Self-cleaning member and coating composition

The present invention relates to self-cleaning members and coating compositions.

In recent years, much attention has been paid to how to prevent the adhesion of dirt in living spaces and the external environment. For example, indoors, deterioration of living environment and aesthetics due to oils, molds, algae, and other microorganisms present around us, and deterioration of aesthetics due to stains on the exterior of buildings due to environmental pollution, etc., are problems outdoors. Above all, in the field of building exterior, dirt on the surface of building exterior materials and outdoor structures has become a problem due to environmental pollution. Dust and particles floating in the atmosphere accumulate on the roof and exterior of buildings in fine weather. Sediments are washed away by rainwater as it rains, flowing down the exterior of the building. Furthermore, soot and dust floating in the air are trapped by rain, and the rain that captures soot and dust flows down the exterior of a building and the surface of an outdoor structure. As a result, pollutants adhere to the surface along the rainwater path. Then, when such a surface dries, striped stains appear on the surface.

In addition, the outer walls of high-rise buildings, etc. are hydrophobic stains such as combustion products such as soot and exhaust gas contained in the air, dirt eluted from the sealant above, and pollutants discharged from the exhaust port of the building. Dirty. These hydrophobic stains are light black and significantly spoil the aesthetics of the building. Dirt on building exterior materials and coatings is thought to consist of combustion products such as carbon black and pollutants of inorganic substances such as urban dust and clay particles (see, for example, Non-Patent Document 1).

Conventional wisdom has been that water-repellent paints such as polytetrafluoroethylene (PTFE) are preferable in order to prevent stains on the exterior of buildings, etc. Recently, it is considered that the surface of the coating film should be made as hydrophilic as possible for urban dust containing a large amount of hydrophobic components (see, for example, Non-Patent Document 2).

Under such circumstances, in recent years, there has been known a technique of imparting a hydrophilic component such as a hydrophilic graft polymer or acrylic silicone to a coating material to make the surface of the coating film hydrophilic after coating. Such a coating film exhibits hydrophilicity of 20 to 60 ° in terms of contact angle with water.

However, the contact angle of inorganic dust represented by clay minerals with water is 20 to 50 °, and it has an affinity for the above hydrophilic components with a contact angle of 20 to 60 ° with water, and its surface. This graft polymer coating cannot prevent contamination by inorganic dust because it easily adheres to the clay. Furthermore, on the surface of a coating film having a contact angle of 20 to 60 °, water droplets adhering to the surface due to rainfall or the like do not form a uniform water film, but on the contrary, they tend to remain on the surface as minute water droplets, and the water droplets have a stain component. Is likely to adhere and remain as dirt after all, which may spoil the aesthetic appearance. In addition to the various causes of contamination mentioned above, as an antifouling technology to prevent contamination due to the adhesion of microorganisms such as mold and algae, it has been proposed to make the surface superhydrophilic with a contact angle with water of 20 ° or less. There is. In particular, by coating the exterior of a building with a photocatalytic material, it is attracting attention as an environmentally preferable method that makes it hydrophilic by irradiation with sunlight and decomposes harmful gases such as NOx and a self-cleaning function due to rainfall (for example, Patent Document 1). And Patent Document 2).

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-342526</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2004-143452</text></patcit><nplcit num="1"><text>Architectural Institute of Japan Structural Papers Report, No. 404, October 1989, p.15-24</text></nplcit><nplcit num="2"><text>Monthly Functional Materials, CMC Publishing, Volume 44, August 2005, p.47</text></nplcit>

<p> An object of the present invention is to provide a self-cleaning member capable of easily washing away deposits or contaminants of various properties adhering to a surface simply by exposing them to rainfall or running water.</p>

<p> The present inventors have now set the contact angle hysteresis Δθ (= θa-θr), which is the difference between the forward contact angle θa and the receding contact angle θr, measured on the surface of the base material by the dynamic contact angle measurement by the expansion contraction method. ) Is 80 ° or more and the receding contact angle θr is 25 ° or less. By providing a surface, deposits or contaminants adhering to the surface can be easily washed away simply by exposing them to rainfall or running water. I got the knowledge of. In particular, not only hydrophobic deposits or pollutants, but also iron ions generated by iron corrosion, silicates contained in rainfall, and silicon sealants, which are components that react and adhere to the substrate and induce poor appearance, that is, It was surprisingly found that reactive pollutants can also be easily washed away by suppressing their adsorption on the surface and forming a water film simply by exposing them to rainfall or running water.</p><p> That is, in the self-cleaning member according to the present invention, the contact angle hysteresis Δθ (= θa-), which is the difference between the forward contact angle θa and the backward contact angle θr on the surface, measured by the dynamic contact angle measurement by the expansion contraction method. θr) is 80 ° or more, and the receding contact angle θr is 25 ° or less, and when water is brought in, a water film is formed and ionic or reactive contaminants are washed away without sticking. Is something that can be done.</p><p> Further, the surface of the self-cleaning member according to one aspect of the present invention exhibits a static contact angle with respect to water of 80 to 130 °. Further, the self-cleaning member according to one aspect of the present invention includes a porous surface having a pore size of 10 nm or more and 30 μm or less.</p><p> Further, the coating composition for forming the self-cleaning member according to the present invention comprises hydrophobic resin emulsion particles, whiskers, and a dispersion medium.</p>

<u style="single">Definition</u> In the present invention, the "porous surface" is a surface having an independent pore opening ratio of 5% or more and 75% or less. Here, the pore size is a value calculated by image analysis using a contrast ratio of a scanning electron microscope image: a magnification of 5,000 to 100,000 times. The "opening diameter" is a value obtained by measuring the major axis of an independent opening by image analysis using a contrast ratio of a scanning electron microscope image: a magnification of 5,000 to 100,000 times.

In the present invention, "contact angle hysteresis" is defined as the difference Δθ (= θa-θr) between the forward contact angle θa and the backward contact angle θr in the dynamic contact angle measurement by the expansion contraction method. In the present invention, the forward contact angle θa and the backward contact angle θr are determined by the dynamic contact angle measurement by the expansion contraction method. The "dynamic contact angle" is known as a change in the dynamic contact angle assuming a state in which a liquid moves on a solid surface, such as cleaning or coating. Usually, the contact angle when the interface of the droplet moves forward is defined as the forward contact angle θa, and the contact angle when the droplet interface moves backward is defined as the backward contact angle θr. Details of this definition are disclosed in "The Basics and Applications of Wetting", Realize, Inc., published in 1992, the disclosure of which is included for reference as part of the disclosure herein. In the "expansion contraction method", the tip of the needle of a syringe is pierced into a droplet in contact with a solid surface, and when a certain amount of water is injected, the contact angle when the water droplet advances is set as the forward contact angle, and a constant amount is injected. The contact angle at which the water droplet recedes when water is sucked from the subsequent water droplet can be defined as the receding contact angle.

The dynamic contact angle by the expansion contraction method in the present invention can be measured by, for example, an automatic contact angle measuring device (OCA20) manufactured by Eiko Seiki Co., Ltd. Specifically, first, 0.1 μL of distilled water is adhered onto the test piece by the automatic contact angle measuring device to form water droplets. Next, a stainless steel needle (SNS021 / 011 manufactured by Eiko Seiki Co., Ltd.) with an outer diameter of 0.21 mm and an inner hole diameter of 0.11 mm attached to a glass syringe for 500 μL (DS500 / GT manufactured by Eiko Seiki Co., Ltd.) was attached to the needle. Prick from the center of the water droplet so that the tip is 0.2 mm above the surface of the specimen. Then, the contact angle immediately after injecting 40 μL of distilled water from the needle at a speed of 20 μL / s is set as the forward contact angle, and after standing for 1 second, the contact angle immediately after sucking 40 μL at a speed of 20 μL / s is retracted. The contact angle.

