Snow accretion suppression sheet-like member

Abstract

To provide a snow accretion suppression sheet-like member which generates a snow accretion suppression effect by randomly forming numerous dome-shaped fine projections thereon.SOLUTION: A snow accretion suppression sheet-like member has a surface randomly having numerous dome-shaped fine projections, in which the surface is water repellent. Ra of the surface is within a range of 3.34 μm being a maximum value to 1.41 μm being a minimum value, Rz of the surface is within a range of 18.44 μm being a maximum value to 8.24 μm being a minimum value, or RSm of the surface is within a range of 337.46 μm being a maximum value to 152.98 μm being a minimum value, and a contact angle of water of the surface is 90° or more. The snow accretion suppression sheet-like member can have an Si-based film on the surface. The contact angle of the water on the surface of the Si-based film can be set at 108° or more. The snow accretion suppression sheet-like member is made of a resin, rubber, and an elastomer material.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a snow accretion prevention technology for preventing snow and ice from adhering to the surfaces of articles such as members, parts, and products.

[0002] BACKGROUND ART In recent years, LED lighting devices using LEDs (Light Emitting Diodes) have been adopted in many fields. For example, it is used in headlights, turn signals, brake lights, vehicle width, etc. of vehicles such as automobiles. Generally, LEDs emit light at low temperatures, so their surface temperatures are relatively low, meaning that they cannot melt snow that has accumulated on the surface of the lighting device, and the snow grows until the surface of the lighting device is covered with snow, potentially impairing its functionality. For this reason, there is a need for technology to prevent snow accumulation (including icing). The same is true for traffic lights, displays, and other devices that use LED lighting.

[0003] Therefore, technologies such as those described in Patent Documents 1 and 2 have been proposed as techniques for suppressing snow adhesion, but these are based on the idea that snow and ice adhesion can be suppressed by coating various items with a hydrophilic coating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-38410 [Patent Document 2] Japanese Patent Application Publication No. 2022-100499 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have been exploring the possibility of applying surface modification technology, which involves randomly forming countless microscopic irregularities on the surface of a component, to various fields. When they tested whether this technology could be applied to preventing snow from adhering to the surface of an item, they gained knowledge about surfaces that have a good snow-adhesion prevention effect.

[0006] The present invention has been developed in consideration of the above-mentioned situation, and aims to provide a snow accumulation suppression sheet-like member that has a snow accumulation suppression effect by randomly forming countless dome-shaped micro-protrusions on its surface. [Means for solving the problem]

[0007] The snow accretion suppression sheet member according to the present invention comprises: It has a surface with countless randomly distributed dome-shaped micro-projections, Its surface is characterized by being water-repellent.

[0008] In the present invention, The Ra (μm) of the surface is in the range of a maximum value of 3.34 μm to a minimum value of 1.41 μm, or the Rz (μm) of the surface is in the range of a maximum value of 18.44 μm to a minimum value of 8.24 μm, or the RSm (μm) of the surface is in the range of a maximum value of 337.46 μm to a minimum value of 152.98 μm, In addition, the contact angle of water on the surface is 90° or more.

[0009] The present invention may be characterized in that a Si-based coating is provided on the surface.

[0010] In the present invention, the contact angle of water on the surface of the Si-based coating film may be 108° or more.

[0011] The snow accretion suppression sheet member according to the present invention can be characterized by being made of at least one of a resin material, a rubber material, and an elastomer material. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a snow accretion-suppressing sheet member that has a snow accretion suppression effect by forming countless dome-shaped minute protrusions randomly on its surface. [Brief explanation of the drawings]

