JP5452368B2 - Coating composition imparting antifouling property, coated product using the same, and method for producing coated product - Google Patents

Description

  The present invention relates to a coating composition, a coated article using the same, and a method for producing the coated article. More specifically, the present invention relates to a coating composition for imparting antifouling property to a building material (exterior building material) used outdoors, a coated product using the same, and a method for producing a coated product.

  Conventionally, a treatment for imparting hydrophilicity or water repellency to the surface of a building material has been performed for the purpose of preventing the contamination of the building material used outdoors.

  Among these, as a method for imparting hydrophilicity, a method of forming a film made of a hydrophilic resin on the surface of the building material, a method of applying a surfactant to the surface of the building material, a method of using a photocatalyst, and the like are known. As a method using a photocatalyst, for example, a method of imparting antifouling performance by using a silicone resin as a binder component and fixing photocatalytic titanium oxide on the surface of the coating film has been proposed (see Patent Document 1).

JP 2006-200325 A

  However, since building materials used outdoors are required to have long-term durability, when using a hydrophilic agent such as polyvinyl alcohol or a surfactant such as sodium alkyl ether sulfate, the hydrophilic performance is temporary. There is no permanent antifouling property.

  In a method in which a silicone resin is used as a binder component and the photocatalytic titanium oxide is fixed on the surface of the coating film, a conventionally proposed technique requires a relatively large amount of binder component relative to the photocatalytic titanium oxide. Therefore, most of the photocatalytic titanium oxide is buried in the binder component, and only a part of the surface appearing on the surface can be used.

  In addition, the silicone resin as the binder component is a silanol group that is hydrolyzed by an alkoxy group that is a reactive functional group, and imparts hydrophilicity. Since the silanol group itself decreases, the hydrophilicity gradually decreases.

  Moreover, since building materials used outdoors are generally required to have a low gloss appearance, many base coating films to which an antifouling coating film is applied have low gloss specifications. However, when the coating material for forming the antifouling coating film is an aqueous coating material, the gloss increases due to the large amount of binder components in the antifouling coating film.

  The present invention has been made in view of the circumstances as described above, and is capable of maintaining antifouling properties and weather resistance over a long period of time, and a coating composition that does not impair the appearance as an exterior building material, and It is an object to provide a coated product used and a method for producing the coated product.

  The coating composition of the present invention is characterized by containing hydrophilic metal oxide fine particles having an average particle diameter of 10 to 300 nm, a binder component, a surface tension adjusting agent, and a solvent component.

  In this coating composition, it is preferable to contain 60 mass% or more of silica fine particles as metal oxide fine particles with respect to the total amount of metal oxide fine particles.

  In the coating composition, the content of the metal oxide fine particles is preferably 90% by mass or more in terms of a solid content ratio with respect to the total solid content of the coating composition.

  In this coating composition, the binder component is preferably a hydrolyzable organosilane and / or a partial hydrolyzate thereof.

  In this coating composition, the solvent component is preferably a mixed solvent of water and an organic solvent that can be mixed with water.

  The coated product of the present invention is characterized in that a coating film of the coating composition is formed as a surface layer on an object to be coated. In this coated product, the coating film of the coating composition is preferably formed on the surface of the object to be coated on which a silicone base coating film having a contact angle with water of 80 ° or more is formed. And the manufacturing method of the coated article of this invention is characterized by apply | coating the said coating composition and forming a coating film, when a silicone type base coating film is a semi-hardened state.

  According to the coating composition, the coated product, and the manufacturing method of the coated product of the present invention, the antifouling property and the weather resistance can be maintained for a long time, and the appearance as an exterior building material is not impaired.

  The present invention is described in detail below.

  The coating composition of the present invention contains, as essential components, hydrophilic metal oxide fine particles having an average particle size of 10 to 300 nm, a binder component, a surface tension adjusting agent, and a solvent component.

  In the present invention, the metal oxide fine particles blended in the coating composition have hydrophilicity. Here, the hydrophilic property means that the contact angle with water on the surface of the coating film formed by the metal oxide fine particles of one kind or a mixture of two or more kinds blended in the coating composition is less than 40 °. means.

  Examples of the metal oxide fine particles blended in the coating composition include silica fine particles, alumina fine particles, mica fine particles, talc fine particles, titanium oxide fine particles, cerium oxide fine particles, zinc oxide fine particles, and calcium oxide fine particles. These may be used alone or in combination of two or more. These may be surface-treated to impart hydrophilicity.