The "self-purifying property" in the present invention means not only hydrophobic pollutants such as soot and granular pollutants such as inorganic dust adhering to the surface each time it receives rainfall or running water, but also ionic pollutants such as iron ions. It also exhibits low adsorptivity to pollutants and reactive pollutants such as those generated from water stains and silicon sealants, and is easily washed away by rainfall or running water, maintaining surface cleanliness almost permanently. Show that. The reactive pollutant refers to a pollutant that chemically bonds with the surface of the member and is difficult to remove easily. Specifically, silicate (salt) or silicon contained in tap water. Examples thereof include alkoxysilane as a sealing material.

<u style="single">Self-cleaning member</u> The surface of the self-cleaning member according to the present invention has a contact angle hysteresis Δθ (= θa-θr), which is the difference between the forward contact angle θa and the receding contact angle θr, measured by dynamic contact angle measurement by the expansion contraction method. It is greater than or equal to ° and the receding contact angle θr is less than or equal to 25 °. This allows deposits or contaminants adhering to the surface to be easily washed away simply by exposing them to rainfall or running water. In particular, in the self-cleaning member of the present invention, not only the surface of hydrophobic deposits or contaminants that the existing hydrophilic surface is good at, but also the surface of ionic pollutants and reactive pollutants that the hydrophilic surface is not good at. Since the adsorption force to the surface is weak, the surface cleanliness can be maintained for a long period of time simply by exposing it to rainfall or running water. Therefore, the self-cleaning member according to the present invention is suitable for use as a building material for an outer wall. Applications that can be expected to be particularly effective include exposed steel materials where elution of iron ions and adhesion to the surface are problems, panel seams and window frame peripheral parts that have been subjected to silicon sealing treatment.

As described above, when the contact angle hysteresis of the surface is 80 ° or more and the receding contact angle θr is 25 ° or less, the mechanism by which excellent self-cleaning property is exhibited is not clear, but in the following cases, it is not clear. It is thought that there is no such thing. However, it goes without saying that the description described below is only a hypothesis, and the present invention should not be limited by the following description. First, as is clear from the above definition, on a surface having a contact angle hysteresis of 80 ° or more, when water droplets are attached from the outside, the difference between the forward contact angle and the backward contact angle becomes large. This means that on a surface arranged vertically or diagonally, the attached water droplet can maintain the water droplet state with a high holding force, that is, it is difficult to flow down until the water droplet grows to a certain size. FIG. 1 is a diagram schematically showing water droplets in such a state. In FIG. 1, the surface 1 is arranged vertically, the water contact angle θu is small on the upper side of the water droplet 2, and the water contact angle θl is large on the lower side of the water droplet 2. That is, it is expressed so that the difference (θl-θu) becomes large. This can be discussed by replacing the water contact angle θu with the receding contact angle θr on the upper side of the water droplet because the water is attracted downward by the weight of the water droplet and the interface of the droplet tends to recede. On the other hand, in the lower part of the water droplet, water is supplied from top to bottom due to the weight of the water droplet, and the interface of the droplet tends to advance. Therefore, the water contact angle θl on the lower side of the water droplet is the advance contact angle θa. This is because it is considered that it can be discussed by replacing it with. As described above, when the water contact angle θu is small on the upper side of the water droplet and the water contact angle θd is large on the lower side of the water droplet, the water accumulated on the lower side is enlarged due to the high water contact angle. The thinned part on the upper side spreads on the surface and attracts water droplets to the surface with a large contact area.

As a result, a phenomenon occurs in which the water droplets do not run down until they grow to a certain size and endure, and then they cannot bear their own weight as bloated water droplets and flow down the surface at once. In other words, under this phenomenon, it can be said that the water droplets do not fall as fine water droplets, but rather tend to spread on the surface. This microscopic phenomenon is caused by the fact that when water droplets are continuously supplied to the surface due to rainfall or water washing from the outside, the gradually enlarged water droplets can continuously flow down while binding to each other. From a microscopic point of view, it is considered that a state as if a uniform water film was formed on the surface could occur. This state can also be described as dynamic hydrophilicity. Through such a phenomenon, bloated water droplets or water films larger than usual are formed. Therefore, in the process of bloating the water droplets adhering to the surface, the contaminated water that elutes or disperses and takes in the dirt on the surface becomes It is thought that the newly supplied water will replace it all at once and wash it away. Under this phenomenon, in the process of enlargement of water droplets adhering to the surface, the surface is statically water-repellent in the first place, so that contaminants such as iron ions that firmly adhere to the hydrophilic surface are also adsorbed. Since it is suppressed and there is enough time to gradually elute the contaminants, not only hydrophobic deposits or contaminants, but also ionic contaminants can be exposed to rainfall or running water. It is thought that it can be easily washed away.

Then, the receding contact angle θr on the surface measured by the dynamic contact angle measurement by the expansion contraction method is 25 ° or less, so that the thinned portion on the upper side of the attached water droplet as shown in FIG. It is considered that the water droplets can be sufficiently spread on the surface to strongly attract the bloated water droplets to the surface with a large contact area, and the self-purifying property can be more effectively exhibited.

According to a more preferred embodiment of the present invention, the self-cleaning member has a contact angle hysteresis Δθ of 80 ° or more and a receding contact angle θr of 25 ° or less even after being exposed outdoors for 6 months. It is preferable to maintain the state. As a result, it is possible to maintain excellent weather resistance and excellent antifouling property for a long time. In the present invention, for "outdoor exposure for 6 months", a 150-hour accelerated acceleration test based on the sunshine carbon arc test of JIS-K-5400 9.8 accelerated weathering test is equivalent to 6 months of exposure. Can be regarded as.

<u style="single">Self-cleaning member surface</u> As long as the surface of the present invention is made of a material capable of realizing a contact angle hysteresis Δθ (= θa-θr) of 80 ° or more, the material and microstructure thereof are not particularly limited.

According to a preferred embodiment of the present invention, high water droplet retention ability on the surface due to contact angle hysteresis of 80 ° or more is realized on a porous surface having an opening having a pore diameter of 0.01 μm to 30 μm. It is considered that this is because the water droplets are trapped in the pores of the porous surface, so that the fine water droplets do not fall as they are, but rather tend to accumulate on the surface and spread easily.

Means for realizing a self-cleaning surface include a mode 1 in which a coating composition is applied to the surface of a base material to form a coating layer, a mode 2 in which a porous surface formed by anodizing is subjected to a water repellent treatment, and other aspects. There is an aspect.

<u style="single">Aspect 1: Realization of self-cleaning surface by coating composition Paint</u> According to a more preferred embodiment of the present invention, the surface of the coating layer of the self-cleaning member is preferably porous, and such a porous surface has 200 or more pores having a diameter of about 5 to about 30 μm. mm²It is more preferable that it is formed at the density of. With such a pore size and number density, water easily penetrates into the pores, and water droplets are strongly trapped in the pores on the porous surface, so that the enlarged water droplets flow down the surface at once. It is possible to more effectively exert the self-purifying property of. The size and number density of such pores can be measured by the particle (circle) shape analysis function of a laser microscope.

