Surface treatment method for improving slipperiness of liquid or viscous liquid, component, and evaluation method

Abstract

To provide a slipperiness improving surface treatment method of liquid or viscous liquid and member which can improve slipperiness of liquid or viscous liquid to a member surface by randomly forming an infinite number of fine irregularities on the surface of the member.SOLUTION: A slipperiness improving surface treatment method of liquid or viscous liquid of a member improves slipperiness of liquid or viscous liquid to a member surface by randomly forming an infinite number of fine irregularities on the surface of the member so that a water contact angle is 65° or less and a Kurtosis value (Pku) is 3 or more. In a slipperiness improving member of liquid or viscous liquid, on the surface of the member where an infinite number of fine irregularities are randomly formed, a water contact angle is 65° or less and a Kurtosis value (Pku) is 3 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a surface modification technology that can improve the slipperiness of liquids or viscous liquids on a component surface by performing a process to randomly form countless minute irregularities on the component surface. [Background technology]

[0002] To date, the present applicants have proposed a technology that can suppress the adhesion of powder by forming countless irregular (random) minute irregularities on the surface of a member that comes into contact with powder (hereinafter also referred to as a powder contact member) through a fine particle projection process (e.g., fine particle peening process), which is a type of shot material projection process in which shot material is projected, as proposed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6416151 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the present applicants have taken various approaches to explore the possibility of applying surface modification technology that involves randomly forming countless micro-convexities and concaves to various fields, such as confirming in various fields the new effects that can be achieved by forming countless micro-convexities and concaves on the surface of a component.In the process, the present inventors have obtained new knowledge that was previously unknown.

[0005] Up until now, the effects that have been known to be achieved by forming multiple (countless) micro recesses include inhibiting the adhesion of powders and sticky substances, and forming countless micro irregularities on the sliding surface to function as oil reservoirs, reducing sliding resistance and suppressing wear, but the effect discovered this time is completely different and cannot be predicted from these.

[0006] The finding is that forming countless (plural) predetermined minute recesses at random on the surface of a member can improve the sliding properties of liquids and viscous liquids on the surface of the member.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a surface treatment method for improving the slipperiness of a liquid or viscous liquid on a surface of a component by randomly forming countless predetermined minute irregularities on the surface of the component, and a component, and also aims to provide an evaluation method for evaluating (determining) whether or not the slipperiness of a surface for a liquid or viscous liquid has been improved. [Means for solving the problem]

[0008] Therefore, the method for improving the lubricity of a liquid or viscous liquid surface of a member according to the present invention is as follows: The contact angle of water 64.9 Countless minute irregularities are randomly formed on the surface of the component so that the kurtosis value (Pku) is greater than 3. The pitch of the minute irregularities is in the range of a minimum of 0.5 μm to a maximum of 20 μm, and the depth of the recesses associated with the pitch is in the range of a minimum of 0.3 μm to a maximum of 2.0 μm. This improves the sliding properties of the liquid or viscous liquid on the surface of the member.

[0009] The member for improving the lubricity of a liquid or viscous liquid according to the present invention comprises: The contact angle of water on the surface of a material with countless randomly formed microscopic irregularities is 64.9 ° or less and the kurtosis value (Pku) is greater than 3 The pitch of the minute irregularities is in the range of a minimum of 0.5 μm to a maximum of 20 μm, and the depth of the recesses associated with the pitch is in the range of a minimum of 0.3 μm to a maximum of 2.0 μm. It is characterized by:

[0011] In the present invention, the minute irregularities may be formed by a projection process in which shot material is projected.

[0012] In the present invention, the member may be made of metal or resin.

[0013] The liquid or viscous liquid according to the present invention is a food, medicine, or pharmaceutical product. or cosmetics Either It can be characterized in that:

[0014] The member for improving the lubricity of liquids or viscous liquids according to the present invention is suitable for use in hoppers, chutes, storage containers, containers for containing liquids, transporting devices, sliding devices, mixing devices, cooking bowls, etc. or cooking utensils Which one? It can be characterized in that it is used for:

[0015] In addition, the method for evaluating the slipperiness of a liquid or viscous liquid of a member according to the present invention is a method for evaluating the contact angle of water on the surface of a member on which numerous minute irregularities are randomly formed. 64.9 ° or less and the kurtosis value (Pku) is greater than 3 and the pitch of the minute irregularities is in the range of a minimum value of 0.5 μm to a maximum value of 20 μm, and the depth of the recesses related to the pitch of the irregularities is in the range of a minimum value of 0.3 μm to a maximum value of 2.0 μm. The present invention is characterized in that it evaluates whether or not a liquid or viscous liquid has slipperiness on the surface based on this. [Effects of the Invention]

[0016] According to the present invention, a surface treatment method for improving the slipperiness of a liquid or viscous liquid and a component can be provided, which can improve the slipperiness of a liquid or viscous liquid on the surface of a component by randomly forming countless predetermined minute irregularities on the surface of the component. Furthermore, a method for evaluating (determining) whether a surface has improved slipperiness for a liquid or viscous liquid can be provided. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing a test to confirm the smoothness of a hair washing conditioner according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing the observation of the difference in the state of adhesion of a hair wash conditioner after a slippage test. [Figure 3] This is a diagram showing a 3D image of the surface of the mirror-finished test piece "SUS304 #700" subjected to the same sliding test, and the surface roughness. [Figure 4](A) is a diagram showing a 3D image of the surface of a test piece subjected to MD treatment 1 in the same sliding test, (B) is a diagram showing a 3D image of the surface of a test piece subjected to MD treatment 2 in the same sliding test, and (C) is a diagram showing a 3D image of the surface of a test piece subjected to MD treatment 3 in the same sliding test. [Figure 5] FIG. 1 is a diagram showing an example of the surface properties (surface shape, unevenness pitch, and recess depth) of the surface of a test piece that has been subjected to the MD treatment 1. [Figure 6] FIG. 10 is a diagram showing an example of the surface properties (surface shape, unevenness pitch, and recess depth) of the surface of a test piece that has been subjected to the MD treatment 2. [Figure 7] FIG. 10 is a diagram showing an example of the surface properties (surface shape, unevenness pitch, and recess depth) of the surface of a test piece that has been subjected to the MD treatment 3. [Figure 8] (A) is a graph showing the results of a test to confirm slipperiness against various liquids or viscous liquids, and (B) is a graph showing the kurtosis value, water contact angle, and slipperiness improvement effect of each test piece, with the kurtosis value (Pku) on the horizontal axis and the water contact angle (°) on the vertical axis. [Figure 9] FIG. 1A is a diagram illustrating the contact angle of water on a surface, and FIG. 1B is a diagram illustrating the kurtosis value (Pku). [Figure 10] FIG. 10 is a diagram showing measurement conditions for the kurtosis value according to the embodiment. [Figure 11] 10 is a cross-sectional SEM image of a single minute recess formed experimentally by one shot of media used in the fine particle peening treatment according to the embodiment of the present invention. [Figure 12] This is an SEM image of a cross section of a recess created by laser processing. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] As described above, the present applicants have been taking various approaches to explore the possibility of applying surface modification technology that involves forming dimple-shaped (depressed, approximately concave spherical) micro-recesses to various fields, such as by confirming the effects of forming countless micro-recesses on the surface of a component in various fields.In the process of such approaches, the present inventors have obtained new knowledge that was not previously known.

[0020] Specifically, in the course of the above-mentioned approach, the inventors applied a commercially available hair-washing conditioner to the surface of a member (test piece) on which numerous micro-irregularities (dimple-shaped micro-depressions) were formed, and then tilted the test piece to a predetermined angle to observe the behavior of the hair-washing conditioner. As a result, they discovered that among members (samples or test pieces) on which numerous micro-depressions of a certain specification were formed on the surface, there were specifications that allowed the hair-washing conditioner to slide off smoothly (specifications with improved slipperiness). This finding is an effect that was not previously known for components having countless randomly formed minute irregularities (minute recesses) on their surfaces, and as mentioned above, it is an effect that could not be predicted from previous knowledge.

[0021] This will be explained in more detail below. Here, a commercially available hair-washing conditioner was applied to the upper surface of a test piece (component) tilted at an angle of about 10° from the horizontal, and the slipperiness and adhesion were confirmed. This state tilted at an angle of about 10° was set as the starting state, and the test piece was tilted further toward the vertical from this starting state, and the behavior of the hair-washing conditioner was observed. As a result, as shown in Figure 1, it was confirmed that the test piece subjected to MD treatment 1 (shown as "MD treatment 1" in the figure) gradually began to slip at an inclination angle of about 30°. In contrast, the mirror-finished test piece (control: labeled "mirror-finished" in the figure) and the test piece subjected to MD treatment 2 (labeled "MD treatment 2" in the figure) did not slip.

