Water-repellent material, water-repellent component, and method for manufacturing a water-repellent material

Abstract

To provide a highly durable water-repellent object having high water repellency and capable of preventing separation of a water-repellent part, a water-repellent component including the water-repellent object, and a method for producing the water-repellent object.SOLUTION: A water-repellent object 1 comprises a base material (metal film 3) having a dip-and-bump structure 30, and a coating film 4 covering the dip-and-bump structure 30. The coating film 4 has a water-repellent part 6 containing a fluorine compound, and an adhesion part 5 firmly adhering to the base material (metal film 3). The adhesion part 5 is a mixture containing silica and yttria.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a water-repellent body, a water-repellent component, and a method for manufacturing a water-repellent body.

Background Art

[0002] Conventionally, in order to prevent adhesion of water droplets, dust, etc. to the surface of an article, a water-repellent body having a water-repellent film formed on the surface of the article is known (for example, Patent Document 1). Such a water-repellent body has a large contact angle with water and can easily repel water droplets, etc., and is therefore used for automobile bodies, camera lenses, etc. that require water repellency.

[0003] Patent Document 1 describes a water-repellent body in which a film containing a fluororesin, hydrophilic silica particles, and hydrophobic silica particles is formed on a substrate. The fluororesin and the hydrophilic silica particles have a role of adhering the substrate and the film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The water-repellent body of Patent Document 1 has a problem that the adhesion between the water-repellent film and the substrate is weak, so the film is likely to peel off from the substrate due to friction or the like, and the water repellency is easily lost.

[0006] Therefore, there is a demand for a highly durable water-repellent body that has high water repellency and can suppress peeling of the coating (water-repellent part).

Means for Solving the Problems

[0007] One embodiment of the water-repellent material according to the present invention comprises a substrate having an uneven structure and a coating covering the uneven structure, wherein the coating has a water-repellent portion containing a fluorine compound and an adhesive portion that adheres to the substrate, and the adhesive portion is a mixture containing silica and yttria.

[0008] One embodiment of the water-repellent component according to the present invention comprises a water-repellent body and a material to be coated on which the water-repellent body is formed.

[0009] One embodiment of the method for producing a water-repellent material according to the present invention includes a step of forming an uneven structure on the surface of a substrate, a step of forming an adhesion portion on the surface of the uneven structure consisting of a mixture containing silica and yttria, and a step of forming a water-repellent portion on the surface of the adhesion portion consisting of a water-repellent portion containing a fluorine compound. [Effects of the Invention]

[0010] According to embodiments of the present invention, it is possible to provide a highly durable water-repellent body that has high water repellency and can suppress peeling of the water-repellent portion, a water-repellent component equipped with the water-repellent body, and a method for manufacturing the water-repellent body. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-section of the water-repellent component. [Figure 2] This is an SEM image showing a surface with an uneven, textured structure. [Figure 3] This is an SEM image showing a longitudinal section of a metal coating. [Figure 4] This diagram illustrates a method for manufacturing water-repellent materials and water-repellent components. [Figure 5] This is a longitudinal cross-section of the water-repellent material. [Figure 6] This is a diagram illustrating a method for manufacturing a water-repellent material. [Figure 7] This figure shows the water contact angle in the embodiment. [Figure 8] This figure shows the water sliding angle in the example. [Modes for carrying out the invention]

[0012] The embodiments of the water-repellent material according to the present invention will be described below with reference to the drawings. The embodiments described below are illustrative examples for explaining the present invention and do not limit the present invention to these embodiments only. Therefore, the present invention can be implemented in various forms without departing from its essence.

[0013] [First Embodiment] Figure 1 is a longitudinal cross-sectional view of a water-repellent component 100 according to this embodiment. The water-repellent component 100 comprises a water-repellent body 1 and a material to be coated 2. The water-repellent component 100 is not particularly limited, but is a component of various products that require water repellency. The material to be coated 2 is a metal such as aluminum or iron, or glass, ceramics, etc. In Figure 1, the material to be coated 2 is a single layer, but is not limited to this, and may be a laminate of multiple layers, in which case each layer may be the same or different. The material to be coated 2 may be, for example, the body of an automobile or a door handle. The water-repellent body 1 is formed on the surface of the material to be coated 2.

[0014] The water-repellent body 1 comprises a metal coating 3 (an example of a substrate) and a coating 4. The metal coating 3 is formed of a metal such as titanium or chromium, and its thickness is 1 μm to 5 μm. The metal coating 3 has an uneven surface 30, and the uneven surface 30 is formed on the surface of the metal coating 3 that is opposite to the surface that comes into contact with the material to be coated 2.

[0015] Figure 2 is an SEM (Scanning Electron Microscope) image showing the surface of the uneven structure 30, and Figure 3 is an SEM image showing a longitudinal section of the metal coating 3. As shown in Figures 2 and 3, the metal coating 3 is a columnar crystal with pointed tips, and this tip portion is defined as the uneven structure 30. The metal coating 3 in Figures 2 and 3 is formed of chromium, but it may be formed of other metals.

