Cushioning materials and footwear

Abstract

To provide a cushioning material capable of exhibiting shock absorption and repulsion properties in accordance with the running process, and footwear using the same. [Solution] The cushioning material for footwear comprises a three-dimensional structure that is elastically deformable in the compression direction. The three-dimensional structure is formed by juxtaposing and interconnecting a plurality of basic structural elements (19) in the width direction. The basic structural elements (19) include a plurality of polygonal rigid portions (21) and a plurality of flexible portions (23). In a plane-filling pattern in which a plurality of polygonal first elements and a plurality of polygonal second elements are alternately arranged adjacent to each other within a plane, the basic structural elements (19) are formed by replacing the first elements with the polygonal rigid portions (21) and the second elements with the flexible portions (23). The flexible portions (23) are formed by a plurality of deformable deformation struts (23b) that extend radially from the center of gravity of each second element so as to connect the center of gravity of each second element with each vertex of each second element.

Description

[Technical Field]

[0001] The present invention relates to a cushioning material having a three-dimensional structure that has a compression direction, a length direction perpendicular to the compression direction, and a width direction perpendicular to the compression direction and length direction, and that is deformable in the compression direction, and to footwear that uses the cushioning material as a sole. [Background technology]

[0002] Generally, footwear includes an upper for receiving a wearer's foot and a sole to which the upper is fixed and which comes into contact with the ground. In recent years, footwear using shock-absorbing materials in the soles has been developed not only for athletic footwear but also for general footwear such as running shoes, in order to reduce the impact on the wearer's foot when it touches the ground and protect the wearer's foot.

[0003] Foam materials made from expanded resin materials are widely used as cushioning materials for footwear. In recent years, the widespread use of 3D printers has made it possible to form complex three-dimensional structures, leading to the development of soles with lattice and web structures. For example, soles with three-dimensional structures exhibiting high shock absorption have also been developed, as described in Patent Documents 1 and 2. Specifically, the sole for a footwear product disclosed in Patent Document 1 includes a 3D-printed midsole, which is a three-dimensional mesh having a plurality of interconnected unit cells, each having a plurality of struts defining a three-dimensional shape and a plurality of nodes to which one or more struts are connected. Furthermore, the cushioning material used in shoe soles disclosed in Patent Document 2 includes a three-dimensional structure in which unit structures are formed as three-dimensional shapes formed by walls whose outlines are defined by a pair of parallel planes or curved surfaces, and the unit structures are regularly and continuously arranged in at least one direction. Deformed portions that do not correspond to the walls defining the unit structures are locally provided in the buffer region, which is the region of the three-dimensional structure where the unit structures are arranged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-187363 [Patent Document 2] Patent Publication No. 2021-186336 Summary of the Invention [Problem to be solved by the invention]

[0005] Cushioning materials using foam materials formed from the above-mentioned foamed resin materials have high resilience or elasticity but lack shock absorption. Cushioning materials with a three-dimensional structure have high shock absorption but low elasticity. Meanwhile, users of running shoes and the like desire high shock absorption when landing and high resilience when taking off while running. However, conventional soles have not been able to fully meet these demands.

[0006] Therefore, an object of the present invention is to solve the problems in the prior art and to provide a cushioning material that can exhibit shock absorption and resilience in accordance with the running process, and footwear using the same. [Means for solving the problem]

[0007] In view of the above object, the present invention provides, in a first aspect, a cushioning material comprising a three-dimensional structure having a compression direction, a length direction perpendicular to the compression direction, and a width direction perpendicular to the compression direction and the length direction, and being deformable in the compression direction, wherein the three-dimensional structure is formed by juxtaposing a plurality of basic structural elements each extending in the compression direction and the length direction and connecting them to each other in the width direction, the basic structural elements including a plurality of polygonal or polygonal circumscribed circular rigid parts having relatively high rigidity and a plurality of flexible parts having relatively low rigidity, and the plurality of polygonal first elements and the plurality of polygonal second elements are alternately adjacent to each other so that each vertex of the polygonal first element is connected to a vertex of any one of the polygonal second elements, In a plane-filling pattern arranged in a plane extending in the longitudinal direction and the longitudinal direction, the basic structural element is formed by replacing the first element with a rigid part having the polygonal shape or a circumscribed circle shape of the polygonal shape and replacing the second element with a flexible part, the flexible part being composed of a plurality of deformable struts extending radially from the center of gravity of the second element so as to connect the center of gravity of the second element to all of the vertices of the second element, the flexible part being composed of a plurality of deformable struts extending radially from the center of gravity of the second element so as to connect the center of gravity of the second element to all of the vertices of the second element, and the rigid part and the flexible part are configured such that when the basic structural element is compressed in the compression direction, the rigid part moves in one of a clockwise direction and a counterclockwise direction. The rigid portion Rotates around the center of gravity, and the flexible part the plurality of deformed struts clockwise and counterclockwise the center of gravity of the flexible portion To rotate around 、 To provide a cushioning material arranged in such a manner.