[0022] When the test specimens were then tilted to an angle of 90° (vertical), the hair wash conditioner applied to the mirror-finished test specimen and the test specimen with MD treatment 2 also fell off. However, there were differences in the degree of adhesion of the hair wash conditioner to the surfaces of the test specimens.

[0023] Figure 2 shows the difference in the adhesion of the hair wash conditioner after this slippage test. From Figure 2, it can be seen that the surface of the test piece subjected to MD treatment 1, which was held approximately vertically, had less hair-washing conditioner attached to it than the mirror-finished test piece and the test piece subjected to MD treatment 2.

[0024] The "mirror-finish" test piece is a "SUS304 #700" (untreated shot blasting) test piece, and the surface of the SUS304 stainless steel plate material has been polished with a P700 buff, resulting in a plate material (component) with a glossy surface close to that of a mirror. An example of a typical 3D image of the surface is shown in Figure 3.

[0025] The test piece subjected to "MD treatment 1" is an example of a surface treatment (micro-irregularity formation treatment, shot projection treatment, micro-dimple treatment) that forms countless random micro-irregularities on the surface of a stainless steel plate made of SUS304. Specifically, it is a plate (component) that has been subjected to a projection treatment (projection processing) in which shot (projection material) (SiC (silicon carbide) with particle number #1000 (maximum particle diameter 32 μm or less, particle diameter at the 50% point of cumulative height 11.5 ± 1.0 μm) of product name "Fuji Random C (Carborundum)") is projected together with compressed air. Figure 4(A) shows an example of a typical 3D image of a surface with countless random micro-irregularities.

[0026] On the surface of the test piece of "MD processing 1", countless minute irregularities are formed randomly, with the size of the irregularity pitch (diameter of the recess entrance, spacing between protrusions, or spacing between recesses) in the range of about 0.5 to 2.5 μm, taking into account product variations and measurement errors, and the recess depth related to this pitch in the range of about 0.3 to 1.0 μm, taking into account product variations and measurement errors, etc. Figure 5 shows an example of the surface shape of a test piece of "MD processing 1".

[0027] In addition, when indicating a range for the size of the unevenness pitch (spacing between convex parts, width of the entrance to the concave part, width of the opening, and diameter of the opening) and the depth of the concave part, the range between the minimum and maximum values ​​of the unevenness pitch and the depth of the concave part shall be indicated.

[0028] The surface shape data and 3D surface images in this embodiment, including those described below, were acquired using a shape measurement laser microscope VK-X100 manufactured by KEYENCE Corporation.

[0029] The test piece subjected to "MD treatment 2" is an example of a surface treatment (micro-irregularity formation treatment, shot blasting treatment, micro-dimple treatment) that forms countless random micro-irregularities on the surface of a stainless steel plate made of SUS304. Specifically, it is a plate (component) that has been subjected to a blasting treatment (projection processing) in which an abrasive manufactured by Fuji Manufacturing Co., Ltd. (product name "Zirshot HDC", particle number #400 (particle diameter 0.4 to 0.6 mm)) is projected together with compressed air. Figure 4(B) shows an example of a typical 3D image of a surface with countless random micro-irregularities.

[0030] On the surface of the test piece subjected to "MD processing 2", countless minute irregularities are randomly formed, with the irregularity pitch (diameter of the recess entrance, spacing between protrusions, or spacing between recesses) ranging from about 50 to 165 μm, and the recess depth related to this pitch ranging from about 2.0 to 6.0 μm. An example of the surface shape of the test piece subjected to "MD processing 2" is shown in Figure 6.

[0031] The test piece subjected to "MD treatment 3" is an example of a surface treatment (micro-irregularity formation treatment, shot projection treatment, micro-dimple treatment) that forms countless random micro-irregularities on the surface of a stainless steel plate made of SUS304. Specifically, it is a plate (component) that has been subjected to a projection treatment (projection processing) in which shot (projection material) made of SiC (silicon carbide) shot (projection material) of particle number #400 (maximum particle diameter 75 μm or less, particle diameter at the 50% cumulative height point 30.0 ± 2.0 μm) made by Fuji Manufacturing Co., Ltd. is projected together with compressed air. Figure 4(C) shows an example of a typical 3D image of a surface with countless random micro-irregularities.

