Dried semipermeable membrane and manufacture thereof

Details Dried semipermeable membrane and manufacture thereof Dried semipermeable membrane and manufacture thereof

1975-10-09

1977-05-24

Thurlow, Jeffery R.

Liquid purification or separation

Filter

Material

264 41, 264 49, 264206, 264234, 264345, B01D 1304

Patent

active

040254399

ABSTRACT:
Dry semipermeable membranes of polyacrylonitrile or copolymers containing more than 65 wt. % of acrylonitrile are prepared by dissolving the polymer in a solvent in a solids concentration of 15-30% by weight; uniformly coating the solution onto a surface in a desired shape under an atmosphere whose relative humidity is 60-85% and dipping said coated surface into a non-solvent medium so as to remove the solvent which forms the membrane; heat-treating the membrane under moist conditions at 60.degree.-90.degree. C; and drying the membrane at a temperature less than the temperature of the heat treatment under conditions such that the coefficient of contraction is less than 1%, whereby a dried semi-permeable membrane having an open-celled structure with a pore size of a diameter less than 0.5 .mu. and a porosity of 0.40-0.7 is obtained.

REFERENCES:
patent: 2649427 (1953-08-01), Marvel
patent: 3567810 (1971-03-01), Baker
patent: 3615024 (1971-10-01), Michaels
patent: 3616930 (1971-11-01), Muir
patent: 3718722 (1973-02-01), Lee
patent: 3822330 (1974-07-01), Muir et al.
patent: 3917777 (1975-11-01), Asada et al.
patent: 3933653 (1976-01-01), Hashino et al.
"Drying Cellulose Acetate Membranes,"-Vos et al., I & EC Product Research and Development, vol. 8, No. 1, Mar. 1969, pp. 84-89.
"R & D of New Polymer Systems for R.O. Membranes," Saltonstall et al., Research & Development Progress Report No. 167, 2-1966, pp. 9-10.

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