Microporous polymeric membrane
AssigneeAbcor, Inc.
InventorsStephen Z. Jakabhazy, Leos J. Zeman
Life of this patent
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Abstract
A microporous polymeric membrane is made by preparing a polymer-casting solution, casting a thin film of the casting solution on a support base, allowing partial evaporation of the solvent from the cast film for a predetermined period of time and contacting the partially evaporated film with a leaching liquid to provide the microporous membrane. A membrane with particularly good mechanical strength and hydrophilic properties is formed when the casting solution comprises a vinylidene fluoride polymer and from about 35 to about 85% by weight of a vinyl acetate polymer; and when the acetate polymer is hydrolyzed after the leaching step to convert the acetate groups to hydroxyl groups.
Claims23
An alloy membrane of good mechanical strength and hydrophilic properties, which membrane comprises a hydrophobic fluorocarbon matrix polymer intimately blended with from about 20% to about 75% by weight of an aqueous, nonleachable polyvinyl alcohol polymer.
An alloy membrane of good mechanical strength and hydrophilic properties, which membrane comprises a hydrophobic vinylidene fluoride matrix polymer intimately blended with from about 20% to 75% by weight of an aqueous, nonleachable polyvinyl alcohol polymer.
A film adapted to be converted by hydrolysis to a membrane film of good mechanical strength and hydrophilic properties, which film comprises a fluorocarbon polymer intimately blended with from about 35% to 85% by weight of a hydrolyzable vinyl-acetate polymer.
A film adapted to be converted by hydrolysis to a membrane film of good mechanical strength and hydrophilic properties, which film comprises a vinylidene fluoride polymer intimately blended with from about 60% to 80% by weight of a hydrolyzable vinyl-acetate polymer.
A casting solution adapted to be evaporated partially to form a film for subsequent conversion into a hydrophilic membrane by leaching and hydrolysis, which casting solution comprises a polyvinylidene fluoride polymer, from about 35% to 85% by weight of a vinyl-acetate polymer, an aprotic polar solvent and a diluent, the solvent being selected from the group consisting of dimethyl acetamide, dimethyl formamide, N-methyl pyrrolidone, dimethyl sulfoxide and acetone.
Dependencies are inferred from the claim text.