GB2198739A - Microporous membrane - Google Patents
Microporous membrane Download PDFInfo
- Publication number
- GB2198739A GB2198739A GB08727216A GB8727216A GB2198739A GB 2198739 A GB2198739 A GB 2198739A GB 08727216 A GB08727216 A GB 08727216A GB 8727216 A GB8727216 A GB 8727216A GB 2198739 A GB2198739 A GB 2198739A
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- GB
- United Kingdom
- Prior art keywords
- membrane
- polyetherimide
- solvent
- polymer
- molecular weight
- 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.)
- Granted
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- 239000012982 microporous membrane Substances 0.000 title claims abstract description 13
- 239000012528 membrane Substances 0.000 claims abstract description 89
- 239000002904 solvent Substances 0.000 claims abstract description 64
- 229920001601 polyetherimide Polymers 0.000 claims abstract description 45
- 239000004697 Polyetherimide Substances 0.000 claims abstract description 43
- 239000007788 liquid Substances 0.000 claims abstract description 22
- 238000005266 casting Methods 0.000 claims abstract description 18
- 239000000126 substance Substances 0.000 claims abstract description 18
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 150000004985 diamines Chemical class 0.000 claims abstract description 9
- 125000003118 aryl group Chemical group 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 34
- 229920000642 polymer Polymers 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- -1 ether anhydride Chemical class 0.000 claims description 8
- 239000003431 cross linking reagent Substances 0.000 claims description 7
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical group CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 6
- 229920002873 Polyethylenimine Polymers 0.000 claims description 6
- 238000009835 boiling Methods 0.000 claims description 5
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 claims description 5
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 claims description 4
- 125000000843 phenylene group Chemical group C1(=C(C=CC=C1)*)* 0.000 claims description 4
- 125000005543 phthalimide group Chemical group 0.000 claims description 4
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 3
- MQAHXEQUBNDFGI-UHFFFAOYSA-N 5-[4-[2-[4-[(1,3-dioxo-2-benzofuran-5-yl)oxy]phenyl]propan-2-yl]phenoxy]-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(OC2=CC=C(C=C2)C(C)(C=2C=CC(OC=3C=C4C(=O)OC(=O)C4=CC=3)=CC=2)C)=C1 MQAHXEQUBNDFGI-UHFFFAOYSA-N 0.000 claims description 3
- 150000001412 amines Chemical class 0.000 claims description 3
- 238000000605 extraction Methods 0.000 claims description 3
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 2
- ZHDTXTDHBRADLM-UHFFFAOYSA-N hydron;2,3,4,5-tetrahydropyridin-6-amine;chloride Chemical group Cl.NC1=NCCCC1 ZHDTXTDHBRADLM-UHFFFAOYSA-N 0.000 claims description 2
- 238000011065 in-situ storage Methods 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000011574 phosphorus Substances 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- 239000002202 Polyethylene glycol Substances 0.000 claims 1
- 238000007259 addition reaction Methods 0.000 claims 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 claims 1
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical group N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 claims 1
- 229920003169 water-soluble polymer Polymers 0.000 claims 1
- 239000011148 porous material Substances 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- 239000000463 material Substances 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 239000000243 solution Substances 0.000 description 8
- 238000001704 evaporation Methods 0.000 description 7
- 230000008020 evaporation Effects 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000001035 drying Methods 0.000 description 4
- 238000009472 formulation Methods 0.000 description 4
- 239000011800 void material Substances 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-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
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 229920002678 cellulose Polymers 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- 238000001471 micro-filtration Methods 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- 229940068918 polyethylene glycol 400 Drugs 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 2
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- 229920002302 Nylon 6,6 Polymers 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 229920004738 ULTEM® Polymers 0.000 description 2
- 229920004747 ULTEM® 1000 Polymers 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 150000001728 carbonyl compounds Chemical class 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000004807 desolvation Methods 0.000 description 2
- NHWGPUVJQFTOQX-UHFFFAOYSA-N ethyl-[2-[2-[ethyl(dimethyl)azaniumyl]ethyl-methylamino]ethyl]-dimethylazanium Chemical compound CC[N+](C)(C)CCN(C)CC[N+](C)(C)CC NHWGPUVJQFTOQX-UHFFFAOYSA-N 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 229920000768 polyamine Polymers 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000000108 ultra-filtration Methods 0.000 description 2
- AJDIZQLSFPQPEY-UHFFFAOYSA-N 1,1,2-Trichlorotrifluoroethane Chemical compound FC(F)(Cl)C(F)(Cl)Cl AJDIZQLSFPQPEY-UHFFFAOYSA-N 0.000 description 1
- YJTKZCDBKVTVBY-UHFFFAOYSA-N 1,3-Diphenylbenzene Chemical group C1=CC=CC=C1C1=CC=CC(C=2C=CC=CC=2)=C1 YJTKZCDBKVTVBY-UHFFFAOYSA-N 0.000 description 1
