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:
Nov. 20, 1990
Filed:
Oct. 13, 1989
Donald F Hagen, North Oaks, MN (US);
Steven J St Mary, North Oaks, MN (US);
Louis A Errede, North Oaks, MN (US);
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
A composite chromatographic sheet-like article is prepared by the steps comprising blending one or more non-swellable sorptive hydrophobic particulate materials in the presence of an amount of polar organic masking agent sufficient to allow rapid wetting of the surface of the particulate and in the presence of sufficient lubricant water to exceed the sorptive capacity of the particulate, provided that the volume ratio of water to masking agent does not exceed 3:1, adding with stirring an aqueous emulsion of polytetrafluoroethylene so that the resulting mass has a dough-like consistency, mixing the mass in an intensive mixer at a temperature between 50 C. and 100 C. for a time sufficient to cause fibrillation of the polytetrafluoroethylene particles, biaxially calendering the mass, while maintaining water at a level near the absorptive capacity of the particulate, between a gap in the calendering rolls maintained at about 50 C. to about 100 C. to cause additional fibrillation and consolidation of the polytetrafluoroethylene particles while closing the gap with each successive calendering operation, for a time sufficient to produce a composite chromatographic article having a net surface energy in the range of 20 to 300 milliNewtons per meter, and drying the resultant sheet.