[0016] The height difference between the convex part and the concave part in the concavo-convex structure 30 is preferably, for example, 10 nm to 5 μm. Specifically, the height difference between the convex part and the concave part is the difference between the height of the apex of the convex part and the height of the bottom of the concave part. If the height difference between the convex part and the concave part is too large, the strength of the concavo-convex structure 30 will decrease and the concavo-convex structure 30 will be likely to collapse. On the other hand, if the height difference between the convex part and the concave part is too small, the high water repellency performance described later cannot be obtained. Therefore, this difference is preferably 100 nm to 3 μm. Since such a concavo-convex structure 30 is a fine structure, it is likely to collapse due to contact with a human hand or the like. However, by forming the concavo-convex structure 30 with a metal, the hardness is increased compared to the concavo-convex structure conventionally formed with a resin or the like, so that the durability can be improved.

[0017] As shown in FIG. 1, the concavo-convex structure 30 is covered with a film 4. The film 4 has an adhesion part 5 that adheres to the concavo-convex structure 30 and a water repellent part 6 formed on the surface of the adhesion part 5. Therefore, on the surface of the concavo-convex structure 30, the film 4 is formed such that the adhesion part 5 and the water repellent part 6 are laminated in this order.

[0018] The adhesion part 5 is a mixture containing silica and yttria. Since the silicon contained in the adhesion part 5 has a high affinity with the fluorine contained in the water repellent part 6 described later, a stable bond occurs between them, and the adhesion part 5 and the water repellent part 6 adhere to each other. Therefore, it is possible to suppress the peeling of the water repellent part 6 from the concavo-convex structure 30.

[0019] Yttria contained in the adhesion part 5 can improve the hardness by adding it to silica. Therefore, compared with the hydrophilic silica particles usually used as an adhesive, the adhesion part 5 has high hardness and high durability. Therefore, by covering the surface of the uneven structure 30 with the adhesion part 5, the uneven structure 30 can be protected by the adhesion part 5. As a result, the durability of the uneven structure 30 is further improved. The content rate of yttria in the adhesion part 5 is not particularly limited. For example, the lower limit value is preferably 1.0 mol% or more, more preferably 1.1 mol% or more, and the upper limit value is preferably less than 10 mol%, more preferably less than 6 mol% from the viewpoint of the adhesion of the uneven structure 30. The adhesion part 5 preferably has a thickness of 5 nm to 90 nm and is preferably formed uniformly on the surface of the uneven structure 30.

[0020] Some of the yttrium atoms contained in the adhesion part 5 Group 4 elements may be replaced by the atoms of Group 4 elements is not particularly limited. For example, it may be at least one selected from the group consisting of titanium, zirconium, and hafnium, and zirconium is particularly preferable. These elements may be used singly or in combination. When some of the yttrium atoms are replaced by these atoms, the bond of the atoms in the adhesion part 5 becomes stronger. Therefore, it is considered that the hardness of the adhesion part 5 is higher than that when some of the yttrium atoms are not replaced. As a result, scratch resistance and the like can be imparted to the uneven structure 30, and the durability can be improved.

[0021] In the adhesion part 5, the yttrium atom Group 4 elements substitution rate ( Group 4 elements content rate of the atoms of

[0022] Furthermore, some of the oxygen atoms in the yttria may be replaced with nitrogen atoms. Since the bonding strength between nitrogen atoms and yttrium atoms is higher than that between oxygen atoms and yttrium atoms, replacing some of the oxygen atoms in the yttria with nitrogen atoms improves the strength of the adhesion portion 5. This also improves the strength of the water-repellent body 1 that has the adhesion portion 5.

[0023] In the contact area 5, the substitution rate (nitrogen atom content) in which some of the oxygen atoms in yttria are replaced by nitrogen atoms is not particularly limited as long as it is greater than 0, but it may be 1 atomic%, and the upper limit may be, for example, 10 atomic%, 5 atomic%, 3 atomic%, or 2 atomic%.

[0024] A water-repellent portion 6 is formed on the surface of the adhesion portion 5. The water-repellent portion 6 contains a fluorine compound. The fluorine compound preferably has a difluoromethyl group, and may also contain silicon, oxygen, etc. As described above, the water-repellent portion 6 adheres to the adhesion portion 5 by forming a stable bond between the silicon atoms of the adhesion portion 5 and the fluorine atoms of the water-repellent portion 6. Furthermore, since the bond between the fluorine atoms and carbon atoms contained in the water-repellent portion 6 is stable, the forces acting between these molecules are weak, and the surface free energy of the water-repellent portion 6 is low. For this reason, the water-repellent portion 6 exhibits water repellency. The water-repellent portion 6 preferably has a thickness of 5 nm to 90 nm and is preferably formed uniformly on the surface of the adhesion portion 5 (or uneven structure 30).