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical compound CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 description 1
- XKTYXVDYIKIYJP-UHFFFAOYSA-N 3h-dioxole Chemical compound C1OOC=C1 XKTYXVDYIKIYJP-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 241000589539 Brevundimonas diminuta Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000004320 controlled atmosphere Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 229940113088 dimethylacetamide Drugs 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- DUIHIDNLDMIFPA-UHFFFAOYSA-N ethanol;2-ethoxyethanol Chemical compound CCO.CCOCCO DUIHIDNLDMIFPA-UHFFFAOYSA-N 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 239000003906 humectant Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- DGEYTDCFMQMLTH-UHFFFAOYSA-N methanol;propan-2-ol Chemical compound OC.CC(C)O DGEYTDCFMQMLTH-UHFFFAOYSA-N 0.000 description 1
- CXHHBNMLPJOKQD-UHFFFAOYSA-M methyl carbonate Chemical compound COC([O-])=O CXHHBNMLPJOKQD-UHFFFAOYSA-M 0.000 description 1
- XYDYWTJEGDZLTH-UHFFFAOYSA-N methylenetriphenylphosphorane Chemical compound C=1C=CC=CC=1P(C=1C=CC=CC=1)(=C)C1=CC=CC=C1 XYDYWTJEGDZLTH-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000002952 polymeric resin Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 150000003335 secondary amines Chemical group 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 229950011008 tetrachloroethylene Drugs 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 230000004584 weight gain Effects 0.000 description 1
- 235000019786 weight gain Nutrition 0.000 description 1
- 239000000080 wetting agent 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
- B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
- B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
- B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
- B01D71/643—Polyether-imides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
- B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
-
- 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
- B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
- B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
- B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
-
- 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
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1046—Polyimides containing oxygen in the form of ether bonds in the main chain
- C08G73/1053—Polyimides containing oxygen in the form of ether bonds in the main chain with oxygen only in the tetracarboxylic moiety
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/38—Graft polymerization
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Transplantation (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
A microporous membrane for use in filtration, is formed of a polyetherimide derived from an aromatic bis (ether anydride) and an organic diamine. The membrane is formed from a casting liquid comprising the polyetherimide together with a solvent and a non-solvent, forming a thin layer of the liquid and extracting at least part of the solvent and non-solvent to form the required membrane. The membrane may be modified by the inclusion of additional chemical moieties.
Description
MICROPOROUS MEMBRANE
This invention relates to a microporous membrane for use in filtration, and to a method of forming a microporous membrane. Synthetic polymeric microporous membranes are now well-known for use in filtration, and there is abundant literature on the subject. The most comprehensive treatment is probably the work of R E Kesting, entitled "Synthetic Polymeric Membranes", published by the McGraw-Hill
Book Company 1971. This discloses many different types of polymer from which such membranes can successfully be formed.
There is, however, a constant need for microporous membranes which have excellent chemical resistance to a wide range of materials and which also exhibit good physical properties such as high tensile strength, flexibility and thermal stability. The presently most used membrane materials are those such as cellulose esters, nylons and polysulphones, each of which are limited in either their chemical or physical properties or both.
According to the present invention a microporous membrane for use in filtration is formed of a polyetherimide derived from an aromatic bis (ether anhydride) and an organic diamine, and having the formula
wherein n is an integer from 1 to 8, the positions of the oxygen atoms linking the phenylene and phthalimide rings are selected from the 3, 3 ; 4, 4 or 3, 4 positions and mixtures thereof, and m is any integer.
Polyetherimides as set out above are, in themselves, known, being described for example in US-A-3847867 and US A-3991004. Engineering polymer resins of polyetherimide have been marketed for many years under the registered trade mark ULTEM by the General Electric Co. Until now, however, the material has not been suggested for use as a microporous membrane. It has been found that membranes made from these materials, particularly the preferred polyetherimides as will hereafter be described, have excellent chemical resistance, including resistance to acid and base hydrolysis and resistance to a great number of organic solvents. In addition, the resins exhibit excellent physical properties, such as high tensile strength and toughness, good flexibility and dimensional stability over a range of temperatures from -100C to 1750C.
