Water-repellent sheet, water-repellent coating material and water-repellent molded article

Abstract

To provide a water-repellent sheet, a water-repellent coating material and a water-repellent molded article which can improve film strength, adhesion and abrasion resistance (re-workability).SOLUTION: A water-repellent sheet includes inside and outside, includes an inside layer 11 positioned inside, and an outside layer 12 which is stacked on the inside layer 11 and is positioned outside, wherein the outside layer 12 contains uneven shape imparting particles, and the inside layer 11 is a rubber layer, a resin layer, a fabric layer or a metal layer. The water-repellent sheet can improve film strength, adhesion and abrasion resistance (re-workability) of the water-repellent sheet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a water-repellent sheet, a water-repellent paint, and a water-repellent molded article.

Background Art

[0002] For example, a technique related to a protective material for protecting the human body from toxic gases, liquids, etc. is disclosed in Japanese Patent No. 5784812 (Patent Document 1). For such a protective material, good water repellency on the surface of the material is required against toxic liquids, etc., and techniques related to the surface treatment of the material are disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-2903 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2010-24279 (Patent Document 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When harmful liquids, etc. adhere to a water-repellent sheet or a member with a water-repellent paint applied thereto, a decontamination operation using a decontaminant such as an aqueous bleach solution is required. This operation is performed by a plurality of decontamination workers, but the problem is that the human labor and working time required for the decontamination operation are large. Furthermore, improvement in the film strength, adhesion, and abrasion resistance (reprocessability) of the water-repellent sheet and the member with the water-repellent paint applied thereto has also been demanded.

[0005] In the present disclosure, it is an object to solve the above problems and provide a water-repellent sheet, a water-repellent paint, and a water-repellent molded article capable of improving film strength, adhesion, and abrasion resistance (reprocessability).

Means for Solving the Problems

[0006] [1]: A water-repellent sheet having an inner side and an outer side, comprising an inner layer located on the inner side and an outer layer laminated on the inner layer and located on the outer side, wherein the outer layer contains concavo-convex shape-imparting particles, and the inner layer is a rubber layer, a resin layer, a fabric layer, or a metal layer.

[0007] [2]: The shape of the concavo-convex shape-imparting particles is tetrapod-like, needle-like, polygonal, or spherical. The water-repellent sheet according to [1].

[0008] [3]: The concavo-convex shape-imparting particles are tetrapod-type zinc oxide. The water-repellent sheet according to [1] or [2].

[0009] [4]: The solid content ratio of the concavo-convex shape-imparting particles to the total solid content of the outer layer is 40 wt% to 60 wt%. The water-repellent sheet according to any one of [1] to [3].

[0010] [5]: The outer layer further contains an infrared reflective material. The water-repellent sheet according to any one of [1] to [4].

[0011] [6]: The infrared reflective material is a pigment containing at least one metal element such as titanium, manganese, calcium, iron, bismuth, chromium, nickel, and the infrared reflective material is contained in an amount of 5 wt% to 30 wt% with respect to the solid content of the outer layer excluding the infrared reflective material. The water-repellent sheet according to [5].

[0012] [7]: The average particle diameter of the infrared reflective material is 600 nm or more and 1500 nm or less. The water-repellent sheet according to [5] or [6].

[0013] [8]: On the surface of the inner layer opposite to the surface where the outer layer is laminated, a fabric and a second inner layer are laminated in the described order, and the second inner layer is a rubber layer, a resin layer, a fabric layer, or a metal layer. The water-repellent sheet according to any one of [1] to [7].

[0014] [9]: The fabric is a woven fabric, a knitted fabric, or a non-woven fabric. The water-repellent sheet according to [8].

[0015]

[10] : Different types of materials are used for the inner layer and the second inner layer. The water-repellent sheet according to [8] or [9].

[0016]

[11] : The water-repellent sheet according to any one of [1] to

[10] is used in a water distribution pipe, a water storage tank, a bridge, a ship bottom, a roof, a tent, a tarp, an umbrella, an automobile body, building materials, clothing, sports and outdoor supplies, water-related supplies (washing face, bath, toilet, etc.), medical instruments (catheter wire, etc.), medical tools (apron, waterproof case, etc.), or ostomy-related products.

[0017]

[12] : A water-repellent paint or a water-repellent molded product including a base material and concavo-convex shape-imparting particles contained in the base material.

[0018]

[13] : The shape of the concavo-convex shape-imparting particles is a tetrapod shape, a needle shape, a polygonal shape, or a spherical shape. The water-repellent paint or the water-repellent molded product according to

[12] .

[0019]

[14] : The concavo-convex shape-imparting particles are tetrapod-type zinc oxide. The water-repellent paint or the water-repellent molded product according to

[11] or

[12] .

[0020]

[15] : The ratio of the concavo-convex shape-imparting particles to the base material is 40 wt% to 60 wt%. The water-repellent paint or the water-repellent molded product according to any one of

[11] to

[13] .

[0021]

[16] : The base material further includes an infrared reflective material. The water-repellent paint or the water-repellent molded product according to any one of

[11] to

[14] .

[0022]

[17] : The infrared reflective material is a pigment containing at least one kind of metallic element such as titanium, manganese, calcium, iron, bismuth, chromium, or nickel, and the infrared reflective material is contained in an amount of 5 wt% to 30 wt% based on the solid content excluding the infrared reflective material among the resin materials, which is the water-repellent paint or water-repellent molded article described in

[15] .

[0023]

[18] : The average particle diameter of the infrared reflective material is 600 nm or more and 1500 nm or less, which is the water-repellent paint or water-repellent molded article described in

[15] or

[16] .

[0024]

[19] : The water-repellent paint or water-repellent molded article according to any one of

[12] to

[18] is used for water pipes, water storage tanks, bridges, ship bottoms, awnings, tents, tarps, umbrellas, automobile bodies, building materials, clothing, sports and outdoor goods, water-related goods (washing, bath, toilet, etc.), medical instruments (catheter wires, etc.), medical supplies (aprons, waterproof cases, etc.), or ostomate-related products.

Effect of the Invention

[0025] According to the present disclosure, it is possible to provide a water-repellent sheet, a water-repellent paint, and a water-repellent molded article capable of improving film strength, adhesion, and abrasion resistance (reprocessability).