[0013] [Figure 1] (A) is a diagram showing an example of step 1 of a method for producing a snow accretion suppression transfer sheet (snow accretion suppression sheet-like member) by transfer in one embodiment of the present invention, (B) is a diagram showing step 2, (C) is a diagram showing step 3, (D) is a diagram showing step 4, (E) is a diagram showing step 5, (F) is a diagram showing step 6, and (G) is a diagram showing step 7. [Figure 2] 10A and 10B are diagrams showing examples of 3D images of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2" which are snow accretion suppression transfer sheets according to the embodiment. [Figure 3] 10A and 10B are diagrams showing examples of 3D images of the surfaces (transfer surfaces) of the molds "AS-1 mold" and "AS-2 mold" used to form the snow accretion suppression transfer sheet according to the embodiment. [Figure 4] 10 is a diagram showing an example of shape data of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2" which are snow accretion suppression transfer sheets according to the embodiment of the present invention. FIG. [Figure 5] 10 is a diagram showing an example of shape data of the surfaces (transfer surfaces) of the molds "AS-1 mold" and "AS-2 mold" used to mold the snow accretion suppression transfer sheet according to the embodiment. FIG. [Figure 6] 10A and 10B are diagrams showing SEM images of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2," which are snow accumulation suppression transfer sheets according to the embodiment of the present invention. [Figure 7]1A is a diagram showing the Ra (μm), Rz (μm), and RSm (μm) of the surfaces of the mold "AS-1mold," mold "AS-2mold," sample "AS-1," and sample "AS-2" according to the embodiment of the present invention, obtained at a magnification of 400x; and FIG. 1B is a diagram showing the Ra (μm), Rz (μm), and RSm (μm) of the surfaces of the mold "AS-2mold" and sample "AS-2" obtained at a magnification of 3000x. [Figure 8] FIG. 1 is a diagram illustrating RSm defined in JIS. [Figure 9] 3A and 3B are diagrams illustrating a Si-based coating according to the embodiment of the present invention. [Figure 10] This figure shows the results of a snow accretion test in which sample "AS-1" and sample "AS-2" were attached to the headlights of an automobile. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the embodiment described below.

[0015] In this embodiment, a mold having a surface (transfer surface) that has been subjected to shot blasting is used, and a predetermined shape of the shot blasted surface is transferred to the surface (transfer surface) of a transfer sheet (transfer receiving body). This transfer sheet is coated with a Si-based coating, and the completed product is subjected to a snow accretion test, which revealed that it has a snow accretion suppression effect. Note that in this specification, snow accretion is also included unless otherwise specified.

[0016] Here, in this embodiment, the transfer process is performed only once, so that the irregularities (peaks and valleys) on the transfer surface of the original mold are transferred to the transfer surface of the sheet (transferred object) in an inverted shape. That is, the surface shape (convex and concave shape of the transfer surface) of the processing object (corresponding to the mold in this case) onto which the particulate media is projected and hit becomes a minutely uneven shape with countless dimple-like depressions formed randomly. Therefore, the surface (transfer surface) of the transfer sheet (transferee) onto which the surface shape is transferred using this mold will have countless dome-shaped (approximately spherical shape that convex upward from the surface) minute projections formed randomly (see Figure 5, etc., described below).

[0017] There were two types of transfer sheets with countless randomly formed dome-shaped micro-projections that were effective in suppressing snow accumulation, differing in specifications such as the shape and size of the dome-shaped projections. More specifically, there were two types of transfer sheet surfaces (transferred surfaces) that were effective, and two types of molds for producing these transfer sheets.One was sample "AS-1," which had a surface (transferred surface) on which large domes (large dimples on the mold side) were primarily formed. The other sample is called "AS-2," and has a surface (transferred surface) formed with a mixture of large and small domes (large and small dimples on the mold side).

[0018] The size (for example, the diameter and width of the dome; for the dimple, the entrance diameter and width) of the large dome of the AS-2 (large dimple on the mold side) is the same as the size of the large dome (large dimple on the mold side) of the AS-1. Furthermore, by projecting (shotting) a mixture of fine particle media of different sizes, it is possible to form a mixture of large and small dimples on the surface of the mold (transfer surface). However, by projecting (shotting) large-sized particulate media first and then projecting (shotting) small-sized particulate media, it is also possible to form a mixture of large and small dimples on the surface (transfer surface) of the mold. Here, sample "AS-1" and sample "AS-2" according to this embodiment correspond to an example of the snow accretion suppression sheet member (or snow accretion suppression member) according to the present invention.

