CA2081260A1 - Semipermeable, porous, asymmetric polyether amide membranes - Google Patents
Semipermeable, porous, asymmetric polyether amide membranesInfo
- Publication number
- CA2081260A1 CA2081260A1 CA002081260A CA2081260A CA2081260A1 CA 2081260 A1 CA2081260 A1 CA 2081260A1 CA 002081260 A CA002081260 A CA 002081260A CA 2081260 A CA2081260 A CA 2081260A CA 2081260 A1 CA2081260 A1 CA 2081260A1
- Authority
- CA
- Canada
- Prior art keywords
- membrane
- iii
- polyaramide
- structural units
- liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/52—Polyethers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
- C08G69/265—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from at least two different diamines or at least two different dicarboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/40—Polyamides containing oxygen in the form of ether groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/42—Polyamides containing atoms other than carbon, hydrogen, oxygen, and nitrogen
Abstract
Abstract of the disclosure:
Semipermeable, porous, asymmetric polyether amide membranes 1. A semipermeable, porous, asymmetric membrane, which contains a polyaramide which contains one or more of the recurring structural units of the formula (I) (I) and, based on the sum of (II) and (III), up to 15 to 100 molar % of structural units of the formula (II) (II) and, based on the sum of (II) and (III), up to 0 to 85 molar % of structural units of the formula (III) (III) where the ratio of the sum of (II) and (III) to (I) is 0.90 to 1.10, and the symbols -Ar-, -X- and -Y-have the following meaning:
-Ar- is a divalent, aromatic or heteroaromatic radical, where the two carbonyl groups of the Ar radical are located on unadjacent ring carbon atoms (i.e. in para- or meta-position) and the Ar radical is unsubstituted or substituted by one or two branched or unbranched C1-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radicals or C1-C6-perfluoroalkyl or C1-C6-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine;
-X- is a group -C(CH3)2-, -C(CF3)2-, -CO-, -SO-, -SO2-, -CH2-, -S- or -O- or a direct bond and -Y- is a group -SO2-, , -CH2-, -O-, -S--C(CH3)2-, or -C(CF3)2- or a direct bond.
The polyaramide has a Staudinger index in the range of 50 to 1090 cm3/g, preferably of 100 to 500 cm3/g. In a preferred instance, the membrane i arranged on a support layer, permeable for flowable media, composed of plastic nonwoven web, for example of polyethylene terephthalate or polypropylene, or is arranged on a fabric.
Semipermeable, porous, asymmetric polyether amide membranes 1. A semipermeable, porous, asymmetric membrane, which contains a polyaramide which contains one or more of the recurring structural units of the formula (I) (I) and, based on the sum of (II) and (III), up to 15 to 100 molar % of structural units of the formula (II) (II) and, based on the sum of (II) and (III), up to 0 to 85 molar % of structural units of the formula (III) (III) where the ratio of the sum of (II) and (III) to (I) is 0.90 to 1.10, and the symbols -Ar-, -X- and -Y-have the following meaning:
-Ar- is a divalent, aromatic or heteroaromatic radical, where the two carbonyl groups of the Ar radical are located on unadjacent ring carbon atoms (i.e. in para- or meta-position) and the Ar radical is unsubstituted or substituted by one or two branched or unbranched C1-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radicals or C1-C6-perfluoroalkyl or C1-C6-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine;
-X- is a group -C(CH3)2-, -C(CF3)2-, -CO-, -SO-, -SO2-, -CH2-, -S- or -O- or a direct bond and -Y- is a group -SO2-, , -CH2-, -O-, -S--C(CH3)2-, or -C(CF3)2- or a direct bond.
The polyaramide has a Staudinger index in the range of 50 to 1090 cm3/g, preferably of 100 to 500 cm3/g. In a preferred instance, the membrane i arranged on a support layer, permeable for flowable media, composed of plastic nonwoven web, for example of polyethylene terephthalate or polypropylene, or is arranged on a fabric.
Description
~ Jr~ r~
HOECHST AKTIENGESELLSCHAFT HOE 91/F 336 Dr. MI
Description Semipermeable, poxou , asymmetric polyether amide membranes Since the introduction of asymmetric membranes of cel-lulose acetate by Loeb and Sourixajan ~S. Sourixajan, Reverse Osmosis, Logos Press, London 1970) and of hydro-phobic polymers (~S Patent 3,615,024) a number of membrane have been developed and proposed, in particular for separation of low and high molecular constituent~
dissolved in water, the ~tructure and suitability of which are given in the literature (Desali~ation, 35 (1980), 5-20) and which have also been successfully tested in industrial practice or for clinical purposes.
Many of the membranes described have particularly advan-tageous properties for achieving specific tasks. As a result of their chemical constitution and their struc-ture, each individual membrane can be optimally suited only for quite ~pecific separation problems. From this results the fundamental requirement of continuously developing new membranes for new tasks.
EP-A 0 082 4~3 gives an overview of the advantages and di~advantages of membrane~ which are already known. Thus, for example, there are hydrophilic, asymmetric membranes of cellulose acetate having satisfactory antiadsorptive properties, but whose thermal and chemical stability leave a lot to be desired. Membranes of poly~ulfones or similar polymers do posse~s a good thermal and chemical stability, but such membranes, because of the hydrophobic properties of the polymer~ used, show a pronounced tendency to adsorb dissolved Rubsta~ces, as a result of which the membrane is blocked. The mixtures of polysulfone and polyvinylpyrrolidone di3closed in EP-A 0 082 433 do dispose of the disadvantage resulting from the hydrophobicity of the polysulfone, but these - 2 ~ t~
mixtures are sen3iti.ve to the action of organic solvent~.
Hydrophilicity and simultaneous resistance to solvents are found in membranes of regenerated cellulose; but these can be relatively easily hydrolyzed in acid or alkaline media/ and moreover they are easily attacked by microorganisms.
It is therefore an ob~ect of the invention to provide semipermeable, porous asymmetric membranes which are stable to chemical and thermal action, which can be prepared by a simple and economical method and wbose membrane properties can be easily varied according to the area of application.
This object is achieved by a semipermeable, porous, asymmetric membrane whose distinguishin~ features are that it contains a polyaramide which contains one or more of the recurring structural units of the formula (I) O O
¦¦ ll (I) -~-Ar-C-and, based on the sum of (II) and (III), up to 15 to 100 molar ~ of structural units of the formula (II) ~ u ~ ~ ~~ (II) and, based on the sum of (II) and (III), up to 0 to 85 molar % of structural units of the formula (III) -NH~ ~NH-( I I I ) where the ratio of the sum of (II) and (III) to (I) i5 0.90 to 1.10, but preferably 1~0 and the ~ymbols -AI-, -X- and -Y- have the following - 3 ~ p~.,~
meaning:
-Ar- i8 a divalent, aromatic or heteroaromatic radical, where the two ca.rbonyl gra,up~ are located on unad~acent ring carbon atom~ (.i.e. in para- or meta-position) and the Ar rsdical is un~ub~tituted or substituted by one or ~wo branched or unbranched C~-C3-alkyl or C~-C3-alkoxy radicals, aryl or aryloxy radical~ or Cl-C6 perfluoroalkyl or C~C6-perfluoro-alkoxy radical~ or by fluorine, chlorine, bromine or lQ iodine;
-X- i~ a group -C~CH3)2-, ~C(CF3)2-, -CO-, -S~ , SO2 , -CH2-, -S- or ~O- or a direct bond and -Y- is a group SO2-, ~ C~, -CH2-, -O-, -S-, -C( CH3 ) Z~ ~ -t (CH 1)2~3C(CH9)2- -~ or -C(CF3) 2- or a direct bond.
