Water-repellent coating film and article

Abstract

The invention relates to a water-repellent film and an article. The water-repellent coating is provided with spherical particles, inorganic fine particles having an average particle diameter less than the average particle diameter of the spherical particles, inorganic nanoparticles having fine irregularities formed on the surface thereof, a water-repellent resin having water repellency, and an oil.

Description

Technical Field

[0001] The present disclosure relates to a water-repellent film and an article having water repellency. Background Art

[0002] Water-repellent coatings and articles having such coatings are known. A water-repellent surface having fine irregularities exhibits super-water repellency. Such a water-repellent surface has the effect of inhibiting the adhesion of water, ice, and snow. By applying a coating having such a water-repellent surface to outdoor equipment, it is possible to inhibit obstructions caused by the adhesion of water, ice, and snow. Such obstructions include, for example, signal degradation at antennas, induction of short circuits in insulating devices, or fixation of movable parts. Furthermore, this also reduces the hassle of removing adhered ice and snow.

[0003] Patent Document 1 discloses a coating comprising fluororesin powder or inorganic fine powder with a hydrophobic surface treatment, a silicone resin binder, and silicone oil. Patent Document 2 discloses a water-repellent coating comprising silicone and a water-repellent fluororesin. Patent Document 3 also discloses a water-repellent coating having excellent abrasion resistance and comprising a primer layer composed of spherical particles and a base resin, and a top layer composed of inorganic nanoparticles and a water-repellent resin.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-26844

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 10-316820

[0008] Patent Document 3: Japanese Patent No. 6180698 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, with regard to the water-repellent film disclosed in Patent Document 1, super water repellency is manifested by covering the concavo-convex of the inorganic fine powder with silicone oil. Therefore, due to the silicone oil on the surface, dirt is easily generated, and the water repellency is reduced. In addition, with regard to the film disclosed in Patent Document 2, due to the characteristics of the components, the super water repellency is easily reduced due to friction. With regard to the film disclosed in Patent Document 3, although the performance reduction caused by friction is suppressed, the strong stimulation and lightning strikes generated by the impact of objects, the discharge generated in the case of being used in insulating equipment, etc., may cause a local reduction in super water repellency. With regard to the local reduction in super water repellency, although the influence on the suppression of snow accumulation is small, the reduced portion may become a starting point and cause the deterioration to expand, or may easily cause surface discharge, etc.

[0011] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a water-repellent film and an article that are less susceptible to degradation due to friction and maintain initial performance even if localized reduction in super water repellency occurs.

[0012] Means for solving problems

[0013] The water-repellent film according to the present disclosure includes spherical particles, inorganic fine particles having an average particle size smaller than the average particle size of the spherical particles, inorganic nanoparticles having fine irregularities formed on the surface, a water-repellent resin, and oil.

[0014] Effects of the Invention

[0015] According to the present disclosure, the water-repellent film contains oil, and even if the super water-repellency is partially reduced due to the penetration of the oil, the initial performance is maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view showing a water-repellent coating film according to a comparative example.

[0017] Figure 2 It is a cross-sectional view showing the water-repellent coating film according to the first embodiment.

[0018] Figure 3 It is a cross-sectional view showing a water-repellent coating film according to the second embodiment.

[0019] Figure 4 It is a cross-sectional view showing a water-repellent coating film according to the third embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments of the water-repellent film and article disclosed herein will be described with reference to the accompanying drawings. Figure 1 While explaining. It should be noted that the present disclosure is not limited to the embodiments described below. In addition, the size relationship of each component in the drawings is sometimes different from the actual one. In addition, in the following description, in order to facilitate the understanding of the present disclosure, terms indicating directions are used as appropriate, but they are used to illustrate the present disclosure, and these terms do not limit the present disclosure. As terms indicating directions, for example, "up", "down", "right", "left", "front" or "back" can be listed.

[0021] Implementation method 1.

[0022] Figure 1 1 is a cross-sectional view showing a water-repellent film 100a according to a comparative example. Next, the water-repellent film 100a according to the comparative example will be described. In order to facilitate the understanding of the water-repellent film 100 according to the first embodiment, the water-repellent film 100a according to the comparative example will be described first. Figure 1 As shown, the water-repellent film 100a that the comparative example relates to has a primer layer 2 and a top coat layer 3 formed in a manner covering the primer layer 2. The primer layer 2 has spherical particles 5, a base resin 6, and inorganic particles 7. The top coat layer 3 has inorganic nanoparticles 11 and a water-repellent resin 12. The spherical particles 5 of the primer layer 2 form concavo-convexity in the primer layer 2. The concavo-convexity of the primer layer 2 forms concavo-convexity on the surface of the top coat layer 3. The water-repellent film 100a is present on the surface by the top coat layer 3 and shows super water repellency. When the water-repellent film 100a is rubbed, although the top coat layer 3 of the upper part of the spherical particles 5 is worn away, since most of the top coat layer 3 remains in the recessed portion, super water repellency can be maintained. However, when the primer layer 2 is destroyed by rubbing with a sharp object, sometimes, due to the exposure of the hydrophilic material contained in the substrate 1 or the film or the hydrophilic material mixed in from the outside, water droplets become easy to adhere to.

[0023] In addition, between the spherical particles 5 of primer layer 2 and the base resin 6 or between inorganic particles 7 and the base resin 6, sometimes produce tiny space 9. Even if under the situation that produces tiny space 9, owing to forming topcoat layer 3 on the upper surface of primer layer 2, by the concavo-convex of primer layer 2 and the water-repellent resin 12 of topcoat layer 3, as water-repellent film 100a, bring into play function.But, under the situation that forms water-repellent film 100a in high voltage equipment, just with regard to the tiny space 9 that produces between the spherical particles 5 of primer layer 2 and the base resin 6 or between inorganic particles 7 and the base resin 6, can become the starting point that brings out dielectric breakdown.If short circuit occurs due to dielectric breakdown, then the super water repellency loss of the part that short circuit occurs.Except the dielectric breakdown from inside that is caused by space 9, also due to the surface current that is produced because of lightning strike etc., sometimes the hydrophilic material contained in base material 1 or the film or the hydrophilic material that produces because of electric current expose, water droplet easily adheres.

[0024] Figure 2 1 is a cross-sectional view showing a water-repellent film 100 according to Embodiment 1. Figure 2 As shown, the water-repellent film 100 according to the first embodiment includes spherical particles 5, a base resin 6, inorganic fine particles 7, inorganic nanoparticles 11, a water-repellent resin 12, and oil 10. Furthermore, the water-repellent film 100 includes a primer layer 2 and a top coat layer 3. The primer layer 2 includes spherical particles 5, inorganic fine particles 7, oil 10, spherical particles 5, and a base resin 6. The top coat layer 3 includes inorganic nanoparticles 11 and a water-repellent resin 12 and is formed on the primer layer 2.