[0008] In the above-mentioned cushioning material, when an impact is applied in the compression direction, first, the relatively rigid rigid portion rotates around the center of gravity while the deformed struts of the relatively less rigid flexible portion rotate in the opposite direction to the rigid portion, increasing their density and causing them to collapse, thereby absorbing the impact.After that, as force is transmitted between the rigid portions, the relatively rigid rigid portion is able to exert a greater reaction force against compression while maintaining a certain degree of elasticity.

[0009] In one embodiment of the cushioning material, the rigid portion may be composed of a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element and a plurality of inner struts extending radially from the center of gravity of the polygonal rigid portion to a plurality of vertices.

[0010] In another embodiment of the cushioning material, the rigid portion may be formed by a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element, the outer struts being thicker than the deforming struts.

[0011] In another embodiment of the above-described cushioning material, the rigid portion may be formed by a flat plate having a polygonal shape or a circular shape circumscribing a polygon.

[0012] In the above-mentioned cushioning material, a plurality of the basic structural elements are arranged side by side in the width direction, and the rigid portions within the basic structural elements are each arranged opposite the rigid portions within adjacent basic structural elements in the width direction, and the three-dimensional structure can be constructed by connecting each vertex of the rigid portion within a basic structural element to each vertex of the opposing rigid portion in another adjacent basic structural element in the width direction with connecting struts.

[0013] in this case, the rigid portion includes a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element; A rectangular cell formed by two outer struts connecting adjacent vertices in the opposing rigid parts of two adjacent basic structural elements and two connecting struts connecting the adjacent vertices in the width direction may be reinforced by reinforcing struts extending diagonally.

[0014] In the above-mentioned cushioning material, the three-dimensional structure may be configured such that the basic structural elements are connected in the width direction as if the basic structural elements were swept in the width direction.

[0015] It is preferable that the first element and the second element are configured by a combination of a hexagonal first element and a triangular second element, a combination of a quadrangular first element and a quadrangular second element, or a combination of a triangular first element and a triangular second element.

[0016] Furthermore, it is preferable that the multiple deforming struts of the flexible section are arranged inclined at the same angle in the same direction around the rigid section with respect to an axis connecting the center of gravity of the rigid section to which each deforming strut is connected and the vertex of the rigid section to which the deforming strut is connected.

[0017] In a second aspect, the present invention provides footwear comprising an upper that accommodates the wearer's foot and a sole that is attached below the upper to form the bottom, the sole having the above-mentioned cushioning material.

[0018] The sole may include a first buffer layer made of the buffer material and a second buffer layer made of an elastic material, the first buffer layer and the second buffer layer being laminated together. In this case, the elastic material may be, for example, a foamed resin material, a rubber material, or an elastomer material.

[0019] In the above-mentioned footwear, it is preferable that the multiple deforming struts of the flexible part of the cushioning material are arranged tilted at the same angle in the same direction around the rigid part with respect to an axis connecting the center of gravity of the rigid part to which each deforming strut is connected and the vertex of the rigid part to which the deforming strut is connected.

[0020] The deformable struts of the flexible portion are arranged to deform the rigid portion when the cushioning material is compressed. Progress It is more preferable that the rigid portion is connected to the apex of the rigid portion of the buffer material at an angle relative to an axis connecting the center of gravity of the rigid portion and the apex, in a direction moving diagonally downward in the row direction. [Effects of the Invention]

