Microporous materials and methods of making
OwnerRobert Floyd, Randall Swenson +1inventors
InventorsRobert Floyd, Randall Swenson, James Mrozinski
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Abstract
Microporous materials and articles are disclosed. The microporous materials contain a polyolefin or olefinic polymer and a solid diluent in which the polymer is soluble at a temperature above the melting temperature of the polymer and that phase separates from the polymer at a temperature below the polymer crystallization temperature. The resulting material is a microporous material having a polymeric matrix with solid diluent present throughout. The invention is also directed to methods of forming the microporous material using thermally induced phase separation and subsequent processing.
Claims27
A microporous material comprising:
- (a) a matrix of polyolefin domains interconnected by polyolefin fibrils;
- and
- (b) solid diluent present between the domains, the solid diluent being miscible with the polyolefin at a temperature above the melting temperatures of the polyolefin and the solid diluent and phase separating from the polymer at a temperature below the polymer crystallization temperature.
A method of making a microporous article, consisting of:
- (a) melt blending to form a solution comprising a melted polyolefin polymer component and a melted solid diluent component, the melted polymer component being soluble in the melted solid diluent component;
- (b) forming an article from the melt blended solution;
- (c) cooling the article to crystallize the melted polyolefin polymer component and form a matrix of polymer domains and to solidify the melted solid diluent component as solid diluent distributed among the polymer domains;
- and
- (d) creating porosity by stretching the article in at least one direction to separate adjacent polymer domains from each other and to provide a network of interconnected micropores therebetween, the resulting article comprising polyolefin polymer domains at least partially surrounded by solid diluent.
A method of making a microporous article, comprising:
- (a) melt blending to form a solution comprising a melted polyolefin polymer component and a melted solid diluent component, the melted polymer component being soluble in the melted solid diluent component;
- (b) forming an article of the melt blended solution;
- (c) cooling the article to crystallize the melted polyolefin polymer component and form a matrix of polymer domains and to solidify the melted solid diluent component as wax distributed among the polymer domains;
- and
- (d) creating porosity by stretching the article in at least one direction to separate adjacent polymer domains from each other and to provide a network of interconnected micropores therebetween, the resulting article comprising polyolefin polymer domains at least partially surrounded by solid diluent.
Dependencies are inferred from the claim text.