[0025] In the water-repellent film 100, if the surface of the water-repellent film 100 is rubbed, although the topcoat layer 3 formed on the convex portion of the primer layer 2 is worn, the topcoat layer 3 formed on the concave portion of the primer layer 2 is difficult to wear. If it is repeatedly rubbed and worn, the topcoat layer 3 is worn, forming a state in which the spherical particles 5 are partially exposed, but it is difficult to carry out further wear. Near the exposed area of the spherical particles 5, although there is a tendency that small water droplets easily adhere to, water repellency is maintained. This is because, due to the high smoothness, density and high hardness of the surface of the spherical particles 5, wear resistance is excellent. Even if spherical particles are not used as concave-convex particles, the concave-convex of the primer layer 2 can be formed. When using spherical particles that are not used as concave-convex particles, if the surface of the water-repellent film 100 is rubbed, the friction between the friction object and the concave-convex particles becomes large, and the separation of the concave-convex particles or the peeling of the primer layer 2 occurs easily. In the first embodiment, since the base coat 2 contains oil 10, the adhesion between the concavo-convex particles, the substrate 1, and the base resin 6 is sometimes slightly reduced. When non-spherical particles are used as the concavo-convex particles, the adhesion is reduced, and the particles are easily detached or peeled off. Therefore, in the first embodiment, spherical particles 5 are used. As a result, the particles are less likely to detach or peel off.

[0026] (Spherical particles 5)

[0027] The spherical particles 5 have an average particle size of 2 μm or more and 50 μm or less. It should be noted that the spherical particles 5 preferably have an average particle size of 4 μm or more and 20 μm or less. If the average particle size of the spherical particles 5 is less than 2 μm, the unevenness of the primer layer 2 is too small, and the effect of protecting the top coat 3 cannot be obtained during friction. On the other hand, if the average particle size of the spherical particles 5 exceeds 50 μm, the unevenness of the primer layer 2 is too large, and problems such as foreign matter clogging the concave parts of the top coat 3 occur, and the performance as a water-repellent film 100 cannot be exerted. It should be noted that the average particle size of the spherical particles 5 is a value measured by a laser diffraction particle size measuring device.

[0028] The spherical particles 5 are at least one selected from spherical fused silica particles, spherical fused alumina particles, and spherical silicone resin particles. Thus, as the spherical particles 5, general spherical fused silica particles and spherical fused alumina particles can be used. It should be noted that by using products that have been hydrophobized by treating the surfaces of these particles with a silanizing agent, a silane coupling agent, etc., the wear resistance can be further improved. By using spherical fused silica particles and spherical fused alumina particles that have been hydrophobized, the water repellency of the surface exposed during wear is improved, which can improve the effect of maintaining water repellency. In particular, hydrophobization is effective for spherical fused silica particles. In addition, as a result, it is also easy to be compatible with the oil 10, and it is difficult to generate a gap 9 between the spherical particles 5 and the base resin 6.

[0029] As mentioned above, spherical silicone resin particles can also be used as spherical particles 5. Spherical silicone resin particles have excellent water repellency, so the surface exposed after wear also has water repellency, making it easy to maintain water repellency. Compared with spherical fused silica particles and spherical fused alumina particles, spherical silicone resin particles have the disadvantage of being easily worn by friction with high-hardness materials such as sand and dust. However, they have the advantages of a good feel when rubbed by hand and low frictional resistance during rubbing. In addition, spherical silicone resin particles are easily compatible with oil 10, making it difficult to form voids 9.

[0030] (Base resin 6)

[0031] The base resin 6 may be, for example, polyurethane resin, fluororesin, silicone resin, various polyolefins such as polypropylene and polyethylene, polyvinyl chloride, acrylic resin, methacrylic resin, polystyrene, ABS resin, AS resin, or the like. The base resin 6 may be made of any of these resins alone or in combination of two or more. Polyurethane resin is particularly preferred due to its excellent wear resistance. Fluororesins and silicone resins are also preferred due to their excellent water repellency. To improve adhesion to the substrate 1, a resin into which a substituent or the like is introduced may be used.

[0032] (Inorganic particles 7)

[0033] The inorganic fine particles 7 have an average particle size of 1 μm or more and 15 μm or less, and less than the average particle size of the spherical particles 5. This allows for the formation of smaller irregularities than those formed by the spherical particles 5. By forming such irregularities, an anchoring effect is achieved when the topcoat layer 3 is formed on the undercoat layer 2. Consequently, the topcoat layer 3 is difficult to peel off from the undercoat layer 2, and excellent water repellency is easily maintained even with repeated rubbing.

[0034] In the first embodiment, the inorganic particles 7 are porous particles. Examples of porous particles include calcium silicate particles such as silica gel, precipitated silica, xonotlite, and tobermorite, alumina hydrate particles such as boehmite, and lime-based particles such as quicklime and slaked lime, which have been made porous. These porous particles 7 may be used alone or in combination. In particular, silica gel and precipitated silica are preferred because they have moderate strength and exhibit good dispersibility in the primer layer 2.

[0035] Inorganic particles 7 are generally hydrophilic, so it is preferred to use a product that has been hydrophobized on the surface. With regard to the method for hydrophobization, methods such as making silanizing agents, silane coupling agents, etc. such as hexamethyldisilazane react with inorganic particles 7 can be listed. By making the surface hydrophobization of inorganic particles 7, even if the surface is worn due to friction, hydrophobicity is also difficult to further reduce. In addition, it is also preferred to dry by mixing the inorganic particles 7 as porous particles with a solution of fluororesin or organosilicon resin, impregnating fluororesin or organosilicon resin in the inside of the inorganic particles 7 as porous particles. By using the porous particles that make fluororesin or organosilicon resin impregnation, i.e., inorganic particles 7, even if the surface of the inorganic particles 7 as porous particles is worn due to friction, water repellency is also difficult to reduce.

[0036] As for the inorganic particles 7 as porous particles, since they are porous, they are easily broken when worn, and the wear suppression effect produced by the spherical particles 5 and the characteristics of the flatness of the worn surface are not affected. In addition, the water-repellent resin 12 of the topcoat layer 3 is easily attached to the broken surface of the inorganic particles 7 as porous particles, so that high water repellency is maintained. If the average particle size of the inorganic particles 7 is less than 1 μm, the worn surface is sometimes easily hydrophilized. On the other hand, if the average particle size of the inorganic particles 7 exceeds 15 μm, a large hydrophilic surface is generated when broken, and water is sometimes easily attached. It should be noted that the average particle size of the inorganic particles 7 is a value measured by a laser diffraction particle size distribution measuring device.

[0037] When inorganic particles 7 are porous particles, there is the effect of keeping oil 10 in the gap between particles in the pore inside of the particle, in the particle of non-porousization. With regard to oil 10, by mixing with base resin 6, the strength of resin might be reduced. In addition, if oil 10 is excessively present at the interface between base resin 6 and spherical particles 5 or base material 1, adhesion might be reduced, and the wear resistance of film is reduced. In addition, it might ooze out at the film surface and become the reason for dust attachment. With regard to present embodiment 1, owing to oil 10 being remained on the inside or the gap of inorganic particles 7, the generation of above-mentioned problem is therefore suppressed.

[0038] (Oil 10)

[0039] The oil 10 is impregnated in the inorganic particles 7. When the oil 10 is retained inside or in the gaps between the inorganic particles 7, the oil 10 has a higher degree of freedom as a liquid than when it is mixed with the base resin 6 or when it is thinly present at the interface between the base resin 6 and the spherical particles 5 or the substrate 1. Furthermore, if the base coat 2 has a hydrophilic surface due to damage caused by abrasion or short circuiting, the oil 10 can effectively diffuse and render the hydrophilic surface water-repellent.

[0040] The oil 10 is, for example, silicone oil or fluoro oil. Examples of silicone oil include dimethyl silicone oil, amino-modified silicone oil, alkyl-modified silicone oil, epoxy-modified silicone oil, and higher fatty acid-modified silicone oil. Examples of fluoro oil include perfluoropolyether (PFPE) and polychlorotrifluoroethylene (PCTFE).

