Surface structure with friction anisotropy, and structure and sliding device using the same

Abstract

A structure having a surface structure capable of controlling friction anisotropy and a sliding device utilizing the structure are provided. [Solution] The structure 1 comprises a surface 2 and a structural substance 6 defined by the surface 2, wherein the surface 2 forms a surface structure 4 including a reference surface 3 and a plurality of surface structure elements 4a, the surface structure elements 4a having a convex structure formed on the reference surface 3 and having an inclined structure 4ap inclined relative to the reference surface 3, the inclined structure 4ap including an inclined rising surface portion 4as and a descending portion 4ad descending from an apex 4at of the inclined rising surface portion to the reference surface 3, the gradient of the inclined rising surface portion 4as being equal to or less than the gradient formed by the apex 4at and the vertical direction from the apex 4at toward the reference surface 3, and the gradient of the descending portion 4ad being greater than the gradient of the inclined rising surface portion 4as.

Description

[Technical Field]

[0001] The present invention relates to a surface structure having friction anisotropy, and a structure and a sliding device utilizing the surface structure. [Background technology]

[0002] Many reports have been published on highly lubricated and highly frictional surfaces with controlled friction. Patent Document 1 describes a steel sheet for drawing with surface friction anisotropy, in which the direction of the surface roughness pattern of the steel sheet is controlled to impart anisotropy to the surface properties of the steel sheet, thereby improving processability such as drawing and bending. Patent Document 2 describes a twill fabric in which wool yarn is used for at least one of the warp and weft yarns, and the friction anisotropy of the wool yarn is improved so that the wool yarn does not felt and shrink when washed.

[0003] Patent Document 3 describes a press molding die that has a convex molding surface and a convex portion with a shoulder that slides and presses against the material, and at least a portion of the shoulder has a high-friction surface that has a friction coefficient greater than that of its surroundings and has friction anisotropy, where the friction coefficient varies depending on the direction, thereby achieving a longer life, stabilizing molding quality, etc. Patent Document 4 describes work gloves that have inner and outer surfaces finished with a fish scale texture, improving dexterity, making them easier to put on, and reducing the frequency of breakage during use.

[0004] Non-Patent Document 1 describes that friction control between the belt and pulley is achieved by applying surface texturing to the pulley surfaces of the belts and pulleys that make up the continuously variable transmission of transportation equipment, thereby imparting friction anisotropy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 1-107904 [Patent Document 2] Japanese Patent Application Publication No. 5-339842 [Patent Document 3] Japanese Patent Application Publication No. 2021-146365 [Patent Document 4] Patent No. 6181857 [Non-patent literature]

[0006] [Non-Patent Document 1] "Study on the emergence of anisotropic friction on textured surfaces under boundary lubrication" Proceedings of the 56th Kanto Student Association Graduation Research Presentation Lecture [March 16, 2017, Tokyo] Summary of the Invention [Problem to be solved by the invention]

[0007] However, there have been few reports on controlling the direction in which frictional force is desired to be exerted, and no structures or mechanisms capable of controlling frictional anisotropy have been disclosed. Therefore, it has been difficult to design a surface structure capable of controlling frictional anisotropy as intended, and as a result, it has been difficult to fabricate such a surface structure. The object of the present invention is to solve the above-mentioned problems and to provide a structure having a surface structure capable of controlling frictional anisotropy, and a sliding device using such a structure. [Means for solving the problem]