According to a preferred embodiment of the present invention, the surface preferably contains a hydrophobic substance as a substrate. As a result, the above-mentioned movement realized on the surface by the contact angle hysteresis of 80 ° or more while ensuring the antifouling function by the conventionally known water-repellent surface by imparting static hydrophobicity to the surface. Can contribute to the hydrophilicity. Specifically, the static water repellency imparted to the surface promotes the tendency that the adhered water droplets do not easily flow down until they grow to a certain size due to the interaction with the pores on the surface. The self-cleaning property against dirt can be improved. Further, since the surface is hydrophobic, it is possible to weaken the interaction with easily water-soluble ionic pollutants contained in iron rust and the like, and improve the self-purification property by running water against this dirt. According to a preferred embodiment of the present invention, it is preferable that the addition of the hydrophobic substance imparts a contact angle of 80 to 130 ° to water on the surface of the coating layer.

As the hydrophobic substance, any substance can be used as long as it exhibits hydrophobicity, but it is preferable to use a hydrophobic resin, and as the hydrophobic resin, acrylic resin, urethane resin, styrene resin, epoxy resin, etc. Examples thereof include silicone resins, fluororesins, and combinations thereof. More preferably, a silicone resin having higher hydrophobicity, a fluororesin, and a combination thereof can be mentioned. Such a hydrophobic resin is preferably given to the surface of the substrate in the form of hydrophobic resin emulsion particles and cured by drying or heating. The "hydrophobic resin emulsion particles" in the present invention are granules in which a partially or completely polymerized hydrophobic resin is dispersed and stabilized in an emulsified state mainly containing an emulsifier in a dispersion medium such as water. Represents an object. As such hydrophobic resin emulsion particles, for example, at least one selected from fluororesin emulsion particles and silicone emulsion particles is used, or it is preferable to use a mixture thereof.

The silicone resin emulsion particles that can be used as the hydrophobic resin are not limited to those obtained by any production method, but those produced by the following production methods can be preferably used. (1) A method of emulsifying an alkoxysilane compound or a partial hydrolysis / condensate thereof with various surfactants to obtain an aqueous emulsion (see, for example, Japanese Patent Application Laid-Open No. 3-200793). (2) A method of forcibly mechanically pulverizing and dispersing a solvent-free solid silicone resin together with a chain silicone compound to obtain an aqueous emulsion (see, for example, Japanese Patent Application Laid-Open No. 7-247434). (3) A method of emulsion-polymerizing a radically polymerizable vinyl monomer in the presence of a water-soluble polymer obtained by hydrolyzing alkoxysilane in water without using a surfactant (for example, JP-A-8-60098). reference). (4) An aqueous emulsion containing a solid silicone resin is obtained by hydrolyzing and condensing an alkoxysilane mixture containing a vinyl-polymerizable alkoxysilane, and a radical-polymerizable vinyl monomer is further added and emulsion-polymerized to form a graft. A method for obtaining a polymer fine particle (solid) emulsion (see, for example, Japanese Patent Application Laid-Open No. 7-196750). (5) A method in which an alkoxysilane is added to an emulsion obtained by emulsion polymerization of a radically polymerizable functional group, hydrolyzed and condensed, and a silicone resin is introduced into the emulsion particles (see, for example, Japanese Patent Application Laid-Open No. 8-3409). (6) A method for preparing an emulsion by emulsion-polymerizing a vinyl polymerizable functional group-containing alkoxysilane together with a radically polymerizable vinyl monomer (see, for example, Japanese Patent Application Laid-Open No. 8-27347).

4-Epoxycyclohexyl) Ethyltriethoxysilane and the like can be mentioned. As the silicone resin emulsion, those obtained by emulsifying and dispersing these silane compound monomers as a hydrolyzate or a polymer by partial hydrolysis by the production method described above can be preferably used.

The fluororesin emulsion particles that can be used as the hydrophobic resin are not limited to those obtained by any production method, and are based on the polymerization mechanism of various methods such as radical polymerization method, cationic polymerization method, and anion polymerization method. , It may be produced by a solution polymerization method, a massive polymerization method, a suspension polymerization method, an emulsion polymerization method or the like. Further, random, alternating, block copolymers based on the above polymerization mechanism, blocks, grafts, star-type polymers and the like whose molecular weight distribution is controlled by applying various living polymerization methods or polymer reactions can be freely selected. Further, after obtaining such a polymer, it is also possible to modify the polymer by various polymer reactions, a method applying energy rays such as radiation and electron beam ultraviolet rays, and the like. Preferred examples of the fluororesin emulsion are polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene. Copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, perfluorocyclopolymer, vinyl ether-fluoroolefin copolymer, vinyl ester-fluoroolefin copolymer, tetrafluoroethylene-vinyl ether copolymer, chlorotrifluoroethylene-vinyl ether copolymer, tetrafluoroethylene urethane bridge Examples thereof include polymer emulsion particles containing a fluoro group such as a body, a tetrafluoroethylene epoxy crosslinked product, a tetrafluoroethylene acrylic crosslinked product, and a tetrafluoroethylene melamine crosslinked product.

According to a preferred embodiment of the present invention, the average particle size of the hydrophobic resin emulsion particles is preferably 80 nm to 2000 nm, more preferably 80 nm to 1000 nm, and further preferably 100 nm to 1000 nm. As a result, a crosslinked structure can be effectively formed, surface irregularities and pores in the formed crosslinked structure can be prevented from becoming too small, and sufficient porosity can be ensured, thereby improving antifouling property. Can be made to. For example, in a preferred embodiment in which a whiskers described later are used in combination, when the average particle size of the hydrophobic emulsion is 80 nm to 2000 nm, it can be rapidly adsorbed around the whiskers to form a crosslinked structure, particularly 100 nm to 1000 nm. In the range of, it can be most efficiently adsorbed on the whiskers to form a crosslinked structure. The average particle size of the hydrophobic resin emulsion particles in the present invention is measured using a particle size distribution measuring device for concentrated systems (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. As a method for measuring the average particle size in the present invention, for example, for an emulsion dispersion adjusted to have a solid content of 10% by weight, the average by the cumulant method is obtained by obtaining a quadratic autocorrelation function that can be directly calculated from the time change of the scattering intensity. The particle size (fluodynamic diameter) is used as the average particle size. Incidentally, the average particle size of the hydrophobic resin emulsion particles in the present invention is calculated by the particle size including the emulsifier layer when an emulsifier is contained due to the nature of the emulsion.

According to a preferred embodiment of the present invention, the coating layer preferably further contains whiskers, whereby innumerable pores having openings on the surface of the coating layer can be efficiently formed, and self-purification can be performed. The sex can be improved. The "whisker" in the present invention is a rod-shaped body, a fibrous body, or the like having an aspect ratio having a minor axis and a major axis. According to a particularly preferred embodiment of the present invention, the whiskers are used in combination with a hydrophobic resin, that is, the coating layer preferably contains the hydrophobic resin and the whiskers. The hydrophobic resin (hydrophobic emulsion resin particles before curing) acts as a fixing linker for the whiskers to form a porous structure including irregularities on the surface of the composite material, for example, in the case of rainfall, rainwater. However, in the case of washing with water, when water droplets are supplied from the outside, it is conceivable that water easily enters and exits near the surface of the composite material. Due to this peculiar action, it is possible to have a property of having a large affinity with water while having a hydrophobic surface, and the adhesion strength with water at the interface is increased, so that the contact angle hysteresis is increased. Due to this excellent surface property, hydrophobic deposits or contaminants adhering to the surface of the composite can be easily washed away. Furthermore, by using hydrophobic resin emulsion particles as a linker, the surface of the composite material can be made hydrophobic, so that the interaction with ionic pollutants contained in iron rust and the like is weakened, and water droplets supplied from the outside as described above are weakened. Therefore, it can be easily washed away. In the present invention, a member having a surface having a contact angle hysteresis as described above will have adherent deposits and / or contaminants when the surface is exposed to water application by rainfall or water washing for a long period of time. It will be washed away by raindrops, will be easier to wash with water, and will be cleaned with just a rinsing or simple wiping.

