GB2086798A - Microporous cellulose membrane - Google Patents
Microporous cellulose membrane Download PDFInfo
- Publication number
- GB2086798A GB2086798A GB8133372A GB8133372A GB2086798A GB 2086798 A GB2086798 A GB 2086798A GB 8133372 A GB8133372 A GB 8133372A GB 8133372 A GB8133372 A GB 8133372A GB 2086798 A GB2086798 A GB 2086798A
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- cellulose
- weight
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- solution
- coagulation bath
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- 239000012528 membrane Substances 0.000 title claims abstract description 58
- 229920002678 cellulose Polymers 0.000 title claims abstract description 38
- 239000001913 cellulose Substances 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 33
- 230000008569 process Effects 0.000 claims abstract description 29
- 238000005345 coagulation Methods 0.000 claims abstract description 27
- 230000015271 coagulation Effects 0.000 claims abstract description 27
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000009987 spinning Methods 0.000 claims abstract description 18
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 17
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 16
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 16
- 239000011148 porous material Substances 0.000 claims abstract description 12
- 239000010949 copper Substances 0.000 claims abstract description 11
- 239000012982 microporous membrane Substances 0.000 claims abstract description 9
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 230000007717 exclusion Effects 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims abstract description 3
- 150000001879 copper Chemical class 0.000 claims abstract description 3
- 238000001471 micro-filtration Methods 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 9
- 235000011149 sulphuric acid Nutrition 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 6
- 239000001117 sulphuric acid Substances 0.000 claims description 5
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims 1
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 42
- 108010088751 Albumins Proteins 0.000 description 8
- 102000009027 Albumins Human genes 0.000 description 8
- 239000000126 substance Substances 0.000 description 7
- 230000035699 permeability Effects 0.000 description 6
- 235000018102 proteins Nutrition 0.000 description 6
- 102000004169 proteins and genes Human genes 0.000 description 6
- 108090000623 proteins and genes Proteins 0.000 description 6
- 238000012216 screening Methods 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 210000004369 blood Anatomy 0.000 description 5
- 239000008280 blood Substances 0.000 description 5
- 229920002301 cellulose acetate Polymers 0.000 description 5
- 239000010408 film Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 4
- 239000000470 constituent Substances 0.000 description 4
- 238000000502 dialysis Methods 0.000 description 4
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 4
- 210000002381 plasma Anatomy 0.000 description 4
- 229920003023 plastic Polymers 0.000 description 4
- 239000004033 plastic Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000002615 hemofiltration Methods 0.000 description 3
- 239000004627 regenerated cellulose Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 150000002191 fatty alcohols Chemical class 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000001631 haemodialysis Methods 0.000 description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- -1 nonyl phenyl Chemical group 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000002504 physiological saline solution Substances 0.000 description 2
- 229920001451 polypropylene glycol Polymers 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000003053 toxin Substances 0.000 description 2
- 231100000765 toxin Toxicity 0.000 description 2
- 108700012359 toxins Proteins 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 description 1
- HIQIXEFWDLTDED-UHFFFAOYSA-N 4-hydroxy-1-piperidin-4-ylpyrrolidin-2-one Chemical compound O=C1CC(O)CN1C1CCNCC1 HIQIXEFWDLTDED-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 102000004506 Blood Proteins Human genes 0.000 description 1
- 108010017384 Blood Proteins Proteins 0.000 description 1
- 229920000875 Dissolving pulp Polymers 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- FJWGYAHXMCUOOM-QHOUIDNNSA-N [(2s,3r,4s,5r,6r)-2-[(2r,3r,4s,5r,6s)-4,5-dinitrooxy-2-(nitrooxymethyl)-6-[(2r,3r,4s,5r,6s)-4,5,6-trinitrooxy-2-(nitrooxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-3,5-dinitrooxy-6-(nitrooxymethyl)oxan-4-yl] nitrate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O)O[C@H]1[C@@H]([C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@@H](CO[N+]([O-])=O)O1)O[N+]([O-])=O)CO[N+](=O)[O-])[C@@H]1[C@@H](CO[N+]([O-])=O)O[C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O FJWGYAHXMCUOOM-QHOUIDNNSA-N 0.000 description 1
- 230000021736 acetylation Effects 0.000 description 1
- 238000006640 acetylation reaction Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000000427 antigen Substances 0.000 description 1
- 108091007433 antigens Proteins 0.000 description 1
