Shoe

Abstract

To provide a shoe improved in flexibility without impairing abrasion resistance and gripping performance.SOLUTION: This shoe is provided with an outsole and a midsole made of synthetic resin foam, and has an exposed part not covered with the outsole in the middle foot part of the lower surface of the midsole, and the midsole has a vertically long recessed part in the exposed part, and has a vertical groove from the middle foot part to the front foot part of the upper surface. A transverse groove may be provided in the forefoot portion of the upper surface of the midsole.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The shoe of the present invention relates to a shoe having a sole including an outsole and a midsole made of a synthetic resin foam. [Background technology]

[0002] Synthetic resin foam is used in the soles of shoes to reduce fatigue when worn and improve cushioning. For example, in the case of shoes with a sole consisting of an outsole and a midsole, the outsole is made of natural rubber, synthetic rubber, or the like, which has excellent abrasion resistance and grip, while the midsole is made of synthetic resin foam such as ethylene vinyl acetate copolymer (EVA), polyurethane, or polyvinyl chloride. Furthermore, in order to impart flexibility to shoes, an outsole is not provided over the entire surface of the midsole, but is provided only in the forefoot and rearfoot areas, which require abrasion resistance and grip when in contact with the ground, and the midsole is exposed in the midfoot area. By exposing the midsole without being covered by the outsole, the flexibility of the synthetic resin foam that forms the midsole is demonstrated, making it possible to impart flexibility to the shoes.

[0003] Additionally, it is known that flexibility can be improved by providing a recess on the exposed surface of the midsole (see Patent Document 1). However, the recesses formed on the exposed surface of the midsole bend due to the weight of the wearer when the shoe touches the ground, and are therefore difficult to follow, for example, the movement of the foot within the shoe. Furthermore, because shoes require grip and wear resistance, at least the forefoot and rearfoot portions of the midsole are covered with an outsole, which presents the problem of making it difficult to provide grooves all the way to the forefoot portion of the midsole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-333705 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above problems, the present invention aims to provide a shoe with improved flexibility without compromising wear resistance or gripping ability. [Means for solving the problem]

[0006] In other words, the present invention solves the above-mentioned problems by providing a shoe that includes an outsole and a midsole made of synthetic resin foam, and has an exposed portion in the midfoot area on the underside of the midsole that is not covered by the outsole, and the midsole has a vertically elongated recess in the exposed portion and a vertical groove on the upper surface extending from the midfoot area to the forefoot area. [Effects of the Invention]

[0007] The shoes of the present invention have a longitudinal recess in the exposed part of the midfoot on the underside of the midsole, and further have longitudinal grooves on the upper surface of the midsole from the midfoot to the forefoot, thereby ensuring wear resistance and grip while also providing excellent flexibility from the midfoot to the forefoot. Furthermore, since both the longitudinal recesses and longitudinal grooves extend in the longitudinal direction of the shoe, the shoe has excellent flexibility even in cases where the load is uneven between the left and right sides, such as during repeated movements, cornering, or jump landing. Furthermore, by forming grooves on the upper surface of the midsole close to the sole of the foot, shoes that fit the movement of the foot better can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view of the outer instep side of a shoe for a left foot according to an embodiment of the present invention. [Figure 2] 1 is a bottom view of a shoe for a left foot according to an embodiment of the present invention. [Figure 3] FIG. 1 is a plan view of a sole structure for a left foot in one embodiment of the present invention. [Figure 4] FIG. 10 is a plan view of a sole structure for a left foot according to another embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the present invention, the upper surface and the lower surface refer to the side of the shoe that faces the upper part of the shoe, and the lower surface refers to the side that comes into contact with the ground. Furthermore, in the shoe of the present invention, the portion corresponding to the metatarsals in the front-to-back direction is referred to as the midfoot, the portion from the midfoot toward the toes in the front-to-back direction is referred to as the forefoot, and the portion from the midfoot toward the heel is referred to as the rearfoot. The forefoot generally corresponds to the phalanges, and the rearfoot generally corresponds to the tarsal bones. When the front-to-back length of the shoe is taken as 100%, the midfoot is a region parallel to a line perpendicular to the center line La, extending approximately 30% to 80% from the tip of the shoe. Similarly, the forefoot is a region extending approximately 0% to 30% from the tip of the shoe, and the rearfoot is a region extending approximately 80% to 100% from the tip of the shoe. The center line La refers to the line connecting the rearmost part of the heel and the tip of the longest toe (tip of the second toe).

[0010] An embodiment for carrying out the present invention will be described below with reference to the drawings. As shown in FIG. 1, a shoe 100 of the present invention has a sole including an outsole 10 and a midsole 20 made of a synthetic resin foam. In this specification, the outsole 10 and the midsole 20 together are also referred to as a sole structure.

[0011] [Outsole] The shoe 100 of the present invention is provided with an outsole 10 at least in the forefoot and rearfoot. By providing the outsole 10 in the forefoot and rearfoot, the shoe 100 can be provided with wear resistance and gripping properties. The forefoot and rearfoot may be entirely or partially covered with the outsole 10. The outsole 10 may also be provided on part of the midfoot, as long as it does not impede the flexibility of the midsole 20, which will be described later. The outsole 10 is preferably made of natural or synthetic rubber, although there are no particular restrictions on the material as long as it is abrasion-resistant and provides grip. In the case of synthetic rubber, for example, a member made of a material containing a rubber material as the main component and a plasticizer, a reinforcing agent, and a cross-linking agent as secondary components is used.

[0012] [Midsole] The shoe 100 of the present invention includes a midsole 20 made of a synthetic resin foam. As the synthetic resin foam that forms the midsole 20, various foams can be used, such as ethylene vinyl acetate copolymer, polyurethane resin, polyvinyl chloride resin, etc., but ethylene vinyl acetate copolymer is preferred from the standpoints of lightness, elasticity, and environmental friendliness. The synthetic resin foam preferably has a Type C hardness of 40 to 70 as measured in accordance with JIS K 6253. If the hardness is less than 40, the hardness is insufficient and the foot tends to lack stability when in contact with the ground. If the hardness exceeds 70, the midsole 20 becomes too hard and does not easily deform in response to changes in load or foot movement, making it difficult to obtain the effects of forming grooves on the lower and upper surfaces, as described below.

[0013] The shoe 100 of the present invention has an exposed portion 21 formed in the midfoot portion, where the lower surface of the midsole 20 is not covered by the outsole 10. The exposed portion 21 has a longitudinally elongated recess 22 formed therein. The provision of the vertically elongated recess 22 makes it easier for the shoe 100 to flex when weight is applied. In addition, it also makes it easier for the shoe 100 to flex when different weights are applied to the inside and outside of the width direction of the shoe 100, such as during repetitive exercise, running around curves, or landing after a jump. The longitudinally elongated recess 22 is formed along the center line La. The vertically elongated recess 22 has a vertical length of 70 to 130 mm (30 to 60% of the total length of the shoe 100), and is not limited as long as the vertical length is greater than the horizontal width, but it is preferable that the vertical length: horizontal width ratio is approximately 2 to 20:1. The width of the vertically elongated recess 22 may vary along the length, in which case the width of the widest part is defined as the width of the vertically elongated recess 22. Furthermore, the shape of the elongated recess 22 is not limited, but is preferably curved toward the medial instep. In ideal walking (so-called sideways walking), the heel touches the ground, and weight moves from the heel along the lateral side of the instep toward the little toe near the MTP joint, and finally to the big toe, where it pushes off the ground. Therefore, the weight moves in a curve toward the medial instep when touching the ground. By making the curve of this weight movement similar to the shape of the vertical groove, the flexibility of the shoe 100 can be maximized.

[0014] The depth of the elongated recess 22 is preferably 5 to 50% of the thickness of the midsole 20, where 100% is the thickness of the midsole 20. If the depth is less than 5%, the flexibility tends to be insufficient. If the depth exceeds 50%, the groove portion becomes thin, and it tends to be difficult to ensure the mechanical properties of the midsole 20. The depth of the recess 22 may vary stepwise along the length and / or width, or may be formed in a cone shape. For example, as shown in Fig. 2, the recess 22 may be formed by dividing it into a first recess 22a, a second recess 22b, and a third recess 22c. In this case, the depth of the recess 22 refers to the depth of the deepest part. The elongated recess 22 may have a protrusion 23 whose height is smaller than the depth of the elongated recess 22. In Fig. 2, the second recess forms the protrusion 23. The presence of the protrusion 23 has the effect of stabilizing the shape of the sole structure.

[0015] The upper surface of the midsole 20 is provided with longitudinal grooves 24 extending from the midfoot portion to the forefoot portion. The presence of the longitudinal grooves 24 makes it easier for the shoe 100 to bend when weighted by the wearer, and also makes it easier for the midsole 20 to deform in accordance with the movement of the foot inside the shoe 100 . The recess 22 cannot be extended to the forefoot because the forefoot is covered by the outsole 10, but the longitudinal groove 24 is formed from the midfoot to the forefoot, so the shoe 100 of the present invention has significantly improved flexibility due to the synergistic effect of the recess 22 and the longitudinal groove.

[0016] The width of the longitudinal grooves 24 is preferably 1 to 5 mm. If the width is less than 1 mm, it becomes difficult for the shoe to flex in response to foot movement. On the other hand, if the width exceeds 5 mm, even if an insole (described later) is provided, the presence of the longitudinal grooves 24 may be felt on the sole of the foot depending on the thickness and material of the insole, and the shoe may feel uncomfortable on the foot. The width of the longitudinal grooves 24 may vary along the lengthwise direction, in which case the width of the widest part is defined as the width of the longitudinal grooves 24. The depth of the longitudinal grooves 24 is preferably 2 to 6 mm. If the depth is less than 2 mm, it becomes difficult for the midsole 20 to flex in response to the movement of the foot. On the other hand, if the depth exceeds 6 mm, it tends to become difficult to ensure the mechanical properties of the midsole 20.

[0017] The longitudinal grooves 24 are formed along the center line. The shape of the longitudinal grooves 24 may be linear or curved, but for the same reasons as the recesses 22 described above, an inward curve is preferred. Furthermore, by aligning the inclination directions of the recesses 22 and the longitudinal grooves 24, the recesses 22 and the longitudinal grooves 24 work together to flex the shoe 100 during a series of movements from landing to pushing off, which is preferable.

[0018] In addition to the longitudinal grooves 24, lateral grooves 25 may be provided in the forefoot portion of the upper surface of the midsole 20. Providing lateral grooves 25 in the forefoot portion of the upper surface is preferable because it allows the midsole 20 to more easily follow the movement of the toes. The lateral groove 25 may be one or more. There are no limitations on the length of the lateral groove 25, but in order to maintain the mechanical strength of the midsole 20, it is preferable to provide the lateral groove 25 in the center in the width direction, avoiding a distance of about 10 mm from both ends in the width direction. The shape of the lateral grooves 25 may be straight or curved, but a straight shape is preferable because it is easier to bend.

[0019] The shoe 100 of the present invention is preferably provided with an insole. By providing the insole, the presence of the longitudinal grooves 24 of the midsole 20 is not felt when wearing the shoe, and the shoe feels good on the foot. The thickness of the insole is preferably 2 to 10 mm. If it is less than 2 mm, the effect of providing the insole is less likely to be achieved. If it exceeds 10 mm, the movement of the wearer's foot is less likely to be transmitted to the midsole 20, and the desired flexibility tends to be less likely to be achieved.

[0020] In this way, the shoe 100 of the present invention has a recess 22 in the exposed portion 21 of the midfoot of the midsole 20, and further has longitudinal grooves 24 on the upper surface of the midsole 20 from the midfoot to the forefoot, thereby ensuring wear resistance and grip while also providing excellent flexibility from the midfoot to the forefoot. Furthermore, since the recesses 22 and longitudinal grooves 24 are both grooves that extend in the vertical direction, they have excellent flexibility even when the load is unevenly distributed between the left and right sides, such as during repeated movements, cornering, or jump landings. Furthermore, by forming grooves on the upper surface of the midsole close to the sole of the foot, it is possible to provide a shoe 100 that fits the movement of the foot better.

[0021] The above describes the shoe 100, which is one embodiment of the present invention. In the above description, the shoe 100 is provided with an upper 30 that covers the entire instep, but the present invention is not limited to this. The shoe 100 of the present invention also includes shoes with an upper that covers at least a portion of the instep, such as sandals that cover a portion of the instep, and boots or runners that cover above the instep, as long as they have the above-described sole structure. [Explanation of symbols]

[0022] 10 Outsole 20 Midsole 21 Exposed part 22 recess 23 Convex part 24 Vertical grooves 25 Yokomizo 30 Upper 100 shoes La center line

Claims

1. A shoe comprising an outsole and a midsole made of a synthetic resin foam, the shoe having an exposed portion at a midfoot portion on the underside of the midsole that is not covered by the outsole, The shoe is characterized in that the midsole has a longitudinal recess in the exposed portion and has longitudinal grooves on the upper surface from the midfoot portion to the forefoot portion.

2. 2. The shoe according to claim 1, wherein the midsole has a lateral groove in the forefoot portion on the upper surface thereof.

3. 3. The shoe according to claim 1, wherein the longitudinally elongated recess has a protrusion whose height is smaller than the depth of the longitudinally elongated recess.

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