[0041] The oil 10 in the primer layer 2 is preferably present in a weight ratio of 1% to 30% relative to the total weight of the base resin 6 and the inorganic fine particles 7, and more preferably in a weight ratio of 2% to 20%. If the weight ratio of the oil 10 is too low, the gaps 9 formed between the base resin 6 and the spherical particles 5 or between the base resin 6 and the inorganic fine particles 7 may not be filled. On the other hand, if the weight ratio of the oil 10 is too high, excess oil 10 may seep onto the surface of the water-repellent film 100, causing stains and possibly reducing water repellency.

[0042] (Base coat 2)

[0043] With regard to the primer layer 2, a primer layer-forming coating composition containing a base resin 6, spherical particles 5, inorganic particles 7, oil 10, and a solvent capable of solubilizing or emulsifying the base resin 6 is applied to a substrate 1 and formed. With regard to the total amount of the base resin 6, the spherical particles 5, the inorganic particles 7, and the oil 10, it is preferably 3% by mass or more and 60% by mass or less relative to the primer layer-forming coating composition. If the total amount of the base resin 6, the spherical particles 5, the inorganic particles 7, and the oil 10 is less than 3% by mass, the spherical particles 5 become easy to settle, and the handling property of the coating composition is reduced. And then, sometimes the spherical particles 5 cannot be stably fixed in the primer layer 2. On the other hand, if the total amount of the base resin 6, the spherical particles 5, the inorganic particles 7, and the oil 10 exceeds 60% by mass, it is sometimes difficult to uniformly form the primer layer 2.

[0044] The mass ratio of the spherical particles 5 and the base resin 6 in the primer layer 2 is preferably 10% by mass or more and 500% by mass or less, more preferably 30% by mass or more and 200% by mass or less. When the spherical particles 5 are less than 10% by mass, sufficient concavities and convexities cannot be obtained in the primer layer 2, and therefore sufficient water repellency cannot be obtained sometimes. In addition, when the spherical particles 5 are more than 500% by mass, the strength as the primer layer 2 cannot be obtained sometimes.

[0045] The mass ratio of the inorganic fine particles 7 to the base resin 6 in the primer layer 2 is preferably 10% by mass or more and 200% by mass or less, and more preferably 20% by mass or more and 100% by mass or less. If the inorganic fine particles 7 are less than 10% by mass, the peeling-inhibiting effect of the top coat layer 3 may not be sufficiently obtained. If the inorganic fine particles 7 exceed 200% by mass, the strength required for the primer layer 2 may not be obtained.

[0046] In the coating composition for forming the primer layer, in order to improve the intensity of the base resin 6, a cross-linking agent can be added. In addition, in the coating composition for forming the primer layer, in order to improve the coatability, or improve the water repellency of the base resin 6, a general additive can be added. With regard to the coating of the coating composition for forming the primer layer, it is carried out by spraying, brush coating or roller coating etc. With regard to the thickness of the primer layer 2, as average thickness, it is preferably more than 1 / 3 times and less than 5 times the average particle size of the spherical particles 5. If the thickness of the primer layer 2 is less than 1 / 3 times the average particle size of the spherical particles 5, sufficient wear resistance can not be obtained sometimes. On the other hand, if the thickness of the primer layer 2 exceeds 5 times the average particle size of the spherical particles 5, the intensity of the primer layer 2 is reduced sometimes, or the appearance variation of the water repellent film 100 is poor.

[0047] (Inorganic Nanoparticles 11)

[0048] The inorganic nanoparticles 11 are silicon dioxide, aluminum oxide, zirconium oxide or titanium dioxide. The surface of the inorganic nanoparticles 11 is generally hydrophilic, so it is preferred to use a product that has been subjected to a hydrophobic treatment on the surface. As for the method of hydrophobic treatment, there can be cited a method of reacting a silanizing agent such as hexamethyldisilazane, a silane coupling agent, etc. with the inorganic nanoparticles 11. In this case, since highly stable hydrophobicity is obtained, it is preferred. In addition, as for the method of hydrophobic treatment, there can also be cited a method of mixing an organic silicon compound or a fluorocarbon compound having a low molecular weight compared to the water-repellent resin 12 with the inorganic nanoparticles 11 and adsorbing it on the surface. It is also preferred to use a method of reducing the hydrophilicity by heat treatment instead of the hydrophobic treatment of the inorganic nanoparticles 11. By heating the inorganic nanoparticles 11 to above 150°C, preferably above 300°C, the hydrophilicity is reduced, and the water repellency of the topcoat layer 3 is easily manifested.

[0049] The average particle size of the primary particles of the inorganic nanoparticles 11 is more than 2nm and less than 20nm, preferably more than 5nm and less than 15nm. If the average particle size of the primary particle size of the inorganic nanoparticles 11 is less than 2nm, the preparation of the coating composition for topcoat formation becomes difficult, and the water repellency of the water-repellent film 100 becomes insufficient. On the other hand, if the average particle size of the primary particles of the inorganic nanoparticles 11 exceeds 20nm, the water repellency of the water-repellent film 100 becomes insufficient, and if repeatedly rubbed, the water repellency is easily lost. It should be noted that the average particle size of the inorganic nanoparticles 11 is a value measured using a laser diffraction particle size distribution measuring device.

[0050] (Water-repellent resin 12)

[0051] The water-repellent resin 12 is a fluororesin or a silicone resin. Alternatively, the water-repellent resin 12 may be a resin such as an acrylic resin, a urethane resin, or an epoxy resin whose surface is made water-repellent by mixing a fluorochemical additive. Fluorine-based resins and silicone resins are particularly preferred due to their excellent water repellency.

[0052] The mass ratio of the inorganic nanoparticles 11 to the water-repellent resin 12 in the topcoat layer 3 is preferably in the range of 40:60 to 95:5, and more preferably in the range of 50:50 to 90:10. If the mass ratio of the inorganic nanoparticles 11 is too high, the topcoat layer 3 may become brittle, resulting in reduced abrasion resistance. On the other hand, if the mass ratio of the water-repellent resin 12 is too high, sufficient water repellency may not be achieved.

[0053] (Top coat 3)

[0054] With regard to topcoat layer 3, by the topcoat layer forming coating composition containing inorganic nanoparticles 11, water-repellent resin 12 and the solvent that can dissolve water-repellent resin 12, be coated on primer layer 2 and form.With regard to the total amount of inorganic nanoparticles 11 and water-repellent resin 12, relative to topcoat layer forming coating composition, preferably more than 0.3 mass % and less than 70 mass %, more preferably more than 0.5 mass % and less than 50 mass %.If the total amount of inorganic nanoparticles 11 and water-repellent resin 12 is less than 0.3 mass %, then topcoat layer 3 attenuates sometimes and can not obtain sufficient water repellency.On the other hand, if the total amount of inorganic nanoparticles 11 and water-repellent resin 12 exceeds 70 mass %, then sometimes easily form the film with many cracks, and topcoat layer 3 becomes easy to peel off.With regard to the preparation of topcoat layer forming coating composition, preferably use liquid dispersion machine such as homogenizer, dissolver, high pressure dispersion device so that inorganic nanoparticles 11 do not remain as large agglomerate. In addition, as the solvent (intermediate), a solvent having a boiling point and viscosity suitable for the coating method can be appropriately selected from solvents capable of dissolving the water-repellent resin 12 .