According to the invention therefore, for the formation of the polyaramides contained in the membrane, one or more dicarboxylic acid derivatives of the formula ~I) and diamine component~ o the formula ~II) and, possibly, (III) are necessary, the ratio of the ~um of (II) and (III) to (I) being 0.90 to 1.10. Stoichiometric amounts of carboxylic acid derivati~es and diamine components are preferably u~ed.
To prepare the polysramide~ required according to the invention, the following compounds are ~uitable:
one or more dicarboxylic acid derivatives of ~he formula (I'~
Cl-C-A~-C-Cl (I') O O
for example terephthalyl dichloride and/or isophthalyl - 4 ~
dichloride, where the aroma~ic rincl i~ unsubstituted or is qubstituted by one or two branched or unbranched Cl-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radi-cals or Cl~C6-perfluoroalkyl or c1-CB-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine.
Aromatic diamines of the formula ~II'), H H
~~ ~D~ ~1 (II' for example 2,2'-bis[4-~4'~aminophenoxy)phenyl]propane, bis~3-(3~-aminophenoxy)phenyl] sulfone, bis[4-(4'-amino-phenoxy)phenyl] sulfone, bis[4-(4~-aminophenoxy)phenyl]-methane, 2,2'-bis[4-(4'-aminophenoxy)phenyl]hexafluoro propane and, possibly, aromatic diamines of the formula (III') ~2N ~ ~ ~2 (III') for example: bis[3-aminophenyl] sulfone, bis[4-amino-phenyl] sulfone, 1,4-bis[4'-aminophenoxy)benzene, bist4-aminophenyl)methane, bis[4,4'-aminophenyl) ether, bis[3,4'-aminophenyl) ether.
The ~olution condensation of aromatic dicarboxylic acid dichloride~ of the formulae (I') with aromatic diamines of the formulae (II') and, po sibly, (III') is carried out in aprotic polar solvents of the amide type, ~uch as for example in N,N-dimethylacetamide or in particular in N-methyl-2-pyrrolidone (NMP). If required, halide salts of the first and second subgroup of the Periodic Table of Elements can be added to these ~olvents in a known manner to increase the dissolving power or to stabilize the polyamide solution~. Preferred additives are calcium chloride and/or lithium chloride.
HOECHST AKTIENGESELLSCHAFT HOE 91/F 336 Dr. MI
Description Semipermeable, poxou , asymmetric polyether amide membranes Since the introduction of asymmetric membranes of cel-lulose acetate by Loeb and Sourixajan ~S. Sourixajan, Reverse Osmosis, Logos Press, London 1970) and of hydro-phobic polymers (~S Patent 3,615,024) a number of membrane have been developed and proposed, in particular for separation of low and high molecular constituent~
dissolved in water, the ~tructure and suitability of which are given in the literature (Desali~ation, 35 (1980), 5-20) and which have also been successfully tested in industrial practice or for clinical purposes.
Many of the membranes described have particularly advan-tageous properties for achieving specific tasks. As a result of their chemical constitution and their struc-ture, each individual membrane can be optimally suited only for quite ~pecific separation problems. From this results the fundamental requirement of continuously developing new membranes for new tasks.
EP-A 0 082 4~3 gives an overview of the advantages and di~advantages of membrane~ which are already known. Thus, for example, there are hydrophilic, asymmetric membranes of cellulose acetate having satisfactory antiadsorptive properties, but whose thermal and chemical stability leave a lot to be desired. Membranes of poly~ulfones or similar polymers do posse~s a good thermal and chemical stability, but such membranes, because of the hydrophobic properties of the polymer~ used, show a pronounced tendency to adsorb dissolved Rubsta~ces, as a result of which the membrane is blocked. The mixtures of polysulfone and polyvinylpyrrolidone di3closed in EP-A 0 082 433 do dispose of the disadvantage resulting from the hydrophobicity of the polysulfone, but these - 2 ~ t~
mixtures are sen3iti.ve to the action of organic solvent~.
Hydrophilicity and simultaneous resistance to solvents are found in membranes of regenerated cellulose; but these can be relatively easily hydrolyzed in acid or alkaline media/ and moreover they are easily attacked by microorganisms.
It is therefore an ob~ect of the invention to provide semipermeable, porous asymmetric membranes which are stable to chemical and thermal action, which can be prepared by a simple and economical method and wbose membrane properties can be easily varied according to the area of application.
This object is achieved by a semipermeable, porous, asymmetric membrane whose distinguishin~ features are that it contains a polyaramide which contains one or more of the recurring structural units of the formula (I) O O
¦¦ ll (I) -~-Ar-C-and, based on the sum of (II) and (III), up to 15 to 100 molar ~ of structural units of the formula (II) ~ u ~ ~ ~~ (II) and, based on the sum of (II) and (III), up to 0 to 85 molar % of structural units of the formula (III) -NH~ ~NH-( I I I ) where the ratio of the sum of (II) and (III) to (I) i5 0.90 to 1.10, but preferably 1~0 and the ~ymbols -AI-, -X- and -Y- have the following - 3 ~ p~.,~
meaning:
-Ar- i8 a divalent, aromatic or heteroaromatic radical, where the two ca.rbonyl gra,up~ are located on unad~acent ring carbon atom~ (.i.e. in para- or meta-position) and the Ar rsdical is un~ub~tituted or substituted by one or ~wo branched or unbranched C~-C3-alkyl or C~-C3-alkoxy radicals, aryl or aryloxy radical~ or Cl-C6 perfluoroalkyl or C~C6-perfluoro-alkoxy radical~ or by fluorine, chlorine, bromine or lQ iodine;
-X- i~ a group -C~CH3)2-, ~C(CF3)2-, -CO-, -S~ , SO2 , -CH2-, -S- or ~O- or a direct bond and -Y- is a group SO2-, ~ C~, -CH2-, -O-, -S-, -C( CH3 ) Z~ ~ -t (CH 1)2~3C(CH9)2- -~ or -C(CF3) 2- or a direct bond.
According to the invention therefore, for the formation of the polyaramides contained in the membrane, one or more dicarboxylic acid derivatives of the formula ~I) and diamine component~ o the formula ~II) and, possibly, (III) are necessary, the ratio of the ~um of (II) and (III) to (I) being 0.90 to 1.10. Stoichiometric amounts of carboxylic acid derivati~es and diamine components are preferably u~ed.
To prepare the polysramide~ required according to the invention, the following compounds are ~uitable:
one or more dicarboxylic acid derivatives of ~he formula (I'~
Cl-C-A~-C-Cl (I') O O
for example terephthalyl dichloride and/or isophthalyl - 4 ~
dichloride, where the aroma~ic rincl i~ unsubstituted or is qubstituted by one or two branched or unbranched Cl-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radi-cals or Cl~C6-perfluoroalkyl or c1-CB-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine.
