JPH04135501A - Production of injection molded shoe - Google Patents

Abstract

PURPOSE:To eliminate the need for excess parts and excess stages and to reduce the costs of the shoes by combining a last with a lower mold having a cavity for forming an outer sole atop the mold and injecting and packing thermoplastic rubber or resin into the hermetically closed cavity part. CONSTITUTION:Uppers formed by using polyvinyl chloride leather for the insole cloth are deposited on the last and an open cellular foam of natural rubber latex (stuck with a cotton cloth on the surface in contact with a material to be injected and packed) is stuck on the rear surface of the heel part of the uppers by the pressure sensitive latex of natural rubber. The temp. of the last of this time is about 70 deg.C. Such last and the lower mold are combined and the solid compounded polyvinyl chloride is injected and filled under about 3 to 5kg/cm<2> micropressure into the cavity and the molding is parted from the mold after curing. The thickness of the foam expanded on the bottom surface of the heel part is about 2mm. The injection molded shoes which eliminate food contact and have a good wearing feel are produced by the min. number of parts and min. stages in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method for manufacturing an injection molded shoe having a foamed midsole heel.

<Prior Art> Injection-molded shoes with California-type uppers, such as shoes with outer soles made of thermoplastic rubber or resin by injection molding, have hard outer soles that touch the foot during wear, making them difficult to wear. There were some drawbacks that made it uncomfortable. For this reason, conventionally, in the case of early-style shoes that are worn formally, a foam sheet of a predetermined shape is attached to the heel part of the upper surface of the midsole, for example, in order to eliminate foot contact and improve comfort. In the first half, a semi-insole made of synthetic leather or the like was attached to cover the foam sheet to prevent it from rolling up while being worn.

<Problems to be Solved by the Invention> However, the above-mentioned injection molded shoes have the drawback that they require extra parts and extra steps due to the use of a semi-midsole, making the shoes expensive.

The present invention seeks to provide a method for manufacturing injection molded shoes that does not have such drawbacks.

<Means for Solving the Problems> The present invention provides a shoe last covered with a California type upper in which a foam sheet of a predetermined shape is attached to the lower surface of the heel, and a hollow portion for forming an outer sole is placed on the upper surface. The gist of the present invention is a method for manufacturing injection-molded shoes, characterized in that thermoplastic rubber or resin is injected and filled into the sealed cavity in combination with a lower mold having a lower mold.

The foam sheet is most often used in the form of an oblong with a major axis of 60 mm, a minor axis of 30 mm, and a thickness of 2 to 4 mm because it is attached to the heel.
Polyurethane foam expanded 0 to 20 times, 4 to 5
Rubber latex foam that has been expanded to double its original size is used.

Thermoplastic rubber or resin: Polyvinyl chloride.

Polyurethane, ethylene, vinyl acetate copolymer rubber, etc. are used.

In addition, the insole fabric of the California type instep is 70 to 8
If you use a material (such as polyvinyl chloride) that is easy to stretch at 0"C, the heel of the finished injection molded shoe will have
It is preferably used because the convex shape of the foam sheet stands out clearly.

<Function> When the greatly expanded foam sheet is attached to the shoe last and the cavity is injected and filled with thermoplastic rubber or resin, the foam sheet contacts the bottom surface of the shoe last and the filled thermoplastic rubber or resin. The resin is sandwiched and compressed.

Therefore, when the filled thermoplastic rubber or resin cures and the finished injection molded shoe is released from the mold, the compressed foam sheet is released from compression and is attached to the foot contact side of the insole fabric. The desired injection molded shoes will be obtained.

<Example 1> An upper whose insole fabric is made of polyvinyl chloride leather is attached to the shoe last, and a natural rubber latex open foam with a specific gravity of 0.30 (minor axis 30 mm, major axis 60 mm, thickness 4mm
(oblong shape), (cotton cloth is attached to the surface in contact with the material to be injected and filled) were laminated with natural rubber pressure-sensitive latex.

The shoe last temperature at this time was 70'C. This shoe last and lower mold were combined, and the cavity was filled with solid polyvinyl chloride by injection at a micro pressure of 3 to 5 kg/ci, cured, and released from the mold. At this time, the thickness of the expanded foam at the heel contact surface was 2 mm.

Note that when a foam with a thickness of 2 rrun was used, the expanded thickness was Imm.

<Example 2> When cotton cloth is used as the insole in the above example, if the foam has a thickness of 4 cm or 2 peng, the swelling will be 1.5 nm.
Or o, smm.

<Effects> By carrying out the manufacturing method of the present invention, comfortable injection molded shoes that do not touch the foot could be manufactured at low cost using a minimum number of parts and a minimum number of steps.

Claims (1)

[Claims] A last with a California-type upper with a foam sheet of a predetermined shape affixed to the lower surface of the heel is combined with a lower mold having a cavity for forming an outer sole on the upper surface, and a sealed former cavity is created. A method for manufacturing injection molded shoes, which comprises injection-filling thermoplastic rubber or resin into the shoes.