[0025] Here, when a water droplet adheres to the surface of the water-repellent body 1, the contact area between the water-repellent body 1 and the water droplet is the contact area between the tip of the uneven structure 30 and the water droplet. Therefore, by having the uneven structure 30, the water-repellent body 1 can reduce the contact area between the water droplet and the water-repellent body 1. Furthermore, the water-repellent portion 6, which has water-repellency properties, is formed on the surface of the uneven structure 30, thereby imparting high water repellency to the water-repellent body 1. In other words, the high water repellency of the water-repellent body 1 in this embodiment is achieved by the combination of the uneven structure 30 and the water-repellent portion 6. Since the water-repellent body 1 has the effect of suppressing the spreading of water wetting on its surface, it can be applied, for example, to the surface of a glass lens or the surface of a human presence sensor mounted on an automobile.

[0026] [Method for manufacturing water-repellent material] Next, the manufacturing method of the water-repellent component 100 and the water-repellent body 1 will be explained using Figure 4. First, a surface uneven structure formation step is performed to form a metal coating 3 and an uneven structure 30 on the surface of the material to be coated 2. The surface uneven structure formation step is performed by sputtering, and titanium, chromium, etc. can be used as the target. If the gas pressure of the sputtering gas in the surface uneven structure formation step is too low, a smooth metal coating 3 will be formed on the surface of the material to be coated 2, and the surface uneven structure 30 cannot be obtained. Therefore, in the surface uneven structure formation step, it is preferable to form the surface uneven structure 30 under medium to high pressure (for example, 1 Pa or higher). In this way, by forming the surface uneven structure 30 using the sputtering method, the strength of the surface uneven structure 30 can be increased.

[0027] In the process of forming an uneven structure, the method of sputtering other than the method described above is not particularly limited, and may be the same as or similar to a general sputtering method.

[0028] Next, an adhesion portion formation step is performed to form adhesion portions 5 on the surface of the uneven structure 30. The adhesion portion formation step is not particularly limited, but can be performed by, for example, vacuum deposition, sputtering, ion plating, or ion beam deposition, which are classified as physical vapor deposition, or by atomic layer deposition or plasma CVD, which are classified as chemical vapor deposition. Vapor deposition tends to produce films with a fast film formation rate but low hardness (soft). Sputtering tends to produce films with a slow film formation rate but high hardness (hard). In the adhesion portion formation step in this embodiment, it is preferable to use sputtering from the viewpoint of improving the strength of the uneven structure 30. Furthermore, sputtering allows for the uniform formation of adhesion portions 5 on the surface of the uneven structure 30.

[0029] In the adhesion formation process, a mixture of silica and yttria can be used as the target. This allows for the uniform formation of the adhesion 5 on the surface of the uneven structure 30, making it possible to adhere the water-repellent portion 6 to the uneven structure 30. Note that some of the yttrium atoms in the mixture are zirconium atoms, etc. Group 4 elements It may be substituted with an atom of the same type.

[0030] Furthermore, in order to replace some of the oxygen atoms in the yttria contained in the contact area 5 with nitrogen atoms, film formation may be carried out, for example, by sputtering in an atmosphere in which nitrogen is added to argon (reactive sputtering method).

[0031] In the adhesion formation process, the method of sputtering is not particularly limited, and for example, it may be the same as or similar to a general sputtering method. Furthermore, from the viewpoint of manufacturing efficiency, it is preferable that the film formation speed by the sputtering method is not too slow, and from the viewpoint of the hardness of the adhesion portion 5, it is preferable that the film formation speed by the sputtering method is not too fast.

[0032] Finally, a water-repellent portion forming step is performed to form a water-repellent portion 6 on the surface of the adhesion portion 5. The water-repellent portion forming step is not particularly limited, but can be performed by, for example, a plasma gas treatment method. As the plasma gas treatment method, atmospheric pressure plasma treatment or corona treatment can be used.

[0033] The fluorine compounds used in the water-repellent portion formation process can include, for example, perfluorocarbons such as carbon tetrafluoroethylene and perfluorocyclobutane, hydrofluorocarbons such as trifluoromethane and difluoromethane, sulfur hexafluoride, and nitrogen trifluoride. When these gases are plasma-activated, fluorine-based active species are formed, and the coating derived from these fluorine-based active species held in the adhesion portion 5 reduces the surface free energy of the water-repellent body 1. This makes it possible to impart high water repellency to the water-repellent body 1.

[0034] Furthermore, the method for performing plasma gas treatment in the water-repellent portion formation process is not particularly limited, and may be the same as or similar to general plasma gas treatment. Also, the uneven structure formation process, the adhesion portion formation process, and the water-repellent portion formation process may be performed in a series of processes.

[0035] [Second Embodiment] The water-repellent body 1 according to the second embodiment will be described with reference to Figure 5. The resin film 7 (an example of a substrate) having an uneven structure 70 is a flexible resin film. In this embodiment, the uneven structure 70 is formed continuously on the surface of the resin film 7, as shown in Figure 5. Adhesion portions 5 and water-repellent portions 6 are formed on the surface of the uneven structure 70 in that order. The other configurations are the same as in the first embodiment, so the description of similar configurations will be omitted.