- 102000036639 antigens Human genes 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000005018 casein Substances 0.000 description 1
- BECPQYXYKAMYBN-UHFFFAOYSA-N casein, tech. Chemical compound NCCCCC(C(O)=O)N=C(O)C(CC(O)=O)N=C(O)C(CCC(O)=N)N=C(O)C(CC(C)C)N=C(O)C(CCC(O)=O)N=C(O)C(CC(O)=O)N=C(O)C(CCC(O)=O)N=C(O)C(C(C)O)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=O)N=C(O)C(CCC(O)=O)N=C(O)C(COP(O)(O)=O)N=C(O)C(CCC(O)=N)N=C(O)C(N)CC1=CC=CC=C1 BECPQYXYKAMYBN-UHFFFAOYSA-N 0.000 description 1
- 235000021240 caseins Nutrition 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 150000002334 glycols Chemical class 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- 150000002605 large molecules Chemical class 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005374 membrane filtration Methods 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000151 polyglycol Polymers 0.000 description 1
- 239000010695 polyglycol Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000012460 protein solution Substances 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000011877 solvent mixture Substances 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
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
- B01D71/08—Polysaccharides
- B01D71/10—Cellulose; Modified cellulose
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/147—Microfiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
- B01D63/02—Hollow fibre modules
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
- B01D63/02—Hollow fibre modules
- B01D63/021—Manufacturing thereof
Abstract
A microporous membrane which has pore diameters of from 0.01 to 5 mu m, an ultrafiltration capacity of from 40 to 2000 ml/m<2>. h . mm Hg and an adjustable exclusion limit for molecular weights of from 70,000 to 3 million and which comprises hydrate cellulose regenerated from cuoxam solutions to which polyethylene glycol having an average molecular weight of from 100 to 1500 has been added is disclosed. A process for the production of such a membrane which comprises extruding a cellulose cuoxam solution, the spinning solution containing a copper salt in a quantity of from 40 to 60%, by weight, of copper, based on the weight of the cellulose, ammonium in a quantity of from 50 to 300%, by weight, of ammonia, based on the weight of the cellulose, and from 30 to 400%, by weight, based on the weight of the cellulose, of polyethylene glycol having an average molecular weight of from 100 to 1500 and from 4 to 7%, by weight, of cellulose into a coagulation bath is also disclosed. The present membranes offer certain advantages particularly in plasmaphoresis and microfiltration.
Description
SPECIFICATION
Microporous cellulose membrane
This invention relates to a microporous cellulose membrane; more particularly, it relates to a microporous membrane in the form of flat films, tubular films or hollow filaments having pore diameters of from 0.01 to 5 ym and an ultrafiltration capacity of from 40 to 2000 ml/m2 ~ h mm Hg in which the exclusion limit is adjustable for molecular weights of from 70,000 to 3 million.
U.S. Patent No. 1,421,341 describes a filter consisting of a cellulose ester, for example cellulose acetate, and having pores suitable for the separation of bacteria, and also a process for the production of such a filter. The described filters may be dried without the pores collapsing.
The filters are produced by casting a solution of the cellulose ester in a solvent mixture and evaporating the solvent in a moist atmosphere at a low temperature. Water is added to the solvent in such a quantity that the mixture still dissolves the cellulose ester. The quantity of water added affects the size of the pores. The membrane obtained is washed in water, stretched while wet and dried after a heat treatment in hot water or steam.
German Patent No. 843,008 describes a process for the production of ultrafilters and diaphragms of plastics in which porosity is produced by the addition to a plastics solution suitable for producing a thin skin of salts soluble therein or other substances in a solution which is miscible with the plastics solution without entering into a reaction therewith, subsequently drying the mixture and removing the added substance from the skin thus produced by dissolution using a solvent which does not dissolve the plastic.
German Auslegeschrift No. 1,017,596 describes a process in which a cellulose acetate membrane is produced by the phase inversion process comprising pre-gelation in a ventilation chamber at a working temperature of from 20 to 40 C for a relative air humidity of from 50 to 70%.
U.S. Patent No. 2,783,894 describes a similar process for the production of a microporous membrane filter from nylon.
German Auslegeschrift No. 1,156,056 describes a process in which membranes of the type produced in accordance with the above-mentioned U.S. Patent Nos. 1,421,341 or 2,783,894 are applied in a particular way to a hollow body provided with perforations. The microporous films have pores the effective diameter of which is smaller than 10 #m and which, in all, occupy more than 80% of the total volume of the filter material.