[0055] The coating composition for forming the top coat layer is applied by spraying, brushing, or roller coating. The top coat layer 3 is preferably prepared to have a film thickness of 100 cm 2 The amount of the water-repellent resin 12 after drying is preferably not less than 0.03 g and not more than 1.2 g. If the amount of the water-repellent resin 12 is less than 0.03 g, the primer layer 2 may be exposed and insufficient water repellency may be achieved. On the other hand, if the amount of the water-repellent resin 12 exceeds 1.2 g, water repellency may be reduced due to friction, or the top coat layer 3 may be easily peeled off.

[0056] As for the top coat 3, even if a separate film is formed, the water repellency is high and the contact angle of water is super water repellency of more than 140°. This is because the fine concavo-convex produced by the inorganic nanoparticles 11 and the water repellency of the water-repellent resin 12. Among them, the contact angle of water is measured by the following method. About 5 μL of water droplets are dropped onto the surface of the water-repellent film 100 from the top of a PTFE (polytetrafluoroethylene)-coated needle with an inner diameter of 0.1 mm, and the contact angle is measured by a contact angle meter (CX-150 type manufactured by Kyowa Interface Chemical Co., Ltd.).

[0057] (Substrate 1)

[0058] The substrate 1 forming the water-repellent film 100 can be used for various components in products requiring water-repellent properties. Examples of products requiring water-repellent properties include outdoor power distribution equipment, electrical facilities, electrical wires, snow removal roofs, heat exchangers for air conditioner outdoor units, solar cells, and radomes. Examples of materials for the substrate 1 include unsaturated polyesters, polyethylene, cross-linked polyethylene, polyvinyl chloride, polyimide, polypropylene, and polystyrene. Examples of materials for the substrate 1 include plastics such as ABS resin, AS resin, fluororesin, and silicone resins, metals such as aluminum and stainless steel, glass, and porcelain.

[0059] By forming such a water-repellent film 100 on the substrate 1, the spherical particles 5 create uneven surfaces, and the fine uneven surfaces of the inorganic nanoparticles 11 and the water-repellent resin 12 provide high water repellency, resulting in a film that easily maintains water repellency through the oil 10. Furthermore, the water-repellent film 100 includes the oil 10. The oil 10 permeates the film, maintaining high water repellency and suppressing the adhesion of water droplets. Therefore, deterioration due to friction is less likely to occur, and even if localized reduction in super water repellency occurs, initial performance is maintained.

[0060] The oil 10 can fill the tiny gaps 9 between the spherical particles 5 and the base resin 6, or between the inorganic particles 7 and the base resin 6. By filling the gaps 9, the starting point of the short circuit can be reduced. In addition, even if the hydrophilic material is exposed due to a short circuit or other reasons, the surface of the exposed hydrophilic material is water-repellent due to the penetration of the oil 10, which can maintain high water repellency and suppress the attachment of water droplets. In addition, if a part is produced that water droplets are easily attached, it is possible that the deteriorated part of the super-water repellency will expand due to the attachment of pollutants, or that a short circuit will easily occur again due to the attachment of water droplets. However, with respect to the water-repellent film 100 involved in this embodiment 1, the attachment of water droplets is suppressed due to the oil 10. Therefore, it is possible to suppress the deteriorated part of the super-water repellency from expanding due to the attachment of pollutants, or that a short circuit will easily occur again due to the attachment of water droplets. In addition, with respect to the water-repellent film 100 involved in this embodiment 1, it is suitable for use because it is formed on various articles.

[0061] Implementation method 2.

[0062] Figure 3 This is a cross-sectional view showing a water-repellent coating 200 according to Embodiment 2. Embodiment 2 differs from Embodiment 1 in that the inorganic fine particles 207 are fluorine-based resin particles. In Embodiment 2, portions common to those in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted. The following description focuses on the differences from Embodiment 1.

[0063] Fluororesin particles are soft and easily stretched due to friction. If the undercoat layer 2 is worn and the inorganic particles 207 begin to be exposed, the fluororesin particles are stretched to the worn surface due to friction, giving the worn surface a high water repellency. In this way, while giving the worn surface a high water repellency, the topcoat layer 3 does not peel off and remains outside the worn surface. Therefore, even if the surface is worn, the water repellency is difficult to further reduce. As in the second embodiment, when fluororesin particles are used as the inorganic particles 207, the oil 10 is more preferably fluorinated oil. Fluororesin particles are easily compatible with fluorinated oil, making it more difficult to form voids 9.

[0064] The inorganic particles 207 are fluororesin particles having an average particle size of 0.05 μm or more and 15 μm or less. By using fluororesin particles having an average particle size smaller than that of the spherical particles 5, it is possible to form unevenness smaller than that formed by the spherical particles 5. Fluororesin particles are easily stretched by friction, which does not affect the wear suppression effect produced by the spherical particles 5 and the characteristics of ensuring the flatness of the wear surface. If the average particle size of the inorganic particles 207 is less than 0.05 μm, the strength of the primer layer 2 is sometimes reduced, or the adhesion between the substrate 1 and the primer layer 2 is reduced, and the primer layer 2 is easily worn or peeled off. On the other hand, if the average particle size of the inorganic particles 207 exceeds 15 μm, the strength of the primer layer 2 is sometimes reduced. It should be noted that the particle size of the fluororesin particles is a value measured by a laser diffraction particle size distribution measuring device. Among them, with respect to the fluororesin particles, the primary particles can have an average particle size of 0.05 μm or more and 15 μm or less and less than the average particle size of the spherical particles 5. The fluororesin particles may have a secondary particle size (aggregates of primary particles having an average particle size of several tens to several hundreds of nm) of 0.05 μm to 15 μm inclusive and less than the average particle size of the spherical particles 5 .

[0065] The content of the inorganic fine particles 207 in the primer layer 2 is preferably 5% by mass or more and 100% by mass or less relative to the content of the spherical particles 5. If the content of the inorganic fine particles 207 is less than 5% by mass, the effect of forming fine irregularities is small, and the peeling-inhibiting effect of the top coat layer 3 may not be obtained. On the other hand, if the content of the inorganic fine particles 207 exceeds 100% by mass, the primer layer 2 may become soft and the wear resistance may be reduced.

[0066] With regard to the mass ratio of the spherical particles 5 and the base resin 6 in the primer layer 2, it is preferably more than 10 mass % and less than 500 mass %, more preferably more than 30 mass % and less than 200 mass %. When the spherical particles 5 are less than 10 mass %, since the primer layer 2 can not obtain sufficient concavo-convexity, sufficient water repellency can not be obtained sometimes. In addition, when the spherical particles 5 are more than 500 mass %, the strength as the primer layer 2 can not be obtained sometimes.

[0067] The mass ratio of the oil 10 to the total mass of the base resin 6 and the fluororesin particles in the primer layer 2 is preferably 1% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 20% by mass or less. If the mass ratio of the oil 10 is too low, the gaps 9 formed between the base resin 6 and the spherical particles 5 or between the base resin 6 and the fluororesin particles may not be filled. On the other hand, if the mass ratio of the oil 10 is too high, excess oil 10 may seep onto the surface of the water-repellent film 200, causing dirt and reducing water repellency.

[0068] The primer layer 2 in the water-repellent film 200 is formed by applying a primer layer-forming coating composition containing a base resin 6, spherical particles 5, fluororesin particles, oil 10, and a solvent capable of solubilizing or emulsifying the base resin 6 to the substrate 1. As a method for adding fluororesin particles to the primer layer-forming coating composition, a method of mixing powdered fluororesin particles with the base resin 6, spherical particles 5, oil 10, and solvent can be cited. Alternatively, a method of mixing a dispersion of fluororesin particles with the base resin 6, spherical particles 5, oil 10, and solvent can be cited.