They also maintain their strength over the same temperature range.
Preferably the aromatic bis (ether anhydride) is 2, 2 bis [4-(3, 4-dicarboxy phenoxy) phenyl] propane dianhydride (hereinafter abbreviated to BPADA). Desirably the organic diamine is either 4, 4 diamino diphenyl ether or metaphenylene diamine (hereinafter abbreviated respectively to ODA and m-PD).
In the preferred embodiment the polyetherimide is formed by reacting B#ADA and m-PD to form a polymer represented by Formula 1 wherein the C nH 2n group is C3H6 and the oxygens linking the phenylene and phthalimide rings are in the 4, 4 positions.
The polyetherimide may have any suitable average molecular weight, desirably from about 10,000 to about 1,000,000, and preferably from about 20,000 to about 60,000 with the range of 30,000 to 40,000 being particularly preferred. Polymers of this type are sold in various forms under the registered trade mark ULTEM.
Microporous membranes according to the invention may be used as membrane filters in microfiltration or ultrafiltration. The membrane filters may be produced in the form of flat sheets or ribbons, in tubular form on either the inside or the outside of a supporting tube, in the form of hollow fibres or in the form of beaded particles. They may also be used in any filter construction designed to employ microporous membranes.
According to a particularly advantageous feature of the invention, the basic membrane is modified by having at least one additional chemical moiety grafted on to the polyetherimide by reaction with a carbonyl group thereof.
The chemistry of carbonyl compounds is well known, and can be referenced from any standard organic chemistry text book such as "Organic Chemistry" by John McMurray published by
Brook/Cole Publishing Company, 1984. Although the ability of carbonyl compounds to undergo a large number of different chemical reactions is well known, it is unexpected that the membranes of the invention can undergo these reactions without substantially altering the physical structure of the membrane.
The additional chemical moiety is desirably selected from HCN, amines, such as tetraethyl pentamine or polyethyleneimine and phosphorus ylides, such as methylenetriphenyl phosphorane and retinylidene triphenyl pLosphor#ne. The basic schemes of the three reactions can be described as follows:
1. Addition of HCN:
In a second type of modified membrane the polyetherimide is impregnated with a polymer which is immobilised within the porous structure of the polyetherimide by a cross linking agent. The polymer is preferably water-soluble, and is desirably either polyethyleneimine, polyamino-polyamine epichlorohydrin or a polyacrylamide.
The purpose of modifying the basic membrane is to make it more effective for its intended application. Thus, the membrane can be tailored to have particular chemical properties or particular utility in dealing with the filtration of given materials. For example, for the filtration of negatively charged particles such as silica or bacteria, it is beneficial to have a positively charged membrane.
According to another aspect of the invention a method of forming a microporous membrane for use in filtration comprises the steps of forming a casting liquid comprising a) a polyetherimide derived from an aromatic bis (ether anhydride) and an organic diamine and having formula (I) above; b) a solvent for the polyetherimide; and cj a non-solvent liquid that by itself cannot dissolve the c'yetherimide; forming a thin layer of the liquid; and extracting at least part of the solvent and non-solvent from the layer to form the required membrane.
Preferably the diamine is present in a concentration of up to 30% by weight of the polyetherimide. Preferably the polyetherimide is soluble to the extent of at least 1% by weight, desirably more than 10% by weight, in the solvent. Desirably, the non-solvent should be mutually soluble together with the polyetherimide to at least 0.5% by weight.
Preferably the non-solvent is soluble in the solvent and has a boiling point at least 200C higher than that of the solvent. The solvent will generally be extracted by evaporation, and the non-solvent may be leached from the cast film with a fluid which is a non-solvent for the polyetherimide. This leaves a microporous membrane which has excellent chemical and physical characteristics, the physical characteristics being varied by controlling the nature and amount of the solvent and the non-solvent as well as the process variables.
The phase inversion process for fabricating polymeric membranes is well known, and the broad principles of the process are discussed in Kesting's work "Synthetic
Polymeric Membranes", referred to above. Briefly, the process consists, in the context of the present invention, of dissolving the polyetherimide and the non-solvent in a volatile solvent, desirably having a boiling point below about 1500C and preferably below about 100 C, to form a casting liquid. The liquid is either cast onto a support or former to give a film of the desired shape, or is extruded or spun to produce a hollow fibre structure, and the solvents are evaporated from the solution. The casting process can either be a wet process which involves casting into a liquid bath, with partial evaporation occurring in the bath, or it may be a dry process that involves cast inS into a controlled atmosphere, generally with complete evaporation. If any of the non-solvent is incapable of evaporation under the casting conditions (eg. non-solvent having a boiling point in excess of 2000C) then it may be leached from the cast film using a solvent which is also a non-solvent for the polyetherimide.
