Method for increasing viscosity uniformity in polycarbonate manufacture
AssigneeGeneral Electric Company
InventorsRandy Northrop, Kent Wenderoth
Life of this patent
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Abstract
Polycarbonate batches dissolved in dichloromethane and having a solids content ranging from about 10 to about 30 weight percent are solution blended in a vessel. The batch-to-batch viscosity (MW) variability is reduced by about 40 to about 260 percent. The invention is effective with polycarbonate materials in the molecular weight range of about 15,000 to about 100,000 amu, regardless of chain terminator, co-monomer or branching agents used.
Claims14
A process for treating polycarbonate to reduce batch-to-batch variations in viscosity, said process comprising:
- mixing solutions of successive batches of polycarbonate dissolved in an organic solvent to form a solution containing from about 10 to about 30 weight percent solids;
- blending said solution for a time period sufficient to reduce batch-to-batch variations in viscosity of said polycarbonate before recovery of said polycarbonate from said solution;
- and
- recovering said polycarbonate from said solution after said blending step.
A method for decreasing batch-to-batch viscosity variability in polycarbonates comprising the steps of:
- blending batches of polycarbonates in the molecular weight range of from about 15,000 to about 100,000 atomic mass units as determined by gel permeation chromatography dissolved in an organic solvent from about 10 to about 30 weight percent solids resulting in a decrease in batch-to-batch variability of at least about 40 percent.
Dependencies are inferred from the claim text.