| US 7,485,695 B2 | ||
| Polycarbonates containing low levels of methyl salicylate prepared by a melt polymerization in a reactive extruder | ||
| Peter Davis, Niskayuna, N.Y. (US); and Hans Looij, Bergen op Zoom (Netherlands) | ||
| Assigned to Sabic Innovative Plastics IP B.V, Bergen op Zoom (Netherlands) | ||
| Filed on Sep. 06, 2006, as Appl. No. 11/470,333. | ||
| Application 11/470333 is a continuation in part of application No. 11/275266, filed on Dec. 21, 2005. | ||
| Prior Publication US 2007/0142618 A1, Jun. 21, 2007 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. C08G 64/00 (2006.01); C08G 63/02 (2006.01) | ||
| U.S. Cl. 528—196 [264/176.1; 264/219; 422/129; 528/198; 528/310] | 36 Claims |
| 1. A method for preparing polycarbonate wherein the method comprises the steps of,
(i) introducing to an extruder through one or more feed sections, a plurality of reaction components comprising a dihydroxy
compound, an activated carbonate, and a transesterification catalyst, wherein the extruder comprises: (a) a first feed section;
(b) a polycarbonate exit section; and (c) a reaction section disposed between the first feed section and the polycarbonate
exit section,
the reaction section comprising one or more devolatilization units, wherein each devolatilization unit comprises an array
of vent-conveying sections and conveying sections arranged in a configuration selected from the group consisting of:
(CVC)x(V)n, and
(VCV)x(C)n
wherein (V) is a vent-conveying section, (C) is a conveying section, x is 1 or more, and n is 1 or 0,
wherein the extruder screw in the vent-conveying sections and the conveying sections in each devolatilization unit comprises
screw elements selected from the group consisting of mixing elements and conveying elements and no elements that create a
melt seal within the devolatilization unit, and
(ii) extruding the plurality of reaction components at a temperature in a range between 100° C. and 500° C., wherein during
the extrusion of the reaction components a volatile residue from the activated carbonate is removed from each devolatilization
unit, and polycarbonate is removed through the polycarbonate exit section.
|