[0021] According to the present invention, the rigid and flexible portions of the cushioning material first rotate in opposite directions, increasing their density as they collapse, thereby absorbing impact, and then the rigid portion can provide a greater reaction force against compression while maintaining a certain degree of elasticity. Therefore, if this cushioning material is applied to the sole of footwear, it will exhibit shock absorption properties when the foot touches the ground, and will assist the forward propulsion force with the reaction force when the foot pushes off, making it easier to run. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a side view showing an example of the configuration of footwear using a cushioning material according to one embodiment of the present invention in the sole. [Figure 2] FIG. 2 is a schematic diagram showing the two-dimensional structure of the cushioning material used in FIG. 1 when viewed from the side. [Figure 3] 3 is a perspective view of the cushioning material showing a first example of the structure of the cushioning material shown in FIG. 2 in the width direction (direction perpendicular to the paper surface). FIG. [Figure 4] 3 is a perspective view of the cushioning material showing a second example of the structure of the cushioning material shown in FIG. 2 in the width direction (direction perpendicular to the paper surface). FIG. [Figure 5] 3 is a perspective view of a cushioning material showing a third example of the structure of the cushioning material shown in FIG. 2 in the width direction (direction perpendicular to the paper surface). FIG. [Figure 6] 3A and 3B are explanatory diagrams for explaining the deformation of the cushioning material shown in FIG. 2, where (a) shows the state of the cushioning material when no force is acting in the compression direction (vertical direction), and (b) shows the state of the cushioning material when a compressive force is acting in the compression direction. [Figure 7] 1A to 1C are explanatory diagrams showing a procedure for designing a two-dimensional structure of a cushioning material. [Figure 8] 1A to 1C are explanatory diagrams showing a procedure for designing a two-dimensional structure of a cushioning material. [Figure 9] 10 is an explanatory diagram illustrating an arrangement in which a rigid portion and a flexible portion are rotated and deformed in order to smoothly compress the cushioning material according to the present invention. FIG. [Figure 10]2A to 2C are explanatory diagrams showing deformation of the two-dimensional structure of the cushioning material according to the first embodiment of the present invention and the behavior of the rigid and flexible parts when compressed. [Figure 11] 10A and 10B are explanatory diagrams showing deformation of the two-dimensional structure of a cushioning material according to a second embodiment of the present invention and the behavior of a rigid portion and a flexible portion when compressed. [Figure 12] 10A and 10B are explanatory diagrams showing deformation of the two-dimensional structure of a cushioning material according to a third embodiment of the present invention and the behavior of a rigid portion and a flexible portion when compressed. [Figure 13] 1 is a graph showing the relationship between the compression amount and the reaction force of a cushioning material made from a general foam material, and the change during the cycle from compression to restoration to the original state. [Figure 14] 10 is a graph showing the relationship between the compression amount and the reaction force of the cushioning material according to the present invention, which shows the change during the cycle from compression to restoration to the original state. [Figure 15] 3 is a schematic diagram showing another example of the configuration of the rigid portion in the two-dimensional structure shown in FIG. 2. FIG. [Figure 16] 9 is a schematic diagram showing another example of a two-dimensional structure in which the rigid portions in the two-dimensional structure shown in FIG. 8 are replaced with rigid portions of other shapes. [Figure 17] FIG. 10 is a side view showing another example of the configuration of footwear using the cushioning material according to the present invention in the sole. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the cushioning material according to the present invention and footwear using the same as a sole will be described with reference to the drawings. First, the overall structure of footwear 11 using the cushioning material according to the present invention as a sole will be described with reference to Fig. 1.

[0024] Footwear 11 includes an upper 13 and a sole 15. Upper 13 is configured to form a space for accommodating the foot of a wearer wearing footwear 11, and generally covers the area from the toes to the instep. Sole 15 is attached below upper 13 and forms the bottom of footwear 11.

[0025] In the illustrated embodiment of footwear 11, sole 15 has outer sole 15a and midsole 15b. Outer sole 15a constitutes the ground-contacting portion and is preferably formed from an elastic material. Examples of elastic materials include rubber, foamed resin, and elastomer materials. Midsole 15b is provided above outer sole 15a and is formed from cushioning material 17 having a three-dimensional lattice structure. Upper 13 is attached to midsole 15b.

[0026] FIG. 2 shows a detailed schematic side view of the two-dimensional structure of the cushioning material 17 used as the midsole 15b. The cushioning material 17 has a compression direction, a length direction perpendicular to the compression direction, and a width direction perpendicular to the compression direction and the length direction. In FIG. 2, the vertical direction is the compression direction, the horizontal direction is the length direction, and the direction perpendicular to the paper surface is the width direction. The three-dimensional structure constituting the cushioning material 17 is formed by juxtaposing multiple basic structural elements 19, each having the structure shown in FIG. 2 and extending in the compression direction and the length direction, in the width direction, and connecting adjacent basic structural elements 19 to each other in the width direction. In other words, the two-dimensional structure shown in FIG. 2 becomes the basic structural element 19. The basic structural element 19 is formed from a deformable and elastic material. Furthermore, the basic structural element 19 includes a plurality of rigid portions 21 and a plurality of flexible portions 23, and is configured such that the rigid portions 21 are connected to the surrounding rigid portions 21 via the flexible portions 23, and the rigid portions 21 and the flexible portions 23 are not directly connected to each other. The flexible portions 23 are deformable and have relatively high flexibility, and the rigid portions 21 have higher rigidity than the flexible portions 23. However, the rigid portions 21 are merely more rigid than the flexible portions 23 and have a certain degree of elasticity, so that they can apply a reaction force to the outside when compressed. The rigid portions 21 and the flexible portions 23 are preferably made of a deformable synthetic resin material having a certain degree of rigidity.

[0027] In detail, the flexible section 23 is constituted by a plurality of deformable struts 23a extending radially from a node 23b, and the rigid section 21 is constituted to have a polygonal shape and higher rigidity than the flexible section 23. Furthermore, the outer end of each deformed strut 23a of the flexible section 23 is connected to one of the vertices of each rigid section 21 arranged around the flexible section 23, and each vertex of the rigid section 21 is connected to one of the deformed struts 23a of a different flexible section 23, so that adjacent rigid sections 21 are connected to each other via the flexible section 23. In other words, the rigid sections 21 and the flexible sections 23 are connected alternately. For example, when the rigid section 21 has an n-sided polygonal shape (n is an integer of 3 or more), the rigid section 21 can be constituted by n outer struts 21a extending along the sides connecting adjacent vertices and m inner struts 21b extending radially from a node 21c located at the center of gravity of the rigid section 21 to m vertices (m is an integer of 3 or more and n or less). By configuring rigid portion 21 in this manner, even if outer struts 21a and inner struts 21b have the same thickness as deformed struts 23a, the contour formed by outer struts 21a is reinforced by inner struts 21b extending radially from node 21c located at the center of gravity, thereby increasing the rigidity of rigid portion 21. Note that node 21c does not need to be located strictly at the center of gravity of rigid portion 21, as long as it is located near the center of gravity of rigid portion 21. Outer struts 21a, inner struts 21b, and deformed struts 23a are preferably made of a synthetic resin material that has a certain degree of elasticity and is deformable.

