footwear

Abstract

A footwear (1A) comprises a footbed portion (10A) that supports a sole of foot of a wearer and in which a grounding face (12) is provided. The footbed portion (10A) comprises a buffer portion (13) composed of a single member made of an elastic material having a modulus of elasticity of between 0.1 MPa and 100 MPa both inclusive. The buffer portion (13) is composed of a three-dimensional mesh structure in which a solid lattice structure in which a plurality of pillar portions are connected to each other is a unit structure and that is obtained by repeatedly arraying a plurality of the unit structures. A maximum external dimension of a cross section orthogonal to an extending direction of each of the plurality of pillar portions is between 1.0 mm and 1.8 mm both inclusive. The thickness of the buffer portion (13) in a direction orthogonal to the grounding face (12) is 25.0 mm or greater.

Description

Footwear

[0001] The present invention relates to footwear such as sandals, shoes, or shoes fitted with insoles.

[0002] For example, Japanese Patent Laid-Open Publication No. 2018-187363 (Patent Document 1) discloses a footwear sole manufactured by three-dimensional additive manufacturing. The sole disclosed in this publication is composed of a three-dimensional mesh structure having a three-dimensional lattice structure as a unit structure.

[0003] Japanese Patent Application Laid-Open No. 2018-187363

[0004] For example, recovery shoes (recovery sandals) used for recovering from fatigue by dispersing foot pressure, supporting the arch of the foot, and supporting the heel against pronation, etc., require high deformability in the footbed. This high deformability does not simply mean that the footbed is soft; it must be able to prevent bottoming out (a state in which the footbed deforms upon landing, compressing it to almost its maximum extent and not easily deforming any further) and stably support the wearer's foot in its deformed state.

[0005] In order to achieve such deformability, it is necessary to design the cushioning portion provided in the footbed portion not only from the viewpoint of material but also from the viewpoint of structure, and it is assumed that this will be constructed with a three-dimensional mesh structure having a three-dimensional lattice structure as a unit structure, as disclosed in the above publication. However, the sole disclosed in the above publication is designed to ensure high durability and good comfort for athletic use, and no consideration has been given to preventing bottoming out.

[0006] Furthermore, the ability to have such high deformability while suppressing bottoming out and providing stable support for the wearer's feet is not something that is required only for footwear used for the recovery purposes mentioned above, but can also be required for footwear used for other purposes, depending on the situation in which they are used.

[0007] Therefore, the present invention has been made in consideration of such circumstances, and aims to provide footwear that does not bottom out when worn and can stably support the wearer's feet even in a deformed state.

[0008] The footwear according to the present invention includes a footbed portion that supports the sole of a wearer's foot and is provided with a ground-contact surface. The footbed portion includes a cushioning portion constructed of a single member made of an elastic material having an elastic modulus of 0.1 MPa to 100 MPa, the cushioning portion comprising a three-dimensional mesh structure in which a plurality of interconnected columnar portions form a unit structure, and the unit structures are repeatedly arranged in multiple rows. Each of the columnar portions has a maximum outer dimension of 1.0 mm to 1.8 mm in a cross section perpendicular to its extension direction, and the thickness of the cushioning portion in the direction perpendicular to the ground-contact surface is 25.0 mm or more.

[0009] According to the present invention, it is possible to provide footwear that does not bottom out when worn and that can stably support the wearer's foot even in a deformed state.

[0010] 1 is a perspective view of a sandal according to a first embodiment, as seen from the diagonally upper front side. FIG. 2 is a perspective view of the sandal shown in FIG. 1, as seen from the diagonally lower rear side. FIG. 3 is a plan view of the sandal shown in FIG. 1. FIG. 4 is a side view of the sandal shown in FIG. 1, as seen from the outer foot side. FIG. 5 is a schematic view for explaining the three-dimensional structure of the buffer section of the sandal shown in FIG. 1. FIG. 6 is a schematic view showing a state at the start of molding of the sandal main body by three-dimensional additive manufacturing in a manufacturing method for the sandal shown in FIG. 1. FIG. 7 is a schematic view showing a state in an intermediate stage of molding of the sandal main body by three-dimensional additive manufacturing in a manufacturing method for the sandal shown in FIG. 1. FIG. 8 is a schematic view showing a state at the end of molding of the sandal main body by three-dimensional additive manufacturing in a manufacturing method for the sandal shown in FIG. 1. FIG. 9 is a schematic view showing another manufacturing method for the sandal shown in FIG. 1. FIG. 10 is a schematic view showing a state of the sole section of the sandal shown in FIG. 1 when landing and when stepping out. FIG. 11 is a schematic view showing the distribution of thicknesses of columnar sections in the buffer section of the sandal shown in FIG. 1. FIG. 12 is a graph showing the results of a first verification test. FIG. 13 is a graph showing the results of a second verification test. FIG. 14 is a schematic view showing the distribution of thicknesses of columnar sections in the buffer section of a sandal according to a first modified example. 20. A schematic cross-sectional view of a footbed portion of a sandal according to a second modified example. A schematic cross-sectional view of a footbed portion of a sandal according to a third modified example. A schematic cross-sectional view of a footbed portion of a sandal according to a fourth modified example. A schematic diagram for explaining the three-dimensional structure of a buffer portion of a sandal according to a fifth modified example. A perspective view of a shoe according to a second embodiment. A perspective view of a shoe according to a third embodiment. A schematic cross-sectional view taken along line XXI-XXI shown in FIG. 20. An exploded view of the shoe shown in FIG. 20. A perspective view of a shoe according to a fourth embodiment and an insole provided therein.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated. Note that the term "wearer" used in the following description refers to a person of average build whose feet fit the size of the footwear.

[0012] <First Embodiment> Fig. 1 is a perspective view of a sandal according to a first embodiment, as seen from the diagonally upper right front side, and Fig. 2 is a perspective view of the sandal shown in Fig. 1, as seen from the diagonally lower left rear side. Fig. 3 is a plan view of the sandal shown in Fig. 1, and Fig. 4 is a side view of the sandal shown in Fig. 1, as seen from the outer side of the foot. First, the configuration of a sandal 1A according to this embodiment will be described with reference to Figs. 1 to 4.

[0013] 1 to 4, the sandal 1A includes a sandal body 20 including a sole portion 21 and a belt portion 22. The sandal body 20 is made of a single member, and is composed of a shaped object 2 produced by a three-dimensional additive manufacturing method using a photolithography method, which will be described later.

[0014] The sole portion 21 constitutes the footbed portion 10A that supports the wearer's foot. The upper surface 21a of the sole portion 21 defines the support surface 11 that supports the sole of the wearer's foot when the sole is worn, and the lower surface 21b of the sole portion 21 defines the contact surface 12 that comes into contact with the ground, floor, or the like when the sole is worn.

[0015] In the sandal 1A according to this embodiment, the periphery of the upper surface 21a of the sole portion 21 is configured to be raised so that, when worn, the wearer's foot is positioned on the support surface 11. Therefore, the upper surface 21a of the sole portion 21 has a concave shape as a whole, and the portion of the concave upper surface 21a that defines the bottom corresponds to the support surface 11.

[0016] The support surface 11 is preferably made of a material that is non-slip and flexible, providing a comfortable fit, and the ground contact surface 12 is preferably made of a non-slip material. In the sandal 1A according to this embodiment, the support surface 11 and the ground contact surface 12 are made of a part of the sandal body 20, which is a single member, and therefore both the support surface 11 and the ground contact surface 12 are made of a non-slip and flexible material. However, the support surface 11 and the ground contact surface 12 may be made individually of members having different materials or hardnesses.

[0017] In the sandal 1A according to this embodiment, the entire sole portion 21 serving as the footbed portion 10A is constructed to be flexible, and as a result, the entire sole portion 21 functions as the buffer portion 13. This buffer portion 13 is not only soft, but also has improved performance so that it can stably support the wearer's foot in a deformed state without bottoming out, the details of which will be described later.

[0018] As shown in Figures 3 and 4, the sole portion 21 of the sandal 1A, when viewed in a plane (i.e., when viewed along a direction perpendicular to the ground surface 12), is divided along the front-to-back direction (the up-and-down direction in Figure 3 and the left-and-right direction in Figure 4) that coincides with the longitudinal direction of the wearer's foot into a forefoot portion R1 that supports the toes and footbed of the wearer's foot, a midfoot portion R2 that supports the arch of the wearer's foot, and a rearfoot portion R3 that supports the heel of the wearer's foot.

