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. 12, 2000
Filed:
Jul. 30, 1998
David R Holm, Hudson, WI (US);
Daniel T Chen, St. Paul, MN (US);
Robert S Davidson, Edina, MN (US);
Eugene E Harkins, Vadnais Heights, MN (US);
3M Innovative Properties Company, St. Paul, MN (US);
Abstract
A continuous, preferably counter-current, extraction process that can be used to significantly reduce the concentrations of residual monomers, residual catalyst, undesired solvents, and other impurities in polymer compositions. The invention is particularly beneficial for extracting residual monomers and other impurities from viscous, sticky polymer solutions, such as solutions of PSAs and low cohesive strength polymer compositions that phase change during extraction (i.e., change from liquid to solid, or precipitate), in a continuous manner. The polymer composition can be extruded into an extraction solvent as fibers in a vertical extraction column, under conditions such that at least a portion of an impurity is extracted from the polymer into the extraction solvent.