[0032] On the surface of the test piece subjected to "MD treatment 3", countless minute irregularities are formed randomly, with the size of the irregularity pitch (diameter of the recess entrance, spacing between protrusions, or spacing between recesses) in the range of about 4.0 to 20.0 μm, taking into account product variations and measurement errors, and the recess depth related to these pitches in the range of about 0.4 to 2.0 μm, taking into account product variations and measurement errors, etc. Figure 7 shows an example of the surface shape of a test piece subjected to "MD treatment 3".

[0033] 8(A) shows the results of a test to confirm the slipperiness (adhesion-inhibiting effect) of the surface of each test piece for a commercially available hair-washing conditioner (viscous liquid), a commercially available mayonnaise (viscous liquid), a commercially available vegetable juice (liquid), a commercially available soy milk drink (liquid), and a commercially available liquid chocolate (viscous liquid). This test confirmed that the test pieces with "MD treatment 1" and "MD treatment 3" had slipperiness (adhesion-inhibiting effect) for liquids or viscous liquids.

[0034] The water contact angle (wettability) and kurtosis value (value indicating the sharpness of the unevenness) of the surface of each test piece were also investigated. The water contact angle of the surface of the test piece was measured using a contact angle meter DMo-701 manufactured by Kyowa Interface Science Co., Ltd. The conditions for measuring the kurtosis value are shown in Figure 10. The results are shown in Figure 8(B).

[0035] The water contact angle was measured by washing the test piece (here, a flat plate) with water, blowing air over it to dry it, and then exposing it to the atmosphere for 50 hours, after which the contact angle with water (purified water) was measured.

[0036] The water contact angle is one of the indicators of "wettability" and "hydrophilicity." The smaller the water contact angle, the higher the "wettability" and "hydrophilicity." The larger the water contact angle, the lower the "wettability" and "hydrophilicity" (see Figure 9(A)).

[0037] The water contact angle on the surface of the "mirror-finish" test piece (SUS304 #700) was 71.6°. In addition, the water contact angle on the surface of the test piece of "MD treatment 1" was 64.9°. In addition, the water contact angle on the surface of the test piece of "MD treatment 2" was 94.1°. Furthermore, the water contact angle on the surface of the test piece of "MD treatment 3" was 38.4°.

[0038] The kurtosis value (Pku) of the surface of the test piece of "MD treatment 1" was 4.2. In addition, the kurtosis value (Pku) of the surface of the test piece of "MD treatment 2" was 2.9. In addition, the kurtosis value (Pku) of the surface of the test piece of "MD treatment 3" was 4.17.

[0039] The kurtosis value (Pku) is one of the indices that indicate the sharpness or peakedness of the height distribution (see FIG. 9(B)). Pku=3: The height distribution is normal. Pku>3: Many sharp peaks and valleys on the surface Pku<3: The surface has few sharp peaks and valleys This indicates that... A kurtosis value (Pku) of less than 3 indicates a water-repellent surface, while a value of more than 3 indicates a hydrophilic surface.

[0040] Due to the nature of mirror surfaces, it is difficult to express the sharpness and kurtosis value (Pku). Therefore, in Figure 8(B), the kurtosis value of the surface of the "mirror-finished" test piece (SUS304 #700) was set to Pku = 3, which is a normal distribution.

[0041] From Figure 8(B), the contact angle of water on the surface with micro-roughness is 64.9 If the thickness is 0° C. or less, it is considered that the surface has slip properties (adhesion suppression effect) against liquids or viscous liquids. Furthermore, if the kurtosis value (Pku) of the surface on which minute irregularities are formed is greater than 3, it is believed that the surface has slip properties (adhesion suppression effect) against liquids or viscous liquids. As shown in Figure 8(B), the contact angle of water on the surface with the micro-roughness formed is 64.9 ° or less and the kurtosis value (Pku) is 3.5 or more or 4.0 or more, it is considered that the surface has slip properties (adhesion-inhibiting effect) against higher liquids or viscous liquids.

[0042] As described above, according to the present embodiment, a surface treatment method for improving slipperiness of a liquid or viscous liquid and a component can be provided, which can improve the slipperiness of a liquid or viscous liquid on the surface of a component by randomly forming countless predetermined minute irregularities on the surface of the component. Furthermore, an evaluation method can be provided for evaluating (determining) whether or not a surface has improved slipperiness for a liquid or viscous liquid.