[0036] The uneven structure 70 formed by the resin film 7 is less strong and more prone to collapse compared to the uneven structure 30 formed by metal or the like in the first embodiment. Therefore, in this embodiment, the strength of the uneven structure 70 is maintained by the adhesive portion 5 that covers the uneven structure 70.

[0037] The resin film 7 is not particularly limited as long as it is a flexible resin, but for example, thermoplastic resins, thermosetting resins, or photocurable resins can be used. Examples of thermoplastic resins include polyester resins such as polyethersulfone resins, polycarbonate resins, acrylic resins, polyethylene terephthalate resins, polyethylene naphthalate resins, unsaturated polyester resins, polyolefin resins, norbornene resins, polyimide resins, polyamide resins, polyimidoamide resins, polyarylate resins, polysulfone resins, and polyetherimide resins. Examples of thermosetting resins include phenolic resins, epoxy resins, and urethane resins. Examples of photocurable resins include acrylic resins and epoxy resins. From the viewpoint of moldability of the uneven structure 70, it is preferable to use thermoplastic resins, thermosetting resins, or photocurable resins as the resin film 7. In addition, a heat-resistant resin may be selected depending on the performance of the water-repellent body 1.

[0038] The thickness of the resin film 7 is, for example, 100 nm to 1 mm. By adhering such a thin resin film 7 to the surface of an object (a material to be coated) to which water repellency is to be applied, it becomes possible to apply water repellency even to objects with complex shapes. High water repellency can be applied to objects with large surface areas, making it possible to apply water repellency to a variety of items. Furthermore, by connecting multiple resin films 7 in a continuous line, high water repellency can be applied to the roll-shaped film itself.

[0039] The resin film 7 may or may not be colored. Coloring the resin film 7 allows for the coloring of the water-repellent body 1, thereby increasing the selectivity of the appearance design of the water-repellent body 1. Furthermore, the resin film 7 may be transparent. Because it is permeable, fixing the resin film 7 to the surface of the material to be coated does not hinder the color development of the material. Therefore, the water-repellent material 1 can be easily applied to existing products, making it possible to impart water repellency to various items.

[0040] The resin film 7 may be fixed to the surface of the material to be coated with an adhesive. The adhesive is not particularly limited as long as it can fix the resin film 7, but for example, an acrylic resin or a polyester resin may be used.

[0041] [Method for manufacturing water-repellent material] Next, the manufacturing method of the water-repellent material 1 will be explained using Figure 6. First, a textured structure formation step is performed to form a textured structure 70 on the surface of the resin film 7. The textured structure formation step is performed by pressing a mold 8 onto the resin film 7 and transferring the textured structure 70.

[0042] The mold 8 is, for example, a mold, and is formed to transfer the uneven structure 70. The mold 8 is processed by etching, laser, electroforming, etc., so that it can form an uneven structure 70 similar to the uneven structure 30. Since the uneven structure 70 is a very fine structure, it is preferable to create the mold 8 using electroforming, which can form such an uneven structure 70 with high precision. In the first embodiment, it is preferable to use the uneven structure 30 formed by the sputtering method to create the mold 8.

[0043] Transfer can be performed by thermal imprinting, UV imprinting, nanocasting, reversal imprinting, roll-to-roll, etc. Thermal imprinting involves thermal cycling, resulting in lower production efficiency, but it can process a wide variety of materials. UV imprinting, on the other hand, has the advantage of efficient transfer in a short time. In this embodiment, any of these methods can be used.

[0044] When creating a resin film 7 using a thermoplastic resin, the thermoplastic resin, which has been heated and softened, is clamped in a mold 8 (the mold 8 is pressed against the thermoplastic resin). After that, the thermoplastic resin is cooled and the mold is opened to obtain a resin film 7 having an uneven structure 70. When creating a resin film 7 using a thermosetting resin, it is preferable to heat the liquid thermosetting resin after clamping it in a mold 8. After the thermosetting resin hardens due to heating, the mold is opened to obtain a resin film 7 having an uneven structure 70. When creating a resin film 7 using a photocurable resin, it is preferable to apply the liquid thermosetting resin to the surface of the material to be coated, and then cure the photocurable resin by irradiating it with light while clamped in a transparent mold 8. After that, the mold is opened to obtain a resin film 7. Alternatively, the liquid photocurable resin may be irradiated with light, and the photocurable resin, which has hardened to a certain extent, may be clamped in an opaque mold 8, the mold is opened, and then irradiated with light again to completely harden it.

[0045] Next, an adhesion portion forming step is performed to form an adhesion portion 5 on the surface of the uneven structure 70, and then a water-repellent portion forming step is performed to form a water-repellent portion 6 on the surface of the adhesion portion 5. The adhesion portion forming step and the water-repellent portion forming step are the same as in the first embodiment, so a detailed explanation is omitted.

