by mixing 42.08 g of TEOS, 234 mL of ethyl alcohol, 7.2 g of water, and 5 mL of 2M aqueous hydrochloric acid, and the mixing ratio was TEOS. / EtOH / H ₂ O / HCl = 0.5 / 10 / 1.0 / 0.025. The sol solution of Comparative Example 9 and the like was prepared by mixing 33.66 g of TEOS, 280 mL of ethyl alcohol, 8.64 g of water, and 4 mL of 2M aqueous hydrochloric acid, and the mixing ratio was TEOS. / EtOH / H ₂ O / HCl = 0.4 / 12 / 1.2 / 0.02. About the obtained sample glass, the same measurement and evaluation as Example 1 were performed. The results are shown in Tables 1-6.

  As is clear from Tables 1 to 3, it was found that the coating films using the coating compositions of Examples 1 to 19 were excellent in transparency and had super water repellency. Moreover, it turned out that the film which uses the coating composition of Examples 1-19 is 140 degrees or more even after 10 times wiper sliding.

  On the other hand, as is clear from Tables 4 to 6, the coating film using the coating compositions of Comparative Examples 1 to 15 has a water contact angle of less than 140 ° after sliding 10 times on the wiper, or is finished. It was inferior in nature and could not satisfy both specifications at the same time.

  The coating composition of the present invention can be effectively used in places where it is necessary to impart super water repellency to buildings, automobiles, aircraft, ships and the like. Further, it can be used particularly effectively in a portion where transparency needs to be maintained.

Claims (8)

The mixed solution of (A) silicon alkoxide, (B) alcohols, (C) water, and (D) inorganic acid is subjected to aging treatment to form a sol-gel of silicon alkoxide, and (E ) Add a fine particle with a hydrophobic surface and an average primary particle size of 100 nm or less to prepare a coating solution in which the fine particle is taken in , apply the coating solution to the object to be coated, and then apply heat treatment to make it transparent. And forming a coating film having a water droplet contact angle of 140 ° or more after sliding 10 times with the wiper . The ratio of (A) silicon alkoxide and (E) fine particles having a hydrophobic surface and an average primary particle size of 100 nm or less is (A) / (E) = 9/1 to 11/1 in weight ratio. The method for forming a coating film according to claim 1 . Any said that (E) the surface content of the fine particles having an average primary particle size of less 100nm in hydrophobic, the coating solution, 1 wt% or more, of claims 1, wherein not more than 5% by weight 2 The method for forming a coating film according to claim 1. The method for forming a coating film according to any one of claims 1 to 3 , wherein the heat treatment is performed at a temperature of 0 ° C or higher and lower than 250 ° C. After the heat treatment, further, any one of claim 1, wherein applying a hydrophobic treatment by applying a heptadecafluorodecyltrimethoxysilane containing hexyl trimethoxysilane or fluorine containing no fluorine 4 1 The method for forming a coating film according to Item. The method for forming a coating film according to claim 5 , wherein the hydrophobizing treatment is performed at a temperature of 40 ° C. or higher and 90 ° C. or lower. As a method for applying the coating solution to the object to be coated, any one of a flow coating method, a dip coating method, a spray coating method, a gravure coating method, a roll coating method, a bar coating method, or a screen printing method is adopted. The method for forming a coating film according to any one of claims 1 to 5 , wherein: The coating film forming method according to any one of claims 1 to 7 , wherein the object to be coated is any one of a glass substrate, a metal substrate, and a plastic substrate.