Polyamide membrane with controlled surface properties
First Claim
1. A process for preparing a surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane with controlled pore surface properties, capable of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b) and that is readily wetted by water, which comprises:
- (1) preparing a casting solution comprised of (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin having a ratio CH2 ;
NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, and (b) a water-soluble, membrane surface modifying polymer having functional polar groups selected from the group consisting of hydroxyl, carboxyl, and amino or a non-reacting combination thereof, and a molecular weight of 20,000 or greater, and (B) a solvent system in which said casting resin system is soluble;
(2) inducing nucleation of said casting solution by controlled addition of nonsolvent 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 thin film thereof on the substrate;
(4) contacting and diluting the film of said casting composition with a liquid nonsolvent system for said casting resin system comprised of a mixture of solvent and nonsolvent liquids, thereby precipitating said casting resin system from said casting composition in the form of a thin, skinless, hydrophilic, surface modified, microporous, polyamide membrane with controlled surface properties;
(5) washing said membrane to remove solvent; and
(6) drying said membrane.
0 Assignments
0 Petitions
Accused Products
Abstract
Surface modified, skinless, hydrophilic, microporous, polyamide membranes with controlled surface properties are prepared by the steps of preparing a casting solution comprised of (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin, and (b) a water-soluble membrane surface modifying polymer having functional polar groups and a molecular weight of 10,000 or greater, and (B) a solvent system in which the casting resin system is soluble; inducing nucleation of the casting solution by controlled addition of a nonsolvent 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 nonsolvent 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 surface properties thereof being substantially controlled by functional polar groups of a membrane surface modifying polymer and having the capability, through the functional polar groups of the modifying polymer, of reacting or interacting with particulates and/or nonparticulates in a fluid.
-
Citations
65 Claims
-
1. A process for preparing a surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane with controlled pore surface properties, capable of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b) and that is readily wetted by water, which comprises:
-
(1) preparing a casting solution comprised of (A) a casting resin system comprised of (a) an alcohol-insoluble polyamide resin having a ratio CH2 ;
NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, and (b) a water-soluble, membrane surface modifying polymer having functional polar groups selected from the group consisting of hydroxyl, carboxyl, and amino or a non-reacting combination thereof, and a molecular weight of 20,000 or greater, and (B) a solvent system in which said casting resin system is soluble;(2) inducing nucleation of said casting solution by controlled addition of nonsolvent 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 thin film thereof on the substrate; (4) contacting and diluting the film of said casting composition with a liquid nonsolvent system for said casting resin system comprised of a mixture of solvent and nonsolvent liquids, thereby precipitating said casting resin system from said casting composition in the form of a thin, skinless, hydrophilic, surface modified, microporous, polyamide membrane with controlled surface properties; (5) washing said membrane to remove solvent; and (6) drying said membrane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A process for preparing a surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyhexamethylene adipamide resin membrane with controlled pore surface properties, capable of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b) and that is readily wetted by water, which comprises:
-
(1) preparing a casting solution comprised of (A) a casting resin system comprised of (a) an alcohol-insoluble polyhexamethylene adipamide resin in a concentration within the range from about 10% to about 20% by weight and (b) a water-soluble, membrane surface modifying polymer having functional polar groups selected from the group consisting of hydroxyl, carboxyl, and amino or a non-reacting combination thereof, and a molecular weight of from about 25,000 to about 150,000 in a concentration within the range of from about 0.5% to about 3% and (B) a solvent system comprised of (a) formic acid in a concentration of from about 60% to about 80% and (b) from 0% to about 30% water, all percentages based on the weight of all the components in said casting solution; (2) inducing nucleation of said casting solution by adding water thereto while controlling temperature, rate of addition of water 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 thin film of said casting composition thereon; (4) contacting and diluting said thin film of said casting composition with an aqueous solution containing from about 35% to about 60% formic acid, thereby precipitating said casting resin system from said casting composition as a thin, surface modified, skinless, hydrophilic, microporous, polyamide membrane; (5) washing said membrane to remove formic acid; and (6) drying said membrane. - View Dependent Claims (23, 24, 25)
-
-
26. A surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane derived from an alcohol-insoluble hydrophobic polyamide resin having a ratio CH2 :
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, said membrane having an integral microstructure and characterized by (1) the surface properties thereof being substantially controlled by functional polar groups of a membrane surface modifying polymer having a molecular weight of 20,000 or greater, said functional polar groups selected from the group consisting of hydroxyl, carboxyl, and amino, or a non-reacting combination thereof, (2) said membrane surface modifying polymer being homogeneously distributed in said membrane, and (3) having the capability of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b). - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
-
55. An integral surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane derived from about 80 to about 99.9% of an alcohol-insoluble hydrophobic polyamide resin having a ratio CH2 :
- NHCO of methylene CH2 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 membrane surface modifying polymer having functional polar groups, said functional polar groups selected from the group consisting of hydroxyl, carboxyl, and amino, or a nonreacting combination thereof, and a molecular weight of 20,000 or greater, said membrane having an integral microstructure and characterized by (1) the surface properties thereof being substantially controlled by functional polar groups of the membrane surface modifying polymer, (2) said membrane surface modifying polymer being homogeneously distributed in said membrane, and (3) having the capability of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b). - View Dependent Claims (56, 57, 58, 59, 60, 61, 62)
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
-
63. A surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane derived from an alcohol-insoluble hydrophobic polyamide resin having a ratio CH2 :
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, said membrane having an integral microstructure and characterized by (1) the surface properties thereof being substantially controlled by functional polar groups of a membrane surface modifying polymer having a molecular weight of 20,000 or greater, said functional polar groups comprising hydroxyl, (2) said membrane surface modifying polymer being homogeneously distributed in said membrane, and (3) having the capability of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b).
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
-
64. A surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane derived from an alcohol-insoluble hydrophobic polyamide resin having a ratio CH2 :
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, said membrane having an integral microstructure and characterized by (1) the surface properties thereof being substantially controlled by functional polar groups of a membrane surface modifying polymer having a molecular weight of 20,000 or greater, said functional polar groups comprising carboxyl, (2) said membrane surface modifying polymer being homogeneously distributed in said membrane, and (3) having the capability of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b).
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
-
65. A surface modified, skinless, hydrophilic, microporous, alcohol-insoluble polyamide membrane derived from an alcohol-insoluble hydrophobic polyamide resin having a ratio CH2 :
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
1 to about 7;
1, said membrane having an integral microstructure and characterized by (1) the surface properties thereof being substantially controlled by functional polar groups of a membrane surface modifying polymer having a molecular weight of 20,000 or greater, said functional polar groups comprising amino, (2) said membrane surface modifying polymer being homogeneously distributed in said membrane, and (3) having the capability of reacting or interacting in a controlled manner with (a) particulate matter in a fluid, (b) non-particulate matter in a fluid, or (c) both (a) and (b).
- NHCO of methylene CH2 to amide NHCO groups within the range of from about 5;
Specification