Flame resistant sulfur-bearing copolycarbonate

Claim 1

An aromatic high molecular weight copolycarbonate comprising the polymeric reaction product of solely (i) an aromatic sulfur-free diphenol represented by the structural formula ##STR5## wherein b is zero or 1, Y denotes an alkylene or alkylidene radical with 1 to 7 carbon atoms, a cycloalkylene or cycloalkylidene radical with 5 to 12 carbon atoms, --O-- or --CO--; (ii) a sulfur-containing diphenol represented by the formula ##STR6## wherein R 1 and R 2 independently denote a lower alkyl selected from a group consisting of methyl, ethyl, propyl and butyl; n is equal to from 0 to 2 and T is either S, SO or SO 2 ; (iii) a branching agent for polycarbonates; (iv) a monophenol; and (v) a carbonic acid derivative selected from a group consisting of phosgene, carbonyl bromide or bis-chloroformic esters of an aromatic dihydroxy compound; characterized in that said branching agent comprises between 0.05 and 2%, relative to the molar sum of said (i) plus said (ii) and in that said copolycarbonate comprises at least 15 mol percent of said (ii) and in that they are classified V-O for 1/16" class specimens as evaluated by the procedure of Underwriter's Laboratories Bulletin 94.