JPH0311762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a midsole that can enhance running functionality and improve moldability.

In recent years, the soles of footwear have changed to sponge soles in order to reduce the impact on the feet when driving on stone roads, concrete paved roads, etc., and thicker sponge soles are now being worn depending on the function. In such soles, the outsole is either a solid body or a sponge layer with good wear resistance, and one or an appropriate number of sponge layers with good cushioning properties are inserted between the outsole and the cover. This layer is called midsole. This mid-sole requires a certain degree of hardness, is quite thick, and requires a bending force that can resist the repulsive force of the cushion layer itself at the stepping part, which places an extra load on the wearer's feet. I felt fatigue in my feet and the feeling of wearing them was impaired. In addition, mid soles are made up of layers of different types and colors, and especially when a sponge layer with low hardness and good cushioning properties is layered to reduce weight, the outer wall surface of that layer is exposed as it is. Because of this, the compressive strain is large, and in addition, the fatigue is severe, and the cushioning property decreases significantly over a short period of time, impairing the feeling of wearing, and the poor shape retention promotes lateral vibration, impairing driving functionality. It was making me regress.

In view of the current situation, the present invention combines a polyester urethane outer layer foam and a resilient inner layer foam, thereby combining the superior breaking strength of the polyester urethane outer layer foam. A running function with good shape retention and moldability that effectively takes advantage of the low compression set and good recovery power, as well as the cushioning properties and lightness of the elastic inner layer foam. The purpose is to provide a midsole with excellent properties.

The present invention consists of at least two elastic inner layer foam 1 and an outer layer foam 2 made of polyester urethane, which are attached between the outsole and the shoe cover, and these polymer foams 1 and 2 are It has a contour that almost follows the outsole, and a notch is provided on both sides of the stepping portion of the outer layer foam 2 and/or on the outer side of the heel, and the inner layer foam is disposed in this notch. The above object is achieved by providing a midsole characterized by being filled with one protrusion 3.

The midsole of the present invention has the above-mentioned structure, and the polyester urethane outer layer foam 2 and the elastic inner layer foam 1 are made of materials with different hardnesses in combination, so that there is a smooth surface between each part. A large difference in hardness can be achieved. The hardness of the outer layer foam 2 is in the range of 25 to 80 degrees as measured by Asker hardness tester C type (the same applies hereafter), and the hardness of the inner layer foam 1 is in the range of 20 to 60 degrees, and the average specific gravity of the inner layer foam 1 is 25 to 80 degrees. is 0.05
~0.30, and the average specific gravity of the outer layer foam 2 is in the range of 0.20 to 0.60. By selecting and combining members from this range, the hardness of appropriate parts such as the stepping part and the central part can be reduced, thereby reducing the weight. This midsole is attached between the outsole and the cover, and its lower surface is formed to follow the contour of the upper surface of the outsole, and the upper surface is formed to follow the contour of the lower surface of the cover. Examples of the inner layer foam 1 include foams of polyolefin resins such as polyethylene, ethylene-vinyl acetate copolymer (EVA), rubber, and mixtures thereof. The polyester urethane foam of the outer layer foam 2 is made of diisocyanates such as 4,4-diphenylmethane diisocyanate and 4,4-dicyclohexylmethane diisocyanate, glycols such as ethylene glycol and 1,4-hexanediol, adipate-based polyethylene adipate, Poly(1,4-butylene adipate), poly(1,6-
This is a urethane foam obtained by reacting a polyester diol such as hexane adipate.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view thereof. The inner layer foam 1 is made of foamed EVA with a hardness of 35 degrees and an average specific gravity of 0.1 to 0.15, and the outer layer foam 2 is
Polyester foam urethane having a hardness of 55 degrees and an average specific gravity of 0.4 to 0.5 is used, and the inner layer foam 1 is covered with the outer layer foam 2. In this embodiment, an appropriate number of protrusions 3 are provided on both sides of the stepping part of the inner foam 1 and on the outer surface of the heel, and the outer end surfaces of the protrusions 3 match the contour end surfaces of the outer foam 2. It is formed like this. In addition, a curved part 4 with a concave shape toward the center is provided from the inner surface of the heel part to the arch of the inner layer foam 1, and the contour width of the outer layer foam 2 is made larger than the other contour widths in proportion to this curved part 4. . Inner layer foam 1
A suitable number of protrusions 3 provided on both sides of the treading part and the outer surface of the heel are further extended, and the extended parts of the protrusions 3 are formed by molding the upper mold and the lower mold. The liquid polyurethane material that will become the outer layer foam 2 is injected into the holding hole communicating with the recess to be formed, and the liquid polyurethane material is injected to cause a foam hardening reaction. Then, the inner layer foam 1 is cut out to form a midsole made of polymer foam in which the end surfaces of the protrusions 3 of the inner layer foam 1 are exposed on the contoured end surfaces.

In another embodiment of the present invention, as shown in FIG. 3 (plan view) and FIG. The outer foam layer 2 on the upper surface of the section 3 may be removed, and the inner foam layer 1 may directly protrude to the surface so that the inner layer foam 1 fills this removed portion. The color tone of this protrusion 3 may be matched to the color tone of the inner layer foam 1, or simply only the protrusion 3 or its outer end surface is red.
Color it blue, yellow, etc. Further, the shape of the outer end surface of the protrusion 3 is formed into an appropriate shape such as a circle, a triangle, or a rhombus depending on its function.

