Insoles and footwear equipped with them

Abstract

To provide an insole that offers a comfortable fit for the user, improves cushioning and stability while standing, and reduces fatigue while standing, and footwear equipped with such an insole. [Solution] In the insole 42 that constitutes the sole 4 of the footwear 1, a lower layer 43 and an upper layer 44 are laminated together. The lower layer 43 is made of a first rebound elastic material which has relatively lower hardness compared to the upper layer 44, and the upper layer 44 is made of a second rebound elastic material which has relatively higher hardness compared to the lower layer 43 and a higher rebound modulus than the first rebound elastic material.

Description

Technical Field

[0001] The present invention relates to the technology of an insole and footwear provided with the same, and more particularly to the technology of an insole constituting a sole of footwear and footwear provided with the insole.

Background Art

[0002] Conventionally, various insoles for footwear characterized by materials, shapes and three-dimensional structures have been proposed for the purposes of reducing the burden on feet, improving wearing comfort, maintaining the skeletal shape of feet, and preventing lateral sway of the heel. Generally, a sole of footwear is composed of a plurality of components such as an outsole, a midsole, and an insole. Since the upper surface of the insole directly supports the user's foot, the insole itself is also required to have various product functions such as cushioning properties, stability, and wearing comfort (fit).

[0003] By the way, in an environment where a standing posture must be maintained for a predetermined period of time, such as standing work for a long time, the burden on the lower body, centered on the feet, increases with the passage of time. To maintain body balance when standing, muscles such as the soles of the feet, calves, and front thighs are forced into fine tension. As time passes, fatigue substances accumulate in these muscles and blood flow stagnates, causing the feet to feel tight and sluggish.

[0004] In order to reduce such fatigue during standing (reduction of standing fatigue), as a product function of the insole, for example, if cushioning properties are required to alleviate the load applied to the heel and forefoot and reduce the burden on joints and muscles, the insole needs to be formed of a material that is soft to a certain extent. On the other hand, if stability is required to support the foot, prevent unnecessary lateral sway and postural collapse, suppress excessive tension of the lower limb muscle group, and reduce the burden of maintaining balance, conversely, the insole needs to be formed of a hard material.

[0005] Conventional insoles employ a multi-layered structure, where layers of different materials are stacked together, in order to simultaneously achieve multiple product functions that are often conflicting, such as cushioning and stability, as described above.

[0006] As an example of a conventional insole of this type, Patent Document 1 discloses a multilayer structure in which each layer has a different rebound modulus and density, and these are suitably combined and laminated to improve the feeling of hold when the foot is placed inside the footwear and weight is applied, and to enable smoother kicking when transitioning to a push-off motion and push-off after weight is transferred to the toes, thereby improving both comfort and walking performance.

[0007] However, conventional insoles, such as those described in Patent Document 1, primarily consist of a multi-layered structure with a relatively hard lower layer and a relatively soft upper layer. While this certainly improves product functionality during walking and exercise, it does not aim to reduce standing fatigue as described above, and therefore has the problem of not being able to improve both cushioning and stability while standing. Furthermore, since the effect of reducing standing fatigue cannot be felt by the user after wearing the insole for a short period of time, the product functionality of the insole also requires good cushioning, stability, and comfort—a feeling of wearing the insole—that can be immediately perceived upon putting it on. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2024-89877 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, the present invention aims to solve the aforementioned conventional problems by providing an insole and footwear equipped therewith that offer a good fit for the user, improve cushioning and stability while standing, and reduce fatigue while standing. [Means for solving the problem]

[0010] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0011] In other words, in claim 1, the insole constituting the sole of footwear is constructed by laminating a lower layer and an upper layer, wherein the lower layer has a relatively lower hardness compared to the upper layer. Using low-rebound urethane foam with a rebound modulus of less than 15% Formed from a first rebound elastic material, the upper layer has relatively higher hardness compared to the lower layer and a higher rebound modulus than the first rebound elastic material. Using a medium-rebound urethane foam with a rebound modulus of 15% to less than 50%. It is formed from a second rebound elastic material.

[0013] Claim 2 In this case, the thickness of the lower layer is equal to or greater than the thickness of the upper layer.

[0014] Claim 3 In this case, the lower layer and the upper layer each have a thickness of 2.0 mm or more, and the total thickness is 15.0 mm or less.

[0015] Claim 4 In this case, the upper surface of the lower layer and the lower surface of the upper layer are bonded together to form the structure.

[0016] Claim 5 In this case, the footwear comprises an insole as described in claim 1, wherein the insole is detachably laid on the upper surface of the midsole.

[0017] Claim 6In the present invention, the midsole is formed of a material having higher hardness than the first resilient material of the lower layer and the second resilient material of the upper layer.