German Patent No. 2,257,697 describes a porous cellulose acetate symmetrical membrane filter produced by dissolving cellulose acetate having a degree of acetylation of from 20 to 65.5% in an organic solvent in a ratio, by weight, of from 5 to 40% to the solvent and adding to the solution a diluting solvent, the boiling point of which is higher than that of the abovementioned organic solvent, and also a metal salt in a ratio, by weight, of from 20 to 200% to the acetate, resulting in the formation of a homogeneous solution which is applied to a flat, polished surface to form a thin film from which the solvent present is removed by evaporation and which is converted by microphase separation into its gel state, after which and finally the metal salt present therein is dissolved out to form the porous membrane.
The pore diameter amounts to from 0.01 to 10 cm and the porosities of from 70 to 81% are mentioned.
When a membrane of the type in question is magnified 6000 times under an electron microscope, it shows a structure which, from its surface, resembles a mat of filaments in which looped filaments projecting from common intersections lie irregularly over and adjacent one another. In cross-section, the structure inside the membrane represents a loose, but uniformly dense mass.
German Offenlegungsschrift No. 2,606,244 describes a hollow fibre for membrane filtration of a synthetic or semi-synthetic, chain-like high polymer which forms filaments when spun, the cylindrical wall forming the hollow fibre, at least in an uninterrupted region resembling a circular bapd in cross-section, having a three-dimensional net-like structure of fine filter channels having a pore ratio of at least 55% as the active filter zone.
The pores are said to have a diameter of from 1 to 0.01 ym. Particles having a molecular weight of up to 2,400,000 are said to lend themselves to effective separation by the membrane. Membranes of the type in question may be produced from cellulose acetate, polyvinyl chloride, polyacrylonitrile or polyamide.
German Offenlegungsschrift No. 2,823,985 describes a dialysis membrane which is distinguished by the fact that it consists of regenerated cellulose regenerated from cuoxam solutions and having an ultrafiltration capacity of from 7 to 30 ml/h ~ m2 ~ mm Hg (corresponding to from 14 to 60 pm ~ s-' 1 Pa - 1) and an average molecule permeability of from 4 103 to 1 2 10-3 cm/min (corresponding to from 0.65 to 2.0 ym
According to German Offenlegungsschrift No. 28,23 985, membranes of the type in question may be produced by a process in which finely ground CuO is added to a cellulose-cuoxam solution and washed out again with hot sulphuric acid after coagulation.In a membrane of this type, the molecular weight exclusion limit is below 60,000 because the passage of blood proteins and other high molecular weight constituents of blood is effectively prevented and the molecular weight of the albumin in blood amounts to from 60,000 to 70,000.
Although there are may types of microporous membranes the pores of which may be adjusted in the required manner by various measures, there was a considerable need to produce a membrane of this type from hydrate cellulose regenerated from cuoxam solutions. The results of tests which have been conducted so far have mostly been negative or are comparable with the results obtained, for example, with the membranes according to German Offenlegungsschrift
No. 2,823,985. In these tests, alcohols, such as methanol, ethanol and isopropanol, and also glycols, such as propylene glycol and butyl glycol, also such compounds as dimethyl formamide, ethoxylated fatty alcohols and nonyl phenyl polyglycol ethers, were added to the cellulosecuoxam solution, but did not improve effectiveness by comparison with microfilters or increase the exclusion limit.With polypropylene glycols (molecular weight 1200; ratio of PPG to cellulose 0.1 to 1) it was not possible to produce a homogeneous spinning solution.
By virtue of the particularly high compatibility with blood of regenerated cellulose regenerated from cuoxam solutions, there have been repeated demands in specialist circles for a microporous membrane comparable in its filter properties to known microporous membranes to be produced from regenerated cellulose. Accordingly, there has also been no shortage of attempts to produce such a membrane. Although may other spinning solution additives have been tested, none has proved successful. In addition to the substances mentioned, long-chain fatty alcohols, esters, dioxane, quaternary ammonium salts, casein, silica gel and zeolites have also been added to the spinning solution in various concentrations, but without any success.
In some cases, it was not possible to prepare homogeneous mixtures of the above-mentioned substances with the cuoxam solution. Although some of the mixtures were homogeneous, they could not be spun. However, some of the additives even resulted in coagulation of the cuoxam solution. A homogeneous spinning solution is to be understood to be a solution in which no phase separation is discernible to the naked eye.