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

MODE FOR CARRYING OUT THE INVENTION

[0027] Regarding the water - repellent sheet, water - repellent paint, and water - repellent molded product of each embodiment based on the present disclosure, they will be described below with reference to the drawings. In the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present invention is not necessarily limited to that number, amount, etc. For the same parts and corresponding parts, the same reference numerals are given, and duplicate explanations may not be repeated. It is initially planned to use the configurations in the embodiments in appropriate combinations. For ease of understanding, the film thickness and layer thickness shown in the figures are described as different from the actual ratios.

[0028] In the specification, "outer side" means the side exposed to liquids, etc. when the water - repellent sheet is in use, and "inner side" means the side not exposed to liquids, etc. when the water - repellent sheet is in use.

[0029] [Embodiment 1: Water - repellent sheet 1] Next, with reference to FIGS. 1 to 3, the water - repellent sheet 1 of this embodiment will be described. FIG. 1 is a cross - sectional structure diagram of the water - repellent sheet 1, FIG. 2 is an enlarged view showing the shape of the tetrapod - type zinc oxide, and FIG. 3 is an electron micrograph of the laminated structure of the tetrapod - type zinc oxide.

[0030] This water-repellent sheet 1 is a water-repellent sheet having an inner side and an outer side, and includes an inner layer 11 located on the inner side and an outer layer 12 laminated on the inner layer 11 and located on the outer side. The inner layer 11 is a rubber layer, a resin layer, a fabric layer, or a metal layer. The thickness of the inner layer 11 is about 20 μm to several millimeters, specifically about 0.1 mm to 0.3 mm. When the inner layer 11 is a rubber layer, the types of rubber used include nitrile rubber (NBR), epichlorohydrin rubber (CO, ECO), chlorinated butyl rubber (CIIR), butyl rubber (IIR), brominated butyl rubber (BrIIR), fluororubber, chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), urethane rubber, etc. The inner layer 11 is not limited to rubber, and films, fabrics (woven fabrics, knitted fabrics, non-woven fabrics), metals, etc. may also be used.

[0031] For the outer layer 12, a rubber layer or a resin layer is used, and it is preferably made of the same material as the inner layer 11. Preferably, the same material as the inner layer 11 contains particles for imparting an uneven shape. Instead of the inner layer 11, resins (such as Vylon (registered trademark), Hardlen (registered trademark), urethane, PVC, etc.) may also be used. In this specification, the particles for imparting an uneven shape refer to materials that can impart an uneven shape to the surface of the outer layer 12. The thickness of the outer layer 12 is about 10 μm to 100 μm.

[0032] Examples of the shape of the particles for imparting an uneven shape include tetrapod shape, needle shape, spherical shape, polygonal shape, etc. Examples of the raw materials include inorganic oxides such as alumina, potassium titanate, wollastonite, zinc oxide, aluminum borate; metals such as chromium, copper, iron, nickel; and inorganic substances other than inorganic oxides and metals such as silicon carbide, graphite, and silicon nitride. Specific examples include tetrapod-type zinc oxide, spherical silica, etc.

[0033] As shown in Fig. 2, the crystal R of tetrapod-shaped zinc oxide has the shape of a "tetrapod (registered trademark)" type for revetments. Specifically, the crystal R is a needle-shaped crystal formed by the reaction of zinc metal vapor and oxygen, growing in the C-axis direction of hexagonal ZnO from every other 4 sides of each regular octagon. The length of one needle-shaped crystal is 1 to 50 μm, preferably 5 to 30 μm, and more preferably 8 to 20 μm. As shown in Fig. 3, in the laminated structure of tetrapod-shaped zinc oxide, a plurality of crystals R overlap and are laminated, so that the outer layer 12 becomes a porous layer structure material with unevenness on the surface.

[0034] The outer layer 12 has a structure in which the same kind of rubber or resin as the inner layer 11 is dispersed with tetrapod-shaped zinc oxide. Tetrapod-shaped zinc oxide is blended at 30 wt% to 70 wt% (preferably 40 wt% to 60 wt%) based on the total solid content (rubber or resin + tetrapod-shaped zinc oxide) of the outer layer 12. Then, when the outer layer 12 is a rubber layer, it becomes brittle, but when the inner layer is the same kind of rubber layer, a crosslinked structure is formed between the inner layer 11 and the outer layer 12, which are the same kind of rubber layers, by heat vulcanization, and they are firmly bonded, improving the film strength of the outer layer 12. For example, tetrapod-shaped single crystal powder made of zinc oxide ("Panatetra WZ-0501" manufactured by Amtech Co., Ltd., average fiber length (needle-shaped part): about 10 μm) can be used.

[0035] In the outer layer 12, the ratio of rubber or resin, ZnO, and solvent (toluene, ethyl acetate, etc.) is preferably 5:5:90 to 25:25:50.

[0036] Examples of the coating method of the outer layer 12 on the inner layer 11 include kiss coating (gravure coating), knife coating, etc.

[0037] As a result, the unevenness appearing on the front side of this outer layer 12 brings good results for the evaluation results of the water repellency of the water repellent sheet 1 described later.

[0038] [Evaluation Results of Water Repellent Sheet 1] Next, with reference to FIGS. 4 to 6, the evaluation results of the water-repellent sheet 1 will be described. FIG. 4 is a schematic diagram showing the contact angle, FIG. 5 is a schematic diagram showing the sliding angle, and FIG. 6 is a diagram showing the evaluation results of the water-repellent sheet 1 and the comparative examples.

[0039] First, with reference to FIGS. 4 and 5, the "θ: contact angle (static)" and "α: sliding angle (dynamic)" used for evaluating the droplets attached to the material surface will be described. Referring to FIG. 4, the evaluation of the "θ: contact angle (static)" evaluates the adhesion state of the droplet W1 to a horizontal surface. As shown in FIG. 4, the larger the angle θ formed between the tangent to the surface of the droplet W1 and the horizontal plane, the smaller the amount of adhesion of the droplet W1 to the horizontal surface, and the droplet W1 maintains a shape close to a sphere and can be evaluated as a droplet W1 with good water repellency. If θ is 150 degrees or more, the droplet W1 bounces on the horizontal surface and can be said to be in a state where it is easy to slide.

[0040] On the other hand, referring to FIG. 5, the evaluation of the "α: sliding angle (dynamic)" evaluates the inclination angle at which the droplet W1 starts to fall. As shown in FIG. 5, the smaller the adhesion force of the droplet W1 to the inclined surface, the smaller the inclination angle α at which the droplet W1 starts to fall. Therefore, the smaller the inclination angle α at which the droplet W1 starts to fall, the better the water repellency of the droplet W1 can be evaluated.

