Water-repellent object, water-repellent component, and method for producing water-repellent object

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 the 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 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 likely to be lost.

[0006] Therefore, a highly durable water-repellent body having high water repellency and capable of suppressing the peeling of the coating (water-repellent part) is desired.

Means for Solving the Problems

[0007] One embodiment of the water-repellent body according to the present invention includes a base material having an uneven structure and a film covering the uneven structure. The film has a water-repellent part containing a fluorine compound and an adhesion part that adheres to the base material. The adhesion part is a mixture containing silica and yttria.

[0008] One embodiment of the water-repellent component according to the present invention includes a water-repellent body and a film target material on the surface of which the water-repellent body is formed.

[0009] One embodiment of the method for manufacturing a water-repellent body according to the present invention includes an uneven structure forming step of forming an uneven structure on the surface of a base material, an adhesion part forming step of forming an adhesion part made of a mixture containing silica and yttria on the surface of the uneven structure, and a water-repellent part forming step of forming a water-repellent part containing a fluorine compound on the surface of the adhesion part.

Advantages of the Invention

[0010] According to the embodiment of the present invention, it is possible to provide a highly durable water-repellent body having high water repellency and capable of suppressing peeling of the water-repellent part, a water-repellent component including the water-repellent body, and a method for manufacturing the water-repellent body.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the water-repellent body according to the present invention will be described with reference to the drawings. Note that the embodiments described below are examples for explaining the present invention, and the present invention is not limited only to these embodiments. Therefore, the present invention can be implemented in various forms without departing from its gist.

[0013] 〔First Embodiment〕 FIG. 1 is a longitudinal sectional view of a water-repellent component 100 according to the present embodiment. The water-repellent component 100 includes a water-repellent body 1 and a material to be coated 2. The water-repellent component 100 is a component of various products that requires water repellency, although it is not particularly limited. The material to be coated 2 is a metal such as aluminum or iron, glass, ceramics, or the like. The material to be coated 2 in FIG. 1 is a single layer, but it is not limited thereto and may be a laminate of a plurality of layers. In that case, each layer may be the same or different. The material to be coated 2 may be, for example, an automobile body or a door knob portion. A water-repellent body 1 is formed on the surface of the material to be coated 2.

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

[0015] FIG. 2 is an SEM (Scanning Electron Microscope) image showing the surface of the uneven structure 30, and FIG. 3 is an SEM image showing the longitudinal section of the metal film 3. As shown in FIGS. 2 and 3, the metal film 3 is a columnar crystal with a sharp tip at the front end, and this front end portion is defined as the uneven structure 30. The metal film 3 in FIGS. 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 is formed 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 being added to silica. Therefore, compared with the hydrophilic silica particles usually used as an adhesive, the adhesion part 5 has high hardness and high durability. Accordingly, by covering the surface of the uneven structure 30 with the adhesion part 5, it is possible to protect the uneven structure 30 with the adhesion part 5. Thereby, 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. Note that 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] A part of the yttrium atoms contained in the adhesion part 5 may be substituted with atoms of a Group 4A element. The Group 4A element is not particularly limited. For example, it may be at least one selected from the group consisting of titanium, zirconium, and hafnium, and particularly preferably zirconium. These elements may be used singly or in combination. When a part of the yttrium atoms is substituted with these atoms, the bond of the atoms in the adhesion part 5 becomes strong. Therefore, it is considered that the hardness of the adhesion part 5 is higher than that in the case where a part of the yttrium atoms is not substituted. Thereby, it is possible to impart scratch resistance and the like to the uneven structure 30 and improve the durability.

[0021] In the adhesion part 5, the substitution rate (content rate of the atoms of the Group 4A element) at which the yttrium atoms are substituted with the atoms of the Group 4A element is not particularly limited as long as it exceeds 0, and the upper limit value may be, for example, 20 mol%, 15 mol%, 10 mol%, or 5 mol%.