[0043] Furthermore, a surface that can improve (enhance) the slipperiness of a liquid or a viscous liquid is a surface that has countless randomly formed minute irregularities, and the contact angle of water on that surface is ≦ 64.9 °, and the kurtosis value (Pku) is > 3. In addition, when the shape of the minute irregularities is taken into consideration, the irregularity pitch is in the range of 0.5 to 20 μm, the recess depth related to the irregularity pitch is 0.3 to 2.0 μm, and the contact angle of water on the surface is ≦ 64.9 °, and the kurtosis value (Pku) is >3.

[0044] In addition, the surface of a component on which countless minute irregularities are formed randomly, and the pitch of the minute irregularities is in the range of 0.5 to 20 μm, and the depth of the recesses associated with the pitch is 0.3 to 2.0 μm, can also be described as the surface of a component on which countless minute irregularities are formed randomly, and the depth of the recesses associated with the pitch is in the range of 0.3 μm to 2.0 μm, and the pitch is in the range of 0.5 μm to 20 μm.

[0045] Furthermore, in this embodiment, the slipperiness of liquids and viscous liquids on the surface of components can be improved, but the liquids and viscous liquids are not limited to those subjected to the above-mentioned tests. For example, the present invention can be applied to any liquid or viscous liquid, including water, oil, seasonings such as soy sauce, sauce, and ketchup, household products such as shampoo, conditioner, hair styling products, and liquid detergent.

[0046] In this way, according to the present invention, a countless number of minute irregularities are formed randomly on the surface of a member, and the contact angle of water on the surface is ≦ 64.9 It was found that by making the surface roughness of the surface roughness of the material greater than 3° and the kurtosis value (Pku) greater than 3, it is possible to improve (enhance) the slipperiness of the liquid or viscous liquid on the surface of the material. In addition, the contact angle of water on the surface with micro-roughness is 64.9 It was found that if the surface roughness is 0.2° C. or less and the kurtosis value (Pku) is 3.5 or more or 4.0 or more, the surface has slip properties (adhesion suppression effect) against higher liquids or viscous liquids.

[0047] Furthermore, according to the present invention, the contact angle of water on the surface of a member on which numerous randomly formed minute irregularities are formed is 64.9 0° or less and the kurtosis value (Pku) is greater than 3, it is possible to evaluate (determine) whether or not the surface has slipperiness of a liquid or viscous liquid. In addition, the contact angle of water on the surface with micro-roughness is 64.9By evaluating whether the surface has slipperiness (adhesion suppression effect) against liquids or viscous liquids, it is possible to more reliably evaluate (determine) whether the surface has slipperiness (adhesion suppression effect) against liquids or viscous liquids by evaluating whether the surface has slipperiness (adhesion suppression effect) against liquids or viscous liquids or not based on ... Can do.

[0048] Although the present embodiment has been described as forming countless dimple-shaped micro recesses at random by shot projection processing, countless micro recesses and protrusions can also be formed at random by, for example, subjecting the surface of the member to chemical polishing (chemical etching) or plasma processing (e.g., argon bombardment processing). However, the present invention is not limited to this, and the micro recesses according to the present invention can also be formed by at least one of chemical etching, plasma processing, 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 chemicals such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, or iron (III) chloride may be prepared in any ratio and used.

[0049] In addition, forming micro-irregularities (micro-depressions) on the surface of a component also includes forming micro-irregularities (micro-depressions) on the surface of a component by, for example, transfer using a mold having micro-irregularities (micro-depressions) on its surface formed based on (using) chemical etching, plasma treatment, shot projection treatment, etc.

[0050] Furthermore, the effect of improving the slipperiness of liquids and viscous liquids by the micro-irregularity forming process according to this embodiment is thought to be equivalent for stainless steel, for example, regardless of the surface finish specifications of the base material before treatment, such as #400, #700, 2B, etc., and particularly for non-magnetic austenitic stainless steel (SUS303, 304, 316, etc.).The present invention is also applicable to metal materials other than stainless steel (for example, in the case of iron, metals or alloys such as steel (SS400, etc.), aluminum, titanium, etc.).

