Thermoplastic copolycarbonate from halogen free aromatic diol and halogenated thiodiphenol

摘要

Polycarbonates are provided having improved critical thickness values and flame retardant characteristics based upon an aromatic diol and a halogenated thiodiphenol represented by the structural formula <IMAGE> wherein X1 and X2 are halogen and "a"+"b"=1 to 8; Y1 and Y2 are alkyl groups having 1 to 4 carbon atoms; and "c"+"d"=0 to 7. By incorporating an effective amount of the aromatic halogenated thiodiphenol, based upon the total aromatic diol content, into the polymer the critical thickness and flame retardant characteristics of the polycarbonate are substantially improved, a process for the preparation of the monomer of said structural formula is likewise provided.