[0028] As long as the rigid portion 21 has a higher rigidity than the flexible portion 23, the rigid portion 21 can have any suitable structure. For example, the inner struts 21b may be connected to all vertices of the rigid portion 21, or, as in the illustrated embodiment, may be connected to only some of the vertices of the rigid portion 21. That is, the number m of inner struts 21b extending from the nodes 21c of the n-sided polygonal rigid portion 21 may be equal to n or may be less than or equal to (n-1). In the illustrated embodiment, m=3 and n=6. Furthermore, the rigid portion 21 may be formed so that the inside of the outer struts 21a is filled with the same material as the outer struts 21a, for example, to form a flat plate. It is also possible to eliminate the inner struts 21b in the rigid portion 21 and form the outer struts 21a constituting the rigid portion 21 so that they are thicker than the deformed struts 23a constituting the flexible portion 23, thereby making the rigid portion 21 more rigid than the flexible portion 23.

[0029] In the illustrated embodiment, three rigid portions 21 are arranged around each flexible portion 23 so as to surround the flexible portion 23, and six flexible portions 23 are arranged around each rigid portion 21 so as to surround the rigid portion 21. Furthermore, the flexible portion 23 is composed of three deformed struts 23a of equal length extending radially from one node 23b, and the outer end of each deformed strut 23a is connected to one of the vertices of each regular hexagonal rigid portion 21 arranged to surround the flexible portion 23, and each vertex of the rigid portion 21 is connected to one of the deformed struts 23a of a different flexible portion 23. Furthermore, in the illustrated embodiment, the rigid portion 21 is composed of outer struts 21a extending along the six sides connecting adjacent vertices of the regular hexagon and three inner struts 21b extending radially from a node 21c located at or near the center of gravity of the rigid portion 21 to every other vertex.

[0030] A plurality of juxtaposed basic structural elements 19 can be connected to each other in the width direction by various methods to form a three-dimensional structure. For example, as shown in Fig. 3, a plurality of basic structural elements 19 juxtaposed in the width direction may be connected by connecting struts 25 extending in the width direction at the vertices of the polygonal rigid portions of adjacent basic structural elements 19. In this case, it is preferable that the basic structural elements 19 are juxtaposed so that the rigid portions 21 of one basic structural element 19 face the rigid portions 21 of adjacent basic structural elements 19 in the width direction, and that the vertices of the polygonal rigid portions 21 of one basic structural element 19 are connected to the vertices of the opposing polygonal rigid portions 21 of other adjacent basic structural elements 19 by connecting struts 25 extending in the width direction. In this case, the polygonal rigid portions 21 of two adjacent basic structural elements 19 facing each other in the width direction may have rectangular cells formed by two outer struts 21a that connect adjacent vertices of each of the opposing rigid portions 21 and face each other in the width direction, and two connecting struts 25 that connect adjacent vertices in the width direction. These rectangular cells may be reinforced by diagonally extending reinforcing struts 27. The buffering characteristics can be varied in the width direction by adjusting the position of the reinforcing struts 27. Alternatively, as shown in FIG. 4, the outer struts 21a of the polygonal rigid portions 21 of two adjacent basic structural elements 19 facing each other in the width direction may be connected by connecting surfaces 29, thereby forming a three-dimensional structure in which the basic structural element 19 is swept in the width direction. Like the other struts, the connecting struts 25 and reinforcing struts 27 are preferably made of a synthetic resin material that has a certain degree of elasticity and is deformable.

[0031] Furthermore, when a three-dimensional structure is constructed by connecting basic structural elements 19 in the width direction with connecting struts 25, as shown in Fig. 5, it is possible to adjust the shock-absorbing characteristics in the width direction by changing the thickness of the outer struts 21a and inner struts 21b that constitute the rigid portion 21 of each basic structural element 19, the deformable struts 23a that constitute the flexible portion 23, and the connecting struts 25 and reinforcing struts 27 that connect the basic structural elements 19. Note that in Figs. 3 to 5, each rigid portion 21 is composed of six outer struts 21a and three inner struts 21b (more specifically, the three inner struts 21b that connect three of the six vertices of the hexagon to the nodes 21c).