[0051] The member according to the present invention may be a resin member or a ceramic member, and the material is not particularly limited.

[0052] Furthermore, the member according to the present invention may be in any shape, such as a block, plate, or sheet, and there are no particular limitations on the shape or size.

[0053] Furthermore, the member according to the present invention can be applied to, for example, any member that comes into contact with liquid or viscous liquid, and can be applied to various members including, for example, storage containers, storage containers (e.g., containers such as hoppers), transporting devices (powder placement sections of belt conveyors, etc.), sliding devices (e.g., chutes, etc.), mixing devices, cooking bowls, cooking utensils, etc.

[0054] Furthermore, the member according to the present invention is also useful for machinery and equipment (processing equipment, machine parts, etc.) used when it is desired to suppress the adhesion of residues in fields that handle food, medicines, pharmaceuticals, cosmetics, etc. (for example, fields that process, produce, etc. food, medicines, pharmaceuticals, cosmetics, etc.) Such machinery and equipment (processing equipment, machine parts) are not particularly limited, and the present invention is applicable and useful to all machinery and equipment (processing equipment, machine parts, etc.) that come into contact with liquids or viscous liquids when performing various processes such as storage, processing, transport, sliding, cooking, and measuring, as well as screw conveyors, chutes, frying pans, pots, and other containers including hoppers, measuring cups, shutters, transport conveyors, transport containers, transport buckets, etc.

[0055] Therefore, the liquid or viscous liquid according to the present invention can be characterized as a food, drug, medicine, or cosmetic.

[0056] The member according to the present invention can be characterized by being used for a hopper, a shooter, a storage container, a container for containing food, a transporting device, a sliding device, a mixing device, a cooking bowl, or a cooking device.

[0057] In addition, the micro-roughness forming process (shot projection process, micro-dimple process) according to this embodiment uses a known injection device to inject media (shot material, abrasive particles) with different specifications (material, size, shape, etc.) as described above while adjusting the conditions, and causes them to collide with the surface of the component to be surface treated, thereby obtaining desired treated products (MD processes 1 to 3, etc.) with different surface shapes (surface textures).

[0058] 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.

[0059] 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.

[0060] 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. A water jet can also be used, which sprays a shot at high pressure along with a liquid such as water.

[0061] Here, in the present invention, in order to identify the shape or structure of an uneven surface formed by (or based on) a shot projection process, also known as a micro-roughness forming process, micro-dimple process, or microparticle projection process, a method of identification is used in which countless dimple-shaped micro-roughnesses (micro-concaves and ridge-like convex portions around the concaves, each with its own shape, pitch, and depth) are formed randomly, which is completely different from the geometric and regular uneven shapes formed according to pre-designed drawings using laser processing or the like. That is, instead of using the expression "micro-depressions are formed on the surface by (or based on) the shot projection process," a specific method (expression) such as "countless micro-convex and concave portions (or micro-depressions) are randomly formed on the surface of the component" is used. However, in comparison with prior art, it is conceivable that the above-mentioned identification method (expression) may make it difficult to adopt the uneven surface formed by the shot projection process as a distinctive identification method (expression) that distinguishes it from others.

[0062] For this reason, it is conceivable that there will be a situation in which it will be necessary to identify an uneven surface formed by (or based on) a shot material projection process using the identification method (expression) of "forming minute unevenness on the surface by (or based on) a shot material projection process." Therefore, at the time of filing this application, there were circumstances that made it impossible or unrealistic to specify the shape, structure, characteristics, etc. of the minute irregularities formed by the shot projection process, and we will explain below why there are cases where we have no choice but to use the expression "by forming minute irregularities on the surface by (or based on) the shot projection process (taking into account cases such as transfer)."

[0063] In shot projection processing, projected particles (media) are collided with the surface of the workpiece using compressed air at speeds of several tens to over a hundred meters per second, forming irregular, micron-sized, roughly spherical micro-depressions with convex edges over almost the entire surface of the workpiece without causing any significant dimensional change. When the media collides to form the micro-depressions in the shot projection processing, the surrounding area rises in a crater-like manner, forming convex portions (see Figure 11). These raised convex portions are then depressed by collisions with other media, resulting in irregular convex portions of irregular height.

