JP2017001000A - Method for forming water-repellent surface and water-repellent article with water-repellent surface formed using the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a water-repellent surface capable of stably achieving high water-repellent property, and a water-repellent article with the water-repellent surface formed using the same method.SOLUTION: A method for forming a water-repellent surface by performing an etching treatment on a base material, wherein a convexoconcave shape is formed on the base material, with a ten point height of roughness profile (Rzjis) of 0.2 to 120 μm, mean spacing (Sm) between ruggedness of 0.5 to 35 μm, and surface roughness in maximum height (Rz) of 0.1 to 40 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water-repellent surface forming method and a water-repellent article having a water-repellent surface formed using the method, and in particular, formed using the water-repellent surface forming method using the etching method and the method. The present invention relates to a water-repellent article having a water-repellent surface.

  Conventionally, in order to prevent problems caused by water adhesion on the exterior of automobiles and other transportation equipment, window glass, roofs of buildings such as houses, mirrors and spectacle lenses, electrical appliances and industrial equipment, etc. A water-repellent film using a fluorine material or the like is applied to the material surface to prevent water droplets from adhering. However, the water repellency cannot be sufficiently increased only by applying the water repellent film on the surface of the substrate. Therefore, conventionally, attempts have been made to improve the water repellency by forming fine irregularities on the surface of the base material and the lotus effect. By forming fine irregularities on the surface of the substrate in advance and applying a water-repellent film on the surface of the substrate further on the fine irregularities, higher water repellency can be realized and the water repellency The film can be firmly adhered to the surface of the substrate by the anchor effect, and the durability is excellent.

  For example, Patent Document 1 discloses a molded article having a super-water-repellent surface for achieving the object of providing a super-water-repellent surface having excellent water repellency and stable water-repellent performance, and a method for producing the same. And a manufacturing method thereof. Specifically, the method for producing a molded article having a super-water-repellent surface in Patent Document 1 performs plasma etching on the surface of a substrate made of a water-repellent resin or a substrate having a water-repellent resin in the uppermost layer, The substrate is characterized in that a concave and convex surface having a predetermined shape is periodically formed at a predetermined pitch on the surface of the substrate (refer to claim 3, paragraph 0009, etc. of Patent Document 1). ).

JP 2006-83244 A

  However, in the method for producing a molded product having a super-water-repellent surface disclosed in Patent Document 1, although a fine uneven surface can be provided on the substrate surface, high water-repellency could not be stably achieved. .

  In view of the above-described problems, the present invention provides a method of forming a water-repellent surface capable of stably realizing high water repellency, and a water-repellent article having a water-repellent surface formed by using the method. For the purpose.

Water-repellent surface forming method according to the present invention: The water-repellent surface forming method according to the present invention is a method of forming a water-repellent surface by subjecting a base material to an etching treatment. An uneven shape having a roughness (Rzjis) of 0.2 μm to 120 μm, an average interval (Sm) of irregularities of the roughness curve of 0.5 μm to 35 μm, and a maximum height roughness (Rz) of 0.1 μm to 40 μm is formed. It is characterized by that.

  In the method for forming a water-repellent surface according to the present invention, the uneven shape has a maximum height difference (Wmax) of waviness of 8 μm to 95 μm, and a maximum height difference (Wmax) of the waviness and a maximum height difference of unevenness. It is preferable that the ratio [Wmax / PV] to (PV) is 10 or more.

  In the method for forming a water-repellent surface according to the present invention, the base material is preferably made of glass, polycarbonate, or acrylic.

  Further, in the method for forming a water-repellent surface according to the present invention, a coating layer formed of two or more coupling agents, a fluorosilanized product and / or a metallohydrogen-modified silicon is formed on the uneven shape of the substrate surface. It is preferable to form a coating layer using an agent.

  Moreover, in the water-repellent surface forming method according to the present invention, it is preferable that at least one of the coupling agents is a fluorine-based silane coupling agent.