[0032] Next, the operation of the cushioning material 17 having a three-dimensional structure configured as described above will be described with reference to Figure 6. Figure 6(a) shows the basic structural element 19 of the cushioning material 17 when no force in the compressive direction (compressive force) is acting, and Figure 6(b) shows the basic structural element 19 of the cushioning material 17 when compressed by a compressive force acting in the direction of the arrow. Figure 6 also shows a case in which the rigid part 21 of the basic structural element 19 is composed of six outer struts 21a and six inner struts 21b that connect all six vertices of a regular hexagon to nodes 21c.

[0033] 2 and 6, in the cushioning material 17, the rigid portion 21 and the flexible portion 23 are arranged and connected to each other so that the center of gravity of the rigid portion 21 is not located on an extension of the deformed struts 23a that constitute the flexible portion 23. With this arrangement and connection, the deformed struts 23a of the flexible portion 23 are connected at an angle so as to approach one of the two outer struts 21a extending along two adjacent sides of the rigid portion 21, and the angle that the deformed struts 23a form with one of the two adjacent outer struts 21a (i.e., sides) is smaller than the angle that the deformed struts 23a form with the other. As a result, when a compressive force is applied to the cushioning material 17 in the state shown in FIG. 6(a), as shown in FIG. 6(b), the rigid portion 21 moves to the side where the deformed struts 23a form a smaller angle with the outer struts 21a, and the rigid portion 21 and the flexible portion 23 rotate in opposite directions. In Figure 6, when a force (compressive force) is applied in the direction of the arrow in the compression direction, each rigid portion 21 moves diagonally downward to the right in Figure 6, while rotating around the center of gravity of the rigid portion 21 (i.e., node 21c) in a direction in which the outer strut 21a and the deformed strut 23a come closer together (i.e., counterclockwise), and each flexible portion 23 also moves diagonally downward to the right in Figure 6, while the deformed strut 23a of the flexible portion 23 rotates clockwise around the center of gravity of the flexible portion 23 (i.e., node 23b). As a result, the flexible portion 23 is crushed and compressed, and the cushioning material 17 can absorb impact while increasing its density. When a force is further applied in the compression direction from this state, the force is transmitted and acted on each other between the rigid portions 21, causing the rigid portions 21 to elastically deform and increase their elasticity, allowing a large reaction force to be applied during the restoration process. Such deformation while rotating is achieved because the rigid portions 21 and the flexible portions 23 are not directly connected to each other, and the rigid portions 21 and the flexible portions 23 are alternately connected and rotate in opposite directions. Also, as described above, the deformation struts 23a of the flexible portions 23 are connected at an angle so as to approach one of the two outer struts 21a extending along two adjacent sides of the rigid portion 21, thereby regulating the direction of rotation of the rigid portions 21 and the flexible portions 23 when a compressive force is applied, and the cushioning material 17 is smoothly compressed.

[0034] In the embodiment of the cushioning material 17 shown in Figures 1 to 6, the rigid portion 21 has a regular hexagonal shape, and the flexible portion 23 is composed of three deformed struts 23a extending radially from nodes 23b. However, as described above, if the cushioning material 17 is composed of rigid portions 21 and flexible portions 23, and the rigid portions 21 and flexible portions 23 are alternately connected to each other so that the rigid portions 21 and flexible portions 23 rotate in opposite directions around their respective centers of gravity, it will be possible to first exhibit high shock absorption and then high resilience. Therefore, the cushioning material 17 can be constructed based on various two-dimensional structures in addition to the two-dimensional structure of the illustrated embodiment.

[0035] An example of a procedure for designing the two-dimensional structure of the basic structural element 19 of the cushioning material 17 according to the present invention will be described below with reference to FIGS.

[0036] 7, a plurality of polygonal first elements 51 and a plurality of polygonal second elements 53 are arranged in a plane-filling pattern in which the polygonal first elements 51 and the polygonal second elements 53 are alternately adjacent to each other and located in a plane extending in the compression direction (vertical direction in the figure) and the length direction (horizontal direction in the figure) so that each vertex of the first element 51 is connected to a vertex of one of the polygonal second elements 53. The first elements 51 and the second elements 53 do not need to have the same polygonal shape, and each element (first elements 51 or second elements 53) may include elements with different polygonal shapes. The plane filling pattern is preferably a combination of hexagons and triangles as shown in Fig. 7(a), a combination of quadrangles and quadrangles as shown in Fig. 7(b), a combination of triangles and triangles as shown in Fig. 7(c), or a combination of triangles, quadrangles, and pentagons as shown in Fig. 7(d). The polygons are preferably regular polygons with all sides of equal length, but may also be polygons with unequal side lengths.

[0037] Next, as shown in FIG. 8, the first element 51 and the second element 53 arranged in the above-described plane-filling pattern are replaced with a rigid portion 21 and a flexible portion 23, respectively. The flexible portion 23 is composed of a plurality of deformable struts extending radially from the nodes so as to connect the center of gravity or the vicinity of the center of gravity of the second element 53 with each vertex. FIGS. 8(a) to 8(d) correspond to the two-dimensional structures after the above-described replacement of the two-dimensional structures shown in FIGS. 7(a) to 7(d), respectively. The two-dimensional structure of the basic structural element 19 shown in FIG. 2 was designed based on the two-dimensional structure shown in FIG. 8(a).

