JPH02224603A - Injection molding method of shoe sole - Google Patents

Abstract

PURPOSE:To obtain a shoe sole excellent in a shock absorbability and a durability by molding a shock absorbing layer 1 having many compressing holes opened on an upper surface and, thereafter, injection-foam-molding a mid sole by means of a foaming soft elastic body on the upper surface of the said impact absorbing layer. CONSTITUTION:By a soft transparent elastic body, a shock absorbing layer 1, whose bottom surface is exposed on the bottom surface of the shoe sole and which has many compressing holes 14 to be opened 142 on the upper surface, is molded, thereafter, a mid sole 2 is injection- foam-molded by means of the foaming soft elastic body on the upper surface, simultaneously, one part of the soft elastic body is made to fill the compressing holes 14 by means of an injection pressure, and it is foamed. In such a case, when the compressing holes 14 and 14 are formed in the same size on the whole, they are arranged concentratedly in an outer side peripheral part 11 of the water absorbing layer 1 of the shock, and when the compressing holes 14 and 14 are uniformly arranged on the whole, the compressing hole 14' arranged in the outer side peripheral part 11 is formed larger than the compressing hole 14' arranged in an inner side peripheral part 12, the outer side peripheral part 11 is positioned in the heel part outer side peripheral part of the shoe sole, the inner side peripheral part 12 is positioned in the inner side peripheral part of the heel part of the shoe sole, and they are embedded in the heel part of the shoe sole.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to an injection molding method for shoe soles.

(Prior Art) The applicant previously proposed, in Japanese Patent Application No. 59-135818, an athletic shoe in which a shock absorbing material in which a low-resilience foam was interposed and bonded between rigid plates was laminated on the heel of the shoe sole. did.

Shoe soles equipped with such shock absorbing materials exhibit relatively good shock absorption and landing stability during normal walking or light walking such as jogging, but they are used in tennis, basketball, soccer, and long distance walking. When the landing impact pressure is large, such as when running or jumping, a load of more than three times the body weight pressure is concentrated on the area corresponding to the lower protrusion of the calcaneus at the initial stage of landing, so the landing impact pressure must be reduced. The area corresponding to the lower protrusion of the calcaneus could not be absorbed sufficiently, and this kind of low-resilience foam had a large compression set, which caused it to compress and deform with long-term use, resulting in a lack of durability. .

In addition, a separately prepared shock absorbing layer must be laminated to the heel of the sole using an adhesive, resulting in complicated manufacturing and high costs.

(Problems to be Solved by the Invention) This invention provides a simple and inexpensive shoe sole that has good shock absorption even when the landing impact pressure is large, and also allows the shock absorption layer to be seen through, making it highly durable. This is what we are trying to provide.

(Means for Solving the Problems) The present invention will be explained below with reference to drawings showing the state of implementation of the present invention.The present invention is made of a soft transparent elastic body, the bottom surface of which is exposed to the bottom surface of the sole, and the top surface of which has openings 142, 142... After molding the shock absorbing layer 1 having a large number of compression holes 14, 14...
With a foamable soft elastic material on the upper surface of the shock absorbing layer 1,
The present invention provides an injection molding method for shoe soles, which is characterized in that the midsole 2 is injection foam molded, and a portion of this foamable soft elastic material is filled into compression holes 14, 14, and foamed by injection pressure. This is a summary.

In this invention, the shock absorbing layer 1 includes vinyl chloride resin, vinyl chloride ethylene copolymer resin, vinyl chloride vinyl acetate copolymer resin, ethylene vinyl acetate copolymer resin, 1.
It is molded from 2-polybutadiene resin, polyurethane, transparent rubber compound, etc. And its hardness is J
It is preferable that the hardness is 30° to 60″ according to IS K6301 Spring Type Hardness Test Type A.

If the hardness used is less than that, the shock absorption property due to compressive deformability will be improved, but the recovery power will be poor, permanent deformation will increase, and durability will decrease. Moreover, if the hardness is higher than that, the compressive deformability tends to decrease and at the same time, the shock absorbability tends to decrease. The shock absorbing layer 1 is provided with a large number of compression holes 14, 14, . . . whose horizontal cross section is circular, oval, or polygonal in the vertical direction.

In this invention, the compression holes 14.14 are arranged so that the surface area occupancy is larger on the outer side 11 of the shock absorbing layer than on the inner side 12.
4... are formed to have the same size as a whole, the compression holes 1 are arranged concentrated on the outer side 11, and the compression holes 1
4.14... When arranged uniformly throughout, the compression holes 14' arranged on the outer side 11 are arranged on the inner side 12.
It is formed larger than the compression hole 14″ arranged in the
If the outside side 11 is located at the outside side of the heel of the shoe sole, and the inside side 12 is located at the inside side of the heel of the shoe sole, and embedded in the heel of the shoe sole, 1 normal The maximum impact pressure at the initial stage of landing, which is applied to the outer side of the heel of the shoe sole during walking and running, is determined by the compression holes 14, 14, formed in the outer side of the shock absorbing material 14...
- layer is effectively absorbed and the compression formed on the medial edge 12 of the shock absorbing layer 1 when the medial edge of the heel of the sole lands on the ground following the landing of the outer edge of the heel of the shoe sole. Since the hole 14'' has a smaller surface area occupation rate than the compression hole 14' formed on the outer side 11, on the inner side 12,
The compressive deformation rate is suppressed more than that of the outer side portion 11, and the inner side of the heel portion of the sole is not excessively adducted, which is advantageous since overpronation is prevented. .

