Shoe sole and method
An outsole ( 1 ) for a shoe has a backing member ( 4 ) of thermoplastic rubber and on an area of the exterior surface of that backing member an intermediate layer ( 12 ) of thermoplastic polyurethane and an outermost layer of fabric ( 10 ), the area comprising at least 51 percent of the contact surface of the outsole. In producing the outsole, a sheet of fabric is overlain with a sheet of thermoplastic urethane, the sheet is heated to about the melting point of the TPU to permit the TPU to adhere to the fabric, and the fabric is cooled. The TPU-covered fabric is cut to the size and shape required to fit a backing member, and position in a mold on a bottom surface of a mold, and a quantity of TPR is injected at a temperature lower than the melting point of the TPU but high enough to render the TPU tacky, to insure the inherence of the TPU-covered fabric to the backing, including the resultant outsole.
1. A method of producing an outsole comprising covering a sheet of fabric with TPU by superimposing said fabric and a sheet of TPU, heating said TPU sheet to about the melting point of the TPU to permit the TPU to adhere to the fabric, cooling the TPU covered fabric to harden the TPU; cutting said TPU covered fabric to the size and shape required to fit a backing member to which said covered fabric is to be attached; positioning said cut, covered fabric on a bottom surface of a mold, and injecting into said mold a quantity of TPR at a temperature lower than the melting point of said TPU but high enough to render the TPU tackily adherent, and cooling the resultant outsole.
2. The method of claim 1 wherein the TPR is subjected in the mold to about 30-35 kilograms pressure per square inch.
3. The method of claim 1 wherein the temperature of the TPR in the mold is about 75° C.-79° C. and the dwell time in the mold is about 2.5 to 3.0 seconds.
4. The method of claim 1 including the step, after the coating of TPU on the fabric has hardened, of scrubbing the outer surface of the TPU before the coated fabric is placed in the mold.
5. The method of claim 1 wherein said method provides an area of a ground contacting exterior surface of said backing member of a size that permits classification under the Harmonized Tariff Schedule at a tariff rate lower than a shoe having no fabric contact surface or a fabric ground contact surface that is smaller than that permitting such classification.
6. The method of claim 1 including the step of layering the ground-contacting side of the fabric with a TPU solution at about 150° C.
7. The method of claim 6 wherein the said side is layered in multiple passes to produce a coating about 0.2 mm thick.
8. The method of claim 7 wherein the layering of the fabric is done before the sheet of fabric is covered with a sheet of TPU.