[0022] Further, some of the oxygen atoms in yttria may be substituted with nitrogen atoms. Since the bondability between the nitrogen atom and the yttrium atom is higher than that between the oxygen atom and the yttrium atom, the strength of the adhesion part 5 is improved by substituting some of the oxygen atoms in yttria with nitrogen atoms. Thereby, the strength of the water repellent body 1 including the adhesion part 5 is also improved.

[0023] In the adhesion part 5, the substitution rate (nitrogen atom content rate) at which some of the oxygen atoms in yttria are substituted with nitrogen atoms is not particularly limited as long as it exceeds 0, and it may be 1 atomic%, and the upper limit value may be, for example, 10 atomic%, 5 atomic%, 3 atomic%, or 2 atomic%.

[0024] A water repellent part 6 is formed on the surface of the adhesion part 5. The water repellent part 6 contains a fluorine compound. The fluorine compound preferably has a difluoromethyl group and may contain silicon, oxygen, or the like. As described above, the water repellent part 6 adheres to the adhesion part 5 by generating a stable bond between the silicon atom of the adhesion part 5 and the fluorine atom of the water repellent part 6. Further, since the bond between the fluorine atom and the carbon atom contained in the water repellent part 6 is stable, the force acting between these molecules is weak and the surface free energy of the water repellent part 6 is low. Therefore, the water repellent part 6 exhibits water repellency. The water repellent part 6 preferably has a thickness of 5 nm to 90 nm and is preferably formed uniformly on the surface of the adhesion part 5 (or the uneven structure 30).

[0025] Here, when water droplets adhere to the surface of the water-repellent body 1, the contact area between the water-repellent body 1 and the water droplets is the contact area between the tips of the uneven structure 30 and the water droplets. Therefore, by having the uneven structure 30, the water-repellent body 1 can reduce the contact area between the water droplets and the water-repellent body 1. And, by forming the water-repellent part 6 having water-repellency on the surface of the uneven structure 30, high water-repellency is imparted to the water-repellent body 1. That is, the high water-repellency of the water-repellent body 1 in the present embodiment is realized by the combination of the uneven structure 30 and the water-repellent part 6. Since the water-repellent body 1 has the effect of suppressing the wet spread of water on its surface, for example, it can be applied to the surface of a glass lens, the surface of a human sensor mounted on an automobile, or the like.

[0026] 〔Method for manufacturing water-repellent body〕 Subsequently, with reference to FIG. 4, a method for manufacturing the water-repellent component 100 and the water-repellent body 1 will be described. First, an uneven structure forming step of forming a metal film 3 and an uneven structure 30 on the surface of the film target material 2 is performed. The uneven structure forming step is performed by a sputtering method, and titanium, chromium, or the like can be used as the target. If the gas pressure of the sputtering gas in the uneven structure forming step is too low, a smooth metal film 3 is formed on the surface of the film target material 2, and thus the uneven structure 30 cannot be obtained. Therefore, in the uneven structure forming step, it is preferable to form the uneven structure 30 under medium to high pressure (for example, 1 Pa or more). Thus, by forming the uneven structure 30 using the sputtering method, the strength of the uneven structure 30 can be increased.

[0027] In the uneven structure forming step, the method of performing sputtering other than the above-described method is not particularly limited, and for example, it may be the same as or similar to a general sputtering method.

[0028] Next, a contact portion forming step of forming a contact portion 5 on the surface of the uneven structure 30 is performed. The contact portion forming step is not particularly limited. For example, it can be performed by a vacuum evaporation method, a sputtering method, an ion plating method, an ion beam evaporation method classified as physical vapor deposition, or an atomic layer deposition method or a plasma CVD method classified as chemical vapor deposition. The evaporation method tends to form a film with a high film formation rate but a low hardness (soft). The sputtering method tends to form a film with a low film formation rate but a high hardness (hard). In the contact portion forming step in the present embodiment, from the viewpoint of improving the strength of the uneven structure 30, it is preferable to use the sputtering method. Further, according to the sputtering method, the contact portion 5 can be uniformly formed on the surface of the uneven structure 30.