  In consideration of not impairing the design of the base coating film, colorless or white metal oxide fine particles having no specific wavelength absorption in the visible light region are preferable. In consideration of the point that the refractive index of the metal oxide fine particles does not impair the design properties of the base coating film, it is preferable that the refractive index of the metal oxide fine particles is equivalent to the binder component and filler component used in the base coating film. In view of hydrophilic performance, it is preferable to use metal oxide fine particles having a low refractive index, which are generally considered to be highly hydrophilic, alone or as a mixture thereof.

  The average particle diameter of the metal oxide fine particles is 10 nm to 300 nm, preferably 10 nm to 150 nm. If the average particle size of the metal oxide fine particles is too small, it may be buried in the unevenness of the base coating film or the binder component, and the performance may not be exhibited. If the average particle size of the metal oxide fine particles is too large, a large amount of binder component may be required for fixing, or the design of the base may be impaired.

  In the present invention, the average particle diameter of the metal oxide fine particles is the median diameter (D50) of particles measured by dispersing in a dispersion medium (organic solvent, water, etc.) using a laser diffraction / scattering particle size distribution measuring device. Can be sought.

  When two or more types having different average particle diameters within the above range are blended, the surface irregularities and the surface area are increased, so that hydrophilicity is more exhibited and excellent antifouling properties can be obtained over a long period of time.

  In this invention, it is preferable to contain 60 mass% or more of silica fine particles with respect to the whole quantity of metal oxide fine particles as metal oxide fine particles. Thereby, antifouling property and appearance can be made particularly excellent.

  The content of the metal oxide fine particles is preferably 90% by mass or more in terms of a solid content ratio with respect to the total solid content of the coating composition. Thereby, antifouling property and appearance can be made particularly excellent.

As a binder component mix | blended with a coating composition in this invention, it is preferable that they are a hydrolysable organosilane and / or its partial hydrolyzate. The hydrolyzable organosilane, for example, _{(where n} represents an integer of 0 to 3.) In formula R _n SiX 4-n can be used those represented by.

  Here, each R independently represents a substituted or unsubstituted monovalent hydrocarbon group, and each X independently represents a hydrolyzable group. As the hydrocarbon group R, a hydrocarbon group having 1 to 8 carbon atoms is preferable, and specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, etc. Or a linear or branched alkyl group.

  Examples of the hydrolyzable group X include a substituted or unsubstituted monovalent alkoxy group, and the alkyl group contained in the alkoxy group preferably has 1 to 8 carbon atoms, and has 3 carbon atoms. The above may be linear such as n-propyl, n-butyl, etc., and has a branch such as isopropyl, isobutyl, t-butyl. May be. Moreover, you may have functional groups, such as an epoxy group, an amino group, and a thiol group, as a substituent.

  The amount of water required to hydrolyze the alkoxide (partial hydrolysis) is not particularly limited, but it is preferable to hydrolyze with 0.001 mol or more of water with respect to 1 mol of the hydrolyzable group.

  Moreover, in order to shorten the time which a manufacturing process requires, a catalyst can be used as needed. Although it does not specifically limit as a catalyst, For example, an acidic catalyst or a basic catalyst can be used.

  Examples of the acidic catalyst include organic acids such as acetic acid, chloroacetic acid, citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, malonic acid, toluenesulfonic acid, and oxalic acid, Inorganic acids such as hydrochloric acid, nitric acid and halogenated silane, acidic sol-like fillers such as acidic colloidal silica and oxidized titania sol can be used. These may be used alone or in combination of two or more.

  As the basic catalyst, for example, sodium salts such as ammonia, sodium hydroxide, sodium acetate, sodium carbonate, sodium hydrogen carbonate, basic colloidal silica, basic titania sol and the like can be used. These may be used alone or in combination of two or more.

  The alkoxide hydrolysis (partial hydrolysis) may be performed, for example, by heating to about 40 to 100 ° C., if necessary.

  In the present invention, the solvent component blended in the coating composition is used to adjust the metal oxide fine particles and the binder component to arbitrary concentrations. The solvent component is preferably a mixed solvent of water and an organic solvent that can be mixed with water.

  Examples of organic solvents that can be mixed with water include lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol, and isobutanol, ethylene glycol such as ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether. Derivatives, diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether, diacetone alcohol and the like can be used. These may be used alone or in combination of two or more.