[0041] Next, with reference to FIG. 6, the evaluation results of the water-repellent sheet 1 will be described. It is a diagram showing the evaluation results of the water-repellent sheets of each embodiment.

[0042] As an evaluation object, the water repellency (water) was evaluated as the "θ: contact angle (static)". Similarly, the water repellency (water) was evaluated as the "α: sliding angle (dynamic)". Specifically, for the measurement method of the contact angle and the sliding angle, the dropping amount was 30 μL, the measuring device was Kyowa Interface Science DMo710, and the sliding angle determination was when the advancing angle moved 1 mm.

[0043] In the case of the water-repellent sheet in the comparative example, the water repellency (water) in the "θ: contact angle (static)" was 99°, and the water repellency (water) in the "α: sliding angle (dynamic)" was 41°.

[0044] In the water-repellent sheet 1 of Embodiment 1, the water repellency (water) at "θ: contact angle (static)" was 130°, and the water repellency (water) at "α: sliding angle (dynamic)" was 8°.

[0045] In this way, in the evaluation of "θ: contact angle (static)" and "α: sliding angle (dynamic)", the water-repellent sheet 1 of Embodiment 1 was evaluated higher than the evaluation of the comparative example. Therefore, it can be seen that the water-repellent sheet 1 of Embodiment 1 has excellent water-repellent performance compared to the comparative example. As a result, even if a harmful liquid or the like comes into contact with the outside of the water-repellent sheet 1, it is difficult for the harmful liquid or the like to stop on the surface of the water-repellent sheet 1, and it is possible to suppress the adhesion of harmful liquids or the like to the surface of the water-repellent sheet 1.

[0046] Thereby, it becomes possible to reduce the labor required for the decontamination work of harmful liquids or the like adhering to the outside of the water-repellent sheet 1. In addition, since the water-repellent performance is excellent, the protective performance is improved.

[0047] [Each Example] With reference to FIG. 7, each example in which evaluations of "film strength", "adhesion", and "abrasion resistance" are further added will be described. FIG. 7 is a diagram showing the evaluation results of Examples 11 to 20 and Comparative Example 1. The configuration of the water-repellent sheet used in the evaluation of FIG. 7 is the same as that of the water-repellent sheet 1 described with reference to FIGS. 3 to 5.

[0048] (1) In the processing step, with reference to FIG. 7, as the coating, the solid content ratio of ZnO (tetrapod-shaped zinc oxide) and the presence or absence of a vulcanization step are listed. The solid content ratio of ZnO is the blending ratio of the mass of the solid content of ZnO to the mass of the total solid content (rubber, resin + tetrapod-shaped zinc oxide). In the vulcanization step, by heating and vulcanizing, a crosslinked structure is formed between the same type of inner layer 11 and outer layer 12, and they are firmly bonded, improving the film strength of the outer layer 12.

[0049] (2) In the performance evaluation, "liquid repellency performance (contact angle, sliding angle)", "film strength", "adhesion", and "abrasion resistance" were evaluated. For "liquid repellency performance (contact angle, sliding angle)", it is the same as the evaluation method described in FIGS. 4 and 5. As the evaluation of "liquid repellency performance (contact angle, sliding angle)", "Grade A: Excellent", "Grade B: Good", "Grade C: Passable", and "Grade F: Not adoptable" were set.

[0050] As the evaluation of "film strength", a 180-degree bending test was conducted on the water-repellent sheet. Specifically, the appearance when the water-repellent sheet was bent 180 degrees by hand was observed. As the evaluation of "film strength", "Grade A: No change in appearance", "Grade B: Small cracks occurred", and "Grade C: Large cracks occurred" were set.

[0051] As the evaluation of "adhesion", a test using the cross-cut method (conforming to JIS K5600-5-6) was conducted on the water-repellent sheet. Specifically, cuts of 25 squares (2 mm wide, 5×5) were made on the surface of the water-repellent sheet 1B, tape was adhered, and then the surface state after the tape was peeled off was observed. As the evaluation of "adhesion", "0" in the classification of the test results in Table 1 of JIS K5600 was set as Grade A, "1" as Grade B, and "2 or more" as Grade C.

[0052] As the evaluation of "abrasion resistance", a flat abrasion test (conforming to JIS L1096) was conducted. The pressing load on the water-repellent sheet was 100 g, and P1500 was used for the abrasive paper. For "15 abrasions", regarding the retention rate of the contact angle after abrasion with respect to the initial contact angle, "Grade A: 70% or more for water, 25% or more for decane, 40% or more for 3-methoxybutyl acetate" was set, and "Grade C: Other than Grade A".

[0053] In Examples 11 to 20 shown in FIG. 7, in the case of the formulation where the solid content ratio of ZnO is 40 wt% to 60 wt% shown in Examples 11 to 13, for the water-repellent sheet employing a heat vulcanization process, the overall evaluation was “Evaluation A” as it was “Evaluation A” in all evaluation items. In addition, in the case of the formulation where the solid content ratio of ZnO is 40 wt% to 60 wt% shown in Examples 17 to 19, for the water-repellent sheet not employing a heat vulcanization process, although “Evaluation A” was not obtained in some evaluation items, “Evaluation A” was obtained as the overall evaluation. In FIG. 7, the solid content ratio of ZnO is described as a percentage.

[0054] As described above, it has also become possible to improve the film strength, adhesion, and abrasion resistance (reprocessability) of the protective clothing.

[0055] [Embodiment 2: Another Water-Repellent Sheet 1] In the water-repellent sheet 1, the outer layer 12 may have a structure in which tetrapod-shaped zinc oxide and an infrared reflective material are dispersed in the same kind of rubber or resin as the inner layer 11. In the outer layer 12, the tetrapod-shaped zinc oxide is contained in an amount of 30 wt% to 70 wt%, preferably 40 to 60 wt%, based on the solid content excluding the infrared reflective material among the total solid content (here, rubber or resin + tetrapod-shaped zinc oxide). Then, although the outer layer 12 becomes brittle, a crosslinked structure is formed between the same kind of inner layer 11 and outer layer 12 by heat vulcanization, and they are firmly bonded to improve the film strength of the outer layer 12. As the tetrapod-shaped zinc oxide, for example, a tetrapod-shaped single crystal powder made of zinc oxide (“Panatetra WZ-0501” manufactured by Amtech Co., Ltd., average fiber length (needle-like part): about 10 μm) can be used. In addition, when an additive is contained in the rubber or resin, the additive also enters the solid content excluding the infrared reflective material.

[0056] As a result, the unevenness appearing on the front side of the outer layer 12 brings good results for the evaluation results of the water repellency of the water-repellent sheet 1 described later.

