R¹-R⁶ are each independently a hydrogen atom; a hydroxyl group; or an organic group selected from alkyl groups, alkoxy groups, dialkyl amino groups, alkyl carbonyloxy groups, aryl group, arylated alkyl groups, aryloxy groups, arylated alkyloxy groups, and aryl carbonyloxy groups having 18 or less carbon atoms, wherein the alkyl part of said organic groups is optionally substituted by a hydroxyl group, halogen atom, cyano group or nitro group, interrupted by an oxygen atom, sulfur atom, carbonyl group, ester group, amide group or imino group, or have a double bond, or a combination of these substitutions, interruptions and double bonds, and

wherein said polymer is a polyolefin, a polyolefin copolymer, a polyvinyl chloride, a polyvinylidene chloride, a chlorinated polyethylene, a polyvinylidene fluoride, a chlorinated rubber, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-ethylene copolymer, a vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, a vinyl chloride-acrylic ester copolymer, a vinyl chloride-maleate copolymer, a vinyl chloride-cyclohexyl maleimide copolymer, a polycarbonate, a branched polycarbonate, a polyamide, a denatured polyphenylene oxide, a polyphenylene sulfide, a polyacetal, a denatured polyacetal, a polysulfone, a polyether sulfone, a polyether ketone, a polyether imide, a polyoxyethylene, a petroleum, a cumarone, a cycloolefin, a polyvinyl acetate, a polyvinyl alcohol, an acrylate, a polymer alloy of polycarbonate and a styrene resin, a polyvinyl alcohol, a cellulose resin, a liquid crystal polymer, a silicone resin, a urethane, a biodegradable resin, a phenol resin, a urea resin, a melamine resin, an epoxy resin, an unsaturated polyester resin, natural rubber, polvisoprene rubber, a styrene-butadiene rubber, a polybutadiene rubber, an ethylene-propylene-diene rubber, an isobutylene-isoprene rubber, a polychloroprene rubber, a acrylonitrile-butadiene rubber, or a silicone rubber.