[0019] The mold for molding sample "AS-1" is referred to as "AS-1 mold," and the mold for molding sample "AS-2" is referred to as "AS-2 mold."

[0020] The manufacturing methods for the molds "AS-1mold" and "AS-2mold" are explained below. The mold "AS-1mold" is made by subjecting the surface of a stainless steel plate made of SUS304 to a shot projection process (projection processing) in which Saint-Gobain Zirshot (registered trademark) HDC grain number 600 (median grain size 600-800 μm) media (shot material) together with compressed air of about 1 / several (e.g., 0.5) MPa, to form countless dimple-shaped micro-depressions randomly on the transfer surface.

[0021] The mold "AS-2mold" is made by subjecting the surface of a stainless steel plate made of SUS304 to a projection treatment (projection processing) in which Saint-Gobain Zirshot (registered trademark) HDC grain number 600 (median grain size 600-800μm) media (shot material) together with compressed air at a pressure of about 1 / several (e.g. 0.5) MPa, followed by a shot material projection treatment (projection processing) in which media (shot material) under the trade name "Fuji Random (Carborundum)" grain number C♯1000 (average grain size 11.5±1.0μm) media (shot material) together with compressed air at a pressure of about 1 / several (e.g. 0.5) MPa, thereby randomly forming dimple-shaped micro-depressions and even smaller micro-irregularities on the transfer surface.

[0022] Next, the method of producing sample "AS-1" (or sample "AS-2") (steps 1 to 7) will be described. Here, the work (steps) themselves are the same except for the molds used, so we will explain sample "AS-1" as a representative example.

[0023] As shown in Figure 1(A), in step 1, a mold 1 ("AS-1 mold" or "AS-2 mold") that has been subjected to shot projection processing is set with the surface (transfer surface) 1A with the fine irregularities formed thereon facing upward, and in step 2, as shown in Figure 1(B), an unprocessed transfer sheet (transfer target) 2 is placed on top of the transfer surface 1A of the mold 1. As shown in Figures 1(A) and (B), countless dimple-shaped depressions are formed randomly on the transfer surface 1A, which are formed by the impact of shots during the shot projection process.

[0024] Next, in step 3, as shown in Figure 1(C), the transfer sheet 2 (or mold 1) is heated to a predetermined temperature, and the transfer sheet 2 is pressed uniformly (with uniformly distributed load) at a predetermined pressure against the transfer surface 1A of the mold 1, on which the fine irregularities have been formed, in the direction of arrow A via a pressure plate 3 or the like, thereby transferring the fine irregularities of the transfer surface 1A of the mold 1 to the transfer surface 2A of the transfer sheet (transferee) 2. The minute irregularities on the transfer surface 1A of the mold 1 are transferred onto the transfer surface 2A of this transfer sheet (transfer-receiving body) 2, resulting in countless dome-shaped convex portions being formed randomly. The transfer sheet 2 is a sheet-like member having a predetermined area when viewed from above (in the direction of arrow A) in FIG. 1(C).

[0025] In the next step 4, as shown in Figure 1(D), the transfer sheet (transferred sheet) 4 to which the minute uneven shape of the transfer surface 1A of the mold 1 has been transferred is peeled off from the transfer surface 1A of the mold 1, and in step 5, as shown in Figure 1(E), the transferred sheet 4 is removed and set with the transferred surface 4A facing upward. The minute uneven shape of the transfer surface 1A of the mold 1 is transferred onto the transfer surface 4A of the transferred sheet 4, and countless dome-shaped convex portions are formed randomly.

[0026] In the next step 6, as shown in Fig. 1(F), a Si-based coating is applied to the surface 4A (transferred surface) of the transferred sheet 4, on which the minute unevenness of the transfer surface 1A has been transferred, resulting in countless randomly formed dome-shaped protrusions. Here, a worker manually applies (paints) a liquid Si-based coating agent.