[0008] The present invention, which solves the above problems, is as follows. [1] A structure having a surface and a structural substance defined by the surface, wherein the surface forms a surface structure including a reference surface and a plurality of surface structure elements, the surface structure elements having a convex structure formed on the reference surface and having an inclined structure inclined relative to the reference surface, the inclined structure including an inclined rising surface portion and a descending portion descending from the top of the inclined rising surface portion to the reference surface, the gradient of the inclined rising surface portion being equal to or less than the gradient formed by the reference surface and the vertical direction from the top toward the reference surface, and the gradient of the descending portion being greater than the gradient of the inclined rising surface portion. [2] The structure according to [1], wherein the height difference based on the convex structure is in the range of micrometer to millimeter size. The height difference based on the convex structure means the difference in distance between the reference surface and the top of the convex structure. [3] The structure according to [1] or [2], wherein the area of ​​the inclined rising surface portion is larger than the area formed by the descending portion. [4] A structure comprising a surface and a structure substance defined by the surface, wherein the surface forms a surface structure including a reference surface and a plurality of surface structure elements, and has a concave structure formed in the structure substance below the reference surface and having an inclined structure relative to the reference surface, and the inclined structure includes a downward portion descending from the reference surface. [5] The structure according to [4], wherein the height difference of the recessed structure is on the order of micrometers. The height difference based on the recessed structure means the difference in distance between the reference surface and the bottom of the recessed structure, that is, the depth. [6] The structure according to any one of [1] to [3], wherein the structure has friction anisotropy due to the gradient of the friction coefficient provided by the gradient structure and the control of the friction direction by the directionality of the convex structure. [7] The structure according to [4] or [5], which has friction anisotropy due to the gradient of the friction coefficient provided by the gradient structure and the control of the friction direction by the directionality of the recessed structure. [8] A sliding device including the structure according to any one of [1] to [7]. [9] [8] A sliding method using the sliding device described in [8]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a surface structure capable of controlling friction anisotropy and a sliding device equipped with the surface structure. [Brief explanation of the drawings]

[0010] [Figure 1] 1A shows an external view of a structure, FIG. 1B shows an external view of the surface structure of the structure, and FIG. 1C shows a schematic diagram of an example of a surface structure element (scale replica), according to one embodiment of the present invention. [Figure 2] (a) Schematic diagram of two adjacent scale replicas, (b) perspective view of the scale replicas, and (c) image of the surface structure including the scale replicas. [Figure 3] Figures showing (a1) the static friction coefficient in air, (a2) the static friction coefficient in water, and (b) the device for measuring the static (dynamic) friction coefficient for a surface structure including a scale replica in the head-to-tail direction. [Figure 4] (a) A schematic diagram showing the dimensions of an example of a surface structure element (scale model), (b) a schematic diagram of the scale model, and (c) a perspective view of the scale model. [Figure 5] (a) Dynamic friction coefficient in air and (b) dynamic friction coefficient in water, from head to tail, for surface structures including scale models with different scale heights. [Figure 6] 10A shows an image of a portion of a surface structure including a scale model, and FIG. 10B shows an image of the surface structure of FIG. 10A including BB', which gives a BB' cross section. [Figure 7] 1A to 1C are diagrams each showing a schematic representation of a portion of a structure including a mountain-shaped model under conditions 1-1, 1-2, and 1-3, respectively, with respect to the design parameters of the mountain-shaped model. [Figure 8] 10A to 10D are diagrams each showing a schematic representation of a portion of a structure including a mountain-shaped model under conditions (a) 2-1, (b) 2-2, (c) 3-1, and (d) 3-2, respectively, with respect to the design parameters of the mountain-shaped model. [Figure 9] Regarding the design parameters of the mountain-shaped model, (a) condition 4-1, (b) part of a structure including the mountain-shaped model under condition 4-2, (c) a diagram showing the relationship between low and high friction and the ease and difficulty of movement of the frictioned material. [Figure 10] FIG. 10 is a diagram showing (a) the forward and reverse directions in a mountain-shaped model, (b) the static friction coefficients under conditions 1-1 to 4-2, and (c) the device for measuring the static friction coefficients. [Figure 11]10A to 10E are diagrams showing the dimensions and arrangement of a triangular pyramid model 34a in (a) pattern A, (b) pattern B, (c) pattern C, (d) pattern D, and (e) pattern A, respectively, for a triangular pyramid model. [Figure 12] 10A is a diagram showing an image of a triangular pyramid model 34a, FIG. 10B is an image of a triangular pyramid model 34b, and FIG. 10C is a diagram showing the haze values ​​of patterns A and B in the triangular pyramid model 34a. [Figure 13] FIG. 10 is a diagram showing the static friction coefficients in air and water for patterns A to D using triangular pyramid model 34a or 34b. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be made without departing from the scope of the invention.

