EP0090483A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Polyamide membrane and process for its production
Assignee: Pall Corp
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Filing: 1983-02-02
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Granted: —
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Expires: 2003-02-02
Abstract
Abstract Surface modified, skinless, hydrophilic, microporous, polyamide membranes are formed by preparing a casting solution comprised of (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin, and (b) a cationic, water-soluble, quaternary ammonium, thermosetting, membrane surface modifying polymer, and (B) a solvent system in which the casting resin system is soluble; inducing nucleation of the casting solution by controlled addition of a non-solvent for the casting resin system under controlled conditions to obtain a visible precipitate of casting resin system particles, thereby forming a casting composition; spreading the casting composition on a substrate to form a thin film; contacting and diluting the film of the casting composition with a liquid non-solvent system for the casting resin system, thereby precipitating the casting resin system from the casting composition in the form of a thin, skinless, hydrophilic, surface modified, microporous, polyamide membrane; and washing and drying the membrane. The membranes of this invention are characterized by having fine pore ratings, the surfaces thereof being substantially completely covered by the modifying polymer, a positive zeta potential in alkaline media, and for those with moderate or low levels of surface modifying polymer present, a time to reach an effluent resistivity of 14 megaohms/ cm under the Resistivity Test of 10 minutes or less. They have greatly enhanced filtration efficieny over a broad pH range with a variety of contaminants, including very fine negatively charged particles, bacteria and endotoxins.
Inventors
- 👤 Thomas Charles Gsell
- 👤 Irving Brian Joffee
- 👤 Peter John Degen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:00
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/56; B01D39/00; B01D39/14; B01D39/16; B01D67/00; B01D67/0002; B01D67/0009; B01D67/0011; B01D2323/00; B01D2323/12; B01D2323/30; B01D2325/00; B01D2325/36
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
213 words
A process for preparing a polyamide membrane that is readily wetted by water which process is characterized by the steps of: (1) preparing a casting solution including (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin having a ratio (CH 2 :NHCO) of methylene CH 2 to amide NHCO groups within the range of from 5:1 to 7:1, and (b) a cationic, water-soluble quaternary ammonium, thermosetting, membrane-surface-modifying polymer and (B) a solvent system in which said c.asting resin system is soluble; (2) inducing nucleation of said casting solution by controlled addition of a non-solvent for said casting resin system under controlled conditions of concentration, temperature, addition rate and degree of agitation to obtain a visible precipitate of casting resin system particles, thereby forming a casting composition; (3) spreading said casting composition on a substrate to form a film thereof on the substrate; (4) contacting and diluting the film of said casting composition with a liquid non-solvent system for said casting resin system comprised of a mixture of solvent and non-solvent liquids, thereby precipitating on to the substrate said casting resin system from said casting composition in the form of a thin, skinless, hydrophilic, surface-modified, microporous, polyamide membrane; (5) washing said membrane to remove the solvent: and (6) drying said membrane.
Claim 2
Dependent Claim
213 words
A process for preparing a polyamide membrane that is readily wetted by water which process is characterized by the steps of: (1) preparing a casting solution including (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin having a ratio (CH 2 :NHCO) of methylene CH 2 to amide NHCO groups within the range of from 5:1 to 7:1, and (b) a cationic, water-soluble quaternary ammonium, thermosetting, membrane-surface-modifying polymer and (B) a solvent system in which said c.asting resin system is soluble; (2) inducing nucleation of said casting solution by controlled addition of a non-solvent for said casting resin system under controlled conditions of concentration, temperature, addition rate and degree of agitation to obtain a visible precipitate of casting resin system particles, thereby forming a casting composition; (3) spreading said casting composition on a substrate to form a film thereof on the substrate; (4) contacting and diluting the film of said casting composition with a liquid non-solvent system for said casting resin system comprised of a mixture of solvent and non-solvent liquids, thereby precipitating on to the substrate said casting resin system from said casting composition in the form of a thin, skinless, hydrophilic, surface-modified, microporous, polyamide membrane; (5) washing said membrane to remove the solvent: and (6) drying said membrane.
Claim 3
Dependent Claim
24 words
A process according to claim 1 characterized in that precipitated casting resin system particles are redissolved before spreading said casting composition on said substrate.
Claim 4
Dependent Claim
25 words
A process according to claim 1 characterized in that precipitated casting resin system particles are filtered out before spreading said casting composition on said substrate.
Claim 5
Dependent Claim
24 words
A process according to any one of claims 1 to 3 characterized in that said polyamide resin is polyhexamethylene adipamide, poly-e-caprolactam, or polyhexamethylene sebacamide.
