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:
Apr. 25, 2000
Filed:
Mar. 11, 1998
Stephen Charles Webb, Emmaus, PA (US);
James Francis Nangeroni, Doylestown, PA (US);
Brian Thomas Carvill, Houston, TX (US);
Beth Ann Frey, Alburtis, PA (US);
Air Products and Chemicals, Inc., Allentown, PA (US);
Abstract
An improved process for the continuous production of poly(vinyl alcohol) which involves purifying poly(vinyl acetate) paste exiting from a polymerization reactor and dissolving the substantially pure poly(vinyl acetate) in a hydrolytic alcohol-containing solvent for subsequent saponification to produce poly(vinyl alcohol). Poly(vinyl acetate) paste, containing poly(vinyl acetate), vinyl acetate, and solvent, is heated to a temperature above the glass transition temperature but below a temperature which will degrade the poly(vinyl acetate) and is fed into a flashing area of an extruding devolatilization device. Vinyl acetate and solvent are flashed through vent ports in the flashing area of the devolatilization device and can then be recycled to a polymerization reactor, if desired. A substantially pure poly(vinyl acetate) melt, exiting the flashing area, is conveyed to a mixing area of the devolatilization device where it is mixed with a hydrolytic alcohol-containing solvent to form a solution for subsequent processing in a saponification unit.