[0069] With regard to the total amount of base resin 6, spherical particles 5, fluororesin particles and oil 10, relative to the bottom coating layer, it is preferably more than 3 mass % and less than 65 mass % to form a coating composition. If the total amount of base resin 6, spherical particles 5, fluororesin particles and oil 10 is less than 3 mass %, the spherical particles 5 are easily sedimented, the handling property of the coating composition is reduced, and sometimes the spherical particles 5 can not be stably fixed in the bottom coating layer 2. On the other hand, if the total amount of base resin 6, spherical particles 5, fluororesin particles and oil 10 exceeds 65 mass %, it is sometimes difficult to evenly form the bottom coating layer 2. In the bottom coating layer, in order to improve the intensity of the base resin 6, a crosslinking agent can be added. In addition, in the bottom coating layer, in order to improve the coatability, or improve the water repellency of the base resin 6, a general additive can be added.

[0070] By forming such a water-repellent film 200 on substrate 1, the concavo-convex produced by spherical particles 5 is formed, and high water repellency is manifested by the fine concavo-convex of inorganic nanoparticles 11 and water-repellent resin 12, it is possible to obtain a film that is easy to maintain water repellency by oil 10. In present embodiment 2, the water-repellent film has oil 10. It is possible to maintain high water repellency by being impregnated by oil 10, and in addition, water droplet adhesion is suppressed. Therefore, it is difficult to cause the deterioration by friction, even if a local super-water repellent reduction occurs, the performance in the initial stage is maintained. In addition, in primer layer 2, by containing fluororesin particles as inorganic particles 207 with specific average particle size, concavo-convex is formed on the surface of primer layer 2 in the same manner as described in embodiment 1, obtaining topcoat layer 3 is difficult to peel off such an effect from primer layer 2. It is explained that the coating method of primer layer formation coating composition, the film thickness of primer layer 2, the composition of topcoat layer 3, the coating method of topcoat layer formation coating composition and the film thickness of topcoat layer 3 are the same as embodiment 1.

[0071] Implementation method 3.

[0072] Figure 41 is a cross-sectional view showing a water-repellent coating 300 according to Embodiment 3. Embodiment 3 differs from Embodiments 1 and 2 in that the water-repellent coating 300 is formed as a single layer. In Embodiment 3, portions common to Embodiments 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. The description will focus on the differences from Embodiments 1 and 2.

[0073] The water-repellent film 300 is composed of spherical particles 5, inorganic fine particles 7, inorganic nanoparticles 11, a water-repellent resin 15, and oil 10. In addition, as the inorganic fine particles 7, porous particles are used.

[0074] (Spherical particles 5)

[0075] The average particle size of the spherical particles 5 contained in the water-repellent film 300 is 2 μm or more and 50 μm or less, preferably 4 μm or more and 20 μm or less. If the average particle size of the spherical particles 5 is less than 2 μm, the unevenness of the water-repellent film 300 becomes excessively small, and the water-repellent film 300 located in the concave portion cannot be protected during friction. On the other hand, if the average particle size of the spherical particles 5 is greater than 50 μm, the unevenness of the water-repellent film 300 becomes excessively large, and problems such as clogging of the concave portion of the water-repellent film 300 by foreign matter occur, and the performance of the water-repellent film 300 can no longer be exerted. It should be noted that the average particle size of the spherical particles 5 is a value measured by a laser diffraction particle size measuring device.

[0076] As the spherical particles 5, it is preferred to use spherical fused silica particles or spherical fused alumina particles whose surfaces have been hydrophobized using a silanizing agent, a silane coupling agent, or the like. Using hydrophobized spherical fused silica particles or spherical fused alumina particles can improve the water repellency of the surface exposed during wear, thereby enhancing the effectiveness of maintaining water repellency. Hydrophobization is particularly effective for spherical fused silica particles. Furthermore, this makes them more compatible with oil 10, making it difficult to form gaps 9 between the spherical particles 5 and the base resin 6.

[0077] Spherical silicone resin particles can be used as spherical particles 5. Spherical silicone resin particles have excellent water repellency, so even the surface exposed after wear is water repellent, making it easier to maintain water repellency. Compared to spherical fused silica particles and spherical fused alumina particles, spherical silicone resin particles have the following disadvantages: they are easily worn by friction with high-hardness materials such as sand and dust. However, they have advantages such as a good feel when rubbed by hand and low frictional resistance. Furthermore, spherical silicone resin particles are easily compatible with oil 10, making it difficult to form voids 9.

[0078] (Inorganic particles 7)

[0079] In the third embodiment, the inorganic particles 7 are porous particles. Examples of porous particles include silica gel, precipitated silica, xonotlite, tobermorite and other calcium silicate particles, boehmite and other alumina hydrate particles, quicklime, slaked lime and other lime-based particles made porous, etc. These porous particles as the inorganic particles 7 can be used alone or in combination of two or more. In particular, silica gel and precipitated silica have moderate strength and exhibit good dispersibility in the water-repellent film 300, and are therefore preferred in this respect.

[0080] The inorganic particles 7 are generally hydrophilic, and therefore preferably have been subjected to a hydrophobic treatment on the surface. Examples of methods for hydrophobic treatment include reacting a silanizing agent such as hexamethyldisilazane, a silane coupling agent, and the like with the inorganic particles 7. By hydrophobizing the surface of the inorganic particles 7, even if the surface is worn due to friction, the hydrophobicity is difficult to further decrease.

[0081] Here, as far as the water-repellent film 300 is concerned, even a composition that does not contain porous particles can be formed. However, in this case, the strength of the film tends to decrease and the wear resistance tends to decrease. In particular, due to the presence of oil 10, the strength and wear resistance of the film decrease significantly. In this embodiment 3, by adding porous particles, it is achieved to improve the strength of the film, and in particular, even if the film contains oil 10, it is achieved to obtain high film strength. In addition, the porous particles 16 have the effect of improving the strength of the film when the oil 10 is added and the effect of promoting water repellency when the water-repellent film 300 is damaged and a hydrophilic surface is produced. This is for the same reason as in embodiment 1.

[0082] The porous particles have the effect of increasing the strength of the water-repellent film 300. On the other hand, they are easily broken during wear, and do not affect the wear suppression effect produced by the spherical particles 5 and the characteristics of ensuring the flatness of the wear surface. On the broken surface of the porous particles, there is impregnated oil 10, so that high water repellency is maintained. If the average particle size of the porous particles is less than 1 μm, the wear surface is sometimes easily hydrophilized. On the other hand, if the average particle size of the porous particles exceeds 5 μm, a large hydrophilic surface is generated during crushing, and water adhesion is sometimes easy to occur. It should be noted that the average particle size of the inorganic particles 7 is a value measured by a laser diffraction particle size distribution measuring device.