It has now surprisingly been found that it is possible after all to produce a microporous membrane in the form of flat films, tubular films or hollow filaments having pore diameters of from 0.01 to 5 #m and an ultrafiltration capacity of from 40 to 2000 ml/m2 ~ h ~ mm Hg, in which the exclusion limit is adjustable for molecular weights of from 70,000 to 3 million and which is characterised in that it consists of hydrate cellulose regenerated from cuoxam solutions to which polyether glycol having an average molecular weight of from 100 to 1500 has been added.Since the addition of a relatively large number of substances to cuoxam solutions did not result in the formation of microporous membranes comparable with the known microporous membranes, it was also surprising to find that it is possible to produce such membranes by the process according to the present invention which is distringuished by the fact that the spinning solution contains a copper salt in a quantity of from 40 to 60%, by weight, of copper, based on the weight of the cellulose, ammonium in a quantity of from 50 to 300%, by weight, of ammonia, based on the weight of the cellulose, from 30 to 400%, by weight, based on the weight of the cellulose, of polyethylene glycol having an average molecular weight of from 100 to 1500 and from 4 to 7%, by weight, of cellulose.
In one embodiment, the cellulose is coagulated in an acid medium. In this embodiment, therefore, the process according to the present invention is further distinguished by the fact that a water-diluted acid is used as the coagulation bath.
Dilute sulphuric acid is preferably used for the coagulation bath. In this embodiment of the present invention, the concentration of sulphuric acid amounts to from 30 to 300 g/l.
Coagulation is preferably carried out at slightly higher temperatures, the temperature of the coagulation bath being from 30 to 65 C.
Where coagulation of the cellulose-cuoxam solution is carried out in an acid medium, it has been found that the ultrafiltration capacity increases to an unexpected extent for standard wall thicknesses of the microporous membrane. Accordingly, it is possible to produce microporoup membranes which have very high ultrafiltration capacities and, at the same time, relatively thick membrane walls. The greater wall thickness of the membrane naturally provides it with correspondingly greater strength.
In some of the applications for microporous membranes, it is desirable to use membranes having a relatively low molecular weight exclusion limit and, correspondingly, a relatively low molecular weight capacity. Membranes of this type may be advantageously produced in another embodiment in which coagulation is carried out in an alkaline medium. In this embodiment, therefore, the process according to the present invention is further distinguished by the fact that a water-dilute alkali metal hydroxide is used as the coagulation bath.
The coagulation bath is preferably formed by dilute sodium hydroxide. In this embodiment of the present invention, the concentration of the sodium hydroxide is from 60 to 140 g/l.
Where alkaline coagulation baths are used, the process according to the present invention is carried out in such a way that the temperature of the coagulation bath is from 15 to 30 C.
The temperature is preferably from 20 to 25 C.
The polyethylene glycol used may be optimally mixed in if the ratio, by weight, of polyethylene glycol to cellulose is lower than calculated in accordance with the following equation:
0.59 V ~ ~3.3 Iog MW+ 10.9 log MW wherein MW is the molecular weight of the polyethylene glycol used.
It is of particular advantage to prepare the spinning solution by mixing and homogenising a cellulose-cuoxam solution having a correspondingly higher cellulose concentration with a solution of polyethylene glycol in water and ammonia.
The cellulose-cuoxam solution is preferably mixed and homogenised with the solution of polyethylene glycol in ammonia immediately before the spinneret.
The purpose for which the microporous membrane according to the present invention may be used with particular advantage by virtue of the high compatibility with blood of cellulose regenerated by the cuoxam process is plasmaphoresis, i.e. the separation of blood plasma from cellular constituents, and also the further separation of plasma constituents according to molecular weight.
By virtue of the hydrophilic character of cellulose and hence of the membrane according to the present invention, the present membrane may be used particularly successfully for microfiltration, for example for the sterilisation of aqueous solutions or suspensions and for the treatment of effluents.
Where it is used for haemodialysis and haemofiltration the membrane should not allow any proteins to pass through. Albumin is the most common protein in plasma and has the lowest molecular weight (approximately 68,000). Accordingly, the membrane must be impermeable to molecules of this size in haemodialysis and haemofiltration.
Medicinal research has shown that some illnesses are caused by toxins which are frequently fixed to proteins, but which themselves are small molecules which would easily pass through the above-mentioned dialysis and haemofiltration membranes if they were present in free form.
However, the fact that they are fixed to proteins means that they represent such large molecules that they cannot be eliminated by standard dialysis membranes. Immuno-complexes and antigens also have correspondingly high molecular weights.
Hitherto, protein-fixed toxins of this type having molecular weights of from 100,000 to 3 million have largely been removed by the method of plasma separation using ultracentrifuges.
However, there are also a few types of membrane which have been used for this purpose, including in particular cellulose acetate, cellulose nitrate and polyvinyl alcohol membranes.