Aromatic diamines of the formula ~II'), H H
~~ ~D~ ~1 (II' for example 2,2'-bis[4-~4'~aminophenoxy)phenyl]propane, bis~3-(3~-aminophenoxy)phenyl] sulfone, bis[4-(4'-amino-phenoxy)phenyl] sulfone, bis[4-(4~-aminophenoxy)phenyl]-methane, 2,2'-bis[4-(4'-aminophenoxy)phenyl]hexafluoro propane and, possibly, aromatic diamines of the formula (III') ~2N ~ ~ ~2 (III') for example: bis[3-aminophenyl] sulfone, bis[4-amino-phenyl] sulfone, 1,4-bis[4'-aminophenoxy)benzene, bist4-aminophenyl)methane, bis[4,4'-aminophenyl) ether, bis[3,4'-aminophenyl) ether.
The ~olution condensation of aromatic dicarboxylic acid dichloride~ of the formulae (I') with aromatic diamines of the formulae (II') and, po sibly, (III') is carried out in aprotic polar solvents of the amide type, ~uch as for example in N,N-dimethylacetamide or in particular in N-methyl-2-pyrrolidone (NMP). If required, halide salts of the first and second subgroup of the Periodic Table of Elements can be added to these ~olvents in a known manner to increase the dissolving power or to stabilize the polyamide solution~. Preferred additives are calcium chloride and/or lithium chloride.
- 5 ~
The polycondensation temperatures are conventionally between -20C and ~120C, preerably between +10C and +100C. Particularly good results are achieved at reac-tion temperatu~es between +10C ancl +80C. The polycon-densation reactions axe preferably carried out BO that after the reaction is completed, 3 to 50 % by weight, preferably 5 to 35 % by weight, of polycondensate is in the solution.
The polycondensation can be terminated in a conventional manner, for example by addition of monofunctional compounds, such as b~nzoyl chloride. After completion of the polycondensation, i.e. when the polymer 301ution has attained the Staudinger index required for further processing, the hydrogen chloride formed bound to the amide solvent is neutralized by addition of basic sub-stances. Suitable substances for this are for example lithium hydroxide, calcium hydroxide, in particular calcium oxide. After neutralization, the solutions are filtered and degassed and mem~ranes are drawn from these solutions. The concentration of the solutions and also the molecular weight of the polymers represent the most important production parameters, since by this means the mem~rane properties ~uch as porosity, mechanical stability, permeability and retention capacity may be adjusted.
The Staudinger index is a mea~ure for the mean chain length of the resulting polymers. The Staudinger index of the polyaramide is in the range from 50 to 1000 cm3/g~
preferably in the range from 100 to 500 cm3/g, particu-larly preferably in the range from 150 to 350 cm3/g. It was determined in solutions having 0.5 g of the particular polymer in 100 ml of 96% strength sulfuric acid at 25C.
The Staudinger index [~] (limiting viscosity, intrinsic viscosity) i8 taken to mean the expression - 6 ~ 3 lim P = [ ~7 ]
where C2 = concentration of the di3solved substance ~5p - sp~cif~c viscosity = -- --1 ~1 ~ = viscosity of the solution ~1 = viscosity of the pure solvent.
To produce the membrane according to the invention from polyaramides, the polyamide solution already described is filtered, degassed, and then, in a known manner using the phase inversion process (Robert E. Kesting, "Synthetic Polymeric Memhranes", 2nd Ed., 1985, p. 237 ff . ), an asymmetric porous membrane i~ produced. For thi~ purpose the polymer solution is spread as a liquid layer on a ~pport as flat a~ possible. The flat support can for example comprise a glass plate or a metal drum. A
precipitant liquid is then allowed to act on the liquid layer, which liquid is miscible with the solvent of the solution, but in which the polymers dissolved in the polymer solution are precipitated as a membrane.
Further suitable colvent constituent~ are readily volatile substance3 such as for example tetrahydrofuran, acetone or methylene chloride. Suitable prec~pitant liquids are water, mono- or polyhydricalcohols such as methanol~ ethanol, isopropanol, ethylene glycol or glycerol, or, additionally, mixtures of the~e sub~tanceQ
with each other or with aprotic, polar ~olvent~ such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, but in particular with N-methyl-2-pyrrolidone.
As a result of the action of the precipitant liquid on the liquid layer the polyaramides dissolved in the polymer solution are precipitated from thi~ solution with the formation of a porou~ film having an asymmetric pore - 7 ~. fn,~
structure.
The ~eparation efficiency and the rejection efficiency of the membranes according to the invention can be specifi-cally varied by addition of polyvinyl pyrrolidone (PVP) S to the solution of the polyaramide prior to the coagula-tion or by carrying out the polycondensation of the structural units (I), (II), and, possibly, (III) in the pre~ence of PVP or by a Rubsequent treatment at a temperature in the range of 60-140C, preferably in the range of 60-100C, with a liquid, for example with water, mixtures of water with mono- or polyhydricalcohol~ or also for example polyethylene glycol, or with polar, aprotic solvents of the amide type, ~uch as N-methyl-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide or mixtures of these liquids with each other or alter-natively by treatment with ~team, which may be superheated.
A thermal post-treatment of the membranes according to the invention leads to a compres ion of the active layer, 20 80 that a subsequent adju~tment of the rejection efficiency i5 possible in this manner.
As a result of the addition of polyvinylpyrrolidone to the polymer solution it is possible to achieve an increase in hydrophilicity and separation efficiency of the membranes according to the invention by preparation of a homogeneously miscible polymer blend and to achieve a better processability. The increa~ed hydrophilicity of the integrally asymmetric membrane leads to a reduced blockluging tendency, i.e. tc an expedient fouling behavior (lower decrea~e in ilux per unit of time and stabilization of the product flux at a hiyh level).
When there is an addition of polyvinylpyrrolidone, this is added in amounts of 1 to 80 ~ by weight, preferably 5 to 70 % by weight, particularly preferably 20 to 60 % by weight, relative to the ma~ of the polyamide.
~he molecular weight of the polyvinylpyrrolidone in thi~
~ ~ r, " "~ 3 f~
case is in the range from 10,000 to 2,000,000 dalton (g/mol) (given as weight average~, preferably in the range from 20,300 to 1,000,000, particularly preferably in the range from 30,000 to 95,000 dalton.
When the process i~ carried Ollt, the precipitant liquid is advantageously allowed to act on the membrane precipitated by this, until virtually all of the solvent in the membrane has been replaced by precipitant liquid.
The membrane formed is then freed from precipitant liquid, for example by drying the membrane directly in an air stream having a relativ~ humidity in thP range from 20 to 100 % or by fir~t treating it with a softener such as glycerol, or glycerol/water mixtures and then drying it.
To produce membranes which are arranged on a support layer, which is permeable to flowable media, the procedure as deRcribed above i~ carried out but the support used for forming the membrane layer iR a fabric or a nonwoven web, for example of plastic, for example polypropylene, polyethylene andtor polyethylene tere-phthalate, or of paper and after the membrane layer has been formed this is left on the support. However, the membrane can alternatively be first prepared without a support and only then applied to a permeable support.