[0046] The water-repellent body 1, on which the adhesive portion 5 and the water-repellent portion 6 are formed on the resin film 7, may be fixed to the surface of the material to be coated. Fixation may be performed by applying an adhesive, for example, an acrylic resin or a polyester resin, to the surface of the material to be coated and fixing the water-repellent body 1 to that surface. As a result, the adhesive adheres the material to be coated and the water-repellent body 1, fixing the water-repellent body 1 to the surface of the material to be coated, and imparting the high water-repellency of the water-repellent body 1 to the material to be coated. The adhesive may also be applied to the surface of the water-repellent body 1 that comes into contact with the material to be coated. Note that if a liquid thermosetting resin or a photocurable resin is applied to the material to be coated, and then the mold is clamped and the resin is cured by heating or light irradiation, the resin film 7 will be fixed to the surface of the material to be coated as the resin hardens, so fixing with an adhesive or the like is unnecessary.

[0047] [Examples] The following describes embodiments of this disclosure. However, this disclosure is not limited to the following embodiments.

[0048] (Example 1) Example 1 was prepared using the manufacturing method for the water-repellent material of this disclosure. First, as a surface texture formation step, a metal film 3 having a surface texture 30 was formed on the surface of the target material 2 by sputtering using a sputtering apparatus (E-200S, Canon Anelva Corporation). A DC power supply was used in the surface texture formation step, with an input power of 150W. Chromium was used as the target for forming the metal film 3, and argon was used as the sputtering gas. Sputtering was performed under medium-high pressure, and the metal film 3 and surface texture 30 were obtained by heating the substrate in the range of room temperature to 200°C. The thickness of the obtained metal film 3 was 2.5 μm.

[0049] Next, as an adhesion zone formation process, an adhesion zone 5 was formed on the surface of the uneven structure 30 by sputtering using a sputtering apparatus (E-200S, Canon Anelva Corporation). A high-frequency power supply was used in the adhesion zone formation process, with an input power of 75W. A ceramic mixture of silica and yttria (sintering density: 65%~98%) was used as the target for forming the adhesion zone 5. This ceramic was obtained by hot pressing using a multi-purpose high-temperature furnace (High Multi 5000, Fuji Denpa Kogyo Co., Ltd.). Argon was used as the sputtering gas, and the adhesion zone 5 was obtained by forming a film at room temperature under low pressure. The thickness of the obtained adhesion zone 5 was 30 nm.

[0050] Finally, as a water-repellent layer formation step, a water-repellent layer 6 was formed on the surface of the adhesion layer 5 by plasma gas treatment using a reactive ion etching apparatus (RIE-400iPB, Samco Co., Ltd.). The ICP power was set to 100-1000W, and perfluorocyclobutane and oxygen were used as gases. The water-repellent layer 6 was obtained by processing at a gas pressure of 1-10Pa and a temperature range of room temperature to 70°C. The thickness of the obtained water-repellent layer 6 was 50 nm.

[0051] (Example 2) In the adhesion formation process, a ceramic mixture of silica, zirconia, and yttria was used as the target for forming the adhesion portion 5, and argon and nitrogen were used as the sputtering gases. Except for these differences, the water-repellent material 1 was obtained in the same manner as in Example 1. In Example 2, the substitution rate of yttrium atoms with zirconium atoms was set to 5-20 mol%. Additionally, some of the oxygen atoms in the yttria were substituted with nitrogen atoms. The ceramics used in the preparation of Example 2 (sintering density: 65%-98%) were prepared in the same manner as in Example 1.

[0052] (Comparative Example 1) A water-repellent material 1 was obtained in the same manner as in Example 2, except that a ceramic mixture of zirconia and yttria was used as the target for forming the adhesion portion 5. In Comparative Example 1, the substitution rate of yttrium atoms with zirconium atoms was 5 mol%. In addition, some of the oxygen atoms in the yttria were substituted with nitrogen atoms. The ceramics used to prepare Comparative Example 1 (sintering density: 65%~98%) were prepared in the same manner as in Example 1.

[0053] (Comparative Example 2) Water-repellent material 1 was obtained in the same manner as in Comparative Example 1, except that the substitution rate of yttrium atoms with zirconium atoms was set to 10 mol%.

[0054] (Comparative Example 3) Water-repellent material 1 was obtained in the same manner as in Comparative Example 1, except that the substitution rate of yttrium atoms with zirconium atoms was set to 20 mol%.

[0055] (Comparative Example 4) A commercially available water-repellent film (Leafy LF-4362, Soken Chemical Co., Ltd.) was used as Comparative Example 4.