However, membranes of this type have more of a decelerated or, more precisely, only partial permeability to the above-mentioned proteins. Permeability may be expressed by the so-called screening coefficient:
wherein
CF is the concentration of the substance X in the filtrate and
CB is the concentration of the substance X in the blood.
The screening coefficient may be determined for example by laser-nephelometric methods.
Il S = 1, complete permeability prevails. If S is less than 1, partial permeability prevails. The membranes available at the present time have screening coefficients which, even for albumin, amount to less than 0.8. This means that the constituents to be separated are only eliminated to a reduced extent. Because of this, a longer treatment time is required. It is also necessary to use larger quantities of reinfusions or very large membranes which involves considerable disadvantages because, in that case, the modules have a very high extracorporeal volume.
In addition to the screening coefficient, the ultrafiltration capacity is a measure of the permeability properties of a membrane. The ultrafiltration capacity of a membrane is determined by measuring the volume of liquid which flows through the membrane over an area determined by the apparatus for a given pressure difference and at a temperature of 37 C and which, for the purpose of general comparability, is standardised to unit area, unit time and unit pressure.
Physiological saline is used as the liquid. The method in question is described in "Evaluation of
Hemodialyzers and Dialysis Membranes" issued by the U.S. Department of Health, Education and Welfare, DHEW Publication No. (NIH) 77-1294, pages 24 to 26.
If a protein solution, for example a 1 % albumin solution, is used instead of the physiological saline, trans-membrane flow of the corresponding protein through the membrane is obtained for a given pressure difference, for example 0.1 bar.
The present invention is illustrated by the following Examples which show in particular how any change in the process conditions affects the microporous membrane.
EXAMPLE 1
A cellulose-cuoxam solution containing 9.2%, by weight, of cellulose, 6.2%, by weight, of
NH3 and 3.9%, by weight, of Cu (in the form of Cu(NH4)3S04) and water was prepared and dearated. The solution had a density of 1.08 g/cc. A solution was prepared from 10 litres of a 30% ammonia solution, 5 litres of polethylene glycol (MW 400) and 2 litres of water and delivered by means of a metering pump to a "Pentax" mixer at a rate of 164 ml/minute. At the same time, 180 ml/minute of the cellulose cuoxam solution was delivered to the "Pentax" mixer and mixed and homogenised therein to form a spinning solution containing 5.1%, by weight, of cellulose, 11.0%, by weight, of NH3, 15.0%, by weight, of PEG and 2,16%, by weight, of Cu.The spinning solution was then extruded through the annular slot of a hollowfilament spinneret into a coagulation bath containing 112 g/l of NaOH at 25 C while at the same time isopropyl myristate was delivered to the central bore of the spinneret. The spinning rate amounted to 42 m/minute.The hollow-filament membrane obtained has the following properties after the removal of copper, washing, softening in a softening bath containing 25 g/l of glycerol and 400 g/l of isopropanol in water and drying in air at 90 C: External diameter 260 ym Internal diameter 220 m
Tensile strength 18.1 103 cN/mm2
Breaking elongation 27.5%
Ultrafiltration capacity 271 ml/m2 ~ h ~ mm Hg
The same spinning solution was extruded into a coagulation bath containing 80 g/l of H2SO4 at 30 C under otherwise the same conditions.