The process will obviously be designed to form the polymeric microporous membrane as required for a specific end use. For use in microfiltration an unskinned membrane having a pore size that does not vary by a factor of more than 10 over its entire thickness is preferred. For untrafiltration, a skinned membrane is preferred. Pore structure within the membrane may either be substantially symmetric or substantially asymmetric as is well known in the field of microporous membranes.
The selection of solvent in order to obtain a good membrane is important, and different solvents may be suitable for the dry process than for the wet process.
Quite apart from considering the properties of the formed membranes, both flammability and toxicity are important considerations in solvent selection, as for commercial production it is obviously preferable to reduce hazards as far as possible. The preferred solvent used in the method of the invention is N-methylpyrrolidone, which satisfies all the requirements for a suitable phase in version solvent, even though it is relatively low in volatility.
The implication of this is that requires the non-solvent to be a high boiling compound which remains in the nascent membrane together with a significant quantity of Nmethylpyrrolidone after formation of the cast film.
Residual solvent may then be removed from the resultant membrane by washing with water.
Other possible solvents that can be used are dimethyl formamide, dimethyl acetamide, dioxane and methylcarbonate.
AaXn~ than use a single solvent, it is possible to employ solvent blends, certain of which may include Nmethylpyrrolidone. The theory of solvent blending is known and described, for example in "Handbook of Solubility
Parameters" by Allan F M Barton, published by CRC Press in 1983.
Suitable choice of non-solvent is as important as suitable choice of solvent. Selection of non-solvent is not only a function of the nature of the polyetherimide, but also of the way that non-solvent combines with the solvent in controlling or influencing the membrane formation. In general, the non-solvent must be a non solvent for the polyetherimide but must be soluble in the solvent. Non-solvent tolerance requires that the polymer solution be able to contain within the formulation enough non-solvent (at reasonable processing temperature) to invert and form a microporous membrane of high void volume, that is a membrane with greater than sixty per cent void volume.One of the functions of the non-solvent is that of being the pore former, ie. it is the presence of the nonsolvent in the nascent membrane and the subsequent removal of the non-solvent that causes the pores to be formed in the membrane.
The preferred non-solvent in the method of the invention is one or more polyethylene glycols having molecular weights in the range of from about 200 to about 6,000. Particularly preferred is polyethylene glycol 400, which is a colourless, odourless liquid at room temperature, setting as a soft wax at about 50C. It is soluble in water in all proportions and is also soluble in
N-methylpyrrolidone. It is essentially a non-hazardous substance, and as a pore former, it is well tolerated in the polymer solution, and can be present in up to 30% by weight of the casting liquid.
Additional non-solvents, such as glycerol or water may also be ncl^ed # in the casting liquid. The liquid may also contain swelling agents such as polyvinyl pyrolidene or a polyvinyl alcohol, and/or modifying agents.
Membranes have been prepared by both the wet process and the dry process methods from casting liquids containing only polyetherimide, N-methylpyrrolidone and polyethylene glycol 400. An entire range of membranes from unskinned, open microporous membranes for microfiltration to skinned membranes ultrafiltration have been produced. In general, void volume of the membrane (usually measured by reference to the bubble point of the membrane) is controlled by the content of the non-solvent or pore forming material, and by the rate of transition of the casting liquid from sol to gel during the phase inversion process. Void volume increases with pore former content and with the speed of sol to gel transition. Control of these variables to achieve optimal porosity is well known in this field.Skin formation on microporous membranes is obtained most efficiently by the wet process, where the molecular weight cut off of the membrane is controlled by the temperature of the gelation bath into which the membrane is cast, and by the solvent content. However, membranes produced by the wet process tend to be less asymmetric in pore size through the membrane, as again is well understood in the field.
In general, during dry process membrane production the nominal pore size rating is controlled by the rate of evaporation and the original casting formulation. For a given formulation, optimal permeability giving high flow rates for given pore size rating is achieved by rapid desolvation during processing. This rapid desolvation also gives rise to increasing asymmetry ranging from 2:1 to 5:1 as evaporation loss increases. Again for a given formulation a pore size rating range of membranes can be produced according to the evaporative conditions applied.
