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:
Feb. 23, 1993
Filed:
Feb. 21, 1992
Robert F Zepf, San Diego, CA (US);
Memtec America Corporation, Timonium, MD (US);
Abstract
Ultraporous and microporous polymer membranes cast from metastable dispersions are significantly improved by limiting the time of environmental exposure to less than about 0.5, preferably less than 0.25 seconds, between casting and quenching, and reducing the casting temperatures about 10.degree. to about 20.degree. C. lower than the usual prior art values. The resulting membranes have far less debris entrained in the membrane, far more consistent and uniform pore sizes, a substantially greater number of skin pores, and greatly increased flow rates for any given pore diameter. The membranes are highly asymmetrical and skinned with a standard deviation in flow rate of less than about 400 and a flow rate covariance of less than about 6, with skin pore diameters of from about 0.001 .mu..