  The solvent component is preferably one that does not inhibit the dissolution or curing of the base coat component when the silicone base coat is applied in a semi-cured state. In consideration of the leveling properties, pot life of the coating composition, film thickness and coating film performance, it is preferable to adjust the solid content to be 0.1 to 10% by mass.

  In the present invention, the surface tension adjusting agent blended in the coating composition is used for adjusting the surface tension of the coating composition and applying it with good leveling by matching with the surface energy of the object to be coated.

  The surface tension adjusting agent is not particularly limited as long as it can be mixed with the coating composition and can reduce the surface tension. For example, what is generally called a surfactant, leveling agent, or wetting agent is used. it can.

  As the surfactant, any of anionic, cationic and nonionic properties can be used.

  Examples of the anionic surfactant include higher alcohol sulfate (Na salt or amine salt), alkyl allyl sulfonate (Na salt or amine salt), alkyl naphthalene sulfonate (Na salt or amine salt), alkyl naphthalene sulfone. An acid salt condensate, an alkyl phosphate, a dialkyl sulphosuccinate, a rosin soap, a fatty acid salt (Na salt or amine salt) and the like can be used.

Examples of the cationic surfactant include octadecylamine acetate, imidazoline derivative acetate, polyalkylene polyamine derivative or a salt thereof, octadecyltrimethylammonium chloride, trimethylaminoethylalkylamide halide, alkylpyridinium sulfate, alkyltrimethylammonium halide, etc. Can be used.
Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylolamine, polyoxyethylene alkylamide, sorbitan alkyl ester. Polyoxyethylene sorbitan alkyl ester and the like can be used.

  As a leveling agent and a wetting agent, a silicone-modified type, a fluorine type, or the like can be used.

  Said surface tension regulator may be used individually by 1 type, and may use 2 or more types together.

  The content of the surface tension modifier is preferably in the range of 0.01 to 1.0% by mass in terms of the solid content ratio with respect to the total solid content of the coating composition. If the surface tension modifier content is too low, it may not be applied with good leveling. If the surface tension modifier content is too high, the pot life of the paint and the appearance, hydrophilicity, and antifouling properties of the coating will decrease. There is a case.

  The coating composition of the present invention can be prepared by mixing the above components according to a conventional method. In addition, in the coating composition of this invention, other components other than said each component can be mix | blended within the range which does not impair the effect.

  When the coating composition of the present invention is applied to an object to be coated to form a coating film, the method for applying the coating composition is not particularly limited, and various methods can be used. For example, usual methods such as brush coating, spray coating, dipping (dipping, dip coating), roll coating, flow coating, curtain coating, knife coating, spin coating, and bar coating can be appropriately selected.

  Although the thickness of the coating film formed as a surface layer by the coating composition of this invention is not specifically limited, For example, it can be set as about 0.05-10 micrometers. Considering the point that the coating film stably adheres and holds to the surface of the object to be coated over a long period of time and prevents the occurrence of cracks and peeling, the thickness of the coating film is preferably 0.05 to 2 μm, 0.1 ˜1 μm is more preferable.

  In addition, a coating composition is formed on the surface of an object on which a silicone base coating film having a contact angle with water of 80 ° or more is formed, and the silicone base coating film is semi-cured. In the state, it is preferable to form a coating film by applying a coating composition. In addition, as such a silicone-based undercoating film, this type is conventionally used which contains the hydrolyzable organosilane and / or a partial hydrolyzate thereof as described above and, if necessary, other components such as a filler component. What is used for the base coating film of this can be used.

  Here, the semi-cured state of the silicone-based undercoat means a state in which the touch-drying level is obtained after the coating for the silicone-based undercoat is applied. By applying the coating composition of the present invention in this semi-cured state, it is possible to strengthen the adhesion with the base coating without using a large amount of a binder component, and to obtain a coating with an excellent appearance. it can.

  The method for curing the coating film by the coating composition of the present invention applied to the object to be coated and the method for completely curing the above-mentioned semi-cured silicone base coating film are not particularly limited and are appropriately known methods. Etc. can be applied. The curing temperature is not particularly limited, and a wide temperature range from room temperature to heating temperature can be applied depending on the desired coating film performance and the presence or absence of the use of a curing catalyst.