[0018] Claim 7 comprises an outsole arranged at a lower portion of the midsole and in contact with a road surface, wherein the outsole comprises a sustentaculum tali corresponding portion formed at a position where a central axis vertically overlaps with the sustentaculum tali of a user, a cuboid corresponding portion formed at a position where a central axis vertically overlaps with the cuboid of the user, and a first metatarsal sesamoid corresponding portion formed at a position where a central axis vertically overlaps with the first metatarsal sesamoid of the user, wherein the Listed sustentaculum tali corresponding portion, the cuboid corresponding portion and the first metatarsal sesamoid corresponding portion are formed of a material having higher hardness than other portions of the outsole. Effects of the Invention

[0019] According to the effects of the present invention, the user's foot fit is good, cushioning performance and stability in standing position can be improved, and fatigue in standing position can be reduced. Brief Description of Drawings

[0020] [Figure 1] FIG. 1 is a side view showing the overall structure of an insole according to one embodiment of the present invention and a footwear comprising the same. [Figure 2] FIG. 2 is a perspective view showing the structure of a sole. [Figure 3] FIG. 3 is a bottom view showing the sole surface of the sole. [Figure 4] FIG. 4 is a view showing the sustentaculum tali, cuboid and first metatarsal sesamoid of foot bones viewed from the sole side. [Figure 5] FIG. 5 is a perspective view showing the structure of an insole. [Figure 6] FIG. 6 is a cross-sectional view of the insole. [Figure 7] FIG. 7 is a view showing an evaluation table of the modified Borg scale. [Figure 8] FIG. 8 is a view showing options of the Likert scale. [Figure 9] This figure shows an evaluation table of a modified Borg scale for another embodiment. [Figure 10] This figure shows the change over time in the burden score during the footwear burden test in this embodiment. [Figure 11] This figure shows the results of the subjective evaluation test of the footwear in this embodiment. [Figure 12] This figure shows the results of the foot pressure distribution test for the footwear of this embodiment. [Modes for carrying out the invention]

[0021] Next, a description of the embodiment for carrying out the invention will be given.

[0022] First, the overall configuration of footwear 1 in this embodiment will be outlined below. As shown in Figure 1, the footwear 1 of this embodiment is configured as a symmetrical shoe consisting of a left foot shoe and a right foot shoe, and is composed of an upper 3 that is positioned to allow the foot to be inserted and removed through an opening 2, and a sole 4 which is located below the upper 3 and has anti-slip grooves on its bottom surface. In this embodiment, the left foot shoe and the right foot shoe are formed to be symmetrical and substantially the same shape, so the configuration of the left foot shoe will be described mainly below.

[0023] The upper 3 is integrally formed with a main body 30 that mainly covers the forefoot, midfoot, and part of the rearfoot of the user, an opening 31 that forms the collar 2, and a heel portion 32 that mainly covers the heel of the user's rearfoot. The upper 3 is formed so that the main body 30 covers the front area from the collar 2 to the toes, and the heel portion 32 covers the rear area by surrounding the heel from the side of the collar 2.

[0024] A tongue portion 33 is attached by stitching to the main body portion 30 of the upper 3, extending diagonally upward toward the rear end of the opening 2 and mainly covering the upper surface of the wearer's midfoot. The tongue portion 33 is configured to further expose the opening 2 in the front-to-back direction of the footwear 1.

[0025] The footwear 1 of this embodiment can be given elasticity by using an elastic material for part or all of the upper 3. As the elastic material, for example, known elastic mesh material, knit material, and synthetic leather can be used. As for the material of the upper 3, depending on the purpose and use of the footwear 1, it is possible to appropriately combine materials with different elasticity or different directions of stretch, or to appropriately change the parts and proportions of use of these materials.

[0026] As shown in Figures 1 to 3, the sole 4 constitutes the bottom of the footwear 1 and is made of a lightweight, soft resin material or the like, and is designed to return to its original shape when the external force is applied and then released after being bent. In an unbent state (static state), the sole 4 is configured such that when the footwear 1 is placed on the ground (horizontal surface), the toe and heel portions are separated from the horizontal surface. Specifically, the sole 4 of this embodiment consists of an outsole 40 that contacts the road surface, a midsole 41 disposed on top of the outsole 40, and an insole 42 that is detachably laid on the upper surface of the midsole 41.

[0027] The outsole 40 forms the lower ground engagement surface (bottom surface) of the footwear 1 and is composed of a single element or multiple elements joined together. The outsole 40 is formed using a known elastic material. As the main elastic material of the outsole 40, for example, known resin materials such as ethylene-vinyl acetate copolymer (EVA), polyurethane (PU), thermoplastic elastomer, styrene resin, olefin resin, etc., or known rubber materials such as natural rubber or butadiene rubber can be used, and preferably, a rubber material is used.