Water-repellent article according to the present invention: The water-repellent article according to the present invention includes a water-repellent surface formed using the water-repellent surface forming method.

  The water-repellent surface forming method according to the present invention is simple but can stably achieve high water-repellency. Further, since the water repellent coat can be firmly adhered to the water repellent treated surface by the anchor effect, a water repellent surface having excellent durability can be obtained. Therefore, the water-repellent article according to the present invention can be suitably used for various articles that require water repellency such as drip-proofing of optical lenses and window glass provided in transportation equipment such as automobiles.

It is sectional drawing illustrated in order to demonstrate the water-repellent surface formed in the water-repellent article which concerns on this invention.

  Hereinafter, a water repellent surface forming method according to the present invention and a water repellent article including a water repellent surface formed using the method will be described.

Water-repellent surface forming method according to the present invention: The water-repellent surface forming method according to the present invention is a method of forming a water-repellent surface by subjecting a base material to an etching treatment. An uneven shape having a roughness (Rzjis) of 0.2 μm to 120 μm, an average interval (Sm) of irregularities of the roughness curve of 0.5 μm to 35 μm, and a maximum height roughness (Rz) of 0.1 μm to 40 μm is formed. It is characterized by this.

  In the method for forming a water repellent surface according to the present invention, an etching method is used when forming an uneven shape on the surface of a substrate. Here, the etching method is roughly classified into a dry etching method and a wet etching method, but the present invention can appropriately adopt both of these etching methods. By forming an uneven shape on the surface of the base material using these etching methods, the wettability of the surface of the base material can be adjusted. Below, these dry etching methods and wet etching methods will be briefly described.

  The dry etching method is a method of etching a substrate with a reactive gas (etching gas), active species such as ions, radicals, etc., and irradiating the surface of the substrate with an ion beam to eject atoms to the surface of the substrate. There are sputter etching for etching the substrate, plasma etching for etching the substrate surface by exposing it to plasma, and the like. The dry etching method has an advantage that the undercut is small and excellent in microfabrication as compared with the wet etching method described later.

  The wet etching method is a method of etching using a so-called etching solution. The etching solution used at this time can be appropriately selected according to the material of the substrate surface. When the etching rate is high, the etching solution is sprayed on the substrate surface without being immersed in a tank containing the etching solution. Can also be sprayed. The wet etching method has an advantage that a large area can be processed, mass productivity is high, and processing cost is low as compared with the dry etching method described above.

  In addition, when forming an uneven shape on the surface of the substrate using the etching method, by forming a mask layer on the surface of the substrate in advance, it is possible to precisely form an uneven shape rich in undulations on the surface of the substrate. I can do it. Also, when forming an uneven shape on the substrate surface using the etching method, if a mask layer is not formed on the substrate surface in advance, a complicated shape may be formed on the substrate surface due to differences in etching conditions, etc. It is possible to easily form a large unevenness on the surface of the substrate and a fractal structure in which fine unevenness is formed on the large unevenness. Incidentally, in the water repellent surface forming method according to the present invention, in order to improve the water repellency of the base material surface, the mask layer is removed from the base material surface after etching with the mask layer formed on the base material surface. It is also possible to carry out etching in the state.

  Thus, according to the water repellent surface forming method according to the present invention, a fractal structure suitable for improving water repellency can be easily formed by appropriately setting the etching treatment conditions according to the material of the substrate. (See FIG. 1). According to the generally known Wenzel theory, such an uneven structure increases the substantial surface area of the substrate surface, highlights changes in surface energy associated with wetting, and further improves water repellency. (Refer to the uneven structure formed on the surface of the substrate 2 and the shape of the substrate water-repellent surface 1 in FIG. 1). In addition, according to the commonly known Cassie's theory, such a concave-convex structure is such that water cannot enter the fine concave portion due to capillary phenomenon, and the air in the gap between the adjacent fine convex portions is confined. The area ratio is increased, and the water repellency can be further improved (refer to the gap 11 between the water droplet 10 and the substrate 2 in FIG. 1).

