Branched polycarbonates
View Patent ↗A branched polycarbonate and processes for its preparation are disclosed. The polycarbonate contains structural units conforming to in which R 1 , R 2 , R 3 and R 4 mutually independently denote C 1 -C 10 alkyl, R 5 , R 6 and R 7 mutually independently denote hydrogen or C 1 -C 10 alkyl, or R 1 and R 2 , and R 3 and R 4 , with the carbon atom to which they are attached, form a C 5 -C 10 cycloalkyl group, wherein the cycloalkyl group may be substituted.
1. In the process of producing branched polycarbonate by the phase boundary process the improvement comprising using at least one compound conforming to formula (1)
in which
R 1 , R 2 , R 3 and R 4 mutually independently denote C 1 -C 10 alkyl,
R 5 , R 6 and R 7 mutually independently denote hydrogen or C 1 -C 10 alkyl, or
R 1 and R 2 , and R 3 and R 4 , with the carbon atom to which they are attached, form a C 5 -C 10 cycloalkyl group, wherein the cycloalkyl group may be substituted said compound characterized in that it is the crude, unpurified product of re-crystallization or melt crystallization of bisphenol A or its derivative.
2. In the process of producing branched polycarbonate by the melt transesterification process the improvement comprising using at least one compound conforming to formula (1)
in which
R 1 , R 2 , R 3 and R 4 mutually independently denote C 1 -C 10 alkyl,
R 5 , R 6 and R 7 mutually independently denote hydrogen or C 1 -C 10 alkyl, or
R 1 and R 2 , and R 3 and R 4 , with the carbon atom to which they are attached, form a C 5 -C 10 cycloalkyl group, wherein the cycloalkyl group may be substituted said compound characterized in that it is the crude, unpurified product of re-crystallization or melt crystallization of bisphenol A or its derivative.
3. The process of claim 1 wherein said compound is the distillation product of a bisphenol A stream from its production.
4. The process of claim 2 wherein said compound is the distillation product of a bisphenol A stream from its production.