Flat membranes produced in this manner have a thickness without support in the range from lO to 300 ~m, in particular in the range from 20 to 150 ~m. In a known manner (Mark C. Porter, "Handbook of Industrial Membrane Technology", 1990, p. 149ff), hollow fibers and capil-laries can alternatively be produced from the solution ofthe polyaramides, by spinning the polymer solution in accvrdance with the prior art through an appropriately designed shaping ring nozzle or hollow needle nozzle into a precipitant liquid. The wall thickness of such capil-laries or hollow fibers is conventionally in the rangefrom 20 to 500 ~m, in particular 80-200 ~m.
If the membrane is qoaked in glycerol after the coagulation, it can contain glycerol for example in the range from 5 to 60~, relative to its total weight;
membranes impregnated in this manner are dried, for example at a temperaOture of 50C.
The membrane according to the invention, apart from standard ~pplications of porou~ me~ranes known to those skilled in the art, such as pressure filtration (micro-l nano- and ultrafiltration), diafiltration and dialysis are likewise auitable as support m~mbranes for selec-tively permeable layers (for example for gas separation, pervaporation) which are produced directly on or in the membrane. Thus for example "ultrathin" layers (s 1 ~m) compo~ed of polymers having functional groups (for example silicones, cellulose ethers, fluorine copolymers) can be spread on water~ applied to the membrane surface from there and for example can be covalently fixed by reaction with a diisocyanate, in order to achieve more selective permeability by this means. Further methods for transfer of thin Yelectively permeable layers are known to those skilled in the art. By analogy, the membranes according to the invention are also suitable as supports for reactive molecules, for example to fix enzymes or anticoagulants such as heparin according to the prior art.
The thickness of the membranes according to the invention without support layer is in the range from 10 to 300 ~m, in particular from 20 to 120 ~m.
Examples:
Membranes of homo- and copolyaramide~
For the membranes studied in the examples, the corre-sponding polyaramides were prepared as described above in N-methylpyrrolidone (NMP) as solvent by a polycon-denqation at 50C.
A solution of this polyaramide was applied to a nonwoven support web of polypropylene and was coagulated in water at 20~C.
The permeate flux of an ultrafiltration membrane produced -- 10 ~ " r ~ ; f~
in this manner ~nd the rejection eff:iciency for dissolved macromolecules were determined at pressures of 3.0 bar at 20C in a stirred cylindrical cel.l (500 rpm/ 250 ml, membrane surface area 38 cm2)~
5 The rejection efficiency is by defi:nition C~- C2 R = ~ 100 ~
Cl is the concentration sf the aqueous test solution, C2 is the concentration in the permeate.
Example 1: ~ 9S molar ~ of terephthalyl dichloride (TPC) 100 molar % of 2,2'-bis[4-(4' amino-phenoxy)phenyl]propane (BAP) 15 Example 2: ~ 95 molar ~ of TPC
100 molar % of bi [4-(4'-aminophenoxy)-phenyl] sulfone (BAPS) Example 3: 2 95 molar % of isophthalyl dichloride (IPC~
100 molar % of BAP
Example 4: 2 95 molar % of (O.8 TPC + O.2 IPC) 100 molar ~ of BAP
Example 5: > 95 molar ~ of TPC
70 molar % of BAP + 30 molar ~ of bis(4-aminophenyl) sulfone Test substances for the rejection determination and additives used:
The test solutions used were aqueou~ polyvinylpyrrolidone solutions and aqueous solutions of fractionated dextrans.
The density measurementR were carried out using a density measuring apparatus ~DA 210 from the Kyoto ~lectronics company.
K 30. polyvinylpyrrolidone (M~ 43,000) (~LIviskol 2 % strength aqueous solution K30, ~A5lF), T 10: dextran ~MW lO,000) (~Dextran T10, 1 % strength aqueGus ~olution Ph2~nhcia), Dextran (qDextran blue, blue: dextran with dye labeling Pharnacia), (MW 2,000,000) 0.5 ~ strength aquecus solution K 90: poly~inylpyrrolidone (~W 1,200,000~ uviskol KgO, E~SF) Aerosil.pyrogenic silica gel (Aerosil 200, Degus~a) -H ~! _ ,~ o n ~ E~
c~ l~c~
~ ~ ~ 0 ~n .~ ~ XI ~ ~ ~ r~
. . _. O-- -- ~ ~1 H ;op ~ -- E ~ _ .~
~ ~ _ ~ ~ o o ~ a) ~ - æ ~ I o~ ~ ~
o ~ ~c ~7 ~ ~ 8 ~ ~ ~I ~ n ~ ~ ~ ` ,~
~ ~ ~ a o oo ~co ~ ~
~ _ ~ ~ ~
t ~ '.~ _ .
~ ~dP ~1~ ~- +
~ ~ -- N ~ .
- 13 ~
u~ing homopolyaramide3 of TPC and }3~P, membranes can be produced in a very hroad concentration range. If the viscosity i~ adjusted ~o [~] - 110 ml/g, all membranes having a polyme.r concentration greater than 20 ~ are not permeable to water and aqueous solutions up to 40 bar. As the polymer concentration falls, ~he permeability to water very sharply increa~es. The rejection values of the test substances K30 and T10 behave inversely. While the rejection of ~30 only decrea3es gradually because of the broad molecular weight di~tribution of the polyvinyl-pyrrolidone, the rejection of dextran T10 (narrow molecular weight di~trlbution) decreases very rapidly to values which can no longer be measured.
- - - - - ~
E ~ CO N tO l U~
, ~tl __ r--~ ~ CO ~D ~ l O~
:~~ _ _ ~P U~ C~ Lt~
~ ~ o~ ~ l l .~ O O O
~ _I ~1 N N ~) l C~ .~
~O _ _ , _ ;~
~q ~o oO n COD O
.~ ~-- .
~ ~.~."
Q) ~ ~ O O O O
~2 p~ o _l u) o ~
~ ~ ~ _ _ -'t N 1~ ~ ~ _ --I 2 1~
- 15 - ~3t,.,~
From the preceding table it can be seen that PVP-containing membranes, compared to PVP-free membrane~, have an increaLsed ~ater flux, ~ith approximately equal reject.ion effi.ciencies (see C2 = 17.5 ~ and PVP addition S O and 50 %). In addition it can be seen that a membrane produced from a 20 % strength polymer solution which i~
not permeable to water is made permleable by PVP addition.
, ` ?~
' _ - I _ _ _ , 1~ 1~ ~o ~ In I~ ~ U~ C~ O
_ ~ er I_ r- r~ ~o .~
.~ o rl n~ d~ ~ r~ e~' O ~ ~0 æ~ ~ QO ~ CD ~ ~ O~
_ _ Ul $ O O O
_ ~ U~ _, _, ~ ~ _, ~.~ ~_. ~
~ _, O~ ~, 0 U~ ~
~'' . _ ' .
;~ ~ O l o ~ o ~ ~
H ~ . . g .~ _~ ~
~ a o o .~ D
`; '3 A polyaramide membran~ (from a 17 5% strength solution without PVP) i5 heated for 10 minute~ at 100C in water.