  Further, in the method for forming a water-repellent surface according to the present invention, an etching process is performed, and the ten-point average roughness (Rzjis), the average interval of roughness unevenness (Sm), and the maximum height roughness on the surface of the substrate. By forming all of (Rz) to be within the above-described range, it is possible to stably improve water repellency. Hereinafter, these roughness parameters will be briefly described.

  The ten-point average roughness (Rzjis) is the absolute value of the altitude of the highest peak from the highest peak to the fifth peak from the average line of the extracted part. And the average value of the absolute values of the elevations of the bottom valley from the lowest valley bottom to the fifth (refer to JIS B 0601: 2001). In the method for forming a water-repellent surface according to the present invention, when the ten-point average roughness (Rzjis) is less than 0.2 μm, the uneven shape suitable for improving the water repellency cannot be formed, and the water repellency is sufficiently improved. I can't let you. On the other hand, when the ten-point average roughness (Rzjis) exceeds 120 μm, the unevenness on the surface of the substrate becomes too large, and the water repellency cannot be sufficiently improved.

  The average interval (Sm) of the unevenness of the roughness curve represents the average value of the interval of the mountain-valley cycle determined from the intersection where the roughness curve intersects the average line (see JIS B 0601: 2001). In the method for forming a water repellent surface according to the present invention, when the average interval (Sm) of the unevenness of the roughness curve is less than 0.5 μm, it is not possible to form an uneven shape suitable for improving water repellency. Moreover, when the average interval (Sm) of the unevenness | corrugation of a roughness curve exceeds 35 micrometers, there are few convex parts and recessed parts formed, and it becomes difficult to aim at sufficient improvement in water repellency. In order to improve the water repellency, the number of convex portions and the pitch between the convex portions are important. If the convex portions are arranged closely and the density of existence is not increased, the water repellency cannot be greatly contributed.

  The maximum height roughness (Rz) represents the sum of the maximum value of the peak height of the contour curve and the maximum value of the valley depth in the reference length (see JIS B 0601: 2001). In the method for forming a water-repellent surface according to the present invention, when the maximum height roughness (Rz) is less than 0.1 μm, it is not possible to form an uneven shape suitable for improving water repellency, and the water repellency is sufficiently improved. I can't let you. In addition, when the maximum height roughness (Rz) exceeds 40 μm, the unevenness of the surface of the base material becomes too large, the surface becomes rough, and the transmittance decreases when a glass material is used as the base material. Therefore, it is not preferable.

  Note that, as an indicator of the wettability of the solid surface, the determination is mainly based on the contact angle of water droplets for the sake of simplicity of measurement. In general, the water repellency means that the contact angle of water droplets with respect to a solid surface is 90 ° or more, 110 ° to 150 ° is high water repellency, and more is super water repellency. When the solid surface is flat, the contact angle obtained by applying a water repellent film using a fluorine material or the like is about 100 °, but the water repellency formed by the water repellent surface forming method according to the present invention. The surface can make the contact angle of water droplets with respect to the solid surface 100 ° or more without providing such a water repellent film.

  In the method for forming a water-repellent surface according to the present invention, the substrate surface after the above-described etching treatment has a maximum waviness difference (Wmax) of 8 μm to 95 μm, and the maximum waviness difference (Wmax) of the waviness. It is preferable that the ratio [Wmax / PV] of the height difference between the height and the unevenness (PV) is 10 or more. By satisfying these conditions, the water-repellent article according to the present invention can form an uneven shape more suitable for improving water repellency on the surface of the substrate.