The whiskers that can be used in the present invention may be any whiskers that combine with hydrophobic resin emulsion particles in the coating layer to form a structure, and preferred examples include metal oxide whiskers, metal salt whiskers, and metal salt whiskers. A mixture thereof is mentioned, and a more preferable example is potassium titanate (K) from the viewpoint that high weather resistance of the composite material can be expected.₂Ti₄O₉, K₂Ti₈O₁₇Etc.), calcium carbonate, sepiolite, wollastonite, titanium oxide (rutile type, TiO)₂-B etc.), zinc oxide, inorganic whiskers such as aluminum borate, and more preferably potassium titanate whiskers, aluminum borate whiskers, calcium carbonate whiskers, and titanium oxide whiskers.

According to a preferred embodiment of the present invention, the aspect ratio represented by the average minor axis / average major axis of the whiskers is preferably 5 to 100, more preferably 10 to 50. According to this aspect, a three-dimensional crosslinked structure is efficiently formed by eliminating the risk of cracks and the like, and surface irregularities and pores are narrowed due to an excessive number of emulsion particles adsorbed per whisker. It is possible to prevent the conversion and improve the self-purification property. The minor axis and major axis of the whiskers in the present invention can be determined by observing 50 whiskers with a field of view of 1000 times magnification using a scanning electron microscope (S-4100 manufactured by Hitachi, Ltd.). It is obtained by calculating the average value of the major axis.

According to a preferred embodiment of the present invention, the average minor axis of the whiskers is preferably 50 nm to 2000 nm, more preferably 100 nm to 1000 nm. According to this aspect, it is possible to prevent the formation of the crosslinked structure from being poorly formed due to the number of emulsion particles adsorbed per whisker particle being too small, and the crosslinked structure due to the number of emulsion particles adhering to one whisker particle being too large. The surface irregularities and pores inside can be prevented from narrowing, and self-purification can be improved.

According to a preferred embodiment of the present invention, the ratio of the average minor axis of the whiskers to the average particle size of the hydrophobic resin emulsion particles is preferably 0.1 to 5. According to this aspect, it is possible to prevent the formation of the crosslinked structure from being poorly formed due to the number of emulsion particles adsorbed per whisker particle being too small, and the crosslinked structure due to the number of emulsion particles adhering to one whisker particle being too large. Self-purification can be improved by preventing surface irregularities and narrowing of pores inside.

According to a preferred embodiment of the present invention, the weight ratio of the hydrophobic resin to the whiskers is preferably 2 or more and 5.5 or less, more preferably 2 or more and 5 or less, and further preferably 2 or more and 4 or less. Such a weight ratio can be easily realized by using a coating composition in which the solid content weight ratio of the whiskers to the hydrophobic resin emulsion particles is adjusted within the above range at the time of forming the coating layer. In the present specification, the "solid content weight" represents the weight of the remaining heated solid content after heating at 150 ° C. for 5 hours, and the "solid content weight ratio" represents the ratio. According to this aspect, the hydrophobic resin emulsion particles and the whiskers are easily crosslinked three-dimensionally to prevent narrowing of surface irregularities, and the hydrophobicity of the member surface is also ensured, so that the forward contact angle is increased. The contact angle hysteresis due to the decrease can prevent a relative decrease. In addition, it is possible to prevent irregularities and narrowing of pores in the crosslinked structure due to an excessively large ratio of hydrophobic resin emulsion particles on the surface of the member. As a result, the crosslinked structure of the hydrophobic resin emulsion particles and the whiskers can appropriately increase the surface irregularities and pores to improve the self-cleaning property.

According to a preferred embodiment of the present invention, the weight ratio of the whiskers and the hydrophobic resin to the total weight of the coating layer is preferably 0.1 or more and 1 or less, more preferably 0.3 or more and 1.0 or less, and further preferably 0.4 or more. It is 1.0 or less. For such a weight ratio, a coating composition is used in which the ratio of the total weight of the whiskers and the solid content of the hydrophobic resin emulsion particles to the solid content weight of the coating composition is adjusted within the above range when the coating layer is formed. This can be easily realized. According to this aspect, the abundance ratio of the whiskers and the hydrophobic resin emulsion on the surface can be sufficiently increased, and the self-cleaning property is improved.

According to a preferred embodiment of the present invention, the surface can further contain photocatalytic particles. Examples of preferred photocatalytic particles include anatase-type titanium oxide, rutile-type titanium oxide, zinc oxide, tin oxide, ferric oxide, dibismuth trioxide, tungsten trioxide, strontium titanate, and combinations thereof. According to a preferred embodiment of the present invention, the weight ratio of the photocatalytic particles to the total weight of the coating layer is 0.001 to 0. Can be 1. According to a preferred embodiment of the present invention, the coating layer can contain photocatalytic particles. By complementarily containing photocatalytic particles in the self-purifying composite material of the present invention, pollutants due to organic substance decomposition by photocatalytic particles can be removed and harmful gases such as NOx can be removed in an irradiation environment of sunlight or artificial light. Degradability can be expected, and the antifouling property of the self-cleaning member of the present invention can be expected to be further improved. Examples of the photocatalyst particles in the present invention include titanium oxide, zinc oxide, tin oxide, iron oxide, zirconium oxide, tungsten trioxide, chromium oxide, molybdenum oxide, ruthenium oxide, germanium oxide, lead oxide, cadmium oxide, and copper oxide. Particles such as vanadium oxide, niobium oxide, tantalum oxide, manganese oxide, rhodium oxide, ferric oxide, nickel oxide, dibismus trioxide, renium oxide, and strontium titanate can be used. When titanium oxide is used as a photocatalyst, it is preferable to use a crystal type of anatase type, rutile type or brookite type because the photocatalytic activity is the strongest and it is expressed for a long period of time. Further, particles designed to be made to respond to visible light by doping a different element into the crystal structure of titanium oxide can also be used. As the element to be doped in titanium oxide, anionic elements such as nitrogen, sulfur, carbon, fluorine and phosphorus, and cationic elements such as chromium, iron, cobalt and manganese are preferably used. The photocatalytic particles used in the present invention are more preferably anatase-type titanium oxide, rutile-type titanium oxide, zinc oxide, tin oxide, ferric oxide, dibismuth trioxide, tungsten trioxide, and strontium titanate. These may be mixed and used. As the photocatalytic particles of the present invention, anatase-type titanium oxide can be most preferably used.

