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US 5,164,088 AGranted
Multilayer membrane and process of manufacturing same
AssigneeMetallgesellschaft Aktiengesellschaft
Inventors/Peter Hanel, Harald Helmrich
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AssigneeMetallgesellschaft Aktiengesellschaft
Inventors/Peter Hanel, Harald Helmrich
Estimating the term…
The process of making a multilayer membrane composed of a carrier layer, a porous supporting layer and a separating layer includes making a modified polyvinyl alcohol by decomposing a polyvinyl ester or ether until the proportion of the vinyl alcohol monomer units in the modified polyvinyl alcohol corresponds to that in a material consisting of 80 to 95% of the polyvinyl ester or ether and 20 to 5% of a polyvinyl alcohol obtained by completely decomposing the polyvinyl ester or ether; preparing a composite material consisting of the carrier layer and the porous supporting layer, preparing a dilute aqueous solution containing 1 to 10% by weight of the modified polyvinyl alcohol; preferably storing the dilute solution at temperatures from -10.degree. to +10.degree. C., preferably from 0.degree. to 5.degree. C., for 3 to 20 days, after storing, applying the dilute solution to the supporting layer of the composite material to coat the composite material with the modified polyvinyl alcohol; and after the applying, heating the composite material coated with the modified polyvinyl alcohol at a temperature of from 100.degree. to 180.degree. for 1 to 60 minutes.
In a multilayer membrane composed of a carrier layer, a porous supporting layer and a separating layer, the improvement wherein said carrier layer consists essentially of fibers of a material selected from the group consisting of polyamide, polyvinylidene difluoride, polyester and glass, the porous supporting layer consists essentially of a member selected from the group consisting of polysulfone, polyvinylidene difluoride, polyethersulfone, polyimide, polyvinyl alcohol, polyurethane, polyacrylonitrile and polyether imide, and the separating layer consists essentially of a nonporous material made of a modified polyvinyl alcohol consisting essentially of a copolymer of vinyl alcohol and a member selected from the group consisting of vinyl ethers and vinyl esters, so that said copolymer contains vinyl alcohol monomer units and vinyl ether or ester monomer units, the proportion of the vinyl alcohol monomer units in the modified polyvinyl alcohol corresponding to that in a material consisting of 95 to 80% of polyvinyl alcohol and 5 to 20% by weight of a polyvinyl ester or ether made by polymerizing the vinyl ester or ether used to make the copolymer.
A process of making a multilayer membrane composed of a carrier layer, a porous supporting layer and a separating layer, the process comprising the steps of:
In a multilayer membrane composed of a carrier layer consisting of fibers of a material selected from the group consisting of polyamide, polyvinylidene difluoride, polyester and glass;
Dependencies are inferred from the claim text.