  Here, the maximum height difference (Wmax) of the waviness is the waveform data obtained when the waveform data relating to the waviness is extracted using the filter from the information relating to the unevenness of the sample surface obtained using the three-dimensional surface structure analysis microscope. The maximum value of the height difference (the sum of the maximum peak height and the maximum valley depth of the waveform). In the method for forming a water-repellent surface according to the present invention, when the maximum height difference (Wmax) of waviness is less than 8 μm, the water repellency cannot be sufficiently improved, which is not preferable. Moreover, when the maximum height difference (Wmax) of the undulation exceeds 95 μm, the roughness of the surface of the substrate becomes too large and the aesthetic appearance is impaired. Incidentally, the maximum height difference (Wmax) of the swell was measured using an Olympus laser microscope (OLS4100) as a measuring instrument.

  Moreover, the maximum height difference (PV) of unevenness | corrugation is measured in the state including the roughness which exists in the surface which has a wave | undulation in the maximum height difference of unevenness | corrugation. Therefore, the ratio [(Wmax) / (PV)] between the maximum height difference (Wmax) of the undulation and the maximum height difference (PV) of the unevenness described above indicates a value close to 1, indicating that the unevenness existing on the surface of the waveform. Can be regarded as [(PV) − (Wmax)], and thus represents that the unevenness is fine.

  Moreover, in the water-repellent surface forming method according to the present invention, the substrate described above is preferably made of any one of glass, polycarbonate, and acrylic. By using any one of glass, polycarbonate, and acrylic as the material of the base material, excellent visibility and durability can be obtained, and the base material is suitably used for a cover lens of an automobile lamp body that requires these characteristics. I can do it. In particular, since polycarbonate has a larger surface roughness than glass or acrylic, a fractal structure more suitable for water repellency can be formed on the substrate surface.

  Further, the water repellent surface forming method according to the present invention is a method for forming a coating layer comprising two or more types of coupling agents and fluorosilanized and / or metallohydrogen-modified silicon on an uneven shape formed on a substrate surface. It is preferable to form a coating layer using an agent.

  In the method for forming a water-repellent surface according to the present invention, by applying at least two types of coupling agents, the durability of the water-repellent surface can be dramatically improved and the three-dimensional adhesion to the substrate can be improved. I can do it. Further, in the water repellent surface forming method according to the present invention, a coating layer is formed using the coating layer forming agent described above to form a complete fractal shape, and the water repellent surface having an uneven shape is formed as a super water repellent surface. Can be made.

  In FIG. 1, the coating layer 5 is shown by a two-layer structure of a layer 3 made of a coupling agent and a layer 4 made of a fluorosilane compound and / or a metallohydrogen-modified silicon. The water repellent surface forming method is not limited to the above-described method for applying the coating layer forming agent. For example, the coating layer 5 of the present invention may be applied to the surface of the substrate on which the uneven shape is formed in a state where all the coating layer forming agents are mixed, and each coating layer forming agent is sequentially applied from a plurality of layers. A coating layer may be formed. At this time, the case where a layer is formed using only a part of the coating layer forming agent is also included. Moreover, the order which applies the said coating layer forming agent is not limited at all.

  As the coating layer forming agent used in the present invention, a monofunctional to tetrafunctional fluoroalkylsilane compound or a silanol compound mainly composed of an N-rich bifunctional or higher functional silazane material can be used. The coupling agent of the present invention can improve adhesion by appropriately mixing low molecular weight and large molecular weight among those having a molecular weight of 30 to 280. In addition, water repellency can be further improved by mixing difluoro or fluorosilane-based fluorine-containing materials and / or metallohydrogen-modified silicon as a coating material. The coating layer forming agent of the present invention preferably contains 1% to 3% by weight of the above-described coupling agent in order to improve water repellency. Moreover, you may dilute with silanol compounds, such as tetraethoxysilane and tetramethoxysilane, as a diluent of this coating agent.

