US 5,473,046 A · Process for producing a branched polycarbonate

Abstract

A process for producing a branched polycarbonate which comprises using a branching agent containing 200 ppm or less of sulfur; a branched polycarbonate which is prepared by the interfacial method and contains 1.0 ppm or less of residual sulfur as an impurity; and a branched polycarbonate which is prepared by the melting method and contains 2.0 ppm or less of residual sulfur as an impurity; are provided. When the branched polycarbonate is produced by the interfacial method, the branched polycarbonate produced does not show deterioration in heat stability or cause mold corrosion. When the branched polycarbonate is produced by the melting method, the branched polycarbonate produced does not show deterioration in heat stability or in color tone.

Claims8

Dependent claims

A process for producing a branched polycarbonate, which comprises:

interfacially reacting a difunctional phenol and phosgene thereby preparing a polycarbonate oligomer;
reacting said polycarbonate oligomer in a preliminary condensation reaction with a polyfunctional branching agent containing 200 ppm or less of sulfur represented by the formula (I):
##STR8## wherein R.sup.1, R.sup.2, and R.sup.3 are independently hydrogen, an alkyl group having 1 to 5 carbon atoms or halogen, and m, n and p are each 0 or an integer of 1 to 4, under certain conditions such that the interfacial area of the emulsion is 40 m.sup.2 /liter or more;
and then bringing the product of the preliminary condensation into polycondensation with a difunctional phenol and a monofunctional phenol under certain conditions such that interfacial area of the emulsion is 40 m.sup.2 /liter or more.

1 more element

Dependencies are inferred from the claim text.

Process for producing a branched polycarbonate

Life of this patent

Process for producing a branched polycarbonate

Life of this patent

Abstract

Claims8