BIAXIALLY ORIENTED POROUS MEMBRANES, COMPOSITES, AND METHODS OF MANUFACTURE AND USE

• Main Authors: BRASWELL, Michael, A, PROCTOR, Ronald, A, FIELDS, Tyrone, S, ZHANG, Xiaomin, RUMIERZ, Gerald, P, HUMISTON, Karl, F, HAIRE, Charles, E
• Format: Patent
• Language: English; French; German
• Published: 07.07.2021
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; BASIC ELECTRIC ELEMENTS; BORING; CHEMISTRY; COMPOSITIONS BASED THEREON; ELECTRICITY; INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULARARTICLES; MACHINE TOOLS; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY; SEPARATION; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; TURNING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

At least a selected microporous membrane is made by a dry-stretch process and has substantially round shaped pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 6.0. The method of making the foregoing microporous membrane may include the steps of: extruding a polymer into a nonporous precursor, and biaxially stretching the nonporous precursor, the biaxial stretching including a machine direction stretching and a transverse direction stretching, the transverse direction including a simultaneous controlled machine direction relax. At least selected embodiments of the invention may be directed to biaxially oriented porous membranes, composites including biaxially oriented porous membranes, biaxially oriented microporous membranes, biaxially oriented macroporous membranes, battery separators, filtration media, humidity control media, flat sheet membranes, liquid retention media, and the like, related methods, methods of manufacture, methods of use, and the like.