[0083] (Inorganic Nanoparticles 11)

[0084] The inorganic nanoparticles 11 are silicon dioxide, aluminum oxide, zirconium oxide or titanium dioxide. The surface of the inorganic nanoparticles 11 is generally hydrophilic, so it is preferred to use a product that has been subjected to a hydrophobic treatment on the surface. As for the method of hydrophobic treatment, there can be cited a method of reacting a silanizing agent such as hexamethyldisilazane, a silane coupling agent, etc. with the inorganic nanoparticles 11. In this case, since highly stable hydrophobicity is obtained, it is preferred. In addition, as for the method of hydrophobic treatment, there can also be cited a method of mixing an organic silicon compound or a fluorocarbon compound having a low molecular weight compared to the water-repellent resin 15 with the inorganic nanoparticles 11 and adsorbing it on the surface. It is also preferred to use a method of reducing the hydrophilicity by heat treatment instead of the hydrophobic treatment of the inorganic nanoparticles 11. By heating the inorganic nanoparticles 11 to above 150°C, preferably above 300°C, the hydrophilicity is reduced, and the water repellency of the water-repellent film 300 is easily manifested.

[0085] The average particle size of the primary particles of the inorganic nanoparticles 11 is more than 2nm and less than 20nm, preferably more than 5nm and less than 15nm. If the average particle size of the primary particle size of the inorganic nanoparticles 11 is less than 2nm, the preparation of the coating composition for topcoat formation becomes difficult, and the water repellency of the water-repellent film 300 becomes insufficient. On the other hand, if the average particle size of the primary particles of the inorganic nanoparticles 11 exceeds 20nm, the water repellency of the water-repellent film 300 becomes insufficient, and if repeatedly rubbed, the water repellency is easily lost. It should be noted that the average particle size of the inorganic nanoparticles 11 is a value measured by a laser diffraction particle size distribution measuring device.

[0086] (Oil 10)

[0087] The oil 10 is, for example, silicone oil or fluoro oil. Examples of silicone oil include dimethyl silicone oil, amino-modified silicone oil, alkyl-modified silicone oil, epoxy-modified silicone oil, and higher fatty acid-modified silicone oil. Examples of fluoro oil include perfluoropolyether (PFPE) and polychlorotrifluoroethylene (PCTFE).

[0088] (Water-repellent resin 15)

[0089] When fluororesin is used as the water-repellent resin 15 and silicone oil is used as the oil 10 , the fluororesin and silicone oil are not compatible. Therefore, the silicone oil tends to be localized around the spherical particles 5 or the inorganic nanoparticles 11 , and the generation of voids 9 tends to be suppressed.

[0090] The mass ratio of the spherical particles 5 to the water-repellent resin 15 in the water-repellent film 300 is preferably 10% to 500% by mass, more preferably 30% to 200% by mass. If the spherical particles 5 are less than 10% by mass, the water-repellent film 300 may not have sufficient unevenness, and thus may not have sufficient water repellency. If the spherical particles 5 are more than 500% by mass, the water-repellent film 300 may not have sufficient strength.

[0091] The mass ratio of the inorganic nanoparticles 11 to the water-repellent resin 15 in the water-repellent film 300 is preferably 5% by mass or more and 200% by mass or less, and more preferably 10% by mass or more and 100% by mass or less. If the mass ratio is less than 5%, sufficient water repellency may not be achieved when the water-repellent film 300 is abraded. If the mass ratio exceeds 200% by mass, sufficient strength may not be achieved as the water-repellent film 300.

[0092] The mass ratio of the porous particles as the inorganic fine particles 7 to the water-repellent resin 15 in the water-repellent film 300 is preferably 5% by mass or more and 200% by mass or less, and more preferably 10% by mass or more and 100% by mass or less. If the mass ratio is less than 5%, sufficient water repellency may not be obtained when the water-repellent film 300 is worn. If the mass ratio exceeds 200% by mass, sufficient strength may not be obtained as the water-repellent film 300.

[0093] The mass ratio of the oil 10 to the total mass of the water-repellent resin 15, the inorganic fine particles 7, and the inorganic nanoparticles 11 in the water-repellent film 300 is preferably 1% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 20% by mass or less. If the mass ratio of the oil 10 is too low, the gaps 9 formed between the water-repellent resin 15 and the spherical particles 5, between the water-repellent resin 15 and the inorganic nanoparticles 11, or between the water-repellent resin 15 and the porous particles may not be filled. On the other hand, if the mass ratio of the oil 10 is too high, excess oil 10 may precipitate on the surface of the water-repellent film 300, causing dirt to form and reducing water repellency.

[0094] As for the water-repellent film 300, a water-repellent film-forming coating composition containing spherical particles 5, inorganic nanoparticles 11, porous particles, water-repellent resin 15, oil 10, and a solvent (intermediary) capable of dissolving the water-repellent resin 15 and being compatible with the oil 10 is applied to the substrate 1 and formed. As for the total amount of the spherical particles 5, inorganic nanoparticles 11, porous particles, water-repellent resin 15, and oil 10, it is preferably 3% by mass or more and 70% by mass or less relative to the water-repellent film-forming coating composition. If the total amount of the spherical particles 5, inorganic nanoparticles 11, porous particles, water-repellent resin 15, and oil 10 is less than 3% by mass, the spherical particles 5 become easy to settle, and the handling property of the coating composition is reduced. And then, sometimes the spherical particles 5 cannot be stably fixed in the water-repellent film 300. On the other hand, if the total amount of the spherical particles 5 , the inorganic nanoparticles 11 , the porous particles, the water-repellent resin 15 , and the oil 10 exceeds 70% by mass, it may be difficult to uniformly form the water-repellent film 300 .

[0095] A crosslinking agent may be added to the water-repellent film-forming coating composition to improve the strength of the water-repellent film 14. Furthermore, general additives may be added to the water-repellent film-forming coating composition to improve coating properties or water repellency. For the preparation of the water-repellent film-forming coating composition, a liquid dispersing device such as a homogenizer, dissolver, or high-pressure dispersing device is preferably used to prevent the inorganic nanoparticles 11 from remaining as large aggregates.

[0096] The water-repellent film is formed by applying a coating composition by spraying, brush coating or roller coating. With regard to the thickness of the water-repellent film 300, as average thickness, it is preferably more than 1 / 3 times and less than 5 times the average particle size of the spherical particles 5. If the thickness of the water-repellent film 300 is less than 1 / 3 times the average particle size of the spherical particles 5, sufficient wear resistance can not be obtained sometimes. On the other hand, if the thickness of the primer layer 2 exceeds 5 times the average particle size of the spherical particles 5, the intensity of the water-repellent film 300 is reduced sometimes, or the outward appearance of the water-repellent film 300 is deteriorated.

[0097] By forming such a water-repellent film 300 on the substrate 1, a film that easily maintains water repellency can be obtained. In this third embodiment, the water-repellent film comprises oil 10. The film is impregnated with oil 10, maintaining high water repellency and suppressing the adhesion of water droplets. Therefore, degradation due to friction is less likely to occur, and even if localized reduction in super-water repellency occurs, initial performance is maintained.

[0098] In the water-repellent film 300 that present embodiment 3 relates to, if by the surface friction of water-repellent film 300, the film formed on the spherical particles 5 of water-repellent film 300 is worn away, but the film formed on the recessed portion of water-repellent film 300 is not easy to wear away.If repeated friction, wear and tear is carried out, then spherical particles 5 become the state of being partially exposed, but become difficult to carry out further wear and tear.Although there is the tendency that tiny water droplets are easily attached near the spherical particles 5 exposed, water repellency is maintained.This is because the smoothness of the surface of spherical particles 5 is high, dense and hardness is high, so due to excellent wear resistance.In water-repellent film 300, with regard to the film formed in the part beyond spherical particles 5, contain inorganic microparticles 7 and inorganic nanoparticles 11 and water-repellent resin 15 and oil 10 as porous particles, it has water repellency separately.Therefore, even when wear and tear is carried out, the exposed part also has water repellency, can suppress the water repellency reduction of water-repellent film 300.