[0027] Then, in step 7, as shown in Figure 1(G), the sheet is left for a predetermined time to obtain a finished product (transferred sheet) 5 having a transfer surface 5A on which the Si-based film coating has been fixed, i.e., sample "AS-1" (or sample "AS-2").

[0028] Figure 2 shows 3D images of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2." Figure 2 shows that tiny dome-shaped convex portions with the highest center of the spherical portion (white in the contour color) are randomly formed on the transferred surface. The color scale (color bar) shown in FIG. 2 and FIG. 3 (described later) indicates that the whiter the color, the higher the height, and the closer to black the lower the height. The 3D image in FIG. 2 was acquired using a LASER MICROSCOPE VK-X3000 manufactured by Keyence Corporation (the same applies to FIG. 3 described later).

[0029] Figure 3 shows 3D images of the surface of the mold "AS-1mold" used to produce (molde) sample "AS-1" and the surface (transfer surface) of the mold "AS-2mold" used to produce (molde) sample "AS-2." Figure 3 shows that tiny dimple-like depressions with low centers (black in the contour color) in the spherical parts are randomly formed on the transfer surface.

[0030] Figure 4 shows the shape data of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2." The surface shape data in Figure 4 was acquired using a LASER MICROSCOPE VK-X3000 manufactured by Keyence Corporation (the same applies to Figure 5, which will be described later). From Figure 4, it can be seen that the surface (transferred surface) of sample "AS-1" is mainly formed with relatively large convex portions, while the surface (transferred surface) of sample "AS-2" is formed with multiple relatively small convex portions that overlap the relatively large convex portions.

[0031] Figure 5 shows the shape data of the surfaces (transfer surfaces) of the molds "AS-1mold" and "AS-2mold." From Figure 5, it can be seen that the surface (transfer surface) of the mold "AS-1mold" is mainly formed with relatively large depressions, while the surface (transfer surface) of the mold "AS-2mold" is formed with multiple relatively small depressions that overlap the relatively large depressions.

[0032] Figure 6 shows SEM images of the surfaces (transferred surfaces) of sample "AS-1" and sample "AS-2." This figure shows that the surface (transferred surface) of sample "AS-1" is mainly formed with relatively large convex portions, while the surface (transferred surface) of sample "AS-2" has multiple relatively small convex portions formed on top of relatively large convex portions.

[0033] Next, Figure 7(A) shows the Ra (μm), Rz (μm), and RSm (μm) of the surfaces of the mold "AS-1mold," mold "AS-2mold," sample "AS-1," and sample "AS-2," observed at a magnification of 400x. Furthermore, Figure 7(B) shows the results of Ra (μm), Rz (μm), and RSm (μm) of the surfaces of the mold "AS-2mold" and sample "AS-2" obtained at an observation magnification of 3000x. Note that Ra is a parameter in the height direction called "arithmetic mean roughness" as defined by JIS, and Rz is a parameter in the height direction called "maximum height." RSm as defined by JIS is explained in Figure 8.

[0034] From FIG. 7(A), it can be seen that the transfer surface (finely textured surface) of the mold "AS-1mold" had an average Ra (μm) of 1.95 μm, with a maximum value of 2.29 μm and a minimum value of 1.46 μm. Furthermore, Rz (μm) was 10.63 μm on average, with a maximum value of 13.02 μm and a minimum value of 8.78 μm. Furthermore, RSm (μm) was 252.09 μm on average, with a maximum value of 421.25 μm and a minimum value of 156.39 μm.

[0035] From FIG. 7(A), for the transfer surface (surface with minute irregularities formed) of the mold "AS-2mold", Ra (μm) was an average value of 1.94 μm, with a maximum value of 2.36 μm and a minimum value of 1.06 μm. Furthermore, Rz (μm) had an average value of 10.84 μm, with a maximum value of 14.08 μm and a minimum value of 6.18 μm. Moreover, RSm (μm) was 221.43 μm on average, with a maximum value of 301.00 μm and a minimum value of 150.65 μm.