[0012] The friction of a surface is controlled by the material and structure of the surface. The coefficient of friction, which indicates the frictional properties, is improved by using rubber or viscoelastic materials. Also, a friction mechanism is imparted by fine concave and / or convex structures. By controlling the friction of a surface, the surface can be made highly lubricated or highly frictional. For example, climbing skins for cross-country skiing are provided by utilizing the directionality of the nap, and the length of the feathers planted on one side of the core material is on the millimeter scale.

[0013] As shown in Fig. 1(a), a structure 1 according to an embodiment of the present invention is a sheet-like molded product made of a transparent elastomer. The molded product is wrapped around a rod 10. As shown in Fig. 1(b), a surface 5 of the structure 1 includes a reference surface 3 and surface structure elements (scale replicas) 4a, forming a surface structure 4.

[0014] The structure 1 has a surface 5 and a structure substance 6 (not shown, for example, the structure substance 6A in FIG. 7(a)) defined by the surface 5, and the surface 5 includes a reference surface 3 and a plurality of surface structure elements 4a formed on the reference surface 3. The surface structure elements 4a have a substantially fan-like shape when viewed perpendicularly to the reference surface 3. When viewed from the A direction, as shown in FIG. 1(c), the thickness of the arc portion of the substantially fan-like shape is t, and the structure has an inclined structure 4ap that is inclined with respect to the reference surface 3, resulting in a convex structure with respect to the reference surface 3. When the structure 1 is, for example, sheet-shaped, the structure 1 has two surfaces, one surface 5 having the surface structure elements 4a, and the other surface 6 (not shown, for example, the surface 1A7 in FIG. 7(a)) forming a bottom surface that does not have such surface structure elements.

[0015] Since a plurality of surface structure elements 4a of the same shape are uniformly formed on the reference surface 3, the surface structure 4 has a structure in which a plurality of surface structure elements 4a are uniformly formed. However, such a structure is just one example of a surface structure, and preferably, the inclined structure 4ap of the surface structure elements 4a imparts a gradient to the friction coefficient of the surface 5, and the directionality of the convex structure controls the friction direction of the surface 5. In this case, the surface structure 4 may have a portion (mainly the reference surface 3) that does not have a surface structure element 4a. Furthermore, the plurality of surface structure elements 4a may include a surface structure element different from the surface structure element 4a.

[0016] From the viewpoint of providing a gradient in the coefficient of friction of the surface 5, the inclined structure 4ap, as shown in FIG. 1(c), includes an inclined rising surface portion 4as that slopes from the reference surface 3 and a descending portion 4ad that descends from the apex 4at of the inclined rising surface portion 4as to the reference surface 3. The gradient of the inclined rising surface portion 4as is equal to or less than the gradient formed by the reference surface 3 and the vertical direction from the apex 4at to the reference surface 3, while the gradient of the descending portion 4ad is greater than the gradient of the inclined rising surface portion 4as (the gradient of the inclined rising surface portion 4as is smaller than the gradient of the descending portion 4ad). With such an asymmetrical structure, a gradient is provided in the coefficient of friction generated in the direction from the inclined rising surface portion 4as to the descending portion 4ad and in the direction from the descending portion 4ad to the inclined rising surface portion 4as. Note that in FIG. 1(c), the descending portion 4ad is approximately perpendicular to the reference surface 3, which is mainly due to the consideration of the formability of the descending portion 4ad. From this point of view, the inclination of the downward portion 4ad is preferably an inclination that moves away from the inclined upward surface portion 4as in the vertical direction from the top portion 4at toward the reference surface 3.

[0017] From the viewpoint of providing a gradient to the friction coefficient, it is preferable that the area of ​​the inclined rising surface portion 4as is larger than the area formed by the descending portion 4ad. Furthermore, since friction on the surface 5 can be generated by the convex structure, the direction of friction on the surface 5 can be controlled by the directionality of the convex structure.

