Dual-density EVA footwear mid-sole and method for making same

Abstract

The method for fabricating a dual-density mid-sole includes the steps of: injection molding EVA material of a first density into a block; placing the first density EVA block and raw EVA material pellets of a second density together in a mold cavity; and applying heat and pressure to the first density EVA block and raw EVA material pellets of a second density in the mold cavity to form a fused component. The fused component is shaped and detailed into the mid-sole in a separate mold cavity. The result is a dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density where the size, shape and location of the different density sections can be accurately controlled and precisely defined. An article of footwear including an upper, the dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density, and an outsole, may be formed.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to footwear and to a method for making footwear and more particularly to a dual-density EVA footwear mid-sole and a method for making same.[0003]2. Description of Prior Art Including Information Disclosed under 37 Cfr 1.97 and 1.98[0004]Footwear mid-soles fabricated from ethylene-vinyl acetate (EVA) material are known in the art. Methods of fabricating EVA mid-soles are also known. Such methods normally include heating and applying pressure to raw EVA material in a mold cavity to fuse the material into the desired shape. After the component is removed from the mold and cured, it is shaped further and the exterior is detailed. The mid-sole is then incorporated into the footwear product using conventional fabrication techniques.[0005]Fabrication of the EVA mid-sole in this fashion results in a mid-sole with a substantially uniform hardness throughout. However, for certain applications, it has...

AI Technical Summary

Benefits of technology

[0046]FIG. 12 is perspective view of the mold cavity and contents as heat and pressure

Problems solved by technology

While this single step molding process results in a mid-sole with sections of different hardness due to the different densities of the raw EVA materials, the boundaries of the different density sections are not well defined and are difficult to control.

Further, the different density sections are not uniform in size and shape from one mid-sole to another.

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