The average particle size of the photocatalyst particles in the present invention is not particularly limited, but is preferably 5 to 100 nm, and more preferably 10 nm to 50 nm. The "average particle size" referred to here is measured using a particle size distribution measuring device for dense systems (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. As a method for measuring the average particle size in the present invention, for example, for a photocatalyst dispersion adjusted to have a solid content of 10% by weight, the average by the cumulant method is obtained by obtaining a quadratic autocorrelation function that can be directly calculated from the time change of the scattering intensity. It is used as the average particle size by measuring the particle size (hydrodynamic diameter). According to a preferred embodiment of the present invention, the weight ratio of the photocatalytic particles to the total weight of the coating layer (corresponding to the total solid content weight of the coating composition before curing) is preferably 0.1 or less, more preferably 0.05 or less. According to this aspect, even in an environment irradiated with light including ultraviolet rays such as sunlight, the predominant expression of decomposition reaction of organic substances in the coating layer by the photocatalyst is suppressed, and deterioration such as chalking is reduced. However, it can be expected to decompose organic substances in an ultraviolet light irradiation environment. Especially when it is 0.05 or less, the stability of the member is improved even under long-term outdoor exposure.

According to a preferred embodiment of the present invention, the coating layer can further contain hydrophilic inorganic particles. According to this aspect, it can be expected to improve the curability in the coating layer and suppress the microscopic adhesion of hydrophobic stains. Preferred examples of hydrophilic inorganic particles include silica, alumina, zirconia, ceria, and mixtures thereof, with silica being more preferred. According to a preferred embodiment of the present invention, the weight ratio of the hydrophilic inorganic particles to the total weight of the coating layer (corresponding to the total solid content weight of the coating composition before curing) is preferably 0.001 to 0.5. It is more preferably 0.5 or less, still more preferably 0.3 or less. According to this aspect, self-purification can be improved by efficiently preventing the adhesion of hydrophobic stains while preventing the generation of cracks due to an excessive amount of inorganic components contained in the coating layer. It is expected to be possible. The average particle size of the hydrophilic inorganic particles is not particularly limited, but is preferably 3 to 100 nm, and more preferably 5 nm to 50 nm. The "average particle size" referred to here is measured using a particle size distribution measuring device for dense systems (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. As a method for measuring the average particle size in the present invention, for example, for a dispersion of hydrophilic inorganic particles adjusted to a solid content of 10% by weight, a quadratic autocorrelation function that can be directly calculated from the time change of scattering intensity is obtained to obtain a cumulant. It is used as the average particle size by measuring the average particle size (fluodynamic diameter) by the method.

According to a preferred embodiment of the present invention, the coating layer can further contain a color pigment. As a result, it is possible to add a design such as coloring or pattern to the appearance. Color pigments include inorganic pigments, organic pigments, and mixtures thereof. Preferred examples of inorganic pigments are metal oxides such as titanium oxide, zinc flower, red iron oxide, chromium oxide, cobalt blue and iron black, metal hydroxides such as alumina white and yellow iron oxide, and ferrussians such as navy blue. Compounds, lead chromate such as yellow lead, zinc chromate, molybdenum red, sulfides such as zinc sulfide, vermilion, cadmium yellow and cadmium red, sulfates such as selenium compounds, barite and precipitated barium sulfate, heavy Carbonate-based such as calcium carbonate and precipitated calcium carbonate, silicate-based such as hydrous silicate, clay and ultramarine, carbon-based such as carbon black, metal powder-based such as aluminum powder, bronze powder and zinc powder, mica / oxidation Examples include pearl pigments such as titanium. Preferred organic pigments include nitroso pigments such as naphthol green B, nitro pigments such as naphthol S, azo pigments such as resole red, lake red C, fast ero, and naflor red, alkaline blue red, and rhodamine chelate. Examples thereof include condensed polycyclic pigments such as quinacridone red, dioxazine violet, and isoindolinone yellow.

According to a preferred embodiment of the present invention, the film thickness of the coating layer is preferably 1 μm to 1 mm, more preferably 5 μm to 500 μm. According to this aspect, it is easy to form a uniform coating layer by avoiding that the film thickness becomes smaller than the average particle size of the hydrophobic resin emulsion particles and the minor diameter of the whiskers, and cracks are less likely to occur.

<u style="single">Base material</u> The base material used for the self-cleaning member in the present invention is not particularly limited as long as it is a material capable of forming a coating layer, but preferable examples are plastic, metal, glass, ceramic, cement, and organic fiber. , Organic fabrics, painted steel sheets and the like. According to a preferred embodiment of the present invention, the self-cleaning member is preferably used as a building material for an outer wall. For example, by forming a coating layer exhibiting the self-cleaning property of the present invention on a building material base material for an outer wall, when the surface is exposed to rainfall, raindrops wash away deposits or contaminants adhering to the surface. Alternatively, it can be washed with water. Furthermore, when photocatalytic particles are added, further improvement in antifouling property due to organic matter decomposition by sunlight irradiation can be expected. Preferred examples of exterior wall building material substrates are glazed tiles, non-glazed tiles, bricks, crystallized glass, glass blocks, concrete, stones, wood; lightweight cellular concrete plates, asbestos cement calcium silicate plates, precast reinforced concrete plates, asbestos. Cosmetic inorganic building materials in which resin paints such as acrylic resin, urethane resin, polyester, silicone, fluororesin, and acrylic silicone resin are applied to the surface layer of inorganic base materials such as slate boards, pulp cement boards, and plaster board boards; aluminum, stainless steel, Painted steel plate with resin paint such as acrylic resin, urethane resin, polyester, silicone, fluororesin, acrylic silicone resin coated on the surface layer of a metal base material such as steel; plastic plate such as acrylic plate and polycarbonate plate or its coating, etc. Can be mentioned.

<u style="single">Coating composition</u> The self-cleaning member of the present invention can be produced by applying a coating composition to the surface of a base material. The coating composition preferably used for this production comprises the above-mentioned hydrophobic resin emulsion particles, whiskers, a dispersion medium, and optionally various optional components such as photocatalytic particles, hydrophilic inorganic particles, and coloring pigments. Including. As a result, the hydrophobic resin emulsion particles highly dispersed in the dispersion medium are adsorbed on the surface of the whisker, so that the hydrophobic resin emulsion particles can form a highly three-dimensional crosslinked structure with the whisker as a linker. Conceivable. The preferable composition and blending ratio of each component in the coating composition are as described above, and it is preferable that the coating composition is formulated so as to satisfy the above-mentioned suitable solid content weight ratio. The solid content ratio in the coating composition is not particularly limited, but is preferably 0.1% by weight to 80% by weight, and more preferably 10% by weight to 60% by weight.

According to a preferred embodiment of the present invention, water can be preferably used as the dispersion medium. According to this aspect, since the highly dispersibility of the hydrophobic resin emulsion particles is maintained, a uniform crosslinked structure with whiskers can be formed, and there is no adverse effect on the global environment or the human body.

According to a preferred embodiment of the present invention, it is possible to add a film-forming auxiliary to the coating composition in order to improve the film-forming property on the substrate. The film-forming auxiliary is an additive that remains in the coating film even after most of the water is vaporized and has a function of promoting fusion between emulsion particles. Preferred film-forming aids are organic compounds with a boiling point of 100 ° C. or higher, and examples of such organic compounds include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monopropyl ether, and the like. Ethylene glycol ethers such as diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, ethylene glycol ethyl ether acetate, diethylene glycol monobutyl ether acetate; propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, di Propropylene glycol monomethyl ether, Propylene glycol ethers such as dipropylene glycol dimethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, polypropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol diacetate, propylene glycol phenyl ether, etc. Classes; and esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, n-PENTYL PROPIONATE, dibutyl phthalate and the like. Among them, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, which is one of the esters, has a high penetrating ability into the fluororesin emulsion and has an effect of lowering the minimum film forming temperature (MFT). Its use is preferred due to its high price. On the contrary, ethylene glycol ethers are highly toxic to the human body, so their use is not preferable.

