Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2005-01-04
2005-01-04
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C422S131000, C528S198000
Reexamination Certificate
active
06838543
ABSTRACT:
Polycarbonates are produced by reacting a monomeric carbonate component with at least one diphenol or dialcohol in the presence of a transesterification catalyst, wherein the molten component is mixed with the transesterification catalyst by stirring and a transesterification product is produced, which is polycondensated. For polycondensation, the transesterification product is passed through a preliminary reactor, at least one intermediate reactor and one final reactor, the reactors being connected in series and having a substantially horizontal driven shaft with stirrers attached thereto. It is ensured that in the preliminary reactor and in the final reactor a dwell time of the melt of 5 minutes to 2 hours is maintained, that the temperatures in the preliminary reactor are maintained in the range from 220 to 300° C. and in the final reactor in the range from 240 to 350° C., and that the pressure in the preliminary reactor is maintained in the range from 100 to 800 mbar and in the final reactor in the range from 0.1 to 50 mbar.
REFERENCES:
patent: 6294352 (2001-09-01), Kimura
patent: 20010021765 (2001-09-01), Shimoda et al.
patent: 20030088051 (2003-05-01), Shimoda et al.
patent: 07 242743 (1995-09-01), None
Kaempf Rudolf
Wilhelm Fritz
Boykin Terressa
Zimmer AG
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