As a result of this treatment, analogous to a sintering process, the membrane covering layer compresses and the rejection value increases. While the K30 rejection is already quantitative from a heating temperature of 80C
(not given in the table), the T 10 rejection increases from approximately 80% ~o 97%. A thermal treatment of this aramide membrane allows an individual membrane to be adjusted so that it can find an application in the ultrafiltration region and in the neighboring nano-filtration region.
If a thermal post-treatment is given to PVP-containing membranes, analogously to the case without PVP addition, a compression of th~ membrane covering layer results with increase of the rejection ~alues for the test substances.
Analogously to Table 1.2, higher permeabilities are also shown here with PVP-containing membranes in comparison to their PVP-free variants.
A 50% PVP addition and heating for 10 minutes at 100C
gives a membrane having 96~ rejection for T10 and a water ~flux of 80 l~m2h. The comparable membrane without PVP, at an approximately equal rejection of 97~, ha~ a water flux of only 55 l/m2h.
,.
- 18 - 2 ``J ';"' ' -1.4) Polyaramide hollow fiber membrane Internal diameter - 102 mm Stream flow rate 3-4 m/s, t:ransmem~rane pressure 3.5 bar C2 = lS~ in NMP
Th~E1 M~*~ane Water Rejection Permeate treatment layer flux [~] flux [mln/~C] t[h~m]kne5S [l/~h] K 30 [l/~h]
_ ____ _ _ 250 40 76 20 e _ A polyaramide hollow fiber is individually stretched between two needles and is tested with the aid of a pump and an externally applied pressure using the crossflow technique. The pxessure is measured at the inlet and 20 outlet of the hollow fiber and the transmembrane pressure (TMP) is determined therefrom [TMP = ~PE + PA/)2]
PE = inlet pressure PA = outlet pressure -- 1 9 '~ J ~ 3 _ o_ _ _ .
~o ~ t~ o o t o ~ ~ -- U~ ~7 ~ O
__ ~ ~
~ _. t t~, t~ .~ ~
~ ~ ................................. ~ ~
~ ~ ~ ~ ~ ~ ~ ~ ~n ,~UO~ .~ ~ ~ ~ ~ ~ ~ ~.~
~ 11 ~ dP dl dP ~ dP dP ~ ~
l ~ ~ ~ ~1 _i ~ Ln, U~ ~ ~ ~
t ~ ~ ~ .,~
~ _5 ~ _, _, "~
.r3 -_ ~ ~ r ~t_ _ .
.~o o~ ~ o~
,. . ~ _ _ _ . ~ ~
~o o o ,o o o o ~ g _ _ __ ~a ~.~ .
@ ~ ~ ~ ~ ~o ~o o~ ~o ~ ~o o ~o ~ ~
_ ~ .- .~ .
~ .~ O O 0~ O i~ ~æ
~ ~ ~ l c~; P~ l P~ x ;n n K
b _ ~ ~ ~
Q ._ a~ _ ~D
e .~ ~ ~
~ ~O N
l~ ~
~ If~ .
9 ~ , 9 3 ~c ~ . 9
The polycondensation temperatures are conventionally between -20C and ~120C, preerably between +10C and +100C. Particularly good results are achieved at reac-tion temperatu~es between +10C ancl +80C. The polycon-densation reactions axe preferably carried out BO that after the reaction is completed, 3 to 50 % by weight, preferably 5 to 35 % by weight, of polycondensate is in the solution.
The polycondensation can be terminated in a conventional manner, for example by addition of monofunctional compounds, such as b~nzoyl chloride. After completion of the polycondensation, i.e. when the polymer 301ution has attained the Staudinger index required for further processing, the hydrogen chloride formed bound to the amide solvent is neutralized by addition of basic sub-stances. Suitable substances for this are for example lithium hydroxide, calcium hydroxide, in particular calcium oxide. After neutralization, the solutions are filtered and degassed and mem~ranes are drawn from these solutions. The concentration of the solutions and also the molecular weight of the polymers represent the most important production parameters, since by this means the mem~rane properties ~uch as porosity, mechanical stability, permeability and retention capacity may be adjusted.
The Staudinger index is a mea~ure for the mean chain length of the resulting polymers. The Staudinger index of the polyaramide is in the range from 50 to 1000 cm3/g~
preferably in the range from 100 to 500 cm3/g, particu-larly preferably in the range from 150 to 350 cm3/g. It was determined in solutions having 0.5 g of the particular polymer in 100 ml of 96% strength sulfuric acid at 25C.
The Staudinger index [~] (limiting viscosity, intrinsic viscosity) i8 taken to mean the expression - 6 ~ 3 lim P = [ ~7 ]
where C2 = concentration of the di3solved substance ~5p - sp~cif~c viscosity = -- --1 ~1 ~ = viscosity of the solution ~1 = viscosity of the pure solvent.
To produce the membrane according to the invention from polyaramides, the polyamide solution already described is filtered, degassed, and then, in a known manner using the phase inversion process (Robert E. Kesting, "Synthetic Polymeric Memhranes", 2nd Ed., 1985, p. 237 ff . ), an asymmetric porous membrane i~ produced. For thi~ purpose the polymer solution is spread as a liquid layer on a ~pport as flat a~ possible. The flat support can for example comprise a glass plate or a metal drum. A
precipitant liquid is then allowed to act on the liquid layer, which liquid is miscible with the solvent of the solution, but in which the polymers dissolved in the polymer solution are precipitated as a membrane.
Further suitable colvent constituent~ are readily volatile substance3 such as for example tetrahydrofuran, acetone or methylene chloride. Suitable prec~pitant liquids are water, mono- or polyhydricalcohols such as methanol~ ethanol, isopropanol, ethylene glycol or glycerol, or, additionally, mixtures of the~e sub~tanceQ
with each other or with aprotic, polar ~olvent~ such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, but in particular with N-methyl-2-pyrrolidone.
As a result of the action of the precipitant liquid on the liquid layer the polyaramides dissolved in the polymer solution are precipitated from thi~ solution with the formation of a porou~ film having an asymmetric pore - 7 ~. fn,~
structure.
The ~eparation efficiency and the rejection efficiency of the membranes according to the invention can be specifi-cally varied by addition of polyvinyl pyrrolidone (PVP) S to the solution of the polyaramide prior to the coagula-tion or by carrying out the polycondensation of the structural units (I), (II), and, possibly, (III) in the pre~ence of PVP or by a Rubsequent treatment at a temperature in the range of 60-140C, preferably in the range of 60-100C, with a liquid, for example with water, mixtures of water with mono- or polyhydricalcohol~ or also for example polyethylene glycol, or with polar, aprotic solvents of the amide type, ~uch as N-methyl-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide or mixtures of these liquids with each other or alter-natively by treatment with ~team, which may be superheated.
A thermal post-treatment of the membranes according to the invention leads to a compres ion of the active layer, 20 80 that a subsequent adju~tment of the rejection efficiency i5 possible in this manner.