The coating composition of the present invention is produced by uniformly dispersing each raw material in the coating composition. This uniform dispersion can be preferably performed by stirring and mixing using a stirrer such as a dissolver, a dispenser, a stirrer, or a shaker.

Method for Manufacturing Self-Purifying Member As described above, the self-cleaning composite material of the present invention can be manufactured by applying a coating composition to a substrate and curing the composition by drying or heating. .. The method for forming the coating composition on the substrate is not particularly limited, and the roller coating method, spray coating method, bar coating method, doctor blade method, dip coating method, spin coating method, tape forming method, casting method, etc. Can be preferably performed using. According to a preferred embodiment of the present invention, the coating film can be dried and cured even at room temperature of about 0 to 40 ° C., and can be applied outdoors. Further, according to another preferred embodiment of the present invention, after the film is formed by the above-mentioned film forming method, in order to accelerate the curing of the coating film, it is heated at a temperature of 10 ° C to 300 ° C to be dried and cured. You may.

According to a preferred embodiment of the present invention, when forming a coating layer on a base material, the base material may be pretreated in order to improve adhesion. Preferred examples of the pretreatment include cleaning, polishing, electrolytic polishing, electrical oxidation, sandblasting, and the like. Further, when the coating layer in the present invention is formed on a building material base material for an outer wall, in order to improve the adhesion to the base material, an undercoating agent to be a primer layer is formed on the base material by a method such as coating. , A coating layer may be formed.

<u style="single">Aspect 2: Water repellent treatment on the porous surface formed by anodizing treatment</u> According to a preferred embodiment of the present invention, a self-cleaning member is produced by using anodizing treatment as a means for forming a porous surface and using a treatment with a water-repellent substance as a means for reducing the surface energy of the surface. Can be done.

The anodic oxidation treatment is performed by immersing aluminum as an electrode in an electrolytic cell using a sulfuric acid or oxalic acid solution as an electrolytic bath, and electrolyzing the aluminum surface with DC or AC to a thickness of 5 to 100 μm. This is a process for obtaining a dense aluminum oxide film. Depending on the conditions, the coating can be grown to a thickness of several mm. Since the oxide film is dissolved by ions such as sulfate roots as it grows depending on the energization time, the grown aluminum oxide film forms cylindrical micropores on the surface on the order of several nm to several hundred nm at high density. There is. In general, the opening diameter of the micropores increases depending on the magnitude of the applied voltage and becomes deeper depending on the energization time. Since it is a porous surface with exposed hydroxyl groups at high density, it is highly hydrophilic and has high surface energy.

As the base material to be anodized, a valve metal such as titanium, niobium, or silicon can be used in addition to the aluminum base material.

The reduction in surface energy means that the surface of the porous base material formed by anodic oxidation is coated with a water-repellent substance to control the surface energy of the base material. A silane coupling agent can be used as a water-repellent substance applicable to lower surface energy.

<u style="single">Aspect 3: Other</u> According to a preferred embodiment of the present invention, a porous surface may be formed on a resin base material which is originally a hydrophobic surface as a means for producing a self-cleaning member. The means for forming the porous surface is not particularly limited, and any means can be used. For example, machining technology using drills and end mills, excimer lasers and CO₂A porous surface may be formed directly on the resin base material by using a laser processing technique using a laser or the like, or a desired porous structure may be formed on the surface of the resin base material by using a molding die.

The resin base material is not particularly limited, and examples thereof include a polycarbonate resin, an acrylic resin, a polyacetal resin, an unsaturated polyester resin, a polystyrene resin, and a polypropylene resin.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

<u style="single">Preparation of coating composition</u> The following materials were prepared as raw materials for the coating composition.<u style="single">Whisker ingredient</u> Potassium titanate whiskers: average minor axis 450 nm, average major axis 15 μm, aspect ratio = 33 Aluminum borate whiskers: average minor axis 750 nm, average major axis 20 μm, aspect ratio = 27 Calcium carbonate whiskers: average minor axis 1000 nm, average major axis 20 μm, aspect ratio = 20 · rutile type titanium oxide whiskers: average minor axis 130 nm, average major axis 1.7 μm, aspect ratio = 13 · TiO₂Type (B) titanium oxide whiskers: average minor axis 450 nm, average major axis 15 μm, aspect ratio = 33<u style="single">Phosphate-like filler component</u> Phosphorus talc: average plate diameter 5 μm, average thickness 0.5 μm<u style="single">Water-based inorganic coloring pigment slurry</u> Pigment slurry (1): Titanium oxide pigment powder milled with water in a ball mill, solid content 50% Pigment slurry (2): Commercially available aqueous titanium oxide pigment slurry: Solid content 65%<u style="single">Hydrophobic resin emulsion particles</u> Aqueous silicone resin emulsion (1): resin content 50%, average particle size 780 nm Aqueous silicone resin emulsion (2): average particle size 760 nm, resin content 50% Aqueous silicone resin emulsion (3): average particle size 365nm, resin content 50% Aqueous silicone resin emulsion (4): average particle size 265nm, resin content 50% Aqueous fluororesin emulsion: average particle size 100nm, resin content 48% <u style="single">Silica sol</u> Aqueous colloidal silica sol (1): average particle size 20 nm, solid content 50% Aqueous colloidal silica sol (2): average particle size 50 nm, solid content 40% Aqueous colloidal silica sol (3): average particle size 85 nm , Solid content 40%<u style="single">Photocatalytic sol</u> Aqueous titanium oxide photocatalytic sol (sol deglued using sodium tripolyphosphate as a dispersant): average particle size 15 nm, solid content 25% silicate-based binder alkali metal silicate: lithium silicate solid content 24%<u style="single">solvent</u> Ion-exchanged water

<u style="single">Formulation example 1</u> Add 26.2 parts by weight of pigment slurry (1), 5.7 parts by weight of potassium titanate whisker powder, 14.4 parts by weight of aqueous silicone resin emulsion (1), and 9.6 parts by weight of aqueous fluororesin emulsion, and stir with a dissolver for 3 hours to make a coating composition. Got The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.57.

<u style="single">Formulation example 2</u> Add 26.2 parts by weight of pigment slurry (1), 5.7 parts by weight of potassium titanate whisker powder, 4.8 parts by weight of aqueous photocatalyst sol, 14.4 parts by weight of aqueous silicone resin emulsion (1), and 9.6 parts by weight of aqueous fluororesin emulsion, and use a dissolver. The mixture was stirred for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.55.

<u style="single">Formulation example 3</u> Add 26.2 parts by weight of pigment slurry (1), 5.7 parts by weight of potassium titanate whisker powder, 16 parts by weight of aqueous colloidal silica sol (1), 14.4 parts by weight of aqueous silicone resin emulsion (1), and 9.6 parts by weight of aqueous fluororesin emulsion. , Stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.46.