The hollow-filament membrane formed had the following properties:
External diameter 329 ym Internal diameter 227 pm Tensile strength 13.3 ~ 103 cN/mm2
Breaking elongation 31.7 %
Ultrafiltration capacity 901 ml/m2 ~ h ~ mm Hg
Screening coefficient for albumin MW 68,000 100%
Transmembrane flow 1 % of albumin, 0.1 bar= 580 ml/min ~ m2
EXAMPLE 2
Following the same procedure as in Example 1, 180 ml/minute of the deaerated cellulosecuoxam solution and 164 ml/minute of a solution of 10 litres of 30 % ammonia solution, 1.7 litre of polyethylene glycol (MW 400) and 5.3 litres of water were delivered to the "Pentax"mixer and the resulting mixture spun at a rate of 42 m/minute to form hollow-filament membranes.The spinning solution had the following composition: 5.12%, by weight, of cellulose, 5,1 2%, by weight, of polyethylene glycol, 2.1 7% by weight, of Cu and 11.1 6%, lay weight, of NH3. If a dilute sodium hydroxide solution having a concentration of 112 g/l NaOH and a temperature of 25 C is used as the coagulation bath, a hollow-filament membrane having the following properties is obtained after the removal of copper, washing, softening and dryiog: :
External diameter 244 lim Internal diameter 210 #m Tensile strength 17.8 ~ 103 cN/mm2
Breaking elongation 31.1% Ultrafiltration capacity 32.8 ml/m2 ~ h ~ mm Hg
If the spinning solution is spun into an acid coagulation bath containing 180 9/1 of H2SO4 at 45 C under otherwise the same conditions, the hollow-filament membrane has the following properties after the removal of copper, washing, softening and drying::
External diameter 320 lim Internal diameter 210 jum Tensile strength 14.0 ~ 103 cN/mm2
Breaking elongation 27.0%
Ultrafiltration capacity 301 ml/m2 ~ h ~ mm Hg
Screening coefficient for albumin MW 68,000 99.2%
Transmembrane flow for 1% albumin, 0.1 bar = 253 ml/min ~ m2
EXAMPLE 3
Comparison of the ultrafiltration capacities obtained with different concentrations of ammonia in the spinning solution and with different wall thicknesses reveals characteristic differences depending on the precipitation medium used and on whether the spinning solution was spun into an alkaline coagulation bath or into an acid coagulation bath.The cellulose content of the spinning solutions amounted to 5.1%, by weight, the copper content of 42.4%, based on the celloluse content, and the polyethylene (molecular weight 400) content to 295%, based on the cellulose content. The NH3-content amounted to from 70 to 255%. based on the cellulose content. The ultrafiltration capacity was measured in dependence upon the wall thickness of the hollow filaments. Production was carried out under otherwise the same conditions as in
Examples 1 and 2. The results are set out in the following Table.
Ultrafiltration
Wall thickness capacity
NH3 m) Coagulation mi/m2 ~ h ~ mm Hg a 70.6% 4 65 g/l of NaOH 35 b 70.6% 16 65 g/l of NaOH 15 c 70.6% 9 180 g/l of H2SO4 350 d 70.6% 16 180 g/l of H2SO4 160 e 120 % 16 65 g/l of NaOH 75 f 120 % 4 65 g/l of NaOH 25 g 120 % 9 180g/lofH2SO4 400 h 120 % 40 180g/lofH2SO4 30
198 % 16 65 g/l of NaOH 110 k 198 % 4 65 g/l of NaOH 50 1 198 % 7 180g/lofH2SO4 720 m 198 % 32 180g/lofH2SO4 125 n 225 % 18 65 g/l of NaOH 130 o 225 % 4 65 g/l of NaOH 60 p 225 % 13 180g/lofH2SO4 1000 q 225 % 18 180g/lofH2SO4 160
Claims (20)
1. A microporous membrane which has pore diameters of from 0.01 to 5 #m, an ultrafiltration capacity of from 40 to 2000 ml/m2 ~ h ~ mm Hg and an adjustable exclusion limit for molecular weights of from 70,000 to 3 million and which comprises hydrate cellulose regsenerated from cuoxam solutions to which polyethylene glycol having an average molecular weight of from 100 to 1500 has been added.
2. A membrane as claimed in claim 1 in the form of flat films, tubular films or hollow filaments.
3. A membrane as claimed in claim 1 substantially as herein described.
4. A process for the production of a membrane as claimed in claim 1 which comprises extruding a cellulose-cuoxam solution, the spinning solution containing a copper salt in a quantity of from 40 to 60%, by weight, of copper, based on the weight of the cellulose, ammonium in a quantity of from 50 to 300%, by weight, of ammonia, based on the weight of the cellulose, and from 30 to 400%, by weight, based on the weight of the cellulose, of polyethylene glycol having an average molecular weight of from 100 to 1500 and from 4 to 7%, by weight, of cellulose into a coagulation bath.
5. A process as claimed in claim 4, in which an acid diluted with water is used as the coagulation bath.
6. A process as claimed in claim 5, in which the coagulation bath comprises dilute sulphuric acid.
7. A process as claimed in claim 6, in which the concentration of sulphuric acid amounts to from 30 to 300 g/l.
8. A process as claimed in any of claims 4 to 7 in which the temperature of the coagulation bath is from 30 to 65 C.
9. A process as claimed in claim 4, in which a water-diluted alkali metal hydroxide is used as the coagulation bath.
10. A process as claimed in claim 9 in which the coagulation bath comprises dilute sodium hydroxide.
11. A process as claimed in claim 10, in which the concentration of the sodium hydroxide amounts to from 20 to 200 g/l.
12. A process as claimed in claim 11, in which the concentration of the sodium hydroxide amounts to from 60 to 140 g/l.
13. A process as claimed in any of claims 4 or 9 to 12 in which the temeprature of the coagulation bath is from 15 to 30 C.
