Microporous polyolefin membranes from bespoke solvents
AssigneeAmtek Research International LLC
InventorsWeston J. Wood, Don Spitz, Matthew Alan Warren, Cory S. Rogers, Richard W. Pekala
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Abstract
Halogen-free, microporous polyolefin membranes are disclosed herein. The halogen-free, microporous polyolefin membranes can be manufactured using an environmentally friendly manufacturing process that includes extrusion of polymer-plasticizer mixtures followed by sheet formation and extraction of the plasticizer with a halogen-free solvent. The halogen-free solvent has a flashpoint greater than about 23° C. and an initial boiling point at least about 50° C. lower than the flashpoint of the plasticizer. The process can further be a closed loop process in which the halogen-free solvent can be reused.
Claims21
A method for the manufacture of a microporous polyolefin membrane, comprising:
- melt blending a polyolefin and a plasticizer to form a mixture;
- casting or extruding the mixture into a non-porous sheet;
- cooling the non-porous sheet to induce phase separation of the polyolefin and plasticizer;
- and
- extracting the plasticizer from the non-porous sheet with a halogen-free solvent and evaporating the solvent to form a microporous polyolefin membrane, wherein the halogen-free solvent comprises a flashpoint above about 23° C. with an initial boiling point at least about 50° C. lower than a flashpoint of the plasticizer;
- wherein the method is performed using a closed-loop, solvent extraction, drying, and solvent recovery system.
A method for the manufacture of a microporous polyolefin membrane, comprising:
- melt blending a polyolefin and a plasticizer to form a mixture;
- casting or extruding the mixture into a non-porous sheet;
- cooling the non-porous sheet to induce phase separation of the polyolefin and plasticizer;
- and
- extracting the plasticizer from the non-porous sheet with a halogen-free solvent and evaporating the solvent to form a microporous polyolefin membrane, wherein the halogen-free solvent comprises an isoparaffin having a flashpoint of about 38° C. to about 66° C. with an initial boiling point at least about 50° C. lower than a flashpoint of the plasticizer.
Dependencies are inferred from the claim text.