Pourous fluorocarbon membrane, method for producing thereof and cartridge filter based on said membrane
First Claim
1. A porous fluorocarbon membrane comprisinga porous support and a layer of fluorocarbon polymer connected to said porous support, said porous support having an average pore size ranging from 5.0 to 500.0 microns and difference by specific weight in any two points of a sample having various sizes of not more than 7%;
- said porous support is completely impregnated with a copolymer solution soluble in organic solvent wherein the copolymer is consisting of 23-25 weight percent tetrafluoroethylene and 75-77 weight percent vinylidene fluoride,the ratio of viscosity of the copolymer solution in acetone, with copolymer content in the solution in the amount of 0.01 g/cm3, to acetone equal to 2.0-4.0.
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Abstract
A porous fluorocarbon membrane has a porous support completely impregnated with tetrafluoroethylene/vinylidene fluoride copolymer. There is a process for producing this membrane by impregnating a porous support with a copolymer solution in a readily-boiling solvent and a precipitating mixture of alcohol and water followed by curing for partial hardening of the solution and subsequent drying at elevated temperature. A cartridge filter includes protective and supporting cylindrical perforated hollow housings, containing a fluorocarbon membrane or two superimposed flourocarbon membranes. Membranes and a cartridge filter find extensive use in separation of gases and aggressive media.
96 Citations
18 Claims
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1. A porous fluorocarbon membrane comprising
a porous support and a layer of fluorocarbon polymer connected to said porous support, said porous support having an average pore size ranging from 5.0 to 500.0 microns and difference by specific weight in any two points of a sample having various sizes of not more than 7%; -
said porous support is completely impregnated with a copolymer solution soluble in organic solvent wherein the copolymer is consisting of 23-25 weight percent tetrafluoroethylene and 75-77 weight percent vinylidene fluoride, the ratio of viscosity of the copolymer solution in acetone, with copolymer content in the solution in the amount of 0.01 g/cm3, to acetone equal to 2.0-4.0. - View Dependent Claims (2)
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3. A method for producing a porous fluorocarbon membrane by dissolving tetrafluoroethylene/vinylidene fluoride copolymer in an organic readily-boiling solvent, mixing the resultant copolymer solution with a precipitating mixture to produce a casting solution, forming said casting solution into a membrane on a continuously moving carrying surface and drying the resulting continuously moving membrane at elevated temperature, wherein porous material having the average pore size within the range of 5.0-500.0 microns and difference by specific weight in any two points of a sample having various sizes of not more than 7% is used as a carrying surface;
- formation is performed by the complete impregnation of porous material moving at a constant speed with heated casting solution of a copolymer comprising 23-25 tetrafluoroethylene and 75-77 weight percent vinylidene fluoride and having the ratio of viscosity of the copolymer solution in acetone, with copolymer content in the solution in the amount of 0.01 g/cm3, to acetone equal to 2.0-4.0;
short-term storage of continuously moving porous material while applying the casting solution under the conditions of free evaporation of a portion of solvent for partial hardening of the casting solution and consequent drying of continuously moving porous material is effected in at least three successive drying zones wherein temperature, increasing from one zone to another, is maintained. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- formation is performed by the complete impregnation of porous material moving at a constant speed with heated casting solution of a copolymer comprising 23-25 tetrafluoroethylene and 75-77 weight percent vinylidene fluoride and having the ratio of viscosity of the copolymer solution in acetone, with copolymer content in the solution in the amount of 0.01 g/cm3, to acetone equal to 2.0-4.0;
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15. A cartridge filter comprising
protective and supporting cylindrical perforated hollow housings, a pleated porous membrane provided with a prefiltration device and a drainage placed between said housings and tightly connected to the cases of end caps, at least one said end caps having a central drain duct, said cartridge filter further comprises a membrane consisting of a porous support having an average pore size within the range of 5.0-500.0 microns and the difference by specific weight in any two points of a sample having various sizes of 7.0% max., which porous support is completely impregnated with a copolymer solution soluble in organic solvent wherein the copolymer solution containing 23-25% by weight tetrafluoroethylene and 75-77% by weight vinylidene fluoride and having the ratio of viscosity of the solution thereof in acetone, with copolymer content in solution in the amount of 0.01 g/cm3 to acetone equal to 2.0 to 4.0.
Specification