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:
Jul. 24, 1990
Filed:
Dec. 15, 1988
W Dirk Klobucar, Baton Rouge, LA (US);
Allan A Eisenbraun, Baton Rouge, LA (US);
Ronald C Zumstein, Baton Rouge, LA (US);
Ethyl Corporation, Richmond, VA (US);
Abstract
Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)-phenyl]hexafluoropropanes. The process involves forming, heating and agitating in a medium composed of dipolar aprotic solvent and liquid aromatic hydrocarbon solvent, a homogeneous solution of a polyamic acid derived from a substantially equimolar mixture of (i) an aromatic tetracarboxylic dianhydride and (ii) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane, such that a separate phase of particulate aromatic polyimide is formed in such medium. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.