[0018] The material forming the surface can be selected as appropriate, but from the viewpoints of moldability and cost of the structure, rubber or thermoplastic elastomer can be used as the material for the structure 1. Furthermore, from the viewpoints of toughness, durability, etc., metal is preferred as the material for the structure. Note that when the surface structure and the structural substance are made of different materials, the selection of the material for the structure described above will be applied to the material for the surface structure. [Example]

[0019] (scale replica) We fabricated a structure with a surface structure 4′ using a thermoplastic elastomer as a raw material, including scale replicas 4a′ as surface structural elements. Figure 2(a) shows two adjacent scale replicas 4a′, each with a head 4a′a, a tail 4a′b, and a sloped structure 4a′p. The scale replicas 4a′ each measure 600 μm from the head 4a′a to the tail 4a′b. Figure 2(b) shows an image of a scale replica 4a′ with a thickness t of 30 to 100 μm, and Figure 2(c) shows an image of multiple scale replicas 4a′ combined to form the surface structure 4′. The tail 4a′b of the sloped structure 4a′p is arched, and the arc (curved portion) that does not contact the reference surface 3 forms the apex 4a′t of the sloped upright surface. The surface structure 4′ resembles a tile-like arrangement of circular fish scales (scale replicas 4a′). Therefore, the surface structure 4′ can be said to utilize biomimetics. In addition, a reference scale of 1 mm is also shown in FIG.

[0020] Figure 3(a1) shows the static friction coefficients for the surface structure 4' in the head-to-tail direction (see Figure 4(b)) and tail-to-head direction in air, measured using the measurement device 50 shown in Figure 3(b) when the thickness t (height: hight) is 30 to 100 μm. The tail-to-head direction is the exact opposite direction, rotated 180° from the head-to-tail direction. Figure 3(a2) shows the static friction coefficients measured in water instead of air. The static friction coefficients in air were head-to-tail / tail-to-head = 0.421 / 0.489 = 0.86, and in water, head-to-tail / tail-to-head = 0.386 / 0.448 = 0.86. The static friction coefficient in the head-to-tail direction was small both in air and underwater. This indicates that the surface structure 4' has friction anisotropy in both air and underwater.

[0021] (Scale model) Using thermoplastic elastomer as the raw material, we fabricated a structure with a surface structure of a scale model 4b composed of scale replicas 4a'. Figure 4(b) shows the scale model 4b composed of the scale replicas 4a'. The shape of the scale replica 4a', including its preferred dimensional relationship, is as shown in Figure 4(a). Two ellipses 5a' with a minor axis a to major axis b ratio of 1:1.3 are arranged side by side in the minor axis direction and overlapped in the minor axis direction, with a certain overlapping portion removed. As mentioned above, the dimension c from the head 4a'a to the tail 4a'b is 600 μm.

[0022] Figure 5(a) shows the static friction coefficient in air measured in the same manner as Figure 3(a1) for a scale model 4b composed of scales 4a' in Figure 4(a) with dimensions c of 50 μm, 150 μm, 200 μm, 300 μm, 400 μm, 500 μm, and 1000 μm. For all dimensions c other than 50 μm, the static friction coefficient in the head-to-tail direction was small for dimensions other than 50 μm. For example, when dimension c was 400 μm, the static friction coefficient in the head-to-tail direction / static friction coefficient in the tail-to-head direction = 0.11 / 0.16 = 0.69. This indicates that the surface structure 4' has friction anisotropy.

[0023] Figure 5(b) shows the static friction coefficient measured in water instead of air. The static friction coefficient in the head-to-tail direction was smaller except for when the dimension c was 400 μm, where the values ​​were almost the same. For example, when the dimension c was 300 μm, the static friction coefficient in the head-to-tail direction / the static friction coefficient in the tail-to-head direction was 0.15 / 0.25=0.60. This shows that the surface structure 4' formed by the scale model 4b has friction anisotropy both in air and in water. The measurement conditions for the measurement device 50 were: load: 30 g, measurement distance (50a): 3 cm, and contact: φ3 mm iron ball contact.

[0024] In addition, the friction anisotropy tended to be larger in water than in air (for example, when hight was about 200 to 350 μm). This can be presumed to be because water easily flows up the inclined rising surface portion 4as, improving water drainage. Note that the thickness t, minor axis a, major axis b, and dimension c are examples and are not limited to these.

[0025] The surface structure 14 shown in Figures 6(a) and 6(b) includes approximately fan-shaped scale replicas 14a, 14b, 14c, and 14d. The profile shown in Figure 6(c) is the profile of the cross section BB' in Figure 6(b), and the convex structure formed by the scale replicas 14a, 14b, 14c, and 14d is represented by the curve C1. The profile was measured using the cross-section measurement function of a white light confocal laser microscope VK-X3000 manufactured by Keyence Corporation.