In this invention, the compression holes 14, 14...
If 41.141... is narrowed and its cross-sectional shape in the vertical direction is formed into a conical shape, the landing impact that could not be absorbed by the compression holes 14.14... will be absorbed from the radial direction of the lower surface, and the landing impact that could not be absorbed by the compression holes 14.14... Since it is dispersed along the wall surface 140 and in the radial direction of the upper surface, the impact mitigation properties are good, and the elastic recovery power is also good, making it possible to make the wearer's comfort even better.

Can be done.

In this invention, Midsol 2 includes vinyl chloride, vinyl chloride ethylene copolymer resin, vinyl chloride vinyl acetate copolymer resin, ethylene vinyl acetate copolymer resin, 1.2
It is injection molded using polybutadiene, natural rubber, synthetic rubber, etc. with a foaming agent added thereto, foamable polyurethane, and other materials normally used for molding foamed shoe soles. The hardness (SRIS 0101...Hardness according to the Japan Rubber Association's standard physical test method for expanded rubber) is 30@~60''
It is desirable to set it to . If the hardness is less than that, the mechanical strength such as compressive strength and tensile strength of the midsole 2 tends to decrease. The foamed filling portions 21, 21... filled in the holes 14, 14... prevent compression deformation of the compression holes], 4, 14... when the sole is used, and the shock absorption and cushioning properties of the sole tend to decrease. There is.

In addition, in this invention, if the midsole 2 is colored with a fluorescent pigment, fluorescent dye, or ordinary coloring pigment, the compression hole 14.
It is possible to more clearly see through the filling part where the midsole 2 is integrally filled and molded.

In the present invention, the shock absorbing layer 1 may be formed separately, set in a shoe sole mold, and the midsole 2 may be injection foam molded on the upper or lower surface of the mold. A grounding sole 3 provided with a notch 31 is molded, and a shock absorbing layer 1 is injected using a bottom mold 51 held by a notch holding protrusion 511 and a first upper mold 52' having compression hole forming protrusions 521, 521... on the lower surface. After molding, while the shock absorbing layer 1 is held in the bottom mold 51, the first upper mold 52' and the second upper mold 52 for molding the midsole are removed.
”, and the midsole 2 is placed on the top surface of the shock absorbing layer 1.
It is convenient to employ a method in which the shock absorbing layer 1 can be exposed in the notch 31 of the ground sole by injection molding.

Incidentally, 6 in the drawings indicates a flange suspended from the upper mold.

(Operations and Effects of the Invention) The present invention is constructed as described above, and compressed holes 1 are formed in the shock absorbing layer 1 by injection pressure of a part of the foamable soft elastic body for midsole molding during midsole injection molding.
4.14... is filled and foamed and the shock absorbing layer 1 and the midsole are laminated, so molding is easy, and the sole molded in this way is inexpensive. In addition, when walking or running, the landing impact pressure applied to the sole of the shoe is absorbed by the compression holes 14.14 formed in the shock absorption layer 1 and the midsole 2 formed by filling the compression holes 14.14 with foam. Since the shock is absorbed by compressive deformation of the filling part 21, the shock absorption property is good.
In addition, the impact-absorbing layer 1 has a smaller compression set than conventional low-resilience foams and has good durability without being permanently compressed even after long-term use.

Compression holes 14.14 are also formed in the transparent shock absorbing layer 1.
. . . and the filling portion 21 integral with the midsole filled in the compression holes 14, 14 . . . can be seen through the notch 3 of the ground sole at the bottom of the sole, and the impact absorption effect can be visually appealed.

[Brief explanation of the drawing]

The drawings show the implementation state of the present invention, and FIG. 1 is a cross-sectional view of the main part showing the molded state of the shock absorber in the first embodiment, and FIG. 2 is a cross-sectional view of the main part showing the molded state of the midsole. It is a diagram. 140... Wall surface 142... Opening 21... Filling part 31, notch part 51... Bottom mold 511... Protrusion 52 (52', 52'')... Upper mold 53... Side mold 6, lace part 141... Center part 2, midsole 3, contact Underground 521...protrusion

Claims (1)

[Claims] Due to the soft transparent elastic material, the bottom surface is exposed to the bottom surface of the sole,
A large number of compression holes 14, 1 with openings 142, 142... on the upper surface.
After molding the shock absorbing layer 1 having 4..., the midsole 2 is injection foam molded on the upper surface of the shock absorbing layer 1 using a foamable soft elastic material, and a part of this foamable soft elastic material is A shoe sole injection molding method characterized by filling compression holes 14, 14... with injection pressure and foaming.