[0099] Example

[0100] Hereinafter, although an Example and a comparative example are shown and embodiment is demonstrated concretely, embodiment is not limited to the following Example.

[0101] [Example 1-2, Comparative Example 1-2]

[0102] A mixture of 20% by mass of a hydrophobized product (average particle size 3.5 μm) obtained by mixing spherical fused silica particles (manufactured by Denka Co., Ltd.) with hexamethyldisilazane and drying the mixture as spherical particles 5, 5% by mass of Nipgel AY-200 silica gel particles (average particle size 2.1 μm, manufactured by Tosoh Silica Co., Ltd.) as inorganic fine particles 7, 10% by mass of a cross-linked fluororesin (Bonfluon GT-SR, manufactured by AGC Co-Tech Co., Ltd.) as base resin 6, and mineral spirits as a solvent was prepared. To this mixture, dimethyl silicone (KF-96-3000cs, manufactured by Shin-Etsu Silicone Co., Ltd.) was added as oil 10 to prepare a primer coating. The amount of oil added in Table 1 represents the value relative to the total amount of the inorganic fine particles 7 and base resin 6.

[0103] As the inorganic nanoparticles 11, silica nanoparticles (AEROSIL R 976, manufactured by Japan Aerosil Co., Ltd., with an average particle size of 12 nm in solvent) treated with dimethyldichlorosilane were used. As the water-repellent resin 15, a silicone resin (KR221, manufactured by Shin-Etsu Silicone Co., Ltd.) was used, and xylene was used as the solvent to prepare a topcoat liquid. This topcoat liquid was sprayed onto a glass plate and dried to obtain a highly water-repellent film with a water contact angle of 145°. This film peeled off after only a few rubbings with a nonwoven fabric, indicating a lack of abrasion resistance.

[0104] The mortar board surface was sprayed with a primer. After 24 hours from the primer application, the topcoat was sprayed. The resulting coating film was vigorously rubbed with a 5mm diameter stainless steel rod to expose the base. Water was sprayed immediately after exposure and one day later, and the adhesion of water droplets was observed. Furthermore, electrode terminals were crimped onto the resulting coating film at a distance of 10mm, and a high voltage discharge was applied to degrade the film surface. Water was sprayed immediately after exposure and one day later, and the adhesion of water droplets was observed.

[0105] [Table 1]

[0106]

[0107] In Examples 1 and 2, the obtained films showed high water repellency with a water contact angle of more than 140°. The water repellency of the damaged part caused by rubbing is reduced, and water is attached by spraying water. In Example 1, linear water is attached in a manner that covers the entire damaged part, but in Example 2, water is attached not to the entire damaged part but as fine water droplets. This is because the reduction in water repellency is reduced due to the large amount of oil added. After rubbing for 1 day, it can be seen that the attachment of water in Example 1 is also reduced, and the water repellency is restored. Immediately after discharge, water is attached in the form of lines throughout the discharge concave holes in both Examples 1 and 2, but after 1 day, the attachment of water droplets in Example 1 and the attachment of water in Example 2 disappear, and the water repellency is restored.

[0108] Comparative Example 1 shows a film without Oil 10 added. While a high contact angle was achieved, water repellency decreased due to rubbing and discharge, and did not recover even after standing. This result demonstrates that the addition of oil suppresses and restores water repellency. Comparative Example 2 shows an example in which an excessive amount of Oil 10 was added. The contact angle was low, and even water droplets adhered to unscratched areas after water spraying. This demonstrates the necessity of an appropriate amount of Oil 10.

[0109] [Examples 3-4, Comparative Examples 3-9]

[0110] As spherical particles 5, spherical fused silica particles (manufactured by Denka Co., Ltd.) hydrophobized with hexamethyldisilazane were prepared, each having a different average particle size. As inorganic fine particles 7, inorganic fine particles having different average particle sizes were selected (Silhostar KE-P50; 0.5 μm, manufactured by Nippon Shokubai Co., Ltd., Nipgel AZ-204; 1.3 μm, AY-200; 2.1 μm, and AY-601; 6.0 μm, manufactured by Tosoh Silica Co., Ltd.). The primer coating material shown in Table 2 was prepared by mixing 10% by mass of a cross-linked fluororesin (Bonfluon GT-SR, manufactured by AGC Co-Tech Co., Ltd.) as a base resin 6 and 2% by mass of a dimethyl silicone (KF-96-3000cs, manufactured by Shin-Etsu Silicone Co., Ltd.) as an oil 10 (based on the total of the base resin 6 and the inorganic fine particles 7).

[0111] On the surface of the mortar board, the primer was sprayed, and after 24 hours, the top coating liquid of Example 1 was sprayed. After coating, the coating film was wiped with a non-woven fabric at 80 g / cm 2 The coating was pressed with a load of 100° and rubbed back and forth 10 times. The water contact angle was measured before and after rubbing. The rubbed coating was vigorously rubbed with a 5 mm diameter stainless steel rod to expose the base. Water was then sprayed immediately after exposure and one day later, and the adhesion of water droplets was observed. Table 2 shows the results of confirming the degradation of the coating film due to friction using water contact angles, as well as the water repellency of the rubbed coating film after scratching.

[0112] [Table 2]

[0113]

[0114] In Examples 3 and 4, the water contact angle exceeded 140° even after friction, demonstrating high abrasion resistance. The scratched area became hydrophilic immediately after scratching, and the water spray adhered in a linear pattern, covering the entire scratch. After one day, the water repellency was restored, with only small water droplets adhering.

[0115] Comparative Examples 3-5 demonstrate the effects of spherical particles 5. Comparative Example 3 shows an example with too small a particle size, Comparative Example 4 shows an example with too large a particle size, and Comparative Example 5 shows an example with too little added. In all cases, friction significantly reduces the contact angle, and water droplets adhere to the entire surface. This demonstrates that without using appropriate spherical particles 5, a water-repellent film with abrasion resistance cannot be obtained.

[0116] Comparative Examples 6-9 demonstrate the effects of Inorganic Particle 7. Comparative Example 6 shows a small addition amount, Comparative Example 7 shows an excessive addition amount, Comparative Example 8 shows an excessively large particle size, and Comparative Example 9 shows an excessively small particle size. When the addition amount is small, hydrophilicity decreases due to friction. It can be seen that high water repellency cannot be achieved when the addition amount is excessive or the particle size is inappropriate.

[0117] [Example 5, Comparative Example 10]

[0118] As the base resin 6, urethane dispersion (UW-5002E, manufactured by UBE Co., Ltd.), fluororesin dispersion (AD911E, manufactured by AGC Co., Ltd.), and acrylic emulsion (A-104, manufactured by Toagosei Co., Ltd.) were used; as the spherical particles 5, spherical silica (average particle size 3.6 μm, manufactured by Denka Co., Ltd.) and spherical alumina (average particle size 4.3 μm, manufactured by Denka Co., Ltd.) were used; as the inorganic fine particles 7, silica gel particles (Nipgel) were used. As oil 10, silicone oil (KF-352A, Shin-Etsu Silicone Co., Ltd.) and fluoro oil (Demunam S-65, Daikin Industries, Ltd.) were mixed in water at the ratios shown in Table 3 and treated with a disperser to prepare a primer coating. The information in the column for oil 10 represents the mass ratio relative to the total of base resin 6 and inorganic fine particles 7.

