A branched polycarbonate resin especially useful for blow molding, sheet extrusion, and injection molding has greatly decreased gel content, excellent transparency, mechanical strength, and room temperature impact resistance

摘要

A branched polycarbonate resin having excellent impact resistance at room temperature can be obtained by optimization of the point in time of addition of monomer, branching agent, tetraammonium salt, molecular weight modifier, and polymerization catalyst, where the content of gel component of particle size more than 50 micron insoluble in a good solvent is greatly decreased. A branched polycarbonate resin of viscosity average molecular weight (Mv) of 15000 to 45000, in which the number of gel-like particles insoluble in dichloromethane of particle diameter more than 50 micron is 10 or less per 100 g of resin is obtained by reaction of a bisphenol with a trihydric or multihydric phenol as molecular weight modifier, and phosgene in the presence of aqueous alkali solution and an organic solvent to form a polymer. An Independent claim is included for preparation of a branched polycarbonate by reaction of a bisphenol with a monohydric or multihydric phenol in the presence of phosgene, aqueous alkali solution, and an organic solvent as above, addition of a tetraammonium salt to the reaction mixture to start the polycondensation reaction, addition of a monohydric phenol as molecular weight modifier and a tertiary amine polymerization catalyst, so that the viscosity average molecular weight Mv in the reaction mixture containing the product is more than 3000 and less than 6000, further polycondensation, to give a branched polycarbonate resin of viscosity average molecular weight Mv of 15000 to 45000, and the number of particles insoluble in dichloromethane of particle size less than 50 micron 10 or less per 100 g of resin.