[0029] In the contact portion forming step, a mixture of silica and yttria can be used as a target. Thereby, since the contact portion 5 can be uniformly formed on the surface of the uneven structure 30, it is possible to bring the water repellent portion 6 into close contact with the uneven structure 30. Note that a part of the yttrium atoms in the mixture may be substituted with atoms of Group 4A elements such as zirconium atoms.

[0030] Further, regarding the yttria contained in the contact portion 5, in order to further substitute a part of the oxygen atoms with nitrogen atoms, for example, film formation may be performed by a method of sputtering in an atmosphere in which nitrogen is added to argon (reactive sputtering method).

[0031] In the contact portion forming step, the method of performing sputtering is not particularly limited. For example, it may be the same as or similar to a general sputtering method. From the viewpoint of manufacturing efficiency, it is preferable that the film formation rate by the sputtering method is not too slow, and from the viewpoint of the hardness of the contact portion 5, it is preferable that the film formation rate by the sputtering method is not too fast.

[0032] Finally, a water repellent portion forming step of forming a water repellent portion 6 on the surface of the contact portion 5 is performed. The water repellent portion forming step is not particularly limited. For example, it can be performed by a plasma gas treatment method. As the plasma gas treatment method, atmospheric pressure plasma treatment, corona treatment, or the like can be used.

[0033] In the water-repellent part forming process, fluorine compounds to be used include, for example, perfluorocarbons such as carbon tetrafluoride and perfluorocyclobutane, hydrofluorocarbons such as trifluoromethane and difluoromethane, sulfur hexafluoride, nitrogen trifluoride, and the like. When these gases are made into plasma, fluorine-based active species are formed, and the surface free energy of the water-repellent body 1 is reduced by the film derived from the fluorine-based active species held in the adhesion part 5. Thereby, it becomes possible to impart high water repellency to the water-repellent body 1.

[0034] In addition, in the water-repellent part forming process, the method of performing the plasma gas treatment is not particularly limited, and for example, it may be the same as or similar to a general plasma gas treatment. Further, the uneven structure forming process, the adhesion part forming process, and the water-repellent part forming 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 FIG. 5. The resin film 7 (an example of a base material) provided with the uneven structure 70 is a flexible resin film. As shown in FIG. 5, the uneven structure 70 in the present embodiment is continuously formed on the surface of the resin film 7. The adhesion part 5 and the water-repellent part 6 are formed in this order on the surface of the uneven structure 70. Since the other configurations are the same as those in the first embodiment, the description of the same configurations will be omitted.

[0036] The uneven structure 70 formed by the resin film 7 is inferior in strength and is liable to collapse as compared with the uneven structure 30 formed of metal or the like in the first embodiment. Therefore, in the present embodiment, the strength of the uneven structure 70 is maintained by the adhesion part 5 covering the uneven structure 70.

[0037] The resin film 7 is not particularly limited as long as it is a flexible resin. For example, a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like can be used. Examples of the thermoplastic resin include polyester resins such as polyethersulfone-based resins, polycarbonate-based resins, acrylic resins, polyethylene terephthalate-based resins, and polyethylene naphthalate-based resins; unsaturated polyester-based resins; polyolefin-based resins; cycloolefin-based resins such as norbornene-based resins; polyimide-based resins; polyamide-based resins; polyimide amide-based resins; polyarylate-based resins; polysulfone-based resins; polyetherimide-based resins, and the like. Examples of the thermosetting resin include phenolic resins, epoxy resins, and urethane resins. Examples of the photocurable resin include acrylic resins and epoxy resins. From the viewpoint of the moldability of the concavo-convex structure 70, it is preferable to use a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like as the resin film 7. Further, according to the performance of the water repellent 1, a resin having heat resistance may be selected.

[0038] The thickness of the resin film 7 is, for example, 100 nm to 1 mm. If such a thin resin film 7 is adhered to the surface of an article or the like (coating target material) to which water repellency is to be imparted, it is possible to impart water repellency to a coating target material having a complex shape. Since high water repellency can be imparted to an object having a large area, it is possible to impart water repellency to various articles. Further, by continuously connecting a plurality of resin films 7, high water repellency can be imparted to the roll-shaped film itself.