It has already been mentioned that the basic membrane be odifec either by c-aft ng a aadLt Wz.al cherloal moiety onto the polyetherimide by reaction with the carbonyl group thereof, or by impregnating the polyetherimide with a polymer which is immobilised within the porous structure of the polyetherimide by a cross linking agent.
The former method is desirably carried out by reacting the formed membrane with the additional chemical moiety, which becomes attached to the carbonyl groups by covalent bonding. In the preferred form of the second method the cross-linking agent is dissolved in the casting liquid, and after the extraction of solvent from the cast layer the membrane is impregnated with the polymer which becomes cross-linked in situ within the membrane structure. The cross-linking agent that is used should not affect the phase inversion process for membrane formation. The crosslinking reaction may be allowed to proceed normally, or may desirably be catalysed, for example with caustic or with heat.
In order that the invention may be better understood some examples of membranes and formation methods in accordance with the invention will now be described in more detail, by way of example only. In the examples the polyetherimide used is ULTEM 1000 from the General Electric
Company. This is a polyetherimide of formula (I), wherein n equals 3 and m is between 5 and 100, the material being a mixture of molecular chains of varying length. The material is an amorphous, thermoplastic resin offering good mechanical strength and high heat resistence, with a glass transition temperature of 2150C. The excellent chemical resistance of this material may be summarised in the following table:
TABLE 1 chemical Resistance Of Polyetherimide To
Aqueous Solutions At 20 (100 Day immersion) x Retention Of Chemical (Concentration) Tensile Strength % Weight Gain
Distilled Water 94 1.18
Citric acid (40%) 96 1.06
Hydrochloric acid (20%) 99 0.61
PhosphoRic acid (20%) 97 0.99
Sulfuric acid (20%) 97 0.89
Chromic acid (15%) 94 0.73
Formic acid (10z.) 94 1.29
Nitric acid (20%) 96 1.07
Acetic acid (20%) 95 1.15 Potassium hydroxide (10%) 97 1.55
Ammonium hydroxide (10%) 68 1.79
Sodium hydroxide (10%) 97 1.00 TABLE 2 Resistance of Polyetherimide To Organic Solvents (5 day immersion at 20 C)
Organic Chemicals Resistance Acetone Butyl Alcohol I
Carbon Ietrachloride I
Chloroform P Cyc I ohexane I ,3 Dioxolane S
1 , 4 Dioxane S Ethanol 2-Ethoxyethanol (Cellosolve) I
Ethyl Acetate I
Ethyl Ether I
Freon TF I
Hexane I Isopropanol Methanol I
Methylene Dichloride P
Methylethylketone I
N.Methyl Pyrrolidone S
Phenol (Saturated Solution) I
Propylene Glycol I
Tetrachloroethylene I loluene 1,1,2-lrichloroethane P
Triethyphosphate Xylere I = Insoluble P = Partially Soluble S - Soluble
EXAMPLE 1
A casting Liquid of the following composition was prepared.
ULTEM 1000 12 (% by weight)
N-methyl pyrrolidone 68
Polyethylene glycol 400 20
The solution was cast to a thickness of 350 micron on a sheet of polyethylene coated paper which was placed in an extraction tunnel. The solvent was allowed to evaporate in the tunnel at an air velocity of 450 ft per minute. The membrane formation was complete within 10 minutes.
EXAMPLE 2
The membrane in this example was prepared in an identical manner to that in Example 1, except that the casting liquid also contained 0.65% of an epoxy resin (polybed 812) based on the total weight of the solution.
The epoxy resin was distributed substantially evenly throughout the membrane, and provided sites to which could be fixed other substances that would not react with the polyetherimide. For example, the epoxy resin could be used in fixing amine groups such as tetraethyl pentamine or polyethyleneimine.
EXAMPLE 3
The membrane in this example was prepared as in
Example 1, except that after casting the liquid film which was supported by the paper, was gently lowered into a water bath at 30C whereupon the membrane was formed. The membrane was found to be effective in filtering out molecules with molecular weight greater than 90,000 dalton.
