| US 7,521,505 B2 | ||
| Method of stabilization of dihydric phenols | ||
| Venugopal Boddapaty Venkata, Bangalore (India); Gurram Kishan, Bangalore (India); Jan Pleun Lens, Breda (Netherlands); Daniel Francis Lowery, Schenectady, N.Y. (US); Mahesh Malusare, Bangalore (India); Patrick Joseph McCloskey, Watervliet, N.Y. (US); and Manisha Potdar, Bangalore (India) | ||
| Assigned to SABIC Innovative Plastics IP B.V., Bergen op Zoom (Netherlands) | ||
| Filed on Jun. 12, 2006, as Appl. No. 11/423,531. | ||
| Prior Publication US 2007/0287797 A1, Dec. 13, 2007 | ||
| Int. Cl. C08G 64/20 (2006.01); C08K 5/092 (2006.01); C08L 69/00 (2006.01) | ||
| U.S. Cl. 524—773 [524/321; 528/198] | 16 Claims |
| 1. A method of producing a polycarbonate, the method comprising:
polymerizing a dihydric phenol and a carbonate precursor in the presence of oxalic acid to provide a polycarbonate with a
yellowness index of less than or equal to 10 measured in accordance with ASTM E313 test method on molded samples having a
thickness of about 2.5 millimeters;
wherein the amount of oxalic acid ranges from about 20 parts per million to about 350 parts per million, relative to an amount
of the dihydric phenol; wherein the dihydric phenol is represented by Formula (I):
 wherein R is a hydrogen atom or an aliphatic functionality having 1 to 6 carbon atoms; and n is an integer having a value
of 1 to 4.
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