  At least one of the coupling agents used in the present invention is preferably a fluorinated silane coupling agent. In the method for forming a water-repellent surface according to the present invention, it is possible to effectively prevent adhesion of dust, snow, etc. by including a fluorinated silane coupling agent in the coating layer. Further, by forming a coating layer containing a fluorine-based silane coupling agent on the surface of the substrate on which the uneven shape of the present invention is formed, the fluorine-based silane coupling agent enters the recess and is exposed to rain and wind for a long time. Even if this is the case, the water-repellent paint does not completely disappear from the substrate surface. Therefore, according to the water repellent surface forming method of the present invention, it is possible to form a water repellent surface that exhibits an excellent water repellent effect over a long period of time.

  Incidentally, in the water-repellent surface forming method according to the present invention, various commonly used coating methods can be applied as a method for forming the coating layer. However, the film thickness of the coating layer after formation is desirably 0.1 μm or less. When the film thickness of the coating layer exceeds 0.1 μm, the minute uneven structure formed in advance on the surface of the base material is buried and the water repellency is lowered. In the water-repellent surface forming method according to the present invention, fine irregularities are formed on the substrate surface in advance before forming the coating layer. By doing so, it is possible to obtain a surface shape with a targeted roughness. The water repellency can be exhibited with good controllability.

Water-repellent article according to the present invention: The water-repellent article according to the present invention includes a water-repellent surface formed by using the above-described water-repellent surface forming method of the present invention. Since the water-repellent article according to the present invention is manufactured by an etching method, a stable production plan can be examined, and when it is mass-produced, it can be provided at a low cost. Therefore, the water-repellent article according to the present invention can be widely used for automobile lamp cover lenses, helmet shields, spectacle lenses, and the like.

  The water-repellent article having a water-repellent surface and the method for forming the water-repellent surface according to the present invention have been described above, but the present invention will be described in more detail below by showing examples of the present invention. In addition, this invention is not limited at all by these examples.

  In Example 1, the surface of the base material was subjected to a sputter etching process, and the contact angle of water droplets with respect to the surface of the base material thereafter was confirmed. Moreover, the sputter etching process conditions performed on the base material surface in Example 1 were set so that the uneven shape formed on the base material surface satisfies the conditions of the present invention. In Example 1, first, a soda glass plate of 90 mm × 90 mm × 2 (t) mm as a base material was put into an arc ion plating apparatus, and the inside of the apparatus was evacuated to a vacuum of 0.1 torr. Preheated at 200 ° C. for 1 minute. Next, argon gas was introduced into the apparatus to 0.3 torr, and etching was performed by bombardment for 120 seconds.

  When the uneven surface was formed on the substrate surface under the above-described sputter etching conditions, the uneven shape formed on the substrate surface in Example 1 had a 10-point average roughness (Rzjis) of 5 μm and an uneven surface roughness. The average spacing (Sm) is 20 μm, the maximum height roughness (Rz) is 20 μm, the maximum difference in waviness (Wmax) is 40 μm, and the ratio between the maximum difference in waviness (Wmax) and the maximum height difference (PV) in unevenness [Wmax / PV] was 40.

Furthermore, in Example 1, after forming an uneven shape on the substrate surface, a coating layer forming agent was applied on the substrate surface under the following conditions. Specifically, 5% of a coupling agent containing polyfunctional silanol and butyl hydrosilazane in the same proportion, 10% of 1-fluorosilane, 10% of 3-fluorosilane, and the remaining coating layer forming agent consisting of a solvent is 120 cc. Sprayed at / m ² . The curing condition of the coating layer forming agent applied to the substrate surface was left at room temperature for 1 hour and then left at 90 ° C. for 1 hour. At this time, the uneven shape formed on the substrate surface of Example 1 has a 10-point average roughness (Rzjis) of 4 μm, an average interval (Sm) of unevenness of the roughness curve of 0.1 μm, and a maximum height roughness. (Rz) was 40 μm, and the maximum difference in waviness (Wmax) was 30 μm.

  The contact angle of water droplets on the surface of the substrate was measured using an automatic contact meter “Model: Alpha” manufactured by Surface Electro Optics Co., Ltd. under conditions of a temperature of 25 ° C. and a relative humidity of 55% RH. . A water drop of distilled water was dropped onto the surface of the glass material serving as a base material on this automatic contact meter, and the contact angle was measured from the image.