[0036] Also, from FIG. 7(A), for the transferred surface (finely textured surface, snow-adhesion suppressing surface) of sample "AS-1", Ra (μm) was an average value of 2.19 μm, with a maximum value of 3.34 μm and a minimum value of 1.41 μm. Furthermore, Rz (μm) had an average value of 11.16 μm, with a maximum value of 14.52 μm and a minimum value of 8.24 μm. Moreover, RSm (μm) was 249.38 μm on average, with a maximum value of 317.60 μm and a minimum value of 152.98 μm.

[0037] From FIG. 7(A), the Ra (μm) of the transferred surface (finely textured surface, snow-adhesion-resistant surface) of sample "AS-2" was an average value of 2.45 μm, with a maximum value of 3.16 μm and a minimum value of 1.62 μm. Furthermore, the average value of Rz (μm) was 14.01 μm, with a maximum value of 18.44 μm and a minimum value of 10.44 μm. Furthermore, RSm (μm) was 259.53 μm on average, with a maximum value of 337.46 μm and a minimum value of 187.48 μm.

[0038] Here, as shown in Figure 7(B), when the surfaces (transfer surfaces) of the mold "AS-1mold" and sample "AS-1" were observed at a magnification of 3000x, it was not possible to calculate RSm, etc. As shown in Figure 8, RSm is the average length of the profile element, and when sample "AS-1" is observed at 3000x magnification, this profile element is 0, so it cannot be calculated. On the other hand, when sample "AS-2" is observed at 3000x magnification, the fine uneven profile elements can be observed. Therefore, since sample "AS-2" has a surface based on sample "AS-1," it can be determined that the Ra, Rz, and RSm of sample "AS-2" observed at 3000x magnification shown in Figure 7(B) are measured values ​​of the minute irregularities formed on the relatively large dome-shaped convexities of sample "AS-1."

[0039] Next, we will explain about Si-based coatings. In this embodiment, the snow accumulation suppression effect is enhanced by the double effect of the uneven surface with countless randomly arranged dome-shaped protrusions and the Si-based coating. Generally, a surface is defined as water-repellent if the contact angle of water is 90° or more. As shown in Figure 9, the water contact angles of samples "AS-1" and "AS-2" before the Si-based coating were 90.2° and 104.0°, respectively, both of which were above 90°. This indicates that the micro-irregularities of samples "AS-1" and "AS-2" before the Si-based coating were water-repellent. The water contact angles of samples "AS-1" and "AS-2" after the Si-based coating were 108.0° and 117.5°, respectively, which is an even larger water contact angle than before the Si-based coating, indicating a more water-repellent surface. The water-repellent properties imparted to the surface of the transfer sheet by the effects of both the uneven surface and the Si-based coating are thought to be one of the factors that contribute to the snow accumulation suppression effect.

[0040] In other words, since the snow accumulation suppression effect cannot be confirmed by simply applying a Si-based coating to a flat surface, the snow accumulation suppression effect is achieved on a surface on which countless dome-shaped micro-protrusions are randomly formed in accordance with this embodiment, and by forming a Si-based coating on top of this, the snow accumulation suppression effect can be further enhanced.

[0041] Figure 10 shows the results of a snow accumulation test in which rectangular samples "AS-1" and "AS-2" were attached to a portion of the front of the left and right headlights of a vehicle, and the vehicle was driven through an actual snowy area. Figure 10 clearly shows that both sample "AS-1" and sample "AS-2" are able to suppress the adhesion of snow and ice compared to areas where they are not attached.

[0042] In this way, according to this embodiment, it is possible to impart a snow accumulation suppression effect that can suppress the adhesion of snow (and ice) to the surface of a transfer sheet (resin sheet) on which countless predetermined dome-shaped protrusions are randomly formed. In other words, according to this embodiment, a snow accumulation suppression sheet-like member can be provided that has a snow accumulation suppression effect by randomly forming countless predetermined dome-shaped micro-protrusions on its surface.