[0028] The outsole 40 has a sole surface 40a that is divided into multiple roughly rectangular block sections 40c by multiple grooves 40b. The surface of the block sections 40c has anti-slip grip grooves, grip recesses, etc., which are not shown (see Figure 3).

[0029] The outsole 40 of this embodiment focuses on the structure and function of the sustentaculum tali, a component of the tarsal bones composed of the cuneiform, cuboid, navicular, talus, and calcaneus, and employs a sole structure (three-point support structure) that effectively prevents excessive pronation. As shown in Figures 3 and 4, the outsole 40 of this embodiment is provided with a sustentaculum tali corresponding portion 46 formed in a location corresponding to the position of the user's sustentaculum tali, a cuboid corresponding portion 47 formed in a location corresponding to the position of the user's cuboid, and a first metatarsal sesamoid bone corresponding portion 48 formed in a location corresponding to the position of the user's first metatarsal sesamoid bone.

[0030] The sustentacle tali process corresponding portion 46, the cuboid bone corresponding portion 47, and the first metatarsal sesamoid bone corresponding portion 48 are partitioned by the groove 40b described above, and each is formed in a circular shape when viewed from the base. The sustentacle tali process corresponding portion 46 is formed at a position where its central axis coincides vertically with the sustentacle tali process, the cuboid bone corresponding portion 47 is similarly formed at a position where its central axis coincides vertically with the cuboid bone, and the first metatarsal sesamoid bone corresponding portion 48 is similarly formed at a position where its central axis coincides vertically with the two first metatarsal sesamoid bones.

[0031] The outsole 40 is formed from a material with higher hardness in the sustentacle tali region corresponding portion 46, the cuboid bone corresponding portion 47, and the first metatarsal sesamoid bone corresponding portion 48 than in other areas (areas other than the sustentacle tali region corresponding portion 46, the cuboid bone corresponding portion 47, and the first metatarsal sesamoid bone corresponding portion 48). Specifically, the elastic material of the outsole 40 is preferably a rubber material with a durometer A type hardness in the range of 50 degrees to 70 degrees, and in particular, the sustentacle tali region corresponding portion 46, the cuboid bone corresponding portion 47, and the first metatarsal sesamoid bone corresponding portion 48 is made of a rubber material with a durometer A type hardness in the range of 60 degrees to 80 degrees, which is higher than in other areas.

[0032] In this embodiment, the sole 4 employs the aforementioned sole structure (three-point support structure), supporting the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle tali at the sustentacle cuboid

[0033] The midsole 41 is fixed to the upper part of the outsole 40 and is composed of a single element or multiple elements joined together. The midsole 41 can be formed using a known resilience material. As the resilience material of the midsole 41, for example, foam materials such as ethylene-vinyl acetate copolymer (EVA) or polyurethane (PU), which are known resin materials, or foam materials such as natural rubber or butadiene rubber, which are known rubber materials, can be used. Preferably, EVA foam is used, which is optimized for the lightness, elasticity and stability of the midsole 41.

[0034] The midsole 41 has a wall portion 41b along the periphery of the upper surface 41a on which the insole 42, described later, is laid. The upper 3 described above is fixed to the upper surface 41a, and the sides of the upper 3 are supported by the wall portion 41b. In this way, the footwear 1 of this embodiment has the upper 3 supported by the wall portion 41b of the midsole 41, which improves the overall shape retention of the footwear while suppressing lateral movement of the heel, thereby improving fit and stability.

[0035] The rebound elastic material of the midsole 41 is made of a material with a higher hardness than the insole 42 (lower layer 43 and upper layer 44) described later, and preferably, EVA foam with a durometer E-type hardness in the range of 40 degrees to 70 degrees is used. This is because if the hardness of the rebound elastic material of the midsole 41 is less than 40 degrees, it is too soft and has poor walking stability and shape retention, and if it is greater than 70 degrees, it is too hard and has poor cushioning.

[0036] As shown in Figures 2, 5, and 6, the insole 42 is formed in a substantially flat shape to match the shape of the inner bottom surface of the footwear 1, that is, the shape of the upper surface 41a of the midsole 41. The insole 42 is inserted into and removed from the internal space of the upper 3 through the opening 2 and is detachably laid on the upper surface of the midsole 41.

[0037] The insole 42 in this embodiment includes both the concepts of a midsole and an insole. A midsole is a part of the finished footwear 1, which is assembled during the manufacturing process of the footwear 1 and cannot be removed. An insole is a part that can be attached as a component during the manufacturing process of the footwear 1, or a part that can be attached as an additional component to the finished footwear 1. In other words, the insole 42 in this embodiment may be formed integrally with the footwear 1 (midsole 41) as a midsole, or it may be formed to be detachable from the footwear 1 as an insole. In this embodiment, as an example, the footwear 1 has an insole 42 that is formed as an insole and is detachable from the footwear 1.