[0019] Here, if the front end of the sole portion 21 is taken as the reference point, and the position corresponding to 30% of the longitudinal dimension of the sole portion 21 from the front end is taken as the first boundary position, and the position corresponding to 80% of the longitudinal dimension of the sole portion 21 from the front end is taken as the second boundary position, the forefoot portion R1 corresponds to the portion included between the front end and the first boundary position along the longitudinal direction, the midfoot portion R2 corresponds to the portion included between the first boundary position and the second boundary position along the longitudinal direction, and the rear foot portion R3 corresponds to the portion included between the second boundary position and the rear end of the sole along the longitudinal direction.

[0020] As shown in FIG. 3, when viewed in a plan view, the sandal 1A is divided along the left-right direction (left-right direction in the drawing) that corresponds to the width direction of the wearer's foot into an inner foot portion (the portion on the S1 side shown in the drawing) that corresponds to the midline side (i.e., the side closer to the midline) of the anatomical orthogonal position of the foot, and an outer foot portion (the portion on the S2 side shown in the drawing) that corresponds to the side opposite the midline side of the anatomical orthogonal position of the foot (i.e., the side farther from the midline).

[0021] 1 to 4, the belt portion 22 constitutes the foot cover portion 10B that covers the instep of the wearer's foot and is located above the sole portion 21. In the sandal 1A according to this embodiment, the belt portion 22 has a strap-like shape.

[0022] The belt portion 22 extends in the left-right direction so as to have a generally arched shape when viewed in the front-rear direction. One end of the belt portion 22 is connected to the end of the sole portion 21 on the medial side of the foot, and the other end of the belt portion 22 is connected to the end of the sole portion 21 on the lateral side of the foot.

[0023] As a result, an opening 23 is formed by the peripheral edge of the upper surface 21a of the sole part 21 located behind the belt part 22 and the rear end of the belt part 22, and a hollow part is provided between the sole part 21 and the belt part 22. Therefore, the sandal 1A can be put on by inserting the wearer's foot into the hollow part through the opening 23.

[0024] In addition to the opening 23, the sandals 1A according to this embodiment also have a front opening 24 formed by the periphery of the upper surface 21a of the sole 21 at a portion located forward of the belt 22 and the front end of the belt 22. When worn, the wearer's toes are exposed to the outside through the front opening 24.

[0025] The material of the sandal body 20 is not particularly limited, but is preferably a resin or rubber material that can be molded using a three-dimensional additive manufacturing method using stereolithography, and that ensures that the molded sandal body 20 has appropriate flexibility, extensibility, durability, elasticity, stability, etc. More specifically, if the sandal body 20 is made of resin, it can be made of, for example, polyolefin resin, ethylene-vinyl acetate copolymer (EVA), polyamide-based thermoplastic elastomer (TPA, TPAE), thermoplastic polyurethane (TPU), or polyester-based thermoplastic elastomer (TPEE). On the other hand, if the sandal body 20 is made of rubber, it can be made of, for example, butadiene rubber (BR).

[0026] The sandal body 20 may also be made of a polymer composition. In this case, examples of the polymer contained in the polymer composition include olefin-based polymers such as olefin-based elastomers and olefin-based resins. Examples of olefin-based polymers include polyethylene (e.g., linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE)), polypropylene, ethylene-propylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1-pentene copolymers, propylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-4-methyl-pentene copolymers, ethylene-1-butene copolymers, 1-butene-1-hexene copolymers, 1-butene-4-methyl-pentene, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene- Examples of polyolefins include ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylic acid copolymer, propylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, and propylene-vinyl acetate copolymer.

[0027] The polymer may be an amide polymer such as an amide elastomer or an amide resin, for example, polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, etc.

[0028] The polymer may also be an ester-based polymer such as an ester-based elastomer or an ester-based resin, etc. Examples of the ester-based polymer include polyethylene terephthalate and polybutylene terephthalate.

[0029] The polymer may be a urethane polymer such as a urethane elastomer or a urethane resin, etc. Examples of the urethane polymer include polyester polyurethane and polyether polyurethane.

[0030] The polymer may also be a styrene-based polymer such as a styrene-based elastomer or a styrene-based resin. Examples of styrene-based elastomers include styrene-ethylene-butylene copolymer (SEB), styrene-butadiene-styrene copolymer (SBS), hydrogenated SBS (styrene-ethylene-butylene-styrene copolymer (SEBS)), styrene-isoprene-styrene copolymer (SIS), hydrogenated SIS (styrene-ethylene-propylene-styrene copolymer (SEPS)), styrene-isobutylene-styrene copolymer (SIBS), styrene-butadiene-styrene-butadiene (SBBSB), and styrene-butadiene-styrene-butadiene-styrene (SBSBS). Examples of styrene-based resins include polystyrene, acrylonitrile-styrene resin (AS), and acrylonitrile-butadiene-styrene resin (ABS).

[0031] Furthermore, the polymer may be, for example, an acrylic polymer such as polymethyl methacrylate, a urethane-based acrylic polymer, a polyester-based acrylic polymer, a polyether-based acrylic polymer, a polycarbonate-based acrylic polymer, an epoxy-based acrylic polymer, a conjugated diene polymer-based acrylic polymer and a hydrogenated product thereof, a urethane-based methacrylic polymer, a polyester-based methacrylic polymer, a polyether-based methacrylic polymer, a polycarbonate-based methacrylic polymer, a polyester-based urethane acrylate, a polycarbonate-based urethane acrylate, a polyether-based urethane acrylate, an epoxy-based methacrylic polymer, a conjugated diene polymer-based methacrylic polymer and a hydrogenated product thereof, a polyvinyl chloride resin, a silicone-based elastomer, butadiene rubber, isoprene rubber (IR), chloroprene rubber (CR), natural rubber (NR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), or the like.

[0032] As mentioned above, the sandal body 20 is preferably made of a material that is non-slip and flexible, providing a comfortable fit. Among the above-mentioned materials, urethane acrylate is particularly preferable. If the sandal body 20 is made of urethane acrylate, it will not only be durable and stretchable, but also have sufficient elasticity. As mentioned above, the sandal body 20 is manufactured using a stereolithography three-dimensional additive manufacturing method, and therefore the sandal body 20 will contain a curing agent as a secondary component.

[0033] Here, the sandal 1A according to this embodiment has improved performance not only in terms of materials as described above, but also in terms of structure. More specifically, in the sandal 1A, the sole portion 21 as the footbed portion 10A functioning as the shock-absorbing portion 13 is made of a three-dimensional mesh structure as described below, and the three-dimensional mesh structure of the portion constituting the shock-absorbing portion 13 satisfies predetermined shape and dimensional conditions, so that the sandal 1A is configured to be able to stably support the wearer's foot in a deformed state without bottoming out.

[0034] This point will be described in detail below with reference to Figures 5(A) and 5(B) and the aforementioned Figure 4. Here, Figure 5(A) is a schematic diagram for explaining the three-dimensional structure of the buffer part of the sandal shown in Figure 1, and Figure 5(B) is a schematic diagram for explaining the three-dimensional structure of the buffer part having a configuration similar to the structure shown in Figure 5(A).

[0035] As shown in Fig. 5A, the sole portion 21, which functions as the buffer portion 13 of the sandal 1A, is composed of a three-dimensional mesh structure 3A in which a plurality of unit structures 4A each having a three-dimensional lattice structure are repeatedly arranged. More specifically, the plurality of unit structures 4A are regularly and continuously repeated along each of the width direction (X direction shown in the figure), depth direction (Y direction shown in the figure), and height direction (Z direction shown in the figure). Fig. 5A shows only a few unit structures 4A that are adjacent in each of the width direction, depth direction, and height direction.

[0036] The unit structure 4A, which is a three-dimensional lattice structure, has a three-dimensional shape formed by interconnecting multiple columnar portions 6 extending in a predetermined direction. The multiple columnar portions 6 are configured so that the extension directions of adjacent columnar portions 6 intersect, thereby forming a three-dimensional lattice structure. The unit structure 4A shown in the figure is called a fluorite lattice. The unit space 5A occupied by the unit structure 4A has a polyhedral shape, and in the illustrated unit structure 4A, this is a hexahedral shape.