[0043] In addition, the surface (surface of sample "AS-1") that had the snow accumulation suppression effect by forming countless random dome-shaped micro-projections was The surface has a Ra (μm) ranging from a maximum value of 3.34 μm to a minimum value of 1.41 μm, or a Rz (μm) ranging from a maximum value of 14.52 μm to a minimum value of 8.24 μm, or a RSm (μm) ranging from a maximum value of 317.60 μm to a minimum value of 152.98 μm, In addition, the surface can have a water contact angle of 90.2° or more (without Si-based coating) or 108.0° or more (with Si-based coating).

[0044] Furthermore, the surface (surface of sample "AS-2") that had a snow accumulation suppression effect due to the countless randomly formed dome-shaped minute convexities had an Ra (μm) of the surface ranging from a maximum value of 3.16 μm to a minimum value of 1.62 μm, or an Rz (μm) of the surface ranging from a maximum value of 18.44 μm to a minimum value of 10.44 μm, or an RSm (μm) of a surface ranging from a maximum value of 337.46 μm to a minimum value of 187.48 μm, In addition, the water contact angle of the surface can be 104.0° or more (without Si-based coating) or 117.5° or more (with Si-based coating).

[0045] Therefore, when considering both the surface of sample "AS-1" (the surface to be transferred) and the surface of sample "AS-2" (the surface to be transferred), the surfaces that had the snow accumulation suppression effect by forming countless random dome-shaped micro-projections were: The surface has a Ra (μm) ranging from a maximum value of 3.34 μm to a minimum value of 1.41 μm, or a Rz (μm) ranging from a maximum value of 18.44 μm to a minimum value of 8.24 μm, or a RSm (μm) ranging from a maximum value of 337.46 μm to a minimum value of 152.98 μm, In addition, the surface can have a water contact angle of 90° or more (without Si-based coating) or 117.5° or more (with Si-based coating).

[0046] Furthermore, when considering both the mold "AS-1mold" and the mold "AS-2mold," the surface (transfer surface) of the mold used to form the surface of sample "AS-1" with snow accumulation suppression effect and the surface (transfer surface) of sample "AS-2" can be a surface (transfer surface) whose Ra (μm) is in the range of maximum 2.36μm to minimum 1.06μm, or whose Rz (μm) is in the range of maximum 14.08μm to minimum 6.18μm, or whose RSm (μm) is in the range of maximum 421.25μm to minimum 150.65μm.

[0047] In this embodiment, countless dome-shaped minute convex portions are formed randomly by transfer, but the present invention is not limited to this, and they can also be formed by other methods. However, the transfer method using a mold makes it possible to produce a large number of surfaces with snow-reducing properties in a short period of time, which can contribute to improved productivity and reduced product costs.

[0048] In this way, according to this embodiment, it is possible to impart a snow accumulation suppression effect to a transferred surface (a component surface in which the shape (orientation) of the irregularities is inverted relative to the shape of the shot projection surface) formed using a mold having an irregular surface (transfer surface) that has been subjected to shot projection processing, and this can contribute to improving productivity and ultimately reducing the cost of the product.

[0049] In this embodiment, a sheet (0.5 mm thick) made of EVA resin (ethylene-vinyl acetate copolymer, VA content 25%) was used as the transfer sheet. EVA is suitable for this purpose because it has weather resistance for outdoor use, flexibility, shape conformability, and adhesiveness for attachment to curved surfaces such as LED lights. However, the present invention is not limited to this, and can also be applied to transfer sheets (sheet-like members) made of at least one of resin, rubber, and elastomer materials, as well as transfer sheets (sheet-like members) made of other materials (such as metals such as aluminum and copper).