[0026] On BB' giving the BB' cross section, measurement position "1" included in scale replica 14a, measurement position "2" included in scale replica 14b, measurement position "3" included in scale replica 14c, and measurement position "4" included in scale replica 14d were taken. In addition, measurement position "1a" was taken between measurement position "1" and measurement position "2", measurement position "2a" between measurement position "2" and measurement position "3", measurement position "3a" between measurement position "3" and measurement position "4", and measurement position "4a" was taken between measurement position "4" and end point B'.

[0027] The measured value at measurement position "1" is shown as "1" on curve C1. The same applies to measurement positions "2," "3," "4," "1a," "2a," "3a," and "4a." The horizontal axis of the profile indicates the measurement position in the direction of the reference surface including scale replicas 14a to 14d. The vertical axis of the profile indicates the dimension from the bottom surface (the other surface) to the surface (one surface). In other words, the position of the bottom surface was 0.00 μm, and the dimension from the bottom surface to the reference surface was approximately 80 μm to approximately 20 μm.

[0028] The convex structure formed by scale replicas 14a, 14b, 14c, and 14d was such that measurement positions "1," "2," "3," and "4" corresponded to the apex of the convex structure, and measurement positions "1a," "2a," "3a," and "4a" corresponded to the reference surface, forming a gentle slope connecting the apex of adjacent convex structures to the reference surface. The dimensions at measurement positions "1a" to "4a" were the thickness (height, t) of scale replicas 14a to 14d. That is, the dimension of 280.06 μm at measurement position "1a" was the thickness of scale replica 14a, the dimension of 284.28 μm at measurement position "2a" was the thickness of scale replica 14b, the dimension of 276.10 μm at measurement position "3a" was the thickness of scale replica 14c, and the dimension of 261.46 μm at measurement position "4a" was the thickness of scale replica 14d. The height difference, i.e., thickness, varied little depending on the measurement position.

[0029] (Mountain model) Using a thermoplastic elastomer as the raw material, structures were fabricated in which the structure 6A was a rectangular sheet and the surface structure elements were mountain-shaped models. As shown in Table 1, Structure 1A (mountain-shaped slit 1A4: Condition 1-1), Structure 1B (mountain-shaped slit 1B4: Condition 1-2), Structure 1C (mountain-shaped slit 1C4: Condition 1-3), Structure 1D (mountain-shaped slit 1D4: Condition 2-1), Structure 1E (mountain-shaped slit 1E4: Condition 2-2), Structure 1F (mountain-shaped slit 1F4: Condition 3-1), Structure 1G (mountain-shaped slit 1G4: Condition 3-2), Structure 1H (mountain-shaped slit 1H4: Condition 4-1), and Structure 1I (mountain-shaped slit 1I4: Condition 4-2) were fabricated. Units are in mm. (Table 1) JPEG2026043617000002.jpg67157

[0030] Fig. 7(a) shows a portion of structure 1A, Fig. 7(b) shows structure 1B, Fig. 7(c) shows structure 1C, Fig. 8(a) shows structure 1D, Fig. 8(b) shows structure 1E, Fig. 8(c) shows structure 1F, Fig. 8(d) shows structure 1G, Fig. 9(a) shows structure 1H, and Fig. 9(b) shows structure 1I. The portions are perspective views including one corner of a rectangular sheet.

[0031] In Table 1, "direction" being "vertical" means that, for example, in FIG. 7(a), multiple identically shaped mountain-shaped slits 1A4 (surface structure elements) are arranged perpendicular to one edge L of the rectangular reference surface, i.e., the positive direction. Therefore, the mountain-shaped slits 1A4 are arranged parallel to each other. The downward portion 1A4ad included in the sloped structure of the mountain-shaped slits 1A4 is perpendicular to the reference surface 1A3, and the same is true for the downward portions included in the sloped structures of the mountain-shaped slits 1B4 to 1I4.