[0037] In the three-dimensional mesh structure 3A shown in Figure 5(A), each of the multiple columnar portions 6 is configured to have a substantially cylindrical outer shape. Therefore, the cross-sectional shape of each of the multiple columnar portions 6 perpendicular to the extension direction is substantially circular. In addition, in the three-dimensional mesh structure 3A shown in the figure, the thickness of each of the multiple columnar portions 6 is configured to continuously change along the extension direction. Specifically, the thickness is large at the connection portion between adjacent columnar portions 6 and becomes smaller with increasing distance from the connection portion. This configuration makes it possible to increase durability while maintaining flexibility.

[0038] On the other hand, the three-dimensional mesh structure 3A' shown in Figure 5(B) has a three-dimensional structure similar to the structure shown in Figure 5(A), in which the unit structures 4A' are fluorite lattices and the unit spaces 5A' occupied by the unit structures 4A' are hexahedral. However, unlike the structure shown in Figure 5(A), the three-dimensional mesh structure 3A' has a structure in which the thickness of each of the multiple columnar portions 6 is uniform along its extension direction. The three-dimensional mesh structure 3A' having such a configuration may be applied to the cushioning portion 13 of the sandal 1A according to this embodiment, instead of the three-dimensional mesh structure 3A shown in Figure 5(A).

[0039] In addition, various other structures can be used as the unit structure 4A, such as a rectangular parallelepiped lattice, a diamond lattice, an octahedral lattice, a double pyramidal lattice, or lattices to which various supports are added.

[0040] In the sandal 1A according to the present embodiment, the buffer 13 is made of an elastic material having an elastic modulus of 0.1 MPa to 100 MPa. This configuration allows the buffer 13 to exhibit high buffering performance when a load is applied to the buffer 13 (i.e., when landing or stepping out, etc.), making it possible to effectively distribute foot pressure. To ensure high buffering performance, the material constituting the buffer 13 may have an elastic modulus of 1 MPa to 50 MPa.

[0041] In the sandal 1A according to the present embodiment, each of the plurality of columnar portions 6 has a maximum outer dimension of 1.0 mm or more and 1.8 mm or less in a cross section perpendicular to its extension direction, and the thickness T (see FIG. 4 ) of the buffer portion 13 in a direction perpendicular to the ground surface 12 is 25.0 mm or more. By satisfying these conditions, the sandal can be made to be able to stably support the wearer's foot in a deformed state without bottoming out. Note that in FIG. 4 , for convenience of drawing, the thickest portion of the sole portion 21 serving as the buffer portion 13 is denoted by the symbol T indicating its thickness. However, in the sandal 1A according to the present embodiment, even the thinnest portion of the buffer portion 13 satisfies the above-mentioned condition of a thickness of 25.0 mm or more.

[0042] Here, if the thickness of each of the plurality of columnar portions 6 exceeds the maximum outer dimension within the above-mentioned range, the rigidity of the buffer portion 13 becomes higher than necessary, and the necessary deformability cannot be imparted to the buffer portion 13. On the other hand, if the thickness of each of the plurality of columnar portions 6 is smaller than the maximum outer dimension within the above-mentioned range, the rigidity of the buffer portion 13 decreases significantly, and bottoming out may occur. Furthermore, if the thickness of each of the plurality of columnar portions 6 is smaller than the maximum outer dimension within the above-mentioned range, problems such as poor durability or difficulty in manufacturing by three-dimensional additive manufacturing may arise.

[0043] Furthermore, if the thickness T of the buffer section 13 in the direction perpendicular to the contact surface 12 is less than the above-mentioned range, when a load is applied to the buffer section 13 (i.e., when landing, stepping out, standing, etc.), there will not be enough room for the buffer section 13 to deform, and as a result, there is a high risk of bottoming out.

[0044] These conditions were all derived based on the results of the first and second verification tests described below, and by satisfying these conditions, the sole will not bottom out when worn and will be able to stably support the wearer's feet even in a deformed state, as will be described in more detail later.

[0045] 6 to 8 are schematic diagrams showing a method for manufacturing the sandal shown in Fig. 1, respectively showing the start, middle, and end states of the sandal body formed by three-dimensional additive manufacturing. Next, a specific manufacturing method for manufacturing the sandal 1A according to this embodiment will be described with reference to Figs. 6 to 8.

[0046] As described above, in the sandal 1A according to this embodiment, the sandal body 20 including the sole portion 21 and the belt portion 22 is configured as the shaped object 2 made of a single member fabricated by a three-dimensional additive manufacturing method using a photolithography system. The sandal body 20 can be fabricated using a three-dimensional additive manufacturing device 100 such as those shown in Figures 6 to 8.

[0047] The three-dimensional additive manufacturing device 100 produces a model using a three-dimensional additive manufacturing method based on photolithography. The three-dimensional additive manufacturing method based on photolithography is a manufacturing method that uses a photocurable liquid resin or liquid rubber that hardens when exposed to light of a specific wavelength as the main raw material, and produces a model of a desired shape by sequentially layering hardened portions by irradiating the liquid resin or liquid rubber with light of the specific wavelength. For example, ultraviolet light is used as the light of the specific wavelength, and in this case, ultraviolet-curable resin or rubber is used as the main raw material. The liquid resin or liquid rubber described above as the main raw material is not limited to a one-component type, and may be a two-component type, for example.

[0048] 6 to 8 , the three-dimensional additive manufacturing device 100 includes a light source (not shown), a storage tank 101, a platform 102, and an elevator mechanism 103. The storage tank 101 is a portion for storing raw materials such as liquid resin 200, and the platform 102 is for holding and moving the model 2. The elevator mechanism 103 moves the platform 102 in the vertical direction.

[0049] 6, in the three-dimensional additive manufacturing device 100, first, the platform 102 is moved by the lifting mechanism 103, so that the lower surface of the platform 102 is placed in contact with the liquid surface of the liquid resin 200, etc., and in this state, light of a specific wavelength emitted from the light source is irradiated so as to draw a predetermined pattern near the liquid surface of the liquid resin 200, etc., thereby exposing the liquid resin 200, etc., in a portion located near the liquid surface while adhering to the lower surface of the platform 102, and the layer is cured, forming a first cured layer.

[0050] Next, the platform 102 is moved upward (i.e., in the direction of the arrow DR1 in the figure) by a predetermined amount by the lifting mechanism 103, so that the underside of the first cured layer is placed in contact with the liquid surface of the liquid resin 200, etc., and in this state, light of a specific wavelength emitted from the light source is irradiated so as to draw a predetermined pattern near the liquid surface of the liquid resin 200, etc., thereby exposing the liquid resin 200, etc., in a portion located near the liquid surface, while adhering to the underside of the first cured layer, to harden in a layer, and a second cured layer is formed.

[0051] By repeating the same steps as those for forming the second hardened layer (i.e., the steps of moving the platform 102 and exposing the liquid resin 200, etc.), multiple hardened layers are sequentially stacked downward (i.e., in the direction of the arrow DR2 shown in the figure) as shown in Figure 7, thereby progressing the formation of the sandal body 20. In this process of formation, the formation of the sole portion 21 and the formation of the belt portion 22 are carried out successively.

[0052] 8, after all the portions of the sandal body 20 have been modeled, the platform 102 is lifted further upward by the lifting mechanism 103, and the sandal body 20 is separated from the liquid resin 200 stored in the storage tank 101 and removed from the 3D additive manufacturing device 100. Here, the sandal body 20 after modeling is complete is not yet sufficiently hardened and is in a relatively soft state. Therefore, the removed sandal body 20 is separately washed and heat-treated to fully harden it, and then further washed and dried to complete the production of the sandal 1A.

[0053] As described above, in the manufacturing method of sandal 1A according to this embodiment, sole portion 21 is sequentially layered from the side of ground contact surface 12 along a direction perpendicular to ground contact surface 12 by a stereolithography three-dimensional additive manufacturing method, and then belt portion 22 is sequentially layered. In other words, in the manufacturing method of sandal 1A according to this embodiment, the direction perpendicular to ground contact surface 12 of sandal 1A coincides with the direction in which multiple cured layers are sequentially layered to layer sandal 1A to form sandal 1A (i.e., the direction of arrow DR2 shown in the figure).

[0054] Fig. 9 is a schematic diagram showing another method for manufacturing the sandal shown in Fig. 1. Next, another specific method for manufacturing the sandal 1A according to the present embodiment will be described with reference to Fig. 9.