[0056] Incidentally, the ceramic mixture of zirconia and yttria used as a target for forming the adhesion portion 5 in Comparative Examples 1 to 3 is also used as a target for coating CBN tools, for example. CBN is an abbreviation for Cubic Boron Nitride, and is a sintered body made of boron and nitrogen. CBN tools have a hardness second only to diamond, high thermal conductivity, and are stable even at high temperatures, so they are used as cutting tools for high-hardness steel and the like. Although CBN tools have high wear resistance, further extension of their lifespan is desired. Therefore, by forming a coating of a mixture containing zirconia and yttria on the surface of a CBN tool, it is possible to impart further oxidation resistance to the CBN tool and improve its lifespan. For example, by forming the above coating on a φ1.0 radius end mill, tool life can be improved by 128% for materials with an HRC of 50 (e.g., SKD11), by 143% for materials with an HRC of 55 (e.g., STAVAX), and by 155% for materials with an HRC of 60 (e.g., ELMAX). The formation of the above coating on CBN tools may be carried out in the same manner as the adhesion formation process in Example 1, in which case the temperature during sputtering should be set to 200°C or higher.

[0057] For Examples 1-2 and Comparative Examples 1-4, a reciprocating friction test was conducted by rubbing the surface of the water-repellent material 1 back and forth to investigate its durability. The contact angle and sliding angle of water were measured before and after the reciprocating friction test. The reciprocating friction test was performed by applying a load of 500g to the surface of the water-repellent material 1 and moving a canvas cloth back and forth 1000 times at a speed of 50mm / s.

[0058] The contact angle was measured by dropping 2 μL of water droplets onto the surfaces of Examples 1-2 and Comparative Examples 1-4. The sliding angle was measured by dropping 20 μL of water droplets onto the surfaces of Examples 1-2 and Comparative Examples 1-4, and then moving the inclination angle of each water-repellent material 1 from 0° to 90° at a rate of 5° / s, and measuring the angle at which the droplets slid off. These measurement results are shown in Figures 7 and 8.

[0059] As shown in Figure 7, the contact angles of Examples 1-2 and Comparative Examples 1-4 before the reciprocating friction test all exceeded 140°, indicating that all exhibited high water repellency. However, while the contact angles of Examples 1-2 did not change significantly before and after the reciprocating friction test, the contact angles of Comparative Examples 1-4 changed significantly before and after the reciprocating friction test, with the contact angles after the test being about half the value before the test. Therefore, it can be seen that the water-repellent material 1 in this disclosure has high durability and its water-repellent performance is not lost due to friction.

[0060] As shown in Figure 8, the sliding angle in Examples 1 and 2 did not change significantly before and after the reciprocating friction test, showing a value of around 30° in Example 1 and around 25° in Example 2. In other words, it was found that even after the reciprocating friction test, the water-repellent material 1 in Examples 1 and 2 did not allow water droplets to adhere to its surface if it had an inclination of around 25 to 30°. On the other hand, the sliding angle in Comparative Examples 1 to 4 changed significantly before and after the reciprocating friction test. The sliding angle after the reciprocating friction test in Comparative Example 1 was about five times that of before the reciprocating friction test, and the sliding angle after the reciprocating friction test in Comparative Examples 2 and 3 was about twice that of before the reciprocating friction test. From this, it can be seen that the inclusion of silica in the adhesion portion 5 improves the wear resistance of the water-repellent material 1. In Comparative Example 4, the sliding angle, which was 1° before the reciprocating friction test, became 90° or more after the reciprocating friction test and did not slide. From these results, it can be seen that the water-repellent material 1 in this disclosure has high durability and that its water-repellent performance is not lost due to friction.

[0061] [Summary of the above embodiment] The following describes the outline of the water-repellent body 1, the water-repellent component 100, and the manufacturing method of the water-repellent body 1 as described in the above embodiment.

[0062] (1) The characteristic configuration of the water-repellent body (1) is that it comprises a base material (metal coating (3), resin film (7)) having an uneven structure (30, 70) and a coating (4) that covers the uneven structure (30, 70), wherein the coating (4) has a water-repellent portion (6) containing a fluorine compound and an adhesive portion (5) that adheres to the base material (metal coating (3), resin film (7)), and the adhesive portion (5) is a mixture containing silica and yttria.

[0063] According to this configuration, the uneven structure (30, 70) reduces the contact area between the substrate (metal coating (3), resin film (7)) and water droplets, and the water-repellent portion (6) containing a fluorine compound reduces the surface free energy of the uneven structure (30, 70), making it possible to impart high water repellency to the substrate (metal coating (3), resin film (7)). The water-repellent portion (6) is prone to peeling from the substrate (metal coating (3), resin film (7)) due to friction, etc., but the adhesive portion (5) that adheres to the substrate (metal coating (3), resin film (7)) contains silica and therefore readily bonds with the fluorine compound contained in the water-repellent portion (6). As a result, the adhesion between the water-repellent portion (6) and the adhesive portion (5) is improved, and peeling of the water-repellent portion (6) can be suppressed. In addition, since the adhesive portion (5) contains yttria, it has high hardness, making it possible to improve the durability of the uneven structure (30, 70). As a result, a highly durable water-repellent body (1) can be provided.

[0064] (2) In the water-repellent body (1) described above, the mixture contains some of the yttrium atoms Group 4 elements It may be substituted with an atom of the same type.