[0057] In addition, the outer layer 12 contains an infrared reflective material. In this specification, the infrared reflective material means a material capable of reflecting light in the near-infrared region (780 nm to 2500 nm) contained in natural light. As the infrared reflective material, a pigment containing one or more metal elements such as titanium, manganese, calcium, iron, bismuth, chromium, nickel, etc. can be used. For example, metal oxides (TiO2, Fe2O3, Mn3O4, MnO2, Cr2O3, CoO, CuO, CaO) etc. can be used. In this embodiment, the content of the infrared reflective material contained in the outer layer 12 is 5 wt% to 30 wt%, preferably about 10 to 20 wt% with respect to the solid content excluding the infrared reflective material in the total solid content of the outer layer 12 (here, rubber + tetrapod-shaped zinc oxide).

[0058] The infrared reflective material can increase the solar reflectance of the outer layer 12. As a result, it can be expected to suppress the temperature rise inside the water-repellent sheet 1. Details will be described later with reference to FIG. 9.

[0059] (Evaluation method of water-repellent sheet) Next, the evaluation method of the water-repellent sheet of Embodiment 2 will be described. FIG. 8 is a schematic diagram showing a heat insulation test and surface temperature measurement. Note that the explanations for "θ: contact angle (static)" and "α: sliding angle (dynamic)" used for evaluating the droplets adhering to the material surface are the same as those described with reference to FIGS. 4 and 5. The judgment criteria are that "θ: contact angle (static)" of 130° or more is "〇", and less than 130° is "×". Also, "α: sliding angle (dynamic)" of 40° or less is "〇", and exceeding 40° is "×".

[0060] As evaluation items related to solar radiation countermeasures, each item of "color", "heat insulation rate", "surface temperature", and "solar reflectance" was evaluated.

[0061] The heat shielding rate was calculated according to the heat shielding property test for fabrics (JISL1951). Using the test device 10 shown in FIG. 8, the environmental temperature was set to 20°C to 25°C, and a reflector lamp 110 (Iwasaki Electric PRS-500W) was used as the light source. The output of the reflector lamp 110 was 500W. The distance to the water-repellent sheet sample S (sample-light source) was 40cm.

[0062] The irradiation time of the heat rays from the reflector lamp 110 was 15 minutes. A blank region R1 where the heat receiver 130 was not covered by the water-repellent sheet sample S and a region R2 where the heat receiver 130 was covered by the water-repellent sheet sample S were prepared. The temperature change of the heat receiver 130 was measured at multiple points, and the average value of the temperature change at each point was calculated. The temperature change of the water-repellent sheet sample S was measured by a thermo camera 141, and the temperature change of the heat receiver 130 was measured by a thermo camera 142. As the evaluation criteria, a surface temperature of less than 60°C 15 minutes after light irradiation was marked as "○", and a surface temperature of 60°C or higher was marked as "×".

[0063] Assume that before heat radiation (irradiation time 0 minutes), the average temperature of the heat radiation receiver 130 in region R1 is 20 degrees, and the average temperature of the heat radiation receiver 130 in region R2 is 20 degrees, and after heat radiation (irradiation time 15 minutes), the average temperature of the heat radiation receiver 130 in region R1 changes to 60 degrees, and the temperature of the heat radiation receiver 130 in region R2 changes to 40 degrees. In this case, since the temperature change ΔT in region R1 is 40 degrees and the temperature change ΔT in region R2 is 20 degrees, the heat shielding rate (%) of the water-repellent sheet sample S is ((40-20) / 40)×100(%)=50%. As the evaluation criteria, a heat shielding rate of 50% or more is indicated as "good", and a rate of less than 50% is indicated as "bad".

[0064] The shielding rate of the water-repellent sheet was calculated based on the above formula for calculating the heat shielding rate (%). Note that the surface temperature in Figure 9 indicates the surface temperature of the water-repellent sheet.

[0065] Regarding the solar reflectance, the spectral reflectance in the range of 300 - 2500 nm was measured using a spectrophotometer (UV-VIS-NIR spectrophotometer SolidSpec-3700, manufactured by Shimadzu Corporation), and based on JIS K 5602:2008 (Solar Reflectance of Coating Films), it was judged in the near-ultraviolet and visible light regions (300 - 780 nm) and the near-infrared region (780 - 2500 nm). The judgment criteria were that if the solar reflectance in the near-infrared region was 40% or more, it was marked as "〇", and if it was less than 40%, it was marked as "×". The color of the surface of the water-repellent sheet is not particularly limited.

[0066] (Examples and Comparative Examples) Next, as examples of Embodiment 2, water-repellent sheets 1A to 1C were manufactured as follows and the above evaluations were performed. Also, water-repellent sheets of Comparative Examples 1 and 2 were manufactured and the above evaluations were performed. Fig. 9 shows the evaluation results of water-repellent sheets 1A to 1C and the water-repellent sheets of Comparative Examples 1 and 2.

[0067] For the water-repellent sheet 1A, butyl rubber was used for the inner layer 11, and a coating material was knife-coated on the outside, dried, and heat-vulcanized to form the outer layer 12. The above coating material was mixed so that the mass ratio of butyl rubber:ZnO:solvent (toluene) was 17.5:17.5:65, and further, as an infrared reflecting material, "SG-101" manufactured by Ishihara Sangyo Co., Ltd. composed of metal elements of titanium, manganese, and calcium was used at a ratio of 10 wt% based on the solid content (butyl rubber and ZnO) of the above mixture.

[0068] The water repellency (water) at "θ: contact angle (static)" was 140°, and the water repellency (water) at "α: sliding angle (dynamic)" was 8°, which was good. Also, the "heat insulation rate" was 50%, the "surface temperature" was 59°C, and the "solar reflectance" was 13.2% in the "near-ultraviolet and visible light region (300 nm - 780 nm)" and 49.1% in the "near-infrared region (780 nm - 2500 nm)", and good results were obtained.

[0069] The water-repellent sheet 1B was produced in the same manner as the water-repellent sheet 1A except that an infrared reflecting material (Ishihara Sangyo Co., Ltd., product number SG101) was mixed at 15 wt% based on the solid content (butyl rubber and ZnO) of the mixture.

[0070] The water repellency (for water) at "θ: static contact angle" was 142°, and the water repellency (for water) at "α: dynamic sliding angle" was 7°, which were good. Also, the "heat insulation rate" was 53%, the "surface temperature" was 58°C, and the "solar reflectance" was 12.9% in the "near ultraviolet and visible light region (300 nm to 780 nm)" and 50.9% in the "near infrared region (780 nm to 2500 nm)", and good results were obtained.