The membranes prepared from the above examples have the following characteristics:
Bubble point Water Thickness Ratio of
(psi) (spa) flowrate (microns) Asymmetry
Example 1 57 393 20 87.5 3:1
Example 2 50 345 15.4 75.0 3:1
Example 3 over over 0.12 80 Skinned
100 690 * in ml/cm2/min at 69 kPa (10 psi) differential pressure
Membranes made in accordance with Example 1 were tested in comparison with conventional membranes of similar bubble point, made respectively from Nylon 66 and from mixed cellulose esters.The following properties were noted:
Properties Polyetherimide Nylon 66 Mixed Esters
Cellulose
Bubble point (psi) 50 - 57 60 60 Nominal pore size 0.2/ 0.2# 0.2 Working pH 1 - 10 4 - 12 4 - 8
Working 0 - 150 0 - 130 0 - 121 temperature ( C) Burst strength 70 psi 15 psi 44 psi
(psi)
Stability in Stable Dissolved Dissolved 1M HC1
Stability in Swell but Stable Dissolved 1M NaOH intact
Creepage Low Moderate High
Brittleness Flexible Flexible Very brittle
Corrected for thickness
The superior properties of the membranes of the invention will be readily appreciated.
EXAMPLE 4
The membrane from Example 1 was modified by immersing it in an aqueous solution containing 1 mole per litre of tetraethylpentamine at pH5 and 200C for 6 hours after which the membrane was transferred to a solution of sodium borohydride (0.2 molar) pH9 for a further 6 hours. The membrane which has been modified in this manner showed considerable improvement in its resistance to chlorinated solvents and alkaline. It also acquired the ability to wet out instantly upon contact with water without the aid of any wetting agent or humectant.
EXAMPLE 5
The membrane from Example 2 was modified by impregnating it with a solution containing 10% by weight of polyethyleneimine (molecular weight 40,000 - 70,000) in water then allowed to cure at room temperature for 24 hours. The membrane so modified contained a high level of secondary amine groups which are amenable for further grafting of other reactive groups.
EXAMPLE 6
The membrane from Example 5 was further modified by impregnating it with a solution of 10% polyamido-polyamine epichlorohydrin resin in water pHil and allowed to cure at 500C for 6 hours. The resin employed was supplied by
Hercules Inc under the tradename Polycup 1884. The membrane modified in this manner showed improved retentivity for Pseudomonas diminuta, compared with the membranes of the other Examples.
It will be understood that these examples illustrate only some of the membranes of the invention and that by suitable selection of materials and suitable control of the evaporation and other casting conditions, a wide range of membranes mav be formed. The actual physical form of the finished membrane can be as required for the projected end use, and the membranes may generally take the form of any large surface area bodies, such as for example sheets, ribbons, tubes, hollow fibres or beaded particles.
Claims (23)
1. A microporous membrane for use in filtration, the membrane being formed of a polyetherimide derived from an aromatic bis (ether anhydride) and an organic diamine, and having the formula
wherein n is an integer from 1 to 8, the positions of the oxygen atoms linking the phenylene and phthalimide rings are selected from the 3,3 ; 4,4 or 3,4 positions and mixtures thereof, and m is any integer.
2. A membrane according to Claim 1 in which the aromatic bis (ether anhydride) is 2,2 bis [ 4-(3,4-dicarboxy phenoxy) phenyl] propane dianhydride.
3. A membrane according to Claim 1 or Claim 2 in which the organic diamine is selected from 4,4 diamino diphanyl ether and meta phenylene diamine.
4. A membrane according to any one of the preceding claims in which the average molecular weight of the polyetherimide is from about 10,000 to about 100,000.
5. A membrane according to any one of the preceding claims in which the average molecular weight of the polyetherimide is from about 20,000 to about 60,000.
6. A membrane according to any one of the preceding claims, in which at least one additional chemical moiety is grafted onto the polyetherimide by reaction with a carbonyl group thereof.
7. A membrane according to Claim 6 in which the additional chemical moiety is selected from HCN, amines and phosphorus ylides.
8. A membrane according to any one of Claims 1 to 6 in which the polyetherimide is impregnated with a polymer which is immobilised within the porous structure of the polyetherimide by a crosslinking agent.
9. A membrane according to Claim 8 in which the polymer is a water-soluble polymer.
10. A membrane according to Claim 9 in which the polymer is selected from polyethyleneimine and polyamidopolyamine epichlorohydrin.
11. A method of forming a microporous membrane for use in filtration, the method comprising the steps of forming a casting liquid comprising
a) a polyetherimide derived from an aromatic bis
(ether anhydride) and an organic diamine, and
having the formula
wherein n is an integer from 1 to 8, the
positions of the oxygen atoms linking the
phenylene and phthalimide rings are selected from
the 3,3' ; 4,4' or 3,4' positions and mixtures
thereof, and m is any integer;
b) a solvent for the polyetherimide; and
a) non-solvent liquid that by itself cannot
dissolve the polyetherimide; forming a thin layer of the liquid; and extracting at least part of the solvent and non-solvent from the layer to form the required membrane.
