Patent ID: 8114476

Claim:
A process for improving the insulating capacity of expanded vinyl aromatic polymers which comprises: 1) preparing beads of expandable vinyl aromatic polymers containing 1-10% by weight, calculated with respect to the polymer, of an expanding agent incorporated in the polymeric matrix, and 0.01-25% by weight, calculated with respect to the polymer, of an athermanous additive comprising carbon black homogeneously distributed in the polymeric matrix with an average diameter ranging from 30 to 2000 nm, a surface area ranging from 5 to 40 m 2 /g, a sulfur content ranging from 0.1 to 1000 ppm, a content of ashes ranging from 0.001 to 1%; 2) treating the surface of the beads with a liquid lubricating agent selected from the group consisting of: i. a hydroxylated organic compound wherein the C/OH ratio, between the number of carbon atoms (C) and the hydroxyl groups (OH), ranges from 1 to 1.3; ii. a sodium phosphate of a C 10 -C 20 ethoxylated alcohol with 1-30 moles of ethylene oxide, iii. a benzyl or benzyl alkyl sulfate/sodium sulfonate, wherein the alkyl group has from 5 to 20 carbon atoms; iv. a chloride of ammonium alkyl-benzyl; v. an ester of fatty acids of coconut oil with choline chloride; and 3) thermally treating the beads with hot air at a temperature ranging from 30 to 60° C.