STOPPERS OF COMPOSITE CORK MATERIAL FOR SPARKLING WINES AND THE PROCESS FOR THEIR PRODUCTION [US8414809B2, US20090236306A, EP2099689B1, JP5576119B2, CN101563274B, ES2334767T3, RU2461504C2]; JOÃO CARLOS MOURA BORDADO, JAIME NOTÓ, ANTÓNIO MANUEL DE MAGALHÃES MOREIRA BASTOS- 2011-2013
Abstract: Stoppers made from composite material for sparkling wines consisting of two types of cork agglomerate which are closely bonded and produced from two ranges of granulates of different granulometry, where the joining surface between the two agglomerates is irregular due to their interpenetration. A production process of such stoppers by individual molding (piece by piece), where there is simultaneous feeding of two types of granulate and respective additives into a mold. The mold is then closed and the material compressed and heated for an appropriate time for polymerization. The granulates used are normally treated with a reactive agglomerant consisting of, for example, quasi-prepolymer based on TDI or quasi-prepolymer based on MDI base. After de-molding, the unfinished stopper is stabilized, and later machined to the final dimensions.