12. A method according to Claim 11 in which the aromatic bis (ether anhydride) is 2,2 bis [ 4-(3,4-dicarboxy phenoxy) phenyl] propane dianhydride.
13. A method according to Claim 11 or Claim 12 in which the organic diamine is selected from 4,4 diamino diphenyl ether and meta phenylene diamine.
14. A method according to any one of Claims 11 to 13 in which the average molecular weight of the polyetherimide is from about 10,000 to about 100,000.
15. A method according to any one of Claims 11 to 14 in which the average molecular weight of the polyetherimide is from about 20,000 to about 60,000
16. A method according to any one of Claims 11 to 15 in which the non-solvent is soluble in the solvent and has a boiling point at least 200C higher than that of the solvent.
17. A method according to any one of Claims 11 to 16 in which the solvent is N-methyl pyrrolidone.
18. A method according to any one of Claims 11 to 17 in which the non-solvent is polyethylene glycol having a molecular weight of from about 200 to about 6,000.
19. A method according to any one of Claims 11 to 18 in which at least one additional chemical moiety is grafted onto the polyetherimide by reaction with a carbonyl group thereof.
20. A method according to Claim 19 in which the grafting is by an addition reaction and the additional chemical moiety is selected from HcN, amines and phosphorous ylides.
21. A method according to any one of Claims 11 to 18 in which the polyetherimide is impregnated with a polymer which is immobilised within the porous structure of the polyetherimide by a cross-linking agent.
22. A method according to Claim 21 in which the cross-linking agent is dissolved in the casting liquid, and after the extraction of solvent from the cast layer the membrane is impregnated with the polymer which becomes cross-linked in situ within the membrane structure.
23. A method according to Claim 22 in which the polymer is selected from polyethyleneimine and polyamidopolyamine epichlorohydrin.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8727216A GB2198739B (en) | 1986-12-03 | 1987-11-20 | Microporous membrane |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB868628938A GB8628938D0 (en) | 1986-12-03 | 1986-12-03 | Microporous polyetherimide membranes |
GB8727216A GB2198739B (en) | 1986-12-03 | 1987-11-20 | Microporous membrane |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8727216D0 GB8727216D0 (en) | 1987-12-23 |
GB2198739A true GB2198739A (en) | 1988-06-22 |
GB2198739B GB2198739B (en) | 1990-06-20 |
Family
ID=26291641
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8727216A Expired GB2198739B (en) | 1986-12-03 | 1987-11-20 | Microporous membrane |
Country Status (1)
Country | Link |
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GB (1) | GB2198739B (en) |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0401005A1 (en) * | 1989-06-01 | 1990-12-05 | E.I. Du Pont De Nemours And Company | Amine-modified polyimide membranes |
EP0422886A1 (en) * | 1989-10-10 | 1991-04-17 | E.I. Du Pont De Nemours And Company | Production of aromatic polyimide membranes |
DE19738856A1 (en) * | 1997-09-05 | 1999-03-11 | Lohmann Therapie Syst Lts | Propellant-free process for the production of sheet-like polymer foams |
GB2356358A (en) * | 1999-11-08 | 2001-05-23 | Downstream Media Ltd | Methods and apparatus for capturing target substances from liquid media |
WO2004031268A1 (en) * | 2002-09-30 | 2004-04-15 | Gkss-Forschungszentrum Geesthacht Gmbh | Polyimide microparticles |
WO2012082611A3 (en) * | 2010-12-14 | 2012-09-07 | Svaya Nanotechnologies, Inc. | Porous films by backfilling with reactive compounds |
US8404278B2 (en) | 2002-09-30 | 2013-03-26 | Helmholtz-Zentrum Geesthacht Zentrum fur Material und Kusten forschung GmbH | Polyimide microparticles |
US9387505B2 (en) | 2012-09-17 | 2016-07-12 | Eastman Chemical Company | Methods, materials and apparatus for improving control and efficiency of layer-by-layer processes |
US9393589B2 (en) | 2011-02-15 | 2016-07-19 | Eastman Chemical Company | Methods and materials for functional polyionic species and deposition thereof |
US9395475B2 (en) | 2011-10-07 | 2016-07-19 | Eastman Chemical Company | Broadband solar control film |