[0071] The water repellent sheet 1C was produced in the same manner as the water repellent sheet 1A, except that an infrared reflective material (manufactured by Ishihara Sangyo Co., Ltd., product number SG101) was mixed at 20 wt% with respect to the solid content of the mixture (butyl rubber and ZnO).

[0072] The water repellency (for water) at "θ: static contact angle" was 139°, and the water repellency (for water) at "α: dynamic sliding angle" was 9°, which were good. Also, the "heat insulation rate" was 52%, the "surface temperature" was 58°C, and the "solar reflectance" was 10.8% in the "near ultraviolet and visible light region (300 nm to 780 nm)" and 49.5% in the "near infrared region (780 nm to 2500 nm)", and good results were obtained.

[0073] The water repellent sheet of Comparative Example 1 used only butyl rubber for the inner layer 11 and did not form the outer layer 12.

[0074] The water repellency (for water) at "θ: static contact angle" was 99°, and the water repellency (for water) at "α: dynamic sliding angle" was 41°. Also, the "heat insulation rate" was 38%, the "surface temperature" was 65°C, the "solar reflectance" was 7.9% in the "near ultraviolet and visible light region (300 nm to 780 nm)" and 6.7% in the "near infrared region (780 nm to 2500 nm)". The results were inferior in terms of contact angle, heat insulation rate, surface temperature, and solar reflectance (near infrared region) compared to the water repellent sheets 1A to 1C.

[0075] For the water-repellent sheet of Comparative Example 2, butyl rubber was used for the inner layer 11, and a mixture with a mass ratio of butyl rubber:ZnO:solvent (toluene) of 17.5:17.5:65 was knife-coated on the outside, dried, and heat-vulcanized to form the outer layer 12.

[0076] The water repellency (water) at "θ: contact angle (static)" was 143°, and the water repellency (water) at "α: sliding angle (dynamic)" was 7°. Also, the "heat insulation rate" was 55%, the "surface temperature" was 56°C, the "solar reflectance" was 57.9% in the "near ultraviolet and visible light region (300 nm to 780 nm)", and 54.4% in the "near infrared region (780 nm to 2500 nm)".

[0077] In the evaluation of "θ: contact angle (static)" and "α: sliding angle (dynamic)", the water-repellent sheets 1A to 1C received higher evaluations than the water-repellent sheet of Comparative Example 1. Therefore, it can be seen that the water-repellent sheets 1A to 1C have superior water-repellent performance compared to Comparative Example 1. As a result, even if a harmful liquid or the like comes into contact with the outside of the water-repellent sheets 1A to 1C, it becomes difficult for the harmful liquid or the like to stop on the surface of the water-repellent sheets 1A to 1C, and it is possible to suppress the adhesion of harmful liquids or the like to the surface of the water-repellent sheets 1A to 1C.

[0078] Thereby, it becomes possible to reduce the labor required for the decontamination work of harmful liquids or the like adhering to the outside of the water-repellent sheets 1A to 1C. Also, since the water-repellent performance is excellent, the protective performance is improved.

[0079] Also, in the evaluation of "heat insulation rate", "surface temperature", and "solar reflectance", the water-repellent sheets 1A to 1C received higher evaluations than the evaluation of Comparative Example 1. Therefore, it can be seen that the water-repellent sheets 1A to 1C have superior performance in solar radiation countermeasures compared to Comparative Example 1. As a result, it becomes possible to suppress the temperature rise inside the water-repellent sheets 1A to 1C.

[0080] [Embodiment 3: Water-Repellent Paint and Water-Repellent Molded Product] In the above embodiment, the water-repellent sheet was described, but here, the water-repellent paint and the water-repellent molded product will be described.

[0081] In Embodiment 1 and Embodiment 2, the rubber layer or resin layer containing the concavo-convex shape-imparting particles, that is, the portion of the outer layer 12, can be used as a water-repellent paint or a water-repellent molded article. That is, the water-repellent paint or the water-repellent molded article has a configuration in which concavo-convex shape particles are contained in a base material that is rubber or resin. In this case, as described above, the shape of the concavo-convex shape-imparting particles is preferably a tetrapod shape, a needle shape, a polygonal shape, or a spherical shape.

[0082] Furthermore, as the water-repellent paint or the water-repellent molded article, the concavo-convex shape-imparting particles are preferably tetrapod-type zinc oxide.

[0083] Furthermore, as the water-repellent paint or the water-repellent molded article, the ratio of the concavo-convex shape-imparting particles to the base material that is rubber or resin is preferably 30 wt% to 70 wt%. More preferably, it is 40 wt% to 60 wt%.

[0084] Furthermore, as the water-repellent paint or the water-repellent molded article, the base material preferably contains an infrared reflective material.

[0085] Furthermore, as the water-repellent paint or the water-repellent molded article, the infrared reflective material is a pigment containing at least one or more metal elements of titanium, manganese, calcium, iron, bismuth, chromium, nickel, and the infrared reflective material is preferably contained in an amount of 5 wt% to 30 wt% with respect to the solid content excluding the infrared reflective material in the base material. More preferably, it is 10 wt% to 20 wt%.

[0086] Furthermore, as the water-repellent paint or the water-repellent molded article, the average particle diameter of the infrared reflective material is preferably 600 nm or more and 1500 nm or less.

[0087] Furthermore, as the water-repellent paint, the thickness of the coating film is preferably 10 μm to 100 μm.

[0088] Furthermore, as a water-repellent paint or water-repellent molded article, the ratio of rubber or resin (base material): ZnO: solvent (toluene, ethyl acetate, etc.) may be 5:5:90 to 10:10:80.

[0089] [Specific Water-Repellent Sheets and Water-Repellent Paints] Next, with reference to FIGS. 10 and 11, specific examples of the above-described water-repellent sheets and water-repellent paints will be described. FIG. 10 is a diagram showing the configuration and evaluation results of each water-repellent sheet from Example 31 to Example 36, and FIG. 11 is a diagram showing the configuration and evaluation results of each water-repellent paint from Example 41 to Example 45.