In Example 2, the sputter etching process was performed in the same manner as in Example 1, and then the contact angle of water droplets on the substrate surface was confirmed. Moreover, the sputter etching process conditions performed on the base material surface in Example 2 were set so that the uneven shape formed on the base material surface satisfies the conditions of the present invention. In Example 2, first, a 90 mm × 90 mm × 2 (t) mm soda glass plate as a base material was put into an arc ion plating apparatus, and this apparatus was evacuated to a vacuum of 1 × 10 ⁻⁴ torr. And preheating at 200 ° C. for 1 minute. Next, argon gas was introduced into the apparatus to 6 × 10 ⁻³ torr, and etching treatment was performed by bombardment for 20 seconds.

  And in Example 2, the coating layer forming agent was apply | coated on the base-material surface on the same conditions as Example 1. FIG. At this time, the uneven shape formed on the surface of the base material of Example 2 has a 10-point average roughness (Rzjis) of 12 μm, an average interval (Sm) of unevenness of the roughness curve of 0.1 μm, and a maximum height difference of waviness. (Wmax) was 20 μm.

  In Example 2, the same apparatus as in Example 1 was used to measure the contact angle of water droplets on the substrate surface.

  In Example 3, the substrate surface was spray-etched, and the contact angle of water droplets on the substrate surface was confirmed. Moreover, the spray etching process conditions performed on the base material surface in Example 3 were set so that the uneven shape formed on the base material surface satisfies the conditions of the present invention. In Example 3, first, an etching solution in which the surface temperature of a soda glass plate of 90 mm × 90 mm × 2 (t) mm as a base material is set to 200 ° C. and ammonium fluoride, hydrofluoric acid, and aluminum hydroxide are blended is used. Etching was performed under the condition of spray irradiation for 2 minutes.

  And in Example 3, the coating layer forming agent was apply | coated on the base-material surface on the same conditions as Example 1. FIG. At this time, the uneven shape formed on the surface of the base material of Example 3 has a ten-point average roughness (Rzjis) of 0.8 μm, an average interval (Sm) of irregularities of the roughness curve of 5 μm, and a maximum height roughness. (Rz) was 30 μm, the maximum difference in waviness (Wmax) was 60 μm, and the ratio [Wmax / PV] of the maximum difference in waviness (Wmax) to the maximum difference in height (PV) of unevenness was 40.

  In Example 3, the same apparatus as in Example 1 was used to measure the contact angle of water droplets on the substrate surface.

  In Example 4, the substrate surface was spray-etched in the same manner as in Example 3, and then the contact angle of water droplets on the substrate surface was confirmed. Moreover, the spray etching process conditions performed on the base material surface in Example 4 were set so that the uneven shape formed on the base material surface satisfies the conditions of the present invention. In Example 4, first, the surface temperature of a soda glass plate of 90 mm × 90 mm × 2 (t) mm as a base material is set to 200 ° C., and an etching solution in which ammonium fluoride, hydrofluoric acid, and aluminum hydroxide are blended is prepared. Etching was performed under the condition of spray irradiation for 2 minutes.

  And in Example 4, the coating layer forming agent was apply | coated on the base-material surface on the same conditions as Example 1. FIG. At this time, the uneven shape formed on the surface of the base material of Example 4 has a 10-point average roughness (Rzjis) of 8 μm, an average interval (Sm) of irregularities of the roughness curve of 35 μm, and a maximum height roughness (Rz). ) Was 120 μm, the maximum height difference (Wmax) of undulation was 80 μm, and the ratio [Wmax / PV] of the maximum height difference (Wmax) of undulation to the maximum height difference (PV) of unevenness was 31.

  In Example 4, the same apparatus as in Example 1 was used to measure the contact angle of water droplets on the substrate surface.

