Patent ID: 8974711
Filing Date: 2015-03-10
Classification: A43B,B29D

Abstract:
1. A method for making an injection molded waterproof footwear product comprising a compressible lining material attached thereto whereby the compressible lining material becomes attached to the footwear product during injection molding of the footwear product, the method comprising: (a) providing a last having an exterior surface which corresponds to an interior surface of the footwear product; (b) covering at least a portion of the exterior surface of the last with a compressible microcellular lining material which compresses under pressure; (c) providing a first mold configured for injection of a flowable injection material into an injection cavity to form the footwear product wherein the first mold comprises first and second plates, and first and second shells, each said shell having a pre-determined configuration designed to account for a dynamic non-uniform compression of the compressible microcellular lining material during the injection molding, the pre-determined configuration of the shells designed to form: (i) prior to the injection molding, a pre-injection cavity between the shells and the compressible lining material covered last when the compressible lining material covered last is located in the mold between the first and second shells with the first and second plates on opposite sides of the shells, and with the plates in a closed position for injection molding; and, (ii) when the compressible lining material covered last is located in the mold with the plates in a closed position and the flowable injection material is being injected, a dynamically formed injection cavity between the shells and the compressible lining material covered last wherein the configuration of the injection cavity is dynamically formed by pressure applied during the injection of the flowable injection material which causes the compressible microcellular lining material to compress and thereby reconfigure the pre-injection cavity to form the injection cavity; (d) locating the compressible lining material covered last between the first and second shells with the first and second plates located on opposite sides of the shells, and closing the plates in position for injection molding, the pre-injection cavity formed between the shells and the compressible lining material covered last; (e) injecting under pressure the flowable injection material into the pre-injection cavity to form and fill the injection cavity with flowable injection material; (f) hardening the injected injection material whereby the hardened injection material attaches to the microcellular lining material, the hardened injection material and attached microcellular lining material together forming the footwear product; (g) opening the first mold to expose the footwear product; and, (h) removing the footwear product from the last, wherein the formed footwear product includes a molded foot portion adapted to extend completely around a wearer's foot and to cover a foot portion of the compressible microcellular lining material, and an upwardly-extending molded portion extending upward from the molded foot portion and covering a part of a leg portion of the compressible microcellular lining material while leaving another part of the leg portion of the compressible microcellular lining material uncovered.