[0050] Here, the Si (silicone) based coating carried out in this embodiment will be described. In this embodiment, a commercially available coating agent called "Smartphone Keeper" was used. Reference URL”https: / / onlineshop.keepergiken.co.jp / product / index?product_id=38” The ingredients of the coating agent are "silicone resin, dimethylpolysiloxane, and others." In addition, various Si-based coatings are generally available, and products other than those described above can also be applied to the present invention as long as they are Si-based coatings, such as those shown in the following reference examples. <Reference example 1> Reference URL: https: / / nissili.co.jp / item / 403 / (from Nissili Co., Ltd.'s website) The coating agent is a silicon-based coating for the food industry, and is used to improve the release properties of molds when making baked goods. <Reference example 2> Reference URL”https: / / prtimes.jp / main / html / rd / p / 000000110.000026046.html” The coating agent in question is a silicon-based coating for automobiles, used to prevent scratches and dirt. The ingredients are "reactive silicon resin compounds, silane compounds, hydrocarbons, and others." The "Smartphone Keeper" used in this embodiment is also a product of KeePer Giken Co., Ltd.

[0051] As mentioned above, Si-based coating agents are used in a wide range of products, including food and automotive applications, but the Si-based coating agent of the present invention is not particularly limited, and any Si-based coating that can be expected to exhibit snow-proofing effects may be used. Specifically, any Si-based coating that has water-repellent properties on its surface can be applied to the present invention.

[0052] The resin transfer sheet according to the present invention can also be produced, for example, as follows. For example, after applying UV-curable resin to the surface of the mold ("AS-1 mold" or "AS-2 mold"), quartz glass is placed on top of it, and the UV-curable resin is sandwiched between the quartz glass and the surface of the mold ("AS-1 mold" or "AS-2 mold") and pressed to a specified pressure. In this state, UV is irradiated onto the UV-curable resin to harden it. As a result, the uneven shape of the surface of the mold ("AS-1 mold" or "AS-2 mold") is transferred to the surface of the UV-curable resin. Then, by removing (demolding) the UV-curable resin from the mold ("AS-1 mold" or "AS-2 mold"), a UV-curable resin with a one-time transferred textured surface is obtained, in which the textured shape (orientation) is the reverse of the textured shape on the surface of the mold ("AS-1 mold" or "AS-2 mold"). The removed UV curable resin is in the form of a sheet, and can be included in the transfer sheet according to the present invention. The resin used for the transfer can be a UV nanoimprint resin such as PAK-0 manufactured by Toyo Gosei Co., Ltd., which is capable of nano-sized fine transfer (see the URL (https: / / www.toyogosei.co.jp / rd / uv-feature.html) for details).

[0053] As described above, according to the present embodiment, a member having a transferred surface (a member surface in which the shape (orientation) of the projections and recesses is inverted relative to the shape of the shot projection surface) formed using a mold having a transfer surface that has been subjected to a predetermined shot projection treatment, i.e., a surface (transferred surface) having countless dome-shaped minute projections arranged randomly, and for example, the Ra (μm) of the surface is in the range of a maximum value of 3.34 μm to a minimum value of 1.41 μm, or the Rz (μm) of the surface is in the range of a maximum value of 18.44 μm to a minimum value of 8.24 μm, or the RSm (μm) is in the range of a maximum value of 337.46 μm to a minimum value of 152.98 μm, Furthermore, the surface can be provided with a snow and ice adhesion inhibitory effect on surfaces with a water contact angle of 90° or more (without Si-based coating) or 117.5° or more (with Si-based coating).

[0054] Incidentally, the transfer sheet of this embodiment is not limited to being applied (such as by sticking) to the surface of an LED lighting device, but can also be applied to products where it is desirable to prevent snow and ice from adhering, such as roofing and wall materials for buildings, window glass, solar panels, various vehicle lighting, glass, mirrors, bodies, traffic lights, various signs such as road signs, and various bulletin boards. That is, the transfer sheet (sheet-like member) according to this embodiment is not particularly limited to any particular application, and can be applied to any product that can be applied (attached) by adhesion or the like.

[0055] As described above, according to this embodiment, a snow accumulation suppression sheet-like member can be provided that has a snow accumulation suppression effect by randomly forming countless dome-shaped micro-protrusions on its surface.