  The uneven shape formed on the substrate surface (before forming the coating layer) in Examples 1 to 4 described above satisfies all the conditions of the present invention. Table 1 shows these conditions together with the conditions of the comparative sample so as to facilitate comparison.

Comparative example

[Comparative Example 1]
In Comparative Example 1, the sputter etching process was performed in the same manner as in Example 1, and then the contact angle of water droplets on the surface of the substrate was confirmed. Moreover, the sputter etching process conditions performed on the substrate surface in Comparative Example 1 were set so that the uneven shape formed on the substrate surface did not satisfy the conditions of the present invention. In Comparative Example 1, first, a soda glass plate of 90 mm × 90 mm × 2 (t) mm as a base material was put into an arc ion plating apparatus, and the inside of the apparatus was evacuated to a vacuum of 0.1 torr, Preheated at 200 ° C. for 1 minute. Next, argon gas was introduced into the apparatus to 0.5 torr, and etching was performed by bombardment for 20 seconds.

  And in the comparative example 1, the coating layer forming agent was apply | coated on the base-material surface on the same conditions as Example 1. FIG. The uneven shape formed on the surface of the base material of Comparative Example 1 at this time has a ten-point average roughness (Rzjis) of 120 μm, an average interval (Sm) of irregularities of the roughness curve of 0.1 μm, and a maximum height roughness. (Rz) was 65 μm, the maximum difference in waviness (Wmax) was 120 μm, and the ratio [Wmax / PV] of the maximum difference in waviness (Wmax) to the maximum difference in height (PV) of the unevenness was 85.

  In Comparative Example 1, the same apparatus as in Example 1 was used for measuring the contact angle of water droplets on the substrate surface.

[Comparative Example 2]
In Comparative Example 2, the substrate surface was spray-etched in the same manner as in Example 3, and then the contact angle of water droplets on the substrate surface was confirmed. Moreover, the spray etching process conditions performed on the substrate surface in Comparative Example 2 were set so that the uneven shape formed on the substrate surface did not satisfy the conditions of the present invention. In Comparative Example 2, first, the surface temperature of a soda glass plate of 90 mm × 90 mm × 2 (t) mm as a base material is set to 200 ° C., and an etching solution containing ammonium fluoride, hydrofluoric acid, and aluminum hydroxide is mixed. Etching was performed under the condition of spray irradiation for 2 minutes.

  And in the comparative example 2, the coating layer forming agent was apply | coated on the base-material surface on the same conditions as Example 1. FIG. At this time, the uneven shape formed on the surface of the base material of Comparative Example 2 has a ten-point average roughness (Rzjis) of 140 μm, an average interval (Sm) of irregularities of the roughness curve of 0.1 μm, and a maximum height roughness. (Rz) was 80 m, the maximum waviness difference (Wmax) was 105 μm, and the ratio [Wmax / PV] of the waviness maximum height difference (Wmax) to the uneven height difference (PV) was 10.

  In Comparative Example 2, the same apparatus as in Example 1 was used to measure the contact angle of water droplets on the substrate surface.

[Contrast between Example and Comparative Example]
Table 1 below shows the results of comparing the contact angle of water droplets with respect to the substrate surface (before forming the coating layer) on which the uneven shape was formed in Example 1. Moreover, in Table 2 shown below, about Example 1, Example 2, Example 3, Example 4, Comparative Example 1, and Comparative Example 2 in which the roughness conditions of the irregularities formed on the substrate surface are different, respectively. The result which contrasted the contact angle of the water droplet after forming the coating layer on the same conditions with respect to the base-material surface in which the said uneven shape was formed is shown. Hereinafter, Examples 1-4 and Comparative Examples 1 and 2 based on the contents shown in Table 1 on how the roughness condition of the uneven shape of the present invention affects the water repellency of the substrate. We will examine it in comparison.

