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:
Sep. 03, 1985
Filed:
Feb. 28, 1984
Gene H Shipman, Cottage Grove, MN (US);
Minnesota Mining and Manufacturing Co., St. Paul, MN (US);
Abstract
A method of making a microporous material is provided which comprises the steps of melt blending crystallizable thermoplastic polymer with a compound which is miscible with the thermoplastic polymer at the melting temperature of the polymer but phase separates on cooling at or below the crystallization temperature of the polymer, forming a shaped article of the melt blend, cooling the shaped article to a temperature at which the polymer crystallizes to cause phase separation to occur between the thermoplastic polymer and the compound to provide an article comprising a first phase comprising particles of crystallized thermoplastic polymer in a second phase of said compound, orienting the article in at least one direction to provide a network of interconnected micropores throughout. The microporous article comprises about 30 to 80 parts by weight crystallizable thermoplastic polymer and about 70 to 20 parts by weight of the compound. The oriented article has a microporous structure characterized by a multiplicity of spaced randomly dispersed, equiaxed, non-uniform shaped particles of the thermoplastic polymer which are coated with the compound. Adjacent thermoplastic particles within the article are connected to each other by a plurality of fibrils consisting of the thermoplastic polymer. The fibrils radiate in three dimensions from each particle. The compound may be removed from the sheet article. e.g., by solvent extraction. The preferred article is a sheet material.