<u style="single">Formulation example 4</u> Pigment slurry (1) 26.2 parts by weight of potassium whisker powder 5.7 parts by weight titanate, aqueous rollers Idarushirikazoru (1) 16 parts by weight, 4.8 parts by weight of the aqueous photocatalytic sol, 14.4 parts by weight of aqueous silicone resin emulsion (1), an aqueous fluorine 9.6 parts by weight of the resin emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 5</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (2) 14.4 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 6</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (3) 14.4 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 7</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (4) 14.4 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 8</u> Pigment slurry (1) 26.2 parts by weight, aluminum borate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (1) 14.4 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 9</u> Pigment slurry (1) 26.2 parts by weight, calcium carbonate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (1) 14.4 parts by weight, aqueous fluororesin emulsion 9.6 parts by weight was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 10</u> Pigment slurry (1) 26.2 parts by weight, rutile type titanium oxide whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (1) 14.4 parts by weight, aqueous fluorine 9.6 parts by weight of the resin emulsion was added, and the mixture was stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 11</u> Pigment slurry (1) 26.2 parts by weight, TiO₂Add 5.7 parts by weight of (B) type whisker powder, 16 parts by weight of aqueous colloidal silica sol (1), 4.8 parts by weight of aqueous photocatalyst sol, 14.4 parts by weight of aqueous silicone resin emulsion (1), and 9.6 parts by weight of aqueous fluororesin emulsion. The coating composition was obtained by stirring with a dissolver for 3 hours. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 12</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 2.9 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (1) 14.4 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 4.2. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.40.

<u style="single">Formulation example 13</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (4) 48 parts by weight, aqueous fluororesin 9.6 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 5.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.61.

<u style="single">Formulation example 14</u> Add 26.2 parts by weight of pigment slurry (1), 5.7 parts by weight of potassium titanate whisker powder, 16 parts by weight of aqueous colloidal silica sol (1), 4.8 parts by weight of aqueous photocatalyst sol, and 24 parts by weight of aqueous fluororesin emulsion, and use the dissolver for 3 hours. The mixture was stirred to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 15</u> Add 26.2 parts by weight of pigment slurry (1), 5.7 parts by weight of potassium titanate whisker powder, 16 parts by weight of aqueous colloidal silica sol (1), 4.8 parts by weight of aqueous photocatalyst sol, and 24 parts by weight of aqueous silicone resin emulsion (4). The coating composition was obtained by stirring with a dissolver for 3 hours. The solid content ratio of the water repellent emulsion to the whiskers is 2.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.44.

<u style="single">Formulation example 16 (comparison)</u> Add 26.2 parts by weight of the pigment slurry (1), 16 parts by weight of the aqueous colloidal silica sol (1), 4.8 parts by weight of the aqueous photocatalyst sol, 14.4 parts by weight of the aqueous silicone resin emulsion (1), and 9.6 parts by weight of the aqueous fluororesin emulsion. The mixture was stirred for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 0. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.35.

<u style="single">Formulation example 17 (comparison)</u> Pigment slurry (2) 24.7 parts by weight, potassium titanate whisker powder 7.8 parts by weight, flint talc powder 8.2 parts by weight, aqueous photocatalyst sol 5.7 parts by weight, aqueous silicone resin emulsion (1) 14.7 parts by weight, aqueous fluorine 15.3 parts by weight of the resin emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 1.9. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.46.

<u style="single">Formulation example 18 (comparison)</u> Pigment slurry (1) 56.0 parts by weight, potassium titanate whisker powder 7.0 parts by weight, aqueous colloidal silica sol (1) 14 parts by weight, aqueous photocatalyst sol 30 parts by weight, aqueous silicone resin emulsion (1) 60.2 parts by weight, aqueous fluororesin 25.8 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 6.1. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.50.

<u style="single">Formulation example 19 (comparison)</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (4) 57.6 parts by weight, aqueous fluororesin 9.7 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to give a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 5.9. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.63.

<u style="single">Formulation example 20 (comparison)</u> Pigment slurry (1) 26.2 parts by weight, potassium titanate whisker powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (4) 84.0 parts by weight, aqueous fluororesin 9.7 parts by weight of the emulsion was added and stirred with a dissolver for 3 hours to give a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 8.2. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.70.

<u style="single">Formulation example 21 (comparison)</u> Pigment slurry (1) 26.2 parts by weight, talc powder 5.7 parts by weight, aqueous colloidal silica sol (1) 16 parts by weight, aqueous photocatalyst sol 4.8 parts by weight, aqueous silicone resin emulsion (1) 14.4 parts by weight, aqueous fluororesin emulsion 9.6 parts by weight Parts were added and stirred with a dissolver for 3 hours to obtain a coating composition. The solid content ratio of the water repellent emulsion to the whiskers is 0. The ratio of the total solid content weight of the emulsion and whiskers to the total solid content of the coating composition is 0.35.

<u style="single">Formulation example 22 (comparison)</u> For the purpose of producing a photocatalyst superhydrophilic coating film, 100 parts by weight of an aqueous photocatalyst sol was used as a coating composition.

<u style="single">Formulation example 23 (comparison)</u> To 98.8 parts by weight of ion-exchanged water, 0.25 parts by weight of aqueous colloidal silica sol (1), 0.30 parts by weight of aqueous colloidal silica sol (2), 0.25 parts by weight of aqueous colloidal silica sol (3), and 0.40 parts by weight of alkali metal silicate were added by a stirrer. The mixture was stirred for 1 hour to obtain a coating composition.

<u style="single">Formulation example 24 (comparison)</u> A commercially available acrylic hydrophilic coating agent that forms a smooth and highly transparent film and has a water contact angle of less than 10 ° on the surface of the film.

<u style="single">Formulation example 25 (comparison)</u> A commercially available acrylic silicone-based water-repellent coating agent that forms a smooth and highly transparent film and has a water contact angle of more than 90 ° on the surface of the film.

<u style="single">Preparation of Examples 1 to 15 and Comparative Examples 1 to 7.</u> For each of the coating compositions described in Formulation Examples 1 to 21, a mending tape (tape thickness 63 μm) manufactured by Sumitomo 3M Ltd. was attached to both sides of the long side of the aluminum plate on an aluminum plate cut to 50 mm × 100 mm. The coating composition was applied by an applicator, dried and cured at a temperature of 23 ° C. and a humidity of 50% RH for 1 week to prepare a 40 mm × 100 mm composite material. The average value of the film thicknesses at any five points on the fracture surface obtained by scanning electron microscope observation was about 30 μm. The composite materials obtained from the coating compositions described in Formulation Examples 1 to 15 were designated as Examples 1 to 15, respectively. The composite materials obtained from the coating compositions described in Formulation Examples 16 to 21 were designated as Comparative Examples 1 to 6, respectively.

<u style="single">Preparation of Comparative Example 7</u> Regarding the coating composition described in Formulation Example 22, 1 ml of the coating composition was dropped onto an aluminum plate cut into 50 mm × 100 mm, and the mixture was rotated at 2000 rpm for 10 seconds with a spin coater to apply the coating, temperature 23 ° C, humidity 50%. After drying and curing with RH for 1 week, a composite material of 50 mm × 100 mm was prepared and used as Comparative Example 7. The average value of the film thicknesses at any five points on the fracture surface obtained by scanning electron microscope observation was about 1 μm.

<u style="single">Preparation of Comparative Example 8</u> The coating composition described in Formulation Example 23 was flow-coated on a soda glass plate cut into 50 mm × 100 mm, dried at a temperature of 23 ° C and a humidity of 50% RH for 16 hours, and then dried in the air at 300 ° C for 30 minutes. Was fired to prepare a composite material, which was used as Comparative Example 8.

<u style="single">Preparation of Comparative Example 9</u> The coating agent described in Formulation Example 24 was flow-coated on a soda glass plate cut into 50 mm × 100 mm to prepare a composite material, which was used as Comparative Example 9.