[0038] Next, to define the direction of rotation of the rigid portion 21 and flexible portion 23 in the basic structural element 19, as shown in Figure 9, the rigid portion 21 is rotated around its center of gravity or a position near the center of gravity so that the deforming struts 23a of the flexible portion 23 are tilted relative to the axis connecting the center of gravity or a point near the center of gravity of the rigid portion 21 and each vertex, and accordingly the deforming struts 23a of the flexible portion 23 are deformed so as to be rotated around the center of gravity or a position near the center of gravity (i.e., node 23b) of the flexible portion 23 in the opposite rotational direction to the rigid portion 21. When the cushioning material 17 is compressed, the rigid portion 21 moves in a direction tilted by the above-mentioned angle θ relative to the compression direction, and the compression direction is determined. For example, in Figure 9(b), the rigid section 21 is rotated clockwise by angle θ and the deforming struts 23a of the flexible section 23 are tilted counterclockwise toward the outer struts 21a of the rigid section 21, so that the rigid section 21 moves downward and left in the figure when the cushioning material 17 is compressed. Therefore, if the cushioning material 17 is attached to the sole 15 so that the left direction in Figure 9(b) corresponds to the running direction, the sole 15 moves forward while compressing when it touches the ground, making it possible to assist in shifting the center of gravity while running.

[0039] 10 to 12 each show the compression process of an example structure of a basic structural element 19 designed in the illustrated manner.

[0040] Figure 10(a) is the same as the basic structural element 19 shown in Figure 8(a). Figure 10(b) shows the basic structural element 19 shown in Figure 10(a) after the rigid portion 21 and the flexible portion 23, which are hexagonal rigid portion 21 and three deformed struts 23a extending radially from the nodes 23b, have been rotated in order to orient the rotation of the flexible portion 23. When used as a cushioning material 17, it is preferable to use one manufactured in the state shown in Figure 10(b). Even such a complex structure can be manufactured using a 3D printer. When a compressive force is applied from above to the basic structural element 19 shown in FIG. 10(b) in the compression direction, as shown in FIG. 10(c), the hexagonal rigid portion 21 rotates counterclockwise around its center of gravity or a position near its center of gravity, while the deforming struts 23a of the flexible portion 23 rotate clockwise around nodes 23b, causing the flexible portion 23 to rotate clockwise around its center of gravity or a position near its center of gravity. As a result, the flexible portion 23 collapses, and the basic structural element 19 is compressed in the compression direction while increasing its density. This allows the basic structural element 19 to exert a cushioning effect. When further compressive force is applied to the basic structural element 19 from the state shown in FIG. 10(c), the compressive force is transmitted between the rigid portions 21, causing the rigid portions 21 to deform while maintaining a certain degree of elasticity. This elastic deformation of the rigid portions 21 allows the basic structural element 19 to provide a large reaction force to the outside when the rigid portions 21 are restored.

[0041] Figure 11(a) is the same as the basic structural element 19 shown in Figure 8(b). Figure 11(b) shows the basic structural element 19 shown in Figure 11(a) after the rigid portion 21 and flexible portion 23 have been rotated in order to orient the rotation of the rectangular rigid portion 21 and flexible portion 23, which consists of four deformed struts 23a extending radially from the nodes 23b. When used as a cushioning material 17, it is preferable to use one manufactured in the state shown in Figure 11(b). Even such a complex structure can be manufactured using a 3D printer. As in the embodiment shown in FIG. 10 , when a compressive force is applied from above to the basic structural element 19 shown in FIG. 11( b ), as shown in FIG. 11( c ), the rectangular rigid portion 21 rotates counterclockwise around its center of gravity or a position near its center of gravity, while the deformed struts 23 a of the flexible portion 23 rotate clockwise around nodes 23 b, causing the flexible portion 23 to rotate clockwise around its center of gravity or a position near its center of gravity. As a result, the flexible portion 23 collapses, compressing the basic structural element 19 in the compression direction while increasing its density. This allows the basic structural element 19 to exert a cushioning effect. When further compressive force is applied to the basic structural element 19 from the state shown in FIG. 11( c ), the compressive force is transmitted between the rigid portions 21, causing the rigid portions 21 to deform while maintaining a certain degree of elasticity. This elastic deformation of the rigid portions 21 allows the basic structural element 19 to provide a large reaction force to the outside when the rigid portions 21 are restored.

