The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 11, 2001
Filed:
Feb. 16, 1999
Hoang T. Pham, Lake Jackson, TX (US);
Richard O. Kirk, Lake Jackson, TX (US);
Paul D. Haemhouts, Antwerp, BE;
The Dow Chemical Company, Midland, MI (US);
Abstract
A process for reducing polymer surging, lowering pressure and temperature fluctuations, and reducing polymer degradation while providing good overall throughput rate when plasticating and extruding low bulk density polycarbonate materials. The process involves a two-stage extrusion screw having a feed section with a constant channel depth of at least about 12 percent of the screw diameter and a transition section having a compression ratio of at least about 3:1. Thermoplastic low bulk density polycarbonate materials are extruded through a die in the shape of sheets, profiles, or films.