14. A process as claimed in claim 13, in which the temperature is from 20 to 25 C.
15. A process as claimed in any of claims 4 to 14, in which the ratio, by weight, of polyethylene glycol to cellulose is lower than calculated in accordance with the following equation:
0.59 V= - ------- ~ 3.3 . log MW+ 10.9 log MW wherein MW is the molecular weight of the polyethylene glycol used.
16. A process as claimed in any of claims 4 to 15, in which the spinning solution is prepared by mixing and homogenising a cellulose-cuoxam solution having a correspondingly higher cellulose concentration with a solution of polyethylene glycol in water and ammonia.
17. A process as claimed in claim 16, in which the cellulose-cuoxam solution is mixed and homogenised with the solution of polyethylene glycol in ammonia immediately before extrusion through a spinneret.
18. A process as claimed in claim 4 substantially as herein described.
19. The use of a membrane as claimed in any of claims 1 to 3 for plasmaphoresis.
20. The use of a membrane as claimed in any of claims 1 to 3 for microfiltration.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803042110 DE3042110A1 (en) | 1980-11-07 | 1980-11-07 | MICROPOROUS CELLULOSE MEMBRANE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2086798A true GB2086798A (en) | 1982-05-19 |
| GB2086798B GB2086798B (en) | 1984-07-18 |
Family
ID=6116246
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8133372A Expired GB2086798B (en) | 1980-11-07 | 1981-11-05 | Microporous cellulose membrane |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS57108101A (en) |
| DE (1) | DE3042110A1 (en) |
| FR (1) | FR2499866B1 (en) |
| GB (1) | GB2086798B (en) |
| IT (1) | IT1142925B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0351773A2 (en) * | 1988-07-20 | 1990-01-24 | Asahi Kasei Kogyo Kabushiki Kaisha | Hollow fiber membrane |
| EP0359636A2 (en) * | 1988-09-07 | 1990-03-21 | Terumo Kabushiki Kaisha | Hollow cellulose fibers, method for making, and fluid processing apparatus using same |
| EP0488063A1 (en) * | 1990-11-30 | 1992-06-03 | Akzo Nobel N.V. | Cellulose dialysis hollow fibres |
| US5853647A (en) * | 1996-03-07 | 1998-12-29 | Akzo Nobel Nv | Process for the stabilization of the properties of cellulosic membranes |
| CN114130210A (en) * | 2021-11-24 | 2022-03-04 | 天津工业大学 | Preparation method of layer-by-layer self-assembled antibacterial hydrogel filtering membrane |
| CN117679962A (en) * | 2023-09-29 | 2024-03-12 | 杭州科百特过滤器材有限公司 | Cellulose virus-removing filter membrane and preparation process and application thereof |
| CN117679962B (en) * | 2023-09-29 | 2024-05-14 | 杭州科百特过滤器材有限公司 | Cellulose virus-removing filter membrane and preparation process and application thereof |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4581140A (en) * | 1981-11-25 | 1986-04-08 | Asahi Kasei Kogyo Kabushiki Kaisha | Porous regenerated cellulose membrane and process for the preparation thereof |
| JPS59204911A (en) * | 1983-05-02 | 1984-11-20 | Asahi Chem Ind Co Ltd | Regenerated cellulose hollow fiber of novel structure |
| DE3317037A1 (en) * | 1983-05-10 | 1984-11-15 | Hoechst Ag, 6230 Frankfurt | REGENERATED CELLULOSE MEMBRANE WITH IMPROVED DIFFUSION PROPERTIES AND METHOD FOR PRODUCING THE SAME |
| JPS61106168A (en) * | 1984-10-30 | 1986-05-24 | 帝人株式会社 | Permselective hollow yarn membrane, its production and serum component separator using the same |
| JPS61293469A (en) * | 1985-06-21 | 1986-12-24 | 帝人株式会社 | Permselective hollow yarn membrane and serum component separator using the same |
| JPH0613087B2 (en) * | 1985-10-18 | 1994-02-23 | テルモ株式会社 | Hemodialyzer |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3888771A (en) * | 1972-06-02 | 1975-06-10 | Asahi Chemical Ind | Hollow fibers of cuprammonium cellulose and a process of the manufacture of same |