[0042] Figure 12(a) is similar to the basic structural element 19 shown in Figure 8(d). Figure 12(b) shows the basic structural element 19 shown in Figure 12(a) in which the rigid portion 21 and flexible portion 23 have been rotated to change the direction of rotation of the flexible portion 23, which consists of a polygonal rigid portion 21 (e.g., triangular, quadrangular, pentagonal, or hexagonal) and a plurality of deformed struts 23a (e.g., three, four, or five) extending radially from nodes 23b. When used as a cushioning material 17, it is preferable to use one manufactured in the state shown in Figure 12(b). Even such a complex structure can be manufactured using a 3D printer. As in the embodiment shown in FIG. 10 , when a compressive force is applied from above to the basic structural element 19 shown in FIG. 12( b ), as shown in FIG. 12( c ), the polygonal rigid portion 21 rotates counterclockwise around its center of gravity or a position near its center of gravity, while the deforming struts 23 a of the flexible portion 23 rotate clockwise around nodes 23 b, causing the flexible portion 23 to rotate clockwise around its center of gravity or a position near its center of gravity. As a result, the flexible portion 23 collapses, compressing the basic structural element 19 in the compression direction while increasing its density. This allows the basic structural element 19 to exert a cushioning effect. When further compressive force is applied to the basic structural element 19 from the state shown in FIG. 11( c ), the compressive force is transmitted between the rigid portions 21, causing the rigid portions 21 to deform while maintaining a certain degree of elasticity. This elastic deformation of the rigid portions 21 allows the basic structural element 19 to provide a large reaction force to the outside when the rigid portions 21 are restored. [Example]

[0043] The results of an experiment to verify the characteristics of the cushioning material 17 according to the present invention will be described with reference to Figures 13 and 14. Figure 13 is a graph showing the relationship between the compression stroke and reaction force of a cushioning material made from a general foam resin material, which changes over the cycle from compression to restoration to the original state, and Figure 14 is a graph showing the relationship between the compression stroke and reaction force of the cushioning material 17 according to the present invention, which changes over the cycle from compression to restoration to the original state.

[0044] As can be seen from Figure 13, for a typical foam resin material, the compression amount and the reaction force are nearly proportional, and there is little difference between the compression and recovery times. In contrast, as can be seen from Figure 14, for the cushioning material 17 of the present invention, during compression, a low-rigidity region A, where the compression amount is relatively large with respect to a small change in force, is followed by a high-rigidity region B, where a larger force is required per unit compression amount, indicating a change in characteristics. Furthermore, during recovery, the cushioning material 17 generally exhibits a smaller reaction force relative to the amount of recovery from compression than a foam material, with the difference being particularly large in the low-rigidity region A. From these results, it can be seen that the low-rigidity region A exhibits high shock absorption, while the high-rigidity region B exhibits stability due to its high rigidity. Therefore, when such cushioning material 17 is used in the sole 15 of footwear, the low-rigidity region A compresses upon contact with the ground, thereby exhibiting high shock absorption. Furthermore, as compression progresses, the high-rigidity region B exhibits high rigidity, providing the foot of the footwear wearer with the stability required for shifting the center of gravity and for pushing off the ground, thereby assisting running. Here, "rigidity" is an index that indicates the resistance of a material to deformation, and the cushioning material 17 according to the present invention is not simply suppressed from deformation and restricted in movement even in the high rigidity region B, but has the property of exerting a greater reaction force against compression while maintaining a certain degree of elasticity.

[0045] While the cushioning material 17 according to the present invention and footwear 11 using the same as a midsole 15b have been described above with reference to the illustrated embodiment, the present invention is not limited to the illustrated embodiment. For example, in the illustrated embodiment, the cushioning material 17 employs a basic structural element 19 composed of a hexagonal rigid portion 21 and a flexible portion 23 composed of three deformed struts 23a extending radially from a node 23b. However, as long as the basic structural element 19 is composed of rigid portions 21 and flexible portions 23 that rotate in opposite directions and are alternately connected, it is possible to use a basic structural element 19 with another pattern, such as that shown in FIG. 8, for the cushioning material 17. Furthermore, in the illustrated embodiment, the hexagonal rigid portion 21 is composed of six outer struts 21a extending along sides connecting adjacent vertices and three inner struts 21b extending radially from a node 21c located at or near the center of gravity of the rigid portion 21 to every other vertex in the circumferential direction. However, as in the basic structural element 19' shown in Figure 15, the rigid body portion 21 may be composed of six outer struts 21a extending along sides connecting adjacent vertices and six inner struts 21b extending radially from a node 21c located at or near the center of gravity of the rigid body portion 21 to all six vertices. Instead of a polygonal rigid body portion 21 (e.g., the hexagonal, rectangular, and triangular rigid body portions 21 shown in Figures 8(a), (b), and (c)), a polygonal circumscribed circular rigid body portion 21' as shown in Figures 16(a), (b), and (c) may be used. In this case, the outer shape of the rigid body portion 21' may be formed by connecting adjacent vertices of the first element 51 with outer struts extending in an arc shape. Furthermore, the sole 15 of the illustrated footwear 11 includes an outer sole 15a and a midsole 15b, and the midsole 15b uses a cushioning material 17, but the outer sole 15a may also use a cushioning material 17. Furthermore, as shown in Figure 17, the sole 15 may be formed only by the outer sole 15a without providing the midsole 15b, and the entire sole 15 may be formed by the cushioning material 17. [Explanation of symbols]

