Patent ID: 8506860

Claim:
A method of manufacturing foam, comprising the steps of: providing a lower mold having a molding surface, and then sequentially placing a middle mold having at least one protrusion formed on one side or both sides of the middle mold, and an upper mold having a molding surface on the lower mold, thus sealing the molds; simultaneously forming an upper preform and a lower preform by charging a foaming material in inner molding spaces of the upper and lower molds, which are compartmented by the middle mold, under a condition of preventing the foaming material from foaming; opening the molds and removing the middle mold from the upper and lower molds; placing an interface material in at least one groove formed in a surface of at least one of the preforms by the at least one protrusion of the middle mold such that the upper and lower preforms are prevented from cross-linking with each other; and sealing the molds and simultaneously cross-linking and foaming the upper and lower preforms.