Method and system for preparing a polycarbonate, copolymerization reagent and polycarbonate

A copolymerization reagent comprising a mixture of (B) a symmetrical optionally activated aromatic carbonic acid diester and (C) an optionally substituted aromatic hihydroxy compound, diol or diacid.

A method for preparing a copolycarbonate, comprising:

• reacting an (i) aromatic dihydroxy compound with a (ii) carbonic acid diester to prepare a (A) free hydroxyl-containing polycarbonate and reacting the (A) free hydroxyl-containing polycarbonate with a mixture of a (B) symmetrical optionally activated aromatic carbonic acid diester and an (C) optionally substituted aromatic dihydroxy compound, diol or diacid in a stoichiometric molar ratio of about 0.01 to about 0.75 (C) optionally substituted aromatic dihydroxy compound, diol or diacid to (i) aromatic dihydroxy compound reacted to form the (A) free hydroxyl-containing polycarbonate.

A method for preparing a copolycarbonate, comprising:

• reacting an (i) aromatic dihydroxy compound with a (ii) carbonic acid diester to prepare a (A) free hydroxyl-containing polycarbonate and reacting the (A) free hydroxyl-containing polycarbonate with a mixture of a (B) symmetrical optionally activated aromatic carbonic acid diester and an (C) optionally substituted aromatic dihydroxy compound, diol or diacid, wherein the activity of (A) the polycarbonate in reaction with the mixture of (B) and (C) is controlled by varying the free-hydroxyl content of (A).

A method for preparing a copolycarbonate, comprising:

• preparing a (A) free hydroxyl-containing polycarbonate and sequentially reacting the (A) free hydroxyl-containing polycarbonate in at least a first copolymerization and a second copolymerization with mixtures of a (B) symmetrical optionally activated aromatic carbonic acid diester and an (C) optionally substituted aromatic dihydroxy compound, diol or diacid.

A system for preparing a copolycarbonate, comprising:

• a first reactor for reacting an (i) aromatic dihydroxy compound with a (ii) carbonic acid diester to produce a polycarbonate;
• and
• a contiguous polymerizer for reacting a controlled stoichiometric mixture of a (B) symmetrical optionally activated aromatic carbonic acid diester and an (C) optionally substituted aromatic dihydroxy compound, diol or diacid with the polycarbonate to produce a copolycarbonate.