Stabilizers for polymers containing aliphatically-bound bromine

Abstract

Aliphatic bromine-containing polymers are stabilized using a mixture of an alkyl phosphite and an epoxy compound. This stabilizer package is very effective at preventing cross-linking reactions from occurring when the aliphatic bromine-containing polymer is subjected to high temperatures as are seen in melt processing operations. The stabilized aliphatic bromine-containing polymer is useful as a flame retardant for other polymers, notably polystyrene foam.

1 - 15 . (canceled) 
     
     
         16 . A method for reducing gel formation in a brominated styrene-butadiene copolymer during melt processing, comprising performing the melt processing of the brominated styrene-butadiene copolymer in the presence of a mixture of at least one alkyl phosphite and at least one epoxy resin compound, wherein from 1 to 40 parts by weight of the alkyl phosphite are present per 100 parts by weight of the brominated styrene/butadiene block copolymer and further wherein from 1 to 40 parts by weight of the epoxy resin are present per 100 parts by weight of the brominated styrene/butadiene block copolymer. 
     
     
         17 . The method of  claim 16  wherein the melt process is performed in the presence of an organotin compound selected from the group consisting of alkyl tin thioglycolates, alkyl tin mercaptopropionates, alkyl tin mercaptides, alkyl tin maleates and alkyl tin (alkylmaleates), wherein the alkyls are selected from methyl, butyl and octyl.