[0065] According to this configuration, some of the yttrium atoms form an oxide that is harder than yttria. Group 4 elements By substituting these atoms, the bonds between the atoms constituting the adhesion portion (5) are strengthened, increasing the hardness of the adhesion portion (5) and improving the durability of the uneven structure (30,70).

[0066] (3) In the water-repellent body (1) described in (2) above, Group 4 elements The atom may be a zirconium atom.

[0067] According to this configuration, by substituting some of the yttrium atoms with zirconium atoms that form zirconia, which is harder than yttria, the bonds between the atoms constituting the adhesion portion (5) are strengthened, increasing the hardness of the adhesion portion (5) and further improving the strength of the uneven structure (30,70).

[0068] (4) In the water-repellent body (1) described in any one of (1) to (3), the uneven structure (30, 70) may contain chromium.

[0069] According to this configuration, the inclusion of chromium in the uneven structure (30,70) improves the strength of the uneven structure (30,70). This makes it possible to enhance the durability of the water-repellent material (1).

[0070] (5) In the water-repellent body (1) described in any one of (1) to (3), the base material may be a resin film (7).

[0071] According to this configuration, a textured structure (70) is formed on the surface of the flexible resin film (7), which makes it possible to impart permeability and flexibility to the water-repellent body (1). This increases the selectivity of the appearance design of the water-repellent body (1). Furthermore, since the resin film (7) can be fixed to the surface of any object, it is possible to impart high water repellency to objects with large areas or objects with various shapes. As a result, high water repellency can be imparted to a variety of articles.

[0072] (6) In the water-repellent material (1) described in any one of (1) to (5), the fluorine compound may contain a difluoromethyl group.

[0073] In this configuration, the bond between the fluorine atom and the carbon atom in the difluoromethyl group is stable, so the forces acting between these molecules are weak, and the surface free energy of the water-repellent portion (6) is low. Therefore, the water-repellent portion (6) exhibits water repellency. In addition, a stable bond is easily formed between the fluorine atom contained in the water-repellent portion (6) and the silicon atom contained in the adhesion portion (5), so the water-repellent portion (6) adheres closely to the adhesion portion (5). This suppresses the peeling of the water-repellent portion (6).

[0074] (7) The characteristic configuration of the water-repellent component (100) is that it comprises a water-repellent body (1) described in any one of (1) to (5), and a coating target material (2) on which the water-repellent body (1) is formed.

[0075] According to this configuration, a highly durable water-repellent material (1) is formed on the surface of the material to be coated (2), so a water-repellent component (100) that does not easily lose its water-repellency can be obtained. As a result, even water-repellent components (100) that are easily touched by people's hands and are subject to friction can maintain their water-repellency for a long period of time.

[0076] (8) The characteristic of the method for producing the water-repellent body (1) is that it includes a step of forming an uneven structure (30) on the surface of a substrate (metal coating (3), resin film (7)), a step of forming an adhesive part (5) made of a mixture containing silica and yttria on the surface of the uneven structure (30), and a step of forming a water-repellent part (6) containing a fluorine compound on the surface of the adhesive part (5).

[0077] According to this configuration, by forming an uneven structure (30, 70) on the surface of the substrate (metal coating (3), resin film (7)) in the uneven structure formation process, it is possible to reduce the contact area between the substrate (metal coating (3), resin film (7)) and water droplets, etc. Furthermore, since the adhesive portion (5) formed in the adhesive portion formation process contains yttria, the durability of the uneven structure (30, 70) can be further improved by covering and protecting it with the adhesive portion (5). In addition, by forming a water-repellent portion (6) containing a fluorine compound on the surface of the adhesive portion (5) in the water-repellent portion formation process, it is possible to reduce the surface free energy of the substrate (metal coating (3), resin film (7)) and obtain high water repellency. Moreover, since the silicon contained in the adhesive portion (5) has a high affinity for the fluorine contained in the water-repellent portion (6), a stable bond is formed between them, and the adhesive portion (5) and the water-repellent portion (6) adhere to each other. Therefore, the water-repellent portion (6) is less likely to peel off from the substrate (metal coating (3), resin film (7)). This makes it possible to manufacture a highly durable water-repellent body (1).

[0078] (9) In the method for producing the water-repellent body (1) described in (8) above, the mixture contains a portion of the yttrium atoms Group 4 elements It may be substituted with an atom of the same type.

[0079] According to this configuration, some of the yttrium atoms form an oxide that is harder than yttria. Group 4 elements By substituting these atoms, the bonds between the atoms constituting the adhesion portion (5) are strengthened, increasing the hardness of the adhesion portion (5) and improving the durability of the uneven structure (30,70).

[0080] (10) In the method for producing the water-repellent body (1) described in (9) above, Group 4 elements The atom may be a zirconium atom.

[0081] According to this configuration, by substituting some of the yttrium atoms with zirconium atoms that form zirconia, which is harder than yttria, it is possible to strengthen the bonds between the atoms constituting the adhesion portion (5), increase the hardness of the adhesion portion (5), and improve the durability of the uneven structure (30,70).