As a result of the addition of polyvinylpyrrolidone to the polymer solution it is possible to achieve an increase in hydrophilicity and separation efficiency of the membranes according to the invention by preparation of a homogeneously miscible polymer blend and to achieve a better processability. The increa~ed hydrophilicity of the integrally asymmetric membrane leads to a reduced blockluging tendency, i.e. tc an expedient fouling behavior (lower decrea~e in ilux per unit of time and stabilization of the product flux at a hiyh level).
When there is an addition of polyvinylpyrrolidone, this is added in amounts of 1 to 80 ~ by weight, preferably 5 to 70 % by weight, particularly preferably 20 to 60 % by weight, relative to the ma~ of the polyamide.
~he molecular weight of the polyvinylpyrrolidone in thi~
~ ~ r, " "~ 3 f~
case is in the range from 10,000 to 2,000,000 dalton (g/mol) (given as weight average~, preferably in the range from 20,300 to 1,000,000, particularly preferably in the range from 30,000 to 95,000 dalton.
When the process i~ carried Ollt, the precipitant liquid is advantageously allowed to act on the membrane precipitated by this, until virtually all of the solvent in the membrane has been replaced by precipitant liquid.
The membrane formed is then freed from precipitant liquid, for example by drying the membrane directly in an air stream having a relativ~ humidity in thP range from 20 to 100 % or by fir~t treating it with a softener such as glycerol, or glycerol/water mixtures and then drying it.
To produce membranes which are arranged on a support layer, which is permeable to flowable media, the procedure as deRcribed above i~ carried out but the support used for forming the membrane layer iR a fabric or a nonwoven web, for example of plastic, for example polypropylene, polyethylene andtor polyethylene tere-phthalate, or of paper and after the membrane layer has been formed this is left on the support. However, the membrane can alternatively be first prepared without a support and only then applied to a permeable support.
Flat membranes produced in this manner have a thickness without support in the range from lO to 300 ~m, in particular in the range from 20 to 150 ~m. In a known manner (Mark C. Porter, "Handbook of Industrial Membrane Technology", 1990, p. 149ff), hollow fibers and capil-laries can alternatively be produced from the solution ofthe polyaramides, by spinning the polymer solution in accvrdance with the prior art through an appropriately designed shaping ring nozzle or hollow needle nozzle into a precipitant liquid. The wall thickness of such capil-laries or hollow fibers is conventionally in the rangefrom 20 to 500 ~m, in particular 80-200 ~m.
If the membrane is qoaked in glycerol after the coagulation, it can contain glycerol for example in the range from 5 to 60~, relative to its total weight;
membranes impregnated in this manner are dried, for example at a temperaOture of 50C.
The membrane according to the invention, apart from standard ~pplications of porou~ me~ranes known to those skilled in the art, such as pressure filtration (micro-l nano- and ultrafiltration), diafiltration and dialysis are likewise auitable as support m~mbranes for selec-tively permeable layers (for example for gas separation, pervaporation) which are produced directly on or in the membrane. Thus for example "ultrathin" layers (s 1 ~m) compo~ed of polymers having functional groups (for example silicones, cellulose ethers, fluorine copolymers) can be spread on water~ applied to the membrane surface from there and for example can be covalently fixed by reaction with a diisocyanate, in order to achieve more selective permeability by this means. Further methods for transfer of thin Yelectively permeable layers are known to those skilled in the art. By analogy, the membranes according to the invention are also suitable as supports for reactive molecules, for example to fix enzymes or anticoagulants such as heparin according to the prior art.
The thickness of the membranes according to the invention without support layer is in the range from 10 to 300 ~m, in particular from 20 to 120 ~m.
Examples:
Membranes of homo- and copolyaramide~
For the membranes studied in the examples, the corre-sponding polyaramides were prepared as described above in N-methylpyrrolidone (NMP) as solvent by a polycon-denqation at 50C.
A solution of this polyaramide was applied to a nonwoven support web of polypropylene and was coagulated in water at 20~C.
The permeate flux of an ultrafiltration membrane produced -- 10 ~ " r ~ ; f~
in this manner ~nd the rejection eff:iciency for dissolved macromolecules were determined at pressures of 3.0 bar at 20C in a stirred cylindrical cel.l (500 rpm/ 250 ml, membrane surface area 38 cm2)~
5 The rejection efficiency is by defi:nition C~- C2 R = ~ 100 ~
Cl is the concentration sf the aqueous test solution, C2 is the concentration in the permeate.
Example 1: ~ 9S molar ~ of terephthalyl dichloride (TPC) 100 molar % of 2,2'-bis[4-(4' amino-phenoxy)phenyl]propane (BAP) 15 Example 2: ~ 95 molar ~ of TPC
100 molar % of bi [4-(4'-aminophenoxy)-phenyl] sulfone (BAPS) Example 3: 2 95 molar % of isophthalyl dichloride (IPC~
100 molar % of BAP
Example 4: 2 95 molar % of (O.8 TPC + O.2 IPC) 100 molar ~ of BAP
Example 5: > 95 molar ~ of TPC
70 molar % of BAP + 30 molar ~ of bis(4-aminophenyl) sulfone Test substances for the rejection determination and additives used:
The test solutions used were aqueou~ polyvinylpyrrolidone solutions and aqueous solutions of fractionated dextrans.
The density measurementR were carried out using a density measuring apparatus ~DA 210 from the Kyoto ~lectronics company.
K 30. polyvinylpyrrolidone (M~ 43,000) (~LIviskol 2 % strength aqueous solution K30, ~A5lF), T 10: dextran ~MW lO,000) (~Dextran T10, 1 % strength aqueGus ~olution Ph2~nhcia), Dextran (qDextran blue, blue: dextran with dye labeling Pharnacia), (MW 2,000,000) 0.5 ~ strength aquecus solution K 90: poly~inylpyrrolidone (~W 1,200,000~ uviskol KgO, E~SF) Aerosil.pyrogenic silica gel (Aerosil 200, Degus~a) -H ~! _ ,~ o n ~ E~
c~ l~c~
~ ~ ~ 0 ~n .~ ~ XI ~ ~ ~ r~
. . _. O-- -- ~ ~1 H ;op ~ -- E ~ _ .~
~ ~ _ ~ ~ o o ~ a) ~ - æ ~ I o~ ~ ~
o ~ ~c ~7 ~ ~ 8 ~ ~ ~I ~ n ~ ~ ~ ` ,~
~ ~ ~ a o oo ~co ~ ~
~ _ ~ ~ ~
t ~ '.~ _ .
~ ~dP ~1~ ~- +
~ ~ -- N ~ .
- 13 ~
u~ing homopolyaramide3 of TPC and }3~P, membranes can be produced in a very hroad concentration range. If the viscosity i~ adjusted ~o [~] - 110 ml/g, all membranes having a polyme.r concentration greater than 20 ~ are not permeable to water and aqueous solutions up to 40 bar. As the polymer concentration falls, ~he permeability to water very sharply increa~es. The rejection values of the test substances K30 and T10 behave inversely. While the rejection of ~30 only decrea3es gradually because of the broad molecular weight di~tribution of the polyvinyl-pyrrolidone, the rejection of dextran T10 (narrow molecular weight di~trlbution) decreases very rapidly to values which can no longer be measured.