[0090] In the following examples, BYRON (registered trademark) and HARDREN (registered trademark) shown are registered trademarks of Toyobo Co., Ltd. BYRON (registered trademark) is a polymer polyester resin (amorphous polyester resin (organic solvent-soluble type)) that dissolves in a general-purpose organic solvent, and HARDREN (registered trademark) is a resin obtained by chlorinating or acid-modifying polyolefin. In the figure, for BYRON (registered trademark), a product with the brand name "GK-360" dissolved in MEK / toluene = 1 / 1 to a solid content of 30 wt% was used. In the figure, for HARDREN (registered trademark), a product with the brand name "CY-9122P" dissolved in toluene to a solid content of 30 wt% was used. When BYRON (registered trademark) or HARDREN (registered trademark) is used in water-repellent sheets and water-repellent paints, effects include excellent adhesion to the substrate, as well as merits such as chemical resistance, water resistance, hardness, and long-term durability (heat resistance, weather resistance).

[0091] [Examples 31 to 36: Water-Repellent Sheets] Referring to FIG. 10, each water-repellent sheet from Example 31 to Example 36 will be described. When using an infrared reflective material in combination, the content of the infrared reflective material is preferably 5 wt% to 30 wt%, more preferably 10 wt% to 20 wt%, based on the solid content excluding the infrared reflective material in the total solid content of the sheet composition.

[0092] As an evaluation of "adhesion" in Fig. 10, a test using the cross-cut method (conforming to JIS K5600-5-6) was conducted. Specifically, cuts of 25 squares (2 mm wide, 5×5) were made on the surface of the water-repellent sheet, tape was adhered, and then the surface state after peeling off the tape was observed. As an evaluation of "adhesion", "0" in the classification of the test results in Table 1 of JIS K5600-5-6 was rated as A, "1" as A - rating, "2" as B rating, and "3 or more" as C rating.

[0093] For the water-repellent sheet of Example 31, butyl rubber was used for the base material, and a coating material was knife-coated on the outside, dried, and heat-vulcanized to form an outer layer. The above coating material was mixed so that the mass ratio of rubber:ZnO:solvent (toluene) was 17.5:17.5:65.

[0094] The evaluation results of the water-repellent sheet showed good water repellency (water) at "θ: contact angle (static)" of 150° and "α: sliding angle (dynamic)" of 7°. The evaluation of "adhesion" was "A". The water-repellent sheet of Example 31 has excellent adhesion due to the rubber-based paint coating on the rubber base material.

[0095] For the water-repellent sheet of Example 32, an OPP (biaxially oriented polypropylene) film (P2161 / corona-treated surface) was used for the base material, and a coating material was knife-coated on the outside, heat-dried, and an outer layer was formed. The above coating material was mixed so that the mass ratio of Byron (registered trademark):ZnO:solvent (toluene) was 50:15:35.

[0096] The evaluation results of the water-repellent sheet showed good water repellency (water) at "θ: contact angle (static)" of 140° and "α: sliding angle (dynamic)" of 10°. The evaluation of "adhesion" was "A - ". The water-repellent sheet of Example 32 has excellent adhesion to the OPP film (corona-treated surface).

[0097] The water-repellent sheet of Example 33 used an OPP (biaxially oriented polypropylene) film (P2161 / corona-treated surface) as the base material, and a coating material was knife-coated on the outside thereof, followed by heat drying to form an outer layer. The above coating material was mixed so that the mass ratio of Hardlene (registered trademark): ZnO: solvent (toluene) was 50:15:35.

[0098] The evaluation results of the water-repellent sheet showed good water repellency (water) with a contact angle (static) of θ = 140° and a water repellency (water) with a sliding angle (dynamic) of α = 10°. The evaluation of "adhesion" was "A" - ". By using Hardlene (registered trademark), the water-repellent sheet of Example 33 can enhance the adhesion to PP (polypropylene).

[0099] The water-repellent sheet of Example 34 used a metal plate (SUS plate) as the base material, and a coating material was knife-coated on the outside thereof, followed by heat drying to form an outer layer. The above coating material was mixed so that the mass ratio of Hardlene (registered trademark): ZnO: solvent (toluene) was 50:15:35.

[0100] The evaluation results of the water-repellent sheet showed good water repellency (water) with a contact angle (static) of θ = 141° and a water repellency (water) with a sliding angle (dynamic) of α = 9°. The evaluation of "adhesion" was "A" - ". By using Hardlene (registered trademark), the water-repellent sheet of Example 34 can enhance the adhesion to metal.

[0101] The water-repellent sheet of Example 35 used a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) as the base material, and a coating material was knife-coated on the outside thereof, followed by heat drying to form an outer layer. The above coating material was mixed so that the mass ratio of Byron (registered trademark): ZnO: solvent (toluene) was 50:15:35.

[0102] The evaluation results of the water-repellent sheet showed good water repellency (for water) with a contact angle (static) of θ = 143° and a sliding angle (dynamic) of α = 8°. The evaluation of "adhesion" was " - A

[0103] The water-repellent sheet of Example 35 had excellent adhesion to the PET film (corona-treated surface).

[0104] The evaluation results of the water-repellent sheet showed good water repellency (for water) with a contact angle (static) of θ = 144° and a sliding angle (dynamic) of α = 9°. The evaluation of "adhesion" was "A". The water-repellent sheet of Example 36 had excellent adhesion because the rubber-based paint was impregnated and coated on the fabric.

[0105] [Examples 41 - 45: Water-Repellent Paint] Next, with reference to FIG. 11, specific examples of the water-repellent paint will be described. Examples of the coating method include known methods such as spray coating, spin coating, and brush coating. The drying conditions can be either natural drying or heat drying. When using an infrared reflective material in combination, the content of the infrared reflective material is preferably 5 wt% - 30 wt%, more preferably 10 wt% - 20 wt%, based on the solid content of the paint composition excluding the infrared reflective material.

[0106] In the following Examples 41 to 45, spray coating was performed on a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface). When using BYK (registered trademark) or Hardlene (registered trademark) as the paint resin, effects such as adhesion to the substrate, chemical resistance, water resistance, hardness, and long-term durability (heat resistance, weather resistance) can be achieved.

[0107] The water-repellent paint of Example 41 was mixed so that the mass ratio of rubber:ZnO:solvent (toluene) was 10:10:80. This water-repellent paint was spray-coated onto a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) and air-dried.

[0108] The evaluation results of the water-repellent paint showed good water repellency (water) with a contact angle (static) of θ = 143° and a sliding angle (dynamic) of α = 8°. The evaluation of "adhesion" was "B".

[0109] The water-repellent paint of Example 42 was mixed so that the mass ratio of BYK (registered trademark):ZnO:solvent (toluene) was 20:6:74. This water-repellent paint was spray-coated onto a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) and air-dried.