[0064] In contrast, mechanical processes such as laser processing and cutting create regular recesses and do not create convexities because they are removal processes (the formation of recesses does not result in the formation of convexities).For this reason, the height of the convexities around minute recesses in mechanical processes such as laser processing and cutting matches the height of the surface (original material surface) of the workpiece (the component being laser processed) (see Figure 12).

[0065] Furthermore, since the minute irregularities formed by the shot projection process are formed in an infinite number of irregular (random) patterns, the surface texture (shape) formed by the shot projection process differs from the surface shape (texture) formed by processes such as polishing and grinding, which scrape the surface and create scratches (grooves such as streaks).However, when measured using a surface roughness meter, the two end up with similar numerical values, so it is not possible to distinguish between the two based on surface roughness, etc.

[0066] However, the effects obtained by the surface texture (shape) formed by the shot projection process (such as the effect of improving slipperiness against liquids or viscous liquids) are exceptional and cannot be predicted from the surface texture formed by processes such as polishing or grinding, which scratch the surface by scraping it. Furthermore, shot peening, which involves colliding media of the order of several millimeters to impart residual stress and improve the fatigue limit, makes it impossible to predict that a surface subjected to shot projection treatment would have an effect of improving the slipperiness of a surface against liquids or viscous liquids.

[0067] In this way, the minute irregularities formed by the shot projection process are formed in an infinite number of irregular (random) patterns, the shapes of the minute concaves and convexities around them are irregular, and in light of this irregularity being the source of the effects achieved by the present invention, it is not possible to specify the surface formed by the shot projection process other than by using the expression "formed by (or based on) the shot projection process" as a term for specifying the surface texture (shape) formed by the shot projection process. As described above, at the time of filing this application, it is impossible or impractical to specify the shape, structure, characteristics, etc. of the minute irregularities formed by the shot projection process.

[0068] 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.

Claims

1. A surface treatment method for improving the slipperiness of a liquid or viscous liquid on a member, characterized in that a countless number of minute irregularities are randomly formed on the surface of the member so that the water contact angle is 64.9° or less and the kurtosis value (Pku) is greater than 3, and the irregularity pitch of the minute irregularities is in the range of a minimum of 0.5 μm to a maximum of 20 μm, and the depth of the recesses related to the irregularity pitch is in the range of a minimum of 0.3 μm to a maximum of 2.0 μm, thereby improving the slipperiness of the liquid or viscous liquid on the surface of the member.

2. 2. The method for surface treatment of a member to improve lubricity of a liquid or viscous liquid according to claim 1, wherein the minute irregularities are formed by a projection treatment in which shot material is projected.

3. 3. The method for surface treatment of a member to improve lubricity against liquid or viscous liquid according to claim 1 or 2, wherein the member is made of metal or resin.

4. A member for improving the slipperiness of liquids or viscous liquids, characterized in that the surface of the member has a water contact angle of 64.9° or less, a Kurtosis value (Pku) of greater than 3, and the pitch of the minute irregularities is in the range of a minimum of 0.5 μm to a maximum of 20 μm, and the depth of the recesses related to the pitch is in the range of a minimum of 0.3 μm to a maximum of 2.0 μm.

5. 5. The member for improving the lubricity of liquids or viscous liquids according to claim 4, wherein the minute irregularities are formed by a projection process in which shot material is projected.

6. 6. The member for improving the lubricity of liquids or viscous liquids according to claim 4 or 5, characterized in that it is made of metal or resin.

7. 7. The member for improving the lubricity of liquids or viscous liquids according to any one of claims 4 to 6, wherein the liquid or viscous liquid is any one of food, medicine, pharmaceuticals, and cosmetics.

8. The member for improving the slipperiness of liquids or viscous liquids according to any one of claims 4 to 7, characterized in that it is used in any of hoppers, chutes, storage containers, containers for containing liquids, transporting devices, sliding devices, mixing devices, cooking bowls, and cooking devices.

9. A method for evaluating the slipperiness of a liquid or viscous liquid on a member, characterized in that the presence or absence of slipperiness of the liquid or viscous liquid on the surface of the member on which countless minute irregularities are randomly formed is evaluated based on the fact that the water contact angle of the surface is 64.9° or less, the Kurtosis value (Pku) is greater than 3, the irregularity pitch of the minute irregularities is in the range of a minimum value of 0.5 μm to a maximum value of 20 μm, and the depth of the recesses related to the irregularity pitch is in the range of a minimum value of 0.3 μm to a maximum value of 2.0 μm.

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