- - - - - ~
E ~ CO N tO l U~
, ~tl __ r--~ ~ CO ~D ~ l O~
:~~ _ _ ~P U~ C~ Lt~
~ ~ o~ ~ l l .~ O O O
~ _I ~1 N N ~) l C~ .~
~O _ _ , _ ;~
~q ~o oO n COD O
.~ ~-- .
~ ~.~."
Q) ~ ~ O O O O
~2 p~ o _l u) o ~
~ ~ ~ _ _ -'t N 1~ ~ ~ _ --I 2 1~
- 15 - ~3t,.,~
From the preceding table it can be seen that PVP-containing membranes, compared to PVP-free membrane~, have an increaLsed ~ater flux, ~ith approximately equal reject.ion effi.ciencies (see C2 = 17.5 ~ and PVP addition S O and 50 %). In addition it can be seen that a membrane produced from a 20 % strength polymer solution which i~
not permeable to water is made permleable by PVP addition.
, ` ?~
' _ - I _ _ _ , 1~ 1~ ~o ~ In I~ ~ U~ C~ O
_ ~ er I_ r- r~ ~o .~
.~ o rl n~ d~ ~ r~ e~' O ~ ~0 æ~ ~ QO ~ CD ~ ~ O~
_ _ Ul $ O O O
_ ~ U~ _, _, ~ ~ _, ~.~ ~_. ~
~ _, O~ ~, 0 U~ ~
~'' . _ ' .
;~ ~ O l o ~ o ~ ~
H ~ . . g .~ _~ ~
~ a o o .~ D
`; '3 A polyaramide membran~ (from a 17 5% strength solution without PVP) i5 heated for 10 minute~ at 100C in water.
As a result of this treatment, analogous to a sintering process, the membrane covering layer compresses and the rejection value increases. While the K30 rejection is already quantitative from a heating temperature of 80C
(not given in the table), the T 10 rejection increases from approximately 80% ~o 97%. A thermal treatment of this aramide membrane allows an individual membrane to be adjusted so that it can find an application in the ultrafiltration region and in the neighboring nano-filtration region.
If a thermal post-treatment is given to PVP-containing membranes, analogously to the case without PVP addition, a compression of th~ membrane covering layer results with increase of the rejection ~alues for the test substances.
Analogously to Table 1.2, higher permeabilities are also shown here with PVP-containing membranes in comparison to their PVP-free variants.
A 50% PVP addition and heating for 10 minutes at 100C
gives a membrane having 96~ rejection for T10 and a water ~flux of 80 l~m2h. The comparable membrane without PVP, at an approximately equal rejection of 97~, ha~ a water flux of only 55 l/m2h.
,.
- 18 - 2 ``J ';"' ' -1.4) Polyaramide hollow fiber membrane Internal diameter - 102 mm Stream flow rate 3-4 m/s, t:ransmem~rane pressure 3.5 bar C2 = lS~ in NMP
Th~E1 M~*~ane Water Rejection Permeate treatment layer flux [~] flux [mln/~C] t[h~m]kne5S [l/~h] K 30 [l/~h]
_ ____ _ _ 250 40 76 20 e _ A polyaramide hollow fiber is individually stretched between two needles and is tested with the aid of a pump and an externally applied pressure using the crossflow technique. The pxessure is measured at the inlet and 20 outlet of the hollow fiber and the transmembrane pressure (TMP) is determined therefrom [TMP = ~PE + PA/)2]
PE = inlet pressure PA = outlet pressure -- 1 9 '~ J ~ 3 _ o_ _ _ .
~o ~ t~ o o t o ~ ~ -- U~ ~7 ~ O
__ ~ ~
~ _. t t~, t~ .~ ~
~ ~ ................................. ~ ~
~ ~ ~ ~ ~ ~ ~ ~ ~n ,~UO~ .~ ~ ~ ~ ~ ~ ~ ~.~
~ 11 ~ dP dl dP ~ dP dP ~ ~
l ~ ~ ~ ~1 _i ~ Ln, U~ ~ ~ ~
t ~ ~ ~ .,~
~ _5 ~ _, _, "~
.r3 -_ ~ ~ r ~t_ _ .
.~o o~ ~ o~
,. . ~ _ _ _ . ~ ~
~o o o ,o o o o ~ g _ _ __ ~a ~.~ .
@ ~ ~ ~ ~ ~o ~o o~ ~o ~ ~o o ~o ~ ~
_ ~ .- .~ .
~ .~ O O 0~ O i~ ~æ
~ ~ ~ l c~; P~ l P~ x ;n n K
b _ ~ ~ ~
Q ._ a~ _ ~D
e .~ ~ ~
~ ~O N
l~ ~
~ If~ .
9 ~ , 9 3 ~c ~ . 9
Claims (15)
1. A semipermeable, porous, asymmetric membrane, which contain a polyaramide which contains one or more of the recurring structural units of the formula (I) (I) and, based on the sum of (II) and (III), up to 15 to 100 molar % of structural units of the formula (II) (II) and, based on the sum of (II) and (III), up to 0 to 85 molar % of structural units of the formula (III) (III) where the ratio of the sum of (II) and (III) to (I) is 0.90 to 1.10, and the symbols -Ar-, -X- and -Y-have the following meaning:
-Ar- is a divalent, aromatic or heteroaromatic radical, where the two carbonyl groups of the Ar radical are located on unadjacent ring carbon atoms (i.e. in para- or meta-position) and the Ar radical is unsubstituted or substituted by one or two branched or unbranched C1-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radicals or C1-C6-perfluoroalkyl or C1-C6-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine;
-X- is a group -C(CH3)2-, -C(CF3)2-, -CO-, -SO-, -SO2-, -CH2-, -S- or -O- or a direct bond and -Y- is a group -SO2-, , -CH2-, -O-, -C(CH3)2-, , or -C(CF3)2- or a direct bond.
-Ar- is a divalent, aromatic or heteroaromatic radical, where the two carbonyl groups of the Ar radical are located on unadjacent ring carbon atoms (i.e. in para- or meta-position) and the Ar radical is unsubstituted or substituted by one or two branched or unbranched C1-C3-alkyl or C1-C3-alkoxy radicals, aryl or aryloxy radicals or C1-C6-perfluoroalkyl or C1-C6-perfluoroalkoxy radicals or by fluorine, chlorine, bromine or iodine;
-X- is a group -C(CH3)2-, -C(CF3)2-, -CO-, -SO-, -SO2-, -CH2-, -S- or -O- or a direct bond and -Y- is a group -SO2-, , -CH2-, -O-, -C(CH3)2-, , or -C(CF3)2- or a direct bond.
2. The semipermeable, porous, asymmetric membrane as claimed in claim 1, wherein the polyaramide has a Staudinger index in the range 50 to 1,000 cm3/g, preferably 100 to 500 cm3/g.
3. The membrane as claimed in claim 1, wherein it is a flat membrane having a thickness in the range 10 to 300 µm.
4. The membrane as claimed in claim 1, wherein it is arranged on a support layer, permeable to flowable media, composed of plastic nonwoven web or on a fabric.
5. The membrane as claimed in claim 4, wherein the plastic nonwoven web contains polyethylene terephthalate or polypropylene.