As described above, in the midsole of the present invention, the entire surface of the inner layer foam 1 made of foamed EVA that is almost similar to the bottom shape, or almost the entire surface excluding the top surface, is covered with the outer layer foam 2 made of polyester-based urethane. By joining, foamed EVA has the disadvantage that it does not have the breaking strength and is damaged by a slight external force, and polyester-based urethane, especially low-foamed polyurethane, has poor weight reduction and is difficult to use in thick parts such as the heel. Eliminating disadvantages such as sink marks, foamed EVA combines the advantages of cushioning and light weight with polyester urethane's high breaking strength, low compression set, and good recovery power. was able to demonstrate this effectively. By reducing the thickness of the stepped portion of the outer foam layer 2, flexibility can be increased and bending resistance to the wearer's feet can be alleviated. In addition, even if the heel part of the inner foam layer 1 is thicker, it is covered and bonded with the outer foam layer 2, which has a harder hardness than the inner foam layer 1, so it is lightweight, has good cushioning properties, and has the effect of reducing lateral vibration. In addition, since the heel part has a structure in which the thick heel part of the inner foam layer 1 is enclosed and is covered by the thin layer of the outer foam layer 2, it is lightweight without causing sink marks. It is highly flexible and has the effect of cushioning and absorbing the impact upon landing. Furthermore, since the inner foam layer 1 is covered with the outer foam layer 2, which has a higher hardness than the inner foam layer 1, the hardness on the upper surface decreases from the contour to the center, and the hardness changes smoothly, making it easier to wear. This significantly improves the comfort of wearing the shoes without causing discomfort such as unevenness on the feet of the wearer.

In addition to the above-mentioned effects, the most characteristic effect of the present invention is that at the stepping part of the midsole where the bending and stretching action is most intense and at its both outer edges, the outer layer foam 2 made of polyester-based foamed polyurethane is By replacing the inner layer foam 1 with an appropriate number of protrusions 3 made of foamed EVA having low hardness, when the stepping part is bent and stretched, the protrusions 3 of the foamed EVA can be easily compressed and expanded. It can alleviate and absorb bending/stretching forces, reduce bending/stretching resistance on the wearer's feet, and dramatically eliminate fatigue. In addition, the landing begins almost at the center of the heel, and the stepping movement moves along the outside from the ball of the little toe to the ball of the big toe, and after landing, the ground is mainly touched by the ball of the big toe and the second and third toes. Therefore, by replacing the outer edge of the heel portion of the outer foam layer 2 with the protrusion 3 of the inner layer foam 1, which has a lower hardness than the outer layer foam 2, as described above, the center of the heel is first As soon as landing starts, the protrusion 3 on the outside of the heel is compressed by the pressure of the foot, so it acts as a guide to move the foot from the center of the heel to the outside of the heel. By making the contour width of the inner edge of the outer layer foam 2 from the inner side of the heel to the arch wider than the contour width of other parts, the movement of the foot can be reliably moved along the outer side of the heel with more cushioning properties. Since the foot can be moved toward the tip, it is possible to avoid damage to the ankle, etc., which occurs when the foot is moved forward along the inside of the heel. Furthermore, if the outer layer foam 2 is cut out in the stepping-corresponding part and the heel-corresponding part, so that the entire upper surface of the inner layer foam 1 is exposed.
The above-mentioned effects are further promoted, and since the protrusions 3 of the inner layer foam 1 are exposed on both side end faces of the stepping part and the outer end face of the heel, the protrusions 3 can be formed in a desired color and shape. If formed, it can become a strong accent, improve aesthetics, and give a good impression.

The midsole of the present invention is comprised of at least two polymeric foam layers mounted between the outsole and the cover, the polymeric foam layers having a contour that roughly follows the outsole, and an elastic inner layer. Since the foam is covered with an outer layer foam made of polyester urethane which has a higher hardness than the inner foam layer, the inner layer foam 1 has the advantages of excellent cushioning properties and light weight, and the outer layer foam 2 has a synergistic effect due to its excellent fracture strength, low compression set, and good recovery power.
By changing the outer contour width of the bending part and the heel part or the thickness of each partial layer of the inner layer foam 1, it is possible to adjust the structure to a predetermined value. It is possible to improve running functions such as anti-rolling and achieve these optimal effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a plan view of another embodiment, and FIG. 4 is a longitudinal sectional view thereof. 1... Inner layer foam, 2... Outer layer foam, 3...
Projection, 4...Curved portion.

Claims (1)

[Scope of Claims] 1. Consists of at least two layers of elastic inner layer foam 1 and outer layer foam 2 of polyester-based urethane, which are attached between the outsole and the shoe cover, and these polymer foams 1 . A midsole characterized by being filled with protrusions 3 of an inner layer foam 1. 2. The inner layer foam 1 is provided with a curved portion 4 that is concave toward the center from the inside of the heel to the arch, and the contour width of the outer layer foam 2 is made larger than other contour widths in proportion to this curved portion 4. The midsole according to claim 1, characterized in that the inner layer foam 1 and the outer layer foam 2 are combined. 3 The hardness of the inner layer foam 1 is 20 to 60 degrees on the Asker hardness tester C type, the hardness of the outer layer foam 2 is 25 to 80 degrees on the same type, and the hardness of the outer layer foam 2 is higher than the hardness of the inner layer foam 1. A midsole according to claims 1 and 2, comprising polymeric foam layers combined in such a manner that the midsole has a high polymeric foam layer. 4. The midsole according to claim 2, characterized in that the outer layer foam 2 is cut out in the stepping-corresponding part and the heel-corresponding part, so that the entire upper surface of the inner layer foam 1 is exposed.