[0032] As is clear from Figure 7(a), the gradient of the inclined rising surface portion 1A4as is equal to or less than the gradient formed by the reference surface 1A3 and the vertical direction from the apex 1A4at toward the reference surface 1A3, and the gradient of the downward portion 1A4ad is greater than the gradient of the inclined rising surface portion 1A4as. As is clear from Figures 7(b) to 9(b), this is also true for the inclined rising surface portion and downward portion included in the slope structure of each of the mountain-shaped slits 1B4 to 1I4. Note that the reference surface, downward portion, inclined rising surface portion, etc. are not shown in Figures 7(b) to 9(b).

[0033] On the other hand, the peak height h was 0.5 mm, the peak width w was 0.5 mm, and the peak density l was 0.5 mm. Also, for example, in Figure 8(c), the slit interval D was 1.0 mm, and the slit interval d was 1.0 mm.

[0034] Furthermore, in Table 1, "Direction" as "upper right" indicates that the mountain-shaped slits 1H4 in Figure 9(a) are arranged in the upper right direction relative to one edge L of the rectangular reference surface, i.e., the positive direction. And "Direction" as "upper left" indicates that the mountain-shaped slits (surface structure elements) in Figure 9(b) are arranged in the upper left direction relative to one edge L of the rectangular reference surface, i.e., the positive direction. Note that because of the orientation of the mountain-shaped slits 1H4 and 1I4, they are shaped as if they are cut off by the edge L, but because their proportion is small, it is estimated that they have almost no effect on the surface structure.

[0035] Comparing the area of ​​the inclined rising surface portion 1A4as and the area formed by the descending portion 1A4ad included in the inclined structure of the mountain-shaped slit 1A4, it is clear that the area of ​​the inclined rising surface portion 1A4as is larger than the area of ​​the descending portion 1A4ad. This was also the case for the area of ​​the inclined rising surface portion and the area formed by the descending portion included in the inclined structure of each of the mountain-shaped slits 1B4 to 1I4.

[0036] Table 2 (Figure 10(b)) summarizes the static friction coefficients of the mountain-shaped model (mountain-shaped slits 1A4 to 1I4: conditions 1-1 to 4-2) measured in the direction shown in Figure 10(a) using the measuring device 50' in Figure 10(c). Table 2 (Figure 10(b)) shows that the static friction coefficient in the forward direction was smaller than the static friction coefficient in the reverse direction under all conditions, both in air and underwater. This means that the mountain-shaped model has friction anisotropy in air and underwater, and can be controlled. The reverse direction is the exact opposite direction, rotated 180° from the forward direction, and the measurement conditions for the measuring device 50' were: load: 30 g, measurement distance: 3 cm, and contact: φ3 mm iron ball contact.

[0037] For example, when comparing the static friction coefficients in the same direction in the same measurement environment (air or water) using the mountain-shaped slits 1A4 to 1C4, the static friction coefficient gradually decreased. This shows that it is possible to control the static friction coefficient itself while exhibiting friction anisotropy. (Table 2) JPEG2026043617000003.jpg80129

[0038] The mountain-shaped model has frictional anisotropy, and the mountain height h of the mountain-shaped slits 1A4 to 1I4 varies in stages from 0.5 mm to 3 mm. Therefore, when a structure having a surface structure with a mountain-shaped model is, for example, a grip, and the grip is held in the hand for use as a grip, a convex structure as small as 0.5 mm is particularly preferable, as it does not cause discomfort to the hand and can exhibit frictional anisotropy.

[0039] The peak height h and peak width w are examples and are not limited to these, but from the viewpoint of eliminating the discomfort felt by the hand due to the convex structure and being able to exhibit friction anisotropy, it is preferable that the peak height h be in the range of micrometer to millimeter size.

[0040] To further explain friction anisotropy based on Figure 9(c), when a force is applied to the friction target material 100, the friction target material 100 moves more easily in the direction where the friction between the friction target material 100 and the surface structure element 24 is low, and moves less easily in the direction where the friction is high.

