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:
Aug. 09, 1994
Filed:
Nov. 15, 1993
Viesturs Lesins, Buffalo, NY (US);
Occidental Chemical Corporation, Niagara Falls, NY (US);
Abstract
Disclosed is a method of making oxydiphthalic anhydride from oxydiphthalic acid. The oxydiphthalic acid is mixed with an organic liquid that codistills with water and the resulting slurry is heated to the boiling point of the slurry to remove any water. About 1 to about 4 moles of acetic anhydride per mole of oxydiphthalic acid are added to the slurry and the slurry is heated to a temperature between 50.degree. and 160.degree. C. until the oxydiphthalic acid content thereof is less than 0.1 weight percent. The slurry is filtered and the filter cake is heated to a temperature between about 180.degree. C. and below its melting point for about 12 to about 24 hours.