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:
Mar. 21, 1989
Filed:
Dec. 17, 1987
Glenn W Crowther, Newark, DE (US);
Christopher T Hyde, Lincoln University, PA (US);
Robert L Henn, Wilmington, DE (US);
W. L. Gore & Associates, Inc., Newark, DE (US);
Abstract
The present invention provides a two component polyurethane system with excellent wetting properties for casting a supported or unsupported, expanded polytetrafluoroethylene structure. It consists essentially of a polyisocyanate component having an isocyanate functionality of 2.2 or less and a polyol blend having an overall hydroxyl functionality of 2.2 or less and a viscosity of less than 500 cps., preferably 200 cps. or less. The polyol blend consists essentially of (i) a linear polyether or polyester (about 200-2500 molecular weight), (ii) a diol or triol (less than 200 molecular weight), and (iii) a catalyst in an amount sufficient to provide gelling at greater than 2 minutes and less than 10 minutes. The isocyanate to hydroxyl ratio is between 0.95:1 and 1.10:1. In some cases, it is desirable to include selected siloxane surfactants when polyol blends with the higher viscosities, i.e., about 200-500 cps., are used. The casting system is useful for making membrane filters.