[0041] (triangular pyramid model)

[0042] Using a thermoplastic elastomer as a raw material, structures were fabricated having surface structures that included triangular pyramid models 34, which were recessed structures with approximately triangular pyramid shapes, as surface structure elements. As shown in Figures 11(a) to 11(d), four types of surface structures were fabricated: Pattern A, Pattern B, Pattern C, and Pattern D. As shown in Figure 12, triangular pyramid models 34a (Figure 11(a)) and triangular pyramid models 34b (Figure 11(b)) were fabricated as triangular pyramid models 34. The triangular pyramid models 34 were formed in a structure substance 36 (not shown) below a reference surface 33 and had a recessed structure with a slope relative to the reference surface 33. The sloped structure included a descending portion 34d that descends from the reference surface 33. From the standpoint of moldability of the descending portion 34d, it is preferable that the descending portion 34d be formed in a direction that maximizes the perpendicular direction from the reference surface 33 toward the structure substance 36. 12(a) and 12(b), the descending portion 34d is formed in the vertical direction from the reference surface 33 toward the structure substrate 36, and in the triangular pyramid model 34a, the depth is approximately 46 μm, and in the triangular pyramid model 34b, the depth is approximately 22 μm. Note that approximately 46 μm and approximately 22 μm are examples of depths, and the present invention is not limited to these.

[0043] For pattern A, if the ratio of the area of ​​the opening of triangular pyramid model 34 on reference surface 33 to the area of ​​reference surface 33 is 1 (100%), the ratios for pattern B, pattern C, and pattern D were 1 / 4 (25%), 1 / 8 (12.5%), and 1 / 16 (6.3%), respectively. Wafer No. 1 (20 mm x 20 mm) was formed using pattern A, pattern B, pattern C, and pattern D in triangular pyramid model 34a, and wafer No. 2 (20 mm x 20 mm) was formed using pattern A, pattern B, pattern C, and pattern D in triangular pyramid model 34b. Note that the above ratios are merely examples and are not limited to these.

[0044] Furthermore, as shown in FIG. 11(e), the triangular pyramid model 34 in pattern A (basic pattern) had a base length of 20 μm and a height of 50 μm. The arrangement of the triangular pyramid models 34 was a repeated arrangement of a pair of triangles in which the perpendicular bisector of the base of the triangle overlapped a pair of opposing sides of an 80 μm-long square, and a pair of triangles in which the line bisecting the height of the triangle overlapped a pair of opposing sides (i.e., four triangular pyramid models). Note that the triangular pyramid model 34 is an example of a concave structure and is not limited to this. Note that the shape and arrangement of the triangular pyramid model described above are merely examples of shapes and arrangements and are not limited to these.

[0045] The degree of cloudiness of wafer No. 1, which had triangular pyramid models 34a as patterns A and B, was as shown in Figure 12(c). Pattern A, which had a larger area ratio of the triangular pyramid models 34a to the reference surface 33, was less transparent and cloudy than pattern B. When the haze values ​​of each were measured, they were 0.63 for pattern A and 0.19 for pattern B, and the haze value for pattern A / the haze value for pattern B = 0.63 / 0.19 = 3.3. For example, if the thermoplastic elastomer is transparent, the balance between the cloudiness of the structure and the static friction coefficient (described later) can be adjusted by changing the area ratio of the triangular pyramid models.

[0046] The static friction coefficients were measured in air and water for wafers with the following patterns: triangular pyramid model 34a (pattern A(1-A)), triangular pyramid model 34a (pattern B(1-B)), triangular pyramid model 34a (pattern C(1-C)), triangular pyramid model 34a (pattern D(1-D)), triangular pyramid model 34a (pattern A(2-A)), triangular pyramid model 34b (pattern B(2-B)), triangular pyramid model 34b (pattern C(1-C)), and triangular pyramid model 34b (pattern D(2-D)). Table 3 summarizes the results of measurements taken using the measurement device 50' shown in Figure 10(c) in the direction shown in Figure 11(e). These results are also shown in Figure 13. The forward direction shown in Figure 11(e) is the direction perpendicular to the apex of the triangle and the reverse direction is the direction rotated 180° from the forward direction. (Table 3) JPEG2026043617000004.jpg76135

[0047] Table 3 (Figure 13) shows that when the same triangular pyramid model and the same pattern were used in air and water, the static friction coefficient in the forward direction was smaller than the static friction coefficient in the reverse direction. This means that the triangular pyramid model has friction anisotropy and can be controlled. This is because the shape of the triangle in the forward direction that generates the static friction coefficient for the triangular pyramid model is different from the shape of the triangle in the reverse direction (asymmetric). Also, for the same triangular pyramid model, the static friction coefficient increased as the ratio of the area of ​​the opening of the triangular pyramid model 34 on the reference surface 33 to the area of ​​the reference surface 33 decreased. This is because the contact area increases as this ratio decreases.