[0119] The primer was sprayed onto the galvanized steel sheet and dried at 130° C. for 15 minutes. The topcoat of Example 1 was then sprayed. The same friction and scratch tests as in Example 3 were then performed.

[0120] [Table 3]

[0121]

[0122] Examples 5 to 10 use a urethane resin or fluororesin as the base resin 6, silica or alumina as the spherical particles 5, and silicone oil or fluorooil as the oil 10, resulting in a water-based primer. These coatings achieve high water repellency, abrasion resistance, and water repellency retention even after scratching. Comparative Example 10 uses an acrylic resin as the base resin 6, resulting in easy degradation due to friction.

[0123] [Example 11, Comparative Examples 11-12]

[0124] A fluororesin (Bonfluon GT-SR, manufactured by AGC Co-tech Co., Ltd.) was used as the base resin 6, spherical silica (average particle diameters of 3.5 μm and 12 μm, manufactured by Denka Co., Ltd.) was used as the spherical particles 5, fluororesin fine particles (Dionyx PTFE Microper TF9207Z, 4 μm, manufactured by Sly-Em Japan Co., Ltd.) were used as the inorganic fine particles 7, and a fluorinated oil (Demunam S-65, manufactured by Daikin Industries, Ltd.) was used as the oil 10. A primer coating containing a mineral spirit solvent was prepared using the mixing ratios shown in Table 4. The expression for the oil 10 represents the mass ratio relative to the total of the base resin 6 and the inorganic fine particles 7.

[0125] As inorganic nanoparticles 11, silica nanoparticles (AEROSIL R 976, manufactured by Japan Aerosil Co., Ltd., with an average particle size of 12 nm) treated with dimethyldichlorosilane hydrophobization were used. As water-repellent resin 15, fluororesin (FS-1610, manufactured by Fluorotech Co., Ltd.) was used, and a fluorine-based solvent (AE-3000, manufactured by AGC Co., Ltd.) was used as a solvent to prepare a topcoat. By spraying and drying the topcoat on a glass plate, a highly water-repellent film having a water contact angle of 155 ° was obtained. The film was peeled off after only a few rubbings with a non-woven fabric and had no wear resistance. Since it was a coating liquid of a fluorine-based solvent, even if the base coating film was composed of a non-cured resin, the coating that did not deteriorate the base coating film was also possible. The primer was sprayed on a galvanized steel sheet, and after 1 day, the topcoat was sprayed. Then, similarly to Example 3, friction and scratch tests were performed.

[0126] [Table 4]

[0127]

[0128] Example 11, using fluororesin particles as the inorganic fine particles 7, achieved high water repellency, abrasion resistance, and water repellency retention after scratching. Comparative Example 11, in which the fluororesin particles were excessively large, and Comparative Example 12, in which the fluororesin particles were too large compared to the spherical particles 5, failed to achieve abrasion resistance in either case, demonstrating the need for an appropriate particle size and amount of fluororesin particles.

[0129] [Example 12, Comparative Examples 13-15]

[0130] A fluororesin (Bonfluon GT-SR, manufactured by AGC Co., Ltd.) was used, as the spherical particles 5, spherical silica (average particle size 3.5 μm, manufactured by Denka Co., Ltd.) treated to make it hydrophobic with hexamethyldisilazane was used, as the inorganic nanoparticles 11, silica nanoparticles (X-30, average primary particle size 7 nm, manufactured by Tokuyama Co., Ltd.) treated to make it hydrophobic with dimethyldichlorosilane were used, as the inorganic nanoparticles 7, water-repellent silica particles (AZ-260, 2 μm, manufactured by Tosoh Silicone Co., Ltd.) were used, and as the oil 10, silicone oil (KF-96-3000cs, manufactured by Shin-Etsu Silicone Co., Ltd.) was used to prepare a coating solution of a mineral spirit solvent at the mixing ratio shown in Table 5. The expression in the column "Oil 10" indicates the mass ratio relative to the total of the fluororesin, the inorganic fine particles 7, and the inorganic nanoparticles 11. This liquid was sprayed onto a galvanized steel sheet and dried. The friction and scratch tests were then conducted in the same manner as in Example 3.

[0131] [Table 5]

[0132]

[0133] Example 12, a film coated once, achieved high water repellency, abrasion resistance, and water repellency retention after scratching. Comparative Example 13, a composition lacking inorganic microparticles 7, failed to achieve abrasion resistance. Comparative Example 14, a composition lacking inorganic nanoparticles 11, failed to achieve high water repellency. Comparative Example 15, a composition lacking oil 10, showed reduced water repellency in damaged areas, which did not recover over time. This demonstrates that by properly blending the various components, water repellency, abrasion resistance, and water repellency retention after scratching can be achieved.

[0134] Description of Reference Signs

[0135] 1. Substrate, 2. Primer, 3. Topcoat, 5. Spherical particles, 6. Base resin, 7. Inorganic fine particles, 9. Voids, 10. Oil, 11. Inorganic nanoparticles, 12. Water-repellent resin, 15. Water-repellent resin, 100. Water-repellent film, 100a. Water-repellent film, 200. Water-repellent film, 207. Inorganic fine particles, 300. Water-repellent film.

Claims

1. A water-repellent film comprising: Spherical particles, Inorganic fine particles having an average particle size smaller than the average particle size of the spherical particles, Inorganic nanoparticles with fine concavo-convex surfaces, Water-repellent resin, and Oil.

2. The water-repellent film according to claim 1, comprising: a primer layer comprising the spherical particles, the inorganic fine particles, the oil, the spherical particles, and a base resin; and The present invention comprises the inorganic nanoparticles and the water-repellent resin, and a top coat layer formed on the primer layer.

3. The water-repellent film according to claim 2, wherein The oil accounts for 1% to 30% by weight of the total of the base resin and the inorganic fine particles.

4. The water-repellent film according to claim 2 or 3, wherein The base resin is polyurethane resin or fluororesin.

5. The water-repellent film according to any one of claims 2 to 4, wherein The water contact angle of the top coating layer is 140° or greater.

6. The water-repellent film according to any one of claims 1 to 5, wherein The spherical particles have an average particle diameter of 2 μm or more and 50 μm or less, and are at least one selected from the group consisting of spherical fused silica particles, spherical fused alumina particles, and spherical silicone resin particles.

7. The water-repellent film according to any one of claims 1 to 6, wherein The inorganic fine particles are porous particles having an average particle size of 1 μm or more and 5 μm or less.

8. The water-repellent film according to any one of claims 1 to 7, wherein The inorganic fine particles are fluororesin particles having an average particle size of 0.05 μm or more and 15 μm or less.

9. The water-repellent film according to any one of claims 1 to 8, wherein The inorganic nanoparticles have an average particle diameter of 2 nm to 20 nm.

10. The water-repellent film according to any one of claims 1 to 9, wherein The water-repellent resin is a fluororesin or a silicone resin.

11. The water-repellent film according to any one of claims 1 to 10, wherein The amount of the oil added is 1% by weight or more and 30% by weight or less based on the total amount of the water-repellent resin, the inorganic nanoparticles, and the spherical particles.

12. The water-repellent film according to any one of claims 1 to 11, wherein The oil is impregnated in the spherical particles.

13. An article comprising: Base material, and The water-repellent coating according to any one of claims 1 to 12 formed on the substrate.

14. The article according to claim 13 as appended to any one of claims 2 to 5, comprising a solvent for dissolving the base resin. 15 . The article according to claim 13 , comprising a solvent that dissolves the water-repellent resin.

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