[0039] The resin film 7 may or may not be colored. By coloring the resin film 7, it is possible to color the water repellent 1 and enhance the selectivity of the appearance design of the water repellent 1. Further, the resin film 7 may have permeability. By having permeability, even if the resin film 7 is fixed to the surface of the coating target material, the color development or the like of the coating target material will not be inhibited. Therefore, the water repellent 1 can be easily applied to an existing product or the like, and it is possible to impart water repellency to various articles.

[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. For example, an acrylic resin or a polyester resin may be used.

[0041] [Method for manufacturing a water-repellent] Subsequently, the manufacturing method of the water-repellent 1 will be described with reference to FIG. 6. First, an uneven structure forming step of forming an uneven structure 70 on the surface of the resin film 7 is performed. The uneven structure forming step is performed by pressing a molding die 8 against the resin film 7 to transfer the uneven structure 70.

[0042] The molding die 8 is, for example, a mold, and is formed so as to be able to transfer the uneven structure 70. The molding die 8 is processed by etching, laser, electroforming, or the like 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 molding die 8 using electroforming that can form such an uneven structure 70 with high precision. For creating the molding die 8, the uneven structure 30 formed by the sputtering method in the first embodiment may be used.

[0043] The transfer can be performed by a thermal imprint method, a UV imprint method, a nano casting method, a reverse imprint method, a roll-to-roll method, or the like. The thermal imprint method has a disadvantage in production efficiency due to the accompanying thermal cycle, but can process various materials. Also, the UV imprint method has an advantage that it can be efficiently transferred in a short time. In the present embodiment, any method can be used.

[0044] When producing the resin film 7 using a thermoplastic resin, the thermoplastic resin heated to a softened state is clamped by a mold 8 (the mold 8 is pressed against the thermoplastic resin). Thereafter, the thermoplastic resin is cooled and the mold is opened to obtain a resin film 7 having the concavo-convex structure 70. When producing the resin film 7 using a thermosetting resin, it is advisable to heat the liquid thermosetting resin after clamping it with the mold 8. After the thermosetting resin is cured by heating, the mold is opened to obtain a resin film 7 having the concavo-convex structure 70. When producing the resin film 7 using a photocurable resin, a liquid thermosetting resin is applied to the surface of the material to be coated, and in a state where clamping is performed with a transparent mold 8, light is irradiated to cure the photocurable resin. Thereafter, the mold is opened to obtain the resin film 7. Also, the liquid photocurable resin may be irradiated with light, and after clamping the photocurable resin in a state where it is somewhat cured with an opaque mold 8, the mold is opened, and further light is irradiated to completely cure it.

[0045] Subsequently, an adhesion part forming step of forming an adhesion part 5 on the surface of the concavo-convex structure 70 is performed, and thereafter, a water repellent part forming step of forming a water repellent part 6 on the surface of the adhesion part 5 is performed. Since the adhesion part forming step and the water repellent part forming step are the same as those in the first embodiment, detailed description thereof is omitted.

[0046] The water repellent body 1 having the adhesion part 5 and the water repellent part 6 formed on the resin film 7 may be fixed to the surface of the material to be coated. The fixing may be performed by applying an adhesive of an acrylic resin or a polyester resin, for example, to the surface of the material to be coated and fixing the water repellent body 1 to the surface thereof. Thereby, since the adhesive adheres the material to be coated and the water repellent body 1, the water repellent body 1 is fixed to the surface of the material to be coated, and the high water repellency of the water repellent body 1 is imparted to the material to be coated. An adhesive may be applied to the surface of the water repellent body 1 that contacts the material to be coated. When clamping is performed in a state where a liquid thermosetting resin or a photocurable resin is applied to the material to be coated and the resin is cured by heating or light irradiation, since the resin film 7 is fixed to the surface of the material to be coated as the resin cures, fixing with an adhesive or the like is unnecessary.

[0047] 〔Example〕 Hereinafter, examples of the present disclosure will be described. However, the present disclosure is not limited to the following examples.

[0048] (Example 1) Example 1 was created using the method for manufacturing a water-repellent body of the present disclosure. First, as the uneven structure forming step, a metal film 3 having an uneven structure 30 was formed on the surface of the film target material 2 by sputtering using a sputtering apparatus (E-200S, Canon Anelva Corporation). In the uneven structure forming step, a DC power source was used and the input power was set to 150 W. 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 to high pressure, and the substrate was heated in the range of room temperature to 200 °C to obtain the metal film 3 and the uneven structure 30. The film thickness of the obtained metal film 3 was 2.5 μm.

[0049] Subsequently, as the adhesion part forming step, an adhesion part 5 was formed on the surface of the uneven structure 30 by sputtering using a sputtering apparatus (E-200S, Canon Anelva Corporation). In the adhesion part forming step, a high-frequency power source was used and the input power was set to 75 W. A ceramic (sintered density: 65% to 98%) which is a mixture of silica and yttria was used as the target for forming the adhesion part 5. The ceramic was obtained by hot pressing using a multi-purpose high-temperature furnace (Himalti 5000, Fuji Denpa Kogyo Co., Ltd.). Argon was used as the sputtering gas, and the adhesion part 5 was obtained by film formation at room temperature under low pressure. The film thickness of the obtained adhesion part 5 was 30 nm.

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

[0051] (Example 2) In the adhesion part forming step, a water repellent 1 was obtained in the same manner as in Example 1, except that ceramics, which is a mixture of silica, zirconia, and yttria, was used as a target for forming the adhesion part 5, and argon and nitrogen were used as sputtering gases. In Example 2, the substitution rate at which yttrium atoms were substituted for zirconium atoms was set to 5 to 20 mol%. Also, a part of the oxygen atoms in yttria was substituted with nitrogen atoms. The ceramics (sintered density: 65% to 98%) used in the preparation of Example 2 was prepared in the same manner as in Example 1.

[0052] (Comparative Example 1) A water repellent 1 was obtained in the same manner as in Example 2, except that ceramics, which is a mixture of zirconia and yttria, was used as a target for forming the adhesion part 5. In Comparative Example 1, the substitution rate at which yttrium atoms were substituted for zirconium atoms was set to 5 mol%. Also, a part of the oxygen atoms in yttria was substituted with nitrogen atoms. The ceramics (sintered density: 65% to 98%) used in the preparation of Comparative Example 1 was prepared in the same manner as in Example 1.

[0053] (Comparative Example 2) A water repellent 1 was obtained in the same manner as in Comparative Example 1, except that the substitution rate at which yttrium atoms were substituted for zirconium atoms was set to 10 mol%.

[0054] (Comparative Example 3) A water repellent 1 was obtained in the same manner as in Comparative Example 1, except that the substitution rate at which yttrium atoms were substituted for zirconium atoms was set to 20 mol%.

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

[0056] Incidentally, the ceramics, which is a mixture of zirconia and yttria used as a target for forming the adhesion part 5 in Comparative Examples 1 to 3, is also used, for example, as a target for coating a CBN tool. CBN is an abbreviation for Cubic Boron Nitride, and is a sintered body made of boron and nitrogen. Since the CBN tool has hardness second only to diamond, high thermal conductivity, and is stable even at high temperatures, it is used as a cutting tool for high-hardness steel and the like. Although the CBN tool has high wear resistance, further extension of its service life is desired. Therefore, by forming a mixture containing zirconia and yttria as a coating on the surface of the CBN tool, further oxidation resistance can be imparted to the CBN tool, and the service life of the CBN tool can be improved. For example, by forming the above coating on a φ1.0 radius end mill, the tool life for a material with HRC50 (for example, SKD11) can be improved by 128%, for a material with HRC55 (for example, STAVAX) by 143%, and for a material with HRC60 (for example, ELMAX) by 155%. Note that the formation of the above coating on the CBN tool may be performed in the same manner as the adhesion part forming step in Example 1. In this case, the temperature during sputtering may be set to 200°C or higher.

[0057] For Examples 1 to 2 and Comparative Examples 1 to 4, in order to investigate their respective durability, a reciprocating friction test was performed in which the surface of the water-repellent body 1 was reciprocally rubbed, and the contact angle and sliding angle of water before and after the reciprocating friction test were measured. The reciprocating friction test was performed by reciprocating the canvas cloth 1000 times at a speed of 50 mm / s while applying a load of 500 g to the surface of the water-repellent body 1.

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

[0059] As shown in Fig. 7, since the contact angles of Examples 1 to 2 and Comparative Examples 1 to 4 before the reciprocating friction test all exceed 140°, it can be seen that they all exhibit high water repellency. However, while the contact angles in Examples 1 to 2 did not change significantly before and after the reciprocating friction test, the contact angles in Comparative Examples 1 to 4 changed significantly before and after the reciprocating friction test, and the contact angles after the reciprocating friction test showed values about half of those before the reciprocating friction test. Therefore, it can be seen that the water-repellent body 1 in the present disclosure has high durability and the water-repellent performance is not lost due to friction.

[0060] As shown in Fig. 8, the sliding angles in Examples 1 to 2 did not change significantly before and after the reciprocating friction test. In Example 1, the value was around 30°, and in Example 2, the value was around 25°. That is, it was found that as long as the water-repellent body 1 in Examples 1 to 2 has a slope of around 25 to 30° even after the reciprocating friction test, water droplets do not adhere to its surface. On the other hand, the sliding angles 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 5 times that before the reciprocating friction test, and the sliding angles after the reciprocating friction test in Comparative Examples 2 to 3 were about 2 times the values before the reciprocating friction test. From this, it can be seen that the wear resistance of the water-repellent body 1 is improved by the adhesion part 5 containing silica. 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 the above results, it can be seen that the water-repellent body 1 in the present disclosure has high durability and the water-repellent performance is not lost due to friction.

[0061] 〔Outline of the above embodiment〕 Hereinafter, an outline of the water-repellent body 1, the water-repellent component 100, and the manufacturing method of the water-repellent body 1 described in the above embodiment will be described.

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

[0063] According to this configuration, the uneven structure (30, 70) reduces the contact area between the base material (metal film (3), resin film (7)) and water droplets, etc., and the water-repellent part (6) containing a fluorine compound can reduce the surface free energy of the uneven structure (30, 70). Therefore, it is possible to impart high water repellency to the base material (metal film (3), resin film (7)). The water-repellent part (6) is likely to peel off from the base material (metal film (3), resin film (7)) due to friction, etc. Since the adhesion part (5) that adheres to the base material (metal film (3), resin film (7)) contains silica, it is likely to bond with the fluorine compound contained in the water-repellent part (6). As a result, the adhesiveness between the water-repellent part (6) and the adhesion part (5) is improved, so that peeling of the water-repellent part (6) can be suppressed. In addition, since the adhesion part (5) contains yttria, it has high hardness, and it is possible to improve the durability of the uneven structure (30, 70). Thereby, it is possible to provide a water-repellent body (1) with high durability.

[0064] (2) In the water-repellent body (1) described in (1) above, in the mixture, a part of the yttrium atoms may be substituted with atoms of Group 4A elements.

[0065] According to this configuration, by substituting a part of the yttrium atoms with atoms of Group 4A elements that form oxides harder than yttria, the bonds of the atoms constituting the adhesion part (5) are strengthened, the hardness of the adhesion part (5) is increased, and the durability of the uneven structure (30, 70) can be improved.

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

[0067] According to this configuration, by substituting part of the yttrium atoms with zirconium atoms that form zirconia which is harder than yttria, the bond of the atoms constituting the adhesion part (5) is strengthened, the hardness of the adhesion part (5) is increased, and the strength of the uneven structure (30, 70) can be further improved.

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

[0069] According to this configuration, since the uneven structure (30, 70) contains chromium, the strength of the uneven structure (30, 70) can be improved. Thereby, it becomes possible to enhance the durability of the water-repellent body (1).

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

[0071] According to this configuration, by forming the uneven structure (70) on the surface of the flexible resin film (7), it becomes possible to impart permeability and flexibility to the water-repellent body (1). Thereby, the selectivity of the appearance design of the water-repellent body (1) can be enhanced. Further, since the resin film (7) can be fixed to the surface of any object, it becomes possible to impart high water repellency to an object having a large area or an object having various shapes. As a result, high water repellency can be imparted to various articles.

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

[0073] According to this configuration, since the bond between the fluorine atom and the carbon atom in the difluoromethyl group is stable, the force acting between these molecules is weak and the surface free energy of the water-repellent part (6) is low. Therefore, the water-repellent part (6) exhibits water repellency. In addition, since a stable bond is likely to occur between the fluorine atom contained in the water-repellent part (6) and the silicon atom contained in the adhesion part (5), the water-repellent part (6) adheres to the adhesion part (5). Thereby, peeling of the water-repellent part (6) can be suppressed.

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

[0075] According to this configuration, since a highly durable water-repellent body (1) is formed on the surface of the film target material (2), a water-repellent component (100) that is less likely to lose its water repellency can be obtained. Thereby, even for a water-repellent component (100) that is easily touched by a person's hand or the like and is easily subjected to friction, long-term maintenance of water repellency becomes possible.

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

[0077] According to this configuration, by forming the concavo-convex structure (30, 70) on the surface of the base material (metal film (3), resin film (7)) in the concavo-convex structure forming step, it is possible to reduce the contact area between the base material (metal film (3), resin film (7)) and water droplets or the like. Further, since the adhesion part (5) formed in the adhesion part forming step contains yttria, by covering and protecting the concavo-convex structure (30, 70) with the adhesion part (5), it is also possible to further improve the durability of the concavo-convex structure (30, 70). Furthermore, in the water-repellent part forming step, by forming the water-repellent part (6) containing a fluorine compound on the surface of the adhesion part (5), it is possible to reduce the surface free energy of the base material (metal film (3), resin film (7)) and obtain high water repellency. Also, since silicon contained in the adhesion part (5) has a high affinity with fluorine contained in the water-repellent part (6), a stable bond is formed between them and the adhesion part (5) and the water-repellent part (6) adhere to each other. For this reason, the water-repellent part (6) is difficult to peel off from the base material (metal film (3), resin film (7)). Thereby, it is possible to manufacture a highly durable water-repellent body (1).

[0078] (9) In the method for manufacturing the water-repellent body (1) according to (8) above, in the mixture, a part of the yttrium atoms may be substituted with atoms of a Group 4A element.

[0079] According to this configuration, by substituting a part of the yttrium atoms with atoms of a Group 4A element that forms an oxide harder than yttria, the bonds of the atoms constituting the adhesion part (5) are strengthened, the hardness of the adhesion part (5) is increased, and the durability of the concavo-convex structure (30, 70) can be improved.

[0080] (10) In the method for manufacturing the water-repellent body (1) according to (9) above, the atoms of the Group 4A element may be zirconium atoms.

[0081] According to this configuration, by substituting a part of the yttrium atoms with zirconium atoms that form zirconia harder than yttria, the bonds of the atoms constituting the adhesion part (5) are strengthened, the hardness of the adhesion part (5) is increased, and the durability of the concavo-convex structure (30, 70) can be improved.

[0082] (11) In the method for manufacturing the water-repellent body (1) according to any one of (8) to (10), the uneven structure forming step may be performed by a sputtering method.

[0083] According to this configuration, since the uneven structure forming step is performed by a sputtering method, the uneven structure (30) can be formed simultaneously with the formation of the base material (metal film (3)).

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

[0085] According to this configuration, since the uneven structure (30) contains chromium, it is possible to improve the strength of the uneven structure (30).