[0055] 9, in the same manner as the manufacturing method of the sandal 1A according to the present embodiment described above (i.e., the manufacturing method of the sandal 1A described with reference to FIGS. 6 to 8), the other manufacturing method of the sandal 1A according to the present embodiment manufactures the sandal 1A by fabricating the sandal body 20 consisting of a single member using a three-dimensional additive manufacturing apparatus 100 by a three-dimensional additive manufacturing method based on a stereolithography system. However, in the other manufacturing method of the sandal 1A according to the present embodiment, the direction in which the sandal body 20 is additively manufactured is different from that in the manufacturing method of the sandal 1A according to the present embodiment described above.

[0056] Specifically, in another manufacturing method for the sandal 1A according to the present embodiment, the sandal body 20 is sequentially layered along the front-to-back direction from the forefoot portion R1 (see FIGS. 3 and 4, etc.) toward the rearfoot portion R3 (see FIGS. 3 and 4, etc.) by a three-dimensional additive manufacturing method using photolithography. In other words, in this other manufacturing method for the sandal 1A according to the present embodiment, the front-to-back direction of the sandal body 20 coincides with the direction in which the multiple hardened layers are sequentially layered (the direction of the arrow DR2 shown in the figure).

[0057] If another manufacturing method for the sandal 1A according to the present embodiment described above is adopted, it will be necessary to form a support part 2' as shown in Fig. 9 separately from the sandal body 20 so that the relatively soft shape of the sandal body 20 is maintained during molding, due to the relationship between the shape of the sandal body 20 to be molded and the posture (i.e., orientation) of the sandal body 20. This support part 2' is to be cut off and removed from the sandal body 20 after molding of the sandal body 20.

[0058] 10(A) and 10(B) are schematic diagrams showing the state of the sole portion of the sandal shown in FIG. 1 when landing and stepping out, respectively. Next, the performance of the buffer portion 13 of the sandal 1A according to this embodiment will be described with reference to FIGS. 10(A) and 10(B). Note that the belt portion 22 is not shown in FIGS. 10(A) and 10(B).

[0059] As described above, in the sandal 1A according to this embodiment, the sole portion 21 includes the buffer portion 13 configured from a single member made of an elastic material having an elastic modulus of 0.1 MPa or more and 100 MPa or less, the buffer portion 13 is composed of a three-dimensional mesh structure 3A in which a plurality of columnar portions 6 are interconnected, each of which has a three-dimensional lattice structure as a unit structure 4A, and the unit structures 4A are repeatedly arranged in multiple rows, and each of the plurality of columnar portions 6 has a maximum outer dimension (in this embodiment, since each of the plurality of columnar portions 6 is approximately cylindrical, the maximum outer dimension is equal to the diameter) of 1.0 mm or more and 1.8 mm or less in a cross section perpendicular to the extension direction, and the thickness T (see FIG. 4) of the buffer portion 13 in the direction perpendicular to the ground contact surface 12 is 25.0 mm or more.

[0060] By satisfying these conditions, as shown in Figure 10 (A), when landing, a large deformation occurs in the sole part 21 (i.e., the buffer part 13) at the part corresponding to the heel part 304 of the wearer's foot 300, which is the part of the sole part 21 that is subjected to the greatest load (i.e., the part from the rear end side of the midfoot part R2 to the front end side of the rearfoot part R3), and as a result, the upper surface 21a of the sole part 21, which serves as the support surface 11, is displaced toward the lower surface 21b, which serves as the ground contact surface 12, causing the heel part 304 of the wearer's foot 300 to sink.

[0061] At this time, since the cushioning part 13 is sufficiently flexible yet thick, bottoming out (a state in which the sole part 21 deforms upon landing and is compressed to almost its maximum extent, and further deformation does not easily occur) does not occur, the pressure on the wearer's feet is distributed, and the wearer feels a soft feeling when stepping on the shoe.

[0062] Furthermore, compared to the sole portion 21 in the portion corresponding to the heel portion 304 of the wearer's foot 300, the sole portion 21 in the portion corresponding to the arch portion 303 of the wearer's foot 300 does not receive a large load. Therefore, as the sole portion 21 in the portion corresponding to the heel portion 304 of the wearer's foot 300 undergoes a large local deformation, the sunken heel portion 304 of the wearer's foot 300 is held in a state where it is enveloped by the sole portion 21, and the wearer's foot 300 is stably supported even when the sole portion 21 is deformed.

[0063] On the other hand, as shown in Figure 10 (B), when stepping out, a large deformation occurs in the sole portion 21 (i.e., the buffer portion 13) at the portion corresponding to the tread portion 302 of the wearer's foot 300, which is the portion of the sole portion 21 to which the greatest load is applied (i.e., the portion from the rear end of the forefoot portion R1 to the front end of the midfoot portion R2), and as a result, the upper surface 21a of the sole portion 21, which serves as the support surface 11, is displaced toward the lower surface 21b, which serves as the ground contact surface 12, causing the tread portion 302 of the wearer's foot 300 to sink.

[0064] At this time, since the cushioning part 13 is sufficiently thick while being sufficiently flexible, bottoming out does not occur, the wearer's foot pressure is dispersed, and the wearer feels a soft feeling when stepping on the shoe.

[0065] Furthermore, compared to the sole portion 21 in the portion corresponding to the forefoot portion 302 of the wearer's foot 300, the sole portion 21 in the portion corresponding to the toe portion 301 and arch portion 303 of the wearer's foot 300 does not bear a large load. Therefore, as the sole portion 21 in the portion corresponding to the forefoot portion 302 of the wearer's foot 300 undergoes a large local deformation, the sinking forefoot portion 302 of the wearer's foot 300 is held in a state in which it is enveloped by the sole portion 21, and the wearer's foot 300 is stably supported even when the sole portion 21 is deformed.

[0066] Although not shown here, when standing, the sole portion 21 (i.e., the buffer portion 13) undergoes significant deformation in the portions of the sole portion 21 that are subjected to the greatest load, namely, the portions corresponding to the forefoot portion 302 of the wearer's foot 300 and the heel portion 304 of the wearer's foot 300, causing the forefoot portion 302 and the heel portion 304 of the wearer's foot 300 to sink. Even in this case, bottoming out does not occur, and the wearer feels a flexible feeling when stepping on the sole portion 21, and the sunken forefoot portion 302 and the heel portion 304 of the wearer's foot 300 are held in a manner that envelops them, thereby stably supporting the wearer's foot 300.

[0067] This type of comfort when stepping on (wearing) is unique and has never been seen before, and is particularly suitable for recovery or relaxation purposes, such as recovering from fatigue by dispersing foot pressure, supporting the arch of the foot, and supporting the heel against pronation, which is a condition known as heel collapse.

[0068] In this way, the sandal 1A according to this embodiment can be a sandal that does not bottom out when worn and can stably support the wearer's foot even in a deformed state.

[0069] From the viewpoint of ensuring a sufficient deformation margin for the buffer section 13, it is preferable to set the thickness T of the buffer section 13 in the direction perpendicular to the ground surface 12 to 25.0 mm or more as described above, and also to set the space factor of the buffer section 13 to 10% or more and 45% or less. With this configuration, a corresponding space is formed inside the buffer section 13, which promotes the deformation of the columnar section 6 and makes it possible to ensure high deformability.

[0070] Furthermore, if the length of one side of the unit space 5A, which is a polyhedral space occupied by each unit structure 4A, is set to 3.0 mm or more and 20.0 mm or less, it becomes difficult for foreign matter to enter the interior of the buffer section 13, and it becomes possible to prevent the deformability from being hindered by the entry of foreign matter.

[0071] In addition, if a three-dimensional lattice structure is adopted as the unit structure 4A in which all of the multiple columnar portions 6 contained therein extend non-parallel to a direction perpendicular to the ground surface 12, buckling of the columnar portions 6 can be suppressed when a load is applied, which helps to ensure high deformability and prevent bottoming out.

[0072] Furthermore, the maximum outer dimension of each of the plurality of columnar portions 6 in a cross section perpendicular to the extension direction may be the same throughout the entire buffer portion 13, or may be different for each portion of the sole portion 21. In the sandal 1A according to this embodiment, the maximum outer dimension is non-uniform for each portion of the sole portion 21, and specifically, is configured to have a distribution in the range of 1.0 mm to 1.8 mm.

[0073] Fig. 11 is a schematic diagram showing the distribution of thicknesses of the pillars in the buffer part of the sandal shown in Fig. 1. Hereinafter, the distribution of thicknesses of the pillars 6 in the buffer part 13 in the sandal 1A according to the present embodiment will be described with reference to Fig. 11.

[0074] As shown in Figure 11, in the sandal 1A, the thickness of the columnar portion 6 in the region approximately in the center in the front-to-back direction of the forefoot R1, which is the region including the portion of the sole portion 21 serving as the buffer portion 13 that supports the sole of the wearer's foot at the part corresponding to the MP joint (the portion indicated by the symbol MP in the figure), is configured to be smaller than the thickness of the columnar portion 6 in the adjacent region.

[0075] On the other hand, in the region of the sole portion 21 that is approximately the center in the width direction from the rear end of the midfoot portion R2 to the front end of the rearfoot portion R3, which is the region that includes the part that supports the sole of the wearer's heel, the thickness of the columnar portion 6 is greater than the thickness of the columnar portion 6 in the region adjacent to it in the front-to-back direction, and further the thickness of the columnar portion 6 in the regions on both outer sides in the width direction from the rear end of the midfoot portion R2 to the front end of the rearfoot portion R3 is greater than the thickness of the columnar portion 6 in the approximately center region in the width direction.

[0076] When configured in this way, not only can the sole of the wearer's foot at the part corresponding to the MP joint and the sole of the heel be flexibly supported, but the sole of the heel, which requires more stable support, can be held even more stably than the sole of the part corresponding to the MP joint of the wearer, making the sandals not only comfortable to wear but also contributing to the retention of the shape of the sandals.

[0077] Fig. 12 is a graph showing the results of the first verification test, and Fig. 13 is a graph showing the results of the second verification test. Next, with reference to Fig. 12 and Fig. 13, the first verification test and the second verification test, which confirmed the extent to which the deformability and bottoming out of the buffer section 13 are affected when the structure of the buffer section 13 is changed, will be described.

[0078] In both the first and second verification tests, several types of samples with a configuration similar to the buffer section 13 described above were actually prototyped, and these were compressed using a compression testing machine to measure the correlation between their load and strain energy.

[0079] In the first verification test shown in Figure 12, the diameter of the columnar portion included in the unit structure constituting the buffer section was varied, while other conditions were kept the same. The size and shape of the buffer section were a rectangular parallelepiped with a dimension of 35.0 mm in the load application direction and 50.0 mm in both directions perpendicular to the load application direction. The diameters of the columnar portions included in the unit structure were 1.6 mm, 1.4 mm, 1.2 mm, 1.1 mm, 1.0 mm, and 0.9 mm for Verification Examples 1 to 6, respectively.

[0080] Here, when bottoming out occurs in the buffer section, the load that increases with the increase in strain energy becomes significantly larger than the degree of load increase up to that point, and this appears as an inflection point in the load-strain energy curve in the graph shown in Figure 11.

[0081] When examining the results of the first verification test from this perspective, it can be seen that in Verification Example 6, in which the diameter of the columnar portion is 0.9 mm, the inflection point appears earlier (i.e., at a lower strain energy) than in Verification Examples 1 to 5, in which the diameter of the columnar portion is larger than 0.9 mm. The maximum strain energy accumulated in the sole portion upon landing is approximately 1.0 J, but the strain energy at the time the inflection point appears in Verification Example 6 is less than 1.0 J, raising concerns that bottoming out may occur during normal use. In contrast, in Verification Examples 1 to 5, in which the diameter of the columnar portion is 1.0 mm or greater, no inflection point appears at less than 1.0 J, which indicates that bottoming out can be effectively suppressed.

[0082] On the other hand, if the diameter of the columnar portion exceeds 1.8 mm, the rigidity of the buffer portion will increase, which may result in a decrease in flexibility. Therefore, based on the results of the first verification test, it can be understood that by setting the diameter of the columnar portion (i.e., the maximum outer dimension in the cross section perpendicular to the extension direction of each of the above-mentioned multiple columnar portions 6) to 1.0 mm or more and 1.8 mm or less, it is possible to obtain a buffer portion with excellent deformability that does not bottom out when worn.

[0083] In the second verification test shown in Figure 13, the thickness of the buffer section was varied, while the other conditions were kept the same. The size and shape of the buffer section were rectangular parallelepipeds with dimensions of 50.0 mm in both axial directions perpendicular to the load application direction. The thicknesses of the buffer section were 40.0 mm, 35.0 mm, 30.0 mm, 25.0 mm, 20.0 mm, and 15.0 mm for verification examples 7 to 12, respectively. The diameters of the columnar sections included in the unit structures constituting the buffer section were all 1.2 mm.

[0084] When the results of the second verification test were examined, in verification examples 11 and 12, in which the buffer thicknesses were 20.0 mm and 15.0 mm, the strain energy at which the inflection point described above appeared was less than 1.0 J, raising concerns that bottoming out would occur during normal use. In contrast, in verification examples 7 to 10, in which the buffer thickness was 25.0 mm or greater, no inflection point occurred at less than 1.0 J, indicating that bottoming out could be effectively suppressed.

[0085] Therefore, based on the results of the second verification test, it can be understood that by making the thickness of the buffer portion 13 25.0 mm or more, it is possible to create a buffer portion with excellent deformability that does not bottom out when worn.

[0086] In the sandal 1A according to the present embodiment described above, the entire sole portion 21 serving as the footbed portion 10A satisfies the above-mentioned predetermined conditions (i.e., the basic structure of the three-dimensional mesh structure that constitutes it, the elastic modulus of the material that constitutes it, the maximum outer dimension in a cross section perpendicular to the extension direction of each of the multiple columnar portions contained therein, and the thickness in a direction perpendicular to the ground contact surface, etc.), and thereby the entire sole portion 21 is configured as the buffer portion 13. However, it is not necessary that the entire sole portion 21 be configured as the buffer portion 13 that satisfies the above-mentioned predetermined conditions, and only a part of it may be configured as the buffer portion 13.

[0087] Here, since the portions of the sole portion 21 where bottoming out is likely to occur are portions where the load applied to the sole portion 21 is large when landing, stepping out, standing, etc., a suitable effect can be obtained by providing the buffer portion 13 only in such portions or only in part of such portions. Based on this viewpoint, for example, in portions of the sole portion 21 where the load applied is relatively small, such as the portion that supports the toes of the wearer's foot, the configuration can be changed in various ways, such as by making the thickness 25.0 mm or less, or by changing the basic structure of the three-dimensional mesh structure that makes up such portions from that described above.

[0088] As an example, a guideline for the portion of the sole portion 21 where the buffer portion 13 should be placed is that, considering that the total load applied to the sole portion 21 when standing on both feet is approximately 500 N or less and that the pressure at the portion where the highest pressure is applied is approximately 200 kPa, it is possible to adopt a configuration in which the buffer portion 13 is placed only in portions where pressure of 150 kPa or more is frequently applied, or only in portions where pressure of 100 kPa or more is frequently applied.

[0089] In this way, the portion configured as the buffer section 13 by satisfying the above-mentioned predetermined conditions only needs to be provided in at least a part of the sole section 21 as the footbed section 10A, and it is not necessary for the entire sole section 21 to satisfy the above-mentioned predetermined conditions. Note that the second to fourth modified examples described below specifically exemplify cases in which only a part of the sole section 21 is configured as the buffer section 13 in this way.

[0090] 14 is a schematic diagram showing the distribution of column thicknesses in the buffer portion of a sandal according to a first modification. Hereinafter, a sandal 1A1 according to the first modification based on the first embodiment will be described with reference to FIG.

[0091] As shown in Figure 14, the sandal 1A1 of the first modified example differs in configuration from the sandal 1A of the above-mentioned embodiment 1 only in that the thickness distribution of the columnar portion 6 of the buffer portion 13 is different.

[0092] Specifically, in the sandal 1A1 according to the first modified example shown in Figure 14, the thickness of the columnar portion 6 in the region near the rear end of the forefoot portion R1, which is the region including the portion of the sole portion 21 serving as the buffer portion 13 that supports the sole of the wearer's foot at the location corresponding to the MP joint (the portion indicated by the symbol MP in the figure), is configured to be larger than the thickness of the columnar portion 6 in the region adjacent thereto.

[0093] When configured in this way, not only can the sole of the wearer's foot at the part corresponding to the MP joint and the sole of the heel be flexibly supported, but these can also be held stably, making the sandals not only comfortable to wear, but also contributing to the retention of the sandals' shape and making them highly durable.

[0094] Therefore, even when using sandals 1A1 according to the first modified example, it is possible to obtain effects similar to those described in the above-mentioned embodiment 1, and the sandals can be made to be capable of stably supporting the wearer's feet in a deformed state without bottoming out.

[0095] 15 to 17 are schematic cross-sectional views of footbed portions of sandals according to second to fourth modifications, respectively. Sandals 1A2 to 1A4 according to second to fourth modifications based on the first embodiment will be described below with reference to FIGS.

[0096] 15 to 17, the sandals 1A2 to 1A4 according to the second to fourth modifications are configured differently from the sandal 1A according to the above-described embodiment 1 only in that the cushioning portion 13 provided in the footbed portion 10A is located in a different position. More specifically, in the sandal 1A according to the above-described embodiment 1, the entire footbed portion 10A is configured as the cushioning portion 13, but in the sandals 1A2 to 1A4 according to the second to fourth modifications, the cushioning portion 13 is provided only partially in the footbed portion 10A.

[0097] Specifically, in the sandal 1A2 according to the second modified example shown in Figure 15, the buffer portion 13 is provided only in the portion of the footbed portion 10A corresponding to the heel portion 304 of the wearer's foot 300 (i.e., the portion from the rear end of the midfoot portion R2 to the front end of the rearfoot portion R3).

[0098] On the other hand, in the sandal 1A3 according to the third modified example shown in Figure 16, the buffer portion 13 is provided separately and independently in the portion corresponding to the tread portion 302 of the wearer's foot 300 (i.e., the portion from the rear end of the forefoot portion R1 to the front end of the midfoot portion R2) and in the portion of the footbed portion 10A corresponding to the heel portion 304 of the wearer's foot 300.

[0099] In addition, in the sandal 1A4 according to the fourth modified example shown in Figure 17, the buffer portion 13 is arranged so as to extend from the portion of the footbed portion 10A corresponding to the forefoot portion 302 of the wearer's foot 300, through the portion corresponding to the arch portion 303, to the portion corresponding to the heel portion 304 (i.e., from the portion near the rear end of the forefoot portion R1 to the portion near the front end of the rearfoot portion R3).

[0100] In addition, in the sandals 1A2 to 1A4 according to the second to fourth modified examples, the cushioning sections 13 provided therein all satisfy the same conditions as those of the sandal 1A according to the first embodiment described above (the basic structure of the three-dimensional mesh structure that constitutes the cushioning section 13, the elastic modulus of the material that constitutes it, the maximum outer dimensions in a cross section perpendicular to the extension direction of each of the multiple columnar sections 6, the thickness of the cushioning section 13 in a direction perpendicular to the contact surface 12, etc.).

[0101] Therefore, even when sandals 1A2 to 1A4 according to the second to fourth modified examples are used, it is possible to obtain effects similar to those described in the first embodiment above, and the sandals can be made to be capable of stably supporting the wearer's feet in a deformed state without bottoming out.

[0102] 15 to 17, sandals 1A2 to 1A4 according to the second to fourth modifications are exemplified as being configured so that the buffer section 13 is embedded in the footbed section 10A. Specifically, this is based on the assumption that the entire footbed section 10A is composed of a single object 2 produced by a three-dimensional additive manufacturing method using a photolithography system, and the portion corresponding to the buffer section 13 is formed so as to satisfy the above-mentioned conditions, while the portion other than the portion corresponding to the buffer section 13 is formed so as not to satisfy the above-mentioned conditions.

[0103] In this regard, instead of such a configuration, the cushioning section 13 alone may be formed from a single shaped object 2 produced by three-dimensional additive manufacturing, and this may be embedded in a member made of another material (such as a general midsole member) to form the footbed section 10A. Also, the cushioning section 13 does not necessarily have to be embedded in the footbed section 10A, and the upper surface, lower surface, or peripheral surface thereof may be configured so as to be exposed from the footbed section 10A.

[0104] 18 is a schematic diagram illustrating the three-dimensional structure of the buffer portion of a sandal according to a fifth modification. Hereinafter, a sandal 1A5 according to the fifth modification based on the first embodiment will be described with reference to FIG.

[0105] The sandal 1A5 of the fifth modified example differs in configuration from the sandal 1A of the first embodiment described above only in that the buffer section 13 has a different three-dimensional structure.

[0106] Specifically, in the sandal 1A according to the first embodiment described above, the three-dimensional mesh structure 3A constituting the cushioning section 13 is constructed by regularly and continuously repeating unit structures 4A called fluorite lattices, whereas in the sandal 1A5 according to the fifth modified example, as shown in FIG. 18, the three-dimensional mesh structure 3B constituting the cushioning section 13 is constructed by regularly and continuously repeating unit structures 4B in which a central support is added to a rectangular parallelepiped lattice.

[0107] In this case, too, the unit structure 4B consisting of a three-dimensional lattice structure has a three-dimensional shape in which multiple columnar portions 6 extending along a predetermined direction are connected to each other, and the unit space 5B occupied by the unit structure 4B has a hexahedral shape.

[0108] Even when sandals 1A5 according to this fifth variant are used, it is possible to obtain effects similar to those described in the first embodiment above, and the sandals can be made to be capable of stably supporting the wearer's feet in a deformed state without bottoming out.

[0109] <Second Embodiment> Fig. 19 is a perspective view of a shoe according to a second embodiment. Hereinafter, a shoe 1B according to the present embodiment will be described with reference to Fig. 19 .

[0110] As shown in Figure 19, shoe 1B includes a sole 30 and an upper 40. The sole 30 has a generally flat shape overall and constitutes a footbed 10A that supports the wearer's foot. The upper 40 has a bag-like shape that covers the wearer's foot except for the sole, thereby constituting a foot cover 10B that covers the instep of the wearer's foot. The upper 40 is located above the sole 30.

[0111] The sole 30 includes a sole body 31 and an outsole 32, and the outsole 32 is fixed to the underside of the sole body 31 by, for example, adhesive. The underside of the outsole 32 forms the ground contact surface, and the sole body 31 is the part that primarily supports the wearer's foot. The outsole 32 preferably has excellent abrasion resistance and grip, and can be made of, for example, a rubber member.

[0112] The upper 40 has an opening 41 at its top into which the wearer's foot is inserted, and a space is formed inside into which the wearer's foot is inserted when the shoe is being worn. The lower surface of the upper 40 is fixed to the upper surface of the sole body 31, for example, by adhesive, and the inner bottom surface of the upper 40 forms a support surface that supports the sole of the wearer's foot when the shoe is being worn. The upper 40 is made of, for example, woven fabric, knitted fabric, nonwoven fabric, synthetic leather, resin, etc., and for shoes that require particular breathability and lightness, double raschel warp knit fabric made of knitted polyester yarn is used.

[0113] In shoe 1B according to this embodiment, sole body 31 is formed from a single member and is composed of a shaped object 2 produced by a three-dimensional additive manufacturing method using a photolithography system. More specifically, sole body 31 is formed from a three-dimensional mesh structure 3A as shown in FIG. 5(A). As a result, the entire sole body 31 of sole 30 serving as footbed 10A functions as buffer 13. The material of sole body 31 is not particularly limited, but can be the same as the material of sandal body 20 described in the first embodiment.

[0114] Here, the buffer section 13 provided in the shoe 1B according to this embodiment satisfies the same conditions as those described in the above-mentioned embodiment 1 (i.e., the basic structure of the three-dimensional mesh structure that constitutes the buffer section and the elastic modulus of the material that constitutes it, the maximum outer dimension in a cross section perpendicular to the extension direction of each of the multiple columnar sections, the thickness of the buffer section in a direction perpendicular to the ground contact surface, etc.).

[0115] Therefore, in the case of shoe 1B according to this embodiment, it is possible to obtain effects similar to those described in the above-mentioned embodiment 1, and it is possible to provide shoes that do not bottom out and can stably support the wearer's foot in a deformed state.

[0116] <Third embodiment> Fig. 20 is a perspective view of a shoe according to a third embodiment, and Fig. 21 is a schematic cross-sectional view taken along line XXI-XXI shown in Fig. 20. Also, Fig. 22 is an exploded view of the shoe shown in Fig. 20. Below, a shoe 1C according to this embodiment will be described with reference to Figs. 20 to 22.

[0117] 20 to 22, shoe 1C is a sock-like shoe that covers almost the entire wearer's foot (i.e., the area distal to the ankle), and includes a shell 50 and an upper body 60. Both shell 50 and upper body 60 have a bag-like shape.

[0118] The shell 50 includes a sole portion 51 and an outer upper portion 52. The sole portion 51 has a generally flat shape, and its lower surface 51b forms the ground contact surface 12. The outer upper portion 52 stands upright from the periphery of the sole portion 51. An opening 53 is provided in the upper portion of the outer upper portion 52.

[0119] The upper body 60 includes a bottom portion 61 and an inner upper portion 62. The bottom portion 61 has a generally flat shape, and its upper surface 61a forms the support surface 11 that supports the sole of the wearer's foot when the shoe is worn. The inner upper portion 62 stands upright from the periphery of the bottom portion 61. An opening 63 into which the wearer's foot is inserted is provided at the top of the inner upper portion 62.

[0120] The upper body 60 is housed in the shell 50 with its bottom portion 61 placed on the sole portion 51 of the shell 50 and its inner upper portion 62 overlapping the outer upper portion 52 of the shell 50. As a result, in the shoe 1C, the footbed portion 10A that supports the wearer's foot is made up of the sole portion 51 of the shell 50 and the bottom portion 61 of the upper body 60, and the foot cover portion 10B that covers the instep of the wearer's foot is made up of a portion of the outer upper portion 52 of the shell 50 and a portion of the inner upper portion 62 of the upper body 60.

[0121] Since the upper body 60 constitutes the portion that comes into contact with the wearer's foot, it is preferable that it be made of a flexibly deformable material, and it can be made of, for example, woven fabric, knitted fabric, nonwoven fabric, synthetic leather, resin, etc. In particular, as will be described later, if a woven fabric, knitted fabric, nonwoven fabric, etc. made of heat-shrinkable synthetic fiber is used, it can be made to fit the wearer's foot better. Examples of heat-shrinkable synthetic fibers include those containing polyester, polyurethane, etc. as the main component.

[0122] In other words, if the upper body 60 is made of a woven or knitted synthetic fiber fabric, nonwoven fabric, or the like that has heat shrinkability, it is formed into a bag shape in advance, and the last described below is inserted inside and then subjected to a heat treatment.By heat shrinking due to heating, the upper body 60 changes shape so that it adheres closely to the molding surface of the last, and the shape after the change is maintained.

[0123] Therefore, by preparing a last that corresponds to the shape of the wearer's foot and using this to mold the above-mentioned upper body 60, it is possible to manufacture an upper body 60 that fits the wearer's foot. Furthermore, by performing the heat treatment using the above-mentioned last while the upper body 60 is assembled into the shell 50, the upper body 60 will also fit the shell 50, thereby further improving the fit.

[0124] In shoe 1C according to this embodiment, shell 50 is formed from a single member, and is made of a shaped object 2 fabricated by a three-dimensional additive manufacturing method using a photolithography system. Here, sole portion 51 of shell 50 is formed from a three-dimensional mesh structure 3A as shown in FIG. 5A. This allows the entire sole portion 51 serving as footbed portion 10A to function as a shock absorber 13. The material of shell 50 is not particularly limited, but can be the same as the material of sandal body 20 described in the first embodiment.

[0125] Here, the buffer section 13 provided in the shoe 1C of this embodiment satisfies the same conditions as those described in the above-mentioned embodiment 1 (i.e., the basic structure of the three-dimensional mesh structure that constitutes the buffer section and the elastic modulus of the material that constitutes it, the maximum outer dimension in a cross section perpendicular to the extension direction of each of the multiple columnar sections, the thickness of the buffer section in a direction perpendicular to the ground contact surface, etc.).

[0126] Therefore, in the case of shoe 1C of this embodiment, it is possible to obtain effects similar to those described in the above-mentioned embodiment 1, and it is possible to provide shoes that do not bottom out and can stably support the wearer's foot in a deformed state.

[0127] <Fourth embodiment> Fig. 23 is a perspective view of a shoe and an insole provided therein according to a fourth embodiment. Hereinafter, a shoe 1D according to this embodiment will be described with reference to Fig. 23 .

[0128] As shown in Figure 23, shoe 1D includes a sole 70, an upper 40, and an insole 80. The sole 70 has a generally flat shape overall. The upper 40 has a bag-like shape that covers the wearer's foot except for the sole, and is located above the sole 70. The insole 80 has a generally flat shape overall, and is provided in shoe 1D by being inserted inside the upper 40.

[0129] The sole 70 includes a midsole 71 and an outsole 72, and the outsole 72 is fixed to the underside of the midsole 71 by, for example, adhesive. The underside of the outsole 72 forms the ground contact surface, and the midsole 71 is the part that primarily supports the wearer's foot. The midsole 71 is made of, for example, a resin foam material containing a resin material as a main component and a foaming agent and a cross-linking agent as secondary components. The outsole 72 preferably has excellent abrasion resistance and grip, and can be made of, for example, a rubber member.

[0130] The upper 40 has an opening 41 at its top into which the wearer's foot is inserted, and a space is formed inside into which the wearer's foot is inserted when the shoe is being worn. The underside of the upper 40 is fixed to the top surface of the sole body 31, for example, by adhesive. The upper 40 is made of, for example, woven fabric, knitted fabric, nonwoven fabric, synthetic leather, resin, etc., and for shoes that require particular breathability and lightness, double raschel warp knit fabric made of knitted polyester yarn is used.

[0131] The insole 80 is made of a single member and is a shaped object 2 produced by a three-dimensional additive manufacturing method using a photolithography system. The insole 80 has a two-layer structure including a base layer 81 and an upper layer 82, each of which is configured to form a layer, and the upper layer 82 is located above the base layer 81. As a result, the upper surface 82a of the upper layer 82 forms the support surface 11 that supports the sole of the wearer's foot when the insole is worn.

[0132] The base layer 81 is a portion that constitutes the buffer portion 13, as will be described later, and the upper layer 82 is a portion that covers the base layer 81 to improve the feel on the foot. If a liner made of, for example, woven fabric or nonwoven fabric is provided in the insole 80 so as to further cover the upper layer 82, the wearer's foot can be inserted more smoothly into the shoe 1D when worn.

[0133] Here, the base layer 81 is made of a three-dimensional mesh structure 3A as shown in Fig. 5(A). As a result, the base layer 81 functions as the buffer section 13 as described above. On the other hand, the upper layer 82 is made of a sheet-like structure, and the upper layer 82 is provided with a plurality of holes that penetrate along its thickness direction. These holes are provided in the upper layer from the viewpoints of reducing weight and improving the molding accuracy of the insole.

[0134] As described above, the insole 80 is provided in the shoe 1D by being inserted inside the upper 40, and more specifically, the insole 80 is disposed on the inner bottom surface of the upper 40. As a result, in the shoe 1D, the footbed portion 10A that supports the wearer's foot is formed by the sole 70 and the insole 80, and the foot cover portion 10B that covers the instep of the wearer's foot is formed by the upper 40.

[0135] In shoe 1D according to this embodiment, insole 80 is formed from a single member and is composed of a shaped object 2 produced by a three-dimensional additive manufacturing method using a stereolithography system. Of these, base layer 81 of insole 80 is formed from a three-dimensional mesh structure 3A as shown in FIG. 5A as described above. As a result, the sole 70 as the footbed portion 10A and the above-described base layer 81 of insole 80 as a whole function as the cushioning portion 13. The material of insole 80 is not particularly limited, but can be the same as the material of sandal body 20 described in the first embodiment.

[0136] Here, the buffer section 13 provided in the shoe 1D of this embodiment satisfies the same conditions as those described in the above-mentioned embodiment 1 (i.e., the basic structure of the three-dimensional mesh structure that constitutes the buffer section and the elastic modulus of the material that constitutes it, the maximum outer dimension in a cross section perpendicular to the extension direction of each of the multiple columnar sections, the thickness of the buffer section in a direction perpendicular to the ground contact surface, etc.).

[0137] Therefore, in the case of shoe 1D of this embodiment, it is possible to obtain effects similar to those described in embodiment 1 above, and it is possible to provide shoes that do not bottom out and can stably support the wearer's foot in a deformed state.

[0138] <Summary of Contents Disclosed in the Embodiments, etc.> The features disclosed in the above-described first to fourth embodiments and their modifications, etc., can be summarized as follows.

[0139] [Note 1] Footwear having a footbed portion that supports the sole of a wearer's foot and is provided with a ground contact surface, wherein the footbed portion includes a cushioning portion constructed from a single member made of an elastic material having an elastic modulus of 0.1 MPa or more and 100 MPa or less, the cushioning portion is made of a three-dimensional mesh structure in which a unit structure is a three-dimensional lattice structure in which a plurality of columnar portions are interconnected and the unit structure is repeatedly arranged in a plurality of rows, each of the plurality of columnar portions having a maximum outer dimension of 1.0 mm or more and 1.8 mm or less in a cross section perpendicular to the extension direction of the columnar portion, and the thickness of the cushioning portion in the direction perpendicular to the ground contact surface is 25.0 mm or more.

[0140] [Appendix 2] The footwear according to appendix 1, wherein the space factor of the buffer section is 10% or more and 45% or less.

[0141] [Supplementary Note 3] When the polyhedral space occupied by each of the unit structures is referred to as a unit space, the length of one side of the unit space is 3.0 mm or more and 20.0 mm or less.

[0142] [Supplementary Note 4] The footwear according to any one of Supplementary Notes 1 to 3, wherein all of the plurality of columnar portions extend non-parallel to a direction perpendicular to the ground contact surface.

[0143] [Appendix 5] Footwear according to any one of Appendices 1 to 4, wherein the footbed portion has a forefoot portion that supports the toes and forefoot of the wearer's foot, a midfoot portion that supports the arch of the wearer's foot, and a rearfoot portion that supports the heel of the wearer's foot, and the cushioning portion is located in at least the rearfoot portion.

[0144] [Appendix 6] Footwear according to Appendix 5, wherein the cushioning portion is located in the forefoot portion in addition to the rearfoot portion.

[0145] [Appendix 7] The footwear according to Appendix 6, wherein the cushioning portion is positioned across the forefoot portion, the midfoot portion, and the rearfoot portion.

[0146] [Appendix 8] The footwear described in Appendix 6 or 7, wherein the maximum outer dimension of the columnar portion located in a portion included in the rear foot portion is greater than the maximum outer dimension of the columnar portion located in a portion of the cushioning portion adjacent to that portion.

[0147] [Appendix 9] The footwear according to any one of Appendices 6 to 8, wherein the maximum outer dimension of the columnar portion located in a portion of the cushioning section that supports the sole of the wearer's foot corresponding to the MP joint is larger than the maximum outer dimension of the columnar portion located in a portion of the cushioning section adjacent to that portion.

[0148] [Supplementary Note 10] Footwear according to any one of Supplementary Notes 1 to 9, wherein the cushioning portion is made of a single object fabricated by a three-dimensional additive manufacturing method using a photolithography system.

[0149] [Appendix 11] The footwear according to any one of Appendices 1 to 10, wherein the footwear is a sandal, and the buffer portion is provided on the sole of the sandal.

[0150] [Appendix 12] The footwear according to any one of Appendices 1 to 10, wherein the footwear is a shoe, and the shock-absorbing portion is provided on a sole of the shoe.

[0151] [Appendix 13] The footwear according to any one of Appendices 1 to 10, wherein the footbed portion includes a sole and an insole positioned above the sole, and the cushioning portion is provided in the insole.

[0152] <Other Forms, etc.> In the above-described embodiments and their modifications, the three-dimensional mesh structure constituting the buffer section has been described as being composed of a single type of unit structure arranged in a repeated manner, but it is also possible to configure it with different types of unit structures. For example, a portion of the buffer section may be composed of the above-described fluorite lattice, and another portion of the buffer section may be composed of the above-described rectangular parallelepiped lattice with a central support added. When a three-dimensional mesh structure is configured with different types of unit structures, it is preferable that the shape of the structure be continuously changed so that the shape transition along the arrangement direction is smooth.

[0153] Furthermore, in the above-described embodiments and their variations, the cushioning portion provided in the footbed portion has been described as being manufactured by a three-dimensional additive manufacturing method using a photopolymerization method, but it is of course possible to manufacture it by other types of three-dimensional additive manufacturing methods, and it may also be manufactured by methods other than three-dimensional additive manufacturing methods such as injection molding.

[0154] Furthermore, in the above-described embodiments and their modifications, the present invention has been described as being applied to sandals, shoes, and those equipped with insoles, but the present invention can naturally be applied to other types of footwear.

[0155] Furthermore, the characteristic configurations disclosed in the above-described embodiments and their modifications can be combined with each other without departing from the spirit of the present invention.

[0156] As such, the above-described embodiments and their modifications disclosed herein are illustrative in all respects and are not limiting. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0157] DESCRIPTION OF SYMBOLS 1A, 1A1 to 1A5 Sandals, 1B to 1D Shoes, 2 Shaped object, 2' Support portion, 3A, 3A', 3B Three-dimensional mesh structure, 4A, 4A', 4B Unit structure, 5A, 5A', 5B Unit space, 6 Column portion, 10A Footbed portion, 10B Foot cover portion, 11 Support surface, 12 Ground surface, 13 Cushioning portion, 20 Sandal body, 21 Sole portion, 21a Upper surface, 21b Lower surface, 22 Belt portion, 23 Shoe opening, 24 Front opening, 30 Sole, 31 Sole body, 32 Outsole, 40 Upper, 41 Shoe opening, 50 Shell, 51 Sole portion, 51b Lower surface, 52 Outer upper portion, 53 Opening, 60 Upper body, 61 Bottom portion, 61a Upper surface, 62 Inner upper part, 63: shoe opening, 70: sole, 71: midsole, 72: outsole, 80: insole, 81: base layer part, 82: upper layer part, 82a: upper surface, 100: three-dimensional additive manufacturing device, 101: reservoir, 102: platform, 103: lifting mechanism, 200: liquid resin, 300: foot, 301: toe part, 302: tread part, 303: arch part, 304: heel part, R1: forefoot part, R2: midfoot part, R3: rearfoot part.

Claims

1. Footwear comprising a footbed portion that supports the sole of a wearer's foot and is provided with a ground contact surface, wherein the footbed portion includes a cushioning portion constructed from a single member made of an elastic material with an elastic modulus of 0.1 MPa to 100 MPa, wherein the cushioning portion is a three-dimensional mesh structure in which a unit structure is a three-dimensional lattice structure in which a plurality of columnar portions are interconnected and a plurality of such unit structures are repeatedly arranged, wherein each of the plurality of columnar portions has a maximum outer dimension in a cross section perpendicular to its extension direction of 1.0 mm to 1.8 mm, and wherein the thickness of the cushioning portion in the direction perpendicular to the ground contact surface is 25.0 mm or more.

2. The footwear according to claim 1, wherein the space factor of the buffer section is 10% or more and 45% or less.

3. The footwear according to claim 1, wherein, when the polyhedral space occupied by each of the unit structures is referred to as a unit space, the length of one side of the unit space is 3.0 mm or more and 20.0 mm or less.

4. The footwear according to claim 1, wherein all of said plurality of pillars extend non-parallel to a direction perpendicular to said ground surface.

5. Footwear according to claim 1, wherein the footbed portion has a forefoot portion that supports the toes and plantar flexion of the wearer's foot, a midfoot portion that supports the arch of the wearer's foot, and a rearfoot portion that supports the heel of the wearer's foot, and the shock-absorbing portion is located in at least the rearfoot portion.

6. The footwear of claim 5, wherein the cushioning portion is located in the forefoot portion in addition to the rearfoot portion.

7. The footwear according to claim 6, wherein the cushioning portion is positioned across the forefoot portion, the midfoot portion, and the rearfoot portion.

8. The footwear according to claim 6, wherein the maximum outer dimension of the columnar portion located in a portion included in the rear foot portion is greater than the maximum outer dimension of the columnar portion located in a portion of the cushioning portion adjacent to that portion.

9. Footwear as described in claim 6, wherein the maximum outer dimension of the columnar portion located in a portion of the cushioning section that supports the sole of the wearer's foot corresponding to the MP joint is greater than the maximum outer dimension of the columnar portion located in a portion of the cushioning section adjacent to that portion.

10. The footwear according to claim 1, wherein the cushioning portion is made of a single object fabricated by a three-dimensional additive manufacturing method using a photolithography method.

11. Footwear according to any one of claims 1 to 10, wherein the footwear is a sandal, and the shock-absorbing portion is provided on the sole of the sandal.

12. Footwear according to any one of claims 1 to 10, wherein the footwear is a shoe, and the shock-absorbing portion is provided on the sole of the shoe.

13. Footwear according to any one of claims 1 to 10, wherein the footbed portion includes a sole and an insole positioned above the sole, and the shock-absorbing portion is provided in the insole.