| DE2419930A1 (en) * | 1973-04-30 | 1974-11-07 | Dorr Oliver Inc | ULTRAFILTRATION MEMBRANE AND METHOD OF MANUFACTURING THEREOF |
| JPS5193786A (en) * | 1975-02-15 | 1976-08-17 | Makurokagatano chukuseni | |
| JPS5812932B2 (en) * | 1977-06-30 | 1983-03-10 | 日本ゼオン株式会社 | Hollow fiber manufacturing method |
| DE2816085B2 (en) * | 1978-04-13 | 1981-04-23 | Sartorius GmbH, 3400 Göttingen | Asymmetrical ultrafiltration membrane based on cellulose hydrate |
| DE2823985C2 (en) * | 1978-06-01 | 1986-01-02 | Akzo Gmbh, 5600 Wuppertal | Dialysis membrane |
| JPS5584503A (en) * | 1978-12-19 | 1980-06-25 | Teijin Ltd | Preparing cellulose ester based selective permeable membrane |
| DE3002438C2 (en) * | 1979-01-26 | 1982-04-08 | Asahi Kasei Kogyo K.K., Osaka | Selectively permeable membrane |
| DD143037A1 (en) * | 1979-04-11 | 1980-07-30 | Gensrich Heinz Juergen | Cellulosic granules and process for their preparation |
| CA1153171A (en) * | 1979-12-17 | 1983-09-06 | David T. Chen | Cellulose semipermeable hollow fibers and method for making same |
| DE3006880C2 (en) * | 1980-02-23 | 1986-10-09 | Akzo Gmbh, 5600 Wuppertal | Plasmaphoresis membrane |
-
1980
- 1980-11-07 DE DE19803042110 patent/DE3042110A1/en active Granted
-
1981
- 1981-11-03 IT IT49622/81A patent/IT1142925B/en active
- 1981-11-05 GB GB8133372A patent/GB2086798B/en not_active Expired
- 1981-11-05 FR FR8120762A patent/FR2499866B1/en not_active Expired
- 1981-11-06 JP JP56177298A patent/JPS57108101A/en active Granted
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0351773A2 (en) * | 1988-07-20 | 1990-01-24 | Asahi Kasei Kogyo Kabushiki Kaisha | Hollow fiber membrane |
| EP0351773A3 (en) * | 1988-07-20 | 1990-03-28 | Asahi Kasei Kogyo Kabushiki Kaisha | Hollow fiber membrane |
| EP0359636A2 (en) * | 1988-09-07 | 1990-03-21 | Terumo Kabushiki Kaisha | Hollow cellulose fibers, method for making, and fluid processing apparatus using same |
| EP0359636A3 (en) * | 1988-09-07 | 1990-03-28 | Terumo Kabushiki Kaisha | Hollow cellulose fibers, method for making, and fluid processing apparatus using same |
| US5084349A (en) * | 1988-09-07 | 1992-01-28 | Terumo Kabushiki Kaisha | Hollow cellulose fibers, method for making, and fluid processing apparatus using same |
| EP0488063A1 (en) * | 1990-11-30 | 1992-06-03 | Akzo Nobel N.V. | Cellulose dialysis hollow fibres |
| US5192440A (en) * | 1990-11-30 | 1993-03-09 | Akzo N.V. | Hollow cellulose dialysis fibers |
| US5853647A (en) * | 1996-03-07 | 1998-12-29 | Akzo Nobel Nv | Process for the stabilization of the properties of cellulosic membranes |
| CN114130210A (en) * | 2021-11-24 | 2022-03-04 | 天津工业大学 | Preparation method of layer-by-layer self-assembled antibacterial hydrogel filtering membrane |
| CN114130210B (en) * | 2021-11-24 | 2023-12-22 | 宁波灏钻科技有限公司 | Preparation method of layer-by-layer self-assembled antibacterial hydrogel filtering membrane |
| CN117679962A (en) * | 2023-09-29 | 2024-03-12 | 杭州科百特过滤器材有限公司 | Cellulose virus-removing filter membrane and preparation process and application thereof |
| CN117679962B (en) * | 2023-09-29 | 2024-05-14 | 杭州科百特过滤器材有限公司 | Cellulose virus-removing filter membrane and preparation process and application thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| IT8149622A0 (en) | 1981-11-03 |
| DE3042110C2 (en) | 1989-08-17 |
| FR2499866A1 (en) | 1982-08-20 |
| DE3042110A1 (en) | 1982-06-16 |
| FR2499866B1 (en) | 1985-10-25 |
| JPS57108101A (en) | 1982-07-06 |
| IT1142925B (en) | 1986-10-15 |
| JPH025132B2 (en) | 1990-01-31 |
| GB2086798B (en) | 1984-07-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |