Water-repellent member

Abstract

Provided is a water-repellent member that can achieve both high water repellency and high productivity.　This water-repellent member has protrusions and recesses on at least a portion of a surface, and when the cut-off value of a high-pass filter λc is set to 25 μm and the cut-off value of a low-pass filter λs is set to 0.25 μm in a 96 μm x 72 μm region of the surface having the protrusions and recesses, the arithmetic mean height Sa is 15 nm-200 nm, and the ratio Sa / RSm of the arithmetic mean height Sa to the mean length RSm of the roughness profile elements exceeds 10.0×10-3 but is at most 30.0×10-3.

Description

Water-repellent material

[0001] The present invention relates to a water-repellent member, which is a member having water-repellent properties.

[0002] The visibility of window components, camera / sensor lenses, cover components, and mirror components is impaired by the adhesion of rainwater, etc. This significantly reduces the functionality of these components. However, by using water-repellent materials on components where visibility is essential, it is possible to prevent water droplets from adhering to the surface of these components. This ensures the visibility of these components even in rainy weather. Therefore, the demand for components with low wettability and suitable for use as transparent or reflective components has been increasing in recent years.

[0003] Typically, coating treatments using fluororesin or silicone resin are used to impart water repellency to the surface of a component. However, on smooth surfaces, it is not possible to achieve high water repellency with a water contact angle exceeding 120°. Therefore, in order to obtain higher water repellency, attempts have been made to combine uneven structures with coating treatments.

[0004] For example, Patent Document 1 below discloses a method for producing a functional film with high water repellency by etching an inorganic layer multiple times to form a surface with a fine uneven structure on the inorganic layer, and then applying a water-repellent film to the surface.

[0005] Japanese Patent Publication No. 2024-085086

[0006] However, in order to obtain high water repellency such as the functional film described in Patent Document 1, it is necessary to form a complex micro-textured structure. The manufacturing method described in Patent Document 1 involves a complex process, such as repeating etching multiple times using a vacuum process. As a result, manufacturing costs are high and it becomes difficult to produce large-area products.

[0007] The object of the present invention is to provide a water-repellent member that can achieve high water repellency and high productivity.

[0008] Each embodiment of the water-repellent member that solves the above problem will be described.

[0009] A water-repellent member according to Embodiment 1 of the present invention is a water-repellent member having irregularities on at least a part of its surface, wherein in a 96 μm × 72 μm region on the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the ratio Sa / RSm of the arithmetic mean height Sa to the average length RSm of the roughness curve elements is 10.0 × 10 －３ It exceeds 30.0 x 10 －３ It is characterized by the following:

[0010] A water-repellent member according to embodiment 2 of the present invention is a water-repellent member having irregularities on at least a part of its surface, characterized in that, in a 96 μm × 72 μm region on the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the root mean square gradient Sdq of the contour curved surface is 0.15 or more and 0.70 or less.

[0011] In the water-repellent member of embodiment 3, in embodiment 1 or embodiment 2, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, it is preferable that the average length RSm of the roughness curve elements of the uneven surface is 1.0 μm or more and 10.0 μm or less in a 96 μm × 72 μm region on the uneven surface.

[0012] A water-repellent member according to aspect 4 of the present invention is a water-repellent member having irregularities on at least a part of its surface, characterized in that, in a 96 μm × 72 μm region on the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, the average length RSm of the roughness curve elements is 1.0 μm or more and 10.0 μm or less, and the arithmetic mean curvature Spc of the peak is 1500 / mm or more and 8000 / mm or less.

[0013] The water-repellent member of embodiment 5 comprises, in any one embodiment from embodiments 1 to 4, a member body having a first main surface and a second main surface facing each other, and a water-repellent coating provided on the first main surface of the member body, wherein the irregularities are preferably present on the surface of the water-repellent coating.

[0014] In embodiment 6, the water-repellent member is preferably such that the water-repellent coating is a thin film containing a fluoroalkyl group or alkyl group, or a polymer thin film consisting of a siloxane skeleton, as in embodiment 5.

[0015] The water-repellent member of embodiment 7 preferably further comprises a member body having a first main surface and a second main surface facing each other, in any one embodiment from embodiments 1 to 6, and an optical functional film provided on at least one of the first main surface and the second main surface of the member body, which overlaps with the irregularities in the direction in which the first main surface and the second main surface face each other.

[0016] In the water-repellent member of embodiment 8, it is preferable that the optical functional film is an anti-reflective film or a reflective film in embodiment 7.

[0017] The water-repellent member of embodiment 9 comprises a member body having a first main surface and a second main surface facing each other in any one embodiment from embodiment 1 to embodiment 8, and it is preferable that the member body is made of a light-transmitting material.

[0018] In the water-repellent member of embodiment 10, it is preferable that the light-transmitting material in embodiment 9 is a glass material or a ceramic material.

[0019] According to the present invention, it is possible to provide a water-repellent member that can achieve high water repellency and high productivity.

[0020] Figure 1 is a schematic cross-sectional view showing a water-repellent member according to the first embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing a water-repellent member according to the second embodiment of the present invention. Figure 3 is a schematic cross-sectional view showing a water-repellent member according to the third embodiment of the present invention. Figure 4 is a schematic cross-sectional view showing a water-repellent member according to the fourth embodiment of the present invention.

[0021] Preferred embodiments are described below. However, the following embodiments are merely illustrative, and the present invention is not limited to these embodiments. In addition, in each drawing, components having substantially the same function may be referred to by the same reference numerals.

[0022] (Water-repellent member) (First embodiment) Figure 1 is a schematic cross-sectional view showing a water-repellent member according to the first embodiment of the present invention.

[0023] The water-repellent member 1 has water-repellent properties on at least a portion of its surface. Specifically, the water-repellent member 1 has a member body 2. In this embodiment, the member body 2 has a rectangular flat plate shape. A rectangular flat plate shape refers to a flat plate shape in which the shape of the main surface is rectangular. However, the shape of the member body 2 is not limited to the above, and may be, for example, a flat plate shape in which the shape of the main surface is circular or polygonal, a flat plate shape that is curved overall, a spherical lens shape or an aspherical lens shape, etc.

[0024] In this embodiment, the material of the main body 2 of the component is a light-transmitting material. More specifically, a glass material is used as the light-transmitting material of the main body 2 of the component. Examples of glass materials used for the main body 2 of the component include quartz glass, soda-lime glass, alkali-free glass, aluminosilicate glass, borosilicate glass, phosphate glass, fluoride glass, or chalcogenide glass. The glass material may be partially crystallized glass, or it may be crystallized glass.

[0025] Furthermore, ceramic materials may be used as the light-transmitting material for the main body 2 of the component. In this case, examples of ceramic materials used for the main body 2 of the component include alumina, YAG (yttrium aluminum garnet), and Y ２ O ３ Examples include yttrium oxide, sapphire, or spinel.

[0026] The material used for the main body 2 is not particularly limited, and various materials can be used depending on the application. Examples of materials used for the main body 2 include alloys such as stainless steel, metals such as aluminum, metalloids such as germanium and silicon, resins such as acrylic and PPS (polyphenylene sulfide), or stones such as marble.

[0027] The material of the main body 2 of the component mentioned above may be one type alone, or multiple types may be used in combination.

[0028] The thickness of the main body 2 of the component is not particularly limited and can be, for example, 50 μm or more and 100 mm or less.

[0029] As shown in Figure 1, the member body 2 has a first main surface 2a and a second main surface 2b. The first main surface 2a and the second main surface 2b face each other. The entire surface of the first main surface 2a is provided with irregularities 2c. On the other hand, the second main surface 2b is not provided with irregularities 2c.

[0030] In this embodiment, the surface of the member body 2 is the surface of the water-repellent member 1. Therefore, the first main surface 2a and the second main surface 2b of the member body 2 are included in the surface of the water-repellent member 1. The water-repellent member 1 only needs to have irregularities 2c on at least a part of its surface. For example, the irregularities 2c may be provided on the entire surface of both the first main surface 2a and the second main surface 2b of the member body 2, or the irregularities 2c may be provided only on a part of the first main surface 2a.

[0031] Furthermore, it is preferable that the irregularities 2c are provided on 1% or more of the first main surface 2a of the member body 2, more preferably on 30% or more, and even more preferably on 50% or more.

[0032] The structures of the first to third inventions of this application are described below. In this specification, unless otherwise specified, the term "the present invention" refers collectively to the first to third inventions. The first to third inventions may be implemented individually or in combination.

[0033] The feature of the present invention is that in a region of 96 μm × 72 μm on a surface having irregularities, when the cut-off value of the high-pass filter λc is 25 μm and the cut-off value of the low-pass filter λs is 0.25 μm, it has the following parameters.

[0034] In the first invention of the present application, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the ratio Sa / RSm of the arithmetic mean height Sa to the average length RSm of the roughness curve elements is 10.0×10 －３ exceeds and is 30.0×10 －３ or less.

[0035] In the second invention of the present application, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the root mean square gradient Sdq of the contour surface is 0.15 or more and 0.70 or less.

[0036] In the third invention of the present application, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, the average length RSm of the roughness curve elements is 1.0 μm or more and 10.0 μm or less, and the arithmetic mean curvature Spc of the peaks is 1500 / mm or more and 8000 / mm or less.

[0037] The "arithmetic mean height Sa" is a parameter defined by ISO 25178, and is a parameter obtained by expanding a measurement cross-sectional curve showing the cross-sectional shape of the irregularities onto a plane. Specifically, the arithmetic mean height Sa can be obtained from the average of the absolute values of the heights Zn of the irregularities in a predetermined three-dimensional region (Sa = (Σ|Zn|) / n).

[0038] The "average length RSm of the roughness curve elements" is a parameter defined by JIS B 0601:2013, and is a parameter representing the average pitch between adjacent concave and convex portions in a contour curve showing the cross-sectional shape of the irregularities. Hereinafter, the "average length RSm of the roughness curve elements" may sometimes be simply referred to as "average length RSm".

[0039] The "arithmetic mean curvature of the peaks Spc" is a parameter defined by ISO 25178, which represents the average sharpness of the peaks included in a reference region of a contour surface. Here, a peak refers to a peak when the convex parts of a concave surface are considered as mountains. The arithmetic mean curvature of the peaks Spc is obtained from the arithmetic mean of the curvature of the peaks included in the reference region. In the arithmetic mean curvature of the peaks Spc, only the curvature of peaks higher than a predetermined height is considered. In this invention, the value of the predetermined height is 5% of the difference between the highest and lowest parts of the reference region. Hereinafter, "arithmetic mean curvature of the peaks Spc" may be simply referred to as "arithmetic mean curvature Spc".

[0040] The "root mean square gradient Sdq of a contour surface" is a parameter defined by ISO 25178, which extends the measured cross-sectional curve, which indicates the cross-sectional shape of the surface, to the surface itself. Specifically, the root mean square gradient Sdq of a contour surface is a parameter calculated by taking the root mean square of the slope at all points in the defined domain. Hereinafter, "root mean square gradient Sdq of a contour surface" may be simply referred to as "root mean square gradient Sdq".

[0041] In this invention, measurements are performed in a region of 96 μm × 72 μm, and the arithmetic mean height Sa, average length RSm, arithmetic mean curvature Spc, and root mean square gradient Sdq are determined by setting the cutoff value of the high-pass filter λc to 25 μm and the cutoff value of the low-pass filter λs to 0.25 μm. In this invention, the reference region for the arithmetic mean curvature Spc is a region of 96 μm × 72 μm. In the following, unless otherwise specified, when arithmetic mean height Sa, average length RSm, arithmetic mean curvature Spc, or root mean square gradient Sdq are mentioned, they refer to the arithmetic mean height Sa, average length RSm, arithmetic mean curvature Spc, or root mean square gradient Sdq measured under the above conditions.

[0042] The water-repellent member 1 of this embodiment has the above-described structure, and therefore can achieve high water repellency. In addition, in the present invention, the parameters of the irregularities 2c provided on the surface of the water-repellent member 1 only need to be within the range shown above. As a result, the water-repellent member 1 can be easily obtained without going through complex processes. Therefore, the water repellency of the water-repellent member 1 can be increased, and productivity can be increased.

[0043] More specifically, in the first invention of this application, by having an arithmetic mean height Sa of 15 nm or more, an air layer can be sufficiently maintained in the recesses of the uneven surface 2c, thereby increasing the water repellency of the water-repellent member 1.

[0044] The arithmetic mean height Sa is preferably 20 nm or more, more preferably 25 nm or more, even more preferably 30 nm or more, even more preferably 35 nm or more, and particularly preferably 40 nm or more. This allows an air layer to be effectively maintained in the recesses of the uneven surface 2c. This effectively increases the water repellency of the water-repellent member 1.

[0045] On the other hand, by having an arithmetic mean height Sa of 200 nm or less, light scattering can be suppressed. This makes it possible to suppress the clouding of the main body of the component 2.

[0046] The arithmetic mean height Sa is preferably 190 nm or less, more preferably 180 nm or less, even more preferably 170 nm or less, even more preferably 160 nm or less, and particularly preferably 150 nm or less.

[0047] The preferred range for the arithmetic mean height Sa described above is also the same for the second and third inventions of this application.

[0048] In addition, in the first invention of this application, the ratio of the arithmetic mean height Sa to the average length RSm, Sa / RSm, is 10.0 × 10 －３By exceeding this value, the aspect ratio of the unevenness 2c can be made sufficiently large, and it becomes difficult for water to penetrate into the concave portion of the unevenness 2c. As a result, an air layer can be more reliably retained in the concave portion of the unevenness 2c. Thereby, the water repellency of the water repellent member 1 can be enhanced.

[0049] The ratio Sa / RSm is 12.0×10 －３ or more, preferably 14.0×10 －３ or more, more preferably 16.0×10 －３ or more.

[0050] On the other hand, when the ratio Sa / RSm is 30.0×10 －３ or less, it is possible to suppress the shape of the convex portion in the unevenness 2c from becoming too sharp. Thereby, it becomes difficult to damage the unevenness 2c.

[0051] The ratio Sa / RSm is 28.0×10 －３ or less, preferably 26.0×10 －３ or less, more preferably 24.0×10 －３ or less. Thereby, it becomes effectively difficult to damage the unevenness 2c.

[0052] In the second invention of the present application, similar to the first invention, the arithmetic mean height Sa is 15 nm or more and 200 nm or less. Thereby, the water repellency of the water repellent member 1 can be enhanced, and clouding of the member main body 2 can be suppressed.

[0053] In addition, in the second invention of the present application, when the root mean square gradient Sdq is 0.15 or more, the gradient of the unevenness 2c can be made sufficiently large, and it becomes difficult for water to penetrate into the concave portion of the unevenness 2c. As a result, an air layer can be more reliably retained in the concave portion of the unevenness 2c. Thereby, the water repellency of the water repellent member 1 can be enhanced.

[0054] The root mean square gradient Sdq is preferably 0.20 or higher, more preferably 0.25 or higher, and even more preferably 0.30 or higher. This allows an air layer to be effectively maintained in the recesses of the uneven surface 2c. As a result, the water repellency of the water-repellent member 1 can be effectively increased.

[0055] On the other hand, if the root mean square gradient Sdq is 0.70 or less, light scattering can be suppressed. This makes it possible to suppress the clouding of the main body of the component 2.

[0056] The root mean square gradient Sdq is preferably 0.65 or less, more preferably 0.60 or less, and even more preferably 0.55 or less. This effectively suppresses the clouding of the main body of the component 2.

[0057] In the first and second inventions, the average length RSm is preferably 1.0 μm or more, more preferably 1.5 μm or more, and even more preferably 2.0 μm or more. On the other hand, the average length RSm is preferably 10.0 μm or less, more preferably 8.0 μm or less, even more preferably 6.0 μm or less, and particularly preferably 4.0 μm or less. This makes it possible to more reliably and effectively increase the water repellency of the water-repellent member 1.

[0058] Furthermore, the preferred range for the average length RSm described above is the same in the third invention.

[0059] In the third invention of this application, similar to the first invention, the arithmetic mean height Sa is 15 nm or more and 200 nm or less. This makes it possible to increase the water repellency of the water-repellent member 1 and suppress the clouding of the member body 2.

[0060] In addition, in the third invention of this application, since the arithmetic mean curvature Spc is 1500 / mm or more, the convex portions of the unevenness 2c are sufficiently sharp, making it difficult for water to penetrate into the concave portions of the unevenness 2c. This allows for a more reliable retention of the air layer in the concave portions of the unevenness 2c. As a result, the water repellency of the water-repellent member 1 can be increased.

[0061] The arithmetic mean curvature Spc is preferably 2000 / mm or more, more preferably 2500 / mm or more, even more preferably 3000 / mm or more, even more preferably 3500 / mm or more, and particularly preferably 4000 / mm or more. This effectively increases the water repellency of the water-repellent member 1.

[0062] On the other hand, by keeping the arithmetic mean curvature Spc below 8000 / mm, it is possible to suppress the shape of the protrusions in the uneven surface 2c from becoming too sharp. This makes the uneven surface 2c less susceptible to damage.

[0063] The arithmetic mean curvature Spc is preferably 7500 / mm or less, more preferably 7000 / mm or less, even more preferably 6500 / mm or less, even more preferably 6200 / mm or less, and particularly preferably 6000 / mm or less. This effectively makes the uneven surface 2c less susceptible to damage.

[0064] Furthermore, in the third invention of this application, the average length RSm is 1.0 μm or more and 10.0 μm or less. By setting the average length RSm within this range, the water repellency of the water-repellent member 1 can be made more reliably high.

[0065] (Method for manufacturing water-repellent member) Next, an example of a method for manufacturing the water-repellent member 1 will be described.

[0066] The irregularities 2c on the surface of the water-repellent member 1 can be formed, for example, by applying a surface treatment such as wet blasting to the first main surface 2a of the member body 2.

[0067] Wet blasting is a process that creates fine irregularities on a workpiece by uniformly mixing abrasive particles, which are composed of solid particles such as alumina, with a liquid such as water to form a slurry, and then using compressed air to spray this slurry at high speed from a nozzle onto a workpiece made of glass, ceramic, or the like.

[0068] In wet blasting, when a slurry is ejected at high speed and collides with a workpiece, the abrasive particles in the slurry scrape, strike, and rub against the surface of the workpiece, creating fine irregularities on the workpiece surface.

[0069] In this case, the abrasive particles sprayed onto the workpiece, as well as the fragments of the workpiece removed by the abrasive particles, are washed away by the liquid sprayed onto the workpiece, resulting in fewer particles remaining on the workpiece.

[0070] In wet blasting, when slurry is sprayed onto the workpiece, the liquid carries the abrasive particles to the workpiece. This makes it easier to use finer abrasive particles compared to dry sandblasting, and also reduces the impact when the abrasive particles collide with the workpiece, enabling precise machining.

[0071] In wet blasting, the particle size of the abrasive grains can be, for example, an average particle size of 0.2 μm or more and 60 μm or less. The air pressure when spraying the slurry containing abrasive grains can be, for example, 0.11 MPa or more, 0.20 MPa or more, 0.25 MPa or more, 0.30 MPa or more, or 0.31 MPa or more. On the other hand, the air pressure when spraying the slurry containing abrasive grains can be, for example, 0.50 MPa or less and 0.40 MPa or less. The projection distance of the slurry onto the workpiece, i.e., the glass plate, can be, for example, 100 mm or less, 80 mm or less, 50 mm or less, 30 mm or less, 10 mm or less, or 8 mm or less. Furthermore, the scanning speed of the nozzle can be, for example, 0.1 mm / s or more and 200 mm / s or less. The average particle size of the abrasive grains can be measured, for example, by the electrical resistance method.

[0072] Furthermore, the arithmetic mean height Sa of the first main surface 2a of the member body 2 can be increased by increasing the average particle size of the abrasive grains in the wet blasting process, increasing the air pressure when spraying the slurry, shortening the projection distance of the slurry, or slowing down the scanning speed of the nozzle.

[0073] By reducing the average particle size of abrasive grains in wet blasting, reducing the air pressure when spraying the slurry, shortening the slurry projection distance, and increasing the scanning speed of the nozzle, the average length RSm and the root mean square gradient Sdq of the irregularities 2c in the water-repellent member 1 can be reduced.

[0074] By the way, as described above, in the first embodiment shown in Figure 1, the entire surface of the first main surface 2a of the member body 2 is provided with irregularities 2c. However, the irregularities 2c may be provided only on a part of the first main surface 2a. An example of this is shown below.

[0075] (Water-repellent member) (Second embodiment) Figure 2 is a schematic cross-sectional view showing a water-repellent member according to the second embodiment.

[0076] This embodiment differs from the first embodiment in that a portion of the first main surface 12a of the member body 12 is provided with irregularities 2c.

[0077] In the water-repellent member 11, the first main surface 12a of the member body 12 is provided with an unprocessed portion 13. Specifically, the unprocessed portion 13 is the part that has not been processed to provide the irregularities 2c. In this embodiment, the entire second main surface 12b of the member body 12 is also an unprocessed portion 13. However, in the present invention, irregularities 2c may also be provided on the second main surface 12b of the member body 12.

[0078] The water-repellent member 11 in this embodiment has the configuration of the first, second, or third invention of this application as described above. As a result, the water repellency of the water-repellent member 11 can be increased, and productivity can be increased, similar to the first embodiment.

[0079] In this invention, the water-repellent member exhibits excellent water repellency even without a water-repellent coating. However, the water-repellent member may have a water-repellent coating. An example of this is shown below.

[0080] (Third Embodiment) Figure 3 is a schematic cross-sectional view showing a water-repellent member according to the third embodiment.

[0081] This embodiment differs from the first embodiment in that a water-repellent coating 24 is provided on the first main surface 2a of the member body 2 so as to cover the irregularities 2c. In this embodiment, the surface 24a of the water-repellent coating 24 is part of the surface of the water-repellent member 21.

[0082] The member body 2 in this embodiment is configured in the same way as the member body 2 in the first embodiment. Therefore, the parameters of the irregularities 2c of the member body 2 are the same as the parameters of the irregularities in the first, second, or third inventions of this application described above. In this embodiment, the surface shape of the water-repellent coating 24 reflects the irregularities 2c of the member body 2. Therefore, the surface 24a of the water-repellent coating 24 also has irregularities 24c similar to the irregularities 2c on the first main surface 2a of the member body 2. Thus, the water-repellent member 21 has the configuration of the first, second, or third invention of this application. This makes it possible to effectively increase the water repellency of the water-repellent member 21 and increase productivity.

[0083] The thickness of the water-repellent coating 24 is preferably, for example, 0.1 nm or more and 20 nm or less. In this case, the parameters of the irregularities 24c on the surface 24a of the water-repellent coating 24 can be easily made to be approximately the same as the parameters of the irregularities 2c on the first main surface 2a of the member body 2. However, the thickness of the water-repellent coating 24 is not limited to the above.

[0084] Furthermore, the irregularities 24c may be formed after the water-repellent coating 24 has been formed. In this case, it is preferable to form the water-repellent coating 24 such that the thickness of the water-repellent coating 24 is greater than the difference in height between the protrusions and recesses in the irregularities to be formed. In this case, the parameters of the irregularities 2c of the member body 2 do not need to be the same as the parameters of the irregularities in the first, second, or third inventions of this application described above. Alternatively, the member body 2 does not need to have irregularities 2c and may be smooth.

[0085] When the uneven surface 24c is formed after the water-repellent coating 24 is formed, the water repellency of the water-repellent member 21 can be made more effective, and productivity can be increased.

[0086] In this embodiment, only a water-repellent coating 24 is provided on the first main surface 2a of the member body 2 so as to cover the uneven surface 2c. However, layers other than the water-repellent coating 24 may be provided on the first main surface 2a. In this case as well, it is preferable that the water-repellent coating 24 is the outermost layer among the layers provided so as to cover the uneven surface 2c. In other words, it is preferable that the surface 24a of the water-repellent coating 24 is part of the surface of the water-repellent member 21, and that the uneven surface according to the present invention is provided on the surface 24a of the water-repellent coating 24. This configuration has the uneven surface according to the present invention on the surface 24a of the water-repellent coating 24. This makes it possible to more reliably exhibit the function of increasing the water repellency of the water-repellent coating 24. Accordingly, the water repellency of the water-repellent member 21 can be increased more reliably and effectively.

[0087] It is preferable that the water-repellent coating 24 is a thin film containing a fluoroalkyl group or an alkyl group, or a polymer thin film consisting of a siloxane skeleton. Furthermore, if the water-repellent coating 24 is a thin film containing a fluoroalkyl group or an alkyl group, it is more preferable that the water-repellent coating 24 is a monolayer containing a fluoroalkyl group or an alkyl group. This further enhances the water repellency of the water-repellent member 21.

[0088] A thin film containing a fluoroalkyl group or alkyl group may specifically be, for example, a thin film of a silane compound containing a fluoroalkyl group or alkyl group. The number of carbon atoms in the fluoroalkyl group or alkyl group is, for example, 1 to 40. The fluoroalkyl group or alkyl group may have a linear structure or a branched structure with side chains. The fluoroalkyl group or alkyl group may have ether bonds or the like. One of these materials may be used alone, or multiple materials may be used in mixture form.

[0089] Examples of polymer thin films consisting of a siloxane skeleton include polymer thin films containing methyl silicone resin, methylphenyl silicone resin, alkyd-modified silicone resin, epoxy-modified silicone resin, acrylic-modified silicone resin, polyester-modified silicone resin, or fluorine-modified silicone resin.

[0090] Examples of commercially available materials for forming the water-repellent film 24 include fluorine-based antifouling coating agents (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KY-1908"), fluorine-based antifouling coating agents (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-71-195"), antifouling coating agents (manufactured by Daikin Corporation, product name "UD509"), antifouling coating agents (manufactured by Daikin Corporation, product name "UD120"), or super water-repellent coating materials (manufactured by DON Corporation, product name "SH-HT").

[0091] On the other hand, from an environmental perspective, it is preferable that the water-repellent film 24 is substantially free of fluorine, and particularly preferable that it is substantially free of organofluorine compounds. In this case, the material used to form the water-repellent film 24 may be, for example, a polysiloxane-based coating agent. Examples of commercially available polysiloxane-based coating agents include silicone oligomer-based coating agents (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KR-400"), silicone oligomer-based coating agents (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-40-2327"), silicone oligomer-based coating agents (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KR-4000G"), silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.), and glass resin-based coating agents (manufactured by Techneglas, "GR-630S").

[0092] Furthermore, "substantially free of fluorine" means that the fluorine content in the water-repellent coating 24 is 1 atom% or less, and naturally, it is also acceptable for the water-repellent coating 24 to contain no fluorine at all. "Substantially free of organic fluorine compounds" means that the organic fluorine content in the water-repellent coating 24 is 1 mass% or less, and naturally, it is also acceptable for the water-repellent coating 24 to contain no organic fluorine compounds at all.

[0093] The water-repellent coating 24 can be formed by a spray coating method, spin coating method, dip coating method, or vacuum deposition method, etc.

[0094] Similar to the first embodiment, the first main surface 2a of the member body 2 in the water-repellent member 21 has irregularities 2c formed thereon. As a result, even if the water-repellent coating 24 is worn away or peeled off due to friction such as rubbing, the water-repellent member 21 is given high water repellency due to the irregularities 2c. This makes it possible to maintain high water repellency over a long period of time.

[0095] The thickness of the water-repellent coating 24 is preferably 0.1 nm or more, more preferably 1.1 nm or more, even more preferably 1.5 nm or more, and particularly preferably 2 nm or more. When the thickness of the water-repellent coating 24 is equal to or greater than the above lower limit, the water repellency of the water-repellent member 21 can be further enhanced.

[0096] On the other hand, the thickness of the water-repellent coating 24 is preferably 20 nm or less, more preferably 15 nm or less, even more preferably 12 nm or less, even more preferably 10 nm or less, even more preferably 7 nm or less, and particularly preferably 5 nm or less. When the thickness of the water-repellent coating 24 is below the above upper limit, deterioration of the optical properties of the water-repellent member 21 is even less likely to occur.

[0097] The thickness of the water-repellent coating 24 may be measured by X-ray reflectivity or spectroscopic ellipsometry. Alternatively, the thickness of the water-repellent coating 24 may be measured by observing a cross-section of the water-repellent coating 24 with a microscope such as a transmission electron microscope (TEM).

[0098] (Fourth Embodiment) Figure 4 is a schematic cross-sectional view showing a water-repellent member according to the fourth embodiment.

[0099] This embodiment differs from the third embodiment in that an optical functional film 35 is provided on the first main surface 2a of the member body 2 so as to cover the uneven surface 2c. Specifically, an optical functional film 35 is provided on the first main surface 2a of the member body 2. A water-repellent coating 24 is provided on the optical functional film 35. Thus, the water-repellent coating 24 is the outermost layer among the layers provided to cover the uneven surface 2c.

[0100] The member body 2 in this embodiment is configured in the same way as the member body 2 in the first and third embodiments. Therefore, the parameters of the irregularities 2c of the member body 2 are the same as the parameters of the irregularities in the first, second, or third inventions of this application described above. The surface of the optical functional film 35 also has irregularities similar to the irregularities 2c on the first main surface 2a of the member body 2. Furthermore, the surface 24a of the water-repellent coating 24 also has irregularities 24c similar to the irregularities 2c on the first main surface 2a of the member body 2. Therefore, in this embodiment as well as in the third embodiment, the water repellency of the water-repellent member 31 can be effectively increased and productivity can be increased.

[0101] As the optical functional film 35, for example, an anti-reflective film or a reflective film can be used. For example, as the anti-reflective film, a low refractive index film with a refractive index lower than that of the main body of the component 2 can be used. Alternatively, for example, as the anti-reflective film, a dielectric multilayer film is used in which a low refractive index film with a relatively low refractive index and a high refractive index film with a relatively high refractive index are alternately laminated. On the other hand, for example, as the reflective film, a metal film can be used. Alternatively, for example, as the reflective film, a dielectric multilayer film is used in which a low refractive index film with a relatively low refractive index and a high refractive index film with a relatively high refractive index are alternately laminated.

[0102] Anti-reflective coatings and reflective coatings can be formed by sputtering or CVD methods, etc.

[0103] The thickness of the optical functional film 35 is not particularly limited, as long as it does not hinder the effects of the present invention described above, and can be, for example, 1 nm or more and 5 μm or less.

[0104] The optical functional film 35 only needs to be provided on at least one of the first main surface 2a and the second main surface 2b of the member body 2. The optical functional film 35 only needs to overlap with the irregularities 2c in the direction in which the first main surface 2a and the second main surface 2b are facing each other.

[0105] In the present invention, the water-repellent coating 24 is not necessarily provided. The surface of the optical functional film 35 may be part of the surface of the water-repellent member 31. In this case, the surface of the optical functional film 35 may have irregularities similar to those on the first main surface 2a of the member body 2 in the first embodiment. This makes it possible to effectively increase the water repellency of the water-repellent member 31 and to increase productivity.

[0106] The present invention will be described in more detail below based on specific examples. The present invention is not limited in any way to the following examples, and can be implemented with appropriate modifications without changing its essence.

[0107] (Examples 1-10) In Examples 1-10, first, a glass plate made of aluminosilicate glass (manufactured by Nippon Electric Glass Co., Ltd., product name "T2X-1") was prepared as the main component. More specifically, the glass plate prepared was a rectangular flat glass plate with a thickness of 1.1 mm.

[0108] Next, a wet blasting treatment was applied to the entire main surface of one side of the prepared glass plate to create an uneven surface.

[0109] For the wet blasting treatment, a slurry containing 3 wt% abrasive particles and 97 wt% water was first prepared by uniformly stirring abrasive particles made of alumina with an average particle size of 2.0 μm or 3.0 μm with water.

[0110] Next, wet blasting was performed on the entire main surface of one of the glass plates by spraying the slurry from a nozzle. Specifically, the slurry was sprayed from a nozzle with a 1 mm x 1 mm nozzle opening, which was positioned so that the projection distance was 2 mm to 6 mm, while scanning the nozzle. The processing air pressure was set to 0.22 MPa to 0.32 MPa during slurry spraying. The nozzle scanning was performed in rows in two mutually orthogonal directions. In other words, the nozzle scanning was performed in a grid pattern. More specifically, the nozzle was scanned in one direction with a scanning interval of 350 μm, and then scanned in a direction perpendicular to that direction with a scanning interval of 350 μm. The scanning speed of the nozzle was set to 2.5 mm / s to 50 mm / s.

[0111] Next, a water-repellent coating was formed on the main surface of the glass plate that had undergone wet blasting treatment.

[0112] For the formation of the water-repellent coating, first, a solution was prepared by diluting a coating agent containing a fluoroalkyl group (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KY-1908") with a fluorine-based solvent (manufactured by 3M, product name "Novec7200") to a concentration of 0.2 wt% of the coating agent. Next, the organic film was formed by applying the above solution to the main surface of a glass plate that had undergone wet blasting treatment using spin coating.

[0113] Next, the glass plate on which the organic film was formed was heated at 120°C for 2 hours to cure the organic film, thereby forming a water-repellent coating.

[0114] (Example 11) In Example 11, a water-repellent member was manufactured in the same manner as in Examples 1 to 10, except that the main body of the member was made of a rectangular flat stainless steel (SUS304) with a thickness of 2.0 mm.

[0115] (Example 12) In Example 12, the water-repellent coating was made into a fluorine-free film, i.e., a film substantially free of fluorine, and the water-repellent member was manufactured in the same manner as in Example 3, except for the film formation method. More specifically, a polysiloxane-based coating agent (manufactured by Nippon Electric Glass Co., Ltd.) was prepared for the formation of the water-repellent coating. Next, the above coating agent was applied by spray coating to the main surface of the glass plate that had been wet-blasted to form an organic film. Next, the glass plate on which the above organic film was formed was heated to cure the organic film, thereby forming a water-repellent coating.