  The coating composition of the present invention can be suitably used for imparting antifouling properties to building materials used outdoors.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following description, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.
<Example 1>
A metal oxide fine particle aqueous dispersion was added to 10 parts of tetraethoxysilane and 98 parts of isopropyl alcohol, and well mixed using a disper. The metal oxide fine particle aqueous dispersion uses colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name “ST-O”: average particle diameter of 10 to 20 nm), and has a solid content ratio to the total solid content of the coating composition. It compounded so that it might become 0.9 in conversion. In addition, colloidal silica has a contact angle with water on the surface of the coating film formed to be less than 40 °.

  After stirring this mixture for 1 hour, it is diluted with ion-exchanged water so that the total solid content becomes 3%, and 0.3 part of a surface tension adjusting agent (product name “coatosil 1211” manufactured by Momentive Performance Materials) is added. Thus, a coating composition was prepared.

This coating composition is applied to a building material prepared by applying a semi-cured water-repellent inorganic coating film (silicone base coating film having a contact angle with water in the cured state of 80 ° or more) as a base coating film. And antifouling building material was obtained by baking for 2 minutes at 200 degreeC.
<Example 2>
Example 1 is the same as Example 1 except that colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name “ST-OL”: average particle diameter of 40 to 50 nm) is used as the metal oxide fine particle aqueous dispersion. A coating composition was prepared in the same manner. In addition, colloidal silica has a contact angle with water on the surface of the coating film formed to be less than 40 °. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Example 3>
In Example 1, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name “ST-O”: average particle diameter of 10 to 20 nm) and titanium oxide sol (manufactured by Taki Chemical Co., Ltd.) were used as the metal oxide fine particle aqueous dispersion. , Trade name “Tynoc AM-15”: The average particle size was 10 nm, and the mass ratio in terms of solid content was set to 2: 1. Otherwise, a coating composition was prepared in the same manner as in Example 1. Colloidal The mixture of silica and titanium oxide sol has a contact angle with water of the coating surface of the coating film of less than 40 ° By applying this coating composition in the same manner as in Example 1, an antifouling building material is obtained. Obtained.
<Example 4>
In Example 1, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name “ST-O”: average particle diameter of 10 to 20 nm, trade name “ST-OL”: average particle diameter as an aqueous dispersion of metal oxide fine particles. 40-50 nm) and titanium oxide sol (manufactured by Taki Chemical Co., Ltd., trade name “Tynoc AM-15”), the mass ratio in terms of solid content was set to 1: 1: 1. Otherwise, a coating composition was prepared in the same manner as in Example 1. The mixture of colloidal silica and titanium oxide sol has a contact angle of less than 40 ° with water on the surface of the coating film. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Example 5>
In Example 1, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name “ST-O”: average particle diameter of 10 to 20 nm) and cerium oxide sol (manufactured by Taki Chemical Co., Ltd.) were used as the metal oxide fine particle aqueous dispersion. , Trade name “Nidoral U-15”: average particle diameter 8 nm), and the mass ratio in terms of solid content was 2: 1. Otherwise, a coating composition was prepared in the same manner as in Example 1. The mixture of colloidal silica and cerium oxide sol has a contact angle of less than 40 ° with the water on the coated surface of the coating film. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Example 6>
In Example 1, the amount of colloidal silica blended was 0.5 in terms of the solid content ratio with respect to the total solid content of the coating composition. Otherwise, a coating composition was prepared in the same manner as in Example 1. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Example 7>
In Example 3, the base coating film was completely cured, and then the coating composition was applied to the base coating film. Otherwise, an antifouling building material was obtained in the same manner as in Example 3.
<Comparative Example 1>
In Example 1, a coating composition was prepared in the same manner as in Example 1 except that the resin component was adjusted using an acidic catalyst (0.1N hydrochloric acid) and the metal oxide fine particles were not added. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Comparative example 2>
In Example 1, titanium oxide sol (manufactured by Taki Chemical Co., Ltd., trade name “Tynoc AM-15”) was used as the aqueous dispersion of metal oxide fine particles. Otherwise, a coating composition was prepared in the same manner as in Example 1. Note that the titanium oxide sol has a contact angle of 40 ° or more with water on the surface of the coating film formed into a film. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.
<Reference Example 1>
In Example 1, a coating composition was prepared in the same manner as in Example 1 except that 3 parts of the surface tension modifier was added. By applying this coating composition in the same manner as in Example 1, an antifouling building material was obtained.