  In Table 1 and Table 2, the contact angle of the water droplet with respect to the substrate surface on which the uneven shape is formed is 102 ° or more, “◯” indicating a state of good water repellency, and the surface of the substrate on which the uneven shape is formed. A contact angle of water droplets of 100 ° or less was evaluated as “x” indicating a state of poor water repellency. As is apparent from Table 1, Example 1, which satisfies the conditions of the present invention, was excellent in water repellency and was “◯”. Incidentally, in Example 1, the contact angle of water droplets with respect to the surface of the substrate on which the uneven shape was formed (before forming the coating layer) was 104 °.

  Moreover, from Table 2, Examples 1-4 after coating layer formation were all excellent in water repellency, and were "(circle)". On the other hand, Comparative Examples 1 and 2 after the formation of the coating layer were all poor in water repellency and were “x”. Incidentally, the contact angle of the water droplet with respect to the surface of the substrate on which the uneven shape is formed is 120 ° in Example 1, 125 ° in Example 2, 118 ° in Example 3, 128 ° in Example 4, and Comparative Example 1 100 ° and Comparative Example 2 were 100 °. As is apparent from the measurement results of the contact angle of water droplets on the surface of the substrate, Examples 1 to 4 generally have high contact angles and have high water repellency. On the other hand, Comparative Examples 1 and 2 cannot be said to have sufficient water repellency.

  In addition, about Examples 1-4 and Comparative Examples 1 and 2, when the total light transmittance was measured using the Nippon Denshoku Industries Co., Ltd. haze meter NDH2000 (light source: halogen lamp), Examples 1-4 were used. All the transmittances were 90% or more. On the other hand, the transmittances of Comparative Examples 1 and 2 were all 84% or less, and a low transmittance was obtained. From this result, according to the water repellent surface forming method according to the present invention, even if the base material is a glass material, the water repellency is sufficiently improved and the visibility is not lowered.

  According to the water repellent surface forming method according to the present invention, a water repellent surface capable of stably realizing high water repellency can be easily formed. Moreover, the water-repellent surface forming method according to the present invention has high mass productivity and can reduce the manufacturing cost. Therefore, the water-repellent article having the water-repellent surface formed by using the water-repellent surface forming method according to the present invention has excellent water repellency while being inexpensive. Therefore, since the water-repellent article according to the present invention is excellent in drip-proofing, antifouling, snowproofing, etc., it can be suitably used for various articles such as automobile lamp cover lenses, helmet shields, and spectacle lenses.

DESCRIPTION OF SYMBOLS 1 Base material water-repellent surface 2 Base material 3 Layer consisting of coupling agent 4 Layer consisting of fluorosilane compound and / or metallohydrogen modified silicon 5 Coating layer 10 Water droplet 11 Void

Claims (6)

A method of forming a water-repellent surface by performing an etching process on a substrate,
On the surface of the base material, the ten-point average roughness (Rzjis) is 0.2 μm to 120 μm, the average interval (Sm) of the unevenness of the roughness curve is 0.5 μm to 35 μm, and the maximum height roughness (Rz) is 0.00. A method for forming a water-repellent surface, comprising forming an uneven shape having a size of 1 to 40 μm.   The uneven shape has a undulation maximum height difference (Wmax) of 8 μm to 95 μm, and a ratio [Wmax / PV] of the undulation maximum height difference (Wmax) to the undulation maximum height difference (PV) is 10. The method for forming a water repellent surface according to claim 1, wherein the water repellent surface is formed as described above.   The water repellent surface forming method according to claim 1, wherein the base material is made of any one of glass, polycarbonate, and acrylic.   The coating layer is formed using a coating layer forming agent comprising two or more types of coupling agents and fluorosilanized products and / or metallohydrogen-modified silicon on the uneven shape of the substrate surface. The method for forming a water repellent surface according to claim 3.   The method for forming a water repellent surface according to claim 4, wherein at least one of the coupling agents is a fluorine-based silane coupling agent.   A water-repellent article comprising a water-repellent surface formed by using the water-repellent surface forming method according to claim 1.

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