[0048] Furthermore, when comparing triangular pyramid model 34a and triangular pyramid model 34b with the same pattern in air and water, triangular pyramid model 34b tended to have a higher static friction coefficient. It is presumed that the friction generated at shallower depths is influenced by the structure substance. From the above, it can be seen that it is possible to control the static friction coefficient itself while expressing friction anisotropy. Note that the triangular pyramid model is an example of a concave structure, and is not limited to this. [Industrial Applicability]

[0049] Metallic, inorganic, and organic materials can all be used to form the surface structure of this invention. It can also be used in sliding devices, for example, to save energy by controlling friction on the contact surface during automatic robot operation, to improve grip for children and elderly people with weak grip strength, and to change friction anisotropy due to structural deformation induced by environmental changes. [Explanation of symbols]

[0050] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I: Structure 1A4, 1B4, 1C4, 1D4, 1E4, 1F4, 1G4, 1H4, 1I4: Mountain-shaped slits (surface structure elements) 1A7: Bottom 2: Surface 3, 23, 33, 1A3: Reference surface 4, 4´, 14: Surface structure 4a, 4a´, 14a, 14b, 14c, 14d: Scale replicas (surface structure elements) 4b: Scale model 4a´a: Scale replica head 4a´b: Scale replica tail 4ap, 4a´p: inclined structure 4as, 4a's, 1A4as: Inclined rising surface 4at, 4a´t: Top of the inclined rising surface 4ad, 4a´d, 1A4ad, 34d: Downhill section 5: Surface (one side) 5a´: oval 6, 6A, 36: Structure substance 7: The other surface (bottom) 10: Stick 24:Surface structure elements 34, 34a, 34b: Triangular pyramid model (surface structure element) 50, 50´: Measuring device 50a: Measurement distance 100: Frictional material a: Minor axis b: major diameter c: Dimensions of the scale replica C1:Curve d: slit spacing L: One edge of the reference surface h: Mountain height w: mountain width l:Mountain density D: Slit spacing

Claims

1. A structure comprising a surface and a structural substance defined by the surface, wherein the surface forms a surface structure including a reference surface and a plurality of surface structure elements, the surface structure elements having a convex structure formed on the reference surface and having an inclined structure inclined relative to the reference surface, the inclined structure including an inclined rising surface portion and a descending portion descending from an apex of the inclined rising surface portion to the reference surface, the gradient of the inclined rising surface portion being equal to or less than the gradient formed by the reference surface and a vertical direction from the apex toward the reference surface, and the gradient of the descending portion being greater than the gradient of the inclined rising surface portion.

2. The structure according to claim 1 , wherein the height difference based on the convex structure is in the range of micrometer to millimeter.

3. 3. The structure according to claim 1, wherein the area of ​​the inclined rising surface portion is larger than the area of ​​the descending portion.

4. A structure comprising a surface and a structure substance defined by the surface, wherein the surface forms a surface structure including a reference surface and a plurality of surface structure elements, and the structure has a concave structure formed in the structure substance below the reference surface and having an inclined structure relative to the reference surface, and the inclined structure includes a descending portion that descends from the reference surface.

5. The structure according to claim 4 , wherein the height difference of the recessed structure is on the order of micrometers.

6. 3. The structure according to claim 1, wherein the structure has friction anisotropy due to the gradient of the friction coefficient provided by the inclined structure and the control of the friction direction by the directionality of the convex structure.

7. 6. The structure according to claim 4, wherein the structure has friction anisotropy due to the gradient of the friction coefficient provided by the inclined structure and the control of the friction direction by the directionality of the recessed structure.

8. A sliding device comprising the structure according to claim 1 , 2 , 4 or 5 .

9. A sliding method using the sliding device according to claim 8.

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