[0046] 11. Footwear 13 Upper 15 soles 15a outer sole 15b midsole 17 Cushioning material 19 Basic structural elements 19' Basic structural elements 21 Rigid part 21' rigid section 21a outer strut 21b medial strut 21c nodule 23 Flexible section 23a Deformed strut 23b Nodule 25 Connecting strut 27 Reinforcing strut 51 First Element 53 Second Element

Claims

1. A cushioning material having a three-dimensional structure that has a compression direction, a length direction perpendicular to the compression direction, and a width direction perpendicular to the compression direction and the length direction, and is deformable in the compression direction, the three-dimensional structure is configured by juxtaposing a plurality of basic structural elements, each extending in the compression direction and the length direction, in the width direction and connecting them to each other; the basic structural element includes a plurality of polygonal or polygonal circumscribed circular rigid portions having relatively high rigidity and a plurality of flexible portions having relatively low rigidity; In a plane-filling pattern in which a plurality of polygonal first elements and a plurality of polygonal second elements are alternately adjacent and arranged in a plane extending in the compression direction and the length direction such that each vertex of a polygonal first element is connected to a vertex of one of the polygonal second elements, the basic structural element is formed by replacing the first elements with rigid parts having the polygonal shape or a circumscribed circle shape of the polygon, and replacing the second elements with flexible parts; The flexible portion is composed of a plurality of deformable struts extending radially from the center of gravity of the second element so as to connect the center of gravity of the second element to all vertices of the second element, and the rigid portion and the flexible portion are arranged so that when the basic structural element is compressed in the compression direction, the rigid portion rotates around the center of gravity of the rigid portion in one of a clockwise and counterclockwise direction, and the plurality of deformable struts of the flexible portion rotate around the center of gravity of the flexible portion in the other of a clockwise and counterclockwise direction.

2. 2. The cushioning material of claim 1, wherein the rigid portion is composed of a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element and a plurality of inner struts extending radially from the center of gravity of the rigid portion to a plurality of vertices.

3. 2. The cushioning material of claim 1, wherein the rigid portion is formed by a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element, the outer struts being thicker than the deformed struts.

4. The cushioning material according to claim 1 , wherein the rigid portion is formed of a flat plate having a polygonal shape or a circumscribed circle shape of a polygon.

5. 2. The cushioning material of claim 1, wherein a plurality of the basic structural elements are arranged side by side in the width direction, the rigid portions within the basic structural elements are each opposed to the rigid portions within adjacent basic structural elements in the width direction, and the three-dimensional structure is formed by connecting each vertex of the rigid portion within the basic structural element to each vertex of the opposing rigid portion in another adjacent basic structural element in the width direction by connecting struts.

6. The cushioning material described in Claim 5, wherein the rigid portion includes a plurality of outer struts extending along edges or arcs connecting adjacent vertices of the first element, and a rectangular cell formed by the two outer struts connecting adjacent vertices in the opposing rigid portions of two adjacent basic structural elements and the two connecting struts connecting the adjacent vertices in the width direction is reinforced by reinforcing struts extending diagonally.

7. The cushioning material according to claim 1 , wherein the three-dimensional structure connects the plurality of basic structural elements in the width direction so as to sweep the basic structural elements in the width direction.

8. 2. The cushioning material according to claim 1, wherein the first elements and the second elements are configured by a combination of a hexagonal first element and a triangular second element, a combination of a quadrangular first element and a quadrangular second element, or a combination of a triangular first element and a triangular second element.

9. The cushioning material of claim 1, wherein the multiple deforming struts of the flexible section are arranged tilted at the same angle in the same direction around the rigid section with respect to an axis connecting the center of gravity of the rigid section to which each deforming strut is connected and the vertex of the rigid section to which the deforming strut is connected.

10. Footwear comprising an upper for accommodating a wearer's foot and a sole attached below the upper to form a bottom, Footwear, characterized in that the sole comprises the cushioning material according to any one of claims 1 to 8.

11. Footwear according to claim 10, wherein the sole includes a first cushioning layer made of the cushioning material and a second cushioning layer formed of an elastic material, the first cushioning layer and the second cushioning layer being stacked.

12. Footwear according to claim 11, wherein the elastic material is a foamed resin material, a rubber material, or an elastomeric material.

13. Footwear as described in claim 10, wherein the multiple deformation struts of the flexible portion of the cushioning material are arranged tilted at the same angle in the same direction around the rigid portion with respect to an axis connecting the center of gravity of the rigid portion to which each deformation strut is connected and the vertex of the rigid portion to which the deformation strut is connected.

14. Footwear according to claim 13, wherein the deforming struts of the flexible portion are connected to the vertices of the rigid portion of the cushioning material at an angle relative to an axis connecting the center of gravity of the rigid portion and the vertex, in a direction in which the rigid portion moves diagonally downward toward the direction of travel when the cushioning material is compressed.

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