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:
Feb. 10, 1998
Filed:
Dec. 17, 1996
Godavarthi Satyanarayana Varadarajan, Niskayuna, NY (US);
Swaminathan Sivaram, Pune, IN;
Bhaskar Bhairavnath Idage, Pune, IN;
Joseph Anthony King, Jr, Schenectady, NY (US);
General Electric Company, Schenectady, NY (US);
Abstract
Solid state polycarbonate formation comprises an initial step of converting a precursor polycarbonate to an enhanced crystallinity precursor polycarbonate and a second step of polymerizing said enhanced crystallinity precursor polycarbonate in the solid state. Several options are employed. These include modifying the precursor polycarbonate by contact with a dihydroxy compound or diaryl carbonate, conversion of the precursor polycarbonate to the enhanced crystallinity polymer by contact with at least one compound selected from the group consisting of alkali metal hydroxides, tetraalkylammonium hydroxides, tetraalkylammonium carboxylates, tetraalkylphosphonium hydroxides and tetraalkylphosphonium carboxylates, and conducting the solid state polymerization in the presence of a catalytic amount of at least one tetralkylammonium or tetraalkylphosphonium carboxylate. The preferred tetralkylammonium compounds are tetramethylammonium maleate and tetramethylammonium hydroxide. Polymerization may be conducted in the presence of a solvent resistance-imparting monomer such as hydroquinone or resorcinol or a branching agent such as 1,1,1-tris(4-hydroxyphenyl)ethane.