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

[0087] According to this configuration, by pressing the molding die (8) capable of forming the uneven structure (70) against the flexible resin film 7 and transferring the uneven structure (70), the uneven structure (70) can be efficiently formed even on a resin film (7) having a large surface area. Further, for example, if the resin film (7) is fixed to the surface of an article or the like to which water repellency is to be imparted, water repellency can be imparted even to an article on which the uneven structure (70) cannot be directly formed. For this reason, it is possible to impart water repellency to an object having a large area or an object having various shapes, and the application range of the water-repellent body (1) can be expanded. In addition, since the resin film (7) can have permeability and flexibility, it is possible to enhance the selectivity of the appearance design of the water-repellent body (1).

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

[0089] According to this configuration, since the bonds between fluorine atoms and carbon atoms in the difluoromethyl group are stable, the forces acting between these molecules are weak, and the surface free energy of the water-repellent part (6) is low. Therefore, the water-repellent part (6) exhibits water repellency. Also, since a stable bond is likely to occur between the fluorine atoms contained in the water-repellent part (6) and the silicon atoms contained in the adhesion part (5), the water-repellent part (6) adheres to the adhesion part (5). Thereby, peeling of the water-repellent part (6) can be suppressed.

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

[0091] According to this configuration, it is possible to provide a highly durable water-repellent body (1) that has high water repellency and can suppress peeling of the water-repellent part (6).

Industrial Applicability

[0092] The present invention can be used for a water-repellent body, a water-repellent component including the water-repellent body, and a method for manufacturing the water-repellent body.

Explanation of Reference Numerals

[0093] 1: Water-repellent body 2: Coating target material 3: Metal coating (base material) 4: Coating 5: Adhesion part 6: Water-repellent part 7: Resin film (base material) 30: Concavo-convex structure 70: Concavo-convex structure 100: Water-repellent component

Claims

1. A base material having a concavo-convex structure, and a coating covering the concavo-convex structure, wherein the coating has a water-repellent part containing a fluorine compound and an adhesion part that adheres to the base material, and the adhesion part is a water-repellent body that is a mixture containing silica and yttria.

2. The water-repellent body according to claim 1, wherein a part of the yttrium atoms in the mixture is substituted with atoms of a Group 4A element.

3. The water-repellent body according to claim 2, wherein the atoms of the Group 4A element are zirconium atoms.

4. The water-repellent body according to any one of claims 1 to 3, wherein the concavo-convex structure contains chromium.

5. The water-repellent body according to any one of claims 1 to 3, wherein the base material is a flexible resin film.

6. The water-repellent body according to any one of claims 1 to 5, wherein the fluorine compound contains a difluoromethyl group.

7. A water-repellent component comprising the water-repellent body according to any one of claims 1 to 6 and a film target material on which the water-repellent body is formed on the surface.

8. A concavo-convex structure forming step of forming a concavo-convex structure on the surface of a base material, an adhesion part forming step of forming an adhesion part made of a mixture containing silica and yttria on the surface of the concavo-convex structure, and a water-repellent part forming step of forming a water-repellent part containing a fluorine compound on the surface of the adhesion part, the method for manufacturing a water-repellent body comprising these steps.

9. The method for manufacturing a water-repellent body according to claim 8, wherein a part of the yttrium atoms in the mixture is substituted with atoms of a Group 4A element.

10. The method for manufacturing a water-repellent body according to claim 9, wherein the atoms of the Group 4A element are zirconium atoms.

11. The method for manufacturing a water-repellent body according to any one of claims 8 to 10, wherein the concavo-convex structure forming step is performed by a sputtering method.

12. The method for manufacturing a water-repellent body according to claim 11, wherein chromium is used as a target in the concavo-convex structure forming step.

13. The method for manufacturing a water-repellent body according to any one of claims 8 to 10, wherein the concavo-convex structure forming step is performed by transferring the concavo-convex structure onto a flexible resin film.

14. The method for manufacturing a water-repellent body according to any one of claims 8 to 13, wherein the fluorine compound contains a difluoromethyl group.

15. A water-repellent body manufactured by the manufacturing method according to any one of claims 8 to 14.

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