[0056] Here, in this embodiment, the shot projection process (also called fine particle projection process, fine irregularity formation process, micro-dimple process (MD process), etc.) that forms minute irregularities on the surface of the mold can be performed by using a known injection device to inject media (shot material, abrasive particles) such as those described above and collide them with the surface of the part.

[0057] For example, a blasting device can be used as the injection device, and an example of the blasting device is the "PNEUMA BLASTER" (models: SC series, SG series, etc.) manufactured by Fuji Manufacturing Co., Ltd. Also, for example, the device described in JP 2019-25584 A can be used.

[0058] More specifically, as an injection device for injecting the injected particles toward the surface of the component, a known blasting device (blasting processing device) that injects abrasives (fine particles) together with compressed gas (air, argon, nitrogen, etc.) can be used.

[0059] As for blast processing equipment (blast processing devices), various types are commercially available, including suction-type blast processing equipment that uses the negative pressure generated by the injection of compressed gas to inject abrasives, gravity-type blast processing equipment that injects abrasives that have fallen from an abrasive tank, carried on the compressed gas, direct pressure-type blast processing equipment that introduces compressed gas into a tank containing abrasives and combines the abrasive flow from the abrasive tank with the compressed gas flow from a separately provided compressed gas supply source and injects the abrasives, and blower-type blast processing equipment that injects the direct pressure-type compressed gas flow carried on a gas flow generated by a blower unit, all of which can be used to inject the aforementioned injection particles. Alternatively, a water jet can be used, which sprays a shot at high pressure along with a liquid such as water.

[0060] Furthermore, in this embodiment, it has been described that countless dimple-shaped minute recesses are formed randomly on the surface (transfer surface) of the mold by shot projection processing, but it is also possible to form countless minute recesses and projections randomly by subjecting the surface (transfer surface) of the mold to chemical polishing (chemical etching) or plasma treatment (e.g., argon bombardment treatment). However, the present invention is not limited to these, and the minute recesses and projections formed on the surface (transfer surface) of the mold in the present invention can also be formed by at least one of chemical etching, plasma treatment, shot projection processing, etc., or by an appropriate combination of these. For chemical polishing (chemical etching), it is expected that an aqueous solution of, for example, acidic agents such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, or iron (III) chloride may be prepared in any ratio and used.

[0061] The present invention is not limited to the above-described embodiment of the invention, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0062] 1. Mold (transfer body, mold "AS-1mold" or "AS-2mold") 1A Transfer surface (surface with minute irregularities formed by shot projection processing) 2. Transfer sheet (transferred object or sheet-like member on which dome-shaped micro-protrusions are being formed) 2A Transferred surface (surface on which dome-shaped micro-projections are formed) 3 Pressure Plate 4 Transferred sheet (subject, sample "AS-1" or "AS-2") 4A Transferred surface (surface with dome-shaped micro-projections) 5 Finished product (transferred sheet) 5A Transfer surface (with Si-based coating)

Claims

1. It has a surface with countless randomly distributed dome-shaped micro-projections, A snow accretion prevention sheet-like member characterized in that the surface thereof is water-repellent.

2. The Ra (μm) of the surface is in the range of a maximum value of 3.34 μm to a minimum value of 1.41 μm, or the Rz (μm) of the surface is in the range of a maximum value of 18.44 μm to a minimum value of 8.24 μm, or the RSm (μm) of the surface is in the range of a maximum value of 337.46 μm to a minimum value of 152.98 μm, 2. The snow accretion suppression sheet member according to claim 1, wherein the contact angle of water on the surface is 90 degrees or more.

3. 3. The snow accretion suppression sheet member according to claim 1, further comprising a silicon-based coating on the surface.

4. 4. The snow accretion suppression sheet member according to claim 3, wherein the contact angle of water on the surface of the Si-based coating is 108° or more.

5. 3. The snow accretion suppression sheet member according to claim 1, wherein the snow accretion suppression sheet member is made of at least one of a resin material, a rubber material, and an elastomer material.

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