Hydrolytisch stabile Polycarbonate sowie Verfahren zu deren Herstellung

摘要

Polycarbonates are made by (a) making a low molecular weight polycarbonate by reacting in in inert organic solvent containing an acid acceptor a molar excess of a carbonyl halide with a tetra-alkyl alkylidene bisphenol of formula where R is an alkylidene radical containing 1-10 carbon atoms or a cycloalkylidene radical containing 5-8 carbon atoms in the cyclic ring and R1, R2, R3 and R4 are C1- 3/t alkyl radicals and (b) reacting this low molecular weight polycarbonate with a certain dihydric phenol in the presence of a carbonyl halide; the molar amount of this dihydric phenol being less than that of the tetra-alkyl alkylidene bisphenol. The dihydric phenols to step (b) have the formulae where R is an alkylidene radical containing 1 to 10 carbon atoms or a cycloalkylidene radical containing 5-8 carbon atoms in the cyclic ring; R5, R6 and R7 are halogen atoms or C1- 3 alkyl radicals; each of p and q is 0, 1 or 2 except that where R5 and R6 are both alkyl, each of p and q is 0 or 1; and each of m, n and s is 0, 1 or 2. The presence of carbonyl halide for step (b) may be assured by adding additional carbonyl halide or by using up unreacted carbonyl halide from step (a). The acid acceptor is preferably a tertiary amine.