Claim 6
Dependent Claim
34 words
A process according to any one of claims 1 to 4 characterized in that said solvent system for said casting resin system comprises formic acid, and said non-solvent added to induce nucleation is water.
Claim 7
Dependent Claim
27 words
A process according to any one of claims 1 to 5 characterized in that said solvent system for said casting resin system comprises formic acid and water.
Claim 8
Dependent Claim
25 words
A process according to any of claims 1 to 6 characterized in that said membrane-surfacing-modifying polymer is a polyamine epichlorohydrin polymer, or a polyamido/polyamino-epichlorohydrin polymer.
Claim 9
Dependent Claim
83 words
A process according to any one of claims 1 to 7 characterized in that said casting composition is continuously spread onto said substrate, said film of said casting composition is continuously immersed in a bath of said liquid non-solvent system, and the bath is maintained at a substantially constant composition with respect to non-solvent and solvent by the addition of non-solvent to the bath in a quantity sufficient to compensate for solvent diffusion into the bath from said film of said casting composition.
Claim 10
Dependent Claim
42 words
A process according to claim 8 characterized in that the substrate is a porous web having an open structure which is wetted and impregnated by the casting composition, thereby forming a membrane film having the porous web incorporated as a part thereof.
Claim 11
Dependent Claim
99 words
A surface-modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane characterized in that it is derived from an alcohol-insoluble, hydrophobic, polyamide resin having a ratio (CH Z :NHCO) of methylene CH 2 to amide NHCO groups within the range of from 5:1 to about 7:1, said membrane having (1) the surface properties thereof substantially controlled by cationic, quaternary ammonium groups of a cationic, quaternary ammonium, thermoset, surface-modifying polymer, thereby providing a positive zeta potential in alkaline media, and (2) a time to reach an effluent resistivity of 14 megaohms/cm under the Resistivity Test (as hereinbefore defined) of 10 minutes or less.
Claim 12
Dependent Claim
99 words
A surface-modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane characterized in that it is derived from an alcohol-insoluble, hydrophobic, polyamide resin having a ratio (CH Z :NHCO) of methylene CH 2 to amide NHCO groups within the range of from 5:1 to about 7:1, said membrane having (1) the surface properties thereof substantially controlled by cationic, quaternary ammonium groups of a cationic, quaternary ammonium, thermoset, surface-modifying polymer, thereby providing a positive zeta potential in alkaline media, and (2) a time to reach an effluent resistivity of 14 megaohms/cm under the Resistivity Test (as hereinbefore defined) of 10 minutes or less.
Claim 13
Dependent Claim
26 words
A membrane according to claim 10 characterized in that it has through pores extending from surface to surface that are substantially uniform in shape and size.
Claim 14
Dependent Claim
41 words
A membrane according to claim 10 characterized in that it has through pores extending from surface to surface that are tapered, being wider at one surface of the sheet and narrowing as they proceed toward the opposite surface of the membrane.
Claim 15
Dependent Claim
18 words
A membrane according to any one of claims 10 12 characterized in that said polyamide resin is polyhexamethylene.adipamide.
Claim 16
Dependent Claim
33 words
An assembly comprising membranes according to any one of claims 10 to 13 characterized by two or more of said membranes secured to each other and forming a multiple layer membrane filter sheet.
Claim 17
Dependent Claim
96 words
An integral, surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane characterized in that the membrane is derived from about 80 to about 99.9% of an alcohol-insoluble, hydrophobic polyamide resin having a ratio CH 2 :HNCO of methylene CH 2 to amide NHCO groups within the range of from about 5:1 to about 7:1 and from about 20 to about 0.1% of a cationic, quaternary ammonium, thermoset, surface modifying polymer, the surface properties of the membrane being substantially controlled by cationic, quaternary ammonium groups of said modifying polymer, thereby providing a positive zeta potential in alkaline media.
Claim 18
Dependent Claim
96 words
An integral, surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane characterized in that the membrane is derived from about 80 to about 99.9% of an alcohol-insoluble, hydrophobic polyamide resin having a ratio CH 2 :HNCO of methylene CH 2 to amide NHCO groups within the range of from about 5:1 to about 7:1 and from about 20 to about 0.1% of a cationic, quaternary ammonium, thermoset, surface modifying polymer, the surface properties of the membrane being substantially controlled by cationic, quaternary ammonium groups of said modifying polymer, thereby providing a positive zeta potential in alkaline media.
References Cited (Backward Citations)
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