[0110] The evaluation results of the water-repellent paint showed good water repellency (water) with a contact angle (static) of θ = 142° and a sliding angle (dynamic) of α = 7°. The evaluation of "adhesion" was "B".

[0111] The water-repellent paint of Example 43 was mixed so that the mass ratio of Hardlen (registered trademark):ZnO:solvent (toluene) was 20:6:74. This water-repellent paint was spray-coated onto a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) and air-dried.

[0112] The evaluation results of the water-repellent paint showed good water repellency (water) with a contact angle (static) of θ = 140° and a sliding angle (dynamic) of α = 10°. The evaluation of "adhesion" was "B".

[0113] The water-repellent paint of Example 44 was mixed so that the mass ratio of urethane:ZnO:solvent (toluene) was 10:10:80. This water-repellent paint was spray-coated onto a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) and air-dried.

[0114] The evaluation results of the water-repellent paint showed good water repellency (water) with a contact angle (static) of 141° for "θ: contact angle (static)" and a sliding angle (dynamic) of 9° for "α: sliding angle (dynamic)". The evaluation of "adhesion" was "B".

[0115] The water-repellent paint of Example 45 was mixed so that the mass ratio of polyvinyl chloride: ZnO: solvent (toluene) was 10:10:80. This water-repellent paint was spray-coated on a PET (polyethylene terephthalate) film (PET E5100 / corona-treated surface) and allowed to dry naturally.

[0116] The evaluation results of the water-repellent paint showed good water repellency (water) with a contact angle (static) of 140° for "θ: contact angle (static)" and a sliding angle (dynamic) of 10° for "α: sliding angle (dynamic)". The evaluation of "adhesion" was "B".

[0117] [Embodiment 4: Application Examples of Specific Water-Repellent Sheets, Water-Repellent Paints, and Water-Repellent Molded Articles] Next, specific application examples of the above-described water-repellent sheets, water-repellent paints, and water-repellent molded articles will be described.

[0118] When the above-described water-repellent sheets, water-repellent paints, and water-repellent molded articles are used for water pipes, water storage tanks, and bridges, water and snow adhesion can be prevented.

[0119] When the above-described water-repellent sheets, water-repellent paints, and water-repellent molded articles are used for outdoor tools (awning materials, tent materials, tarps), umbrellas, wetting and soiling prevention, and solar radiation countermeasures (combined with infrared reflective materials) can be achieved.

[0120] When the above-described water-repellent sheet is used for wrapping materials (automobile bodies, building materials, etc.), wetting and soiling prevention, and solar radiation countermeasures (combined with infrared reflective materials) can be achieved.

[0121] When the above-described water-repellent sheets, water-repellent paints, and water-repellent molded articles are used for automobile bodies, building materials, etc., wetting and soiling prevention, and solar radiation countermeasures (combined with infrared reflective materials) can be achieved.

[0122] When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are used for clothing, sports and outdoor goods, it is possible to prevent wetting and soiling and take measures against solar radiation (combined with an infrared reflecting material).

[0123] When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are used for areas around water (toilets, washbasins, bathtubs), it is possible to prevent wetting and soiling (reduce the frequency of cleaning, reduce bad odors).

[0124] When the above-mentioned water-repellent paint is used for medical instruments (catheters, wires, etc.), it is possible to improve the slipperiness.

[0125] When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are used for medical supplies (aprons, waterproof cases, etc.), it is possible to prevent wetting and soiling.

[0126] [More specific usage modes] More specific usage modes of the water-repellent sheet, water-repellent paint, and water-repellent molded product will be described below. When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are applied to the bottom of a ship, if the bottom surface is made water-repellent, a thin air film will form between the bottom surface of the ship and the seawater, and the resistance due to the viscosity of water will be significantly reduced, enabling an increase in the sailing speed.

[0127] When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are applied to a toilet, urine will drop without adhering to the toilet, making it difficult for dirt and odors to stick, and significantly reducing the frequency of cleaning. When the water-repellent sheet, water-repellent paint, and water-repellent molded product are applied to areas around water, the same effects can be achieved for water-related supplies such as washbasins, sinks, bathtubs, tiles, or the surrounding floors, ceilings, and walls.

[0128] When the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product are used for the bodies of vehicles such as cars, motorcycles, bicycles, airplanes, the outer walls of buildings, furniture, tableware, shoes, etc., it is possible to prevent dirt and wetting like an umbrella.

[0129] For metal surfaces that require corrosion resistance, such as the interior of pipes and the surface of steel frameworks, rust prevention is generally achieved by painting. However, since paint has a limited lifespan, corrosion gradually progresses due to water droplets adhering to the surface. When the above-mentioned water-repellent sheets, water-repellent paints, and water-repellent molded products are used on metal surfaces that require corrosion resistance, such as the interior of pipes and the surface of steel frameworks, if the surface is made water-repellent, water droplets will not adhere, so the corrosion resistance can be dramatically improved.

[0130] When frosting occurs on the fins of a heat exchanger, on a hydrophilic surface, it exists in the form of a water film, causing a decrease in the air volume passing between the fins and a reduction in heat exchange capacity. When the above-mentioned water-repellent sheets, water-repellent paints, and water-repellent molded products are used on the fins of a heat exchanger, the condensed water generated on the fins exists in a hemispherical shape on the water-repellent surface. Therefore, the contact area between the condensed water and the fins is relatively small, and the time required for the condensed water to freeze becomes longer. That is, by making the surface of the fins of the heat exchanger water-repellent, the continuous operation time of the heat exchanger can be extended.

[0131] Normally, there are slightly gaps in the fastener part due to its structure, so water ingress may occur from here. When the above-mentioned water-repellent sheets, water-repellent paints, and water-repellent molded products are used on the fastener part of a waterproof garment, the fastener is given water-repellent properties, and water ingress can be significantly reduced.

[0132] A portable wooden canoe becomes heavier due to water ingress, increasing the burden of transportation. When the above-mentioned water-repellent sheets, water-repellent paints, and water-repellent molded products are used on a portable wooden canoe, the surface of the wooden canoe is given water-repellent properties, and since there is no water ingress, an increase in weight can be prevented.

[0133] For a bridge at sea, since the bridge girder is in contact with seawater, its lifespan is short due to the corrosion of steel frameworks and concrete. When the above-mentioned water-repellent sheets, water-repellent paints, and water-repellent molded products are applied to a bridge at sea, the bridge girder is given water-repellent properties, and a longer lifespan can be achieved.