[0116] The manufacturing conditions for the water-repellent members in Examples 1 to 12 are shown in Table 1 below. In Table 1, "○" in the Chemical Etching column indicates that chemical etching treatment was performed. On the other hand, "×" indicates that chemical etching treatment was not performed. In Examples 1 to 12, no chemical etching treatment was performed, so all entries are "×".

[0117]

[0118] (Comparative Examples 1-4) Except for the fact that the average particle size of the alumina abrasive grains was 1.2 μm, 2.0 μm, or 3.0 μm during the wet blasting process, the projection distance was 2 mm to 4 mm, and the nozzle scanning speed was 0.5 mm / s to 1.0 mm / s, the water-repellent members were manufactured in the same manner as in Examples 1-10.

[0119] (Comparative Example 5) A water-repellent member was prepared in the same manner as in Examples 1 to 10, except that the glass plate was not subjected to wet blasting.

[0120] (Comparative Example 6) In Comparative Example 6, a glass plate was prepared in the same manner as in Examples 1 to 10. Next, preliminary irregularities were formed on the entire main surface of one side of the prepared glass plate by wet blasting. Preliminary irregularities refer to irregularities that serve as the starting point for etching.

[0121] For the wet blasting treatment, a slurry containing 10 wt% abrasive particles and 90 wt% water was first prepared by uniformly stirring abrasive particles made of alumina with an average particle size of 6.9 μm with water.

[0122] Next, wet blasting was performed on the entire main surface of one of the glass plates by spraying the slurry from a nozzle. Specifically, the slurry was sprayed from a nozzle with a nozzle opening of 1 mm x 320 mm while scanning the nozzle. The processing air pressure was set to 0.15 MPa when spraying the slurry. The scanning speed of the nozzle was set to 5.0 mm / s.

[0123] Next, the glass plate that had been wet-blasted was subjected to chemical etching. For the chemical etching, an etching solution was prepared by first immersing the wet-blasted glass plate in the etching solution, which was heated to 30°C, for 180 seconds. This chemical etching process created the final surface texture on the glass plate, moving from the initial surface texture to the final texture.

[0124] Next, a water-repellent coating was formed on the main surface of the glass plate where the irregularities were created, in the same manner as in Examples 1 to 10.

[0125] (Comparative Example 7) A water-repellent member was prepared in the same manner as in Example 12, except that the glass plate was not subjected to wet blasting.

[0126] The conditions for producing the water-repellent members in Comparative Examples 1 to 7 are shown in Table 1 above.

[0127] (Evaluation) [Measurement of surface shape] Surface roughness parameters of the main surfaces of the water-repellent members of Examples 1 to 12 and Comparative Examples 1 to 7, which were the subject of evaluation, were measured using a laser microscope (Keyence Corporation, part number "VK-X250"). The average length RSm was measured in accordance with JIS B 0601:2013. The arithmetic mean height Sa, arithmetic mean curvature Spc, and root mean square gradient Sdq were measured in accordance with ISO 25178.

[0128] Each surface roughness parameter was measured using a 150x objective lens, with a measurement area of ​​96 μm × 72 μm, resulting in 2048 × 1536 pixels of acquired data. After removing the plane's inclination using the least squares method, height noise was removed by setting the height cutoff level threshold to 50. The cutoff value of the high-pass filter λc was set to 25 μm, and the cutoff value of the low-pass filter λs was set to 0.25 μm, and the analysis was performed. For the measurement of the average length RSm, the average value calculated from five horizontal lines per measurement area was used.

[0129] [Measurement of Water Contact Angle] The water contact angle was measured based on the static drop method (θ / 2 approximation method) of JIS R 3257:1999. Specifically, the water-repellent members of Examples 1 to 12 and Comparative Examples 1 to 7 were placed horizontally with the main surface to be evaluated facing upwards, and 2 μL of pure water was dropped onto the main surface. Then, the water droplet was photographed from directly beside it using a digital scope (Keyence Corporation, model number "VHX-500F"), and the contact angle was measured.

[0130] [Measurement of Haze and Total Light Transmittance] The haze and total light transmittance of the water-repellent members in Examples 1 to 10, 12 and Comparative Examples 1 to 7 were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model number "NDH-8000SP") in accordance with JIS K 7361-1-1997. In Example 11, a rectangular flat stainless steel plate was used for the member body. Therefore, the haze and total light transmittance of the water-repellent member in Example 11 were not measured.

[0131] [Evaluation Results] The evaluation results are shown in Table 2 below.

[0132]

[0133] In Examples 1 to 11, which used a fluorine-based water-repellent coating, the water contact angle was high, at 126° or higher. On the other hand, in Comparative Examples 1 to 6, the water contact angle was 121° or lower, which was lower than in each of the examples.

[0134] When comparing Example 12 and Comparative Example 7, both of which used a fluorine-free water-repellent coating, Example 12 showed a sufficiently high water contact angle of 116°. On the other hand, Comparative Example 7 showed a lower water contact angle of 103° compared to Example 12.

[0135] In Examples 1-9 and 12, the haze was 8.2% or less. In Example 10, the haze was 20.0%. However, in all of Examples 1-10 and 12, the total light transmittance was sufficiently high at 91.3% or more.

[0136] The water-repellent members of Examples 1 to 12 have the configurations of the first to third inventions of this application. Specifically, in Examples 1 to 12, the arithmetic mean height Sa was between 27.4 nm and 69.8 nm. It was confirmed that the arithmetic mean height Sa tends to increase as the average particle size of the abrasive grains in the wet blasting treatment and the processing air pressure increase.