The following evaluation was performed about the antifouling building material obtained by said Example, the comparative example, and the reference example.
[appearance]
By measuring the Lab value using a spectral color difference meter (manufactured by Konica Minolta: CM-2600d), ΔL before and after coating was determined. The determination was “◯”: less than ΔL3, “Δ”: ΔL3 or more to less than 5 and “x”: ΔL5 or more. Moreover, gloss (60 degree gloss) measurement was also performed using a gloss meter (Kett Co., Ltd .: Multi-Gloss 268). Judgment is in conjunction with visual confirmation, “◯”: less than 2.0 (no difference compared to unpainted board), “Δ”: 2.1 to less than 4.0 (slightly gloss compared to unpainted board) “×”: 4.1 or more (with gloss).
[Hydrophilic]
The contact angle was measured using a water contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.). Judgment was made as follows: ◯: less than 40 °, Δ: 40 ° to less than 60 °, and x: 60 ° or more.
[Initial antifouling property]
The test piece was immersed in an aqueous dispersion of 5% carbon black (manufactured by Degussa: FW-200), pulled up after 5 seconds, and then the attached carbon was washed away using a spray. Then, ΔL before and after the test was obtained by measuring the Lab value using a spectrocolor difference meter (manufactured by Konica Minolta: CM-2600d). The determinations were “◯”: less than ΔL3, “Δ”: ΔL3 or more to less than 5 and “x”: ΔL5 or more.
[Adhesion]
The evaluation method was performed according to JIS 5400.5.2. Using a cutter knife guide, parallel lines were drawn at an interval of 4 mm in 6 vertical and horizontal directions to produce 25 grids. Next, cello tape (registered trademark) (manufactured by Nichiban Co., Ltd.) was applied to the grid and rubbed with an eraser from the top, and then the tape was peeled off at a stretch to evaluate the coating film persistence after the tape was peeled off. Judgment was as follows: “A”: no coating film peeling, “◯”: coating film peeling 2% or less, “Δ”: coating film peeling 10% or less, “x”: coating film peeling 50% or more.

  The evaluation results are shown in Table 1.

  In Examples 1 to 7, a coating composition containing hydrophilic metal oxide fine particles having an average particle size of 10 to 300 nm, a binder component, a surface tension adjusting agent, and a solvent component was used. In this case, the appearance, hydrophilicity, and antifouling properties were improved as compared with Comparative Example 1 in which the metal oxide fine particles were not blended. In particular, as metal oxide fine particles, silica fine particles are contained in an amount of 60% or more with respect to the total amount of metal oxide fine particles, and the content of the metal oxide fine particles is converted into a solid content ratio with respect to the total solid content of the coating composition. When it was 90% or more, great improvement was observed in all of appearance, hydrophilicity, and antifouling properties.

  In Comparative Example 2 in which titanium oxide fine particles were used for the total amount of metal oxide fine particles, the hydrophilicity and antifouling properties were not improved sufficiently.

  In Examples 1 to 6, when the base coating film was in a semi-cured state, the coating composition was applied to form a coating film. After the base coating film was completely cured, the coating composition was applied to form a coating film. Compared with Example 7 formed, the adhesion of the coating film was improved.

  In addition, although the blending of the surface tension adjusting agent is essential, the coating composition may become clouded when an excessive amount exceeding the amount necessary for leveling or the like is blended as shown in Reference Example 1. It is desirable to make the composition suitable for the composition of the composition.

Claims (6)

Contains metal oxide fine particles having an average particle size of 10 to 300 nm and hydrophilic, a binder component, a surface tension adjusting agent, and a solvent component. The content of the metal oxide fine particles is a solid content relative to the total solid content of the coating composition. It is 90 mass% or more converted into ratio, The coating composition characterized by the above-mentioned .   The coating composition according to claim 1, wherein the fine metal oxide particles contain 60% by mass or more of silica fine particles with respect to the total amount of the metal oxide fine particles. The coating composition according to claim 1 or 2, wherein the binder component is a hydrolyzable organosilane and / or a partial hydrolyzate thereof. The coating composition according to any one of claims 1 to 3 , wherein the solvent component is a mixed solvent of water and an organic solvent that can be mixed with water. A coating film of a coating composition containing hydrophilic metal oxide fine particles having an average particle diameter of 10 to 300 nm, a binder component, a surface tension adjusting agent, and a solvent component is formed as a surface layer on the object to be coated , and the coating composition The coated product is characterized in that the coated film is formed on the surface of the object to be coated on which the silicone base coating film having a contact angle with water of 80 ° or more is formed .   6. A method for producing a coated product according to claim 5, wherein the coating composition is applied to form a coating film when the silicone base coating film is in a semi-cured state. Method.