[0134] By applying the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product to laminates and packaging materials, such as tablecloths, napkins, aprons, table covers, floor mats, wall coverings, wallpapers, labels, release papers, tags, chair covers, waterproof sheets, umbrellas, ski wear, building materials, bed covers, shoe uppers, shoe covers, waterproof clothing, water-repellent films, water-repellent sheets, etc., and packaging materials used for packaging foods, beverages, pharmaceuticals, cosmetics, chemicals, etc., it becomes possible to enhance water repellency.

[0135] In addition, by applying the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product to heat exchangers and antennas in cold regions, frosting and icing can be prevented. Also, by applying the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product to sports wear and sports equipment, water resistance in swimwear can be reduced, and in the case of skis, an improvement in slipperiness can be expected.

[0136] As described above, the above-mentioned water-repellent sheet, water-repellent paint, and water-repellent molded product can be suitably applied to water pipes, water storage tanks, bridges, ship bottoms, awnings, tents, tarps, umbrellas, automobile bodies, building materials, clothing, sports and outdoor supplies, plumbing supplies (such as sinks, bathtubs, toilets, etc.), medical devices (such as catheter wires, etc.), medical supplies (such as aprons, waterproof cases, etc.), or ostomy-related products.

[0137] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0138] 1 Water-repellent sheet, 11 Rubber layer, 12 Outer layer.

Claims

1. A water-repellent sheet having an inner side and an outer side, an inner layer located on the inner side, an outer layer laminated on the inner layer and located on the outer side, comprising: the outer layer contains particles imparting an uneven shape, the inner layer is a rubber layer, a resin layer, a fabric layer, or a metal layer, a water-repellent sheet.

2. The shape of the particles imparting the uneven shape is a tetrapod shape, a needle shape, a polygonal shape, or a spherical shape, The water-repellent sheet according to Claim 1.

3. The particles imparting the uneven shape are tetrapod-type zinc oxide, The water-repellent sheet according to Claim 1.

4. The solid content ratio of the particles imparting the uneven shape to the total solid content of the outer layer is 40 wt% to 60 wt%, The water-repellent sheet according to Claim 1.

5. The outer layer further contains an infrared reflective material, The water-repellent sheet according to Claim 1.

6. The infrared reflective material is a pigment containing at least one metal element of titanium, manganese, calcium, iron, bismuth, chromium, nickel, and the infrared reflective material is contained in an amount of 5 wt% to 30 wt% based on the solid content of the outer layer excluding the infrared reflective material, The water-repellent sheet according to Claim 5.

7. The average particle diameter of the infrared reflective material is 600 nm or more and 1500 nm or less, The water-repellent sheet according to Claim 5.

8. On the surface of the inner layer opposite to the surface on which the outer layer is laminated, a fabric and a second inner layer are laminated in the described order, The second inner layer is a rubber layer, a resin layer, a fabric layer, or a metal layer, The water-repellent sheet according to Claim 1.

9. The fabric is a woven fabric, a knitted fabric, or a non-woven fabric, The water-repellent sheet according to Claim 8.

10. Different types of materials are used for the inner layer and the second inner layer, The water-repellent sheet according to Claim 8.

11. The water-repellent sheet is used for a water pipe, a water storage tank, a bridge, a ship bottom, a roof, a tent, a tarp, an umbrella, an automobile body, building materials, clothing, sports and outdoor supplies, water-related supplies (washing face, bathtub, toilet, etc.), medical instruments (catheter wire, etc.), medical tools (apron, waterproof case, etc.), or ostomy-related products, The water-repellent sheet according to Claim 1.

12. A base material, particles imparting an uneven shape contained in the base material, comprising: the base material is rubber or resin, a water-repellent paint.

13. The shape of the particles imparting the uneven shape is a tetrapod shape, a needle shape, a polygonal shape, or a spherical shape, The water-repellent paint according to claim 12.

14. The concavo-convex shape-imparting particles are tetrapod-type zinc oxide. The water-repellent paint according to claim 12.

15. The ratio of the concavo-convex shape-imparting particles to the base material is 40 wt% to 60 wt%. The water-repellent paint according to claim 12.

16. The base material further contains an infrared reflective material. The water-repellent paint according to claim 12.

17. The infrared reflective material is a pigment containing at least one of the metal elements of titanium, manganese, calcium, iron, bismuth, chromium, and nickel, and the infrared reflective material is contained in an amount of 5 wt% to 30 wt% based on the solid content of the base material excluding the infrared reflective material. The water-repellent paint according to claim 16.

18. The average particle diameter of the infrared reflective material is 600 nm or more and 1500 nm or less. The water-repellent paint according to claim 16.

19. The water-repellent paint is used for water pipes, water storage tanks, bridges, ship bottoms, awnings, tents, tarps, umbrellas, automobile bodies, building materials, clothing, sports and outdoor supplies, water-related supplies (washing face, bath, toilet, etc.), medical instruments (catheters, wires, etc.), medical tools (aprons, waterproof cases, etc.), or ostomate-related products. The water-repellent paint according to claim 12.

20. A base material, concavo-convex shape-imparting particles contained in the base material, are provided, The base material is rubber or resin. Water-repellent molded product.

21. The shape of the concavo-convex shape-imparting particles is tetrapod-shaped, needle-shaped, polygonal, or spherical. The water-repellent molded product according to claim 20.

22. The concavo-convex shape-imparting particles are tetrapod-type zinc oxide. The water-repellent molded product according to claim 20.

23. The ratio of the concavo-convex shape-imparting particles to the base material is 40 wt% to 60 wt%. The water-repellent molded product according to claim 20.

24. The base material further contains an infrared reflective material. The water-repellent molded product according to claim 20.

25. The infrared reflective material is a pigment containing at least one of the metal elements of titanium, manganese, calcium, iron, bismuth, chromium, and nickel, and the infrared reflective material is contained in an amount of 5 wt% to 30 wt% based on the solid content of the base material excluding the infrared reflective material. The water-repellent molded product according to claim 24.

26. The average particle diameter of the infrared reflective material is 600 nm or more and 1500 nm or less. The water-repellent molded product according to claim 24.

27. The water-repellent molded article is used for a water distribution pipe, a water storage tank, a bridge, a ship bottom, a roof, a tent, a tarp, an umbrella, an automobile body, building materials, clothing, sports and outdoor goods, water-related goods (washing face, bath, toilet, etc.), medical instruments (catheter wires, etc.), medical tools (aprons, waterproof cases, etc.), or ostomy-related products, the water-repellent molded article according to claim 20.

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