US9453949B2 (en) | 2014-12-15 | 2016-09-27 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9817166B2 (en) | 2014-12-15 | 2017-11-14 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9891357B2 (en) | 2014-12-15 | 2018-02-13 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9891347B2 (en) | 2014-12-15 | 2018-02-13 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US10338287B2 (en) | 2017-08-29 | 2019-07-02 | Southwall Technologies Inc. | Infrared-rejecting optical products having pigmented coatings |
US10613261B2 (en) | 2018-04-09 | 2020-04-07 | Southwall Technologies Inc. | Selective light-blocking optical products having a neutral reflection |
US10627555B2 (en) | 2018-04-09 | 2020-04-21 | Southwall Technologies Inc. | Selective light-blocking optical products having a neutral reflection |
US11747532B2 (en) | 2017-09-15 | 2023-09-05 | Southwall Technologies Inc. | Laminated optical products and methods of making them |
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Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0401005A1 (en) * | 1989-06-01 | 1990-12-05 | E.I. Du Pont De Nemours And Company | Amine-modified polyimide membranes |
EP0422886A1 (en) * | 1989-10-10 | 1991-04-17 | E.I. Du Pont De Nemours And Company | Production of aromatic polyimide membranes |
DE19738856A1 (en) * | 1997-09-05 | 1999-03-11 | Lohmann Therapie Syst Lts | Propellant-free process for the production of sheet-like polymer foams |
DE19738856C2 (en) * | 1997-09-05 | 2001-06-13 | Lohmann Therapie Syst Lts | Propellant-free process for the production of sheet-like polymer foams |
GB2356358A (en) * | 1999-11-08 | 2001-05-23 | Downstream Media Ltd | Methods and apparatus for capturing target substances from liquid media |
GB2356358B (en) * | 1999-11-08 | 2003-10-29 | Downstream Media Ltd | Methods and apparatus for capturing target substances from liquid media |
US8404278B2 (en) | 2002-09-30 | 2013-03-26 | Helmholtz-Zentrum Geesthacht Zentrum fur Material und Kusten forschung GmbH | Polyimide microparticles |
WO2004031268A1 (en) * | 2002-09-30 | 2004-04-15 | Gkss-Forschungszentrum Geesthacht Gmbh | Polyimide microparticles |
DE10245545B4 (en) * | 2002-09-30 | 2008-09-18 | Gkss-Forschungszentrum Geesthacht Gmbh | Use of a functionalization solution for the production of polyimide microparticles |
WO2012082611A3 (en) * | 2010-12-14 | 2012-09-07 | Svaya Nanotechnologies, Inc. | Porous films by backfilling with reactive compounds |
US8277899B2 (en) | 2010-12-14 | 2012-10-02 | Svaya Nanotechnologies, Inc. | Porous films by backfilling with reactive compounds |
US9393589B2 (en) | 2011-02-15 | 2016-07-19 | Eastman Chemical Company | Methods and materials for functional polyionic species and deposition thereof |
US9395475B2 (en) | 2011-10-07 | 2016-07-19 | Eastman Chemical Company | Broadband solar control film |
US9387505B2 (en) | 2012-09-17 | 2016-07-12 | Eastman Chemical Company | Methods, materials and apparatus for improving control and efficiency of layer-by-layer processes |
US9453949B2 (en) | 2014-12-15 | 2016-09-27 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9817166B2 (en) | 2014-12-15 | 2017-11-14 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9891357B2 (en) | 2014-12-15 | 2018-02-13 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US9891347B2 (en) | 2014-12-15 | 2018-02-13 | Eastman Chemical Company | Electromagnetic energy-absorbing optical product and method for making |
US10338287B2 (en) | 2017-08-29 | 2019-07-02 | Southwall Technologies Inc. | Infrared-rejecting optical products having pigmented coatings |
US11747532B2 (en) | 2017-09-15 | 2023-09-05 | Southwall Technologies Inc. | Laminated optical products and methods of making them |
US10613261B2 (en) | 2018-04-09 | 2020-04-07 | Southwall Technologies Inc. | Selective light-blocking optical products having a neutral reflection |
US10627555B2 (en) | 2018-04-09 | 2020-04-21 | Southwall Technologies Inc. | Selective light-blocking optical products having a neutral reflection |
Also Published As
Publication number | Publication date |
---|---|
GB8727216D0 (en) | 1987-12-23 |
GB2198739B (en) | 1990-06-20 |
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Legal Events
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732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
PE20 | Patent expired after termination of 20 years |
Effective date: 20071119 |