Method for controlling the manufacture of polycarbonate and the polycarbonate formed thereby
AssigneeGeneral Electric Company
InventorsGregory Lee Hemmer, Jon Bruce Mansfield
Life of this patent
Estimating the term…
Abstract
A method for determining the endpoint of an interfacial reaction between a dihydroxy compound and a carbonyl halide comprises determining the characteristic end point of the reaction from a characteristic pH trace over time or ratio between caustic and carbonyl halide trace over time for the reaction; obtaining a pH trace over time or a ratio between caustic and carbonyl halide trace over time during the reaction to be monitored; and identifying the end point of the monitored reaction when the obtained pH or ratio trace resembles the end point determined from the characteristic pH or ratio trace.
Claims16
A method for controlling the manufacture of polycarbonate, comprising:
- charging a reactor with carbonyl halide at a carbonyl halide flow rate corresponding to a carbonyl halide flow rate set point, wherein the reactor contains a dihydroxy compound, solvent, and optionally catalyst and endcapping agent;
- charging the reactor with caustic at a caustic flow rate, wherein the caustic flow rate is determined by a ratio between caustic and carbonyl halide set point;
- measuring pH of reactor process;
- comparing the measured pH to a pH set point having upper and lower constraints;
- calculating any difference between the measured pH and the pH set point;
- selecting the ratio within a first set of constraints based upon any difference to provide in a second ratio;
- manipulating one of a caustic flow rate or carbonyl halide flow rate to match the second ratio;
- selecting the second ratio within a second set of constraints based upon any pH difference to provide in a third ratio after a predetermined percentage of the total amount of carbonyl halide has been charged to the reactor;
- manipulating one of the caustic flow rate or the carbonyl halide flow rate to match the third ratio;
- producing a pH trace of the reaction over time;
- and
- producing a ratio trace of the reaction over time.
A method for monitoring an interfacial reaction between a dihydroxy compound and a carbonyl halide comprising:
- determining a characteristic pH trace over time and ratio between caustic and carbonyl halide trace over time for the reaction;
- obtaining a pH trace over time and ratio of caustic to carbonyl halide trace over time for the reaction to be monitored;
- diagnosing status and conditions of the reaction based on the pH trace and the halide trace;
- and
- executing maintenance of reactor process based, at least in part, on the diagnosis.
A method for identifying an end point of an interfacial reaction between a dihydroxy compound and a carbonyl halide, comprising:
- determining the characteristic end point of reaction from a characteristic pH trace over time or ratio between caustic and carbonyl halide trace over time for the reaction;
- obtaining a pH trace over time or ratio between caustic and carbonyl halide trace over time during the reaction to be monitored;
- and
- identifying the end point of the monitored reaction when an obtained pH or ratio trace resembles the end point determined from the characteristic pH or ratio trace.
Dependencies are inferred from the claim text.