<u style="single">Preparation of Comparative Example 10</u> The coating agent described in Formulation Example 25 is flow-coated on a soda glass plate cut into 50 mm × 100 mm, dried at a temperature of 23 ° C and a humidity of 50% RH for 16 hours, and then dried in the air at 150 ° C for 2 hours. Was dried by heating to prepare a composite material, which was used as Comparative Example 10.

<u style="single">Preparation of Example 16</u> An aluminum plate cut into 30 mm × 60 mm was applied to a voltage of 100 V for 2 minutes in a 2.7% oxalic acid bath, and then immersed in a 5% aqueous phosphoric acid solution for 1 hour. After washing with distilled water, the aluminum plate dried in the air at 80 ° C for 1 hour is immersed in a 0.1% toluene solution of octadecyltriethoxysilane at 50 ° C for 4 hours, washed with toluene and ethanol, and then in the air. , 80 ° C. was dried for 1 hour to prepare a composite material, which was used as Example 17. The surface image observed by the scanning electron microscope was porous, and columnar pores having an opening diameter of about 0.1 μm occupied a region of 50% of the entire visual field in terms of area ratio. The depth of the columnar pores obtained from the cross-sectional observation image was about 2 μm.

<u style="single">Evaluation 1: Measurement of dynamic contact angle</u> The surface of the members of Examples 1 to 16 and Comparative Examples 1 to 10 was measured by the expansion contraction method using an automatic contact angle measuring device (OCA20 manufactured by Eiko Seiki Co., Ltd.), and the forward contact angle of the test piece with respect to water droplets and the forward contact angle with respect to water droplets were measured. The receding contact angle and its contact angle hysteresis were measured. As the measurement conditions for the dynamic contact angle measurement by the expansion / contraction method in the present invention, the injection / suction rate of the water droplet to be expanded / contracted on the substrate was 20 μL / s, and the maximum injection amount was 40 μL. A 500 μL microsyringe (DS500 / GT manufactured by Hamilton) is used as the syringe used when injecting water droplets, and a 90 ° cut tip with an outer diameter of 0.1 mm and a needle hole diameter of 0.05 mm is used as the needle to be connected to the syringe. Stainless needle (SNS021 / 011 manufactured by Data physics) was used. The results obtained are shown in Table 1.

<u style="single">Evaluation 2: Weather resistance test</u> The accelerated weather resistance of the members of Example 4 was evaluated based on JIS-K-5400 "9.8 Accelerated weather resistance test sunshine carbon arc test". After a 150-hour accelerated test equivalent to 6 months of exposure, the water contact angle was examined by dynamic contact angle measurement in the same manner as in Evaluation 1. As a result, θa = 123.7 °, θr = 19.6 °, and Δθ = 104.1 °, and the initial wettability was maintained even after the weather resistance test.

<u style="single">Evaluation 3: Carbon contamination test</u> For the members on the surface of the members of Examples 1 to 16 and Comparative Examples 1 to 10, an aqueous dispersion of hydrophobic carbon black (solid content 1%) was sprayed 10 times on the surface of the members, and the temperature was 23 ° C. , Dry at 50% RH for 2 hours. The degree of carbon adhesion to the surface of the coating film after drying was visually evaluated for contamination. The evaluation indexes of the test were as follows. A: The carbon adhesion marks were not noticeable at all. B: Carbon adhesion was not noticeable. C: Carbon adhesion was noticeable. The results obtained are shown in Table 1.

<u style="single">Evaluation 4: Rust contamination test</u> The coating compositions of each formulation of Formulation Examples 1 to 22 were applied onto the primed aluminum substrate, and dried and cured at room temperature for 1 week. On the test piece thus obtained, a sample in which an iron kugi (length 4 cm) whose surface was oxidized by immersing it in a 1% nitric acid aqueous solution for 1 hour in advance was attached outdoors (Chigasaki City, Kanagawa Prefecture) 2 Exposed for months. After the exposure, the state of adhesion of the rust generated and flowing down the coating film surface to the surface was visually judged. The evaluation indexes of the test were as follows. A: No rust marks were noticeable. B: Rust adhesion was not noticeable. C: Rust was noticeable. The results obtained are shown in Table 1.

<u style="single">Evaluation 5: Measurement of pore size and pore number density</u>By observing the surface of the porous surfaces of Examples 1, 4, 9, and 10 with a three-dimensional laser microscope (VF8710 manufactured by KEYENCE CORPORATION) and using the particle (circle) shape analysis function, the pore size and fineness The number of holes density was calculated. Independent pores with a diameter of 5 to 30 μm in circular equivalent are 1 mm²It was observed at densities of 917, 348, 312, and 220, respectively. On the other hand, in Comparative Example 2, independent pores having a diameter of 5 to 30 μm in terms of a circle are 1 mm.²It was observed at a density of 91 per per.

<u style="single">Evaluation 6: Measurement of static contact angle with water</u> The static contact angle of the member surfaces of Examples 1 to 16 and Comparative Examples 1 to 10 with respect to water was measured by adhering 5 μL of water droplets using an automatic contact angle measuring device (OCA20 manufactured by Eiko Seiki Co., Ltd.). It was measured by the Cecil method, and the value after standing for 30 seconds after adhering water droplets was taken as the static contact angle. The results are shown in Table 1. As a result, it was confirmed that the surfaces of the measured members, except for Comparative Examples 7, 8 and 9, had a contact angle with water of 80 to 130 °.

<tables num="1"><img file="JP2008223003A_D0001.tif" /></tables>

<u style="single">Evaluation 7: Water stain contamination test</u> The degree of contamination due to water stain adhesion was visually evaluated on the surface of the members of Examples 1, 3, 4, 8, 16 and Comparative Examples 2, 8, 9, and 10 after repeated spraying and drying with tap water for 2 months. .. The evaluation indexes are as follows. A: When the surface of the member has hardly changed compared to the start of the test AC: Ring-shaped or streaky scale formation is observed on the surface of the member C The results obtained are shown in Table 2.

<u style="single">Evaluation 8: Silicon sealant contamination test</u> Two composite materials of Examples 3, 4, 8, 16 and Comparative Examples 1, 8, 9, and 10 were fixed at intervals of 0.5 cm, and a one-component silicone sealant (Cemedine 8000) was injected between the test pieces. .. After injecting the sealant, it was dried at a temperature of 25 ° C. and a humidity of 50% RH for 16 hours, and then sprayed with distilled water and dried for 2 hours were repeated 5 times. The degree of surface contamination by the hydrophobic component transferred from the silicone sealant was determined by the water film forming property by distilled water spray and further evaluation 3: carbon contamination test. The evaluation indexes are as follows. Water film formability A: Water film formed on the entire surface of the member B: Part of the surface of the member repels water C: Water repellent on the entire surface of the member Carbon adhesion A: Traces of carbon adhesion B: Carbon adhesion was not noticeable C: Carbon adhesion was noticeable Table 2 shows the results.

<tables num="2"><img file="JP2008223003A_D0002.tif" /></tables>

As can be seen from the above results, composite materials having a contact angle hysteresis Δθ (= θa-θr) of 80 ° or more are similar to hydrophobic stains caused by carbon black, iron rust contamination, water stain contamination, and silicon seal contamination. It can be seen that it has excellent stain resistance against various ionic pollutants or reactive pollutants. In addition, as a result of the sunshine carbon arc type test, it was found that the member maintains the above characteristics and has excellent weather resistance even after the treatment equivalent to 6 months of outdoor exposure.

<figref num="1">It is a schematic diagram explaining the water drop adhering to the surface of the self-cleaning member of this invention.</figref>