[0137] In addition, in Examples 1 to 12, the root mean square gradient Sdq was 0.22 or more and 0.48 or less, the arithmetic mean curvature Spc was 2305.0 / mm or more and 5643.6 / mm or less, and the average length RSm was 2.2 nm or more and 3.6 nm or less. Furthermore, in Examples 1 to 12, the ratio of the arithmetic mean height Sa to the average length RSm Sa / RSm was 11.2 × 10⁻⁶. －３ The above is 21.3 x 10 －３ The results were as follows:

[0138] In Examples 1 to 12, the nozzle scanning speed during wet blasting was set to 2.5 mm / s to 50 mm / s. On the other hand, in Comparative Examples 1 to 4, the scanning speed was set to 0.5 mm / s to 1 mm / s. As a result, the values ​​of the ratio Sa / RSm, the root mean square gradient Sdq, and the arithmetic mean curvature Spc were all relatively small. Specifically, in Comparative Examples 1 to 4, the ratio Sa / RSm was 4.3 × 10⁻⁶. －３ The above is 5.9 x 10 －３ The results were as follows: the root mean square gradient Sdq was between 0.10 and 0.14, and the arithmetic mean curvature Spc was between 1028.6 / mm and 1331.7 / mm.

[0139] In Comparative Examples 5 and 7, wet blasting and chemical etching were not performed, and no irregularities were formed on the main surface of the glass plate. Therefore, in Comparative Examples 5 and 7, the average length RSm could not be measured, and the ratio Sa / RSm could not be calculated. In addition, the values ​​of the root mean square gradient Sdq and the arithmetic mean curvature Spc were both small. Specifically, in Comparative Example 5, the root mean square gradient Sdq was 0.02 and the arithmetic mean curvature Spc was 260.1 / mm. In Comparative Example 7, the root mean square gradient Sdq was 0.02 and the arithmetic mean curvature Spc was 265.1 / mm.

[0140] In Comparative Example 6, the average particle size of the abrasive grains in the wet blasting treatment was increased to 6.9 μm. In addition, a chemical etching treatment was performed after the wet blasting treatment. As a result, the values ​​of the ratio Sa / RSm, the root mean square gradient Sdq, and the arithmetic mean curvature Spc were all relatively small. Specifically, in Comparative Example 6, the ratio Sa / RSm was 4.8 × 10⁻⁶. －３ As a result, the root mean square gradient Sdq was 0.04, and the arithmetic mean curvature Spc was 321.4 / mm.

[0141] Based on the above, it was confirmed that the water repellency of a water-repellent component can be improved by controlling the surface roughness parameter of the water-repellent component.

[0142] The present invention is particularly useful when applied to components where water repellency is desired, such as window components, camera and sensor lens components, cover components, and mirror components. However, it is not limited to these, and the present invention can also be applied to components where stain resistance is desired. For example, it can be suitably used in displays such as those in mobile phones, tablet devices, televisions, or digital signage, and is even more suitably used in cover glass of touch panel displays.

[0143] 1...Water-repellent member 2...Member body 2a, 2b...First and second main surfaces 2c...Rubber surface 11...Water-repellent member 12...Member body 12a, 12b...First and second main surfaces 13...Unprocessed part 21...Water-repellent member 24...Water-repellent coating 24a...Surface 24c...Rubber surface 31...Water-repellent member 35...Optical functional film

Claims

1. A water-repellent member having irregularities on at least a portion of its surface, wherein in a 96 μm × 72 μm region of the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the ratio Sa / RSm of the arithmetic mean height Sa to the average length RSm of the roughness curve elements is 10.0 × 10 －３ It exceeds 30.0 x 10 －３ The following are water-repellent materials.

2. A water-repellent member having irregularities on at least a portion of its surface, wherein, in a 96 μm × 72 μm region of the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, and the root mean square gradient Sdq of the contour surface is 0.15 or more and 0.70 or less.

3. The water-repellent member according to claim 1 or 2, wherein in a 96 μm × 72 μm region of the surface having irregularities, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the average length RSm of the roughness curve elements of the irregularities is 1.0 μm or more and 10.0 μm or less.

4. A water-repellent member having irregularities on at least a portion of its surface, wherein, in a 96 μm × 72 μm region of the irregular surface, when the cutoff value of the high-pass filter λc is 25 μm and the cutoff value of the low-pass filter λs is 0.25 μm, the arithmetic mean height Sa is 15 nm or more and 200 nm or less, the average length RSm of the roughness curve elements is 1.0 μm or more and 10.0 μm or less, and the arithmetic mean curvature Spc of the peaks is 1500 / mm or more and 8000 / mm or less.

5. A water-repellent member according to any one of claims 1, 2, or 4, comprising: a member body having a first main surface and a second main surface facing each other; and a water-repellent coating provided on the first main surface of the member body, wherein the irregularities are present on the surface of the water-repellent coating.

6. The water-repellent member according to claim 5, wherein the water-repellent coating is a thin film containing a fluoroalkyl group or an alkyl group, or a polymer thin film consisting of a siloxane skeleton.

7. A water-repellent member according to any one of claims 1, 2, or 4, further comprising a member body having a first main surface and a second main surface facing each other, and an optical functional film provided on at least one of the first main surface and the second main surface of the member body, which overlaps with the irregularities in the direction in which the first main surface and the second main surface face each other.

8. The water-repellent member according to claim 7, wherein the optical functional film is an anti-reflective film or a reflective film.

9. A water-repellent member according to any one of claims 1, 2, or 4, comprising a member body having a first main surface and a second main surface facing each other, wherein the member body is made of a light-transmitting material.

10. The water-repellent member according to claim 9, wherein the light-transmitting material is a glass material or a ceramic material.

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