[0082] In the method for producing the water-repellent body (1) described in any one of (11), (8), to (10), the uneven structure formation step may be carried out by sputtering.

[0083] With this configuration, the uneven structure formation process is carried out by sputtering, so the uneven structure (30) can be formed simultaneously with the formation of the substrate (metal coating (3)).

[0084] (12) In the method for producing the water-repellent body (1) described in (11) above, chromium may be used as the target in the step for forming the uneven structure.

[0085] According to this configuration, the inclusion of chromium in the uneven structure (30) makes it possible to improve the strength of the uneven structure (30).

[0086] In the method for producing a water-repellent body (1) described in any one of (13)(8) to (10), the uneven structure formation step may be performed by transferring the uneven structure (70) onto a flexible resin film (7).

[0087] According to this configuration, by pressing a mold (8) capable of forming a textured structure (70) onto a flexible resin film (7) and transferring the textured structure (70), the textured structure (70) can be efficiently formed even on resin films (7) with a large surface area. Furthermore, for example, by fixing the resin film (7) to the surface of an item to be given water repellency, water repellency can be imparted even to items on which a textured structure (70) cannot be directly formed. As a result, it becomes possible to impart water repellency to objects with large surfaces or objects with various shapes, thereby expanding the range of application of the water-repellent body (1). In addition, since the resin film (7) can be made permeable and flexible, it becomes possible to increase the selectivity of the appearance design of the water-repellent body (1).

[0088] In the method for producing the water-repellent material (1) described in any one of (14)(8) to (13), the fluorine compound may contain a difluoromethyl group.

[0089] In this configuration, the bond between the fluorine atom and the carbon atom in the difluoromethyl group is stable, so the forces acting between these molecules are weak, and the surface free energy of the water-repellent portion (6) is low. Therefore, the water-repellent portion (6) exhibits water repellency. In addition, a stable bond is easily formed between the fluorine atom contained in the water-repellent portion (6) and the silicon atom contained in the adhesion portion (5), so the water-repellent portion (6) adheres closely to the adhesion portion (5). This suppresses the peeling of the water-repellent portion (6).

[0090] (15) The water-repellent body (1) may be manufactured by the method for manufacturing the water-repellent body (1) described in any one of (8) to (14).

[0091] This configuration makes it possible to provide a highly durable water-repellent body (1) that has high water repellency and can suppress the peeling of the water-repellent portion (6). [Industrial applicability]

[0092] The present invention can be used for water-repellent materials, water-repellent components equipped with water-repellent materials, and methods for manufacturing water-repellent materials. [Explanation of Symbols]

[0093] 1: Water-repellent coating 2: Material to be coated 3: Metal coating (base material) 4:Coating 5: Contact area 6: Water-repellent part 7: Resin film (substrate) 30: Uneven structure 70: Uneven structure 100: Water-repellent parts

Claims

1. A substrate having an uneven structure in which the height difference between the convex portion and the concave portion is 10 nm to 5 μm, The coating comprises a film covering the aforementioned uneven structure, The coating has a water-repellent portion containing a fluorine compound and an adhesive portion that adheres to the substrate. The aforementioned adhering portion is a water-repellent material which is a mixture containing silica and yttria.

2. The water-repellent material according to claim 1, wherein the mixture has some of its yttrium atoms replaced by atoms of a group 4 element.

3. The water-repellent material according to claim 2, wherein the atom of the group 4 element is a zirconium atom.

4. The water-repellent body according to claim 1, wherein the uneven structure is formed of metal.

5. The water-repellent body according to claim 4, wherein the aforementioned uneven structure contains chromium.

6. The water-repellent body according to claim 1, wherein the substrate is a flexible resin film.

7. The water-repellent material according to claim 1, comprising a difluoromethyl group as the fluorine compound.

8. A water-repellent body according to any one of claims 1 to 7, A water-repellent component comprising a material to be coated, on which the water-repellent material is formed on the surface.

9. A process for forming an uneven surface on the substrate, in which the difference in height between the convex and concave portions is 10 nm to 5 μm, A step of forming an adhesion portion, in which an adhesion portion made of a mixture containing silica and yttria is formed on the surface of the aforementioned uneven structure, A method for producing a water-repellent body, comprising a step of forming a water-repellent portion on the surface of the adhering portion, which contains a fluorine compound.

10. The method for producing a water-repellent material according to claim 9, wherein the mixture has some of its yttrium atoms replaced by atoms of a group 4 element.

11. The method for producing a water-repellent material according to claim 10, wherein the atom of the group 4 element is a zirconium atom.

12. The method for producing a water-repellent material according to claim 9, wherein the step of forming the uneven structure is carried out by sputtering.

13. The method for producing a water-repellent material according to claim 12, wherein the step of forming the uneven structure is performed using chromium as the target.

14. The method for producing a water-repellent material according to claim 9, wherein the step of forming the uneven structure is carried out by transferring the uneven structure onto a flexible resin film.

15. The method for producing a water-repellent material according to claim 9, wherein the fluorine compound comprises a difluoromethyl group.

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