[0038] The insole 42 is composed of a lower layer 43, an upper layer 44, and a surface layer 45, and is configured as a multilayer structure in which the lower layer 43, upper layer 44, and surface layer 45 are stacked in order from bottom to top. The lower layer 43 is made of a first rebound elastic material which has relatively lower hardness compared to the upper layer 44 described later, and the upper layer 44 is made of a second rebound elastic material which has relatively higher hardness compared to the lower layer 43 described above and has a higher rebound modulus than the first rebound elastic material.

[0039] As the first resilient material for the lower layer 43, for example, known resin materials such as ethylene-vinyl acetate copolymer (EVA), polyurethane (PU), styrene resin, olefin resin, or foam materials, or known rubber materials such as natural rubber or butadiene rubber, can be used, and preferably urethane foam is used. By using urethane foam as the first resilient material, the insole 42 can be made lighter because it is lighter compared to cases where foam materials such as silicone resin or styrene resin or foamed rubber are used.

[0040] The first resilient material of the lower layer 43 is made of a material with relatively lower hardness compared to the upper layer 44 (the second resilient material), preferably a urethane foam with a durometer E-type hardness in the range of 10 degrees to 30 degrees. This is because if the hardness of the first resilient material is less than 10 degrees, it is too soft and will have poor walking stability and shape retention, and if it is greater than 30 degrees, it is too hard and will have poor cushioning properties.

[0041] The first resilient material of the lower layer 43 is a resilient material with a resilience modulus of less than 15%, preferably a low-rebound urethane foam with a resilience modulus of less than 15%. By using a low-rebound urethane foam with a resilience modulus of less than 15% as the first resilient material, the fit and stability can be improved by the pressure distribution effect.

[0042] As the second resilient material of the upper layer 44, for example, known resin materials such as ethylene-vinyl acetate copolymer (EVA), polyurethane (PU), styrene resin, olefin resin, or foam materials, or known rubber materials such as natural rubber or butadiene rubber, can be used, and preferably urethane foam is used. By using urethane foam as the second resilient material, it is lighter compared to cases where foam materials such as silicone resin or styrene resin or foamed rubber are used, so the insole 42 can be made lighter, and by using the same main material as the first resilient material of the lower layer 43, the adhesion between the lower layer 43 and the upper layer 44 can be improved.

[0043] The second resilience material of the upper layer 44 is made of a material that is relatively harder than the first resilience material of the lower layer 43. Preferably, it is a urethane foam with a durometer E-type hardness in the range of 25 degrees to 50 degrees, which is harder than the first resilience material of the lower layer 43, and the difference in hardness between the two is 5 degrees to 30 degrees. If the hardness of the second resilience material is less than 25 degrees, it is too soft and will have poor walking stability and shape retention, and if it is greater than 50 degrees, it is too hard and will have poor cushioning properties.

[0044] By constructing the lower layer 43 from a material that is relatively less hard (softer) than the upper layer 44, or conversely, the upper layer 44 from a material that is relatively harder (harder) than the lower layer 43, the lower layer 43 provides a cushioning effect that absorbs impact on the soles of the feet, providing a comfortable fit, while the upper layer 44 stabilizes the foot, prevents lateral movement of the heel, and improves the overall shape retention of the insole 42.

[0045] In this embodiment of the insole 42, "relatively high hardness" and "relatively low hardness" in the lower layer 43 and upper layer 44 include a comparison of the average hardness values ​​of the lower layer 43 and upper layer 44. That is, even if the lower layer 43 is relatively low overall and the upper layer 44 is relatively high overall, as a result of optimizing the hardness of the insole 42 (lower layer 43 and upper layer 44) at predetermined locations, the hardness of the lowest part of the upper layer 44 may not be higher than the hardest part of the lower layer 43. Examples of locations where the hardness of the insole 42 can be optimized include the arch area relative to the stepping area and the periphery of the sole relative to the center of the sole.

[0046] The second resilient material of the upper layer 44 is a resilient material with a resilience modulus of 15% or more and less than 50%, preferably a medium-resilience urethane foam with a resilience modulus of 15% or more and less than 50%. Medium-resilience urethane foam refers to a urethane foam having a resilience modulus (15% or more and less than 50%) between low-resilience urethane foam with a resilience modulus of less than 15% and high-resilience urethane foam with a resilience modulus of 50% or more. By using a medium-resilience urethane foam with a resilience modulus of 15% or more and less than 50% as the second resilient material, it is possible to provide appropriate cushioning and comfort by preventing excessive sinking with moderate resilience.

[0047] The surface layer 45 forms the surface of the insole 42 and is made of a known material that has excellent breathability, elasticity, or slip resistance. As the material of the surface layer 45, for example, natural fibers such as natural leather, cloth, paper, rayon and cotton, synthetic fibers including olefin resins, polyester resins, and vinyl alcohol resins such as ethylene-vinyl acetate copolymer (EVA), and other fibers or blends thereof can be used, such as woven fabrics, knitted fabrics or nonwoven fabrics. Furthermore, the material of the surface layer 45 may contain deodorants to enhance odor resistance and antibacterial agents to enhance antibacterial properties, and may be formed as a mesh or mesh-like sheet to enhance breathability.

[0048] In this embodiment, the insole 42 is formed such that the thickness t1 of the lower layer 43 is 2.0 mm or more and 8.0 mm or less, and the thickness t2 of the upper layer 44 is 2.0 mm or more and 8.0 mm or less, preferably the thickness t1 of the lower layer 43 is 3.0 mm or more and 7.0 mm or less, and the thickness t2 of the upper layer 44 is 3.0 mm or more and 7.0 mm or less. In particular, in this embodiment, the thickness t1 of the lower layer 43 is equal to the thickness t2 of the upper layer 44 (t1=t2), or the thickness t1 of the lower layer 43 is greater than the thickness t2 of the upper layer 44 (t1>t2), with each layer having a thickness of 2.0 mm or more and a total thickness of 15.0 mm or less, preferably the thickness of each layer having a thickness of 4.0 mm or more and a total thickness of 10.0 mm or less.

[0049] In environments where one must maintain an upright posture for a predetermined period of time, the impact on the soles of the feet and the upper surface of the insole 42 is not significant. Therefore, as described above, it is preferable to form at least the lower layer 43 and the upper layer 44 to the same thickness, or to form the lower layer 43 relatively thicker (in other words, the upper layer 44 relatively thinner). By optimizing the thickness of the insole 42 (lower layer 43 and upper layer 44) in this way, the lower layer 43 can provide a moderate elasticity and a gentle feel against the foot (cushioning and comfort), while the upper layer 44 can enhance the fit and improve stability while maintaining cushioning.

[0050] Furthermore, since elderly users may have difficulty maintaining their balance, it is preferable that, in order to assist with steady walking, the insole 42 is used for the purpose of assisting elderly people to walk, at least the lower layer 43 and the upper layer 44 be made to the same thickness, or the lower layer 43 be made relatively thicker (in other words, the upper layer 44 be made relatively thinner).

[0051] The thickness t3 of the surface layer 45 is not particularly limited, but is preferably formed to be between 0.1 mm and 1.6 mm. By forming the surface layer 45 to a thickness within the above range, the thickness of the insole 42 can be kept down while effectively preventing deterioration of the upper layer 44 of the insole 42 due to wear.

[0052] The method for manufacturing the insole 42 is not particularly limited, and known methods for manufacturing this type of multilayer insole can be employed. Due to the simplicity of the manufacturing process, a method in which each layer (lower layer 43, upper layer 44, and surface layer 45) is integrally formed by adhesive bonding is preferred. Such bonding methods and bonding processes are not particularly limited and can be appropriately selected depending on the materials of the lower layer 43, upper layer 44, and surface layer 45. For example, methods such as adhesive bonding, heat bonding, ultrasonic bonding, and suturing can be employed.

[0053] Next, examples and comparative examples of the present invention will be described. However, the present invention is not limited to the examples shown below. [Examples]

[0054] <Insoles and footwear used in the examples> For the insoles, sample pieces were prepared using low-rebound urethane foam (hardness (E-type): 20 degrees, rebound modulus: 6%) as the first rebound elastic material for the lower layer, and medium-rebound urethane foam (hardness (E-type): 30 degrees, rebound modulus: 18%) as the second rebound elastic material for the upper layer. Then, as shown in Table 1, sample pieces with different materials (hardness and rebound modulus) and thicknesses were combined, and the pairs of sample pieces were heat-bonded together to create the multilayer insoles used in Examples 1 to 3. In addition, a sample piece made of medium-rebound urethane foam (hardness (E-type): 30 degrees, rebound modulus: 18%) was used as the single-structure insole used in Comparative Example 1, and a sample piece made of EVA foam (hardness (E-type): 50 degrees, rebound modulus: 33%) was used as the single-structure insole used in Comparative Example 2.

[0055] Then, each of the above insoles was laid on the upper surface of the midsole (material: EVA foam, hardness (E type): 60 degrees, rebound modulus: 22%) of a base model footwear (Lilafit RF0504 / manufactured by Hiroshima Kasei Co., Ltd.) to create the footwear of Examples 1-3 and Comparative Examples 1-2.

[0056] [Table 1]

[0057] <Fatigue Level Test> To evaluate the fatigue-reducing effect of the insole during standing, as a product function, the following fatigue test was conducted. The test method involved four adult male subjects wearing the footwear of Examples 1-3 and Comparative Examples 1-2, respectively. While standing and prohibited from walking, and minimizing foot movement, they continuously read documents displayed on a PC screen while sitting on a workbench at elbow height for 60 minutes. Fatigue scores were measured five times, every 15 minutes from the start to the end of the test, using the modified Borg scale (see Figure 7). To minimize physical strain on the subjects, fatigue tests were conducted twice a day, in the morning and afternoon, with at least two hours of rest between sessions.

[0058] In the scoring criteria for the modified Borg scale shown in Figure 7, "0-2" indicates no fatigue in the legs, "3-5" indicates slight heaviness in the legs and mild fatigue, but no problem maintaining an upright position, "6-8" indicates heaviness in the legs and hips and increased fatigue, but still able to continue, and "9-10" indicates very tired legs and considerable difficulty maintaining an upright position.

[0059] The fatigue score was calculated by taking the average of five values ​​measured from the start to the end of the study, and this average was used for all subjects (two measurements per subject).

[0060] <Impression Evaluation Test> To evaluate the immediate perceived comfort of the insole upon wearing, as a product function, the following impression evaluation test was conducted. The test method involved four adult male subjects wearing the footwear of Examples 1-3 and Comparative Examples 1-2, maintaining a standing posture for one minute, and then scoring their evaluation scores based on their first impressions using the Likert scale (see Figure 8).

[0061] The evaluation score was calculated using a 5-point scale for three pre-defined evaluation items: "cushioning (degree of shock absorption and softness on the soles of the feet)," "stability (degree of wobbling and ease of grip)," and "comfort (fit and presence or absence of discomfort)." The evaluation score was the average value for all subjects.

[0062] [Table 2]

[0063] As shown in the results in Table 2, the insoles of Examples 1 to 3, which have a multilayer structure in which the hardness and rebound modulus of the two layers (lower and upper layers) are differed and are suitably combined, were found to have improved foot comfort and to reduce standing fatigue at the same or greater rate compared to Comparative Examples 1 and 2, which have a single structure. In particular, as shown in the test results of Examples 1 and 2, it was confirmed that by forming at least two layers (lower and upper layers) to the same thickness (Example 2), or by forming the lower layer relatively thicker (Example 1), the user's foot comfort is better and standing fatigue can be effectively reduced compared to other insoles (Example 3, Comparative Examples 1 and 2). [Examples]

[0064] <Footwear used in the example> For the footwear, a prototype was manufactured and used as an example, having an outsole, midsole, and insole as a sole with the following configuration. In addition, a known footwear (Dunlop Refined M2011, DM2011 / manufactured by Hiroshima Chemical Co., Ltd.) was used as a comparative example. (a) Outsole: The main elastic material is made of rubber (hardness (Type A): 58 degrees), and the parts corresponding to the sustentaculum talus, the cuboid bone, and the first metatarsal sesamoid bone, which constitute the three-point support structure, are made of rubber (hardness (Type A): 65 degrees) which is harder than the other parts. (b) Midsole: Formed using EVA foam (hardness (E type): 53 degrees) as a rebound elastic material. (c) Insole: The lower layer is formed from low-rebound urethane foam (hardness (E type): 20 degrees, rebound modulus: 6%, thickness: 5.0 mm) as the primary resilience material, and the upper layer is formed from medium-rebound urethane foam (hardness (E type): 30 degrees, rebound modulus: 18%, thickness: 4.0 mm) as the secondary resilience material. The lower and upper layers are heat-bonded together to form a multi-layered insole.

[0065] <Stress assessment test> To evaluate the impact of footwear on the body during standing work, the following stress tests were conducted as part of the product's functionality. The test method involved five adult male subjects wearing the footwear of the example and comparative example, respectively. While standing and prohibited from walking, and keeping their feet as still as possible, they continuously read documents displayed on a PC screen while sitting on a workbench at elbow height for 60 minutes. From the start to the end of the test, the subject was scored seven times at 10-minute intervals using the modified Borg scale (see Figure 9) to measure the burden score for each body part (feet, lower leg, thigh, and hip). Considering the physical burden on the subjects, the burden test was conducted only twice a day, with a break of approximately 2 hours and 30 minutes provided between sessions.

[0066] The burden score was calculated using a nonparametric test (integer rank transformation) based on a total of seven values ​​measured from the start to the end of the study. After integer rank transformation, a two-dimensional analysis of variance was performed on the data with shoe condition and time condition as factors. Post-hoc tests (Wilcoxon rank signed test) were performed in cases where significant results were obtained for main effects and interactions.

[0067] As shown in Figure 10, the footwear of the example showed a significantly lower burden score (Borg score) compared to the footwear of the comparative example, while the burden score of the comparative example tended to increase over time. In particular, the interaction between shoe conditions and time conditions was dominant in the lower leg area (see Figure 10(b)), and multiple comparisons using post-tests showed that the footwear of the comparative example tended to have a higher burden score than the footwear of the example after 30 minutes from the start of measurement. These results confirm that the footwear of the example reduced the subjective physical burden during standing work, and this was particularly noticeable in the feet and lower legs.

[0068] <Subjective Evaluation Test> To evaluate the impression after wearing the footwear as a product function, the following subjective evaluation test was conducted. The test method involved five adult male subjects wearing the footwear of the example and comparative example, maintaining a standing posture for 60 minutes according to the burden test described above, and then measuring the impression score based on the subjective experience of the subjects using the VAS scale (not shown in the figure).

[0069] The impression scores were obtained using the Shapiro-Wilk test for three pre-defined evaluation items: "stability (degree of wobbling and ease of grip)," "cushioning (degree of shock absorption and softness on the soles of the feet)," and "hold (fit and presence or absence of discomfort)." Since the results followed a normal distribution, a paired t-test was performed to test the difference in mean values ​​between shoe conditions.

[0070] As shown in Figure 11, the footwear of the example had significantly higher impression scores, particularly for "stability" and "cushioning," compared to the footwear of the comparative example, confirming that the user's impression after wearing them was positive.

[0071] <Foot pressure distribution test> To quantify the foot pressure distribution while standing as a product function of footwear and to evaluate the foot pressure distribution effect based on the tendency of pressure concentration and dispersion, the following foot pressure distribution tests were conducted. The test method involved having three adult male subjects wear the footwear of the example and comparative example, respectively, and measuring the foot pressure distribution while standing using a foot pressure measurement system (F-Scan II / manufactured by Nitta Corporation).

[0072] The effectiveness of foot pressure distribution is evaluated by visually comparing the load conditions of the same subject obtained from foot pressure distribution measurements, as well as by measuring the load area (cm²). 2 The percentage increase or decrease in load area and heel load (kgf) was calculated. The average values ​​for load area and heel load were used for all subjects.

[0073] As shown in Figure 12, in the example footwear, the foot pressure spread to the midfoot, and it was confirmed that the load distribution was promoted compared to the comparative footwear. In addition, the load area of ​​the example footwear was 102.1 cm². 2 The heel load was 14.4 kgf, and the load area of ​​the comparative example footwear was (90.8 cm²).2 Compared to the load on the heel (16.3 kgf), the load area increased by 11.1% and the heel load decreased by 11.7%, suggesting that the pressure distribution effect during standing is improved in the footwear of the example.

[0074] As described above, the insole 42 of this embodiment is an insole 42 that constitutes the sole 4 of the footwear 1, and is constructed by laminating a lower layer 43 and an upper layer 44. The lower layer 43 is made of a first rebound elastic material which has relatively lower hardness compared to the upper layer 44, and the upper layer 44 is made of a second rebound elastic material which has relatively higher hardness compared to the lower layer 43 and a higher rebound elastic modulus than the first rebound elastic material. As a result, the user's foot fit is good, and the cushioning and stability when standing are improved, thereby reducing fatigue when standing.

[0075] In other words, the insole 42 of this embodiment has a multilayer structure formed by suitably combining a lower layer 43 and an upper layer 44 with different hardness and rebound modulus. The design function of the insole 42 is that, mainly through the action of the lower layer 43, a foam material with appropriate elasticity can be used to provide a gentle feel and cushioning, and mainly through the action of the upper layer 44, an effective pressure distribution effect can be exerted to improve the fit and stability while maintaining cushioning. In this way, the complementary action of the lower layer 43 and the upper layer 44 can provide a good fit, including cushioning, stability, and comfort when wearing the footwear 1, while also providing an excellent fatigue reduction effect.

[0076] In particular, in this embodiment, the insole 42 uses a low-rebound urethane foam with a rebound elasticity of less than 15% as the first rebound elastic material, and a medium-rebound urethane foam with a rebound elasticity of 15% or more and less than 50% as the second rebound elastic material. As a result, the low-rebound urethane foam effectively improves fit and stability through its pressure distribution effect, while the medium-rebound urethane foam prevents excessive sinking with its appropriate rebound properties, effectively providing suitable cushioning and comfort.

[0077] Furthermore, in this embodiment, the insole 42 has a lower layer 43 with a thickness t1 equal to or greater than the upper layer 44 with a thickness t2, and each layer has a thickness of 2.0 mm or more, with a total thickness of 15.0 mm or less. Therefore, in environments where a standing posture must be maintained for a predetermined period of time, the impact on the soles of the feet and the upper surface of the insole 42 is not significant. By optimizing the thicknesses of the lower layer 43 and upper layer 44 in this way, the fit is enhanced, providing superior cushioning and stability, while also effectively providing a gentle feel (cushioning and comfort) with appropriate elasticity.

[0078] Furthermore, the footwear 1 of this embodiment includes, as a sole 4, the insole 42 described above, a midsole 41 formed from a material with higher hardness than the first resilient material of the lower layer 43 and the second resilient material of the upper layer 44, a taliating process corresponding portion 46 formed at a position where its central axis coincides vertically with the user's taliating process, a cuboid bone corresponding portion 47 formed at a position where its central axis coincides vertically with the user's cuboid bone, and a first metatarsal sesamoid bone corresponding portion 4 formed at a position where its central axis coincides vertically with the user's first metatarsal sesamoid bone. The outsole 40 includes 8, and the talar process corresponding portion 46, the cuboid bone corresponding portion 47, and the first metatarsal sesamoid bone corresponding portion 48 are formed from a material with higher hardness than other parts. As a result of the mutually complementary synergistic effects between the midsole 41 and the insole 42, and the mutually complementary synergistic effects between the outsole 40, midsole 41, and insole 42, the footwear 1 can exhibit excellent cushioning, stability, and comfort when worn, especially when standing, while also providing a superior fatigue reduction effect.

[0079] Furthermore, the configuration of the footwear 1 and insole 42 is not limited to the embodiments described above, and various modifications are possible as long as they do not depart from the objective of the present invention.

[0080] In other words, although the insole 42 of the above-described embodiment was described as having a multilayer structure formed by stacking a lower layer 43, an upper layer 44, and a surface layer 45, the structure of such an insole 42 is not limited to this. For example, the surface layer 45 may be omitted, resulting in a multilayer structure consisting of only two layers, a lower layer 43 and an upper layer 44. Alternatively, the lower layer 43 or the upper layer 44 may be further composed of multiple layers.

[0081] Furthermore, although the footwear 1 in the above-described embodiment has been described as having a tongue portion 33 on the main body portion 30, the shape of the footwear 1 is not limited to this, and may be configured as, for example, hands-free footwear without a tongue portion 33 or shoelaces. [Explanation of Symbols]

[0082] 1. Footwear 2. Opening 3 Upper 4 soles 40 Outsole 40a sole surface 40b Groove 40c block section 41 Midsole 41a Top side 41b Wall section 42 Insoles 43 Lower part 44 Upper Management 45 Surface layer part 46. ​​Mounting distance projection corresponding part 47. Cuboid bone corresponding section 48. Corresponding part of the first metatarsal sesamoid bone

Claims

1. In the insole that makes up the sole of footwear, It is constructed by stacking the lower and upper layers, The lower layer is formed from a first resilient material using low-rebound urethane foam, which has relatively lower hardness compared to the upper layer and a rebound modulus of less than 15%. The upper layer is formed from a second rebound elastic material which has a relatively higher hardness compared to the lower layer and a rebound elastic modulus higher than that of the first rebound elastic material, using a medium-rebound urethane foam with a rebound elastic modulus of 15% or more and less than 50%. An insole characterized by the following features.

2. The insole according to claim 1, wherein the thickness of the lower layer is equal to or greater than the thickness of the upper layer.

3. The insole according to claim 1 or claim 2, wherein the lower layer and the upper layer each have a thickness of 2.0 mm or more, and the total thickness is 15.0 mm or less.

4. The insole according to claim 1 or claim 2, formed by bonding the upper surface of the lower layer to the lower surface of the upper layer.

5. Footwear comprising the insole described in claim 1, Footwear characterized in that the insole is detachably laid on the upper surface of the midsole.

6. The footwear according to claim 5, wherein the midsole is formed from a material with a higher hardness than the first resilient material in the lower layer and the second resilient material in the upper layer.

7. The midsole has an outsole that contacts the road surface at its lower part, The aforementioned outsole is It includes a portion corresponding to the sustentacle tali, formed at a position where its central axis coincides vertically with the sustentacle tali of the user; a portion corresponding to the cuboid bone, formed at a position where its central axis coincides vertically with the user's cuboid bone; and a portion corresponding to the first metatarsal sesamoid bone, formed at a position where its central axis coincides vertically with the user's first metatarsal sesamoid bone. The footwear according to claim 5 or 6, wherein the portion corresponding to the tali process, the portion corresponding to the cuboid bone, and the portion corresponding to the first metatarsal sesamoid bone are formed from a material that is harder than the other parts of the outsole.

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