6. The membrane as claimed in claim 4, wherein it is a hollow fiber membrane.
7. A process for the production of a membrane as claimed in claim 1, in which the polymer solution is spread as a liquid layer on a flat support and then a precipitant liquid is applied to the liquid layer, which precipitant liquid is miscible with the solvent of the solution, but in which the polymers dissolved in the polymer solution are precipitated as a membrane, wherein the solvents for the polyaramides contain aprotic polar solvents of the amide type such as N-dimethylacetamide or in particular N-methyl-2-pyrrolidone as the major constituent and the polymer solution has a concentration in the range from 3 to 50 % by weight, preferably 5 to 35 % by weight.
8. The process a claimed in claim 7, wherein readily volatile substances such as tetrahydrofuran, acetone or methylene chloride are used as further constituents of the solvent.
9. The process as claimed in claim 7, wherein alcohols such as methanol, ethanol, isopropanol, ethylene glycol or glycerol are used as the precipitant liquid.
10. A process for changing the rejection efficiency of a membrane, which comprises subjecting the membrane, in which virtually all the solvent has been replaced by precipitant liquid, to a heat treatment in a liquid.
11. The process as claimed in claim 10, wherein the liquid is water, a mono- or polyhhydricalcohol or a polar aprotic solvent of the amide type or a mixture of these liquids and the heat treatment is carried out at temperatures in the range from 60 to 140°C.
12. A process for changing the separation efficiency of a membrane as claimed in claim 1, which comprises adding polyvinylpyrrolidone to the polyaramide solution.
13. The process as claimed in claim 12, wherein the polycondensation of structural units of the formulae (I), (II) and, possibly, (III) is carried out in the presence of polyvinylpyrrolidone.
14. The process as claimed in claim 13, wherein the polyaramide solution contains polyvinylpyrrolidone having a molecular weight, reported as weight average, in the range from 10,000 to 2,000,000, preferably 20,000 to 1,000,000.
15. The process as claimed in claim 12, wherein the polymer solution contains polyvinylpyrrolidone at 1 to 80 % by weight, preferably at 5 to 70 % by weight, based on the polyaramide fraction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4135341.2 | 1991-10-26 | ||
| DE4135341 | 1991-10-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2081260A1 true CA2081260A1 (en) | 1993-04-27 |
Family
ID=6443472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002081260A Abandoned CA2081260A1 (en) | 1991-10-26 | 1992-10-23 | Semipermeable, porous, asymmetric polyether amide membranes |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0543171B1 (en) |
| JP (1) | JPH05208123A (en) |
| KR (1) | KR930007496A (en) |
| CA (1) | CA2081260A1 (en) |
| DE (1) | DE59208013D1 (en) |
| DK (1) | DK0543171T3 (en) |
| IL (1) | IL103525A0 (en) |
| TW (1) | TW224109B (en) |
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| US5266100A (en) * | 1992-09-02 | 1993-11-30 | E. I. Du Pont De Nemours And Company | Alkyl substituted polyimide, polyamide and polyamide-imide gas separation membranes |
| EP0604883A3 (en) | 1992-12-30 | 1995-02-15 | Hoechst Ag | Process for preparing porous hydrophilic membranes. |
| DE4418843A1 (en) | 1994-05-30 | 1995-12-07 | Hoechst Ag | Porous membrane made from aromatic polyamide |
| DE19549001A1 (en) | 1995-12-28 | 1997-07-03 | Hoechst Ag | Process for the preparation of polyether amide solutions, steam-sterilizable dialysis membranes obtainable using the polyether amide solutions, and process for the production of these membranes |
| IL143066A0 (en) * | 1998-11-13 | 2002-04-21 | Akzo Nobel Nv | Pervaporation device and irrigation mat |
| US20070227966A1 (en) * | 2006-03-31 | 2007-10-04 | Koo Ja-Young | Composite polyamide reverse osmosis membrane showing high boron rejection and method of producing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4217227A (en) * | 1975-12-06 | 1980-08-12 | Bayer Aktiengesellschaft | Semipermeable membranes of copolyamides |
| JPS5670805A (en) * | 1979-11-15 | 1981-06-13 | Nitto Electric Ind Co Ltd | Preparation of selectively permeable membrane for treating organic liquid |
| CA1202837A (en) * | 1980-03-14 | 1986-04-08 | Wolfgang J. Wrasidlo | Asymmetric membranes and process therefor |
| ES516206A0 (en) * | 1981-10-21 | 1983-10-01 | Du Pont | "IMPROVEMENTS INTRODUCED IN A PROCEDURE FOR THE PREPARATION OF A REVERSE OSMOSIS MEMBRANE". |
| DE3342823A1 (en) * | 1983-11-26 | 1985-06-05 | Seitz-Filter-Werke Theo & Geo Seitz GmbH und Co, 6550 Bad Kreuznach | METHOD FOR PRODUCING FILTER ELEMENTS BASED ON AROMATIC POLYAMIDE |
| DE3856346D1 (en) * | 1987-05-06 | 1999-08-05 | Usf Filtration & Separations | MANUFACTURE OF POROUS ARAMID MEMBRANES |
| JPH01231903A (en) * | 1988-03-14 | 1989-09-18 | Nippon Steel Corp | Hollow yarn separating membrane and its production |
| JP2701357B2 (en) * | 1988-08-30 | 1998-01-21 | 東洋紡績株式会社 | Casting dope for film formation |
| DE3903098A1 (en) * | 1989-02-02 | 1990-08-16 | Hoechst Ag | SEMIPERMEABLE MEMBRANE MADE OF A HOMOGENOUSLY MIXABLE POLYMER ALLOY |
| US5085676A (en) * | 1990-12-04 | 1992-02-04 | E. I. Du Pont De Nemours And Company | Novel multicomponent fluid separation membranes |
| TW205513B (en) * | 1991-02-28 | 1993-05-11 | Hoechst Ag |
-
1992
- 1992-10-22 DE DE59208013T patent/DE59208013D1/en not_active Expired - Fee Related
- 1992-10-22 DK DK92118115.2T patent/DK0543171T3/en active
- 1992-10-22 EP EP92118115A patent/EP0543171B1/en not_active Expired - Lifetime
- 1992-10-23 IL IL103525A patent/IL103525A0/en unknown
- 1992-10-23 CA CA002081260A patent/CA2081260A1/en not_active Abandoned
- 1992-10-26 KR KR1019920019719A patent/KR930007496A/en not_active Application Discontinuation
- 1992-10-26 JP JP4287871A patent/JPH05208123A/en active Pending
- 1992-10-28 TW TW081108573A patent/TW224109B/zh active
Also Published As
| Publication number | Publication date |
|---|---|
| TW224109B (en) | 1994-05-21 |
| KR930007496A (en) | 1993-05-20 |
| DK0543171T3 (en) | 1997-07-28 |
| EP0543171A1 (en) | 1993-05-26 |
| EP0543171B1 (en) | 1997-02-05 |
| DE59208013D1 (en) | 1997-03-20 |
| JPH05208123A (en) | 1993-08-20 |
| IL103525A0 (en) | 1993-03-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |